{"format":"yaani.bundle.v2.2","release_id":"01a1396b-62dc-71b8-84af-2f2155230dec","published_at":"2026-10-14T07:58:28Z","content_lang":"ar-EG","subject":{"id":"chemistry","names":{"ar":"الكيمياء","en":"Chemistry"}},"edition":{"id":"chem-s3-en","subject_id":"chemistry","subject_lang":"en","title":"Chemistry · Grade 12 · English"},"chapter":{"id":"chem-s3-en.ch1","ord":1,"title":"Transition Elements"},"concepts":[{"id":"acid.metal-acid-reaction","kind":"concept","title":"Metal + dilute acid","titles":{"en":"Metal + dilute acid"},"summary":"An active metal reacts with a dilute acid to give a salt and hydrogen gas (e.g. $\\ce{Zn + 2HCl -> ZnCl2 + H2}$).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ active metal لما يتفاعل مع dilute acid بيدّي salt و hydrogen gas (زي $\\ce{Zn + 2HCl -> ZnCl2 + H2}$).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الفلز مع الحمض المخفف"]},"prereq_ids":["chem.acids-bases-salts","chem.activity-series"],"in_chapter":true,"misconceptions":[{"id":"acid.metal-acid-reaction.mc1","label":"Metal + dilute acid gives a salt and water.","explanation":"An active metal (one above hydrogen in the activity series) and a dilute acid give a salt and hydrogen gas: the metal takes the place of the hydrogen in the acid, and the hydrogen leaves as $\\ce{H2}$ gas, so the mixture fizzes, e.g. $\\ce{Mg + 2HCl -> MgCl2 + H2}$. A salt and water come from a metal oxide (or a base) with an acid: the oxide's oxygen joins the acid's hydrogen, e.g. $\\ce{MgO + 2HCl -> MgCl2 + H2O}$, and no gas is given off.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الـ active metal (اللي فوق الـ hydrogen في الـ activity series) مع الـ dilute acid بيدّي salt و hydrogen gas: الـ metal بياخد مكان الـ hydrogen اللي في الـ acid، والـ hydrogen بيطلع $\\ce{H2}$ gas فالمحلول يفوّر، زي $\\ce{Mg + 2HCl -> MgCl2 + H2}$. أما الـ salt والـ water فبييجوا من metal oxide (أو base) مع acid: الـ oxygen اللي في الـ oxide بيتّحد مع الـ hydrogen بتاع الـ acid، زي $\\ce{MgO + 2HCl -> MgCl2 + H2O}$، ومن غير ما يطلع أي gas.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"acid.metal-acid-reaction.mc2","label":"Every metal gives hydrogen with a dilute acid.","explanation":"Only metals above hydrogen in the activity series take the place of hydrogen in a dilute acid and give hydrogen gas, e.g. magnesium, zinc and iron. Metals below hydrogen, such as copper, do not react with dilute hydrochloric acid or dilute sulphuric acid, so no salt forms and no hydrogen is given off.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الـ metals اللي فوق الـ hydrogen في الـ activity series هي بس اللي بتاخد مكان الـ hydrogen في الـ dilute acid وتطلّع hydrogen gas، زي الـ magnesium والـ zinc والـ iron. أما الـ metals اللي تحت الـ hydrogen، زي الـ copper، فمبتتفاعلش مع الـ dilute hydrochloric acid ولا الـ dilute sulphuric acid، فلا بيتكوّن salt ولا بيطلع hydrogen.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"acid.metal-acid-reaction.mc3","label":"The gas from a metal and an acid is carbon dioxide.","explanation":"Carbon dioxide comes from a carbonate with an acid, because the carbonate holds the carbon, e.g. $\\ce{Na2CO3 + 2HCl -> 2NaCl + H2O + CO2}$. An active metal with dilute hydrochloric or sulphuric acid takes the place of the acid's hydrogen, so the gas it gives is hydrogen, e.g. $\\ce{Zn + 2HCl -> ZnCl2 + H2}$. Both reactions fizz, so the fizz alone does not tell which gas it is.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الـ carbon dioxide بيطلع من carbonate مع acid، لأن الـ carbon موجود في الـ carbonate، زي $\\ce{Na2CO3 + 2HCl -> 2NaCl + H2O + CO2}$. إنما الـ active metal مع الـ dilute hydrochloric acid أو الـ dilute sulphuric acid بياخد مكان الـ hydrogen اللي في الـ acid، فالـ gas اللي بيطلع هو الـ hydrogen، زي $\\ce{Zn + 2HCl -> ZnCl2 + H2}$. التفاعلين بيفوّروا، فالفوران لوحده مش بيقول الـ gas ده إيه.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":56,"page_to":56,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"alloy.definition-preparation","kind":"concept","title":"Alloys: definition and preparation","titles":{"en":"Alloys: definition and preparation"},"summary":"An alloy is usually made of two or more metals (ferrochromium, ferromanganese, ferrovanadium, ferronickel) or a metal plus a non-metal such as carbon (steel). Prepared by melting the components together and cooling slowly, or by electrodeposition of two or more metals at the same time (e.g. coating iron handles with brass, Cu + Zn, from a solution of copper and zinc ions).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ alloy غالبًا بيتكوّن من اتنين metals أو أكتر (زي الـ ferrochromium والـ ferromanganese والـ ferrovanadium والـ ferronickel)، أو metal ومعاه non-metal زي الـ carbon في الـ steel. بيتحضّر بطريقتين: إننا نصهر المكونات مع بعض ونسيبها تبرد بالراحة، أو بالـ electrodeposition لاتنين metals أو أكتر في نفس الوقت (زي طلاء مقابض الـ iron بالـ brass، Cu + Zn، من محلول فيه ions الـ copper والـ zinc). المطلوب: تعرّف الـ alloy وتسمّي الطريقتين.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["السبيكة: يعني إيه وبتتعمل إزاي؟"]},"prereq_ids":["chem.electroplating-basic","chem.elements-compounds-mixtures","chem.metal-properties","phys.states-melting-boiling"],"in_chapter":true,"misconceptions":[{"id":"alloy.definition-preparation.mc1","label":"Alloys contain only metals.","explanation":"No: an alloy is usually two or more metals, but it can also be a metal plus a non-metal. Steel, for example, is iron with carbon, and carbon is a non-metal.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، فيه alloys فيها non-metal: الـ steel مثلًا فيه carbon مع الـ iron.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"alloy.definition-preparation.mc2","label":"Every alloy is a chemical compound.","explanation":"No. In interstitial and substitutional alloys the atoms simply take places in the metal's lattice; steel, for example, is iron with carbon atoms in the spaces between iron atoms. A chemical compound forms in one type, the intermetallic alloy, such as cementite $\\ce{Fe3C}$.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الـ alloy مش لازم يبقى chemical compound. الـ steel مثلًا هو iron مع carbon من غير صيغة ثابتة، والاتحاد الكيميائي اللي بيكوّن compound بيحصل في نوع واحد من الـ alloy، هو الـ intermetallic.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys","section_title":"Alloys","section_path":["Transition Elements","Alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.preparation","section_title":"Preparation of alloys","section_path":["Transition Elements","Alloys","Preparation of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"alloy.intermetallic","kind":"concept","title":"Intermetallic alloys","titles":{"en":"Intermetallic alloys"},"summary":"The components combine chemically to form a compound whose formula does not obey the valency rules; the metals are not from the same group. Examples: duralumin (Al-Ni and Al-Cu), lead-gold Au2Pb, cementite Fe3C.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"في الـ intermetallic alloy، العناصر اللي فيه بتتحد كيميائيًا وبتكوّن compound، والـ formula بتاعه مش ماشية على قواعد الـ valency، والـ metals اللي فيه مش من نفس الـ group. أمثلة: الـ duralumin (Al-Ni و Al-Cu)، والـ lead-gold Au2Pb، والـ cementite Fe3C. المطلوب: إنك تصنّف الأمثلة وتشرح ليه الـ formulas بتاعتها مش ماشية على الـ valency.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["السبائك البين فلزية"]},"prereq_ids":["alloy.definition-preparation","alloy.interstitial","chem.valency-formulas","pt.groups-periods"],"in_chapter":true,"misconceptions":[{"id":"alloy.intermetallic.mc1","label":"Intermetallic alloys are physical mixtures.","explanation":"No. In an intermetallic alloy the components combine chemically, so it is a chemical compound, not a physical mixture: cementite $\\ce{Fe3C}$ and lead-gold $\\ce{Au2Pb}$ have their own formulas, even though these formulas do not obey the valency rules.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ intermetallic alloys مش خليط فيزيائي؛ دي chemical compounds، لأن العناصر اللي فيها بتتحد كيميائيًا.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"alloy.intermetallic.mc2","label":"Cementite Fe3C is interstitial like steel.","explanation":"Both contain Fe and C, but they are different types. In steel the small carbon atoms sit in the spaces between iron atoms (interstitial); in cementite iron and carbon combine chemically into the compound $\\ce{Fe3C}$, whose formula does not obey the valency rules (intermetallic).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"صحيح إن الاتنين فيهم Fe و C، لكن في الـ steel ذرات الـ C بتقعد في الفراغات بين ذرات الـ Fe، فهو interstitial. أما في الـ cementite فالـ Fe والـ C بيتحدوا كيميائيًا ويكوّنوا compound هو Fe3C، والـ formula دي مش ماشية على الـ valency، فهو intermetallic.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"relation":"based_on"}]},{"id":"alloy.interstitial","kind":"concept","title":"Interstitial alloys","titles":{"en":"Interstitial alloys"},"summary":"In a pure metal the atoms are packed in close rows, and hammering lets layers slip over each other. Putting atoms of an element with a small atomic size into the spaces of the lattice blocks this slipping, so the metal becomes harder and its malleability, ductility, melting point, electrical conductivity and magnetic properties change. Example: steel (iron + carbon).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"في الـ pure metal الذرات مترصوصة في صفوف متلاصقة، ولما تطرقه الطبقات بتنزلق فوق بعض. لما ندخّل ذرات عنصر الـ atomic size بتاعه صغير في فراغات الـ lattice، الانزلاق ده بيتمنع، فالـ metal بيبقى أصلب، وكمان الـ malleability والـ ductility والـ melting point والـ electrical conductivity والـ magnetic properties بتاعته بتتغير. مثال: الـ steel (iron + carbon). المطلوب: تشرح الفكرة دي برسمة الـ lattice (شكل 1-5 a, b, c).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["السبائك البينية"]},"prereq_ids":["alloy.definition-preparation","bond.metallic-bond"],"in_chapter":true,"misconceptions":[{"id":"alloy.interstitial.mc1","label":"The small atoms replace metal atoms.","explanation":"No: the small atoms (such as carbon in steel) do not take the place of metal atoms; they fit into the spaces between them in the crystal lattice. Atoms of another metal taking the place of metal atoms is a substitutional alloy.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الذرات الصغيرة مش بتاخد مكان ذرات الـ metal؛ هي بتقعد في الفراغات اللي بينها.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"alloy.interstitial.mc2","label":"Adding carbon makes iron softer.","explanation":"The opposite: the small carbon atoms sit in the spaces of the iron lattice and stop the layers from slipping over each other, so steel is harder than pure iron.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"بالعكس: ذرات الـ carbon الصغيرة بتقعد في فراغات الـ lattice بتاع الـ iron وبتمنع الطبقات إنها تنزلق، فالـ steel بيبقى أصلب من الـ iron النقي.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"alloy.interstitial.mc3","label":"Steel and cementite are the same alloy type.","explanation":"They are different types. Steel is interstitial: carbon atoms sit in the spaces of the iron lattice. Cementite $\\ce{Fe3C}$ is intermetallic: iron and carbon combine chemically into a compound.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ steel نوعه interstitial: ذرات الـ carbon قاعدة في الفراغات. أما الـ cementite (Fe3C) فنوعه intermetallic: الـ iron والـ carbon بيتحدوا كيميائيًا.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.properties","section_title":"Properties of Iron","section_path":["Transition Elements","Iron","Properties of Iron"],"relation":"based_on"}]},{"id":"alloy.substitutional","kind":"concept","title":"Substitutional alloys","titles":{"en":"Substitutional alloys"},"summary":"Some atoms of the pure metal are replaced by atoms of another metal that has the same atomic radius, crystal lattice and chemical properties. Examples: ferrochrome (Fe-Cr) in stainless steel, copper-gold, ferronickel.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"بعض ذرات الـ pure metal بيحل مكانها ذرات metal تاني ليه نفس الـ atomic radius ونفس الـ crystal lattice ونفس الـ chemical properties. أمثلة: الـ ferrochrome (Fe-Cr) اللي في الـ stainless steel، والـ copper-gold، والـ ferronickel. المطلوب: تقول الشروط وتعرف تصنّف الأمثلة؛ والفكرة مرتبطة بإن الـ atomic radius للـ transition metals تقريبًا ثابت.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["السبائك الاستبدالية"]},"prereq_ids":["alloy.definition-preparation","te.atomic-radius"],"in_chapter":true,"misconceptions":[{"id":"alloy.substitutional.mc1","label":"Any two metals can form a substitutional alloy.","explanation":"No: being metals is not enough. The two metals must have the same atomic radius, the same crystal lattice and the same chemical properties, so that atoms of one can take the place of atoms of the other.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، مجرد إنهم metals مش كفاية. لازم الشروط التلاتة مع بعض: نفس الـ atomic radius ونفس الـ crystal lattice ونفس الـ chemical properties.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"alloy.substitutional.mc2","label":"Fe-Cr is an interstitial alloy.","explanation":"No. Cr and Fe have almost the same atomic radius (1.17 and 1.16 in the book's table), so Cr atoms take the place of some Fe atoms: ferrochrome (Fe-Cr) is a substitutional alloy. Interstitial means small atoms such as carbon fit into the spaces, as in steel.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ atomic radius للـ Cr والـ Fe تقريبًا واحد (1.17 و1.16)، فذرات الـ Cr بتحل مكان بعض ذرات الـ Fe: يعني الـ ferrochrome (Fe-Cr) substitutional alloy. الـ interstitial بيبقى لما ذرات صغيرة جدًا زي الـ carbon تدخل في الفراغات، زي الـ steel.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"relation":"based_on"}]},{"id":"atom.atomic-mass-number","kind":"concept","title":"Atomic number and mass number","titles":{"en":"Atomic number and mass number"},"summary":"Atomic number = number of protons (= electrons in a neutral atom); mass number = protons + neutrons.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ Atomic number = عدد الـ protons (وهو نفسه عدد الـ electrons في الذرة المتعادلة)؛ والـ mass number = protons + neutrons.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["العدد الذري والعدد الكتلي"]},"prereq_ids":["atom.structure","found.four-operations"],"in_chapter":true,"misconceptions":[]},{"id":"atom.aufbau","kind":"concept","title":"Aufbau principle (order of filling)","titles":{"en":"Aufbau principle (order of filling)"},"summary":"Electrons fill sublevels in a fixed order: 1s 2s 2p 3s 3p 4s 3d 4p ... Evidence in period 4: K ([Ar] 4s1) and Ca ([Ar] 4s2, book p.8) put their electrons in 4s, and 3d starts filling only from Sc ([Ar] 4s2 3d1). This is the order of filling only; when ions form, the 4s electrons (outer level, n = 4) leave first.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ electrons بتملا الـ sublevels بترتيب ثابت: 1s 2s 2p 3s 3p 4s 3d 4p ... والدليل في الـ period 4: الـ K ([Ar] 4s1) والـ Ca ([Ar] 4s2، الكتاب ص 8) بيحطوا الـ electrons بتاعتهم في الـ 4s، والـ 3d مش بيبدأ يتملي غير من عند الـ Sc ([Ar] 4s2 3d1). ده ترتيب الملء تحديدًا؛ لكن لما الـ ions بتتكوّن، الـ electrons بتاعة الـ 4s (المستوى الخارجي، n = 4) هي اللي بتخرج الأول.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["مبدأ البناء: 4s قبل 3d"]},"prereq_ids":["atom.orbitals"],"in_chapter":true,"misconceptions":[{"id":"atom.aufbau.mc1","label":"3d fills before 4s because 3 < 4.","explanation":"K and Ca use 4s; 3d starts at Sc.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، رقم المستوى لوحده مش هو اللي بيحدد الترتيب: الـ K والـ Ca بيحطوا الـ electrons في الـ 4s، والـ 3d بيبدأ يتملي من عند الـ Sc.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"atom.aufbau.mc2","label":"The sublevel filled first is also the last to lose electrons.","explanation":"In ions the outer 4s electrons leave first.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"بالعكس: في الـ ions، الـ electrons بتاعة الـ 4s (المستوى الخارجي) هي اللي بتخرج الأول، مع إن الـ 4s اتملى قبل الـ 3d.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"atom.electron-configuration-writing","kind":"skill","title":"Writing electronic configurations","titles":{"en":"Writing electronic configurations"},"summary":"Writing an atom's configuration sublevel by sublevel (e.g. 1s2 2s2 2p6 ...) and in short form with a noble-gas core such as [Ar].","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"إزاي تكتب الـ configuration بتاع الذرة sublevel ورا sublevel (زي 1s2 2s2 2p6 ...)، وإزاي تكتبه مختصر بـ noble-gas core زي [Ar].","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["كتابة التوزيع الإلكتروني"]},"prereq_ids":["atom.aufbau","atom.electron-spin-pauli","pt.groups-periods"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"atom.electron-spin-pauli","kind":"concept","title":"Electron spin and the Pauli principle","titles":{"en":"Electron spin and the Pauli principle"},"summary":"Each electron spins and acts like a tiny magnet; two electrons sharing an orbital must have opposite spins (shown as up and down arrows), so their magnetic effects cancel.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"كل electron بيعمل spin، فبيتصرّف كأنه مغناطيس صغير. ولو اتنين electrons في نفس الـ orbital، لازم يكون ليهم opposite spins (بنرسمهم سهم لفوق وسهم لتحت)، وعشان كده التأثير المغناطيسي بتاعهم بيلغي بعضه.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["غزل الإلكترون (↑↓)"]},"prereq_ids":["atom.orbitals","phys.magnetic-field"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"}]},{"id":"atom.energy-levels","kind":"concept","title":"Main energy levels","titles":{"en":"Main energy levels"},"summary":"Electrons are arranged in main energy levels (K, L, M, N ...) around the nucleus; level n holds at most 2n2 electrons (this rule applies to the first four levels only); outer electrons are the valence electrons.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ electrons بتترتب حوالين الـ nucleus في main energy levels (K, L, M, N ...). المستوى رقم n أقصى عدد electrons يشيله هو 2n2 (والقاعدة دي بتنطبق على أول أربع مستويات تحديدًا). والـ electrons اللي في المستوى الخارجي هي الـ valence electrons (ده في عناصر المجموعات الرئيسية).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["مستويات الطاقة وتوزيع الإلكترونات"]},"prereq_ids":["atom.atomic-mass-number"],"in_chapter":true,"misconceptions":[]},{"id":"atom.hund-rule","kind":"concept","title":"Hund's rule and orbital-box diagrams","titles":{"en":"Hund's rule and orbital-box diagrams"},"summary":"Within a sublevel, electrons occupy orbitals singly with parallel spins before any pairing; drawn as boxes with arrows.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"جوه الـ sublevel الواحد، الـ electrons بتقعد في الـ orbitals فرادى الأول وبـ parallel spins، قبل ما أي أزواج تبتدي؛ وبنرسمها مربعات جواها أسهم.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["قاعدة Hund ورسم الأوربيتالات"]},"prereq_ids":["atom.electron-spin-pauli"],"in_chapter":true,"misconceptions":[{"id":"atom.hund-rule.mc1","label":"Electrons pair up in the first orbital before filling the others.","explanation":"No. Within a sublevel, electrons occupy the empty orbitals singly, with parallel spins, before pairing starts. In the first transition series the five 3d orbitals take one electron each up to manganese ($3d^5$); pairing begins after manganese.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ electrons كلها negative وبتتنافر، فمش هتتزنق في أول orbital وجنبها orbital فاضي. كل electron بياخد orbital فاضي لوحده الأول بـ parallel spins، والأزواج بتبتدي بعد ما الـ orbitals كلها ياخدوا electron واحد.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic.ex-a","section_title":"Paramagnetic or diamagnetic","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties","Paramagnetic or diamagnetic"],"relation":"based_on"}]},{"id":"atom.isotopes","kind":"concept","title":"Isotopes and average atomic mass","titles":{"en":"Isotopes and average atomic mass"},"summary":"Isotopes are atoms of the same element with the same atomic number but different mass numbers (different neutrons); an element's atomic mass is the average of its isotopes weighted by their abundance.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ isotopes هي ذرات من نفس العنصر، ليها نفس الـ atomic number لكن الـ mass numbers بتاعتها مختلفة (عشان عدد الـ neutrons مختلف). والـ atomic mass بتاعة العنصر هي متوسط الـ isotopes بتاعته، موزون حسب نسبة وجود كل isotope.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["النظائر ومتوسط الكتلة الذرية"]},"prereq_ids":["atom.atomic-mass-number","found.percentages"],"in_chapter":true,"misconceptions":[{"id":"atom.isotopes.mc1","label":"Atomic mass in the table is the mass number of a single atom.","explanation":"No. The atomic mass in the table is the average mass of the element's isotopes, weighted by how abundant each one is. That is why it can be a non-whole number, like 35.5 for chlorine, although no chlorine atom has a mass of 35.5.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الرقم اللي في الجدول مش الـ mass number لذرة واحدة. ده متوسط الـ isotopes موزون حسب نسبة وجود كل واحد، وعشان كده ممكن ميطلعش رقم صحيح، زي 35.5 للـ chlorine، مع إن مفيش ذرة chlorine كتلتها 35.5.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.mass","section_title":"The atomic mass","section_path":["Transition Elements","The general properties of the first transition elements","The atomic mass"],"relation":"based_on"}]},{"id":"atom.orbitals","kind":"concept","title":"Orbitals","titles":{"en":"Orbitals"},"summary":"Sublevels are made of orbitals: s has 1, p 3, d 5, f 7; each orbital holds at most two electrons.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ sublevels بتتكوّن من orbitals: الـ s فيه 1، والـ p فيه 3، والـ d فيه 5، والـ f فيه 7. والـ orbital الواحد بيشيل 2 electrons على الأكتر.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الأوربيتالات"]},"prereq_ids":["atom.sublevels"],"in_chapter":true,"misconceptions":[{"id":"atom.orbitals.mc1","label":"An orbital is a circular path (orbit) of the electron.","explanation":"No. An orbital is not a circular path: the electron's exact path cannot be known. An orbital is the region around the nucleus where the electron is most likely to be found, and it holds at most two electrons.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ orbital مش مسار دايري (orbit) بيلف فيه الـ electron. إحنا مانقدرش نحدد المسار بالظبط؛ الـ orbital هو المنطقة اللي حوالين الـ nucleus اللي احتمال وجود الـ electron فيها أكبر ما يمكن.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"atom.structure","kind":"concept","title":"Structure of the atom","titles":{"en":"Structure of the atom"},"summary":"An atom has a tiny nucleus of positive protons and neutral neutrons, with negative electrons around it; a neutral atom has equal protons and electrons.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الذرة فيها nucleus صغيرة جدًا، جواها protons الـ positive و neutrons الـ neutral، وحواليها electrons الـ negative. والذرة المتعادلة عدد الـ protons فيها بيساوي عدد الـ electrons.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["تركيب الذرة"]},"prereq_ids":["phys.electric-charges","sci.matter-particles"],"in_chapter":true,"misconceptions":[]},{"id":"atom.sublevels","kind":"concept","title":"Energy sublevels (s, p, d, f)","titles":{"en":"Energy sublevels (s, p, d, f)"},"summary":"In the first four main energy levels (n = 1–4), level n contains n sublevels (s, p, d, f) holding up to 2, 6, 10, 14 electrons; the d sublevel first appears at n = 3.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"في أول أربع main energy levels (n = 1–4)، المستوى رقم n بيبقى فيه n من الـ sublevels (s, p, d, f)، وبيشيلوا لحد 2 و6 و10 و14 electrons بالترتيب. والـ d sublevel أول ما بيظهر بيظهر عند n = 3.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["المستويات الفرعية s و p و d و f"]},"prereq_ids":["atom.energy-levels"],"in_chapter":true,"misconceptions":[{"id":"atom.sublevels.mc1","label":"Every level has all four sublevels.","explanation":"No. In the first four levels (n = 1–4), level n has n sublevels: level 2 has 2s and 2p but no 2d, and the d sublevel first appears at level 3 (3d).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، في أول أربع مستويات (n = 1–4) المستوى n فيه n من الـ sublevels. يعني المستوى 2 فيه 2s و2p ومافيهوش 2d، والـ d أول ما بيظهر بيظهر في المستوى 3 (3d).","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"bond.chemical-bond-basic","kind":"concept","title":"Ionic and covalent bonds","titles":{"en":"Ionic and covalent bonds"},"summary":"Atoms bond by transferring electrons (ionic bond) or sharing them (covalent bond) to reach a stable arrangement. (A third type, the metallic bond, holds metal atoms together.)","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ atoms ممكن تترابط بإنها تنقل electrons من واحدة للتانية (ionic bond)، أو تشارك فيها (covalent bond)، والهدف إنها توصل لترتيب مستقر. (وفيه نوع تالت بين الـ metal atoms وبعضها، هو الـ metallic bond.)","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الرابطة الأيونية والتساهمية"]},"prereq_ids":["chem.ions"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":66,"page_to":66,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"bond.metallic-bond","kind":"concept","title":"Metallic bond","titles":{"en":"Metallic bond"},"summary":"Metal atoms form a crystal lattice of positive ions held together by their free valence electrons; in general, more bonding electrons give a stronger bond (not a rule for every metal: the chapter's melting-point table breaks it at Mn and Cu). Explains conductivity and why layers can slide (malleability).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ metal atoms بتكوّن crystal lattice من positive ions، ماسكها في بعض الـ free valence electrons بتاعتها. وبشكل عام، bonding electrons أكتر بتدي bond أقوى (لكن دي مش قاعدة لكل الـ metals). والـ bond ده بيفسّر الـ conductivity، وليه الطبقات تقدر تتزحلق على بعض (الـ malleability).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الرابطة الفلزية"]},"prereq_ids":["bond.chemical-bond-basic","chem.metal-properties"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem.acids-bases-salts","kind":"concept","title":"Acids, bases and salts","titles":{"en":"Acids, bases and salts"},"summary":"Acids (e.g. HCl, H2SO4, HNO3), bases/alkalis (e.g. NaOH, NH4OH) and salts formed when they react; common acid and salt names.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الفكرة هنا عن الـ acids (زي HCl و H2SO4 و HNO3)، والـ bases/alkalis (زي NaOH و NH4OH)، والـ salts اللي بتتكوّن لما بيتفاعلوا مع بعض؛ ومعاهم أسامي الـ acid والـ salt المشهورة.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الأحماض والقلويات والأملاح"]},"prereq_ids":["chem.valency-formulas"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":43,"page_to":43,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"}]},{"id":"chem.activity-series","kind":"concept","title":"Chemical activity series of metals","titles":{"en":"Chemical activity series of metals"},"summary":"Metals are ordered by how readily they react (with water, acids, oxygen); metals above hydrogen displace it from dilute acids, and the most active of them also from water.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ metals بتترتب حسب سهولة تفاعلها (مع المية والـ acids والـ oxygen). والـ metals اللي فوق الـ hydrogen في الترتيب ده بتعمل displace للـ hydrogen من الـ dilute acids، والأنشط فيهم بيعمل displace للـ hydrogen من المية كمان.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["سلسلة النشاط الكيميائي"]},"prereq_ids":["chem.equation-balancing","chem.metal-properties"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"chem.ammonia-haber","kind":"concept","title":"Haber-Bosch method for ammonia","titles":{"en":"Haber-Bosch method for ammonia"},"summary":"Ammonia is made industrially from nitrogen and hydrogen, N2 + 3H2 -> 2NH3, using an iron catalyst at high pressure and temperature.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ ammonia بتتحضّر صناعيًا من الـ nitrogen والـ hydrogen: N2 + 3H2 -> 2NH3، والـ iron بيبقى هو الـ catalyst، عند pressure و temperature عاليين.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["تحضير النشادر صناعيًا (هابر-بوش)"]},"prereq_ids":["chem.catalyst","chem.equation-reading"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem.bond-breaking-energy","kind":"concept","title":"Bond breaking and bond forming","titles":{"en":"Bond breaking and bond forming"},"summary":"In a reaction the reactants' bonds break (absorbs energy) and new bonds form in the products (releases energy); the balance is the reaction's heat.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"في أي reaction، الـ bonds اللي في الـ reactants بتتكسر (وده بيمتص energy)، وبتتكوّن bonds جديدة في الـ products (وده بيطلّع energy)؛ والفرق بين الاتنين هو حرارة الـ reaction.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["التفاعل = كسر روابط وتكوين روابط"]},"prereq_ids":["bond.chemical-bond-basic","chem.equation-balancing"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":61,"page_to":61,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"chem.catalyst","kind":"concept","title":"Catalyst","titles":{"en":"Catalyst"},"summary":"A catalyst speeds up a chemical reaction without being used up; it is written over the arrow (e.g. MnO2 in making oxygen from H2O2).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ catalyst بيسرّع الـ chemical reaction من غير ما يتستهلك، وبيتكتب فوق السهم (زي الـ MnO2 في تحضير الـ oxygen من الـ H2O2).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["العامل الحفاز"]},"prereq_ids":["chem.equation-balancing"],"in_chapter":true,"misconceptions":[{"id":"chem.catalyst.mc1","label":"The catalyst is consumed in the reaction.","explanation":"No. A catalyst changes the rate of the reaction without itself being changed: it is left at the end with the same mass, so it can be used again, e.g. $\\ce{MnO2}$ in the decomposition of $\\ce{H2O2}$.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ catalyst مش بيتستهلك في الـ reaction: بيرجع في الآخر بنفس الكتلة، وعشان كده ينفع يتستخدم تاني.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":64,"page_to":65,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem.electroplating-basic","kind":"concept","title":"Electroplating","titles":{"en":"Electroplating"},"summary":"Passing an electric current through a solution of metal ions deposits the metal as a thin coat on the object at the cathode. Formally taught in Ch.4 (Electrochemistry) of the same book; here only the basic idea is needed.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"لما نعدّي electric current في solution فيه metal ions، الـ metal بيترسّب كطبقة رقيقة على الجسم اللي عند الـ cathode. الموضوع ده بيتشرح رسمي في الفصل الرابع (Electrochemistry) من نفس الكتاب؛ هنا مش محتاجين غير الفكرة الأساسية.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الطلاء الكهربي"]},"prereq_ids":["chem.ions","phys.electric-current"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.preparation","section_title":"Preparation of alloys","section_path":["Transition Elements","Alloys","Preparation of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":86,"page_to":86,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"chem.elements-compounds-mixtures","kind":"concept","title":"Elements, compounds and mixtures","titles":{"en":"Elements, compounds and mixtures"},"summary":"A compound is elements chemically combined in fixed ratios with new properties; a mixture is substances mixed physically, keeping their properties and separable by physical means.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ compound عبارة عن elements متحدة كيميائيًا بنسب ثابتة، وبيطلع ليه properties جديدة. أما الـ mixture فهو مواد متخلطة ببعض فيزيائيًا، كل مادة فيه محتفظة بالـ properties بتاعتها، وينفع نفصلهم عن بعض بطرق فيزيائية.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["العنصر والمركب والمخلوط"]},"prereq_ids":["chem.elements-symbols"],"in_chapter":true,"misconceptions":[{"id":"chem.elements-compounds-mixtures.mc1","label":"A mixture and a compound are the same thing.","explanation":"They are different. In a compound, elements are chemically combined in a fixed ratio and the compound has new properties; in a mixture the parts are not combined, their ratio can vary, each keeps its own properties, and they can be separated by physical means.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الاتنين مختلفين. في الـ compound الـ elements متحدة كيميائيًا بنسبة ثابتة وبيطلع properties جديدة، إنما في الـ mixture الأجزاء مش مرتبطة ببعض، فنسبتها ممكن تتغير وكل جزء محتفظ بالـ properties بتاعته.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem.elements-symbols","kind":"concept","title":"Elements and their symbols","titles":{"en":"Elements and their symbols"},"summary":"An element is a pure substance of one kind of atom, written with a Latin-letter symbol (Fe, Cu, Zn, O ...).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ element هو pure substance متكوّنة من نوع واحد من الذرات، وبنكتبه بـ symbol من حروف لاتيني (Fe, Cu, Zn, O ...).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["العناصر ورموزها"]},"prereq_ids":["found.latin-letters","sci.matter-particles"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series","section_title":"The First Transition Series","section_path":["Transition Elements","The First Transition Series"],"relation":"based_on"}]},{"id":"chem.equation-balancing","kind":"skill","title":"Writing and balancing chemical equations","titles":{"en":"Writing and balancing chemical equations"},"summary":"Writing reactants and products with correct formulas and balancing atoms on both sides with coefficients.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"إنك تكتب الـ reactants والـ products بالـ formulas الصح، وبعدين توزن الذرات في الناحيتين باستخدام الـ coefficients.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["كتابة ووزن المعادلة الكيميائية"]},"prereq_ids":["chem.valency-formulas"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem.equation-reading","kind":"concept","title":"Reading equations: states and conditions","titles":{"en":"Reading equations: states and conditions"},"summary":"Reading physical-state symbols (s), (l), (g), (aq), (v), the heating sign (Δ) written over the arrow, and conditions or catalysts written over the arrow (temperature, pressure, catalyst).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"إنك تقرا الـ state symbols اللي بتيجي بعد المادة في المعادلة: (s)، (l)، (g)، (aq)، (v)، وعلامة التسخين (Δ)، والـ conditions أو الـ catalysts اللي بتتكتب فوق السهم (temperature، pressure، catalyst).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["قراءة المعادلة: الحالات والظروف على السهم"]},"prereq_ids":["chem.equation-balancing","phys.states-melting-boiling"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem.ions","kind":"concept","title":"Ions (cations and anions)","titles":{"en":"Ions (cations and anions)"},"summary":"Atoms lose electrons to become positive ions (cations) or gain electrons to become negative ions (anions); the charge equals electrons lost or gained.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الذرة بتفقد electrons فتبقى positive ion (cation)، أو بتكسب electrons فتبقى negative ion (anion). والـ charge بتساوي عدد الـ electrons اللي الذرة فقدتها أو كسبتها.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الأيونات الموجبة والسالبة"]},"prereq_ids":["atom.energy-levels"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem.metal-properties","kind":"concept","title":"Properties of metals and non-metals","titles":{"en":"Properties of metals and non-metals"},"summary":"Metals are shiny, conduct heat and electricity, are malleable and ductile, and mostly solid with high melting points; non-metals mostly lack these.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ metals بتبقى shiny، وبتوصّل الحرارة والكهربا، وهي malleable و ductile، وأغلبها solid والـ melting points بتاعتها عالية؛ أما الـ non-metals فأغلبها مافيهاش الصفات دي.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["خواص الفلزات واللافلزات"]},"prereq_ids":["chem.elements-symbols"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.properties","section_title":"Properties of Iron","section_path":["Transition Elements","Iron","Properties of Iron"],"relation":"based_on"}]},{"id":"chem.mixture-separation","kind":"skill","title":"Separating mixtures","titles":{"en":"Separating mixtures"},"summary":"Mixtures are separated by physical methods using differences in properties: magnet, filtration, flotation/settling, etc.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ mixtures بتتفصل بـ physical methods بتستغل الاختلاف في الخواص بين مكوّناتها: زي الـ magnet، والـ filtration، والـ flotation/settling، وغيرهم.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["فصل مكونات المخلوط"]},"prereq_ids":["chem.elements-compounds-mixtures","phys.magnetic-field"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem.natural-gas-methane","kind":"concept","title":"Natural gas (methane)","titles":{"en":"Natural gas (methane)"},"summary":"Natural gas is a fossil fuel made mostly of methane, CH4, the simplest hydrocarbon.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ natural gas ده fossil fuel، وأغلبه methane، CH4، اللي هو أبسط hydrocarbon.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الغاز الطبيعي (الميثان CH₄)"]},"prereq_ids":["chem.valency-formulas"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem.oxides","kind":"concept","title":"Acidic and basic oxides","titles":{"en":"Acidic and basic oxides"},"summary":"Most metal oxides are basic oxides that react with acids to give a salt and water (e.g. FeO, Fe2O3); most non-metal oxides are acidic oxides (e.g. SO2, CO2).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"أغلب الـ metal oxides بتبقى basic oxides، بتتفاعل مع الـ acids وتدي salt ومية (زي الـ FeO والـ Fe2O3)؛ وأغلب الـ non-metal oxides بتبقى acidic oxides (زي الـ SO2 والـ CO2).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الأكاسيد الحامضية والقاعدية"]},"prereq_ids":["chem.acids-bases-salts","chem.metal-properties"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem.reaction-types","kind":"concept","title":"Types of chemical reactions","titles":{"en":"Types of chemical reactions"},"summary":"Thermal decomposition, simple displacement and double displacement (including precipitation of an insoluble solid and neutralization).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"أنواع التفاعلات هنا: الـ thermal decomposition، والـ simple displacement، والـ double displacement، والأخير ده بيشمل الـ precipitation لـ insoluble solid، وكمان الـ neutralization.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["أنواع التفاعلات الكيميائية"]},"prereq_ids":["chem.acids-bases-salts","chem.equation-balancing"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":83,"page_to":83,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":56,"page_to":56,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"chem.rusting-corrosion","kind":"concept","title":"Rusting and corrosion","titles":{"en":"Rusting and corrosion"},"summary":"Metals such as iron slowly react with oxygen and moisture in air (rusting/corrosion); coatings such as paint, zinc or another metal protect them.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"metals زي الـ iron بتتفاعل بالراحة مع الـ oxygen والـ moisture اللي في الهوا (ده الـ rusting/corrosion)؛ والطبقات اللي بنغطيها بيها، زي الدهان أو الـ zinc أو metal تاني، بتحميها.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الصدأ وتآكل الفلزات"]},"prereq_ids":["chem.oxides"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem.solution-concentration","kind":"concept","title":"Concentrated and dilute solutions","titles":{"en":"Concentrated and dilute solutions"},"summary":"A solution is a solute dissolved in a solvent; a concentrated solution has much solute in a given volume, a dilute one little.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ solution هو solute دايب في solvent. الـ concentrated solution فيه solute كتير في حجم معيّن، والـ dilute فيه solute قليل.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["المحلول المركز والمخفف"]},"prereq_ids":["chem.elements-compounds-mixtures","found.fractions-decimals"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem.valency-formulas","kind":"skill","title":"Valency and writing chemical formulas","titles":{"en":"Valency and writing chemical formulas"},"summary":"Valency is an element's combining capacity; formulas are written by balancing valencies (e.g. Al2O3, FeCl3), including common groups like SO4 and CO3.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ valency هي قدرة العنصر إنه يتحد مع غيره؛ والـ formulas بنكتبها عن طريق إننا نوازن الـ valencies (زي Al2O3 و FeCl3)، ومعاها الـ groups الشائعة زي SO4 و CO3.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["التكافؤ وكتابة الصيغة الكيميائية"]},"prereq_ids":["chem.elements-symbols","found.four-operations"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem.water-of-crystallization","kind":"concept","title":"Water of crystallization","titles":{"en":"Water of crystallization"},"summary":"Some solids contain a fixed number of water molecules in their crystals, written after a dot (e.g. CuSO4.5H2O); heating drives this water off.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"فيه مواد صلبة بتشيل جوه الـ crystals بتاعتها عدد ثابت من الـ water molecules، والعدد ده بيتكتب في الصيغة بعد نقطة (زي CuSO4.5H2O). ولما تسخّنها، الميّة دي بتطلع منها.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["ماء التبلر"]},"prereq_ids":["chem.valency-formulas"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":46,"page_to":47,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"fe.blast-furnace-reduction","kind":"skill","title":"Reduction in the blast furnace","titles":{"en":"Reduction in the blast furnace"},"summary":"Coke burns: C + O2 -> CO2, then CO2 + C -> 2CO; carbon monoxide reduces the ore: 3CO + Fe2O3 -> 2Fe + 3CO2 (above 700 C). Role of coke: fuel and source of the reducing gas CO.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ coke بيتحرق: C + O2 -> CO2، وبعدين CO2 + C -> 2CO؛ والـ carbon monoxide هو اللي بيختزل الـ ore: 3CO + Fe2O3 -> 2Fe + 3CO2 (فوق 700 C). دور الـ coke: وقود، ومصدر للغاز المختزل CO. المطلوب: إنك تكتب المعادلات التلاتة وتقول دور الـ coke.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الاختزال في الفرن العالي (دور فحم الكوك)"]},"prereq_ids":["fe.roasting","redox.basic"],"in_chapter":true,"misconceptions":[{"id":"fe.blast-furnace-reduction.mc1","label":"Coke (carbon) itself reduces the ore directly.","explanation":"Not directly. Coke burns to $\\ce{CO2}$, which reacts with more hot coke to give carbon monoxide; the CO is what reduces the ore: $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$. Coke is the fuel and the source of the reducing gas.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ coke مش هو اللي بيختزل الـ ore على طول؛ الـ CO هو اللي بيعمل كده.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.blast-furnace-reduction.mc2","label":"CO2 is the reducing agent.","explanation":"No. $\\ce{CO2}$ is a product, not the reducing agent. It reacts with hot coke to give $\\ce{CO}$, and CO is the reducing agent that turns $\\ce{Fe2O3}$ into iron.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ CO2 ده ناتج، مش هو اللي بيختزل. الـ CO2 بيتفاعل مع الـ C ويدّي CO، والـ CO هو الـ reducing agent اللي بيختزل الـ Fe2O3 لـ Fe.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q5","section_title":"Explain the role","section_path":["Transition Elements","Evaluation","Explain the role"],"relation":"based_on"}]},{"id":"fe.conversions","kind":"skill","title":"Iron and its oxides: reaction diagrams","titles":{"en":"Iron and its oxides: reaction diagrams"},"summary":"Given a chain such as Fe -> Fe3O4 -> FeO -> Fe2O3 -> Fe or Fe -> FeSO4 -> Fe2O3 -> Fe3O4 -> Fe, choose the reagent and condition for each step (air or steam on red-hot iron; H2 or CO at 400-700 C; heating in air; CO above 700 C; dilute H2SO4; heating FeSO4; CO at 230-300 C) and write balanced equations. Conditions decide the product.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"لما يجيلك مخطط تحويلات زي Fe -> Fe3O4 -> FeO -> Fe2O3 -> Fe أو Fe -> FeSO4 -> Fe2O3 -> Fe3O4 -> Fe، المطلوب: تختار المادة والظرف لكل خطوة (هوا أو بخار مية على iron مسخّن لدرجة الاحمرار؛ H2 أو CO عند 400-700 C؛ التسخين في الهوا؛ CO أعلى من 700 C؛ dilute H2SO4؛ تسخين الـ FeSO4؛ CO عند 230-300 C) وتكتب المعادلات موزونة. الظروف هي اللي بتحدد الناتج.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["التحويلات بين الحديد وأكاسيده"]},"prereq_ids":["fe.blast-furnace-reduction","fe.oxide-fe3o4","fe.reaction-dilute-acids"],"in_chapter":true,"misconceptions":[{"id":"fe.conversions.mc1","label":"The same reagent always gives the same product whatever the temperature.","explanation":"No: the temperature decides the product. CO with $\\ce{Fe2O3}$ gives $\\ce{Fe3O4}$ at 230-300 °C, $\\ce{FeO}$ at 400-700 °C and iron above 700 °C; the higher the temperature, the more oxygen is removed.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، نفس المادة ممكن تدي نواتج مختلفة حسب درجة الحرارة: الـ CO مع الـ Fe2O3 بيدي Fe3O4 عند 230-300 C، ويدي FeO عند 400-700 C، ويوصل لـ iron عند أعلى من 700 C. كل ما الحرارة تعلى، الـ oxygen اللي بيتشال بيزيد.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.conversions.mc2","label":"Ignoring 'absence of air' / 'hot air' conditions.","explanation":"The condition written over the arrow is part of the step and can reverse the result: iron(II) oxalate heated in the absence of air gives $\\ce{FeO}$, but $\\ce{FeO}$ heated in hot air is oxidized to $\\ce{Fe2O3}$.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الظرف ده جزء من السهم ومينفعش تتجاهله: من غير هوا الـ FeO بيفضل FeO، إنما في الهوا السخن بيحصله oxidation ويبقى Fe2O3. يعني نتيجتين عكس بعض.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q6","section_title":"Write complete equations for the diagrams","section_path":["Transition Elements","Evaluation","Write complete equations for the diagrams"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q6","section_title":"Write complete equations for the diagrams","section_path":["Transition Elements","Evaluation","Write complete equations for the diagrams"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":24,"section_key":"ch1.iron.oxides","section_title":"Iron Oxides","section_path":["Transition Elements","Iron","Iron Oxides"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"fe.midrex-reduction","kind":"skill","title":"Reduction in the Midrex furnace","titles":{"en":"Reduction in the Midrex furnace"},"summary":"Natural gas (93% methane) is turned into water gas (CO + H2): 2CH4 + CO2 + H2O -> 3CO + 5H2; the gas mixture reduces the ore: 2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O. Role of natural gas: source of the reducing agents CO and H2.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ natural gas (93% methane) بيتحوّل لـ water gas (CO + H2): 2CH4 + CO2 + H2O -> 3CO + 5H2؛ وبعدين خليط الغازات ده بيختزل الـ ore: 2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O. دور الـ natural gas: إنه مصدر الـ reducing agents اللي هما CO والـ H2. المطلوب: إنك تكتب المعادلات دي وتقارن بالـ blast furnace.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الاختزال في فرن مدركس (الغاز الطبيعي)"]},"prereq_ids":["chem.natural-gas-methane","fe.blast-furnace-reduction"],"in_chapter":true,"misconceptions":[{"id":"fe.midrex-reduction.mc1","label":"Methane itself reduces the ore.","explanation":"No. Methane is not the reducing agent here. Natural gas (93% methane) is first turned into water gas, a mixture of $\\ce{CO}$ and $\\ce{H2}$, and these two gases reduce the iron ore to iron.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ methane نفسه مش هو اللي بيختزل الـ ore؛ اللي بيختزله هو الـ CO والـ H2 اللي بيطلعوا منه.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.midrex-reduction.mc2","label":"The Midrex furnace uses coke.","explanation":"No. The Midrex furnace uses no coke: natural gas is turned into $\\ce{CO}$ and $\\ce{H2}$, and this gas mixture reduces the ore. Coke belongs to the blast furnace.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ Midrex furnace مفيهوش coke؛ الـ CO والـ H2 اللي بيختزلوا الـ ore جايين من الـ natural gas، والـ coke ده بتاع الـ blast furnace.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q5","section_title":"Explain the role","section_path":["Transition Elements","Evaluation","Explain the role"],"relation":"based_on"}]},{"id":"fe.occurrence","kind":"concept","title":"Iron: abundance and suitability of iron ore","titles":{"en":"Iron: abundance and suitability of iron ore"},"summary":"Iron ($[Ar]\\ 4s^2\\ 3d^6$) is the most important metal in heavy industry and the 4th most abundant element in the crust after O, Si and Al (~5% by mass, increasing toward the core). It is found nearly pure (90%) only in meteorites; otherwise in ores: iron compounds (mostly oxides) mixed with impurities. Suitability of an ore depends on: its iron percentage, the composition of its impurities, and harmful elements present (S, P, As...).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ iron ([Ar] 4s2 3d6) هو أهم metal في الصناعات الثقيلة، ورابع عنصر في الوفرة في القشرة الأرضية بعد الـ O والـ Si والـ Al (حوالي 5% بالكتلة، والنسبة بتزيد واحنا رايحين ناحية لب الأرض). بيتلاقى شبه نقي (90%) في الـ meteorites تحديدًا؛ غير كده بيتلاقى في ores: iron compounds (أغلبها oxides) مخلوطة بشوائب. صلاحية الـ ore بتعتمد على تلات حاجات: نسبة الـ iron فيه، وتركيب الشوائب، ووجود عناصر ضارة (S, P, As...). المطلوب: تقول الحقايق دي والتلات عوامل.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الحديد في الطبيعة"]},"prereq_ids":["chem.elements-compounds-mixtures","found.percentages","te.first-series-elements"],"in_chapter":true,"misconceptions":[{"id":"fe.occurrence.mc1","label":"Iron is the most abundant element in the crust.","explanation":"No. Iron is the fourth most abundant element in the earth's crust, after oxygen, silicon and aluminum. Being the most important metal in heavy industry is about how much we use it, not how much of it there is.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ iron رابع عنصر في الوفرة في القشرة الأرضية، بعد الـ O والـ Si والـ Al. إنه أهم metal في الصناعات الثقيلة ده بيقول قد إيه بنستخدمه، مش قد إيه موجود منه.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.occurrence.mc2","label":"Iron is mined as pure metal.","explanation":"No. In the earth's crust iron is found in ores: iron compounds (mostly oxides) mixed with impurities, so it has to be extracted. Nearly pure iron (90%) is found only in meteorites.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الـ iron في القشرة الأرضية موجود في ores: iron compounds (أغلبها oxides) مخلوطة بشوائب، مش metal نقي. الـ iron شبه النقي (90%) مصدره الـ meteorites.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.occurrence.mc3","label":"Only the iron percentage decides if an ore is suitable.","explanation":"The iron percentage is one of three factors. Suitability also depends on the composition of the impurities and on harmful elements mixed with the ore, such as sulphur, phosphorus and arsenic.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"نسبة الـ iron عامل واحد من تلاتة. صلاحية الـ ore بتعتمد كمان على تركيب الشوائب وعلى العناصر الضارة اللي فيه زي الـ S والـ P والـ As.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron","section_title":"Iron","section_path":["Transition Elements","Iron"],"relation":"based_on"}]},{"id":"fe.ore-dressing","kind":"skill","title":"Ore dressing: crushing, sintering, concentrating","titles":{"en":"Ore dressing: crushing, sintering, concentrating"},"summary":"Ore dressing first improves the ore's physical and mechanical properties: crushing (a suitable size for easy reduction); sintering (gathering the fine particles from crushing and furnace cleaning into larger, uniform lumps usable in the furnace); concentration (raising iron % by removing impurities, using surface tension, magnetic or electric separation).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"أول حاجة الـ ore dressing بيعملها إنه يحسّن الخواص الفيزيائية والميكانيكية للـ ore: الـ crushing (عشان نوصل لحجم مناسب يخلّي الـ reduction سهل)؛ والـ sintering (بيلمّ الحبيبات الناعمة اللي طالعة من الـ crushing ومن تنضيف الفرن ويحوّلها لكتل أكبر ومتجانسة تنفع تتحط في الفرن)؛ والـ concentration (بيرفع نسبة الـ iron عن طريق شيل الشوائب، باستخدام الـ surface tension أو الـ magnetic separation أو الـ electric separation). المطلوب: تعرف كل خطوة بتتعمل ليه.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["تجهيز الخام: تكسير وتلبيد وتركيز"]},"prereq_ids":["chem.mixture-separation","fe.ores"],"in_chapter":true,"misconceptions":[{"id":"fe.ore-dressing.mc1","label":"Sintering means melting the ore.","explanation":"No. Sintering does not melt the ore into a liquid: it collects the fine particles from crushing and furnace cleaning into larger, homogeneous lumps that can be used in the furnace.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ sintering مش صهر. الـ ore مابيتحوّلش لسائل؛ اللي بيحصل إن الحبيبات الناعمة بتتجمّع في كتل أكبر ومتجانسة عشان تنفع تدخل الفرن.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.ore-dressing.mc2","label":"Concentration is a chemical change.","explanation":"Concentrating does not change the iron chemically: it removes most of the impurities chemically combined or mixed with the ore to raise the iron %. The mixed impurities are separated by surface tension or magnetic or electric separation; the chemical step of ore dressing is roasting.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الشوائب المخلوطة بالـ ore بتتفصل فصل فيزيائي (بالـ surface tension أو الـ magnetic separation أو الـ electric separation). الـ iron نفسه مابيتغيّرش، اللي بيتغيّر هو نسبته في الـ ore.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"fe.ores","kind":"concept","title":"Important iron ores","titles":{"en":"Important iron ores"},"summary":"Hematite Fe2O3 (iron(III) oxide; blood red; easily reduced; 50-60% Fe; Oases, Western Desert). Limonite 2Fe2O3.3H2O (hydrated iron(III) oxide; yellow; easily reduced; 20-60%; Oases). Magnetite Fe3O4 (magnetic iron oxide; black; magnetic; 45-70%; Eastern Desert). Siderite FeCO3 (iron(II) carbonate; yellowish grey; easily reduced; 30-42%).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ Hematite هو Fe2O3 (iron(III) oxide)، لونه أحمر دموي، سهل الاختزال، فيه 50-60% Fe، وموجود في الواحات والصحرا الغربية. الـ Limonite هو 2Fe2O3.3H2O (hydrated iron(III) oxide)، لونه أصفر، سهل الاختزال، فيه 20-60%، وموجود في الواحات. الـ Magnetite هو Fe3O4 (magnetic iron oxide)، لونه أسود، مغناطيسي، فيه 45-70%، وموجود في الصحرا الشرقية. الـ Siderite هو FeCO3 (iron(II) carbonate)، لونه رمادي مصفرّ، سهل الاختزال، فيه 30-42%. المطلوب: تربط كل ore باسمه الكيميائي والـ formula بتاعته ولونه وخاصيته ومكانه.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["خامات الحديد الأربعة"]},"prereq_ids":["chem.water-of-crystallization","fe.occurrence","pt.oxidation-number"],"in_chapter":true,"misconceptions":[{"id":"fe.ores.mc1","label":"Hematite and magnetite formulas swapped.","explanation":"They are swapped: hematite is $\\ce{Fe2O3}$ (iron(III) oxide) and magnetite is $\\ce{Fe3O4}$ (magnetic iron oxide). To tell them apart, magnetite is the black ore with magnetic properties; hematite is blood red.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، اتلخبطوا: الـ Hematite هو Fe2O3 (iron(III) oxide)، والـ Magnetite هو Fe3O4 (magnetic iron oxide). افتكرها كده: الـ Magnetite هو اللي مغناطيسي ولونه أسود.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.ores.mc2","label":"Siderite is an oxide.","explanation":"No. Siderite is iron(II) carbonate, $\\ce{FeCO3}$, not an oxide. That is why iron ores are described as iron compounds (mostly oxides) mixed with impurities.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ Siderite مش oxide، ده carbonate: FeCO3 (iron(II) carbonate).","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.ores.mc3","label":"Limonite is anhydrous.","explanation":"No. Limonite is hydrated iron(III) oxide, $\\ce{2Fe2O3.3H2O}$: water ($\\ce{3H2O}$) is part of its formula. Roasting drives this water out as vapour.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ Limonite مش anhydrous، ده hydrated: 2Fe2O3.3H2O، يعني فيه مية (3H2O) في تركيبه.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"fe.oxide-fe2o3","kind":"concept","title":"Iron(III) oxide Fe₂O₃","titles":{"en":"Iron(III) oxide Fe₂O₃"},"summary":"Preparation: an alkali added to an iron(III) salt solution precipitates reddish-brown Fe(OH)3 (FeCl3 + 3NH4OH -> Fe(OH)3 + 3NH4Cl), which above 200 °C gives Fe2O3 + H2O; or heating iron(II) sulphate: 2FeSO4 -> Fe2O3 + SO2 + SO3. Occurs naturally as hematite. Properties: insoluble in water; red pigment in paints; with hot concentrated acids gives iron(III) salts + water (Fe2O3 + 3H2SO4 -> Fe2(SO4)3 + 3H2O).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"التحضير: لما نضيف alkali لمحلول iron(III) salt بيترسّب Fe(OH)3 لونه بني محمر (FeCl3 + 3NH4OH -> Fe(OH)3 + 3NH4Cl)، ولما نسخّنه فوق 200 °C بيدّي Fe2O3 + H2O؛ أو بنسخّن الـ iron(II) sulphate: 2FeSO4 -> Fe2O3 + SO2 + SO3. وموجود في الطبيعة على شكل hematite. الخواص: مابيدوبش في المية، وبيستخدم كصبغة حمرا في البويات، ومع الـ hot concentrated acids بيدّي iron(III) salts ومية (Fe2O3 + 3H2SO4 -> Fe2(SO4)3 + 3H2O).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["أكسيد الحديد III (Fe₂O₃)"]},"prereq_ids":["chem.oxides","chem.reaction-types","fe.ores","pt.oxidation-number"],"in_chapter":true,"misconceptions":[{"id":"fe.oxide-fe2o3.mc1","label":"Heating FeSO4 gives FeO, or gives only SO2.","explanation":"No. Heating iron(II) sulphate gives iron(III) oxide, not FeO, and two gases, not one: $\\ce{2FeSO4 -> Fe2O3 + SO2 + SO3}$. So the products are $\\ce{Fe2O3}$, $\\ce{SO2}$ and $\\ce{SO3}$.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، تسخين الـ FeSO4 بيدّي Fe2O3 + SO2 + SO3، يعني تلات نواتج مش FeO ولا SO2 لوحده.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.oxide-fe2o3.mc2","label":"Fe2O3 reacts with cold dilute acids like FeO.","explanation":"Not like FeO. The book reacts FeO with dilute sulphuric acid, but $\\ce{Fe2O3}$ with hot concentrated mineral acids, giving iron(III) salts and water: $\\ce{Fe2O3 + 3H2SO4 -> Fe2(SO4)3 + 3H2O}$.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الكتاب بيفاعل الـ Fe2O3 مع hot concentrated acids، مش cold dilute acids زي الـ FeO.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"relation":"based_on"}]},{"id":"fe.oxide-fe3o4","kind":"concept","title":"Magnetic iron oxide Fe₃O₄","titles":{"en":"Magnetic iron oxide Fe₃O₄"},"summary":"Black magnetic oxide; a mixed iron(II)/iron(III) oxide, natural magnetite. Preparation: hot air or steam on red-hot iron; reducing Fe2O3 with CO at 230-300 C (3Fe2O3 + CO -> 2Fe3O4 + CO2). Properties: strong magnet; with hot concentrated acids gives iron(II) + iron(III) salts (Fe3O4 + 4H2SO4 -> FeSO4 + Fe2(SO4)3 + 4H2O), proving it is a mixed oxide; heated in air it is oxidized to Fe2O3 (2Fe3O4 + 1/2 O2 -> 3Fe2O3).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ oxide الأسود الـ magnetic؛ mixed oxide فيه iron(II) و iron(III) مع بعض، واسمه في الطبيعة magnetite. التحضير: هوا سخن أو بخار مية على iron سخن لدرجة الاحمرار؛ أو اختزال الـ Fe2O3 بالـ CO عند 230-300 C (3Fe2O3 + CO -> 2Fe3O4 + CO2). الخواص: strong magnet؛ ومع الـ hot concentrated acids بيدّي iron(II) salts و iron(III) salts (Fe3O4 + 4H2SO4 -> FeSO4 + Fe2(SO4)3 + 4H2O)، وده الدليل إنه mixed oxide؛ ولو اتسخّن في الهوا بيتأكسد ويتحوّل لـ Fe2O3 (2Fe3O4 + 1/2 O2 -> 3Fe2O3).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["أكسيد الحديد المغناطيسي (Fe₃O₄)"]},"prereq_ids":["fe.oxide-fe2o3","fe.oxide-feo","fe.reactions-air-steam"],"in_chapter":true,"misconceptions":[{"id":"fe.oxide-fe3o4.mc1","label":"Fe3O4 is a single oxide that gives one salt.","explanation":"No. $\\ce{Fe3O4}$ is a mixed oxide of iron(II) and iron(III), so with hot concentrated acids it gives two salts: $\\ce{Fe3O4 + 4H2SO4 -> FeSO4 + Fe2(SO4)3 + 4H2O}$. These two salts are the proof that it is a mixed oxide.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ Fe3O4 مش oxide واحد بسيط: هو mixed oxide (FeO + Fe2O3)، فمع الـ hot concentrated acids بيدّي ملحين: iron(II) salt من جزء الـ FeO و iron(III) salt من جزء الـ Fe2O3.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.oxide-fe3o4.mc2","label":"Reducing Fe2O3 with CO always gives iron.","explanation":"Not always: the temperature decides the product. At 230–300 °C, $\\ce{3Fe2O3 + CO -> 2Fe3O4 + CO2}$, so you get the black oxide $\\ce{Fe3O4}$; iron forms at temperatures higher than 700 °C, as in the blast furnace.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، درجة الحرارة هي اللي بتحدد: عند 230-300 C الناتج Fe3O4، وعشان يطلع iron لازم أعلى من 700 C.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":24,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"relation":"based_on"}]},{"id":"fe.oxide-feo","kind":"concept","title":"Iron(II) oxide FeO","titles":{"en":"Iron(II) oxide FeO"},"summary":"Preparation: heating iron(II) oxalate in the absence of air -> FeO + CO + CO2; reducing higher oxides with H2 or CO at 400-700 C (Fe2O3 + H2 -> 2FeO + H2O; Fe3O4 + H2 -> 3FeO + H2O). Properties: black powder, insoluble in water; easily oxidized in hot air (4FeO + O2 -> 2Fe2O3); with dilute mineral acids gives iron(II) salt + water (FeO + H2SO4 -> FeSO4 + H2O).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"التحضير: بنسخّن الـ iron(II) oxalate في غياب الهوا -> FeO + CO + CO2، أو بنعمل reduction للـ higher oxides بالـ H2 أو الـ CO عند 400-700 C (Fe2O3 + H2 -> 2FeO + H2O؛ Fe3O4 + H2 -> 3FeO + H2O). الخواص: مسحوق أسود مابيدوبش في المية، وبيحصله oxidation بسهولة في الهوا السخن (4FeO + O2 -> 2Fe2O3)، ومع الـ dilute mineral acids بيدّي iron(II) salt ومية (FeO + H2SO4 -> FeSO4 + H2O).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["أكسيد الحديد II (FeO)"]},"prereq_ids":["chem.oxides","chem.reaction-types","pt.oxidation-number","redox.basic"],"in_chapter":true,"misconceptions":[{"id":"fe.oxide-feo.mc1","label":"Heating iron(II) oxalate in air gives FeO.","explanation":"No: the oxalate must be heated in the absence of air. FeO is easily oxidized in hot air ($\\ce{4FeO + O2 -> 2Fe2O3}$), so heating in air would not leave FeO.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، لازم الهوا يكون مش موجود: الـ FeO بيحصله oxidation بسهولة في الهوا السخن.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.oxide-feo.mc2","label":"FeO + dilute acid gives an iron(III) salt.","explanation":"No. FeO reacts with dilute mineral acids without any oxidation: iron stays +2, so the product is an iron(II) salt and water, e.g. $\\ce{FeO + H2SO4 -> FeSO4 + H2O}$.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، مفيش oxidation بيحصل هنا: الـ iron في الـ FeO بيبقى +2 وبيفضل +2، فالـ FeO مع الـ dilute acid بيدّي iron(II) salt ومية (زي FeSO4).","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.oxide-feo.mc3","label":"FeO is red.","explanation":"No. FeO is a black powder. The red oxide is $\\ce{Fe2O3}$: hematite is blood red, and $\\ce{Fe2O3}$ is used as a red pigment in paints.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ FeO مسحوق أسود. الـ oxide الأحمر هو الـ Fe2O3.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"relation":"based_on"}]},{"id":"fe.passivity","kind":"concept","title":"Passivity of iron","titles":{"en":"Passivity of iron"},"summary":"Concentrated nitric acid makes iron passive: a thin oxide layer forms and protects the metal from further reaction. The layer is removed by rubbing (abrasion) or by dilute HCl.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ concentrated nitric acid بيخلّي الـ iron يحصله passivity: بتتكوّن طبقة رقيقة من الـ oxide على السطح بتحمي الـ metal من إنه يكمّل تفاعل. والطبقة دي بتتشال بالـ abrasion (الحكّ) أو بالـ dilute HCl. المطلوب: تشرح الـ passivity وإزاي تشيلها.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["خمول الحديد في حمض النيتريك المركز"]},"prereq_ids":["fe.reaction-dilute-acids","te.chromium-oxide-layer"],"in_chapter":true,"misconceptions":[{"id":"fe.passivity.mc1","label":"Concentrated HNO3 dissolves iron quickly.","explanation":"No. Concentrated $\\ce{HNO3}$ forms a thin oxide layer on the surface of iron, and this layer protects the metal from further reaction. That is passivity: the iron stops reacting instead of dissolving.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ concentrated $\\ce{HNO3}$ مش بيدوّب الـ iron بسرعة. هو بيكوّن طبقة رقيقة من الـ oxide على السطح، والطبقة دي بتغطي الـ iron وبتمنع إنه يكمّل تفاعل، وده اللي اسمه passivity.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.passivity.mc2","label":"Passivity is permanent.","explanation":"No. The protecting oxide is a thin surface layer: removing it by abrasion or with dilute HCl exposes fresh iron, which can react again.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ passivity مش دايمة. الطبقة على السطح تحديدًا، ولو شلتها بالـ abrasion أو بالـ dilute HCl، الـ iron الجديد اللي تحتها بيرجع يتفاعل تاني.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"}]},{"id":"fe.physical-properties","kind":"concept","title":"Physical properties of iron","titles":{"en":"Physical properties of iron"},"summary":"Pure iron has no industrial importance: relatively soft, malleable, ductile, magnetic, melts at 1538 C, density 7.87 g/cm3. Its physical properties depend on its purity and on its impurities, so many steels and iron alloys with specific properties are made.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ iron النقي مالوش أهمية صناعية: هو relatively soft، و malleable و ductile و magnetic، وبينصهر عند 1538 C، والـ density بتاعته 7.87 g/cm3. الـ physical properties بتاعته بتعتمد على درجة نقاوته وعلى الشوائب اللي فيه، وعشان كده بيتعمل منه steels و iron alloys كتير بخواص محددة. المطلوب: تشرح ليه الـ iron النقي مش بيتستخدم، وليه الـ alloys هي اللي بتتستخدم.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["خواص الحديد الفيزيائية"]},"prereq_ids":["alloy.interstitial","chem.metal-properties","phys.density"],"in_chapter":true,"misconceptions":[{"id":"fe.physical-properties.mc1","label":"Pure iron is very hard.","explanation":"No. Pure iron is relatively soft, as well as malleable and ductile. That is why pure iron has no industrial importance and iron is used as steels and alloys with the properties needed.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ iron النقي relatively soft، يعني الـ hardness بتاعته قليلة.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.physical-properties.mc2","label":"Pure iron is the most useful form of iron.","explanation":"The opposite: pure iron has no industrial importance because it is relatively soft. What industry uses are steels and iron alloys, made with specific properties.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"بالعكس، الـ iron النقي مالوش أهمية صناعية عشان هو relatively soft. اللي بيتستخدم فعلًا هو الـ steels والـ iron alloys اللي بتتعمل بخواص محددة.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.properties","section_title":"Properties of Iron","section_path":["Transition Elements","Iron","Properties of Iron"],"relation":"based_on"}]},{"id":"fe.reaction-conc-sulfuric","kind":"concept","title":"Iron with hot concentrated sulphuric acid","titles":{"en":"Iron with hot concentrated sulphuric acid"},"summary":"3Fe + 8H2SO4 (conc., hot) -> FeSO4 + Fe2(SO4)3 + 4SO2 + 8H2O: the hot concentrated acid oxidizes iron to a mixture of iron(II) and iron(III) sulphates and gives SO2 (not H2).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"3Fe + 8H2SO4 (conc., hot) -> FeSO4 + Fe2(SO4)3 + 4SO2 + 8H2O: الـ concentrated acid السخن بيعمل oxidation للـ iron ويدّي خليط من iron(II) sulphate و iron(III) sulphate، وبيطلّع SO2 (مش H2). المطلوب: إنك تكتب المعادلة موزونة وتقارنها بتفاعل الـ dilute acid.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الحديد مع حمض الكبريتيك المركز الساخن"]},"prereq_ids":["chem.solution-concentration","fe.reaction-dilute-acids"],"in_chapter":true,"misconceptions":[{"id":"fe.reaction-conc-sulfuric.mc1","label":"Concentrated H2SO4 gives H2 like the dilute acid.","explanation":"No. Hot concentrated $\\ce{H2SO4}$ oxidizes iron and gives sulphur dioxide, not hydrogen: $\\ce{3Fe + 8H2SO4 -> FeSO4 + Fe2(SO4)3 + 4SO2 + 8H2O}$. Hydrogen comes from iron with the dilute acid.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ concentrated H2SO4 السخن بيعمل oxidation للـ iron، فالغاز اللي بيطلع SO2 مش H2. الـ H2 ده بيطلع مع الـ dilute acid.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.reaction-conc-sulfuric.mc2","label":"Only iron(III) sulphate forms.","explanation":"No. The book's products are a mixture of iron(II) sulphate and iron(III) sulphate, $\\ce{FeSO4}$ and $\\ce{Fe2(SO4)3}$, together with $\\ce{SO2}$ and water; both sulphates must appear in the equation.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش كده: نواتج الكتاب خليط من iron (II) sulphate و iron (III) sulphate، FeSO4 و Fe2(SO4)3، ولازم تكتب الاتنين في المعادلة.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"fe.reaction-dilute-acids","kind":"concept","title":"Iron with dilute acids","titles":{"en":"Iron with dilute acids"},"summary":"Fe + dil. H2SO4 -> FeSO4 + H2; Fe + 2HCl -> FeCl2 + H2. Iron(II), not iron(III), salts form because the hydrogen produced reduces iron(III) to iron(II) (the book's reason).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"Fe + dil. H2SO4 -> FeSO4 + H2، وكمان Fe + 2HCl -> FeCl2 + H2. اللي بيتكوّن iron(II) salts مش iron(III) salts، عشان الـ hydrogen اللي بيطلع من التفاعل بيختزل الـ iron(III) لـ iron(II) (ده سبب الكتاب). المطلوب: تكتب المعادلتين وتقول السبب.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الحديد مع الأحماض المخففة: ليه Fe²⁺ مش Fe³⁺؟"]},"prereq_ids":["acid.metal-acid-reaction","chem.solution-concentration","redox.electronic"],"in_chapter":true,"misconceptions":[{"id":"fe.reaction-dilute-acids.mc1","label":"Fe + HCl gives FeCl3 because Fe + Cl2 gives FeCl3.","explanation":"No. Chlorine is a strong oxidizing agent and takes iron to +3, with no hydrogen present to bring it back. With dilute HCl, hydrogen is produced and reduces iron(III) to iron(II), so the product is $\\ce{FeCl2}$.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ Cl2 oxidizing agent قوي فبيوصّل الـ iron لـ iron(III)، ومفيش hydrogen يرجّعه. إنما مع الـ HCl بيتكوّن hydrogen، والـ hydrogen ده بيختزل الـ iron(III) لـ iron(II)، فالناتج FeCl2.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.reaction-dilute-acids.mc2","label":"Iron does not react with dilute acids.","explanation":"It does: iron dissolves in dilute mineral acids. Iron is above hydrogen in the activity series, so it displaces hydrogen, giving an iron(II) salt and hydrogen gas, e.g. $\\ce{Fe + H2SO4 -> FeSO4 + H2}$.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش صح: الـ iron بيدوب في الـ dilute mineral acids. هو فوق الـ hydrogen في الـ activity series، فبياخد مكانه في الـ acid ويطلع hydrogen gas ويتكوّن iron(II) salt.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"}]},{"id":"fe.reactions-air-steam","kind":"concept","title":"Effect of air and water vapour","titles":{"en":"Effect of air and water vapour"},"summary":"Red-hot iron with dry air or oxygen gives magnetic iron oxide: 3Fe + 2O2 -> Fe3O4. Red-hot iron (500 °C) with steam gives magnetic iron oxide and hydrogen: 3Fe + 4H2O -> Fe3O4 + 4H2.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ iron وهو أحمر من السخونية لو اتفاعل مع هوا جاف أو oxygen بيدّي magnetic iron oxide: 3Fe + 2O2 -> Fe3O4. ولو الـ iron الأحمر من السخونية (500 °C) اتفاعل مع steam بيدّي magnetic iron oxide و hydrogen: 3Fe + 4H2O -> Fe3O4 + 4H2. المطلوب: إنك تكتب المعادلتين وتسمّي الناتج.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الحديد مع الهوا وبخار الماء"]},"prereq_ids":["chem.equation-reading","fe.ores","redox.basic"],"in_chapter":true,"misconceptions":[{"id":"fe.reactions-air-steam.mc1","label":"Heated iron + oxygen gives Fe2O3 here.","explanation":"No. Red-hot iron with dry air or oxygen gives magnetic iron oxide, $\\ce{Fe3O4}$: $\\ce{3Fe + 2O2 -> Fe3O4}$. $\\ce{Fe2O3}$ is not the product of this reaction.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ iron الأحمر من السخونية مع الـ oxygen هنا بيدّي Fe3O4، اللي هو magnetic iron oxide، مش Fe2O3.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.reactions-air-steam.mc2","label":"Iron + steam gives Fe(OH)2 or Fe2O3.","explanation":"No. Red-hot iron (500 °C) with water vapour gives magnetic iron oxide and hydrogen gas: $\\ce{3Fe + 4H2O -> Fe3O4 + 4H2}$. The hydrogen leaves as a gas, so no hydroxide is left behind.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش كده: الـ hydrogen بيطلع على هيئة gas، فمفيش hydroxide بيفضل. الناتج الصلب هنا برضه هو Fe3O4، الـ magnetic iron oxide الأسود، ومعاه hydrogen gas: 3Fe + 4H2O -> Fe3O4 + 4H2.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"fe.reactions-nonmetals","kind":"concept","title":"Iron with non-metals: chlorine and sulphur","titles":{"en":"Iron with non-metals: chlorine and sulphur"},"summary":"Iron with chlorine gives iron(III) chloride: 2Fe + 3Cl2 -> 2FeCl3; with sulphur gives iron(II) sulphide: Fe + S -> FeS.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ iron مع الـ chlorine بيدّي iron(III) chloride: 2Fe + 3Cl2 -> 2FeCl3؛ ومع الـ sulphur بيدّي iron(II) sulphide: Fe + S -> FeS. المطلوب: إنك تكتب المعادلتين وتقول الـ oxidation state بتاع الـ iron في كل ناتج.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الحديد مع الكلور والكبريت"]},"prereq_ids":["chem.equation-reading","pt.oxidation-number"],"in_chapter":true,"misconceptions":[{"id":"fe.reactions-nonmetals.mc1","label":"Fe + Cl2 gives FeCl2.","explanation":"No. Chlorine is a strong oxidizing agent, so it takes iron to +3 and gives iron(III) chloride: $\\ce{2Fe + 3Cl2 -> 2FeCl3}$. $\\ce{FeCl2}$ forms from iron with dilute HCl, not with chlorine gas.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ chlorine oxidizing agent قوي، فبياخد الـ iron لـ +3 ويدّي FeCl3، يعني iron (III) chloride. الـ FeCl2 ده ناتج الـ iron مع الـ dilute HCl، مش مع الـ chlorine gas.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.reactions-nonmetals.mc2","label":"Fe + S gives Fe2S3 or FeSO4.","explanation":"No. Sulphur is a weaker oxidizing agent than chlorine, so iron stops at +2 and gives iron(II) sulphide: $\\ce{Fe + S -> FeS}$. No oxygen takes part, so no sulphate forms.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش كده: الـ sulphur oxidizing agent أضعف من الـ chlorine، فالـ iron بيقف عند +2 ويدّي FeS، يعني iron (II) sulphide. ومفيش oxygen داخل في التفاعل، فمفيش sulphate يتكوّن.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"relation":"based_on"}]},{"id":"fe.roasting","kind":"skill","title":"Roasting of iron ore","titles":{"en":"Roasting of iron ore"},"summary":"Roasting = strong heating of the ore in air (the chemical part of ore dressing) to: (a) dry it and expel moisture, raising the iron % (2Fe2O3.3H2O -> 2Fe2O3 + 3H2O); on siderite the rise shows over the whole route, FeCO3 -> FeO + CO2 then 2FeO + 1/2 O2 -> Fe2O3 (the FeO -> Fe2O3 step on its own lowers %Fe, but FeCO3 -> Fe2O3 raises it overall); (b) oxidize impurities such as S and P (S + O2 -> SO2; 4P + 5O2 -> 2P2O5).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ roasting يعني تسخين الـ ore تسخين شديد في الهوا، وده الجزء الكيميائي من الـ ore dressing. ليه هدفين: (a) تجفيف الـ ore وطرد الرطوبة عشان نسبة الـ iron تزيد (2Fe2O3.3H2O -> 2Fe2O3 + 3H2O)؛ وفي الـ siderite الزيادة بتبان على المسار كله: FeCO3 -> FeO + CO2 وبعدين 2FeO + 1/2 O2 -> Fe2O3 (خطوة FeO -> Fe2O3 لوحدها بتقلّل نسبة الـ iron، لكن من FeCO3 لـ Fe2O3 النسبة بتزيد في المجمل)؛ (b) أكسدة شوائب زي الـ S والـ P (S + O2 -> SO2؛ 4P + 5O2 -> 2P2O5). المطلوب: إنك تكتب المعادلات دي وتشرح ليه نسبة الـ iron بتزيد في المجمل (الكتاب بيدي 48.5% للـ FeCO3 النقي اللي في الـ siderite، و69.6% للـ Fe2O3).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["التحميص"]},"prereq_ids":["chem.equation-reading","chem.reaction-types","fe.ore-dressing","redox.basic","stoich.mass-percentage"],"in_chapter":true,"misconceptions":[{"id":"fe.roasting.mc1","label":"Roasting reduces the ore.","explanation":"No. Roasting is strong heating of the ore in air, so oxygen is added, not removed: it dries the ore, decomposes it (e.g. $\\ce{FeCO3 -> FeO + CO2}$) and oxidizes FeO, S and P. Reduction to iron comes later, in the blast or Midrex furnace.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ roasting تسخين في الهوا، فاللي بيحصل فيه thermal decomposition و oxidation، مش reduction.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.roasting.mc2","label":"Roasting removes S and P by melting them.","explanation":"No. Roasting does not melt sulphur and phosphorus out: it oxidizes them with the oxygen of the air, $\\ce{S + O2 -> SO2}$ and $\\ce{4P + 5O2 -> 2P2O5}$. This is the second purpose of roasting.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ roasting مش بيدوّب الـ S والـ P؛ هو بيعملهم oxidation: بيتفاعلوا مع الـ oxygen اللي في الهوا.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"fe.steel-production","kind":"skill","title":"Iron production and steel","titles":{"en":"Iron production and steel"},"summary":"After reduction (blast furnace or Midrex), the third stage produces types of iron such as cast iron and steel. Steel making rests on two processes: removing impurities from the furnace iron, and adding elements to give the properties needed. Steel furnaces: oxygen converters, open-hearth furnace, electric furnace (their internals are not in the book).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"بعد الـ reduction (في الـ blast furnace أو الـ Midrex)، المرحلة التالتة بتطلّع أنواع من الـ iron زي الـ cast iron والـ steel. صناعة الـ steel قايمة على عمليتين: شيل الشوائب من الـ iron اللي طالع من الأفران، وإضافة عناصر عشان تديله الخواص المطلوبة. أفران الـ steel هي: الـ oxygen converters، والـ open-hearth furnace، والـ electric furnace (اللي جواها مش في الكتاب). المطلوب: تسمّي العمليتين والتلات أفران.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["إنتاج الصلب"]},"prereq_ids":["fe.blast-furnace-reduction"],"in_chapter":true,"misconceptions":[{"id":"fe.steel-production.mc1","label":"Steel is pure iron.","explanation":"No. Steel is an alloy of iron, not pure iron: it is made from furnace iron by removing impurities and then adding elements, such as carbon, to give it the properties needed for industry.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ steel مش iron نقي. ده iron اتضافله عناصر بقصد، زي الـ carbon، عشان ياخد الخواص المطلوبة.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"fe.steel-production.mc2","label":"Steel comes straight out of the blast furnace.","explanation":"No. The blast furnace (or the Midrex furnace) produces iron, not steel. Steel is made from this iron afterwards, in steel furnaces, by removing impurities and adding elements to give the properties needed.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ blast furnace (أو الـ Midrex) بيدّي iron، مش steel. الـ steel بيتعمل من الـ iron ده بعد كده في أفران الـ steel، بشيل الشوائب وإضافة عناصر.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.production","section_title":"Iron Production (steel)","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Iron Production (steel)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys","section_title":"Alloys","section_path":["Transition Elements","Alloys"],"relation":"based_on"}]},{"id":"found.four-operations","kind":"foundation","title":"The four arithmetic operations","titles":{"en":"The four arithmetic operations"},"summary":"Addition, subtraction, multiplication and division.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الجمع والطرح والضرب والقسمة.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["العمليات الحسابية الأربع"]},"prereq_ids":[],"in_chapter":true,"misconceptions":[]},{"id":"found.fractions-decimals","kind":"foundation","title":"Fractions and decimals","titles":{"en":"Fractions and decimals"},"summary":"Simple fractions and decimal numbers.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الكسور البسيطة والأرقام العشرية.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الكسور والأعداد العشرية"]},"prereq_ids":[],"in_chapter":true,"misconceptions":[]},{"id":"found.integers","kind":"foundation","title":"Positive and negative numbers","titles":{"en":"Positive and negative numbers"},"summary":"Signed integers and adding them.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ signed integers، يعني الأعداد الصحيحة اللي ليها إشارة (positive أو negative)، وإزاي نجمعها.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الأعداد الموجبة والسالبة"]},"prereq_ids":[],"in_chapter":true,"misconceptions":[]},{"id":"found.latin-letters","kind":"foundation","title":"Reading Latin letters","titles":{"en":"Reading Latin letters"},"summary":"Recognizing English letters used in chemical symbols and terms.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"إنك تتعرف على الحروف الإنجليزي اللي بتيجي في الـ chemical symbols وفي المصطلحات العلمية.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["قراءة الحروف الإنجليزي"]},"prereq_ids":[],"in_chapter":true,"misconceptions":[]},{"id":"found.percentages","kind":"foundation","title":"Percentages","titles":{"en":"Percentages"},"summary":"Reading and computing percentages.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"إزاي تقرا النسبة المئوية وإزاي تحسبها.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["النسبة المئوية"]},"prereq_ids":[],"in_chapter":true,"misconceptions":[]},{"id":"found.reading-arabic","kind":"foundation","title":"Reading and writing Arabic","titles":{"en":"Reading and writing Arabic"},"summary":"Basic literacy in Arabic.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"أساسيات القراية والكتابة بالعربي.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["القراءة والكتابة بالعربي"]},"prereq_ids":[],"in_chapter":true,"misconceptions":[]},{"id":"found.tables-graphs","kind":"foundation","title":"Reading tables and graphs","titles":{"en":"Reading tables and graphs"},"summary":"Reading values from a table and from a simple line graph with labelled axes.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"إزاي تطلّع قيمة من جدول، ومن رسم بياني خطّي بسيط محاوره عليها أسماء واضحة.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["قراءة الجداول والرسوم البيانية"]},"prereq_ids":[],"in_chapter":true,"misconceptions":[]},{"id":"found.whole-numbers","kind":"foundation","title":"Counting and whole numbers","titles":{"en":"Counting and whole numbers"},"summary":"Counting, comparing and ordering whole numbers.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"العدّ، وإنك تقارن الأعداد الصحيحة ببعض وترتبها.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["العد والأعداد"]},"prereq_ids":[],"in_chapter":true,"misconceptions":[]},{"id":"kin.activation-energy","kind":"concept","title":"Activation energy and energy profile","titles":{"en":"Activation energy and energy profile"},"summary":"Reacting particles must collide with at least a minimum energy (activation energy) to break bonds and react; an energy profile plots potential energy against reaction progress, with a hump for activation energy and the reactant/product levels showing the net energy change. Formally taught in Ch.3 (Chemical Equilibrium) of the same book, after this chapter, so students meet it here first.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الجزيئات اللي هتتفاعل لازم تتصادم بـ energy مش أقل من حد أدنى (الـ activation energy) عشان الـ bonds تتكسر ويحصل reaction. والـ energy profile بيرسم الـ potential energy قصاد الـ progress of reaction: فيه حدبة بتمثل الـ activation energy، ومستوى الـ reactants والـ products بيوضح التغيير الصافي في الـ energy. الموضوع ده بيتدرس رسمي في الفصل التالت (Chemical Equilibrium) من نفس الكتاب، بعد الفصل ده، فالطالب بيقابله هنا الأول.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["طاقة التنشيط ومنحنى الطاقة"]},"prereq_ids":["chem.bond-breaking-energy","found.tables-graphs"],"in_chapter":true,"misconceptions":[{"id":"kin.activation-energy.mc1","label":"Activation energy is the energy released by the reaction.","explanation":"No. The energy released by the reaction is the net drop from the reactants' level to the products' level. Activation energy is the climb from the reactants up to the top of the hump: the minimum energy colliding particles need in order to react.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ energy اللي الـ reaction بيطلّعها دي الـ net energy released: النزلة من الـ reactants للـ products. إنما الـ activation energy هي الطلعة من الـ reactants لفوق لحد قمة الحدبة، يعني أقل energy لازم الجزيء يكسبها عشان يتفاعل وقت التصادم.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":61,"page_to":62,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"phys.density","kind":"concept","title":"Density","titles":{"en":"Density"},"summary":"Density = mass / volume; packing more mass into the same volume means higher density.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ Density = mass / volume، يعني لو حشرت mass أكتر في نفس الـ volume، الـ density بتزيد.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الكثافة"]},"prereq_ids":["phys.mass-volume"],"in_chapter":true,"misconceptions":[]},{"id":"phys.electric-charges","kind":"concept","title":"Electric charges attract and repel","titles":{"en":"Electric charges attract and repel"},"summary":"There are positive and negative charges; like charges repel and unlike charges attract, more strongly when closer.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"فيه charges نوعين: positive و negative. الـ like charges بتتنافر، والـ unlike charges بتتجاذب، وبيبقى ده أقوى لما يكونوا أقرب لبعض.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الشحنات: تجاذب وتنافر"]},"prereq_ids":["found.reading-arabic"],"in_chapter":true,"misconceptions":[]},{"id":"phys.electric-current","kind":"concept","title":"Electric current","titles":{"en":"Electric current"},"summary":"An electric current is a flow of charges through a conductor or solution, driven by a source such as a battery.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ electric current هو charges بتسري جوه conductor أو solution، واللي بيزقها مصدر زي البطارية.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["التيار الكهربي"]},"prereq_ids":["phys.electric-charges"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":66,"page_to":66,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":84,"page_to":84,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"phys.em-spectrum","kind":"concept","title":"Electromagnetic radiation (UV, X-rays, gamma)","titles":{"en":"Electromagnetic radiation (UV, X-rays, gamma)"},"summary":"Light is one member of a family of electromagnetic rays, in order: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays. From radio waves to gamma rays the frequency and energy rise and the wavelength falls; X-rays and gamma rays are highly penetrating (gamma the most), so they are used to see inside objects (X-ray screens, checking welds) and to treat tumours.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الضوء واحد من عيلة الـ electromagnetic rays، وترتيبها كده: radio waves، microwaves، infrared، visible light، ultraviolet، X-rays، gamma rays. وإنت ماشي من الـ radio waves لحد الـ gamma rays، الـ frequency والـ energy بيزيدوا والـ wavelength بتقل. والـ X-rays والـ gamma rays عندهم penetrating power عالية (والـ gamma أعلاهم)، عشان كده بنستخدمهم عشان نشوف جوه الأجسام (شاشات الـ X-ray وفحص اللحامات) وفي علاج الأورام.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الأشعة الكهرومغناطيسية (UV و X وجاما)"]},"prereq_ids":["phys.waves-light"],"in_chapter":true,"misconceptions":[{"id":"phys.em-spectrum.mc1","label":"Gamma rays are particles like alpha and beta.","explanation":"No. Gamma rays are not particles like alpha and beta. They are electromagnetic rays, in the same family as light, at its high-energy end, and they have a very high penetrating power.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ gamma rays مش particles؛ دي electromagnetic rays زيها زي الضوء.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"phys.em-spectrum.mc2","label":"Only visible light is electromagnetic radiation.","explanation":"No. Visible light is one member of the electromagnetic family; radio waves, microwaves, infrared, ultraviolet, X-rays and gamma rays are electromagnetic radiation too. Visible light is simply the part our eyes can see.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الـ visible light عضو واحد من عيلة الـ electromagnetic radiation؛ الـ radio waves والـ microwaves والـ infrared والـ ultraviolet والـ X-rays والـ gamma rays منها هي كمان. الفرق إن عينينا بتشوف الجزء الـ visible لوحده.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}]},{"id":"phys.magnetic-field","kind":"concept","title":"Magnets and magnetic fields","titles":{"en":"Magnets and magnetic fields"},"summary":"A magnet has a magnetic field around it that attracts some materials (like iron) and attracts or repels other magnets; like poles repel, unlike attract.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ magnet حواليه magnetic field بيجذب مواد معيّنة (زي الـ iron)، وبيجذب أو بيطرد magnets تانية: الـ like poles بتتنافر، والـ unlike poles بتتجاذب.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["المغناطيس والمجال المغناطيسي"]},"prereq_ids":["found.reading-arabic"],"in_chapter":true,"misconceptions":[{"id":"phys.magnetic-field.mc1","label":"Magnets attract all metals.","explanation":"No. A magnet strongly attracts iron, cobalt and nickel (and steel, which is mostly iron), but other metals such as copper, aluminum and gold are not noticeably attracted by an ordinary magnet.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ magnet بيجذب بقوة الـ iron والـ cobalt والـ nickel (والـ steel عشان أغلبه iron). أما الـ copper والـ aluminum والـ gold فهي metals برضه، لكن الـ magnet العادي مش بيشدها بشكل ملحوظ.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}]},{"id":"phys.mass-volume","kind":"foundation","title":"Mass and volume","titles":{"en":"Mass and volume"},"summary":"Mass is the amount of matter (g, kg); volume is the space it takes (cm3, L). You measured both in primary school.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ mass هي كمية المادة (g, kg)، والـ volume هو الحيّز اللي المادة بتشغله (cm3, L). ده قياس إنت اتعلمته في المرحلة الابتدائية.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الكتلة والحجم"]},"prereq_ids":[],"in_chapter":true,"misconceptions":[]},{"id":"phys.radioactivity-gamma","kind":"concept","title":"Radioactivity and gamma rays","titles":{"en":"Radioactivity and gamma rays"},"summary":"Some isotopes have unstable nuclei that decay and emit radiation; gamma rays are high-energy electromagnetic rays with high penetrating power.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"فيه isotopes الـ nuclei بتاعتها unstable، فبتعمل decay وبتطلّع radiation. والـ gamma rays هي electromagnetic rays طاقتها عالية جدًا، وليها high penetrating power.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["النشاط الإشعاعي وأشعة جاما"]},"prereq_ids":["atom.isotopes","phys.em-spectrum"],"in_chapter":true,"misconceptions":[{"id":"phys.radioactivity-gamma.mc1","label":"Anything exposed to gamma rays becomes radioactive.","explanation":"No. Gamma rays pass through the object and leave; they do not put a radioactive isotope inside it, so the object does not become radioactive. The unstable nuclei stay in the source that gives out the rays.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ gamma rays بتعدّي من الجسم وتمشي، ومش بتحط جواه radioactive isotope، فهو مش بيبقى radioactive. الـ radioactive isotope موجود في المصدر نفسه.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}]},{"id":"phys.states-melting-boiling","kind":"concept","title":"States of matter, melting and boiling points","titles":{"en":"States of matter, melting and boiling points"},"summary":"Matter is solid, liquid or gas; the melting point and boiling point are the temperatures at which a substance changes state; stronger forces between particles mean higher values.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ matter بتبقى solid أو liquid أو gas. الـ melting point والـ boiling point هما درجات الحرارة اللي عندها المادة بتغيّر حالتها. ولما الـ forces بين الـ particles تكون أقوى، القيم دي بتطلع أعلى.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["حالات المادة والانصهار والغليان"]},"prereq_ids":["found.whole-numbers","sci.matter-particles"],"in_chapter":true,"misconceptions":[]},{"id":"phys.waves-light","kind":"concept","title":"Light and waves","titles":{"en":"Light and waves"},"summary":"Light travels as waves carrying energy; waves differ in wavelength and frequency.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الضوء بيتنقل على شكل waves شايلة energy، والـ waves دي بتختلف عن بعض في الـ wavelength والـ frequency.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الضوء والموجات"]},"prereq_ids":["found.reading-arabic"],"in_chapter":true,"misconceptions":[]},{"id":"pt.atomic-radius-trend","kind":"concept","title":"Atomic radius trend","titles":{"en":"Atomic radius trend"},"summary":"Across a period the radius decreases because the growing nuclear charge pulls electrons closer; down a group it increases with added energy levels; repulsion between electrons pushes outward.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"لما نمشي في الـ period، الـ radius بيقل، عشان الـ nuclear charge بتكبر وبتشد الـ electrons لجوّه أكتر. ولما ننزل في الـ group، الـ radius بيزيد، عشان بيتضاف energy levels جديدة. وفي الناحية التانية، التنافر بين الـ electrons بيزقّهم لبرّه.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["تدرج نصف القطر الذري"]},"prereq_ids":["phys.electric-charges","pt.groups-periods"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"}]},{"id":"pt.blocks","kind":"concept","title":"Blocks of the periodic table","titles":{"en":"Blocks of the periodic table"},"summary":"Elements are grouped into s, p, d and f blocks by the sublevel receiving the last electron; the s and p blocks (except the noble gases) are the representative elements, d the main transition and f the inner transition elements; groups carry Roman numerals with A/B labels, and the 18 columns are numbered 1-18.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"العناصر بتتقسم لـ s و p و d و f blocks حسب الـ sublevel اللي بياخد آخر electron. الـ s والـ p blocks (ما عدا الـ noble gases) فيها الـ representative elements، والـ d فيه الـ main transition elements، والـ f فيه الـ inner transition elements. والـ groups ليها رموز A/B، والأعمدة مترقّمة من 1 لـ 18.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["فئات الجدول الدوري: s و p و d و f"]},"prereq_ids":["atom.electron-configuration-writing"],"in_chapter":true,"misconceptions":[]},{"id":"pt.groups-periods","kind":"concept","title":"Periodic table: periods and groups","titles":{"en":"Periodic table: periods and groups"},"summary":"The modern periodic table arranges elements by atomic number into periods (rows, number of energy levels) and groups (columns; in the main groups, elements of one group have similar properties), with metals on the left, non-metals on the right and noble gases in the last group.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ modern periodic table بيرتب العناصر حسب الـ atomic number في periods (صفوف أفقية، رقم الصف = عدد الـ energy levels) و groups (أعمدة رأسية، وعناصر الـ group الواحد خواصها متشابهة في المجموعات الرئيسية). الـ metals على الشمال، والـ non-metals على اليمين، والـ noble gases في آخر group.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الجدول الدوري: الدورات والمجموعات"]},"prereq_ids":["atom.energy-levels","chem.elements-symbols"],"in_chapter":true,"misconceptions":[]},{"id":"pt.ionization-energy","kind":"concept","title":"Ionization energy","titles":{"en":"Ionization energy"},"summary":"Ionization potential (also called ionization energy): the energy needed to remove the most loosely held electron from a gaseous atom; successive ionization energies increase, with a big jump when an electron must be removed from a stable inner level, which is why representative metals show one oxidation state.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ ionization potential (واسمه كمان ionization energy) هو الطاقة اللي محتاجينها عشان نشيل أضعف electron مربوط في ذرة وهي في الحالة الغازية. الـ successive ionization energies بتزيد واحدة ورا التانية، وبتظهر قفزة كبيرة لما الـ electron يضطر يطلع من مستوى داخلي مستقر؛ وده اللي بيخلّي الـ representative metals بيبقى ليها oxidation state واحد.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["جهد التأين"]},"prereq_ids":["chem.ions","pt.atomic-radius-trend"],"in_chapter":true,"misconceptions":[]},{"id":"pt.oxidation-number","kind":"skill","title":"Oxidation state in compounds","titles":{"en":"Oxidation state in compounds"},"summary":"Calculating an element's oxidation state in a compound or ion (sum = 0 or the ion's charge; O usually -2, alkali metals +1, Cl in chlorides -1, SO4 group -2) and naming with Roman numerals, e.g. iron(II), iron(III).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"إزاي تحسب الـ oxidation state لعنصر في compound أو في ion: مجموع الـ oxidation states = صفر في الـ compound، أو = الـ charge بتاعة الـ ion. الـ O غالبًا -2، والـ alkali metals +1، والـ Cl في الـ chlorides -1، والـ SO4 group -2. وبعدها التسمية بالأرقام الرومانية، زي iron(II) و iron(III).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["عدد التأكسد وحسابه في المركب"]},"prereq_ids":["chem.ions","chem.valency-formulas","found.integers"],"in_chapter":true,"misconceptions":[]},{"id":"redox.basic","kind":"concept","title":"Oxidation and reduction by oxygen","titles":{"en":"Oxidation and reduction by oxygen"},"summary":"Oxidation = gain of oxygen (or loss of hydrogen); reduction = loss of oxygen (or gain of hydrogen); the reducing agent takes oxygen away (e.g. CO, H2, C) and the oxidizing agent supplies it.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ oxidation يعني المادة تكسب oxygen (أو تخسر hydrogen)، والـ reduction يعني المادة تخسر oxygen (أو تكسب hydrogen). الـ reducing agent هو اللي بياخد الـ oxygen من المادة التانية (زي CO و H2 و C)، والـ oxidizing agent هو اللي بيدّيها الـ oxygen.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الأكسدة والاختزال (بالأكسجين)"]},"prereq_ids":["chem.equation-balancing","chem.oxides"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":84,"page_to":84,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"redox.electronic","kind":"concept","title":"Oxidation and reduction by electrons","titles":{"en":"Oxidation and reduction by electrons"},"summary":"Oxidation = loss of electrons / increase in oxidation state; reduction = gain of electrons / decrease; the oxidizing agent is reduced and the reducing agent is oxidized.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ oxidation يعني خسارة electrons، فالـ oxidation state بيزيد؛ والـ reduction يعني كسب electrons، فالـ oxidation state بيقل. وخلّي بالك من اللفّة دي: الـ oxidizing agent هو نفسه اللي بيحصله reduction، والـ reducing agent هو نفسه اللي بيحصله oxidation.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الأكسدة والاختزال بالإلكترونات"]},"prereq_ids":["pt.oxidation-number","redox.basic"],"in_chapter":true,"misconceptions":[{"id":"redox.electronic.mc1","label":"Oxidation always needs oxygen.","explanation":"Not necessarily. Oxidation is loss of electrons, so the oxidation state increases. In $\\ce{Zn + CuSO4 -> ZnSO4 + Cu}$ zinc gains no oxygen, yet it loses electrons, so it is oxidized. Gaining oxygen is just one case of oxidation.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ oxidation معناه خسارة electrons، والـ oxygen مش شرط. في تفاعل الـ Zn مع الـ $\\ce{CuSO4}$ الـ Zn ماخدش أي oxygen، ومع كده خسر electrons، يبقى حصله oxidation. كسب الـ oxygen ده مجرد حالة واحدة من حالات الـ oxidation.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":83,"page_to":84,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"relation":"based_on"}]},{"id":"sci.matter-particles","kind":"concept","title":"Matter is made of atoms and molecules","titles":{"en":"Matter is made of atoms and molecules"},"summary":"All matter is made of tiny particles (atoms, molecules) that are always moving and have spaces between them.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ matter كلها معمولة من particles صغيرة جدًا (atoms و molecules)، والـ particles دي دايمًا بتتحرك وبينها مسافات.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["المادة بتتكون من ذرات وجزيئات"]},"prereq_ids":["found.reading-arabic"],"in_chapter":true,"misconceptions":[]},{"id":"stoich.mass-percentage","kind":"skill","title":"Mass percentage of an element","titles":{"en":"Mass percentage of an element"},"summary":"Percentage of an element = (mass of the element in one mole of the compound / molar mass of the compound) x 100.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"النسبة المئوية لأي عنصر = (كتلة العنصر ده في one mole من الـ compound ÷ الـ molar mass بتاعة الـ compound) x 100.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["نسبة العنصر المئوية في المركب"]},"prereq_ids":["found.percentages","stoich.molar-mass"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"stoich.molar-mass","kind":"skill","title":"Molar mass","titles":{"en":"Molar mass"},"summary":"The molar mass of a substance is the sum of the atomic masses in its formula, in grams per mole.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ molar mass بتاعة أي مادة هي مجموع الـ atomic masses اللي في الـ formula بتاعتها، ووحدتها grams per mole.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الكتلة المولية"]},"prereq_ids":["atom.atomic-mass-number","chem.valency-formulas"],"in_chapter":true,"misconceptions":[],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"te.atomic-mass-trend","kind":"concept","title":"Atomic mass: why nickel is abnormal","titles":{"en":"Atomic mass: why nickel is abnormal"},"summary":"Atomic mass increases with atomic number across the series, except nickel (58.7 u) which is lighter than cobalt (58.9 u) because nickel has five stable isotopes whose average mass is 58.7.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ atomic mass بتزيد مع زيادة الـ atomic number على طول الـ series، ما عدا الـ nickel (58.7 u) اللي أخف من الـ cobalt (58.9 u)، عشان الـ nickel ليه خمس stable isotopes متوسط كتلتهم 58.7. المطلوب: تقرا جدول الخواص وتقول السبب. والجدول للتوضيح بس.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الكتلة الذرية وشذوذ النيكل"]},"prereq_ids":["atom.isotopes","te.first-series-elements"],"in_chapter":true,"misconceptions":[{"id":"te.atomic-mass-trend.mc1","label":"Nickel's mass in the table is a misprint.","explanation":"It is not a misprint. Nickel has five stable isotopes, and 58.7 u is their average mass, so nickel comes out lighter than cobalt (58.9 u) even though its atomic number is larger.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، دي مش غلطة مطبعية. الـ nickel ليه خمس stable isotopes، والـ 58.7 ده متوسط كتلهم الحقيقي، وعشان كده طالع أقل من الـ 58.9 بتاعة الـ cobalt.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.atomic-mass-trend.mc2","label":"Atomic mass always follows atomic number.","explanation":"Not in every case. The atomic number counts protons, but the atomic mass is an average over the isotopes, so the two need not rise together: nickel (Z = 28, 58.7 u) is lighter than cobalt (Z = 27, 58.9 u).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش شرط. الـ atomic number بيعدّ الـ protons، إنما الـ atomic mass متوسط على الـ isotopes، فالاتنين مش لازم يزيدوا مع بعض: الـ nickel (Z = 28) أخف من الـ cobalt (Z = 27).","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.mass","section_title":"The atomic mass","section_path":["Transition Elements","The general properties of the first transition elements","The atomic mass"],"relation":"based_on"}]},{"id":"te.atomic-radius","kind":"concept","title":"Atomic radius: nearly constant","titles":{"en":"Atomic radius: nearly constant"},"summary":"Atomic radius changes little across the series and is nearly constant from Cr to Cu, because two opposite factors balance: rising effective nuclear charge pulls electrons in (smaller radius), while the growing number of 3d electrons increases electron-electron repulsion (larger radius). The near-constant size is why these metals form alloys easily.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ atomic radius بيتغيّر تغيير بسيط على طول السلسلة، ومن الـ Cr لحد الـ Cu بيكون ثابت تقريبًا. السبب إن فيه عاملين عكس بعض بيوازنوا بعض: الـ effective nuclear charge بتزيد فبتشد الـ electrons لجوّه (الـ radius يصغر)، وفي نفس الوقت عدد الـ 3d electrons بيزيد فالتنافر بينهم بيزيد (الـ radius يكبر). والحجم اللي يكاد يكون ثابت ده هو السبب إن الـ metals دي بتعمل alloys بسهولة. المطلوب: تشرح بالعاملين مع بعض وتعرف تقرا عمود الـ atomic radius.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["ليه نصف القطر تقريبًا ثابت؟"]},"prereq_ids":["pt.atomic-radius-trend","te.electron-configuration"],"in_chapter":true,"misconceptions":[{"id":"te.atomic-radius.mc1","label":"The radius falls sharply across the series as in s/p periods.","explanation":"No. Across the first transition series the radius changes little, and from Cr to Cu it is nearly constant (book table: 1.15 to 1.17). The rising effective nuclear charge pulls the electrons in, while the growing repulsion between 3d electrons pushes them out, so the two factors nearly balance.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ radius هنا بيتغيّر تغيير بسيط، ومن الـ Cr للـ Cu ثابت تقريبًا، مش زي الـ s/p periods اللي الذرات فيها بتصغر بوضوح. السبب إن التنافر بين الـ 3d electrons اللي بيزيد بيعاكس الـ effective nuclear charge اللي بتزيد.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.atomic-radius.mc2","label":"Only nuclear charge matters.","explanation":"Repulsion between 3d electrons is the second factor.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الـ nuclear charge مش هي العامل الوحيد: فيه عامل تاني، وهو التنافر بين الـ 3d electrons، وده بيكبّر الـ radius وبيعاكس الشدّ.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"}]},{"id":"te.catalysis-examples","kind":"concept","title":"Nickel, iron and V₂O₅ as catalysts","titles":{"en":"Nickel, iron and V₂O₅ as catalysts"},"summary":"Finely divided Ni: hydrogenation (of oils). Fe: Haber-Bosch ammonia, N2 + 3H2 -> 2NH3 (500 °C, 200 atm). V2O5: contact method for sulphuric acid, 2SO2 + O2 -> 2SO3 (450 °C), then SO3 + H2O -> H2SO4. MnO2: decomposition 2H2O2 -> 2H2O + O2.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ finely divided Ni: للـ hydrogenation (of oils). الـ Fe: للـ Haber-Bosch ammonia، N2 + 3H2 -> 2NH3 (500 °C، 200 atm). الـ V2O5: للـ contact method بتاع الـ sulphuric acid، 2SO2 + O2 -> 2SO3 (450 °C)، وبعدين SO3 + H2O -> H2SO4. الـ MnO2: لتفكيك 2H2O2 -> 2H2O + O2. المطلوب: إنك توصّل كل catalyst بالعملية بتاعته، وتكتب الـ equations والظروف فوق السهم.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["أمثلة: Fe في هابر-بوش و V₂O₅ في التلامس"]},"prereq_ids":["chem.ammonia-haber","chem.equation-reading","te.catalytic-activity"],"in_chapter":true,"misconceptions":[{"id":"te.catalysis-examples.mc1","label":"Swapping catalyst-process pairs.","explanation":"These pairs are swapped. In the book, iron is the catalyst of the Haber-Bosch method (ammonia), and $\\ce{V2O5}$ is the catalyst of the contact method (sulphuric acid).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، كده إنت بدّلت الأزواج: الـ V2O5 مش بتاع الـ Haber، والـ Fe مش بتاع الـ contact method. الصح: الـ Fe مع الـ Haber-Bosch (ammonia)، والـ V2O5 مع الـ contact method (sulphuric acid).","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.catalysis-examples.mc2","label":"Writing the catalyst as a reactant instead of over the arrow.","explanation":"A catalyst is not used up in the reaction, so it is not a reactant. Write it over the arrow together with the conditions such as temperature and pressure, like Fe over the arrow in the Haber-Bosch equation.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الـ catalyst مابيتستهلكش في التفاعل، فمش reactant. مكانه فوق السهم في المعادلة، مع الظروف زي درجة الحرارة والضغط.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"te.catalytic-activity","kind":"concept","title":"Catalytic activity of transition elements","titles":{"en":"Catalytic activity of transition elements"},"summary":"Transition metals and their compounds are ideal catalysts because their 4s and 3d electrons form bonds between surface atoms and reacting molecules; this raises the reactants' concentration on the surface and weakens their bonds, lowering activation energy and speeding the reaction.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ transition metals والـ compounds بتاعتها catalysts مثالية، عشان الـ 4s والـ 3d electrons بتاعتها بتكوّن bonds بين ذرات السطح والـ reacting molecules. ده بيزوّد الـ concentration بتاع الـ reactants على السطح وبيضعّف الـ bonds اللي فيهم، فالـ activation energy بتقل والـ reaction بيسرع. المطلوب: تقول السبب ده وتقرا الـ energy profile (شكل 1-3: الحدبة أوطى مع الـ catalyst، ونفس الـ net energy released).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["ليه العناصر الانتقالية عوامل حفازة ممتازة؟"]},"prereq_ids":["chem.catalyst","kin.activation-energy","te.electron-configuration"],"in_chapter":true,"misconceptions":[{"id":"te.catalytic-activity.mc1","label":"A catalyst is used up in the reaction.","explanation":"No. A catalyst is not used up: its mass is the same at the end of the reaction. That is why it is written over the arrow, not among the reactants (like Fe in the Haber-Bosch method).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ catalyst مش بيتستهلك في الـ reaction: كتلته في الآخر زي ما هي، وعشان كده بيتكتب فوق السهم مش قبله (زي الـ Fe في طريقة الـ Haber-Bosch).","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.catalytic-activity.mc2","label":"A catalyst increases the amount of product or the energy released.","explanation":"No. A catalyst lowers the activation energy, so the same reaction goes faster. The energy levels of the reactants and the products do not move, so the net energy released stays the same (fig 1-3).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ catalyst بيقلل الـ activation energy لوحدها. مستوى الـ reactants والـ products مابيتحركش، فالـ net energy released بتفضل زي ما هي.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.catalytic-activity.mc3","label":"Activation energy is the energy given out by the reaction.","explanation":"No. Activation energy is the climb from the reactants' level to the top of the hump. The energy the reaction gives out is the net energy released: the drop from the reactants' level to the products' level.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ activation energy هي الطلعة من مستوى الـ reactants لحد قمة الحدبة. إنما الـ energy اللي الـ reaction بيطلّعها هي الـ net energy released: النزلة من الـ reactants للـ products.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":65,"page_to":65,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"te.chromium-oxide-layer","kind":"concept","title":"Why chromium resists the effect of atmosphere","titles":{"en":"Why chromium resists the effect of atmosphere"},"summary":"Chromium is chemically active, yet resists air: the oxide that forms on its surface has a larger volume than the metal atoms it came from, so it forms a continuous non-porous layer that blocks further reaction with oxygen.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ chromium عنصر نشيط كيميائيًا، ومع ذلك بيقاوم الهوا: الـ oxide اللي بيتكوّن على سطحه حجمه أكبر من حجم ذرات الـ metal اللي اتكوّن منها، فبيعمل طبقة متصلة non-porous بتمنع إن الـ oxygen يكمّل تفاعل معاه. المطلوب: إنك تقدر تدّي السبب ده (give reasons)، وتقارنه بطبقة porous (زي الـ rust) بتسيب الـ corrosion يكمّل.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["ليه الكروم مش بيصدى رغم إنه نشيط؟"]},"prereq_ids":["chem.activity-series","chem.rusting-corrosion","te.uses-v-cr"],"in_chapter":true,"misconceptions":[{"id":"te.chromium-oxide-layer.mc1","label":"Chromium resists air because it is an unreactive metal.","explanation":"No. Chromium is a chemically active metal. It resists the air because the oxide formed on its surface has a larger volume than the metal atoms, making a non-porous layer that stops further reaction with oxygen.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ chromium metal نشيط فعلًا؛ اللي بيحميه هو طبقة الـ oxide اللي على سطحه.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.chromium-oxide-layer.mc2","label":"Any oxide layer protects a metal.","explanation":"Not any layer. Chromium's oxide has a larger volume than the metal atoms it came from, so it forms a continuous non-porous layer that stops oxygen from reaching the metal. A porous layer, like rust, lets the reaction continue underneath.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش أي طبقة؛ الطبقة الـ non-porous تحديدًا هي اللي بتحمي.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"}]},{"id":"te.cr-cu-anomaly","kind":"concept","title":"Abnormal electronic configuration of chromium and copper","titles":{"en":"Abnormal electronic configuration of chromium and copper"},"summary":"Cr is [Ar] 4s1 3d5 (not 4s2 3d4) and Cu is [Ar] 4s1 3d10 (not 4s2 3d9): the atom is lower in energy (extra stable) when d is half-filled (d5) or completely filled (d10) - though the book notes this is not the only factor.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ Cr توزيعه [Ar] 4s1 3d5 (مش 4s2 3d4)، والـ Cu توزيعه [Ar] 4s1 3d10 (مش 4s2 3d9): الذرة بتبقى طاقتها أقل (extra stable) لما الـ d يبقى half-filled (d5) أو completely filled (d10)، مع إن الكتاب بينبّه إن ده مش العامل الوحيد. المطلوب: تكتب التوزيعين وتدّي السبب.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["شذوذ توزيع الكروم والنحاس"]},"prereq_ids":["te.electron-configuration"],"in_chapter":true,"misconceptions":[{"id":"te.cr-cu-anomaly.mc1","label":"Cr = [Ar] 4s2 3d4 and Cu = [Ar] 4s2 3d9.","explanation":"That is the expected pattern, but the book writes Cr as [Ar] $4s^1\\,3d^5$ and Cu as [Ar] $4s^1\\,3d^{10}$. The atom has lower energy (extra stability) when 3d is half-filled ($d^5$) or completely filled ($d^{10}$).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، ده توزيع القاعدة العامة، لكن الكتاب بيكتب الـ Cr كـ [Ar] 4s1 3d5 والـ Cu كـ [Ar] 4s1 3d10، عشان الذرة بتبقى طاقتها أقل (extra stable) لما الـ 3d يبقى half-filled (d5) أو completely filled (d10).","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.cr-cu-anomaly.mc2","label":"Other elements also 'promote' an electron (e.g. Fe 4s1 3d7, Ni 3d10); only Cr and Cu do in this series.","explanation":"In this series, Cr and Cu are the two exceptions. Fe stays [Ar] $4s^2\\,3d^6$ and Ni stays [Ar] $4s^2\\,3d^8$ (book table): moving one 4s electron would not make their 3d half-filled ($d^5$) or completely filled ($d^{10}$).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش صح: في السلسلة دي مفيش غير الـ Cr والـ Cu اللي بينقلوا electron من الـ 4s للـ 3d. الـ Fe والـ Ni ماشيين على القاعدة العامة وبيحتفظوا بالـ 4s2، لأن نقل electron عندهم مش هيخلّي الـ 3d لا half-filled (d5) ولا completely filled (d10).","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"}]},{"id":"te.d-block-groups","kind":"concept","title":"Main transition elements (d-block)","titles":{"en":"Main transition elements (d-block)"},"summary":"In the d-block the (n-1)d sublevel is filled in sequence from column to column (with exceptions such as Cr and Cu), and since d holds up to 10 electrons the block has 10 vertical columns, from ns2 (n-1)d1 to ns2 (n-1)d10. Left to right: IIIB(3), IVB(4), VB(5), VIB(6), VIIB(7), then VIII made of three columns (8, 9, 10) whose elements resemble their horizontal neighbours more than the elements below them, then IB(11) and IIB(12); IIB is, from one point of view, not counted as transition.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"في الـ d-block الـ (n-1)d sublevel بيتملي بالترتيب من column للي بعده (مع استثناءات زي الـ Cr والـ Cu)، ولأن الـ d بيشيل لحد 10 electrons فالـ block ده فيه 10 columns رأسية، من ns2 (n-1)d1 لحد ns2 (n-1)d10. من الشمال لليمين: IIIB(3)، IVB(4)، VB(5)، VIB(6)، VIIB(7)، وبعدين VIII، وده متكوّن من تلات columns (8، 9، 10) وعناصره شبه جيرانها الأفقيين أكتر من العناصر اللي تحتها، وبعدين IB(11) و IIB(12). والـ IIB من وجهة نظر معيّنة مش بيتحسب من الـ transition elements. المطلوب: تربط أسماء الـ groups (الرقم الروماني + B، والأرقام من 3 لـ 12) بالـ columns وبعدد الـ d electrons.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["مجموعات الفئة d (من IIIB لـ IIB)"]},"prereq_ids":["atom.sublevels","te.position-in-periodic-table"],"in_chapter":true,"misconceptions":[{"id":"te.d-block-groups.mc1","label":"Group VIII is one column.","explanation":"No. Group VIII is three vertical columns, 8, 9 and 10, not one. That is why the d-block has ten columns even though it carries eight group labels.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ group VIII مش column واحد، ده تلات columns: 8 و9 و10.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.d-block-groups.mc2","label":"The d-block has 8 columns because there are 8 B-groups.","explanation":"No. The d sublevel holds up to ten electrons and is filled in sequence across the block, so the d-block has ten columns. There are fewer group labels because group VIII covers three columns (8, 9, 10).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الـ d-block فيه 10 columns مش 8، عشان الـ d sublevel بيشيل 10 electrons.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.d-block-groups.mc3","label":"Group VIII elements resemble the elements below them most.","explanation":"No. The elements of group VIII resemble their horizontal neighbours in the same period (for example Fe, Co and Ni) more than the elements below them in the same column.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"بالعكس، عناصر الـ group VIII شبه جيرانها الأفقيين أكتر من العناصر اللي تحتها.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"te.definition","kind":"concept","title":"Definition of the transition element","titles":{"en":"Definition of the transition element"},"summary":"A transition element is one whose d or f orbitals hold electrons but are incomplete, either in the atom or in one of its oxidation states.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ transition element هو العنصر اللي الـ d أو الـ f orbitals بتوعه فيها electrons لكن مش مكتملة، سواء في الذرة نفسها أو في حالة من الـ oxidation states بتاعته. المطلوب: تقول التعريف ده وتطبّق الاختبارين (الذرة الأول، وبعدين الـ ions بتاعتها). وبالتعريف ده الـ Sc يبقى transition element (ذرته 3d1).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["تعريف العنصر الانتقالي"]},"prereq_ids":["te.oxidation-states-trend"],"in_chapter":true,"misconceptions":[{"id":"te.definition.mc1","label":"Every d-block element is a transition element.","explanation":"No. Being in the d-block is not the test. Zinc is in the d-block, but its d sublevel is complete ($d^{10}$) both in the atom and in the $\\ce{Zn^{2+}}$ ion, so it is not a transition element.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، المكان في الـ d-block مش هو الاختبار. الـ Zn مثلًا في الـ d-block، لكن الـ d بتاعه مكتمل (d10) في الذرة وفي الـ ion، فمش transition element.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.definition.mc2","label":"Sc is not transition because Sc3+ is d0.","explanation":"By the book it is: atom 3d1.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، حسب الكتاب الـ Sc يعتبر transition element: ذرته 3d1، يعني الـ d فيها electrons ومش مكتملة في الذرة، وده كفاية حتى لو الـ Sc3+ يبقى d0.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.definition.mc3","label":"Only the neutral atom is checked.","explanation":"The definition checks two places: the atom, or one of its oxidation states. The Cu atom is $3d^{10}$, but $\\ce{Cu^{2+}}$ is $3d^9$, which is incomplete, so copper is a transition element.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"التعريف بيبص على مكانين: الذرة، أو حالة من الـ oxidation states بتاعتها. الـ Cu مثلًا ذرته 3d10، لكن الـ Cu2+ بيبقى 3d9 ومش مكتمل، فالـ Cu يبقى transition element.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.definition","section_title":"The transition element (definition)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","The transition element (definition)"],"relation":"based_on"}]},{"id":"te.definition-applied","kind":"concept","title":"Are coinage metals and zinc transition elements?","titles":{"en":"Are coinage metals and zinc transition elements?"},"summary":"Coinage metals Cu, Ag, Au are d10 in the atom, but in their +2/+3 states d is incomplete (d9/d8), so they are transition elements. Zn, Cd, Hg are d10 in the atom and in their +2 ion, so they are not.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ coinage metals (Cu, Ag, Au) بيبقى الـ d فيها d10 في الذرة، لكن في الـ +2/+3 states الـ d بيبقى incomplete (d9/d8)، فهي transition elements. أما الـ Zn والـ Cd والـ Hg فهي d10 في الذرة وفي الـ +2 ion بتاعها، فمش transition elements. المطلوب: تحكم على أي عنصر أو ion وتبرّر حكمك بالـ configurations.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["النحاس انتقالي.. والزنك لأ!"]},"prereq_ids":["te.definition"],"in_chapter":true,"misconceptions":[{"id":"te.definition-applied.mc1","label":"Cu is not transition because its atom is d10.","explanation":"The Cu atom is $d^{10}$, but in the +2 state its d sublevel becomes $d^9$, which is incomplete. The definition asks for an incomplete d sublevel in the atom or in one of its oxidation states, so copper is a transition element.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، صح إن ذرة الـ Cu هي d10، لكن في الـ +2 state الـ d بيبقى d9 يعني incomplete. والتعريف بيكفيه إن الـ d يبقى incomplete في الذرة أو في واحدة من الـ oxidation states، فالـ Cu يبقى transition element.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.definition-applied.mc2","label":"Zn is transition because it sits in the d-block.","explanation":"Position in the d-block is not the book's test. Zinc is $d^{10}$ in the atom and in the +2 ion, so its d sublevel is complete in both, and it is not a transition element although it sits in the d-block.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مكان العنصر في الـ d-block مش هو اختبار الكتاب. الـ Zn هو d10 في الذرة وفي الـ +2 ion، يعني الـ d مكتمل في الحالتين، وعشان كده مش transition element رغم إنه في الـ d-block.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.definition-applied.mc3","label":"Groups IB and IIB are both excluded.","explanation":"Group IB (Cu, Ag, Au) is in: its d sublevel becomes $d^9$ or $d^8$ in the +2 or +3 state. Group IIB (Zn, Cd, Hg) is out, because it is $d^{10}$ in the atom and in the +2 ion.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ group IB (Cu, Ag, Au) جوه: الـ d بيبقى d9 أو d8 في الـ +2 أو +3 state. اللي برّه هو الـ group IIB (Zn, Cd, Hg)، لأنه d10 في الذرة وفي الـ +2 ion.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.ex1","section_title":"Coinage metals","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Coinage metals"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":11,"page_to":11,"section_key":"ch1.config.ex2","section_title":"Zinc, cadmium and mercury","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Zinc, cadmium and mercury"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"}]},{"id":"te.density-trend","kind":"concept","title":"Density increases with atomic number","titles":{"en":"Density increases with atomic number"},"summary":"Most have high density, and density increases with atomic number because atomic mass increases while atomic size stays nearly constant (more mass in about the same volume).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"أغلب العناصر دي الـ density بتاعتها عالية، والـ density بتزيد مع زيادة الـ atomic number، عشان الـ atomic mass بيزيد والـ atomic size بيفضل تقريبًا ثابت (يعني mass أكتر في نفس الحجم تقريبًا). المطلوب: تشرح ده وتعرف تقرا عمود الـ density.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["ليه كثافتها عالية وبتزيد؟"]},"prereq_ids":["phys.density","te.atomic-mass-trend","te.atomic-radius"],"in_chapter":true,"misconceptions":[{"id":"te.density-trend.mc1","label":"Density rises because the atoms get much smaller.","explanation":"Size is nearly constant; mass rises.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، حجم الذرات (الـ atomic size) تقريبًا ثابت؛ اللي بيزيد هو الـ atomic mass.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.table","section_title":"Data table (atomic mass, radius, density, melting and boiling points)","section_path":["Transition Elements","The general properties of the first transition elements","Data table (atomic mass, radius, density, melting and boiling points)"],"relation":"based_on"}]},{"id":"te.electron-configuration","kind":"skill","title":"Electronic configuration of the first transition series","titles":{"en":"Electronic configuration of the first transition series"},"summary":"After Ca ([Ar] 4s2) the five 3d orbitals receive one electron each up to Mn (3d5), then electrons pair up to Zn (3d10), following Hund's rule. The usual form is [Ar] 4s2 3d(Z-20), with two exceptions: Cr [Ar] 4s1 3d5 and Cu [Ar] 4s1 3d10.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"بعد الـ Ca ([Ar] 4s2)، الـ 3d orbitals الخمسة بياخدوا electron واحد في كل orbital لحد الـ Mn (3d5)، وبعدين الـ electrons تبدأ تعمل أزواج لحد الـ Zn (3d10)، وده حسب الـ Hund's rule. الشكل المعتاد هو [Ar] 4s2 3d(Z-20)، وفيه استثناءين: الـ Cr [Ar] 4s1 3d5 والـ Cu [Ar] 4s1 3d10. المطلوب: إنك تكتب الـ configuration كامل ومختصر بالـ [Ar] للعناصر من Z = 21 لـ 30، وترسم مربعات الـ 3d. وجدول الـ configurations اللي في الكتاب للتوضيح مش للحفظ.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["التوزيع الإلكتروني للسلسلة الانتقالية الأولى"]},"prereq_ids":["atom.electron-configuration-writing","atom.hund-rule","atom.orbitals","te.first-series-elements"],"in_chapter":true,"misconceptions":[{"id":"te.electron-configuration.mc1","label":"Pairing electrons in the first 3d orbital before the others are singly filled.","explanation":"This breaks Hund's rule. The five 3d orbitals each take one electron before pairing starts, so $3d^3$ is three unpaired electrons in three separate boxes, not a pair plus one.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، كده إنت بتتجاهل الـ Hund's rule: الـ 5 orbitals بتوع الـ 3d بياخدوا electron واحد في كل orbital الأول، وبعد كده تبدأ الأزواج.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.electron-configuration.mc2","label":"Leaving out 4s and writing only [Ar] 3dn.","explanation":"Keep the 4s. It fills at Ca ([Ar] $4s^2$) before 3d and stays in the configuration from Sc to Zn ($4s^2$, or $4s^1$ in Cr and Cu). So the usual form is [Ar] $4s^2\\,3d^{Z-20}$, e.g. Fe = [Ar] $4s^2\\,3d^6$.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ 4s بيتملى عند الـ Ca ([Ar] 4s2) قبل الـ 3d، والـ 4s بيفضل موجود في الـ configuration من الـ Sc لحد الـ Zn (4s2، أو 4s1 في الـ Cr والـ Cu). عشان كده الشكل المعتاد [Ar] 4s2 3d(Z-20)، ماتشيلش الـ 4s من الـ configuration.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"te.fe2-fe3-mn2-stability","kind":"concept","title":"Iron(II) is easily oxidized while manganese(II) is not","titles":{"en":"Iron(II) is easily oxidized while manganese(II) is not"},"summary":"Fe2+ is 3d6; losing one more electron gives Fe3+ 3d5, a half-filled, more stable sublevel, so oxidation is easy. Mn2+ is already 3d5; oxidation to Mn3+ (3d4) would break the stable half-filled sublevel, so Mn2+ is not readily oxidized. Iron's important states are +2 (loss of 4s2) and +3 (stable 3d5); iron never reaches +8 and its states above +3 are unimportant.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ Fe2+ تركيبه 3d6؛ ولو خسر electron كمان بيبقى Fe3+ تركيبه 3d5، يعني sublevel نصه مليان وأكتر استقرارًا، وعشان كده الـ oxidation بتاعه سهل. أما الـ Mn2+ فهو أصلًا 3d5؛ ولو اتأكسد لـ Mn3+ (3d4) هيكسر الـ half-filled sublevel المستقر ده، فالـ Mn2+ مش بيتأكسد بسهولة. أهم oxidation states للـ iron هي +2 (لما يخسر الـ 4s2) و+3 (الـ 3d5 المستقر)؛ والـ iron مش بيوصل لـ +8، والـ states اللي فوق +3 مش مهمة. المطلوب: تشرح ده بالـ orbital-box diagrams.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["ليه Fe²⁺ بيتأكسد بسهولة و Mn²⁺ لأ؟"]},"prereq_ids":["redox.electronic","te.cr-cu-anomaly","te.ion-configuration"],"in_chapter":true,"misconceptions":[{"id":"te.fe2-fe3-mn2-stability.mc1","label":"Reversing the cases.","explanation":"It is the other way round. $\\ce{Fe^{2+}}$ ($3d^6$) is easily oxidized because losing one more electron gives $\\ce{Fe^{3+}}$ ($3d^5$), a half-filled, more stable sublevel. $\\ce{Mn^{2+}}$ is already $3d^5$, so it is not readily oxidized.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، إنت عكست الحالتين: الـ Fe2+ (3d6) هو اللي بيتأكسد بسهولة عشان يوصل لـ 3d5، إنما الـ Mn2+ أصلًا 3d5 فمش بيتأكسد بسهولة.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.fe2-fe3-mn2-stability.mc2","label":"Fe3+ is more stable just because it has a bigger charge.","explanation":"The reason is the half-filled 3d5.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش الـ charge الأكبر هو السبب. الـ Fe3+ أكتر استقرارًا عشان الـ 3d sublevel بتاعه 3d5، يعني نصه مليان.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.fe2-fe3-mn2-stability.mc3","label":"Iron's maximum oxidation state is +8.","explanation":"No. Counting all its 4s and 3d electrons gives 8, but iron does not reach +8. Its important states are +2 and +3; the states above +3 are not important (the book table goes up to +6, in $\\ce{Na2FeO4}$).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الفكرة دي جاية من إنك بتعدّ كل الـ 4s + 3d electrons بتوعه (8). لكن الـ iron مش بيوصل لـ +8؛ أهم states عنده +2 و+3، واللي فوق +3 مش مهم.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"te.first-series-elements","kind":"concept","title":"Elements of the first transition series","titles":{"en":"Elements of the first transition series"},"summary":"The ten elements Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn (Z = 21-30) in order with their symbols. Together they are a small share of the earth's crust by mass (book: nearly 7%; the abundance table shows Fe about 5%, Sc and Co among the rarest), yet they have great economic importance.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"العناصر العشرة Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn (Z = 21-30) بالترتيب ومعاها رموزها. مع بعض نسبتهم صغيرة من كتلة القشرة الأرضية (الكتاب بيقول تقريبًا 7%، وجدول الوفرة بيوضح إن الـ Fe حوالي 5%، والـ Sc والـ Co من أندر العناصر)، ومع ذلك ليهم أهمية اقتصادية عالية. المطلوب: إنك ترتّبهم بالـ Z بتاعهم وتعرف تقرا جدول الوفرة.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["عناصر السلسلة الانتقالية الأولى (من Sc لـ Zn)"]},"prereq_ids":["found.tables-graphs","te.transition-series"],"in_chapter":true,"misconceptions":[{"id":"te.first-series-elements.mc1","label":"Being abundant in the crust is what makes a metal economically important.","explanation":"Abundance is not what makes them important. Together these ten elements form nearly 7% of the earth's crust by mass, and most of them are rare (e.g. Sc and Co); even iron, the most common, is about 5%. Yet they have high economic importance.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، مش الوفرة هي اللي بتدّيهم أهميتهم. العناصر العشرة دي مع بعض حوالي 7% من كتلة القشرة الأرضية، وأغلبها نادر (زي الـ Sc والـ Co)، وحتى الـ Fe، أكترهم وجودًا، حوالي 5%. ومع كده أهميتها الاقتصادية عالية جدًا.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.first-series-elements.mc2","label":"Swapping the order of Co/Ni or Cr/Mn.","explanation":"The order follows the atomic number Z: Cr (24) comes before Mn (25), and Co (27) before Ni (28). So the series runs Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الترتيب ماشي على الـ Z: الـ Cr (24) قبل الـ Mn (25)، والـ Co (27) قبل الـ Ni (28). عشان كده مينفعش تبدّل مكانهم.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.abundance","section_title":"Percent of each element in the earth's crust","section_path":["Transition Elements","The First Transition Series","Percent of each element in the earth's crust"],"relation":"based_on"}]},{"id":"te.high-melting-points","kind":"concept","title":"High melting and boiling points","titles":{"en":"High melting and boiling points"},"summary":"Transition metals have high melting and boiling points because both 4s and 3d electrons share in the metallic bond, making it strong.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ transition metals عندها melting and boiling points عالية، عشان الـ 4s والـ 3d electrons الاتنين بيشاركوا في الـ metallic bond، فبيبقى bond قوي. المطلوب: إنك تقول السبب ده، وتقارن بالـ s-block metals اللي الـ s electrons لوحدها هي اللي بتشارك فيها.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["ليه درجات انصهارها وغليانها عالية؟"]},"prereq_ids":["bond.metallic-bond","phys.states-melting-boiling","te.electron-configuration","te.metallic-properties"],"in_chapter":true,"misconceptions":[{"id":"te.high-melting-points.mc1","label":"High melting points are due to heavy atoms.","explanation":"Heavy atoms are not the reason. Copper (63.5) is heavier than chromium (52), yet it melts much lower (1083 °C against 1890 °C in the book table). What matters is the strength of the metallic bond, in which both 4s and 3d electrons share.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، مش تقل الذرات هو السبب: الـ Cu أتقل من الـ Cr وبرضه بينصهر عند درجة أقل بكتير. اللي بيحدد هو قوة الـ metallic bond، اللي بيشارك فيها الـ 4s والـ 3d electrons الاتنين.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.high-melting-points.mc2","label":"Only the 4s electrons form the metallic bond.","explanation":"That fits s-block metals such as calcium. In the transition metals both the 4s and the 3d electrons share in the metallic bond, which makes it strong and gives high melting and boiling points.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"ده حال الـ s-block metals زي الـ Ca. في الـ transition metals الـ 4s والـ 3d electrons الاتنين بيشاركوا في الـ metallic bond، وعشان كده بيبقى أقوى والـ melting point أعلى.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.table","section_title":"Data table (atomic mass, radius, density, melting and boiling points)","section_path":["Transition Elements","The general properties of the first transition elements","Data table (atomic mass, radius, density, melting and boiling points)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"}]},{"id":"te.ion-configuration","kind":"skill","title":"Ions: 4s electrons are lost first","titles":{"en":"Ions: 4s electrons are lost first"},"summary":"When a first-series atom is oxidized it loses its 4s electrons first, then 3d electrons one by one for higher states. All members except Sc show +2 (book: after losing the 4s electrons; for Cr and Cu, which have 4s1, the second electron comes from 3d). Examples: Fe2+ [Ar]3d6, Fe3+ [Ar]3d5, Cr2+ [Ar]3d4, Cu2+ [Ar]3d9, Zn2+ [Ar]3d10.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"لما ذرة من الـ first-series تتأكسد، بتفقد الـ 4s electrons الأول، وبعدين الـ 3d electrons واحد ورا التاني عشان توصل لـ states أعلى. كل العناصر ما عدا الـ Sc بتدّي +2 (الكتاب بيقول: بعد ما تفقد الـ 4s electrons؛ وفي الـ Cr والـ Cu، اللي عندهم 4s1، الـ electron التاني بييجي من الـ 3d). أمثلة: Fe2+ [Ar]3d6، Fe3+ [Ar]3d5، Cr2+ [Ar]3d4، Cu2+ [Ar]3d9، Zn2+ [Ar]3d10. المطلوب: تكتب configuration أي ion، وتعرف العنصر من configuration الـ ion بتاعه.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["توزيع الأيونات: الـ 4s بتطلع الأول"]},"prereq_ids":["chem.ions","te.electron-configuration"],"in_chapter":true,"misconceptions":[{"id":"te.ion-configuration.mc1","label":"The last electron added leaves first, so Fe2+ = [Ar] 4s2 3d4.","explanation":"4s leaves first: Fe2+ = [Ar] 3d6.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ 4s هو اللي بيطلع الأول، مش آخر electron دخل: Fe2+ = [Ar] 3d6.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.ion-configuration.mc2","label":"Cr2+/Cu2+ keep the 4s1 anomaly.","explanation":"Ions are built by removing 4s first.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش صح، الـ ions بتتبني بإننا نشيل الـ 4s الأول، فالـ 4s1 بيروح هو كمان.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.ion-configuration.mc3","label":"Every element of the series has a +2 state.","explanation":"Not every element: scandium shows +3 in the book table, not +2. The other members show +2 after losing their 4s electrons (for Cr and Cu, which have $4s^1$, the second electron comes from 3d).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ Sc مالوش غير +3.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.vanadium-ie","section_title":"Successive ionization energies of vanadium","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Successive ionization energies of vanadium"],"relation":"based_on"}]},{"id":"te.magnetic-moment-from-config","kind":"skill","title":"Unpaired electrons and magnetic moment","titles":{"en":"Unpaired electrons and magnetic moment"},"summary":"Procedure: find the metal's oxidation state in the compound, write the ion's 3d configuration (4s lost first), fill 3d boxes by Hund's rule, count unpaired electrons, then classify (0 = diamagnetic) and rank magnetic moments. E.g. TiO2 (Ti4+ d0) < Cr2O3 (Cr3+ d3) < FeCl3 (Fe3+ d5); Zn d10 diamagnetic, Ni2+ d8 (2), Fe2+ d6 (4); ZnSO4 diamagnetic; CoCl2, FeCl2, Fe2(SO4)3 paramagnetic. No formula is used, only counting.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الطريقة: هات الـ oxidation state بتاع الـ metal في الـ compound، واكتب الـ 3d configuration بتاعة الـ ion (الـ 4s بيفقد electrons الأول)، واملا مربعات الـ 3d حسب الـ Hund's rule، وعدّ الـ unpaired electrons، وبعدين صنّف (0 يعني diamagnetic) ورتّب الـ magnetic moments. مثلًا: TiO2 (Ti4+ d0) < Cr2O3 (Cr3+ d3) < FeCl3 (Fe3+ d5)؛ والـ Zn d10 diamagnetic، والـ Ni2+ d8 (2)، والـ Fe2+ d6 (4)؛ والـ ZnSO4 diamagnetic، أما الـ CoCl2 والـ FeCl2 والـ Fe2(SO4)3 فهم paramagnetic. مفيش قانون هنا، الموضوع كله عدّ.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["عدّ الإلكترونات المفردة وترتيب العزم المغناطيسي"]},"prereq_ids":["pt.oxidation-number","te.ion-configuration","te.magnetic-properties"],"in_chapter":true,"misconceptions":[{"id":"te.magnetic-moment-from-config.mc1","label":"Counting unpaired electrons of the neutral atom instead of the ion in the compound.","explanation":"Count the unpaired electrons of the ion in the compound, not of the neutral atom. Find the oxidation state, remove the 4s electrons first, then count the unpaired 3d electrons: in $\\ce{FeCl3}$, $\\ce{Fe^{3+}}$ is $3d^5$ with 5 unpaired electrons.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، اللي بيتعدّ هو الـ unpaired electrons بتوع الـ ion اللي في الـ compound، مش الذرة المتعادلة: هات الـ oxidation state الأول، وشيل الـ electrons من الـ 4s الأول، وبعدين عدّ اللي فاضل unpaired في الـ 3d.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.magnetic-moment-from-config.mc2","label":"Pairing early.","explanation":"$d^6$ is not three pairs. By Hund's rule the five 3d orbitals each take one electron before pairing starts, so $d^6$ is one pair plus four unpaired electrons: 4 unpaired, as for $\\ce{Fe^{2+}}$ in the book.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ d6 مش 3 أزواج و0 unpaired: حسب الـ Hund's rule الـ 5 orbitals بتوع الـ 3d بياخدوا electron واحد الأول قبل أي أزواج، فالـ d6 = زوج واحد + 4 فرادى، يعني 4 unpaired electrons.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.magnetic-moment-from-config.mc3","label":"Every compound of a transition metal is paramagnetic.","explanation":"Not every compound. A compound is paramagnetic when its metal ion has unpaired electrons. Compounds of $\\ce{Zn^{2+}}$ ($d^{10}$), $\\ce{Ti^{4+}}$ and $\\ce{Sc^{3+}}$ ($d^0$) have none, so they are diamagnetic; the book says most transition-element compounds are paramagnetic.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش شرط؛ الـ compound بيبقى paramagnetic لو الـ ion بتاعه فيه unpaired electrons. الـ compounds بتاعة الـ Zn2+ والـ Ti4+ والـ Sc3+ مش paramagnetic (الـ ion فيها d10 أو d0).","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic.ex-b","section_title":"Order of magnetic moments","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties","Order of magnetic moments"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q4","section_title":"Classify to diamagnetic or paramagnetic","section_path":["Transition Elements","Evaluation","Classify to diamagnetic or paramagnetic"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"}]},{"id":"te.magnetic-properties","kind":"concept","title":"Paramagnetic and diamagnetic substances","titles":{"en":"Paramagnetic and diamagnetic substances"},"summary":"A spinning unpaired electron creates a small magnetic field. Paramagnetic substance: has unpaired electrons, so it is attracted to an external magnetic field; its magnetic moment rises with the number of unpaired electrons (most transition-element compounds are paramagnetic). Diamagnetic substance: all electrons paired with opposite spins, magnetic moment zero, repelled by an external field.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ unpaired electron وهو بيلف حوالين نفسه بيعمل magnetic field صغير. الـ paramagnetic substance فيها unpaired electrons، فبتتجذب للـ external magnetic field، والـ magnetic moment بتاعها بيزيد كل ما عدد الـ unpaired electrons يزيد (ومعظم compounds الـ transition elements كده paramagnetic). أما الـ diamagnetic substance فكل الـ electrons فيها paired بـ opposite spins، والـ magnetic moment بتاعها بصفر، فبتتنافر مع الـ external field. المطلوب: تعرّف الاتنين وتشرح ليه واحدة بتتجذب والتانية بتتنافر.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["بارامغناطيسية ودايامغناطيسية"]},"prereq_ids":["atom.hund-rule","phys.magnetic-field"],"in_chapter":true,"misconceptions":[{"id":"te.magnetic-properties.mc1","label":"Paramagnetic means a permanent magnet.","explanation":"It is only attracted inside an external field.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ paramagnetic substance مش magnet دايم؛ هي مجرد بتتجذب وهي جوه external magnetic field، ولو شلت الـ field مش هتفضل magnet.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.magnetic-properties.mc2","label":"Diamagnetic means not affected by a magnet.","explanation":"It is affected, in the opposite way. A diamagnetic substance has all its electrons paired, so its magnetic moment is zero and it is repelled by an external magnetic field.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ diamagnetic substance بتتأثر بالـ magnet، لكن بشكل عكسي: بتتنافر مع الـ external magnetic field بدل ما تتجذب له.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.magnetic-properties.mc3","label":"More electrons means more magnetic.","explanation":"The total number of electrons is not what counts. Unpaired electrons create the magnetic moment; paired electrons with opposite spins cancel each other. Zinc ($d^{10}$) has many electrons, all paired, so it is diamagnetic.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، العبرة مش بعدد الـ electrons كله؛ الـ unpaired electrons تحديدًا هما اللي بيعملوا الـ magnetic moment، أما الـ paired electrons بالـ opposite spins فمش بيزوّدوه.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic.ex-a","section_title":"Paramagnetic or diamagnetic","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties","Paramagnetic or diamagnetic"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"}]},{"id":"te.metallic-properties","kind":"concept","title":"The metallic property","titles":{"en":"The metallic property"},"summary":"All are solids with metallic luster and good conductivity of heat and electricity. Their chemical activity varies: Cu has limited activity, Fe is moderate (rusts in air), Sc is highly active (displaces hydrogen of water strongly).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"كلها solids ليها metallic luster، وبتوصّل الحرارة والكهربا كويس. لكن الـ chemical activity بتاعتها بتختلف: الـ Cu نشاطه محدود، والـ Fe نشاطه متوسط (بيصدّي في الهوا)، والـ Sc نشاطه عالي (بيحل محل الـ hydrogen بتاع الماية بقوة). المطلوب: توصف الخواص دي وترتّب أمثلة حسب النشاط.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الخواص الفلزية للعناصر الانتقالية"]},"prereq_ids":["chem.activity-series","te.first-series-elements"],"in_chapter":true,"misconceptions":[{"id":"te.metallic-properties.mc1","label":"All transition metals are unreactive like copper.","explanation":"Not all of them. Their chemical activity varies: copper has limited chemical activity, iron is moderate (it rusts when exposed to air), and scandium is highly active (it replaces the hydrogen of water strongly).","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، مش كلهم نشاطهم محدود زي الـ Cu. الـ chemical activity بتختلف من عنصر للتاني: الـ Fe نشاطه متوسط وبيصدّي في الهوا الرطب، والـ Sc نشاطه عالي وبيحل محل الـ hydrogen بتاع الماية بقوة.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.metallic-properties.mc2","label":"All transition metals react strongly with water.","explanation":"Reacting strongly with water describes scandium. Activity varies along the series: copper has limited chemical activity and iron is moderate.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، التفاعل القوي مع الماية ده وصف للـ Sc تحديدًا. الـ chemical activity بتختلف في السلسلة: الـ Cu نشاطه محدود، والـ Fe نشاطه متوسط.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"te.multiple-oxidation-states","kind":"concept","title":"Why several oxidation states","titles":{"en":"Why several oxidation states"},"summary":"Representative metals usually show one oxidation state, but transition metals show several, because their 4s and 3d electrons are close in energy and are removed in sequence, so successive ionization potentials (ionization energies) rise gradually (vanadium: 648, 1346, 2858, 4643, 6523 kJ/mol).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ representative metals غالبًا بيبقى ليها oxidation state واحدة، إنما الـ transition metals بيبقى ليها أكتر من واحدة، عشان الـ electrons بتوع الـ 4s والـ 3d قريبين من بعض في الطاقة وبيتشالوا ورا بعض بالترتيب، فالـ successive ionization potentials (واسمها كمان ionization energies) بتزيد بالتدريج (الـ vanadium: 648، 1346، 2858، 4643، 6523 kJ/mol). المطلوب: تقرا الـ flowchart بتاع الـ ionization للـ vanadium وتشرح ليه أكتر من state ممكن نوصلها.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["ليه العناصر الانتقالية ليها حالات تأكسد كتير؟"]},"prereq_ids":["pt.ionization-energy","te.oxidation-states-trend"],"in_chapter":true,"misconceptions":[{"id":"te.multiple-oxidation-states.mc1","label":"There is a huge jump in ionization energy right after the 4s electrons leave.","explanation":"No. In vanadium the ionization potentials rise gradually from one electron to the next (648, 1346, 2858, 4643, 6523 kJ/mol), with no huge jump after the 4s electrons leave, because the 4s and 3d electrons are close in energy.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، حتى بعد ما الـ 4s electrons يمشوا، الزيادة في الـ ionization energy بتيجي بالتدريج.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.multiple-oxidation-states.mc2","label":"They have many oxidation states simply because they have many electrons.","explanation":"It is not just the number of electrons. The 4s and 3d electrons are close in energy, so they are removed in sequence and the successive ionization potentials rise gradually; that makes several oxidation states reachable.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش مجرد عدد الـ electrons. السبب إن الـ electrons بتوع الـ 4s والـ 3d قريبين من بعض في الطاقة، فبيتشالوا ورا بعض والـ ionization energies بتزيد بالتدريج، وده اللي بيخلّي أكتر من oxidation state ممكنة.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.vanadium-ie","section_title":"Successive ionization energies of vanadium","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Successive ionization energies of vanadium"],"relation":"based_on"}]},{"id":"te.oxidation-states-trend","kind":"concept","title":"Oxidation states from Sc to Zn","titles":{"en":"Oxidation states from Sc to Zn"},"summary":"The maximum oxidation state rises from Sc (+3) to Mn (+7, group VIIB) then falls to Zn (+2, group IIB); the maximum state does not exceed the group number, except in group IB (Cu, Ag, Au: Cu shows +2). In group VIII it stays well below 8 (book table: Fe up to +6, Co and Ni up to +4). Sc does not form Sc4+ because Sc3+ already has the argon configuration.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"أعلى oxidation state بيزيد من الـ Sc (+3) لحد الـ Mn (+7، group VIIB)، وبعدين يقل لحد الـ Zn (+2، group IIB). أعلى oxidation state مابيعديش رقم الـ group، ما عدا group IB (الـ Cu والـ Ag والـ Au: الـ Cu بيدي +2). وفي group VIII بيفضل أقل من 8 بكتير (جدول الكتاب: الـ Fe لحد +6، والـ Co والـ Ni لحد +4). والـ Sc مابيكوّنش Sc4+ عشان الـ Sc3+ واصل خلاص للـ configuration بتاع الـ argon. المطلوب: إنك تقرا الـ oxidation states من الصيغ اللي في جدول الكتاب (زي KMnO4 +7، K2Cr2O7 +6، V2O5 +5، Na2FeO4 +6)، وتتوقع أعلى oxidation state من الـ configuration أو الـ group. الجدول للتوضيح لا أكتر (صف الـ Cu مكتوب فيه '1,s' وده خطأ مطبعي، المقصود +1، +2).","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["حالات التأكسد: بتزيد لحد Mn وبعدين تقل"]},"prereq_ids":["pt.oxidation-number","te.d-block-groups","te.ion-configuration"],"in_chapter":true,"misconceptions":[{"id":"te.oxidation-states-trend.mc1","label":"Maximum oxidation state = number of 4s + 3d electrons for every element.","explanation":"No. The maximum oxidation state matches the number of 4s + 3d electrons from Sc to Mn (Mn reaches +7). After Mn it stops matching: Fe has 8 such electrons, but its highest state in the book is +6.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، ده صح من الـ Sc لحد الـ Mn تحديدًا؛ بعد كده مابيمشيش، والـ Fe مثلًا مابيوصلش لـ +8.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.oxidation-states-trend.mc2","label":"The maximum state always equals the group number.","explanation":"Not always. The maximum oxidation state does not exceed the group number, but it can fall below it: in group VIII, Fe reaches +6 and Co and Ni +4. Group IB is the exception above it: Cu shows +2.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش شرط: في group VIII الـ Fe لحد +6 والـ Co والـ Ni لحد +4، وفي group IB الـ Cu بيدي +2، يعني أعلى من 1.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.oxidation-states-trend.mc3","label":"Scandium can form Sc4+.","explanation":"Scandium does not form $\\ce{Sc^{4+}}$. As $\\ce{Sc^{3+}}$ it has already reached the argon configuration, so +3 is its highest oxidation state.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ Sc مابيكوّنش Sc4+: لما يبقى Sc3+ بيكون واصل خلاص للـ configuration بتاع الـ argon، فأعلى oxidation state ليه هو +3.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"relation":"based_on"}]},{"id":"te.position-in-periodic-table","kind":"concept","title":"Transition elements in the periodic table","titles":{"en":"Transition elements in the periodic table"},"summary":"Transition elements occupy the middle of the long-form periodic table, between the s-block and the p-block; they are more than 60 elements (over half of the known elements). They split into main transition elements (d-block) and inner transition elements (f-block: lanthanides and actinides). The chapter studies the main transition elements only.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ transition elements واقعة في نص الـ long-form periodic table، بين الـ s-block والـ p-block، وعددها أكتر من 60 عنصر (أكتر من نص العناصر المعروفة). بتنقسم لـ main transition elements (الـ d-block) و inner transition elements (الـ f-block: الـ lanthanides والـ actinides)، والفصل ده بيدرس الـ main transition elements تحديدًا. المطلوب: تحدد مكانها في الجدول وتسمّي النوعين.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["العناصر الانتقالية: مكانها في الجدول الدوري"]},"prereq_ids":["pt.blocks"],"in_chapter":true,"misconceptions":[{"id":"te.position-in-periodic-table.mc1","label":"Transition elements are a handful of metals.","explanation":"They are more than half the known elements.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، دي أكتر من 60 عنصر، يعني أكتر من نص العناصر المعروفة.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.position-in-periodic-table.mc2","label":"Lanthanides and actinides are main transition elements studied here.","explanation":"Lanthanides and actinides are inner transition elements of the f-block, not main transition elements. This chapter studies the main transition elements (the d-block) only.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الـ lanthanides والـ actinides دول inner transition elements من الـ f-block، والفصل ده مش بيدرسهم.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te","section_title":"The transition elements","section_path":["Transition Elements","The transition elements"],"relation":"based_on"}]},{"id":"te.transition-series","kind":"concept","title":"The four transition series","titles":{"en":"The four transition series"},"summary":"The d-block forms four horizontal series by which d sublevel is filling: 1st = 3d (period 4, Sc-21 4s2 3d1 to Zn-30 4s2 3d10); 2nd = 4d (period 5, Y-39 to Cd-48); 3rd = 5d (period 6, from La-57 6s2 5d1 to Hg-80 6s2 4f14 5d10); 4th = 6d (period 7).","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ d-block بيتقسم لأربع series أفقية، حسب أنهي d sublevel بيتملي: الأولى = 3d (period 4، من Sc-21 4s2 3d1 لحد Zn-30 4s2 3d10)؛ التانية = 4d (period 5، من Y-39 لحد Cd-48)؛ التالتة = 5d (period 6، من La-57 6s2 5d1 لحد Hg-80 6s2 4f14 5d10)؛ الرابعة = 6d (period 7). المطلوب: تربط رقم الـ series بالـ period وبالـ (n-1)d sublevel، وتسمّي أول وآخر عنصر في أول تلات series.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["السلاسل الانتقالية الأربعة"]},"prereq_ids":["te.d-block-groups"],"in_chapter":true,"misconceptions":[{"id":"te.transition-series.mc1","label":"The first series fills 4d because it is in period 4.","explanation":"Being in period 4 does not mean 4d. The first series fills the 3d sublevel: in each transition series the filling sublevel is (n-1)d, one level below the period number, so period 4 fills 3d.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ first series بتملا الـ 3d مش الـ 4d، رغم إنها في الـ period 4: الـ sublevel اللي بيتملي هو الـ (n-1)d.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.transition-series.mc2","label":"The first transition series is in period 1.","explanation":"It is not in period 1. The first transition series is in period 4, right after calcium, from Sc (21) to Zn (30), where the 3d sublevel is filled.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ first transition series موجودة في الـ period 4، مش الـ period 1.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":5,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"te.uses-cu-zn","kind":"concept","title":"Economic importance of copper and zinc","titles":{"en":"Economic importance of copper and zinc"},"summary":"Cu: the first metal discovered; Cu-Sn alloy is bronze; good electrical conductor (cables, coins); CuSO4 insecticide, fungicide and in water purification; Fehling's solution (a copper compound) detects glucose, blue turning orange. Zn: galvanizing other metals against rust; ZnO in paints, rubber and cosmetics; ZnS in illuminating paints and X-ray screens.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ Cu: أول metal اتكشف؛ والـ alloy بتاع Cu-Sn هو الـ bronze؛ وهو موصّل كويس للكهربا، عشان كده بيدخل في كابلات الكهربا، وبيدخل كمان في العملات. الـ CuSO4 بيتستخدم insecticide و fungicide وفي تنقية المية؛ والـ Fehling's solution (وهو compound فيه copper) بيكشف الـ glucose، ولونه بيتغيّر من الأزرق للبرتقاني. الـ Zn: بيتعمل بيه galvanizing للـ metals التانية عشان يحميها من الصدأ؛ الـ ZnO بيدخل في الدهانات والمطاط ومستحضرات التجميل؛ والـ ZnS في الدهانات المضيئة وشاشات الـ X-ray.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["النحاس والزنك: استخداماتهم"]},"prereq_ids":["chem.rusting-corrosion","phys.em-spectrum","te.first-series-elements"],"in_chapter":true,"misconceptions":[{"id":"te.uses-cu-zn.mc1","label":"Bronze is copper + zinc.","explanation":"Bronze is a copper-tin alloy, not copper and zinc. The book names copper + tin alloys as bronze; copper with zinc gives a different alloy.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ bronze هو copper + tin. الـ copper مع الـ zinc بيدّي alloy تاني خالص.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.uses-cu-zn.mc2","label":"Fehling's solution turns blue with glucose.","explanation":"It turns from blue to orange.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، هو أصلًا لونه أزرق من الأول، والـ glucose هو اللي بيغيّر لونه من الأزرق للبرتقاني.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":8,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"te.uses-fe-co","kind":"concept","title":"Economic importance of iron and cobalt","titles":{"en":"Economic importance of iron and cobalt"},"summary":"Fe: reinforced concrete, electricity pylons, knives, gun and cannon barrels, surgical tools; catalyst in Haber-Bosch ammonia and in the Fischer-Tropsch conversion of water gas (CO + H2) into fuel. Co: like iron it can be magnetized (magnets); modern dry batteries for cars; has 12 radioactive isotopes, of which Co-60 emits highly penetrating gamma rays used for food preservation, checking industrial product quality, detecting cracks and weld joints, and diagnosing and treating tumours.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ Fe بيدخل في الـ reinforced concrete، وأبراج الكهربا، والسكاكين، ومواسير البنادق والمدافع، وأدوات الجراحة؛ وكمان بيشتغل catalyst في تحضير الـ ammonia بطريقة الـ Haber-Bosch، وفي الـ Fischer-Tropsch اللي بيحوّل الـ water gas (CO + H2) لوقود. الـ Co زي الـ iron بيتمغنط (عشان كده بيتعمل منه magnets)، وبيدخل في الـ modern dry batteries بتاعة العربيات، وليه 12 radioactive isotopes، منهم الـ Co-60 اللي بيطلّع gamma rays ليها قدرة اختراق عالية جدًا، وبنستخدمها في حفظ الأكل، وفحص جودة المنتجات الصناعية، واكتشاف الشروخ ووصلات اللحام، وفي تشخيص الأورام وعلاجها.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الحديد والكوبالت: استخداماتهم (وكوبالت 60)"]},"prereq_ids":["chem.catalyst","phys.radioactivity-gamma","te.first-series-elements"],"in_chapter":true,"misconceptions":[{"id":"te.uses-fe-co.mc1","label":"Water gas is water vapour.","explanation":"It is a mixture of CO and H2.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ water gas مش بخار مية؛ ده خليط من الـ CO والـ H2.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.uses-fe-co.mc2","label":"Cobalt-60 is used because it is magnetic.","explanation":"It is used for its gamma rays.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"مش عشان بيتمغنط؛ الـ Co-60 بنستخدمه عشان الـ gamma rays اللي بيطلّعها.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.uses-fe-co.mc3","label":"Food preserved with Co-60 gamma rays becomes radioactive.","explanation":"No. Gamma rays pass through the food and do not leave a radioactive substance in it; the cobalt-60 stays in the source, so the food does not become radioactive.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ gamma rays بتعدّي من الأكل ومش بتسيب فيه مادة radioactive؛ الـ Co-60 نفسه بيفضل في المصدر مش في الأكل، فالأكل مش بيبقى radioactive.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"te.uses-mn","kind":"concept","title":"Economic importance of manganese","titles":{"en":"Economic importance of manganese"},"summary":"Mn is brittle, so it is never used pure, only in alloys and compounds: ferromanganese (harder than steel) for railway tracks; Al-Mn alloy for soft-drink cans (resists corrosion). Compounds: MnO2 strong oxidizing agent in dry cells; KMnO4 antiseptic; MnSO4 fungicide.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ Mn هش (brittle)، عشان كده عمره ما بيُستخدم نقي، وبيُستخدم في alloys و compounds تحديدًا: الـ ferromanganese (أصلد من الـ steel) في قضبان السكة الحديد، والـ Al-Mn alloy في علب المياه الغازية (لأنه بيقاوم الـ corrosion). ومن الـ compounds: الـ MnO2 عامل مؤكسد قوي (strong oxidizing agent) في الـ dry cells، والـ KMnO4 مطهّر (antiseptic)، والـ MnSO4 مبيد فطري (fungicide). المطلوب: إنك توصّل كل واحد باستخدامه وسببه.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["المنجنيز ومركباته: استخداماتهم"]},"prereq_ids":["chem.rusting-corrosion","redox.basic","te.first-series-elements"],"in_chapter":true,"misconceptions":[{"id":"te.uses-mn.mc1","label":"Manganese is used pure.","explanation":"It is brittle; only alloys or compounds.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ Mn هش (brittle)، فمش بيُستخدم نقي؛ بيُستخدم في alloys أو compounds تحديدًا.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.uses-mn.mc2","label":"Swapping KMnO4 (antiseptic) and MnSO4.","explanation":"These two are easy to swap: $\\ce{MnSO4}$ is the fungicide, while $\\ce{KMnO4}$ is the antiseptic.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"خلّي بالك متبدّلهمش: الـ MnSO4 هو المبيد الفطري (fungicide)، أما الـ KMnO4 فهو المطهّر (antiseptic).","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"te.uses-ni","kind":"concept","title":"Economic importance of nickel","titles":{"en":"Economic importance of nickel"},"summary":"Ni: rechargeable Ni-Cd batteries; Ni-steel alloys that are hard and resist rust and acids; Ni-Cr alloys for heating coils and electric furnaces (resist corrosion at high temperature); nickel plating protects other metals and gives them a nice look; finely divided Ni is a catalyst for hydrogenation of oils.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"استخدامات الـ Ni: بطاريات الـ Ni-Cd اللي بتتشحن تاني؛ الـ Ni-steel alloys اللي بتبقى hard وبتقاوم الـ rust والـ acids؛ الـ Ni-Cr alloys في ملفات التسخين (heating coils) والأفران الكهربا (electric furnaces) عشان بتقاوم الـ corrosion في درجات الحرارة العالية؛ الطلي بالـ nickel (nickel plating) بيحمي الـ metals التانية وبيدّيها شكل حلو؛ والـ finely divided Ni بيشتغل catalyst في الـ hydrogenation of oils.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["النيكل: استخداماته"]},"prereq_ids":["chem.catalyst","chem.rusting-corrosion","te.first-series-elements"],"in_chapter":true,"misconceptions":[{"id":"te.uses-ni.mc1","label":"Ni-Cr coils are chosen because they conduct well.","explanation":"The book's reason is resistance to corrosion at high temperature.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، ده مش سبب الكتاب؛ الكتاب بيقول إنها بتتختار عشان بتقاوم الـ corrosion في درجات الحرارة العالية.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.uses-ni.mc2","label":"A lump of nickel catalyses as well as finely divided nickel.","explanation":"No. The catalysis happens at the metal's surface, and finely divided nickel has a much larger surface than one lump of the same mass, so it touches more oil and hydrogen and works better as a catalyst.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، التفاعل بيحصل على السطح؛ والـ finely divided nickel مساحة سطحه أكبر بكتير من حتة واحدة ليها نفس الكتلة، فبيلمس الزيت والـ hydrogen أكتر وبيشتغل catalyst أحسن.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"te.uses-sc-ti","kind":"concept","title":"Economic importance of scandium and titanium","titles":{"en":"Economic importance of scandium and titanium"},"summary":"Sc: spread in tiny amounts; a little Sc added to Al gives a light, very hard alloy (MiG fighter jets); added to mercury-vapour lamps to give high-quality, sunlight-like light for night TV filming. Ti: as rigid as steel but less dense; Ti-Al alloys for aircraft and space shuttles because they keep durability at high temperature while Al softens; dental implants and artificial joints because Ti is inert (the body does not reject it, no poisoning); TiO2 nanoparticles in sunscreen block UV.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ Sc موجود بكميات صغيرة جدًا ومنتشر في القشرة الأرضية. لو ضفنا كمية صغيرة من الـ Sc للـ Al بيطلع alloy خفيف وصلب جدًا (بيستخدموه في طيارات الـ MiG الحربية)، وبيتضاف كمان للـ mercury-vapour lamps عشان تدّي ضوء عالي الجودة شبه ضوء الشمس، ينفع للتصوير التلفزيوني بالليل. الـ Ti جامد زي الـ steel لكن كثافته أقل منه؛ والـ Ti-Al alloys بتدخل في الطيارات ومكوكات الفضاء لأنها بتحافظ على متانتها في درجات الحرارة العالية، في الوقت اللي الـ Al بيطرى فيه. والـ Ti بيستخدم في زراعة الأسنان والمفاصل الصناعية لأنه inert (الجسم مابيرفضوش ومابيعملش أي تسمم)، والـ TiO2 nanoparticles في كريمات الحماية من الشمس بتمنع تأثير الـ UV. المطلوب: توصّل كل استخدام بالسبب بتاعه.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["السكانديوم والتيتانيوم: بيستخدموا في إيه؟"]},"prereq_ids":["phys.em-spectrum","te.first-series-elements"],"in_chapter":true,"misconceptions":[{"id":"te.uses-sc-ti.mc1","label":"Titanium is used in implants because it is hard.","explanation":"The reason is that it is inert: not rejected, not toxic.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، السبب إن الـ titanium مادة inert: الجسم مابيرفضوش، ومابيعملش أي تسمم.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.uses-sc-ti.mc2","label":"Scandium is used pure in aircraft.","explanation":"A small amount is added to aluminum.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"الطيارات مش معمولة من scandium نقي؛ اللي بيحصل إن كمية صغيرة منه بتتضاف للـ aluminum.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.uses-sc-ti.mc3","label":"Sunscreen contains titanium metal.","explanation":"Sunscreen contains titanium dioxide, $\\ce{TiO2}$, as tiny nanoparticles that block the effect of UV on the skin: a titanium compound, not titanium metal.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، كريم الحماية من الشمس فيه TiO2 nanoparticles، يعني compound للـ titanium، مش الـ titanium metal نفسه.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"te.uses-v-cr","kind":"concept","title":"Economic importance of vanadium and chromium","titles":{"en":"Economic importance of vanadium and chromium"},"summary":"V: a small amount in steel gives a very hard, corrosion-resistant alloy (car springs); V2O5 is a colouring agent in ceramics and glass, a catalyst, and used in making strong magnets ('magnetic conductors' in the book). Cr: metal plating and leather tanning; Cr2O3 for dyes; K2Cr2O7 as an oxidizing agent.","summary_lang":"en","summary_subject_lang":"en","reveal_summary":"الـ V: كمية صغيرة منه في الـ steel بتدي alloy جامد جدًا ومقاوم للـ corrosion (بيتعمل منه الـ car springs). والـ V2O5 بيتستخدم كـ colouring agent في الـ ceramics والـ glass، وكـ catalyst، وفي صناعة الـ strong magnetic conductors (ده اسمها في الكتاب). الـ Cr: بيتستخدم في الـ metal plating والـ leather tanning؛ والـ Cr2O3 للـ dyes؛ والـ K2Cr2O7 كـ oxidizing agent. المطلوب: توصّل كل عنصر أو compound بالاستخدام بتاعه.","reveal_summary_lang":"ar-EG","reveal_summary_subject_lang":"en","aliases":{"ar":["الفاناديوم والكروم: استخداماتهم ومركباتهم"]},"prereq_ids":["chem.catalyst","chem.rusting-corrosion","redox.basic","te.first-series-elements"],"in_chapter":true,"misconceptions":[{"id":"te.uses-v-cr.mc1","label":"V2O5 is only a dye.","explanation":"It is also an important catalyst.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"لأ، الـ V2O5 مش مجرد dye: ده كمان catalyst مهم.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"},{"id":"te.uses-v-cr.mc2","label":"K2Cr2O7 is a reducing agent.","explanation":"The opposite: potassium dichromate, $\\ce{K2Cr2O7}$, is used as an oxidizing agent, not a reducing agent.","explanation_lang":"en","explanation_subject_lang":"en","reveal_explanation":"بالعكس، الـ K2Cr2O7 هو oxidizing agent، مش reducing agent.","reveal_explanation_lang":"ar-EG","reveal_explanation_subject_lang":"en"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance 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YK.periodicTable(ctx, 96, 140, 1728, {maxH: 860}) all cells dim (hp 1). Headline \"More than half of the known elements\" (Cairo 1000, 72) ON SCREEN AT FRAME 0 in the empty gap above the d-block (rows 1-3, cols 3-12). On cue(c1,\"نص\"): the d-block (violet) + the two f rows (amber) glow, the rest stays dim. Slow 2% push-in. Book p.3.","tts_text":"بصّوا على الجدول ده: أكتر من نص العناصر المعروفة قاعدين في حتة واحدة.","screen_text":"More than half of the known elements"},{"id":"c2","visual":"FB, same table, push-in continues toward the middle. On cue(c2,\"iron\"): Fe cell gold ring (YK.pulse) + YK.icon \"bridge\" (64 px) beside it + label \"iron\"; cue \"copper\": Cu ring + \"copper\"; cue \"gold\": Au ring + \"gold\". Labels Cairo 800 40, left-aligned beside each cell. One ring at a time stays lit (max 3).","tts_text":"حتى الـ iron اللي في الكباري، والـ copper، والـ gold… كلهم ساكنين هنا.","screen_text":"iron · copper · gold"},{"id":"c3","style":"curious","visual":"FB. Table dims to 30%; BIG QUESTION card centred (Cairo 1000, 96, <= 7 words) \"Who sits in the middle, and why?\" on line start; holds through the 1.0 s pause, then shrinks to a small gold tag (kept for z4).","tts_text":"مين العناصر دي؟ وليه قاعدين في النص بالذات؟","screen_text":"Who sits in the middle, and why?","pause_after_s":1},{"id":"t1","visual":"TITLE CARD (<= 4 s incl. this line). YK.titleCard({title: \"The transition elements and their series\", chip: \"Unit 1\", subtitle: \"Chapter 1: Transition Elements\"}) Cairo 1000 120; parts row under it (Cairo 800 32, 2x2 if wider than 1728): \"1 Transition elements in the periodic table · 2 Main transition elements (d-block) · 3 The four transition series · 4 Elements of the first transition series\". During the 2.5 s pause: camera move (1.2 s, no fade) into the PART 1 card (see s1l1).","tts_text":"الحلقة دي عن الـ transition elements، والـ series بتاعتهم.","screen_text":"The transition elements and their series","pause_after_s":2.5},{"id":"s1l1","visual":"PART 1/4 · te.position-in-periodic-table · objective: Locate the transition elements and name their two classes. Segment card (in t1's 2.5 s pause): YK.actCard({num: \"PART 1 OF 4\", title: \"Transition elements in the periodic table\"}) + objective line Cairo 600 40 under it; card collapses into the chip \"Transition elements in the periodic table\" (YK.chip kind segment, 96,64, left) stays on s1l1-s1l13. Line: FB table, middle region pulses once (gold outline), headline \"Between which blocks?\" in the top gap. RE-HOOK.","tts_text":"قاعدين في النص… بس بين أنهي blocks بالظبط؟","screen_text":"Between which blocks?"},{"id":"s1l2","visual":"PREREQ pt.blocks · TP (<= 20 s with s1l3). Prereq YK.chip kind prereq \"Blocks of the periodic table\" under the segment chip (y 140). Text panel (x 96-740): rule as YK.para 44, key \"last electron\" gold. Stage: same model as video-short-pt.blocks: an electron dot (cyan) flies on cue(s1l2,\"electron\") into a sublevel box labelled \"sublevel\"; box tints violet.","tts_text":"فاكرين؟ الـ sublevel اللي بياخد آخر electron هو اللي بيحدد الـ block بتاعه.","screen_text":"Block = the sublevel that receives the last electron"},{"id":"s1l3","visual":"PREREQ pt.blocks · FB table (match cut from the box). cue \"s-block\": groups 1-2 tint pink + label \"s-block\"; cue \"p-block\": groups 13-18 tint cyan + label \"p-block\". Labels Cairo 800 44 in the top gap above each block. Prereq chip fades out at line end.","tts_text":"في الجدول، الـ s-block على الشمال، والـ p-block على اليمين.","screen_text":"s-block: left · p-block: right"},{"id":"s1l4","visual":"FB same table. NEW TERM 1. cue \"transition\": the middle fills (d violet, f rows amber); a gold bracket spans between the pink and cyan blocks; label \"Transition elements\" (Cairo 1000 64) in the top gap, then \"between the (s) and (p) blocks\" (Cairo 600 40) under it. Book p.3.","tts_text":"والـ transition elements قاعدين بين الـ s-block والـ p-block، في نص الجدول.","screen_text":"Transition elements: between the (s) and (p) blocks"},{"id":"s1l5","visual":"TP. MISCONCEPTION (te.position-in-periodic-table #1). Text panel: \"A few famous metals\" (coral, Cairo 800 56) + YK.wrongMark on cue(s1l5,\"غلط\"). Stage: small table (decor, symbols off: showSymbols false) with only 3 cells lit in coral. Wrong idea held < 2 s and drawn smaller than the right idea that follows.","tts_text":"ناس كتير فاكرة إنهم شوية metals مشهورة وخلاص… غلط.","screen_text":"A few famous metals ✕"},{"id":"s1l6","visual":"FB table. d-block rows light violet one per spoken period: cue \"أربعة\" row 4, then rows 5, 6, 7 (YK.stagger 0.4 s each to cue \"سبعة\"); cue \"الصفين\" the two f rows amber. Period numbers on the left highlight gold as their row lights (periodicTable highlight.periods).","tts_text":"كل دول transition elements، من period أربعة لحد سبعة، والصفين اللي تحت كمان.","screen_text":"Periods 4 to 7 + the two rows below"},{"id":"s1l7","visual":"FB table + overlay bar in the top gap. cue \"ستين\" (alt 60): mono counter YK.counter 0 -> \"60+\" (JetBrains Mono, YK.label 72). cue \"نص\": a 100% bar (x 330-1190, h 40, label \"all known elements\" Cairo 600 36) fills violet past a gold 1/2 tick; YK.rightMark mint at the end. Book p.3.","tts_text":"دول أكتر من ستين element، يعني أكتر من نص العناصر المعروفة كلها.","screen_text":"More than 60 elements: more than half the known elements ✓"},{"id":"s1l8","visual":"TP. NEW TERM 2. Text panel list item 1 (YK.list, Cairo 800 48): \"1 - Main transition elements\" on cue \"main\". Stage: table crop (YK.camera zoom on the d-block, cells >= 70 px): d-block (periods 4-7, 10 columns) glows violet + label \"d-block\"; f rows dim. Book p.3.","tts_text":"وبيتقسموا نوعين: الأول main transition elements، ودول الـ d-block اللي في النص.","screen_text":"1 - Main transition elements: d-block"},{"id":"s1l9","visual":"TP. NEW TERM 3 (>= 1 s after term 2). List item 2 \"2 - Inner transition elements\" on cue \"inner\". Stage: camera pans down to the two detached rows, they glow amber + label \"f-block (two rows below)\". Row names (lanthanides/actinides) not drawn (not voiced).","tts_text":"والتاني inner transition elements، في الـ f-block، الصفين المنفصلين تحت.","screen_text":"2 - Inner transition elements: f-block (two rows below)"},{"id":"s1l10","visual":"FB table (shot change). f rows dim to 35%; d-block keeps a gold outline; headline \"This chapter: main transition elements only\" in the top gap. Misconception #2 handled visually: f rows marked \"inner\", not studied. Book p.3.","tts_text":"وإحنا في الباب ده هندرس الـ main transition elements لوحدهم.","screen_text":"This chapter: main transition elements only"},{"id":"s1l11","visual":"TP. PAUSE-AND-PREDICT (new case: not the short's Pu nor the lesson's U). Text panel: YK.checkPause question \"₇₈Pt sits in the middle of period 6. Main or inner?\" (question via YK.label for the subscript). Stage: table crop periods 4-7 + f rows, only Pt (period 6, group 10) pulses gold + label \"platinum\". Think ring from cueEnd(s1l11) through the 3 s pause.","tts_text":"طب الـ platinum، في نص period ستة… main ولا inner؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"₇₈Pt sits in the middle of period 6. Main or inner?","pause_after_s":3},{"id":"s1l12","visual":"TP. Answer slot \"Main: it is in the d-block\" + YK.rightMark on cue(s1l12,\"main\"); Pt cell joins the violet d-block; f rows flash amber once on cue \"الصفين\", then dim.","tts_text":"الإجابة main، عشان هو في الـ d-block، مش في الصفين اللي تحت.","screen_text":"Main transition element (d-block) ✓"},{"id":"s1l13","visual":"MICRO-RECAP · TP. YK.takeaway({title: \"Transition Elements in the Periodic Table\", line: \"Between the s- and p-blocks: main = d-block\", t, pulse: [{word: \"s-\", at: cue(s1l13,\"s-block\")}, {word: \"p-blocks\", at: cue(s1l13,\"p-block\")}, {word: \"main\", at: cue(s1l13,\"main\")}]}) in the text panel; stage keeps the small table with the d-block violet.","tts_text":"الـ transition elements بين الـ s-block والـ p-block، والـ main هما الـ d-block كله.","screen_text":"Between the s- and p-blocks: main = d-block"},{"id":"s1l14","visual":"SO-WHAT · FB. Question \"So how is the d-block built?\" (Cairo 1000 64, top gap); camera push (1.2 s) from the full table into the 10 d-block columns (periods 4-7). Segment chip out at line end. In the 2.5 s pause: PART 2 card (match cut on the columns).","tts_text":"طيب الـ d-block نفسه، متقسّم إزاي من جوه؟","screen_text":"So how is the d-block built?","pause_after_s":2.5},{"id":"s2l1","visual":"PART 2/4 · te.d-block-groups · objective: Explain why the d-block has ten columns and name its groups. Segment card in s1l14's pause: YK.actCard({num: \"PART 2 OF 4\", title: \"Main transition elements (d-block)\"}) + objective; collapses into the chip \"Main transition elements (d-block)\" stays on s2l1-s2l14. Line (FB, d-block close-up: periodicTable labels {periods:true, groups:false}, YK.camera so the 10 columns span x 300-1620, cells >= 120 px): cue \"group\": 8 tags IIIB, IVB, VB, VIB, VIIB, VIII, IB, IIB drop above the columns (custom YK.label 40 mono, VIII one wide tag); cue \"columns\": columns numbered 1-10 under the block; the mismatch \"8 ≠ 10\" in gold. RE-HOOK (misconception #2: 8 B-groups -> 8 columns).","tts_text":"بصّوا: الـ d-block فيه تمن group labels بس… وعشر columns. إزاي؟","screen_text":"8 group labels. 10 columns?"},{"id":"s2l2","visual":"PREREQ atom.sublevels · TP (<= 8 s). ONE prereq chip \"Energy sublevels (s, p, d, f)\" (no second \"Orbitals\" chip). Stage: YK.electronBoxes 5 boxes, label \"d sublevel\" (same model as the shorts); on cue \"اتنين\" each box gets ↑↓ in turn (fill 0->1 over 1.5 s); formula \"5 × 2 = 10\" (YK.formula 56) in the text panel.","tts_text":"فاكرين؟ الـ d sublevel خمس orbitals، كل واحد فيه اتنين electrons بالكتير.","screen_text":"d sublevel: 5 orbitals × 2 = 10 electrons"},{"id":"s2l3","visual":"TP. Text panel: book sentence \"Electrons occupy the d sublevel in sequence\" (YK.para 44, key \"in sequence\"). Stage: the 5 boxes empty, then fill one electron at a time (Hund order 1 -> 10) from cue \"بتملا\" over 3 s; mono counter 1 -> 10 beside them. Book p.3.","tts_text":"وفي الـ main transition elements، الـ electrons بتملا الـ d sublevel بالترتيب.","screen_text":"Electrons occupy the d sublevel in sequence"},{"id":"s2l4","visual":"FB (match cut). The 10 electrons leave the boxes (YK.flyer dots, staggered 0.15 s) and land one in each of the 10 d-block columns on cue \"columns\"; columns light violet left -> right; label \"vertical columns\" above. Book p.3: \"Since the d-sublevel can take up to ten electrons, it contains ten vertical columns\".","tts_text":"وعشان بياخد لحد عشرة electrons، الـ d-block فيه عشر vertical columns بالظبط.","screen_text":"Up to 10 electrons → 10 vertical columns"},{"id":"s2l5","visual":"FB d-block close-up. YK.formula tags (mono 48, book notation \"ns^2 (n-1)d^1\", \"ns^2 (n-1)d^10\") pop above column 1 on cue \"أول\" and above column 10 on cue \"آخر\". NO per-column d²…d⁹ tags (false for Cr and Cu). Book p.3.","tts_text":"أول column، الـ d sublevel فيه electron واحد… وآخر column، فيه عشرة كاملين.","screen_text":"First column: ns² (n−1)d¹ … last column: ns² (n−1)d¹⁰"},{"id":"s2l6","visual":"FB close-up. The 8 hook tags reset; labels \"(3) IIIB\", \"(4) IVB\", \"(5) VB\", \"(6) VIB\", \"(7) VIIB\" land on columns 1-5, one per spoken number (cues \"تلاتة\", \"أربعة\", \"خمسة\", \"ستة\", \"سبعة\"; alt digits), left -> right. \"B\" never spoken.","tts_text":"من الشمال لليمين: group تلاتة، أربعة، خمسة، ستة، وسبعة.","screen_text":"(3) IIIB · (4) IVB · (5) VB · (6) VIB · (7) VIIB"},{"id":"s2l7","visual":"TP (shot change). MISCONCEPTION (te.d-block-groups #1). Text panel \"Group VIII = 1 column\" coral + YK.wrongMark on cue(s2l7,\"غلط\"). Stage: a VIII tag squeezed over a single column, coral, < 2 s, smaller than the correction.","tts_text":"بعدها group تمانية… وناس كتير فاكراه column واحد. غلط.","screen_text":"Group VIII = 1 column ✕"},{"id":"s2l8","visual":"FB close-up. The VIII tag stretches over columns 6-8 with a bracket; \"(8)\", \"(9)\", \"(10)\" appear on their spoken numbers (cues \"تمانية\", \"وتسعة\", \"وعشرة\"); YK.rightMark mint. Book p.3.","tts_text":"الحقيقة إن group تمانية تلات columns: تمانية، وتسعة، وعشرة.","screen_text":"Group VIII: three columns (8), (9), (10) ✓"},{"id":"s2l9","visual":"FB close-up. cue \"similar\": horizontal gold band across the period-4 VIII cells Fe, Co, Ni; the cells below them (Ru…Pt) dim to 35%; label \"similar horizontally\" in gold. Misconception #3 (resemble the ones below) answered by the dim. Book p.3.","tts_text":"وعناصر group تمانية similar horizontally: بتشبه جيرانها في الصف، أكتر من اللي تحتها.","screen_text":"Similar horizontally, more than the elements below"},{"id":"s2l10","visual":"FB close-up. \"(11) IB\" on cue \"حداشر\", \"(12) IIB\" on cue \"اتناشر\" land on columns 9 and 10; all 8 labels now sit over 10 columns: the hook resolved, \"8 labels → 10 columns\" ✓ in gold.","tts_text":"وبعدهم group حداشر، وفي الآخر group اتناشر.","screen_text":"(11) IB · (12) IIB"},{"id":"s2l11","visual":"FB close-up. Column 10 gets a dashed outline; note in the book's wording under the block (Cairo 600 36, textDim): \"IIB: from one point of view, not considered transition elements\". No reason given (definition is unit te-configuration). Book p.3.","tts_text":"والكتاب بيقول إن group اتناشر مش بيتحسب transition، من وجهة نظر معينة.","screen_text":"IIB: from one point of view, not considered transition elements"},{"id":"s2l12","visual":"TP. PAUSE-AND-PREDICT (new case; the short used V). Text panel YK.checkPause question. Stage: small d-block strip with the VIII bracket, column (9) pulses gold + label \"cobalt\"; 5 empty boxes labelled \"3d\" under it. Think ring through the 3 s pause.","tts_text":"طب الـ cobalt في group تسعة. كام electron في three d؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"₂₇Co is in group (9). How many 3d electrons?","pause_after_s":3},{"id":"s2l13","visual":"TP. Answer: columns 1-7 count up left -> right to Co on cue \"سبعة\" (mono 1…7); the 3d boxes fill to 7 (Hund order); answer slot \"3d⁷: seventh d-block column\" + YK.rightMark. No [Ar] 4s² prefix (configurations are unit te-configuration).","tts_text":"الإجابة سبعة، عشان الـ cobalt في سابع column من الشمال.","screen_text":"₂₇Co: 3d⁷ (7th d-block column) ✓ · Cr and Cu break this pattern (4s¹)"},{"id":"s2l14","visual":"MICRO-RECAP · TP. YK.takeaway({title: \"Main Transition Elements (d-block)\", line: \"10 electrons → 10 columns; VIII = 3 columns\", pulse on \"10\" at cue(s2l14,\"عشرة\"), \"columns\" at cue \"columns\", \"VIII\" at cue \"تمانية\"}); stage: the labelled 10-column strip.","tts_text":"عشرة electrons في الـ d sublevel، يعني عشر columns، و group تمانية تلاتة منهم.","screen_text":"10 electrons → 10 columns; VIII = 3 columns · Cr and Cu break this pattern (4s¹)"},{"id":"s2l15","visual":"SO-WHAT · FB. Columns dim; four horizontal bands (periods 4-7) sweep left -> right on cue \"الصفوف\". Segment chip out. Then straight into m1 (0.8 s beat).","tts_text":"كده عرفنا العشر columns… طب الصفوف الأفقية بقى؟","screen_text":"10 columns. And the rows?","pause_after_s":0.8},{"id":"m1l1","visual":"MID-EPISODE RECAP 1 (~3:40-4:20) · FB. YK.flow({layout: \"row\", area: {x: 96, y: 380, w: 1728, h: 320}, node: {size: 44}}) on ink; node 1 \"Between s- and p-blocks\" (+ tiny table glyph) on cue(m1l1,\"transition\"). Header \"So far\" Cairo 800 40 top-left (no segment chip).","tts_text":"نلم الحكاية: الـ transition elements بين الـ s-block والـ p-block، في النص.","screen_text":"The story so far · Transition elements: between s- and p-blocks"},{"id":"m1l2","visual":"FB flow: arrow + node 2 \"d sublevel holds 10\" (5-box glyph) on cue \"d\".","tts_text":"جواهم الـ electrons بتملا الـ d sublevel، اللي بياخد عشرة.","screen_text":"d sublevel holds 10"},{"id":"m1l3","visual":"FB flow: arrow + node 3 \"10 columns: IIIB → IIB\" on cue \"columns\"; nodes 1-3 glow once together at line end. In the 2.5 s pause: camera tilts from node 3 to the d-block rows = PART 3 card.","tts_text":"فبقوا عشر columns، من group تلاتة لحد group اتناشر.","screen_text":"10 columns: IIIB → IIB","pause_after_s":2.5},{"id":"s3l1","visual":"PART 3/4 · te.transition-series · objective: Link each transition series to its period and d sublevel. Segment card in m1l3's pause: YK.actCard({num: \"PART 3 OF 4\", title: \"The four transition series\"}) + objective; collapses into the chip \"The four transition series\" stays on s3l1-s3l16. Line (FB table): period-4 d row outlined gold; tag \"3d\" (mono 56, gold) on cue \"three\", struck-through \"4d?\" (textDim) on cue \"four\". RE-HOOK.","tts_text":"غريبة: الصف اللي في period أربعة بيملا three d، مش four d. ليه؟","screen_text":"Period 4 → 3d. Why not 4d?"},{"id":"s3l2","visual":"PREREQ atom.aufbau · TP (<= 8 s). Prereq chip \"Aufbau principle (order of filling)\". Stage: YK.flow row of 4 sublevel nodes \"3p\" \"4s\" \"3d\" \"4p\" (x 790-1824), each lit on its spoken word (\"three\", \"four\", \"three\", \"four\" needles in order). Order only: no energy axis, no \"lower energy\" claim (G43).","tts_text":"افتكروا الـ Aufbau principle: بعد three p ييجي four s، والـ three d بعدها.","screen_text":"… 3p → 4s → 3d → 4p"},{"id":"s3l3","visual":"FB table, period 4. cue \"calcium\": Ca cell rings pink; a 4s box with ↑↓ beside it (YK.electronBoxes, label \"4s\"; NOT configStrip, which prints 3d^0 for Ca). cue \"scandium\": first 3d electron flies into a 3d box beside Sc; labels \"₂₀Ca: 4s² full\" and \"₂₁Sc: 3d¹\". Book p.4 \"after calcium\".","tts_text":"بعد ما الـ calcium يقفل four s، الـ scandium بيفتح three d هنا.","screen_text":"₂₀Ca: 4s² full → ₂₁Sc: 3d¹"},{"id":"s3l4","visual":"TP. NEW TERM 1. The segment's one definition card: YK.termCard({term: \"Transition series\", def: \"The elements in which a d sublevel is filled successively\", keys: [\"filled successively\"]}) in the text panel on cue \"series\". Stage: period-4 d row bracketed gold. Book p.4 wording (\"the sublevel (3d) is filled successively\").","tts_text":"عشان كده كل transition series هي صف بيتملي فيه d sublevel واحد بالترتيب.","screen_text":"Transition series: a row where a d sublevel is filled successively"},{"id":"s3l5","visual":"FB table. Custom row bracket 1 (violet, from periodicTable rects; NOT dBlockZoom series, which staggers all 4) over period 4; tags \"1st\", \"3d\", \"period 4\" appear on cues \"first\", \"three\", \"أربعة\". Book p.4.","tts_text":"أول واحدة، الـ first transition series، بتملا three d في period أربعة.","screen_text":"First transition series: 3d · period 4"},{"id":"s3l6","visual":"TP. Stage: two YK.elementCard (w 340) \"Sc\" on cue \"scandium\" and \"Zn\" on cue \"zinc\", config passed explicitly in book form config: \"4s^2 3d^1\" / \"4s^2 3d^10\" (not the default [Ar] form); arrow between them. Text panel: \"First transition series\" + \"Sc → Zn\". Book p.4.","tts_text":"وبتبدأ بالـ scandium واحد وعشرين، وتخلص بالـ zinc تلاتين.","screen_text":"₂₁Sc (4s² 3d¹) → ₃₀Zn (4s² 3d¹⁰)"},{"id":"s3l7","visual":"FB table. Bracket 2 under bracket 1 (same style); tags \"2nd · 4d · period 5\" on cue \"four\"; end cells Y and Cd ring gold with labels \"yttrium 39\" (cue \"yttrium\") and \"cadmium 48\" (cue \"cadmium\"). Book p.4.","tts_text":"التانية four d، في period خمسة… من الـ yttrium للـ cadmium، عشر عناصر برضه.","screen_text":"Second series: 4d · period 5 · ₃₉Y → ₄₈Cd"},{"id":"s3l8","visual":"FB table. Bracket 3 over period 6 starting at the group-3 placeholder \"57-71\"; cue \"lanthanum\": La rings gold IN THE BOTTOM ROW (where the kit table and the book figure put it) with a thin dashed connector to the placeholder; cue \"mercury\": Hg rings gold. Labels \"lanthanum 57\", \"mercury 80\". Book p.4; lesson: \"On this table, La sits in the bottom row\".","tts_text":"التالتة five d، في period ستة: من الـ lanthanum، والـ mercury آخرها.","screen_text":"Third series: 5d · period 6 · ₅₇La → ₈₀Hg"},{"id":"s3l9","visual":"FB table. Bracket 4 over period 7; tags \"4th · 6d · period 7\" on cue \"six\". No end elements (book names none). Book p.5.","tts_text":"والرابعة بتملا six d، في period سبعة، آخر صف في الجدول.","screen_text":"Fourth series: 6d · period 7"},{"id":"s3l10","visual":"MID-SEGMENT CHECK (segment > 120 s, E1a) · TP. Text panel question (Cairo 800 48); stage: brackets 1-3 pulse, cells hidden behind \"?\" tiles; small YK.thinkRing through the 1.2 s pause.","tts_text":"سؤال سريع: كام element في كل series من التلاتة الأولانيين؟","screen_text":"Quick check: how many elements in each of the first three series?","pause_after_s":1.2},{"id":"s3l11","visual":"FB table. CONNECTION to Part 2: the 10 column tags (IIIB … IIB) reappear above the brackets on cue \"columns\"; rows 1-3 each count \"10\" (mono) on cue \"عشر\"; answer ✓. Book p.4 \"consists of ten elements\".","tts_text":"والتلات series الأولانيين، كل واحدة فيها عشر عناصر… قدّ العشر columns بالظبط.","screen_text":"First three series: ten elements each"},{"id":"s3l12","visual":"WORKED EXAMPLE · TP. Text panel: 3 notation rows built one per cue (YK.label mono 48): \"₂₁Sc: 4s² 3d¹\" (cue \"three\"), \"₃₉Y: 5s² 4d¹\" (cue \"four\"), \"₅₇La: 6s² 5d¹\" (cue \"five\"); then the pattern \"ns² (n−1)d¹\" in gold under them. Stage: the 3 first cells of brackets 1-3 glow. Book p.4 configurations.","tts_text":"وأول عنصر في كل واحدة: three d واحد، four d واحد، five d واحد.","screen_text":"ns² (n−1)d¹"},{"id":"s3l13","visual":"TP. MISCONCEPTION (te.transition-series #1). Text panel: \"Period 4 → 4d\" coral + YK.wrongMark on cue \"غلط\" (< 2 s); then on cue \"بواحد\" the rows \"4 → 3d\", \"5 → 4d\", \"6 → 5d\", \"7 → 6d\" (mono 48) and the rule \"Period n → (n − 1)d\" gold + YK.rightMark. Stage: the four brackets with their sublevel tags.","tts_text":"ناس كتير بتقول period أربعة يبقى four d… غلط، الـ d sublevel أقل بواحد.","screen_text":"Period 4 → 4d ✕ · Period n → (n − 1)d ✓"},{"id":"s3l14","visual":"FB table (shot change). PAUSE-AND-PREDICT (new case; the short used Hg). YK.checkPause question in the top gap; Zr cell (period 5, group 4) pulses gold + label \"zirconium\"; think ring through the 3 s pause.","tts_text":"طب الـ zirconium، في period خمسة. بيملا أنهي d sublevel؟ وقّفوا ثانية وفكّروا.","screen_text":"₄₀Zr is in period 5. Which d sublevel fills?","pause_after_s":3.9},{"id":"s3l15","visual":"FB table. Answer on cue \"four\": formula \"(5 − 1)d = 4d\" (mono 56); Zr cell slides into bracket 2 labelled \"second series\"; YK.rightMark.","tts_text":"الإجابة four d، خمسة ناقص واحد، يعني الـ second series هي مكانه.","screen_text":"4d: (5 − 1)d → second series ✓"},{"id":"s3l16","visual":"MICRO-RECAP · TP. YK.takeaway({title: \"The Four Transition Series\", line: \"Period n fills the (n − 1)d sublevel\", formula: \"3d · 4d · 5d · 6d\"}) with the four sublevels pulsing left -> right from cue \"بواحد\" (YK.stagger 0.3 s; the tts states the rule, it does not list 3d-6d); stage: the 4 brackets.","tts_text":"الخلاصة: كل period بيملا الـ d sublevel اللي رقمه أقل بواحد.","screen_text":"Period n fills the (n − 1)d sublevel"},{"id":"s3l17","visual":"SO-WHAT · FB. Brackets 2-4 dim; YK.dBlockZoom p 0 -> 1 from cue \"first\" (1.2 s): row 1 becomes the 10-tile strip Sc -> Zn (stage of Part 4). Segment chip out. In the 2.5 s pause: PART 4 card over the strip.","tts_text":"من الأربعة دول، الباب كله بيركز على الـ first series. يلا نقرّب.","screen_text":"First transition series: zoom in","pause_after_s":2.5},{"id":"s4l1","visual":"PART 4/4 · te.first-series-elements · objective: Recognize the elements of the first transition series. Segment card in s3l17's pause: YK.actCard({num: \"PART 4 OF 4\", title: \"Elements of the first transition series\"}) + objective; collapses into the chip \"Elements of the first transition series\" stays on s4l1-s4l18. Line (FB): dBlockZoom strip at p 1, tiles show Z only (\"?\" for symbols, custom tiles), headline \"Ten elements. Can you name them in order?\" above. RE-HOOK.","tts_text":"العشر elements دول مين بالظبط؟ تقدروا تعدّوهم بالترتيب من غير غلطة؟","screen_text":"Ten elements. Can you name them in order?"},{"id":"s4l2","visual":"PREREQ atom.electron-configuration-writing · TP (<= 8 s). Prereq chip \"Writing electronic configurations\". Text panel: rule (YK.para 44). Stage: \"1s^2 2s^2 2p^6 3s^2 3p^6\" (mono 48) collapses into \"[Ar]\" on cue \"noble\" (same model as the short).","tts_text":"افتكروا الـ short form: الـ noble gas اللي قبل العنصر بين قوسين، والباقي بعده.","screen_text":"Short form: [noble gas] + the rest"},{"id":"s4l3","visual":"WORKED EXAMPLE · TP (book p.4 configuration in short form). Stage: YK.configStrip({Z: 21, size: 110}) building on cue \"scandium\" ([Ar] chip, 4s ↑↓, one 3d electron flying in), live label \"[Ar] 4s^2 3d^1\". Text panel: \"₂₁Sc\" + \"first in the row\". Strip tile Sc highlighted at the top.","tts_text":"زي الـ scandium: argon، four s two، three d one… أول واحد في الصف.","screen_text":"₂₁Sc: [Ar] 4s² 3d¹"},{"id":"s4l4","visual":"WORKED EXAMPLE · TP. Separate YK.configStrip({Z: 30, size: 110}) (do NOT step Z through 22-29: that draws Cr/Cu); 3d boxes fill to ↑↓ ×5 from cue \"zinc\"; label \"[Ar] 4s^2 3d^10\"; \"full\" tag mint on cue \"عالآخر\".","tts_text":"ولحد الـ zinc: argon، four s two، three d ten… كده اتملت عالآخر.","screen_text":"₃₀Zn: [Ar] 4s² 3d¹⁰"},{"id":"s4l5","visual":"FB. YK.dBlockZoom strip (p 1, stripW 1555, names 1; tiles ~155 px; names staggered on 2 lines by the kit). highlight grows per spoken name: Sc (cue \"scandium\"), Ti (\"titanium\"), V (\"vanadium\"). NOT 10 elementCards (w < 300 in 16:9).","tts_text":"يلا نعدّهم بالترتيب: scandium، titanium، vanadium، دول التلاتة الأولانيين.","screen_text":"Sc · Ti · V"},{"id":"s4l6","visual":"FB strip. Cr, Mn, Fe light on their names; on cue \"نجم\" the Fe tile gets a 0.6 s steel glint sweep (no forward content).","tts_text":"وبعدهم chromium، manganese، iron… وده نجم الباب كله.","screen_text":"Cr · Mn · Fe"},{"id":"s4l7","visual":"FB strip. Co, Ni, Cu, Zn light on their names; on cue \"عشرة\" mono counter \"10\" above the strip. Book p.5 list.","tts_text":"وفي الآخر cobalt، nickel، copper، zinc… عشرة بالظبط.","screen_text":"Co · Ni · Cu · Zn"},{"id":"s4l8","visual":"FB strip. CONNECTION to Part 2: dBlockZoom groups 0 -> 1 on line start (book labels, VIII spans Fe-Ni); YK.pulse on the Sc tag at cue \"scandium\" and the Zn tag at cue \"zinc\".","tts_text":"وكل واحد في column: الـ scandium في group تلاتة، والـ zinc في group اتناشر.","screen_text":"₂₁Sc: group (3) IIIB … ₃₀Zn: group (12) IIB"},{"id":"s4l9","visual":"MID-SEGMENT CHECK (segment > 120 s) · FB strip. The Co/Ni tiles lift and hover swapped (custom tiles), \"?\" between them; small YK.thinkRing through the 1.2 s pause.","tts_text":"سؤال سريع: الـ cobalt ولا الـ nickel، مين الأول؟","screen_text":"Quick check: Co or Ni, which comes first?","pause_after_s":1.2},{"id":"s4l10","visual":"FB strip. MISCONCEPTION (te.first-series-elements #2). Cr/Mn pair also tries to swap (coral ✕, < 1 s), then both pairs snap back on cue \"مش\"; Z shown gold \"24 < 25\", \"27 < 28\"; YK.rightMark.","tts_text":"خلّوا بالكم: الـ chromium قبل الـ manganese، والـ cobalt قبل الـ nickel… مش العكس.","screen_text":"In order of atomic number: Cr before Mn, Co before Ni"},{"id":"s4l11","visual":"TP. Stage: YK.chart({type: 'bar', data: book table p.5 (Sc 0.0026, Ti 0.66, V 0.02, Cr 0.014, Mn 0.11, Fe 5, Co 0.003, Ni 0.0089, Cu 0.0068, Zn 0.0078), yLabel: '% wt', values: true, highlight: ['Fe'], grow}) grows from cue \"earth's\"; Fe bar gold. Text panel headline \"% wt in the earth's crust\". Values from the book only.","tts_text":"في الـ earth's crust، الـ iron لوحده خمسة في المية.","screen_text":"% wt in the earth's crust: Fe 5"},{"id":"s4l12","visual":"TP. Second YK.chart of the five values < 0.01 in book order (Sc, Co, Ni, Cu, Zn), yRange [0, 0.01], yLabel '% wt', values true, highlight ['Sc','Co'] on cue \"scandium\" / \"cobalt\"; transition = the big chart slides left and fades. Book p.5.","tts_text":"أما الـ scandium والـ cobalt، فدول من أندرهم خالص.","screen_text":"Sc 0.0026 · Co 0.003"},{"id":"s4l13","visual":"FB (shot change). One 100% bar across the frame (x 196-1724, h 90) labelled \"earth's crust\"; on cue \"سبعة\" a 7% violet segment fills from the left + label \"nearly 7%\" (YK.label so the digit is mono). Book p.5.","tts_text":"والعشرة كلهم مع بعض، تقريبًا سبعة في المية بس.","screen_text":"All ten: nearly 7% of the weight of the earth's crust"},{"id":"s4l14","visual":"TP. MISCONCEPTION (te.first-series-elements #1). Text panel \"Abundant = important\" coral + YK.wrongMark on cue \"غلط\", < 2 s; stage keeps the 7% bar small.","tts_text":"ناس كتير فاكرة إن العنصر المهم هو اللي موجود بكميات كبيرة… غلط.","screen_text":"Abundant = important ✕"},{"id":"s4l15","visual":"TP. Text panel: \"Nearly 7%, but high economic importance\" with \"high economic importance\" gold via YK.marker on cue \"economic\"; YK.rightMark; stage: 7% bar beside a gold star glyph (small amount, big value). Book p.5.","tts_text":"الكتاب بيقول إن ليهم economic importance عالية، رغم إنهم قليلين.","screen_text":"Nearly 7%, but high economic importance ✓"},{"id":"s4l16","visual":"FB strip (shot change). PAUSE-AND-PREDICT (new case; the short used 27). Tiles flip to Z only (21-30, symbols and names hidden, custom tiles); YK.checkPause question above the strip; think ring through the 3 s pause.","tts_text":"أنهي عنصر الـ atomic number بتاعه خمسة وعشرين؟ فكّروا. <long pause>","screen_text":"Which element has atomic number 25?","pause_after_s":3},{"id":"s4l17","visual":"FB strip. Tile 25 flips back to \"Mn / Manganese\" on cue \"manganese\" + YK.rightMark; tile 24 \"Cr\" glows on cue \"chromium\".","tts_text":"الإجابة manganese، اللي بعد الـ chromium أربعة وعشرين.","screen_text":"₂₅Mn: manganese (after ₂₄Cr) ✓"},{"id":"s4l18","visual":"MICRO-RECAP · TP. YK.takeaway({title: \"Elements of the First Transition Series\", line: \"Sc → Zn: scarce, but high economic importance\", pulse: \"Sc\" at cue \"scandium\", \"Zn\" at cue \"zinc\", \"importance\" at cue \"importance\"}); stage: the 10-tile strip.","tts_text":"الـ first series، من الـ scandium للـ zinc: قليلين، بس ليهم economic importance عالية.","screen_text":"Sc → Zn: scarce, but high economic importance"},{"id":"s4l19","visual":"SO-WHAT into the closing · FB. Camera pulls back from the strip to the full table (1.2 s); segment chip out; headline \"Putting it all together\" in the top gap.","tts_text":"كده الصورة كاملة. يلا نربطها ببعض.","screen_text":"Putting it all together"},{"id":"z1","visual":"CLOSING SUMMARY · FB. YK.flow row (area x 96-1824, y 360-680, node size 40) of 5 nodes, built left -> right: nodes 1-3 (same labels as m1) light on cues \"النص\", \"d-block\", \"columns\" (in that spoken order).","tts_text":"نلم الحلقة: في النص بين الـ s-block والـ p-block، الـ d-block بعشر columns كاملين.","screen_text":"Between s- and p-blocks · d-block · 10 columns: IIIB → IIB"},{"id":"z2","visual":"FB flow: arrow + node 4 \"4 series: 3d → 6d\" on cue \"series\".","tts_text":"وأربع transition series، من three d لحد six d، صف ورا صف.","screen_text":"4 series: 3d → 6d"},{"id":"z3","visual":"FB flow: arrow + node 5 \"First series: Sc → Zn\" in gold on cue \"first\"; the whole chain glows once.","tts_text":"والـ first series، من الـ scandium للـ zinc، هي بطلة الباب ده.","screen_text":"First series: Sc → Zn"},{"id":"z4","visual":"TP. BIG QUESTION ANSWERED (part 1). The cold-open tag \"Who sits in the middle, and why?\" returns top-left of the text panel; answer under it on cue \"main\" (Cairo 800 44). Stage: small table, d-block violet.","tts_text":"فمين اللي في النص؟ الـ main transition elements، اللي بيملوا الـ d sublevel بالترتيب.","screen_text":"The middle: main transition elements, filling the d sublevel"},{"id":"z5","visual":"FB (part 2: why). Period-4 row only, large: an electron path runs K, Ca (4s, pink) on cue \"four\" -> Sc…Zn (3d, violet) on cue \"three\" -> Ga…Kr (4p, cyan) on cue \"four\" (2nd), left -> right, so the d-block sits between s and p. Order only, no energy claim (G43).","tts_text":"وليه في النص؟ عشان three d بتتملي بعد four s، وقبل four p بالظبط.","screen_text":"Period 4: 4s → 3d → 4p"},{"id":"z6","visual":"RECALL 1/3 (Part 1 idea, new case) · TP. YK.checkPause question; stage: table with only Ce (first f row) pulsing gold + label \"cerium\"; think ring through the 3 s pause.","tts_text":"أول سؤال: الـ cerium في الصفين اللي تحت… main ولا inner؟ فكّروا. <long pause>","screen_text":"₅₈Ce is in the two rows below. Main or inner?","pause_after_s":3},{"id":"z7","visual":"TP. Answer \"Inner: it is in the f-block\" + YK.rightMark on cue \"inner\"; f rows glow amber.","tts_text":"الإجابة: عنصر inner transition، عشان الـ cerium في الـ f-block مش الـ d-block خالص.","screen_text":"Inner transition element (f-block) ✓"},{"id":"z8","visual":"RECALL 2/3 (Part 2 idea, self-explanation) · FB. YK.checkPause question \"Why does the d-block have 10 columns?\" over the 10 d-block columns; think ring through the 3 s pause.","tts_text":"وقولوها في جملة: ليه عدد الـ columns في الـ d-block عشرة؟ <long pause>","screen_text":"Why does the d-block have 10 columns?","pause_after_s":3},{"id":"z9","visual":"FB. Answer: five d boxes fill ↑↓ ×5 on cue \"عشرة\" and morph into the 10 columns (the episode's core model, loop closed); YK.rightMark. Book p.3.","tts_text":"عشان الـ d sublevel بياخد عشرة electrons بالكتير.","screen_text":"The d sublevel takes up to 10 electrons ✓"},{"id":"z10","visual":"RECALL 3/3 (Part 3 idea, new case) · FB table. YK.checkPause in the top gap; Ag cell (period 5, group 11) pulses gold + label \"silver\"; think ring through the 3 s pause.","tts_text":"آخر سؤال: الـ silver، في period خمسة. في أنهي transition series؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"₄₇Ag is in period 5. Which transition series?","pause_after_s":3},{"id":"z11","visual":"FB table. Answer on cue \"second\": Ag slides into bracket 2; \"(5 − 1)d = 4d\" (mono 56); YK.rightMark.","tts_text":"في الـ second series: period خمسة يعني four d، خمسة ناقص واحد.","screen_text":"Second series: 4d ✓"},{"id":"z12","visual":"TEASER (labelled last line only) · FB strip of 10 tiles; label \"Next episode:\" (Cairo 800 40, textDim) + \"Economic importance of the first transition series\" (Cairo 1000 64). No subscribe. Hold 0.8 s tail.","tts_text":"الحلقة الجاية: الـ economic importance بتاعة العشرة دول.","screen_text":"Next episode: Economic importance of the first transition series"}],"logline":"More than half of the known elements sit in the middle of the periodic table. Who are they, and why there? 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على الجدول ده أكتر من نص العناصر\nالمعروفة قاعدين في حتة واحدة\nحتى الـ iron اللي في الكباري والـ copper\nوالـ gold كلهم ساكنين هنا\nمين العناصر دي وليه قاعدين في النص بالذات\nالحلقة دي عن الـ transition elements والـ\nseries بتاعتهم\nقاعدين في النص بس بين أنهي blocks بالظبط\nفاكرين الـ sublevel اللي بياخد آخر\nelectron هو اللي بيحدد الـ block بتاعه\nفي الجدول الـ s-block على الشمال والـ\np-block على اليمين\nوالـ transition elements قاعدين بين الـ\ns-block والـ p-block في نص الجدول\nناس كتير فاكرة إنهم شوية metals مشهورة\nوخلاص غلط\nكل دول transition elements من period أربعة\nلحد سبعة والصفين اللي تحت كمان\nدول أكتر من ستين element يعني أكتر من نص\nالعناصر المعروفة كلها\nوبيتقسموا نوعين الأول main transition\nelements ودول الـ d-block اللي في النص\nوالتاني inner transition elements في الـ\nf-block الصفين المنفصلين تحت\nوإحنا في الباب ده هندرس الـ main\ntransition elements لوحدهم\nطب الـ platinum في نص period ستة main ولا\ninner وقّفوا ثانية وفكّروا\nالإجابة main عشان هو في الـ d-block مش في\nالصفين اللي تحت\nالـ transition elements بين الـ s-block\nوالـ p-block والـ main هما الـ d-block كله\nطيب الـ d-block نفسه متقسّم إزاي من جوه\nبصّوا الـ d-block فيه تمن group labels بس\nوعشر columns إزاي\nفاكرين الـ d sublevel خمس orbitals كل واحد\nفيه اتنين electrons بالكتير\nوفي الـ main transition elements الـ\nelectrons بتملا الـ d sublevel بالترتيب\nوعشان بياخد لحد عشرة electrons الـ d-block\nفيه عشر vertical columns بالظبط\nأول column الـ d sublevel فيه electron\nواحد وآخر column فيه عشرة كاملين\nمن الشمال لليمين group تلاتة أربعة خمسة\nستة وسبعة\nبعدها group تمانية وناس كتير فاكراه column\nواحد غلط\nالحقيقة إن group تمانية تلات columns\nتمانية وتسعة وعشرة\nوعناصر group تمانية similar horizontally\nبتشبه جيرانها في الصف أكتر من اللي تحتها\nوبعدهم group حداشر وفي الآخر group اتناشر\nوالكتاب بيقول إن group اتناشر مش بيتحسب\ntransition من وجهة نظر معينة\nطب الـ cobalt في group تسعة كام electron\nفي three d وقّفوا ثانية وفكّروا\nالإجابة سبعة عشان الـ cobalt في سابع\ncolumn من الشمال\nعشرة electrons في الـ d sublevel يعني عشر\ncolumns و group تمانية تلاتة منهم\nكده عرفنا العشر columns طب الصفوف الأفقية\nبقى\nنلم الحكاية الـ transition elements بين\nالـ s-block والـ p-block في النص\nجواهم الـ electrons بتملا الـ d sublevel\nاللي بياخد عشرة\nفبقوا عشر columns من group تلاتة لحد group\nاتناشر\nغريبة الصف اللي في period أربعة بيملا\nthree d مش four d ليه\nافتكروا الـ Aufbau principle بعد three p\nييجي four s والـ three d بعدها\nبعد ما الـ calcium يقفل four s الـ\nscandium بيفتح three d هنا\nعشان كده كل transition series هي صف بيتملي\nفيه d sublevel واحد بالترتيب\nأول واحدة الـ first transition series\nبتملا three d في period أربعة\nوبتبدأ بالـ scandium واحد وعشرين وتخلص\nبالـ zinc تلاتين\nالتانية four d في period خمسة من الـ\nyttrium للـ cadmium عشر عناصر برضه\nالتالتة five d في period ستة من الـ\nlanthanum والـ mercury آخرها\nوالرابعة بتملا six d في period سبعة آخر صف\nفي الجدول\nسؤال سريع كام element في كل series من\nالتلاتة الأولانيين\nوالتلات series الأولانيين كل واحدة فيها\nعشر عناصر قد العشر columns بالظبط\nوأول عنصر في كل واحدة three d واحد four d\nواحد five d واحد\nناس كتير بتقول period أربعة يبقى four d\nغلط الـ d sublevel أقل بواحد\nطب الـ zirconium في period خمسة بيملا أنهي\nd sublevel وقّفوا ثانية وفكّروا\nالإجابة four d خمسة ناقص واحد يعني الـ\nsecond series هي مكانه\nالخلاصة كل period بيملا الـ d sublevel\nاللي رقمه أقل بواحد\nمن الأربعة دول الباب كله بيركز على الـ\nfirst series يلا نقرّب\nالعشر elements دول مين بالظبط تقدروا\nتعدّوهم بالترتيب من غير غلطة\nافتكروا الـ short form الـ noble gas اللي\nقبل العنصر بين قوسين والباقي بعده\nزي الـ scandium argon four s two three d\none أول واحد في الصف\nولحد الـ zinc argon four s two three d ten\nكده اتملت عالآخر\nيلا نعدّهم بالترتيب scandium titanium\nvanadium دول التلاتة الأولانيين\nوبعدهم chromium manganese iron وده نجم\nالباب كله\nوفي الآخر cobalt nickel copper zinc عشرة\nبالظبط\nوكل واحد في column الـ scandium في group\nتلاتة والـ zinc في group اتناشر\nسؤال سريع الـ cobalt ولا الـ nickel مين\nالأول\nخلّوا بالكم الـ chromium قبل الـ manganese\nوالـ cobalt قبل الـ nickel مش العكس\nفي الـ earth's crust الـ iron لوحده خمسة\nفي المية\nأما الـ scandium والـ cobalt فدول من\nأندرهم خالص\nوالعشرة كلهم مع بعض تقريبًا سبعة في المية\nبس\nناس كتير فاكرة إن العنصر المهم هو اللي\nموجود بكميات كبيرة غلط\nالكتاب بيقول إن ليهم economic importance\nعالية رغم إنهم قليلين\nأنهي عنصر الـ atomic number بتاعه خمسة\nوعشرين فكّروا\nالإجابة manganese اللي بعد الـ chromium\nأربعة وعشرين\nالـ first series من الـ scandium للـ zinc\nقليلين بس ليهم economic importance عالية\nكده الصورة كاملة يلا نربطها ببعض\nنلم الحلقة في النص بين الـ s-block والـ\np-block الـ d-block بعشر columns كاملين\nوأربع transition series من three d لحد six\nd صف ورا صف\nوالـ first series من الـ scandium للـ zinc\nهي بطلة الباب ده\nفمين اللي في النص الـ main transition\nelements اللي بيملوا الـ d sublevel\nبالترتيب\nوليه في النص عشان three d بتتملي بعد four\ns وقبل four p بالظبط\nأول سؤال الـ cerium في الصفين اللي تحت\nmain ولا inner فكّروا\nالإجابة عنصر inner transition عشان الـ\ncerium في الـ f-block مش الـ d-block خالص\nوقولوها في جملة ليه عدد الـ columns في الـ\nd-block عشرة\nعشان الـ d sublevel بياخد عشرة electrons\nبالكتير\nآخر سؤال الـ silver في period خمسة في أنهي\ntransition series وقّفوا ثانية وفكّروا\nفي الـ second series period خمسة يعني four\nd خمسة ناقص واحد\nالحلقة الجاية الـ economic importance\nبتاعة العشرة دول","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"series_id":"chem-s3-en.ch1#sessions","episode_no":1,"episode_count":9,"lessons":["chem-s3-en.lesson-pt.blocks","chem-s3-en.lesson-te.d-block-groups","chem-s3-en.lesson-te.first-series-elements","chem-s3-en.lesson-te.position-in-periodic-table","chem-s3-en.lesson-te.transition-series"]},{"id":"chem-s3-en.video-episode-te-uses","kind":"episode","version":3,"ord":115,"content_lang":"ar-EG","primary_concept_id":"te.uses-sc-ti","concepts":[{"concept_id":"te.uses-sc-ti","role":"primary"},{"concept_id":"te.chromium-oxide-layer","role":"secondary"},{"concept_id":"te.uses-cu-zn","role":"secondary"},{"concept_id":"te.uses-fe-co","role":"secondary"},{"concept_id":"te.uses-mn","role":"secondary"},{"concept_id":"te.uses-ni","role":"secondary"},{"concept_id":"te.uses-v-cr","role":"secondary"}],"title":"Economic importance of the first transition series","payload":{"title":"Economic importance of the first transition series","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"16:9","format":"episode","script":[{"id":"c1","visual":"[CORE] COLD OPEN · FB. Frame 0 complete (L7): YK.icon 'implant' (cyan, 260) already at x 420, y 560 at t=0, label 'dental implant' (Cairo 800 40) under it + tag 'titanium' (gold, 40) on cue 'titanium'; YK.icon 'rail' (steel, 260) at x 960 on cue 'قطر' + 'railway track'; YK.icon 'can' (260) at x 1500 on cue 'كانز' + 'soft drink can'. Left → right in spoken order; 2% drift. Book pp.5-6.","tts_text":"سنّة titanium في بُق حد، قضيب قطر، وعلبة كانز في إيدك.","screen_text":"Dental implant · railway track · soft drink can"},{"id":"c2","visual":"[CORE] FB. Icons shrink to a row at y 260. YK.dBlockZoom strip at p 1 (stripW 1555, names 1, same tiles as video-episode-te-position Part 4; NOT 10 elementCards) slides in at y 620 on line start; headline 'Sc → Zn: ten elements' (Cairo 1000 64, x 96, y 940) on cue 'العشرة'. From cue 'عنصر' gold dashed YK.arrow from each icon to its tile (stagger 0.3 s): implant → Ti, rail → Mn, can → Mn.","tts_text":"ورا كل واحدة فيهم عنصر من العشرة اللي عرفناهم.","screen_text":"Sc → Zn: ten elements"},{"id":"c3","visual":"[CORE] FB (match cut): the 10 tiles collapse into one violet slice. Crust bar x 96–1824, y 560, h 140 (steelDark), label \"earth's crust\" (Cairo 800 44) on cue 'earth'; the violet slice grows to 7% of the bar width (121 px) from the left on cue 'سبعة' + YK.label '7%' (mono 72, gold) above it. Headline 'Nearly 7% of the weight of earth's crust' (Cairo 1000 64, x 96, y 300). Book p.5.","tts_text":"كلهم سوا حوالي سبعة في المية بس من وزن الـ earth's crust كله.","screen_text":"Nearly 7% of the weight of earth's crust"},{"id":"c4","style":"curious","visual":"[CORE] BIG QUESTION · FB. Crust bar dims to 40%; question 'Only 7%. Why such high economic importance?' (Cairo 1000 84, x 96, y 760, maxWidth 1728) on line start; 'economic importance' pulses gold on cue 'economic'. 1 s pause: 2% push-in. Book p.5.","tts_text":"طب إزاي حاجة قليلة كده، يبقى ليها economic importance عالية؟","screen_text":"Only 7%. Why such high economic importance?","pause_after_s":1},{"id":"t1","visual":"[CORE] TITLE CARD (≤ 4 s from line start, out by min(start+4, cueEnd)). YK.titleCard({title:'Economic importance of the first transition series', chip:'Unit 2', subtitle:'Chapter 1: Transition Elements'}) Cairo 1000 ≤ 120, 2 lines; parts row under it (Cairo 800 32, two rows): '1 Scandium & titanium · 2 Vanadium · 3 Chromium · 4 Chromium oxide layer · 5 Manganese' / '6 Iron · 7 Cobalt · 8 Nickel · 9 Copper & zinc'. Then camera move into the PART 1 card (in this line's 2.5 s pause).","tts_text":"حلقتنا: الـ economic importance بتاعة الـ transition series الأولى، عنصر عنصر.","screen_text":"Economic importance of the first transition series","pause_after_s":2.5},{"id":"s1l1","visual":"PART 1/9 · te.uses-sc-ti · objective: Explain the uses of scandium and titanium and their reasons · [CORE] Segment card in t1's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 1 OF 9', title:'Economic importance of scandium and titanium'}) + objective line (Cairo 600 40) under it; the card collapses into YK.chip(ctx, 96, 64, 'Economic importance of scandium and titanium', {kind:'segment', align:'left'}), on until the segment's micro-recap. Line · TP: YK.elementCard({Z:21, config:''}) (w 300) in the text panel + 'a very small amount, spread on a large area' (Cairo 800 40) on cue 'قليل'. Stage: crust cross-section (3 custom strata bands) with ~40 tiny violet specks (YK.rng seed 21) spreading wide on cue 'مفرّق'; '?' (Cairo 1000 96, gold) on cue 'فايدته'. Book p.5.","tts_text":"أول واحد، الـ scandium، قليل جدًا ومفرّق في الأرض. فايدته إيه؟","screen_text":"₂₁Sc: a very small amount, spread on a large area"},{"id":"s1l2","visual":"[CORE] New term 1 'alloy'. TP. Visual order = word order: on cue 'scandium' 3 violet Sc discs (YK.atomDisc el 'Sc') appear above the stage; on cue 'aluminium' YK.lattice (rows 4, cols 7, color C.steel) slides in and the 3 Sc drop into sites (substitute:[{r:1,c:2},{r:2,c:5},{r:3,c:1}], colors.substitute = YK.atomColor('Sc')) = the episode's ALLOY MODEL (reused in Parts 2, 8, 9). On cue 'alloy' tag 'alloy' (Cairo 800 44, gold); badges 'light' on cue 'خفيف', 'very hard' on cue 'جامد'. Text panel: screen_text in 2 rows (Cairo 1000 56). Book p.5.","tts_text":"شوية scandium صغيرين على الـ aluminium بيدّوا alloy خفيف وجامد جدًا.","screen_text":"A little scandium + aluminum → light, very hard alloy"},{"id":"s1l3","visual":"[CORE] The one definition card of Part 1 (E3a): YK.termCard({term:'Alloy', def:'A metal mixed with other elements', keys:['mixed']}) in the text panel on cue 'alloy'. NO 'More in Unit 7' line (unlabelled forward reference; see tts fix). Stage: 1.0 s camera push into the lattice, the 3 Sc sites glow.","tts_text":"والـ alloy يعني metal متخلط بعناصر تانية.","screen_text":"Alloy: a metal mixed with other elements"},{"id":"s1l4","visual":"[CORE] FB. The lattice shrinks and morphs into YK.icon 'plane' (steel, 520) on line start; label 'MiG fighter jets' (Cairo 800 48) on cue 'MiG' + small tag 'Sc–Al alloy' (40). Book p.5.","tts_text":"والـ alloy ده لطيارات الـ MiG الحربية.","screen_text":"Sc–Al alloy → MiG fighter jets"},{"id":"s1l5","visual":"[TRIM] TP. Stage: YK.icon 'lamp' (360) + label 'mercury vapour lamp' on cue 'mercury'; a 3-disc Sc pinch drops in on cue 'بيدّي'; YK.glowCircle around the lamp tweens cool-white → warm sunlight on cue 'الشمس' + label 'light like sunlight'. Text panel: 'TV photography at night' (Cairo 800 44) on cue 'للتصوير' (no camera icon in the kit: text only). Book p.5.","tts_text":"وفي لمبات الـ mercury vapour، بيدّي نور شبه الشمس للتصوير بالليل.","screen_text":"Mercury vapour lamps: light like sunlight → TV photography at night"},{"id":"s1l6","visual":"[CORE] SS (E7, first-mentioned left): left panel 'Titanium' (cue 'titanium'), right 'Steel' (cue 'steel'), same scale; two equal 'rigid' bars (same height = rigidity); under each a small 'density' bar on cue 'density': Ti shorter, gap in gold + label 'less dense'. No numbers. Book p.5.","tts_text":"تاني عنصر، الـ titanium: جامد زي الـ steel، بس الـ density بتاعته أقل.","screen_text":"Titanium: rigid as steel, but less dense"},{"id":"s1l7","visual":"[CORE] FB. YK.icon 'plane' (left) on cue 'الطيارات' + space shuttle (custom 3-path silhouette in the lab.js line style; kit wish: 'shuttle' icon) on cue 'الفضاء'; tag 'Ti–Al alloys' (Cairo 800 48) on cue 'alloys'; labels 'aircraft' / 'space shuttle'. Book p.5.","tts_text":"فالـ alloys بتاعته مع الـ aluminium بتدخل في الطيارات وسفن الفضاء.","screen_text":"Ti–Al alloys: aircraft and space shuttle"},{"id":"s1l8","visual":"[CORE] New term 2 'durability'. SS (first-mentioned left): left 'Aluminium', right 'Titanium' bars; a shared custom heat bar (heatRed) rises from line start (HEAT GAUGE model, reused in Part 8). On cue 'بيلين' the Al bar bends (coral) + 'hardness decreases'; on cue 'durability' the Ti bar stays straight + 'maintains its durability' (gold). Book p.5.","tts_text":"ليه؟ في الحرارة العالية الـ aluminium بيلين، والـ titanium الـ durability بتاعته ثابتة.","screen_text":"High temperature: Ti maintains its durability; Al hardness decreases"},{"id":"s1l9","visual":"[CORE] Misconception (te.uses-sc-ti #1) · TP. Stage: YK.icon 'implant' (420, cyan) on cue 'implants' + a custom ball-and-socket joint on cue 'والمفاصل'; text panel coral 'because it is hard?' (Cairo 800 44) on cue 'جامد', YK.wrongMark on cue 'غلط'; the wrong text exits < 2 s.","tts_text":"وفي implants السنان والمفاصل الصناعية؟ ناس كتير فاكرة إنه عشان جامد… غلط.","screen_text":"Dental implants · artificial joints: because it is hard? ✕"},{"id":"s1l10","visual":"[CORE] New term 3 'inert'. TP (no 2nd definition card in Part 1): 'Inert' (Cairo 1000 72, mint) on cue 'inert' + 'the body does not eject it, no poisoning' (Cairo 600 40) on cue 'مبيرفضوش'; YK.rightMark. Stage: the implant inside a jawbone (custom bone-tone block), calm cell dots around it, no reaction sparks. Book p.5.","tts_text":"السبب إنه inert، مبيتفاعلش، فالجسم مبيرفضوش ومفيش تسمم.","screen_text":"Inert: the body does not eject it, no poisoning ✓"},{"id":"s1l11","visual":"PREREQ phys.em-spectrum [RECAP-PREREQ] TP, ≤ 8 s. YK.chip(ctx, 96, 140, 'Electromagnetic radiation (UV, X-rays, gamma)', {kind:'prereq'}) under the segment chip. Stage: the short's 7-band spectrum ladder (same order, colours and labels), only the 'Ultraviolet (UV)' band lit violet on cue 'ultraviolet'; the short's forearm silhouette reddens on cue 'بتأذي'. Reference only.","tts_text":"فاكرين الـ ultraviolet؟ أشعة مش بنشوفها، بس بتأذي الجلد.","screen_text":"Ultraviolet (UV): invisible rays that harm the skin"},{"id":"s1l12","visual":"[CORE] Refutes misconception #3 (TiO₂, not Ti metal) · FB. Skin band across the bottom (y 820–960); YK.icon 'sunscreen' (300) at x 400 + YK.label 'TiO_2' (mono 64) on cue 'dioxide'; small coral 'Ti metal' + YK.wrongMark on cue 'مش' (< 1 s); a layer of tiny white TiO₂ dots spreads on the skin; violet UV wavy rays from the top right hit the layer and stop on cue 'يمنع'; label 'nanoparticles prevent the effect of UV' (Cairo 800 40). Book p.5.","tts_text":"والـ titanium dioxide، مش الـ metal، في كريمات الشمس، يمنع الـ ultraviolet عنّا.","screen_text":"Titanium dioxide (TiO₂): sun protection cosmetics, prevents the effect of UV"},{"id":"s1l13","visual":"[CORE] PAUSE-AND-PREDICT (new case: short = artificial joints, lesson = bone plate) · TP. YK.checkPause in the text panel (question 'A racing bike frame: rigid as steel, but lighter. Which metal?', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: custom bike frame outline (2 triangles + 2 wheels) with badges 'rigid' and 'light'.","tts_text":"طب frame عجلة سباق، جامد زي الـ steel وأخف. تختاروا إيه؟ وقّفوا وفكّروا. <long pause>","screen_text":"A racing bike frame: rigid as steel, but lighter. Which metal?","pause_after_s":2},{"id":"s1l14","visual":"[CORE] Answer · TP: YK.elementCard({Z:22, config:''}) snaps onto the frame on cue 'titanium' + YK.rightMark; reason 'rigid as steel, less dense' (Cairo 800 40) on cue 'density'.","tts_text":"الـ titanium، جامد زي الـ steel، والـ density بتاعته أقل.","screen_text":"Titanium: rigid as steel, less dense ✓"},{"id":"s1l15","visual":"[CORE] MICRO-RECAP · TP: YK.takeaway({title:'Economic Importance of Scandium and Titanium', line:'Sc: hardens aluminium · Ti: inert, durable at high temperatures', t, pulse:[{word:'inert', at:YK.cue('s1l15','inert')}, {word:'durable', at:YK.cue('s1l15','durable')}]}); stage: the plane + implant icons small.","tts_text":"الخلاصة: الـ scandium بيقوّي الـ aluminium، والـ titanium inert و durable في الحرارة.","screen_text":"Sc: hardens aluminum · Ti: inert, durable at high temperatures"},{"id":"s1l16","visual":"[CORE] SO-WHAT · FB. Al lattice slides out left; YK.icon 'spring' (steel blue, 420) slides in on cue 'steel'; segment chip out; camera move 1.2 s into the PART 2 card (this line's 2.5 s pause).","tts_text":"الاتنين قوّوا الـ aluminium… طب الـ steel مين بيقوّيه؟","screen_text":"Next: the steel of car springs","pause_after_s":2.5},{"id":"s2l1","visual":"PART 2/9 · te.uses-v-cr · objective: Describe the uses of vanadium and vanadium pentoxide · [CORE] Segment card in s1l16's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 2 OF 9', title:'Economic importance of vanadium and chromium'}) + objective line (Cairo 600 40) under it; the card collapses into YK.chip(ctx, 96, 64, 'Economic importance of vanadium and chromium', {kind:'segment', align:'left'}), on until the segment's micro-recap. Line · FB: a car wheel (custom) on a bumpy road; YK.icon 'spring' compresses in a loop (scaleY sine, ≤ 1 s period); label 'squeezed thousands of times' on cue 'آلاف'.","tts_text":"سوست العربية بتتضغط آلاف المرات… ليه مبتتكسرش؟","screen_text":"Car springs: squeezed thousands of times"},{"id":"s2l2","visual":"[CORE] TP. ALLOY MODEL (Part 1), word order: 3 V discs (YK.atomDisc el 'V') appear on cue 'vanadium'; the steel lattice (color C.steel) slides in on cue 'steel' and the V discs drop into sites. Text panel 'Steel + a small portion of vanadium' (Cairo 1000 56). Book p.6.","tts_text":"السر: نسبة صغيرة من الـ vanadium بتتحط على الـ steel نفسه.","screen_text":"Steel + a small portion of vanadium"},{"id":"s2l3","visual":"[CORE] TP. The lattice morphs into YK.icon 'spring' tagged 'alloy' on cue 'alloy'; badges 'high hardness' on cue 'جامد', 'resists corrosion' on cue 'corrosion'; custom cyan water drops slide off. Text panel: screen_text (Cairo 800 44). Book p.6.","tts_text":"فيطلع alloy جامد جدًا، وبيقاوم الـ corrosion، يعني التآكل.","screen_text":"High hardness alloy, resists corrosion → car springs"},{"id":"s2l4","visual":"PREREQ chem.catalyst [RECAP-PREREQ] FB, ≤ 8 s. YK.chip prereq 'Catalyst' (96, 140). The short's model: YK.balance (level, value 0) with a black powder heap (custom) labelled 'before' / 'after' on each pan, 'same mass' (gold) on cue 'زي'; label 'catalyst' on cue 'catalyst'. Reference only.","tts_text":"فاكرين الـ catalyst؟ بيسرّع التفاعل، وبيفضل زي ما هو.","screen_text":"Catalyst: speeds up a reaction without being used up"},{"id":"s2l5","visual":"[CORE] TP. Text panel: YK.formula 'V2O5' (mono 96) builds on cue 'pentoxide' + 'vanadium pentoxide' (Cairo 800 40). Stage: CATALYST-OVER-ARROW MODEL (reused in Parts 6 and 8): YK.formula 'reactants ->[V2O5] products' (mono 56), 'V₂O₅' drops onto the arrow + label 'catalyst' (gold) on cue 'catalyst'. Book p.6.","tts_text":"وأهم مركّب للـ vanadium هو الـ vanadium pentoxide، وده catalyst مهم.","screen_text":"Vanadium pentoxide V₂O₅: a catalyst"},{"id":"s2l6","visual":"[CORE] TP. Stage: custom ceramic vase + glass pane, both take a tint (no colour named, G37) on cue 'dyes'; labels 'dyes' (gold), 'ceramics and glass industry'. Text panel keeps 'V₂O₅'. Book p.6.","tts_text":"وكمان بيدخل dyes في صناعة السيراميك والإزاز.","screen_text":"V₂O₅: dyes in ceramics and glass industry"},{"id":"s2l7","visual":"[TRIM] New term 'magnetic conductors' · FB. YK.magnet({type:'bar', size:520, field: prog from cue 'magnetic', t}) + label 'strong magnetic conductors' (book wording, Cairo 800 48) on cue 'magnetic'; small 'V₂O₅' tag. Book p.6.","tts_text":"وبيدخل كمان في صناعة magnetic conductors قوية.","screen_text":"V₂O₅: manufacture of strong magnetic conductors"},{"id":"s2l8","visual":"[CORE] Misconception (te.uses-v-cr #1) · TP: coral 'Only a dye' + YK.wrongMark on cue 'لأ' (< 2 s), then the s2l5 catalyst-over-arrow returns + YK.rightMark on cue 'catalyst', 'Also a catalyst' (mint).","tts_text":"ناس كتير فاكرة إنه dye وبس… لأ، ده catalyst كمان.","screen_text":"Only a dye ✕ · Also a catalyst ✓"},{"id":"s2l9","visual":"[CORE] PAUSE-AND-PREDICT (new case; replaces v1's 'how much is left', which re-asked the catalyst prereq just shown in s2l4) · TP. YK.checkPause in the text panel (question 'A glass factory and a chemical plant both buy V₂O₅. What for?', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: custom glass pane (left) + YK.icon 'factory' (right), a YK.icon 'flask' labelled 'V₂O₅' between them.","tts_text":"مصنع إزاز ومصنع كيماويات، الاتنين بيشتروا vanadium pentoxide. كل واحد عايزه ليه؟ وقّفوا وفكّروا. <long pause>","screen_text":"A glass factory and a chemical plant both buy V₂O₅. What for?","pause_after_s":2},{"id":"s2l10","visual":"[CORE] Answer · SS: left 'Glass factory': pane tints + 'dyes' + YK.rightMark on cue 'dyes'; right 'Chemical plant': catalyst-over-arrow with V₂O₅ + 'catalyst' + YK.rightMark on cue 'catalyst'; small 'not only a dye' (gold) on cue 'وبس'.","tts_text":"الإزاز عشان الـ dyes، والمصنع التاني عشان catalyst. مش dye وبس.","screen_text":"Glass: dyes ✓ · Chemical plant: catalyst ✓"},{"id":"s2l11","visual":"[CORE] MICRO-RECAP · TP: YK.takeaway({title:'Economic Importance of Vanadium and Chromium', line:'V: hardens steel (car springs) · V₂O₅: catalyst, dyes', formula:'V2O5', t, pulse:[{word:'catalyst', at:YK.cue('s2l11','catalyst')}]}); stage: spring icon.","tts_text":"الخلاصة: الـ vanadium بيقوّي الـ steel، والـ vanadium pentoxide بيتستخدم catalyst و dyes كمان.","screen_text":"V: hardens steel (car springs) · V₂O₅: catalyst, dyes"},{"id":"s2l12","visual":"[CORE] SO-WHAT · FB: the dBlockZoom strip (c2 model) returns; highlight V → Cr on cue 'chromium'; segment chip stays (same title); camera move into the PART 3 card (2.5 s pause).","tts_text":"وجاره على طول، الـ chromium… استخداماته إيه؟","screen_text":"Next: chromium","pause_after_s":2.5},{"id":"s3l1","visual":"PART 3/9 · te.uses-v-cr · objective: State the uses of chromium and two of its compounds · [CORE] Segment card in s2l12's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 3 OF 9', title:'Economic importance of vanadium and chromium'}) + objective line (Cairo 600 40) under it; the card collapses into YK.chip(ctx, 96, 64, 'Economic importance of vanadium and chromium', {kind:'segment', align:'left'}), on until the segment's micro-recap. Line · SS: custom shiny tap (left) on cue 'الحنفية' with a gloss sweep, custom leather shoe (right) on cue 'الجزمة'; '?' on cue 'إزاي'. (Kit wish: 'tap', 'shoe' icons.)","tts_text":"الحنفية اللي بتلمع، والجزمة الجلد… الاتنين فيهم chromium. إزاي؟","screen_text":"A shiny tap and leather shoes: chromium?"},{"id":"s3l2","visual":"[CORE] New term 1 'metal plating' · FB: a large dull grey tap; a chrome coat sweeps over it left → right (linear sheen gradient) on cue 'plating'; label 'metal plating' (Cairo 800 48). PLATING MODEL (reused in Part 8). Book p.6.","tts_text":"الـ chromium بيستخدموه في الـ metal plating، يعني يغلّفوا بيه metals تانية.","screen_text":"Chromium: metal plating"},{"id":"s3l3","visual":"[CORE] New term 2 'leather tanning' · TP: custom raw hide (beige, ragged) tweens into finished leather (smooth, brown) on cue 'tanning'; label 'leather tanning'. Text panel 'Chromium: leather tanning'. Book p.6.","tts_text":"وكمان بيستخدموه في الـ leather tanning، يعني دبغ الجلود.","screen_text":"Chromium: leather tanning"},{"id":"s3l4","visual":"[CORE] TP. Text panel: 'Chromium III oxide' (Cairo 800 44) on cue 'oxide' + YK.formula 'Cr_{!{2}}O_{!{3}}' (mono 96): '2' highlights on cue 'اتنين', '3' on cue 'وتلاتة'. Stage: YK.icon 'flask' labelled 'Cr₂O₃' + a custom paint stroke labelled 'dyes' on cue 'dyes'. Book p.6.","tts_text":"ومن مركّباته chromium تلاتة oxide، فيه اتنين chromium وتلاتة oxygen، للـ dyes كمان.","screen_text":"Chromium III oxide Cr₂O₃: manufacture of dyes"},{"id":"s3l5","visual":"PREREQ redox.basic [RECAP-PREREQ] FB, ≤ 8 s. YK.chip prereq 'Oxidation and reduction by oxygen' (96, 140). The short's model: YK.formula 'CuO + H2 -> Cu + H2O' (mono 80) centred; the O tile moves from CuO to H₂ on cue 'oxygen'; tag 'oxidizing agent' (gold) under CuO on cue 'oxidizing'. Reference only.","tts_text":"فاكرين الـ oxidizing agent؟ بيدّي oxygen لغيره فيأكسده.","screen_text":"Oxidizing agent: supplies oxygen to another substance"},{"id":"s3l6","visual":"[CORE] TP. Text panel: YK.formula 'K2Cr2O7' (mono 88) builds on cue 'dichromate' + 'potassium dichromate' (40). Stage: YK.icon 'flask' 'K₂Cr₂O₇'; an O disc (YK.atomDisc el 'O') leaves it and joins a grey particle labelled 'another substance' on cue 'oxidizing' (same O-passing move as s3l5); tag 'oxidizing agent' (gold). Book p.6.","tts_text":"والمركّب التاني، الـ potassium dichromate، مش reducing agent… ده oxidizing agent، بيأكسد غيره.","screen_text":"Potassium dichromate K₂Cr₂O₇: oxidizing agent"},{"id":"s3l7","visual":"[CORE] PAUSE-AND-PREDICT (new case; targets the K₂Cr₂O₇ role) · TP. YK.checkPause in the text panel (question 'A paint factory needs a chromium compound for dyes. Which one?', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: two flasks 'Cr₂O₃' (left) | 'K₂Cr₂O₇' (right), no use tags.","tts_text":"طب مصنع بويات محتاج مركّب chromium للـ dyes. ياخد أنهي واحد؟ وقّفوا وفكّروا. <long pause>","screen_text":"A paint factory needs a chromium compound for dyes. Which one?","pause_after_s":2},{"id":"s3l8","visual":"[CORE] Answer · SS: left Cr₂O₃ flask + YK.rightMark + paint stroke on cue 'chromium'; right K₂Cr₂O₇ gets its 'oxidizing agent' tag on cue 'oxidizing' (no ✕ on the compound).","tts_text":"الـ chromium تلاتة oxide. أما الـ potassium dichromate، فشغلته oxidizing agent، مش dye خالص.","screen_text":"Cr₂O₃: dyes ✓ · K₂Cr₂O₇: oxidizing agent"},{"id":"s3l9","visual":"[CORE] MICRO-RECAP · TP: YK.takeaway({title:'Economic Importance of Vanadium and Chromium', line:'Cr: plating, tanning · Cr₂O₃: dyes', formula:'Cr2O3', t, pulse:[{word:'plating', at:YK.cue('s3l9','plating')}, {word:'tanning', at:YK.cue('s3l9','tanning')}]}).","tts_text":"الخلاصة: الـ chromium للـ plating والـ tanning، وأكسيده للـ dyes كمان.","screen_text":"Cr: plating, tanning · Cr₂O₃: dyes"},{"id":"s3l10","visual":"[CORE] SO-WHAT · FB: the shiny tap shrinks to a small icon top-right (x ≤ 1824); segment chip out; camera pulls back into the recap map (no fade).","tts_text":"قبل ما نشوف سر لمعة الـ chromium، نلم اللي فات بسرعة.","screen_text":"Before the secret of chromium: what we have so far"},{"id":"m1l1","visual":"[CORE] MID-EPISODE RECAP 1 · FB. YK.flow({layout:'row', area:{x:96, y:420, w:1728, h:280}, node:{size:40}, nodes 1-4, edges left → right}); node 1 'Sc: light, hard alloy' lit on cue 'scandium', YK.icon 'plane' (120) under it.","tts_text":"الـ scandium بيدّي الـ aluminium alloy خفيف وجامد.","screen_text":"Sc: light, hard alloy"},{"id":"m1l2","visual":"[CORE] Node 2 'Ti: inert, durable' + edge on cue 'titanium'; YK.icon 'implant' under it.","tts_text":"والـ titanium inert في الجسم، و durable في الحرارة.","screen_text":"Ti: inert, durable"},{"id":"m1l3","visual":"[CORE] Node 3 'V: hard steel' (sub 'V₂O₅: catalyst') + edge on cue 'vanadium'; YK.icon 'spring'.","tts_text":"والـ vanadium بيقوّي الـ steel، والـ vanadium pentoxide بيبقى catalyst مهم.","screen_text":"V: hard steel · V₂O₅: catalyst"},{"id":"m1l4","visual":"[CORE] Node 4 'Cr: plating, tanning' + edge on cue 'chromium'; the small tap icon pulses gold (sets up Part 4). Camera move into the PART 4 card (2.5 s pause).","tts_text":"والـ chromium بيدخل في الـ plating والـ tanning كمان.","screen_text":"Cr: plating, tanning","pause_after_s":2.5},{"id":"s4l1","visual":"PART 4/9 · te.chromium-oxide-layer · objective: Explain why chromium resists the effect of the atmospheric air · [CORE] Segment card in m1l4's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 4 OF 9', title:'Why chromium resists the effect of atmosphere'}) + objective line (Cairo 600 40) under it; the card collapses into YK.chip(ctx, 96, 64, 'Why chromium resists the effect of atmosphere', {kind:'segment', align:'left'}), on until the segment's micro-recap. Line [re-hook; v1 s4l2 moved up] · FB: custom chrome tap, timelapse counter 'year 1 → 10' (YK.label mono 48) from line start, the tap stays shiny (sheen sweep every 2 s); '?' (gold) on cue 'إزاي'. Book p.6.","tts_text":"حنفية الـ chromium بتفضل تلمع سنين في الهوا. إزاي؟","screen_text":"Chromium resists the effect of the atmospheric air. How?"},{"id":"s4l2","visual":"[CORE] (v1 s4l1) TP: text panel 'Chromium' + 'chemically active' (Cairo 1000 64, gold) on cue 'chemically'; stage: a row of 6 Cr discs (YK.atomDisc el 'Cr') flashes a reactive glow on cue 'بيتفاعل'. Book p.6.","tts_text":"الكتاب بيقول على الـ chromium إنه chemically active، يعني بيتفاعل بسهولة.","screen_text":"Chromium: chemically active"},{"id":"s4l3","visual":"[CORE] Misconception (te.chromium-oxide-layer #1) · TP: 'Unreactive' (coral, Cairo 800 48) + YK.wrongMark on cue 'غلط', exits < 2 s.","tts_text":"ناس كتير فاكرة إنه مبيتفاعلش أصلًا… غلط.","screen_text":"Unreactive ✕"},{"id":"s4l4","visual":"[CORE] FB. OXIDE-SKIN MODEL (same as video-short-te.chromium-oxide-layer): YK.oxideSkin(ctx, 160, 260, 1600, 700, {metal:'Cr', porous:false, p: prog(cue 'oxygen' → cue 'سطحه' + 0.6), label:'metal oxide', t}); O₂ molecules (YK.molecule 'O2') fall onto the surface on cue 'oxygen'; YK.rightMark on cue 'سطحه'.","tts_text":"هو بيتفاعل مع الـ oxygen، ويتكوّن metal oxide على سطحه.","screen_text":"Reacts with oxygen of air → metal oxide on its surface ✓"},{"id":"s4l5","visual":"[CORE] New term 1 'molecular volume' · FB (same shot, build): 1.0 s camera push onto 3 bricks; gold brackets compare one oxide brick (w/12) with one Cr disc under it, '>' (gold) on cue 'أكبر'; label 'molecular volume of the oxide > that of the metal atoms' (Cairo 800 40) on cue 'molecular'. Book p.6.","tts_text":"والـ molecular volume بتاع الـ oxide أكبر من الـ metal atoms نفسها.","screen_text":"Molecular volume of the oxide > that of the metal atoms"},{"id":"s4l6","visual":"[CORE] New term 2 'non-porous' · FB: camera back; the layer is continuous (porous:false, p 1), seams glow once; label 'non-porous layer' (gold, 48) on cue 'non'.","tts_text":"فالطبقة بتقفل كل الفراغات، وتبقى non-porous، مفيهاش مسام.","screen_text":"A non-porous layer"},{"id":"s4l7","visual":"[CORE] FB: oxideSkin acid option reused as oxygen: acid 1, particleColor YK.C.atomO, acidLabel 'O₂'; particles bounce off the layer, atoms below stay bright; label 'prevents the continued interaction with oxygen of air' (40) on cue 'مبيوصلش'. Book p.6.","tts_text":"فالـ oxygen مبيوصلش للـ metal تاني، والتفاعل بيقف عند السطح.","screen_text":"Prevents the continued interaction with oxygen of air"},{"id":"s4l8","visual":"[CORE] PAUSE-AND-PREDICT (v1 s4l9; new case: short and lesson used aluminium; targets misconception #2) · TP. YK.checkPause in the text panel (question 'A metal's oxide has a smaller volume than its atoms. Protected?', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: a row of grey metal discs + ONE small oxide brick beside one disc, gold '<' bracket (the given only; no layer drawn, so the answer is not on screen).","tts_text":"طب metal الـ oxide بتاعه volume أصغر من الـ atoms. هيتحمي؟ وقّفوا وفكّروا. <long pause>","screen_text":"A metal's oxide has a smaller volume than its atoms. Protected?","pause_after_s":2},{"id":"s4l9","visual":"[CORE] Answer (v1 s4l10) · FB: YK.oxideSkin({metal:'M' (generic: no symbol drawn), layerColor C.steelDark, porous:true, p:1, acid: prog from cue 'يعدّي', particleColor YK.C.atomO, t}): particles pass the gaps and the atoms below pit; YK.rightMark; 'porous layer: the reaction continues' (Cairo 800 44) on cue 'porous'.","tts_text":"لأ، الطبقة هتبقى porous، فالـ oxygen يعدّي والتفاعل يكمّل.","screen_text":"No: a porous layer, the reaction continues ✓"},{"id":"s4l10","visual":"PREREQ chem.rusting-corrosion [RECAP-PREREQ] (v6: compares the result only, not the cause: rust is porous, so rusting continues; v1 s4l8 moved after the predict so it no longer shows the answer first) · SS, ≤ 8 s. YK.chip prereq 'Rusting and corrosion'. Left 'Chromium': oxideSkin porous:false, O bouncing off; right 'Iron': oxideSkin({metal:'Fe', porous:true, layerColor:'#8B3A1A', label:'rust'}) exactly as video-short-chem.rusting-corrosion l5, particles pass through on cue 'porous'. Same scale.","tts_text":"نفس النتيجة في الـ rust على الـ iron: طبقته porous، فالـ rusting بيكمّل.","screen_text":"Rust on iron: porous too → rusting continues"},{"id":"s4l11","visual":"[CORE] MICRO-RECAP · TP: YK.takeaway({title:'Why Chromium Resists the Effect of Atmosphere', line:'Larger oxide volume → non-porous layer → protection', t, pulse:[{word:'non-porous', at:YK.cue('s4l11','non')}]}); stage: the Cr oxide skin, O bouncing.","tts_text":"يعني الـ oxide أكبر volume، فالطبقة non-porous، والـ chromium محمي.","screen_text":"Larger oxide volume → non-porous layer → protection"},{"id":"s4l12","visual":"[CORE] SO-WHAT · FB: dBlockZoom strip, highlight Cr → Mn on cue 'manganese'; segment chip out; camera move into the PART 5 card (2.5 s pause).","tts_text":"طب جاره الـ manganese، حكايته إيه؟","screen_text":"Next: manganese","pause_after_s":2.5},{"id":"s5l1","visual":"PART 5/9 · te.uses-mn · objective: State the uses of manganese, its alloys and its compounds · [CORE] Segment card in s4l12's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 5 OF 9', title:'Economic importance of manganese'}) + objective line (Cairo 600 40) under it; the card collapses into YK.chip(ctx, 96, 64, 'Economic importance of manganese', {kind:'segment', align:'left'}), on until the segment's micro-recap. Line · FB: YK.icon 'rail' + 'can' (cold-open icons) with 'Mn' tags; a custom grey bar 'pure Mn' centre on cue 'manganese', '?' on cue 'ليه'.","tts_text":"الـ manganese عمره ما بيتستخدم لوحده. ليه؟","screen_text":"Manganese: never used as a pure metal. Why?"},{"id":"s5l2","visual":"[CORE] New term 1 'brittle'. Misconception (te.uses-mn #1) · TP: coral 'Used pure' + YK.wrongMark on cue 'لأ'; YK.hammer strikes the bar and it shatters into 5 shards (YK.rng seed 25) on cue 'بيتكسر'; 'brittle' (gold, 56) on cue 'brittle'. Book p.6.","tts_text":"ناس فاكرة إنه بيتستخدم pure… لأ، ده brittle، بيتكسر لو اتخبط.","screen_text":"Used pure ✕ · Brittle ✓"},{"id":"s5l3","visual":"[CORE] TP: text panel YK.list 'alloys' (cue 'alloys') / 'compounds' (cue 'compounds'), Cairo 1000 64; stage: the shards regroup into two labelled trays. Book p.6.","tts_text":"فبيدخل دايمًا في alloys أو compounds بس.","screen_text":"Always used as alloys or compounds"},{"id":"s5l4","visual":"[CORE] New term 2 'ferromanganese' · FB: YK.icon 'rail' (620) along the bottom; two custom bars on one baseline: 'steel' (C.steel) and 'ferromanganese' (taller, gold) grow on cue 'أجمد'; label 'ferromanganese' on cue 'ferromanganese', 'harder than steel'. No numbers. Book p.6.","tts_text":"الـ ferromanganese أجمد من الـ steel، فبيعملوا منه الـ railway track بتاع القطر.","screen_text":"Ferromanganese alloy: harder than steel → railway track"},{"id":"s5l5","visual":"[CORE] TP: YK.icon 'can' (420), drops slide off; labels 'aluminium–manganese alloy' on cue 'alloy', 'resists corrosion' on cue 'corrosion'. Book p.6.","tts_text":"ومع الـ aluminium بيعمل alloy بيقاوم الـ corrosion، للكانز.","screen_text":"Aluminum–manganese alloy: soft drink cans (resists corrosion)"},{"id":"s5l6","visual":"[CORE] FB: dry-cell cutaway = YK.icon 'battery' (560) + an inner layer rect labelled 'MnO₂' glowing on cue 'manganese'; an O disc leaves the layer (O-passing move of Part 3) + 'strong oxidizing agent' (gold) on cue 'oxidizing'; label 'dry cell'. Book p.6.","tts_text":"وفي الـ dry cell، فيه manganese dioxide، oxidizing agent قوي.","screen_text":"Manganese dioxide MnO₂: strong oxidizing agent in dry cell"},{"id":"s5l7","visual":"[CORE] TP: YK.icon 'flask' labelled 'KMnO₄' (left of stage) + tag 'antiseptic' on cue 'antiseptic'. Book p.6.","tts_text":"والـ potassium permanganate بيستخدموه antiseptic، يعني مطهّر.","screen_text":"Potassium permanganate KMnO₄: antiseptic"},{"id":"s5l8","visual":"[CORE] TP: second YK.icon 'flask' 'MnSO₄' (right) + tag 'fungicide' on cue 'fungicide'; custom leaf whose spots fade on cue 'الفطريات'. Book p.6.","tts_text":"أما الـ manganese sulphate، فده fungicide، بيقتل الفطريات.","screen_text":"Manganese II sulphate MnSO₄: fungicide"},{"id":"s5l9","visual":"[CORE] PAUSE-AND-PREDICT (new case; targets the KMnO₄/MnSO₄ swap #2) · TP. YK.checkPause in the text panel (question 'A pharmacy sells a manganese compound as an antiseptic. Which one?', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: the two flasks, their use tags flipped face-down.","tts_text":"صيدلية بتبيع مركّب manganese بيستخدموه antiseptic… أنهي واحد؟ وقّفوا وفكّروا. <long pause>","screen_text":"A pharmacy sells a manganese compound as an antiseptic. Which one?","pause_after_s":2},{"id":"s5l10","visual":"[CORE] Answer · SS: left KMnO₄ + YK.rightMark + 'antiseptic' on cue 'permanganate'; right MnSO₄ tag 'fungicide' flips up on cue 'fungicide'.","tts_text":"الـ potassium permanganate، أما الـ sulphate فده fungicide للفطريات.","screen_text":"KMnO₄: antiseptic ✓ · MnSO₄: fungicide"},{"id":"s5l11","visual":"[CORE] MICRO-RECAP · TP: YK.takeaway({title:'Economic Importance of Manganese', line:'Mn: brittle → alloys and compounds only', t, pulse:[{word:'brittle', at:YK.cue('s5l11','brittle')}]}).","tts_text":"الخلاصة: الـ manganese brittle، فبيشتغل في alloys و compounds بس.","screen_text":"Mn: brittle → alloys and compounds only"},{"id":"s5l12","visual":"[CORE] SO-WHAT · FB: strip highlight Mn → Fe with a 0.6 s steel glint on cue 'iron'; segment chip out; camera move into the PART 6 card (2.5 s pause).","tts_text":"وبعده العنصر اللي الباب كله بيدور حواليه: الـ iron نفسه.","screen_text":"Next: iron","pause_after_s":2.5},{"id":"s6l1","visual":"PART 6/9 · te.uses-fe-co · objective: State the uses of iron and its role as a catalyst · [CORE] Segment card in s5l12's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 6 OF 9', title:'Economic importance of iron and cobalt'}) + objective line (Cairo 600 40) under it; the card collapses into YK.chip(ctx, 96, 64, 'Economic importance of iron and cobalt', {kind:'segment', align:'left'}), on until the segment's micro-recap. Line · FB montage left → right: YK.icon 'bridge' on cue 'الكوبري', YK.icon 'knife' (labelled 'surgical tools') on cue 'الجرّاح', custom fuel drop on cue 'fuel'; '?' on cue 'إزاي'.","tts_text":"من الكوبري لأدوات الجرّاح، كله iron… وكمان بيساعد نعمل fuel. إزاي؟","screen_text":"From bridges to surgical tools… and fuel?"},{"id":"s6l2","visual":"[CORE] FB uses row (labels under icons, not a text-panel list): 5 slots x 96–1824; on their cues: custom reinforced-concrete beam with rebar lines ('reinforced'), custom pylon ('الكهربا'), YK.icon 'knife' ('والسكاكين'), custom scalpel ('الجراحية'); labels Cairo 800 36. Slot 5 stays empty for s6l3. (Kit wish: 'pylon', 'concrete', 'scalpel' icons.) Book p.6.","tts_text":"الـ iron في الـ reinforced concrete، وأبراج الكهربا، والسكاكين، والأدوات الجراحية.","screen_text":"Reinforced concrete · electricity pylons · knives · surgical tools"},{"id":"s6l3","visual":"[CORE] FB: slot 5 of the s6l2 uses row: YK.icon 'pipe' on cue 'مواسير' + label 'gun and cannon pipes' (Cairo 800 36). Book p.6.","tts_text":"وكمان مواسير البنادق والمدافع، كلها من الـ iron برضه.","screen_text":"Gun and cannon pipes"},{"id":"s6l4","visual":"[CORE] TP: catalyst-over-arrow model (Part 2) with 'Fe' on the arrow ('reactants ->[Fe] products'), label 'catalyst' on cue 'catalyst'; text panel header 'Iron: a catalyst' + empty list rows '1 -' / '2 -'.","tts_text":"بس الأهم: الـ iron بيشتغل catalyst في طريقتين.","screen_text":"Iron: a catalyst"},{"id":"s6l5","visual":"[CORE] New term 1 'Haber-Bosch' · TP: list row '1 - Haber-Bosch method' on cue 'Haber'; stage arrow becomes YK.formula '->[Fe] NH3' + 'ammonia' on cue 'ammonia'. Book p.6.","tts_text":"الأولى طريقة Haber-Bosch، عشان نصنّع الـ ammonia بسرعة.","screen_text":"1 - Haber-Bosch method: manufacture of ammonia"},{"id":"s6l6","visual":"[CORE] New term 2 'Fischer-Tropsch' (water gas waits for s6l7: ≤ 1 new term per line) · TP: list row '2 - Fischer-Tropsch method' on cue 'Fischer'; second stage arrow '[ ? ] ->[Fe] fuel' (dashed box, no text) + custom fuel drop on cue 'fuel'. Book pp.6-7.","tts_text":"والتانية طريقة Fischer-Tropsch: بتحوّل غاز لـ fuel، والـ iron بيساعد فيها.","screen_text":"2 - Fischer-Tropsch method → fuel"},{"id":"s6l7","visual":"[CORE] New term 3 'water gas'. Misconception (te.uses-fe-co #1) · SS: the dashed box fills with 'water gas' on cue 'water'; left small coral 'H₂O' + YK.wrongMark on cue 'بخار' (< 2 s); right YK.molecule 'H2' on cue 'hydrogen' + YK.molecule 'CO' on cue 'carbon', gold 'CO + H₂'; label 'mixture of hydrogen and carbon monoxide' (40). Book p.7.","tts_text":"الغاز ده اسمه water gas… ومش بخار مية، ده hydrogen و carbon monoxide متخلطين.","screen_text":"Water gas: H₂O ✕ · CO + H₂ ✓"},{"id":"s6l8","visual":"[CORE] PAUSE-AND-PREDICT (v6 new case from the reactants, book pp.14-15: N₂ + 3H₂ →[Fe] 2NH₃; ammonia is not named, so the student infers it; lesson asked what CO + H₂ makes) · TP. YK.checkPause in the text panel (question 'A plant passes nitrogen and hydrogen over iron. Which method?', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: YK.icon 'factory'; inputs YK.formula 'N2 + H2' on cue 'nitrogen', Fe over its arrow on cue 'iron', output '?' (no NH₃ drawn); two method cards face-down.","tts_text":"مصنع بيعدّي nitrogen و hydrogen على الـ iron… دي أنهي طريقة؟ وقّفوا وفكّروا. <long pause>","screen_text":"A plant passes nitrogen and hydrogen over iron. Which method?","pause_after_s":2},{"id":"s6l9","visual":"[CORE] Answer · FB: the two cards large; 'Haber-Bosch' flips + YK.rightMark on cue 'Haber'; 'Fischer-Tropsch' stays dim; the factory output '?' becomes YK.formula 'N2 + 3H2 ->[Fe] 2NH3' + 'ammonia' on cue 'ammonia'; 'iron = catalyst' (gold) on cue 'catalyst'. Book pp.6, 14-15.","tts_text":"دي Haber-Bosch: الاتنين بيكوّنوا ammonia، والـ iron فيها catalyst بيسرّع التفاعل.","screen_text":"Haber-Bosch: N₂ + 3H₂ → 2NH₃, iron is the catalyst ✓"},{"id":"s6l10","visual":"[CORE] MICRO-RECAP · TP: YK.takeaway({title:'Economic Importance of Iron and Cobalt', line:'Fe: building, tools · a catalyst in two methods', formula:'->[Fe]', t, pulse:[{word:'catalyst', at:YK.cue('s6l10','catalyst')}]}).","tts_text":"الخلاصة: الـ iron للبنا والأدوات، و catalyst في الطريقتين.","screen_text":"Fe: building, tools · a catalyst in two methods"},{"id":"s6l11","visual":"[CORE] SO-WHAT into recap 2 · FB: segment chip out; camera pulls back to the recap map (no fade).","tts_text":"وقبل ما نروح لجاره، نلم النص التاني بسرعة.","screen_text":"Before iron's neighbour: a quick recap"},{"id":"m2l1","visual":"[CORE] MID-EPISODE RECAP 2 · FB. YK.flow with explicit x/y: row 1 (y 300) = recap-1 nodes 1–4 dimmed (size 32); row 2 (y 640, from x 96) new nodes; edge node 4 → node 5. Node 5 'Cr: non-porous oxide layer' lit on cue 'chromium', mini oxide-skin under it.","tts_text":"الـ chromium محمي بطبقة oxide، non-porous، مقفولة.","screen_text":"Cr: non-porous oxide layer"},{"id":"m2l2","visual":"[CORE] Node 6 'Mn: alloys and compounds' + edge on cue 'manganese'; YK.icon 'rail' under it.","tts_text":"والـ manganese brittle، فبيدخل alloys و compounds بس.","screen_text":"Mn: alloys and compounds"},{"id":"m2l3","visual":"[CORE] Node 7 'Fe: building + catalyst' + edge on cue 'iron'; a small 'Co' tile at the row end pulses (sets up Part 7). Camera move into the PART 7 card (2.5 s pause).","tts_text":"والـ iron للبنا، و catalyst للـ ammonia والوقود.","screen_text":"Fe: building + catalyst","pause_after_s":2.5},{"id":"s7l1","visual":"PART 7/9 · te.uses-fe-co · objective: Explain the uses of cobalt and cobalt 60 · [CORE] Segment card in m2l3's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 7 OF 9', title:'Economic importance of iron and cobalt'}) + objective line (Cairo 600 40) under it; the card collapses into YK.chip(ctx, 96, 64, 'Economic importance of iron and cobalt', {kind:'segment', align:'left'}), on until the segment's micro-recap. Line · FB: YK.icon 'magnet' on cue 'magnets', YK.icon 'battery' on cue 'وبطاريات', custom hospital cross on cue 'tumors' converge on a '?' card on cue 'مين'.","tts_text":"عنصر واحد بيعمل magnets وبطاريات، وبيعالج الـ tumors كمان. مين؟","screen_text":"Magnets, car batteries, tumour treatment: one element?"},{"id":"s7l2","visual":"[CORE] SS (E7, first-mentioned left): YK.elementCard Co (left) and Fe (right), config:''; YK.magnet field lines flow around both on cue 'بيتمغنط' (v1 needle 'بيتمغنطوا' is not in tts); label 'magnets' on cue 'magnets'. Book p.7.","tts_text":"الـ cobalt زي الـ iron، بيتمغنط، فالـ magnets بتتعمل منه.","screen_text":"Cobalt, like iron, can be magnetized → magnets"},{"id":"s7l3","visual":"[TRIM] TP: YK.icon 'battery' (420) + 'Co' tag on cue 'batteries'; label 'modern dry batteries used in cars'. Book p.7.","tts_text":"وكمان في الـ dry batteries الحديثة بتاعة العربيات.","screen_text":"Modern dry batteries used in cars"},{"id":"s7l4","visual":"PREREQ phys.radioactivity-gamma [RECAP-PREREQ] TP, ≤ 8 s. YK.chip prereq 'Radioactivity and gamma rays'. The short's nucleus: packed proton/neutron discs jittering (YK.rng), label 'unstable nucleus' on cue 'unstable'; a violet wavy ray leaves on cue 'radiation'; 'radioactive isotope' (gold) on cue 'radioactive'. Reference only.","tts_text":"فاكرين الـ radioactive isotope؟ الـ nucleus بتاعه unstable، فبيطلّع radiation لوحده.","screen_text":"Radioactive isotope: unstable nucleus → radiation"},{"id":"s7l5","visual":"[CORE] FB: 12 small nucleus glyphs in one row (x 160–1760); YK.label '12' (mono 72) on cue 'اتناشر' (a static label, not YK.counter); the 12th enlarges, gold label 'cobalt 60' on cue 'ستين'. Book p.7.","tts_text":"والـ cobalt ليه اتناشر radioactive isotopes، أهمهم الـ cobalt ستين.","screen_text":"Cobalt: 12 radioactive isotopes · cobalt 60"},{"id":"s7l6","visual":"[CORE] TP: YK.icon 'gamma' source (left of stage) sends the short's violet ray straight through a custom steel block on cue 'gamma'; label 'high penetrating power' on cue 'penetrating'. Book p.7.","tts_text":"وده بيطلّع gamma rays، ليها penetrating power عالية، بتعدّي جوه المواد.","screen_text":"Gamma rays: high penetrating power"},{"id":"s7l7","visual":"[CORE] TP: uses row 1 on the stage: custom food crate on cue 'الأكل' + label 'food preserving'; YK.icon 'factory' product with a ✓ (YK.rightMark small) on cue 'جودة' + 'quality of industrial products'. Book p.7.","tts_text":"فبيحفظوا بيه الأكل، ويكشفوا جودة المنتجات الصناعية.","screen_text":"Food preserving · quality of industrial products"},{"id":"s7l7b","visual":"[CORE] Misconception (te.uses-fe-co #3: food preserved with Co-60 gamma rays becomes radioactive) · TP: uses row 1 of s7l7 stays (food crate + factory product); the short's violet ray passes through both on cue 'gamma'; a small coral radiation trefoil (custom) above the crate + YK.wrongMark on cue 'مش' (< 2 s); label 'do not become radioactive' (Cairo 800 40, gold) on cue 'radioactive'. Row 2 (s7l8) unchanged.","tts_text":"وخلي بالكم: الأكل والمنتجات اللي بتتعرض للـ gamma rays مش بتبقى radioactive خالص.","screen_text":"Food and products exposed to gamma rays do not become radioactive"},{"id":"s7l8","visual":"[CORE] FB: uses row 2: a welded steel PLATE (custom; not a pipe, the pipe is the predict case) with a hidden crack revealed by the rays on cue 'الشروخ' + 'cracks and welding connections'; the short's body silhouette, beam converging on the coral tumour spot on cue 'tumors' + 'diagnosis and treatment of tumors'. Book p.7.","tts_text":"ويكشفوا الشروخ ووصلات اللحام، وفي الطب يشخّصوا ويعالجوا الـ tumors كمان.","screen_text":"Cracks and welding connections · diagnosis and treatment of tumors"},{"id":"s7l9","visual":"[CORE] Misconception (te.uses-fe-co #2) · TP: coral 'magnetic' + YK.wrongMark on cue 'لأ' (< 2 s); 'gamma rays' (gold) + YK.rightMark on cue 'gamma'.","tts_text":"ناس فاكرة الـ cobalt ستين مهم عشان magnetic… لأ، الـ gamma rays هي السبب.","screen_text":"Because it is magnetic? ✕ · Gamma rays ✓"},{"id":"s7l10","visual":"[CORE] PAUSE-AND-PREDICT (new case: short = strawberries, lesson = mangoes; pipe not shown before) · TP. YK.checkPause in the text panel (question 'Check a weld inside a steel pipe without cutting it. Use what?', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: YK.icon 'pipe' (long) with a weld ring, custom engineer silhouette.","tts_text":"مهندس عايز يكشف لحام ماسورة steel من غير ما يقطعها. يستخدم إيه؟ وقّفوا وفكّروا. <long pause>","screen_text":"Check a weld inside a steel pipe without cutting it. Use what?","pause_after_s":2},{"id":"s7l11","visual":"[CORE] Answer · FB: the gamma source beside the pipe; rays pass through and a crack lights up on the far side on cue 'وتكشفه'; YK.rightMark; reason 'high penetrating power' on cue 'بتعدّي'.","tts_text":"الـ cobalt ستين: الـ gamma rays بتاعته بتعدّي جوه الـ steel وتكشفه.","screen_text":"Cobalt 60: gamma rays pass through the steel ✓"},{"id":"s7l12","visual":"[CORE] MICRO-RECAP · TP: YK.takeaway({title:'Economic Importance of Iron and Cobalt', line:'Co: magnets, batteries · cobalt 60: gamma rays', t, pulse:[{word:'gamma rays', at:YK.cue('s7l12','gamma')}]}).","tts_text":"الخلاصة: الـ cobalt للـ magnets، والـ cobalt ستين للـ gamma rays بتاعته.","screen_text":"Co: magnets, batteries · cobalt 60: gamma rays"},{"id":"s7l13","visual":"[CORE] SO-WHAT · FB: the battery icon gains a circular recharge arrow (YK.arrow curved); strip highlight Co → Ni on cue 'nickel'; segment chip out; camera move into the PART 8 card (2.5 s pause).","tts_text":"والعنصر الجاي في بطاريات بتتشحن: الـ nickel نفسه.","screen_text":"Next: nickel","pause_after_s":2.5},{"id":"s8l1","visual":"PART 8/9 · te.uses-ni · objective: Explain the uses of nickel and the reason for each · [CORE] Segment card in s7l13's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 8 OF 9', title:'Economic importance of nickel'}) + objective line (Cairo 600 40) under it; the card collapses into YK.chip(ctx, 96, 64, 'Economic importance of nickel', {kind:'segment', align:'left'}), on until the segment's micro-recap. Line · FB: YK.icon 'battery' (560) whose charge bar fills and drains; tally marks '1' on cue 'مرة', '2' on cue 'واتنين', '10' on cue 'وعشرة' (YK.label mono 64); '?' on cue 'إيه'.","tts_text":"بطارية بتشحنها مرة واتنين وعشرة… جواها إيه؟","screen_text":"A battery you can recharge. What is inside?"},{"id":"s8l2","visual":"[CORE] TP: battery cutaway, two layers labelled 'nickel' (cue 'nickel') and 'cadmium' (cue 'cadmium'); 'can be recharged' on cue 'بتتشحن'. Book p.7.","tts_text":"جواها nickel و cadmium: بطارية بتتشحن تاني وتالت.","screen_text":"Nickel–cadmium battery: can be recharged"},{"id":"s8l3","visual":"[CORE] TP: ALLOY MODEL: steel lattice + 3 Ni discs drop into sites on cue 'steel'; 'alloy' tag; custom rust spots and acid drops bounce off on cues 'rust' and YK.cue('s8l3','acids'); labels 'hard', 'resist rust', 'resist acids'. Book p.7.","tts_text":"والـ nickel مع الـ steel بيدّي alloys جامدة، ضد الـ rust والـ acids كمان.","screen_text":"Ni–steel alloys: hard, resist rust and the effect of acids"},{"id":"s8l4","visual":"[CORE] FB: a custom helical heating coil glowing (heatRed → molten tween); label 'Ni–Cr alloy' on cue 'alloy', 'heating coils' on cue 'heating', 'electric furnaces' on cue 'والأفران'. Book p.7.","tts_text":"والـ nickel مع الـ chromium بيعمل alloy للـ heating coils والأفران الكهربا.","screen_text":"Ni–Cr alloys: heating coils, electric furnaces"},{"id":"s8l5","visual":"[CORE] Misconception (te.uses-ni #1) · TP: coral 'good conductor?' + YK.wrongMark on cue 'لأ', < 2 s.","tts_text":"ناس فاكرة إن السبب إنه conductor كويس… لأ.","screen_text":"Because it is a good conductor? ✕"},{"id":"s8l6","visual":"[CORE] TP: the HEAT GAUGE of Part 1 at max; the coil stays bright through a timelapse (no rust spots), 'resists corrosion at high temperature' (mint) + YK.rightMark on cue 'corrosion'. NO O-bounce or oxide-skin drawing (a mechanism beyond the book). Book p.7.","tts_text":"السبب إنه بيقاوم الـ corrosion في الحرارة العالية.","screen_text":"Resists corrosion at high temperature ✓"},{"id":"s8l7","visual":"[CORE] FB: PLATING MODEL of Part 3 on a dull metal plate, now a nickel-silver sweep on cue 'plating'; labels 'protects from rust' on cue 'rust', 'beautiful appearance' on cue 'ويجمّلها'. Book p.7.","tts_text":"وبيعملوا بيه plating لـ metals تانية، يحميها من الـ rust ويجمّلها.","screen_text":"Nickel plating: protects from rust, beautiful appearance"},{"id":"s8l8","visual":"[CORE] New term 1 'finely divided'. Misconception (te.uses-ni #2) · TP: custom nickel lump crumbles into fine powder (≈ 300 seeded dots, gold outline) on cue 'finely'; small coral 'lump' + YK.wrongMark on cue 'حتة'; 'finely divided nickel' + 'catalyst' (gold) on cue 'catalyst'. No 'more surface' text (not in the book). Book p.7.","tts_text":"والـ nickel الـ finely divided، بودرة ناعمة مش حتة، بيشتغل catalyst للزيوت.","screen_text":"Finely divided nickel: a catalyst"},{"id":"s8l9","visual":"[CORE] New term 2 'hydrogenation' (≥ 1 s after term 1) · FB: YK.surface(ctx, 360, 760, 1200, {metal:'Ni', molecules:[{mol:'H2', col:2, p}, {mol:'H2', col:5, p}]}) + custom oil-molecule chain landing beside them; they join on cue YK.cue('s8l9','hydrogen',1) (needle 'hydrogen' alone hits 'hydrogenation' first); label 'hydrogenation of oil' on cue 'hydrogenation'. Book p.7.","tts_text":"في الـ hydrogenation، الـ hydrogen بيضاف للزيت بسرعة على البودرة دي.","screen_text":"Hydrogenation processes of oil"},{"id":"s8l10","visual":"[CORE] PAUSE-AND-PREDICT (new case: short = electric furnace, lesson = bakery oven, handlebars) · TP. YK.checkPause in the text panel (question 'A steel tank will hold an acid. Which nickel use fits?', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: custom steel tank labelled 'acid'; four nickel-use cards face-down.","tts_text":"تانك steel هيتحط فيه acid… أنهي استخدام للـ nickel ينفع هنا؟ وقّفوا وفكّروا. <long pause>","screen_text":"A steel tank will hold an acid. Which nickel use fits?","pause_after_s":2},{"id":"s8l11","visual":"[CORE] Answer · FB: the 'Ni–steel alloy' card flips + YK.rightMark on cue 'steel'; acid drops bounce off the tank wall on cue 'acids'.","tts_text":"الـ alloy بتاعه مع الـ steel: جامد، وبيقاوم تأثير الـ acids كمان.","screen_text":"Ni–steel alloy: resists the effect of acids ✓"},{"id":"s8l12","visual":"[CORE] MICRO-RECAP · TP: YK.takeaway({title:'Economic Importance of Nickel', line:'Ni: Ni–Cd battery · alloys · plating · catalyst', t, pulse:[{word:'catalyst', at:YK.cue('s8l12','catalyst')}]}); stage: battery, spring, plate, powder icons (small).","tts_text":"الخلاصة: الـ nickel في البطاريات، والـ alloys، والـ plating، و catalyst للزيوت.","screen_text":"Ni: Ni–Cd battery · alloys · plating · catalyst"},{"id":"s8l13","visual":"[CORE] SO-WHAT · FB: strip highlight moves to Cu and Zn on cue 'metal' / 'الصدا'; segment chip out; camera move into the PART 9 card (2.5 s pause).","tts_text":"وآخر اتنين: أقدم metal عرفناه، واللي بيحمي الـ iron من الصدا.","screen_text":"Last two: the first discovered metal, and iron's protector","pause_after_s":2.5},{"id":"s9l1","visual":"PART 9/9 · te.uses-cu-zn · objective: State the uses of copper, zinc and their compounds · [CORE] Segment card in s8l13's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 9 OF 9', title:'Economic importance of copper and zinc'}) + objective line (Cairo 600 40) under it; the card collapses into YK.chip(ctx, 96, 64, 'Economic importance of copper and zinc', {kind:'segment', align:'left'}), on until the segment's micro-recap. Line · FB: custom ancient statue silhouette (dark), '?' card on cue 'مين'.","tts_text":"أول metal الإنسان اكتشفه في التاريخ… تفتكروا مين؟","screen_text":"The first discovered metal?"},{"id":"s9l2","visual":"[CORE] New term 1 'bronze' · TP: ALLOY MODEL with copper lattice (YK.atomColor('Cu')) on cue 'copper' + tin discs on cue 'tin'; the block morphs into the statue, now bronze-toned, label 'bronze alloy' on cue 'bronze'; text panel 'Copper: the first discovered metal'. Book p.7.","tts_text":"الـ copper! ومع الـ tin، بيدّي الـ bronze alloy المشهور.","screen_text":"Copper: the first discovered metal · copper + tin = bronze alloy"},{"id":"s9l3","visual":"[CORE] Misconception (te.uses-cu-zn #1) · SS: left coral 'Cu + Zn' + YK.wrongMark on cue 'غلط' (< 2 s); right gold 'Cu + Sn' + YK.rightMark on cue 'tin'.","tts_text":"ناس كتير فاكرة bronze يعني copper و zinc… غلط، الـ tin هو التاني.","screen_text":"Copper + zinc ✕ · Copper + tin ✓"},{"id":"s9l4","visual":"[CORE] TP: YK.icon 'cable' with cyan electron dots flowing on cue 'conductor'; YK.icon 'coin' stack on cue 'والعملات'; labels 'electric cables', 'coins'. Book p.7.","tts_text":"والـ copper conductor كويس للكهربا، فبيعملوا منه الـ cables والعملات.","screen_text":"Good conductor of electricity → electric cables, coins"},{"id":"s9l5","visual":"[CORE] TP: YK.icon 'flask' 'CuSO₄' + three tags on cues 'insecticide', 'fungicide', 'بينقّي' ('purification of water'); leaf reused from Part 5, custom insect and drop glyphs. Book p.7.","tts_text":"والـ copper sulphate بيقتل الحشرات والفطريات، insecticide و fungicide، وبينقّي المية.","screen_text":"Copper II sulphate CuSO₄: insecticide, fungicide, purification of water"},{"id":"s9l6","visual":"[CORE] New term 2 \"Fehling's solution\" · FB: YK.tube with color C.fehling, color2 C.molten, mix: prog from cue 'برتقاني' (1.5 s) (lab.js example); a 'glucose' drop on cue 'glucose'; label \"Fehling's solution\" on cue 'Fehling'. Book colour change, not an ion colour (G37). Book p.7.","tts_text":"وفيه مركّب copper اسمه Fehling's solution، بيكشف الـ glucose: لونه الأزرق بيقلب برتقاني.","screen_text":"Fehling's solution: detects glucose, blue → orange"},{"id":"s9l7","visual":"[CORE] New term 3 'galvanizing' · TP: custom grey iron sheet dipped into a YK.beaker of grey molten zinc, comes out with a zinc coat; rain drops bounce off; label 'galvanizing' on cue 'galvanizing', 'protects from rusting' on cue 'rusting'. Book p.7.","tts_text":"أما الـ zinc، فبيعملوا بيه galvanizing للـ metals، عشان الـ rusting ميوصلهاش.","screen_text":"Zinc: galvanizing other metals → protects them from rusting"},{"id":"s9l8","visual":"[TRIM] TP: YK.icon 'flask' 'ZnO' + labels 'paints' (custom tin), 'rubber' (custom tyre ring) on cue 'rubber', 'cosmetics' (YK.icon 'sunscreen') on cue 'التجميل'. Book p.8.","tts_text":"ومن مركّباته zinc oxide، في البويات والـ rubber ومستحضرات التجميل.","screen_text":"Zinc oxide ZnO: paints, rubber, cosmetics"},{"id":"s9l9","visual":"[TRIM] FB: YK.icon 'flask' 'ZnS' + a glowing paint stroke (YK.glow) 'illuminating paints' on cue 'بتنوّر' + custom X-ray screen with the em-spectrum short's bone glyph 'X-ray screens' on cue 'X'. Book p.8.","tts_text":"والـ zinc sulphide للبويات اللي بتنوّر وشاشات الـ X-ray كمان.","screen_text":"Zinc sulphide ZnS: illuminating paints, X-ray screens"},{"id":"s9l10","visual":"[CORE] PAUSE-AND-PREDICT (new case: short = iron fence, lesson = sugar-free drink) · TP. YK.checkPause in the text panel (question 'Fehling's solution + a juice: blue turns orange. What does it contain?', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: juice glass (YK.beaker) + YK.tube already orange.","tts_text":"حطّينا Fehling's solution على عصير، واللون قلب برتقاني. فيه إيه؟ وقّفوا وفكّروا. <long pause>","screen_text":"Fehling's solution + a juice: blue turns orange. What does it contain?","pause_after_s":2},{"id":"s9l11","visual":"[CORE] Answer · FB (keeps the shot rhythm if s9l8–9 are trimmed): 'glucose' (Cairo 1000 96) + YK.rightMark on cue 'glucose'; reason 'blue → orange' with two colour chips (C.fehling → C.molten).","tts_text":"فيه glucose، عشان اللون قلب من أزرق لبرتقاني.","screen_text":"Glucose ✓"},{"id":"s9l12","visual":"[CORE] MICRO-RECAP · TP: YK.takeaway({title:'Economic Importance of Copper and Zinc', line:'Cu: bronze, electricity · Zn: galvanizing', t, pulse:[{word:'galvanizing', at:YK.cue('s9l12','galvanizing')}]}).","tts_text":"الخلاصة: الـ copper للـ bronze والكهربا، والـ zinc للـ galvanizing ضد الصدا.","screen_text":"Cu: bronze, electricity · Zn: galvanizing"},{"id":"s9l13","visual":"[CORE] SO-WHAT · FB: segment chip out; camera pulls back from the strip into the closing flow (no fade).","tts_text":"كده لفّينا العشرة. يلا نربطهم ببعض.","screen_text":"All ten: one chain"},{"id":"z1","visual":"[CORE] CLOSING SUMMARY · FB. YK.flow with explicit x/y: header node 'property → use' (y 200, centre) on line start; 5 property nodes will fill a row at y 480 (x 96–1824, node size 36) with element tiles (YK.label, mono 44) under each.","tts_text":"القاعدة: كل عنصر ليه خاصية، والخاصية بتحدد استخدامه.","screen_text":"Each element: a property → a use"},{"id":"z2","visual":"[CORE] Node 1 'Hard alloys' lit on cue 'alloys'; tiles appear on their spoken names only: Sc ('scandium'), Ti ('titanium'), V ('vanadium'), Mn ('manganese').","tts_text":"عناصر بتدّي alloys جامدة، زي الـ scandium والـ titanium والـ vanadium والـ manganese كده.","screen_text":"Hard alloys: Sc, Ti, V, Mn"},{"id":"z3","visual":"[CORE] Node 2 'Resist air / protect' + edge on cue 'بتقاوم'; tiles Cr (mini oxide skin) on cue 'chromium', Zn (zinc coat) on cue 'zinc'.","tts_text":"وعناصر بتقاوم الهوا أو بتحمي غيرها، زي الـ chromium والـ zinc مثلًا.","screen_text":"Resist the air, or protect others: Cr, Zn"},{"id":"z4","visual":"[CORE] Node 3 'Catalysts' + edge on cue 'catalysts'; tiles Fe ('iron'), Ni ('nickel'), V₂O₅ ('vanadium').","tts_text":"وفيه catalysts: الـ iron، والـ nickel، والـ vanadium pentoxide كمان.","screen_text":"Catalysts: V₂O₅, Fe, Ni"},{"id":"z5","visual":"[CORE] Node 4 'Conduct electricity' + edge on cue 'conductor'; tile Cu on cue 'copper', YK.icon 'cable' (small) under it.","tts_text":"والـ copper conductor كويس، فبيدخل في الـ cables والعملات.","screen_text":"Conduct electricity: Cu"},{"id":"z6","visual":"[CORE] Node 5 'Gamma rays' + edge on cue 'gamma'; tile 'Co-60' on cue 'cobalt'; the whole row visible left → right.","tts_text":"والـ cobalt ستين بالـ gamma rays بيكشف وبيعالج.","screen_text":"Cobalt 60: gamma rays"},{"id":"z7","visual":"[CORE] BIG QUESTION ANSWERED · FB: the cold-open question 'Only 7%. Why such high economic importance?' returns top-left (Cairo 1000 56); under it the answer (screen_text, gold 'each property fits a use'); the 7% crust slice (c3) links by thin lines to the 5 nodes on cue 'economic'.","tts_text":"عشان كده، سبعة في المية بس، وليهم economic importance عالية جدًا.","screen_text":"Nearly 7%, but high economic importance: each property fits a use"},{"id":"z8","visual":"[CORE] CLOSING RECALL 1 (give reasons, book exercise style) · TP. YK.checkPause in the text panel (question 'Give reasons: titanium is used in dental implants.', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: YK.icon 'implant'.","tts_text":"أول سؤال: ليه الـ titanium في implants السنان؟ وقّفوا وفكّروا. <long pause>","screen_text":"Give reasons: titanium is used in dental implants.","pause_after_s":2},{"id":"z9","visual":"[CORE] Answer · TP: 'Inert' (mint) + YK.rightMark on cue 'inert'; 'the body does not eject it, no poisoning'.","tts_text":"عشان inert: الجسم مبيرفضوش، ومفيش أي تسمم.","screen_text":"Inert: the body does not eject it, no poisoning ✓"},{"id":"z10","visual":"[CORE] CLOSING RECALL 2 (new case) · FB: custom suspension-bridge cables with a grey zinc coat; YK.checkPause question top-left (x 96) with the ring at the right.","tts_text":"كابلات كوبري steel اتغطّت بالـ zinc. اسمها إيه، وبتعمل إيه؟ وقّفوا وفكّروا. <long pause>","screen_text":"A bridge's steel cables get a zinc coat. What is it called, and why?","pause_after_s":2},{"id":"z11","visual":"[CORE] Answer · FB: 'galvanizing' (gold) + YK.rightMark on cue 'galvanizing'; rain bounces off the cable coat.","tts_text":"اسمها galvanizing، وبتحمي الـ steel من الـ rusting كده.","screen_text":"Galvanizing: protects the steel from rusting ✓"},{"id":"z12","visual":"[CORE] CLOSING RECALL 3 (give reasons, book Evaluation Q7.2 p.27 style) · TP. YK.checkPause in the text panel (question 'Give reasons: chromium is active, but resists the atmospheric air.', answer '' : the answer comes on the next line), start = YK.cue(<this line>, 'وقّفوا'), dur = to the next line's start (think ring runs through the 2 s stitched silence). Stage: the chrome tap.","tts_text":"وآخر سؤال: ليه الـ chromium active، ومع كده بيقاوم الهوا؟ وقّفوا وفكّروا. <long pause>","screen_text":"Give reasons: chromium is active, but resists the atmospheric air.","pause_after_s":2},{"id":"z13","visual":"[CORE] Answer · FB: the Part 4 oxide-skin model returns (closed layer, O bouncing off) + YK.rightMark on cue 'non'; 0.8 s tail holds the frame.","tts_text":"عشان الـ oxide بتاعه أكبر volume، فبيعمل طبقة non-porous بتحميه.","screen_text":"Larger oxide volume → non-porous layer → no continued reaction ✓"}],"logline":"Ten elements make up nearly 7% of the earth's crust, yet they build jets, rails, implants and batteries. 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titanium في بُق حد قضيب قطر وعلبة\nكانز في إيدك\nورا كل واحدة فيهم عنصر من العشرة اللي\nعرفناهم\nكلهم سوا حوالي سبعة في المية بس من وزن الـ\nearth's crust كله\nطب إزاي حاجة قليلة كده يبقى ليها economic\nimportance عالية\nحلقتنا الـ economic importance بتاعة الـ\ntransition series الأولى عنصر عنصر\nأول واحد الـ scandium قليل جدًا ومفرّق في\nالأرض فايدته إيه\nشوية scandium صغيرين على الـ aluminium\nبيدّوا alloy خفيف وجامد جدًا\nوالـ alloy يعني metal متخلط بعناصر تانية\nوالـ alloy ده لطيارات الـ MiG الحربية\nوفي لمبات الـ mercury vapour بيدّي نور شبه\nالشمس للتصوير بالليل\nتاني عنصر الـ titanium جامد زي الـ steel\nبس الـ density بتاعته أقل\nفالـ alloys بتاعته مع الـ aluminium بتدخل\nفي الطيارات وسفن الفضاء\nليه في الحرارة العالية الـ aluminium بيلين\nوالـ titanium الـ durability بتاعته ثابتة\nوفي implants السنان والمفاصل الصناعية ناس\nكتير فاكرة إنه عشان جامد غلط\nالسبب إنه inert مبيتفاعلش فالجسم مبيرفضوش\nومفيش تسمم\nفاكرين الـ ultraviolet أشعة مش بنشوفها بس\nبتأذي الجلد\nوالـ titanium dioxide مش الـ metal في\nكريمات الشمس يمنع الـ ultraviolet عنّا\nطب frame عجلة سباق جامد زي الـ steel وأخف\nتختاروا إيه وقّفوا وفكّروا\nالـ titanium جامد زي الـ steel والـ\ndensity بتاعته أقل\nالخلاصة الـ scandium بيقوّي الـ aluminium\nوالـ titanium inert و durable في الحرارة\nالاتنين قوّوا الـ aluminium طب الـ steel\nمين بيقوّيه\nسوست العربية بتتضغط آلاف المرات ليه\nمبتتكسرش\nالسر نسبة صغيرة من الـ vanadium بتتحط على\nالـ steel نفسه\nفيطلع alloy جامد جدًا وبيقاوم الـ\ncorrosion يعني التآكل\nفاكرين الـ catalyst بيسرّع التفاعل وبيفضل\nزي ما هو\nوأهم مركّب للـ vanadium هو الـ vanadium\npentoxide وده catalyst مهم\nوكمان بيدخل dyes في صناعة السيراميك\nوالإزاز\nوبيدخل كمان في صناعة magnetic conductors\nقوية\nناس كتير فاكرة إنه dye وبس لأ ده catalyst\nكمان\nمصنع إزاز ومصنع كيماويات الاتنين بيشتروا\nvanadium pentoxide كل واحد عايزه ليه\nوقّفوا وفكّروا\nالإزاز عشان الـ dyes والمصنع التاني عشان\ncatalyst مش dye وبس\nالخلاصة الـ vanadium بيقوّي الـ steel والـ\nvanadium pentoxide بيتستخدم catalyst و\ndyes كمان\nوجاره على طول الـ chromium استخداماته إيه\nالحنفية اللي بتلمع والجزمة الجلد الاتنين\nفيهم chromium إزاي\nالـ chromium بيستخدموه في الـ metal\nplating يعني يغلّفوا بيه metals تانية\nوكمان بيستخدموه في الـ leather tanning\nيعني دبغ الجلود\nومن مركّباته chromium تلاتة oxide فيه\nاتنين chromium وتلاتة oxygen للـ dyes كمان\nفاكرين الـ oxidizing agent بيدّي oxygen\nلغيره فيأكسده\nوالمركّب التاني الـ potassium dichromate\nمش reducing agent ده oxidizing agent\nبيأكسد غيره\nطب مصنع بويات محتاج مركّب chromium للـ\ndyes ياخد أنهي واحد وقّفوا وفكّروا\nالـ chromium تلاتة oxide أما الـ potassium\ndichromate فشغلته oxidizing agent مش dye\nخالص\nالخلاصة الـ chromium للـ plating والـ\ntanning وأكسيده للـ dyes كمان\nقبل ما نشوف سر لمعة الـ chromium نلم اللي\nفات بسرعة\nالـ scandium بيدّي الـ aluminium alloy\nخفيف وجامد\nوالـ titanium inert في الجسم و durable في\nالحرارة\nوالـ vanadium بيقوّي الـ steel والـ\nvanadium pentoxide بيبقى catalyst مهم\nوالـ chromium بيدخل في الـ plating والـ\ntanning كمان\nحنفية الـ chromium بتفضل تلمع سنين في\nالهوا إزاي\nالكتاب بيقول على الـ chromium إنه\nchemically active يعني بيتفاعل بسهولة\nناس كتير فاكرة إنه مبيتفاعلش أصلًا غلط\nهو بيتفاعل مع الـ oxygen ويتكوّن metal\noxide على سطحه\nوالـ molecular volume بتاع الـ oxide أكبر\nمن الـ metal atoms نفسها\nفالطبقة بتقفل كل الفراغات وتبقى non-porous\nمفيهاش مسام\nفالـ oxygen مبيوصلش للـ metal تاني\nوالتفاعل بيقف عند السطح\nطب metal الـ oxide بتاعه volume أصغر من\nالـ atoms هيتحمي وقّفوا وفكّروا\nلأ الطبقة هتبقى porous فالـ oxygen يعدّي\nوالتفاعل يكمّل\nنفس النتيجة في الـ rust على الـ iron طبقته\nporous فالـ rusting بيكمّل\nيعني الـ oxide أكبر volume فالطبقة\nnon-porous والـ chromium محمي\nطب جاره الـ manganese حكايته إيه\nالـ manganese عمره ما بيتستخدم لوحده ليه\nناس فاكرة إنه بيتستخدم pure لأ ده brittle\nبيتكسر لو اتخبط\nفبيدخل دايمًا في alloys أو compounds بس\nالـ ferromanganese أجمد من الـ steel\nفبيعملوا منه الـ railway track بتاع القطر\nومع الـ aluminium بيعمل alloy بيقاوم الـ\ncorrosion للكانز\nوفي الـ dry cell فيه manganese dioxide\noxidizing agent قوي\nوالـ potassium permanganate بيستخدموه\nantiseptic يعني مطهّر\nأما الـ manganese sulphate فده fungicide\nبيقتل الفطريات\nصيدلية بتبيع مركّب manganese بيستخدموه\nantiseptic أنهي واحد وقّفوا وفكّروا\nالـ potassium permanganate أما الـ\nsulphate فده fungicide للفطريات\nالخلاصة الـ manganese brittle فبيشتغل في\nalloys و compounds بس\nوبعده العنصر اللي الباب كله بيدور حواليه\nالـ iron نفسه\nمن الكوبري لأدوات الجرّاح كله iron وكمان\nبيساعد نعمل fuel إزاي\nالـ iron في الـ reinforced concrete وأبراج\nالكهربا والسكاكين والأدوات الجراحية\nوكمان مواسير البنادق والمدافع كلها من الـ\niron برضه\nبس الأهم الـ iron بيشتغل catalyst في\nطريقتين\nالأولى طريقة Haber-Bosch عشان نصنّع الـ\nammonia بسرعة\nوالتانية طريقة Fischer-Tropsch بتحوّل غاز\nلـ fuel والـ iron بيساعد فيها\nالغاز ده اسمه water gas ومش بخار مية ده\nhydrogen و carbon monoxide متخلطين\nمصنع بيعدّي nitrogen و hydrogen على الـ\niron دي أنهي طريقة وقّفوا وفكّروا\nدي Haber-Bosch الاتنين بيكوّنوا ammonia\nوالـ iron فيها catalyst بيسرّع التفاعل\nالخلاصة الـ iron للبنا والأدوات و catalyst\nفي الطريقتين\nوقبل ما نروح لجاره نلم النص التاني بسرعة\nالـ chromium محمي بطبقة oxide non-porous\nمقفولة\nوالـ manganese brittle فبيدخل alloys و\ncompounds بس\nوالـ iron للبنا و catalyst للـ ammonia\nوالوقود\nعنصر واحد بيعمل magnets وبطاريات وبيعالج\nالـ tumors كمان مين\nالـ cobalt زي الـ iron بيتمغنط فالـ\nmagnets بتتعمل منه\nوكمان في الـ dry batteries الحديثة بتاعة\nالعربيات\nفاكرين الـ radioactive isotope الـ nucleus\nبتاعه unstable فبيطلّع radiation لوحده\nوالـ cobalt ليه اتناشر radioactive\nisotopes أهمهم الـ cobalt ستين\nوده بيطلّع gamma rays ليها penetrating\npower عالية بتعدّي جوه المواد\nفبيحفظوا بيه الأكل ويكشفوا جودة المنتجات\nالصناعية\nوخلي بالكم الأكل والمنتجات اللي بتتعرض للـ\ngamma rays مش بتبقى radioactive خالص\nويكشفوا الشروخ ووصلات اللحام وفي الطب\nيشخّصوا ويعالجوا الـ tumors كمان\nناس فاكرة الـ cobalt ستين مهم عشان\nmagnetic لأ الـ gamma rays هي السبب\nمهندس عايز يكشف لحام ماسورة steel من غير\nما يقطعها يستخدم إيه وقّفوا وفكّروا\nالـ cobalt ستين الـ gamma rays بتاعته\nبتعدّي جوه الـ steel وتكشفه\nالخلاصة الـ cobalt للـ magnets والـ cobalt\nستين للـ gamma rays بتاعته\nوالعنصر الجاي في بطاريات بتتشحن الـ nickel\nنفسه\nبطارية بتشحنها مرة واتنين وعشرة جواها إيه\nجواها nickel و cadmium بطارية بتتشحن تاني\nوتالت\nوالـ nickel مع الـ steel بيدّي alloys\nجامدة ضد الـ rust والـ acids كمان\nوالـ nickel مع الـ chromium بيعمل alloy\nللـ heating coils والأفران الكهربا\nناس فاكرة إن السبب إنه conductor كويس لأ\nالسبب إنه بيقاوم الـ corrosion في الحرارة\nالعالية\nوبيعملوا بيه plating لـ metals تانية\nيحميها من الـ rust ويجمّلها\nوالـ nickel الـ finely divided بودرة ناعمة\nمش حتة بيشتغل catalyst للزيوت\nفي الـ hydrogenation الـ hydrogen بيضاف\nللزيت بسرعة على البودرة دي\nتانك steel هيتحط فيه acid أنهي استخدام للـ\nnickel ينفع هنا وقّفوا وفكّروا\nالـ alloy بتاعه مع الـ steel جامد وبيقاوم\nتأثير الـ acids كمان\nالخلاصة الـ nickel في البطاريات والـ\nalloys والـ plating و catalyst للزيوت\nوآخر اتنين أقدم metal عرفناه واللي بيحمي\nالـ iron من الصدا\nأول metal الإنسان اكتشفه في التاريخ\nتفتكروا مين\nالـ copper ومع الـ tin بيدّي الـ bronze\nalloy المشهور\nناس كتير فاكرة bronze يعني copper و zinc\nغلط الـ tin هو التاني\nوالـ copper conductor كويس للكهربا\nفبيعملوا منه الـ cables والعملات\nوالـ copper sulphate بيقتل الحشرات\nوالفطريات insecticide و fungicide وبينقّي\nالمية\nوفيه مركّب copper اسمه Fehling's solution\nبيكشف الـ glucose لونه الأزرق بيقلب\nبرتقاني\nأما الـ zinc فبيعملوا بيه galvanizing للـ\nmetals عشان الـ rusting ميوصلهاش\nومن مركّباته zinc oxide في البويات والـ\nrubber ومستحضرات التجميل\nوالـ zinc sulphide للبويات اللي بتنوّر\nوشاشات الـ X-ray كمان\nحطّينا Fehling's solution على عصير واللون\nقلب برتقاني فيه إيه وقّفوا وفكّروا\nفيه glucose عشان اللون قلب من أزرق\nلبرتقاني\nالخلاصة الـ copper للـ bronze والكهربا\nوالـ zinc للـ galvanizing ضد الصدا\nكده لفّينا العشرة يلا نربطهم ببعض\nالقاعدة كل عنصر ليه خاصية والخاصية بتحدد\nاستخدامه\nعناصر بتدّي alloys جامدة زي الـ scandium\nوالـ titanium والـ vanadium والـ manganese\nكده\nوعناصر بتقاوم الهوا أو بتحمي غيرها زي الـ\nchromium والـ zinc مثلًا\nوفيه catalysts الـ iron والـ nickel والـ\nvanadium pentoxide كمان\nوالـ copper conductor كويس فبيدخل في الـ\ncables والعملات\nوالـ cobalt ستين بالـ gamma rays بيكشف\nوبيعالج\nعشان كده سبعة في المية بس وليهم economic\nimportance عالية جدًا\nأول سؤال ليه الـ titanium في implants\nالسنان وقّفوا وفكّروا\nعشان inert الجسم مبيرفضوش ومفيش أي تسمم\nكابلات كوبري steel اتغطّت بالـ zinc اسمها\nإيه وبتعمل إيه وقّفوا وفكّروا\nاسمها galvanizing وبتحمي الـ steel من الـ\nrusting كده\nوآخر سؤال ليه الـ chromium active ومع كده\nبيقاوم الهوا وقّفوا وفكّروا\nعشان الـ oxide بتاعه أكبر volume فبيعمل\nطبقة non-porous بتحميه","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"series_id":"chem-s3-en.ch1#sessions","episode_no":2,"episode_count":9,"lessons":["chem-s3-en.lesson-phys.radioactivity-gamma","chem-s3-en.lesson-te.chromium-oxide-layer","chem-s3-en.lesson-te.uses-cu-zn","chem-s3-en.lesson-te.uses-fe-co","chem-s3-en.lesson-te.uses-mn","chem-s3-en.lesson-te.uses-ni","chem-s3-en.lesson-te.uses-sc-ti","chem-s3-en.lesson-te.uses-v-cr"]},{"id":"chem-s3-en.video-episode-te-configuration","kind":"episode","version":2,"ord":195,"content_lang":"ar-EG","primary_concept_id":"te.electron-configuration","concepts":[{"concept_id":"te.electron-configuration","role":"primary"},{"concept_id":"te.cr-cu-anomaly","role":"secondary"},{"concept_id":"te.definition","role":"secondary"},{"concept_id":"te.definition-applied","role":"secondary"},{"concept_id":"te.fe2-fe3-mn2-stability","role":"secondary"},{"concept_id":"te.ion-configuration","role":"secondary"},{"concept_id":"te.multiple-oxidation-states","role":"secondary"},{"concept_id":"te.oxidation-states-trend","role":"secondary"}],"title":"Electronic configurations and oxidation states","payload":{"title":"Electronic configurations and oxidation states","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"16:9","format":"episode","script":[{"id":"c1","visual":"[CORE] COLD OPEN · FB. 10 custom tiles Sc → Zn in one row (same look as the te-position strip: YK.roundRect tiles ~150 px, symbol YK.label 64 + Z mono 32, d-block violet edge), x 96–1824, y ≈ 520. Frame 0 is never empty: tiles are on screen at 40% from t = 0 and land left → right with YK.stagger(gap 0.08, dur 0.4). Sc tile glows on YK.cue('c1','scandium'), Zn tile on cue 'zinc'. Camera drift ≤ 2% (E9). Book p.8 table.","tts_text":"عشرة جيران في صف واحد: من الـ scandium، لحد الـ zinc في الآخر.","screen_text":"₂₁Sc → ₃₀Zn"},{"id":"c2","visual":"[CORE] FB strip. On cue 'manganese': Mn tile rises 40 px, gold mono badge above it counts +2 → +7 (YK.counter, 1 s, drawn with YK.label 72 so the 7 is mono) + small tag 'KMnO₄' (book table compound, YK.formula 40) under the tile. On cue 'zinc': Zn tile gets a flat '+2' badge (textDim) + tag 'ZnO'. Book p.8 table + point 4.","tts_text":"الـ manganese في النص بيوصل لسبعة موجب… والـ zinc؟ اتنين بس.","screen_text":"Mn: up to +7 · Zn: only +2"},{"id":"c3","visual":"[CORE] FB strip. On cue 'd-block': violet d-block bracket under all 10 tiles; on cue 'transition': Zn tile slides half out of the bracket with a dashed outline; label 'not a transition element' (coral, Cairo 800 40) under Zn. Book p.11 Exercise 2.","tts_text":"وأغرب من كده: الـ zinc قاعد في الـ d-block، ومش transition element أصلاً!","screen_text":"Zn: in the d-block, but not a transition element"},{"id":"c4","style":"curious","visual":"[CORE] BIG QUESTION · FB. Strip dims to 30%; card centred (Cairo 1000 96, 5 words) 'Same row. Why so different?' on line start; holds through the pause, then shrinks to a small gold tag (returns in z5).","tts_text":"إزاي جيران في نفس الصف يختلفوا كده؟","screen_text":"Same row. Why so different?","pause_after_s":1},{"id":"t1","visual":"[CORE] TITLE CARD, ≤ 4 s on screen (E-structure): YK.titleCard({title:'Electronic configurations and oxidation states', chip:'Unit 3', subtitle:'Chapter 1: Transition Elements', y:300}) from line start to YK.cue('t1','oxidation') + 0.8 s; parts row below it (custom, y 640–1000, 2 columns × 4 rows, x 96 and x 980, each item YK.para Cairo 800 32 (E8 minimum, NOT 28), maxWidth 800, 'n  title_en'): 1 Electronic configuration of the first transition series · 2 Abnormal electronic configuration of chromium and copper · 3 Ions: 4s electrons are lost first · 4 Iron(II) is easily oxidized while manganese(II) is not · 5 Oxidation states from Sc to Zn · 6 Why several oxidation states · 7 Definition of the transition element · 8 Are coinage metals and zinc transition elements?. Then camera move (1.2 s, no fade) onto item 1, which grows into the PART 1 card (held through the rest of the line + the 2.5 s pause).","tts_text":"الحلقة دي عن الـ electronic configuration، والـ oxidation states بتاعتهم.","screen_text":"Electronic configurations and oxidation states","pause_after_s":2.5},{"id":"s1l1","style":"curious","visual":"PART 1/8 · te.electron-configuration · objective: Write the electronic configuration of the first transition series. [CORE] Segment card (from t1's camera move): YK.actCard({num:'PART 1 OF 8', title:'Electronic configuration of the first transition series', size:100}) (E8 84–110; the kit default 130 is too big) + objective YK.text Cairo 600 40 textDim centred ~170 px under the title. ALL eight PART cards use this exact spec. Card collapses into the segment YK.chip (x 96, y 64, map title_en, never cut) on line start, chip kept to the micro-recap (s1l12). Line: FB YK.periodicTable (maxH 820, hp dims all but period 4); the Ca cell gold on cue 'calcium'; Sc–Zn cells outlined violet; a cyan YK.dot with a '?' tag hovers over Sc on cue 'electron'. RE-HOOK.","tts_text":"بعد الـ calcium، كل عنصر بيزوّد electron… بيروح فين بالظبط؟","screen_text":"After ₂₀Ca: where does each new electron go?"},{"id":"s1l2","visual":"[CORE] TP. Text panel row 1 (YK.formula 56): '₂₀Ca: [Ar] 4s²' builds on cues 'argon', 'four'. Stage: THE episode model (pedagogy rule 5): one 4s box + five 3d boxes (YK.electronBoxes, same colours as video-short-te.electron-configuration); 4s gets ↑↓ (pink) on cue 'باتنين'; 3d boxes empty. Book p.8 point 1.","tts_text":"الـ calcium بعد الـ argon، قافل الـ four s باتنين.","screen_text":"₂₀Ca: [Ar] 4s²"},{"id":"s1l3","visual":"[CORE] TP. Row 2 '₂₁Sc: [Ar] 4s² 3d¹' — only '3d¹' highlighted gold (the [Ar] 4s² part is carried, dim). Stage: one ↑ flies into 3d box 1 on cue 'three'. Book table p.8.","tts_text":"في الـ scandium، الـ electron الجديد بيدخل الـ three d على طول.","screen_text":"₂₁Sc: 3d¹"},{"id":"s1l4","visual":"PREREQ atom.hund-rule [RECAP-PREREQ] TP (<= 8 s). Prereq YK.chip (link icon) 'Hund's rule and orbital-box diagrams' under the segment chip. Stage: same model as video-short-atom.hund-rule: 5 boxes, ↑ ×5 drop singly on cue 'singly', then one ↓ pairs on cue 'pairing'; reset at line end. Reference only.","tts_text":"فاكرين Hund's rule؟ الـ electrons بتدخل singly الأول، والـ pairing بعدين.","screen_text":"Hund's rule: singly first, then pairing"},{"id":"s1l5","visual":"[CORE] FB (shot change): 5 custom tiles Sc → Mn across the frame (~300 px each), a YK.electronBoxes 3d set under each (boxes:5, size 52, labelPos 'none'). Sets fill left → right: Sc 1, Ti 2, V 3, Mn 5 singles (YK.stagger 0.4 s from cue 'titanium' to cue 'manganese'). Cr tile shows a coral '?' instead of boxes (its anomaly is Part 2; NEVER draw Cr as 3d⁴ here, it is false per book). On cue 'خمسة' the Mn set (five ↑) gets a gold edge + label '₂₅Mn: 3d⁵' (YK.label 48). Book p.8 'by single electron in each orbital in sequence till manganese (3d⁵)'.","tts_text":"ومن الـ titanium لحد الـ manganese، كل orbital ياخد واحد، لحد خمسة.","screen_text":"Ti → Mn: one electron in each orbital → ₂₅Mn: 3d⁵"},{"id":"s1l6","visual":"[CORE] FB strip Fe → Zn (same tile + box model as s1l5). A ↓ joins box 1 under Fe on cue 'pairing', then Co (7), Ni (8) staggered toward cue 'zinc'; Zn set all ↑↓, label '₃₀Zn: 3d¹⁰'. Cu tile shows the coral '?' instead of boxes (Part 2; no 3d⁹ drawn). Book p.8 point 1.","tts_text":"بعد الـ manganese يبدأ الـ pairing، لحد الـ zinc بعشرة كاملين.","screen_text":"Then pairing → ₃₀Zn: 3d¹⁰"},{"id":"s1l7","visual":"[CORE] TP. WORKED EXAMPLE (book table row ₂₆Fe). Text panel header 'Worked example: ₂₆Fe' (Cairo 800 48) at line start; row 1 YK.formula 64 '₂₆Fe: [Ar]' with '[Ar]' on cue 'argon' and a small mono '18' tag under it on cue 'تمنتاشر'. Stage: YK.configStrip({el:'Fe', step:0}) = [Ar] core chip + empty 4s + 3d boxes; mono counter '26' above it on cue 'ستة'.","tts_text":"يلا نكتب الـ iron، ستة وعشرين: أول تمنتاشر نفس الـ argon بالظبط.","screen_text":"Worked example: ₂₆Fe = [Ar] (18) + …"},{"id":"s1l8","visual":"[CORE] TP. Row 1 completes to '₂₆Fe: [Ar] 4s² 3d⁶' (YK.formula 64): '4s²' on cue 'four', '3d⁶' on cue 'three' ('[Ar]' is already there from s1l7; this tts has no 'argon'). Stage: configStrip Fe step 0→2 from cue 'four', 2→8 from cue 'three' (Hund order); YK.rightMark mint at line end.","tts_text":"وبعدين الـ four s اتنين، والـ three d الستة الباقيين.","screen_text":"₂₆Fe: … 4s² 3d⁶"},{"id":"s1l9","visual":"[CORE] TP. MISCONCEPTION (te.electron-configuration #2). Small coral row '[Ar] 3d⁶' + YK.wrongMark on cue 'غلط', held < 2 s and drawn smaller than the correct row above, which re-pulses its 4s² in gold. (Misconception #1, early pairing, is refuted by the Hund recap and the Fe build.)","tts_text":"ناس كتير بتنسى الـ four s وتكتب الـ three d بس… غلط.","screen_text":"3d⁶ only, no 4s ✕"},{"id":"s1l10","visual":"[CORE] PAUSE-AND-PREDICT (new case: short used Ni, lesson used Fe/Co/V/Ni). FB (shot change): strip with only the Ti tile lit gold + empty 4s/3d boxes under it; YK.checkPause question in the top band; think ring from cueEnd through the 3 s pause.","tts_text":"طب الـ titanium، اتنين وعشرين… اكتبوا الـ electronic configuration بتاعه. وقّفوا ثانية وفكّروا. <long pause>","screen_text":"Write the electronic configuration of ₂₂Ti.","pause_after_s":3},{"id":"s1l11","visual":"[CORE] FB. Answer builds on cues 'argon', 'four', 'three': 4s ↑↓, 3d ↑ ↑ (two separate boxes, Hund) + YK.rightMark; answer slot '₂₂Ti: [Ar] 4s² 3d²'.","tts_text":"الإجابة: argon، والـ four s فيها اتنين، والـ three d اتنين.","screen_text":"₂₂Ti: [Ar] 4s² 3d² ✓"},{"id":"s1l12","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title: 'Electronic configuration of the first transition series', line: '3d: singly up to Mn, then pairing', formula: '[Ar] 4s² 3dⁿ', pulse: [{word:'singly', at: cue(s1l12,'singly')}, {word:'pairing', at: cue(s1l12,'pairing')}]}); the formula carries a small textDim tag 'except Cr, Cu' (anomaly caveat, book p.8 point 2). Stage: Sc → Zn strip with boxes.","tts_text":"الخلاصة: three d بتتملي singly لحد الـ manganese، والـ pairing بعده.","screen_text":"3d: singly up to Mn, then pairing"},{"id":"s1l13","visual":"[CORE] SO-WHAT · FB. Strip; Cr and Cu tiles flicker coral once on cue 'اتنين' (no labels yet). Segment chip out at line end. In the pause: camera push into Cr = PART 2 card.","tts_text":"بس فيه اتنين في الصف ده مش ماشيين على القاعدة… مين؟","screen_text":"Two elements break the pattern. Which?","pause_after_s":2.5},{"id":"s2l1","visual":"PART 2/8 · te.cr-cu-anomaly · objective: Explain the abnormal electronic configuration of chromium and copper. [CORE] Segment card in s1l13's pause: YK.actCard({num: 'PART 2 OF 8', title: 'Abnormal electronic configuration of chromium and copper'}) + objective; chip kept to the micro-recap. Line: TP. Expected row '₂₄Cr: 4s² 3d⁴ ?' (textDim) builds on cues 'four', 'three'; stage: 4s ↑↓ + 3d ↑↑↑↑ (one box empty) in the episode model. RE-HOOK (misconception #1).","tts_text":"المفروض الـ chromium يبقى four s اتنين، و three d أربعة… بس لأ!","screen_text":"₂₄Cr: 4s² 3d⁴ ?"},{"id":"s2l2","visual":"[CORE] TP. Real row (gold) '₂₄Cr: [Ar] 4s¹ 3d⁵' under the expected row on cues 'argon', 'four', 'three'; stage: one ↓ lifts out of the 4s box on cue 'four' and arcs into the empty 3d box on cue 'three' (1.0 s), the expected row morphs into the real one. No energy diagram, no '4s lower' claim (G43). Book p.8 point 2 (episode's 4s-first order, like the book table).","tts_text":"الكتاب بيكتبه: argon، والـ four s واحد، والـ three d خمسة.","screen_text":"₂₄Cr: [Ar] 4s¹ 3d⁵"},{"id":"s2l3","visual":"[CORE] TP. NEW TERM 1 'anomalous' on its cue (Cairo 1000 64, gold). Stage keeps the 4s¹ 3d⁵ boxes. Book p.8 'anomalous from the expected electronic configuration'.","tts_text":"الكتاب بيسميه anomalous، يعني شاذ عن المتوقع.","screen_text":"Anomalous configuration"},{"id":"s2l4","visual":"[CORE] FB boxes. NEW TERM 2 'half-filled' (>= 1 s after term 1). The single 4s ↑ pulses on cue 'واحد'; label '4s¹: half-filled' (Cairo 800 44) on cue 'half-filled'.","tts_text":"ليه؟ الـ four s بقت half-filled، فيها electron واحد.","screen_text":"4s¹: half-filled"},{"id":"s2l5","visual":"[CORE] FB boxes. The five 3d ↑ light gold one by one on cue 'orbital' (0.15 s stagger); label '3d⁵: half-filled' on cue 'half-filled'.","tts_text":"والـ three d فيها خمسة، كل orbital فيه واحد… half-filled برضه.","screen_text":"3d⁵: half-filled"},{"id":"s2l6","visual":"[CORE] TP. NEW TERM 3 'extra stability'. The segment's one definition card YK.termCard({term: 'Extra stability', def: 'The atom has low energy when the outermost sublevel is half-filled (d⁵) or filled (d¹⁰).', keys: ['half-filled','filled']}) on cue 'stability'. Book p.9 wording. Atom-level claim only, nothing about 4s vs 3d energies (G43).","tts_text":"والـ atom كده طاقته أقل وأثبت، وده اسمه extra stability في الكتاب.","screen_text":"Low energy → extra stability"},{"id":"s2l7","visual":"[CORE] TP. Expected row '₂₉Cu: 4s² 3d⁹ ?' (textDim) on cues 'four', 'three'; stage: Cu boxes 4s ↑↓ + 3d with four pairs and one single.","tts_text":"الـ copper نفس الحكاية: المفروض four s اتنين، و three d تسعة.","screen_text":"₂₉Cu: 4s² 3d⁹ ?"},{"id":"s2l8","visual":"[CORE] FB boxes. One ↓ arcs from 4s into the last 3d box on cue 'four' (same arc move as Cr); real row '₂₉Cu: [Ar] 4s¹ 3d¹⁰' (gold) on cue 'three'. Book p.8.","tts_text":"بس الحقيقة: argon، والـ four s واحد، والـ three d عشرة.","screen_text":"₂₉Cu: [Ar] 4s¹ 3d¹⁰"},{"id":"s2l9","visual":"[CORE] FB boxes. Label '4s¹: half-filled' on cue 'half-filled', '3d¹⁰: filled' on YK.cue('s2l9','filled',1) (needle 'filled' hits 'half-filled' first) (all ten 3d arrows glow). Book p.9 'in copper 4s is half filled but 3d is filled'.","tts_text":"كده الـ four s تبقى half-filled، والـ three d تبقى filled خالص.","screen_text":"4s¹: half-filled · 3d¹⁰: filled"},{"id":"s2l10","visual":"[TRIM-IF-OVER 15:00 after narration; 1st to cut] TP. Small note card (Cairo 600 36, textDim) in the book's wording 'But this is not the only main factor that causes the stability of the atom' (book p.9).","tts_text":"بس الكتاب بينبّه: ده مش العامل الوحيد للثبات.","screen_text":"Not the only factor for stability"},{"id":"s2l11","visual":"[CORE] PAUSE-AND-PREDICT (NEW case for the promotion rule; refutes misconception #2 'other elements also promote, e.g. Fe 4s¹ 3d⁷'). [TTS FIX PENDING] FB split-screen, first-mentioned on the left: Fe (left) YK.configStrip({el:'Fe'}) 4s² 3d⁶ with a dashed coral ghost arc from 4s to the 3d pair box and a '?' on cue 'iron' | Cr (right, done, dimmed 60%) configStrip Cr 4s¹ 3d⁵ on cue 'chromium'. YK.checkPause question in the text band top-left; think ring from cueEnd through the 3 s pause.","tts_text":"طب الـ iron، هينقل electron للـ three d زي الـ chromium؟ وقّفوا وفكّروا. <long pause>","screen_text":"₂₆Fe: move a 4s electron into 3d, like Cr?","pause_after_s":3},{"id":"s2l12","visual":"[CORE] FB split left panel. On cue 'three': ghost result drawn small under Fe (YK.electronBoxes, coral, alpha 0.6): 4s ↑ + 3d ↑↓ ↑↓ ↑ ↑ ↑ with label '4s¹ 3d⁷' → tags 'not half-filled' / 'not filled' pop on cues 'half-filled' and YK.cue('s2l12','filled',1) ('filled' alone hits 'half-filled' first), then YK.wrongMark on the ghost on cue 'extra' (< 2 s, smaller than the correct row). The real Fe strip pulses + answer slot '₂₆Fe: [Ar] 4s² 3d⁶' + YK.rightMark. Book table p.8 (only Cr and Cu are anomalous).","tts_text":"لأ: كده three d سبعة، لا half-filled ولا filled، فمفيش extra stability هنا.","screen_text":"No: 3d⁷ is neither half-filled nor filled → ₂₆Fe: [Ar] 4s² 3d⁶ ✓"},{"id":"s2l13","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title: 'Abnormal electronic configuration of chromium and copper', line: 'Half-filled or filled → extra stability', formula: 'Cr: [Ar] 4s¹ 3d⁵ · Cu: [Ar] 4s¹ 3d¹⁰', pulse on 'Half-filled', 'filled' (YK.cue('s2l13','filled',1)), 'stability' at their cues}).","tts_text":"الخلاصة: half-filled أو filled… ده extra stability للـ atom كله.","screen_text":"Half-filled or filled → extra stability"},{"id":"s2l14","visual":"[CORE] SO-WHAT · FB. The Fe boxes from Part 1 return; two electrons wobble (4s pair and the 3d pair both glow, undecided) on cue 'electrons'; label 'Atom → ion' on cue 'ion'. Chip out. Camera move into the PART 3 card in the pause.","tts_text":"طب لما الـ atom يخسر electrons ويبقى ion، مين يمشي الأول؟","screen_text":"Atom → ion: which electrons leave first?","pause_after_s":2.5},{"id":"s3l1","visual":"PART 3/8 · te.ion-configuration · objective: Write the electronic configuration of the ions of the first transition series. [CORE] Segment card in s2l14's pause (YK.actCard 'PART 3 OF 8', 'Ions: 4s electrons are lost first' + objective); chip kept to the micro-recap. Line: TP; Fe boxes (4s ↑↓, 3d ↑↓↑↑↑↑), two arrows '?' over 4s and over the 3d pair on cue 'sublevel'. RE-HOOK.","tts_text":"الـ iron هيخسر اتنين electrons… من أنهي sublevel بالظبط؟","screen_text":"Fe → Fe²⁺: which 2 electrons leave?"},{"id":"s3l2","visual":"PREREQ chem.ions [RECAP-PREREQ] TP (<= 6 s). Prereq chip 'Ions (cations and anions)' (link icon). Stage: same model as video-short-chem.ions: neutral atom glyph loses two dots on cue 'electrons' and gets a '2+' badge on cue 'ion'. Reference only.","tts_text":"فاكرين؟ الـ atom لما يخسر electrons بيبقى ion موجب.","screen_text":"Atom − electrons → ion (+)"},{"id":"s3l3","visual":"[CORE] TP. MISCONCEPTION (te.ion-configuration #1). Coral text 'Last in = first out?'; stage: the 3d pair (last filled) starts to leave in coral, stopped by YK.wrongMark at line end (< 2 s, smaller than the correction).","tts_text":"ناس كتير فاكرة إن آخر electron دخل، هو أول واحد يطلع.","screen_text":"Last electron in = first out? ✕"},{"id":"s3l4","visual":"[CORE] FB (shot change): YK.atom({Z:26, size 380, rotate:0, highlightShell:3}) at stage centre = shells 2, 8, 14, 2; the n = 4 shell (its two electrons) gold, label 'outer level (n = 4)' (YK.label 44) on cue 'outer'; label '3d is in n = 3' small textDim on the third shell. On cue 'بتطلع': redraw with shells [2, 8, 14, 0] while two YK.dot electrons fly off right from the outer shell (YK.flyer-free: tween x/y, cyan trail). G43/E4b wording only: 'outer level', never 'lower in energy'. Book p.9 point 3.","tts_text":"غلط. الـ four s هي الـ outer level، فإلكتروناتها بتطلع الأول.","screen_text":"4s: the outer level → its electrons leave first ✓"},{"id":"s3l5","visual":"[CORE] TP. Stage: the 4s ↑↓ fly off right on cue 'four' (4s box shows '0'); 3d unchanged. Row 2 '− 4s²' (coral strike).","tts_text":"يخسر الاتنين بتوع الـ four s، والـ three d تفضل زي ما هي.","screen_text":"4s² leaves first → 4s⁰"},{"id":"s3l6","visual":"[CORE] TP. Row 3 'Fe²⁺: [Ar] 3d⁶' (gold) on cue 'iron'. Same 3d boxes as the atom: 'same 3d as the atom' contrast (pedagogy #1).","tts_text":"يبقى الـ iron two فيه argon، والـ three d ستة.","screen_text":"Fe²⁺: [Ar] 3d⁶"},{"id":"s3l7","visual":"[CORE] FB (shot change, boxes large). The ↓ of the 3d pair leaves on cue 'three'; five singles remain; label 'Fe³⁺: [Ar] 3d⁵' on cue 'iron'. (Its stability is Part 4; not mentioned here.) Book p.9.","tts_text":"ولو خسر واحد كمان من الـ three d، يبقى الـ iron three بخمسة.","screen_text":"Fe³⁺: 3d⁵"},{"id":"s3l8","visual":"[CORE] FB: the 10-tile strip (cold-open model). '2+' badges pop on Ti → Zn left → right, YK.stagger(gap 0.25) from cue 'ion' (one idea: every tile gets 2+; no per-tile electron flicks). Sc tile greys with a '3+ only' tag on cue 'scandium'. Book p.9 point 3 + table (Sc: 3).","tts_text":"وكل عناصر الصف بتعمل ion اتنين موجب كده، إلا الـ scandium لوحده.","screen_text":"All form 2+ ions (except Sc)"},{"id":"s3l9","visual":"[CORE] TP. Cr boxes from Part 2 return (same model, same colours): 4s ↑, 3d ↑ ×5; row '₂₄Cr: 4s¹ 3d⁵'.","tts_text":"الـ chromium، فاكرينه؟ four s واحد، و three d خمسة.","screen_text":"₂₄Cr: 4s¹ 3d⁵"},{"id":"s3l10","visual":"[CORE] PAUSE-AND-PREDICT (new case: lesson used Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺; tests 4s-first on an anomalous atom, misconception #23). TP: YK.checkPause 'Cr³⁺: how many 3d electrons?'; stage: Cr boxes, think ring through the 3 s pause.","tts_text":"طب الـ chromium three، الـ three d فيها كام؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"Cr³⁺: how many 3d electrons?","pause_after_s":3},{"id":"s3l11","visual":"[CORE] FB (shot change, avoids a 4th text-panel shot in a row): Cr strip large at stage centre (YK.configStrip({el:'Cr', charge:3, remove})): 4s ↑ leaves on cue 'four', then two 3d ↑ leave on cue 'three' → three singles; answer slot 'Cr³⁺: [Ar] 3d³' (YK.formula 64) top-left + YK.rightMark.","tts_text":"تلاتة: الـ four s الأول، وبعدها اتنين من الـ three d كمان.","screen_text":"Cr³⁺: 3d³ ✓ (4s first, then 3d)"},{"id":"s3l12","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title: 'Ions: 4s electrons are lost first', line: 'Ions: 4s electrons are lost first, then 3d', formula: 'Fe²⁺: [Ar] 3d⁶ · Fe³⁺: [Ar] 3d⁵', pulse on '4s' at cue 'four' and '3d' at cue 'three'}).","tts_text":"الخلاصة: في الـ ions، الـ four s بتطلع الأول، وبعدين الـ three d بالترتيب.","screen_text":"Ions: 4s electrons are lost first, then 3d"},{"id":"s3l13","visual":"[CORE] SO-WHAT · FB. Camera pulls back from the boxes to the empty recap row (match cut into m1). Chip out.","tts_text":"خلّينا نلم اللي فات قبل ما نكمّل.","screen_text":"So far: three steps"},{"id":"m1l1","visual":"[CORE] MID-EPISODE RECAP 1 (~4:55) · FB. YK.flow({rtl:false, layout:'row', area:{x:96,y:380,w:1728,h:320}, node:{size:40}}); header 'So far' (Cairo 800 40) top-left. Node 1 '3d: singly, then pairing' (5-box glyph) on cue 'singly'.","tts_text":"الـ three d بتتملي singly لحد الـ manganese، والـ pairing بعده.","screen_text":"3d: singly, then pairing"},{"id":"m1l2","visual":"[CORE] FB flow: arrow + node 2 'Cr, Cu: half-filled / filled' on cue 'chromium'.","tts_text":"الـ chromium والـ copper شذّوا، عشان الـ half-filled والـ filled أثبت.","screen_text":"Cr, Cu: half-filled / filled"},{"id":"m1l3","visual":"[CORE] FB flow: arrow + node 3 'Ions: 4s lost first' on cue 'four'; nodes 1-3 glow once together. In the pause: camera moves from node 3 to the Fe²⁺ boxes = PART 4 card.","tts_text":"وفي الـ ions، الـ four s بتطلع الأول.","screen_text":"Ions: 4s lost first","pause_after_s":2.5},{"id":"s4l1","style":"curious","visual":"PART 4/8 · te.fe2-fe3-mn2-stability · objective: Explain why iron (II) is easily oxidized to iron (III) whereas Mn (II) is not. [CORE] Segment card in m1l3's pause (PART card spec from s1l1: 'PART 4 OF 8', 'Iron(II) is easily oxidized while manganese(II) is not' + objective); chip kept to the micro-recap. [TTS FIX PENDING] Line: FB, Fe²⁺ YK.configStrip({el:'Fe', charge:2}) large; on cue 'electron' the paired ↓ wobbles; on cue 'بسهولة' a fast green arrow 'Fe²⁺ → Fe³⁺' snaps across; '?' on cue 'ليه'. Mn is NOT shown or said here: its answer is the s4l8 predict. RE-HOOK (book exercise p.9).","tts_text":"الـ iron two بيخسر electron كمان بسهولة ويبقى iron three… ليه؟","screen_text":"Fe²⁺ → Fe³⁺: easily. Why?"},{"id":"s4l2","visual":"PREREQ redox.electronic [RECAP-PREREQ] TP (<= 6 s). Prereq chip 'Oxidation and reduction by electrons' (link icon). Stage: same model as video-short-redox.electronic: one electron leaves an ion glyph on cue 'electrons', charge badge +1. Reference only.","tts_text":"فاكرين؟ الـ oxidation يعني الـ ion يخسر electrons كمان.","screen_text":"Oxidation: loss of electrons"},{"id":"s4l3","visual":"[CORE] TP. WORKED (book p.9 solution + figure): Fe²⁺ boxes (from Part 3), row 'Fe²⁺: [Ar] 3d⁶' on cue 'three'.","tts_text":"الـ iron two، زي ما شفنا: three d فيها ستة.","screen_text":"Fe²⁺: 3d⁶"},{"id":"s4l4","visual":"[CORE] FB (shot change; book figure re-drawn large): Fe²⁺ boxes → arrow labelled 'Oxidation' → Fe³⁺ boxes; the paired ↓ leaves on cue 'electron'; label 'Fe³⁺: [Ar] 3d⁵' on cue 'iron'.","tts_text":"لو خسر الـ electron ده، يبقى الـ iron three، والـ three d خمسة.","screen_text":"Fe³⁺: 3d⁵"},{"id":"s4l5","visual":"[CORE] FB. Fe³⁺ boxes get the gold 'half-filled (d⁵) more stable' tag (book figure label) on cue 'half-filled'; the 'Oxidation' arrow thickens on cue 'بسهولة'. Book: 'the reaction goes toward the formation of the more stable compound'.","tts_text":"والـ three d خمسة يعني half-filled، أثبت، فالتفاعل بيروح ناحيته بسهولة.","screen_text":"3d⁵ half-filled → more stable ✓"},{"id":"s4l6","visual":"[CORE] TP. MISCONCEPTION (te.fe2-fe3-mn2-stability #2). Coral '3+ > 2+ ?' + YK.wrongMark on cue 'أكبر' (< 2 s), then gold 'half-filled' + YK.rightMark on cue 'half-filled'.","tts_text":"مش عشان شحنة الـ iron three أكبر… السبب الـ half-filled نفسه.","screen_text":"Bigger charge ✕ · half-filled ✓"},{"id":"s4l7","visual":"[CORE] TP. Mn boxes (from Part 2) on the right half of the stage; row '₂₅Mn: 4s² 3d⁵'.","tts_text":"والـ manganese؟ الـ four s اتنين، والـ three d خمسة.","screen_text":"₂₅Mn: 4s² 3d⁵"},{"id":"s4l8","visual":"[CORE] PAUSE-AND-PREDICT (predict before the book's second case is shown; the lesson asked 'which one is easily oxidized' on both together). FB split: Fe²⁺ → Fe³⁺ (left, done, ✓) | Mn²⁺ → ? (right). YK.checkPause; think ring through the 3 s pause.","tts_text":"طب الـ manganese two: هيتأكسد بسهولة لـ manganese three؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"Mn²⁺ → Mn³⁺: easily? Yes or no?","pause_after_s":3},{"id":"s4l9","visual":"[CORE] FB split right panel: Mn 4s ↑↓ leave on cue 'four'; five 3d singles stay; label 'Mn²⁺: [Ar] 3d⁵' + gold 'half-filled (d⁵) more stable' tag (book figure); then the book's second figure: dashed coral 'Oxidation' arrow to Mn³⁺ boxes (3d⁴, one empty box) fades in small, crossed; 'No' + YK.rightMark. Book p.9: Mn²⁺ more stable than Mn³⁺, not readily oxidized.","tts_text":"لأ. الـ manganese two بيخسر الـ four s بس، فالـ three d خمسة.","screen_text":"No: Mn²⁺ is 3d⁵ ✓"},{"id":"s4l10","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title: 'Iron(II) is easily oxidized while manganese(II) is not', line: 'Fe²⁺ → Fe³⁺: reaches half-filled · Mn²⁺: already half-filled', formula: 'Fe³⁺: 3d⁵ · Mn²⁺: 3d⁵', pulse 'half-filled' at both cues}).","tts_text":"الخلاصة: الـ iron two بيجري على الـ half-filled، والـ manganese two قاعد فيه أصلاً.","screen_text":"Fe²⁺ → Fe³⁺: reaches half-filled · Mn²⁺: already half-filled"},{"id":"s4l11","visual":"[CORE] SO-WHAT · FB. Fe tile shows '2+ 3+' badges at line start; camera pulls back (1.2 s) to the 10-tile strip, each tile gets a blank '?' badge staggered from cue 'scandium' to cue 'zinc'. Chip out. PART 5 card in the pause.","tts_text":"طب من الـ scandium للـ zinc، كل واحد يوصل لكام؟","screen_text":"Sc → Zn: how far can each go?","pause_after_s":2.5},{"id":"s5l1","style":"curious","visual":"PART 5/8 · te.oxidation-states-trend · objective: Describe how the oxidation states change from scandium to zinc. [CORE] Segment card in s4l11's pause ('PART 5 OF 8', 'Oxidation states from Sc to Zn' + objective); chip kept to the micro-recap. Line: FB strip, Mn badge '+7' (gold) on cue 'manganese', Zn badge '+2' on cue 'zinc' (callback to the cold open). RE-HOOK.","tts_text":"الـ manganese بيوصل لسبعة… والـ zinc جنبه بيقف عند اتنين. إزاي؟","screen_text":"Mn: +7 · Zn: only +2. How?"},{"id":"s5l2","visual":"PREREQ pt.oxidation-number [RECAP-PREREQ] TP (<= 8 s). Prereq chip 'Oxidation state in compounds' (link icon). Text panel: the line as a short rule (YK.para 44, key 'in a compound'). Stage: same model as video-short-pt.oxidation-number (a compound with a charge tag over each element). Reference only.","tts_text":"فاكرين الـ oxidation state؟ الشحنة اللي العنصر بياخدها جوه المركّب.","screen_text":"Oxidation state: the charge an element has in a compound"},{"id":"s5l3","visual":"[CORE] TP. WORKED EXAMPLE (book table compound KMnO₄). Stage: 'KMnO₄' YK.formula 120 with the name label 'potassium permanganate' (Cairo 800 40) under it on cue 'potassium' (1st occurrence = the name). Text panel rows (YK.formula 52) build: 'K: +1' on YK.cue('s5l3','potassium',1) (2nd occurrence), '4 O: 4 × (−2) = −8' on 'oxygen', '(+1) + Mn + (−8) = 0 → Mn = +7' with +7 gold on 'manganese'; charge tags drop onto K, O, Mn in the stage formula on the same cues.","tts_text":"في الـ potassium permanganate: الـ potassium واحد، والـ oxygen سالب تمانية… فالـ manganese سبعة.","screen_text":"KMnO₄: (+1) + Mn + 4(−2) = 0 → Mn = +7"},{"id":"s5l4","visual":"[CORE] FB (shot change). YK.oxStates (book table p.8, all states as violet dots + gold max line) in two calls with identical size and column width so the build can stop at Mn: call A data series1.slice(0,5) (Sc → Mn), grow 0→1 from cue 'scandium' to cue 'سبعة', title 'Oxidation states' (top-left). Mn max dot pulses on 'سبعة' (highlight ['Mn']). Sc column tag '+3 only' small. Trap: one call with grow staggers all 10 columns. Book p.9 point 4.","tts_text":"من الـ scandium للـ manganese، أعلى oxidation state بيزيد، لحد سبعة.","screen_text":"Sc → Mn: highest oxidation state rises to +7"},{"id":"s5l5","visual":"[CORE] FB plot: call B data series1.slice(5) (Fe → Zn) to the right of call A, grow from cue 'بيقل' to cue 'zinc'; a gold connector joins Mn's max dot to Fe's on 'بيقل' (the two calls each draw their own max line). Whole profile reads rise-then-fall; Zn's +2 gold on 'zinc'. Book table values (Cu: +1, +2).","tts_text":"بعد الـ manganese، الأعلى بيقل تدريجياً، لحد الـ zinc، اتنين بس.","screen_text":"After Mn: decreases gradually → Zn: +2"},{"id":"s5l6","visual":"[CORE] TP. Fe column of the plot stays on stage, highlighted; text panel: coral '+8 ?' + YK.wrongMark on cue 'مبيوصلش' (< 2 s); Fe row '2, 3, 6' (mono 52) on cue 'ستة'; '2, 3' gold on cue 'المهمين'; note 'above +3: not important' textDim (book iron section: 'All the oxidation states above (+3) are not important').","tts_text":"والـ iron؟ مبيوصلش لتمانية: أعلاه ستة، والمهمين اتنين وتلاتة بس.","screen_text":"Fe: not +8 ✕ · 2, 3, 6 (states above +3 not important)"},{"id":"s5l7","visual":"[CORE] FB (shot change: plot fills the frame). Book group labels under the symbols (IIIB … VIIB, VIII ×3, IB, IIB; YK.GROUPS_BOOK) appear on cue 'group'; a short dashed gold tick per column at the group number (py(n) from oxStates' return; VIII = 8 sits just above the +7 row) staggered on the same cue. Sc → Mn max dots touch their tick; VIII columns stay below (refutes 'max always = group number'). Book p.9 point 4.","tts_text":"والقاعدة: أعلى oxidation state مبيعديش رقم الـ group بتاعته.","screen_text":"Highest oxidation state does not exceed the group number"},{"id":"s5l8","visual":"[CORE] FB plot: Cu's max dot (+2) glows gold above its IB tick (= 1) on cue 'copper'; small custom tiles 'Ag', 'Au' slide in beside Cu on cues 'silver', 'gold' (they are not in the plot). Book p.9.","tts_text":"إلا group الـ copper والـ silver والـ gold، بيعدّوا الرقم ده.","screen_text":"Except Cu, Ag, Au (group IB)"},{"id":"s5l9","visual":"[CORE] PAUSE-AND-PREDICT (new case: lesson used Mo and Au). TP: YK.checkPause; stage: a column glyph of group VIIB (Mn on top, Re under it, both labelled by name: 'manganese', 'rhenium'). Think ring through the 3 s pause.","tts_text":"الـ rhenium في group سبعة، زي الـ manganese. أعلى oxidation state كام؟ وقّفوا وفكّروا. <long pause>","screen_text":"Re is in group VIIB, like Mn. Highest oxidation state?","pause_after_s":3},{"id":"s5l10","visual":"[CORE] TP. Answer '+7 at most' + YK.rightMark on cue 'سبعة'; the dashed group line at 7 glows on cue 'group'.","tts_text":"سبعة، ومبيعديهاش، عشان رقم الـ group بتاعه سبعة.","screen_text":"+7 at most (= group number) ✓"},{"id":"s5l11","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title: 'Oxidation states from Sc to Zn', line: 'Up to +7 at Mn, down to +2 at Zn', pulse '+7' at cue 'سبعة', '+2' at cue 'اتنين'}); stage: the rise-and-fall chart small.","tts_text":"الخلاصة: بيطلع لحد سبعة في الـ manganese، وينزل لحد الـ zinc عند اتنين.","screen_text":"Up to +7 at Mn, down to +2 at Zn"},{"id":"s5l12","visual":"[CORE] SO-WHAT · FB. Back to the oxStates plot: V's four dots (+2 … +5) pulse one by one on cue 'كتير' (all states were already dots; the max line dims); headline 'Why several?' top-left. Chip out. PART 6 card in the pause.","tts_text":"طب ليه عندهم oxidation states كتير أصلاً، مش واحدة بس؟","screen_text":"Why several oxidation states?","pause_after_s":2.5},{"id":"s6l1","style":"curious","visual":"PART 6/8 · te.multiple-oxidation-states · objective: Explain why transition elements have several oxidation states. [CORE] Segment card in s5l12's pause ('PART 6 OF 8', 'Why several oxidation states' + objective); chip kept to the micro-recap. Line: split-screen (first-mentioned Na left): Na loses one dot and stops ('+1'); V loses dots one by one to '+5'. RE-HOOK. Book p.10 point 5 (representative metals: one oxidation state).","tts_text":"الـ sodium بيقف عند electron واحد… والـ vanadium يوصل لخمسة. ليه؟","screen_text":"Na: +1 only · V: up to +5. Why?"},{"id":"s6l2","visual":"PREREQ pt.ionization-energy [RECAP-PREREQ] TP (<= 10 s). Prereq chip 'Ionization energy' (link icon). Stage: same model as video-short-pt.ionization-energy (a staircase of removal costs); Na's steps show one small step then a huge one. Reference only.","tts_text":"فاكرين الـ ionization energy؟ طاقة شيل electron، وكل واحد بعده أغلى.","screen_text":"Ionization energy: energy needed to remove an electron"},{"id":"s6l3","visual":"[CORE] FB (shot change). NEW TERM 1 'close in energy' (book p.10 wording). The 4s box and the five 3d boxes slide close together, side by side, on cue 'قريبين'; label '4s and 3d: close in energy'. No claim that one is lower (G43).","tts_text":"هنا الـ four s والـ three d قريبين في الطاقة.","screen_text":"4s and 3d: close in energy"},{"id":"s6l4","visual":"[CORE] FB. WORKED EXAMPLE (book flowchart p.10). Full-bleed YK.stairs({values:[648,1346,2858,4643,6523], species:['V','V^+','V^2+','V^3+','V^4+','V^5+'], title:'Ionization energies of vanadium', unit:'kJ/mol'}) x 96–1824, y 200–860, step 0 (only the 'V' tread). Under it one config row (YK.formula 52, x 96) that always shows the current species in the book's flowchart notation: 'V: 4s² 3d³' with '4s²' on cue 'four', '3d³' on cue 'three'.","tts_text":"خلّينا نشوف الـ vanadium، فيه four s اتنين، و three d تلاتة.","screen_text":"V: 4s² 3d³"},{"id":"s6l5","visual":"[CORE] FB stairs: step 0→1 from cue 'ستمية' (the kit shows '648' only once the tread is ≥ 60% up); config row morphs to 'V⁺: 4s¹ 3d³'.","tts_text":"أول electron من الـ four s: ستمية تمانية وأربعين.","screen_text":"V → V⁺: 648 kJ/mol"},{"id":"s6l6","visual":"[CORE] FB stairs: step 1→2 from cue 'ألف'; config row 'V²⁺: 4s⁰ 3d³' (4s⁰ written, book notation).","tts_text":"والتاني من الـ four s كمان: ألف تلتمية ستة وأربعين.","screen_text":"V⁺ → V²⁺: 1346 kJ/mol (4s⁰ 3d³)"},{"id":"s6l7","visual":"[CORE] FB stairs: step 2→3 from cue 'ألفين' (needle is unique in this line); config row 'V³⁺: 4s⁰ 3d²'.","tts_text":"والتالت من الـ three d: ألفين تمنمية تمانية وخمسين.","screen_text":"V²⁺ → V³⁺: 2858 kJ/mol"},{"id":"s6l8","visual":"[CORE] FB stairs: step 3→4 on cue 'أربعة', 4→5 on cue 'ستة'; config row 'V⁴⁺: 4s⁰ 3d¹' then 'V⁵⁺: 4s⁰ 3d⁰'. At line end small state chips '+2 +3 +4 +5' over treads 2–5 (book table V: 2, 3, 4, 5).","tts_text":"وبعدها أربعة آلاف ستمية تلاتة وأربعين، وستة آلاف خمسمية تلاتة وعشرين.","screen_text":"4643 → 6523 kJ/mol (V⁵⁺: 4s⁰ 3d⁰)"},{"id":"s6l9","visual":"[CORE] TP + stairs kept small on the stage. MISCONCEPTION (te.multiple-oxidation-states #1). A coral dashed ghost cliff after tread 2 + YK.wrongMark on cue 'مفيش' (< 2 s); then the real treads 1–5 glow gold with a smooth trend line on cue 'تدريجية'; text panel 'Huge jump after 4s? ✕' / 'Gradual rise ✓'. Book p.10 'increases gradually'.","tts_text":"يعني مفيش قفزة ضخمة بعد الـ four s، الزيادة تدريجية.","screen_text":"A huge jump after 4s? ✕ Gradual rise ✓"},{"id":"s6l10","visual":"[CORE] PAUSE-AND-PREDICT (new case: lesson used V and metals X/Y). TP: YK.checkPause '₂₂Ti: one oxidation state, or several?'; stage: Ti boxes (4s ↑↓, 3d ↑ ↑). Think ring through the 3 s pause.","tts_text":"والـ titanium؟ ليه oxidation state واحدة، ولا كذا واحدة؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"₂₂Ti: one oxidation state, or several?","pause_after_s":3},{"id":"s6l11","visual":"[CORE] FB (shot change, avoids a 4th text-panel shot in a row): Ti column from the oxStates plot large at stage centre (model reuse): its dots +2, +3, +4 pop on cue 'اتنين'; Ti configStrip (4s² 3d²) beside it with the 4s and 3d boxes drawn close together, tag '4s, 3d close in energy' on cue 'قريبين'; answer slot top-left 'Several: +2, +3, +4' + YK.rightMark.","tts_text":"كذا حالة: اتنين وتلاتة وأربعة، عشان الـ four s والـ three d قريبين.","screen_text":"Several: +2, +3, +4 ✓"},{"id":"s6l12","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title: 'Why several oxidation states', line: '4s and 3d close in energy → several oxidation states', pulse 'close' at cue 'قريبين', 'several' at cue 'كتير'}); stage: the vanadium ramp small.","tts_text":"الخلاصة: الـ four s والـ three d قريبين، فيبقى فيه oxidation states كتير.","screen_text":"4s and 3d close in energy → several oxidation states"},{"id":"s6l13","visual":"[CORE] SO-WHAT · FB. The 10-tile strip returns; a gold label 'transition element' hovers over it and blinks on cue 'transition'. Chip out. Match cut into m2 (no pause).","tts_text":"طب مين بالظبط اللي يستاهل اسم transition element أصلاً؟","screen_text":"Who deserves the name 'transition element'?"},{"id":"m2l1","visual":"[CORE] MID-EPISODE RECAP 2 (~9:10) · FB. YK.flow({rtl:false}) row continues the m1 chain (nodes 1-3 small, dim, on the left); header 'So far'. Node 4 'Fe²⁺ → Fe³⁺: half-filled' on cue 'iron'.","tts_text":"نلم تاني: الـ iron two بيتأكسد بسهولة، عشان الـ half-filled أثبت.","screen_text":"Fe²⁺ → Fe³⁺: half-filled"},{"id":"m2l2","visual":"[CORE] FB flow: arrow + node 5 'Up to +7 at Mn' (mini rise-fall glyph) on cue 'سبعة'.","tts_text":"والـ oxidation states بتطلع لحد سبعة في الـ manganese، وبتنزل بعده.","screen_text":"Up to +7 at Mn"},{"id":"m2l3","visual":"[CORE] FB flow: arrow + node 6 '4s, 3d close in energy' on cue 'قريبين'; nodes 1-6 glow once. In the pause: camera move into the PART 7 card.","tts_text":"وهي كتير عشان الـ four s والـ three d قريبين في الطاقة.","screen_text":"4s, 3d close in energy","pause_after_s":2.5},{"id":"s7l1","style":"curious","visual":"PART 7/8 · te.definition · objective: Define the transition element and apply it to scandium. [CORE] Segment card in m2l3's pause ('PART 7 OF 8', 'Definition of the transition element' + objective); chip kept to the micro-recap. Line: TP; Sc³⁺ boxes all empty, label 'Sc³⁺: 3d⁰' on cue 'three'; '?' on cue 'transition'. RE-HOOK (misconception #2/#21).","tts_text":"الـ scandium three، الـ three d فاضية خالص… يفضل transition element ولا لأ؟","screen_text":"Sc³⁺: 3d⁰. Still a transition element?"},{"id":"s7l2","visual":"[CORE] TP. NEW TERM (the segment's one definition card, built in 2 lines). YK.termCard({term: 'The transition element', def: 'The element in which the orbitals of d or f contain electrons but they are not complete in their atomic state or in one of their oxidation states.', keys: ['not complete','atomic state','oxidation states']}) first half on cue 'transition'. Stage: d boxes with some electrons on cue 'electrons'. Book p.10 exact wording.","tts_text":"الـ transition element: الـ d orbitals أو الـ f orbitals فيها electrons، بس…","screen_text":"Transition element: d or f orbitals contain electrons…"},{"id":"s7l3","visual":"[CORE] TP. Card second half; keys gold on cues 'complete', 'atomic', 'oxidation'. Stage: two slots 'atom' | 'ion' light in turn.","tts_text":"مش complete، في الـ atomic state، أو في واحدة من الـ oxidation states بتاعته.","screen_text":"… not complete in the atomic state or in one of its oxidation states"},{"id":"s7l4","visual":"[CORE] FB (shot change). Two-gate diagram LTR: gate 1 'Test 1: the atom' on cue 'atom', gate 2 'Test 2: its ions' on cue 'ions'; an element token can pass at either gate (pass = transition element).","tts_text":"يعني اختبارين: الـ atom الأول، وبعدين الـ ions بتوعه.","screen_text":"Test 1: the atom · Test 2: its ions"},{"id":"s7l5","visual":"[CORE] FB gate diagram: WORKED (book definition applied to Sc; Sc is transition, pedagogy #21). Sc token at gate 1 shows boxes '3d¹' on cue 'three'.","tts_text":"نطبّق على الـ scandium: الـ atom فيه three d واحد.","screen_text":"₂₁Sc atom: 3d¹"},{"id":"s7l6","visual":"[CORE] FB: gate 1 opens green on cue 'complete'; Sc passes, stamped 'transition element ✓' on cue 'transition'.","tts_text":"فيه electrons ومش complete… يبقى transition element من أول اختبار.","screen_text":"Contains electrons, not complete → transition element ✓"},{"id":"s7l7","visual":"[CORE] TP. The hook's Sc³⁺ empty boxes return small, greyed, with 'one test is enough' on cue 'كفاية' (answers the re-hook).","tts_text":"ومش مهم إن الـ scandium three فاضي، اختبار واحد كفاية.","screen_text":"Sc³⁺ (3d⁰) doesn't matter: one test is enough"},{"id":"s7l8","visual":"[CORE] TP. Case setup (V₂O₅ is familiar from te-uses; V⁵⁺ is the stairs' last tread): 'V₂O₅' YK.formula 96 + name label 'vanadium pentoxide' (Cairo 800 40) on cue 'vanadium'; 'V: +5, 3d⁰' on cue 'three'; stage: V⁵⁺ configStrip (charge 5) with empty boxes.","tts_text":"في الـ vanadium pentoxide، الـ vanadium بيبقى three d صفر.","screen_text":"V₂O₅: V is +5, 3d⁰"},{"id":"s7l9","visual":"[CORE] PAUSE-AND-PREDICT (new case: lesson used Sc, Mn, Ti/TiO₂). FB gate diagram with the V token waiting before gate 1; YK.checkPause; think ring through the 3 s pause.","tts_text":"الـ vanadium يفضل transition element ولا لأ؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"Is vanadium still a transition element?","pause_after_s":3},{"id":"s7l10","visual":"[CORE] FB: V token shows atom boxes '3d³' on cue 'three', passes gate 1 + YK.rightMark.","tts_text":"أيوه، الـ atom نفسه three d تلاتة، واختبار واحد كفاية.","screen_text":"Yes: the V atom is 3d³ ✓"},{"id":"s7l11","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title: 'Definition of the transition element', line: 'Incomplete d orbitals: in the atom or in one oxidation state', pulse 'atom' at cue 'atom', 'oxidation state' at cue 'oxidation'}).","tts_text":"الخلاصة: الـ d orbitals ناقصة في الـ atom، أو في oxidation state واحدة.","screen_text":"Incomplete d orbitals: in the atom or in one oxidation state"},{"id":"s7l12","visual":"[CORE] SO-WHAT · FB gate diagram; Cu and Zn tokens arrive at gate 1 with '3d¹⁰' boxes, both bounce (atom complete) on cue 'عشرة'. Chip out. PART 8 card in the pause.","tts_text":"طب والـ copper والـ zinc، اللي الـ atom بتاعهم three d عشرة؟","screen_text":"Cu and Zn: atom 3d¹⁰. In or out?","pause_after_s":2.5},{"id":"s8l1","style":"curious","visual":"PART 8/8 · te.definition-applied · objective: Decide whether coinage metals and zinc are transition elements. [CORE] Segment card in s7l12's pause ('PART 8 OF 8', 'Are coinage metals and zinc transition elements?' + objective); chip kept to the micro-recap. Line: split-screen (first-mentioned Cu left): Cu | Zn, both with full 3d boxes; '?' on cue 'transition'. RE-HOOK (cold open's Zn mystery).","tts_text":"الاتنين three d عشرة في الـ atom… بس واحد بس transition. مين؟","screen_text":"Both 3d¹⁰ in the atom. Only one is transition. Which?"},{"id":"s8l2","visual":"[CORE] TP. NEW TERM 'coinage metals' (book Exercise 1, p.10) on its cue; three coin glyphs labelled 'Cu', 'Ag', 'Au' on cues 'copper', 'silver', 'gold'. (Coins are the book's own name for the group, not decoration.)","tts_text":"طب الـ coinage metals: الـ copper والـ silver والـ gold… transition ولا لأ؟","screen_text":"Coinage metals: Cu, Ag, Au. Transition elements?"},{"id":"s8l3","visual":"[CORE] FB gate diagram (Part 7 model): Cu atom boxes 3d¹⁰ at gate 1, gate stays shut (coral) on cue 'complete'. Book Exercise 1.","tts_text":"أول اختبار: الـ copper atom فيه three d عشرة، complete خالص.","screen_text":"Test 1 · Cu atom: 3d¹⁰, complete ✕"},{"id":"s8l4","visual":"[CORE] FB: Cu²⁺ token: 4s ↑ and one 3d ↓ leave; boxes show 3d⁹ (one single) on cue 'تسعة'; gate 2 opens green.","tts_text":"تاني اختبار: الـ copper two، الـ three d فيها تسعة.","screen_text":"Test 2 · Cu²⁺: 3d⁹ ✓"},{"id":"s8l5","visual":"[CORE] FB: Cu passes gate 2, stamp 'transition element ✓' on cue 'transition'. Refutes misconception #1 (Cu not transition because atom is d¹⁰).","tts_text":"تسعة يعني ناقص، فالـ copper عنصر transition فعلاً.","screen_text":"Cu is a transition element ✓"},{"id":"s8l6","visual":"[CORE] TP. Rows (YK.formula 52, book p.10) 'Ag: 5s¹ 4d¹⁰ → Ag²⁺: 4d⁹' on cue 'silver', 'Au: 6s¹ 5d¹⁰ → Au³⁺: 5d⁸' on cue 'gold'; both stamped ✓ on cue 'ions' (this tts has no 'ناقص').","tts_text":"والـ silver والـ gold نفس الكلام في الـ ions بتاعتهم.","screen_text":"Ag, Au: +2 or +3 → d⁹ or d⁸ ✓"},{"id":"s8l7","visual":"[CORE] FB gate diagram: Zn atom boxes on cues 'four', 'three'; gate 1 shut. Book Exercise 2, p.11.","tts_text":"والـ zinc؟ الـ atom فيه four s اتنين، و three d عشرة.","screen_text":"₃₀Zn atom: 4s² 3d¹⁰"},{"id":"s8l8","visual":"[CORE] FB: Zn²⁺: 4s ↑↓ leave on cue 'four'; 3d stays full, label 'Zn²⁺: 3d¹⁰'; gate 2 shut (coral) on cue 'عشرة'.","tts_text":"الـ zinc two بيخسر الـ four s بس، فالـ three d تفضل عشرة.","screen_text":"Zn²⁺: 3d¹⁰"},{"id":"s8l9","visual":"[CORE] FB: Zn token stamped 'not a transition element' (coral) on cue 'transition'. Book: 'completely filled in both atomic state and oxidation state (+2)'.","tts_text":"في الـ atom وفي الـ ion، complete… فالـ zinc مش transition element خالص.","screen_text":"Complete in both → Zn is not a transition element"},{"id":"s8l10","visual":"[CORE] TP. [TTS FIX PENDING] New case from the book's Exercise 2 (p.11): 'Cd' tile slides in under the Zn tile (same group) on cue 'cadmium'; row '₄₈Cd atom: 5s² 4d¹⁰' (book order) with '4d¹⁰' gold on cue 'four'; stage: 5s + 4d boxes (YK.electronBoxes, labels '5s', '4d') full.","tts_text":"تحت الـ zinc فيه الـ cadmium: الـ atom فيه four d عشرة.","screen_text":"₄₈Cd atom: 5s² 4d¹⁰"},{"id":"s8l11","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: cadmium, book Exercise 2; not used earlier in this video). [TTS FIX PENDING] FB gate diagram (Part 7 model): Cd token before gate 1, its ion row 'Cd²⁺: 4d¹⁰' on cue 'two'; YK.checkPause question; think ring through the 3 s pause.","tts_text":"والـ cadmium two برضه four d عشرة. transition element ولا لأ؟ وقّفوا وفكّروا. <long pause>","screen_text":"Cd²⁺: 4d¹⁰. Is cadmium a transition element?","pause_after_s":3},{"id":"s8l12","visual":"[CORE] FB gate diagram: Cd bounces off gate 1 on cue 'atom' and gate 2 on cue 'ion' (both coral, shut); stamp 'not a transition element'; 'Zn', 'Hg' tiles join Cd in one column on cues 'zinc', 'mercury' with tag 'd¹⁰ in atom and +2 ion' + YK.rightMark. Book p.11 Exercise 2.","tts_text":"لأ: complete في الـ atom وفي الـ ion، زي الـ zinc والـ mercury بالظبط.","screen_text":"No: d¹⁰ in atom and ion, like Zn and Hg ✓"},{"id":"s8l13","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title:'Are coinage metals and zinc transition elements?', line:'Cu, Ag, Au: transition · Zn, Cd, Hg: not', formula:'d¹⁰ in atom and ion → not transition', pulse:[{word:'Cu', at:cue('s8l13','copper')}, {word:'Zn', at:cue('s8l13','zinc')}]}).","tts_text":"الخلاصة: الـ copper والـ silver والـ gold transition، والـ zinc لأ.","screen_text":"Cu, Ag, Au: transition · Zn, Cd, Hg: not"},{"id":"s8l14","visual":"[CORE] SO-WHAT into the closing · FB. The cold-open tag 'Same row. Why so different?' flies back to centre (match cut). Chip out.","tts_text":"كده نقدر نجاوب السؤال الكبير.","screen_text":"Now: the big question"},{"id":"z1","visual":"[CORE] CLOSING SUMMARY · FB. YK.flow({rtl:false, layout:'row', area:{x:96,y:340,w:1728,h:360}, node:{size:36}}) 5 nodes built left → right (the whole unit chain); node 1 '3d: singly, then pairing' with sub 'except Cr, Cu: half-filled / filled' (unvoiced sub covers Part 2) on cue 'singly'.","tts_text":"نلم الحلقة: الـ three d بتتملي singly، والـ pairing بعدين.","screen_text":"3d: singly, then pairing"},{"id":"z2","visual":"[CORE] FB flow: arrow + node 2 'Ions: 4s first' on cue 'four', arrow + node 3 'Fe²⁺ → Fe³⁺: half-filled' on cue 'iron'.","tts_text":"الـ ions بتخسر الـ four s الأول، والـ iron two بيتأكسد للـ half-filled بسهولة.","screen_text":"Ions: 4s first · Fe²⁺ → Fe³⁺: half-filled"},{"id":"z3","visual":"[CORE] FB flow: arrow + node 4 'Several oxidation states, up to +7' on cue 'oxidation'.","tts_text":"والـ four s والـ three d قريبين، فيه oxidation states كتير، لحد سبعة.","screen_text":"Several oxidation states, up to +7"},{"id":"z4","visual":"[CORE] FB flow: arrow + node 5 'Incomplete d orbitals: atom or ion' (gold) with sub 'Cu: yes · Zn: no' (covers Part 8) on cue 'orbitals'; the chain glows once.","tts_text":"والتعريف: الـ d orbitals ناقصة، في الـ atom أو في الـ ions بتاعته.","screen_text":"Incomplete d orbitals: atom or ion"},{"id":"z5","visual":"[CORE] BIG QUESTION ANSWERED (1/2) · split-screen (Mn left, Zn right, the cold-open pair): the gold tag 'Same row. Why so different?' top-centre. Mn boxes empty one by one 1…7 on cue 'كلهم', badge '+7' on cue 'سبعة'.","tts_text":"الـ manganese بيخسر الـ four s والـ three d كلهم، فيوصل لسبعة.","screen_text":"Mn: all of 4s + 3d lost → +7"},{"id":"z6","visual":"[CORE] Split right: Zn 4s ↑↓ leave on cue 'four', 3d¹⁰ stays; badge '+2' on cue 'اتنين'.","tts_text":"والـ zinc يخسر الـ four s بس، ويقف عند اتنين.","screen_text":"Zn: loses 4s only → +2"},{"id":"z7","visual":"[CORE] BIG QUESTION ANSWERED (2/2): Zn tile slides out of the d-block bracket for good, stamp 'not a transition element' on cue 'transition'; the gold big-question tag gets ✓.","tts_text":"والـ three d عشرة في الـ atom والـ ion، فمش transition element خالص.","screen_text":"Zn: 3d¹⁰ in atom and ion → not a transition element"},{"id":"z8","visual":"[CORE] RECALL 1/3 (Parts 1-2, book 'give reasons' form, Q7.1 p.27) · TP. YK.checkPause question; stage: empty Cu 4s + 3d boxes; think ring through the 3 s pause.","tts_text":"أول سؤال: اكتبوا الـ electronic configuration بتاع الـ copper، وليه؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"Write the electronic configuration of ₂₉Cu, and give the reason.","pause_after_s":3},{"id":"z9","visual":"[CORE] TP. Answer builds on cues 'argon', 'four', 'three'; 'filled' gold on its cue + YK.rightMark.","tts_text":"الإجابة: argon، والـ four s واحد، والـ three d عشرة… filled وأثبت.","screen_text":"₂₉Cu: [Ar] 4s¹ 3d¹⁰ (3d filled, more stable) ✓"},{"id":"z10","visual":"[CORE] RECALL 2/3 (Part 3, NEW case: Ni³⁺ from the book table, Ni₂O₃; not used in the shorts or lessons) · FB: Ni tile + empty boxes; YK.checkPause; think ring through the 3 s pause.","tts_text":"تاني سؤال: الـ nickel three، الـ three d فيها كام؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"₂₈Ni³⁺: how many 3d electrons?","pause_after_s":3},{"id":"z11","visual":"[CORE] FB. Ni boxes (4s² 3d⁸) lose 4s ↑↓ on cue 'four', then one 3d ↓ on cue 'three' → 3d⁷; answer 'Ni³⁺: [Ar] 3d⁷' + YK.rightMark.","tts_text":"سبعة: اتنين من الـ four s، وواحد من الـ three d بعدهم.","screen_text":"Ni³⁺: 3d⁷ ✓ (4s first, then one 3d)"},{"id":"z12","visual":"[CORE] RECALL 3/3 (Part 4, self-explanation in the book's 'give reasons' form) · TP. YK.checkPause; stage: Fe²⁺ boxes; think ring through the 3 s pause.","tts_text":"آخر سؤال، قولوها في جملة: ليه الـ iron two بيعمل oxidation بسهولة؟ <long pause>","screen_text":"Give reasons: easy oxidation of Fe²⁺ to Fe³⁺.","pause_after_s":3},{"id":"z13","visual":"[CORE] TP. Answer row 'Fe³⁺: [Ar] 3d⁵ half-filled → more stable' builds on cues 'iron', 'three', 'half-filled' + YK.rightMark.","tts_text":"عشان الـ iron three، الـ three d فيها خمسة: half-filled، أثبت.","screen_text":"Fe³⁺: 3d⁵ half-filled → more stable ✓"},{"id":"z14","visual":"[TRIM-IF-OVER 15:00 after narration; 2nd to cut] TEASER (labelled last line only) · FB strip of 10 tiles; label 'Next episode:' (Cairo 800 40, textDim) + 'General properties' (Cairo 1000 64). No subscribe. 0.8 s tail.","tts_text":"الحلقة الجاية: الـ general properties بتاعة العناصر دي.","screen_text":"Next episode: General properties"}],"logline":"Ten neighbours in one row, yet manganese reaches +7 while zinc stops at +2 and is not even a transition element. 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جيران في صف واحد من الـ scandium لحد\nالـ zinc في الآخر\nالـ manganese في النص بيوصل لسبعة موجب\nوالـ zinc اتنين بس\nوأغرب من كده الـ zinc قاعد في الـ d-block\nومش transition element أصلا\nإزاي جيران في نفس الصف يختلفوا كده\nالحلقة دي عن الـ electronic configuration\nوالـ oxidation states بتاعتهم\nبعد الـ calcium كل عنصر بيزوّد electron\nبيروح فين بالظبط\nالـ calcium بعد الـ argon قافل الـ four s\nباتنين\nفي الـ scandium الـ electron الجديد بيدخل\nالـ three d على طول\nفاكرين Hund's rule الـ electrons بتدخل\nsingly الأول والـ pairing بعدين\nومن الـ titanium لحد الـ manganese كل\norbital ياخد واحد لحد خمسة\nبعد الـ manganese يبدأ الـ pairing لحد الـ\nzinc بعشرة كاملين\nيلا نكتب الـ iron ستة وعشرين أول تمنتاشر\nنفس الـ argon بالظبط\nوبعدين الـ four s اتنين والـ three d الستة\nالباقيين\nناس كتير بتنسى الـ four s وتكتب الـ three\nd بس غلط\nطب الـ titanium اتنين وعشرين اكتبوا الـ\nelectronic configuration بتاعه وقّفوا\nثانية وفكّروا\nالإجابة argon والـ four s فيها اتنين والـ\nthree d اتنين\nالخلاصة three d بتتملي singly لحد الـ\nmanganese والـ pairing بعده\nبس فيه اتنين في الصف ده مش ماشيين على\nالقاعدة مين\nالمفروض الـ chromium يبقى four s اتنين و\nthree d أربعة بس لأ\nالكتاب بيكتبه argon والـ four s واحد والـ\nthree d خمسة\nالكتاب بيسميه anomalous يعني شاذ عن\nالمتوقع\nليه الـ four s بقت half-filled فيها\nelectron واحد\nوالـ three d فيها خمسة كل orbital فيه واحد\nhalf-filled برضه\nوالـ atom كده طاقته أقل وأثبت وده اسمه\nextra stability في الكتاب\nالـ copper نفس الحكاية المفروض four s\nاتنين و three d تسعة\nبس الحقيقة argon والـ four s واحد والـ\nthree d عشرة\nكده الـ four s تبقى half-filled والـ three\nd تبقى filled خالص\nبس الكتاب بينبّه ده مش العامل الوحيد\nللثبات\nطب الـ iron هينقل electron للـ three d زي\nالـ chromium وقّفوا وفكّروا\nلأ كده three d سبعة لا half-filled ولا\nfilled فمفيش extra stability هنا\nالخلاصة half-filled أو filled ده extra\nstability للـ atom كله\nطب لما الـ atom يخسر electrons ويبقى ion\nمين يمشي الأول\nالـ iron هيخسر اتنين electrons من أنهي\nsublevel بالظبط\nفاكرين الـ atom لما يخسر electrons بيبقى\nion موجب\nناس كتير فاكرة إن آخر electron دخل هو أول\nواحد يطلع\nغلط الـ four s هي الـ outer level\nفإلكتروناتها بتطلع الأول\nيخسر الاتنين بتوع الـ four s والـ three d\nتفضل زي ما هي\nيبقى الـ iron two فيه argon والـ three d\nستة\nولو خسر واحد كمان من الـ three d يبقى الـ\niron three بخمسة\nوكل عناصر الصف بتعمل ion اتنين موجب كده\nإلا الـ scandium لوحده\nالـ chromium فاكرينه four s واحد و three d\nخمسة\nطب الـ chromium three الـ three d فيها كام\nوقّفوا ثانية وفكّروا\nتلاتة الـ four s الأول وبعدها اتنين من الـ\nthree d كمان\nالخلاصة في الـ ions الـ four s بتطلع الأول\nوبعدين الـ three d بالترتيب\nخلّينا نلم اللي فات قبل ما نكمّل\nالـ three d بتتملي singly لحد الـ\nmanganese والـ pairing بعده\nالـ chromium والـ copper شذّوا عشان الـ\nhalf-filled والـ filled أثبت\nوفي الـ ions الـ four s بتطلع الأول\nالـ iron two بيخسر electron كمان بسهولة\nويبقى iron three ليه\nفاكرين الـ oxidation يعني الـ ion يخسر\nelectrons كمان\nالـ iron two زي ما شفنا three d فيها ستة\nلو خسر الـ electron ده يبقى الـ iron three\nوالـ three d خمسة\nوالـ three d خمسة يعني half-filled أثبت\nفالتفاعل بيروح ناحيته بسهولة\nمش عشان شحنة الـ iron three أكبر السبب الـ\nhalf-filled نفسه\nوالـ manganese الـ four s اتنين والـ three\nd خمسة\nطب الـ manganese two هيتأكسد بسهولة لـ\nmanganese three وقّفوا ثانية وفكّروا\nلأ الـ manganese two بيخسر الـ four s بس\nفالـ three d خمسة\nالخلاصة الـ iron two بيجري على الـ\nhalf-filled والـ manganese two قاعد فيه\nأصلا\nطب من الـ scandium للـ zinc كل واحد يوصل\nلكام\nالـ manganese بيوصل لسبعة والـ zinc جنبه\nبيقف عند اتنين إزاي\nفاكرين الـ oxidation state الشحنة اللي\nالعنصر بياخدها جوه المركّب\nفي الـ potassium permanganate الـ\npotassium واحد والـ oxygen سالب تمانية\nفالـ manganese سبعة\nمن الـ scandium للـ manganese أعلى\noxidation state بيزيد لحد سبعة\nبعد الـ manganese الأعلى بيقل تدريجيا لحد\nالـ zinc اتنين بس\nوالـ iron مبيوصلش لتمانية أعلاه ستة\nوالمهمين اتنين وتلاتة بس\nوالقاعدة أعلى oxidation state مبيعديش رقم\nالـ group بتاعته\nإلا group الـ copper والـ silver والـ gold\nبيعدّوا الرقم ده\nالـ rhenium في group سبعة زي الـ manganese\nأعلى oxidation state كام وقّفوا وفكّروا\nسبعة ومبيعديهاش عشان رقم الـ group بتاعه\nسبعة\nالخلاصة بيطلع لحد سبعة في الـ manganese\nوينزل لحد الـ zinc عند اتنين\nطب ليه عندهم oxidation states كتير أصلا مش\nواحدة بس\nالـ sodium بيقف عند electron واحد والـ\nvanadium يوصل لخمسة ليه\nفاكرين الـ ionization energy طاقة شيل\nelectron وكل واحد بعده أغلى\nهنا الـ four s والـ three d قريبين في\nالطاقة\nخلّينا نشوف الـ vanadium فيه four s اتنين\nو three d تلاتة\nأول electron من الـ four s ستمية تمانية\nوأربعين\nوالتاني من الـ four s كمان ألف تلتمية ستة\nوأربعين\nوالتالت من الـ three d ألفين تمنمية تمانية\nوخمسين\nوبعدها أربعة آلاف ستمية تلاتة وأربعين وستة\nآلاف خمسمية تلاتة وعشرين\nيعني مفيش قفزة ضخمة بعد الـ four s الزيادة\nتدريجية\nوالـ titanium ليه oxidation state واحدة\nولا كذا واحدة وقّفوا ثانية وفكّروا\nكذا حالة اتنين وتلاتة وأربعة عشان الـ four\ns والـ three d قريبين\nالخلاصة الـ four s والـ three d قريبين\nفيبقى فيه oxidation states كتير\nطب مين بالظبط اللي يستاهل اسم transition\nelement أصلا\nنلم تاني الـ iron two بيتأكسد بسهولة عشان\nالـ half-filled أثبت\nوالـ oxidation states بتطلع لحد سبعة في\nالـ manganese وبتنزل بعده\nوهي كتير عشان الـ four s والـ three d\nقريبين في الطاقة\nالـ scandium three الـ three d فاضية خالص\nيفضل transition element ولا لأ\nالـ transition element الـ d orbitals أو\nالـ f orbitals فيها electrons بس\nمش complete في الـ atomic state أو في\nواحدة من الـ oxidation states بتاعته\nيعني اختبارين الـ atom الأول وبعدين الـ\nions بتوعه\nنطبّق على الـ scandium الـ atom فيه three\nd واحد\nفيه electrons ومش complete يبقى transition\nelement من أول اختبار\nومش مهم إن الـ scandium three فاضي اختبار\nواحد كفاية\nفي الـ vanadium pentoxide الـ vanadium\nبيبقى three d صفر\nالـ vanadium يفضل transition element ولا\nلأ وقّفوا ثانية وفكّروا\nأيوه الـ atom نفسه three d تلاتة واختبار\nواحد كفاية\nالخلاصة الـ d orbitals ناقصة في الـ atom\nأو في oxidation state واحدة\nطب والـ copper والـ zinc اللي الـ atom\nبتاعهم three d عشرة\nالاتنين three d عشرة في الـ atom بس واحد\nبس transition مين\nطب الـ coinage metals الـ copper والـ\nsilver والـ gold transition ولا لأ\nأول اختبار الـ copper atom فيه three d\nعشرة complete خالص\nتاني اختبار الـ copper two الـ three d\nفيها تسعة\nتسعة يعني ناقص فالـ copper عنصر transition\nفعلا\nوالـ silver والـ gold نفس الكلام في الـ\nions بتاعتهم\nوالـ zinc الـ atom فيه four s اتنين و\nthree d عشرة\nالـ zinc two بيخسر الـ four s بس فالـ\nthree d تفضل عشرة\nفي الـ atom وفي الـ ion complete فالـ zinc\nمش transition element خالص\nتحت الـ zinc فيه الـ cadmium الـ atom فيه\nfour d عشرة\nوالـ cadmium two برضه four d عشرة\ntransition element ولا لأ وقّفوا وفكّروا\nلأ complete في الـ atom وفي الـ ion زي الـ\nzinc والـ mercury بالظبط\nالخلاصة الـ copper والـ silver والـ gold\ntransition والـ zinc لأ\nكده نقدر نجاوب السؤال الكبير\nنلم الحلقة الـ three d بتتملي singly والـ\npairing بعدين\nالـ ions بتخسر الـ four s الأول والـ iron\ntwo بيتأكسد للـ half-filled بسهولة\nوالـ four s والـ three d قريبين فيه\noxidation states كتير لحد سبعة\nوالتعريف الـ d orbitals ناقصة في الـ atom\nأو في الـ ions بتاعته\nالـ manganese بيخسر الـ four s والـ three\nd كلهم فيوصل لسبعة\nوالـ zinc يخسر الـ four s بس ويقف عند\nاتنين\nوالـ three d عشرة في الـ atom والـ ion فمش\ntransition element خالص\nأول سؤال اكتبوا الـ electronic\nconfiguration بتاع الـ copper وليه وقّفوا\nثانية وفكّروا\nالإجابة argon والـ four s واحد والـ three\nd عشرة filled وأثبت\nتاني سؤال الـ nickel three الـ three d\nفيها كام وقّفوا ثانية وفكّروا\nسبعة اتنين من الـ four s وواحد من الـ\nthree d بعدهم\nآخر سؤال قولوها في جملة ليه الـ iron two\nبيعمل oxidation بسهولة\nعشان الـ iron three الـ three d فيها خمسة\nhalf-filled أثبت\nالحلقة الجاية الـ general properties بتاعة\nالعناصر دي","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"series_id":"chem-s3-en.ch1#sessions","episode_no":3,"episode_count":9,"lessons":["chem-s3-en.lesson-atom.electron-configuration-writing","chem-s3-en.lesson-atom.hund-rule","chem-s3-en.lesson-pt.ionization-energy","chem-s3-en.lesson-te.cr-cu-anomaly","chem-s3-en.lesson-te.definition","chem-s3-en.lesson-te.definition-applied","chem-s3-en.lesson-te.electron-configuration","chem-s3-en.lesson-te.fe2-fe3-mn2-stability","chem-s3-en.lesson-te.ion-configuration","chem-s3-en.lesson-te.multiple-oxidation-states","chem-s3-en.lesson-te.oxidation-states-trend"]},{"id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","version":1,"ord":262,"content_lang":"ar-EG","primary_concept_id":"te.atomic-mass-trend","concepts":[{"concept_id":"te.atomic-mass-trend","role":"primary"},{"concept_id":"te.atomic-radius","role":"secondary"},{"concept_id":"te.density-trend","role":"secondary"},{"concept_id":"te.high-melting-points","role":"secondary"},{"concept_id":"te.metallic-properties","role":"secondary"}],"title":"General properties: mass, radius and metallic property","payload":{"title":"General properties: mass, radius and metallic property","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"16:9","format":"episode","script":[{"id":"c1","visual":"[CORE] COLD OPEN · FB. EPISODE MODELS (director pass; reuse in every part, one model + colour per thing, E11): (a) DATA TABLE = the book's table p.12, ALWAYS full-bleed (x 96–1824, y 150–1000; no text panel beside it): header row + 9 rows Sc → Cu, columns 'Element' · 'Atomic mass' · 'Atomic radius' · 'Density g/cm^3' · 'Melting point °C' · 'Boiling point °C', book values only, all numbers YK.label mono 40; tag 'Book table (for illustration only)' Cairo 600 32 textDim under it; one column lit per part (gold header), others at 25%. (b) STRIP = 9 custom tiles Sc → Cu (YK.roundRect 168×168, gap 26, x 96–1824, violet 25% fill), symbol YK.label 72, Z as a small mono 32 number top-left of the tile (no Unicode pre-subscripts, no dBlockZoom: it always draws Zn; the book table stops at Cu). (c) ATOM = dashed circle at the book radius + gold nucleus dot, r_px = k × radius with ONE k per shot: k = 200 single/pair shots, k = 62 the nine-in-a-row (Sc 89 px … Cu 73 px, slot 192 px), k = 45 mini rows. (d) ELECTRON SEA = YK.lattice({rows:4, cols:6, charge:'+', sea:{count, t, color:C.cyan, seed:7}}): steel ion discs with '+', cyan free electrons (count rises = more electrons, same seed so old dots stay). (e) CUBE = custom 1 cm^3 box (front square + top parallelogram) packed with small YK.atomDisc + mono mass readout. (f) THERMOMETER = custom tube + bulb, ONE scale 0–2000 °C for the whole episode, value YK.label mono 64. (g) TUG = YK.tug (kit colours: inward violet = nucleus pull, outward cyan = 3d repulsion; labels empty until the term is spoken, then 'effective nuclear charge' / '3d repulsion'). Shot: STRIP across the frame (y ≈ 520) on screen from frame 0 at 40%, tiles land left → right (YK.stagger 0.08/0.4 s); Sc glows on cue 'scandium', Cu on cue 'copper'. Drift ≤ 2%. Book table p.12.","tts_text":"تسع معادن في صف واحد: من الـ scandium لحد الـ copper في الآخر.","screen_text":"Sc (21) → Cu (29)"},{"id":"c2","visual":"[CORE] FB split (first-mentioned left): left a CUBE of Cu, right a CUBE of Sc, same size; mass readouts '8.92 g' on cue 'copper' and '3.10 g' on cue 'scandium' (YK.label 72 mono); YK.balance under them (left 'Cu', right 'Sc') tips left-down (value −0.6) on cue 'تلات'. Book table p.12 density column (8.92 / 3.10 ≈ 2.9).","tts_text":"حتة copper، أتقل حوالي تلات مرات من حتة scandium بنفس الحجم.","screen_text":"1 cm³ each: Cu 8.92 g · Sc 3.10 g"},{"id":"c3","visual":"[CORE] FB. Fe tile from the STRIP grows to centre; a THERMOMETER (episode scale) fills from 0 to '1538 °C' (YK.label 72 mono) between cues 'يسيح' and 'درجة'; tile edge glows orange. Book table p.12.","tts_text":"والـ iron؟ عشان يسيح، محتاج أكتر من ألف وخمسمية درجة.","screen_text":"Fe melts at 1538 °C"},{"id":"c4","style":"curious","visual":"[CORE] BIG QUESTION · FB. Cube + thermometer dim to 30%; card centred (Cairo 1000 88, 6 words) on line start, held through the pause, then shrinks to a gold tag top-right (returns in z6).","tts_text":"ليه الـ density عالية كده… والـ melting point عالي كده؟","screen_text":"Why such high density and melting points?","pause_after_s":1},{"id":"t1","visual":"[CORE] TITLE CARD 0–4 s from line start: YK.titleCard({title:'General properties: mass, radius and metallic property', chip:'Unit 4', subtitle:'Chapter 1: Transition Elements'}) Cairo 1000 110, 2 lines. Parts row is CUSTOM (titleCard has none): 2 columns × 3 rows under the title, YK.para Cairo 800 32 textDim, maxWidth 800: '1 Atomic mass: why nickel is abnormal' · '2 Atomic radius: nearly constant' · '3 The metallic property' · '4 High melting and boiling points (the data)' · '5 High melting and boiling points (the reason)' · '6 Density increases with atomic number'. At 4.0 s camera move (1.2 s, no fade) onto the parts row; items 1, 2, 3 turn white on cues 'mass', 'radius', 'metallic'. In the 2.5 s pause item 1 grows into the PART 1 card.","tts_text":"الحلقة دي عن الـ general properties: الـ mass، والـ radius، والـ metallic property بتاعتهم.","screen_text":"General properties: mass, radius and metallic property","pause_after_s":2.5},{"id":"s1l1","style":"curious","visual":"PART 1/6 · te.atomic-mass-trend · objective: Describe the atomic mass trend and explain why nickel is abnormal. · [CORE] Segment card in t1's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 1 OF 6', title:'Atomic mass: why nickel is abnormal', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Atomic mass: why nickel is abnormal', never cut) on line start, chip kept to the micro-recap. Line: FB STRIP; Ni tile lifts on cue 'nickel', Co tile on cue 'cobalt' (strip order stays Co left of Ni); a YK.balance (left 'Co', right 'Ni', value 0) with a gold '?' between them on cue 'أتقل'. RE-HOOK.","tts_text":"الـ nickel بعد الـ cobalt في الجدول… يبقى أتقل منه، صح؟","screen_text":"Ni (Z = 28) comes after Co (Z = 27). Heavier?"},{"id":"s1l2","visual":"[CORE] FB DATA TABLE (shot change): 'Atomic mass' column lit; a gold arrow runs down the column on cue 'بالتدريج'; gold tag 'increases gradually' (Cairo 800 44) beside the lit column on cue 'mass' (table is full-bleed, no text panel). Book p.12 point 1.","tts_text":"الكتاب بيقول: الـ atomic mass بتزيد بالتدريج، كل ما الـ atomic number يزيد.","screen_text":"Atomic mass increases gradually with atomic number"},{"id":"s1l3","visual":"[CORE] TP. Stage: YK.chart({type:'bar', data: the 9 book masses Sc 45 … Cu 63.5, yRange:[40,65], yLabel:'Atomic mass', highlight:['Co','Ni'], hp: on cue 'cobalt'}); values '58.9' / '58.7' (YK.label 56 mono at chart.px/py) pop above Co on cue 'cobalt' and Ni on cue 'nickel'. Text panel: 'Co 58.9 · Ni 58.7' builds on the same cues.","tts_text":"بس بصّوا هنا: الـ cobalt والـ nickel، الاتنين حوالي تسعة وخمسين.","screen_text":"Co 58.9 · Ni 58.7"},{"id":"s1l4","visual":"[CORE] TP. NEW TERM 1 'abnormal'. On the full chart the 0.2 u gap is only ~5 px, so a zoom lens (circle 300 px, YK.scaleBadge) opens over the Co/Ni bar tops with its own labelled axis 58.5–59.0: Ni's top clearly below Co's, coral bracket. Text panel: 'Nickel is abnormal' (Cairo 1000 64, gold) on cue 'abnormal'. Book p.12 point 1.","tts_text":"والـ nickel مع إنه بعده، أخف شوية… فالكتاب بيقول إنه abnormal هنا.","screen_text":"Nickel is abnormal"},{"id":"s1l5","visual":"[CORE] TP. MISCONCEPTION (te.atomic-mass-trend #1). Small coral tag 'A misprint?' on the Ni value, YK.wrongMark on cue 'لأ' (< 2 s, smaller than the gold label).","tts_text":"ناس كتير بتقول: أكيد غلطة مطبعية في الجدول. لأ، مش غلطة.","screen_text":"A misprint? ✕"},{"id":"s1l6","visual":"PREREQ atom.isotopes [RECAP-PREREQ] (s1l6 + s1l7 ≤ 20 s, reference only) · FB (shot change). Prereq YK.chip (link icon) 'Isotopes and average atomic mass' under the segment chip. SAME MODEL as video-short-atom.isotopes: two packed nuclei (proton discs + grey neutron discs) 'chlorine-35' (left) and 'chlorine-37' (right); label 'isotopes' on cue 'isotopes'; the two extra neutrons of chlorine-37 pulse + label 'neutrons' on cue 'neutrons'.","tts_text":"فاكرين الـ isotopes؟ نفس الـ element، بس عدد الـ neutrons مختلف.","screen_text":"Isotopes: same element, different numbers of neutrons"},{"id":"s1l7","visual":"PREREQ atom.isotopes [RECAP-PREREQ] FB. The short's number line 35 — 37 slides in under the nuclei: gold pointer settles at 35.5 + label 'average' (YK.label 56) on cue 'متوسط'; '35.5' tagged 'atomic mass' on cue 'atomic'. Prereq chip out at line end.","tts_text":"والـ atomic mass اللي في الجدول، متوسط الـ isotopes دي كلها.","screen_text":"Atomic mass = average of the isotopes"},{"id":"s1l8","visual":"[CORE] FB (shot change). Five Ni nuclei (Ni-58, 60, 61, 62, 64 as small tags) pop in a row on cue 'stable' (stagger 0.12 s); label 'five stable isotopes' (Cairo 800 44) on cue 'isotopes'. Book p.12 point 1.","tts_text":"والـ nickel عنده خمس stable isotopes، وكتلته متوسط الخمسة دول.","screen_text":"Ni: five stable isotopes"},{"id":"s1l9","visual":"[CORE] FB. The five nuclei collapse into one share bar (x 200–1720), segment widths at the natural mix (Ni-58 ≈ 68%, Ni-60 ≈ 26%, Ni-61/62/64 thin slivers; no % printed): Ni-58 segment (mint) grows on cue 'الخفيف'; tag 'nickel-58' on cue 'تمانية'. Matches lesson-te.atomic-mass-trend ('Most nickel atoms are the light isotope nickel-58').","tts_text":"وأغلب الـ atoms بتاعة الـ nickel من النوع الخفيف، nickel تمانية وخمسين.","screen_text":"Most Ni atoms: light nickel-58"},{"id":"s1l10","visual":"[CORE] TP. Text panel: 'Ni average 58.7 u < Co 58.9 u' (YK.formula 56) on cue 'cobalt'; small tag 'more protons (28 vs 27)' on cue 'protons'. Stage: the s1l7 number-line model, now 58 — 60, with a Co mark at 58.9; the gold pointer settles at 58.7, just left of it, on cue 'بينزل'.","tts_text":"فالمتوسط بينزل تحت الـ cobalt، حتى لو الـ protons أكتر.","screen_text":"More protons, but average 58.7 u < Co 58.9 u"},{"id":"s1l11","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: a changed isotope mix). FB stage: the share bar with the Ni-60 segment ghost-swollen to ~70% (dashed) on cue 'ستين'; YK.checkPause question in the TEXT PANEL (16:9 has no top band); think ring from cueEnd through the 3 s pause.","tts_text":"لو أغلب الـ nickel كان nickel ستين، هيفضل أخف من الـ cobalt؟ وقّفوا وفكّروا. <long pause>","screen_text":"If most nickel were nickel-60, would Ni still be lighter than Co?","pause_after_s":3},{"id":"s1l12","visual":"[CORE] FB. The pointer slides past Co's 58.9 mark toward 60 on cue 'هيعدّي'; answer slot + YK.rightMark on cue 'الخليط'.","tts_text":"لأ: المتوسط كان هيعدّي الـ cobalt… يعني الخليط هو اللي بيفرق.","screen_text":"No: the average would rise above Co's 58.9 ✓"},{"id":"s1l13","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title:'Atomic mass: why nickel is abnormal', line:'Atomic mass increases gradually; Ni is abnormal (five stable isotopes)', formula:'Ni 58.7 u < Co 58.9 u', pulse:[{word:'gradually', at:cue(s1l13,'بالتدريج')}, {word:'isotopes', at:cue(s1l13,'isotopes')}]}). Stage: mass bars.","tts_text":"الخلاصة: الـ atomic mass بتزيد بالتدريج، والـ nickel abnormal عشان الـ stable isotopes بتاعته.","screen_text":"Atomic mass increases gradually; Ni is abnormal (five stable isotopes)"},{"id":"s1l14","visual":"[CORE] SO-WHAT · FB. Mini mass bars rise on cue 'الكتلة'; then ATOM (k = 200, Sc r 288 px) with a gold '?' on cue 'atom'. Segment chip out at line end; in the pause: camera push into the PART 2 card.","tts_text":"الكتلة بتزيد… طب حجم الـ atom بيزيد معاها؟","screen_text":"Mass goes up. Does the atom get bigger?","pause_after_s":2.5},{"id":"s2l1","style":"curious","visual":"PART 2/6 · te.atomic-radius · objective: Explain why the atomic radius is nearly constant from Cr to Cu. · [CORE] Segment card in s1l14's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 2 OF 6', title:'Atomic radius: nearly constant', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Atomic radius: nearly constant', never cut) on line start, chip kept to the micro-recap. Line: FB STRIP Cr → Cu lit; '+5 protons' (YK.label 56, mono digits) on cue 'protons'; a shrinking-arrow '?' over the Cu tile on cue 'يصغر'. RE-HOOK (misconception #1).","tts_text":"من الـ chromium للـ copper، زوّدنا خمس protons… المفروض الـ atom يصغر، صح؟","screen_text":"Cr → Cu: 5 more protons. Smaller atoms?"},{"id":"s2l2","visual":"PREREQ pt.atomic-radius-trend [RECAP-PREREQ] (s2l2 + s2l3 ≤ 20 s, reference only) · FB. Prereq YK.chip (link icon) 'Atomic radius trend'. SAME MODEL as video-short-pt.atomic-radius-trend: two Bohr atoms, YK.atom Na {shells:[2,8,1], size 230} LEFT on cue 'sodium', Cl {shells:[2,8,7], size 122} RIGHT on cue 'chlorine' (no Na → Cl row); gold arrow Na → Cl + label 'atomic radius decreases' on cue 'atomic'.","tts_text":"فاكرين الـ period التالت؟ من الـ sodium للـ chlorine، الـ atomic radius بيقل بوضوح.","screen_text":"Period 3, Na → Cl: atomic radius decreases"},{"id":"s2l3","visual":"PREREQ pt.atomic-radius-trend [RECAP-PREREQ] FB. Labels '11 p^+' / '17 p^+' under Na / Cl on cue 'protons'; four inward arrows on Cl's outer ring thicken + label 'stronger pull' on cue 'nucleus'. Prereq chip out at line end.","tts_text":"عشان الـ protons بتزيد، والشد ناحية الـ nucleus بيقوى.","screen_text":"More protons → stronger pull"},{"id":"s2l4","visual":"[CORE] FB (shot change): the 9 ATOM circles Sc → Cu at book radii in a row (k = 62, slot 192 px; Sc 1.44 … Cu 1.17), drawn left → right on cue 'atomic'; label 'little change' on cue 'شوية'; then circles Cr → Cu get a gold outline + radius values (1.17 · 1.17 · 1.16 · 1.16 · 1.15 · 1.17, YK.label 40) staggered 0.25 s from cue 'chromium' (Cu's lands by cue 'copper') and a flat dashed line along their tops + label 'nearly constant' on cue 'ثابت'. Book pp.12–13 point 2.","tts_text":"بس هنا؟ الـ atomic radius بيتغير شوية، ومن الـ chromium للـ copper تقريباً ثابت.","screen_text":"Little change in atomic radii · Cr → Cu: nearly constant"},{"id":"s2l5","visual":"[CORE] FB split (first-mentioned left): period-3 pair Na → Cl (steep, the s2l2 model) | Cr → Cu circles (flat, k = 45); coral ✕ on a small 'falls sharply?' tag on cue 'جامد' (< 2 s, smaller than the flat row). MISCONCEPTION te.atomic-radius #1. QUICK MID-SEGMENT CHECK (Part 2 can exceed 120 s at 1.75 w/s): 'Why doesn't it fall sharply?' (Cairo 800 44, text panel) on cue 'ليه' + YK.thinkRing through pause_after_s 1.5.","tts_text":"يعني مش بيقل جامد زي الـ period التالت. طب ليه؟","screen_text":"Falls sharply, as in period 3? ✕ · Why not?","pause_after_s":1.5},{"id":"s2l6","visual":"[CORE] TP. NEW TERM 'opposite factors' (Cairo 1000 64) on cue 'opposite'. Stage: TUG (YK.tug, el 'Fe', r 260, labels empty): inward violet arrows grow (pull 0 → 1) on cue 'بيصغّر', outward cyan arrows (push 0 → 1) on cue 'بيكبّره'. Book p.12 'two opposite factors'.","tts_text":"الكتاب بيسميهم opposite factors: واحد بيصغّر الـ atom، والتاني بيكبّره.","screen_text":"Two opposite factors"},{"id":"s2l7","visual":"[CORE] TP. NEW TERM 2 'effective nuclear charge' (≥ 1 s after term 1). The segment's one definition card YK.termCard({term:'Effective nuclear charge', def:'The pull of the nucleus that the outer electrons actually feel.', keys:['pull']}) on cue 'nuclear'. Stage: TUG, push faded to 0.3, pull label 'effective nuclear charge' appears on cue 'effective'.","tts_text":"أول factor: من الـ scandium للـ chromium، الـ effective nuclear charge بيزيد.","screen_text":"Factor 1 (Sc → Cr): effective nuclear charge ↑"},{"id":"s2l8","visual":"[CORE] FB (shot change). ATOM sequence Sc → Ti → V → Cr (k = 110, book radii 1.44 · 1.32 · 1.22 · 1.17, values YK.label 40) left → right on cue 'electrons'; violet inward arrows thicken left → right; '1.44 → 1.17' + label 'Factor 1: radius ↓' on cue 'atomic'. Book p.13.","tts_text":"ومع زيادة الـ electrons، شد الـ nucleus عليهم بيزيد، فالـ atomic radius بيقل.","screen_text":"More electrons, stronger pull → atomic radius ↓"},{"id":"s2l9","visual":"[CORE] FB. YK.configStrip (size 100, centred) stepping Z 21 → 29 one element per 0.45 s from cue 'three', book configs incl. Cr 4s^1 3d^5 and Cu 4s^1 3d^10 (do NOT fill the 3d boxes 1 → 10 continuously: that draws Cr as 3d^4); holds on Cu; on cue 'بتزق' the 3d electrons jitter apart with short cyan push arrows.","tts_text":"تاني factor: الـ three d بتتملي، والـ electrons اللي فيها بتزق بعض.","screen_text":"Factor 2: more 3d electrons"},{"id":"s2l10","visual":"[CORE] TP. NEW TERM 3 'repulsion' (Cairo 1000 64, cyan) on cue 'repulsion'. Stage: TUG, pull faded to 0.3, push 1: outward cyan arrows, ring grows (kit: r·(1 + 0.12·(push − pull))) on cue 'بيزيد'; push label '3d repulsion'; text 'Factor 2: radius ↑'. Book p.13 point b.","tts_text":"والـ repulsion بين الـ electrons دي بتوسّع الـ atom، فالـ atomic radius بيزيد.","screen_text":"Repulsion between 3d electrons → radius ↑"},{"id":"s2l11","visual":"[CORE] FB tug-of-war: TUG at (620, 560), r 230, pull = push = 1 on cue 'بيلغوا' (ring returns to its rest size), both labels on; right: mini Cr → Cu circle row (k = 45, x 1120–1800) with the flat dashed line returns on cue 'ثابت' + label 'relatively constant' (book wording).","tts_text":"الـ opposite factors بيلغوا بعض تقريباً، فالـ atomic radius بيفضل ثابت نسبياً.","screen_text":"Two opposite factors → atomic radius relatively constant"},{"id":"s2l12","visual":"[CORE] FB. YK.lattice 4×6 of Cr discs (YK.atomColor) with three Mn discs substituted on cue 'alloys' (both 1.17: same size, they fit) — NOT Fe/Ni (that is the s2l13 predict pair); label 'used in making alloys' (book p.13). No alloy-type names (Unit 7).","tts_text":"وعشان أحجامهم قريبة كده، بيستخدموهم في عمل الـ alloys مع بعض.","screen_text":"Similar sizes → used in making alloys"},{"id":"s2l13","visual":"[CORE] PAUSE-AND-PREDICT (NEW pair Fe/Ni, not drawn before). Stage: Fe and Ni ATOM circles (k = 200) side by side with radius tags '1.16' / '1.15' on cues 'iron', 'nickel'; YK.checkPause in the text panel; think ring through the 3 s pause.","tts_text":"الـ iron والـ nickel، ينفع يدخلوا مع بعض في alloy بسهولة؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"Fe (1.16) and Ni (1.15): can they mix easily in an alloy?","pause_after_s":3},{"id":"s2l14","visual":"[CORE] FB. The Fe and Ni circles slide to overlap (same size) on cue 'atomic'; then a YK.lattice of Fe discs with one Ni disc substituted on cue 'مكان'; answer slot + YK.rightMark.","tts_text":"أيوه: الـ atomic radius بتاعهم تقريباً واحد، فيدخلوا مكان بعض بسهولة.","screen_text":"Yes ✓ nearly the same atomic radius"},{"id":"s2l15","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title:'Atomic radius: nearly constant', line:'Nucleus pulls · 3d repulsion pushes → nearly constant', pulse:[{word:'pulls', at:cue(s2l15,'nucleus')}, {word:'repulsion', at:cue(s2l15,'repulsion')}]}). Stage: TUG, pull = push = 1.","tts_text":"الخلاصة: الـ nucleus بيشد، والـ repulsion بتزق… فالـ atomic radius تقريباً ثابت.","screen_text":"Nucleus pulls · 3d repulsion pushes → nearly constant"},{"id":"s2l16","visual":"[CORE] SO-WHAT · FB. Mass bars (Part 1) and flat circle row (Part 2) side by side, each pulses on its cue ('الكتلة', 'الحجم'); a small gold link icon between them (pays off in Part 6). Segment chip out.","tts_text":"يعني الكتلة بتزيد والحجم ثابت… خلّوا الاتنين دول في دماغكم.","screen_text":"Mass ↑, size nearly constant. Keep both in mind.","pause_after_s":1},{"id":"m1l1","visual":"[CORE] MID-EPISODE RECAP 1 (~4:30) · FB. YK.flow({rtl:false, layout:'row', area:{x:96,y:380,w:1728,h:320}, node:{size:40}}); header 'So far' (Cairo 800 40) top-left. Node 1 'Atomic mass ↑' (sub 'Ni abnormal') (mini bar glyph) on cue 'atomic'.","tts_text":"نلم اللي فات: الـ atomic mass بتزيد، بس الـ nickel abnormal فيها.","screen_text":"Atomic mass ↑ · Ni abnormal"},{"id":"m1l2","visual":"[CORE] FB flow: arrow + node 2 'Atomic radius nearly constant' (sub 'two opposite factors', flat-circles glyph) on cue 'atomic'; nodes 1-2 glow once. In the pause: camera move into the PART 3 card.","tts_text":"والـ atomic radius تقريباً ثابت، عشان الـ opposite factors دول.","screen_text":"Atomic radius nearly constant (two opposite factors)","pause_after_s":2.5},{"id":"s3l1","style":"curious","visual":"PART 3/6 · te.metallic-properties · objective: Describe the metallic property of the first transition series. · [CORE] Segment card in m1l2's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 3 OF 6', title:'The metallic property', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'The metallic property', never cut) on line start, chip kept to the micro-recap. Line: FB split: YK.beaker of water, metal piece, bubbles 0.9 on cue 'بعنف' (left) | YK.beaker, metal piece, bubbles 0.05 on cue 'بالعافية' (right); no metal names yet. RE-HOOK.","tts_text":"معادن من نفس الصف… بس واحد بيتفاعل مع المية بعنف، وواحد بالعافية.","screen_text":"Same row: one reacts strongly with water, one hardly reacts"},{"id":"s3l2","visual":"[CORE] FB STRIP (shot change): all 9 tiles become metal blocks (grey bevel) on cue 'solid'; label 'All of them are solid' (book p.13 point a).","tts_text":"نبدأ باللي بيجمعهم: كلهم solid في الظروف العادية.","screen_text":"All of them are solid"},{"id":"s3l3","visual":"[CORE] FB STRIP. NEW TERM 1 'metallic luster': a light sweep glints across the blocks on cue 'بيلمعوا'; label 'metallic luster' (Cairo 1000 64) on cue 'metallic'.","tts_text":"وكلهم بيلمعوا لمعة المعادن، دي اسمها metallic luster في الكتاب.","screen_text":"Metallic luster"},{"id":"s3l4","visual":"[CORE] TP. NEW TERM 2 'good conductivity'. Stage, first-mentioned left: a block with a heat wave crossing it on cue 'heat' | a block in a simple circuit (lines + YK.icon 'lamp' + glow) lights on cue 'electricity'. Text panel: 'good conductivity of heat and electricity' (book p.13).","tts_text":"وكلهم عندهم good conductivity للـ heat والـ electricity كمان.","screen_text":"Good conductivity of heat and electricity"},{"id":"s3l5","visual":"[CORE] TP. NEW TERM 3 'activity' (book 'variation in their activity'): headline 'Variation in their activity' (Cairo 1000 64) on cue 'activity'; the STRIP blocks lose their identical look (three get different tints) on cue 'بيختلفوا'.","tts_text":"بس الـ activity بتاعتهم؟ هنا بقى بيختلفوا جامد.","screen_text":"But: variation in their activity"},{"id":"s3l6","visual":"PREREQ chem.activity-series [RECAP-PREREQ] (≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Chemical activity series of metals'. Stage: SAME MODEL as video-short-chem.activity-series: the vertical ladder with the dashed 'hydrogen' line; top rung tagged 'very active'; a YK.beaker of water beside it gives H2 bubbles on cue 'hydrogen'.","tts_text":"فاكرين الـ activity series؟ المعدن النشيط أوي بيطرد الـ hydrogen من المية.","screen_text":"Activity series: very active metals replace the hydrogen of water"},{"id":"s3l7","visual":"[CORE] FB triptych (book order left → right: Cu | Fe | Sc, identical panels). Panel 1: Cu strip in water, nothing happens; label 'limited chemical activity' on cue 'limited'. Book p.13 point d.","tts_text":"والـ copper، الـ chemical activity بتاعته limited، مش بيتفاعل بسهولة.","screen_text":"Copper: limited chemical activity"},{"id":"s3l8","visual":"[CORE] FB triptych panel 2: Fe nail in air (book: 'goes rusty if it exposed to air'), rust spots spread on cue 'بيصدّي'; label 'moderate (goes rusty in air)' on cue 'moderate'.","tts_text":"والـ iron في النص، moderate: بيصدّي لو اتساب في الهوا.","screen_text":"Iron: moderate, goes rusty in air"},{"id":"s3l9","visual":"[CORE] FB triptych panel 3: Sc in water, strong bubbles (H₂ tag) on cue 'hydrogen'; label 'highly active' on cue 'highly'. Panels now read limited → moderate → highly active.","tts_text":"وآخرهم الـ scandium، ده highly active: بيطرد الـ hydrogen من المية بقوة.","screen_text":"Scandium: highly active, replaces the hydrogen of water strongly"},{"id":"s3l10","visual":"[CORE] FB triptych. MISCONCEPTIONS te.metallic-properties #1 and #2: small coral tags 'All unreactive like Cu?' over the Cu panel and 'All react strongly with water?' over the Sc panel, each YK.wrongMark on cues 'copper' and 'scandium' (< 2 s); the three labels limited / moderate / highly active stay bigger.","tts_text":"فمش كلهم زي الـ copper، ومش كلهم زي الـ scandium… بيختلفوا.","screen_text":"All unreactive like Cu? ✕ · All react strongly with water? ✕"},{"id":"s3l11","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: vanadium, not in the shorts or lessons; tests 'all of them' vs 'varies'). FB: circuit with a V wire and an unlit lamp; YK.checkPause question in the text panel; think ring through the 3 s pause.","tts_text":"طب سلك vanadium في دايرة كهربا… اللمبة هتنور؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"A vanadium wire in a circuit: does the lamp light?","pause_after_s":3},{"id":"s3l12","visual":"[CORE] FB. Lamp lights on cue 'هتنور'; answer slot + YK.rightMark on cue 'conductors'.","tts_text":"أيوه هتنور: كلهم good conductors للـ electricity، والـ vanadium منهم.","screen_text":"Yes ✓ all are good conductors of electricity"},{"id":"s3l13","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title:'The metallic property', line:'Solid, metallic luster, good conductivity · activity varies (Cu < Fe < Sc)', pulse:[{word:'activity', at:cue(s3l13,'activity')}]}). Stage: triptych small.","tts_text":"الخلاصة: الـ metallic property واضحة فيهم، بس الـ activity بتختلف.","screen_text":"Solid, metallic luster, good conductivity · activity varies (Cu < Fe < Sc)"},{"id":"s3l14","visual":"[CORE] SO-WHAT · FB. Blocks of the STRIP sit on a flame bar that glows on cue 'نسخّنهم'. Segment chip out; in the pause: camera push into the PART 4 card.","tts_text":"كلهم solid… طب لازم نسخّنهم قد إيه عشان يسيحوا؟","screen_text":"All solid. How hot before they melt?","pause_after_s":2.5},{"id":"s4l1","style":"curious","visual":"PART 4/6 · te.high-melting-points · objective: Describe the melting and boiling points of the first transition series. · [CORE] Segment card in s3l14's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 4 OF 6', title:'High melting and boiling points', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'High melting and boiling points', never cut) on line start, chip kept to the micro-recap. Line: FB Cr block on the episode THERMOMETER that fills to '1890 °C' (YK.label 72) on cue 'ألف'. RE-HOOK. Book table p.12.","tts_text":"الـ chromium مش بيسيح غير عند ألف وتمنمية وتسعين درجة!","screen_text":"Cr melts at 1890 °C"},{"id":"s4l2","visual":"PREREQ phys.states-melting-boiling [RECAP-PREREQ] (s4l2 + s4l3 ≤ 20 s, reference only) · TP. Prereq YK.chip (link icon) 'States of matter, melting and boiling points'. Stage (no short exists for this prereq; episode model): YK.lattice 4×5 ordered particles labelled 'solid' on cue 'solid' loosen into a flowing group labelled 'liquid' on cue 'liquid'.","tts_text":"فاكرين الـ melting point؟ الدرجة اللي الـ solid بيبقى فيها liquid خلاص.","screen_text":"Melting point: solid → liquid"},{"id":"s4l3","visual":"PREREQ phys.states-melting-boiling [RECAP-PREREQ] TP. Bonds between the particles thicken on cue 'أقوى'; thermometer mark moves up on cue 'بيعلى'. Prereq chip out.","tts_text":"وكل ما الشد بين الـ particles أقوى، الـ melting point بيعلى.","screen_text":"Stronger pull between particles → higher melting point"},{"id":"s4l4","visual":"[CORE] FB DATA TABLE (shot change): 'Melting point °C' column lit (1397, 1680, 1710, 1890, 1247, 1538, 1490, 1492, 1083) on cue 'melting'; a gold line under all values + tag 'all above 1000 °C' on cue 'الألف'. No text-panel headline (the table is full-bleed; the chip carries the title).","tts_text":"بصّوا عمود الـ melting point في الجدول: كلهم فوق الألف درجة.","screen_text":"Melting points: all above 1000 °C"},{"id":"s4l5","visual":"[CORE] FB DATA TABLE: 'Boiling point °C' column lit on cue 'boiling' (3900, 3130, 3530, 2480, 2087, 2800, 3520, 2800, 2582); min 2087 (Mn) and max 3900 (Sc) pulse on cues 'ألفين', 'آلاف'.","tts_text":"والـ boiling point أعلى كمان: من حوالي ألفين، لحد قرب الأربع آلاف.","screen_text":"Boiling points: about 2000 to 3900 °C"},{"id":"s4l6","visual":"[CORE] TP. MISCONCEPTION te.high-melting-points #1: coral tag 'Heavy atoms?' on cue 'تقيلة' (said once, small).","tts_text":"ناس كتير فاكرة إن الـ melting point عالي عشان الـ atoms تقيلة.","screen_text":"Heavy atoms → high melting point? ✕"},{"id":"s4l7","visual":"[CORE] FB split (first-mentioned left): Cu panel: mass '63.5' on cue 'copper', thermometer to '1083 °C' on cue 'ألف'. Right panel Cr empty, same scale.","tts_text":"الـ copper أتقل واحد في الجدول، ويسيح عند حوالي ألف وتمانين بس.","screen_text":"Cu: 63.5 (heaviest) → 1083 °C"},{"id":"s4l8","visual":"[CORE] FB split right panel: Cr mass '52' on cue 'chromium', thermometer to '1890 °C' (taller, gold) on cue 'ألف'. The 'Heavy atoms?' tag gets YK.wrongMark at line end (< 2 s).","tts_text":"والـ chromium أخف منه بكتير، ويسيح عند ألف وتمنمية وتسعين!","screen_text":"Cr: 52 (lighter) → 1890 °C"},{"id":"s4l9","visual":"[CORE] TP. Text row 'Not the mass → the strength of the bond' builds on cues 'mass', 'bond'; stage: two YK.atomDisc with a thick bond line between them that pulses gold on cue 'bond'.","tts_text":"يبقى الـ mass مش هي اللي بتقرّر… اللي بيقرّر قوة الـ bond نفسها.","screen_text":"Not the mass: the strength of the bond"},{"id":"s4l10","visual":"[CORE] PAUSE-AND-PREDICT (NEW pair: Mn and V; melting-point column hidden). Stage split, first-mentioned left: Mn block (mass tag '54.9') on cue 'manganese' | V block ('51') on cue 'vanadium'; YK.checkPause in the text panel; think ring through the 3 s pause.","tts_text":"الـ manganese أتقل من الـ vanadium… يبقى يسيح عند درجة أعلى؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"Mn (54.9) is heavier than V (51). Does Mn melt higher?","pause_after_s":3},{"id":"s4l11","visual":"[CORE] FB split (Mn left, V right, same THERMOMETER scale): V fills to '1710 °C' on cue 'vanadium', Mn to '1247 °C' on cue 'manganese'; answer slot + YK.rightMark. Book table p.12.","tts_text":"لأ: الـ vanadium حوالي ألف وسبعمية، والـ manganese حوالي ألف ومتين وخمسين.","screen_text":"No ✓ V 1710 °C · Mn 1247 °C"},{"id":"s4l12","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title:'High melting and boiling points', line:'High melting and boiling points: a strong bond, not the mass', pulse:[{word:'strong bond', at:cue(s4l12,'bond')}]}). Stage: the two thermometers.","tts_text":"الـ melting والـ boiling points عالية بسبب bond قوي، مش mass كبيرة.","screen_text":"High melting and boiling points: a strong bond, not the mass"},{"id":"s4l13","style":"curious","visual":"[CORE] SO-WHAT · FB. Zoom into the Cr block until its atoms show as the ELECTRON SEA grid (still blurred) on cue 'electrons'. In the pause: camera move into the PART 5 card.","tts_text":"طب أنهي bond ده؟ وأنهي electrons بتبنيه؟","screen_text":"Which bond? Which electrons build it?","pause_after_s":2.5},{"id":"s5l1","style":"curious","visual":"PART 5/6 · te.high-melting-points · objective: Explain the high melting points by the metallic bond. · [CORE] Segment card in s4l13's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 5 OF 6', title:'High melting and boiling points', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'High melting and boiling points', never cut) on line start, chip kept to the micro-recap. Line: FB ELECTRON SEA (sharp now), a '?' over the grid on cue 'ماسك'. RE-HOOK.","tts_text":"إيه اللي ماسك الـ atoms في المعدن بالقوة دي؟","screen_text":"What holds metal atoms together so strongly?"},{"id":"s5l3","visual":"PREREQ bond.metallic-bond [RECAP-PREREQ] (the segment's one recap, ≤ 8 s, reference only) FB (shot change). Prereq YK.chip (link icon) 'Metallic bond' on line start (no short exists for this prereq: the episode ELECTRON SEA is the model): labels 'free electrons' on cue 'free', 'positive ions' on cue 'positive'. Prereq chip out at line end.","tts_text":"فاكرين الـ metallic bond؟ بحر free electrons ماسك الـ positive ions كلها.","screen_text":"Metallic bond: positive ions in a sea of free electrons"},{"id":"s5l4","visual":"[CORE] FB sea: cyan dot density doubles on cue 'تكتر'; the ion grid tightens (spacing −6%) and a 'bond strength' bar rises on cue 'أقوى'.","tts_text":"وكل ما الـ free electrons تكتر، الـ metallic bond بيبقى أقوى.","screen_text":"More free electrons → stronger metallic bond"},{"id":"s5l5","visual":"[CORE] FB split (first-mentioned left): Ca panel: 'Ca: [Ar] 4s^2' (YK.formula 48) + tag 'Z = 20' + 4s box; two pink 4s electrons leave into a thin ELECTRON SEA on cue 'four'. Right panel empty, same scale (s-block contrast, concept summary).","tts_text":"في الـ calcium، electrons الـ four s بس هي اللي بتدخل البحر ده.","screen_text":"Ca: [Ar] 4s² → only 4s electrons in the sea"},{"id":"s5l6","visual":"[CORE] FB split right panel: transition-metal 4s box (pink) + 3d boxes (violet, the episode/unit model); electrons from 4s on cue 'four' and from 3d on cue 'three' join a denser sea. Book p.13 point b.","tts_text":"لكن الـ transition elements؟ بيشارك فيها electrons الـ four s والـ three d سوا.","screen_text":"Transition elements: both 4s and 3d electrons share"},{"id":"s5l7","visual":"[CORE] TP. WORKED EXAMPLE row 'Fe: [Ar] !{4s^2} !{3d^6}' (YK.formula 56, tag 'Z = 26') with '4s' and '3d' turning gold on cues 'four', 'three'. Stage: Fe ELECTRON SEA, dots arrive from both sublevel boxes. No count of how many 3d electrons (book does not give one).","tts_text":"خدوا الـ iron: electrons من الـ four s ومن الـ three d بتنزل البحر.","screen_text":"Fe: [Ar] 4s² 3d⁶ → 4s and 3d electrons in the sea"},{"id":"s5l8","visual":"[CORE] FB sea: the Fe sea is visibly denser than the Ca sea (split returns briefly, Ca left dim) on cue 'metallic' + label 'strong metallic bond'; then heat glow rises under the grid, ions only jiggle until the thermometer is far up; label 'high melting point' on cue 'melting'.","tts_text":"فالـ metallic bond قوي، والمعدن محتاج حرارة كبيرة عشان يسيح… فالـ melting point عالي.","screen_text":"Strong metallic bond → more heat to melt → high melting point"},{"id":"s5l9","visual":"[CORE] TP. MISCONCEPTION te.high-melting-points #2: small coral row 'only 4s electrons' + YK.wrongMark on cue 'غلط' (< 2 s); the 3d boxes in the stage re-pulse violet.","tts_text":"فاللي يقول electrons الـ four s بس هي اللي بتعمل الـ bond… غلط.","screen_text":"Only 4s electrons form the bond? ✕"},{"id":"s5l10","visual":"[CORE] FB split (first-mentioned left): K panel 'K: [Ar] 4s^1' (YK.formula 56, tag 'Z = 19') + one 4s electron on cue 'four' | V panel 'V: [Ar] 4s^2 3d^3' (tag 'Z = 23') appears grey (lit next line).","tts_text":"الـ potassium عنده بس electron واحد، في الـ four s بتاعته.","screen_text":"K: [Ar] 4s¹"},{"id":"s5l11","visual":"[CORE] PAUSE-AND-PREDICT (NEW pair: K vs V, not in the shorts or lessons; no melting-point numbers shown, K is not in the book table). FB split: V panel lights on cue 'vanadium' (4s + 3d boxes); YK.checkPause in the text panel; think ring through the 3 s pause.","tts_text":"والـ vanadium فيه four s و three d… مين الـ bond أقوى؟ وقّفوا وفكّروا. <long pause>","screen_text":"K or V: which has the stronger bond?","pause_after_s":3},{"id":"s5l12","visual":"[CORE] FB split: V sea fills from both boxes on cues 'four', 'three', denser than K's; answer slot + YK.rightMark on cue 'أقوى'.","tts_text":"الـ vanadium: electrons الـ four s والـ three d بيشاركوا، فالـ metallic bond أقوى.","screen_text":"V ✓ both 4s and 3d electrons share → stronger metallic bond"},{"id":"s5l13","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title:'High melting and boiling points', line:'Strong metallic bond: both 4s and 3d electrons share', formula:'4s + 3d → metallic bond', pulse:[{word:'4s and 3d', at:cue(s5l13,'four')}, {word:'metallic bond', at:cue(s5l13,'metallic')}]}). Book p.13 point b wording.","tts_text":"الخلاصة: electrons الـ four s والـ three d بيشاركوا، فالـ metallic bond قوي.","screen_text":"Strong metallic bond: both 4s and 3d electrons share"},{"id":"s5l14","visual":"[CORE] SO-WHAT · FB. The big-question tag (top-right) re-appears: its melting half gets a small ✓ on cue 'تسيح', the density half pulses on cue 'تقيلة'. Segment chip out.","tts_text":"عرفنا ليه صعب تسيح… طب ليه تقيلة كده؟","screen_text":"Hard to melt: solved. Why so dense?","pause_after_s":1},{"id":"m2l1","visual":"[CORE] MID-EPISODE RECAP 2 (~9:00) · FB. YK.flow({rtl:false}) row continues the m1 chain (nodes 1-2 small, dim, on the left); header 'So far'. Node 3 'All solid · activity varies' on cue 'solid'.","tts_text":"نلم تاني: كلهم معادن solid، بس الـ activity بتختلف.","screen_text":"All solid · activity varies"},{"id":"m2l2","visual":"[CORE] FB flow: arrow + node 4 'High melting points' (sub '4s + 3d electrons share') on cue 'melting'; nodes 1-4 glow once. In the pause: camera move from node 1 and node 2 (both pulse) into the PART 6 card.","tts_text":"والـ melting point عالي، عشان electrons الـ four s والـ three d بتشارك.","screen_text":"High melting points: 4s + 3d electrons share","pause_after_s":2.5},{"id":"s6l1","style":"curious","visual":"PART 6/6 · te.density-trend · objective: Explain why the density increases with atomic number. · [CORE] Segment card in m2l2's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 6 OF 6', title:'Density increases with atomic number', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Density increases with atomic number', never cut) on line start, chip kept to the micro-recap. Line: FB split (first-mentioned left): Cr ATOM | Cu ATOM, identical circles (r 1.17) with tags '1.17'; '= ?' between them on cue 'density'. RE-HOOK.","tts_text":"الـ chromium والـ copper نفس الحجم بالظبط… يبقى الـ density واحدة؟","screen_text":"Cr and Cu: same size (1.17). Same density?"},{"id":"s6l2","visual":"PREREQ phys.density [RECAP-PREREQ] (≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Density'. Formula 'Density = mass / volume' (YK.formula 56) builds on cues 'mass', 'volume'; stage: one empty CUBE '1 cm³' on cue 'المكعب'.","tts_text":"فاكرين الـ density؟ الـ mass على الـ volume، كتلة السنتي المكعب.","screen_text":"Density = mass / volume (g/cm³)"},{"id":"s6l3","visual":"[CORE] FB DATA TABLE (shot change): 'Density g/cm³' column lit on cue 'density'; gold arrow down the column on cue 'وبتزيد'; first (3.10, Sc) and last (8.92, Cu) values full and pulsing at line end; the middle values stay at 40% (Fe/Co are the s6l10 predict, Ti/Ni the z12 recall). Gold tag 'increases with atomic number' beside the column (no text panel). Book p.13 point c.","tts_text":"الكتاب بيقول: أغلبهم الـ density عالية، وبتزيد كل ما الـ atomic number يزيد.","screen_text":"Most of them have high density, which increases with atomic number"},{"id":"s6l4","visual":"[CORE] TP. WORKED EXAMPLE (book table rows Cr, Cu; lesson-te.density-trend's pair, same CUBE model). Text rows 'Cr: 52 · radius 1.17' on cue 'chromium', 'Cu: 63.5 · radius 1.17' on cue 'copper'; '63.5' gold on cue 'أكبر'.","tts_text":"نرجع للـ chromium والـ copper: الـ atomic mass بتاعة الـ copper أكبر بكتير.","screen_text":"Atomic mass: Cr 52 · Cu 63.5"},{"id":"s6l5","visual":"[CORE] FB split (Cr left, Cu right): two CUBES with the same number of same-size ATOM discs; Cu discs darker (heavier) on cue 'أكبر'; mass readouts rise on cue 'mass'.","tts_text":"نفس الحجم، وكتلة أكبر… يعني mass أكتر في كل سنتي مكعب.","screen_text":"Same size + more mass → more mass in each cm³"},{"id":"s6l6","visual":"[CORE] FB split: density readouts '7.19' on cue 'chromium', '8.92' on cue 'copper' (YK.label 64); a gold ↑ on cue 'زادت'. Book table p.12.","tts_text":"الـ chromium سبعة وشوية، والـ copper حوالي تسعة: الـ density زادت.","screen_text":"Density: Cr 7.19 → Cu 8.92 g/cm³"},{"id":"s6l7","visual":"[CORE] TP. Rule row builds on cues 'mass' ('Mass ↑'), 'size' ('size relatively constant'), 'density' ('→ density ↑'). Stage: CUBE whose discs darken step by step Cr → Cu (6 steps) while their size stays fixed.","tts_text":"ودي القاعدة: الـ mass بتزيد، والـ atomic size ثابت نسبياً، فالـ density بتزيد.","screen_text":"Mass ↑, size relatively constant → density ↑"},{"id":"s6l8","visual":"[CORE] FB (full-bleed connection shot): the Part 1 mass bars (left) and Part 2 flat circle row (centre) slide in and merge into the density column (right); the gold link icon from s2l16 snaps closed on cue 'اتقابلوا'.","tts_text":"شايفين؟ الـ atomic mass والـ atomic radius اللي فاتوا، اتقابلوا في الـ density هنا.","screen_text":"Atomic mass ↑ + atomic radius constant → density ↑"},{"id":"s6l9","visual":"[CORE] TP. MISCONCEPTION te.density-trend #1: small coral tag 'atoms get much smaller?' + YK.wrongMark on cue 'لأ' (< 2 s); the flat circle row (Cr → Cu, k = 45) re-pulses with label 'size nearly constant'. [v5 facts fix: coral tag scoped 'From Cr to Cu: atoms get much smaller?'; the refutation holds only for Cr → Cu (Sc 1.44 → V 1.22 do shrink).]","tts_text":"ناس كتير فاكرة إن من الـ chromium للـ copper، الـ density بتزيد عشان الـ atoms بتصغر… لأ، الحجم ثابت.","screen_text":"From Cr to Cu, density rises because atoms get much smaller? ✕"},{"id":"s6l10","visual":"[CORE] PAUSE-AND-PREDICT (NEW pair: Fe vs Co, not in the shorts or lessons; density column hidden during the question). FB split: Fe CUBE | Co CUBE, same disc size, masses shown; YK.checkPause in the text panel; think ring through the 3 s pause.","tts_text":"الـ iron والـ cobalt نفس الـ radius… مين الـ density أعلى؟ وقّفوا ثانية وفكّروا. <long pause>","screen_text":"Fe (55.9) and Co (58.9), same radius 1.16: which has the higher density?","pause_after_s":3},{"id":"s6l11","visual":"[CORE] FB split: Co cube discs darken on cue 'mass'; readouts '7.87' / '8.70' + YK.rightMark on cue 'density'. Book table p.12.","tts_text":"الـ cobalt: الـ mass أكبر في نفس الحجم، فالـ density أعلى.","screen_text":"Co ✓ more mass, same size (Fe 7.87 · Co 8.70 g/cm³)"},{"id":"s6l12","visual":"[CORE] MICRO-RECAP · TP. YK.takeaway({title:'Density increases with atomic number', line:'The atomic size is relatively constant with increasing atomic mass', formula:'Density = mass / volume', pulse:[{word:'relatively constant', at:cue(s6l12,'ثابت')}, {word:'atomic mass', at:cue(s6l12,'mass')}]}). Book p.13 point c wording.","tts_text":"فالـ density بتزيد مع الـ atomic number: الـ atomic size ثابت، والـ mass بتزيد.","screen_text":"Density increases with atomic number: the atomic size is relatively constant with increasing atomic mass"},{"id":"s6l13","visual":"[CORE] SO-WHAT · FB. Camera pulls out from the CUBE to an empty flow row. Segment chip out.","tts_text":"يلا نلم الحلقة كلها في سلسلة واحدة.","screen_text":"The whole unit in one chain","pause_after_s":1},{"id":"z1","visual":"[CORE] CLOSING SUMMARY · FB. Chain in book order, explicit node x/y (5 nodes do not fit one row at ≥ 32 px): row A y 330: node 1 (x 96–620), node 2 (x 700–1224), node 3 (x 1300–1824); row B y 640: node 4 (x 400–1000), node 5 (x 1100–1700); left → right, YK.flow node size 36, labels ≤ 4 words + sub. Node 1 'Atomic mass ↑' (sub 'Ni abnormal') on cue 'atomic'.","tts_text":"الـ atomic mass بتزيد بالتدريج، والـ nickel abnormal بسبب الـ isotopes بتاعته.","screen_text":"Atomic mass ↑ gradually · Ni abnormal (isotopes)"},{"id":"z2","visual":"[CORE] FB flow: arrow + node 2 'Atomic radius nearly constant' (sub 'two opposite factors') on cue 'opposite'.","tts_text":"والـ opposite factors بيخلّوا الـ atomic radius تقريباً ثابت.","screen_text":"Two opposite factors → atomic radius nearly constant"},{"id":"z3","visual":"[CORE] FB flow: arrow + node 3 'Metallic property' (sub 'activity varies') on cue 'solid'.","tts_text":"وكلهم معادن solid بتلمع وبتوصّل، والـ activity بس اللي بتختلف.","screen_text":"All solid · activity varies"},{"id":"z4","visual":"[CORE] FB flow: arrow (row A → row B) + node 4 'High melting points' (sub '4s + 3d metallic bond') on cue 'metallic'.","tts_text":"والـ four s والـ three d في الـ metallic bond، فالـ melting point عالي.","screen_text":"4s + 3d in the metallic bond → high melting points"},{"id":"z5","visual":"[CORE] FB flow: node 5 'Density ↑' (sub 'more mass, same size') on cue 'density', fed by two custom curved gold YK.arrows from node 1 (on cue 'mass') and node 2 (on cue 'size') drawn above/around row A (not flow edges: they would cross nodes); the chain glows once.","tts_text":"والـ mass بتزيد والـ atomic size ثابت، فالـ density بتطلع.","screen_text":"Mass ↑ + size constant → density ↑"},{"id":"z6","visual":"[CORE] BIG QUESTION ANSWERED (1/2) · FB split (the cold-open pair): left Cu CUBE vs Sc CUBE readouts; the gold tag 'Why such high density and melting points?' top-centre; its density half ✓ on cue 'density'. [v5 facts fix: the voice now answers for this pair only (Cu: more mass in a smaller atom, book radii Sc 1.44 / Cu 1.17); do not draw the Sc cube with the same atom count/size as Cu.]","tts_text":"فإجابة سؤالنا: الـ copper فيه mass أكبر في atom أصغر، فالـ density أعلى بكتير.","screen_text":"High density: Cu has more mass in a smaller atom"},{"id":"z7","visual":"[CORE] BIG QUESTION ANSWERED (2/2): the cold-open Fe thermometer + ELECTRON SEA behind it; melting half of the tag ✓ on cue 'metallic'.","tts_text":"والـ melting point عالي، عشان الـ metallic bond قوي جداً.","screen_text":"High melting points: a strong metallic bond"},{"id":"z8","visual":"[CORE] RECALL 1/3 (Part 2, book 'give reasons' form, Evaluation Q7.4 p.27) · TP. YK.checkPause in the text panel; stage: flat circle row Cr → Cu; think ring through the 3 s pause.","tts_text":"سؤال: ليه الـ atomic radius تقريباً ثابت من الـ chromium للـ copper؟ وقّفوا وفكّروا. <long pause>","screen_text":"Give reasons: the atomic radius is nearly constant from Cr to Cu.","pause_after_s":3},{"id":"z9","visual":"[CORE] TP. Answer rows build on cues 'nuclear', 'repulsion' + tug-of-war ATOM + YK.rightMark on cue 'بتكبّر'.","tts_text":"الـ effective nuclear charge بيزيد فيصغّر، والـ repulsion في الـ three d بتكبّر.","screen_text":"Effective nuclear charge ↑ (smaller) · 3d repulsion ↑ (larger) ✓"},{"id":"z10","visual":"[CORE] RECALL 2/3 (Parts 4–5, book 'give reasons' form, Evaluation Q7.5 p.27) · FB (breaks a 4-text-panel run z8–z11): full-width Cr block on the THERMOMETER at 1890 °C, ELECTRON SEA blurred behind; YK.checkPause question top-left (x 96–900); think ring through the 3 s pause.","tts_text":"تاني سؤال: ليه الـ transition elements الـ melting والـ boiling points عالية؟ وقّفوا وفكّروا. <long pause>","screen_text":"Give reasons: transition elements have high melting and boiling points.","pause_after_s":3},{"id":"z11","visual":"[CORE] TP. Answer row builds on cues 'metallic', 'four', 'three' + ELECTRON SEA fed from both boxes + YK.rightMark.","tts_text":"عشان الـ metallic bond قوي: electrons الـ four s والـ three d بتشارك فيه.","screen_text":"Strong metallic bond: both 4s and 3d electrons share ✓"},{"id":"z12","visual":"[CORE] RECALL 3/3 (Parts 1, 2, 6; NEW case Ti vs Ni, not in the shorts or lessons) · FB split: Ti ATOM (r 1.32, mass 47.9) | Ni ATOM (r 1.15, mass 58.7) on cues 'titanium', 'nickel'; YK.checkPause in the text panel; think ring through the 3 s pause.","tts_text":"الـ titanium أخف وأكبر، والـ nickel أتقل وأصغر… مين الـ density أعلى؟ وقّفوا وفكّروا. <long pause>","screen_text":"Ti: lighter, larger · Ni: heavier, smaller. Which has the higher density?","pause_after_s":3},{"id":"z13","visual":"[CORE] FB split: CUBES fill; readouts '4.42' / '8.90' on cue 'density' + YK.rightMark. Book table p.12.","tts_text":"الـ nickel: mass أكبر في atom أصغر، فالـ density أعلى بكتير.","screen_text":"Ni ✓ more mass in a smaller atom (Ti 4.42 · Ni 8.90 g/cm³)"},{"id":"z14","visual":"[TRIM-IF-OVER 15:00] TEASER (labelled last line only) · FB STRIP; label 'Next episode:' (Cairo 800 40, textDim) + 'Magnetic properties and catalytic activity' (Cairo 1000 64). No subscribe. 0.8 s tail.","tts_text":"الحلقة الجاية: الـ magnetic properties، والـ catalytic activity بتاعتهم.","screen_text":"Next episode: Magnetic properties and catalytic activity"}],"logline":"Copper is almost three times as dense as scandium, and iron needs more than 1500 °C to melt. Six parts in the book's order (pp.12-13, the book's table for illustration): atomic mass and the nickel anomaly, the nearly constant atomic radius from two opposite factors, the metallic property and its varying activity, high melting and boiling points from a metallic bond built by both 4s and 3d electrons, and density rising because mass grows while size stays nearly 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معادن في صف واحد من الـ scandium لحد\nالـ copper في الآخر\nحتة copper أتقل حوالي تلات مرات من حتة\nscandium بنفس الحجم\nوالـ iron عشان يسيح محتاج أكتر من ألف\nوخمسمية درجة\nليه الـ density عالية كده والـ melting\npoint عالي كده\nالحلقة دي عن الـ general properties الـ\nmass والـ radius والـ metallic property\nبتاعتهم\nالـ nickel بعد الـ cobalt في الجدول يبقى\nأتقل منه صح\nالكتاب بيقول الـ atomic mass بتزيد\nبالتدريج كل ما الـ atomic number يزيد\nبس بصّوا هنا الـ cobalt والـ nickel\nالاتنين حوالي تسعة وخمسين\nوالـ nickel مع إنه بعده أخف شوية فالكتاب\nبيقول إنه abnormal هنا\nناس كتير بتقول أكيد غلطة مطبعية في الجدول\nلأ مش غلطة\nفاكرين الـ isotopes نفس الـ element بس عدد\nالـ neutrons مختلف\nوالـ atomic mass اللي في الجدول متوسط الـ\nisotopes دي كلها\nوالـ nickel عنده خمس stable isotopes\nوكتلته متوسط الخمسة دول\nوأغلب الـ atoms بتاعة الـ nickel من النوع\nالخفيف nickel تمانية وخمسين\nفالمتوسط بينزل تحت الـ cobalt حتى لو الـ\nprotons أكتر\nلو أغلب الـ nickel كان nickel ستين هيفضل\nأخف من الـ cobalt وقّفوا وفكّروا\nلأ المتوسط كان هيعدّي الـ cobalt يعني\nالخليط هو اللي بيفرق\nالخلاصة الـ atomic mass بتزيد بالتدريج\nوالـ nickel abnormal عشان الـ stable\nisotopes بتاعته\nالكتلة بتزيد طب حجم الـ atom بيزيد معاها\nمن الـ chromium للـ copper زوّدنا خمس\nprotons المفروض الـ atom يصغر صح\nفاكرين الـ period التالت من الـ sodium للـ\nchlorine الـ atomic radius بيقل بوضوح\nعشان الـ protons بتزيد والشد ناحية الـ\nnucleus بيقوى\nبس هنا الـ atomic radius بيتغير شوية ومن\nالـ chromium للـ copper تقريبا ثابت\nيعني مش بيقل جامد زي الـ period التالت طب\nليه\nالكتاب بيسميهم opposite factors واحد\nبيصغّر الـ atom والتاني بيكبّره\nأول factor من الـ scandium للـ chromium\nالـ effective nuclear charge بيزيد\nومع زيادة الـ electrons شد الـ nucleus\nعليهم بيزيد فالـ atomic radius بيقل\nتاني factor الـ three d بتتملي والـ\nelectrons اللي فيها بتزق بعض\nوالـ repulsion بين الـ electrons دي بتوسّع\nالـ atom فالـ atomic radius بيزيد\nالـ opposite factors بيلغوا بعض تقريبا\nفالـ atomic radius بيفضل ثابت نسبيا\nوعشان أحجامهم قريبة كده بيستخدموهم في عمل\nالـ alloys مع بعض\nالـ iron والـ nickel ينفع يدخلوا مع بعض في\nalloy بسهولة وقّفوا ثانية وفكّروا\nأيوه الـ atomic radius بتاعهم تقريبا واحد\nفيدخلوا مكان بعض بسهولة\nالخلاصة الـ nucleus بيشد والـ repulsion\nبتزق فالـ atomic radius تقريبا ثابت\nيعني الكتلة بتزيد والحجم ثابت خلّوا\nالاتنين دول في دماغكم\nنلم اللي فات الـ atomic mass بتزيد بس الـ\nnickel abnormal فيها\nوالـ atomic radius تقريبا ثابت عشان الـ\nopposite factors دول\nمعادن من نفس الصف بس واحد بيتفاعل مع المية\nبعنف وواحد بالعافية\nنبدأ باللي بيجمعهم كلهم solid في الظروف\nالعادية\nوكلهم بيلمعوا لمعة المعادن دي اسمها\nmetallic luster في الكتاب\nوكلهم عندهم good conductivity للـ heat\nوالـ electricity كمان\nبس الـ activity بتاعتهم هنا بقى بيختلفوا\nجامد\nفاكرين الـ activity series المعدن النشيط\nأوي بيطرد الـ hydrogen من المية\nوالـ copper الـ chemical activity بتاعته\nlimited مش بيتفاعل بسهولة\nوالـ iron في النص moderate بيصدّي لو اتساب\nفي الهوا\nوآخرهم الـ scandium ده highly active بيطرد\nالـ hydrogen من المية بقوة\nفمش كلهم زي الـ copper ومش كلهم زي الـ\nscandium بيختلفوا\nطب سلك vanadium في دايرة كهربا اللمبة\nهتنور وقّفوا ثانية وفكّروا\nأيوه هتنور كلهم good conductors للـ\nelectricity والـ vanadium منهم\nالخلاصة الـ metallic property واضحة فيهم\nبس الـ activity بتختلف\nكلهم solid طب لازم نسخّنهم قد إيه عشان\nيسيحوا\nالـ chromium مش بيسيح غير عند ألف وتمنمية\nوتسعين درجة\nفاكرين الـ melting point الدرجة اللي الـ\nsolid بيبقى فيها liquid خلاص\nوكل ما الشد بين الـ particles أقوى الـ\nmelting point بيعلى\nبصّوا عمود الـ melting point في الجدول\nكلهم فوق الألف درجة\nوالـ boiling point أعلى كمان من حوالي\nألفين لحد قرب الأربع آلاف\nناس كتير فاكرة إن الـ melting point عالي\nعشان الـ atoms تقيلة\nالـ copper أتقل واحد في الجدول ويسيح عند\nحوالي ألف وتمانين بس\nوالـ chromium أخف منه بكتير ويسيح عند ألف\nوتمنمية وتسعين\nيبقى الـ mass مش هي اللي بتقرّر اللي\nبيقرّر قوة الـ bond نفسها\nالـ manganese أتقل من الـ vanadium يبقى\nيسيح عند درجة أعلى وقّفوا ثانية وفكّروا\nلأ الـ vanadium حوالي ألف وسبعمية والـ\nmanganese حوالي ألف ومتين وخمسين\nالـ melting والـ boiling points عالية بسبب\nbond قوي مش mass كبيرة\nطب أنهي bond ده وأنهي electrons بتبنيه\nإيه اللي ماسك الـ atoms في المعدن بالقوة\nدي\nفاكرين الـ metallic bond بحر free\nelectrons ماسك الـ positive ions كلها\nوكل ما الـ free electrons تكتر الـ\nmetallic bond بيبقى أقوى\nفي الـ calcium electrons الـ four s بس هي\nاللي بتدخل البحر ده\nلكن الـ transition elements بيشارك فيها\nelectrons الـ four s والـ three d سوا\nخدوا الـ iron electrons من الـ four s ومن\nالـ three d بتنزل البحر\nفالـ metallic bond قوي والمعدن محتاج حرارة\nكبيرة عشان يسيح فالـ melting point عالي\nفاللي يقول electrons الـ four s بس هي اللي\nبتعمل الـ bond غلط\nالـ potassium عنده بس electron واحد في الـ\nfour s بتاعته\nوالـ vanadium فيه four s و three d مين الـ\nbond أقوى وقّفوا وفكّروا\nالـ vanadium electrons الـ four s والـ\nthree d بيشاركوا فالـ metallic bond أقوى\nالخلاصة electrons الـ four s والـ three d\nبيشاركوا فالـ metallic bond قوي\nعرفنا ليه صعب تسيح طب ليه تقيلة كده\nنلم تاني كلهم معادن solid بس الـ activity\nبتختلف\nوالـ melting point عالي عشان electrons الـ\nfour s والـ three d بتشارك\nالـ chromium والـ copper نفس الحجم بالظبط\nيبقى الـ density واحدة\nفاكرين الـ density الـ mass على الـ volume\nكتلة السنتي المكعب\nالكتاب بيقول أغلبهم الـ density عالية\nوبتزيد كل ما الـ atomic number يزيد\nنرجع للـ chromium والـ copper الـ atomic\nmass بتاعة الـ copper أكبر بكتير\nنفس الحجم وكتلة أكبر يعني mass أكتر في كل\nسنتي مكعب\nالـ chromium سبعة وشوية والـ copper حوالي\nتسعة الـ density زادت\nودي القاعدة الـ mass بتزيد والـ atomic\nsize ثابت نسبيا فالـ density بتزيد\nشايفين الـ atomic mass والـ atomic radius\nاللي فاتوا اتقابلوا في الـ density هنا\nناس كتير فاكرة إن من الـ chromium للـ\ncopper الـ density بتزيد عشان الـ atoms\nبتصغر لأ الحجم ثابت\nالـ iron والـ cobalt نفس الـ radius مين\nالـ density أعلى وقّفوا ثانية وفكّروا\nالـ cobalt الـ mass أكبر في نفس الحجم فالـ\ndensity أعلى\nفالـ density بتزيد مع الـ atomic number\nالـ atomic size ثابت والـ mass بتزيد\nيلا نلم الحلقة كلها في سلسلة واحدة\nالـ atomic mass بتزيد بالتدريج والـ nickel\nabnormal بسبب الـ isotopes بتاعته\nوالـ opposite factors بيخلّوا الـ atomic\nradius تقريبا ثابت\nوكلهم معادن solid بتلمع وبتوصّل والـ\nactivity بس اللي بتختلف\nوالـ four s والـ three d في الـ metallic\nbond فالـ melting point عالي\nوالـ mass بتزيد والـ atomic size ثابت فالـ\ndensity بتطلع\nفإجابة سؤالنا الـ copper فيه mass أكبر في\natom أصغر فالـ density أعلى بكتير\nوالـ melting point عالي عشان الـ metallic\nbond قوي جدا\nسؤال ليه الـ atomic radius تقريبا ثابت من\nالـ chromium للـ copper وقّفوا وفكّروا\nالـ effective nuclear charge بيزيد فيصغّر\nوالـ repulsion في الـ three d بتكبّر\nتاني سؤال ليه الـ transition elements الـ\nmelting والـ boiling points عالية وقّفوا\nوفكّروا\nعشان الـ metallic bond قوي electrons الـ\nfour s والـ three d بتشارك فيه\nالـ titanium أخف وأكبر والـ nickel أتقل\nوأصغر مين الـ density أعلى وقّفوا وفكّروا\nالـ nickel mass أكبر في atom أصغر فالـ\ndensity أعلى بكتير\nالحلقة الجاية الـ magnetic properties والـ\ncatalytic activity بتاعتهم","countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"series_id":"chem-s3-en.ch1#sessions","episode_no":4,"episode_count":9,"lessons":["chem-s3-en.lesson-atom.isotopes","chem-s3-en.lesson-bond.metallic-bond","chem-s3-en.lesson-chem.activity-series","chem-s3-en.lesson-chem.metal-properties","chem-s3-en.lesson-phys.density","chem-s3-en.lesson-phys.states-melting-boiling","chem-s3-en.lesson-pt.atomic-radius-trend","chem-s3-en.lesson-te.atomic-mass-trend","chem-s3-en.lesson-te.atomic-radius","chem-s3-en.lesson-te.density-trend","chem-s3-en.lesson-te.high-melting-points","chem-s3-en.lesson-te.metallic-properties"]},{"id":"chem-s3-en.video-episode-te-magnetism-catalysis","kind":"episode","version":4,"ord":307,"content_lang":"ar-EG","primary_concept_id":"te.magnetic-properties","concepts":[{"concept_id":"te.magnetic-properties","role":"primary"},{"concept_id":"te.catalysis-examples","role":"secondary"},{"concept_id":"te.catalytic-activity","role":"secondary"},{"concept_id":"te.magnetic-moment-from-config","role":"secondary"}],"title":"Magnetic properties and catalytic activity","payload":{"title":"Magnetic properties and catalytic activity","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"16:9","format":"episode","script":[{"id":"c1","visual":"[CORE] COLD OPEN · FB. EPISODE MODELS (kit-checked, reuse in every part, E11): (a) MAGNET = YK.magnet({type:'horseshoe'}) + YK.magneticSample hanging sample tube (neutral steel powder, never a coloured powder: G45; label = the sample's name; ALWAYS tag:false until s1l5 names 'paramagnetic', because the kit prints 'paramagnetic'/'diamagnetic' itself when pull > 0.3); attracted = the tube swings IN (unpaired > 0, kit gold arrow), repelled = it swings OUT a little (unpaired 0; add a small coral arrow, the kit draws none). (b) 3d BOXES = YK.electronBoxes in the KIT/te-configuration colours (↑ cyan, ↓ pink, style-global palette; arrows are never re-coloured); UNPAIRED electrons = gold box highlight (`highlight:[…]`), from s1l4 to the end; a 4s box = a separate electronBoxes({boxes:1, label:'4s'}) on the left; a mono 'unpaired: n' counter under the boxes. Fill by count (5 ↑ first, then ↓ into box 1, 2, … = Hund, matches the book table); removal = lower the count (whole electrons). (c) SPIN = custom: YK.dot electron + a circular arrow + a small cyan field loop (ellipse) around it; two opposite spins = two loops that shrink to grey. (d) ENERGY PROFILE = YK.energyProfile({labels:{y:'Potential energy', x:'Progress of reaction', reactants:'2H_2O_2', products:'2H_2O + O_2', ea:'Activation energy without catalyst', ea2:'Activation energy with catalyst', dH:'Net energy released', catalysed:'with MnO_2'}, colors:{curve:'#FF7A6B' (coral, uncatalysed), curve2:'#2DE2E6' (cyan, catalysed, kit dashes)}}) (book fig 1-3; no short exists for kin.activation-energy, so this kit model is the reference). (e) SURFACE = YK.surface({metal:'Fe'}) with kit molecules (N2, H2 only; no H2O2/SO2/oil molecules in the kit), kit cyan dashed surface bonds, `stretch` = bond weakening. (f) EQUATION rows = YK.formula ≥ 56, conditions syntax '->[over|under]' (one-way arrow, book style). (g) PREDICT = English question in the text panel (YK.para Cairo 800 44, ≤ 2 lines) + YK.thinkRing on the stage from the «فكّروا» cue to the answer line (add <script src=\"../../../../assets/video-kit/lib/short.js\"> to page.html: the template does not load it); the answer line stamps ONE YK.rightMark. (h) MOMENT METER = YK.momentMeter (0–5 dial, label 'unpaired e^-'; label 'pull' in Part 1 before the term). (i) Micro-recaps = YK.takeaway centred card (default w 1180) over the dimmed stage (counts as a full-frame shot, not text panel). Shot: frame 0 already complete (L7): MAGNET + the hanging sample labelled 'iron compound' at rest + headline 'An iron compound near a strong magnet' (Cairo 1000 64, text panel) on screen at t = 0, drift ≤ 2%; the tube swings in on cue 'بيتشد' + 'pulled in' (gold, Cairo 800 48). Book p.13: most compounds of the transition elements are paramagnetic.","tts_text":"حطّوا شوية من compound فيه iron، جنب magnet قوي… بيتشد ناحيته.","screen_text":"An iron compound near a strong magnet: pulled in"},{"id":"c2","visual":"[CORE] FB split (E7, first-mentioned left, identical scale): left the iron sample (pulled in), right a second YK.magneticSample (unpaired:0, same neutral powder, tag:false) labelled 'zinc compound' on cue 'zinc', swings out slightly on cue 'بيتزق' (small coral arrow). Book p.14 (Zn d¹⁰ diamagnetic).","tts_text":"وحطّوا compound فيه zinc… بيتزق بعيد، حاجة صغيرة خالص.","screen_text":"A zinc compound: pushed away, slightly"},{"id":"c3","visual":"[CORE] FB (shot change). Custom reactor (YK.roundRect vessel in kit steel colours, window; no kit primitive for a reactor) with a pile of grey iron granules (discs) on cue 'iron'; N2/H2 molecules (YK.molecule) bubble through faster on cue 'بيسرّعوا'; the pile stays the same size + mono tag 'mass: same' on cue 'بيخلصوا'; label 'ammonia' on cue 'ammonia'. Book p.15 (Haber-Bosch).","tts_text":"وفي مصنع الـ ammonia، شوية iron بيسرّعوا التفاعل… ومش بيخلصوا.","screen_text":"Iron in the ammonia plant: faster, not used up"},{"id":"c4","style":"curious","visual":"[CORE] BIG QUESTION · FB. Previous shots dim to 30%; card centred (Cairo 1000 84, 2 lines, 6 words) 'Why pulled in?' on line start, 'Why ideal catalysts?' on cue 'ideal'; held through the pause, then shrinks to a gold tag top-right (returns in z6/z7).","tts_text":"طب ليه بيتشدوا للـ magnet؟ وليه هما ideal catalysts بالشكل ده؟","screen_text":"Why pulled in? Why ideal catalysts?","pause_after_s":1},{"id":"t1","visual":"[CORE] TITLE CARD (≤ 4 s from line start). YK.titleCard({title:'Magnetic properties and catalytic activity', chip:'Unit 5', subtitle:'Chapter 1: Transition Elements'}) Cairo 1000 ≤ 120; parts row under it (2 columns, YK.para Cairo 800 32, maxWidth 800): 1 Paramagnetic and diamagnetic substances · 2 Unpaired electrons and magnetic moment: the book's table · 3 Unpaired electrons and magnetic moment: from the compound · 4 Catalytic activity of transition elements: the energy profile · 5 Catalytic activity of transition elements: the reason · 6 Nickel, iron and V₂O₅ as catalysts: nickel and iron · 7 Nickel, iron and V₂O₅ as catalysts: V₂O₅. Then camera move (1.2 s, no fade) onto item 1, which grows into the PART 1 card.","tts_text":"الحلقة دي عن الـ magnetic properties، والـ catalytic activity بتاعتهم.","screen_text":"Magnetic properties and catalytic activity","pause_after_s":2.5},{"id":"s1l1","style":"curious","visual":"PART 1/7 · te.magnetic-properties · objective: Distinguish paramagnetic and diamagnetic substances by their electrons. · [CORE] Segment card in t1's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 1 OF 7', title:'Paramagnetic and diamagnetic substances', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Paramagnetic and diamagnetic substances', never cut) on line start, chip kept to the micro-recap. Line: FB MAGNET with both samples (iron left, zinc right; tag:false) re-run their swings on cues 'بتتشد', 'بتتزق'; a '?' between them. RE-HOOK.","tts_text":"نفس الـ magnet: حاجة بتتشد، وحاجة بتتزق… ليه؟","screen_text":"Same magnet: one pulled in, one pushed away. Why?"},{"id":"s1l2","visual":"PREREQ phys.magnetic-field [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · FB. Prereq YK.chip (link icon) 'Magnets and magnetic fields' under the segment chip. SAME MODEL as video-short-phys.magnetic-field (check its page for magnet type/colours): YK.magnet field lines (field 0 → 1) on cue 'magnetic'; label 'region' on cue 'region'. Prereq chip out at line end.","tts_text":"فاكرين الـ magnetic field؟ الـ region حوالين الـ magnet، اللي قوته بتأثر فيها.","screen_text":"Magnetic field: the region around a magnet where its force acts"},{"id":"s1l3","visual":"[CORE] FB (shot change: YK.zoomThrough with draw fns, from: the sample tube → to: one electron). SPIN model on cue 'electron'; the circular arrow turns on cue 'spin' (after tts fix; until then 'بيلف'); a small field loop grows on cue 'magnetic'. Book p.13: 'forms a magnetic field due to its spinning'.","tts_text":"والـ electron بالـ spin بتاعه بيعمل magnetic field صغير.","screen_text":"Electron spin makes a small magnetic field"},{"id":"s1l4","visual":"[CORE] TP. One orbital box YK.electronBoxes({boxes:1, electrons:1, highlight:[0]}) (↑ cyan, box gold) on cue 'unpaired'; label 'unpaired electron (↑)'; its SPIN loop stays and pulses on cue 'بيفضل'. Gold box = unpaired from here to the end (E11).","tts_text":"لو الـ electron ده unpaired، الـ field بتاعه بيفضل موجود.","screen_text":"Unpaired electron (↑) in an orbital: its field stays"},{"id":"s1l5","visual":"[CORE] TP. NEW TERM 1 'paramagnetic' (Cairo 1000 72, gold) on cue 'paramagnetic'; stage: MAGNET, the iron sample swings in on the same cue 'paramagnetic' (kit tag now on: it prints 'paramagnetic' in gold, so it must not move earlier).","tts_text":"والمادة اللي فيها unpaired electrons كده، اسمها paramagnetic في الكتاب.","screen_text":"Paramagnetic"},{"id":"s1l6","visual":"[CORE] TP. The segment's one definition card YK.termCard({term:'Paramagnetic substance', def:'Attracts to the external magnetic field, due to the presence of unpaired electrons.', keys:['attracts','unpaired electrons']}) on cue 'substance' (book p.13 wording, typo 'unpaid' fixed); keys pulse on cues 'بتتشد' and 'unpaired'. Stage: MAGNET field lines labelled 'external magnetic field' on cue 'external'.","tts_text":"والـ paramagnetic substance بتتشد ناحية الـ external magnetic field، بسبب الـ unpaired electrons دي.","screen_text":"Paramagnetic substance: attracts to the external magnetic field, due to the presence of unpaired electrons"},{"id":"s1l7","visual":"[CORE] FB (shot change; breaks the s1l4–s1l6 text-panel run). MISCONCEPTION te.magnetic-properties #1 (said once, small): coral tag 'A permanent magnet?' on line start + YK.wrongMark on cue 'مش'; the coral tag fades out on cue 'field' (on screen < 1.5 s in all). Switch to the right idea on cue 'field': the magnet slides out of frame and the sample hangs straight (pull 0, no arrow); label 'Attracted only inside a field' on cue 'field', held ≥ 2 s into the gap after the line, so the right label stays on screen at least as long as the wrong tag (R11).","tts_text":"بس ده مش permanent magnet: من غير field مش بيتشد خالص.","screen_text":"A permanent magnet? ✕ Attracted only inside a field"},{"id":"s1l8","visual":"[CORE] FB (shot change). SPIN model: two electrons in one box (↑↓, kit cyan/pink) on cue 'paired', circular arrows turning in opposite directions on cue 'عكس'; label 'opposite spins'.","tts_text":"طب لو كل الـ electrons paired، بـ spin عكس بعض؟","screen_text":"All electrons paired (↑↓): opposite spins"},{"id":"s1l9","visual":"[CORE] FB. The two field loops shrink to nothing on cue 'بيلغي' (grey); label 'no field' on cue 'خالص'. (Do not name 'magnetic moment' here: it is the new term of Part 2; screen keeps to 'opposite spins → no field'.) Book p.14.","tts_text":"الـ field بتاع الأول بيلغي التاني، فمفيش field خالص.","screen_text":"Opposite spins → no field"},{"id":"s1l10","visual":"[CORE] TP. NEW TERM 2 'diamagnetic' (Cairo 1000 72, white; ≥ 1 s after term 1's line) on cue 'diamagnetic'; stage: MAGNET, the zinc sample (unpaired:0, kit tag prints 'diamagnetic') swings out on cue 'بتتزق' + small coral arrow. MISCONCEPTION te.magnetic-properties #2 (said once, small): coral tag 'Not affected?' + YK.wrongMark on cue 'بتتجاهل'; the coral tag fades out on cue 'دي' (second one, < 1.5 s on screen). Switch to the right idea on cue 'بتتزق': label 'Repelled: pushed away' held ≥ 2 s into the gap after the line, so the right label stays on screen at least as long as the wrong tag (R11). Book p.14: 'repel the external magnetic field, due to pairing of all its electrons'.","tts_text":"المادة دي اسمها diamagnetic… ومش بتتجاهل الـ magnet، دي بتتزق بعيد عنه.","screen_text":"Diamagnetic: repelled (not unaffected)"},{"id":"s1l11","visual":"[CORE] FB (full-bleed). A long YK.magnet({type:'bar'}) across the bottom; 6 YK.magneticSample tubes above it (generic, untagged, tag:false, unpaired 1–5 for five, 0 for one); 5 swing in on cue 'paramagnetic', 1 swings out a little; label 'most of compounds of the transition elements are paramagnetic' (book p.13, Cairo 800 40) on cue 'compounds'.","tts_text":"والكتاب بيقول: أغلب compounds الـ transition elements بتطلع paramagnetic كده.","screen_text":"Most of compounds of the transition elements are paramagnetic"},{"id":"s1l12","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: Mn⁶⁺ (3d¹; Mn +6 and K₂MnO₄ are in the book table p.8), not in the unit's lessons or questions; one electron, so no Hund's rule is needed before its recap in Part 2, rule E2d). PREDICT model: question 'Mn⁶⁺ (3d¹): attracted or repelled?' in the text panel on line start; stage: empty 3d BOXES with tag 'Mn⁶⁺ (3d¹)' on cue 'manganese'; small MAGNET + sample (tag:false) above; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"والـ manganese six plus، الـ three d فيها electron واحد بس… هيتشد ولا يتزق؟ وقّفوا وفكّروا. <long pause>","screen_text":"Mn⁶⁺ (3d¹): attracted or repelled?","pause_after_s":3},{"id":"s1l13","visual":"[CORE] TP. One ↑ (cyan) drops into box 1 on cue 'unpaired' and box 1 highlights gold ('unpaired: 1' counter); the sample swings in (pull ≥ 0.4, visible) on cue 'paramagnetic'; answer row 'Attracted · one unpaired electron → paramagnetic' + one YK.rightMark. No Hund's rule here (one electron).","tts_text":"هيتشد: الـ electron ده unpaired، فهو paramagnetic هنا.","screen_text":"Attracted ✓ one unpaired electron → paramagnetic"},{"id":"s1l14","visual":"[CORE] MICRO-RECAP · centred YK.takeaway over the dimmed split MAGNET (in | out): ({title:'Paramagnetic and diamagnetic substances', line:'Unpaired electrons → paramagnetic (attracted) · all paired → diamagnetic (repelled)', pulse:[{word:'paramagnetic', at:YK.cue('s1l14','paramagnetic')}, {word:'diamagnetic', at:YK.cue('s1l14','diamagnetic')}]}).","tts_text":"الخلاصة: unpaired electrons يبقى paramagnetic وبيتشد، وكلها paired يبقى diamagnetic وبيتزق.","screen_text":"Unpaired electrons → paramagnetic (attracted) · all paired → diamagnetic (repelled)"},{"id":"s1l15","visual":"[CORE] SO-WHAT · FB. 3d BOXES fill 1 → 5 ↑ (each box highlights gold) on cue 'unpaired'; a YK.momentMeter({label:'pull', value:0}) with a gold '?' beside it next to the MAGNET on cue 'الشد'. Segment chip out at line end; in the pause: camera push into the PART 2 card.","tts_text":"طب كل ما الـ unpaired electrons تزيد… الشد بيزيد معاها؟","screen_text":"More unpaired electrons → a stronger pull?","pause_after_s":2.5},{"id":"s2l1","style":"curious","visual":"PART 2/7 · te.magnetic-moment-from-config · objective: Classify substances and order their magnetic moments from the d sublevel. · [CORE] Segment card in s1l15's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 2 OF 7', title:'Unpaired electrons and magnetic moment', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Unpaired electrons and magnetic moment', never cut) on line start, chip kept to the micro-recap. Line: FB YK.atom({Z:30}) with a mono '30 electrons' counter on cue 'تلاتين'; a big gold pull arrow with '?' on cue 'هيتشد'. RE-HOOK (misconception te.magnetic-properties #3).","tts_text":"الـ zinc فيه تلاتين electron… يبقى هيتشد أكتر من الكل، صح؟","screen_text":"Zn has 30 electrons. The strongest pull?"},{"id":"s2l2","visual":"[CORE] TP. NEW TERM 1 'magnetic moment' (Cairo 1000 64, gold) on cue 'magnetic'; the segment's one definition card YK.termCard({term:'Magnetic moment', def:'Increases with the number of unpaired electrons.', keys:['unpaired electrons']}) (book p.13). Stage: YK.momentMeter (label 'unpaired e^-') steps 1 → 5 as ↑ are added (gold boxes) on cue 'عدد'.","tts_text":"الكتاب بيقول: الـ magnetic moment بيزيد، كل ما عدد الـ unpaired electrons يزيد.","screen_text":"Magnetic moment increases with the number of unpaired electrons"},{"id":"s2l3","visual":"PREREQ atom.hund-rule [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · FB. Prereq YK.chip (link icon) 'Hund's rule and orbital-box diagrams'. SAME MODEL as video-short-atom.hund-rule: 5 boxes get ↑ one by one on cue 'singly', then a ↓ pairs into box 1 on cue 'pairing'. Prereq chip out at line end.","tts_text":"فاكرين الـ Hund's rule؟ الأول singly، والـ pairing بعدين.","screen_text":"Hund's rule: singly first, then pairing"},{"id":"s2l4","visual":"[CORE] TP. WORKED EXAMPLE (book p.14 exercise table, one row per line, ≤ 3 rows in the text panel). Row 1 'Zn (d^10)' on cue 'zinc'. Stage: 3d BOXES fill 5 ↑ then 5 ↓ (no highlight) on cue 'عشرة'.","tts_text":"تمرين الكتاب: الـ zinc، عشرة في الـ three d، خمس pairs مقفولة.","screen_text":"Exercise: Zn (d¹⁰): five pairs"},{"id":"s2l5","visual":"[CORE] TP. Row 1 completes: '0' (unpaired) on cue 'صفر' + 'diamagnetic' on cue 'diamagnetic'; counter 'unpaired: 0'; the s2l1 '30 electrons' tag gets a small coral ✕ on cue 'التلاتين' (MISCONCEPTION te.magnetic-properties #3 refuted: only unpaired electrons count).","tts_text":"صفر unpaired electrons… diamagnetic، رغم التلاتين electron اللي فيه.","screen_text":"Zn: 0 unpaired electrons → diamagnetic"},{"id":"s2l6","visual":"[CORE] FB (shot change; breaks the s2l4–s2l7 text-panel run): the 3d BOXES full-bleed and large (size 150) for 'Ni^2+ (d^8)' on cue 'nickel'; 5 ↑ then 3 ↓ on cue 'تمانية' (book table: [↑↓][↑↓][↑↓][↑][↑]); boxes 4–5 highlight gold on cue 'unpaired'; at line end the camera pulls back and row 2 '2 · paramagnetic' lands in the table.","tts_text":"الـ nickel two فيها تمانية: تلات pairs، واتنين unpaired فاضلين.","screen_text":"Ni²⁺ (d⁸): 2 unpaired → paramagnetic"},{"id":"s2l7","visual":"[CORE] TP. Row 3 'Fe^2+ (d^6)' on cue 'iron'; boxes: 5 ↑ then 1 ↓ on cue 'ستة'; boxes 2–5 highlight gold on cue 'unpaired'; row completes '4 · paramagnetic'.","tts_text":"والـ iron two فيها ستة: pair واحدة، وأربعة unpaired كمان.","screen_text":"Fe²⁺ (d⁶): 4 unpaired → paramagnetic"},{"id":"s2l8","visual":"[CORE] FB (shot change). Three YK.momentMeter (r 150) side by side, labels 'Zn' | 'Ni^2+' | 'Fe^2+' (book order, left → right) rise to 0 / 2 / 4 on cues 'zinc', 'nickel', 'iron'; the order row 'Zn (0) < Ni^2+ (2) < Fe^2+ (4)' (YK.formula 56) builds under them (book p.14 'write the order of the moment').","tts_text":"أقل magnetic moment للـ zinc، بعده الـ nickel two، وبعدهم الـ iron two الأعلى.","screen_text":"Magnetic moment: Zn (0) < Ni²⁺ (2) < Fe²⁺ (4)"},{"id":"s2l9","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: Ni³⁺, not in the unit's lessons or questions). PREDICT model: question 'Ni³⁺ (3d⁷): how many unpaired electrons?' in the text panel; stage: empty 3d BOXES + tag 'Ni^3+ (3d^7)' on cue 'nickel'; the three meters small (r 80) at the bottom; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"طب الـ nickel three plus، الـ three d فيها سبعة… كام unpaired؟ وقّفوا وفكّروا. <long pause>","screen_text":"Ni³⁺ (3d⁷): how many unpaired electrons?","pause_after_s":3},{"id":"s2l10","visual":"[CORE] TP. Boxes fill 5 ↑ then 2 ↓; boxes 3–5 highlight gold on cue 'تلاتة'; a fourth meter '3' (label 'Ni^3+') slides between Ni²⁺ and Fe²⁺ on cue 'بين'; answer row + one YK.rightMark.","tts_text":"تلاتة unpaired، فمكانه بين الـ nickel two والـ iron two بالظبط.","screen_text":"3 unpaired ✓ between Ni²⁺ (2) and Fe²⁺ (4)"},{"id":"s2l11","visual":"[CORE] MICRO-RECAP · centred YK.takeaway over the dimmed four meters ({title:'Unpaired electrons and magnetic moment', line:'The magnetic moment is measured by the number of unpaired electrons', pulse:[{word:'unpaired', at:YK.cue('s2l11','unpaired')}]}) (book p.14 wording).","tts_text":"الخلاصة: الـ magnetic moment بيتقاس بعدد الـ unpaired electrons، مش العدد كله.","screen_text":"Magnetic moment: measured by the number of unpaired electrons"},{"id":"s2l12","visual":"[CORE] SO-WHAT · FB. A formula card 'FeCl₃' with a '?' over the metal on cue 'compound'; the '?' becomes 'Fe^{?+}' on cue 'ion'. Segment chip out; (m1 follows).","tts_text":"بس الامتحان بيديكم compound، مش ion… نعرف الـ ion منين؟","screen_text":"But the exam gives a compound: which ion is inside?","pause_after_s":1},{"id":"m1l1","visual":"[CORE] MID-EPISODE RECAP 1 (~3:35–3:50, after Parts 1-2) · FB. YK.flow({rtl:false, layout:'row', area:{x:96,y:380,w:1728,h:320}, node:{size:40}}); header 'So far' (Cairo 800 40). Node 1 'Para / diamagnetic' (sub 'unpaired vs all paired') lit on cue 'unpaired'.","tts_text":"نلم اللي فات: كله paired يبقى diamagnetic، وفيه unpaired electrons يبقى paramagnetic وبيتشد.","screen_text":"All paired → diamagnetic · unpaired electrons → paramagnetic"},{"id":"m1l2","visual":"[CORE] FB flow: arrow + node 2 'Magnetic moment' (sub 'number of unpaired electrons') on cue 'magnetic'; nodes 1-2 glow once. In the pause: camera move into the PART 3 card.","tts_text":"والـ magnetic moment بيزيد مع عدد الـ unpaired electrons بس.","screen_text":"Magnetic moment: the number of unpaired electrons","pause_after_s":2.5},{"id":"s3l1","style":"curious","visual":"PART 3/7 · te.magnetic-moment-from-config · objective: Arrange compounds in ascending order according to their magnetic moment. · [CORE] Segment card in m1l2's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 3 OF 7', title:'Unpaired electrons and magnetic moment', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Unpaired electrons and magnetic moment', never cut) on line start, chip kept to the micro-recap. Line: TP. The three formulas (YK.formula 56) on cue 'compounds' in the book's order FeCl₃, Cr₂O₃, TiO₂ (book p.14 exercise 2). RE-HOOK.","tts_text":"تمرين الكتاب التاني: تلات compounds، نرتّبهم بالـ magnetic moment… نبدأ منين؟","screen_text":"FeCl₃, Cr₂O₃, TiO₂: ascending order of magnetic moment?"},{"id":"s3l2","visual":"PREREQ pt.oxidation-number [RECAP-PREREQ] (one line, ≤ 10 s, reference only) · TP. Prereq YK.chip (link icon) 'Oxidation state in compounds'. Rule rows build on cues 'المجموع' ('sum = 0'), 'oxygen' ('O = −2'), 'chlorine' ('Cl (chlorides) = −1'). Same model as video-short-pt.oxidation-number. Prereq chip out at line end.","tts_text":"فاكرين الـ oxidation state؟ المجموع صفر، الـ oxygen سالب اتنين، والـ chlorine سالب واحد.","screen_text":"Oxidation state: sum = 0 · O = −2 · Cl (chlorides) = −1"},{"id":"s3l3","visual":"[CORE] TP. WORKED EXAMPLE step 1 (book p.14 exercise 2). Row 'FeCl₃: 3 × (−1) = −3 → Fe = +3' builds on cues 'chlorine' and 'موجب'.","tts_text":"أول compound: الـ iron مع تلاتة chlorine… يبقى الـ iron تلاتة موجب.","screen_text":"FeCl₃: Fe = +3"},{"id":"s3l4","visual":"[CORE] FB (shot change). 4s box (pink) + 3d BOXES for Fe: the two 4s electrons leave first on cue 'four', then one 3d ↓ leaves on cue 'three'. Row 'Fe: [Ar] 4s² 3d⁶ → Fe³⁺: [Ar] 3d⁵' (YK.formula 56). Guardrail G43: no energy-order claim; the 4s leaves first as the outer level (te.ion-configuration model).","tts_text":"الـ iron بيفقد الـ four s الأول، وبعدين electron من الـ three d كمان.","screen_text":"Fe: [Ar] 4s² 3d⁶ → Fe³⁺: [Ar] 3d⁵"},{"id":"s3l5","visual":"[CORE] FB. All five ↑ turn gold on cue 'خمسة' (first); counter 'unpaired: 5' on cue 'unpaired'.","tts_text":"فاضل خمسة في الـ three d… خمسة unpaired electrons كاملين.","screen_text":"3d⁵: 5 unpaired electrons"},{"id":"s3l6","visual":"[CORE] TP. MISCONCEPTION te.magnetic-moment-from-config #1: small coral ghost row 'Fe atom 3d⁶ → 4?' + YK.wrongMark on cue 'غلط' (< 2 s); the Fe³⁺ boxes (gold, 5) re-pulse on cue 'ion'.","tts_text":"ولو عدّيتوا على الـ atom نفسه، هتطلعوا أربعة… غلط: بنعد على الـ ion نفسه.","screen_text":"Count on the atom (3d⁶ → 4)? ✕ Count on the ion"},{"id":"s3l7","visual":"[CORE] TP. Row 'Cr_2O_3: 3 × (−2) = −6 → 2 Cr share +6' builds on cues 'oxygen' and YK.cue('s3l7','chromium',1) (the first 'chromium' is in 'chromium oxide'). QUICK MID-SEGMENT CHECK (Part 3 runs 115–123 s, E1a > 120 s; needs the tts fix + pause_after_s 1): 'each Cr = ?' slot pulses on cue 'كام' with a 1 s YK.thinkRing (small, stage corner).","tts_text":"الـ chromium oxide: سالب ستة من الـ oxygen، على اتنين chromium… كل واحد كام؟","screen_text":"Cr₂O₃: 3 × (−2) = −6 shared by 2 Cr → each Cr = ?","pause_after_s":1},{"id":"s3l8","visual":"[CORE] FB. Cr boxes: 4s box (1 ↑) + 3d BOXES from the book config [Ar] 4s¹ 3d⁵ (static, labelled 'Cr: [Ar] 4s^1 3d^5'); the 4s electron leaves first, then two 3d electrons (count 5 → 3) on cue 'موجب'; 3 boxes highlight gold on cue 'unpaired'; row 'Cr^3+: 3d^3 → 3'.","tts_text":"فكل chromium تلاتة موجب، والـ three d فيها تلاتة unpaired بس.","screen_text":"Cr³⁺: 3d³ → 3 unpaired"},{"id":"s3l9","visual":"[CORE] FB. Ti boxes: 4s² and 3d² all leave on cue 'موجب'; empty 3d BOXES on cue 'فاضية'; row 'TiO₂: Ti⁴⁺ → 3d⁰ → 0'.","tts_text":"والـ titanium dioxide: أربعة موجب، والـ three d فاضية خالص.","screen_text":"TiO₂: Ti⁴⁺ → 3d⁰ (empty)"},{"id":"s3l10","visual":"[CORE] TP. MISCONCEPTION te.magnetic-moment-from-config #3: tag 'all paramagnetic?' coral + YK.wrongMark on cue 'مش' (< 2 s); the TiO₂ dish nudges out of the MAGNET (repelled) on cue 'diamagnetic'.","tts_text":"يعني مش كل compound لعنصر transition بيبقى paramagnetic… ده diamagnetic أهو.","screen_text":"Not every transition element compound is paramagnetic"},{"id":"s3l11","visual":"[CORE] FB (full-bleed). Three YK.momentMeter (labels 'TiO_2' | 'Cr_2O_3' | 'FeCl_3') rise to 0 / 3 / 5 left → right on cues 'titanium', 'chromium', 'iron'; order row 'TiO_2 < Cr_2O_3 < FeCl_3' (YK.formula 56) under them (book p.14 answer).","tts_text":"فالترتيب التصاعدي: titanium dioxide، وبعده chromium oxide، وفوقهم iron chloride بخمسة.","screen_text":"Ascending: TiO₂ (0) < Cr₂O₃ (3) < FeCl₃ (5)"},{"id":"s3l12","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: two book compounds of Mn, p.6, not in the unit's lessons or questions). FB split (first-mentioned left, E7): 'MnO_2' card on cue 'manganese' | 'KMnO_4' card on cue 'potassium'; empty 3d BOXES under each; question 'MnO₂ or KMnO₄: which has the larger magnetic moment?' across the top (Cairo 800 44); YK.thinkRing centred from cue 'وفكّروا' through the 3 s pause.","tts_text":"الـ manganese dioxide ولا الـ potassium permanganate… مين الـ magnetic moment أكبر؟ وقّفوا وفكّروا. <long pause>","screen_text":"MnO₂ or KMnO₄: which has the larger magnetic moment?","pause_after_s":3},{"id":"s3l13","visual":"[CORE] FB split left: row 'MnO_2: Mn^4+ → 3d^3' on cue 'موجب'; 3 ↑ with gold boxes on cue 'unpaired'; one YK.rightMark on the left panel.","tts_text":"الـ manganese dioxide: أربعة موجب، يعني تلاتة unpaired electrons فيه.","screen_text":"MnO₂ ✓ Mn⁴⁺: 3d³ → 3 unpaired"},{"id":"s3l14","visual":"[CORE] FB split right: row 'KMnO₄: +1 + Mn + 4 × (−2) = 0 → Mn⁷⁺ → 3d⁰' on cue 'سبعة'; boxes empty on cue 'فاضية'; tag 'diamagnetic' on cue 'diamagnetic'.","tts_text":"والـ potassium permanganate: سبعة موجب، الـ three d فاضية… diamagnetic كمان.","screen_text":"KMnO₄: Mn⁷⁺ → 3d⁰ → diamagnetic"},{"id":"s3l15","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Unpaired electrons and magnetic moment', line:'Oxidation state → 3d of the ion → count the unpaired electrons → order', pulse:[{word:'Oxidation', at:YK.cue('s3l15','oxidation')}, {word:'ion', at:YK.cue('s3l15','ion',1)} ('ion' first hits 'oxidation'), {word:'unpaired', at:YK.cue('s3l15','unpaired')}]}).","tts_text":"الخلاصة: الـ oxidation state، بعدين الـ ion، وبعدين نعد الـ unpaired electrons ونرتّب.","screen_text":"Oxidation state → the ion → count the unpaired electrons → order"},{"id":"s3l16","visual":"[CORE] SO-WHAT · FB. The gold-highlighted 3d boxes of FeCl₃ glow on cue 'electrons'; a small reaction arrow with a speed tick appears next to them on cue 'تسرّع'. Segment chip out; in the pause: camera move into the PART 4 card.","tts_text":"الـ electrons دي بتخلّي المادة تتشد… طب ممكن كمان تسرّع تفاعل؟","screen_text":"These electrons: pulled by a magnet. Can they speed up a reaction?","pause_after_s":2.5},{"id":"s4l1","style":"curious","visual":"PART 4/7 · te.catalytic-activity · objective: Explain how a catalyst changes the energy profile of a reaction. · [CORE] Segment card in s3l16's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 4 OF 7', title:'Catalytic activity of transition elements', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Catalytic activity of transition elements', never cut) on line start, chip kept to the micro-recap. Line: FB SAME MODEL as video-short-chem.catalyst (prereq of te.catalytic-activity, not recapped here): YK.beaker of H₂O₂ (label 'H_2O_2' on cue 'hydrogen'); black powder dots drop in on cue 'manganese', fast bubbles on cue 'بيفور'; a mono 'MnO_2: same mass' tag on cue 'زي'. RE-HOOK. Book fig 1-3.","tts_text":"شوية manganese dioxide على الـ hydrogen peroxide… بيفور في ثانية، وهو زي ما هو!","screen_text":"MnO₂ on H₂O₂: fast fizzing, and MnO₂ stays"},{"id":"s4l2","visual":"[CORE] TP. Headline 'Transition elements are considered as ideal catalysts' (book p.14 point 5) on cue 'transition'; 'ideal catalysts' gold on cue 'ideal'.","tts_text":"والكتاب بيقول إن الـ transition elements بتعتبر ideal catalysts فعلاً.","screen_text":"Transition elements are considered as ideal catalysts"},{"id":"s4l3","visual":"PREREQ kin.activation-energy [RECAP-PREREQ] (one line, ≤ 10 s, reference only) · FB. Prereq YK.chip (link icon) 'Activation energy and energy profile'. No short exists for kin.activation-energy: use ENERGY PROFILE model (d), single curve (no peak2): axes draw ('Potential energy', 'Progress of reaction'); the hump outlined coral on cue 'التل' with a vertical arrow labelled 'activation energy' on cue 'activation'; molecule dots try the hump, only fast ones pass on cue 'تتفاعل'. Prereq chip out at line end.","tts_text":"فاكرين الـ activation energy؟ التل اللي لازم الـ molecules تعدّيه عشان تتفاعل.","screen_text":"Activation energy: the hump the molecules must get over to react"},{"id":"s4l4","visual":"[CORE] TP. WORKED EXAMPLE (book fig 1-3, p.15). Equation row without the catalyst yet (YK.formula 56) builds on cues 'hydrogen' and 'oxygen'; stage: reactant level '2H₂O₂' and product level '2H₂O + O₂' labels on the ENERGY PROFILE.","tts_text":"مثال الكتاب: الـ hydrogen peroxide بيتحلل، ويدي oxygen ومية.","screen_text":"2H₂O₂(l) → 2H₂O(l) + O₂(g) (fig 1-3)"},{"id":"s4l5","visual":"[CORE] FB (shot change, full-bleed ENERGY PROFILE). Coral curve with label 'Activation energy without catalyst' (book fig 1-3 label) on cue 'catalyst'; 'MnO_2' appears OVER the arrow of the equation row (top band, '->[MnO2]') on cue 'manganese'; cyan dashed lower hump (peak2, draw2 0 → 1) on cue 'بيوطى'; label 'Activation energy with catalyst' on cue 'activation'. Check stills: the long kit labels must not collide at size 32–36.","tts_text":"من غير catalyst التل عالي، ومع الـ manganese dioxide بيوطى… activation energy أقل.","screen_text":"Without catalyst: high hump · with MnO₂: lower activation energy"},{"id":"s4l6","visual":"[CORE] FB. Many dots (YK.dot) ride over the cyan hump on cue 'أكتر' (custom path from energyProfile's returned px/py); tag 'speed of reaction ↑' (book wording, gold) on cue 'بيسرع'. No gauge (momentMeter is the magnetic-moment model only).","tts_text":"والتل الواطي يعني molecules أكتر بتعدّي، فالتفاعل بيسرع.","screen_text":"Lower hump → faster reaction"},{"id":"s4l7","visual":"[CORE] FB. Reactant and product levels flash on cues 'البداية', 'النهاية'; the kit dH arrow 'Net energy released' (book fig 1-3 'Net energy released by the forward reaction', shortened) shared by both humps on cue 'net'. MISCONCEPTION te.catalytic-activity #3 (after tts fix): coral tag 'Activation energy = energy released?' + YK.wrongMark on cue 'مش' (< 2 s), the Ea arrow and the dH arrow pulse in their two different colours.","tts_text":"بس البداية والنهاية ثابتين، فالـ net energy released هي هي… وهي مش الـ activation energy خالص.","screen_text":"Net energy released: the same · not the activation energy"},{"id":"s4l8","visual":"[CORE] TP. MISCONCEPTIONS te.catalytic-activity #2 and #1 (said once, small): coral tags 'more energy?' / 'more product?' + YK.wrongMark on cue 'مش' (< 2 s); then the beaker of s4l1 returns small: MnO₂ filtered out, YK.balance level (same mass; same model as video-short-chem.catalyst), tag 'used up?' + YK.wrongMark on cue 'بيخلص'.","tts_text":"فالـ catalyst مش بيزوّد الطاقة ولا الـ products… ولا بيخلص كمان.","screen_text":"More energy? ✕ More product? ✕ Used up? ✕"},{"id":"s4l9","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: two catalysts compared, made-up values; not in the unit's lessons or questions). FB split (first-mentioned left, E7): ENERGY PROFILE (labels ea:'70 kJ', no dH) on cue 'لسبعين' | the same profile with ea:'50 kJ' on cue 'لخمسين'; tag 'made-up values'; question across the top (Cairo 800 44); YK.thinkRing centred from cue 'وفكّروا' through the 3 s pause.","tts_text":"لو catalyst بيوطّي التل لسبعين kilojoule، وتاني لخمسين… مين أسرع؟ وقّفوا وفكّروا. <long pause>","screen_text":"Hump 70 kJ or 50 kJ: which catalyst gives the faster reaction? (made-up values)","pause_after_s":3},{"id":"s4l10","visual":"[CORE] FB split: dots pour over the right (50 kJ) hump on cue 'molecules'; one YK.rightMark on the right panel + 'lower activation energy → faster'.","tts_text":"اللي بخمسين: activation energy أقل، يعني molecules أكتر بتعدّي، فأسرع.","screen_text":"50 kJ ✓ lower activation energy → faster"},{"id":"s4l11","visual":"[CORE] MICRO-RECAP · centred YK.takeaway over the dimmed fig 1-3 ({title:'Catalytic activity of transition elements', line:'A catalyst lowers the activation energy; the net energy released stays the same', formula:'2H2O2_(l) ->[MnO2] 2H2O_(l) + O2_(g)', pulse:[{word:'lowers', at:YK.cue('s4l11','بيوطّي')}, {word:'same', at:YK.cue('s4l11','ثابتة')}]}).","tts_text":"الخلاصة: الـ catalyst بيوطّي الـ activation energy، والـ net energy released ثابتة.","screen_text":"A catalyst lowers the activation energy; the net energy released stays the same"},{"id":"s4l12","visual":"[CORE] SO-WHAT · FB. Camera pushes into the cyan hump until a metal SURFACE appears blurred under it on cue 'إزاي'. Segment chip out; in the pause: camera move into the PART 5 card.","tts_text":"طب الـ transition element بيوطّي التل ده إزاي أصلاً؟","screen_text":"How does a transition element lower the hump?","pause_after_s":2.5},{"id":"s5l1","style":"curious","visual":"PART 5/7 · te.catalytic-activity · objective: Explain why transition elements are used as catalysts. · [CORE] Segment card in s4l12's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 5 OF 7', title:'Catalytic activity of transition elements', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Catalytic activity of transition elements', never cut) on line start, chip kept to the micro-recap. Line: FB SURFACE in close-up, molecules drifting above it; a '?' on the surface on cue 'بيعمل'. RE-HOOK.","tts_text":"المعدن مش بيخلص ولا بيتكتب reactant… أمال بيعمل إيه بالظبط؟","screen_text":"Not used up, not a reactant. So what does the metal do?"},{"id":"s5l2","visual":"PREREQ chem.bond-breaking-energy [RECAP-PREREQ] (one line, ≤ 10 s, reference only) · FB. Prereq YK.chip (link icon) 'Bond breaking and bond forming'. No short exists for chem.bond-breaking-energy: kit YK.molecule({formula:'N2', stretch 0 → 1}) splits on cue 'بيكسر', an energy arrow into the bond on cue 'طاقة'; the coral hump of Part 4 ghosts in behind on cue 'activation'. Prereq chip out at line end.","tts_text":"فاكرين؟ التفاعل بيكسر bonds، والكسر ده محتاج طاقة… ومنها الـ activation energy أصلاً.","screen_text":"Breaking bonds needs energy → activation energy"},{"id":"s5l3","visual":"[CORE] TP. Headline '4s and 3d electrons' on cues 'four', 'three' (book p.15). Stage: SURFACE (metal 'Fe') with a pink 4s and a violet 3d YK.glowCircle on the surface atoms on cues 'four', 'three'.","tts_text":"الكتاب بيقول: السر في electrons الـ four s والـ three d بتوع المعدن.","screen_text":"4s and 3d electrons of the metal"},{"id":"s5l4","visual":"[CORE] FB (shot change, full-bleed SURFACE). WORKED CHAIN step 1 (book p.15 sentence, one step per line): N2 and H2 molecules land (m.p 0 → 1) on cue 'bonds' and the kit cyan dashed surface bonds appear; label 'surface atoms' on cue 'surface'.","tts_text":"الـ electrons دي بتعمل bonds بين الـ surface atoms والـ molecules اللي بتتفاعل.","screen_text":"① They form bonds between the surface atoms and the reacting molecules"},{"id":"s5l5","visual":"[CORE] FB SURFACE: 6–8 molecules crowd onto the surface sites on cue 'بتتلم'; label 'concentration ↑' on cue 'concentration'.","tts_text":"فالـ molecules بتتلم على الـ surface، والـ concentration بتاعتها هناك بيزيد.","screen_text":"② Concentration of the molecules on the surface increases"},{"id":"s5l6","visual":"[CORE] FB SURFACE: `stretch` 0 → 1 on every adsorbed molecule (bond thins and stretches) on cue 'بتضعف'; label 'bonds weaken' on cue 'bonds'.","tts_text":"والـ bonds جوه الـ molecules بتضعف، فكسرها أسهل.","screen_text":"③ The bonds in the reactant molecules weaken"},{"id":"s5l7","visual":"[CORE] TP. Chain rows ①→④ complete in the text panel (≤ 4 rows); stage: the cyan hump of Part 4 returns (same model) on cue 'activation'; tag 'speed of reaction ↑' on cue 'أسرع'.","tts_text":"فالـ activation energy بتقل، والتفاعل بيمشي أسرع.","screen_text":"④ Activation energy decreases → speed of reaction increases"},{"id":"s5l8","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: lump vs powder of iron; applies the surface reason; not in the unit's lessons or questions). FB split (first-mentioned left, E7): one iron cube (custom grid of grey squares) on cue 'كبيرة' | the same mass as a heap of tiny grains on cue 'powder'; question across the top; YK.thinkRing centred from cue 'وفكّروا' through the 3 s pause.","tts_text":"حتة iron كبيرة، ولا نفس الوزن powder ناعم… أنهي أسرع؟ وقّفوا وفكّروا. <long pause>","screen_text":"Iron: one big lump or a fine powder? Which works faster?","pause_after_s":3},{"id":"s5l9","visual":"[CORE] FB split: the grains' outer atoms light gold (many) vs the cube's (few) on cue 'surface'; molecules land on the grains on cue 'بتمسك'; YK.rightMark on the right panel.","tts_text":"الـ powder: فيه surface atoms أكتر بكتير، بتمسك molecules أكتر.","screen_text":"Powder ✓ more surface atoms → more molecules held"},{"id":"s5l10","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Catalytic activity of transition elements', line:'4s and 3d electrons form bonds with the reacting molecules → activation energy ↓', pulse:[{word:'4s', at:YK.cue('s5l10','four')}, {word:'3d', at:YK.cue('s5l10','three')}, {word:'bonds', at:YK.cue('s5l10','bonds')}]}) (needs the tts fix: 'bonds' spoken; until then pulse 'molecules').","tts_text":"الخلاصة: الـ four s والـ three d بيعملوا bonds مع الـ molecules، فالـ activation energy بتقل.","screen_text":"4s + 3d → bonds with the reacting molecules → activation energy ↓"},{"id":"s5l11","visual":"[CORE] SO-WHAT · FB. Three blank catalyst tags (grey) slide in over the SURFACE on cue 'catalysts'. Segment chip out.","tts_text":"طب مين الـ catalysts دي بالاسم؟ والكتاب بيستخدمها في إيه؟","screen_text":"Which metals? Which reactions?","pause_after_s":1},{"id":"m2l1","visual":"[CORE] MID-EPISODE RECAP 2 (~8:20–9:00, after Parts 3-5) · FB. YK.flow row continues the m1 chain (nodes 1-2 small, dim, on the left; explicit node x/y); header 'So far'. Node 3 'Count on the ion' (sub 'oxidation state → 3d → unpaired') on cue 'unpaired'.","tts_text":"نلم تاني: الـ unpaired electrons بنعدها على الـ ion نفسه.","screen_text":"Count the unpaired electrons on the ion"},{"id":"m2l2","visual":"[CORE] FB flow: arrow + node 4 'Catalyst' (sub 'bonds on the surface → activation energy ↓', fig 1-3 mini glyph) on cue 'catalyst'; nodes 1-4 glow once. In the pause: camera move into the PART 6 card.","tts_text":"والـ catalyst بيوطّي الـ activation energy، بالـ bonds اللي بتتعمل على الـ surface بتاعه.","screen_text":"Catalyst: bonds on the surface → activation energy ↓","pause_after_s":2.5},{"id":"s6l1","style":"curious","visual":"PART 6/7 · te.catalysis-examples · objective: Name the catalysts of the hydrogenation of oils and the Haber-Bosch method. · [CORE] Segment card in m2l2's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 6 OF 7', title:'Nickel, iron and V₂O₅ as catalysts', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Nickel, iron and V₂O₅ as catalysts', never cut) on line start, chip kept to the micro-recap. Line: FB three reaction cards with empty catalyst slots on cue 'catalyst'; slots flicker on cue 'معدنه'. RE-HOOK (misconception: swapping catalyst pairs).","tts_text":"هو فيه catalyst واحد لكل التفاعلات؟ ولا لكل تفاعل معدنه؟","screen_text":"One catalyst for every reaction?"},{"id":"s6l2","visual":"[CORE] TP. NEW TERM 1 'hydrogenation' (Cairo 1000 64) on cue 'hydrogenation'; card 1 fills 'Finely divided Ni' on cue 'nickel' (book p.14; typo 'Finally' fixed). Stage: oil drop + Ni grains.","tts_text":"أول مثال: الـ nickel، وبيبقى finely divided، في الـ hydrogenation بتاع الزيوت.","screen_text":"Finely divided nickel: hydrogenation process (of oil)"},{"id":"s6l3","visual":"[CORE] FB (shot change). YK.surface({metal:'Ni'}) with H2 molecules landing (kit has no oil molecule) on cue 'نضيف'; a generic 'oil' tag (rounded blob, label) receives the H atoms; label 'adding hydrogen' (lesson-te.catalysis-examples wording).","tts_text":"والـ hydrogenation يعني نضيف hydrogen للزيت.","screen_text":"Hydrogenation: adding hydrogen to the oil"},{"id":"s6l4","visual":"[CORE] FB. The Part 5 lump vs powder split returns small (same model) on cue 'powder'; the powder side pulses gold on cue 'توقعنا' (callback, not a new idea).","tts_text":"و finely divided يعني powder ناعم… زي ما توقعنا.","screen_text":"Finely divided = a fine powder → a huge surface"},{"id":"s6l5","visual":"PREREQ chem.ammonia-haber [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · FB. Prereq YK.chip (link icon) 'Haber-Bosch method for ammonia'. No short exists for chem.ammonia-haber: reuse the cold-open reactor (c3, E11): N2 and H2 (YK.molecule) enter, NH3 leaves, on cues 'nitrogen', 'ammonia'. Prereq chip out at line end.","tts_text":"فاكرين الـ Haber-Bosch method؟ الـ ammonia من الـ nitrogen والـ hydrogen سوا.","screen_text":"Haber-Bosch method: ammonia from nitrogen and hydrogen"},{"id":"s6l6","visual":"[CORE] FB (shot change; breaks the s6l6–s6l9 text-panel run). The c3 reactor full-bleed: grey iron granules pour in on cue 'divided'; card 2 fills 'Divided iron' on cue 'iron' (book p.14 'divided iron is used as a catalyst').","tts_text":"والـ catalyst هنا iron، وهو divided زي الـ nickel برضه.","screen_text":"Divided iron: the catalyst"},{"id":"s6l7","visual":"[CORE] TP. WORKED EXAMPLE (book p.15). Equation row builds term by term on cues 'nitrogen', 'تلاتة', 'اتنين' (YK.formula 56), ONE-WAY arrow (book), arrow empty for now.","tts_text":"الـ equation: nitrogen واحد مع تلاتة hydrogen، بيدّوا اتنين ammonia في الآخر.","screen_text":"N₂(g) + 3H₂(g) → 2NH₃(g)"},{"id":"s6l8","visual":"PREREQ chem.equation-reading [RECAP-PREREQ] (one line, ≤ 9 s, reference only; first use of 'over the arrow', before the s6l9 predict, rule E2d) · TP. Prereq YK.chip (link icon) 'Reading equations: states and conditions' on line start, out at line end. Two slot labels over the arrow: 'catalyst' on cue 'catalyst', 'conditions' on cue 'conditions'; then filled one item per cue: 'Fe' on 'iron', '500 °C' on 'وخمسمية', '200 atm' on 'atmosphere' (book p.15: 500°C / 200 atm, Fe).","tts_text":"فاكرين؟ فوق السهم بنكتب الـ catalyst والـ conditions: هنا الـ iron، وخمسمية درجة، وميتين atmosphere ضغط.","screen_text":"Over the arrow: catalyst and conditions · Fe · 500 °C · 200 atm"},{"id":"s6l9","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: the Haber-Bosch reaction with the catalyst removed; not in the unit's lessons or questions). TP: the 'Fe' over the arrow fades out on cue 'شيلنا'; question in the text panel; YK.thinkRing on the stage from cue 'وفكّروا' through the 3 s pause.","tts_text":"شيلنا الـ iron، وسيبنا الحرارة والضغط زي ما هما… الـ ammonia هتتكوّن؟ وقّفوا وفكّروا. <long pause>","screen_text":"No iron, same 500 °C and 200 atm: does ammonia still form?","pause_after_s":3},{"id":"s6l10","visual":"[CORE] FB ENERGY PROFILE (same model, labels reactants 'N_2 + 3H_2', products '2NH_3', no dH): the coral (uncatalysed) hump returns on cue 'activation'; a slow trickle of NH3 molecules on cue 'أبطأ'; one YK.rightMark + 'yes, but much slower'.","tts_text":"أيوه، بس أبطأ بكتير، عشان الـ activation energy أعلى.","screen_text":"Yes, but much slower ✓ higher activation energy"},{"id":"s6l11","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Nickel, iron and V₂O₅ as catalysts', line:'Ni: hydrogenation · Fe: Haber-Bosch (500 °C, 200 atm)', formula:'N2_(g) + 3H2_(g) ->[500 °C / 200 atm, Fe] 2NH3_(g)' (book arrow, one-way), pulse:[{word:'Ni', at:YK.cue('s6l11','nickel')}, {word:'Fe', at:YK.cue('s6l11','iron')}]}).","tts_text":"الخلاصة: الـ nickel للـ hydrogenation، والـ iron للـ Haber-Bosch بالـ conditions دي.","screen_text":"Ni: hydrogenation · Fe: Haber-Bosch (500 °C, 200 atm)"},{"id":"s6l12","visual":"[CORE] SO-WHAT · FB. Card 3 (still empty) zooms forward with a 'H₂SO₄' tag on cue 'sulphuric'. Segment chip out; in the pause: camera move into the PART 7 card.","tts_text":"طب والـ sulphuric acid؟ بيتحضّر بـ catalyst مين؟","screen_text":"And sulphuric acid? Which catalyst?","pause_after_s":2.5},{"id":"s7l1","style":"curious","visual":"PART 7/7 · te.catalysis-examples · objective: Write the contact method equations with the catalyst over the arrow. · [CORE] Segment card in s6l12's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 7 OF 7', title:'Nickel, iron and V₂O₅ as catalysts', size:100}) + objective line (Cairo 600 40, textDim, ~170 px under the title); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Nickel, iron and V₂O₅ as catalysts', never cut) on line start, chip kept to the micro-recap. Line: TP. NEW TERM 'contact method' (Cairo 1000 64) on cue 'contact'; stage: a 'V₂O₅' card (tag 'metal oxide') on cue 'vanadium'; on cue 'معدن' a small label under the card 'the oxide, not the metal V' (NO struck-through atom and NO 'not a metal' label: vanadium itself IS a transition metal, book p.5-6; R5 v4). RE-HOOK.","tts_text":"في الـ contact method، الـ catalyst مش معدن… ده الـ vanadium pentoxide بنفسه.","screen_text":"Contact method: the catalyst is V₂O₅, a metal oxide"},{"id":"s7l2","visual":"CALLBACK chem.equation-reading (≤ 5 s; the recap is s6l8, no prereq chip here) · TP. Generic YK.formula arrow with the 'catalyst' slot over it (same model as s6l8); a 'reactants' slot left of it, coral ✕ on cue 'مش'. Refutes te.catalysis-examples misconception #2 (catalyst written as a reactant).","tts_text":"وزي ما قلنا: اللي فوق السهم مش من الـ reactants.","screen_text":"Over the arrow: the catalyst, not a reactant"},{"id":"s7l3","visual":"[CORE] FB (shot change). Card 3 fills 'Contact method → sulphuric acid' on cue 'contact' (book p.15).","tts_text":"والـ contact method ده لتحضير الـ sulphuric acid بالظبط.","screen_text":"Contact method: preparation of sulphuric acid"},{"id":"s7l4","visual":"[CORE] TP. WORKED EXAMPLE (book p.15 figure). Equation row 1 builds on cues 'sulphur' (first), 'oxygen', 'trioxide' (YK.formula 56), one-way arrow empty for now.","tts_text":"الخطوة الأولى: اتنين sulphur dioxide مع oxygen، بيدّوا اتنين sulphur trioxide هنا.","screen_text":"2SO₂(g) + O₂(g) → 2SO₃(g)"},{"id":"s7l5","visual":"[CORE] TP. Over arrow 1: 'V₂O₅' on cue 'vanadium', '450 °C' on cue 'وأربعمية' (book: V2O5/450°C).","tts_text":"وفوق السهم: الـ vanadium pentoxide، وأربعمية وخمسين درجة.","screen_text":"Over the arrow: V₂O₅ · 450 °C"},{"id":"s7l6","visual":"[CORE] TP. Equation row 2 'SO3_(s) + H2O_(l) -> H2SO4_(aq)' (book p.15 states) builds on cues 'trioxide', 'sulphuric'; no catalyst over this arrow (book).","tts_text":"وبعدين الـ sulphur trioxide مع المية، بيدّوا الـ sulphuric acid نفسه.","screen_text":"SO₃(s) + H₂O(l) → H₂SO₄(aq)"},{"id":"s7l7","visual":"[CORE] FB (full-bleed). The four book pairs as cards left → right in book order: Ni | Fe | V₂O₅ | MnO₂, the MnO₂ card fills on cue 'manganese' with 'decomposition of H₂O₂' on cue 'decomposition'.","tts_text":"ومعاهم الـ manganese dioxide، اللي بيعمل decomposition للـ hydrogen peroxide من الأول.","screen_text":"MnO₂: decomposition of H₂O₂ (fig 1-3)"},{"id":"s7l8","visual":"[CORE] FB. MISCONCEPTION te.catalysis-examples #1: links 'Fe → ammonia' on cue 'iron', 'V₂O₅ → sulphuric acid' on cue 'vanadium'; then the Fe and V₂O₅ cards try to swap places (coral, < 2 s), get a YK.wrongMark and snap back on cue 'العكس'.","tts_text":"أوعوا تبدّلوهم: الـ iron للـ ammonia، والـ vanadium pentoxide للـ sulphuric acid، مش العكس.","screen_text":"Swapped pairs? ✕ Fe → ammonia · V₂O₅ → sulphuric acid"},{"id":"s7l9","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: Fischer-Tropsch, book p.7 'conversion of water gas (mixture of hydrogen and carbon monoxide) to a fuel', met in the te-uses episode; not in this unit's lessons or questions). TP: row 'water gas (H_2 + CO) -> fuel' (YK.formula 48) with an 'Fe' card hovering between the reactant side and the arrow on cue 'iron'; after the tts fix the card pulses 'unchanged' on cue 'سليم'; question in the text panel; YK.thinkRing on the stage from cue 'وفكّروا' through the 3 s pause.","tts_text":"في الـ Fischer-Tropsch method الـ iron بيطلع سليم… reactant ولا فوق السهم؟ وقّفوا وفكّروا.","screen_text":"Fe in the Fischer-Tropsch method: a reactant, or over the arrow?","pause_after_s":3.45},{"id":"s7l10","visual":"[CORE] TP. The Fe card moves over the arrow ('->[Fe]') on cue 'فوق'; answer slot + one YK.rightMark on cue 'catalyst'; 'not used up' tag on cue 'بيخلص'.","tts_text":"فوق السهم: هو catalyst، بيسرّع ومش بيخلص.","screen_text":"Over the arrow ✓ a catalyst: not used up"},{"id":"s7l11","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Nickel, iron and V₂O₅ as catalysts', line:'V₂O₅: contact method, 450 °C, over the arrow', formula:'2SO2_(g) + O2_(g) ->[V2O5 / 450 °C] 2SO3_(g)', pulse:[{word:'V₂O₅', at:YK.cue('s7l11','vanadium')}, {word:'contact', at:YK.cue('s7l11','contact')}]}).","tts_text":"الخلاصة: الـ vanadium pentoxide للـ contact method، بأربعمية وخمسين درجة فوق السهم.","screen_text":"V₂O₅: contact method, 450 °C, over the arrow"},{"id":"s7l12","visual":"[CORE] SO-WHAT · FB. Camera pulls out from the four cards to an empty flow row. Segment chip out.","tts_text":"يلا نلم الحلقة كلها في سلسلة واحدة.","screen_text":"The whole episode in one chain","pause_after_s":1},{"id":"z1","visual":"[CORE] CLOSING SUMMARY · FB. YK.flow({rtl:false}) in book order, two rows with EXPLICIT node x/y and custom arcs (6 nodes do not fit one row at ≥ 32 px): row A magnetism y 330 (Paramagnetic · Diamagnetic · Magnetic moment · Count on the ion), row B catalysis y 700 (Catalytic activity · Examples). Node 1 'Paramagnetic' (sub 'unpaired electrons') on cue 'unpaired', arrow + node 2 'Diamagnetic' (sub 'all paired') on cue 'diamagnetic'.","tts_text":"فيه unpaired electrons يبقى paramagnetic، وكلها paired يبقى diamagnetic وبتتزق.","screen_text":"Unpaired electrons → paramagnetic · all paired → diamagnetic"},{"id":"z2","visual":"[CORE] FB flow: arrow + node 3 'Magnetic moment' (sub 'number of unpaired electrons') on cue 'magnetic'.","tts_text":"والـ magnetic moment بيزيد مع عدد الـ unpaired electrons بس.","screen_text":"Magnetic moment: the number of unpaired electrons"},{"id":"z3","visual":"[CORE] FB flow: arrow + node 4 'Count on the ion' on cue 'oxidation'.","tts_text":"ومن الـ compound: الـ oxidation state، بعدين الـ ion، ونعد الـ unpaired electrons اللي فيه.","screen_text":"Compound → oxidation state → ion → count unpaired electrons"},{"id":"z4","visual":"[CORE] FB flow: arrow (row A → row B) + node 5 'Catalytic activity' (sub '4s + 3d: bonds with the molecules → activation energy ↓', mini fig 1-3 glyph: two humps) on cue 'four'. (Node 4 'Count on the ion' comes from the [NEW LINE after z2].)","tts_text":"والـ four s والـ three d بيعملوا bonds مع الـ molecules، فالـ activation energy بتقل.","screen_text":"4s + 3d → bonds with the molecules → activation energy ↓"},{"id":"z5","visual":"[CORE] FB flow: arrow + node 6 'Examples' with chips 'Ni: hydrogenation' on cue 'nickel', 'Fe: Haber-Bosch' on cue 'iron'.","tts_text":"الـ nickel للـ hydrogenation، والـ iron للـ Haber-Bosch، دول أول مثالين.","screen_text":"Ni: hydrogenation · Fe: Haber-Bosch"},{"id":"z6","visual":"[CORE] FB flow: node 6 gains chip 'V₂O₅: contact method' on cue 'vanadium'; all six nodes glow once.","tts_text":"والـ vanadium pentoxide للـ contact method في الآخر.","screen_text":"V₂O₅: contact method"},{"id":"z7","visual":"[CORE] BIG QUESTION ANSWERED (1/2) · FB: the cold-open MAGNET with the iron sample pulled in + 3d boxes with gold highlights beside it; the gold tag 'Why pulled in?' gets ✓ on cue 'unpaired'.","tts_text":"فإجابة سؤالنا: بتتشد للـ magnet عشان الـ unpaired electrons اللي فيها.","screen_text":"Why pulled in? Unpaired electrons ✓"},{"id":"z8","visual":"[CORE] BIG QUESTION ANSWERED (2/2) · FB: the cold-open reactor granules + SURFACE + cyan lower hump; the tag 'Why ideal catalysts?' ✓ on cue 'activation'.","tts_text":"وهي ideal catalysts: الـ four s والـ three d بيقللوا الـ activation energy هنا.","screen_text":"Why ideal catalysts? 4s and 3d → activation energy ↓ ✓"},{"id":"z9","visual":"[CORE] RECALL 1/3 (Parts 1-3; NEW case: manganese(II) sulphate, book p.6 compound, not in the unit's lessons or questions; book 'give reasons' form) · TP. Question in the text panel; stage: empty 3d BOXES with tag 'MnSO_4'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"سؤال: ليه الـ manganese sulphate مادة paramagnetic؟ وقّفوا وفكّروا. <long pause>","screen_text":"Give reasons: MnSO₄ is a paramagnetic substance.","pause_after_s":3},{"id":"z10","visual":"[CORE] FB (breaks the text-panel run): boxes fill 5 ↑, all highlight gold, on cue 'خمسة' (first); MAGNET swings the sample in on cue 'فبتتشد'; answer row 'Mn^2+: 3d^5 → 5 unpaired electrons' + one YK.rightMark.","tts_text":"الـ manganese اتنين موجب: خمسة unpaired electrons في الـ three d… فبتتشد.","screen_text":"Mn²⁺: 3d⁵ → 5 unpaired electrons ✓"},{"id":"z11","visual":"[CORE] RECALL 2/3 (Parts 4-5, book Evaluation Q7.11 p.27 form) · TP. 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شوية من compound فيه iron جنب magnet\nقوي بيتشد ناحيته\nوحطّوا compound فيه zinc بيتزق بعيد حاجة\nصغيرة خالص\nوفي مصنع الـ ammonia شوية iron بيسرّعوا\nالتفاعل ومش بيخلصوا\nطب ليه بيتشدوا للـ magnet وليه هما ideal\ncatalysts بالشكل ده\nالحلقة دي عن الـ magnetic properties والـ\ncatalytic activity بتاعتهم\nنفس الـ magnet حاجة بتتشد وحاجة بتتزق ليه\nفاكرين الـ magnetic field الـ region\nحوالين الـ magnet اللي قوته بتأثر فيها\nوالـ electron بالـ spin بتاعه بيعمل\nmagnetic field صغير\nلو الـ electron ده unpaired الـ field\nبتاعه بيفضل موجود\nوالمادة اللي فيها unpaired electrons كده\nاسمها paramagnetic في الكتاب\nوالـ paramagnetic substance بتتشد ناحية\nالـ external magnetic field بسبب الـ\nunpaired electrons دي\nبس ده مش permanent magnet من غير field مش\nبيتشد خالص\nطب لو كل الـ electrons paired بـ spin عكس\nبعض\nالـ field بتاع الأول بيلغي التاني فمفيش\nfield خالص\nالمادة دي اسمها diamagnetic ومش بتتجاهل\nالـ magnet دي بتتزق بعيد عنه\nوالكتاب بيقول أغلب compounds الـ\ntransition elements بتطلع paramagnetic كده\nوالـ manganese six plus الـ three d فيها\nelectron واحد بس هيتشد ولا يتزق وقّفوا\nوفكّروا\nهيتشد الـ electron ده unpaired فهو\nparamagnetic هنا\nالخلاصة unpaired electrons يبقى\nparamagnetic وبيتشد وكلها paired يبقى\ndiamagnetic وبيتزق\nطب كل ما الـ unpaired electrons تزيد الشد\nبيزيد معاها\nالـ zinc فيه تلاتين electron يبقى هيتشد\nأكتر من الكل صح\nالكتاب بيقول الـ magnetic moment بيزيد كل\nما عدد الـ unpaired electrons يزيد\nفاكرين الـ Hund's rule الأول singly والـ\npairing بعدين\nتمرين الكتاب الـ zinc عشرة في الـ three d\nخمس pairs مقفولة\nصفر unpaired electrons diamagnetic رغم\nالتلاتين electron اللي فيه\nالـ nickel two فيها تمانية تلات pairs\nواتنين unpaired فاضلين\nوالـ iron two فيها ستة pair واحدة وأربعة\nunpaired كمان\nأقل magnetic moment للـ zinc بعده الـ\nnickel two وبعدهم الـ iron two الأعلى\nطب الـ nickel three plus الـ three d فيها\nسبعة كام unpaired وقّفوا وفكّروا\nتلاتة unpaired فمكانه بين الـ nickel two\nوالـ iron two بالظبط\nالخلاصة الـ magnetic moment بيتقاس بعدد\nالـ unpaired electrons مش العدد كله\nبس الامتحان بيديكم compound مش ion نعرف\nالـ ion منين\nنلم اللي فات كله paired يبقى diamagnetic\nوفيه unpaired electrons يبقى paramagnetic\nوبيتشد\nوالـ magnetic moment بيزيد مع عدد الـ\nunpaired electrons بس\nتمرين الكتاب التاني تلات compounds نرتّبهم\nبالـ magnetic moment نبدأ منين\nفاكرين الـ oxidation state المجموع صفر الـ\noxygen سالب اتنين والـ chlorine سالب واحد\nأول compound الـ iron مع تلاتة chlorine\nيبقى الـ iron تلاتة موجب\nالـ iron بيفقد الـ four s الأول وبعدين\nelectron من الـ three d كمان\nفاضل خمسة في الـ three d خمسة unpaired\nelectrons كاملين\nولو عدّيتوا على الـ atom نفسه هتطلعوا\nأربعة غلط بنعد على الـ ion نفسه\nالـ chromium oxide سالب ستة من الـ oxygen\nعلى اتنين chromium كل واحد كام\nفكل chromium تلاتة موجب والـ three d فيها\nتلاتة unpaired بس\nوالـ titanium dioxide أربعة موجب والـ\nthree d فاضية خالص\nيعني مش كل compound لعنصر transition بيبقى\nparamagnetic ده diamagnetic أهو\nفالترتيب التصاعدي titanium dioxide وبعده\nchromium oxide وفوقهم iron chloride بخمسة\nالـ manganese dioxide ولا الـ potassium\npermanganate مين الـ magnetic moment أكبر\nوقّفوا وفكّروا\nالـ manganese dioxide أربعة موجب يعني\nتلاتة unpaired electrons فيه\nوالـ potassium permanganate سبعة موجب الـ\nthree d فاضية diamagnetic كمان\nالخلاصة الـ oxidation state بعدين الـ ion\nوبعدين نعد الـ unpaired electrons ونرتّب\nالـ electrons دي بتخلّي المادة تتشد طب\nممكن كمان تسرّع تفاعل\nشوية manganese dioxide على الـ hydrogen\nperoxide بيفور في ثانية وهو زي ما هو\nوالكتاب بيقول إن الـ transition elements\nبتعتبر ideal catalysts فعلا\nفاكرين الـ activation energy التل اللي\nلازم الـ molecules تعدّيه عشان تتفاعل\nمثال الكتاب الـ hydrogen peroxide بيتحلل\nويدي oxygen ومية\nمن غير catalyst التل عالي ومع الـ\nmanganese dioxide بيوطى activation energy\nأقل\nوالتل الواطي يعني molecules أكتر بتعدّي\nفالتفاعل بيسرع\nبس البداية والنهاية ثابتين فالـ net energy\nreleased هي هي وهي مش الـ activation\nenergy خالص\nفالـ catalyst مش بيزوّد الطاقة ولا الـ\nproducts ولا بيخلص كمان\nلو catalyst بيوطّي التل لسبعين kilojoule\nوتاني لخمسين مين أسرع وقّفوا وفكّروا\nاللي بخمسين activation energy أقل يعني\nmolecules أكتر بتعدّي فأسرع\nالخلاصة الـ catalyst بيوطّي الـ activation\nenergy والـ net energy released ثابتة\nطب الـ transition element بيوطّي التل ده\nإزاي أصلا\nالمعدن مش بيخلص ولا بيتكتب reactant أمال\nبيعمل إيه بالظبط\nفاكرين التفاعل بيكسر bonds والكسر ده محتاج\nطاقة ومنها الـ activation energy أصلا\nالكتاب بيقول السر في electrons الـ four s\nوالـ three d بتوع المعدن\nالـ electrons دي بتعمل bonds بين الـ\nsurface atoms والـ molecules اللي بتتفاعل\nفالـ molecules بتتلم على الـ surface والـ\nconcentration بتاعتها هناك بيزيد\nوالـ bonds جوه الـ molecules بتضعف فكسرها\nأسهل\nفالـ activation energy بتقل والتفاعل بيمشي\nأسرع\nحتة iron كبيرة ولا نفس الوزن powder ناعم\nأنهي أسرع وقّفوا وفكّروا\nالـ powder فيه surface atoms أكتر بكتير\nبتمسك molecules أكتر\nالخلاصة الـ four s والـ three d بيعملوا\nbonds مع الـ molecules فالـ activation\nenergy بتقل\nطب مين الـ catalysts دي بالاسم والكتاب\nبيستخدمها في إيه\nنلم تاني الـ unpaired electrons بنعدها على\nالـ ion نفسه\nوالـ catalyst بيوطّي الـ activation energy\nبالـ bonds اللي بتتعمل على الـ surface\nبتاعه\nهو فيه catalyst واحد لكل التفاعلات ولا لكل\nتفاعل معدنه\nأول مثال الـ nickel وبيبقى finely divided\nفي الـ hydrogenation بتاع الزيوت\nوالـ hydrogenation يعني نضيف hydrogen\nللزيت\nو finely divided يعني powder ناعم زي ما\nتوقعنا\nفاكرين الـ Haber-Bosch method الـ ammonia\nمن الـ nitrogen والـ hydrogen سوا\nوالـ catalyst هنا iron وهو divided زي الـ\nnickel برضه\nالـ equation nitrogen واحد مع تلاتة\nhydrogen بيدّوا اتنين ammonia في الآخر\nفاكرين فوق السهم بنكتب الـ catalyst والـ\nconditions هنا الـ iron وخمسمية درجة\nوميتين atmosphere ضغط\nشيلنا الـ iron وسيبنا الحرارة والضغط زي ما\nهما الـ ammonia هتتكوّن وقّفوا وفكّروا\nأيوه بس أبطأ بكتير عشان الـ activation\nenergy أعلى\nالخلاصة الـ nickel للـ hydrogenation والـ\niron للـ Haber-Bosch بالـ conditions دي\nطب والـ sulphuric acid بيتحضّر بـ catalyst\nمين\nفي الـ contact method الـ catalyst مش معدن\nده الـ vanadium pentoxide بنفسه\nوزي ما قلنا اللي فوق السهم مش من الـ\nreactants\nوالـ contact method ده لتحضير الـ\nsulphuric acid بالظبط\nالخطوة الأولى اتنين sulphur dioxide مع\noxygen بيدّوا اتنين sulphur trioxide هنا\nوفوق السهم الـ vanadium pentoxide وأربعمية\nوخمسين درجة\nوبعدين الـ sulphur trioxide مع المية\nبيدّوا الـ sulphuric acid نفسه\nومعاهم الـ manganese dioxide اللي بيعمل\ndecomposition للـ hydrogen peroxide من\nالأول\nأوعوا تبدّلوهم الـ iron للـ ammonia والـ\nvanadium pentoxide للـ sulphuric acid مش\nالعكس\nفي الـ Fischer-Tropsch method الـ iron\nبيطلع سليم reactant ولا فوق السهم وقّفوا\nوفكّروا\nفوق السهم هو catalyst بيسرّع ومش بيخلص\nالخلاصة الـ vanadium pentoxide للـ contact\nmethod بأربعمية وخمسين درجة فوق السهم\nيلا نلم الحلقة كلها في سلسلة واحدة\nفيه unpaired electrons يبقى paramagnetic\nوكلها paired يبقى diamagnetic وبتتزق\nوالـ magnetic moment بيزيد مع عدد الـ\nunpaired electrons بس\nومن الـ compound الـ oxidation state بعدين\nالـ ion ونعد الـ unpaired electrons اللي\nفيه\nوالـ four s والـ three d بيعملوا bonds مع\nالـ molecules فالـ activation energy بتقل\nالـ nickel للـ hydrogenation والـ iron للـ\nHaber-Bosch دول أول مثالين\nوالـ vanadium pentoxide للـ contact method\nفي الآخر\nفإجابة سؤالنا بتتشد للـ magnet عشان الـ\nunpaired electrons اللي فيها\nوهي ideal catalysts الـ four s والـ three\nd بيقللوا الـ activation energy هنا\nسؤال ليه الـ manganese sulphate مادة\nparamagnetic وقّفوا وفكّروا\nالـ manganese اتنين موجب خمسة unpaired\nelectrons في الـ three d فبتتشد\nتاني سؤال ليه الـ transition elements\nبتعتبر ideal catalysts وقّفوا وفكّروا\nعشان الـ four s والـ three d بيعملوا bonds\nمع الـ molecules اللي بتتفاعل\nآخر سؤال الـ catalyst بتاع الـ\nhydrogenation وبتاع الـ contact method\nوقّفوا وفكّروا\nالأول الـ nickel وبيبقى finely divided\nوالتاني الـ vanadium pentoxide بتاعنا\nالحلقة الجاية الـ iron ores والـ\nextraction بتاع الـ iron منها","countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"series_id":"chem-s3-en.ch1#sessions","episode_no":5,"episode_count":9,"lessons":["chem-s3-en.lesson-chem.ammonia-haber","chem-s3-en.lesson-chem.catalyst","chem-s3-en.lesson-chem.equation-reading","chem-s3-en.lesson-kin.activation-energy","chem-s3-en.lesson-te.catalysis-examples","chem-s3-en.lesson-te.catalytic-activity","chem-s3-en.lesson-te.magnetic-moment-from-config","chem-s3-en.lesson-te.magnetic-properties"]},{"id":"chem-s3-en.video-episode-fe-extraction","kind":"episode","version":4,"ord":364,"content_lang":"ar-EG","primary_concept_id":"fe.occurrence","concepts":[{"concept_id":"fe.occurrence","role":"primary"},{"concept_id":"fe.blast-furnace-reduction","role":"secondary"},{"concept_id":"fe.midrex-reduction","role":"secondary"},{"concept_id":"fe.ore-dressing","role":"secondary"},{"concept_id":"fe.ores","role":"secondary"},{"concept_id":"fe.roasting","role":"secondary"},{"concept_id":"fe.steel-production","role":"secondary"}],"title":"Iron ores and extraction of iron","payload":{"title":"Iron ores and extraction of iron","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"16:9","format":"episode","script":[{"id":"c1","visual":"[CORE] COLD OPEN · FB. EPISODE MODELS (kit lib/industry.js, reuse in every part, E11): (a) ORE = YK.ore rocks in the book colours (hematite blood red, limonite yellow, magnetite black + magnetic rim, siderite yellowish grey; YK.ores data = book table p.16), %Fe gauge (o.gauge) only when a % is spoken. (b) STAGE TRACK = a thin LTR strip at the bottom of the stage with the book's three stages 'Ore dressing → Reduction of iron ores → Iron production' (p.17-18); the current stage lit gold; shown at each part card. (c) MACHINES = YK.crusher, YK.sinter, YK.magSeparator (ore dressing), YK.kiln (roasting; gases only those spoken), YK.furnace type 'blast' / 'midrex' (labels only the book's: CO, CO + H₂, Fe, '> 700 °C'; NO zones, NO slag, NO limestone, G46). (d) EQUATION rows = YK.formula 56 with state symbols and the book's condition over a one-way arrow (Δ, 'higher than 700 °C'). (e) OXYGEN TOKENS = red O discs on an Fe₂O₃ token; each CO / H₂ token lifts one O (reduction model, same as video-short-redox.basic's oxygen hand-over). (g) ORE TABLE (Part 2, E2c v6) = ONE table in the text panel that builds one row per ore line, columns 'Ore' | 'Formula' | 'Fe %' (Cairo 800 36 / formulas JetBrains Mono 40, header Cairo 800 32 textDim, row h 84, table x 96–740, y 300–720), colour swatch dot (the ore's book colour) before each ore name; the chemical name, colour word and place go on the stage under the rock; the table stays for the whole part and returns small in m1l2. (h) PAGE: load lib/industry.js AND lib/short.js (YK.thinkRing; template.html does not load it). YK.furnace always with highlight:null (no zone outlines, G46). (f) PIE % = a mass bar split 'iron' (steel grey) vs 'rest' (dim), for every iron-% statement. Shot: a steel bridge silhouette full-bleed (frame 0 already on screen at 40%, drift ≤ 2%); label 'metal' on cue 'metal', 'heavy industries' on cue 'heavy' (book p.16 first line); on cue 'بيطلع' the camera tilts down from the bridge into the ground (shot change): a dark rock face, a red-brown ORE rock (unlabelled, no name yet) breaks loose on cue 'صخر'; second screen line 'It comes out of the ground as rock'.","tts_text":"الحديد أهم metal في الـ heavy industries… بس بيطلع من الأرض صخر.","screen_text":"Iron: the most important metal in heavy industries · it comes out of the ground as rock"},{"id":"c2","visual":"[CORE] FB split (E7, first-mentioned left, identical scale), cut in on line start: left YK.furnace({type:'blast', labels:false}) small with tag 'Helwan' on cue 'blast'; right YK.furnace({type:'midrex', labels:false}) with tag 'Dekheila' on cue 'Midrex'. Simple Egypt outline with two dots (Cairo/Helwan, Alexandria/Dekheila). Local hook only (research-visualization: Helwan Iron & Steel, blast furnace, liquidated 2021; Ezz Dekheila Midrex): past tense, no dates or capacities on screen.","tts_text":"ومصر عملت حديد بطريقتين: الـ blast furnace في حلوان، والـ Midrex furnace في الدخيلة.","screen_text":"Egypt: a blast furnace (Helwan) · a Midrex furnace (Dekheila)"},{"id":"c3","style":"curious","visual":"[CORE] BIG QUESTION · FB. Previous shots dim to 30%; card centred (Cairo 1000 84) 'How does a rock become steel?' on line start, 'steel' gold on cue 'steel'; held through the pause, then shrinks to a gold tag top-right (returns in z7).","tts_text":"طب إزاي حتة صخر بتبقى steel في الآخر؟","screen_text":"How does a rock become steel?","pause_after_s":1},{"id":"t1","visual":"[CORE] TITLE CARD (≤ 4 s from line start). YK.titleCard({title:'Iron ores and extraction of iron', chip:'Unit 6', subtitle:'Chapter 1: Transition Elements'}) Cairo 1000 ≤ 120; parts row under it (2 columns, YK.para Cairo 800 32, maxWidth 800): 1 Iron: abundance and suitability of iron ore · 2 Important iron ores · 3 Ore dressing: crushing, sintering, concentrating · 4 Roasting of iron ore: drying the ore · 5 Roasting of iron ore: iron % and impurities · 6 Reduction in the blast furnace · 7 Reduction in the Midrex furnace · 8 Iron production and steel. Then camera move (1.2 s, no fade) onto item 1, which grows into the PART 1 card.","tts_text":"الحلقة دي عن الـ iron ores، والـ extraction بتاع الحديد منها.","screen_text":"Iron ores and extraction of iron","pause_after_s":2.5},{"id":"s1l1","style":"curious","visual":"PART 1/8 · fe.occurrence · objective: State where iron is found and what makes an ore suitable. · [CORE] Segment card in t1's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 1 OF 8', title:'Iron: abundance and suitability of iron ore', size:100}) + objective line (Cairo 600 40, textDim); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron: abundance and suitability of iron ore', never cut) on line start, chip kept to the micro-recap. Line: FB Earth cutaway (thin crust ring, core disc; same model as lesson-fe.occurrence's diagram) on line start; 'crust' label on cue 'crust'; a 'Fe ?' tag hovers over the crust. RE-HOOK.","tts_text":"بس هل الحديد أكتر عنصر في الـ crust بتاعة الأرض؟","screen_text":"Iron: first in Earth's crust?"},{"id":"s1l2","visual":"[CORE] TP + rank tiles (stage). Four EQUAL-size rank tiles build left → right, no bar heights and no % (the book gives only the order): '1st O' on cue 'oxygen', '2nd Si' on cue 'silicon', '3rd Al' on cue 'aluminum', then '4th Fe' (gold) on cue 'وبعدهم'. Refutes fe.occurrence misconception #1 (iron is the most abundant). Book p.16.","tts_text":"لأ… قبله الـ oxygen، والـ silicon، والـ aluminum، وبعدهم الحديد.","screen_text":"4th: after oxygen, silicon and aluminum"},{"id":"s1l3","visual":"[CORE] FB Earth cutaway again: PIE % chip '5% by mass' on the crust on cue 'خمسة'; a gold gradient arrow from crust to core on cue 'core' (lesson diagram model). Book p.16.","tts_text":"خمسة في المية من كتلة الـ crust، وبيزيد كل ما نقرب للـ core جوه.","screen_text":"5% of the crust by mass · more toward the core"},{"id":"s1l4","visual":"[CORE] FB (shot change): a meteorite streaks in from top-right on cue 'meteorites' and lands as a shiny grey lump; tag 'pure iron (90%)' on cue 'تسعين'. Refutes misconception #2 (iron is mined as pure metal). NEW TERM 1/3 'meteorites'.","tts_text":"الحديد النقي، تسعين في المية، بس في الـ meteorites من الفضا.","screen_text":"Pure iron (90%): only in meteorites"},{"id":"s1l5","visual":"PREREQ chem.elements-compounds-mixtures [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Elements, compounds and mixtures' under the segment chip. No short is published yet for this prerequisite: particle model drawn with YK.atomDisc (NOT YK.particles, which is ambient decoration): left box of joined two-colour disc pairs labelled 'compound' on cue 'compound'; right box of loose, unjoined particles of two kinds labelled 'mixture' on cue 'mixture'. Prereq chip out at line end.","tts_text":"فاكرين؟ الـ compound فيه elements متحدة، والـ mixture حاجات متخلطة بس.","screen_text":"Compound: elements combined · Mixture: just mixed"},{"id":"s1l6","visual":"[CORE] FB zoom-through into a red-brown ORE rock: clusters (compound model) tagged 'iron compounds' on cue 'compounds', sub-tag 'mostly oxides' on cue 'oxides' (not 'iron oxides': siderite FeCO₃ is a carbonate, book p.16 table); loose sand-coloured grains between them tagged 'impurities' on cue 'impurities'; a 'mixture' bracket over both. Title 'Iron ore' on cue 'فيه'. NEW TERM 2/3 'iron ore'. Book p.16.","tts_text":"وفي الـ crust بيبقى ore: فيه iron compounds، أغلبها oxides، متخلطة مع impurities كتير.","screen_text":"Iron ore: iron compounds (mostly oxides) mixed with impurities"},{"id":"s1l7","visual":"[CORE] TP list (≤ 3 items) builds: header 'Suitability of iron ore' on cue 'suitability' (NEW TERM 3/3); item '1. iron percentage' on cue 'نسبة' with a PIE % bar beside the rock on the stage.","tts_text":"والـ suitability بتاعة الـ ore بتعتمد على نسبة الـ iron فيه.","screen_text":"Suitability of iron ore: 1. iron percentage"},{"id":"s1l8","visual":"[CORE] TP item '2. composition of the impurities' on cue 'impurities' (the sand grains in the rock pulse); item '3. harmful elements' on cue 'harmful'; three coral chips 'S', 'P', 'As' pop on the rock on cues 'sulphur', 'phosphorus', 'arsenic'. Book p.16.","tts_text":"وعلى الـ impurities، والـ harmful elements زي الـ sulphur والـ phosphorus والـ arsenic كمان.","screen_text":"2. composition of the impurities · 3. harmful elements: S, P, As"},{"id":"s1l9","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: a made-up ore, high iron % but arsenic; not in the unit's lessons or questions). Question in the text panel; stage: rock A '55% Fe' on line start + coral 'As' chip on cue 'معاه'; rock B '50% Fe' (no chips) beside it; tag 'made-up values'; YK.thinkRing on the stage from cue 'وفكّروا' through the 3 s pause.","tts_text":"طب ore فيه iron أكتر، بس معاه arsenic… أكيد suitable؟ وقّفوا وفكّروا.","screen_text":"More iron, but with arsenic: surely more suitable?","pause_after_s":3.3},{"id":"s1l10","visual":"[CORE] FB split (E7, first-mentioned left, identical scale; breaks the text-panel run s1l7–s1l9): left rock A '55% Fe' with the coral 'As' chip, right rock B '50% Fe'; headline 'Not surely' + YK.wrongMark on 'surely' at line start (top of frame, Cairo 1000 64); on cue 'harmful' rock A's 'As' chip pulses and a small tag 'harmful element' appears under it; on cue 'iron' both % tags pulse ('not only the iron %'). NO ✓ on rock B (the book gives no rule to rank them). Refutes misconception #3 (only the iron % decides).","tts_text":"مش أكيد: الـ harmful elements بتفرق، مش نسبة الـ iron بس.","screen_text":"Not surely ✗ harmful elements count too, not only the iron %"},{"id":"s1l11","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron: abundance and suitability of iron ore', line:'4th in Earth\\'s crust · suitability: three factors', pulse:[{word:'4th', at:YK.cue('s1l11','رابع')}, {word:'suitability', at:YK.cue('s1l11','suitability')}]}).","tts_text":"الخلاصة: رابع عنصر في الـ crust، والـ suitability ليها تلات عوامل.","screen_text":"4th in Earth's crust · suitability: three factors"},{"id":"s1l12","visual":"[CORE] SO-WHAT · FB. Four dim ORE silhouettes (grey, no names) slide in on cue 'compounds'. Segment chip out; in the pause: camera move into the PART 2 card.","tts_text":"طب إيه الـ iron compounds اللي في الـ ores دي؟","screen_text":"Which iron compounds are in these ores?","pause_after_s":2.5},{"id":"s2l1","visual":"PART 2/8 · fe.ores · objective: Identify the four iron ores by formula, colour and iron %. · [CORE] Segment card in s1l12's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 2 OF 8', title:'Important iron ores', size:100}) + objective line (Cairo 600 40, textDim); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Important iron ores', never cut) on line start, chip kept to the micro-recap. Line: FB the four grey silhouettes take their book colours one by one on cue 'لون' (LTR, book table order). RE-HOOK. Each ore keeps this colour for the whole episode (E11). On line end the ORE TABLE (g) header row 'Ore | Formula | Fe %' slides into the text panel, rows empty; the four rocks move to the stage (x 820–1800, one row).","tts_text":"أربع iron ores، وكل واحد فيهم ليه لون مختلف.","screen_text":"Four iron ores, four colours"},{"id":"s2l2","visual":"[CORE] E2c (style-video-episode v6): the four ore names are the ROWS of the book table p.16 (one row per line, ≥ 1 line apart), counted as one table item for the new-term cap; no definition card per ore. ORE TABLE (g) row 1 builds: swatch + 'Hematite' on cue 'hematite', 'Fe₂O₃' on cue 'oxide'; stage: the hematite rock grows (YK.ore({type:'hematite', label:false}) r 170) with 'Iron III oxide' under it on cue 'oxide' and tag 'blood red' on cue 'أحمر'; the other three rocks dim to 30%.","tts_text":"أولهم الـ hematite: iron تلاتة oxide، ولونه أحمر زي الدم.","screen_text":"1) Hematite · Iron III oxide · Fe₂O₃ · blood red"},{"id":"s2l3","visual":"[CORE] ORE TABLE row 1 'Fe %' cell '50–60' on cue 'خمسين'; stage: the hematite rock's %Fe gauge (o.gauge 0 → 1) on cue 'خمسين'; a small Egypt outline (bottom right of the stage, 280 px) with an 'Oasis area (Western Desert)' dot on cue 'Western'.","tts_text":"خمسين لستين في المية iron، وموجود في واحات الـ Western Desert عندنا.","screen_text":"50–60% Fe · Oasis area (Western Desert)"},{"id":"s2l4","visual":"PREREQ chem.water-of-crystallization [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · FB. Prereq YK.chip (link icon) 'Water of crystallization'. No short is published yet: a crystal lattice (YK.lattice) with blue H₂O molecules (YK.molecule) locked between its particles on YK.cue('s2l4','crystal',1) (needle 'crystal' hits 'crystallization' first); YK.lattice({rows:4, cols:6, pack:'square', color:'#8FA3BF'}) with YK.molecule({formula:'H2O'}) placed at pos(r,c) midpoints; notation '·xH₂O' on cue 'water'. Prereq chip out at line end.","tts_text":"فاكرين الـ water of crystallization؟ مية داخلة في تركيب الـ crystal نفسه.","screen_text":"Water of crystallization: water inside the crystal"},{"id":"s2l5","visual":"[CORE] ORE TABLE row 2 builds: swatch + 'Limonite' on cue 'limonite', '2Fe₂O₃·3H₂O' on cue 'formula' with '·3H₂O' blue (same blue as the s2l4 recap); stage: the limonite rock grows next to the hematite rock (hematite dims to 50%), tag 'yellow' on cue 'أصفر'.","tts_text":"تاني واحد الـ limonite: أصفر، والـ formula بتاعته فيها مية.","screen_text":"2) Limonite · 2Fe₂O₃·3H₂O · yellow"},{"id":"s2l6","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: the oxidation state of iron inside the hydrate; not asked in the unit's lessons or questions). Question in the text panel ABOVE the table (table dims to 30%); stage: the limonite formula large (mono 72) with 'Fe' boxed and '?' over it on cue 'limonite'; YK.thinkRing on the stage from cue 'وفكّروا' through the 3 s pause.","tts_text":"طب الحديد في الـ limonite: iron اتنين ولا تلاتة؟ وقّفوا وفكّروا. <long pause>","screen_text":"Limonite 2Fe₂O₃·3H₂O: iron (II) or iron (III)?","pause_after_s":3},{"id":"s2l7","visual":"[CORE] FB split (first-mentioned left): 'Fe₂O₃' (hematite rock) left, '2Fe₂O₃·3H₂O' (limonite rock) right; answer 'Iron (III)' + YK.rightMark on cue 'تلاتة'; chemical name 'Hydrated iron III oxide' on cue 'hydrated'; the blue '·3H₂O' pulses on cue 'مية'. Refutes fe.ores misconception #3 (limonite is anhydrous).","tts_text":"الإجابة تلاتة: ده hydrated iron تلاتة oxide، يعني hematite ومعاه مية.","screen_text":"Iron (III) ✓ hydrated iron III oxide: Fe₂O₃ + water"},{"id":"s2l8","visual":"[CORE] ORE TABLE row 2 'Fe %' cell '20–60' on cue 'عشرين'; stage: the limonite gauge (book range 20–60) on cue 'عشرين'; the Egypt outline returns, 'Oasis area' dot pulses on cue 'الواحات'. Book p.16. (No 40 % anywhere: the 40 % of the p.17 equation is not shown in this episode, so nothing contradicts it.)","tts_text":"ونسبته من عشرين لستين في المية iron، وبرضه في الواحات.","screen_text":"20–60% Fe · Oasis area"},{"id":"s2l9","visual":"[CORE] FB (shot change; table off screen for this line): YK.ore({type:'magnetite'}) black with its magnetic rim large on cue 'magnetite'; a small YK.magnet pulls it a little on cue 'magnetic'; tag 'black' beside it; Egypt outline dot 'Eastern Desert' on cue 'Eastern'. Book row 3.","tts_text":"تالت واحد الـ magnetite: أسود، وليه magnetic properties، في الـ Eastern Desert بتاعتنا.","screen_text":"3) Magnetite · black · magnetic properties · Eastern Desert"},{"id":"s2l10","visual":"[CORE] TP: ORE TABLE returns; row 3 builds: swatch + 'Magnetite' and 'Fe₃O₄' on cue 'magnetic' (stage label 'Magnetic iron oxide' under the rock on the same cue); 'Fe %' cell '45–70' + the rock's gauge on cue 'خمسة'.","tts_text":"واسمه magnetic iron oxide، ونسبته من خمسة وأربعين لسبعين في المية.","screen_text":"Magnetic iron oxide · Fe₃O₄ · 45–70% Fe"},{"id":"s2l11","visual":"[CORE] ORE TABLE row 4 builds: swatch + 'Siderite' on cue 'siderite', 'FeCO₃' on cue 'carbonate' (CO₃ gold); stage: YK.ore({type:'siderite'}) grows, 'Iron II carbonate' under it on cue 'carbonate', coral ✕ over a small 'oxide' tag on cue 'مش'. Refutes misconception #2 (siderite is an oxide).","tts_text":"وآخر واحد الـ siderite: iron اتنين carbonate، مش oxide خالص.","screen_text":"4) Siderite · Iron II carbonate · FeCO₃ (not an oxide)"},{"id":"s2l12","visual":"[CORE] ORE TABLE row 4 'Fe %' cell '30–42' on cue 'تلاتين'; stage: tag 'yellowish grey' on cue 'رمادي'; gauge 30–42 on cue 'تلاتين'. Book row 4 (place of deposits '---' in the book: no location drawn).","tts_text":"لونه رمادي مصفر، ونسبة الـ iron فيه من تلاتين لاتنين وأربعين.","screen_text":"Yellowish grey · 30–42% Fe"},{"id":"s2l13","visual":"[CORE] MICRO-RECAP · FB the four rocks in a row with formulas (the full table slides out left), then centred YK.takeaway ({title:'Important iron ores', line:'Fe₂O₃ · 2Fe₂O₃·3H₂O · Fe₃O₄ · FeCO₃', pulse:[{word:'FeCO₃', at:YK.cue('s2l13','siderite')}]}); the three oxide rocks pulse on cue 'تلات'.","tts_text":"الخلاصة: تلات oxides، والـ siderite carbonate لوحده.","screen_text":"Three oxides · one carbonate: siderite"},{"id":"s2l14","visual":"[CORE] SO-WHAT · FB. Big mixed rocks pile at a furnace mouth and bounce off (coral ✕) on cue 'مينفعش'. Segment chip out; in the pause: camera move into the PART 3 card.","tts_text":"بس الخام ده مينفعش يدخل الفرن كده… لازم يتجهز.","screen_text":"Straight from the mine: not ready yet","pause_after_s":2.5},{"id":"s3l1","style":"curious","visual":"PART 3/8 · fe.ore-dressing · objective: Explain the purpose of crushing, sintering and concentrating. · [CORE] Segment card in s2l14's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 3 OF 8', title:'Ore dressing: crushing, sintering, concentrating', size:100}) + objective line (Cairo 600 40, textDim); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Ore dressing: crushing, sintering, concentrating', never cut) on line start, chip kept to the micro-recap. Line: FB STAGE TRACK (b) with 'Ore dressing' lit on cue 'ore'; the big rocks, fine dust and sand of s2l14 sit on a conveyor. NEW TERM 1/3 'ore dressing'. RE-HOOK.","tts_text":"الـ ore dressing: إزاي نجهز صخر كبير، وتراب ناعم، وشوائب؟","screen_text":"Ore dressing: getting the ore ready"},{"id":"s3l2","visual":"[CORE] TP: book heading '1- Improving the physical and mechanical properties' on cue 'physical'; a 3-item list skeleton (a, b, c) appears empty on cue 'properties'. Book p.17.","tts_text":"أول جزء فيه بيحسن الـ physical والـ mechanical properties بتاعة الخام.","screen_text":"1- Improving the physical and mechanical properties"},{"id":"s3l3","visual":"[CORE] FB YK.crusher({type:'magnetite'}) (demo ore = magnetite, so the s3l10 predict on hematite powder is a new case) cycle p 0 → 1 from cue 'crushing'; small pieces fall out on cue 'نكسر'; item 'a- Crushing' fills in the list (small inset). Book p.17.","tts_text":"أولًا الـ crushing: نكسر الصخر لحجم مناسب، عشان يتعمله reduction بسهولة.","screen_text":"a- Crushing: a suitable size for easy reduction"},{"id":"s3l4","visual":"[CORE] FB: dust clouds of fine particles below the crusher and from a furnace-cleaning brush on cue 'وتنضيف'; label 'fine particles' on cue 'fine'; the dust is blown back out of a furnace mouth (coral ✕) on cue 'مينفعش'.","tts_text":"بس الـ crushing وتنضيف الأفران بيطلعوا fine particles، مينفعش تدخل الفرن.","screen_text":"Crushing + cleaning the furnace → fine particles: can't go in directly"},{"id":"s3l5","visual":"[CORE] FB YK.sinter({type:'magnetite'}) p 0 → 1 from cue 'sintering' (NEW TERM 2/3): fine particles fuse into a few even lumps on cue 'نلم'; item 'b- Sintering' fills in the list.","tts_text":"فبنعمل sintering: نلم الـ particles دي في حتت أكبر ومتشابهة.","screen_text":"b- Sintering: fine particles → larger, similar lumps"},{"id":"s3l6","visual":"[CORE] TP refutation (G40, fe.ore-dressing misconception #1): 'Sintering = melting?' with YK.wrongMark on cue 'مش' (small, < 2 s); the correct row 'collecting fine particles' on cue 'تجميع'.","tts_text":"والـ sintering مش إننا ندوّب الـ ore… ده تجميع للـ particles بس.","screen_text":"Sintering ≠ melting the ore"},{"id":"s3l7","visual":"[CORE] FB: sand grains lift out of an ore heap on cue 'بنشيل'; PIE % bar grows on cue 'فنسبة'; item 'c- Concentrating' fills in the list on cue 'concentrating' (NEW TERM 3/3).","tts_text":"تالت حاجة الـ concentrating: بنشيل أغلب الـ impurities، فنسبة الـ iron تعلى.","screen_text":"c- Concentrating: removes impurities → iron % ↑"},{"id":"s3l8","visual":"PREREQ chem.mixture-separation [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · FB. Prereq YK.chip (link icon) 'Separating mixtures'. No short is published yet: a dish of iron filings mixed with sand; a YK.magnet lifts the filings on cue 'magnet', sand stays. Prereq chip out at line end.","tts_text":"فاكرين فصل الـ mixtures؟ بنستخدم physical property، زي الـ magnet مثلًا.","screen_text":"Separating mixtures: use a physical property (a magnet)"},{"id":"s3l9","visual":"[CORE] FB YK.magSeparator (black magnetite grains, p 0 → 1 on cue 'magnetic', ore grains to the right bin, 'Impurities' to the left). Beside it, the concentrating item's sub-list, ONE METHOD PER ROW, each row on its own cue word (book order): '· surface tension' (+ small icon: water surface with floating grains) on cue 'surface', '· magnetic separation' on cue 'magnetic', '· electric separation' (+ small charged-plate icon) on cue 'electric'.","tts_text":"والفصل هنا بيبقى بالـ surface tension، أو magnetic، أو electric separation كمان.","screen_text":"Separation: surface tension, magnetic or electric"},{"id":"s3l10","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: hematite powder; the unit's questions use magnetite + sand and a sequence item). Question in the text panel; stage: a heap of red powder on cue 'بودرة'; the three item chips (crushing, sintering, concentrating) grey above it; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"الـ hematite بعد الـ crushing بقى بودرة ناعمة. أنهي process بعدها؟ وقّفوا وفكّروا. <long pause>","screen_text":"Hematite after crushing: a fine powder. Which process next?","pause_after_s":3},{"id":"s3l11","visual":"[CORE] FB: the 'Sintering' chip lights + YK.rightMark on cue 'sintering'; the powder fuses into lumps (YK.sinter, red) on cue 'يلم'.","tts_text":"الـ sintering: يلم البودرة في حتت أكبر، تنفع تدخل الفرن.","screen_text":"Sintering ✓ fine particles → larger lumps"},{"id":"s3l12","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Ore dressing: crushing, sintering, concentrating', line:'Crushing: size · sintering: lumps · concentrating: iron % ↑', pulse:[{word:'Crushing', at:YK.cue('s3l12','crushing')}, {word:'sintering', at:YK.cue('s3l12','sintering')}, {word:'concentrating', at:YK.cue('s3l12','concentrating')}]}).","tts_text":"الخلاصة: الـ crushing للحجم، والـ sintering للتجميع، والـ concentrating للنسبة.","screen_text":"Crushing: size · sintering: lumps · concentrating: iron % ↑"},{"id":"s3l13","visual":"[CORE] SO-WHAT · FB. STAGE TRACK: 'Ore dressing' splits into 'physical ✓' and 'chemical ?' on cues 'physical', 'chemical'. Segment chip out; m1 follows.","tts_text":"ده الجزء الـ physical… وقبل الجزء الـ chemical، نلم اللي فات.","screen_text":"That was the physical part. First, a quick recap.","pause_after_s":1},{"id":"m1l1","visual":"[CORE] MID-EPISODE RECAP 1 (after Parts 1-3, ~4:30) · FB. YK.flow({rtl:false, layout:'row', area:{x:96,y:380,w:1728,h:320}, node:{size:40}}); header 'So far' (Cairo 800 40). Node 1 'Iron ore' (sub '4th in the crust · impurities') lit on cue 'ores'.","tts_text":"الحديد رابع عنصر في الـ crust، وبنلاقيه ores فيها impurities كتير.","screen_text":"Iron: 4th in the crust · found as ores with impurities"},{"id":"m1l2","visual":"[CORE] Flow: node 2 'Four ores' with the Part 2 ORE TABLE shrunk inside it (names + formulas only, ≥ 32 px) and four small rocks in book colours, each lit on its cue: 'hematite', 'limonite', 'magnetite', 'siderite'.","tts_text":"أربع ores: الـ hematite والـ limonite والـ magnetite والـ siderite في الآخر.","screen_text":"Hematite · limonite · magnetite · siderite"},{"id":"m1l3","visual":"[CORE] Flow: arrow + node 3 'Ore dressing' with sub-row '1 physical: a crushing · b sintering · c concentrating' (book lists a-b-c; dots, no arrows between them), each word lit on cues 'crushing', 'sintering', 'concentrating'. Leave room in the node for sub-row 2 (roasting, Part 4). In the pause: camera move into the PART 4 card.","tts_text":"وبعدين الـ ore dressing، فيه الـ crushing والـ sintering والـ concentrating بالترتيب.","screen_text":"Ore dressing (physical): a crushing · b sintering · c concentrating","pause_after_s":2.5},{"id":"s4l1","visual":"PART 4/8 · fe.roasting · objective: Write the roasting equations that raise the iron percentage. · [CORE] Segment card in m1l3's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 4 OF 8', title:'Roasting of iron ore', size:100}) + subtitle 'drying the ore' drawn with YK.text (Cairo 800 44, textDim; actCard has no sub option) + objective line (Cairo 600 40, textDim); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Roasting of iron ore', never cut) on line start, chip kept to the micro-recap. Line: FB YK.kiln({type:'siderite', gases:[]}) heats up on cue 'نسخّن'; PIE % bar beside it rises on cue 'تعلى'; a gold 'no Fe added' tag on cue 'نضيف'. RE-HOOK (surprise).","tts_text":"نسخّن الـ ore في الهوا، ونسبة الـ iron تعلى… من غير ما نضيف حديد.","screen_text":"Heat the ore in air: iron % goes up. No iron added!"},{"id":"s4l2","visual":"[CORE] TP: 'Roasting' title on cue 'roasting' (NEW TERM 1/3) + book line 'the ore is strongly heated in air' on cue 'بيتسخن'; stage kiln flame grows. Book p.17.","tts_text":"ده اسمه roasting: الـ ore بيتسخن جامد في الهوا.","screen_text":"Roasting: the ore is strongly heated in air"},{"id":"s4l3","visual":"[CORE] TP: book heading '2- Improving the chemical properties' on cue 'chemical'; STAGE TRACK: 'chemical ?' becomes 'chemical: roasting' on cue 'الخام'.","tts_text":"وده بيحسن الـ chemical properties بتاعة الخام.","screen_text":"2- Improving the chemical properties"},{"id":"s4l4","visual":"PREREQ redox.basic [RECAP-PREREQ] (one line, ≤ 8 s, reference only; moved here from Part 6 because Parts 4–5 already use oxidation and 'roasting ≠ reduction'; tts drops the term thermal decomposition) · FB. Prereq YK.chip (link icon) 'Oxidation and reduction by oxygen'. SAME MODEL as video-short-redox.basic l2–l3: an O disc lands on a grey metal token on cue 'oxidation' + label 'oxidation: gain of oxygen' (mint); the O disc leaves it on cue 'reduction' + label 'reduction: loss of oxygen' (coral). Prereq chip out at line end. (Thermal decomposition is not recapped: s4l6 shows it as the Δ equation; tts fix drops the term.)","tts_text":"فاكرين؟ الـ oxidation إن المادة تاخد oxygen، والـ reduction إنها تخسره.","screen_text":"Oxidation: gain of oxygen · Reduction: loss of oxygen"},{"id":"s4l5","visual":"[CORE] TP: book purpose 'a) Drying the ore and expelling humidity, to increase the percentage of iron' builds on cues 'نجفف', 'iron'; stage: steam wisps leave the kiln on cue 'الرطوبة'.","tts_text":"أول هدف: نجفف الـ ore ونطلّع الرطوبة، عشان نسبة الـ iron تعلى.","screen_text":"a) Drying the ore and expelling humidity → iron % ↑"},{"id":"s4l6","visual":"[CORE] TP worked example row 1 (YK.formula 56, book p.17) builds: 'FeCO₃(s)' on cue 'siderite', '→Δ' on cue 'بالحرارة', 'FeO(s)' on cue 'oxide', '+ CO₂(g)' on cue 'carbon'; stage: the siderite rock in the kiln, a 'CO₂' gas label leaves on cue 'بيطلع'.","tts_text":"الـ siderite بالحرارة بيتكسر: يدّي iron اتنين oxide، والـ carbon dioxide بيطلع.","screen_text":"FeCO₃(s) →Δ FeO(s) + CO₂(g)"},{"id":"s4l7","visual":"[CORE] FB close-up (breaks the text-panel run s4l5–s4l8): model (e) large: two grey FeO tokens; an O disc from an air O₂ (YK.molecule 'O2') joins them on cue 'oxygen' and they merge into one red Fe₂O₃ token; equation row 2 as a full-width formula strip (YK.formula 56, y 900): '2FeO(s)' on cue 'iron', '+ ½O₂(g)' on cue 'oxygen', '→Δ Fe₂O₃(s)' + gold tag 'oxidation' on cue 'oxidation' (mint 'gain of oxygen' under it, same as the s4l4 recap).","tts_text":"والـ iron اتنين oxide بياخد oxygen من الهوا، وده oxidation واضح.","screen_text":"2FeO(s) + ½O₂(g) →Δ Fe₂O₃(s) · oxidation"},{"id":"s4l8","visual":"[CORE] TP: rows 1–2 back in the text panel (small), row 3 builds: '2Fe₂O₃·3H₂O(s)' on cue 'limonite', '+ 3H₂O(v)' on cue 'بخار' (the recap's blue H₂O leaving the lattice), '2Fe₂O₃(s)' on cue 'oxide'; stage: the limonite rock in the kiln, blue vapour leaves. (No % figures here: they come in Part 5.)","tts_text":"والـ limonite بيطلّع الـ water of crystallization بخار، ويفضل iron تلاتة oxide لوحده.","screen_text":"2Fe₂O₃·3H₂O(s) →Δ 2Fe₂O₃(s) + 3H₂O(v)"},{"id":"s4l9","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: wet hematite, not in the unit's lessons or questions). Question in the text panel; stage: a red YK.ore hematite with water drops on cue 'مبلول', entering the kiln on cue 'roasting'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"طب hematite مبلول دخل الـ roasting… إيه اللي هيطلع منه؟ وقّفوا وفكّروا. <long pause>","screen_text":"Damp hematite goes into roasting. What leaves?","pause_after_s":3},{"id":"s4l10","visual":"[CORE] FB: vapour leaves on cue 'بخار' + YK.rightMark; the dry red rock stays tagged 'Fe₂O₃' on cue 'oxide'; PIE % bar rises on cue 'فالنسبة'.","tts_text":"بخار المية بس اللي بيطلع، والـ iron تلاتة oxide بيفضل، فالنسبة تعلى.","screen_text":"Water vapour leaves ✓ Fe₂O₃ stays → iron % ↑"},{"id":"s4l11","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Roasting of iron ore', line:'Roasting: CO₂ and water leave → iron % ↑', formula:'FeCO_3 ->[Δ] FeO + CO_2', pulse:[{word:'CO₂', at:YK.cue('s4l11','carbon')}, {word:'water', at:YK.cue('s4l11','والمية')}]}).","tts_text":"الخلاصة: الـ roasting بيطلّع الـ carbon dioxide والمية، فالنسبة تعلى.","screen_text":"Roasting: CO₂ and water leave → iron % ↑"},{"id":"s4l12","visual":"[CORE] SO-WHAT · FB. PIE % bar with a gold '?' on cue 'ليه'. Segment chip out; in the pause: camera move into the PART 5 card.","tts_text":"بس ليه النسبة بتعلى بالظبط؟ يلا نحسبها.","screen_text":"But why does the iron % go up? Let's count.","pause_after_s":2.5},{"id":"s5l1","style":"curious","visual":"PART 5/8 · fe.roasting · objective: Explain why roasting raises the iron percentage and removes S and P. · [CORE] Segment card in s4l12's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 5 OF 8', title:'Roasting of iron ore', size:100}) + subtitle 'iron % and impurities' drawn with YK.text (Cairo 800 44, textDim) + objective line (Cairo 600 40, textDim); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Roasting of iron ore', never cut) on line start, chip kept to the micro-recap. Line: FB the kiln of Part 4 with PIE % bar; '?' over the bar on cue 'منين'. RE-HOOK.","tts_text":"محدش زوّد حديد… أُمّال النسبة الزيادة جت منين؟","screen_text":"No iron added: where does the extra % come from?"},{"id":"s5l2","visual":"PREREQ stoich.mass-percentage [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Mass percentage of an element'. No short is published yet: fraction card 'mass of the element / total mass × 100' builds on cues 'كتلة' and 'الكلية'. 'molar mass' would not fit the s5l11 sample calculation (50 g ÷ 80 g). Prereq chip out at line end.","tts_text":"فاكرين الـ mass percentage؟ كتلة العنصر على الكتلة الكلية، في مية.","screen_text":"Mass % = mass of the element ÷ total mass × 100"},{"id":"s5l3","visual":"[CORE] TP worked example (book p.17 values): 'FeCO₃: 48.5% iron' on cue 'تمانية'; stage: PIE % bar 48.5 on cue 'carbonate'.","tts_text":"الـ iron اتنين carbonate فيه تمانية وأربعين ونص في المية بس.","screen_text":"FeCO₃: 48.5% Fe"},{"id":"s5l4","visual":"[CORE] FB: the bar's 'rest' part shrinks as a CO₂ token leaves on cue 'بيطلع'; the 'iron' part stays fixed (gold outline) on cue 'iron'.","tts_text":"الـ carbon dioxide بيطلع، فالكتلة بتقل، وكتلة الـ iron زي ما هي.","screen_text":"CO₂ leaves → the total mass falls · the iron mass stays"},{"id":"s5l5","visual":"[CORE] TP row 'Fe₂O₃: 69.6% Fe' on cue 'oxide' (book value); stage bar re-scales to 69.6 on cue 'تسعة'.","tts_text":"وفي الآخر iron تلاتة oxide، والنسبة بقت تسعة وستين فاصلة ستة في المية.","screen_text":"Fe₂O₃: 69.6% Fe"},{"id":"s5l6","visual":"[CORE] FB split (first-mentioned left): bar 'FeCO₃ 48.5%' left, bar 'Fe₂O₃ 69.6%' right, same iron block (gold) in both, on cues 'iron', 'أصغر'.","tts_text":"نفس الـ iron، في كتلة أصغر… يبقى النسبة أعلى.","screen_text":"Same iron, smaller total mass → higher %"},{"id":"s5l7","visual":"[CORE] TP: book purpose 'b) Oxidation of some impurities such as sulphur and phosphorus' on cue 'oxidation'; stage: yellow S grains and white P grains in the ore on cues 'sulphur', 'phosphorus'.","tts_text":"تاني هدف: oxidation للـ impurities، زي الـ sulphur والـ phosphorus كمان.","screen_text":"b) Oxidation of some impurities such as sulphur and phosphorus"},{"id":"s5l8","visual":"[CORE] FB (breaks the text-panel run s5l7–s5l12): the kiln full-bleed close-up; a yellow S grain in the ore meets an O₂ molecule (YK.molecule 'O2') on cue 'oxygen'; an 'SO₂' gas tag rises out of the kiln on cue 'غاز'; equation as a full-width formula strip (YK.formula 56, y 900): 'S(s) + O₂(g)' on cue 'oxygen', '→Δ SO₂(g)' on cue 'dioxide'. Book p.17.","tts_text":"الـ sulphur بياخد oxygen، ويطلع sulphur dioxide غاز.","screen_text":"S(s) + O₂(g) →Δ SO₂(g)"},{"id":"s5l9","visual":"[CORE] TP row 2 builds: '4P(s) + 5O₂(g)' on cue 'phosphorus', '→Δ 2P₂O₅(s)' on cue 'pentoxide' (state (s) as in the book: it is NOT drawn leaving as a gas).","tts_text":"والـ phosphorus بيتأكسد هو كمان، ويبقى phosphorus pentoxide بالمعادلة دي.","screen_text":"4P(s) + 5O₂(g) →Δ 2P₂O₅(s)"},{"id":"s5l10","visual":"[CORE] FB split (E7; first-mentioned left): left 'Roasting' = the kiln, an O disc JOINS a grain (mint 'oxidation') on cue 'تسخين'; right 'Reduction?' = the s4l4 model, O disc LEAVING (dim, coral ✕ YK.wrongMark small on cue 'لأ'). Headline 'Roasting ≠ reduction' top. Refutes fe.roasting misconception #1 (G40).","tts_text":"ناس كتير فاكرة الـ roasting reduction… لأ، ده تسخين في الهوا.","screen_text":"Roasting ≠ reduction · heating in air: oxidation"},{"id":"s5l11","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: a made-up mass-% calculation; not in the unit's lessons or questions). Question in the text panel (tag 'made-up values', Cairo 600 32 textDim); stage: a 100 g ore block with a PIE % bar '50 g iron' on cue 'خمسين'; 20 g of gas tokens leave the block on cue 'عشرين'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"مية جرام ore فيهم خمسين iron، طلّع عشرين جرام غازات… النسبة كام؟ وقّفوا وفكّروا. <long pause>","screen_text":"100 g of ore holds 50 g of iron and loses 20 g of gases. New iron %?","pause_after_s":3},{"id":"s5l12","visual":"[CORE] TP: the calculation builds on cues 'خمسين', 'تمانين', 'اتنين'; YK.rightMark; stage bar re-scales 50% → 62.5%.","tts_text":"خمسين على تمانين، في مية: اتنين وستين ونص في المية.","screen_text":"50 ÷ 80 × 100 = 62.5% ✓"},{"id":"s5l13","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Roasting of iron ore', line:'Roasting: iron % ↑ · oxidation of impurities (S, P)', formula:'S + O_2 ->[Δ] SO_2', pulse:[{word:'iron', at:YK.cue('s5l13','iron')}, {word:'oxidation', at:YK.cue('s5l13','oxidation')}]}).","tts_text":"الخلاصة: الـ roasting بيعلّي نسبة الـ iron، وبيعمل oxidation للـ impurities كمان.","screen_text":"Roasting: iron % ↑ · oxidation of impurities (S, P)"},{"id":"s5l14","visual":"[CORE] SO-WHAT · FB. An Fe₂O₃ token with red O tokens (model e) on cue 'iron'; the O tokens shake on cue 'يتشال'. STAGE TRACK: 'Reduction of iron ores' lights. Segment chip out; in the pause: camera move into the PART 6 card.","tts_text":"كده عندنا iron oxide جاهز… والـ oxygen لازم يتشال منه.","screen_text":"Now: take the oxygen away from the iron oxide","pause_after_s":2.5},{"id":"s6l1","visual":"PART 6/8 · fe.blast-furnace-reduction · objective: Explain the role of coke and write the blast furnace equations. · [CORE] Segment card in s5l14's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 6 OF 8', title:'Reduction in the blast furnace', size:100}) + objective line (Cairo 600 40, textDim); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Reduction in the blast furnace', never cut) on line start, chip kept to the micro-recap. Line: FB YK.furnace({type:'blast', labels:false, flow:0, highlight:null}) full-bleed; black coke lumps fall in on cue 'coke'; a '?' between a coke lump and the Fe₂O₃ token on cue 'بيشيل'. NEW TERM 1/3 'blast furnace', 2/3 'coke'. RE-HOOK.","tts_text":"الـ blast furnace فيه coke… بس هل الـ coke هو اللي بيشيل الـ oxygen؟","screen_text":"The blast furnace burns coke. Does coke take the oxygen itself?"},{"id":"s6l2","visual":"PREREQ redox.basic [RECAP-PREREQ] (callback ≤ 8 s, the segment's only prereq line; first recapped in Part 4 s4l4; adds only the reducing agent) · TP. Prereq YK.chip (link icon) 'Oxidation and reduction by oxygen'. SAME MODEL as s4l4 / video-short-redox.basic: the O disc leaves a red Fe₂O₃ token (coral 'reduction: loss of oxygen') on cue 'oxygen'; a taker token tagged 'reducing agent' (gold) catches it on cue 'reducing'. Prereq chip out at line end.","tts_text":"فاكرين الـ reduction؟ المادة بتخسر oxygen، والـ reducing agent هو اللي بياخده.","screen_text":"Reduction: losing oxygen · reducing agent: takes the oxygen"},{"id":"s6l3","visual":"[CORE] TP: book heading 'Secondly: Reduction of Iron Ores' on cue 'reduction'; two slots 'a) blast furnace' / 'b) Midrex furnace' (b dim) on cue 'بطريقتين'. STAGE TRACK stage 2 lit.","tts_text":"ودي تاني مرحلة: reduction للـ iron ores، بطريقتين حسب الـ reducing agent المستخدم.","screen_text":"Secondly: reduction of iron ores · two methods (by the reducing agent)"},{"id":"s6l4","visual":"[CORE] FB furnace: rising gas arrows (flow 0 → 1) start on line start; TP worked example row 1 (book p.18) builds: 'C(s)' on cue 'carbon', '+ O₂(g)' on cue 'oxygen', '→Δ CO₂(g)' on cue 'dioxide'; stage: a flame at the coke lump.","tts_text":"الـ coke ده carbon، بيتحرق في الـ oxygen ويطلع carbon dioxide سخن.","screen_text":"C(s) + O₂(g) →Δ CO₂(g)"},{"id":"s6l5","visual":"[CORE] TP row 2 builds: 'CO₂(g)' on cue 'carbon', '+ C(s)' on cue 'coke', '→Δ 2CO(g)' on cue 'monoxide'.","tts_text":"والـ carbon dioxide يقابل coke سخن تاني، فيبقى carbon monoxide على طول.","screen_text":"CO₂(g) + C(s) →Δ 2CO(g)"},{"id":"s6l6","visual":"[CORE] TP row 3 builds: '3CO(g) + Fe₂O₃(s)' on cue 'monoxide'; stage: model (e): three CO tokens each lift one red O off the Fe₂O₃ token on cue 'يشيل'.","tts_text":"والـ carbon monoxide ده يشيل الـ oxygen من الـ iron تلاتة oxide كله.","screen_text":"3CO(g) + Fe₂O₃(s) → 2Fe(s) + 3CO₂(g)"},{"id":"s6l7","visual":"[CORE] TP row 3 completes: condition 'higher than 700 °C' over the arrow on cue 'سبعمية' (the only temperature in this part, book p.18), '2Fe(s)' on cue 'iron', '+ 3CO₂(g)' on cue 'dioxide'; stage: YK.furnace labels true ('> 700°C', 'Fe' out), tap stream on cue 'iron'.","tts_text":"أعلى من سبعمية درجة: يطلع iron، والـ carbon monoxide يرجع carbon dioxide تاني.","screen_text":"higher than 700 °C → 2Fe(s) + 3CO₂(g)"},{"id":"s6l8","visual":"[CORE] FB close-up of model (e): the three O tokens are counted 1-2-3 on cue 'تلاتة'; coefficient '3' in row 3 pulses gold.","tts_text":"كل carbon monoxide بياخد oxygen واحدة، فمحتاجين تلاتة.","screen_text":"Each CO takes one O: Fe₂O₃ has 3 O → 3CO"},{"id":"s6l9","visual":"[CORE] TP refutation (G40, fe.blast-furnace-reduction misconception #1): card 'Coke reduces the ore?' + YK.wrongMark on cue 'مش' (small); 'CO = reducing agent' on cue 'carbon'.","tts_text":"يعني الـ reducing agent هو الـ carbon monoxide، مش الـ coke نفسه.","screen_text":"Coke itself? ✗ CO is the reducing agent"},{"id":"s6l10","visual":"[CORE] TP: book Evaluation Q5.1 (p.26) answer card builds: 'a fuel' on cue 'fuel', 'the source of CO (the reducing agent)' on cue 'ومصدر'; stage: the coke lumps glow, CO arrows rise.","tts_text":"فالـ coke ليه دورين: fuel، ومصدر الـ carbon monoxide كمان.","screen_text":"Role of coke: a fuel + the source of CO"},{"id":"s6l11","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: the chain with O₂ removed; not in the unit's lessons or questions). Question in the text panel; stage: the furnace with the O₂ arrow crossed out on cue 'مفيش'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"تخيلوا مفيش oxygen داخل الـ furnace خالص. الـ coke هيدّي carbon monoxide؟ وقّفوا وفكّروا. <long pause>","screen_text":"No O₂ enters the furnace. Can coke still give CO?","pause_after_s":3},{"id":"s6l12","visual":"[CORE] FB (breaks the text-panel run s6l9–s6l12): full-bleed chain of three big tokens LTR 'O₂' → 'CO₂' → 'CO' (YK.molecule O2 / CO2 / CO, r 60) with coke lumps between them; YK.rightMark + 'No' on cue 'لأ'; 'O₂' crossed out on cue 'oxygen', 'CO₂' crossed out on cue 'dioxide', 'CO' crossed out on cue 'monoxide' (coral, one after the other).","tts_text":"لأ: من غير oxygen مفيش carbon dioxide، فمفيش carbon monoxide برضه.","screen_text":"No ✓ no O₂ → no CO₂ → no CO"},{"id":"s6l13","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Reduction in the blast furnace', line:'CO from coke reduces Fe₂O₃ (higher than 700 °C)', formula:'3CO + Fe_2O_3 ->[> 700 °C] 2Fe + 3CO_2', pulse:[{word:'CO', at:YK.cue('s6l13','monoxide')}, {word:'coke', at:YK.cue('s6l13','coke')}]}).","tts_text":"الخلاصة: في الـ blast furnace، الـ carbon monoxide من الـ coke بيعمل reduction للخام.","screen_text":"Blast furnace: CO from coke → reduction of Fe₂O₃ (> 700 °C)"},{"id":"s6l14","visual":"[CORE] SO-WHAT · FB. The 'b) Midrex furnace' slot glows faintly on cue 'التانية'. Segment chip out; m2 follows.","tts_text":"قبل الطريقة التانية، نلم اللي فات بسرعة.","screen_text":"Before the second method: a quick recap","pause_after_s":1},{"id":"m2l1","visual":"[CORE] MID-EPISODE RECAP 2 (after Parts 4-6, ~9:00) · FB. YK.flow row continues the m1 chain (nodes 1-3 small, dim, on the left; explicit node x/y); header 'So far'. Node 1-3 flash on cues 'ores' and YK.cue('m2l1','ore',1) (needle 'ore' hits 'ores' first). Roasting is NOT a new node: inside node 3 'Ore dressing', sub-row '2 chemical: roasting (heated in air)' lights on cue 'roasting', under sub-row '1 physical' (book p.17: roasting = ore dressing part 2).","tts_text":"من الـ ores، للـ ore dressing، وبعدين الـ roasting في الهوا.","screen_text":"Ores → ore dressing: 1 physical · 2 chemical (roasting)"},{"id":"m2l2","visual":"[CORE] Flow: the roasting sub-row of node 3 gets 'iron % ↑ · S and P oxidized' on cue 'iron'.","tts_text":"والـ roasting بيعلّي نسبة الـ iron، وبيأكسد الشوائب.","screen_text":"Roasting (ore dressing 2): iron % ↑"},{"id":"m2l3","visual":"[CORE] Flow: arrow (from the whole 'Ore dressing' node 3) + node 4 'Blast furnace' (sub 'CO from coke') on cue 'blast'. In the pause: camera move into the PART 7 card.","tts_text":"الـ carbon monoxide من الـ coke بيشيل الـ oxygen في الـ blast furnace بتاعنا.","screen_text":"Blast furnace: CO from coke removes the oxygen","pause_after_s":2.5},{"id":"s7l1","visual":"PART 7/8 · fe.midrex-reduction · objective: Explain the role of natural gas and write the Midrex equations. · [CORE] Segment card in m2l3's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 7 OF 8', title:'Reduction in the Midrex furnace', size:100}) + objective line (Cairo 600 40, textDim); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Reduction in the Midrex furnace', never cut) on line start, chip kept to the micro-recap. Line: FB YK.furnace({type:'midrex', labels:false, flow:0, highlight:null, reformer:true}) full-bleed; a coke lump crossed out (coral) on cue 'coke'. RE-HOOK.","tts_text":"طب ينفع نعمل iron من غير ولا حتة coke؟","screen_text":"Iron with no coke at all?"},{"id":"s7l2","visual":"[CORE] TP: book slot 'b) Midrex furnace' (from s6l3) lights on cue 'Midrex' (NEW TERM 1/3); 'no coke' tag on cue 'coke'. STAGE TRACK stage 2 lit.","tts_text":"أيوه: الـ Midrex furnace مش بيستخدم coke خالص.","screen_text":"b) Midrex furnace: no coke"},{"id":"s7l3","visual":"PREREQ chem.natural-gas-methane [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · FB. Prereq YK.chip (link icon) 'Natural gas (methane)'. No short is published yet: a gas pipe flame; YK.molecule CH₄ on cue 'methane'; PIE % '93% methane' (book p.18) on cue 'تلاتة'. Prereq chip out at line end.","tts_text":"بيستخدم natural gas، وده فاكرينه: أغلبه methane، تلاتة وتسعين في المية.","screen_text":"Natural gas: 93% methane, CH₄"},{"id":"s7l4","visual":"[CORE] TP worked example row 1 (book p.18) builds: '2CH₄(g)' on cue 'methane', '+ CO₂(g)' on cue 'carbon', '+ H₂O(v)' on cue 'وبخار', '→Δ' on cue 'بالحرارة'; stage: the furnace's reformer box (o.reformer) lights.","tts_text":"الـ methane بيتفاعل مع الـ carbon dioxide وبخار المية بالحرارة.","screen_text":"2CH₄(g) + CO₂(g) + H₂O(v) →Δ"},{"id":"s7l5","visual":"[CORE] FB close-up (breaks the text-panel run s7l4–s7l9): the reformer box of YK.furnace midrex large; CO tokens (YK.molecule 'CO') leave it on cue 'monoxide', H₂ tokens (YK.molecule 'H2') on cue 'hydrogen', and rise into the shaft; row 1 completes in a full-width formula strip (YK.formula 56, y 920): '→ 3CO(g)' on cue 'monoxide', '+ 5H₂(g)' on cue 'hydrogen'.","tts_text":"والناتج تلاتة carbon monoxide، وخمسة hydrogen معاهم.","screen_text":"→ 3CO(g) + 5H₂(g)"},{"id":"s7l6","visual":"[CORE] TP: bracket over '3CO + 5H₂' labelled 'water gas' on cue 'water' (NEW TERM 2/3); 'reducing agent' tag on cue 'reducing'. Book p.18 '( water gas )'. Under the bracket, draw 'water gas = CO + H_2' with YK.formula (subscript ₂, never a plain '2'), on cue 'water'.","tts_text":"الخليط ده اسمه water gas، وهو الـ reducing agent هنا.","screen_text":"Water gas: CO + H₂, the reducing agent"},{"id":"s7l7","visual":"[CORE] TP row 2 builds: '2Fe₂O₃(s)' on cue 'الخام', '+ 3CO(g)' on cue 'carbon', '+ 3H₂(g)' on cue 'hydrogen'; stage: model (e): CO and H₂ tokens each lift one O on cue 'بيشيلوا'.","tts_text":"الـ carbon monoxide والـ hydrogen، الاتنين بيشيلوا الـ oxygen من الخام.","screen_text":"2Fe₂O₃(s) + 3CO(g) + 3H₂(g) →Δ"},{"id":"s7l8","visual":"[CORE] FB: the Midrex shaft full-bleed (YK.furnace midrex, labels true, flow 1): solid Fe pellets leave the shaft bottom on cue 'iron'; 'CO₂' and 'H₂O' tags leave the top on cues 'carbon' and 'وبخار'; row 2 completes in a full-width formula strip (y 920): '4Fe(s)' on cue 'iron', '+ 3CO₂(g)' on cue 'carbon', '+ 3H₂O(v)' on cue 'وبخار'.","tts_text":"فيطلع iron، ومعاه carbon dioxide وبخار مية.","screen_text":"→ 4Fe(s) + 3CO₂(g) + 3H₂O(v)"},{"id":"s7l9","visual":"[CORE] TP refutation (G40, fe.midrex-reduction misconception #1): 'CH₄ → reduction of Fe₂O₃?' + YK.wrongMark on cue 'مش' (small); 'source of water gas' on cue 'مصدر'.","tts_text":"والـ methane نفسه مش بيعمل reduction للـ ore؛ ده مصدر الـ water gas بس.","screen_text":"Methane → reduction of the ore? ✗ It is the source of water gas"},{"id":"s7l10","visual":"[CORE] FB split (E7, first-mentioned left, identical scale): left YK.furnace blast with 'CO from coke' on cue 'coke'; right panel empty frame. Panel titles 'Blast furnace' / 'Midrex furnace'.","tts_text":"يعني الـ blast furnace بياخد الـ reducing agent من الـ coke بتاعه،","screen_text":"Blast furnace: CO from coke"},{"id":"s7l11","visual":"[CORE] FB split: right YK.furnace midrex fills with 'CO + H₂ from natural gas' on cue 'natural'; the difference (reducing agent) gold in both panels on cue 'بياخده'.","tts_text":"والـ Midrex furnace بياخده من الـ natural gas بتاعه.","screen_text":"Midrex furnace: CO + H₂ from natural gas"},{"id":"s7l12","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: magnetite in the Midrex furnace; formula Fe₃O₄ on screen only, not spoken; the 3 s pause is pause_after_s. The v1 case 'Fe₂O₃ + 3H₂ → 2Fe + 3H₂O' is not a book equation and sits against the book's Fe₂O₃ + H₂ → 2FeO at 400–700 °C, p.21). Question in the text panel; stage: one black Fe₃O₄ token with 4 red O discs on cue 'magnetite'; CO and H₂ tokens waiting on the right; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"طب لو الخام magnetite، كام carbon monoxide أو hydrogen هيشيلوا الـ oxygen كله؟ وقّفوا وفكّروا.","screen_text":"Magnetite Fe₃O₄: how many CO or H₂ to take all the oxygen?","pause_after_s":3},{"id":"s7l13","visual":"[CORE] TP: answer '4' + YK.rightMark on cue 'أربعة'; stage: two CO and two H₂ tokens each take one O on cue 'وكل' (CO → CO₂, H₂ → H₂O), the token turns grey Fe.","tts_text":"أربعة: فيه أربع ذرات oxygen، وكل carbon monoxide أو hydrogen بياخد واحدة.","screen_text":"4 ✓ Fe₃O₄ has 4 O · one per CO or H₂"},{"id":"s7l14","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Reduction in the Midrex furnace', line:'Natural gas → water gas (CO + H₂) → reduction', formula:'2Fe_2O_3 + 3CO + 3H_2 ->[Δ] 4Fe + 3CO_2 + 3H_2O', pulse:[{word:'water gas', at:YK.cue('s7l14','water')}, {word:'reduction', at:YK.cue('s7l14','reduction')}]}).","tts_text":"الخلاصة: الـ natural gas بيدّي water gas، والـ water gas بيعمل reduction للخام.","screen_text":"Natural gas → water gas (CO + H₂) → reduction"},{"id":"s7l15","visual":"[CORE] SO-WHAT · FB. Iron from both furnace panels slides to the centre on cue 'iron'; a grey 'steel?' tag on cue 'steel'. STAGE TRACK: 'Iron production' lights. Segment chip out; in the pause: camera move into the PART 8 card.","tts_text":"من الفرنين بيطلع iron… بس لسه مش steel خالص.","screen_text":"Out comes iron, not steel yet","pause_after_s":2.5},{"id":"s8l1","visual":"PART 8/8 · fe.steel-production · objective: Name the two processes of steel making and the three steel furnaces. · [CORE] Segment card in s7l15's 2.5 s pause (camera move in, no fade): YK.actCard({num:'PART 8 OF 8', title:'Iron production and steel', size:100}) + objective line (Cairo 600 40, textDim); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron production and steel', never cut) on line start, chip kept to the micro-recap. Line: FB a steel beam next to a grey iron lump; '= ?' between them on cue 'iron'. RE-HOOK.","tts_text":"طب هو الـ steel ده مجرد iron نقي؟","screen_text":"Is steel just pure iron?"},{"id":"s8l2","visual":"[CORE] TP: book heading 'Thirdly: Iron Production' on cue 'production'; two type chips 'cast iron' on cue 'cast', 'steel' on cue 'steel'. Book p.18. STAGE TRACK stage 3 lit.","tts_text":"تالت مرحلة اسمها iron production: بتطلّع الـ cast iron والـ steel وغيرهم.","screen_text":"Thirdly: iron production → cast iron and steel"},{"id":"s8l3","visual":"[CORE] TP: book line 'The steel industry depends on two essential processes' on cue 'steel'; two empty numbered slots on cue 'عمليتين'.","tts_text":"وصناعة الـ steel قايمة على عمليتين أساسيين.","screen_text":"The steel industry: two essential processes"},{"id":"s8l4","visual":"[CORE] FB: furnace iron (grey lump with sand grains) on cue 'iron'; grains lift out on cue 'نشيل'; slot 1 fills 'Removal of impurities' (inset) on cue 'impurities'.","tts_text":"الأولى: نشيل الـ impurities من الـ iron اللي طالع من الأفران.","screen_text":"1. Removal of impurities from the furnace iron"},{"id":"s8l5","visual":"[CORE] FB: small element tokens drop into the clean iron: one labelled 'C', two unlabelled (the book names no elements here) on cue 'elements'; slot 2 fills 'Addition of some elements' on cue 'نضيف'; tag 'required properties' on cue 'properties'.","tts_text":"والتانية: نضيف elements معينة، عشان الـ properties اللي محتاجينها.","screen_text":"2. Addition of some elements → the required properties"},{"id":"s8l6","visual":"[CORE] TP refutation (G40, fe.steel-production misconception #1): 'Steel = pure iron?' + YK.wrongMark on cue 'مش' (small); 'iron + added elements (e.g. carbon)' on cue 'carbon'.","tts_text":"فالـ steel مش iron نقي… ده متضاف له elements زي الـ carbon مثلًا.","screen_text":"Steel ≠ pure iron: elements are added, e.g. carbon"},{"id":"s8l7","visual":"[CORE] FB list 'Steel furnaces' (E2c v6: book list items, counted as one item for the new-term cap): three equal tiles (YK.roundRect 460×300, heat-ramp top bar, NO drawn internals: the book gives names only) build LTR; tile 1 'Oxygen converters' on cue 'oxygen'. Book p.18 list order.","tts_text":"والـ steel بيتعمل في فرن من تلاتة: الـ oxygen converters، وده أولهم.","screen_text":"Steel furnaces: 1. oxygen converters"},{"id":"s8l8","visual":"[CORE] FB list 'Steel furnaces', one row per line: tile 2 'Open-hearth furnace' on cue 'open' (needle 'open', not 'open-hearth': STT splits the hyphen). Tile 3 stays empty until s8l8b.","tts_text":"والفرن التاني: الـ open-hearth furnace، وده رقم اتنين.","screen_text":"2. open-hearth furnace"},{"id":"s8l8b","visual":"[CORE] FB list 'Steel furnaces': tile 3 'Electric furnace' on cue 'electric'; the three tiles complete the list (book p.18 order).","tts_text":"والتالت: الـ electric furnace، وبكده خلصنا التلاتة.","screen_text":"3. electric furnace"},{"id":"s8l9","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: sulphur left in furnace iron; not in the unit's lessons or questions). Question in the text panel; stage: grey iron lump with yellow S grains on cue 'sulphur'; the two process slots grey; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"لو الـ iron اللي طالع فيه sulphur، أنهي عملية من الاتنين؟ وقّفوا وفكّروا. <long pause>","screen_text":"Furnace iron still holds sulphur. Which of the two processes?","pause_after_s":3},{"id":"s8l10","visual":"[CORE] FB: slot 1 lights + YK.rightMark on cue 'نشيل'; the S grains lift out on cue 'impurities'; slot 2 pulses on cue 'نضيف'.","tts_text":"العملية الأولى: نشيل الـ impurities، وبعدين نضيف الـ elements المطلوبة.","screen_text":"1. Removal of impurities ✓"},{"id":"s8l11","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron production and steel', line:'Steel: remove impurities, add elements · oxygen converters, open-hearth, electric furnace', pulse:[{word:'impurities', at:YK.cue('s8l11','impurities')}, {word:'elements', at:YK.cue('s8l11','elements')}]}).","tts_text":"الخلاصة: الـ steel بنشيل منه impurities ونضيف elements، في فرن من التلاتة.","screen_text":"Steel: remove impurities, add elements · 3 furnaces"},{"id":"s8l12","visual":"[CORE] SO-WHAT · FB. Camera pulls out to an empty flow row. Segment chip out.","tts_text":"يلا نلم الرحلة كلها في سلسلة واحدة.","screen_text":"The whole road, from rock to steel","pause_after_s":1},{"id":"z1","visual":"[CORE] CLOSING SUMMARY · FB. YK.flow({rtl:false}) LTR in book order, nodes ≥ 32 px: node 1 'Iron ore' (sub 'suitable ore') on cue 'نبدأ' then 'suitable ore' on cue 'suitable'; the four rocks shown, hematite and magnetite lit on cues 'hematite', 'magnetite'.","tts_text":"نبدأ من iron ore يكون suitable، زي الـ hematite والـ magnetite وغيرهم.","screen_text":"Iron ore (e.g. hematite, magnetite)"},{"id":"z2","visual":"[CORE] FB flow: arrow + node 2 'Ore dressing' on cue 'dressing'; sub-row '1 physical: crushing · sintering · concentrating' (dots, no arrows: book a-b-c), words lit on cues 'crushing', 'sintering', 'concentrating'. Leave room in the node for sub-row 2 (z3).","tts_text":"وبعدين الـ ore dressing: الـ crushing، والـ sintering، والـ concentrating بالترتيب.","screen_text":"Ore dressing 1 (physical): crushing · sintering · concentrating"},{"id":"z3","visual":"[CORE] FB flow: NOT a new node: inside node 2 'Ore dressing', sub-row '2 chemical: roasting (iron % ↑ · S, P oxidized)' lights on cue 'roasting' (book p.17: roasting = ore dressing part 2). The next arrow (z4, reduction) leaves the whole 'Ore dressing' node.","tts_text":"وبعدين الـ roasting في الهوا: نسبة الـ iron بتعلى.","screen_text":"Ore dressing 2 (chemical): roasting in air → iron % ↑"},{"id":"z4","visual":"[CORE] FB flow: arrow (from the whole 'Ore dressing' node 2) + node 3 'Reduction' split in two rows (E7 order): row 1 'Blast furnace: CO from coke' on cue 'blast'.","tts_text":"الـ blast furnace بيعمل reduction بالـ carbon monoxide من الـ coke بتاعه.","screen_text":"Reduction: blast furnace (CO from coke)"},{"id":"z5","visual":"[CORE] FB flow: node 3 row 2 'Midrex furnace: CO + H₂ from natural gas' on cue 'Midrex'.","tts_text":"والـ Midrex furnace بالـ water gas من الـ natural gas بتاعه.","screen_text":"or Midrex furnace (CO + H₂ from natural gas)"},{"id":"z6","visual":"[CORE] FB flow: arrow + node 4 'Steel' (sub 'remove impurities + add elements') on cue 'steel'.","tts_text":"وفي الآخر الـ steel: نشيل الـ impurities ونضيف elements للحديد.","screen_text":"Steel: remove impurities + add elements"},{"id":"z7","visual":"[CORE] BIG QUESTION ANSWERED · FB: the cold-open rock travels along the whole flow left → right (nodes light on cues 'نجهز', 'نسخنه', 'oxygen', 'steel'); the gold tag 'How does a rock become steel?' gets ✓ on cue 'steel'.","tts_text":"إجابة سؤالنا: نجهز الصخر، نسخنه، نشيل الـ oxygen، ونعمله steel في فرن.","screen_text":"How does a rock become steel? ✓ prepare → heat → remove oxygen → steel"},{"id":"z8","visual":"[CORE] RECALL 1/3 (Parts 3-6; NEW mix of steps, not the order item of the unit's questions) · TP. YK.checkPause; four shuffled chips on the stage on cues 'reduction', 'crushing', 'roasting', 'sintering'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"رتّبوا الأربعة دول: الـ reduction، والـ crushing، والـ roasting، والـ sintering. وقّفوا وفكّروا. <long pause>","screen_text":"Arrange: reduction, crushing, roasting, sintering","pause_after_s":3},{"id":"z9","visual":"[CORE] FB (breaks the text-panel run): the chips snap into order LTR on cues 'crushing', 'sintering', 'roasting', 'reduction'; YK.rightMark.","tts_text":"الـ crushing، وبعده الـ sintering، وبعدين الـ roasting، والـ reduction في الآخر.","screen_text":"Crushing → sintering → roasting → reduction ✓"},{"id":"z10","visual":"[CORE] RECALL 2/3 (Part 6; book Evaluation Q5.1 p.26 wording) · TP. YK.checkPause; stage: blast furnace small; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"سؤال الكتاب: إيه دور الـ coke في الـ blast furnace؟ وقّفوا وفكّروا. <long pause>","screen_text":"Explain the role of coke in the blast furnace.","pause_after_s":3},{"id":"z11","visual":"[CORE] FB: CO arrows rise in the blast furnace on cue 'carbon'; answer rows 'a fuel' on cue 'fuel', 'source of CO (reducing agent)' on cue 'reducing'; YK.rightMark.","tts_text":"هو fuel، ومصدر الـ carbon monoxide، الـ reducing agent بتاعنا.","screen_text":"A fuel + the source of CO, the reducing agent ✓"},{"id":"z12","visual":"[CORE] RECALL 3/3 (Part 7; book Evaluation Q5.2 p.26 wording) · TP. YK.checkPause; stage: Midrex furnace small; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"وآخر سؤال: دور الـ natural gas في الـ Midrex furnace؟ وقّفوا وفكّروا. <long pause>","screen_text":"Explain the role of natural gas in the Midrex furnace.","pause_after_s":3},{"id":"z13","visual":"[CORE] FB: the reformer lights, CO and H₂ tokens rise on cues 'carbon', 'hydrogen'; answer row 'source of water gas (CO + H₂), the reducing agent' on cue 'water'; YK.rightMark.","tts_text":"مصدر الـ water gas: الـ carbon monoxide والـ hydrogen، الـ reducing agent بتاعه.","screen_text":"Source of water gas (CO + H₂), the reducing agent ✓"},{"id":"z14","visual":"[TRIM-IF-OVER 15:00] TEASER (labelled last line only) · FB; label 'Next episode:' (Cairo 800 40, textDim) + 'Alloys and their types' (Cairo 1000 64) on cue 'alloys'. No subscribe. 0.8 s tail.","tts_text":"الحلقة الجاية: الـ alloys، وأنواعها المختلفة.","screen_text":"Next episode: Alloys and their types"}],"logline":"Egypt made iron two ways, a blast furnace in Helwan and a Midrex furnace in Dekheila: how does a rock become steel? Eight parts in the book's order (pp.16-18): where iron is found and what makes an ore suitable, the four ores (formula, colour, iron %), ore dressing (crushing, sintering, concentrating), roasting (the book's equations and why the iron % rises; oxidation of S and P), reduction by CO from coke in the blast furnace (above 700 °C) and by water gas from natural gas in the Midrex furnace, then the two processes and three furnaces of steel 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أهم metal في الـ heavy industries\nبس بيطلع من الأرض صخر\nومصر عملت حديد بطريقتين الـ blast furnace\nفي حلوان والـ Midrex furnace في الدخيلة\nطب إزاي حتة صخر بتبقى steel في الآخر\nالحلقة دي عن الـ iron ores والـ extraction\nبتاع الحديد منها\nبس هل الحديد أكتر عنصر في الـ crust بتاعة\nالأرض\nلأ قبله الـ oxygen والـ silicon والـ\naluminum وبعدهم الحديد\nخمسة في المية من كتلة الـ crust وبيزيد كل\nما نقرب للـ core جوه\nالحديد النقي تسعين في المية بس في الـ\nmeteorites من الفضا\nفاكرين الـ compound فيه elements متحدة\nوالـ mixture حاجات متخلطة بس\nوفي الـ crust بيبقى ore فيه iron compounds\nأغلبها oxides متخلطة مع impurities كتير\nوالـ suitability بتاعة الـ ore بتعتمد على\nنسبة الـ iron فيه\nوعلى الـ impurities والـ harmful elements\nزي الـ sulphur والـ phosphorus والـ\narsenic كمان\nطب ore فيه iron أكتر بس معاه arsenic أكيد\nsuitable وقّفوا وفكّروا\nمش أكيد الـ harmful elements بتفرق مش نسبة\nالـ iron بس\nالخلاصة رابع عنصر في الـ crust والـ\nsuitability ليها تلات عوامل\nطب إيه الـ iron compounds اللي في الـ ores\nدي\nأربع iron ores وكل واحد فيهم ليه لون مختلف\nأولهم الـ hematite iron تلاتة oxide ولونه\nأحمر زي الدم\nخمسين لستين في المية iron وموجود في واحات\nالـ Western Desert عندنا\nفاكرين الـ water of crystallization مية\nداخلة في تركيب الـ crystal نفسه\nتاني واحد الـ limonite أصفر والـ formula\nبتاعته فيها مية\nطب الحديد في الـ limonite iron اتنين ولا\nتلاتة وقّفوا وفكّروا\nالإجابة تلاتة ده hydrated iron تلاتة oxide\nيعني hematite ومعاه مية\nونسبته من عشرين لستين في المية iron وبرضه\nفي الواحات\nتالت واحد الـ magnetite أسود وليه magnetic\nproperties في الـ Eastern Desert بتاعتنا\nواسمه magnetic iron oxide ونسبته من خمسة\nوأربعين لسبعين في المية\nوآخر واحد الـ siderite iron اتنين\ncarbonate مش oxide خالص\nلونه رمادي مصفر ونسبة الـ iron فيه من\nتلاتين لاتنين وأربعين\nالخلاصة تلات oxides والـ siderite\ncarbonate لوحده\nبس الخام ده مينفعش يدخل الفرن كده لازم\nيتجهز\nالـ ore dressing إزاي نجهز صخر كبير وتراب\nناعم وشوائب\nأول جزء فيه بيحسن الـ physical والـ\nmechanical properties بتاعة الخام\nأولًا الـ crushing نكسر الصخر لحجم مناسب\nعشان يتعمله reduction بسهولة\nبس الـ crushing وتنضيف الأفران بيطلعوا\nfine particles مينفعش تدخل الفرن\nفبنعمل sintering نلم الـ particles دي في\nحتت أكبر ومتشابهة\nوالـ sintering مش إننا ندوّب الـ ore ده\nتجميع للـ particles بس\nتالت حاجة الـ concentrating بنشيل أغلب الـ\nimpurities فنسبة الـ iron تعلى\nفاكرين فصل الـ mixtures بنستخدم physical\nproperty زي الـ magnet مثلًا\nوالفصل هنا بيبقى بالـ surface tension أو\nmagnetic أو electric separation كمان\nالـ hematite بعد الـ crushing بقى بودرة\nناعمة أنهي process بعدها وقّفوا وفكّروا\nالـ sintering يلم البودرة في حتت أكبر تنفع\nتدخل الفرن\nالخلاصة الـ crushing للحجم والـ sintering\nللتجميع والـ concentrating للنسبة\nده الجزء الـ physical وقبل الجزء الـ\nchemical نلم اللي فات\nالحديد رابع عنصر في الـ crust وبنلاقيه\nores فيها impurities كتير\nأربع ores الـ hematite والـ limonite والـ\nmagnetite والـ siderite في الآخر\nوبعدين الـ ore dressing فيه الـ crushing\nوالـ sintering والـ concentrating بالترتيب\nنسخّن الـ ore في الهوا ونسبة الـ iron تعلى\nمن غير ما نضيف حديد\nده اسمه roasting الـ ore بيتسخن جامد في\nالهوا\nوده بيحسن الـ chemical properties بتاعة\nالخام\nفاكرين الـ oxidation إن المادة تاخد oxygen\nوالـ reduction إنها تخسره\nأول هدف نجفف الـ ore ونطلّع الرطوبة عشان\nنسبة الـ iron تعلى\nالـ siderite بالحرارة بيتكسر يدّي iron\nاتنين oxide والـ carbon dioxide بيطلع\nوالـ iron اتنين oxide بياخد oxygen من\nالهوا وده oxidation واضح\nوالـ limonite بيطلّع الـ water of\ncrystallization بخار ويفضل iron تلاتة\noxide لوحده\nطب hematite مبلول دخل الـ roasting إيه\nاللي هيطلع منه وقّفوا وفكّروا\nبخار المية بس اللي بيطلع والـ iron تلاتة\noxide بيفضل فالنسبة تعلى\nالخلاصة الـ roasting بيطلّع الـ carbon\ndioxide والمية فالنسبة تعلى\nبس ليه النسبة بتعلى بالظبط يلا نحسبها\nمحدش زوّد حديد أُمّال النسبة الزيادة جت\nمنين\nفاكرين الـ mass percentage كتلة العنصر على\nالكتلة الكلية في مية\nالـ iron اتنين carbonate فيه تمانية\nوأربعين ونص في المية بس\nالـ carbon dioxide بيطلع فالكتلة بتقل\nوكتلة الـ iron زي ما هي\nوفي الآخر iron تلاتة oxide والنسبة بقت\nتسعة وستين فاصلة ستة في المية\nنفس الـ iron في كتلة أصغر يبقى النسبة أعلى\nتاني هدف oxidation للـ impurities زي الـ\nsulphur والـ phosphorus كمان\nالـ sulphur بياخد oxygen ويطلع sulphur\ndioxide غاز\nوالـ phosphorus بيتأكسد هو كمان ويبقى\nphosphorus pentoxide بالمعادلة دي\nناس كتير فاكرة الـ roasting reduction لأ\nده تسخين في الهوا\nمية جرام ore فيهم خمسين iron طلّع عشرين\nجرام غازات النسبة كام وقّفوا وفكّروا\nخمسين على تمانين في مية اتنين وستين ونص في\nالمية\nالخلاصة الـ roasting بيعلّي نسبة الـ iron\nوبيعمل oxidation للـ impurities كمان\nكده عندنا iron oxide جاهز والـ oxygen لازم\nيتشال منه\nالـ blast furnace فيه coke بس هل الـ coke\nهو اللي بيشيل الـ oxygen\nفاكرين الـ reduction المادة بتخسر oxygen\nوالـ reducing agent هو اللي بياخده\nودي تاني مرحلة reduction للـ iron ores\nبطريقتين حسب الـ reducing agent المستخدم\nالـ coke ده carbon بيتحرق في الـ oxygen\nويطلع carbon dioxide سخن\nوالـ carbon dioxide يقابل coke سخن تاني\nفيبقى carbon monoxide على طول\nوالـ carbon monoxide ده يشيل الـ oxygen من\nالـ iron تلاتة oxide كله\nأعلى من سبعمية درجة يطلع iron والـ carbon\nmonoxide يرجع carbon dioxide تاني\nكل carbon monoxide بياخد oxygen واحدة\nفمحتاجين تلاتة\nيعني الـ reducing agent هو الـ carbon\nmonoxide مش الـ coke نفسه\nفالـ coke ليه دورين fuel ومصدر الـ carbon\nmonoxide كمان\nتخيلوا مفيش oxygen داخل الـ furnace خالص\nالـ coke هيدّي carbon monoxide وقّفوا\nوفكّروا\nلأ من غير oxygen مفيش carbon dioxide فمفيش\ncarbon monoxide برضه\nالخلاصة في الـ blast furnace الـ carbon\nmonoxide من الـ coke بيعمل reduction للخام\nقبل الطريقة التانية نلم اللي فات بسرعة\nمن الـ ores للـ ore dressing وبعدين الـ\nroasting في الهوا\nوالـ roasting بيعلّي نسبة الـ iron وبيأكسد\nالشوائب\nالـ carbon monoxide من الـ coke بيشيل الـ\noxygen في الـ blast furnace بتاعنا\nطب ينفع نعمل iron من غير ولا حتة coke\nأيوه الـ Midrex furnace مش بيستخدم coke\nخالص\nبيستخدم natural gas وده فاكرينه أغلبه\nmethane تلاتة وتسعين في المية\nالـ methane بيتفاعل مع الـ carbon dioxide\nوبخار المية بالحرارة\nوالناتج تلاتة carbon monoxide وخمسة\nhydrogen معاهم\nالخليط ده اسمه water gas وهو الـ reducing\nagent هنا\nالـ carbon monoxide والـ hydrogen الاتنين\nبيشيلوا الـ oxygen من الخام\nفيطلع iron ومعاه carbon dioxide وبخار مية\nوالـ methane نفسه مش بيعمل reduction للـ\nore ده مصدر الـ water gas بس\nيعني الـ blast furnace بياخد الـ reducing\nagent من الـ coke بتاعه\nوالـ Midrex furnace بياخده من الـ natural\ngas بتاعه\nطب لو الخام magnetite كام carbon monoxide\nأو hydrogen هيشيلوا الـ oxygen كله وقّفوا\nوفكّروا\nأربعة فيه أربع ذرات oxygen وكل carbon\nmonoxide أو hydrogen بياخد واحدة\nالخلاصة الـ natural gas بيدّي water gas\nوالـ water gas بيعمل reduction للخام\nمن الفرنين بيطلع iron بس لسه مش steel خالص\nطب هو الـ steel ده مجرد iron نقي\nتالت مرحلة اسمها iron production بتطلّع\nالـ cast iron والـ steel وغيرهم\nوصناعة الـ steel قايمة على عمليتين أساسيين\nالأولى نشيل الـ impurities من الـ iron\nاللي طالع من الأفران\nوالتانية نضيف elements معينة عشان الـ\nproperties اللي محتاجينها\nفالـ steel مش iron نقي ده متضاف له\nelements زي الـ carbon مثلًا\nوالـ steel بيتعمل في فرن من تلاتة الـ\noxygen converters وده أولهم\nوالفرن التاني الـ open-hearth furnace وده\nرقم اتنين\nوالتالت الـ electric furnace وبكده خلصنا\nالتلاتة\nلو الـ iron اللي طالع فيه sulphur أنهي\nعملية من الاتنين وقّفوا وفكّروا\nالعملية الأولى نشيل الـ impurities وبعدين\nنضيف الـ elements المطلوبة\nالخلاصة الـ steel بنشيل منه impurities\nونضيف elements في فرن من التلاتة\nيلا نلم الرحلة كلها في سلسلة واحدة\nنبدأ من iron ore يكون suitable زي الـ\nhematite والـ magnetite وغيرهم\nوبعدين الـ ore dressing الـ crushing والـ\nsintering والـ concentrating بالترتيب\nوبعدين الـ roasting في الهوا نسبة الـ iron\nبتعلى\nالـ blast furnace بيعمل reduction بالـ\ncarbon monoxide من الـ coke بتاعه\nوالـ Midrex furnace بالـ water gas من الـ\nnatural gas بتاعه\nوفي الآخر الـ steel نشيل الـ impurities\nونضيف elements للحديد\nإجابة سؤالنا نجهز الصخر نسخنه نشيل الـ\noxygen ونعمله steel في فرن\nرتّبوا الأربعة دول الـ reduction والـ\ncrushing والـ roasting والـ sintering\nوقّفوا وفكّروا\nالـ crushing وبعده الـ sintering وبعدين\nالـ roasting والـ reduction في الآخر\nسؤال الكتاب إيه دور الـ coke في الـ blast\nfurnace وقّفوا وفكّروا\nهو fuel ومصدر الـ carbon monoxide الـ\nreducing agent بتاعنا\nوآخر سؤال دور الـ natural gas في الـ\nMidrex furnace وقّفوا وفكّروا\nمصدر الـ water gas الـ carbon monoxide\nوالـ hydrogen الـ reducing agent بتاعه\nالحلقة الجاية الـ alloys وأنواعها المختلفة","countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"series_id":"chem-s3-en.ch1#sessions","episode_no":6,"episode_count":9,"lessons":["chem-s3-en.lesson-chem.water-of-crystallization","chem-s3-en.lesson-fe.blast-furnace-reduction","chem-s3-en.lesson-fe.midrex-reduction","chem-s3-en.lesson-fe.occurrence","chem-s3-en.lesson-fe.ore-dressing","chem-s3-en.lesson-fe.ores","chem-s3-en.lesson-fe.roasting","chem-s3-en.lesson-fe.steel-production","chem-s3-en.lesson-stoich.mass-percentage"]},{"id":"chem-s3-en.video-episode-alloys","kind":"episode","version":1,"ord":420,"content_lang":"ar-EG","primary_concept_id":"alloy.definition-preparation","concepts":[{"concept_id":"alloy.definition-preparation","role":"primary"},{"concept_id":"alloy.intermetallic","role":"secondary"},{"concept_id":"alloy.interstitial","role":"secondary"},{"concept_id":"alloy.substitutional","role":"secondary"}],"title":"Alloys and their types","payload":{"title":"Alloys and their types","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"16:9","format":"episode","script":[{"id":"c1","visual":"[CORE] COLD OPEN · FB. EPISODE MODELS (reuse in every part, same colour and position, E11): (a) LATTICE = YK.lattice (lib/chem.js) pack 'square', host atoms Fe steel grey '#8FA3BF' in compact close rows (book fig 1-5 a); slip: the top layers slide right on a gold dashed slip plane (fig 1-5 b); insert: small carbon atoms (scale 0.45, colour '#FFC94D' gold) in the spaces (fig 1-5 c) with blocked:true (the slide springs back); substitute: same-size Cr atoms (scale 1, teal '#2DE2E6') / Ni atoms (scale 1, '#7FE3A0') in the places of some Fe atoms; compound: ratio [3,1] ordered Fe₃C pattern (colour '#FF7AB6', formula tag) for the intermetallic. (b) HAMMER = YK.hammer from the left; its impact drives the lattice slip. (c) CELL = electro-deposition cell: YK.beaker of kit-neutral solution (G45: no solution or ion colours), YK.icon 'battery' on top, object on the − terminal labelled 'cathode', metal plate on +; ions = small YK.atomDisc dots carrying their symbol + '+' badge (Cu, Zn, Sn, Ni, Cr; identity colour = YK.atomColor, the LETTER identifies them); ions drift to the object and become a coat of mixed lettered dots. (d) MELT = a crucible over a flame (two ingots melt into one swirled liquid, then cool to one solid bar). (e) SWAP = YK.formula 56: two element tiles with their valency above, crossing arrows, the swapped subscripts, then the simplified formula. (f) RADIUS BAR = horizontal bars from the book table p.12 (for illustration), Cairo 800 36 labels, values in JetBrains Mono. No spoken references to other videos; prerequisite recaps reuse the visual model of their short (E2b): chem.metal-properties = YK.hammer drives YK.lattice slip → sheet → wire; chem.valency-formulas = valency numbers arc across and swap into the subscript slots. Shot: a bar of pure iron (steel grey) under a press bends easily (frame 0 already on screen, drift ≤ 2%); tag 'Pure iron' on line start, 'relatively soft' on cue 'طري', second row 'no industrial importance' on cue 'أهمية' (book p.20, Properties of iron).  KIT MAP (lib/episode.js; template must also load lib/short.js, lib/chem.js, lib/matter.js, lib/lab.js, lib/flow.js): segment cards = YK.partCard (no 'sub' field: the part's angle lives in the objective); prereq chip = YK.prereqChip; PREDICT / QUICK CHECK / RECALL = YK.predictCard({kind, q: screen_text}) (think ring included, only the question during the silence) + YK.answerSlot for the answer; misconception rows = YK.mythLine (coral, smaller than the fix); micro-recaps = YK.takeaway centred (full-bleed) as written, pulse words are SINGLE words of the card (multi-word pulses never fire). Text-panel (TP) shots never more than 3 in a row: lines marked FB in this director pass break the runs.","tts_text":"الحديد النقي طري نسبيًا، وملوش أهمية في الصناعة لوحده.","screen_text":"Pure iron: relatively soft · no industrial importance"},{"id":"c2","visual":"[CORE] FB (shot change): a train runs over railway tracks seen low from the side; the track glints on cue 'قضبان'; headline top-left on line start.","tts_text":"أمّال قضبان السكة الحديد اللي شايلة القطر معمولة من إيه؟","screen_text":"So what are railway tracks made of?"},{"id":"c3","visual":"[CORE] FB: label 'ferromanganese alloy' on the track on cue 'ferromanganese' (book p.6: 'Ferromanganese alloy is used in railway track, because it is harder than steel', te-uses, Unit 2); a hardness bar 'steel' < 'ferromanganese' grows on cue 'أصلب'; 'steel' bar label on cue 'steel'.","tts_text":"مش حديد نقي… دي ferromanganese alloy، أصلب من الـ steel كمان.","screen_text":"Railway tracks: ferromanganese alloy, harder than steel"},{"id":"c4","style":"curious","visual":"[CORE] BIG QUESTION · FB. Previous shot dims to 30%; card centred (Cairo 1000 84) 'Why is steel harder than pure iron?' on line start, 'steel' gold on cue 'steel'; held through the pause, then shrinks to a gold tag top-right (answered in s3 and z6).","tts_text":"طب ليه الـ steel نفسه أصلب من الحديد النقي؟","screen_text":"Why is steel harder than pure iron?","pause_after_s":1},{"id":"t1","visual":"[CORE] TITLE CARD (≤ 4 s from line start). YK.titleCard({title:'Alloys and their types', chip:'Unit 7', subtitle:'Chapter 1: Transition Elements'}) Cairo 1000 ≤ 120; 'alloys' gold on cue 'alloys'; parts row under it (YK.para Cairo 800 32, maxWidth 800): 1 Definition · 2 Preparation · 3 Interstitial alloys · 4 Substitutional alloys · 5 Intermetallic alloys (five parts; every segment card says 'of 5'). Then camera move (1.2 s, no fade) onto item 1, which grows into the PART 1 card.","tts_text":"الحلقة دي عن الـ alloys، وأنواعها التلاتة.","screen_text":"Alloys and their types","pause_after_s":2.5},{"id":"s1l1","style":"curious","visual":"PART 1/5 · alloy.definition-preparation · objective: Define an alloy and give the book's examples. · [CORE] Segment card in t1's 2.5 s pause (camera move in, no fade): YK.partCard({num:1, of:5, title:'Alloys: definition and preparation', objective:'Define an alloy and give the book's examples', at: cueEnd(previous line)+0.1, collapse: YK.cue('s1l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Alloys: definition and preparation', never cut) on line start, chip kept to the micro-recap. Line: FB two ingots (grey, copper-brown) slide together on line start; a '?' on cue 'metals'. RE-HOOK.","tts_text":"هي الـ alloy لازم تبقى metals بس؟","screen_text":"An alloy: only metals?"},{"id":"s1l2","visual":"PREREQ chem.metal-properties [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Properties of metals and non-metals' under the segment chip. Stage, same model as video-short-chem.metal-properties: a metal block glints on cue 'بتلمع'; YK.hammer strikes and its impact drives YK.lattice slip, the block spreads into a sheet on cue 'malleable'; the sheet is pulled into a wire on cue 'ductile'; a dull black carbon lump (graphite grey) tagged 'non-metal' on cue 'non-metals'. Labels on cue: 'shiny', 'malleable', 'ductile'. Prereq chip out at line end.","tts_text":"فاكرين؟ الـ metals بتلمع، وهي malleable و ductile، والـ non-metals غالبًا لأ.","screen_text":"Metals: shiny, malleable, ductile · non-metals: mostly not"},{"id":"s1l3","visual":"[CORE] TP DEFINITION CARD (E3a, the part's one card) YK.termCard({term:'Alloy', def:'Alloys are usually formed from two metals or more, and may consist of a metal and a non-metal such as carbon (steel).', keys:['two metals or more','a metal and a non-metal']}) builds in two halves: first half on cue 'alloys' (NEW TERM 1/3 'alloy'), 'two metals or more' gold on cue 'اتنين'; stage: two ingots melt into one bar (MELT model, small).","tts_text":"الـ alloys عادةً بتتكون من اتنين metals أو أكتر.","screen_text":"Alloys: usually formed from two metals or more"},{"id":"s1l4","visual":"[CORE] E2c (style-video-episode v6): the four ferro-alloys are the ITEMS of the book's list p.19 (one per line, each on its own line, no definition card per item), counted as one new term (2/3). TP list 'Examples (p.19)' builds item 1 'Ferrochromium (Fe + Cr)' on cue 'ferrochromium'; a gold 'ferro- = iron' tag on cue 'حديد' (not 'ferro': substring of 'ferrochromium'). Stage: LATTICE small, grey Fe atoms with a few teal Cr atoms (no type named yet).","tts_text":"زي الـ ferrochromium، وكلمة ferro يعني حديد.","screen_text":"Ferrochromium (ferro- = iron)"},{"id":"s1l5","visual":"[CORE] FB (shot change, breaks the text-panel run): the cold-open railway track returns full-bleed on cue 'قضبان' (callback), tag 'Ferromanganese (Fe + Mn)' on the rail on cue 'ferromanganese'; the E2c list (item 2 added on the same cue) is back in the text panel on s1l6.","tts_text":"والـ ferromanganese اللي في قضبان السكة الحديد.","screen_text":"Ferromanganese"},{"id":"s1l6","visual":"[CORE] E2c list item 3 'Ferrovanadium (Fe + V)' on cue 'ferrovanadium'; stage: one violet V atom per few Fe atoms on cue 'جواه'.","tts_text":"والـ ferrovanadium، حديد مع vanadium جواه.","screen_text":"Ferrovanadium"},{"id":"s1l7","visual":"[CORE] E2c list item 4 'Ferronickel (Fe + Ni)' on cue 'ferronickel'; on cue 'metals' all four items get a small 'metal + metal' tag.","tts_text":"والـ ferronickel، حديد مع nickel… كلهم metals مع بعض.","screen_text":"Ferronickel"},{"id":"s1l8","visual":"[CORE] FB (shot change): the pure iron bar of c1 next to a ferromanganese track piece; a 'hardness' gauge rises on cue 'hardness'; tag 'properties change' on cue 'نغيّر' (book p.20: iron alloys produced with specific properties suitable for many uses).","tts_text":"وليه نخلط أصلًا؟ عشان نغيّر خواص الـ metal، زي الـ hardness بتاعته.","screen_text":"Why mix? To change the metal's properties (e.g. hardness)"},{"id":"s1l9","visual":"[CORE] TP: misconception row 'Alloys contain only metals' + small YK.wrongMark on cue 'فاكرة' (said once, small, < 2 s; G40 / R11; concept misconception #1).","tts_text":"ناس كتير فاكرة إن الـ alloy لازم يبقى metals بس.","screen_text":"Common mistake: alloys contain only metals ✗"},{"id":"s1l10","visual":"[CORE] FB (shot change, breaks the text-panel run): LATTICE grey Fe with gold carbon atoms (insert, no type named yet) on cue 'steel'; tag 'carbon: non-metal' on cue 'non-metal'; the definition card's second half 'and may consist of a metal and a non-metal such as carbon (steel)' returns in the corner with YK.rightMark on cue 'alloy'.","tts_text":"لأ… الـ steel فيه carbon، وهو non-metal، وبرضه alloy عادي.","screen_text":"May consist of a metal and a non-metal: steel (iron + carbon)"},{"id":"s1l11","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: one pure metal; not in the episode, the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: a gold bar tagged '24 carat = pure gold' on cue 'gold'; YK.thinkRing on the stage from cue 'وفكّروا' through the 3 s pause.","tts_text":"طب الـ gold عيار أربعة وعشرين، يعني صافي… ده alloy؟ وقّفوا وفكّروا.","screen_text":"Pure gold (24 carat): an alloy?","pause_after_s":3},{"id":"s1l12","visual":"[CORE] FB split (E7): left the single gold bar with YK.wrongMark on cue 'لأ'; right a two-colour ingot (two metals) with YK.rightMark on cue 'اتنين'.","tts_text":"لأ: ده metal واحد بس، والـ alloy محتاج اتنين أو أكتر.","screen_text":"No ✗ one metal only: an alloy needs two elements or more"},{"id":"s1l13","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Alloys: definition and preparation', line:'Two metals or more, or a metal + a non-metal (steel)', pulse:[{word:'metals', at:YK.cue('s1l13','metals')}, {word:'non-metal', at:YK.cue('s1l13','non-metal')}]}).","tts_text":"الخلاصة: الـ alloy، اتنين metals أو أكتر، أو metal مع non-metal كمان.","screen_text":"Alloy: two metals or more, or a metal + a non-metal"},{"id":"s1l14","visual":"[CORE] SO-WHAT · FB. Two solid ingots bump into each other and stay apart on cue 'نخلط'. Segment chip stays (same concept); in the pause: camera move into the PART 2 card.","tts_text":"طب إزاي نخلط الحاجات دي ببعض أصلًا؟","screen_text":"How do we mix them?","pause_after_s":2.5},{"id":"s2l1","visual":"PART 2/5 · alloy.definition-preparation · objective: Describe the two methods of preparing alloys. · [CORE] Segment card in s1l14's 2.5 s pause (camera move in, no fade): YK.partCard({num:2, of:5, title:'Alloys: definition and preparation', objective:'Describe the two methods of preparing alloys', at: cueEnd(previous line)+0.1, collapse: YK.cue('s2l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Alloys: definition and preparation', never cut) on line start, chip kept to the micro-recap. Line: FB two solid ingots knock together on cue 'صلبين', nothing mixes; a '?' on cue 'هيتخلطوا'. RE-HOOK.","tts_text":"اتنين metals صلبين… هيتخلطوا إزاي وهما حتت ناشفة كده؟","screen_text":"Two solid metals: how do we mix them?"},{"id":"s2l2","visual":"[CORE] FB MELT model: TP header 'Preparation of alloys' + item '1. By melting' on cue 'melting'; stage: the two ingots slide into a crucible and melt into one swirling liquid on cue 'ندوّب'.","tts_text":"أول طريقة: الـ melting، ندوّب الـ metals مع بعض.","screen_text":"1. By melting: melt the metals together"},{"id":"s2l3","visual":"[CORE] MELT: the liquid pours into a mould on cue 'نسيبهم'; a slow thermometer falls on cue 'بالتدريج'; one solid two-tone bar on cue 'يجمدوا'. Book p.19 wording on screen.","tts_text":"وبعدين نسيبهم يبردوا بالراحة، بالتدريج، لحد ما يجمدوا.","screen_text":"…and leave them to cool gradually"},{"id":"s2l4","visual":"[CORE] MELT close-up: grey and copper-brown atoms swirl together in the liquid on cue 'سايلين' (approved lesson-alloy.definition-preparation: 'The metals mix while they are liquid').","tts_text":"وهما سايلين، الذرات بتتخلط كويس قوي ببعضها.","screen_text":"Liquid metals mix well"},{"id":"s2l5","visual":"[CORE] QUICK CHECK (mid-segment, ≥ 1 s pause, E1a) · YK.predictCard({kind:'QUICK CHECK', q: screen_text}) in the text panel; stage: crucible with grey and copper-brown liquid on cue 'zinc'; YK.thinkRing through the 1.5 s pause.","tts_text":"سؤال سريع: zinc و copper دايبين مع بعض، وبردوا… alloy ولا لأ؟","screen_text":"Quick check: zinc and copper melted together. Alloy?","pause_after_s":1.5},{"id":"s2l6","visual":"[CORE] TP answer 'Alloy ✓' with YK.rightMark on cue 'أيوه'; the cooled bar takes a gold-yellow brass tint, tag 'brass (Cu + Zn)' on cue 'brass' (NEW TERM 1/3 'brass').","tts_text":"أيوه alloy، واسمه brass، وهنقابله تاني دلوقتي.","screen_text":"Alloy ✓ (brass: Cu + Zn)"},{"id":"s2l7","visual":"PREREQ chem.electroplating-basic [RECAP-PREREQ] (2 lines s2l7–s2l8, ≤ 18 s together, reference only; folds the depth-2 idea phys.electric-current into 'current'). Prereq YK.chip (link icon) 'Electroplating'. FB CELL model: battery + beaker on cue 'electroplating'; a current arrow along the wire on cue 'current'; '+' ion dots in the solution on cue 'ions'.","tts_text":"فاكرين الـ electroplating؟ بنعدّي electric current في محلول، فيه metal ions ذايبة.","screen_text":"Electroplating: an electric current through a solution of metal ions"},{"id":"s2l8","visual":"PREREQ chem.electroplating-basic (line 2/2) · CELL: the object on the − terminal tagged 'cathode' on cue 'cathode'; one ion gains 'e⁻' and turns into a metal atom on its surface on cue 'electrons'; tag 'reduction' on cue 'reduction'; tag 'the object being plated' on cue 'بنطليها'. Prereq chip out at line end.","tts_text":"والـ ions بتاخد electrons عند الـ cathode، مكان الـ reduction، وهو الحاجة اللي بنطليها.","screen_text":"Cathode: where reduction happens = the object being plated"},{"id":"s2l9","visual":"[CORE] TP item '2. By electro-deposition' on cue 'electro-deposition' (NEW TERM 2/3); 'at the same time' gold on cue 'الوقت'; stage: CELL with two kinds of ion dots.","tts_text":"تاني طريقة: الـ electro-deposition، نرسّب اتنين metals أو أكتر في نفس الوقت.","screen_text":"2. By electro-deposition: two metals or more at the same time"},{"id":"s2l10","visual":"[CORE] FB (shot change): CELL close-up, an iron door handle hangs on the − terminal on cue 'مقابض'; label 'brass (Cu + Zn)' on cue 'brass'. Book example p.19.","tts_text":"زي ما بنطلي مقابض الحديد بالـ brass، يعني copper و zinc مع بعض.","screen_text":"Iron handles plated with brass (Cu + Zn)"},{"id":"s2l11","visual":"[CORE] CELL: lettered 'Cu⁺'-style dots (YK.atomDisc el 'Cu', '2+' badge) on cue 'copper', lettered 'Zn' dots on cue 'zinc'; both drift to the handle (cathode) together.","tts_text":"من محلول واحد فيه copper ions و zinc ions مع بعض.","screen_text":"From one solution of copper ions and zinc ions"},{"id":"s2l12","visual":"[CORE] CELL: the handle pulses with its 'cathode' tag on cue 'cathode'; a mixed coat of lettered Cu/Zn dots grows on its surface on cue 'بيترسبوا'; tag 'brass coat' at line end.","tts_text":"الـ handle هو الـ cathode، والاتنين بيترسبوا عليه في نفس اللحظة.","screen_text":"The handle is the cathode: both metals deposit on it together"},{"id":"s2l13","visual":"[CORE] FB split (E7, first-mentioned left): left a cell with lettered Cu dots only → plain copper coat, tag 'one metal: not an alloy' + YK.wrongMark on cue 'مش'; right the brass cell from s2l12.","tts_text":"لكن لو المحلول فيه copper ions بس، يطلع طلاء copper لوحده، مش alloy خالص.","screen_text":"Copper ions only: a copper coat, not an alloy"},{"id":"s2l14","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: Cu + Sn by electro-deposition; not in the book's example, the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: CELL with lettered Cu dots on cue 'copper' and lettered Sn dots on cue 'tin'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"طب محلول فيه copper ions و tin ions؟ إيه اللي هيترسب؟ وقّفوا وفكّروا.","screen_text":"Copper ions + tin ions: what coats the object?","pause_after_s":3},{"id":"s2l15","visual":"[CORE] CELL: a mixed coat of lettered Cu/Sn dots grows on the object on cue 'بيترسبوا'; answer 'Bronze (Cu + Sn) ✓' on cue 'bronze' (bronze = copper-tin alloy, book p.7, te-uses Cu: 'copper tin alloys are known as bronze').","tts_text":"الـ bronze، copper و tin مع بعض: الاتنين بيترسبوا في نفس الوقت.","screen_text":"Bronze (Cu + Sn), an alloy ✓ both deposit at the same time"},{"id":"s2l16","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Alloys: definition and preparation', line:'Preparation: by melting · by electro-deposition', pulse:[{word:'melting', at:YK.cue('s2l16','melting')}, {word:'electro-deposition', at:YK.cue('s2l16','electro-deposition')}]}).","tts_text":"الخلاصة: الـ alloy بنحضّره بالـ melting، أو بالـ electro-deposition كمان.","screen_text":"Preparation of alloys: by melting · by electro-deposition"},{"id":"s2l17","visual":"[CORE] SO-WHAT · FB: camera zooms into the brass bar to its atoms (LATTICE) on cue 'جوه'; a '?' over the atoms on cue 'فين'. Segment chip out; in the pause: camera move into the PART 3 card.","tts_text":"طب جوه الـ alloy… الذرات الجديدة دي بتقعد فين؟","screen_text":"Inside an alloy: where do the new atoms sit?","pause_after_s":2.5},{"id":"s3l1","style":"curious","visual":"PART 3/5 · alloy.interstitial · objective: Explain why steel is harder than pure iron. · [CORE] Segment card in s2l17's 2.5 s pause (camera move in, no fade): YK.partCard({num:3, of:5, title:'Interstitial alloys', objective:'Explain why steel is harder than pure iron', at: cueEnd(previous line)+0.1, collapse: YK.cue('s3l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Interstitial alloys', never cut) on line start, chip kept to the micro-recap. Line: FB split (E7, first-mentioned left): a pure iron bar bends on cue 'طري'; a steel bar stays straight on cue 'steel'; '?' between on cue 'منين'. RE-HOOK.","tts_text":"الحديد النقي طري، والـ steel ناشف جدًا… الفرق جاي منين؟","screen_text":"Pure iron is soft. Steel is hard. Why?"},{"id":"s3l2","visual":"PREREQ bond.metallic-bond [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · FB. Prereq YK.chip (link icon) 'Metallic bond'. Same model as lesson-bond.metallic-bond: LATTICE with charge '+' on cue 'ions' and sea:{count:60} electron dots on cue 'electrons'. Prereq chip out at line end.","tts_text":"فاكرين الـ metallic bond؟ ions موجبة في بحر من الـ electrons الحرة.","screen_text":"Metallic bond: metal ions in a sea of free electrons"},{"id":"s3l3","visual":"[CORE] FB LATTICE (5 rows × 9, all grey Fe; book fig 1-5 a) builds row by row on cue 'مترصّصة'; label 'crystal lattice' on cue 'crystal' (NEW TERM 1/3); caption tag 'Pure metal (fig 1-5 a)'.","tts_text":"الحديد النقي ذراته مترصّصة صفوف، وده الـ crystal lattice بتاعه.","screen_text":"Pure iron: a crystal lattice of atoms in compact close rows"},{"id":"s3l4","visual":"[CORE] FB: YK.hammer strikes from the left on cue 'خبطنا'; its impact drives slip 0 → 1 (top layers slide right on the gold slip plane) on cue 'بتتزحلق'; tag 'layers slip (fig 1-5 b)'.","tts_text":"لو خبطنا عليه بالشاكوش، طبقة ذرات بتتزحلق فوق التانية.","screen_text":"On hammering: a layer of atoms slips over the other layers"},{"id":"s3l5","visual":"[CORE] FB: the iron bar of s3l1 bends again on cue 'malleable'; label 'malleable' (same wording as the s1l2 recap).","tts_text":"عشان كده الحديد النقي malleable، وبيتشكل بسهولة.","screen_text":"Layers slip → pure iron is malleable"},{"id":"s3l6","visual":"[CORE] QUICK CHECK (mid-segment, ≥ 1 s pause, E1a; Part 3 > 120 s) · YK.predictCard({kind:'QUICK CHECK', q: screen_text}) in the text panel; stage: the slip plane glows; YK.thinkRing through the 1.5 s pause.","tts_text":"سؤال سريع: إيه اللي ممكن يوقّف الطبقات دي عن الزحلقة؟","screen_text":"Quick check: what could stop the layers from slipping?","pause_after_s":1.5},{"id":"s3l7","visual":"[CORE] FB LATTICE: gold carbon atoms (insert, scale 0.45) drop into the spaces between the rows on cue 'carbon'; label 'spaces' on cue 'spaces'.","tts_text":"ذرات صغيرة، زي الـ carbon، تدخل في الـ spaces بين ذرات الحديد.","screen_text":"Small atoms (e.g. carbon) in the spaces of the lattice"},{"id":"s3l8","visual":"[CORE] FB zoom on one space: a dashed circle 'space' and the gold C atom inside it, size compared on cue 'أصغر' (book fig 1-5 c caption).","tts_text":"والذرات دي أصغر من الـ spaces نفسها، فبتخش جوه بسهولة.","screen_text":"The introduced atoms are smaller than the spaces"},{"id":"s3l9","visual":"[CORE] FB: the hammer strikes again; LATTICE blocked:true (the layers try and spring back) on cue 'متعرفش'; tag 'hardness ↑' (gold) on cue 'hardness'. This is the mechanism shot (R3).","tts_text":"الذرات دي بتسد الطريق، فالطبقات متعرفش تتزحلق، والـ hardness بتزيد.","screen_text":"They prevent the movement of the layers → hardness ↑"},{"id":"s3l10","visual":"[CORE] TP DEFINITION CARD (E3a, the part's one card) YK.termCard({term:'Interstitial alloy', def:'An element with a small atomic size is introduced into the spaces of the crystal lattice of a pure metal.', keys:['small atomic size','spaces']}) on cue 'interstitial' (NEW TERM 2/3); 'spaces' gold on cue 'spaces'.","tts_text":"ده اسمه interstitial alloy: ذرات صغيرة في الـ spaces بتاعة الـ crystal lattice نفسه.","screen_text":"Interstitial alloy: small atoms in the spaces of the crystal lattice"},{"id":"s3l11","visual":"[CORE] FB: LATTICE grey + gold C atoms with the tag 'Steel (Fe + C)' on cue 'steel'; the c4 gold tag 'Why is steel harder than pure iron?' pulses.","tts_text":"والمثال بتاع الكتاب: الـ steel، carbon جوه الحديد.","screen_text":"Example: steel (iron + carbon)"},{"id":"s3l12","visual":"[CORE] FB (breaks the text-panel run; G40, alloy.interstitial misconception #1): LATTICE large; a ghost C atom shrinks into an Fe atom's place, small YK.mythLine 'C replaces Fe atoms' + ✕ on cue 'مكان' (< 2 s, smaller than the fix); then the C atom pops back into the space with YK.rightMark and tag 'it sits in the spaces' on cue 'بينهم'.","tts_text":"وخدوا بالكم: الـ carbon مش بياخد مكان ذرة حديد، ده بيقعد بينهم.","screen_text":"Carbon does not replace iron atoms ✗ it sits in the spaces"},{"id":"s3l13","visual":"[CORE] E2c (style-video-episode v6): the book's list of changed physical properties p.19, one item per line, ≥ 1 line apart, no definition card; items are known words (s1l2, s3l5). FB (breaks the text-panel run, s3l13–s3l17 are one full-bleed shot): the blocked LATTICE small at the top centre (y 160–520); header 'Also changes:' (Cairo 800 40, x 96, y 600); property tiles (YK.tag 40) build in two rows across the frame (row 1 y 700: hardness · malleability · ductility; row 2 y 820: melting point · electric conductivity · magnetic properties): 'hardness' (gold, already true) on cue 'hardness', 'malleability' on cue 'malleability'.","tts_text":"ومش الـ hardness بس اللي بتتغير… الـ malleability كمان،","screen_text":"Not only hardness: malleability changes"},{"id":"s3l14","visual":"[CORE] E2c tile 'ductility' on cue 'ductility'; a short wire draws out of the lattice block's right edge.","tts_text":"والـ ductility، يعني سحبه أسلاك،","screen_text":"ductility"},{"id":"s3l15","visual":"[CORE] E2c tile 'melting point' on cue 'melting'; a small thermometer glyph beside the tile.","tts_text":"والـ melting point بتاعه كمان،","screen_text":"melting point"},{"id":"s3l16","visual":"[CORE] E2c tile 'electric conductivity' (row 2) on cue 'electric'; a small current arrow runs through the lattice block.","tts_text":"والـ electric conductivity بتاعته،","screen_text":"electric conductivity"},{"id":"s3l17","visual":"[CORE] E2c tile 'magnetic properties' on cue 'magnetic'; a small YK.magnet beside the block. Book p.19 list complete; the tiles stay as the persistent anchor until s3l18.","tts_text":"والـ magnetic properties بتاعة المعدن.","screen_text":"magnetic properties"},{"id":"s3l18","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: nickel vs carbon; not asked in the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: an iron lattice space (dashed) with a gold C atom on cue 'carbon' and a green Ni atom (same size as Fe) on cue 'nickel', drawn to scale; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"طب أنهي ذرة تدخل في الـ spaces بتاعة الحديد: carbon ولا nickel؟ وقّفوا وفكّروا.","screen_text":"Which atom fits in iron's spaces: carbon or nickel?","pause_after_s":3},{"id":"s3l19","visual":"[CORE] FB: the C atom drops into the space with YK.rightMark on cue 'صغيرة'; the Ni atom (drawn to scale, about the size of an Fe atom) bumps the space and stays out on cue 'هيخش'; size brackets only, NO radius numbers here (the radius data are the Part 4 prerequisite recap, E2d: first use stays in s4l2).","tts_text":"الـ carbon، ذرته صغيرة. أما الـ nickel فقد ذرة الحديد تقريبًا، مش هيخش.","screen_text":"Carbon ✓ small atom · nickel: about iron's size, too big for the spaces"},{"id":"s3l20","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Interstitial alloys', line:'Small atoms in the spaces block the layers: steel is harder', pulse:[{word:'block', at:YK.cue('s3l20','بيسد')}, {word:'harder', at:YK.cue('s3l20','أصلب')}]}).","tts_text":"الخلاصة: الـ carbon بيسد الطبقات، فالـ steel أصلب من الحديد النقي.","screen_text":"Steel: small C atoms block the layers → harder than pure iron"},{"id":"s3l21","visual":"[CORE] SO-WHAT · FB: the green Ni atom from s3l19 hovers over the lattice on cue 'قد'; '?' on cue 'فين'. Segment chip out; m1 follows.","tts_text":"طب ذرة قد ذرة الحديد بالظبط… هتروح فين؟","screen_text":"A same-size atom: where does it go?","pause_after_s":1},{"id":"m1l1","visual":"[CORE] MID-EPISODE RECAP 1 (after Parts 1-3) · FB. YK.flow({rtl:false, layout:'row', area:{x:96,y:380,w:1728,h:320}, node:{size:40}}); header 'So far' (Cairo 800 40). Node 1 'Alloy' (sub 'two metals or more · metal + non-metal') lit on cue 'alloy'; sub-line pulses on cue 'non-metal'.","tts_text":"نلم اللي فات: الـ alloy اتنين metals أو أكتر، أو metal مع non-metal كمان.","screen_text":"Alloy: two metals or more, or a metal + a non-metal"},{"id":"m1l2","visual":"[CORE] Flow: arrow + node 2 'Preparation' (sub 'melting · electro-deposition', each lit on cues 'melting', 'electro-deposition').","tts_text":"وبنحضّره بالـ melting، أو بالـ electro-deposition من محلول واحد.","screen_text":"Prepared by melting or by electro-deposition"},{"id":"m1l3","visual":"[CORE] Flow: arrow + node 3 'Interstitial' (sub 'small atoms in the spaces → steel is harder') lit on cue 'interstitial'; sub-line 'spaces' pulses on cue 'spaces', 'steel is harder' on cue 'أصلب'. In the pause: camera move into the PART 4 card.","tts_text":"والـ interstitial: ذرات صغيرة في الـ spaces، فالـ steel أصلب.","screen_text":"Interstitial: small atoms in the spaces → steel is harder","pause_after_s":2.5},{"id":"s4l1","style":"curious","visual":"PART 4/5 · alloy.substitutional · objective: State the conditions of a substitutional alloy and give examples. · [CORE] Segment card in m1l3's 2.5 s pause (camera move in, no fade): YK.partCard({num:4, of:5, title:'Substitutional alloys', objective:'State the conditions of a substitutional alloy and give examples', at: cueEnd(previous line)+0.1, collapse: YK.cue('s4l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Substitutional alloys', never cut) on line start, chip kept to the micro-recap. Line: FB a stainless-steel spoon on cue 'stainless'; zoom into its LATTICE, teal Cr atoms hidden as '?' on cue 'chromium'. RE-HOOK.","tts_text":"في الـ stainless steel فيه chromium جوه الحديد… قاعد في الـ spaces برضه؟","screen_text":"Stainless steel: chromium inside iron. In the spaces?"},{"id":"s4l2","visual":"PREREQ te.atomic-radius [RECAP-PREREQ] (one line, ≤ 8 s; in-book concept of Unit 4, callback adding only what this part needs) · TP. Prereq YK.chip (link icon) 'Atomic radius: nearly constant'. RADIUS BAR (f) from the book table p.12 (for illustration): Cr 1.17 · Mn 1.17 · Fe 1.16 · Co 1.16 · Ni 1.15 · Cu 1.17 builds on cue 'radius'; a flat gold line through the bar tips on cue 'ثابت'. Same bar model as the te-physical-properties episode. Prereq chip out at line end.","tts_text":"فاكرين الـ atomic radius؟ من الـ chromium لحد الـ copper تقريبًا ثابت.","screen_text":"Atomic radius: nearly constant from Cr to Cu"},{"id":"s4l3","visual":"[CORE] FB: one teal Cr disc and one grey Fe disc side by side, same scale, values '1.17' / '1.16' on cue 'chromium'; an equal sign pulses on cue 'قد'.","tts_text":"يعني ذرة الـ chromium تقريبًا قد ذرة الحديد بالظبط.","screen_text":"Cr 1.17 · Fe 1.16: about the same size"},{"id":"s4l4","visual":"[CORE] FB LATTICE: the Cr atom tries a space (doesn't fit) on cue 'spaces', then swaps into an Fe atom's place (substitute) on cue 'مكان'; the lattice keeps its shape.","tts_text":"فبدل ما تدخل في الـ spaces، بتاخد مكان ذرة حديد.","screen_text":"So a Cr atom takes the place of an Fe atom"},{"id":"s4l5","visual":"[CORE] FB LATTICE wide: rows and spacing unchanged; the few teal Cr atoms pulse on cue 'ذرات' (approved lesson-alloy.substitutional wording).","tts_text":"والـ lattice نفسه شكله زي ما هو، بس شوية ذرات اتغيرت.","screen_text":"The lattice keeps its shape: only some atoms are different"},{"id":"s4l6","visual":"[CORE] TP DEFINITION CARD (E3a, the part's one card) YK.termCard({term:'Substitutional alloy', def:'Some of the atoms of the pure metal are replaced by atoms of another metal which has the same atomic radius, crystal lattice and chemical properties.', keys:['replaced']}) first sentence on cue 'substitutional' (NEW TERM 1/3); stage: LATTICE with several teal Cr atoms in Fe places.","tts_text":"ده الـ substitutional alloy: ذرات من معدن تاني بتاخد مكان ذرات المعدن الأصلي.","screen_text":"Substitutional alloy: some atoms of the pure metal are replaced by atoms of another metal"},{"id":"s4l7","visual":"[CORE] TP: the card's conditions build one per line (book list p.20): '1. the same atomic radius' on cue 'radius'; stage: equal-size discs pulse.","tts_text":"بشرط إن المعدن التاني ليه نفس الـ atomic radius،","screen_text":"Conditions: 1. the same atomic radius"},{"id":"s4l8","visual":"[CORE] FB split (E7, breaks the text-panel run; first-mentioned left, identical scale): left a small Fe LATTICE (grey), right a Cr LATTICE (teal) with the same rows and spacing; panel titles 'Fe' / 'Cr'; condition '2. the same crystal lattice' added to the text-panel list (returns on s4l9) on cue 'crystal'.","tts_text":"ونفس شكل الـ crystal lattice بتاعه،","screen_text":"2. the same crystal lattice"},{"id":"s4l9","visual":"[CORE] TP condition '3. the same chemical properties' on cue 'chemical'; stage: both discs get a matching 'chemical properties' tag.","tts_text":"ونفس الـ chemical properties كمان.","screen_text":"3. the same chemical properties"},{"id":"s4l10","visual":"[CORE] E2c (style-video-episode v6): the book's three examples p.20 build as ONE list, one item per line, no definition card per item (counts as one new term, 2/3). TP list 'Examples (p.20)' item '1) Ferrochrome (Fe–Cr)' on cue 'ferrochrome'; tag 'in stainless steel' on cue 'stainless'; stage: the s4l1 spoon returns small.","tts_text":"أول مثال: الـ ferrochrome، اللي في الـ stainless steel بتاعنا.","screen_text":"1) Ferrochrome (Fe–Cr): in stainless steel"},{"id":"s4l11","visual":"[CORE] E2c item '2) Copper–gold alloy' on cue 'copper'; stage: LATTICE copper-brown atoms with a few gold atoms in their places on cue 'gold'.","tts_text":"تاني مثال: سبيكة الـ copper والـ gold مع بعض.","screen_text":"2) Copper–gold alloy"},{"id":"s4l12","visual":"[CORE] FB (breaks the text-panel run): LATTICE grey Fe full-bleed; the green Ni atom from s3l19 finally lands in an Fe place on cue 'الحديد' (substitute); E2c item '3) Ferronickel (Fe–Ni)' as a tag on the lattice on cue 'ferronickel' (added to the text-panel list when it returns on s4l13).","tts_text":"وتالت مثال: الـ ferronickel، nickel مع الحديد.","screen_text":"3) Ferronickel (Fe–Ni)"},{"id":"s4l13","visual":"[CORE] TP callback: the s4l2 RADIUS BAR returns small, the flat gold line pulses on cue 'ثبات'; book quote 'explains using them in making alloys' (p.12) on cue 'بيفسر'.","tts_text":"وده اللي الكتاب قاله: ثبات الـ radius بيفسر ليه بنعمل منهم alloys كتير.","screen_text":"Nearly constant radius: explains their use in making alloys (p.12)"},{"id":"s4l14","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: cobalt; not in the episode, the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: Co disc (blue) and Fe disc, both '1.16' (book table p.12) on cue 'cobalt'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"طب الـ cobalt قد الحديد بالظبط. الحجم ده لوحده كفاية؟ وقّفوا وفكّروا.","screen_text":"Cobalt (1.16) and iron (1.16): is the same radius enough?","pause_after_s":3},{"id":"s4l15","visual":"[CORE] TP: the three conditions return; '1. radius' ticks, '2.' and '3.' pulse gold on cues 'crystal', 'chemical'; answer 'Not alone' + YK.wrongMark on cue 'لوحده'. Refutes alloy.substitutional misconception #1 (any two metals can form a substitutional alloy). No claim about the real Fe–Co alloy.","tts_text":"لأ، مش لوحده: لازم الـ crystal lattice والـ chemical properties كمان.","screen_text":"Not alone ✗ the crystal lattice and chemical properties must match too"},{"id":"s4l16","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Substitutional alloys', line:'Same radius, crystal lattice and chemical properties: atoms take each other\\'s places', pulse:[{word:'places', at:YK.cue('s4l16','أماكن')}]}) over a dimmed substitutional LATTICE (teal Cr in Fe places). One shot only (the interstitial vs substitutional split comes in s5l15–s5l16 and z3–z4).","tts_text":"الخلاصة: في الـ substitutional، ذرات قد بعض بتاخد أماكن بعض.","screen_text":"Substitutional: same-size atoms take each other's places"},{"id":"s4l17","visual":"[CORE] SO-WHAT · FB: two atoms (grey Fe, gold C) snap together with a bond line on cue 'اتحدت'. Segment chip out; in the pause: camera move into the PART 5 card.","tts_text":"طب ولو الذرات اتحدت كيميائيًا مع بعض؟ ده نوع تالت.","screen_text":"And if the atoms combine chemically?","pause_after_s":2.5},{"id":"s5l1","style":"curious","visual":"PART 5/5 · alloy.intermetallic · objective: Explain why intermetallic alloys are chemical compounds. · [CORE] Segment card in s4l17's 2.5 s pause (camera move in, no fade): YK.partCard({num:5, of:5, title:'Intermetallic alloys', objective:'Explain why intermetallic alloys are chemical compounds', at: cueEnd(previous line)+0.1, collapse: YK.cue('s5l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Intermetallic alloys', never cut) on line start, chip kept to the micro-recap. Line: FB LATTICE compound:{ratio:[3,1], formula:'Fe3C'} (ordered pattern, pink '#FF7AB6' C positions) on cue 'carbon'; formula tag 'Fe₃C' on cue 'formula'. RE-HOOK.","tts_text":"حديد و carbon تاني… بس المرة دي ليهم formula ثابتة. إزاي؟","screen_text":"Iron + carbon again: now with a fixed formula, Fe₃C"},{"id":"s5l2","visual":"[CORE] TP DEFINITION CARD (E3a, the part's one card) YK.termCard({term:'Intermetallic alloy', def:'The elements forming the alloy combine with each other chemically to form a chemical compound.', keys:['combine chemically','chemical compound']}) on cue 'intermetallic' (NEW TERM 1/3); stage: bond lines draw between the Fe₃C units on cue 'بتتحد'.","tts_text":"ده الـ intermetallic alloy: العناصر بتتحد كيميائيًا، وتعمل chemical compound جديد.","screen_text":"Intermetallic alloy: the elements combine chemically to form a chemical compound"},{"id":"s5l3","visual":"[CORE] FB three mini lattices LTR in book order (interstitial, substitutional, intermetallic), identical scale; the first two get a 'no compound' tag, the third 'compound' (gold) on cue 'الوحيد'. Refutes alloy.definition-preparation misconception #2 (every alloy is a chemical compound) and alloy.intermetallic misconception #1 (physical mixtures).","tts_text":"فمش كل alloy يبقى compound… ده النوع الوحيد فيهم اللي فيه اتحاد كيميائي.","screen_text":"Not every alloy is a compound: of the three types, only this one"},{"id":"s5l4","visual":"[CORE] E2c (style-video-episode v6): the book's three examples p.20 build as ONE list, one item per line, no definition card per item (counts as one new term, 2/3). TP list 'Examples (p.20)' item '1) Duralumin: Al–Ni · Al–Cu' on cue 'duralumin'; 'Al–Ni' on cue 'nickel', 'Al–Cu' on cue 'copper'.","tts_text":"أول مثال: الـ duralumin، aluminum مع nickel، أو aluminum مع copper كمان.","screen_text":"1) Duralumin: aluminum–nickel · aluminum–copper"},{"id":"s5l5","visual":"[CORE] E2c item '2) Lead–gold alloy' on cue 'lead'; formula 'Au₂Pb' (YK.formula 56, '2' gold) on cue 'اتنين'.","tts_text":"تاني مثال: سبيكة الـ lead والـ gold، اتنين gold لكل lead واحد.","screen_text":"2) Lead–gold alloy: Au₂Pb"},{"id":"s5l6","visual":"[CORE] FB (breaks the text-panel run): the s5l1 Fe₃C compound LATTICE returns full-bleed; E2c item '3) Cementite: Fe₃C' as the formula tag on cue 'cementite'; three Fe and one C of one formula unit ringed, '3' gold on cue 'تلاتة' (added to the text-panel list when it returns on s5l7).","tts_text":"وتالت مثال: الـ cementite، تلاتة iron لكل carbon واحد.","screen_text":"3) Cementite: Fe₃C"},{"id":"s5l7","visual":"PREREQ chem.valency-formulas [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Valency and writing chemical formulas'. SWAP model (e), same model as video-short-chem.valency-formulas: two blank tiles with valency numbers above, the numbers arc across (crossing arrows) on cue 'بنبدّل', subscripts land in dashed slots (never 'X_ Y_' strings) on cue 'formula'. Prereq chip out at line end.","tts_text":"فاكرين الـ valency؟ بنبدّل أرقام الـ valency عشان نكتب أي formula صح.","screen_text":"Valency: swap the valencies to write a formula"},{"id":"s5l8","visual":"[CORE] TP: book line 'Its chemical formula disobeys the valence law' on cue 'بتخالف'; 'valence law' gold on cue 'valence' (NEW TERM 3/3).","tts_text":"والكتاب بيقول: الـ formula بتاعته بتخالف الـ valence law، تعالوا نجرب.","screen_text":"Its chemical formula disobeys the valence law"},{"id":"s5l9","visual":"[CORE] TP worked example panel (E3a, ≤ 4 notation rows) header 'Test Fe₃C' on cue 'cementite'; tags 'metal' / 'non-metal' under Fe / C on cues 'metal', 'non-metal' (the swap pairs a metal with a non-metal; two metals as in Au₂Pb cannot be swapped, approved lesson-alloy.intermetallic).","tts_text":"نجرب على الـ cementite: هو metal مع non-metal، فينفع نبدّل.","screen_text":"Swap test on Fe₃C: a metal + a non-metal"},{"id":"s5l10","visual":"[CORE] FB close-up (breaks the text-panel run; worked example, memory pattern): SWAP model large at the centre (tiles 'Fe' / 'C', JetBrains Mono ≥ 72): 'Fe (2)' on cue 'iron', 'C (4)' on cue 'carbon', the numbers arc across → 'Fe₄C₂' on cue 'نبدّل', '÷2 → Fe₂C' on cue 'ونختصر'; formula strip y 900 keeps 'Test Fe₃C' as the target.","tts_text":"لو الـ iron اتنين، والـ carbon أربعة: نبدّل ونختصر، اتنين iron لكل carbon واحد.","screen_text":"Iron (2) + carbon (4) → Fe₄C₂ → Fe₂C"},{"id":"s5l11","visual":"[CORE] QUICK CHECK (mid-segment, ≥ 1 s pause, E1a; worked → faded) · SWAP row 2 skeleton: 'Fe (3)' on cue 'تلاتة' with the tile C (4) beside it; '→ ?' on cue 'جربوا'; YK.thinkRing through the 1.5 s pause.","tts_text":"ولو الـ iron تلاتة؟ جربوا انتوا الأول بسرعة.","screen_text":"Quick check: iron (3) + carbon (4) → ?","pause_after_s":1.5},{"id":"s5l12","visual":"[CORE] SWAP row 2 fills: '→ Fe₄C₃' on cue 'أربعة'; a coral ≠ 'Fe₃C' on cue 'مش'.","tts_text":"أربعة iron وتلاتة carbon، برضه مش هي.","screen_text":"Iron (3) + carbon (4) → Fe₄C₃"},{"id":"s5l13","visual":"[CORE] FB: the real 'Fe₃C' large; both swap results slide beside it with ≠ on cue 'طلعت'; stamp 'disobeys the valence law' on cue 'valence'.","tts_text":"ولا واحدة طلعت تلاتة لواحد… يعني بتخالف الـ valence law فعلًا.","screen_text":"Neither gives Fe₃C → it disobeys the valence law"},{"id":"s5l14","visual":"[CORE] FB YK.periodicTable (maxH ≤ 860, dimmed): the columns of Al and Cu (duralumin, s5l4) light in two different colours on cue 'group'; book p.20 statement only, no claim that same-group metals cannot form one.","tts_text":"وكمان الـ metals اللي فيه مش من نفس الـ group في الجدول.","screen_text":"Its metals are not in the same group"},{"id":"s5l15","visual":"[CORE] FB split (E7, first-mentioned left, identical scale): left LATTICE grey Fe + gold C in the spaces, title 'Steel: interstitial' on cue 'interstitial'. Refutes alloy.interstitial misconception #3 / alloy.intermetallic misconception #2 (steel and cementite are the same type).","tts_text":"الـ steel نوعه interstitial: الـ carbon قاعد في الـ spaces بس.","screen_text":"Steel: interstitial (C in the spaces)"},{"id":"s5l16","visual":"[CORE] Split right panel: Fe₃C ordered LATTICE with bond lines, title 'Cementite: intermetallic' on cue 'intermetallic'; bonds pulse on cue 'متحدين'. Difference in gold.","tts_text":"إنما الـ cementite نوعه intermetallic: الـ iron والـ carbon متحدين.","screen_text":"Fe₃C (cementite): intermetallic, a chemical compound"},{"id":"s5l17","visual":"[CORE] PAUSE-AND-PREDICT part 1 (NEW case: a made-up metal of valency 1 with carbon; the unit's lesson uses valency 2 → X₃C, the question valency 3 → Q₄C). TP: tile 'M (1)' with tag 'made-up' on cue 'metal'.","tts_text":"طب metal افتراضي، الـ valency بتاعه واحد بس،","screen_text":"Metal M (made-up): valency 1 only"},{"id":"s5l18","visual":"[CORE] PAUSE-AND-PREDICT part 2 · question in the text panel; stage: tile 'C (4)' on cue 'carbon', the found formula 'M₂C' on cue 'اتنين'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"ومع الـ carbon ليه formula ثابتة: اتنين metal لكل carbon. أنهي نوع؟ وقّفوا وفكّروا.","screen_text":"With carbon (4) it forms M₂C. Which type of alloy?","pause_after_s":3},{"id":"s5l19","visual":"[CORE] SWAP row: 'M (1) + C (4) → M₄C' on cue 'أربعة'; '≠ M₂C' on cue 'مش'; answer 'Intermetallic ✓' + YK.rightMark on cue 'intermetallic'.","tts_text":"الـ valence law بتدّي أربعة لواحد، مش اتنين… فهو intermetallic أكيد.","screen_text":"Valence law: M₄C, not M₂C → intermetallic ✓"},{"id":"s5l20","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Intermetallic alloys', line:'A chemical compound: its formula disobeys the valence law', formula:'Fe₃C · Au₂Pb', pulse:[{word:'compound', at:YK.cue('s5l20','compound')}, {word:'valence', at:YK.cue('s5l20','valence')}]}).","tts_text":"الخلاصة: الـ intermetallic هو chemical compound، والـ formula بتاعته بتكسر الـ valence law كده.","screen_text":"Intermetallic: a chemical compound; its formula disobeys the valence law"},{"id":"s5l21","visual":"[CORE] SO-WHAT · FB: the three type lattices shrink into a row at the bottom on cue 'نلم'. Segment chip out.","tts_text":"يلا نلم الحلقة كلها في سلسلة واحدة.","screen_text":"Now the whole unit in one chain","pause_after_s":1},{"id":"z1","visual":"[CORE] CLOSING SUMMARY · FB. YK.flow({rtl:false}) LTR in book order, nodes ≥ 32 px: node 1 'Alloy' (sub 'two metals or more · metal + non-metal') on cue 'alloy'.","tts_text":"الـ alloy: اتنين metals أو أكتر، أو metal مع non-metal كمان.","screen_text":"Alloy: two metals or more, or a metal + a non-metal"},{"id":"z2","visual":"[CORE] FB flow: arrow + node 2 'Preparation' (sub 'melting · electro-deposition') on cues 'melting', 'electro-deposition'.","tts_text":"وبنحضّره بالـ melting، أو بالـ electro-deposition من محلول واحد.","screen_text":"Prepared by melting or by electro-deposition"},{"id":"z3","visual":"[CORE] FB flow: node 3 splits into three branches (types, book order); branch 1 'Interstitial' with mini LATTICE (gold C in spaces) on cue 'interstitial'.","tts_text":"والـ interstitial: ذرات صغيرة زي الـ carbon في الـ spaces بين الذرات.","screen_text":"Interstitial: small atoms in the spaces"},{"id":"z4","visual":"[CORE] FB flow branch 2 'Substitutional' with mini LATTICE (teal Cr in places) on cue 'substitutional'.","tts_text":"والـ substitutional: ذرات قد بعض بتبدّل أماكن بعض.","screen_text":"Substitutional: same-size atoms take each other's places"},{"id":"z5","visual":"[CORE] FB flow branch 3 'Intermetallic' with mini Fe₃C LATTICE on cue 'intermetallic'; sub 'disobeys the valence law' on cue 'valence'.","tts_text":"والـ intermetallic: اتحاد كيميائي، و formula بتخالف الـ valence law كمان.","screen_text":"Intermetallic: a chemical compound (formula disobeys the valence law)"},{"id":"z6","visual":"[CORE] BIG QUESTION ANSWERED · FB: the cold-open gold tag returns centre; the hammer hits the steel LATTICE, blocked:true, on cue 'بتمنع'; the tag gets ✓ on cue 'أصلب'.","tts_text":"وإجابة سؤالنا: الـ steel أصلب، عشان ذرات الـ carbon بتمنع الطبقات تتزحلق.","screen_text":"Why is steel harder than pure iron? ✓ small C atoms block the layers from slipping"},{"id":"z7","visual":"[CORE] RECALL 1/3 (Part 2; NEW case: Ni + Cr from one solution) · YK.predictCard({kind:'RECALL 1 OF 3', q: screen_text}) in the text panel; stage: CELL with lettered Ni dots on cue 'nickel' and lettered Cr dots on cue 'chromium'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"محلول فيه nickel ions و chromium ions، بيترسبوا على حتة. الطريقة إيه؟ وقّفوا وفكّروا.","screen_text":"Nickel ions and chromium ions deposit together on a part. Which method?","pause_after_s":3},{"id":"z8","visual":"[CORE] FB: the part gets a mixed coat of lettered Ni/Cr dots; answer 'Electro-deposition' + YK.rightMark on cue 'electro-deposition'; tag 'cathode' on the part on cue 'cathode'.","tts_text":"الإجابة: الـ electro-deposition، والحتة نفسها هي الـ cathode هنا.","screen_text":"Electro-deposition ✓ the part is the cathode"},{"id":"z9","visual":"[CORE] RECALL 2/3 (Part 4; book Evaluation Q1.8 p.25 wording) · YK.predictCard({kind:'RECALL 2 OF 3', q: screen_text}) in the text panel; stage: teal Cr and grey Fe discs; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"سؤال الكتاب: الـ chromium مع الحديد بيعملوا أنهي نوع alloy؟ وقّفوا وفكّروا.","screen_text":"Chromium and iron form … alloy.","pause_after_s":3},{"id":"z10","visual":"[CORE] FB: the Cr disc swaps into an Fe place in a LATTICE on cue 'substitutional' + YK.rightMark; radii '1.17 ≈ 1.16' on cue 'قد'.","tts_text":"الإجابة: substitutional، لأن ذراتهم قد بعض تقريبًا.","screen_text":"Substitutional ✓ Cr 1.17 ≈ Fe 1.16"},{"id":"z11","visual":"[CORE] RECALL 3/3 (Part 5; book Evaluation Q1.7 p.25 wording) · YK.predictCard({kind:'RECALL 3 OF 3', q: screen_text}) in the text panel; stage: three mini lattices, unlabelled; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"وآخر سؤال: النوع اللي عناصره متحدة كيميائيًا اسمه إيه؟ وقّفوا وفكّروا.","screen_text":"In which type of alloy are the elements bound together chemically?","pause_after_s":3},{"id":"z12","visual":"[CORE] FB: the Fe₃C mini lattice lights + YK.rightMark on cue 'intermetallic'; tag 'cementite Fe₃C' on cue 'cementite'.","tts_text":"الإجابة: الـ intermetallic، زي الـ cementite مثلًا.","screen_text":"Intermetallic ✓ e.g. cementite Fe₃C"},{"id":"z13","visual":"[TRIM-IF-OVER 15:00] TEASER (labelled last line only) · FB; label 'Next episode:' (Cairo 800 40, textDim) + 'Properties of iron' (Cairo 1000 64) on cue 'properties'. No subscribe. 0.8 s tail.","tts_text":"الحلقة الجاية: الـ properties بتاعة الحديد نفسه.","screen_text":"Next episode: Properties of iron"}],"logline":"Pure iron is relatively soft, so why is steel harder? Five parts in the book's order (pp.19-20): what an alloy is (two metals or more, or a metal and a non-metal such as carbon), the two ways to prepare one (melting; electro-deposition, brass on iron handles), interstitial alloys (small carbon atoms in the spaces block the layers: steel), substitutional alloys (same radius, crystal lattice and chemical properties: ferrochrome, copper-gold, ferronickel) and intermetallic alloys (a chemical compound whose formula disobeys the valence law: duralumin, Au₂Pb, cementite Fe₃C).","concept_ids":["alloy.definition-preparation","alloy.interstitial","alloy.substitutional","alloy.intermetallic"]},"layer":null,"layer_fallback":false,"images":{"cover_9x16":"https://cdn.yaani.ai/files/8f8a13a5ca2ec05c93ae8304e5e787579e599a0d9c2c715798361c446d6fc2e1.jpg","hero_21x9":"https://cdn.yaani.ai/files/fbda5e5b9d46c7d4fc70a584925ed287bc0a9312e14bcaf3e9f23f78b4d3eb11.jpg","hero_4x5":"https://cdn.yaani.ai/files/3e98ec9edcbce0fd48d63167bcc03141bb6d045708ab40f415b9600dfc20a9af.jpg","og":"https://cdn.yaani.ai/files/fa193308ea8d350c83f1bf91f6fc7d9cb2e0400f1d3572c40d25b19b4a71913d.jpg","poster":"https://cdn.yaani.ai/files/badc1045b60a5ee568f2d12b58a1e7cc69921211e631b93896d07ed77298c575.jpg","thumbnail":"https://cdn.yaani.ai/files/192d210c66aaa5a243ae069a26bd4813df3fe2fb197c1abb719a9a36260d6eba.jpg"},"thumbnail_variant":"b","files":[{"role":"captions","key":"ar-EG","url":"https://cdn.yaani.ai/files/2090247e05ef9f95f2bca0e5c2b82b87973a8f9136759a58344b0ee48e564604.vtt","mime":"text/vtt","size":13725},{"role":"chapters","key":"","url":"https://cdn.yaani.ai/files/c1d14accad6e06c0ce8fd998ed45ac663ec65dc547f3707e752cb9c71de5dc08.vtt","mime":"text/vtt","size":381},{"role":"cover_9x16","key":"","url":"https://cdn.yaani.ai/files/8f8a13a5ca2ec05c93ae8304e5e787579e599a0d9c2c715798361c446d6fc2e1.jpg","mime":"image/jpeg","size":82876},{"role":"cover_9x16","key":"a/1080x1920.avif","url":"https://cdn.yaani.ai/files/34456c4cce54c71c896bcb23774a8f062c5fa0bae29766cd2eb3873f8eceadc9.avif","mime":"image/avif","size":15178},{"role":"cover_9x16","key":"a/1080x1920.jpg","url":"https://cdn.yaani.ai/files/303ebeac9011456cf0b83a345019e6103f3af25240355fee72914d5b14fa99fd.jpg","mime":"image/jpeg","size":108522},{"role":"cover_9x16","key":"a/1080x1920.png","url":"https://cdn.yaani.ai/files/6dfe024b86c0504d7850bab2f82d7c59e3dc071f1f0fb8fe39b3f7776f3f4a8e.png","mime":"image/png","size":383153},{"role":"cover_9x16","key":"a/1080x1920.webp","url":"https://cdn.yaani.ai/files/f3334f9efcd14857f73a1d1d41c11f8fad0f5e007404c83802591b81791e35cd.webp","mime":"image/webp","size":30790},{"role":"cover_9x16","key":"a/540x960.avif","url":"https://cdn.yaani.ai/files/cc3a261e4a3ff46cc610f499ab4260d1812a84775395f94211d48b0458894fc6.avif","mime":"image/avif","size":7797},{"role":"cover_9x16","key":"a/540x960.jpg","url":"https://cdn.yaani.ai/files/eae4e2e2476645f90d4a433c19dedcf889e67de131c1f58d15d167fac8a3e0b0.jpg","mime":"image/jpeg","size":44857},{"role":"cover_9x16","key":"a/540x960.webp","url":"https://cdn.yaani.ai/files/993468ded95f85efe851c893c2e8d0ed7e3696c1a1ae7cd75bb1ed08e29aac6a.webp","mime":"image/webp","size":13918},{"role":"cover_9x16","key":"b/1080x1920.avif","url":"https://cdn.yaani.ai/files/5153148398aabdb92c3bba3bdc9b33c8522ee6740c6fc40b1e08ee6dbd14a9ba.avif","mime":"image/avif","size":11489},{"role":"cover_9x16","key":"b/1080x1920.jpg","url":"https://cdn.yaani.ai/files/8f8a13a5ca2ec05c93ae8304e5e787579e599a0d9c2c715798361c446d6fc2e1.jpg","mime":"image/jpeg","size":82876},{"role":"cover_9x16","key":"b/1080x1920.png","url":"https://cdn.yaani.ai/files/a572f6a87c8f014ed8976cd6d827566c40da13657a104ec1b8488ef2ca7a0be8.png","mime":"image/png","size":85956},{"role":"cover_9x16","key":"b/1080x1920.webp","url":"https://cdn.yaani.ai/files/2bd80964abd83caa32ae51d37174c031a0977d7910c222d61b8a08596f550ec5.webp","mime":"image/webp","size":18886},{"role":"cover_9x16","key":"b/540x960.avif","url":"https://cdn.yaani.ai/files/4a58e2d918dca33130899c9704c8d59b91c6ad6ea64ffde2a4dd89a69b8a068e.avif","mime":"image/avif","size":6366},{"role":"cover_9x16","key":"b/540x960.jpg","url":"https://cdn.yaani.ai/files/64438424f1cae3a38e94a8e33825f65eb1a9a194d198ed5daa0f2861eb7962b9.jpg","mime":"image/jpeg","size":36049},{"role":"cover_9x16","key":"b/540x960.webp","url":"https://cdn.yaani.ai/files/143dd86422879e2bee7624cac519d7a585f86b0976fa8253c61f4e41a5914448.webp","mime":"image/webp","size":9536},{"role":"hero_21x9","key":"","url":"https://cdn.yaani.ai/files/fbda5e5b9d46c7d4fc70a584925ed287bc0a9312e14bcaf3e9f23f78b4d3eb11.jpg","mime":"image/jpeg","size":98542},{"role":"hero_21x9","key":"a/1680x720.avif","url":"https://cdn.yaani.ai/files/d850390dc40ccc4faf3d6ff1377764f7adf0bb43a8eda13d0f079a65e3767843.avif","mime":"image/avif","size":11288},{"role":"hero_21x9","key":"a/1680x720.jpg","url":"https://cdn.yaani.ai/files/b4066fdc08ed8fa9e7fce143df051bae1cd5c91c96709e8353c2450fa6aafba3.jpg","mime":"image/jpeg","size":72267},{"role":"hero_21x9","key":"a/1680x720.webp","url":"https://cdn.yaani.ai/files/28c713eac980078e7c28edc73c419c89f8ef906d1251de7588a39f70808fce22.webp","mime":"image/webp","size":21018},{"role":"hero_21x9","key":"a/2520x1080.avif","url":"https://cdn.yaani.ai/files/a5f2a4fd30436504233d46e1dabbbe94042d18788ac35844480174c38b2f9da5.avif","mime":"image/avif","size":16638},{"role":"hero_21x9","key":"a/2520x1080.jpg","url":"https://cdn.yaani.ai/files/5c8636faa25a131205fb6b06e4b5253ae80e8ebb735a5c672b4660fc0ff8b679.jpg","mime":"image/jpeg","size":124199},{"rol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النقي طري نسبيًا وملوش أهمية في\nالصناعة لوحده\nأمّال قضبان السكة الحديد اللي شايلة القطر\nمعمولة من إيه\nمش حديد نقي دي ferromanganese alloy أصلب\nمن الـ steel كمان\nطب ليه الـ steel نفسه أصلب من الحديد النقي\nالحلقة دي عن الـ alloys وأنواعها التلاتة\nهي الـ alloy لازم تبقى metals بس\nفاكرين الـ metals بتلمع وهي malleable و\nductile والـ non-metals غالبًا لأ\nالـ alloys عادة بتتكون من اتنين metals أو\nأكتر\nزي الـ ferrochromium وكلمة ferro يعني حديد\nوالـ ferromanganese اللي في قضبان السكة\nالحديد\nوالـ ferrovanadium حديد مع vanadium جواه\nوالـ ferronickel حديد مع nickel كلهم\nmetals مع بعض\nوليه نخلط أصلًا عشان نغيّر خواص الـ metal\nزي الـ hardness بتاعته\nناس كتير فاكرة إن الـ alloy لازم يبقى\nmetals بس\nلأ الـ steel فيه carbon وهو non-metal\nوبرضه alloy عادي\nطب الـ gold عيار أربعة وعشرين يعني صافي ده\nalloy وقّفوا وفكّروا\nلأ ده metal واحد بس والـ alloy محتاج اتنين\nأو أكتر\nالخلاصة الـ alloy اتنين metals أو أكتر أو\nmetal مع non-metal كمان\nطب إزاي نخلط الحاجات دي ببعض أصلًا\nاتنين metals صلبين هيتخلطوا إزاي وهما حتت\nناشفة كده\nأول طريقة الـ melting ندوّب الـ metals مع\nبعض\nوبعدين نسيبهم يبردوا بالراحة بالتدريج لحد\nما يجمدوا\nوهما سايلين الذرات بتتخلط كويس قوي ببعضها\nسؤال سريع zinc و copper دايبين مع بعض\nوبردوا alloy ولا لأ\nأيوه alloy واسمه brass وهنقابله تاني\nدلوقتي\nفاكرين الـ electroplating بنعدّي electric\ncurrent في محلول فيه metal ions ذايبة\nوالـ ions بتاخد electrons عند الـ cathode\nمكان الـ reduction وهو الحاجة اللي بنطليها\nتاني طريقة الـ electro-deposition نرسّب\nاتنين metals أو أكتر في نفس الوقت\nزي ما بنطلي مقابض الحديد بالـ brass يعني\ncopper و zinc مع بعض\nمن محلول واحد فيه copper ions و zinc ions\nمع بعض\nالـ handle هو الـ cathode والاتنين\nبيترسبوا عليه في نفس اللحظة\nلكن لو المحلول فيه copper ions بس يطلع\nطلاء copper لوحده مش alloy خالص\nطب محلول فيه copper ions و tin ions إيه\nاللي هيترسب وقّفوا وفكّروا\nالـ bronze copper و tin مع بعض الاتنين\nبيترسبوا في نفس الوقت\nالخلاصة الـ alloy بنحضّره بالـ melting أو\nبالـ electro-deposition كمان\nطب جوه الـ alloy الذرات الجديدة دي بتقعد\nفين\nالحديد النقي طري والـ steel ناشف جدًا\nالفرق جاي منين\nفاكرين الـ metallic bond ions موجبة في بحر\nمن الـ electrons الحرة\nالحديد النقي ذراته مترصّصة صفوف وده الـ\ncrystal lattice بتاعه\nلو خبطنا عليه بالشاكوش طبقة ذرات بتتزحلق\nفوق التانية\nعشان كده الحديد النقي malleable وبيتشكل\nبسهولة\nسؤال سريع إيه اللي ممكن يوقّف الطبقات دي\nعن الزحلقة\nذرات صغيرة زي الـ carbon تدخل في الـ\nspaces بين ذرات الحديد\nوالذرات دي أصغر من الـ spaces نفسها فبتخش\nجوه بسهولة\nالذرات دي بتسد الطريق فالطبقات متعرفش\nتتزحلق والـ hardness بتزيد\nده اسمه interstitial alloy ذرات صغيرة في\nالـ spaces بتاعة الـ crystal lattice نفسه\nوالمثال بتاع الكتاب الـ steel carbon جوه\nالحديد\nوخدوا بالكم الـ carbon مش بياخد مكان ذرة\nحديد ده بيقعد بينهم\nومش الـ hardness بس اللي بتتغير الـ\nmalleability كمان\nوالـ ductility يعني سحبه أسلاك\nوالـ melting point بتاعه كمان\nوالـ electric conductivity بتاعته\nوالـ magnetic properties بتاعة المعدن\nطب أنهي ذرة تدخل في الـ spaces بتاعة\nالحديد carbon ولا nickel وقّفوا وفكّروا\nالـ carbon ذرته صغيرة أما الـ nickel فقد\nذرة الحديد تقريبًا مش هيخش\nالخلاصة الـ carbon بيسد الطبقات فالـ steel\nأصلب من الحديد النقي\nطب ذرة قد ذرة الحديد بالظبط هتروح فين\nنلم اللي فات الـ alloy اتنين metals أو\nأكتر أو metal مع non-metal كمان\nوبنحضّره بالـ melting أو بالـ\nelectro-deposition من محلول واحد\nوالـ interstitial ذرات صغيرة في الـ spaces\nفالـ steel أصلب\nفي الـ stainless steel فيه chromium جوه\nالحديد قاعد في الـ spaces برضه\nفاكرين الـ atomic radius من الـ chromium\nلحد الـ copper تقريبًا ثابت\nيعني ذرة الـ chromium تقريبًا قد ذرة\nالحديد بالظبط\nفبدل ما تدخل في الـ spaces بتاخد مكان ذرة\nحديد\nوالـ lattice نفسه شكله زي ما هو بس شوية\nذرات اتغيرت\nده الـ substitutional alloy ذرات من معدن\nتاني بتاخد مكان ذرات المعدن الأصلي\nبشرط إن المعدن التاني ليه نفس الـ atomic\nradius\nونفس شكل الـ crystal lattice بتاعه\nونفس الـ chemical properties كمان\nأول مثال الـ ferrochrome اللي في الـ\nstainless steel بتاعنا\nتاني مثال سبيكة الـ copper والـ gold مع\nبعض\nوتالت مثال الـ ferronickel nickel مع\nالحديد\nوده اللي الكتاب قاله ثبات الـ radius بيفسر\nليه بنعمل منهم alloys كتير\nطب الـ cobalt قد الحديد بالظبط الحجم ده\nلوحده كفاية وقّفوا وفكّروا\nلأ مش لوحده لازم الـ crystal lattice والـ\nchemical properties كمان\nالخلاصة في الـ substitutional ذرات قد بعض\nبتاخد أماكن بعض\nطب ولو الذرات اتحدت كيميائيًا مع بعض ده\nنوع تالت\nحديد و carbon تاني بس المرة دي ليهم\nformula ثابتة إزاي\nده الـ intermetallic alloy العناصر بتتحد\nكيميائيًا وتعمل chemical compound جديد\nفمش كل alloy يبقى compound ده النوع الوحيد\nفيهم اللي فيه اتحاد كيميائي\nأول مثال الـ duralumin aluminum مع nickel\nأو aluminum مع copper كمان\nتاني مثال سبيكة الـ lead والـ gold اتنين\ngold لكل lead واحد\nوتالت مثال الـ cementite تلاتة iron لكل\ncarbon واحد\nفاكرين الـ valency بنبدّل أرقام الـ\nvalency عشان نكتب أي formula صح\nوالكتاب بيقول الـ formula بتاعته بتخالف\nالـ valence law تعالوا نجرب\nنجرب على الـ cementite هو metal مع\nnon-metal فينفع نبدّل\nلو الـ iron اتنين والـ carbon أربعة نبدّل\nونختصر اتنين iron لكل carbon واحد\nولو الـ iron تلاتة جربوا انتوا الأول بسرعة\nأربعة iron وتلاتة carbon برضه مش هي\nولا واحدة طلعت تلاتة لواحد يعني بتخالف الـ\nvalence law فعلًا\nوكمان الـ metals اللي فيه مش من نفس الـ\ngroup في الجدول\nالـ steel نوعه interstitial الـ carbon\nقاعد في الـ spaces بس\nإنما الـ cementite نوعه intermetallic الـ\niron والـ carbon متحدين\nطب metal افتراضي الـ valency بتاعه واحد بس\nومع الـ carbon ليه formula ثابتة اتنين\nmetal لكل carbon أنهي نوع وقّفوا وفكّروا\nالـ valence law بتدّي أربعة لواحد مش اتنين\nفهو intermetallic أكيد\nالخلاصة الـ intermetallic هو chemical\ncompound والـ formula بتاعته بتكسر الـ\nvalence law كده\nيلا نلم الحلقة كلها في سلسلة واحدة\nالـ alloy اتنين metals أو أكتر أو metal مع\nnon-metal كمان\nوبنحضّره بالـ melting أو بالـ\nelectro-deposition من محلول واحد\nوالـ interstitial ذرات صغيرة زي الـ carbon\nفي الـ spaces بين الذرات\nوالـ substitutional ذرات قد بعض بتبدّل\nأماكن بعض\nوالـ intermetallic اتحاد كيميائي و formula\nبتخالف الـ valence law كمان\nوإجابة سؤالنا الـ steel أصلب عشان ذرات الـ\ncarbon بتمنع الطبقات تتزحلق\nمحلول فيه nickel ions و chromium ions\nبيترسبوا على حتة الطريقة إيه وقّفوا\nوفكّروا\nالإجابة الـ electro-deposition والحتة\nنفسها هي الـ cathode هنا\nسؤال الكتاب الـ chromium مع الحديد بيعملوا\nأنهي نوع alloy وقّفوا وفكّروا\nالإجابة substitutional لأن ذراتهم قد بعض\nتقريبًا\nوآخر سؤال النوع اللي عناصره متحدة\nكيميائيًا اسمه إيه وقّفوا وفكّروا\nالإجابة الـ intermetallic زي الـ cementite\nمثلًا\nالحلقة الجاية الـ properties بتاعة الحديد\nنفسه","countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"series_id":"chem-s3-en.ch1#sessions","episode_no":7,"episode_count":9,"lessons":["chem-s3-en.lesson-alloy.definition-preparation","chem-s3-en.lesson-alloy.intermetallic","chem-s3-en.lesson-alloy.interstitial","chem-s3-en.lesson-alloy.substitutional","chem-s3-en.lesson-chem.electroplating-basic","chem-s3-en.lesson-chem.valency-formulas"]},{"id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","version":4,"ord":460,"content_lang":"ar-EG","primary_concept_id":"fe.physical-properties","concepts":[{"concept_id":"fe.physical-properties","role":"primary"},{"concept_id":"fe.passivity","role":"secondary"},{"concept_id":"fe.reaction-conc-sulfuric","role":"secondary"},{"concept_id":"fe.reaction-dilute-acids","role":"secondary"},{"concept_id":"fe.reactions-air-steam","role":"secondary"},{"concept_id":"fe.reactions-nonmetals","role":"secondary"}],"title":"Properties of iron","payload":{"title":"Properties of iron","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"16:9","format":"episode","script":[{"id":"c1","visual":"[CORE] COLD OPEN · FB. EPISODE MODELS (reuse in every part, same colour and position, E11): (a) BAR = a pure-iron bar / nail, steel grey '#8FA3BF' (same grey as the alloys episode); red hot = the same bar glowing orange-red under a flame (HEAT). (b) FLASK = YK.beaker on the stage (x 790–1824) with a pale acid, a tag 'dilute' or 'concentrated' on the glass; iron nail/filings grey; H₂ = small white bubbles rising; SO₂ = pale yellow-grey wisps '#E8D27A' leaving the mouth (a gas, not an ion colour). (c) EQ = YK.formula rows (≥ 48 px, JetBrains Mono digits) in the text panel, built term by term on cue, condition over the arrow (Δ, 500 °C, dil., conc.); ≤ 4 rows; a counted coefficient pulses gold. (d) OX-LADDER = the episode's thread (answers the big question): a vertical ladder at the stage's right edge with three rungs '0 Fe', '+2 iron (II)', '+3 iron (III)'; an iron token (grey disc 'Fe') climbs to the rung of each product and stays as a small marker; rung accents are neutral UI colours (+2 teal '#2DE2E6', +3 gold '#FFC94D'), never ion colours (G44). (e) LAYER = YK.oxideSkin({metal:'Fe', porous:false, p (film coverage), acid, acidLabel:'HNO3'}) (lib/matter.js; same model as video-short-te.chromium-oxide-layer, which uses metal:'Cr'): a thin oxide film grows on the iron, acid particles bounce off it; sandpaper strokes or a dilute-acid drop drive p back to 0. No ion colours anywhere; no references to shorts or other videos. Shot: FLASK, a grey iron nail drops into the dilute acid at frame 0 (already on screen, drift ≤ 2%); H₂ bubbles stream from it on cue 'بيفور'; the nail thins on cue 'وبيدوب'; tag 'dilute acid' on cue 'dilute'.  KIT MAP (lib/episode.js; template must also load lib/short.js, lib/chem.js, lib/matter.js, lib/lab.js, lib/flow.js): segment cards = YK.partCard (no 'sub' field: the part's angle lives in the objective); prereq chip = YK.prereqChip; PREDICT / QUICK CHECK / RECALL = YK.predictCard({kind, q: screen_text}) (think ring included, only the question during the silence) + YK.answerSlot for the answer; misconception rows = YK.mythLine (coral, smaller than the fix); micro-recaps = YK.takeaway centred (full-bleed) as written, pulse words are SINGLE words of the card (multi-word pulses never fire). Text-panel (TP) shots never more than 3 in a row: lines marked FB in this director pass break the runs. Gas jars: Cl₂ a pale gas jar labelled 'Cl₂'; product solids carry labels, no product colours beyond the book (G37/G45).","tts_text":"مسمار حديد في dilute acid: بيفور، وبيدوب قدام عينك.","screen_text":"Iron nail + dilute acid: it fizzes and dissolves"},{"id":"c2","visual":"[CORE] FB split (E7, first-mentioned left): left the fizzing c1 flask (dimmed); right a second FLASK tagged 'concentrated nitric acid' on cue 'concentrated'; the nail goes in, a few bubbles, then nothing: the bubbles stop on cue 'بيقف'; a small '!' pops.","tts_text":"نفس المسمار، في concentrated nitric acid… والتفاعل بيقف خالص.","screen_text":"Same nail + concentrated nitric acid: the reaction stops!"},{"id":"c3","visual":"[CORE] PREREQ chem.solution-concentration [RECAP-PREREQ] (cold open, first use, ≤ 8 s, reference only) · the c2 split stays; a particle inset under each flask: few gold acid dots among many water dots (left, 'dilute') on cue 'قليل', crowded gold dots (right, 'concentrated') on cue 'العكس'; YK.prereqChip 'Concentrated and dilute solutions', out at line end.","tts_text":"الـ dilute يعني acid قليل في مية كتير، والـ concentrated العكس.","screen_text":"Dilute: a little acid in a lot of water · concentrated: the opposite"},{"id":"c4","visual":"[CORE] FB: OX-LADDER appears on the right; a pale gas jar labelled 'Cl₂' on cue 'chlorine' sends the Fe token to '+3' on cue 'تلاتة'; a yellow sulphur powder dish on cue 'sulphur' sends a second token to '+2' on cue 'اتنين'.","tts_text":"ومع الـ chlorine يبقى iron تلاتة، ومع الـ sulphur iron اتنين بس.","screen_text":"Iron + chlorine → iron (III) · iron + sulphur → iron (II)"},{"id":"c5","style":"curious","visual":"[CORE] BIG QUESTION · FB. Previous shots shrink into three thumbnails; card centred (Cairo 1000 84) 'What decides what iron becomes?' on line start, 'decides' gold on cue 'بيقرر'; held through the pause, then shrinks to a gold tag top-right (answered in z7).","tts_text":"نفس الحديد، ونواتج مختلفة… مين اللي بيقرر؟","screen_text":"What decides what iron becomes?","pause_after_s":1},{"id":"t1","visual":"[CORE] TITLE CARD (≤ 4 s from line start). YK.titleCard({title:'Properties of iron', chip:'Unit 8', subtitle:'Chapter 1: Transition Elements'}) Cairo 1000 ≤ 120; 'Properties' gold on cue 'properties'; parts row under it (YK.para Cairo 800 32, maxWidth 800): 1 Physical properties of iron · 2 Effect of air and water vapour · 3 Iron with non-metals: chlorine and sulphur · 4 Iron with dilute acids: equations · 5 Iron with dilute acids: the reason · 6 Iron with hot concentrated sulphuric acid · 7 Passivity of iron. Then camera move (1.2 s, no fade) onto item 1, which grows into the PART 1 card.","tts_text":"الحلقة دي عن الـ properties بتاعة الحديد، الفيزيائية والكيميائية.","screen_text":"Properties of iron","pause_after_s":2.5},{"id":"s1l1","style":"curious","visual":"PART 1/7 · fe.physical-properties · objective: Describe the physical properties of pure iron. · [CORE] Segment card in t1's 2.5 s pause (camera move in, no fade): YK.partCard({num:1, of:7, title:'Physical properties of iron', objective:'Describe the physical properties of pure iron', at: cueEnd(previous line)+0.1, collapse: YK.cue('s1l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Physical properties of iron', never cut) on line start, chip kept to the micro-recap. Line: FB a bridge silhouette; a pure-iron beam (BAR) slides into place on cue 'نبني'; a '?' on cue 'كوبري'. RE-HOOK.","tts_text":"الحديد النقي، ينفع نبني بيه كوبري؟","screen_text":"Pure iron: good enough to build a bridge?"},{"id":"s1l2","visual":"PREREQ chem.metal-properties [RECAP-PREREQ] (ONE line, ≤ 8 s, reference only; E2b one prereq per segment: density is shown, not recapped, in s1l7). TP. Prereq YK.chip (link icon) 'Properties of metals and non-metals' under the segment chip. Stage, same model as video-short-chem.metal-properties: YK.hammer drives YK.lattice slip, the block spreads into a sheet on cue 'malleable', then is pulled into a wire on cue 'ductile'; labels on the same cues. Prereq chip out at line end.","tts_text":"فاكرين؟ الـ malleable بيتطرق ألواح، والـ ductile بيتسحب أسلاك.","screen_text":"Malleable: hammered into sheets · ductile: drawn into wires"},{"id":"s1l3","visual":"[CORE] Book list p.20 (E2c-style: ONE table 'Pure iron (p.20)', one row per line; no new terms: every row is a recapped or known word). TP table row 1 'relatively soft, low hardness' on cue 'طري'; stage: the BAR bends under a thumb press on cue 'hardness'.","tts_text":"الكتاب بيقول: الحديد النقي طري نسبيًا، والـ hardness بتاعته قليلة.","screen_text":"Pure iron: relatively soft, with low hardness"},{"id":"s1l4","visual":"[CORE] Table row 2 'malleable, ductile' on cue 'malleable'; stage: the BAR hammered flat on cue 'malleable', drawn into a wire on cue 'ductile'.","tts_text":"وهو malleable و ductile، يعني بيتشكل بسهولة.","screen_text":"Malleable and ductile"},{"id":"s1l5","visual":"[CORE] FB (breaks the text-panel run): a large YK.magnet on the right pulls the BAR across the frame on cue 'بيشده'; tag 'magnetic properties' on the bar on cue 'magnetic' (table row 3 added when the table returns on s1l6).","tts_text":"وكمان ليه magnetic properties، والمغناطيس بيشده.","screen_text":"Magnetic properties"},{"id":"s1l6","visual":"[CORE] Table row 4 'melts at 1538 °C' (YK.label, JetBrains Mono digits) on cue 'وبيدوب'; stage: a thermometer climbs to 1538 on cue 'درجة', the BAR drips.","tts_text":"وبيدوب عند ألف خمسمية تمانية وتلاتين درجة.","screen_text":"Melts at 1538 °C"},{"id":"s1l7","visual":"[CORE] FB close-up (breaks the text-panel run; shows what density means, replaces the cut s1l3 recap): a grey iron cube tagged '1 cm³' on a YK.balance, readout '7.87 g' on cue 'جرام'; table row 5 'density 7.87 g/cm³' as a tag on cue 'density'. Book table complete (5 rows) when the table returns on s1l8.","tts_text":"والـ density بتاعته سبعة فاصل سبعة وتمانين جرام لكل سنتيمتر مكعب.","screen_text":"Density: 7.87 g/cm³"},{"id":"s1l8","visual":"[CORE] TP misconception row 'Pure iron is very hard' + small YK.wrongMark on cue 'لأ' (< 2 s; G40, fe.physical-properties misconception #1); stage: the BAR bends again on cue 'طري'.","tts_text":"ناس كتير فاكرة إن الحديد النقي ناشف جدًا… لأ، ده طري.","screen_text":"Common mistake: pure iron is very hard ✗"},{"id":"s1l9","visual":"[CORE] FB: the s1l1 bridge beam sags; stamp 'no industrial importance' on cue 'الصناعة' (book p.20; misconception #2 'pure iron is the most useful form' refuted).","tts_text":"وعشان هو طري، الحديد النقي ملوش أهمية في الصناعة.","screen_text":"So pure iron has no industrial importance"},{"id":"s1l10","visual":"[CORE] TP book line on cue 'physical'; stage: three bars of different purity, small coloured impurity dots inside two of them, pop in on cue 'impurities'.","tts_text":"والـ physical properties بتاعته بتعتمد على نقاوته، وعلى نوع الـ impurities اللي فيه.","screen_text":"Its physical properties depend on its purity and impurities"},{"id":"s1l11","visual":"[CORE] FB: the bars fan out into labelled tools (rail, spoon, magnet core) tagged 'steels' on cue 'steel' and 'iron alloys' on cue 'alloys' (book p.20).","tts_text":"فبنعمل منه أنواع steel و alloys كتير.","screen_text":"→ many steels and iron alloys, each suited to a use"},{"id":"s1l12","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: a melting point that is not the book's; not in the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: a sample on a hot plate, thermometer reading 1450 on cue 'عينة'; the book's '1538 °C' row glows faintly; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"عينة حديد بتدوب عند ألف ربعمية وخمسين درجة… دي حديد نقي؟ وقّفوا وفكّروا.","screen_text":"An iron sample melts at 1450 °C. Is it pure iron?","pause_after_s":3},{"id":"s1l13","visual":"[CORE] TP answer 'Not pure ✓' with YK.rightMark on cue 'لأ'; tag 'melting point' on cue 'melting'; the s1l10 book line pulses on cue 'النقاوة'.","tts_text":"لأ، مش نقي: الـ melting point من الـ physical properties، وبيعتمد على النقاوة.","screen_text":"Not pure ✓ the melting point is a physical property: it depends on purity"},{"id":"s1l14","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Physical properties of iron', line:'Relatively soft, malleable, ductile, magnetic · melts at 1538 °C · 7.87 g/cm³', pulse:[{word:'soft', at:YK.cue('s1l14','طري')}, {word:'magnetic', at:YK.cue('s1l14','magnetic')}]}).","tts_text":"الخلاصة: الحديد النقي طري، و malleable و ductile، وليه magnetic properties كمان.","screen_text":"Pure iron: relatively soft, malleable, ductile, magnetic"},{"id":"s1l15","visual":"[CORE] SO-WHAT · FB: the BAR turns red hot under a flame on cue 'كيميائيًا'. Segment chip out; in the pause: camera move into the PART 2 card.","tts_text":"ده الحديد من بره… طب كيميائيًا، بيتفاعل إزاي؟","screen_text":"That's iron from the outside. How does it react?","pause_after_s":2.5},{"id":"s2l1","style":"curious","visual":"PART 2/7 · fe.reactions-air-steam · objective: Write the equations of red hot iron with air and with water vapour. · [CORE] Segment card in s1l15's 2.5 s pause (camera move in, no fade): YK.partCard({num:2, of:7, title:'Effect of air and water vapour', objective:'Write the equations of red hot iron with air and with water vapour', at: cueEnd(previous line)+0.1, collapse: YK.cue('s2l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Effect of air and water vapour', never cut) on line start, chip kept to the micro-recap. Line: FB HEAT: the BAR glows red on cue 'يحمر'; a dry-air stream (light arrows) on cue 'هوا'; a '?' on cue 'إيه'. RE-HOOK.","tts_text":"نسخّن الحديد لحد ما يحمر، ونعدّي عليه هوا ناشف… يطلع إيه؟","screen_text":"Iron heated until it glows red, in dry air. What forms?"},{"id":"s2l2","visual":"PREREQ redox.basic [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Oxidation and reduction by oxygen'. Stage: an O atom (red) joins a grey atom on cue 'oxidation' (tag 'gain of oxygen'), leaves it on cue 'reduction' (tag 'loss of oxygen'). Prereq chip out at line end.","tts_text":"فاكرين؟ الـ oxidation إن المادة تاخد oxygen، والـ reduction إنها تخسره.","screen_text":"Oxidation: gain of oxygen · reduction: loss of oxygen"},{"id":"s2l3","visual":"[CORE] FB HEAT: the red-hot BAR in a jar; O₂ molecules (red pairs) drift onto it on cue 'oxygen'; tag 'red hot iron' on cue 'أحمر'.","tts_text":"الحديد وهو أحمر من السخونية، مع oxygen أو هوا ناشف،","screen_text":"Red hot iron + dry air or oxygen"},{"id":"s2l4","visual":"[CORE] FB: the bar's surface turns black on cue 'magnetic' (NEW TERM 1/3 'magnetic iron oxide', label on the same cue); a small YK.magnet tugs the black flakes on cue 'وبيتشد'.","tts_text":"بيدّي الـ magnetic iron oxide، أسود وبيتشد للمغناطيس.","screen_text":"→ magnetic iron oxide: black, attracted by a magnet"},{"id":"s2l5","visual":"[CORE] TP EQ row 1 builds: '3Fe(s)' on cue 'تلاتة', '+ 2O₂(g)' on cue 'اتنين', '→Δ Fe₃O₄(s)' on cue 'يدّوا' (book p.21).","tts_text":"المعادلة: تلاتة iron، مع اتنين جزيء oxygen، يدّوا جزيء واحد منه.","screen_text":"3Fe(s) + 2O₂(g) →Δ Fe₃O₄(s)"},{"id":"s2l6","visual":"[CORE] TP: the Fe → Fe₃O₄ arrow gets a gold tag 'oxidation' on cue 'oxidation'; stage: OX-LADDER shows only a small 'oxidized' tick (no state named yet).","tts_text":"الحديد هنا خد oxygen، يعني ده oxidation للحديد.","screen_text":"Iron gains oxygen: oxidation"},{"id":"s2l7","visual":"[CORE] FB (shot change): a glass tube, the BAR red hot inside, thermometer tag '500 °C' on cue 'خمسمية'; white steam enters from the left on cue 'بخار'.","tts_text":"ولو بدل الهوا، عدّينا بخار مَيّة على حديد خمسمية درجة؟","screen_text":"Red hot iron (500 °C) + water vapour?"},{"id":"s2l8","visual":"[CORE] FB tube: the bar blackens on cue 'magnetic'; H₂ bubbles leave the right end on cue 'hydrogen' (tag 'hydrogen gas').","tts_text":"يطلع نفس الـ magnetic iron oxide، ومعاه hydrogen غاز طالع.","screen_text":"→ magnetic iron oxide + hydrogen gas"},{"id":"s2l9","visual":"[CORE] TP EQ row 2 builds: '3Fe(s) + 4H₂O(v)' on cue 'أربعة', '→500 °C Fe₃O₄(s)' on cue 'oxide', '+ 4H₂(g)' on cue 'طالعين'; the two 4s pulse gold.","tts_text":"تلاتة iron مع أربعة بخار مَيّة، يدّوا الـ oxide، وأربعة hydrogen طالعين.","screen_text":"3Fe(s) + 4H₂O(v) →500 °C Fe₃O₄(s) + 4H₂(g)"},{"id":"s2l10","visual":"[CORE] TP refutation (G40, fe.reactions-air-steam misconceptions #1 and #2): ghost formulas 'Fe(OH)₂' on cue 'hydroxide' and 'Fe₂O₃' on cue 'تلاتة', each with a small YK.wrongMark (< 2 s each).","tts_text":"وخدوا بالكم: مش بيطلع hydroxide، ولا iron تلاتة oxide هنا.","screen_text":"Not Fe(OH)₂ ✗ · not Fe₂O₃ ✗"},{"id":"s2l11","visual":"[CORE] FB close-up: an H₂O molecule hands its O atom to the iron on cue 'خسر'; tag 'reduction' on cue 'reduction'; the two H atoms leave as H₂ on cue 'وطلع'.","tts_text":"بخار المية خسر الـ oxygen بتاعه، فحصله reduction، وطلع hydrogen في الآخر.","screen_text":"Water vapour loses its oxygen: it is reduced to hydrogen"},{"id":"s2l12","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: iron wool in pure oxygen + a magnet; not in the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: iron wool sparks in a jar of oxygen on cue 'بيولّع'; black lumps fall; a magnet hovers on cue 'للمغناطيس'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"سلك مواعين حديد بيولّع في oxygen نقي. الناتج الأسود هيتشد للمغناطيس؟ وقّفوا وفكّروا.","screen_text":"Iron wool burns in pure oxygen. Will the black product stick to a magnet?","pause_after_s":3},{"id":"s2l13","visual":"[CORE] FB: the black lumps jump to the magnet with YK.rightMark on cue 'أيوه'; label 'magnetic iron oxide, Fe₃O₄' on cue 'magnetic'.","tts_text":"أيوه: ده الـ magnetic iron oxide، زي ما الاسم بيقول.","screen_text":"Yes ✓ it is magnetic iron oxide, Fe₃O₄"},{"id":"s2l14","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Effect of air and water vapour', line:'Red hot iron + air (Δ) or water vapour (500 °C) → magnetic iron oxide', formula:'Fe₃O₄', pulse:[{word:'magnetic', at:YK.cue('s2l14','magnetic')}]}).","tts_text":"الخلاصة: الهوا أو بخار المية على حديد أحمر، يدّوا الـ magnetic iron oxide كده.","screen_text":"Red hot iron + air or water vapour → magnetic iron oxide"},{"id":"s2l15","visual":"[CORE] SO-WHAT · FB: a chlorine gas jar and a sulphur dish slide in, an 'O' crossed out over them on cue 'مفيهوش'. Segment chip out; in the pause: camera move into the PART 3 card.","tts_text":"طب ولو الشريك مفيهوش oxygen خالص؟","screen_text":"And with partners that have no oxygen at all?","pause_after_s":2.5},{"id":"s3l1","style":"curious","visual":"PART 3/7 · fe.reactions-nonmetals · objective: Compare the reactions of iron with chlorine and with sulphur. · [CORE] Segment card in s2l15's 2.5 s pause (camera move in, no fade): YK.partCard({num:3, of:7, title:'Iron with non-metals: chlorine and sulphur', objective:'Compare the reactions of iron with chlorine and with sulphur', at: cueEnd(previous line)+0.1, collapse: YK.cue('s3l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron with non-metals: chlorine and sulphur', never cut) on line start, chip kept to the micro-recap. Line: FB split (E7, first-mentioned left): left a pale gas jar labelled 'Cl₂' on cue 'chlorine', right a yellow sulphur dish on cue 'sulphur'; a hot iron wire hovers between; '?' on cue 'هيتفاعل'. RE-HOOK.","tts_text":"الـ chlorine والـ sulphur مفيهمش oxygen… الحديد هيتفاعل معاهم برضه؟","screen_text":"Chlorine and sulphur: no oxygen. Does iron still react?"},{"id":"s3l2","visual":"PREREQ pt.oxidation-number [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Oxidation state in compounds'. Tags 'Cl: −1' on cue 'واحد' and 'S: −2' on cue 'اتنين'; OX-LADDER on the right lights on cue 'oxidation'. Prereq chip out at line end.","tts_text":"فاكرين الـ oxidation state؟ الـ chlorine سالب واحد، والـ sulphur سالب اتنين.","screen_text":"Oxidation state: Cl −1 · S −2"},{"id":"s3l3","visual":"[CORE] FB: the hot iron wire glows in the chlorine jar on cue 'بالتسخين'; a solid product forms on the wire (neutral grey, no colour claim, G37/G45), label 'iron (III) chloride' on cue 'chloride'.","tts_text":"الحديد مع الـ chlorine بالتسخين، بيدّي iron تلاتة chloride على طول.","screen_text":"Iron + chlorine (heat) → iron (III) chloride"},{"id":"s3l4","visual":"[CORE] TP EQ row 1 builds: '2Fe(s)' on cue 'اتنين', '+ 3Cl₂(g)' on cue 'تلاتة', '→Δ 2FeCl₃(s)' on cue 'يدّوا' (book p.21).","tts_text":"اتنين iron مع تلاتة chlorine، يدّوا اتنين من الـ chloride ده.","screen_text":"2Fe(s) + 3Cl₂(g) →Δ 2FeCl₃(s)"},{"id":"s3l5","visual":"[CORE] TP: under FeCl₃, three '−1' tags on cue 'ذرات', sum '−3' on cue 'سالب'; stage: OX-LADDER, the Fe token climbs to '+3 iron (III)' on cue 'موجب'.","tts_text":"تلات ذرات chlorine، كل واحدة سالب واحد، يبقى الحديد تلاتة موجب.","screen_text":"3 Cl × (−1) = −3 → iron +3"},{"id":"s3l6","visual":"[CORE] FB: iron filings + sulphur powder heated in a dish glow on cue 'بالتسخين'; a dark solid, label 'iron (II) sulphide' on cue 'sulphide'.","tts_text":"أما مع الـ sulphur بالتسخين، بيدّي iron اتنين sulphide بس.","screen_text":"Iron + sulphur (heat) → iron (II) sulphide"},{"id":"s3l7","visual":"[CORE] TP EQ row 2 'Fe(s) + S(s) →Δ FeS(s)' builds on cue 'ذرة'; tag '−2' under S on cue 'سالب'; OX-LADDER: a second token stops at '+2 iron (II)' on cue 'موجب'.","tts_text":"ذرة iron مع ذرة sulphur، والـ sulphur سالب اتنين، فالحديد اتنين موجب.","screen_text":"Fe(s) + S(s) →Δ FeS(s) · S −2 → iron +2"},{"id":"s3l8","visual":"[CORE] FB split (E7, chlorine left): two arrows pulling the Fe token up the OX-LADDER: a thick gold arrow on cue 'قوي' (tag 'strong oxidizing agent'), a thinner one on cue 'أضعف' (tag 'weaker').","tts_text":"ليه الفرق؟ الـ chlorine ده oxidizing agent قوي، والـ sulphur أضعف منه.","screen_text":"Chlorine: a strong oxidizing agent · sulphur: weaker"},{"id":"s3l9","visual":"[CORE] FB OX-LADDER: the thick arrow lifts its token to '+3' on cue 'لتلاتة'; the thin one stops at '+2' on cue 'بيوقّفه'.","tts_text":"الأقوى بيوصّل الحديد لتلاتة موجب، والأضعف بيوقّفه عند اتنين.","screen_text":"Stronger → iron +3 · weaker → iron stops at +2"},{"id":"s3l10","visual":"[CORE] TP refutation (G40, misconception #2): ghost 'FeSO₄' + small YK.wrongMark on cue 'لأ' (< 2 s); an 'O' crossed out on cue 'مفيش'.","tts_text":"وفي ناس بتكتب sulphate هنا… لأ، مفيش oxygen أصلًا، فمفيش sulphate خالص.","screen_text":"Fe + S → FeSO₄ ✗ no oxygen → no sulphate"},{"id":"s3l11","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: the book's equation scaled to 4 Fe; not in the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: four grey Fe discs on cue 'أربع' next to the s3l4 EQ row (dimmed); YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"أربع ذرات iron مع الـ chlorine: محتاجين كام chlorine، ويطلع كام chloride؟ وقّفوا وفكّروا.","screen_text":"4 Fe atoms + chlorine: how many Cl₂? How many FeCl₃?","pause_after_s":3},{"id":"s3l12","visual":"[CORE] TP: '4Fe + 6Cl₂ → 4FeCl₃' builds: '6' on cue 'ستة', '4' on cue 'أربعة'; '× 2' tag over the book row on cue 'متضاعفة' + YK.rightMark.","tts_text":"ستة chlorine، ويطلع أربعة iron تلاتة chloride… يعني المعادلة متضاعفة.","screen_text":"6Cl₂ → 4FeCl₃ ✓ the book's equation doubled"},{"id":"s3l13","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron with non-metals: chlorine and sulphur', line:'Chlorine → iron (III) chloride · sulphur → iron (II) sulphide', formula:'FeCl₃ · FeS', pulse:[{word:'chlorine', at:YK.cue('s3l13','chlorine')}, {word:'sulphur', at:YK.cue('s3l13','sulphur')}]}).","tts_text":"الخلاصة: الـ chlorine يدّي iron تلاتة، والـ sulphur يدّي iron اتنين.","screen_text":"Chlorine → FeCl₃ (iron +3) · sulphur → FeS (iron +2)"},{"id":"s3l14","visual":"[CORE] SO-WHAT · FB: a row of acid bottles slides in at the bottom on cue 'acids'. Segment chip out; m1 follows.","tts_text":"قبل الـ acids، نلم اللي فات بسرعة.","screen_text":"Before the acids: a quick recap","pause_after_s":1},{"id":"m1l1","visual":"[CORE] MID-EPISODE RECAP 1 (after Parts 1-3) · FB. YK.flow({rtl:false, layout:'row', area:{x:96,y:380,w:1728,h:320}, node:{size:40}}); header 'So far' (Cairo 800 40). Node 1 'Pure iron' (sub 'soft · depends on purity') lit on cue 'طري'.","tts_text":"نلم اللي فات: الحديد النقي طري، وخواصه بتعتمد على نقاوته.","screen_text":"Pure iron: relatively soft · depends on purity"},{"id":"m1l2","visual":"[CORE] Flow: arrow + node 2 'Air / water vapour' (sub 'Fe₃O₄') lit on cue 'magnetic'.","tts_text":"والهوا أو بخار المية على الحديد الأحمر، بيدّوا الـ magnetic iron oxide كمان.","screen_text":"Air or water vapour → magnetic iron oxide"},{"id":"m1l3","visual":"[CORE] Flow: node 3 'Non-metals' with two sub-tags: 'Cl₂ → +3' on cue 'chlorine', 'S → +2' on cue 'sulphur'. In the pause: camera move into the PART 4 card.","tts_text":"والـ chlorine يدّي iron تلاتة، والـ sulphur يدّي iron اتنين.","screen_text":"Chlorine → iron (III) · sulphur → iron (II)","pause_after_s":2.5},{"id":"s4l1","style":"curious","visual":"PART 4/7 · fe.reaction-dilute-acids · objective: Write the equations of iron with dilute mineral acids. · [CORE] Segment card in m1l3's 2.5 s pause (camera move in, no fade): YK.partCard({num:4, of:7, title:'Iron with dilute acids', objective:'Write the equations of iron with dilute mineral acids', at: cueEnd(previous line)+0.1, collapse: YK.cue('s4l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron with dilute acids', never cut) on line start, chip kept to the micro-recap. Line: FB FLASK (the c1 flask returns) on cue 'dilute'; OX-LADDER with an empty '?' token between '+2' and '+3' on cue 'ولا'. RE-HOOK.","tts_text":"الحديد في dilute acid: هيدّي iron اتنين، ولا iron تلاتة؟","screen_text":"Iron + dilute acid: iron (II) or iron (III)?"},{"id":"s4l2","visual":"PREREQ acid.metal-acid-reaction [RECAP-PREREQ] (ONE line, ≤ 8 s, reference only; chem.solution-concentration is recapped in the cold open). TP. Prereq YK.chip (link icon) 'Metal + dilute acid'. Stage: a short activity column with the metal tile above 'H' on cue 'فوق'; a generic metal strip in acid fizzes on cue 'بيطلع'; word equation 'metal + dilute acid → salt + hydrogen' builds on cue 'salt'.","tts_text":"فاكرين؟ metal فوق الـ hydrogen، مع dilute acid، يدّي salt، والـ hydrogen بيطلع.","screen_text":"Metal above hydrogen + dilute acid → salt + hydrogen"},{"id":"s4l3","visual":"[CORE] FB FLASK: the nail dissolves with H₂ bubbles on cue 'بيدوب'; TP book line 'Iron dissolves in dilute mineral acids' on cue 'mineral'.","tts_text":"الحديد بيدوب في الـ mineral acids، الـ dilute منها.","screen_text":"Iron dissolves in dilute mineral acids"},{"id":"s4l4","visual":"[CORE] TP: 'iron (II) salts' gold on cue 'اتنين'; 'not iron (III) salts' dim (no strike-through) on cue 'مش'; OX-LADDER: the '?' token drops to '+2' on cue 'اتنين'.","tts_text":"ويدّي iron اتنين salts، مش iron تلاتة.","screen_text":"→ iron (II) salts, not iron (III) salts"},{"id":"s4l5","visual":"[CORE] TP EQ row 1 builds: 'Fe(s) + H₂SO₄(aq)' on cue 'sulphuric', '→dil. FeSO₄(aq)' on cue 'sulphate', '+ H₂(g)' on cue 'بيفور' (book p.21); stage: bubbles.","tts_text":"مع الـ dilute sulphuric acid، يطلع iron اتنين sulphate، والـ hydrogen بيفور.","screen_text":"Fe(s) + H₂SO₄(aq) →dil. FeSO₄(aq) + H₂(g)"},{"id":"s4l6","visual":"[CORE] FB close-up (breaks the text-panel run): the FLASK of dilute HCl full-bleed, the nail fizzing; EQ row 2 as a formula strip (y 900, mono ≥ 56) builds: 'Fe(s) + 2HCl(aq)' on cue 'hydrochloric', '→dil. FeCl₂(aq)' on cue 'chloride', '+ H₂(g)' on cue 'برضه' (book p.21); both rows are back in the text panel on s4l7.","tts_text":"ومع الـ hydrochloric acid الـ dilute: iron اتنين chloride، و hydrogen برضه.","screen_text":"Fe(s) + 2HCl(aq) →dil. FeCl₂(aq) + H₂(g)"},{"id":"s4l7","visual":"[CORE] TP: the '2' of 2HCl pulses gold on cue 'ليه'; under FeCl₂ two '−1' tags on cue 'ذرتين' balance one '+2' tag on cue 'موجب'.","tts_text":"ليه اتنين hydrochloric؟ الحديد اتنين موجب، محتاج ذرتين chlorine معاه.","screen_text":"Why 2HCl? Iron +2 needs two Cl"},{"id":"s4l8","visual":"[CORE] FB (breaks the text-panel run): the FLASK fizzes harder on cue 'بيفور'; small YK.mythLine 'Iron does not react with dilute acids' + ✕ on cue 'لأ' at the top-left under the chip (< 2 s; G40, fe.reaction-dilute-acids misconception #2).","tts_text":"وناس فاكرة إن الحديد مش بيتفاعل مع dilute acids… لأ، ده بيفور.","screen_text":"Common mistake: iron does not react with dilute acids ✗"},{"id":"s4l9","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: the book's HCl equation scaled to 2 Fe; not in the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: two grey Fe discs on cue 'ذرتين' beside the dimmed EQ row 2; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"ذرتين iron في الـ hydrochloric acid: كام acid، وكام hydrogen؟ وقّفوا وفكّروا.","screen_text":"2 Fe atoms + hydrochloric acid: how many HCl? How many H₂?","pause_after_s":3},{"id":"s4l10","visual":"[CORE] TP: '2Fe + 4HCl → 2FeCl₂ + 2H₂' builds: '4HCl' on cue 'أربعة', '2H₂' on cue 'hydrogen', '2FeCl₂' on cue 'chloride' + YK.rightMark.","tts_text":"أربعة acid، واتنين hydrogen، ومعاهم اتنين من الـ chloride بتاعنا.","screen_text":"4HCl → 2FeCl₂ + 2H₂ ✓"},{"id":"s4l11","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron with dilute acids', line:'Iron + dilute mineral acids → iron (II) salt + hydrogen', formula:'FeSO₄ · FeCl₂', pulse:[{word:'II', at:YK.cue('s4l11','اتنين')}, {word:'hydrogen', at:YK.cue('s4l11','hydrogen')}]}).","tts_text":"الخلاصة: الحديد مع الـ dilute acids يدّي iron اتنين salt، و hydrogen كمان.","screen_text":"Iron + dilute acids → iron (II) salt + hydrogen"},{"id":"s4l12","visual":"[CORE] SO-WHAT · FB split: left the chlorine jar (FeCl₃, token at +3), right the HCl flask (FeCl₂, token at +2); '?' between on cue 'ليه'. Segment chip stays (same concept); in the pause: camera move into the PART 5 card.","tts_text":"طب ليه مش iron تلاتة، زي الـ chlorine بالظبط؟","screen_text":"But why not iron (III), as with chlorine?","pause_after_s":2.5},{"id":"s5l1","style":"curious","visual":"PART 5/7 · fe.reaction-dilute-acids · objective: Explain why iron gives iron (II) salts, not iron (III) salts. · [CORE] Segment card in s4l12's 2.5 s pause (camera move in, no fade): YK.partCard({num:5, of:7, title:'Iron with dilute acids', objective:'Explain why iron gives iron (II) salts, not iron (III) salts', at: cueEnd(previous line)+0.1, collapse: YK.cue('s5l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron with dilute acids', never cut) on line start, chip kept to the micro-recap. Line: FB: the HCl flask; a 'Cl' tag glows inside the formula HCl on cue 'chlorine'; FeCl₂ with a '?' on cue 'ليه'. RE-HOOK.","tts_text":"الـ hydrochloric acid فيه chlorine… أمّال ليه iron اتنين chloride، مش تلاتة؟","screen_text":"HCl contains chlorine too. So why FeCl₂, not FeCl₃?"},{"id":"s5l2","visual":"PREREQ redox.electronic [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Oxidation and reduction by electrons'. Stage: an 'e⁻' dot passes from a tile tagged 'reducing agent' on cue 'agent' to a tile tagged 'reduced' on cue 'reduction'. Prereq chip out at line end.","tts_text":"فاكرين؟ الـ reduction إن المادة تاخد electrons، والـ reducing agent هو اللي بيدّيها.","screen_text":"Reduction: gain of electrons · reducing agent: gives electrons"},{"id":"s5l3","visual":"[CORE] TP book line (p.21) on cue 'الكتاب'; stage: inside the FLASK a few '+3' tokens appear near the nail on cue 'بتتكوّن'; H₂ bubbles touch them on cue 'الطالع'.","tts_text":"الكتاب بيقول: أي iron تلاتة salts بتتكوّن، الـ hydrogen الطالع بيعمل لها reduction فورًا.","screen_text":"The book: iron (III) salts are reduced by the produced hydrogen"},{"id":"s5l4","visual":"[CORE] FB zoom into the FLASK: H₂ bubbles rise from the nail surface on cue 'بيطلع', where the iron ions form; ring highlight on cue 'جنب'.","tts_text":"لأن الـ hydrogen بيطلع في نفس الدورق، جنب الحديد بالظبط.","screen_text":"The hydrogen forms right there, in the same flask"},{"id":"s5l5","visual":"[CORE] FB close-up: an 'e⁻' dot from a H₂ bubble to a '+3' token on cue 'electron'; the token becomes '+2' on cue 'ويرجع'; OX-LADDER: the token steps down +3 → +2 on cue 'اتنين'.","tts_text":"فالـ iron تلاتة ياخد electron، ويرجع iron اتنين تاني.","screen_text":"iron (III) + e⁻ → iron (II)"},{"id":"s5l6","visual":"[CORE] TP: tag 'H₂ = reducing agent' on cue 'reducing'; the bubbles pulse gold.","tts_text":"يعني الـ hydrogen هنا هو الـ reducing agent بتاعنا.","screen_text":"Hydrogen: the reducing agent here"},{"id":"s5l7","visual":"[CORE] FB split (chlorine left): the chlorine jar with no bubbles on cue 'مفيهوش'; its token stays at '+3' on cue 'بيفضل'; right the HCl flask token at '+2'.","tts_text":"أما الـ chlorine الغاز، مفيهوش hydrogen، فالـ iron تلاتة بيفضل كده.","screen_text":"Chlorine gas: no hydrogen forms → FeCl₃ stays"},{"id":"s5l8","visual":"[CORE] TP refutation (G40, fe.reaction-dilute-acids misconception #1): the quote + small YK.wrongMark on cue 'غلطان' (< 2 s).","tts_text":"فاللي يقول إن الـ hydrochloric acid زي الـ chlorine بالظبط، غلطان.","screen_text":"'HCl has chlorine, so it gives FeCl₃' ✗"},{"id":"s5l9","visual":"[CORE] PAUSE-AND-PREDICT part 1 (NEW case: dilute hydrobromic acid, a mineral acid the book does not use; the book's rule 'dilute mineral acids → iron (II) salts' applies). TP: YK.predictCard header; a FLASK tagged 'HBr (dil.)' on cue 'hydrobromic', iron nail drops in and fizzes on cue 'الحديد'.","tts_text":"طب الحديد في dilute hydrobromic acid المرة دي،","screen_text":"Iron + dilute hydrobromic acid (HBr)…"},{"id":"s5l10","visual":"[CORE] PAUSE-AND-PREDICT part 2 · YK.predictCard({kind:'PREDICT', q:'Iron + dilute HBr: FeBr₂ or FeBr₃?'}) in the text panel; two empty answer slots 'FeBr₂?' / 'FeBr₃?' on cue 'bromide'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"هيدّي iron اتنين bromide ولا iron تلاتة bromide؟ وقّفوا وفكّروا.","screen_text":"…FeBr₂ or FeBr₃?","pause_after_s":3},{"id":"s5l11","visual":"[CORE] FB close-up (breaks the text-panel run): inside the HBr flask an 'e⁻' passes from a rising H₂ bubble to a '+3' token, which becomes '+2' on cue 'reduction'; YK.answerSlot 'FeBr₂ ✓ iron (II) bromide' on cue 'bromide'; OX-LADDER token steps +3 → +2.","tts_text":"الصح iron اتنين bromide: الـ hydrogen اللي بيطلع بيعمل reduction لأي iron تلاتة.","screen_text":"FeBr₂ ✓ the produced hydrogen reduces any iron (III)"},{"id":"s5l12","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron with dilute acids', line:'Iron (III) salts are reduced by the produced hydrogen → iron (II) salts', pulse:[{word:'hydrogen', at:YK.cue('s5l12','hydrogen')}, {word:'reduced', at:YK.cue('s5l12','reduction')}]}).","tts_text":"الخلاصة: iron اتنين مش تلاتة، عشان الـ hydrogen الطالع بيعمل reduction على طول.","screen_text":"Iron (II), not iron (III): reduced by the produced hydrogen"},{"id":"s5l13","visual":"[CORE] SO-WHAT · FB: band 'Same sulphuric acid, but concentrated and hot?'; the FLASK's tag flips from 'dilute H₂SO₄' to 'concentrated H₂SO₄' on cue 'concentrated'; a flame lights under it on cue 'وسخن'. Segment chip out; in the pause: camera move into the PART 6 card.","tts_text":"طب ولو الـ acid ده concentrated وسخن؟ الحكاية بتتقلب.","screen_text":"Same sulphuric acid, but concentrated and hot?","pause_after_s":2.5},{"id":"s6l1","style":"curious","visual":"PART 6/7 · fe.reaction-conc-sulfuric · objective: Write the equation of iron with hot concentrated sulphuric acid. · [CORE] Segment card in s5l13's 2.5 s pause (camera move in, no fade): YK.partCard({num:6, of:7, title:'Iron with hot concentrated sulphuric acid', objective:'Write the equation of iron with hot concentrated sulphuric acid', at: cueEnd(previous line)+0.1, collapse: YK.cue('s6l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron with hot concentrated sulphuric acid', never cut) on line start, chip kept to the micro-recap. Line: FB FLASK tagged 'concentrated' over a flame on cue 'وسخن'; a H₂ bubble icon with '?' on cue 'hydrogen'. RE-HOOK.","tts_text":"الـ sulphuric acid لما يبقى concentrated وسخن… هيطلع hydrogen تاني؟","screen_text":"Hot concentrated sulphuric acid: hydrogen again?"},{"id":"s6l2","visual":"PREREQ chem.solution-concentration (E2d callback, ≤ 6 s; recapped first in s4l3, adds only 'concentrated') · TP. Prereq YK.chip (link icon) 'Concentrated and dilute solutions'. Stage: the s4l3 particle beaker, now crowded with gold acid dots on cue 'كتير'. Prereq chip out at line end.","tts_text":"والـ concentrated عكس الـ dilute: acid كتير ومية قليلة.","screen_text":"Concentrated: a lot of acid, little water"},{"id":"s6l3","visual":"[CORE] TP product list (book p.21) builds: 'iron (II) sulphate' on cue 'اتنين', 'iron (III) sulphate' on cue 'تلاتة'; OX-LADDER: two tokens, one at '+2', one at '+3', on cue 'بعض'.","tts_text":"بيطلع iron اتنين sulphate، و iron تلاتة sulphate مع بعض.","screen_text":"Products: iron (II) sulphate + iron (III) sulphate"},{"id":"s6l4","visual":"[CORE] FB (breaks the text-panel run): the hot concentrated FLASK full-bleed; pale yellow-grey SO₂ wisps leave the mouth with tag 'sulphur dioxide' on cue 'sulphur'; water-vapour wisps tag 'water' on cue 'ومية'; the product list returns to the text panel on s6l5.","tts_text":"ومعاهم sulphur dioxide غاز، ومية كمان.","screen_text":"+ sulphur dioxide + water"},{"id":"s6l5","visual":"[CORE] TP EQ row 1 builds the left side: '3Fe(s)' on cue 'تلاتة', '+ 8H₂SO₄(l)' on cue 'تمانية', condition '(conc.) Δ' over the arrow on cue 'concentrated' (book p.21).","tts_text":"المعادلة: تلاتة iron، مع تمانية sulphuric acid، الـ concentrated السخن.","screen_text":"3Fe + 8H₂SO₄ (conc., Δ) →"},{"id":"s6l6","visual":"[CORE] FB close-up (breaks the text-panel run): EQ row 1 full width (mono ≥ 56, y 540, x 96–1824) completes its right side: 'FeSO₄(aq) + Fe₂(SO₄)₃(aq)' on cue 'نوع', '+ 4SO₂(g)' on cue 'وأربعة', '+ 8H₂O(v)' on cue 'وتمانية'.","tts_text":"تدّي sulphate من كل نوع، وأربعة sulphur dioxide، وتمانية جزيء مية.","screen_text":"→ FeSO₄ + Fe₂(SO₄)₃ + 4SO₂ + 8H₂O"},{"id":"s6l7","visual":"[CORE] FB: the H₂ icon from s6l1 gets a YK.wrongMark on cue 'مفيش' (< 2 s; G40, misconception #1); SO₂ wisps labelled 'SO₂' on cue 'الغاز'.","tts_text":"يعني مفيش hydrogen هنا… الغاز هو الـ sulphur dioxide نفسه.","screen_text":"Hydrogen? ✗ The gas is sulphur dioxide"},{"id":"s6l8","visual":"[CORE] FB worked count (s6l8–s6l11 are one full-bleed shot, memory pattern: no 4-line text-panel run): the full EQ stays across the top (y 300, mono ≥ 56); count rows build under it (y 520–880, left-aligned at x 96, mono 52): row 'Fe: 3 = 1 + 2' builds '3' on cue 'تلات', '1' on cue 'واحدة', '2' on cue 'واتنين'; the Fe atoms in the EQ pulse gold.","tts_text":"نعد الحديد: تلات ذرات، واحدة في الـ iron اتنين، واتنين في الـ iron تلاتة.","screen_text":"Iron: 3 = 1 (FeSO₄) + 2 (Fe₂(SO₄)₃)"},{"id":"s6l9","visual":"[CORE] FB count row 'S: 8 = 1 + 3 + 4' builds on cues 'تمانية', 'وتلاتة', 'وأربعة'; the S atoms in the EQ pulse.","tts_text":"والـ sulphur تمانية: واحد، وتلاتة، وأربعة في الغاز.","screen_text":"Sulphur: 8 = 1 + 3 + 4"},{"id":"s6l10","visual":"[CORE] FB count row 'O: 32 = 4 + 12 + 8 + 8' builds on cue 'وتلاتين'; tag 'all in compounds' on cue 'compounds'; a ghost 'O₂(g)' with a coral strike on cue 'ومفيش'.","tts_text":"والـ oxygen اتنين وتلاتين، كله جوه compounds، ومفيش oxygen غاز طالع.","screen_text":"Oxygen: 32 = 4 + 12 + 8 + 8, all bound in compounds"},{"id":"s6l11","visual":"[CORE] FB count row 'H: 16 → 8H₂O' on cue 'ستاشر'; the two 8s of the EQ pulse gold on cue 'تمانية'; 'balanced ✓' tag at line end.","tts_text":"والـ hydrogen ستاشر ذرة، راحوا كلهم في تمانية جزيء مية.","screen_text":"Hydrogen: 16 H → 8H₂O"},{"id":"s6l12","visual":"[CORE] TP refutation (G40, misconception #2): ghost 'Fe₂(SO₄)₃ only' + small YK.wrongMark on cue 'بس' (< 2 s); both products glow on cue 'الاتنين'.","tts_text":"ومش iron تلاتة sulphate بس: الاتنين بيطلعوا مع بعض.","screen_text":"Only iron (III) sulphate ✗ both sulphates form"},{"id":"s6l13","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: the book's equation scaled to 6 Fe; not in the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: six grey Fe discs on cue 'ستة' beside the dimmed EQ; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"ستة iron مع الـ sulphuric acid ده: يطلع كام sulphur dioxide؟ وقّفوا وفكّروا.","screen_text":"6 Fe atoms, same reaction: how many SO₂?","pause_after_s":3},{"id":"s6l14","visual":"[CORE] TP: '× 2' over the EQ on cue 'بتتضاعف'; '4SO₂ → 8SO₂' on cue 'فالأربعة' + YK.rightMark.","tts_text":"تمانية: كل حاجة بتتضاعف، فالأربعة بقوا تمانية.","screen_text":"8SO₂ ✓ everything doubles"},{"id":"s6l15","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron with hot concentrated sulphuric acid', line:'Iron (II) sulphate + iron (III) sulphate + sulphur dioxide + water · no hydrogen', formula:'3Fe + 8H₂SO₄ → FeSO₄ + Fe₂(SO₄)₃ + 4SO₂ + 8H₂O', pulse:[{word:'dioxide', at:YK.cue('s6l15','sulphur')}]}).","tts_text":"الخلاصة: الـ concentrated السخن بيدّي الاتنين sulphate، و sulphur dioxide، من غير hydrogen خالص.","screen_text":"Hot concentrated H₂SO₄ → both sulphates + SO₂ + water · no hydrogen"},{"id":"s6l16","visual":"[CORE] SO-WHAT · FB: the c2 nitric acid flask slides in on cue 'nitric'. Segment chip out; m2 follows.","tts_text":"فاضل acid أخير غريب: الـ nitric acid بتاعنا.","screen_text":"One last acid, and a strange one: nitric acid","pause_after_s":1},{"id":"m2l1","visual":"[CORE] MID-EPISODE RECAP 2 (after Parts 4-6) · FB. The m1 flow returns with its 3 nodes dimmed; node 4 'Dilute acids' (sub 'iron (II) salt + H₂') lit on cue 'dilute'.","tts_text":"نلم تاني: الـ dilute acids تدّي iron اتنين salt، و hydrogen معاه.","screen_text":"Dilute acids → iron (II) salt + hydrogen"},{"id":"m2l2","visual":"[CORE] Flow: node 4 sub-tag 'H₂ reduces +3 → +2' on cue 'reduction'.","tts_text":"عشان الـ hydrogen الطالع بيعمل reduction للـ iron تلاتة.","screen_text":"The hydrogen reduces iron (III) to iron (II)"},{"id":"m2l3","visual":"[CORE] Flow: node 5 'Hot conc. H₂SO₄' (sub 'FeSO₄ + Fe₂(SO₄)₃ + SO₂') lit on cue 'concentrated'. In the pause: camera move into the PART 7 card.","tts_text":"والـ concentrated السخن بيدّي الاتنين sulphate، ومعاهم sulphur dioxide كمان.","screen_text":"Hot concentrated H₂SO₄ → both sulphates + SO₂","pause_after_s":2.5},{"id":"s7l1","style":"curious","visual":"PART 7/7 · fe.passivity · objective: Explain the passivity of iron in concentrated nitric acid. · [CORE] Segment card in m2l3's 2.5 s pause (camera move in, no fade): YK.partCard({num:7, of:7, title:'Passivity of iron', objective:'Explain the passivity of iron in concentrated nitric acid', at: cueEnd(previous line)+0.1, collapse: YK.cue('s7l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Passivity of iron', never cut) on line start, chip kept to the micro-recap. Line: FB the c2 split returns (dilute flask fizzing left, nitric acid flask still right) on cue 'nitric'; '?' on cue 'صح'. RE-HOOK.","tts_text":"المفروض الـ concentrated nitric acid ياكل الحديد بسرعة، صح؟","screen_text":"Concentrated nitric acid should eat iron fast… right?"},{"id":"s7l2","visual":"PREREQ te.chromium-oxide-layer (in-book, Unit 2; E2d callback ≤ 8 s adding only 'an oxide layer protects') · TP. Prereq YK.chip (link icon) 'Why chromium resists the effect of atmosphere'. Stage, same model as video-short-te.chromium-oxide-layer: YK.oxideSkin({metal:'Cr', porous:false, acidLabel:'O2'}), air particles bounce off on cue 'بتحميه'; the next line swaps metal:'Cr' → 'Fe' in the same position (E11). Prereq chip out at line end.","tts_text":"فاكرين الـ chromium؟ طبقة oxide رقيقة بتحميه من الجو.","screen_text":"Chromium: a thin oxide layer protects it"},{"id":"s7l3","visual":"[CORE] FB LAYER: the iron surface cross-section; the dark oxide film grows across it on cue 'بيكوّن'; label 'thin layer of oxide' on cue 'رقيقة'.","tts_text":"هنا الـ acid بيكوّن طبقة oxide رقيقة على سطح الحديد.","screen_text":"The acid forms a thin layer of oxide on the iron"},{"id":"s7l4","visual":"[CORE] FB LAYER: acid particles bounce off the film on cue 'بتحمي'; tag 'protects from further reaction' on cue 'تفاعل' (book p.21).","tts_text":"والطبقة دي بتحمي المعدن من أي تفاعل بعد كده.","screen_text":"The layer protects the metal from further reaction"},{"id":"s7l5","visual":"[CORE] TP DEFINITION CARD (E3a, the part's one card) YK.termCard({term:'Passivity', def:'Concentrated nitric acid causes passivity of iron due to the formation of a thin layer of oxide which protects the metal from further reaction.', keys:['thin layer of oxide','further reaction']}) on cue 'passivity' (NEW TERM 1/3); tag 'passive' on the iron on cue 'passive'.","tts_text":"الحالة دي اسمها passivity، والحديد بيبقى passive خالص.","screen_text":"Passivity of iron"},{"id":"s7l6","visual":"[CORE] TP refutation (G40, fe.passivity misconception #1): 'dissolves iron quickly' + small YK.wrongMark on cue 'مش' (< 2 s); the c2 flask's stopped bubbles on cue 'بيوقّف'.","tts_text":"يعني مش بيدوّبه بسرعة، بالعكس، بيوقّف التفاعل.","screen_text":"Dissolves iron quickly ✗ it stops the reaction"},{"id":"s7l7","visual":"[CORE] FB split (E7, first-mentioned left): left the dilute flask fizzing on cue 'بيدوّب'; right the nitric acid flask still, its nail wrapped in the dark film, on cue 'بيوقّفه'; gold tag 'opposite!' on cue 'عكس'.","tts_text":"الـ dilute acid بيدوّب الحديد، والـ concentrated nitric acid بيوقّفه… عكس المتوقع.","screen_text":"Dilute acid dissolves iron · concentrated nitric acid stops it"},{"id":"s7l8","visual":"[CORE] TP refutation (misconception #2 'passivity is permanent'): tag 'not permanent' on cue 'دايمة'; stage: the film flickers.","tts_text":"بس الـ passivity دي مش دايمة.","screen_text":"Passivity is not permanent"},{"id":"s7l9","visual":"[CORE] E2c-style book list p.21 (two items, one per line): TP 'Removed by:' + '1. abrasion' on cue 'abrasion' (NEW TERM 2/3); stage LAYER: sandpaper strokes scrape the film off on cue 'نحك'.","tts_text":"نشيل الطبقة بالـ abrasion، يعني نحك السطح.","screen_text":"Removed by: 1. abrasion"},{"id":"s7l10","visual":"[CORE] List item '2. dilute hydrochloric acid' on cue 'dilute'; stage LAYER: a drop dissolves the film on cue 'فيدوب'.","tts_text":"أو نستخدم dilute hydrochloric acid، فيدوب الطبقة.","screen_text":"2. dilute hydrochloric acid"},{"id":"s7l11","visual":"[CORE] FB: the bare iron fizzes in dilute acid again on cue 'يتفاعل'.","tts_text":"والحديد اللي تحتها يرجع يتفاعل عادي.","screen_text":"Fresh iron → it reacts again"},{"id":"s7l12","visual":"[CORE] FB FLASK of dilute HCl (tag 'dilute HCl'): bubbles stream from the bare nail on cue 'hydrogen'; small EQ reminder 'Fe + 2HCl → FeCl₂ + H₂' (from Part 4) on cue 'بيدوّب'.","tts_text":"ولما الطبقة تروح، الـ dilute acid بيدوّب الحديد، ويطلّع hydrogen زي الأول.","screen_text":"In dilute acid: iron dissolves again, hydrogen forms"},{"id":"s7l13","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: an iron storage tank; not in the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: a cutaway iron tank with the acid inside on cue 'خزان'; the inner wall zooms in on cue 'الجدار'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"خزان حديد فيه concentrated nitric acid. الـ acid هيفضل ياكل الجدار؟ وقّفوا وفكّروا.","screen_text":"Concentrated nitric acid is stored in an iron tank. Does it keep eating the wall?","pause_after_s":3},{"id":"s7l14","visual":"[CORE] FB LAYER on the tank wall: the film forms on cue 'طبقة'; acid particles bounce on cue 'بتحميه'; YK.rightMark + tag 'passivity' on cue 'passivity'.","tts_text":"لأ: طبقة الـ oxide الرقيقة بتحميه، ده الـ passivity بعينه.","screen_text":"No ✓ the thin oxide layer protects it: passivity"},{"id":"s7l15","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Passivity of iron', line:'A thin layer of oxide protects the metal · removed by abrasion or dilute HCl', pulse:[{word:'passivity', at:YK.cue('s7l15','passivity')}, {word:'abrasion', at:YK.cue('s7l15','abrasion')}]}).","tts_text":"الخلاصة: الـ passivity طبقة oxide بتحمي الحديد، والـ abrasion بيشيلها.","screen_text":"Passivity: a thin oxide layer protects iron · removed by abrasion"},{"id":"s7l16","visual":"[CORE] SO-WHAT · FB: the parts' icons shrink into a row at the bottom on cue 'نلم'. Segment chip out.","tts_text":"يلا نلم الحلقة كلها في سلسلة واحدة.","screen_text":"Now the whole unit in one chain","pause_after_s":1},{"id":"z1","visual":"[CORE] CLOSING SUMMARY · FB. YK.flow({rtl:false}) LTR in book order, nodes ≥ 32 px: node 1 'Pure iron: soft' on cue 'طري', sub 'steels, alloys' on cue 'alloys'.","tts_text":"الحديد النقي طري، فبنستعمل الـ steel والـ alloys بداله.","screen_text":"Pure iron: relatively soft → steels and alloys"},{"id":"z2","visual":"[CORE] FB flow: node 2 'Air / water vapour → Fe₃O₄' on cue 'magnetic'.","tts_text":"والهوا وبخار المية على الحديد الأحمر، يدّوا الـ magnetic iron oxide كمان.","screen_text":"Air / water vapour → magnetic iron oxide"},{"id":"z3","visual":"[CORE] FB flow: node 3 'Cl₂ → +3 · S → +2' on cue 'chlorine'; the OX-LADDER mini icon fills on cue 'تلاتة'.","tts_text":"الـ chlorine الـ oxidizing agent القوي يدّي iron تلاتة، والـ sulphur iron اتنين.","screen_text":"Strong oxidizing agent (chlorine) → iron (III) · sulphur → iron (II)"},{"id":"z4","visual":"[CORE] FB flow: node 4 'Dilute acids → iron (II) + H₂' on cue 'dilute', sub 'H₂ reduces iron (III)' on cue 'reduction'.","tts_text":"والـ dilute acids تدّي iron اتنين، عشان الـ hydrogen بيعمل reduction للتلاتة.","screen_text":"Dilute acids → iron (II): the hydrogen reduces iron (III)"},{"id":"z5","visual":"[CORE] FB flow: node 5 'Hot conc. H₂SO₄ → +2 and +3 + SO₂' on cue 'concentrated'.","tts_text":"والـ concentrated السخن يدّي الـ sulphate الاتنين، مع sulphur dioxide طالع.","screen_text":"Hot concentrated H₂SO₄ → both sulphates + SO₂"},{"id":"z6","visual":"[CORE] FB flow: node 6 'Conc. HNO₃ → passivity' on cue 'passivity'.","tts_text":"وأخيرًا الـ concentrated nitric acid بيعمل passivity، ويوقّف التفاعل.","screen_text":"Concentrated nitric acid → passivity"},{"id":"z7","visual":"[CORE] BIG QUESTION ANSWERED · FB: the cold-open gold tag 'What decides what iron becomes?' returns centre; the flow's nodes 3-6 pulse on cue 'الشريك'; tag 'partner + conditions ✓' on cue 'والظروف'.","tts_text":"وإجابة سؤالنا: اللي بيقرر هو الشريك، والظروف: مخفف ولا مركز، سخن ولا لأ.","screen_text":"What decides? ✓ the partner and the conditions"},{"id":"z8","visual":"[CORE] RECALL 1/3 (Part 3; book Evaluation Q1.1 p.25 wording) · YK.predictCard({kind:'RECALL 1 OF 3', q: screen_text}) in the text panel; stage: iron filings + sulphur dish; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"سؤال الكتاب: الحديد مع الـ sulphur بيدّي إيه؟ وقّفوا وفكّروا.","screen_text":"The reaction of iron and sulphur gives …","pause_after_s":3},{"id":"z9","visual":"[CORE] FB (breaks the text-panel run): iron filings + sulphur in a dish over a flame form a solid product; YK.answerSlot 'FeS ✓ iron (II) sulphide' + YK.rightMark on cue 'sulphide'; OX-LADDER mini token at '+2'.","tts_text":"الإجابة: iron اتنين sulphide، لأن الـ sulphur أضعف.","screen_text":"FeS ✓ iron (II) sulphide"},{"id":"z10","visual":"[CORE] RECALL 2/3 (Parts 4-5; book Evaluation Q7.7 p.27 wording) · YK.predictCard({kind:'RECALL 2 OF 3', q: screen_text}) in the text panel; stage: the FLASK fizzing; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"علّل: الحديد مع الـ dilute acids بيدّي iron اتنين salts، مش تلاتة. وقّفوا وفكّروا.","screen_text":"Give reason: iron reacts with dilute acids to produce iron (II) salts, not iron (III) salts","pause_after_s":3},{"id":"z11","visual":"[CORE] FB close-up (breaks the text-panel run): inside the dilute-acid FLASK an 'e⁻' passes from a H₂ bubble to a '+3' token, which steps to '+2' on cue 'تلاتة'; YK.answerSlot 'the produced hydrogen reduces any iron (III) formed ✓' + YK.rightMark on cue 'reduction'.","tts_text":"لأن الـ hydrogen الناتج بيعمل reduction لأي iron تلاتة بيتكوّن.","screen_text":"✓ the produced hydrogen reduces any iron (III) formed"},{"id":"z12","visual":"[CORE] RECALL 3/3 (Part 6; NEW case: the pop test; not in the unit's lessons or questions) · YK.predictCard({kind:'RECALL 3 OF 3', q: screen_text}) in the text panel; stage: a burning splint near the flask mouth on cue 'الشعلة'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"حديد في الـ concentrated sulphuric acid السخن: الغاز هيفرقع مع الشعلة؟ وقّفوا وفكّروا.","screen_text":"Iron + hot concentrated H₂SO₄: does the gas pop with a flame?","pause_after_s":3},{"id":"z13","visual":"[CORE] FB: the splint meets the SO₂ wisps: no pop, YK.rightMark on cue 'لأ'; label 'SO₂, not H₂' on cue 'sulphur'.","tts_text":"لأ: ده sulphur dioxide، مش hydrogen خالص.","screen_text":"No ✓ the gas is SO₂, not hydrogen"},{"id":"z14","visual":"[TRIM-IF-OVER 15:00] TEASER (labelled last line only) · FB; label 'Next episode:' (Cairo 800 40, textDim) + 'Iron oxides' (Cairo 1000 64) on cue 'oxides'. No subscribe. 0.8 s tail.","tts_text":"الحلقة الجاية: الـ oxides بتاعة الحديد، التلاتة.","screen_text":"Next episode: Iron oxides"}],"logline":"The same iron fizzes in dilute acid, stops dead in concentrated nitric acid, and becomes iron (III) with chlorine but iron (II) with sulphur: what decides? Seven parts in the book's order (pp.20-21): the physical properties of pure iron (relatively soft, malleable, ductile, magnetic, 1538 °C, 7.87 g/cm³; why steels and alloys are used), red hot iron with air and with water vapour (magnetic iron oxide), iron with chlorine (FeCl₃) and sulphur (FeS), iron with dilute acids (iron (II) salts + hydrogen) and the book's reason (the produced hydrogen reduces iron (III)), hot concentrated sulphuric acid (both sulphates, sulphur dioxide, water) and the passivity of iron in concentrated nitric 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حديد في dilute acid بيفور وبيدوب\nقدام عينك\nنفس المسمار في concentrated nitric acid\nوالتفاعل بيقف خالص\nالـ dilute يعني acid قليل في مية كتير والـ\nconcentrated العكس\nومع الـ chlorine يبقى iron تلاتة ومع الـ\nsulphur iron اتنين بس\nنفس الحديد ونواتج مختلفة مين اللي بيقرر\nالحلقة دي عن الـ properties بتاعة الحديد\nالفيزيائية والكيميائية\nالحديد النقي ينفع نبني بيه كوبري\nفاكرين الـ malleable بيتطرق ألواح والـ\nductile بيتسحب أسلاك\nالكتاب بيقول الحديد النقي طري نسبيًا والـ\nhardness بتاعته قليلة\nوهو malleable و ductile يعني بيتشكل بسهولة\nوكمان ليه magnetic properties والمغناطيس\nبيشده\nوبيدوب عند ألف خمسمية تمانية وتلاتين درجة\nوالـ density بتاعته سبعة فاصل سبعة وتمانين\nجرام لكل سنتيمتر مكعب\nناس كتير فاكرة إن الحديد النقي ناشف جدًا\nلأ ده طري\nوعشان هو طري الحديد النقي ملوش أهمية في\nالصناعة\nوالـ physical properties بتاعته بتعتمد على\nنقاوته وعلى نوع الـ impurities اللي فيه\nفبنعمل منه أنواع steel و alloys كتير\nعينة حديد بتدوب عند ألف ربعمية وخمسين درجة\nدي حديد نقي وقّفوا وفكّروا\nلأ مش نقي الـ melting point من الـ\nphysical properties وبيعتمد على النقاوة\nالخلاصة الحديد النقي طري و malleable و\nductile وليه magnetic properties كمان\nده الحديد من بره طب كيميائيًا بيتفاعل إزاي\nنسخّن الحديد لحد ما يحمر ونعدّي عليه هوا\nناشف يطلع إيه\nفاكرين الـ oxidation إن المادة تاخد oxygen\nوالـ reduction إنها تخسره\nالحديد وهو أحمر من السخونية مع oxygen أو\nهوا ناشف\nبيدّي الـ magnetic iron oxide أسود وبيتشد\nللمغناطيس\nالمعادلة تلاتة iron مع اتنين جزيء oxygen\nيدّوا جزيء واحد منه\nالحديد هنا خد oxygen يعني ده oxidation\nللحديد\nولو بدل الهوا عدّينا بخار مَيّة على حديد\nخمسمية درجة\nيطلع نفس الـ magnetic iron oxide ومعاه\nhydrogen غاز طالع\nتلاتة iron مع أربعة بخار مَيّة يدّوا الـ\noxide وأربعة hydrogen طالعين\nوخدوا بالكم مش بيطلع hydroxide ولا iron\nتلاتة oxide هنا\nبخار المية خسر الـ oxygen بتاعه فحصله\nreduction وطلع hydrogen في الآخر\nسلك مواعين حديد بيولّع في oxygen نقي\nالناتج الأسود هيتشد للمغناطيس وقّفوا\nوفكّروا\nأيوه ده الـ magnetic iron oxide زي ما\nالاسم بيقول\nالخلاصة الهوا أو بخار المية على حديد أحمر\nيدّوا الـ magnetic iron oxide كده\nطب ولو الشريك مفيهوش oxygen خالص\nالـ chlorine والـ sulphur مفيهمش oxygen\nالحديد هيتفاعل معاهم برضه\nفاكرين الـ oxidation state الـ chlorine\nسالب واحد والـ sulphur سالب اتنين\nالحديد مع الـ chlorine بالتسخين بيدّي iron\nتلاتة chloride على طول\nاتنين iron مع تلاتة chlorine يدّوا اتنين\nمن الـ chloride ده\nتلات ذرات chlorine كل واحدة سالب واحد يبقى\nالحديد تلاتة موجب\nأما مع الـ sulphur بالتسخين بيدّي iron\nاتنين sulphide بس\nذرة iron مع ذرة sulphur والـ sulphur سالب\nاتنين فالحديد اتنين موجب\nليه الفرق الـ chlorine ده oxidizing agent\nقوي والـ sulphur أضعف منه\nالأقوى بيوصّل الحديد لتلاتة موجب والأضعف\nبيوقّفه عند اتنين\nوفي ناس بتكتب sulphate هنا لأ مفيش oxygen\nأصلًا فمفيش sulphate خالص\nأربع ذرات iron مع الـ chlorine محتاجين كام\nchlorine ويطلع كام chloride وقّفوا وفكّروا\nستة chlorine ويطلع أربعة iron تلاتة\nchloride يعني المعادلة متضاعفة\nالخلاصة الـ chlorine يدّي iron تلاتة والـ\nsulphur يدّي iron اتنين\nقبل الـ acids نلم اللي فات بسرعة\nنلم اللي فات الحديد النقي طري وخواصه\nبتعتمد على نقاوته\nوالهوا أو بخار المية على الحديد الأحمر\nبيدّوا الـ magnetic iron oxide كمان\nوالـ chlorine يدّي iron تلاتة والـ sulphur\nيدّي iron اتنين\nالحديد في dilute acid هيدّي iron اتنين ولا\niron تلاتة\nفاكرين metal فوق الـ hydrogen مع dilute\nacid يدّي salt والـ hydrogen بيطلع\nالحديد بيدوب في الـ mineral acids الـ\ndilute منها\nويدّي iron اتنين salts مش iron تلاتة\nمع الـ dilute sulphuric acid يطلع iron\nاتنين sulphate والـ hydrogen بيفور\nومع الـ hydrochloric acid الـ dilute iron\nاتنين chloride و hydrogen برضه\nليه اتنين hydrochloric الحديد اتنين موجب\nمحتاج ذرتين chlorine معاه\nوناس فاكرة إن الحديد مش بيتفاعل مع dilute\nacids لأ ده بيفور\nذرتين iron في الـ hydrochloric acid كام\nacid وكام hydrogen وقّفوا وفكّروا\nأربعة acid واتنين hydrogen ومعاهم اتنين من\nالـ chloride بتاعنا\nالخلاصة الحديد مع الـ dilute acids يدّي\niron اتنين salt و hydrogen كمان\nطب ليه مش iron تلاتة زي الـ chlorine\nبالظبط\nالـ hydrochloric acid فيه chlorine أمّال\nليه iron اتنين chloride مش تلاتة\nفاكرين الـ reduction إن المادة تاخد\nelectrons والـ reducing agent هو اللي\nبيدّيها\nالكتاب بيقول أي iron تلاتة salts بتتكوّن\nالـ hydrogen الطالع بيعمل لها reduction\nفورًا\nلأن الـ hydrogen بيطلع في نفس الدورق جنب\nالحديد بالظبط\nفالـ iron تلاتة ياخد electron ويرجع iron\nاتنين تاني\nيعني الـ hydrogen هنا هو الـ reducing\nagent بتاعنا\nأما الـ chlorine الغاز مفيهوش hydrogen\nفالـ iron تلاتة بيفضل كده\nفاللي يقول إن الـ hydrochloric acid زي الـ\nchlorine بالظبط غلطان\nطب الحديد في dilute hydrobromic acid المرة\nدي\nهيدّي iron اتنين bromide ولا iron تلاتة\nbromide وقّفوا وفكّروا\nالصح iron اتنين bromide الـ hydrogen اللي\nبيطلع بيعمل reduction لأي iron تلاتة\nالخلاصة iron اتنين مش تلاتة عشان الـ\nhydrogen الطالع بيعمل reduction على طول\nطب ولو الـ acid ده concentrated وسخن\nالحكاية بتتقلب\nالـ sulphuric acid لما يبقى concentrated\nوسخن هيطلع hydrogen تاني\nوالـ concentrated عكس الـ dilute acid كتير\nومية قليلة\nبيطلع iron اتنين sulphate و iron تلاتة\nsulphate مع بعض\nومعاهم sulphur dioxide غاز ومية كمان\nالمعادلة تلاتة iron مع تمانية sulphuric\nacid الـ concentrated السخن\nتدّي sulphate من كل نوع وأربعة sulphur\ndioxide وتمانية جزيء مية\nيعني مفيش hydrogen هنا الغاز هو الـ\nsulphur dioxide نفسه\nنعد الحديد تلات ذرات واحدة في الـ iron\nاتنين واتنين في الـ iron تلاتة\nوالـ sulphur تمانية واحد وتلاتة وأربعة في\nالغاز\nوالـ oxygen اتنين وتلاتين كله جوه\ncompounds ومفيش oxygen غاز طالع\nوالـ hydrogen ستاشر ذرة راحوا كلهم في\nتمانية جزيء مية\nومش iron تلاتة sulphate بس الاتنين بيطلعوا\nمع بعض\nستة iron مع الـ sulphuric acid ده يطلع كام\nsulphur dioxide وقّفوا وفكّروا\nتمانية كل حاجة بتتضاعف فالأربعة بقوا\nتمانية\nالخلاصة الـ concentrated السخن بيدّي\nالاتنين sulphate و sulphur dioxide من غير\nhydrogen خالص\nفاضل acid أخير غريب الـ nitric acid بتاعنا\nنلم تاني الـ dilute acids تدّي iron اتنين\nsalt و hydrogen معاه\nعشان الـ hydrogen الطالع بيعمل reduction\nللـ iron تلاتة\nوالـ concentrated السخن بيدّي الاتنين\nsulphate ومعاهم sulphur dioxide كمان\nالمفروض الـ concentrated nitric acid ياكل\nالحديد بسرعة صح\nفاكرين الـ chromium طبقة oxide رقيقة\nبتحميه من الجو\nهنا الـ acid بيكوّن طبقة oxide رقيقة على\nسطح الحديد\nوالطبقة دي بتحمي المعدن من أي تفاعل بعد\nكده\nالحالة دي اسمها passivity والحديد بيبقى\npassive خالص\nيعني مش بيدوّبه بسرعة بالعكس بيوقّف\nالتفاعل\nالـ dilute acid بيدوّب الحديد والـ\nconcentrated nitric acid بيوقّفه عكس\nالمتوقع\nبس الـ passivity دي مش دايمة\nنشيل الطبقة بالـ abrasion يعني نحك السطح\nأو نستخدم dilute hydrochloric acid فيدوب\nالطبقة\nوالحديد اللي تحتها يرجع يتفاعل عادي\nولما الطبقة تروح الـ dilute acid بيدوّب\nالحديد ويطلّع hydrogen زي الأول\nخزان حديد فيه concentrated nitric acid الـ\nacid هيفضل ياكل الجدار وقّفوا وفكّروا\nلأ طبقة الـ oxide الرقيقة بتحميه ده الـ\npassivity بعينه\nالخلاصة الـ passivity طبقة oxide بتحمي\nالحديد والـ abrasion بيشيلها\nيلا نلم الحلقة كلها في سلسلة واحدة\nالحديد النقي طري فبنستعمل الـ steel والـ\nalloys بداله\nوالهوا وبخار المية على الحديد الأحمر يدّوا\nالـ magnetic iron oxide كمان\nالـ chlorine الـ oxidizing agent القوي\nيدّي iron تلاتة والـ sulphur iron اتنين\nوالـ dilute acids تدّي iron اتنين عشان الـ\nhydrogen بيعمل reduction للتلاتة\nوالـ concentrated السخن يدّي الـ sulphate\nالاتنين مع sulphur dioxide طالع\nوأخيرًا الـ concentrated nitric acid بيعمل\npassivity ويوقّف التفاعل\nوإجابة سؤالنا اللي بيقرر هو الشريك والظروف\nمخفف ولا مركز سخن ولا لأ\nسؤال الكتاب الحديد مع الـ sulphur بيدّي\nإيه وقّفوا وفكّروا\nالإجابة iron اتنين sulphide لأن الـ\nsulphur أضعف\nعلّل الحديد مع الـ dilute acids بيدّي iron\nاتنين salts مش تلاتة وقّفوا وفكّروا\nلأن الـ hydrogen الناتج بيعمل reduction\nلأي iron تلاتة بيتكوّن\nحديد في الـ concentrated sulphuric acid\nالسخن الغاز هيفرقع مع الشعلة وقّفوا\nوفكّروا\nلأ ده sulphur dioxide مش hydrogen خالص\nالحلقة الجاية الـ oxides بتاعة الحديد\nالتلاتة","countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"series_id":"chem-s3-en.ch1#sessions","episode_no":8,"episode_count":9,"lessons":["chem-s3-en.lesson-acid.metal-acid-reaction","chem-s3-en.lesson-chem.equation-balancing","chem-s3-en.lesson-fe.passivity","chem-s3-en.lesson-fe.physical-properties","chem-s3-en.lesson-fe.reaction-conc-sulfuric","chem-s3-en.lesson-fe.reaction-dilute-acids","chem-s3-en.lesson-fe.reactions-air-steam","chem-s3-en.lesson-fe.reactions-nonmetals","chem-s3-en.lesson-pt.oxidation-number","chem-s3-en.lesson-redox.basic","chem-s3-en.lesson-redox.electronic"]},{"id":"chem-s3-en.video-episode-fe-oxides","kind":"episode","version":1,"ord":501,"content_lang":"ar-EG","primary_concept_id":"fe.oxide-feo","concepts":[{"concept_id":"fe.oxide-feo","role":"primary"},{"concept_id":"fe.conversions","role":"secondary"},{"concept_id":"fe.oxide-fe2o3","role":"secondary"},{"concept_id":"fe.oxide-fe3o4","role":"secondary"}],"title":"Iron oxides","payload":{"title":"Iron oxides","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"16:9","format":"episode","script":[{"id":"c1","visual":"[CORE] COLD OPEN · FB. EPISODE MODELS (reuse in every part, same colour and position, E11): (a) OXIDE TRIO = three glass jars, left → right in book order: FeO black powder ('#2A2A2E', light outline), Fe₂O₃ red-brown powder ('#A0412D'), Fe₃O₄ black crystals with a small YK.magnet icon; formula labels YK.label JetBrains Mono ≥ 48 under each jar; a jar pulses when its oxide is named. (b) TUBE = a horizontal glass tube over a flame, a porcelain boat of solid in the middle; gas enters from the left (H₂ white arrows, CO grey arrows, air light-blue arrows) and leaves on the right (H₂O vapour white wisps, CO₂ grey); the solid changes to the product's colour and label on cue. (c) LADDER = a vertical thermometer on the stage's right with three lit rungs: '230–300 °C → Fe₃O₄', '400–700 °C → FeO', 'above 700 °C → Fe'. (d) OX-LADDER = rungs '+2 iron (II)' (teal '#2DE2E6') and '+3 iron (III)' (gold '#FFC94D'), the same model as the Properties of iron episode; neutral UI colours, never ion colours (G44). (e) BEAKER = YK.beaker for acid and alkali; the book's reddish brown Fe(OH)₃ precipitate settles as flakes. (f) EQ = YK.formula rows (≥ 48 px) in the text panel, built term by term on cue, condition over the arrow; ≤ 4 rows; counted atoms pulse gold. (g) MAP = YK.flow LTR conversion diagram; arrows labelled reagent + condition; up = oxidation (gold), down = reduction (teal). No references to shorts or other videos. Shot: a red-painted iron gate, a brush stroke of red pigment (frame 0 already on screen, drift ≤ 2%); the pigment zooms into the red Fe₂O₃ jar on cue 'iron', label 'iron (III) oxide' on cue 'تلاتة' (book p.23: used in red pigments in paints).  KIT MAP (lib/episode.js; template must also load lib/short.js, lib/chem.js, lib/matter.js, lib/lab.js, lib/flow.js): segment cards = YK.partCard (no 'sub' field: the part's angle lives in the objective); prereq chip = YK.prereqChip; PREDICT / QUICK CHECK / RECALL = YK.predictCard({kind, q: screen_text}) (think ring included, only the question during the silence) + YK.answerSlot for the answer; misconception rows = YK.mythLine (coral, smaller than the fix); micro-recaps = YK.takeaway centred (full-bleed) as written, pulse words are SINGLE words of the card (multi-word pulses never fire). Text-panel (TP) shots never more than 3 in a row: lines marked FB in this director pass break the runs. Colours only where the book gives them (FeO black, Fe₂O₃ red / red pigment, Fe₃O₄ black, Fe(OH)₃ reddish brown); every other solid or solution (iron (II) oxalate, FeSO₄, iron (III) salt solutions) stays kit-neutral and labelled (G37/G45).","tts_text":"الأحمر اللي في البويات ده iron تلاتة oxide كده.","screen_text":"Red paint pigment: iron (III) oxide"},{"id":"c2","visual":"[CORE] FB (shot change): a black magnetite rock pulls a compass needle / sticks to a magnet on cue 'بيشد'; it becomes the Fe₃O₄ jar, label 'magnetic iron oxide' on cue 'magnetic'.","tts_text":"وحجر أسود بيشد المغناطيس؟ ده الـ magnetic iron oxide برضه.","screen_text":"A black rock that grabs a magnet: magnetic iron oxide"},{"id":"c3","visual":"[CORE] FB: black powder pours into the FeO jar on cue 'وبودرة'; label 'iron (II) oxide' on cue 'اتنين'. The OXIDE TRIO stands complete.","tts_text":"وبودرة سودا ناعمة، اسمها iron اتنين oxide كده.","screen_text":"A black powder: iron (II) oxide"},{"id":"c4","visual":"PREREQ pt.oxidation-number [RECAP-PREREQ] (cold open, first use, one line ≤ 8 s, reference only) · FB. Prereq YK.chip (link icon) 'Oxidation state in compounds'. The '(II)' and '(III)' of the labels pulse on cue 'والرقم'; OX-LADDER rungs '+2' and '+3' light under them on cue 'state'. Prereq chip out at line end.","tts_text":"والرقم ده هو الـ oxidation state بتاع الحديد جوه كل واحد.","screen_text":"(II), (III): the oxidation state of iron"},{"id":"c5","style":"curious","visual":"[CORE] BIG QUESTION · FB. The trio dims to 30%; card centred (Cairo 1000 84) 'How do we make each oxide?' on line start, 'each' gold on cue 'كل'; held through the pause, then shrinks to a gold tag top-right (answered in z5).","tts_text":"نفس الحديد والـ oxygen… إزاي نطلّع كل oxide فيهم؟","screen_text":"How do we make each oxide?","pause_after_s":1},{"id":"t1","visual":"[CORE] TITLE CARD (≤ 4 s from line start). YK.titleCard({title:'Iron oxides', chip:'Unit 9', subtitle:'Chapter 1: Transition Elements'}) Cairo 1000 ≤ 120; 'oxides' gold on cue 'oxides'; parts row under it (YK.para Cairo 800 32, maxWidth 800): 1 FeO: preparation · 2 FeO: properties · 3 Iron(III) oxide Fe₂O₃ · 4 Magnetic iron oxide Fe₃O₄ · 5 Reaction diagrams: temperature · 6 Reaction diagrams: diagram (b). Then camera move (1.2 s, no fade) onto item 1, which grows into the PART 1 card.","tts_text":"الحلقة دي عن الـ iron oxides التلاتة، وإزاي بنحوّل واحد للتاني.","screen_text":"Iron oxides","pause_after_s":2.5},{"id":"s1l1","style":"curious","visual":"PART 1/6 · fe.oxide-feo · objective: Describe the two methods of preparing iron (II) oxide. · [CORE] Segment card in t1's 2.5 s pause (camera move in, no fade): YK.partCard({num:1, of:6, title:'Iron(II) oxide FeO', objective:'Describe the two methods of preparing iron (II) oxide', at: cueEnd(previous line)+0.1, collapse: YK.cue('s1l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron(II) oxide FeO', never cut) on line start, chip kept to the micro-recap. Line: FB TUBE with a kit-neutral solid (no colour claim) tagged 'iron (II) oxalate' on cue 'oxalate'; an air arrow with '?' at the tube mouth on cue 'هوا'. RE-HOOK.","tts_text":"عشان نعمل iron اتنين oxide، بنسخّن iron اتنين oxalate. في هوا ولا لأ؟","screen_text":"To make FeO: heat iron (II) oxalate. With air, or without?"},{"id":"s1l2","visual":"[CORE] FB TUBE: the tube ends close (stoppers) on cue 'مقفولة'; the air arrow crosses out on cue 'الهوا'; flame on; TP header 'Preparation (p.22)' + item '1. heating iron (II) oxalate in absence of air'.","tts_text":"نسخّنه في أنبوبة مقفولة، بعيد عن الهوا.","screen_text":"1. Heat iron (II) oxalate in absence of air"},{"id":"s1l3","visual":"[CORE] TP EQ row 1 builds: '(COO)₂Fe →Δ, in absence of air' on line start, 'FeO(s)' on cue 'oxide', '+ CO(g)' on cue 'monoxide', '+ CO₂(g)' on cue 'dioxide'; stage TUBE: the solid turns black on cue 'oxide'; two grey gas streams leave on cue 'carbon'.","tts_text":"بيدّي iron اتنين oxide، و carbon monoxide، و carbon dioxide كمان.","screen_text":"→ FeO(s) + CO(g) + CO₂(g)"},{"id":"s1l4","visual":"[CORE] FB: an air stream reaches hot FeO on cue 'oxidation'; the black powder reddens at the edge; tag 'easily oxidized in hot air' on cue 'بسهولة' (book p.22, property 2). Refutes fe.oxide-feo misconception #1 (heating the oxalate in air gives FeO).","tts_text":"ليه؟ لأن الـ oxide ده بيحصله oxidation بسهولة في الهوا السخن.","screen_text":"Why no air? FeO is easily oxidized in hot air"},{"id":"s1l5","visual":"[CORE] TP EQ row 2 builds: '4FeO(s)' on cue 'أربعة', '+ O₂(g)' on cue 'oxygen', '→Δ 2Fe₂O₃(s)' on cue 'يدّوا'; stage: the FeO jar turns red on cue 'أحمر'; OX-LADDER token +2 → +3.","tts_text":"أربعة iron اتنين oxide، مع oxygen، يدّوا iron تلاتة oxide أحمر.","screen_text":"4FeO(s) + O₂(g) →Δ 2Fe₂O₃(s): the black powder turns red"},{"id":"s1l6","visual":"PREREQ redox.basic [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Oxidation and reduction by oxygen'. Stage: an O atom leaves a grey atom on cue 'بتخسر' and joins an H₂ (white) on cue 'hydrogen' / a CO (grey) on cue 'carbon'. Prereq chip out at line end.","tts_text":"فاكرين الـ reduction؟ المادة بتخسر oxygen، و hydrogen أو carbon monoxide بياخدوه.","screen_text":"Reduction: loss of oxygen · taken by H₂ or CO"},{"id":"s1l7","visual":"[CORE] TP item '2. reduction of higher oxides' on cue 'higher' (NEW TERM 1/3); stage: the red Fe₂O₃ and black Fe₃O₄ jars step forward; atom-count chips 'Fe₂O₃: 3 O per 2 Fe', 'Fe₃O₄: 4 O per 3 Fe' vs 'FeO: 1 O per 1 Fe' on cue 'لكل' (counts from the formulas, no bars).","tts_text":"تاني طريقة: reduction للـ higher oxides، اللي فيها oxygen أكتر لكل حديد.","screen_text":"2. Reduction of higher oxides (Fe₂O₃, Fe₃O₄: more oxygen per iron)"},{"id":"s1l8","visual":"[CORE] FB TUBE: H₂ arrows on cue 'hydrogen', CO arrows on cue 'carbon'; LADDER appears with its middle rung '400–700 °C' lit on cue 'ربعمية'.","tts_text":"بنعمل لها reduction بالـ hydrogen أو الـ carbon monoxide، من ربعمية لسبعمية درجة.","screen_text":"by hydrogen or carbon monoxide at 400–700 °C"},{"id":"s1l9","visual":"[CORE] TP EQ row 3 builds: 'Fe₂O₃(s) + H₂(g)' on cue 'hydrogen', '→400–700 °C 2FeO(s)' on cue 'اتنين', '+ H₂O(v)' on cue 'وبخار' (book p.22); TUBE: red solid turns black.","tts_text":"من الـ iron تلاتة oxide مع hydrogen: اتنين iron اتنين oxide، وبخار مية.","screen_text":"Fe₂O₃ + H₂ →400–700 °C 2FeO + H₂O"},{"id":"s1l10","visual":"[CORE] FB close-up (breaks the text-panel run): TUBE full-bleed with black Fe₃O₄ in the boat, H₂ arrows; EQ row 4 as a formula strip (y 900, mono ≥ 56) builds: 'Fe₃O₄(s) + H₂(g) →400–700 °C' on cue 'magnetic', '3FeO(s)' on cue 'تلاتة', '+ H₂O(v)' on cue 'وبخار' (book p.22); the solid stays black (FeO is black too), water-vapour wisps leave right. All 4 rows back in the text panel on s1l11.","tts_text":"ونفس الكلام مع الـ magnetic iron oxide: تلاتة منه، وبخار مية.","screen_text":"Fe₃O₄ + H₂ →400–700 °C 3FeO + H₂O"},{"id":"s1l11","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: a nitrogen stream instead of a sealed tube; not in the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage TUBE with a nitrogen stream (pale arrows, tag 'N₂') on cue 'nitrogen'; two empty swatches 'black? red?' on cue 'سودا'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"نسخّن الـ oxalate في nitrogen بس. البودرة هتطلع سودا ولا حمرا؟ وقّفوا وفكّروا.","screen_text":"Iron (II) oxalate heated in nitrogen only (no air). Black or red powder?","pause_after_s":3},{"id":"s1l12","visual":"[CORE] TP answer 'Black ✓' + YK.rightMark on cue 'سودا'; stage: the boat's solid black, 'FeO' label on cue 'بيفضل'.","tts_text":"سودا: مفيش oxygen يأكسدها، فالـ oxide بيفضل زي ما هو.","screen_text":"Black ✓ no oxygen → FeO stays FeO"},{"id":"s1l13","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron(II) oxide FeO', line:'Heat iron (II) oxalate in absence of air · or reduce the higher oxides by H₂ or CO at 400–700 °C', pulse:[{word:'absence', at:YK.cue('s1l13','هوا')}, {word:'400–700', at:YK.cue('s1l13','ربعمية')}]}).","tts_text":"الخلاصة: الـ oxalate من غير هوا، أو الـ higher oxides من ربعمية لسبعمية.","screen_text":"FeO: iron (II) oxalate in absence of air · higher oxides + H₂ or CO at 400–700 °C"},{"id":"s1l14","visual":"[CORE] SO-WHAT · FB: the FeO jar slides next to an acid beaker on cue 'بيتصرف'. Segment chip stays (same concept); in the pause: camera move into the PART 2 card.","tts_text":"طيب عملنا الـ oxide ده… بيتصرف إزاي بقى؟","screen_text":"We have FeO. What does it do?","pause_after_s":2.5},{"id":"s2l1","style":"curious","visual":"PART 2/6 · fe.oxide-feo · objective: Describe the properties of iron (II) oxide. · [CORE] Segment card in s1l14's 2.5 s pause (camera move in, no fade): YK.partCard({num:2, of:6, title:'Iron(II) oxide FeO', objective:'Describe the properties of iron (II) oxide', at: cueEnd(previous line)+0.1, collapse: YK.cue('s2l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron(II) oxide FeO', never cut) on line start, chip kept to the micro-recap. Line: FB split (E7, first-mentioned left): left FeO powder drops into a BEAKER on cue 'dilute'; right an iron nail fizzing (H₂) as a reference on cue 'زي'. RE-HOOK.","tts_text":"الـ iron اتنين oxide في dilute acid… هيفور زي الحديد؟","screen_text":"FeO + dilute acid: will it fizz like iron?"},{"id":"s2l2","visual":"[CORE] TP properties list (book p.22) item 1 on cue 'سودا'; stage: a spoon of FeO in water stays as black grains on cue 'insoluble' (misconception #3 'FeO is red' refuted by the colour shot).","tts_text":"أول خاصية: بودرة سودا، و insoluble في المية.","screen_text":"1. Black powder, insoluble in water (not red)"},{"id":"s2l3","visual":"[CORE] FB close-up (breaks the text-panel run): hot FeO powder in an air stream, its edge reddens on cue 'oxidation'; the s1l5 equation as a strip (y 900); list item 2 'Easily oxidized in hot air' as a tag on cue 'بسهولة' (back in the text-panel list on s2l4).","tts_text":"تاني خاصية شفناها: بيحصله oxidation بسهولة في الهوا السخن.","screen_text":"2. Easily oxidized in hot air (that's why: absence of air)"},{"id":"s2l4","visual":"PREREQ chem.oxides [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Acidic and basic oxides'. Word equation 'basic oxide + acid → salt + water' builds on cues 'basic', 'salt', 'ومية'. Prereq chip out at line end.","tts_text":"فاكرين الـ basic oxide؟ مع الـ acid بيدّي salt ومية.","screen_text":"Basic oxide + acid → salt + water"},{"id":"s2l5","visual":"[CORE] TP item 3 (book p.22) on cue 'mineral'; stage: the FeO dissolves calmly, no bubbles, on cue 'salt'.","tts_text":"تالت خاصية: مع الـ mineral acids، يدّي iron اتنين salt ومية.","screen_text":"3. + mineral acids → iron (II) salts + water"},{"id":"s2l6","visual":"[CORE] TP EQ row 1 builds: 'FeO(s) + H₂SO₄(aq)' on cue 'sulphuric', '→dil. FeSO₄(aq)' on cue 'sulphate', '+ H₂O(l)' on cue 'ومية'; tag 'no gas' on cue 'غاز'.","tts_text":"مع الـ dilute sulphuric acid، يطلع iron اتنين sulphate، ومية، ومن غير غاز.","screen_text":"FeO(s) + H₂SO₄(aq) →dil. FeSO₄(aq) + H₂O(l)"},{"id":"s2l7","visual":"[CORE] FB OX-LADDER: the token sits on '+2' on cue 'كان' and stays there on cue 'وفضل'; tags '+2' under Fe in both formulas.","tts_text":"الحديد كان اتنين موجب في الـ oxide، وفضل اتنين موجب بعدها.","screen_text":"Iron +2 in FeO → still +2 in FeSO₄"},{"id":"s2l8","visual":"[CORE] TP refutation (G40, fe.oxide-feo misconception #2): ghost 'iron (III) salt' + small YK.wrongMark on cue 'فمش' (< 2 s); the token does not move on cue 'oxidation'.","tts_text":"فمش بيطلع iron تلاتة: مفيش حاجة حصلها oxidation هنا.","screen_text":"Iron (III)? ✗ nothing is oxidized"},{"id":"s2l9","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: FeO with HBr; not in the unit's lessons or questions). YK.predictCard({kind:'PREDICT', q: screen_text}) in the text panel; stage: BEAKER labelled 'HBr (dil.)' on cue 'hydrobromic'; skeleton 'FeO + 2HBr → ? + H₂O'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"الـ iron اتنين oxide مع dilute hydrobromic acid: يطلع إيه مع المية؟ وقّفوا وفكّروا.","screen_text":"FeO + dilute hydrobromic acid (HBr) → ? + H₂O","pause_after_s":3},{"id":"s2l10","visual":"[CORE] TP: '?' → 'FeBr₂' on cue 'bromide' + YK.rightMark; OX-LADDER token stays at '+2' on cue 'فضل'.","tts_text":"يطلع iron اتنين bromide، والحديد فضل اتنين موجب.","screen_text":"FeBr₂ ✓ iron (II) bromide: iron stays +2"},{"id":"s2l11","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron(II) oxide FeO', line:'Black powder · oxidized in hot air · + dilute acids → salt + water', formula:'FeO + H₂SO₄ → FeSO₄ + H₂O', pulse:[{word:'black', at:YK.cue('s2l11','سودا')}, {word:'salt', at:YK.cue('s2l11','salt')}]}).","tts_text":"الخلاصة: بودرة سودا، بيحصلها oxidation في الهوا، ومع الـ dilute acids تدّي salt ومية.","screen_text":"FeO: black · oxidized in hot air · + dilute acids → salt + water"},{"id":"s2l12","visual":"[CORE] SO-WHAT · FB: the red Fe₂O₃ jar glows on cue 'الأحمر'. Segment chip out; m1 follows.","tts_text":"نلم اللي فات، وبعدين الـ oxide الأحمر.","screen_text":"Quick recap, then the red oxide","pause_after_s":1},{"id":"m1l1","visual":"[CORE] MID-EPISODE RECAP 1 (after Parts 1-2) · FB. YK.flow({rtl:false, layout:'row', area:{x:96,y:380,w:1728,h:320}, node:{size:40}}); header 'So far: FeO' (Cairo 800 40). Node 1 'Iron (II) oxalate, no air' lit on cue 'oxalate'.","tts_text":"نلم اللي فات: iron اتنين oxide من الـ oxalate، بالتسخين من غير هوا.","screen_text":"FeO: heat iron (II) oxalate in absence of air"},{"id":"m1l2","visual":"[CORE] Flow: node 2 'Higher oxides + H₂/CO, 400–700 °C' lit on cue 'higher'.","tts_text":"أو من الـ higher oxides، بالـ hydrogen أو الـ carbon monoxide كمان.","screen_text":"or: higher oxides + H₂ or CO at 400–700 °C"},{"id":"m1l3","visual":"[CORE] Flow: node 3 'Black · hot air → Fe₂O₃ · dilute acid → FeSO₄ + H₂O' lit on cue 'أسود'. In the pause: camera move into the PART 3 card.","tts_text":"وهو أسود، بيحصله oxidation في الهوا السخن، ومع الـ dilute acid يدّي salt ومية.","screen_text":"Black · oxidized in hot air · + dilute acid → salt + water","pause_after_s":2.5},{"id":"s3l1","style":"curious","visual":"PART 3/6 · fe.oxide-fe2o3 · objective: Describe the preparation and properties of iron (III) oxide. · [CORE] Segment card in m1l3's 2.5 s pause (camera move in, no fade): YK.partCard({num:3, of:6, title:'Iron(III) oxide Fe₂O₃', objective:'Describe the preparation and properties of iron (III) oxide', at: cueEnd(previous line)+0.1, collapse: YK.cue('s3l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron(III) oxide Fe₂O₃', never cut) on line start, chip kept to the micro-recap. Line: FB the red Fe₂O₃ jar on a lab bench on cue 'الأحمر'; '?' on cue 'إزاي'. RE-HOOK.","tts_text":"الـ iron تلاتة oxide الأحمر… بنحضّره في المعمل إزاي؟","screen_text":"Fe₂O₃ is red. How do we make it in the lab?"},{"id":"s3l2","visual":"PREREQ chem.reaction-types [RECAP-PREREQ] (one line, ≤ 8 s, reference only) · TP. Prereq YK.chip (link icon) 'Types of chemical reactions'. Stage: two clear solutions mix and solid flakes appear and settle on cue 'بتظهر'. Prereq chip out at line end.","tts_text":"فاكرين الـ precipitate؟ مادة صلبة insoluble، بتظهر جوه المحلول.","screen_text":"Precipitate: an insoluble solid that forms in a solution"},{"id":"s3l3","visual":"[CORE] FB BEAKER: an alkali drips into a kit-neutral solution tagged 'iron (III) salt' (no solution colour, G45) on cue 'alkali'; reddish brown flakes fall on cue 'فينزل'; label 'iron (III) hydroxide' on cue 'hydroxide' (book pp.22-23).","tts_text":"نضيف alkali لمحلول iron تلاتة salt، فينزل hydroxide بني محمر.","screen_text":"1. Alkali + iron (III) salt solution → reddish brown Fe(OH)₃"},{"id":"s3l4","visual":"[CORE] TP EQ row 1 builds: 'FeCl₃(aq)' on cue 'chloride', '+ 3NH₄OH(aq)' on cue 'hydroxide', '→ Fe(OH)₃(s) + 3NH₄Cl(aq)' on cue 'يفضل'; stage: the reddish brown flakes settle; tag 'NH₄Cl stays dissolved' on cue 'دايب'.","tts_text":"مثال الكتاب: iron تلاتة chloride مع ammonium hydroxide… والـ ammonium chloride يفضل دايب.","screen_text":"FeCl₃(aq) + 3NH₄OH(aq) → Fe(OH)₃(s) + 3NH₄Cl(aq)"},{"id":"s3l5","visual":"[CORE] FB: the filtered flakes in a dish over a flame, thermometer 'above 200 °C' on cue 'ميتين'; they turn into red powder on cue 'فيطلع'; steam wisps on cue 'وبخار'.","tts_text":"نسخّن الـ hydroxide فوق ميتين درجة، فيطلع iron تلاتة oxide وبخار.","screen_text":"Heat Fe(OH)₃ above 200 °C → Fe₂O₃ + water vapour"},{"id":"s3l6","visual":"[CORE] TP EQ row 2 builds: '2Fe(OH)₃(s)' on cue 'اتنين', '→ Fe₂O₃(s)' on cue 'واحد', '+ 3H₂O(v)' on cue 'وتلات'.","tts_text":"اتنين hydroxide يدّوا oxide واحد، وتلات جزيئات بخار مية.","screen_text":"2Fe(OH)₃(s) →above 200 °C Fe₂O₃(s) + 3H₂O(v)"},{"id":"s3l7","visual":"[CORE] FB TUBE (no gas in): kit-neutral crystals tagged 'FeSO₄' (no colour claim, G45) in the boat on cue 'sulphate'; flame on cue 'نسخّن'.","tts_text":"الطريقة التانية: نسخّن iron اتنين sulphate لوحده.","screen_text":"2. Heating iron (II) sulphate"},{"id":"s3l8","visual":"[CORE] TP EQ row 3 builds: '2FeSO₄(s) →Δ Fe₂O₃(s)' on cue 'يدّوا', '+ SO₂(g)' on cue 'dioxide', '+ SO₃(g)' on cue 'trioxide' (book p.23); TUBE: the solid turns red, two grey gas streams leave.","tts_text":"اتنين sulphate يدّوا iron تلاتة oxide، و sulphur dioxide، و sulphur trioxide مع بعض.","screen_text":"2FeSO₄(s) →Δ Fe₂O₃(s) + SO₂(g) + SO₃(g)"},{"id":"s3l9","visual":"[CORE] FB OX-LADDER token +2 → +3 on cue 'لتلاتة'; two gas tags 'SO₂', 'SO₃' pulse on cue 'غازين'; ghost 'FeO' and 'SO₂ only' with small YK.wrongMarks (< 2 s; G40, fe.oxide-fe2o3 misconception #1).","tts_text":"الحديد طلع من اتنين لتلاتة، والـ sulphur خرج في غازين.","screen_text":"Iron +2 → +3 · sulphur leaves as two gases (not FeO ✗, not only SO₂ ✗)"},{"id":"s3l10","visual":"[CORE] FB: a red hematite rock beside the jar on cue 'hematite'; red powder in water stays as grains on cue 'insoluble'; the cold-open red gate returns on cue 'البويات' (book p.23).","tts_text":"وفي الطبيعة هو الـ hematite، و insoluble في المية، وبيلوّن البويات أحمر.","screen_text":"In nature: hematite · insoluble in water · red pigments in paints"},{"id":"s3l11","visual":"[CORE] TP book line (p.23) on cue 'mineral'; 'hot' and 'concentrated' gold on cues 'سخنة', 'concentrated'; stage: BEAKER over a flame.","tts_text":"ومع mineral acids سخنة و concentrated، يدّي iron تلاتة salt ومية.","screen_text":"+ hot concentrated mineral acids → iron (III) salts + water"},{"id":"s3l12","visual":"[CORE] TP EQ row 4 builds: 'Fe₂O₃(s) + 3H₂SO₄(aq)' on cue 'sulphuric', '→conc., Δ Fe₂(SO₄)₃(aq)' on cue 'sulphate', '+ 3H₂O(v)' on cue 'ومية'; OX-LADDER token stays at '+3'.","tts_text":"مع الـ sulphuric acid، بيطلع iron تلاتة sulphate، ومية، ومفيش غاز.","screen_text":"Fe₂O₃ + 3H₂SO₄ →conc., Δ Fe₂(SO₄)₃ + 3H₂O"},{"id":"s3l13","visual":"[CORE] FB split (E7, FeO left, identical layout): left 'FeO + dilute acid' on cue 'dilute'; right 'Fe₂O₃ + hot concentrated acid' on cue 'concentrated'; the conditions in gold (G40, fe.oxide-fe2o3 misconception #2: keep the book's conditions).","tts_text":"خدوا بالكم: الأسود مع الـ dilute، والأحمر مع الـ concentrated السخن.","screen_text":"FeO: dilute acids · Fe₂O₃: hot concentrated acids"},{"id":"s3l14","visual":"[CORE] PAUSE-AND-PREDICT (NEW case: iron (III) sulphate, the salt met in the Properties of iron episode, not the book's FeCl₃). YK.predictCard in the text panel; stage: an alkali drips into a kit-neutral solution tagged 'Fe₂(SO₄)₃(aq)' on cue 'sulphate', reddish brown flakes fall on cue 'alkali', the dish goes on a flame with a thermometer 'above 200 °C' on cue 'ميتين'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"طب iron تلاتة sulphate مع alkali، ونسخّن الـ precipitate فوق ميتين: الناتج؟ وقّفوا وفكّروا.","screen_text":"Iron (III) sulphate + alkali, then heat the precipitate above 200 °C. Product?","pause_after_s":3},{"id":"s3l15","visual":"[CORE] YK.answerSlot 'Fe₂O₃ ✓ any iron (III) salt + alkali → Fe(OH)₃ → Fe₂O₃' + YK.rightMark on cue 'oxide'; stage: the flakes turn to red powder on cue 'oxide', steam wisps.","tts_text":"الناتج iron تلاتة oxide: أي iron تلاتة salt مع alkali يدّي hydroxide، والتسخين يكمّل.","screen_text":"Fe₂O₃ ✓ iron (III) salt + alkali → Fe(OH)₃ → (above 200 °C) Fe₂O₃"},{"id":"s3l16","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron(III) oxide Fe₂O₃', line:'From Fe(OH)₃ above 200 °C, or by heating FeSO₄', pulse:[{word:'Fe(OH)₃', at:YK.cue('s3l16','hydroxide')}, {word:'FeSO₄', at:YK.cue('s3l16','sulphate')}]}).","tts_text":"الخلاصة: الـ iron تلاتة oxide من الـ hydroxide، أو بتسخين الـ sulphate كمان.","screen_text":"Fe₂O₃: from Fe(OH)₃ above 200 °C, or by heating FeSO₄"},{"id":"s3l17","visual":"[CORE] SO-WHAT · FB: the black FeO jar and the red Fe₂O₃ jar slide together into the Fe₃O₄ jar on cue 'الاتنين'. Segment chip out; in the pause: camera move into the PART 4 card.","tts_text":"فاضل oxide فيه الاتنين مع بعض… إزاي؟","screen_text":"One oxide holds both. How?","pause_after_s":2.5},{"id":"s4l1","style":"curious","visual":"PART 4/6 · fe.oxide-fe3o4 · objective: Explain why Fe₃O₄ is considered a mixed oxide. · [CORE] Segment card in s3l17's 2.5 s pause (camera move in, no fade): YK.partCard({num:4, of:6, title:'Magnetic iron oxide Fe₃O₄', objective:'Explain why Fe₃O₄ is considered a mixed oxide', at: cueEnd(previous line)+0.1, collapse: YK.cue('s4l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Magnetic iron oxide Fe₃O₄', never cut) on line start, chip kept to the micro-recap. Line: FB the Fe₃O₄ jar; a magnet pulls it on cue 'وبيشد'; the jar splits into a black half and a red half on cue 'oxides'. RE-HOOK.","tts_text":"أسود، وبيشد المغناطيس، وجواه اتنين oxides في نفس الوقت؟","screen_text":"Black, magnetic, and two oxides in one?"},{"id":"s4l2","visual":"[CORE] TP DEFINITION CARD (E3a, the part's one card) YK.termCard({term:'Mixed oxide', def:'Fe₃O₄ can be considered a mixed iron (II) and iron (III) oxide.', keys:['iron (II)','iron (III)']}) on cue 'mixed' (NEW TERM 1/3); OX-LADDER: one token on '+2' on cue 'اتنين', two on '+3' on cue 'تلاتة'.","tts_text":"ده بيتقال عليه mixed oxide: فيه iron اتنين و iron تلاتة.","screen_text":"Fe₃O₄: a mixed iron (II), iron (III) oxide"},{"id":"s4l3","visual":"[CORE] TP: 'FeO' on cue 'جمّعوا' + 'Fe₂O₃' on cue 'مع' = 'Fe₃O₄' on cue 'يطلع'; atom counts Fe 1+2 = 3, O 1+3 = 4 pulse gold.","tts_text":"جمّعوا iron اتنين oxide مع iron تلاتة oxide، يطلع هو بالظبط.","screen_text":"FeO + Fe₂O₃ = Fe₃O₄"},{"id":"s4l4","visual":"[CORE] FB: the c2 black rock returns, label 'magnetite' on cue 'magnetite' (book p.23).","tts_text":"وفي الطبيعة اسمه magnetite، الخام الأسود.","screen_text":"Known naturally as magnetite"},{"id":"s4l5","visual":"PREREQ fe.reactions-air-steam (in-book, Unit 8; E2d callback ≤ 8 s, adds only that this is a preparation of Fe₃O₄) · FB. Prereq YK.chip (link icon) 'Effect of air and water vapour'. Stage: a red hot iron bar in a TUBE, air arrows on cue 'هوا', steam on cue 'بخار'; its surface blackens on cue 'أحمر', label 'Fe₃O₄' above the tube (clear of the flame). Prereq chip out at line end.","tts_text":"أول طريقة: هوا سخن أو بخار مية على حديد أحمر.","screen_text":"Preparation 1: hot air or steam on red hot iron"},{"id":"s4l6","visual":"[CORE] FB TUBE: red Fe₂O₃ in the boat, CO arrows on cue 'carbon'; LADDER top rung '230–300 °C' lit on cue 'ميتين'.","tts_text":"التانية: reduction للـ iron تلاتة oxide بالـ carbon monoxide، من ميتين وتلاتين لتلتمية.","screen_text":"Preparation 2: reduction of Fe₂O₃ by CO at 230–300 °C"},{"id":"s4l7","visual":"[CORE] TP EQ row 1 builds: '3Fe₂O₃(s)' on cue 'تلاتة', '+ CO(g)' on cue 'carbon', '→230–300 °C 2Fe₃O₄(s) + CO₂(g)' on cue 'يدّوا' (book p.24); TUBE: red turns black.","tts_text":"تلاتة iron تلاتة oxide، مع carbon monoxide واحد، يدّوا اتنين منه.","screen_text":"3Fe₂O₃(s) + CO(g) →230–300 °C 2Fe₃O₄(s) + CO₂(g)"},{"id":"s4l8","visual":"[CORE] FB: iron filings jump to the Fe₃O₄ lump on cue 'magnet'; tag 'strong magnet' on cue 'قوي' (book p.24).","tts_text":"أول خاصية: ده magnet قوي، بيشد الحديد.","screen_text":"Property 1: a strong magnet"},{"id":"s4l9","visual":"[CORE] TP book line (p.24) on cue 'concentrated'; OX-LADDER: one token to '+2' on cue 'اتنين', one to '+3' on cue 'تلاتة'.","tts_text":"تاني خاصية: مع الـ concentrated acids السخنة، يدّي salts: iron اتنين و iron تلاتة.","screen_text":"Property 2: + hot concentrated acids → iron (II) and iron (III) salts"},{"id":"s4l10","visual":"[CORE] FB worked addition (s4l10–s4l12 are one full-bleed shot; memory pattern: no 4-line text-panel run): the split jar (black half / red half) at the top centre (y 160–480); three equation rows build full width under it (x 96–1824, mono ≥ 52, y 600 / 720 / 860): row 1 'FeO + H₂SO₄ → FeSO₄ + H₂O' on cue 'حتة', the black half glows.","tts_text":"حتة الـ iron اتنين oxide تدّي iron اتنين sulphate ومية.","screen_text":"FeO part: FeO + H₂SO₄ → FeSO₄ + H₂O"},{"id":"s4l11","visual":"[CORE] FB row 2 'Fe₂O₃ + 3H₂SO₄ → Fe₂(SO₄)₃ + 3H₂O' builds on cue 'وحتة'; the red half glows.","tts_text":"وحتة الـ iron تلاتة oxide تدّي iron تلاتة sulphate، وتلات جزيئات مية.","screen_text":"Fe₂O₃ part: Fe₂O₃ + 3H₂SO₄ → Fe₂(SO₄)₃ + 3H₂O"},{"id":"s4l12","visual":"[CORE] FB row 3 (sum line, gold rule above it) builds: 'Fe₃O₄ + 4H₂SO₄' with '1 + 3 = 4' over the 4 on cue 'أربعة', '→conc., Δ FeSO₄ + Fe₂(SO₄)₃ + 4H₂O' on cue 'وأربع'; the book's equation (p.24) is whole.","tts_text":"نجمعهم: واحد زائد تلاتة، يبقى أربعة sulphuric acid، وأربع جزيئات مية.","screen_text":"Add: Fe₃O₄ + 4H₂SO₄ →conc., Δ FeSO₄ + Fe₂(SO₄)₃ + 4H₂O"},{"id":"s4l13","visual":"[CORE] FB: the two salt formulas stamp 'proof' on cue 'الدليل'; the s4l2 card returns small with 'mixed oxide' gold on cue 'mixed'; ghost 'one salt' + small YK.wrongMark on cue 'عادي' (< 2 s; G40, fe.oxide-fe3o4 misconception #1).","tts_text":"طلعوا اتنين salts، وده الدليل إنه mixed oxide، مش oxide عادي.","screen_text":"Two salts → proof that it is a mixed oxide (not a single oxide ✗)"},{"id":"s4l14","visual":"[CORE] FB TUBE with air arrows: the black powder turns red on cue 'oxidation'; OX-LADDER: the '+2' token climbs to '+3' on cue 'لتلاتة' (book p.24).","tts_text":"تالت خاصية: بالتسخين في الهوا، حتة الـ iron اتنين بيحصلها oxidation لتلاتة.","screen_text":"Property 3: heated in air → Fe₂O₃ (its iron (II) part is oxidized)"},{"id":"s4l15","visual":"[CORE] TP EQ builds: '2Fe₃O₄(s)' on cue 'اتنين', '+ ½O₂(g)' on cue 'نص', '→Δ 3Fe₂O₃(s)' on cue 'يدّوا'.","tts_text":"اتنين منه، مع نص جزيء oxygen، يدّوا تلاتة من الأحمر.","screen_text":"2Fe₃O₄(s) + ½O₂(g) →Δ 3Fe₂O₃(s)"},{"id":"s4l16","visual":"[CORE] PAUSE-AND-PREDICT part 1 (NEW case: heat in air, then the acid; not in the unit's lessons or questions). FB (breaks the text-panel run): TUBE full-bleed with black Fe₃O₄ and air arrows on cue 'سخّنا'; it turns red; step tag '1. Fe₃O₄ heated in air' (the predict card opens on s4l17).","tts_text":"سخّنا الـ magnetic iron oxide في الهوا الأول،","screen_text":"Fe₃O₄ is heated in air first…"},{"id":"s4l17","visual":"[CORE] PAUSE-AND-PREDICT part 2 · TP step 2 '+ hot concentrated H₂SO₄' on cue 'concentrated'; question 'How many salts now?' on cue 'كام'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause. Stage: beaker of hot conc. H₂SO₄ with the red solid only; the OX-LADDER is withheld (no +3 state shown before the answer).","tts_text":"وبعدين حطيناه في concentrated acid سخن. كام salt؟ وقّفوا وفكّروا.","screen_text":"…then put in hot concentrated H₂SO₄. How many salts now?","pause_after_s":3},{"id":"s4l18","visual":"[CORE] TP answer 'One ✓ iron (III) sulphate' + YK.rightMark on cue 'واحد'; OX-LADDER fades in at line start (first shown here), all tokens at '+3' on cue 'بقى'.","tts_text":"واحد بس: iron تلاتة sulphate، لأنه بقى iron تلاتة oxide خلاص.","screen_text":"One ✓ only iron (III) sulphate: it is Fe₂O₃ now"},{"id":"s4l19","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Magnetic iron oxide Fe₃O₄', line:'A mixed oxide (magnetite) · strong magnet · two salts with hot concentrated acids · air → Fe₂O₃', pulse:[{word:'salts', at:YK.cue('s4l19','salts')}, {word:'mixed', at:YK.cue('s4l19','mixed')}]}).","tts_text":"الخلاصة: magnet قوي، وبيدّي اتنين salts، لأنه mixed oxide فعلًا.","screen_text":"Fe₃O₄: strong magnet · two salts → mixed oxide · air → Fe₂O₃"},{"id":"s4l20","visual":"[CORE] SO-WHAT · FB: the OXIDE TRIO with arrows sketching between the jars on cue 'الأسهم'. Segment chip out; m2 follows.","tts_text":"نلم الأول، وبعدين نرسم خريطة الأسهم.","screen_text":"Recap first, then the map of arrows","pause_after_s":1},{"id":"m2l1","visual":"[CORE] MID-EPISODE RECAP 2 (after Parts 3-4) · FB. YK.flow({rtl:false}) row of the OXIDE TRIO as nodes; node 'FeO' (sub 'oxalate, no air · 400–700 °C') lit on cue 'oxalate'.","tts_text":"نلم تاني: iron اتنين oxide من الـ oxalate، أو من ربعمية لسبعمية.","screen_text":"FeO: oxalate (no air) · H₂ or CO at 400–700 °C"},{"id":"m2l2","visual":"[CORE] Flow: node 'Fe₂O₃' (sub 'Fe(OH)₃ > 200 °C · heat FeSO₄') lit on cue 'hydroxide'.","tts_text":"و iron تلاتة oxide من الـ hydroxide، أو بتسخين الـ sulphate كمان.","screen_text":"Fe₂O₃: Fe(OH)₃ above 200 °C · heating FeSO₄"},{"id":"m2l3","visual":"[CORE] Flow: node 'Fe₃O₄' (sub 'red hot iron + air/steam · CO 230–300 °C') lit on cue 'magnetic'. In the pause: camera move into the PART 5 card.","tts_text":"وآخر واحد، الـ magnetic iron oxide، من حديد أحمر، أو على حرارة واطية.","screen_text":"Fe₃O₄: red hot iron + air or steam · CO at 230–300 °C","pause_after_s":2.5},{"id":"s5l1","style":"curious","visual":"PART 5/6 · fe.conversions · objective: Choose the reagent and condition for each step of a conversion diagram. · [CORE] Segment card in m2l3's 2.5 s pause (camera move in, no fade): YK.partCard({num:5, of:6, title:'Iron and its oxides: reaction diagrams', objective:'Choose the reagent and condition for each step of a conversion diagram', at: cueEnd(previous line)+0.1, collapse: YK.cue('s5l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron and its oxides: reaction diagrams', never cut) on line start, chip kept to the micro-recap. Line: FB three identical TUBES of red Fe₂O₃ with CO arrows on cue 'carbon'; three '?' products on cue 'مختلفة'. RE-HOOK.","tts_text":"نفس الـ carbon monoxide، ونفس الـ oxide… ونواتج مختلفة؟","screen_text":"Same gas, same oxide… different products?"},{"id":"s5l2","visual":"PREREQ fe.blast-furnace-reduction (in-book, Unit 6; E2d callback ≤ 8 s, adds only the bottom rung) · TP. Prereq YK.chip (link icon) 'Reduction in the blast furnace'. Stage: the book's equation '3CO + Fe₂O₃ → 2Fe + 3CO₂ (higher than 700 °C)' (p.18) on cue 'سبعمية'. Prereq chip out at line end.","tts_text":"فاكرين الـ blast furnace؟ هناك الـ carbon monoxide فوق سبعمية بيدّي حديد.","screen_text":"Blast furnace: CO higher than 700 °C → iron"},{"id":"s5l3","visual":"[CORE] FB LADDER builds rung 1 '230–300 °C → Fe₃O₄' on cue 'ميتين'; tube 1's solid turns black on cue 'magnetic'.","tts_text":"أول درجة: من ميتين وتلاتين لتلتمية، الـ magnetic iron oxide الأول.","screen_text":"230–300 °C → Fe₃O₄"},{"id":"s5l4","visual":"[CORE] LADDER rung 2 '400–700 °C → FeO' on cue 'ربعمية'; tube 2's solid turns black powder on cue 'بقى'.","tts_text":"من ربعمية لسبعمية: iron اتنين oxide بقى.","screen_text":"400–700 °C → FeO"},{"id":"s5l5","visual":"[CORE] LADDER rung 3 'higher than 700 °C → Fe' on cue 'سبعمية'; tube 3's solid turns grey metal on cue 'الحديد'.","tts_text":"وفوق سبعمية، الـ oxygen كله بيتشال، ويفضل الحديد نفسه.","screen_text":"Higher than 700 °C → Fe"},{"id":"s5l6","visual":"[CORE] FB LADDER: a gold arrow down the rungs on cue 'تعلى'; tag 'more oxygen removed' on cue 'reduction' (G40, fe.conversions misconception #1: same reagent, same product).","tts_text":"يعني كل ما الحرارة تعلى، الـ reduction بيروح لأبعد.","screen_text":"Hotter → more oxygen removed"},{"id":"s5l7","visual":"[CORE] FB MAP (book Evaluation Q6 (a), p.26) builds 'Fe → Fe₃O₄ → FeO → Fe₂O₃ → Fe' LTR on cue 'سؤال'; up-arrows gold on cue 'لفوق'; down-arrows teal on cue 'لتحت'. Legend 'up = oxidation' · 'down = reduction (H₂, CO)'.","tts_text":"سؤال الكتاب: سهم لفوق oxidation بالهوا، وسهم لتحت reduction بالغازات.","screen_text":"Book Q6 (a): up = oxidation · down = reduction (H₂, CO)"},{"id":"s5l8","visual":"[CORE] MAP arrow 1 label 'red hot, dry air (Δ)' on cue 'الأول'; node Fe₃O₄ glows on cue 'magnetic'.","tts_text":"السهم الأول: حديد أحمر مع هوا ناشف، والناتج الـ magnetic iron oxide الأسود.","screen_text":"1. Fe → Fe₃O₄: red hot iron + dry air"},{"id":"s5l9","visual":"[CORE] MAP arrow 2 label 'H₂, 400–700 °C' on cue 'hydrogen'; LADDER middle rung pulses on cue 'ربعمية'.","tts_text":"السهم التاني: iron اتنين oxide، بالـ hydrogen من ربعمية لسبعمية.","screen_text":"2. Fe₃O₄ → FeO: H₂ at 400–700 °C"},{"id":"s5l10","visual":"[CORE] MAP arrow 3 label 'heat in air' on cue 'التالت'; node Fe₂O₃ turns red on cue 'فيتأكسد'.","tts_text":"السهم التالت: نسخّن الـ iron اتنين oxide في الهوا، فيتأكسد على طول.","screen_text":"3. FeO → Fe₂O₃: heat in air"},{"id":"s5l11","visual":"[CORE] MAP arrow 4 label 'CO, higher than 700 °C' on cue 'سبعمية'; the loop closes back to Fe on cue 'furnace'.","tts_text":"والرابع: carbon monoxide فوق سبعمية، زي الـ blast furnace بالظبط.","screen_text":"4. Fe₂O₃ → Fe: CO higher than 700 °C"},{"id":"s5l12","visual":"[CORE] PAUSE-AND-PREDICT part 1 (NEW case: one sample heated step by step; not in the unit's lessons or questions). TP: three temperature tags on cues 'ميتين', 'ستمية', 'سبعمية'; stage: one TUBE, thermometer rising.","tts_text":"نعدّي carbon monoxide على iron تلاتة oxide: ميتين وتمانين، وبعدين ستمية، وبعدين سبعمية وخمسين.","screen_text":"CO over one Fe₂O₃ sample: 280 °C, then 600 °C, then 750 °C"},{"id":"s5l13","visual":"[CORE] PAUSE-AND-PREDICT part 2 · question in the text panel on cue 'مرة'; three empty product boxes; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"يطلع إيه في كل مرة؟ وقّفوا وفكّروا.","screen_text":"Which solid after each step?","pause_after_s":3},{"id":"s5l14","visual":"[CORE] TP: the boxes fill on cues 'magnetic', 'وبعدين', 'حديد' + YK.rightMark; LADDER rungs light top to bottom.","tts_text":"الأول magnetic iron oxide، وبعدين iron اتنين oxide، وفي الآخر حديد.","screen_text":"Fe₃O₄ → FeO → Fe ✓"},{"id":"s5l15","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron and its oxides: reaction diagrams', line:'Same gas, different temperature → different product', formula:'230–300 °C Fe₃O₄ · 400–700 °C FeO · > 700 °C Fe', pulse:[{word:'temperature', at:YK.cue('s5l15','وحرارة')}, {word:'product', at:YK.cue('s5l15','ناتج')}]}).","tts_text":"الخلاصة: نفس الغاز، وحرارة مختلفة، يبقى ناتج مختلف.","screen_text":"Same gas, different temperature → different product"},{"id":"s5l16","visual":"[CORE] SO-WHAT · FB: a FeSO₄ node drops into the MAP on cue 'sulphate'. Segment chip stays (same concept); in the pause: camera move into the PART 6 card.","tts_text":"يلا على الرسمة التانية، وفيها sulphate كمان.","screen_text":"Now diagram (b), with a sulphate in it","pause_after_s":2.5},{"id":"s6l1","style":"curious","visual":"PART 6/6 · fe.conversions · objective: Write the reagents and conditions of conversion diagram (b). · [CORE] Segment card in s5l16's 2.5 s pause (camera move in, no fade): YK.partCard({num:6, of:6, title:'Iron and its oxides: reaction diagrams', objective:'Write the reagents and conditions of conversion diagram (b)', at: cueEnd(previous line)+0.1, collapse: YK.cue('s6l1'), until: end of the micro-recap}); the card collapses into the segment YK.chip (x 96, y 64, map title_en 'Iron and its oxides: reaction diagrams', never cut) on line start, chip kept to the micro-recap. Line: FB MAP (book Evaluation Q6 (b), p.26) nodes LTR 'Fe → FeSO₄ → Fe₂O₃ → Fe₃O₄ → Fe' on cue 'حديد'; all arrows '?' on cue 'إزاي'. Legend 'up = oxidation' (no '(air)': the up arrows here are dil. H₂SO₄ and heating FeSO₄). RE-HOOK.","tts_text":"حديد يبقى sulphate، ويبقى oxide، ويرجع حديد تاني؟ إزاي؟","screen_text":"Iron → sulphate → oxide → back to iron?"},{"id":"s6l2","visual":"PREREQ fe.reaction-dilute-acids (in-book, Unit 8; E2d callback ≤ 8 s, adds only arrow 1) · FB MAP (the s6l1 map stays full-bleed for the whole part; the prereq chip sits beside the segment chip: YK.prereqChip({after: segment title})). Prereq YK.chip (link icon) 'Iron with dilute acids'. MAP arrow 1 label 'dil. H₂SO₄' on cue 'dilute'; node FeSO₄ glows on cue 'sulphate'. Prereq chip out at line end.","tts_text":"فاكرين؟ الحديد مع الـ dilute sulphuric acid بيدّي iron اتنين sulphate كده.","screen_text":"1. Fe → FeSO₄: dilute H₂SO₄"},{"id":"s6l3","visual":"[CORE] QUICK CHECK (≥ 1 s pause, E1a) · FB MAP arrow 2 '?' pulses on cue 'التاني'; YK.thinkRing through the 1.5 s pause.","tts_text":"السهم التاني: إزاي الـ sulphate يبقى oxide أحمر؟","screen_text":"2. FeSO₄ → Fe₂O₃: how?","pause_after_s":1.5},{"id":"s6l4","visual":"[CORE] MAP arrow 2 label 'heat (Δ)' on cue 'نسخّنه' + YK.rightMark; EQ strip under the map (y 900, mono ≥ 52) '2FeSO₄ →Δ Fe₂O₃ + SO₂ + SO₃' on cue 'oxide' (FB).","tts_text":"نسخّنه بس: يطلع iron تلاتة oxide، وغازين من الـ sulphur كمان.","screen_text":"Heat it ✓ 2FeSO₄ → Fe₂O₃ + SO₂ + SO₃"},{"id":"s6l5","visual":"[CORE] MAP arrow 3 label 'CO, 230–300 °C' on cue 'أوطى'; LADDER top rung pulses on cue 'ميتين'.","tts_text":"التالت: carbon monoxide على أوطى درجة، من ميتين وتلاتين لتلتمية.","screen_text":"3. Fe₂O₃ → Fe₃O₄: CO at 230–300 °C"},{"id":"s6l6","visual":"[CORE] MAP arrow 4 label 'CO, higher than 700 °C' on cue 'سبعمية'; node Fe glows on cue 'حديد'; LADDER bottom rung pulses.","tts_text":"والرابع: carbon monoxide فوق سبعمية، ونرجع حديد.","screen_text":"4. Fe₃O₄ → Fe: CO higher than 700 °C"},{"id":"s6l7","visual":"[CORE] MAP extra arrows: up (gold) 'Fe₃O₄ → Fe₂O₃: heat in air' on cue 'يرجع'; down (teal) 'Fe₂O₃ → Fe: CO, higher than 700 °C' on cue 'حديد'. Diagram (b) complete.","tts_text":"وفيها سهمين زيادة: الأسود يرجع أحمر في الهوا، والأحمر يبقى حديد فوق سبعمية.","screen_text":"Extra arrows: Fe₃O₄ → Fe₂O₃ (heat in air) · Fe₂O₃ → Fe (CO, higher than 700 °C)"},{"id":"s6l8","visual":"[CORE] PAUSE-AND-PREDICT part 1 (NEW case: a chain built for this episode; not in the book's Q6 or the unit's lessons or questions). MAP (new, small) 'Fe₂O₃ → X' with arrow label 'CO, 230–300 °C' on cue 'carbon'.","tts_text":"رسمة جديدة: iron تلاتة oxide، وعليه carbon monoxide من ميتين وتلاتين لتلتمية،","screen_text":"New diagram: Fe₂O₃ →(CO, 230–300 °C) X"},{"id":"s6l9","visual":"[CORE] PAUSE-AND-PREDICT part 2 · MAP continues: arrow 'H₂, 400–700 °C' to Y on cue 'hydrogen', arrow 'dil. H₂SO₄' to Z on cue 'dilute'; question on cue 'التلاتة'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"وبعدين hydrogen من ربعمية لسبعمية، وبعدين dilute sulphuric acid. إيه التلاتة؟ وقّفوا وفكّروا.","screen_text":"→(H₂, 400–700 °C) Y →(dilute H₂SO₄) Z. Name X, Y and Z.","pause_after_s":3},{"id":"s6l10","visual":"[CORE] MAP: 'X = Fe₃O₄' on cue 'magnetic', 'Y = FeO' on cue 'والتاني', 'Z = FeSO₄' on cue 'والتالت' + YK.rightMark.","tts_text":"الأول magnetic iron oxide، والتاني iron اتنين oxide، والتالت iron اتنين sulphate كمان.","screen_text":"X = Fe₃O₄ · Y = FeO · Z = FeSO₄ ✓"},{"id":"s6l11","visual":"[CORE] MICRO-RECAP · centred YK.takeaway ({title:'Iron and its oxides: reaction diagrams', line:'Up: oxidation · down: reduction (H₂, CO) · the condition picks the product', pulse:[{word:'oxidation', at:YK.cue('s6l11','oxidation')}, {word:'reduction', at:YK.cue('s6l11','reduction')}]}).","tts_text":"الخلاصة: لفوق oxidation، ولتحت reduction، والشرط هو اللي بيختار الناتج.","screen_text":"Up = oxidation · down = reduction · the condition picks the product"},{"id":"s6l12","visual":"[CORE] SO-WHAT · FB: the OXIDE TRIO shrinks into a row at the bottom on cue 'نلم'. Segment chip out.","tts_text":"يلا نلم الحلقة كلها في سلسلة واحدة.","screen_text":"Now the whole episode in one chain","pause_after_s":1},{"id":"z1","visual":"[CORE] CLOSING SUMMARY · FB. YK.flow({rtl:false}) LTR in book order, nodes ≥ 32 px: node 1 'FeO' (sub 'oxalate, no air · 400–700 °C') on cue 'iron'.","tts_text":"الـ iron اتنين oxide أسود، من الـ oxalate، أو بالـ reduction في النص.","screen_text":"FeO: black · iron (II) oxalate without air · or reduction at 400–700 °C"},{"id":"z2","visual":"[CORE] FB flow: node 2 'Fe₂O₃' (sub 'Fe(OH)₃ · FeSO₄ · iron (III) salt') on cue 'أحمر'.","tts_text":"والـ iron تلاتة oxide أحمر، من الـ hydroxide أو الـ sulphate، ويدّي salt واحد.","screen_text":"Fe₂O₃: red · from Fe(OH)₃ or FeSO₄ · one salt"},{"id":"z3","visual":"[CORE] FB flow: node 3 'Fe₃O₄' (sub 'mixed oxide · two salts') on cue 'mixed'.","tts_text":"والـ iron oxide الأسود ده mixed oxide، فبيدّي اتنين salts مع بعض.","screen_text":"Fe₃O₄: a mixed oxide → two salts"},{"id":"z4","visual":"[CORE] BIG QUESTION ANSWERED · FB: flow node 4 'Reaction diagrams' (sub 'up: oxidation · down: reduction') joins the chain on cue 'باختيار' (closing chain covers Parts 5–6); the cold-open gold tag 'How do we make each oxide?' returns centre with ✓ on cue 'باختيار'; the LADDER and the up/down arrows link the three oxide nodes on cues 'والحرارة', 'الهوا'.","tts_text":"وإجابة سؤالنا: كل oxide بنطلّعه باختيار المادة، والحرارة، ووجود الهوا.","screen_text":"How do we make each oxide? ✓ the temperature and the air decide"},{"id":"z5","visual":"[CORE] RECALL 1/2 (Parts 1 and 5; book Evaluation Q1.4 p.25 wording) · YK.predictCard({kind:'RECALL 1 OF 2', q: screen_text}) in the text panel; stage: TUBE with black Fe₃O₄; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"سؤال الكتاب: reduction للـ magnetic iron oxide من ربعمية لسبعمية، يدّي إيه؟ وقّفوا وفكّروا.","screen_text":"Reducing magnetic iron oxide at 400–700 °C gives …","pause_after_s":3},{"id":"z6","visual":"[CORE] FB close-up (breaks the text-panel run): TUBE with black Fe₃O₄, H₂ arrows, thermometer '400–700 °C'; YK.answerSlot 'FeO ✓' + YK.rightMark on cue 'الإجابة'; formula strip (y 900) 'Fe₃O₄ + H₂ → 3FeO + H₂O' on cue 'تلاتة'.","tts_text":"الإجابة: iron اتنين oxide، تلاتة منه.","screen_text":"FeO ✓"},{"id":"z7","visual":"[CORE] RECALL 2/2 (Part 4; NEW case: identify from two observations; not in the unit's lessons or questions) · YK.predictCard({kind:'RECALL 2 OF 2', q: screen_text}) in the text panel; stage: a black lump on a magnet on cue 'أسود', then red after heating on cue 'بيحمر'; YK.thinkRing from cue 'وفكّروا' through the 3 s pause.","tts_text":"عندنا oxide أسود بيتشد للمغناطيس، وبالتسخين في الهوا بيحمر. مين الاتنين؟ وقّفوا وفكّروا.","screen_text":"A black oxide sticks to a magnet; heated in air, it turns red. Name both oxides.","pause_after_s":3},{"id":"z8","visual":"[CORE] TP answer 'Fe₃O₄ → Fe₂O₃ ✓' + YK.rightMark on cue 'طبعًا'; the OXIDE TRIO lights all three jars for the last frame (0.8 s tail). No teaser (last unit of the chapter).","tts_text":"الأسود magnetic iron oxide، والأحمر iron تلاتة oxide طبعًا.","screen_text":"Fe₃O₄ (magnetic iron oxide) → Fe₂O₃ ✓"}],"logline":"Red paint, a black rock that grabs a magnet and a black powder are all iron oxides: how do we make each one? Six parts in the book's order (pp.22-24, Q6 p.26): iron (II) oxide (iron (II) oxalate heated in absence of air; reducing the higher oxides by H₂ or CO at 400-700 °C; easily oxidized in hot air; with dilute acids an iron (II) salt + water), iron (III) oxide (Fe(OH)₃ above 200 °C; heating FeSO₄ → SO₂ + SO₃; hematite, red pigments; hot concentrated acids → iron (III) salts), magnetic iron oxide (a mixed oxide: air or steam on red hot iron, CO at 230-300 °C; strong magnet; two salts with hot concentrated acids; heated in air → Fe₂O₃) and the book's conversion diagrams, where the temperature ladder decides the 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اللي في البويات ده iron تلاتة oxide\nكده\nوحجر أسود بيشد المغناطيس ده الـ magnetic\niron oxide برضه\nوبودرة سودا ناعمة اسمها iron اتنين oxide\nكده\nوالرقم ده هو الـ oxidation state بتاع\nالحديد جوه كل واحد\nنفس الحديد والـ oxygen إزاي نطلّع كل oxide\nفيهم\nالحلقة دي عن الـ iron oxides التلاتة وإزاي\nبنحوّل واحد للتاني\nعشان نعمل iron اتنين oxide بنسخّن iron\nاتنين oxalate في هوا ولا لأ\nنسخّنه في أنبوبة مقفولة بعيد عن الهوا\nبيدّي iron اتنين oxide و carbon monoxide و\ncarbon dioxide كمان\nليه لأن الـ oxide ده بيحصله oxidation\nبسهولة في الهوا السخن\nأربعة iron اتنين oxide مع oxygen يدّوا\niron تلاتة oxide أحمر\nفاكرين الـ reduction المادة بتخسر oxygen و\nhydrogen أو carbon monoxide بياخدوه\nتاني طريقة reduction للـ higher oxides\nاللي فيها oxygen أكتر لكل حديد\nبنعمل لها reduction بالـ hydrogen أو الـ\ncarbon monoxide من ربعمية لسبعمية درجة\nمن الـ iron تلاتة oxide مع hydrogen اتنين\niron اتنين oxide وبخار مية\nونفس الكلام مع الـ magnetic iron oxide\nتلاتة منه وبخار مية\nنسخّن الـ oxalate في nitrogen بس البودرة\nهتطلع سودا ولا حمرا وقّفوا وفكّروا\nسودا مفيش oxygen يأكسدها فالـ oxide بيفضل\nزي ما هو\nالخلاصة الـ oxalate من غير هوا أو الـ\nhigher oxides من ربعمية لسبعمية\nطيب عملنا الـ oxide ده بيتصرف إزاي بقى\nالـ iron اتنين oxide في dilute acid هيفور\nزي الحديد\nأول خاصية بودرة سودا و insoluble في المية\nتاني خاصية شفناها بيحصله oxidation بسهولة\nفي الهوا السخن\nفاكرين الـ basic oxide مع الـ acid بيدّي\nsalt ومية\nتالت خاصية مع الـ mineral acids يدّي iron\nاتنين salt ومية\nمع الـ dilute sulphuric acid يطلع iron\nاتنين sulphate ومية ومن غير غاز\nالحديد كان اتنين موجب في الـ oxide وفضل\nاتنين موجب بعدها\nفمش بيطلع iron تلاتة مفيش حاجة حصلها\noxidation هنا\nالـ iron اتنين oxide مع dilute hydrobromic\nacid يطلع إيه مع المية وقّفوا وفكّروا\nيطلع iron اتنين bromide والحديد فضل اتنين\nموجب\nالخلاصة بودرة سودا بيحصلها oxidation في\nالهوا ومع الـ dilute acids تدّي salt ومية\nنلم اللي فات وبعدين الـ oxide الأحمر\nنلم اللي فات iron اتنين oxide من الـ\noxalate بالتسخين من غير هوا\nأو من الـ higher oxides بالـ hydrogen أو\nالـ carbon monoxide كمان\nوهو أسود بيحصله oxidation في الهوا السخن\nومع الـ dilute acid يدّي salt ومية\nالـ iron تلاتة oxide الأحمر بنحضّره في\nالمعمل إزاي\nفاكرين الـ precipitate مادة صلبة insoluble\nبتظهر جوه المحلول\nنضيف alkali لمحلول iron تلاتة salt فينزل\nhydroxide بني محمر\nمثال الكتاب iron تلاتة chloride مع\nammonium hydroxide والـ ammonium chloride\nيفضل دايب\nنسخّن الـ hydroxide فوق ميتين درجة فيطلع\niron تلاتة oxide وبخار\nاتنين hydroxide يدّوا oxide واحد وتلات\nجزيئات بخار مية\nالطريقة التانية نسخّن iron اتنين sulphate\nلوحده\nاتنين sulphate يدّوا iron تلاتة oxide و\nsulphur dioxide و sulphur trioxide مع بعض\nالحديد طلع من اتنين لتلاتة والـ sulphur\nخرج في غازين\nوفي الطبيعة هو الـ hematite و insoluble في\nالمية وبيلوّن البويات أحمر\nومع mineral acids سخنة و concentrated يدّي\niron تلاتة salt ومية\nمع الـ sulphuric acid بيطلع iron تلاتة\nsulphate ومية ومفيش غاز\nخدوا بالكم الأسود مع الـ dilute والأحمر مع\nالـ concentrated السخن\nطب iron تلاتة sulphate مع alkali ونسخّن\nالـ precipitate فوق ميتين الناتج وقّفوا\nوفكّروا\nالناتج iron تلاتة oxide أي iron تلاتة salt\nمع alkali يدّي hydroxide والتسخين يكمّل\nالخلاصة الـ iron تلاتة oxide من الـ\nhydroxide أو بتسخين الـ sulphate كمان\nفاضل oxide فيه الاتنين مع بعض إزاي\nأسود وبيشد المغناطيس وجواه اتنين oxides في\nنفس الوقت\nده بيتقال عليه mixed oxide فيه iron اتنين\nو iron تلاتة\nجمّعوا iron اتنين oxide مع iron تلاتة\noxide يطلع هو بالظبط\nوفي الطبيعة اسمه magnetite الخام الأسود\nأول طريقة هوا سخن أو بخار مية على حديد\nأحمر\nالتانية reduction للـ iron تلاتة oxide\nبالـ carbon monoxide من ميتين وتلاتين\nلتلتمية\nتلاتة iron تلاتة oxide مع carbon monoxide\nواحد يدّوا اتنين منه\nأول خاصية ده magnet قوي بيشد الحديد\nتاني خاصية مع الـ concentrated acids\nالسخنة يدّي salts iron اتنين و iron تلاتة\nحتة الـ iron اتنين oxide تدّي iron اتنين\nsulphate ومية\nوحتة الـ iron تلاتة oxide تدّي iron تلاتة\nsulphate وتلات جزيئات مية\nنجمعهم واحد زائد تلاتة يبقى أربعة\nsulphuric acid وأربع جزيئات مية\nطلعوا اتنين salts وده الدليل إنه mixed\noxide مش oxide عادي\nتالت خاصية بالتسخين في الهوا حتة الـ iron\nاتنين بيحصلها oxidation لتلاتة\nاتنين منه مع نص جزيء oxygen يدّوا تلاتة من\nالأحمر\nسخّنا الـ magnetic iron oxide في الهوا\nالأول\nوبعدين حطيناه في concentrated acid سخن كام\nsalt وقّفوا وفكّروا\nواحد بس iron تلاتة sulphate لأنه بقى iron\nتلاتة oxide خلاص\nالخلاصة magnet قوي وبيدّي اتنين salts لأنه\nmixed oxide فعلًا\nنلم الأول وبعدين نرسم خريطة الأسهم\nنلم تاني iron اتنين oxide من الـ oxalate\nأو من ربعمية لسبعمية\nو iron تلاتة oxide من الـ hydroxide أو\nبتسخين الـ sulphate كمان\nوآخر واحد الـ magnetic iron oxide من حديد\nأحمر أو على حرارة واطية\nنفس الـ carbon monoxide ونفس الـ oxide\nونواتج مختلفة\nفاكرين الـ blast furnace هناك الـ carbon\nmonoxide فوق سبعمية بيدّي حديد\nأول درجة من ميتين وتلاتين لتلتمية الـ\nmagnetic iron oxide الأول\nمن ربعمية لسبعمية iron اتنين oxide بقى\nوفوق سبعمية الـ oxygen كله بيتشال ويفضل\nالحديد نفسه\nيعني كل ما الحرارة تعلى الـ reduction\nبيروح لأبعد\nسؤال الكتاب سهم لفوق oxidation بالهوا وسهم\nلتحت reduction بالغازات\nالسهم الأول حديد أحمر مع هوا ناشف والناتج\nالـ magnetic iron oxide الأسود\nالسهم التاني iron اتنين oxide بالـ\nhydrogen من ربعمية لسبعمية\nالسهم التالت نسخّن الـ iron اتنين oxide في\nالهوا فيتأكسد على طول\nوالرابع carbon monoxide فوق سبعمية زي الـ\nblast furnace بالظبط\nنعدّي carbon monoxide على iron تلاتة oxide\nميتين وتمانين وبعدين ستمية وبعدين سبعمية\nوخمسين\nيطلع إيه في كل مرة وقّفوا وفكّروا\nالأول magnetic iron oxide وبعدين iron\nاتنين oxide وفي الآخر حديد\nالخلاصة نفس الغاز وحرارة مختلفة يبقى ناتج\nمختلف\nيلا على الرسمة التانية وفيها sulphate كمان\nحديد يبقى sulphate ويبقى oxide ويرجع حديد\nتاني إزاي\nفاكرين الحديد مع الـ dilute sulphuric acid\nبيدّي iron اتنين sulphate كده\nالسهم التاني إزاي الـ sulphate يبقى oxide\nأحمر\nنسخّنه بس يطلع iron تلاتة oxide وغازين من\nالـ sulphur كمان\nالتالت carbon monoxide على أوطى درجة من\nميتين وتلاتين لتلتمية\nوالرابع carbon monoxide فوق سبعمية ونرجع\nحديد\nوفيها سهمين زيادة الأسود يرجع أحمر في\nالهوا والأحمر يبقى حديد فوق سبعمية\nرسمة جديدة iron تلاتة oxide وعليه carbon\nmonoxide من ميتين وتلاتين لتلتمية\nوبعدين hydrogen من ربعمية لسبعمية وبعدين\ndilute sulphuric acid إيه التلاتة وقّفوا\nوفكّروا\nالأول magnetic iron oxide والتاني iron\nاتنين oxide والتالت iron اتنين sulphate\nكمان\nالخلاصة لفوق oxidation ولتحت reduction\nوالشرط هو اللي بيختار الناتج\nيلا نلم الحلقة كلها في سلسلة واحدة\nالـ iron اتنين oxide أسود من الـ oxalate\nأو بالـ reduction في النص\nوالـ iron تلاتة oxide أحمر من الـ\nhydroxide أو الـ sulphate ويدّي salt واحد\nوالـ iron oxide الأسود ده mixed oxide\nفبيدّي اتنين salts مع بعض\nوإجابة سؤالنا كل oxide بنطلّعه باختيار\nالمادة والحرارة ووجود الهوا\nسؤال الكتاب reduction للـ magnetic iron\noxide من ربعمية لسبعمية يدّي إيه وقّفوا\nوفكّروا\nالإجابة iron اتنين oxide تلاتة منه\nعندنا oxide أسود بيتشد للمغناطيس وبالتسخين\nفي الهوا بيحمر مين الاتنين وقّفوا وفكّروا\nالأسود magnetic iron oxide والأحمر iron\nتلاتة oxide طبعًا","countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"series_id":"chem-s3-en.ch1#sessions","episode_no":9,"episode_count":9,"lessons":["chem-s3-en.lesson-fe.conversions","chem-s3-en.lesson-fe.oxide-fe2o3","chem-s3-en.lesson-fe.oxide-fe3o4","chem-s3-en.lesson-fe.oxide-feo"]},{"id":"chem-s3-en.lesson-phys.electric-charges","kind":"lesson","version":2,"catalog_version":3,"ord":2,"primary_concept_id":"phys.electric-charges","concepts":[{"concept_id":"phys.electric-charges","role":"primary"}],"title":"Electric charges: attraction and repulsion","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"They attract each other","correct":false},{"id":"b","text":"They repel each other","correct":true},{"id":"c","text":"Nothing happens, because electrons are too small","correct":false}],"question":"Two electrons are close to each other. What happens?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"From Cr to Cu, the atoms gain protons but hardly change size. What is pulling, and what is pushing?"},"children":[]},"t2":{"type":"Text","props":{"content":"Start with the basics. Predict:"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","t2","q"]}}},"title":"A pull and a push"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 360 220\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"60\" cy=\"38\" r=\"20\" fill=\"#f87171\" fill-opacity=\"0.25\" stroke=\"#f87171\" stroke-width=\"2.5\"/><text x=\"60\" y=\"46\" text-anchor=\"middle\" font-size=\"24\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"210\" cy=\"38\" r=\"20\" fill=\"#60a5fa\" fill-opacity=\"0.25\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><text x=\"210\" y=\"46\" text-anchor=\"middle\" font-size=\"24\" font-weight=\"700\" fill=\"#60a5fa\">−</text><line x1=\"88.0\" y1=\"38.0\" x2=\"125.0\" y2=\"38.0\" stroke=\"#e2e8f0\" stroke-width=\"2.5\" stroke-linecap=\"round\"/><polygon points=\"125.0,38.0 116.9,41.9 116.9,34.1\" fill=\"#e2e8f0\"/><line x1=\"182.0\" y1=\"38.0\" x2=\"145.0\" y2=\"38.0\" stroke=\"#e2e8f0\" stroke-width=\"2.5\" stroke-linecap=\"round\"/><polygon points=\"145.0,38.0 153.1,34.1 153.1,41.9\" fill=\"#e2e8f0\"/><text x=\"285\" y=\"44\" font-size=\"17\" fill=\"#fbbf24\">attract</text><circle cx=\"60\" cy=\"110\" r=\"20\" fill=\"#60a5fa\" fill-opacity=\"0.25\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><text x=\"60\" y=\"118\" text-anchor=\"middle\" font-size=\"24\" font-weight=\"700\" fill=\"#60a5fa\">−</text><circle cx=\"210\" cy=\"110\" r=\"20\" fill=\"#60a5fa\" fill-opacity=\"0.25\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><text x=\"210\" y=\"118\" text-anchor=\"middle\" font-size=\"24\" font-weight=\"700\" fill=\"#60a5fa\">−</text><line x1=\"34.0\" y1=\"110.0\" x2=\"8.0\" y2=\"110.0\" stroke=\"#e2e8f0\" stroke-width=\"2.5\" stroke-linecap=\"round\"/><polygon points=\"8.0,110.0 16.1,106.1 16.1,113.9\" fill=\"#e2e8f0\"/><line x1=\"236.0\" y1=\"110.0\" x2=\"262.0\" y2=\"110.0\" stroke=\"#e2e8f0\" stroke-width=\"2.5\" stroke-linecap=\"round\"/><polygon points=\"262.0,110.0 253.9,113.9 253.9,106.1\" fill=\"#e2e8f0\"/><text x=\"285\" y=\"116\" font-size=\"17\" fill=\"#e2e8f0\">repel</text><circle cx=\"60\" cy=\"182\" r=\"20\" fill=\"#f87171\" fill-opacity=\"0.25\" stroke=\"#f87171\" stroke-width=\"2.5\"/><text x=\"60\" y=\"190\" text-anchor=\"middle\" font-size=\"24\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"210\" cy=\"182\" r=\"20\" fill=\"#f87171\" fill-opacity=\"0.25\" stroke=\"#f87171\" stroke-width=\"2.5\"/><text x=\"210\" y=\"190\" text-anchor=\"middle\" font-size=\"24\" font-weight=\"700\" fill=\"#f87171\">+</text><line x1=\"34.0\" y1=\"182.0\" x2=\"8.0\" y2=\"182.0\" stroke=\"#e2e8f0\" stroke-width=\"2.5\" stroke-linecap=\"round\"/><polygon points=\"8.0,182.0 16.1,178.1 16.1,185.9\" fill=\"#e2e8f0\"/><line x1=\"236.0\" y1=\"182.0\" x2=\"262.0\" y2=\"182.0\" stroke=\"#e2e8f0\" stroke-width=\"2.5\" stroke-linecap=\"round\"/><polygon points=\"262.0,182.0 253.9,185.9 253.9,178.1\" fill=\"#e2e8f0\"/><text x=\"285\" y=\"188\" font-size=\"17\" fill=\"#e2e8f0\">repel</text></svg>","caption":"+ and − attract. − and − repel. + and + repel.","max_width":360},"children":[]},"atom":{"type":"Text","props":{"content":"In an atom, the protons in the nucleus are positive and the electrons are negative. So the nucleus attracts the electrons."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["term","d","atom","trap"]},"term":{"type":"KeyTerm","props":{"term_en":"Electric charges","definition":"There are two kinds of charge, positive (+) and negative (−). Like charges repel; unlike charges attract."},"children":[]},"trap":{"type":"Misconception","props":{},"children":[]}}},"title":"Like charges repel, unlike charges attract"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"d":2,"q":3},"elements":{"d":{"type":"Slider","props":{"max":5,"min":1,"step":1,"unit":"units","label":"Distance from the nucleus","value":{"$bindState":"/d"}},"children":[]},"q":{"type":"Slider","props":{"max":10,"min":1,"step":1,"label":"Charge of the nucleus (number of protons)","value":{"$bindState":"/q"}},"children":[]},"s":{"type":"Stat","props":{"tone":"brand","label":"Pull on the electron (to compare only)","value":{"args":{"d":{"$state":"/d"},"q":{"$state":"/q"},"expr":"100 * q / d^2","digits":0},"$computed":"calc"}},"children":[]},"t":{"type":"Text","props":{"content":"Change the charge of the nucleus and the distance to the electron. Watch the pull."},"children":[]},"obs":{"type":"BulletList","props":{"items":["More charge → stronger attraction.","Smaller distance → stronger attraction.","The same two rules hold for the repulsion between two electrons."]},"children":[]},"rev":{"type":"Reveal","props":{"label":"Tried both sliders? Tap to see the pattern"},"children":["obs"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q","d","s","rev"]}}},"title":"Stronger or weaker?"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"p1","text":"The nucleus and an electron"},{"id":"p2","text":"Two electrons in the same atom"},{"id":"p3","text":"Two protons"},{"id":"p4","text":"A proton and an electron far apart"}],"answer":{"att":["p1","p4"],"rep":["p2","p3"]},"prompt":"Sort each pair: do they attract or repel?","categories":[{"id":"att","label":"Attract"},{"id":"rep","label":"Repel"}]},"children":[]},"h":{"type":"HintLadder","props":{},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"X, because it has fewer protons","correct":false},{"id":"b","text":"Y, because its nucleus has more positive charge","correct":true},{"id":"c","text":"Both pull equally, because the distance is the same","correct":false}],"question":"Atom X has 11 protons and atom Y has 17 protons. Their outer electrons are at about the same distance from the nucleus. Which nucleus pulls its outer electrons more strongly?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q","h"]}}},"title":"Attract or repel?"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Like charges repel; unlike charges attract.","More charge or less distance means a stronger force.","In an atom, the nucleus attracts the electrons; the electrons repel each other."]},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"All electrons carry a negative charge, and like charges repel. So the electrons in an atom push each other apart, and more charge means a stronger force."},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"next":{"type":"Callout","props":{"variant":"info"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","next","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why adding more electrons to the same atom makes them push each other apart?"},"children":[]}}},"title":"Summary"}],"title":"Electric charges: attraction and repulsion","minutes":4,"book_ref":"Ch.1 p.12-13 relies on it (atomic radius: nuclear attraction to electrons vs repulsion between 3d electrons); prerequisite from earlier grades","subtitle":"The pull and the push inside every atom","objectives":["State that like charges repel and unlike charges attract.","Predict how the force changes with the amount of charge and with distance.","Apply the two rules to the nucleus and the electrons of an atom."],"concept_ids":["phys.electric-charges"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Attraction happens between opposite charges, like a proton and an electron. Two electrons carry the same charge."},{"id":"b","feedback":"Right: both electrons are negative, and like charges repel."},{"id":"c","feedback":"Size does not cancel charge. Every electron carries a negative charge, however tiny it is."}],"explanation":"Both electrons carry a negative charge, and like charges repel, so the two electrons push each other apart."}},"s2":{"trap":{"statement":"Electrons in an atom feel the pull of the nucleus and nothing else.","correction":"Electrons don't only feel the nucleus. They also repel each other, all the time, because they all carry a negative charge."}},"s4":{"c":{"items":[{"id":"p1","feedback":"The nucleus is positive (protons) and the electron is negative, and unlike charges pull towards each other."},{"id":"p2","feedback":"Both are negative. Being in the same atom does not make them attract."},{"id":"p3","feedback":"Both are positive, and like charges push each other away."},{"id":"p4","feedback":"Distance changes how strong the force is, not the signs: a proton and an electron are still unlike charges."}],"explanation":"The signs decide attract or repel. The amount of charge and the distance decide how strong."},"h":{"hints":["The distance is the same, so only one thing differs.","More protons means more positive charge in the nucleus."]},"q":{"options":[{"id":"a","feedback":"Fewer protons means less positive charge, so a weaker pull."},{"id":"b","feedback":"Yes: same distance, more charge, so a stronger attraction."},{"id":"c","feedback":"Distance is only one factor. The amount of charge matters too, and 17 protons give more positive charge than 11."}],"explanation":"With the distance fixed, more protons means a stronger nuclear attraction."}},"s5":{"exam":{"body":"**nuclear attraction** to electrons; **repulsion force** between electrons (Ch.1 p.12-13).","title":"Words the book uses"},"next":{"body":"From Cr to Cu, more nuclear charge pulls; the extra 3d electrons push. Ch.1 explains this tug-of-war.","title":"Back to the hook (coming up in Ch.1)"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"التجاذب بيحصل بين charges مختلفة، زي proton و electron. إنما الـ electrons الاتنين شايلين نفس الـ charge."},{"id":"b","feedback":"صح: الـ electrons الاتنين negative، والـ like charges بتتنافر."},{"id":"c","feedback":"الحجم مش بيلغي الـ charge. كل electron شايل negative charge، مهما كان صغير."}],"explanation":"الـ electrons الاتنين شايلين negative charge، والـ like charges بتتنافر، فالاتنين بيزقّوا بعض بعيد."}},"s2":{"trap":{"statement":"الـ electrons اللي في الذرة مش بيحسّوا غير بشدّ الـ nucleus.","correction":"الـ electrons مش بيحسّوا بالـ nucleus لوحدها. هما كمان بيتنافروا مع بعض طول الوقت، عشان كلهم شايلين negative charge."}},"s4":{"c":{"items":[{"id":"p1","feedback":"الـ nucleus positive (فيها protons) والـ electron negative، يعني unlike charges."},{"id":"p2","feedback":"الاتنين negative. إنهم في نفس الذرة مش هيخليهم يتجاذبوا."},{"id":"p3","feedback":"الاتنين positive، يعني like charges."},{"id":"p4","feedback":"المسافة بتغيّر القوة قد إيه، لكن مش بتغيّر الإشارات."}],"explanation":"الإشارات هي اللي بتحدد تجاذب ولا تنافر. أما كمية الـ charge والمسافة فهما اللي بيحددوا القوة قد إيه."},"h":{"hints":["المسافة واحدة، يعني الفرق في حاجة واحدة تانية.","protons أكتر يعني positive charge أكتر في الـ nucleus."]},"q":{"options":[{"id":"a","feedback":"protons أقل يعني positive charge أقل، يعني شدّ أضعف."},{"id":"b","feedback":"أيوه: نفس المسافة، charge أكتر، يبقى التجاذب أقوى."},{"id":"c","feedback":"المسافة عامل واحد من العوامل. كمية الـ charge كمان ليها دور، و17 protons بيدّوا positive charge أكتر من 11."}],"explanation":"طالما المسافة ثابتة، protons أكتر يعني nuclear attraction أقوى."}},"s5":{"exam":{"body":"**nuclear attraction** للـ electrons؛ و**repulsion force** بين الـ electrons (الفصل الأول، ص.12-13).","title":"الكلمات اللي الكتاب بيستخدمها"},"next":{"body":"من Cr لـ Cu، الـ nuclear charge اللي بتزيد بتشدّ، والـ 3d electrons الزيادة بتزقّ. الفصل الأول بيشرح شدّ الحبل ده.","title":"نرجع لأول الدرس (هنشوفه في الفصل الأول)"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":1,"is_basics":true,"lesson_no":1,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-phys.electric-charges","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Electric charges: attraction and repulsion: from zero","duration_s":314.399,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-phys.electric-charges","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Electric charges attract and repel","duration_s":47.66,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-sci.matter-particles","kind":"lesson","version":2,"catalog_version":3,"ord":4,"primary_concept_id":"sci.matter-particles","concepts":[{"concept_id":"sci.matter-particles","role":"primary"}],"title":"Matter is made of atoms and molecules","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"To use less metal","correct":false},{"id":"b","text":"Because the metal gets longer when it gets hot","correct":true},{"id":"c","text":"Because solid metal never changes its size","correct":false}],"question":"Predict:"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Railway tracks are laid with small gaps between the steel rails. 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A molecule of a compound has atoms of different kinds, like $\\ce{H2O}$."},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why $\\ce{O2}$ is a molecule but not a compound?"},"children":[]}}},"title":"Summary"}],"title":"Matter is made of atoms and molecules","minutes":4,"book_ref":"Ch.1 p.6 and p.13 rely on it (molecular volume of the chromium oxide vs the metal atoms; 'ions or atoms or molecules'); prerequisite from earlier grades","subtitle":"The particle picture behind every metal and compound","objectives":["Describe matter as tiny particles that are always moving, with spaces between them.","Tell an atom from a molecule.","Tell a molecule of an element from a molecule of a compound."],"concept_ids":["sci.matter-particles"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"The gaps are tiny, so they save almost no metal. Saving metal is not why they are there."},{"id":"b","feedback":"Right. Heat makes the particles of the metal move more, so they need more space."},{"id":"c","feedback":"Solid metal does change size: heat makes its particles vibrate more and spread out. If the rails never changed size, no gaps would be needed."}],"explanation":"The gaps are there because metal gets longer when it gets hot: its particles vibrate more and spread out. The gaps leave room for that expansion."}},"s2":{"trap":{"statement":"The particles of a solid do not move.","correction":"Solid particles do move: they vibrate. 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The rail gaps show it: heat makes them vibrate more.","feedback_false":"Correct: they vibrate in place, and they vibrate more when heated."}},"s5":{"exam":{"body":"Ch.1 p.13: paramagnetism appears in **ions or atoms or molecules** with unpaired electrons.","title":"Where you will meet it"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الفراغات دي صغيرة جدًا، فمش بتوفّر حاجة تقريبًا من الـ metal. يعني التوفير مش هو سببها."},{"id":"b","feedback":"صح. الحرارة بتخلي الـ particles بتاعة الـ metal تتحرك أكتر، فتحتاج مساحة أكبر."},{"id":"c","feedback":"الـ metal الـ solid حجمه بيتغير: الحرارة بتخلي الـ particles بتاعته تهتز أكتر وتتباعد. ولو حجم القضبان مش بيتغير، مكناش هنحتاج فراغات."}],"explanation":"الفراغات دي موجودة عشان الـ metal بيطول لما يسخن: الـ particles بتاعته بتهتز أكتر وتتباعد. والفراغات بتسيب مكان للتمدد ده."}},"s2":{"trap":{"statement":"الـ particles بتاعة الـ solid مش بتتحرك.","correction":"لأ، الـ particles بتاعة الـ solid بتتحرك: بتهتز في مكانها. والحرارة بتخليها تهتز أكتر وتتباعد، عشان كده القضيب السخن بيطول."}},"s3":{"trap":{"statement":"الـ molecule لازم تكون متكوّنة من atoms مختلفة.","correction":"الـ molecule مش محتاجة atoms مختلفة. الـ $\\ce{O2}$ مثلًا molecule متكوّنة من نوع واحد من الـ atoms."}},"s4":{"c":{"items":[{"id":"n2","feedback":"الـ atoms الاتنين nitrogen، يعني نوع واحد من الـ atoms."},{"id":"co2","feedback":"الـ C والـ O نوعين مختلفين من الـ atoms."},{"id":"cl2","feedback":"اتنين chlorine atoms، يعني نوع واحد لا غير. الـ molecule ممكن تتكوّن من atoms متطابقة."},{"id":"nh3","feedback":"الـ N والـ H نوعين مختلفين من الـ atoms مرتبطين ببعض."},{"id":"co","feedback":"حرفين: C و O، يعني نوعين من الـ atoms."}],"explanation":"الـ molecule بتاعة الـ element متكوّنة من نوع واحد من الـ atoms ($\\ce{N2}$، $\\ce{Cl2}$)، حتى لو فيها اتنين atoms. أما الـ molecule بتاعة الـ compound فمتكوّنة من أنواع مختلفة من الـ atoms ($\\ce{CO2}$، $\\ce{NH3}$، $\\ce{CO}$). عشان كده بنعدّ أنواع الـ atoms، مش عدد الـ atoms."},"tf":{"explanation":"الـ particles بتاعة الـ matter دايمًا بتتحرك. وفي الـ solid بتهتز في مكانها.","feedback_true":"دي فكرة منتشرة، لكن الـ particles بتاعة الـ solid بتهتز في مكانها. افتكر فراغات القضبان: الحرارة بتخليها تهتز أكتر.","feedback_false":"مظبوط: بتهتز في مكانها، وبتهتز أكتر لما تسخن."}},"s5":{"exam":{"body":"في الفصل الأول، صفحة 13: الـ paramagnetism بيظهر في الـ **ions or atoms or molecules** اللي فيها unpaired electrons.","title":"هتقابلها فين"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":2,"is_basics":true,"lesson_no":2,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-sci.matter-particles","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Matter is made of atoms and molecules: from zero","duration_s":258.69,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-sci.matter-particles","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Matter is made of atoms and molecules","duration_s":47.11,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-atom.atomic-mass-number","kind":"lesson","version":4,"catalog_version":3,"ord":6,"primary_concept_id":"atom.atomic-mass-number","concepts":[{"concept_id":"atom.atomic-mass-number","role":"primary"}],"title":"Atomic number and mass number","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The protons in the nucleus","correct":true},{"id":"b","text":"The protons and the neutrons together","correct":false},{"id":"c","text":"The protons and the electrons together","correct":false}],"question":"Predict: in $_{26}\\text{Fe}$, what does 26 count?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"The book writes $_{26}\\text{Fe}$ and talks about cobalt 60. 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Scandium is 21 and zinc is 30."},"children":[]},"ion":{"type":"Callout","props":{"variant":"tip"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["term","f","t","ion"]},"term":{"type":"KeyTerm","props":{"term_en":"Atomic number","definition":"The number of protons in the nucleus of an atom."},"children":[]}}},"title":"Atomic number (Z)"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"A = Z + N \\qquad N = A - Z","caption":"A = mass number, Z = atomic number, N = number of neutrons"},"children":[]},"cb":{"type":"BulletList","props":{"items":["Z = 27, so 27 protons.","A neutral atom, so 27 electrons.","Neutrons = 60 − 27 = 33."],"ordered":true},"children":[]},"cf":{"type":"Formula","props":{"latex":"^{60}_{27}\\text{Co}"},"children":[]},"card":{"type":"Card","props":{"tone":"brand","title":"Worked example: cobalt 60"},"children":["cf","cb"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["term","f","card","trap"]},"term":{"type":"KeyTerm","props":{"term_en":"Mass number","definition":"The sum of the numbers of protons and neutrons in the nucleus."},"children":[]},"trap":{"type":"Misconception","props":{},"children":[]}}},"title":"Mass number"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"n":30,"z":26},"elements":{"n":{"type":"Slider","props":{"max":40,"min":20,"step":1,"label":"Neutrons","value":{"$bindState":"/n"}},"children":[]},"t":{"type":"Text","props":{"content":"Change the protons and the neutrons. Watch what changes."},"children":[]},"z":{"type":"Slider","props":{"max":30,"min":21,"step":1,"label":"Protons (atomic number Z)","value":{"$bindState":"/z"}},"children":[]},"sa":{"type":"Stat","props":{"tone":"brand","label":"Mass number (A)","value":{"args":{"n":{"$state":"/n"},"z":{"$state":"/z"},"expr":"z + n","digits":0},"$computed":"calc"}},"children":[]},"se":{"type":"Stat","props":{"tone":"info","label":"Electrons in the neutral atom","value":{"args":{"z":{"$state":"/z"},"expr":"z","digits":0},"$computed":"calc"}},"children":[]},"e21":{"type":"Text","props":{"content":"Z = 21: this is **scandium, Sc**."},"visible":{"eq":21,"$state":"/z"},"children":[]},"e22":{"type":"Text","props":{"content":"Z = 22: this is **titanium, Ti**."},"visible":{"eq":22,"$state":"/z"},"children":[]},"e23":{"type":"Text","props":{"content":"Z = 23: this is **vanadium, V**."},"visible":{"eq":23,"$state":"/z"},"children":[]},"e24":{"type":"Text","props":{"content":"Z = 24: this is **chromium, Cr**."},"visible":{"eq":24,"$state":"/z"},"children":[]},"e25":{"type":"Text","props":{"content":"Z = 25: this is **manganese, Mn**."},"visible":{"eq":25,"$state":"/z"},"children":[]},"e26":{"type":"Text","props":{"content":"Z = 26: this is **iron, Fe**."},"visible":{"eq":26,"$state":"/z"},"children":[]},"e27":{"type":"Text","props":{"content":"Z = 27: this is **cobalt, Co**."},"visible":{"eq":27,"$state":"/z"},"children":[]},"e28":{"type":"Text","props":{"content":"Z = 28: this is **nickel, Ni**."},"visible":{"eq":28,"$state":"/z"},"children":[]},"e29":{"type":"Text","props":{"content":"Z = 29: this is **copper, Cu**."},"visible":{"eq":29,"$state":"/z"},"children":[]},"e30":{"type":"Text","props":{"content":"Z = 30: this is **zinc, Zn**."},"visible":{"eq":30,"$state":"/z"},"children":[]},"rev":{"type":"Reveal","props":{"label":"Change only the neutrons. 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What is its mass number?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"An atom of $^{58}_{28}\\text{Ni}$ has ___ protons, ___ electrons and ___ neutrons.","answers":[["28"],["28"],["30"]],"mistakes":[{"id":"m1","blank":0,"answer":"58"},{"id":"m2","blank":1,"answer":"30"},{"id":"m3","blank":1,"answer":"58"},{"id":"m4","blank":2,"answer":"58"},{"id":"m5","blank":2,"answer":"86"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fb","q"]}}},"title":"Count the particles"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Atomic number (Z) = protons = electrons in a neutral atom: $_{26}\\text{Fe}$ has 26.","Mass number (A) = protons + neutrons: cobalt 60 has A = 60.","Neutrons = A − Z: 60 − 27 = 33."]},"children":[]},"r":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Show the answer"}},"children":["ra"]},"ra":{"type":"Text","props":{"content":"$\\ce{Fe^2+}$ has lost 2 electrons, so it has 24 electrons. It still has 26 protons, and the element is fixed by Z, the number of protons."},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Where you will use it"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","r"]},"self":{"type":"Text","props":{"content":"Can you explain why $\\ce{Fe^2+}$ has 24 electrons but is still iron?"},"children":[]}}},"title":"Summary"}],"title":"Atomic number and mass number","minutes":5,"book_ref":"Ch.1 p.4, p.7-8 relies on it (₂₁Sc ... ₃₀Zn; cobalt 60); prerequisite from earlier grades","subtitle":"What the 26 in ₂₆Fe and the 60 in cobalt 60 mean","objectives":["Give the number of protons and electrons of an atom from its atomic number (Z).","Calculate the mass number and the number of neutrons.","Read the notation $^{A}_{Z}\\text{X}$."],"concept_ids":["atom.atomic-mass-number"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Right. 26 is the atomic number of iron: 26 protons."},{"id":"b","feedback":"Protons and neutrons together give the mass number, and for iron that total is bigger than 26."},{"id":"c","feedback":"Iron has 26 protons and 26 electrons. Together that would be 52, not 26."}],"explanation":"In $_{26}\\text{Fe}$, 26 is the atomic number: the number of protons in the nucleus. Protons and neutrons together give the mass number."}},"s2":{"ion":{"body":"This holds for a neutral atom only. $\\ce{Fe^2+}$ has lost 2 electrons: still 26 protons, but 24 electrons.","title":"Neutral atoms only"}},"s3":{"trap":{"statement":"The mass number counts the electrons too.","correction":"Electrons are not counted in the mass number: they are very light compared with protons and neutrons."}},"s5":{"q":{"options":[{"id":"a","feedback":"29 is the atomic number. The mass number adds the neutrons too."},{"id":"b","feedback":"Yes: mass number = protons + neutrons = 29 + 34 = 63."},{"id":"c","feedback":"It looks like the electrons were counted too (29 + 34 + 29). Electrons are too light to count in the mass number."},{"id":"d","feedback":"This is a subtraction. The mass number is the sum of the protons and the neutrons."}],"explanation":"Mass number = protons + neutrons = 29 + 34 = 63. The electrons are not counted, because they are too light."},"fb":{"mistakes":[{"id":"m1","feedback":"58 is the mass number (protons + neutrons). The protons are the atomic number, the lower number."},{"id":"m2","feedback":"In a neutral atom, the electrons equal the protons, not the neutrons."},{"id":"m3","feedback":"The electrons are not in the mass number. In a neutral atom they equal the protons."},{"id":"m4","feedback":"58 is protons + neutrons together. Take away the protons."},{"id":"m5","feedback":"It looks like 58 and 28 were added. Neutrons = mass number − atomic number."}],"explanation":"Protons = Z = 28; electrons = 28 (neutral atom); neutrons = 58 − 28 = 30."}},"s6":{"exam":{"body":"Use the **atomic number** to count the electrons before writing an **electron configuration** in Ch.1."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"صح. الـ 26 ده الـ atomic number بتاع الـ iron: يعني 26 protons."},{"id":"b","feedback":"الـ protons والـ neutrons مع بعض هما الـ mass number، وده للـ iron رقم أكبر من 26."},{"id":"c","feedback":"الـ iron فيه 26 protons و26 electrons. لو جمعتهم هيطلعوا 52، مش 26."}],"explanation":"في $_{26}\\text{Fe}$، الـ 26 هو الـ atomic number: عدد الـ protons اللي في الـ nucleus. أما الـ protons والـ neutrons مع بعض فهما الـ mass number."}},"s2":{"ion":{"body":"الكلام ده للذرة المتعادلة تحديدًا. الـ $\\ce{Fe^2+}$ فقد 2 electrons: لسه فيه 26 protons، لكن فيه 24 electrons.","title":"للذرة المتعادلة تحديدًا"}},"s3":{"trap":{"statement":"الـ mass number بيعدّ الـ electrons كمان.","correction":"الـ electrons مش بتتحسب في الـ mass number: خفيفة جدًا لو قارنتها بالـ protons والـ neutrons."}},"s5":{"q":{"options":[{"id":"a","feedback":"الـ 29 ده الـ atomic number. الـ mass number بيضيف الـ neutrons كمان."},{"id":"b","feedback":"أيوه: الـ mass number = protons + neutrons = 29 + 34 = 63."},{"id":"c","feedback":"شكلك عدّيت الـ electrons كمان (29 + 34 + 29). الـ electrons خفيفة جدًا ومش بتتحسب في الـ mass number."},{"id":"d","feedback":"ده طرح. الـ mass number هو مجموع الـ protons والـ neutrons."}],"explanation":"الـ mass number = protons + neutrons = 29 + 34 = 63. والـ electrons مش بتتحسب، عشان خفيفة جدًا."},"fb":{"mistakes":[{"id":"m1","feedback":"الـ 58 ده الـ mass number (protons + neutrons). الـ protons هي الـ atomic number، الرقم اللي تحت."},{"id":"m2","feedback":"في الذرة المتعادلة، الـ electrons بتساوي الـ protons، مش الـ neutrons."},{"id":"m3","feedback":"الـ electrons مش داخلة في الـ mass number. وفي الذرة المتعادلة عددها بيساوي الـ protons."},{"id":"m4","feedback":"الـ 58 دي protons + neutrons مع بعض. اطرح منها الـ protons."},{"id":"m5","feedback":"شكلك جمعت 58 و28. الـ Neutrons = mass number − atomic number."}],"explanation":"الـ protons = Z = 28؛ الـ electrons = 28 (ذرة متعادلة)؛ الـ neutrons = 58 − 28 = 30."}},"s6":{"exam":{"body":"هتستخدم الـ **atomic number** عشان تعدّ الـ electrons قبل ما تكتب الـ **electron configuration** في الفصل الأول."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":3,"is_basics":true,"lesson_no":3,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-atom.atomic-mass-number","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Atomic number and mass number: from zero","duration_s":281.749,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-atom.atomic-mass-number","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Atomic number and mass number","duration_s":43.7,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.lesson-atom.energy-levels","kind":"lesson","version":4,"catalog_version":3,"ord":8,"primary_concept_id":"atom.energy-levels","concepts":[{"concept_id":"atom.energy-levels","role":"primary"}],"title":"Main energy levels","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"8","correct":false},{"id":"b","text":"18","correct":true},{"id":"c","text":"16","correct":false},{"id":"d","text":"9","correct":false}],"question":"How many electrons can the third level (M) hold at most?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Calcium's 20 electrons are arranged in 4 energy levels around the nucleus. How many electrons fit in each level?"},"children":[]},"t2":{"type":"Text","props":{"content":"The first level (K) holds 2. The second (L) holds 8. 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In a neutral atom, the number of electrons = Z. See how they are arranged."},"children":[]},"z":{"type":"Slider","props":{"max":20,"min":1,"step":1,"label":"Atomic number (Z)","value":{"$bindState":"/z"}},"children":[]},"cols":{"type":"Stack","props":{"gap":"sm","direction":"horizontal"},"children":["k","l","m","n"]},"look":{"type":"Callout","props":{"variant":"info"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","z","cols","term","look"]},"term":{"type":"KeyTerm","props":{"term_en":"Valence electrons","definition":"The electrons in the outermost energy level of the atom (for the main-group atoms in this lesson, Z = 1 to 20)."},"children":[]}}},"title":"Arrange the electrons"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Its atomic number is 17, and it has 7 valence electrons","correct":true},{"id":"b","text":"Its atomic number is 7","correct":false},{"id":"c","text":"It has 17 valence electrons","correct":false},{"id":"d","text":"Its M level is full","correct":false}],"question":"An atom has the arrangement 2, 8, 7. 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That is why you count the symbols (capital letters), not the atoms."},"q":{"options":[{"id":"a","feedback":"Right: K, Mn and O. Mn is one symbol: a capital M and a small n."},{"id":"b","feedback":"4 is the number of oxygen atoms, not the number of different elements."},{"id":"c","feedback":"6 is the number of atoms: 1 K + 1 Mn + 4 O. Atoms of the same element count as one element."}],"explanation":"$\\ce{KMnO4}$ contains 3 different elements: K, Mn and O. Mn is one symbol (capital M, small n), and the 4 counts oxygen atoms, not elements."}},"s5":{"exam":{"body":"The first transition series: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn. 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The period number = the number of occupied main energy levels."},"children":[]}}},"title":"Periods: the rows"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"The table has 18 vertical columns. In the main (A) groups, the Roman numeral = the number of valence electrons."},"children":[]},"pt":{"type":"PeriodicTable","props":{"labels":{"Cl":"2, 8, 7","Mg":"2, 8, 2"},"caption":"Mg is in group IIA (2); Cl is in group VIIA (17).","highlight_groups":[2,17]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["term","t","pt","trap"]},"term":{"type":"KeyTerm","props":{"term_en":"Group","definition":"A vertical column of the periodic table. In the main (A) groups, elements in the same group have similar properties."},"children":[]},"trap":{"type":"TrueFalse","props":{"answer":false,"statement":"Calcium and bromine are both in period 4, so they have similar chemical properties."},"children":[]}}},"title":"Groups: the columns"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Period 4, group IA (1)","correct":true},{"id":"b","text":"Period 1, group IVA","correct":false},{"id":"c","text":"Period 3, group IA","correct":false},{"id":"d","text":"Period 4, group 19","correct":false}],"question":"Atom X has the arrangement 2, 8, 8, 1. Where is it in the periodic table?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Sodium (2, 8, 1) and chlorine (2, 8, 7) are in the same period, so they have similar chemical properties."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf","h"]}}},"title":"Find the address"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Elements are ordered by increasing atomic number: 7 periods, 18 columns.","Period number = number of occupied main energy levels.","Main (A) groups: group number = number of valence electrons."]},"children":[]},"tbl":{"type":"DataTable","props":{"rows":[["Mg","2, 8, 2",3,"IIA"],["Cl","2, 8, 7",3,"VIIA"],["K","2, 8, 8, 1",4,"IA"],["Ca","2, 8, 8, 2",4,"IIA"]],"caption":"Count the levels for the period; read the valence electrons for the A group.","headers":["Element","Arrangement","Period","Group"]},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"hook":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Back to the hook"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tbl","hook","exam","self"]},"self":{"type":"Text","props":{"content":"Can you explain why potassium and calcium are in the same period but in different groups?"},"children":[]}}},"title":"Summary"}],"title":"Periodic table: periods and groups","minutes":5,"book_ref":"Ch.1 p.3-4 relies on it (long form of the periodic table; s and p blocks on both sides; the first transition series in the fourth period after calcium); prerequisite from earlier grades","subtitle":"Find an element's address from its electrons","objectives":["Describe the modern periodic table: elements in order of increasing atomic number, in 7 periods and 18 columns.","Find the period of an element from the number of its occupied main energy levels.","Find the A group of a main-group element from its valence electrons."],"concept_ids":["pt.groups-periods"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"2 is the number of valence electrons. That gives the group, not the period."},{"id":"b","feedback":"Right. Its electrons occupy 4 main energy levels, so it is in period 4."},{"id":"c","feedback":"20 is the atomic number. There are only 7 periods."}],"explanation":"Calcium's arrangement 2, 8, 8, 2 uses 4 main energy levels, and the period number equals the number of occupied main energy levels, so calcium is in period 4. Its 2 valence electrons give its group, and 20 is its atomic number."}},"s3":{"trap":{"explanation":"Ca and Br share period 4, but they are in different A groups (IIA and VIIA). In the main (A) groups, similar properties go with the same group, not the same period. Group VIII is different: you will meet it in Ch.1.","feedback_true":"Not quite. In the main (A) groups, similar properties go with the same group, not the same period. Ca (group IIA) behaves like Mg (group IIA), not like Br (group VIIA).","feedback_false":"Correct: Ca and Br share period 4 but sit in different A groups (IIA and VIIA), so they behave differently. Mg and Ca, both in group IIA, behave alike."}},"s4":{"h":{"hints":["Count the numbers in the arrangement: that is the number of levels.","The last number is the valence electrons."]},"q":{"options":[{"id":"a","feedback":"Yes: 4 occupied levels give period 4, and 1 valence electron gives group IA."},{"id":"b","feedback":"The two are swapped. The levels give the period; the valence electrons give the group."},{"id":"c","feedback":"Count all the occupied levels: K, L, M and N. That is 4, not 3."},{"id":"d","feedback":"19 is the atomic number. There are only 18 columns, so it cannot be a group number; the 1 valence electron gives group IA."}],"explanation":"The arrangement 2, 8, 8, 1 has 4 occupied main energy levels, so X is in period 4. The last number, 1 valence electron, puts it in group IA (1)."},"tf":{"explanation":"In the main (A) groups, elements with the same number of valence electrons (same group) behave alike.","feedback_true":"In the main (A) groups, similar properties go with the same group, not the same period. Across period 3, Na is a metal and Cl is a non-metal.","feedback_false":"Correct: Na and Cl are in different A groups (IA and VIIA), so they behave differently."}},"s5":{"exam":{"body":"**Period** = a horizontal row. **Group** = a vertical column."},"hook":{"body":"Calcium (2, 8, 8, 2): period 4, group IIA. The first transition series follows it in period 4 (Ch.1 p.4)."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"2 ده عدد الـ valence electrons، وده بيحدد الـ group مش الـ period."},{"id":"b","feedback":"صح. الـ electrons بتاعته موجودة في 4 main energy levels، يبقى هو في period 4."},{"id":"c","feedback":"20 ده الـ atomic number. والـ periods عددهم 7 مش أكتر."}],"explanation":"ترتيب الـ calcium 2, 8, 8, 2 فيه 4 main energy levels، ورقم الـ period بيساوي عدد الـ main energy levels اللي فيها electrons، يبقى الـ calcium في period 4. أما الـ 2 valence electrons فبيحددوا الـ group، و20 ده الـ atomic number."}},"s3":{"trap":{"explanation":"الـ Ca والـ Br في نفس period 4، لكن في A groups مختلفة (IIA و VIIA). وفي الـ main (A) groups، الخواص المتشابهة بتمشي مع نفس الـ group مش نفس الـ period. الـ group VIII حكايته مختلفة، وهتقابله في الفصل الأول.","feedback_true":"لأ. في الـ main (A) groups، الخواص المتشابهة بتمشي مع نفس الـ group، مش نفس الـ period. الـ Ca (group IIA) بيتصرف زي الـ Mg (group IIA)، مش زي الـ Br (group VIIA).","feedback_false":"مظبوط: الـ Ca والـ Br في نفس period 4، لكن في A groups مختلفة (IIA و VIIA)، عشان كده سلوكهم مختلف. إنما الـ Mg والـ Ca، الاتنين في group IIA، بيتصرفوا بشكل متشابه."}},"s4":{"h":{"hints":["عِدّ الأرقام اللي في الترتيب: ده عدد المستويات.","آخر رقم هو عدد الـ valence electrons."]},"q":{"options":[{"id":"a","feedback":"أيوه: 4 مستويات فيها electrons يبقى period 4، و valence electron واحد يبقى group IA."},{"id":"b","feedback":"إنت عكست الاتنين. المستويات هي اللي بتحدد الـ period، والـ valence electrons هي اللي بتحدد الـ group."},{"id":"c","feedback":"عِدّ المستويات اللي فيها electrons كلها: K و L و M و N. يبقوا 4 مش 3."},{"id":"d","feedback":"19 ده الـ atomic number. والجدول فيه 18 عمود بس، فمينفعش يبقى رقم group؛ والـ valence electron الواحد بيدّي group IA."}],"explanation":"الترتيب 2, 8, 8, 1 فيه 4 main energy levels فيها electrons، يبقى X في period 4. وآخر رقم، valence electron واحد، بيحطه في group IA (1)."},"tf":{"explanation":"في الـ main (A) groups، العناصر اللي ليها نفس عدد الـ valence electrons (يعني نفس الـ group) بتتصرف بشكل متشابه.","feedback_true":"في الـ main (A) groups، الخواص المتشابهة بتمشي مع نفس الـ group، مش نفس الـ period. ولو مشيت على period 3 هتلاقي الـ Na metal والـ Cl non-metal.","feedback_false":"مظبوط: الـ Na والـ Cl في A groups مختلفة (IA و VIIA)، عشان كده سلوكهم مختلف."}},"s5":{"exam":{"body":"**Period** = صف أفقي. **Group** = عمود رأسي."},"hook":{"body":"الـ calcium (2, 8, 8, 2): period 4، group IIA. وبعده في period 4 بتيجي الـ first transition series (Ch.1 p.4)."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":6,"is_basics":true,"lesson_no":6,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-pt.groups-periods","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Periodic table: periods and groups: from zero","duration_s":267.04,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-pt.groups-periods","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Periodic table: periods and groups","duration_s":40.01,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-atom.sublevels","kind":"lesson","version":2,"catalog_version":3,"ord":14,"primary_concept_id":"atom.sublevels","concepts":[{"concept_id":"atom.sublevels","role":"primary"}],"title":"Energy sublevels (s, p, d, f)","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Because only 10 such elements are known","correct":false},{"id":"b","text":"Because the sublevel filled there holds up to 10 electrons","correct":true},{"id":"c","text":"Because each period has 10 elements","correct":false}],"question":"Predict: why 10 columns?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"The middle block of the periodic table has exactly 10 columns. Why 10, and not 8 or 18?"},"children":[]},"pt":{"type":"PeriodicTable","props":{"caption":"The middle block: 10 columns (Ch.1 p.3)","highlight_blocks":["d"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","pt","q"]}}},"title":"Ten columns in the middle"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"tbl":{"type":"DataTable","props":{"rows":[["K",1,"1s",2],["L",2,"2s, 2p",8],["M",3,"3s, 3p, 3d",18],["N",4,"4s, 4p, 4d, 4f",32]],"caption":"Number of sublevels = n. Each sublevel holds at most: s 2, p 6, d 10, f 14.","headers":["Main level","n","Sublevels","Maximum electrons"],"highlight":[{"col":2,"row":2}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["term","tbl","trap"]},"term":{"type":"KeyTerm","props":{"term_en":"Energy sublevels","definition":"The parts that a main energy level is divided into: s, p, d and f."},"children":[]},"trap":{"type":"Misconception","props":{},"children":[]}}},"title":"Levels are divided into sublevels"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"n":3},"elements":{"a":{"type":"Stat","props":{"tone":"brand","label":"Sublevels","value":{"args":{"n":{"$state":"/n"},"expr":"n","digits":0},"$computed":"calc"}},"children":[]},"b":{"type":"Stat","props":{"tone":"info","label":"Maximum electrons (2n²)","value":{"args":{"n":{"$state":"/n"},"expr":"2 * n^2","digits":0},"$computed":"calc"}},"children":[]},"n":{"type":"Slider","props":{"max":4,"min":1,"step":1,"label":"Main energy level (n)","value":{"$bindState":"/n"}},"children":[]},"t":{"type":"Text","props":{"content":"Choose a main level. See which sublevels it has."},"children":[]},"t2":{"type":"Text","props":{"muted":true,"content":"Add up the sublevels: you get the $2n^2$ of the level."},"children":[]},"v1":{"type":"Text","props":{"content":"K (n = 1): **1s** → 2 electrons"},"visible":{"eq":1,"$state":"/n"},"children":[]},"v2":{"type":"Text","props":{"content":"L (n = 2): **2s, 2p** → 2 + 6 = 8 electrons"},"visible":{"eq":2,"$state":"/n"},"children":[]},"v3":{"type":"Text","props":{"content":"M (n = 3): **3s, 3p, 3d** → 2 + 6 + 10 = 18 electrons"},"visible":{"eq":3,"$state":"/n"},"children":[]},"v4":{"type":"Text","props":{"content":"N (n = 4): **4s, 4p, 4d, 4f** → 2 + 6 + 10 + 14 = 32 electrons"},"visible":{"eq":4,"$state":"/n"},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["a","b"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","n","v1","v2","v3","v4","cols","t2"]}}},"title":"Open a level"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"2d","correct":true},{"id":"b","text":"4f","correct":false},{"id":"c","text":"3d","correct":false},{"id":"d","text":"2p","correct":false}],"question":"Which sublevel does NOT exist?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"The N level (n = 4) has ___ sublevels. The one that can hold 14 electrons is ___.","answers":[["4","four"],["4f","f"]],"mistakes":[{"id":"m1","blank":0,"answer":"3"},{"id":"m2","blank":1,"answer":"4d"},{"id":"m3","blank":1,"answer":"3f"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fb","q"]}}},"title":"Which sublevels exist?"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Main level n has n sublevels: 1s; 2s 2p; 3s 3p 3d; 4s 4p 4d 4f.","Maximum electrons: s 2, p 6, d 10, f 14.","The d sublevel first appears at n = 3 (3d)."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_tbl","ans_t"]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why there is a 3d sublevel but no 2d?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"Level n has n sublevels. 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In these elements the d sublevel fills, and it holds up to 10 electrons: one column for each electron."},{"id":"c","feedback":"Period 4 has 18 elements, not 10."}],"explanation":"In the middle block, the d sublevel is being filled, and a d sublevel holds up to 10 electrons: one column for each electron."}},"s2":{"trap":{"statement":"Every main energy level has all four sublevels: s, p, d and f.","correction":"Level n has only n sublevels. So there is no 2d: the d sublevel first appears at n = 3 (3d)."}},"s4":{"q":{"options":[{"id":"a","feedback":"Right. Level 2 has only 2 sublevels, 2s and 2p. The d sublevel first appears at n = 3."},{"id":"b","feedback":"Level 4 has 4 sublevels, so 4f exists."},{"id":"c","feedback":"Level 3 has 3 sublevels: 3s, 3p and 3d. So 3d exists. It is the one Ch.1 fills."},{"id":"d","feedback":"Level 2 has 2 sublevels, 2s and 2p, so 2p exists."}],"explanation":"2d does not exist: level 2 has two sublevels, 2s and 2p, and the d sublevel first appears at n = 3. 2p, 3d and 4f exist."},"fb":{"mistakes":[{"id":"m1","feedback":"You counted the sublevels of level 3. Level n has n sublevels, so the N level has as many sublevels as its n value."},{"id":"m2","feedback":"A d sublevel holds 10 electrons, not 14."},{"id":"m3","feedback":"There is no 3f. Level 3 has only 3 sublevels: s, p and d."}],"explanation":"N has 4s, 4p, 4d and 4f. The 4f sublevel holds up to 14 electrons."}},"s5":{"exam":{"body":"The d sublevel can take up to **ten electrons**, so the d block contains **ten vertical columns** (Ch.1 p.3).","title":"Back to the hook: exam wording"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"العناصر دي المعروف منها أكتر من 10 بكتير. الـ 10 دي جاية من جوه الذرة."},{"id":"b","feedback":"صح. في العناصر دي الـ d sublevel هو اللي بيتملي، وهو بيشيل لحد 10 electrons: عمود لكل electron."},{"id":"c","feedback":"الـ Period 4 فيه 18 عنصر، مش 10."}],"explanation":"في البلوك اللي في النص، الـ d sublevel هو اللي بيتملي، والـ d sublevel بيشيل لحد 10 electrons: عمود لكل electron."}},"s2":{"trap":{"statement":"كل main energy level فيه الـ sublevels الأربعة: s و p و d و f.","correction":"المستوى n فيه n sublevels تحديدًا. عشان كده مفيش 2d: الـ d sublevel أول ظهور ليه عند n = 3 (الـ 3d)."}},"s4":{"q":{"options":[{"id":"a","feedback":"صح. المستوى 2 فيه 2 sublevels تحديدًا: 2s والـ 2p. والـ d sublevel أول ظهور ليه عند n = 3."},{"id":"b","feedback":"المستوى 4 فيه 4 sublevels، يعني الـ 4f موجود."},{"id":"c","feedback":"المستوى 3 فيه 3 sublevels: 3s والـ 3p والـ 3d. يعني الـ 3d موجود، وهو اللي بيتملي في الفصل الأول."},{"id":"d","feedback":"المستوى 2 فيه 2 sublevels، 2s والـ 2p، يعني الـ 2p موجود."}],"explanation":"الـ 2d مش موجود: المستوى 2 فيه 2 sublevels، 2s و 2p، والـ d sublevel أول ظهور ليه عند n = 3. أما الـ 2p والـ 3d والـ 4f فموجودين."},"fb":{"mistakes":[{"id":"m1","feedback":"إنت عدّيت الـ sublevels بتوع المستوى 3. المستوى n فيه n sublevels، والـ n بتاع الـ N level مكتوب في السؤال."},{"id":"m2","feedback":"الـ 4d بيشيل 10 بس، مش 14."},{"id":"m3","feedback":"مفيش حاجة اسمها 3f. المستوى 3 فيه 3 sublevels تحديدًا: s و p و d."}],"explanation":"الـ N فيه الـ 4s والـ 4p والـ 4d والـ 4f. والـ 4f sublevel بيشيل لحد 14 electrons."}},"s5":{"exam":{"body":"الـ d sublevel بيشيل لحد **ten electrons**، عشان كده الـ d block فيه **ten vertical columns** (الفصل الأول ص.3).","title":"نرجع لسؤال البداية: صياغة الامتحان"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":7,"is_basics":true,"lesson_no":7,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-atom.sublevels","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Energy sublevels (s, p, d, f): from zero","duration_s":229.04,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-atom.sublevels","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Energy sublevels (s, p, d, f)","duration_s":44.47,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-atom.orbitals","kind":"lesson","version":3,"catalog_version":3,"ord":16,"primary_concept_id":"atom.orbitals","concepts":[{"concept_id":"atom.orbitals","role":"primary"}],"title":"Orbitals","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"5","correct":true},{"id":"b","text":"10","correct":false},{"id":"c","text":"2","correct":false}],"question":"How many orbitals does the d sublevel have?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Ch.1 fills 'the five orbitals of 3d' one electron at a time. Why five, and what is an orbital?"},"children":[]},"t2":{"type":"Text","props":{"content":"A d sublevel holds up to 10 electrons. One orbital holds at most 2. Predict:"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","t2","q"]}}},"title":"Why five?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 240 240\" xmlns=\"http://www.w3.org/2000/svg\"><circle cx=\"114.3\" cy=\"112.1\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"137.5\" cy=\"128.5\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"153.0\" cy=\"132.6\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"111.9\" cy=\"119.6\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"155.7\" cy=\"136.7\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"128.0\" cy=\"125.1\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"165.1\" cy=\"164.4\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"125.4\" cy=\"152.0\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"63.1\" cy=\"90.1\" r=\"1.6\" 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fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"175.2\" cy=\"143.8\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"98.4\" cy=\"161.9\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"130.1\" cy=\"118.7\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"112.2\" cy=\"203.6\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"185.1\" cy=\"158.0\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"110.8\" cy=\"84.5\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"96.0\" cy=\"128.3\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"117.2\" cy=\"117.3\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"102.0\" cy=\"85.1\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"119.5\" cy=\"119.2\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"173.3\" cy=\"170.8\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"104.4\" cy=\"113.0\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"101.4\" cy=\"139.1\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"120.0\" cy=\"121.9\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"120.7\" cy=\"145.2\" r=\"1.6\" fill=\"#60a5fa\" fill-opacity=\"0.8\"/><circle cx=\"120\" cy=\"120\" r=\"5\" fill=\"#f87171\"/></svg>","caption":"An s orbital. The dots show where the electron is likely to be: the denser, the more likely.","max_width":240},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["term","d","trap"]},"term":{"type":"KeyTerm","props":{"term_en":"Orbital","definition":"The region of space around the nucleus in which the electron is most likely to be found."},"children":[]},"trap":{"type":"Misconception","props":{},"children":[]}}},"title":"An orbital is a region, not a path"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\text{maximum electrons in a sublevel}\\\\ = 2 \\times \\text{number of orbitals}\\end{gathered}"},"children":[]},"t":{"type":"Text","props":{"content":"Each box is one orbital. Each orbital holds at most 2 electrons."},"children":[]},"eb":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"s","electrons":2},{"boxes":3,"label":"p","electrons":6},{"boxes":5,"label":"d","electrons":10}],"caption":"Full sublevels: s has 1 orbital (2 electrons), p has 3 (6), d has 5 (10)"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","eb","f"]}}},"title":"Orbitals in each sublevel"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"7","correct":true},{"id":"b","text":"14","correct":false},{"id":"c","text":"4","correct":false},{"id":"d","text":"28","correct":false}],"question":"The f sublevel holds up to 14 electrons. How many orbitals does it have?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"An orbital is the circular path an electron follows around the nucleus."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Count the orbitals"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["An orbital is a region where the electron is most likely to be found, not a path.","Orbitals: s 1, p 3, d 5, f 7.","At most 2 electrons per orbital, so d holds 5 × 2 = 10."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_eb","ans_t"]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why the 3d sublevel can hold 10 electrons?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"The 3d sublevel has 5 orbitals, and each orbital holds at most 2 electrons: 5 × 2 = 10."},"children":[]},"ans_eb":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"3d","electrons":10}],"caption":"A full 3d sublevel: 5 orbitals, 2 electrons each"},"children":[]}}},"title":"Summary"}],"title":"Orbitals","minutes":4,"book_ref":"Ch.1 p.8 relies on it ('gradual filling of the five orbitals of (3d) sublevel'); prerequisite from earlier grades","subtitle":"The five orbitals of the d sublevel","objectives":["Describe an orbital as a region around the nucleus where the electron is most likely to be found, not a circular path.","State the number of orbitals in s, p, d and f: 1, 3, 5 and 7.","Use 'at most two electrons per orbital' to find the maximum electrons in a sublevel."],"concept_ids":["atom.orbitals"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Yes: 10 electrons ÷ 2 per orbital = 5 orbitals."},{"id":"b","feedback":"That puts only one electron in each orbital, but an orbital can take two."},{"id":"c","feedback":"2 is how many electrons one orbital can take, not the number of orbitals."}],"explanation":"The d sublevel holds up to 10 electrons, and one orbital holds at most 2. So d has 10 ÷ 2 = 5 orbitals."}},"s2":{"trap":{"statement":"An orbital is a circular path (orbit) that the electron follows around the nucleus.","correction":"We cannot trace the exact path of an electron. We only know the region where it is most likely to be, so an orbital is drawn as a cloud."}},"s4":{"q":{"options":[{"id":"a","feedback":"Right: 14 ÷ 2 = 7 orbitals."},{"id":"b","feedback":"That puts one electron in each orbital. Each orbital can hold two."},{"id":"c","feedback":"4 is the level where f first appears (n = 4), not its number of orbitals."},{"id":"d","feedback":"That multiplies by 2. To get the orbitals, divide the electrons by 2."}],"explanation":"The f sublevel holds up to 14 electrons, 2 per orbital, so it has 14 ÷ 2 = 7 orbitals."},"tf":{"explanation":"Orbital = the region of space around the nucleus where the electron is most likely to be found.","feedback_true":"That describes an orbit, an older model. An orbital is a region where the electron is most likely to be found. Its exact path cannot be traced.","feedback_false":"Correct: an orbital is a region, not a path."}},"s5":{"exam":{"body":"Ch.1 p.8: the **five orbitals** of the (3d) sublevel are filled gradually, one electron in each orbital first (Hund's rule).","title":"Back to the hook"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"أيوه: 10 electrons ÷ 2 لكل orbital = 5 orbitals."},{"id":"b","feedback":"كده إنت حطيت electron واحد في كل orbital، لكن الـ orbital يقدر ياخد اتنين."},{"id":"c","feedback":"الـ 2 ده عدد الـ electrons اللي الـ orbital الواحد ياخدها، مش عدد الـ orbitals."}],"explanation":"الـ d sublevel بيشيل لحد 10 electrons، والـ orbital الواحد بيشيل 2 بالكتير. يبقى الـ d فيه 10 ÷ 2 = 5 orbitals."}},"s2":{"trap":{"statement":"الـ orbital ده مسار دايري (orbit) الـ electron بيلف فيه حوالين الـ nucleus.","correction":"إحنا مانقدرش نتتبع مسار الـ electron بالظبط. اللي نعرفه هو المنطقة اللي احتمال وجوده فيها أكبر، عشان كده الـ orbital بيترسم على شكل سحابة."}},"s4":{"q":{"options":[{"id":"a","feedback":"صح: 14 ÷ 2 = 7 orbitals."},{"id":"b","feedback":"كده إنت حطيت electron واحد في كل orbital. والـ orbital الواحد يقدر يشيل اتنين."},{"id":"c","feedback":"الـ 4 ده رقم المستوى اللي الـ f بيظهر فيه لأول مرة (n = 4)، مش عدد الـ orbitals بتاعته."},{"id":"d","feedback":"كده إنت ضربت في 2. عشان تجيب الـ orbitals، اقسم الـ electrons على 2."}],"explanation":"الـ f sublevel بيشيل لحد 14 electrons، 2 في الـ orbital الواحد، يبقى فيه 14 ÷ 2 = 7 orbitals."},"tf":{"explanation":"الـ Orbital = المنطقة اللي حوالين الـ nucleus اللي احتمال وجود الـ electron فيها أكبر ما يمكن.","feedback_true":"ده وصف الـ orbit، وده نموذج قديم. الـ orbital منطقة احتمال وجود الـ electron فيها أكبر ما يمكن، ومسار الـ electron بالظبط مانقدرش نتتبعه.","feedback_false":"مظبوط: الـ orbital منطقة، مش مسار."}},"s5":{"exam":{"body":"الفصل الأول ص.8: الـ **five orbitals** بتوع الـ (3d) sublevel بيتملوا بالتدريج، electron واحد في كل orbital الأول (الـ Hund's rule).","title":"نرجع لسؤال البداية"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":8,"is_basics":true,"lesson_no":8,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-atom.orbitals","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Orbitals: from zero","duration_s":212.67,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-atom.orbitals","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Orbitals","duration_s":50.05,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-atom.aufbau","kind":"lesson","version":4,"catalog_version":3,"ord":18,"primary_concept_id":"atom.aufbau","concepts":[{"concept_id":"atom.aufbau","role":"primary"}],"title":"Aufbau principle: the order of filling","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Into 3d","correct":false},{"id":"b","text":"Into 4s","correct":true},{"id":"c","text":"Into 4p","correct":false}],"question":"Predict:"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Argon's 18 electrons fill 1s, 2s, 2p, 3s and 3p. 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This gives the filling order.","max_width":380},"children":[]},"f":{"type":"Formula","props":{"latex":"\\begin{gathered}1s \\to 2s \\to 2p \\to 3s \\to 3p \\\\ \\to 4s \\to 3d \\to 4p\\end{gathered}","caption":"The filling order up to 4p"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["term","f","d"]},"term":{"type":"KeyTerm","props":{"term_en":"Aufbau principle (building-up principle)","definition":"Electrons fill the sublevels in order, starting with the lowest-energy sublevel, 1s."},"children":[]}}},"title":"The Aufbau principle"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"z":19},"elements":{"t":{"type":"Text","props":{"content":"[Ar] means argon's 18 electrons: $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6$. Change the atomic number from Ar to V and watch where each new electron goes."},"children":[]},"z":{"type":"Slider","props":{"max":23,"min":18,"step":1,"label":"Atomic number (Z)","value":{"$bindState":"/z"}},"children":[]},"t2":{"type":"Text","props":{"muted":true,"content":"From Sc to V, each new electron goes into 3d. Beyond V, Cr and Cu break this pattern; you will meet them in Ch.1."},"children":[]},"b18":{"type":"ElectronBoxes","props":{"groups":[{"boxes":3,"label":"3p","electrons":6}],"caption":"$_{18}\\text{Ar}$: $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6$"},"visible":{"eq":18,"$state":"/z"},"children":[]},"b19":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1}],"caption":"$_{19}\\text{K}$: $[\\text{Ar}]\\ 4s^1$"},"visible":{"eq":19,"$state":"/z"},"children":[]},"b20":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2}],"caption":"$_{20}\\text{Ca}$: $[\\text{Ar}]\\ 4s^2$"},"visible":{"eq":20,"$state":"/z"},"children":[]},"b21":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":1}],"caption":"$_{21}\\text{Sc}$: $[\\text{Ar}]\\ 4s^2\\ 3d^1$"},"visible":{"eq":21,"$state":"/z"},"children":[]},"b22":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":2}],"caption":"$_{22}\\text{Ti}$: $[\\text{Ar}]\\ 4s^2\\ 3d^2$"},"visible":{"eq":22,"$state":"/z"},"children":[]},"b23":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":3}],"caption":"$_{23}\\text{V}$: $[\\text{Ar}]\\ 4s^2\\ 3d^3$"},"visible":{"eq":23,"$state":"/z"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","z","b18","b19","b20","b21","b22","b23","t2","trap_tf"]},"trap_tf":{"type":"TrueFalse","props":{"answer":false,"statement":"3d fills before 4s, because 3 is less than 4."},"children":[]}}},"title":"Build the atoms from Ar to V"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"o":{"type":"Ordering","props":{"items":[{"id":"s3","text":"3s"},{"id":"p3","text":"3p"},{"id":"s4","text":"4s"},{"id":"d3","text":"3d"},{"id":"p4","text":"4p"}],"prompt":"Put these sublevels in the order they are filled."},"children":[]},"fb":{"type":"FillBlank","props":{"text":"Gallium (Z = 31) has 13 electrons after [Ar]. Write how many go into each sublevel: 4s ___, 3d ___, 4p ___.","answers":[["2"],["10"],["1"]],"mistakes":[{"id":"m1","blank":0,"answer":"1"},{"id":"m2","blank":0,"answer":"0"},{"id":"m3","blank":1,"answer":"11"},{"id":"m4","blank":1,"answer":"0"},{"id":"m5","blank":2,"answer":"11"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o","fb","h"]}}},"title":"Use the order"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Aufbau: electrons fill the sublevels in order, starting with 1s.","Order: 1s 2s 2p 3s 3p **4s 3d** 4p.","Back to the hook: electrons 19 and 20 go into 4s; 3d starts at Sc."]},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["$_{19}\\text{K}$","$[\\text{Ar}]\\ 4s^1$"],["$_{20}\\text{Ca}$","$[\\text{Ar}]\\ 4s^2$"],["$_{21}\\text{Sc}$","$[\\text{Ar}]\\ 4s^2\\ 3d^1$"]],"caption":"4s fills first (K, Ca); 3d starts at Sc","headers":["Element","Electronic configuration"]},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"next":{"type":"Callout","props":{"variant":"info"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tb","exam","next","self"]},"self":{"type":"Text","props":{"content":"Using calcium, can you explain why '3 comes before 4' is the wrong way to find the filling order?"},"children":[]}}},"title":"Summary"}],"title":"Aufbau principle: the order of filling","minutes":5,"book_ref":"Ch.1 p.4 and p.8 rely on it (calcium [Ar] 4s², then the 3d sublevel filled successively from Sc 4s² 3d¹ to Zn 4s² 3d¹⁰); prerequisite from earlier grades","subtitle":"Why 4s fills before 3d","objectives":["State the Aufbau principle and the filling order 1s 2s 2p 3s 3p 4s 3d 4p.","Use K and Ca as evidence that 4s is filled before 3d.","Use the filling order to share an atom's electrons between 4s, 3d and 4p."],"concept_ids":["atom.aufbau"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Level 3 is not full yet, so 3d looks like the next place. But the level number alone does not decide the order: in calcium, 3d has not started yet."},{"id":"b","feedback":"Right. Calcium is $[\\text{Ar}]\\ 4s^2$ (Ch.1 p.8). 3d starts filling only after 4s, at scandium."},{"id":"c","feedback":"4p comes later in the order, after 3d."}],"explanation":"Electrons 19 and 20 go into 4s. By the Aufbau principle, 4s fills before 3d, so calcium is $[\\text{Ar}]\\ 4s^2$; 3d starts filling at scandium."}},"s3":{"trap_tf":{"explanation":"The statement is false. The level number alone does not set the filling order: in K and Ca the new electrons go into 4s, and 3d starts filling only at Sc.","feedback_true":"Not so. The level number alone does not set the order: in K and Ca, the new electrons go into 4s, and 3d starts filling at Sc.","feedback_false":"Right. K and Ca put their new electrons into 4s; 3d starts filling at Sc."}},"s4":{"h":{"hints":["Follow the order: 4s, then 3d, then 4p.","In gallium, 4s and 3d fill to their maximum before 4p. Whatever is left goes to 4p."]},"o":{"items":[{"id":"s3","feedback":"On the diagonal arrows, 3s comes right after 2p."},{"id":"p3","feedback":"Argon's last electrons are in 3p, and 3p follows 3s on the same level."},{"id":"s4","feedback":"Calcium is $[\\text{Ar}]\\ 4s^2$ with 3d still empty, so 4s fills before 3d."},{"id":"d3","feedback":"The level number alone does not set the order: K and Ca put their new electrons into 4s while 3d was still empty."},{"id":"p4","feedback":"On the diagonal arrows, 4p comes right after 3d."}],"explanation":"3s → 3p → 4s → 3d → 4p."},"fb":{"mistakes":[{"id":"m1","feedback":"In gallium, 4s is filled before 3d starts, so 4s is completely full here."},{"id":"m2","feedback":"4s comes before 3d in the order, so it is filled first and is not empty in gallium."},{"id":"m3","feedback":"That is more than one d sublevel can hold; the extra electron goes on to 4p."},{"id":"m4","feedback":"3d comes before 4p in the order, so 3d fills before any electron reaches 4p."},{"id":"m5","feedback":"It looks like 3d was skipped. 3d comes before 4p, and the three sublevels together hold all 13 electrons."}],"explanation":"4s² (2) + 3d¹⁰ (10) + 4p¹ (1) = 13."}},"s5":{"exam":{"body":"After calcium $[\\text{Ar}]\\ 4s^2$, the sublevel (3d) is filled successively (Ch.1 p.4)."},"next":{"body":"When a transition metal forms an ion, it loses its 4s electrons first, because 4s is in the outermost level, n = 4 (Ch.1 p.9).","title":"Coming up in Ch.1"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"المستوى 3 لسه ماتملاش، فالـ 3d شكله المكان اللي عليه الدور. لكن رقم المستوى لوحده مش هو اللي بيحدد الترتيب: في الـ calcium، الـ 3d لسه مابدأش."},{"id":"b","feedback":"صح. الـ calcium هو $[\\text{Ar}]\\ 4s^2$ (الفصل الأول، ص 8). والـ 3d مش بيبدأ يتملي غير بعد الـ 4s، عند الـ scandium."},{"id":"c","feedback":"الـ 4p دوره بييجي بعدين في الترتيب، بعد الـ 3d."}],"explanation":"الـ electrons رقم 19 و 20 بيروحوا الـ 4s. حسب الـ Aufbau principle، الـ 4s بيتملي قبل الـ 3d، فالـ calcium هو $[\\text{Ar}]\\ 4s^2$؛ والـ 3d بيبدأ يتملي عند الـ scandium."}},"s3":{"trap_tf":{"explanation":"الجملة دي false. رقم المستوى لوحده مش هو اللي بيحدد ترتيب الملء: في الـ K والـ Ca الـ electrons الجديدة بتروح الـ 4s، والـ 3d مابيبدأش يتملي غير عند الـ Sc.","feedback_true":"لأ. رقم المستوى لوحده مش هو اللي بيحدد الترتيب: في الـ K والـ Ca، الـ electrons الجديدة بتروح الـ 4s، والـ 3d بيبدأ يتملي عند الـ Sc.","feedback_false":"صح. الـ K والـ Ca بيحطوا الـ electrons الجديدة في الـ 4s، والـ 3d بيبدأ يتملي عند الـ Sc."}},"s4":{"h":{"hints":["امشي على الترتيب: 4s وبعدين 3d وبعدين 4p.","في الـ gallium، الـ 4s والـ 3d بيتملوا لآخرهم قبل الـ 4p. واللي يفضل يروح للـ 4p."]},"o":{"items":[{"id":"s3","feedback":"على الأسهم المايلة، الـ 3s هو اللي بييجي على طول بعد الـ 2p."},{"id":"p3","feedback":"آخر electrons في الـ Ar موجودة في الـ 3p، والـ 3s بيتملي قبله."},{"id":"s4","feedback":"الـ calcium هو $[\\text{Ar}]\\ 4s^2$ والـ 3d لسه فاضي، يعني الـ 4s بيتملي قبل الـ 3d."},{"id":"d3","feedback":"رقم المستوى لوحده مش هو اللي بيحدد الترتيب: الـ K والـ Ca حطوا الـ electrons الجديدة في الـ 4s والـ 3d لسه فاضي."},{"id":"p4","feedback":"على الأسهم المايلة، الـ 4p بييجي بعد الـ 3d على طول."}],"explanation":"الترتيب: 3s → 3p → 4s → 3d → 4p."},"fb":{"mistakes":[{"id":"m1","feedback":"في الـ gallium، الـ 4s بيتملي على الآخر قبل ما الـ 3d يبدأ، والـ s sublevel المليان بيشيل أكتر من electron واحد."},{"id":"m2","feedback":"الـ 4s قبل الـ 3d في الترتيب، فبيتملي الأول ومش بيفضل فاضي."},{"id":"m3","feedback":"ده أكتر من اللي d sublevel واحد يقدر يشيله."},{"id":"m4","feedback":"الـ 3d قبل الـ 4p في الترتيب. ماتنطّهوش."},{"id":"m5","feedback":"شكلك نطّيت الـ 3d: الـ 3d قبل الـ 4p، والمجموع 4s + 3d + 4p لازم يطلع 13."}],"explanation":"المجموع: 4s² (2) + 3d¹⁰ (10) + 4p¹ (1) = 13."}},"s5":{"exam":{"body":"بعد الـ calcium $[\\text{Ar}]\\ 4s^2$، الـ sublevel (3d) بيتملي successively، يعني واحد ورا التاني (Ch.1 p.4)."},"next":{"body":"لما الـ transition metal يكوّن ion، بيفقد الـ 4s electrons الأول، عشان الـ 4s موجود في الـ outermost level، n = 4 (Ch.1 p.9).","title":"جاي في الفصل الأول"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":9,"is_basics":true,"lesson_no":9,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-atom.aufbau","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Aufbau principle (order of filling): from zero","duration_s":334.08,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-atom.aufbau","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Aufbau principle (order of filling)","duration_s":52.43,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 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Hold it near an aluminum soda can, and nothing happens."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Metal, but not pulled"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"The field is invisible. 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Like poles repel.","max_width":380},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t1","pic","rule","t2"]},"rule":{"type":"Callout","props":{"variant":"info"},"children":[]}}},"title":"Poles: pull or push"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"nail","text":"iron nail"},{"id":"clip","text":"steel paper clip"},{"id":"co","text":"a piece of cobalt"},{"id":"cu","text":"copper wire"},{"id":"al","text":"aluminum foil"},{"id":"au","text":"gold ring"}],"answer":{"no":["cu","al","au"],"pull":["nail","clip","co"]},"prompt":"Bring an ordinary magnet near each object. Sort them.","categories":[{"id":"pull","label":"Pulled strongly"},{"id":"no","label":"Not noticeably pulled"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"They attract","correct":false},{"id":"b","text":"They repel","correct":true},{"id":"c","text":"Nothing, unless they touch","correct":false}],"question":"Two bar magnets lie end to end. The S pole of one faces the S pole of the other. What happens?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Pulled or not?"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["A magnet has a **magnetic field** around it: the region where its magnetic force acts.","Like poles repel; unlike poles attract.","A magnet strongly attracts iron, cobalt and nickel, not all metals."]},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["iron (and steel)","copper"],["cobalt","aluminum"],["nickel","gold, silver"]],"caption":"Being a metal is not enough to be pulled by a magnet","headers":["Pulled strongly by a magnet","Metals not noticeably pulled"]},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Words you'll meet"}},"children":[]},"next":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Where will you use it?"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tab","b","exam","next","self"]},"self":{"type":"Text","props":{"content":"Can you explain why a magnet pulls a steel door but not an aluminum can?"},"children":[]}}},"title":"Summary"}],"title":"Magnets and magnetic fields","minutes":4,"book_ref":"Prerequisite (preparatory science); used in Ch.1 '4-The Magnetic properties', pp.13-14","subtitle":"What you need for the magnetic properties in Chapter 1","objectives":["Describe the magnetic field around a magnet and the rule of the poles: like poles repel, unlike poles attract.","Name the materials a magnet attracts strongly (iron, cobalt, nickel) and explain why 'magnets attract all metals' is wrong.","Say what it means for a substance to be attracted to, or repelled by, an external magnetic field."],"concept_ids":["phys.magnetic-field"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Weight isn't the reason. A magnet can lift a heavy iron nail. The can is made of aluminum, a metal a magnet doesn't noticeably pull."},{"id":"b","feedback":"Right. Being a metal is not enough. Only some materials are strongly pulled by a magnet."},{"id":"c","feedback":"This is the idea 'magnets attract all metals'. It's very common, but copper and aluminum are metals a magnet doesn't noticeably pull."}],"explanation":"A magnet strongly attracts only some materials, such as iron, cobalt and nickel. Aluminum is a metal, but a magnet doesn't noticeably pull it, so the can is not pulled."}},"s2":{"tf":{"explanation":"A magnet strongly attracts iron, cobalt and nickel (and steel, which is mostly iron). Copper, aluminum, gold and silver are metals too, but a magnet doesn't noticeably pull them, so not all metals are attracted.","feedback_true":"That idea is wrong. A magnet strongly attracts **iron, cobalt and nickel**, and steel, which is mostly iron. Copper, aluminum, gold and silver are metals too, but an ordinary magnet doesn't noticeably pull them.","feedback_false":"Right. A magnet strongly attracts iron, cobalt and nickel (and steel, which is mostly iron). Copper, aluminum, gold and silver are metals it doesn't noticeably pull."}},"s3":{"rule":{"body":"**Like poles repel; unlike poles attract.**","title":"The rule of the poles"}},"s4":{"c":{"items":[{"id":"nail","feedback":"Iron is on the list of three metals a magnet strongly attracts."},{"id":"clip","feedback":"Steel is mostly iron, so the magnet acts on it as it does on iron."},{"id":"co","feedback":"Cobalt is on the list of three metals, with iron and nickel."},{"id":"cu","feedback":"Copper is a metal, but being a metal is not enough: copper is not on the list of three."},{"id":"al","feedback":"Aluminum is not on the list of three metals, as the soda can example showed."},{"id":"au","feedback":"Gold is a metal, yet not one a magnet pulls. 'All metals' is the trap here."}],"explanation":"A magnet strongly attracts iron (and steel), cobalt and nickel. Copper, aluminum and gold are metals it doesn't noticeably pull."},"q":{"options":[{"id":"a","feedback":"Attraction needs unlike poles, N facing S. Here S faces S: like poles, so they repel."},{"id":"b","feedback":"Correct: S and S are like poles, and like poles repel."},{"id":"c","feedback":"Magnets act on each other without touching. Their fields reach across the gap."}],"explanation":"S facing S means like poles, and like poles repel, so the two magnets push each other apart. Magnets act on each other across the gap without touching."}},"s5":{"exam":{"body":"Chapter 1 uses these words: a substance **attracts to the external magnetic field**, or it **repels the external magnetic field**."},"next":{"body":"Magnetic properties of transition elements, in Chapter 1."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الوزن مش هو السبب. الـ magnet يقدر يرفع مسمار iron تقيل. العلبة معمولة من aluminum، وده metal الـ magnet مش بيشده بشكل ملحوظ."},{"id":"b","feedback":"صح. إن الحاجة تبقى metal ده مش كفاية. فيه مواد معيّنة تحديدًا هي اللي الـ magnet بيشدها بقوة."},{"id":"c","feedback":"دي فكرة إن الـ magnets بتجذب كل الـ metals. فكرة منتشرة جدًا، لكن الـ copper والـ aluminum metals والـ magnet مش بيشدهم بشكل ملحوظ."}],"explanation":"الـ magnet بيجذب بقوة مواد معيّنة تحديدًا، زي الـ iron والـ cobalt والـ nickel. الـ aluminum metal، لكن الـ magnet مش بيشده بشكل ملحوظ، عشان كده العلبة مش بتتشد."}},"s2":{"tf":{"explanation":"الـ magnet بيجذب بقوة الـ iron والـ cobalt والـ nickel (والـ steel اللي أغلبه iron). الـ copper والـ aluminum والـ gold والـ silver metals برضه، لكن الـ magnet مش بيشدهم بشكل ملحوظ، يعني مش كل الـ metals بتتجذب.","feedback_true":"الفكرة دي غلط. الـ magnet بيجذب بقوة الـ **iron والـ cobalt والـ nickel**، والـ steel اللي أغلبه iron. الـ copper والـ aluminum والـ gold والـ silver metals برضه، لكن الـ magnet العادي مش بيشدهم بشكل ملحوظ.","feedback_false":"صح. الـ magnet بيجذب بقوة الـ iron والـ cobalt والـ nickel (والـ steel اللي أغلبه iron). أما الـ copper والـ aluminum والـ gold والـ silver فهي metals مش بيشدها بشكل ملحوظ."}},"s3":{"rule":{"body":"**الـ like poles بتتنافر، والـ unlike poles بتتجاذب.**","title":"قاعدة الـ poles"}},"s4":{"c":{"items":[{"id":"nail","feedback":"الـ iron واحد من التلات metals اللي في القايمة."},{"id":"clip","feedback":"الـ steel أغلبه iron، والـ iron واحد من التلات metals اللي في القايمة."},{"id":"co","feedback":"الـ cobalt واحد من التلات metals اللي في القايمة."},{"id":"cu","feedback":"الـ copper metal، لكن إنه metal ده مش كفاية: الـ copper مش من التلاتة اللي في القايمة."},{"id":"al","feedback":"افتكر علبة الكانز: الـ aluminum مش من التلات metals اللي في القايمة."},{"id":"au","feedback":"الـ gold metal، ومع كده مش من اللي الـ magnet بيشدها. والفخ هنا هو فكرة «كل الـ metals»."}],"explanation":"الـ magnet بيجذب بقوة الـ iron (والـ steel)، والـ cobalt والـ nickel. أما الـ copper والـ aluminum والـ gold فهي metals مش بيشدها بشكل ملحوظ."},"q":{"options":[{"id":"a","feedback":"التجاذب محتاج unlike poles، يعني N قصاد S. هنا الـ S قصاد الـ S: like poles، فبيتنافروا."},{"id":"b","feedback":"مظبوط: الـ S والـ S دول like poles، والـ like poles بتتنافر."},{"id":"c","feedback":"الـ magnets بتأثر على بعض من غير ما تلمس بعض. الـ fields بتاعتهم بتوصل عبر المسافة اللي بينهم."}],"explanation":"الـ S قصاد الـ S يبقوا like poles، والـ like poles بتتنافر، فالاتنين magnets بيزقّوا بعض بعيد. والـ magnets بتأثر على بعض عبر المسافة من غير ما تلمس بعض."}},"s5":{"exam":{"body":"الفصل الأول بيستخدم الكلمات دي: المادة **attracts to the external magnetic field**، أو **repels the external magnetic field**."},"next":{"body":"الـ magnetic properties بتاعة الـ transition elements، في الفصل الأول."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":10,"is_basics":true,"lesson_no":10,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-phys.magnetic-field","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Magnets and magnetic fields: from zero","duration_s":212.92,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-phys.magnetic-field","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Magnets and magnetic 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What happens to their magnetic effects?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Every electron behaves like a tiny magnet. What happens when two of them share one orbital?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Two tiny magnets in one box"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"An electron can spin in one of two directions. We draw them as $\\uparrow$ and $\\downarrow$."},"children":[]},"box":{"type":"ElectronBoxes","props":{"groups":[{"fill":["↑"],"boxes":1,"label":"one orbital"}],"caption":"One electron: the arrow shows its spin direction"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["recall","term","box","t","trap"]},"term":{"type":"KeyTerm","props":{"term_en":"spin","definition":"Each electron spins around its own axis. This spinning forms a magnetic field, so the electron behaves like a tiny magnet."},"children":[]},"trap":{"type":"Misconception","props":{},"children":[]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: an orbital is the region around the nucleus where an electron is most likely found."},"children":[]}}},"title":"Spin makes a tiny magnet"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"With opposite spins, the two tiny magnets point opposite ways. So their magnetic effects cancel."},"children":[]},"box":{"type":"ElectronBoxes","props":{"groups":[{"fill":["↑↓"],"boxes":1,"label":"one orbital"}],"caption":"$\\uparrow\\downarrow$: a pair with opposite spins"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["term","box","t"]},"term":{"type":"KeyTerm","props":{"term_en":"Pauli exclusion principle","definition":"One orbital holds two electrons at most, and they must have opposite spins ($\\uparrow\\downarrow$)."},"children":[]}}},"title":"The Pauli exclusion principle"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"n":1},"elements":{"t":{"type":"Text","props":{"content":"Add electrons to one orbital and watch what happens."},"children":[]},"b0":{"type":"ElectronBoxes","props":{"groups":[{"fill":[""],"boxes":1,"label":"one orbital"}],"caption":"An empty orbital"},"visible":{"eq":0,"$state":"/n"},"children":[]},"b1":{"type":"ElectronBoxes","props":{"groups":[{"fill":["↑"],"boxes":1,"label":"one orbital"}],"caption":"$\\uparrow$: one **unpaired** electron. Its magnetic effect is not cancelled."},"visible":{"eq":1,"$state":"/n"},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"fill":["↑↓"],"boxes":1,"label":"one orbital"}],"caption":"$\\uparrow\\downarrow$: a **pair**. The two magnetic effects cancel."},"visible":{"eq":2,"$state":"/n"},"children":[]},"b3":{"type":"ElectronBoxes","props":{"groups":[{"fill":["↑↓"],"boxes":1,"label":"first orbital"},{"fill":["↑"],"boxes":1,"label":"next orbital"}],"caption":"The third electron can't join the pair. It goes to another orbital."},"visible":{"eq":3,"$state":"/n"},"children":[]},"no":{"type":"Callout","props":{"variant":"warning"},"visible":{"eq":3,"$state":"/n"},"children":[]},"sl":{"type":"Slider","props":{"max":3,"min":0,"step":1,"label":"Electrons added","value":{"$bindState":"/n"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","b0","b1","b2","b3","no","term"]},"term":{"type":"KeyTerm","props":{"term_en":"unpaired electron","definition":"An electron alone in its orbital ($\\uparrow$). Its magnetic effect is not cancelled."},"children":[]}}},"title":"Paired or unpaired?"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q1":{"type":"MCQ","props":{"options":[{"id":"a","text":"$[\\uparrow\\downarrow]$","correct":false},{"id":"b","text":"$[\\uparrow]$","correct":false},{"id":"c","text":"$[\\uparrow\\uparrow]$","correct":true}],"question":"Which orbital breaks the Pauli exclusion principle?"},"children":[]},"q2":{"type":"FillBlank","props":{"text":"The d sublevel has 5 orbitals. So it holds at most ___ electrons.","answers":[["10","ten"]],"mistakes":[{"id":"m1","blank":0,"answer":"5"},{"id":"m2","blank":0,"answer":"2"}]},"children":[]},"q3":{"type":"TrueFalse","props":{"answer":false,"statement":"In the orbital $[\\uparrow\\downarrow]$, the magnetic effects of the two electrons add up."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q1","q2","q3"]}}},"title":"Check yourself"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["A spinning electron behaves like a tiny magnet. $\\uparrow$ and $\\downarrow$ are its two spin directions.","Pauli: one orbital holds two electrons at most, with opposite spins ($\\uparrow\\downarrow$).","A pair's magnetic effects cancel. An **unpaired electron** keeps its effect."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_t"]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"next":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Where will you use it?"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","next","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why two electrons in the same orbital have no overall magnetic effect?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"The two electrons have opposite spins ($\\uparrow\\downarrow$). Their two tiny magnets point opposite ways, so their magnetic effects cancel."},"children":[]}}},"title":"Summary"}],"title":"Electron spin and the Pauli principle","minutes":4,"book_ref":"Prerequisite (G11 atomic structure); used in Ch.1 '4-The Magnetic properties' (spinning, ↑ and ↑↓), pp.13-14","subtitle":"Why paired electrons cancel and unpaired ones don't","objectives":["Explain that a spinning electron behaves like a tiny magnet, and that $\\uparrow$ and $\\downarrow$ show its two spin directions.","State the Pauli exclusion principle for one orbital: two electrons at most, with opposite spins ($\\uparrow\\downarrow$).","Explain why the magnetic effects of two paired electrons cancel, while an unpaired electron keeps its effect."],"concept_ids":["atom.electron-spin-pauli"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"That would need both electrons to spin the same way. Inside one orbital, they can't."},{"id":"b","feedback":"Right. In one orbital the two spins are opposite, so their magnetic effects cancel. Let's see why."},{"id":"c","feedback":"Electrons don't stop spinning. Each one keeps spinning, just opposite to its partner."}],"explanation":"The two electrons in one orbital spin in opposite directions, so their magnetic effects cancel. This is what the Pauli exclusion principle requires."}},"s2":{"trap":{"statement":"An electron drawn as $\\downarrow$ is a negative or missing electron.","correction":"$\\downarrow$ is a normal electron spinning the other way."}},"s4":{"no":{"body":"Not allowed in the same orbital: Pauli allows two electrons at most."}},"s5":{"q1":{"options":[{"id":"a","feedback":"This one is allowed: the two electrons have opposite spins, as the Pauli exclusion principle requires."},{"id":"b","feedback":"One electron alone is fine. It's just unpaired, so no rule is broken."},{"id":"c","feedback":"Right: two electrons in one orbital must have opposite spins. Same spins are not allowed."}],"explanation":"$[\\uparrow\\uparrow]$ breaks the Pauli exclusion principle: two electrons in one orbital must have opposite spins. $[\\uparrow\\downarrow]$ follows it, and one unpaired electron, $[\\uparrow]$, breaks no rule."},"q2":{"mistakes":[{"id":"m1","feedback":"You counted the orbitals, not the electrons. Each orbital holds a pair of electrons."},{"id":"m2","feedback":"That's the limit for one orbital, and the d sublevel has 5 orbitals."}],"explanation":"5 orbitals × 2 electrons each = 10 electrons."},"q3":{"explanation":"In $[\\uparrow\\downarrow]$ the two electrons have opposite spins, so their magnetic effects cancel. Adding up would need the same spin, which the Pauli exclusion principle does not allow in one orbital.","feedback_true":"Adding up would need the same spin. By the Pauli exclusion principle, the two electrons in one orbital have opposite spins, so their magnetic effects cancel.","feedback_false":"Correct: the spins are opposite, so the two magnetic effects cancel."}},"s6":{"exam":{"body":"Unpaired electrons ($\\uparrow$) form a magnetic field **due to their spinning**.","title":"Book wording you'll meet"},"next":{"body":"Magnetic properties of transition elements, in Chapter 1."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"ده كان هيحتاج إن الـ electrons الاتنين يعملوا spin في نفس الاتجاه. وجوه orbital واحد ماينفعش."},{"id":"b","feedback":"صح. في الـ orbital الواحد الـ spins الاتنين عكس بعض، فالتأثير المغناطيسي بتاعهم بيلغي بعضه. تعالى نشوف ليه."},{"id":"c","feedback":"الـ electrons مابتبطّلش spin. كل واحد بيفضل يعمل spin، إنما عكس اتجاه شريكه."}],"explanation":"الـ electrons الاتنين اللي في orbital واحد بيعملوا spin في اتجاهين عكس بعض، فالتأثير المغناطيسي بتاعهم بيلغي بعضه. وده اللي الـ Pauli exclusion principle بيطلبه."}},"s2":{"trap":{"statement":"الـ $\\downarrow$ معناه electron negative أو electron ناقص.","correction":"الـ $\\downarrow$ ده electron عادي خالص، كل الحكاية إنه بيعمل spin في الاتجاه التاني."}},"s4":{"no":{"body":"ماينفعش في نفس الـ orbital: الـ Pauli بيسمح باتنين electrons كحد أقصى."}},"s5":{"q1":{"options":[{"id":"a","feedback":"ده مسموح: الـ electrons الاتنين ليهم opposite spins، وده اللي الـ Pauli exclusion principle بيطلبه."},{"id":"b","feedback":"electron واحد لوحده مفيهوش مشكلة. هو مجرد unpaired، فمفيش قاعدة اتكسرت."},{"id":"c","feedback":"صح: اتنين electrons في orbital واحد لازم يكون ليهم opposite spins. نفس الـ spin مش مسموح."}],"explanation":"الـ $[\\uparrow\\uparrow]$ هو اللي بيكسر الـ Pauli exclusion principle: اتنين electrons في orbital واحد لازم يكون ليهم opposite spins. الـ $[\\uparrow\\downarrow]$ ماشي عليه، والـ unpaired electron الواحد، $[\\uparrow]$، مش بيكسر أي قاعدة."},"q2":{"mistakes":[{"id":"m1","feedback":"إنت عدّيت الـ orbitals، مش الـ electrons، والـ orbital الواحد بيساع 2 electrons."},{"id":"m2","feedback":"ده الحد الأقصى للـ orbital الواحد بس، والـ d فيه 5 orbitals."}],"explanation":"5 orbitals × 2 electrons في الواحد = 10 electrons."},"q3":{"explanation":"في الـ $[\\uparrow\\downarrow]$ الـ electrons الاتنين ليهم opposite spins، فالتأثيرين المغناطيسيين بيلغوا بعض. عشان يتجمعوا كان لازم نفس الـ spin، وده الـ Pauli exclusion principle مابيسمحش بيه في orbital واحد.","feedback_true":"عشان يتجمعوا، لازم يبقى ليهم نفس الـ spin. لكن حسب الـ Pauli exclusion principle، الـ electrons الاتنين في الـ orbital الواحد ليهم opposite spins، فالتأثيرين المغناطيسيين بيلغوا بعض.","feedback_false":"مظبوط: الـ spins عكس بعض، فالتأثيرين المغناطيسيين بيلغوا بعض."}},"s6":{"exam":{"body":"الـ unpaired electrons ($\\uparrow$) بتكوّن magnetic field **بسبب الـ spinning بتاعها**.","title":"صياغة الكتاب اللي هتقابلها"},"next":{"body":"هتستخدمها في الـ magnetic properties بتاعة الـ transition elements، في الفصل الأول."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":11,"is_basics":true,"lesson_no":11,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-atom.electron-spin-pauli","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Electron spin and the Pauli principle: from zero","duration_s":278.81,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-atom.electron-spin-pauli","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Electron spin and the Pauli principle","duration_s":47.37,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic 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2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.lesson-atom.electron-configuration-writing","kind":"lesson","version":4,"catalog_version":3,"ord":24,"primary_concept_id":"atom.electron-configuration-writing","concepts":[{"concept_id":"atom.electron-configuration-writing","role":"primary"}],"title":"Writing electronic configurations","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{_{20}Ca}:\\ 1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6 \\\\ 4s^2\\end{gathered}"},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$1s^2\\ 2s^2\\ 2p^6$","correct":false},{"id":"b","text":"$1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6$","correct":true},{"id":"c","text":"$4s^2$","correct":false}],"question":"Predict: which part of this line is exactly the configuration of argon, $\\ce{_{18}Ar}$?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Calcium has 20 electrons, so writing them all takes a long line. Is there a shortcut?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","f","q"]}}},"title":"A long line of electrons"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t1":{"type":"Text","props":{"content":"Fill the sublevels in the filling order you studied, starting with 1s. Fill one sublevel before you start the next. Chapter 1 shows two exceptions, Cr and Cu."},"children":[]},"chk":{"type":"Callout","props":{"variant":"tip"},"children":[]},"flow":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a"},{"to":"c","from":"b"},{"to":"d","from":"c"},{"to":"e","from":"d"},{"to":"f","from":"e"},{"to":"g","from":"f"}],"nodes":[{"id":"a","label":"1s (2)"},{"id":"b","label":"2s (2)"},{"id":"c","label":"2p (6)"},{"id":"d","label":"3s (2)"},{"id":"e","label":"3p (6)"},{"id":"f","label":"4s (2)"},{"id":"g","label":"3d (10)"}],"layout":"horizontal","caption":"Filling order, with the maximum number of electrons in each sublevel: s holds 2, p holds 6, d holds 10"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t1","flow","chk"]}}},"title":"The rules for writing"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Sulphur has 16 electrons. Let's place them, step by step."},"children":[]},"r1":{"type":"Reveal","props":{"label":"Step 1"},"children":["r1t"]},"r2":{"type":"Reveal","props":{"label":"Step 2"},"children":["r2t","r2f"]},"r3":{"type":"Reveal","props":{"label":"Step 3: the short form"},"children":["r3k","r3f"]},"r1t":{"type":"Text","props":{"content":"$1s^2\\ 2s^2\\ 2p^6$ uses 10 electrons. Why? Here, a sublevel is filled to its maximum before the next one starts."},"children":[]},"r2f":{"type":"Formula","props":{"latex":"\\ce{_{16}S}:\\ 1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^4","caption":"Check: 2 + 2 + 6 + 2 + 4 = 16"},"children":[]},"r2t":{"type":"Text","props":{"content":"6 electrons are left. 3s comes next and takes its 2. Then 3p takes the remaining 4."},"children":[]},"r3f":{"type":"Formula","props":{"latex":"\\ce{_{16}S}:\\ [\\text{Ne}]\\ 3s^2\\ 3p^4","caption":"Neon (Z = 10) is the noble gas just before sulphur"},"children":[]},"r3k":{"type":"KeyTerm","props":{"term_en":"noble-gas core","definition":"The configuration of the noble gas just before the element, written as its symbol in square brackets. Example: [Ne] = $1s^2\\ 2s^2\\ 2p^6$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","r1","r2","r3"]}}},"title":"Worked example: S (Z = 16)"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"q":{"type":"FillBlank","props":{"text":"Full: $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6$ 4s___ (type the exponent). In the short form, the noble-gas core is [___].","answers":[["1","one"],["Ar","argon"]],"mistakes":[{"id":"m1","blank":0,"answer":"2"},{"id":"m2","blank":1,"answer":"Ne"},{"id":"m3","blank":1,"answer":"Kr"}]},"children":[]},"t":{"type":"Text","props":{"content":"Potassium has 19 electrons. The first part is done for you."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q","h"]}}},"title":"Your turn: K (Z = 19)"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q1":{"type":"MCQ","props":{"options":[{"id":"a","text":"$[\\text{Ne}]\\ 3s^2\\ 3p^3$","correct":true},{"id":"b","text":"$[\\text{Ar}]\\ 3s^2\\ 3p^3$","correct":false},{"id":"c","text":"$[\\text{Ne}]\\ 3p^5$","correct":false},{"id":"d","text":"$[\\text{Ne}]\\ 3s^2\\ 3p^5$","correct":false}],"question":"Which is the short-form configuration of phosphorus, $\\ce{_{15}P}$?"},"children":[]},"q2":{"type":"FillBlank","props":{"text":"Short form of chlorine, $\\ce{_{17}Cl}$: [___] $3s^2$ 3p___ (type the core symbol, then the exponent).","answers":[["Ne","neon"],["5","five"]],"mistakes":[{"id":"m1","blank":0,"answer":"Ar"},{"id":"m2","blank":1,"answer":"7"},{"id":"m3","blank":1,"answer":"6"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q1","q2"]}}},"title":"On your own"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Fill the sublevels in the filling order: $1s\\ 2s\\ 2p\\ 3s\\ 3p\\ 4s\\ 3d$ … s holds 2, p holds 6, d holds 10.","Check: the exponents add up to Z.","Short form: [the noble gas just before the element] + the electrons after it, e.g. $\\ce{_{20}Ca}$: $[\\text{Ar}]\\ 4s^2$."]},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["$\\ce{_{16}S}$","$1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^4$","$[\\text{Ne}]\\ 3s^2\\ 3p^4$"],["$\\ce{_{19}K}$","$1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6\\ 4s^1$","$[\\text{Ar}]\\ 4s^1$"],["$\\ce{_{20}Ca}$","$1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6\\ 4s^2$","$[\\text{Ar}]\\ 4s^2$"]],"caption":"The examples of this lesson: full configuration and short form","headers":["Element","Full configuration","Short form"]},"children":[]},"next":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Where will you use it?"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tab","next","self"]},"self":{"type":"Text","props":{"content":"Can you explain how to check in a few seconds that $[\\text{Ne}]\\ 3s^2\\ 3p^4$ is sulphur?"},"children":[]}}},"title":"Summary"}],"title":"Writing electronic configurations","minutes":5,"book_ref":"Prerequisite (G11); used in Ch.1 'The Electronic Configurations and Oxidation states', p.8 (Ca: [Ar] 4s²)","subtitle":"Sublevel by sublevel, and the short form with [Ne] or [Ar]","objectives":["Write an atom's configuration sublevel by sublevel, in the filling order, so the electrons add up to Z.","Write the short form with a noble-gas core such as [Ne] or [Ar]."],"concept_ids":["atom.electron-configuration-writing"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"These exponents add up to only 10 electrons, and argon has 18."},{"id":"b","feedback":"Yes: 2 + 2 + 6 + 2 + 6 = 18. So Ca is argon's configuration plus $4s^2$."},{"id":"c","feedback":"$4s^2$ is only 2 electrons, and argon has 18."}],"explanation":"$1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6$ holds 2 + 2 + 6 + 2 + 6 = 18 electrons, exactly the configuration of argon. So calcium is argon's configuration plus $4s^2$."}},"s2":{"chk":{"body":"Quick check: the exponents must add up to the atomic number, Z."}},"s4":{"h":{"hints":["Add up the exponents already written.","Subtract that from 19 to see what is left for 4s.","For the core: which noble gas has that same number of electrons?"]},"q":{"mistakes":[{"id":"m1","feedback":"4s can hold 2, but after the 18 electrons already written only 1 is left for it (19 − 18 = 1)."},{"id":"m2","feedback":"[Ne] covers only 10 electrons, but 18 electrons are written before 4s."},{"id":"m3","feedback":"Krypton comes after potassium. The core is the noble gas just before the element."}],"explanation":"$\\ce{_{19}K}$: $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6\\ 4s^1$ = $[\\text{Ar}]\\ 4s^1$. Check: 18 + 1 = 19."}},"s5":{"q1":{"options":[{"id":"a","feedback":"Correct: 10 + 2 + 3 = 15, and neon is the noble gas just before P."},{"id":"b","feedback":"Argon (Z = 18) comes after phosphorus. The core must be the noble gas just before the element."},{"id":"c","feedback":"3s was skipped. In the filling order, 3s is filled before 3p."},{"id":"d","feedback":"These electrons add up to 10 + 2 + 5 = 17, not 15, so this is not phosphorus (Z = 15)."}],"explanation":"Phosphorus has 15 electrons, and the noble gas just before it is neon (10). So the short form is $[\\text{Ne}]\\ 3s^2\\ 3p^3$: 10 + 2 + 3 = 15, with 3s filled before 3p."},"q2":{"mistakes":[{"id":"m1","feedback":"Argon (Z = 18) comes after chlorine (Z = 17); the core is the noble gas just before the element."},{"id":"m2","feedback":"7 counts every electron after the core, but 3s already holds 2 of them."},{"id":"m3","feedback":"A full 3p would give 10 + 2 + 6 = 18 electrons, one more than chlorine's 17."}],"explanation":"$\\ce{_{17}Cl}$: $[\\text{Ne}]\\ 3s^2\\ 3p^5$. Check: 10 + 2 + 5 = 17."}},"s6":{"next":{"body":"Chapter 1 starts right after Ca, from Sc (Z = 21). Its short forms start with [Ar]."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الأُسس دي مجموعها يدوب 10 electrons، والـ argon عنده 18."},{"id":"b","feedback":"أيوه: 2 + 2 + 6 + 2 + 6 = 18. يعني الـ Ca هو configuration الـ argon ومعاه $4s^2$."},{"id":"c","feedback":"الـ $4s^2$ ده 2 electrons لا أكتر، والـ argon عنده 18."}],"explanation":"الجزء $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6$ فيه 2 + 2 + 6 + 2 + 6 = 18 electrons، وده configuration الـ argon بالظبط. يعني الـ calcium هو configuration الـ argon ومعاه $4s^2$."}},"s2":{"chk":{"body":"اختبار سريع: مجموع الأُسس لازم يساوي الـ atomic number، Z."}},"s4":{"h":{"hints":["اجمع الأُسس اللي اتكتبت خلاص.","اطرح الناتج من 19 عشان تعرف فاضل كام للـ 4s.","وبالنسبة للـ core: أنهي noble gas عنده نفس العدد ده من الـ electrons؟"]},"q":{"mistakes":[{"id":"m1","feedback":"الـ 4s يقدر يشيل 2، لكن بعد الـ 18 electron اللي اتكتبوا خلاص فاضل له electron واحد (19 − 18 = 1)."},{"id":"m2","feedback":"الـ [Ne] بيغطي 10 electrons لا أكتر، لكن المكتوب قبل الـ 4s هو 18 electron."},{"id":"m3","feedback":"الـ Krypton بييجي بعد الـ potassium. الـ core هو الـ noble gas اللي قبل العنصر على طول."}],"explanation":"$\\ce{_{19}K}$: $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6\\ 4s^1$ = $[\\text{Ar}]\\ 4s^1$. تشييك: 18 + 1 = 19."}},"s5":{"q1":{"options":[{"id":"a","feedback":"مظبوط: 10 + 2 + 3 = 15، والـ neon هو الـ noble gas اللي قبل الـ P على طول."},{"id":"b","feedback":"الـ Argon (Z = 18) بييجي بعد الـ phosphorus. والـ core لازم يكون الـ noble gas اللي قبل العنصر على طول."},{"id":"c","feedback":"الـ 3s اتنطّ. في ترتيب الملء، الـ 3s بيتملي قبل الـ 3p."},{"id":"d","feedback":"الـ electrons دي مجموعها 10 + 2 + 5 = 17، مش 15، يعني دي مش الـ phosphorus (Z = 15)."}],"explanation":"الـ phosphorus فيه 15 electrons، والـ noble gas اللي قبله على طول هو الـ neon (10). فالـ short form هو $[\\text{Ne}]\\ 3s^2\\ 3p^3$: 10 + 2 + 3 = 15، والـ 3s بيتملي قبل الـ 3p."},"q2":{"mistakes":[{"id":"m1","feedback":"الـ Argon (Z = 18) بييجي بعد الـ chlorine (Z = 17)؛ والـ core هو الـ noble gas اللي قبل العنصر على طول."},{"id":"m2","feedback":"الـ 7 دي كل الـ electrons اللي بعد الـ core، لكن الـ 3s شايل منهم 2 خلاص."},{"id":"m3","feedback":"لو الـ 3p اتملى هيبقى المجموع 10 + 2 + 6 = 18 electron، يعني واحد زيادة عن الـ 17 بتوع الـ chlorine."}],"explanation":"$\\ce{_{17}Cl}$: $[\\text{Ne}]\\ 3s^2\\ 3p^5$. تشييك: 10 + 2 + 5 = 17."}},"s6":{"next":{"body":"الفصل الأول بيبدأ على طول بعد الـ Ca، من الـ Sc (Z = 21). والـ short forms بتاعة عناصره بتبدأ بالـ [Ar]."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":12,"is_basics":true,"lesson_no":12,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-configuration","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Electronic configurations and oxidation states","duration_s":717.229,"start_s":26.7,"end_s":93.5,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-atom.electron-configuration-writing","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Writing electronic configurations","duration_s":50.03,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-pt.blocks","kind":"lesson","version":2,"catalog_version":3,"ord":26,"primary_concept_id":"pt.blocks","concepts":[{"concept_id":"pt.blocks","role":"primary"}],"title":"Blocks of the periodic table","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Its atomic mass","correct":false},{"id":"b","text":"The type of sublevel that receives its last electron","correct":true},{"id":"c","text":"Whether it is a metal or a nonmetal","correct":false}],"question":"Predict: what decides an element's region?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"The long form of the periodic table has four coloured regions. What puts an element in one region and not another?"},"children":[]},"pt":{"type":"PeriodicTable","props":{"caption":"The long form of the periodic table, coloured by block","show_legend":true},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","pt","q"]}}},"title":"Four coloured regions"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"pt":{"type":"PeriodicTable","props":{"labels":{"Cl":"3p⁵","Na":"3s¹"},"caption":"The s-block (left) and the p-block (right)","highlight_blocks":["s","p"]},"children":[]},"t1":{"type":"Text","props":{"content":"Sodium ends with $3s^1$, so it is in the s-block. Chlorine ends with $3p^5$, so it is in the p-block."},"children":[]},"t2":{"type":"Text","props":{"content":"The width fits the sublevel. s holds 2 electrons, so the s-block has 2 columns. p holds 6, so 6 columns."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["term","t1","pt","t2"]},"term":{"type":"KeyTerm","props":{"term_en":"block","definition":"A region of the table whose elements get their last electron in the same type of sublevel."},"children":[]}}},"title":"Blocks follow the last electron"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"t1":{"type":"Text","props":{"content":"The s- and p-blocks sit on both sides of the long form of the table. They hold the **representative elements** (groups IA to VIIA) and the **noble gases** (group 0)."},"children":[]},"t2":{"type":"Text","props":{"content":"Notice: for groups IA to VIIA, the Roman numeral counts the electrons in the outer level. The middle columns get different labels, which you'll meet in Chapter 1."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["s","IA",1,"$ns^1$"],["s","IIA",2,"$ns^2$"],["p","IIIA",13,"$ns^2\\ np^1$"],["p","IVA",14,"$ns^2\\ np^2$"],["p","VA",15,"$ns^2\\ np^3$"],["p","VIA",16,"$ns^2\\ np^4$"],["p","VIIA",17,"$ns^2\\ np^5$"],["p","0 (noble gases)",18,"$ns^2\\ np^6$ (He: $1s^2$)"]],"caption":"Groups of the s- and p-blocks (n = the period number)","headers":["Block","Group","Group number","Outer electrons end with"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t1","tab","t2"]}}},"title":"Groups of the s- and p-blocks"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"mg","text":"$\\ce{_{12}Mg}$: $[\\text{Ne}]\\ 3s^2$"},{"id":"k","text":"$\\ce{_{19}K}$: $[\\text{Ar}]\\ 4s^1$"},{"id":"n","text":"$\\ce{_{7}N}$: $1s^2\\ 2s^2\\ 2p^3$"},{"id":"br","text":"$\\ce{_{35}Br}$: $[\\text{Ar}]\\ 4s^2\\ 3d^{10}\\ 4p^5$"},{"id":"fe","text":"$\\ce{_{26}Fe}$: $[\\text{Ar}]\\ 4s^2\\ 3d^6$"},{"id":"zr","text":"$\\ce{_{40}Zr}$: $[\\text{Kr}]\\ 5s^2\\ 4d^2$"}],"answer":{"d":["fe","zr"],"p":["n","br"],"s":["mg","k"]},"prompt":"Sort each element by its block. First find the sublevel that receives the last electron.","categories":[{"id":"s","label":"s-block"},{"id":"p","label":"p-block"},{"id":"d","label":"d-block"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"p-block, group IIIA (13)","correct":true},{"id":"b","text":"s-block, group IIA (2)","correct":false},{"id":"c","text":"p-block, group IA (1)","correct":false},{"id":"d","text":"d-block, group IIIB (3)","correct":false}],"question":"Aluminum, $\\ce{_{13}Al}$, is $[\\text{Ne}]\\ 3s^2\\ 3p^1$. Which block and group is it in?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Find the block"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Block = the type of sublevel that receives the last electron.","The s- and p-blocks hold the representative elements (IA to VIIA) and the noble gases (group 0).","The d-block is in the middle; the f-block is the two rows at the bottom."]},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"Sodium ends with $3s^1$: its last electron enters an s sublevel, so it is in the s-block. Chlorine ends with $3p^5$: its last electron enters a p sublevel, so it is in the p-block. The block follows the type of sublevel, not the period."},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Book wording"}},"children":[]},"next":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Where will you use it?"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","next","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why Na and Cl are in different blocks, though both are in period 3?"},"children":[]}}},"title":"Summary"}],"title":"Blocks of the periodic table","minutes":4,"book_ref":"Prerequisite (G11); recalled in Ch.1 'The transition elements', p.3 ('(s) and (p) blocks ... on both sides of the long form of periodic table')","subtitle":"s, p, d and f: what puts an element in each region","objectives":["Explain that an element's block (s, p, d or f) is the type of sublevel that receives its last electron.","Locate the s- and p-blocks: the representative elements (groups IA to VIIA) and the noble gases (group 0)."],"concept_ids":["pt.blocks"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Mass rises along the table, but it doesn't split it into regions: the regions come from the electrons."},{"id":"b","feedback":"Yes. The regions are the s, p, d and f blocks, named after that sublevel."},{"id":"c","feedback":"The p-block has metals and nonmetals side by side, so being a metal or a nonmetal does not decide the region."}],"explanation":"An element's block is set by the type of sublevel that receives its last electron: s, p, d or f."}},"s4":{"c":{"items":[{"id":"mg","feedback":"The 3 is the level number, not the block; the letter of the last sublevel written decides it."},{"id":"k","feedback":"$[\\text{Ar}]$ is only the inner core; the block comes from the sublevel written after it."},{"id":"n","feedback":"The very last electron is not in $1s^2\\ 2s^2$; it is in the sublevel written at the end."},{"id":"br","feedback":"The very last electron is not in $3d^{10}$; it is in the sublevel written after it."},{"id":"fe","feedback":"$4s^2$ isn't the end of this configuration; the last electron goes into the sublevel written after it."},{"id":"zr","feedback":"$5s^2$ isn't the end here, and the period doesn't decide the block; the last sublevel written does."}],"explanation":"The block is the letter of the sublevel that receives the last electron: s, p or d."},"q":{"options":[{"id":"a","feedback":"Correct: the last electron enters 3p, and the outer level has 2 + 1 = 3 electrons."},{"id":"b","feedback":"The last electron did not go into $3s^2$; it entered the sublevel written after it."},{"id":"c","feedback":"The A label counts all the outer electrons in $3s^2\\ 3p^1$, s and p, not only the s electrons."},{"id":"d","feedback":"B labels belong to the middle (d) block, and Al has no d electron at the end."}],"explanation":"The last electron of aluminum enters 3p, so it is in the p-block. Its outer level holds 2 + 1 = 3 electrons, so it is in group IIIA (13)."}},"s5":{"exam":{"body":"Elements of the **(s) and (p) blocks** are found **on both sides of the long form of the periodic table**."},"next":{"body":"Chapter 1 starts with the elements between the s- and p-blocks."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ atomic mass بتزيد على طول الجدول، لكنها مش بتقسمه لمناطق. فكّر في الـ electrons بدل كده."},{"id":"b","feedback":"أيوه. المناطق دي هي الـ s و p و d و f blocks، وكل block متسمّي على اسم الـ sublevel ده."},{"id":"c","feedback":"الـ p-block فيه metals و nonmetals جنب بعض، فكون العنصر metal أو nonmetal مش هو اللي بيحدد المنطقة."}],"explanation":"الـ block بتاع العنصر بيتحدد بنوع الـ sublevel اللي بياخد آخر electron: s أو p أو d أو f."}},"s4":{"c":{"items":[{"id":"mg","feedback":"الـ 3 ده رقم المستوى، مش الـ block: الـ block بيتحدد من نوع آخر sublevel مكتوب."},{"id":"k","feedback":"الـ $[\\text{Ar}]$ ده مجرد الـ inner core، والـ block بيتحدد من الـ sublevel اللي بعده."},{"id":"n","feedback":"الـ configuration مكمّل بعد الـ $1s^2\\ 2s^2$، وآخر electron خالص في الـ sublevel اللي بعدهم."},{"id":"br","feedback":"يمكن إنت وقفت عند الـ $3d^{10}$، لكن آخر electron خالص بيدخل الـ sublevel اللي بعده."},{"id":"fe","feedback":"الـ $4s^2$ مش آخر الـ configuration ده: آخر electron بيدخل الـ sublevel اللي بعده."},{"id":"zr","feedback":"الـ $5s^2$ مش هو الآخر هنا، والـ period مش هو اللي بيحدد الـ block: آخر electron بيدخل الـ sublevel اللي بعده."}],"explanation":"الـ block هو حرف الـ sublevel اللي بياخد آخر electron: s أو p أو d."},"q":{"options":[{"id":"a","feedback":"مظبوط: آخر electron بيدخل الـ 3p، والمستوى الخارجي فيه 2 + 1 = 3 electrons."},{"id":"b","feedback":"إنت بصيت على الـ $3s^2$ لوحده، لكن آخر electron مش في الـ 3s."},{"id":"c","feedback":"الـ A label بيعدّ كل الـ electrons اللي في المستوى الخارجي، s و p، مش الـ s لوحدها: يعني كل الـ electrons اللي في الـ $3s^2\\ 3p^1$."},{"id":"d","feedback":"الـ B labels بتاعة الـ block اللي في النص (d)، والـ Al آخره مش d electron."}],"explanation":"آخر electron في الـ aluminum بيدخل الـ 3p، فهو في الـ p-block. والمستوى الخارجي فيه 2 + 1 = 3 electrons، فهو في group IIIA (13)."}},"s5":{"exam":{"body":"عناصر الـ **(s) and (p) blocks** موجودة **on both sides of the long form of the periodic table**، يعني على جانبين الجدول."},"next":{"body":"الفصل الأول بيبدأ بالعناصر اللي بين الـ s-block والـ p-block."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":13,"is_basics":true,"lesson_no":13,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-position","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"The transition elements and their series","duration_s":496.589,"start_s":22.6,"end_s":39.9,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-pt.blocks","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Blocks of the periodic table","duration_s":46.64,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te","section_title":"The transition elements","section_path":["Transition Elements","The transition elements"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","version":3,"catalog_version":3,"ord":28,"primary_concept_id":"te.position-in-periodic-table","concepts":[{"concept_id":"te.position-in-periodic-table","role":"primary"}],"title":"Transition elements in the periodic table","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"About 10: the famous metals","correct":false},{"id":"b","text":"About 20","correct":false},{"id":"c","text":"More than 60: more than half of the known elements","correct":true}],"question":"Predict: how many transition elements are there?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Iron, copper, gold, silver: you already know some transition elements. How many are there?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Just a few metals?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"So they're not a small club. They're the biggest part of the table."},"children":[]},"pt":{"type":"PeriodicTable","props":{"caption":"The transition elements: the middle of the table and the two rows at the bottom","show_legend":true,"highlight_blocks":["d","f"]},"children":[]},"book":{"type":"Text","props":{"content":"**The transition elements** occupy the middle of the periodic table between the (s) and (p) blocks. They include more than 60 elements, i.e. more than half the number of known elements."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["recall","pt","book","t"]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: the (s) and (p) blocks are on both sides of the long form of the table."},"children":[]}}},"title":"In the middle of the table"},{"id":"s3","kind":"interact","spec":{"root":"root","elements":{"r":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Check your answers"}},"children":["ans"]},"t":{"type":"Text","props":{"content":"Tap each highlighted element and read its block. Which ones are transition elements?"},"children":[]},"pt":{"type":"PeriodicTable","props":{"caption":"Ca, Fe, Ag, Nd, U and Ga","highlight_symbols":["Ca","Fe","Ag","Nd","U","Ga"]},"children":[]},"ans":{"type":"BulletList","props":{"items":["Ca: s-block. Not a transition element.","Fe and Ag: d-block, in the middle. Transition elements.","Nd and U: f-block, the two rows at the bottom. Nd is a **lanthanide** and U is an **actinide**. Transition elements too.","Ga: p-block. Not a transition element."]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","pt","r"]}}},"title":"Explore the table"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"c1":{"type":"Card","props":{"tone":"brand","title":"Main transition elements"},"children":["c1t"]},"c2":{"type":"Card","props":{"tone":"info","title":"Inner transition elements"},"children":["c2t"]},"pt":{"type":"PeriodicTable","props":{"caption":"Inner transition elements (f-block): the lanthanides and the actinides","highlight_blocks":["f"]},"children":[]},"c1t":{"type":"Text","props":{"content":"The **d-block**: the middle of the main table."},"children":[]},"c2t":{"type":"Text","props":{"content":"The **f-block**: the two rows at the bottom, the **lanthanides** and the **actinides**."},"children":[]},"book":{"type":"Text","props":{"content":"These elements can be classified into: 1- **Main transition elements**. 2- **Inner transition elements**. We'll study the main transition elements only."},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","cols","pt","trap"]},"trap":{"type":"Misconception","props":{},"children":[]}}},"title":"Two classes"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"ti","text":"Ti"},{"id":"ag","text":"Ag"},{"id":"ni","text":"Ni"},{"id":"ce","text":"Ce"},{"id":"nd","text":"Nd"},{"id":"u","text":"U"},{"id":"k","text":"K"},{"id":"br","text":"Br"}],"answer":{"main":["ti","ag","ni"],"none":["k","br"],"inner":["ce","nd","u"]},"prompt":"Sort each element.","categories":[{"id":"main","label":"Main transition (d-block)"},{"id":"inner","label":"Inner transition (f-block)"},{"id":"none","label":"Not a transition element"}]},"children":[]},"t":{"type":"Text","props":{"muted":true,"content":"Tap the table to check where each element is. Then sort."},"children":[]},"pt":{"type":"PeriodicTable","props":{"highlight_symbols":["Ti","Ag","Ni","Ce","Nd","U","K","Br"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","pt","c"]}}},"title":"Main, inner or neither?"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A main transition element (d-block)","correct":true},{"id":"b","text":"An inner transition element (f-block)","correct":false},{"id":"c","text":"A representative element of the p-block","correct":false},{"id":"d","text":"A representative element of the s-block","correct":false}],"question":"Element X is in period 5. It sits between strontium (group IIA, 2) and indium (group IIIA, 13). What is X?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"The transition elements are less than half of the known elements."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"A new case"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Transition elements occupy the middle of the periodic table between the (s) and (p) blocks.","They include more than 60 elements, i.e. more than half the number of known elements.","Main transition elements (d-block) and inner transition elements (f-block: lanthanides and actinides)."]},"children":[]},"rv":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Why transition elements are not a few famous metals"}},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"They include **more than 60 elements**, i.e. more than half the number of known elements: the whole middle of the table (d-block) plus the two rows at the bottom (f-block)."},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why 'transition elements are a few famous metals' is wrong?"},"children":[]}}},"title":"Summary"}],"title":"Transition elements in the periodic table","minutes":7,"book_ref":"Ch.1 'The transition elements', p.3 (periodic table figure, p.4)","subtitle":"Where they are, how many, and the two classes","objectives":["Locate the transition elements in the middle of the long form of the periodic table, between the (s) and (p) blocks.","State that they include more than 60 elements, i.e. more than half the number of known elements.","Classify them into main transition elements (d-block) and inner transition elements (f-block: lanthanides and actinides)."],"concept_ids":["te.position-in-periodic-table"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"That's the 'handful of metals' idea. Most transition elements aren't famous, but they fill the middle of the table."},{"id":"b","feedback":"Still too few: the transition elements fill the whole middle of the table, plus the two rows at the bottom."},{"id":"c","feedback":"Right. They fill the whole middle of the table, plus the two rows at the bottom."}],"explanation":"There are more than 60 transition elements, more than half the number of known elements. They fill the middle of the table between the (s) and (p) blocks, plus the two separate rows at the bottom."}},"s4":{"trap":{"statement":"Lanthanides and actinides are main transition elements, like the d-block ones.","correction":"Lanthanides and actinides are transition elements, but **inner** ones: they are in the f-block, not the d-block. So they are not the main transition elements this chapter studies."}},"s5":{"c":{"items":[{"id":"ti","feedback":"Ti sits in the middle of the main table, period 4, between the (s) and (p) blocks."},{"id":"ag","feedback":"Ag sits in the middle of the main table, period 5, between the (s) and (p) blocks."},{"id":"ni","feedback":"Ni sits in the middle of the main table, period 4, between the (s) and (p) blocks."},{"id":"ce","feedback":"Ce is in the first bottom row, with the lanthanides, one of the two separate rows at the bottom of the table."},{"id":"nd","feedback":"Nd is a lanthanide, in the two separate rows at the bottom of the table."},{"id":"u","feedback":"U is an actinide, in the last of the two separate rows at the bottom of the table."},{"id":"k","feedback":"K is in group IA, on the left side: the s-block, not between the (s) and (p) blocks."},{"id":"br","feedback":"Br is in group VIIA, on the right side: the p-block, not the middle of the table."}],"explanation":"Ti, Ag, Ni: d-block, main. Ce, Nd, U: f-block (lanthanides and actinides), inner. K (s-block) and Br (p-block) are not transition elements."}},"s6":{"q":{"options":[{"id":"a","feedback":"Right: between the (s) and (p) blocks of the main table lies the d-block, the main transition elements."},{"id":"b","feedback":"Inner transition elements are in the two separate rows at the bottom. X is inside period 5 of the main table."},{"id":"c","feedback":"The p-block starts at group IIIA (13), with indium. X comes before it."},{"id":"d","feedback":"The s-block ends at group IIA (2), with strontium. X comes after it."}],"explanation":"X is a main transition element. In period 5, the d-block lies between the s-block, which ends at Sr (group IIA), and the p-block, which starts at In (group IIIA)."},"tf":{"explanation":"The transition elements are more than 60 elements, i.e. more than half the number of known elements, not less than half.","feedback_true":"That's the 'handful of metals' idea, but the d-block and the two bottom rows together are a large part of the table.","feedback_false":"Correct: more than 60 elements, i.e. more than half the number of known elements."}},"s7":{"exam":{"body":"Transition elements: **more than 60 elements**, in the **middle** of the periodic table **between the (s) and (p) blocks**; classified into **main** and **inner** transition elements."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"دي فكرة إنهم «شوية metals معروفين». أغلب الـ transition elements مش مشهورة، لكنها موجودة ومالية نص الجدول."},{"id":"b","feedback":"لسه قليل: الـ transition elements مالية نص الجدول كله، ومعاه الصفين اللي تحت."},{"id":"c","feedback":"صح. هي مالية نص الجدول كله، ومعاه الصفين اللي تحت."}],"explanation":"الـ transition elements أكتر من 60 عنصر، يعني أكتر من نص عدد العناصر المعروفة. هي مالية نص الجدول بين الـ (s) والـ (p) blocks، ومعاه الصفين المنفصلين اللي تحت."}},"s4":{"trap":{"statement":"الـ lanthanides والـ actinides من الـ main transition elements، زيهم زي عناصر الـ d-block.","correction":"الـ lanthanides والـ actinides فعلًا transition elements، لكن **inner**: مكانهم في الـ f-block، مش الـ d-block. عشان كده هما مش من الـ main transition elements اللي الفصل ده بيدرسها."}},"s5":{"c":{"items":[{"id":"ti","feedback":"الـ Ti في نص الجدول الأساسي، في الـ period 4، بين الـ (s) والـ (p) blocks."},{"id":"ag","feedback":"الـ Ag قاعد في نص الجدول الأساسي، في الـ period 5، بين الـ (s) والـ (p) blocks."},{"id":"ni","feedback":"الـ Ni في نص الجدول الأساسي، في الـ period 4، بين الـ (s) والـ (p) blocks."},{"id":"ce","feedback":"الـ Ce في أول صف من الصفين المنفصلين اللي تحت الجدول، مع الـ lanthanides."},{"id":"nd","feedback":"الـ Nd ده lanthanide، في الصفين المنفصلين اللي تحت الجدول، مش في نص الجدول الأساسي."},{"id":"u","feedback":"الـ U ده actinide، في آخر صف من الصفين المنفصلين اللي تحت الجدول."},{"id":"k","feedback":"الـ K في الـ group IA، على الشمال في الـ s-block، مش بين الـ (s) والـ (p) blocks."},{"id":"br","feedback":"الـ Br في الـ group VIIA، على اليمين في الـ p-block، مش في نص الجدول."}],"explanation":"الـ Ti والـ Ag والـ Ni: من الـ d-block، يعني main. الـ Ce والـ Nd والـ U: من الـ f-block (الـ lanthanides والـ actinides)، يعني inner. أما الـ K (من الـ s-block) والـ Br (من الـ p-block) فمش transition elements."}},"s6":{"q":{"options":[{"id":"a","feedback":"صح: بين الـ (s) والـ (p) blocks في الجدول الأساسي بيقع الـ d-block، اللي هو الـ main transition elements."},{"id":"b","feedback":"الـ inner transition elements في الصفين المنفصلين اللي تحت. إنما X جوه الـ period 5 في الجدول الأساسي."},{"id":"c","feedback":"الـ p-block بيبدأ من الـ group IIIA (13)، بالـ indium. والـ X جاي قبله."},{"id":"d","feedback":"الـ s-block بيخلص عند الـ group IIA (2)، بالـ strontium. والـ X جاي بعده."}],"explanation":"الـ X ده main transition element. في الـ period 5، الـ d-block بيقع بين الـ s-block اللي بيخلص عند الـ Sr (الـ group IIA)، والـ p-block اللي بيبدأ من الـ In (الـ group IIIA)."},"tf":{"explanation":"الـ transition elements أكتر من 60 عنصر، يعني أكتر من نص عدد العناصر المعروفة، مش أقل من النص.","feedback_true":"دي فكرة إنهم «شوية metals معروفين»، لكن الـ d-block والصفين اللي تحت مع بعض جزء كبير من الجدول.","feedback_false":"مظبوط: أكتر من 60 عنصر، يعني أكتر من نص العناصر المعروفة."}},"s7":{"exam":{"body":"الـ transition elements: **أكتر من 60 عنصر**، في **نص** الـ periodic table **بين الـ (s) والـ (p) blocks**؛ وبتتقسم لـ **main** و**inner** transition 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That's eight labels."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Eight labels, how many columns?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"n":{"type":"Text","props":{"content":"Here n is the period number. For example, in period 4, $(n-1)d$ is 3d."},"children":[]},"k1":{"type":"Card","props":{"tone":"brand","title":"First column"},"children":["k1b","k1f"]},"k2":{"type":"Card","props":{"tone":"brand","title":"Last column"},"children":["k2b","k2f"]},"k1b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"(n−1)d","electrons":1}]},"children":[]},"k1f":{"type":"Formula","props":{"latex":"ns^2\\ (n-1)d^1"},"children":[]},"k2b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"(n−1)d","electrons":10}]},"children":[]},"k2f":{"type":"Formula","props":{"latex":"ns^2\\ (n-1)d^{10}"},"children":[]},"book":{"type":"Text","props":{"content":"In the main transition elements, electrons occupy the d sublevel in sequence. Since the d sublevel can take up to ten electrons, it contains **ten vertical columns**."},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["k1","k2"]},"note":{"type":"Callout","props":{"variant":"info"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","cols","n","note"]}}},"title":"Ten columns for ten d electrons"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"c":1},"elements":{"t":{"type":"Text","props":{"content":"Slide across the ten columns, from left to right. Watch the group label."},"children":[]},"n1":{"type":"Text","props":{"content":"**(3) IIIB**: the first column. Example: Sc."},"visible":{"eq":1,"$state":"/c"},"children":[]},"n2":{"type":"Text","props":{"content":"**(4) IVB**. Example: Ti."},"visible":{"eq":2,"$state":"/c"},"children":[]},"n3":{"type":"Text","props":{"content":"**(5) VB**. Example: V."},"visible":{"eq":3,"$state":"/c"},"children":[]},"n4":{"type":"Text","props":{"content":"**(6) VIB**. Example: Cr, one of the elements that differ slightly from the pattern."},"visible":{"eq":4,"$state":"/c"},"children":[]},"n5":{"type":"Text","props":{"content":"**(7) VIIB**. Example: Mn."},"visible":{"eq":5,"$state":"/c"},"children":[]},"n6":{"type":"Text","props":{"content":"**(8) VIII**: the first of its three columns. Example: Fe."},"visible":{"eq":6,"$state":"/c"},"children":[]},"n7":{"type":"Text","props":{"content":"**(9) VIII**: the second column of the same group. Example: Co."},"visible":{"eq":7,"$state":"/c"},"children":[]},"n8":{"type":"Text","props":{"content":"**(10) VIII**: the third column of the same group. Example: Ni."},"visible":{"eq":8,"$state":"/c"},"children":[]},"n9":{"type":"Text","props":{"content":"**(11) IB**. Example: Cu, the other element that differs slightly from the pattern."},"visible":{"eq":9,"$state":"/c"},"children":[]},"pt":{"type":"PeriodicTable","props":{"labels":{"V":"VB","Co":"VIII","Cr":"VIB","Cu":"IB","Fe":"VIII","Mn":"VIIB","Ni":"VIII","Sc":"IIIB","Ti":"IVB","Zn":"IIB"},"caption":"The ten columns of the d-block; period 4 shows the group labels","highlight_groups":[3,4,5,6,7,8,9,10,11,12]},"children":[]},"sl":{"type":"Slider","props":{"max":10,"min":1,"step":1,"label":"Column of the d-block","value":{"$bindState":"/c"}},"children":[]},"n10":{"type":"Text","props":{"content":"**(12) IIB**. Example: Zn. From one point of view, IIB is not considered as transition elements."},"visible":{"eq":10,"$state":"/c"},"children":[]},"st1":{"type":"Stat","props":{"tone":"brand","label":"Group number","value":{"args":{"c":{"$state":"/c"},"expr":"c + 2","digits":0},"$computed":"calc"}},"children":[]},"st2":{"type":"Stat","props":{"tone":"info","label":"d electrons (general pattern)","value":{"args":{"c":{"$state":"/c"},"expr":"c","digits":0},"$computed":"calc"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","stats","n1","n2","n3","n4","n5","n6","n7","n8","n9","n10","pt"]},"stats":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["st1","st2"]}}},"title":"Walk across the d-block"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"So Fe, Co and Ni, side by side, are more alike than Fe and the elements below it."},"children":[]},"pt":{"type":"PeriodicTable","props":{"labels":{"Co":"VIII","Fe":"VIII","Ni":"VIII"},"caption":"Group VIII: columns (8), (9) and (10)","highlight_groups":[8,9,10]},"children":[]},"book":{"type":"Text","props":{"content":"Group (8) VIII contains **three vertical columns**: (8), (9), (10). They differ from the other (B) groups: these elements are **similar horizontally** more than the elements below them in the same column."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","pt","t","trap"]},"trap":{"type":"Misconception","props":{},"children":[]}}},"title":"Group VIII: three columns"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"q1":{"type":"MCQ","props":{"options":[{"id":"a","text":"VIII","correct":true},{"id":"b","text":"XB","correct":false},{"id":"c","text":"IIB","correct":false},{"id":"d","text":"IB","correct":false}],"question":"Palladium (Pd) is in column (10). Which group label does the book give this column?"},"children":[]},"q2":{"type":"FillBlank","props":{"text":"Technetium (Tc) is in period 5, group (7) VIIB. In the general pattern, its configuration ends with $5s^2\\ 4d^{x}$, where x = ___.","answers":[["5","five"]],"mistakes":[{"id":"m1","blank":0,"answer":"7"},{"id":"m2","blank":0,"answer":"2"},{"id":"m3","blank":0,"answer":"4"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q1","q2","h"]}}},"title":"Name the group"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Ni and Pd (Pd is below Ni in the same column)","correct":false},{"id":"b","text":"Ni and Co (side by side in group VIII)","correct":true},{"id":"c","text":"Ni and Pt (Pt is two rows below Ni)","correct":false}],"question":"According to the book, which pair is expected to be more similar?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Group VIII is a single vertical column."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Neighbours or the one below?"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["The d sublevel can take up to ten electrons, so the d-block has ten vertical columns.","Groups from left to right: (3) IIIB, (4) IVB, (5) VB, (6) VIB, (7) VIIB, (8) (9) (10) VIII, (11) IB, (12) IIB.","Group VIII = three columns, similar horizontally more than vertically.","From one point of view, IIB is not considered as transition elements."]},"children":[]},"tbl":{"type":"DataTable","props":{"rows":[["(3)","IIIB"],["(4)","IVB"],["(5)","VB"],["(6)","VIB"],["(7)","VIIB"],["(8)","VIII"],["(9)","VIII"],["(10)","VIII"],["(11)","IB"],["(12)","IIB"]],"caption":"Ten columns, eight group labels","headers":["Column","Group"],"highlight":[{"col":1,"row":5},{"col":1,"row":6},{"col":1,"row":7}]},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tbl","exam","self"]},"self":{"type":"Text","props":{"content":"Can you explain how eight group labels cover ten columns?"},"children":[]}}},"title":"Summary"}],"title":"Main transition elements (d-block)","minutes":8,"book_ref":"Ch.1 'The Main transition elements (elements of d-block)', p.3; group labels as in the table, p.8","subtitle":"Ten columns, eight group labels","objectives":["Explain why the d-block has ten vertical columns: the d sublevel can take up to ten electrons.","Name the groups from left to right: (3) IIIB, (4) IVB, (5) VB, (6) VIB, (7) VIIB, (8) (9) (10) VIII, (11) IB, (12) IIB.","Describe group VIII: three columns whose elements are similar horizontally more than the elements below them."],"concept_ids":["te.d-block-groups"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"That's the trap. One of the labels covers more than one column, and the columns follow how many electrons d can take."},{"id":"b","feedback":"Yes. The d sublevel can take up to ten electrons, so the block has ten columns. One label must cover three of them."},{"id":"c","feedback":"d has 5 orbitals, but each orbital holds 2 electrons. Columns follow the electrons, not the orbitals."}],"explanation":"The d-block has 10 vertical columns, because the d sublevel can hold up to 10 electrons. There are eight labels because group VIII covers three columns: (8), (9) and (10)."}},"s2":{"note":{"body":"This is the general pattern. A few elements, like Cr and Cu, differ slightly. They have their own lesson."}},"s4":{"trap":{"statement":"Group VIII is one column.","correction":"Group VIII is three columns: (8), (9) and (10). That's how eight labels cover ten columns."}},"s5":{"h":{"hints":["Group (3) IIIB has $d^1$.","In the pattern, each column to the right adds one d electron.","Count from group (3) to group (7)."]},"q1":{"options":[{"id":"a","feedback":"Right: columns (8), (9) and (10) all belong to group VIII."},{"id":"b","feedback":"There is no XB. The labels don't just follow the column number, because one label covers three columns."},{"id":"c","feedback":"IIB is the last column, (12), two columns after column (10)."},{"id":"d","feedback":"IB is column (11), one column after column (10)."}],"explanation":"Column (10) belongs to group VIII, which covers columns (8), (9) and (10). So palladium is in group VIII."},"q2":{"mistakes":[{"id":"m1","feedback":"You used the group number, but the first d column, group (3), has $d^1$, and each column after it adds one d electron."},{"id":"m2","feedback":"That's the number of 5s electrons. The blank asks for the 4d electrons."},{"id":"m3","feedback":"Close. Counting from group (3) as $d^1$, each column to the right adds one d electron, up to group (7)."}],"explanation":"Group (3) has $d^1$, so group (7) has $d^5$: Tc ends with $5s^2\\ 4d^5$."}},"s6":{"q":{"options":[{"id":"a","feedback":"In most B groups, a column shares properties, but group VIII is special: the book says its elements resemble each other horizontally more than down the column."},{"id":"b","feedback":"Correct: group VIII elements are similar horizontally more than the elements below them."},{"id":"c","feedback":"That's the same column again, just further down; group VIII elements resemble each other sideways more than down."}],"explanation":"Ni and Co are expected to be more similar. The book says group VIII elements are similar horizontally more than the elements below them in the same column."},"tf":{"explanation":"Group VIII is not a single column: it covers three vertical columns, (8), (9) and (10), between VIIB (7) and IB (11).","feedback_true":"That's the trap from the start of this lesson: between group (7) VIIB and group (11) IB there are three columns, (8), (9) and (10).","feedback_false":"Correct: group VIII has three columns: (8), (9) and (10)."}},"s7":{"exam":{"body":"Give reason: the d-block contains ten vertical columns. **Because the d sublevel can take up to ten electrons.**"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"دي بالظبط الفخ. فيه اسم من الأسماء دي بيغطي أكتر من column، والـ columns ماشية ورا عدد الـ electrons اللي الـ d بيشيلها، مش ورا عدد الأسماء."},{"id":"b","feedback":"أيوه. الـ d sublevel بيشيل لحد 10 electrons، فالـ block فيه 10 columns. يعني لازم فيه اسم واحد بيغطي تلاتة منهم."},{"id":"c","feedback":"الـ d فيه 5 orbitals، لكن كل orbital بيشيل 2 electrons. والـ columns ماشية ورا عدد الـ electrons، مش عدد الـ orbitals."}],"explanation":"الـ d-block فيه 10 columns رأسية، عشان الـ d sublevel بيشيل لحد 10 electrons. والأسماء تمانية عشان الـ group VIII بيغطي تلات columns: (8) و(9) و(10)."}},"s2":{"note":{"body":"دي القاعدة العامة. فيه عناصر قليلة، زي الـ Cr والـ Cu، بتختلف شوية، وليها درس لوحدها."}},"s4":{"trap":{"statement":"الـ group VIII ده column واحد.","correction":"الـ group VIII بيغطي تلات columns: (8) و(9) و(10). وكده الأسماء التمانية بتغطي العشر columns."}},"s5":{"h":{"hints":["الـ group (3) IIIB فيه $d^1$.","في القاعدة العامة، كل column على اليمين بيزوّد electron واحد في الـ d.","عِد من الـ group (3) لحد الـ group (7)."]},"q1":{"options":[{"id":"a","feedback":"صح: الـ columns (8) و(9) و(10) كلهم تبع الـ group VIII."},{"id":"b","feedback":"مفيش حاجة اسمها XB. الأسماء مش ماشية ورا رقم الـ column وخلاص: فيه اسم واحد بيغطي تلات columns."},{"id":"c","feedback":"الـ IIB ده آخر column، رقم (12)، مش الـ column (10)."},{"id":"d","feedback":"الـ IB ده column رقم (11)، والـ column (10) قبله، تبع اسم بيغطي تلات columns."}],"explanation":"الـ column (10) تبع الـ group VIII، اللي بيغطي الـ columns (8) و(9) و(10). يعني الـ palladium في الـ group VIII."},"q2":{"mistakes":[{"id":"m1","feedback":"إنت استخدمت رقم الـ group. أول d column، اللي هو الـ group (3)، فيه $d^1$، والعدد بيزيد واحد مع كل column بعده."},{"id":"m2","feedback":"ده عدد الـ 5s electrons. المطلوب في الفراغ هو عدد الـ 4d electrons."},{"id":"m3","feedback":"قرّبت، لكن العد بيبدأ بالـ group (3) على إنه $d^1$، وبيزيد واحد مع كل column لحد الـ group (7)."}],"explanation":"الـ group (3) فيه $d^1$، يبقى الـ group (7) فيه $d^5$: والـ Tc بيخلص بـ $5s^2\\ 4d^5$."}},"s6":{"q":{"options":[{"id":"a","feedback":"في أغلب الـ B groups، عناصر الـ column الواحد بتشترك في خواصها. لكن الـ group VIII حالة خاصة: الكتاب بيقول إن عناصره بتتشابه أفقيًا أكتر من رأسيًا."},{"id":"b","feedback":"مظبوط: عناصر الـ group VIII بتتشابه أفقيًا أكتر من العناصر اللي تحتها."},{"id":"c","feedback":"ده نفس الـ column تاني، لكن أبعد لتحت. في الـ group VIII التشابه أفقي، مش رأسي."}],"explanation":"الـ Ni والـ Co هما المتوقع يكونوا أشبه ببعض. الكتاب بيقول إن عناصر الـ group VIII بتتشابه أفقيًا أكتر من العناصر اللي تحتها في نفس الـ column."},"tf":{"explanation":"الـ group VIII مش column واحد: ده بيغطي تلات columns رأسية، (8) و(9) و(10)، بين الـ VIIB (7) والـ IB (11).","feedback_true":"ده نفس الفخ اللي في أول الدرس: بين الـ group (7) VIIB والـ group (11) IB فيه أكتر من column واحد.","feedback_false":"مظبوط: الـ group VIII فيه تلات columns: (8) و(9) و(10)."}},"s7":{"exam":{"body":"علّل: الـ d-block فيه عشر columns رأسية. **عشان الـ d sublevel بيشيل لحد عشرة electrons.**"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":2,"lesson_no":15,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-position","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"The transition elements and their series","duration_s":496.589,"start_s":98.9,"end_s":182.7,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.d-block-groups","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Main transition elements (d-block)","duration_s":45,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition 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Which sublevel does it fill?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Iron is in period 4, but its series fills the 3d sublevel. Why not 4d?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Period 4, but 3d?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\text{period } n \\;\\longrightarrow\\; (n-1)d","caption":"period 4 → 3d, period 5 → 4d, period 6 → 5d, period 7 → 6d"},"children":[]},"why":{"type":"Text","props":{"content":"Why one less? In the filling order, 3d comes after 4s. So 3d fills only in period 4, after 4s."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["term","f","why","trap"]},"term":{"type":"KeyTerm","props":{"term_en":"transition series","definition":"A horizontal series of main transition elements in which a d sublevel is filled successively."},"children":[]},"trap":{"type":"Misconception","props":{},"children":[]}}},"title":"Four horizontal series"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"s":1},"elements":{"t":{"type":"Text","props":{"content":"Slide through the four series."},"children":[]},"hg":{"type":"Callout","props":{"variant":"info"},"visible":{"eq":3,"$state":"/s"},"children":[]},"p1":{"type":"PeriodicTable","props":{"labels":{"Sc":"first","Zn":"last"},"highlight_symbols":["Sc","Ti","V","Cr","Mn","Fe","Co","Ni","Cu","Zn"]},"visible":{"eq":1,"$state":"/s"},"children":[]},"p2":{"type":"PeriodicTable","props":{"labels":{"Y":"first","Cd":"last"},"highlight_symbols":["Y","Zr","Nb","Mo","Tc","Ru","Rh","Pd","Ag","Cd"]},"visible":{"eq":2,"$state":"/s"},"children":[]},"p3":{"type":"PeriodicTable","props":{"labels":{"Hg":"last","La":"first"},"highlight_symbols":["La","Hf","Ta","W","Re","Os","Ir","Pt","Au","Hg"]},"visible":{"eq":3,"$state":"/s"},"children":[]},"p4":{"type":"PeriodicTable","props":{"highlight_symbols":["Rf","Db","Sg","Bh","Hs","Mt","Ds","Rg","Cn"]},"visible":{"eq":4,"$state":"/s"},"children":[]},"sl":{"type":"Slider","props":{"max":4,"min":1,"step":1,"label":"Transition series","value":{"$bindState":"/s"}},"children":[]},"x1":{"type":"Text","props":{"content":"**The first transition series**: period 4, the (3d) sublevel. Ten elements, from scandium $\\ce{_{21}Sc}$ $(4s^2\\ 3d^1)$ to zinc $\\ce{_{30}Zn}$ $(4s^2\\ 3d^{10})$. They come after calcium."},"visible":{"eq":1,"$state":"/s"},"children":[]},"x2":{"type":"Text","props":{"content":"**The second transition series**: period 5, the (4d) sublevel. Ten elements, from yttrium $\\ce{_{39}Y}$ $(5s^2\\ 4d^1)$ to cadmium $\\ce{_{48}Cd}$ $(5s^2\\ 4d^{10})$."},"visible":{"eq":2,"$state":"/s"},"children":[]},"x3":{"type":"Text","props":{"content":"**The third transition series**: period 6, the (5d) sublevel. Ten elements, from lanthanum $\\ce{_{57}La}$ $(6s^2\\ 5d^1)$ to mercury $\\ce{_{80}Hg}$ $(6s^2\\ 4f^{14}\\ 5d^{10})$. On this table, La sits in the bottom row."},"visible":{"eq":3,"$state":"/s"},"children":[]},"x4":{"type":"Text","props":{"content":"**The fourth transition series**: period 7, the (6d) sublevel."},"visible":{"eq":4,"$state":"/s"},"children":[]},"st1":{"type":"Stat","props":{"tone":"brand","label":"Period","value":{"args":{"s":{"$state":"/s"},"expr":"s + 3","digits":0},"$computed":"calc"}},"children":[]},"st2":{"type":"Stat","props":{"tone":"info","label":"Sublevel filled","value":{"args":{"s":{"$state":"/s"},"expr":"s + 2","digits":0,"template":"{}d"},"$computed":"calc"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","stats","x1","p1","x2","p2","x3","p3","x4","p4","hg"]},"stats":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["st1","st2"]}}},"title":"Explore each series"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"d":{"type":"Divider","props":{"label":"Your turn"},"children":[]},"q":{"type":"FillBlank","props":{"text":"Zirconium (Zr) is in period 5. It is in the ___ transition series, which fills the ___ sublevel.","answers":[["second","2nd","2"],["4d"]],"mistakes":[{"id":"m1","blank":0,"answer":"fifth"},{"id":"m2","blank":0,"answer":"first"},{"id":"m3","blank":1,"answer":"5d"},{"id":"m4","blank":1,"answer":"3d"}]},"children":[]},"t":{"type":"Text","props":{"content":"Gold (Au) is in period 6. Which series is it in?"},"children":[]},"r1":{"type":"Reveal","props":{"label":"Step 1: find the sublevel"},"children":["r1t"]},"r2":{"type":"Reveal","props":{"label":"Step 2: find the series"},"children":["r2t"]},"r1t":{"type":"Text","props":{"content":"Rule: in period n, the (n−1)d sublevel fills. Period 6 → $(6-1)d$ = 5d."},"children":[]},"r2t":{"type":"Text","props":{"content":"The 5d sublevel fills in the third transition series. So Au is in the third series."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","r1","r2","d","q"]}}},"title":"Find the series"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"ti","text":"Ti"},{"id":"co","text":"Co"},{"id":"mo","text":"Mo"},{"id":"ag","text":"Ag"},{"id":"w","text":"W"},{"id":"pt","text":"Pt"},{"id":"rf","text":"Rf"}],"answer":{"s1":["ti","co"],"s2":["mo","ag"],"s3":["w","pt"],"s4":["rf"]},"prompt":"Which transition series is each element in?","categories":[{"id":"s1","label":"1st (3d)"},{"id":"s2","label":"2nd (4d)"},{"id":"s3","label":"3rd (5d)"},{"id":"s4","label":"4th (6d)"}]},"children":[]},"t":{"type":"Text","props":{"muted":true,"content":"Tap the table to read each element's period. Then sort."},"children":[]},"pt":{"type":"PeriodicTable","props":{"highlight_symbols":["Ti","Co","Mo","Ag","W","Pt","Rf"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","pt","c"]}}},"title":"Sort into series"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q1":{"type":"MCQ","props":{"options":[{"id":"a","text":"Strontium, Sr","correct":false},{"id":"b","text":"Yttrium, Y","correct":true},{"id":"c","text":"Zirconium, Zr","correct":false},{"id":"d","text":"Scandium, Sc","correct":false}],"question":"Which element starts the second transition series?"},"children":[]},"q2":{"type":"MCQ","props":{"options":[{"id":"a","text":"It fills 3d: in period n, the (n−1)d sublevel fills","correct":true},{"id":"b","text":"It is in period 1, not period 4","correct":false},{"id":"c","text":"Nothing: period 4 fills 4d","correct":false}],"question":"A student writes: 'The first transition series fills 4d, because it is in period 4.' What is wrong?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q1","q2"]}}},"title":"First and last"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Four horizontal series. A d sublevel is filled successively: 3d (period 4), 4d (period 5), 5d (period 6), 6d (period 7).","1st: $\\ce{_{21}Sc}$ $(4s^2\\ 3d^1)$ to $\\ce{_{30}Zn}$ $(4s^2\\ 3d^{10})$. 2nd: $\\ce{_{39}Y}$ $(5s^2\\ 4d^1)$ to $\\ce{_{48}Cd}$ $(5s^2\\ 4d^{10})$.","3rd: $\\ce{_{57}La}$ $(6s^2\\ 5d^1)$ to $\\ce{_{80}Hg}$ $(6s^2\\ 4f^{14}\\ 5d^{10})$."]},"children":[]},"rv":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Why period 4 fills 3d, not 4d"}},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"In the filling order, 3d comes after 4s. So 3d fills only in period 4, after 4s: in period n, the (n−1)d sublevel fills."},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why the series in period 4 fills 3d, not 4d?"},"children":[]}}},"title":"Summary"}],"title":"The four transition series","minutes":8,"book_ref":"Ch.1 'The first ... fourth transition series', pp.4-5 (periodic table figure, p.4)","subtitle":"Which d sublevel fills in each period","objectives":["Name the four transition series and the sublevel filled successively in each: 3d, 4d, 5d, 6d.","Link each series to its period (4, 5, 6, 7): in period n, the (n−1)d sublevel is filled.","Name the first and last element of the first three series, with their configurations as in the book."],"concept_ids":["te.transition-series"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"That's the 'same number as the period' idea. The period-4 series fills 3d, not 4d. Apply the same shift to period 5."},{"id":"b","feedback":"Yes: one less than the period number. Let's see why."},{"id":"c","feedback":"5s fills at the start of period 5, in the s-block. The transition series fill a d sublevel."}],"explanation":"The second transition series fills 4d. In period n the (n−1)d sublevel fills, because in the filling order 3d comes after 4s and 4d comes after 5s."}},"s2":{"trap":{"statement":"The first transition series fills 4d because it is in period 4.","correction":"It fills **3d**: in period n, the (n−1)d sublevel fills. And it is in period 4, after calcium, not in period 1."}},"s3":{"hg":{"body":"Why $4f^{14}$ in Hg? The lanthanides, after La, fill the 4f sublevel. Hg keeps those 14 electrons."}},"s4":{"q":{"mistakes":[{"id":"m1","feedback":"Series and period numbers are not the same: the first series is in period 4, and Zr is in period 5."},{"id":"m2","feedback":"The first series is in period 4, and Zr is in period 5."},{"id":"m3","feedback":"That uses the period number for the d sublevel; the rule is $(n-1)d$ with Zr's period."},{"id":"m4","feedback":"3d belongs to period 4, and Zr is in period 5; the rule is $(n-1)d$."}],"explanation":"Period 5 → $(5-1)d$ = 4d, which fills in the second transition series."}},"s5":{"c":{"items":[{"id":"ti","feedback":"Ti is in period 4; its series follows the $(n-1)d$ sublevel of that period, not the period number."},{"id":"co","feedback":"Co is in period 4, right after Fe; its series follows the $(n-1)d$ sublevel of that period."},{"id":"mo","feedback":"Mo is in period 5; by $(n-1)d$ its sublevel is one number below its period."},{"id":"ag","feedback":"Ag is in period 5: series and period numbers differ, and its series follows the $(n-1)d$ sublevel of that period."},{"id":"w","feedback":"W is in period 6; its series follows the $(n-1)d$ sublevel of that period."},{"id":"pt","feedback":"Pt is in period 6, next to Au; its series follows the $(n-1)d$ sublevel of that period."},{"id":"rf","feedback":"Rf is in period 7; its series follows the $(n-1)d$ sublevel of that period."}],"explanation":"Period 4 → 3d (1st), period 5 → 4d (2nd), period 6 → 5d (3rd), period 7 → 6d (4th)."}},"s6":{"q1":{"options":[{"id":"a","feedback":"Sr is $5s^2$, with no d electron. It is in the s-block, group IIA."},{"id":"b","feedback":"Right: $\\ce{_{39}Y}$ $(5s^2\\ 4d^1)$ has the first 4d electron."},{"id":"c","feedback":"Zr has $4d^2$. One element before it already has a 4d electron."},{"id":"d","feedback":"Sc starts the first series, in period 4. The second series is one period lower."}],"explanation":"Yttrium, $\\ce{_{39}Y}$ $(5s^2\\ 4d^1)$, starts the second transition series: it is the first element of period 5 with a 4d electron."},"q2":{"options":[{"id":"a","feedback":"Correct: in the filling order 3d comes after 4s, so 3d fills in period 4."},{"id":"b","feedback":"Period 1 has only H and He, no d sublevel at all; the first series comes after calcium, in period 4."},{"id":"c","feedback":"That's the 'same number as the period' idea, but the first element, Sc, is $4s^2\\ 3d^1$."}],"explanation":"The first transition series fills 3d, not 4d: in period n the (n−1)d sublevel fills, because 3d comes after 4s in the filling order. Its first element, Sc, is $4s^2\\ 3d^1$."}},"s7":{"exam":{"body":"**The first transition series**: the elements in which the sublevel **(3d) is filled successively**. Found in the **fourth period after calcium**; ten elements, from scandium to zinc."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"دي فكرة «نفس رقم الـ period». الـ series اللي في الـ period 4 بتملا الـ 3d مش الـ 4d، ونفس الفرق ده بينطبق على الـ period 5."},{"id":"b","feedback":"أيوه: أقل من رقم الـ period بواحد. تعالى نشوف ليه."},{"id":"c","feedback":"الـ 5s بيتملي في أول الـ period 5، في الـ s-block. والـ transition series بتملا d sublevel."}],"explanation":"الـ second transition series بتملا الـ 4d. في الـ period n بيتملي الـ (n−1)d sublevel، عشان في ترتيب الملء الـ 3d بييجي بعد الـ 4s، والـ 4d بييجي بعد الـ 5s."}},"s2":{"trap":{"statement":"الـ first transition series بتملا الـ 4d عشان هي في الـ period 4.","correction":"هي بتملا الـ **3d**: في الـ period n بيتملي الـ (n−1)d sublevel. وهي في الـ period 4، بعد الـ calcium، مش في الـ period 1."}},"s3":{"hg":{"body":"ليه $4f^{14}$ في الـ Hg؟ الـ lanthanides، اللي بعد الـ La، بتملا الـ 4f sublevel، والـ Hg محتفظ بالـ 14 electrons دول."}},"s4":{"q":{"mistakes":[{"id":"m1","feedback":"رقم الـ series مش زي رقم الـ period: الـ first series في الـ period 4، والـ series بتزيد واحد مع كل period بعده."},{"id":"m2","feedback":"الـ first series في الـ period 4، لكن الـ Zr في الـ period 5."},{"id":"m3","feedback":"كده إنت استخدمت رقم الـ period للـ d sublevel، لكن القاعدة هي $(n-1)d$ مع الـ period بتاع الـ Zr."},{"id":"m4","feedback":"الـ 3d ده بتاع الـ period 4، والـ Zr في الـ period 5، والقاعدة هي $(n-1)d$."}],"explanation":"الـ period 5 → $(5-1)d$ = 4d، وده اللي بيتملي في الـ second transition series."}},"s5":{"c":{"items":[{"id":"ti","feedback":"الـ Ti في الـ period 4، وفي الـ period n بيتملي الـ $(n-1)d$ sublevel."},{"id":"co","feedback":"الـ Co في الـ period 4، بعد الـ Fe على طول، فهو في نفس الـ series بتاعة الـ Fe، اللي بتتبع الـ $(n-1)d$ sublevel بتاع الـ period ده."},{"id":"mo","feedback":"الـ Mo في الـ period 5، والـ sublevel بتاعه بييجي من القاعدة $(n-1)d$، ومنه بتتحدد الـ series."},{"id":"ag","feedback":"الـ Ag في الـ period 5، ورقم الـ series غير رقم الـ period: الـ series بتاعته بتتبع الـ $(n-1)d$ sublevel بتاع الـ period ده."},{"id":"w","feedback":"الـ W في الـ period 6، وفي الـ period n بيتملي الـ $(n-1)d$ sublevel."},{"id":"pt","feedback":"الـ Pt في الـ period 6، وفي الـ period n بيتملي الـ $(n-1)d$ sublevel."},{"id":"rf","feedback":"الـ Rf في الـ period 7، وفي الـ period n بيتملي الـ $(n-1)d$ sublevel."}],"explanation":"الـ period 4 → 3d (1st)، الـ period 5 → 4d (2nd)، الـ period 6 → 5d (3rd)، الـ period 7 → 6d (4th)."}},"s6":{"q1":{"options":[{"id":"a","feedback":"الـ Sr هو $5s^2$، ومفيهوش ولا d electron. ده في الـ s-block، الـ group IIA."},{"id":"b","feedback":"صح: الـ $\\ce{_{39}Y}$ $(5s^2\\ 4d^1)$ عنده أول 4d electron."},{"id":"c","feedback":"الـ Zr عنده $4d^2$. فيه عنصر قبله على طول عنده 4d electron خلاص."},{"id":"d","feedback":"الـ Sc بيبدأ الـ first series، في الـ period 4. والـ second series في الـ period اللي تحتها."}],"explanation":"الـ yttrium، $\\ce{_{39}Y}$ $(5s^2\\ 4d^1)$، هو اللي بيبدأ الـ second transition series: ده أول عنصر في الـ period 5 عنده 4d electron."},"q2":{"options":[{"id":"a","feedback":"مظبوط: في ترتيب الملء الـ 3d بييجي بعد الـ 4s، فالـ 3d بيتملي في الـ period 4."},{"id":"b","feedback":"الـ period 1 فيه H و He وخلاص، ومفيهوش d sublevel أصلًا. والـ first series بتيجي بعد الـ calcium، في الـ period 4."},{"id":"c","feedback":"دي فكرة «نفس رقم الـ period». أول عنصر، الـ Sc، هو $4s^2\\ 3d^1$، يعني الـ d اللي بيتملي مش 4d."}],"explanation":"الـ first transition series بتملا الـ 3d، مش الـ 4d: في الـ period n بيتملي الـ (n−1)d sublevel، عشان الـ 3d بييجي بعد الـ 4s في ترتيب الملء. وأول عنصر فيها، الـ Sc، هو $4s^2\\ 3d^1$."}},"s7":{"exam":{"body":"**الـ first transition series**: العناصر اللي بيتملي فيها الـ sublevel **(3d) بالتتابع**. موجودة في **الـ fourth period بعد الـ calcium**؛ عشرة عناصر، من الـ scandium للـ zinc."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":3,"lesson_no":16,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-position","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"The transition elements and their series","duration_s":496.589,"start_s":203.9,"end_s":299.5,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.transition-series","kind":"short","chapter_id":"chem-s3-en.ch1","title":"The four transition series","duration_s":47.32,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":5,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition 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So why does the book call them economically important?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Scarce but valuable?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"pt":{"type":"PeriodicTable","props":{"caption":"The first transition series: Sc (21) to Zn (30)","highlight_symbols":["Sc","Ti","V","Cr","Mn","Fe","Co","Ni","Cu","Zn"]},"children":[]},"book":{"type":"Text","props":{"content":"This series contains ten elements: scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu) and zinc (Zn)."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["recall","pt","book","trap"]},"trap":{"type":"Callout","props":{"variant":"warning"},"children":[]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: the first transition series is in period 4, after calcium. The 3d sublevel fills."},"children":[]}}},"title":"Ten elements, Z = 21 to 30"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"z":21},"elements":{"t":{"type":"Text","props":{"content":"Slide along the series, one element at a time."},"children":[]},"sl":{"type":"Slider","props":{"max":30,"min":21,"step":1,"label":"Atomic number, Z","value":{"$bindState":"/z"}},"children":[]},"st":{"type":"Stat","props":{"tone":"brand","label":"Position in the series","value":{"args":{"z":{"$state":"/z"},"expr":"z - 20","digits":0},"$computed":"calc"}},"children":[]},"e21":{"type":"Text","props":{"content":"$\\ce{_{21}Sc}$: **scandium**, group IIIB. % wt in the earth's crust: 0.0026"},"visible":{"eq":21,"$state":"/z"},"children":[]},"e22":{"type":"Text","props":{"content":"$\\ce{_{22}Ti}$: **titanium**, group IVB. % wt in the earth's crust: 0.66"},"visible":{"eq":22,"$state":"/z"},"children":[]},"e23":{"type":"Text","props":{"content":"$\\ce{_{23}V}$: **vanadium**, group VB. % wt in the earth's crust: 0.02"},"visible":{"eq":23,"$state":"/z"},"children":[]},"e24":{"type":"Text","props":{"content":"$\\ce{_{24}Cr}$: **chromium**, group VIB. % wt in the earth's crust: 0.014"},"visible":{"eq":24,"$state":"/z"},"children":[]},"e25":{"type":"Text","props":{"content":"$\\ce{_{25}Mn}$: **manganese**, group VIIB. % wt in the earth's crust: 0.11"},"visible":{"eq":25,"$state":"/z"},"children":[]},"e26":{"type":"Text","props":{"content":"$\\ce{_{26}Fe}$: **iron**, group VIII. % wt in the earth's crust: 5"},"visible":{"eq":26,"$state":"/z"},"children":[]},"e27":{"type":"Text","props":{"content":"$\\ce{_{27}Co}$: **cobalt**, group VIII. % wt in the earth's crust: 0.003"},"visible":{"eq":27,"$state":"/z"},"children":[]},"e28":{"type":"Text","props":{"content":"$\\ce{_{28}Ni}$: **nickel**, group VIII. % wt in the earth's crust: 0.0089"},"visible":{"eq":28,"$state":"/z"},"children":[]},"e29":{"type":"Text","props":{"content":"$\\ce{_{29}Cu}$: **copper**, group IB. % wt in the earth's crust: 0.0068"},"visible":{"eq":29,"$state":"/z"},"children":[]},"e30":{"type":"Text","props":{"content":"$\\ce{_{30}Zn}$: **zinc**, group IIB. % wt in the earth's crust: 0.0078"},"visible":{"eq":30,"$state":"/z"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","st","e21","e22","e23","e24","e25","e26","e27","e28","e29","e30"]}}},"title":"Walk along the series"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"r":{"type":"Reveal","props":{"label":"Zoom in on the rare ones"},"children":["ch2"]},"t":{"type":"Text","props":{"content":"Iron towers over the rest. Most of the others are far below 1%."},"children":[]},"ch":{"type":"Chart","props":{"kind":"bar","unit":"%","series":[{"name":"% wt","points":[{"x":"Sc","y":0.0026},{"x":"Ti","y":0.66},{"x":"V","y":0.02},{"x":"Cr","y":0.014},{"x":"Mn","y":0.11},{"x":"Fe","y":5},{"x":"Co","y":0.003},{"x":"Ni","y":0.0089},{"x":"Cu","y":0.0068},{"x":"Zn","y":0.0078}]}],"caption":"The book's table: percent of each element in the earth's crust","x_label":"element","y_label":"% by weight in the earth's crust","highlight":["Fe"]},"children":[]},"ch2":{"type":"Chart","props":{"kind":"bar","unit":"%","series":[{"name":"% wt","points":[{"x":"Sc","y":0.0026},{"x":"V","y":0.02},{"x":"Cr","y":0.014},{"x":"Mn","y":0.11},{"x":"Co","y":0.003},{"x":"Ni","y":0.0089},{"x":"Cu","y":0.0068},{"x":"Zn","y":0.0078}]}],"caption":"Without Fe and Ti: Sc (0.0026%) and Co (0.003%) are the rarest","x_label":"element","y_label":"% by weight in the earth's crust","highlight":["Sc","Co"]},"children":[]},"book":{"type":"Text","props":{"content":"All of these elements form **nearly 7% of the weight of the earth's crust**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["ch","book","t","r"]}}},"title":"How much is in the earth's crust?"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"cmp":{"type":"Card","props":{"tone":"info","title":"Contrast case: scandium (preview of the uses lessons)"},"children":["cmpt"]},"book":{"type":"Text","props":{"content":"These elements form nearly 7% of the weight of the earth's crust, **but they have high economic importance**."},"children":[]},"cmpt":{"type":"Text","props":{"content":"Scandium is the rarest of the ten (0.0026%). Yet adding a little scandium to aluminum gives a light and very hard alloy."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","trap","cmp"]},"trap":{"type":"TrueFalse","props":{"answer":false,"statement":"A metal is important because there is a lot of it in the earth's crust."},"children":[]}}},"title":"Scarce, yet important"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"o":{"type":"Ordering","props":{"items":[{"id":"v","text":"V"},{"id":"cr","text":"Cr"},{"id":"mn","text":"Mn"},{"id":"fe","text":"Fe"},{"id":"co","text":"Co"},{"id":"ni","text":"Ni"}],"prompt":"Put these elements in order of increasing atomic number."},"children":[]},"q":{"type":"FillBlank","props":{"text":"The element of the first transition series with Z = 28 is ___ (symbol).","answers":[["Ni","nickel"]],"mistakes":[{"id":"m1","blank":0,"answer":"Co"},{"id":"m2","blank":0,"answer":"Cu"},{"id":"m3","blank":0,"answer":"Fe"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o","q"]}}},"title":"Order and symbols"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Manganese, Mn","correct":false},{"id":"b","text":"Titanium, Ti","correct":true},{"id":"c","text":"Copper, Cu","correct":false},{"id":"d","text":"Zinc, Zn","correct":false}],"question":"Using the table, which element is the second most abundant of the ten?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Cobalt is one of the rarest elements of the series in the crust, so it has little economic importance."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Sc",0.0026],["Ti",0.66],["V",0.02],["Cr",0.014],["Mn",0.11],["Fe",5],["Co",0.003],["Ni",0.0089],["Cu",0.0068],["Zn",0.0078]],"caption":"Percent of each element in the earth's crust (book, p.5)","headers":["Element","% wt"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tab","q","tf"]}}},"title":"Read the table"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Ten elements: Sc (21), Ti (22), V (23), Cr (24), Mn (25), Fe (26), Co (27), Ni (28), Cu (29), Zn (30).","Iron is the most abundant of them (about 5% of the crust).","They are scarce, yet they have high economic importance."]},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Sc",21,0.0026],["Ti",22,0.66],["V",23,0.02],["Cr",24,0.014],["Mn",25,0.11],["Fe",26,5],["Co",27,0.003],["Ni",28,0.0089],["Cu",29,0.0068],["Zn",30,0.0078]],"caption":"The first transition series: atomic number and % by weight in the earth's crust (book, p.5)","headers":["Element","Z","% wt"],"highlight":[{"col":2,"row":5}]},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tab","exam","self"]},"self":{"type":"Text","props":{"content":"Can you explain why scandium matters to industry, though it is the rarest of the ten?"},"children":[]}}},"title":"Summary"}],"title":"Elements of the first transition series","minutes":8,"book_ref":"Ch.1 '1-The First Transition Series' + table of the percent of each element in the earth's crust, p.5","subtitle":"Ten metals from Sc to Zn: scarce, yet important","objectives":["List the ten elements of the first transition series in order, with symbols and atomic numbers: Sc (21) to Zn (30).","Read the book's table of the percent of each element in the earth's crust.","Explain that these elements have high economic importance, though they form only nearly 7% of the weight of the earth's crust."],"concept_ids":["te.first-series-elements"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Copper is everywhere in wires, but that's daily use, not abundance in the crust."},{"id":"b","feedback":"Right: iron is about 5% by weight, far ahead of the rest."},{"id":"c","feedback":"Zinc is used a lot, but use is not the same as abundance."},{"id":"d","feedback":"Titanium is not bad, but one metal is far more abundant."}],"explanation":"Iron is the most abundant of the ten: about 5% by weight of the earth's crust, far ahead of the rest."}},"s2":{"trap":{"body":"Two pairs get swapped a lot: **Cr (24) comes before Mn (25)**, and **Co (27) comes before Ni (28)**. The order follows the atomic number.","title":"Watch the order"}},"s5":{"trap":{"explanation":"A metal's importance does not come from its amount: these ten elements form only nearly 7% of the earth's crust, yet they have high economic importance because of their properties and uses.","feedback_true":"That's the trap: scandium is the rarest of the ten, yet it makes a light, very hard alloy with aluminum.","feedback_false":"Correct: the amount of a metal does not decide its importance."}},"s6":{"o":{"items":[{"id":"v","feedback":"V (23) comes early in the series: two places after Sc (21)."},{"id":"cr","feedback":"Cr (24) comes before Mn (25): the order follows the atomic number."},{"id":"mn","feedback":"Mn (25) comes right after Cr (24)."},{"id":"fe","feedback":"Fe (26) is in the middle of the series, right after Mn (25)."},{"id":"co","feedback":"Co (27) comes before Ni (28): the order follows the atomic number."},{"id":"ni","feedback":"Ni (28) comes right after Co (27)."}],"explanation":"V (23), Cr (24), Mn (25), Fe (26), Co (27), Ni (28)."},"q":{"mistakes":[{"id":"m1","feedback":"Co is Z = 27, one place before the element with Z = 28."},{"id":"m2","feedback":"Cu is Z = 29, one place after the element with Z = 28."},{"id":"m3","feedback":"Fe is Z = 26, two places before the element with Z = 28."}],"explanation":"Fe (26), Co (27), Ni (28)."}},"s7":{"q":{"options":[{"id":"a","feedback":"Mn is 0.11%, which is not the second largest value in the table."},{"id":"b","feedback":"Correct: Ti is 0.66%, second only to Fe (5%)."},{"id":"c","feedback":"Copper is common in daily life, but its value in the table is small (0.0068%)."},{"id":"d","feedback":"Zinc is used a lot, but its value in the table is small (0.0078%)."}],"explanation":"In the table, Fe has the largest value (5%) and Ti the second largest (0.66%); Mn follows with 0.11%."},"tf":{"explanation":"Cobalt is rare in the crust (0.003%), but being scarce does not mean little economic importance: the elements of this series are scarce, yet they have high economic importance.","feedback_true":"That's the 'abundant = important' idea. Cobalt is rare (0.003%), but scarce metals can still have high economic importance: scandium, the rarest of the ten, is an example.","feedback_false":"Correct: cobalt is rare (0.003%), but scarce metals can still have high economic importance."}},"s8":{"exam":{"body":"They form **nearly 7% of the weight of the earth's crust**, but they have **high economic importance**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ copper موجود في كل حتة في الأسلاك، لكن ده استخدام يومي، مش نسبة وجوده في القشرة الأرضية."},{"id":"b","feedback":"صح: الـ iron حوالي 5% بالوزن، وسابق الباقيين بمسافة كبيرة."},{"id":"c","feedback":"الـ zinc بيتستخدم كتير، لكن كتر الاستخدام غير كتر الوجود."},{"id":"d","feedback":"الـ titanium مش وحش، لكن فيه metal تاني موجود بكمية أكبر بكتير."}],"explanation":"الـ iron هو أكتر واحد موجود من العشرة: حوالي 5% من وزن القشرة الأرضية، وسابق الباقيين بمسافة كبيرة."}},"s2":{"trap":{"body":"فيه زوجين بيتلخبطوا كتير: **الـ Cr (24) قبل الـ Mn (25)**، و**الـ Co (27) قبل الـ Ni (28)**. الترتيب ماشي على الـ atomic number.","title":"خلّي بالك من الترتيب"}},"s5":{"trap":{"explanation":"أهمية الـ metal مش جاية من كميته: العناصر العشرة دي يدوب حوالي 7% من وزن القشرة الأرضية، ومع كده ليها أهمية اقتصادية عالية بسبب خواصها واستخداماتها.","feedback_true":"ده الفخ: الـ scandium أندر واحد في العشرة، ومع كده بيدّي مع الـ aluminum سبيكة خفيفة وصلبة جدًا.","feedback_false":"مظبوط: كمية الـ metal مش هي اللي بتحدد أهميته."}},"s6":{"o":{"items":[{"id":"v","feedback":"الـ V (23) من أوائل السلسلة: بعد الـ Sc (21) بمكانين."},{"id":"cr","feedback":"الـ Cr (24) قبل الـ Mn (25): الترتيب ماشي بالـ atomic number."},{"id":"mn","feedback":"الـ Mn (25) بييجي بعد الـ Cr (24) على طول."},{"id":"fe","feedback":"الـ Fe (26) في نص السلسلة، بعد الـ Mn (25) على طول."},{"id":"co","feedback":"الـ Co (27) قبل الـ Ni (28): الترتيب ماشي بالـ atomic number."},{"id":"ni","feedback":"الـ Ni (28) بييجي بعد الـ Co (27) على طول."}],"explanation":"V (23)، Cr (24)، Mn (25)، Fe (26)، Co (27)، Ni (28)."},"q":{"mistakes":[{"id":"m1","feedback":"الـ Co الـ Z بتاعه 27، يعني قبل العنصر اللي الـ Z بتاعه 28 بمكان."},{"id":"m2","feedback":"الـ Cu الـ Z بتاعه 29، يعني بعد العنصر اللي الـ Z بتاعه 28 بمكان."},{"id":"m3","feedback":"الـ Fe الـ Z بتاعه 26، يعني قبل العنصر اللي الـ Z بتاعه 28 بمكانين."}],"explanation":"Fe (26)، Co (27)، Ni (28)."}},"s7":{"q":{"options":[{"id":"a","feedback":"الـ Mn نسبته 0.11%، ودي مش تاني أكبر قيمة في الجدول."},{"id":"b","feedback":"مظبوط: الـ Ti نسبته 0.66%، تاني واحد بعد الـ Fe (5%)."},{"id":"c","feedback":"الـ copper منتشر في حياتنا اليومية، لكن قيمته في الجدول صغيرة (0.0068%)."},{"id":"d","feedback":"الـ zinc بيتستخدم كتير، لكن قيمته في الجدول صغيرة (0.0078%)."}],"explanation":"في الجدول، الـ Fe أكبر قيمة (5%) والـ Ti تاني أكبر قيمة (0.66%)، وبعدهم الـ Mn بـ 0.11%."},"tf":{"explanation":"الـ cobalt نادر في القشرة الأرضية (0.003%)، لكن الندرة مش معناها أهمية اقتصادية قليلة: عناصر السلسلة دي نادرة، ومع كده ليها أهمية اقتصادية عالية.","feedback_true":"دي فكرة «الكتير = المهم». الـ cobalt نادر (0.003%)، لكن الـ metals النادرة ممكن برضه يبقى ليها أهمية اقتصادية عالية: والـ scandium، أندر واحد في العشرة، مثال على كده.","feedback_false":"مظبوط: الـ cobalt نادر (0.003%)، لكن الـ metals النادرة ممكن برضه يبقى ليها أهمية اقتصادية عالية."}},"s8":{"exam":{"body":"بيكوّنوا **تقريبًا 7% من وزن القشرة الأرضية**، لكن ليهم **أهمية اقتصادية عالية**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":4,"lesson_no":17,"lesson_count":17,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-position","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"The transition elements and their 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Blue light has about 450 nm. Which has the higher frequency?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"When the wavelength of light gets shorter, its frequency gets ___.","answers":[["higher","bigger","greater","larger","more","increases","higher frequency"]],"mistakes":[{"id":"m1","blank":0,"answer":"lower"},{"id":"m2","blank":0,"answer":"smaller"},{"id":"m3","blank":0,"answer":"less"},{"id":"m4","blank":0,"answer":"the same"},{"id":"m5","blank":0,"answer":"same"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","fb"]}}},"title":"Your turn"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Light travels as waves that carry energy, even through empty space.","**Wavelength**: the distance between two neighbouring crests.","**Frequency**: the number of waves that pass a point in one second (Hz).","For light, a shorter wavelength means a higher frequency."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Key words"}},"children":[]},"tbl":{"type":"DataTable","props":{"rows":[[400,7.5],[500,6],[600,5],[700,4.3]],"caption":"Same speed in empty space: shorter wavelength, higher frequency (values from the slider above).","headers":["Wavelength (nm)","Frequency (× 10¹⁴ Hz)"]},"children":[]},"next":{"type":"Text","props":{"muted":true,"content":"Next: light is only one member of a bigger family of waves."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tbl","ex","next","self"]},"self":{"type":"Text","props":{"content":"Can you explain why blue light has a higher frequency than red light?"},"children":[]}}},"title":"Summary"}],"title":"Light and waves","minutes":5,"book_ref":"Prerequisite (preparatory science); used for UV in Ch.1 economic importance, 2-Titanium (TiO2 sunscreen), p.5","subtitle":"Wavelength and frequency, ready for the electromagnetic spectrum","objectives":["State that light travels as waves that carry energy.","Define wavelength and frequency.","Explain that, for light, a shorter wavelength means a higher frequency."],"concept_ids":["phys.waves-light"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Nice guess, but the space between the Sun and Earth is empty. There is no air to flow, so hot air cannot carry the energy across it."},{"id":"b","feedback":"Yes. Light travels as waves that carry energy, even through empty space."},{"id":"c","feedback":"Sound needs a material, like air, to travel. Space is empty, so no sound crosses it."}],"explanation":"Light travels as waves that carry energy, even through empty space. The space between the Sun and Earth has no air, so neither hot air nor sound can carry the energy across it."}},"s4":{"q":{"options":[{"id":"a","feedback":"That's the 'bigger wave, bigger number' idea. At the same speed, longer waves mean fewer waves pass each second, so a lower frequency, not a higher one."},{"id":"b","feedback":"Right. Same speed, shorter waves, so more waves pass each second."},{"id":"c","feedback":"The speed is the same, but the frequency is not: when the wavelength changes at the same speed, the number of waves passing each second changes too."}],"explanation":"All light has the same speed in empty space, so a shorter wavelength means more waves pass each second. Blue light (about 450 nm) has the shorter wavelength, so it has the higher frequency."},"fb":{"mistakes":[{"id":"m1","feedback":"That's the reverse. At the same speed, shorter waves mean the number of waves passing each second goes up, not down."},{"id":"m2","feedback":"That's the reverse. At the same speed, shorter waves mean the number of waves passing each second goes up, not down."},{"id":"m3","feedback":"That's the reverse. At the same speed, shorter waves mean the number of waves passing each second goes up, not down."},{"id":"m4","feedback":"The speed stays the same, but the frequency changes: on the slider, the frequency number changes as the wavelength changes."},{"id":"m5","feedback":"The speed stays the same, but the frequency changes: on the slider, the frequency number changes as the wavelength changes."}],"explanation":"Same speed: shorter waves mean more waves pass each second, so a higher frequency."}},"s5":{"ex":{"body":"Key words: **waves**, **energy**, **wavelength**, **frequency**, **shorter wavelength → higher frequency**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تخمين حلو، لكن المسافة بين الشمس والأرض فاضية، مفيهاش هوا أصلًا عشان يتحرك، فالهوا السخن مش هو اللي بيوصّل الـ energy."},{"id":"b","feedback":"أيوه. الضوء بيتنقل على شكل waves شايلة energy، حتى في الفضا الفاضي."},{"id":"c","feedback":"الصوت محتاج مادة، زي الهوا، عشان يتنقل فيها. والفضا فاضي، فالصوت مش بيعدّيه."}],"explanation":"الضوء بيتنقل على شكل waves شايلة energy، حتى في الفضا الفاضي. والمسافة بين الشمس والأرض مفيهاش هوا، فلا الهوا السخن ولا الصوت يقدروا يوصّلوا الـ energy."}},"s4":{"q":{"options":[{"id":"a","feedback":"دي فكرة «wave أكبر يبقى رقم أكبر». بنفس السرعة، الـ waves الأطول بيعدّي منها عدد أقل كل ثانية، يعني frequency أقل مش أعلى."},{"id":"b","feedback":"صح. نفس السرعة و waves أقصر، يعني waves أكتر بتعدّي كل ثانية."},{"id":"c","feedback":"السرعة واحدة فعلًا، لكن الـ frequency لأ: لما الـ wavelength يتغير والسرعة ثابتة، عدد الـ waves اللي بتعدّي كل ثانية بيتغير هو كمان."}],"explanation":"كل الضوء ليه نفس السرعة في الفضا الفاضي، فالـ wavelength الأقصر معناه waves أكتر بتعدّي كل ثانية. والضوء الأزرق (حوالي 450 nm) الـ wavelength بتاعه أقصر، فالـ frequency بتاعته أعلى."},"fb":{"mistakes":[{"id":"m1","feedback":"الـ wavelength والـ frequency بيمشوا عكس بعض طالما السرعة ثابتة، والإجابة دي ماشية معاه في نفس الاتجاه."},{"id":"m2","feedback":"الـ wavelength والـ frequency بيمشوا عكس بعض طالما السرعة ثابتة، والإجابة دي ماشية معاه في نفس الاتجاه."},{"id":"m3","feedback":"الـ wavelength والـ frequency بيمشوا عكس بعض طالما السرعة ثابتة، والإجابة دي ماشية معاه في نفس الاتجاه."},{"id":"m4","feedback":"السرعة هي اللي ثابتة، إنما الـ frequency بتتغير: على المؤشر، رقم الـ frequency بيتغير لما الـ wavelength يتغير."},{"id":"m5","feedback":"السرعة هي اللي ثابتة، إنما الـ frequency بتتغير: على المؤشر، رقم الـ frequency بيتغير لما الـ wavelength يتغير."}],"explanation":"طالما السرعة واحدة: waves أقصر يعني عدد أكبر منها بيعدّي كل ثانية، يعني frequency أعلى."}},"s5":{"ex":{"body":"الكلمات المهمة: **waves**، **energy**، **wavelength**، **frequency**، **shorter wavelength → higher frequency**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":1,"is_basics":true,"lesson_no":1,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-phys.waves-light","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Light and waves: from zero","duration_s":242.18,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-phys.waves-light","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Light and waves","duration_s":45.19,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-phys.em-spectrum","kind":"lesson","version":2,"catalog_version":3,"ord":78,"primary_concept_id":"phys.em-spectrum","concepts":[{"concept_id":"phys.em-spectrum","role":"primary"}],"title":"Electromagnetic radiation (UV, X-rays, gamma)","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Heat (infrared) from the Sun","correct":false},{"id":"b","text":"Ultraviolet (UV) rays from the Sun","correct":true},{"id":"c","text":"Bright visible light","correct":false}],"question":"Predict: what burns the skin?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"On a cloudy beach day you don't feel hot. 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347.0,23.9 348.0,27.6 349.0,32.8 350.0,38.9 351.0,45.2 352.0,50.9 353.0,55.2 354.0,57.6 355.0,57.8 356.0,55.5 357.0,51.1 358.0,45.2 359.0,38.5 360.0,31.9 361.0,26.5 362.0,23.0 363.0,22.0 364.0,23.8\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><rect x=\"4\" y=\"70\" width=\"52\" height=\"30\" fill=\"#64748b\" fill-opacity=\"0.35\" stroke=\"#64748b\" stroke-width=\"1.5\"/><text x=\"30\" y=\"89\" text-anchor=\"middle\" font-size=\"10.5\" fill=\"#e2e8f0\">Radio</text><rect x=\"56\" y=\"70\" width=\"52\" height=\"30\" fill=\"#f97316\" fill-opacity=\"0.35\" stroke=\"#f97316\" stroke-width=\"1.5\"/><text x=\"82\" y=\"83\" text-anchor=\"middle\" font-size=\"10\" fill=\"#e2e8f0\">Micro-</text><text x=\"82\" y=\"95\" text-anchor=\"middle\" font-size=\"10\" fill=\"#e2e8f0\">waves</text><rect x=\"108\" y=\"70\" width=\"52\" height=\"30\" fill=\"#ef4444\" fill-opacity=\"0.35\" stroke=\"#ef4444\" stroke-width=\"1.5\"/><text x=\"134\" y=\"89\" text-anchor=\"middle\" font-size=\"10.5\" 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stroke=\"#fbbf24\" stroke-width=\"2\" stroke-linecap=\"round\"/><polygon points=\"352.0,122.0 343.9,125.9 343.9,118.1\" fill=\"#fbbf24\"/><text x=\"186\" y=\"144\" text-anchor=\"middle\" font-size=\"13\" fill=\"#fbbf24\">shorter wavelength, higher frequency</text><text x=\"186\" y=\"164\" text-anchor=\"middle\" font-size=\"13\" fill=\"#fbbf24\">more energy</text></svg>","caption":"The electromagnetic spectrum: radio, microwaves, infrared, visible, UV, X-rays, gamma rays","max_width":380},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Electromagnetic radiation","definition":"Waves that carry energy at the speed of light, even through empty space."},"children":[]},"t":{"type":"Text","props":{"content":"Light is not the only electromagnetic radiation: radio waves, X-rays and gamma rays are too. Our eyes see only the visible part. In empty space, all of them travel at the same speed. They differ in wavelength. Shorter wavelength means higher frequency and more energy."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","d","t"]}}},"title":"A family of waves"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"n":1},"elements":{"t":{"type":"Text","props":{"content":"Slide from radio waves to gamma rays. Read what each one does."},"children":[]},"c1":{"type":"Card","props":{"tone":"info","title":"Radio waves"},"visible":{"eq":1,"$state":"/n"},"children":["c1t"]},"c2":{"type":"Card","props":{"tone":"warning","title":"Microwaves"},"visible":{"eq":2,"$state":"/n"},"children":["c2t"]},"c3":{"type":"Card","props":{"tone":"danger","title":"Infrared"},"visible":{"eq":3,"$state":"/n"},"children":["c3t"]},"c4":{"type":"Card","props":{"tone":"warning","title":"Visible light"},"visible":{"eq":4,"$state":"/n"},"children":["c4t"]},"c5":{"type":"Card","props":{"tone":"brand","title":"Ultraviolet (UV)"},"visible":{"eq":5,"$state":"/n"},"children":["c5t"]},"c6":{"type":"Card","props":{"tone":"info","title":"X-rays"},"visible":{"eq":6,"$state":"/n"},"children":["c6t"]},"c7":{"type":"Card","props":{"tone":"success","title":"Gamma rays"},"visible":{"eq":7,"$state":"/n"},"children":["c7t"]},"gm":{"type":"Misconception","props":{},"visible":{"eq":7,"$state":"/n"},"children":[]},"sl":{"type":"Slider","props":{"max":7,"min":1,"step":1,"label":"Position in the spectrum (1 = radio, 7 = gamma)","value":{"$bindState":"/n"}},"children":[]},"st":{"type":"Stat","props":{"tone":"brand","unit":"of 7","label":"Energy rank (1 = lowest)","value":{"$state":"/n"}},"children":[]},"c1t":{"type":"Text","props":{"content":"Longest wavelength, lowest energy. They carry radio and TV signals."},"children":[]},"c2t":{"type":"Text","props":{"content":"Shorter waves than radio. Used in microwave ovens and mobile phone signals."},"children":[]},"c3t":{"type":"Text","props":{"content":"Less energy than visible light. We feel it as heat, from the Sun or a hot stove."},"children":[]},"c4t":{"type":"Text","props":{"content":"The only part our eyes can see, from red to violet."},"children":[]},"c5t":{"type":"Text","props":{"content":"More energy than visible light. It can burn and damage the skin. Sunscreens are made to block it."},"children":[]},"c6t":{"type":"Text","props":{"content":"More energy than UV. They pass through skin, but less through bone, so they give X-ray images."},"children":[]},"c7t":{"type":"Text","props":{"content":"The shortest wavelength: the highest energy and the highest penetrating power."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","st","c1","c2","c3","c4","c5","c6","c7","gm"]}}},"title":"Walk along the spectrum"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"ir":{"type":"Card","props":{"tone":"danger","title":"Infrared"},"children":["irt"]},"tb":{"type":"DataTable","props":{"rows":[["Infrared","No","Less"],["Visible light","Yes","—"],["Ultraviolet (UV)","No","More"]],"headers":["Ray","Can our eyes see it?","Energy compared with visible light"]},"children":[]},"uv":{"type":"Card","props":{"tone":"brand","title":"Ultraviolet (UV)"},"children":["uvt"]},"irt":{"type":"Text","props":{"content":"Invisible. **Less** energy than visible light. We feel it only as warmth."},"children":[]},"uvt":{"type":"Text","props":{"content":"Invisible. **More** energy than visible light. It can burn the skin."},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["ir","uv"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["m","cols","tb"]}}},"title":"Invisible is not weak"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"radio","text":"Radio waves"},{"id":"mw","text":"Microwaves"},{"id":"ir","text":"Infrared"},{"id":"uv","text":"Ultraviolet (UV)"},{"id":"x","text":"X-rays"},{"id":"g","text":"Gamma rays"}],"answer":{"less":["radio","mw","ir"],"more":["uv","x","g"]},"prompt":"Sort each ray: less or more energy than visible light?","categories":[{"id":"less","label":"Less energy than visible light"},{"id":"more","label":"More energy than visible light"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"more energy and a shorter wavelength","correct":true},{"id":"b","text":"less energy, because they pass through gently","correct":false},{"id":"c","text":"the same energy, because all these rays have the same speed","correct":false},{"id":"d","text":"a longer wavelength and more energy","correct":false}],"question":"A hospital image shows bones through the skin. Compared with UV, the rays used have:"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Gamma rays are particles, not waves."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q","tf"]}}},"title":"Sort and apply"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Electromagnetic radiation: radio, microwaves, infrared, visible, ultraviolet (UV), X-rays, gamma rays. Light is only one member.","From radio to gamma: the wavelength gets shorter and the energy gets higher.","UV has more energy than visible light, so it can damage the skin.","Gamma rays are electromagnetic waves with the highest energy and the highest penetrating power."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Key words"}},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"UV has a shorter wavelength than visible light, so it carries more energy and can damage the skin. Infrared has less energy than visible light: we feel it only as warmth."},"children":[]},"next":{"type":"Text","props":{"muted":true,"content":"Next: which compound of titanium protects the skin from UV?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","ex","next","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why UV burns the skin, although infrared feels warmer?"},"children":[]}}},"title":"Summary"}],"title":"Electromagnetic radiation (UV, X-rays, gamma)","minutes":5,"book_ref":"Prerequisite (preparatory science); used in Ch.1 economic importance: TiO2 and UV (2-Titanium, p.5), cobalt-60 gamma rays (p.6), ZnS X-ray screens (p.7)","subtitle":"The family of light, and why UV harms the skin","objectives":["Name the members of the electromagnetic spectrum in order: radio, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays.","State that energy increases from radio waves to gamma rays, as the wavelength gets shorter.","Explain why UV rays can damage the skin although we cannot see them."],"concept_ids":["phys.em-spectrum"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Heat is what you feel, and you didn't feel hot. Something you can't see or feel is doing the damage."},{"id":"b","feedback":"Yes. UV rays: invisible, but with more energy than visible light. Let's see why."},{"id":"c","feedback":"It was cloudy, so the light was not bright. The burn comes from rays your eyes can't see."}],"explanation":"Sunburn comes from ultraviolet (UV) rays from the Sun: they are invisible and carry more energy than visible light, and they still reach you on a cloudy day."}},"s3":{"gm":{"statement":"Gamma rays are tiny particles.","correction":"Like light, gamma rays are electromagnetic waves, with the shortest wavelength and the most energy."}},"s4":{"m":{"statement":"UV is invisible, so it must be weak.","correction":"Seeing depends on our eyes, not on energy. UV has a shorter wavelength than visible light, so it carries more energy, and that is why it damages the skin."}},"s5":{"c":{"items":[{"id":"radio","feedback":"Radio waves have the longest wavelength, and a long wavelength means low energy."},{"id":"mw","feedback":"Microwaves sit between radio waves and infrared, with a longer wavelength than visible light's."},{"id":"ir","feedback":"Infrared is invisible, but invisible doesn't mean strong: it sits before visible light, on the long-wavelength side."},{"id":"uv","feedback":"That's the 'invisible means weak' trap: UV's wavelength is shorter than visible light's."},{"id":"x","feedback":"X-rays come after UV in the spectrum, on the short-wavelength side."},{"id":"g","feedback":"Gamma rays sit at the far end of the spectrum, the end with the shortest wavelength."}],"explanation":"Radio, microwaves and infrared have longer wavelengths than visible light: less energy. UV, X-rays and gamma rays have shorter wavelengths: more energy."},"q":{"options":[{"id":"a","feedback":"Right. These are X-rays: shorter wavelength than UV, so more energy and more penetrating."},{"id":"b","feedback":"Passing through the body needs more energy, not less."},{"id":"c","feedback":"Same speed in empty space, yes, but energy depends on wavelength, and these rays do not have the same wavelength as UV."},{"id":"d","feedback":"Wavelength and energy go in opposite directions, so more energy cannot come with a longer wavelength."}],"explanation":"Rays that show bones through the skin are X-rays. They have a shorter wavelength than UV, so they carry more energy and pass through the body more easily."},"tf":{"explanation":"Gamma rays are electromagnetic waves, like light, at the shortest-wavelength end of the spectrum.","feedback_true":"That mixes gamma rays up with particles. Gamma rays sit on the same spectrum as light, and every member of that family is an electromagnetic wave.","feedback_false":"Right. Gamma rays are electromagnetic waves, in the same family as light."}},"s6":{"ex":{"body":"Key words: **UV**, **X-rays**, **gamma rays**, **more energy**, **high penetrating power**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الحرارة حاجة بتحس بيها، وإنت محستش بحَر. فيه حاجة مش شايفها ولا حاسس بيها هي اللي بتعمل الضرر."},{"id":"b","feedback":"أيوه. الـ UV rays: مش بتتشاف، لكن فيها energy أكتر من الـ visible light. يلا نشوف ليه."},{"id":"c","feedback":"الجو كان غيم، يعني الضوء مكانش ساطع. الحرق جاي من rays عينيك مش بتشوفها."}],"explanation":"حرق الشمس سببه الـ ultraviolet (UV) rays اللي جاية من الشمس: مش بتتشاف، وفيها energy أكتر من الـ visible light، وبتوصلك حتى في يوم غيم."}},"s3":{"gm":{"statement":"الـ gamma rays دي particles صغيرة.","correction":"الـ gamma rays دي electromagnetic waves زي الضوء، لكن عندها أقصر wavelength وأكبر energy."}},"s4":{"m":{"statement":"الـ UV مش بيتشاف، يبقى أكيد ضعيف.","correction":"إننا نشوف الأشعة ولا لأ ده بيعتمد على عينينا، مش على الـ energy. الـ UV الـ wavelength بتاعته أقصر من الـ visible light، فبيشيل energy أكتر، وعشان كده بيأذي الجلد."}},"s5":{"c":{"items":[{"id":"radio","feedback":"الـ radio waves عندها أطول wavelength، والـ wavelength والـ energy بيمشوا عكس بعض."},{"id":"mw","feedback":"الـ microwaves واقعة بين الـ radio waves والـ infrared، والـ wavelength بتاعتها أطول من بتاعة الـ visible light."},{"id":"ir","feedback":"الـ infrared مش بيتشاف، لكن إنه مش بيتشاف ده مش معناه إنه قوي: الـ wavelength بتاعته أطول من بتاعة الـ visible light."},{"id":"uv","feedback":"دي فخ «اللي مش بيتشاف يبقى ضعيف»: الـ wavelength بتاعة الـ UV أقصر من بتاعة الـ visible light."},{"id":"x","feedback":"الـ X-rays جاية بعد الـ UV في الـ spectrum، يعني الـ wavelength بتاعتها أقصر من الـ visible light."},{"id":"g","feedback":"الـ gamma rays واقعة في الطرف الأخير من الـ spectrum، الطرف اللي فيه أقصر wavelength."}],"explanation":"الـ radio والـ microwaves والـ infrared الـ wavelength بتاعتهم أطول من الـ visible light، يعني energy أقل. أما الـ UV والـ X-rays والـ gamma rays فالـ wavelength بتاعتهم أقصر، يعني energy أكتر."},"q":{"options":[{"id":"a","feedback":"صح. دي X-rays: الـ wavelength بتاعتها أقصر من الـ UV، يعني energy أكتر و penetrating power أعلى."},{"id":"b","feedback":"عشان الـ rays تعدّي من الجسم محتاجة energy أكتر، مش أقل."},{"id":"c","feedback":"نفس السرعة في الفضا الفاضي، أيوه. لكن الـ energy بتعتمد على الـ wavelength، والـ wavelength بتختلف من نوع أشعة للتاني."},{"id":"d","feedback":"الـ wavelength والـ energy بيمشوا عكس بعض، فمينفعش الاتنين يزيدوا مع بعض."}],"explanation":"الأشعة اللي بتورّي العضم من خلال الجلد هي الـ X-rays. الـ wavelength بتاعتها أقصر من الـ UV، فالـ energy بتاعتها أكتر وبتعدّي من الجسم أسهل."},"tf":{"explanation":"الـ gamma rays دي electromagnetic waves زي الضوء، في طرف الـ spectrum اللي فيه أقصر wavelength.","feedback_true":"كده إنت بتخلط بين الـ gamma rays والـ particles: الـ gamma rays موجودة على نفس الـ spectrum بتاع الضوء، يعني من نفس عيلة الـ waves.","feedback_false":"صح. الـ gamma rays دي electromagnetic waves، من نفس عيلة الضوء."}},"s6":{"ex":{"body":"الكلمات المهمة: **UV**، **X-rays**، **gamma rays**، **more energy**، **high penetrating power**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":2,"is_basics":true,"lesson_no":2,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-phys.em-spectrum","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Electromagnetic radiation (UV, X-rays, gamma): from zero","duration_s":251.77,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-phys.em-spectrum","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Electromagnetic radiation (UV, X-rays, gamma)","duration_s":46.78,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-te.uses-sc-ti","kind":"lesson","version":3,"catalog_version":3,"ord":80,"primary_concept_id":"te.uses-sc-ti","concepts":[{"concept_id":"te.uses-sc-ti","role":"primary"}],"title":"Economic importance of scandium and titanium","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It is the hardest metal","correct":false},{"id":"b","text":"It is inert, so the body does not reject it","correct":true},{"id":"c","text":"It is the cheapest metal","correct":false}],"question":"Predict: why is titanium used in dental implants?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"A dentist fixes a metal post into a jawbone, and it stays for years. Why titanium, and not just any hard metal?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Why titanium?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Most transition elements are found in small amounts in the earth's crust. But they have high economic importance."},"children":[]},"sc":{"type":"Text","props":{"content":"**Scandium** is found in very small amount spread on a large area in the earth's crust."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Sc","0.0026"],["Ti","0.66"],["V","0.02"],["Cr","0.014"],["Mn","0.11"],["Fe","5"],["Co","0.003"],["Ni","0.0089"],["Cu","0.0068"],["Zn","0.0078"]],"caption":"The percent of each transition element in the earth's crust (book table)","headers":["Element","% wt in the earth's crust"],"highlight":[{"col":1,"row":0},{"col":1,"row":1}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","tab","sc"]}}},"title":"Small amounts, big value"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"TrueFalse","props":{"answer":false,"statement":"MiG fighter jets are made of pure scandium."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"alloy","from":"al"},{"to":"mig","from":"alloy","label":"used in"}],"nodes":[{"id":"al","label":"Aluminum + a little scandium"},{"id":"alloy","label":"Light and very hard alloy"},{"id":"mig","label":"MiG fighter jets"}]},"children":[]},"lt":{"type":"Text","props":{"content":"Scandium is also added to **mercury vapour lamps**. They give high-quality light that looks like sunlight."},"children":[]},"rv":{"type":"Reveal","props":{"label":"Scandium's second use"},"children":["lt","lfd"]},"lfd":{"type":"FlowDiagram","props":{"edges":[{"to":"light","from":"lamp"},{"to":"tv","from":"light","label":"used in"}],"nodes":[{"id":"lamp","label":"Mercury vapour lamp + scandium"},{"id":"light","label":"High-quality light, like sunlight"},{"id":"tv","label":"TV photography at night"}]},"children":[]},"book":{"type":"Text","props":{"content":"Adding a **little amount of scandium to aluminum** gives a **light and very hard alloy**. An alloy is a metal mixed with other elements; you'll study alloys later. This alloy is used in MiG fighter jets."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","fd","m","rv"]}}},"title":"1- Scandium"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"A shuttle must be strong, light and heat-proof. Titanium covers aluminum's weak point: heat."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Steel","rigid","denser than titanium","—"],["Titanium","as rigid as steel","less dense than steel","maintains its durability"],["Aluminum","—","light","its hardness decreases"]],"caption":"Why titanium joins aluminum in aircraft","headers":["","Rigidity","Density","At high temperatures"],"highlight":[{"col":3,"row":1},{"col":3,"row":2}]},"children":[]},"book":{"type":"Text","props":{"content":"Titanium is as rigid as steel, but less dense than steel. Its alloys with aluminum are used in **aircraft and space shuttles**. Reason: it **maintains its durability at high temperatures, while the hardness of aluminum decreases**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","tab","t"]}}},"title":"2- Titanium in aircraft"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 340 260\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"40\" y=\"130\" width=\"160\" height=\"120\" rx=\"10\" fill=\"#d6b98c\" fill-opacity=\"0.25\" stroke=\"#d6b98c\" stroke-width=\"2\"/><path d=\"M40 130 Q120 112 200 130\" fill=\"none\" stroke=\"#f472b6\" stroke-width=\"4\"/><rect x=\"104\" y=\"120\" width=\"32\" height=\"110\" rx=\"6\" fill=\"#94a3b8\" fill-opacity=\"0.5\" stroke=\"#cbd5e1\" stroke-width=\"2\"/><line x1=\"98\" y1=\"132\" x2=\"142\" y2=\"138\" stroke=\"#cbd5e1\" stroke-width=\"2\"/><line x1=\"98\" y1=\"144\" x2=\"142\" y2=\"150\" stroke=\"#cbd5e1\" stroke-width=\"2\"/><line x1=\"98\" y1=\"156\" x2=\"142\" y2=\"162\" stroke=\"#cbd5e1\" stroke-width=\"2\"/><line x1=\"98\" y1=\"168\" x2=\"142\" y2=\"174\" stroke=\"#cbd5e1\" stroke-width=\"2\"/><line x1=\"98\" y1=\"180\" x2=\"142\" y2=\"186\" stroke=\"#cbd5e1\" stroke-width=\"2\"/><line x1=\"98\" y1=\"192\" x2=\"142\" y2=\"198\" stroke=\"#cbd5e1\" stroke-width=\"2\"/><line x1=\"98\" y1=\"204\" x2=\"142\" y2=\"210\" stroke=\"#cbd5e1\" stroke-width=\"2\"/><line x1=\"98\" y1=\"216\" x2=\"142\" y2=\"222\" stroke=\"#cbd5e1\" stroke-width=\"2\"/><rect x=\"110\" y=\"96\" width=\"20\" height=\"26\" fill=\"#cbd5e1\" fill-opacity=\"0.6\" stroke=\"#cbd5e1\" stroke-width=\"1.5\"/><path d=\"M86 98 Q84 40 100 30 Q120 22 140 30 Q156 40 154 98 Z\" fill=\"#f8fafc\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><line x1=\"156\" y1=\"60\" x2=\"215\" y2=\"60\" stroke=\"#94a3b8\" stroke-width=\"1\"/><text x=\"220\" y=\"65\" font-size=\"14\" fill=\"#e2e8f0\">crown</text><line x1=\"142\" y1=\"175\" x2=\"215\" y2=\"175\" stroke=\"#94a3b8\" stroke-width=\"1\"/><text x=\"220\" y=\"171\" font-size=\"14\" fill=\"#fbbf24\">titanium</text><text x=\"220\" y=\"188\" font-size=\"14\" fill=\"#fbbf24\">implant</text><line x1=\"190\" y1=\"235\" x2=\"215\" y2=\"235\" stroke=\"#94a3b8\" stroke-width=\"1\"/><text x=\"220\" y=\"240\" font-size=\"14\" fill=\"#e2e8f0\">jawbone</text></svg>","caption":"fig (1-2): a dental implant made of titanium","max_width":340},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Inert substance","definition":"A substance that does not react. The body does not reject titanium, and it causes no poisoning."},"children":[]},"m":{"type":"TrueFalse","props":{"answer":false,"statement":"Titanium is used in dental implants and artificial joints because it is hard."},"children":[]},"book":{"type":"Text","props":{"content":"So titanium is used in **dental implants** and **artificial joints**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","k","book","m"]}}},"title":"Titanium inside the body"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q1":{"type":"MCQ","props":{"options":[{"id":"a","text":"It is inert","correct":true},{"id":"b","text":"It is as rigid as steel","correct":false},{"id":"c","text":"It is less dense than steel","correct":false},{"id":"d","text":"It maintains its durability at high temperatures","correct":false}],"question":"A surgeon fixes a broken arm bone with a metal plate that stays inside for years. Which property makes titanium safe for this?"},"children":[]},"q2":{"type":"MCQ","props":{"options":[{"id":"a","text":"Titanium maintains its durability at high temperatures, while the hardness of aluminum decreases.","correct":true},{"id":"b","text":"Titanium is inert, so the body does not reject it.","correct":false},{"id":"c","text":"Titanium is denser than steel, so it is stronger.","correct":false},{"id":"d","text":"A little scandium is added to make the alloy light.","correct":false}],"question":"Give a reason: titanium-aluminum alloys are used in space shuttles."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q1","q2"]}}},"title":"Match the reason"},{"id":"s7","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{TiO2}","caption":"Titanium dioxide: a famous titanium compound"},"children":[]},"m":{"type":"TrueFalse","props":{"answer":false,"statement":"Sun protection cosmetics contain titanium metal."},"children":[]},"book":{"type":"Text","props":{"content":"Titanium dioxide ($\\ce{TiO2}$) is used in **sun protection cosmetics**, where minute **nanoparticles** prevent the effect of UV on the skin."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["recall","f","book","m"]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: UV rays carry more energy than visible light. They can damage the skin."},"children":[]}}},"title":"Titanium dioxide and UV"},{"id":"s8","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"lamp","text":"Added to mercury vapour lamps for TV photography at night"},{"id":"mig","text":"A little amount added to aluminum for MiG fighter jets"},{"id":"shuttle","text":"Alloys with aluminum for space shuttles"},{"id":"joint","text":"Artificial joints"},{"id":"sun","text":"Sun protection cosmetics"}],"answer":{"sc":["lamp","mig"],"ti":["shuttle","joint"],"tio2":["sun"]},"prompt":"Sort each use: scandium, titanium, or titanium dioxide?","categories":[{"id":"sc","label":"Scandium"},{"id":"ti","label":"Titanium"},{"id":"tio2","label":"Titanium dioxide"}]},"children":[]},"fb":{"type":"FillBlank","props":{"text":"Titanium is used in artificial joints because it is an ___ substance, so the body does not reject it.","answers":[["inert"]],"mistakes":[{"id":"m1","blank":0,"answer":"hard"},{"id":"m2","blank":0,"answer":"strong"},{"id":"m3","blank":0,"answer":"rigid"},{"id":"m4","blank":0,"answer":"light"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","fb"]}}},"title":"Who does what?"},{"id":"s9","kind":"recap","spec":{"root":"root","elements":{"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Scandium","a little added to aluminum gives a light and very hard alloy","MiG fighter jets"],["Scandium","added to mercury vapour lamps: high-quality light that looks like sunlight","TV photography at night"],["Titanium-aluminum alloys","titanium maintains its durability at high temperatures, while the hardness of aluminum decreases","aircraft and space shuttles"],["Titanium","inert: the body does not reject it; no poisoning","dental implants, artificial joints"],["Titanium dioxide","minute nanoparticles prevent the effect of UV on the skin","sun protection cosmetics"]],"caption":"Each use has a reason (book p.5)","headers":["Substance","Property / reason","Use"]},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the dentist: titanium is chosen because it is **inert**, not just because it is hard."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["hook","tab","ex","self"]},"self":{"type":"Text","props":{"content":"Can you explain why titanium, and not just any hard metal, is used in artificial joints?"},"children":[]}}},"title":"Summary"}],"title":"Economic importance of scandium and titanium","minutes":9,"book_ref":"Ch.1 economic importance: crust table, 1-Scandium, 2-Titanium, p.5 (fig 1-2)","subtitle":"Each use has a reason","objectives":["Describe the uses of scandium: a little added to aluminum (MiG fighter jets) and in mercury vapour lamps (TV photography at night).","Explain why titanium-aluminum alloys are used in aircraft and space shuttles.","Explain why titanium is used in dental implants and artificial joints (it is inert).","State that titanium dioxide (TiO2) nanoparticles in sun protection cosmetics prevent the effect of UV on the skin."],"concept_ids":["te.uses-sc-ti"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Hardness helps, but many metals are hard; hardness is not the book's reason for implants."},{"id":"b","feedback":"Right: titanium is an inert substance, so the body does not reject it and it causes no poisoning."},{"id":"c","feedback":"Price is not the book's reason; inside the body, what matters is that the metal does not react."}],"explanation":"Titanium is an inert substance: it does not react, so the body does not reject it and it causes no poisoning. That, not hardness or price, is the book's reason for using it in dental implants."}},"s3":{"m":{"explanation":"MiG fighter jets use an alloy: a little amount of scandium is added to aluminum, which gives a light and very hard alloy.","feedback_true":"No. Only a little amount of scandium is added to aluminum, and that gives a light and very hard alloy used in MiG fighter jets.","feedback_false":"Right. A little amount of scandium is added to aluminum, giving a light and very hard alloy for MiG fighter jets."}},"s5":{"m":{"explanation":"The book's reason is that titanium is inert: the body does not reject it and it causes no poisoning. Many metals are hard, but inside the body the metal must not react.","feedback_true":"That misses the book's reason. Inside the body a metal must not react: titanium is an inert substance, so the body does not reject it and it causes no poisoning. Durability at high temperatures is the reason for aircraft, not implants.","feedback_false":"Right. The book's reason is that titanium is inert: the body does not reject it, and it causes no poisoning."}},"s6":{"q1":{"options":[{"id":"a","feedback":"Right. It is inert: the body does not reject it, and it causes no poisoning."},{"id":"b","feedback":"Rigidity helps the plate hold the bone, but being safe inside the body needs another property."},{"id":"c","feedback":"Being light doesn't stop poisoning; inside the body, the metal must not react."},{"id":"d","feedback":"That's the aircraft reason. The body is not hot like a shuttle, so durability at high temperatures is not what makes it safe."}],"explanation":"A plate that stays inside the body must not react with it. Titanium is inert, so the body does not reject it and it causes no poisoning; rigidity, low density and durability at high temperatures are its reasons for other uses."},"q2":{"options":[{"id":"a","feedback":"Yes. That's the book's reason, word for word: heat is aluminum's weak point."},{"id":"b","feedback":"That's the implant reason, for the body. A shuttle faces heat, and the hardness of aluminum decreases at high temperatures."},{"id":"c","feedback":"Titanium is less dense than steel, not denser, and density is not the book's reason for shuttles."},{"id":"d","feedback":"That's scandium's use, for MiG fighter jets; the question asks for titanium's reason."}],"explanation":"A space shuttle faces high temperatures. Titanium maintains its durability at high temperatures, while the hardness of aluminum decreases, so titanium-aluminum alloys are used in space shuttles."}},"s7":{"m":{"explanation":"Sun protection cosmetics contain the compound titanium dioxide ($\\ce{TiO2}$) as minute nanoparticles that prevent the effect of UV on the skin, not titanium metal.","feedback_true":"No. They contain the compound titanium dioxide ($\\ce{TiO2}$), as minute nanoparticles. An implant is titanium metal; a sunscreen holds a titanium compound.","feedback_false":"Right. Sunscreen holds the compound $\\ce{TiO2}$ as nanoparticles, not titanium metal."}},"s8":{"c":{"items":[{"id":"lamp","feedback":"Scandium is added to mercury vapour lamps to give light that looks like sunlight (step 3)."},{"id":"mig","feedback":"Scandium is the one added in a little amount to aluminum for MiG fighter jets; titanium's alloys with aluminum are for aircraft and space shuttles."},{"id":"shuttle","feedback":"Titanium maintains its durability at high temperatures, so its alloys with aluminum are used in space shuttles (step 4)."},{"id":"joint","feedback":"Artificial joints use titanium metal, which is inert, not its compound."},{"id":"sun","feedback":"Sunscreen holds the compound titanium dioxide, as nanoparticles, not the metal."}],"explanation":"Scandium: MiG jets (a little in aluminum) and mercury vapour lamps. Titanium: aircraft and shuttles, implants and joints. $\\ce{TiO2}$: sunscreen."},"fb":{"mistakes":[{"id":"m1","feedback":"Hard is not the book's reason here: inside the body, the metal must not react."},{"id":"m2","feedback":"Strength is not the book's reason here: inside the body, the metal must not react."},{"id":"m3","feedback":"Rigidity matters for aircraft; for the body, the book names a substance that does not react."},{"id":"m4","feedback":"Low density is not the reason for joints; the book's word means 'does not react'."}],"explanation":"Inert: it does not react, so the body does not reject it and there is no poisoning."}},"s9":{"ex":{"body":"Implants: **inert**, **not rejected**, **no poisoning**. Aircraft: **maintains its durability at high temperatures, while the hardness of aluminum decreases**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الصلابة بتساعد، لكن metals كتير صلبة؛ والصلابة مش هي سبب الكتاب لاستخدامه في زراعة الأسنان."},{"id":"b","feedback":"صح: الـ titanium مادة inert، فالجسم مابيرفضوش ومابيعملش أي تسمم."},{"id":"c","feedback":"السعر مش هو السبب اللي في الكتاب؛ جوه الجسم المهم إن الـ metal مايتفاعلش."}],"explanation":"الـ titanium ده inert substance: مش بيتفاعل، فالجسم مش بيرفضه ومش بيعمل تسمم. وده سبب الكتاب لاستخدامه في الـ dental implants، مش الصلابة ولا السعر."}},"s3":{"m":{"explanation":"الـ MiG fighter jets بتستخدم alloy: كمية صغيرة من الـ scandium بتتضاف للـ aluminum، فتدّي alloy خفيف وصلب جدًا.","feedback_true":"لأ. اللي بيتضاف يدوب كمية صغيرة من الـ scandium للـ aluminum، وده بيدّي alloy خفيف وصلب جدًا بيتستخدم في طيارات الـ MiG الحربية.","feedback_false":"صح. بيتضاف كمية صغيرة من الـ scandium للـ aluminum، فيدّي alloy خفيف وصلب جدًا لطيارات الـ MiG الحربية."}},"s5":{"m":{"explanation":"سبب الكتاب إن الـ titanium ده inert: الجسم مش بيرفضه ومش بيعمل تسمم. معادن كتير صلبة، لكن جوه الجسم المهم إن الـ metal مايتفاعلش.","feedback_true":"ده مش سبب الكتاب. جوه الجسم الـ metal لازم مايتفاعلش: الـ titanium مادة inert، فالجسم مابيرفضوش ومابيعملش أي تسمم. أما المتانة في درجات الحرارة العالية فدي سبب الطيارات، مش الزراعة.","feedback_false":"صح. سبب الكتاب إن الـ titanium مادة inert: الجسم مابيرفضوش، ومابيعملش أي تسمم."}},"s6":{"q1":{"options":[{"id":"a","feedback":"صح. هو inert: الجسم مابيرفضوش، ومابيعملش أي تسمم."},{"id":"b","feedback":"إنه جامد ده بيساعد الشريحة تمسك العضمة، لكن «آمن جوه الجسم» محتاجة خاصية تانية."},{"id":"c","feedback":"إنه خفيف ده مابيمنعش التسمم؛ جوه الجسم الـ metal لازم مايتفاعلش."},{"id":"d","feedback":"ده سبب الطيارات. الجسم مش سخن زي مكوك الفضاء، فالمتانة في درجات الحرارة العالية مش هي اللي بتخليه آمن."}],"explanation":"الشريحة اللي بتفضل جوه الجسم لازم ماتتفاعلش معاه. الـ titanium ده inert، فالجسم مش بيرفضه ومش بيعمل تسمم؛ أما إنه rigid وخفيف وبيحافظ على الـ durability في درجات الحرارة العالية فدي أسباب لاستخدامات تانية."},"q2":{"options":[{"id":"a","feedback":"أيوه. ده سبب الكتاب بالحرف: الحرارة هي نقطة ضعف الـ aluminum."},{"id":"b","feedback":"ده سبب الزراعة جوه الجسم. مكوك الفضاء بيواجه حرارة، والـ aluminum صلابته بتقل في درجات الحرارة العالية."},{"id":"c","feedback":"الـ titanium كثافته أقل من الـ steel، مش أكبر، والكثافة مش هي سبب الكتاب لاستخدامه في الـ space shuttles."},{"id":"d","feedback":"ده استخدام الـ scandium، في طيارات الـ MiG الحربية؛ والسؤال عن سبب الـ titanium."}],"explanation":"الـ space shuttle بتواجه درجات حرارة عالية. الـ titanium بيحافظ على الـ durability بتاعته في درجات الحرارة العالية، في حين إن صلابة الـ aluminum بتقل، وعشان كده الـ titanium-aluminum alloys بتتستخدم في الـ space shuttles."}},"s7":{"m":{"explanation":"الـ sun protection cosmetics فيها الـ compound اللي اسمه titanium dioxide ($\\ce{TiO2}$) على شكل nanoparticles صغيرة جدًا بتمنع تأثير الـ UV على الجلد، مش الـ titanium metal.","feedback_true":"لأ. فيها الـ compound الـ titanium dioxide ($\\ce{TiO2}$) على شكل nanoparticles صغيرة جدًا. الـ implant هو الـ titanium كـ metal؛ إنما كريم الشمس فيه compound من الـ titanium.","feedback_false":"صح. كريم الشمس فيه الـ compound الـ $\\ce{TiO2}$ على شكل nanoparticles، مش الـ titanium كـ metal."}},"s8":{"c":{"items":[{"id":"lamp","feedback":"الـ scandium بيتضاف للـ mercury vapour lamps عشان يدّي ضوء شبه ضوء الشمس (الخطوة 3)."},{"id":"mig","feedback":"الـ scandium هو اللي بيتضاف منه كمية صغيرة للـ aluminum في طيارات الـ MiG؛ أما الـ alloys بتاعة الـ titanium مع الـ aluminum فللطيارات ومكوكات الفضاء."},{"id":"shuttle","feedback":"الـ titanium بيحافظ على متانته في درجات الحرارة العالية، فالـ alloys بتاعته مع الـ aluminum بتتستخدم في مكوكات الفضاء (الخطوة 4)."},{"id":"joint","feedback":"المفاصل الصناعية بتستخدم الـ titanium نفسه كـ metal، وهو inert، مش الـ compound بتاعه."},{"id":"sun","feedback":"كريم الحماية من الشمس فيه الـ compound الـ titanium dioxide على شكل nanoparticles، مش الـ metal."}],"explanation":"الـ scandium: طيارات الـ MiG (كمية صغيرة في الـ aluminum) والـ mercury vapour lamps. الـ titanium: الطيارات ومكوكات الفضاء، وزراعة الأسنان والمفاصل. الـ $\\ce{TiO2}$: كريمات الحماية من الشمس."},"fb":{"mistakes":[{"id":"m1","feedback":"كلمة hard مش هي سبب الكتاب هنا: جوه الجسم الـ metal لازم مايتفاعلش."},{"id":"m2","feedback":"القوة (strong) مش هي سبب الكتاب هنا: جوه الجسم الـ metal لازم مايتفاعلش."},{"id":"m3","feedback":"إنه rigid ده مهم في الطيارات؛ إنما للجسم، الكتاب بيذكر مادة مابتتفاعلش."},{"id":"m4","feedback":"إن كثافته قليلة (light) مش هو السبب في المفاصل؛ كلمة الكتاب معناها «مابيتفاعلش»."}],"explanation":"الـ inert يعني مابيتفاعلش، فالجسم مابيرفضوش ومفيش تسمم."}},"s9":{"ex":{"body":"في زراعة الأسنان والمفاصل: الـ titanium **inert**، و**الجسم مابيرفضوش**، و**مابيعملش تسمم**. في الطيارات: الـ titanium **بيحافظ على الـ durability بتاعته في درجات الحرارة العالية، في حين إن صلابة الـ aluminum بتقل**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":1,"lesson_no":14,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-uses","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Economic importance of the first transition series","duration_s":767.019,"start_s":28.1,"end_s":106.1,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.uses-sc-ti","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Economic importance of scandium and titanium","duration_s":47.93,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.valency-formulas","kind":"lesson","version":3,"catalog_version":3,"ord":82,"primary_concept_id":"chem.valency-formulas","concepts":[{"concept_id":"chem.valency-formulas","role":"primary"}],"title":"Valency and writing chemical formulas","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"From the valencies of chromium (3) and oxygen (2)","correct":true},{"id":"b","text":"They are random numbers to remember","correct":false},{"id":"c","text":"From the masses of the atoms","correct":false}],"question":"Predict: where do the 2 and the 3 come from?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Chapter 1 writes chromium (III) oxide as $Cr_2O_3$. Why 2 and 3, and not CrO?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Why 2 and 3?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"g":{"type":"Text","props":{"muted":true,"content":"An atomic group, like $SO_4$, acts as one unit with its own valency."},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Valency","definition":"The combining power of an element: the number of electrons its atom gains, loses or shares in a chemical reaction."},"children":[]},"t":{"type":"Text","props":{"content":"Some elements have more than one valency. The Roman numeral in the name tells you which: iron (III) has valency 3."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["1","H, Na, K, Cl","$OH$, $NO_3$, $NH_4$"],["2","O, Mg, Ca, Zn","$SO_4$, $CO_3$"],["3","Al","$PO_4$"]],"caption":"Common valencies","headers":["Valency","Elements","Atomic groups"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","tab","t","g"]}}},"title":"Valency"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"h":{"type":"Heading","props":{"text":"Worked: aluminum oxide","level":3},"children":[]},"t":{"type":"Text","props":{"content":"Mn = 2 (from the name), $SO_4$ = 2. Swapping gives $Mn_2(SO_4)_2$. Now finish the last step."},"children":[]},"w":{"type":"BulletList","props":{"items":["Write the symbols: Al and O.","Write the valencies: Al = 3, O = 2.","Swap them: each valency becomes the other element's number of atoms → $Al_2O_3$.","Can 2 and 3 be divided by the same number? No, so $Al_2O_3$ is final."],"ordered":true},"children":[]},"fb":{"type":"FillBlank","props":{"text":"Simplified, manganese (II) sulphate is ___.","answers":[["mnso4"]],"mistakes":[{"id":"m1","blank":0,"answer":"mn2(so4)2"},{"id":"m2","blank":0,"answer":"mn2so4"},{"id":"m3","blank":0,"answer":"mnso42"}]},"children":[]},"h2":{"type":"Heading","props":{"text":"Your turn: manganese (II) sulphate","level":3},"children":[]},"hint":{"type":"HintLadder","props":{},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["h","w","h2","t","fb","hint"]}}},"title":"Worked, then your turn"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$Al_2(SO_4)_3$","correct":true},{"id":"b","text":"$Al_2SO_{43}$","correct":false},{"id":"c","text":"$Al_3(SO_4)_2$","correct":false},{"id":"d","text":"$AlSO_4$","correct":false}],"question":"Which is the formula of aluminum sulphate? (Al = 3, $SO_4$ = 2)"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"Iron (III) chloride: ___ . Zinc oxide: ___ .","answers":[["fecl3"],["zno"]],"mistakes":[{"id":"m1","blank":0,"answer":"fe3cl"},{"id":"m2","blank":0,"answer":"fecl"},{"id":"m3","blank":0,"answer":"fecl2"},{"id":"m4","blank":1,"answer":"zn2o2"},{"id":"m5","blank":1,"answer":"zno2"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fb","q"]}}},"title":"On your own"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Valency is the combining power of an element; the Roman numeral in a name gives it, e.g. chromium (III).","Write symbols → write valencies → swap → simplify.","An atomic group taken more than once goes in brackets: $Al_2(SO_4)_3$."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Key words"}},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"va","from":"sy"},{"to":"sw","from":"va"},{"to":"si","from":"sw"}],"nodes":[{"id":"sy","label":"Symbols: Cr and O"},{"id":"va","label":"Valencies: Cr = 3, O = 2"},{"id":"sw","label":"Swap: 2 Cr, 3 O"},{"id":"si","label":"Simplify: 2 and 3 cannot be divided by the same number"}],"layout":"horizontal","caption":"The four steps on the hook's compound, chromium (III) oxide"},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the hook: Cr (3) and O (2) swap to give $Cr_2O_3$. Nothing to simplify."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","fd","hook","ex","self"]},"self":{"type":"Text","props":{"content":"Can you explain why zinc oxide is ZnO and not $Zn_2O_2$?"},"children":[]}}},"title":"Summary"}],"title":"Valency and writing chemical formulas","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used for compound formulas in Ch.1 economic importance p.5-7 (e.g. $TiO_2$, $V_2O_5$, $Cr_2O_3$, $MnSO_4$, $CuSO_4$)","subtitle":"From a name to a formula, ready for Chapter 1's compounds","objectives":["Define valency and read it from a name with a Roman numeral, e.g. chromium (III).","Write a formula by swapping the valencies, then simplifying.","Use brackets for an atomic group taken more than once, e.g. $Al_2(SO_4)_3$."],"concept_ids":["chem.valency-formulas"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Yes. The valencies decide how many atoms combine. Let's see how."},{"id":"b","feedback":"They are not random: the numbers follow a rule, so you do not need to memorise them."},{"id":"c","feedback":"Masses do not decide the formula; the numbers of atoms come from each element's combining power."}],"explanation":"The 2 and the 3 come from the valencies: chromium (III) has valency 3 and oxygen has valency 2. Swapping them gives 2 Cr and 3 O, so $Cr_2O_3$."}},"s3":{"fb":{"mistakes":[{"id":"m1","feedback":"Good swap, but one step is missing: both numbers can be divided by 2."},{"id":"m2","feedback":"You simplified only one side; both numbers must be divided by the same number."},{"id":"m3","feedback":"The 2 outside the bracket belongs to the whole group, so it is divided too when you simplify."}],"explanation":"2 and 2 both divide by 2: one Mn and one $SO_4$, so $MnSO_4$."},"hint":{"hints":["Divide both numbers by 2.","When the group is taken once, you don't need brackets."]}},"s4":{"q":{"options":[{"id":"a","feedback":"Right. Three $SO_4$ groups, so the group goes in brackets."},{"id":"b","feedback":"The 3 must apply to the whole $SO_4$ group, and a group taken more than once goes in brackets."},{"id":"c","feedback":"The valencies stayed on their own atoms. In the swap, each valency goes to the other part."},{"id":"d","feedback":"This skips the swap. Al has valency 3 and $SO_4$ has 2: they do not simply cancel out."}],"explanation":"Al = 3 and $SO_4$ = 2. Swapping gives 2 Al and 3 $SO_4$ groups; 2 and 3 cannot be divided by the same number, and a group taken more than once goes in brackets: $Al_2(SO_4)_3$."},"fb":{"mistakes":[{"id":"m1","feedback":"The valencies went to the wrong atoms: each valency becomes the other element's number of atoms."},{"id":"m2","feedback":"This uses valency 1 for iron, but the Roman numeral (III) in the name gives iron valency 3."},{"id":"m3","feedback":"That is iron (II) chloride; the name says iron (III)."},{"id":"m4","feedback":"Good swap, but the last step is missing: both numbers can be divided by 2."},{"id":"m5","feedback":"Zinc and oxygen have the same valency, 2, so the swap gives 2 and 2, which simplify to 1 and 1."}],"explanation":"Fe (3) and Cl (1): $FeCl_3$. Zn (2) and O (2): $Zn_2O_2$ simplifies to $ZnO$."}},"s5":{"ex":{"body":"Key words: **valency**, **atomic group**, **swap**, **simplify**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"أيوه. الـ valencies هي اللي بتحدد كام ذرة بيتحدوا. يلا نشوف إزاي."},{"id":"b","feedback":"مش أرقام عشوائية: الأرقام دي ماشية على قاعدة، فمش محتاج تحفظها."},{"id":"c","feedback":"الكتل مش هي اللي بتحدد الـ formula؛ عدد الذرات جاي من الـ combining power بتاعة كل عنصر."}],"explanation":"الـ 2 والـ 3 جايين من الـ valencies: الـ chromium (III) الـ valency بتاعته 3 والـ oxygen الـ valency بتاعته 2. لما تبدّلهم يبقى 2 Cr و 3 O، يعني $Cr_2O_3$."}},"s3":{"fb":{"mistakes":[{"id":"m1","feedback":"تبديل حلو، لكن ناقصة خطوة: الرقمين ينفع يتقسموا على 2."},{"id":"m2","feedback":"إنت اختصرت ناحية واحدة؛ الرقمين لازم يتقسموا على نفس الرقم."},{"id":"m3","feedback":"رقم 2 اللي برا القوس تبع الـ group كلها، فهو كمان بيتقسم لما تختصر."}],"explanation":"2 و 2 الاتنين بيتقسموا على 2: يعني Mn واحد و $SO_4$ واحدة، يبقى $MnSO_4$."},"hint":{"hints":["اقسم الرقمين على 2.","لما الـ group تتاخد مرة واحدة، مش محتاج أقواس."]}},"s4":{"q":{"options":[{"id":"a","feedback":"صح. تلات groups من $SO_4$، عشان كده الـ group بتتحط بين أقواس."},{"id":"b","feedback":"رقم 3 لازم يتطبق على الـ group كلها، $SO_4$، والـ group اللي بتتاخد أكتر من مرة بتتحط بين أقواس."},{"id":"c","feedback":"الـ valencies فضلت على ذراتها. في التبديل، كل valency بتروح للجزء التاني."},{"id":"d","feedback":"كده إنت نطّيت التبديل. الـ Al الـ valency بتاعته 3 والـ $SO_4$ بتاعتها 2: مينفعش يلغوا بعض كده وخلاص."}],"explanation":"Al = 3 و $SO_4$ = 2. التبديل بيدّي 2 Al و 3 groups من $SO_4$؛ والـ 2 والـ 3 مينفعش يتقسموا على نفس الرقم، والـ group اللي بتتاخد أكتر من مرة بتتحط بين أقواس: $Al_2(SO_4)_3$."},"fb":{"mistakes":[{"id":"m1","feedback":"الـ valencies راحت للذرات الغلط: كل valency بتبقى عدد ذرات العنصر التاني."},{"id":"m2","feedback":"كده إنت اعتبرت الـ valency بتاعة الـ iron واحد، لكن الرقم الروماني (III) في الاسم بيقول إنها 3."},{"id":"m3","feedback":"ده iron (II) chloride؛ والاسم بيقول iron (III)."},{"id":"m4","feedback":"تبديل حلو، لكن ناقصة آخر خطوة: الرقمين ينفع يتقسموا على 2."},{"id":"m5","feedback":"الـ zinc والـ oxygen ليهم نفس الـ valency، 2، فالتبديل بيدّي 2 و 2، وبيتختصروا لـ 1 و 1."}],"explanation":"Fe (3) و Cl (1): $FeCl_3$. و Zn (2) و O (2): $Zn_2O_2$ بتتختصر لـ $ZnO$."}},"s5":{"ex":{"body":"الكلمات اللي هتقابلك في الامتحان: **valency**، **atomic group**، **swap** (بدّل)، **simplify** (اختصر)."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":3,"is_basics":true,"lesson_no":3,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-alloys","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Alloys and their types","duration_s":599.729,"start_s":434.3,"end_s":471.4,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.valency-formulas","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Valency and writing chemical formulas","duration_s":54.39,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.equation-balancing","kind":"lesson","version":2,"catalog_version":3,"ord":84,"primary_concept_id":"chem.equation-balancing","concepts":[{"concept_id":"chem.equation-balancing","role":"primary"}],"title":"Writing and balancing chemical equations","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{N2 + H2 -> NH3}"},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Yes: N and H appear on both sides","correct":false},{"id":"b","text":"No: the atom counts differ","correct":true},{"id":"c","text":"We can't tell without the conditions","correct":false}],"question":"Predict: count the atoms. Is this equation balanced?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"In a reaction, no atom is created or destroyed. Nitrogen and hydrogen react to give ammonia."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","f","q"]}}},"title":"Do the atoms add up?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Text","props":{"muted":true,"content":"Conditions, like a catalyst or temperature, go over the arrow: $\\ce{->[\\Delta]}$."},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Coefficient","definition":"The number written before a formula in an equation. It multiplies the whole formula."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["2 (coefficient)","two molecules"],["2 (subscript)","two Cl atoms in each molecule"],["total","2 × 2 = 4 Cl atoms"]],"headers":["In $2Cl_2$","Meaning"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","tab","m","c"]}}},"title":"Coefficients, not subscripts"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{H2 + O2 -> H2O}","caption":"Not balanced yet"},"children":[]},"t":{"type":"Text","props":{"content":"Fixing one atom can unbalance another. So always recount at the end."},"children":[]},"w":{"type":"BulletList","props":{"items":["Count: H 2 and 2; O 2 on the left, 1 on the right. O is not balanced.","Put 2 before $H_2O$: O is now 2 and 2. But H is now 2 on the left and 4 on the right.","Put 2 before $H_2$: H is 4 and 4.","Check every atom: H 4 = 4, O 2 = 2. Balanced: $\\ce{2H2 + O2 -> 2H2O}$."],"ordered":true},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","w","t"]}}},"title":"Worked: water"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"a":1,"b":1,"c":1},"elements":{"a":{"type":"Slider","props":{"max":4,"min":1,"step":1,"label":"Coefficient of $\\ce{N2}$","value":{"$bindState":"/a"}},"children":[]},"b":{"type":"Slider","props":{"max":6,"min":1,"step":1,"label":"Coefficient of $\\ce{H2}$","value":{"$bindState":"/b"}},"children":[]},"c":{"type":"Slider","props":{"max":4,"min":1,"step":1,"label":"Coefficient of $\\ce{NH3}$","value":{"$bindState":"/c"}},"children":[]},"t":{"type":"Text","props":{"content":"Set the coefficients for $\\ce{N2 + H2 -> NH3}$. Make both sides match."},"children":[]},"hl":{"type":"Stat","props":{"tone":"warning","label":"H left","value":{"args":{"b":{"$state":"/b"},"expr":"2 * b","digits":0},"$computed":"calc"}},"children":[]},"hr":{"type":"Stat","props":{"tone":"warning","label":"H right","value":{"args":{"c":{"$state":"/c"},"expr":"3 * c","digits":0},"$computed":"calc"}},"children":[]},"nl":{"type":"Stat","props":{"tone":"info","label":"N left","value":{"args":{"a":{"$state":"/a"},"expr":"2 * a","digits":0},"$computed":"calc"}},"children":[]},"nr":{"type":"Stat","props":{"tone":"info","label":"N right","value":{"args":{"c":{"$state":"/c"},"expr":"c","digits":0},"$computed":"calc"}},"children":[]},"ok":{"type":"Callout","props":{"variant":"tip"},"visible":[{"eq":1,"$state":"/a"},{"eq":3,"$state":"/b"},{"eq":2,"$state":"/c"}],"children":[]},"row":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["nl","nr","hl","hr"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","a","b","c","row","ok"]}}},"title":"Balance it yourself"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"e":{"type":"EquationBuilder","props":{"prompt":"Balance the equation.","answers":[4,3,2],"template":"\\ce{{?}Al + {?}O2 -> {?}Al2O3}"},"children":[]},"h":{"type":"HintLadder","props":{},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The subscript was changed, so the product is no longer magnesium oxide","correct":true},{"id":"b","text":"Nothing: the atoms are now equal on both sides","correct":false},{"id":"c","text":"The arrow should point the other way","correct":false},{"id":"d","text":"A coefficient was put before $O_2$","correct":false}],"question":"To balance $\\ce{Mg + O2 -> MgO}$, a student writes $\\ce{Mg + O2 -> MgO2}$. What is wrong?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["e","h","q"]}}},"title":"New equations"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Reactants → products; conditions are written over the arrow.","Balance by changing coefficients only, never subscripts.","Check: each kind of atom has the same count on both sides."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Key words"}},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_t"]},"hook":{"type":"Text","props":{"content":"Back to the hook: $\\ce{N2 + 3H2 -> 2NH3}$ has 2 N and 6 H on each side. No atom is lost."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","hook","ex","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why changing $H_2O$ to $H_2O_2$ is not a way to balance an equation?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"A subscript is part of the formula: changing $H_2O$ to $H_2O_2$ turns water into a different substance. Only coefficients may change: $\\ce{2H2 + O2 -> 2H2O}$."},"children":[]}}},"title":"Summary"}],"title":"Writing and balancing chemical equations","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used for every equation in Ch.1 (e.g. the Haber-Bosch method p.6, the reactions of iron)","subtitle":"Count the atoms on both sides","objectives":["Name the parts of an equation: reactants, products, coefficients, subscripts, conditions over the arrow.","Balance an equation by changing coefficients only, never subscripts.","Check a balanced equation by counting each kind of atom on both sides."],"concept_ids":["chem.equation-balancing"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Having the same elements on both sides is not enough: the atom counts must match too, and here N is 2 on the left and 1 on the right, H is 2 and 3."},{"id":"b","feedback":"Right. N: 2 on the left, 1 on the right. Atoms can't vanish, so coefficients are needed."},{"id":"c","feedback":"Conditions go over the arrow; they don't change atom counts, and the atom counts alone show whether the equation is balanced."}],"explanation":"The equation is not balanced: the left side has 2 N atoms and 2 H atoms, while the right side has 1 N atom and 3 H atoms. Atoms are not created or destroyed in a reaction, so coefficients are needed to make the counts equal."}},"s2":{"m":{"statement":"You can balance an equation by changing a subscript, for example $H_2O$ → $H_2O_2$.","correction":"Never change a subscript to balance: $H_2O$ → $H_2O_2$ changes water into a different substance. Change coefficients only."}},"s4":{"ok":{"body":"Balanced! N 2 = 2, H 6 = 6 with the lowest whole numbers.","title":"Balanced"}},"s5":{"e":{"explanation":"Al 4 = 4 and O 6 = 6: $\\ce{4Al + 3O2 -> 2Al2O3}$."},"h":{"hints":["Start with O: 2 on the left, 3 on the right. Which number do 2 and 3 both go into?","Make O equal 6 on both sides. Then count Al again."]},"q":{"options":[{"id":"a","feedback":"Right. Only coefficients may change: $\\ce{2Mg + O2 -> 2MgO}$."},{"id":"b","feedback":"Equal atom counts are not enough: $MgO_2$ is a different substance from MgO, because a subscript was changed."},{"id":"c","feedback":"The arrow's direction is not the problem; the error is inside the formula of the product."},{"id":"d","feedback":"No coefficient was added here; what changed is a number inside the product's formula."}],"explanation":"Changing the subscript turned the product into $MgO_2$, which is a different substance from magnesium oxide. Only coefficients may change when balancing: $\\ce{2Mg + O2 -> 2MgO}$."}},"s6":{"ex":{"body":"Key words: **balanced equation**, **coefficient**, **conditions over the arrow**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"إن نفس العناصر تبقى موجودة في الناحيتين مش كفاية: لازم عدد الذرات كمان يبقى متساوي، وهنا الـ N: 2 على الشمال و1 على اليمين، والـ H: 2 و3."},{"id":"b","feedback":"صح. الـ N: 2 على الشمال و1 على اليمين. والذرات مش بتختفي، يبقى محتاجين نحط أرقام قدام المواد."},{"id":"c","feedback":"الـ conditions بتتكتب فوق السهم، ومش بتغيّر عدد الذرات، وعدد الذرات لوحده هو اللي بيبيّن الـ equation دي balanced ولا لأ."}],"explanation":"الـ equation دي مش balanced: على الشمال فيه 2 ذرة N و 2 ذرة H، وعلى اليمين ذرة N واحدة و 3 ذرات H. والذرات مش بتتخلق ولا بتختفي في الـ reaction، عشان كده محتاجين coefficients تخلّي الأعداد متساوية."}},"s2":{"m":{"statement":"ممكن تظبط الـ equation وتخليها balanced لو غيّرت الـ subscript، زي إن $H_2O$ تبقى $H_2O_2$.","correction":"عمرك ما تغيّر subscript عشان تعمل balancing: لو $H_2O$ بقت $H_2O_2$ يبقى الماية اتحوّلت لمادة تانية خالص. اللي بيتغيّر هو الـ coefficients لوحدها."}},"s4":{"ok":{"body":"كده balanced! الـ N: 2 = 2، والـ H: 6 = 6، وبأصغر أرقام صحيحة.","title":"كده balanced"}},"s5":{"e":{"explanation":"كده الـ Al: 4 = 4، والـ O: 6 = 6: $\\ce{4Al + 3O2 -> 2Al2O3}$."},"h":{"hints":["ابدأ بالـ O: 2 على الشمال و3 على اليمين. أنهي رقم يقبل القسمة على 2 وعلى 3 مع بعض؟","خلّي الـ O يبقى 6 في الناحيتين. وبعدين عدّ الـ Al تاني."]},"q":{"options":[{"id":"a","feedback":"صح. الـ coefficients لوحدها هي اللي مسموح تتغير: $\\ce{2Mg + O2 -> 2MgO}$."},{"id":"b","feedback":"تساوي عدد الذرات مش كفاية: الـ $MgO_2$ مادة تانية غير الـ MgO، عشان الـ subscript اتغيّر."},{"id":"c","feedback":"اتجاه السهم مش هو المشكلة؛ الغلطة جوه الـ formula بتاعة الـ product."},{"id":"d","feedback":"محدش زوّد coefficient هنا؛ اللي اتغيّر رقم جوه الـ formula بتاعة الـ product نفسها."}],"explanation":"تغيير الـ subscript خلّى الـ product يبقى $MgO_2$، ودي مادة تانية غير الـ magnesium oxide. في الـ balancing الـ coefficients لوحدها هي اللي مسموح تتغير: $\\ce{2Mg + O2 -> 2MgO}$."}},"s6":{"ex":{"body":"الكلمات المهمة: **balanced equation**، **coefficient**، **conditions over the arrow**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":4,"is_basics":true,"lesson_no":4,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":459.5,"end_s":516.5,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.equation-balancing","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Writing and balancing chemical equations","duration_s":52.42,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.catalyst","kind":"lesson","version":3,"catalog_version":3,"ord":86,"primary_concept_id":"chem.catalyst","concepts":[{"concept_id":"chem.catalyst","role":"primary"}],"title":"Catalyst","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It is still there at the end, with the same mass","correct":true},{"id":"b","text":"It turns into the oxygen gas","correct":false},{"id":"c","text":"It is used up, little by little","correct":false}],"question":"Predict: what happens to the manganese dioxide?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Add a pinch of black manganese dioxide to hydrogen peroxide, and oxygen bubbles out fast. Is the black powder used up?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"The fizzing powder"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{2H2O2 ->[MnO2] 2H2O + O2}","caption":"Manganese dioxide is written over the arrow"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Catalyst","definition":"A substance that speeds up a chemical reaction without being used up or changed."},"children":[]},"t":{"type":"Text","props":{"content":"The catalyst is written **over the arrow**. It is not a reactant, and it is not a product."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t"]}}},"title":"What a catalyst is"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"add","from":"w1"},{"to":"rec","from":"add"},{"to":"same","from":"rec"}],"nodes":[{"id":"w1","label":"Weigh the $\\ce{MnO2}$"},{"id":"add","label":"Add it to $\\ce{H2O2}$: oxygen bubbles fast"},{"id":"rec","label":"Filter, dry and weigh it again"},{"id":"same","label":"Same mass as at the start"}],"layout":"vertical","caption":"The catalyst is recovered unchanged"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fd","m"]}}},"title":"Same mass at the end"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It speeds up the reaction and is recovered unchanged","correct":true},{"id":"b","text":"It is used up to make the oxygen","correct":false},{"id":"c","text":"It turns into potassium chloride","correct":false}],"question":"Oxygen is also made from potassium chlorate: $\\ce{2KClO3 ->[MnO2][\\Delta] 2KCl + 3O2}$. What happens to the $\\ce{MnO2}$?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"In a chemical equation, the catalyst is written ___ the arrow.","answers":[["over","above","on"]],"mistakes":[{"id":"m1","blank":0,"answer":"before"},{"id":"m2","blank":0,"answer":"after"}]},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Adding a catalyst makes a reaction produce more product."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf","fb"]}}},"title":"Try a new reaction"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["A catalyst speeds up a chemical reaction without being used up.","It is written over the arrow, for example $\\ce{MnO2}$ in making oxygen from $\\ce{H2O2}$.","It is recovered with the same mass and gives no extra product."]},"children":[]},"rv":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Show the answer"}},"children":["rv_t"]},"hook":{"type":"Text","props":{"content":"Back to the hook: the black powder is still there, with the same mass."},"children":[]},"next":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","hook","next","self","rv"]},"rv_t":{"type":"Text","props":{"content":"Weigh the $\\ce{MnO2}$, add it to $\\ce{H2O2}$, then filter, dry and weigh it again: it has the same mass as at the start. It was not used up, yet oxygen bubbled out fast, so it is a catalyst."},"children":[]},"self":{"type":"Text","props":{"content":"Can you explain how weighing shows that $\\ce{MnO2}$ is a catalyst?"},"children":[]}}},"title":"Summary"}],"title":"Catalyst","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 economic importance pp.6-7 ($\\ce{V2O5}$, iron and nickel as catalysts)","subtitle":"Faster reactions, nothing used up","objectives":["Define a catalyst: it speeds up a chemical reaction without being used up.","Show that the catalyst is written over the arrow in an equation.","Explain that the catalyst is recovered unchanged and does not make more product."],"concept_ids":["chem.catalyst"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good prediction. We can filter it, dry it and weigh it."},{"id":"b","feedback":"If it turned into oxygen, the powder would disappear. The oxygen comes from the hydrogen peroxide, and weighing shows the powder is still there."},{"id":"c","feedback":"That is a common idea, but a catalyst is not used up: weighing the powder after the reaction shows the same mass as at the start."}],"explanation":"Manganese dioxide is a catalyst: it speeds up the release of oxygen from hydrogen peroxide and is still there at the end, with the same mass. Filtering, drying and weighing it shows this."}},"s3":{"m":{"statement":"The catalyst is consumed in the reaction.","correction":"It is recovered with the same mass, so it can be used again. It also gives no extra product: the same oxygen forms, only faster."}},"s4":{"q":{"options":[{"id":"a","feedback":"Right. It is written over the arrow, so it is the catalyst."},{"id":"b","feedback":"The oxygen comes from $\\ce{KClO3}$, not from $\\ce{MnO2}$: $\\ce{MnO2}$ is written over the arrow, not with the reactants, so it is not used up."},{"id":"c","feedback":"KCl comes from $\\ce{KClO3}$. $\\ce{MnO2}$ is written over the arrow, not on the reactant side, so it does not turn into KCl."}],"explanation":"$\\ce{MnO2}$ is written over the arrow, so it is the catalyst: it speeds up the reaction and is recovered unchanged. The oxygen and the KCl both come from $\\ce{KClO3}$."},"fb":{"mistakes":[{"id":"m1","feedback":"Things before the arrow are reactants, and they get used up, but a catalyst is not used up."},{"id":"m2","feedback":"Things after the arrow are products, and a catalyst is not made in the reaction."}],"explanation":"The catalyst is written over the arrow, as $\\ce{MnO2}$ is."},"tf":{"explanation":"A catalyst changes how fast the product forms, not how much: the same amount of product forms, just faster.","feedback_true":"That is a common mix-up. The catalyst changes how fast, not how much.","feedback_false":"Right. The same product forms, only faster."}},"s5":{"next":{"body":"In Chapter 1: transition elements as catalysts in industry."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"توقّع حلو. نقدر نفلترها وننشّفها ونوزنها."},{"id":"b","feedback":"لو كانت بتتحوّل لـ oxygen، البودرة كانت هتختفي. إنما الـ oxygen طالع من الـ hydrogen peroxide، والوزن بيبيّن إن البودرة لسه موجودة."},{"id":"c","feedback":"دي فكرة منتشرة، لكن الـ catalyst مش بيتستهلك: لو وزنّا البودرة بعد الـ reaction هنلاقي نفس الكتلة اللي بدأنا بيها."}],"explanation":"الـ manganese dioxide ده catalyst: بيسرّع طلوع الـ oxygen من الـ hydrogen peroxide، وبيفضل موجود في الآخر بنفس الكتلة. ولو فلترناه ونشّفناه ووزنّاه هنشوف ده."}},"s3":{"m":{"statement":"الـ catalyst بيتستهلك في الـ reaction.","correction":"الـ catalyst بيرجع في الآخر بنفس الـ mass، فينفع تستخدمه تاني. وكمان مش بيدّي product زيادة: نفس كمية الـ oxygen بتتكوّن، الفرق إنها بتتكوّن أسرع."}},"s4":{"q":{"options":[{"id":"a","feedback":"صح. هو مكتوب فوق السهم، يبقى هو الـ catalyst."},{"id":"b","feedback":"الـ oxygen جاي من الـ $\\ce{KClO3}$، مش من الـ $\\ce{MnO2}$: الـ $\\ce{MnO2}$ مكتوب فوق السهم، مش مع الـ reactants، يعني مش بيتستهلك."},{"id":"c","feedback":"الـ KCl جاي من الـ $\\ce{KClO3}$. والـ $\\ce{MnO2}$ مكتوب فوق السهم، مش في ناحية الـ reactants، يعني مش بيتحوّل لـ KCl."}],"explanation":"الـ $\\ce{MnO2}$ مكتوب فوق السهم، يبقى هو الـ catalyst: بيسرّع الـ reaction وبيرجع زي ما هو من غير تغيير. والـ oxygen والـ KCl الاتنين جايين من الـ $\\ce{KClO3}$."},"fb":{"mistakes":[{"id":"m1","feedback":"اللي قبل السهم هما الـ reactants، ودول بيتستهلكوا، والـ catalyst مش بيتستهلك."},{"id":"m2","feedback":"اللي بعد السهم هما الـ products، والـ catalyst مش بيتكوّن، هو بيفضل زي ما هو."}],"explanation":"الـ catalyst بيتكتب فوق السهم، زي ما الـ $\\ce{MnO2}$ مكتوب."},"tf":{"explanation":"الـ catalyst بيغيّر سرعة تكوين الـ product، مش كميته: نفس كمية الـ product بتتكوّن، إنما أسرع.","feedback_true":"دي لخبطة منتشرة. الـ catalyst بيغيّر السرعة، مش الكمية.","feedback_false":"صح. نفس الـ product بيتكوّن، الفرق إنه بيتكوّن أسرع."}},"s5":{"next":{"body":"في الفصل الأول: الـ transition elements كـ catalysts في الصناعة."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":5,"is_basics":true,"lesson_no":5,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-magnetism-catalysis","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Magnetic properties and catalytic activity","duration_s":702.279,"start_s":308.6,"end_s":375,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.catalyst","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Catalyst","duration_s":53.33,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":64,"page_to":65,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.metal-properties","kind":"lesson","version":4,"catalog_version":3,"ord":88,"primary_concept_id":"chem.metal-properties","concepts":[{"concept_id":"chem.metal-properties","role":"primary"}],"title":"Properties of metals and non-metals","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It conducts electricity","correct":false},{"id":"b","text":"It is malleable: it can be hammered into sheets","correct":true},{"id":"c","text":"It is shiny","correct":false}],"question":"Predict: which property lets aluminum become foil?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"You can hammer aluminum into thin kitchen foil. Hit a lump of sulphur, and it breaks into powder."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Foil or powder?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Notice the word **most**. 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Use all the clues.","categories":[{"id":"metal","label":"Metal"},{"id":"non","label":"Non-metal"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Ductile","correct":true},{"id":"b","text":"Malleable","correct":false},{"id":"c","text":"Good conductor of heat","correct":false},{"id":"d","text":"Shiny","correct":false}],"question":"Heating coils need a metal that can be drawn into long, thin wires. Which property is that?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","c"]}}},"title":"Apply it"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Most metals are shiny, good conductors of heat and electricity, malleable and ductile, with high melting points.","Most non-metals are dull, poor conductors and brittle when solid; many are gases.","A metal is chosen for a use because of a property, e.g. copper in electric cables."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Key words"}},"children":[]},"mt":{"type":"Matching","props":{"pairs":[{"left":"Good conductor of electricity","right":"Electric cables"},{"left":"Malleable","right":"Kitchen foil"},{"left":"Ductile","right":"Heating-coil wires"}],"prompt":"Match each property to the use it explains."},"children":[]},"next":{"type":"Text","props":{"muted":true,"content":"Next in Chapter 1: some metals are too brittle to use pure. Watch for the reason each time."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","mt","ex","next","self"]},"self":{"type":"Text","props":{"content":"Can you explain why 'it conducts electricity, so it's a metal' can be wrong?"},"children":[]}}},"title":"Summary"}],"title":"Properties of metals and non-metals","minutes":5,"book_ref":"Prerequisite (preparatory science); used in Ch.1 economic importance p.5-7 (uses chosen by property) and 'Properties of Iron' (malleable, ductile)","subtitle":"Every use of a metal starts with a property","objectives":["Compare the physical properties of metals and non-metals.","Use a property (conductor, malleable, ductile, shiny) to explain why a metal is chosen for a use.","Avoid the trap 'it conducts electricity, so it must be a metal'."],"concept_ids":["chem.metal-properties"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Aluminum does conduct electricity, but conducting is not what lets a metal be hammered flat into foil."},{"id":"b","feedback":"Yes. Metals are usually malleable. Sulphur, a non-metal, is brittle."},{"id":"c","feedback":"Foil is shiny, but shine is about looks; it is not what lets a solid be hammered flat without breaking."}],"explanation":"Aluminum becomes foil because it is malleable: it can be hammered into thin sheets without breaking. Metals are usually malleable, while a solid non-metal such as sulphur is brittle."}},"s3":{"tf":{"explanation":"Judge by several properties (look, conducting, hammering, state), not by one.","feedback_true":"Not so fast. Graphite, a form of carbon, conducts electricity but is a non-metal. One property is not enough to decide.","feedback_false":"Right. Conducting alone does not prove it: graphite conducts but is a non-metal, and mercury is a metal although it is a liquid."}},"s4":{"c":{"items":[{"id":"x1","feedback":"Shiny, a conductor and hammered into sheets: these are all properties of metals."},{"id":"x2","feedback":"Breaking into powder and not conducting are properties of non-metals."},{"id":"x3","feedback":"That's the 'conducts, so it's a metal' trap. Graphite is a form of carbon, and carbon is a non-metal even though graphite conducts."},{"id":"x4","feedback":"Being liquid is unusual, but shiny and conducting are metal properties, and one property alone does not decide."},{"id":"x5","feedback":"A gas that does not conduct. The last row of the table shows that non-metals are often gases."}],"explanation":"Judge by several properties. Graphite conducts but is a non-metal; mercury is a liquid but is a metal."},"q":{"options":[{"id":"a","feedback":"Right. Ductile means it can be drawn into wires."},{"id":"b","feedback":"Malleable is about sheets, made by hammering, not about drawing a metal into wires."},{"id":"c","feedback":"Coils do get hot, but the question is about shape: being drawn into long, thin wires, not carrying heat."},{"id":"d","feedback":"Shine is about how it looks. The question is about pulling it into wires."}],"explanation":"Being drawn into long, thin wires is called ductile. Malleable is about being hammered into sheets; conducting heat and being shiny are other properties."}},"s5":{"ex":{"body":"Key words: **malleable**, **ductile**, **good conductor of electricity**, **brittle**."},"mt":{"explanation":"Cables carry current (conductor), foil is hammered flat (malleable), coil wires are drawn out long and thin (ductile)."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ aluminum فعلًا بيوصّل الكهربا، لكن التوصيل مش هو اللي بيخلّي الـ metal يتطرّق ويتفرد فويل."},{"id":"b","feedback":"أيوه. الـ metals عادةً بتبقى malleable. أما الـ sulphur، وهو non-metal، فهو brittle."},{"id":"c","feedback":"الفويل لامع فعلًا، لكن اللمعة بتخص المنظر؛ مش هي اللي بتخلّي الحاجة الـ solid تتطرّق وتتفرد من غير ما تتكسر."}],"explanation":"الـ aluminum بيتعمل فويل عشان هو malleable: ينفع يتطرّق لشرايح رفيعة من غير ما يتكسر. الـ metals عادةً بتبقى malleable، إنما الـ non-metal الـ solid زي الـ sulphur بيبقى brittle."}},"s3":{"tf":{"explanation":"احكم بأكتر من صفة (المنظر، التوصيل، الطَرق، الحالة)، مش بصفة واحدة.","feedback_true":"استنى شوية. الـ graphite، وهو شكل من أشكال الـ carbon، بيوصّل الكهربا لكنه non-metal. صفة واحدة مش كفاية عشان تحكم.","feedback_false":"مظبوط: التوصيل لوحده مش دليل. الـ graphite بيوصّل لكنه non-metal، والـ mercury metal مع إنه liquid."}},"s4":{"c":{"items":[{"id":"x1","feedback":"اللمعان والتوصيل والطَرق لشرايح من غير كسر: التلات صفات دول مع بعض هما نفس صفات الـ aluminum اللي بيتعمل فويل."},{"id":"x2","feedback":"التكسّر لبودرة وعدم التوصيل صفات brittle زي الـ sulphur الـ solid، مش صفات حاجة بتتطرّق وبتوصّل."},{"id":"x3","feedback":"ده فخ «بيوصّل، يبقى metal»: الـ Graphite شكل من أشكال الـ carbon، والتوصيل لوحده مش كفاية عشان تحكم على العنصر."},{"id":"x4","feedback":"إنه liquid دي حاجة مش معتادة، لكن باقي العلامات موجودة: shiny وبيوصّل، والحكم مايبقاش بصفة واحدة."},{"id":"x5","feedback":"غاز وتوصيله ضعيف: مفيهوش ولا صفة من اللمعان والتوصيل اللي عند الـ aluminum والـ mercury."}],"explanation":"احكم بأكتر من صفة. الـ Graphite بيوصّل لكنه non-metal؛ والـ mercury حالته liquid لكنه metal."},"q":{"options":[{"id":"a","feedback":"صح. ductile معناها إنه ينفع يتسحب لأسلاك."},{"id":"b","feedback":"الـ malleable ليها علاقة بالشرايح اللي بتيجي من الطَرق، مش بسحب الـ metal لأسلاك."},{"id":"c","feedback":"الملفات فعلًا بتسخن، لكن السؤال عن الشكل: إنه يتسحب لأسلاك طويلة ورفيعة، مش عن توصيل الحرارة."},{"id":"d","feedback":"اللمعة بتخص المنظر. والسؤال عن إنك تسحب الـ metal لأسلاك."}],"explanation":"إن الـ metal يتسحب لأسلاك طويلة ورفيعة اسمه ductile. الـ malleable ليها علاقة بالطَرق لشرايح؛ وتوصيل الحرارة واللمعة دول صفات تانية."}},"s5":{"ex":{"body":"الكلمات المهمة: **malleable**، **ductile**، **good conductor of electricity**، **brittle**."},"mt":{"explanation":"الكابلات بتنقل التيار (conductor)، والفويل بيتطرّق ويتفرد (malleable)، وأسلاك الملفات بتتسحب طويلة ورفيعة (ductile)."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":6,"is_basics":true,"lesson_no":6,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":223.2,"end_s":299.7,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.metal-properties","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Properties of metals and non-metals","duration_s":44.71,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic 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So is copper (II) sulphate, $CuSO_4$, and nobody eats it."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Not all salts are for food"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Acid","definition":"A substance that gives positive hydrogen ions ($H^+$) when dissolved in water."},"children":[]},"t":{"type":"Text","props":{"content":"Acids taste sour and turn litmus red. Never taste them in the lab!"},"children":[]},"ion":{"type":"Text","props":{"content":"An **ion** is an atom, or a group of atoms, with an electric charge. You'll study ions later in Chapter 1."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["hydrochloric acid","$HCl$","chlorides"],["sulphuric acid","$H_2SO_4$","sulphates"],["nitric acid","$HNO_3$","nitrates"]],"caption":"Common acids","headers":["Acid","Formula","Its salts are called"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","ion","tab","t"]}}},"title":"Acids"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Base","definition":"A substance that reacts with an acid to give a salt and water."},"children":[]},"n":{"type":"Text","props":{"content":"You'll meet metal oxides as bases again in the next lesson."},"children":[]},"t":{"type":"Text","props":{"content":"Many metal oxides and metal hydroxides are bases. Examples: copper (II) oxide, CuO, and magnesium hydroxide, $Mg(OH)_2$."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["copper (II) oxide","CuO","metal oxide"],["magnesium hydroxide","$Mg(OH)_2$","metal hydroxide"]],"caption":"Two bases","headers":["Base","Formula","Type"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","t","tab","n"]}}},"title":"Bases"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Alkali","definition":"A base that dissolves in water, giving hydroxide ions ($OH^-$)."},"children":[]},"t":{"type":"Text","props":{"content":"Examples: sodium hydroxide, NaOH, and ammonium hydroxide, $NH_4OH$. Alkalis turn litmus blue."},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"NaOH is an acid, because its formula contains H."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","t","tf"]}}},"title":"Alkalis"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{NaOH + HCl ->}\\\\ \\ce{NaCl + H2O}\\end{gathered}","caption":"An alkali and an acid give a salt and water"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Salt","definition":"A compound formed when the hydrogen of an acid is replaced by a metal (or ammonium)."},"children":[]},"t":{"type":"Text","props":{"content":"Naming rule: the metal's name from the base + the ending from the acid. Copper (II) oxide + sulphuric acid → copper (II) sulphate + water."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","k","t"]}}},"title":"Acid + base → salt + water"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"zncl2","text":"$ZnCl_2$, zinc chloride"},{"id":"mnso4","text":"$MnSO_4$, manganese (II) sulphate"},{"id":"kno3","text":"$KNO_3$, potassium nitrate"},{"id":"na2so4","text":"$Na_2SO_4$, sodium sulphate"},{"id":"nh4cl","text":"$NH_4Cl$, ammonium chloride"}],"answer":{"hcl":["zncl2","nh4cl"],"hno3":["kno3"],"h2so4":["mnso4","na2so4"]},"prompt":"Which acid does each salt come from?","categories":[{"id":"hcl","label":"Hydrochloric acid"},{"id":"h2so4","label":"Sulphuric acid"},{"id":"hno3","label":"Nitric acid"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"ZnO and $HNO_3$","correct":true},{"id":"b","text":"ZnO and $H_2SO_4$","correct":false},{"id":"c","text":"NaOH and $HNO_3$","correct":false},{"id":"d","text":"ZnO and HCl","correct":false}],"question":"Which pair reacts to give zinc nitrate and water?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Name the parent acid"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Acids give hydrogen ions, $H^+$, in water: HCl, $H_2SO_4$, $HNO_3$.","Bases react with acids to give a salt and water. Many metal oxides and hydroxides are bases.","Alkalis are bases that dissolve in water, giving $OH^-$: NaOH, $NH_4OH$.","Chlorides, sulphates and nitrates come from HCl, $H_2SO_4$ and $HNO_3$."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Key words"}},"children":[]},"rv":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Show the answer"}},"children":["rv_t"]},"hook":{"type":"Text","props":{"content":"Back to the hook: NaCl and $CuSO_4$ are both salts. In each, a metal replaced the hydrogen of an acid."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","hook","ex","self","rv"]},"rv_t":{"type":"Text","props":{"content":"In $CuSO_4$, copper has replaced the hydrogen of sulphuric acid, $H_2SO_4$. The $SO_4$ group comes from the acid, so the salt is a sulphate."},"children":[]},"self":{"type":"Text","props":{"content":"Can you explain why $CuSO_4$ is a salt of sulphuric acid?"},"children":[]}}},"title":"Summary"}],"title":"Acids, bases and salts","minutes":6,"book_ref":"Prerequisite (preparatory chemistry); used for salts named in Ch.1 economic importance p.6-7 (e.g. $MnSO_4$, $CuSO_4$) and for the reactions of iron oxides with acids","subtitle":"What makes copper (II) sulphate a salt?","objectives":["Define an acid, a base and an alkali, and name common examples.","State that an acid and a base react to give a salt and water.","Name a salt from its metal and its acid: chloride, sulphate, nitrate."],"concept_ids":["chem.acids-bases-salts"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good guess. Next, we test it: where the metal sits, and what it replaced."},{"id":"b","feedback":"Never taste lab chemicals! Taste is not what makes a salt; what makes a salt shows in the formula."},{"id":"c","feedback":"Sugar dissolves too, and it is not a salt, so dissolving is not what makes a salt."}],"explanation":"In both, a metal has taken the place of the hydrogen of an acid: Na with the Cl of hydrochloric acid, Cu with the $SO_4$ of sulphuric acid. That is what makes them salts, not their taste or dissolving."}},"s4":{"tf":{"explanation":"NaOH is an alkali, not an acid: its H is part of the OH group, and in water it gives hydroxide ions ($OH^-$).","feedback_true":"That's the 'H in the formula means acid' trap. In NaOH, the H is part of the OH group, and in water NaOH gives $OH^-$ ions.","feedback_false":"Correct. The H is inside the OH group. NaOH gives $OH^-$ ions, so it is an alkali."}},"s6":{"c":{"items":[{"id":"zncl2","feedback":"Chlorides come from the acid whose formula has Cl: HCl."},{"id":"mnso4","feedback":"The ending 'sulphate' means the $SO_4$ group, which comes from $H_2SO_4$."},{"id":"kno3","feedback":"Nitrates have the $NO_3$ group, and $HNO_3$ is the acid that contains it."},{"id":"na2so4","feedback":"The group here is $SO_4$, and it comes from $H_2SO_4$."},{"id":"nh4cl","feedback":"Ammonium can replace hydrogen too; the other part, Cl, comes from HCl."}],"explanation":"Chlorides ← HCl; sulphates ← $H_2SO_4$; nitrates ← $HNO_3$."},"q":{"options":[{"id":"a","feedback":"Right. The base gives the metal, zinc; nitric acid gives the ending, nitrate."},{"id":"b","feedback":"The zinc part is right, but $H_2SO_4$ gives sulphates, not nitrates."},{"id":"c","feedback":"The acid part is right, but the salt takes its metal from the base, and NaOH gives sodium, not zinc."},{"id":"d","feedback":"HCl gives chlorides, not nitrates."}],"explanation":"Zinc nitrate takes its metal, zinc, from the base ZnO, and its ending, nitrate, from nitric acid, $HNO_3$. A base and an acid give a salt and water."}},"s7":{"ex":{"body":"Key words: **acid**, **base**, **alkali**, **salt and water**, **chloride**, **sulphate**, **nitrate**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تخمين حلو. يلا نختبره ونشوف الـ metal قاعد فين وخد مكان إيه."},{"id":"b","feedback":"إوعى تدوق كيماويات المعمل أبدًا! الطعم مش هو اللي بيخلي المادة salt، اللي بيحدد ده هو الـ formula."},{"id":"c","feedback":"السكر كمان بيدوب في الماية، ومع كده مش salt، فالذوبان مش هو اللي بيخليهم salts."}],"explanation":"في الاتنين فيه metal واخد مكان الـ hydrogen بتاع acid: الـ Na مع الـ Cl بتاع الـ hydrochloric acid، والـ Cu مع الـ $SO_4$ بتاع الـ sulphuric acid. وده اللي بيخليهم salts، مش الطعم ولا الذوبان."}},"s4":{"tf":{"explanation":"الـ NaOH ده alkali مش acid: الـ H بتاعه جزء من الـ OH group، وفي الماية بيدّي hydroxide ions ($OH^-$).","feedback_true":"دي فخ «طالما فيه H في الـ formula يبقى acid». في الـ NaOH، الـ H جزء من الـ OH group، والـ NaOH بيدي $OH^-$ ions في الماية.","feedback_false":"مظبوط. الـ H هنا جوه الـ OH group. الـ NaOH بيدي $OH^-$ ions، يعني هو alkali."}},"s6":{"c":{"items":[{"id":"zncl2","feedback":"الـ chlorides جاية من الـ acid اللي في الـ formula بتاعته Cl: الـ HCl."},{"id":"mnso4","feedback":"النهاية 'sulphate' معناها $SO_4$ group، فالـ acid بتاعها لازم يكون فيه $SO_4$، وده الـ $H_2SO_4$."},{"id":"kno3","feedback":"الـ nitrates فيها الـ $NO_3$ group، والـ $HNO_3$ هو الـ acid اللي فيه الـ group دي."},{"id":"na2so4","feedback":"الـ group هنا $SO_4$، وده جاي من الـ $H_2SO_4$."},{"id":"nh4cl","feedback":"الـ ammonium كمان يقدر ياخد مكان الـ hydrogen، والجزء التاني، الـ Cl، جاي من الـ HCl."}],"explanation":"الـ chlorides جاية من HCl، والـ sulphates جاية من $H_2SO_4$، والـ nitrates جاية من $HNO_3$."},"q":{"options":[{"id":"a","feedback":"صح. الـ base بيدي الـ metal، اللي هو الـ zinc، والـ nitric acid بيدي النهاية، nitrate."},{"id":"b","feedback":"جزء الـ zinc صح، لكن الـ $H_2SO_4$ بيدي sulphates، مش nitrates."},{"id":"c","feedback":"جزء الـ acid صح، لكن الـ salt بياخد الـ metal بتاعه من الـ base، والـ NaOH بيدي sodium مش zinc."},{"id":"d","feedback":"الـ HCl بيدي chlorides، مش nitrates."}],"explanation":"الـ zinc nitrate بياخد الـ metal بتاعه، الـ zinc، من الـ base اللي هو ZnO، ونهاية اسمه، nitrate، من الـ nitric acid، $HNO_3$. والـ base مع الـ acid بيدّوا salt و water."}},"s7":{"ex":{"body":"كلمات مهمة: **acid**، **base**، **alkali**، **salt and water**، **chloride**، **sulphate**، **nitrate**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":7,"is_basics":true,"lesson_no":7,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-chem.acids-bases-salts","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Acids, bases and salts: from zero","duration_s":334.64,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.acids-bases-salts","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Acids, bases and salts","duration_s":42.51,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":43,"page_to":43,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.lesson-chem.oxides","kind":"lesson","version":2,"catalog_version":3,"ord":92,"primary_concept_id":"chem.oxides","concepts":[{"concept_id":"chem.oxides","role":"primary"}],"title":"Acidic and basic oxides","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Yes, it fizzes, because rust contains iron","correct":false},{"id":"b","text":"No, it dissolves without giving a gas","correct":true},{"id":"c","text":"No, nothing happens to rust in an acid","correct":false}],"question":"Predict: will rust fizz and give hydrogen gas in the acid, like iron metal?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Rust is an iron oxide. Dilute hydrochloric acid can dissolve it. Iron metal fizzes in this acid, giving hydrogen gas."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Acid vs rust"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{CuO + H2SO4 -> CuSO4 + H2O}","caption":"copper (II) oxide + sulphuric acid → copper (II) sulphate + water"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Basic oxide","definition":"A metal oxide that reacts with an acid to give a salt and water."},"children":[]},"t":{"type":"Text","props":{"content":"A basic oxide acts like a base. So it neutralizes the acid: salt and water, no gas."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"o","from":"m","label":"+ oxygen"},{"to":"s","from":"o","label":"+ acid"}],"nodes":[{"id":"m","label":"Metal"},{"id":"o","label":"Metal oxide (basic oxide)"},{"id":"s","label":"Salt + water"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","fd","t"]}}},"title":"Basic oxides"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"a":{"type":"Card","props":{"tone":"warning","title":"Acidic oxides"},"children":["at"]},"b":{"type":"Card","props":{"tone":"info","title":"Basic oxides"},"children":["bt"]},"f":{"type":"Formula","props":{"latex":"\\ce{SO3 + H2O -> H2SO4}","caption":"sulphur trioxide + water → sulphuric acid"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Acidic oxide","definition":"A non-metal oxide that dissolves in water to give an acid."},"children":[]},"m":{"type":"Callout","props":{"variant":"warning"},"children":[]},"at":{"type":"Text","props":{"content":"Most non-metal oxides: $CO_2$, $SO_3$"},"children":[]},"bt":{"type":"Text","props":{"content":"Most metal oxides: $Na_2O$, MgO, CuO"},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["b","a"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","cols","m"]}}},"title":"Acidic oxides"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"k2o","text":"$K_2O$"},{"id":"cao","text":"CaO"},{"id":"feo","text":"FeO"},{"id":"so2","text":"$SO_2$"},{"id":"p2o5","text":"$P_2O_5$"}],"answer":{"basic":["k2o","cao","feo"],"acidic":["so2","p2o5"]},"prompt":"Basic oxide or acidic oxide?","categories":[{"id":"basic","label":"Basic oxide"},{"id":"acidic","label":"Acidic oxide"}]},"children":[]},"fb":{"type":"FillBlank","props":{"text":"A basic oxide reacts with an acid to give a salt and ___.","answers":[["water","h2o"]],"mistakes":[{"id":"m1","blank":0,"answer":"hydrogen"},{"id":"m2","blank":0,"answer":"h2"},{"id":"m3","blank":0,"answer":"oxygen"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","fb"]}}},"title":"Classify and predict"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Most metal oxides are basic oxides: basic oxide + acid → salt + water.","Most non-metal oxides are acidic oxides: they dissolve in water to give acids.","Rust is an iron oxide, a basic oxide, so an acid dissolves it."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Key words"}},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_f","ans_t"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","ex","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why an acid dissolves copper (II) oxide but gives no hydrogen gas?"},"children":[]},"ans_f":{"type":"Formula","props":{"latex":"\\ce{CuO + H2SO4 -> CuSO4 + H2O}","caption":"copper (II) oxide + sulphuric acid → copper (II) sulphate + water"},"children":[]},"ans_t":{"type":"Text","props":{"content":"Copper (II) oxide is a basic oxide, not free metal: it neutralizes the acid to give a salt and water. The acid's H joins the oxide's O to form water, so no gas is given off."},"children":[]}}},"title":"Summary"}],"title":"Acidic and basic oxides","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used for oxides in Ch.1 (rusting, the chromium oxide layer p.6, and the iron oxides FeO, $Fe_2O_3$)","subtitle":"Why an acid can dissolve rust","objectives":["State that most metal oxides are basic oxides: they react with acids to give a salt and water.","State that most non-metal oxides are acidic oxides: they dissolve in water to give acids.","Classify an oxide as basic or acidic from its element."],"concept_ids":["chem.oxides"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Iron metal gives hydrogen, but rust is iron oxide, not free iron."},{"id":"b","feedback":"Good prediction. The acid's hydrogen ends up in another product. Let's find out which."},{"id":"c","feedback":"The acid does dissolve rust, as you read above, so something does happen to it."}],"explanation":"Rust dissolves in the acid without giving off hydrogen gas. Rust is an iron oxide, not free iron metal: the acid's hydrogen combines with the oxide's oxygen to form water, and a salt forms with it."}},"s3":{"m":{"body":"Say **most**. A few metal oxides, such as $Al_2O_3$, react with acids and with bases too."}},"s4":{"c":{"items":[{"id":"k2o","feedback":"Potassium is a metal, so $K_2O$ is a metal oxide."},{"id":"cao","feedback":"Calcium is a metal, so CaO is a metal oxide."},{"id":"feo","feedback":"Iron is a metal, so FeO is a metal oxide."},{"id":"so2","feedback":"Sulphur is a non-metal, so $SO_2$ is a non-metal oxide."},{"id":"p2o5","feedback":"Phosphorus is a non-metal, so $P_2O_5$ is a non-metal oxide."}],"explanation":"Metal oxides ($K_2O$, CaO, FeO) are basic. Non-metal oxides ($SO_2$, $P_2O_5$) are acidic."},"fb":{"mistakes":[{"id":"m1","feedback":"That's the metal + acid reaction, and an oxide has no free metal: the acid's H joins the oxide's O instead."},{"id":"m2","feedback":"That's the metal + acid reaction, and an oxide has no free metal: the acid's H joins the oxide's O instead."},{"id":"m3","feedback":"No gas is given off here: the acid's H joins the oxide's O."}],"explanation":"The oxide's O and the acid's H form water."}},"s5":{"ex":{"body":"Key words: **basic oxide**, **acidic oxide**, **salt and water**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ iron metal بيدي hydrogen، لكن الـ rust ده iron oxide، مش iron حر."},{"id":"b","feedback":"توقع حلو. الـ hydrogen بتاع الـ acid بيروح في ناتج تاني. يلا نشوف أنهي ناتج."},{"id":"c","feedback":"الـ acid فعلًا بيدوّب الـ rust، زي ما قريت فوق، يعني فيه حاجة بتحصله."}],"explanation":"الـ rust بيدوب في الـ acid من غير ما يطلّع hydrogen gas. عشان الـ rust ده iron oxide، مش iron metal حر: الـ hydrogen بتاع الـ acid بيتحد مع الـ oxygen اللي في الـ oxide ويكوّن مية، ومعاها بيتكوّن salt."}},"s3":{"m":{"body":"قول **most**. فيه شوية metal oxides، زي $Al_2O_3$، بتتفاعل مع الـ acids ومع الـ bases كمان."}},"s4":{"c":{"items":[{"id":"k2o","feedback":"الـ potassium ده metal، فالـ $K_2O$ ده metal oxide."},{"id":"cao","feedback":"الـ calcium ده metal، فالـ CaO ده metal oxide."},{"id":"feo","feedback":"الـ iron ده metal، فالـ FeO ده metal oxide."},{"id":"so2","feedback":"الـ sulphur ده non-metal، فالـ $SO_2$ ده non-metal oxide."},{"id":"p2o5","feedback":"الـ phosphorus ده non-metal، فالـ $P_2O_5$ ده non-metal oxide."}],"explanation":"الـ metal oxides اللي هنا ($K_2O$ و CaO و FeO) basic. والـ non-metal oxides اللي هنا ($SO_2$ و $P_2O_5$) acidic."},"fb":{"mistakes":[{"id":"m1","feedback":"ده تفاعل الـ metal + acid، والـ oxide مفيهوش metal حر: الـ H بتاع الـ acid بيتحد مع الـ O بتاع الـ oxide بدل كده."},{"id":"m2","feedback":"ده تفاعل الـ metal + acid، والـ oxide مفيهوش metal حر: الـ H بتاع الـ acid بيتحد مع الـ O بتاع الـ oxide بدل كده."},{"id":"m3","feedback":"مفيش gas بيطلع هنا: الـ H بتاع الـ acid بيتحد مع الـ O بتاع الـ oxide."}],"explanation":"الـ O بتاع الـ oxide والـ H بتاع الـ acid بيكوّنوا water."}},"s5":{"ex":{"body":"الكلمات المهمة: **basic oxide**، **acidic oxide**، **salt and water**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":8,"is_basics":true,"lesson_no":8,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-chem.oxides","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Acidic and basic oxides: from zero","duration_s":275.73,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.oxides","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Acidic and basic oxides","duration_s":47.1,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.rusting-corrosion","kind":"lesson","version":2,"catalog_version":3,"ord":94,"primary_concept_id":"chem.rusting-corrosion","concepts":[{"concept_id":"chem.rusting-corrosion","role":"primary"}],"title":"Rusting and corrosion","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"size":"lg","content":"An iron nail in a wet garden turns red-brown in weeks. A gold ring can last for centuries. What happens to the nail?"},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Iron nail in a wet garden","turns red-brown in weeks"],["Gold ring","can last for centuries"]],"headers":["Object","What you see"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","tb"]}}},"title":"Nail vs ring"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Corrosion","definition":"The slow reaction of a metal with substances in the air, like oxygen and moisture, that wears the metal away."},"children":[]},"t":{"type":"Text","props":{"content":"**Rusting** is the corrosion of iron. Rust is a hydrated iron (III) oxide. Some metals corrode quickly, like iron; gold hardly at all."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"rust","from":"fe","label":"slow reaction with oxygen and moisture"}],"nodes":[{"id":"fe","label":"Iron"},{"id":"rust","label":"Rust: hydrated iron (III) oxide"}],"layout":"horizontal","caption":"Rusting is the corrosion of iron"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","t","fd"]}}},"title":"Corrosion"},{"id":"s3","kind":"interact","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 360 240\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><path d=\"M30 30 L30 180 Q30 200 60 200 Q90 200 90 180 L90 30\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><rect x=\"33\" y=\"165\" width=\"54\" height=\"30\" rx=\"8\" fill=\"#f8fafc\" fill-opacity=\"0.35\"/><line x1=\"30\" y1=\"44\" x2=\"90\" y2=\"44\" stroke=\"#e2e8f0\" stroke-width=\"3\"/><line x1=\"60\" y1=\"75\" x2=\"60\" y2=\"160\" stroke=\"#cbd5e1\" stroke-width=\"5\" stroke-linecap=\"round\"/><line x1=\"52\" y1=\"75\" x2=\"68\" y2=\"75\" stroke=\"#cbd5e1\" stroke-width=\"5\" stroke-linecap=\"round\"/><text x=\"60\" y=\"225\" text-anchor=\"middle\" font-size=\"16\" font-weight=\"700\" fill=\"#e2e8f0\">A</text><path d=\"M145 30 L145 180 Q145 200 175 200 Q205 200 205 180 L205 30\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><rect x=\"147\" y=\"70\" width=\"56\" height=\"128\" fill=\"#60a5fa\" fill-opacity=\"0.3\"/><rect x=\"147\" y=\"60\" width=\"56\" height=\"10\" fill=\"#fbbf24\" fill-opacity=\"0.55\"/><line x1=\"175\" y1=\"75\" x2=\"175\" y2=\"160\" stroke=\"#cbd5e1\" stroke-width=\"5\" stroke-linecap=\"round\"/><line x1=\"167\" y1=\"75\" x2=\"183\" y2=\"75\" stroke=\"#cbd5e1\" stroke-width=\"5\" stroke-linecap=\"round\"/><text x=\"175\" y=\"225\" text-anchor=\"middle\" font-size=\"16\" font-weight=\"700\" fill=\"#e2e8f0\">B</text><path d=\"M260 30 L260 180 Q260 200 290 200 Q320 200 320 180 L320 30\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><rect x=\"262\" y=\"120\" width=\"56\" height=\"78\" fill=\"#60a5fa\" fill-opacity=\"0.3\"/><line x1=\"290\" y1=\"75\" x2=\"290\" y2=\"160\" stroke=\"#cbd5e1\" stroke-width=\"5\" stroke-linecap=\"round\"/><line x1=\"282\" y1=\"75\" x2=\"298\" y2=\"75\" stroke=\"#cbd5e1\" stroke-width=\"5\" stroke-linecap=\"round\"/><text x=\"290\" y=\"225\" text-anchor=\"middle\" font-size=\"16\" font-weight=\"700\" fill=\"#e2e8f0\">C</text></svg>","caption":"A: dry air (a drying agent, closed tube). B: boiled water under a layer of oil. C: air and water.","max_width":360},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A: dry air","correct":false},{"id":"b","text":"B: boiled water under oil","correct":false},{"id":"c","text":"C: air and water","correct":true}],"question":"Predict: after a week, which nail rusts?"},"children":[]},"r":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"See the result"}},"children":["res","res2"]},"res":{"type":"Text","props":{"content":"Only nail C rusts. Rusting needs **oxygen and moisture together**."},"children":[]},"res2":{"type":"Text","props":{"content":"Rust is **porous** (full of tiny holes) and flakes off. So air and water reach fresh iron below, and rusting continues."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","q","r"]}}},"title":"Which nail rusts?"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"g":{"type":"Card","props":{"tone":"brand","title":"Galvanizing"},"children":["gt"]},"p":{"type":"Card","props":{"tone":"info","title":"Paint, oil, grease"},"children":["pt"]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"a","from":"c"},{"to":"n","from":"a"}],"nodes":[{"id":"c","label":"Coating on the iron"},{"id":"a","label":"Oxygen and moisture kept away"},{"id":"n","label":"Rusting is slowed"}],"layout":"horizontal"},"children":[]},"gt":{"type":"Text","props":{"content":"Coating iron with a layer of zinc."},"children":[]},"pl":{"type":"Card","props":{"tone":"success","title":"Plating"},"children":["plt"]},"pt":{"type":"Text","props":{"content":"A barrier layer on bridges, car bodies and chains."},"children":[]},"t2":{"type":"Text","props":{"content":"Each coating keeps oxygen and moisture away from the iron."},"children":[]},"plt":{"type":"Text","props":{"content":"Covering iron with a thin layer of another metal that resists corrosion."},"children":[]},"cols":{"type":"Columns","props":{"columns":3},"children":["p","g","pl"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["cols","t2","fd"]}}},"title":"How to stop rusting"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"g","text":"A galvanized iron bucket left in the rain"},{"id":"s","text":"A painted car door with a deep scratch, in humid air"},{"id":"d","text":"An iron key kept in a dry, closed box with a drying agent"},{"id":"w","text":"An old iron gate in a wet garden, with flaking rust"}],"answer":{"no":["g","d"],"yes":["s","w"]},"prompt":"Will the iron rust quickly?","categories":[{"id":"yes","label":"Rusts quickly"},{"id":"no","label":"Protected"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The oil keeps oxygen and moisture away from the iron","correct":true},{"id":"b","text":"The oil reacts with the rust and removes it","correct":false},{"id":"c","text":"Oil makes iron a less active metal","correct":false},{"id":"d","text":"A moving chain is too fast to rust","correct":false}],"question":"A bicycle chain is kept oiled. Why does it rust slowly?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","c"]}}},"title":"Apply it"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Corrosion: a metal slowly reacts with oxygen and moisture in air. Rusting is the corrosion of iron.","Rust is porous and flakes off, so rusting continues.","Paint, oil, galvanizing (zinc) and plating with another metal keep air and moisture away."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Key words"}},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_t"]},"next":{"type":"Text","props":{"muted":true,"content":"Next in Chapter 1: chromium is a very active metal, yet it resists the air. Keep 'porous' in mind."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","ex","next","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why a scratch in the paint lets a car door rust?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"At the scratch the paint is gone, so air and moisture reach the bare iron. Rusting needs oxygen and moisture together, so the iron rusts there."},"children":[]}}},"title":"Summary"}],"title":"Rusting and corrosion","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 economic importance p.6-7 (resisting corrosion, galvanizing, plating) and the chromium oxide layer p.6","subtitle":"What air and water do to iron, and how we stop it","objectives":["Describe rusting as the corrosion of iron by oxygen and moisture in air.","Explain why rusting continues: rust is porous and flakes off.","Explain how coatings (paint, oil, zinc in galvanizing, plating with another metal) protect iron."],"concept_ids":["chem.rusting-corrosion"]},"layer":{"steps":{"s3":{"q":{"options":[{"id":"a","feedback":"Air has oxygen, but here the air is dry, and oxygen alone is not enough."},{"id":"b","feedback":"That's the 'water alone causes rust' idea. Boiling removes air from water, and the oil keeps air out, so oxygen is missing."},{"id":"c","feedback":"Right. Iron rusts only when oxygen and water are both present."}],"explanation":"Nail C, in air and water, is the one that rusts. Rusting needs oxygen and moisture together: tube A has dry air, and in tube B boiling removed the air from the water and the oil keeps air out."}},"s5":{"c":{"items":[{"id":"g","feedback":"The zinc layer covers the iron, so water and oxygen cannot reach it."},{"id":"s","feedback":"At the scratch the paint is gone, so air and moisture reach the bare iron."},{"id":"d","feedback":"Like tube A, the box has oxygen but no moisture."},{"id":"w","feedback":"The rust is porous and flakes off, so it does not keep air and water away from the iron below."}],"explanation":"Rust needs oxygen and moisture together. Coatings and dry air protect; scratches and porous rust do not."},"q":{"options":[{"id":"a","feedback":"Right. No air and water on the surface, no rusting."},{"id":"b","feedback":"Oil is a barrier, not a rust remover."},{"id":"c","feedback":"The iron itself doesn't change: oil does not make it a less active metal."},{"id":"d","feedback":"Rusting is a reaction with air and water, and moving does not stop that reaction."}],"explanation":"The oil coats the chain and keeps oxygen and moisture away from the iron surface, so rusting is slow. The oil does not remove rust or change the iron itself."}},"s6":{"ex":{"body":"Key words: **oxygen and moisture**, **porous**, **galvanizing**, **resists corrosion**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s3":{"q":{"options":[{"id":"a","feedback":"الهوا فيه oxygen، لكن الهوا هنا ناشف، والـ oxygen لوحده مش كفاية."},{"id":"b","feedback":"دي فكرة «الماية لوحدها بتعمل rust». الغليان بيطرد الهوا من الماية، والزيت بيمنع الهوا يدخل، فالـ oxygen ناقص."},{"id":"c","feedback":"صح. الـ iron مش بيحصله rusting غير لما الـ oxygen والماية يكونوا موجودين الاتنين مع بعض."}],"explanation":"المسمار C، اللي في هوا وماية، هو اللي بيصدّي. الـ rusting محتاج الـ oxygen والرطوبة مع بعض: الأنبوبة A فيها هوا ناشف، وفي الأنبوبة B الغليان طرد الهوا من الماية والزيت بيمنع الهوا يدخل."}},"s5":{"c":{"items":[{"id":"g","feedback":"طبقة الـ zinc مغطية الـ iron، فالماية والـ oxygen مش بيوصلوله."},{"id":"s","feedback":"عند الخدش الدهان راح، فالهوا والرطوبة بيوصلوا للـ iron المكشوف هناك."},{"id":"d","feedback":"زي الأنبوبة A: العلبة فيها oxygen لكن مفيهاش moisture."},{"id":"w","feedback":"الـ rust ده porous وبيتقشّر، فمش بيبعد الهوا والماية عن الـ iron اللي تحته."}],"explanation":"الـ rust محتاج oxygen و moisture مع بعض. الطبقات اللي بتغطي الـ iron والهوا الناشف بيحموه؛ إنما الخدوش والـ rust الـ porous لأ."},"q":{"options":[{"id":"a","feedback":"صح. مفيش هوا وماية على السطح، يبقى مفيش rusting."},{"id":"b","feedback":"الزيت حاجز، مش مزيل للـ rust: مش بيتفاعل مع الـ rust ولا بيشيله."},{"id":"c","feedback":"الزيت مش بيغيّر الـ iron نفسه، فنشاط الـ iron هو هو."},{"id":"d","feedback":"الـ rusting ده تفاعل مع الهوا والماية، والحركة مش بتوقّف التفاعل ده."}],"explanation":"الزيت بيغطي الجنزير وبيبعد الـ oxygen والرطوبة عن سطح الـ iron، عشان كده الـ rusting بيبقى بطيء. الزيت مش بيشيل الـ rust ولا بيغيّر الـ iron نفسه."}},"s6":{"ex":{"body":"الكلمات المهمة: **oxygen and moisture**، **porous**، **galvanizing**، **resists corrosion**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":9,"is_basics":true,"lesson_no":9,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-chem.rusting-corrosion","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Rusting and corrosion: from zero","duration_s":320.31,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.rusting-corrosion","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Rusting and corrosion","duration_s":46.68,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-redox.basic","kind":"lesson","version":3,"catalog_version":3,"ord":96,"primary_concept_id":"redox.basic","concepts":[{"concept_id":"redox.basic","role":"primary"}],"title":"Oxidation and reduction by oxygen","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It took oxygen away from it","correct":true},{"id":"b","text":"It added hydrogen to the copper","correct":false},{"id":"c","text":"It just cleaned off soot","correct":false}],"question":"Predict: what did the hydrogen do to the black solid?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Heat a copper wire in a flame and it turns black. Heat the black wire in hydrogen, and the copper comes back."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Black, then pink again"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{2Cu + O2 ->[\\Delta] 2CuO}","caption":"Copper gains oxygen: copper is oxidized"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Oxidation","definition":"Gain of oxygen, or loss of hydrogen."},"children":[]},"t":{"type":"Text","props":{"content":"Burning and rusting are oxidation too: a substance gains oxygen."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t"]}}},"title":"Oxidation"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{CuO + H2 ->[\\Delta] Cu + H2O}"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Reduction","definition":"Loss of oxygen, or gain of hydrogen."},"children":[]},"t":{"type":"Text","props":{"content":"Oxidation and reduction happen together. Here $CuO$ loses oxygen while $H_2$ gains it."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"cu","from":"cuo","label":"loses oxygen: reduced"},{"to":"h2o","from":"h2","label":"gains oxygen: oxidized"}],"nodes":[{"id":"cuo","label":"$CuO$"},{"id":"cu","label":"$Cu$"},{"id":"h2","label":"$H_2$"},{"id":"h2o","label":"$H_2O$"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","fd","t"]}}},"title":"Reduction"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"a":{"type":"Text","props":{"content":"$H_2$ takes the oxygen: it is the **reducing agent**. $CuO$ gives the oxygen: it is the **oxidizing agent**."},"children":[]},"m":{"type":"TrueFalse","props":{"answer":false,"statement":"The oxidizing agent is the substance that gets oxidized."},"children":[]},"t":{"type":"Text","props":{"content":"Contrast: $H_2$ is oxidized to water, yet we call it the reducing agent."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Oxidizing agent (e.g. CuO)","supplies oxygen","it is reduced"],["Reducing agent (e.g. $H_2$, CO, C)","takes oxygen away","it is oxidized"]],"headers":["","What it does","What happens to it"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["a","tab","m","t"]}}},"title":"The two agents"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Mg","correct":true},{"id":"b","text":"$CO_2$","correct":false},{"id":"c","text":"MgO","correct":false},{"id":"d","text":"C","correct":false}],"question":"In $\\ce{2Mg + CO2 -> 2MgO + C}$, which substance is the reducing agent?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"In $\\ce{H2S + Cl2 -> 2HCl + S}$, $H_2S$ loses hydrogen, so $H_2S$ is ___.","answers":[["oxidized","oxidised"]],"mistakes":[{"id":"m1","blank":0,"answer":"reduced"},{"id":"m2","blank":0,"answer":"the oxidizing agent"}]},"children":[]},"q2":{"type":"MCQ","props":{"options":[{"id":"a","text":"It is oxidized, so it is the reducing agent","correct":true},{"id":"b","text":"It is reduced, so it is the oxidizing agent","correct":false},{"id":"c","text":"It is oxidized, so it is the oxidizing agent","correct":false}],"question":"In $\\ce{Fe2O3 + 2Al ->[\\Delta] Al2O3 + 2Fe}$, what happens to aluminum?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","q2","fb"]}}},"title":"New reactions"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Oxidation: gain of oxygen or loss of hydrogen. Reduction: loss of oxygen or gain of hydrogen.","The oxidizing agent supplies oxygen and is itself reduced.","The reducing agent (e.g. $H_2$, CO, C) takes oxygen away and is itself oxidized."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Key words"}},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"cuo","from":"cu1","label":"+ $\\ce{O2}$, heat: Cu oxidized"},{"to":"cu2","from":"cuo","label":"+ $\\ce{H2}$ (reducing agent), heat: CuO reduced"}],"nodes":[{"id":"cu1","label":"$\\ce{Cu}$ (pink)"},{"id":"cuo","label":"$\\ce{CuO}$ (black)"},{"id":"cu2","label":"$\\ce{Cu}$ (pink again)"}],"layout":"horizontal","caption":"The hook, step by step: oxidation, then reduction."},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the hook: the flame oxidized copper to CuO; hydrogen, the reducing agent, reduced it back."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","fd","hook","ex","self"]},"self":{"type":"Text","props":{"content":"Can you explain why CO is called a reducing agent, although it is oxidized?"},"children":[]}}},"title":"Summary"}],"title":"Oxidation and reduction by oxygen","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 economic importance p.6 (oxidizing agents $K_2Cr_2O_7$, $MnO_2$) and in the reduction of iron ores","subtitle":"Gain and loss of oxygen, and the agents that cause them","objectives":["Define oxidation as gain of oxygen (or loss of hydrogen) and reduction as loss of oxygen (or gain of hydrogen).","Identify the oxidizing agent and the reducing agent in a reaction.","Explain that the oxidizing agent is itself reduced, and the reducing agent is itself oxidized."],"concept_ids":["redox.basic"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Yes. The black solid is copper (II) oxide, and hydrogen removed its oxygen."},{"id":"b","feedback":"The copper came back pure, with no hydrogen in it, so hydrogen was not added to the copper."},{"id":"c","feedback":"The black layer is not soot. It formed when copper met the oxygen of the air in the flame."}],"explanation":"The black solid is copper (II) oxide, formed when copper gained oxygen from the air in the flame. Heating it in hydrogen took that oxygen away, so the copper came back."}},"s4":{"m":{"explanation":"Each agent is named for what it does to the other substance, not for what happens to it.","feedback_true":"That's the trap. The oxidizing agent oxidizes the other substance, so it is itself reduced. Here $CuO$ is the oxidizing agent: it gives its oxygen to $H_2$ and becomes Cu.","feedback_false":"Correct. The oxidizing agent oxidizes the other substance and is itself reduced: $CuO$ supplies oxygen and loses it."}},"s5":{"q":{"options":[{"id":"a","feedback":"Right. Magnesium takes the oxygen from $CO_2$, so it is the reducing agent, and it is itself oxidized."},{"id":"b","feedback":"$CO_2$ loses oxygen, so it is reduced. That makes it the oxidizing agent, not the reducing agent."},{"id":"c","feedback":"MgO is a product, not a reactant. The agents are reactants, on the left."},{"id":"d","feedback":"Carbon can be a reducing agent, but here it is a product, not a reactant."}],"explanation":"Mg takes the oxygen from $CO_2$ and becomes MgO, so Mg is oxidized and acts as the reducing agent. $CO_2$ loses oxygen, so it is reduced (the oxidizing agent); MgO and C are products."},"fb":{"mistakes":[{"id":"m1","feedback":"By the hydrogen part of the definitions, gaining hydrogen is reduction, and $H_2S$ loses hydrogen here."},{"id":"m2","feedback":"That names a role, but the blank asks for the process. Here $H_2S$ loses hydrogen and acts as the reducing agent."}],"explanation":"Loss of hydrogen is oxidation, so $H_2S$ is oxidized (and acts as the reducing agent)."},"q2":{"options":[{"id":"a","feedback":"Right. Al gains oxygen to become $Al_2O_3$; it took that oxygen from $Fe_2O_3$."},{"id":"b","feedback":"Al becomes $Al_2O_3$: it gains oxygen, and gaining oxygen is oxidation, not reduction."},{"id":"c","feedback":"That's the agent-name trap. The substance that is oxidized does the reducing, so aluminum is the reducing agent, not the oxidizing agent."}],"explanation":"Aluminum gains oxygen from $Fe_2O_3$ and becomes $Al_2O_3$, so it is oxidized. The substance that is oxidized does the reducing, so aluminum is the reducing agent."}},"s6":{"ex":{"body":"Key words: **oxidation**, **reduction**, **oxidizing agent**, **reducing agent**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"أيوه. الجسم الأسود ده هو الـ copper (II) oxide، والـ hydrogen شال منه الـ oxygen بتاعه."},{"id":"b","feedback":"الـ copper رجع نقي، ومفيهوش أي hydrogen، يعني الـ hydrogen ماتضافش للـ copper."},{"id":"c","feedback":"الطبقة السودا دي مش هباب. دي اتكوّنت لما الـ copper قابل الـ oxygen اللي في الهوا في اللهب."}],"explanation":"الجسم الأسود هو الـ copper (II) oxide، واتكوّن لما الـ copper كسب oxygen من الهوا في اللهب. ولما اتسخّن في الـ hydrogen، الـ hydrogen شال منه الـ oxygen ده، فالـ copper رجع."}},"s4":{"m":{"explanation":"كل agent اسمه جاي من اللي بيعمله في المادة التانية، مش من اللي بيحصل له هو.","feedback_true":"ده الفخ. الـ oxidizing agent بيعمل oxidation للمادة التانية، فهو نفسه بيبقى reduced. هنا الـ $CuO$ هو الـ oxidizing agent: بيدّي الـ oxygen بتاعه للـ $H_2$ ويرجع Cu.","feedback_false":"مظبوط. الـ oxidizing agent بيعمل oxidation للمادة التانية وهو نفسه بيبقى reduced: الـ $CuO$ بيدّي oxygen وبيخسره."}},"s5":{"q":{"options":[{"id":"a","feedback":"صح. الـ magnesium بياخد الـ oxygen من الـ $CO_2$، فهو الـ reducing agent، وهو نفسه بيبقى oxidized."},{"id":"b","feedback":"الـ $CO_2$ بيخسر oxygen، يبقى هو reduced، وده بيخليه الـ oxidizing agent، مش الـ reducing agent."},{"id":"c","feedback":"الـ MgO ده product، مش reactant. والـ agents هما الـ reactants اللي على الشمال."},{"id":"d","feedback":"الـ carbon ممكن يبقى reducing agent، لكن هنا هو product، مش reactant."}],"explanation":"الـ Mg بياخد الـ oxygen من الـ $CO_2$ ويبقى MgO، يعني الـ Mg بيبقى oxidized وهو الـ reducing agent. والـ $CO_2$ بيخسر oxygen، فهو reduced (الـ oxidizing agent)؛ أما الـ MgO والـ C فدول products."},"fb":{"mistakes":[{"id":"m1","feedback":"حسب جزء الـ hydrogen في التعريفات، كسب الـ hydrogen هو الـ reduction، والـ $H_2S$ هنا بيخسر hydrogen."},{"id":"m2","feedback":"ده اسم دور، لكن الفراغ محتاج اسم العملية. والـ $H_2S$ هنا بيخسر hydrogen وبيلعب دور الـ reducing agent."}],"explanation":"خسارة الـ hydrogen معناها oxidation، يبقى الـ $H_2S$ هو اللي oxidized (وهو هنا اللي بيلعب دور الـ reducing agent)."},"q2":{"options":[{"id":"a","feedback":"صح. الـ Al بيكسب oxygen ويبقى $Al_2O_3$، والـ oxygen ده خده من الـ $Fe_2O_3$."},{"id":"b","feedback":"الـ Al بيبقى $Al_2O_3$: يعني بيكسب oxygen، وكسب الـ oxygen ده oxidation مش reduction."},{"id":"c","feedback":"ده الفخ بتاع أسماء الـ agents. المادة اللي بيحصلها oxidation هي اللي بتعمل reduction للمادة التانية، يعني الـ aluminum هو الـ reducing agent مش الـ oxidizing agent."}],"explanation":"الـ aluminum بيكسب oxygen من الـ $Fe_2O_3$ ويبقى $Al_2O_3$، يعني بيبقى oxidized. والمادة اللي بيحصلها oxidation هي اللي بتعمل reduction للمادة التانية، فالـ aluminum هو الـ reducing agent."}},"s6":{"ex":{"body":"الكلمات اللي لازم تكتبها في الامتحان: **oxidation**، **reduction**، **oxidizing agent**، **reducing agent**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":10,"is_basics":true,"lesson_no":10,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":122,"end_s":170.4,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-redox.basic","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Oxidation and reduction by oxygen","duration_s":44.52,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":84,"page_to":84,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.uses-v-cr","kind":"lesson","version":3,"catalog_version":3,"ord":98,"primary_concept_id":"te.uses-v-cr","concepts":[{"concept_id":"te.uses-v-cr","role":"primary"}],"title":"Economic importance of vanadium and chromium","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A small portion added to the steel","correct":true},{"id":"b","text":"About half of the spring is vanadium","correct":false},{"id":"c","text":"The spring is made of pure vanadium","correct":false}],"question":"Predict: the steel of car springs contains vanadium. How much?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"A car spring is squeezed thousands of times on bumpy roads. Why doesn't it crack or rust away?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Springs that last"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"al","from":"st"},{"to":"sp","from":"al"}],"nodes":[{"id":"st","label":"Steel + a small portion of vanadium"},{"id":"al","label":"High hardness alloy that resists corrosion"},{"id":"sp","label":"Car springs"}],"caption":"Vanadium steel (book p.6)"},"children":[]},"gl":{"type":"Text","props":{"muted":true,"content":"An **alloy** is a metal mixed with other elements. You'll study alloys later."},"children":[]},"book":{"type":"Text","props":{"content":"When we add **a small portion of vanadium to steel**, an alloy of **high hardness** forms. It has a **great ability to resist corrosion**. So it is used in the manufacture of **car springs**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["recall","book","gl","fd"]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: corrosion slowly eats a metal away in air and moisture."},"children":[]}}},"title":"3- Vanadium in steel"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{V2O5}","caption":"Vanadium pentoxide: an important compound of vanadium"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"c1":{"type":"Card","props":{"tone":"warning","title":"Dyes"},"children":["c1t"]},"c2":{"type":"Card","props":{"tone":"brand","title":"Catalyst"},"children":["c2t"]},"c3":{"type":"Card","props":{"tone":"info","title":"Magnetic conductors"},"children":["c3t"]},"c1t":{"type":"Text","props":{"content":"In the manufacture of ceramics and the glass industry"},"children":[]},"c2t":{"type":"Text","props":{"content":"Speeds up a reaction without being used up"},"children":[]},"c3t":{"type":"Text","props":{"content":"In the manufacture of strong magnetic conductors"},"children":[]},"cols":{"type":"Columns","props":{"columns":3},"children":["c1","c2","c3"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","cols","m"]}}},"title":"Vanadium pentoxide (V₂O₅)"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MultiSelect","props":{"options":[{"id":"a","text":"Dyes in the manufacture of ceramics and glass","correct":true},{"id":"b","text":"A catalyst","correct":true},{"id":"c","text":"Manufacture of strong magnetic conductors","correct":true},{"id":"d","text":"Car springs","correct":false},{"id":"e","text":"Leather tanning","correct":false}],"question":"Which of these are uses of vanadium pentoxide ($\\ce{V2O5}$)? Choose all that apply."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q"]}}},"title":"Vanadium check"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"tab":{"type":"DataTable","props":{"rows":[["Chromium (Cr)","Metal plating; leather tanning"],["Chromium III oxide ($\\ce{Cr2O3}$)","Manufacture of dyes"],["Potassium dichromate ($\\ce{K2Cr2O7}$)","Oxidizing agent"]],"caption":"Chromium and its important compounds (book p.6)","headers":["Substance","Use"]},"children":[]},"book":{"type":"Text","props":{"content":"Chromium is a **chemically active metal**, but it resists the effect of atmospheric air. Chromium is used in **metal plating** and **leather tanning**."},"children":[]},"next":{"type":"Text","props":{"muted":true,"content":"Why does an active metal resist air? A later lesson explains it."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","tab","next"]}}},"title":"4- Chromium and its compounds"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Potassium dichromate, $\\ce{K2Cr2O7}$, is used as an **oxidizing agent**. It makes other substances undergo oxidation."},"children":[]},"cmp":{"type":"DataTable","props":{"rows":[["Oxidizing agent","oxidizes another substance and is itself reduced","$\\ce{K2Cr2O7}$"],["Reducing agent","takes oxygen away from another substance","$\\ce{H2}$, CO"]],"caption":"Oxidizing agent vs reducing agent","headers":["Agent","What it does","Example in this lesson"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["recall","t","cmp","m"]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: an **oxidizing agent** oxidizes another substance. It is itself reduced."},"children":[]}}},"title":"An oxidizing agent"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"spr","text":"Car springs (added to steel)"},{"id":"plt","text":"Metal plating"},{"id":"tan","text":"Leather tanning"},{"id":"cat","text":"A catalyst"},{"id":"mag","text":"Strong magnetic conductors"},{"id":"oxa","text":"An oxidizing agent"}],"answer":{"v":["spr","cat","mag"],"cr":["plt","tan","oxa"]},"prompt":"Sort each use by the element it comes from (the metal or one of its compounds).","categories":[{"id":"v","label":"Vanadium"},{"id":"cr","label":"Chromium"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It oxidizes another substance, and is itself reduced","correct":true},{"id":"b","text":"It takes oxygen away from another substance","correct":false},{"id":"c","text":"It speeds up the reaction and is not used up","correct":false},{"id":"d","text":"It colours the mixture as a dye","correct":false}],"question":"A lab adds potassium dichromate to a reaction mixture. What is its job?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Vanadium or chromium?"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["V in steel: high hardness alloy, resists corrosion: car springs.","$\\ce{V2O5}$: dyes in ceramics and glass, a catalyst, strong magnetic conductors.","Cr: metal plating and leather tanning. $\\ce{Cr2O3}$: dyes.","$\\ce{K2Cr2O7}$: an oxidizing agent."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"ans":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Check your answer"}},"children":["anst"]},"anst":{"type":"Text","props":{"content":"Besides dyes for ceramics and glass, $\\ce{V2O5}$ is an important **catalyst** (it speeds up a reaction and is not used up) and is used in the manufacture of **strong magnetic conductors**."},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the springs: a small portion of vanadium makes steel very hard and corrosion resistant."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["hook","b","ex","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why $\\ce{V2O5}$ is more than just a dye?"},"children":[]}}},"title":"Summary"}],"title":"Economic importance of vanadium and chromium","minutes":8,"book_ref":"Ch.1 economic importance: 3-Vanadium, 4-Chromium, p.6","subtitle":"Hard springs, a busy oxide and a strong oxidizing agent","objectives":["Explain why a small portion of vanadium is added to steel for car springs.","State the uses of vanadium pentoxide ($\\ce{V2O5}$): dyes in ceramics and glass, a catalyst, strong magnetic conductors.","State the uses of chromium (metal plating, leather tanning) and its compounds ($\\ce{Cr2O3}$ for dyes, $\\ce{K2Cr2O7}$ as an oxidizing agent)."],"concept_ids":["te.uses-v-cr"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good prediction. A little vanadium changes the whole steel. Let's see how."},{"id":"b","feedback":"That would be a lot of vanadium: a small portion of vanadium added to the steel is enough to give it high hardness."},{"id":"c","feedback":"Springs are steel, so iron is the main metal; vanadium is a small addition to that steel."}],"explanation":"A small portion of vanadium is added to the steel. It forms an alloy of high hardness that resists corrosion, so it is used to make car springs."}},"s3":{"m":{"statement":"$\\ce{V2O5}$ is just a dye.","correction":"$\\ce{V2O5}$ is also an important **catalyst**: it speeds up a reaction and is not used up. A dye stays in the glass as colour."}},"s4":{"q":{"options":[{"id":"a","feedback":"Yes, that is one of its three uses."},{"id":"b","feedback":"Yes. Many students miss this one, so well done."},{"id":"c","feedback":"Yes, that is the third use in the book."},{"id":"d","feedback":"Springs are a use of vanadium metal in steel, not of its oxide $\\ce{V2O5}$."},{"id":"e","feedback":"Leather tanning is a use of chromium, not of $\\ce{V2O5}$."}],"explanation":"$\\ce{V2O5}$ has three uses: dyes for ceramics and glass, a catalyst, and strong magnetic conductors."}},"s6":{"m":{"statement":"$\\ce{K2Cr2O7}$ is a reducing agent.","correction":"$\\ce{K2Cr2O7}$ oxidizes other substances, so it is an **oxidizing agent**. $\\ce{H2}$ and CO take oxygen away, so they are reducing agents."}},"s7":{"c":{"items":[{"id":"spr","feedback":"The car-spring use is the metal added in a small portion to steel, from step 2."},{"id":"plt","feedback":"Plating is in the table in step 5: the metal used to coat other metals."},{"id":"tan","feedback":"Leather tanning is in the table in step 5, with the same metal used for plating."},{"id":"cat","feedback":"The catalyst here is $\\ce{V2O5}$, the pentoxide from the cards in step 3."},{"id":"mag","feedback":"Strong magnetic conductors are one of the three uses of $\\ce{V2O5}$."},{"id":"oxa","feedback":"The oxidizing agent here is $\\ce{K2Cr2O7}$, the dichromate from step 6."}],"explanation":"Vanadium: car springs (in steel); $\\ce{V2O5}$ as a catalyst and in strong magnetic conductors. Chromium: plating and tanning; $\\ce{K2Cr2O7}$ as an oxidizing agent."},"q":{"options":[{"id":"a","feedback":"Right. That is what an oxidizing agent does."},{"id":"b","feedback":"That describes a reducing agent, like $\\ce{H2}$ or CO; the book gives $\\ce{K2Cr2O7}$ as an oxidizing agent."},{"id":"c","feedback":"That describes a catalyst, like $\\ce{V2O5}$; the book does not list $\\ce{K2Cr2O7}$ as a catalyst."},{"id":"d","feedback":"The dye compound of chromium is $\\ce{Cr2O3}$, not the dichromate."}],"explanation":"Potassium dichromate ($\\ce{K2Cr2O7}$) is used as an oxidizing agent: it oxidizes another substance and is itself reduced."}},"s8":{"ex":{"body":"Key words: **a small portion**, **high hardness**, **resist corrosion**, **catalyst**, **oxidizing agent**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"توقع حلو. شوية vanadium صغيرين بيغيّروا الـ steel كله. تعالى نشوف إزاي."},{"id":"b","feedback":"ده كده vanadium كتير أوي: جزء صغير من الـ vanadium بيتضاف للـ steel كفاية يدّيه صلادة عالية."},{"id":"c","feedback":"الـ springs معمولة من steel، يعني الـ iron هو الـ metal الأساسي، والـ vanadium مجرد إضافة صغيرة للـ steel ده."}],"explanation":"بيتضاف جزء صغير من الـ vanadium للـ steel. ده بيكوّن alloy صلادته عالية وبيقاوم الـ corrosion، عشان كده بيُستخدم في صناعة الـ car springs."}},"s3":{"m":{"statement":"الـ $\\ce{V2O5}$ مجرد dye وخلاص.","correction":"الـ $\\ce{V2O5}$ كمان **catalyst** مهم: بيسرّع التفاعل ومابيتستهلكش. إنما الـ dye بيفضل جوه الـ glass كلون."}},"s4":{"q":{"options":[{"id":"a","feedback":"أيوه، ده واحد من التلات استخدامات بتوعه."},{"id":"b","feedback":"أيوه. طلبة كتير بينسوا دي، فبرافو عليك."},{"id":"c","feedback":"أيوه، ده الاستخدام التالت في الكتاب."},{"id":"d","feedback":"الـ springs استخدام للـ vanadium الـ metal في الـ steel، مش للـ oxide بتاعه $\\ce{V2O5}$."},{"id":"e","feedback":"الـ leather tanning استخدام للـ chromium، مش للـ $\\ce{V2O5}$."}],"explanation":"الـ $\\ce{V2O5}$ ليه تلات استخدامات: dyes للـ ceramics والـ glass، و catalyst، و strong magnetic conductors."}},"s6":{"m":{"statement":"الـ $\\ce{K2Cr2O7}$ ده reducing agent.","correction":"الـ $\\ce{K2Cr2O7}$ بيأكسد المواد التانية، يبقى هو **oxidizing agent**. إنما الـ $\\ce{H2}$ والـ CO بياخدوا الأكسجين من المادة، فدول اللي reducing agents."}},"s7":{"c":{"items":[{"id":"spr","feedback":"الـ car springs معمولة من steel متضاف ليه جزء صغير من الـ vanadium."},{"id":"plt","feedback":"الـ metal plating استخدام للـ chromium الـ metal."},{"id":"tan","feedback":"الـ leather tanning استخدام للـ chromium الـ metal، زي الـ metal plating."},{"id":"cat","feedback":"الـ catalyst هنا هو الـ $\\ce{V2O5}$، الـ pentoxide بتاع الـ vanadium."},{"id":"mag","feedback":"الـ strong magnetic conductors واحد من التلات استخدامات بتوع الـ $\\ce{V2O5}$، الـ pentoxide بتاع الـ vanadium."},{"id":"oxa","feedback":"الـ oxidizing agent هنا هو الـ $\\ce{K2Cr2O7}$، الـ dichromate بتاع الـ chromium."}],"explanation":"الـ Vanadium: الـ car springs (في الـ steel)؛ والـ $\\ce{V2O5}$ كـ catalyst وفي الـ strong magnetic conductors. الـ Chromium: الـ plating والـ tanning؛ والـ $\\ce{K2Cr2O7}$ كـ oxidizing agent."},"q":{"options":[{"id":"a","feedback":"صح. ده بالظبط شغل الـ oxidizing agent."},{"id":"b","feedback":"ده وصف الـ reducing agent، زي الـ $\\ce{H2}$ أو الـ CO؛ إنما الكتاب بيذكر الـ $\\ce{K2Cr2O7}$ كـ oxidizing agent."},{"id":"c","feedback":"ده وصف الـ catalyst، زي الـ $\\ce{V2O5}$؛ والكتاب مش بيذكر الـ $\\ce{K2Cr2O7}$ كـ catalyst."},{"id":"d","feedback":"الـ compound بتاع الـ chromium اللي بيتستخدم في الـ dyes هو الـ $\\ce{Cr2O3}$، مش الـ dichromate."}],"explanation":"الـ potassium dichromate ($\\ce{K2Cr2O7}$) بيُستخدم كـ oxidizing agent: يعني بيأكسد مادة تانية وهو نفسه بيتختزل."}},"s8":{"ex":{"body":"الكلمات المهمة: **a small portion**، **high hardness**، **resist corrosion**، **catalyst**، **oxidizing agent**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":2,"lesson_no":15,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-uses","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Economic importance of the first transition series","duration_s":767.019,"start_s":113.3,"end_s":239.9,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.uses-v-cr","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Economic importance of vanadium and chromium","duration_s":50.39,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.activity-series","kind":"lesson","version":3,"catalog_version":3,"ord":100,"primary_concept_id":"chem.activity-series","concepts":[{"concept_id":"chem.activity-series","role":"primary"}],"title":"Chemical activity series of metals","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Magnesium is more chemically active than copper","correct":true},{"id":"b","text":"Copper is harder, so the acid cannot get in","correct":false},{"id":"c","text":"The acid is too weak for any metal","correct":false}],"question":"Predict: what is the difference between the two metals?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Drop magnesium ribbon into dilute hydrochloric acid and it fizzes. Drop in a copper wire and nothing happens. Why?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Fizz or nothing?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 360 300\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><text x=\"145\" y=\"24\" text-anchor=\"middle\" font-size=\"16\" fill=\"#e2e8f0\">K</text><text x=\"145\" y=\"48\" text-anchor=\"middle\" font-size=\"16\" fill=\"#e2e8f0\">Na</text><text x=\"145\" y=\"72\" text-anchor=\"middle\" font-size=\"16\" fill=\"#e2e8f0\">Ca</text><text x=\"145\" y=\"96\" text-anchor=\"middle\" font-size=\"16\" fill=\"#e2e8f0\">Mg</text><text x=\"145\" y=\"120\" text-anchor=\"middle\" font-size=\"16\" fill=\"#e2e8f0\">Al</text><text x=\"145\" y=\"144\" text-anchor=\"middle\" font-size=\"16\" fill=\"#e2e8f0\">Zn</text><text x=\"145\" y=\"168\" text-anchor=\"middle\" font-size=\"16\" fill=\"#e2e8f0\">Fe</text><line x1=\"90\" y1=\"187\" x2=\"200\" y2=\"187\" stroke=\"#fbbf24\" stroke-width=\"2\" stroke-dasharray=\"5 4\"/><text x=\"145\" y=\"192\" text-anchor=\"middle\" font-size=\"16\" font-weight=\"700\" fill=\"#fbbf24\">(H)</text><text x=\"145\" y=\"216\" text-anchor=\"middle\" font-size=\"16\" fill=\"#e2e8f0\">Cu</text><text x=\"145\" y=\"240\" text-anchor=\"middle\" font-size=\"16\" fill=\"#e2e8f0\">Ag</text><text x=\"145\" y=\"264\" text-anchor=\"middle\" font-size=\"16\" fill=\"#e2e8f0\">Au</text><line x1=\"60.0\" y1=\"270.0\" x2=\"60.0\" y2=\"20.0\" stroke=\"#94a3b8\" stroke-width=\"2\" stroke-linecap=\"round\"/><polygon points=\"60.0,20.0 63.9,28.1 56.1,28.1\" fill=\"#94a3b8\"/><text x=\"48\" y=\"150\" text-anchor=\"middle\" font-size=\"13\" fill=\"#94a3b8\" transform=\"rotate(-90 48 150)\">more active</text><line x1=\"215\" y1=\"12\" x2=\"215\" y2=\"166\" stroke=\"#34d399\" stroke-width=\"2\"/><text x=\"225\" y=\"84\" font-size=\"13\" fill=\"#34d399\">above hydrogen:</text><text x=\"225\" y=\"101\" font-size=\"13\" fill=\"#34d399\">displace hydrogen</text><text x=\"225\" y=\"118\" font-size=\"13\" fill=\"#34d399\">from dilute acids</text><line x1=\"215\" y1=\"204\" x2=\"215\" y2=\"286\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"225\" y=\"240\" font-size=\"13\" fill=\"#f87171\">below hydrogen:</text><text x=\"225\" y=\"257\" font-size=\"13\" fill=\"#f87171\">no reaction with</text><text x=\"225\" y=\"274\" font-size=\"13\" fill=\"#f87171\">dilute acids</text></svg>","caption":"Part of the chemical activity series","max_width":380},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Chemical activity series","definition":"The arrangement of metals in descending order according to their chemical activity."},"children":[]},"t":{"type":"Text","props":{"content":"Active means the metal reacts readily. It does not mean strong or hard."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","d","t"]}}},"title":"The activity series"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Metals **above hydrogen** displace hydrogen from dilute acids. Metals **below hydrogen** do not."},"children":[]},"f1":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Mg + 2HCl ->}\\\\ \\ce{MgCl2 + H2 ^}\\end{gathered}","caption":"Magnesium is above hydrogen: hydrogen gas bubbles out"},"children":[]},"f2":{"type":"Formula","props":{"latex":"\\ce{Cu + HCl -> \\text{no reaction}}","caption":"Copper is below hydrogen"},"children":[]},"t2":{"type":"Text","props":{"content":"The most active metals, like sodium and potassium, even displace hydrogen from cold water."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","f1","f2","t2"]}}},"title":"Above hydrogen"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"zn","text":"Zinc"},{"id":"fe","text":"Iron"},{"id":"ag","text":"Silver"},{"id":"au","text":"Gold"},{"id":"ca","text":"Calcium"}],"answer":{"no":["ag","au"],"yes":["zn","fe","ca"]},"prompt":"Each metal is dropped into dilute hydrochloric acid. Sort them.","categories":[{"id":"yes","label":"Hydrogen bubbles out"},{"id":"no","label":"No reaction"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"X is above hydrogen in the series; Y is below it","correct":true},{"id":"b","text":"Y is more active than X","correct":false},{"id":"c","text":"Both are below hydrogen","correct":false}],"question":"Metal X fizzes in dilute acid. Metal Y does not. Which statement fits?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Use the series"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["The activity series arranges metals in descending order of chemical activity.","Metals above hydrogen displace it from dilute acids; metals below it do not.","Active means reacts readily, not hard or strong."]},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Magnesium","above hydrogen","hydrogen bubbles out"],["Copper","below hydrogen","no reaction"]],"caption":"The hook's two metals in dilute hydrochloric acid","headers":["Metal","Place in the series","In dilute hydrochloric acid"]},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the hook: magnesium is above hydrogen and copper is below it."},"children":[]},"next":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","hook","tab","next","self"]},"self":{"type":"Text","props":{"content":"Can you explain why gold rings stay shiny, but iron nails rust?"},"children":[]}}},"title":"Summary"}],"title":"Chemical activity series of metals","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 4-Chromium, p.6 (chromium is a chemically active metal)","subtitle":"Some metals react eagerly, some hardly at all","objectives":["Describe the chemical activity series as metals arranged by how readily they react.","Use the series: metals above hydrogen displace it from dilute acids; metals below it do not.","Compare two metals' activity from their places in the series."],"concept_ids":["chem.activity-series"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. Metals differ in how readily they react."},{"id":"b","feedback":"Hardness is not what decides whether a metal reacts with the acid."},{"id":"c","feedback":"But magnesium did react in the same acid, so the acid is not too weak for every metal."}],"explanation":"Magnesium is more chemically active than copper. Magnesium is above hydrogen in the activity series and displaces it from dilute hydrochloric acid; copper is below hydrogen, so no reaction happens."}},"s4":{"c":{"items":[{"id":"zn","feedback":"Zinc is above the hydrogen line in the series, so it displaces hydrogen from the acid."},{"id":"fe","feedback":"Iron is above the hydrogen line in the series, so it displaces hydrogen from the acid."},{"id":"ag","feedback":"Silver is below the hydrogen line in the series, so it does not displace hydrogen from the acid."},{"id":"au","feedback":"Gold is below the hydrogen line in the series, so it does not displace hydrogen from the acid."},{"id":"ca","feedback":"Calcium is above the hydrogen line in the series, so it displaces hydrogen from the acid."}],"explanation":"Zn, Fe and Ca are above hydrogen, so they displace it. Ag and Au are below hydrogen."},"q":{"options":[{"id":"a","feedback":"Right. Only metals above hydrogen displace it from dilute acids."},{"id":"b","feedback":"The more active metal is the one that reacts, and X is the one that fizzed."},{"id":"c","feedback":"Then neither would displace hydrogen, but X fizzed, so it did displace it."}],"explanation":"X fizzes, so it displaces hydrogen from the dilute acid: X is above hydrogen in the series. Y does not react, so it is below hydrogen."}},"s5":{"next":{"body":"Chromium is a chemically active metal, yet it resists air. How?"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. الـ metals بتختلف في سهولة تفاعلها."},{"id":"b","feedback":"الصلابة مش هي اللي بتحدد إذا كان الـ acid هيتفاعل مع الـ metal ولا لأ."},{"id":"c","feedback":"الـ magnesium اتفاعل في نفس الـ acid، فالـ acid مش ضعيف على كل الـ metals."}],"explanation":"الـ magnesium أكتر active كيميائيًا من الـ copper. الـ magnesium فوق الـ hydrogen في الـ activity series وبيعمل displace ليه من الـ dilute hydrochloric acid، إنما الـ copper تحت الـ hydrogen فمفيش تفاعل."}},"s4":{"c":{"items":[{"id":"zn","feedback":"الـ zinc فوق خط الـ hydrogen في الـ series."},{"id":"fe","feedback":"الـ iron فوق خط الـ hydrogen في الـ series."},{"id":"ag","feedback":"الـ silver تحت خط الـ hydrogen في الـ series."},{"id":"au","feedback":"الـ gold تحت خط الـ hydrogen في الـ series."},{"id":"ca","feedback":"الـ calcium فوق خط الـ hydrogen في الـ series."}],"explanation":"الـ Zn والـ Fe والـ Ca فوق الـ hydrogen، فبيعملوا displace ليه. أما الـ Ag والـ Au فتحت الـ hydrogen."},"q":{"options":[{"id":"a","feedback":"صح. الـ metals اللي فوق الـ hydrogen تحديدًا هي اللي بتعمل displace ليه من الـ dilute acids."},{"id":"b","feedback":"الـ metal الأكتر active هو اللي بيتفاعل، والـ X هو اللي فوّر مش الـ Y."},{"id":"c","feedback":"لو الاتنين تحت الـ hydrogen، ولا واحد فيهم كان هيعمل displace ليه، لكن الـ X فوّر."}],"explanation":"الـ X بيفوّر، يعني بيعمل displace للـ hydrogen من الـ dilute acid: يبقى فوق الـ hydrogen في الـ series. والـ Y مابيتفاعلش، يبقى تحت الـ hydrogen."}},"s5":{"next":{"body":"الـ chromium ده active metal كيميائيًا، ومع كده بيقاوم الهوا. إزاي؟"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":11,"is_basics":true,"lesson_no":11,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":243.9,"end_s":276.4,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.activity-series","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Chemical activity series of metals","duration_s":47.08,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.chromium-oxide-layer","kind":"lesson","version":3,"catalog_version":3,"ord":102,"primary_concept_id":"te.chromium-oxide-layer","concepts":[{"concept_id":"te.chromium-oxide-layer","role":"primary"}],"title":"Why chromium resists the effect of atmosphere","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A layer forms on its surface and protects it","correct":true},{"id":"b","text":"Chromium is an unreactive metal, like gold","correct":false},{"id":"c","text":"Chromium does not meet oxygen in air","correct":false}],"question":"Predict: why doesn't chromium keep reacting with air?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Chromium is a chemically active metal. 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Right: rust lets air and moisture in.","max_width":380},"children":[]},"m":{"type":"TrueFalse","props":{"answer":false,"statement":"Any oxide layer protects a metal."},"children":[]},"t":{"type":"Text","props":{"content":"This is why chromium is useful in metal plating."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","m","t"]}}},"title":"Not every oxide protects"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A non-porous oxide layer forms on its surface and blocks oxygen","correct":true},{"id":"b","text":"Aluminum is less active than iron","correct":false},{"id":"c","text":"Any oxide on a metal stops further corrosion","correct":false}],"question":"Aluminum is above iron in the activity series. Yet aluminum window frames do not corrode away. Which is the best explanation?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Chromium resists the effect of air because it is an inactive metal."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tf","q"]}}},"title":"Give the reason"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"o":{"type":"Ordering","props":{"items":[{"id":"a","text":"Chromium, an active metal, reacts with oxygen of air"},{"id":"b","text":"A metal oxide forms on its surface"},{"id":"c","text":"The oxide's molecular volume is larger than that of the metal atoms"},{"id":"d","text":"A non-porous layer covers the surface"},{"id":"e","text":"Oxygen of air cannot continue reacting with the metal"}],"prompt":"Put the steps of the explanation in order."},"children":[]},"fb":{"type":"FillBlank","props":{"text":"The molecular volume of the oxide is ___ than that of the metal atoms, so it forms a ___ layer.","answers":[["larger","bigger","greater"],["nonporous","non-porous","non porous"]],"mistakes":[{"id":"m1","blank":0,"answer":"smaller"},{"id":"m2","blank":1,"answer":"porous"},{"id":"m3","blank":1,"answer":"thin"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o","fb"]}}},"title":"Build the chain"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Chromium is a chemically active metal.","Its oxide's molecular volume is larger than that of the metal atoms: a non-porous layer forms.","Rust on iron is porous, so it does not protect the iron."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"tbl":{"type":"DataTable","props":{"rows":[["Chemically active metal","yes","yes"],["Layer on the surface","metal oxide","rust"],["Kind of layer","non-porous","porous"],["Oxygen of air","cannot continue reacting with the metal","keeps reaching the metal"]],"caption":"Two active metals, two oxide layers","headers":["","Chromium","Iron"],"highlight":[{"col":1,"row":2},{"col":2,"row":2}]},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the taps: chromium reacts, but its oxide seals it."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["hook","b","tbl","ex","self"]},"self":{"type":"Text","props":{"content":"Can you explain why rust does not protect iron, but chromium oxide protects chromium?"},"children":[]}}},"title":"Summary"}],"title":"Why chromium resists the effect of atmosphere","minutes":8,"book_ref":"Ch.1 4-Chromium, p.6; Evaluation Q7.2, p.27","subtitle":"Active metal, protected surface","objectives":["Give reasons: chromium is chemically active, yet it resists the effect of atmospheric air.","Explain that the oxide's molecular volume is larger than that of the metal atoms, so it forms a non-porous layer.","Contrast the non-porous chromium oxide layer with porous rust on iron."],"concept_ids":["te.chromium-oxide-layer"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good prediction. Let's see what this layer is and why it works."},{"id":"b","feedback":"Chromium is not unreactive like gold: the book calls it a chemically active metal, so something else must protect it."},{"id":"c","feedback":"Air touches every surface, so oxygen does reach chromium at first."}],"explanation":"Chromium is chemically active, so it does react with oxygen of air. The oxide that forms makes a non-porous layer on the surface, and this layer prevents the continued interaction with oxygen."}},"s4":{"m":{"explanation":"Protection depends on the kind of layer: a non-porous layer, like chromium's oxide, keeps oxygen out; a porous layer, like rust, lets air and moisture through.","feedback_true":"Not every oxide layer protects. Chromium's oxide forms a non-porous layer that blocks oxygen. Rust on iron is porous: air and moisture pass through it, so rusting continues.","feedback_false":"Right. Only a non-porous layer, like chromium's oxide, protects the metal. Porous rust lets air and moisture reach the iron."}},"s5":{"q":{"options":[{"id":"a","feedback":"Yes. Same idea as chromium: an active metal protected by a non-porous oxide."},{"id":"b","feedback":"This contradicts the question: aluminum sits above iron in the activity series, so it is the more active of the two."},{"id":"c","feedback":"Not every oxide stops corrosion: rust on iron is porous, so air and moisture pass through it and corrosion continues."}],"explanation":"Aluminum is more active than iron, yet its window frames do not corrode away. As with chromium, an active metal is protected when its oxide forms a non-porous layer that blocks oxygen."},"tf":{"explanation":"Book p.6: chromium is chemically active, but the molecular volume of its oxide is larger than that of the metal atoms, so the oxide forms a non-porous layer that prevents the continued interaction with oxygen of air.","feedback_true":"Chromium is not inactive: the book calls it a chemically active metal. It resists air because a non-porous oxide layer forms on its surface.","feedback_false":"Right. Chromium is active; its non-porous oxide layer protects it."}},"s6":{"o":{"items":[{"id":"a","feedback":"The reaction with oxygen comes first: no oxide can exist before chromium reacts."},{"id":"b","feedback":"The oxide forms as a result of that reaction, so it comes right after it."},{"id":"c","feedback":"The larger molecular volume describes the oxide, so it comes after the oxide forms."},{"id":"d","feedback":"The layer is non-porous because of the larger molecular volume, so it comes after that fact."},{"id":"e","feedback":"Stopping the reaction with oxygen is the final result of the non-porous layer."}],"explanation":"React → oxide forms → larger molecular volume → non-porous layer → no continued reaction with oxygen."},"fb":{"mistakes":[{"id":"m1","feedback":"A smaller oxide could not close every gap between the atoms, so the layer would not seal the surface."},{"id":"m2","feedback":"A porous layer has holes that let air through, so it would not stop oxygen."},{"id":"m3","feedback":"Thickness is not the book's word here: what matters is that air cannot pass through the layer."}],"explanation":"Larger molecular volume → a continuous, non-porous layer."}},"s7":{"ex":{"body":"Give reasons: Cr resists air although it is active. Key words: **molecular volume of the oxide is larger than that of the metal atoms**. **Non-porous layer**. **Prevents continued interaction with oxygen**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"توقّع حلو. تعالى نشوف الطبقة دي إيه وبتشتغل إزاي."},{"id":"b","feedback":"الـ chromium مش خامل زي الـ gold: الكتاب بيقول إنه metal نشيط كيميائيًا، يبقى فيه حاجة تانية هي اللي بتحميه."},{"id":"c","feedback":"الهوا بيلمس أي سطح، فالـ oxygen بيوصل للـ chromium فعلًا في الأول."}],"explanation":"الـ chromium نشيط كيميائيًا، فهو فعلًا بيتفاعل مع الـ oxygen اللي في الهوا. الـ oxide اللي بيتكوّن بيعمل طبقة non-porous على السطح، والطبقة دي بتمنع إن التفاعل مع الـ oxygen يكمّل."}},"s4":{"m":{"explanation":"الحماية بتعتمد على نوع الطبقة: الطبقة الـ non-porous، زي الـ oxide بتاع الـ chromium، بتمنع الـ oxygen؛ والطبقة الـ porous، زي الـ rust، بتسيب الهوا والرطوبة يعدّوا.","feedback_true":"مش أي طبقة oxide بتحمي. الـ oxide بتاع الـ chromium بيعمل طبقة non-porous بتمنع الـ oxygen. أما الـ rust على الـ iron فهو porous: الهوا والرطوبة بيعدّوا منه، فالصدأ بيكمّل.","feedback_false":"صح. الطبقة الـ non-porous تحديدًا، زي الـ oxide بتاع الـ chromium، هي اللي بتحمي الـ metal. الـ rust الـ porous بيسيب الهوا والرطوبة يوصلوا للـ iron."}},"s5":{"q":{"options":[{"id":"a","feedback":"أيوه. نفس فكرة الـ chromium: metal نشيط بيحميه oxide طبقته non-porous."},{"id":"b","feedback":"ده عكس اللي في السؤال: الـ aluminum فوق الـ iron في الـ activity series، يعني هو الأنشط فيهم."},{"id":"c","feedback":"مش أي oxide بيوقّف التآكل: الـ rust على الـ iron طبقته porous، فالهوا والرطوبة بيعدّوا منه والتآكل بيكمّل."}],"explanation":"الـ aluminum أنشط من الـ iron، ومع ذلك الشبابيك اللي معمولة منه مابتتآكلش. زي الـ chromium بالظبط: الـ metal النشيط بيتحمي لما الـ oxide بتاعه يعمل طبقة non-porous تمنع الـ oxygen."},"tf":{"explanation":"الكتاب صفحة 6: الـ chromium نشيط كيميائيًا، لكن الـ molecular volume بتاع الـ oxide بتاعه أكبر من الـ metal atoms، فالـ oxide بيعمل طبقة non-porous بتمنع إن التفاعل مع الـ oxygen اللي في الهوا يكمّل.","feedback_true":"الـ chromium مش خامل: الكتاب بيقول إنه metal نشيط كيميائيًا. هو بيقاوم الهوا عشان طبقة oxide non-porous بتتكوّن على سطحه.","feedback_false":"صح. الـ chromium نشيط؛ وطبقة الـ oxide الـ non-porous بتاعته هي اللي بتحميه."}},"s6":{"o":{"items":[{"id":"a","feedback":"التفاعل مع الـ oxygen بييجي الأول: مفيش oxide يقدر يتكوّن قبل ما الـ chromium يتفاعل."},{"id":"b","feedback":"الـ oxide بيتكوّن نتيجة التفاعل ده، فبييجي بعده على طول."},{"id":"c","feedback":"الـ molecular volume الأكبر ده وصف للـ oxide، فبييجي بعد ما الـ oxide يتكوّن."},{"id":"d","feedback":"الطبقة non-porous بسبب الـ molecular volume الأكبر، فبتيجي بعد المعلومة دي."},{"id":"e","feedback":"وقف التفاعل مع الـ oxygen هو النتيجة الأخيرة للطبقة الـ non-porous."}],"explanation":"تفاعل → الـ oxide بيتكوّن → الـ molecular volume أكبر → طبقة non-porous → مفيش تفاعل تاني مع الـ oxygen."},"fb":{"mistakes":[{"id":"m1","feedback":"oxide أصغر مش هيقدر يقفل كل الفراغات اللي بين الذرات، فالطبقة مش هتقفل السطح."},{"id":"m2","feedback":"الطبقة الـ porous فيها مسام بتعدّي الهوا، فمش هتمنع الـ oxygen."},{"id":"m3","feedback":"السُمك مش هو كلمة الكتاب هنا: المهم إن الهوا مايقدرش يعدّي من الطبقة."}],"explanation":"الـ molecular volume أكبر → طبقة متصلة non-porous."}},"s7":{"ex":{"body":"علّل: الـ Cr بيقاوم الهوا رغم إنه نشيط. الكلمات المفتاحية: **molecular volume of the oxide is larger than that of the metal atoms** (حجم الـ oxide أكبر من حجم ذرات الـ metal)، و**non-porous layer**، و**prevents continued interaction with oxygen** (بتمنع إن التفاعل مع الـ oxygen يكمّل)."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":3,"lesson_no":16,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-uses","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Economic importance of the first transition series","duration_s":767.019,"start_s":263.9,"end_s":323.1,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.chromium-oxide-layer","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Why chromium resists the effect of atmosphere","duration_s":50.45,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"2","relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.uses-mn","kind":"lesson","version":2,"catalog_version":3,"ord":104,"primary_concept_id":"te.uses-mn","concepts":[{"concept_id":"te.uses-mn","role":"primary"}],"title":"Economic importance of manganese","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It is brittle","correct":true},{"id":"b","text":"It is too soft","correct":false},{"id":"c","text":"It is too rare to use","correct":false}],"question":"Predict: what is wrong with pure manganese?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Train rails and soft-drink cans both contain manganese. Yet nobody makes anything from pure manganese. Why not?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Rails and cans"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Brittle metal","definition":"A metal that breaks easily when it is hit or bent."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"al","from":"mn"},{"to":"cp","from":"mn"}],"nodes":[{"id":"mn","label":"Manganese (brittle)"},{"id":"al","label":"Alloys"},{"id":"cp","label":"Compounds"}],"caption":"How manganese is used"},"children":[]},"gl":{"type":"Text","props":{"muted":true,"content":"An **alloy** is a metal mixed with other elements. You'll study alloys later."},"children":[]},"book":{"type":"Text","props":{"content":"Manganese is **not used as a pure metal** because it is a **brittle metal**. So it is always used as **alloys or compounds**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","book","gl","fd"]}}},"title":"Never used pure"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Each alloy has a use and a reason. Learn them as pairs."},"children":[]},"rv":{"type":"Reveal","props":{"label":"Show the second alloy"},"children":["tab2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","tab1","rv"]},"tab1":{"type":"DataTable","props":{"rows":[["Ferromanganese","Railway track","it is harder than steel"]],"caption":"Alloy 1 (book p.6)","headers":["Alloy","Use","Because"]},"children":[]},"tab2":{"type":"DataTable","props":{"rows":[["Aluminum-manganese alloy","Soft drinks vessels (cans)","it resists corrosion"]],"caption":"Alloy 2 (book p.6)","headers":["Alloy","Use","Because"]},"children":[]}}},"title":"Two alloys"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Ferromanganese alloy","correct":true},{"id":"b","text":"Pure manganese","correct":false},{"id":"c","text":"Aluminum-manganese alloy","correct":false}],"question":"Engineers need a material for a new railway track. It must be harder than steel. What fits the book?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Aluminum-manganese alloys are used for soft drinks cans because they are harder than steel."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Pick the alloy"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Antiseptic","definition":"A substance that kills germs, for example on a wound."},"children":[]},"c1":{"type":"Card","props":{"tone":"brand","title":"$\\ce{MnO2}$"},"children":["c1t"]},"c2":{"type":"Card","props":{"tone":"info","title":"$\\ce{KMnO4}$"},"children":["c2t"]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"dc","from":"mno2","label":"strong oxidizing agent"},{"to":"an","from":"kmno4","label":"kills germs"}],"nodes":[{"id":"mno2","label":"$\\ce{MnO2}$"},{"id":"dc","label":"Dry cell"},{"id":"kmno4","label":"$\\ce{KMnO4}$"},{"id":"an","label":"Antiseptic"}],"caption":"Two manganese compounds and their uses"},"children":[]},"c1t":{"type":"Text","props":{"content":"Manganese dioxide: a strong oxidizing agent used in the dry cell"},"children":[]},"c2t":{"type":"Text","props":{"content":"Potassium permanganate: an antiseptic substance"},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["cols","recall","k","fd"]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: an oxidizing agent oxidizes another substance."},"children":[]}}},"title":"Dry cell and antiseptic"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Fungicide","definition":"A substance that kills fungi."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"c3":{"type":"Card","props":{"tone":"success","title":"$\\ce{MnSO4}$"},"children":["c3t"]},"c3t":{"type":"Text","props":{"content":"Manganese II sulphate: used as a fungicide"},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["$\\ce{KMnO4}$","germs","antiseptic"],["$\\ce{MnSO4}$","fungi","fungicide"]],"caption":"Do not swap them","headers":["Compound","Kills","Use"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c3","k","m","tab"]}}},"title":"A fungicide"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"rail","text":"Railway track"},{"id":"cans","text":"Soft drinks cans"},{"id":"hard","text":"Harder than steel"},{"id":"anti","text":"Antiseptic substance"},{"id":"fung","text":"Fungicide"}],"answer":{"fm":["rail","hard"],"almn":["cans"],"kmno4":["anti"],"mnso4":["fung"]},"prompt":"Sort each use or reason under its alloy or compound.","categories":[{"id":"fm","label":"Ferromanganese"},{"id":"almn","label":"Al-Mn alloy"},{"id":"kmno4","label":"$\\ce{KMnO4}$"},{"id":"mnso4","label":"$\\ce{MnSO4}$"}]},"children":[]},"fb":{"type":"FillBlank","props":{"text":"In the dry cell, $\\ce{MnO2}$ acts as a strong ___ agent.","answers":[["oxidizing","oxidising"]],"mistakes":[{"id":"m1","blank":0,"answer":"reducing"},{"id":"m2","blank":0,"answer":"catalyst"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","fb"]}}},"title":"Match manganese uses"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Mn is brittle, so it is used as alloys or compounds, not as a pure metal.","Ferromanganese: railway track. Al-Mn alloy: soft drinks cans.","$\\ce{MnO2}$: strong oxidizing agent in the dry cell.","$\\ce{KMnO4}$: antiseptic. $\\ce{MnSO4}$: fungicide."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"It is used as alloys and compounds: ferromanganese in railway track (harder than steel), Al-Mn alloy in soft drinks cans (resists corrosion), $\\ce{MnO2}$ in the dry cell, $\\ce{KMnO4}$ as an antiseptic and $\\ce{MnSO4}$ as a fungicide."},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the hook: pure manganese is brittle, so rails and cans use its alloys."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["hook","b","ex","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why manganese is useful, although the pure metal is brittle?"},"children":[]}}},"title":"Summary"}],"title":"Economic importance of manganese","minutes":8,"book_ref":"Ch.1 economic importance: 5-Manganese, p.6","subtitle":"Brittle alone, useful in alloys and compounds","objectives":["Explain why manganese is not used as a pure metal.","Give the uses of ferromanganese (railway track) and aluminum-manganese alloys (soft drinks cans), with the reasons.","State the uses of $\\ce{MnO2}$ (dry cell), $\\ce{KMnO4}$ (antiseptic) and $\\ce{MnSO4}$ (fungicide)."],"concept_ids":["te.uses-mn"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good prediction. A brittle metal breaks instead of bending."},{"id":"b","feedback":"Soft metals bend and dent; pure manganese has a different weakness."},{"id":"c","feedback":"Rarity is not the problem here; the problem is how the pure metal behaves when it is hit."}],"explanation":"Pure manganese is brittle, so it is not used as a pure metal; it is used in alloys or compounds."}},"s4":{"q":{"options":[{"id":"a","feedback":"Right. Ferromanganese is harder than steel, so it is used in railway track."},{"id":"b","feedback":"Pure manganese is brittle, so a track of it would crack."},{"id":"c","feedback":"That alloy is chosen because it resists corrosion, for cans, not because it is harder than steel."}],"explanation":"Ferromanganese alloy fits: the book says it is used in railway track because it is harder than steel."},"tf":{"explanation":"Aluminum-manganese alloys are used for soft drinks cans because they resist corrosion. Being harder than steel is the reason ferromanganese is used in railway track.","feedback_true":"Aluminum-manganese alloys are used for cans because they resist corrosion; being harder than steel is the reason another alloy is used.","feedback_false":"Right. The cans need an alloy that resists corrosion."}},"s6":{"m":{"statement":"$\\ce{MnSO4}$ is the antiseptic and $\\ce{KMnO4}$ is the fungicide.","correction":"It is the other way round. Permanganate, $\\ce{KMnO4}$, is the antiseptic (germs); sulphate, $\\ce{MnSO4}$, is the fungicide (fungi)."}},"s7":{"c":{"items":[{"id":"rail","feedback":"Railway track needs the alloy that is harder than steel (step 3)."},{"id":"cans","feedback":"Soft drinks cans need the alloy that resists corrosion (step 3)."},{"id":"hard","feedback":"This is a reason: being harder than steel belongs with the alloy used in railway track."},{"id":"anti","feedback":"Antiseptic and fungicide are easy to swap: the antiseptic is the compound that kills germs on wounds (step 5)."},{"id":"fung","feedback":"Antiseptic and fungicide are easy to swap: the fungicide is the compound that kills fungi (step 6)."}],"explanation":"Ferromanganese: railway track, harder than steel. Al-Mn: cans. $\\ce{KMnO4}$: antiseptic. $\\ce{MnSO4}$: fungicide."},"fb":{"mistakes":[{"id":"m1","feedback":"A reducing agent takes oxygen away, and $\\ce{MnO2}$ does the opposite to other substances (step 5)."},{"id":"m2","feedback":"Catalyst is not an agent type; the book uses a different agent word for $\\ce{MnO2}$ in the dry cell."}],"explanation":"$\\ce{MnO2}$ is a strong oxidizing agent used in the dry cell."}},"s8":{"ex":{"body":"Give reasons: Mn is not used pure → **it is a brittle metal**. Ferromanganese in rails → **harder than steel**. Al-Mn cans → **resists corrosion**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"توقّع حلو. الـ metal الهش (brittle) بيتكسر بدل ما ينثني."},{"id":"b","feedback":"الـ metals الطرية بتنثني وبتتبعج، لكن الـ manganese النقي نقطة ضعفه تانية: لما يتخبط مابينثنيش."},{"id":"c","feedback":"الندرة مش هي المشكلة هنا: المشكلة في الـ metal النقي نفسه لما يتخبط."}],"explanation":"الـ manganese النقي هش (brittle)، عشان كده مش بيُستخدم كـ metal نقي، وبيُستخدم في alloys أو compounds."}},"s4":{"q":{"options":[{"id":"a","feedback":"صح. الـ ferromanganese أصلد من الـ steel، عشان كده بيُستخدم في قضبان السكة الحديد."},{"id":"b","feedback":"الـ manganese النقي هش (brittle)، فقضبان معمولة منه هتتشرخ، وعشان كده الـ manganese بيُستخدم في alloys."},{"id":"c","feedback":"الـ alloy ده بيتختار عشان بيقاوم الـ corrosion، وده للعلب، مش عشان أصلد من الـ steel."}],"explanation":"الـ ferromanganese alloy هو اللي ينفع: الكتاب بيقول إنه بيُستخدم في قضبان السكة الحديد عشان أصلد من الـ steel."},"tf":{"explanation":"الـ aluminum-manganese alloys بتُستخدم في علب الـ soft drinks عشان بتقاوم الـ corrosion. أما إنه أصلد من الـ steel فده سبب استخدام الـ ferromanganese في قضبان السكة الحديد.","feedback_true":"الـ aluminum-manganese alloys بتُستخدم في العلب عشان بتقاوم الـ corrosion، أما الـ alloy اللي أصلد من الـ steel فهو الـ ferromanganese.","feedback_false":"صح. العلب محتاجة alloy بيقاوم الـ corrosion."}},"s6":{"m":{"statement":"الـ $\\ce{MnSO4}$ هو الـ antiseptic، والـ $\\ce{KMnO4}$ هو الـ fungicide.","correction":"العكس هو الصح. الـ permanganate، $\\ce{KMnO4}$، هو الـ antiseptic (للجراثيم)؛ والـ sulphate، $\\ce{MnSO4}$، هو الـ fungicide (للفطريات)."}},"s7":{"c":{"items":[{"id":"rail","feedback":"قضبان السكة الحديد محتاجة alloy أصلد من الـ steel."},{"id":"cans","feedback":"العلب محتاجة alloy بيقاوم الـ corrosion."},{"id":"hard","feedback":"ده سبب، مش استخدام: هو السبب إن الـ alloy ده بيُستخدم في قضبان السكة الحديد."},{"id":"anti","feedback":"الـ antiseptic بيقتل الجراثيم على الجروح، ومش هو نفس الـ compound اللي بيقتل الفطريات."},{"id":"fung","feedback":"الـ fungicide بيقتل الفطريات، ومش هو نفس الـ compound اللي بيتحط على الجروح كـ antiseptic."}],"explanation":"الـ Ferromanganese: قضبان السكة الحديد، لأنه أصلد من الـ steel. الـ Al-Mn: العلب. الـ $\\ce{KMnO4}$: antiseptic. الـ $\\ce{MnSO4}$: fungicide."},"fb":{"mistakes":[{"id":"m1","feedback":"الـ reducing agent بيشيل الـ oxygen، والـ $\\ce{MnO2}$ في الـ dry cell بيعمل عكس كده."},{"id":"m2","feedback":"الـ catalyst مش نوع من أنواع الـ agent، والـ $\\ce{MnO2}$ في الـ dry cell بيشتغل كـ agent قوي، مش مجرد مسرّع للتفاعل."}],"explanation":"الـ $\\ce{MnO2}$ هو strong oxidizing agent بيُستخدم في الـ dry cell."}},"s8":{"ex":{"body":"Give reasons: الـ Mn مش بيُستخدم نقي ← **it is a brittle metal**. الـ ferromanganese في قضبان السكة الحديد ← **harder than steel**. علب الـ Al-Mn ← **resists corrosion**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":4,"lesson_no":17,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-uses","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Economic importance of the first transition series","duration_s":767.019,"start_s":329.7,"end_s":379.7,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.uses-mn","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Economic importance of manganese","duration_s":44.4,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-atom.isotopes","kind":"lesson","version":3,"catalog_version":3,"ord":106,"primary_concept_id":"atom.isotopes","concepts":[{"concept_id":"atom.isotopes","role":"primary"}],"title":"Isotopes and average atomic mass","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It is an average of chlorine atoms with different masses","correct":true},{"id":"b","text":"Each chlorine atom has 18.5 neutrons","correct":false},{"id":"c","text":"It is a rounding mistake in the table","correct":false}],"question":"Predict: where does the .5 come from?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"The periodic table gives chlorine an atomic mass of 35.5. Can an atom hold half a neutron?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Half a neutron?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Isotopes","definition":"Atoms of the same element with the same atomic number but different mass numbers, due to different numbers of neutrons."},"children":[]},"t":{"type":"Text","props":{"content":"Same protons, so same element. Different neutrons, so different masses."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Chlorine-35",17,18,35],["Chlorine-37",17,20,37]],"caption":"Two isotopes of chlorine","headers":["Isotope","Protons","Neutrons","Mass number"],"highlight":[{"col":2,"row":0},{"col":2,"row":1}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","tab","t"]}}},"title":"Isotopes"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"p":50},"elements":{"t":{"type":"Text","props":{"content":"Natural chlorine is a mix of both isotopes. Change the share of chlorine-35. Find the table's value."},"children":[]},"ok":{"type":"Callout","props":{"variant":"tip"},"visible":{"eq":75,"$state":"/p"},"children":[]},"sl":{"type":"Slider","props":{"max":100,"min":0,"step":5,"unit":"%","label":"Chlorine-35 in the mix","value":{"$bindState":"/p"}},"children":[]},"st":{"type":"Stat","props":{"tone":"brand","label":"Average atomic mass","value":{"args":{"p":{"$state":"/p"},"expr":"(35 * p + 37 * (100 - p)) / 100","digits":2},"$computed":"calc"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","st","ok"]}}},"title":"Mix the isotopes"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\text{atomic mass} = \\frac{(35 \\times 75) + (37 \\times 25)}{100}\\\\ = 35.5\\end{gathered}"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"The more common isotope pulls the average towards its own mass."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","m","t"]}}},"title":"An average, not one atom"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"10.8","correct":true},{"id":"b","text":"10.5","correct":false},{"id":"c","text":"11","correct":false},{"id":"d","text":"10.2","correct":false}],"question":"Boron has two isotopes: boron-10 (20%) and boron-11 (80%). Its atomic mass is closest to:"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"In the nucleus, isotopes of one element have the same number of ___ but different numbers of ___.","answers":[["protons"],["neutrons"]],"mistakes":[{"id":"m1","blank":0,"answer":"neutrons"},{"id":"m2","blank":0,"answer":"electrons"},{"id":"m3","blank":1,"answer":"protons"},{"id":"m4","blank":1,"answer":"electrons"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","fb"]}}},"title":"A new element"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Isotopes: same atomic number, different mass numbers, due to different numbers of neutrons.","The atomic mass in the table is the average of the isotopes, weighted by how common each is.","Chlorine: 75% Cl-35 + 25% Cl-37 → 35.5, so no atom needs half a neutron."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_t"]},"next":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","next","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why the atomic mass of boron is not a whole number?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"Boron is a mix of two isotopes: boron-10 (20%) and boron-11 (80%). Its atomic mass is their weighted average: $0.20 \\times 10 + 0.80 \\times 11 = 10.8$. Boron-11 is much more common, so the average is close to 11."},"children":[]}}},"title":"Summary"}],"title":"Isotopes and average atomic mass","minutes":5,"book_ref":"Prerequisite (G10 chemistry); used in Ch.1 p.7 (radioactive isotopes of cobalt) and p.12 (nickel: average mass of five stable isotopes)","subtitle":"Same element, different neutrons","objectives":["Define isotopes: same atomic number, different mass numbers (different numbers of neutrons).","Explain that the atomic mass in the table is the average of the isotopes, weighted by how common each is.","Estimate an element's atomic mass from two isotopes and their percentages."],"concept_ids":["atom.isotopes"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. Not all chlorine atoms have the same mass."},{"id":"b","feedback":"Neutrons are whole particles, so a single atom cannot have half of one."},{"id":"c","feedback":"The table is not wrong: the .5 is a real value, not a rounding mistake."}],"explanation":"Chlorine atoms do not all have the same mass: chlorine has isotopes. The 35.5 in the table is the average mass of its atoms, not the mass of one atom."}},"s3":{"ok":{"body":"75% chlorine-35 and 25% chlorine-37 give 35.5, the value in the table.","title":"Found it"}},"s4":{"m":{"statement":"The atomic mass in the table is the mass number of one atom.","correction":"No chlorine atom has a mass of 35.5. It is the **average** of the isotopes, weighted by how common each one is."}},"s5":{"q":{"options":[{"id":"a","feedback":"Right. Boron-11 is far more common, so the average sits close to 11."},{"id":"b","feedback":"That is the plain middle of 10 and 11, but the isotopes are not equally common, so the average does not sit in the middle."},{"id":"c","feedback":"That is the mass number of one boron-11 atom, but the table gives an average, and boron-10 counts in it too."},{"id":"d","feedback":"This pulls towards boron-10, but boron-10 is the less common isotope here (20%)."}],"explanation":"The atomic mass is an average weighted by how common each isotope is: 0.20 × 10 + 0.80 × 11 = 2 + 8.8 = 10.8. Boron-11 is far more common, so the average lies close to 11."},"fb":{"mistakes":[{"id":"m1","feedback":"Same element means same atomic number, and the atomic number does not count that particle."},{"id":"m2","feedback":"Electrons are outside the nucleus, and this blank needs the nucleus particle that fixes which element it is."},{"id":"m3","feedback":"If that number changed, it would no longer be the same element; the particle that differs is another one in the nucleus."},{"id":"m4","feedback":"Electrons are outside the nucleus and add nothing to the mass number, so they are not the nucleus particle that differs."}],"explanation":"Same protons (same atomic number), different neutrons (different mass numbers)."}},"s6":{"next":{"body":"In Chapter 1: cobalt's radioactive isotopes, and nickel's average atomic mass."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. مش كل ذرات الـ chlorine ليها نفس الكتلة."},{"id":"b","feedback":"الـ neutrons جسيمات كاملة، فالذرة الواحدة متقدرش يبقى فيها نص neutron."},{"id":"c","feedback":"الجدول مش غلطان: الـ .5 دي ليها سبب حقيقي، مش غلطة تقريب."}],"explanation":"ذرات الـ chlorine مش كلها ليها نفس الكتلة: الـ chlorine ليه isotopes. والـ 35.5 اللي في الجدول هو متوسط كتلة ذراته، مش كتلة ذرة واحدة."}},"s3":{"ok":{"body":"75% chlorine-35 مع 25% chlorine-37 بيدّوا 35.5، وهي نفس القيمة اللي في الجدول.","title":"لقيتها"}},"s4":{"m":{"statement":"الـ atomic mass اللي في الجدول هو الـ mass number بتاع ذرة واحدة.","correction":"مفيش ولا ذرة chlorine كتلتها 35.5. الرقم ده **متوسط** الـ isotopes، وكل isotope بيتحسب على قد ما هو منتشر."}},"s5":{"q":{"options":[{"id":"a","feedback":"صح. الـ boron-11 منتشر أكتر بكتير، فالمتوسط بييجي قريب من 11."},{"id":"b","feedback":"ده النص بالظبط بين 10 و 11، لكن الـ isotopes مش منتشرين بنفس النسبة."},{"id":"c","feedback":"ده الـ mass number لذرة boron-11 واحدة، والجدول بيدّي متوسط بيحسب الـ boron-10 كمان."},{"id":"d","feedback":"كده المتوسط مايل ناحية الـ boron-10، مع إن الـ boron-11 هو المنتشر أكتر (80%)."}],"explanation":"الـ atomic mass متوسط بيتحسب حسب نسبة انتشار كل isotope: 0.20 × 10 + 0.80 × 11 = 2 + 8.8 = 10.8. والـ boron-11 منتشر أكتر بكتير، فالمتوسط بييجي قريب من 11."},"fb":{"mistakes":[{"id":"m1","feedback":"نفس العنصر يعني نفس الـ atomic number، والـ atomic number مش بيعدّ الـ neutrons."},{"id":"m2","feedback":"الـ electrons برّه الـ nucleus، والمطلوب هنا جسيم جوه الـ nucleus هو اللي بيحدد العنصر."},{"id":"m3","feedback":"لو العدد ده اتغيّر، العنصر نفسه هيتغيّر، فالـ isotopes مش بتختلف فيه."},{"id":"m4","feedback":"الـ electrons برّه الـ nucleus ومش بيزوّدوا حاجة في الـ mass number، والمطلوب هنا جسيم جوه الـ nucleus."}],"explanation":"نفس الـ protons (يعني نفس الـ atomic number)، و neutrons مختلفة (يعني mass numbers مختلفة)."}},"s6":{"next":{"body":"في الفصل الأول: الـ radioactive isotopes بتاعة الـ cobalt، والـ average atomic mass بتاع الـ nickel."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":12,"is_basics":true,"lesson_no":12,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":59.4,"end_s":108,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-atom.isotopes","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Isotopes and average atomic mass","duration_s":43.69,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 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The food does not become radioactive: only the source contains the radioactive isotope."},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the hook: gamma rays can reach a tumour because of their high penetrating power."},"children":[]},"next":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","hook","next","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why food treated with gamma rays is safe to eat?"},"children":[]}}},"title":"Summary"}],"title":"Radioactivity and gamma rays","minutes":5,"book_ref":"Prerequisite (G10 physics/chemistry); used in Ch.1 7-Cobalt, p.7 (cobalt 60 produces gamma rays)","subtitle":"Unstable nuclei and very penetrating rays","objectives":["Describe a radioactive isotope as one with an unstable nucleus that gives out radiation.","Describe gamma rays as high-energy electromagnetic rays with high penetrating power.","Explain that an object exposed to gamma rays does not become radioactive."],"concept_ids":["phys.radioactivity-gamma"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Yes. It needs high penetrating power. Let's meet such rays."},{"id":"b","feedback":"Visible light stops at the skin, so it could not reach a tumour inside."},{"id":"c","feedback":"Being attracted by a magnet does not help a ray reach a tumour deep inside."}],"explanation":"To reach a tumour deep inside the body, the ray must pass through skin and flesh: it needs high penetrating power, as gamma rays have."}},"s4":{"m":{"statement":"Anything exposed to gamma rays becomes radioactive.","correction":"Gamma rays used to treat food or tools pass through and are gone, so the object does not become radioactive. Only the source contains the radioactive isotope."}},"s5":{"q":{"options":[{"id":"a","feedback":"Right. The rays passed through and killed the germs. The gloves do not give out rays."},{"id":"b","feedback":"That is the common worry, but the gloves take in no radioactive isotope."},{"id":"c","feedback":"Gamma rays are not stored: they pass through or are absorbed, so a pack cannot hold them."}],"explanation":"The gamma rays pass through the sealed pack and kill the germs. The gloves take in no radioactive isotope and the rays are not stored, so the gloves give out no radiation afterwards."},"fb":{"mistakes":[{"id":"m1","feedback":"Stable nuclei do not break down, and this isotope's nucleus does."},{"id":"m2","feedback":"That describes its nucleus; the blank needs the name of the isotope itself."}],"explanation":"It is a radioactive isotope."},"tf":{"explanation":"Gamma rays have high penetrating power: they pass through paper, the body and thin metal. That is why they can kill germs inside a sealed pack.","feedback_true":"Right. They pass through paper, the body and thin metal.","feedback_false":"The gamma rays passed through paper, the body and even thin metal."}},"s6":{"next":{"body":"In Chapter 1: what the gamma rays of cobalt 60 are used for."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"أيوه. لازم يبقى ليه high penetrating power. يلا نتعرف على أشعة زي دي."},{"id":"b","feedback":"الضوء المرئي بيقف عند الجلد، فمش هيوصل لورم جوه الجسم."},{"id":"c","feedback":"المغناطيس مش هو الموضوع هنا: اللي يهم إن الشعاع يوصل لورم في عمق الجسم."}],"explanation":"عشان الشعاع يوصل لورم في عمق الجسم، لازم يعدّي من الجلد واللحم: يعني يكون ليه high penetrating power، زي الـ gamma rays."}},"s4":{"m":{"statement":"أي حاجة تتعرض للـ gamma rays بتبقى radioactive.","correction":"الـ gamma rays اللي بنعالج بيها الأكل أو الأدوات بتعدّي منها وتمشي، فالحاجة مش بتبقى radioactive. الـ radioactive isotope موجود في المصدر لوحده."}},"s5":{"q":{"options":[{"id":"a","feedback":"صح. الأشعة عدّت من خلالهم وقتلت الجراثيم، والجوانتيات مش بتطلّع أي أشعة."},{"id":"b","feedback":"دي الحاجة اللي ناس كتير بتقلق منها، لكن مفيش radioactive isotope دخل جوه الجوانتيات."},{"id":"c","feedback":"الـ gamma rays مش بتتخزن: يا إما بتعدّي يا إما بتتمتص، فمفيش علبة تقدر تحبسها جواها."}],"explanation":"الـ gamma rays بتعدّي من العلبة المقفولة وبتقتل الجراثيم. مفيش radioactive isotope بيدخل الجوانتيات والأشعة مش بتتخزن، فالجوانتيات مش بتطلّع أي radiation بعد كده."},"fb":{"mistakes":[{"id":"m1","feedback":"الـ nuclei الـ stable مش بتتحلل، والـ isotope هنا الـ nucleus بتاعته بتتحلل وبتطلّع radiation."},{"id":"m2","feedback":"دي صفة الـ nucleus بتاعته، والمطلوب اسم الـ isotope نفسه."}],"explanation":"اسمه radioactive isotope."},"tf":{"explanation":"الـ gamma rays ليها high penetrating power: بتعدّي من الورق والجسم ولوح الـ metal الرفيع. وعشان كده تقدر تقتل الجراثيم جوه علبة مقفولة.","feedback_true":"صح. بتعدّي من الورق والجسم ولوح الـ metal الرفيع.","feedback_false":"الـ gamma rays عدّت من مواد زي الورق والجسم ولوح الـ metal الرفيع."}},"s6":{"next":{"body":"في الفصل الأول: الـ gamma rays بتاعة الـ cobalt 60 بنستخدمها في إيه."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":13,"is_basics":true,"lesson_no":13,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-uses","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Economic importance of the first transition series","duration_s":767.019,"start_s":479.6,"end_s":533,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-phys.radioactivity-gamma","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Radioactivity and gamma rays","duration_s":52.77,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-te.uses-fe-co","kind":"lesson","version":5,"catalog_version":3,"ord":110,"primary_concept_id":"te.uses-fe-co","concepts":[{"concept_id":"te.uses-fe-co","role":"primary"}],"title":"Economic importance of iron and cobalt","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It produces gamma rays with high penetrating power","correct":true},{"id":"b","text":"It can be magnetized","correct":false},{"id":"c","text":"It is a very hard metal","correct":false}],"question":"Predict: why is cobalt 60 useful in treating tumours?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Iron holds up the power lines outside. A cobalt isotope helps doctors treat tumours. How?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Iron and cobalt"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Look around: the steel rods inside concrete buildings are iron."},"children":[]},"book":{"type":"Text","props":{"content":"Iron is used in the manufacture of:"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","uses","t"]},"uses":{"type":"DataTable","props":{"rows":[["Reinforced concrete"],["Electricity pylons"],["Knives"],["Gun and cannon barrels"],["Surgical tools"]],"caption":"Uses of iron (book p.6)","headers":["Iron is used in the manufacture of"]},"children":[]}}},"title":"6- Iron in everyday life"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{N2 + 3H2 ->[Fe] 2NH3}","caption":"Iron (Fe) over the arrow is the catalyst; conditions: 500 °C, 200 atm"},"children":[]},"t":{"type":"Text","props":{"content":"Iron is used as a **catalyst** in the manufacture of **ammonia** by the **Haber-Bosch method**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["recall","t","f"]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: a catalyst speeds up a reaction without being used up."},"children":[]}}},"title":"Iron as a catalyst: Haber-Bosch"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Water gas","definition":"A mixture of hydrogen and carbon monoxide."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"fuel","from":"wg","label":"Fischer-Tropsch method, Fe catalyst"}],"nodes":[{"id":"wg","label":"Water gas ($\\ce{H2}$ + CO)"},{"id":"fuel","label":"Fuel"}],"caption":"Iron also catalyses the conversion of water gas to a fuel"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","fd"]}}},"title":"Iron as a catalyst: Fischer-Tropsch"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A fuel, by the Fischer-Tropsch method","correct":true},{"id":"b","text":"Ammonia, by the Haber-Bosch method","correct":false},{"id":"c","text":"Water vapour","correct":false}],"question":"A factory passes a mixture of $\\ce{H2}$ and CO over an iron catalyst. What does it make?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Water gas is water in the gas state."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Iron check"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Cobalt is also used in the manufacture of **modern dry batteries** used in cars."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"mz","from":"fe"},{"to":"mz","from":"co"},{"to":"mg","from":"mz","label":"so"}],"nodes":[{"id":"fe","label":"Iron"},{"id":"co","label":"Cobalt"},{"id":"mz","label":"Can be magnetized"},{"id":"mg","label":"Magnets"}],"caption":"Cobalt is similar to iron: both can be magnetized (book p.7)"},"children":[]},"book":{"type":"Text","props":{"content":"Cobalt is similar to iron: both of them **can be magnetized**. So they are used in the manufacture of **magnets**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","fd","t"]}}},"title":"7- Cobalt: magnets and batteries"},{"id":"s7","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"TrueFalse","props":{"answer":false,"statement":"Cobalt 60 is used in treating tumours because cobalt can be magnetized."},"children":[]},"book":{"type":"Text","props":{"content":"Cobalt has **twelve radioactive isotopes**. Cobalt 60 is very important because it produces **gamma rays** with **high penetrating power**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","uses","m"]},"uses":{"type":"DataTable","props":{"rows":[["Food preserving"],["Detecting the quality of industrial products"],["Detecting cracks and welding connections"],["Medicine: diagnosis and treatment of tumours"]],"caption":"Uses of cobalt 60 (book p.7)","headers":["Gamma rays of cobalt 60 are used in"]},"children":[]}}},"title":"Cobalt 60 and gamma rays"},{"id":"s8","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"pyl","text":"Electricity pylons"},{"id":"hab","text":"Catalyst in making ammonia"},{"id":"bat","text":"Modern dry batteries used in cars"},{"id":"crk","text":"Detecting cracks and welding connections"},{"id":"sur","text":"Surgical tools"},{"id":"fuel","text":"Converting water gas to a fuel"}],"answer":{"co":["bat","crk"],"fe":["pyl","hab","sur","fuel"]},"prompt":"Sort each use by the element.","categories":[{"id":"fe","label":"Iron"},{"id":"co","label":"Cobalt"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"No. The rays pass through; the food does not become radioactive","correct":true},{"id":"b","text":"Yes, but only for a few days","correct":false},{"id":"c","text":"No, because cobalt is magnetic","correct":false}],"question":"Mangoes are treated with gamma rays from cobalt 60 to preserve them. A buyer asks: \"Are they radioactive now?\" The best reply is:"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Iron or cobalt?"},{"id":"s9","kind":"recap","spec":{"root":"root","elements":{"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Used in the manufacture of","reinforced concrete, electricity pylons, knives, gun and cannon barrels, surgical tools","magnets (like iron), modern dry batteries used in cars"],["Special use","catalyst: ammonia (Haber-Bosch method); water gas ($\\ce{H2}$ + CO) to a fuel (Fischer-Tropsch method)","cobalt 60: gamma rays with high penetrating power (food preserving, quality of industrial products, cracks and welding connections, tumours)"]],"caption":"Economic importance of iron and cobalt (book pp.6-7)","headers":["","Iron (Fe)","Cobalt (Co)"]},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the hook: cobalt 60 treats tumours because its gamma rays have high penetrating power."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["hook","tab","ex","self"]},"self":{"type":"Text","props":{"content":"Can you explain why gamma-treated food is not radioactive?"},"children":[]}}},"title":"Summary"}],"title":"Economic importance of iron and cobalt","minutes":9,"book_ref":"Ch.1 economic importance: 6-Iron, 7-Cobalt, pp.6-7","subtitle":"From pylons to gamma rays","objectives":["State the uses of iron, including as a catalyst in the Haber-Bosch and Fischer-Tropsch methods.","Describe water gas as a mixture of hydrogen and carbon monoxide.","State the uses of cobalt and explain why cobalt 60 is used: it produces gamma rays with high penetrating power."],"concept_ids":["te.uses-fe-co"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Right: cobalt 60 produces gamma rays with high penetrating power, and these are used in treating tumours."},{"id":"b","feedback":"Cobalt can be magnetized, but that is not what reaches a tumour: what reaches it is the radiation from the radioactive isotope."},{"id":"c","feedback":"Hardness doesn't help inside the body; what reaches the tumour is the radiation from the radioactive isotope."}],"explanation":"Cobalt 60 is a radioactive isotope of cobalt that produces gamma rays with high penetrating power. That radiation is what reaches the tumour, so cobalt 60 is used in the diagnosis and treatment of tumours."}},"s5":{"q":{"options":[{"id":"a","feedback":"Right. $\\ce{H2}$ + CO is water gas, and iron helps convert it to a fuel."},{"id":"b","feedback":"Haber-Bosch starts from $\\ce{N2}$ and $\\ce{H2}$, and this mixture has no nitrogen."},{"id":"c","feedback":"That mixes up water gas with water vapour. $\\ce{H2}$ + CO is water gas, and it is turned into a fuel."}],"explanation":"A mixture of $\\ce{H2}$ and CO is water gas. With iron as the catalyst it is converted to a fuel by the Fischer-Tropsch method; the Haber-Bosch method makes ammonia from $\\ce{N2}$ and $\\ce{H2}$."},"tf":{"explanation":"Water vapour is $\\ce{H2O}$ as a gas. Water gas is a mixture of hydrogen and carbon monoxide ($\\ce{H2}$ + CO), and iron catalyses its conversion to a fuel (Fischer-Tropsch method).","feedback_true":"That's the name trap. As the definition card in step 4 says, water gas is a mixture of hydrogen and carbon monoxide, not water in the gas state.","feedback_false":"Right. Water gas is a mixture of hydrogen and carbon monoxide."}},"s7":{"m":{"explanation":"Cobalt 60 is used in treating tumours because it produces gamma rays with high penetrating power; cobalt being magnetizable is the reason it is used in magnets.","feedback_true":"That mixes up two uses. Cobalt's ability to be magnetized is why it is used in magnets. Cobalt 60 is used for another reason: it produces gamma rays with high penetrating power.","feedback_false":"Right. Cobalt 60 is used because it produces gamma rays with high penetrating power, not because cobalt can be magnetized."}},"s8":{"c":{"items":[{"id":"pyl","feedback":"Electricity pylons are a use of iron (step 2)."},{"id":"hab","feedback":"Iron is the catalyst written over the arrow in the Haber-Bosch method."},{"id":"bat","feedback":"Cobalt is used in modern dry batteries used in cars (step 6)."},{"id":"crk","feedback":"Detecting cracks uses the gamma rays of cobalt 60, a radioactive isotope of cobalt (step 7)."},{"id":"sur","feedback":"Surgical tools are in the list of iron's uses (step 2)."},{"id":"fuel","feedback":"Iron is the catalyst of the Fischer-Tropsch method."}],"explanation":"Iron: pylons, surgical tools, catalyst (Haber-Bosch, Fischer-Tropsch). Cobalt: car dry batteries; cobalt 60 for cracks and welds."},"q":{"options":[{"id":"a","feedback":"Right. The radioactive isotope stays in the source, not in the fruit."},{"id":"b","feedback":"That is the common worry, but no cobalt 60 gets inside the mangoes: the rays pass through the fruit."},{"id":"c","feedback":"Magnetism has nothing to do with it: the gamma rays pass through the fruit, and no cobalt 60 gets inside it, so the mangoes do not become radioactive."}],"explanation":"The gamma rays from cobalt 60 pass through the mangoes. The radioactive isotope stays in the source and does not get into the fruit, so the mangoes do not become radioactive."}},"s9":{"ex":{"body":"Give reasons: cobalt 60 is used in food preserving → **it produces gamma rays which have high penetrating power**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"صح: الـ cobalt 60 بيطلّع gamma rays ليها high penetrating power، ودي بتتستخدم في علاج الأورام."},{"id":"b","feedback":"الـ cobalt فعلًا بيتمغنط، لكن ده مش اللي بيوصل للورم؛ اللي بيوصل هو الإشعاع اللي بيطلّعه الـ radioactive isotope."},{"id":"c","feedback":"الصلابة مش هتفيد جوه الجسم؛ اللي بيوصل للورم هو الإشعاع اللي بيطلّعه الـ radioactive isotope."}],"explanation":"الـ cobalt 60 ده radioactive isotope من الـ cobalt بيطلّع gamma rays ليها high penetrating power. الإشعاع ده هو اللي بيوصل للورم، وعشان كده الـ cobalt 60 بيتستخدم في تشخيص وعلاج الأورام."}},"s5":{"q":{"options":[{"id":"a","feedback":"صح. الـ $\\ce{H2}$ + CO ده هو الـ water gas، والـ iron بيساعد إنه يتحوّل لـ fuel."},{"id":"b","feedback":"الـ Haber-Bosch بيبدأ من الـ $\\ce{N2}$ والـ $\\ce{H2}$، والخليط ده مفيهوش nitrogen."},{"id":"c","feedback":"كده إنت خلطت بين الـ water gas وبخار المية. الـ $\\ce{H2}$ + CO ده الـ water gas، وبيتحوّل لـ fuel."}],"explanation":"خليط الـ $\\ce{H2}$ والـ CO ده هو الـ water gas. والـ iron هو الـ catalyst اللي بيحوّله لـ fuel بطريقة الـ Fischer-Tropsch؛ إنما الـ Haber-Bosch فبيعمل ammonia من الـ $\\ce{N2}$ والـ $\\ce{H2}$."},"tf":{"explanation":"بخار المية هو $\\ce{H2O}$ في الحالة الغازية. إنما الـ water gas خليط من الـ hydrogen والـ carbon monoxide ($\\ce{H2}$ + CO)، والـ iron هو الـ catalyst اللي بيحوّله لـ fuel (طريقة الـ Fischer-Tropsch).","feedback_true":"ده فخ الاسم. زي ما بطاقة المصطلح في الخطوة 4 بتقول، الـ water gas خليط من الـ hydrogen والـ carbon monoxide، مش مية في الحالة الغازية.","feedback_false":"صح. الـ water gas خليط من الـ hydrogen والـ carbon monoxide."}},"s7":{"m":{"explanation":"الـ cobalt 60 بيتستخدم في علاج الأورام عشان بيطلّع gamma rays ليها high penetrating power؛ إنما إن الـ cobalt بيتمغنط فده سبب استخدامه في الـ magnets.","feedback_true":"كده إنت خلطت بين استخدامين. إن الـ cobalt بيتمغنط ده سبب استخدامه في الـ magnets. إنما الـ cobalt 60 بيتستخدم لسبب تاني: بيطلّع gamma rays ليها high penetrating power.","feedback_false":"صح. الـ cobalt 60 بيتستخدم عشان بيطلّع gamma rays ليها high penetrating power، مش عشان الـ cobalt بيتمغنط."}},"s8":{"c":{"items":[{"id":"pyl","feedback":"الـ pylons من استخدامات الـ iron (الخطوة 2)."},{"id":"hab","feedback":"الـ iron هو الـ catalyst المكتوب فوق السهم في طريقة الـ Haber-Bosch."},{"id":"bat","feedback":"الـ cobalt بيدخل في الـ modern dry batteries بتاعة العربيات (الخطوة 6)."},{"id":"crk","feedback":"اكتشاف الـ cracks بيستخدم الـ gamma rays بتاعة الـ cobalt 60، وده radioactive isotope من الـ cobalt (الخطوة 7)."},{"id":"sur","feedback":"الـ surgical tools من قايمة استخدامات الـ iron (الخطوة 2)."},{"id":"fuel","feedback":"الـ iron هو الـ catalyst في طريقة الـ Fischer-Tropsch."}],"explanation":"الـ iron: الـ pylons، والـ surgical tools، والـ catalyst (في الـ Haber-Bosch والـ Fischer-Tropsch). الـ cobalt: الـ dry batteries بتاعة العربيات؛ والـ cobalt 60 لاكتشاف الـ cracks والـ welds."},"q":{"options":[{"id":"a","feedback":"صح. الـ radioactive isotope بيفضل في المصدر، مش في الفاكهة."},{"id":"b","feedback":"ده القلق اللي بيتكرر، لكن مفيش cobalt 60 بيدخل جوه المانجا: الأشعة بتعدّي من الفاكهة."},{"id":"c","feedback":"المغناطيسية ملهاش دعوة هنا: الـ gamma rays بتعدّي من الفاكهة، ومفيش cobalt 60 بيدخل جواها، فالمانجا مابتبقاش radioactive."}],"explanation":"الـ gamma rays اللي بتطلع من الـ cobalt 60 بتعدّي من المانجا. الـ radioactive isotope بيفضل في المصدر ومش بيدخل الفاكهة، فالمانجا مابتبقاش radioactive."}},"s9":{"ex":{"body":"علّل: الـ cobalt 60 بيتستخدم في حفظ الأغذية ← **عشان بيطلّع gamma rays ليها high penetrating power**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":5,"lesson_no":18,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-uses","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Economic importance of the first transition series","duration_s":767.019,"start_s":387,"end_s":538.6,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.uses-fe-co","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Economic importance of iron and cobalt","duration_s":48.63,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.uses-ni","kind":"lesson","version":4,"catalog_version":3,"ord":112,"primary_concept_id":"te.uses-ni","concepts":[{"concept_id":"te.uses-ni","role":"primary"}],"title":"Economic importance of nickel","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Corrosion at high temperature","correct":true},{"id":"b","text":"Nothing: it only needs to conduct electricity well","correct":false},{"id":"c","text":"Magnets near the coil","correct":false}],"question":"Predict: what must a heating coil resist?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"A hair dryer coil glows red hot every day, yet it lasts for years. What does it need?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"The red-hot coil"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"gl":{"type":"Text","props":{"muted":true,"content":"An **alloy** is a metal mixed with other elements. You'll study alloys later."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Nickel-cadmium battery","can be recharged"],["Nickel-steel alloys","hard; resist rust and the effect of acids"],["Nickel plating","protects other metals from oxidation and rust; gives them a beautiful appearance"]],"caption":"Nickel uses (book p.7)","headers":["Use","What the book says"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tab","recall","gl"]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: rusting is the corrosion of iron in moist air."},"children":[]}}},"title":"8- Nickel: batteries, alloys, plating"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"TrueFalse","props":{"answer":false,"statement":"The book's reason for using nickel-chromium alloys in heating coils is that they conduct electricity well."},"children":[]},"book":{"type":"Text","props":{"content":"Nickel-chromium alloys are used in **heating coils** and **electric furnaces** because they **resist corrosion at high temperature**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","m"]}}},"title":"Heating coils"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"They resist corrosion at high temperature","correct":true},{"id":"b","text":"They are good conductors of electricity","correct":false},{"id":"c","text":"They can be recharged","correct":false}],"question":"A bakery oven has heating coils that glow red hot for hours every day. Why use a nickel-chromium alloy for them?"},"children":[]},"q2":{"type":"MCQ","props":{"options":[{"id":"a","text":"Nickel plating","correct":true},{"id":"b","text":"A nickel-cadmium battery","correct":false},{"id":"c","text":"Finely divided nickel","correct":false}],"question":"A company wants steel bicycle handlebars that don't rust and look shiny. Which nickel use fits best?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","q2"]}}},"title":"Nickel check"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{array}{c}\\text{oil} + \\ce{H2}\\\\ \\downarrow\\ \\text{finely divided Ni}\\\\ \\text{hydrogenated oil}\\end{array}"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Hydrogenation of oils","definition":"Adding hydrogen to liquid oils, for example to make solid ghee."},"children":[]},"book":{"type":"Text","props":{"content":"**Finely divided nickel** is used as a **catalyst** in the **hydrogenation of oils**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["recall","book","k","f"]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: a catalyst speeds up a reaction without being used up."},"children":[]}}},"title":"Finely divided nickel"},{"id":"s6","kind":"interact","spec":{"root":"root","state":{"n":1},"elements":{"m":{"type":"TrueFalse","props":{"answer":false,"statement":"A lump of nickel works as well as the same mass of finely divided nickel."},"children":[]},"t":{"type":"Text","props":{"content":"Cut a 1 cm cube of nickel into smaller cubes. The mass stays the same. Watch the surface."},"children":[]},"s1":{"type":"Stat","props":{"tone":"neutral","label":"Small cubes","value":{"args":{"n":{"$state":"/n"},"expr":"n ^ 3","digits":0},"$computed":"calc"}},"children":[]},"s2":{"type":"Stat","props":{"tone":"brand","unit":"cm²","label":"Total surface area","value":{"args":{"n":{"$state":"/n"},"expr":"6 * n","digits":0},"$computed":"calc"}},"children":[]},"sl":{"type":"Slider","props":{"max":6,"min":1,"step":1,"label":"Pieces along each edge","value":{"$bindState":"/n"}},"children":[]},"row":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["s1","s2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","row","m"]}}},"title":"Why a fine powder?"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"hot","text":"Resists corrosion at high temperature"},{"id":"look","text":"Gives metals a beautiful appearance"},{"id":"surf","text":"Has a very large surface area"},{"id":"rust","text":"Protects other metals from oxidation and rust"}],"answer":{"coil":["hot"],"plate":["look","rust"],"powder":["surf"]},"prompt":"Sort each reason under the nickel use it explains.","categories":[{"id":"coil","label":"Ni-Cr heating coils"},{"id":"plate","label":"Nickel plating"},{"id":"powder","label":"Finely divided Ni catalyst"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The finely divided nickel gives faster hydrogenation","correct":true},{"id":"b","text":"Both work at the same rate, because the mass is the same","correct":false},{"id":"c","text":"The lumps work faster, because they are heavier pieces","correct":false}],"question":"Two flasks hold oil and hydrogen. One gets 5 g of nickel lumps; the other gets 5 g of finely divided nickel. What happens?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Match the reason"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Nickel-cadmium battery","can be recharged"],["Nickel-steel alloys","hard; resist rust and the effect of acids"],["Nickel-chromium alloys: heating coils, electric furnaces","resist corrosion at high temperature"],["Nickel plating","protects other metals from oxidation and rust; gives them a beautiful appearance"],["Finely divided nickel","catalyst in the hydrogenation of oils"]],"caption":"Economic importance of nickel (book p.7)","headers":["Nickel use","What the book says"]},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the coil: nickel-chromium alloys resist corrosion at high temperature."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["hook","tab","ex","self"]},"self":{"type":"Text","props":{"content":"Can you explain why the nickel catalyst is used as a fine powder?"},"children":[]}}},"title":"Summary"}],"title":"Economic importance of nickel","minutes":8,"book_ref":"Ch.1 economic importance: 8-Nickel, p.7","subtitle":"Batteries, hot coils and a powder catalyst","objectives":["State the uses of nickel: nickel-cadmium batteries, nickel-steel alloys and nickel plating.","Explain why nickel-chromium alloys are used in heating coils and electric furnaces.","Explain why finely divided nickel is used as a catalyst in the hydrogenation of oils."],"concept_ids":["te.uses-ni"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Right: a hot coil meets air all day, so it must resist corrosion at high temperature."},{"id":"b","feedback":"Conducting is needed, but a hot coil also meets air all day, and hot metal reacts faster with air."},{"id":"c","feedback":"Magnets are not the problem in a hair dryer; the hot metal meets air, which corrodes it."}],"explanation":"A heating coil is hot and meets air all day, and hot metal reacts faster with air, so the coil must resist corrosion at high temperature. That is why nickel-chromium alloys are used in heating coils."}},"s3":{"m":{"explanation":"The book says nickel-chromium alloys are used in heating coils and electric furnaces because they resist corrosion at high temperature, not because of how well they conduct.","feedback_true":"Not the book's reason. A hot coil meets air all day, so the book says nickel-chromium alloys are used because they resist corrosion at high temperature. Copper conducts better, yet it is not used for heating coils.","feedback_false":"Right. The book's reason is that nickel-chromium alloys resist corrosion at high temperature."}},"s4":{"q":{"options":[{"id":"a","feedback":"Right. That is the book's reason for heating coils and electric furnaces."},{"id":"b","feedback":"That is the common trap: conducting well is not the book's reason for using this alloy in heating coils."},{"id":"c","feedback":"Recharging is about the nickel-cadmium battery, not about heating coils."}],"explanation":"Coils that glow red hot for hours need a material that resists corrosion at high temperature; that is the book's reason for using nickel-chromium alloys in heating coils. Recharging belongs to the nickel-cadmium battery."},"q2":{"options":[{"id":"a","feedback":"Right. Plating protects from oxidation and rust and gives a beautiful appearance."},{"id":"b","feedback":"A battery stores energy; it does not protect the handlebar's surface or make it shiny."},{"id":"c","feedback":"Finely divided nickel is a catalyst; it does not cover or protect the handlebar."}],"explanation":"Nickel plating covers other metals, protecting them from oxidation and rust and giving them a beautiful appearance, which is what the handlebars need."}},"s6":{"m":{"explanation":"The reaction happens on the surface of the nickel. The same mass as a fine powder has a much larger total surface area than a lump, so finely divided nickel works better as a catalyst.","feedback_true":"No. The reaction happens on the surface. A fine powder of the same mass has a much larger surface, so more nickel touches the oil and hydrogen.","feedback_false":"Right. The same mass as a fine powder has a much larger surface, so more nickel touches the oil and hydrogen."}},"s7":{"c":{"items":[{"id":"hot","feedback":"Resisting corrosion at high temperature is the reason for Ni-Cr heating coils (step 3)."},{"id":"look","feedback":"Nickel plating gives other metals a beautiful appearance (step 2)."},{"id":"surf","feedback":"The finely divided nickel catalyst is a fine powder with a very large surface area (step 6)."},{"id":"rust","feedback":"Nickel plating covers other metals to protect them from oxidation and rust (step 2)."}],"explanation":"Coils: resist corrosion at high temperature. Plating: protects and looks beautiful. Powder: large surface area."},"q":{"options":[{"id":"a","feedback":"Right. Same mass, much more surface for the reaction."},{"id":"b","feedback":"That's the lump trap. The reaction happens on the surface, and the same mass as a fine powder has much more surface than lumps."},{"id":"c","feedback":"Each piece being heavy doesn't help: the reaction happens on the surface, and the total surface area in step 6 grows as the pieces get smaller."}],"explanation":"Both flasks have 5 g of nickel, but the finely divided nickel has a much larger surface area, and the reaction happens on the surface, so its flask is hydrogenated faster."}},"s8":{"ex":{"body":"Give reasons: Ni-Cr alloys in heating coils → **they resist corrosion at high temperature**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"صح: الملف السخن بيقابل الهوا طول اليوم، فلازم يقاوم الـ corrosion في درجات الحرارة العالية."},{"id":"b","feedback":"التوصيل مطلوب، لكن الملف السخن كمان بيقابل الهوا طول اليوم، والـ metal السخن بيتفاعل مع الهوا أسرع."},{"id":"c","feedback":"المغناطيس مش هو المشكلة في السشوار؛ الـ metal السخن بيقابل الهوا، واللي بيعمل فيه corrosion."}],"explanation":"الـ heating coil بيبقى سخن وبيقابل الهوا طول اليوم، والـ metal السخن بيتفاعل مع الهوا أسرع، فلازم الملف يقاوم الـ corrosion في درجات الحرارة العالية. وعشان كده الـ nickel-chromium alloys بتتستخدم في الـ heating coils."}},"s3":{"m":{"explanation":"الكتاب بيقول إن الـ nickel-chromium alloys بتتستخدم في الـ heating coils والـ electric furnaces عشان بتقاوم الـ corrosion في درجات الحرارة العالية، مش عشان توصيلها للكهربا.","feedback_true":"ده مش سبب الكتاب. الملف السخن بيقابل الهوا طول اليوم، فالكتاب بيقول إن الـ nickel-chromium alloys بتتستخدم عشان بتقاوم الـ corrosion في درجات الحرارة العالية. والـ copper توصيله أحسن، ومع كده مش بيتستخدم في الـ heating coils.","feedback_false":"صح. سبب الكتاب إن الـ nickel-chromium alloys بتقاوم الـ corrosion في درجات الحرارة العالية."}},"s4":{"q":{"options":[{"id":"a","feedback":"صح. ده سبب الكتاب لاستخدامها في الـ heating coils والـ electric furnaces."},{"id":"b","feedback":"ده الفخ المشهور: إن التوصيل كويس مش هو سبب الكتاب لاستخدام الـ alloy ده في الـ heating coils."},{"id":"c","feedback":"الشحن تاني ده خاص بالـ nickel-cadmium battery، مش بالـ heating coils."}],"explanation":"الملفات اللي بتفضل حمرا من السخونية ساعات محتاجة مادة بتقاوم الـ corrosion في درجات الحرارة العالية؛ وده سبب الكتاب لاستخدام الـ nickel-chromium alloys في الـ heating coils. أما الشحن تاني فده خاص بالـ nickel-cadmium battery."},"q2":{"options":[{"id":"a","feedback":"صح. الـ plating بيحمي من الـ oxidation والـ rust وبيدّي شكل حلو."},{"id":"b","feedback":"البطارية بتخزّن طاقة؛ مش بتحمي سطح الجادون ولا بتخليه يلمع."},{"id":"c","feedback":"الـ finely divided nickel ده catalyst؛ مش بيغطّي الجادون ولا بيحميه."}],"explanation":"الـ nickel plating بيغطّي الـ metals التانية، فبيحميها من الـ oxidation والـ rust وبيدّيها شكل حلو، ودي بالظبط احتياجات الجادون."}},"s6":{"m":{"explanation":"التفاعل بيحصل على سطح الـ nickel. نفس الكتلة لو بودرة ناعمة مساحة سطحها الكلية أكبر بكتير من الحتة الواحدة، فالـ finely divided nickel بيشتغل كـ catalyst أحسن.","feedback_true":"لأ. التفاعل بيحصل على السطح. البودرة الناعمة بنفس الكتلة سطحها أكبر بكتير، فـ nickel أكتر بيلمس الـ oil والـ hydrogen.","feedback_false":"صح. نفس الكتلة لو بودرة ناعمة سطحها أكبر بكتير، فـ nickel أكتر بيلمس الـ oil والـ hydrogen."}},"s7":{"c":{"items":[{"id":"hot","feedback":"مقاومة الـ corrosion في درجات الحرارة العالية هي سبب استخدام الـ Ni-Cr في الـ heating coils (الخطوة 3)."},{"id":"look","feedback":"الـ nickel plating بيدّي الـ metals التانية شكل حلو (الخطوة 2)."},{"id":"surf","feedback":"الـ finely divided nickel catalyst بودرة ناعمة مساحة سطحها كبيرة جدًا (الخطوة 6)."},{"id":"rust","feedback":"الـ nickel plating بيغطّي الـ metals التانية عشان يحميها من الـ oxidation والـ rust (الخطوة 2)."}],"explanation":"الملفات: بتقاوم الـ corrosion في درجات الحرارة العالية. الـ plating: بيحمي وشكله حلو. البودرة: مساحة سطحها كبيرة."},"q":{"options":[{"id":"a","feedback":"صح. نفس الكتلة، لكن مساحة سطح أكبر بكتير للتفاعل."},{"id":"b","feedback":"ده فخ الحتت الكبيرة. التفاعل بيحصل على السطح، ونفس الكتلة لو بودرة ناعمة سطحها أكبر بكتير من الحتت."},{"id":"c","feedback":"إن كل حتة تقيلة ده مش هيفيد: التفاعل بيحصل على السطح، ومساحة السطح الكلية في الخطوة 6 بتكبر كل ما الحتت تصغر."}],"explanation":"الدورقين فيهم 5 g من الـ nickel، لكن الـ finely divided nickel مساحة سطحه أكبر بكتير، والتفاعل بيحصل على السطح، فالـ hydrogenation في الدورق بتاعه بيبقى أسرع."}},"s8":{"ex":{"body":"علّل: الـ Ni-Cr alloys بتتستخدم في الـ heating coils ← **عشان بتقاوم الـ corrosion في درجات الحرارة العالية**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":6,"lesson_no":19,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-uses","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Economic importance of the first transition series","duration_s":767.019,"start_s":545.8,"end_s":607.4,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.uses-ni","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Economic importance of nickel","duration_s":47.87,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.uses-cu-zn","kind":"lesson","version":3,"catalog_version":3,"ord":114,"primary_concept_id":"te.uses-cu-zn","concepts":[{"concept_id":"te.uses-cu-zn","role":"primary"}],"title":"Economic importance of copper and zinc","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"tin","correct":true},{"id":"b","text":"zinc","correct":false},{"id":"c","text":"iron","correct":false}],"question":"Predict: bronze is an alloy (a metal mixed with other elements) of copper and…"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Ancient Egyptians made tools and statues of bronze thousands of years ago. What is bronze made of?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"The first metal"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"br","from":"cu","label":"alloy with tin"},{"to":"ca","from":"cu","label":"good conductor"},{"to":"co","from":"cu"}],"nodes":[{"id":"cu","label":"Copper"},{"id":"br","label":"Bronze (copper + tin)"},{"id":"ca","label":"Electric cables"},{"id":"co","label":"Coins"}],"caption":"Copper uses (book p.7)"},"children":[]},"book":{"type":"Text","props":{"content":"Copper is the **first discovered metal**. Copper-tin alloys are known as **bronze**. Copper is a **good conductor of electricity**, so it is used in **electric cables** and the **coins industry**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["book","fd","m"]}}},"title":"9- Copper"},{"id":"s3","kind":"explain","spec":{"root":"root","state":{"g":0},"elements":{"t":{"type":"Text","props":{"content":"**Fehling's solution** is one of the copper compounds. It is used to detect **glucose**. Slide to add glucose and heat."},"children":[]},"sl":{"type":"Slider","props":{"max":1,"min":0,"step":1,"label":"Glucose added (0 = no, 1 = yes)","value":{"$bindState":"/g"}},"children":[]},"blue":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 160 200\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><path d=\"M55 20 L55 150 Q55 178 80 178 Q105 178 105 150 L105 20\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><path d=\"M57 80 L57 150 Q57 176 80 176 Q103 176 103 150 L103 80 Z\" fill=\"#3b82f6\" fill-opacity=\"0.85\"/><text x=\"80\" y=\"196\" text-anchor=\"middle\" font-size=\"13\" fill=\"#e2e8f0\">Fehling's solution: blue</text></svg>","caption":"No glucose: it stays blue","max_width":170},"visible":{"eq":0,"$state":"/g"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","blue","orange"]},"orange":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 160 200\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><path d=\"M55 20 L55 150 Q55 178 80 178 Q105 178 105 150 L105 20\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><path d=\"M57 80 L57 150 Q57 176 80 176 Q103 176 103 150 L103 80 Z\" fill=\"#f97316\" fill-opacity=\"0.85\"/><text x=\"80\" y=\"196\" text-anchor=\"middle\" font-size=\"13\" fill=\"#e2e8f0\">With glucose: orange</text></svg>","caption":"Glucose: the blue colour changes to orange","max_width":170},"visible":{"eq":1,"$state":"/g"},"children":[]}}},"title":"Fehling's solution"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"No glucose was detected","correct":true},{"id":"b","text":"Glucose is present","correct":false},{"id":"c","text":"The drink contains copper","correct":false}],"question":"A student tests a sugar-free drink with Fehling's solution and heats it. It stays blue. What does that show?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["m","q"]}}},"title":"Read the test"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Galvanizing","definition":"Coating other metals with zinc to protect them from rusting."},"children":[]},"t":{"type":"Text","props":{"content":"Zinc is used in **galvanizing other metals** to protect them from rusting. Think of the grey iron sheets on many rooftops."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"zn","from":"fe","label":"galvanizing"},{"to":"ok","from":"zn"}],"nodes":[{"id":"fe","label":"Iron (rusts in moist air)"},{"id":"zn","label":"Iron coated with zinc"},{"id":"ok","label":"Protected from rusting"}],"caption":"Galvanizing"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["recall","k","t","fd"]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: iron rusts in moist air."},"children":[]}}},"title":"10- Zinc: galvanizing"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"tab":{"type":"DataTable","props":{"rows":[["Copper II sulphate ($\\ce{CuSO4}$)","insecticide and fungicide, in the purification of water"],["Zinc oxide (ZnO)","manufacture of paints, rubber and cosmetics"],["Zinc sulphide (ZnS)","manufacture of illuminating paints and X-ray screens"]],"caption":"Compounds of copper and zinc (book pp.7-8)","headers":["Compound","Use"]},"children":[]},"tip":{"type":"Callout","props":{"variant":"tip"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tab","recall","tip"]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: X-rays are invisible. A ZnS screen glows where they hit it, so we can see the picture."},"children":[]}}},"title":"Copper and zinc compounds"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"cab","text":"Electric cables"},{"id":"glu","text":"Detecting glucose"},{"id":"ins","text":"Insecticide and fungicide"},{"id":"gal","text":"Galvanizing iron"},{"id":"xr","text":"X-ray screens"},{"id":"pnt","text":"Paints, rubber and cosmetics"}],"answer":{"cu":["cab"],"zn":["gal"],"cuc":["glu","ins"],"znc":["xr","pnt"]},"prompt":"Sort each use under the metal or its compounds.","categories":[{"id":"cu","label":"Copper"},{"id":"cuc","label":"Copper compounds"},{"id":"zn","label":"Zinc"},{"id":"znc","label":"Zinc compounds"}]},"children":[]},"fb":{"type":"FillBlank","props":{"text":"Bronze is an alloy of copper and ___.","answers":[["tin","sn"]],"mistakes":[{"id":"m1","blank":0,"answer":"zinc"},{"id":"m2","blank":0,"answer":"iron"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","fb"]}}},"title":"Copper or zinc?"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Cu: the first discovered metal; bronze = copper-tin alloys; cables and coins (good conductor).","$\\ce{CuSO4}$: insecticide, fungicide, water purification. Fehling's: blue to orange with glucose.","Zn: galvanizing other metals against rust.","ZnO: paints, rubber, cosmetics. ZnS: illuminating paints and X-ray screens."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"rv":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Why a Fehling's test that stays blue means no glucose"}},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"Fehling's solution starts blue, and glucose changes the blue colour to orange. If it stays blue, the colour did not change, so no glucose was detected."},"children":[]},"hook":{"type":"Text","props":{"content":"Back to the hook: ancient bronze is copper + tin."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["hook","b","ex","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why a Fehling's test that stays blue means no glucose?"},"children":[]}}},"title":"Summary"}],"title":"Economic importance of copper and zinc","minutes":9,"book_ref":"Ch.1 economic importance: 9-Copper, 10-Zinc, pp.7-8","subtitle":"Ancient bronze, modern cables and galvanized iron","objectives":["State the uses of copper: bronze (copper-tin alloys), electric cables and coins.","State the uses of copper II sulphate and Fehling's solution (detecting glucose: blue to orange).","State the uses of zinc (galvanizing) and its compounds ZnO and ZnS."],"concept_ids":["te.uses-cu-zn"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Right. Copper-tin alloys are known as bronze."},{"id":"b","feedback":"That's a very common guess, but copper with zinc makes a different alloy; step 2 comes back to it."},{"id":"c","feedback":"Iron came into wide use much later, and bronze is older."}],"explanation":"Bronze is an alloy of copper and tin: the book says copper-tin alloys are known as bronze."}},"s2":{"m":{"statement":"Bronze is copper + zinc.","correction":"Bronze is **copper + tin**. Copper with zinc gives a different alloy."}},"s4":{"m":{"statement":"Fehling's solution turns blue with glucose.","correction":"Fehling's solution **starts** blue. Glucose changes the blue colour to orange."},"q":{"options":[{"id":"a","feedback":"Right. The colour change to orange is the sign of glucose."},{"id":"b","feedback":"Blue is the starting colour of the solution; glucose would change it to orange."},{"id":"c","feedback":"The copper is in Fehling's solution itself; the test looks for glucose."}],"explanation":"The test detected no glucose. Fehling's solution starts blue, and glucose changes the blue colour to orange; a solution that stays blue shows no glucose."}},"s6":{"tip":{"body":"O or S? Zinc **oxide**: paints, rubber, cosmetics. Zinc **sulphide**: things that glow."}},"s7":{"c":{"items":[{"id":"cab","feedback":"Electric cables use the metal itself, the good conductor of this lesson, not one of its compounds."},{"id":"glu","feedback":"Glucose is detected with Fehling's solution (step 3), which holds the metal in a compound, not as the metal itself."},{"id":"ins","feedback":"The insecticide and fungicide is a sulphate, $\\ce{CuSO4}$ (step 6), not the metal itself."},{"id":"gal","feedback":"Galvanizing coats iron against rust with the metal itself, not with a compound."},{"id":"xr","feedback":"X-ray screens use a sulphide that glows (step 6): a compound, not the metal."},{"id":"pnt","feedback":"Paints, rubber and cosmetics use an oxide (step 6): a compound, not the metal."}],"explanation":"Cu: cables. Cu compounds: Fehling's solution (glucose), $\\ce{CuSO4}$. Zn: galvanizing. Zn compounds: ZnS screens, ZnO paints."},"fb":{"mistakes":[{"id":"m1","feedback":"Copper with zinc makes a different alloy, not bronze."},{"id":"m2","feedback":"Iron is not in bronze; bronze is copper with a soft, silvery metal."}],"explanation":"Bronze = copper + tin."}},"s8":{"ex":{"body":"Key words: **bronze = copper + tin**, **good conductor of electricity**, **blue changes to orange**, **galvanizing**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"صح. الـ alloys اللي من copper و tin اسمها bronze."},{"id":"b","feedback":"ده تخمين ناس كتير بتقع فيه. الـ copper مع الـ zinc بيدّوا alloy تاني، والخطوة 2 بتتكلم عنه."},{"id":"c","feedback":"الـ iron انتشر استخدامه بعد كده بكتير، والـ bronze أقدم منه. الـ metal التاني في الـ bronze metal طري ولونه فضي."}],"explanation":"الـ bronze هو alloy من الـ copper والـ tin: الكتاب بيقول إن الـ alloys اللي من copper و tin اسمها bronze."}},"s2":{"m":{"statement":"الـ bronze هو copper + zinc.","correction":"الـ bronze هو **copper + tin**. أما الـ copper مع الـ zinc فبيدّوا alloy تاني."}},"s4":{"m":{"statement":"الـ Fehling's solution بيبقى أزرق لما يتحط عليه glucose.","correction":"الـ Fehling's solution لونه أزرق **من الأول**. والـ glucose هو اللي بيغيّر اللون الأزرق لبرتقاني."},"q":{"options":[{"id":"a","feedback":"صح. تغيّر اللون للبرتقاني هو العلامة إن فيه glucose."},{"id":"b","feedback":"الأزرق ده لون الـ solution من الأول، والـ glucose هو اللي بيغيّره لبرتقاني."},{"id":"c","feedback":"الـ copper موجود في الـ Fehling's solution نفسه، والـ test ده بيكشف عن الـ glucose."}],"explanation":"مفيش glucose اتكشف. الـ Fehling's solution لونه أزرق من الأول، والـ glucose هو اللي بيغيّر الأزرق لبرتقاني؛ فلما الـ solution يفضل أزرق يبقى مفيش glucose ظهر."}},"s6":{"tip":{"body":"O ولا S؟ الـ zinc **oxide**: للدهانات والـ rubber ومستحضرات التجميل. الـ zinc **sulphide**: للحاجات اللي بتنوّر."}},"s7":{"c":{"items":[{"id":"cab","feedback":"الكابلات الكهربا بتتعمل من metal نقي موصّل ممتاز للكهربا، مش من compound، وده اللي في الخطوة 2."},{"id":"glu","feedback":"الـ Fehling's solution ده compound مش metal نقي، وده اللي اتشرح في الخطوة 3."},{"id":"ins","feedback":"اللي بيموّت الحشرات والفطريات هو الـ $\\ce{CuSO4}$، يعني compound مش metal (الخطوة 6)."},{"id":"gal","feedback":"الـ galvanizing هو تغطية الـ iron بطبقة من metal نقي تحميه من الصدأ، وده اللي في الخطوة 5."},{"id":"xr","feedback":"شاشات الـ X-ray بتستخدم الـ ZnS اللي بينوّر، يعني compound مش metal (الخطوة 6)."},{"id":"pnt","feedback":"الدهانات والـ rubber ومستحضرات التجميل بتستخدم الـ ZnO، يعني compound مش metal (الخطوة 6)."}],"explanation":"الـ Cu: الكابلات. الـ Cu compounds: الـ Fehling's solution (للـ glucose)، والـ $\\ce{CuSO4}$. الـ Zn: الـ galvanizing. الـ Zn compounds: شاشات الـ ZnS، ودهانات الـ ZnO."},"fb":{"mistakes":[{"id":"m1","feedback":"الـ copper مع الـ zinc بيدّوا alloy تاني غير الـ bronze."},{"id":"m2","feedback":"الـ iron مش داخل في الـ bronze؛ الـ bronze بيتعمل من الـ copper مع metal طري."}],"explanation":"الـ bronze = copper + tin."}},"s8":{"ex":{"body":"الكلمات اللي بتيجي في الامتحان: **bronze = copper + tin**، **good conductor of electricity**، **blue changes to orange**، **galvanizing**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":7,"lesson_no":20,"lesson_count":20,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-uses","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Economic importance of the first transition series","duration_s":767.019,"start_s":615.5,"end_s":683.4,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.uses-cu-zn","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Economic importance of copper and zinc","duration_s":43.34,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General 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orbital, but with opposite spins ($\\uparrow\\ \\downarrow\\ \\uparrow$)","correct":false}],"question":"Predict before you see it:"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Nitrogen has 3 electrons in its 2p sublevel, and 2p has 3 empty orbitals. How will the electrons sit?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","boxes","q"]},"boxes":{"type":"ElectronBoxes","props":{"groups":[{"fill":["","",""],"boxes":3,"label":"2p"}],"caption":"$\\ce{_7N}$: $1s^2\\ 2s^2\\ 2p^3$"},"children":[]}}},"title":"Three electrons, three empty orbitals"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"why":{"type":"Text","props":{"content":"Why? Electrons are negative and repel each other. When they stay apart in separate orbitals, the energy is lower."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["recall","term","boxes","why"]},"term":{"type":"Card","props":{"tone":"brand","title":"Hund's rule"},"children":["termdef"]},"boxes":{"type":"ElectronBoxes","props":{"groups":[{"boxes":3,"label":"2p","electrons":3}],"caption":"$\\ce{_7N}$: $2p^3$ = 3 unpaired electrons","show_unpaired":true},"children":[]},"recall":{"type":"Text","props":{"muted":true,"content":"Remember: an orbital holds 2 electrons at most, and the two have opposite spins ($\\uparrow\\downarrow$)."},"children":[]},"termdef":{"type":"Text","props":{"content":"Electrons occupy the orbitals of the same sublevel **singly** first, with **parallel spins**, before **pairing** starts."},"children":[]}}},"title":"Hund's rule"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"n":1},"elements":{"t":{"type":"Text","props":{"content":"The d sublevel has 5 orbitals. Add electrons one at a time and watch the number of unpaired electrons."},"children":[]},"d0":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":0}],"caption":"$d^{0}$"},"visible":{"eq":0,"$state":"/n"},"children":[]},"d1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":1}],"caption":"$d^{1}$"},"visible":{"eq":1,"$state":"/n"},"children":[]},"d2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":2}],"caption":"$d^{2}$"},"visible":{"eq":2,"$state":"/n"},"children":[]},"d3":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":3}],"caption":"$d^{3}$"},"visible":{"eq":3,"$state":"/n"},"children":[]},"d4":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":4}],"caption":"$d^{4}$"},"visible":{"eq":4,"$state":"/n"},"children":[]},"d5":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":5}],"caption":"$d^{5}$"},"visible":{"eq":5,"$state":"/n"},"children":[]},"d6":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":6}],"caption":"$d^{6}$"},"visible":{"eq":6,"$state":"/n"},"children":[]},"d7":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":7}],"caption":"$d^{7}$"},"visible":{"eq":7,"$state":"/n"},"children":[]},"d8":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":8}],"caption":"$d^{8}$"},"visible":{"eq":8,"$state":"/n"},"children":[]},"d9":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":9}],"caption":"$d^{9}$"},"visible":{"eq":9,"$state":"/n"},"children":[]},"sl":{"type":"Slider","props":{"max":10,"min":0,"step":1,"label":"Electrons in the d sublevel","value":{"$bindState":"/n"}},"children":[]},"d10":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":10}],"caption":"$d^{10}$"},"visible":{"eq":10,"$state":"/n"},"children":[]},"obs":{"type":"BulletList","props":{"items":["From $d^1$ to $d^5$: each new electron goes into an empty orbital, so the number of unpaired electrons goes up.","From $d^6$ to $d^{10}$: each new electron makes a pair, so the number of unpaired electrons goes down to zero."]},"children":[]},"rev":{"type":"Reveal","props":{},"children":["obs"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","d0","d1","d2","d3","d4","d5","d6","d7","d8","d9","d10","stat","rev"]},"stat":{"type":"Stat","props":{"tone":"brand","label":"unpaired electrons","value":{"args":{"n":{"$state":"/n"},"expr":"min(n, 10 - n)","digits":0},"$computed":"calc"}},"children":[]}}},"title":"Fill the d sublevel yourself"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q1":{"type":"MCQ","props":{"options":[{"id":"a","text":"0","correct":false},{"id":"b","text":"4","correct":true},{"id":"c","text":"6","correct":false},{"id":"d","text":"2","correct":false}],"question":"A sublevel has 6 electrons ($d^6$). How many unpaired electrons does it have?"},"children":[]},"q2":{"type":"MCQ","props":{"options":[{"id":"a","text":"$[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\ \\ ]$","correct":false},{"id":"b","text":"$[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow][\\uparrow]$","correct":true},{"id":"c","text":"$[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow][\\downarrow]$","correct":false}],"question":"Which diagram is correct for $d^8$?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q1","q2","hints"]},"hints":{"type":"HintLadder","props":{},"children":[]}}},"title":"Count the unpaired electrons"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Hund's rule: singly and with parallel spins first, then pairing.","The reason: electrons repel each other, so spreading out gives a lower energy.","Quick count: $d^5$ = 5 unpaired, $d^6$ = 4, $d^8$ = 2, $d^{10}$ = 0."]},"children":[]},"eb5":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d, 5 electrons","electrons":5}],"show_unpaired":true},"children":[]},"eb6":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d, 6 electrons","electrons":6}],"show_unpaired":true},"children":[]},"eb8":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d, 8 electrons","electrons":8}],"caption":"$d^5$ = 5 unpaired, $d^6$ = 4, $d^8$ = 2","show_unpaired":true},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"next":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Where will you use it?"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","eb5","eb6","eb8","exam","next","self"]},"self":{"type":"Text","props":{"content":"Can you explain in one sentence why nitrogen has 3 unpaired electrons, not just 1?"},"children":[]}}},"title":"Summary"}],"title":"Hund's rule: one electron in each orbital first","minutes":4,"book_ref":"Ch.1 Electronic configurations, point 1 (Hund's rule applied to 3d), p.8; prerequisite from earlier grades","subtitle":"The key you need to draw the 3d boxes","objectives":["Draw the electrons of any p or d sublevel in boxes using Hund's rule: one electron in each orbital with parallel spins, then pairing.","Count the unpaired electrons in any p or d sublevel (for example, $d^6$ = 4 and $d^8$ = 2)."],"concept_ids":["atom.hund-rule"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"This is the most common guess: fill the first orbital first. But electrons are all negative, so they repel each other; while an empty orbital of the same sublevel is free, an electron does not pair up."},{"id":"b","feedback":"Exactly: each electron takes an empty orbital, and the spins are parallel. This is Hund's rule. In the next step you will see why."},{"id":"c","feedback":"Half right: each electron is in its own orbital. But an opposite spin ($\\downarrow$) is only needed when two electrons share the same orbital. When they are in separate orbitals, their spins are parallel."}],"explanation":"By Hund's rule, each of the three 2p electrons takes its own orbital, all with the same (parallel) spin: $\\uparrow\\ \\uparrow\\ \\uparrow$. Electrons repel each other, so they occupy the orbitals of the sublevel singly before pairing starts."}},"s4":{"q1":{"options":[{"id":"a","feedback":"You get 0 if you draw 3 pairs in a row ($\\uparrow\\downarrow\\ \\uparrow\\downarrow\\ \\uparrow\\downarrow$) and leave orbitals empty. That is pairing before every orbital has one electron, which breaks Hund's rule."},{"id":"b","feedback":"Correct: the first five go in singly, and the sixth pairs with the first one, so 4 electrons stay unpaired."},{"id":"c","feedback":"This puts every electron in its own orbital, but d has only 5 orbitals, so the sixth electron must share one."},{"id":"d","feedback":"It looks like pairing started too early. In Hund's rule, pairing starts only after all 5 orbitals have one electron each."}],"explanation":"$d^6$: $[\\uparrow\\downarrow][\\uparrow][\\uparrow][\\uparrow][\\uparrow]$, so 4 unpaired electrons."},"q2":{"options":[{"id":"a","feedback":"Here electrons paired while the last orbital is still empty. Hund's rule fills every orbital of the sublevel singly first, so that empty orbital breaks the rule."},{"id":"b","feedback":"Correct: 5 singly, then 3 make pairs, so 2 unpaired electrons are left."},{"id":"c","feedback":"The numbers are right, but the two unpaired electrons must have the same spin (parallel). A $\\downarrow$ appears only inside a pair."}],"explanation":"8 = 5 singly + 3 that make pairs. The 2 unpaired electrons have parallel spins."},"hints":{"hints":["Start by putting one electron in each box.","After the first 5, each extra electron pairs with the first box that has only one arrow.","Count the boxes that have only one arrow."]}},"s5":{"exam":{"body":"**Hund's rule**: electrons occupy the orbitals of the same sublevel **singly**, with parallel spins, before **pairing** starts."},"next":{"body":"To fill the 3d sublevel in the first transition series."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"دي أشهر توقّع: تملا أول orbital الأول. لكن الـ electrons كلها negative، فبتتنافر مع بعض؛ وطول ما فيه orbital فاضي في نفس الـ sublevel، الـ electron مش بيعمل زوج."},{"id":"b","feedback":"بالظبط: كل electron بياخد orbital فاضي، والـ spins بتبقى parallel. دي الـ Hund's rule. وفي الخطوة الجاية هتشوف ليه."},{"id":"c","feedback":"نص الإجابة صح: كل electron في orbital لوحده. لكن الـ spin العكسي ($\\downarrow$) محتاجينه لما اتنين electrons يشتركوا في نفس الـ orbital تحديدًا. طول ما هما في orbitals منفصلة، الـ spins بتاعتهم بتبقى parallel."}],"explanation":"حسب الـ Hund's rule، كل electron من التلاتة اللي في الـ 2p بياخد orbital لوحده، وكلهم بنفس الـ spin (parallel): $\\uparrow\\ \\uparrow\\ \\uparrow$. الـ electrons بتتنافر مع بعض، فبتملا orbitals الـ sublevel فرادى قبل ما الأزواج تبتدي."}},"s4":{"q1":{"options":[{"id":"a","feedback":"هتطلع 0 لو رسمت 3 أزواج ورا بعض ($\\uparrow\\downarrow\\ \\uparrow\\downarrow\\ \\uparrow\\downarrow$) وسبت orbitals فاضية. ده إنك عملت أزواج قبل ما كل orbital ياخد electron واحد، وده عكس الـ Hund's rule."},{"id":"b","feedback":"مظبوط: أول خمسة بيدخلوا فرادى، والسادس بيعمل زوج مع الأول، فيفضل 4 electrons unpaired."},{"id":"c","feedback":"كده إنت حطيت كل electron في orbital لوحده، لكن الـ d فيه 5 orbitals لا أكتر، فالـ electron السادس لازم يشارك واحد."},{"id":"d","feedback":"شكل الأزواج ابتدت بدري. في الـ Hund's rule، الأزواج مش بتبتدي غير بعد ما الـ 5 orbitals ياخدوا electron واحد كل واحد فيهم."}],"explanation":"$d^6$: $[\\uparrow\\downarrow][\\uparrow][\\uparrow][\\uparrow][\\uparrow]$، يعني 4 unpaired electrons."},"q2":{"options":[{"id":"a","feedback":"هنا الـ electrons عملوا أزواج والـ orbital الأخير لسه فاضي. الـ Hund's rule بتملا كل orbitals الـ sublevel فرادى الأول، فالـ orbital الفاضي ده عكس القاعدة."},{"id":"b","feedback":"مظبوط: 5 فرادى، وبعدين 3 بيعملوا أزواج، فيفضل 2 unpaired electrons."},{"id":"c","feedback":"الأعداد صح، لكن الـ 2 unpaired electrons لازم يبقى ليهم نفس الـ spin (parallel). الـ $\\downarrow$ مابيظهرش غير جوه زوج."}],"explanation":"الـ 8 = 5 فرادى + 3 بيعملوا أزواج. والـ 2 unpaired electrons الـ spins بتاعتهم parallel."},"hints":{"hints":["ابدأ إنك تحط electron واحد في كل مربع.","بعد أول 5، كل electron زيادة بيعمل زوج مع أول مربع فيه سهم واحد لوحده.","عدّ المربعات اللي فيها سهم واحد لوحده."]}},"s5":{"exam":{"body":"**الـ Hund's rule**: الـ electrons بتملا الـ orbitals بتاعة نفس الـ sublevel **فرادى** الأول، بـ parallel spins، وبعد كده يبدأ الـ **pairing**."},"next":{"body":"عشان تملا الـ 3d sublevel في الـ first transition series."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":1,"is_basics":true,"lesson_no":1,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-configuration","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Electronic configurations and oxidation states","duration_s":717.229,"start_s":39.8,"end_s":55.9,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-atom.hund-rule","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Hund's rule and orbital-box diagrams","duration_s":52.59,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 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Each one has one electron more than the element before it. Where does that electron go?"},"children":[]},"ca":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":0}],"caption":"$\\ce{_{20}Ca}$: $[\\text{Ar}]\\ 4s^2$ (3d is still empty)"},"children":[]},"pt":{"type":"PeriodicTable","props":{"labels":{"Ca":"[Ar] 4s², before the series"},"caption":"The first transition series: Sc to Zn, in the fourth period after Ca","highlight_symbols":["Ca","Sc","Ti","V","Cr","Mn","Fe","Co","Ni","Cu","Zn"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","pt","ca","q"]}}},"title":"Where does the extra electron go?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"$[\\text{Ar}]$ is short for the first 18 electrons. After it comes $4s^2$, which was filled at Ca, and then 3d."},"children":[]},"bx":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":1}],"caption":"$\\ce{Sc}$: one electron in 3d"},"children":[]},"gen":{"type":"Formula","props":{"latex":"[\\text{Ar}]\\ 4s^2\\ 3d^{\\,Z-20}","caption":"General pattern: number of 3d electrons = Z − 20 (except Cr and Cu)"},"children":[]},"full":{"type":"Formula","props":{"latex":"\\ce{_{21}Sc}:\\ 1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6\\ 4s^2\\ 3d^1","caption":"Full configuration"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","full","short","bx","gen"]},"short":{"type":"Formula","props":{"latex":"\\ce{_{21}Sc}:\\ [\\text{Ar}]\\ 4s^2\\ 3d^1","caption":"The same configuration, shortened, in the order of the book's table: 4s, then 3d"},"children":[]}}},"title":"The general pattern"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"r1":{"type":"Reveal","props":{"label":"Step 1: Take away the [Ar]"},"children":["r1t"]},"r2":{"type":"Reveal","props":{"label":"Step 2: Share them between 4s and 3d"},"children":["r2t","r2f"]},"r3":{"type":"Reveal","props":{"label":"Step 3: Draw the boxes"},"children":["r3t","r3b"]},"r1t":{"type":"Text","props":{"content":"$26 - 18 = 8$ electrons are left after $[\\text{Ar}]$, because $[\\text{Ar}]$ = the first 18 electrons."},"children":[]},"r2f":{"type":"Formula","props":{"latex":"\\ce{_{26}Fe}:\\ [\\text{Ar}]\\ 4s^2\\ 3d^6"},"children":[]},"r2t":{"type":"Text","props":{"content":"The first 2 go to $4s$ (just like Ca), and the other 6 go to $3d$."},"children":[]},"r3b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":6}],"caption":"$3d^6$: 4 unpaired electrons","show_unpaired":true},"children":[]},"r3t":{"type":"Text","props":{"content":"Hund's rule: the first five go in singly, and the sixth pairs with the first one."},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["r1","r2","r3","trap"]},"trap":{"type":"Misconception","props":{},"children":[]}}},"title":"Worked example: Fe (Z = 26)"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Same steps. Step 1 is done for you: $27 - 18 = 9$ electrons after $[\\text{Ar}]$."},"children":[]},"bx":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":7}],"caption":"$\\ce{_{27}Co}$: $[\\text{Ar}]\\ 4s^{2}\\ 3d^{7}$","show_unpaired":true},"children":[]},"fb":{"type":"FillBlank","props":{"text":"The first ___ electrons go to 4s, and the rest (___) go to 3d. So 3d has ___ unpaired electrons.","answers":[["2","two"],["7","seven"],["3","three"]],"mistakes":[{"id":"m1","blank":0,"answer":"1"},{"id":"m2","blank":1,"answer":"9"},{"id":"m3","blank":2,"answer":"1"},{"id":"m4","blank":2,"answer":"7"},{"id":"m5","blank":2,"answer":"5"}]},"children":[]},"rv":{"type":"Reveal","props":{"label":"Show the boxes"},"children":["bx"]},"root":{"type":"Stack","props":{"gap":"md"},"children":["t","fb","hints","rv"]},"hints":{"type":"HintLadder","props":{},"children":[]}}},"title":"Your turn: Co (Z = 27)"},{"id":"s5","kind":"interact","spec":{"root":"root","state":{"z":21},"elements":{"t":{"type":"Text","props":{"content":"Move the slider from Sc to Zn. Watch the 3d boxes and the number of unpaired electrons."},"children":[]},"rv":{"type":"Reveal","props":{"label":"Tried all ten? Tap to see the pattern"},"children":["obs"]},"sl":{"type":"Slider","props":{"max":30,"min":21,"step":1,"label":"Z (atomic number)","value":{"$bindState":"/z"}},"children":[]},"obs":{"type":"BulletList","props":{"items":["The five 3d orbitals are filled singly up to Mn ($3d^5$).","After Mn, pairing takes place up to Zn ($3d^{10}$).","Cr and Cu are the exceptions: $4s^1$, as the book writes them.","So 4s can change too. Compare Cr and Mn: both are $3d^5$, but 4s goes from 1 to 2."]},"children":[]},"z21":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":1}],"caption":"$\\ce{_{21}Sc}$: $[\\text{Ar}]\\ 4s^{2}\\ 3d^{1}$","show_unpaired":true},"visible":{"eq":21,"$state":"/z"},"children":[]},"z22":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":2}],"caption":"$\\ce{_{22}Ti}$: $[\\text{Ar}]\\ 4s^{2}\\ 3d^{2}$","show_unpaired":true},"visible":{"eq":22,"$state":"/z"},"children":[]},"z23":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":3}],"caption":"$\\ce{_{23}V}$: $[\\text{Ar}]\\ 4s^{2}\\ 3d^{3}$","show_unpaired":true},"visible":{"eq":23,"$state":"/z"},"children":[]},"z24":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":5}],"caption":"$\\ce{_{24}Cr}$: $[\\text{Ar}]\\ 4s^{1}\\ 3d^{5}$ (one of the book's two exceptions; it has its own lesson)","show_unpaired":true},"visible":{"eq":24,"$state":"/z"},"children":[]},"z25":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":5}],"caption":"$\\ce{_{25}Mn}$: $[\\text{Ar}]\\ 4s^{2}\\ 3d^{5}$","show_unpaired":true},"visible":{"eq":25,"$state":"/z"},"children":[]},"z26":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":6}],"caption":"$\\ce{_{26}Fe}$: $[\\text{Ar}]\\ 4s^{2}\\ 3d^{6}$","show_unpaired":true},"visible":{"eq":26,"$state":"/z"},"children":[]},"z27":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":7}],"caption":"$\\ce{_{27}Co}$: $[\\text{Ar}]\\ 4s^{2}\\ 3d^{7}$","show_unpaired":true},"visible":{"eq":27,"$state":"/z"},"children":[]},"z28":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":8}],"caption":"$\\ce{_{28}Ni}$: $[\\text{Ar}]\\ 4s^{2}\\ 3d^{8}$","show_unpaired":true},"visible":{"eq":28,"$state":"/z"},"children":[]},"z29":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":10}],"caption":"$\\ce{_{29}Cu}$: $[\\text{Ar}]\\ 4s^{1}\\ 3d^{10}$ (one of the book's two exceptions; it has its own lesson)","show_unpaired":true},"visible":{"eq":29,"$state":"/z"},"children":[]},"z30":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":10}],"caption":"$\\ce{_{30}Zn}$: $[\\text{Ar}]\\ 4s^{2}\\ 3d^{10}$","show_unpaired":true},"visible":{"eq":30,"$state":"/z"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","z21","z22","z23","z24","z25","z26","z27","z28","z29","z30","rv"]}}},"title":"The whole series in your hands"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"The book says it clearly: the five 3d orbitals are filled singly up to Mn ($3d^5$). After Mn, pairing takes place up to Zn ($3d^{10}$)."},"children":[]},"b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":5}],"caption":"$3d^5$: every orbital has one electron","show_unpaired":true},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":6}],"caption":"$3d^6$: the first pair in the series","show_unpaired":true},"children":[]},"c1":{"type":"Card","props":{"tone":"info","title":"Mn (Z = 25)"},"children":["b1"]},"c2":{"type":"Card","props":{"tone":"success","title":"Fe (Z = 26)"},"children":["b2"]},"cols":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["trap","cols","t"]},"trap":{"type":"Misconception","props":{},"children":[]}}},"title":"Why no early pairing?"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$4s\\,[\\uparrow\\downarrow]\\quad 3d\\,[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\ \\ ]$","correct":false},{"id":"b","text":"$4s\\,[\\uparrow\\downarrow]\\quad 3d\\,[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow][\\uparrow]$","correct":true},{"id":"c","text":"$4s\\,[\\ \\ ]\\quad 3d\\,[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow]$","correct":false},{"id":"d","text":"$4s\\,[\\uparrow]\\quad 3d\\,[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow]$","correct":false}],"question":"$\\ce{_{28}Ni}$: which diagram of 4s and 3d is correct?"},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["q","hints"]},"hints":{"type":"HintLadder","props":{},"children":[]}}},"title":"Draw Ni"},{"id":"s8","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$[\\text{Ar}]\\ 3d^3$","correct":false},{"id":"b","text":"$[\\text{Ar}]\\ 3d^5$","correct":false},{"id":"c","text":"$[\\text{Ar}]\\ 4s^2\\ 3d^3$","correct":true},{"id":"d","text":"$[\\text{Ar}]\\ 4s^1\\ 3d^4$","correct":false}],"question":"Which configuration is correct for $\\ce{_{23}V}$?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"Full configuration of Ti (Z = 22): $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6$ 4s___ 3d___ (type the exponents)","answers":[["2"],["2"]],"mistakes":[{"id":"m1","blank":0,"answer":"0"},{"id":"m2","blank":1,"answer":"4"},{"id":"m3","blank":0,"answer":"1"},{"id":"m4","blank":1,"answer":"3"},{"id":"m5","blank":1,"answer":"1"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","fb","hints"]},"hints":{"type":"HintLadder","props":{},"children":[]}}},"title":"Write the configuration"},{"id":"s9","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["From Sc to Zn the 3d sublevel is filled successively. General pattern: $[\\text{Ar}]\\ 4s^2\\ 3d^{\\,Z-20}$.","3d follows Hund's rule: singly up to Mn ($3d^5$), then pairing up to Zn ($3d^{10}$).","In an atom, never leave out 4s: the electrons must add up to Z.","Two exceptions: $\\ce{_{24}Cr}$: $[\\text{Ar}]\\ 4s^1\\ 3d^5$ and $\\ce{_{29}Cu}$: $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$ (the reason is in its own lesson)."]},"children":[]},"ans":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Why 4 unpaired electrons in Fe"}},"children":["ans_t","ans_b"]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why Fe has 4 unpaired electrons in 3d, not just 2?"},"children":[]},"ans_b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":6}],"caption":"$3d^6$: 4 unpaired electrons","show_unpaired":true},"children":[]},"ans_t":{"type":"Text","props":{"content":"$\\ce{_{26}Fe}$: $[\\text{Ar}]\\ 4s^2\\ 3d^6$. By Hund's rule the first five 3d electrons go in singly, and only the sixth pairs with the first one, so 4 electrons stay unpaired."},"children":[]}}},"title":"Summary"}],"title":"Electronic configuration of the first transition series","minutes":9,"book_ref":"Ch.1 First transition series definition p.4; The Electronic Configurations and Oxidation states, table + points 1-2, p.8","subtitle":"From Sc to Zn: the series where the 3d sublevel is filled successively","objectives":["Write the full and the [Ar] short electron configuration of Sc (Z = 21) to Zn (Z = 30).","Draw the 4s and 3d boxes using Hund's rule and count the unpaired electrons.","Know that Cr and Cu are different from the general pattern, and write their configurations as the book does."],"concept_ids":["te.electron-configuration"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"4s has only one orbital, and Ca already filled it with 2 electrons. An orbital can't hold more than 2."},{"id":"b","feedback":"Right: 4s is full at Ca, and the next sublevel in the filling order you studied is 3d. That is why this series is the one where the 3d sublevel is filled successively."},{"id":"c","feedback":"4p comes after 3d is full, so only after Zn (from Ga on). The filling order is 4s, then 3d, then 4p."}],"explanation":"Electron 21 goes into 3d. In the filling order 4s comes before 3d, and 4s is already full at Ca, so Sc is [Ar] $4s^2\\ 3d^1$."}},"s3":{"trap":{"statement":"Fe can be written as $[\\text{Ar}]\\ 3d^6$, without $4s^2$.","correction":"Count the electrons: $18 + 6 = 24$, not 26. In a neutral atom the electrons must add up to Z, so Fe keeps its $4s^2$: $[\\text{Ar}]\\ 4s^2\\ 3d^6$."}},"s4":{"fb":{"mistakes":[{"id":"m1","feedback":"$4s^1$ is only for Cr and Cu. Co follows the general pattern, so 4s is full."},{"id":"m2","feedback":"9 is everything after $[\\text{Ar}]$, but 4s takes its share first, so 3d gets fewer."},{"id":"m3","feedback":"You paired electrons too early. By Hund's rule, all 5 orbitals take one electron before any pairing."},{"id":"m4","feedback":"3d has only 5 orbitals. Electrons 6 and 7 must pair, so they are not unpaired."},{"id":"m5","feedback":"5 unpaired is Mn ($3d^5$). After Mn, each extra 3d electron makes a pair."}],"explanation":"$\\ce{_{27}Co}$: $[\\text{Ar}]\\ 4s^2\\ 3d^7$. 3d is $[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow][\\uparrow][\\uparrow]$: 3 unpaired electrons."},"hints":{"hints":["4s has only one orbital.","3d has 5 orbitals: fill them one at a time first.","7 electrons = 5 singly + 2 that make pairs."]}},"s6":{"trap":{"statement":"In Fe the 3d electrons can pair up while orbitals are still empty: $[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\ \\ ][\\ \\ ]$.","correction":"Pairing while orbitals are still empty breaks Hund's rule. Electrons repel each other, so they take the empty orbitals singly first."}},"s7":{"q":{"options":[{"id":"a","feedback":"The number of electrons is right, but they paired while the last orbital is still empty. That goes against Hund's rule: all 5 orbitals take one electron first."},{"id":"b","feedback":"Correct: $28 - 18 = 10$, two for 4s and 8 for 3d. The 8 = 5 singly + 3 pairs, so 2 unpaired electrons are left."},{"id":"c","feedback":"You put all 10 electrons in 3d and left 4s empty, as if the atom were $[\\text{Ar}]\\ 3d^{10}$. But Ni keeps the $4s^2$ that was filled at Ca."},{"id":"d","feedback":"This spreads the Cr and Cu exception ($4s^1$) to another element. In this series the book gives that exception for those two elements only, and Ni follows the general pattern."}],"explanation":"$\\ce{_{28}Ni}$: $[\\text{Ar}]\\ 4s^2\\ 3d^8$, so 2 unpaired electrons in 3d."},"hints":{"hints":["Start with $28 - 18$.","4s takes 2, like the rest of the series (except Cr and Cu).","3d: 5 singly first, the rest as pairs."]}},"s8":{"q":{"options":[{"id":"a","feedback":"This is missing $4s^2$: $18 + 3 = 21$, not 23. In a neutral atom the electrons must add up to Z."},{"id":"b","feedback":"The total is right (23), but 4s is empty. 4s was already filled at Ca, and 3d takes the rest."},{"id":"c","feedback":"Correct: $23 - 18 = 5$, two for 4s and 3 for 3d. That gives 3 unpaired electrons."},{"id":"d","feedback":"This spreads the Cr and Cu exception to V. The book gives it for those two only."}],"explanation":"General pattern $[\\text{Ar}]\\ 4s^2\\ 3d^{\\,Z-20}$: $23 - 20 = 3$."},"fb":{"mistakes":[{"id":"m1","feedback":"4s was already filled at Ca, so in Ti it is full, not empty."},{"id":"m2","feedback":"4 is all the electrons after $[\\text{Ar}]$, but 4s takes its share first, so 3d gets fewer."},{"id":"m3","feedback":"$4s^1$ is only for Cr and Cu. Ti follows the general pattern, like Ca."},{"id":"m4","feedback":"With 3 in 3d, the exponents add up to 23, but Ti needs 22."},{"id":"m5","feedback":"$3d^1$ is Sc (Z = 21). Ti has one electron more."}],"explanation":"$\\ce{_{22}Ti}$: $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6\\ 4s^2\\ 3d^2$, which is $[\\text{Ar}]\\ 4s^2\\ 3d^2$. Quick check: the exponents add up to 22."},"hints":{"hints":["Start with $22 - 18$.","4s takes 2, like Ca.","3d takes the rest. The exponents must add up to 22."]}},"s9":{"exam":{"body":"The five **3d orbitals** are filled **singly** up to Mn ($3d^5$), then **pairing** takes place up to Zn ($3d^{10}$): **Hund's rule**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ 4s فيه orbital واحد، والـ Ca ملاه خلاص بـ 2 electrons. والـ orbital مايشيلش أكتر من 2."},{"id":"b","feedback":"صح: الـ 4s اتملى عند الـ Ca، والـ sublevel اللي بعده في ترتيب الملء اللي درسته هو الـ 3d. وعشان كده السلسلة دي هي اللي الـ 3d sublevel بيتملي فيها بالتتابع."},{"id":"c","feedback":"الـ 4p دوره بييجي بعد ما الـ 3d يتملي، يعني بعد الـ Zn (من أول الـ Ga). ترتيب الملء: 4s وبعدين 3d وبعدين 4p."}],"explanation":"الـ electron رقم 21 بيروح الـ 3d. في ترتيب الملء الـ 4s قبل الـ 3d، والـ 4s اتملى خلاص عند الـ Ca، فالـ Sc بيبقى [Ar] $4s^2\\ 3d^1$."}},"s3":{"trap":{"statement":"الـ Fe ممكن يتكتب $[\\text{Ar}]\\ 3d^6$ من غير $4s^2$.","correction":"عدّ الـ electrons: $18 + 6 = 24$، مش 26. في الذرة المتعادلة الـ electrons لازم مجموعها يساوي Z، فالـ Fe محتفظ بالـ $4s^2$ بتاعه: $[\\text{Ar}]\\ 4s^2\\ 3d^6$."}},"s4":{"fb":{"mistakes":[{"id":"m1","feedback":"الـ $4s^1$ ده للـ Cr والـ Cu تحديدًا. الـ Co ماشي على القاعدة العامة، والـ 4s فيه مليان."},{"id":"m2","feedback":"الـ 9 دول هما مجموع الـ electrons اللي بعد الـ $[\\text{Ar}]$، والـ 4s بياخد نصيبه منهم الأول قبل الـ 3d."},{"id":"m3","feedback":"إنت عملت أزواج بدري. حسب الـ Hund's rule، الـ 5 orbitals كلهم بياخدوا electron واحد قبل أي أزواج."},{"id":"m4","feedback":"الـ 3d فيه 5 orbitals لا أكتر. الـ electron رقم 6 ورقم 7 لازم يعملوا أزواج، فمش unpaired."},{"id":"m5","feedback":"5 unpaired دي حالة الـ Mn ($3d^5$). بعد الـ Mn، أي electron زيادة في الـ 3d بيعمل زوج."}],"explanation":"$\\ce{_{27}Co}$: $[\\text{Ar}]\\ 4s^2\\ 3d^7$. الـ 3d شكله كده $[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow][\\uparrow][\\uparrow]$: يعني 3 unpaired electrons."},"hints":{"hints":["الـ 4s فيه orbital واحد.","الـ 3d فيه 5 orbitals: املاهم فرادى الأول.","الـ 7 electrons = 5 فرادى + 2 بيعملوا أزواج."]}},"s6":{"trap":{"statement":"في الـ Fe الـ 3d electrons ممكن يعملوا أزواج والـ orbitals لسه فيها فاضي: $[\\uparrow\\downarrow][\\uparrow\\downarrow][\\uparrow\\downarrow][\\ \\ ][\\ \\ ]$.","correction":"إنك تعمل أزواج والـ orbitals لسه فيها فاضي ده ضد الـ Hund's rule. الـ electrons بتتنافر مع بعض، فبتاخد الـ orbitals الفاضية فرادى الأول."}},"s7":{"q":{"options":[{"id":"a","feedback":"عدد الـ electrons صح، لكنهم عملوا أزواج والـ orbital الأخير لسه فاضي. ده ضد الـ Hund's rule: الـ 5 orbitals كلهم بياخدوا electron واحد الأول."},{"id":"b","feedback":"مظبوط: $28 - 18 = 10$، 2 للـ 4s و8 للـ 3d. والـ 8 دول = 5 فرادى + 3 أزواج، فيفضل 2 unpaired electrons."},{"id":"c","feedback":"إنت حطيت الـ 10 electrons كلهم في الـ 3d وسبت الـ 4s فاضي، كأن الذرة $[\\text{Ar}]\\ 3d^{10}$. لكن الـ Ni محتفظ بالـ $4s^2$ اللي اتملى عند الـ Ca."},{"id":"d","feedback":"كده إنت عمّمت استثناء الـ Cr والـ Cu ($4s^1$) على عنصر تاني. في السلسلة دي الكتاب بيدي الاستثناء ده للعنصرين دول تحديدًا، والـ Ni ماشي على القاعدة العامة."}],"explanation":"$\\ce{_{28}Ni}$: $[\\text{Ar}]\\ 4s^2\\ 3d^8$، يعني فيه 2 unpaired electrons في الـ 3d."},"hints":{"hints":["ابدأ بـ $28 - 18$.","الـ 4s بياخد 2، زي باقي السلسلة (ما عدا الـ Cr والـ Cu).","الـ 3d: 5 فرادى الأول، والباقي أزواج."]}},"s8":{"q":{"options":[{"id":"a","feedback":"كده ناقص $4s^2$: $18 + 3 = 21$، مش 23. في الذرة المتعادلة الـ electrons لازم مجموعها يساوي Z."},{"id":"b","feedback":"المجموع صح (23)، لكن الـ 4s فاضي. الـ 4s اتملى من عند الـ Ca، والـ 3d بياخد الباقي."},{"id":"c","feedback":"مظبوط: $23 - 18 = 5$، 2 للـ 4s و3 للـ 3d. وده بيدي 3 unpaired electrons."},{"id":"d","feedback":"كده إنت عمّمت استثناء الـ Cr والـ Cu على الـ V. الكتاب بيديه للعنصرين دول تحديدًا."}],"explanation":"القاعدة العامة هي $[\\text{Ar}]\\ 4s^2\\ 3d^{\\,Z-20}$: يعني $23 - 20 = 3$."},"fb":{"mistakes":[{"id":"m1","feedback":"الـ 4s اتملى خلاص عند الـ Ca، فمش ممكن يبقى فاضي في الـ Ti."},{"id":"m2","feedback":"الـ 4 دول هما مجموع الـ electrons اللي بعد الـ $[\\text{Ar}]$، والـ 4s بياخد نصيبه منهم الأول، فمش كلهم في الـ 3d."},{"id":"m3","feedback":"الـ $4s^1$ ده للـ Cr والـ Cu تحديدًا. الـ Ti ماشي على القاعدة العامة، زي الـ Ca."},{"id":"m4","feedback":"بالـ 3 دي الأُسس مجموعها 23، مش 22."},{"id":"m5","feedback":"الـ $3d^1$ ده الـ Sc (Z = 21). الـ Ti عنده electron زيادة."}],"explanation":"$\\ce{_{22}Ti}$: $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6\\ 4s^2\\ 3d^2$، وده هو نفسه $[\\text{Ar}]\\ 4s^2\\ 3d^2$. تشييك سريع: الأُسس مجموعها 22."},"hints":{"hints":["ابدأ بـ $22 - 18$.","الـ 4s بياخد 2، زي الـ Ca.","الـ 3d بياخد الباقي. والأُسس لازم مجموعها يطلع 22."]}},"s9":{"exam":{"body":"الـ 5 **3d orbitals** بيتملوا **فرادى** لحد الـ Mn ($3d^5$)، وبعدين بيبدأ الـ **pairing** لحد الـ Zn ($3d^{10}$): ده الـ **Hund's rule**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":1,"lesson_no":7,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-configuration","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Electronic configurations and oxidation states","duration_s":717.229,"start_s":26.7,"end_s":93.5,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.electron-configuration","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Electronic configuration of the first transition series","duration_s":51.12,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.cr-cu-anomaly","kind":"lesson","version":4,"catalog_version":3,"ord":172,"primary_concept_id":"te.cr-cu-anomaly","concepts":[{"concept_id":"te.cr-cu-anomaly","role":"primary"}],"title":"Abnormal electronic configuration of chromium and copper","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$[\\text{Ar}]\\ 4s^2\\ 3d^4$","correct":false},{"id":"b","text":"$[\\text{Ar}]\\ 4s^1\\ 3d^5$","correct":true},{"id":"c","text":"$[\\text{Ar}]\\ 4s^2\\ 3d^3\\ 4p^1$","correct":false}],"question":"Predict: how does the book write chromium?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Vanadium (Z = 23) is $[\\text{Ar}]\\ 4s^2\\ 3d^3$. Chromium (Z = 24) has one electron more."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"One electron more than vanadium"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"n":{"type":"Text","props":{"muted":true,"content":"In Cr, both 4s ($4s^1$) and 3d ($3d^5$) are half filled."},"children":[]},"t":{"type":"Text","props":{"content":"Compared with the pattern, 4s has one electron less and 3d one more. Now each of the five 3d orbitals holds one electron."},"children":[]},"b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":4}],"caption":"$4s^2\\ 3d^4$: one 3d orbital stays empty","show_unpaired":true},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":5}],"caption":"$\\ce{_{24}Cr}$: $[\\text{Ar}]\\ 4s^1\\ 3d^5$","show_unpaired":true},"children":[]},"c1":{"type":"Card","props":{"tone":"warning","title":"Expected pattern"},"children":["b1"]},"c2":{"type":"Card","props":{"tone":"success","title":"Real Cr (the book)"},"children":["b2"]},"kt":{"type":"KeyTerm","props":{"term_en":"Half-filled sublevel","definition":"A sublevel in which every orbital holds one electron, like $3d^5$ or $4s^1$."},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["cols","t","kt","n"]}}},"title":"Chromium: expected vs real"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"n":2},"elements":{"t":{"type":"Text","props":{"content":"Copper (Z = 29) has 11 electrons after $[\\text{Ar}]$. Put 2 or 1 of them in 4s, and the rest in 3d."},"children":[]},"b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":10}],"caption":"$4s^1\\ 3d^{10}$: every 3d orbital holds a pair","show_unpaired":true},"visible":{"eq":1,"$state":"/n"},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":9}],"caption":"$4s^2\\ 3d^9$ (the expected pattern): one 3d orbital has an unpaired electron","show_unpaired":true},"visible":{"eq":2,"$state":"/n"},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Filled sublevel","definition":"A sublevel in which every orbital holds two electrons, like $3d^{10}$."},"visible":{"eq":1,"$state":"/n"},"children":[]},"sl":{"type":"Slider","props":{"max":2,"min":1,"step":1,"label":"electrons in 4s","value":{"$bindState":"/n"}},"children":[]},"call":{"type":"Callout","props":{"variant":"tip"},"visible":{"eq":1,"$state":"/n"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","b2","b1","call","kt"]}}},"title":"Move one electron in copper"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Callout","props":{"variant":"info"},"children":[]},"t":{"type":"Text","props":{"content":"Why do Cr and Cu do this? The book gives one reason, in three links:"},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a"},{"to":"c","from":"b"}],"nodes":[{"id":"a","label":"3d half filled (d⁵) in Cr, or filled (d¹⁰) in Cu"},{"id":"b","label":"The atom has lower energy"},{"id":"c","label":"Extra stability"}],"layout":"vertical","caption":"Book p.9: why Cr and Cu are anomalous"},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Extra stability","definition":"The lower energy an atom has when its d sublevel is half filled ($d^5$) or filled ($d^{10}$)."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","fd","kt","c"]}}},"title":"The book's reason"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"q":{"type":"Classify","props":{"items":[{"id":"mn","text":"$\\ce{_{25}Mn}$: $[\\text{Ar}]\\ 4s^1\\ 3d^6$"},{"id":"co","text":"$\\ce{_{27}Co}$: $[\\text{Ar}]\\ 4s^2\\ 3d^7$"},{"id":"fe","text":"$\\ce{_{26}Fe}$: $[\\text{Ar}]\\ 4s^1\\ 3d^7$"},{"id":"cr","text":"$\\ce{_{24}Cr}$: $[\\text{Ar}]\\ 4s^2\\ 3d^4$"},{"id":"ni","text":"$\\ce{_{28}Ni}$: $[\\text{Ar}]\\ 3d^{10}$"},{"id":"cu","text":"$\\ce{_{29}Cu}$: $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$"}],"answer":{"ok":["co","cu"],"bad":["mn","fe","cr","ni"]},"prompt":"Sort each atom: is it written the way the book writes it?","categories":[{"id":"ok","label":"As the book writes it"},{"id":"bad","label":"Not correct"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","h"]}}},"title":"Which are written correctly?"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"Full configuration: $\\ce{_{24}Cr}$: $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6$ 4s___ 3d___ (type the exponents)","answers":[["1","one"],["5","five"]],"mistakes":[{"id":"m1","blank":0,"answer":"2"},{"id":"m2","blank":1,"answer":"4"},{"id":"m3","blank":0,"answer":"0"},{"id":"m4","blank":1,"answer":"6"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A filled d sublevel ($d^{10}$) gives the atom lower energy, so extra stability","correct":true},{"id":"b","text":"An s orbital can hold only one electron","correct":false},{"id":"c","text":"A half-filled d sublevel ($d^5$) gives extra stability","correct":false},{"id":"d","text":"Bigger atoms put more electrons in s","correct":false}],"question":"Silver ($\\ce{_{47}Ag}$) is below copper in group IB. Its outer sublevels are $5s^1\\ 4d^{10}$. Which reason fits?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","f"]}}},"title":"Silver, and Cr in full"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["$\\ce{_{24}Cr}$: $[\\text{Ar}]\\ 4s^1\\ 3d^5$: 4s and 3d are both half filled.","$\\ce{_{29}Cu}$: $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$: 4s is half filled, 3d is filled.","In the first series only Cr and Cu are anomalous."]},"children":[]},"bcr":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":5}],"caption":"$\\ce{_{24}Cr}$: $[\\text{Ar}]\\ 4s^1\\ 3d^5$","show_unpaired":true},"children":[]},"bcu":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":10}],"caption":"$\\ce{_{29}Cu}$: $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$","show_unpaired":true},"children":[]},"ccr":{"type":"Card","props":{"title":"Chromium: 3d half filled ($d^5$)"},"children":["bcr"]},"ccu":{"type":"Card","props":{"title":"Copper: 3d filled ($d^{10}$)"},"children":["bcu"]},"back":{"type":"Text","props":{"content":"Back to the hook: Cr is $4s^1\\ 3d^5$ because a half-filled 3d lowers the atom's energy."},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["ccr","ccu"]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["cols","b","exam","back","self"]},"self":{"type":"Text","props":{"content":"Can you explain why copper ends with $4s^1\\ 3d^{10}$ and not $4s^2\\ 3d^9$?"},"children":[]}}},"title":"Summary"}],"title":"Abnormal electronic configuration of chromium and copper","minutes":7,"book_ref":"Ch.1 The Electronic Configurations and Oxidation states, point 2, pp.8-9; coinage metals, p.10","subtitle":"Why Cr and Cu break the pattern","objectives":["Write the configurations of Cr (Z = 24) and Cu (Z = 29) as the book writes them.","Give the book's reason: the atom has lower energy (extra stability) when d is half filled ($d^5$) or filled ($d^{10}$).","Recognize that in the first transition series only Cr and Cu are anomalous."],"concept_ids":["te.cr-cu-anomaly"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"That is what the general pattern predicts, but the book writes the real Cr atom differently: here 4s does not keep two electrons."},{"id":"b","feedback":"Yes, the real Cr atom has only one 4s electron. This lesson explains why."},{"id":"c","feedback":"4p starts filling only after 3d is full, from Ga on, so chromium's extra electron is not in 4p."}],"explanation":"By the general pattern Cr would be $[\\text{Ar}]\\ 4s^2\\ 3d^4$, but the book writes $[\\text{Ar}]\\ 4s^1\\ 3d^5$: one electron sits in 3d instead of 4s, so 3d is half filled."}},"s3":{"call":{"body":"$\\ce{_{29}Cu}$: $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$. Here 4s is half filled, but 3d is filled ($d^{10}$).","title":"This is the real copper atom"}},"s4":{"c":{"body":"This is not the only main factor that causes the stability of the atom.","title":"The book adds"}},"s5":{"h":{"hints":["Only two atoms of this series are anomalous.","An atom moves to $4s^1$ only if 3d then becomes half filled or filled.","Check each 3d count: is it 5, 10, or neither?"]},"q":{"items":[{"id":"mn","feedback":"Mn follows the pattern, $[\\text{Ar}]\\ 4s^2\\ 3d^5$: its 3d is already half filled with $4s^2$, so it is not written $4s^1\\ 3d^6$."},{"id":"co","feedback":"Co is neither Cr nor Cu, and this version follows the pattern $4s^2\\ 3d^{Z-20}$, so it is written correctly."},{"id":"fe","feedback":"With $4s^1$, Fe's 3d would hold 7 electrons, which is neither half filled nor filled, so Fe keeps $4s^2\\ 3d^6$."},{"id":"cr","feedback":"In this version one 3d orbital is still empty; the book writes Cr with one electron in each of the five 3d orbitals."},{"id":"ni","feedback":"The book shows no atom of this series with an empty 4s; Ni follows the pattern, $[\\text{Ar}]\\ 4s^2\\ 3d^8$."},{"id":"cu","feedback":"This version has a filled 3d ($3d^{10}$), which is how the book writes copper."}],"explanation":"Only Cr and Cu are anomalous in this series: Cr $[\\text{Ar}]\\ 4s^1\\ 3d^5$, Cu $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$. Mn, Fe, Co and Ni follow $[\\text{Ar}]\\ 4s^2\\ 3d^{Z-20}$."}},"s6":{"f":{"mistakes":[{"id":"m1","feedback":"$4s^2$ is the expected pattern, but the real Cr atom has one 4s electron."},{"id":"m2","feedback":"With $3d^4$ one 3d orbital stays empty, so 3d would not be half filled."},{"id":"m3","feedback":"An empty 4s would mean both 4s electrons moved to 3d; chromium moves one, which is enough to half fill 3d."},{"id":"m4","feedback":"With $3d^6$, 3d is not half filled, and the exponents no longer add up to 24."}],"explanation":"$\\ce{_{24}Cr}$: $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6\\ 4s^1\\ 3d^5$: both 4s and 3d are half filled."},"q":{"options":[{"id":"a","feedback":"Right. It is the same reason as for copper: a filled d sublevel lowers the atom's energy."},{"id":"b","feedback":"An s orbital holds up to two electrons, like $4s^2$ in Zn, so the s sublevel is not the reason."},{"id":"c","feedback":"$4d^{10}$ is not half filled: it has a pair in every orbital, so the book calls it filled."},{"id":"d","feedback":"Atom size is not the book's reason for these configurations."}],"explanation":"Book p.10 lists Cu ($4s^1\\ 3d^{10}$), Ag ($5s^1\\ 4d^{10}$) and Au ($6s^1\\ 5d^{10}$): each has a filled d sublevel."}},"s7":{"exam":{"body":"Because the atom has **lower energy** (**extra stability**) when d is half filled ($d^5$), as in Cr, or filled ($d^{10}$), as in Cu.","title":"Give reasons: the abnormal configuration of Cr and Cu"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"ده اللي القاعدة العامة بتتوقعه، لكن الكتاب بيكتب ذرة الـ Cr الحقيقية بشكل تاني: هنا الـ 4s مابيحتفظش بـ 2 electrons."},{"id":"b","feedback":"أيوه، ذرة الـ Cr الحقيقية فيها electron واحد بس في الـ 4s. الدرس ده هيشرح ليه."},{"id":"c","feedback":"الـ 4p مابيبدأش يتملي غير بعد ما الـ 3d يتملي، من أول الـ Ga، فالـ electron الزيادة بتاع الـ chromium مش في الـ 4p."}],"explanation":"على القاعدة العامة الـ Cr كان هيبقى $[\\text{Ar}]\\ 4s^2\\ 3d^4$، لكن الكتاب بيكتبه $[\\text{Ar}]\\ 4s^1\\ 3d^5$: electron واحد بيبقى في الـ 3d بدل الـ 4s، فالـ 3d بيبقى half filled."}},"s3":{"call":{"body":"$\\ce{_{29}Cu}$: $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$. هنا الـ 4s بيبقى half filled، لكن الـ 3d بيبقى filled ($d^{10}$).","title":"دي ذرة الـ copper الحقيقية"}},"s4":{"c":{"body":"ده مش العامل الأساسي الوحيد اللي بيدّي الذرة stability.","title":"الكتاب بيضيف"}},"s5":{"h":{"hints":["في السلسلة دي فيه ذرّتين تحديدًا هما اللي abnormal.","الذرة مابتروحش لـ $4s^1$ غير لو الـ 3d هيبقى كده half filled أو filled.","راجع عدد الـ 3d في كل واحدة: 5 ولا 10 ولا لا ده ولا ده؟"]},"q":{"items":[{"id":"mn","feedback":"الـ Mn ماشي على القاعدة العامة، $[\\text{Ar}]\\ 4s^2\\ 3d^5$: الـ 3d بتاعه half filled أصلًا ومعاه $4s^2$، فمابيتكتبش $4s^1\\ 3d^6$."},{"id":"co","feedback":"الـ Co لا هو Cr ولا Cu، والشكل ده ماشي على $4s^2\\ 3d^{Z-20}$، فهو مكتوب صح."},{"id":"fe","feedback":"مع $4s^1$، الـ 3d بتاع الـ Fe هيشيل 7 electrons، وده لا half filled ولا filled، فالـ Fe بيفضل $4s^2\\ 3d^6$."},{"id":"cr","feedback":"في الشكل ده فيه 3d orbital لسه فاضي؛ الكتاب بيكتب الـ Cr بـ electron واحد في كل واحد من الخمس 3d orbitals."},{"id":"ni","feedback":"الكتاب مابيورّيش أي ذرة في السلسلة دي والـ 4s بتاعها فاضي؛ الـ Ni ماشي على القاعدة العامة، $[\\text{Ar}]\\ 4s^2\\ 3d^8$."},{"id":"cu","feedback":"الشكل ده فيه 3d filled ($3d^{10}$)، وده بالظبط اللي الكتاب بيكتب بيه الـ copper."}],"explanation":"في السلسلة دي مفيش غير الـ Cr والـ Cu اللي abnormal: الـ Cr $[\\text{Ar}]\\ 4s^1\\ 3d^5$، والـ Cu $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$. أما الـ Mn والـ Fe والـ Co والـ Ni فماشيين على $[\\text{Ar}]\\ 4s^2\\ 3d^{Z-20}$."}},"s6":{"f":{"mistakes":[{"id":"m1","feedback":"الـ $4s^2$ ده توزيع القاعدة العامة، لكن ذرة الـ Cr الحقيقية فيها electron واحد في الـ 4s."},{"id":"m2","feedback":"مع $3d^4$ فيه 3d orbital بيفضل فاضي، فالـ 3d مش هيبقى half filled."},{"id":"m3","feedback":"لو الـ 4s فاضي يبقى الـ 2 electrons بتوعه راحوا للـ 3d؛ الـ Cr بينقل واحد، وده كفاية إن الـ 3d يبقى half filled."},{"id":"m4","feedback":"مع $3d^6$، الـ 3d مش half filled، ومجموع الأُسس مش هيبقى 24."}],"explanation":"$\\ce{_{24}Cr}$: $1s^2\\ 2s^2\\ 2p^6\\ 3s^2\\ 3p^6\\ 4s^1\\ 3d^5$: الـ 4s والـ 3d الاتنين half filled."},"q":{"options":[{"id":"a","feedback":"صح. نفس السبب بتاع الـ copper بالظبط: الـ d sublevel لما يبقى filled بيقلّل طاقة الذرة."},{"id":"b","feedback":"الـ s orbital بيشيل لحد 2 electrons، زي الـ $4s^2$ في الـ Zn، فالـ s sublevel مش هو السبب."},{"id":"c","feedback":"الـ $4d^{10}$ مش half filled: فيه زوج في كل orbital، فالكتاب بيسمّيه filled."},{"id":"d","feedback":"حجم الذرة مش هو السبب اللي في الكتاب للتوزيعات دي."}],"explanation":"الكتاب في صفحة 10 بيذكر الـ Cu ($4s^1\\ 3d^{10}$) والـ Ag ($5s^1\\ 4d^{10}$) والـ Au ($6s^1\\ 5d^{10}$): كل واحد فيهم عنده d sublevel مليان (filled)."}},"s7":{"exam":{"body":"عشان الذرة بيبقى عندها **energy أقل** (**extra stability**) لما الـ d يبقى half filled ($d^5$) زي الـ Cr، أو filled ($d^{10}$) زي الـ Cu.","title":"علّل: التوزيع الـ abnormal للـ Cr والـ Cu"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":2,"lesson_no":8,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-configuration","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Electronic configurations and oxidation states","duration_s":717.229,"start_s":101.3,"end_s":172,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.cr-cu-anomaly","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Abnormal electronic configuration of chromium and copper","duration_s":50.04,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"1","relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.ions","kind":"lesson","version":2,"catalog_version":3,"ord":174,"primary_concept_id":"chem.ions","concepts":[{"concept_id":"chem.ions","role":"primary"}],"title":"Ions (cations and anions)","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"24","correct":true},{"id":"b","text":"28","correct":false},{"id":"c","text":"26","correct":false}],"question":"Predict: an iron atom has 26 protons and 26 electrons. How many electrons does $\\ce{Fe^{2+}}$ have?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Chapter 1 writes iron as $\\ce{Fe^{2+}}$ and $\\ce{Fe^{3+}}$. What does the small charge mean?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"What does the 2+ mean?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"r":{"type":"Text","props":{"muted":true,"content":"Remember: a neutral atom has equal numbers of protons (+) and electrons (−)."},"children":[]},"t":{"type":"Text","props":{"content":"When an ion forms, only electrons move. The protons stay the same, so it is still the same element."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a","label":"loses 1 electron"}],"nodes":[{"id":"a","label":"Na atom: 11 protons, 11 electrons"},{"id":"b","label":"Na⁺ ion: 11 protons, 10 electrons"}],"caption":"Sodium forms a positive ion"},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Ion","definition":"An atom, or a group of atoms, that carries an electric charge because it lost or gained electrons."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["r","kt","fd","t"]}}},"title":"Ion"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"l":0},"elements":{"c":{"type":"Stat","props":{"tone":"warning","label":"positive charge","value":{"args":{"l":{"$state":"/l"},"expr":"l","digits":0},"$computed":"calc"}},"children":[]},"e":{"type":"Stat","props":{"tone":"info","label":"electrons","value":{"args":{"l":{"$state":"/l"},"expr":"26 - l","digits":0},"$computed":"calc"}},"children":[]},"p":{"type":"Stat","props":{"tone":"neutral","label":"protons","value":26},"children":[]},"t":{"type":"Text","props":{"content":"Take electrons away from an iron atom (Z = 26). 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Its charge equals the number of electrons the atom gained."},"children":[]},"k1t":{"type":"Text","props":{"content":"$\\ce{Cl-}$: 17 protons, 18 electrons"},"children":[]},"k2t":{"type":"Text","props":{"content":"$\\ce{O^{2-}}$: 8 protons, 10 electrons"},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["k1","k2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","kt","cols","fd","n"]}}},"title":"Anion"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"$\\ce{_{29}Cu^{2+}}$ has ___ electrons.","answers":[["27","twenty-seven","twenty seven"]],"mistakes":[{"id":"m1","blank":0,"answer":"31"},{"id":"m2","blank":0,"answer":"29"},{"id":"m3","blank":0,"answer":"2"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{Mn^{2+}}$","correct":true},{"id":"b","text":"$\\ce{V^{2+}}$","correct":false},{"id":"c","text":"$\\ce{Mn^{2-}}$","correct":false},{"id":"d","text":"a neutral Mn atom","correct":false}],"question":"A particle has 25 protons and 23 electrons. What is it? (Mn: Z = 25, V: Z = 23)"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","q"]}}},"title":"Count the electrons"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["An ion forms when an atom loses or gains electrons. Its protons do not change.","Cation: positive, electrons lost (e.g. $\\ce{Fe^{3+}}$). Anion: negative, electrons gained (e.g. $\\ce{Cl-}$).","Electrons in a cation = Z − charge: $\\ce{Fe^{2+}}$ has 26 − 2 = 24."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_t"]},"next":{"type":"Text","props":{"muted":true,"content":"Next: which electrons does iron lose first, 4s or 3d? That is the next lesson."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","next","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why Fe and $\\ce{Fe^{3+}}$ are the same element, though their electrons differ?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"Fe and $\\ce{Fe^{3+}}$ both have 26 protons. When an ion forms, only electrons move; the protons stay the same, so it is still the same element."},"children":[]}}},"title":"Summary"}],"title":"Ions (cations and anions)","minutes":5,"book_ref":"Background for Ch.1 point 3, p.9 (ions such as Fe²⁺ and Fe³⁺)","subtitle":"What the small charge on Fe²⁺ means","objectives":["State that an ion forms when an atom loses or gains electrons, while its protons stay the same.","Tell a positive ion (cation) from a negative ion (anion).","Find the number of electrons in an ion from Z and its charge, e.g. $\\ce{Fe^{2+}}$."],"concept_ids":["chem.ions"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Yes: 26 protons and 24 electrons leave two extra positive charges."},{"id":"b","feedback":"Two more electrons add two negative charges, so the particle would not be positive."},{"id":"c","feedback":"26 and 26 cancel out, so the charge would be zero, not 2+."}],"explanation":"$\\ce{Fe^{2+}}$ has 24 electrons: the atom loses 2 electrons while its 26 protons stay the same, so 26 positive charges against 24 negative ones leave a charge of 2+."}},"s3":{"c2":{"body":"26 protons and 24 electrons: this is $\\ce{Fe^{2+}}$.","title":"Iron (II) ion"},"c3":{"body":"26 protons and 23 electrons: this is $\\ce{Fe^{3+}}$.","title":"Iron (III) ion"}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"A 2+ charge means electrons were lost, not gained, so the count goes down."},{"id":"m2","feedback":"29 is the neutral atom; the 2+ means electrons were lost."},{"id":"m3","feedback":"2 is the charge, not the electron count, which starts from Z = 29."}],"explanation":"Cu has 29 electrons; losing 2 leaves 27. Protons stay 29."},"q":{"options":[{"id":"a","feedback":"Right: 25 protons make it Mn, and two missing electrons give 2+."},{"id":"b","feedback":"23 is the electron count, and protons, not electrons, decide the element: here there are 25."},{"id":"c","feedback":"Fewer electrons than protons leaves extra positive charge, so the sign is +, not −."},{"id":"d","feedback":"A neutral atom has equal numbers of protons and electrons, and 25 and 23 are not equal."}],"explanation":"Protons (25) fix the element: Mn. Charge = 25 − 23 = +2."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"أيوه: 26 protons و 24 electrons، يعني فاضل 2 positive charges زيادة."},{"id":"b","feedback":"2 electrons زيادة يعني 2 negative charges زيادة، فالـ particle مش هتبقى positive."},{"id":"c","feedback":"26 و 26 بيلغوا بعض، يعني الـ charge هتبقى صفر، مش 2+."}],"explanation":"الـ $\\ce{Fe^{2+}}$ فيه 24 electrons: الذرة بتفقد 2 electrons والـ 26 protons بتوعها زي ما هم، فـ 26 positive charges قصاد 24 negative charges بيسيبوا charge قيمتها 2+."}},"s3":{"c2":{"body":"26 protons و 24 electrons: ده كده $\\ce{Fe^{2+}}$.","title":"الـ Iron (II) ion"},"c3":{"body":"26 protons و 23 electrons: ده كده $\\ce{Fe^{3+}}$.","title":"الـ Iron (III) ion"}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"الـ 2+ charge معناها إن فيه electrons اتفقدت، مش اتكسبت، فالعدد بيقل."},{"id":"m2","feedback":"29 دي عدد الـ electrons في الذرة المتعادلة، والـ 2+ معناها إن فيه electrons اتفقدت."},{"id":"m3","feedback":"2 دي الـ charge، مش عدد الـ electrons. ابدأ من Z = 29."}],"explanation":"الـ Cu فيه 29 electrons؛ لما يفقد 2 بيفضل 27. والـ protons بتفضل 29."},"q":{"options":[{"id":"a","feedback":"صح: الـ 25 protons بيخلّوه Mn، والـ 2 electrons الناقصين بيدّوا 2+."},{"id":"b","feedback":"23 ده عدد الـ electrons، واللي بيحدد العنصر هو الـ protons، مش الـ electrons: وعددهم هنا 25."},{"id":"c","feedback":"لما الـ electrons تبقى أقل من الـ protons، بيفضل positive charge زيادة، فالإشارة +، مش −."},{"id":"d","feedback":"الذرة المتعادلة عدد الـ protons فيها بيساوي عدد الـ electrons، و 25 و 23 مش متساويين."}],"explanation":"الـ protons (25) هي اللي بتحدد العنصر: Mn. والـ charge = 25 − 23 = +2."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":2,"is_basics":true,"lesson_no":2,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-chem.ions","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Ions (cations and anions): from zero","duration_s":332.08,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.ions","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Ions (cations and anions)","duration_s":49.6,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.ion-configuration","kind":"lesson","version":2,"catalog_version":3,"ord":176,"primary_concept_id":"te.ion-configuration","concepts":[{"concept_id":"te.ion-configuration","role":"primary"}],"title":"Ions: 4s electrons are lost first","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The two 4s electrons","correct":true},{"id":"b","text":"Two 3d electrons, because 3d was filled last","correct":false},{"id":"c","text":"One 4s electron and one 3d electron","correct":false}],"question":"Predict: which two electrons leave?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Iron is $[\\text{Ar}]\\ 4s^2\\ 3d^6$. To form $\\ce{Fe^{2+}}$, it loses two electrons."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Which electrons leave first?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 360 260\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"120\" cy=\"130\" r=\"30\" fill=\"none\" stroke=\"#94a3b8\" stroke-opacity=\"0.5\" stroke-width=\"1.5\"/><circle cx=\"120\" cy=\"130\" r=\"54\" fill=\"none\" stroke=\"#94a3b8\" stroke-opacity=\"0.5\" stroke-width=\"1.5\"/><circle cx=\"120\" cy=\"130\" r=\"80\" fill=\"none\" stroke=\"#60a5fa\" stroke-opacity=\"1\" stroke-width=\"2.5\"/><circle cx=\"120\" cy=\"130\" r=\"108\" fill=\"none\" stroke=\"#fbbf24\" stroke-opacity=\"1\" stroke-width=\"2.5\"/><circle cx=\"120\" cy=\"130\" r=\"9\" fill=\"#f87171\"/><circle cx=\"44.8\" cy=\"102.6\" r=\"5.5\" fill=\"#60a5fa\"/><circle cx=\"66.5\" cy=\"70.5\" r=\"5.5\" fill=\"#60a5fa\"/><circle cx=\"100.6\" cy=\"52.4\" r=\"5.5\" fill=\"#60a5fa\"/><circle cx=\"139.4\" cy=\"52.4\" r=\"5.5\" fill=\"#60a5fa\"/><circle cx=\"173.5\" cy=\"70.5\" r=\"5.5\" fill=\"#60a5fa\"/><circle cx=\"195.2\" cy=\"102.6\" r=\"5.5\" fill=\"#60a5fa\"/><circle cx=\"208.5\" cy=\"68.1\" r=\"6.5\" fill=\"#fbbf24\"/><line x1=\"215.8\" y1=\"62.9\" x2=\"241.2\" y2=\"45.1\" stroke=\"#fbbf24\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"241.2,45.1 237.3,52.1 233.3,46.4\" fill=\"#fbbf24\"/><circle cx=\"208.5\" cy=\"191.9\" r=\"6.5\" fill=\"#fbbf24\"/><line x1=\"215.8\" y1=\"197.1\" x2=\"241.2\" y2=\"214.9\" stroke=\"#fbbf24\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"241.2,214.9 233.3,213.6 237.3,207.9\" fill=\"#fbbf24\"/><text x=\"262\" y=\"40\" font-size=\"14\" fill=\"#fbbf24\">4s electrons</text><text x=\"262\" y=\"58\" font-size=\"14\" fill=\"#fbbf24\">n = 4: lost first</text><text x=\"262\" y=\"214\" font-size=\"14\" fill=\"#60a5fa\">3d electrons</text><text x=\"262\" y=\"232\" font-size=\"14\" fill=\"#60a5fa\">n = 3: stay</text><text x=\"120\" y=\"156\" text-anchor=\"middle\" font-size=\"11\" fill=\"#94a3b8\">nucleus</text></svg>","caption":"Fe: 4s is in level n = 4, 3d is in level n = 3","max_width":380},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t1":{"type":"Text","props":{"content":"In Fe, the 4s electrons are in the outermost level (n = 4). The 3d electrons are in n = 3, nearer the nucleus."},"children":[]},"t2":{"type":"Text","props":{"content":"So a first-series atom loses its 4s electrons first. For higher charges, 3d electrons then leave one by one."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","t1","t2","m"]}}},"title":"4s is in the outermost level"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"$\\ce{_{27}Co}$ is $[\\text{Ar}]\\ 4s^2\\ 3d^7$. So $\\ce{Co^{2+}}$ = [Ar] 4s___ 3d___","answers":[["0","zero"],["7","seven"]],"mistakes":[{"id":"m1","blank":1,"answer":"5"},{"id":"m2","blank":0,"answer":"2"},{"id":"m3","blank":1,"answer":"9"},{"id":"m4","blank":0,"answer":"1"}]},"children":[]},"h":{"type":"Heading","props":{"text":"Your turn: Co²⁺ (Z = 27)","level":3},"children":[]},"hl":{"type":"HintLadder","props":{},"children":[]},"r1":{"type":"Reveal","props":{"label":"Step 1: Write the atom"},"children":["r1f"]},"r2":{"type":"Reveal","props":{"label":"Step 2: Remove the 4s electrons first"},"children":["r2f","r2b","r2t"]},"r1f":{"type":"Formula","props":{"latex":"\\ce{_{26}Fe}:\\ [\\text{Ar}]\\ 4s^2\\ 3d^6"},"children":[]},"r2b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":6}],"caption":"4s is empty; 3d keeps its 6 electrons","show_unpaired":true},"children":[]},"r2f":{"type":"Formula","props":{"latex":"\\ce{Fe^{2+}}:\\ [\\text{Ar}]\\ 3d^6"},"children":[]},"r2t":{"type":"Text","props":{"content":"Check: 18 + 6 = 24 electrons = 26 − 2."},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["r1","r2","h","f","hl"]}}},"title":"Worked: Fe²⁺, then your turn: Co²⁺"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"k":0},"elements":{"t":{"type":"Text","props":{"content":"Vanadium is $[\\text{Ar}]\\ 4s^2\\ 3d^3$. Remove its electrons one at a time. Which sublevel empties first?"},"children":[]},"rv":{"type":"Reveal","props":{"label":"Tried all five? Tap to see the pattern"},"children":["obs"]},"sl":{"type":"Slider","props":{"max":5,"min":0,"step":1,"label":"electrons removed","value":{"$bindState":"/k"}},"children":[]},"v0":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":3}],"caption":"$\\ce{V}$: $4s^2\\ 3d^3$ (the atom)","show_unpaired":true},"visible":{"eq":0,"$state":"/k"},"children":[]},"v1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":3}],"caption":"$\\ce{V+}$: $4s^1\\ 3d^3$","show_unpaired":true},"visible":{"eq":1,"$state":"/k"},"children":[]},"v2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":3}],"caption":"$\\ce{V^{2+}}$: $4s^0\\ 3d^3$: 4s is empty","show_unpaired":true},"visible":{"eq":2,"$state":"/k"},"children":[]},"v3":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":2}],"caption":"$\\ce{V^{3+}}$: $4s^0\\ 3d^2$","show_unpaired":true},"visible":{"eq":3,"$state":"/k"},"children":[]},"v4":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":1}],"caption":"$\\ce{V^{4+}}$: $4s^0\\ 3d^1$","show_unpaired":true},"visible":{"eq":4,"$state":"/k"},"children":[]},"v5":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":0}],"caption":"$\\ce{V^{5+}}$: $4s^0\\ 3d^0$","show_unpaired":true},"visible":{"eq":5,"$state":"/k"},"children":[]},"obs":{"type":"BulletList","props":{"items":["4s empties first: V to $\\ce{V^{2+}}$.","Then 3d electrons leave one by one: $\\ce{V^{3+}}$ to $\\ce{V^{5+}}$.","The book shows the same chain for vanadium on p.10."]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","v0","v1","v2","v3","v4","v5","rv"]}}},"title":"Strip a vanadium atom"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"An ion $\\ce{X^{3+}}$ is $[\\text{Ar}]\\ 3d^3$. It has ___ electrons, so the atom X has Z = ___.","answers":[["21","twenty-one","twenty one"],["24","twenty-four","twenty four"]],"mistakes":[{"id":"m1","blank":0,"answer":"3"},{"id":"m2","blank":0,"answer":"18"},{"id":"m3","blank":1,"answer":"18"},{"id":"m4","blank":1,"answer":"21"},{"id":"m5","blank":1,"answer":"27"}]},"children":[]},"h":{"type":"HintLadder","props":{},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$[\\text{Ar}]\\ 4s^2\\ 3d^6$","correct":false},{"id":"b","text":"$[\\text{Ar}]\\ 3d^8$","correct":true},{"id":"c","text":"$[\\text{Ar}]\\ 4s^1\\ 3d^7$","correct":false},{"id":"d","text":"$[\\text{Ar}]\\ 4s^2\\ 3d^8$","correct":false}],"question":"Which is the configuration of $\\ce{_{28}Ni^{2+}}$? (Ni: $[\\text{Ar}]\\ 4s^2\\ 3d^8$)"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","f","h"]}}},"title":"Ni²⁺ and a mystery ion"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":4}],"caption":"$\\ce{Cr^{2+}}$: the 4s electron and one 3d electron are gone","show_unpaired":true},"children":[]},"f":{"type":"Formula","props":{"latex":"\\ce{_{24}Cr}:\\ [\\text{Ar}]\\ 4s^1\\ 3d^5 \\;\\longrightarrow\\; \\ce{Cr^{2+}}:\\ [\\text{Ar}]\\ 3d^4"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Cr and Cu atoms have only one 4s electron. So for a 2+ ion, the second electron must come from 3d."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","f","b","m"]}}},"title":"Cr and Cu ions"},{"id":"s7","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Book point 3: all elements of the first series have oxidation state (+2) after losing their 4s electrons, except scandium."},"children":[]},"k1":{"type":"Card","props":{"tone":"warning","title":"Scandium"},"children":["k1t","k1b"]},"k2":{"type":"Card","props":{"tone":"info","title":"Zinc"},"children":["k2t","k2b"]},"kt":{"type":"KeyTerm","props":{"term_en":"Oxidation state","definition":"For a simple metal ion like $\\ce{Fe^{2+}}$, it equals the ion's charge (+2). The next lesson explains it fully."},"children":[]},"k1b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":0}],"caption":"$\\ce{Sc^{3+}}$: $[\\text{Ar}]$, 4s and 3d are empty","show_unpaired":true},"children":[]},"k1t":{"type":"Text","props":{"content":"$\\ce{_{21}Sc}$: $[\\text{Ar}]\\ 4s^2\\ 3d^1$. The book's table gives Sc only +3: $\\ce{Sc^{3+}}$ is $[\\text{Ar}]$."},"children":[]},"k2b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":10}],"caption":"$\\ce{Zn^{2+}}$: $[\\text{Ar}]\\ 3d^{10}$","show_unpaired":true},"children":[]},"k2t":{"type":"Text","props":{"content":"$\\ce{_{30}Zn}$ loses its two 4s electrons: $\\ce{Zn^{2+}}$ is $[\\text{Ar}]\\ 3d^{10}$, oxidation state +2."},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["k1","k2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","kt","cols"]}}},"title":"+2 for all, except scandium"},{"id":"s8","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$[\\text{Ar}]\\ 4s^1\\ 3d^8$","correct":false},{"id":"b","text":"$[\\text{Ar}]\\ 3d^9$","correct":true},{"id":"c","text":"$[\\text{Ar}]\\ 4s^2\\ 3d^7$","correct":false},{"id":"d","text":"$[\\text{Ar}]\\ 3d^{10}$","correct":false}],"question":"Which is the configuration of $\\ce{Cu^{2+}}$? ($\\ce{_{29}Cu}$: $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$)"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Titanium ($\\ce{_{22}Ti}$), like scandium, has no +2 oxidation state."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Copper, titanium"},{"id":"s9","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["A first-series atom loses its 4s electrons first: 4s is in the outermost level (n = 4).","Cr and Cu have only $4s^1$, so their 2+ ions also lose one 3d electron: $\\ce{Cr^{2+}}$ is $[\\text{Ar}]\\ 3d^4$.","All have oxidation state (+2), except Sc (only +3)."]},"children":[]},"ans":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Why Mn²⁺ is [Ar] 3d⁵"}},"children":["ans_t","ans_b"]},"back":{"type":"Text","props":{"content":"Back to the hook: Fe loses its two 4s electrons, so $\\ce{Fe^{2+}}$ is $[\\text{Ar}]\\ 3d^6$."},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Exam wording"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","back","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why $\\ce{Mn^{2+}}$ is $[\\text{Ar}]\\ 3d^5$ and not $[\\text{Ar}]\\ 4s^2\\ 3d^3$?"},"children":[]},"ans_b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":5}],"caption":"$\\ce{Mn^{2+}}$: 4s is empty; 3d keeps its 5 electrons","show_unpaired":true},"children":[]},"ans_t":{"type":"Text","props":{"content":"Mn is $[\\text{Ar}]\\ 4s^2\\ 3d^5$. Its 4s electrons are in the outermost level (n = 4), so they leave first and 3d keeps its 5 electrons: $\\ce{Mn^{2+}}$ is $[\\text{Ar}]\\ 3d^5$. Removing two 3d electrons instead would give $[\\text{Ar}]\\ 4s^2\\ 3d^3$."},"children":[]}}},"title":"Summary"}],"title":"Ions: 4s electrons are lost first","minutes":9,"book_ref":"Ch.1 The Electronic Configurations and Oxidation states, point 3, p.9; vanadium ions figure, p.10","subtitle":"Which electrons leave when a transition metal forms an ion","objectives":["Write the configuration of a first-series positive ion: remove the 4s electrons first, then 3d electrons one by one.","Explain why: 4s is in the outermost level (n = 4).","Handle Cr and Cu ions, and identify an element from its ion's configuration.","State that all elements of the series have oxidation state (+2), except scandium."],"concept_ids":["te.ion-configuration"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Yes. The 4s electrons are in the outermost level, so they leave first."},{"id":"b","feedback":"That is the 'last in, first out' idea, but electrons do not leave in reverse filling order: they leave from the sublevel farther from the nucleus first."},{"id":"c","feedback":"There is no reason to take one from each: electrons leave from the outermost level first."}],"explanation":"The two 4s electrons leave, because 4s is the outermost level. So $\\ce{Fe^{2+}}$ is $[\\text{Ar}]\\ 3d^6$."}},"s2":{"m":{"statement":"$\\ce{Fe^{2+}}$ is $[\\text{Ar}]\\ 4s^2\\ 3d^4$: the electrons that went in last come out first.","correction":"4s fills before 3d, but 4s is in the outermost level, so it empties first. $\\ce{Fe^{2+}}$ is $[\\text{Ar}]\\ 3d^6$."}},"s3":{"f":{"mistakes":[{"id":"m1","feedback":"You removed 3d electrons, but 4s is the outermost level, so its electrons leave first."},{"id":"m2","feedback":"4s is still full here, but the 4s electrons are the ones that leave first."},{"id":"m3","feedback":"The 4s electrons leave the atom; they do not move into 3d."},{"id":"m4","feedback":"The ion lost two electrons, and both came from 4s, which held two."}],"explanation":"$\\ce{Co^{2+}}$: $[\\text{Ar}]\\ 4s^0\\ 3d^7$, written $[\\text{Ar}]\\ 3d^7$. Check: 18 + 7 = 25 = 27 − 2."},"hl":{"hints":["The charge is 2+, so 2 electrons leave.","They leave from the outermost level first.","4s holds 2 electrons; 3d is not touched."]}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"That is just the 3d count; the 18 electrons of [Ar] count too."},{"id":"m2","feedback":"You counted just [Ar]; the 3d electrons count too."},{"id":"m3","feedback":"[Ar] alone is not the atom: the atom also has the 3d electrons and the 3 electrons the ion lost."},{"id":"m4","feedback":"Z belongs to the neutral atom, and a 3+ ion has 3 fewer electrons than its atom."},{"id":"m5","feedback":"A 3+ ion lost three electrons, so they are added back once to the ion's count, not twice."}],"explanation":"18 + 3 = 21 electrons. X lost 3, so Z = 21 + 3 = 24: X is Cr, and the ion is $\\ce{Cr^{3+}}$."},"h":{"hints":["[Ar] stands for 18 electrons.","A 3+ ion has 3 electrons fewer than its atom.","Z of the atom = electrons in the ion + 3."]},"q":{"options":[{"id":"a","feedback":"You removed the last electrons added, from 3d, but 4s is the outermost level in Ni."},{"id":"b","feedback":"Correct: both 4s electrons leave first, and 3d keeps its 8."},{"id":"c","feedback":"Taking one from each sublevel has no reason behind it: the outermost sublevel, 4s, empties first."},{"id":"d","feedback":"That is still the neutral atom, with 28 electrons. The 2+ ion has fewer."}],"explanation":"$\\ce{Ni^{2+}}$: $[\\text{Ar}]\\ 3d^8$. Check: 18 + 8 = 26 = 28 − 2."}},"s6":{"m":{"statement":"$\\ce{Cr^{2+}}$ is $[\\text{Ar}]\\ 4s^1\\ 3d^3$: the ion keeps the atom's $4s^1$.","correction":"The ion is built from the atom by emptying 4s first, so $\\ce{Cr^{2+}}$ is $[\\text{Ar}]\\ 3d^4$. Count: 18 + 4 = 22 = 24 − 2."}},"s8":{"q":{"options":[{"id":"a","feedback":"This keeps the atom's $4s^1$, but the ion empties 4s before it loses any 3d electron."},{"id":"b","feedback":"Correct: the single 4s electron leaves, then one 3d electron. 18 + 9 = 27 = 29 − 2."},{"id":"c","feedback":"Electrons do not move into 4s when an ion forms. They leave, starting from the outermost level."},{"id":"d","feedback":"18 + 10 = 28, so just one electron is gone, but a 2+ ion has lost two."}],"explanation":"Copper loses its single 4s electron first, then one 3d electron, so $\\ce{Cu^{2+}}$ is $[\\text{Ar}]\\ 3d^9$: 18 + 9 = 27 = 29 − 2."},"tf":{"explanation":"$\\ce{Ti^{2+}}$: $[\\text{Ar}]\\ 3d^2$. The book's table lists Ti as 2, 3, 4.","feedback_true":"Book point 3 makes one exception, scandium, and titanium is not that element.","feedback_false":"Right. Only Sc lacks +2; Ti loses its two 4s electrons to give $\\ce{Ti^{2+}}$."}},"s9":{"exam":{"body":"All elements of the first series have **oxidation state (+2)** after **losing the 4s electrons first** (except **scandium**). In higher states they **lose 3d electrons in sequence**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"أيوه. الـ 4s electrons موجودين في المستوى الخارجي، فهما اللي بيطلعوا الأول."},{"id":"b","feedback":"دي فكرة «آخر واحد دخل، أول واحد يطلع». الـ electrons مش بتطلع بعكس ترتيب الملء: بتطلع من الـ sublevel الأبعد عن الـ nucleus."},{"id":"c","feedback":"مفيش سبب ياخد واحد من كل sublevel: الـ electrons بتطلع من المستوى الخارجي الأول."}],"explanation":"الاتنين 4s electrons هما اللي بيطلعوا، عشان الـ 4s هو المستوى الخارجي. فالـ $\\ce{Fe^{2+}}$ بيبقى $[\\text{Ar}]\\ 3d^6$."}},"s2":{"m":{"statement":"الـ $\\ce{Fe^{2+}}$ يبقى $[\\text{Ar}]\\ 4s^2\\ 3d^4$: الـ electrons اللي دخلت آخر حاجة هي اللي بتطلع الأول.","correction":"صحيح الـ 4s بيتملى قبل الـ 3d، لكنه في المستوى الخارجي، فهو اللي بيفضى الأول. يعني الـ $\\ce{Fe^{2+}}$ هو $[\\text{Ar}]\\ 3d^6$."}},"s3":{"f":{"mistakes":[{"id":"m1","feedback":"إنت شلت 3d electrons، لكن الـ electrons بتطلع الأول من الـ sublevel اللي في المستوى الخارجي."},{"id":"m2","feedback":"كده الـ 4s لسه مليان، لكن الـ electrons اللي في المستوى الخارجي هي اللي بتطلع الأول."},{"id":"m3","feedback":"الـ 4s electrons مش بتتنقل للـ 3d: هي بتسيب الذرة."},{"id":"m4","feedback":"الـ ion فقد 2 electrons، والاتنين طالعين من الـ 4s."}],"explanation":"$\\ce{Co^{2+}}$: $[\\text{Ar}]\\ 4s^0\\ 3d^7$، وبنكتبها $[\\text{Ar}]\\ 3d^7$. اتأكد: 18 + 7 = 25 = 27 − 2."},"hl":{"hints":["الـ charge هي 2+، يعني 2 electrons هيطلعوا.","بيطلعوا من المستوى الخارجي الأول.","الـ 4s بيشيل 2 electrons؛ والـ 3d محدش بيلمسه."]}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"ده عدد الـ 3d لوحده، والـ ion فيه كمان electrons الـ [Ar]."},{"id":"m2","feedback":"إنت عدّيت الـ [Ar] لوحده، والـ ion فيه كمان الـ 3d electrons."},{"id":"m3","feedback":"الـ [Ar] لوحده مش هو الذرة: الذرة فيها كمان الـ 3d electrons والـ electrons اللي اتفقدت."},{"id":"m4","feedback":"الـ Z بتاع الذرة المتعادلة، والـ ion الـ 3+ عنده electrons أقل من الذرة بتاعته بـ 3."},{"id":"m5","feedback":"الـ ion الـ 3+ فقد 3 electrons، فالـ 3 دول بيترجعوا مرة واحدة على عدد الـ ion."}],"explanation":"18 + 3 = 21 electrons. الـ X فقد 3، يعني Z = 21 + 3 = 24: يبقى X هو الـ Cr، والـ ion هو $\\ce{Cr^{3+}}$."},"h":{"hints":["الـ [Ar] معناها 18 electrons.","الـ ion الـ 3+ عنده 3 electrons أقل من الذرة بتاعته.","Z بتاع الذرة = الـ electrons اللي في الـ ion + 3."]},"q":{"options":[{"id":"a","feedback":"إنت شلت آخر electrons دخلت، من الـ 3d، لكن الـ 4s هو المستوى الخارجي في الـ Ni وبيفضى الأول."},{"id":"b","feedback":"مظبوط: الاتنين 4s electrons بيطلعوا الأول، والـ 3d بيفضل محتفظ بالـ 8 بتوعه."},{"id":"c","feedback":"إنك تاخد واحد من كل sublevel ده مالوش أي سبب: الـ sublevel اللي في المستوى الخارجي هو اللي بيفضى الأول."},{"id":"d","feedback":"ده لسه الذرة المتعادلة نفسها، بـ 28 electrons. الـ ion الـ 2+ عنده أقل."}],"explanation":"$\\ce{Ni^{2+}}$: $[\\text{Ar}]\\ 3d^8$. اتأكد: 18 + 8 = 26 = 28 − 2."}},"s6":{"m":{"statement":"الـ $\\ce{Cr^{2+}}$ يبقى $[\\text{Ar}]\\ 4s^1\\ 3d^3$: الـ ion بيحتفظ بالـ $4s^1$ بتاع الذرة.","correction":"الـ ion بيتبني من الذرة بإن الـ 4s يفضى الأول، فالـ $\\ce{Cr^{2+}}$ بيبقى $[\\text{Ar}]\\ 3d^4$. عدّ: 18 + 4 = 22 = 24 − 2."}},"s8":{"q":{"options":[{"id":"a","feedback":"كده إنت سبت الـ $4s^1$ بتاع الذرة زي ما هو، لكن الـ ion بيفضّي الـ 4s الأول."},{"id":"b","feedback":"مظبوط: الـ 4s electron الوحيد بيطلع، وبعده 3d electron واحد. 18 + 9 = 27 = 29 − 2."},{"id":"c","feedback":"الـ electrons مش بتتنقل للـ 4s لما الـ ion بيتكوّن. هي بتطلع، والبداية من المستوى الخارجي."},{"id":"d","feedback":"18 + 10 = 28، يعني electron واحد تحديدًا اللي راح، والـ ion الـ 2+ فقد اتنين."}],"explanation":"الـ copper بيفقد الـ 4s electron الوحيد بتاعه الأول، وبعده 3d electron واحد، فالـ $\\ce{Cu^{2+}}$ يبقى $[\\text{Ar}]\\ 3d^9$: 18 + 9 = 27 = 29 − 2."},"tf":{"explanation":"$\\ce{Ti^{2+}}$: $[\\text{Ar}]\\ 3d^2$. جدول الكتاب بيدّي الـ Ti الحالات 2، 3، 4.","feedback_true":"النقطة 3 في الكتاب فيها استثناء واحد، وهو الـ scandium مش الـ titanium.","feedback_false":"صح. الـ Sc لوحده هو اللي مالوش +2؛ الـ Ti بيفقد الاتنين 4s electrons بتوعه ويدّي $\\ce{Ti^{2+}}$."}},"s9":{"exam":{"body":"كل عناصر السلسلة الأولى عندها **oxidation state (+2)** بعد ما **تفقد الـ 4s electrons الأول** (ما عدا الـ **scandium**). وفي الـ states الأعلى **بتفقد 3d electrons ورا بعض**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":3,"lesson_no":9,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-configuration","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Electronic configurations and oxidation states","duration_s":717.229,"start_s":180.7,"end_s":243.4,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.ion-configuration","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Ions: 4s electrons are lost first","duration_s":44.71,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.vanadium-ie","section_title":"Successive ionization energies of vanadium","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Successive ionization energies of vanadium"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-pt.oxidation-number","kind":"lesson","version":2,"catalog_version":3,"ord":178,"primary_concept_id":"pt.oxidation-number","concepts":[{"concept_id":"pt.oxidation-number","role":"primary"}],"title":"Oxidation state in compounds","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"+2","correct":true},{"id":"b","text":"−2","correct":false},{"id":"c","text":"+1","correct":false},{"id":"d","text":"0","correct":false}],"question":"Predict: in $\\ce{FeO}$, oxygen counts as −2. What does iron count as?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"$\\ce{Fe^{3+}}$ shows its charge. In $\\ce{Fe2O3}$ no charge is written, yet the book calls it iron (III) oxide."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"No charge written"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Simple ions are easy: read the charge. In a compound, you calculate it."},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Oxidation state","definition":"The charge an atom has, or seems to have, in a compound or ion. It is written with a sign, like +2 or −1."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["An element on its own (Fe, $\\ce{H2}$)","0"],["A simple ion ($\\ce{Fe^{3+}}$, $\\ce{Cl-}$)","its charge (+3, −1)"]],"caption":"The two easy cases","headers":["Particle","Oxidation state"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["kt","tb","t"]}}},"title":"Oxidation state"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"r1":{"type":"Reveal","props":{"label":"Step 1: Call iron x"},"children":["r1t"]},"r2":{"type":"Reveal","props":{"label":"Step 2: Make the sum zero"},"children":["r2f"]},"r3":{"type":"Reveal","props":{"label":"Step 3: Name it"},"children":["r3t"]},"tb":{"type":"DataTable","props":{"rows":[["O","usually −2"],["Na, K","+1"],["Cl in chlorides","−1"],["$\\ce{SO4}$ group (as a whole)","−2"],["Sum of all oxidation states","0"]],"caption":"Rules you need in Chapter 1","headers":["In a compound","Value"]},"children":[]},"r1t":{"type":"Text","props":{"content":"Two Fe atoms give 2x. Three O atoms give 3 × (−2)."},"children":[]},"r2f":{"type":"Formula","props":{"latex":"2x + 3(-2) = 0 \\;\\Rightarrow\\; 2x = +6 \\;\\Rightarrow\\; x = +3"},"children":[]},"r3t":{"type":"Text","props":{"content":"Iron is +3, so $\\ce{Fe2O3}$ is iron (III) oxide. The Roman numeral is the metal's oxidation state."},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["tb","r1","r2","r3"]}}},"title":"Worked: iron in Fe₂O₃"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"x":0},"elements":{"t":{"type":"Text","props":{"content":"Cl in a chloride counts as −1. Move the slider until the sum for $\\ce{CrCl3}$ is zero."},"children":[]},"ok":{"type":"Callout","props":{"variant":"tip"},"visible":{"eq":3,"$state":"/x"},"children":[]},"s1":{"type":"Stat","props":{"tone":"info","label":"3 Cl atoms","value":-3},"children":[]},"s2":{"type":"Stat","props":{"tone":"warning","label":"sum: x + 3(−1)","value":{"args":{"x":{"$state":"/x"},"expr":"x - 3","digits":0},"$computed":"calc"}},"children":[]},"sl":{"type":"Slider","props":{"max":7,"min":-3,"step":1,"label":"oxidation state of Cr","value":{"$bindState":"/x"}},"children":[]},"st":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["s1","s2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","st","ok"]}}},"title":"Balance chromium in CrCl₃"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"In $\\ce{KMnO4}$, the oxidation state of Mn is ___.","answers":[["+7","7","+ 7"]],"mistakes":[{"id":"m1","blank":0,"answer":"+8"},{"id":"m2","blank":0,"answer":"8"},{"id":"m3","blank":0,"answer":"-7"},{"id":"m4","blank":0,"answer":"−7"},{"id":"m5","blank":0,"answer":"+2"},{"id":"m6","blank":0,"answer":"+1"}]},"children":[]},"h":{"type":"HintLadder","props":{},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"iron (III) sulphate","correct":true},{"id":"b","text":"iron (II) sulphate","correct":false},{"id":"c","text":"iron (VI) sulphate","correct":false}],"question":"What is the name of $\\ce{Fe2(SO4)3}$?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","h","q"]}}},"title":"Your turn"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Element alone = 0; simple ion = its charge.","In a compound the oxidation states add up to 0: O = −2, Na and K = +1, Cl in chlorides = −1, $\\ce{SO4}$ = −2.","The Roman numeral in a name is the metal's oxidation state: iron (II) = +2, iron (III) = +3."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["anst"]},"anst":{"type":"Text","props":{"content":"Cl in chlorides counts as −1. In $\\ce{FeCl3}$ three Cl give −3, so iron is +3; in $\\ce{FeCl2}$ two Cl give −2, so iron is +2. The sum is 0 each time."},"children":[]},"next":{"type":"Text","props":{"muted":true,"content":"Next in Chapter 1: the book's table lists each metal's oxidation states with its compounds."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","next","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why iron is +3 in $\\ce{FeCl3}$ but +2 in $\\ce{FeCl2}$?"},"children":[]}}},"title":"Summary"}],"title":"Oxidation state in compounds","minutes":5,"book_ref":"Background for Ch.1 The Electronic Configurations and Oxidation states, pp.8-10 (table of oxidation states and compounds)","subtitle":"Finding the metal's oxidation state from a formula","objectives":["Find the oxidation state of an element in a compound (sum = 0) or in an atomic group (sum = its charge).","Use O = −2, Na and K = +1, Cl in chlorides = −1 and the $\\ce{SO4}$ group = −2.","Name a compound with a Roman numeral, e.g. iron (II), iron (III)."],"concept_ids":["pt.oxidation-number"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Yes: +2 and −2 add up to zero, like any neutral compound."},{"id":"b","feedback":"Then the total would be −4, but a neutral compound carries no total charge."},{"id":"c","feedback":"+1 and −2 add up to −1, not zero."},{"id":"d","feedback":"Zero is for an element on its own. Here iron is combined with oxygen."}],"explanation":"A neutral compound has a total charge of zero. With oxygen at −2, iron in $\\ce{FeO}$ counts as +2, because +2 + (−2) = 0."}},"s4":{"ok":{"body":"The sum is zero. Cr is +3, so $\\ce{CrCl3}$ is chromium (III) chloride.","title":"Balanced"}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"You left out potassium, which counts as +1 in the sum."},{"id":"m2","feedback":"You left out potassium, which counts as +1 in the sum."},{"id":"m3","feedback":"The sign is wrong: the four O atoms give a negative total, so Mn must be positive to cancel it."},{"id":"m4","feedback":"The sign is wrong: the four O atoms give a negative total, so Mn must be positive to cancel it."},{"id":"m5","feedback":"That uses too few O atoms: $\\ce{KMnO4}$ has four O atoms, each −2."},{"id":"m6","feedback":"That uses too few O atoms: $\\ce{KMnO4}$ has four O atoms, each −2."}],"explanation":"+1 + x + 4(−2) = 0, so x = +7."},"h":{"hints":["K counts +1 and each O counts −2.","Four O atoms give −8.","+1 + x − 8 must equal 0."]},"q":{"options":[{"id":"a","feedback":"Right: 2x + 3(−2) = 0, so x = +3."},{"id":"b","feedback":"Three $\\ce{SO4}$ groups give −6, and two Fe atoms at +2 give only +4, which does not cancel it."},{"id":"c","feedback":"You gave the whole positive total to one Fe, but that total is shared between the two Fe atoms."}],"explanation":"Three $\\ce{SO4}$ groups give −6; two Fe atoms share +6, so each is +3."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"أيوه: +2 و −2 مجموعهم صفر، زي أي compound متعادل."},{"id":"b","feedback":"كده المجموع هيبقى −4، والـ compound المتعادل مجموعه صفر."},{"id":"c","feedback":"+1 و −2 مجموعهم −1، مش صفر، فالقيمة دي مش بتوازن الـ −2."},{"id":"d","feedback":"الصفر ده للعنصر لوحده. هنا الـ iron متحد مع الـ oxygen."}],"explanation":"الـ compound المتعادل مجموع الـ charges فيه صفر. ولما الـ oxygen يبقى −2، الـ iron في الـ $\\ce{FeO}$ يتحسب +2، عشان +2 + (−2) = 0."}},"s4":{"ok":{"body":"المجموع بقى صفر. الـ Cr بـ +3، عشان كده الـ $\\ce{CrCl3}$ اسمه chromium (III) chloride.","title":"اتوازنت"}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"نسيت الـ potassium: الـ K بيتحسب +1، ولازم يدخل في المجموع."},{"id":"m2","feedback":"نسيت الـ potassium: الـ K بيتحسب +1، ولازم يدخل في المجموع."},{"id":"m3","feedback":"الإشارة غلط: الـ 4 O atoms بيدّوا مجموع سالب، فالـ Mn لازم إشارته تبقى موجبة عشان يلغيه."},{"id":"m4","feedback":"الإشارة غلط: الـ 4 O atoms بيدّوا مجموع سالب، فالـ Mn لازم إشارته تبقى موجبة عشان يلغيه."},{"id":"m5","feedback":"في $\\ce{KMnO4}$ فيه 4 O atoms، وكلها لازم تدخل في المجموع."},{"id":"m6","feedback":"في $\\ce{KMnO4}$ فيه 4 O atoms، وكلها لازم تدخل في المجموع."}],"explanation":"+1 + x + 4(−2) = 0، يبقى x = +7."},"h":{"hints":["الـ K بيتحسب +1، والـ O الواحدة بتتحسب −2.","الـ 4 O atoms بيدّوا −8.","+1 + x − 8 لازم يساوي 0."]},"q":{"options":[{"id":"a","feedback":"صح: 2x + 3(−2) = 0، يبقى x = +3."},{"id":"b","feedback":"فيه تلات $\\ce{SO4}$ groups، والواحدة بـ −2، يعني −6، والـ iron بـ +2 مع 2 Fe atoms مش هيلغي الـ −6."},{"id":"c","feedback":"إنت إديت المجموع الموجب كله لـ Fe واحدة، والمجموع ده متقسم على الـ 2 Fe atoms."}],"explanation":"تلات $\\ce{SO4}$ groups بيدّوا −6، والـ 2 Fe atoms بيتقسموا الـ +6، فالواحدة منهم +3."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":3,"is_basics":true,"lesson_no":3,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":204.2,"end_s":235.4,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-pt.oxidation-number","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Oxidation state in compounds","duration_s":46.37,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-redox.electronic","kind":"lesson","version":3,"catalog_version":3,"ord":180,"primary_concept_id":"redox.electronic","concepts":[{"concept_id":"redox.electronic","role":"primary"}],"title":"Oxidation and reduction by electrons","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It lost one electron","correct":true},{"id":"b","text":"It gained one electron","correct":false},{"id":"c","text":"Nothing: without oxygen it cannot be oxidation","correct":false}],"question":"Predict: what happened to the iron ion?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"In Chapter 1, $\\ce{Fe^{2+}}$ changes to $\\ce{Fe^{3+}}$. No oxygen is gained, yet the book calls it oxidation."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Oxidation without oxygen?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{Fe^{2+} -> Fe^{3+} + e-}","caption":"Loses one electron: +2 → +3"},"children":[]},"r":{"type":"Text","props":{"muted":true,"content":"Remember: you met oxidation as gain of oxygen. Here is a wider meaning."},"children":[]},"t":{"type":"Text","props":{"content":"Gaining oxygen is one case of this. In MgO, Mg has lost two electrons to oxygen: 0 → +2."},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Oxidation","definition":"A process in which an atom or ion loses electrons, so its oxidation state increases."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["r","kt","f","t"]}}},"title":"Oxidation: loss of electrons"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{Cu^{2+} + 2e- -> Cu}","caption":"Gains two electrons: +2 → 0"},"children":[]},"t":{"type":"Text","props":{"content":"The two happen together. Electrons lost by one substance are gained by another."},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Reduction","definition":"A process in which an atom or ion gains electrons, so its oxidation state decreases."},"children":[]},"tip":{"type":"Callout","props":{"variant":"tip"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["kt","f","t","tip"]}}},"title":"Reduction: gain of electrons"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Zn + CuSO4 ->}\\\\ \\ce{ZnSO4 + Cu}\\end{gathered}"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"r1":{"type":"Reveal","props":{"label":"Step 1: Oxidation states"},"children":["r1t"]},"r2":{"type":"Reveal","props":{"label":"Step 2: Who lost, who gained?"},"children":["r2t"]},"r3":{"type":"Reveal","props":{"label":"Step 3: The agents"},"children":["r3t"]},"r1t":{"type":"Text","props":{"content":"Zn: 0 → +2. Cu: +2 → 0. The $\\ce{SO4}$ group stays −2."},"children":[]},"r2t":{"type":"Text","props":{"content":"Zn lost 2 electrons: it is oxidized. $\\ce{Cu^{2+}}$ gained 2 electrons: it is reduced."},"children":[]},"r3t":{"type":"Text","props":{"content":"Zn is the reducing agent: it is itself oxidized. $\\ce{CuSO4}$ is the oxidizing agent: it is itself reduced."},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["f","r1","r2","r3","m"]}}},"title":"Worked: zinc in copper sulphate"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"na","text":"$\\ce{Na -> Na+ + e-}$"},{"id":"cl","text":"$\\ce{Cl2 + 2e- -> 2Cl-}$"},{"id":"sn","text":"$\\ce{Sn^{2+} -> Sn^{4+} + 2e-}$"},{"id":"fe","text":"$\\ce{Fe^{3+} + e- -> Fe^{2+}}$"}],"answer":{"ox":["na","sn"],"red":["cl","fe"]},"prompt":"Sort each change.","categories":[{"id":"ox","label":"Oxidation"},{"id":"red","label":"Reduction"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{Cl2}$","correct":true},{"id":"b","text":"Na","correct":false},{"id":"c","text":"None: no oxygen is involved","correct":false},{"id":"d","text":"NaCl","correct":false}],"question":"In $\\ce{2Na + Cl2 -> 2NaCl}$, which is the oxidizing agent?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Your turn"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Oxidation: loss of electrons; the oxidation state increases.","Reduction: gain of electrons; the oxidation state decreases.","The oxidizing agent gains electrons (it is reduced). The reducing agent loses electrons (it is oxidized)."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["anst"]},"anst":{"type":"Text","props":{"content":"In $\\ce{2Na + Cl2 -> 2NaCl}$, chlorine gains electrons (0 → −1), so it is reduced. The substance that gains electrons is the oxidizing agent, with or without oxygen."},"children":[]},"back":{"type":"Text","props":{"content":"Back to the hook: $\\ce{Fe^{2+} -> Fe^{3+} + e-}$ is oxidation. Next lesson: why it happens so easily."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","back","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why $\\ce{Cl2}$ is an oxidizing agent, though no oxygen is involved?"},"children":[]}}},"title":"Summary"}],"title":"Oxidation and reduction by electrons","minutes":5,"book_ref":"Background for Ch.1 worked exercise, p.9 (iron (II) is oxidized to iron (III))","subtitle":"Oxidation without oxygen","objectives":["Define oxidation as loss of electrons (oxidation state increases) and reduction as gain of electrons (oxidation state decreases).","Identify what is oxidized and reduced in a reaction with no oxygen.","Identify the oxidizing agent (it is reduced) and the reducing agent (it is oxidized)."],"concept_ids":["redox.electronic"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Yes: going from 2+ to 3+ means one more electron is gone."},{"id":"b","feedback":"An electron is negative, so gaining one would lower the charge, but the charge rose."},{"id":"c","feedback":"That is the oxygen-only idea; oxidation has a wider meaning, not tied to oxygen."}],"explanation":"Going from $\\ce{Fe^{2+}}$ to $\\ce{Fe^{3+}}$, the ion loses one electron. Oxidation is loss of electrons, so this is oxidation even without oxygen."}},"s3":{"tip":{"body":"OIL RIG: Oxidation Is Loss, Reduction Is Gain (of electrons).","title":"Memory aid"}},"s4":{"m":{"statement":"Oxidation always needs oxygen.","correction":"Zinc gains no oxygen here, yet it loses electrons, so it is oxidized. Gaining oxygen is just one case of oxidation."}},"s5":{"c":{"items":[{"id":"na","feedback":"The electron is on the right side: it is given out."},{"id":"cl","feedback":"The electrons are on the left side, so they are taken in, and chlorine goes from 0 to −1."},{"id":"sn","feedback":"The charge goes from +2 to +4, a rise, with electrons given out."},{"id":"fe","feedback":"The charge goes from +3 to +2: the ion gained an electron."}],"explanation":"Electrons given out (on the right) = oxidation; electrons taken in (on the left) = reduction."},"q":{"options":[{"id":"a","feedback":"Right: chlorine gains electrons (0 → −1), so it is reduced. That makes it the oxidizing agent."},{"id":"b","feedback":"Na loses electrons, so it is oxidized; the oxidizing agent is the one that is itself reduced."},{"id":"c","feedback":"That is the oxygen-only idea again: the oxidizing agent is the substance that gains electrons, with or without oxygen."},{"id":"d","feedback":"NaCl is the product, and agents are reactants."}],"explanation":"Na: 0 → +1 (oxidized, reducing agent). Cl: 0 → −1 (reduced, oxidizing agent)."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"أيوه: لما يروح من 2+ لـ 3+ يبقى فيه electron كمان راح منه."},{"id":"b","feedback":"الـ electron شايل negative charge، فلو كسب واحد الـ charge كانت هتقل، لكنها زادت."},{"id":"c","feedback":"دي فكرة «مفيش oxidation من غير oxygen»، والـ oxidation معناه أوسع من كده."}],"explanation":"لما الـ $\\ce{Fe^{2+}}$ يتحوّل لـ $\\ce{Fe^{3+}}$ بيفقد electron واحد. والـ oxidation هو فقد electrons، فده oxidation حتى من غير oxygen."}},"s3":{"tip":{"body":"افتكر OIL RIG: Oxidation Is Loss، Reduction Is Gain، والكلام هنا عن الـ electrons.","title":"طريقة تفتكرها"}},"s4":{"m":{"statement":"الـ oxidation لازم يكون فيه oxygen.","correction":"بص على الـ zinc هنا: مكسبش أي oxygen، ومع ذلك خسر electrons، يبقى هو oxidized. كسب الـ oxygen ده مجرد حالة واحدة من الـ oxidation."}},"s5":{"c":{"items":[{"id":"na","feedback":"الـ electron هنا طالع على اليمين، مش داخل على الشمال."},{"id":"cl","feedback":"الـ electrons اللي على الشمال دي داخلة، فالـ oxidation state بينزل."},{"id":"sn","feedback":"الـ charge بتروح من +2 لـ +4، يعني طلوع."},{"id":"fe","feedback":"الـ charge بتروح من +3 لـ +2، يعني الـ ion كسب electron."}],"explanation":"الـ electrons اللي طالعة (على يمين المعادلة) = oxidation؛ والـ electrons اللي داخلة (على شمال المعادلة) = reduction."},"q":{"options":[{"id":"a","feedback":"صح: الـ chlorine بيكسب electrons (0 → −1)، يبقى هو reduced. وده اللي بيخليه الـ oxidizing agent."},{"id":"b","feedback":"الـ Na بيخسر electrons، يبقى هو oxidized، والـ oxidizing agent هو اللي نفسه بيبقى reduced."},{"id":"c","feedback":"دي تاني فكرة «مفيش oxidation من غير oxygen»: الـ oxidation والـ reduction هنا بيحصلوا بنقل electrons من غير أي oxygen."},{"id":"d","feedback":"الـ NaCl ده product، والـ agents بيبقوا reactants."}],"explanation":"الـ Na: من 0 → +1 (oxidized، يعني هو الـ reducing agent). الـ Cl: من 0 → −1 (reduced، يعني هو الـ oxidizing agent)."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":4,"is_basics":true,"lesson_no":4,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":373.8,"end_s":435.2,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-redox.electronic","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Oxidation and reduction by electrons","duration_s":50.39,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":83,"page_to":84,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"exercise":"Exercise","relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.fe2-fe3-mn2-stability","kind":"lesson","version":2,"catalog_version":3,"ord":182,"primary_concept_id":"te.fe2-fe3-mn2-stability","concepts":[{"concept_id":"te.fe2-fe3-mn2-stability","role":"primary"}],"title":"Iron(II) is easily oxidized while manganese(II) is not","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{Fe^{2+}}$","correct":true},{"id":"b","text":"$\\ce{Mn^{2+}}$","correct":false},{"id":"c","text":"Both equally: they have the same charge","correct":false}],"question":"Predict: which one is easily oxidized to the 3+ ion?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"$\\ce{Fe^{2+}}$ and $\\ce{Mn^{2+}}$ can each lose one more electron. One does it easily; the other does not."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Who gives up one more electron?"},{"id":"s2","kind":"interact","spec":{"root":"root","state":{"k":0},"elements":{"t":{"type":"Text","props":{"content":"Remove electrons from Fe and Mn. Remember: the 4s electrons leave first."},"children":[]},"cf":{"type":"Card","props":{"title":"Iron (Z = 26)"},"children":["f0","f1","f2"]},"cm":{"type":"Card","props":{"title":"Manganese (Z = 25)"},"children":["m0","m1","m2"]},"f0":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":6}],"caption":"Fe: $[\\text{Ar}]\\ 4s^2\\ 3d^6$","show_unpaired":true},"visible":{"eq":0,"$state":"/k"},"children":[]},"f1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":6}],"caption":"one 4s electron gone","show_unpaired":true},"visible":{"eq":1,"$state":"/k"},"children":[]},"f2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":6}],"caption":"$\\ce{Fe^{2+}}$: $[\\text{Ar}]\\ 3d^6$","show_unpaired":true},"visible":{"eq":2,"$state":"/k"},"children":[]},"m0":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":5}],"caption":"Mn: $[\\text{Ar}]\\ 4s^2\\ 3d^5$","show_unpaired":true},"visible":{"eq":0,"$state":"/k"},"children":[]},"m1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":5}],"caption":"one 4s electron gone","show_unpaired":true},"visible":{"eq":1,"$state":"/k"},"children":[]},"m2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":5}],"caption":"$\\ce{Mn^{2+}}$: $[\\text{Ar}]\\ 3d^5$","show_unpaired":true},"visible":{"eq":2,"$state":"/k"},"children":[]},"sl":{"type":"Slider","props":{"max":2,"min":0,"step":1,"label":"electrons lost","value":{"$bindState":"/k"}},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["cf","cm"]},"look":{"type":"Callout","props":{"variant":"tip"},"visible":{"eq":2,"$state":"/k"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","cols","look"]}}},"title":"Make the 2+ ions"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{Fe^{2+} ->[\\text{oxidation}] Fe^{3+} + e-}"},"children":[]},"n":{"type":"Text","props":{"muted":true,"content":"The electron that leaves is the paired one. Now every 3d orbital holds one electron."},"children":[]},"t":{"type":"Text","props":{"content":"Iron (III) ion is more stable, as its 3d sublevel is half filled ($3d^5$). So the reaction goes toward the more stable ion."},"children":[]},"b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":6}],"caption":"$[\\text{Ar}]\\ 3d^6$","show_unpaired":true},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":5}],"caption":"$[\\text{Ar}]\\ 3d^5$: half filled, more stable","show_unpaired":true},"children":[]},"c1":{"type":"Card","props":{"tone":"warning","title":"$\\ce{Fe^{2+}}$"},"children":["b1"]},"c2":{"type":"Card","props":{"tone":"success","title":"$\\ce{Fe^{3+}}$"},"children":["b2"]},"cols":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","cols","t","n"]}}},"title":"Iron (II) → iron (III)"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"$\\ce{Mn^{3+}}$ = [Ar] 3d___ . After oxidation, the 3d sublevel is ___ half filled (type: still / no longer).","answers":[["4","four"],["no longer","not"]],"mistakes":[{"id":"m1","blank":0,"answer":"5"},{"id":"m2","blank":0,"answer":"6"},{"id":"m3","blank":0,"answer":"3"},{"id":"m4","blank":1,"answer":"still"}]},"children":[]},"t":{"type":"Text","props":{"content":"Same steps for Mn. $\\ce{Mn^{2+}}$ is $[\\text{Ar}]\\ 3d^5$. Oxidation removes one more electron."},"children":[]},"b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":5}],"caption":"$[\\text{Ar}]\\ 3d^5$: half filled, more stable","show_unpaired":true},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":4}],"caption":"$[\\text{Ar}]\\ 3d^4$","show_unpaired":true},"children":[]},"bk":{"type":"Text","props":{"content":"The 3d sublevel is half filled ($3d^5$) in $\\ce{Mn^{2+}}$, so it is more stable than $\\ce{Mn^{3+}}$. So $\\ce{Mn^{2+}}$ is not readily oxidized to $\\ce{Mn^{3+}}$."},"children":[]},"c1":{"type":"Card","props":{"tone":"success","title":"$\\ce{Mn^{2+}}$"},"children":["b1"]},"c2":{"type":"Card","props":{"tone":"warning","title":"$\\ce{Mn^{3+}}$"},"children":["b2"]},"rv":{"type":"Reveal","props":{"label":"Show the boxes and the book's answer"},"children":["cols","bk"]},"cols":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"root":{"type":"Stack","props":{"gap":"md"},"children":["t","f","rv"]}}},"title":"Your turn: manganese (II) → manganese (III)"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Iron has 8 electrons in 4s and 3d, but it does not reach +8. The book says all its states above +3 are not important."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a","label":"lose 4s²"},{"to":"c","from":"b","label":"lose one 3d electron"}],"nodes":[{"id":"a","label":"Fe: [Ar] 4s² 3d⁶"},{"id":"b","label":"Fe²⁺ (+2): the two 4s electrons lost"},{"id":"c","label":"Fe³⁺ (+3): half-filled 3d⁵, stable"}],"layout":"vertical","caption":"Book pp.20-21: iron's two important oxidation states"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fd","t","m"]}}},"title":"Iron's important oxidation states"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{Fe^{3+}}$ and $\\ce{Mn^{2+}}$","correct":true},{"id":"b","text":"$\\ce{Fe^{2+}}$ and $\\ce{Mn^{3+}}$","correct":false},{"id":"c","text":"$\\ce{Fe^{3+}}$ and $\\ce{Mn^{3+}}$","correct":false},{"id":"d","text":"$\\ce{Fe^{2+}}$ and $\\ce{Mn^{2+}}$","correct":false}],"question":"Which two ions both have the stable half-filled $3d^5$ sublevel?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"$\\ce{Fe^{3+}}$ is more stable than $\\ce{Fe^{2+}}$ because its charge is bigger."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Same 3d, different ions"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"o":{"type":"Ordering","props":{"items":[{"id":"a","text":"$\\ce{_{26}Fe}$: $[\\text{Ar}]\\ 4s^2\\ 3d^6$"},{"id":"b","text":"$\\ce{Fe^{2+}}$: $[\\text{Ar}]\\ 3d^6$ (the two 4s electrons are lost first)"},{"id":"c","text":"$\\ce{Fe^{3+}}$: $[\\text{Ar}]\\ 3d^5$"},{"id":"d","text":"The 3d sublevel of $\\ce{Fe^{3+}}$ is half filled, so it is more stable"},{"id":"e","text":"So the reaction goes toward forming $\\ce{Fe^{3+}}$"}],"prompt":"Put the answer to 'Iron (II) is easily oxidized to iron (III)' in order."},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"+2 and +3","correct":true},{"id":"b","text":"+2, +3 and +8","correct":false},{"id":"c","text":"+3 only","correct":false},{"id":"d","text":"+2, +3 and +6","correct":false}],"question":"Which oxidation states of iron does the book call important?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o","q"]}}},"title":"Build the exam answer"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["$\\ce{Fe^{2+}}$ $3d^6$ → $\\ce{Fe^{3+}}$ $3d^5$: oxidation gives a half-filled 3d, so it is easy.","$\\ce{Mn^{2+}}$ is already $3d^5$. Losing one more electron would break it.","Iron's important states: +2 and +3. States above +3 are not important."]},"children":[]},"ans":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"The two ions in 3d boxes"}},"children":["ans_t","ans_c"]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Give reasons"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","ans"]},"self":{"type":"Text","props":{"content":"Back to the hook: the same $3d^5$ makes one ion change easily and the other not. Can you explain why, with 3d boxes?"},"children":[]},"ans_c":{"type":"Columns","props":{"columns":2},"children":["ans_fe","ans_mn"]},"ans_t":{"type":"Text","props":{"content":"$\\ce{Fe^{2+}}$ ($3d^6$) loses one 3d electron and becomes $\\ce{Fe^{3+}}$ ($3d^5$): half filled, so the oxidation is easy. $\\ce{Mn^{2+}}$ is already $3d^5$: losing one more electron would break the half-filled 3d and give $\\ce{Mn^{3+}}$ ($3d^4$)."},"children":[]},"ans_fe":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"3d","electrons":5}],"caption":"$\\ce{Fe^{3+}}$: $[\\text{Ar}]\\ 3d^5$","show_unpaired":true},"children":[]},"ans_mn":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"3d","electrons":4}],"caption":"$\\ce{Mn^{3+}}$: $[\\text{Ar}]\\ 3d^4$","show_unpaired":true},"children":[]}}},"title":"Summary"}],"title":"Iron(II) is easily oxidized while manganese(II) is not","minutes":9,"book_ref":"Ch.1 worked exercise, p.9; Iron: chemical properties (oxidation states), pp.20-21","subtitle":"The half-filled 3d⁵ decides","objectives":["Write and draw $\\ce{Fe^{2+}}$, $\\ce{Fe^{3+}}$, $\\ce{Mn^{2+}}$ and $\\ce{Mn^{3+}}$ in 3d boxes.","Explain why iron (II) is easily oxidized to iron (III), while Mn (II) is not readily oxidized to Mn (III).","State iron's important oxidation states: +2 and +3 (states above +3 are not important)."],"concept_ids":["te.fe2-fe3-mn2-stability"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good prediction. The 3d boxes will show why."},{"id":"b","feedback":"Mn has fewer electrons, so it may look easier. But $\\ce{Mn^{2+}}$ is already $3d^5$, a stable half-filled sublevel."},{"id":"c","feedback":"Same charge, but different 3d sublevels. The charge alone does not decide."}],"explanation":"$\\ce{Fe^{2+}}$ is easily oxidized to $\\ce{Fe^{3+}}$: losing one 3d electron turns its $3d^6$ into the stable half-filled $3d^5$. $\\ce{Mn^{2+}}$ is already $3d^5$, so it is hard to oxidize to $\\ce{Mn^{3+}}$."}},"s2":{"look":{"body":"$\\ce{Mn^{2+}}$ is already $3d^5$: half filled. $\\ce{Fe^{2+}}$ is $3d^6$: one orbital holds a pair.","title":"Look at the 3d boxes"}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"That is still $\\ce{Mn^{2+}}$; oxidation takes one more electron away."},{"id":"m2","feedback":"Oxidation is a loss of electrons, not a gain, so the 3d count goes down."},{"id":"m3","feedback":"Going from 2+ to 3+ removes just one electron from $\\ce{Mn^{2+}}$ ($3d^5$)."},{"id":"m4","feedback":"After oxidation one of the five 3d orbitals is empty, and a half-filled 3d needs one electron in each orbital."}],"explanation":"$\\ce{Mn^{3+}}$: $[\\text{Ar}]\\ 3d^4$: one 3d orbital is now empty."}},"s5":{"m":{"statement":"Iron can reach +8 by losing all its 4s and 3d electrons.","correction":"Iron does not reach +8. Its +6 state in $\\ce{Na2FeO4}$ exists, but it is not important: iron's important states are +2 and +3."}},"s6":{"q":{"options":[{"id":"a","feedback":"Right: each has 23 electrons, 18 + 5, so both are $[\\text{Ar}]\\ 3d^5$."},{"id":"b","feedback":"These two are reversed: $\\ce{Fe^{2+}}$ is $3d^6$ and $\\ce{Mn^{3+}}$ is $3d^4$, so neither is $3d^5$."},{"id":"c","feedback":"That picks the bigger charge, but stability here comes from the 3d count, and $\\ce{Mn^{3+}}$ is $3d^4$, not $3d^5$."},{"id":"d","feedback":"Same charge does not mean same 3d: $\\ce{Fe^{2+}}$ is $3d^6$, not $3d^5$."}],"explanation":"Electrons: $\\ce{Fe^{3+}}$ 26 − 3 = 23, $\\ce{Mn^{2+}}$ 25 − 2 = 23. Both are $[\\text{Ar}]\\ 3d^5$."},"tf":{"explanation":"The book's reason is the half-filled 3d sublevel ($3d^5$), not the size of the charge.","feedback_true":"If a bigger charge meant more stable, $\\ce{Mn^{3+}}$ would beat $\\ce{Mn^{2+}}$, yet $\\ce{Mn^{2+}}$ is the stable one: the 3d count decides, not the charge.","feedback_false":"Right to reject it. The reason is the half-filled $3d^5$ of $\\ce{Fe^{3+}}$, not its charge."}},"s7":{"o":{"items":[{"id":"a","feedback":"The ions' configurations are built from the atom's configuration, $[\\text{Ar}]\\ 4s^2\\ 3d^6$."},{"id":"b","feedback":"$\\ce{Fe^{2+}}$ forms when iron loses its two 4s electrons, before any 3d electron is lost."},{"id":"c","feedback":"$\\ce{Fe^{3+}}$ needs one more electron lost, from $\\ce{Fe^{2+}}$."},{"id":"d","feedback":"Stability is judged from the configuration, so it needs the $3d^5$ of $\\ce{Fe^{3+}}$ already given."},{"id":"e","feedback":"This line is the conclusion, drawn from the stability reason."}],"explanation":"Atom → $\\ce{Fe^{2+}}$ → $\\ce{Fe^{3+}}$ → half-filled $3d^5$ is more stable → the reaction goes toward $\\ce{Fe^{3+}}$."},"q":{"options":[{"id":"a","feedback":"Right: +2 from losing 4s², and +3 with the stable half-filled 3d⁵."},{"id":"b","feedback":"Iron has 8 electrons in 4s and 3d, but it does not actually reach +8."},{"id":"c","feedback":"+3 is not the only important state: iron also forms a state by losing just its two 4s electrons."},{"id":"d","feedback":"+6 exists, in $\\ce{Na2FeO4}$, but the book says the states above +3 are not important."}],"explanation":"The book calls +2 and +3 the important oxidation states of iron: +2 from losing the two 4s electrons, and +3 with the stable half-filled $3d^5$. The states above +3 are not important."}},"s8":{"exam":{"body":"**Fe³⁺** ([Ar] 3d⁵) is more stable than **Fe²⁺** ([Ar] 3d⁶) because its **3d sublevel is half filled**. **Mn²⁺** is **already half filled (3d⁵)**, so it is **more stable than Mn³⁺**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"توقّع حلو. مربعات الـ 3d هتوريك السبب."},{"id":"b","feedback":"الـ Mn عنده electrons أقل، فممكن يبان إنه أسهل. لكن الـ $\\ce{Mn^{2+}}$ عنده $3d^5$ نصه مليان ومستقر، فصعب يخسر منه electron."},{"id":"c","feedback":"نفس الـ charge أيوه، لكن الـ 3d sublevels مختلفة. الـ charge لوحده مش هو اللي بيحدد."}],"explanation":"الـ $\\ce{Fe^{2+}}$ هو اللي بيتأكسد بسهولة لـ $\\ce{Fe^{3+}}$: لما يخسر 3d electron واحد، الـ $3d^6$ بتاعه بيبقى $3d^5$ نصه مليان ومستقر. إنما الـ $\\ce{Mn^{2+}}$ أصلًا $3d^5$، فصعب يتأكسد لـ $\\ce{Mn^{3+}}$."}},"s2":{"look":{"body":"الـ $\\ce{Mn^{2+}}$ أصلًا $3d^5$: نصه مليان. أما الـ $\\ce{Fe^{2+}}$ فهو $3d^6$: فيه orbital شايل زوج.","title":"بص على مربعات الـ 3d"}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"ده لسه $\\ce{Mn^{2+}}$، والـ oxidation بتشيل electron كمان من الـ 3d."},{"id":"m2","feedback":"الـ oxidation خسارة electrons، مش اكتساب، فعدد الـ 3d مش ممكن يزيد."},{"id":"m3","feedback":"من 2+ لـ 3+ بيتشال electron واحد لا أكتر من الـ $\\ce{Mn^{2+}}$ ($3d^5$)."},{"id":"m4","feedback":"بعد الـ oxidation فيه electron اتشال من المربعات الخمسة، فواحد منهم بقى فاضي."}],"explanation":"$\\ce{Mn^{3+}}$: $[\\text{Ar}]\\ 3d^4$: يعني فيه 3d orbital بقى فاضي."}},"s5":{"m":{"statement":"الـ Fe ممكن يوصل لـ +8 لو خسر كل الـ electrons اللي في الـ 4s والـ 3d.","correction":"الـ Fe مابيوصلش لـ +8. الـ oxidation state +6 بتاعته في الـ $\\ce{Na2FeO4}$ موجودة، لكنها مش مهمة: الحالات المهمة للـ Fe هي +2 و+3."}},"s6":{"q":{"options":[{"id":"a","feedback":"صح: كل واحد فيهم عنده 23 electrons، يعني 18 + 5، فالاتنين $[\\text{Ar}]\\ 3d^5$."},{"id":"b","feedback":"الاتنين دول معكوسين: الـ $\\ce{Fe^{2+}}$ هو $3d^6$ والـ $\\ce{Mn^{3+}}$ هو $3d^4$، يعني مفيش فيهم $3d^5$."},{"id":"c","feedback":"كده إنت اخترت على أساس الـ charge الأكبر. الاستقرار هنا جاي من عدد الـ 3d، والـ $\\ce{Mn^{3+}}$ هو $3d^4$ مش $3d^5$."},{"id":"d","feedback":"نفس الـ charge مش معناه نفس الـ 3d: الـ $\\ce{Fe^{2+}}$ هو $3d^6$ مش $3d^5$."}],"explanation":"عدد الـ electrons: $\\ce{Fe^{3+}}$ 26 − 3 = 23، و$\\ce{Mn^{2+}}$ 25 − 2 = 23. الاتنين $[\\text{Ar}]\\ 3d^5$."},"tf":{"explanation":"السبب في الكتاب هو إن الـ 3d sublevel نصه مليان ($3d^5$)، مش حجم الـ charge.","feedback_true":"لو الـ charge الأكبر معناه استقرار أكتر، كان الـ $\\ce{Mn^{3+}}$ هيبقى أكتر استقرارًا من الـ $\\ce{Mn^{2+}}$، وده مش حاصل. السبب هو عدد الـ 3d، مش الـ charge.","feedback_false":"صح إنك رفضتها. السبب هو الـ $3d^5$ اللي نصه مليان في الـ $\\ce{Fe^{3+}}$، مش الـ charge بتاعه."}},"s7":{"o":{"items":[{"id":"a","feedback":"السطر ده هو configuration الذرة نفسها، $[\\text{Ar}]\\ 4s^2\\ 3d^6$، والـ ions بتيجي منها بعد ما تخسر electrons."},{"id":"b","feedback":"الـ $\\ce{Fe^{2+}}$ بيتكوّن لما الـ iron يخسر الاتنين 4s electrons، وده قبل ما يخسر أي 3d electron."},{"id":"c","feedback":"الـ $\\ce{Fe^{3+}}$ بيتكوّن من الـ $\\ce{Fe^{2+}}$ لما يخسر electron كمان."},{"id":"d","feedback":"الحكم على الاستقرار محتاج الـ configuration بتاعة الـ $\\ce{Fe^{3+}}$، يعني الـ $3d^5$، تكون اتكتبت قبله."},{"id":"e","feedback":"السطر ده هو النتيجة اللي بتطلع من الأسباب، مش سبب."}],"explanation":"الذرة → $\\ce{Fe^{2+}}$ → $\\ce{Fe^{3+}}$ → الـ $3d^5$ اللي نصه مليان أكتر استقرارًا → فالتفاعل بيمشي ناحية الـ $\\ce{Fe^{3+}}$."},"q":{"options":[{"id":"a","feedback":"صح: +2 لما يخسر الـ 4s²، و+3 مع الـ 3d⁵ المستقر اللي نصه مليان."},{"id":"b","feedback":"الـ iron عنده 8 electrons في الـ 4s والـ 3d، لكنه مابيوصلش لـ +8: أعلى state ليه +6."},{"id":"c","feedback":"الـ +3 مهمة فعلًا، لكنها مش الـ state المهمة الوحيدة للـ iron في الكتاب."},{"id":"d","feedback":"الـ +6 موجودة، في الـ $\\ce{Na2FeO4}$، لكن الكتاب بيقول إن كل الـ states اللي فوق +3 مش مهمة."}],"explanation":"الكتاب بيقول إن الـ oxidation states المهمة للـ iron هي +2 و+3: الـ +2 لما يخسر الاتنين 4s electrons، والـ +3 مع الـ $3d^5$ المستقر اللي نصه مليان. أما الـ states اللي فوق +3 فمش مهمة."}},"s8":{"exam":{"body":"الـ **Fe³⁺** ([Ar] 3d⁵) أكتر استقرارًا من الـ **Fe²⁺** ([Ar] 3d⁶) عشان الـ **3d sublevel بتاعه نصه مليان**. والـ **Mn²⁺** **نصه مليان أصلًا (3d⁵)**، فهو **أكتر استقرارًا من الـ Mn³⁺**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":4,"lesson_no":10,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-configuration","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Electronic configurations and oxidation states","duration_s":717.229,"start_s":264.6,"end_s":322.4,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.fe2-fe3-mn2-stability","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Iron(II) is easily oxidized while manganese(II) is not","duration_s":43.73,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"exercise":"Exercise","relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.oxidation-states-trend","kind":"lesson","version":2,"catalog_version":3,"ord":184,"primary_concept_id":"te.oxidation-states-trend","concepts":[{"concept_id":"te.oxidation-states-trend","role":"primary"}],"title":"Oxidation states from Sc to Zn","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"+12: it loses all its 4s and 3d electrons","correct":false},{"id":"b","text":"+2","correct":true},{"id":"c","text":"+7, like manganese","correct":false}],"question":"Predict: what is zinc's highest oxidation state in the book's table?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Manganese has 7 electrons in 4s and 3d, and it reaches +7 in $\\ce{KMnO4}$. Zinc has 12 electrons in 4s and 3d."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Twelve electrons, how many states?"},{"id":"s2","kind":"interact","spec":{"root":"root","state":{"z":21},"elements":{"n":{"type":"Text","props":{"muted":true,"content":"Book table, p.8 (for illustration only). Copper's row is printed with a typo; its states are +1 and +2."},"children":[]},"t":{"type":"Text","props":{"content":"Slide from Sc to Zn. For each element, compare the two numbers."},"children":[]},"sl":{"type":"Slider","props":{"max":30,"min":21,"step":1,"label":"atomic number Z","value":{"$bindState":"/z"}},"children":[]},"c21":{"type":"Card","props":{"tone":"info","title":"Sc (Z = 21), group IIIB"},"visible":{"eq":21,"$state":"/z"},"children":["c21a","c21s","c21b"]},"c22":{"type":"Card","props":{"tone":"info","title":"Ti (Z = 22), group IVB"},"visible":{"eq":22,"$state":"/z"},"children":["c22a","c22s","c22b"]},"c23":{"type":"Card","props":{"tone":"info","title":"V (Z = 23), group VB"},"visible":{"eq":23,"$state":"/z"},"children":["c23a","c23s","c23b"]},"c24":{"type":"Card","props":{"tone":"info","title":"Cr (Z = 24), group VIB"},"visible":{"eq":24,"$state":"/z"},"children":["c24a","c24s","c24b"]},"c25":{"type":"Card","props":{"tone":"info","title":"Mn (Z = 25), group VIIB"},"visible":{"eq":25,"$state":"/z"},"children":["c25a","c25s","c25b"]},"c26":{"type":"Card","props":{"tone":"info","title":"Fe (Z = 26), group VIII"},"visible":{"eq":26,"$state":"/z"},"children":["c26a","c26s","c26b"]},"c27":{"type":"Card","props":{"tone":"info","title":"Co (Z = 27), group VIII"},"visible":{"eq":27,"$state":"/z"},"children":["c27a","c27s","c27b"]},"c28":{"type":"Card","props":{"tone":"info","title":"Ni (Z = 28), group VIII"},"visible":{"eq":28,"$state":"/z"},"children":["c28a","c28s","c28b"]},"c29":{"type":"Card","props":{"tone":"info","title":"Cu (Z = 29), group IB"},"visible":{"eq":29,"$state":"/z"},"children":["c29a","c29s","c29b"]},"c30":{"type":"Card","props":{"tone":"info","title":"Zn (Z = 30), group IIB"},"visible":{"eq":30,"$state":"/z"},"children":["c30a","c30s","c30b"]},"c21a":{"type":"Text","props":{"content":"$[\\text{Ar}]\\ 4s^2\\ 3d^1$. Oxidation states: +3"},"children":[]},"c21b":{"type":"Text","props":{"muted":true,"content":"Compounds: $\\ce{Sc2O3}$"},"children":[]},"c21m":{"type":"Stat","props":{"tone":"warning","label":"highest oxidation state","value":"+3"},"children":[]},"c21n":{"type":"Stat","props":{"tone":"info","label":"electrons in 4s + 3d","value":3},"children":[]},"c21s":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["c21n","c21m"]},"c22a":{"type":"Text","props":{"content":"$[\\text{Ar}]\\ 4s^2\\ 3d^2$. Oxidation states: +2, +3, +4"},"children":[]},"c22b":{"type":"Text","props":{"muted":true,"content":"Compounds: $\\ce{TiO2}$, $\\ce{Ti2O3}$, $\\ce{TiO}$"},"children":[]},"c22m":{"type":"Stat","props":{"tone":"warning","label":"highest oxidation state","value":"+4"},"children":[]},"c22n":{"type":"Stat","props":{"tone":"info","label":"electrons in 4s + 3d","value":4},"children":[]},"c22s":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["c22n","c22m"]},"c23a":{"type":"Text","props":{"content":"$[\\text{Ar}]\\ 4s^2\\ 3d^3$. Oxidation states: +2, +3, +4, +5"},"children":[]},"c23b":{"type":"Text","props":{"muted":true,"content":"Compounds: $\\ce{V2O5}$, $\\ce{VO2}$, $\\ce{V2O3}$, $\\ce{VO}$"},"children":[]},"c23m":{"type":"Stat","props":{"tone":"warning","label":"highest oxidation state","value":"+5"},"children":[]},"c23n":{"type":"Stat","props":{"tone":"info","label":"electrons in 4s + 3d","value":5},"children":[]},"c23s":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["c23n","c23m"]},"c24a":{"type":"Text","props":{"content":"$[\\text{Ar}]\\ 4s^1\\ 3d^5$. Oxidation states: +2, +3, +6"},"children":[]},"c24b":{"type":"Text","props":{"muted":true,"content":"Compounds: $\\ce{CrO3}$, $\\ce{Cr2O3}$, $\\ce{CrO}$"},"children":[]},"c24m":{"type":"Stat","props":{"tone":"warning","label":"highest oxidation state","value":"+6"},"children":[]},"c24n":{"type":"Stat","props":{"tone":"info","label":"electrons in 4s + 3d","value":6},"children":[]},"c24s":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["c24n","c24m"]},"c25a":{"type":"Text","props":{"content":"$[\\text{Ar}]\\ 4s^2\\ 3d^5$. Oxidation states: +2, +3, +4, +6, +7"},"children":[]},"c25b":{"type":"Text","props":{"muted":true,"content":"Compounds: $\\ce{KMnO4}$, $\\ce{K2MnO4}$, $\\ce{MnO2}$, $\\ce{Mn2O3}$, $\\ce{MnO}$"},"children":[]},"c25m":{"type":"Stat","props":{"tone":"warning","label":"highest oxidation state","value":"+7"},"children":[]},"c25n":{"type":"Stat","props":{"tone":"info","label":"electrons in 4s + 3d","value":7},"children":[]},"c25s":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["c25n","c25m"]},"c26a":{"type":"Text","props":{"content":"$[\\text{Ar}]\\ 4s^2\\ 3d^6$. Oxidation states: +2, +3, +6"},"children":[]},"c26b":{"type":"Text","props":{"muted":true,"content":"Compounds: $\\ce{Na2FeO4}$, $\\ce{Fe2O3}$, $\\ce{FeO}$"},"children":[]},"c26m":{"type":"Stat","props":{"tone":"warning","label":"highest oxidation state","value":"+6"},"children":[]},"c26n":{"type":"Stat","props":{"tone":"info","label":"electrons in 4s + 3d","value":8},"children":[]},"c26s":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["c26n","c26m"]},"c27a":{"type":"Text","props":{"content":"$[\\text{Ar}]\\ 4s^2\\ 3d^7$. Oxidation states: +2, +3, +4"},"children":[]},"c27b":{"type":"Text","props":{"muted":true,"content":"Compounds: $\\ce{CoCl3}$, $\\ce{CoCl2}$"},"children":[]},"c27m":{"type":"Stat","props":{"tone":"warning","label":"highest oxidation state","value":"+4"},"children":[]},"c27n":{"type":"Stat","props":{"tone":"info","label":"electrons in 4s + 3d","value":9},"children":[]},"c27s":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["c27n","c27m"]},"c28a":{"type":"Text","props":{"content":"$[\\text{Ar}]\\ 4s^2\\ 3d^8$. Oxidation states: +2, +3, +4"},"children":[]},"c28b":{"type":"Text","props":{"muted":true,"content":"Compounds: $\\ce{NiO2}$, $\\ce{Ni2O3}$, $\\ce{NiO}$"},"children":[]},"c28m":{"type":"Stat","props":{"tone":"warning","label":"highest oxidation state","value":"+4"},"children":[]},"c28n":{"type":"Stat","props":{"tone":"info","label":"electrons in 4s + 3d","value":10},"children":[]},"c28s":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["c28n","c28m"]},"c29a":{"type":"Text","props":{"content":"$[\\text{Ar}]\\ 4s^1\\ 3d^{10}$. Oxidation states: +1, +2"},"children":[]},"c29b":{"type":"Text","props":{"muted":true,"content":"Compounds: $\\ce{CuO}$, $\\ce{Cu2O}$"},"children":[]},"c29m":{"type":"Stat","props":{"tone":"warning","label":"highest oxidation state","value":"+2"},"children":[]},"c29n":{"type":"Stat","props":{"tone":"info","label":"electrons in 4s + 3d","value":11},"children":[]},"c29s":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["c29n","c29m"]},"c30a":{"type":"Text","props":{"content":"$[\\text{Ar}]\\ 4s^2\\ 3d^{10}$. Oxidation states: +2"},"children":[]},"c30b":{"type":"Text","props":{"muted":true,"content":"Compounds: $\\ce{ZnO}$"},"children":[]},"c30m":{"type":"Stat","props":{"tone":"warning","label":"highest oxidation state","value":"+2"},"children":[]},"c30n":{"type":"Stat","props":{"tone":"info","label":"electrons in 4s + 3d","value":12},"children":[]},"c30s":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["c30n","c30m"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","c21","c22","c23","c24","c25","c26","c27","c28","c29","c30","n"]}}},"title":"Walk the book's table"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"ch":{"type":"Chart","props":{"kind":"line","series":[{"name":"Electrons in 4s + 3d","points":[{"x":"Sc","y":3},{"x":"Ti","y":4},{"x":"V","y":5},{"x":"Cr","y":6},{"x":"Mn","y":7},{"x":"Fe","y":8},{"x":"Co","y":9},{"x":"Ni","y":10},{"x":"Cu","y":11},{"x":"Zn","y":12}]},{"name":"Highest oxidation state","points":[{"x":"Sc","y":3},{"x":"Ti","y":4},{"x":"V","y":5},{"x":"Cr","y":6},{"x":"Mn","y":7},{"x":"Fe","y":6},{"x":"Co","y":4},{"x":"Ni","y":4},{"x":"Cu","y":2},{"x":"Zn","y":2}]}],"caption":"The two lines match from Sc to Mn, then split","x_label":"Element","y_label":"Number","annotations":[{"x":"Mn","text":"+7, the highest"}]},"children":[]},"t1":{"type":"Text","props":{"content":"From Sc to Mn, the highest state uses all the 4s and 3d electrons."},"children":[]},"t2":{"type":"Text","props":{"content":"After Mn, the highest state decreases gradually, to +2 in zinc."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["ch","t1","t2","m"]}}},"title":"Up to Mn, then down"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"In $\\ce{Na2FeO4}$ (Na = +1, O = −2), iron is ___ .","answers":[["+6","6","+ 6"]],"mistakes":[{"id":"m1","blank":0,"answer":"+8"},{"id":"m2","blank":0,"answer":"8"},{"id":"m3","blank":0,"answer":"+3"},{"id":"m4","blank":0,"answer":"3"},{"id":"m5","blank":0,"answer":"+10"},{"id":"m6","blank":0,"answer":"10"},{"id":"m7","blank":0,"answer":"-6"},{"id":"m8","blank":0,"answer":"−6"}]},"children":[]},"h":{"type":"Heading","props":{"text":"Your turn: iron in Na₂FeO₄","level":3},"children":[]},"t":{"type":"Text","props":{"content":"The table lists compounds. Find each metal's oxidation state with the sum-to-zero rule."},"children":[]},"hl":{"type":"HintLadder","props":{},"children":[]},"r1":{"type":"Reveal","props":{"label":"Worked: vanadium in V₂O₅"},"children":["r1t","r1f","r1c"]},"r1c":{"type":"Text","props":{"content":"+5 is vanadium's highest state: it has lost all 5 of its 4s and 3d electrons."},"children":[]},"r1f":{"type":"Formula","props":{"latex":"2x + 5(-2) = 0 \\;\\Rightarrow\\; 2x = +10 \\;\\Rightarrow\\; x = +5"},"children":[]},"r1t":{"type":"Text","props":{"content":"Call vanadium x. Two V atoms give 2x; five O atoms give 5 × (−2)."},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["t","r1","h","f","hl"]}}},"title":"Read a state from a formula"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Callout","props":{"variant":"info"},"children":[]},"t":{"type":"Text","props":{"content":"Book point 4: the maximum oxidation state does not exceed the group number. Group VIII stays well below 8."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["IIIB to VIIB","Sc, Ti, V, Cr, Mn","+3, +4, +5, +6, +7"],["VIII","Fe, Co, Ni","+6, +4, +4"],["IB","Cu","+2"],["IIB","Zn","+2"]],"caption":"Highest oxidation states by group (book table, p.8)","headers":["Group","Elements","Highest state"],"highlight":[{"col":2,"row":2}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tb","t","c"]}}},"title":"The group number limit"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":1}],"caption":"$[\\text{Ar}]\\ 4s^2\\ 3d^1$","show_unpaired":true},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":0}],"caption":"$[\\text{Ar}]$: 4s and 3d are empty"},"children":[]},"c1":{"type":"Card","props":{"title":"Sc atom"},"children":["b1"]},"c2":{"type":"Card","props":{"tone":"success","title":"Sc³⁺"},"children":["b2"]},"t1":{"type":"Text","props":{"content":"Scandium has only three electrons in 4s and 3d. $\\ce{Sc^{3+}}$ has lost all three."},"children":[]},"t2":{"type":"Text","props":{"content":"$\\ce{Sc^{3+}}$ has the stable configuration of argon. A fourth electron would have to come from that stable arrangement."},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["cols","t1","t2","exam"]}}},"title":"Why no Sc⁴⁺?"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"In $\\ce{K2Cr2O7}$, chromium is ___ . This is ___ its group number (type: below / equal to / above).","answers":[["+6","6","+ 6"],["equal to","equal","equals"]],"mistakes":[{"id":"m1","blank":0,"answer":"+12"},{"id":"m2","blank":0,"answer":"12"},{"id":"m3","blank":0,"answer":"+7"},{"id":"m4","blank":0,"answer":"7"},{"id":"m5","blank":0,"answer":"-6"},{"id":"m6","blank":0,"answer":"−6"},{"id":"m7","blank":1,"answer":"below"},{"id":"m8","blank":1,"answer":"above"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"+6","correct":true},{"id":"b","text":"+7","correct":false},{"id":"c","text":"+2","correct":false},{"id":"d","text":"+4","correct":false}],"question":"Molybdenum (Mo) is below chromium, in group VIB. By the book's rule, its highest oxidation state cannot exceed:"},"children":[]},"hl":{"type":"HintLadder","props":{},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","f","hl"]}}},"title":"Use the rules"},{"id":"s8","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Group IB is the book's exception: its maximum can exceed the group number","correct":true},{"id":"b","text":"The value must be a mistake","correct":false},{"id":"c","text":"Gold is not in the first series, so the book's rule says nothing","correct":false},{"id":"d","text":"The maximum always equals the group number","correct":false}],"question":"In $\\ce{AuCl3}$, gold is +3. Gold is in group IB. What does this show?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":true,"statement":"Titanium does not form $\\ce{Ti^{5+}}$ for the same reason that scandium does not form $\\ce{Sc^{4+}}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Gold and titanium"},{"id":"s9","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["The highest state rises from Sc (+3) to Mn (+7), then decreases to Zn (+2). Zinc has 12 electrons in 4s and 3d, yet only +2.","From Sc to Mn it equals the number of 4s and 3d electrons. After Mn it is lower: Fe +6, Co and Ni +4.","The maximum does not exceed the group number, except group IB (Cu shows +2).","$\\ce{Sc^{3+}}$ is [Ar], so there is no $\\ce{Sc^{4+}}$."]},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"Vanadium is $[\\text{Ar}]\\ 4s^2\\ 3d^3$: it has 5 electrons in 4s and 3d. At +5 it has lost all of them, and +5 is also its group number (VB). So its highest state is +5."},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why vanadium's highest state is +5 and not +6?"},"children":[]}}},"title":"Summary"}],"title":"Oxidation states from Sc to Zn","minutes":9,"book_ref":"Ch.1 The Electronic Configurations and Oxidation states: table and point 4, pp.8-9; Evaluation Q7.8, p.27","subtitle":"Up to manganese, then down","objectives":["Read the oxidation states of Sc to Zn from the book's table, and find a metal's oxidation state from a formula (e.g. $\\ce{V2O5}$: +5).","Describe the trend: the highest oxidation state rises from Sc (+3) to Mn (+7), then falls to Zn (+2).","State that the maximum oxidation state does not exceed the group number, except in group IB (Cu, Ag, Au).","Explain why scandium does not form $\\ce{Sc^{4+}}$."],"concept_ids":["te.oxidation-states-trend"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"That extends manganese's pattern to zinc, but the pattern does not hold after Mn, as the table shows."},{"id":"b","feedback":"Yes. Zinc shows only +2. The highest state rises up to Mn, then falls."},{"id":"c","feedback":"Mn's +7 matches its own 7 electrons in 4s and 3d, so zinc has no reason to stop at Mn's number."}],"explanation":"Zinc's highest oxidation state in the table is +2. The highest state rises from Sc up to Mn (+7), then decreases gradually to +2 in zinc."}},"s3":{"m":{"statement":"The highest oxidation state always equals the number of 4s and 3d electrons, for every element.","correction":"That holds only from Sc to Mn. Iron does not reach +8: it stops at +6."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"That counts iron's 4s and 3d electrons. The state comes from the formula: 2 Na give +2 and 4 O give −8."},{"id":"m2","feedback":"That counts iron's 4s and 3d electrons. The state comes from the formula: 2 Na give +2 and 4 O give −8."},{"id":"m3","feedback":"That is iron in $\\ce{Fe2O3}$. Here the state comes from adding up the 2 Na and the 4 O."},{"id":"m4","feedback":"That is iron in $\\ce{Fe2O3}$. Here the state comes from adding up the 2 Na and the 4 O."},{"id":"m5","feedback":"Sodium counts as +1, not −1."},{"id":"m6","feedback":"Sodium counts as +1, not −1."},{"id":"m7","feedback":"The O atoms give a negative total, so iron must be positive to cancel it."},{"id":"m8","feedback":"The O atoms give a negative total, so iron must be positive to cancel it."}],"explanation":"2(+1) + x + 4(−2) = 0, so x = +6. Iron's highest state is +6, not +8."},"hl":{"hints":["Two Na atoms give +2.","Four O atoms give −8.","+2 + x − 8 must equal 0."]}},"s5":{"c":{"body":"Group IB (copper, silver and gold) is the exception. Copper shows +2, above its group number (I).","title":"The exception"}},"s6":{"exam":{"body":"Because **$\\ce{Sc^{3+}}$** has the **stable configuration of argon, [Ar]**: its 4s and 3d are empty. Losing another electron would break this stable arrangement.","title":"Give reasons: scandium doesn't produce Sc⁴⁺"}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"You gave the whole positive total to one Cr atom, but two Cr atoms share it."},{"id":"m2","feedback":"You gave the whole positive total to one Cr atom, but two Cr atoms share it."},{"id":"m3","feedback":"The two K atoms add +2 to the sum, and they are missing here."},{"id":"m4","feedback":"The two K atoms add +2 to the sum, and they are missing here."},{"id":"m5","feedback":"Seven O atoms give a negative total, so Cr must be positive."},{"id":"m6","feedback":"Seven O atoms give a negative total, so Cr must be positive."},{"id":"m7","feedback":"Chromium is in group VIB, and its state here is not below VI."},{"id":"m8","feedback":"Chromium is in group VIB, and its state here is not above VI."}],"explanation":"2(+1) + 2x + 7(−2) = 0, so x = +6. That equals its group number (VIB)."},"q":{"options":[{"id":"a","feedback":"Right: the maximum does not exceed the group number, VI. Mo does reach +6, in $\\ce{MoO3}$."},{"id":"b","feedback":"+7 belongs to group VIIB, like manganese, and Mo is not in group VIIB."},{"id":"c","feedback":"Most of the first series shows +2, but that is a low state; the group number limits the highest state."},{"id":"d","feedback":"+4 is where Co and Ni stop, in group VIII, and Mo is not in group VIII."}],"explanation":"Group VIB → the maximum cannot exceed +6."},"hl":{"hints":["K counts +1 and O counts −2.","Two K give +2; seven O give −14.","Two Cr atoms share the rest."]}},"s8":{"q":{"options":[{"id":"a","feedback":"Right. Copper, silver and gold can go above their group number (I)."},{"id":"b","feedback":"Gold's +3 in $\\ce{AuCl3}$ is real, so it is not a mistake."},{"id":"c","feedback":"The book's rule names copper, silver and gold together, so gold is covered."},{"id":"d","feedback":"Then gold would stop at +1, and its +3 does not fit that; Fe, Co and Ni do not reach their group number either."}],"explanation":"It shows the book's exception: the maximum oxidation state does not exceed the group number except in group IB (copper, silver and gold). Gold, in group IB, reaches +3."},"tf":{"explanation":"Ti: $[\\text{Ar}]\\ 4s^2\\ 3d^2$. $\\ce{Ti^{4+}}$ = [Ar], the same stable arrangement as $\\ce{Sc^{3+}}$.","feedback_true":"Right. $\\ce{Ti^{4+}}$ is already [Ar], so a fifth electron would have to break the stable argon arrangement.","feedback_false":"Titanium is $[\\text{Ar}]\\ 4s^2\\ 3d^2$, so once $\\ce{Ti^{4+}}$ forms, nothing is left in 4s and 3d: the same stable arrangement as $\\ce{Sc^{3+}}$."}},"s9":{"exam":{"body":"States **increase from Sc to Mn (+7)**, then **decrease to +2 in Zn**. The maximum **does not exceed the group number, except group IB**.","title":"Book point 4"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"كده إنت مدّيت نمط الـ manganese لحد الـ zinc، لكن الجدول بيوضّح إن أعلى state بيطلع لحد الـ Mn وبعدين بيقل."},{"id":"b","feedback":"أيوه. الـ zinc بيدي +2 لوحده. أعلى state بيطلع لحد الـ Mn، وبعدين ينزل."},{"id":"c","feedback":"الـ +7 بتاع الـ Mn ماشي مع الـ 7 electrons بتوعه هو في الـ 4s والـ 3d، فمفيش سبب يخلّي الـ zinc يقف عند رقم الـ Mn."}],"explanation":"أعلى oxidation state للـ zinc في الجدول هو +2. أعلى state بيزيد من الـ Sc لحد الـ Mn (+7)، وبعدين بيقل بالتدريج لحد +2 في الـ zinc."}},"s3":{"m":{"statement":"أعلى oxidation state لأي element بيساوي عدد الـ electrons اللي في الـ 4s والـ 3d.","correction":"ده بيمشي من الـ Sc لحد الـ Mn وبس. الـ iron مش بيوصل لـ +8: بيقف عند +6."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"كده إنت عدّيت الـ electrons اللي في الـ 4s والـ 3d بتاعة الـ iron، لكن الـ oxidation state بيتحسب من الصيغة: الـ 2 Na والـ 4 O مع الـ iron مجموعهم صفر."},{"id":"m2","feedback":"كده إنت عدّيت الـ electrons اللي في الـ 4s والـ 3d بتاعة الـ iron، لكن الـ oxidation state بيتحسب من الصيغة: الـ 2 Na والـ 4 O مع الـ iron مجموعهم صفر."},{"id":"m3","feedback":"دي حالة الـ iron في $\\ce{Fe2O3}$، لكن هنا الحساب من الـ 2 Na والـ 4 O اللي في الصيغة دي."},{"id":"m4","feedback":"دي حالة الـ iron في $\\ce{Fe2O3}$، لكن هنا الحساب من الـ 2 Na والـ 4 O اللي في الصيغة دي."},{"id":"m5","feedback":"الـ Na بيتحسب +1، مش −1."},{"id":"m6","feedback":"الـ Na بيتحسب +1، مش −1."},{"id":"m7","feedback":"الـ O بيدي مجموع سالب، فالـ iron لازم إشارته موجبة عشان يلغيه."},{"id":"m8","feedback":"الـ O بيدي مجموع سالب، فالـ iron لازم إشارته موجبة عشان يلغيه."}],"explanation":"2(+1) + x + 4(−2) = 0، يعني x = +6. أعلى state للـ iron هو +6، مش +8."},"hl":{"hints":["ذرتين الـ Na بيدوا +2.","أربع ذرات O بيدوا −8.","+2 + x − 8 لازم تساوي 0."]}},"s5":{"c":{"body":"الـ group IB (الـ copper والـ silver والـ gold) هي الاستثناء. الـ copper بيدّي +2، أعلى من رقم الـ group بتاعه (I).","title":"الاستثناء"}},"s6":{"exam":{"body":"عشان **$\\ce{Sc^{3+}}$** عنده **الـ configuration المستقرة بتاعة الـ argon، [Ar]**: الـ 4s والـ 3d عنده فاضيين. لو فقد electron كمان هيكسر الترتيب المستقر ده.","title":"علّل: الـ scandium مش بيكوّن Sc⁴⁺"}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"إنت إديت المجموع الموجب كله لذرة Cr واحدة، لكن الصيغة فيها ذرتين Cr بيتقسموه."},{"id":"m2","feedback":"إنت إديت المجموع الموجب كله لذرة Cr واحدة، لكن الصيغة فيها ذرتين Cr بيتقسموه."},{"id":"m3","feedback":"إنت ماحسبتش ذرتين الـ K، واللي بيزوّدوا +2 على المجموع."},{"id":"m4","feedback":"إنت ماحسبتش ذرتين الـ K، واللي بيزوّدوا +2 على المجموع."},{"id":"m5","feedback":"سبع ذرات O بيدوا مجموع سالب، فالـ Cr لازم إشارته موجبة."},{"id":"m6","feedback":"سبع ذرات O بيدوا مجموع سالب، فالـ Cr لازم إشارته موجبة."},{"id":"m7","feedback":"الـ chromium في group VIB، والمقارنة هنا بين رقم الـ group ده والـ oxidation state اللي في الفراغ الأول."},{"id":"m8","feedback":"الـ chromium في group VIB، والمقارنة هنا بين رقم الـ group ده والـ oxidation state اللي في الفراغ الأول."}],"explanation":"2(+1) + 2x + 7(−2) = 0، يعني x = +6. وده بيساوي رقم الـ group بتاعه (VIB)."},"q":{"options":[{"id":"a","feedback":"صح: أعلى state مابيعديش رقم الـ group، اللي هو VI. والـ Mo فعلًا بيوصل لـ +6، في $\\ce{MoO3}$."},{"id":"b","feedback":"الـ +7 ده بتاع group VIIB، زي الـ manganese، والـ Mo في group VIB."},{"id":"c","feedback":"معظم الـ first series بيدي +2، لكن ده state واطي، وأعلى state بيحدده رقم الـ group."},{"id":"d","feedback":"الـ +4 ده المكان اللي الـ Co والـ Ni بيقفوا عنده، في group VIII، والـ Mo مش في group VIII."}],"explanation":"الـ group هو VIB، يبقى أعلى state مايعديش +6."},"hl":{"hints":["الـ K بيتحسب +1 والـ O بيتحسب −2.","ذرتين K بيدوا +2، وسبع ذرات O بيدوا −14.","ذرتين الـ Cr بيتقسموا الباقي."]}},"s8":{"q":{"options":[{"id":"a","feedback":"صح. الـ copper والـ silver والـ gold ممكن يعدّوا رقم الـ group بتاعهم (I)."},{"id":"b","feedback":"الـ +3 بتاع الـ gold في الـ $\\ce{AuCl3}$ حقيقي، والكتاب بيذكر group بعينه كاستثناء للقاعدة."},{"id":"c","feedback":"قاعدة الكتاب بتذكر الـ copper والـ silver والـ gold مع بعض، فالـ gold داخل فيها."},{"id":"d","feedback":"لو كده كان الـ gold وقف عند +1، والـ +3 مش ماشي مع ده. والـ Fe والـ Co والـ Ni أعلى state ليهم أقل من رقم الـ group بتاعهم."}],"explanation":"ده بيوضّح استثناء الكتاب: أقصى oxidation state مش بيعدّي رقم الـ group إلا في الـ group IB (الـ copper والـ silver والـ gold). والـ gold، اللي في الـ group IB، بيوصل لـ +3."},"tf":{"explanation":"الـ Ti: $[\\text{Ar}]\\ 4s^2\\ 3d^2$. والـ $\\ce{Ti^{4+}}$ = [Ar]، نفس الترتيب المستقر بتاع الـ $\\ce{Sc^{3+}}$.","feedback_true":"صح. الـ $\\ce{Ti^{4+}}$ هو أصلًا [Ar]، فأي electron خامس هيضطر يكسر ترتيب الـ argon المستقر.","feedback_false":"الـ titanium هو $[\\text{Ar}]\\ 4s^2\\ 3d^2$، يعني عنده 4 electrons في الـ 4s والـ 3d، فلما الـ $\\ce{Ti^{4+}}$ يتكوّن مابيفضلش حاجة في الـ 4s والـ 3d، وده نفس ترتيب الـ $\\ce{Sc^{3+}}$ المستقر."}},"s9":{"exam":{"body":"الـ states **بتزيد من الـ Sc لحد الـ Mn (+7)**، وبعدين **بتقل لحد +2 في الـ Zn**. الـ maximum **مش بيعدّي رقم الـ group، ما عدا الـ group IB**.","title":"النقطة 4 في الكتاب"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":5,"lesson_no":11,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-configuration","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Electronic configurations and oxidation states","duration_s":717.229,"start_s":329.7,"end_s":390.8,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.oxidation-states-trend","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Oxidation states from Sc to Zn","duration_s":52.24,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"8","relation":"based_on"}]},{"id":"chem-s3-en.lesson-pt.atomic-radius-trend","kind":"lesson","version":2,"catalog_version":3,"ord":186,"primary_concept_id":"pt.atomic-radius-trend","concepts":[{"concept_id":"pt.atomic-radius-trend","role":"primary"}],"title":"Atomic radius trend","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Sodium","correct":true},{"id":"b","text":"Chlorine, because it has more electrons","correct":false},{"id":"c","text":"Same size: both use three main levels","correct":false}],"question":"Predict: which atom is larger?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Sodium (Z = 11) and chlorine (Z = 17) are both in period 3. Chlorine has six more electrons."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"More electrons, bigger atom?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"ch":{"type":"Chart","props":{"kind":"bar","unit":"Å","series":[{"name":"Atomic radius","points":[{"x":"Na","y":1.86},{"x":"Mg","y":1.6},{"x":"Al","y":1.43},{"x":"Si","y":1.18},{"x":"P","y":1.1},{"x":"S","y":1.04},{"x":"Cl","y":0.99}]}],"caption":"Typical atomic radii across period 3, in Å (1 Å = $10^{-10}$ m)","x_label":"Period 3 (left to right)","y_label":"Atomic radius"},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Atomic radius","definition":"Half the distance between the nuclei of two identical atoms bonded together."},"children":[]},"t1":{"type":"Text","props":{"content":"From Na to Cl, each atom adds one proton and one electron. The new electron enters the same outer level (n = 3)."},"children":[]},"t2":{"type":"Text","props":{"content":"More protons pull that level harder. So the radius decreases across the period."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["kt","ch","t1","t2"]}}},"title":"Across a period: a stronger pull"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"p":2},"elements":{"c":{"type":"Callout","props":{"variant":"tip"},"visible":{"eq":5,"$state":"/p"},"children":[]},"t":{"type":"Text","props":{"content":"Move down group IA, from Li to Rb. Watch the occupied main energy levels."},"children":[]},"d2":{"type":"Diagram","props":{"svg":"<svg viewBox=\"-10 -26 360 370\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"170\" cy=\"170\" r=\"47.1\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-opacity=\"0.6\"/><circle cx=\"170\" cy=\"170\" r=\"94.2\" fill=\"none\" stroke=\"#fbbf24\" stroke-width=\"2.5\" stroke-opacity=\"1\"/><circle cx=\"170\" cy=\"170\" r=\"8\" fill=\"#f87171\"/><circle cx=\"264.2\" cy=\"170\" r=\"6.5\" fill=\"#60a5fa\"/><text x=\"170\" y=\"67.8\" text-anchor=\"middle\" font-size=\"16\" font-weight=\"700\" fill=\"#e2e8f0\">Li</text></svg>","caption":"Li: 2 main levels, radius 1.52 Å","max_width":300},"visible":{"eq":2,"$state":"/p"},"children":[]},"d3":{"type":"Diagram","props":{"svg":"<svg viewBox=\"-10 -26 360 370\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"170\" cy=\"170\" r=\"38.4\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-opacity=\"0.6\"/><circle cx=\"170\" cy=\"170\" r=\"76.9\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-opacity=\"0.6\"/><circle cx=\"170\" cy=\"170\" r=\"115.3\" fill=\"none\" stroke=\"#fbbf24\" stroke-width=\"2.5\" stroke-opacity=\"1\"/><circle cx=\"170\" cy=\"170\" r=\"8\" fill=\"#f87171\"/><circle cx=\"285.3\" cy=\"170\" r=\"6.5\" fill=\"#60a5fa\"/><text x=\"170\" y=\"46.7\" text-anchor=\"middle\" font-size=\"16\" font-weight=\"700\" fill=\"#e2e8f0\">Na</text></svg>","caption":"Na: 3 main levels, radius 1.86 Å","max_width":300},"visible":{"eq":3,"$state":"/p"},"children":[]},"d4":{"type":"Diagram","props":{"svg":"<svg viewBox=\"-10 -26 360 370\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"170\" cy=\"170\" r=\"35.2\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-opacity=\"0.6\"/><circle cx=\"170\" cy=\"170\" r=\"70.4\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-opacity=\"0.6\"/><circle cx=\"170\" cy=\"170\" r=\"105.6\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-opacity=\"0.6\"/><circle cx=\"170\" cy=\"170\" r=\"140.7\" fill=\"none\" stroke=\"#fbbf24\" stroke-width=\"2.5\" stroke-opacity=\"1\"/><circle cx=\"170\" cy=\"170\" r=\"8\" fill=\"#f87171\"/><circle cx=\"310.7\" cy=\"170\" r=\"6.5\" fill=\"#60a5fa\"/><text x=\"170\" y=\"21.3\" text-anchor=\"middle\" font-size=\"16\" font-weight=\"700\" fill=\"#e2e8f0\">K</text></svg>","caption":"K: 4 main levels, radius 2.27 Å","max_width":300},"visible":{"eq":4,"$state":"/p"},"children":[]},"d5":{"type":"Diagram","props":{"svg":"<svg viewBox=\"-10 -26 360 370\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"170\" cy=\"170\" r=\"30.8\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-opacity=\"0.6\"/><circle cx=\"170\" cy=\"170\" r=\"61.5\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-opacity=\"0.6\"/><circle cx=\"170\" cy=\"170\" r=\"92.3\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-opacity=\"0.6\"/><circle cx=\"170\" cy=\"170\" r=\"123.0\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-opacity=\"0.6\"/><circle cx=\"170\" cy=\"170\" r=\"153.8\" fill=\"none\" stroke=\"#fbbf24\" stroke-width=\"2.5\" stroke-opacity=\"1\"/><circle cx=\"170\" cy=\"170\" r=\"8\" fill=\"#f87171\"/><circle cx=\"323.8\" cy=\"170\" r=\"6.5\" fill=\"#60a5fa\"/><text x=\"170\" y=\"8.2\" text-anchor=\"middle\" font-size=\"16\" font-weight=\"700\" fill=\"#e2e8f0\">Rb</text></svg>","caption":"Rb: 5 main levels, radius 2.48 Å","max_width":300},"visible":{"eq":5,"$state":"/p"},"children":[]},"lv":{"type":"Stat","props":{"tone":"info","label":"occupied main levels","value":{"args":{"p":{"$state":"/p"},"expr":"p","digits":0},"$computed":"calc"}},"children":[]},"r2":{"type":"Stat","props":{"tone":"warning","label":"radius of Li","value":"1.52 Å"},"visible":{"eq":2,"$state":"/p"},"children":[]},"r3":{"type":"Stat","props":{"tone":"warning","label":"radius of Na","value":"1.86 Å"},"visible":{"eq":3,"$state":"/p"},"children":[]},"r4":{"type":"Stat","props":{"tone":"warning","label":"radius of K","value":"2.27 Å"},"visible":{"eq":4,"$state":"/p"},"children":[]},"r5":{"type":"Stat","props":{"tone":"warning","label":"radius of Rb","value":"2.48 Å"},"visible":{"eq":5,"$state":"/p"},"children":[]},"sl":{"type":"Slider","props":{"max":5,"min":2,"step":1,"label":"period","value":{"$bindState":"/p"}},"children":[]},"st":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["lv","r2","r3","r4","r5"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","st","d2","d3","d4","d5","c"]}}},"title":"Down a group: more levels"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"r":{"type":"Text","props":{"muted":true,"content":"Remember: like charges repel. All electrons are negative, so they push each other apart."},"children":[]},"t":{"type":"Text","props":{"content":"Size is a balance of the two. Across period 3, the pull wins, so the radius decreases."},"children":[]},"c1":{"type":"Card","props":{"tone":"info","title":"Pulls in: the nucleus"},"children":["c1t"]},"c2":{"type":"Card","props":{"tone":"warning","title":"Pushes out: repulsion"},"children":["c2t"]},"tb":{"type":"DataTable","props":{"rows":[["Pull of the nucleus (more protons)","decreases it"],["Repulsion between electrons (more electrons)","increases it"],["Across period 3","the pull wins: the radius decreases"]],"headers":["Factor","Effect on the radius"]},"children":[]},"c1t":{"type":"Text","props":{"content":"More protons attract the electrons more strongly. This decreases the radius."},"children":[]},"c2t":{"type":"Text","props":{"content":"More electrons repel each other more. This increases the radius."},"children":[]},"cols":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["r","cols","tb","t"]}}},"title":"Two opposite factors"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"o":{"type":"Ordering","props":{"items":[{"id":"li","text":"Li (Z = 3)"},{"id":"b","text":"B (Z = 5)"},{"id":"n","text":"N (Z = 7)"},{"id":"f","text":"F (Z = 9)"}],"prompt":"Order these period 2 atoms from the largest radius to the smallest."},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Bromine: its outer electrons are in an extra main level, farther from the nucleus","correct":true},{"id":"b","text":"Chlorine: it has fewer protons, so a weaker pull","correct":false},{"id":"c","text":"Bromine: it has more protons","correct":false},{"id":"d","text":"Same size: same group","correct":false}],"question":"Bromine (period 4) and chlorine (period 3) are both in group VIIA. Which is larger, and why?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o","q"]}}},"title":"Your turn"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Across a period, the radius decreases: more protons pull the same outer level harder.","Down a group, the radius increases: each period adds one main energy level.","Two opposite factors: the nucleus pulls electrons in; repulsion between electrons pushes them apart."]},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"From Na to Cl, each new electron enters the same outer level (n = 3), while the protons increase. The pull of the nucleus wins over the repulsion between electrons, so chlorine is smaller."},"children":[]},"next":{"type":"Text","props":{"muted":true,"content":"Next in Chapter 1: from Sc to Cu, both factors grow together. You will see what that does to the radius."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","next","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why chlorine is smaller than sodium, though it has more electrons?"},"children":[]}}},"title":"Summary"}],"title":"Atomic radius trend","minutes":5,"book_ref":"Background for Ch.1 General properties: atomic radius, pp.12-13 (two opposite factors)","subtitle":"Why atoms shrink across a period and grow down a group","objectives":["Describe the trend: across a period the atomic radius decreases; down a group it increases.","Explain it with the attraction of the nucleus (more protons, same level) and the number of main energy levels.","Name the two opposite factors: the nucleus pulls electrons in; repulsion between electrons pushes them apart."],"concept_ids":["pt.atomic-radius-trend"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Yes. A sodium atom is nearly twice as wide as a chlorine atom. This lesson shows why."},{"id":"b","feedback":"More electrons sounds bigger, but chlorine also has more protons pulling, and in the same level that pull wins."},{"id":"c","feedback":"Same number of levels, yes, but chlorine has six more protons, so the pull on those levels is not the same."}],"explanation":"Sodium is the larger atom. Both atoms use three main levels, but chlorine has six more protons pulling the electrons of the same level closer, so its radius is smaller."}},"s3":{"c":{"body":"Each period down adds one main energy level. The outer electron is farther from the nucleus, so the atom is larger.","title":"Down a group"}},"s5":{"o":{"items":[{"id":"li","feedback":"Li has the fewest protons here, so its pull on level n = 2 is the weakest."},{"id":"b","feedback":"All four use the same outer level, and B has fewer protons pulling than N."},{"id":"n","feedback":"N has more protons than B and fewer than F, so its pull lies between theirs."},{"id":"f","feedback":"F has the most protons here, so its pull on level n = 2 is the strongest."}],"explanation":"Same outer level (n = 2), more protons from Li to F: Li > B > N > F."},"q":{"options":[{"id":"a","feedback":"Right. One more period means one more main level, so the radius increases."},{"id":"b","feedback":"Protons decide the size within one level, but down a group a new main level is added each period."},{"id":"c","feedback":"More protons pull harder, which makes an atom smaller, not larger."},{"id":"d","feedback":"The same group means the same number of outer electrons, not the same size: going down a group adds an occupied main level."}],"explanation":"Br uses four main levels, Cl uses three. The extra level wins over the extra protons."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"أيوه. ذرة الـ sodium عرضها تقريبًا ضعف ذرة الـ chlorine. والدرس ده هيوريك ليه."},{"id":"b","feedback":"electrons أكتر تبان إنها ذرة أكبر، لكن الـ chlorine عنده كمان protons أكتر بتشد، وفي نفس المستوى الشدّ ده هو اللي بيكسب."},{"id":"c","feedback":"عدد المستويات واحد، صح، لكن الشدّ على المستويات دي مش واحد في الذرتين."}],"explanation":"الـ sodium هو الذرة الأكبر. الذرتين بيستخدموا تلات مستويات رئيسية، لكن الـ chlorine عنده 6 protons زيادة بيشدّوا electrons نفس المستوى لقرب، فالـ radius بتاعه أصغر."}},"s3":{"c":{"body":"كل ما تنزل period، بيتضاف مستوى طاقة رئيسي واحد. الـ outer electron بيبقى أبعد عن الـ nucleus، فالذرة بتبقى أكبر.","title":"لما تنزل في الـ group"}},"s5":{"o":{"items":[{"id":"li","feedback":"الـ Li عنده أقل عدد protons هنا، فشدّها على المستوى n = 2 هو الأضعف."},{"id":"b","feedback":"الأربعة بيستخدموا نفس المستوى الخارجي، والـ N عنده protons أكتر من الـ B بتشد."},{"id":"n","feedback":"الـ N عنده protons أكتر من الـ B وأقل من الـ F، والشدّ بتاعها ماشي على نفس الترتيب."},{"id":"f","feedback":"الـ F عنده أكتر عدد protons هنا، فشدّها على المستوى n = 2 هو الأقوى."}],"explanation":"نفس المستوى الخارجي (n = 2)، والـ protons بتزيد من الـ Li لحد الـ F: يعني Li > B > N > F."},"q":{"options":[{"id":"a","feedback":"صح. period زيادة يعني مستوى رئيسي زيادة، فالـ radius بيزيد."},{"id":"b","feedback":"الـ protons هي اللي بتحدد الحجم جوه المستوى الواحد، لكن الـ Br والـ Cl مش بيستخدموا نفس عدد المستويات."},{"id":"c","feedback":"protons أكتر بتشد أقوى، وده بيصغّر الذرة مش بيكبّرها."},{"id":"d","feedback":"نفس الـ group معناها نفس عدد الـ outer electrons، مش نفس الحجم: وعدد المستويات المشغولة مختلف بين الذرتين."}],"explanation":"الـ Br بيستخدم 4 مستويات رئيسية، والـ Cl بيستخدم 3. والمستوى الزيادة بيغلب الـ protons الزيادة."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":5,"is_basics":true,"lesson_no":5,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":115.8,"end_s":179.2,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-pt.atomic-radius-trend","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Atomic radius trend","duration_s":51.97,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-pt.ionization-energy","kind":"lesson","version":3,"catalog_version":1,"ord":188,"primary_concept_id":"pt.ionization-energy","concepts":[{"concept_id":"pt.ionization-energy","role":"primary"}],"title":"Ionization potential (ionization energy)","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Removing a second electron costs far more energy","correct":true},{"id":"b","text":"Sodium has only one electron to give","correct":false},{"id":"c","text":"The second electron is farther from the nucleus","correct":false}],"question":"Predict: why does sodium stop at +1?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Sodium has 11 electrons. Yet in all its compounds it is +1. You never meet $\\ce{Na^{2+}}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Why is sodium only +1?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{Na(g) -> Na+(g) + e-}","caption":"Sodium: 496 kJ/mol"},"children":[]},"t":{"type":"Text","props":{"content":"The unit is kJ/mol. The farther the electron is from the nucleus, the weaker the pull, so less energy is needed."},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Ionization potential (ionization energy)","definition":"The energy needed to remove the most loosely held electron from a gaseous atom. 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Watch what each one costs."},"children":[]},"c1":{"type":"Text","props":{"content":"1st electron: from 3s (n = 3). $\\ce{Na -> Na+}$, now [Ne]"},"visible":{"eq":1,"$state":"/k"},"children":[]},"c2":{"type":"Text","props":{"content":"2nd electron: from 2p (n = 2). $\\ce{Na+ -> Na^{2+}}$"},"visible":{"eq":2,"$state":"/k"},"children":[]},"c3":{"type":"Text","props":{"content":"3rd electron: from 2p (n = 2). $\\ce{Na^{2+} -> Na^{3+}}$"},"visible":{"eq":3,"$state":"/k"},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Successive ionization energies","definition":"The energies needed to remove the 1st, 2nd, 3rd … electrons of an atom, one after another."},"children":[]},"s1":{"type":"Stat","props":{"tone":"warning","label":"energy for electron 1","value":"496 kJ/mol"},"visible":{"eq":1,"$state":"/k"},"children":[]},"s2":{"type":"Stat","props":{"tone":"warning","label":"energy for electron 2","value":"4562 kJ/mol"},"visible":{"eq":2,"$state":"/k"},"children":[]},"s3":{"type":"Stat","props":{"tone":"warning","label":"energy for electron 3","value":"6910 kJ/mol"},"visible":{"eq":3,"$state":"/k"},"children":[]},"sl":{"type":"Slider","props":{"max":3,"min":1,"step":1,"label":"electron removed","value":{"$bindState":"/k"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","s1","c1","s2","c2","s3","c3","kt"]}}},"title":"Strip a sodium atom"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"ch":{"type":"Chart","props":{"kind":"bar","unit":"kJ/mol","series":[{"name":"Sodium","points":[{"x":"1st","y":496},{"x":"2nd","y":4562},{"x":"3rd","y":6910}]}],"caption":"Successive ionization energies of sodium","x_label":"Electron removed","y_label":"Ionization energy","annotations":[{"x":"2nd","text":"big jump"}]},"children":[]},"t1":{"type":"Text","props":{"content":"Each one is larger: the electron leaves an ion that is more and more positive."},"children":[]},"t2":{"type":"Text","props":{"content":"The 2nd costs about 9 times the 1st. It must leave the stable [Ne] arrangement, in level n = 2, nearer the nucleus."},"children":[]},"t3":{"type":"Text","props":{"content":"So sodium gives up one electron only. The big jump tells you a representative metal's oxidation state."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["ch","t1","t2","t3"]}}},"title":"The big jump"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"+3","correct":true},{"id":"b","text":"+1","correct":false},{"id":"c","text":"+4","correct":false},{"id":"d","text":"+2","correct":false}],"question":"Metal X has these successive ionization energies: 578, 1817, 2745, 11577 kJ/mol. Which oxidation state does X show in its compounds?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"The 2nd ionization energy is larger than the 1st because the 2nd electron is farther from the nucleus."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Read the data"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Ionization potential (ionization energy): the energy to remove the most loosely held electron from a gaseous atom, in kJ/mol.","Successive ionization energies increase, because each electron leaves a more positive ion.","A big jump appears when the electron must leave a stable inner level: Na stops at +1."]},"children":[]},"tbl":{"type":"DataTable","props":{"rows":[["Na","1st electron","+1"],["X (aluminum)","3rd electron","+3"]],"caption":"The big jump shows how many electrons a representative metal gives up.","headers":["Metal","Big jump after","Oxidation state"]},"children":[]},"next":{"type":"Text","props":{"muted":true,"content":"Next in Chapter 1: vanadium's energies rise gradually, with no big jump after its 4s electrons."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tbl","next","self"]},"self":{"type":"Text","props":{"content":"Can you explain why sodium forms $\\ce{Na+}$ but never $\\ce{Na^{2+}}$?"},"children":[]}}},"title":"Summary"}],"title":"Ionization potential (ionization energy)","minutes":5,"book_ref":"Background for Ch.1 The Electronic Configurations and Oxidation states, point 5, p.10 (ionization potentials of vanadium)","subtitle":"How much energy does it take to pull an electron off?","objectives":["Define ionization potential (also called ionization energy) and its unit, kJ/mol.","Explain why successive ionization energies increase, and why a big jump appears when an electron must leave a stable inner level.","Use successive ionization energies to find the oxidation state of a representative metal."],"concept_ids":["pt.ionization-energy"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good prediction. In this lesson you will see that energy."},{"id":"b","feedback":"Sodium has 11 electrons, not one: one is in the outer level (3s) and the other ten are in inner levels."},{"id":"c","feedback":"After 3s is empty, the next electron is in level n = 2, which is nearer the nucleus, not farther."}],"explanation":"Sodium's 1st electron comes from 3s, but the 2nd must leave the stable [Ne] arrangement in level n = 2, nearer the nucleus, so it costs far more energy (4562 vs 496 kJ/mol). That big jump is why sodium stops at +1."}},"s5":{"q":{"options":[{"id":"a","feedback":"Right. The big jump comes after the 3rd electron, so X gives up three. X is aluminum."},{"id":"b","feedback":"1817 is larger than 578, but every next value is larger. That steady rise is not a big jump like sodium's."},{"id":"c","feedback":"You counted all four values. The 4th costs about four times the 3rd: that is the big jump, so the 4th electron is not removed in its compounds."},{"id":"d","feedback":"From 1817 to 2745 the rise is still gradual; the big jump comes one step later, at 11577."}],"explanation":"578 → 1817 → 2745 rise steadily; 11577 is the big jump. So X shows +3."},"tf":{"explanation":"The next electron is never farther. It is removed from a positive ion, so more energy is needed.","feedback_true":"After one electron leaves, the same protons pull on fewer electrons, so the next one is held more tightly, not farther away.","feedback_false":"Right to reject it. The 2nd electron leaves a positive ion, which holds it more strongly."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"توقّع حلو. وفي الدرس ده هتشوف الطاقة دي قدامك."},{"id":"b","feedback":"الـ sodium فيه 11 electrons، مش واحد: واحد منهم في المستوى الخارجي (3s)، والعشرة التانيين في مستويات داخلية."},{"id":"c","feedback":"بعد ما الـ 3s يفضى، الـ electron اللي عليه الدور بيبقى في المستوى n = 2، وده أقرب للـ nucleus مش أبعد."}],"explanation":"أول electron في الـ sodium بيطلع من الـ 3s، لكن التاني لازم يسيب ترتيب الـ [Ne] المستقر في المستوى n = 2، اللي أقرب للـ nucleus، فبيحتاج طاقة أكبر بكتير (4562 مقابل 496 kJ/mol). الـ big jump ده هو السبب إن الـ sodium بيقف عند +1."}},"s5":{"q":{"options":[{"id":"a","feedback":"صح. القفزة الكبيرة جت بعد الـ electron التالت، يعني الـ X بيدّي تلاتة. والـ X ده هو الـ aluminum."},{"id":"b","feedback":"الـ 1817 أكبر من الـ 578، لكن كل قيمة بعدها أكبر كمان. الزيادة دي تدريجية، مش قفزة كبيرة زي بتاعة الـ sodium."},{"id":"c","feedback":"إنت عدّيت القيم الأربعة كلها. الرابعة بتكلّف حوالي أربع أضعاف التالتة: دي القفزة الكبيرة، يعني الـ electron الرابع مش بيطلع في الـ compounds بتاعته."},{"id":"d","feedback":"من 1817 لـ 2745 الزيادة لسه تدريجية؛ القفزة الكبيرة بتيجي بعدها بخطوة، عند الـ 11577."}],"explanation":"578 → 1817 → 2745 بيزيدوا بالتدريج؛ والـ 11577 هي القفزة الكبيرة. يبقى الـ X بيظهر بـ +3."},"tf":{"explanation":"الـ electron اللي بعده عمره ما بيبقى أبعد. ده بيتشال من positive ion، فبيحتاج طاقة أكتر.","feedback_true":"بعد ما electron يطلع، نفس الـ protons بتشد على electrons أقل، فالـ electron اللي بعده بيبقى ممسوك بقوة أكبر، مش أبعد.","feedback_false":"صح إنك رفضتها. الـ electron التاني بيطلع من positive ion، وده ماسكه بقوة أكبر."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":6,"is_basics":true,"lesson_no":6,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-configuration","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Electronic configurations and oxidation states","duration_s":717.229,"start_s":397.6,"end_s":467.1,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-pt.ionization-energy","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Ionization energy","duration_s":47.23,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.vanadium-ie","section_title":"Successive ionization energies of vanadium","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Successive ionization energies of vanadium"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-te.multiple-oxidation-states","kind":"lesson","version":3,"catalog_version":3,"ord":190,"primary_concept_id":"te.multiple-oxidation-states","concepts":[{"concept_id":"te.multiple-oxidation-states","role":"primary"}],"title":"Why several oxidation states","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A huge jump, like sodium's","correct":false},{"id":"b","text":"A gradual rise, with no huge jump","correct":true},{"id":"c","text":"It drops: 3d electrons are easier to remove","correct":false}],"question":"Predict: when vanadium moves on from 4s to 3d electrons, what happens to the energy needed?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Sodium's 2nd ionization potential (also called ionization energy) is about 9 times its 1st. Vanadium loses its two 4s electrons first, then its 3d electrons."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Jump or ramp?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t1":{"type":"Text","props":{"content":"Book point 5: the main transition elements have several oxidation states. Representative metals have one."},"children":[]},"t2":{"type":"Text","props":{"content":"Why the difference? The answer is in the successive ionization potentials."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Na (group IA)","+1"],["Mg (group IIA)","+2"],["Al (group IIIA)","+3"],["V (group VB)","+2, +3, +4, +5"],["Mn (group VIIB)","+2, +3, +4, +6, +7"]],"caption":"Representative metals vs transition metals (V and Mn from the book's table, p.8)","headers":["Metal","Oxidation states"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t1","tb","t2"]}}},"title":"One state or several?"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"k":0},"elements":{"t":{"type":"Text","props":{"content":"Remove vanadium's electrons one at a time. Each step shows the book's ionization potential."},"children":[]},"b0":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":3}],"caption":"V: $4s^2\\ 3d^3$"},"visible":{"eq":0,"$state":"/k"},"children":[]},"b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":3}],"caption":"$\\ce{V+}$: $4s^1\\ 3d^3$"},"visible":{"eq":1,"$state":"/k"},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":3}],"caption":"$\\ce{V^{2+}}$: $4s^0\\ 3d^3$"},"visible":{"eq":2,"$state":"/k"},"children":[]},"b3":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":2}],"caption":"$\\ce{V^{3+}}$: $4s^0\\ 3d^2$"},"visible":{"eq":3,"$state":"/k"},"children":[]},"b4":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":1}],"caption":"$\\ce{V^{4+}}$: $4s^0\\ 3d^1$"},"visible":{"eq":4,"$state":"/k"},"children":[]},"b5":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":0}],"caption":"$\\ce{V^{5+}}$: $4s^0\\ 3d^0$"},"visible":{"eq":5,"$state":"/k"},"children":[]},"e1":{"type":"Stat","props":{"tone":"warning","label":"energy for electron 1","value":"648 kJ/mol"},"visible":{"eq":1,"$state":"/k"},"children":[]},"e2":{"type":"Stat","props":{"tone":"warning","label":"energy for electron 2","value":"1346 kJ/mol"},"visible":{"eq":2,"$state":"/k"},"children":[]},"e3":{"type":"Stat","props":{"tone":"warning","label":"energy for electron 3","value":"2858 kJ/mol"},"visible":{"eq":3,"$state":"/k"},"children":[]},"e4":{"type":"Stat","props":{"tone":"warning","label":"energy for electron 4","value":"4643 kJ/mol"},"visible":{"eq":4,"$state":"/k"},"children":[]},"e5":{"type":"Stat","props":{"tone":"warning","label":"energy for electron 5","value":"6523 kJ/mol"},"visible":{"eq":5,"$state":"/k"},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"v1","from":"v0","label":"648"},{"to":"v2","from":"v1","label":"1346"},{"to":"v3","from":"v2","label":"2858"},{"to":"v4","from":"v3","label":"4643"},{"to":"v5","from":"v4","label":"6523"}],"nodes":[{"id":"v0","label":"V: 4s² 3d³"},{"id":"v1","label":"V⁺: 4s¹ 3d³"},{"id":"v2","label":"V²⁺: 4s⁰ 3d³"},{"id":"v3","label":"V³⁺: 4s⁰ 3d²"},{"id":"v4","label":"V⁴⁺: 4s⁰ 3d¹"},{"id":"v5","label":"V⁵⁺: 4s⁰ 3d⁰"}],"caption":"Successive ionization potentials of vanadium, kJ/mol (book p.10)"},"children":[]},"rv":{"type":"Reveal","props":{"label":"The book's chart for vanadium"},"children":["fd"]},"sl":{"type":"Slider","props":{"max":5,"min":0,"step":1,"label":"electrons removed","value":{"$bindState":"/k"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","b0","b1","e1","b2","e2","b3","e3","b4","e4","b5","e5","rv"]}}},"title":"Strip vanadium, read the cost"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"ch":{"type":"Chart","props":{"kind":"bar","unit":"kJ/mol","series":[{"name":"Sodium","points":[{"x":"1st","y":496},{"x":"2nd","y":4562},{"x":"3rd","y":6910}]},{"name":"Vanadium (book)","points":[{"x":"1st","y":648},{"x":"2nd","y":1346},{"x":"3rd","y":2858},{"x":"4th","y":4643},{"x":"5th","y":6523}]}],"caption":"Sodium jumps at the 2nd electron; vanadium climbs step by step","x_label":"Electron removed","y_label":"Ionization potential"},"children":[]},"t1":{"type":"Text","props":{"content":"Vanadium loses electrons from 4s and 3d in sequence. These two sublevels are close in energy."},"children":[]},"t2":{"type":"Text","props":{"content":"So its ionization potentials increase gradually. No huge jump stops it, so several oxidation states can form."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["ch","t1","t2"]}}},"title":"A gradual rise"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Y","correct":true},{"id":"b","text":"X","correct":false},{"id":"c","text":"Both: each list rises","correct":false},{"id":"d","text":"Neither: the values are too large","correct":false}],"question":"Metal X: 738, 1451, 7733 kJ/mol. Metal Y: 659, 1310, 2653, 4175 kJ/mol. Which is a transition metal with several oxidation states?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Transition metals have several oxidation states simply because they have many electrons."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Which metal is it?"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"o":{"type":"Ordering","props":{"items":[{"id":"a","text":"The atom is oxidized by losing electrons from the 4s and 3d sublevels"},{"id":"b","text":"These electrons are lost in sequence, and they are close in energy"},{"id":"c","text":"So the ionization potentials increase gradually (vanadium: 648, 1346, 2858 … kJ/mol)"},{"id":"d","text":"So several oxidation states can form"}],"prompt":"Give reasons: the main transition elements have several oxidation states. Put the answer in order."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o"]}}},"title":"Build the exam answer"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Main transition elements have several oxidation states; representative metals (Na, Mg, Al) have one.","They lose 4s and 3d electrons in sequence, and these are close in energy.","So the ionization potentials increase gradually: vanadium 648, 1346, 2858, 4643, 6523 kJ/mol."]},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Give reasons"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","chain","exam","self"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why vanadium shows no huge jump between its 4s and 3d electrons?"},"children":[]},"chain":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a"},{"to":"c","from":"b","label":"so"},{"to":"d","from":"c","label":"so"}],"nodes":[{"id":"a","label":"Electrons lost from 4s and 3d in sequence"},{"id":"b","label":"4s and 3d are close in energy"},{"id":"c","label":"Ionization potentials increase gradually"},{"id":"d","label":"Several oxidation states"}],"layout":"horizontal","caption":"Book point 5 (p.10): why main transition elements have several oxidation states"},"children":[]}}},"title":"Summary"}],"title":"Why several oxidation states","minutes":8,"book_ref":"Ch.1 The Electronic Configurations and Oxidation states, point 5 and the vanadium ionization chart, p.10","subtitle":"Vanadium's gradual climb","objectives":["State that the main transition elements have several oxidation states, while representative metals have one.","Read the book's chart of vanadium's successive ionization potentials (also called ionization energies) (648, 1346, 2858, 4643, 6523 kJ/mol).","Explain why: the 4s and 3d electrons are close in energy and are lost in sequence, so the ionization potentials increase gradually."],"concept_ids":["te.multiple-oxidation-states"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"A natural guess: 3d is in an inner level. But 4s and 3d are close in energy, unlike sodium's 3s and 2p, so there is no huge jump."},{"id":"b","feedback":"Yes: 4s and 3d are close in energy, so the book's chart shows a gradual rise with no huge jump."},{"id":"c","feedback":"Each electron leaves a more positive ion, so the next one is harder to pull off, not easier."}],"explanation":"Vanadium's 4s and 3d electrons are in sublevels close in energy, so its successive ionization potentials increase gradually, with no huge jump like sodium's."}},"s5":{"q":{"options":[{"id":"a","feedback":"Right: Y's energies rise gradually, step after step. Y is titanium (+2, +3, +4)."},{"id":"b","feedback":"X's values jump from 1451 to 7733 kJ/mol after the 2nd electron: a big jump like sodium's, so X has one oxidation state."},{"id":"c","feedback":"Every atom's successive energies rise; what matters is how. X jumps from 1451 to 7733 kJ/mol, so its rise is not gradual."},{"id":"d","feedback":"Size alone does not decide; the pattern from one step to the next does."}],"explanation":"X (magnesium): a big jump after the 2nd electron, so only +2. Y (titanium): a gradual rise, so several states."},"tf":{"explanation":"Calcium has 20 electrons, yet it has one oxidation state (+2), so the number of electrons is not the reason. Book point 5: the 4s and 3d electrons are close in energy, so the ionization potentials increase gradually.","feedback_true":"Barium (group IIA) has 56 electrons, yet it has one oxidation state. The book links several states to the 4s and 3d electrons being close in energy.","feedback_false":"Right to reject it. The reason is that the 4s and 3d electrons are close in energy, so the energies rise gradually."}},"s6":{"o":{"items":[{"id":"a","feedback":"The answer starts with what happens to the atom: it is oxidized by losing 4s and 3d electrons."},{"id":"b","feedback":"'These electrons' refers to the 4s and 3d electrons, so this line comes after they are named."},{"id":"c","feedback":"The gradual rise follows from the electrons being close in energy, so this line comes after that one."},{"id":"d","feedback":"This line is the final result, so it comes last."}],"explanation":"Lost from 4s and 3d → close in energy, in sequence → gradual rise → several oxidation states."}},"s7":{"exam":{"body":"The atom loses electrons from **4s and 3d in sequence**, which are **close in energy**. So the **ionization potentials increase gradually**, and several oxidation states form."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تخمين منطقي: الـ 3d في level جوّاني. لكن الـ 4s والـ 3d قريبين من بعض في الطاقة، مش زي الـ 3s والـ 2p بتوع الـ sodium، فمفيش قفزة كبيرة."},{"id":"b","feedback":"أيوه: الـ 4s والـ 3d قريبين من بعض في الطاقة، فالـ chart اللي في الكتاب بيوضّح زيادة بالتدريج من غير قفزة كبيرة."},{"id":"c","feedback":"كل electron بيمشي بيسيب ion positive أكتر من اللي قبله، فاللي بعده بيبقى أصعب في الشيل، مش أسهل."}],"explanation":"الـ 4s والـ 3d بتوع الـ vanadium قريبين من بعض في الطاقة، فالـ successive ionization potentials بتزيد بالتدريج، من غير قفزة كبيرة زي اللي عند الـ sodium."}},"s5":{"q":{"options":[{"id":"a","feedback":"صح: الطاقات بتاعة الـ Y بتزيد بالتدريج، خطوة ورا خطوة. الـ Y ده الـ titanium (+2، +3، +4)."},{"id":"b","feedback":"قيم الـ X بتقفز من 1451 لـ 7733 kJ/mol بعد الـ electron التاني: قفزة كبيرة زي بتاعة الـ sodium، فالـ X ليه oxidation state واحدة."},{"id":"c","feedback":"الطاقات المتتالية لأي ذرة بتزيد؛ المهم بتزيد إزاي. الـ X بيقفز من 1451 لـ 7733 kJ/mol، يعني الزيادة عنده مش بالتدريج."},{"id":"d","feedback":"الحجم لوحده مش هو اللي بيحدد؛ اللي بيحدد هو النمط من خطوة للي بعدها."}],"explanation":"الـ X (الـ magnesium): فيه قفزة كبيرة بعد الـ electron التاني، عشان كده +2 بس. الـ Y (الـ titanium): زيادة بالتدريج، فبيبقى ليه أكتر من state."},"tf":{"explanation":"الـ calcium فيه 20 electrons، ومع كده ليه oxidation state واحدة (+2)، يعني عدد الـ electrons مش هو السبب. النقطة 5 في الكتاب: الـ electrons بتوع الـ 4s والـ 3d قريبين من بعض في الطاقة، فالـ ionization potentials بتزيد بالتدريج.","feedback_true":"الـ Barium (group IIA) فيه 56 electrons، ومع كده ليه oxidation state واحدة. الكتاب بيربط وجود أكتر من state بإن الـ electrons بتوع الـ 4s والـ 3d قريبين من بعض في الطاقة.","feedback_false":"صح إنك رفضتها. السبب إن الـ electrons بتوع الـ 4s والـ 3d قريبين من بعض في الطاقة، فالطاقات بتزيد بالتدريج."}},"s6":{"o":{"items":[{"id":"a","feedback":"الإجابة بتبدأ باللي بيحصل للذرة: إنها بتتأكسد وبتفقد electrons من الـ 4s والـ 3d."},{"id":"b","feedback":"كلمة 'these electrons' راجعة على electrons الـ 4s والـ 3d، فالسطر ده ييجي بعد ما الإجابة تسمّيهم."},{"id":"c","feedback":"الزيادة بالتدريج نتيجة إن الـ electrons قريبين من بعض في الطاقة، فالسطر ده ييجي بعده."},{"id":"d","feedback":"السطر ده هو النتيجة النهائية، فييجي في الآخر."}],"explanation":"بيتشالوا من الـ 4s والـ 3d ← قريبين من بعض في الطاقة، وبيتشالوا بالترتيب ← زيادة بالتدريج ← أكتر من oxidation state."}},"s7":{"exam":{"body":"الذرة بتفقد electrons من الـ **4s والـ 3d بالترتيب**، ودول **قريبين من بعض في الطاقة**. عشان كده الـ **ionization potentials بتزيد بالتدريج**، وبيتكوّن أكتر من oxidation state."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":6,"lesson_no":12,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-configuration","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Electronic configurations and oxidation states","duration_s":717.229,"start_s":397.6,"end_s":467.1,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.multiple-oxidation-states","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Why several oxidation states","duration_s":48.65,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation 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element","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Yes","correct":true},{"id":"b","text":"No: $\\ce{Sc^{3+}}$ has no d electrons","correct":false},{"id":"c","text":"Only as an atom, not in its compounds","correct":false}],"question":"Predict: is scandium a transition element?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Scandium is the first element of the series. But $\\ce{Sc^{3+}}$, its only ion, has no d electrons at all."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Is scandium in or out?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Incomplete means 1 to 9 d electrons. Being in the d-block is not enough: a full $d^{10}$ fails. The f case is for inner transition elements."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"t","from":"q1","label":"yes"},{"to":"q2","from":"q1","label":"no"},{"to":"t","from":"q2","label":"yes"},{"to":"n","from":"q2","label":"no"}],"nodes":[{"id":"q1","label":"Atom: is the d sublevel incomplete ($d^1$ to $d^9$)?"},{"id":"t","label":"**Transition element**"},{"id":"q2","label":"Is d incomplete in one of its oxidation states?"},{"id":"n","label":"Not a transition element"}],"layout":"vertical","caption":"The definition as two tests (book p.10)"},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Transition element","definition":"The element in which the orbitals of d or f contain electrons but they are not complete, in its atomic state or in one of its oxidation states."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["kt","fd","t"]}}},"title":"The book's definition"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"d":0},"elements":{"t":{"type":"Text","props":{"content":"Slide the number of d electrons. When is the d sublevel incomplete?"},"children":[]},"b0":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":0}],"caption":"$d^0$: the d orbitals contain no electrons. Test failed."},"visible":{"eq":0,"$state":"/d"},"children":[]},"b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":1}],"caption":"$d^{1}$: incomplete. Test passed."},"visible":{"eq":1,"$state":"/d"},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":2}],"caption":"$d^{2}$: incomplete. Test passed."},"visible":{"eq":2,"$state":"/d"},"children":[]},"b3":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":3}],"caption":"$d^{3}$: incomplete. Test passed."},"visible":{"eq":3,"$state":"/d"},"children":[]},"b4":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":4}],"caption":"$d^{4}$: incomplete. Test passed."},"visible":{"eq":4,"$state":"/d"},"children":[]},"b5":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":5}],"caption":"$d^{5}$: incomplete. Test passed."},"visible":{"eq":5,"$state":"/d"},"children":[]},"b6":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":6}],"caption":"$d^{6}$: incomplete. Test passed."},"visible":{"eq":6,"$state":"/d"},"children":[]},"b7":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":7}],"caption":"$d^{7}$: incomplete. Test passed."},"visible":{"eq":7,"$state":"/d"},"children":[]},"b8":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":8}],"caption":"$d^{8}$: incomplete. Test passed."},"visible":{"eq":8,"$state":"/d"},"children":[]},"b9":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":9}],"caption":"$d^{9}$: incomplete. Test passed."},"visible":{"eq":9,"$state":"/d"},"children":[]},"sl":{"type":"Slider","props":{"max":10,"min":0,"step":1,"label":"d electrons","value":{"$bindState":"/d"}},"children":[]},"b10":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"d","electrons":10}],"caption":"$d^{10}$: complete. Test failed; check another state."},"visible":{"eq":10,"$state":"/d"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","b0","b1","b2","b3","b4","b5","b6","b7","b8","b9","b10"]}}},"title":"Complete or not?"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"$\\ce{_{25}Mn}$: [Ar] $4s^2$ 3d___ . In $\\ce{KMnO4}$ (+7), the Mn has 3d___ .","answers":[["5","five"],["0","zero"]],"mistakes":[{"id":"m1","blank":0,"answer":"7"},{"id":"m2","blank":0,"answer":"3"},{"id":"m3","blank":1,"answer":"5"},{"id":"m4","blank":1,"answer":"2"}]},"children":[]},"h":{"type":"Heading","props":{"text":"Your turn: manganese","level":3},"children":[]},"hl":{"type":"HintLadder","props":{},"children":[]},"r1":{"type":"Reveal","props":{"label":"Step 1: Test the atom"},"children":["r1f","r1t"]},"r2":{"type":"Reveal","props":{"label":"Step 2: Does Sc³⁺ change the verdict?"},"children":["r2t"]},"r1f":{"type":"Formula","props":{"latex":"\\ce{_{21}Sc}:\\ [\\text{Ar}]\\ 4s^2\\ 3d^1"},"children":[]},"r1t":{"type":"Text","props":{"content":"3d holds one electron: incomplete. Scandium passes on the atom alone."},"children":[]},"r2t":{"type":"Text","props":{"content":"No. $\\ce{Sc^{3+}}$ is [Ar], with $3d^0$. But the definition says atom OR one of its oxidation states. One pass is enough."},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["r1","r2","h","f","hl"]}}},"title":"Worked: scandium; your turn: manganese"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"ti","text":"$\\ce{_{22}Ti}$: [Ar] $4s^2\\ 3d^2$"},{"id":"ca","text":"$\\ce{_{20}Ca}$: [Ar] $4s^2$; only state +2: [Ar]"},{"id":"ga","text":"$\\ce{_{31}Ga}$: [Ar] $4s^2\\ 3d^{10}\\ 4p^1$; state +3: [Ar] $3d^{10}$"},{"id":"co","text":"$\\ce{_{27}Co}$: [Ar] $4s^2\\ 3d^7$"},{"id":"k","text":"$\\ce{_{19}K}$: [Ar] $4s^1$; only state +1: [Ar]"},{"id":"zn","text":"$\\ce{_{30}Zn}$: [Ar] $4s^2\\ 3d^{10}$; only state +2: [Ar] $3d^{10}$"}],"answer":{"no":["ca","ga","k","zn"],"yes":["ti","co"]},"prompt":"Sort each element with the book's definition.","categories":[{"id":"yes","label":"Transition element"},{"id":"no","label":"Not a transition element"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c"]}}},"title":"Sort the elements"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The definition is met by the atom or one of its states, and the Ti atom is $3d^2$","correct":true},{"id":"b","text":"Nothing: an element with a $3d^0$ state is not transition","correct":false},{"id":"c","text":"Ti in +4 still keeps its 4s electrons","correct":false}],"question":"In $\\ce{TiO2}$, titanium is +4, so its d sublevel is empty ($3d^0$). A student says titanium is therefore not a transition element. What is wrong?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"To decide if an element is a transition element, we check only its neutral atom."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Titanium in TiO₂"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["A transition element has d (or f) orbitals that contain electrons but are not complete.","Test the atom first; if it fails, test its oxidation states. One pass is enough.","Scandium is a transition element: its atom is $3d^1$, though $\\ce{Sc^{3+}}$ is $3d^0$."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_t"]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"next":{"type":"Text","props":{"muted":true,"content":"Next: copper's atom is $3d^{10}$ like zinc's, yet copper is a transition element. Why?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","next","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why scandium counts, though $\\ce{Sc^{3+}}$ has no d electrons?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"Scandium's atom is $3d^1$: its d orbitals contain electrons but are not complete, so the atom passes the test. One pass is enough, though $\\ce{Sc^{3+}}$ is $3d^0$."},"children":[]}}},"title":"Summary"}],"title":"Definition of the transition element","minutes":7,"book_ref":"Ch.1 point 6 'The transition element', p.10","subtitle":"Two places to look for an incomplete d sublevel","objectives":["State the book's definition of the transition element.","Apply both tests: first the atom, then its oxidation states.","Show that scandium is a transition element (atom $3d^1$), though $\\ce{Sc^{3+}}$ has no d electrons."],"concept_ids":["te.definition"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good prediction. The book's definition also checks the atom. This lesson shows how."},{"id":"b","feedback":"Many websites say this, but the book's definition does not look only at the ion: it also checks the Sc atom."},{"id":"c","feedback":"An element is either a transition element or not; it does not switch between the atom and its compounds."}],"explanation":"Scandium is a transition element. The book's definition also checks the atom: the Sc atom is $3d^1$, an incomplete d sublevel, even though $\\ce{Sc^{3+}}$ has no d electrons."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"7 is the total in 4s and 3d, and 2 of those are in 4s."},{"id":"m2","feedback":"Mn has 25 electrons: [Ar] (18) and 4s (2) take 20 of them, and the rest are in 3d."},{"id":"m3","feedback":"That is the atom. In +7, Mn has lost 7 electrons: the 2 in 4s first, then the rest from 3d."},{"id":"m4","feedback":"Losing 7 electrons empties 4s first, and the other electrons lost come out of 3d."}],"explanation":"Mn atom: $3d^5$, incomplete, so Mn is a transition element. Mn(+7) is $3d^0$, but one pass is enough."},"hl":{"hints":["[Ar] holds 18 electrons; 4s holds 2.","For +7, start from 7 electrons in 4s and 3d.","4s leaves first, then 3d."]}},"s5":{"c":{"items":[{"id":"ti","feedback":"The Ti atom has 2 d electrons, between 1 and 9, so its d sublevel is incomplete."},{"id":"ca","feedback":"Ca has no d electrons, in the atom or in its ion, so it has no incomplete d sublevel."},{"id":"ga","feedback":"Ga is $3d^{10}$ in the atom and in the +3 state: the d sublevel is complete in both."},{"id":"co","feedback":"The Co atom has 7 d electrons in 5 orbitals, so its d sublevel is incomplete."},{"id":"k","feedback":"K has no d electrons, in the atom or in its ion."},{"id":"zn","feedback":"Zinc sits in the d-block, but position is not the test: its d sublevel is complete ($3d^{10}$) in the atom and in the ion."}],"explanation":"Ti ($3d^2$) and Co ($3d^7$) pass on the atom. Ca and K have no d electrons. Ga and Zn are $d^{10}$ in the atom and in their ions. Being in or near the d-block is not enough."}},"s6":{"q":{"options":[{"id":"a","feedback":"Right. One incomplete d is enough, and the titanium atom has it."},{"id":"b","feedback":"Then scandium would fail too: the definition does not say 'in all of its states'."},{"id":"c","feedback":"Ions lose their 4s electrons first, so at +4 titanium has no 4s electrons left."}],"explanation":"The definition is met when the d sublevel is incomplete in the atom or in any one of its oxidation states. The Ti atom is $3d^2$, so titanium is a transition element even though Ti(+4) is $3d^0$."},"tf":{"explanation":"'… in their atomic state or in one of their oxidation states' (book p.10).","feedback_true":"The definition's last words also look for an incomplete d in one of the element's oxidation states, not just in its neutral atom.","feedback_false":"Right. It checks the atom and its oxidation states. The next lesson shows why that matters."}},"s7":{"exam":{"body":"It is the element in which the orbitals of **d or f contain electrons** but they are **not complete** in its **atomic state** or in **one of its oxidation states**.","title":"Define: the transition element"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"توقّع حلو. تعريف الكتاب بيبص على الذرة كمان، والدرس ده هيوريك إزاي."},{"id":"b","feedback":"مواقع كتير بتقول كده، لكن تعريف الكتاب مش بيبص على الـ ion لوحده: بيبص على ذرة الـ Sc كمان."},{"id":"c","feedback":"العنصر يا إما transition element يا إما لأ، مش بيتحوّل من ده لده. التعريف بيبص على الذرة وعلى الـ oxidation states بتاعتها مع بعض."}],"explanation":"الـ scandium يعتبر transition element. تعريف الكتاب بيبص على الذرة كمان: ذرة الـ Sc فيها $3d^1$، يعني d sublevel مش مكتمل، حتى لو الـ $\\ce{Sc^{3+}}$ مفيهوش d electrons."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"الـ 7 دول مجموع اللي في الـ 4s والـ 3d، والـ 4s واخد منهم 2."},{"id":"m2","feedback":"الـ Mn عنده 25 electrons: الـ [Ar] واخد 18 والـ 4s واخد 2، والباقي كله في الـ 3d."},{"id":"m3","feedback":"ده في الذرة. في الـ +7 الـ Mn خسر 7 electrons: من الـ 4s الأول، وبعدين الباقي من الـ 3d."},{"id":"m4","feedback":"لما يخسر 7 electrons، الـ 4s بيفضى الأول (2)، والباقي كله بيمشي من الـ 3d."}],"explanation":"ذرة الـ Mn: $3d^5$، يعني مش مكتملة، فالـ Mn يبقى transition element. صحيح الـ Mn(+7) بيبقى $3d^0$، لكن يكفي إنه ينجح في اختبار واحد."},"hl":{"hints":["الـ [Ar] فيه 18 electrons، والـ 4s فيه 2.","عشان الـ +7، ابدأ من الـ 7 electrons اللي في الـ 4s والـ 3d.","الـ electrons بتخرج من الـ 4s الأول، وبعدين من الـ 3d."]}},"s5":{"c":{"items":[{"id":"ti","feedback":"ذرة الـ Ti فيها 2 d electrons، والرقم ده بين 1 و9، يعني الـ d sublevel مش مكتمل."},{"id":"ca","feedback":"الـ Ca مفيهوش d electrons، لا في الذرة ولا في الـ ion بتاعه."},{"id":"ga","feedback":"الـ Ga بيبقى $3d^{10}$ في الذرة وفي الـ +3 state، يعني فيه 10 d electrons والـ d مكتمل في الاتنين."},{"id":"co","feedback":"ذرة الـ Co فيها 7 d electrons، والـ 5 orbitals مابيكتملوش غير بـ 10."},{"id":"k","feedback":"الـ K مفيهوش d electrons، لا في الذرة ولا في الـ ion بتاعه."},{"id":"zn","feedback":"الـ zinc موجود في الـ d-block، لكن المكان مش هو الاختبار: الـ d electrons بتوعه 10 ($3d^{10}$) ومكتملين في الذرة وفي الـ ion."}],"explanation":"الـ Ti ($3d^2$) والـ Co ($3d^7$) بينجحوا من الذرة على طول. الـ Ca والـ K مفيش عندهم d electrons أصلًا. والـ Ga والـ Zn بيبقوا $d^{10}$ في الذرة وفي الـ ions بتوعهم. إن العنصر يكون في الـ d-block أو جنبه مش كفاية."}},"s6":{"q":{"options":[{"id":"a","feedback":"صح. يكفي d واحد مش مكتمل، وذرة الـ titanium عندها كده."},{"id":"b","feedback":"لو كده، الـ scandium كمان هيسقط. والتعريف مش بيشترط إن الـ d يبقى مش مكتمل «في كل حالاته»."},{"id":"c","feedback":"الـ ions بتخسر الـ 4s electrons الأول، فالـ Ti عند الـ +4 مابيفضلش معاه أي 4s electrons."}],"explanation":"التعريف بيتحقق لو الـ d sublevel مش مكتمل في الذرة أو في أي oxidation state من بتوعها. وذرة الـ Ti فيها $3d^2$، فالـ titanium يعتبر transition element حتى لو الـ Ti(+4) بقى $3d^0$."},"tf":{"explanation":"آخر التعريف بيقول: '… in their atomic state or in one of their oxidation states' (الكتاب ص 10).","feedback_true":"آخر كلام في التعريف بيقول إنه بيدوّر على d مش مكتمل في الذرة أو في واحدة من الـ oxidation states بتاعتها، مش في الذرة لوحدها.","feedback_false":"صح. التعريف بيبص على الذرة وعلى الـ oxidation states بتاعتها. والدرس الجاي هيوريك ليه ده مهم."}},"s7":{"exam":{"body":"هو العنصر اللي الـ orbitals بتاعة الـ **d أو f فيها electrons** لكنها **مش مكتملة**، سواء في **الذرة نفسها** أو في **واحدة من الـ oxidation states** بتاعته.","title":"عرّف: الـ transition 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Elements","The Electronic Configurations and Oxidation states","The transition element (definition)"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.definition-applied","kind":"lesson","version":4,"catalog_version":3,"ord":194,"primary_concept_id":"te.definition-applied","concepts":[{"concept_id":"te.definition-applied","role":"primary"}],"title":"Are coinage metals and zinc transition elements?","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Both: they are in the d-block","correct":false},{"id":"b","text":"Neither: their atoms are $d^{10}$","correct":false},{"id":"c","text":"Copper only","correct":true},{"id":"d","text":"Zinc only","correct":false}],"question":"Predict: which of them are transition elements?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Copper ($[\\text{Ar}]\\ 4s^1\\ 3d^{10}$) and zinc ($[\\text{Ar}]\\ 4s^2\\ 3d^{10}$) both have a complete 3d in the atom."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Two complete 3d sublevels"},{"id":"s2","kind":"interact","spec":{"root":"root","state":{"k":0},"elements":{"c":{"type":"Callout","props":{"variant":"tip"},"visible":{"eq":2,"$state":"/k"},"children":[]},"t":{"type":"Text","props":{"content":"Copper's oxidation states are +1 and +2. Remove electrons and watch 3d."},"children":[]},"b0":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":10}],"caption":"Cu atom: $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$: d complete"},"visible":{"eq":0,"$state":"/k"},"children":[]},"b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":10}],"caption":"$\\ce{Cu+}$: $[\\text{Ar}]\\ 3d^{10}$: d still complete"},"visible":{"eq":1,"$state":"/k"},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":9}],"caption":"$\\ce{Cu^{2+}}$: $[\\text{Ar}]\\ 3d^9$: d incomplete"},"visible":{"eq":2,"$state":"/k"},"children":[]},"sl":{"type":"Slider","props":{"max":2,"min":0,"step":1,"label":"electrons lost","value":{"$bindState":"/k"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","b0","b1","b2","c"]}}},"title":"Strip copper"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"kt":{"type":"KeyTerm","props":{"term_en":"Coinage metals","definition":"Copper, silver and gold, in group IB."},"children":[]},"t1":{"type":"Text","props":{"content":"In the atom, the d sublevel is completely filled ($d^{10}$) in all three."},"children":[]},"t2":{"type":"Text","props":{"content":"But in the oxidation state +2 or +3, d is partially filled ($d^9$ or $d^8$). So they are transition elements."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["$\\ce{_{29}Cu}$","$4s^1\\ 3d^{10}$"],["$\\ce{_{47}Ag}$","$5s^1\\ 4d^{10}$"],["$\\ce{_{79}Au}$","$6s^1\\ 5d^{10}$"]],"caption":"Book Exercise 1, p.10","headers":["Metal","Atom"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["kt","tb","t1","t2"]}}},"title":"Coinage metals"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"k":0},"elements":{"c":{"type":"Callout","props":{"variant":"info"},"visible":{"eq":2,"$state":"/k"},"children":[]},"t":{"type":"Text","props":{"content":"Zinc's only oxidation state is +2. Remove its electrons and watch 3d."},"children":[]},"b0":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":2},{"boxes":5,"label":"3d","electrons":10}],"caption":"Zn atom: $[\\text{Ar}]\\ 4s^2\\ 3d^{10}$"},"visible":{"eq":0,"$state":"/k"},"children":[]},"b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":1},{"boxes":5,"label":"3d","electrons":10}],"caption":"one 4s electron gone"},"visible":{"eq":1,"$state":"/k"},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"4s","electrons":0},{"boxes":5,"label":"3d","electrons":10}],"caption":"$\\ce{Zn^{2+}}$: $[\\text{Ar}]\\ 3d^{10}$"},"visible":{"eq":2,"$state":"/k"},"children":[]},"sl":{"type":"Slider","props":{"max":2,"min":0,"step":1,"label":"electrons lost","value":{"$bindState":"/k"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","b0","b1","b2","c"]}}},"title":"Strip zinc"},{"id":"s5","kind":"example","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"$\\ce{_{47}Ag}$: [Kr] $5s^1\\ 4d^{10}$. $\\ce{Ag^{2+}}$: [Kr] 4d___ . So silver ___ a transition element (type: is / is not).","answers":[["9","nine"],["is"]],"mistakes":[{"id":"m1","blank":0,"answer":"10"},{"id":"m2","blank":0,"answer":"8"},{"id":"m3","blank":1,"answer":"is not"}]},"children":[]},"h":{"type":"Heading","props":{"text":"Your turn: silver in the +2 state","level":3},"children":[]},"hl":{"type":"HintLadder","props":{},"children":[]},"kr":{"type":"Text","props":{"muted":true,"content":"[Kr] stands for krypton's 36 electrons, as [Ar] stands for argon's 18."},"children":[]},"r1":{"type":"Reveal","props":{"label":"Step 1: The gold atom"},"children":["r1b"]},"r2":{"type":"Reveal","props":{"label":"Step 2: Gold in the +3 state"},"children":["r2b","r2t"]},"r1b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"6s","electrons":1},{"boxes":5,"label":"5d","electrons":10}],"caption":"$\\ce{_{79}Au}$: … $6s^1\\ 5d^{10}$: d complete"},"children":[]},"r2b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":1,"label":"6s","electrons":0},{"boxes":5,"label":"5d","electrons":8}],"caption":"$\\ce{Au^{3+}}$: … $5d^8$: d incomplete"},"children":[]},"r2t":{"type":"Text","props":{"content":"Gold loses its 6s electron, then two 5d electrons. $5d^8$ is incomplete, so gold is a transition element."},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["r1","r2","h","kr","f","hl"]}}},"title":"Worked: gold; your turn: silver"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Yes: d is incomplete in its +2 state","correct":true},{"id":"b","text":"No: its atom is $d^{10}$","correct":false},{"id":"c","text":"No: it has no s electrons in the atom","correct":false}],"question":"Element X: atom [Kr] $4d^{10}$. In its +2 state: [Kr] $4d^8$. Is X a transition element?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Groups IB and IIB are both outside the transition elements."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"New cases"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Coinage metals (Cu, Ag, Au): $d^{10}$ in the atom, but $d^9$ or $d^8$ in the +2 or +3 state. They are transition elements.","Zn, Cd, Hg: $d^{10}$ in the atom and in the +2 ion. They are not transition elements, though they sit in the d-block.","Test the atom first, then its oxidation states."]},"children":[]},"tbl":{"type":"DataTable","props":{"rows":[["$\\ce{_{29}Cu}$","$[\\text{Ar}]\\ 4s^1\\ 3d^{10}$","$\\ce{Cu^{2+}}$: $[\\text{Ar}]\\ 3d^9$","incomplete","yes"],["$\\ce{_{30}Zn}$","$[\\text{Ar}]\\ 4s^2\\ 3d^{10}$","$\\ce{Zn^{2+}}$: $[\\text{Ar}]\\ 3d^{10}$","complete","no"]],"caption":"Test the atom, then the ion","headers":["Element","Atom","Ion","d in the ion","Transition element?"],"highlight":[{"col":3,"row":0},{"col":3,"row":1}]},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tbl","exam","self"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why copper is a transition element but zinc is not?"},"children":[]}}},"title":"Summary"}],"title":"Are coinage metals and zinc transition elements?","minutes":7,"book_ref":"Ch.1 Exercise 1 (coinage metals), p.10; Exercise 2 (Zn, Cd, Hg), p.11; Evaluation Q7.3, p.27","subtitle":"Copper is in, zinc is out","objectives":["Show that the coinage metals (Cu, Ag, Au) are transition elements: $d^{10}$ in the atom, but $d^9$ or $d^8$ in the +2 or +3 state.","Show that Zn, Cd and Hg are not: $d^{10}$ in the atom and in the +2 ion.","Decide for a new element from its atom and ion configurations, and justify it."],"concept_ids":["te.definition-applied"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Being in the d-block is not the book's test: the definition checks the d sublevel in the atom and in the oxidation states."},{"id":"b","feedback":"The atom is just the first test: the definition also checks the oxidation states, where the d sublevel can become incomplete."},{"id":"c","feedback":"Good prediction. Copper's ions hold the key."},{"id":"d","feedback":"Zinc's only ion is +2: it loses its two 4s electrons, so its 3d stays complete ($3d^{10}$)."}],"explanation":"Both atoms have a complete 3d. In $\\ce{Cu^{2+}}$ the 3d becomes incomplete ($3d^9$), so copper is a transition element; in $\\ce{Zn^{2+}}$ the 3d stays complete ($3d^{10}$), so zinc is not."}},"s2":{"c":{"body":"In $\\ce{Cu^{2+}}$ the 3d sublevel is incomplete ($3d^9$). So copper passes the second test.","title":"Test 2 passed"}},"s4":{"c":{"body":"$\\ce{Zn^{2+}}$ is still $3d^{10}$. Zinc, cadmium ($5s^2\\ 4d^{10}$) and mercury ($6s^2\\ 5d^{10}$) are $d^{10}$ in the atom and in the +2 ion. So they are not transition elements.","title":"Book Exercise 2, p.11"}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"$4d^{10}$ is the atom's d: a 2+ ion has lost two electrons, the 5s one and one more from 4d."},{"id":"m2","feedback":"$4d^8$ would mean three electrons lost in total (the 5s one plus two from 4d), but a 2+ ion has lost two."},{"id":"m3","feedback":"In $\\ce{Ag^{2+}}$ the d sublevel is incomplete, so silver meets the definition."}],"explanation":"$\\ce{Ag^{2+}}$: [Kr] $4d^9$: incomplete. So silver is a transition element."},"hl":{"hints":["The outer s electron leaves first.","A 2+ ion has lost two electrons in total.","Is $4d^{10}$ minus one complete?"]}},"s6":{"q":{"options":[{"id":"a","feedback":"Right. One incomplete d, in the atom or in a state, is enough."},{"id":"b","feedback":"Checking the atom alone is not enough: the definition also counts an incomplete d in one of the oxidation states."},{"id":"c","feedback":"The definition is about the d (or f) sublevel, not s, so having no s electrons does not decide it."}],"explanation":"The atom of X is $4d^{10}$, but in the +2 state it is $4d^8$, an incomplete d sublevel, so X is a transition element (X is palladium)."},"tf":{"explanation":"Cu, Ag, Au have $d^9$ or $d^8$ in the +2 or +3 state. Zn, Cd, Hg stay $d^{10}$.","feedback_true":"The two groups differ in their ions: Cu, Ag and Au have an incomplete d in the +2 or +3 state, while Zn, Cd and Hg keep $d^{10}$.","feedback_false":"Right. Group IB (Cu, Ag, Au) is in; group IIB (Zn, Cd, Hg) is out."}},"s7":{"exam":{"body":"In the atom, the d sublevel is completely filled ($d^{10}$). In the oxidation state **(+2) or (+3)** it is partially filled ($d^9$) or ($d^8$).","title":"Give reasons: coinage metals are transition elements"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"وجود العنصر في الـ d-block مش هو اختبار الكتاب: التعريف بيبص على الـ d sublevel في الذرة وفي الـ oxidation states."},{"id":"b","feedback":"الذرة مجرد أول اختبار: التعريف بيبص كمان على الـ oxidation states، واللي ممكن الـ d sublevel يبقى فيها incomplete."},{"id":"c","feedback":"توقّع حلو. السر في الـ ions بتاعة الـ copper."},{"id":"d","feedback":"الـ zinc ملوش غير ion واحد: +2، بيخسر فيه الـ 2 electrons بتوع الـ 4s، فالـ 3d بتاعه بيفضل مكتمل ($3d^{10}$)."}],"explanation":"الذرتين الـ 3d بتاعهم مكتمل. في الـ $\\ce{Cu^{2+}}$ الـ 3d بيبقى incomplete ($3d^9$)، فالـ copper يبقى transition element؛ لكن في الـ $\\ce{Zn^{2+}}$ الـ 3d بيفضل مكتمل ($3d^{10}$)، فالـ zinc لأ."}},"s2":{"c":{"body":"في الـ $\\ce{Cu^{2+}}$ الـ 3d sublevel بيبقى incomplete ($3d^9$)، فالـ copper بينجح في الاختبار التاني.","title":"نجح في الاختبار التاني"}},"s4":{"c":{"body":"الـ $\\ce{Zn^{2+}}$ لسه $3d^{10}$. الـ zinc والـ cadmium ($5s^2\\ 4d^{10}$) والـ mercury ($6s^2\\ 5d^{10}$) كلهم $d^{10}$ في الذرة وفي الـ +2 ion، وعشان كده مش transition elements.","title":"تمرين الكتاب 2، صفحة 11"}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"الـ $4d^{10}$ ده الـ d بتاع الذرة: الـ 2+ ion خسر 2 electrons، واحد من الـ 5s وواحد كمان من الـ 4d."},{"id":"m2","feedback":"الـ $4d^8$ معناه إنه خسر 3 electrons في المجموع (واحد من الـ 5s واتنين من الـ 4d)، لكن الـ 2+ ion خسر اتنين."},{"id":"m3","feedback":"في الـ $\\ce{Ag^{2+}}$ الـ d sublevel مش مكتمل، فالـ silver بينطبق عليه التعريف."}],"explanation":"$\\ce{Ag^{2+}}$: [Kr] $4d^9$: يعني incomplete. عشان كده الـ silver يبقى transition element."},"hl":{"hints":["الـ s electron اللي برّه هو اللي بيمشي الأول.","الـ 2+ ion خسر 2 electrons في المجموع.","الـ $4d^{10}$ لو نقص منه واحد، يفضل مكتمل؟"]}},"s6":{"q":{"options":[{"id":"a","feedback":"صح. يكفي d واحد incomplete، في الذرة أو في state من الـ states."},{"id":"b","feedback":"إنك تبص على الذرة لوحدها مش كفاية: التعريف بيحسب كمان الـ d لو incomplete في state من الـ oxidation states."},{"id":"c","feedback":"التعريف بيتكلم عن الـ d (أو الـ f) sublevel، مش الـ s، فإن مفيش s electrons ده مش هو اللي بيحدد."}],"explanation":"ذرة الـ X هي $4d^{10}$، لكن في الـ +2 state بتبقى $4d^8$، يعني d sublevel مش مكتمل، فالـ X يبقى transition element (الـ X ده هو الـ palladium)."},"tf":{"explanation":"الـ Cu والـ Ag والـ Au بيبقى عندهم $d^9$ أو $d^8$ في الـ +2 أو +3 state. أما الـ Zn والـ Cd والـ Hg فبيفضلوا $d^{10}$.","feedback_true":"الـ groups الاتنين بيختلفوا في الـ ions: الـ Cu والـ Ag والـ Au الـ d بتاعهم بيبقى incomplete في الـ +2 أو +3 state، أما الـ Zn والـ Cd والـ Hg فبيفضلوا $d^{10}$.","feedback_false":"صح. الـ group IB (Cu, Ag, Au) جوه، والـ group IIB (Zn, Cd, Hg) برّه."}},"s7":{"exam":{"body":"في الذرة، الـ d sublevel بيبقى مليان خالص ($d^{10}$). لكن في الـ oxidation state **(+2) أو (+3)** بيبقى مليان جزئيًا ($d^9$) أو ($d^8$).","title":"علّل: الـ coinage metals تعتبر transition elements"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":8,"lesson_no":14,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-configuration","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Electronic configurations and oxidation states","duration_s":717.229,"start_s":557,"end_s":628.7,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.definition-applied","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Are coinage metals and zinc transition elements?","duration_s":41.44,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.ex1","section_title":"Coinage metals","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Coinage metals"],"exercise":"Exercise 1","relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":11,"page_to":11,"section_key":"ch1.config.ex2","section_title":"Zinc, cadmium and mercury","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Zinc, cadmium and mercury"],"exercise":"Exercise 2","relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"3","relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.atomic-mass-trend","kind":"lesson","version":2,"catalog_version":3,"ord":245,"primary_concept_id":"te.atomic-mass-trend","concepts":[{"concept_id":"te.atomic-mass-trend","role":"primary"}],"title":"Atomic mass: why nickel is abnormal","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It is a misprint in the table","correct":false},{"id":"b","text":"Its atomic mass is an average over its isotopes","correct":true},{"id":"c","text":"Nickel has fewer protons than cobalt","correct":false}],"question":"Predict: why is nickel lighter than cobalt?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Nickel (Z = 28) comes after cobalt (Z = 27). Yet the book's table gives nickel the smaller atomic mass."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Lighter but later?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Book point 1: the atomic mass **increases gradually with increasing atomic number**."},"children":[]},"ch":{"type":"Chart","props":{"kind":"line","unit":"u","series":[{"name":"Atomic mass","points":[{"x":"Sc","y":45},{"x":"Ti","y":47.9},{"x":"V","y":51},{"x":"Cr","y":52},{"x":"Mn","y":54.9},{"x":"Fe","y":55.9},{"x":"Co","y":58.9},{"x":"Ni","y":58.7},{"x":"Cu","y":63.5}]}],"caption":"Atomic mass from Sc to Cu (book's table, p.12, for illustration only)","x_label":"Element (Sc → Cu)","y_label":"Atomic mass","highlight":["Co","Ni"],"annotations":[{"x":"Ni","text":"abnormal"}]},"children":[]},"t2":{"type":"Text","props":{"content":"One element breaks the pattern: nickel, 58.7 u, after cobalt, 58.9 u."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["ch","t","t2"]}}},"title":"The atomic mass column"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"The book's reason: nickel has **five stable isotopes**. Its atomic mass, 58.7 u, is their average."},"children":[]},"t2":{"type":"Text","props":{"content":"Most nickel atoms are the light isotope nickel-58. So the average stays below cobalt's 58.9 u."},"children":[]},"tbl":{"type":"DataTable","props":{"rows":[["Cobalt","27","one (all cobalt-59)","58.9 u"],["Nickel","28","five (mostly nickel-58)","58.7 u"]],"caption":"One isotope against a mix of five","headers":["Element","Z","Stable isotopes","Atomic mass"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","t2","tbl","m"]}}},"title":"Five isotopes, one average"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"p":50},"elements":{"t":{"type":"Text","props":{"content":"A simplified model: keep only nickel's two most common isotopes, nickel-58 and nickel-60. Change the share of nickel-58."},"children":[]},"co":{"type":"Stat","props":{"tone":"neutral","label":"Cobalt (all cobalt-59)","value":"58.9 u"},"children":[]},"ok":{"type":"Callout","props":{"variant":"tip"},"visible":{"eq":65,"$state":"/p"},"children":[]},"sl":{"type":"Slider","props":{"max":100,"min":0,"step":5,"unit":"%","label":"share of nickel-58","value":{"$bindState":"/p"}},"children":[]},"st":{"type":"Stat","props":{"tone":"brand","unit":"u","label":"Average atomic mass of the mix","value":{"args":{"p":{"$state":"/p"},"expr":"58*p/100 + 60*(100-p)/100","digits":1},"$computed":"calc"}},"children":[]},"row":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["st","co"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","row","ok"]}}},"title":"Mix nickel's isotopes"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Atomic mass depends on the mix of isotopes, not only on the number of protons","correct":true},{"id":"b","text":"It must be a misprint: the larger Z is always heavier","correct":false},{"id":"c","text":"Potassium has fewer protons than argon","correct":false}],"question":"Outside the transition series: argon (Z = 18) has atomic mass 39.9, potassium (Z = 19) only 39.1. Which statement explains it?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Atomic mass always increases with atomic number."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"A new pair"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"The atomic mass ___ gradually with increasing atomic number. But nickel is abnormal: it has five stable ___ with average mass 58.7 u.","answers":[["increases","rises","increase"],["isotopes","isotope"]],"mistakes":[{"id":"m1","blank":0,"answer":"decreases"},{"id":"m2","blank":0,"answer":"decrease"},{"id":"m3","blank":1,"answer":"electrons"},{"id":"m4","blank":1,"answer":"neutrons"},{"id":"m5","blank":1,"answer":"protons"}]},"children":[]},"h":{"type":"HintLadder","props":{},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","h"]}}},"title":"Write the book's sentence"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Atomic mass increases gradually with increasing atomic number from Sc to Cu.","Nickel is abnormal: 58.7 u, less than cobalt's 58.9 u.","Reason: nickel has five stable isotopes; 58.7 u is their average, and light nickel-58 is the most common."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["anst"]},"anst":{"type":"Text","props":{"content":"Nickel has five stable isotopes, and its atomic mass, 58.7 u, is their average. Most nickel atoms are the light isotope nickel-58, so the average stays below cobalt's 58.9 u, even with one more proton."},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","ans"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why nickel is lighter than cobalt, though it has one more proton?"},"children":[]}}},"title":"Summary"}],"title":"Atomic mass: why nickel is abnormal","minutes":7,"book_ref":"Ch.1 The general properties of the first transition elements, data table and point 1, p.12","subtitle":"One element breaks the pattern","objectives":["Read the atomic mass column of the book's table (for illustration only).","State that atomic mass increases gradually with increasing atomic number.","Explain why nickel (58.7 u) is abnormal: it has five stable isotopes with average mass 58.7 u."],"concept_ids":["te.atomic-mass-trend"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"A fair suspicion, but every data book shows the same value: atomic mass depends on the neutrons too, not on the protons alone."},{"id":"b","feedback":"Good thinking. You met average atomic mass with isotopes. This lesson applies it to nickel."},{"id":"c","feedback":"Z counts protons: nickel has 28, cobalt 27, so nickel has more. The lower mass comes from its mix of isotopes, which differ in their number of neutrons."}],"explanation":"Atomic mass is the average mass of an element's isotopes. Nickel has five stable isotopes with average mass 58.7 u, lower than cobalt's, even though nickel has one more proton."}},"s3":{"m":{"statement":"Nickel's 58.7 is a misprint.","correction":"It is a real average, weighted by how common each isotope is. Natural cobalt is all cobalt-59, so its value is 58.9."}},"s4":{"ok":{"body":"58.7: the book's value. Mostly light nickel-58 keeps the average below cobalt's 58.9."}},"s5":{"q":{"options":[{"id":"a","feedback":"Right. Most argon atoms are the heavy isotope argon-40, so argon's average is higher, as with cobalt and nickel."},{"id":"b","feedback":"That is the same trap as nickel's: atomic mass is an average over isotopes, not a count of protons."},{"id":"c","feedback":"Z gives the protons: 19 for potassium, 18 for argon, so potassium has more. The difference in mass comes from the isotope mix."}],"explanation":"Atomic mass is an average over an element's isotopes, so it depends on the isotope mix, not on the number of protons alone. Most argon atoms are argon-40, which lifts argon's average above potassium's."},"tf":{"explanation":"Atomic number counts protons. Atomic mass is the average over the isotopes, so the two need not rise together.","feedback_true":"Cobalt and nickel break this: atomic mass is an average over the isotopes, so it depends on the neutrons too, not on the protons alone.","feedback_false":"Right to reject it. It increases gradually across the series, but nickel's isotopes break the pattern."}},"s6":{"f":{"mistakes":[{"id":"m1","feedback":"From scandium in the first row to copper in the last, the mass goes up, not down."},{"id":"m2","feedback":"From scandium in the first row to copper in the last, the mass goes up, not down."},{"id":"m3","feedback":"Electrons are not the reason here. The difference is in the nucleus: the atoms differ in their number of neutrons."},{"id":"m4","feedback":"Close: different neutrons cause it, but the blank needs the name for atoms of one element that differ in neutrons."},{"id":"m5","feedback":"All nickel atoms have 28 protons; the atoms differ in their number of neutrons."}],"explanation":"Book point 1, p.12: mass increases gradually; nickel's five stable isotopes average 58.7 u."},"h":{"hints":["Look at the general direction of the mass column.","Nickel atoms differ in their number of neutrons.","Same atomic number, different mass numbers: you met this word with chlorine."]}},"s7":{"exam":{"body":"Nickel is abnormal because it has **five stable isotopes** with **average mass 58.7 u**.","title":"Give reasons: the atomic mass of nickel is less than that of cobalt"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"شك منطقي، لكن كل كتب البيانات بتدّي نفس القيمة: الـ atomic mass بتعتمد على الـ neutrons كمان، مش على الـ protons لوحدها."},{"id":"b","feedback":"تفكير حلو. إنت قابلت الـ average atomic mass قبل كده مع الـ isotopes. الدرس ده بيطبّقها على الـ nickel."},{"id":"c","feedback":"الـ Z بيعدّ الـ protons: الـ nickel عنده 28 والـ cobalt عنده 27، يعني الـ nickel عنده أكتر. الكتلة الأقل جاية من خليط الـ isotopes بتاعه، اللي بتختلف في عدد الـ neutrons."}],"explanation":"الـ atomic mass هي متوسط كتلة الـ isotopes بتاعة العنصر. الـ nickel عنده خمس stable isotopes متوسط كتلتهم 58.7 u، وده أقل من الـ cobalt، مع إن الـ nickel عنده proton زيادة."}},"s3":{"m":{"statement":"الـ 58.7 بتاعة الـ nickel غلطة مطبعية.","correction":"دي متوسط حقيقي، محسوب على قد انتشار كل isotope. أما الـ cobalt الطبيعي فكله cobalt-59، عشان كده قيمته 58.9."}},"s4":{"ok":{"body":"58.7: دي القيمة اللي في الكتاب. أغلب الـ nickel هو الـ nickel-58 الخفيف، وده اللي مخلّي المتوسط أقل من الـ 58.9 بتاعة الـ cobalt."}},"s5":{"q":{"options":[{"id":"a","feedback":"صح. أغلب ذرات الـ argon هي الـ isotope التقيل argon-40، فمتوسط الـ argon بيطلع أعلى، زي ما حصل مع الـ cobalt والـ nickel."},{"id":"b","feedback":"ده نفس فخ الـ nickel: الـ atomic mass متوسط على الـ isotopes، مش عدد للـ protons."},{"id":"c","feedback":"الـ Z بيدّيك عدد الـ protons: 19 للـ potassium و18 للـ argon، يعني الـ potassium عنده أكتر. الفرق في الكتلة جاي من خليط الـ isotopes."}],"explanation":"الـ atomic mass متوسط على الـ isotopes بتاعة العنصر، فهي بتعتمد على خليط الـ isotopes، مش على عدد الـ protons لوحده. أغلب ذرات الـ argon هي argon-40، وده بيرفع متوسط الـ argon فوق الـ potassium."},"tf":{"explanation":"الـ Atomic number بيعدّ الـ protons. أما الـ Atomic mass فهي المتوسط على الـ isotopes، فالاتنين مش لازم يزيدوا مع بعض.","feedback_true":"الـ cobalt والـ nickel بيكسروا القاعدة دي: الـ atomic mass متوسط على الـ isotopes، فبتعتمد على الـ neutrons كمان، مش على الـ protons لوحدها.","feedback_false":"صح إنك رفضتها. هي بتزيد تدريجيًا على طول الـ series، لكن الـ isotopes بتاعة الـ nickel بتكسر النمط."}},"s6":{"f":{"mistakes":[{"id":"m1","feedback":"في الجدول، كتلة الـ copper (آخر صف) أكبر من كتلة الـ scandium (أول صف)، فالكتلة مش بتقل."},{"id":"m2","feedback":"في الجدول، كتلة الـ copper (آخر صف) أكبر من كتلة الـ scandium (أول صف)، فالكتلة مش بتقل."},{"id":"m3","feedback":"الـ electrons مش هما السبب هنا. الفرق في الـ nucleus: ذرات نفس العنصر بتختلف في الكتلة لأنها بتختلف في عدد الـ neutrons."},{"id":"m4","feedback":"قربت: الاختلاف في الـ neutrons هو السبب، لكن الفراغ محتاج اسم ذرات العنصر الواحد اللي بتختلف في الـ neutrons، مش اسم الجسيم نفسه."},{"id":"m5","feedback":"كل ذرات الـ nickel فيها 28 protons، فالـ protons مش هي اللي بتختلف بين ذراته؛ اللي بيختلف هو عدد الـ neutrons."}],"explanation":"النقطة 1 في الكتاب، صفحة 12: الكتلة بتزيد تدريجيًا؛ والـ nickel ليه خمس stable isotopes متوسطهم 58.7 u."},"h":{"hints":["بص على الاتجاه العام لعمود الكتلة.","ذرات الـ nickel بتختلف في عدد الـ neutrons.","نفس الـ atomic number، و mass numbers مختلفة: إنت قابلت الكلمة دي مع الـ chlorine."]}},"s7":{"exam":{"body":"الـ nickel شاذ عشان عنده **five stable isotopes** و**average mass 58.7 u**.","title":"علّل: الـ atomic mass بتاعة الـ nickel أقل من الـ cobalt"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":1,"lesson_no":5,"lesson_count":9,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":31.8,"end_s":108,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.atomic-mass-trend","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Atomic mass: why nickel is abnormal","duration_s":48.78,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary 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3, atoms clearly shrink from Na to Cl. From Sc to Cu, each atom also gains one proton."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Shrink or stay?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Book point 2: the atomic radius changes **little** across the first transition series."},"children":[]},"ch":{"type":"Chart","props":{"kind":"line","series":[{"name":"Atomic radius","points":[{"x":"Sc","y":1.44},{"x":"Ti","y":1.32},{"x":"V","y":1.22},{"x":"Cr","y":1.17},{"x":"Mn","y":1.17},{"x":"Fe","y":1.16},{"x":"Co","y":1.16},{"x":"Ni","y":1.15},{"x":"Cu","y":1.17}]}],"caption":"Atomic radius from Sc to Cu (book's table, p.12, for illustration only)","x_label":"Element (Sc → Cu)","y_label":"Atomic radius","highlight":["Cr","Mn","Fe","Co","Ni","Cu"],"annotations":[{"x":"Cr","text":"nearly constant from here"}]},"children":[]},"t2":{"type":"Text","props":{"content":"From Cr to Cu it is **nearly constant**: 1.17, 1.17, 1.16, 1.16, 1.15, 1.17."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["ch","t","t2"]}}},"title":"The atomic radius column"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"From Sc to Cr, the effective nuclear charge increases. The nuclear attraction to electrons increases."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"pull","from":"z"},{"to":"r","from":"pull"}],"nodes":[{"id":"z","label":"Effective nuclear charge increases"},{"id":"pull","label":"Nuclear attraction to electrons increases"},{"id":"r","label":"Atomic radius **decreases**"}],"layout":"vertical","caption":"Factor 1 from Sc to Cr"},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Effective nuclear charge","definition":"The pull of the nucleus that the outer electrons actually feel."},"children":[]},"t2":{"type":"Text","props":{"content":"This factor **decreases** the atomic radius. Acting alone, it would keep shrinking the atoms."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["kt","t","t2","fd"]}}},"title":"Factor 1: a stronger pull"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"-10 -26 380 270\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"180\" cy=\"110\" r=\"62\" fill=\"#60a5fa\" fill-opacity=\"0.15\" stroke=\"#60a5fa\" stroke-width=\"2\"/><circle cx=\"180\" cy=\"110\" r=\"9\" fill=\"#f87171\"/><line x1=\"86.0\" y1=\"75.8\" x2=\"118.0\" y2=\"87.4\" stroke=\"#fbbf24\" stroke-width=\"3\" stroke-linecap=\"round\"/><polygon points=\"118.0,87.4 109.0,88.3 111.7,81.0\" fill=\"#fbbf24\"/><line x1=\"274.0\" y1=\"75.8\" x2=\"242.0\" y2=\"87.4\" stroke=\"#fbbf24\" stroke-width=\"3\" stroke-linecap=\"round\"/><polygon points=\"242.0,87.4 248.3,81.0 251.0,88.3\" fill=\"#fbbf24\"/><line x1=\"242.0\" y1=\"132.6\" x2=\"275.8\" y2=\"144.9\" stroke=\"#4ade80\" stroke-width=\"3\" stroke-linecap=\"round\"/><polygon points=\"275.8,144.9 266.9,145.8 269.6,138.4\" fill=\"#4ade80\"/><line x1=\"118.0\" y1=\"132.6\" x2=\"84.2\" y2=\"144.9\" stroke=\"#4ade80\" stroke-width=\"3\" stroke-linecap=\"round\"/><polygon points=\"84.2,144.9 90.4,138.4 93.1,145.8\" fill=\"#4ade80\"/><text x=\"180\" y=\"-6\" text-anchor=\"middle\" font-size=\"14\" fill=\"#fbbf24\">1. nuclear attraction increases: radius smaller</text><text x=\"180\" y=\"236\" text-anchor=\"middle\" font-size=\"14\" fill=\"#4ade80\">2. 3d repulsion increases: radius larger</text></svg>","caption":"Two opposite factors act on the size of the atom","max_width":380},"children":[]},"t":{"type":"Text","props":{"content":"From Sc to Cu, the number of 3d electrons grows from 1 to 10. More 3d electrons repel each other more."},"children":[]},"t2":{"type":"Text","props":{"content":"This factor **increases** the atomic radius. The two factors oppose each other, so the radius stays relatively constant."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","t","t2"]}}},"title":"Factor 2: 3d electrons repel"},{"id":"s5","kind":"interact","spec":{"root":"root","state":{"k":1},"elements":{"t":{"type":"Text","props":{"content":"Move from Sc to Cu. Watch the 3d electrons grow while the atom stops shrinking."},"children":[]},"d1":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 190\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"180\" cy=\"88\" r=\"79.2\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-dasharray=\"5 5\"/><circle cx=\"180\" cy=\"88\" r=\"79.2\" fill=\"#60a5fa\" fill-opacity=\"0.22\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><circle cx=\"180\" cy=\"88\" r=\"6\" fill=\"#f87171\"/><text x=\"180\" y=\"120\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">Sc</text><text x=\"10\" y=\"12\" font-size=\"12\" fill=\"#94a3b8\">dashed circle = Sc</text></svg>","caption":"$\\ce{Sc}$: $[\\text{Ar}]\\ 4s^2\\ 3d^1$. The first element: the largest radius here.","max_width":320},"visible":{"eq":1,"$state":"/k"},"children":[]},"d2":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 190\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"180\" cy=\"88\" r=\"79.2\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-dasharray=\"5 5\"/><circle cx=\"180\" cy=\"88\" r=\"72.6\" fill=\"#60a5fa\" fill-opacity=\"0.22\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><circle cx=\"180\" cy=\"88\" r=\"6\" fill=\"#f87171\"/><text x=\"180\" y=\"120\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">Ti</text><text x=\"10\" y=\"12\" font-size=\"12\" fill=\"#94a3b8\">dashed circle = Sc</text></svg>","caption":"$\\ce{Ti}$: $[\\text{Ar}]\\ 4s^2\\ 3d^2$. The pull wins: the radius falls.","max_width":320},"visible":{"eq":2,"$state":"/k"},"children":[]},"d3":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 190\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"180\" cy=\"88\" r=\"79.2\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-dasharray=\"5 5\"/><circle cx=\"180\" cy=\"88\" r=\"67.1\" fill=\"#60a5fa\" fill-opacity=\"0.22\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><circle cx=\"180\" cy=\"88\" r=\"6\" fill=\"#f87171\"/><text x=\"180\" y=\"120\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">V</text><text x=\"10\" y=\"12\" font-size=\"12\" fill=\"#94a3b8\">dashed circle = Sc</text></svg>","caption":"$\\ce{V}$: $[\\text{Ar}]\\ 4s^2\\ 3d^3$. The pull wins: the radius falls.","max_width":320},"visible":{"eq":3,"$state":"/k"},"children":[]},"d4":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 190\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"180\" cy=\"88\" r=\"79.2\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-dasharray=\"5 5\"/><circle cx=\"180\" cy=\"88\" r=\"64.3\" fill=\"#60a5fa\" fill-opacity=\"0.22\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><circle cx=\"180\" cy=\"88\" r=\"6\" fill=\"#f87171\"/><text x=\"180\" y=\"120\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">Cr</text><text x=\"10\" y=\"12\" font-size=\"12\" fill=\"#94a3b8\">dashed circle = Sc</text></svg>","caption":"$\\ce{Cr}$: $[\\text{Ar}]\\ 4s^1\\ 3d^5$. The two factors start to balance.","max_width":320},"visible":{"eq":4,"$state":"/k"},"children":[]},"d5":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 190\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"180\" cy=\"88\" r=\"79.2\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-dasharray=\"5 5\"/><circle cx=\"180\" cy=\"88\" r=\"64.3\" fill=\"#60a5fa\" fill-opacity=\"0.22\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><circle cx=\"180\" cy=\"88\" r=\"6\" fill=\"#f87171\"/><text x=\"180\" y=\"120\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">Mn</text><text x=\"10\" y=\"12\" font-size=\"12\" fill=\"#94a3b8\">dashed circle = Sc</text></svg>","caption":"$\\ce{Mn}$: $[\\text{Ar}]\\ 4s^2\\ 3d^5$. The two factors balance: nearly constant.","max_width":320},"visible":{"eq":5,"$state":"/k"},"children":[]},"d6":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 190\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"180\" cy=\"88\" r=\"79.2\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-dasharray=\"5 5\"/><circle cx=\"180\" cy=\"88\" r=\"63.8\" fill=\"#60a5fa\" fill-opacity=\"0.22\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><circle cx=\"180\" cy=\"88\" r=\"6\" fill=\"#f87171\"/><text x=\"180\" y=\"120\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">Fe</text><text x=\"10\" y=\"12\" font-size=\"12\" fill=\"#94a3b8\">dashed circle = Sc</text></svg>","caption":"$\\ce{Fe}$: $[\\text{Ar}]\\ 4s^2\\ 3d^6$. The two factors balance: nearly constant.","max_width":320},"visible":{"eq":6,"$state":"/k"},"children":[]},"d7":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 190\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"180\" cy=\"88\" r=\"79.2\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-dasharray=\"5 5\"/><circle cx=\"180\" cy=\"88\" r=\"63.8\" fill=\"#60a5fa\" fill-opacity=\"0.22\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><circle cx=\"180\" cy=\"88\" r=\"6\" fill=\"#f87171\"/><text x=\"180\" y=\"120\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">Co</text><text x=\"10\" y=\"12\" font-size=\"12\" fill=\"#94a3b8\">dashed circle = Sc</text></svg>","caption":"$\\ce{Co}$: $[\\text{Ar}]\\ 4s^2\\ 3d^7$. The two factors balance: nearly constant.","max_width":320},"visible":{"eq":7,"$state":"/k"},"children":[]},"d8":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 190\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"180\" cy=\"88\" r=\"79.2\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-dasharray=\"5 5\"/><circle cx=\"180\" cy=\"88\" r=\"63.2\" fill=\"#60a5fa\" fill-opacity=\"0.22\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><circle cx=\"180\" cy=\"88\" r=\"6\" fill=\"#f87171\"/><text x=\"180\" y=\"120\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">Ni</text><text x=\"10\" y=\"12\" font-size=\"12\" fill=\"#94a3b8\">dashed circle = Sc</text></svg>","caption":"$\\ce{Ni}$: $[\\text{Ar}]\\ 4s^2\\ 3d^8$. The two factors balance: nearly constant.","max_width":320},"visible":{"eq":8,"$state":"/k"},"children":[]},"d9":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 190\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"180\" cy=\"88\" r=\"79.2\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-dasharray=\"5 5\"/><circle cx=\"180\" cy=\"88\" r=\"64.3\" fill=\"#60a5fa\" fill-opacity=\"0.22\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><circle cx=\"180\" cy=\"88\" r=\"6\" fill=\"#f87171\"/><text x=\"180\" y=\"120\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">Cu</text><text x=\"10\" y=\"12\" font-size=\"12\" fill=\"#94a3b8\">dashed circle = Sc</text></svg>","caption":"$\\ce{Cu}$: $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$. The two factors balance: nearly constant.","max_width":320},"visible":{"eq":9,"$state":"/k"},"children":[]},"e1":{"type":"Stat","props":{"tone":"warning","label":"electrons in 3d","value":"1"},"children":[]},"e2":{"type":"Stat","props":{"tone":"warning","label":"electrons in 3d","value":"2"},"children":[]},"e3":{"type":"Stat","props":{"tone":"warning","label":"electrons in 3d","value":"3"},"children":[]},"e4":{"type":"Stat","props":{"tone":"warning","label":"electrons in 3d","value":"5"},"children":[]},"e5":{"type":"Stat","props":{"tone":"warning","label":"electrons in 3d","value":"5"},"children":[]},"e6":{"type":"Stat","props":{"tone":"warning","label":"electrons in 3d","value":"6"},"children":[]},"e7":{"type":"Stat","props":{"tone":"warning","label":"electrons in 3d","value":"7"},"children":[]},"e8":{"type":"Stat","props":{"tone":"warning","label":"electrons in 3d","value":"8"},"children":[]},"e9":{"type":"Stat","props":{"tone":"warning","label":"electrons in 3d","value":"10"},"children":[]},"r1":{"type":"Stat","props":{"tone":"brand","label":"atomic radius (book)","value":"1.44"},"children":[]},"r2":{"type":"Stat","props":{"tone":"brand","label":"atomic radius (book)","value":"1.32"},"children":[]},"r3":{"type":"Stat","props":{"tone":"brand","label":"atomic radius (book)","value":"1.22"},"children":[]},"r4":{"type":"Stat","props":{"tone":"brand","label":"atomic radius (book)","value":"1.17"},"children":[]},"r5":{"type":"Stat","props":{"tone":"brand","label":"atomic radius (book)","value":"1.17"},"children":[]},"r6":{"type":"Stat","props":{"tone":"brand","label":"atomic radius (book)","value":"1.16"},"children":[]},"r7":{"type":"Stat","props":{"tone":"brand","label":"atomic radius (book)","value":"1.16"},"children":[]},"r8":{"type":"Stat","props":{"tone":"brand","label":"atomic radius (book)","value":"1.15"},"children":[]},"r9":{"type":"Stat","props":{"tone":"brand","label":"atomic radius (book)","value":"1.17"},"children":[]},"s1":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"visible":{"eq":1,"$state":"/k"},"children":["r1","e1"]},"s2":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"visible":{"eq":2,"$state":"/k"},"children":["r2","e2"]},"s3":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"visible":{"eq":3,"$state":"/k"},"children":["r3","e3"]},"s4":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"visible":{"eq":4,"$state":"/k"},"children":["r4","e4"]},"s5":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"visible":{"eq":5,"$state":"/k"},"children":["r5","e5"]},"s6":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"visible":{"eq":6,"$state":"/k"},"children":["r6","e6"]},"s7":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"visible":{"eq":7,"$state":"/k"},"children":["r7","e7"]},"s8":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"visible":{"eq":8,"$state":"/k"},"children":["r8","e8"]},"s9":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"visible":{"eq":9,"$state":"/k"},"children":["r9","e9"]},"sl":{"type":"Slider","props":{"max":9,"min":1,"step":1,"label":"element (1 = Sc … 9 = Cu)","value":{"$bindState":"/k"}},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["t","sl","d1","s1","d2","s2","d3","s3","d4","s4","d5","s5","d6","s6","d7","s7","d8","s8","d9","s9"]}}},"title":"Watch the size"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Keep decreasing, as across period 3","correct":true},{"id":"b","text":"Stay nearly constant, as in the table","correct":false},{"id":"c","text":"Increase","correct":false}],"question":"Imagine the 3d electrons did not repel each other. What would the radius do from Cr to Cu?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Across the first transition series, the atomic radius falls sharply, as it does across period 3."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Remove one factor"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"o":{"type":"Ordering","props":{"items":[{"id":"a","text":"The effective nuclear charge increases, so the nuclear attraction to electrons increases"},{"id":"b","text":"This first factor would decrease the atomic radius"},{"id":"c","text":"But the number of 3d electrons increases, so the repulsion between them increases, which would increase the radius"},{"id":"d","text":"These two opposite factors balance, so the atomic radius is nearly constant"}],"prompt":"Give reasons: the atomic radius is nearly constant from Cr to Cu. Put the answer in order."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o"]}}},"title":"Build the exam answer"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["The atomic radius changes little; it is nearly constant from Cr to Cu.","Effective nuclear charge increases: the radius tends to decrease.","More 3d electrons repel more: the radius tends to increase.","The book adds: this explains their use in making alloys. An alloy is a metal mixed with other elements; you will study it later."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["anst"]},"anst":{"type":"Text","props":{"content":"Each extra proton raises the effective nuclear charge, which would decrease the radius. But the number of 3d electrons grows too, and their repulsion would increase the radius. The two opposite factors balance, so the radius is nearly constant from Cr to Cu."},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Give reasons"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why these atoms stop shrinking, though each gains a proton?"},"children":[]}}},"title":"Summary"}],"title":"Atomic radius: nearly constant","minutes":8,"book_ref":"Ch.1 The general properties of the first transition elements, point 2, pp.12-13","subtitle":"Two opposite factors in balance","objectives":["Read the atomic radius column: little change across the series, nearly constant from Cr to Cu.","Explain it with the book's two opposite factors: effective nuclear charge and repulsion between 3d electrons.","Contrast it with the clear decrease across a period of representative elements."],"concept_ids":["te.atomic-radius"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"A natural guess: more protons pull harder. But the pull is not the only thing that grows here: the repulsion between the 3d electrons grows too."},{"id":"b","feedback":"Good prediction. The book's table agrees. This lesson shows why."},{"id":"c","feedback":"More protons pull the electrons in, so that pull alone cannot make the atom clearly bigger."}],"explanation":"From Cr to Cu the atomic radius stays nearly constant: the growing nuclear attraction is opposed by the growing repulsion between the 3d electrons."}},"s6":{"q":{"options":[{"id":"a","feedback":"Right. Only the growing nuclear attraction would act, so the atoms would keep shrinking."},{"id":"b","feedback":"A constant radius needs two factors in balance, and this question removed one of them, the 3d repulsion."},{"id":"c","feedback":"The factor that makes the radius larger is the 3d repulsion, and this imagined case removes it."}],"explanation":"Without the repulsion between the 3d electrons, the growing nuclear attraction would act alone, so the radius would keep decreasing, as across period 3."},"tf":{"explanation":"Book point 2: little change in atomic radii; nearly constant from Cr to Cu.","feedback_true":"From Cr to Cu the radius stays nearly constant, because the growing 3d repulsion slows the shrinking.","feedback_false":"Right to reject it. The change is little, because 3d repulsion opposes the growing nuclear attraction."}},"s7":{"o":{"items":[{"id":"a","feedback":"This line gives a factor, the growing nuclear attraction, not the result."},{"id":"b","feedback":"'This first factor' points back to the nuclear attraction, so that factor has to be named already."},{"id":"c","feedback":"The word 'But' turns to the opposite factor, so the factor it opposes has to be given already."},{"id":"d","feedback":"Saying the two factors balance needs both factors given already."}],"explanation":"Factor 1 (nuclear attraction, radius smaller) → factor 2 (3d repulsion, radius larger) → balance → nearly constant radius."}},"s8":{"exam":{"body":"Two **opposite factors**: the **effective nuclear charge increases** (radius decreases), while the **repulsion between 3d electrons increases** (radius increases). So the atomic radius is **relatively constant**."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"توقّع منطقي: protons أكتر يعني شدّ أقوى. لكن الشدّ مش الحاجة الوحيدة اللي بتزيد هنا: التنافر بين الـ 3d electrons بيزيد كمان."},{"id":"b","feedback":"توقّع حلو. وجدول الكتاب بيقول كده برضه. الدرس ده هيوريك ليه."},{"id":"c","feedback":"الـ protons الزيادة بتشد الـ electrons لجوّه، والشدّ ده لوحده بيصغّر الذرة، مش بيكبّرها."}],"explanation":"من الـ Cr للـ Cu الـ atomic radius بيفضل ثابت تقريبًا: الـ nuclear attraction اللي بتزيد بيعاكسها التنافر اللي بيزيد بين الـ 3d electrons."}},"s6":{"q":{"options":[{"id":"a","feedback":"صح. ساعتها مفيش غير الـ nuclear attraction اللي بتزيد هي اللي شغّالة، فالذرات هتفضل تصغر."},{"id":"b","feedback":"الـ radius الثابت تقريبًا محتاج عاملين متوازنين، والسؤال ده شال واحد منهم: التنافر بين الـ 3d electrons."},{"id":"c","feedback":"العامل اللي بيكبّر الـ radius هو التنافر بين الـ 3d electrons، والحالة اللي بنتخيّلها دي شالته، فمفيش حاجة تكبّر الذرة."}],"explanation":"من غير التنافر بين الـ 3d electrons، الـ nuclear attraction اللي بتزيد هتشتغل لوحدها، فالـ radius هيفضل يقل، زي ما بيحصل في period 3."},"tf":{"explanation":"النقطة 2 في الكتاب: الـ atomic radii بتتغيّر تغيير بسيط، ومن الـ Cr للـ Cu ثابتة تقريبًا.","feedback_true":"من الـ Cr للـ Cu الـ radius بيفضل ثابت تقريبًا، عشان التنافر بين الـ 3d electrons بيبطّأ تصغير الذرة.","feedback_false":"صح إنك رفضتها. التغيير بسيط، عشان التنافر بين الـ 3d electrons بيعاكس الـ nuclear attraction اللي بتزيد."}},"s7":{"o":{"items":[{"id":"a","feedback":"السطر ده عامل، مش نتيجة، والعوامل لازم تتذكر قبل النتيجة."},{"id":"b","feedback":"'this first factor' بترجع على عامل، فالعامل ده لازم يكون اتذكر قبلها."},{"id":"c","feedback":"كلمة 'But' بتلف للعامل العكسي، فلازم ييجي قبلها العامل الأول وأثره على الـ radius."},{"id":"d","feedback":"مينفعش تقول إن العاملين بيوازنوا بعض قبل ما الاتنين يتذكروا."}],"explanation":"العامل 1 (الـ nuclear attraction، الـ radius يصغر) → العامل 2 (التنافر بين الـ 3d electrons، الـ radius يكبر) → توازن → radius ثابت تقريبًا."}},"s8":{"exam":{"body":"فيه **عاملين عكس بعض**: الـ **effective nuclear charge بتزيد** (فالـ radius يصغر)، وفي نفس الوقت الـ **repulsion بين الـ 3d electrons بيزيد** (فالـ radius يكبر). عشان كده الـ atomic radius بيفضل **ثابت نسبيًا**."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":2,"lesson_no":6,"lesson_count":9,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":115.8,"end_s":205,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.atomic-radius","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Atomic radius: nearly constant","duration_s":49.86,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"4","relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.metallic-properties","kind":"lesson","version":3,"catalog_version":3,"ord":249,"primary_concept_id":"te.metallic-properties","concepts":[{"concept_id":"te.metallic-properties","role":"primary"}],"title":"The metallic property","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Yes: all are unreactive, like copper","correct":false},{"id":"b","text":"Yes: all react strongly, even with water","correct":false},{"id":"c","text":"No: their activity varies","correct":true}],"question":"Predict: do the transition metals all have the same chemical activity?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Copper water pipes can last for decades. 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Moderate activity.","max_width":320},"visible":{"eq":2,"$state":"/m"},"children":[]},"d3":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 300 200\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><path d=\"M70,20 L70,170 Q70,180 80,180 L220,180 Q230,180 230,170 L230,20\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><rect x=\"72\" y=\"60\" width=\"156\" height=\"118\" fill=\"#60a5fa\" fill-opacity=\"0.18\"/><rect x=\"125\" y=\"150\" width=\"50\" height=\"22\" rx=\"4\" fill=\"#d97706\" stroke=\"#e2e8f0\" stroke-width=\"1.5\"/><text x=\"150\" y=\"110\" text-anchor=\"middle\" font-size=\"13\" fill=\"#94a3b8\">no change</text></svg>","caption":"Copper in water: no change. Limited chemical activity.","max_width":320},"visible":{"eq":3,"$state":"/m"},"children":[]},"m2":{"type":"Misconception","props":{},"visible":{"eq":3,"$state":"/m"},"children":[]},"sl":{"type":"Slider","props":{"max":3,"min":1,"step":1,"label":"metal (1 = Sc, 2 = Fe, 3 = Cu)","value":{"$bindState":"/m"}},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["t","sl","d1","d2","d3","m2"]}}},"title":"Three metals, three behaviours"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"sol","text":"Solid"},{"id":"con","text":"Good conductor of electricity"},{"id":"wat","text":"Replaces the hydrogen of water"},{"id":"lus","text":"Metallic luster"},{"id":"rus","text":"Goes rusty when exposed to air"},{"id":"heat","text":"Good conductor of heat"}],"answer":{"all":["sol","con","lus","heat"],"var":["wat","rus"]},"prompt":"Sort each property of the first transition series.","categories":[{"id":"all","label":"All of them share it"},{"id":"var","label":"It varies from metal to metal"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c"]}}},"title":"Shared or varies?"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"o":{"type":"Ordering","props":{"items":[{"id":"sc","text":"Scandium"},{"id":"fe","text":"Iron"},{"id":"cu","text":"Copper"}],"prompt":"Rank the book's three examples by chemical activity, most active first."},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Scandium replaces the hydrogen of water strongly","correct":true},{"id":"b","text":"All of them are good conductors of electricity","correct":false},{"id":"c","text":"Copper has metallic luster","correct":false}],"question":"A student says: \"Copper hardly reacts, so all transition metals are unreactive.\" Which book fact shows the mistake?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o","q"]}}},"title":"Rank and reason"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["All of them are solids with metallic luster and good conductivity of heat and electricity.","Their chemical activity varies: copper limited, iron moderate (goes rusty in air), scandium highly active.","Next in point 3: high melting points and high density, and why."]},"children":[]},"ans":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Why copper pipes last while an iron gate rusts"}},"children":["ans_t","ans_tb"]},"exam":{"type":"Callout","props":{"variant":"exam","ui_labels":{"callout.exam":"Describe"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","ans"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why copper pipes last while an iron gate rusts?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"Their chemical activity varies: copper has limited activity, so the pipes last; iron is moderate, so it goes rusty when exposed to air."},"children":[]},"ans_tb":{"type":"DataTable","props":{"rows":[["Copper","limited","no change in water"],["Iron","moderate","goes rusty in moist air"],["Scandium","highly active","replaces the hydrogen of water strongly"]],"headers":["Metal","Chemical activity","What it does"]},"children":[]}}},"title":"Summary"}],"title":"The metallic property","minutes":7,"book_ref":"Ch.1 The general properties of the first transition elements, point 3 (a, d), p.13","subtitle":"Shared looks, different activity","objectives":["State that all first-series transition elements are solids with metallic luster and good conductivity of heat and electricity.","Describe the variation in their chemical activity: copper limited, iron moderate, scandium highly active.","Tell apart the properties they all share from the ones that vary."],"concept_ids":["te.metallic-properties"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Copper is one member only, and the iron gate in the hook goes rusty in air."},{"id":"b","feedback":"Then copper pipes would not last long in water, yet they do: copper has limited chemical activity."},{"id":"c","feedback":"Good prediction. The book gives three examples. Let's see them."}],"explanation":"Their chemical activity varies. The book's examples: copper has limited chemical activity, iron is moderate (it goes rusty in air), and scandium is highly active (it replaces the hydrogen of water strongly)."}},"s3":{"m":{"statement":"Transition metals are unreactive, like copper.","correction":"Copper is just one member. Scandium replaces the hydrogen of water strongly: their activity varies."}},"s4":{"m2":{"statement":"All transition metals react strongly with water.","correction":"Copper shows this is false: in water it does not change. The activity varies from metal to metal."}},"s5":{"c":{"items":[{"id":"sol","feedback":"No metal from Sc to Cu is a liquid or a gas."},{"id":"con","feedback":"Copper, iron and scandium do not differ in this: each is a good conductor of electricity."},{"id":"wat","feedback":"Scandium replaces the hydrogen of water strongly, while copper has limited chemical activity."},{"id":"lus","feedback":"A clean piece of any of them shows metallic luster."},{"id":"rus","feedback":"Going rusty is chemical activity, and the book's examples differ in it: copper's activity is limited."},{"id":"heat","feedback":"Each of these metals is a good conductor of heat."}],"explanation":"Shared (point 3a): solid, metallic luster, good conductors of heat and electricity. Varies (point 3d): chemical activity."}},"s6":{"o":{"items":[{"id":"sc","feedback":"Scandium replaces the hydrogen of water strongly: it is highly active."},{"id":"fe","feedback":"Iron goes rusty in moist air: its activity is moderate."},{"id":"cu","feedback":"Copper has limited chemical activity."}],"explanation":"Scandium (highly active) → iron (moderate) → copper (limited)."},"q":{"options":[{"id":"a","feedback":"Right. One highly active member is enough to break the claim."},{"id":"b","feedback":"That is a shared physical property; it says nothing about how they react."},{"id":"c","feedback":"Luster is about the look of the surface, not about chemical activity."}],"explanation":"Scandium replaces the hydrogen of water strongly, so at least one transition metal is highly active and the claim fails. Conductivity and luster are physical properties; they say nothing about chemical activity."}},"s7":{"exam":{"body":"There is **variation in their activity**. **Copper** has limited activity; **iron** is moderate (goes rusty if exposed to air). **Scandium** is highly active (replaces hydrogen of water strongly)."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ copper ده مجرد عنصر واحد من السلسلة، وبوابة الـ iron اللي في أول الدرس بتصدّي لما تتعرّض للهوا."},{"id":"b","feedback":"لو كده، مواسير الـ copper مكانتش هتعمّر كتير في الماية، لكن الـ copper نشاطه محدود."},{"id":"c","feedback":"توقّع حلو. الكتاب بيدي تلات أمثلة، يلا نشوفهم."}],"explanation":"الـ chemical activity بتاعتهم بتختلف. أمثلة الكتاب: الـ copper نشاطه محدود، والـ iron متوسط (بيصدّي لو اتعرّض للهوا)، والـ scandium نشاطه عالي (بيحل محل الـ hydrogen بتاع الماية بقوة)."}},"s3":{"m":{"statement":"الـ transition metals مش نشطة، زي الـ copper.","correction":"الـ copper ده مجرد عنصر واحد منهم. الـ scandium بيحل محل الـ hydrogen بتاع المية بقوة: يعني نشاطهم بيختلف."}},"s4":{"m2":{"statement":"كل الـ transition metals بتتفاعل مع المية بقوة.","correction":"الـ copper بيبيّن إن ده مش صح: في المية مابيحصلوش أي تغيير. النشاط بيختلف من metal للتاني."}},"s5":{"c":{"items":[{"id":"sol","feedback":"كل الـ metals من الـ Sc لحد الـ Cu بتبقى solid، مفيش فيهم liquid ولا gas."},{"id":"con","feedback":"الـ copper والـ iron والـ scandium كلهم موصّلين كويسين للكهربا."},{"id":"wat","feedback":"الـ scandium بيحل محل الـ hydrogen بتاع الماية بقوة، والـ copper نشاطه محدود."},{"id":"lus","feedback":"أي حتة نضيفة من أي واحد فيهم ليها metallic luster."},{"id":"rus","feedback":"الصدأ ظهر في مثال الـ iron تحديدًا، مش في كل metals السلسلة."},{"id":"heat","feedback":"كل الـ metals دي بتوصّل الحرارة كويس."}],"explanation":"المشترك بينهم (البند 3a): solid، و metallic luster، وتوصيل جيد للحرارة والكهربا. اللي بيختلف (البند 3d): الـ chemical activity."}},"s6":{"o":{"items":[{"id":"sc","feedback":"الـ scandium بيتفاعل حتى مع الماية، وبيحل محل الـ hydrogen بتاعها بقوة."},{"id":"fe","feedback":"الـ iron بيتفاعل مع الهوا الرطب ويصدّي، لكن نشاطه متوسط."},{"id":"cu","feedback":"الـ copper الـ chemical activity بتاعته محدودة."}],"explanation":"الأول الـ scandium (نشاطه عالي)، وبعده الـ iron (متوسط)، وبعدين الـ copper (محدود)."},"q":{"options":[{"id":"a","feedback":"صح. عنصر واحد نشاطه عالي كفاية إنه يوقّع الكلام ده."},{"id":"b","feedback":"دي خاصية فيزيائية مشتركة بينهم، ومش بتقول حاجة عن طريقة تفاعلهم."},{"id":"c","feedback":"الـ luster ده بيوصف شكل السطح، مش الـ chemical activity."}],"explanation":"الـ scandium بيحل محل الـ hydrogen بتاع الماية بقوة، يعني فيه transition metal واحد على الأقل نشاطه عالي، والكلام ده بيقع. أما التوصيل والـ luster فدي خواص فيزيائية، ومش بتقول حاجة عن الـ chemical activity."}},"s7":{"exam":{"body":"فيه **اختلاف في نشاطها (variation in their activity)**. الـ **copper** نشاطه محدود؛ والـ **iron** متوسط (بيصدّي لو اتعرّض للهوا). والـ **scandium** نشاطه عالي جدًا (بيحل محل الـ hydrogen بتاع المية بقوة)."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":3,"lesson_no":7,"lesson_count":9,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":223.2,"end_s":299.7,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.metallic-properties","kind":"short","chapter_id":"chem-s3-en.ch1","title":"The metallic property","duration_s":53.31,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-phys.states-melting-boiling","kind":"lesson","version":3,"catalog_version":3,"ord":251,"primary_concept_id":"phys.states-melting-boiling","concepts":[{"concept_id":"phys.states-melting-boiling","role":"primary"}],"title":"States of matter, melting and boiling points","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"How strongly its particles hold each other","correct":true},{"id":"b","text":"The size of the piece","correct":false},{"id":"c","text":"How fast you heat it","correct":false}],"question":"Predict: what decides how high a substance's melting point is?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Ice melts in your hand. 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(ice)","y":0},{"x":"Aluminum","y":660},{"x":"Table salt","y":801}]}],"caption":"Melting points of some familiar substances","x_label":"Substance","y_label":"Melting point"},"children":[]},"t2":{"type":"Text","props":{"content":"So the **stronger the forces** between the particles, the **higher** the melting and boiling points."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["ch","t","t2"]}}},"title":"Stronger forces, higher values"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"A substance melts at 45 °C and boils at 220 °C. At 25 °C, it is a ___ .","answers":[["solid"]],"mistakes":[{"id":"m1","blank":0,"answer":"liquid"},{"id":"m2","blank":0,"answer":"gas"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"B","correct":true},{"id":"b","text":"A","correct":false},{"id":"c","text":"You can't tell without the mass of each sample","correct":false}],"question":"Substance A melts at 45 °C. Substance B melts at 1085 °C. Which has stronger forces between its particles?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","f"]}}},"title":"Read the numbers"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Matter is solid, liquid or gas.","Melting point: solid → liquid. Boiling point: liquid → gas.","Stronger forces between particles → higher melting and boiling points.","Next in Chapter 1: transition metals melt at very high temperatures. Why?"]},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"l","from":"s","label":"melting point (water: 0 °C)"},{"to":"g","from":"l","label":"boiling point (water: 100 °C)"}],"nodes":[{"id":"s","label":"Solid"},{"id":"l","label":"Liquid"},{"id":"g","label":"Gas"}],"layout":"horizontal","caption":"Stronger forces between particles → higher melting and boiling points"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fd","b","self"]},"self":{"type":"Text","props":{"content":"Can you explain why a high melting point means strong forces between particles?"},"children":[]}}},"title":"Summary"}],"title":"States of matter, melting and boiling points","minutes":5,"book_ref":"Background for Ch.1 General properties, point 3b, p.13 (high melting and boiling points)","subtitle":"When a solid lets go","objectives":["Name the three states of matter and the changes between them.","Define the melting point and the boiling point.","Link stronger forces between particles to higher melting and boiling points."],"concept_ids":["phys.states-melting-boiling"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. To melt, the particles must partly break free."},{"id":"b","feedback":"A small ice cube and a big block both melt at 0 °C, so size does not change the melting point."},{"id":"c","feedback":"Fast heating gets there sooner, but it does not change the temperature at which melting starts."}],"explanation":"To melt, the particles must partly break free, so the melting point depends on how strongly they hold each other. The size of the piece and how fast you heat it do not change the temperature at which melting starts."}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"25 °C has not reached the melting point (45 °C) yet."},{"id":"m2","feedback":"25 °C is below both the melting point (45 °C) and the boiling point (220 °C)."}],"explanation":"25 °C is below the melting point (45 °C), so the substance is still solid."},"q":{"options":[{"id":"a","feedback":"Right. Its particles need far more heating to break free, so they hold each other more strongly."},{"id":"b","feedback":"A smaller number means less heating is needed to free the particles, so A has weaker forces, not stronger ones."},{"id":"c","feedback":"A melting point does not depend on how much you have. B's much higher melting point tells you its particles hold each other more strongly."}],"explanation":"B melts at a much higher temperature, so its particles need far more heating to break free: the forces between them are stronger. A melting point does not depend on the mass of the sample."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. عشان المادة تسيح، الـ particles لازم تفلت من بعضها جزئيًا."},{"id":"b","feedback":"مكعب ثلج صغير وقالب ثلج كبير الاتنين بيسيحوا عند 0 °C، يعني الحجم مش بيغيّر الـ melting point."},{"id":"c","feedback":"التسخين السريع بيوصّلك أسرع، لكنه مش بيغيّر درجة الحرارة اللي الـ melting بيبدأ عندها."}],"explanation":"عشان المادة تسيح، الـ particles لازم تفلت من بعضها جزئيًا، فالـ melting point بتعتمد على قد إيه الـ particles ماسكة في بعض. حجم الحتة وسرعة التسخين مش بيغيّروا درجة الحرارة اللي الـ melting بيبدأ عندها."}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"درجة 25 °C لسه ما وصلتش للـ melting point بتاعتها."},{"id":"m2","feedback":"درجة 25 °C ما عدّتش أي واحدة من القيمتين."}],"explanation":"25 °C أقل من الـ melting point (45 °C)، يعني المادة لسه solid."},"q":{"options":[{"id":"a","feedback":"صح. الـ particles بتاعتها محتاجة تسخين أكتر بكتير عشان تفلت، يعني ماسكة في بعضها بقوة أكبر."},{"id":"b","feedback":"رقم أصغر يعني تسخين أقل عشان الـ particles تفلت، يعني الـ forces في A أضعف مش أقوى."},{"id":"c","feedback":"الـ melting point مش بتعتمد على الكمية اللي معاك. الـ melting point العالية بتاعة B معناها إن الـ particles بتاعتها ماسكة في بعض بقوة أكبر."}],"explanation":"الـ B بتسيح عند درجة حرارة أعلى بكتير، يعني الـ particles بتاعتها محتاجة تسخين أكتر بكتير عشان تفلت، فالـ forces بينها أقوى. والـ melting point مش بتعتمد على كتلة العينة."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":1,"is_basics":true,"lesson_no":1,"lesson_count":9,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":307.3,"end_s":370.4,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-phys.states-melting-boiling","kind":"short","chapter_id":"chem-s3-en.ch1","title":"States of matter, melting and boiling points","duration_s":47.9,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-bond.chemical-bond-basic","kind":"lesson","version":2,"catalog_version":3,"ord":253,"primary_concept_id":"bond.chemical-bond-basic","concepts":[{"concept_id":"bond.chemical-bond-basic","role":"primary"}],"title":"Ionic and covalent bonds","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Attraction between a positive ion and a negative ion","correct":true},{"id":"b","text":"A pair of electrons shared by the two atoms","correct":false},{"id":"c","text":"Nothing: they are only mixed","correct":false}],"question":"Predict: what holds sodium and chlorine together in table salt?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Sodium is a soft, reactive metal. Chlorine is a poisonous gas. Together they make table salt."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Metal plus poison gas"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Both ions now have a stable outer level, like a noble gas."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"nap","from":"na","label":"loses 1 electron"},{"to":"clm","from":"cl","label":"gains 1 electron"},{"to":"b","from":"nap"},{"to":"b","from":"clm"}],"nodes":[{"id":"na","label":"Na (2, 8, 1)"},{"id":"nap","label":"$\\ce{Na+}$ (2, 8)"},{"id":"cl","label":"Cl (2, 8, 7)"},{"id":"clm","label":"$\\ce{Cl-}$ (2, 8, 8)"},{"id":"b","label":"$\\ce{Na+}$ and $\\ce{Cl-}$ attract"}],"caption":"Electron transfer in sodium chloride"},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Ionic bond","definition":"The electrostatic attraction between a positive ion and a negative ion, formed by transfer of electrons."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fd","kt","t"]}}},"title":"Ionic bond"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 190\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"130\" cy=\"85\" r=\"70\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><text x=\"130\" y=\"92\" text-anchor=\"middle\" font-size=\"22\" font-weight=\"700\" fill=\"#e2e8f0\">Cl</text><circle cx=\"230\" cy=\"85\" r=\"70\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><text x=\"230\" y=\"92\" text-anchor=\"middle\" font-size=\"22\" font-weight=\"700\" fill=\"#e2e8f0\">Cl</text><ellipse cx=\"180\" cy=\"85\" rx=\"14\" ry=\"26\" fill=\"#fbbf24\" fill-opacity=\"0.18\" stroke=\"#fbbf24\" stroke-width=\"1.5\"/><circle cx=\"180\" cy=\"75\" r=\"5\" fill=\"#fbbf24\"/><circle cx=\"180\" cy=\"95\" r=\"5\" fill=\"#fbbf24\"/><circle cx=\"117.8\" cy=\"16.1\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"95.0\" cy=\"24.4\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"61.1\" cy=\"72.8\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"61.1\" cy=\"97.2\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"95.0\" cy=\"145.6\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"117.8\" cy=\"153.9\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"242.2\" cy=\"16.1\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"265.0\" cy=\"24.4\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"298.9\" cy=\"72.8\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"298.9\" cy=\"97.2\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"265.0\" cy=\"145.6\" r=\"5\" fill=\"#60a5fa\"/><circle cx=\"242.2\" cy=\"153.9\" r=\"5\" fill=\"#60a5fa\"/><text x=\"180\" y=\"176\" text-anchor=\"middle\" font-size=\"13\" fill=\"#fbbf24\">shared pair</text></svg>","caption":"Two chlorine atoms share one pair of electrons in $\\ce{Cl2}$","max_width":360},"children":[]},"t":{"type":"Text","props":{"content":"Each chlorine atom has 7 outer electrons and needs one more. Neither gives one away, so they share a pair."},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Covalent bond","definition":"A bond formed by sharing pairs of electrons between two atoms."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","kt","t"]}}},"title":"Covalent bond"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"mgo","text":"$\\ce{MgO}$: magnesium (metal) and oxygen"},{"id":"h2o","text":"$\\ce{H2O}$: hydrogen and oxygen"},{"id":"kbr","text":"$\\ce{KBr}$: potassium (metal) and bromine"},{"id":"ch4","text":"$\\ce{CH4}$: carbon and hydrogen"},{"id":"o2","text":"$\\ce{O2}$: two oxygen atoms"}],"answer":{"cov":["h2o","ch4","o2"],"ion":["mgo","kbr"]},"prompt":"Sort each substance by the bond between its atoms.","categories":[{"id":"ion","label":"Ionic bond"},{"id":"cov","label":"Covalent bond"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c"]}}},"title":"Transfer or share?"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Ionic bond: one atom gives electrons, the other takes them; the oppositely charged ions attract.","Covalent bond: two atoms share pairs of electrons.","Next: metal atoms bond to each other in a third way, the metallic bond."]},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_tbl","ans_t"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why sodium and chlorine form ions, but two chlorine atoms share?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"Sodium loses its 1 outer electron and chlorine gains it: $\\ce{Na+}$ and $\\ce{Cl-}$ form and attract. Each chlorine atom has 7 outer electrons and needs one more, so two chlorine atoms share a pair."},"children":[]},"ans_tbl":{"type":"DataTable","props":{"rows":[["Na (2, 8, 1) + Cl (2, 8, 7)","Na gives 1 electron to Cl","Ionic bond"],["Cl (2, 8, 7) + Cl (2, 8, 7)","Neither gives one away, so they share a pair","Covalent bond"]],"headers":["Atoms","What happens","Bond"]},"children":[]}}},"title":"Summary"}],"title":"Ionic and covalent bonds","minutes":5,"book_ref":"Background for Ch.1 General properties, point 3b, p.13 (the metallic bond is another kind of chemical bond)","subtitle":"Give electrons or share them","objectives":["Describe the ionic bond: transfer of electrons, then attraction between oppositely charged ions.","Describe the covalent bond: sharing of electron pairs between atoms.","Decide which bond forms in a simple compound."],"concept_ids":["bond.chemical-bond-basic"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. Sodium gives an electron to chlorine. Let's see it."},{"id":"b","feedback":"Sharing happens between two non-metals, and sodium is a metal: it gives its electron away."},{"id":"c","feedback":"Salt has new properties, not those of sodium or chlorine, so it is a compound, not a mixture."}],"explanation":"Sodium gives an electron to chlorine, forming a positive sodium ion and a negative chloride ion. The attraction between these opposite ions, the ionic bond, holds table salt together."}},"s4":{"c":{"items":[{"id":"mgo","feedback":"Mg is a metal with 2 outer electrons and O needs 2, so the electrons move across from Mg to O."},{"id":"h2o","feedback":"Both are non-metals and both need electrons, so neither one takes electrons from the other."},{"id":"kbr","feedback":"K is a metal with 1 outer electron, and it gives that electron to bromine, so ions form."},{"id":"ch4","feedback":"Both are non-metals, and neither gives electrons away completely: they share electron pairs."},{"id":"o2","feedback":"Two identical atoms pull equally, so neither one takes electrons from the other."}],"explanation":"Metal + non-metal: electrons transfer, ions form (MgO, KBr). Non-metals together: electron pairs are shared (H₂O, CH₄, O₂)."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. الـ sodium بيدي electron للـ chlorine. يلا نشوف ده."},{"id":"b","feedback":"المشاركة بتحصل بين اتنين non-metals، والـ sodium ده metal."},{"id":"c","feedback":"الملح ليه خواص جديدة، مش خواص الـ sodium ولا الـ chlorine، فده compound مش mixture."}],"explanation":"الـ sodium بيدّي electron للـ chlorine، فيتكوّن positive ion من الـ sodium و negative ion من الـ chlorine. والتجاذب بين الـ ions دي، اللي هو الـ ionic bond، هو اللي ماسك ملح الطعام في بعضه."}},"s4":{"c":{"items":[{"id":"mgo","feedback":"الـ Mg ده metal عنده 2 outer electrons والـ O محتاج 2، فالـ electrons بتنتقل من الـ Mg للـ O."},{"id":"h2o","feedback":"الاتنين non-metals والاتنين محتاجين electrons، فمفيش واحد فيهم بياخد electrons من التاني."},{"id":"kbr","feedback":"الـ K ده metal عنده outer electron واحد، وبيديه للـ bromine فيتكوّنوا ions."},{"id":"ch4","feedback":"الاتنين non-metals، ومفيش واحد فيهم بيدي electrons للتاني بالكامل: بيتشاركوا فيها."},{"id":"o2","feedback":"اتنين atoms متطابقين بيشدوا بنفس القوة، فمفيش واحد فيهم يقدر ياخد electrons من التاني."}],"explanation":"metal + non-metal: الـ electrons بتنتقل والـ ions بتتكوّن (MgO, KBr). non-metals مع بعض: بيتشاركوا في أزواج electrons (H₂O, CH₄, O₂)."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":2,"is_basics":true,"lesson_no":2,"lesson_count":9,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-bond.chemical-bond-basic","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Ionic and covalent bonds: from zero","duration_s":330.64,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-bond.chemical-bond-basic","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Ionic and covalent bonds","duration_s":44.4,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":66,"page_to":66,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-bond.metallic-bond","kind":"lesson","version":3,"catalog_version":3,"ord":255,"primary_concept_id":"bond.metallic-bond","concepts":[{"concept_id":"bond.metallic-bond","role":"primary"}],"title":"Metallic bond","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Each magnesium atom gives more electrons to the bond","correct":true},{"id":"b","text":"Magnesium atoms are much heavier","correct":false},{"id":"c","text":"Magnesium atoms share electron pairs, like $\\ce{Cl2}$","correct":false}],"question":"Predict: why does magnesium hold together so much more strongly?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Sodium melts at 98 °C. Magnesium, the very next element, melts at 650 °C."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Neighbours, very different"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 340 232\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"22\" y=\"12\" width=\"296\" height=\"208\" rx=\"18\" fill=\"#60a5fa\" fill-opacity=\"0.10\" stroke=\"#60a5fa\" stroke-opacity=\"0.35\" stroke-width=\"1.5\"/><circle cx=\"251.5\" cy=\"201.0\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"236.2\" cy=\"197.1\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"40.0\" cy=\"109.4\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"292.4\" cy=\"144.6\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"161.5\" cy=\"67.3\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"182.1\" cy=\"130.2\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"35.6\" cy=\"61.6\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"109.1\" cy=\"195.9\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"243.3\" cy=\"50.6\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"32.5\" cy=\"187.3\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"89.8\" cy=\"61.4\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"303.1\" cy=\"187.5\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"65\" cy=\"50\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"65\" y=\"56\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"135\" cy=\"50\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"135\" y=\"56\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"205\" cy=\"50\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"205\" y=\"56\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"275\" cy=\"50\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"275\" y=\"56\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"65\" cy=\"114\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"65\" y=\"120\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"135\" cy=\"114\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"135\" y=\"120\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"205\" cy=\"114\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"205\" y=\"120\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"275\" cy=\"114\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"275\" y=\"120\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"65\" cy=\"178\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"65\" y=\"184\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"135\" cy=\"178\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"135\" y=\"184\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"205\" cy=\"178\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"205\" y=\"184\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text><circle cx=\"275\" cy=\"178\" r=\"19\" fill=\"#f87171\" fill-opacity=\"0.22\" stroke=\"#f87171\" stroke-width=\"2\"/><text x=\"275\" y=\"184\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#f87171\">+</text></svg>","caption":"Sodium: positive ions in a regular pattern (a crystal lattice), in a sea of free electrons","max_width":360},"children":[]},"t":{"type":"Text","props":{"content":"Each atom releases its valence electrons. They move freely among the ions and hold them together."},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Metallic bond","definition":"The attraction between the positive metal ions and the free valence (outer) electrons around them."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","kt","t"]}}},"title":"A sea of electrons"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"n":1},"elements":{"c":{"type":"Callout","props":{"variant":"tip"},"children":[]},"t":{"type":"Text","props":{"content":"Choose the number of valence electrons each atom releases. Watch the sea and the melting point."},"children":[]},"b1":{"type":"Stat","props":{"tone":"brand","label":"Na boiling point","value":"883 °C"},"children":[]},"b2":{"type":"Stat","props":{"tone":"brand","label":"Mg boiling point","value":"1090 °C"},"children":[]},"b3":{"type":"Stat","props":{"tone":"brand","label":"Al boiling point","value":"2519 °C"},"children":[]},"d1":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 340 232\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"22\" y=\"12\" width=\"296\" height=\"208\" rx=\"18\" fill=\"#60a5fa\" fill-opacity=\"0.10\" stroke=\"#60a5fa\" stroke-opacity=\"0.35\" stroke-width=\"1.5\"/><circle cx=\"242.8\" cy=\"69.0\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"168.7\" cy=\"106.3\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"57.9\" cy=\"25.4\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"242.4\" cy=\"20.4\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"154.9\" cy=\"158.5\" r=\"4\" fill=\"#60a5fa\"/><circle cx=\"95.1\" cy=\"201.5\" 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properties"},"children":[]},"c1t":{"type":"Text","props":{"content":"The free electrons can move through the metal and carry the current."},"children":[]},"c2t":{"type":"Text","props":{"content":"Layers of ions can slide over each other. 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Calcium (2 valence electrons) melts at 842 °C. Which explains the difference?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","f"]}}},"title":"A new pair"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Metallic bond: positive metal ions held together by a sea of free valence electrons.","For neighbours such as Na, Mg and Al: more free electrons per atom → stronger bond → higher melting and boiling points.","The free electrons conduct electricity; sliding layers make metals easy to shape.","Next in Chapter 1: in transition metals, both 4s and 3d electrons can join this bond."]},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Na",1,"98 °C","883 °C"],["Mg",2,"650 °C","1090 °C"],["Al",3,"660 °C","2519 °C"]],"caption":"Na, Mg, Al: more free electrons, higher melting and boiling points","headers":["Metal","Valence electrons per atom","Melting point","Boiling point"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tb","self"]},"self":{"type":"Text","props":{"content":"Can you explain why magnesium melts at a much higher temperature than sodium?"},"children":[]}}},"title":"Summary"}],"title":"Metallic bond","minutes":5,"book_ref":"Background for Ch.1 General properties, point 3b, p.13 (the strong metallic bond)","subtitle":"Positive ions in a sea of electrons","objectives":["Describe the metallic bond: positive ions held together by free valence electrons.","State that, for neighbours such as Na, Mg and Al, more free valence electrons per atom give a stronger metallic bond and a higher melting point.","Use the bond to explain why metals conduct electricity and can be hammered into shape."],"concept_ids":["bond.metallic-bond"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. The number of bonding electrons matters. Let's see the bond."},{"id":"b","feedback":"Sodium is 23 and magnesium 24.3: barely different, so mass cannot explain a gap of about 550 °C."},{"id":"c","feedback":"Sharing pairs is the covalent bond between non-metals; magnesium atoms are held together by the metallic bond."}],"explanation":"Each magnesium atom releases 2 valence electrons into the sea, while each sodium atom releases 1. More free electrons hold the positive ions more strongly, so the metallic bond of magnesium is stronger and it melts at a higher temperature."}},"s3":{"c":{"body":"For neighbours such as Na, Mg and Al: more free electrons per atom → a stronger metallic bond → higher melting and boiling points."}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"A metal atom easily releases the electrons far from the nucleus, not the ones close to it."},{"id":"m2","feedback":"Shared pairs belong to the covalent bond. In a metal, each atom releases electrons into the sea instead of sharing pairs."}],"explanation":"Each metal atom releases its valence (outer) electrons into the sea."},"q":{"options":[{"id":"a","feedback":"Right. More electrons in the sea hold the positive ions more strongly."},{"id":"b","feedback":"Potassium is 39 and calcium 40: one unit of mass cannot explain a gap of about 780 °C."},{"id":"c","feedback":"Sharing pairs is the covalent bond; calcium atoms are held together by the metallic bond."}],"explanation":"Calcium releases 2 free electrons per atom and potassium 1, so the metallic bond of calcium is stronger and its melting point is higher. Their masses (40 and 39) are almost the same, and metal atoms do not share electron pairs."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. عدد الـ bonding electrons ليه دور. يلا نشوف الـ bond."},{"id":"b","feedback":"الـ sodium كتلته 23، والـ magnesium 24.3: فرق يدوب يتشاف، فالكتلة متقدرش تفسّر فرق حوالي 550 °C."},{"id":"c","feedback":"المشاركة في أزواج دي الـ covalent bond اللي بين الـ non-metals؛ إنما ذرات الـ magnesium بيمسكها الـ metallic bond."}],"explanation":"كل ذرة magnesium بتحرّر 2 valence electrons في البحر، وكل ذرة sodium بتحرّر 1. والـ free electrons الأكتر بتمسك الـ positive ions بقوة أكبر، فالـ metallic bond بتاع الـ magnesium أقوى وبينصهر عند درجة حرارة أعلى."}},"s3":{"c":{"body":"للعناصر الجيران زي الـ Na والـ Mg والـ Al: free electrons أكتر لكل atom → metallic bond أقوى → melting و boiling points أعلى."}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"الـ metal atom بيحرّر بسهولة الـ electrons البعيدة عن الـ nucleus، مش اللي قريبة منها."},{"id":"m2","feedback":"الأزواج المشتركة دي بتاعة الـ covalent bond، إنما في الـ metal كل atom بيحرّر electrons بتاعته في البحر."}],"explanation":"كل metal atom بيحرّر الـ valence (outer) electrons بتاعته في بحر الـ electrons."},"q":{"options":[{"id":"a","feedback":"صح. electrons أكتر في البحر بتمسك الـ positive ions بقوة أكبر."},{"id":"b","feedback":"الـ potassium كتلته 39 والـ calcium 40: وحدة كتلة واحدة متقدرش تفسّر فرق حوالي 780 °C."},{"id":"c","feedback":"المشاركة في أزواج دي الـ covalent bond؛ إنما ذرات الـ calcium بيمسكها الـ metallic bond."}],"explanation":"الـ calcium بيحرّر 2 free electrons لكل ذرة والـ potassium بيحرّر 1، فالـ metallic bond بتاع الـ calcium أقوى والـ melting point بتاعه أعلى. كتلتهم (40 و 39) تقريبًا واحدة، والـ metal atoms مش بتشارك في أزواج electrons."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":3,"is_basics":true,"lesson_no":3,"lesson_count":9,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":377.2,"end_s":443.7,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-bond.metallic-bond","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Metallic bond","duration_s":42.56,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.high-melting-points","kind":"lesson","version":2,"catalog_version":3,"ord":257,"primary_concept_id":"te.high-melting-points","concepts":[{"concept_id":"te.high-melting-points","role":"primary"}],"title":"High melting and boiling points","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Its atoms are heavier","correct":false},{"id":"b","text":"More of its electrons join the metallic bond","correct":true},{"id":"c","text":"Only its 4s electrons bond, just like calcium's","correct":false}],"question":"Predict: what makes titanium's metallic bond so much stronger?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Calcium melts at 842 °C. 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A strong metallic bond.","max_width":340},"visible":{"eq":1,"$state":"/on"},"children":[]},"s0":{"type":"Stat","props":{"tone":"neutral","label":"bonding electrons per Ti atom","value":"2"},"visible":{"eq":0,"$state":"/on"},"children":[]},"s1":{"type":"Stat","props":{"tone":"warning","label":"bonding electrons per Ti atom","value":"4"},"visible":{"eq":1,"$state":"/on"},"children":[]},"sl":{"type":"Slider","props":{"max":1,"min":0,"step":1,"label":"3d electrons in the bond (0 = off, 1 = on)","value":{"$bindState":"/on"}},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["t","sl","d0","d1","s0","s1"]}}},"title":"Switch on the 3d electrons"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Cr","52","1890"],["Cu","63.5","1083"]],"caption":"From the book's table, p.12 (for illustration only)","headers":["Element","Atomic mass","Melting point (°C)"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tb","m"]}}},"title":"Not about heavy atoms"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Scandium's 3d electron joins its 4s electrons in the metallic bond, so the bond is stronger","correct":true},{"id":"b","text":"Agree: heavier atoms always melt higher","correct":false},{"id":"c","text":"Scandium has more 4s electrons than calcium","correct":false}],"question":"A student says: \"Scandium (45) melts higher than calcium (40) because scandium is heavier.\" Which reply fits the book?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"In the transition metals, only the 4s electrons take part in the metallic bond."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"A student's claim"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"Transition elements have high melting points due to the strong ___ bond, formed by sharing both 4s and ___ electrons.","answers":[["metallic"],["3d"]],"mistakes":[{"id":"m1","blank":0,"answer":"ionic"},{"id":"m2","blank":0,"answer":"covalent"},{"id":"m3","blank":1,"answer":"4p"},{"id":"m4","blank":1,"answer":"4s"}]},"children":[]},"h":{"type":"HintLadder","props":{},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","h"]}}},"title":"Write the reason"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["The first transition elements have high melting and boiling points.","Reason: a strong metallic bond, formed by sharing both 4s and 3d electrons.","Potassium and calcium have only 4s electrons to bond, so they melt much lower.","Heavy atoms are not the reason: Cu is heavier than Cr but melts lower."]},"children":[]},"ans":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Titanium vs calcium"}},"children":["ans_tb","ans_t"]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","ans"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why titanium melts so much higher than calcium?"},"children":[]},"ans_t":{"type":"Text","props":{"content":"Calcium has only its two 4s electrons for the metallic bond. In titanium both the 4s and the 3d electrons share in it, so its metallic bond is stronger and more heat is needed to melt it."},"children":[]},"ans_tb":{"type":"DataTable","props":{"rows":[["Ca","2 (4s only)","842"],["Ti","4 (4s and 3d)","1680"]],"headers":["Element","Electrons in the metallic bond","Melting point (°C)"],"highlight":[{"col":1,"row":1}]},"children":[]}}},"title":"Summary"}],"title":"High melting and boiling points","minutes":8,"book_ref":"Ch.1 The general properties of the first transition elements, point 3b + data table, pp.12-13","subtitle":"Both 4s and 3d electrons join the bond","objectives":["Read the melting and boiling point columns of the book's table (for illustration only).","Explain the high values: a strong metallic bond formed by sharing both 4s and 3d electrons.","Contrast with potassium and calcium, where only 4s electrons take part, and reject the 'heavy atoms' idea."],"concept_ids":["te.high-melting-points"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Titanium is 47.9 and calcium 40: that small difference in mass is not what makes the bond so much stronger. We'll test this idea."},{"id":"b","feedback":"Good thinking. The book names which electrons. Let's find them."},{"id":"c","feedback":"Calcium also has $4s^2$, so if only 4s bonded in both, titanium would not melt so much higher."}],"explanation":"More of titanium's electrons join the metallic bond: the book says both the 4s and the 3d electrons share in it. Calcium has no 3d electrons, so its bond uses its 4s electrons and is weaker."}},"s5":{"m":{"statement":"Transition elements melt high because their atoms are heavy.","correction":"Copper is heavier than chromium, yet it melts about 800 °C lower. The strength of the metallic bond decides it, not the mass."}},"s6":{"q":{"options":[{"id":"a","feedback":"Right. Calcium can only use 4s electrons; scandium uses 4s and 3d."},{"id":"b","feedback":"The heavier atom does not always melt higher: copper is heavier than chromium but melts lower."},{"id":"c","feedback":"Ca is [Ar] $4s^2$ and Sc is [Ar] $4s^2\\ 3d^1$, so both have two 4s electrons."}],"explanation":"The reply that fits the book: scandium's 3d electron joins its 4s electrons in the metallic bond, so its bond is stronger than calcium's, which uses 4s electrons. Being heavier is not the reason."},"tf":{"explanation":"Book point 3b: the strong metallic bond forms by sharing both 4s and 3d electrons.","feedback_true":"If only 4s electrons bonded, titanium would be like calcium; the book names the 3d electrons too.","feedback_false":"Right to reject it. Both 4s and 3d electrons share in forming the metallic bond."}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"An ionic bond joins a metal to a non-metal, but here metal atoms bond to each other."},{"id":"m2","feedback":"Metal atoms do not share fixed pairs, as in a covalent bond; they release electrons into a sea."},{"id":"m3","feedback":"4p holds no electrons from Sc to Cu, so it cannot share in the bond."},{"id":"m4","feedback":"4s is already in the sentence; the blank needs the other sublevel that fills from Sc to Cu."}],"explanation":"Book point 3b: the strong metallic bond is formed by sharing both 4s and 3d electrons."},"h":{"hints":["The bond holds metal atoms together.","Write titanium's configuration: [Ar] … Which sublevel appears after 4s?"]}},"s8":{"exam":{"body":"Due to the **strong metallic bond**, formed by the **sharing of both 4s and 3d electrons**.","title":"Give reasons: transition elements have high melting and boiling points"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ atomic mass بتاعة الـ titanium 47.9 وبتاعة الـ calcium 40، والفرق ده صغير قصاد الفرق الكبير في قوة الـ bond. هنختبر الفكرة دي."},{"id":"b","feedback":"تفكير حلو. الكتاب بيحدد أنهي electrons بالظبط. يلا ندوّر عليهم."},{"id":"c","feedback":"الـ calcium برضه عنده $4s^2$. لو الـ 4s لوحده هو اللي بيعمل bond في الاتنين، ماكانش الـ titanium هينصهر عند درجة أعلى بكتير كده."}],"explanation":"الـ titanium عنده electrons أكتر بتشارك في الـ metallic bond: الكتاب بيقول إن الـ 4s والـ 3d electrons الاتنين بيشاركوا فيه. الـ calcium مفيهوش 3d electrons، فالـ bond بتاعه بيعتمد على الـ 4s electrons وبيبقى أضعف."}},"s5":{"m":{"statement":"الـ transition elements الـ melting point بتاعها عالي عشان ذراتها تقيلة.","correction":"الـ copper أتقل من الـ chromium، ومع ذلك بينصهر عند درجة أقل بحوالي 800 °C. اللي بيحدد هو قوة الـ metallic bond، مش الكتلة."}},"s6":{"q":{"options":[{"id":"a","feedback":"صح. الـ calcium مايقدرش يستخدم غير الـ 4s electrons، إنما الـ scandium بيستخدم الـ 4s والـ 3d."},{"id":"b","feedback":"الـ copper أتقل من الـ chromium، لكنه بينصهر عند درجة أقل، فالكتلة الأكبر مش هي اللي بتحدد الـ melting point."},{"id":"c","feedback":"الـ Ca هو [Ar] $4s^2$ والـ Sc هو [Ar] $4s^2\\ 3d^1$: عدد الـ 4s electrons واحد في الاتنين."}],"explanation":"الرد اللي ماشي مع الكتاب: الـ 3d electron بتاع الـ scandium بيشارك مع الـ 4s electrons في الـ metallic bond، فالـ bond بتاعه بيبقى أقوى من بتاع الـ calcium اللي بيستخدم الـ 4s electrons. إنه أتقل مش هو السبب."},"tf":{"explanation":"نقطة 3b في الكتاب: الـ metallic bond القوي بيتكوّن من مشاركة الـ 4s والـ 3d electrons الاتنين.","feedback_true":"لو الـ 4s electrons لوحدها هي اللي بتعمل bond، كان الـ titanium هيبقى زي الـ calcium. الكتاب بيقول إن الـ 3d electrons كمان بتشارك في الـ metallic bond.","feedback_false":"صح إنك رفضتها. الـ 4s والـ 3d electrons الاتنين بيشاركوا في تكوين الـ metallic bond."}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"الـ ionic bond بيربط metal بـ non-metal، وهنا الكلام عن ذرات metal مربوطة ببعضها."},{"id":"m2","feedback":"الـ covalent bond فيه مشاركة بأزواج electrons ثابتة، لكن ذرات الـ metal بتحرّر electrons في بحر."},{"id":"m3","feedback":"الـ 4p مابيبدأش يتملي غير بعد ما الـ 3d يتملي، فمش هو اللي فيه الـ electrons الخارجية من الـ Sc للـ Cu."},{"id":"m4","feedback":"الـ 4s موجود في الجملة خلاص، والفراغ مكانه الـ sublevel التاني اللي بيتملي من الـ Sc للـ Cu."}],"explanation":"نقطة 3b في الكتاب: الـ metallic bond القوي بيتكوّن من مشاركة الـ 4s والـ 3d electrons الاتنين."},"h":{"hints":["الـ bond ده هو اللي بيمسك ذرات الـ metal في بعض.","اكتب الـ configuration بتاع الـ titanium: [Ar] … أنهي sublevel بييجي بعد الـ 4s؟"]}},"s8":{"exam":{"body":"بسبب الـ **metallic bond القوية**، اللي بتتكوّن من **مشاركة الـ 4s والـ 3d electrons مع بعض**.","title":"علّل: الـ transition elements ليها melting and boiling points عالية"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":4,"lesson_no":8,"lesson_count":9,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":307.3,"end_s":443.7,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.high-melting-points","kind":"short","chapter_id":"chem-s3-en.ch1","title":"High melting and boiling points","duration_s":45.72,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.table","section_title":"Data table (atomic mass, radius, density, melting and boiling points)","section_path":["Transition Elements","The general properties of the first transition elements","Data table (atomic mass, radius, density, melting and boiling points)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"5","relation":"based_on"}]},{"id":"chem-s3-en.lesson-phys.density","kind":"lesson","version":3,"catalog_version":3,"ord":259,"primary_concept_id":"phys.density","concepts":[{"concept_id":"phys.density","role":"primary"}],"title":"Density","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"More mass is packed into the same volume","correct":true},{"id":"b","text":"It takes up more space","correct":false},{"id":"c","text":"Gravity pulls only on that ball","correct":false}],"question":"Predict: what is different about the heavier ball?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"You pick up two balls of exactly the same size. One feels much heavier."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Same size, different feel"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Example: an aluminum block has mass 27 g and volume 10 cm³. Its density is 27 ÷ 10 = 2.7 g/cm³."},"children":[]},"fm":{"type":"Formula","props":{"latex":"\\text{density} = \\dfrac{\\text{mass}}{\\text{volume}}","caption":"mass in g, volume in cm³, density in g/cm³"},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Density","definition":"The mass of a unit volume of a substance."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["kt","fm","t"]}}},"title":"Mass per unit volume"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"m":30,"v":10},"elements":{"c":{"type":"Callout","props":{"variant":"tip"},"children":[]},"t":{"type":"Text","props":{"content":"Keep the volume at 10 cm³ and raise the mass. Then try changing the volume."},"children":[]},"sm":{"type":"Slider","props":{"max":100,"min":10,"step":5,"unit":"g","label":"mass","value":{"$bindState":"/m"}},"children":[]},"st":{"type":"Stat","props":{"tone":"brand","unit":"g/cm³","label":"density","value":{"args":{"m":{"$state":"/m"},"v":{"$state":"/v"},"expr":"m / v","digits":2},"$computed":"calc"}},"children":[]},"sv":{"type":"Slider","props":{"max":20,"min":5,"step":1,"unit":"cm³","label":"volume","value":{"$bindState":"/v"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sm","sv","st","c"]}}},"title":"Pack in more mass"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"A 5 cm³ piece of metal has mass 39.5 g. Its density is ___ g/cm³.","answers":[["7.9","7.90"]],"mistakes":[{"id":"m1","blank":0,"answer":"197.5"},{"id":"m2","blank":0,"answer":"0.13"},{"id":"m3","blank":0,"answer":"0.127"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"B","correct":true},{"id":"b","text":"A","correct":false},{"id":"c","text":"Equal: same number of marbles","correct":false}],"question":"Box A and box B are the same size. Each holds 100 marbles of the same size, but B's marbles are heavier. Which box has the greater density?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","q"]}}},"title":"Your turn"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Density is the mass of a unit volume: density = mass ÷ volume, in g/cm³.","Same volume, more mass → higher density.","Next in Chapter 1: why the density of transition metals rises from Sc to Cu."]},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["aluminum block (step 2)","27 g","10 cm³","2.7 g/cm³"],["metal piece (step 4)","39.5 g","5 cm³","7.9 g/cm³"]],"caption":"Density: the mass of a unit volume, in g/cm³","headers":["Sample","Mass","Volume","Density = mass ÷ volume"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tab","b","self"]},"self":{"type":"Text","props":{"content":"Can you explain why two balls of the same size can have different densities?"},"children":[]}}},"title":"Summary"}],"title":"Density","minutes":5,"book_ref":"Background for Ch.1 General properties, point 3c, p.13 (high density)","subtitle":"How much mass fits in each cm³","objectives":["Define density as mass per unit volume: density = mass ÷ volume, in g/cm³.","Calculate a density from a mass and a volume.","Explain that more mass in the same volume means a higher density."],"concept_ids":["phys.density"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. That idea has a name: density."},{"id":"b","feedback":"They are the same size, so their volumes are equal; the difference is the mass packed into that volume."},{"id":"c","feedback":"Gravity pulls on both balls; one feels heavier because it holds more mass in the same space."}],"explanation":"The two balls have the same size, so the same volume, and gravity pulls on both. The heavier one has more mass packed into the same volume: it has a higher density."}},"s3":{"c":{"body":"Same volume, more mass → higher density."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"You multiplied. Density is mass per unit volume, so mass is divided by volume."},{"id":"m2","feedback":"You divided volume by mass. Mass goes on top: density = mass ÷ volume."},{"id":"m3","feedback":"You divided volume by mass. Mass goes on top: density = mass ÷ volume."}],"explanation":"density = mass ÷ volume = 39.5 ÷ 5 = 7.9 g/cm³."},"q":{"options":[{"id":"a","feedback":"Right. Same volume, more mass, so higher density."},{"id":"b","feedback":"Both boxes have the same volume, but B's heavier marbles give it more mass, so B is denser."},{"id":"c","feedback":"Density uses mass, not the number of pieces: B's marbles are heavier, so B has more mass in the same volume."}],"explanation":"Density = mass ÷ volume. The boxes have the same volume and the same number of marbles, but B's marbles are heavier, so B has more mass in the same volume and the greater density."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. الفكرة دي ليها اسم: density."},{"id":"b","feedback":"الكورتين في نفس الحجم، يعني الـ volume بتاعهم واحد؛ الفرق في الـ mass المحشورة في الـ volume ده."},{"id":"c","feedback":"الجاذبية بتشد الكورتين الاتنين؛ واحدة فيهم أتقل عشان شايلة mass أكتر في نفس المساحة."}],"explanation":"الكورتين في نفس الحجم، يعني نفس الـ volume، والجاذبية بتشد الاتنين. الأتقل فيهم محشور فيه mass أكتر في نفس الـ volume: يعني الـ density بتاعته أعلى."}},"s3":{"c":{"body":"نفس الـ volume و mass أكتر، يبقى الـ density أعلى."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"إنت ضربت، لكن الـ density هي الـ mass لكل وحدة volume، يعني قسمة مش ضرب."},{"id":"m2","feedback":"إنت قسمت الـ volume على الـ mass، والـ density بالعكس: الـ mass هي اللي فوق."},{"id":"m3","feedback":"إنت قسمت الـ volume على الـ mass، والـ density بالعكس: الـ mass هي اللي فوق."}],"explanation":"الـ density = mass ÷ volume = 39.5 ÷ 5 = 7.9 g/cm³."},"q":{"options":[{"id":"a","feedback":"صح. نفس الـ volume، و mass أكتر، يبقى density أعلى."},{"id":"b","feedback":"الصندوقين ليهم نفس الـ volume، لكن البلي التقيل بتاع B بيدّيه mass أكتر، فـ B الـ density بتاعه أعلى."},{"id":"c","feedback":"الـ density بتعتمد على الـ mass، مش على عدد الحتت: البلي بتاع B أتقل، فـ B فيه mass أكتر في نفس الـ volume."}],"explanation":"الـ density = mass ÷ volume. الصندوقين ليهم نفس الـ volume ونفس عدد البلي، لكن البلي بتاع B أتقل، فـ B فيه mass أكتر في نفس الـ volume، والـ density بتاعه أكبر."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":4,"is_basics":true,"lesson_no":4,"lesson_count":9,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":460.3,"end_s":529.2,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-phys.density","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Density","duration_s":43.29,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"beyond"}]},{"id":"chem-s3-en.lesson-te.density-trend","kind":"lesson","version":4,"catalog_version":3,"ord":261,"primary_concept_id":"te.density-trend","concepts":[{"concept_id":"te.density-trend","role":"primary"}],"title":"Density increases with atomic number","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Copper atoms are smaller, so more fit in","correct":false},{"id":"b","text":"Copper atoms are heavier, but about the same size","correct":true},{"id":"c","text":"Copper's cube has more empty space","correct":false}],"question":"Predict: why is the copper cube heavier?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Chromium and copper atoms have the same radius (1.17 in the book's table). Yet a 1 cm³ cube of chromium has mass 7.19 g, and the same cube of copper: 8.92 g."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Heavier cubes"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Book point 3c: most of them have **high density**, which **increases with the atomic number**."},"children":[]},"ch":{"type":"Chart","props":{"kind":"line","unit":"g/cm³","series":[{"name":"Density","points":[{"x":"Sc","y":3.1},{"x":"Ti","y":4.42},{"x":"V","y":6.07},{"x":"Cr","y":7.19},{"x":"Mn","y":7.21},{"x":"Fe","y":7.87},{"x":"Co","y":8.7},{"x":"Ni","y":8.9},{"x":"Cu","y":8.92}]}],"caption":"Density from Sc to Cu (book's table, p.12, for illustration only). Aluminum, for comparison: 2.7 g/cm³.","x_label":"Element (Sc → Cu)","y_label":"Density"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["ch","t"]}}},"title":"The density column"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"From Cr to Cu, the atomic radius hardly changes, but the atomic mass rises from 52 to 63.5."},"children":[]},"t2":{"type":"Text","props":{"content":"More mass in about the same volume: the density **increases**."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Cr","52","1.17","7.19"],["Mn","54.9","1.17","7.21"],["Fe","55.9","1.16","7.87"],["Co","58.9","1.16","8.70"],["Ni","58.7","1.15","8.90"],["Cu","63.5","1.17","8.92"]],"caption":"Cr to Cu, from the book's table, p.12 (for illustration only)","headers":["Element","Atomic mass","Atomic radius","Density (g/cm³)"],"highlight":[{"col":1,"row":0},{"col":1,"row":5},{"col":2,"row":0},{"col":2,"row":5}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tb","t","t2"]}}},"title":"Mass up, size steady"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"k":1},"elements":{"t":{"type":"Text","props":{"content":"Step from Cr to Cu. 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fill-opacity=\"0.33\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"215\" cy=\"33\" r=\"25.7\" fill=\"#fbbf24\" fill-opacity=\"0.33\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"85\" cy=\"85\" r=\"25.7\" fill=\"#fbbf24\" fill-opacity=\"0.33\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"150\" cy=\"85\" r=\"25.7\" fill=\"#fbbf24\" fill-opacity=\"0.33\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"215\" cy=\"85\" r=\"25.7\" fill=\"#fbbf24\" fill-opacity=\"0.33\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"85\" cy=\"137\" r=\"25.7\" fill=\"#fbbf24\" fill-opacity=\"0.33\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"150\" cy=\"137\" r=\"25.7\" fill=\"#fbbf24\" fill-opacity=\"0.33\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"215\" cy=\"137\" r=\"25.7\" fill=\"#fbbf24\" fill-opacity=\"0.33\" stroke=\"#fbbf24\" stroke-width=\"2\"/></svg>","caption":"$\\ce{Mn}$: same box, atoms of radius 1.17","max_width":300},"visible":{"eq":2,"$state":"/k"},"children":[]},"d3":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 300 170\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"55\" y=\"5\" width=\"190\" height=\"160\" rx=\"6\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"2\" stroke-dasharray=\"6 4\"/><circle cx=\"85\" cy=\"33\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.39\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"150\" cy=\"33\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.39\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"215\" cy=\"33\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.39\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"85\" cy=\"85\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.39\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"150\" cy=\"85\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.39\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"215\" cy=\"85\" r=\"25.5\" fill=\"#fbbf24\" 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fill-opacity=\"0.57\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"215\" cy=\"33\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.57\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"85\" cy=\"85\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.57\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"150\" cy=\"85\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.57\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"215\" cy=\"85\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.57\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"85\" cy=\"137\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.57\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"150\" cy=\"137\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.57\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"215\" cy=\"137\" r=\"25.5\" fill=\"#fbbf24\" fill-opacity=\"0.57\" stroke=\"#fbbf24\" stroke-width=\"2\"/></svg>","caption":"$\\ce{Co}$: same box, atoms of radius 1.16","max_width":300},"visible":{"eq":4,"$state":"/k"},"children":[]},"d5":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 300 170\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"55\" y=\"5\" width=\"190\" height=\"160\" rx=\"6\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"2\" stroke-dasharray=\"6 4\"/><circle cx=\"85\" cy=\"33\" r=\"25.3\" fill=\"#fbbf24\" fill-opacity=\"0.56\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"150\" cy=\"33\" r=\"25.3\" fill=\"#fbbf24\" fill-opacity=\"0.56\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"215\" cy=\"33\" r=\"25.3\" fill=\"#fbbf24\" fill-opacity=\"0.56\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"85\" cy=\"85\" r=\"25.3\" fill=\"#fbbf24\" fill-opacity=\"0.56\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"150\" cy=\"85\" r=\"25.3\" fill=\"#fbbf24\" fill-opacity=\"0.56\" stroke=\"#fbbf24\" stroke-width=\"2\"/><circle cx=\"215\" cy=\"85\" r=\"25.3\" fill=\"#fbbf24\" 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box, atoms of radius 1.17","max_width":300},"visible":{"eq":6,"$state":"/k"},"children":[]},"m1":{"type":"Stat","props":{"tone":"warning","label":"atomic mass","value":"52"},"children":[]},"m2":{"type":"Stat","props":{"tone":"warning","label":"atomic mass","value":"54.9"},"children":[]},"m3":{"type":"Stat","props":{"tone":"warning","label":"atomic mass","value":"55.9"},"children":[]},"m4":{"type":"Stat","props":{"tone":"warning","label":"atomic mass","value":"58.9"},"children":[]},"m5":{"type":"Stat","props":{"tone":"warning","label":"atomic mass","value":"58.7"},"children":[]},"m6":{"type":"Stat","props":{"tone":"warning","label":"atomic 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g/cm³"},"children":[]},"x2":{"type":"Stat","props":{"tone":"brand","label":"density","value":"7.21 g/cm³"},"children":[]},"x3":{"type":"Stat","props":{"tone":"brand","label":"density","value":"7.87 g/cm³"},"children":[]},"x4":{"type":"Stat","props":{"tone":"brand","label":"density","value":"8.70 g/cm³"},"children":[]},"x5":{"type":"Stat","props":{"tone":"brand","label":"density","value":"8.90 g/cm³"},"children":[]},"x6":{"type":"Stat","props":{"tone":"brand","label":"density","value":"8.92 g/cm³"},"children":[]},"root":{"type":"Stack","props":{"gap":"md"},"children":["t","sl","d1","r1","d2","r2","d3","r3","d4","r4","d5","r5","d6","r6"]}}},"title":"Same box, heavier atoms"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Remember the radius lesson: two opposite factors keep the size relatively constant."},"children":[]},"rc":{"type":"Chart","props":{"kind":"bar","title":"Atomic radius from Cr to Cu","series":[{"name":"Atomic radius","points":[{"x":"Cr","y":1.17},{"x":"Mn","y":1.17},{"x":"Fe","y":1.16},{"x":"Co","y":1.16},{"x":"Ni","y":1.15},{"x":"Cu","y":1.17}]}],"caption":"Book's table, p.12 (for illustration only): 1.17 at both ends, while the density rises from 7.19 to 8.92 g/cm³.","x_label":"Element (Cr → Cu)","y_label":"Atomic radius","highlight":["Cr","Cu"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["rc","t"]}}},"title":"Smaller atoms?"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Y","correct":true},{"id":"b","text":"X","correct":false},{"id":"c","text":"Equal: the atoms are the same size","correct":false}],"question":"Metals X and Y have atoms of the same radius, packed the same way. Y's atomic mass is 20% larger. Which is denser?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"From Cr to Cu, the density rises mainly because the atoms get much smaller."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"New metals"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"o":{"type":"Ordering","props":{"items":[{"id":"a","text":"The atomic number increases across the series"},{"id":"b","text":"So the atomic mass increases"},{"id":"c","text":"But the atomic size stays relatively constant, so the volume hardly changes"},{"id":"d","text":"So more mass is packed into about the same volume, and the density increases"}],"prompt":"Give reasons: the density increases with atomic number. Put the answer in order."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o"]}}},"title":"Build the exam answer"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Most first-series transition elements have high density.","Density increases with atomic number: Sc 3.10 → Cu 8.92 g/cm³ (book's table).","Reason: the atomic mass increases while the atomic size is relatively constant."]},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a"},{"to":"c","from":"b","label":"but"},{"to":"d","from":"c"},{"to":"e","from":"d"}],"nodes":[{"id":"a","label":"Atomic number increases"},{"id":"b","label":"Atomic mass increases"},{"id":"c","label":"Atomic size relatively constant"},{"id":"d","label":"More mass in about the same volume"},{"id":"e","label":"Density increases"}],"layout":"vertical","caption":"Book point 3c, p.13"},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","fl","exam","self"]},"self":{"type":"Text","props":{"content":"Back to the hook: why is a copper cube heavier than a chromium cube of the same size, when their atoms have the same radius?"},"children":[]}}},"title":"Summary"}],"title":"Density increases with atomic number","minutes":7,"book_ref":"Ch.1 The general properties of the first transition elements, point 3c + data table, pp.12-13","subtitle":"More mass in about the same space","objectives":["Read the density column of the book's table (for illustration only).","State that most of them have high density, which increases with atomic number.","Explain why: the atomic mass increases while the atomic size stays relatively constant."],"concept_ids":["te.density-trend"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"The atoms did not get smaller from Cr to Cu: both have radius 1.17 in the book's table."},{"id":"b","feedback":"Good thinking. That is the book's reason. Let's test it on the table."},{"id":"c","feedback":"More empty space would mean less mass per cm³, which would make the copper cube lighter, not heavier."}],"explanation":"Chromium and copper atoms have the same radius (1.17), but copper's atomic mass is larger (63.5 against 52). More mass in about the same volume gives the higher density: 8.92 g/cm³ against 7.19 g/cm³."}},"s6":{"q":{"options":[{"id":"a","feedback":"Right. Same volume per atom, more mass per atom, so higher density."},{"id":"b","feedback":"X has the smaller atomic mass: same-size atoms take the same space, so X puts less mass into it."},{"id":"c","feedback":"Equal size fixes the volume, not the mass: the atomic masses differ by 20%, so the mass in that volume differs too."}],"explanation":"Same radius and same packing mean the same volume per atom. Y's atomic mass is 20% larger, so Y packs more mass into the same volume and is denser."},"tf":{"explanation":"From Cr to Cu the atomic radius hardly changes (1.17 at both ends), yet the density still rises, so shrinking atoms cannot be the reason. Book point 3c: the atomic size is relatively constant while the atomic mass increases.","feedback_true":"The atoms did not shrink much: the radius is 1.17 at both Cr and Cu. What changed is the atomic mass, which rises from 52 to 63.5.","feedback_false":"Right to reject it. The size is relatively constant; the atomic mass increases."}},"s7":{"o":{"items":[{"id":"a","feedback":"The answer starts from the cause given in the question: the atomic number increases."},{"id":"b","feedback":"More protons and neutrons in each atom raise the atomic mass, so this comes right after the atomic number."},{"id":"c","feedback":"'But' contrasts with the rising mass, so it comes after the atomic mass increases."},{"id":"d","feedback":"This is the final result, not a cause, so it comes last."}],"explanation":"The atomic number increases, so the atomic mass increases. But the atomic size stays relatively constant, so more mass is packed into about the same volume and the density increases."}},"s8":{"exam":{"body":"Because the **atomic size is relatively constant** with **increasing atomic mass**.","title":"Give reasons: the density increases with atomic number"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الذرات ماصغرتش من الـ Cr للـ Cu: الاتنين الـ radius بتاعهم 1.17 في جدول الكتاب."},{"id":"b","feedback":"تفكير حلو. ده سبب الكتاب. يلا نجرّبه على الجدول."},{"id":"c","feedback":"فراغ أكتر معناه mass أقل في كل cm³، وده كان هيخلّي مكعب الـ copper أخف، مش أتقل."}],"explanation":"ذرات الـ chromium والـ copper ليهم نفس الـ radius (1.17)، لكن الـ atomic mass بتاع الـ copper أكبر (63.5 قصاد 52). mass أكتر في نفس الـ volume تقريبًا بيدّي density أعلى: 8.92 g/cm³ قصاد 7.19 g/cm³."}},"s6":{"q":{"options":[{"id":"a","feedback":"صح. نفس الحجم لكل ذرة، و mass أكتر لكل ذرة، يبقى الـ density أعلى."},{"id":"b","feedback":"الـ X الـ atomic mass بتاعه أصغر: الذرات اللي ليها نفس الحجم بتاخد نفس المساحة، فالـ X بيحط فيها mass أقل."},{"id":"c","feedback":"الحجم المتساوي بيحدد الـ volume، مش الـ mass: الـ atomic masses بينهم فرق 20%، فالـ mass اللي جوه الـ volume ده مختلف هو كمان."}],"explanation":"نفس الـ radius ونفس الترتيب يعني نفس الـ volume لكل ذرة. الـ atomic mass بتاع الـ Y أكبر بـ 20%، فالـ Y بيحط mass أكتر في نفس الـ volume، فالـ density بتاعته أعلى."},"tf":{"explanation":"من الـ Cr للـ Cu الـ atomic radius تقريبًا مابيتغيّرش (1.17 في الطرفين)، ومع ذلك الـ density بتزيد، يبقى صِغر الذرات مش هو السبب. نقطة 3c في الكتاب: الـ atomic size ثابت نسبيًا (relatively constant)، والـ atomic mass بيزيد.","feedback_true":"الذرات ماصغرتش كتير: الـ radius 1.17 عند الـ Cr وعند الـ Cu. اللي اتغيّر هو الـ atomic mass، اللي بيزيد من 52 لـ 63.5.","feedback_false":"صح إنك رفضتها. الـ atomic size ثابت نسبيًا، والـ atomic mass هو اللي بيزيد."}},"s7":{"o":{"items":[{"id":"a","feedback":"الإجابة بتبدأ من السبب اللي في السؤال: الـ atomic number بيزيد."},{"id":"b","feedback":"protons و neutrons أكتر في كل ذرة بيزوّدوا الـ atomic mass، فده بييجي بعد الـ atomic number على طول."},{"id":"c","feedback":"كلمة 'But' بتقارن بالـ mass اللي بيزيد، فبتيجي بعد زيادة الـ atomic mass."},{"id":"d","feedback":"دي النتيجة النهائية، مش سبب، فبتيجي في الآخر."}],"explanation":"الـ atomic number بيزيد، فالـ atomic mass بيزيد. لكن الـ atomic size بيفضل ثابت نسبيًا (relatively constant)، فـ mass أكتر بيتحط في نفس الـ volume تقريبًا، والـ density بتزيد."}},"s8":{"exam":{"body":"عشان **الـ atomic size ثابت تقريبًا** مع **زيادة الـ atomic mass**.","title":"علّل: الـ density بتزيد مع الـ atomic number"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":5,"lesson_no":9,"lesson_count":9,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-physical-properties","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"General properties: mass, radius and metallic property","duration_s":626.244,"start_s":460.3,"end_s":535.3,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.density-trend","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Density increases with atomic number","duration_s":46.04,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.table","section_title":"Data table (atomic mass, radius, density, melting and boiling points)","section_path":["Transition Elements","The general properties of the first transition elements","Data table (atomic mass, radius, density, melting and boiling points)"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.magnetic-properties","kind":"lesson","version":2,"catalog_version":3,"ord":292,"primary_concept_id":"te.magnetic-properties","concepts":[{"concept_id":"te.magnetic-properties","role":"primary"}],"title":"Paramagnetic and diamagnetic substances","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Iron is a magnet; 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Magnetic moment zero."}},"s5":{"m":{"statement":"A diamagnetic substance is not affected by a magnetic field.","correction":"It is repelled, weakly, because all its electrons are paired. $d^{10}$ is repelled, while $d^8$, with unpaired electrons, is attracted."}},"s6":{"h":{"hints":["Count the boxes that hold only one electron (↑).","Zero unpaired electrons means diamagnetic.","More unpaired electrons means a larger magnetic moment."]}},"s7":{"q":{"options":[{"id":"a","feedback":"It has the most d electrons, but in $3d^{10}$ every electron is paired."},{"id":"b","feedback":"Its three 3d electrons are unpaired, but another ion here has more unpaired electrons."},{"id":"c","feedback":"Seven is more than five, but some of those electrons pair up: $3d^7$ has 3 unpaired."},{"id":"d","feedback":"Right. $3d^5$ puts one electron in each box: 5 unpaired, the most here."}],"explanation":"Unpaired: $3d^{10}$ 0, $3d^3$ 3, $3d^7$ 3, $3d^5$ 5. The magnetic moment follows the unpaired electrons, not the total."},"tf":{"explanation":"Paramagnetic: attracted to the external magnetic field due to unpaired electrons.","feedback_true":"That describes a magnet. A paramagnetic substance is attracted to an external magnetic field; it is not a magnet itself.","feedback_false":"Right. It is only attracted to an external magnetic field; it is not a magnet itself."}},"s8":{"c":{"items":[{"id":"v","feedback":"By Hund's rule, 3 electrons in 5 boxes go one per box, so each of the 3 is unpaired."},{"id":"zn","feedback":"Ten electrons fill five boxes, so every electron is paired."},{"id":"mn","feedback":"Five electrons in five boxes go one in each, so each of the five is unpaired."},{"id":"sc","feedback":"With no d electrons at all, this ion has no unpaired electrons."},{"id":"cu","feedback":"Nine electrons in five boxes cannot all be paired: one stays unpaired."}],"explanation":"Any unpaired electron makes the ion paramagnetic. $3d^0$ and $3d^{10}$ have none: diamagnetic."},"f":{"mistakes":[{"id":"m1","feedback":"Attraction comes from electrons without a partner, and here every spin has an opposite partner."},{"id":"m2","feedback":"Attraction comes from electrons without a partner, and here every spin has an opposite partner."},{"id":"m3","feedback":"The book says the field does act on a diamagnetic substance, so the field is not ignored."},{"id":"m4","feedback":"Electrons without a partner give attraction; a zero moment needs every electron to have an opposite-spin partner."}],"explanation":"Book p.14: a diamagnetic substance repels the external magnetic field, due to the pairing of all its electrons."}},"s9":{"exam":{"body":"Because they have **unpaired electrons** in the d sublevel. Spinning unpaired electrons form a **magnetic field**, so the substance is **paramagnetic**.","title":"Give reasons: most transition elements are attracted to the external magnetic field"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ iron كـ metal ممكن يتمغنط، لكن هنا الـ iron موجود كـ ion جوه compound، والمهم هو ترتيب الـ electrons بتاعة الـ ion ده في الـ orbitals بتاعته."},{"id":"b","feedback":"تفكير حلو. الـ unpaired electrons هما مفتاح الحكاية. الدرس ده هيوريك إزاي هما اللي بيعملوا الشدّ ده."},{"id":"c","feedback":"لكن الـ zinc compound بيتحرك فعلًا: بيتزق لبرّه. يعني الـ field بيأثر عليه، والـ electrons اللي جواه هي اللي بتستجيب."}],"explanation":"الـ $\\ce{Fe^{3+}}$ ($3d^5$) فيه unpaired electrons، فالـ $\\ce{FeCl3}$ بيبقى paramagnetic وبيتجذب للـ magnetic field. أما في الـ $\\ce{Zn^{2+}}$ ($3d^{10}$) فالـ electrons كلها paired، فالـ $\\ce{ZnSO4}$ بيبقى diamagnetic وبيتنافر مع الـ field."}},"s3":{"m":{"statement":"الـ paramagnetic substance يبقى مغناطيس.","correction":"هي بتتجذب طول ما هي جوه external field تحديدًا. شيل المغناطيس، ومش هتجذب أي حاجة لوحدها، على عكس المغناطيس العادي (bar magnet)."}},"s4":{"m":{"statement":"كل ما الـ electrons تزيد، المادة تبقى مغناطيسية أكتر.","correction":"اللي بيفرق هو الـ **unpaired** electrons تحديدًا. الـ $d^5$ فيه 5 unpaired، إنما الـ $d^{10}$، مع إن الـ electrons فيه أكتر، مفيهوش ولا واحد: الـ magnetic moment بصفر."},"c5":{"body":"الـ $d^5$: electron واحد في كل مربع. 5 unpaired: ده أكبر magnetic moment ممكن الـ d sublevel يديه."},"c10":{"body":"الـ $d^{10}$: أكتر عدد d electrons، ومع كده مفيش ولا واحد unpaired. الـ magnetic moment بصفر."}},"s5":{"m":{"statement":"الـ diamagnetic substance مابتتأثرش بالـ magnetic field.","correction":"هي بتتنافر معاه، بشكل ضعيف، عشان كل الـ electrons بتاعتها أزواج. الـ $d^{10}$ بيتنافر، إنما الـ $d^8$، اللي فيه unpaired electrons، بيتجذب."}},"s6":{"h":{"hints":["عدّ المربعات اللي فيها electron واحد لوحده (↑).","صفر unpaired electrons يعني diamagnetic.","كل ما الـ unpaired electrons تزيد، الـ magnetic moment بيكبر."]}},"s7":{"q":{"options":[{"id":"a","feedback":"ده عنده أكبر عدد d electrons فعلًا، لكن الـ $3d^{10}$ كلها paired ومفيهاش ولا unpaired electron."},{"id":"b","feedback":"كل الـ 3d electrons بتوعه unpaired، لكنهم 3 بس، وفيه ion تاني هنا عنده unpaired electrons أكتر."},{"id":"c","feedback":"سبعة أكتر من خمسة، لكن في الـ $3d^7$ اتنين بيعملوا أزواج، فبيفضل 3 unpaired بس."},{"id":"d","feedback":"صح. الـ $3d^5$ بيحط electron واحد في كل مربع: 5 unpaired، وده أكتر عدد هنا."}],"explanation":"عدد الـ unpaired: الـ $3d^{10}$ فيه 0، والـ $3d^3$ فيه 3، والـ $3d^7$ فيه 3، والـ $3d^5$ فيه 5. الـ magnetic moment ماشي ورا عدد الـ unpaired electrons، مش العدد الكلي."},"tf":{"explanation":"الـ paramagnetic: بتتجذب للـ external magnetic field بسبب وجود unpaired electrons.","feedback_true":"ده وصف الـ magnet. الـ paramagnetic substance بتتجذب للـ external magnetic field بس، ومش بتجذب حاجة بنفسها.","feedback_false":"صح. هي بتتجذب للـ external magnetic field تحديدًا؛ هي نفسها مش magnet."}},"s8":{"c":{"items":[{"id":"v","feedback":"حسب الـ Hund's rule، الـ 3 electrons بيتوزعوا على 3 مربعات من الـ 5، وكل واحد فيهم من غير شريك."},{"id":"zn","feedback":"عشرة electrons بيملوا الخمس مربعات، فكل electron ليه شريك ومفيش unpaired."},{"id":"mn","feedback":"خمسة electrons وخمس مربعات، واحد في كل مربع، فمفيش ولا واحد فيهم ليه شريك."},{"id":"sc","feedback":"مفيش d electrons خالص، فمفيش في الـ ion ده أي unpaired electrons."},{"id":"cu","feedback":"تسعة electrons في خمس مربعات مايقدروش يبقوا paired كلهم، فبيفضل واحد unpaired."}],"explanation":"أي unpaired electron بيخلّي الـ ion يبقى paramagnetic. الـ $3d^0$ والـ $3d^{10}$ مفيهمش ولا واحد: يبقوا diamagnetic."},"f":{"mistakes":[{"id":"m1","feedback":"الجذب بييجي من electrons مالهاش شريك، والمادة دي كل electron فيها ليه شريك عكسه."},{"id":"m2","feedback":"الجذب بييجي من electrons مالهاش شريك، والمادة دي كل electron فيها ليه شريك عكسه."},{"id":"m3","feedback":"الكتاب بيقول إن الـ field بيأثر عليها فعلًا، فالعيّنة بتتحرك ومش بتفضل مكانها."},{"id":"m4","feedback":"الـ electrons اللي مالهاش شريك بتدّي جذب، والـ diamagnetic substance الـ moment بتاعها صفر."}],"explanation":"الكتاب ص.14: الـ diamagnetic substance بتتنافر مع الـ external magnetic field، بسبب إن كل الـ electrons بتاعتها paired."}},"s9":{"exam":{"body":"عشان عندها **unpaired electrons** في الـ d sublevel. والـ unpaired electrons وهي بتلف حوالين نفسها بتكوّن **magnetic field**، فالمادة بتبقى **paramagnetic**.","title":"علّل: معظم الـ transition elements بتتجذب للـ external magnetic field"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":1,"lesson_no":5,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-magnetism-catalysis","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Magnetic properties and catalytic activity","duration_s":702.279,"start_s":30.1,"end_s":108.3,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-te.magnetic-properties","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Paramagnetic and diamagnetic substances","duration_s":56.37,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic.ex-a","section_title":"Paramagnetic or diamagnetic","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties","Paramagnetic or diamagnetic"],"exercise":"Exercise","relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"6","relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.magnetic-moment-from-config","kind":"lesson","version":2,"catalog_version":3,"ord":294,"primary_concept_id":"te.magnetic-moment-from-config","concepts":[{"concept_id":"te.magnetic-moment-from-config","role":"primary"}],"title":"Unpaired electrons and magnetic moment","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"They are equal: both contain iron, $3d^6$","correct":false},{"id":"b","text":"$\\ce{FeCl2}$: iron keeps more electrons","correct":false},{"id":"c","text":"$\\ce{FeCl3}$","correct":true}],"question":"Predict: which has the larger magnetic moment?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"$\\ce{FeCl2}$ and $\\ce{FeCl3}$ both contain iron. Are they equally magnetic?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Same metal, two chlorides"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"In a compound the metal is an **ion**. So count the unpaired electrons of the ion, not of the atom."},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a"},{"to":"c","from":"b"},{"to":"d","from":"c"},{"to":"e","from":"d"},{"to":"f","from":"e"}],"nodes":[{"id":"a","label":"Compound"},{"id":"b","label":"Oxidation state of the metal"},{"id":"c","label":"Ion's 3d configuration (4s lost first)"},{"id":"d","label":"3d boxes by Hund's rule"},{"id":"e","label":"Count unpaired electrons"},{"id":"f","label":"Classify and order"}],"layout":"vertical"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fl","t","m"]}}},"title":"Count on the ion"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Book, Q7.9: iron(III) chloride is paramagnetic. Open each step and read its reason."},"children":[]},"r1":{"type":"Reveal","props":{"label":"Step 1: oxidation state"},"children":["r1t"]},"r2":{"type":"Reveal","props":{"label":"Step 2: the ion's configuration"},"children":["r2t"]},"r3":{"type":"Reveal","props":{"label":"Step 3: boxes and count"},"children":["r3b","r3t"]},"r1t":{"type":"Text","props":{"content":"Cl is −1. Three Cl give −3, and the compound is neutral, so Fe is **+3**."},"children":[]},"r2t":{"type":"Text","props":{"content":"Fe is $[\\text{Ar}]\\ 4s^2\\ 3d^6$. It loses the two 4s electrons first, then one 3d: $\\ce{Fe^3+}$ is $[\\text{Ar}]\\ 3d^5$."},"children":[]},"r3b":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"3d","electrons":5}],"caption":"$\\ce{Fe^3+}$: $3d^5$","show_unpaired":true},"children":[]},"r3t":{"type":"Text","props":{"content":"One electron in each box: **5 unpaired**, so $\\ce{FeCl3}$ is **paramagnetic**."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","r1","r2","r3","m"]}}},"title":"Worked: FeCl₃"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["O is −2. Three O give −6, shared by two Cr, so Cr is +3.","Cr is $[\\text{Ar}]\\ 4s^1\\ 3d^5$. It loses 4s¹, then two 3d: $\\ce{Cr^3+}$ is $[\\text{Ar}]\\ 3d^3$."],"ordered":true},"children":[]},"f":{"type":"FillBlank","props":{"text":"$\\ce{Cr^3+}$ has ___ unpaired electrons, so $\\ce{Cr2O3}$ is ___.","answers":[["3","three"],["paramagnetic"]],"mistakes":[{"id":"m1","blank":0,"answer":"0"},{"id":"m2","blank":0,"answer":"5"},{"id":"m3","blank":0,"answer":"1"},{"id":"m4","blank":1,"answer":"diamagnetic"}]},"children":[]},"h":{"type":"HintLadder","props":{},"children":[]},"t":{"type":"Text","props":{"content":"A compound from the book's exercise. Steps 1 and 2 are done. You finish steps 3 and 4."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","b","f","h"]}}},"title":"Your part: Cr₂O₃"},{"id":"s5","kind":"interact","spec":{"root":"root","state":{"ox":2},"elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Vanadium forms $\\ce{VO}$, $\\ce{V2O3}$, $\\ce{VO2}$ and $\\ce{V2O5}$. Move through its oxidation states."},"children":[]},"b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"3d","electrons":3}],"caption":"VO: V²⁺ is [Ar] 3d³","show_unpaired":true},"visible":{"eq":2,"$state":"/ox"},"children":[]},"b3":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"3d","electrons":2}],"caption":"V₂O₃: V³⁺ is [Ar] 3d²","show_unpaired":true},"visible":{"eq":3,"$state":"/ox"},"children":[]},"b4":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"3d","electrons":1}],"caption":"VO₂: V⁴⁺ is [Ar] 3d¹","show_unpaired":true},"visible":{"eq":4,"$state":"/ox"},"children":[]},"b5":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"3d","electrons":0}],"caption":"V₂O₅: V⁵⁺ is [Ar] 3d⁰","show_unpaired":true},"visible":{"eq":5,"$state":"/ox"},"children":[]},"sl":{"type":"Slider","props":{"max":5,"min":2,"step":1,"label":"oxidation state of vanadium","value":{"$bindState":"/ox"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","b2","b3","b4","b5","m"]}}},"title":"One metal, four ions"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"ti","text":"$\\ce{TiCl4}$"},{"id":"cu1","text":"$\\ce{CuCl}$"},{"id":"sc","text":"$\\ce{Sc2O3}$"},{"id":"cu2","text":"$\\ce{CuSO4}$"},{"id":"ni","text":"NiO"}],"answer":{"dia":["ti","cu1","sc"],"para":["cu2","ni"]},"prompt":"Sort the compounds. Find each metal's oxidation state first.","categories":[{"id":"para","label":"Paramagnetic"},{"id":"dia","label":"Diamagnetic"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c"]}}},"title":"Para or dia?"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"o":{"type":"Ordering","props":{"items":[{"id":"ti","text":"$\\ce{TiCl3}$"},{"id":"ni","text":"$\\ce{NiSO4}$"},{"id":"co","text":"$\\ce{CoSO4}$"},{"id":"mn","text":"$\\ce{MnCl2}$"}],"prompt":"Arrange in ascending order of magnetic moment (smallest first)."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o","h"]}}},"title":"Ascending order"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Oxidation state → the ion (4s lost first) → 3d boxes by Hund's rule → count unpaired electrons.","No unpaired electrons ($3d^0$, $3d^{10}$): diamagnetic. Any unpaired: paramagnetic.","More unpaired electrons, larger magnetic moment."]},"children":[]},"ans":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Why the iron atom gives the wrong count"}},"children":["ans_t","ans_c"]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","exam","self","ans"]},"self":{"type":"Text","props":{"content":"Back to the hook: $\\ce{FeCl3}$ (5 unpaired) beats $\\ce{FeCl2}$ (4). Can you explain why the iron atom gives the wrong count?"},"children":[]},"ans_c":{"type":"Columns","props":{"columns":2},"children":["ans_b1","ans_b2"]},"ans_t":{"type":"Text","props":{"content":"In $\\ce{FeCl3}$ iron is the ion $\\ce{Fe^3+}$, not the atom. It has lost the two 4s electrons and one 3d electron, so its 3d is $3d^5$ (5 unpaired), not the atom's $3d^6$ (4 unpaired)."},"children":[]},"ans_b1":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"3d","electrons":6}],"caption":"Fe atom: $3d^6$, 4 unpaired","show_unpaired":true},"children":[]},"ans_b2":{"type":"ElectronBoxes","props":{"groups":[{"boxes":5,"label":"3d","electrons":5}],"caption":"$\\ce{Fe^3+}$: $3d^5$, 5 unpaired","show_unpaired":true},"children":[]}}},"title":"Summary"}],"title":"Unpaired electrons and magnetic moment","minutes":10,"book_ref":"Ch.1 point 4 Magnetic properties, exercises p.14; Evaluation Q4 p.26 and Q7.9 p.27","subtitle":"From a compound's formula to its magnetic moment","objectives":["Find the metal's oxidation state in a compound and write its ion's 3d configuration (4s lost first).","Count unpaired electrons by Hund's rule and classify the compound as paramagnetic or diamagnetic.","Arrange compounds in ascending order of magnetic moment."],"concept_ids":["te.magnetic-moment-from-config"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"$3d^6$ is the iron atom. In these compounds iron has lost electrons, and not the same number: 2 in $\\ce{FeCl2}$ and 3 in $\\ce{FeCl3}$."},{"id":"b","feedback":"More d electrons does not mean more unpaired ones, and the magnetic moment depends on the unpaired electrons."},{"id":"c","feedback":"Good prediction. Let's check it by counting the unpaired electrons of the ion."}],"explanation":"$\\ce{FeCl3}$ has the larger magnetic moment. $\\ce{Fe^{3+}}$ is $3d^5$ with 5 unpaired electrons, while $\\ce{Fe^{2+}}$ is $3d^6$ with 4, and the magnetic moment increases with the number of unpaired electrons."}},"s2":{"m":{"statement":"Pair the electrons first: $d^6$ is three pairs, so 0 unpaired.","correction":"By Hund's rule each electron takes an empty box first. So $d^6$ is $[\\uparrow\\downarrow][\\uparrow][\\uparrow][\\uparrow][\\uparrow]$: 4 unpaired."}},"s3":{"m":{"statement":"For $\\ce{FeCl3}$, use the iron atom: $3d^6$, 4 unpaired.","correction":"In $\\ce{FeCl3}$ iron is $\\ce{Fe^3+}$: it has lost three electrons, so the atom's count is wrong here. The atom's count fits $\\ce{FeCl2}$ instead: $\\ce{Fe^2+}$ is $3d^6$, 4 unpaired."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"By Hund's rule each electron takes an empty box first, so the ion's 3d electrons do not pair up."},{"id":"m2","feedback":"That is the chromium atom's 3d, but in $\\ce{Cr2O3}$ chromium is an ion that has lost electrons."},{"id":"m3","feedback":"By Hund's rule the ion's 3d electrons go one per box, so more than one of them is unpaired."},{"id":"m4","feedback":"Diamagnetic needs every electron paired, and $\\ce{Cr^3+}$ has unpaired electrons."}],"explanation":"$\\ce{Cr^3+}$: $3d^3$ = $[\\uparrow][\\uparrow][\\uparrow][\\ ][\\ ]$. 3 unpaired electrons, so paramagnetic."},"h":{"hints":["Draw five boxes for 3d.","Place the ion's 3d electrons one per box, before any pairing.","Any unpaired electron makes the substance paramagnetic."]}},"s5":{"m":{"statement":"Every transition-metal compound is paramagnetic.","correction":"The ion decides. At +5 vanadium has no 3d electrons left, so $\\ce{V2O5}$ is diamagnetic, while $\\ce{VO}$ is paramagnetic."}},"s6":{"c":{"items":[{"id":"ti","feedback":"Cl is −1, four of them, so titanium is +4, and $\\ce{Ti^4+}$ keeps no 3d electrons."},{"id":"cu1","feedback":"Here copper is +1. Cu is $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$, so after losing 4s it keeps $3d^{10}$, with every 3d electron paired."},{"id":"sc","feedback":"O is −2: three O, two Sc, so Sc is +3, and $\\ce{Sc^3+}$ has nothing left in its 3d."},{"id":"cu2","feedback":"Sulphate is −2, so copper is +2. Copper loses 4s¹ and one 3d, and nine electrons cannot all pair up."},{"id":"ni","feedback":"O is −2, so Ni is +2: $3d^8$ in five boxes leaves two electrons unpaired."}],"explanation":"$\\ce{Ti^4+}$ $3d^0$, $\\ce{Cu+}$ $3d^{10}$, $\\ce{Sc^3+}$ $3d^0$: no unpaired electrons, diamagnetic. $\\ce{Cu^2+}$ $3d^9$ (1) and $\\ce{Ni^2+}$ $3d^8$ (2): paramagnetic."}},"s7":{"h":{"hints":["For each compound, find the metal's oxidation state from the other part's charge.","Remove the 4s electrons first, then 3d electrons for higher states.","Fill the 3d boxes singly first; order by the number of boxes with one electron."]},"o":{"items":[{"id":"ti","feedback":"Titanium is +3 in $\\ce{TiCl3}$, so the ion keeps one 3d electron: 1 unpaired."},{"id":"ni","feedback":"Sulphate is −2, so nickel is $\\ce{Ni^2+}$, $3d^8$: filled by Hund's rule, it has 2 unpaired electrons."},{"id":"co","feedback":"$\\ce{Co^2+}$ is $3d^7$: filled singly first, 3 boxes end up with one electron."},{"id":"mn","feedback":"$\\ce{Mn^2+}$ is $3d^5$: five electrons spread one per box over five boxes, 5 unpaired."}],"explanation":"$\\ce{Ti^3+}$ $3d^1$ (1) < $\\ce{Ni^2+}$ $3d^8$ (2) < $\\ce{Co^2+}$ $3d^7$ (3) < $\\ce{Mn^2+}$ $3d^5$ (5)."}},"s8":{"exam":{"body":"$\\ce{TiO2}$ ($\\ce{Ti^4+}$, $3d^0$, 0) < $\\ce{Cr2O3}$ ($\\ce{Cr^3+}$, $3d^3$, 3) < $\\ce{FeCl3}$ ($\\ce{Fe^3+}$, $3d^5$, 5). Write the ion, its 3d configuration and its unpaired electrons for each.","title":"Arrange by magnetic moment: TiO₂, Cr₂O₃, FeCl₃ (book p.14)"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ $3d^6$ ده بتاع ذرة الـ iron. في الـ compounds دي الـ iron فقد electrons، ومش فقد نفس العدد في الاتنين: 2 في الـ $\\ce{FeCl2}$ و3 في الـ $\\ce{FeCl3}$."},{"id":"b","feedback":"إن الـ d electrons تبقى أكتر مش معناه إن الـ unpaired electrons أكتر، والـ magnetic moment ماشي ورا عدد الـ unpaired electrons."},{"id":"c","feedback":"توقّع حلو. يلا نتأكد منه بإننا نعدّ الـ unpaired electrons بتوع الـ ion."}],"explanation":"الـ $\\ce{FeCl3}$ هو اللي الـ magnetic moment بتاعه أكبر. الـ $\\ce{Fe^{3+}}$ هو $3d^5$ وفيه 5 unpaired electrons، إنما الـ $\\ce{Fe^{2+}}$ هو $3d^6$ وفيه 4، والـ magnetic moment بيزيد بزيادة عدد الـ unpaired electrons."}},"s2":{"m":{"statement":"اعمل أزواج الأول: الـ $d^6$ يبقى 3 أزواج، يعني 0 unpaired.","correction":"حسب الـ Hund's rule كل electron بياخد مربع فاضي الأول. فالـ $d^6$ بيبقى $[\\uparrow\\downarrow][\\uparrow][\\uparrow][\\uparrow][\\uparrow]$: يعني 4 unpaired."}},"s3":{"m":{"statement":"في الـ $\\ce{FeCl3}$ استخدم ذرة الـ iron: $3d^6$، يعني 4 unpaired.","correction":"الـ iron في الـ $\\ce{FeCl3}$ بيبقى $\\ce{Fe^3+}$: يعني فقد 3 electrons، فعدّ الذرة مش هو اللي ينفع هنا. عدّ الذرة ده ييجي مع الـ $\\ce{FeCl2}$: الـ $\\ce{Fe^2+}$ هو $3d^6$، يعني 4 unpaired."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"إنت عملتهم أزواج، لكن حسب الـ Hund's rule كل electron بياخد مربع فاضي الأول قبل أي أزواج."},{"id":"m2","feedback":"ده الـ 3d بتاع ذرة الـ chromium، لكن في الـ $\\ce{Cr2O3}$ الـ chromium عبارة عن ion خسر electrons."},{"id":"m3","feedback":"الـ 3d electrons بتوع الـ ion بيتحطوا واحد في كل مربع حسب الـ Hund's rule، فمش electron واحد لوحده اللي unpaired."},{"id":"m4","feedback":"الـ diamagnetic محتاج كل الـ electrons تكون paired، والـ $\\ce{Cr^3+}$ فيه unpaired electrons."}],"explanation":"$\\ce{Cr^3+}$: $3d^3$ = $[\\uparrow][\\uparrow][\\uparrow][\\ ][\\ ]$. يعني 3 unpaired electrons، فهو paramagnetic."},"h":{"hints":["ارسم خمس مربعات للـ 3d.","حط الـ 3d electrons بتوع الـ ion واحد في كل مربع، قبل أي أزواج.","أي unpaired electron بيخلّي المادة paramagnetic."]}},"s5":{"m":{"statement":"أي compound لـ transition metal بيبقى paramagnetic.","correction":"الـ ion هو اللي بيحدد. عند +5 الـ vanadium مابيفضلش معاه أي 3d electrons، فالـ $\\ce{V2O5}$ بيبقى diamagnetic، إنما الـ $\\ce{VO}$ بيبقى paramagnetic."}},"s6":{"c":{"items":[{"id":"ti","feedback":"الـ Cl بـ −1، وهما أربعة، يعني ده $\\ce{Ti^4+}$ ومش فاضل معاه أي 3d electrons."},{"id":"cu1","feedback":"هنا الـ copper بـ +1. الـ Cu هو $[\\text{Ar}]\\ 4s^1\\ 3d^{10}$، وبعد ما يفقد الـ 4s، الـ $3d^{10}$ كلها paired."},{"id":"sc","feedback":"الـ O بـ −2: تلاتة O واتنين Sc، يعني ده $\\ce{Sc^3+}$ والـ 3d بتاعه فاضي."},{"id":"cu2","feedback":"الـ sulphate بـ −2، يعني الـ copper بـ +2. الـ copper بيفقد الـ 4s¹ وواحد من الـ 3d، والتسعة electrons اللي فاضلين مايقدروش يعملوا أزواج كلهم."},{"id":"ni","feedback":"الـ O بـ −2، يعني الـ Ni بـ +2: $3d^8$. التمانية في الخمس مربعات بيسيبوا 2 unpaired."}],"explanation":"$\\ce{Ti^4+}$ $3d^0$، و$\\ce{Cu+}$ $3d^{10}$، و$\\ce{Sc^3+}$ $3d^0$: مفيهمش unpaired electrons، يعني diamagnetic. أما $\\ce{Cu^2+}$ $3d^9$ (1) و$\\ce{Ni^2+}$ $3d^8$ (2): فدول paramagnetic."}},"s7":{"h":{"hints":["في كل compound، هات الـ oxidation state بتاع الـ metal من الـ charge بتاع الجزء التاني.","شيل الـ 4s electrons الأول، وبعدين 3d electrons للحالات الأعلى.","املا مربعات الـ 3d فرادى الأول؛ ورتّب على حسب عدد المربعات اللي فيها electron واحد."]},"o":{"items":[{"id":"ti","feedback":"الـ titanium في الـ $\\ce{TiCl3}$ بـ +3، والـ ion بيفضل معاه 3d electron واحد بس."},{"id":"ni","feedback":"الـ sulphate بـ −2، يعني ده $\\ce{Ni^2+}$ ($3d^8$)، وفيه 2 unpaired electrons حسب الـ Hund's rule."},{"id":"co","feedback":"الـ $\\ce{Co^2+}$ هو $3d^7$: بعد ما الخمس مربعات ياخدوا electron واحد، اتنين بيعملوا أزواج، فبيفضل 3 unpaired."},{"id":"mn","feedback":"الـ $\\ce{Mn^2+}$ هو $3d^5$: الخمس electrons بيتوزعوا واحد في كل مربع، فكلهم unpaired."}],"explanation":"الترتيب من الأصغر للأكبر: $\\ce{Ti^3+}$ $3d^1$ (1) < $\\ce{Ni^2+}$ $3d^8$ (2) < $\\ce{Co^2+}$ $3d^7$ (3) < $\\ce{Mn^2+}$ $3d^5$ (5)."}},"s8":{"exam":{"body":"$\\ce{TiO2}$ ($\\ce{Ti^4+}$، $3d^0$، 0) < $\\ce{Cr2O3}$ ($\\ce{Cr^3+}$، $3d^3$، 3) < $\\ce{FeCl3}$ ($\\ce{Fe^3+}$، $3d^5$، 5). اكتب لكل واحد الـ ion بتاعه، والـ 3d configuration بتاعته، وعدد الـ unpaired electrons.","title":"رتّب حسب الـ magnetic moment: TiO₂، Cr₂O₃، FeCl₃ (الكتاب ص 14)"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":2,"lesson_no":6,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-magnetism-catalysis","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Magnetic properties and catalytic 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forming","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"From breaking the bonds in $\\ce{H2}$ and $\\ce{Cl2}$","correct":false},{"id":"b","text":"From forming the new H–Cl bonds, which gives out more energy than breaking took","correct":true},{"id":"c","text":"The atoms are destroyed and turn into heat","correct":false}],"question":"Predict: where does the heat come from?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Hydrogen burns in chlorine and gives out heat. Yet the $\\ce{H2}$ and $\\ce{Cl2}$ molecules must first come apart."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Where does the heat come from?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"A reaction breaks the bonds of the reactants and forms new bonds in the products."},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a","label":"break bonds: energy absorbed"},{"to":"c","from":"b","label":"form bonds: energy released"}],"nodes":[{"id":"a","label":"H₂ + Cl₂"},{"id":"b","label":"H, H, Cl, Cl (separate atoms)"},{"id":"c","label":"2HCl"}]},"children":[]},"t2":{"type":"Text","props":{"content":"Breaking a bond **absorbs** energy. Forming a bond **releases** energy."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fl","t","t2","m"]}}},"title":"Break, then form"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"f":750},"elements":{"a":{"type":"Stat","props":{"tone":"neutral","label":"absorbed by breaking","value":"600 kJ"},"children":[]},"t":{"type":"Text","props":{"content":"Made-up numbers: breaking the reactants' bonds absorbs 600 kJ (kilojoules, a unit of energy). Change the energy released by the new bonds."},"children":[]},"gt":{"type":"Callout","props":{"variant":"tip"},"visible":{"gt":600,"$state":"/f"},"children":[]},"lt":{"type":"Callout","props":{"variant":"tip"},"visible":{"lt":600,"$state":"/f"},"children":[]},"sl":{"type":"Slider","props":{"max":900,"min":300,"step":50,"unit":"kJ","label":"energy released by forming bonds","value":{"$bindState":"/f"}},"children":[]},"eqc":{"type":"Callout","props":{"variant":"info"},"visible":{"eq":600,"$state":"/f"},"children":[]},"net":{"type":"Stat","props":{"tone":"brand","unit":"kJ","label":"energy change (ΔH) = absorbed − released","value":{"args":{"f":{"$state":"/f"},"expr":"600 - f","digits":0},"$computed":"calc"}},"children":[]},"row":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["a","net"]},"sgn":{"type":"Text","props":{"size":"sm","content":"Chemists write the energy change, ΔH, as absorbed − released. A minus sign means energy is given out."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","row","sgn","gt","eqc","lt"]}}},"title":"The energy balance"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It releases 800 kJ","correct":false},{"id":"b","text":"It releases 200 kJ","correct":false},{"id":"c","text":"It takes in 200 kJ","correct":true}],"question":"In a reaction, breaking bonds absorbs 500 kJ and forming bonds releases 300 kJ. What is the result?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Breaking the bonds in the reactants releases energy."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tf","q"]}}},"title":"Your turn"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["A reaction = breaking the reactants' bonds + forming the products' bonds.","Breaking bonds absorbs energy; forming bonds releases energy.","The balance is the energy change, ΔH = absorbed − released: negative = given out, positive = taken in."]},"children":[]},"n":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"rv":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Show the answer"}},"children":["rv_t"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","n","self","rv"]},"rv_t":{"type":"Text","props":{"content":"Breaking the bonds in $\\ce{H2}$ and $\\ce{Cl2}$ absorbs energy. Forming the new H–Cl bonds releases more energy than breaking took, so ΔH is negative and the reaction gives out heat."},"children":[]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why hydrogen burning in chlorine gives out heat?"},"children":[]}}},"title":"Summary"}],"title":"Bond breaking and bond forming","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 point 5 Catalytic activity, fig 1-3 (net energy released), p.15","subtitle":"Where the energy of a reaction comes from","objectives":["State that in a reaction the bonds of the reactants break and new bonds form in the products.","Recognize that breaking bonds absorbs energy and forming bonds releases energy.","Decide from the balance whether a reaction gives out or takes in energy."],"concept_ids":["chem.bond-breaking-energy"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"A common idea. But atoms in a bond hold each other, so pulling them apart takes energy in, not out."},{"id":"b","feedback":"Good thinking. Breaking takes energy in; forming gives more out."},{"id":"c","feedback":"Atoms are not destroyed in a chemical reaction: the same atoms appear in the products, and only the bonds between them change."}],"explanation":"Breaking the bonds in $\\ce{H2}$ and $\\ce{Cl2}$ takes energy in; forming the new H–Cl bonds gives energy out. Forming gives out more than breaking took, so heat is given out overall."}},"s2":{"m":{"statement":"Breaking bonds releases energy.","correction":"Bonded atoms hold each other, so pulling them apart **needs** energy. Energy comes out when new bonds form."}},"s3":{"gt":{"body":"More released than absorbed: ΔH is negative and the reaction **gives out** energy as heat."},"lt":{"body":"More absorbed than released: ΔH is positive and the reaction **takes in** energy."},"eqc":{"body":"Released = absorbed: ΔH = 0, no net energy change."}},"s4":{"q":{"options":[{"id":"a","feedback":"That adds the two, but one is energy in and one is energy out, so they are not added."},{"id":"b","feedback":"You found the right size, but the 500 kJ here is absorbed, and it is larger than the 300 kJ released."},{"id":"c","feedback":"Right: 500 kJ in, 300 kJ out, so 200 kJ more is absorbed than released."}],"explanation":"ΔH = absorbed − released = 500 − 300 = +200 kJ. Positive, so the reaction takes in 200 kJ."},"tf":{"explanation":"Breaking bonds absorbs energy, because the atoms hold each other and must be pulled apart. Energy is released when the new bonds form.","feedback_true":"The atoms hold each other, so pulling them apart needs energy put in.","feedback_false":"Right. Breaking bonds absorbs energy; forming bonds releases it."}},"s5":{"n":{"body":"Before any bond can break, colliding molecules need a minimum energy: the activation energy."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"فكرة منتشرة. لكن الذرات اللي بينها bond ماسكة في بعض، فعشان تفصلهم محتاج energy: الكسر بياخد energy مش بيطلّعها."},{"id":"b","feedback":"تفكير حلو. الكسر بياخد energy، والتكوين بيطلّع energy أكتر."},{"id":"c","feedback":"الذرات مش بتتدمر في الـ chemical reaction: نفس الذرات بتظهر في الـ products، واللي بيتغير هو الـ bonds اللي بينهم."}],"explanation":"كسر الـ bonds اللي في الـ $\\ce{H2}$ والـ $\\ce{Cl2}$ بياخد energy، وتكوين الـ bonds الجديدة H–Cl بيطلّع energy. والتكوين بيطلّع أكتر من اللي الكسر خده، فالمحصلة إن فيه حرارة بتطلع."}},"s2":{"m":{"statement":"كسر الـ bonds بيطلّع energy.","correction":"الذرات اللي بينها bond ماسكة في بعض، فعشان تفصلهم **محتاج** energy. الـ energy بتطلع لما الـ bonds الجديدة تتكوّن."}},"s3":{"gt":{"body":"اللي طلع أكتر من اللي اتمص: الـ ΔH بالسالب والـ reaction **بيطلّع** energy على شكل حرارة."},"lt":{"body":"اللي اتمص أكتر من اللي طلع: الـ ΔH بالموجب والـ reaction **بياخد** energy."},"eqc":{"body":"اللي طلع = اللي اتمص: ΔH = 0، يعني مفيش تغيير في الـ energy في المحصلة."}},"s4":{"q":{"options":[{"id":"a","feedback":"كده إنت جمعت الرقمين، مع إن واحد فيهم energy داخلة والتاني energy طالعة، فمينفعش نجمعهم."},{"id":"b","feedback":"المقدار اللي طلّعته صح، لكن الـ energy الداخلة (500 kJ) أكبر من الطالعة (300 kJ)، فالمحصلة مش energy طالعة."},{"id":"c","feedback":"صح: 500 kJ داخلين و300 kJ طالعين، يعني الممتص أكتر من اللي طلع بـ 200 kJ."}],"explanation":"ΔH = absorbed − released = 500 − 300 = +200 kJ. الإشارة موجبة، يعني الـ reaction بيمتص 200 kJ."},"tf":{"explanation":"كسر الـ bonds بيمتص energy، عشان الذرات ماسكة في بعض ولازم تتفصل. الـ energy بتطلع لما الـ bonds الجديدة تتكوّن.","feedback_true":"الذرات ماسكة في بعض، وعشان تفصلهم لازم تدخّل energy، فالكسر مش بيطلّع energy.","feedback_false":"صح. كسر الـ bonds بيمتص energy، وتكوين الـ bonds بيطلّعها."}},"s5":{"n":{"body":"قبل ما أي bond يتكسر، الـ molecules اللي بتخبط في بعض محتاجة أقل قدر من الـ energy: الـ activation energy."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":1,"is_basics":true,"lesson_no":1,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-chem.bond-breaking-energy","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Bond breaking and bond forming: from zero","duration_s":276.2,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.bond-breaking-energy","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Bond breaking and bond forming","duration_s":43.51,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":61,"page_to":61,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-kin.activation-energy","kind":"lesson","version":3,"catalog_version":3,"ord":298,"primary_concept_id":"kin.activation-energy","concepts":[{"concept_id":"kin.activation-energy","role":"primary"}],"title":"Activation energy and energy profile","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Striking gives the molecules the minimum energy they need to start reacting","correct":true},{"id":"b","text":"Striking supplies all the heat that the flame later gives out","correct":false},{"id":"c","text":"Striking pushes air into the match","correct":false}],"question":"Predict: why must you strike it first?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"A burning match gives out a lot of heat. Yet a match does not light by itself: you must strike it."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Strike the match"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Molecules react only when they collide. 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profile"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Activation energy: the minimum amount of energy a molecule must gain to react at collision.","Activation energy: from the reactants **up** to the top of the hump.","Net energy released: from the reactants **down** to the products."]},"children":[]},"n":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"The molecules must first gain the activation energy before they react: striking the match supplies it. The flame then gives out much more heat than the strike put in."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","n","self","rv"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why a match must be struck, though burning gives out heat?"},"children":[]}}},"title":"Summary"}],"title":"Activation energy and energy profile","minutes":5,"book_ref":"Ch.3 Chemical equilibrium, activation energy, pp.61-62 (taught there later); used in Ch.1 point 5 Catalytic activity, fig 1-3, p.15","subtitle":"Why reactions need a start","objectives":["Define activation energy in the book's words.","Explain why only collisions with enough energy lead to a reaction.","Read an energy profile: activation energy versus net energy released."],"concept_ids":["kin.activation-energy"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. That minimum energy has a name. This lesson is about it."},{"id":"b","feedback":"The flame gives out far more heat than a quick strike puts in."},{"id":"c","feedback":"Air is around the match all the time, yet the match does not light by itself."}],"explanation":"The reacting molecules must have a minimum amount of energy before they react: the activation energy. Striking the match supplies it; the flame then gives out much more heat than the strike put in."}},"s3":{"c0":{"body":"Less than the activation energy: the molecules bounce apart. No reaction."},"c1":{"body":"Equal to or more than the activation energy: old bonds break and new bonds form."}},"s4":{"m":{"statement":"Activation energy is the energy the reaction gives out.","correction":"That is the **net energy released**: from the reactants **down** to the products. Activation energy is the climb **up** from the reactants to the top of the hump."}},"s5":{"q":{"options":[{"id":"x","feedback":"Right. X climbs from the reactants to the top of the hump."},{"id":"y","feedback":"Y starts at the products, but the reaction starts at the reactants."},{"id":"z","feedback":"Z compares the reactants with the products: that is the net energy released, not the climb."}],"explanation":"Arrow X goes from the energy of the reactants up to the top of the hump: that climb is the activation energy. Z compares the reactants with the products, and Y starts at the products."},"tf":{"explanation":"The activation energy (the climb to the top of the hump) and the energy released (the drop to the products) are separate. A reaction can release a lot of energy and still need a high activation energy, like a match that needs a strike.","feedback_true":"Like the match, a reaction can give out lots of heat yet need a strike to start: the climb and the drop are separate.","feedback_false":"Right. The hump and the energy released are separate: a big drop can follow a high hump."}},"s6":{"n":{"body":"A catalyst lowers the hump: how transition elements speed up reactions."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. الحد الأدنى ده من الـ energy ليه اسم، والدرس ده عنه."},{"id":"b","feedback":"اللهب بيطلّع حرارة أكتر بكتير من اللي الحكّة السريعة بتدخّلها، فالحكّة مش هي مصدر حرارة اللهب."},{"id":"c","feedback":"الهوا موجود حوالين عود الكبريت طول الوقت، ومع كده مش بيولّع لوحده، فالهوا مش هو اللي ناقص."}],"explanation":"الجزيئات المتفاعلة لازم يكون معاها حد أدنى من الـ energy قبل ما تتفاعل: ودي الـ activation energy. حكّة عود الكبريت هي اللي بتدّيها، وبعدين اللهب بيطلّع حرارة أكتر بكتير من اللي الحكّة دخّلتها."}},"s3":{"c0":{"body":"أقل من الـ activation energy: الجزيئات بتخبط في بعض وترتد زي ما هي. مفيش تفاعل."},"c1":{"body":"مساوية للـ activation energy أو أكتر: الـ bonds القديمة بتتكسر و bonds جديدة بتتكوّن."}},"s4":{"m":{"statement":"الـ activation energy هي الـ energy اللي الـ reaction بيطلّعها.","correction":"دي اسمها **net energy released**: من الـ reactants **نازل** لحد الـ products. أما الـ activation energy فهي الطلعة **لفوق** من الـ reactants لحد قمة الحدبة."}},"s5":{"q":{"options":[{"id":"x","feedback":"صح. الـ X طالع من الـ reactants لحد قمة الحدبة."},{"id":"y","feedback":"الـ Y بيبدأ من الـ products، والـ reaction بيبدأ من الـ reactants."},{"id":"z","feedback":"الـ Z بيقارن الـ reactants بالـ products: ودي الـ net energy released، مش الطلعة اللي الجزيئات محتاجاها عشان تبدأ."}],"explanation":"السهم X طالع من energy الـ reactants لحد قمة الحدبة: والطلعة دي هي الـ activation energy. أما Z فبيقارن الـ reactants بالـ products، و Y بيبدأ من الـ products."},"tf":{"explanation":"الـ activation energy (الطلعة لحد قمة الحدبة) والـ energy اللي بتطلع (النزلة لحد الـ products) حاجتين منفصلين. ممكن reaction يطلّع energy كتير ومع كده يكون محتاج activation energy عالية، زي عود الكبريت اللي محتاج حكّة.","feedback_true":"افتكر عود الكبريت: بيطلّع حرارة كتير، ومع كده محتاج حكّة عشان يبدأ، فالطلعة والنزلة حاجتين منفصلين.","feedback_false":"صح. الحدبة والـ energy اللي بتطلع حاجتين منفصلين: ممكن نزلة كبيرة تيجي بعد حدبة عالية."}},"s6":{"n":{"body":"الـ catalyst بيوطّي الحدبة: وده إزاي الـ transition elements بتسرّع التفاعلات."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":2,"is_basics":true,"lesson_no":2,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-magnetism-catalysis","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Magnetic properties and catalytic activity","duration_s":702.279,"start_s":318.7,"end_s":375,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-kin.activation-energy","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Activation energy and energy profile","duration_s":48.87,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":61,"page_to":62,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.catalytic-activity","kind":"lesson","version":3,"catalog_version":3,"ord":300,"primary_concept_id":"te.catalytic-activity","concepts":[{"concept_id":"te.catalytic-activity","role":"primary"}],"title":"Catalytic activity of transition elements","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It lowers the activation energy, the hump","correct":true},{"id":"b","text":"It makes the reaction release more energy","correct":false},{"id":"c","text":"It reacts with $\\ce{H2O2}$ and is used up","correct":false}],"question":"Predict: what does the $\\ce{MnO2}$ change?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"A pinch of $\\ce{MnO2}$ makes $\\ce{H2O2}$ fizz fast, and the $\\ce{MnO2}$ is still there at the end. 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O₂</text></svg>","max_width":400},"visible":{"eq":1,"$state":"/s"},"children":[]},"d2":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -4 420 264\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><line x1=\"50\" y1=\"18\" x2=\"50\" y2=\"230\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><line x1=\"50\" y1=\"230\" x2=\"390\" y2=\"230\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><text x=\"18\" y=\"124\" font-size=\"13\" fill=\"#94a3b8\" text-anchor=\"middle\" transform=\"rotate(-90 18 124)\">Potential energy</text><text x=\"220.0\" y=\"252\" font-size=\"13\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">Progress of reaction</text><line x1=\"95\" y1=\"115\" x2=\"370\" y2=\"115\" stroke=\"#94a3b8\" stroke-width=\"1.4\" stroke-dasharray=\"4 4\"/><path d=\"M60,115 L95,115 C140,115 145,35 190,35 C235,35 240,195 285,195 L340,195\" fill=\"none\" stroke=\"#fbbf24\" stroke-width=\"3\" stroke-linecap=\"round\"/><line x1=\"178.0\" y1=\"76.0\" x2=\"178.0\" y2=\"113.0\" 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stroke-width=\"3\"/><text x=\"280\" y=\"26\" font-size=\"12\" fill=\"#fbbf24\" text-anchor=\"start\" font-weight=\"700\">without catalyst</text><line x1=\"248\" y1=\"42\" x2=\"274\" y2=\"42\" stroke=\"#2dd4bf\" stroke-width=\"3\" stroke-dasharray=\"7 5\"/><text x=\"280\" y=\"46\" font-size=\"12\" fill=\"#2dd4bf\" text-anchor=\"start\" font-weight=\"700\">with catalyst</text><line x1=\"360.0\" y1=\"155.0\" x2=\"360.0\" y2=\"117.0\" stroke=\"#e2e8f0\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"360.0,117.0 363.5,124.2 356.5,124.2\" fill=\"#e2e8f0\"/><line x1=\"360.0\" y1=\"155.0\" x2=\"360.0\" y2=\"193.0\" stroke=\"#e2e8f0\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"360.0,193.0 356.5,185.8 363.5,185.8\" fill=\"#e2e8f0\"/><text x=\"352\" y=\"150\" font-size=\"12\" fill=\"#e2e8f0\" text-anchor=\"end\" font-weight=\"700\">Net</text><text x=\"352\" y=\"165\" font-size=\"12\" fill=\"#e2e8f0\" text-anchor=\"end\" font-weight=\"700\">energy</text><text x=\"352\" y=\"180\" font-size=\"12\" fill=\"#e2e8f0\" text-anchor=\"end\" font-weight=\"700\">released</text><text x=\"60\" y=\"105\" font-size=\"14\" fill=\"#e2e8f0\" text-anchor=\"start\" font-weight=\"500\">2H₂O₂</text><text x=\"245\" y=\"217\" font-size=\"14\" fill=\"#e2e8f0\" text-anchor=\"start\" font-weight=\"500\">2H₂O + O₂</text></svg>","caption":"Effect of MnO₂ as a catalyst in the decomposition of H₂O₂ (fig 1-3)","max_width":400},"visible":{"eq":2,"$state":"/s"},"children":[]},"sl":{"type":"Slider","props":{"max":2,"min":1,"step":1,"label":"1 = no catalyst, 2 = with $\\ce{MnO2}$","value":{"$bindState":"/s"}},"children":[]},"t2":{"type":"Text","props":{"content":"With $\\ce{MnO2}$ the hump is lower: a lower activation energy, so a faster reaction."},"visible":{"eq":2,"$state":"/s"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","sl","d1","d2","t2","m"]}}},"title":"Fig 1-3, step by step"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"TrueFalse","props":{"answer":false,"statement":"A catalyst gives more product or more energy."},"children":[]},"t":{"type":"Text","props":{"content":"Look at the two ends of the curves in fig 1-3 below. The catalyst does not move them."},"children":[]},"t2":{"type":"Text","props":{"content":"So a catalyst changes only how fast the products form."},"children":[]},"fig":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -4 420 264\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><line x1=\"50\" y1=\"18\" x2=\"50\" y2=\"230\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><line x1=\"50\" y1=\"230\" x2=\"390\" y2=\"230\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><text x=\"18\" y=\"124\" font-size=\"13\" fill=\"#94a3b8\" text-anchor=\"middle\" transform=\"rotate(-90 18 124)\">Potential energy</text><text x=\"220.0\" y=\"252\" font-size=\"13\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">Progress of reaction</text><line x1=\"95\" y1=\"115\" x2=\"370\" y2=\"115\" stroke=\"#94a3b8\" stroke-width=\"1.4\" stroke-dasharray=\"4 4\"/><path d=\"M60,115 L95,115 C140,115 145,35 190,35 C235,35 240,195 285,195 L340,195\" fill=\"none\" stroke=\"#fbbf24\" stroke-width=\"3\" stroke-linecap=\"round\"/><line x1=\"178.0\" y1=\"76.0\" x2=\"178.0\" y2=\"113.0\" stroke=\"#fbbf24\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"178.0,113.0 174.5,105.8 181.5,105.8\" fill=\"#fbbf24\"/><line x1=\"178.0\" y1=\"76.0\" x2=\"178.0\" y2=\"39.0\" stroke=\"#fbbf24\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"178.0,39.0 181.5,46.2 174.5,46.2\" fill=\"#fbbf24\"/><path d=\"M60,115 L95,115 C140,115 145,85 190,85 C235,85 240,195 285,195 L340,195\" fill=\"none\" stroke=\"#2dd4bf\" stroke-width=\"3\" stroke-dasharray=\"7 5\" stroke-linecap=\"round\"/><line x1=\"202.0\" y1=\"101.0\" x2=\"202.0\" y2=\"113.0\" stroke=\"#2dd4bf\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"202.0,113.0 198.5,105.8 205.5,105.8\" fill=\"#2dd4bf\"/><line x1=\"202.0\" y1=\"101.0\" x2=\"202.0\" y2=\"89.0\" stroke=\"#2dd4bf\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"202.0,89.0 205.5,96.2 198.5,96.2\" fill=\"#2dd4bf\"/><line x1=\"248\" y1=\"22\" x2=\"274\" y2=\"22\" stroke=\"#fbbf24\" stroke-width=\"3\"/><text x=\"280\" y=\"26\" font-size=\"12\" fill=\"#fbbf24\" text-anchor=\"start\" font-weight=\"700\">without catalyst</text><line x1=\"248\" y1=\"42\" x2=\"274\" y2=\"42\" stroke=\"#2dd4bf\" stroke-width=\"3\" stroke-dasharray=\"7 5\"/><text x=\"280\" y=\"46\" font-size=\"12\" fill=\"#2dd4bf\" text-anchor=\"start\" font-weight=\"700\">with catalyst</text><line x1=\"360.0\" y1=\"155.0\" x2=\"360.0\" y2=\"117.0\" stroke=\"#e2e8f0\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"360.0,117.0 363.5,124.2 356.5,124.2\" fill=\"#e2e8f0\"/><line x1=\"360.0\" y1=\"155.0\" x2=\"360.0\" y2=\"193.0\" stroke=\"#e2e8f0\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"360.0,193.0 356.5,185.8 363.5,185.8\" fill=\"#e2e8f0\"/><text x=\"352\" y=\"150\" font-size=\"12\" fill=\"#e2e8f0\" text-anchor=\"end\" font-weight=\"700\">Net</text><text x=\"352\" y=\"165\" font-size=\"12\" fill=\"#e2e8f0\" text-anchor=\"end\" font-weight=\"700\">energy</text><text x=\"352\" y=\"180\" font-size=\"12\" fill=\"#e2e8f0\" text-anchor=\"end\" font-weight=\"700\">released</text><text x=\"60\" y=\"105\" font-size=\"14\" fill=\"#e2e8f0\" text-anchor=\"start\" font-weight=\"500\">2H₂O₂</text><text x=\"245\" y=\"217\" font-size=\"14\" fill=\"#e2e8f0\" text-anchor=\"start\" font-weight=\"500\">2H₂O + O₂</text></svg>","caption":"Effect of MnO₂ as a catalyst in the decomposition of H₂O₂ (fig 1-3)","max_width":400},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","fig","m","t2"]}}},"title":"Lower hump, same drop"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Book: transition elements are considered ideal catalysts. The reason is in their **4s and 3d electrons**."},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a"},{"to":"c","from":"b"},{"to":"d","from":"c"},{"to":"e","from":"d"}],"nodes":[{"id":"a","label":"4s and 3d electrons form bonds between surface atoms and reacting molecules"},{"id":"b","label":"Concentration of the molecules on the surface increases"},{"id":"c","label":"Bonds in the reactant molecules weaken"},{"id":"d","label":"Activation energy decreases"},{"id":"e","label":"Speed of reaction increases"}],"layout":"vertical","caption":"Book p.15: the catalytic activity of the first transition series"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","fl"]}}},"title":"Why transition elements?"},{"id":"s5","kind":"interact","spec":{"root":"root","state":{"k":1},"elements":{"u":{"type":"Callout","props":{"variant":"info"},"children":[]},"c1":{"type":"Text","props":{"content":"Molecules arrive. 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chain"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"60 kJ","correct":true},{"id":"b","text":"140 kJ: the 80 kJ saved is given out too","correct":false},{"id":"c","text":"100 kJ, the same as the new activation energy","correct":false}],"question":"With the catalyst, how much net energy is released?"},"children":[]},"t":{"type":"Text","props":{"content":"A new reaction (made-up values): activation energy 180 kJ, net energy released 60 kJ. A catalyst lowers the activation energy to 100 kJ."},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Transition elements are good catalysts simply because they are metals."},"children":[]},"tf2":{"type":"TrueFalse","props":{"answer":false,"statement":"After the reaction, the catalyst has less mass, because it formed bonds with the molecules."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q","tf","tf2"]}}},"title":"New reaction, same rules"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["A catalyst lowers the activation energy, so the reaction is faster (fig 1-3).","Same products, same net energy released; the catalyst is not used up.","Transition elements are ideal catalysts: their 4s and 3d electrons form bonds with reacting molecules on the surface."]},"children":[]},"tbl":{"type":"DataTable","props":{"rows":[["Activation energy","higher","lower"],["Products","$\\ce{2H2O + O2}$","$\\ce{2H2O + O2}$"],["Net energy released","same","same"],["Speed of reaction","slower","faster"]],"caption":"Decomposition of $\\ce{H2O2}$ (fig 1-3)","headers":["","Without catalyst","With $\\ce{MnO2}$"],"highlight":[{"col":2,"row":0},{"col":2,"row":3}]},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tbl","exam","self"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain how $\\ce{MnO2}$ speeds up $\\ce{H2O2}$ and is still there at the end?"},"children":[]}}},"title":"Summary"}],"title":"Catalytic activity of transition elements","minutes":9,"book_ref":"Ch.1 General properties, point 5 Catalytic activity and fig 1-3, pp.14-15; Evaluation Q7.11, p.27","subtitle":"Why transition elements are ideal catalysts","objectives":["Read fig 1-3: a catalyst lowers the activation energy; the net energy released stays the same.","Explain why transition elements are ideal catalysts: their 4s and 3d electrons form bonds with reacting molecules on the surface.","Order the book's reason: bonds to the surface, higher concentration, weaker bonds, lower activation energy, faster reaction.","Refute: a catalyst is not used up and gives no extra product or energy."],"concept_ids":["te.catalytic-activity"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good prediction. The book's fig 1-3 shows exactly this."},{"id":"b","feedback":"A catalyst does not change the energy released: the reactants and the products are the same with or without it, so the energy between them stays the same."},{"id":"c","feedback":"The $\\ce{MnO2}$ is not used up: the same mass of it is found at the end, so it is not a reactant that gets consumed."}],"explanation":"Fig 1-3: with $\\ce{MnO2}$ the hump (the activation energy) is lower, so $\\ce{H2O2}$ decomposes faster. The reactants and products are the same, so the net energy released does not change, and the $\\ce{MnO2}$ is still there at the end."}},"s2":{"m":{"explanation":"In fig 1-3, the activation energy is measured from the reactants up to the top of the hump; the net energy released is measured from the reactants down to the products.","feedback_true":"Not quite. Activation energy is the climb from the reactants to the top of the hump. The energy given out is the drop from the reactants to the products.","feedback_false":"Right. Activation energy is the climb to the top of the hump; the energy given out is the drop from the reactants to the products."}},"s3":{"m":{"explanation":"A catalyst lowers the activation energy. The reactants, the products and the net energy released stay the same, so the same products simply form faster.","feedback_true":"Look at the two ends of the curves in fig 1-3: the reactants and products stay at the same levels, so the net energy released is the same. The catalyst lowers the hump; it does not give more product or more energy.","feedback_false":"Right. The reactants and products stay at the same levels, so the net energy released is the same. The catalyst lowers the hump."}},"s5":{"u":{"body":"The bonds to the surface do not last. The products leave, and the catalyst is left unchanged. That is why it is not used up."}},"s6":{"o":{"items":[{"id":"a","feedback":"These bonds start the chain: without them, nothing holds the molecules on the surface."},{"id":"b","feedback":"The concentration on the surface rises because of the bonds to the surface, so it comes after them."},{"id":"c","feedback":"The molecules' own bonds weaken once they are held on the surface, so this comes after the concentration rises."},{"id":"d","feedback":"The activation energy decreases because the reactant bonds are weaker, so it comes after they weaken."},{"id":"e","feedback":"The speed of reaction is the final result, after the activation energy decreases."}],"explanation":"Bonds to the surface → more molecules on the surface → weaker bonds → lower activation energy → faster reaction."}},"s7":{"q":{"options":[{"id":"a","feedback":"Right. The reactant and product levels don't move, so the net energy released stays the same."},{"id":"b","feedback":"The 80 kJ saved is part of the climb, not the drop. The catalyst lowers the hump, but the reactant and product levels stay where they were, so no extra energy is given out."},{"id":"c","feedback":"100 kJ is the new activation energy: the climb from the reactants to the top of the hump. The net energy released is a different quantity: the drop from the reactants to the products."}],"explanation":"Net energy released = the drop from the reactants to the products. The catalyst lowers the activation energy (180 kJ → 100 kJ) but does not move the reactant and product levels, so the net energy released stays 60 kJ."},"tf":{"explanation":"Book p.15: the catalytic activity of the first transition series comes from their 4s and 3d electrons. They form bonds with the reacting molecules on the surface, which raises the molecules' concentration there, weakens their bonds and lowers the activation energy.","feedback_true":"Being a metal is not the book's reason. The book points to their 4s and 3d electrons, which form bonds between the surface atoms and the reacting molecules.","feedback_false":"Right. The reason is their 4s and 3d electrons, which form bonds with molecules on the surface."},"tf2":{"explanation":"A catalyst is not used up. It bonds to the reacting molecules for a short time, the products leave the surface, and the same mass of catalyst remains at the end.","feedback_true":"The catalyst does not lose mass: the bonds to the surface do not last, the products leave, and the catalyst is left unchanged.","feedback_false":"Right. The products leave and the catalyst is recovered unchanged, with the same mass."}},"s8":{"exam":{"body":"Because of the **4s and 3d electrons**, which form **bonds between the surface atoms and the reacting molecules**. This **increases the concentration** of the molecules on the surface and **weakens their bonds**. So the **activation energy decreases** and the reaction speeds up.","title":"Give reasons: most transition elements have catalytic activity"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"توقّع حلو. شكل 1-3 في الكتاب بيوضّح ده بالظبط."},{"id":"b","feedback":"الـ catalyst مش بيغيّر الـ energy اللي بتطلع: الـ reactants والـ products هما هما بيه أو من غيره، فالـ energy اللي بينهم بتفضل زي ما هي."},{"id":"c","feedback":"الـ $\\ce{MnO2}$ مش بيتستهلك: نفس الكتلة بتاعته بتتلاقى في الآخر، يعني مش reactant بيخلص."}],"explanation":"شكل 1-3: مع الـ $\\ce{MnO2}$ الحدبة (الـ activation energy) بتوطى، فالـ $\\ce{H2O2}$ بيتكسّر أسرع. الـ reactants والـ products هما هما، فالـ net energy released مابتتغيرش، والـ $\\ce{MnO2}$ بيفضل موجود في الآخر."}},"s2":{"m":{"explanation":"في شكل 1-3، الـ activation energy بتتقاس من الـ reactants لفوق لحد قمة الحدبة؛ والـ net energy released بتتقاس من الـ reactants لتحت لحد الـ products.","feedback_true":"لأ، خلّي بالك. الـ activation energy هي الطلعة من الـ reactants لحد قمة الحدبة. أما الـ energy اللي بتطلع فهي النزلة من الـ reactants للـ products.","feedback_false":"صح. الـ activation energy هي الطلعة لقمة الحدبة، والـ energy اللي بتطلع هي النزلة من الـ reactants للـ products."}},"s3":{"m":{"explanation":"الـ catalyst بيوطّي الـ activation energy. الـ reactants والـ products والـ net energy released بيفضلوا زي ما هما، فنفس الـ products بتتكوّن أسرع وخلاص.","feedback_true":"بص على طرفين المنحنيات في شكل 1-3: الـ reactants والـ products فاضلين على نفس المستوى، فالـ net energy released هي هي. الـ catalyst بيوطّي الحدبة، لكن مش بيدّي product أكتر ولا energy أكتر.","feedback_false":"صح. الـ reactants والـ products فاضلين على نفس المستوى، فالـ net energy released هي هي. الـ catalyst بيوطّي الحدبة وخلاص."}},"s5":{"u":{"body":"الـ bonds مع السطح مابتدومش. الـ products بتمشي، والـ catalyst بيفضل زي ما هو من غير ما يتغيّر، وعشان كده مابيتستهلكش."}},"s6":{"o":{"items":[{"id":"a","feedback":"الـ bonds دي هي أول الحلقة: من غيرها مفيش حاجة بتمسك الـ molecules على السطح."},{"id":"b","feedback":"التركيز على السطح بيزيد بسبب الـ bonds مع السطح، فبييجي بعدها."},{"id":"c","feedback":"الـ bonds اللي جوه الـ molecules بتضعف لما تتمسك على السطح، فده بييجي بعد ما التركيز يزيد."},{"id":"d","feedback":"الـ activation energy بتقل عشان الـ bonds بقت أضعف، فده بييجي بعد ما تضعف."},{"id":"e","feedback":"سرعة الـ reaction هي النتيجة الأخيرة، بعد ما الـ activation energy تقل."}],"explanation":"الـ bonds مع السطح، يبقى molecules أكتر على السطح، فالـ bonds اللي جواها تضعف، فالـ activation energy تقل، فالـ reaction يسرع."}},"s7":{"q":{"options":[{"id":"a","feedback":"صح. مستوى الـ reactants والـ products مابيتحركش، فالـ net energy released بتفضل زي ما هي."},{"id":"b","feedback":"الـ 80 kJ اللي اتوفّروا جزء من الطلعة، مش من النزلة. الـ catalyst بيوطّي الحدبة، لكن مستوى الـ reactants والـ products بيفضل مكانه، فمفيش energy زيادة بتطلع."},{"id":"c","feedback":"الـ 100 kJ دي الـ activation energy الجديدة: الطلعة من الـ reactants لقمة الحدبة. أما الـ net energy released فحاجة تانية: النزلة من الـ reactants للـ products."}],"explanation":"الـ net energy released = النزلة من الـ reactants للـ products. الـ catalyst وطّى الـ activation energy (من 180 kJ لـ 100 kJ)، لكن ماحرّكش مستوى الـ reactants والـ products، فالـ net energy released فضلت 60 kJ."},"tf":{"explanation":"الكتاب صفحة 15: الـ catalytic activity بتاعة الـ first transition series جاية من الـ 4s والـ 3d electrons. دول بيكوّنوا bonds مع الـ reacting molecules على السطح، فتركيز الـ molecules هناك بيزيد، والـ bonds اللي جواها بتضعف، والـ activation energy بتقل.","feedback_true":"إنها metals مش هو سبب الكتاب. الكتاب بيقول إن السبب الـ 4s والـ 3d electrons بتاعتها، اللي بتكوّن bonds بين ذرات السطح والـ reacting molecules.","feedback_false":"صح. السبب هو الـ 4s والـ 3d electrons بتاعتها، اللي بتكوّن bonds مع الـ molecules على السطح."},"tf2":{"explanation":"الـ catalyst مش بيتستهلك. بيرتبط بالـ reacting molecules لفترة قصيرة، والـ products بتسيب السطح، ونفس كتلة الـ catalyst بتفضل في الآخر.","feedback_true":"الـ catalyst مابيخسرش من كتلته: الـ bonds اللي مع السطح مابتدومش، الـ products بتمشي، والـ catalyst بيفضل زي ما هو.","feedback_false":"صح. الـ products بتمشي والـ catalyst بيرجع زي ما هو، بنفس الكتلة."}},"s8":{"exam":{"body":"عشان الـ **4s والـ 3d electrons**، اللي بتعمل **bonds بين ذرات السطح والـ molecules اللي بتتفاعل**. ده **بيزوّد الـ concentration** بتاع الـ molecules على السطح و**بيضعّف الـ bonds بتاعتها**. فالـ **activation energy بتقل** والتفاعل بيسرع.","title":"علّل: معظم الـ transition elements ليها catalytic activity"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":3,"lesson_no":7,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-magnetism-catalysis","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Magnetic properties 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needs a temperature of 500 °C","correct":true},{"id":"b","text":"The reaction gives out 500 °C of heat","correct":false},{"id":"c","text":"500 °C is one of the products","correct":false}],"question":"Predict: what does 500 °C over the arrow tell you?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Later in Chapter 1 you will meet:"},"children":[]},"f1":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{3Fe(s) + 4H2O(v) ->[500\\,^{\\circ}C]}\\\\ \\ce{Fe3O4(s) + 4H2(g)}\\end{gathered}"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","f1","q"]}}},"title":"What does 500 °C mean?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{Zn(s) + 2HCl(aq) -> ZnCl2(aq) + H2(g)}"},"children":[]},"t":{"type":"Text","props":{"content":"Read it: solid zinc and hydrochloric acid solution give zinc chloride solution and hydrogen gas."},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"State symbol","definition":"A letter in brackets after a formula that shows the physical state of the substance."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["(s)","solid"],["(l)","liquid"],["(g)","gas"],["(v)","vapour (water as steam)"],["(aq)","aqueous: dissolved in water"]],"headers":["Symbol","Meaning"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["kt","tb","f","t"]}}},"title":"State symbols"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Over and under the arrow go the **conditions**: Δ (heating), a temperature, a pressure or a catalyst."},"children":[]},"f1":{"type":"Formula","props":{"latex":"\\ce{CaCO3(s) ->[\\Delta] CaO(s) + CO2(g)}"},"children":[]},"f2":{"type":"Formula","props":{"latex":"\\ce{2KClO3(s) ->[MnO2][\\Delta] 2KCl(s) + 3O2(g)}"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f1","f2","t","m"]}}},"title":"Over the arrow"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"c","text":"C(s)"},{"id":"w","text":"H₂O(v)"},{"id":"t","text":"1000 °C"},{"id":"co","text":"CO(g)"},{"id":"h","text":"H₂(g)"}],"answer":{"k":["t"],"p":["co","h"],"r":["c","w"]},"prompt":"Sort each part of this equation:","categories":[{"id":"r","label":"Reactant"},{"id":"p","label":"Product"},{"id":"k","label":"Condition"}]},"children":[]},"f":{"type":"FillBlank","props":{"text":"In this reaction, the $\\ce{CO2}$ comes off as a ___, and the $\\ce{CaCl2}$ is ___ in water.","answers":[["gas"],["dissolved","soluble"]],"mistakes":[{"id":"m1","blank":0,"answer":"liquid"},{"id":"m2","blank":0,"answer":"solid"},{"id":"m3","blank":1,"answer":"solid"},{"id":"m4","blank":1,"answer":"insoluble"}]},"children":[]},"fc":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{C(s) + H2O(v) ->[1000\\,^{\\circ}C]}\\\\ \\ce{CO(g) + H2(g)}\\end{gathered}"},"children":[]},"ff":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{CaCO3(s) + 2HCl(aq) ->}\\\\ \\ce{CaCl2(aq) + H2O(l) + CO2(g)}\\end{gathered}"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fc","c","ff","f"]}}},"title":"Read new equations"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["(s) solid, (l) liquid, (g) gas, (v) vapour, (aq) dissolved in water.","Over the arrow: conditions: Δ (heat), temperature, pressure, catalyst.","What is over the arrow is neither a reactant nor a product."]},"children":[]},"n":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_f","ans_t"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","n","self","ans"]},"self":{"type":"Text","props":{"content":"Can you explain why a catalyst is written over the arrow and not with the reactants?"},"children":[]},"ans_f":{"type":"Formula","props":{"latex":"\\ce{2KClO3(s) ->[MnO2][\\Delta] 2KCl(s) + 3O2(g)}"},"children":[]},"ans_t":{"type":"Text","props":{"content":"A catalyst such as $\\ce{MnO2}$ is a condition: it is not used up, so it is on neither side. It is written over the arrow."},"children":[]}}},"title":"Summary"}],"title":"Reading equations: states and conditions","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 equations with states and conditions, e.g. the Haber-Bosch method, p.15, and the iron equations later in the chapter","subtitle":"What the brackets and the arrow tell you","objectives":["Read the state symbols (s), (l), (g), (v) and (aq).","Read what is written over the arrow: heat (Δ), temperature, pressure, catalyst.","Tell reactants and products apart from the conditions."],"concept_ids":["chem.equation-reading"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Right. What is written over the arrow is a condition of the reaction."},{"id":"b","feedback":"What is written over the arrow is not a result of the reaction, so it is not heat given out."},{"id":"c","feedback":"Products come after the arrow, as formulas, and a temperature is not a substance."}],"explanation":"500 °C over the arrow is a condition: the reaction needs this temperature to take place. Products are written after the arrow as formulas, and a temperature is not a substance."}},"s3":{"m":{"statement":"$\\ce{MnO2}$ is a reactant in this reaction.","correction":"$\\ce{MnO2}$ is written over the arrow, so it is a catalyst: it is not used up, and it is on neither side."}},"s4":{"c":{"items":[{"id":"c","feedback":"C(s) is written before the arrow."},{"id":"w","feedback":"H₂O(v) stands on the left of the arrow."},{"id":"t","feedback":"A temperature is not a substance that reacts or forms, and it is written over the arrow."},{"id":"co","feedback":"CO(g) is written after the arrow."},{"id":"h","feedback":"H₂(g) stands on the right of the arrow."}],"explanation":"Reactants before the arrow, products after it, conditions over it."},"f":{"mistakes":[{"id":"m1","feedback":"The letter after $\\ce{CO2}$ is (g), not (l), the letter for a liquid."},{"id":"m2","feedback":"The letter after $\\ce{CO2}$ is (g), not (s), the letter for a solid."},{"id":"m3","feedback":"The symbol after $\\ce{CaCl2}$ is (aq), not (s), so it is not a solid here."},{"id":"m4","feedback":"The symbol after $\\ce{CaCl2}$ is (aq), not (s), and (aq) means aqueous: in water."}],"explanation":"(g) = gas; (aq) = aqueous, dissolved in water."}},"s5":{"n":{"body":"The Haber-Bosch method writes 500 °C, 200 atm and Fe over its arrow."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"صح. اللي بيتكتب فوق السهم ده condition من الـ conditions بتاعة الـ reaction."},{"id":"b","feedback":"اللي مكتوب فوق السهم مش نتيجة طالعة من الـ reaction، فالرقم ده مش heat بتطلع منها."},{"id":"c","feedback":"الـ products بتيجي بعد السهم ومكتوبة على هيئة formulas، والـ temperature مش مادة."}],"explanation":"الـ 500 °C اللي فوق السهم دي condition: يعني الـ reaction محتاجة درجة الحرارة دي عشان تحصل. أما الـ products فبتتكتب بعد السهم على هيئة formulas، والـ temperature مش مادة."}},"s3":{"m":{"statement":"الـ $\\ce{MnO2}$ هنا reactant من الـ reactants.","correction":"الـ $\\ce{MnO2}$ مكتوب فوق السهم، يبقى ده catalyst: مش بيتستهلك، ومش موجود في أي ناحية من الناحيتين."}},"s4":{"c":{"items":[{"id":"c","feedback":"الـ C(s) مكتوب قبل السهم."},{"id":"w","feedback":"الـ H₂O(v) واقف على شمال السهم."},{"id":"t","feedback":"الـ temperature مش مادة بتتفاعل أو بتتكوّن، وهي مكتوبة فوق السهم."},{"id":"co","feedback":"الـ CO(g) مكتوب بعد السهم."},{"id":"h","feedback":"الـ H₂(g) واقف على يمين السهم."}],"explanation":"الـ reactants قبل السهم، والـ products بعده، والـ conditions فوقه."},"f":{"mistakes":[{"id":"m1","feedback":"الحرف اللي بعد الـ $\\ce{CO2}$ هو (g)، مش (l) اللي بيرمز للـ liquid."},{"id":"m2","feedback":"الحرف اللي بعد الـ $\\ce{CO2}$ هو (g)، مش (s) اللي بيرمز للـ solid."},{"id":"m3","feedback":"الـ symbol اللي بعد الـ $\\ce{CaCl2}$ هو (aq)، مش (s)، فهو مش solid هنا."},{"id":"m4","feedback":"الـ symbol اللي بعد الـ $\\ce{CaCl2}$ هو (aq)، مش (s)، والـ (aq) معناها aqueous: يعني في المية."}],"explanation":"الـ (g) يعني gas؛ والـ (aq) يعني aqueous، يعني dissolved في المية."}},"s5":{"n":{"body":"الـ Haber-Bosch method بتكتب 500 °C و 200 atm و Fe فوق السهم بتاعها."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":3,"is_basics":true,"lesson_no":3,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-magnetism-catalysis","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Magnetic properties and catalytic activity","duration_s":702.279,"start_s":489.9,"end_s":601.3,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.equation-reading","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Reading equations: states and conditions","duration_s":43.3,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.ammonia-haber","kind":"lesson","version":4,"catalog_version":3,"ord":304,"primary_concept_id":"chem.ammonia-haber","concepts":[{"concept_id":"chem.ammonia-haber","role":"primary"}],"title":"Haber-Bosch method for ammonia","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Hydrogen","correct":true},{"id":"b","text":"Oxygen","correct":false},{"id":"c","text":"No other gas: nitrogen alone becomes ammonia","correct":false}],"question":"Predict: which gas must react with nitrogen to give $\\ce{NH3}$?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Air is mostly nitrogen. Factories turn it into ammonia, $\\ce{NH3}$, by the Haber-Bosch method."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Ammonia from air"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{N2(g) + 3H2(g) ->[500\\,^{\\circ}C / 200\\,atm,\\ Fe]}\\\\ \\ce{2NH3(g)}\\end{gathered}","caption":"Preparation of ammonia by the Haber-Bosch method (book p.15)"},"children":[]},"t":{"type":"Text","props":{"content":"Read it: nitrogen gas and hydrogen gas give ammonia gas. One $\\ce{N2}$ reacts with three $\\ce{H2}$ to give two $\\ce{NH3}$."},"children":[]},"t2":{"type":"Text","props":{"content":"Over the arrow: 500 °C, a pressure of 200 atm, and iron, Fe, the catalyst. 200 atm (atmospheres) is 200 times normal air pressure."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","t2"]}}},"title":"The book's equation"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"The bond in $\\ce{N2}$ is very strong. Breaking it needs a high activation energy, so the reaction is very slow."},"children":[]},"t2":{"type":"Text","props":{"content":"Iron, a transition element, lowers the activation energy. So ammonia forms fast enough for a factory."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Activation energy","high","lowered"],["Rate of forming ammonia","very slow","fast enough for a factory"]],"caption":"The same reaction without and with iron","headers":["","Without iron","With iron (catalyst)"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","t2","tab","m"]}}},"title":"Why iron is needed"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"4","correct":true},{"id":"b","text":"6","correct":false},{"id":"c","text":"2","correct":false},{"id":"d","text":"12","correct":false}],"question":"In the Haber-Bosch method, 6 molecules of $\\ce{H2}$ react completely with enough $\\ce{N2}$. How many molecules of $\\ce{NH3}$ form?"},"children":[]},"q2":{"type":"MCQ","props":{"options":[{"id":"a","text":"It lowers the activation energy and is not used up","correct":true},{"id":"b","text":"It reacts with nitrogen to form ammonia","correct":false},{"id":"c","text":"It increases the amount of ammonia formed","correct":false}],"question":"Which statement about the iron in the Haber-Bosch method is correct?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","q2"]}}},"title":"Use the equation"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Ammonia is made industrially from nitrogen and hydrogen by the Haber-Bosch method.","$\\begin{gathered}\\ce{N2(g) + 3H2(g) ->[500\\,^{\\circ}C / 200\\,atm,\\ Fe]}\\\\ \\ce{2NH3(g)}\\end{gathered}$","Iron is the catalyst: it lowers the activation energy of this slow reaction."]},"children":[]},"n":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"rv":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Show the answer"}},"children":["rv_t"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","n","self","rv"]},"rv_t":{"type":"Text","props":{"content":"Iron is the catalyst, not a reactant: it lowers the activation energy and speeds up the reaction, but it is not used up and gives no extra ammonia. That is why it sits over the arrow."},"children":[]},"self":{"type":"Text","props":{"content":"Can you explain why iron is written over the arrow and not as a reactant?"},"children":[]}}},"title":"Summary"}],"title":"Haber-Bosch method for ammonia","minutes":5,"book_ref":"Ch.1 point 5 Catalytic activity, p.15 (Haber-Bosch equation); uses of iron, pp.6-7","subtitle":"Making ammonia from nitrogen and hydrogen","objectives":["State that ammonia is made industrially from nitrogen and hydrogen by the Haber-Bosch method.","Read the book's equation with its conditions: 500 °C, 200 atm and iron as the catalyst.","Use the equation's numbers: 3 H₂ give 2 NH₃."],"concept_ids":["chem.ammonia-haber"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Right: $\\ce{NH3}$ is made of N and H, so nitrogen needs hydrogen."},{"id":"b","feedback":"The formula $\\ce{NH3}$ has no oxygen in it."},{"id":"c","feedback":"$\\ce{NH3}$ has two elements, so its H atoms must come from another gas."}],"explanation":"$\\ce{NH3}$ is made of nitrogen and hydrogen, so nitrogen must react with hydrogen: $\\ce{N2 + 3H2 -> 2NH3}$."}},"s3":{"m":{"statement":"Fe is a reactant: it reacts with nitrogen and hydrogen to make ammonia.","correction":"Fe is written over the arrow because it is the catalyst. It is not used up and gives no extra ammonia; it only speeds up the reaction."}},"s4":{"q":{"options":[{"id":"a","feedback":"Right. 3 $\\ce{H2}$ give 2 $\\ce{NH3}$, so 6 $\\ce{H2}$ give twice as many."},{"id":"b","feedback":"$\\ce{H2}$ and $\\ce{NH3}$ are not one to one: in the equation, three $\\ce{H2}$ give two $\\ce{NH3}$."},{"id":"c","feedback":"That is what three $\\ce{H2}$ give, and six $\\ce{H2}$ are two sets of three."},{"id":"d","feedback":"Each $\\ce{NH3}$ needs three H atoms, so 12 counts the H atoms in six $\\ce{H2}$, not the $\\ce{NH3}$ molecules."}],"explanation":"In $\\ce{N2 + 3H2 -> 2NH3}$, three $\\ce{H2}$ give two $\\ce{NH3}$. Six $\\ce{H2}$ are two sets of three, so they give 4 $\\ce{NH3}$."},"q2":{"options":[{"id":"a","feedback":"Right. That is what a catalyst over the arrow does."},{"id":"b","feedback":"$\\ce{NH3}$ has no iron in it: Fe is written over the arrow, not among the reactants."},{"id":"c","feedback":"A catalyst gives no extra product; it changes how fast the reaction goes."}],"explanation":"Iron is the catalyst, written over the arrow: it lowers the activation energy, so the reaction goes faster, and it is not used up. It is not part of $\\ce{NH3}$ and gives no extra product."}},"s5":{"n":{"body":"Iron, nickel and $\\ce{V2O5}$ as catalysts in industry."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"صح: الـ $\\ce{NH3}$ متكوّنة من N و H، يبقى الـ nitrogen محتاج hydrogen."},{"id":"b","feedback":"الـ formula $\\ce{NH3}$ مافيهاش oxygen أصلًا."},{"id":"c","feedback":"الـ $\\ce{NH3}$ فيها عنصرين، فالـ nitrogen لوحده مايقدرش يكوّنها."}],"explanation":"الـ $\\ce{NH3}$ متكوّنة من nitrogen و hydrogen، يبقى الـ nitrogen لازم يتفاعل مع الـ hydrogen: $\\ce{N2 + 3H2 -> 2NH3}$."}},"s3":{"m":{"statement":"الـ Fe ده reactant: بيتفاعل مع الـ nitrogen والـ hydrogen وبيعمل ammonia.","correction":"الـ Fe مكتوب فوق السهم عشان هو الـ catalyst. مش بيتستهلك ومش بيدّي ammonia زيادة، كل شغله إنه بيسرّع الـ reaction."}},"s4":{"q":{"options":[{"id":"a","feedback":"صح. 3 $\\ce{H2}$ بيدّوا 2 $\\ce{NH3}$، يبقى 6 $\\ce{H2}$ بيدّوا الضعف."},{"id":"b","feedback":"الـ $\\ce{H2}$ والـ $\\ce{NH3}$ مش واحد لواحد: في الـ equation، تلاتة $\\ce{H2}$ بيدّوا اتنين $\\ce{NH3}$ بس."},{"id":"c","feedback":"ده اللي بتدّيه تلاتة $\\ce{H2}$ بس، والستة فيها أكتر من مجموعة من تلاتة."},{"id":"d","feedback":"كل $\\ce{NH3}$ محتاج تلات ذرات H، و12 $\\ce{NH3}$ محتاجين 36 ذرة H، والستة $\\ce{H2}$ فيهم 12 ذرة H بس."}],"explanation":"في $\\ce{N2 + 3H2 -> 2NH3}$، تلاتة $\\ce{H2}$ بيدّوا اتنين $\\ce{NH3}$. والستة $\\ce{H2}$ دول مجموعتين من تلاتة، فبيدّوا 4 $\\ce{NH3}$."},"q2":{"options":[{"id":"a","feedback":"صح. ده بالظبط اللي بيعمله الـ catalyst اللي فوق السهم."},{"id":"b","feedback":"الـ $\\ce{NH3}$ مفيهاش iron، والـ Fe مكتوب فوق السهم مش مع المواد اللي بتتفاعل."},{"id":"c","feedback":"الـ catalyst مش بيدّي product زيادة: كمية الـ ammonia مش بتزيد بسببه."}],"explanation":"الـ iron هو الـ catalyst، ومكتوب فوق السهم: بيقلّل الـ activation energy فالـ reaction بيمشي أسرع، ومش بيتستهلك. هو مش جزء من الـ $\\ce{NH3}$ ومش بيدّي product زيادة."}},"s5":{"n":{"body":"الـ iron والـ nickel والـ $\\ce{V2O5}$ كـ catalysts في الصناعة."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":4,"is_basics":true,"lesson_no":4,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-magnetism-catalysis","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Magnetic properties and catalytic activity","duration_s":702.279,"start_s":479.6,"end_s":527.8,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.ammonia-haber","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Haber-Bosch method for ammonia","duration_s":51.37,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-te.catalysis-examples","kind":"lesson","version":5,"catalog_version":3,"ord":306,"primary_concept_id":"te.catalysis-examples","concepts":[{"concept_id":"te.catalysis-examples","role":"primary"}],"title":"Nickel, iron and V₂O₅ as catalysts","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Yes: any transition element speeds up any reaction","correct":false},{"id":"b","text":"No: each process has its own catalyst","correct":true},{"id":"c","text":"No catalyst is needed if the factory heats enough","correct":false}],"question":"Predict: can all three use the same catalyst?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"One factory makes ammonia, one makes sulphuric acid, one turns vegetable oil into solid fat. Each uses a transition-element catalyst."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"One catalyst for all?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"**Finely divided nickel** is used as a catalyst in the hydrogenation of oils. It turns liquid oils into solid fats."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"fat","from":"oil","label":"finely divided Ni (catalyst)"}],"nodes":[{"id":"oil","label":"liquid oil + $\\ce{H2}$"},{"id":"fat","label":"solid fat"}],"layout":"horizontal","caption":"Hydrogenation of oils"},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Hydrogenation","definition":"Adding hydrogen to a substance; here, to oils."},"children":[]},"t2":{"type":"Text","props":{"content":"Finely divided means a very fine powder. A powder has a huge surface, so many surface atoms meet the molecules."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["kt","t","fd","t2"]}}},"title":"Nickel: hydrogenation"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{N2 + 3H2 ->[$\\substack{500\\,^{\\circ}\\mathrm{C} / 200\\,\\mathrm{atm}\\\\ \\mathrm{Fe}}$] 2NH3}","caption":"Book p.15"},"children":[]},"t":{"type":"Text","props":{"content":"Divided iron is used as a catalyst in the preparation of ammonia gas by the **Haber-Bosch method**."},"children":[]},"t2":{"type":"Text","props":{"content":"Iron is also the catalyst in the Fischer-Tropsch method, which turns water gas into a fuel (from iron's uses)."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","f","t2"]}}},"title":"Iron: Haber-Bosch"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Vanadium pentoxide, $\\ce{V2O5}$, is used as a catalyst in the first step:"},"children":[]},"f1":{"type":"Formula","props":{"latex":"\\ce{2SO2 + O2 ->[$\\substack{\\mathrm{V_2O_5}\\\\ 450\\,^{\\circ}\\mathrm{C}}$] 2SO3}"},"children":[]},"f2":{"type":"Formula","props":{"latex":"\\ce{SO3 + H2O -> H2SO4}","caption":"Then sulphur trioxide and water give sulphuric acid."},"children":[]},"kt":{"type":"KeyTerm","props":{"term_en":"Contact method","definition":"The industrial preparation of sulphuric acid."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["kt","t","f1","f2"]}}},"title":"V₂O₅: contact method"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"oil","text":"Vegetable oil + hydrogen → solid fat"},{"id":"nh3","text":"$\\ce{N2 + 3H2 -> 2NH3}$"},{"id":"so3","text":"$\\ce{2SO2 + O2 -> 2SO3}$"},{"id":"h2o2","text":"$\\ce{2H2O2 -> 2H2O + O2}$"},{"id":"ft","text":"Water gas → fuel (Fischer-Tropsch)"}],"answer":{"v":["so3"],"fe":["nh3","ft"],"mn":["h2o2"],"ni":["oil"]},"prompt":"Which catalyst does each reaction or process use?","categories":[{"id":"ni","label":"Finely divided Ni"},{"id":"fe","label":"Fe"},{"id":"v","label":"V₂O₅"},{"id":"mn","label":"MnO₂"}]},"children":[]},"t":{"type":"Text","props":{"content":"Add one you know from fig 1-3: $\\ce{MnO2}$ in the decomposition of $\\ce{H2O2}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","c"]}}},"title":"Match the catalyst"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\small\\ce{2SO2 + O2 + V2O5 -> 2SO3}$","correct":false},{"id":"b","text":"$\\ce{2SO2 + O2 ->[{\\substack{\\mathrm{V_2O_5}\\\\ 450\\,^{\\circ}\\mathrm{C}}}] 2SO3}$","correct":true},{"id":"c","text":"$\\ce{2SO2 + O2 ->[{\\substack{\\mathrm{Fe}\\\\ 450\\,^{\\circ}\\mathrm{C}}}] 2SO3}$","correct":false}],"question":"Which is the correct way to write the first step of the contact method?"},"children":[]},"q2":{"type":"MCQ","props":{"options":[{"id":"a","text":"The catalyst: the Haber-Bosch method uses iron","correct":true},{"id":"b","text":"Nothing: any transition-element catalyst can go over the arrow","correct":false},{"id":"c","text":"$\\ce{V2O5}$ should be written as a reactant","correct":false}],"question":"A student writes $\\ce{N2 + 3H2 ->[V2O5] 2NH3}$. What is wrong?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","q2"]}}},"title":"Spot the error"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"In the Haber-Bosch method the catalyst is ___, at 500 °C and ___ atm.","answers":[["fe","iron","divided iron"],["200"]],"mistakes":[{"id":"m1","blank":0,"answer":"v2o5"},{"id":"m2","blank":0,"answer":"ni"},{"id":"m3","blank":0,"answer":"nickel"},{"id":"m4","blank":1,"answer":"450"}]},"children":[]},"h":{"type":"HintLadder","props":{},"children":[]},"f2":{"type":"FillBlank","props":{"text":"In the contact method the catalyst is ___, at ___ °C.","answers":[["v2o5","vanadium pentoxide","vanadium pent oxide"],["450"]],"mistakes":[{"id":"m1","blank":0,"answer":"fe"},{"id":"m2","blank":0,"answer":"iron"},{"id":"m3","blank":0,"answer":"mno2"},{"id":"m4","blank":1,"answer":"500"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","f2","h"]}}},"title":"Conditions from memory"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Finely divided Ni: hydrogenation of oils.","Fe: Haber-Bosch (500 °C / 200 atm); also Fischer-Tropsch.","$\\ce{V2O5}$: contact method (450 °C). $\\ce{MnO2}$: decomposition of $\\ce{H2O2}$."]},"children":[]},"tbl":{"type":"DataTable","props":{"rows":[["Finely divided Ni","Hydrogenation of oils","oil → solid fat"],["Fe","Haber-Bosch method","500 °C / 200 atm, Fe → $\\ce{NH3}$"],["Fe","Fischer-Tropsch method","water gas → fuel"],["$\\ce{V2O5}$","Contact method","$\\ce{V2O5}$ / 450 °C → $\\ce{SO3}$, then $\\ce{H2SO4}$"],["$\\ce{MnO2}$","Decomposition of $\\ce{H2O2}$ (fig 1-3)","$\\ce{H2O2}$ → $\\ce{H2O + O2}$"]],"caption":"Each process has its own catalyst.","headers":["Catalyst","Process","Over the arrow / product"]},"children":[]},"exam":{"type":"Callout","props":{"variant":"exam"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tbl","exam","self"]},"self":{"type":"Text","props":{"content":"Back to the hook: each process has its own catalyst. Can you explain why the nickel is used as a fine powder?"},"children":[]}}},"title":"Summary"}],"title":"Nickel, iron and V₂O₅ as catalysts","minutes":8,"book_ref":"Ch.1 point 5 Catalytic activity: examples and fig 1-3, pp.14-15; uses of iron and nickel, pp.6-7","subtitle":"Which catalyst for which process","objectives":["Pair finely divided Ni with the hydrogenation of oils and Fe with the Haber-Bosch method.","Pair V₂O₅ with the contact method and MnO₂ with the decomposition of H₂O₂.","Write the Haber-Bosch and contact-method equations with the catalyst and conditions over the arrow.","Explain why the nickel catalyst is finely divided."],"concept_ids":["te.catalysis-examples"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Transition elements are good catalysts, but these three are different reactions, and the book pairs each with its own catalyst."},{"id":"b","feedback":"Right. Each process has its own catalyst. Let's match them."},{"id":"c","feedback":"Heating speeds up reactions, but the book names a catalyst for each of these processes, written over the arrow with the conditions."}],"explanation":"Each process has its own catalyst: finely divided nickel for the hydrogenation of oils, iron for ammonia (Haber-Bosch method) and $\\ce{V2O5}$ for the first step towards sulphuric acid (contact method). Heating alone does not replace the catalyst the book names for each process."}},"s5":{"c":{"items":[{"id":"oil","feedback":"Hydrogen is added to an oil here: this is the hydrogenation of oils."},{"id":"nh3","feedback":"This makes ammonia: it is the Haber-Bosch method, with its catalyst written over the arrow."},{"id":"so3","feedback":"This is the first step towards sulphuric acid: the contact method."},{"id":"h2o2","feedback":"This is the reaction of fig 1-3, where a black powder made it fizz."},{"id":"ft","feedback":"The Fischer-Tropsch method is listed among the uses of the same metal that is the Haber-Bosch catalyst."}],"explanation":"Ni: hydrogenation of oils. Fe: Haber-Bosch and Fischer-Tropsch. V₂O₅: contact method. MnO₂: decomposition of H₂O₂."}},"s6":{"q":{"options":[{"id":"a","feedback":"Here the catalyst is written as a reactant. A catalyst is not used up, so it goes over the arrow, not among the reactants."},{"id":"b","feedback":"Right. The catalyst and the temperature go over the arrow, because the catalyst is not used up."},{"id":"c","feedback":"Iron's catalyst job is making ammonia, not sulphuric acid."}],"explanation":"A catalyst is not used up, so it is written over the arrow with the conditions, not as a reactant. The contact method uses $\\ce{V2O5}$ at 450 °C; iron is the catalyst for ammonia."},"q2":{"options":[{"id":"a","feedback":"Right. $\\ce{V2O5}$ belongs to the contact method; ammonia needs Fe."},{"id":"b","feedback":"Each process has its own catalyst, so not just any transition-element catalyst can go over the arrow."},{"id":"c","feedback":"A catalyst is never a reactant: it is not used up. Here $\\ce{V2O5}$ is already over the arrow, where a catalyst belongs."}],"explanation":"The catalyst over the arrow does not belong to this process: $\\ce{V2O5}$ is the contact method's catalyst, and the Haber-Bosch method uses iron. Over the arrow is where a catalyst goes, because it is not used up."}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"That oxide works in the contact method, for sulphuric acid, not in making ammonia."},{"id":"m2","feedback":"Nickel works with oils and hydrogen, not over the ammonia arrow."},{"id":"m3","feedback":"Nickel works with oils and hydrogen, not over the ammonia arrow."},{"id":"m4","feedback":"450 °C is a temperature from the contact method, and this blank asks for the ammonia pressure in atm."}],"explanation":"The Haber-Bosch method uses iron (Fe) as the catalyst, at 500 °C and 200 atm, all written over the arrow."},"h":{"hints":["Each process has its own catalyst. Picture each equation: what is written over its arrow?","Ammonia's catalyst is a metal; the contact method's catalyst is an oxide.","The two temperatures in this lesson are 500 °C and 450 °C."]},"f2":{"mistakes":[{"id":"m1","feedback":"Iron is the ammonia catalyst; the contact method for sulphuric acid uses an oxide."},{"id":"m2","feedback":"Iron is the ammonia catalyst; the contact method for sulphuric acid uses an oxide."},{"id":"m3","feedback":"$\\ce{MnO2}$ decomposes $\\ce{H2O2}$; it is not the contact method catalyst."},{"id":"m4","feedback":"500 °C is the Haber-Bosch temperature, not the one written for $\\ce{SO2}$ and $\\ce{O2}$."}],"explanation":"The contact method uses $\\ce{V2O5}$ as the catalyst, at 450 °C, written over the arrow."}},"s8":{"exam":{"body":"Write the catalyst and the conditions **over the arrow**, never as a reactant. Fe goes with ammonia; $\\ce{V2O5}$ goes with sulphuric acid.","title":"Exam tip: catalysts in equations"}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ transition elements فعلًا catalysts كويسة، لكن التلات تفاعلات دول مختلفين، والكتاب بيربط كل واحد فيهم بالـ catalyst بتاعه."},{"id":"b","feedback":"صح. كل عملية ليها الـ catalyst بتاعها. يلا نوصّلهم ببعض."},{"id":"c","feedback":"التسخين بيسرّع التفاعلات، لكن الكتاب بيحدد catalyst لكل عملية من دول، بيتكتب فوق السهم مع الظروف."}],"explanation":"كل عملية ليها الـ catalyst بتاعها: الـ finely divided nickel للـ hydrogenation of oils، والـ iron للـ ammonia (الـ Haber-Bosch method)، والـ $\\ce{V2O5}$ لأول خطوة في طريق الـ sulphuric acid (الـ contact method). والتسخين لوحده مش بيغني عن الـ catalyst اللي الكتاب حدده لكل عملية."}},"s5":{"c":{"items":[{"id":"oil","feedback":"إضافة hydrogen على زيت دي الـ hydrogenation of oils، والـ catalyst بتاعها غير بتاع الـ ammonia والـ sulphuric acid."},{"id":"nh3","feedback":"التفاعل ده بيعمل ammonia، يعني ده الـ Haber-Bosch method، والـ catalyst بتاعه هو اللي مكتوب فوق السهم في معادلته."},{"id":"so3","feedback":"دي أول خطوة في طريق الـ sulphuric acid، يعني الـ contact method."},{"id":"h2o2","feedback":"ده التفاعل اللي في شكل 1-3، واللي خلّاه يفوّر هي البودرة السودا اللي اتضافت عليه."},{"id":"ft","feedback":"الـ Fischer-Tropsch method اتذكرت مع استخدامات نفس الـ metal اللي بيشتغل في تحضير الـ ammonia."}],"explanation":"الـ Ni: الـ hydrogenation of oils. الـ Fe: الـ Haber-Bosch والـ Fischer-Tropsch. الـ V₂O₅: الـ contact method. الـ MnO₂: تفكيك الـ H₂O₂."}},"s6":{"q":{"options":[{"id":"a","feedback":"هنا الـ catalyst اتكتب كأنه reactant. الـ catalyst مابيتستهلكش، فمكانه فوق السهم، مش مع الـ reactants."},{"id":"b","feedback":"صح. الـ catalyst والـ temperature بيتكتبوا فوق السهم، عشان الـ catalyst مابيتستهلكش."},{"id":"c","feedback":"شغلانة الـ iron كـ catalyst هي تحضير الـ ammonia، مش الـ sulphuric acid."}],"explanation":"الـ catalyst مابيتستهلكش، فبيتكتب فوق السهم مع الظروف، مش كـ reactant. والـ contact method بيستخدم الـ $\\ce{V2O5}$ عند 450 °C؛ أما الـ iron فهو الـ catalyst بتاع الـ ammonia."},"q2":{"options":[{"id":"a","feedback":"صح. الـ $\\ce{V2O5}$ بتاع الـ contact method، والـ ammonia محتاجة الـ Fe."},{"id":"b","feedback":"كل عملية ليها الـ catalyst بتاعها، فمش أي catalyst من الـ transition elements ينفع يتكتب فوق السهم."},{"id":"c","feedback":"الـ catalyst عمره ما بيبقى reactant: هو مابيتستهلكش. وهنا الـ $\\ce{V2O5}$ مكتوب فوق السهم أصلًا، وده مكانه الصح."}],"explanation":"الـ catalyst اللي فوق السهم مش بتاع العملية دي: الـ $\\ce{V2O5}$ هو الـ catalyst بتاع الـ contact method، والـ Haber-Bosch method بيستخدم الـ iron. ومكان الـ catalyst فعلًا فوق السهم، عشان هو مابيتستهلكش."}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"الـ oxide ده شغله في الـ contact method، بتاعة الـ sulphuric acid، مش في تحضير الـ ammonia."},{"id":"m2","feedback":"الـ nickel شغله مع الزيوت والـ hydrogen، مش مع الـ ammonia؛ الـ Haber-Bosch ليه metal تاني فوق السهم."},{"id":"m3","feedback":"الـ nickel شغله مع الزيوت والـ hydrogen، مش مع الـ ammonia؛ الـ Haber-Bosch ليه metal تاني فوق السهم."},{"id":"m4","feedback":"الـ 450 °C دي temperature من الـ contact method، والفراغ ده مكانه الـ pressure بالـ atm بتاع الـ ammonia."}],"explanation":"الـ Haber-Bosch method بيستخدم الـ iron (Fe) كـ catalyst عند 500 °C و200 atm، وكلهم بيتكتبوا فوق السهم."},"h":{"hints":["كل عملية ليها الـ catalyst بتاعها. تخيّل كل equation: إيه اللي مكتوب فوق السهم بتاعها؟","الـ catalyst بتاع الـ ammonia هو metal؛ والـ catalyst بتاع الـ contact method هو oxide.","الـ temperatures اللي في الدرس ده اتنين: 500 °C و450 °C."]},"f2":{"mistakes":[{"id":"m1","feedback":"الـ iron هو الـ catalyst بتاع الـ ammonia، مش بتاع الـ sulphuric acid، والـ contact method بيستخدم oxide."},{"id":"m2","feedback":"الـ iron هو الـ catalyst بتاع الـ ammonia، مش بتاع الـ sulphuric acid، والـ contact method بيستخدم oxide."},{"id":"m3","feedback":"الـ $\\ce{MnO2}$ بيفكّك الـ $\\ce{H2O2}$، ومش هو الـ oxide اللي بيشتغل في الـ contact method."},{"id":"m4","feedback":"الـ 500 °C دي temperature الـ Haber-Bosch، مش الـ temperature اللي بتتكتب مع الـ $\\ce{SO2}$ والـ $\\ce{O2}$."}],"explanation":"الـ contact method بيستخدم الـ $\\ce{V2O5}$ كـ catalyst عند 450 °C، وبيتكتب فوق السهم."}},"s8":{"exam":{"body":"اكتب الـ catalyst والظروف **فوق السهم**، ومتكتبوش أبدًا كـ reactant. الـ Fe مع الـ ammonia، والـ $\\ce{V2O5}$ مع الـ sulphuric acid.","title":"نصيحة للامتحان: الـ catalysts في المعادلات"}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":4,"lesson_no":8,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-te-magnetism-catalysis","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Magnetic properties and catalytic 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2026-2027)","page_from":6,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.elements-compounds-mixtures","kind":"lesson","version":3,"catalog_version":3,"ord":337,"primary_concept_id":"chem.elements-compounds-mixtures","concepts":[{"concept_id":"chem.elements-compounds-mixtures","role":"primary"}],"title":"Elements, compounds and mixtures","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Yes: the iron is still there, so the magnet still works","correct":false},{"id":"b","text":"No: iron and sulphur are now chemically joined in a new substance","correct":true},{"id":"c","text":"Only after the black solid is dissolved in water","correct":false}],"question":"Predict: can the magnet still pull the iron out of the black solid?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Mix grey iron filings with yellow sulphur powder. A magnet pulls the iron out. Now heat a fresh mixture strongly. A black solid forms."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Mixed or combined?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 338 196\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"10\" y=\"30\" width=\"150\" height=\"130\" rx=\"12\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\"/><text x=\"85.0\" y=\"20\" text-anchor=\"middle\" font-size=\"14\" font-weight=\"700\" fill=\"#fbbf24\">Element: Fe</text><circle cx=\"32.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"59.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"86.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"113.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"140.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"32.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"59.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"86.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"113.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"140.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"32.0\" cy=\"108.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"59.0\" cy=\"108.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" 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width=\"150\" height=\"130\" rx=\"12\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\"/><text x=\"249.0\" y=\"20\" text-anchor=\"middle\" font-size=\"14\" font-weight=\"700\" fill=\"#fbbf24\">Compound: FeS</text><circle cx=\"196.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"212.0\" cy=\"52.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"242.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"258.0\" cy=\"52.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"288.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"304.0\" cy=\"52.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"196.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"212.0\" cy=\"80.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"242.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"258.0\" cy=\"80.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"288.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"304.0\" cy=\"80.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"196.0\" cy=\"108.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"212.0\" cy=\"108.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"242.0\" cy=\"108.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" 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cy=\"136.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"20\" cy=\"182\" r=\"7\" fill=\"#9ca3af\"/><text x=\"32\" y=\"187\" text-anchor=\"start\" font-size=\"12\" font-weight=\"500\" fill=\"#94a3b8\">iron atom</text><circle cx=\"120\" cy=\"182\" r=\"7\" fill=\"#facc15\"/><text x=\"132\" y=\"187\" text-anchor=\"start\" font-size=\"12\" font-weight=\"500\" fill=\"#94a3b8\">sulphur atom</text></svg>","max_width":380},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Compound","definition":"A substance formed of two or more elements chemically combined in a fixed ratio."},"children":[]},"t":{"type":"Text","props":{"content":"A compound has new properties. FeS is black: not grey like iron, not yellow like sulphur. It always has 1 Fe for 1 S."},"children":[]},"t0":{"type":"Text","props":{"content":"An element has one kind of atom, like Fe or S."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","t0","k","t"]}}},"title":"A compound is a new substance"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 502 196\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"10\" y=\"30\" width=\"150\" height=\"130\" rx=\"12\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\"/><text x=\"85.0\" y=\"20\" text-anchor=\"middle\" font-size=\"14\" font-weight=\"700\" fill=\"#fbbf24\">Element: Fe</text><circle cx=\"32.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"59.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"86.0\" cy=\"52.0\" r=\"9\" fill=\"#9ca3af\" 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stroke-width=\"1\"/><circle cx=\"59.0\" cy=\"108.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"86.0\" cy=\"108.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"113.0\" cy=\"108.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"140.0\" cy=\"108.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"32.0\" cy=\"136.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"59.0\" cy=\"136.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"86.0\" cy=\"136.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"113.0\" cy=\"136.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"140.0\" 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fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"196.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"212.0\" cy=\"80.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"242.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"258.0\" cy=\"80.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"288.0\" cy=\"80.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"304.0\" cy=\"80.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"196.0\" cy=\"108.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"212.0\" cy=\"108.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" 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cy=\"136.0\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"304.0\" cy=\"136.0\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><rect x=\"338\" y=\"30\" width=\"150\" height=\"130\" rx=\"12\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"1.5\"/><text x=\"413.0\" y=\"20\" text-anchor=\"middle\" font-size=\"14\" font-weight=\"700\" fill=\"#fbbf24\">Mixture: Fe + S</text><circle cx=\"382.1\" cy=\"100.4\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"427.8\" cy=\"52.6\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"355.6\" cy=\"129.7\" r=\"9\" fill=\"#9ca3af\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"384.6\" cy=\"69.4\" r=\"9\" fill=\"#facc15\" fill-opacity=\"0.85\" stroke=\"#e2e8f0\" stroke-width=\"1\"/><circle cx=\"471.5\" cy=\"93.0\" r=\"9\" fill=\"#9ca3af\" 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atom</text></svg>","max_width":440},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Mixture","definition":"Two or more substances mixed physically. Each keeps its own properties, and they can be separated by physical means."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Ratio of the parts","fixed","can change"],["Properties","new ones","each part keeps its own"],["Separation","not by physical means","by physical means (a magnet, a filter...)"]],"headers":["","Compound","Mixture"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","k","tb","m"]}}},"title":"A mixture is just mixed"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"water","text":"Water, $\\ce{H2O}$"},{"id":"salt","text":"Salt water"},{"id":"cu","text":"Copper, Cu"},{"id":"air","text":"Air"},{"id":"co2","text":"Carbon dioxide, $\\ce{CO2}$"},{"id":"sand","text":"Iron filings and sand"}],"answer":{"cp":["water","co2"],"el":["cu"],"mx":["salt","air","sand"]},"prompt":"Sort each substance.","categories":[{"id":"el","label":"Element"},{"id":"cp","label":"Compound"},{"id":"mx","label":"Mixture"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A compound, because it contains iron and oxygen","correct":false},{"id":"b","text":"A mixture: the $\\ce{Fe2O3}$ and the sand each keep their properties","correct":true},{"id":"c","text":"An element, because it is mostly iron","correct":false}],"question":"A rock contains the compound $\\ce{Fe2O3}$ with sand spread through it. How is the whole rock best described?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Element, compound or mixture?"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["**Element**: one kind of atom (Fe, S, O).","**Compound**: elements chemically combined in a fixed ratio, with new properties ($\\ce{FeS}$, $\\ce{Fe2O3}$).","**Mixture**: substances mixed physically. Each keeps its properties, and physical means separate them."]},"children":[]},"n":{"type":"Text","props":{"muted":true,"content":"Next: iron is found in ores: iron compounds, mostly oxides, mixed with impurities (unwanted substances)."},"children":[]},"t":{"type":"Text","props":{"content":"Can you explain why a magnet separates iron from an iron-sulphur mixture, but not from FeS?"},"children":[]},"rv":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Show the answer"}},"children":["rv_t"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","t","rv","n"]},"rv_t":{"type":"Text","props":{"content":"In the mixture, iron is only mixed physically and keeps its properties, so a magnet pulls it out. In $\\ce{FeS}$, iron is chemically combined with sulphur in a new substance with new properties, so the magnet cannot pull the iron out."},"children":[]}}},"title":"Summary"}],"title":"Elements, compounds and mixtures","minutes":5,"book_ref":"Prerequisite (preparatory science); used in Ch.1 'IRON', p.16: iron ores are iron compounds, mostly oxides, mixed with impurities","subtitle":"Chemically combined, or just mixed?","objectives":["Tell an element, a compound and a mixture apart.","State that a compound has a fixed ratio and new properties.","State that a mixture keeps the properties of its parts and is separated by physical means."],"concept_ids":["chem.elements-compounds-mixtures"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"The iron atoms are still there, but after heating they are no longer free iron."},{"id":"b","feedback":"Good thinking. Heating joined them into a new substance, iron(II) sulphide, FeS."},{"id":"c","feedback":"Water will not free the iron from the black solid."}],"explanation":"The magnet can no longer pull the iron out: heating joined iron and sulphur chemically into a new substance, iron(II) sulphide, FeS, with its own properties."}},"s3":{"m":{"statement":"A mixture and a compound are the same thing.","correction":"In a mixture the parts are not bonded, so their ratio can change. In a compound the elements are chemically combined in a fixed ratio."}},"s4":{"c":{"items":[{"id":"water","feedback":"Hydrogen and oxygen are bonded in a fixed 2 : 1 ratio; with another ratio it would not be water."},{"id":"salt","feedback":"You can stir in more or less salt, so the ratio is not fixed."},{"id":"cu","feedback":"Cu contains one kind of atom."},{"id":"air","feedback":"Oxygen and nitrogen in air keep their own properties and are not bonded to each other."},{"id":"co2","feedback":"Carbon and oxygen are bonded in a fixed 1 : 2 ratio: two kinds of atom, joined."},{"id":"sand","feedback":"A magnet can still pull the iron out, so the iron is not bonded to the sand."}],"explanation":"Copper is an element: one kind of atom. Water and carbon dioxide are compounds: their elements are bonded in a fixed ratio. Salt water, air, and iron filings with sand are mixtures: their parts are not bonded and keep their own properties."},"q":{"options":[{"id":"a","feedback":"$\\ce{Fe2O3}$ itself is a compound, but the sand is not bonded to it, and the amount of sand can vary."},{"id":"b","feedback":"Right. The sand is only mixed in, so the rock is a mixture."},{"id":"c","feedback":"An element has one kind of atom, and this rock has several kinds."}],"explanation":"The whole rock is a mixture: the compound $\\ce{Fe2O3}$ and the sand are not bonded to each other, each keeps its properties, and the amount of sand can vary."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"ذرات الـ iron لسه موجودة فعلًا، لكن الحرارة غيّرتها ومابقتش حرّة زي الأول."},{"id":"b","feedback":"تفكير حلو. التسخين خلّاهم يتحدوا ويكوّنوا مادة جديدة: الـ iron(II) sulphide، FeS."},{"id":"c","feedback":"المية مش هتحرّر الـ iron، لأن الحرارة هي اللي غيّرت الـ iron والـ sulphur."}],"explanation":"المغناطيس مش هيقدر يسحب الـ iron تاني: التسخين خلّى الـ iron والـ sulphur يتحدوا كيميائيًا ويكوّنوا مادة جديدة، الـ iron(II) sulphide، FeS، ليها properties خاصة بيها."}},"s3":{"m":{"statement":"الـ mixture والـ compound حاجة واحدة.","correction":"في الـ mixture المكوّنات مش مرتبطة ببعض، فنسبتها ممكن تتغيّر. إنما في الـ compound الـ elements مرتبطة ببعض كيميائيًا بنسبة ثابتة."}},"s4":{"c":{"items":[{"id":"water","feedback":"الـ hydrogen والـ oxygen مرتبطين ببعض بنسبة ثابتة 2 : 1، ولو النسبة اتغيّرت مايبقاش اللي معاك مية."},{"id":"salt","feedback":"تقدر تقلّب فيها ملح أكتر أو أقل، فالنسبة مش ثابتة."},{"id":"cu","feedback":"الـ Cu فيه نوع واحد من الذرات."},{"id":"air","feedback":"الـ oxygen والـ nitrogen اللي في الهوا محتفظين بالـ properties بتاعتهم ومش مرتبطين ببعض."},{"id":"co2","feedback":"الـ carbon والـ oxygen، نوعين من الذرات، مرتبطين ببعض دايمًا بنسبة 1 : 2."},{"id":"sand","feedback":"المغناطيس لسه يقدر يسحب الـ iron منها، يعني الـ iron محتفظ بالـ properties بتاعته ومش مرتبط بالرمل."}],"explanation":"الـ copper ده element: نوع واحد من الذرات. الـ water والـ carbon dioxide دول compounds: العناصر فيهم مرتبطة ببعض بنسبة ثابتة. أما الـ salt water والـ air والـ iron filings مع الـ sand فدول mixtures: مكوّناتها مش مرتبطة ببعض ومحتفظة بالـ properties بتاعتها."},"q":{"options":[{"id":"a","feedback":"الـ $\\ce{Fe2O3}$ نفسه compound، لكن الرمل مش مرتبط بيه وكميته ممكن تختلف، فالصخرة كلها مش compound واحد."},{"id":"b","feedback":"صح. الرمل مجرد متخلط فيها، يبقى الصخرة دي mixture."},{"id":"c","feedback":"الـ element فيه نوع واحد من الذرات، والصخرة دي فيها أكتر من نوع."}],"explanation":"الصخرة كلها mixture: الـ compound $\\ce{Fe2O3}$ والرمل مش مرتبطين ببعض، وكل واحد فيهم محتفظ بالـ properties بتاعته، وكمية الرمل ممكن تختلف."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":1,"is_basics":true,"lesson_no":1,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-chem.elements-compounds-mixtures","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Elements, compounds and mixtures: from 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(English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.occurrence","kind":"lesson","version":3,"catalog_version":3,"ord":339,"primary_concept_id":"fe.occurrence","concepts":[{"concept_id":"fe.occurrence","role":"primary"}],"title":"Iron: abundance and suitability of iron ore","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{^{56}_{26}Fe}\\;:\\;[\\text{Ar}]\\,4s^{2}\\,3d^{6}"},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Yes: we use so much iron, it must be the most common","correct":false},{"id":"b","text":"No: three elements are more abundant than iron","correct":true},{"id":"c","text":"No: iron is rare, under 1% of the crust","correct":false}],"question":"Predict: is iron also the most abundant element in Earth's crust?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Iron is the most important metal in heavy industries. Bridges, cars and machines need it."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","q"]}}},"title":"Important, but how common?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -8 375 300\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"150\" cy=\"150\" r=\"130\" fill=\"#7c2d12\" fill-opacity=\"0.35\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><circle cx=\"150\" cy=\"150\" r=\"122\" fill=\"#9a3412\" fill-opacity=\"0.35\"/><circle cx=\"150\" cy=\"150\" r=\"62\" fill=\"#9ca3af\" fill-opacity=\"0.55\" stroke=\"#e2e8f0\" stroke-width=\"1.5\"/><line x1=\"190.0\" y1=\"15.0\" x2=\"180.0\" y2=\"26.0\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-linecap=\"round\"/><polygon points=\"180.0,26.0 181.7,20.2 185.6,23.8\" fill=\"#94a3b8\"/><text x=\"194\" y=\"14\" text-anchor=\"start\" font-size=\"13\" font-weight=\"500\" fill=\"#e2e8f0\">crust (thin outer layer)</text><text x=\"150\" y=\"155\" text-anchor=\"middle\" font-size=\"15\" font-weight=\"700\" fill=\"#0f172a\">core</text><line x1=\"278.0\" y1=\"220.0\" x2=\"202.0\" y2=\"180.0\" stroke=\"#fbbf24\" stroke-width=\"3\" stroke-linecap=\"round\"/><polygon points=\"202.0,180.0 212.0,180.3 207.9,188.0\" fill=\"#fbbf24\"/><text x=\"290\" y=\"248\" text-anchor=\"middle\" font-size=\"13\" font-weight=\"700\" fill=\"#fbbf24\">more iron as we</text><text x=\"290\" y=\"264\" text-anchor=\"middle\" font-size=\"13\" font-weight=\"700\" fill=\"#fbbf24\">come close to the core</text></svg>","caption":"The mass of iron increases gradually as we come close to Earth's core.","max_width":360},"children":[]},"s":{"type":"Stat","props":{"tone":"brand","label":"Iron in Earth's crust","value":"5% by mass"},"children":[]},"t":{"type":"Text","props":{"content":"Iron is the **fourth** most abundant element in Earth's crust, after oxygen, silicon and aluminum."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","s","d"]}}},"title":"Fourth in the crust"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"k":{"type":"KeyTerm","props":{"term_en":"Iron ore","definition":"A natural material in the earth's crust that contains iron compounds, mostly iron oxides, mixed with impurities (unwanted substances)."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"c1":{"type":"Card","props":{"title":"Meteorites (rocks from space)"},"children":["c1t"]},"c2":{"type":"Card","props":{"title":"Earth's crust"},"children":["c2t"]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"x","from":"o"},{"to":"fe","from":"x"}],"nodes":[{"id":"o","label":"Iron ore: iron compounds + impurities"},{"id":"x","label":"Extraction"},{"id":"fe","label":"Iron metal"}],"layout":"horizontal","caption":"In the crust, iron comes as ore, not as metal"},"children":[]},"c1t":{"type":"Text","props":{"content":"Iron is found as pure metal (90%) only in meteorites."},"children":[]},"c2t":{"type":"Text","props":{"content":"Iron is found in natural ores, not as metal."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","k","fd","m"]}}},"title":"Pure metal? Only from space"},{"id":"s4","kind":"interact","spec":{"root":"root","elements":{"o":{"type":"Ordering","props":{"items":[{"id":"o","text":"Oxygen"},{"id":"si","text":"Silicon"},{"id":"al","text":"Aluminum"},{"id":"fe","text":"Iron"}],"prompt":"Order these elements from most to least abundant in Earth's crust."},"children":[]},"t":{"type":"Text","props":{"content":"Quick recall before we move on."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","o"]}}},"title":"Rank the crust's elements"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"r":{"type":"Reveal","props":{"label":"Is the iron percentage enough?"},"children":["b2","m"]},"t":{"type":"Text","props":{"content":"Not every iron ore is worth extracting. The first factor in its **suitability**:"},"children":[]},"b1":{"type":"BulletList","props":{"items":["**1)** The iron percentage in the ore."]},"children":[]},"b2":{"type":"BulletList","props":{"items":["**2)** The composition of the impurities in the ore.","**3)** The type of harmful elements mixed with the ore, such as sulphur, phosphorus and arsenic."]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","b1","r"]}}},"title":"Is this ore worth using?"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"From space: it is a meteorite","correct":true},{"id":"b","text":"From an iron ore deposit in the Western Desert","correct":false},{"id":"c","text":"From deep in the crust, where iron is more abundant","correct":false}],"question":"A lump of metal that is 90% iron is found lying on the ground. Where did it most likely come from?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Iron is the most abundant metal in Earth's crust."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Meteorite or mine?"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Correct: the iron percentage is the only factor","correct":false},{"id":"b","text":"Not so fast: the harmful elements and the impurities also decide suitability","correct":true},{"id":"c","text":"Wrong: an ore with less iron is always easier to use","correct":false}],"question":"A student says: \"Ore X is surely more suitable, because it has more iron.\" What is the best reply?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"Name one harmful element that can be mixed with an iron ore: ___","answers":[["sulphur","sulfur","s","phosphorus","p","arsenic","as"]],"mistakes":[{"id":"m1","blank":0,"answer":"iron"},{"id":"m2","blank":0,"answer":"oxygen"},{"id":"m3","blank":0,"answer":"silicon"}]},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Iron %","62","55"],["Harmful elements (S, P, As)","high","very low"]],"caption":"Made-up data for two ores","headers":["","Ore X","Ore Y"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tb","q","fb"]}}},"title":"Pick the better ore"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Iron: 4th most abundant in the crust, after O, Si and Al. It forms 5% by mass.","Pure iron metal (90%): only in meteorites. In the crust: ores, iron compounds (mostly oxides) mixed with impurities.","Ore suitability: iron %, composition of impurities, harmful elements (S, P, As)."]},"children":[]},"t":{"type":"Text","props":{"content":"Can you explain why an ore rich in iron might still be a poor choice?"},"children":[]},"x":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"Suitability is decided by three factors, not by the iron percentage alone: the composition of the impurities and the harmful elements mixed with the ore (sulphur, phosphorus, arsenic) count too."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","t","rv","x"]}}},"title":"Summary"}],"title":"Iron: abundance and suitability of iron ore","minutes":8,"book_ref":"Ch.1 'IRON', p.16","subtitle":"Where iron is found, and which ore is worth using","objectives":["State that iron is the fourth most abundant element in Earth's crust (5% by mass), after oxygen, silicon and aluminum.","State that pure iron metal (90%) is found only in meteorites; in the crust, iron is found as ores.","List the three factors that decide whether an iron ore is suitable for extracting iron."],"concept_ids":["fe.occurrence"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"How much we use shows demand, not how much there is in the crust: oxygen, silicon and aluminum are more abundant than iron."},{"id":"b","feedback":"Good guess. Iron is common, but it is not first."},{"id":"c","feedback":"Iron is not rare: it forms about 5% of the crust by mass."}],"explanation":"Iron is not the most abundant element in the crust: it is the fourth most abundant, after oxygen, silicon and aluminum, and forms about 5% of the crust by mass. Being the most used metal does not make it the most common."}},"s3":{"m":{"statement":"Iron is mined as pure metal.","correction":"Miners dig up ore. The iron must then be extracted from its compounds."}},"s4":{"o":{"items":[{"id":"o","feedback":"Oxygen is in rocks, sand and water alike."},{"id":"si","feedback":"Sand is silicon dioxide, so silicon is very common in the crust."},{"id":"al","feedback":"Two metals are in this list, and the book names aluminum before iron."},{"id":"fe","feedback":"Iron is the most important metal, but being important does not make it the most abundant."}],"explanation":"From most to least abundant in Earth's crust: oxygen, silicon, aluminum, then iron, the fourth most abundant element."}},"s5":{"m":{"statement":"Only the iron percentage matters when choosing an ore.","correction":"The composition of the impurities and the harmful elements count too."}},"s6":{"q":{"options":[{"id":"a","feedback":"Yes. Pure iron metal is found only in meteorites."},{"id":"b","feedback":"Ores in the crust hold iron compounds, mostly oxides, mixed with impurities, so an ore does not look like a lump of metal."},{"id":"c","feedback":"Iron in the crust is found combined in compounds, mostly oxides, not as lumps of metal."}],"explanation":"The lump most likely came from space as a meteorite: iron is found as pure metal (90%) in meteorites. In the crust, iron is found in ores, iron compounds (mostly oxides) mixed with impurities, not as lumps of metal."},"tf":{"explanation":"The statement is false: aluminum is more abundant than iron in Earth's crust. Iron is the most important metal in heavy industries, but it is the fourth most abundant element, after oxygen, silicon and aluminum.","feedback_true":"Importance is not abundance: in the crust ranking, aluminum, a metal, comes before iron.","feedback_false":"Right. Aluminum comes before iron in the crust."}},"s7":{"q":{"options":[{"id":"a","feedback":"That is the common trap: the iron percentage is one of three factors; the composition of the impurities and the harmful elements mixed with the ore also decide suitability."},{"id":"b","feedback":"Exactly. Ore X carries a lot of sulphur, phosphorus and arsenic. That counts against it."},{"id":"c","feedback":"There is no such rule: less iron is not a bonus. Suitability is decided by the iron percentage, the composition of the impurities and the harmful elements mixed with the ore."}],"explanation":"The best reply is that the iron percentage is not the only factor: the suitability of an ore also depends on the composition of its impurities and on the harmful elements mixed with it. Ore X has more iron, but it carries a lot of sulphur, phosphorus and arsenic."},"fb":{"mistakes":[{"id":"m1","feedback":"Iron is what we want to extract, not a harm. The book warns about non-metals mixed with the ore."},{"id":"m2","feedback":"Oxygen is part of the iron compounds themselves, not a harmful impurity mixed with the ore."},{"id":"m3","feedback":"Silicon is common in rocks, but it is not one of the harmful elements the book names."}],"explanation":"The book names sulphur, phosphorus and arsenic as harmful elements that can be mixed with an iron ore; any one of them answers the blank."}},"s8":{"x":{"body":"Common exam item: the three factors that decide the suitability of an iron ore."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"اللي بنستخدمه بيقول قد إيه إحنا محتاجينه، مش قد إيه موجود منه في القشرة الأرضية: الـ oxygen والـ silicon والـ aluminum أكتر وفرة من الـ iron."},{"id":"b","feedback":"تخمين حلو. الـ iron منتشر، لكنه مش الأول."},{"id":"c","feedback":"الـ iron مش نادر: بيكوّن حوالي 5% من القشرة الأرضية بالكتلة."}],"explanation":"الـ iron مش أكتر عنصر موجود في القشرة الأرضية: هو الرابع في الوفرة بعد الـ oxygen والـ silicon والـ aluminum، وبيكوّن حوالي 5% من القشرة الأرضية بالكتلة. وإنه أكتر metal بنستخدمه مش معناه إنه الأكتر انتشارًا."}},"s3":{"m":{"statement":"الـ iron بيطلع من المناجم metal نقي على طول.","correction":"اللي بيطلع من المناجم هو الـ ore. وبعدها لازم الـ iron يتستخلص من الـ compounds بتاعته."}},"s4":{"o":{"items":[{"id":"o","feedback":"الـ oxygen موجود في الصخور والرمل والمية كلهم."},{"id":"si","feedback":"الرمل ده silicon dioxide، والرمل والصخور منتشرين جدًا في القشرة الأرضية."},{"id":"al","feedback":"فيه اتنين metals في القايمة دي، والترتيب هنا بالوفرة في القشرة الأرضية زي ما الكتاب بيذكرها، مش بأهمية الـ metal ولا بشهرته."},{"id":"fe","feedback":"إن الـ iron أهم metal مش معناه إنه الأكتر وفرة في القشرة الأرضية."}],"explanation":"الترتيب من الأكتر للأقل وفرة في القشرة الأرضية: الـ oxygen، وبعده الـ silicon، وبعده الـ aluminum، وبعدهم الـ iron، الرابع في الوفرة."}},"s5":{"m":{"statement":"نسبة الـ iron هي الحاجة الوحيدة اللي تفرق في اختيار الـ ore.","correction":"تركيب الشوائب والعناصر الضارة بيتحسبوا هما كمان."}},"s6":{"q":{"options":[{"id":"a","feedback":"أيوه. الـ iron النقي على هيئة metal بيتلاقى في الـ meteorites تحديدًا."},{"id":"b","feedback":"الـ ores اللي في القشرة الأرضية فيها iron compounds، أغلبها oxides، مخلوطة بشوائب، فالـ ore مش بيبان كأنه حتة metal."},{"id":"c","feedback":"الـ iron في القشرة الأرضية موجود متحد في compounds، أغلبها oxides، مش على هيئة حتت metal."}],"explanation":"الحتة دي غالبًا جاية من الفضاء، يعني meteorite: الـ iron بيتلاقى على هيئة metal نقي (90%) في الـ meteorites. أما في القشرة الأرضية فالـ iron موجود في ores، يعني iron compounds (أغلبها oxides) مخلوطة بشوائب، مش حتت metal."},"tf":{"explanation":"الجملة دي false: الـ aluminum أكتر وفرة من الـ iron في القشرة الأرضية. الـ iron هو أهم metal في الصناعات التقيلة، لكنه رابع عنصر في الوفرة بعد الـ oxygen والـ silicon والـ aluminum.","feedback_true":"الأهمية حاجة والوفرة حاجة تانية: في ترتيب العناصر في القشرة الأرضية، الـ aluminum، وهو metal، بييجي قبل الـ iron.","feedback_false":"صح. الـ aluminum بييجي قبل الـ iron في القشرة الأرضية."}},"s7":{"q":{"options":[{"id":"a","feedback":"ده الفخ اللي ناس كتير بتقع فيه: نسبة الـ iron عامل واحد من تلات عوامل؛ تركيب الشوائب والعناصر الضارة المخلوطة بالـ ore كمان بيحددوا الصلاحية."},{"id":"b","feedback":"بالظبط. الـ Ore X فيه sulphur و phosphorus و arsenic كتير، وده بيتحسب ضده."},{"id":"c","feedback":"مفيش قاعدة زي كده: الـ iron الأقل مش ميزة. الصلاحية بتحددها نسبة الـ iron وتركيب الشوائب والعناصر الضارة المخلوطة بالـ ore."}],"explanation":"أحسن رد إن نسبة الـ iron مش العامل الوحيد: صلاحية الـ ore بتعتمد كمان على تركيب الشوائب اللي فيه وعلى العناصر الضارة المخلوطة بيه. الـ Ore X فيه iron أكتر، لكن فيه sulphur و phosphorus و arsenic كتير."},"fb":{"mistakes":[{"id":"m1","feedback":"الـ iron هو اللي إحنا عايزين نستخلصه، مش حاجة ضارة."},{"id":"m2","feedback":"الـ oxygen جزء من الـ iron compounds نفسها، مش عنصر ضار مخلوط بيها."},{"id":"m3","feedback":"الـ silicon منتشر في الصخور، لكن الكتاب مش بيذكره ضمن العناصر الضارة."}],"explanation":"الكتاب بيذكر الـ sulphur والـ phosphorus والـ arsenic كعناصر ضارة ممكن تكون مخلوطة بالـ iron ore؛ أي واحد فيهم يملا الفراغ."}},"s8":{"x":{"body":"سؤال بيتكرر في الامتحان: التلات عوامل اللي بيحددوا صلاحية الـ iron ore (suitability)."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":1,"lesson_no":8,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-extraction","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron ores and extraction of iron","duration_s":734.029,"start_s":22.1,"end_s":88.7,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.occurrence","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Iron: abundance and suitability of iron ore","duration_s":53.3,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron","section_title":"Iron","section_path":["Transition Elements","Iron"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.water-of-crystallization","kind":"lesson","version":2,"catalog_version":3,"ord":341,"primary_concept_id":"chem.water-of-crystallization","concepts":[{"concept_id":"chem.water-of-crystallization","role":"primary"}],"title":"Water of crystallization","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The crystals were wet on the outside","correct":false},{"id":"b","text":"Water was locked inside the crystals","correct":true},{"id":"c","text":"The heat made water from copper and sulphur","correct":false}],"question":"Predict: where did the water come from?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Heat dry blue copper(II) sulphate crystals in a test tube. They turn white. Water droplets collect near the cool top of the tube."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Dry crystals, wet tube"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{CuSO4.5H2O}","caption":"Blue copper(II) sulphate crystals"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Water of crystallization","definition":"A fixed number of water molecules held inside the crystal of a solid."},"children":[]},"t":{"type":"Text","props":{"content":"The dot joins the salt and its water. $\\ce{5H2O}$ means five water molecules for every one $\\ce{CuSO4}$."},"children":[]},"t2":{"type":"Text","props":{"content":"The number is fixed for each substance."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t","t2"]}}},"title":"The water in the formula"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{CuSO4.5H2O(s) ->[\\Delta] CuSO4(s) + 5H2O(v)}","caption":"Heating drives the water off as vapour"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Hydrated","definition":"Describes a substance that contains water of crystallization."},"children":[]},"t":{"type":"Text","props":{"content":"The blue hydrated crystals become a white powder. The solid left has lost all its water of crystallization."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t"]}}},"title":"Hydrated, then heated"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{2CaSO4.H2O}","caption":"Plaster of Paris"},"children":[]},"m":{"type":"Matching","props":{"pairs":[{"left":"$\\ce{Na2CO3.10H2O}$","right":"10 $\\ce{H2O}$ for every 1 $\\ce{Na2CO3}$"},{"left":"$\\ce{CoCl2.6H2O}$","right":"6 $\\ce{H2O}$ for every 1 $\\ce{CoCl2}$"},{"left":"$\\ce{CaSO4.2H2O}$","right":"2 $\\ce{H2O}$ for every 1 $\\ce{CaSO4}$"},{"left":"$\\ce{2CaSO4.H2O}$","right":"1 $\\ce{H2O}$ for every 2 $\\ce{CaSO4}$"}],"prompt":"Your turn: match each hydrate to the water it holds."},"children":[]},"t":{"type":"Text","props":{"content":"Sometimes a number stands in front of the first part too."},"children":[]},"t2":{"type":"Text","props":{"content":"Read it as: one $\\ce{H2O}$ for every two $\\ce{CaSO4}$. Each number counts the part right after it."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","f","t2","m"]}}},"title":"A number in front"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{Fe2O3}$","correct":false},{"id":"b","text":"$\\ce{Fe(OH)3}$","correct":false},{"id":"c","text":"$\\ce{FeSO4.7H2O}$","correct":true},{"id":"d","text":"$\\ce{FeCO3}$","correct":false}],"question":"Which of these iron compounds is hydrated?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"In $\\ce{2Fe2O3.3H2O}$, there are ___ water molecules for every ___ units of $\\ce{Fe2O3}$.","answers":[["3","three"],["2","two"]],"mistakes":[{"id":"m1","blank":0,"answer":"5"},{"id":"m2","blank":0,"answer":"6"},{"id":"m3","blank":1,"answer":"1"},{"id":"m4","blank":1,"answer":"4"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fb","q"]}}},"title":"Read these hydrates"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["**Water of crystallization**: a fixed number of water molecules inside a crystal.","It is written after a dot: $\\ce{CuSO4.5H2O}$. A number in front counts the part right after it.","**Hydrated** = contains water of crystallization. Heating drives this water off."]},"children":[]},"n":{"type":"Text","props":{"muted":true,"content":"Next: one iron ore, limonite, is a hydrated oxide."},"children":[]},"t":{"type":"Text","props":{"content":"Can you explain why heated blue crystals turn white and leave droplets?"},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"Heating drives the water of crystallization off as vapour: $\\ce{CuSO4.5H2O(s) ->[\\Delta] CuSO4(s) + 5H2O(v)}$. The white powder left has lost all its water, and the water collects as droplets near the cool top of the tube."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","t","rv","n"]}}},"title":"Summary"}],"title":"Water of crystallization","minutes":5,"book_ref":"Prerequisite (1st secondary chemistry); used in Ch.1 iron ores table, p.16 (limonite, hydrated iron III oxide, 2Fe2O3.3H2O)","subtitle":"Water locked inside crystals","objectives":["Explain that some crystals hold a fixed number of water molecules.","Read hydrate formulas written with a dot, including a number in front.","State that heating drives off the water of crystallization."],"concept_ids":["chem.water-of-crystallization"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"They looked and felt dry, and the colour changed too, which surface wetness would not explain."},{"id":"b","feedback":"Good thinking. The crystals held water inside them."},{"id":"c","feedback":"Water needs hydrogen atoms, and $\\ce{CuSO4}$ contains no hydrogen."}],"explanation":"The water was locked inside the crystals as water of crystallization. Heating drove it out, so the blue crystals turned white; it cannot come from copper and sulphur, because $\\ce{CuSO4}$ contains no hydrogen."}},"s4":{"m":{"explanation":"Each number counts the part right after it: $\\ce{Na2CO3.10H2O}$ has 10 $\\ce{H2O}$ for every 1 $\\ce{Na2CO3}$, $\\ce{CoCl2.6H2O}$ has 6 for every 1 $\\ce{CoCl2}$, $\\ce{CaSO4.2H2O}$ has 2 for every 1 $\\ce{CaSO4}$, and $\\ce{2CaSO4.H2O}$ has 1 $\\ce{H2O}$ for every 2 $\\ce{CaSO4}$."}},"s5":{"q":{"options":[{"id":"a","feedback":"There is no dot and no water part, so it has no water of crystallization."},{"id":"b","feedback":"It has H and O, but as OH groups, not water molecules, and there is no dot."},{"id":"c","feedback":"Yes: seven water molecules for every $\\ce{FeSO4}$."},{"id":"d","feedback":"It contains oxygen, but no $\\ce{H2O}$ part after a dot."}],"explanation":"$\\ce{FeSO4.7H2O}$ is the hydrated compound: after the dot it holds seven water molecules for every $\\ce{FeSO4}$. The others have no water part after a dot; $\\ce{Fe(OH)3}$ has H and O as OH groups, not water molecules."},"fb":{"mistakes":[{"id":"m1","feedback":"Five belongs to copper(II) sulphate; this formula's water part has its own number in front."},{"id":"m2","feedback":"6 is the number of H atoms, not of water molecules."},{"id":"m3","feedback":"The big number in front of the formula counts too: it multiplies the iron oxide part."},{"id":"m4","feedback":"4 counts Fe atoms, but the blank asks for units of $\\ce{Fe2O3}$."}],"explanation":"In $\\ce{2Fe2O3.3H2O}$ there are 3 water molecules for every 2 units of $\\ce{Fe2O3}$: the 3 counts the $\\ce{H2O}$ part and the 2 in front counts the $\\ce{Fe2O3}$ part."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ crystals كان شكلها وملمسها ناشف، وكمان لونها اتغيّر، وشوية بلل على السطح مايفسّروش ده."},{"id":"b","feedback":"تفكير حلو. الـ crystals كانت شايلة ميّة جواها."},{"id":"c","feedback":"الميّة محتاجة hydrogen atoms، والـ $\\ce{CuSO4}$ مفيهوش hydrogen."}],"explanation":"الميّة كانت محبوسة جوه الـ crystals على هيئة water of crystallization. التسخين طلّعها، عشان كده الـ crystals الزرقا بقت بيضا؛ ومينفعش تكون جاية من الـ copper والـ sulphur، لأن الـ $\\ce{CuSO4}$ مفيهوش hydrogen."}},"s4":{"m":{"explanation":"كل رقم بيعدّ الجزء اللي بعده على طول: الـ $\\ce{Na2CO3.10H2O}$ فيه 10 $\\ce{H2O}$ لكل 1 $\\ce{Na2CO3}$، والـ $\\ce{CoCl2.6H2O}$ فيه 6 لكل 1 $\\ce{CoCl2}$، والـ $\\ce{CaSO4.2H2O}$ فيه 2 لكل 1 $\\ce{CaSO4}$، والـ $\\ce{2CaSO4.H2O}$ فيه 1 $\\ce{H2O}$ لكل 2 $\\ce{CaSO4}$."}},"s5":{"q":{"options":[{"id":"a","feedback":"مفيش نقطة ومفيش جزء ميّة، فمفيهوش water of crystallization."},{"id":"b","feedback":"فيه H و O، لكن على هيئة OH groups، مش water molecules، ومفيش نقطة."},{"id":"c","feedback":"أيوه: سبعة water molecules لكل $\\ce{FeSO4}$."},{"id":"d","feedback":"فيه oxygen، لكن مفيش جزء ميّة ($\\ce{H2O}$) بعد نقطة."}],"explanation":"الـ $\\ce{FeSO4.7H2O}$ هو الـ hydrated compound: بعد النقطة فيه سبعة water molecules لكل $\\ce{FeSO4}$. الباقيين مفيهمش جزء ميّة بعد نقطة؛ والـ $\\ce{Fe(OH)3}$ فيه H و O على هيئة OH groups، مش water molecules."},"fb":{"mistakes":[{"id":"m1","feedback":"الخمسة دي بتاعة الـ copper(II) sulphate؛ جزء الميّة في الصيغة دي ليه رقمه الخاص اللي قدامه."},{"id":"m2","feedback":"الـ 6 دي عدد ذرات الـ H، مش عدد الـ water molecules."},{"id":"m3","feedback":"الرقم الكبير اللي قدام الصيغة بيتحسب هو كمان: هو بيضاعف جزء الـ iron oxide."},{"id":"m4","feedback":"الـ 4 دي عدد ذرات الـ Fe، لكن الفراغ بيسأل عن عدد وحدات الـ $\\ce{Fe2O3}$."}],"explanation":"في الـ $\\ce{2Fe2O3.3H2O}$ فيه 3 water molecules لكل 2 وحدة $\\ce{Fe2O3}$: الـ 3 بتعدّ جزء الـ $\\ce{H2O}$، والـ 2 اللي في الأول بتعدّ جزء الـ $\\ce{Fe2O3}$."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":2,"is_basics":true,"lesson_no":2,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-extraction","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron ores and extraction of iron","duration_s":734.029,"start_s":109,"end_s":131.9,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.water-of-crystallization","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Water of crystallization","duration_s":49.8,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":46,"page_to":47,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical 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x=\"230\" y=\"118\" text-anchor=\"middle\" font-size=\"13\" font-weight=\"500\" fill=\"#e2e8f0\">black</text><polygon points=\"350.6,60.0 343.3,79.5 326.0,93.9 304.4,87.0 289.6,71.1 290.9,49.4 303.7,31.7 325.3,29.9 342.0,41.5\" fill=\"#b8ad8c\" stroke=\"#e2e8f0\" stroke-width=\"1.5\"/><text x=\"320\" y=\"118\" text-anchor=\"middle\" font-size=\"13\" font-weight=\"500\" fill=\"#e2e8f0\">yellowish grey</text></svg>","max_width":380},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The blood-red ore","correct":false},{"id":"b","text":"The black ore","correct":true},{"id":"c","text":"The yellow ore","correct":false}],"question":"Predict: the four ores are crushed and mixed. A magnet passes over the pile. Which ore sticks to it?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Iron ores are not all the same. They come in different colours."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","t","q"]}}},"title":"Which one does the magnet pick?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"In iron III oxide, iron has oxidation state +3."},"children":[]},"t2":{"type":"Text","props":{"content":"\"Easily reduced\" means the oxide easily loses its oxygen to give iron."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Chemical name","Iron III oxide"],["Chemical formula","$\\ce{Fe2O3}$"],["Properties","Blood red colour; more easily reduced"],["Iron %","50-60"],["Place of deposits","Oasis area (Western Desert)"]],"headers":["Ore","Hematite"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tb","t","t2"]}}},"title":"1) Hematite"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Same iron III oxide as hematite, plus water of crystallization: 3 $\\ce{H2O}$ for every 2 $\\ce{Fe2O3}$."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Chemical name","Hydrated iron III oxide"],["Chemical formula","$\\ce{2Fe2O3.3H2O}$"],["Properties","Yellow hydrated oxide; easily reduced"],["Iron %","20-60"],["Place of deposits","Oasis area"]],"headers":["Ore","Limonite"]},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Limonite has no water in it."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tb","t","tf"]}}},"title":"2) Limonite"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"This is the ore the magnet picked out in the hook."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Chemical name","Magnetic iron oxide"],["Chemical formula","$\\ce{Fe3O4}$"],["Properties","Black ore having magnetic properties"],["Iron %","45-70"],["Place of deposits","Eastern Desert"]],"headers":["Ore","Magnetite"]},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Magnetite's formula is $\\ce{Fe2O3}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tb","t","tf"]}}},"title":"3) Magnetite"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Siderite is the odd one out: a **carbonate**, not an oxide. Here iron has oxidation state +2."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Chemical name","Iron II carbonate"],["Chemical formula","$\\ce{FeCO3}$"],["Properties","Yellowish grey colour; easily reduced"],["Iron %","30-42"],["Place of deposits","not given in the book"]],"headers":["Ore","Siderite"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tb","t"]}}},"title":"4) Siderite"},{"id":"s6","kind":"interact","spec":{"root":"root","elements":{"m":{"type":"Matching","props":{"pairs":[{"left":"Hematite","right":"$\\ce{Fe2O3}$"},{"left":"Limonite","right":"$\\ce{2Fe2O3.3H2O}$"},{"left":"Magnetite","right":"$\\ce{Fe3O4}$"},{"left":"Siderite","right":"$\\ce{FeCO3}$"}],"prompt":"Match each ore to its formula."},"children":[]},"ch":{"type":"Chart","props":{"kind":"bar","unit":"%","series":[{"name":"lowest","points":[{"x":"Hematite","y":50},{"x":"Limonite","y":20},{"x":"Magnetite","y":45},{"x":"Siderite","y":30}]},{"name":"highest","points":[{"x":"Hematite","y":60},{"x":"Limonite","y":60},{"x":"Magnetite","y":70},{"x":"Siderite","y":42}]}],"caption":"Iron % range of each ore (book table, p.16)","x_label":"Ore","y_label":"Iron %"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["ch","m"]}}},"title":"All four together"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{Fe2O3}$","correct":false},{"id":"b","text":"$\\ce{Fe3O4}$","correct":true},{"id":"c","text":"$\\ce{FeCO3}$","correct":false},{"id":"d","text":"$\\ce{2Fe2O3.3H2O}$","correct":false}],"question":"A geologist finds a black ore in the Eastern Desert. A magnet attracts it. What is its formula?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Siderite is an iron oxide, like the other three ores."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Identify the ore"},{"id":"s8","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"red","text":"Blood red colour"},{"id":"water","text":"Formula with a water part"},{"id":"yellow","text":"Yellow colour"},{"id":"grey","text":"Yellowish grey colour"},{"id":"east","text":"Found in the Eastern Desert"},{"id":"co3","text":"Contains the carbonate group"}],"answer":{"hem":["red"],"lim":["water","yellow"],"mag":["east"],"sid":["grey","co3"]},"prompt":"Sort each clue to its ore.","categories":[{"id":"hem","label":"Hematite"},{"id":"lim","label":"Limonite"},{"id":"mag","label":"Magnetite"},{"id":"sid","label":"Siderite"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c"]}}},"title":"Sort the clues"},{"id":"s9","kind":"recap","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Can you explain why siderite is the odd one out?"},"children":[]},"x":{"type":"Callout","props":{"variant":"exam"},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Hematite","$\\ce{Fe2O3}$","blood red; Oasis area (Western Desert)","50-60"],["Limonite","$\\ce{2Fe2O3.3H2O}$","yellow, hydrated; Oasis area","20-60"],["Magnetite","$\\ce{Fe3O4}$","black, magnetic; Eastern Desert","45-70"],["Siderite","$\\ce{FeCO3}$","yellowish grey, a carbonate","30-42"]],"headers":["Ore","Formula","Key clue","Iron %"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tb","t","x"]}}},"title":"Summary"}],"title":"Important iron ores","minutes":10,"book_ref":"Ch.1 'IRON', table of the most important iron ores, p.16","subtitle":"Hematite, limonite, magnetite and siderite","objectives":["Name the four important iron ores with their chemical names and formulas.","Match each ore with its colour, properties, iron % and place of deposits.","Tell the oxide ores (one hydrated, one magnetic) from the carbonate ore."],"concept_ids":["fe.ores"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"The blood-red ore (hematite) is not the one with magnetic properties: colour alone does not make a rock magnetic."},{"id":"b","feedback":"Good guess. The black ore has magnetic properties."},{"id":"c","feedback":"The yellow ore (limonite) is not the one with magnetic properties: colour alone does not make a rock magnetic."}],"explanation":"The black ore is magnetite, the ore with magnetic properties, so it sticks to the magnet. Colour alone does not make a rock magnetic: the blood-red and yellow ores do not have magnetic properties."}},"s3":{"tf":{"explanation":"Limonite does contain water: the $\\ce{.3H2O}$ in $\\ce{2Fe2O3.3H2O}$ is water of crystallization, so limonite is a hydrated iron III oxide.","feedback_true":"It does have water: the $\\ce{.3H2O}$ part of its formula shows that limonite is hydrated, with 3 $\\ce{H2O}$ for every 2 $\\ce{Fe2O3}$.","feedback_false":"Right. The $\\ce{.3H2O}$ part of $\\ce{2Fe2O3.3H2O}$ is water of crystallization, so limonite is a hydrated oxide."}},"s4":{"tf":{"explanation":"$\\ce{Fe2O3}$ is the formula of hematite. Magnetite, the magnetic iron oxide, is $\\ce{Fe3O4}$.","feedback_true":"That formula belongs to hematite. Magnetite, the magnetic one, has more atoms: $\\ce{Fe3O4}$.","feedback_false":"Right. $\\ce{Fe2O3}$ is hematite; magnetite, the magnetic one, has more atoms: $\\ce{Fe3O4}$."}},"s6":{"m":{"explanation":"Hematite is iron III oxide, $\\ce{Fe2O3}$; limonite is the same oxide hydrated, $\\ce{2Fe2O3.3H2O}$; magnetite is $\\ce{Fe3O4}$; siderite is the carbonate, $\\ce{FeCO3}$."}},"s7":{"q":{"options":[{"id":"a","feedback":"$\\ce{Fe2O3}$ is hematite: a blood-red ore from the Oasis area, not a black ore from the Eastern Desert."},{"id":"b","feedback":"Yes: magnetite, magnetic iron oxide."},{"id":"c","feedback":"$\\ce{FeCO3}$ is siderite, iron II carbonate: a yellowish grey ore, not a black one."},{"id":"d","feedback":"$\\ce{2Fe2O3.3H2O}$ is limonite: a yellow hydrated oxide from the Oasis area, not a black ore."}],"explanation":"A black ore from the Eastern Desert that a magnet attracts is magnetite, magnetic iron oxide: $\\ce{Fe3O4}$. Hematite ($\\ce{Fe2O3}$) is blood red, limonite ($\\ce{2Fe2O3.3H2O}$) is yellow and siderite ($\\ce{FeCO3}$) is yellowish grey."},"tf":{"explanation":"Of the four ores, siderite is the carbonate one: its formula, $\\ce{FeCO3}$, contains the carbonate group $\\ce{CO3}$.","feedback_true":"Siderite's formula, $\\ce{FeCO3}$, has the carbonate group after Fe, not oxygen alone: it is iron II carbonate, not an oxide.","feedback_false":"Right: siderite is iron II carbonate."}},"s8":{"c":{"items":[{"id":"red","feedback":"Red points to the plain iron III oxide, which is not hydrated."},{"id":"water","feedback":"A water part means hydrated, and only one ore in the table is the hydrated oxide."},{"id":"yellow","feedback":"Yellow and yellowish grey are two different ores, and the yellow one is the ore that holds water."},{"id":"grey","feedback":"Yellowish grey is not plain yellow: it is the colour of the carbonate ore."},{"id":"east","feedback":"Only one ore in the table comes from the Eastern Desert, so this clue matches that ore alone."},{"id":"co3","feedback":"Three of the ores are oxides; only one is a carbonate."}],"explanation":"Blood red points to hematite. A water part and a yellow colour point to limonite, the hydrated oxide. The Eastern Desert points to magnetite. Yellowish grey and the carbonate group point to siderite."}},"s9":{"x":{"body":"Common exam item: the formula and chemical name of each ore, and which one is magnetic or hydrated."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ ore الأحمر الدموي (الـ hematite) مش هو اللي عنده خواص مغناطيسية: اللون لوحده مش بيخلّي الصخرة مغناطيسية."},{"id":"b","feedback":"تخمين حلو. الـ ore الأسود ده عنده خواص مغناطيسية."},{"id":"c","feedback":"الـ ore الأصفر (الـ limonite) مش هو اللي عنده خواص مغناطيسية: اللون لوحده مش بيخلّي الصخرة مغناطيسية."}],"explanation":"الـ ore الأسود هو الـ magnetite، الـ ore اللي عنده خواص مغناطيسية، فهو اللي بيلزق في الـ magnet. واللون لوحده مش بيخلّي الصخرة مغناطيسية: الـ ore الأحمر الدموي والأصفر مالهمش خواص مغناطيسية."}},"s3":{"tf":{"explanation":"الـ limonite فيه مية: الـ $\\ce{.3H2O}$ اللي في $\\ce{2Fe2O3.3H2O}$ ده water of crystallization، عشان كده الـ limonite يبقى hydrated iron III oxide.","feedback_true":"لأ، فيه مية: الجزء $\\ce{.3H2O}$ في الـ formula بتاعته بيوضّح إن الـ limonite متميّه (hydrated)، فيه 3 $\\ce{H2O}$ لكل 2 $\\ce{Fe2O3}$.","feedback_false":"صح. الجزء $\\ce{.3H2O}$ اللي في $\\ce{2Fe2O3.3H2O}$ ده water of crystallization، عشان كده الـ limonite يبقى hydrated oxide."}},"s4":{"tf":{"explanation":"$\\ce{Fe2O3}$ دي الـ formula بتاعة الـ hematite. أما الـ magnetite، الـ magnetic iron oxide، فهو $\\ce{Fe3O4}$.","feedback_true":"الـ formula دي بتاعة الـ hematite. الـ magnetite، اللي هو المغناطيسي، ذراته أكتر: $\\ce{Fe3O4}$.","feedback_false":"صح. $\\ce{Fe2O3}$ ده الـ hematite؛ إنما الـ magnetite، اللي هو المغناطيسي، ذراته أكتر: $\\ce{Fe3O4}$."}},"s6":{"m":{"explanation":"الـ hematite هو iron III oxide، $\\ce{Fe2O3}$؛ والـ limonite هو نفس الـ oxide لكن hydrated، $\\ce{2Fe2O3.3H2O}$؛ والـ magnetite هو $\\ce{Fe3O4}$؛ والـ siderite هو الـ carbonate، $\\ce{FeCO3}$."}},"s7":{"q":{"options":[{"id":"a","feedback":"$\\ce{Fe2O3}$ ده الـ hematite: ore لونه أحمر دموي من منطقة الواحات، مش ore أسود من الصحرا الشرقية."},{"id":"b","feedback":"أيوه: ده الـ magnetite، يعني الـ magnetic iron oxide."},{"id":"c","feedback":"$\\ce{FeCO3}$ ده الـ siderite، يعني iron II carbonate: ore لونه رمادي مصفرّ، مش أسود."},{"id":"d","feedback":"$\\ce{2Fe2O3.3H2O}$ ده الـ limonite: hydrated oxide لونه أصفر من منطقة الواحات، مش ore أسود."}],"explanation":"ore أسود من الصحرا الشرقية والـ magnet بيجذبه يبقى الـ magnetite، يعني الـ magnetic iron oxide: $\\ce{Fe3O4}$. الـ hematite ($\\ce{Fe2O3}$) لونه أحمر دموي، والـ limonite ($\\ce{2Fe2O3.3H2O}$) أصفر، والـ siderite ($\\ce{FeCO3}$) رمادي مصفرّ."},"tf":{"explanation":"من الأربع ores، الـ siderite هو الـ carbonate: الـ formula بتاعته $\\ce{FeCO3}$ فيها الـ carbonate group $\\ce{CO3}$.","feedback_true":"الـ formula بتاعة الـ siderite، $\\ce{FeCO3}$، فيها بعد الـ Fe الـ carbonate group، مش oxygen لوحده: يعني هو iron II carbonate، مش oxide.","feedback_false":"صح: الـ siderite هو iron II carbonate."}},"s8":{"c":{"items":[{"id":"red","feedback":"الأحمر الدموي بيشاور على الـ iron III oxide العادي، اللي مش hydrated."},{"id":"water","feedback":"وجود جزء مية في الـ formula معناه إن الـ ore ده hydrated، وده بيشاور على الـ hydrated oxide اللي في الجدول."},{"id":"yellow","feedback":"الأصفر والرمادي المصفرّ دول لونين لـ 2 ores مختلفين، والأصفر هو لون الـ ore اللي فيه مية."},{"id":"grey","feedback":"الرمادي المصفرّ مش هو الأصفر العادي، وده لون الـ ore اللي فيه الـ carbonate group."},{"id":"east","feedback":"مفيش غير ore واحد في الجدول جاي من الصحرا الشرقية، والخانة اللي اخترتها مش بتاعته."},{"id":"co3","feedback":"تلات ores من الأربعة oxides، والـ carbonate group موجودة في الـ ore الرابع اللي مش oxide."}],"explanation":"اللون الأحمر الدموي بيشاور على الـ hematite. جزء المية في الـ formula واللون الأصفر بيشاوروا على الـ limonite، الـ hydrated oxide. الصحرا الشرقية بتشاور على الـ magnetite. واللون الرمادي المصفرّ والـ carbonate group بيشاوروا على الـ siderite."}},"s9":{"x":{"body":"سؤال بييجي كتير في الامتحان: الـ formula والـ chemical name لكل ore، ومين فيهم اللي magnetic ومين اللي hydrated."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":2,"lesson_no":9,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-extraction","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron ores and extraction of iron","duration_s":734.029,"start_s":94.3,"end_s":160.8,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.ores","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Important iron ores","duration_s":51.83,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.mixture-separation","kind":"lesson","version":2,"catalog_version":1,"ord":345,"primary_concept_id":"chem.mixture-separation","concepts":[{"concept_id":"chem.mixture-separation","role":"primary"}],"title":"Separating mixtures","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Shake the mixture through a sieve","correct":false},{"id":"b","text":"Pass a magnet over the mixture","correct":true},{"id":"c","text":"Add water and stir until both dissolve","correct":false}],"question":"Predict: what is the quickest way to separate them?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Iron filings got mixed into dry sand. The grains are about the same size."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Filings in the sand"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 30 345 195\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><line x1=\"20\" y1=\"80\" x2=\"230\" y2=\"80\" stroke=\"#e2e8f0\" stroke-width=\"3\"/><circle cx=\"30\" cy=\"92\" r=\"12\" fill=\"none\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"240\" cy=\"92\" r=\"20\" fill=\"#f87171\" fill-opacity=\"0.25\" stroke=\"#f87171\" stroke-width=\"2.5\"/><text x=\"240\" y=\"50\" text-anchor=\"middle\" font-size=\"13\" font-weight=\"700\" fill=\"#f87171\">magnetic drum</text><line x1=\"240.0\" y1=\"56.0\" x2=\"240.0\" y2=\"68.0\" stroke=\"#f87171\" stroke-width=\"1.5\" stroke-linecap=\"round\"/><polygon points=\"240.0,68.0 237.4,62.6 242.6,62.6\" fill=\"#f87171\"/><circle cx=\"50\" cy=\"71.8\" r=\"5\" fill=\"#334155\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"65\" cy=\"71.5\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"80\" cy=\"71.4\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"95\" cy=\"71.1\" r=\"5\" fill=\"#334155\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"110\" cy=\"71.5\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"125\" cy=\"71.2\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"140\" cy=\"72.9\" r=\"5\" fill=\"#334155\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"155\" cy=\"72.1\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"170\" cy=\"71.1\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"185\" cy=\"71.7\" r=\"5\" fill=\"#334155\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"200\" cy=\"71.2\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"215\" cy=\"72.8\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"272\" cy=\"100\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"282\" cy=\"125\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"290\" cy=\"150\" r=\"5\" fill=\"#d6c49a\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"252\" cy=\"110\" r=\"5\" fill=\"#334155\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"238\" cy=\"114\" r=\"5\" fill=\"#334155\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><circle cx=\"230\" cy=\"140\" r=\"5\" fill=\"#334155\" stroke=\"#e2e8f0\" stroke-width=\"0.8\"/><path d=\"M200,165 L205,195 L255,195 L260,165\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><path d=\"M270,165 L275,195 L325,195 L330,165\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2\"/><text x=\"230\" y=\"214\" text-anchor=\"middle\" font-size=\"13\" font-weight=\"500\" fill=\"#e2e8f0\">attracted</text><text x=\"300\" y=\"214\" text-anchor=\"middle\" font-size=\"13\" font-weight=\"500\" fill=\"#e2e8f0\">not attracted</text><line x1=\"60.0\" y1=\"104.0\" x2=\"140.0\" y2=\"104.0\" stroke=\"#94a3b8\" stroke-width=\"1.5\" stroke-linecap=\"round\"/><polygon points=\"140.0,104.0 133.7,107.0 133.7,101.0\" fill=\"#94a3b8\"/><text x=\"100\" y=\"122\" text-anchor=\"middle\" font-size=\"12\" font-weight=\"500\" fill=\"#94a3b8\">conveyor belt</text></svg>","max_width":380},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Magnetic separation","definition":"A magnet attracts the particles that are magnetic. 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The water's surface holds up one kind of particle while the other sinks, so the two come apart."},{"id":"c","feedback":"That would make a new substance, while separating a mixture keeps each part as it is."}],"explanation":"The difference given is how the powders behave on water: surface tension holds up particles of one powder while the other sinks, so separation by surface tension works. No new substance forms."},"tf":{"explanation":"Separating a mixture forms no new substance: after the magnet separates them, the filings are still iron, still grey and still attracted by the magnet.","feedback_true":"The filings are still grey and still attracted by the magnet afterwards: no new substance forms when a mixture is separated.","feedback_false":"Right. Separating a mixture forms no new substance."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"المنخل بيفرز على حسب الحجم، والحبيبات هنا تقريبًا في نفس الحجم، فالمنخل مش هيقدر يفصلهم."},{"id":"b","feedback":"حلو. الـ magnet بيجذب الـ iron، لكن مش بيجذب الرمل."},{"id":"c","feedback":"لا الـ iron ولا الرمل بيدوبوا في الميّة، فتقليبهم في الميّة مش هيفصلهم."}],"explanation":"الـ magnet بيجذب الـ iron ومش بيجذب الرمل. الحبيبات تقريبًا في نفس الحجم ومفيش حاجة فيهم بتدوب في الميّة، فالمنخل أو الميّة مش هيفصلوهم."}},"s4":{"m":{"explanation":"كل طريقة بتستغل خاصية واحدة مش مشتركة بين الأجزاء: الـ magnet بيجذب الحبيبات المغناطيسية، وسطح الميّة بيشيل شوية حبيبات صغيرة، والـ charged plate بيجذب الحبيبات اللي بتاخد charge أسهل."}},"s5":{"q":{"options":[{"id":"a","feedback":"السؤال ماقالش إن أي مسحوق فيهم بيتجذب للـ magnet؛ الفرق اللي إداهولك هو تصرّف المسحوقين على سطح الميّة."},{"id":"b","feedback":"أيوه. سطح الميّة بيشيل نوع من الحبيبات والنوع التاني بيغطس، فالاتنين بينفصلوا."},{"id":"c","feedback":"كده هتعمل مادة جديدة، وفصل الـ mixture بيسيب كل جزء زي ما هو."}],"explanation":"الفرق اللي في السؤال هو تصرّف المسحوقين على الميّة: الـ surface tension بيشيل حبيبات مسحوق واحد والتاني بيغطس، فالفصل بالـ surface tension هو اللي ينفع. ومفيش مادة جديدة بتتكوّن."},"tf":{"explanation":"فصل الـ mixture مابيكوّنش مادة جديدة: بعد ما الـ magnet يفصلهم، البرادة لسه iron، ولسه لونها رمادي، ولسه الـ magnet بيجذبها.","feedback_true":"البرادة بعد الفصل لسه لونها رمادي ولسه الـ magnet بيجذبها: فصل الـ mixture مابيكوّنش مادة جديدة.","feedback_false":"صح. فصل الـ mixture مابيكوّنش مادة جديدة."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":3,"is_basics":true,"lesson_no":3,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-chem.mixture-separation","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Separating mixtures: from zero","duration_s":320.5,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.mixture-separation","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Separating mixtures","duration_s":47.24,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.lesson-fe.ore-dressing","kind":"lesson","version":4,"catalog_version":3,"ord":347,"primary_concept_id":"fe.ore-dressing","concepts":[{"concept_id":"fe.ore-dressing","role":"primary"}],"title":"Ore dressing: crushing, sintering, concentrating","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"To get pieces of a suitable size, so the ore is easily reduced","correct":true},{"id":"b","text":"Crushing turns the iron oxide into iron","correct":false},{"id":"c","text":"Crushing removes all the impurities","correct":false}],"question":"Predict: why are the rocks crushed first?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Ore comes out of the mine as big rocks, mixed with impurities. 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Which process fixes it?","categories":[{"id":"cr","label":"Crushing"},{"id":"si","label":"Sintering"},{"id":"co","label":"Concentrating"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c"]}}},"title":"Which process?"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Magnetic separation","correct":true},{"id":"b","text":"Sintering","correct":false},{"id":"c","text":"Melting the ore","correct":false}],"question":"Crushed magnetite ore is mixed with sand. 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Mixed impurities go by surface tension, magnetic or electric separation."]},"children":[]},"t":{"type":"Text","props":{"content":"Can you explain why both crushing and sintering are needed?"},"children":[]},"x":{"type":"Callout","props":{"variant":"exam"},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Crushing","Big rocks","A suitable size, easily reduced"],["Sintering","Fine particles from crushing and cleaning the furnace","Larger, similar, homogeneous lumps"],["Concentrating","Impurities chemically combined or mixed with the ore","A higher iron %"]],"caption":"Part 1 of ore dressing; roasting (part 2) comes next","headers":["Process","Problem it fixes","Result"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tab","t","x"]}}},"title":"Summary"}],"title":"Ore dressing: crushing, sintering, concentrating","minutes":9,"book_ref":"Ch.1 'Extraction of Iron from its Ores', Firstly: Ore dressing, 1- a, b, c, p.17","subtitle":"Getting the ore ready for the furnace","objectives":["State that ore dressing improves the ore's physical and mechanical properties (and its chemical properties).","Give the purpose of crushing, sintering and concentrating.","Explain that impurities mixed with the ore are separated by surface tension, magnetic or electric separation."],"concept_ids":["fe.ore-dressing"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. The size of the pieces matters for reduction."},{"id":"b","feedback":"Crushing breaks rock into smaller pieces; breaking a rock does not remove oxygen from the oxide."},{"id":"c","feedback":"Smaller pieces still carry the same impurities; breaking them does not remove the impurities."}],"explanation":"Crushing breaks the rocks into pieces of a suitable size, so the ore is easily reduced. Breaking the rock does not remove the impurities or turn the iron oxide into iron."}},"s3":{"w":{"body":"But crushing also makes very fine particles. Too fine is a problem too: see the next step."}},"s4":{"tf":{"explanation":"Sintering collects the fine ore particles into larger lumps that are similar and homogeneous; the ore is not melted.","feedback_true":"No. Sintering gathers the fine particles into larger lumps; the ore is not turned into a liquid.","feedback_false":"Right. Sintering collects the fine particles into larger, similar and homogeneous lumps; the ore is not melted."}},"s6":{"c":{"items":[{"id":"rocks","feedback":"The pieces are too big, so they need breaking into smaller pieces."},{"id":"dust","feedback":"Too small to use directly, so these need joining into larger lumps."},{"id":"fines","feedback":"Too small for the furnace, so these need joining into larger lumps."},{"id":"sand","feedback":"The size is fine here; the problem is the sand mixed in with the ore."}],"explanation":"Big rocks need crushing to a suitable size. Fine dust from cleaning the furnace and fine particles from crushing need sintering into larger lumps. Ore with sand mixed in needs concentrating to remove the impurities."}},"s7":{"q":{"options":[{"id":"a","feedback":"Yes. Magnetite has magnetic properties; sand does not."},{"id":"b","feedback":"Sintering gathers fine particles into lumps; it does not remove the sand."},{"id":"c","feedback":"Melting does not sort the sand out of the ore."}],"explanation":"Magnetite has magnetic properties and sand does not, so magnetic separation removes the mixed sand and concentrates the ore. Sintering joins fine particles into lumps without removing the sand, and melting does not sort the sand out."},"tf":{"explanation":"The iron oxide itself does not change: the impurities mixed with the ore are separated physically.","feedback_true":"The magnet only moves the grains: the magnetite is still magnetite afterwards.","feedback_false":"Right. Separating the mixed impurities is a physical process."}},"s8":{"x":{"body":"Give reasons: sintering is needed. Fine particles from crushing and furnace cleaning cannot be used directly in the blast furnace."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. حجم الحتت ليه دور مهم في الـ reduction."},{"id":"b","feedback":"الـ crushing بيكسّر الصخر لحتت أصغر؛ وتكسير الصخرة مش بيشيل الـ oxygen من الـ oxide."},{"id":"c","feedback":"الحتت الصغيرة لسه فيها نفس الشوائب؛ تكسيرها مش بيشيل الشوائب."}],"explanation":"الـ crushing بيكسّر الصخور لحتت بحجم مناسب، عشان الـ ore يتختزل بسهولة. وتكسير الصخرة مش بيشيل الشوائب ولا بيحوّل الـ iron oxide لـ iron."}},"s3":{"w":{"body":"لكن خلّي بالك: الـ crushing كمان بيطلّع حبيبات ناعمة جدًا. والنعومة الزيادة دي مشكلة هي كمان، وده اللي هتشوفه في الخطوة الجاية."}},"s4":{"tf":{"explanation":"الـ sintering بيجمّع حبيبات الـ ore الناعمة في كتل أكبر متشابهة ومتجانسة؛ الـ ore مش بيسيح.","feedback_true":"لأ. الـ sintering بيلمّ الحبيبات الناعمة في كتل أكبر؛ الـ ore مش بيتحوّل لسائل.","feedback_false":"صح. الـ sintering بيجمّع الحبيبات الناعمة في كتل أكبر متشابهة ومتجانسة؛ الـ ore مش بيسيح."}},"s6":{"c":{"items":[{"id":"rocks","feedback":"الحتت كبيرة زيادة عن إنها تتختزل بسهولة: المشكلة هنا في الحجم الكبير، مش في الشوائب."},{"id":"dust","feedback":"صغيرة زيادة عن إنها تتستخدم على طول: المشكلة هنا في الحجم الصغير، مش في الشوائب."},{"id":"fines","feedback":"الحبيبات دي صغيرة على الفرن، وتكسيرها تاني هيصغّرها أكتر."},{"id":"sand","feedback":"الحجم هنا تمام؛ المشكلة إن فيه رمل كتير مخلوط بالـ ore، يعني شوائب."}],"explanation":"الصخور الكبيرة محتاجة crushing لحجم مناسب. التراب الناعم من تنضيف الفرن والحبيبات الناعمة اللي فاضلة من الـ crushing محتاجين sintering عشان يتجمّعوا في كتل أكبر. والـ ore اللي مخلوط بيه رمل محتاج concentrating عشان الشوائب تتشال."}},"s7":{"q":{"options":[{"id":"a","feedback":"أيوه. الـ magnetite ليه خواص مغناطيسية، والرمل لأ."},{"id":"b","feedback":"الـ sintering بيلمّ الحبيبات الناعمة في كتل؛ مش بيشيل الرمل."},{"id":"c","feedback":"الصهر مش هيفصل الرمل عن الـ ore."}],"explanation":"الـ magnetite ليه خواص مغناطيسية والرمل لأ، فالـ magnetic separation بيشيل الرمل المخلوط ويركّز الـ ore. الـ sintering بيجمّع الحبيبات الناعمة في كتل من غير ما يشيل الرمل، والصهر مش بيفصل الرمل."},"tf":{"explanation":"الـ iron oxide نفسه مابيتغيّرش: الشوائب المخلوطة بالـ ore بتتفصل بطريقة فيزيائية.","feedback_true":"المغناطيس مجرد بيحرّك الحبيبات: الـ magnetite بيفضل magnetite بعدها.","feedback_false":"صح. فصل الشوائب المخلوطة ده عملية فيزيائية."}},"s8":{"x":{"body":"علّل (Give reasons): الـ sintering مهم. لأن الحبيبات الناعمة اللي بتطلع من الـ crushing ومن تنضيف الفرن مينفعش تتحط في الـ blast furnace على طول."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":3,"lesson_no":10,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-extraction","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron ores and extraction of iron","duration_s":734.029,"start_s":167.8,"end_s":236.3,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.ore-dressing","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Ore dressing: crushing, sintering, concentrating","duration_s":55.35,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.reaction-types","kind":"lesson","version":2,"catalog_version":3,"ord":349,"primary_concept_id":"chem.reaction-types","concepts":[{"concept_id":"chem.reaction-types","role":"primary"}],"title":"Types of chemical reactions","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It broke down into two simpler substances","correct":true},{"id":"b","text":"It just melted","correct":false},{"id":"c","text":"It took in a gas from the air","correct":false}],"question":"Predict: what happened to the green solid?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Heat green copper(II) carbonate. It turns into a black powder, and a gas comes off."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Green to black"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{CuCO3(s) ->[\\Delta] CuO(s) + CO2(g)}","caption":"green solid → black solid + gas"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Thermal decomposition","definition":"Breaking down a compound by heat into simpler substances."},"children":[]},"t":{"type":"Text","props":{"content":"Pattern: one compound in, two or more substances out. The $\\Delta$ over the arrow means heat."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t"]}}},"title":"Thermal decomposition"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{Zn(s) + CuSO4(aq) -> ZnSO4(aq) + Cu(s)}","caption":"Zinc is above copper in the activity series."},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Simple displacement","definition":"A more active element takes the place of a less active one in its compound."},"children":[]},"t":{"type":"Text","props":{"content":"The blue colour fades, and reddish copper coats the zinc."},"children":[]},"t2":{"type":"Text","props":{"content":"Metals above hydrogen also displace it from dilute acids: $\\ce{Mg + 2HCl -> MgCl2 + H2}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t","t2"]}}},"title":"Simple displacement"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{AgNO3(aq) + NaCl(aq) -> AgCl(s) v + NaNO3(aq)}","caption":"A white solid appears in the solution."},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Double displacement","definition":"Two compounds exchange their partners: AB + CD → AD + CB."},"children":[]},"r":{"type":"Reveal","props":{"label":"Another double displacement you know"},"children":["f2"]},"t":{"type":"Text","props":{"content":"AgCl does not dissolve, so it separates as a solid. Such a solid is a **precipitate**, shown by ↓."},"children":[]},"f2":{"type":"Formula","props":{"latex":"\\ce{NaOH + HCl -> NaCl + H2O}","caption":"acid + base → salt + water"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t","r"]}}},"title":"Double displacement"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"caco3","text":"$\\ce{CaCO3 ->[\\Delta] CaO + CO2}$"},{"id":"znoh","text":"$\\ce{Zn(OH)2 ->[\\Delta] ZnO + H2O}$"},{"id":"zn","text":"$\\ce{Zn + H2SO4 -> ZnSO4 + H2}$"},{"id":"fe","text":"$\\ce{Fe + CuSO4 -> FeSO4 + Cu}$"},{"id":"ba","text":"$\\ce{BaCl2 + Na2SO4 -> BaSO4 v + 2NaCl}$"},{"id":"koh","text":"$\\ce{KOH + HNO3 -> KNO3 + H2O}$"}],"answer":{"dd":["ba","koh"],"sd":["zn","fe"],"td":["caco3","znoh"]},"prompt":"Sort each reaction by its type.","categories":[{"id":"td","label":"Thermal decomposition"},{"id":"sd","label":"Simple displacement"},{"id":"dd","label":"Double displacement"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A gas leaves the reaction","correct":false},{"id":"b","text":"An insoluble solid forms in the solution","correct":true},{"id":"c","text":"The reaction needs heat","correct":false}],"question":"In $\\ce{CuSO4 + 2NaOH -> Cu(OH)2 v + Na2SO4}$, what does ↓ after $\\ce{Cu(OH)2}$ tell you?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Spot the type"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["**Thermal decomposition**: heat breaks one compound into simpler substances.","**Simple displacement**: a more active element replaces a less active one.","**Double displacement**: two compounds swap partners. A precipitate (↓) or salt + water may form."]},"children":[]},"n":{"type":"Text","props":{"muted":true,"content":"Next: roasting heats iron ores, and some of its changes are thermal decompositions."},"children":[]},"t":{"type":"Text","props":{"content":"Can you explain how to tell simple from double displacement at a glance?"},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_tb"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","t","ans","n"]},"ans_tb":{"type":"DataTable","props":{"rows":[["Simple displacement","A more active element takes the place of a less active one in its compound.","$\\ce{Zn + CuSO4 -> ZnSO4 + Cu}$"],["Double displacement","Two compounds exchange their partners: AB + CD → AD + CB.","$\\ce{AgNO3 + NaCl -> AgCl v + NaNO3}$"]],"headers":["Type","What happens","Example"]},"children":[]}}},"title":"Summary"}],"title":"Types of chemical reactions","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 roasting, p.17 (thermal decomposition) and iron oxides, p.22-23 (heating, precipitation)","subtitle":"Break down, swap one, swap two","objectives":["Recognize thermal decomposition, simple displacement and double displacement from their equations.","Explain what the ↓ sign after a product means (a precipitate)."],"concept_ids":["chem.reaction-types"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. Heat split it into a black solid and a gas."},{"id":"b","feedback":"Melting keeps the same substance, and it would not give a gas and a new colour."},{"id":"c","feedback":"Then gas would go into the solid, but here gas is leaving the solid."}],"explanation":"The green copper(II) carbonate broke down into two simpler substances: heat split it into a black solid and a gas. Melting would keep the same substance, and here a gas comes out of the solid instead of going in."}},"s5":{"c":{"items":[{"id":"caco3","feedback":"One compound turned into two substances by heat, and nothing swapped places."},{"id":"znoh","feedback":"Only one reactant, plus heat: one compound broke down."},{"id":"zn","feedback":"A lone element went in and a different lone element came out, with one compound reacting."},{"id":"fe","feedback":"Iron went in alone and copper came out alone: one element took the place of another."},{"id":"ba","feedback":"Two compounds went in and two came out: the partners swapped, and no element pushed another out."},{"id":"koh","feedback":"An acid and a base gave a salt and water: the two compounds exchanged partners."}],"explanation":"Thermal decomposition: one compound breaks down by heat ($\\ce{CaCO3}$, $\\ce{Zn(OH)2}$). Simple displacement: an element takes the place of another element in a compound ($\\ce{Zn + H2SO4}$, $\\ce{Fe + CuSO4}$). Double displacement: two compounds exchange partners ($\\ce{BaCl2 + Na2SO4}$, $\\ce{KOH + HNO3}$)."},"q":{"options":[{"id":"a","feedback":"A gas leaving is shown by an up arrow, ↑, and this arrow points down."},{"id":"b","feedback":"Yes: $\\ce{Cu(OH)2}$ is a precipitate."},{"id":"c","feedback":"Heat is written as $\\Delta$ over the arrow, not as a down arrow after a product."}],"explanation":"The down arrow ↓ after $\\ce{Cu(OH)2}$ means it is a precipitate: an insoluble solid that forms in the solution. A gas leaving is shown by ↑, and heat by $\\Delta$ over the arrow."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. الحرارة كسّرته لـ solid أسود و gas."},{"id":"b","feedback":"الانصهار بيسيب المادة زي ما هي، ومش بيطلّع gas ولا لون جديد."},{"id":"c","feedback":"لو كده، كان الـ gas هيدخل في الـ solid، لكن هنا الـ gas خارج من الـ solid."}],"explanation":"الـ copper(II) carbonate الأخضر اتكسّر لمادتين أبسط: الحرارة فصلته لـ solid أسود و gas. الانصهار كان هيسيب المادة زي ما هي، وهنا الـ gas خارج من الـ solid مش داخل فيه."}},"s5":{"c":{"items":[{"id":"caco3","feedback":"compound واحد اتحوّل لمادتين بالحرارة، ومفيش حاجة بدّلت مكانها."},{"id":"znoh","feedback":"مفيش غير reactant واحد ومعاه حرارة: compound واحد اتكسّر."},{"id":"zn","feedback":"دخل element لوحده وطلع element تاني مختلف لوحده، وكان فيه compound واحد اتفاعل."},{"id":"fe","feedback":"الـ iron دخل لوحده والـ copper طلع لوحده: element واحد أخد مكان element تاني."},{"id":"ba","feedback":"دخل 2 compounds وطلع 2: الشُّركا اتبادلوا، ومفيش element زقّ element تاني وطلّعه."},{"id":"koh","feedback":"acid و base إدّوا salt وميّة: الـ 2 compounds بدّلوا الشُّركا."}],"explanation":"الـ thermal decomposition: compound واحد بيتكسّر بالحرارة ($\\ce{CaCO3}$ و $\\ce{Zn(OH)2}$). الـ simple displacement: element بياخد مكان element تاني في compound ($\\ce{Zn + H2SO4}$ و $\\ce{Fe + CuSO4}$). الـ double displacement: 2 compounds بيتبادلوا الشُّركا ($\\ce{BaCl2 + Na2SO4}$ و $\\ce{KOH + HNO3}$)."},"q":{"options":[{"id":"a","feedback":"خروج gas بيتكتب بسهم لفوق ↑، والسهم ده اتجاهه لتحت."},{"id":"b","feedback":"أيوه: الـ $\\ce{Cu(OH)2}$ ده precipitate."},{"id":"c","feedback":"الحرارة بتتكتب $\\Delta$ فوق السهم، مش سهم لتحت بعد الناتج."}],"explanation":"السهم اللي لتحت ↓ بعد الـ $\\ce{Cu(OH)2}$ معناه إنه precipitate: solid مش بيدوب وبيتكوّن في الـ solution. أما خروج gas فبيتكتب ↑، والحرارة بتتكتب $\\Delta$ فوق السهم."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":4,"is_basics":true,"lesson_no":4,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-chem.reaction-types","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Types of chemical reactions: from zero","duration_s":380.889,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.reaction-types","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Types of chemical reactions","duration_s":45.1,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":83,"page_to":83,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":56,"page_to":56,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-stoich.molar-mass","kind":"lesson","version":2,"catalog_version":3,"ord":351,"primary_concept_id":"stoich.molar-mass","concepts":[{"concept_id":"stoich.molar-mass","role":"primary"}],"title":"Molar mass","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"g":{"type":"Text","props":{"muted":true,"content":"A mole is a fixed count of particles (Avogadro's number, $6.02 \\times 10^{23}$)."},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"72 g","correct":false},{"id":"b","text":"160 g","correct":true},{"id":"c","text":"5 g","correct":false}],"question":"Predict: Fe = 56 and O = 16. What is the mass of one mole of $\\ce{Fe2O3}$?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"The book's ore table lists $\\ce{Fe2O3}$, $\\ce{Fe3O4}$ and $\\ce{FeCO3}$. To compare their iron, we need the mass of one mole of each."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","g","q"]}}},"title":"How heavy is one mole of ore?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Callout","props":{"variant":"tip"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Molar mass","definition":"The sum of atomic masses of the elements forming the molecule or formula unit, measured in grams (g/mol)."},"children":[]},"m":{"type":"DataTable","props":{"rows":[["Atomic mass",56,16,12,1]],"caption":"Rounded atomic masses used in exam problems","headers":["Element","Fe","O","C","H"]},"children":[]},"t":{"type":"Text","props":{"content":"Multiply each atomic mass by the number of its atoms. Then add."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","m","t","c"]}}},"title":"Molar mass"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"M(\\ce{Fe2O3}) = 2 \\times 56 + 3 \\times 16 = 112 + 48 = 160\\ \\text{g/mol}","caption":"Fe₂O₃: 2 Fe atoms, 3 O atoms"},"children":[]},"r":{"type":"Reveal","props":{"label":"Show limonite"},"children":["f2","t2"]},"t":{"type":"Text","props":{"content":"Limonite has water of crystallization. The dot means: add the water's mass too."},"children":[]},"f2":{"type":"Formula","props":{"latex":"M(\\ce{2Fe2O3*3H2O}) = 2 \\times 160 + 3 \\times 18 = 374\\ \\text{g/mol}"},"children":[]},"t2":{"type":"Text","props":{"size":"sm","content":"Each $\\ce{H2O}$ is 2 × 1 + 16 = 18. The numbers in front multiply the whole unit."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","r"]}}},"title":"Worked example: hematite"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"x":1,"y":1},"elements":{"t":{"type":"Text","props":{"content":"Set the number of Fe and O atoms. Try FeO, $\\ce{Fe3O4}$ and $\\ce{Fe2O3}$."},"children":[]},"x":{"type":"Slider","props":{"max":3,"min":1,"step":1,"label":"Fe atoms","value":{"$bindState":"/x"}},"children":[]},"y":{"type":"Slider","props":{"max":4,"min":1,"step":1,"label":"O atoms","value":{"$bindState":"/y"}},"children":[]},"sf":{"type":"Stat","props":{"tone":"neutral","unit":"g","label":"Mass of Fe","value":{"args":{"x":{"$state":"/x"},"expr":"56*x","digits":0},"$computed":"calc"}},"children":[]},"sm":{"type":"Stat","props":{"tone":"brand","unit":"g/mol","label":"Molar mass","value":{"args":{"x":{"$state":"/x"},"y":{"$state":"/y"},"expr":"56*x + 16*y","digits":0},"$computed":"calc"}},"children":[]},"row":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["sf","sm"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","x","y","row"]}}},"title":"Build an iron oxide"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"Siderite, $\\ce{FeCO3}$: molar mass = ___ g/mol (Fe = 56, C = 12, O = 16).","answers":[["116"]],"mistakes":[{"id":"m1","blank":0,"answer":"84"},{"id":"m2","blank":0,"answer":"72"},{"id":"m3","blank":0,"answer":"348"},{"id":"m4","blank":0,"answer":"5"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"28 g/mol","correct":false},{"id":"b","text":"30 g/mol","correct":false},{"id":"c","text":"44 g/mol","correct":true},{"id":"d","text":"88 g/mol","correct":false}],"question":"Coke burns to $\\ce{CO2}$ in the blast furnace. What is the molar mass of $\\ce{CO2}$?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","q"]}}},"title":"Your turn: siderite and CO₂"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Molar mass = sum of the atomic masses in the formula, in g/mol.","A subscript multiplies the atom, or the bracketed group, just before it.","In a hydrate, add the mass of the water of crystallization."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"n":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"ans":{"type":"Reveal","props":{},"children":["anst"]},"anst":{"type":"Text","props":{"content":"$\\ce{Fe2O3}$ has 2 Fe atoms and 3 O atoms: 2 × 56 + 3 × 16 = 112 + 48 = 160 g/mol, so one mole has a mass of 160 g."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","n","self","ans"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why one mole of $\\ce{Fe2O3}$ has a mass of 160 g?"},"children":[]}}},"title":"Summary"}],"title":"Molar mass","minutes":5,"book_ref":"Prerequisite (1st secondary); definition in Ch.2 'Feed Back' p.30; used with the iron ores table, Ch.1 p.16-17","subtitle":"Adding atomic masses, ready for iron ores","objectives":["Calculate the molar mass of a compound from its formula and atomic masses.","Use the subscripts and coefficients in a formula correctly, including a hydrated ore."],"concept_ids":["stoich.molar-mass"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"That is 56 + 16: one Fe and one O, but $\\ce{Fe2O3}$ holds 2 Fe and 3 O."},{"id":"b","feedback":"Good thinking. Each atom in the formula adds its own mass."},{"id":"c","feedback":"That counts atoms (2 + 3), not their masses: each atom adds its own mass (Fe = 56, O = 16)."}],"explanation":"One mole of $\\ce{Fe2O3}$ holds 2 Fe and 3 O: 2 × 56 + 3 × 16 = 112 + 48 = 160 g."}},"s2":{"c":{"body":"A subscript multiplies the atom, or the bracketed group, just before it. In $\\ce{CO3}$ the 3 counts O only; in $\\ce{Fe2(SO4)3}$ it counts the whole $\\ce{SO4}$ group."}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"You counted O once, but the subscript 3 belongs to O: there are three O atoms."},{"id":"m2","feedback":"You added Fe and one O, so the carbon and two of the O atoms are missing."},{"id":"m3","feedback":"The 3 multiplies O, not Fe and C as well."},{"id":"m4","feedback":"That counts atoms; the molar mass adds up each atom's mass."}],"explanation":"56 + 12 + 3 × 16 = 116 g/mol."},"q":{"options":[{"id":"a","feedback":"That is the mass of CO, but $\\ce{CO2}$ has two O atoms."},{"id":"b","feedback":"It looks like the 2 was added as a mass, but the subscript multiplies the number of O atoms."},{"id":"c","feedback":"Right: 12 + 2 × 16 = 44 g/mol."},{"id":"d","feedback":"The 2 belongs to O, so the carbon is not doubled."}],"explanation":"$\\ce{CO2}$ has one C and two O: 12 + 2 × 16 = 44 g/mol."}},"s6":{"e":{"body":"Show the working: number of atoms × atomic mass, then add. Write the unit g/mol."},"n":{"body":"You will use molar mass to find the percentage of iron in an ore."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"ده 56 + 16: يعني Fe واحد و O واحد، لكن الـ $\\ce{Fe2O3}$ فيه 2 ذرة Fe و3 ذرات O، وكل ذرة بتضيف كتلتها."},{"id":"b","feedback":"تفكير حلو. أي ذرة في الـ formula بتضيف الكتلة بتاعتها هي."},{"id":"c","feedback":"كده إنت عدّيت الذرات (2 + 3)، مش كتلتها. كتلة الـ mole بتيجي من جمع كتل الذرات (Fe = 56 و O = 16)، مش من عددها."}],"explanation":"الـ mole الواحد من الـ $\\ce{Fe2O3}$ فيه 2 Fe و 3 O: 2 × 56 + 3 × 16 = 112 + 48 = 160 g."}},"s2":{"c":{"body":"الـ subscript بيضرب في الذرة، أو المجموعة اللي بين قوسين، اللي قبله على طول. في الـ $\\ce{CO3}$ الـ 3 بتعدّ الـ O لوحده؛ وفي الـ $\\ce{Fe2(SO4)3}$ بتعدّ مجموعة الـ $\\ce{SO4}$ كلها."}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"إنت حسبت الـ O مرة واحدة، لكن الـ subscript 3 تبع الـ O، يعني فيه 3 ذرات O."},{"id":"m2","feedback":"إنت جمعت الـ Fe و O واحد بس، ونسيت الـ carbon، والـ O نفسه فيه 3 ذرات."},{"id":"m3","feedback":"الـ 3 بيضرب في الـ O لوحده، مش في الـ Fe والـ C كمان."},{"id":"m4","feedback":"كده إنت بتعدّ الذرات، والمطلوب كتلة الذرات نفسها مش عددها."}],"explanation":"الحساب: 56 + 12 + 3 × 16 = 116 g/mol."},"q":{"options":[{"id":"a","feedback":"دي كتلة الـ CO، لكن الـ $\\ce{CO2}$ فيه ذرتين O."},{"id":"b","feedback":"شكلك جمعت الـ 2 كأنه كتلة. الـ subscript بيضرب في كتلة الـ O، مش بيتجمع عليها."},{"id":"c","feedback":"صح: 12 + 2 × 16 = 44 g/mol."},{"id":"d","feedback":"الـ 2 تبع الـ O لوحده، فالـ carbon بيتحسب مرة واحدة بس، مش مرتين."}],"explanation":"الـ $\\ce{CO2}$ فيه C واحد و O اتنين: 12 + 2 × 16 = 44 g/mol."}},"s6":{"e":{"body":"اكتب خطوات الحل: عدد الذرات × الـ atomic mass، وبعدين اجمع. واكتب الوحدة g/mol."},"n":{"body":"هتستخدم الـ molar mass عشان تحسب نسبة الـ iron في الـ ore."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":5,"is_basics":true,"lesson_no":5,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-stoich.molar-mass","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Molar mass: from zero","duration_s":333.85,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-stoich.molar-mass","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Molar mass","duration_s":51.7,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-stoich.mass-percentage","kind":"lesson","version":2,"catalog_version":3,"ord":353,"primary_concept_id":"stoich.mass-percentage","concepts":[{"concept_id":"stoich.mass-percentage","role":"primary"}],"title":"Mass percentage of an element","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{Fe3O4}$","correct":true},{"id":"b","text":"$\\ce{Fe2O3}$","correct":false},{"id":"c","text":"Equal: both are just iron and oxygen","correct":false}],"question":"Predict: which has the higher percentage of iron by mass?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Magnetite ($\\ce{Fe3O4}$) and hematite ($\\ce{Fe2O3}$) are both iron oxides. Which pure oxide has the larger share of iron?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Which oxide is richer in iron?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\%\\,\\ce{Fe} = \\dfrac{\\text{mass of Fe in 1 mol}}{\\text{molar mass}} \\times 100"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Mass percentage of an element","definition":"Mass of the element in one mole of the compound × 100 / molar mass of the compound."},"children":[]},"t":{"type":"Text","props":{"content":"Mass of the element = number of its atoms × its atomic mass."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t"]}}},"title":"The formula"},{"id":"s3","kind":"example","spec":{"root":"root","state":{"x":3,"y":4},"elements":{"b":{"type":"BulletList","props":{"items":["Molar mass of $\\ce{Fe3O4}$ = 3 × 56 + 4 × 16 = 232 g/mol","Mass of Fe in 1 mol = 3 × 56 = 168 g","% Fe = 168 / 232 × 100 = 72.4%"],"ordered":true},"children":[]},"m":{"type":"DataTable","props":{"rows":[["Atomic mass",56,16,12,1]],"caption":"Rounded atomic masses used in exam problems","headers":["Element","Fe","O","C","H"]},"children":[]},"t":{"type":"Text","props":{"content":"Now try it live: change the atoms and watch the percentage."},"children":[]},"x":{"type":"Slider","props":{"max":3,"min":1,"step":1,"label":"Fe atoms","value":{"$bindState":"/x"}},"children":[]},"y":{"type":"Slider","props":{"max":4,"min":1,"step":1,"label":"O atoms","value":{"$bindState":"/y"}},"children":[]},"sf":{"type":"Stat","props":{"tone":"neutral","unit":"g","label":"Mass of Fe","value":{"args":{"x":{"$state":"/x"},"expr":"56*x","digits":0},"$computed":"calc"}},"children":[]},"sp":{"type":"Stat","props":{"tone":"brand","unit":"%","label":"% Fe","value":{"args":{"x":{"$state":"/x"},"y":{"$state":"/y"},"expr":"56*x/(56*x + 16*y)*100","digits":1},"$computed":"calc"}},"children":[]},"row":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["sf","sp"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["m","b","t","x","y","row"]}}},"title":"Worked example: magnetite"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"Siderite, $\\ce{FeCO3}$ (molar mass 116 g/mol): % Fe = ___ % (one decimal place).","answers":[["48.3","48.28","48.276","48.3%","48"]],"mistakes":[{"id":"m1","blank":0,"answer":"20"},{"id":"m2","blank":0,"answer":"56"},{"id":"m3","blank":0,"answer":"51.7"},{"id":"m4","blank":0,"answer":"0.48"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The ore holds impurities. They add mass but no iron.","correct":true},{"id":"b","text":"In the ground, the formula of $\\ce{Fe3O4}$ changes.","correct":false},{"id":"c","text":"Some iron atoms are lost when the ore is weighed.","correct":false},{"id":"d","text":"The percentage formula only works for pure metals.","correct":false}],"question":"Pure $\\ce{Fe3O4}$ is 72.4% iron. The book's table gives magnetite ore 45–70% iron. Why is the ore lower?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","q"]}}},"title":"Your turn: siderite"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["% element = mass of the element in 1 mol × 100 / molar mass.","Use masses, not the number of atoms.","An ore is lower in iron than its pure compound: impurities add mass."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"n":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"ans":{"type":"Reveal","props":{},"children":["anst"]},"anst":{"type":"Text","props":{"content":"$\\ce{Fe3O4}$ has 3 Fe for 4 O (0.75 per O); $\\ce{Fe2O3}$ has 2 Fe for 3 O (about 0.67 per O). More iron per oxygen gives the larger share: 72.4% against 70.0%."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","n","self","ans"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why $\\ce{Fe3O4}$ has a larger share of iron than $\\ce{Fe2O3}$?"},"children":[]}}},"title":"Summary"}],"title":"Mass percentage of an element","minutes":5,"book_ref":"Prerequisite (1st secondary); formula in Ch.2 'Feed Back' p.30; used with the iron ores table (Iron %), Ch.1 p.16","subtitle":"How much of an ore is iron?","objectives":["Calculate the mass percentage of iron in an iron compound.","Explain why an ore has a lower iron percentage than its pure compound."],"concept_ids":["stoich.mass-percentage"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. It has 3 Fe for 4 O; $\\ce{Fe2O3}$ has 2 Fe for 3 O. Let's check with numbers."},{"id":"b","feedback":"$\\ce{Fe2O3}$ has 2 Fe for 3 O, about 0.67 Fe per O: less iron per oxygen means a smaller iron share."},{"id":"c","feedback":"Same elements, but different ratios of atoms, and a different ratio gives a different iron share."}],"explanation":"$\\ce{Fe3O4}$ has 3 Fe to 4 O (0.75 per O); $\\ce{Fe2O3}$ has 2 Fe to 3 O (about 0.67 per O). More iron per oxygen gives $\\ce{Fe3O4}$ the higher iron percentage: 72.4% against 70.0%."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"That counts atoms (1 out of 5). The formula uses masses: iron's mass in one mole is 56 g."},{"id":"m2","feedback":"That is the mass of iron. It is divided by the molar mass, 116, before multiplying by 100."},{"id":"m3","feedback":"That is the share of everything except iron. The mass of iron goes on top of the fraction."},{"id":"m4","feedback":"You divided correctly. One step of the formula is still missing: multiplying by 100 turns the fraction into a percentage."}],"explanation":"56 / 116 × 100 = 48.3%."},"q":{"options":[{"id":"a","feedback":"Right. The same iron sits in a larger total mass, so the share is smaller."},{"id":"b","feedback":"A compound keeps its formula wherever it is found, so $\\ce{Fe3O4}$ in the ground is still $\\ce{Fe3O4}$."},{"id":"c","feedback":"Weighing does not remove atoms, so the iron in the sample stays the same."},{"id":"d","feedback":"The percentage formula works for any compound, not just for pure metals."}],"explanation":"Magnetite ore is $\\ce{Fe3O4}$ mixed with impurities. They add mass but no iron, so the same iron is a smaller share of the total: 45–70% instead of 72.4%."}},"s5":{"e":{"body":"Write the formula first, then substitute. Give the answer as a percentage."},"n":{"body":"Roasting siderite drives off $\\ce{CO2}$, so the ore's iron percentage rises overall."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. هنا فيه 3 Fe قصاد 4 O، والـ $\\ce{Fe2O3}$ فيه 2 Fe قصاد 3 O. يلا نتأكد بالأرقام."},{"id":"b","feedback":"الـ $\\ce{Fe2O3}$ فيه 2 Fe لكل 3 O، يعني حوالي 0.67 Fe لكل O: iron أقل لكل oxygen معناه نسبة iron أصغر."},{"id":"c","feedback":"نفس العناصر، لكن نسب الذرات مختلفة، والنسبة دي بتغيّر النصيب."}],"explanation":"الـ $\\ce{Fe3O4}$ فيه 3 Fe قصاد كل 4 O (يعني 0.75 لكل O)، والـ $\\ce{Fe2O3}$ فيه 2 Fe قصاد كل 3 O (حوالي 0.67 لكل O). الـ iron الأكتر بالنسبة للـ oxygen بيدّي الـ $\\ce{Fe3O4}$ نسبة iron أعلى: 72.4% قصاد 70.0%."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"كده إنت عدّيت الذرات (1 من 5)، والقانون بيستخدم الكتل، مش عدد الذرات."},{"id":"m2","feedback":"دي كتلة الـ iron لوحدها، ولسه لازم تتقسم على الـ molar mass قبل ما تضرب في 100."},{"id":"m3","feedback":"ده نصيب الباقي من غير الـ iron، وكتلة الـ iron هي اللي تتحط فوق في الكسر."},{"id":"m4","feedback":"القسمة مظبوطة، لكن الكسر لسه ما اتضربش في 100 عشان يبقى نسبة مئوية."}],"explanation":"الحساب: 56 / 116 × 100 = 48.3%."},"q":{"options":[{"id":"a","feedback":"صح. نفس الـ iron موجود في كتلة كلية أكبر، فالنصيب بيقل."},{"id":"b","feedback":"الـ compound بيفضل محافظ على الـ formula بتاعته في أي مكان يتلاقى فيه، فالـ $\\ce{Fe3O4}$ اللي في الأرض بيفضل $\\ce{Fe3O4}$."},{"id":"c","feedback":"الوزن مش بيشيل ذرات، فالـ iron مش بيضيع وإحنا بنوزن."},{"id":"d","feedback":"القانون بيشتغل مع أي compound، مش مع الـ pure metals لوحدها."}],"explanation":"الـ magnetite ore هو $\\ce{Fe3O4}$ متخلط بشوائب. الشوائب بتزوّد الكتلة من غير ما تزوّد iron، فنفس الـ iron نصيبه بيقل من الكتلة الكلية: 45–70% بدل 72.4%."}},"s5":{"e":{"body":"اكتب القانون الأول، وبعدين عوّض فيه. وطلّع الإجابة في الآخر كنسبة مئوية."},"n":{"body":"الـ roasting بتاع الـ siderite بيطرد الـ $\\ce{CO2}$، فنسبة الـ iron في الـ ore بتزيد في المجمل."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":6,"is_basics":true,"lesson_no":6,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-extraction","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron ores and extraction of iron","duration_s":734.029,"start_s":331.8,"end_s":358.5,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-stoich.mass-percentage","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Mass percentage of an element","duration_s":52.83,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.roasting","kind":"lesson","version":4,"catalog_version":3,"ord":355,"primary_concept_id":"fe.roasting","concepts":[{"concept_id":"fe.roasting","role":"primary"}],"title":"Roasting of iron ore","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Heating makes new iron atoms","correct":false},{"id":"b","text":"Heating reduces the ore to iron metal","correct":false},{"id":"c","text":"Gases leave the solid, and the iron stays","correct":true}],"question":"Predict: where does the higher percentage come from?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Pure $\\ce{FeCO3}$, the iron compound in siderite, is about 48% iron. After strong heating in air it ends up about 70% iron. Nobody added iron."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"More iron, with no iron added?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"FlowDiagram","props":{"edges":[{"to":"c","from":"p"}],"nodes":[{"id":"p","label":"Physical: crushing, sintering, concentrating"},{"id":"c","label":"Chemical: roasting"}],"caption":"Ore dressing: improving the physical, then the chemical properties of the ore"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Roasting","definition":"The ore is strongly heated in air."},"children":[]},"t":{"type":"Text","props":{"content":"Roasting improves the chemical properties of the ore. It is part of ore dressing, before reduction."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t"]}}},"title":"What roasting is"},{"id":"s3","kind":"explain","spec":{"root":"root","state":{"n":1},"elements":{"t":{"type":"Text","props":{"content":"Purpose (a): drying the ore and expelling humidity, to increase the percentage of iron in the ore."},"children":[]},"c1":{"type":"Text","props":{"size":"sm","content":"Thermal decomposition: $\\ce{CO2}$ gas leaves the solid."},"children":[]},"c2":{"type":"Text","props":{"size":"sm","content":"FeO gains oxygen from the air: oxidation. On its own, this step lowers % Fe (FeO about 78% → $\\ce{Fe2O3}$ about 70%). The rise is counted on siderite overall: $\\ce{FeCO3}$ (48% Fe) → $\\ce{Fe2O3}$ (about 70% Fe)."},"children":[]},"c3":{"type":"Text","props":{"size":"sm","content":"The water of crystallization leaves as vapour."},"children":[]},"e1":{"type":"Card","props":{"title":"Siderite decomposes"},"visible":{"eq":1,"$state":"/n"},"children":["f1","c1"]},"e2":{"type":"Card","props":{"title":"FeO is oxidized"},"visible":{"eq":2,"$state":"/n"},"children":["f2","c2"]},"e3":{"type":"Card","props":{"title":"Limonite loses its water"},"visible":{"eq":3,"$state":"/n"},"children":["f3","c3"]},"f1":{"type":"Formula","props":{"latex":"\\begin{aligned}&\\ce{FeCO3(s) ->[\\Delta]}\\\\&\\ce{FeO(s) + CO2(g)}\\end{aligned}"},"children":[]},"f2":{"type":"Formula","props":{"latex":"\\begin{aligned}&\\ce{2FeO(s) + 1/2O2(g) ->[\\Delta]}\\\\&\\ce{Fe2O3(s)}\\end{aligned}","caption":"Siderite overall: 48% Fe → about 70% Fe (the book prints 69.6%)"},"children":[]},"f3":{"type":"Formula","props":{"latex":"\\begin{aligned}&\\ce{2Fe2O3*3H2O(s) ->[\\Delta]}\\\\&\\ce{2Fe2O3(s) + 3H2O(v)}\\end{aligned}"},"children":[]},"sl":{"type":"Slider","props":{"max":3,"min":1,"step":1,"label":"Equation","value":{"$bindState":"/n"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","e1","e2","e3"]}}},"title":"Purpose 1: more iron in the ore"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Follow 2 mol of pure $\\ce{FeCO3}$ all the way to $\\ce{Fe2O3}$ (Fe = 56, C = 12, O = 16)."},"children":[]},"t2":{"type":"Text","props":{"content":"The iron mass does not change. The total mass falls, so iron's share rises."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Before: 2 FeCO₃","232 g","112 g","48.3%"],["After: Fe₂O₃","160 g","112 g","70.0%"]],"caption":"Rounded atomic masses. The book's labels: 48.5% (FeCO₃) and 69.6% (Fe₂O₃).","headers":["","Total mass","Mass of Fe","% Fe"],"highlight":[{"col":2,"row":0},{"col":2,"row":1}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","tb","t2"]}}},"title":"Why the iron percentage rises"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{S(s) + O2(g) ->[\\Delta] SO2(g)}"},"children":[]},"t":{"type":"Text","props":{"content":"Purpose (b): oxidation of some impurities such as sulphur and phosphorus."},"children":[]},"eb":{"type":"EquationBuilder","props":{"prompt":"Balance the phosphorus equation.","answers":[4,5,2],"template":"\\ce{{?}P(s) + {?}O2(g) -> {?}P2O5(s)}","conditions":"Δ"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Roasting melts sulphur and phosphorus out of the ore."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","f","tf","eb"]}}},"title":"Purpose 2: oxidizing impurities"},{"id":"s6","kind":"interact","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Sort each roasting reaction by what happens to it."},"children":[]},"cl":{"type":"Classify","props":{"items":[{"id":"i1","text":"$\\ce{FeCO3 -> FeO + CO2}$"},{"id":"i2","text":"$\\ce{2FeO + 1/2O2 -> Fe2O3}$"},{"id":"i3","text":"Limonite loses $\\ce{3H2O}$ on heating"},{"id":"i4","text":"$\\ce{S + O2 -> SO2}$"},{"id":"i5","text":"$\\ce{4P + 5O2 -> 2P2O5}$"}],"answer":{"ox":["i2","i4","i5"],"dec":["i1","i3"],"red":[]},"prompt":"Sort the reactions.","categories":[{"id":"dec","label":"Thermal decomposition"},{"id":"ox","label":"Oxidation (gains oxygen)"},{"id":"red","label":"Reduction (loses oxygen)"}]},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Roasting reduces the ore."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","cl","tf"]}}},"title":"Decomposition or oxidation?"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Water vapour leaves; the iron stays in less total mass.","correct":true},{"id":"b","text":"The heat reduces $\\ce{Fe2O3}$ to iron.","correct":false},{"id":"c","text":"Oxygen from the air turns into iron.","correct":false},{"id":"d","text":"Iron from the furnace walls joins the ore.","correct":false}],"question":"Limonite, $\\ce{2Fe2O3*3H2O}$, is roasted. Why does the iron percentage of the solid rise?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"In roasting, sulphur impurity is reduced to $\\ce{SO2}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Check yourself"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Roasting: the ore is strongly heated in air.","(a) Drying the ore and expelling humidity, to increase the percentage of iron.","(b) Oxidation of some impurities such as sulphur and phosphorus.","Iron stays; gases ($\\ce{CO2}$, water vapour) leave. The ore is not reduced here."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a","label":"$\\Delta$, $\\ce{CO2}$ leaves"},{"to":"c","from":"b","label":"$+\\ce{O2}$ of the air"}],"nodes":[{"id":"a","label":"$\\ce{FeCO3}$ (48% Fe)"},{"id":"b","label":"$\\ce{FeO}$"},{"id":"c","label":"$\\ce{Fe2O3}$ (about 70% Fe)"}],"layout":"horizontal","caption":"Siderite in roasting: gases leave, oxygen is added, iron stays"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fd","b","e","self"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain how siderite becomes richer in iron without any iron added?"},"children":[]}}},"title":"Summary"}],"title":"Roasting of iron ore","minutes":8,"book_ref":"Ch.1 'Extraction of Iron from its Ores', Firstly: Ore dressing, 2- Improving the chemical properties: Roasting, p.17","subtitle":"Heating in air: drier ore, more iron, fewer impurities","objectives":["State the meaning of roasting and its two purposes in the book's words.","Write the roasting equations of siderite, FeO, limonite, sulphur and phosphorus.","Explain why roasting raises the iron percentage of the ore.","Recognize that roasting oxidizes impurities and does not reduce the ore."],"concept_ids":["fe.roasting"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Heating cannot create atoms, so the iron mass stays the same; the rise comes from gases leaving the solid."},{"id":"b","feedback":"Reducing means removing oxygen, but this heating happens in air, which supplies oxygen: the ore is not reduced here."},{"id":"c","feedback":"Good thinking. Same iron in a smaller total mass gives a larger share."}],"explanation":"Heating in air cannot create iron atoms and does not reduce the ore. Gases ($\\ce{CO2}$, water vapour) leave the solid, so the same iron mass sits in a smaller total mass and its percentage rises."}},"s5":{"eb":{"explanation":"4 P and 10 O on each side."},"tf":{"explanation":"Sulphur and phosphorus are not melted out: they react with the oxygen of the air and are oxidized to $\\ce{SO2}$ and $\\ce{P2O5}$.","feedback_true":"Not melted out. Sulphur and phosphorus react with the oxygen of the air: they are oxidized, to $\\ce{SO2}$ and $\\ce{P2O5}$, as the equations show.","feedback_false":"Right. In roasting they are oxidized by the oxygen of the air, as the equations show."}},"s6":{"cl":{"items":[{"id":"i1","feedback":"Nothing is taken from the air here: one substance breaks into two on heating."},{"id":"i2","feedback":"The $\\ce{O2}$ on the left shows FeO taking oxygen from the air."},{"id":"i3","feedback":"Limonite does not react with the air here: one substance breaks up on heating, giving off water."},{"id":"i4","feedback":"Sulphur combines with oxygen from the air here."},{"id":"i5","feedback":"Phosphorus combines with oxygen from the air here."}],"explanation":"On heating, $\\ce{FeCO3}$ and limonite break up (thermal decomposition), while FeO, sulphur and phosphorus gain oxygen from the air (oxidation). Removing oxygen from iron oxides (reduction) comes in the next stage, after roasting."},"tf":{"explanation":"Roasting is heating in air: substances break up or gain oxygen. Removing oxygen from the iron oxides (reduction) comes in the next stage.","feedback_true":"Not in roasting. It is heating in air: substances break up or gain oxygen. Removing oxygen from iron oxides (reduction) comes in the next stage.","feedback_false":"Right. In roasting, substances break up or gain oxygen. Reduction of the iron oxides comes in the next stage."}},"s7":{"q":{"options":[{"id":"a","feedback":"Right. Same iron mass, smaller total mass, larger share."},{"id":"b","feedback":"Roasting happens in air and the product is still $\\ce{Fe2O3}$: no oxygen is removed from the iron."},{"id":"c","feedback":"One element cannot turn into another in a reaction; water vapour leaves the solid instead."},{"id":"d","feedback":"The furnace does not add iron; the solid loses its water of crystallization."}],"explanation":"On roasting, limonite loses its water of crystallization as vapour: $\\ce{2Fe2O3*3H2O -> 2Fe2O3 + 3H2O}$. The iron mass stays the same in a smaller total mass, so the iron percentage of the solid rises."},"tf":{"explanation":"In $\\ce{S + O2 -> SO2}$ sulphur gains oxygen from the air, so it is oxidized, not reduced.","feedback_true":"Sulphur gains oxygen in $\\ce{S -> SO2}$: it is oxidized, not reduced.","feedback_false":"Right. Sulphur gains oxygen: it is oxidized."}},"s8":{"e":{"body":"Give reasons: the iron percentage rises on roasting. Key words: moisture and gases expelled; iron mass stays; total mass decreases."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"التسخين مايقدرش يخلق ذرات، يعني كتلة الـ iron بتفضل زي ما هي؛ والزيادة جاية من الغازات اللي بتخرج من المادة الصلبة."},{"id":"b","feedback":"الـ reduction يعني إنك تشيل oxygen، لكن التسخين ده بيحصل في الهوا، والهوا بيدّي oxygen: الـ ore مش بيحصله reduction هنا."},{"id":"c","feedback":"تفكير حلو. نفس الـ iron في كتلة كلية أصغر، يبقى نصيبه أكبر."}],"explanation":"التسخين في الهوا مايقدرش يخلق ذرات iron ومش بيعمل reduction للـ ore. الغازات ($\\ce{CO2}$ وبخار الميّة) بتخرج من المادة الصلبة، فنفس كتلة الـ iron بتبقى في كتلة كلية أصغر ونسبته بتزيد."}},"s5":{"eb":{"explanation":"4 P و10 O على الناحيتين."},"tf":{"explanation":"الـ sulphur والـ phosphorus مش بيسيحوا ويخرجوا: بيتفاعلوا مع الـ oxygen اللي في الهوا وبيحصلهم oxidation لـ $\\ce{SO2}$ و $\\ce{P2O5}$.","feedback_true":"لأ، مش بيسيحوا ويخرجوا. الـ sulphur والـ phosphorus بيتفاعلوا مع الـ oxygen اللي في الهوا: بيحصلهم oxidation لـ $\\ce{SO2}$ و $\\ce{P2O5}$، زي ما المعادلات بتقول.","feedback_false":"صح. في الـ roasting بيحصلهم oxidation بالـ oxygen اللي في الهوا، زي ما المعادلات بتقول."}},"s6":{"cl":{"items":[{"id":"i1","feedback":"مفيش حاجة بتتاخد من الهوا هنا: مادة واحدة بتتكسر لاتنين."},{"id":"i2","feedback":"بص على الـ $\\ce{O2}$ اللي على الشمال: الـ FeO بيكسب الـ oxygen ده."},{"id":"i3","feedback":"هنا مفيش تفاعل مع الهوا: مادة واحدة بتتكسر لما نسخّنها."},{"id":"i4","feedback":"الـ sulphur هنا بيكسب oxygen من الهوا."},{"id":"i5","feedback":"الـ phosphorus هنا بيكسب oxygen من الهوا."}],"explanation":"لما بنسخّن، الـ $\\ce{FeCO3}$ والـ limonite بيتكسروا (thermal decomposition)، في حين إن الـ FeO والـ sulphur والـ phosphorus بيكسبوا oxygen من الهوا (oxidation). شيل الـ oxygen من الـ iron oxides (الـ reduction) بييجي في المرحلة اللي بعد الـ roasting."},"tf":{"explanation":"الـ roasting تسخين في الهوا: المواد بتتكسر أو بتكسب oxygen. شيل الـ oxygen من الـ iron oxides (الـ reduction) بييجي في المرحلة اللي بعدها.","feedback_true":"مش في الـ roasting. ده تسخين في الهوا: المواد بتتكسر أو بتكسب oxygen. شيل الـ oxygen من الـ iron oxides (الـ reduction) بييجي في المرحلة اللي بعدها.","feedback_false":"صح. في الـ roasting المواد بتتكسر أو بتكسب oxygen. الـ reduction بتاع الـ iron oxides بييجي في المرحلة اللي بعدها."}},"s7":{"q":{"options":[{"id":"a","feedback":"صح. نفس كتلة الـ iron، في كتلة كلية أصغر، يبقى النسبة أكبر."},{"id":"b","feedback":"الـ roasting بيحصل في الهوا والناتج لسه $\\ce{Fe2O3}$: مفيش oxygen بيتشال من الـ iron."},{"id":"c","feedback":"مفيش عنصر بيتحول لعنصر تاني في التفاعل؛ اللي بيخرج من المادة الصلبة هو بخار الميّة."},{"id":"d","feedback":"الفرن مش بيضيف iron؛ المادة الصلبة بتخسر الـ water of crystallization بتاعها."}],"explanation":"في الـ roasting الـ limonite بيخسر الـ water of crystallization بتاعه على شكل بخار: $\\ce{2Fe2O3*3H2O -> 2Fe2O3 + 3H2O}$. كتلة الـ iron بتفضل زي ما هي في كتلة كلية أصغر، فنسبة الـ iron في المادة الصلبة بتزيد."},"tf":{"explanation":"في $\\ce{S + O2 -> SO2}$ الـ sulphur بيكسب oxygen من الهوا، يعني بيحصله oxidation، مش reduction.","feedback_true":"الـ sulphur بيكسب oxygen في $\\ce{S -> SO2}$: يعني بيحصله oxidation، مش reduction.","feedback_false":"صح. الـ sulphur بيكسب oxygen، يعني بيحصله oxidation."}},"s8":{"e":{"body":"في سؤال Give reasons على إن نسبة الـ iron بتزيد بالـ roasting، دي الـ key words: moisture and gases expelled؛ iron mass stays؛ total mass decreases."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":4,"lesson_no":11,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-extraction","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron ores and extraction of iron","duration_s":734.029,"start_s":262.8,"end_s":397.3,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.roasting","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Roasting of iron ore","duration_s":49.07,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.blast-furnace-reduction","kind":"lesson","version":2,"catalog_version":3,"ord":357,"primary_concept_id":"fe.blast-furnace-reduction","concepts":[{"concept_id":"fe.blast-furnace-reduction","role":"primary"}],"title":"Reduction in the blast furnace","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Solid coke, directly","correct":false},{"id":"b","text":"Carbon dioxide, $\\ce{CO2}$","correct":false},{"id":"c","text":"Carbon monoxide, CO, made from the coke","correct":true},{"id":"d","text":"Oxygen from the air","correct":false}],"question":"Predict: in the book's equations, what takes the oxygen from $\\ce{Fe2O3}$?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Roasted iron ore is iron oxide. To get iron, the oxygen must be removed. The blast furnace is fed with coke, a form of carbon."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Who takes the oxygen?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"FlowDiagram","props":{"edges":[{"to":"r","from":"d"},{"to":"p","from":"r"}],"nodes":[{"id":"d","label":"Ore dressing"},{"id":"r","label":"Reduction of iron ores"},{"id":"p","label":"Iron production"}],"caption":"Extraction of iron from its ores: three stages (book p.17-18)"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Reduction of iron ores","definition":"The reduction of iron oxides to iron, by one of two methods depending on the reducing agent."},"children":[]},"t":{"type":"Text","props":{"content":"Method (a): carbon monoxide from coke, in the blast furnace. Method (b), the Midrex furnace, comes next."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","k","t"]}}},"title":"Reduction of iron ores"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Coke","definition":"A solid fuel made from coal. It is mostly carbon."},"children":[]},"t":{"type":"Text","props":{"content":"Coke burns to $\\ce{CO2}$. The $\\ce{CO2}$ meets more hot coke and becomes CO."},"children":[]},"f1":{"type":"Formula","props":{"latex":"\\ce{C(s) + O2(g) ->[\\Delta] CO2(g)}"},"children":[]},"f2":{"type":"Formula","props":{"latex":"\\ce{CO2(g) + C(s) ->[\\Delta] 2CO(g)}"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f1","f2","t"]}}},"title":"Coke makes carbon monoxide"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{3CO(g) + Fe2O3(s) ->[\\text{higher than } 700\\,^{\\circ}\\text{C}] 2Fe(s) + 3CO2(g)}"},"children":[]},"t":{"type":"Text","props":{"content":"The book's condition: higher than 700 °C."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["CO","gains O → CO₂","oxidized: the reducing agent"],["Fe₂O₃","loses O → Fe","reduced"]],"headers":["Substance","Oxygen","So it is"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","tb","t"]}}},"title":"CO reduces the ore"},{"id":"s5","kind":"interact","spec":{"root":"root","state":{"n":0},"elements":{"a":{"type":"Stat","props":{"tone":"brand","label":"O removed","value":{"args":{"n":{"$state":"/n"},"expr":"min(n, 3)","digits":0},"$computed":"calc"}},"children":[]},"b":{"type":"Stat","props":{"tone":"warning","label":"O still on the iron","value":{"args":{"n":{"$state":"/n"},"expr":"3 - min(n, 3)","digits":0},"$computed":"calc"}},"children":[]},"t":{"type":"Text","props":{"content":"Each CO takes one oxygen atom. Add CO molecules to one $\\ce{Fe2O3}$."},"children":[]},"c1":{"type":"Callout","props":{"variant":"tip"},"visible":{"eq":3,"$state":"/n"},"children":[]},"c2":{"type":"Callout","props":{"variant":"info"},"visible":{"eq":4,"$state":"/n"},"children":[]},"eb":{"type":"EquationBuilder","props":{"prompt":"Now balance it yourself.","answers":[3,1,2,3],"template":"\\ce{{?}CO(g) + {?}Fe2O3(s) -> {?}Fe(s) + {?}CO2(g)}","conditions":"higher than 700 °C"},"children":[]},"sl":{"type":"Slider","props":{"max":4,"min":0,"step":1,"label":"CO molecules","value":{"$bindState":"/n"}},"children":[]},"row":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["a","b"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","row","c1","c2","eb"]}}},"title":"Why 3 CO?"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"Callout","props":{"variant":"info"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Contrast: $\\ce{CO2}$ is not a reducing agent here. Its carbon has already gained all the oxygen it takes in these reactions."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"c2","from":"c","label":"burns in O₂"},{"to":"co","from":"c2","label":"+ more hot coke"},{"to":"fe","from":"co","label":"takes the O"}],"nodes":[{"id":"c","label":"Coke, C"},{"id":"c2","label":"CO₂"},{"id":"co","label":"CO"},{"id":"fe","label":"Fe₂O₃ → 2Fe"}],"layout":"horizontal","caption":"Coke is the source; CO takes the oxygen"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["m","fd","t","k"]}}},"title":"Coke or CO?"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"New case: $\\ce{CuO + CO ->[\\Delta] Cu + CO2}$. The reducing agent is ___ and the substance reduced is ___.","answers":[["co","carbon monoxide"],["cuo","copper oxide","copper(ii) oxide","copper ii oxide"]],"mistakes":[{"id":"m1","blank":0,"answer":"co2"},{"id":"m2","blank":0,"answer":"cuo"},{"id":"m3","blank":1,"answer":"cu"},{"id":"m4","blank":1,"answer":"co"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It reduces $\\ce{Fe2O3}$ directly to iron.","correct":false},{"id":"b","text":"It burns to $\\ce{CO2}$, which reduces the ore.","correct":false},{"id":"c","text":"It burns to $\\ce{CO2}$; with more coke this gives CO, which reduces the ore.","correct":true},{"id":"d","text":"It removes sulphur and phosphorus from the ore.","correct":false}],"question":"Exam question: \"Explain the role of coke in the blast furnace.\" Which answer gets full marks?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","f"]}}},"title":"Check yourself"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["$\\ce{C + O2 -> CO2}$, then $\\ce{CO2 + C -> 2CO}$.","$\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$, higher than 700 °C.","CO is the reducing agent; coke is its source."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"In $\\ce{CO2}$, carbon already holds two oxygen atoms, so it cannot take one more. CO can still gain an oxygen atom: $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why CO, not $\\ce{CO2}$, reduces the ore?"},"children":[]}}},"title":"Summary"}],"title":"Reduction in the blast furnace","minutes":8,"book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (a), p.18; Evaluation Q5.1, p.26","subtitle":"Coke makes the gas that takes the oxygen","objectives":["Write the three blast furnace equations with their conditions.","Identify carbon monoxide as the reducing agent of the ore.","Explain the role of coke in the blast furnace."],"concept_ids":["fe.blast-furnace-reduction"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"A natural guess, but in the book's equations solid coke never reacts with the ore: carbon first forms a gas."},{"id":"b","feedback":"In $\\ce{CO2}$, carbon already holds two oxygen atoms, so it cannot take one more."},{"id":"c","feedback":"Good thinking. CO can still gain an oxygen atom."},{"id":"d","feedback":"Oxygen adds oxygen, but the ore needs to lose oxygen, not gain it."}],"explanation":"Carbon monoxide, CO, made from the coke, takes the oxygen: $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$ above 700 °C. In $\\ce{CO2}$ carbon already holds two oxygen atoms, and oxygen from the air would add oxygen instead of removing it."}},"s5":{"c1":{"body":"Exactly enough: all 3 O atoms removed. You get 2Fe + 3CO₂."},"c2":{"body":"One CO is left over: $\\ce{Fe2O3}$ has only 3 O atoms."},"eb":{"explanation":"3 C, 2 Fe and 6 O on each side."}},"s6":{"k":{"body":"Role of coke: a fuel, and the source of carbon monoxide, the reducing agent."},"m":{"statement":"Coke itself reduces the ore.","correction":"In the book's equations, solid carbon never reacts with $\\ce{Fe2O3}$. Coke first makes CO, and CO reduces the ore."}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"That is a product; the reducing agent is the reactant that gains oxygen."},{"id":"m2","feedback":"This reactant loses oxygen, so it is the substance reduced, not the reducing agent."},{"id":"m3","feedback":"That is a product; the substance reduced is the reactant that loses its oxygen."},{"id":"m4","feedback":"This reactant gains oxygen, so it is the reducing agent, not the substance reduced."}],"explanation":"CO gains oxygen (reducing agent); CuO loses oxygen (reduced)."},"q":{"options":[{"id":"a","feedback":"Solid coke is not a reactant in the equation that makes Fe: the ore is reduced by CO, $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$."},{"id":"b","feedback":"Coke does burn to $\\ce{CO2}$, but in $\\ce{CO2}$ carbon already holds two oxygen atoms, so it cannot take oxygen from the ore."},{"id":"c","feedback":"Right. Coke is the source of CO, the reducing agent."},{"id":"d","feedback":"That belongs to an earlier stage, done by heating in air, not to the blast furnace."}],"explanation":"Coke burns to $\\ce{CO2}$, and $\\ce{CO2}$ reacts with more coke to give CO, which reduces the ore: $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$. So coke is the source of CO, the reducing agent."}},"s8":{"e":{"body":"Role of coke: \"a source of carbon monoxide, the reducing agent\". Write the three equations."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تخمين منطقي، لكن في معادلات الكتاب الـ coke الصلب عمره ما بيتفاعل مع الـ ore مباشرة."},{"id":"b","feedback":"في الـ $\\ce{CO2}$ الـ carbon شايل خلاص ذرتين oxygen، فمش هيقدر ياخد oxygen من الـ ore."},{"id":"c","feedback":"تفكير حلو. الـ CO لسه يقدر ياخد ذرة oxygen."},{"id":"d","feedback":"الـ oxygen بيزوّد oxygen، والـ ore محتاج يخسر oxygen مش يكسب."}],"explanation":"الـ carbon monoxide، يعني CO، اللي بيتكوّن من الـ coke، هو اللي بياخد الـ oxygen: $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$ عند أعلى من 700 °C. في الـ $\\ce{CO2}$ الـ carbon شايل خلاص ذرتين oxygen، والـ oxygen اللي في الهوا هيزوّد oxygen بدل ما يشيله."}},"s5":{"c1":{"body":"بالظبط كفاية: الـ 3 ذرات O اتشالوا كلهم. هيطلعلك 2Fe + 3CO₂."},"c2":{"body":"فيه CO واحد زيادة: الـ $\\ce{Fe2O3}$ مفيهوش غير 3 ذرات O."},"eb":{"explanation":"3 C و2 Fe و6 O في كل ناحية."}},"s6":{"k":{"body":"دور الـ coke: وقود (fuel)، وكمان مصدر الـ carbon monoxide، اللي هو الـ reducing agent."},"m":{"statement":"الـ coke نفسه هو اللي بيعمل reduction للـ ore.","correction":"في معادلات الكتاب الـ solid carbon عمره ما بيتفاعل مع الـ $\\ce{Fe2O3}$. الـ coke الأول بيكوّن CO، والـ CO هو اللي بيعمل reduction للـ ore."}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"ده product، والـ reducing agent بيبقى reactant بياخد oxygen."},{"id":"m2","feedback":"الـ reactant ده بيخسر oxygen، فهو المادة اللي حصلها reduction، مش الـ reducing agent."},{"id":"m3","feedback":"ده product، والمادة اللي حصلها reduction بتبقى reactant بيخسر الـ oxygen بتاعه."},{"id":"m4","feedback":"الـ reactant ده بياخد oxygen، فهو الـ reducing agent، مش المادة اللي حصلها reduction."}],"explanation":"الـ CO بياخد oxygen (الـ reducing agent)؛ والـ CuO بيخسر oxygen (reduced)."},"q":{"options":[{"id":"a","feedback":"الـ coke الصلب مش reactant في المعادلة اللي بتطلّع الـ Fe: الـ ore بيحصله reduction بالـ CO، $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$."},{"id":"b","feedback":"الـ coke فعلًا بيتحرق ويبقى $\\ce{CO2}$، لكن في الـ $\\ce{CO2}$ الـ carbon شايل خلاص ذرتين oxygen، فمش هيقدر ياخد oxygen من الـ ore."},{"id":"c","feedback":"صح. الـ coke هو مصدر الـ CO، اللي هو الـ reducing agent."},{"id":"d","feedback":"ده بتاع مرحلة قبل كده بتتعمل بالتسخين في الهوا، مش دور الـ coke في الـ blast furnace."}],"explanation":"الـ coke بيتحرق ويدي $\\ce{CO2}$، والـ $\\ce{CO2}$ بيتفاعل مع coke زيادة ويدي CO، والـ CO ده هو اللي بيعمل reduction للـ ore: $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$. يعني الـ coke هو مصدر الـ CO، اللي هو الـ reducing agent."}},"s8":{"e":{"body":"دور الـ coke في الامتحان: \"a source of carbon monoxide, the reducing agent\". واكتب المعادلات التلاتة."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":5,"lesson_no":12,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-extraction","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron ores and extraction of iron","duration_s":734.029,"start_s":405,"end_s":477.1,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.blast-furnace-reduction","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Reduction in the blast furnace","duration_s":48.27,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q5","section_title":"Explain the role","section_path":["Transition Elements","Evaluation","Explain the role"],"exercise":"Question 5","question":"1","relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.natural-gas-methane","kind":"lesson","version":2,"catalog_version":3,"ord":359,"primary_concept_id":"chem.natural-gas-methane","concepts":[{"concept_id":"chem.natural-gas-methane","role":"primary"}],"title":"Natural gas (methane)","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Hydrogen, $\\ce{H2}$","correct":false},{"id":"b","text":"Methane, $\\ce{CH4}$","correct":true},{"id":"c","text":"Oxygen, $\\ce{O2}$","correct":false},{"id":"d","text":"Carbon dioxide, $\\ce{CO2}$","correct":false}],"question":"Predict: what is natural gas mostly made of?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Many kitchen stoves in Egypt burn natural gas. The iron industry uses the same gas."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"The blue flame"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Chart","props":{"kind":"bar","unit":"%","series":[{"name":"Natural gas","points":[{"x":"Methane","y":93},{"x":"Other gases","y":7}]}],"caption":"The book's figure: natural gas is 93% methane.","x_label":"Part","y_label":"Percentage"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Natural gas","definition":"A gas fuel found underground. Its main part is methane, $\\ce{CH4}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","c"]}}},"title":"Natural gas"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 0 260 220\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><line x1=\"130\" y1=\"110\" x2=\"130\" y2=\"38\" stroke=\"#94a3b8\" stroke-width=\"4\"/><line x1=\"130\" y1=\"110\" x2=\"130\" y2=\"182\" stroke=\"#94a3b8\" stroke-width=\"4\"/><line x1=\"130\" y1=\"110\" x2=\"50\" y2=\"110\" stroke=\"#94a3b8\" stroke-width=\"4\"/><line x1=\"130\" y1=\"110\" x2=\"210\" y2=\"110\" stroke=\"#94a3b8\" stroke-width=\"4\"/><circle cx=\"130\" cy=\"38\" r=\"20\" fill=\"#60a5fa\" fill-opacity=\"0.3\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><text x=\"130\" y=\"45\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">H</text><circle cx=\"130\" cy=\"182\" r=\"20\" fill=\"#60a5fa\" fill-opacity=\"0.3\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><text x=\"130\" y=\"189\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">H</text><circle cx=\"50\" cy=\"110\" r=\"20\" fill=\"#60a5fa\" fill-opacity=\"0.3\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><text x=\"50\" y=\"117\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">H</text><circle cx=\"210\" cy=\"110\" r=\"20\" fill=\"#60a5fa\" fill-opacity=\"0.3\" stroke=\"#60a5fa\" stroke-width=\"2.5\"/><text x=\"210\" y=\"117\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#e2e8f0\">H</text><circle cx=\"130\" cy=\"110\" r=\"30\" fill=\"#fbbf24\" fill-opacity=\"0.3\" stroke=\"#fbbf24\" stroke-width=\"3\"/><text x=\"130\" y=\"119\" text-anchor=\"middle\" font-size=\"26\" font-weight=\"700\" fill=\"#e2e8f0\">C</text></svg>","caption":"Methane, CH₄: one carbon atom bonded to four hydrogen atoms","max_width":260},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Hydrocarbon","definition":"A compound made of carbon and hydrogen only."},"children":[]},"t":{"type":"Text","props":{"content":"Methane has one C atom, so it is the simplest hydrocarbon."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","k","t"]}}},"title":"Methane: the simplest hydrocarbon"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"The Midrex furnace uses $\\ce{2CH4}$. That is ___ carbon atoms and ___ hydrogen atoms.","answers":[["2","two"],["8","eight"]],"mistakes":[{"id":"m1","blank":0,"answer":"1"},{"id":"m2","blank":1,"answer":"4"},{"id":"m3","blank":1,"answer":"6"}]},"children":[]},"cl":{"type":"Classify","props":{"items":[{"id":"i1","text":"$\\ce{C3H8}$"},{"id":"i2","text":"$\\ce{CO2}$"},{"id":"i3","text":"$\\ce{H2O}$"},{"id":"i4","text":"$\\ce{C2H6}$"},{"id":"i5","text":"$\\ce{CO}$"}],"answer":{"hc":["i1","i4"],"no":["i2","i3","i5"]},"prompt":"Sort each substance.","categories":[{"id":"hc","label":"Hydrocarbon"},{"id":"no","label":"Not a hydrocarbon"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["cl","f"]}}},"title":"Your turn"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Natural gas is a fuel found underground; it is mostly methane (93% in the book).","Methane, $\\ce{CH4}$, is the simplest hydrocarbon: carbon and hydrogen only.","A number in front of a formula multiplies every atom in it."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"n":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"ans":{"type":"Reveal","props":{},"children":["ans_f","ans_t"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","n","self","ans"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why methane is called a hydrocarbon?"},"children":[]},"ans_f":{"type":"Formula","props":{"latex":"\\ce{CH4}"},"children":[]},"ans_t":{"type":"Text","props":{"content":"Methane, $\\ce{CH4}$, has one C atom and four H atoms: it is made of carbon and hydrogen only, so it is a hydrocarbon."},"children":[]}}},"title":"Summary"}],"title":"Natural gas (methane)","minutes":4,"book_ref":"Prerequisite (preparatory science); used in Ch.1 'Secondly: Reduction of Iron Ores' (b): natural gas (93% methane), p.18","subtitle":"The gas behind the Midrex furnace","objectives":["State that natural gas is mostly methane, $\\ce{CH4}$ (93% in the book).","Describe methane as the simplest hydrocarbon and count its atoms in an equation."],"concept_ids":["chem.natural-gas-methane"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Hydrogen atoms are in it, but bonded to another element, so natural gas is not mostly $\\ce{H2}$."},{"id":"b","feedback":"Good thinking. Methane is the main part of natural gas."},{"id":"c","feedback":"Oxygen helps a fuel burn, but it is not a fuel itself."},{"id":"d","feedback":"$\\ce{CO2}$ is what burning makes, so it cannot be the fuel."}],"explanation":"Natural gas is mostly methane, $\\ce{CH4}$, a compound of carbon and hydrogen that burns as a fuel. Oxygen helps the burning, and $\\ce{CO2}$ is a product of it."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"One molecule has one C, but the number in front counts more than one molecule."},{"id":"m2","feedback":"That is one molecule. The 2 in front multiplies the whole $\\ce{CH4}$."},{"id":"m3","feedback":"It looks like 2 and 4 were added, but the 2 in front multiplies; it does not add."}],"explanation":"2 × 1 = 2 C atoms and 2 × 4 = 8 H atoms."},"cl":{"items":[{"id":"i1","feedback":"$\\ce{C3H8}$ has no element besides C and H."},{"id":"i2","feedback":"$\\ce{CO2}$ contains O as well as C."},{"id":"i3","feedback":"$\\ce{H2O}$ contains O, and it has no C."},{"id":"i4","feedback":"$\\ce{C2H6}$ has no element besides C and H."},{"id":"i5","feedback":"$\\ce{CO}$ contains O as well as C."}],"explanation":"Hydrocarbons contain C and H only. O makes the others non-hydrocarbons."}},"s5":{"e":{"body":"Book wording: \"natural gas (93% methane)\"."},"n":{"body":"In the Midrex furnace, natural gas is turned into the gases that reduce iron ore."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"ذرات الـ hydrogen موجودة فيه فعلًا، لكنها مرتبطة بعنصر تاني، فالـ natural gas مش معظمه $\\ce{H2}$."},{"id":"b","feedback":"تفكير حلو. الـ methane هو المكوّن الأساسي للـ natural gas."},{"id":"c","feedback":"الـ oxygen بيساعد الوقود يتحرق، لكنه مش وقود في حد ذاته."},{"id":"d","feedback":"الـ $\\ce{CO2}$ ده اللي بيطلع من الاحتراق، فمينفعش يكون هو الوقود."}],"explanation":"الـ natural gas معظمه methane، يعني $\\ce{CH4}$، وده compound من الـ carbon والـ hydrogen بيتحرق كوقود. أما الـ oxygen فبيساعد على الاحتراق، والـ $\\ce{CO2}$ ناتج منه."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"الـ molecule الواحد فيه C واحد، لكن الرقم اللي قدام الصيغة بيعدّ أكتر من molecule."},{"id":"m2","feedback":"ده molecule واحد. الـ 2 اللي قدام بيضرب في الـ $\\ce{CH4}$ كله."},{"id":"m3","feedback":"شكلك جمعت الـ 2 والـ 4، لكن الـ 2 اللي قدام بيضرب، مش بيجمع."}],"explanation":"الحساب: 2 × 1 = 2 ذرات C، و 2 × 4 = 8 ذرات H."},"cl":{"items":[{"id":"i1","feedback":"الـ $\\ce{C3H8}$ مفيهوش أي عنصر غير الـ C والـ H."},{"id":"i2","feedback":"الـ $\\ce{CO2}$ فيه O جنب الـ C."},{"id":"i3","feedback":"الـ $\\ce{H2O}$ فيه O، ومفيهوش C أصلًا."},{"id":"i4","feedback":"الـ $\\ce{C2H6}$ مفيهوش أي عنصر غير الـ C والـ H."},{"id":"i5","feedback":"الـ $\\ce{CO}$ فيه O جنب الـ C."}],"explanation":"الـ Hydrocarbons مفيهاش غير C و H. وجود الـ O هو اللي بيخلّي الباقيين non-hydrocarbons."}},"s5":{"e":{"body":"صياغة الكتاب: \"natural gas (93% methane)\"."},"n":{"body":"في الـ Midrex furnace، الـ natural gas بيتحوّل للغازات اللي بتختزل الـ iron ore."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":7,"is_basics":true,"lesson_no":7,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-chem.natural-gas-methane","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Natural gas (methane): from zero","duration_s":307.49,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.natural-gas-methane","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Natural gas (methane)","duration_s":51.61,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.lesson-fe.midrex-reduction","kind":"lesson","version":2,"catalog_version":3,"ord":361,"primary_concept_id":"fe.midrex-reduction","concepts":[{"concept_id":"fe.midrex-reduction","role":"primary"}],"title":"Reduction in the Midrex furnace","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Methane, $\\ce{CH4}$, directly","correct":false},{"id":"b","text":"Coke, as in the blast furnace","correct":false},{"id":"c","text":"A mixture of CO and $\\ce{H2}$ made from natural gas","correct":true},{"id":"d","text":"Oxygen gas","correct":false}],"question":"Predict: in the Midrex furnace, what reduces the iron oxide?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Egypt produces natural gas. Can a furnace reduce iron ore with natural gas and no coke at all?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Iron without coke?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{2CH4(g) + CO2(g) + H2O(v) ->[\\Delta] 3CO(g) + 5H2(g)}"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Water gas","definition":"A mixture of carbon monoxide and hydrogen."},"children":[]},"t":{"type":"Text","props":{"content":"Natural gas (93% methane) is changed into water gas: $\\ce{3CO + 5H2}$."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["C",3,3],["H",10,10],["O",3,3]],"caption":"Atoms are conserved","headers":["Atoms","Left","Right"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t","tb"]}}},"title":"Natural gas becomes water gas"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{2Fe2O3(s) + 3CO(g) + 3H2(g) ->[\\Delta] 4Fe(s) + 3CO2(g) + 3H2O(v)}"},"children":[]},"t":{"type":"Text","props":{"content":"Both CO and $\\ce{H2}$ take oxygen from the ore. So both are reducing agents."},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"co2","from":"co","label":"gains O"},{"to":"w","from":"h","label":"gains O"}],"nodes":[{"id":"co","label":"CO"},{"id":"co2","label":"CO₂"},{"id":"h","label":"H₂"},{"id":"w","label":"H₂O"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","fl","t"]}}},"title":"Two reducing agents"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"c":0,"h":0},"elements":{"a":{"type":"Slider","props":{"max":6,"min":0,"step":1,"label":"CO molecules","value":{"$bindState":"/c"}},"children":[]},"b":{"type":"Slider","props":{"max":6,"min":0,"step":1,"label":"H₂ molecules","value":{"$bindState":"/h"}},"children":[]},"t":{"type":"Text","props":{"content":"Two $\\ce{Fe2O3}$ hold 6 O atoms. Each CO or $\\ce{H2}$ takes one. Set the mix."},"children":[]},"ok":{"type":"Callout","props":{"variant":"tip"},"visible":[{"eq":3,"$state":"/c"},{"eq":3,"$state":"/h"}],"children":[]},"s1":{"type":"Stat","props":{"tone":"brand","label":"O removed","value":{"args":{"c":{"$state":"/c"},"h":{"$state":"/h"},"expr":"min(c + h, 6)","digits":0},"$computed":"calc"}},"children":[]},"s2":{"type":"Stat","props":{"tone":"warning","label":"O still on the iron","value":{"args":{"c":{"$state":"/c"},"h":{"$state":"/h"},"expr":"6 - min(c + h, 6)","digits":0},"$computed":"calc"}},"children":[]},"row":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["s1","s2"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","a","b","row","ok"]}}},"title":"Share the oxygen"},{"id":"s5","kind":"example","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"t":{"type":"Text","props":{"content":"The reducing gases are given. Fill in the iron oxide and the iron."},"children":[]},"eb":{"type":"EquationBuilder","props":{"prompt":"Complete the Midrex reduction equation.","answers":[2,4],"template":"\\ce{{?}Fe2O3(s) + 3CO(g) + 3H2(g) -> {?}Fe(s) + 3CO2(g) + 3H2O(v)}","conditions":"Δ"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","eb","h"]}}},"title":"Balance it"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Raw material","coke","natural gas (93% methane)"],["Reducing agent","CO","CO + H₂ (water gas)"],["Gases formed","CO₂","CO₂ + H₂O"]],"headers":["","Blast furnace","Midrex furnace"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tb","m"]}}},"title":"Blast furnace vs Midrex"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"New case: $\\ce{NiO + H2 ->[\\Delta] Ni + H2O}$. The reducing agent is ___.","answers":[["h2","hydrogen"]],"mistakes":[{"id":"m1","blank":0,"answer":"h2o"},{"id":"m2","blank":0,"answer":"nio"},{"id":"m3","blank":0,"answer":"ni"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Methane reduces $\\ce{Fe2O3}$ directly to iron.","correct":false},{"id":"b","text":"It is the source of water gas (CO + $\\ce{H2}$), which reduces the iron oxide.","correct":true},{"id":"c","text":"It burns coke to make CO.","correct":false},{"id":"d","text":"It dries the ore and expels humidity.","correct":false}],"question":"Exam question: \"Explain the role of natural gas in the Midrex furnace.\" Which answer gets full marks?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"The Midrex furnace uses coke as its source of carbon monoxide."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","f","tf"]}}},"title":"Check yourself"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["$\\ce{2CH4 + CO2 + H2O -> 3CO + 5H2}$ (water gas).","$\\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$.","Blast furnace: CO from coke. Midrex: CO + H₂ from natural gas."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"Natural gas is changed into water gas, a mixture of CO and $\\ce{H2}$: $\\ce{2CH4 + CO2 + H2O -> 3CO + 5H2}$. Both gases take oxygen from the ore: $\\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain how the Midrex furnace reduces the ore with no coke?"},"children":[]}}},"title":"Summary"}],"title":"Reduction in the Midrex furnace","minutes":8,"book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (b), p.18; Evaluation Q5.2, p.26","subtitle":"Natural gas gives two reducing agents","objectives":["Write the equation that turns natural gas into water gas.","Write the reduction equation of the ore by CO and H₂.","Explain the role of natural gas and compare with the blast furnace."],"concept_ids":["fe.midrex-reduction"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Methane is the raw material: it is changed into other gases first, not used directly."},{"id":"b","feedback":"The Midrex furnace starts from natural gas instead of coke, so coke plays no part here."},{"id":"c","feedback":"Good thinking. Both gases can take oxygen from the ore."},{"id":"d","feedback":"The ore must lose oxygen, and adding oxygen works against that."}],"explanation":"In the Midrex furnace a mixture of CO and $\\ce{H2}$ (water gas), made from natural gas, reduces the iron oxide. Methane is changed into these gases first, no coke is used, and oxygen would add oxygen instead of removing it."}},"s4":{"ok":{"body":"This is the book's mix: 3CO + 3H₂ remove all 6 O atoms."}},"s5":{"h":{"hints":["Count the O atoms taken by 3CO and 3H₂.","Each $\\ce{Fe2O3}$ gives 3 O atoms. How many $\\ce{Fe2O3}$ give that many?"]},"eb":{"explanation":"6 O are removed: 3 by CO and 3 by H₂. That is 2 Fe₂O₃, giving 4 Fe."}},"s6":{"m":{"statement":"Methane reduces the ore.","correction":"In the book's equations $\\ce{CH4}$ never meets $\\ce{Fe2O3}$: natural gas is the source of CO and $\\ce{H2}$, which reduce the ore. And Midrex uses no coke."}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"That is a product; the reducing agent is the reactant that gains oxygen."},{"id":"m2","feedback":"This reactant loses oxygen, so it is reduced; the reducing agent is the reactant that takes its oxygen."},{"id":"m3","feedback":"That is a product; the reducing agent is the reactant that gains oxygen."}],"explanation":"$\\ce{H2}$ gains oxygen to become $\\ce{H2O}$: it is the reducing agent."},"q":{"options":[{"id":"a","feedback":"$\\ce{CH4}$ is not among the reactants of the reduction equation, $\\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$: methane is changed first, and the gases it gives take the oxygen from the ore."},{"id":"b","feedback":"Right. Natural gas gives the two reducing agents."},{"id":"c","feedback":"No coke is used in the Midrex furnace at all."},{"id":"d","feedback":"Drying the ore is a purpose of roasting, an earlier stage, not of the Midrex furnace."}],"explanation":"Natural gas (93% methane) is the source of water gas, CO + $\\ce{H2}$: $\\ce{2CH4 + CO2 + H2O -> 3CO + 5H2}$. These two gases reduce the iron oxide: $\\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$."},"tf":{"explanation":"The statement is false: the Midrex furnace uses no coke. Its CO comes from natural gas, together with $\\ce{H2}$.","feedback_true":"The Midrex furnace uses no coke: its CO comes from natural gas, $\\ce{2CH4 + CO2 + H2O -> 3CO + 5H2}$, and no solid carbon appears in its equations.","feedback_false":"Right. Its CO comes from natural gas."}},"s8":{"e":{"body":"Role of natural gas: \"a source of the reducing mixture of carbon monoxide and hydrogen (water gas)\"."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ methane ده المادة الخام: بيتحوّل الأول لغازات تانية، ومش هو اللي بيعمل reduction مباشرة."},{"id":"b","feedback":"الـ Midrex furnace بيبدأ من الـ natural gas بدل الـ coke، ومفيش coke بيُستخدم فيه."},{"id":"c","feedback":"تفكير حلو. الغازين الاتنين يقدروا ياخدوا الـ oxygen من الـ ore."},{"id":"d","feedback":"الـ ore لازم يخسر oxygen، وإننا نزوّد oxygen بيعمل العكس."}],"explanation":"في الـ Midrex furnace، خليط من الـ CO والـ $\\ce{H2}$ (الـ water gas) جاي من الـ natural gas هو اللي بيعمل reduction للـ iron oxide. الـ methane بيتحوّل للغازين دول الأول، ومفيش coke بيُستخدم، والـ oxygen هيزوّد oxygen بدل ما يشيله."}},"s4":{"ok":{"body":"ده الخليط اللي في الكتاب: 3CO + 3H₂ بيشيلوا الـ 6 ذرات O كلهم."}},"s5":{"h":{"hints":["عدّ ذرات الـ O اللي بياخدها الـ 3CO والـ 3H₂.","كل $\\ce{Fe2O3}$ بيدّي 3 ذرات O. طب محتاج كام $\\ce{Fe2O3}$ عشان يدّوا العدد ده؟"]},"eb":{"explanation":"بيتشال 6 O: الـ CO بياخد 3 والـ H₂ بياخد 3. يعني 2 Fe₂O₃، وده بيدّي 4 Fe."}},"s6":{"m":{"statement":"الـ methane هو اللي بيعمل reduction للـ ore.","correction":"في معادلات الكتاب الـ $\\ce{CH4}$ عمره ما بيقابل الـ $\\ce{Fe2O3}$: الـ natural gas هو مصدر الـ CO والـ $\\ce{H2}$، ودول اللي بيعملوا reduction للـ ore. وكمان الـ Midrex مفيهوش coke خالص."}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"ده product، والـ reducing agent بيبقى reactant بياخد oxygen."},{"id":"m2","feedback":"الـ reactant ده بيخسر oxygen، يعني هو اللي بيحصله reduction، مش هو اللي بياخد الـ oxygen."},{"id":"m3","feedback":"ده product، والـ reducing agent بيبقى reactant بياخد oxygen."}],"explanation":"الـ $\\ce{H2}$ بياخد oxygen ويبقى $\\ce{H2O}$: يبقى هو الـ reducing agent."},"q":{"options":[{"id":"a","feedback":"الـ $\\ce{CH4}$ مش من ضمن الـ reactants في معادلة الـ reduction، $\\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$: الـ methane بيتحوّل الأول، والغازات اللي بتطلع منه هي اللي بتاخد الـ oxygen من الـ ore."},{"id":"b","feedback":"صح. الـ natural gas بيدّينا الاتنين reducing agents."},{"id":"c","feedback":"الـ Midrex furnace مش بيستخدم coke أصلًا."},{"id":"d","feedback":"ده هدف من أهداف الـ roasting، ودي مرحلة قبل الـ Midrex furnace، مش دور الـ natural gas فيه."}],"explanation":"الـ natural gas (93% methane) هو مصدر الـ water gas، يعني CO + $\\ce{H2}$: $\\ce{2CH4 + CO2 + H2O -> 3CO + 5H2}$. والغازين دول هما اللي بيعملوا reduction للـ iron oxide: $\\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$."},"tf":{"explanation":"الجملة دي false: الـ Midrex furnace مش بيستخدم coke. الـ CO بتاعه جاي من الـ natural gas، ومعاه $\\ce{H2}$.","feedback_true":"الـ Midrex furnace مش بيستخدم coke: الـ CO بتاعه جاي من الـ natural gas، $\\ce{2CH4 + CO2 + H2O -> 3CO + 5H2}$، ومفيش carbon صلب في معادلاته.","feedback_false":"صح. الـ CO بتاعه جاي من الـ natural gas."}},"s8":{"e":{"body":"دور الـ natural gas في الامتحان: \"a source of the reducing mixture of carbon monoxide and hydrogen (water gas)\"."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":6,"lesson_no":13,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-extraction","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron ores and extraction of iron","duration_s":734.029,"start_s":498.7,"end_s":570.6,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.midrex-reduction","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Reduction in the Midrex furnace","duration_s":45.75,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q5","section_title":"Explain the role","section_path":["Transition Elements","Evaluation","Explain the role"],"exercise":"Question 5","question":"2","relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.steel-production","kind":"lesson","version":2,"catalog_version":3,"ord":363,"primary_concept_id":"fe.steel-production","concepts":[{"concept_id":"fe.steel-production","role":"primary"}],"title":"Iron production and steel","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Pure iron","correct":false},{"id":"b","text":"Iron exactly as it leaves the blast furnace","correct":false},{"id":"c","text":"Iron, cleaned of impurities, with some elements added","correct":true},{"id":"d","text":"A metal different from iron","correct":false}],"question":"Predict: what is steel?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Car bodies, bridges and many tools are made of steel. Yet the furnaces you met so far give iron, not steel."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Is steel just iron?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"FlowDiagram","props":{"edges":[{"to":"r","from":"d"},{"to":"p","from":"r"}],"nodes":[{"id":"d","label":"Ore dressing"},{"id":"r","label":"Reduction of iron ores"},{"id":"p","label":"Iron production"}],"caption":"Extraction of iron from its ores: three stages (book p.17-18)"},"children":[]},"t":{"type":"Text","props":{"content":"After the reduction of iron ores in the blast furnace or Midrex furnace comes the third step: iron production."},"children":[]},"t2":{"type":"Text","props":{"content":"It produces different types of iron, such as cast iron and steel."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","t2"]}}},"title":"The third stage"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Removal of impurities from iron resulting from the furnaces.","Addition of some elements to iron to produce steel with the required properties for industrial purposes."],"ordered":true},"children":[]},"g":{"type":"Callout","props":{"variant":"info"},"children":[]},"t":{"type":"Text","props":{"content":"The steel industry depends on two essential processes:"},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"r","from":"i"},{"to":"a","from":"r"},{"to":"s","from":"a"}],"nodes":[{"id":"i","label":"Iron from the furnaces"},{"id":"r","label":"Removal of impurities"},{"id":"a","label":"Addition of some elements"},{"id":"s","label":"Steel"}],"layout":"horizontal"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","b","fl","g"]}}},"title":"Two essential processes"},{"id":"s4","kind":"interact","spec":{"root":"root","elements":{"o":{"type":"Ordering","props":{"items":[{"id":"a","text":"Roasting the ore in air"},{"id":"b","text":"Reducing the ore with CO (or CO + H₂)"},{"id":"c","text":"Removing impurities from the furnace iron"},{"id":"d","text":"Adding some elements to give the required properties"}],"prompt":"Put the steps in order, from ore to steel."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["o"]}}},"title":"From ore to steel"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Callout","props":{"variant":"tip"},"children":[]},"t":{"type":"Text","props":{"content":"Steel is produced by one of three furnaces: the oxygen converters, the open-hearth furnace or the electric furnace."},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"a","from":"i"},{"to":"b","from":"i"},{"to":"c","from":"i"},{"to":"s","from":"a"},{"to":"s","from":"b"},{"to":"s","from":"c"}],"nodes":[{"id":"i","label":"Iron from the furnaces"},{"id":"a","label":"Oxygen converter"},{"id":"b","label":"Open-hearth furnace"},{"id":"c","label":"Electric furnace"},{"id":"s","label":"Steel"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fl","t","c"]}}},"title":"Steel furnaces"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"m2":{"type":"Misconception","props":{},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Made in","Blast furnace or Midrex furnace","Oxygen converter, open-hearth furnace or electric furnace"],["Made from","Iron ore","Iron from the furnaces: impurities removed, some elements added"]],"headers":["","Iron from the furnaces","Steel"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["m","m2","tb"]}}},"title":"Two mix-ups"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Yes: steel is iron with the impurities removed.","correct":false},{"id":"b","text":"No: steel also needs some elements added for the required properties.","correct":true},{"id":"c","text":"Yes, if it was done in the blast furnace.","correct":false}],"question":"A student removes every impurity from furnace iron and adds nothing. Has the student made steel?"},"children":[]},"cl":{"type":"Classify","props":{"items":[{"id":"i1","text":"Blast furnace"},{"id":"i2","text":"Electric furnace"},{"id":"i3","text":"Midrex furnace"},{"id":"i4","text":"Open-hearth furnace"},{"id":"i5","text":"Oxygen converter"}],"answer":{"st":["i2","i4","i5"],"red":["i1","i3"]},"prompt":"Which job does each furnace do?","categories":[{"id":"red","label":"Reduces iron ore to iron"},{"id":"st","label":"Produces steel from iron"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["cl","q"]}}},"title":"Check yourself"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Third stage: production of different types of iron, such as cast iron and steel.","Steel: removal of impurities from furnace iron + addition of some elements.","Steel furnaces: oxygen converters, open-hearth furnace, electric furnace."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"The iron from the blast furnace still holds impurities. Steel is made from it in a steel furnace: the impurities are removed, then some elements are added to give the required properties."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why steel is not the same as the iron from the blast furnace?"},"children":[]}}},"title":"Summary"}],"title":"Iron production and steel","minutes":6,"book_ref":"Ch.1 'Thirdly: Iron Production' and 'Steel', p.18","subtitle":"From furnace iron to steel","objectives":["State that the third stage produces types of iron such as cast iron and steel.","Name the two essential processes of the steel industry.","Name the three furnaces used to produce steel."],"concept_ids":["fe.steel-production"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"A common idea, but steel makers add elements on purpose, so steel is not pure."},{"id":"b","feedback":"That iron still holds impurities, and it is treated before it becomes steel."},{"id":"c","feedback":"Good thinking. Both steps matter."},{"id":"d","feedback":"Steel is made from iron, not from a different metal."}],"explanation":"Steel is made from the iron that leaves the furnaces by two processes: removal of impurities, and addition of some elements to give the required properties."}},"s3":{"g":{"body":"So steel is iron with chosen elements, such as carbon. Steel is an alloy: a metal mixed with other elements. You will study alloys next."}},"s4":{"o":{"items":[{"id":"a","feedback":"Roasting works on the ore, before any iron metal exists."},{"id":"b","feedback":"Reduction turns ore into iron, and the steel steps need that iron to exist already."},{"id":"c","feedback":"These impurities are in the iron that comes from reducing the ore."},{"id":"d","feedback":"Added elements would not survive a later step that removes impurities."}],"explanation":"Ore dressing (roasting), reduction, then the two steel processes: removal of impurities, then addition of elements."}},"s5":{"c":{"body":"The book names these furnaces only. Learn the three names."}},"s6":{"m":{"statement":"Steel is pure iron.","correction":"Steel making adds elements to iron on purpose, such as carbon. Pure iron has nothing added."},"m2":{"statement":"Steel comes straight out of the blast furnace.","correction":"The blast furnace or Midrex furnace gives iron. Steel is made from it later, in steel furnaces."}},"s7":{"q":{"options":[{"id":"a","feedback":"Removing impurities is only one of the two processes of the steel industry."},{"id":"b","feedback":"Right. Removal of impurities plus addition of some elements."},{"id":"c","feedback":"The blast furnace reduces the ore; it does not make steel."}],"explanation":"Removal of impurities is one of the two processes. Steel also needs some elements added to give the required properties for industrial purposes."},"cl":{"items":[{"id":"i1","feedback":"The blast furnace starts from iron ore."},{"id":"i2","feedback":"The electric furnace starts from iron, not from ore."},{"id":"i3","feedback":"The Midrex furnace starts from iron ore."},{"id":"i4","feedback":"The open-hearth furnace starts from iron, not from ore."},{"id":"i5","feedback":"The oxygen converter starts from iron, not from ore."}],"explanation":"Blast and Midrex furnaces reduce the ore. Oxygen converters, open-hearth and electric furnaces make steel."}},"s8":{"e":{"body":"\"The steel industry depends on two essential processes\": write both, in the book's words."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"فكرة منتشرة، لكن اللي بيصنعوا الـ steel بيضيفوا عناصر بقصد، فمينفعش يفضل نقي."},{"id":"b","feedback":"الـ iron ده لسه فيه شوائب، ولسه بيتعمل فيه شغل قبل ما يبقى steel."},{"id":"c","feedback":"تفكير حلو. الخطوتين الاتنين مهمين."},{"id":"d","feedback":"الـ steel معمول من الـ iron نفسه، مش من metal تاني."}],"explanation":"الـ steel بيتعمل من الـ iron اللي طالع من الأفران بعمليتين: شيل الشوائب، وإضافة بعض العناصر عشان ياخد الخواص المطلوبة."}},"s3":{"g":{"body":"يعني الـ steel هو iron متضاف له عناصر متختارة، زي الـ carbon. والـ steel يعتبر alloy: metal متخلط بعناصر تانية. هتدرس الـ alloys بعد كده."}},"s4":{"o":{"items":[{"id":"a","feedback":"الـ roasting بيشتغل على الـ ore نفسه، وساعتها لسه مفيش iron metal."},{"id":"b","feedback":"الـ reduction هو اللي بيحوّل الـ ore لـ iron، وخطوات الـ steel محتاجة إن الـ iron يكون موجود قبلها."},{"id":"c","feedback":"الشوائب دي بتتشال من الـ iron اللي طالع من الفرن، والـ iron ده بييجي من الـ reduction."},{"id":"d","feedback":"لو جت بعد الإضافة خطوة بتشيل الشوائب، ممكن تشيل معاها العناصر اللي اتضافت."}],"explanation":"الـ ore dressing (الـ roasting)، وبعده الـ reduction، وبعدين عمليتين الـ steel: شيل الشوائب الأول، وبعدها إضافة العناصر."}},"s5":{"c":{"body":"الكتاب مش بيذكر عن الأفران دي غير أساميها. احفظ الأسامي التلاتة."}},"s6":{"m":{"statement":"الـ steel هو iron نقي.","correction":"صناعة الـ steel بتضيف عناصر للـ iron بقصد، زي الـ carbon. أما الـ iron النقي فمفيش حاجة متضافة له."},"m2":{"statement":"الـ steel بيطلع على طول من الـ blast furnace.","correction":"الـ blast furnace أو الـ Midrex furnace بيدّوا iron، والـ steel بيتعمل من الـ iron ده بعد كده في أفران الـ steel."}},"s7":{"q":{"options":[{"id":"a","feedback":"دي عملية واحدة من الاتنين، وصناعة الـ steel فيها خطوة تانية غير شيل الشوائب."},{"id":"b","feedback":"صح. شيل الشوائب + إضافة بعض العناصر."},{"id":"c","feedback":"الـ blast furnace بيعمل reduction للـ ore، ومش هو الفرن اللي بيعمل steel."}],"explanation":"شيل الشوائب عملية واحدة من الاتنين. الـ steel محتاج كمان إضافة بعض العناصر عشان ياخد الخواص المطلوبة للاستخدامات الصناعية."},"cl":{"items":[{"id":"i1","feedback":"الـ blast furnace بيبدأ من الـ iron ore، مش من iron جاهز."},{"id":"i2","feedback":"الفرن ده بيبدأ من iron جاهز، مش من الـ iron ore."},{"id":"i3","feedback":"الـ Midrex furnace بيبدأ من الـ iron ore، مش من iron جاهز."},{"id":"i4","feedback":"الفرن ده بيبدأ من iron جاهز، مش من الـ iron ore."},{"id":"i5","feedback":"الفرن ده بيبدأ من iron جاهز، مش من الـ iron ore."}],"explanation":"الـ blast furnace والـ Midrex furnace بيعملوا reduction للـ ore. والـ oxygen converters والـ open-hearth furnace والـ electric furnace بيعملوا steel."}},"s8":{"e":{"body":"\"The steel industry depends on two essential processes\": اكتب العمليتين الاتنين بكلام الكتاب نفسه."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":7,"lesson_no":14,"lesson_count":14,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-extraction","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron ores and extraction of iron","duration_s":734.029,"start_s":577.7,"end_s":642.8,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.steel-production","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Iron production and steel","duration_s":56.5,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.production","section_title":"Iron Production 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Its ions are free to move to the plates."},{"id":"c","feedback":"Sugar does not form ions in water, so nothing carries the charge."}],"explanation":"Sodium chloride solution carries a current because its ions are free to move to the plates. In solid salt the ions cannot move, and sugar does not form ions in water."},"fb":{"mistakes":[{"id":"m1","feedback":"Protons sit in the nucleus and stay in place; the moving charges are the particles that form the 'sea' in a metal."},{"id":"m2","feedback":"In a wire, the metal ions stay in their places; smaller particles move freely between them."}],"explanation":"In a metal wire, the metal ions stay in their places and the free electrons move between them, so the moving charges are free electrons."},"tf":{"explanation":"Unlike charges attract and like charges repel, so positive ions move towards the plate joined to the negative terminal, away from the positive plate.","feedback_true":"Two positive charges repel each other, so positive ions move away from the positive plate.","feedback_false":"Right. Positive ions are attracted to the negative plate."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"البطارية مفيهاش مشكلة، لكن الـ charges مش بتقدر تعدّي فجوة هوا في السلك."},{"id":"b","feedback":"أيوه. الـ charges محتاجة مسار كامل مقفول. تعالى نشوف ليه."},{"id":"c","feedback":"النور الأضعف معناه سريان أقل، لكن مع وجود فجوة الـ charges مش بتقدر تسري أصلًا."}],"explanation":"الـ charges بتسري في مسار كامل مقفول. لما السلك يتقطع بتبقى فيه فجوة هوا الـ charges مش بتقدر تعدّيها، فالـ current بيقف واللمبة بتطفي."}},"s4":{"q":{"options":[{"id":"a","feedback":"الملح متكوّن من ions، لكن وهو صلب الـ ions دي مش بتقدر تتحرك."},{"id":"b","feedback":"صح. الـ ions بتاعته حرة إنها تتحرك ناحية الألواح."},{"id":"c","feedback":"السكر مش بيكوّن ions في المية، فمفيش حاجة في الـ solution تشيل الـ charge."}],"explanation":"الـ sodium chloride solution بيوصّل الـ current عشان الـ ions بتاعته حرة تتحرك ناحية الألواح. في الملح الصلب الـ ions مش بتقدر تتحرك، والسكر مش بيكوّن ions في المية."},"fb":{"mistakes":[{"id":"m1","feedback":"الـ protons قاعدة في الـ nucleus وثابتة مكانها، فمش هي اللي بتعمل 'البحر' اللي جوه الـ metal."},{"id":"m2","feedback":"في السلك، الـ metal ions ثابتة في أماكنها، واللي بيتحرك بحرية بينهم جسيمات أصغر منها."}],"explanation":"في سلك الـ metal، الـ metal ions بتفضل ثابتة في أماكنها والـ free electrons هي اللي بتتحرك بينهم، فالـ charges اللي بتتحرك هي الـ free electrons."},"tf":{"explanation":"الـ charges المختلفة بتتجاذب والـ like charges بتتنافر، فالـ positive ions بتتحرك ناحية اللوح المتوصّل بالـ negative terminal، بعيد عن اللوح الـ positive.","feedback_true":"اتنين positive charges بيتنافروا، فالـ positive ions بتبعد عن اللوح الـ positive.","feedback_false":"صح. الـ positive ions بتنجذب للوح الـ negative."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":1,"is_basics":true,"lesson_no":1,"lesson_count":6,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-phys.electric-current","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Electric current: from zero","duration_s":276.5,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-phys.electric-current","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Electric current","duration_s":46.07,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.preparation","section_title":"Preparation of alloys","section_path":["Transition Elements","Alloys","Preparation of alloys"],"relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":66,"page_to":66,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":84,"page_to":84,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.electroplating-basic","kind":"lesson","version":3,"catalog_version":3,"ord":411,"primary_concept_id":"chem.electroplating-basic","concepts":[{"concept_id":"chem.electroplating-basic","role":"primary"}],"title":"Electroplating","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Copper ions in the solution became copper metal on the key","correct":true},{"id":"b","text":"The iron of the key changed into copper","correct":false},{"id":"c","text":"Copper dust in the liquid stuck to the key","correct":false}],"question":"Predict: where did the copper coat come from?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"An iron key hangs in a solution of copper ions. 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grows</text></svg>","max_width":380},"visible":{"eq":3,"$state":"/t"},"children":[]},"sl":{"type":"Slider","props":{"max":3,"min":1,"step":1,"label":"Time (stage)","value":{"$bindState":"/t"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","sl","d1","d2","d3","f","t"]}}},"title":"At the cathode"},{"id":"s4","kind":"interact","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"The coat is made of the metal whose ions are in the solution."},"children":[]},"cl":{"type":"Classify","props":{"items":[{"id":"i1","text":"Object joined to −, in a solution of nickel ions"},{"id":"i2","text":"Object joined to +, in a solution of nickel ions"},{"id":"i3","text":"Object joined to −, in a sugar solution"},{"id":"i4","text":"Object joined to −, in a solution of zinc ions"}],"answer":{"no":["i2","i3"],"yes":["i1","i4"]},"prompt":"Does the object get a metal coat?","categories":[{"id":"yes","label":"Gets a metal coat"},{"id":"no","label":"Gets no coat"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["m","t","cl"]}}},"title":"Coat or no coat?"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Spoon joined to −, in a solution of silver ions","correct":true},{"id":"b","text":"Spoon joined to +, in a solution of silver ions","correct":false},{"id":"c","text":"Spoon joined to −, in a solution of copper ions","correct":false},{"id":"d","text":"Spoon joined to −, in a sugar solution","correct":false}],"question":"You want to coat a spoon with silver. Which setup works?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"In electroplating, the object to be coated is joined to the ___ terminal of the battery.","answers":[["negative"]],"mistakes":[{"id":"m1","blank":0,"answer":"positive"}]},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"In electroplating, the metal ions lose electrons at the object."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","fb","tf"]}}},"title":"Check yourself"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Electroplating: a current through a solution of metal ions coats an object with that metal.","In electroplating, the object is the cathode: it is joined to the negative terminal.","At the cathode, metal ions gain electrons (reduction) and become atoms."]},"children":[]},"n":{"type":"Text","props":{"muted":true,"content":"Next: with ions of two metals, both deposit at once. 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By electro deposition, p.19 (taught fully in Ch.4, Electrochemistry)","subtitle":"A current turns metal ions into a metal coat","objectives":["Describe electroplating: a current through a solution of metal ions coats an object with that metal.","Explain why, in electroplating, the object to be coated is the cathode, joined to the negative terminal.","Predict the metal of the coat from the ions in the solution."],"concept_ids":["chem.electroplating-basic"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. The current drives the ions there. Let's see how."},{"id":"b","feedback":"One element cannot change into another in a reaction, so the iron of the key cannot become copper."},{"id":"c","feedback":"The solution holds copper ions, not copper dust."}],"explanation":"The copper coat came from the copper ions in the solution: the current drove them to the key, where they gained electrons and became copper metal."}},"s4":{"m":{"statement":"The object goes on the positive terminal.","correction":"Metal ions are positive, so a positive plate pushes them away. 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The metal ions are positive, so they are attracted to it and deposit on it as metal."},"tf":{"explanation":"At the object, the metal ions gain electrons: $\\ce{Cu^2+}$ gains 2 electrons and becomes a neutral Cu atom.","feedback_true":"Count the charges: $\\ce{Cu^2+}$ ends as Cu, a neutral atom, so it gains electrons.","feedback_false":"Right. The ions gain electrons and become metal atoms."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. الـ current هو اللي بيسوق الـ ions لهناك. تعالى نشوف إزاي."},{"id":"b","feedback":"مفيش element يقدر يتحوّل لـ element تاني في تفاعل، فالـ iron بتاع المفتاح مش هو اللي بقى copper."},{"id":"c","feedback":"الـ solution فيه copper ions، مش تراب copper، فمفيش تراب يلزق في المفتاح."}],"explanation":"طبقة الـ copper جاية من الـ copper ions اللي في الـ solution: الـ current ساقها ناحية المفتاح، وهناك كسبت electrons واتحوّلت لـ copper metal."}},"s4":{"m":{"statement":"الجسم بيتوصّل بالـ positive terminal.","correction":"الـ metal ions positive، فاللوح الـ positive بيزقها بعيد. عشان كده الجسم بيتوصّل بالـ negative terminal اللي بيشدها ناحيته."},"cl":{"items":[{"id":"i1","feedback":"الجسم متوصّل بالـ −، والـ nickel ions positive فبتتجذب ليه."},{"id":"i2","feedback":"الـ nickel ions positive، واللوح الـ positive بيزقها بعيد مش بيشدها."},{"id":"i3","feedback":"الـ sugar solution مافيهوش أي metal ions."},{"id":"i4","feedback":"الـ zinc ions positive، والجسم متوصّل بالـ − اللي بيشدها ناحيته."}],"explanation":"عشان تتكوّن طبقة، لازم يكون فيه metal ions في الـ solution، والجسم يكون متوصّل بالـ negative terminal."}},"s5":{"q":{"options":[{"id":"a","feedback":"صح. الـ silver ions الـ positive بتتحرك ناحية المعلقة وبتكسب electrons هناك."},{"id":"b","feedback":"الـ silver ions positive، واللوح الـ + بيزقها بعيد عن المعلقة."},{"id":"c","feedback":"الطبقة بتتكوّن من الـ ions اللي في الـ solution، فهنا اللي هيترسّب copper مش silver."},{"id":"d","feedback":"الـ sugar solution مفيهوش metal ions، فمفيش حاجة تكوّن الطبقة."}],"explanation":"عشان تغطي معلقة بالـ silver، المعلقة بتتوصّل بالـ − وتتحط في solution فيه silver ions: الـ silver ions الـ positive بتتحرك ناحية المعلقة، وبتكسب electrons وتترسّب silver."},"fb":{"mistakes":[{"id":"m1","feedback":"الـ metal ions positive، والـ positive terminal بيزق الـ positive charges بعيد مش بيشدها."}],"explanation":"الحاجة اللي عايزين نغطيها بتتوصّل بالـ negative terminal. الـ metal ions positive، فبتتجذب ليها وبتترسّب عليها كـ metal."},"tf":{"explanation":"عند الحاجة اللي بتتغطّى، الـ metal ions بتكسب electrons: الـ $\\ce{Cu^2+}$ بيكسب 2 electrons ويبقى Cu atom متعادل.","feedback_true":"عدّ الـ charges: الـ $\\ce{Cu^2+}$ آخره Cu، atom متعادل، وده معناه إنه كسب electrons مش خسرهم.","feedback_false":"صح. الـ ions بتكسب electrons وبتتحوّل لـ metal atoms."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":2,"is_basics":true,"lesson_no":2,"lesson_count":6,"lesson_video":{"item_id":"chem-s3-en.video-episode-alloys","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Alloys and their 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Careful: some are not alloys at all."},"children":[]},"cl":{"type":"Classify","props":{"items":[{"id":"i1","text":"Copper and tin are melted together, then left to cool gradually."},{"id":"i2","text":"A current deposits nickel and iron at the same time from a solution of their ions."},{"id":"i3","text":"Aluminum and manganese are melted together, then cooled gradually."},{"id":"i4","text":"A key is coated from a solution of copper ions only."},{"id":"i5","text":"Zinc is melted on its own and poured into a mould."}],"answer":{"ed":["i2"],"melt":["i1","i3"],"none":["i4","i5"]},"prompt":"How is each product made?","categories":[{"id":"melt","label":"Alloy by melting"},{"id":"ed","label":"Alloy by electro-deposition"},{"id":"none","label":"Not an alloy"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","cl"]}}},"title":"Sort the methods"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"No: an alloy may consist of a metal and a non-metal","correct":true},{"id":"b","text":"Yes: alloys contain metals only","correct":false},{"id":"c","text":"Yes: a metal and a non-metal always form a compound","correct":false}],"question":"Metal X is mixed with a little of non-metal Y in one solid. A student says: \"Y is a non-metal, so this cannot be an alloy.\" Is the student right?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"By melting: the metals are melted together and left to cool ___. By electro-deposition: two metals or more deposit at the same ___.","answers":[["gradually","slowly"],["time"]],"mistakes":[{"id":"m1","blank":0,"answer":"quickly"},{"id":"m2","blank":0,"answer":"fast"},{"id":"m3","blank":1,"answer":"place"}]},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Every alloy is a chemical compound of its elements."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf","fb"]}}},"title":"Check yourself"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Alloy: usually two metals or more, or a metal with a non-metal (steel).","By melting: melt the metals together, then leave them to cool gradually.","By electro-deposition: two metals or more deposit at the same time.","An alloy is not always a compound."]},"children":[]},"r":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Show the answer"}},"children":["ra"]},"ex":{"type":"Callout","props":{"variant":"exam"},"children":[]},"ra":{"type":"Text","props":{"content":"Steel is iron with carbon. An alloy is usually formed from two metals or more, but it may consist of a metal and a non-metal, such as carbon in steel."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","ex","self","r"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why steel is an alloy, though carbon is not a metal?"},"children":[]}}},"title":"Summary"}],"title":"Alloys: definition and preparation","minutes":8,"book_ref":"Ch.1 'ALLOYS' and 'Preparation of alloys', p.19; alloy uses, p.6-8","subtitle":"Two metals or more, or a metal with a non-metal; made by melting or by electro-deposition","objectives":["State the book's definition of an alloy, with metal-metal and metal-non-metal examples.","Describe preparation by melting: melt the metals together, then leave them to cool gradually.","Describe preparation by electro-deposition of two or more metals at the same time.","Recognize that an alloy may contain a non-metal and is not always a chemical compound."],"concept_ids":["alloy.definition-preparation"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Iron and manganese are both metals, so ferromanganese has no non-metal in it."},{"id":"b","feedback":"Yes. Steel is iron with carbon, a non-metal. And it is still an alloy."},{"id":"c","feedback":"Ferro- means iron, and manganese is a metal too, so ferromanganese has no non-metal in it."},{"id":"d","feedback":"An alloy can contain a non-metal: one of these two materials is iron with a non-metal added, and it is still an alloy."}],"explanation":"Steel contains a non-metal: it is iron with carbon, and it is still an alloy. Ferromanganese is iron with manganese, two metals."}},"s3":{"m":{"statement":"Every alloy is a chemical compound.","correction":"The book lists three types of alloy. In two of them, the atoms are only mixed in one solid; only in the third do the elements combine chemically."}},"s6":{"cl":{"items":[{"id":"i1","feedback":"No current is used here: heat mixes the two metals as liquids."},{"id":"i2","feedback":"Nothing is melted here: the current deposits the two metals from their ions together."},{"id":"i3","feedback":"No current is used here: heat mixes these two metals as liquids."},{"id":"i4","feedback":"Only one metal deposits on the key, and an alloy needs two elements or more."},{"id":"i5","feedback":"Zinc is the one metal in the melt, and an alloy needs two elements or more."}],"explanation":"An alloy needs two elements or more. Melting mixes them as liquids; electro-deposition deposits them together."}},"s7":{"q":{"options":[{"id":"a","feedback":"Right. Steel, iron with carbon, is the book's example."},{"id":"b","feedback":"Steel is an alloy, and its carbon is not a metal."},{"id":"c","feedback":"Not every alloy is a compound: in two of the book's three types, the elements do not combine chemically."}],"explanation":"An alloy may consist of a metal and a non-metal, so a non-metal in it does not rule out an alloy. Steel, iron with carbon, is the book's example."},"fb":{"mistakes":[{"id":"m1","feedback":"The book's wording does not describe fast cooling for this method."},{"id":"m2","feedback":"The book's wording does not describe fast cooling for this method."},{"id":"m3","feedback":"They do deposit on one object, but the book stresses that they deposit together, not one after the other."}],"explanation":"By melting, the metals are melted together and left to cool gradually. By electro-deposition, two metals or more deposit at the same time, as when iron handles are coated with brass (Cu + Zn)."},"tf":{"explanation":"Of the book's three types, the elements combine chemically into a compound in intermetallic alloys. In interstitial and substitutional alloys, the atoms are mixed in one solid without forming a compound.","feedback_true":"In only one of the book's three types do the elements combine chemically into a compound.","feedback_false":"Right. In two types, the atoms are only mixed in one solid."}},"s8":{"ex":{"body":"Exams ask for the two methods of preparing alloys. Answer: by melting, and by electro-deposition (brass on iron handles)."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ iron والـ manganese الاتنين metals، فالـ ferromanganese مافيهوش non-metal."},{"id":"b","feedback":"أيوه. الـ steel هو iron مع carbon، والـ carbon ده non-metal. ومع كده لسه alloy."},{"id":"c","feedback":"Ferro- معناها iron، والـ manganese ده metal، فالـ ferromanganese كله metals ومافيهوش non-metal."},{"id":"d","feedback":"الـ alloys مش لازم تكون metals بس: ممكن يبقى فيها non-metal زي الـ carbon اللي بيتضاف للـ iron."}],"explanation":"الـ steel هو اللي فيه non-metal: هو iron مع carbon، ومع كده هو alloy. أما الـ ferromanganese فهو iron مع manganese، يعني اتنين metals."}},"s3":{"m":{"statement":"كل alloy هو chemical compound.","correction":"الكتاب فيه تلات أنواع من الـ alloys. في نوعين منهم الذرات مجرد متخلطة مع بعض في solid واحد، وفي النوع التالت تحديدًا العناصر بتتحد كيميائيًا."}},"s6":{"cl":{"items":[{"id":"i1","feedback":"هنا الـ metals اتصهرت مع بعض بالحرارة، ومفيش current."},{"id":"i2","feedback":"هنا مفيش حاجة اتصهرت: الـ current بيرسّب النوعين بتوع الـ ions مع بعض."},{"id":"i3","feedback":"هنا الحرارة هي اللي بتخلط الـ aluminum والـ manganese وهما سوايل، مش الـ current."},{"id":"i4","feedback":"metal واحد هو اللي بيترسّب على المفتاح، والـ alloy محتاج عنصرين على الأقل."},{"id":"i5","feedback":"فيه metal واحد في المصهور، والـ alloy محتاج عنصرين على الأقل."}],"explanation":"الـ alloy محتاج عنصرين أو أكتر. الـ melting بيخلطهم وهما سوايل، والـ electro-deposition بيرسّبهم مع بعض."}},"s7":{"q":{"options":[{"id":"a","feedback":"صح. الـ steel، اللي هو iron مع carbon، هو مثال الكتاب."},{"id":"b","feedback":"الـ steel فيه carbon، والـ carbon مش metal، ومع كده الـ steel ده alloy."},{"id":"c","feedback":"مش في كل alloy العناصر بتتحد كيميائيًا: من الأنواع التلاتة اللي في الكتاب، نوع واحد منهم هو اللي بيكوّن compound."}],"explanation":"الـ alloy ممكن يتكوّن من metal و non-metal، فوجود non-metal فيه مايمنعش إنه يبقى alloy. ومثال الكتاب هو الـ steel: iron مع carbon."},"fb":{"mistakes":[{"id":"m1","feedback":"الكتاب بيقول إن الـ metals بتتساب تبرد، والتبريد ده مش سريع."},{"id":"m2","feedback":"الكتاب بيقول إن الـ metals بتتساب تبرد، والتبريد ده مش سريع."},{"id":"m3","feedback":"هما فعلًا بيترسّبوا على نفس الحاجة، لكن الكتاب هنا بيركّز على إنهم بيترسّبوا مع بعض، مش واحد ورا التاني."}],"explanation":"في طريقة الصهر، الـ metals بتتصهر مع بعض وتتساب تبرد gradually (تدريجيًا). وفي الـ electro-deposition، اتنين metals أو أكتر بيترسّبوا at the same time (في نفس الوقت)، زي لما مقابض الـ iron بتتغطّى بالـ brass (Cu + Zn)."},"tf":{"explanation":"من الأنواع التلاتة اللي في الكتاب، العناصر بتتحد كيميائيًا وتكوّن compound في الـ intermetallic alloys. إنما في الـ interstitial والـ substitutional alloys، الذرات بتتخلط في جسم صلب واحد من غير ما تكوّن compound.","feedback_true":"من الأنواع التلاتة اللي في الكتاب، نوع واحد منهم هو اللي العناصر فيه بتتحد كيميائيًا. في النوعين التانيين الذرات بتتخلط من غير ما تكوّن compound.","feedback_false":"صح. في نوعين منهم، الذرات مجرد متخلطة مع بعض في جسم صلب واحد."}},"s8":{"ex":{"body":"الامتحانات بتسأل عن طريقتين تحضير الـ alloys. الإجابة: بالـ melting (الصهر)، وبالـ electro-deposition (زي تغطية مقابض الـ iron بالـ brass)."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":1,"lesson_no":3,"lesson_count":6,"lesson_video":{"item_id":"chem-s3-en.video-episode-alloys","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Alloys and their types","duration_s":599.729,"start_s":24.6,"end_s":181.6,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-alloy.definition-preparation","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Alloys: definition and 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2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-alloy.interstitial","kind":"lesson","version":4,"catalog_version":3,"ord":415,"primary_concept_id":"alloy.interstitial","concepts":[{"concept_id":"alloy.interstitial","role":"primary"}],"title":"Interstitial alloys","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It makes iron harder","correct":true},{"id":"b","text":"It makes iron softer","correct":false},{"id":"c","text":"Nothing: there is too little carbon","correct":false}],"question":"Predict: what does adding the small carbon atoms do to iron?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"The book says pure iron is relatively soft, so it has no industrial importance. Steel is iron with a little carbon."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Soft iron, hard steel"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -22 360 222\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"52\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"84\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"116\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"148\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"180\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"212\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"244\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"276\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"52\" cy=\"62\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"84\" cy=\"62\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"116\" cy=\"62\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"148\" cy=\"62\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"180\" cy=\"62\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"212\" cy=\"62\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"244\" cy=\"62\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"276\" cy=\"62\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"52\" cy=\"94\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"84\" cy=\"94\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"116\" cy=\"94\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"148\" cy=\"94\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"180\" cy=\"94\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"212\" cy=\"94\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"244\" cy=\"94\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"276\" cy=\"94\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"52\" cy=\"126\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"84\" cy=\"126\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"116\" cy=\"126\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"148\" cy=\"126\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"180\" cy=\"126\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"212\" cy=\"126\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"244\" cy=\"126\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"276\" cy=\"126\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><text x=\"180\" y=\"162\" font-size=\"13\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">fig 1-5 a: pure metal</text></svg>","max_width":360},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Crystal lattice","definition":"The regular arrangement of atoms in a solid. In a pure metal, the atoms are arranged in compact close rows."},"children":[]},"t":{"type":"Text","props":{"content":"Pure iron, like other metals, is built this way. All its atoms are the same size."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","d","t"]}}},"title":"Inside a pure metal"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"h":0},"elements":{"t":{"type":"Text","props":{"content":"Recall the metallic bond: layers of atoms can slide over each other. Try it."},"children":[]},"c1":{"type":"Text","props":{"content":"On hammering, a layer of metal atoms can slip over the other layers. The metal changes shape easily."},"visible":{"eq":1,"$state":"/h"},"children":[]},"d0":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -22 360 222\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"52\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"84\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"116\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"148\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"180\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"212\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"244\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" 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fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><line x1=\"20\" y1=\"46\" x2=\"340\" y2=\"46\" stroke=\"#fbbf24\" stroke-width=\"1.5\" stroke-dasharray=\"6 4\" stroke-opacity=\"0.8\"/><line x1=\"80.0\" y1=\"-8.0\" x2=\"140.0\" y2=\"-8.0\" stroke=\"#fbbf24\" stroke-width=\"2.5\" stroke-linecap=\"round\"/><polygon points=\"140.0,-8.0 131.9,-4.1 131.9,-11.9\" fill=\"#fbbf24\"/><text x=\"150\" y=\"-4\" font-size=\"13\" fill=\"#fbbf24\" text-anchor=\"start\" font-weight=\"700\">the top layers slip</text><text x=\"180\" y=\"162\" font-size=\"13\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">fig 1-5 b: on hammering</text></svg>","max_width":360},"visible":{"eq":1,"$state":"/h"},"children":[]},"sl":{"type":"Slider","props":{"max":1,"min":0,"step":1,"label":"Hammer (0 = no, 1 = hit)","value":{"$bindState":"/h"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","d0","d1","c1"]}}},"title":"Hammer the pure metal"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -22 360 222\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><circle cx=\"52\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"84\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"116\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"148\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"180\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"212\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><circle cx=\"244\" cy=\"30\" r=\"16\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" 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by the small atoms</text><text x=\"180\" y=\"162\" font-size=\"13\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">steel, hammered</text></svg>","max_width":360},"visible":[{"eq":1,"$state":"/c"},{"eq":1,"$state":"/h"}],"children":[]},"t":{"type":"Text","props":{"content":"Choose with or without carbon, then hammer. Compare what the hammer does to each metal."},"children":[]},"s1":{"type":"Slider","props":{"max":1,"min":0,"step":1,"label":"Carbon atoms added (0 = no, 1 = yes)","value":{"$bindState":"/c"}},"children":[]},"s2":{"type":"Slider","props":{"max":1,"min":0,"step":1,"label":"Hammer (0 = no, 1 = hit)","value":{"$bindState":"/h"}},"children":[]},"tb":{"type":"Text","props":{"content":"The layers slip: pure iron is soft."},"visible":[{"eq":0,"$state":"/c"},{"eq":1,"$state":"/h"}],"children":[]},"te":{"type":"Text","props":{"content":"The layers are blocked: steel is harder than pure iron."},"visible":[{"eq":1,"$state":"/c"},{"eq":1,"$state":"/h"}],"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","s1","s2","a","b","c","e","tb","te"]}}},"title":"Pure iron or steel?"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["malleability","ductility","melting point","electric conductivity","magnetic properties"]},"children":[]},"t":{"type":"Text","props":{"content":"The small atoms increase the hardness. They also change other physical properties of the metal:"},"children":[]},"ex":{"type":"Text","props":{"content":"Book example: the alloy of iron and carbon, steel."},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a"},{"to":"c","from":"b"}],"nodes":[{"id":"a","label":"small atoms enter the spaces of the lattice"},{"id":"b","label":"hardness increases"},{"id":"c","label":"other physical properties change"}],"layout":"horizontal","caption":"Interstitial alloy: the physical properties of the metal change (book p.19)"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","fd","b","ex"]}}},"title":"More than hardness"},{"id":"s7","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Intermetallic alloy","definition":"An alloy whose elements combine chemically into a compound. You will study it soon."},"children":[]},"t":{"type":"Text","props":{"content":"Iron and carbon can also combine chemically into cementite, $\\ce{Fe3C}$. That makes it a different type."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Fe and C","C atoms sit in the spaces","combine chemically"],["Formula","none fixed","$\\ce{Fe3C}$"],["Type","interstitial","intermetallic"]],"headers":["","Steel","Cementite"],"highlight":[{"col":1,"row":2},{"col":2,"row":2}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","tb","k"]}}},"title":"Same elements, another type"},{"id":"s8","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"M gets harder: Z atoms block the layers from slipping","correct":true},{"id":"b","text":"M gets softer: Z atoms help the layers roll","correct":false},{"id":"c","text":"Z atoms take the places of some M atoms","correct":false},{"id":"d","text":"Nothing changes: the rows are the same","correct":false}],"question":"Metal M is soft. A few atoms of element Z, much smaller than M atoms, are put into the spaces of its lattice. What happens?"},"children":[]},"fb":{"type":"FillBlank","props":{"text":"Steel is harder than pure iron because the small carbon atoms prevent the ___ of the metal layers.","answers":[["movement","slipping","slip","sliding","motion"]],"mistakes":[{"id":"m1","blank":0,"answer":"bonding"},{"id":"m2","blank":0,"answer":"melting"}]},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"In steel, some iron atoms are replaced by carbon atoms."},"children":[]},"tf2":{"type":"TrueFalse","props":{"answer":false,"statement":"Cementite, $\\ce{Fe3C}$, is an interstitial alloy, like steel."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf","tf2","fb"]}}},"title":"Check yourself"},{"id":"s9","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Pure metal: atoms in compact close rows. On hammering, a layer slips over the others.","Interstitial alloy: atoms with a small atomic size enter the spaces of the lattice.","They block the layers: the metal gets harder, and other physical properties change.","Steel (Fe + C) is interstitial. Cementite, $\\ce{Fe3C}$, is intermetallic."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam"},"children":[]},"fd":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a"},{"to":"c","from":"b"},{"to":"d","from":"c"}],"nodes":[{"id":"a","label":"pure metal: a layer slips on hammering"},{"id":"b","label":"small atoms enter the spaces"},{"id":"c","label":"the layers cannot move"},{"id":"d","label":"harder metal, e.g. steel (Fe + C)"}],"layout":"horizontal","caption":"Interstitial alloy in one chain"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fd","b","ex","self"]},"self":{"type":"Text","props":{"content":"Can you explain, with a drawing, why steel is harder than pure iron?"},"children":[]}}},"title":"Summary"}],"title":"Interstitial alloys","minutes":9,"book_ref":"Ch.1 'Types of alloys', 1- Interstitial alloys, fig 1-5 a-c, p.19; pure iron is relatively soft, p.20","subtitle":"Small atoms in the spaces stop the layers slipping","objectives":["Describe the crystal lattice of a pure metal and how its layers slip on hammering (fig 1-5 a, b).","Explain how small atoms in the spaces of the lattice make an interstitial alloy harder (fig 1-5 c).","List the physical properties that change in an interstitial alloy.","Explain why steel is harder than pure iron, and tell steel apart from cementite."],"concept_ids":["alloy.interstitial"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good prediction. The reason is inside the crystal. Let's look."},{"id":"b","feedback":"Small atoms stuck between the iron atoms get in the way of the layers; they do not help them slide, so iron does not get softer."},{"id":"c","feedback":"Even a few atoms matter: small atoms sitting in the spaces of the lattice change how the layers move."}],"explanation":"Adding carbon makes iron harder. The small carbon atoms sit in the spaces of the iron lattice and prevent the movement of its layers, so steel is harder than pure iron, which is relatively soft."}},"s4":{"mt":{"explanation":"The statement is false. In an interstitial alloy no iron atom is replaced: the carbon atoms, with a small atomic size, enter the spaces of the iron lattice.","feedback_true":"Not in this alloy. No iron atom leaves the lattice: the small carbon atoms sit in the spaces between the iron atoms.","feedback_false":"Right. No iron atom leaves; the small carbon atoms sit in the spaces of the iron lattice."}},"s8":{"q":{"options":[{"id":"a","feedback":"Right. That is an interstitial alloy."},{"id":"b","feedback":"A small atom stuck between the rows stops a layer moving past it; it does not help the layers roll, so M does not get softer."},{"id":"c","feedback":"Z atoms are much smaller than M atoms, so they go into the spaces; they do not take the places of M atoms."},{"id":"d","feedback":"The rows are still there, but the Z atoms sit between them, so the layers cannot slip as freely as before."}],"explanation":"M gets harder. Z atoms are much smaller than M atoms, so they enter the spaces of the lattice (an interstitial alloy) and block the layers from slipping on hammering."},"fb":{"mistakes":[{"id":"m1","feedback":"The atoms stay bonded either way. The small carbon atoms change what the iron layers can do when the metal is hammered, not the bonding."},{"id":"m2","feedback":"Hammering does not melt the metal. The small carbon atoms act on the iron layers when the metal is hit."}],"explanation":"On hammering, the layers of a pure metal slip. In steel, the small carbon atoms in the spaces prevent the movement of the iron layers, so steel is harder."},"tf":{"explanation":"The statement is false. Steel is an interstitial alloy: the small carbon atoms sit in the spaces between the iron atoms, and no iron atom is replaced.","feedback_true":"No iron atom leaves the lattice: in steel, the small carbon atoms fill the spaces between the iron atoms.","feedback_false":"Right. The small carbon atoms sit in the spaces."},"tf2":{"explanation":"The statement is false. In cementite, $\\ce{Fe3C}$, iron and carbon combine chemically into a compound, so it is an intermetallic alloy; steel is the interstitial one.","feedback_true":"Both contain Fe and C, but in cementite they combine chemically into a compound, so it is intermetallic, not interstitial.","feedback_false":"Right. In cementite, iron and carbon combine chemically."}},"s9":{"ex":{"body":"Give a reason: steel is harder than pure iron. Carbon atoms, with a small atomic size, enter the spaces of the iron lattice. They prevent the movement of its layers."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"توقّع حلو. السبب جوه الـ crystal. يلا نشوف."},{"id":"b","feedback":"الذرات الصغيرة المحشورة بين ذرات الـ iron بتقف في طريق الطبقات، مش بتساعدها تنزلق، فالـ iron مش بيبقى أطرى."},{"id":"c","feedback":"حتى شوية ذرات قليلين بيفرقوا: الذرات الصغيرة لما تقعد في فراغات الـ lattice بتغيّر حركة الطبقات."}],"explanation":"الـ carbon بيخلّي الـ iron أجمد. ذرات الـ carbon الصغيرة بتقعد في فراغات الـ lattice بتاع الـ iron وبتمنع حركة طبقاته، فالـ steel بيبقى أجمد من الـ pure iron اللي هو relatively soft."}},"s4":{"mt":{"explanation":"الجملة دي false. في الـ interstitial alloy مفيش ذرة iron بتتشال: ذرات الـ carbon، وحجمها الذري صغير، بتدخل في فراغات الـ lattice بتاع الـ iron.","feedback_true":"لأ، مش في الـ alloy ده. مفيش ولا ذرة iron بتسيب الـ lattice: ذرات الـ carbon الصغيرة بتقعد في الفراغات اللي بين ذرات الـ iron.","feedback_false":"صح. مفيش ذرة iron بتمشي؛ ذرات الـ carbon الصغيرة بتقعد في فراغات الـ lattice بتاع الـ iron."}},"s8":{"q":{"options":[{"id":"a","feedback":"صح. ده interstitial alloy."},{"id":"b","feedback":"الذرة الصغيرة المحشورة بين الصفوف بتوقف الطبقة اللي بتعدّي جنبها، مش بتساعد الطبقات تتدحرج، فالـ M مش بيبقى أطرى."},{"id":"c","feedback":"ذرات الـ Z أصغر بكتير من ذرات الـ M، فبتدخل في الفراغات؛ مش بتاخد أماكن ذرات الـ M."},{"id":"d","feedback":"الصفوف لسه موجودة، لكن ذرات الـ Z قاعدة بينها، فالطبقات مش هتقدر تنزلق براحتها زي الأول."}],"explanation":"الـ M بيبقى أجمد. ذرات الـ Z أصغر بكتير من ذرات الـ M، فبتدخل في فراغات الـ lattice (يعني interstitial alloy) وبتمنع الطبقات إنها تنزلق لما تتطرق."},"fb":{"mistakes":[{"id":"m1","feedback":"الذرات بتفضل مرتبطة ببعض في الحالتين، فالـ carbon مش بيمنع الترابط. اللي بيتأثر هو اللي الطبقات بتعمله لما الـ metal يتطرق."},{"id":"m2","feedback":"الطرق مش بيصهر الـ metal، فالـ carbon هنا مش بيمنع الانصهار. اللي بيتأثر هو اللي الطبقات بتعمله لما تخبطه."}],"explanation":"لما تطرق الـ pure metal، طبقاته بتنزلق. في الـ steel، ذرات الـ carbon الصغيرة اللي في الفراغات بتمنع حركة طبقات الـ iron، فالـ steel بيبقى أجمد."},"tf":{"explanation":"الجملة دي false. الـ steel هو interstitial alloy: ذرات الـ carbon الصغيرة بتقعد في الفراغات اللي بين ذرات الـ iron، ومفيش ذرة iron بتتشال.","feedback_true":"مفيش ذرة iron بتسيب الـ lattice: في الـ steel، ذرات الـ carbon الصغيرة بتملا الفراغات اللي بين ذرات الـ iron.","feedback_false":"صح. ذرات الـ carbon الصغيرة بتقعد في الفراغات."},"tf2":{"explanation":"الجملة دي false. في الـ cementite، $\\ce{Fe3C}$، الـ iron والـ carbon بيتحدوا كيميائيًا ويكوّنوا compound، فهو intermetallic alloy؛ إنما الـ steel هو اللي interstitial.","feedback_true":"الاتنين فيهم Fe و C، لكن في الـ cementite بيتحدوا كيميائيًا ويكوّنوا compound، فهو intermetallic مش interstitial.","feedback_false":"صح. في الـ cementite، الـ iron والـ carbon بيتحدوا كيميائيًا."}},"s9":{"ex":{"body":"سؤال \"Give a reason\": الـ steel أجمد من الـ pure iron. السبب: ذرات الـ carbon، اللي الـ atomic size بتاعها صغير، بتدخل في فراغات الـ iron lattice وبتمنع حركة طبقاته."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":2,"lesson_no":4,"lesson_count":6,"lesson_video":{"item_id":"chem-s3-en.video-episode-alloys","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Alloys and their types","duration_s":599.729,"start_s":188.9,"end_s":289.1,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-alloy.interstitial","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Interstitial alloys","duration_s":50.67,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 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If the lattice and chemical properties also match, the alloy is substitutional."},"visible":{"eq":1,"$state":"/k"},"children":[]},"c2":{"type":"Text","props":{"size":"sm","content":"It goes into the spaces instead. That is an interstitial alloy, like carbon in steel."},"visible":{"eq":2,"$state":"/k"},"children":[]},"c3":{"type":"Text","props":{"size":"sm","content":"It cannot simply take a host atom's place. 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bigger)","value":{"$bindState":"/k"}},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","sl","d1","c1","d2","c2","d3","c3"]}}},"title":"The fit test"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Recall: from Cr to Cu, the atomic radius is nearly constant."},"children":[]},"ch":{"type":"Chart","props":{"kind":"bar","series":[{"name":"Atomic radius","points":[{"x":"Cr","y":1.17},{"x":"Mn","y":1.17},{"x":"Fe","y":1.16},{"x":"Co","y":1.16},{"x":"Ni","y":1.15},{"x":"Cu","y":1.17}]}],"caption":"Book table, p.12 (for illustration)","x_label":"Element","y_label":"Atomic radius"},"children":[]},"t2":{"type":"Text","props":{"content":"The book says this explains their use in making alloys. An Fe atom's place fits a Cr or Ni atom."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","ch","t2"]}}},"title":"Why Fe, Cr and Ni swap easily"},{"id":"s6","kind":"interact","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Use the size of the added atom to decide."},"children":[]},"cl":{"type":"Classify","props":{"items":[{"id":"i1","text":"Ferrochrome (Fe-Cr), in stainless steel"},{"id":"i2","text":"Copper-gold alloy"},{"id":"i3","text":"Ferronickel (Fe-Ni)"},{"id":"i4","text":"Steel (Fe + C)"}],"answer":{"int":["i4"],"sub":["i1","i2","i3"]},"prompt":"Which type is each alloy?","categories":[{"id":"sub","label":"Substitutional"},{"id":"int","label":"Interstitial"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","cl"]}}},"title":"Sort the book's examples"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Substitutional","correct":true},{"id":"b","text":"Interstitial","correct":false},{"id":"c","text":"None: two metals cannot mix","correct":false}],"question":"Copper (radius 1.17) and nickel (1.15) have the same crystal lattice and similar chemical properties. Which type of alloy do they form?"},"children":[]},"q2":{"type":"MCQ","props":{"options":[{"id":"a","text":"Both elements are metals","correct":true},{"id":"b","text":"The same atomic radius","correct":false},{"id":"c","text":"The same crystal lattice","correct":false},{"id":"d","text":"The same chemical properties","correct":false}],"question":"Which of these is NOT one of the book's conditions for a substitutional alloy?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"In stainless steel, chromium atoms sit in the spaces between iron atoms."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","q2","tf"]}}},"title":"Check yourself"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Substitutional alloy: atoms of another metal replace some atoms of the pure metal.","Conditions: the same atomic radius, crystal lattice and chemical properties.","Book examples: ferrochrome (in stainless steel), copper-gold, ferronickel.","From Cr to Cu the atomic radius is nearly constant, so these metals form such alloys."]},"children":[]},"ex":{"type":"Callout","props":{"variant":"exam"},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Ferrochrome (in stainless steel)","Fe, Cr","substitutional"],["Copper-gold alloy","Cu, Au","substitutional"],["Ferronickel","Fe, Ni","substitutional"],["Steel","Fe, C","interstitial"]],"caption":"The book's examples (p.19-20)","headers":["Alloy","Elements","Type"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tb","ex","self"]},"self":{"type":"Text","props":{"content":"Can you explain why Cr atoms take iron's places, while C atoms go into the spaces?"},"children":[]}}},"title":"Summary"}],"title":"Substitutional alloys","minutes":8,"book_ref":"Ch.1 'Types of alloys', 2- Substitutional alloys, p.20; atomic radius table, p.12-13; Evaluation Q1.8, p.25","subtitle":"Atoms of the same size take each other's places","objectives":["Describe a substitutional alloy: atoms of another metal replace some atoms of the pure metal.","State the three conditions: the same atomic radius, crystal lattice and chemical properties.","Explain why metals such as Fe, Cr and Ni form substitutional alloys easily.","Classify the book's examples: ferrochrome, copper-gold, ferronickel."],"concept_ids":["alloy.substitutional"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Those spaces fit much smaller atoms, like carbon. A Cr atom (1.17) is about the size of an Fe atom (1.16), so it does not fit there."},{"id":"b","feedback":"Good. An atom of the same size can take an iron atom's place."},{"id":"c","feedback":"Atoms of two metals can mix: many alloys are two metals or more. With such close radii, the Cr atoms find a place in the iron lattice."}],"explanation":"The chromium atoms sit in the places of some iron atoms. A Cr atom (1.17) is about the same size as an Fe atom (1.16), so it can take an iron atom's place in the lattice instead of fitting into the small spaces."}},"s3":{"mt":{"explanation":"The statement is false. A substitutional alloy needs the other metal to have the same atomic radius, crystal lattice and chemical properties as the pure metal; being metals is not enough.","feedback_true":"Not so. Being metals is not enough: the other metal needs the same atomic radius, crystal lattice and chemical properties as the pure metal.","feedback_false":"Right. All three conditions are needed, not just being metals."}},"s6":{"cl":{"items":[{"id":"i1","feedback":"Fe and Cr atoms are close in size, so a Cr atom is too big for the small spaces between Fe atoms."},{"id":"i2","feedback":"Copper and gold are two metals with similar size and properties, so gold atoms do not squeeze into the small spaces between copper atoms."},{"id":"i3","feedback":"Fe 1.16, Ni 1.15: the atoms are almost the same size, and same-size metal atoms take each other's places."},{"id":"i4","feedback":"A carbon atom is smaller than an iron atom, and small atoms fit into the spaces between the metal atoms."}],"explanation":"Same-size metal atoms take each other's places. Small atoms go into the spaces."}},"s7":{"q":{"options":[{"id":"a","feedback":"Right. All three conditions hold, so Ni atoms can take Cu atoms' places."},{"id":"b","feedback":"Interstitial needs much smaller atoms in the spaces. Cu (1.17) and Ni (1.15) are nearly the same size, so neither fits in the spaces of the other."},{"id":"c","feedback":"Cu (1.17) and Ni (1.15) atoms are nearly the same size, and many alloys are two metals or more, so these two metals can mix."}],"explanation":"They form a substitutional alloy. Cu (1.17) and Ni (1.15) are nearly the same size, with the same crystal lattice and similar chemical properties, so Ni atoms can take the places of some Cu atoms."},"q2":{"options":[{"id":"a","feedback":"Right. Being metals is not enough: radius, lattice and chemical properties must all match."},{"id":"b","feedback":"The same atomic radius is one of the book's three conditions, so it is not the answer."},{"id":"c","feedback":"The same crystal lattice is one of the book's three conditions, so it is not the answer."},{"id":"d","feedback":"The same chemical properties are one of the book's three conditions, so they are not the answer."}],"explanation":"\"Both elements are metals\" is not one of the book's conditions. The three conditions are the same atomic radius, the same crystal lattice and the same chemical properties."},"tf":{"explanation":"The statement is false. Cr (1.17) and Fe (1.16) atoms are nearly the same size, so in stainless steel the Cr atoms replace some Fe atoms (a substitutional alloy) rather than sitting in the spaces.","feedback_true":"Cr (1.17) and Fe (1.16) are nearly the same size, so a Cr atom is too big for the small spaces; it replaces some Fe atoms instead.","feedback_false":"Right. Cr atoms replace some Fe atoms."}},"s8":{"ex":{"body":"Book question (p.25): \"Chromium and iron form ... alloy.\" Answer: substitutional."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الفراغات دي بتساع ذرات أصغر بكتير، زي الـ carbon. وذرة الـ Cr (1.17) تقريبًا في حجم ذرة الـ Fe (1.16)، فمش هتدخل هناك."},{"id":"b","feedback":"حلو. الذرة اللي في نفس الحجم تقدر تاخد مكان ذرة iron."},{"id":"c","feedback":"ذرات اتنين metals ممكن تتخلط: alloys كتير عبارة عن اتنين metals أو أكتر. وبـ radii قريبة كده، ذرات الـ Cr بتلاقي مكان جوه الـ lattice بتاع الـ iron."}],"explanation":"ذرات الـ chromium بتقعد في أماكن بعض ذرات الـ iron. ذرة الـ Cr (1.17) تقريبًا في نفس حجم ذرة الـ Fe (1.16)، فتقدر تاخد مكان ذرة iron في الـ lattice بدل ما تدخل في الفراغات الصغيرة."}},"s3":{"mt":{"explanation":"الجملة دي false. الـ substitutional alloy محتاج الـ metal التاني يكون ليه نفس الـ atomic radius والـ crystal lattice والـ chemical properties بتوع الـ pure metal؛ مجرد إنهم metals مش كفاية.","feedback_true":"لأ. إنهم يكونوا metals مش كفاية: الـ metal التاني لازم يكون ليه نفس الـ atomic radius والـ crystal lattice والـ chemical properties بتوع الـ pure metal.","feedback_false":"صح. لازم الشروط التلاتة مع بعض، مش مجرد إنهم metals."}},"s6":{"cl":{"items":[{"id":"i1","feedback":"الـ radii بتاعة الـ Fe والـ Cr قريبة من بعض، فذرة الـ Cr كبيرة على الفراغات الصغيرة وبتاخد مكان ذرة Fe."},{"id":"i2","feedback":"اتنين metals حجمهم وخواصهم متقاربة، فذرات الـ gold بتاخد أماكن ذرات الـ copper، مش بتتحشر في الفراغات."},{"id":"i3","feedback":"Fe 1.16، و Ni 1.15: الذرتين في نفس الحجم تقريبًا، فذرة الـ Ni بتاخد مكان ذرة Fe."},{"id":"i4","feedback":"ذرة الـ carbon أصغر من ذرة الـ iron، فبتدخل في الفراغات بين ذراته."}],"explanation":"ذرات الـ metals اللي في نفس الحجم بتاخد أماكن بعض. والذرات الصغيرة بتدخل في الفراغات."}},"s7":{"q":{"options":[{"id":"a","feedback":"صح. الشروط التلاتة متحققة، فذرات الـ Ni تقدر تاخد أماكن ذرات الـ Cu."},{"id":"b","feedback":"الـ Interstitial محتاج ذرات أصغر بكتير تدخل في الفراغات. والـ Cu (1.17) والـ Ni (1.15) تقريبًا نفس الحجم، فمحدش فيهم يدخل في فراغات التاني."},{"id":"c","feedback":"ذرات الـ Cu (1.17) والـ Ni (1.15) تقريبًا نفس الحجم، و alloys كتير عبارة عن اتنين metals أو أكتر، فالاتنين metals دول يقدروا يتخلطوا."}],"explanation":"بيكوّنوا substitutional alloy. الـ Cu (1.17) والـ Ni (1.15) تقريبًا نفس الحجم، وليهم نفس الـ crystal lattice و chemical properties متشابهة، فذرات الـ Ni تقدر تاخد أماكن بعض ذرات الـ Cu."},"q2":{"options":[{"id":"a","feedback":"صح. مجرد إنهم metals مش كفاية: الـ radius والـ lattice والـ chemical properties لازم كلهم يتطابقوا."},{"id":"b","feedback":"نفس الـ atomic radius ده شرط من شروط الكتاب التلاتة، فمش هو الإجابة."},{"id":"c","feedback":"نفس الـ crystal lattice ده شرط من شروط الكتاب التلاتة، فمش هو الإجابة."},{"id":"d","feedback":"نفس الـ chemical properties دي شرط من شروط الكتاب التلاتة، فمش هي الإجابة."}],"explanation":"«الاتنين metals» مش من شروط الكتاب. الشروط التلاتة هي نفس الـ atomic radius، ونفس الـ crystal lattice، ونفس الـ chemical properties."},"tf":{"explanation":"الجملة دي false. ذرات الـ Cr (1.17) والـ Fe (1.16) تقريبًا نفس الحجم، فالـ stainless steel ذرات الـ Cr فيه بتحل مكان بعض ذرات الـ Fe (substitutional alloy)، مش بتقعد في الفراغات.","feedback_true":"الـ Cr (1.17) والـ Fe (1.16) تقريبًا نفس الحجم، فذرة الـ Cr أكبر من إنها تدخل في الفراغات الصغيرة؛ هي بدل كده بتحل مكان بعض ذرات الـ Fe.","feedback_false":"صح. ذرات الـ Cr بتحل مكان بعض ذرات الـ Fe."}},"s8":{"ex":{"body":"سؤال الكتاب (p.25): \"Chromium and iron form ... alloy.\" الإجابة: substitutional."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":3,"lesson_no":5,"lesson_count":6,"lesson_video":{"item_id":"chem-s3-en.video-episode-alloys","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Alloys and their 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Steel is an interstitial alloy."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Same elements, same type?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Intermetallic alloy","definition":"An alloy in which the elements combine with each other chemically to form a chemical compound."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"A fixed formula means a fixed ratio of atoms. In steel, the amount of carbon can vary."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Elements","Fe + C","Fe + C"],["Formula","No fixed formula: the amount of carbon can vary","$\\ce{Fe3C}$, fixed"],["Type","Interstitial","Intermetallic: chemically combined"]],"headers":["","Steel","Cementite"],"highlight":[{"col":2,"row":1},{"col":2,"row":2}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","tb","m","t"]}}},"title":"A compound, not a mixture"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"The book adds: its chemical formula disobeys the valence law. Test $\\ce{Fe3C}$ with the swap method."},"children":[]},"t2":{"type":"Text","props":{"content":"No valency of iron gives $\\ce{Fe3C}$. The formula disobeys the valence law."},"children":[]},"t3":{"type":"Text","props":{"content":"Note: the swap pairs a metal with a non-metal. Two metals, as in $\\ce{Au2Pb}$, cannot be paired by valency at all."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["2","4","$\\ce{Fe4C2}$ → $\\ce{Fe2C}$","No"],["3","4","$\\ce{Fe4C3}$","No"]],"headers":["Iron valency","Carbon valency","Swap, then simplify","Gives Fe₃C?"],"highlight":[{"col":3,"row":0},{"col":3,"row":1}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","tb","t2","t3"]}}},"title":"Worked: test Fe₃C with valency"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It disobeys the valence law, so X and C form an intermetallic compound","correct":true},{"id":"b","text":"It obeys the valence law","correct":false},{"id":"c","text":"It is a physical mixture of X and C","correct":false}],"question":"So what does $\\ce{X3C}$ tell you?"},"children":[]},"t":{"type":"Text","props":{"content":"Metal X has valency 2 only. With carbon (valency 4), it forms $\\ce{X3C}$ in an alloy."},"children":[]},"fb":{"type":"FillBlank","props":{"text":"By the swap method, X (2) and C (4) give X___C after simplifying.","answers":[["2"]],"mistakes":[{"id":"m1","blank":0,"answer":"4"},{"id":"m2","blank":0,"answer":"3"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","fb","q"]}}},"title":"Your turn: metal X"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"In these alloys, the metals are not in the same group of the periodic table."},"children":[]},"t2":{"type":"Text","props":{"muted":true,"content":"Careful: the group alone does not decide the type. The test is a chemical compound with a fixed formula."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Duralumin","Al-Ni and Al-Cu","IIIA with VIII or IB"],["Lead-gold","$\\ce{Au2Pb}$","IB with IVA"],["Cementite","$\\ce{Fe3C}$","VIII with IVA"]],"headers":["Alloy","Elements","Groups"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","tb","t2"]}}},"title":"The book's examples"},{"id":"s6","kind":"interact","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Sort all the alloys you have met. Ask: spaces, places, or a compound?"},"children":[]},"cl":{"type":"Classify","props":{"items":[{"id":"i1","text":"Steel (Fe + C)"},{"id":"i2","text":"Cementite, $\\ce{Fe3C}$"},{"id":"i3","text":"Ferrochrome (Fe-Cr)"},{"id":"i4","text":"Copper-gold alloy"},{"id":"i5","text":"$\\ce{Au2Pb}$"},{"id":"i6","text":"Duralumin (Al-Cu)"}],"answer":{"im":["i2","i5","i6"],"int":["i1"],"sub":["i3","i4"]},"prompt":"Which type is each alloy?","categories":[{"id":"int","label":"Interstitial"},{"id":"sub","label":"Substitutional"},{"id":"im","label":"Intermetallic"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","cl"]}}},"title":"Three types, one sort"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Intermetallic","correct":true},{"id":"b","text":"Substitutional","correct":false},{"id":"c","text":"Interstitial","correct":false},{"id":"d","text":"Not an alloy: a physical mixture","correct":false}],"question":"Metals P and Q, from different groups, form an alloy with the fixed formula $\\ce{P3Q}$. Valency cannot explain this formula. What type is it?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"In duralumin, aluminum and copper are only physically mixed."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf"]}}},"title":"Check yourself"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Intermetallic alloy: the elements combine chemically to form a chemical compound.","Its formula disobeys the valence law: no valency of iron gives $\\ce{Fe3C}$.","The metals are not in the same group of the periodic table.","Book examples: duralumin (Al-Ni, Al-Cu), $\\ce{Au2Pb}$, cementite $\\ce{Fe3C}$."]},"children":[]},"r":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Show the answer"}},"children":["ra"]},"ex":{"type":"Callout","props":{"variant":"exam"},"children":[]},"ra":{"type":"Text","props":{"content":"In steel, the amount of carbon can vary: it is an interstitial alloy. In cementite, Fe and C combine chemically to form a compound with the fixed formula $\\ce{Fe3C}$: an intermetallic alloy."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","ex","self","r"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why steel and cementite are different types, though both are Fe + C?"},"children":[]}}},"title":"Summary"}],"title":"Intermetallic alloys","minutes":8,"book_ref":"Ch.1 'Types of alloys', 3) Inter-metallic alloys, p.20; Evaluation Q1.7, p.25","subtitle":"The elements combine chemically into a compound","objectives":["State that in an intermetallic alloy the elements combine chemically to form a compound.","Show that a formula such as $\\ce{Fe3C}$ disobeys the valence law.","Recall the book's examples: duralumin (Al-Ni, Al-Cu), $\\ce{Au2Pb}$ and cementite $\\ce{Fe3C}$.","Tell intermetallic alloys apart from interstitial and substitutional alloys."],"concept_ids":["alloy.intermetallic"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"The same elements can join in different ways: steel and cementite are both iron and carbon, but cementite has a fixed formula, $\\ce{Fe3C}$."},{"id":"b","feedback":"Good thinking. A fixed formula points to a compound. Let's test it."},{"id":"c","feedback":"Substitutional needs atoms of about the same radius, and a carbon atom is not the size of an iron atom."}],"explanation":"Cementite is not an interstitial alloy: in $\\ce{Fe3C}$, iron and carbon combine chemically into a compound with a fixed formula, so it is an intermetallic alloy. Steel, made of the same elements, is the interstitial one."}},"s2":{"m":{"statement":"An intermetallic alloy is a physical mixture.","correction":"Its elements are chemically combined, with a fixed formula, like $\\ce{Au2Pb}$."}},"s4":{"q":{"options":[{"id":"a","feedback":"Right. A real formula that valency cannot explain is a sign of this type."},{"id":"b","feedback":"The formula you worked out by the swap method does not match $\\ce{X3C}$."},{"id":"c","feedback":"A mixture has no fixed formula, and $\\ce{X3C}$ is a fixed formula."}],"explanation":"Valency predicts $\\ce{X2C}$, but the real formula is $\\ce{X3C}$, so it disobeys the valence law. A real formula that valency cannot explain is the sign that X and C form an intermetallic compound."},"fb":{"mistakes":[{"id":"m1","feedback":"Good swap, but the formula is not simplified yet: both numbers share a common factor."},{"id":"m2","feedback":"That is the real formula, $\\ce{X3C}$, not the one the swap method predicts from the valencies."}],"explanation":"Swapping the valencies of X (2) and C (4) gives $\\ce{X4C2}$, which simplifies to $\\ce{X2C}$."}},"s6":{"cl":{"items":[{"id":"i1","feedback":"Steel has no fixed formula: small C atoms just fill the gaps between Fe atoms."},{"id":"i2","feedback":"It has a fixed formula that valency cannot explain, so Fe and C combine chemically."},{"id":"i3","feedback":"Fe 1.16, Cr 1.17: atoms of nearly the same size take each other's places, with no fixed formula."},{"id":"i4","feedback":"Copper and gold atoms are similar in size and properties, so they take each other's places without forming a compound."},{"id":"i5","feedback":"The formula shows a fixed ratio of atoms, so the elements are not only mixed: they combine chemically."},{"id":"i6","feedback":"The book lists duralumin among the alloys whose elements combine chemically, not among those whose atoms take each other's places."}],"explanation":"Small atoms in the spaces: interstitial. Same-size atoms swap places: substitutional. Chemical combination: intermetallic."}},"s7":{"q":{"options":[{"id":"a","feedback":"Right. A fixed formula that valency cannot explain points to a chemical compound."},{"id":"b","feedback":"In a substitutional alloy, atoms take each other's places with no fixed formula, but $\\ce{P3Q}$ is a fixed formula."},{"id":"c","feedback":"Interstitial alloys have small atoms in the spaces and no fixed formula, but $\\ce{P3Q}$ is a fixed formula."},{"id":"d","feedback":"A mixture has no fixed formula, but $\\ce{P3Q}$ is a fixed formula."}],"explanation":"It is an intermetallic alloy: P and Q are metals from different groups that combine chemically into a compound with a fixed formula that disobeys the valence law."},"tf":{"explanation":"In duralumin, aluminum and copper combine chemically: the book puts duralumin among the intermetallic alloys.","feedback_true":"The book puts duralumin in the third type, where the elements combine chemically.","feedback_false":"Right. They combine chemically."}},"s8":{"ex":{"body":"Book question (p.25): \"Type of alloys in which the elements bind together chemically is ... alloy.\" Answer: intermetallic."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"نفس العناصر ممكن تترابط بأكتر من طريقة، فإن الـ steel interstitial مش معناه إن الـ $\\ce{Fe3C}$ كمان interstitial. والـ interstitial alloy مالوش formula ثابتة."},{"id":"b","feedback":"تفكير حلو. الـ formula الثابتة بتشاور على compound. يلا نختبرها."},{"id":"c","feedback":"الـ substitutional محتاج ذرات ليها نفس الـ radius تقريبًا، وذرة الـ carbon أصغر من ذرة الـ iron."}],"explanation":"الـ cementite مش interstitial alloy: في الـ $\\ce{Fe3C}$ الـ iron والـ carbon بيتحدوا كيميائيًا ويكوّنوا compound ليه formula ثابتة، فهو intermetallic alloy. أما الـ steel، اللي من نفس العناصر، فهو الـ interstitial."}},"s2":{"m":{"statement":"الـ intermetallic alloy ده physical mixture.","correction":"العناصر اللي فيه متحدة كيميائيًا، وليه formula ثابتة، زي الـ $\\ce{Au2Pb}$."}},"s4":{"q":{"options":[{"id":"a","feedback":"صح. formula حقيقية والـ valency مش قادرة تفسّرها، دي علامة على النوع ده."},{"id":"b","feedback":"الـ formula اللي طلّعتها بطريقة التبديل مش شبه الـ $\\ce{X3C}$، فالـ valency مش بتتوقعها."},{"id":"c","feedback":"الخليط مالوش formula ثابتة، والـ $\\ce{X3C}$ ليه formula ثابتة."}],"explanation":"الـ valency بتتوقع $\\ce{X2C}$، لكن الـ formula الحقيقية $\\ce{X3C}$، يعني مش ماشية على الـ valence law. والـ formula الحقيقية اللي الـ valency مش قادرة تفسّرها علامة إن X و C بيكوّنوا intermetallic compound."},"fb":{"mistakes":[{"id":"m1","feedback":"التبديل مظبوط، لكن لسه مابسّطتش: الرقمين بيتقسموا على نفس الرقم."},{"id":"m2","feedback":"ده الـ formula الحقيقي، $\\ce{X3C}$، والمطلوب هنا اللي طريقة التبديل بتتوقعه بعد التبسيط، وده رقم تاني."}],"explanation":"لما تبدّل الـ valencies بتاعة X (2) و C (4) بيطلع $\\ce{X4C2}$، ولما تبسّطه يبقى $\\ce{X2C}$."}},"s6":{"cl":{"items":[{"id":"i1","feedback":"مالوش formula ثابتة: ذرات الـ C الصغيرة يدوب بتملا الفراغات بين ذرات الـ Fe."},{"id":"i2","feedback":"ليه formula ثابتة والـ valency مش قادرة تفسّرها، يعني الـ Fe والـ C متحدين كيميائيًا."},{"id":"i3","feedback":"Fe 1.16، Cr 1.17: الذرات في نفس الحجم تقريبًا، فبتاخد أماكن بعض من غير formula ثابتة."},{"id":"i4","feedback":"حجمهم وخواصهم قريبين من بعض، فالذرات بتاخد أماكن بعض ومش بتكوّن compound."},{"id":"i5","feedback":"الـ formula فيها نسبة ذرات ثابتة، فالعناصر متحدة كيميائيًا، مش مجرد متخلطة."},{"id":"i6","feedback":"الكتاب حاطط الـ duralumin مع أمثلة النوع اللي العناصر فيه بتتحد كيميائيًا: الـ Al والـ Cu مش بياخدوا أماكن بعض وبس."}],"explanation":"ذرات صغيرة قاعدة في الفراغات: interstitial. ذرات في نفس الحجم بتاخد أماكن بعض: substitutional. اتحاد كيميائي: intermetallic."}},"s7":{"q":{"options":[{"id":"a","feedback":"صح. formula ثابتة والـ valency مش قادرة تفسّرها، يبقى بتشاور على chemical compound."},{"id":"b","feedback":"في الـ substitutional alloy الذرات بتاخد أماكن بعض ومفيش formula ثابتة، والـ $\\ce{P3Q}$ ليه formula ثابتة."},{"id":"c","feedback":"الـ interstitial alloys فيها ذرات صغيرة في الفراغات ومالهاش formula ثابتة، والـ $\\ce{P3Q}$ ليه formula ثابتة."},{"id":"d","feedback":"الخليط مالوش formula ثابتة، والـ $\\ce{P3Q}$ ليه formula ثابتة، فده مش مجرد خليط."}],"explanation":"ده intermetallic alloy: الـ P والـ Q metals من groups مختلفة، بيتحدوا كيميائيًا ويكوّنوا compound ليه formula ثابتة مش ماشية على الـ valence law."},"tf":{"explanation":"في الـ duralumin، الـ aluminum والـ copper بيتحدوا كيميائيًا: الكتاب حاطط الـ duralumin ضمن الـ intermetallic alloys.","feedback_true":"الكتاب حاطط الـ duralumin في النوع التالت، واللي العناصر فيه بتتحد كيميائيًا، مش مجرد متخلطة.","feedback_false":"صح. هما بيتحدوا كيميائيًا."}},"s8":{"ex":{"body":"سؤال الكتاب (p.25): \"Type of alloys in which the elements bind together chemically is ... alloy.\" الإجابة: intermetallic."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":4,"lesson_no":6,"lesson_count":6,"lesson_video":{"item_id":"chem-s3-en.video-episode-alloys","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Alloys and their types","duration_s":599.729,"start_s":399.2,"end_s":515.6,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-alloy.intermetallic","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Intermetallic alloys","duration_s":50.61,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"exercise":"Question 1","question":"7","relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.physical-properties","kind":"lesson","version":2,"catalog_version":3,"ord":445,"primary_concept_id":"fe.physical-properties","concepts":[{"concept_id":"fe.physical-properties","role":"primary"}],"title":"Physical properties of iron","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It is relatively soft.","correct":true},{"id":"b","text":"It is not attracted by a magnet.","correct":false},{"id":"c","text":"It melts at a low temperature.","correct":false},{"id":"d","text":"It is too hard to shape.","correct":false}],"question":"Predict: why is pure iron not used to build things?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Bridges, cars and tools are full of iron. Yet the book says pure iron has no industrial importance."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Iron everywhere, pure iron nowhere"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"The book describes pure iron like this:"},"children":[]},"t2":{"type":"Text","props":{"muted":true,"content":"Easy to shape is good for making things. Easy to dent is bad for a bridge."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Hardness","relatively soft, with low hardness"],["Malleable","yes: it can be hammered into sheets"],["Ductile","yes: it can be drawn into wires"],["Magnetic","yes: it is attracted by a magnet"]],"caption":"Physical properties of pure iron (book p.20)","headers":["Property","Pure iron"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","tab","t2"]}}},"title":"Soft, malleable, ductile, magnetic"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"v":1},"elements":{"d":{"type":"Stat","props":{"tone":"neutral","label":"Density","value":"7.87 g/cm³"},"children":[]},"m":{"type":"Stat","props":{"tone":"brand","unit":"g","label":"Mass","value":{"args":{"v":{"$state":"/v"},"expr":"7.87*v","digits":2},"$computed":"calc"}},"children":[]},"t":{"type":"Text","props":{"content":"Density = mass ÷ volume. So every 1 cm³ of pure iron has a mass of 7.87 g."},"children":[]},"v":{"type":"Slider","props":{"max":5,"min":1,"step":1,"unit":"cm³","label":"Volume of pure iron","value":{"$bindState":"/v"}},"children":[]},"mp":{"type":"Stat","props":{"tone":"neutral","label":"Melting point","value":"1538 °C"},"children":[]},"row":{"type":"Stack","props":{"gap":"md","direction":"horizontal"},"children":["mp","d"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["row","t","v","m"]}}},"title":"Melting point and density"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Columns","props":{"columns":2},"children":["d1","d2"]},"k":{"type":"KeyTerm","props":{"term_en":"Impurities","definition":"Other elements mixed with the iron, in small amounts."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Its physical properties depend upon its purity and the nature of its 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many uses."},"children":[]},"x":{"type":"Matching","props":{"pairs":[{"left":"Hammered into thin sheets","right":"malleable"},{"left":"Drawn into fine wires","right":"ductile"},{"left":"Lifted by a magnet in a scrapyard","right":"magnetic"},{"left":"Stays solid in a wood fire","right":"melts at 1538 °C"}],"prompt":"Match each everyday use to the property of iron it relies on."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["m","t","x"]}}},"title":"Many irons for many jobs"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"A block of pure iron has a mass of 78.7 g. Its density is 7.87 g/cm³. Its volume is ___ cm³.","answers":[["10","10.0","ten"]],"mistakes":[{"id":"m1","blank":0,"answer":"619.4"},{"id":"m2","blank":0,"answer":"619"},{"id":"m3","blank":0,"answer":"0.1"},{"id":"m4","blank":0,"answer":"7.87"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It contains other elements that block the slipping of its layers.","correct":true},{"id":"b","text":"It is purer than normal iron.","correct":false},{"id":"c","text":"It has a lower melting point.","correct":false},{"id":"d","text":"It has lost its magnetic properties.","correct":false}],"question":"A factory sample of iron is much harder than pure iron. 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In steel, small carbon atoms block the slipping, so steel is harder."},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rt"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Back to the hook: can you explain why bridges are built from steel, not pure iron?"},"children":[]}}},"title":"Summary"}],"title":"Physical properties of iron","minutes":6,"book_ref":"Ch.1 'Properties of Iron', p.20","subtitle":"Why pure iron is not used, and its alloys are","objectives":["List the physical properties of pure iron given in the book.","Explain why pure iron has no industrial importance and why steels and iron alloys are used."],"concept_ids":["fe.physical-properties"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Good thinking. Pure iron dents and bends too easily. Let's see why."},{"id":"b","feedback":"Scrapyards lift iron with big magnets, so magnetism is not the problem; the problem is its strength."},{"id":"c","feedback":"Iron needs a very hot furnace to melt, so a low melting point is not the problem."},{"id":"d","feedback":"A common guess: pure means hard. But pure iron can be hammered and drawn easily."}],"explanation":"Pure iron is relatively soft, with low hardness, so it is not used to build things. It is magnetic, melts at 1538 °C, and is malleable and ductile, so those are not the reason."}},"s4":{"m":{"statement":"Pure iron is very hard.","correction":"Its layers of atoms slip easily, so it is relatively soft. Small carbon atoms block the slipping: steel is harder."}},"s5":{"m":{"statement":"Pure iron is the most useful form of iron.","correction":"Adding the right elements gives steels and alloys with the properties a job needs."},"x":{"explanation":"Each use matches one property in the book's list."}},"s6":{"f":{"mistakes":[{"id":"m1","feedback":"You multiplied mass by density, but volume = mass ÷ density."},{"id":"m2","feedback":"You multiplied mass by density, but volume = mass ÷ density."},{"id":"m3","feedback":"You divided density by mass; the mass goes on top: volume = mass ÷ density."},{"id":"m4","feedback":"That is the density itself; the volume is the mass divided by it."}],"explanation":"78.7 ÷ 7.87 = 10 cm³."},"q":{"options":[{"id":"a","feedback":"Right. Its impurities, or added elements, change its properties. That is why steels are made."},{"id":"b","feedback":"Pure iron is relatively soft, so purer iron would not be harder."},{"id":"c","feedback":"Melting point does not decide hardness at room temperature."},{"id":"d","feedback":"Magnetism and hardness are different properties."}],"explanation":"The factory iron is harder because it contains other elements: the physical properties of iron depend on its purity and the nature of its impurities, and these elements block the slipping of its layers. Pure iron itself is relatively soft."},"tf":{"explanation":"The statement is false: pure iron has no industrial importance because it is relatively soft. Industry uses steels and other iron alloys, whose properties suit many uses.","feedback_true":"Pure iron is relatively soft, so it would not make a strong beam; industry uses steels and other iron alloys instead.","feedback_false":"Right. Steels and iron alloys, with chosen impurities, are used instead."}},"s7":{"e":{"body":"Give reason: pure iron has no industrial importance. Key words: it is relatively soft, with low hardness."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تفكير حلو. الـ iron النقي بيتبعج وبيتني بسهولة زيادة عن اللزوم. تعالى نشوف ليه."},{"id":"b","feedback":"محلات الخردة بترفع الـ iron بمغناطيسات كبيرة، يعني الـ iron بينجذب للمغناطيس، فدي مش المشكلة."},{"id":"c","feedback":"الـ iron محتاج فرن سخن جدًا عشان ينصهر، فالـ melting point بتاعه مش low."},{"id":"d","feedback":"تخمين بيتكرر: إن النقي يعني hard، لكن الـ iron النقي malleable و ductile وبيتشكّل بسهولة."}],"explanation":"الـ iron النقي relatively soft وصلادته قليلة، عشان كده مش بيُستخدم في البناء. هو magnetic، وبينصهر عند 1538 °C، و malleable و ductile، يعني دي مش السبب."}},"s4":{"m":{"statement":"الـ pure iron جامد جدًا.","correction":"طبقات الذرات فيه بتتزحلق على بعض بسهولة، عشان كده هو relatively soft. ذرات الـ carbon الصغيرة بتوقّف الزحلقة دي، فالـ steel بيبقى أجمد."}},"s5":{"m":{"statement":"الـ pure iron هو أكتر شكل مفيد من الـ iron.","correction":"لما بنضيف الـ elements المناسبة بنعمل steels و alloys ليها الـ properties اللي الشغلانة محتاجاها."},"x":{"explanation":"كل استخدام بيقابله property واحدة من القايمة اللي في الكتاب."}},"s6":{"f":{"mistakes":[{"id":"m1","feedback":"إنت ضربت الـ mass في الـ density، لكن الـ Volume = mass ÷ density، يعني قسمة."},{"id":"m2","feedback":"إنت ضربت الـ mass في الـ density، لكن الـ Volume = mass ÷ density، يعني قسمة."},{"id":"m3","feedback":"إنت قسمت الـ density على الـ mass، لكن الـ mass هي اللي بتيجي فوق: Volume = mass ÷ density."},{"id":"m4","feedback":"ده الـ density نفسها، والـ volume بييجي من قسمة الـ mass عليها."}],"explanation":"الحساب: 78.7 ÷ 7.87 = 10 cm³."},"q":{"options":[{"id":"a","feedback":"صح. الشوائب اللي فيه، أو العناصر اللي اتضافت له، بتغيّر خواصه. وعشان كده بيتعمل steels."},{"id":"b","feedback":"الـ iron النقي relatively soft، فالـ iron الأنقى مش هيبقى أصلب."},{"id":"c","feedback":"الـ melting point مش هي اللي بتحدد الـ hardness في درجة حرارة الأوضة."},{"id":"d","feedback":"المغناطيسية والـ hardness خاصيتين مختلفين، فالمغناطيسية مش هي اللي بتفسّر الصلابة دي."}],"explanation":"الـ iron اللي من المصنع أصلب عشان فيه عناصر تانية: الخواص الفيزيائية للـ iron بتعتمد على درجة نقاوته ونوع الشوائب اللي فيه، والعناصر دي بتمنع طبقاته إنها تتزحلق. أما الـ iron النقي نفسه فهو relatively soft."},"tf":{"explanation":"الجملة دي false: الـ iron النقي ملوش أهمية صناعية لأنه relatively soft. الصناعة بتستخدم الـ steels والـ iron alloys التانية، اللي خواصها بتناسب استخدامات كتير.","feedback_true":"الـ iron النقي relatively soft، فمينفعش يعمل كمرة متينة، والصناعة بتستخدم الـ steels والـ iron alloys بدل كده.","feedback_false":"صح. اللي بيتستخدم بداله هو الـ steels والـ iron alloys، بشوائب متختارة."}},"s7":{"e":{"body":"Give reason: الـ pure iron ملوش أهمية صناعية. الكلام المهم في الإجابة: it is relatively soft، with low hardness."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":1,"lesson_no":3,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":34.5,"end_s":108.8,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.physical-properties","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Physical properties of iron","duration_s":56.45,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.properties","section_title":"Properties of Iron","section_path":["Transition Elements","Iron","Properties of Iron"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.reactions-air-steam","kind":"lesson","version":3,"catalog_version":3,"ord":447,"primary_concept_id":"fe.reactions-air-steam","concepts":[{"concept_id":"fe.reactions-air-steam","role":"primary"}],"title":"Effect of air and water vapour","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{Fe2O3}$, like hematite","correct":false},{"id":"b","text":"$\\ce{Fe3O4}$, magnetic iron oxide","correct":true},{"id":"c","text":"None: iron only rusts in damp air","correct":false}],"question":"Predict: which oxide forms on red-hot iron in dry oxygen?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Damp air rusts iron slowly. 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In nature it is the ore magnetite."},"children":[]},"r":{"type":"Reveal","props":{"label":"Why 3 and 2?"},"children":["b"]},"t":{"type":"Text","props":{"content":"Red hot iron reacts with dry air or oxygen producing magnetic iron oxide."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","k","r"]}}},"title":"Effect of air"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Fe + H2O(v) ->[500\\,^{\\circ}C]}\\\\ \\ce{Fe3O4 + H2}\\end{gathered}","caption":"Not balanced yet: you will balance it next."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Red hot iron (500 °C) reacts with water vapour producing magnetic iron oxide and hydrogen gas."},"children":[]},"t2":{"type":"Text","props":{"content":"Water vapour gives its oxygen to iron. So water vapour is reduced to hydrogen."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","f","t2","m"]}}},"title":"Effect of water vapour"},{"id":"s4","kind":"interact","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"x":{"type":"EquationBuilder","props":{"prompt":"Balance the equation of red hot iron with water vapour.","answers":[3,4,1,4],"template":"\\ce{{?}Fe + {?}H2O ->[500\\,^{\\circ}C] {?}Fe3O4 + {?}H2}","conditions":"Red hot iron (500 °C) and water vapour"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["x","h"]}}},"title":"Balance the water vapour equation"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"In $\\ce{3Fe + 4H2O -> Fe3O4 + 4H2}$, the substance that is reduced is ___.","answers":[["water","water vapour","water vapor","steam","H2O"]],"mistakes":[{"id":"m1","blank":0,"answer":"iron"},{"id":"m2","blank":0,"answer":"Fe"},{"id":"m3","blank":0,"answer":"hydrogen"},{"id":"m4","blank":0,"answer":"Fe3O4"},{"id":"m5","blank":0,"answer":"oxygen"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Both give $\\ce{Fe3O4}$; only B also gives hydrogen gas.","correct":true},{"id":"b","text":"A gives $\\ce{Fe2O3}$; B gives $\\ce{Fe3O4}$.","correct":false},{"id":"c","text":"B gives $\\ce{Fe(OH)2}$ and hydrogen gas.","correct":false},{"id":"d","text":"Both give hydrogen gas.","correct":false}],"question":"Experiment A: red hot iron in dry air. Experiment B: red hot iron (500 °C) in water vapour. Which statement is correct?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","f"]}}},"title":"Air or water vapour?"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Red hot iron + dry air or oxygen → $\\ce{Fe3O4}$, magnetic iron oxide.","Red hot iron (500 °C) + water vapour → $\\ce{Fe3O4}$ + hydrogen gas.","Iron is oxidized in both. Water vapour is reduced to hydrogen."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"Water vapour gives its oxygen to iron, so water vapour is reduced to hydrogen. Iron gains that oxygen, so iron is oxidized."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why water vapour, not iron, is the substance reduced?"},"children":[]}}},"title":"Summary"}],"title":"Effect of air and water vapour","minutes":6,"book_ref":"Ch.1 Chemical properties 1-2 (effect of air, effect of water vapour), p.21","subtitle":"Red-hot iron gives magnetic iron oxide","objectives":["Write the equations of red-hot iron with dry air and with water vapour, with their conditions.","Name the product, magnetic iron oxide, and say which reactant is reduced by iron."],"concept_ids":["fe.reactions-air-steam"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"A natural guess: hematite is the best-known iron oxide. But iron forms more than one oxide, and hematite is not the one these conditions give."},{"id":"b","feedback":"Good thinking. It is the same compound as magnetite. Let's write the equation."},{"id":"c","feedback":"Heat speeds reactions up a lot, so red-hot iron does not stay unchanged in pure oxygen."}],"explanation":"Red-hot iron reacts with dry air or oxygen to give magnetic iron oxide, $\\ce{Fe3O4}$: $\\ce{3Fe + 2O2 -> Fe3O4}$."}},"s3":{"m":{"statement":"Iron and steam give $\\ce{Fe(OH)2}$ or $\\ce{Fe2O3}$.","correction":"The hydrogen leaves as a gas, so no hydroxide stays. The solid is again black, magnetic $\\ce{Fe3O4}$."}},"s4":{"h":{"hints":["Start like the air equation: how many Fe atoms are in $\\ce{Fe3O4}$?","How many O atoms are in $\\ce{Fe3O4}$? Each $\\ce{H2O}$ brings one.","Count the H atoms on the left. Each $\\ce{H2}$ takes two."]},"x":{"explanation":"$\\ce{Fe3O4}$ fixes 3 Fe and 4 O. Four $\\ce{H2O}$ hold 8 H atoms: four $\\ce{H2}$."}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"Iron gains oxygen here, and gaining oxygen is oxidation, not reduction."},{"id":"m2","feedback":"Iron gains oxygen here, and gaining oxygen is oxidation, not reduction."},{"id":"m3","feedback":"Hydrogen gas is a product; the substance reduced is the reactant that lost its oxygen to make it."},{"id":"m4","feedback":"That is a product; the substance reduced is the reactant that gave away its oxygen."},{"id":"m5","feedback":"Oxygen moves from one reactant to the other; the substance reduced is the reactant that loses it."}],"explanation":"Water vapour loses its oxygen to iron, so it is reduced to hydrogen."},"q":{"options":[{"id":"a","feedback":"Right. Same oxide; the water vapour also releases hydrogen."},{"id":"b","feedback":"The product of A is black and magnetic, so it is not hematite."},{"id":"c","feedback":"All the hydrogen leaves as a gas, so no H is left for a hydroxide."},{"id":"d","feedback":"Dry air reacts through its oxygen and holds no hydrogen to release."}],"explanation":"Both experiments give magnetic iron oxide, $\\ce{Fe3O4}$. In B, the water vapour also releases hydrogen gas: $\\ce{3Fe + 4H2O -> Fe3O4 + 4H2}$. In A, iron reacts with the oxygen of the air, so no hydrogen forms."}},"s6":{"e":{"body":"Write both equations with their conditions: Δ for air, 500 °C for water vapour."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تخمين منطقي: الـ hematite هو أشهر iron oxide، لكن الـ iron بيكوّن أكتر من oxide، والـ hematite مش هو اللي بيتكوّن في الظروف دي."},{"id":"b","feedback":"تفكير حلو. هو نفس الـ compound بتاع الـ magnetite. يلا نكتب المعادلة."},{"id":"c","feedback":"الحرارة بتسرّع التفاعلات جدًا، فالـ iron وهو أحمر من السخونية مش بيفضل زي ما هو في oxygen نقي."}],"explanation":"الـ iron وهو أحمر من السخونية بيتفاعل مع الهوا الجاف أو الـ oxygen ويدّي magnetic iron oxide، $\\ce{Fe3O4}$: $\\ce{3Fe + 2O2 -> Fe3O4}$."}},"s3":{"m":{"statement":"الـ iron مع الـ steam بيدّوا $\\ce{Fe(OH)2}$ أو $\\ce{Fe2O3}$.","correction":"الـ hydrogen بيطلع على هيئة gas، فمفيش hydroxide بيفضل. والمادة الصلبة اللي بتتكوّن هي برضه الـ $\\ce{Fe3O4}$ الأسود اللي بيتجذب للمغناطيس."}},"s4":{"h":{"hints":["ابدأ زي معادلة الهوا: كام ذرة Fe في الـ $\\ce{Fe3O4}$؟","كام ذرة O في الـ $\\ce{Fe3O4}$؟ كل $\\ce{H2O}$ بيجيب واحدة.","عدّ ذرات الـ H في الشمال. كل $\\ce{H2}$ بياخد اتنين."]},"x":{"explanation":"الـ $\\ce{Fe3O4}$ بيحدد 3 Fe و4 O. والأربعة $\\ce{H2O}$ فيهم 8 ذرات H: يعني أربعة $\\ce{H2}$."}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"الـ iron هنا هو اللي بياخد oxygen، وأخد الـ oxygen يبقى oxidation مش reduction."},{"id":"m2","feedback":"الـ iron هنا هو اللي بياخد oxygen، وأخد الـ oxygen يبقى oxidation مش reduction."},{"id":"m3","feedback":"الـ hydrogen gas ده ناتج، والمطلوب مادة من المتفاعلات خسرت الـ oxygen بتاعها عشان يطلع."},{"id":"m4","feedback":"ده ناتج، والمطلوب مادة من المتفاعلات هي اللي ادّت الـ oxygen بتاعها."},{"id":"m5","feedback":"الـ oxygen بينتقل من مادة متفاعلة للتانية، والمطلوب المادة اللي بتخسره، مش الـ oxygen نفسه."}],"explanation":"الـ water vapour بيدّي الـ oxygen بتاعه للـ iron، فهو اللي بيحصله reduction ويتحول لـ hydrogen."},"q":{"options":[{"id":"a","feedback":"صح. نفس الـ oxide؛ والـ water vapour كمان بيطلّع hydrogen."},{"id":"b","feedback":"ناتج تجربة A لونه أسود وبيتجذب للمغناطيس، وده مش الـ hematite."},{"id":"c","feedback":"لو الـ hydrogen كله طالع على هيئة gas، مفيش H يفضل عشان يكوّن hydroxide."},{"id":"d","feedback":"الهوا الجاف بيتفاعل عن طريق الـ oxygen اللي فيه، ومفيش منه hydrogen يطلع."}],"explanation":"التجربتين بيدّوا magnetic iron oxide، $\\ce{Fe3O4}$. في تجربة B الـ water vapour كمان بيطلّع hydrogen gas: $\\ce{3Fe + 4H2O -> Fe3O4 + 4H2}$. أما في A فالـ iron بيتفاعل مع الـ oxygen اللي في الهوا، فمفيش hydrogen بيتكوّن."}},"s6":{"e":{"body":"اكتب المعادلتين بالشروط بتاعتهم: Δ مع الهوا، و500 °C مع الـ water vapour."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":2,"lesson_no":4,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":116.3,"end_s":193.1,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.reactions-air-steam","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Effect of air and water vapour","duration_s":44.11,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.reactions-nonmetals","kind":"lesson","version":3,"catalog_version":3,"ord":449,"primary_concept_id":"fe.reactions-nonmetals","concepts":[{"concept_id":"fe.reactions-nonmetals","role":"primary"}],"title":"Iron with non-metals: chlorine and sulphur","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{FeCl2}$, iron(II) chloride","correct":false},{"id":"b","text":"$\\ce{FeCl3}$, iron(III) chloride","correct":true},{"id":"c","text":"Nothing: iron reacts only with oxygen","correct":false}],"question":"Predict: what does iron form with chlorine?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Heat iron in chlorine gas, or with sulphur powder. Both react. Do they give iron the same oxidation state?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Same metal, two partners"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{2Fe(s) + 3Cl2(g) ->[\\Delta]}\\\\ \\ce{2FeCl3(s)}\\end{gathered}"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Iron reacts with chlorine producing iron (III) chloride."},"children":[]},"t2":{"type":"Text","props":{"content":"Each Cl is −1. Three Cl give −3, so iron is +3."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","t2","m"]}}},"title":"With chlorine: iron(III) chloride"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{Fe(s) + S(s) ->[\\Delta] FeS(s)}"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Iron reacts with sulphur producing iron (II) sulphide."},"children":[]},"cc":{"type":"Columns","props":{"columns":2},"children":["k1","k2"]},"k1":{"type":"Card","props":{"tone":"warning","title":"Chlorine"},"children":["k1t"]},"k2":{"type":"Card","props":{"tone":"info","title":"Sulphur"},"children":["k2t"]},"t2":{"type":"Text","props":{"content":"In a sulphide, sulphur is −2. So iron is +2 in FeS."},"children":[]},"k1t":{"type":"Text","props":{"size":"sm","content":"Strong oxidizing agent → $\\ce{FeCl3}$, iron +3"},"children":[]},"k2t":{"type":"Text","props":{"size":"sm","content":"Weaker oxidizing agent → FeS, iron +2"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","cc","t2","m"]}}},"title":"With sulphur: iron(II) sulphide"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Formulas first: Fe + $\\ce{Cl2}$ → $\\ce{FeCl3}$. Chlorine gas comes as $\\ce{Cl2}$ molecules.","Cl: 2 on the left, 3 on the right. The lowest common multiple is 6.","6 Cl = 3 $\\ce{Cl2}$ on the left and 2 $\\ce{FeCl3}$ on the right.","Now there are 2 Fe on the right, so write 2Fe on the left."],"ordered":true},"children":[]},"f":{"type":"Formula","props":{"latex":"\\ce{2Fe + 3Cl2 ->[\\Delta] 2FeCl3}","caption":"Check: 2 Fe and 6 Cl on each side."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","f"]}}},"title":"Worked: balancing iron + chlorine"},{"id":"s5","kind":"interact","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"x":{"type":"EquationBuilder","props":{"prompt":"Aluminum also reacts with chlorine on heating, giving $\\ce{AlCl3}$. Balance the equation.","answers":[2,3,2],"template":"\\ce{{?}Al + {?}Cl2 ->[\\Delta] {?}AlCl3}"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["x","h"]}}},"title":"Your turn: a new metal"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"i1","text":"$\\ce{Fe2O3}$"},{"id":"i2","text":"$\\ce{FeSO4}$"},{"id":"i3","text":"$\\ce{FeCO3}$"},{"id":"i4","text":"$\\ce{Fe2(SO4)3}$"}],"answer":{"two":["i2","i3"],"three":["i1","i4"]},"prompt":"Find the oxidation state of iron in each compound.","categories":[{"id":"two","label":"iron(II)"},{"id":"three","label":"iron(III)"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"There is no oxygen on the left, so a sulphate cannot form.","correct":true},{"id":"b","text":"Nothing: heating iron with sulphur gives a sulphate.","correct":false},{"id":"c","text":"The product should be $\\ce{Fe2S3}$, iron(III) sulphide.","correct":false},{"id":"d","text":"Iron does not react with sulphur.","correct":false}],"question":"A student writes $\\ce{Fe + S -> FeSO4}$. What is wrong?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Iron(II) or iron(III)?"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Iron + chlorine → iron (III) chloride: $\\ce{2Fe + 3Cl2 -> 2FeCl3}$. Iron is +3.","Iron + sulphur → iron (II) sulphide: $\\ce{Fe + S -> FeS}$. Iron is +2.","Sulphur is a weaker oxidizing agent than chlorine, so iron stops at +2.","No oxygen reacts, so no sulphate forms."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"Each Cl is −1, so three Cl give −3 and iron is +3 in $\\ce{FeCl3}$. In a sulphide, sulphur is −2, so iron is +2 in FeS. Chlorine is a strong oxidizing agent; sulphur is a weaker one."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why iron is +3 in $\\ce{FeCl3}$ but +2 in FeS?"},"children":[]}}},"title":"Summary"}],"title":"Iron with non-metals: chlorine and sulphur","minutes":7,"book_ref":"Ch.1 Chemical properties 3 (with non-metals), p.21; Evaluation Q1.1, p.25","subtitle":"Iron(III) with chlorine, iron(II) with sulphur","objectives":["Write the equations of iron with chlorine and with sulphur.","State the oxidation state of iron in $\\ce{FeCl3}$ and in FeS."],"concept_ids":["fe.reactions-nonmetals"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"A common guess, but chlorine is a strong oxidizing agent, so iron does not stop at +2."},{"id":"b","feedback":"Good thinking. Let's see why iron reaches +3 here."},{"id":"c","feedback":"Oxidation is loss of electrons, with or without oxygen, and chlorine can take electrons from iron."}],"explanation":"Heated iron reacts with chlorine to give iron(III) chloride: $\\ce{2Fe + 3Cl2 -> 2FeCl3}$. Chlorine takes iron to the +3 oxidation state."}},"s2":{"m":{"statement":"Fe + $\\ce{Cl2}$ gives $\\ce{FeCl2}$.","correction":"Chlorine is a strong oxidizing agent. It takes iron to +3, the stable half-filled $3d^5$ state."}},"s3":{"m":{"statement":"Fe + S gives $\\ce{FeSO4}$ or $\\ce{Fe2S3}$.","correction":"There is no oxygen, so no sulphate. And sulphur is a weaker oxidizing agent than chlorine, so iron stops at +2: FeS."}},"s5":{"h":{"hints":["Which atom appears as a pair on the left and as a three on the right?","What is the lowest common multiple of 2 and 3?","How many $\\ce{AlCl3}$ hold that many Cl atoms? Then fix Al."]},"x":{"explanation":"Same pattern: 6 Cl atoms = 3 $\\ce{Cl2}$ = 2 $\\ce{AlCl3}$, so 2 Al."}},"s6":{"c":{"items":[{"id":"i1","feedback":"Each O is −2: three O give −6, shared equally by two Fe atoms."},{"id":"i2","feedback":"The sulphate group, $\\ce{SO4}$, is −2, and one Fe must balance it."},{"id":"i3","feedback":"The carbonate group, $\\ce{CO3}$, is −2, and one Fe balances it."},{"id":"i4","feedback":"Three $\\ce{SO4}$ groups give −6, shared equally by two Fe atoms."}],"explanation":"Total charge is zero: the iron balances the negative part."},"q":{"options":[{"id":"a","feedback":"Right. The product is iron(II) sulphide."},{"id":"b","feedback":"Heating iron with sulphur does not give a sulphate: the four O atoms of a sulphate are missing from the left side."},{"id":"c","feedback":"Sulphur is a weaker oxidizing agent than chlorine and takes iron only to +2."},{"id":"d","feedback":"Heated together, iron and sulphur do react, giving iron(II) sulphide."}],"explanation":"The left side holds Fe and S with no oxygen, so a sulphate cannot form. Heated iron and sulphur give iron(II) sulphide: $\\ce{Fe + S -> FeS}$."}},"s7":{"e":{"body":"MCQ (Q1.1): the reaction of iron and sulphur gives FeS."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تخمين ناس كتير بتقوله، لكن الـ chlorine oxidizing agent قوي وبيأكسد الـ iron لأعلى من +2."},{"id":"b","feedback":"تفكير حلو. يلا نشوف ليه الـ iron بيوصل لـ +3 هنا."},{"id":"c","feedback":"الـ oxidation هو فقد electrons، سواء فيه oxygen أو مفيش، والـ chlorine يقدر ياخد electrons من الـ iron."}],"explanation":"الـ iron لما يتسخن مع الـ chlorine بيدّي iron(III) chloride: $\\ce{2Fe + 3Cl2 -> 2FeCl3}$. الـ chlorine بيوصّل الـ iron للـ oxidation state +3."}},"s2":{"m":{"statement":"الـ Fe مع الـ $\\ce{Cl2}$ بيدّوا $\\ce{FeCl2}$.","correction":"الـ chlorine oxidizing agent قوي، فبيوصّل الـ iron لـ +3، وهي الحالة المستقرة اللي فيها الـ $3d^5$ نص ممتلئ."}},"s3":{"m":{"statement":"الـ Fe مع الـ S بيدّوا $\\ce{FeSO4}$ أو $\\ce{Fe2S3}$.","correction":"مفيش oxygen في التفاعل، يبقى مفيش sulphate. وكمان الـ sulphur oxidizing agent أضعف من الـ chlorine، فالـ iron بيقف عند +2: FeS."}},"s5":{"h":{"hints":["أنهي ذرة موجودة على هيئة زوج في الشمال وتلاتة في اليمين؟","إيه أصغر مضاعف مشترك لـ 2 و3؟","كام $\\ce{AlCl3}$ يشيلوا العدد ده من ذرات الـ Cl؟ وبعدين ظبّط الـ Al."]},"x":{"explanation":"نفس الطريقة: 6 ذرات Cl = 3 $\\ce{Cl2}$ = 2 $\\ce{AlCl3}$، يعني 2 Al."}},"s6":{"c":{"items":[{"id":"i1","feedback":"كل O بيبقى −2، فتلاتة O يدّوا −6، ومتقسمين على ذرتين Fe."},{"id":"i2","feedback":"مجموعة الـ sulphate، $\\ce{SO4}$، بتبقى −2، وذرة Fe واحدة هي اللي بتوازنها كلها."},{"id":"i3","feedback":"مجموعة الـ carbonate، $\\ce{CO3}$، بتبقى −2، وذرة Fe واحدة بتوازنها لوحدها."},{"id":"i4","feedback":"تلات مجموعات $\\ce{SO4}$ يدّوا −6، ومتقسمين على ذرتين Fe."}],"explanation":"مجموع الـ charges صفر: الـ iron هو اللي بيوازن الجزء السالب."},"q":{"options":[{"id":"a","feedback":"صح. الناتج هو iron(II) sulphide."},{"id":"b","feedback":"المعادلة دي مش موزونة: عدد ذرات الـ O في الناحيتين مش واحد."},{"id":"c","feedback":"الـ sulphur مش oxidizing agent قوي زي الـ chlorine، فمش بيوصّل الـ iron لـ +3."},{"id":"d","feedback":"لما بيتسخنوا مع بعض، الـ iron والـ sulphur بيتفاعلوا فعلًا، والـ iron بيكوّن sulphide مع non-metal زي الـ sulphur."}],"explanation":"الناحية الشمال فيها Fe و S من غير أي oxygen، فمينفعش يتكوّن sulphate. الـ iron والـ sulphur لما يتسخنوا بيدّوا iron(II) sulphide: $\\ce{Fe + S -> FeS}$."}},"s7":{"e":{"body":"في الـ MCQ (Q1.1): تفاعل الـ iron مع الـ sulphur بيدّي FeS."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":3,"lesson_no":5,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":199,"end_s":275.2,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.reactions-nonmetals","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Iron with non-metals: chlorine and sulphur","duration_s":51.07,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"exercise":"Question 1","question":"1","relation":"based_on"}]},{"id":"chem-s3-en.lesson-chem.solution-concentration","kind":"lesson","version":2,"catalog_version":3,"ord":451,"primary_concept_id":"chem.solution-concentration","concepts":[{"concept_id":"chem.solution-concentration","role":"primary"}],"title":"Concentrated and dilute solutions","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"They are two different compounds.","correct":false},{"id":"b","text":"Same acid; the concentrated one has much more acid in each volume.","correct":true},{"id":"c","text":"The dilute one has fewer H atoms in its formula.","correct":false}],"question":"Predict: what is the difference between dilute and concentrated sulphuric acid?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"In Chapter 1, two iron equations use the same acid, $\\ce{H2SO4}$. One arrow says (dil), the other says (conc.)."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Same formula, two labels"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -6 360 236\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"40\" y=\"50\" width=\"110\" height=\"130\" fill=\"#60a5fa\" fill-opacity=\"0.18\"/><path d=\"M34 20 L40 26 V180 H150 V26 L156 20\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><circle cx=\"71.4\" cy=\"119.9\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"106.3\" cy=\"67.2\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"51.2\" cy=\"152.1\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"73.3\" cy=\"85.8\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"139.6\" cy=\"111.7\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"107.1\" cy=\"155.5\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"97.1\" cy=\"141.5\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"118.2\" cy=\"125.0\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"77.1\" cy=\"63.4\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"90.0\" cy=\"162.9\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"129.1\" cy=\"70.7\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"106.4\" cy=\"93.1\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"127.1\" cy=\"169.0\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"86.9\" cy=\"76.6\" r=\"5.5\" fill=\"#facc15\"/><text x=\"95.0\" y=\"202\" font-size=\"14\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">concentrated</text><text x=\"95.0\" y=\"220\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">much solute</text><rect x=\"210\" y=\"50\" width=\"110\" height=\"130\" fill=\"#60a5fa\" fill-opacity=\"0.18\"/><path d=\"M204 20 L210 26 V180 H320 V26 L326 20\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><circle cx=\"241.2\" cy=\"71.3\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"255.6\" cy=\"77.0\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"226.0\" cy=\"104.2\" r=\"5.5\" fill=\"#facc15\"/><text x=\"265.0\" y=\"202\" font-size=\"14\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">dilute</text><text x=\"265.0\" y=\"220\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">little solute</text></svg>","caption":"Same volume of solution: many solute particles vs few","max_width":380},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Concentrated solution","definition":"A solution with a large amount of solute in a given volume."},"children":[]},"t":{"type":"Text","props":{"content":"A solution has a dissolved substance, the solute, spread through a solvent such as water."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","k","d"]}}},"title":"Concentrated solution"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"v":100},"elements":{"k":{"type":"KeyTerm","props":{"term_en":"Dilute solution","definition":"A solution with a small amount of solute in a given volume."},"children":[]},"s":{"type":"Stat","props":{"tone":"brand","label":"Solute particles in each 100 mL","value":{"args":{"v":{"$state":"/v"},"expr":"800/v","digits":1},"$computed":"calc"}},"children":[]},"t":{"type":"Text","props":{"content":"Keep the same solute. Add water to raise the volume. Watch the particles spread out."},"children":[]},"v":{"type":"Slider","props":{"max":400,"min":100,"step":100,"unit":"mL","label":"Volume of solution","value":{"$bindState":"/v"}},"children":[]},"d1":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -6 360 256\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"110\" y=\"150\" width=\"140\" height=\"50\" fill=\"#60a5fa\" fill-opacity=\"0.18\"/><path d=\"M104 10 L110 16 V200 H250 V16 L256 10\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><circle cx=\"158.9\" cy=\"164.5\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"198.1\" cy=\"162.2\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"184.3\" cy=\"171.0\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"127.0\" cy=\"175.2\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"170.9\" cy=\"184.8\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"195.3\" cy=\"188.4\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"237.2\" cy=\"161.4\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"223.0\" cy=\"168.7\" r=\"5.5\" fill=\"#facc15\"/><text x=\"180.0\" y=\"222\" font-size=\"14\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">100 mL</text><text x=\"180.0\" y=\"240\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">the same 8 solute particles</text></svg>","max_width":300},"visible":{"eq":100,"$state":"/v"},"children":[]},"d2":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -6 360 256\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"110\" y=\"105\" width=\"140\" height=\"95\" fill=\"#60a5fa\" fill-opacity=\"0.18\"/><path d=\"M104 10 L110 16 V200 H250 V16 L256 10\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><circle cx=\"158.9\" cy=\"126.3\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"198.1\" cy=\"120.4\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"184.3\" cy=\"142.4\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"127.0\" cy=\"153.1\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"128.4\" cy=\"121.8\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"170.9\" cy=\"177.0\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"195.3\" cy=\"186.1\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"237.2\" cy=\"118.5\" r=\"5.5\" fill=\"#facc15\"/><text x=\"180.0\" y=\"222\" font-size=\"14\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">200 mL</text><text x=\"180.0\" y=\"240\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">the same 8 solute particles</text></svg>","max_width":300},"visible":{"eq":200,"$state":"/v"},"children":[]},"d3":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -6 360 256\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"110\" y=\"62\" width=\"140\" height=\"138\" fill=\"#60a5fa\" fill-opacity=\"0.18\"/><path d=\"M104 10 L110 16 V200 H250 V16 L256 10\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><circle cx=\"158.9\" cy=\"89.8\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"198.1\" cy=\"80.5\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"184.3\" cy=\"115.2\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"127.0\" cy=\"131.9\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"128.4\" cy=\"82.7\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"170.9\" cy=\"169.6\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"134.9\" cy=\"98.3\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"195.3\" cy=\"183.8\" r=\"5.5\" fill=\"#facc15\"/><text x=\"180.0\" y=\"222\" font-size=\"14\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">300 mL</text><text x=\"180.0\" y=\"240\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">the same 8 solute particles</text></svg>","max_width":300},"visible":{"eq":300,"$state":"/v"},"children":[]},"d4":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -6 360 256\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"110\" y=\"20\" width=\"140\" height=\"180\" fill=\"#60a5fa\" fill-opacity=\"0.18\"/><path d=\"M104 10 L110 16 V200 H250 V16 L256 10\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><circle cx=\"158.9\" cy=\"54.1\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"198.1\" cy=\"41.6\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"184.3\" cy=\"88.5\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"127.0\" cy=\"111.2\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"128.4\" cy=\"44.5\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"170.9\" cy=\"162.3\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"134.9\" cy=\"65.7\" r=\"5.5\" fill=\"#facc15\"/><circle cx=\"195.3\" cy=\"181.6\" r=\"5.5\" fill=\"#facc15\"/><text x=\"180.0\" y=\"222\" font-size=\"14\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">400 mL</text><text x=\"180.0\" y=\"240\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">the same 8 solute particles</text></svg>","max_width":300},"visible":{"eq":400,"$state":"/v"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","t","v","d1","d2","d3","d4","s"]}}},"title":"Dilute solution: add water"},{"id":"s4","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"Adding water to a solution makes it more ___.","answers":[["dilute","diluted"]],"mistakes":[{"id":"m1","blank":0,"answer":"concentrated"},{"id":"m2","blank":0,"answer":"strong"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A","correct":true},{"id":"b","text":"B, because it holds more sugar","correct":false},{"id":"c","text":"They are equally concentrated","correct":false}],"question":"Beaker A: 5 g of sugar in 50 mL of solution. Beaker B: 10 g of sugar in 500 mL. Which is more concentrated?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Dilute sulphuric acid and concentrated sulphuric acid are different compounds."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","f","tf"]}}},"title":"Which is more concentrated?"},{"id":"s5","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Concentrated: a large amount of solute in a given volume.","Dilute: a small amount of solute in the same volume.","Adding water dilutes a solution. The solute itself does not change."]},"children":[]},"n":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"Concentration compares the solute in each volume, not the total amount. 10 g of sugar in 500 mL is $10 \\div 500 = 0.02$ g in each mL (dilute), while 5 g in 50 mL is $5 \\div 50 = 0.1$ g in each mL (concentrated)."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","n","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why 10 g of sugar can be dilute while 5 g is concentrated?"},"children":[]}}},"title":"Summary"}],"title":"Concentrated and dilute solutions","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 'with Acids', p.21: the (dil) and (conc.) labels on the iron + acid equations","subtitle":"Same acid, different amounts","objectives":["Describe a concentrated and a dilute solution by the amount of solute in a given volume.","Explain that a dilute and a concentrated acid are the same substance with different amounts of water."],"concept_ids":["chem.solution-concentration"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"The formula on both arrows is the same, so they are not two different compounds."},{"id":"b","feedback":"Good thinking. The difference is how much acid is in a given volume."},{"id":"c","feedback":"Diluting an acid does not change its formula."}],"explanation":"Dilute and concentrated sulphuric acid are the same compound, $\\ce{H2SO4}$; the concentrated one has much more acid in each volume. Diluting adds water and does not change the formula."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"Water adds volume, not solute, so each mL now holds less solute."},{"id":"m2","feedback":"This lesson compares the amount of solute in each volume, and adding water lowers it."}],"explanation":"Same solute, more volume: a more dilute solution."},"q":{"options":[{"id":"a","feedback":"Right. A has 0.1 g in each mL; B has only 0.02 g in each mL."},{"id":"b","feedback":"B holds more sugar in total, but in a much larger volume, so it has less sugar in each mL."},{"id":"c","feedback":"Dividing each mass by its volume gives two different results."}],"explanation":"Beaker A is more concentrated: it has $5 \\div 50 = 0.1$ g of sugar in each mL, while B has $10 \\div 500 = 0.02$ g in each mL. Concentration compares the solute in each volume, not the total amount."},"tf":{"explanation":"The statement is false: both are the same compound, $\\ce{H2SO4}$. What differs is the amount of acid in each volume.","feedback_true":"Both are written $\\ce{H2SO4}$: the substance is the same, and only the amount of water differs.","feedback_false":"Right. Same compound; only the amount of acid in each volume differs."}},"s5":{"n":{"body":"In Chapter 1, iron gives different products with dilute and with hot concentrated sulphuric acid."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الصيغة اللي على السهمين واحدة، فهما مش 2 compounds مختلفين."},{"id":"b","feedback":"تفكير حلو. الفرق في كمية الـ acid اللي في حجم معيّن."},{"id":"c","feedback":"التخفيف مش بيغيّر صيغة الـ acid، فعدد ذرات الـ H فيها هو هو."}],"explanation":"الـ dilute والـ concentrated sulphuric acid هما نفس الـ compound، $\\ce{H2SO4}$؛ الـ concentrated فيه acid أكتر بكتير في كل حجم. التخفيف بيزوّد مية ومش بيغيّر الـ formula."}},"s4":{"f":{"mistakes":[{"id":"m1","feedback":"المية بتزوّد الحجم، مش الـ solute، فكل mL دلوقتي فيه solute أقل."},{"id":"m2","feedback":"الدرس ده بيقارن كمية الـ solute في كل حجم، وإضافة المية بتقلّلها."}],"explanation":"نفس الـ solute في حجم أكبر: يبقى الـ solution بقى أكتر dilute."},"q":{"options":[{"id":"a","feedback":"صح. A فيه 0.1 g في كل mL، أما B فيه يدوب 0.02 g في كل mL."},{"id":"b","feedback":"B فيه سكر أكتر في المجموع، لكن في حجم أكبر بكتير، والـ concentration بتقارن السكر اللي في كل mL، مش الكمية الكلية."},{"id":"c","feedback":"لما تقسم كل كتلة على الحجم بتاعها بيطلع ناتجين مختلفين."}],"explanation":"الـ beaker A هو الأكتر concentrated: فيه $5 \\div 50 = 0.1$ g سكر في كل mL، أما B فيه $10 \\div 500 = 0.02$ g في كل mL. الـ concentration بتقارن الـ solute اللي في كل حجم، مش الكمية الكلية."},"tf":{"explanation":"الجملة دي false: الاتنين نفس الـ compound، $\\ce{H2SO4}$. اللي بيفرق هو كمية الـ acid في كل حجم.","feedback_true":"الاتنين بيتكتبوا $\\ce{H2SO4}$: المادة نفسها واحدة، واللي بيفرق هو كمية المية.","feedback_false":"صح. هو نفس الـ compound؛ الحاجة الوحيدة اللي بتفرق هي كمية الـ acid في كل حجم."}},"s5":{"n":{"body":"في الفصل الأول، الـ iron بيدّي نواتج مختلفة مع الـ dilute sulphuric acid ومع الـ hot concentrated sulphuric acid."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":1,"is_basics":true,"lesson_no":1,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-walkthrough-chem.solution-concentration","kind":"walkthrough","chapter_id":"chem-s3-en.ch1","title":"Concentrated and dilute solutions: from zero","duration_s":275.12,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-chem.solution-concentration","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Concentrated and dilute solutions","duration_s":46.15,"ord":1,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-acid.metal-acid-reaction","kind":"lesson","version":4,"catalog_version":3,"ord":453,"primary_concept_id":"acid.metal-acid-reaction","concepts":[{"concept_id":"acid.metal-acid-reaction","role":"primary"}],"title":"Metal + dilute acid","payload":{"level":"prerequisite","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Hydrogen","correct":true},{"id":"b","text":"Oxygen","correct":false},{"id":"c","text":"Chlorine","correct":false},{"id":"d","text":"Carbon dioxide","correct":false}],"question":"Predict: which gas is in the bubbles?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Drop zinc into dilute hydrochloric acid. Bubbles of gas rise, and the zinc slowly disappears."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"What is the fizz?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Callout","props":{"variant":"tip"},"children":[]},"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Zn(s) + 2HCl(aq) ->}\\\\ \\ce{ZnCl2(aq) + H2(g)}\\end{gathered}"},"children":[]},"t":{"type":"Text","props":{"content":"The metal takes the place of the hydrogen in the acid. The hydrogen comes off as a gas."},"children":[]},"t2":{"type":"Text","props":{"content":"Only metals above hydrogen in the activity series do this. Copper does not."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","t2","c"]}}},"title":"Salt + hydrogen"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Salt name: the metal + the acid's ending. $\\ce{H2SO4}$ gives sulphate: magnesium sulphate.","Formula: Mg is +2 and $\\ce{SO4}$ is −2, so $\\ce{MgSO4}$.","The gas is hydrogen, $\\ce{H2}$.","Check the atoms: 1 Mg, 2 H, 1 S, 4 O on each side."],"ordered":true},"children":[]},"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Mg(s) + H2SO4(aq) ->}\\\\ \\ce{MgSO4(aq) + H2(g)}\\end{gathered}"},"children":[]},"x":{"type":"FillBlank","props":{"text":"Now you: zinc + dilute sulphuric acid → zinc ___ + ___ gas.","answers":[["sulphate","sulfate"],["hydrogen","H2"]],"mistakes":[{"id":"m1","blank":0,"answer":"sulphide"},{"id":"m2","blank":0,"answer":"sulfide"},{"id":"m3","blank":0,"answer":"chloride"},{"id":"m4","blank":1,"answer":"oxygen"},{"id":"m5","blank":1,"answer":"water"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","f","x"]}}},"title":"Worked: magnesium + sulphuric acid"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"m":{"type":"Misconception","props":{},"children":[]},"c1":{"type":"Card","props":{"tone":"success","title":"Metal + dilute acid"},"children":["f1","t1"]},"c2":{"type":"Card","props":{"tone":"info","title":"Metal oxide + acid"},"children":["f2","t2"]},"f1":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Mg + 2HCl ->}\\\\ \\ce{MgCl2 + H2}\\end{gathered}"},"children":[]},"f2":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{MgO + 2HCl ->}\\\\ \\ce{MgCl2 + H2O}\\end{gathered}"},"children":[]},"t1":{"type":"Text","props":{"size":"sm","content":"salt + hydrogen: it fizzes"},"children":[]},"t2":{"type":"Text","props":{"size":"sm","content":"salt + water: no gas"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","m"]}}},"title":"Metal or metal oxide?"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Calcium + dilute hydrochloric acid","correct":true},{"id":"b","text":"Copper + dilute hydrochloric acid","correct":false},{"id":"c","text":"Copper (II) oxide + dilute sulphuric acid","correct":false},{"id":"d","text":"Calcium oxide + dilute hydrochloric acid","correct":false}],"question":"Which pair gives a salt and hydrogen gas?"},"children":[]},"x":{"type":"EquationBuilder","props":{"prompt":"Aluminum reacts with dilute hydrochloric acid. Balance the equation.","answers":[2,6,2,3],"template":"\\ce{{?}Al + {?}HCl -> {?}AlCl3 + {?}H2}"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["x","h","q"]}}},"title":"Your turn"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Active metal + dilute acid → salt + hydrogen gas.","Only metals above hydrogen in the activity series react this way.","Metal oxide + acid → salt + water, with no gas."]},"children":[]},"n":{"type":"Callout","props":{"variant":"info","ui_labels":{"callout.info":"Next"}},"children":[]},"r":{"type":"Reveal","props":{"ui_labels":{"reveal.label":"Show the answer"}},"children":["ra"]},"ra":{"type":"Text","props":{"content":"The metal takes the place of the hydrogen in the acid, so the hydrogen comes off as a gas. In a metal oxide, the oxygen joins the acid's hydrogen and forms water, so no gas is given off."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","n","self","r"]},"self":{"type":"Text","props":{"content":"Can you explain why a metal gives hydrogen with a dilute acid, but its oxide gives water?"},"children":[]}}},"title":"Summary"}],"title":"Metal + dilute acid","minutes":5,"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 'with Acids', p.21 (iron dissolves in dilute mineral acids)","subtitle":"Salt and hydrogen gas","objectives":["State that an active metal and a dilute acid give a salt and hydrogen gas.","Name the salt and balance the equation for a given metal and acid."],"concept_ids":["acid.metal-acid-reaction"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Right. It comes from the acid. Let's see how."},{"id":"b","feedback":"The formula HCl has no oxygen in it, so the gas cannot be oxygen."},{"id":"c","feedback":"Chlorine is a greenish gas with a sharp smell, and these bubbles are not like that."},{"id":"d","feedback":"This is the idea that every fizz with an acid is carbon dioxide. Neither zinc nor HCl contains carbon, so carbon dioxide cannot form here."}],"explanation":"The bubbles are hydrogen gas, and it comes from the acid: zinc takes the place of the hydrogen in HCl, forming the salt zinc chloride, and the hydrogen leaves as $\\ce{H2}$ gas."}},"s2":{"c":{"body":"Pattern: active metal + dilute acid → salt + hydrogen."}},"s3":{"x":{"mistakes":[{"id":"m1","feedback":"A sulphide holds S alone, but the salt keeps the whole $\\ce{SO4}$ group from $\\ce{H2SO4}$."},{"id":"m2","feedback":"A sulfide holds S alone, but the salt keeps the whole $\\ce{SO4}$ group from $\\ce{H2SO4}$."},{"id":"m3","feedback":"Chloride comes from hydrochloric acid, but this acid is sulphuric acid, and the salt's ending comes from the acid used."},{"id":"m4","feedback":"The oxygen of $\\ce{H2SO4}$ stays in the salt with the sulphur; it is not the gas that leaves when the metal takes its place."},{"id":"m5","feedback":"This is the idea that a metal and a dilute acid give a salt and water. Water forms when an oxide or a base meets an acid. Here a metal reacted, and what fizzed in the hook was a gas."}],"explanation":"Zinc + dilute sulphuric acid → zinc sulphate + hydrogen gas. The salt's ending comes from the acid ($\\ce{H2SO4}$ gives sulphate), and the hydrogen of the acid leaves as $\\ce{H2}$ gas when zinc takes its place."}},"s4":{"m":{"statement":"A metal and a dilute acid give a salt and water.","correction":"The metal takes the place of hydrogen, so hydrogen leaves as a gas. Water forms when a metal oxide reacts: its oxygen joins the acid's hydrogen."}},"s5":{"h":{"hints":["Balance Cl first: how many HCl give the 3 Cl in one $\\ce{AlCl3}$?","Now count the H on the left. Each $\\ce{H2}$ takes two. Is that a whole number?","If not, double every coefficient."]},"q":{"options":[{"id":"a","feedback":"Right. Calcium is above hydrogen, so it displaces it."},{"id":"b","feedback":"This is the idea that every metal gives hydrogen with a dilute acid. Copper is below hydrogen in the activity series, so it does not displace it from the dilute acid."},{"id":"c","feedback":"This is a metal oxide, and an oxide with an acid gives a salt and water, with no gas."},{"id":"d","feedback":"Calcium oxide is a metal oxide, and an oxide with an acid gives a salt and water, with no gas."}],"explanation":"Calcium and dilute hydrochloric acid give a salt (calcium chloride) and hydrogen gas, because calcium is above hydrogen in the activity series. Copper is below hydrogen, so it does not displace it from the dilute acid, and a metal oxide with an acid gives a salt and water, with no gas."},"x":{"explanation":"2 Al need 6 Cl: 6 HCl. Those 6 H atoms leave as 3 $\\ce{H2}$."}},"s6":{"n":{"body":"Iron is above hydrogen. Next you will see which iron salt it gives with dilute acids."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"صح. وده جاي من الـ acid. يلا نشوف إزاي."},{"id":"b","feedback":"الـ formula بتاعة HCl مافيهاش oxygen أصلًا، فالفقاقيع مش ممكن تكون oxygen."},{"id":"c","feedback":"الـ Chlorine ده gas لونه مايل للأخضر وريحته نفّاذة، والفقاقيع دي مش شبه كده."},{"id":"d","feedback":"دي فكرة إن أي فوران مع acid يبقى carbon dioxide. مافيش carbon أصلًا في الـ zinc ولا في الـ HCl، فمش ممكن يطلع carbon dioxide."}],"explanation":"الفقاقيع دي hydrogen gas، وجاية من الـ acid: الـ zinc بياخد مكان الـ hydrogen في الـ HCl، فيتكوّن الـ salt اللي اسمه zinc chloride، والـ hydrogen يطلع على شكل $\\ce{H2}$ gas."}},"s2":{"c":{"body":"القاعدة: active metal + dilute acid → salt + hydrogen."}},"s3":{"x":{"mistakes":[{"id":"m1","feedback":"الـ sulphide فيه S لوحده، إنما الـ salt هنا بياخد الـ $\\ce{SO4}$ group كله من الـ $\\ce{H2SO4}$."},{"id":"m2","feedback":"الـ sulphide فيه S لوحده، إنما الـ salt هنا بياخد الـ $\\ce{SO4}$ group كله من الـ $\\ce{H2SO4}$."},{"id":"m3","feedback":"الـ chloride بييجي من الـ hydrochloric acid، وإحنا هنا استخدمنا sulphuric acid. ونهاية اسم الـ salt جاية من الـ acid."},{"id":"m4","feedback":"الـ gas اللي بيطلع هو العنصر اللي الـ metal بياخد مكانه في الـ acid، والـ zinc مش بياخد مكان الـ oxygen اللي في الـ $\\ce{H2SO4}$."},{"id":"m5","feedback":"دي فكرة إن الـ metal مع الـ dilute acid بيدّي salt و water. الـ water بيتكوّن لما oxide أو base يقابل acid. إنما هنا اللي اتفاعل metal، وده بيطلّع gas زي الفقاقيع اللي شفناها في أول الدرس."}],"explanation":"zinc + dilute sulphuric acid → zinc sulphate + hydrogen gas. نهاية اسم الـ salt جاية من الـ acid (الـ $\\ce{H2SO4}$ بيدّي sulphate)، والـ hydrogen اللي في الـ acid بيطلع $\\ce{H2}$ gas لما الـ zinc ياخد مكانه."}},"s4":{"m":{"statement":"الـ metal مع الـ dilute acid بيدّوا salt و water.","correction":"الـ metal بياخد مكان الـ hydrogen، فالـ hydrogen بيطلع على شكل gas. الـ water بيتكوّن لما اللي يتفاعل يكون metal oxide: الـ oxygen بتاعه بيتحد مع الـ hydrogen اللي في الـ acid."}},"s5":{"h":{"hints":["وازن الـ Cl الأول: كام HCl يدّوك الـ 3 Cl اللي في $\\ce{AlCl3}$ واحد؟","دلوقتي عدّ الـ H اللي على الشمال. كل $\\ce{H2}$ بياخد اتنين. الناتج رقم صحيح؟","لو لأ، ضاعف كل coefficient."]},"q":{"options":[{"id":"a","feedback":"صح. الـ Calcium فوق الـ hydrogen، فبياخد مكانه ويطلّعه."},{"id":"b","feedback":"دي فكرة إن كل الـ metals بتطلّع hydrogen مع الـ dilute acid. الـ copper تحت الـ hydrogen في الـ activity series، فمش بياخد مكانه في الـ dilute acid."},{"id":"c","feedback":"ده metal oxide، والـ oxide مع الـ acid بيدّي salt و water من غير gas."},{"id":"d","feedback":"ده oxide تاني، والـ oxide مش بيطلّع gas مع الـ acid: بيدّي salt و water."}],"explanation":"الـ calcium مع الـ dilute hydrochloric acid بيدّوا salt (calcium chloride) و hydrogen gas، عشان الـ calcium فوق الـ hydrogen في الـ activity series. الـ copper تحت الـ hydrogen فمش بياخد مكانه في الـ dilute acid، والـ metal oxide مع الـ acid بيدّي salt و water من غير gas."},"x":{"explanation":"2 Al محتاجين 6 Cl: يعني 6 HCl. وذرات الـ H الستة دول بيطلعوا على شكل 3 $\\ce{H2}$."}},"s6":{"n":{"body":"الـ iron فوق الـ hydrogen. الجاية هتشوف بيدّي iron salt إيه مع الـ dilute acids."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":2,"is_basics":true,"lesson_no":2,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":300,"end_s":366.8,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-acid.metal-acid-reaction","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Metal + dilute acid","duration_s":49.35,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":56,"page_to":56,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.reaction-dilute-acids","kind":"lesson","version":3,"catalog_version":3,"ord":455,"primary_concept_id":"fe.reaction-dilute-acids","concepts":[{"concept_id":"fe.reaction-dilute-acids","role":"primary"}],"title":"Iron with dilute acids","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{FeCl3}$ + hydrogen","correct":false},{"id":"b","text":"$\\ce{FeCl2}$ + hydrogen","correct":true},{"id":"c","text":"No reaction","correct":false}],"question":"Predict: what does iron give with dilute hydrochloric acid?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Iron + chlorine gives iron(III) chloride, $\\ce{FeCl3}$. Hydrochloric acid, HCl, also contains chlorine."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Chlorine vs hydrochloric acid"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Mineral acids","definition":"Inorganic acids, such as hydrochloric acid (HCl) and sulphuric acid ($\\ce{H2SO4}$)."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Iron dissolves in dilute mineral acids producing iron (II) salts."},"children":[]},"f1":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Fe(s) + H2SO4(aq) ->[(dil)]}\\\\ \\ce{FeSO4(aq) + H2(g)}\\end{gathered}"},"children":[]},"f2":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Fe(s) + 2HCl(aq) ->[(dil)]}\\\\ \\ce{FeCl2(aq) + H2(g)}\\end{gathered}"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f1","f2","t","k","m"]}}},"title":"Iron dissolves in dilute acids"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"The book: iron (II) salts form, not iron (III) salts, which are reduced by the produced hydrogen."},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a","label":"iron displaces H"},{"to":"c","from":"b","label":"$\\ce{H2}$: reducing agent"},{"to":"d","from":"c","label":"+3 → +2"}],"nodes":[{"id":"a","label":"Fe + dilute acid"},{"id":"b","label":"$\\ce{H2}$ gas forms"},{"id":"c","label":"iron(III) is reduced"},{"id":"d","label":"iron(II) salt"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","fl","m"]}}},"title":"Why iron(II), not iron(III)?"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Iron gives an iron(II) salt: $\\ce{Fe^{2+}}$.","Sulphuric acid gives sulphate, $\\ce{SO4^{2-}}$: so $\\ce{FeSO4}$.","The other product is hydrogen gas, $\\ce{H2}$.","Write (dil) over the arrow, and the states."],"ordered":true},"children":[]},"x":{"type":"FillBlank","props":{"text":"Now a new acid, dilute hydrobromic acid: Fe + 2HBr → ___ + $\\ce{H2}$","answers":[["FeBr2","FeBr₂","iron(II) bromide","iron (II) bromide"]],"mistakes":[{"id":"m1","blank":0,"answer":"FeBr3"},{"id":"m2","blank":0,"answer":"FeBr"},{"id":"m3","blank":0,"answer":"Fe2Br"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","x"]}}},"title":"Worked, then faded"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"i1","text":"Iron + chlorine, heated"},{"id":"i2","text":"Iron + dilute HCl"},{"id":"i3","text":"Iron + sulphur, heated"},{"id":"i4","text":"Iron + dilute $\\ce{H2SO4}$"}],"answer":{"two":["i2","i3","i4"],"three":["i1"]},"prompt":"Does iron end as iron(II) or iron(III)?","categories":[{"id":"two","label":"iron(II) product"},{"id":"three","label":"iron(III) product"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The hydrogen produced reduces iron (III) to iron (II).","correct":true},{"id":"b","text":"Iron has no +3 oxidation state.","correct":false},{"id":"c","text":"Iron (III) is unstable, so it never forms.","correct":false},{"id":"d","text":"Dilute acids contain no chlorine or sulphate.","correct":false}],"question":"Give reason: iron reacts with dilute acids to produce iron (II) salts, not iron (III) salts."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","c"]}}},"title":"Give the reason"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Iron dissolves in dilute mineral acids: iron (II) salt + hydrogen.","$\\ce{Fe + H2SO4 -> FeSO4 + H2}$ and $\\ce{Fe + 2HCl -> FeCl2 + H2}$.","Reason: the produced hydrogen reduces iron (III) to iron (II).","Contrast: chlorine gas gives $\\ce{FeCl3}$."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rt":{"type":"Text","props":{"content":"With HCl, hydrogen forms, and the produced hydrogen reduces iron (III) to iron (II): so $\\ce{FeCl2}$ forms. Chlorine gas forms no hydrogen, so iron ends as $\\ce{FeCl3}$."},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rt"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why HCl gives $\\ce{FeCl2}$, but chlorine gives $\\ce{FeCl3}$?"},"children":[]}}},"title":"Summary"}],"title":"Iron with dilute acids","minutes":7,"book_ref":"Ch.1 Chemical properties 4 (with acids), p.21; Evaluation Q1.2, p.25 and Q7.7, p.27","subtitle":"Iron(II) salts, not iron(III) salts","objectives":["Write the equations of iron with dilute sulphuric and hydrochloric acids.","Give the book's reason why iron(II) salts, not iron(III) salts, form."],"concept_ids":["fe.reaction-dilute-acids"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"A natural guess, but here hydrogen forms, which does not happen with chlorine gas, and that hydrogen changes the product."},{"id":"b","feedback":"Good thinking. Iron stays at +2 here. Let's find out why."},{"id":"c","feedback":"Iron is above hydrogen in the activity series, so it displaces hydrogen from an acid."}],"explanation":"Iron with dilute hydrochloric acid gives iron(II) chloride and hydrogen gas: $\\ce{Fe + 2HCl -> FeCl2 + H2}$. The hydrogen produced reduces iron(III) to iron(II), so $\\ce{FeCl3}$ does not form here."}},"s2":{"m":{"statement":"Iron does not react with dilute acids.","correction":"Iron is above hydrogen in the activity series, so it displaces hydrogen: the acid fizzes."}},"s3":{"m":{"statement":"Fe + $\\ce{Cl2}$ gives $\\ce{FeCl3}$, so Fe + HCl gives $\\ce{FeCl3}$.","correction":"Chlorine gas forms no hydrogen. With HCl, hydrogen forms and keeps iron at +2."}},"s4":{"x":{"mistakes":[{"id":"m1","feedback":"Hydrogen forms here too, and it reduces iron(III) to iron(II)."},{"id":"m2","feedback":"Iron is +2 here and Br is −1, so one Br cannot balance one Fe."},{"id":"m3","feedback":"Iron is +2 and Br is −1, so the subscript belongs on Br, not on Fe."}],"explanation":"An iron(II) salt again: $\\ce{FeBr2}$, with hydrogen gas."}},"s5":{"c":{"items":[{"id":"i1","feedback":"No hydrogen forms, and chlorine is a strong oxidizing agent that takes iron to its higher oxidation state."},{"id":"i2","feedback":"Hydrogen forms here, and it reduces iron(III)."},{"id":"i3","feedback":"Sulphur is −2 in the product FeS, and one Fe balances it."},{"id":"i4","feedback":"Hydrogen forms, as with HCl, and it reduces iron(III)."}],"explanation":"Of these four, only chlorine takes iron to +3. Sulphur and dilute acids leave it at +2."},"q":{"options":[{"id":"a","feedback":"Right. That is the book's reason."},{"id":"b","feedback":"Iron does reach +3: with chlorine it gives iron(III) chloride."},{"id":"c","feedback":"Iron(III) is $3d^5$, half-filled and stable, so stability is not the reason."},{"id":"d","feedback":"HCl and $\\ce{H2SO4}$ still hold Cl and $\\ce{SO4}$ when dilute."}],"explanation":"The book's reason: iron dissolves in dilute mineral acids giving iron(II) salts, because the hydrogen produced reduces iron(III) to iron(II)."}},"s6":{"e":{"body":"Give reason (Q7.7): iron gives iron (II) salts with dilute acids. Key words: reduced by the produced hydrogen."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"تخمين منطقي، لكن وجود الـ chlorine في الـ acid مش معناه نفس ناتج الـ chlorine gas: التفاعل هنا بيكوّن حاجة ما بتتكوّنش مع الـ chlorine gas."},{"id":"b","feedback":"تفكير حلو. الـ iron بيفضل عند +2 هنا. يلا نعرف ليه."},{"id":"c","feedback":"الـ iron فوق الـ hydrogen في الـ activity series، فبيطلّع الـ hydrogen من الـ acid ويقعد مكانه."}],"explanation":"الـ iron مع الـ dilute hydrochloric acid بيدّي iron(II) chloride و hydrogen gas: $\\ce{Fe + 2HCl -> FeCl2 + H2}$. الـ hydrogen اللي بيطلع بيعمل reduction للـ iron(III) ويرجّعه iron(II)، عشان كده الـ $\\ce{FeCl3}$ مش بيتكوّن هنا."}},"s2":{"m":{"statement":"الـ iron مش بيتفاعل مع الـ dilute acids.","correction":"الـ iron فوق الـ hydrogen في الـ activity series، فبيطرد الـ hydrogen: والـ acid بيفوّر وتطلع فقاقيع."}},"s3":{"m":{"statement":"Fe + $\\ce{Cl2}$ بيدّي $\\ce{FeCl3}$، يبقى Fe + HCl برضه بيدّي $\\ce{FeCl3}$.","correction":"غاز الـ chlorine مش بيكوّن hydrogen. إنما مع الـ HCl بيتكوّن hydrogen، وده اللي بيخلّي الـ iron يفضل +2."}},"s4":{"x":{"mistakes":[{"id":"m1","feedback":"هنا كمان بيتكوّن hydrogen، والـ hydrogen ده بيعمل reduction للـ iron(III)، فالـ iron مش بيفضل +3."},{"id":"m2","feedback":"الـ iron هنا +2 والـ Br −1، فـ Br واحدة مش كفاية توازن Fe واحد."},{"id":"m3","feedback":"الـ iron +2 والـ Br −1، فالرقم الصغير مكانه مع الـ Br مش مع الـ Fe."}],"explanation":"برضه iron(II) salt: $\\ce{FeBr2}$، ومعاه hydrogen gas."}},"s5":{"c":{"items":[{"id":"i1","feedback":"مفيش hydrogen بيتكوّن هنا، والـ chlorine strong oxidizing agent بيأكسد الـ iron لأعلى من +2."},{"id":"i2","feedback":"هنا بيتكوّن hydrogen gas، والـ gas ده بيعمل reduction للـ iron(III)."},{"id":"i3","feedback":"الـ sulphur −2 في الناتج FeS، وذرة Fe واحدة هي اللي بتوازنه."},{"id":"i4","feedback":"بيتكوّن hydrogen، زي ما حصل مع الـ HCl، والـ hydrogen ده بيعمل reduction للـ iron(III)."}],"explanation":"من الأربعة دول، الـ chlorine لوحده هو اللي بيوصّل الـ iron لـ +3. الـ sulphur والـ dilute acids بيسيبوه عند +2."},"q":{"options":[{"id":"a","feedback":"صح. ده سبب الكتاب."},{"id":"b","feedback":"الـ iron بيوصل لـ +3 مع الـ chlorine، فالـ oxidation state دي موجودة عنده فعلًا."},{"id":"c","feedback":"الـ iron(III) هو $3d^5$، يعني half-filled ومستقر، فالاستقرار مش هو السبب."},{"id":"d","feedback":"الـ HCl والـ $\\ce{H2SO4}$ لسه فيهم Cl و$\\ce{SO4}$ وهم dilute، فده مش السبب."}],"explanation":"سبب الكتاب: الـ iron بيدوب في الـ dilute mineral acids ويدّي iron(II) salts، عشان الـ hydrogen اللي بيطلع من التفاعل بيعمل reduction للـ iron(III) ويحوّله iron(II)."}},"s6":{"e":{"body":"Give reason (Q7.7): الـ iron بيدّي iron (II) salts مع الـ dilute acids. الكلام المهم في الإجابة: reduced by the produced hydrogen."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":4,"lesson_no":6,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":300,"end_s":435.2,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.reaction-dilute-acids","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Iron with dilute acids","duration_s":47.7,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"exercise":"Question 1","question":"2","relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"7","relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.reaction-conc-sulfuric","kind":"lesson","version":4,"catalog_version":3,"ord":457,"primary_concept_id":"fe.reaction-conc-sulfuric","concepts":[{"concept_id":"fe.reaction-conc-sulfuric","role":"primary"}],"title":"Iron with hot concentrated sulphuric acid","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Hydrogen, as with the dilute acid","correct":false},{"id":"b","text":"Sulphur dioxide, $\\ce{SO2}$","correct":true},{"id":"c","text":"Oxygen","correct":false},{"id":"d","text":"No gas","correct":false}],"question":"Predict: which gas forms now?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"With dilute $\\ce{H2SO4}$, iron gives $\\ce{FeSO4}$ and hydrogen. Now use hot, concentrated $\\ce{H2SO4}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Same acid, but hot and concentrated"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{aligned}&\\ce{3Fe + 8H2SO4 ->[\\text{conc.},\\ \\Delta]}\\\\&\\ce{FeSO4 + Fe2(SO4)3}\\\\&\\ce{{} + 4SO2 + 8H2O}\\end{aligned}"},"children":[]},"t":{"type":"Text","props":{"content":"Iron reacts with hot concentrated sulphuric acid producing iron (II) sulphate, iron (III) sulphate, sulphur dioxide and water."},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Hot concentrated $\\ce{H2SO4}$ gives $\\ce{H2}$ gas with iron, like the dilute acid."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","tf"]}}},"title":"The book's equation"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"c":{"type":"Columns","props":{"columns":2},"children":["c1","c2"]},"t":{"type":"Text","props":{"content":"3 Fe atoms react. One ends in $\\ce{FeSO4}$, two end in $\\ce{Fe2(SO4)3}$."},"children":[]},"c1":{"type":"Card","props":{"tone":"info","title":"$\\ce{FeSO4}$"},"children":["t1"]},"c2":{"type":"Card","props":{"tone":"warning","title":"$\\ce{Fe2(SO4)3}$"},"children":["t2"]},"t1":{"type":"Text","props":{"size":"sm","content":"iron (II) sulphate: iron +2"},"children":[]},"t2":{"type":"Text","props":{"size":"sm","content":"iron (III) sulphate: iron +3"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Iron with hot concentrated $\\ce{H2SO4}$ forms only iron (III) sulphate."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","t","tf"]}}},"title":"Two salts, not one"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"A long equation is easy to misremember. Count each atom on both sides."},"children":[]},"t2":{"type":"Text","props":{"muted":true,"content":"Tip: the 8 appears twice, for the acid and for the water."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Fe","3","1 + 2 = 3"],["S","8","1 + 3 + 4 = 8"],["H","16","16 (in 8 H₂O)"],["O","32","4 + 12 + 8 + 8 = 32"]],"caption":"3Fe + 8H₂SO₄ → FeSO₄ + Fe₂(SO₄)₃ + 4SO₂ + 8H₂O","headers":["Atom","Left","Right"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","tab","t2"]}}},"title":"Worked: check the balance"},{"id":"s5","kind":"interact","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"x":{"type":"EquationBuilder","props":{"prompt":"Fill in the coefficients of the book's equation.","answers":[3,8,1,1,4,8],"template":"\\ce{{?}Fe + {?}H2SO4 ->[\\text{conc.},\\ \\Delta] {?}FeSO4 + {?}Fe2(SO4)3 + {?}SO2 + {?}H2O}","conditions":"Hot concentrated sulphuric acid"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["x","h"]}}},"title":"Rebuild it"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"i1","text":"$\\ce{H2}$"},{"id":"i2","text":"$\\ce{SO2}$"},{"id":"i3","text":"$\\ce{FeSO4}$"},{"id":"i4","text":"$\\ce{Fe2(SO4)3}$"}],"answer":{"dil":["i1"],"both":["i3"],"conc":["i2","i4"]},"prompt":"Sort each product of iron with $\\ce{H2SO4}$.","categories":[{"id":"dil","label":"dilute only"},{"id":"conc","label":"hot concentrated only"},{"id":"both","label":"both"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"$\\ce{SO2}$","correct":true},{"id":"b","text":"$\\ce{H2}$","correct":false},{"id":"c","text":"$\\ce{O2}$","correct":false}],"question":"Copper does not react with dilute $\\ce{H2SO4}$, but it reacts with hot concentrated $\\ce{H2SO4}$. Which gas forms?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c","q"]}}},"title":"Dilute or hot concentrated?"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Iron + hot concentrated $\\ce{H2SO4}$ → $\\ce{FeSO4}$ + $\\ce{Fe2(SO4)3}$ + $\\ce{SO2}$ + water.","No hydrogen: the acid's sulphur is reduced, +6 → +4 in $\\ce{SO2}$.","Iron + dilute $\\ce{H2SO4}$ → $\\ce{FeSO4}$ + $\\ce{H2}$: an iron (II) salt, not an iron (III) salt."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["$\\ce{FeSO4}$","yes","yes"],["$\\ce{Fe2(SO4)3}$","no","yes"],["$\\ce{H2}$","yes","no"],["$\\ce{SO2}$","no","yes"],["water","no","yes"]],"caption":"Iron with sulphuric acid: products (book p.21)","headers":["Product","Dilute $\\ce{H2SO4}$","Hot concentrated $\\ce{H2SO4}$"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["tab","b","e","self"]},"self":{"type":"Text","props":{"content":"Can you explain why the hot concentrated acid gives no hydrogen gas?"},"children":[]}}},"title":"Summary"}],"title":"Iron with hot concentrated sulphuric acid","minutes":7,"book_ref":"Ch.1 Chemical properties 4 (with acids), p.21","subtitle":"Two salts and sulphur dioxide","objectives":["Write the balanced equation of iron with hot concentrated sulphuric acid.","Contrast its products with those of dilute sulphuric acid."],"concept_ids":["fe.reaction-conc-sulfuric"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"Same acid, but not the same gas: hot and concentrated, the acid acts as an oxidizing agent and its sulphur is reduced to $\\ce{SO2}$, not $\\ce{H2}$."},{"id":"b","feedback":"Good thinking. The acid's sulphur ends up in $\\ce{SO2}$. Let's see the whole equation."},{"id":"c","feedback":"No O2 is released here: the acid's oxygen stays bound in compounds."},{"id":"d","feedback":"Bubbles do form: hot and concentrated, the acid acts as an oxidizing agent and gives $\\ce{SO2}$ gas."}],"explanation":"Hot and concentrated, $\\ce{H2SO4}$ acts as an oxidizing agent: its sulphur is reduced from +6 to +4, so the gas formed is sulphur dioxide, $\\ce{SO2}$, not hydrogen. No oxygen gas is released."}},"s2":{"tf":{"explanation":"The products with hot concentrated $\\ce{H2SO4}$ are $\\ce{FeSO4}$, $\\ce{Fe2(SO4)3}$, $\\ce{SO2}$ and water: no hydrogen. The acid's sulphur is reduced from +6 to +4 in $\\ce{SO2}$.","feedback_true":"Not here. Hot and concentrated, the acid acts as an oxidizing agent: its sulphur is reduced from +6 to +4, so the gas is $\\ce{SO2}$, not $\\ce{H2}$.","feedback_false":"Right. The book's products are $\\ce{FeSO4}$, $\\ce{Fe2(SO4)3}$, $\\ce{SO2}$ and water: no hydrogen. The acid's sulphur is reduced from +6 to +4 in $\\ce{SO2}$."}},"s3":{"tf":{"explanation":"Both salts form: of the 3 Fe atoms, one ends in iron (II) sulphate, $\\ce{FeSO4}$, and two in iron (III) sulphate, $\\ce{Fe2(SO4)3}$.","feedback_true":"Not quite. The book's products are a mixture: iron (II) sulphate and iron (III) sulphate. Of the 3 Fe atoms, one ends in $\\ce{FeSO4}$ and two in $\\ce{Fe2(SO4)3}$. Write both.","feedback_false":"Right. Both salts form: iron (II) sulphate ($\\ce{FeSO4}$) and iron (III) sulphate ($\\ce{Fe2(SO4)3}$)."}},"s5":{"h":{"hints":["Iron first: one Fe in the iron(II) salt, two in the iron(III) salt.","Sulphur: count S in the two salts, then add the SO₂ molecules.","The acid and the water share one coefficient."]},"x":{"explanation":"3 Fe share out as 1 + 2. 8 S share out as 1 + 3 + 4. 16 H make 8 water."}},"s6":{"c":{"items":[{"id":"i1","feedback":"Hydrogen gas forms when a metal displaces it from an acid; the hot concentrated reaction gives $\\ce{SO2}$ and water instead."},{"id":"i2","feedback":"This gas comes from the acid's sulphur being reduced, and the dilute acid gives hydrogen instead."},{"id":"i3","feedback":"The iron(II) salt appears in the equation with the dilute acid and in the one with the hot concentrated acid."},{"id":"i4","feedback":"Hydrogen reduces iron(III) to iron(II), so with the dilute acid, which gives hydrogen, the iron(III) salt does not form."}],"explanation":"Dilute: iron(II) salt + hydrogen. Hot concentrated: both salts + SO₂ + water."},"q":{"options":[{"id":"a","feedback":"Right. The hot concentrated acid acts as an oxidizing agent, not just as an acid."},{"id":"b","feedback":"Copper is below hydrogen, so it cannot displace it; the hot concentrated acid oxidizes copper and is reduced to $\\ce{SO2}$."},{"id":"c","feedback":"No O2 gas forms: the acid's oxygen stays bound in compounds; its sulphur is reduced to $\\ce{SO2}$."}],"explanation":"Copper is below hydrogen, so it does not react with dilute $\\ce{H2SO4}$. The hot concentrated acid acts as an oxidizing agent: it oxidizes copper and its sulphur is reduced to $\\ce{SO2}$."}},"s7":{"e":{"body":"Write the equation with coefficients 3, 8 → 1, 1, 4, 8 and the conditions (conc., Δ)."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"نفس الـ acid، لكن مش نفس الغاز: وهو مركّز وسخن، الـ acid بيشتغل oxidizing agent والـ sulphur بتاعه بيتختزل لـ $\\ce{SO2}$، مش $\\ce{H2}$."},{"id":"b","feedback":"تفكير حلو. الـ sulphur بتاع الـ acid بيخلص في الـ $\\ce{SO2}$. يلا نشوف المعادلة كلها."},{"id":"c","feedback":"مفيش O2 بيطلع هنا: الـ oxygen بتاع الـ acid بيفضل مربوط جوه الـ compounds."},{"id":"d","feedback":"فيه فقاقيع بتطلع فعلًا: وهو مركّز وسخن، الـ acid بيشتغل oxidizing agent وبيدّي غاز $\\ce{SO2}$."}],"explanation":"وهو مركّز وسخن، الـ $\\ce{H2SO4}$ بيشتغل oxidizing agent: الـ sulphur بتاعه بيتختزل من +6 لـ +4، فالغاز اللي بيتكوّن هو sulphur dioxide، $\\ce{SO2}$، مش hydrogen. ومفيش oxygen gas بيطلع."}},"s2":{"tf":{"explanation":"نواتج الـ $\\ce{H2SO4}$ المركّز السخن هي $\\ce{FeSO4}$ و $\\ce{Fe2(SO4)3}$ و $\\ce{SO2}$ و water: مفيش hydrogen. الـ sulphur بتاع الـ acid بيتختزل من +6 لـ +4 في الـ $\\ce{SO2}$.","feedback_true":"لأ، مش هنا. الـ acid وهو مركّز وسخن بيشتغل oxidizing agent: الـ sulphur بتاعه بيتختزل من +6 لـ +4، فالغاز اللي بيطلع هو $\\ce{SO2}$ مش $\\ce{H2}$.","feedback_false":"صح. نواتج الكتاب هي $\\ce{FeSO4}$ و $\\ce{Fe2(SO4)3}$ و $\\ce{SO2}$ و water: مفيش hydrogen. الـ sulphur بتاع الـ acid بيتختزل من +6 لـ +4 في الـ $\\ce{SO2}$."}},"s3":{"tf":{"explanation":"الـ salts الاتنين بيتكوّنوا: من الـ 3 Fe، واحد بيخلص في iron (II) sulphate، $\\ce{FeSO4}$، واتنين في iron (III) sulphate، $\\ce{Fe2(SO4)3}$.","feedback_true":"لأ مش بالظبط. نواتج الكتاب خليط: iron (II) sulphate و iron (III) sulphate. من الـ 3 Fe، واحد بيخلص في $\\ce{FeSO4}$ واتنين في $\\ce{Fe2(SO4)3}$. اكتب الاتنين.","feedback_false":"صح. الـ salts الاتنين بيتكوّنوا: iron (II) sulphate ($\\ce{FeSO4}$) و iron (III) sulphate ($\\ce{Fe2(SO4)3}$)."}},"s5":{"h":{"hints":["ابدأ بالـ iron: Fe واحد في الـ iron(II) salt، واتنين في الـ iron(III) salt.","الـ sulphur: عدّ الـ S في الـ salts الاتنين، وبعدين زوّد جزيئات الـ SO₂.","الـ acid والـ water ليهم نفس المعامل."]},"x":{"explanation":"الـ 3 Fe بيتوزعوا 1 + 2. والـ 8 S بيتوزعوا 1 + 3 + 4. والـ 16 H بيعملوا 8 water."}},"s6":{"c":{"items":[{"id":"i1","feedback":"الـ hydrogen gas بيتكوّن لما metal يحل محله في acid، والـ hot concentrated acid بيدّي $\\ce{SO2}$ ومية بدل الـ hydrogen."},{"id":"i2","feedback":"الغاز ده جاي من الـ sulphur بتاع الـ acid لما يتختزل، والـ dilute acid بيدّي hydrogen مش الغاز ده."},{"id":"i3","feedback":"الـ iron(II) salt بيظهر في نواتج الـ dilute acid، وبيظهر كمان في نواتج الـ hot concentrated acid."},{"id":"i4","feedback":"الـ hydrogen اللي بيطلع مع الـ dilute acid بيختزل الـ iron(III) لـ iron(II)، فالـ salt ده مش بيفضل في نواتج الـ dilute acid."}],"explanation":"الـ dilute: iron(II) salt + hydrogen. الـ hot concentrated: الـ salts الاتنين + SO₂ + water."},"q":{"options":[{"id":"a","feedback":"صح. الـ acid المركّز السخن بيشتغل oxidizing agent، مش مجرد acid."},{"id":"b","feedback":"الـ copper تحت الـ hydrogen، فمايقدرش يحل محله؛ الـ acid المركّز السخن بيأكسد الـ copper وهو نفسه بيتختزل لـ $\\ce{SO2}$."},{"id":"c","feedback":"مفيش O2 gas بيتكوّن: الـ oxygen بتاع الـ acid بيفضل مربوط جوه الـ compounds؛ والـ sulphur بتاعه هو اللي بيتختزل لـ $\\ce{SO2}$."}],"explanation":"الـ copper تحت الـ hydrogen، فمش بيتفاعل مع الـ dilute $\\ce{H2SO4}$. إنما الـ acid المركّز السخن بيشتغل oxidizing agent: بيأكسد الـ copper والـ sulphur بتاعه بيتختزل لـ $\\ce{SO2}$."}},"s7":{"e":{"body":"اكتب المعادلة بالمعاملات 3، 8 → 1، 1، 4، 8 ومعاها الشروط (conc.، Δ)."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":5,"lesson_no":7,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":443,"end_s":525.4,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.reaction-conc-sulfuric","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Iron with hot concentrated sulphuric acid","duration_s":51.02,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.passivity","kind":"lesson","version":2,"catalog_version":3,"ord":459,"primary_concept_id":"fe.passivity","concepts":[{"concept_id":"fe.passivity","role":"primary"}],"title":"Passivity of iron","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"It dissolves quickly.","correct":false},{"id":"b","text":"It reacts at first, then stops reacting.","correct":true},{"id":"c","text":"It fizzes and gives hydrogen, like a dilute acid.","correct":false}],"question":"Predict: an iron nail goes into concentrated nitric acid. What happens?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Dilute acids dissolve iron. So a concentrated acid should dissolve it even faster. Or should it?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"The strong acid that stops"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -24 360 228\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"20\" y=\"120\" width=\"320\" height=\"70\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><text x=\"180\" y=\"154\" font-size=\"15\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">iron</text><rect x=\"20\" y=\"111\" width=\"320\" height=\"9\" fill=\"#f59e0b\" fill-opacity=\"0.85\"/><text x=\"180\" y=\"178\" font-size=\"12\" fill=\"#f59e0b\" text-anchor=\"middle\" font-weight=\"700\">thin oxide layer on top</text><circle cx=\"50\" cy=\"30\" r=\"7\" fill=\"#60a5fa\"/><line x1=\"50.0\" y1=\"42.0\" x2=\"50.0\" y2=\"94.0\" stroke=\"#60a5fa\" stroke-width=\"2\" stroke-linecap=\"round\"/><polygon points=\"50.0,94.0 47.0,87.7 53.0,87.7\" fill=\"#60a5fa\"/><path d=\"M43 98 L57 108 M57 98 L43 108\" stroke=\"#ef4444\" stroke-width=\"3\"/><circle cx=\"110\" cy=\"52\" r=\"7\" fill=\"#60a5fa\"/><line x1=\"110.0\" y1=\"64.0\" x2=\"110.0\" y2=\"94.0\" stroke=\"#60a5fa\" stroke-width=\"2\" stroke-linecap=\"round\"/><polygon points=\"110.0,94.0 107.0,87.7 113.0,87.7\" fill=\"#60a5fa\"/><path d=\"M103 98 L117 108 M117 98 L103 108\" stroke=\"#ef4444\" stroke-width=\"3\"/><circle cx=\"170\" cy=\"30\" r=\"7\" fill=\"#60a5fa\"/><line x1=\"170.0\" y1=\"42.0\" x2=\"170.0\" y2=\"94.0\" stroke=\"#60a5fa\" stroke-width=\"2\" stroke-linecap=\"round\"/><polygon points=\"170.0,94.0 167.0,87.7 173.0,87.7\" fill=\"#60a5fa\"/><path d=\"M163 98 L177 108 M177 98 L163 108\" stroke=\"#ef4444\" stroke-width=\"3\"/><circle cx=\"230\" cy=\"52\" r=\"7\" fill=\"#60a5fa\"/><line x1=\"230.0\" y1=\"64.0\" x2=\"230.0\" y2=\"94.0\" stroke=\"#60a5fa\" stroke-width=\"2\" stroke-linecap=\"round\"/><polygon points=\"230.0,94.0 227.0,87.7 233.0,87.7\" fill=\"#60a5fa\"/><path d=\"M223 98 L237 108 M237 98 L223 108\" stroke=\"#ef4444\" stroke-width=\"3\"/><circle cx=\"290\" cy=\"30\" r=\"7\" fill=\"#60a5fa\"/><line x1=\"290.0\" y1=\"42.0\" x2=\"290.0\" y2=\"94.0\" stroke=\"#60a5fa\" stroke-width=\"2\" stroke-linecap=\"round\"/><polygon points=\"290.0,94.0 287.0,87.7 293.0,87.7\" fill=\"#60a5fa\"/><path d=\"M283 98 L297 108 M297 98 L283 108\" stroke=\"#ef4444\" stroke-width=\"3\"/><text x=\"20\" y=\"-6\" font-size=\"13\" fill=\"#60a5fa\" text-anchor=\"start\" font-weight=\"700\">conc. nitric acid</text><text x=\"345\" y=\"-6\" font-size=\"13\" fill=\"#ef4444\" text-anchor=\"end\" font-weight=\"700\">no further reaction</text></svg>","max_width":380},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Passivity of iron","definition":"Caused by concentrated nitric acid: a thin layer of oxide forms, which protects the metal from further reaction."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Remember chromium: its oxide layer stops further reaction with air. Here, an oxide layer stops the acid."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","d","t","m"]}}},"title":"A thin layer of oxide"},{"id":"s3","kind":"interact","spec":{"root":"root","state":{"s":1},"elements":{"s":{"type":"Slider","props":{"max":4,"min":1,"step":1,"label":"Stage","value":{"$bindState":"/s"}},"children":[]},"t":{"type":"Text","props":{"content":"Move the slider, stage by stage."},"children":[]},"c1":{"type":"Text","props":{"content":"1. Concentrated nitric acid meets clean iron."},"visible":{"eq":1,"$state":"/s"},"children":[]},"c2":{"type":"Text","props":{"content":"2. A thin oxide layer forms on the surface."},"visible":{"eq":2,"$state":"/s"},"children":[]},"c3":{"type":"Text","props":{"content":"3. The layer protects the iron: no further reaction."},"visible":{"eq":3,"$state":"/s"},"children":[]},"c4":{"type":"Text","props":{"content":"4. Abrasion or dilute hydrochloric acid removes the layer."},"visible":{"eq":4,"$state":"/s"},"children":[]},"d1":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -24 360 228\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"20\" y=\"120\" width=\"320\" height=\"70\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><text x=\"180\" y=\"154\" font-size=\"15\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">iron</text><circle cx=\"50\" cy=\"30\" r=\"7\" fill=\"#60a5fa\"/><line x1=\"50.0\" y1=\"42.0\" x2=\"50.0\" y2=\"114.0\" stroke=\"#60a5fa\" stroke-width=\"2\" stroke-linecap=\"round\"/><polygon points=\"50.0,114.0 47.0,107.7 53.0,107.7\" fill=\"#60a5fa\"/><circle cx=\"110\" cy=\"52\" r=\"7\" fill=\"#60a5fa\"/><line x1=\"110.0\" y1=\"64.0\" x2=\"110.0\" y2=\"114.0\" stroke=\"#60a5fa\" stroke-width=\"2\" stroke-linecap=\"round\"/><polygon points=\"110.0,114.0 107.0,107.7 113.0,107.7\" fill=\"#60a5fa\"/><circle cx=\"170\" 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xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"20\" y=\"120\" width=\"320\" height=\"70\" fill=\"#94a3b8\" fill-opacity=\"0.35\" stroke=\"#94a3b8\" stroke-width=\"2\"/><text x=\"180\" y=\"154\" font-size=\"15\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">iron</text><rect x=\"20\" y=\"111\" width=\"320\" height=\"9\" fill=\"#f59e0b\" fill-opacity=\"0.85\"/><text x=\"180\" y=\"178\" font-size=\"12\" fill=\"#f59e0b\" text-anchor=\"middle\" font-weight=\"700\">thin oxide layer on top</text><circle cx=\"50\" cy=\"30\" r=\"7\" fill=\"#60a5fa\"/><circle cx=\"110\" cy=\"52\" r=\"7\" fill=\"#60a5fa\"/><circle cx=\"170\" cy=\"30\" r=\"7\" fill=\"#60a5fa\"/><circle cx=\"230\" cy=\"52\" r=\"7\" fill=\"#60a5fa\"/><circle cx=\"290\" cy=\"30\" r=\"7\" fill=\"#60a5fa\"/><text x=\"20\" y=\"-6\" font-size=\"13\" fill=\"#60a5fa\" text-anchor=\"start\" font-weight=\"700\">conc. nitric 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exposed</text></svg>","max_width":380},"visible":{"eq":4,"$state":"/s"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","s","d1","d2","d3","d4","c1","c2","c3","c4"]}}},"title":"Follow the surface"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Abrasion","definition":"Rubbing a surface hard, for example with sandpaper."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"This layer can be removed by abrasion or by using dilute hydrochloric acid."},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a","label":"abrasion or dilute HCl"},{"to":"c","from":"b"}],"nodes":[{"id":"a","label":"Passive iron: thin oxide layer"},{"id":"b","label":"Fresh iron exposed"},{"id":"c","label":"Iron reacts again"}]},"children":[]},"t2":{"type":"Text","props":{"content":"With the layer gone, fresh iron is exposed and can react again."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","k","t2","fl","m"]}}},"title":"Not permanent"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"The passive layer is removed by ___ or by dilute ___ acid.","answers":[["abrasion","rubbing","abrading","sanding","sandpaper","scraping","scrubbing"],["hydrochloric","HCl"]],"mistakes":[{"id":"m1","blank":1,"answer":"nitric"},{"id":"m2","blank":1,"answer":"sulphuric"},{"id":"m3","blank":1,"answer":"sulfuric"},{"id":"m4","blank":0,"answer":"heating"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Rubbing removed the oxide layer, so fresh iron could displace copper.","correct":true},{"id":"b","text":"Sandpaper added copper to the nail.","correct":false},{"id":"c","text":"Iron is below copper, so it needed rubbing to react.","correct":false},{"id":"d","text":"Rubbing made the iron passive.","correct":false}],"question":"A passive iron nail is put into copper (II) sulphate solution. Nothing happens. After rubbing it with sandpaper, copper coats it. Why?"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Once iron is made passive, it can never react again."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["q","tf","f"]}}},"title":"Your turn"},{"id":"s6","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Concentrated nitric acid makes iron passive: a thin layer of oxide forms.","The layer protects the metal from further reaction.","It is removed by abrasion or by dilute hydrochloric acid.","Same idea as chromium: a surface oxide layer stops further reaction."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rt":{"type":"Text","props":{"content":"Concentrated nitric acid forms a thin layer of oxide on the iron, and the layer protects the metal from further reaction. Dilute HCl removes that layer, so fresh iron stays exposed and reacts."},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rt"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why iron stops reacting with concentrated nitric acid, while dilute HCl dissolves it?"},"children":[]}}},"title":"Summary"}],"title":"Passivity of iron","minutes":6,"book_ref":"Ch.1 Chemical properties 4 (with acids), p.21; Evaluation Q7.10, p.27","subtitle":"A thin oxide layer stops the attack","objectives":["Explain why concentrated nitric acid causes the passivity of iron.","State the two ways the book gives to remove the passive layer."],"concept_ids":["fe.passivity"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"That is the usual guess, but an active metal can resist attack: air does not attack very active chromium."},{"id":"b","feedback":"Good thinking. Something forms on the surface and protects it."},{"id":"c","feedback":"Concentrated nitric acid does not behave like a dilute acid here: like chromium, iron gets a protective surface layer."}],"explanation":"The nail reacts at first, then stops: concentrated nitric acid causes passivity of iron. A thin oxide layer forms on the surface and protects the metal from further reaction."}},"s2":{"m":{"statement":"Concentrated $\\ce{HNO3}$ dissolves iron quickly.","correction":"The oxide layer it forms covers the iron and blocks further reaction."}},"s4":{"m":{"statement":"Passivity is permanent.","correction":"The layer is only on the surface: rub it off, or dissolve it in dilute HCl, and the iron reacts again."}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"Nitric acid made the layer; the book removes it with a different dilute acid."},{"id":"m2","feedback":"The book names a different dilute acid to remove the layer."},{"id":"m3","feedback":"The book names a different dilute acid to remove the layer."},{"id":"m4","feedback":"The book uses a mechanical way on the surface, not heat."}],"explanation":"Abrasion (rubbing) or dilute hydrochloric acid."},"q":{"options":[{"id":"a","feedback":"Right. Iron is above copper, but only bare iron can react."},{"id":"b","feedback":"Sandpaper only rubs; the copper came from the solution, not from the paper."},{"id":"c","feedback":"Iron is above copper in the activity series, so its position did not stop the reaction."},{"id":"d","feedback":"The nitric acid caused the passivity, not the rubbing."}],"explanation":"Rubbing with sandpaper removed the oxide layer, so fresh iron could displace copper from the copper (II) sulphate solution. Iron is above copper in the activity series, but the passive layer stopped the reaction before rubbing."},"tf":{"explanation":"The statement is false: the protective oxide layer can be removed by abrasion or by using dilute hydrochloric acid, and then the iron can react again.","feedback_true":"The layer is only on the surface, and the book gives two treatments that expose fresh iron.","feedback_false":"Right. Abrasion or dilute hydrochloric acid removes the layer."}},"s6":{"e":{"body":"Give reason (Q7.10): concentrated nitric acid causes the passivity of iron. Key words: thin layer of oxide, protects the metal from further reaction."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"ده التوقّع المعتاد، لكن النشاط لوحده مش بيحدد: الـ chromium نشط جدًا ومع كده الهوا مش بيهاجمه."},{"id":"b","feedback":"تفكير حلو. فيه حاجة بتتكوّن على السطح وبتحميه."},{"id":"c","feedback":"الـ concentrated nitric acid هنا مش بيتصرّف زي الـ dilute acid، فالمسمار مش بيفوّر ويطلّع hydrogen."}],"explanation":"المسمار بيتفاعل في الأول وبعدين بيقف: الـ concentrated nitric acid بيعمل passivity للـ iron. بتتكوّن طبقة oxide رفيعة على السطح وبتحمي الـ metal من إنه يكمّل تفاعل."}},"s2":{"m":{"statement":"الـ concentrated $\\ce{HNO3}$ بيدوّب الـ iron بسرعة.","correction":"طبقة الـ oxide اللي بيكوّنها بتغطي الـ iron وبتمنع أي تفاعل بعد كده."}},"s4":{"m":{"statement":"الـ passivity حاجة دايمة.","correction":"الطبقة دي على السطح من بره: لو شلتها بالـ abrasion (الحكّ) أو دوّبتها في dilute HCl، الـ iron يرجع يتفاعل تاني."}},"s5":{"f":{"mistakes":[{"id":"m1","feedback":"الـ nitric acid هو اللي عمل الطبقة، فمش هو اللي بيشيلها."},{"id":"m2","feedback":"الكتاب بيذكر dilute acid تاني غير الـ sulphuric عشان يشيل الطبقة."},{"id":"m3","feedback":"الكتاب بيذكر dilute acid تاني غير الـ sulphuric عشان يشيل الطبقة."},{"id":"m4","feedback":"الكتاب بيشيل الطبقة بطريقة ميكانيكية، مش بالحرارة."}],"explanation":"بالـ abrasion (الحكّ) أو بالـ dilute hydrochloric acid."},"q":{"options":[{"id":"a","feedback":"صح. الـ iron فوق الـ copper، لكن مفيش غير الـ iron المكشوف هو اللي يقدر يتفاعل."},{"id":"b","feedback":"ورق الصنفرة مجرد بيحكّ ومفيهوش copper؛ الـ copper جاي من الـ solution."},{"id":"c","feedback":"الـ iron فوق الـ copper في الـ activity series، مش تحته."},{"id":"d","feedback":"الـ nitric acid هو اللي عمل الـ passivity، والحكّ مش بيعمل passivity."}],"explanation":"الحكّ بورق الصنفرة شال طبقة الـ oxide، فالـ iron الجديد قدر يطرد الـ copper من محلول الـ copper (II) sulphate. الـ iron فوق الـ copper في الـ activity series، لكن الطبقة اللي عملت الـ passivity كانت موقّفة التفاعل قبل الحكّ."},"tf":{"explanation":"الجملة دي false: طبقة الـ oxide الحامية ممكن تتشال بالـ abrasion أو بالـ dilute hydrochloric acid، وساعتها الـ iron يقدر يتفاعل تاني.","feedback_true":"الطبقة دي على السطح تحديدًا، والكتاب بيذكر طريقتين بيشيلوها ويكشفوا الـ iron الجديد.","feedback_false":"صح. الـ abrasion أو الـ dilute hydrochloric acid بيشيلوا الطبقة."}},"s6":{"e":{"body":"Give reason (Q7.10): الـ concentrated nitric acid بيعمل passivity للـ iron. الكلام المهم في الإجابة: thin layer of oxide، و protects the metal from further reaction."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":6,"lesson_no":8,"lesson_count":8,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-reactions","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Properties of iron","duration_s":709.459,"start_s":549.1,"end_s":620.2,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.passivity","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Passivity of iron","duration_s":46.23,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"10","relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.oxide-feo","kind":"lesson","version":3,"catalog_version":3,"ord":494,"primary_concept_id":"fe.oxide-feo","concepts":[{"concept_id":"fe.oxide-feo","role":"primary"}],"title":"Iron(II) oxide FeO","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"Yes, air is needed to form any oxide.","correct":false},{"id":"b","text":"No, air must be kept out.","correct":true},{"id":"c","text":"It makes no difference.","correct":false}],"question":"Predict: when we heat the compound to get FeO, should air be present?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"To make iron (II) oxide, FeO, we heat a compound until it breaks down. The twist: FeO is easily oxidized in hot air."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Keep the air out?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{FeC2O4(s) ->[\\Delta][\\text{in absence of air}]}\\\\ \\ce{FeO(s) + CO(g) + CO2(g)}\\end{gathered}"},"children":[]},"k":{"type":"KeyTerm","props":{"term_en":"Iron (II) oxalate","definition":"$\\ce{FeC2O4}$, an iron (II) salt. The book draws it as two COO groups joined to Fe."},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"This is a thermal decomposition. Heating in absence of air keeps the FeO from being oxidized."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","f","t","m"]}}},"title":"Preparation 1: heating iron(II) oxalate"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["$\\ce{Fe2O3}$ holds 2 Fe atoms, so 2 FeO form.","2 FeO hold 2 O atoms; $\\ce{Fe2O3}$ had 3. The extra O joins $\\ce{H2}$ as $\\ce{H2O}$.","Hydrogen removes oxygen: it is the reducing agent."],"ordered":true},"children":[]},"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Fe2O3(s) + H2(g) ->[400-700\\,^{\\circ}C]}\\\\ \\ce{2FeO(s) + H2O(v)}\\end{gathered}"},"children":[]},"r":{"type":"Reveal","props":{"label":"Why 2FeO?"},"children":["b"]},"t":{"type":"Text","props":{"content":"FeO is also made by reduction of higher oxides by hydrogen or carbon monoxide."},"children":[]},"t2":{"type":"Text","props":{"muted":true,"content":"Higher oxides have more oxygen per iron atom: $\\ce{Fe2O3}$ and $\\ce{Fe3O4}$."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","t2","f","r"]}}},"title":"Preparation 2: reducing higher oxides"},{"id":"s4","kind":"interact","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"x":{"type":"EquationBuilder","props":{"prompt":"Reduce magnetic iron oxide, $\\ce{Fe3O4}$, with hydrogen at 400–700 °C. Balance the equation.","answers":[1,1,3,1],"template":"\\ce{{?}Fe3O4 + {?}H2 ->[400-700\\,^{\\circ}C] {?}FeO + {?}H2O}"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["x","h"]}}},"title":"Your turn: from Fe₃O₄"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["It is black powder, insoluble in water.","It is easily oxidized in hot air:"]},"children":[]},"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{4FeO(s) + O2(g) ->[\\Delta]}\\\\ \\ce{2Fe2O3(s)}\\end{gathered}"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"This is why its preparation needs absence of air."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","f","t","m"]}}},"title":"Properties: black, and easily oxidized"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{FeO(s) + H2SO4(aq) ->[(\\text{dil.})]}\\\\ \\ce{FeSO4(aq) + H2O(l)}\\end{gathered}"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"It reacts with mineral acids forming iron (II) salts and water."},"children":[]},"t2":{"type":"Text","props":{"content":"FeO is a basic oxide: acid + basic oxide → salt + water. No gas forms."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","t2","m"]}}},"title":"With dilute acids: an iron(II) salt"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"f":{"type":"FillBlank","props":{"text":"FeO + 2HCl → ___ + $\\ce{H2O}$","answers":[["FeCl2","FeCl₂","iron(II) chloride","iron (II) chloride"]],"mistakes":[{"id":"m1","blank":0,"answer":"FeCl3"},{"id":"m2","blank":0,"answer":"FeCl"},{"id":"m3","blank":0,"answer":"Fe2Cl"}]},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"The FeO formed was oxidized by hot air to $\\ce{Fe2O3}$.","correct":true},{"id":"b","text":"FeO is red, so the experiment worked.","correct":false},{"id":"c","text":"Iron (II) oxalate does not decompose on heating.","correct":false},{"id":"d","text":"Hot air reduced the FeO.","correct":false}],"question":"A student heats iron (II) oxalate in an open dish, in air. A red powder is left, not a black one. Why?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","q"]}}},"title":"Your turn"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Prepare FeO by heating iron (II) oxalate in absence of air.","Or reduce $\\ce{Fe2O3}$ or $\\ce{Fe3O4}$ with hydrogen or CO at 400–700 °C.","FeO is a black powder, insoluble in water, easily oxidized in hot air.","FeO + dilute acid → iron (II) salt + water."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rt":{"type":"Text","props":{"content":"Nothing is oxidized: iron is +2 in FeO and stays +2 in the salt. FeO is a basic oxide, so acid + FeO → iron (II) salt + water, e.g. $\\ce{FeSO4}$ with dilute $\\ce{H2SO4}$."},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rt"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why FeO gives an iron (II) salt, not an iron (III) salt, with a dilute acid?"},"children":[]}}},"title":"Summary"}],"title":"Iron(II) oxide FeO","minutes":8,"book_ref":"Ch.1 Iron oxides 1 (iron (II) oxide), p.22; Evaluation Q1.4-Q1.5, p.25","subtitle":"A black oxide that must be kept from hot air","objectives":["Describe two ways to prepare FeO, with their conditions.","Describe the properties of FeO.","Write its reactions with hot air and with dilute acids."],"concept_ids":["fe.oxide-feo"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"FeO's oxygen can come from the compound itself, and hot air would oxidize fresh FeO."},{"id":"b","feedback":"Good thinking. Hot air would oxidize the FeO as it forms."},{"id":"c","feedback":"At high temperature, air is not just a background: its oxygen can oxidize the fresh product."}],"explanation":"Air must be kept out: FeO is easily oxidized in hot air to $\\ce{Fe2O3}$. That is why the book heats iron (II) oxalate in absence of air; the oxygen in FeO comes from the compound itself."}},"s2":{"m":{"statement":"Heating iron (II) oxalate in air gives FeO.","correction":"Hot air would oxidize the FeO to $\\ce{Fe2O3}$, so air must be absent."}},"s4":{"h":{"hints":["How many Fe atoms are in $\\ce{Fe3O4}$? Each FeO holds one.","Count O: how many does FeO keep, and how many are left over?","Each leftover O needs one $\\ce{H2}$ to make water."]},"x":{"explanation":"3 Fe give 3 FeO. 4 O − 3 O leaves 1 O for one $\\ce{H2O}$."}},"s5":{"m":{"statement":"FeO is red.","correction":"FeO is a black powder. The red oxide is $\\ce{Fe2O3}$, the compound in hematite."}},"s6":{"m":{"statement":"FeO + dilute acid gives an iron (III) salt.","correction":"Nothing is oxidized here: iron is +2 in FeO and stays +2 in $\\ce{FeSO4}$."}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"Iron is +2 in FeO, and the acid does not change its oxidation state here."},{"id":"m2","feedback":"Iron is +2 and Cl is −1, so one Cl cannot balance one Fe."},{"id":"m3","feedback":"Iron is +2 and Cl is −1, so the subscript belongs on Cl, not on Fe."}],"explanation":"Iron stays +2: iron (II) chloride, $\\ce{FeCl2}$, and water."},"q":{"options":[{"id":"a","feedback":"Right. That is why the book heats it in absence of air."},{"id":"b","feedback":"FeO is a black powder, but the powder in the dish is red."},{"id":"c","feedback":"Something did change: a new powder was left, so the oxalate did decompose."},{"id":"d","feedback":"Air supplies oxygen, and gaining oxygen is oxidation, not reduction."}],"explanation":"Heating in air oxidized the FeO as it formed: $\\ce{4FeO + O2 -> 2Fe2O3}$. FeO is a black powder and $\\ce{Fe2O3}$ is red, which is why the book heats iron (II) oxalate in absence of air."}},"s8":{"e":{"body":"Give reason: iron (II) oxalate is heated in absence of air to prepare FeO. Key words: FeO is easily oxidized in hot air."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ oxygen اللي في الـ FeO ممكن ييجي من الـ compound نفسه، فمش لازم هوا عشان يتكوّن."},{"id":"b","feedback":"تفكير حلو. الهوا السخن كان هيعمل oxidation للـ FeO وهو بيتكوّن."},{"id":"c","feedback":"في درجة الحرارة العالية الهوا مش مجرد خلفية: فيه oxygen ممكن يتفاعل مع الناتج اللي لسه طالع."}],"explanation":"لازم نمنع الهوا: الـ FeO بيحصله oxidation بسهولة في الهوا السخن ويبقى $\\ce{Fe2O3}$. وعشان كده الكتاب بيسخّن الـ iron (II) oxalate في غياب الهوا؛ والـ oxygen اللي في الـ FeO جاي من الـ compound نفسه."}},"s2":{"m":{"statement":"تسخين الـ iron (II) oxalate في الهوا بيدّي FeO.","correction":"الهوا السخن هيعمل oxidation للـ FeO ويحوّله لـ $\\ce{Fe2O3}$، عشان كده لازم التسخين يبقى في غياب الهوا."}},"s4":{"h":{"hints":["كام ذرة Fe في الـ $\\ce{Fe3O4}$؟ كل FeO فيه ذرة واحدة.","عدّ الـ O: الـ FeO بياخد كام، وكام بيفضلوا زيادة؟","كل O زيادة محتاجة $\\ce{H2}$ واحد عشان تعمل مية."]},"x":{"explanation":"الـ 3 Fe بيدّوا 3 FeO. و4 O − 3 O يفضل 1 O لـ $\\ce{H2O}$ واحد."}},"s5":{"m":{"statement":"الـ FeO لونه أحمر.","correction":"الـ FeO مسحوق أسود. الـ oxide الأحمر هو الـ $\\ce{Fe2O3}$، الـ compound اللي في الـ hematite."}},"s6":{"m":{"statement":"الـ FeO مع الـ dilute acid بيدّي iron (III) salt.","correction":"مفيش oxidation هنا: الـ iron حالته +2 في الـ FeO وبيفضل +2 في الـ $\\ce{FeSO4}$."}},"s7":{"f":{"mistakes":[{"id":"m1","feedback":"الـ iron في الـ FeO حالته +2، والـ acid هنا مش بيغيّرها."},{"id":"m2","feedback":"الـ iron +2 والـ Cl −1، فـ Cl واحد مش كفاية يوازن Fe واحد."},{"id":"m3","feedback":"الـ iron +2 والـ Cl −1، فالـ Cl هو اللي محتاج الرقم الصغير (subscript)، مش الـ Fe."}],"explanation":"الـ iron بيفضل +2: يعني iron (II) chloride، $\\ce{FeCl2}$، ومية."},"q":{"options":[{"id":"a","feedback":"صح. وعشان كده الكتاب بيسخّنه في غياب الهوا."},{"id":"b","feedback":"الـ FeO مسحوق أسود، والمسحوق اللي فضل في الطبق أحمر."},{"id":"c","feedback":"فيه حاجة اتغيرت فعلًا: فضل مسحوق جديد لونه أحمر."},{"id":"d","feedback":"الهوا بيدّي oxygen، ولما مادة تكسب oxygen ده oxidation، مش reduction."}],"explanation":"التسخين في الهوا عمل oxidation للـ FeO وهو بيتكوّن: $\\ce{4FeO + O2 -> 2Fe2O3}$. الـ FeO مسحوق أسود والـ $\\ce{Fe2O3}$ أحمر، وعشان كده الكتاب بيسخّن الـ iron (II) oxalate في غياب الهوا."}},"s8":{"e":{"body":"Give reason: بنسخّن الـ iron (II) oxalate in absence of air عشان نحضّر FeO. الكلام المهم في الإجابة: الـ FeO is easily oxidized in hot air."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":1,"lesson_no":1,"lesson_count":4,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-oxides","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron 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metal","correct":false},{"id":"d","text":"FeS","correct":false}],"question":"Predict: what is the red solid?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Heat iron (II) sulphate, $\\ce{FeSO4}$, strongly. Two gases leave, and a red solid stays behind."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"What is left after heating?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{FeCl3(aq) + 3NH4OH(aq) ->}\\\\ \\ce{Fe(OH)3(s) v + 3NH4Cl(aq)}\\end{gathered}"},"children":[]},"t":{"type":"Text","props":{"content":"On adding an alkali to an aqueous solution of iron (III) salts, the (reddish brown) iron (III) hydroxide precipitates."},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a","label":"+ alkali"},{"to":"c","from":"b","label":"above 200 °C"}],"nodes":[{"id":"a","label":"$\\ce{FeCl3}$ solution"},{"id":"b","label":"$\\ce{Fe(OH)3}$, reddish brown"},{"id":"c","label":"$\\ce{Fe2O3}$"}],"caption":"The whole route; the second arrow comes next."},"children":[]},"t2":{"type":"Text","props":{"content":"Partners swap: a double displacement. $\\ce{Fe(OH)3}$ does not dissolve, so it precipitates."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","f","t2","fl"]}}},"title":"Preparation 1: from an iron(III) salt"},{"id":"s3","kind":"interact","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Heating iron (III) hydroxide above 200 °C converts it to iron (III) oxide."},"children":[]},"x":{"type":"EquationBuilder","props":{"prompt":"Balance the equation.","answers":[2,1,3],"template":"\\ce{{?}Fe(OH)3 ->[\\text{above }200\\,^{\\circ}C] {?}Fe2O3 + {?}H2O}"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","x","h"]}}},"title":"Heat the hydroxide"},{"id":"s4","kind":"explain","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["2 S on the left: one leaves in SO₂, one in SO₃.","Iron is oxidized: +2 → +3.","To pay for that, one S is reduced: +6 → +4 in SO₂. The other S stays +6 in SO₃."]},"children":[]},"f":{"type":"Formula","props":{"latex":"\\ce{2FeSO4(s) ->[\\Delta] Fe2O3(s) + SO2(g) + SO3(g)}"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"r":{"type":"Reveal","props":{"label":"Why two gases?"},"children":["b"]},"t":{"type":"Text","props":{"content":"Two gases leave: sulphur dioxide and sulphur trioxide."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","m","r"]}}},"title":"Preparation 2: heating iron(II) sulphate"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["This oxide is present in nature in the form of hematite.","It is insoluble in water.","It is used in red pigments in paints."]},"children":[]},"t":{"type":"Text","props":{"muted":true,"content":"Hematite is the red iron ore you met in the extraction unit."},"children":[]},"tb":{"type":"DataTable","props":{"rows":[["Found in nature as","hematite"],["In water","insoluble"],["Used in","red pigments in paints"]],"headers":["Property","Iron (III) oxide"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","tb","t"]}}},"title":"In nature and in paints"},{"id":"s6","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Fe2O3(s) + 3H2SO4(aq) ->[\\Delta][\\text{conc.}]}\\\\ \\ce{Fe2(SO4)3(aq) + 3H2O(v)}\\end{gathered}"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"It reacts with hot conc. mineral acids to form iron (III) salts and water."},"children":[]},"t2":{"type":"Text","props":{"content":"Iron stays +3, so the salt is an iron (III) salt. No gas forms."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","t2","m"]}}},"title":"With hot concentrated acids"},{"id":"s7","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"A reddish brown precipitate of $\\ce{Fe(OH)3}$","correct":true},{"id":"b","text":"$\\ce{Fe2O3}$ directly","correct":false},{"id":"c","text":"Hydrogen gas","correct":false},{"id":"d","text":"Nothing: only $\\ce{FeCl3}$ gives this precipitate","correct":false}],"question":"An alkali is added to iron (III) nitrate solution, $\\ce{Fe(NO3)3}$. What forms first?"},"children":[]},"x":{"type":"EquationBuilder","props":{"prompt":"Balance $\\ce{Fe2O3}$ with hot concentrated hydrochloric acid.","answers":[1,6,2,3],"template":"\\ce{{?}Fe2O3 + {?}HCl ->[\\Delta][\\text{conc.}] {?}FeCl3 + {?}H2O}"},"children":[]},"tf":{"type":"TrueFalse","props":{"answer":false,"statement":"Heating iron (II) sulphate gives FeO and $\\ce{SO3}$ only."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["x","q","tf"]}}},"title":"Your turn"},{"id":"s8","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Alkali + iron (III) salt → reddish brown $\\ce{Fe(OH)3}$; above 200 °C → $\\ce{Fe2O3}$ + water.","Heating $\\ce{FeSO4}$ → $\\ce{Fe2O3}$ + $\\ce{SO2}$ + $\\ce{SO3}$.","Found as hematite; insoluble in water; used in red pigments in paints.","Hot conc. acid + $\\ce{Fe2O3}$ → iron (III) salt + water."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rt":{"type":"Text","props":{"content":"Iron is oxidized from +2 to +3. To pay for that, one S is reduced from +6 to +4 and leaves in $\\ce{SO2}$; the other S stays +6 and leaves in $\\ce{SO3}$."},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rt"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why heating $\\ce{FeSO4}$ gives two different sulphur gases?"},"children":[]}}},"title":"Summary"}],"title":"Iron(III) oxide Fe₂O₃","minutes":8,"book_ref":"Ch.1 Iron oxides 2 (iron (III) oxide), pp.22-23; Evaluation Q1.6, p.25","subtitle":"The red oxide: two ways to make it","objectives":["Describe two ways to prepare $\\ce{Fe2O3}$, with their equations and conditions.","State where $\\ce{Fe2O3}$ occurs and its use.","Write the reaction of $\\ce{Fe2O3}$ with hot concentrated acids."],"concept_ids":["fe.oxide-fe2o3"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"FeO is black, but this solid is red, so it is not FeO."},{"id":"b","feedback":"Good thinking. Iron (II) is oxidized to iron (III) here."},{"id":"c","feedback":"Iron metal is grey, and nothing here removes the oxygen."},{"id":"d","feedback":"Here the sulphur leaves in the gases, so FeS cannot stay behind."}],"explanation":"The red solid is $\\ce{Fe2O3}$: $\\ce{2FeSO4 -> Fe2O3 + SO2 + SO3}$. Iron (II) is oxidized to iron (III), and the sulphur leaves in the two gases."}},"s3":{"h":{"hints":["How many Fe atoms does $\\ce{Fe2O3}$ need?","Count the H atoms in that many $\\ce{Fe(OH)3}$. Each $\\ce{H2O}$ takes two."]},"x":{"explanation":"$\\ce{Fe2O3}$ needs 2 Fe: 2 $\\ce{Fe(OH)3}$. Their 6 H leave as 3 $\\ce{H2O}$."}},"s4":{"m":{"statement":"Heating $\\ce{FeSO4}$ gives FeO, or only $\\ce{SO2}$.","correction":"Iron ends at +3 in $\\ce{Fe2O3}$, and the sulphur leaves as both $\\ce{SO2}$ and $\\ce{SO3}$."}},"s6":{"m":{"statement":"$\\ce{Fe2O3}$ reacts with cold dilute acids, like FeO.","correction":"$\\ce{Fe2O3}$ reacts slowly, so the book uses hot concentrated acids. Keep those conditions."}},"s7":{"q":{"options":[{"id":"a","feedback":"Right. Any iron (III) salt gives this precipitate with an alkali."},{"id":"b","feedback":"The oxide needs one more step: it forms only after the hydroxide is heated."},{"id":"c","feedback":"An alkali and a salt swap partners; no metal displaces hydrogen here."},{"id":"d","feedback":"The book says iron (III) salts in general, and iron (III) nitrate is one of them."}],"explanation":"A reddish brown precipitate of $\\ce{Fe(OH)3}$ forms first: an alkali gives this precipitate with an aqueous solution of iron (III) salts, and iron (III) nitrate is one of them. The oxide forms only after the hydroxide is heated above 200 °C."},"x":{"explanation":"2 Fe give 2 $\\ce{FeCl3}$: 6 Cl, so 6 HCl. 6 H make 3 $\\ce{H2O}$."},"tf":{"explanation":"The statement is false: heating iron (II) sulphate gives $\\ce{Fe2O3}$, $\\ce{SO2}$ and $\\ce{SO3}$, so the red oxide is left and two gases leave.","feedback_true":"The oxide left is the red one, not black FeO, and more than one gas leaves.","feedback_false":"Right. It gives $\\ce{Fe2O3}$, $\\ce{SO2}$ and $\\ce{SO3}$."}},"s8":{"e":{"body":"MCQ (Q1.6): heating iron (II) sulphate produces iron (III) oxide, sulphur dioxide and sulphur trioxide."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"الـ FeO لونه أسود، لكن المادة الصلبة دي لونها أحمر."},{"id":"b","feedback":"تفكير حلو. الـ iron (II) هنا بيتأكسد (oxidized) ويبقى iron (III)."},{"id":"c","feedback":"الـ iron metal لونه رمادي، ومفيش حاجة هنا بتشيل الـ oxygen."},{"id":"d","feedback":"هنا الـ sulphur بيطلع مع الغازات، فالـ FeS مايقدرش يفضل في الآخر."}],"explanation":"المادة الصلبة الحمرا هي $\\ce{Fe2O3}$: $\\ce{2FeSO4 -> Fe2O3 + SO2 + SO3}$. الـ iron (II) بيتأكسد (oxidized) ويبقى iron (III)، والـ sulphur بيطلع مع الغازين."}},"s3":{"h":{"hints":["الـ $\\ce{Fe2O3}$ محتاج كام ذرة Fe؟","عدّ ذرات الـ H في العدد ده من الـ $\\ce{Fe(OH)3}$. وكل $\\ce{H2O}$ بياخد اتنين."]},"x":{"explanation":"الـ $\\ce{Fe2O3}$ محتاج 2 Fe، يعني 2 $\\ce{Fe(OH)3}$. والـ 6 H اللي فيهم بيطلعوا على شكل 3 $\\ce{H2O}$."}},"s4":{"m":{"statement":"تسخين الـ $\\ce{FeSO4}$ بيدّي FeO، أو بيطلّع $\\ce{SO2}$ لوحده.","correction":"الـ iron بيخلص عند +3 في الـ $\\ce{Fe2O3}$، والـ sulphur بيطلع في صورة $\\ce{SO2}$ و $\\ce{SO3}$ الاتنين."}},"s6":{"m":{"statement":"الـ $\\ce{Fe2O3}$ بيتفاعل مع الـ dilute acids الباردة زي الـ FeO.","correction":"الـ $\\ce{Fe2O3}$ تفاعله بطيء، عشان كده الكتاب بيستخدم acids مركّزة وسخنة. خلّي الشروط دي معاك."}},"s7":{"q":{"options":[{"id":"a","feedback":"صح. أي iron (III) salt بيدّي الـ precipitate ده مع الـ alkali."},{"id":"b","feedback":"الـ oxide محتاج خطوة كمان: الـ hydroxide لازم يتسخّن الأول."},{"id":"c","feedback":"الـ alkali والـ salt بيبدّلوا الشركا، ومفيش metal هنا بيطرد الـ hydrogen."},{"id":"d","feedback":"الكتاب بيقول iron (III) salts، والـ iron (III) nitrate واحد منهم."}],"explanation":"اللي بيتكوّن الأول هو precipitate لونه reddish brown من الـ $\\ce{Fe(OH)3}$: الـ alkali بيدّي الـ precipitate ده مع محلول الـ iron (III) salts، والـ iron (III) nitrate واحد منهم. والـ oxide مش بيتكوّن غير بعد ما الـ hydroxide يتسخّن فوق 200 °C."},"x":{"explanation":"الـ 2 Fe بيدّوا 2 $\\ce{FeCl3}$: يعني 6 Cl، فمحتاجين 6 HCl. والـ 6 H بيعملوا 3 $\\ce{H2O}$."},"tf":{"explanation":"الجملة دي false: تسخين الـ iron (II) sulphate بيدّي $\\ce{Fe2O3}$ و $\\ce{SO2}$ و $\\ce{SO3}$، يعني الـ oxide الأحمر هو اللي بيفضل وبيطلع غازين.","feedback_true":"الـ iron oxide اللي بيفضل هو الأحمر مش الأسود، وبيطلع غازين مش غاز واحد.","feedback_false":"صح. بيدّي $\\ce{Fe2O3}$ و $\\ce{SO2}$ و $\\ce{SO3}$."}},"s8":{"e":{"body":"MCQ (Q1.6): تسخين الـ iron (II) sulphate بيدّي iron (III) oxide و sulphur dioxide و sulphur trioxide."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":2,"lesson_no":2,"lesson_count":4,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-oxides","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron oxides","duration_s":651.119,"start_s":203.9,"end_s":294.6,"ord":0,"in_release":true,"content_lang":"ar-EG"},"see_also":[{"item_id":"chem-s3-en.video-short-fe.oxide-fe2o3","kind":"short","chapter_id":"chem-s3-en.ch1","title":"Iron(III) oxide Fe₂O₃","duration_s":52.63,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"exercise":"Question 1","question":"6","relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.oxide-fe3o4","kind":"lesson","version":3,"catalog_version":3,"ord":498,"primary_concept_id":"fe.oxide-fe3o4","concepts":[{"concept_id":"fe.oxide-fe3o4","role":"primary"}],"title":"Magnetic iron oxide Fe₃O₄","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"One: iron (III) sulphate only","correct":false},{"id":"b","text":"Two: iron (II) and iron (III) sulphates","correct":true},{"id":"c","text":"None: it does not react with acids","correct":false}],"question":"Predict: how many different iron salts form?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Magnetite, $\\ce{Fe3O4}$, is a black ore that sticks to a magnet. Now heat it with concentrated sulphuric acid."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"One oxide, two salts?"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"k":{"type":"KeyTerm","props":{"term_en":"Mixed oxide","definition":"$\\ce{Fe3O4}$ can be considered as mixed iron (II) and iron (III) oxides: FeO + $\\ce{Fe2O3}$."},"children":[]},"t":{"type":"Text","props":{"content":"It is known naturally as magnetite. It is a strong magnet."},"children":[]},"tab":{"type":"DataTable","props":{"rows":[["Fe atoms","1","2","3"],["O atoms","1","3","4"]],"caption":"FeO + Fe₂O₃ add up to Fe₃O₄","headers":["","FeO","Fe₂O₃","Together"]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["k","tab","t"]}}},"title":"A mixed oxide"},{"id":"s3","kind":"explain","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["By the action of hot air or steam on red hot iron.","By reduction of iron (III) oxide with carbon monoxide:"],"ordered":true},"children":[]},"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{3Fe2O3(s) + CO(g) ->[230-300\\,^{\\circ}C]}\\\\ \\ce{2Fe3O4(s) + CO2(g)}\\end{gathered}"},"children":[]},"t":{"type":"Text","props":{"muted":true,"content":"You met route 1 in 'Effect of air and water vapour'."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","f","t"]}}},"title":"Preparation"},{"id":"s4","kind":"interact","spec":{"root":"root","state":{"r":1},"elements":{"m":{"type":"Misconception","props":{},"children":[]},"s":{"type":"Slider","props":{"max":3,"min":1,"step":1,"label":"Rung","value":{"$bindState":"/r"}},"children":[]},"t":{"type":"Text","props":{"content":"Reduce the same oxide, $\\ce{Fe2O3}$, at different temperatures. Move up the thermometer."},"children":[]},"d1":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 270\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"43\" y=\"10\" width=\"18\" height=\"200\" rx=\"9\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><circle cx=\"52\" cy=\"226\" r=\"16\" fill=\"#f87171\" fill-opacity=\"0.8\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><rect x=\"48\" y=\"160\" width=\"8\" height=\"54\" fill=\"#f87171\" fill-opacity=\"0.8\"/><line x1=\"64\" y1=\"172\" x2=\"82\" y2=\"172\" stroke=\"#fbbf24\" stroke-width=\"2.5\"/><text x=\"88\" y=\"168\" font-size=\"14\" fill=\"#fbbf24\" text-anchor=\"start\" font-weight=\"700\">230–300 °C</text><text x=\"88\" y=\"186\" font-size=\"12\" fill=\"#e2e8f0\" text-anchor=\"start\" font-weight=\"500\">Fe₂O₃ + CO</text><line x1=\"232.0\" y1=\"176.0\" x2=\"266.0\" y2=\"176.0\" stroke=\"#fbbf24\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"266.0,176.0 258.8,179.5 258.8,172.5\" fill=\"#fbbf24\"/><text x=\"274\" y=\"182\" font-size=\"20\" fill=\"#34d399\" text-anchor=\"start\" font-weight=\"700\">Fe₃O₄</text><line x1=\"64\" y1=\"112\" x2=\"82\" y2=\"112\" stroke=\"#94a3b8\" stroke-width=\"2.5\"/><text x=\"88\" y=\"108\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">400–700 °C</text><text x=\"88\" y=\"126\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">Fe₂O₃ + H₂ or CO</text><line x1=\"232.0\" y1=\"116.0\" x2=\"266.0\" y2=\"116.0\" stroke=\"#94a3b8\" stroke-width=\"1.4\" stroke-linecap=\"round\"/><polygon points=\"266.0,116.0 258.8,119.5 258.8,112.5\" fill=\"#94a3b8\"/><text x=\"274\" y=\"122\" font-size=\"15\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"700\">FeO</text><line x1=\"64\" y1=\"42\" x2=\"82\" y2=\"42\" stroke=\"#94a3b8\" stroke-width=\"2.5\"/><text x=\"88\" y=\"38\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">higher than 700 °C</text><text x=\"88\" y=\"56\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">Fe₂O₃ + CO</text><line x1=\"232.0\" y1=\"46.0\" x2=\"266.0\" y2=\"46.0\" stroke=\"#94a3b8\" stroke-width=\"1.4\" stroke-linecap=\"round\"/><polygon points=\"266.0,46.0 258.8,49.5 258.8,42.5\" fill=\"#94a3b8\"/><text x=\"274\" y=\"52\" font-size=\"15\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"700\">Fe</text><text x=\"88\" y=\"236\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">cooler</text><text x=\"88\" y=\"8\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">hotter</text></svg>","max_width":380},"visible":{"eq":1,"$state":"/r"},"children":[]},"d2":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -10 360 270\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"43\" y=\"10\" width=\"18\" height=\"200\" rx=\"9\" fill=\"none\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><circle cx=\"52\" cy=\"226\" r=\"16\" fill=\"#f87171\" fill-opacity=\"0.8\" stroke=\"#e2e8f0\" stroke-width=\"2.5\"/><rect x=\"48\" y=\"100\" width=\"8\" height=\"114\" fill=\"#f87171\" fill-opacity=\"0.8\"/><line x1=\"64\" y1=\"172\" x2=\"82\" y2=\"172\" stroke=\"#94a3b8\" stroke-width=\"2.5\"/><text x=\"88\" y=\"168\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">230–300 °C</text><text x=\"88\" y=\"186\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">Fe₂O₃ + CO</text><line x1=\"232.0\" y1=\"176.0\" x2=\"266.0\" y2=\"176.0\" stroke=\"#94a3b8\" stroke-width=\"1.4\" stroke-linecap=\"round\"/><polygon points=\"266.0,176.0 258.8,179.5 258.8,172.5\" fill=\"#94a3b8\"/><text x=\"274\" y=\"182\" font-size=\"15\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"700\">Fe₃O₄</text><line x1=\"64\" y1=\"112\" x2=\"82\" y2=\"112\" stroke=\"#fbbf24\" stroke-width=\"2.5\"/><text x=\"88\" y=\"108\" font-size=\"14\" fill=\"#fbbf24\" text-anchor=\"start\" font-weight=\"700\">400–700 °C</text><text x=\"88\" y=\"126\" font-size=\"12\" fill=\"#e2e8f0\" text-anchor=\"start\" font-weight=\"500\">Fe₂O₃ + H₂ or CO</text><line x1=\"232.0\" y1=\"116.0\" x2=\"266.0\" y2=\"116.0\" stroke=\"#fbbf24\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"266.0,116.0 258.8,119.5 258.8,112.5\" fill=\"#fbbf24\"/><text x=\"274\" y=\"122\" font-size=\"20\" fill=\"#34d399\" text-anchor=\"start\" font-weight=\"700\">FeO</text><line x1=\"64\" y1=\"42\" x2=\"82\" y2=\"42\" stroke=\"#94a3b8\" stroke-width=\"2.5\"/><text x=\"88\" y=\"38\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">higher than 700 °C</text><text x=\"88\" y=\"56\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">Fe₂O₃ + CO</text><line x1=\"232.0\" y1=\"46.0\" x2=\"266.0\" y2=\"46.0\" stroke=\"#94a3b8\" stroke-width=\"1.4\" stroke-linecap=\"round\"/><polygon points=\"266.0,46.0 258.8,49.5 258.8,42.5\" fill=\"#94a3b8\"/><text 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fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">230–300 °C</text><text x=\"88\" y=\"186\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">Fe₂O₃ + CO</text><line x1=\"232.0\" y1=\"176.0\" x2=\"266.0\" y2=\"176.0\" stroke=\"#94a3b8\" stroke-width=\"1.4\" stroke-linecap=\"round\"/><polygon points=\"266.0,176.0 258.8,179.5 258.8,172.5\" fill=\"#94a3b8\"/><text x=\"274\" y=\"182\" font-size=\"15\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"700\">Fe₃O₄</text><line x1=\"64\" y1=\"112\" x2=\"82\" y2=\"112\" stroke=\"#94a3b8\" stroke-width=\"2.5\"/><text x=\"88\" y=\"108\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">400–700 °C</text><text x=\"88\" y=\"126\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">Fe₂O₃ + H₂ or CO</text><line x1=\"232.0\" y1=\"116.0\" x2=\"266.0\" y2=\"116.0\" stroke=\"#94a3b8\" stroke-width=\"1.4\" stroke-linecap=\"round\"/><polygon points=\"266.0,116.0 258.8,119.5 258.8,112.5\" fill=\"#94a3b8\"/><text x=\"274\" y=\"122\" font-size=\"15\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"700\">FeO</text><line x1=\"64\" y1=\"42\" x2=\"82\" y2=\"42\" stroke=\"#fbbf24\" stroke-width=\"2.5\"/><text x=\"88\" y=\"38\" font-size=\"14\" fill=\"#fbbf24\" text-anchor=\"start\" font-weight=\"700\">higher than 700 °C</text><text x=\"88\" y=\"56\" font-size=\"12\" fill=\"#e2e8f0\" text-anchor=\"start\" font-weight=\"500\">Fe₂O₃ + CO</text><line x1=\"232.0\" y1=\"46.0\" x2=\"266.0\" y2=\"46.0\" stroke=\"#fbbf24\" stroke-width=\"2.2\" stroke-linecap=\"round\"/><polygon points=\"266.0,46.0 258.8,49.5 258.8,42.5\" fill=\"#fbbf24\"/><text x=\"274\" y=\"52\" font-size=\"20\" fill=\"#34d399\" text-anchor=\"start\" font-weight=\"700\">Fe</text><text x=\"88\" y=\"236\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">cooler</text><text x=\"88\" y=\"8\" font-size=\"12\" fill=\"#94a3b8\" text-anchor=\"start\" font-weight=\"500\">hotter</text></svg>","max_width":380},"visible":{"eq":3,"$state":"/r"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","s","d1","d2","d3","m"]}}},"title":"The thermometer ladder"},{"id":"s5","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Fe3O4 + 4H2SO4 ->[\\text{conc.}][\\Delta]}\\\\ \\ce{FeSO4 + Fe2(SO4)3 + 4H2O}\\end{gathered}"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"It reacts with hot concentrated acids to give iron (II) and iron (III) salts, proving that it is a mixed oxide."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","m"]}}},"title":"With hot concentrated acids: two salts"},{"id":"s6","kind":"example","spec":{"root":"root","elements":{"t":{"type":"Text","props":{"content":"Add them. FeO + $\\ce{Fe2O3}$ = $\\ce{Fe3O4}$, and 1 + 3 = 4 $\\ce{H2SO4}$."},"children":[]},"f1":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{FeO + H2SO4 ->}\\\\ \\ce{FeSO4 + H2O}\\end{gathered}","caption":"FeO part"},"children":[]},"f2":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Fe2O3 + 3H2SO4 ->}\\\\ \\ce{Fe2(SO4)3 + 3H2O}\\end{gathered}","caption":"Fe₂O₃ part"},"children":[]},"f3":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{Fe3O4 + 4H2SO4 ->}\\\\ \\ce{FeSO4 + Fe2(SO4)3 + 4H2O}\\end{gathered}","caption":"Sum = the book's equation"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f1","f2","t","f3"]}}},"title":"Worked: add the two parts"},{"id":"s7","kind":"explain","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\begin{gathered}\\ce{2Fe3O4(s) + 1/2O2(g) ->[\\Delta]}\\\\ \\ce{3Fe2O3(s)}\\end{gathered}"},"children":[]},"t":{"type":"Text","props":{"content":"It is oxidized to iron (III) oxide when it is heated in air."},"children":[]},"t2":{"type":"Text","props":{"content":"Its iron (II) part is oxidized to iron (III)."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["f","t","t2"]}}},"title":"Heated in air"},{"id":"s8","kind":"check","spec":{"root":"root","elements":{"h":{"type":"HintLadder","props":{},"children":[]},"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"With hot concentrated acids it gives iron (II) and iron (III) salts.","correct":true},{"id":"b","text":"It is attracted by a magnet.","correct":false},{"id":"c","text":"It forms when steam passes over red hot iron.","correct":false},{"id":"d","text":"It is black.","correct":false}],"question":"Which result proves that $\\ce{Fe3O4}$ is a mixed oxide?"},"children":[]},"x":{"type":"EquationBuilder","props":{"prompt":"Now with hot concentrated hydrochloric acid. Balance it.","answers":[1,8,1,2,4],"template":"\\ce{{?}Fe3O4 + {?}HCl ->[\\text{conc.}][\\Delta] {?}FeCl2 + {?}FeCl3 + {?}H2O}"},"children":[]},"q2":{"type":"MCQ","props":{"options":[{"id":"a","text":"FeO","correct":true},{"id":"b","text":"Fe","correct":false},{"id":"c","text":"$\\ce{Fe2O3}$","correct":false},{"id":"d","text":"$\\ce{FeSO4}$","correct":false}],"question":"Magnetic iron oxide is reduced by hydrogen at 400–700 °C. What forms?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["x","h","q","q2"]}}},"title":"Your turn"},{"id":"s9","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["$\\ce{Fe3O4}$: black, a strong magnet, a mixed iron (II) and iron (III) oxide (magnetite).","Made by hot air or steam on red hot iron, or $\\ce{Fe2O3}$ + CO at 230–300 °C.","Hot conc. acids give iron (II) + iron (III) salts: proof it is mixed.","Heated in air, it is oxidized to $\\ce{Fe2O3}$."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rt":{"type":"Text","props":{"content":"$\\ce{Fe3O4}$ is a mixed oxide, FeO + $\\ce{Fe2O3}$: its FeO part gives the iron (II) salt and its $\\ce{Fe2O3}$ part gives the iron (III) salt. $\\ce{Fe2O3}$ is iron (III) oxide, so it gives one salt: an iron (III) salt."},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rt"]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why Fe₃O₄ gives two salts, but Fe₂O₃ only one?"},"children":[]}}},"title":"Summary"}],"title":"Magnetic iron oxide Fe₃O₄","minutes":9,"book_ref":"Ch.1 Iron oxides 3 (the black oxide), pp.23-24; Evaluation Q1.3-Q1.4, p.25","subtitle":"A mixed oxide: two salts prove it","objectives":["Explain why $\\ce{Fe3O4}$ is a mixed oxide, using its reaction with hot concentrated acids.","Describe how $\\ce{Fe3O4}$ is prepared and how it is oxidized in air, with conditions."],"concept_ids":["fe.oxide-fe3o4"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"One salt would mean the oxide holds only one kind of iron ion, and the reaction with acid has not shown that."},{"id":"b","feedback":"Good thinking. That result is the proof we will use."},{"id":"c","feedback":"Hot concentrated acids do attack it, so a reaction does happen."}],"explanation":"Two salts form, iron (II) sulphate and iron (III) sulphate. $\\ce{Fe3O4}$ reacts with hot concentrated acids to give both iron (II) and iron (III) salts, which shows it is a mixed oxide."}},"s4":{"m":{"statement":"Reducing $\\ce{Fe2O3}$ with CO always gives iron.","correction":"The temperature decides how much oxygen is removed: 230–300 °C gives $\\ce{Fe3O4}$."}},"s5":{"m":{"statement":"$\\ce{Fe3O4}$ is a single oxide that gives one salt.","correction":"Its FeO part gives the iron (II) salt; its $\\ce{Fe2O3}$ part gives the iron (III) salt."}},"s8":{"h":{"hints":["Split it: what does the FeO part give with HCl?","What does the $\\ce{Fe2O3}$ part give, and how many HCl does it use?","Add the two parts, as in the worked example."]},"q":{"options":[{"id":"a","feedback":"Right. Two salts show two oxidation states of iron."},{"id":"b","feedback":"Being magnetic does not show two oxidation states."},{"id":"c","feedback":"That is how it is prepared; it says nothing about the kinds of iron in it."},{"id":"d","feedback":"FeO is black too, so the colour cannot show iron (II) and iron (III) together."}],"explanation":"The proof is its reaction with hot concentrated acids: it gives iron (II) and iron (III) salts, so it holds iron in two oxidation states. Being magnetic, black, or made from red hot iron does not show that."},"x":{"explanation":"FeO part: 2 HCl. $\\ce{Fe2O3}$ part: 6 HCl. Total 8 HCl and 4 $\\ce{H2O}$."},"q2":{"options":[{"id":"a","feedback":"Right. The middle rung gives FeO."},{"id":"b","feedback":"Iron needs the top rung: higher than 700 °C with CO, not hydrogen at 400–700 °C."},{"id":"c","feedback":"Hydrogen removes oxygen, so it cannot give an oxide with more oxygen per iron."},{"id":"d","feedback":"A sulphate needs sulphuric acid, and the reagent here is hydrogen."}],"explanation":"Hydrogen at 400–700 °C reduces magnetic iron oxide to FeO: $\\ce{Fe3O4 + H2 -> 3FeO + H2O}$. Getting iron itself needs CO at a temperature higher than 700 °C."}},"s9":{"e":{"body":"MCQ (Q1.3): black iron oxide with hot conc. acids gives iron (II) and iron (III) salts together."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"salt واحد معناه إن الـ oxide فيه نوع واحد من الـ iron، ومفيش حاجة لحد دلوقتي بتثبت ده."},{"id":"b","feedback":"تفكير حلو. النتيجة دي هي الدليل اللي هنستخدمه."},{"id":"c","feedback":"الـ hot concentrated acids بتتفاعل معاه فعلًا وبتدّي salts."}],"explanation":"بيتكوّن 2 salts: الـ iron (II) sulphate والـ iron (III) sulphate. الـ $\\ce{Fe3O4}$ بيتفاعل مع الـ hot concentrated acids ويدّي iron (II) salts و iron (III) salts مع بعض، وده بيبيّن إنه mixed oxide."}},"s4":{"m":{"statement":"اختزال الـ $\\ce{Fe2O3}$ بالـ CO بيدّي iron على طول.","correction":"درجة الحرارة هي اللي بتحدد قد إيه oxygen هيتشال: عند 230–300 °C بيدّي $\\ce{Fe3O4}$."}},"s5":{"m":{"statement":"الـ $\\ce{Fe3O4}$ oxide واحد وبيدّي salt واحد.","correction":"الجزء الـ FeO اللي فيه بيدّي الـ iron (II) salt، والجزء الـ $\\ce{Fe2O3}$ بيدّي الـ iron (III) salt."}},"s8":{"h":{"hints":["قسّمه: جزء الـ FeO بيدّي إيه مع الـ HCl؟","وجزء الـ $\\ce{Fe2O3}$ بيدّي إيه، وبياخد كام HCl؟","اجمع الجزءين، زي ما عملنا في المثال المحلول."]},"q":{"options":[{"id":"a","feedback":"صح. 2 salts يعني الـ iron موجود بـ 2 oxidation states."},{"id":"b","feedback":"إنه magnetic ده مش بيبيّن 2 oxidation states."},{"id":"c","feedback":"دي طريقة تحضيره، ومش بتبيّن أنواع الـ iron اللي فيه."},{"id":"d","feedback":"الـ FeO أسود هو كمان، فاللون مش بيبيّن iron (II) و iron (III) مع بعض."}],"explanation":"الدليل هو تفاعله مع الـ hot concentrated acids: بيدّي iron (II) salts و iron (III) salts، يعني فيه iron بـ 2 oxidation states. إنه magnetic أو أسود أو بيتحضّر من الـ red hot iron، ده مش بيبيّن كده."},"x":{"explanation":"جزء الـ FeO: 2 HCl. جزء الـ $\\ce{Fe2O3}$: 6 HCl. المجموع 8 HCl و4 $\\ce{H2O}$."},"q2":{"options":[{"id":"a","feedback":"صح. الدرجة اللي في النص بتدّي FeO."},{"id":"b","feedback":"الـ iron محتاج الدرجة اللي فوق: أعلى من 700 °C مع الـ CO، مش الـ hydrogen عند 400–700 °C."},{"id":"c","feedback":"الـ hydrogen بيشيل oxygen، فمش هيدّي oxide فيه oxygen أكتر لكل iron."},{"id":"d","feedback":"الـ sulphate محتاج sulphuric acid، والـ reagent المستخدم هنا hydrogen."}],"explanation":"الـ hydrogen عند 400–700 °C بيعمل reduction للـ magnetic iron oxide ويدّي FeO: $\\ce{Fe3O4 + H2 -> 3FeO + H2O}$. أما عشان نوصل للـ iron نفسه فمحتاجين CO عند أعلى من 700 °C."}},"s9":{"e":{"body":"MCQ (Q1.3): الـ black iron oxide مع الـ hot conc. acids بيدّي iron (II) salts و iron (III) salts مع بعض."}}}},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":3,"lesson_no":3,"lesson_count":4,"lesson_video":{"item_id":"chem-s3-en.video-episode-fe-oxides","kind":"episode","chapter_id":"chem-s3-en.ch1","title":"Iron 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correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"exercise":"Question 1","question":"3","relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"exercise":"Question 1","question":"4","relation":"based_on"}]},{"id":"chem-s3-en.lesson-fe.conversions","kind":"lesson","version":2,"catalog_version":3,"ord":500,"primary_concept_id":"fe.conversions","concepts":[{"concept_id":"fe.conversions","role":"primary"}],"title":"Iron and its oxides: reaction diagrams","payload":{"level":"core","steps":[{"id":"s1","kind":"hook","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"No: the same reactants always give the same product.","correct":false},{"id":"b","text":"Yes: the temperature decides the product.","correct":true}],"question":"Predict: can CO and $\\ce{Fe2O3}$ give different products?"},"children":[]},"t":{"type":"Text","props":{"size":"lg","content":"Pass carbon monoxide over hot $\\ce{Fe2O3}$. Change only the temperature."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["t","q"]}}},"title":"Same reactants, different products"},{"id":"s2","kind":"explain","spec":{"root":"root","elements":{"d":{"type":"Diagram","props":{"svg":"<svg viewBox=\"0 -14 360 262\" xmlns=\"http://www.w3.org/2000/svg\" font-family=\"sans-serif\"><rect x=\"115\" y=\"-2\" width=\"130\" height=\"48\" rx=\"8\" fill=\"#94a3b8\" fill-opacity=\"0.18\" stroke=\"#e2e8f0\" stroke-width=\"1.8\"/><text x=\"180\" y=\"22\" font-size=\"17\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">Fe₂O₃</text><text x=\"180\" y=\"39\" font-size=\"11\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">iron +3</text><rect x=\"115\" y=\"58\" width=\"130\" height=\"48\" rx=\"8\" fill=\"#94a3b8\" fill-opacity=\"0.18\" stroke=\"#e2e8f0\" stroke-width=\"1.8\"/><text x=\"180\" y=\"82\" font-size=\"17\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">Fe₃O₄</text><text x=\"180\" y=\"99\" font-size=\"11\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">iron +2 and +3</text><rect x=\"115\" y=\"118\" width=\"130\" height=\"48\" rx=\"8\" fill=\"#94a3b8\" fill-opacity=\"0.18\" stroke=\"#e2e8f0\" stroke-width=\"1.8\"/><text x=\"180\" y=\"142\" font-size=\"17\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">FeO</text><text x=\"180\" y=\"159\" font-size=\"11\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">iron +2</text><rect x=\"115\" y=\"178\" width=\"130\" height=\"48\" rx=\"8\" fill=\"#94a3b8\" fill-opacity=\"0.18\" stroke=\"#e2e8f0\" stroke-width=\"1.8\"/><text x=\"180\" y=\"202\" font-size=\"17\" fill=\"#e2e8f0\" text-anchor=\"middle\" font-weight=\"700\">Fe</text><text x=\"180\" y=\"219\" font-size=\"11\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">the metal (0)</text><line x1=\"100.0\" y1=\"215.0\" x2=\"100.0\" y2=\"10.0\" stroke=\"#f87171\" stroke-width=\"2.6\" stroke-linecap=\"round\"/><polygon points=\"100.0,10.0 104.3,19.0 95.7,19.0\" fill=\"#f87171\"/><text x=\"90\" y=\"100\" font-size=\"13\" fill=\"#f87171\" text-anchor=\"end\" font-weight=\"700\">oxidation</text><text x=\"90\" y=\"117\" font-size=\"11\" fill=\"#f87171\" text-anchor=\"end\" font-weight=\"500\">air or O₂</text><text x=\"90\" y=\"131\" font-size=\"11\" fill=\"#f87171\" text-anchor=\"end\" font-weight=\"500\">+ heat</text><line x1=\"260.0\" y1=\"10.0\" x2=\"260.0\" y2=\"215.0\" stroke=\"#60a5fa\" stroke-width=\"2.6\" stroke-linecap=\"round\"/><polygon points=\"260.0,215.0 255.7,206.0 264.3,206.0\" fill=\"#60a5fa\"/><text x=\"270\" y=\"100\" font-size=\"13\" fill=\"#60a5fa\" text-anchor=\"start\" font-weight=\"700\">reduction</text><text x=\"270\" y=\"117\" font-size=\"11\" fill=\"#60a5fa\" text-anchor=\"start\" font-weight=\"500\">H₂ or CO</text><text x=\"270\" y=\"131\" font-size=\"11\" fill=\"#60a5fa\" text-anchor=\"start\" font-weight=\"500\">+ heat</text><text x=\"180\" y=\"244\" font-size=\"11\" fill=\"#94a3b8\" text-anchor=\"middle\" font-weight=\"500\">higher = more oxygen per iron atom</text></svg>","max_width":380},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"t":{"type":"Text","props":{"content":"Up adds oxygen: oxidation, by air or $\\ce{O2}$ with heat. Down removes oxygen: reduction, by $\\ce{H2}$ or CO."},"children":[]},"t2":{"type":"Text","props":{"content":"Then pick the exact condition. It decides the product."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["d","t","t2","m"]}}},"title":"Read each arrow: up or down?"},{"id":"s3","kind":"example","spec":{"root":"root","elements":{"e1":{"type":"Formula","props":{"latex":"\\ce{3Fe + 2O2 ->[\\Delta] Fe3O4}"},"children":[]},"e2":{"type":"Formula","props":{"latex":"\\ce{Fe3O4 + H2 ->[400-700\\,^{\\circ}C] 3FeO + H2O}"},"children":[]},"e3":{"type":"Formula","props":{"latex":"\\ce{4FeO + O2 ->[\\Delta] 2Fe2O3}"},"children":[]},"e4":{"type":"Formula","props":{"latex":"\\ce{Fe2O3 + 3CO ->[\\text{higher than }700\\,^{\\circ}C] 2Fe + 3CO2}"},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a","label":"air or steam, red hot"},{"to":"c","from":"b","label":"$\\ce{H2}$, 400–700 °C"},{"to":"d","from":"c","label":"hot air"},{"to":"a","from":"d","label":"CO, higher than 700 °C"}],"nodes":[{"id":"a","label":"Fe"},{"id":"b","label":"$\\ce{Fe3O4}$"},{"id":"c","label":"FeO"},{"id":"d","label":"$\\ce{Fe2O3}$"}],"layout":"cycle","caption":"Book Q6 (a)"},"children":[]},"r1":{"type":"Reveal","props":{"label":"1. Fe → Fe₃O₄"},"children":["e1","w1"]},"r2":{"type":"Reveal","props":{"label":"2. Fe₃O₄ → FeO"},"children":["e2","w2"]},"r3":{"type":"Reveal","props":{"label":"3. FeO → Fe₂O₃"},"children":["e3","w3"]},"r4":{"type":"Reveal","props":{"label":"4. Fe₂O₃ → Fe"},"children":["e4","w4"]},"w1":{"type":"Text","props":{"size":"sm","content":"Up: red hot iron in dry air or oxygen."},"children":[]},"w2":{"type":"Text","props":{"size":"sm","content":"Down, middle rung: hydrogen at 400–700 °C."},"children":[]},"w3":{"type":"Text","props":{"size":"sm","content":"Up: FeO is easily oxidized in hot air."},"children":[]},"w4":{"type":"Text","props":{"size":"sm","content":"Down all the way: the blast furnace equation."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fl","r1","r2","r3","r4"]}}},"title":"Worked: diagram (a)"},{"id":"s4","kind":"example","spec":{"root":"root","elements":{"f":{"type":"Formula","props":{"latex":"\\ce{Fe + H2SO4 ->[(dil)] FeSO4 + H2}","caption":"Arrow 1, done for you"},"children":[]},"m":{"type":"Misconception","props":{},"children":[]},"fl":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a","label":"dilute $\\ce{H2SO4}$"},{"to":"c","from":"b","label":"heat"},{"to":"d","from":"c","label":"CO, 230–300 °C"},{"to":"e","from":"d","label":"CO, higher than 700 °C"}],"nodes":[{"id":"a","label":"Fe"},{"id":"b","label":"$\\ce{FeSO4}$"},{"id":"c","label":"$\\ce{Fe2O3}$"},{"id":"d","label":"$\\ce{Fe3O4}$"},{"id":"e","label":"Fe"}],"caption":"Book Q6 (b), main path. It also has Fe₃O₄ → Fe₂O₃ and Fe₂O₃ → Fe."},"children":[]},"x1":{"type":"EquationBuilder","props":{"prompt":"Arrow 2: heat iron (II) sulphate.","answers":[2,1,1,1],"template":"\\ce{{?}FeSO4 ->[\\Delta] {?}Fe2O3 + {?}SO2 + {?}SO3}"},"children":[]},"x2":{"type":"EquationBuilder","props":{"prompt":"Arrow 3: the lowest rung.","answers":[3,1,2,1],"template":"\\ce{{?}Fe2O3 + {?}CO ->[230-300\\,^{\\circ}C] {?}Fe3O4 + {?}CO2}"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["fl","m","f","x1","x2"]}}},"title":"Faded: diagram (b)"},{"id":"s5","kind":"check","spec":{"root":"root","elements":{"c":{"type":"Classify","props":{"items":[{"id":"i1","text":"CO at 230–300 °C"},{"id":"i2","text":"$\\ce{H2}$ at 400–700 °C"},{"id":"i3","text":"CO higher than 700 °C"},{"id":"i4","text":"CO at 400–700 °C"}],"answer":{"fe":["i3"],"o1":["i2","i4"],"o4":["i1"]},"prompt":"$\\ce{Fe2O3}$ is reduced under each condition. Sort by the product.","categories":[{"id":"o4","label":"$\\ce{Fe3O4}$"},{"id":"o1","label":"FeO"},{"id":"fe","label":"Fe"}]},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["c"]}}},"title":"Which rung?"},{"id":"s6","kind":"check","spec":{"root":"root","elements":{"q":{"type":"MCQ","props":{"options":[{"id":"a","text":"CO, higher than 700 °C","correct":true},{"id":"b","text":"CO, 230–300 °C","correct":false},{"id":"c","text":"Hot air","correct":false},{"id":"d","text":"Dilute $\\ce{H2SO4}$","correct":false}],"question":"Which reagent and condition turn $\\ce{Fe3O4}$ into iron?"},"children":[]},"x":{"type":"EquationBuilder","props":{"prompt":"Diagram (b), $\\ce{Fe3O4}$ → $\\ce{Fe2O3}$: heat in air. Use whole numbers.","answers":[4,1,6],"template":"\\ce{{?}Fe3O4 + {?}O2 ->[\\Delta] {?}Fe2O3}"},"children":[]},"q2":{"type":"MCQ","props":{"options":[{"id":"a","text":"Heating in hot air","correct":true},{"id":"b","text":"Heating in absence of air","correct":false},{"id":"c","text":"CO at 230–300 °C","correct":false},{"id":"d","text":"Dilute $\\ce{H2SO4}$","correct":false}],"question":"Which condition turns FeO into $\\ce{Fe2O3}$?"},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["x","q","q2"]}}},"title":"Your turn: the last arrows"},{"id":"s7","kind":"recap","spec":{"root":"root","elements":{"b":{"type":"BulletList","props":{"items":["Up (more oxygen): air or $\\ce{O2}$ with heat.","Down (less oxygen): $\\ce{H2}$ or CO; the temperature decides how far.","$\\ce{Fe2O3}$ + CO: 230–300 °C → $\\ce{Fe3O4}$; 400–700 °C → FeO; higher than 700 °C → Fe.","Fe → $\\ce{FeSO4}$: dilute $\\ce{H2SO4}$. $\\ce{FeSO4}$ → $\\ce{Fe2O3}$: heat."]},"children":[]},"e":{"type":"Callout","props":{"variant":"exam"},"children":[]},"rv":{"type":"Reveal","props":{},"children":["rvt"]},"rvt":{"type":"Text","props":{"content":"The temperature decides how much oxygen CO removes. At 230–300 °C, CO turns $\\ce{Fe2O3}$ into $\\ce{Fe3O4}$; higher than 700 °C, it removes all the oxygen and gives iron."},"children":[]},"root":{"type":"Stack","props":{"gap":"lg"},"children":["b","e","self","rv"]},"self":{"type":"Text","props":{"content":"Can you explain why CO gives Fe₃O₄ in one case and iron in another?"},"children":[]}}},"title":"Summary"}],"title":"Iron and its oxides: reaction diagrams","minutes":9,"book_ref":"Ch.1 Evaluation Q6 (diagrams a and b), p.26; reactions pp.18, 21-24","subtitle":"Reagent and condition for every arrow","objectives":["Choose the reagent and condition for each arrow in a diagram of iron and its oxides.","Write the balanced equation for each step."],"concept_ids":["fe.conversions"]},"layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"You assumed the reactants alone decide the product. Let's check whether the arrows in diagrams agree."},{"id":"b","feedback":"Right. The condition is part of every arrow. Let's read arrows like an examiner."}],"explanation":"CO and $\\ce{Fe2O3}$ can give different products: the temperature decides. At 230–300 °C they give $\\ce{Fe3O4}$, and above 700 °C they give iron, so the condition over the arrow is part of the reaction."}},"s2":{"m":{"statement":"The condition over the arrow does not change the product.","correction":"It does: 'in absence of air' keeps FeO, while 'in hot air' oxidizes it to $\\ce{Fe2O3}$. Opposite results."}},"s4":{"m":{"statement":"The same reagent always gives the same product.","correction":"CO gives $\\ce{Fe3O4}$ at 230–300 °C, but iron above 700 °C. Hotter removes more oxygen."},"x1":{"explanation":"2 Fe for one Fe₂O₃; the 2 S leave as SO₂ and SO₃."},"x2":{"explanation":"6 Fe make 2 Fe₃O₄. 9 O − 8 O leaves 1 O for one CO."}},"s5":{"c":{"items":[{"id":"i1","feedback":"This is the coolest rung: it removes only a little oxygen."},{"id":"i2","feedback":"This is the middle rung: it removes more oxygen than the coolest rung, but not all of it."},{"id":"i3","feedback":"This is the hottest rung, as in the blast furnace: all the oxygen goes."},{"id":"i4","feedback":"Same gas as the coolest rung, but hotter: 400–700 °C is the middle rung."}],"explanation":"Same reagent, different temperature, different product."}},"s6":{"q":{"options":[{"id":"a","feedback":"Right. The top rung removes all the oxygen."},{"id":"b","feedback":"That is the coolest rung, and it does not remove all the oxygen."},{"id":"c","feedback":"Air adds oxygen, but $\\ce{Fe3O4}$ → Fe is a step down that removes oxygen."},{"id":"d","feedback":"An acid gives a salt, not the metal: it does not remove oxygen."}],"explanation":"CO at a temperature higher than 700 °C turns $\\ce{Fe3O4}$ into iron, because it removes all the oxygen. CO at 230–300 °C stops at $\\ce{Fe3O4}$, hot air adds oxygen, and a dilute acid gives a salt, not the metal."},"x":{"explanation":"The book writes $\\ce{2Fe3O4 + 1/2O2 -> 3Fe2O3}$. Doubled: 4, 1, 6."},"q2":{"options":[{"id":"a","feedback":"Right. FeO is easily oxidized in hot air."},{"id":"b","feedback":"In absence of air, nothing supplies the extra oxygen that FeO needs to become Fe₂O₃."},{"id":"c","feedback":"CO removes oxygen, but FeO → Fe₂O₃ adds oxygen."},{"id":"d","feedback":"An acid gives a salt and water; it does not add oxygen."}],"explanation":"Heating in hot air turns FeO into $\\ce{Fe2O3}$: FeO is easily oxidized in hot air, $\\ce{4FeO + O2 -> 2Fe2O3}$. This step adds oxygen, so it needs air, not a reducing agent like CO."}},"s7":{"e":{"body":"Diagram questions (Q6): write each equation with its condition over the arrow."}}}},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"steps":{"s1":{"q":{"options":[{"id":"a","feedback":"إنت افترضت إن المواد المتفاعلة لوحدها هي اللي بتحدد الناتج. يلا نشوف الأسهم اللي في المخططات بتقول كده ولا لأ."},{"id":"b","feedback":"صح. الظرف جزء من كل سهم. يلا نقرا الأسهم بعين المصحّح."}],"explanation":"الـ CO والـ $\\ce{Fe2O3}$ ممكن يدّوا نواتج مختلفة، ودرجة الحرارة هي اللي بتحدد: عند 230–300 °C بيدّوا $\\ce{Fe3O4}$، وعند أعلى من 700 °C بيدّوا iron، يعني الظرف اللي فوق السهم جزء من الـ reaction."}},"s2":{"m":{"statement":"الظرف اللي مكتوب فوق السهم مش بيغيّر الناتج.","correction":"لأ، بيغيّره: 'in absence of air' الـ FeO بيفضل زي ما هو، لكن 'in hot air' بيحصله oxidation ويبقى $\\ce{Fe2O3}$. نتيجتين عكس بعض."}},"s4":{"m":{"statement":"نفس المادة دايمًا بتدّي نفس الناتج.","correction":"الـ CO بيدّي $\\ce{Fe3O4}$ عند 230–300 °C، لكن بيدّي iron عند أعلى من 700 °C. كل ما الحرارة تعلى، بيتشال oxygen أكتر."},"x1":{"explanation":"2 Fe عشان Fe₂O₃ واحد؛ والـ 2 S بيخرجوا في صورة SO₂ ومعاه SO₃."},"x2":{"explanation":"6 Fe بيعملوا 2 Fe₃O₄. والـ 9 O ناقص 8 O يفضل 1 O، يكفي CO واحد."}},"s5":{"c":{"items":[{"id":"i1","feedback":"دي أبرد درجة، وبتشيل جزء صغير من الـ oxygen، مش كله."},{"id":"i2","feedback":"دي الدرجة اللي في النص (400–700 °C): بتشيل oxygen أكتر من أبرد درجة، لكن مش كله."},{"id":"i3","feedback":"دي أسخن درجة، زي الـ blast furnace، والـ oxygen كله بيمشي فيها."},{"id":"i4","feedback":"نفس الغاز بتاع أبرد درجة لكن أسخن: الـ 400–700 °C هي الدرجة اللي في النص، مش أبرد درجة."}],"explanation":"نفس المادة، حرارة مختلفة، ناتج مختلف."}},"s6":{"q":{"options":[{"id":"a","feedback":"صح. الدرجة اللي فوق خالص بتشيل الـ oxygen كله."},{"id":"b","feedback":"دي أبرد درجة، ومش بتشيل الـ oxygen كله."},{"id":"c","feedback":"الهوا بيضيف oxygen، والـ $\\ce{Fe3O4}$ → Fe محتاج oxygen يتشال."},{"id":"d","feedback":"الـ acid بيدي salt، مش الـ metal."}],"explanation":"الـ CO عند أعلى من 700 °C هو اللي بيحوّل الـ $\\ce{Fe3O4}$ لـ iron، عشان بيشيل الـ oxygen كله. الـ CO عند 230–300 °C بيوقف عند الـ $\\ce{Fe3O4}$، والهوا السخن بيضيف oxygen، والـ dilute acid بيدي salt مش الـ metal."},"x":{"explanation":"الكتاب كاتبها $\\ce{2Fe3O4 + 1/2O2 -> 3Fe2O3}$. ولو ضربناها في 2: 4، 1، 6."},"q2":{"options":[{"id":"a","feedback":"صح. الـ FeO بيحصله oxidation بسهولة في الهوا السخن."},{"id":"b","feedback":"التسخين في غياب الهوا مفيهوش مصدر للـ oxygen الزيادة اللي التحويل ده محتاجه."},{"id":"c","feedback":"الـ CO بيشيل oxygen، والـ FeO → Fe₂O₃ بيضيف oxygen."},{"id":"d","feedback":"الـ acid بيدي salt ومية، ومش بيضيف oxygen للـ FeO."}],"explanation":"التسخين في الهوا السخن هو اللي بيحوّل الـ FeO لـ $\\ce{Fe2O3}$: الـ FeO بيحصله oxidation بسهولة في الهوا السخن، $\\ce{4FeO + O2 -> 2Fe2O3}$. الخطوة دي بتضيف oxygen، فمحتاجة هوا، مش reducing agent زي الـ CO."}},"s7":{"e":{"body":"أسئلة المخططات 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FRAME 0 (t=0, not on a cue): full-bleed night Cairo + steel truss bridge (custom silhouette: deck, girders, cable arcs in steel #A7B3C4, river reflection), car-light streaks (YK.particles mode 'float', seed 1, alpha .35, flattened horizontal), YK.camera slow push 1.0 → 1.12 on the centre girder. In-world plate on the girder fades in on 'steel': 'Steel bridge · Cairo' (Cairo 800, 40).","speaker":"الراوي","tts_text":"القاهرة بالليل… كوبري steel شايل آلاف العربيات، ومحدش واخد باله منه.","screen_text":"Steel bridge · Cairo"},{"id":"c2","visual":"BIG MOVE of the cold open: YK.zoomThrough({from: drawBridge, to: drawLattice, focus: girder, zoom:12, badge:'×10^9'}) driven over 1.2 s from cue 'مليارات'; keep p = 1 + badge 1.5 s, then badgeOut. 'to' scene: hex lattice of Fe discs (YK.lattice pack:'hex', rows 5, cols 9, color atomFe #E0703A). On 'وواحدة' the centre disc brightens (YK.glowCircle gold) and the rest dim to 50%.","speaker":"الراوي","tts_text":"جوه الـ steel ده مليارات ذرات حديد… وواحدة منهم عندها حكاية.","screen_text":"×10⁹"},{"id":"c3","visual":"Camera pushes onto the bright disc → it becomes YK.character({el:'Fe', speaker:'فيرّو', tag:'Ferro', r:170, t}) at (600, 520), lattice blurred behind. Speaking glow + 1.04 scale (rig). On 'صخرة' a memory inset on the right stage: YK.ore(ctx, 1360, 520, 170, {type:'hematite', label:false}) in a soft vignette, fades out at line end.","speaker":"فيرّو","tts_text":"إنتو فاكرين الحديد ده عادي؟ أنا كنت صخرة حمرا في الصحرا.","screen_text":"Ferro"},{"id":"c4","visual":"Ferro mood 'proud'. On 'الأربعة' four gold sparks (YK.dot gold, glow 1) circle inside the disc rim, one per 0.15 s (YK.stagger). No text besides the tag.","speaker":"فيرّو","tts_text":"أنا فيرّو، ذرة حديد… وسري كله في الأربعة اللي لوحدهم جوايا.","screen_text":"Ferro · Fe"},{"id":"c5","visual":"Ferro's HUD appears under the tag on 'three' (character hud:{} → YK.configStrip Fe, [Ar] 4s² 3d⁶, size ≥ 72 so the label is ≥ 32 px); on 'unpaired' hud.unpaired 0 → 1: the 4 unpaired 3d arrows glow gold + tag 'unpaired = 4'. The gold sparks fly into those 4 boxes.","speaker":"الراوي","tts_text":"أربع electrons unpaired في الـ three d بتاعته… دول أبطال الحكاية الحقيقيين.","screen_text":"4 unpaired 3d electrons"},{"id":"c6","visual":"Text panel left (x 96–740): the big question in Cairo 1000 64, 'unpaired' in gold, on line start; Ferro stays right (x 1300). After the line (pause): YK.titleCard({title:'The Lonely Four', subtitle:'Part 1 of 2'}) ≤ 2.5 s over a slow fade to black.","speaker":"الراوي","tts_text":"والسؤال: إزاي أربع electrons unpaired يدّوا الحديد شخصيته كلها؟","screen_text":"How do 4 unpaired electrons shape iron?","pause_after_s":2},{"id":"a1l1","visual":"[ACT 1 · SCENE 1a · te.position-in-periodic-table · new: transition elements, inner transition elements] YK.actCard({num:1, title:'The District in the Middle', size:100}) at line start, ≤ 2.5 s, then ESTABLISHING WIDE: YK.dBlockZoom p:0 (full table) styled as a night city (cells = lit windows, faint glow), camera drift (YK.camera 1.0 → 1.05). Grade act1. Book p.3.","speaker":"الراوي","tts_text":"الحكاية بتبدأ في مدينة غريبة اسمها الـ periodic table… وفيرّو ساكن فيها.","screen_text":"ACT 1 · The District in the Middle"},{"id":"a1l2","visual":"s-block columns glow pink on 's-block', p-block cyan on 'p-block' (left → right), label pills 's-block' / 'p-block' above them (YK.tag 40); on 'النص' the middle district lights violet, the rest dims to 40%.","speaker":"الراوي","tts_text":"الـ s-block على الشمال، والـ p-block على اليمين… والحي اللي في النص ده بتاعنا.","screen_text":"s-block · p-block"},{"id":"a1l3","visual":"d- and f-block cells pulse violet; YK.counter 0 → 60 with suffix '+' (YK.label, JetBrains Mono digits) next to a pill 'Transition elements' on 'ستين'. Book p.3 ('more than 60 elements').","speaker":"الراوي","tts_text":"ده حي الـ transition elements: أكتر من ستين عنصر، يعني أكتر من نص العناصر.","screen_text":"Transition elements: more than 60 elements"},{"id":"a1l4","visual":"dBlockZoom kinds 0 → 1 on 'main': only the book label 'Main transition elements' over the d-block for now (draw the inner label yourself on a1l5 — kit 'kinds' draws both together, so use labels:{inner:''} here). Book p.3.","speaker":"الراوي","tts_text":"والحي ده نوعين: الأول main transition elements، في النص بالظبط.","screen_text":"Main transition elements"},{"id":"a1l5","visual":"Label 'Inner transition elements' over the two f rows on 'inner'; on 'مش' the f rows dim to 25% with a small tag 'not studied here'. Book p.3 ('we'll study the main transition elements only').","speaker":"الراوي","tts_text":"والتاني inner transition elements، في الصفين اللي تحت… ودول مش موضوعنا.","screen_text":"Inner transition elements (not studied here)"},{"id":"a1l6","visual":"[SCENE 1b · te.d-block-groups · new: d-block] Camera push into the d-block; the 10 columns light one by one left → right (YK.stagger gap .08) from 'عشر'; small column numbers 3…12 above them (≥ 32 px). f rows fade out.","speaker":"الراوي","tts_text":"الـ main transition elements هما الـ d-block: عشر columns جنب بعض.","screen_text":"d-block: 10 vertical columns"},{"id":"a1l7","visual":"Text panel left: a row of 5 empty orbital boxes labelled 'd sublevel' (YK.electronBoxes boxes:5, label 'd') fills to 10 electrons (fill 0 → 1 over the line) with '10' tag; the 10 columns on the right pulse in sync, one per electron.","speaker":"الراوي","tts_text":"عشر بالظبط، عشان الـ d-sublevel بياخد لحد عشرة electrons مش أكتر.","screen_text":"d sublevel: up to 10 electrons"},{"id":"a1l8","visual":"dBlockZoom groups 0 → 1 on 'group' (book labels IIIB…IIB over the columns; VIII spans 3 columns, gold bracket YK.bracket); on 'فيرّو' the Fe cell glows gold and a tiny Ferro disc (r 40, tag:false) pops on it. Book p.3.","speaker":"الراوي","tts_text":"والـ group eight لوحده واخد تلات columns… وفيرّو ساكن في أولهم.","screen_text":"Group VIII: 3 columns (Fe · Co · Ni)"},{"id":"a1l9","visual":"[SCENE 1c · te.transition-series, te.first-series-elements · new: transition series] dBlockZoom series 0 → 1: brackets on periods 4–7 of the d-block styled as four lit streets; in-world street signs at their left ends (YK.tag): '3d Street', '4d Street', '5d Street', '6d Street', appearing top → bottom from 'أربع'. Book pp.4–5.","speaker":"الراوي","tts_text":"والحي فيه أربع شوارع، كل شارع transition series بيملا d-sublevel مختلف.","screen_text":"4 transition series: 3d · 4d · 5d · 6d"},{"id":"a1l10","visual":"The '3d Street' row lights gold, others dim; label pill 'First transition series' on 'first'; 'period 4' tag at the row's left on 'period'.","speaker":"الراوي","tts_text":"شارع فيرّو هو الـ first transition series، بيملا three d في period أربعة.","screen_text":"First transition series: 3d · period 4"},{"id":"a1l11","visual":"dBlockZoom p 0 → 1 (zoom/morph into the first-series strip Sc → Zn, 1 row, stripY 600) from 'عشر'; names 0 → 1 (book English names under the tiles); Sc tile flashes on 'scandium', Zn on 'zinc'. Book p.5.","speaker":"الراوي","tts_text":"عشر جيران في الشارع، من الـ scandium في الأول لحد الـ zinc في الآخر.","screen_text":"Sc → Zn"},{"id":"a1l12","visual":"Over the Cr tile a chrome sheen sweeps left → right (YK.marker) + tag 'Metal plating' on 'plating'; over the Zn tile a grey coat wraps a small Fe bar + tag 'Galvanizing' on 'zinc'. Tags ≥ 32 px, below the strip. Book pp.6, 8.","speaker":"الراوي","tts_text":"كل جار ليه شغلانة: الـ chromium للـ plating، والـ zinc بيحمي الحديد من الصدا.","screen_text":"Cr: metal plating · Zn: galvanizing"},{"id":"a1l13","visual":"[SCENE 1d · te.electron-configuration · new: — (Hund's rule = prereq chip)] MEDIUM: Ferro (YK.character Fe, tag 'Ferro', r 170) at (520, 560) slides in from the Fe tile; right stage YK.elementCard({sym:'Fe', w:420, config:''}) pops on 'بطاقتي' (ID card), Z = 26 visible.","speaker":"فيرّو","tts_text":"ودي بطاقتي الشخصية… بصّوا على العنوان بتاعي كويس.","screen_text":"₂₆Fe"},{"id":"a1l14","visual":"Ferro's HUD builds live (hud:{step}): [Ar] core chip on 'argon', 4s² on 'four', then the six 3d electrons arrive on 'three' (step 2 → 8 over 1.8 s). Live label '[Ar] 4s^2 3d^6' (book order). The element card shows the same config line on 'ستة'. Book p.8 table.","speaker":"الراوي","tts_text":"الأول الـ argon core، والـ four s فيها اتنين، والـ three d ستة.","screen_text":"₂₆Fe: [Ar] 4s² 3d⁶"},{"id":"a1l15","visual":"YK.prereqChip(ctx, t, \"Hund's rule\") top-left from line start, ≤ 8 s. Replay the 3d build slower on Ferro's HUD: five ↑ land one per box first, the 6th ↓ pairs in box 1 on 'pairing' (flash on that box).","speaker":"الراوي","tts_text":"والـ three d بتتملي حسب Hund's rule: واحد في كل orbital، والـ pairing بعدها.","screen_text":"Hund's rule: one electron in each orbital first, then pairing"},{"id":"a1l16","visual":"TWO-SHOT: Mana enters right — YK.character({el:'Mn', speaker:'مانا', tag:'Mana', r:170, hud:{}}) at (1400, 560); Ferro left at (520, 560) dims to 80% (rig). On 'خمسة' her five ↑ glow (hud.unpaired 0 → 1). Book p.8 point 1 (singly till Mn).","speaker":"مانا","tts_text":"وأنا الـ manganese، جارته… عندي خمسة بالظبط، كل orbital فيه واحد.","screen_text":"Mana · ₂₅Mn: [Ar] 4s² 3d⁵"},{"id":"a1l17","visual":"Ferro speaks (glow). His HUD: the paired box 1 flashes on 'السادس', then the 4 single arrows pulse (no 'unpaired' label yet: the term lands on the next line, voiced). Mana dims.","speaker":"فيرّو","tts_text":"وأنا السادس عندي دخل على أول واحد… فاضل أربعة لوحدهم.","screen_text":"Fe: 3d⁶"},{"id":"a1l18","visual":"HUD tag 'unpaired = 4' + gold glow on 'unpaired'; then a brief title sting: 'The Lonely Four' (Cairo 1000 72, gold) slides in above Ferro on 'اسم', with '= 4 unpaired electrons' under it (Cairo 800 40), out at line end.","speaker":"الراوي","tts_text":"أربعة unpaired… ودول الأربعة اللي في اسم الفيلم.","screen_text":"unpaired = 4 · The Lonely Four"},{"id":"a1l19","visual":"[SCENE 1e · te.cr-cu-anomaly · new: half-filled · ◆ predict 1 · ✕ Cr 4s² 3d⁴] Ferro and Mana shrink to the left edge (r 110, two-shot keeps both visible). Stage: YK.configStrip({el:'Cr', size:110, anomaly:0, step:…}) at (1300, 560) builds the EXPECTED 4s² 3d⁴ from 'المتوقع'; its label shows '[Ar] 4s^2 3d^4 ?' (gold '?'). Book pp.8–9.","speaker":"الراوي","tts_text":"طب جارهم الـ chromium؟ المتوقع four s اتنين، و three d أربعة.","screen_text":"₂₄Cr: [Ar] 4s² 3d⁴ ?"},{"id":"a1l20","visual":"PREDICT ◆1. Question card in the text panel ('₂₄Cr: real configuration?'), YK.thinkRing (load lib/short.js in page.html) at (1300, 820) from cue 'فكّروا' to the next line's start (3 s pause). Ferro glows while speaking, then idle.","speaker":"فيرّو","tts_text":"بس الـ chromium مش كده خالص… تفتكروا هو عامل إزاي؟ فكّروا.","screen_text":"Cr: what is the real configuration?","pause_after_s":3},{"id":"a1l21","visual":"REVEAL: Cr strip anomaly 0 → 1 on 'بيكسر' (the 2nd 4s electron hops into 3d). The expected label shrinks to 60%, turns coral and gets YK.wrongMark for ≤ 1 s, then fades; new label '[Ar] 4s^1 3d^5' in mint with YK.rightMark.","speaker":"الراوي","tts_text":"الـ chromium بيكسر التوقع: four s واحد، والـ three d خمسة.","screen_text":"₂₄Cr: [Ar] 4s¹ 3d⁵"},{"id":"a1l22","visual":"Gold brackets over the 4s box and the 3d boxes on 'half-filled' with tag 'half-filled'; the strip's mint 'stable' badge (auto with anomaly) on 'stability'.","speaker":"الراوي","tts_text":"الاتنين بقوا half-filled، وده بيدّي extra stability للـ atom كله.","screen_text":"4s¹ and 3d⁵: half-filled → extra stability"},{"id":"a1l23","visual":"Mana grows back to r 170 on the right (mood proud), her HUD 3d⁵ gets the same gold bracket + 'half-filled' tag on 'half-filled'; Ferro dims.","speaker":"مانا","tts_text":"شايفين؟ الـ half-filled ده ستايلي أنا كمان.","screen_text":"Mn: 3d⁵ (half-filled)"},{"id":"a1l24","visual":"Second strip under the Cr one: YK.configStrip({el:'Cu', size:110, anomaly: prog from 'copper'}) at (1300, 860): expected 4s² 3d⁹ → 4s¹ 3d¹⁰ (the hop on 'واحد'); tag 'filled' over 3d on 'filled'. Book p.9.","speaker":"الراوي","tts_text":"والـ copper برضه: الـ four s واحد، والـ three d بقت filled بعشرة.","screen_text":"₂₉Cu: [Ar] 4s¹ 3d¹⁰ (3d filled)","pause_after_s":2},{"id":"a2l1","visual":"[ACT 2 · SCENE 2a · te.ion-configuration · new: oxidation state · ✕ 3d leaves first] YK.actCard({num:2, title:'Who Gives Up an Electron?', size:100}) ≤ 2.5 s, then ESTABLISHING WIDE: the first-series street at dusk (strip tiles as house fronts, YK.dBlockZoom p:1, names:1), Ferro (left) and Mana (right) walk in at r 150 with HUDs. Grade act2.","speaker":"الراوي","tts_text":"في الشارع ده، الذرات بتدّي electrons بسهولة… بس مين بيطلع الأول؟","screen_text":"ACT 2 · Who Gives Up an Electron?"},{"id":"a2l2","visual":"TWO-SHOT medium: Ferro (520, 540, r 170, HUD Fe) speaks; Mana (1400, 540) dims. Two of his electrons jitter (anticipation, shiver mood, small).","speaker":"فيرّو","tts_text":"أنا هخسر اتنين دلوقتي… وإنتو شوفوا مين اللي هيمشي الأول.","screen_text":"Fe → Fe²⁺"},{"id":"a2l3","visual":"MISCONCEPTION (said once): a coral STATIC YK.electronBoxes ghost (Fe²⁺ as 4s² 3d⁴; never animate configStrip for it) at 70% size in the centre top (y 260), smaller than Ferro's HUD; YK.wrongMark on it at line end. Mana speaks (glow).","speaker":"مانا","tts_text":"ناس كتير فاكرة إن آخر اتنين دخلوا الـ three d هما اللي هيطلعوا.","screen_text":"✕ Fe²⁺ = [Ar] 4s² 3d⁴"},{"id":"a2l4","visual":"Ghost fades on 'غلط'. Ferro's HUD charge:2, remove 0 → 1 from 'بيطلعوا' (the two 4s electrons fly off up-right with cyan trails). Tag 'outer level' over the 4s box on 'outer'. G43: never 'lower in energy'. Book p.9 point 3.","speaker":"الراوي","tts_text":"غلط: الـ four s هي الـ outer level، فالاتنين بتوعها بيطلعوا الأول.","screen_text":"4s: the outer level → its electrons leave first"},{"id":"a2l5","visual":"HUD label switches to 'Fe^2+  [Ar] 3d^6' on 'خسرت'; charge badge '2+' on the disc; the 4 unpaired 3d arrows glow gold on 'الأربعة'. Ferro mood proud.","speaker":"فيرّو","tts_text":"خسرت اتنين، وأنا لسه زي ما أنا… الأربعة لسه معايا!","screen_text":"Fe²⁺: [Ar] 3d⁶ · unpaired = 4"},{"id":"a2l6","visual":"Term label 'oxidation state +2' (gold key) appears next to the charge badge on 'oxidation'; badge pulses.","speaker":"الراوي","tts_text":"ده الـ iron two، وزائد اتنين دي اسمها الـ oxidation state بتاعه.","screen_text":"Fe²⁺ · oxidation state +2"},{"id":"a2l7","visual":"[SCENE 2b · te.oxidation-states-trend · new: — · ✕ Fe +8] CUT to the stage chart: YK.oxStates(ctx, 820, 160, 1000, 760, {title:'Oxidation states'}) with ONLY the +2 dots shown (data copy with ox filtered to [2]; Sc column empty) appearing Ti → Zn on 'الجيران'; tag 'except Sc' under the empty Sc column on 'scandium'. Characters small at the left edge. Book p.9 point 3, table p.8.","speaker":"الراوي","tts_text":"كل الجيران عندهم زائد اتنين، ما عدا الـ scandium لوحده.","screen_text":"All show +2, except Sc"},{"id":"a2l8","visual":"Full book data for Sc → Mn only (later columns ox:[] — oxStates staggers all columns otherwise), gold max line grows Sc → Mn from 'بتطلع'; Mn column highlight on 'مانا'; Mana's disc at the edge glows.","speaker":"الراوي","tts_text":"وأعلى oxidation state بتطلع من الـ scandium لحد مانا، عند زائد سبعة.","screen_text":"Highest oxidation state rises: Sc → Mn (+7)"},{"id":"a2l9","visual":"Fe → Zn columns grow on 'وبعدي' (second YK.oxStates call), gold max line falls to +2 at Zn on 'بتنزل'. Mana speaks (glow).","speaker":"مانا","tts_text":"سبعة ده الرقم القياسي بتاعي… وبعدي الأرقام بتنزل لحد زائد اتنين.","screen_text":"Then it falls to +2 (Zn)"},{"id":"a2l10","visual":"A coral ghost dot '+8 ?' (YK.label, coral, 70% size) pops above the Fe column using py(8) on 'تمانية'. Ferro speaks, mood proud.","speaker":"فيرّو","tts_text":"وأنا بقى؟ أنا ممكن أخسر التمانية كلهم، وأبقى زائد تمانية!","screen_text":"Fe: +8 ?"},{"id":"a2l11","visual":"YK.wrongMark on the '+8' ghost on 'لأ' (≤ 1 s, then it fades); the Fe column's +2 and +3 dots pulse gold on 'اتنين' / 'وتلاتة', +6 stays dim. Book p.20 (states above +3 not important).","speaker":"الراوي","tts_text":"لأ يا فيرّو: الحديد مبيوصلش لزائد تمانية، والمهمين عنده اتنين وتلاتة بس.","screen_text":"✕ +8 · Fe: important states +2 and +3"},{"id":"a2l12","visual":"[SCENE 2c · te.multiple-oxidation-states · new: ionization potential] CUT: YK.stairs(ctx, 840, 200, 960, 700, {title:'Ionization potentials of vanadium', step:0}) appears on 'vanadium' as an in-world staircase; a small V disc (YK.atomDisc el:'V') stands on the bottom tread. Question in the text panel.","speaker":"الراوي","tts_text":"طب ليه عندهم oxidation states كتير كده؟ الـ vanadium هيورّينا السلم بتاعه.","screen_text":"Why several oxidation states?"},{"id":"a2l13","visual":"stairs step 0 → 1 on 'electron' (V → V⁺, 648; one electron leaves); term label 'ionization potential' (gold) in the text panel on 'ionization'.","speaker":"الراوي","tts_text":"الطاقة اللي بتشيل كل electron اسمها ionization potential، وبتزيد بالتدريج.","screen_text":"Ionization potential (kJ/mol)"},{"id":"a2l14","visual":"stairs step 1 → 5 from 'ستمية' to 'آلاف' (each tread shows its value once ≥ 60% up, kit rule); on 'قفزة' a gold bracket along the tread edges with tag 'gradual'. Book p.10 flowchart.","speaker":"الراوي","tts_text":"من ستمية تمانية وأربعين، لحد ستة آلاف خمسمية تلاتة وعشرين… من غير قفزة كبيرة.","screen_text":"648 → 1346 → 2858 → 4643 → 6523 kJ/mol: gradual"},{"id":"a2l15","visual":"Text panel: two short level bars labelled '4s' and '3d' drawn close together, bracket 'close in energy' on 'قريبين'; then the line 'several oxidation states' under them. Never draw 4s below 3d (G43).","speaker":"الراوي","tts_text":"عشان الـ four s والـ three d قريبين من بعض في الطاقة.","screen_text":"4s and 3d: close in energy → several oxidation states","pause_after_s":1},{"id":"a2l16","visual":"[SCENE 2d · te.definition, te.definition-applied · new: transition element (definition) · ◆ predict 2 (Cu)] WIDE: back on the street; Ferro walks along the tiles (left → right); Zinc (YK.atomDisc el:'Zn', silent; name tag 'Zinc' only its first 2 s in this act) leans at the last tile, unbothered.","speaker":"فيرّو","tts_text":"بس مش كل اللي ساكن في الشارع ده… يبقى واحد مننا رسمي.","screen_text":"Who is a transition element?"},{"id":"a2l17","visual":"Text panel: YK.termCard({term:'Transition element', def:'The element in which the orbitals of d or f contain electrons but they are not complete in their atomic state or in one of their oxidation states.', keys:['not complete']}) builds on 'transition'. Book p.10.","speaker":"الراوي","tts_text":"الـ transition element: عنصر الـ d-orbitals بتوعه فيها electrons، بس مش كاملة.","screen_text":"Transition element"},{"id":"a2l18","visual":"termCard keys 'atomic state' and 'oxidation states' highlight gold on 'atom' / 'oxidation' (YK.marker sweep).","speaker":"الراوي","tts_text":"مش كاملة في الـ atom نفسه… أو في oxidation state من بتوعه.","screen_text":"atomic state · one of their oxidation states"},{"id":"a2l19","visual":"Stage: Sc tile with YK.configStrip({el:'Sc', size:100}) at (1300, 480): 3d¹ glows on 'واحد'; YK.rightMark on 'أكيد'.","speaker":"الراوي","tts_text":"الـ scandium مثلاً: الـ three d فيها واحد بس… يبقى transition element أكيد.","screen_text":"Sc: 3d¹ → transition element ✓"},{"id":"a2l20","visual":"PREDICT ◆2. Stage: YK.configStrip({el:'Cu', size:100}) at (1300, 760), 3d¹⁰ all paired; question in the text panel; YK.thinkRing from 'فكّروا' to the next line start.","speaker":"الراوي","tts_text":"والـ copper؟ الـ three d عنده عشرة كاملة… transition ولا لأ؟ فكّروا.","screen_text":"Cu atom: 3d¹⁰. Transition element?","pause_after_s":3},{"id":"a2l21","visual":"Cu strip charge:2, remove 0 → 1 from 'يخسر' (4s¹ leaves first, then one 3d electron); label 'Cu^2+ [Ar] 3d^9' on 'تسعة'; YK.rightMark. Book p.10 Exercise 1.","speaker":"الراوي","tts_text":"أيوه: الـ copper لما يخسر اتنين، الـ three d بتبقى تسعة، مش كاملة.","screen_text":"Cu²⁺: 3d⁹ → transition element ✓"},{"id":"a2l22","visual":"Zinc disc with YK.configStrip({el:'Zn'}) → then charge:2 remove 0 → 1 on 'ion': 3d stays 10 (all boxes full both times). Book p.11 Exercise 2.","speaker":"الراوي","tts_text":"والـ zinc الـ three d عنده عشرة، في الـ atom وفي الـ ion كمان.","screen_text":"Zn and Zn²⁺: 3d¹⁰"},{"id":"a2l23","visual":"YK.wrongMark on the Zn tile on 'مش'; Zinc glides off the street to the right, slow and unbothered (no mood), on 'وبيسيب'.","speaker":"الراوي","tts_text":"فالـ zinc مش transition element… وبيسيب الشارع بهدوء.","screen_text":"Zn: not a transition element ✕","pause_after_s":1},{"id":"a2l24","visual":"[SCENE 2e · te.fe2-fe3-mn2-stability · new: — · ◆ predict 3 (Mn²⁺)] TWO-SHOT: Ferro left (HUD Fe²⁺), Mana right (HUD Mn²⁺ = charge 2 already removed: [Ar] 3d⁵). On 'أخسر' Ferro's HUD goes charge 3 with remove = lerp(2/3, 1, p) (only the 3rd electron moves: the paired 3d one flies off).","speaker":"فيرّو","tts_text":"أما أنا، ممكن أخسر واحد كمان… وأبقى مرتاح أكتر.","screen_text":"Fe²⁺ → Fe³⁺"},{"id":"a2l25","visual":"HUD label 'Fe^3+  [Ar] 3d^5' on 'خمسة'; mint 'stable' badge + 'half-filled' bracket on 'half-filled'. Book p.9 worked exercise.","speaker":"الراوي","tts_text":"بعد التالت، الـ three d بقت خمسة: half-filled، وده more stable بكتير.","screen_text":"Fe³⁺: [Ar] 3d⁵ half-filled → more stable"},{"id":"a2l26","visual":"Ferro leans toward Mana (small move right, mood proud); Mana's HUD label pulses 'Mn^2+ [Ar] 3d^5'.","speaker":"فيرّو","tts_text":"مانا! تعالي اعمليها زيي… اخسري واحد كمان وارتاحي!","screen_text":"Mana: Mn²⁺ [Ar] 3d⁵"},{"id":"a2l27","visual":"PREDICT ◆3. Text panel question 'Mn²⁺ → Mn³⁺ ?' (dashed arrow); YK.thinkRing between the two characters from 'فكّروا'. Both characters idle, no glow (narrator).","speaker":"الراوي","tts_text":"مانا دلوقتي manganese two… هتخسر واحد كمان زي فيرّو؟ فكّروا.","screen_text":"Will Mn²⁺ lose one more electron?","pause_after_s":3},{"id":"a2l28","visual":"Mana speaks, mood proud; her HUD gets the mint 'stable' badge + 'half-filled' bracket on 'half-filled'; the dashed arrow 'Mn²⁺ → Mn³⁺' gets YK.wrongMark.","speaker":"مانا","tts_text":"لأ شكراً. الـ three d بتاعتي خمسة، half-filled… وأنا مرتاحة كده.","screen_text":"Mn²⁺: 3d⁵ half-filled → not readily oxidized"},{"id":"a2l29","visual":"Text panel two rows, left-aligned: 'Fe²⁺ → Fe³⁺ ✓ easily oxidized' (on 'iron') and 'Mn²⁺ → Mn³⁺ ✕ not readily oxidized' (on 'manganese'). Book p.9.","speaker":"الراوي","tts_text":"عشان كده الـ iron two بيحصله oxidation بسهولة، والـ manganese two لأ.","screen_text":"Fe²⁺: easily oxidized · Mn²⁺: not readily oxidized","pause_after_s":2},{"id":"a3l1","visual":"[ACT 3 · SCENE 3a · te.magnetic-properties · new: paramagnetic, diamagnetic · ◆ predict 4 (Zn)] YK.actCard({num:3, title:'Magnetic Personality', size:100}) ≤ 2.5 s, then ESTABLISHING WIDE: a dark lab; a big horseshoe YK.magnet({type:'horseshoe', size:520, angle:-Math.PI/2, field: prog}) on the right stage, field lines flowing; Ferro left (r 150). Grade act3.","speaker":"الراوي","tts_text":"فيرّو عنده هواية غريبة… أي magnet بيشده ناحيته على طول.","screen_text":"ACT 3 · Magnetic Personality"},{"id":"a3l2","visual":"Ferro drifts toward the magnet (+140 px over the line, ease out) — back to his neutral HUD [Ar] 4s² 3d⁶ (this act uses the atom); 4 unpaired arrows glow gold on 'الأربعة'.","speaker":"فيرّو","tts_text":"مش ذنبي إني جذاب… دي الأربعة اللي جوايا.","screen_text":"Fe: 4 unpaired electrons"},{"id":"a3l3","visual":"CLOSE-UP on the HUD: each unpaired arrow emits a small dashed cyan field loop on 'magnetic' (1st), the loops align with the magnet's lines on 'الخارجي'. Book p.13.","speaker":"الراوي","tts_text":"الـ electrons الـ unpaired بتعمل magnetic field صغير، فبتتشد للـ magnetic field الخارجي.","screen_text":"Unpaired electrons → attracted to an external magnetic field"},{"id":"a3l4","visual":"Ferro snaps closer to the pole; term label 'Paramagnetic' (Cairo 1000 56, gold) in the text panel on 'paramagnetic' (1st).","speaker":"الراوي","tts_text":"والمادة اللي بتتشد كده اسمها paramagnetic، وفيرّو paramagnetic من الدرجة الأولى.","screen_text":"Paramagnetic"},{"id":"a3l5","visual":"PREDICT ◆4. Zinc (atomDisc Zn, tag 'Zinc' ≤ 2 s, first appearance in this act) slides in under the magnet's left side, HUD-like box row 3d¹⁰ all ↑↓; question in the text panel; YK.thinkRing from 'فكّروا'.","speaker":"الراوي","tts_text":"طب الـ zinc، كل الـ electrons بتوعه paired… الـ magnet هيشده؟ فكّروا.","screen_text":"Zn: all electrons paired. Attracted?","pause_after_s":3},{"id":"a3l6","visual":"Zinc is nudged slightly AWAY from the magnet (−60 px, ease out) on 'بيتنفر'; label 'Diamagnetic' on 'diamagnetic'. Not 'ignored': the book says repelled. Book p.14.","speaker":"الراوي","tts_text":"لأ: الـ zinc diamagnetic، بيتنفر من الـ magnetic field شوية.","screen_text":"Zn: diamagnetic → repelled"},{"id":"a3l7","visual":"[SCENE 3b · te.magnetic-moment-from-config · new: magnetic moment · ✕ count in the atom] Text panel: term label 'Magnetic moment' on 'magnetic'; one YK.momentMeter (r 150) appears on the stage, needle sweeps up as dots are added (1 → 4) on 'يزيدوا'.","speaker":"الراوي","tts_text":"والشد ده ليه مقياس: الـ magnetic moment، وبيزيد كل ما الـ unpaired يزيدوا.","screen_text":"Magnetic moment ↑ with the number of unpaired electrons"},{"id":"a3l8","visual":"Three YK.momentMeter gauges LTR at x 960 / 1310 / 1660, y 560, r 140, labels 'Zn', 'Ni^2+', 'Fe^2+' under them; needles set on 'صفر' (0), 'اتنين' (2), 'أربعة' (4). Book p.14 exercise table.","speaker":"الراوي","tts_text":"الـ zinc صفر، والـ nickel two اتنين، والـ iron two أربعة.","screen_text":"Zn: 0 · Ni²⁺: 2 · Fe²⁺: 4 unpaired"},{"id":"a3l9","visual":"MISCONCEPTION: text panel 'FeCl₃ → Fe³⁺: [Ar] 3d⁵ → 5' in mint (big) on 'ion'; a smaller coral 'Fe atom: 4' with YK.wrongMark on 'atom' (≤ 1 s). Book p.14 exercise (FeCl₃).","speaker":"الراوي","tts_text":"وخدوا بالكم: بنعد الـ unpaired في الـ ion، مش في الـ atom نفسه.","screen_text":"Count in the ion: FeCl₃ → Fe³⁺ = 5, not the atom’s 4","pause_after_s":1},{"id":"a3l10","visual":"[SCENE 3c · te.metallic-properties, te.high-melting-points · new: — (metallic bond = prereq chip)] WIDE: the street tiles turn metallic (steel gradient + sheen sweep on 'بتلمع'); a heat glow and a small current arrow run along the row on 'الحرارة' / 'والكهربا'. Book p.13 point 3a.","speaker":"الراوي","tts_text":"وكل الجيران metals: solid، بتلمع، وبتوصّل الحرارة والكهربا كويس.","screen_text":"Metallic: solid · metallic lustre · good conductors of heat and electricity"},{"id":"a3l11","visual":"Fe tile heats red (heatRed tint); YK.counter 0 → 1538 ' °C' drawn with YK.label (mono digits) from 'ألف'. Book table p.12.","speaker":"الراوي","tts_text":"والـ melting point عالي: الحديد بيدوب عند ألف خمسمية تمانية وتلاتين درجة.","screen_text":"Fe: melting point 1538 °C"},{"id":"a3l12","visual":"CLOSE-UP: YK.lattice Fe (rows 4, cols 7) with sea {count 40, t}: sea dots split cyan (labelled '4s') and violet (labelled '3d'), both flow between the discs on 'بيشاركوا'. YK.prereqChip 'Metallic bond' ≤ 8 s. Book p.13 point 3b.","speaker":"الراوي","tts_text":"السبب: الـ four s والـ three d بيشاركوا في الـ metallic bond سوا.","screen_text":"4s + 3d electrons share in the metallic bond","pause_after_s":1},{"id":"a3l13","visual":"[SCENE 3d · te.atomic-radius · new: —] TWO-SHOT: Ferro left, Mana right, both discs at r ∝ book radius (equal on screen), dashed radius rings + labels '1.17 Å' / '1.16 Å' on 'الحجم'. Book table p.12.","speaker":"مانا","tts_text":"وفي حاجة كمان: أنا وفيرّو تقريباً نفس الحجم بالظبط.","screen_text":"Mn: 1.17 Å · Fe: 1.16 Å"},{"id":"a3l14","visual":"A row of six discs Cr → Cu (YK.atomDisc, r ∝ book radius 1.17 → 1.17) slides in LTR under the two-shot; a flat gold line touches their tops on 'ثابت'. Book p.12.","speaker":"الراوي","tts_text":"من الـ chromium لحد الـ copper، الـ atomic radius تقريباً ثابت.","screen_text":"Atomic radius: nearly constant (Cr → Cu)"},{"id":"a3l15","visual":"CLOSE-UP: YK.tug(ctx, 1300, 560, 220, {el:'Fe', pull: prog('attraction'), push: prog('repulsion'), labels:{pull:'Nuclear attraction', push:'3d repulsion'}}); ring holds steady on 'فبيتعادلوا'. Book pp.12–13.","speaker":"الراوي","tts_text":"الـ nuclear attraction بتزيد، والـ repulsion بين electrons الـ three d بتزيد… فبيتعادلوا.","screen_text":"Nuclear attraction ↑ · repulsion between 3d electrons ↑ → radius nearly constant","pause_after_s":1},{"id":"a3l16","visual":"[SCENE 3e · te.catalytic-activity · new: Haber–Bosch, activation energy (prereq chip)] ESTABLISHING WIDE: an ammonia plant at night (custom silhouette: towers, pipes, steam), camera push into a reactor window; equation strip at y 900: 'N_2 + 3H_2 ->[Fe|500 °C / 200 atm] 2NH_3' on 'Haber-Bosch'. Book p.15.","speaker":"الراوي","tts_text":"آخر محطة: مصنع ammonia بطريقة Haber-Bosch، وفيرّو هو الـ catalyst هناك.","screen_text":"Haber–Bosch: N₂ + 3H₂ → 2NH₃ (Fe)"},{"id":"a3l17","visual":"MEDIUM: YK.surface(ctx, 1300, 640, 900, {metal:'Fe', cols:8, molecules:[N2 col 2, H2 col 4, H2 col 6] p 0 → 1}); Ferro = the surface atom at col 4, drawn as YK.character (r 90, tag 'Ferro') so his glow/tag show; molecules approach on 'تعالوا'.","speaker":"فيرّو","tts_text":"تعالوا اقعدوا على سطحي… وأنا هسهّل عليكم الموضوع.","screen_text":"Fe catalyst surface"},{"id":"a3l18","visual":"Molecules adsorbed (p = 1) on 'بيربطوا'; short gold bond ticks from the surface atoms to each molecule. Book p.15.","speaker":"الراوي","tts_text":"الـ electrons بتوع الـ four s والـ three d بيربطوا الـ molecules بالسطح.","screen_text":"4s and 3d electrons form bonds with the reacting molecules"},{"id":"a3l19","visual":"More molecules settle on 'concentration'; stretch 0 → 1 on 'تضعف' (bonds lengthen, thin, dash).","speaker":"الراوي","tts_text":"فالـ concentration على السطح بتزيد، والـ bonds اللي جواها تضعف.","screen_text":"Concentration on the surface ↑ · bonds weaken"},{"id":"a3l20","visual":"Text panel: YK.energyProfile(ctx, 96, 300, 640, 520, {peak (without catalyst) drawn first, peak2 (with catalyst) on 'تقل'}), labels 'without catalyst' / 'with catalyst'; YK.prereqChip 'Activation energy' ≤ 8 s. Book fig 1-3.","speaker":"الراوي","tts_text":"فالـ activation energy تقل، والتفاعل يمشي أسرع بكتير.","screen_text":"Activation energy ↓ → faster reaction"},{"id":"a3l21","visual":"[SCENE 3f · te.catalysis-examples · new: hydrogenation · ✕ catalyst used up] TWO-SHOT insert: Mana (right, r 130) beside a YK.beaker with O₂ bubbles rising on 'بيسرّع'; label '2H_2O_2 ->[MnO_2] 2H_2O + O_2'. Book p.15 fig 1-3.","speaker":"مانا","tts_text":"وأنا كمان: الـ manganese dioxide بتاعي بيسرّع تكسير الـ hydrogen peroxide بسهولة.","screen_text":"MnO₂: decomposition of H₂O₂"},{"id":"a3l22","visual":"Two small cards slide in LTR on their cue words: 'Ni → hydrogenation of oils' on 'nickel', 'V₂O₅ → sulphuric acid (contact method)' on 'vanadium'. Book pp.14–15.","speaker":"الراوي","tts_text":"والـ nickel في الـ hydrogenation، والـ vanadium pentoxide في الـ sulphuric acid برضه.","screen_text":"Ni: hydrogenation · V₂O₅: sulphuric acid (contact method)"},{"id":"a3l23","visual":"MISCONCEPTION: coral small text '✕ used up' over a ghost of Ferro fading (≤ 1 s); then the real Ferro on the surface glows on 'فيرّو'.","speaker":"الراوي","tts_text":"ناس كتير فاكرة إن الـ catalyst بيخلص في التفاعل… بس بصّوا على فيرّو.","screen_text":"✕ A catalyst is used up"},{"id":"a3l24","visual":"NH₃ molecules (YK.molecule NH3) leave up-right (leave 0 → 1); Ferro unchanged, HUD identical, YK.rightMark + 'unchanged' tag; a new N₂ arrives at the edge.","speaker":"فيرّو","tts_text":"خارج زي ما دخلت بالظبط… ومستعد للدفعة الجاية.","screen_text":"Catalyst: unchanged ✓","pause_after_s":1.5},{"id":"f1","visual":"[FINALE · big question answered + labelled teaser (last line only)] Back to the night bridge (grade cold → finale), Ferro small on the girder; question card top-left; YK.flow first node 'Partly filled 3d' (explicit x/y, row 1 at y 620) on 'three'.","speaker":"الراوي","tts_text":"نجاوب السؤال: سر فيرّو كله في three d مش كاملة.","screen_text":"How do 4 unpaired electrons shape iron?"},{"id":"f2","visual":"YK.flow nodes appear on their cue words, two rows (≥ 32 px): row 1 'Partly filled 3d' → 'Several oxidation states' (on 'oxidation'); row 2 'Paramagnetic' (on 'paramagnetic') and 'Catalyst' (on 'catalyst'), edges from the first node; all nodes English.","speaker":"الراوي","tts_text":"منها oxidation states كتير، وشخصية paramagnetic، وشغل الـ catalyst كمان.","screen_text":"Several oxidation states · paramagnetic · catalyst"},{"id":"f3","visual":"Ferro centre, the 4 gold sparks circle his disc again; on 'صخرة' his rim tints hematite red for a beat.","speaker":"فيرّو","tts_text":"كل ده من أربعة لوحدهم… بس أنا كنت لسه صخرة حمرا.","screen_text":"The Lonely Four"},{"id":"f4","visual":"LABELLED TEASER (last line only): card 'Part 2: From Rock to Bridge' (Cairo 1000 72) on 'الجزء'; a hematite rock silhouette morphs into the bridge girder; fade out. Hold to the end (+0.8 s tail).","speaker":"الراوي","tts_text":"إزاي الصخرة دي بقت كوبري؟ ده في الجزء التاني: من الصخرة للكوبري.","screen_text":"Part 2: From Rock to Bridge"}],"logline":"Part 1 of 2. Ferro, an iron atom in a Cairo steel bridge, shows how four unpaired 3d electrons give iron its personality: its address in the d-block, its configuration, the ions it forms, its magnetism and its work as a catalyst.","characters":[{"name":"الراوي","voice":"ar-eg-training-5","persona":"Narrator (off-screen): documentary storyteller, warm Cairo Egyptian, dry wit; frames scenes, never re-explains what a character just showed. Run main voice (voice-narrator-main)."},{"name":"فيرّو","voice":"voice_4gyhs39ra0fj","persona":"Ferro, an Fe atom (Z = 26), the hero: young Cairo man, confident, funny, a bit vain about his magnetism; on-screen tag \"Ferro\" (voice-movie-ferro). Few English words per line (this voice drops English terms)."},{"name":"مانا","voice":"ar-eg-tutor-7","persona":"Mana, an Mn atom (Z = 25): calm, precise, dry deadpan humour, the half-filled perfectionist; on-screen tag \"Mana\" 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بالليل كوبري steel شايل آلاف\nالعربيات ومحدش واخد باله منه\nجوه الـ steel ده مليارات ذرات حديد وواحدة\nمنهم عندها حكاية\nإنتو فاكرين الحديد ده عادي أنا كنت صخرة\nحمرا في الصحرا\nأنا فيرّو ذرة حديد وسري كله في الأربعة\nاللي لوحدهم جوايا\nأربع electrons unpaired في الـ three d\nبتاعته دول أبطال الحكاية الحقيقيين\nوالسؤال إزاي أربع electrons unpaired يدّوا\nالحديد شخصيته كلها\nالحكاية بتبدأ في مدينة غريبة اسمها الـ\nperiodic table وفيرّو ساكن فيها\nالـ s-block على الشمال والـ p-block على\nاليمين والحي اللي في النص ده بتاعنا\nده حي الـ transition elements أكتر من ستين\nعنصر يعني أكتر من نص العناصر\nوالحي ده نوعين الأول main transition\nelements في النص بالظبط\nوالتاني inner transition elements في\nالصفين اللي تحت ودول مش موضوعنا\nالـ main transition elements هما الـ\nd-block عشر columns جنب بعض\nعشر بالظبط عشان الـ d-sublevel بياخد لحد\nعشرة electrons مش أكتر\nوالـ group eight لوحده واخد تلات columns\nوفيرّو ساكن في أولهم\nوالحي فيه أربع شوارع كل شارع transition\nseries بيملا d-sublevel مختلف\nشارع فيرّو هو الـ first transition series\nبيملا three d في period أربعة\nعشر جيران في الشارع من الـ scandium في\nالأول لحد الـ zinc في الآخر\nكل جار ليه شغلانة الـ chromium للـ plating\nوالـ zinc بيحمي الحديد من الصدا\nودي بطاقتي الشخصية بصّوا على العنوان بتاعي\nكويس\nالأول الـ argon core والـ four s فيها\nاتنين والـ three d ستة\nوالـ three d بتتملي حسب Hund's rule واحد\nفي كل orbital والـ pairing بعدها\nوأنا الـ manganese جارته عندي خمسة بالظبط\nكل orbital فيه واحد\nوأنا السادس عندي دخل على أول واحد فاضل\nأربعة لوحدهم\nأربعة unpaired ودول الأربعة اللي في اسم\nالفيلم\nطب جارهم الـ chromium المتوقع four s اتنين\nو three d أربعة\nبس الـ chromium مش كده خالص تفتكروا هو\nعامل إزاي فكّروا\nالـ chromium بيكسر التوقع four s واحد والـ\nthree d خمسة\nالاتنين بقوا half-filled وده بيدّي extra\nstability للـ atom كله\nشايفين الـ half-filled ده ستايلي أنا كمان\nوالـ copper برضه الـ four s واحد والـ\nthree d بقت filled بعشرة\nفي الشارع ده الذرات بتدّي electrons بسهولة\nبس مين بيطلع الأول\nأنا هخسر اتنين دلوقتي وإنتو شوفوا مين اللي\nهيمشي الأول\nناس كتير فاكرة إن آخر اتنين دخلوا الـ\nthree d هما اللي هيطلعوا\nغلط الـ four s هي الـ outer level فالاتنين\nبتوعها بيطلعوا الأول\nخسرت اتنين وأنا لسه زي ما أنا الأربعة لسه\nمعايا\nده الـ iron two وزائد اتنين دي اسمها الـ\noxidation state بتاعه\nكل الجيران عندهم زائد اتنين ما عدا الـ\nscandium لوحده\nوأعلى oxidation state بتطلع من الـ\nscandium لحد مانا عند زائد سبعة\nسبعة ده الرقم القياسي بتاعي وبعدي الأرقام\nبتنزل لحد زائد اتنين\nوأنا بقى أنا ممكن أخسر التمانية كلهم وأبقى\nزائد تمانية\nلأ يا فيرّو الحديد مبيوصلش لزائد تمانية\nوالمهمين عنده اتنين وتلاتة بس\nطب ليه عندهم oxidation states كتير كده الـ\nvanadium هيورّينا السلم بتاعه\nالطاقة اللي بتشيل كل electron اسمها\nionization potential وبتزيد بالتدريج\nمن ستمية تمانية وأربعين لحد ستة آلاف\nخمسمية تلاتة وعشرين من غير قفزة كبيرة\nعشان الـ four s والـ three d قريبين من بعض\nفي الطاقة\nبس مش كل اللي ساكن في الشارع ده يبقى واحد\nمننا رسمي\nالـ transition element عنصر الـ d-orbitals\nبتوعه فيها electrons بس مش كاملة\nمش كاملة في الـ atom نفسه أو في oxidation\nstate من بتوعه\nالـ scandium مثلا الـ three d فيها واحد بس\nيبقى transition element أكيد\nوالـ copper الـ three d عنده عشرة كاملة\ntransition ولا لأ فكّروا\nأيوه الـ copper لما يخسر اتنين الـ three d\nبتبقى تسعة مش كاملة\nوالـ zinc الـ three d عنده عشرة في الـ\natom وفي الـ ion كمان\nفالـ zinc مش transition element وبيسيب\nالشارع بهدوء\nأما أنا ممكن أخسر واحد كمان وأبقى مرتاح\nأكتر\nبعد التالت الـ three d بقت خمسة\nhalf-filled وده more stable بكتير\nمانا تعالي اعمليها زيي اخسري واحد كمان\nوارتاحي\nمانا دلوقتي manganese two هتخسر واحد كمان\nزي فيرّو فكّروا\nلأ شكرا الـ three d بتاعتي خمسة\nhalf-filled وأنا مرتاحة كده\nعشان كده الـ iron two بيحصله oxidation\nبسهولة والـ manganese two لأ\nفيرّو عنده هواية غريبة أي magnet بيشده\nناحيته على طول\nمش ذنبي إني جذاب دي الأربعة اللي جوايا\nالـ electrons الـ unpaired بتعمل magnetic\nfield صغير فبتتشد للـ magnetic field\nالخارجي\nوالمادة اللي بتتشد كده اسمها paramagnetic\nوفيرّو paramagnetic من الدرجة الأولى\nطب الـ zinc كل الـ electrons بتوعه paired\nالـ magnet هيشده فكّروا\nلأ الـ zinc diamagnetic بيتنفر من الـ\nmagnetic field شوية\nوالشد ده ليه مقياس الـ magnetic moment\nوبيزيد كل ما الـ unpaired يزيدوا\nالـ zinc صفر والـ nickel two اتنين والـ\niron two أربعة\nوخدوا بالكم بنعد الـ unpaired في الـ ion\nمش في الـ atom نفسه\nوكل الجيران metals solid بتلمع وبتوصّل\nالحرارة والكهربا كويس\nوالـ melting point عالي الحديد بيدوب عند\nألف خمسمية تمانية وتلاتين درجة\nالسبب الـ four s والـ three d بيشاركوا في\nالـ metallic bond سوا\nوفي حاجة كمان أنا وفيرّو تقريبا نفس الحجم\nبالظبط\nمن الـ chromium لحد الـ copper الـ atomic\nradius تقريبا ثابت\nالـ nuclear attraction بتزيد والـ\nrepulsion بين electrons الـ three d بتزيد\nفبيتعادلوا\nآخر محطة مصنع ammonia بطريقة Haber-Bosch\nوفيرّو هو الـ catalyst هناك\nتعالوا اقعدوا على سطحي وأنا هسهّل عليكم\nالموضوع\nالـ electrons بتوع الـ four s والـ three d\nبيربطوا الـ molecules بالسطح\nفالـ concentration على السطح بتزيد والـ\nbonds اللي جواها تضعف\nفالـ activation energy تقل والتفاعل يمشي\nأسرع بكتير\nوأنا كمان الـ manganese dioxide بتاعي\nبيسرّع تكسير الـ hydrogen peroxide بسهولة\nوالـ nickel في الـ hydrogenation والـ\nvanadium pentoxide في الـ sulphuric acid\nبرضه\nناس كتير فاكرة إن الـ catalyst بيخلص في\nالتفاعل بس بصّوا على فيرّو\nخارج زي ما دخلت بالظبط ومستعد للدفعة\nالجاية\nنجاوب السؤال سر فيرّو كله في three d مش\nكاملة\nمنها oxidation states كتير وشخصية\nparamagnetic وشغل الـ catalyst كمان\nكل ده من أربعة لوحدهم بس أنا كنت لسه صخرة\nحمرا\nإزاي الصخرة دي بقت كوبري ده في الجزء\nالتاني من الصخرة للكوبري","countable":true,"series_id":"chem-s3-en.movie-ferro","episode_no":1,"episode_count":2},{"id":"chem-s3-en.video-movie-ferro-2","kind":"movie","version":3,"ord":525,"group_id":"chem-s3-en.movie-ferro","part":2,"content_lang":"ar-EG","primary_concept_id":"fe.blast-furnace-reduction","concepts":[{"concept_id":"fe.blast-furnace-reduction","role":"primary"},{"concept_id":"alloy.definition-preparation","role":"secondary"},{"concept_id":"alloy.intermetallic","role":"secondary"},{"concept_id":"alloy.interstitial","role":"secondary"},{"concept_id":"alloy.substitutional","role":"secondary"},{"concept_id":"fe.midrex-reduction","role":"secondary"},{"concept_id":"fe.occurrence","role":"secondary"},{"concept_id":"fe.ore-dressing","role":"secondary"},{"concept_id":"fe.ores","role":"secondary"},{"concept_id":"fe.oxide-fe2o3","role":"secondary"},{"concept_id":"fe.oxide-fe3o4","role":"secondary"},{"concept_id":"fe.oxide-feo","role":"secondary"},{"concept_id":"fe.passivity","role":"secondary"},{"concept_id":"fe.physical-properties","role":"secondary"},{"concept_id":"fe.reaction-dilute-acids","role":"secondary"},{"concept_id":"fe.reactions-air-steam","role":"secondary"},{"concept_id":"fe.roasting","role":"secondary"},{"concept_id":"fe.steel-production","role":"secondary"},{"concept_id":"te.chromium-oxide-layer","role":"secondary"}],"title":"From Rock to Bridge","payload":{"part":2,"title":"From Rock to Bridge","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"16:9","format":"movie","script":[{"id":"r1","visual":"[RECAP (≤ 20 s) · Part 1 prerequisites this part needs: first series, Fe²⁺/Fe³⁺, near-constant radius] FRAME 0 (t=0): recap montage, grade cold, small chip 'Previously' top-left. The first-series strip Sc → Zn (YK.dBlockZoom p:1, names:1), the Fe tile glows gold and a small Ferro (tag 'Ferro') sits on it.","speaker":"الراوي","tts_text":"اللي فات: فيرّو ذرة حديد، ساكن في الـ first transition series بتاعتنا.","screen_text":"Previously: The Lonely Four"},{"id":"r2","visual":"Ferro's HUD: charge 2 on 'اتنين' (4s electrons fly off), then charge 3 on 'تلاتة' (remove = lerp(2/3, 1, p)); labels 'Fe^2+' then 'Fe^3+  [Ar] 3d^5'.","speaker":"الراوي","tts_text":"بيخسر اتنين أو تلاتة electrons، ويبقى iron two أو iron three بسهولة.","screen_text":"Fe²⁺ · Fe³⁺"},{"id":"r3","visual":"Row of discs Cr → Cu at equal radii (book p.12), flat gold line over their tops on 'ثابت'.","speaker":"الراوي","tts_text":"وحجمه تقريباً زي جيرانه: الـ atomic radius تقريباً ثابت.","screen_text":"Atomic radius: nearly constant","pause_after_s":1},{"id":"c1","visual":"[COLD OPEN · big question] Night steel bridge (same set as Part 1), camera pulls back fast (rewind feel: YK.camera 1.2 → 0.9) and the frame cross-fades to the desert at dawn on 'الرحلة'.","speaker":"الراوي","tts_text":"ودلوقتي نرجع لأول الرحلة، قبل الكوبري والمصنع والنار.","screen_text":"From Rock to Bridge"},{"id":"c2","visual":"WIDE desert dawn; a red hematite boulder (YK.ore hematite r 260, label:false) on the right; Ferro's disc (r 120, tag 'Ferro') glows faintly inside it.","speaker":"فيرّو","tts_text":"زمان، أنا كنت صخرة حمرا في الصحرا… ومحدش كان شايفني.","screen_text":"Ferro"},{"id":"c3","visual":"Text panel left: big question (Cairo 1000 64). After the line: YK.titleCard({title:'From Rock to Bridge', subtitle:'Part 2 of 2'}) ≤ 2.5 s.","speaker":"الراوي","tts_text":"والسؤال: إزاي صخرة حمرا بقت كوبري؟","screen_text":"How does a red rock become a bridge?","pause_after_s":2},{"id":"a4l1","visual":"[ACT 4 · SCENE 4a · fe.occurrence · new: iron ore] YK.actCard({num:4, title:'From Rock to Fire', size:100}) ≤ 2.5 s, then ESTABLISHING WIDE: Western Desert cross-section (crust layers). Four EQUAL rank tiles LTR 'O', 'Si', 'Al', 'Fe' (no bar heights: the book gives only the rank) — the Fe tile lights gold on 'رابع'; tag '5% by mass' on 'بخمسة'. Grade act4. Book p.16.","speaker":"الراوي","tts_text":"في الـ crust بتاع الأرض، الحديد رابع عنصر… بخمسة في المية من الكتلة.","screen_text":"Iron: 4th in Earth's crust · 5% by mass"},{"id":"a4l2","visual":"O / Si / Al tiles light on their cue words; on 'meteorites' a meteorite streaks in top-right with tag 'Pure iron (90%): meteorites'. Book p.16.","speaker":"الراوي","tts_text":"قبله الـ oxygen، والـ silicon، والـ aluminum… والحديد النقي في الـ meteorites بس.","screen_text":"After O, Si, Al · pure iron (90%): only in meteorites"},{"id":"a4l3","visual":"MEDIUM: cut-away of the hematite boulder: Ferro (YK.character Fe, charge badge 3+, HUD charge 3 = [Ar] 3d⁵) bound to red O discs; grey impurity grains around.","speaker":"فيرّو","tts_text":"أنا كنت جوه صخرة، مربوط في oxygen ومتخلط بحاجات تانية كتير.","screen_text":"Ferro inside the rock"},{"id":"a4l4","visual":"Labels on cue: 'iron ore' (title, text panel) on 'ore', 'iron oxides' pointing at Fe–O, 'impurities' at the grey grains on 'impurities'. Book p.16. [v5 facts fix: the title card reads 'Iron ore: iron compounds (mostly oxides)' (siderite is a carbonate, book p.16); the 'iron oxides' pointer on this red rock stays.]","speaker":"الراوي","tts_text":"الصخرة دي iron ore: فيها iron oxides متخلطة مع impurities كتير.","screen_text":"Iron ore: iron compounds (mostly oxides)"},{"id":"a4l5","visual":"Text panel YK.list LTR, 3 items on their cue words: 'Iron percentage', 'Composition of the impurities', 'Harmful elements: S, P, As'. Book p.16.","speaker":"الراوي","tts_text":"وصلاحية الـ ore بتعتمد على نسبة الحديد، والـ impurities، والعناصر الضارة اللي فيه.","screen_text":"Suitability: iron % · impurities · harmful elements (S, P, As)","pause_after_s":1},{"id":"a4l6","visual":"[SCENE 4b · fe.ores (one book table, one row per line) · new: hematite, limonite] ORES TABLE (one book table, built one row per line, stays on screen; book row order): 4 rows × cells [rock (YK.ore), name, chemical name, formula, colour, % Fe, place]. Row 1 'Hematite' builds on 'hematite': YK.ore hematite + 'Iron III oxide' + 'Fe₂O₃' + 'blood red'. Book p.16 table.","speaker":"الراوي","tts_text":"فيرّو كان في الـ hematite: iron three oxide، أحمر زي الدم.","screen_text":"Hematite · Iron III oxide · Fe₂O₃ · blood red"},{"id":"a4l7","visual":"Row 1 cells '50–60' (on 'خمسين') and 'Oasis area (western desert)' (on 'الواحات') fill; Ferro's small disc sits in the hematite cell, glowing while he speaks.","speaker":"فيرّو","tts_text":"من خمسين لستين في المية حديد… وعنواني منطقة الواحات.","screen_text":"50–60% · Oasis area (Western Desert)"},{"id":"a4l8","visual":"Row 2 'Limonite' builds on 'limonite': YK.ore limonite, 'Hydrated iron III oxide', '2Fe₂O₃·3H₂O', 'yellow', '20–60', 'Oasis area'.","speaker":"الراوي","tts_text":"والـ limonite الأصفر: iron three oxide ومعاه مية، من عشرين لستين في المية.","screen_text":"Limonite · 2Fe₂O₃·3H₂O · yellow · 20–60% · Oasis area"},{"id":"a4l9","visual":"[SCENE 4b′ · fe.ores (same table) · new: magnetite, siderite] Row 3 'Magnetite' builds on 'magnetite': YK.ore magnetite (rimmed), 'Magnetic iron oxide', 'Fe₃O₄', 'black, magnetic', '45–70', 'Eastern desert'; a tiny magnet icon tugs the rock on YK.cue('a4l9','properties') (needle 'magnetic' would hit 'magnetite' first).","speaker":"الراوي","tts_text":"والـ magnetite أسود، وليه magnetic properties، وموجود في الـ Eastern Desert عندنا.","screen_text":"Magnetite · Fe₃O₄ · black · magnetic · 45–70% · Eastern Desert"},{"id":"a4l10","visual":"Row 4 'Siderite' builds on 'siderite': YK.ore siderite, 'Iron II carbonate', 'FeCO₃', 'yellowish grey', '30–42', '---'; tag 'carbonate, not an oxide' on 'carbonate'. Finished table holds 1 s.","speaker":"الراوي","tts_text":"والـ siderite رمادي مصفر، وده iron two carbonate مش oxide خالص.","screen_text":"Siderite · Iron II carbonate · FeCO₃ · yellowish grey · 30–42%","pause_after_s":1},{"id":"a4l11","visual":"[SCENE 4c · fe.ore-dressing · new: ore dressing, sintering] WIDE: a processing yard at sunrise (industry kit set), conveyor in; Ferro (r 120) rides a hematite lump on the belt (left → right).","speaker":"فيرّو","tts_text":"بس أنا ماينفعش أدخل الفرن كده… لازم أتجهز الأول.","screen_text":"Ore dressing"},{"id":"a4l12","visual":"Title 'Ore dressing' in the text panel on 'ore'; YK.crusher(ctx, 1300, 560, 520, {p: prog('نكسّر'), type:'hematite'}); item 'a- Crushing' on 'crushing'. Book p.17.","speaker":"الراوي","tts_text":"أول خطوة اسمها ore dressing، وأولها الـ crushing: نكسّر الصخر لحجم مناسب.","screen_text":"Ore dressing: a- crushing (a suitable size)"},{"id":"a4l13","visual":"YK.sinter(ctx, 1300, 600, 640, {p: prog('sintering')}); fines fuse into a few lumps; item 'b- Sintering' on 'sintering'.","speaker":"الراوي","tts_text":"الـ crushing بيطلّع fine particles كتير، فبنعمل sintering: نلمها في حتت أكبر.","screen_text":"b- Sintering: fine particles → larger, homogeneous lumps"},{"id":"a4l14","visual":"[SCENE 4c′ · fe.ore-dressing · new: concentrating] Item 'c- Concentrating' on 'concentrating'; a % Fe gauge (YK.ore gauge on a magnetite lump) rises on 'تعلى'.","speaker":"الراوي","tts_text":"وبعدين الـ concentrating: نشيل أغلب الـ impurities، فنسبة الحديد تعلى.","screen_text":"c- Concentrating: removes impurities → iron % ↑"},{"id":"a4l15","visual":"YK.magSeparator(ctx, 1300, 560, 220, {p: prog(YK.cue('a4l15','separation')), labels:{ore:'Ore', waste:'Impurities'}} (needle 'magnetic' hits 'magnetite' first)): ore grains ride the drum to the right bin, impurities fall left. Book p.17 (magnetic separation).","speaker":"الراوي","tts_text":"ومع الـ magnetite بنستخدم magnetic separation: الخام بيتشد، والـ impurities بتقع.","screen_text":"Magnetic separation","pause_after_s":1},{"id":"a4l16","visual":"[SCENE 4d · fe.roasting · new: roasting] YK.kiln(ctx, 820, 300, 1000, 420, {heat: prog('نسخّن'), gases:[]}) — gases added per line below; title 'Roasting' on 'roasting'. Book p.17.","speaker":"الراوي","tts_text":"تاني خطوة الـ roasting: نسخّن الخام جامد في الهوا.","screen_text":"Roasting: the ore is strongly heated in air"},{"id":"a4l17","visual":"Kiln gas 'H₂O' leaves the high end on 'الرطوبة'; % Fe gauge ticks up on 'تعلى'.","speaker":"الراوي","tts_text":"أولاً بننشّف الخام ونطلّع الرطوبة، فنسبة الحديد تعلى.","screen_text":"a) Drying, expelling humidity → iron % ↑"},{"id":"a4l18","visual":"Equation strip (stage, y 860), two rows LTR: 'FeCO_3 ->[Δ] FeO + CO_2' on 'siderite', '2FeO + 1/2O_2 ->[Δ] Fe_2O_3' on 'oxygen'; kiln gas 'CO₂'. Book p.17.","speaker":"الراوي","tts_text":"والـ siderite بيدّي iron two oxide، بياخد oxygen ويبقى iron three oxide بعدها.","screen_text":"FeCO₃ → FeO + CO₂ · 2FeO + ½O₂ → Fe₂O₃"},{"id":"a4l19","visual":"Kiln gas 'SO₂' leaves on 'sulphur'; a solid 'P₂O₅' speck drops out with the ore on 'phosphorus' (solid in the book). Book p.17.","speaker":"الراوي","tts_text":"وتانياً بنعمل oxidation للـ impurities، زي الـ sulphur والـ phosphorus كمان.","screen_text":"b) Oxidation of impurities: S → SO₂ · P → P₂O₅"},{"id":"a4l20","visual":"Ferro rolls out of the kiln mouth (left → right), cleaner red lump, HUD 'Fe^3+ [Ar] 3d^5', O discs still around him.","speaker":"فيرّو","tts_text":"طلعت من الفرن ده أنضف بكتير… ولسه الـ oxygen ماسكني.","screen_text":"Fe₂O₃: Fe³⁺, still bound to oxygen"},{"id":"a4l21","visual":"[SCENE 4e · fe.blast-furnace-reduction · new: blast furnace, coke · ◆ predict 1 · ✕ coke itself reduces] BIG MOVE of the act: ESTABLISHING WIDE of YK.furnace(ctx, 760, 120, 520, 860, {type:'blast', heat: prog, fill:1, labels:true}) then the camera falls into the charge (YK.camera zoom 1 → 2.2 on the reduction region). Grade heatRed → molten. Book p.18.","speaker":"الراوي","tts_text":"وصلنا للنار: الـ blast furnace، مليان coke وخام سخن.","screen_text":"Blast furnace"},{"id":"a4l22","visual":"TWO-SHOT: Ferro in the charge (left, r 120); Mana (r 120, tag 'Mana') watches from a furnace window inset on the right; Mana speaks (glow), Ferro dims.","speaker":"مانا","tts_text":"جيت أتفرج… بس قولولي: مين اللي هيشيل الـ oxygen من فيرّو؟","screen_text":"Who removes the oxygen?"},{"id":"a4l23","visual":"PREDICT ◆1. Coke lumps highlighted (furnace highlight:'charge'); question in the text panel; YK.thinkRing from 'فكّروا'.","speaker":"الراوي","tts_text":"الـ coke ده carbon… هل هو اللي بيشيل الـ oxygen بنفسه؟ فكّروا.","screen_text":"Does coke itself remove the oxygen?","pause_after_s":3},{"id":"a4l24","visual":"Coral '✕ coke itself' (small, ≤ 1 s) on 'لأ'; equation strip 'C + O_2 ->[Δ] CO_2' on 'بيتحرق'; CO₂ molecules (YK.molecule CO2) rise from burning coke. Book p.18.","speaker":"الراوي","tts_text":"لأ: الـ coke بيتحرق في الـ oxygen، ويبقى carbon dioxide سخن.","screen_text":"✕ Not coke itself · C + O₂ → CO₂"},{"id":"a4l25","visual":"Second strip row 'CO_2 + C ->[Δ] 2CO' on 'monoxide' (one-word needles only); each CO₂ touching coke turns into two CO (YK.molecule CO).","speaker":"الراوي","tts_text":"والـ carbon dioxide يقابل coke تاني، فيبقى carbon monoxide على طول.","screen_text":"CO₂ + C → 2CO"},{"id":"a4l26","visual":"The CO crew (YK.molecule CO swarm, silent) rises through the charge; each CO pulls one O off the ore near Ferro and leaves as CO₂ on 'بيشيل'; equation row '3CO + Fe_2O_3 ->[higher than 700 °C] 2Fe + 3CO_2' and furnace label '> 700°C' on 'سبعمية'. No zones, no slag (G46). Book p.18.","speaker":"الراوي","tts_text":"والـ carbon monoxide هو اللي بيشيل الـ oxygen، فوق سبعمية درجة.","screen_text":"3CO + Fe₂O₃ → 2Fe + 3CO₂ (higher than 700 °C)"},{"id":"a4l27","visual":"Term 'Reduction' in the text panel on 'reduction'; Ferro's HUD charge 3 with remove 1 → 0 from 'بياخد' (three electrons fly back in on arcs): '[Ar] 3d^5' → '[Ar] 4s^2 3d^6'.","speaker":"الراوي","tts_text":"وده اسمه reduction: الخام بيخسر الـ oxygen، وفيرّو بياخد تلات electrons تاني.","screen_text":"Reduction: loss of oxygen · Fe³⁺ gains 3 electrons → Fe"},{"id":"a4l28","visual":"Ferro mood proud; the 4 unpaired arrows glow gold on 'والأربعة'; molten iron tap stream at the furnace bottom (tap 0 → 1).","speaker":"فيرّو","tts_text":"رجعولي الـ electrons بتوعي… والأربعة رجعوا معايا!","screen_text":"Fe: [Ar] 4s² 3d⁶ · unpaired = 4"},{"id":"a4l29","visual":"[SCENE 4f · fe.midrex-reduction · new: Midrex furnace, water gas · ✕ methane itself reduces] Mana in her window (glow); Ferro dims. The coke in the furnace fades to 40%.","speaker":"مانا","tts_text":"طيب، ينفع نعمل كده من غير coke خالص؟","screen_text":"Without coke?"},{"id":"a4l30","visual":"CUT: YK.furnace(ctx, 760, 120, 520, 860, {type:'midrex', reformer:true, flow: prog}); label 'Midrex furnace' on 'Midrex'; tag 'natural gas: 93% CH₄' on 'methane'. Book p.18.","speaker":"الراوي","tts_text":"أيوه: الـ Midrex furnace بيستخدم natural gas، أغلبه methane، تلاتة وتسعين في المية.","screen_text":"Midrex furnace: natural gas (93% methane)"},{"id":"a4l31","visual":"Reformer box lights: equation strip '2CH_4 + CO_2 + H_2O ->[Δ] 3CO + 5H_2' on 'methane'; label 'water gas' on 'water'. Book p.18.","speaker":"الراوي","tts_text":"الـ methane بيدّي carbon monoxide و hydrogen… خليط اسمه water gas بالظبط.","screen_text":"CH₄ → CO + H₂ (water gas)"},{"id":"a4l32","visual":"CO + H₂ molecules rise through the shaft, pull O off the pellets (leave as CO₂ / H₂O) on 'بيشيل'; solid iron leaves the bottom on 'حديد'. Equation row under the first.","speaker":"الراوي","tts_text":"والـ water gas بيشيل الـ oxygen من الخام، ويطلع حديد برضه.","screen_text":"2Fe₂O₃ + 3CO + 3H₂ → 4Fe + 3CO₂ + 3H₂O"},{"id":"a4l33","visual":"Coral '✕ CH₄ reduces' (small, ≤ 1 s) then the arrow 'CH₄ → water gas → reduction' in mint, text panel.","speaker":"الراوي","tts_text":"والـ methane نفسه مش بيعمل reduction… هو مصدر الـ water gas بس.","screen_text":"✕ Methane itself does not reduce the ore","pause_after_s":1},{"id":"a4l34","visual":"[SCENE 4g · fe.steel-production · new: — · ✕ steel = pure iron] Ferro (r 150) exits the furnace onto a ladle edge, mood proud; coral '?' over 'steel'.","speaker":"فيرّو","tts_text":"طلعت حديد أخيراً! يعني بقيت steel خلاص؟","screen_text":"Iron = steel?"},{"id":"a4l35","visual":"Text panel two-step card LTR, item 1 on 'نشيل', item 2 on 'ونضيف' (book wording 'Removal of impurities' / 'Addition of some elements'). Book p.18.","speaker":"الراوي","tts_text":"لسه: الـ steel محتاج نشيل الـ impurities من الحديد، ونضيف elements معينة.","screen_text":"Steel: 1. remove impurities · 2. add some elements","pause_after_s":2},{"id":"a5l1","visual":"[ACT 5 · SCENE 5a · alloy.definition-preparation · new: alloy, ferromanganese] YK.actCard({num:5, title:'Stronger Together', size:100}) ≤ 2.5 s, then ESTABLISHING WIDE: steel mill interior, ladle pouring, sparks (YK.particles seeded), grade act5 steel + gold.","speaker":"الراوي","tts_text":"إضافة elements للحديد معناها إننا بنعمل alloy جديد.","screen_text":"ACT 5 · Stronger Together"},{"id":"a5l2","visual":"Term label 'Alloy' on 'alloy'; two molten streams (steel + violet) mix in a crucible on 'بنصهرهم', then cool (colour fades from molten to steel) on 'يبردوا'. Book p.19.","speaker":"الراوي","tts_text":"الـ alloy غالباً من اتنين metals أو أكتر، بنصهرهم سوا ونسيبهم يبردوا بالراحة.","screen_text":"Alloy: two metals or more · melting, then cooling gradually"},{"id":"a5l3","visual":"TWO-SHOT: Mana returns on the right (r 150, tag 'Mana', glow), Ferro left; behind them a railway track silhouette with tag 'Ferromanganese' on 'ferromanganese'. Book pp.6, 19.","speaker":"مانا","tts_text":"زي أنا والحديد: الـ ferromanganese، أصلب من الـ steel، وبيعملوا منه قضبان القطر.","screen_text":"Ferromanganese: railway tracks (harder than steel)"},{"id":"a5l4","visual":"Carbon zips in (YK.atomDisc el:'C', rimmed, half Ferro's size; silent; tag 'Carbon' ≤ 2 s, first appearance) on 'carbon'.","speaker":"الراوي","tts_text":"وممكن يبقى metal ومعاه nonmetal، زي الـ carbon الصغير ده.","screen_text":"Metal + nonmetal, e.g. carbon (steel)"},{"id":"a5l5","visual":"[SCENE 5b · alloy.interstitial · new: interstitial alloy · ◆ predict 2] CLOSE-UP: YK.lattice(ctx, 860, 260, 900, 560, {rows:5, cols:8, color:'#E0703A'}); YK.hammer strike on 'بالشاكوش', impact drives slip 0 → 1 (top layers slide). Ferro = one lattice atom with tag. Book p.19 fig 1-5 a, b.","speaker":"الراوي","tts_text":"الحديد النقي atoms مترصصة صفوف… ولو ضربناه بالشاكوش، الطبقات بتزحلق على بعض.","screen_text":"Pure iron: layers slip on hammering"},{"id":"a5l6","visual":"Ferro (in the lattice) shivers a little (mood shiver); the slipped layers stay offset.","speaker":"فيرّو","tts_text":"يعني لوحدي مش هستحمل… محدش هيبني بيا كوبري كده.","screen_text":"Pure iron alone"},{"id":"a5l7","visual":"PREDICT ◆2. Lattice resets (slip 0); Carbon hovers at a gap; question in the text panel; YK.thinkRing from 'فكّروا'.","speaker":"الراوي","tts_text":"طب الـ carbon الصغير ده، لو دخل بين الطبقات، هيعمل إيه؟ فكّروا.","screen_text":"Small carbon atoms between the layers: what happens?","pause_after_s":3},{"id":"a5l8","visual":"lattice insert [C at several gaps] (gold, scale 0.45) on 'المسافات'; hammer strikes again on 'مبتزحلقش' — slip stays 0, a gold lock line along the slip plane; tag 'harder' on 'أصلب'. Book p.19 fig 1-5 c.","speaker":"الراوي","tts_text":"بيقعد في المسافات الصغيرة، فالطبقات مبتزحلقش، والحديد يبقى أصلب بكتير.","screen_text":"Atoms in the spaces → layers cannot slip → harder"},{"id":"a5l9","visual":"Term label 'Interstitial alloy' on 'interstitial'; example tag 'Steel = iron + carbon' on 'steel'.","speaker":"الراوي","tts_text":"ده اسمه interstitial alloy، وأشهر مثال عليه: الـ steel، يعني carbon جوه الحديد.","screen_text":"Interstitial alloy: steel (iron + carbon)"},{"id":"a5l10","visual":"Ferro (glow) and Carbon side by side in the lattice; the gold lock line pulses.","speaker":"فيرّو","tts_text":"كده أقدر أشيل كوبري… أنا والـ carbon فريق واحد.","screen_text":"Fe + C"},{"id":"a5l11","visual":"[SCENE 5b′ · fe.physical-properties (after interstitial, map order) · new: —] Text panel: 'Pure iron: relatively soft' on 'soft'; 'steels and alloys' on 'alloys'. Book p.20 'Properties of Iron'.","speaker":"الراوي","tts_text":"والحديد النقي ملوش أهمية صناعية، عشان relatively soft… والـ alloys هي اللي بتشتغل.","screen_text":"Pure iron: relatively soft → no industrial importance"},{"id":"a5l12","visual":"YK.list LTR on cue words: 'malleable', 'ductile', 'magnetic', 'mp 1538 °C'; 'density 7.87 g/cm³' last (shown, not voiced). Book p.20.","speaker":"الراوي","tts_text":"وهو malleable و ductile و magnetic، وبيدوب عند ألف خمسمية تمانية وتلاتين.","screen_text":"Pure iron: malleable · ductile · magnetic · mp 1538 °C · 7.87 g/cm³","pause_after_s":1},{"id":"a5l13","visual":"[SCENE 5c · alloy.intermetallic · new: intermetallic alloy, cementite] CLOSE-UP: three Fe discs + one C snap into a fixed cluster (YK.molecule with custom atoms [Fe, Fe, Fe, C] + bonds) on 'بيتحدوا'; label 'Fe₃C (cementite)' on 'cementite'. Book p.20.","speaker":"الراوي","tts_text":"وأحياناً الحديد والـ carbon بيتحدوا كيميائياً… ويطلع compound اسمه الـ cementite ده.","screen_text":"Cementite Fe₃C"},{"id":"a5l14","visual":"Term label 'Intermetallic alloy' on 'intermetallic'; under it 'formula disobeys the valence law' on 'valence'. Book p.20.","speaker":"الراوي","tts_text":"ده intermetallic alloy، والـ formula بتاعته بتكسر قانون الـ valence خالص.","screen_text":"Intermetallic alloy: a chemical compound · formula disobeys the valence law","pause_after_s":1},{"id":"a5l15","visual":"[SCENE 5d · alloy.substitutional (callback: near-constant radius) · new: substitutional alloy] TWO-SHOT callback: Ferro and Mana equal-size discs with dashed rings (as in Part 1 recap r3); Mana speaks (glow).","speaker":"مانا","tts_text":"وفاكرين إن حجمنا تقريباً زي بعض؟ ده بيخلّي ذرات تانية تاخد مكان الحديد.","screen_text":"Similar atomic radius"},{"id":"a5l16","visual":"CLOSE-UP: YK.lattice with substitute [pink Cr atoms at 4 sites, scale 1] — they REPLACE Fe atoms in place (same size), on 'substitutional'; term label + book condition line. Book p.20.","speaker":"الراوي","tts_text":"ده substitutional alloy، ذراته ليها نفس الـ atomic radius والـ crystal lattice كمان.","screen_text":"Substitutional alloy: same atomic radius, crystal lattice and chemical properties"},{"id":"a5l17","visual":"Three example tags LTR on 'chromium', 'ferronickel', 'copper'. Book p.20.","speaker":"الراوي","tts_text":"زي الـ chromium في الـ stainless steel، والـ ferronickel، والـ copper مع الدهب.","screen_text":"Ferrochrome (stainless steel) · ferronickel · copper–gold","pause_after_s":1},{"id":"a5l18","visual":"[SCENE 5e · fe.reaction-dilute-acids · new: — · ◆ predict 3 · ✕ iron (III) salt] WIDE: a quality lab; Ferro (r 140, tag 'Ferro') on a bench in front of three in-world test stations LTR with English signs: 'Test 1: dilute acid', 'Test 2: conc. HNO₃', 'Test 3: heat + air / steam'; camera slides to station 1 on 'اختبارات'.","speaker":"فيرّو","tts_text":"قبل ما يركبوني في الكوبري، عملولي اختبارات كيميا كتير.","screen_text":"Before the bridge: three tests"},{"id":"a5l19","visual":"Lab cut: YK.beaker with dilute acid, an iron nail; H₂ bubbles rise on 'hydrogen'; equation stub 'Fe + H_2SO_4 (dil.) -> ? + H_2'. Book p.21.","speaker":"الراوي","tts_text":"أول اختبار: حطّوه في dilute sulphuric acid، وهتلاقوا hydrogen طالع.","screen_text":"Fe + dilute H₂SO₄ → ? + H₂"},{"id":"a5l20","visual":"PREDICT ◆3. Two choice chips 'iron (II) salt' / 'iron (III) salt' (YK.choice) in the text panel; YK.thinkRing from 'فكّروا'.","speaker":"الراوي","tts_text":"الملح اللي هيطلع: iron two ولا iron three؟ فكّروا.","screen_text":"Iron (II) salt or iron (III) salt?","pause_after_s":3},{"id":"a5l21","visual":"Ferro (small, at the beaker rim) speaks, mood proud; the 'iron (III) salt' chip glows coral — wrong idea said once, small.","speaker":"فيرّو","tts_text":"أكيد تلاتة! الـ half-filled ده أريح ليا.","screen_text":"Iron (III)? ✕"},{"id":"a5l22","visual":"YK.wrongMark on the coral chip on 'لأ'; 'iron (II) salt' chip glows mint; equation completes 'FeSO_4' on 'iron'; tag 'reduced by the hydrogen produced' on 'reduction'. Book p.21.","speaker":"الراوي","tts_text":"لأ: ملح iron two، عشان الـ hydrogen بيعمل reduction للـ iron three على طول.","screen_text":"Fe + H₂SO₄ (dil.) → FeSO₄ + H₂ · H₂ reduces iron (III)","pause_after_s":1},{"id":"a5l23","visual":"[SCENE 5f · te.chromium-oxide-layer → fe.passivity · new: nonporous, passivity] CLOSE-UP: YK.oxideSkin(ctx, 860, 400, 900, 360, {metal:'Cr', p:0}) — a Cr block in air; a chrome-plated tap icon on 'plating' (1-line callback to Cr's use, prereq te.uses-v-cr); tag 'chemically active' on 'نشيط'. Book p.6.","speaker":"الراوي","tts_text":"والـ chromium اللي بيستخدموه في الـ plating؟ metal نشيط، بس الهوا مبيأثرش فيه.","screen_text":"Chromium: active, yet resists the atmosphere"},{"id":"a5l24","visual":"oxideSkin p 0 → 1 on 'طبقة' (layer forms left → right), porous:false; air particles bounce off on 'بتقفل'. Book p.6.","speaker":"الراوي","tts_text":"عشان بيعمل طبقة oxide حجمها أكبر من الـ metal، nonporous، بتقفل عليه.","screen_text":"Oxide volume > metal → nonporous oxide layer"},{"id":"a5l25","visual":"Ferro pops up beside the Cr block (mood proud).","speaker":"فيرّو","tts_text":"وأنا كمان أقدر أعمل نفس الحيلة دي!","screen_text":"Iron?"},{"id":"a5l26","visual":"Camera slides to station 2. YK.oxideSkin(ctx, 860, 400, 900, 360, {metal:'Fe', p: prog('طبقة'), acid:1, acidLabel:'HNO3 (conc.)'}): acid particles bounce off the thin layer. Book p.21.","speaker":"الراوي","tts_text":"تاني اختبار: الـ concentrated nitric acid عمل على الحديد طبقة oxide رفيعة بتحميه.","screen_text":"Conc. HNO₃ → a thin oxide layer protects iron"},{"id":"a5l27","visual":"Term label 'Passivity' on 'passivity'; the layer scrapes off on 'بالحك' (a rub stroke), then tag 'dilute HCl' on 'hydrochloric'. Book p.21.","speaker":"الراوي","tts_text":"وده اسمه passivity، والطبقة بتتشال بالحك، أو بالـ dilute hydrochloric acid برضه.","screen_text":"Passivity · removed by abrasion or dilute HCl","pause_after_s":1},{"id":"a5l28","visual":"[SCENE 5g · fe.reactions-air-steam → fe.oxide-feo, fe.oxide-fe2o3 → fe.oxide-fe3o4 · new: —] Camera slides to station 3; Ferro glows red-hot (heatRed rim); O₂ molecules (air) on 'هوا', H₂O molecules (steam) on 'وبخار' approach him.","speaker":"فيرّو","tts_text":"وتالت اختبار: سخّنوني لحد ما احمرّيت، وجابولي هوا وبخار مية.","screen_text":"Test 3: red-hot iron + air or steam"},{"id":"a5l29","visual":"A black 'Fe₃O₄' crust grows on Ferro on 'magnetic'; equation rows LTR: '3Fe + 2O_2 ->[Δ] Fe_3O_4' then '3Fe + 4H_2O ->[500 °C] Fe_3O_4 + 4H_2' (H₂ bubbles on 'hydrogen'). Book p.21.","speaker":"الراوي","tts_text":"بيطلع الـ magnetic iron oxide، ومع البخار بيطلع hydrogen كمان.","screen_text":"3Fe + 2O₂ → Fe₃O₄ · 3Fe + 4H₂O (500 °C) → Fe₃O₄ + 4H₂"},{"id":"a5l30","visual":"Three oxide jars LTR (custom: jar + powder colour); jar 1 'FeO' black fills on YK.cue('a5l30','two'). Book p.22.","speaker":"الراوي","tts_text":"وللحديد تلات oxides: الـ iron two oxide، بودرة سودا.","screen_text":"Iron (II) oxide FeO: black powder"},{"id":"a5l31","visual":"Jar 2 'Fe₂O₃' red fills on YK.cue('a5l31','three'); a red paint stroke on 'البويات'; tiny hematite icon on 'hematite'. Book p.23.","speaker":"الراوي","tts_text":"والـ iron three oxide، اللي في الـ hematite، وبيدخل في البويات الحمرا.","screen_text":"Iron (III) oxide Fe₂O₃: hematite · red pigments in paints"},{"id":"a5l32","visual":"Jar 3 'Fe₃O₄' black (the product of test 3) splits visually into an FeO half and an Fe₂O₃ half on 'two' / 'three', then merges back; label 'magnetic iron oxide = magnetite'. Book p.23.","speaker":"الراوي","tts_text":"والتالت الـ magnetite: iron two oxide و iron three oxide مع بعض.","screen_text":"Fe₃O₄ (magnetite): mixed iron (II) and iron (III) oxides","pause_after_s":2},{"id":"f1","visual":"[FINALE · big question answered; last line Ferro] FINALE: the bridge at dawn (grade finale, gold light), camera slow pull-back; question card top-left.","speaker":"الراوي","tts_text":"ونرجع للكوبري مع أول النهار… ونجاوب السؤال.","screen_text":"How does a red rock become a bridge?"},{"id":"f2","visual":"YK.flow row 1 (explicit x/y, y 560, ≥ 32 px): 'Hematite' → 'Ore dressing' (on 'ore') → 'Roasting' (on 'roasting').","speaker":"الراوي","tts_text":"الصخرة اتجهزت: ore dressing، وبعده roasting في الهوا.","screen_text":"Hematite → ore dressing → roasting"},{"id":"f3","visual":"Flow continues row 2 (y 760): 'Reduction by CO' (on 'monoxide') → 'Iron' (on 'حديد'); edge from row 1's last node curves down.","speaker":"الراوي","tts_text":"وفي الـ blast furnace، الـ carbon monoxide شال الـ oxygen… فرجع حديد.","screen_text":"→ reduction by CO → iron"},{"id":"f4","visual":"Row 2 ends 'Steel' (on 'steel') → 'Bridge' (on 'الكوبري'); the bridge behind the chain catches the first sun.","speaker":"الراوي","tts_text":"وبالـ carbon بين الطبقات بقى steel… والـ steel شال الكوبري.","screen_text":"→ steel (interstitial alloy) → bridge"},{"id":"f5","visual":"Last line, Ferro: camera pushes to his atom in the girder; his 4 unpaired arrows glow gold on 'الأربعة'; end card 'The Lonely Four' small under the tag; hold through the tail.","speaker":"فيرّو","tts_text":"وكل ده من الأربعة اللي لوحدهم… ولسه معايا لحد النهارده.","screen_text":"The Lonely Four"}],"logline":"Part 2 of 2. Ferro remembers his journey from a blood-red hematite rock in the Western Desert, through ore dressing, roasting and the blast furnace, to the steel of a Cairo bridge: alloys, passivity and the oxides of iron.","characters":[{"name":"الراوي","voice":"ar-eg-training-5","persona":"Narrator (off-screen): documentary storyteller, warm Cairo Egyptian, dry wit; frames scenes, never re-explains what a character just showed. Run main voice (voice-narrator-main)."},{"name":"فيرّو","voice":"voice_4gyhs39ra0fj","persona":"Ferro, an Fe atom (Z = 26), the hero: young Cairo man, confident, funny, a bit vain about his magnetism; on-screen tag \"Ferro\" (voice-movie-ferro). Few English words per line (this voice drops English terms)."},{"name":"مانا","voice":"ar-eg-tutor-7","persona":"Mana, an Mn atom (Z = 25): calm, precise, dry deadpan humour, the half-filled perfectionist; on-screen tag \"Mana\" 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فات فيرّو ذرة حديد ساكن في الـ first\ntransition series بتاعتنا\nبيخسر اتنين أو تلاتة electrons ويبقى iron\ntwo أو iron three بسهولة\nوحجمه تقريبا زي جيرانه الـ atomic radius\nتقريبا ثابت\nودلوقتي نرجع لأول الرحلة قبل الكوبري\nوالمصنع والنار\nزمان أنا كنت صخرة حمرا في الصحرا ومحدش كان\nشايفني\nوالسؤال إزاي صخرة حمرا بقت كوبري\nفي الـ crust بتاع الأرض الحديد رابع عنصر\nبخمسة في المية من الكتلة\nقبله الـ oxygen والـ silicon والـ aluminum\nوالحديد النقي في الـ meteorites بس\nأنا كنت جوه صخرة مربوط في oxygen ومتخلط\nبحاجات تانية كتير\nالصخرة دي iron ore فيها iron oxides متخلطة\nمع impurities كتير\nوصلاحية الـ ore بتعتمد على نسبة الحديد\nوالـ impurities والعناصر الضارة اللي فيه\nفيرّو كان في الـ hematite iron three oxide\nأحمر زي الدم\nمن خمسين لستين في المية حديد وعنواني منطقة\nالواحات\nوالـ limonite الأصفر iron three oxide\nومعاه مية من عشرين لستين في المية\nوالـ magnetite أسود وليه magnetic\nproperties وموجود في الـ Eastern Desert\nعندنا\nوالـ siderite رمادي مصفر وده iron two\ncarbonate مش oxide خالص\nبس أنا ماينفعش أدخل الفرن كده لازم أتجهز\nالأول\nأول خطوة اسمها ore dressing وأولها الـ\ncrushing نكسّر الصخر لحجم مناسب\nالـ crushing بيطلّع fine particles كتير\nفبنعمل sintering نلمها في حتت أكبر\nوبعدين الـ concentrating نشيل أغلب الـ\nimpurities فنسبة الحديد تعلى\nومع الـ magnetite بنستخدم magnetic\nseparation الخام بيتشد والـ impurities\nبتقع\nتاني خطوة الـ roasting نسخّن الخام جامد في\nالهوا\nأولا بننشّف الخام ونطلّع الرطوبة فنسبة\nالحديد تعلى\nوالـ siderite بيدّي iron two oxide بياخد\noxygen ويبقى iron three oxide بعدها\nوتانيا بنعمل oxidation للـ impurities زي\nالـ sulphur والـ phosphorus كمان\nطلعت من الفرن ده أنضف بكتير ولسه الـ\noxygen ماسكني\nوصلنا للنار الـ blast furnace مليان coke\nوخام سخن\nجيت أتفرج بس قولولي مين اللي هيشيل الـ\noxygen من فيرّو\nالـ coke ده carbon هل هو اللي بيشيل الـ\noxygen بنفسه فكّروا\nلأ الـ coke بيتحرق في الـ oxygen ويبقى\ncarbon dioxide سخن\nوالـ carbon dioxide يقابل coke تاني فيبقى\ncarbon monoxide على طول\nوالـ carbon monoxide هو اللي بيشيل الـ\noxygen فوق سبعمية درجة\nوده اسمه reduction الخام بيخسر الـ oxygen\nوفيرّو بياخد تلات electrons تاني\nرجعولي الـ electrons بتوعي والأربعة رجعوا\nمعايا\nطيب ينفع نعمل كده من غير coke خالص\nأيوه الـ Midrex furnace بيستخدم natural\ngas أغلبه methane تلاتة وتسعين في المية\nالـ methane بيدّي carbon monoxide و\nhydrogen خليط اسمه water gas بالظبط\nوالـ water gas بيشيل الـ oxygen من الخام\nويطلع حديد برضه\nوالـ methane نفسه مش بيعمل reduction هو\nمصدر الـ water gas بس\nطلعت حديد أخيرا يعني بقيت steel خلاص\nلسه الـ steel محتاج نشيل الـ impurities من\nالحديد ونضيف elements معينة\nإضافة elements للحديد معناها إننا بنعمل\nalloy جديد\nالـ alloy غالبا من اتنين metals أو أكتر\nبنصهرهم سوا ونسيبهم يبردوا بالراحة\nزي أنا والحديد الـ ferromanganese أصلب من\nالـ steel وبيعملوا منه قضبان القطر\nوممكن يبقى metal ومعاه nonmetal زي الـ\ncarbon الصغير ده\nالحديد النقي atoms مترصصة صفوف ولو ضربناه\nبالشاكوش الطبقات بتزحلق على بعض\nيعني لوحدي مش هستحمل محدش هيبني بيا كوبري\nكده\nطب الـ carbon الصغير ده لو دخل بين الطبقات\nهيعمل إيه فكّروا\nبيقعد في المسافات الصغيرة فالطبقات\nمبتزحلقش والحديد يبقى أصلب بكتير\nده اسمه interstitial alloy وأشهر مثال عليه\nالـ steel يعني carbon جوه الحديد\nكده أقدر أشيل كوبري أنا والـ carbon فريق\nواحد\nوالحديد النقي ملوش أهمية صناعية عشان\nrelatively soft والـ alloys هي اللي بتشتغل\nوهو malleable و ductile و magnetic وبيدوب\nعند ألف خمسمية تمانية وتلاتين\nوأحيانا الحديد والـ carbon بيتحدوا\nكيميائيا ويطلع compound اسمه الـ cementite\nده\nده intermetallic alloy والـ formula بتاعته\nبتكسر قانون الـ valence خالص\nوفاكرين إن حجمنا تقريبا زي بعض ده بيخلّي\nذرات تانية تاخد مكان الحديد\nده substitutional alloy ذراته ليها نفس الـ\natomic radius والـ crystal lattice كمان\nزي الـ chromium في الـ stainless steel\nوالـ ferronickel والـ copper مع الدهب\nقبل ما يركبوني في الكوبري عملولي اختبارات\nكيميا كتير\nأول اختبار حطّوه في dilute sulphuric acid\nوهتلاقوا hydrogen طالع\nالملح اللي هيطلع iron two ولا iron three\nفكّروا\nأكيد تلاتة الـ half-filled ده أريح ليا\nلأ ملح iron two عشان الـ hydrogen بيعمل\nreduction للـ iron three على طول\nوالـ chromium اللي بيستخدموه في الـ\nplating metal نشيط بس الهوا مبيأثرش فيه\nعشان بيعمل طبقة oxide حجمها أكبر من الـ\nmetal nonporous بتقفل عليه\nوأنا كمان أقدر أعمل نفس الحيلة دي\nتاني اختبار الـ concentrated nitric acid\nعمل على الحديد طبقة oxide رفيعة بتحميه\nوده اسمه passivity والطبقة بتتشال بالحك أو\nبالـ dilute hydrochloric acid برضه\nوتالت اختبار سخّنوني لحد ما احمرّيت\nوجابولي هوا وبخار مية\nبيطلع الـ magnetic iron oxide ومع البخار\nبيطلع hydrogen كمان\nوللحديد تلات oxides الـ iron two oxide\nبودرة سودا\nوالـ iron three oxide اللي في الـ hematite\nوبيدخل في البويات الحمرا\nوالتالت الـ magnetite iron two oxide و\niron three oxide مع بعض\nونرجع للكوبري مع أول النهار ونجاوب السؤال\nالصخرة اتجهزت ore dressing وبعده roasting\nفي الهوا\nوفي الـ blast furnace الـ carbon monoxide\nشال الـ oxygen فرجع حديد\nوبالـ carbon بين الطبقات بقى steel والـ\nsteel شال الكوبري\nوكل ده من الأربعة اللي لوحدهم ولسه معايا\nلحد النهارده","countable":true,"series_id":"chem-s3-en.movie-ferro","episode_no":2,"episode_count":2},{"id":"chem-s3-en.question-phys.electric-charges-1","kind":"question","version":1,"ord":36,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"phys.electric-charges","concepts":[{"concept_id":"phys.electric-charges","role":"primary"}],"title":"chem-s3-en.question-phys.electric-charges-1","payload":{"stem":"The electrons of an atom stay around its nucleus instead of flying away. Which statement explains this?","tags":["diagnostic","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"The positive nucleus attracts the negative electrons.","correct":true},{"id":"b","text":"The negative nucleus attracts the negative electrons.","correct":false},{"id":"c","text":"The neutrons in the nucleus attract the electrons.","correct":false},{"id":"d","text":"The electrons attract each other and stay together.","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 pp.12-13 (nuclear attraction to electrons, atomic radius)","difficulty":1,"concept_ids":["phys.electric-charges"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! The protons make the nucleus positive. Unlike charges attract, so the nucleus pulls the negative electrons."},"b":{"why":"Electrons are negative, and a negative nucleus would push them away: like charges repel.","feedback":"Misconception: Like charges attract each other."},"c":{"why":"A neutron has no charge, so it cannot pull on an electron.","feedback":"Misconception: Neutrons carry an electric charge."},"d":{"why":"All electrons carry the same charge, and like charges repel each other.","feedback":"Misconception: Two electrons (like charges) attract each other."}},"explanation":"There are two kinds of charge: positive and negative. Like charges repel, and unlike charges attract. The nucleus contains protons (positive) and neutrons (no charge). Electrons are negative. So the positive nucleus attracts the negative electrons. The electrons themselves repel each other. You will use both ideas in this chapter: the nucleus attracts electrons, and electrons repel each other."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ protons هي اللي مخلية الـ nucleus positive. والـ unlike charges بتتجاذب، فالـ nucleus بتشد الـ electrons الـ negative."},"b":{"why":"الـ electrons negative، ولو الـ nucleus كانت negative كانت هتزقهم بعيد، لأن الـ like charges بتتنافر.","feedback":"الفكرة الغلط: إن الـ like charges بتتجاذب."},"c":{"why":"الـ neutron مالوش charge، فمايقدرش يشد electron.","feedback":"الفكرة الغلط: إن الـ neutrons شايلة electric charge."},"d":{"why":"الـ electrons كلها شايلة نفس الـ charge، والـ like charges بتتنافر، مش بتتجاذب.","feedback":"الفكرة الغلط: إن 2 electrons (يعني like charges) بيتجاذبوا."}},"explanation":"فيه نوعين من الـ charge: positive و negative. الـ like charges بتتنافر، والـ unlike charges بتتجاذب. الـ nucleus فيها protons (positive) و neutrons (مالهاش charge)، والـ electrons negative. عشان كده الـ nucleus الـ positive بتشد الـ electrons الـ negative. وفي نفس الوقت الـ electrons نفسها بتتنافر مع بعض. هتستخدم الفكرتين دول في الفصل ده: الـ nucleus بتجذب الـ electrons، والـ electrons بتتنافر مع بعض."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":22,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.electric-charges-2","kind":"question","version":1,"ord":37,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"phys.electric-charges","concepts":[{"concept_id":"phys.electric-charges","role":"primary"}],"title":"chem-s3-en.question-phys.electric-charges-2","payload":{"stem":"Two electrons are moved closer to each other. What happens to the force between them?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"They repel each other more strongly.","correct":true},{"id":"b","text":"They repel each other more weakly.","correct":false},{"id":"c","text":"They start to attract each other.","correct":false},{"id":"d","text":"There is no force, because they have the same charge.","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.13 (repulsion between 3d electrons, atomic radius)","difficulty":2,"concept_ids":["phys.electric-charges"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! Like charges repel, and the force gets stronger as the charges get closer."},"b":{"why":"You are right that they repel, but the force between charges is stronger when they are closer.","feedback":"Misconception: The force between charges gets weaker when they come closer."},"c":{"why":"Coming closer does not change the sign of a charge. Both are still negative, and like charges repel.","feedback":"Misconception: Charges that come close enough begin to attract, whatever their signs."},"d":{"why":"Charges of the same sign do act on each other: they push apart.","feedback":"Misconception: Like charges have no force between them; only unlike charges interact."}},"explanation":"Electrons are all negative, so two electrons are like charges and repel each other. The force between charges is stronger when they are closer. So moving the electrons closer makes the repulsion stronger. The book uses this idea: more electrons in 3d means more repulsion between them. This repulsion tends to increase the atomic radius."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ like charges بتتنافر، والـ force بتبقى أقوى لما الـ charges تقرب من بعض."},"b":{"why":"عندك حق إنهم بيتنافروا، لكن الـ force بين الـ charges بتبقى أقوى وهما قريبين، مش أضعف.","feedback":"الفكرة الغلط: إن الـ force بين الـ charges بتضعف لما يقربوا من بعض."},"c":{"why":"إنهم يقربوا مش بيغيّر إشارة الـ charge: الاتنين لسه negative، والـ like charges بتتنافر.","feedback":"الفكرة الغلط: إن الـ charges لو قربت من بعض كفاية بتبدأ تتجاذب، مهما كانت إشاراتها."},"d":{"why":"الـ charges اللي ليها نفس الإشارة بتأثر في بعض فعلًا: بتزق بعض بعيد.","feedback":"الفكرة الغلط: إن الـ like charges مفيش بينها force، وإن الـ unlike charges لوحدها هي اللي بتأثر في بعض."}},"explanation":"الـ electrons كلها negative، يعني 2 electrons هما like charges وبيتنافروا. والـ force بين الـ charges بتبقى أقوى لما يكونوا أقرب. عشان كده لما تقرّب الـ electrons من بعض، التنافر بيزيد. والكتاب بيستخدم الفكرة دي: electrons أكتر في الـ 3d يعني تنافر أكتر بينهم، والتنافر ده بيميل إنه يزوّد الـ atomic radius."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":23,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"beyond"}]},{"id":"chem-s3-en.question-sci.matter-particles-1","kind":"question","version":1,"ord":38,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"sci.matter-particles","concepts":[{"concept_id":"sci.matter-particles","role":"primary"}],"title":"chem-s3-en.question-sci.matter-particles-1","payload":{"stem":"Which statement about a piece of solid iron is correct?","tags":["diagnostic","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"It is made of tiny iron atoms that keep vibrating.","correct":true},{"id":"b","text":"It is one continuous piece with no particles inside.","correct":false},{"id":"c","text":"Its particles do not move at all because it is a solid.","correct":false},{"id":"d","text":"It is made of iron molecules, each built from different kinds of atoms.","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.13 (metals as solids made of atoms joined by a metallic bond)","difficulty":1,"concept_ids":["sci.matter-particles"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! A solid is made of particles too. In a solid they stay in place but keep vibrating."},"b":{"why":"It looks smooth, but every kind of matter is built from tiny particles.","feedback":"Misconception: Solids are continuous matter, not made of particles."},"c":{"why":"Particles in a solid are held in place, but they still vibrate.","feedback":"Misconception: Particles in a solid are completely still."},"d":{"why":"Iron is an element, and an element contains one kind of atom.","feedback":"Misconception: Every substance is made of molecules of different atoms, even an element."}},"explanation":"All matter is made of tiny particles. Iron is an element, so it is made of iron atoms only. In a solid, the atoms are packed close together and stay in place. They still keep moving: they vibrate. Later you will meet the metallic bond that holds the atoms of transition metals together."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ solid هو كمان معمول من particles. وفي الـ solid الـ particles بتفضل في مكانها لكنها بتفضل تهتز."},"b":{"why":"شكلها ناعم، لكن كل أنواع الـ matter معمولة من particles صغيرة جدًا.","feedback":"الفكرة الغلط: إن الـ solids مادة متصلة، مش معمولة من particles."},"c":{"why":"الـ particles اللي في الـ solid ثابتة في مكانها، لكنها لسه بتهتز.","feedback":"الفكرة الغلط: إن الـ particles اللي في الـ solid واقفة تمامًا."},"d":{"why":"الـ iron ده element، والـ element فيه نوع واحد من الـ atoms.","feedback":"الفكرة الغلط: إن أي substance معمولة من molecules فيها atoms مختلفة، حتى لو كانت element."}},"explanation":"الـ matter كلها معمولة من particles صغيرة جدًا. والـ iron ده element، يعني معمول من iron atoms تحديدًا. وفي الـ solid، الـ atoms بتبقى مرصوصة جنب بعض وثابتة في مكانها، ومع كده لسه بتتحرك: بتهتز. بعدين هتقابل الـ metallic bond اللي بيمسك الـ atoms بتاعة الـ transition metals ببعض."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":24,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"beyond"}]},{"id":"chem-s3-en.question-sci.matter-particles-2","kind":"question","version":1,"ord":39,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"sci.matter-particles","concepts":[{"concept_id":"sci.matter-particles","role":"primary"}],"title":"chem-s3-en.question-sci.matter-particles-2","payload":{"stem":"A copper rod gets slightly longer when it is heated. What happens to its atoms?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"They vibrate more, so the spaces between them get slightly bigger.","correct":true},{"id":"b","text":"Each atom grows bigger.","correct":false},{"id":"c","text":"New copper atoms are formed inside the rod.","correct":false},{"id":"d","text":"The atoms melt and spread out.","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.13 (atomic size and density of the first-series metals)","difficulty":2,"concept_ids":["sci.matter-particles"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! The atoms stay the same size. They move more and push a little further apart."},"b":{"why":"The rod grows, but each atom keeps the same size; the spaces between the atoms change.","feedback":"Misconception: Particles take on the properties of the whole object (atoms expand when the metal expands)."},"c":{"why":"Heating gives energy, not new matter: the number of atoms in the rod stays the same.","feedback":"Misconception: Heating creates new matter (new atoms)."},"d":{"why":"Melting is something the whole solid does; a single atom does not melt.","feedback":"Misconception: Single atoms have bulk properties such as melting."}},"explanation":"Heating gives the atoms more energy, so they vibrate more strongly. They push each other a little further apart. The spaces between atoms grow, so the whole rod gets longer. The atoms themselves keep the same size and number. Remember: a property of the whole metal (expanding, melting) is not a property of one atom."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ atoms حجمها بيفضل زي ما هو. اللي بيحصل إنها بتتحرك أكتر وبتزق بعضها لبعيد شوية."},"b":{"why":"القضيب بيطوّل، لكن كل atom بيفضل بنفس الحجم؛ اللي بيتغير هو المسافات اللي بين الـ atoms.","feedback":"الفكرة الغلط: إن الـ particles بتاخد خواص الجسم كله (الـ atoms بتتمدد لما الـ metal يتمدد)."},"c":{"why":"التسخين بيدي energy، مش matter جديدة: عدد الـ atoms في القضيب بيفضل زي ما هو.","feedback":"الفكرة الغلط: إن التسخين بيخلق matter جديدة (atoms جديدة)."},"d":{"why":"الـ melting حاجة بيعملها الـ solid كله؛ الـ atom الواحد مابيسيحش.","feedback":"الفكرة الغلط: إن الـ atom الواحد ليه خواص المادة ككل، زي إنه يسيح (melting)."}},"explanation":"التسخين بيدي الـ atoms energy أكتر، فبتهتز بقوة أكبر وبتزق بعضها لبعيد شوية. المسافات بين الـ atoms بتكبر، فالقضيب كله بيطوّل. إنما الـ atoms نفسها حجمها وعددها زي ما هما. افتكر: خاصية للـ metal كله (إنه يتمدد أو يسيح) مش خاصية لـ atom واحد."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":25,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.atomic-mass-number-1","kind":"question","version":1,"ord":40,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.atomic-mass-number","concepts":[{"concept_id":"atom.atomic-mass-number","role":"primary"}],"title":"chem-s3-en.question-atom.atomic-mass-number-1","payload":{"stem":"An iron atom is written as $^{56}_{26}\\mathrm{Fe}$. How many electrons does this neutral atom contain?","tags":["diagnostic","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"26","correct":true},{"id":"b","text":"56","correct":false},{"id":"c","text":"30","correct":false},{"id":"d","text":"82","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.8 (atomic numbers in the configuration table) and p.16 ($^{56}_{26}$Fe)","difficulty":1,"concept_ids":["atom.atomic-mass-number"],"est_seconds":35},"layer":{"choices":{"a":{"why":"Correct! The atomic number (26) is the number of protons. A neutral atom has the same number of electrons."},"b":{"why":"56 is the upper number. It counts protons and neutrons together, not electrons.","feedback":"Misconception: The mass number equals the number of electrons."},"c":{"why":"56 - 26 = 30 gives the neutrons. In a neutral atom, the electrons balance the protons' charge, so they match the protons.","feedback":"Misconception: Electrons = mass number - atomic number (confusing electrons with neutrons)."},"d":{"why":"Adding the two numbers does not count any particle. Each number tells you something on its own.","feedback":"Misconception: Add the atomic number and the mass number to get the electrons."}},"explanation":"In $^{A}_{Z}\\mathrm{X}$, Z (lower number) is the atomic number = number of protons. A (upper number) is the mass number = protons + neutrons. A neutral atom has as many electrons as protons. So iron has 26 protons and 26 electrons, and 56 - 26 = 30 neutrons. You need the number of electrons to write every electronic configuration in this chapter."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ atomic number (26) هو عدد الـ protons. والذرة المتعادلة فيها نفس العدد من الـ electrons."},"b":{"why":"الـ 56 ده الرقم اللي فوق، وبيعدّ الـ protons والـ neutrons مع بعض. الرقم اللي بيعدّ الـ protons لوحدها هو الرقم اللي تحت.","feedback":"الفكرة الغلط: إن الـ mass number بيساوي عدد الـ electrons."},"c":{"why":"56 - 26 = 30 ده عدد الـ neutrons. واللي بيعادل الـ charge بتاعة الـ protons في الذرة المتعادلة هو الـ electrons.","feedback":"الفكرة الغلط: إن الـ electrons = mass number - atomic number (لخبطة بين الـ electrons والـ neutrons)."},"d":{"why":"جمع الرقمين مش بيعدّ أي جسيم. الرقم اللي تحت هو عدد الـ protons، واللي فوق هو الـ protons والـ neutrons مع بعض.","feedback":"الفكرة الغلط: إنك تجمع الـ atomic number والـ mass number عشان تطلع الـ electrons."}},"explanation":"في $^{A}_{Z}\\mathrm{X}$، الـ Z (الرقم اللي تحت) هو الـ atomic number = عدد الـ protons. والـ A (الرقم اللي فوق) هو الـ mass number = protons + neutrons. الذرة المتعادلة فيها electrons بعدد الـ protons. يبقى الـ iron فيه 26 protons و26 electrons، و56 - 26 = 30 neutrons. وهتحتاج عدد الـ electrons عشان تكتب أي electronic configuration في الفصل ده."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":26,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.atomic-mass-number-2","kind":"question","version":1,"ord":41,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.atomic-mass-number","concepts":[{"concept_id":"atom.atomic-mass-number","role":"primary"}],"title":"chem-s3-en.question-atom.atomic-mass-number-2","payload":{"stem":"A cobalt atom has atomic number 27 and mass number 59. How many neutrons are in its nucleus?","tags":["diagnostic","calculate"],"type":"numeric","bloom":"apply","answer":{"unit":"neutrons","value":32,"tolerance":0},"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.12 (atomic mass of the first-series elements)","difficulty":2,"concept_ids":["atom.atomic-mass-number"],"est_seconds":45},"layer":{"explanation":"Mass number = protons + neutrons. Atomic number = protons = 27. Neutrons = mass number - atomic number = 59 - 27 = 32. Common wrong answers: 27 is the number of protons (and electrons). 59 counts protons and neutrons together. 86 comes from adding the two numbers. Key words: atomic number = number of protons; mass number = protons + neutrons."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ Mass number = protons + neutrons. والـ Atomic number = عدد الـ protons = 27. يبقى الـ neutrons = mass number - atomic number = 59 - 27 = 32. إجابات غلط بتتكرر: 27 ده عدد الـ protons (وكمان الـ electrons). 59 بيعدّ الـ protons والـ neutrons مع بعض. 86 جاية من إنك جمعت الرقمين. الكلمات المهمة: atomic number = عدد الـ protons؛ mass number = protons + neutrons."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":27,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.energy-levels-1","kind":"question","version":1,"ord":42,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.energy-levels","concepts":[{"concept_id":"atom.energy-levels","role":"primary"}],"title":"chem-s3-en.question-atom.energy-levels-1","payload":{"stem":"What is the greatest number of electrons the third main energy level (M, $n = 3$) can hold?","tags":["diagnostic","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"18","correct":true},{"id":"b","text":"8","correct":false},{"id":"c","text":"9","correct":false},{"id":"d","text":"6","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.8 (3d belongs to the third main energy level)","difficulty":1,"concept_ids":["atom.energy-levels"],"est_seconds":35},"layer":{"choices":{"a":{"why":"Correct! The maximum is $2n^2$. For $n = 3$ that is $2 \\times 3^2 = 18$."},"b":{"why":"8 is a common number for an outer level, but the full capacity of level $n = 3$ is $2n^2$.","feedback":"Misconception: Every main energy level holds at most 8 electrons."},"c":{"why":"You found $n^2$. That is the number of orbitals in the level, and each orbital holds 2 electrons.","feedback":"Misconception: Confusing the number of orbitals ($n^2$) with the number of electrons ($2n^2$)."},"d":{"why":"You doubled $n$, but the rule squares $n$ first: the capacity is $2n^2$, not $2n$.","feedback":"Misconception: Capacity of a level = $2n$."}},"explanation":"A main energy level $n$ holds at most $2n^2$ electrons. K ($n = 1$): 2. L ($n = 2$): 8. M ($n = 3$): 18. N ($n = 4$): 32. The M level can take 18 because it contains the 3d sublevel. This matters in this chapter: the first transition series fills the 3d sublevel, which is part of the third level."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! أقصى عدد هو $2n^2$، ولما $n = 3$ يبقى $2 \\times 3^2 = 18$."},"b":{"why":"8 رقم بيتكرر كتير في المستوى الخارجي، لكن السعة الكاملة للمستوى $n = 3$ من $2n^2$ أكبر من كده.","feedback":"الفكرة الغلط: إن كل main energy level أقصى ما يشيله 8 electrons."},"c":{"why":"إنت جبت $n^2$، وده عدد الـ orbitals في المستوى. والـ orbital الواحد بيساع 2 electrons، فالسعة ضعف الرقم ده.","feedback":"الفكرة الغلط: إنك تلخبط بين عدد الـ orbitals ($n^2$) وعدد الـ electrons ($2n^2$)."},"d":{"why":"إنت ضربت $n$ في 2، لكن القاعدة بتربّع $n$ الأول: السعة هي $2n^2$ مش $2n$.","feedback":"الفكرة الغلط: إن سعة المستوى = $2n$."}},"explanation":"الـ main energy level رقم $n$ أقصى ما يشيله $2n^2$ electrons: الـ K ($n = 1$): 2، الـ L ($n = 2$): 8، الـ M ($n = 3$): 18، الـ N ($n = 4$): 32. مستوى الـ M بيساع 18 عشان فيه الـ 3d sublevel. وده مهم في الفصل ده: الـ first transition series بتملا الـ 3d sublevel، واللي هو جزء من المستوى التالت."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":28,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.energy-levels-2","kind":"question","version":1,"ord":43,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.energy-levels","concepts":[{"concept_id":"atom.energy-levels","role":"primary"}],"title":"chem-s3-en.question-atom.energy-levels-2","payload":{"stem":"Which shows the correct distribution of the 20 electrons of calcium ($_{20}$Ca) in its main energy levels?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"2, 8, 8, 2","correct":true},{"id":"b","text":"2, 8, 10","correct":false},{"id":"c","text":"2, 18","correct":false},{"id":"d","text":"8, 8, 4","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.8 ($_{20}$Ca [Ar] 4s$^2$ comes just before the first transition series)","difficulty":2,"concept_ids":["atom.energy-levels"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Correct! Calcium starts the fourth level (N) before the third level (M) takes more than 8 electrons."},"b":{"why":"The M level can hold 18, but it does not fill to 18 first. The last two electrons of calcium go to the N level (4s).","feedback":"Misconception: Each level is filled to its maximum ($2n^2$) before the next level starts."},"c":{"why":"Level L ($n = 2$) holds at most 8 electrons, so it cannot take 18.","feedback":"Misconception: Level L can hold 18 electrons (wrong level capacities)."},"d":{"why":"Level K ($n = 1$) holds at most $2 \\times 1^2$ electrons, which is 2, so it cannot take 8.","feedback":"Misconception: Every level holds 8 electrons, including the first level (K)."}},"explanation":"Calcium has 20 electrons. K takes 2 and L takes 8. M takes 8 (3s and 3p). The last 2 go to the N level (4s), not to the 3d of level M. So the distribution is 2, 8, 8, 2. The book starts the first transition series right after calcium. From scandium on, the 3d sublevel of level M fills."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ calcium بيبدأ يحط electrons في المستوى الرابع (N) قبل ما المستوى التالت (M) ياخد أكتر من 8 electrons."},"b":{"why":"مستوى الـ M يقدر يشيل 18، لكنه مش بيتملي لحد 18 الأول. آخر اتنين electrons في الـ calcium بيروحوا لمستوى الـ N (الـ 4s).","feedback":"الفكرة الغلط: إن كل مستوى بيتملي لآخره ($2n^2$) قبل ما المستوى اللي بعده يبدأ."},"c":{"why":"مستوى الـ L ($n = 2$) أقصى ما يشيله 8 electrons، فالـ 18 في المستوى التاني مستحيل.","feedback":"الفكرة الغلط: إن مستوى الـ L يقدر يشيل 18 electrons (سعات المستويات متلخبطة)."},"d":{"why":"مستوى الـ K ($n = 1$) أقصى ما يشيله $2 \\times 1^2$ = 2 electrons، فالـ 8 في المستوى الأول مستحيل.","feedback":"الفكرة الغلط: إن كل مستوى بيشيل 8 electrons، حتى المستوى الأول (K)."}},"explanation":"الـ calcium فيه 20 electrons. الـ K بياخد 2، والـ L بياخد 8، والـ M بياخد 8 (في الـ 3s والـ 3p). آخر 2 بيروحوا لمستوى الـ N (الـ 4s)، مش للـ 3d اللي في مستوى الـ M. عشان كده التوزيع هو 2, 8, 8, 2. والكتاب بيبدأ الـ first transition series بعد الـ calcium على طول، ومن الـ scandium ورايح الـ 3d sublevel بتاع مستوى الـ M هو اللي بيتملي."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":29,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.elements-symbols-1","kind":"question","version":1,"ord":44,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"chem.elements-symbols","concepts":[{"concept_id":"chem.elements-symbols","role":"primary"}],"title":"chem-s3-en.question-chem.elements-symbols-1","payload":{"stem":"What is the chemical symbol of iron?","tags":["diagnostic","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"Fe","correct":true},{"id":"b","text":"I","correct":false},{"id":"c","text":"Ir","correct":false},{"id":"d","text":"F","correct":false}],"book_ref":"Prerequisite (earlier grades); used throughout Ch.1 (symbols of the first-series elements, p.5)","difficulty":1,"concept_ids":["chem.elements-symbols"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! Iron's symbol comes from its Latin name, ferrum."},"b":{"why":"I is the symbol of iodine. Some symbols come from Latin names, not English ones, and iron's Latin name is ferrum.","feedback":"Misconception: A symbol is always the first letter of the English name."},"c":{"why":"Ir is iridium, a different element. Not every symbol uses the first letters of the English name.","feedback":"Misconception: A symbol is always the first two letters of the English name."},"d":{"why":"F is fluorine, a gas. A two-letter symbol keeps both letters, and iron's symbol needs a second letter.","feedback":"Misconception: A symbol is only the first letter, even when the element needs two letters."}},"explanation":"Iron's symbol is Fe, from the Latin ferrum. Some other symbols in this chapter also come from Latin: copper is Cu (cuprum). A symbol has one capital letter, sometimes followed by one small letter. You will see Fe on almost every page of this chapter."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ symbol بتاع الـ iron جاي من اسمه اللاتيني، ferrum."},"b":{"why":"I ده symbol الـ iodine. وفيه symbols جاية من أسامي لاتيني مش إنجليزي، والـ iron منهم: اسمه اللاتيني ferrum.","feedback":"الفكرة الغلط: إن الـ symbol دايمًا هو أول حرف من الاسم الإنجليزي."},"c":{"why":"Ir ده الـ iridium، element تاني خالص. مش كل symbol بياخد أول حروف الاسم الإنجليزي.","feedback":"الفكرة الغلط: إن الـ symbol دايمًا هو أول حرفين من الاسم الإنجليزي."},"d":{"why":"F ده الـ fluorine، وده غاز. والـ symbol اللي من حرفين بيفضل بالحرفين، فالحرف الأول لوحده مش كفاية.","feedback":"الفكرة الغلط: إن الـ symbol هو أول حرف لوحده، حتى لو الـ element محتاج حرفين."}},"explanation":"الـ symbol بتاع الـ iron هو Fe، من الاسم اللاتيني ferrum. وفيه symbols تانية في الفصل ده جاية من اللاتيني برضه: الـ copper هو Cu (cuprum). الـ symbol فيه حرف كبير واحد، وساعات بييجي بعده حرف صغير واحد. هتشوف Fe تقريبًا في كل صفحة من الفصل ده."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":30,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series","section_title":"The First Transition Series","section_path":["Transition Elements","The First Transition Series"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.elements-symbols-2","kind":"question","version":2,"ord":45,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"chem.elements-symbols","concepts":[{"concept_id":"chem.elements-symbols","role":"primary"}],"title":"chem-s3-en.question-chem.elements-symbols-2","payload":{"stem":"Which formula represents an element (one kind of atom only), not a compound?","tags":["diagnostic","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"$\\ce{Co}$","correct":true},{"id":"b","text":"$\\ce{CO}$","correct":false},{"id":"c","text":"$\\ce{CuO}$","correct":false},{"id":"d","text":"$\\ce{Fe2O3}$","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.5 (cobalt, Co) and p.8 (oxides in the configuration table)","difficulty":2,"concept_ids":["chem.elements-symbols"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Co has one capital letter and one small letter, so it is one symbol: cobalt."},"b":{"why":"C and O are both capitals, so CO is two symbols: two elements, carbon and oxygen. That makes it a compound.","feedback":"Misconception: Two letters always form one symbol, even when both are capitals."},"c":{"why":"Cu is copper, but the capital O after it is a second symbol, oxygen. So CuO is a compound of copper and oxygen.","feedback":"Misconception: A formula that starts with a metal symbol is the metal element."},"d":{"why":"This is a compound of iron with oxygen, not iron itself: the formula shows two kinds of atoms.","feedback":"Misconception: A metal compound found in an ore is the metal element itself."}},"explanation":"An element is made of one kind of atom, so its formula has one symbol. Each symbol starts with a capital letter; a small letter belongs to the same symbol. Co (cobalt) is one symbol. CO is two symbols, C and O: carbon monoxide, a compound. CuO and $\\ce{Fe2O3}$ are compounds of a metal with oxygen. Read capitals carefully: Co and CO are very different."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! Co فيها حرف كبير واحد وحرف صغير واحد، يعني symbol واحد: الـ cobalt."},"b":{"why":"C و O الاتنين حروف كبيرة، يعني دول اتنين symbols، يعني اتنين elements، فده compound.","feedback":"الفكرة الغلط: إن أي حرفين دايمًا بيعملوا symbol واحد، حتى لو الاتنين كبار."},"c":{"why":"Cu ده الـ copper، لكن الـ O الكبيرة اللي بعده بتضيف element تاني للـ formula، فده compound.","feedback":"الفكرة الغلط: إن الـ formula اللي بتبدأ بـ symbol لـ metal تبقى هي الـ element بتاع الـ metal ده."},"d":{"why":"ده compound للـ iron من اللي بنلاقيه في الـ ore، مش الـ iron نفسه. الـ formula فيها نوعين من الذرات.","feedback":"الفكرة الغلط: إن الـ compound بتاع الـ metal اللي بنلاقيه في الـ ore هو الـ element نفسه."}},"explanation":"الـ element متكوّن من نوع واحد من الذرات، عشان كده الـ formula بتاعته فيها symbol واحد. كل symbol بيبدأ بحرف كبير، والحرف الصغير اللي بعده تبع نفس الـ symbol. Co (الـ cobalt) symbol واحد. أما CO فهي اتنين symbols، C و O: يعني carbon monoxide، وده compound. والـ CuO والـ $\\ce{Fe2O3}$ compounds من metal مع oxygen. خلّي بالك من الحروف الكبيرة: Co و CO مختلفين جدًا."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":31,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-pt.groups-periods-1","kind":"question","version":1,"ord":46,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"pt.groups-periods","concepts":[{"concept_id":"pt.groups-periods","role":"primary"}],"title":"chem-s3-en.question-pt.groups-periods-1","payload":{"stem":"Representative elements in the same group (vertical column) have similar chemical properties. Why?","tags":["diagnostic","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"They have the same number of electrons in the outer energy level.","correct":true},{"id":"b","text":"They have the same number of main energy levels.","correct":false},{"id":"c","text":"They have the same atomic mass.","correct":false},{"id":"d","text":"They have the same number of protons.","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.3 (group VIII elements resemble horizontally more than vertically)","difficulty":2,"concept_ids":["pt.groups-periods"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Chemical properties depend mainly on the outer electrons, and a group shares the same number."},"b":{"why":"Having the same number of levels describes a row (period), not a column.","feedback":"Misconception: Mixing up groups and periods (same number of levels = same group)."},"c":{"why":"Sodium and potassium have different masses. Chemical properties depend on the outer part of the atom, not on the mass.","feedback":"Misconception: Elements in a group have equal or similar atomic masses."},"d":{"why":"Two atoms with the same number of protons are the same element, so elements in a group cannot share it.","feedback":"Misconception: Elements in one group share the same atomic number."}},"explanation":"A period is a horizontal row. Its elements have the same number of main energy levels. A group is a vertical column. For the representative elements, a group shares the same number of outer electrons. Chemical properties depend mainly on outer electrons, so a group shares similar properties. In this chapter you will meet group VIII, where elements resemble their horizontal neighbours more. Keep the normal rule in mind first."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الخواص الكيميائية بتعتمد أساسًا على الـ outer electrons، وعناصر الـ group الواحد عندها نفس العدد منهم."},"b":{"why":"إن العناصر يبقى ليها نفس عدد المستويات ده وصف للصف الأفقي (period)، مش للعمود.","feedback":"الفكرة الغلط: إنك تلخبط بين الـ groups والـ periods (نفس عدد المستويات = نفس الـ group)."},"c":{"why":"الـ sodium والـ potassium كتلتهم مختلفة. الخواص الكيميائية بتعتمد على الجزء الخارجي من الذرة، مش على الكتلة.","feedback":"الفكرة الغلط: إن عناصر الـ group الواحد الـ atomic masses بتاعتها متساوية أو قريبة من بعض."},"d":{"why":"لو ذرتين ليهم نفس عدد الـ protons يبقوا نفس الـ element، فالعناصر اللي في group واحد مايقدروش يشتركوا فيه.","feedback":"الفكرة الغلط: إن عناصر الـ group الواحد ليها نفس الـ atomic number."}},"explanation":"الـ period صف أفقي، وعناصره ليها نفس عدد الـ main energy levels. والـ group عمود رأسي. في الـ representative elements، عناصر الـ group الواحد ليها نفس عدد الـ outer electrons. والخواص الكيميائية بتعتمد أساسًا على الـ outer electrons، عشان كده عناصر الـ group بتبقى خواصها متشابهة. في الفصل ده هتقابل group VIII، اللي عناصره بتشبه جيرانها اللي جنبها أفقيًا أكتر. لكن الأول ثبّت القاعدة العادية في دماغك."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":32,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te","section_title":"The transition elements","section_path":["Transition Elements","The transition elements"],"relation":"beyond"}]},{"id":"chem-s3-en.question-pt.groups-periods-2","kind":"question","version":1,"ord":47,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"pt.groups-periods","concepts":[{"concept_id":"pt.groups-periods","role":"primary"}],"title":"chem-s3-en.question-pt.groups-periods-2","payload":{"stem":"The electrons of potassium ($_{19}$K) are distributed as 2, 8, 8, 1. In which period is potassium?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"The fourth period","correct":true},{"id":"b","text":"The first period","correct":false},{"id":"c","text":"The third period","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.4 (the first transition series lies in the fourth period)","difficulty":2,"concept_ids":["pt.groups-periods"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Potassium's electrons occupy four main energy levels, so it is in period 4."},"b":{"why":"The 1 outer electron tells you the group. The period is the number of main levels that hold electrons.","feedback":"Misconception: Period number = number of outer electrons (mixing period with group)."},"c":{"why":"Don't stop at the third level: the period counts every level that holds electrons, including the outer one.","feedback":"Misconception: Period number = number of complete (full) energy levels."}},"explanation":"The period number equals the number of main energy levels that contain electrons. Potassium has electrons in K, L, M and N: four levels, so it is in the fourth period. Its single outer electron puts it in group 1 (IA). The first transition series is also in the fourth period, right after potassium and calcium."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ electrons بتاعة الـ potassium موجودة في أربع main energy levels، يبقى هو في period 4."},"b":{"why":"الـ outer electron الواحد بيقولك الـ group. إنما الـ period هو عدد المستويات الرئيسية اللي فيها electrons.","feedback":"الفكرة الغلط: إن رقم الـ period = عدد الـ outer electrons (لخبطة بين الـ period والـ group)."},"c":{"why":"متقفش عند المستوى التالت: الـ period بيعدّ كل مستوى فيه electrons، ومنهم المستوى الخارجي.","feedback":"الفكرة الغلط: إن رقم الـ period = عدد الـ energy levels الكاملة (المليانة)."}},"explanation":"رقم الـ period بيساوي عدد الـ main energy levels اللي فيها electrons. الـ potassium عنده electrons في K و L و M و N: أربع مستويات، يبقى هو في الـ period الرابع. والـ outer electron الواحد بتاعه بيحطه في group 1 (IA). والـ first transition series برضه في الـ period الرابع، بعد الـ potassium والـ calcium على طول."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":33,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.sublevels-1","kind":"question","version":1,"ord":48,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.sublevels","concepts":[{"concept_id":"atom.sublevels","role":"primary"}],"title":"chem-s3-en.question-atom.sublevels-1","payload":{"stem":"Which sublevels make up the third main energy level ($n = 3$)?","tags":["diagnostic","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"3s, 3p and 3d","correct":true},{"id":"b","text":"3s, 3p, 3d and 3f","correct":false},{"id":"c","text":"3s and 3p only","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.3 (the d sublevel) and p.4 (3d, 4d, 5d, 6d sublevels)","difficulty":1,"concept_ids":["atom.sublevels"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Level $n$ has $n$ sublevels, so level 3 has three: 3s, 3p and 3d."},"b":{"why":"Not every level has all four sublevels: level $n$ has $n$ sublevels, so there is no 3f.","feedback":"Misconception: Every main energy level has all four sublevels (s, p, d, f)."},"c":{"why":"3d exists, even though it fills after 4s. Level 3 has three sublevels.","feedback":"Misconception: There is no 3d sublevel, because d first appears in level 4."}},"explanation":"A main energy level $n$ contains $n$ sublevels. Level 1: 1s. Level 2: 2s, 2p. Level 3: 3s, 3p, 3d. Level 4: 4s, 4p, 4d, 4f. So the d sublevel first appears at $n = 3$. The 3d sublevel is the one filled in the first transition series."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! المستوى $n$ فيه $n$ من الـ sublevels، يعني المستوى 3 فيه تلاتة: 3s و3p و3d."},"b":{"why":"مش كل مستوى فيه الـ sublevels الأربعة. المستوى $n$ فيه $n$ من الـ sublevels، فالـ 3f مش موجود.","feedback":"الفكرة الغلط: إن كل main energy level فيه الـ sublevels الأربعة (s, p, d, f)."},"c":{"why":"الـ 3d موجود، حتى لو بيتملي بعد الـ 4s. المستوى 3 فيه 3 sublevels.","feedback":"الفكرة الغلط: إن مفيش 3d sublevel، عشان الـ d أول ما بيظهر بيظهر في المستوى 4."}},"explanation":"الـ main energy level رقم $n$ بيبقى فيه $n$ من الـ sublevels. المستوى 1: 1s. المستوى 2: 2s و2p. المستوى 3: 3s و3p و3d. المستوى 4: 4s و4p و4d و4f. يعني الـ d sublevel أول ما بيظهر بيظهر عند $n = 3$. والـ 3d sublevel ده هو اللي بيتملي في الـ first transition series."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":34,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.sublevels-2","kind":"question","version":1,"ord":49,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.sublevels","concepts":[{"concept_id":"atom.sublevels","role":"primary"}],"title":"chem-s3-en.question-atom.sublevels-2","payload":{"stem":"Which of the following sublevels cannot exist?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"2d","correct":true},{"id":"b","text":"3d","correct":false},{"id":"c","text":"4f","correct":false},{"id":"d","text":"5d","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.4 (series fill 3d, 4d, 5d, 6d)","difficulty":2,"concept_ids":["atom.sublevels"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! Level 2 has only two sublevels, 2s and 2p. There is no 2d."},"b":{"why":"3d fills after 4s, but it still exists: level 3 has three sublevels, 3s, 3p and 3d.","feedback":"Misconception: There is no 3d sublevel, because d first appears in level 4."},"c":{"why":"Level 4 has four sublevels: 4s, 4p, 4d and 4f. So 4f exists.","feedback":"Misconception: The f sublevel only appears in level 5 or higher."},"d":{"why":"Level 5 has at least four sublevels, s, p, d and f, so 5d exists.","feedback":"Misconception: A d sublevel belongs only to levels 3 and 4."}},"explanation":"Level $n$ has $n$ sublevels: level 2 has s and p only, so 2d cannot exist. 3d exists in level 3, 4f in level 4, and 5d in level 5. The transition series use 3d, 4d, 5d and 6d. They never use 1d or 2d."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! المستوى 2 فيه 2 sublevels تحديدًا: 2s و2p. يعني مفيش 2d."},"b":{"why":"الـ 3d بيتملي بعد الـ 4s، لكن ده مش معناه إنه مش موجود. المستوى 3 فيه 3 sublevels، والـ d واحد منهم.","feedback":"الفكرة الغلط: إن مفيش 3d sublevel، عشان الـ d أول ما بيظهر بيظهر في المستوى 4."},"c":{"why":"المستوى 4 فيه 4 sublevels: s و p و d و f، فالـ 4f موجود.","feedback":"الفكرة الغلط: إن الـ f sublevel مابيظهرش غير في المستوى 5 أو أعلى."},"d":{"why":"المستوى 5 فيه 4 sublevels على الأقل، والـ d من ضمن أول أربعة، فالـ 5d موجود.","feedback":"الفكرة الغلط: إن الـ d sublevel موجود في المستويين 3 و4 تحديدًا."}},"explanation":"المستوى $n$ فيه $n$ من الـ sublevels: المستوى 2 فيه s و p وخلاص، فالـ 2d مايمكنش يكون موجود. الـ 3d موجود في المستوى 3، والـ 4f في المستوى 4، والـ 5d في المستوى 5. والـ transition series بتستخدم 3d و4d و5d و6d، وعمرها ما بتستخدم 1d أو 2d."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":35,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.orbitals-1","kind":"question","version":1,"ord":50,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.orbitals","concepts":[{"concept_id":"atom.orbitals","role":"primary"}],"title":"chem-s3-en.question-atom.orbitals-1","payload":{"stem":"How many orbitals are there in a d sublevel?","tags":["diagnostic","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"5","correct":true},{"id":"b","text":"10","correct":false},{"id":"c","text":"3","correct":false},{"id":"d","text":"7","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.8 (five 3d orbitals filled by Hund's rule)","difficulty":1,"concept_ids":["atom.orbitals"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! A d sublevel has 5 orbitals. With 2 electrons in each, it holds 10 electrons."},"b":{"why":"10 is the number of electrons a d sublevel can hold. One orbital holds 2 electrons, so the number of orbitals is smaller.","feedback":"Misconception: Confusing the number of orbitals with the number of electrons."},"c":{"why":"3 orbitals belong to a p sublevel, not to a d sublevel.","feedback":"Misconception: Mixing up the orbitals of p and d sublevels."},"d":{"why":"7 orbitals belong to an f sublevel, not to a d sublevel.","feedback":"Misconception: Mixing up the orbitals of d and f sublevels."}},"explanation":"Number of orbitals: s = 1, p = 3, d = 5, f = 7. Each orbital holds at most 2 electrons. So a d sublevel holds $5 \\times 2 = 10$ electrons. You will draw these five d orbitals as five boxes in this chapter."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ d sublevel فيه 5 orbitals. ولو في كل واحد 2 electrons، يبقى بيشيل 10 electrons."},"b":{"why":"الـ 10 دي عدد الـ electrons اللي الـ d sublevel يقدر يشيلها، والـ orbital الواحد بياخد 2 electrons، فعدد الـ orbitals نص الرقم ده.","feedback":"الفكرة الغلط: إنك تلخبط بين عدد الـ orbitals وعدد الـ electrons."},"c":{"why":"الـ 3 orbitals دول بتوع الـ p sublevel، مش الـ d sublevel.","feedback":"الفكرة الغلط: إنك تلخبط بين orbitals الـ p sublevel والـ d sublevel."},"d":{"why":"الـ 7 orbitals دول بتوع الـ f sublevel، مش الـ d sublevel.","feedback":"الفكرة الغلط: إنك تلخبط بين orbitals الـ d sublevel والـ f sublevel."}},"explanation":"عدد الـ orbitals: s = 1، p = 3، d = 5، f = 7. والـ orbital الواحد بيشيل 2 electrons على الأكتر. يبقى الـ d sublevel بيشيل $5 \\times 2 = 10$ electrons. وفي الفصل ده هترسم الـ 5 d orbitals دول على شكل 5 مربعات."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":36,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-atom.orbitals-2","kind":"question","version":1,"ord":51,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.orbitals","concepts":[{"concept_id":"atom.orbitals","role":"primary"}],"title":"chem-s3-en.question-atom.orbitals-2","payload":{"stem":"Which statement describes an orbital correctly?","tags":["diagnostic","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"A region around the nucleus where an electron is most likely found; it holds up to 2 electrons.","correct":true},{"id":"b","text":"A fixed circular path around the nucleus; it holds up to 2 electrons.","correct":false,"misconception_id":"atom.orbitals.mc1"},{"id":"c","text":"A region around the nucleus where an electron is most likely found; it holds up to 8 electrons.","correct":false},{"id":"d","text":"A fixed circular path around the nucleus; it holds up to 8 electrons.","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 pp.8, 13 (orbitals drawn as boxes holding ↑ or ↑↓)","difficulty":2,"concept_ids":["atom.orbitals"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! An orbital is a region in space, not a track, and it takes at most 2 electrons."},"b":{"why":"The number is right. But the electron does not move on a fixed circle; it is found in a region.","feedback":"Misconception: An orbital is a circular path (orbit) of the electron."},"c":{"why":"The region idea is right. But 8 is a level's outer capacity: one orbital holds at most 2 electrons.","feedback":"Misconception: An orbital holds up to 8 electrons (octet)."},"d":{"why":"Two ideas need fixing here: an orbital is a region, not a path, and it holds at most 2 electrons, not 8.","feedback":"Misconception: An orbital is a circular path holding 8 electrons (orbital confused with a main energy level)."}},"explanation":"An orbital is a region of space around the nucleus where the electron is most likely to be found. It is not a circular path. Each orbital holds at most 2 electrons, with opposite spins. In the book, each orbital is drawn as a box: ↑ for one electron, ↑↓ for two."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ orbital منطقة في الفراغ، مش مسار، وبياخد 2 electrons على الأكتر."},"b":{"why":"الرقم صح، لكن الـ electron مش بيتحرك على دايرة ثابتة؛ هو بيتلاقى في منطقة.","feedback":"الفكرة الغلط: إن الـ orbital مسار دايري (orbit) بيلف فيه الـ electron."},"c":{"why":"فكرة المنطقة صح، لكن الـ 8 دي سعة المستوى الخارجي، والـ orbital الواحد بياخد 2 electrons بالكتير.","feedback":"الفكرة الغلط: إن الـ orbital بيشيل لحد 8 electrons (octet)."},"d":{"why":"فيه هنا فكرتين غلط: الـ orbital مش مسار، هو منطقة، وبيشيل 2 electrons بالكتير، مش 8.","feedback":"الفكرة الغلط: إن الـ orbital مسار دايري بيشيل 8 electrons (لخبطة بين الـ orbital والـ main energy level)."}},"explanation":"الـ orbital هو منطقة في الفراغ حوالين الـ nucleus، احتمال وجود الـ electron فيها أكبر ما يمكن. مش مسار دايري. والـ orbital الواحد بيشيل 2 electrons على الأكتر، والاتنين بيبقى ليهم opposite spins. وفي الكتاب الـ orbital بيترسم مربع: ↑ لـ electron واحد، و↑↓ لاتنين."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":37,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.aufbau-1","kind":"question","version":1,"ord":52,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.aufbau","concepts":[{"concept_id":"atom.aufbau","role":"primary"}],"title":"chem-s3-en.question-atom.aufbau-1","payload":{"stem":"Arrange these sublevels in the order in which electrons fill them (Aufbau principle), first to last.","tags":["diagnostic","arrange"],"type":"order","bloom":"understand","answer":["s3","p3","s4","d3","p4"],"choices":[{"id":"p4","text":"4p"},{"id":"d3","text":"3d"},{"id":"s3","text":"3s"},{"id":"s4","text":"4s"},{"id":"p3","text":"3p"}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.8 (after Ca [Ar] 4s$^2$, the 3d sublevel fills)","difficulty":2,"concept_ids":["atom.aufbau"],"est_seconds":60},"layer":{"choices":{"d3":{"why":"The level number alone does not decide the filling order: 3d fills after 4s, not right after 3p. That is why calcium ends with 4s and the first transition series then fills 3d."},"p3":{"why":"3p comes second: it fills right after 3s and before 4s in the order 1s, 2s, 2p, 3s, 3p, 4s, ..."},"p4":{"why":"Sublevels of the same level do not always fill one right after another: 4p comes after 3d, not right after 4s."},"s3":{"why":"3s comes first here: in the filling order 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, it fills before every other sublevel in this list."},"s4":{"why":"A bigger level number does not always mean a later sublevel: 4s fills before 3d, right after 3p."}},"explanation":"By the Aufbau principle, electrons fill sublevels in this order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, ... So the order here is 3s, 3p, 4s, 3d, 4p. Most common mistake: putting 3d right after 3p because 3 comes before 4. This order explains why calcium ends with 4s², and the first transition series then fills 3d."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"d3":{"why":"رقم المستوى لوحده مش هو اللي بيحدد ترتيب الملء: الـ 3d بتتملي بعد الـ 4s، مش على طول بعد الـ 3p. وده اللي بيفسر ليه الـ calcium بينتهي بـ 4s وبعده الـ first transition series بتملا الـ 3d."},"p3":{"why":"الـ 3p هي التانية: بتتملي على طول بعد الـ 3s وقبل الـ 4s في الترتيب 1s, 2s, 2p, 3s, 3p, 4s, ..."},"p4":{"why":"الـ sublevels اللي في نفس المستوى مش لازم تتملي ورا بعض على طول: الـ 4p بتيجي بعد الـ 3d، مش على طول بعد الـ 4s."},"s3":{"why":"الـ 3s هي الأولى هنا: في ترتيب الملء 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p بتتملي قبل باقي الـ sublevels اللي في القايمة دي."},"s4":{"why":"رقم مستوى أكبر مش معناه على طول sublevel بييجي متأخر: الـ 4s بتتملي قبل الـ 3d، على طول بعد الـ 3p."}},"explanation":"حسب الـ Aufbau principle، الـ electrons بتملا الـ sublevels بالترتيب ده: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, ... يبقى الترتيب هنا: 3s, 3p, 4s, 3d, 4p. أشهر غلطة: إنك تحط الـ 3d على طول بعد الـ 3p عشان 3 قبل 4. الترتيب ده هو اللي بيفسر ليه الـ calcium بينتهي بـ 4s²، وبعده الـ first transition series بتملا الـ 3d."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":38,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.aufbau-2","kind":"question","version":1,"ord":53,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.aufbau","concepts":[{"concept_id":"atom.aufbau","role":"primary"}],"title":"chem-s3-en.question-atom.aufbau-2","payload":{"stem":"Argon ($_{18}$Ar) has the configuration $1s^2\\,2s^2\\,2p^6\\,3s^2\\,3p^6$. Which sublevel receives the 19th electron in potassium ($_{19}$K)?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"4s","correct":true},{"id":"b","text":"3d","correct":false},{"id":"c","text":"4p","correct":false},{"id":"d","text":"3p","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.8 (filling of 4s before 3d)","difficulty":2,"concept_ids":["atom.aufbau"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! After 3p, the next sublevel in the Aufbau order is 4s."},"b":{"why":"3d belongs to level 3, but that is not what decides the order. In the Aufbau order, 4s comes right after 3p, before 3d.","feedback":"Misconception: 3d fills before 4s because 3 < 4."},"c":{"why":"Level 4 does start here, but 4p fills after 4s and 3d, not right after 3p.","feedback":"Misconception: A new level starts with its p sublevel."},"d":{"why":"Argon's 3p already holds 6 electrons, and a p sublevel cannot take more than that.","feedback":"Misconception: A p sublevel can hold more than 6 electrons."}},"explanation":"3p is full at argon ($3p^6$). By the Aufbau principle, the order after 3p is 4s, then 3d, then 4p. So the 19th electron goes into 4s: K is $[\\mathrm{Ar}]\\,4s^1$. Remember this order: 3d starts filling only after 4s, from scandium onwards."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! بعد الـ 3p، الـ sublevel اللي عليه الدور في ترتيب الـ Aufbau هو الـ 4s."},"b":{"why":"الـ 3d تبع المستوى 3، لكن ده مش اللي بيحدد الترتيب. في ترتيب الـ Aufbau، الـ 3d مش بييجي بعد الـ 3p على طول؛ فيه sublevel من المستوى 4 بيتملي قبله.","feedback":"الفكرة الغلط: إن الـ 3d بيتملي قبل الـ 4s عشان 3 < 4."},"c":{"why":"فعلًا المستوى 4 بيبدأ هنا، لكن الـ 4p بييجي بعد الـ 3d في ترتيب الـ Aufbau، فمش هو اللي بيفتح المستوى الجديد.","feedback":"الفكرة الغلط: إن المستوى الجديد بيبدأ بالـ p sublevel بتاعه."},"d":{"why":"الـ 3p بتاع الـ argon فيه 6 electrons، والـ p sublevel مايشيلش أكتر من 6، فهو مليان خلاص.","feedback":"الفكرة الغلط: إن الـ p sublevel يقدر يشيل أكتر من 6 electrons."}},"explanation":"الـ 3p بيتملي على الآخر عند الـ argon ($3p^6$). وحسب الـ Aufbau principle، الترتيب بعد الـ 3p هو 4s وبعدين 3d وبعدين 4p. يبقى الـ electron رقم 19 بيروح للـ 4s: الـ K هو $[\\mathrm{Ar}]\\,4s^1$. افتكر الترتيب ده: الـ 3d مش بيبدأ يتملي غير بعد الـ 4s، من أول الـ scandium."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":39,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.magnetic-field-1","kind":"question","version":1,"ord":54,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"phys.magnetic-field","concepts":[{"concept_id":"phys.magnetic-field","role":"primary"}],"title":"chem-s3-en.question-phys.magnetic-field-1","payload":{"stem":"An ordinary bar magnet is brought near each object. Which object is clearly pulled toward it?","tags":["diagnostic","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"An iron nail","correct":true},{"id":"b","text":"A copper wire","correct":false,"misconception_id":"phys.magnetic-field.mc1"},{"id":"c","text":"A plastic ruler rubbed with a cloth","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 pp.13-14 (attraction to an external magnetic field) and p.6 (Fe and Co can be magnetized)","difficulty":1,"concept_ids":["phys.magnetic-field"],"est_seconds":35},"layer":{"choices":{"a":{"why":"Correct! Iron is one of the few materials a magnet pulls strongly."},"b":{"why":"Copper is a metal, but a magnet does not clearly pull most metals; a copper coin is not pulled by a fridge magnet.","feedback":"Misconception: Magnets attract all metals."},"c":{"why":"Rubbing gives the ruler an electric charge, and an electric charge is electricity, not magnetism.","feedback":"Misconception: Electric charge and magnetism are the same thing."}},"explanation":"A magnet has a magnetic field around it. It strongly attracts some materials, like iron, cobalt and nickel. Most metals, such as copper, are not clearly pulled. A rubbed ruler is charged; that is electricity, not magnetism. In this chapter you will see that some substances are only weakly attracted to an external magnetic field."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ iron من المواد القليلة اللي الـ magnet بيشدها بقوة."},"b":{"why":"الـ copper فعلًا metal، لكن الـ magnet مش بيشد معظم الـ metals بشكل واضح؛ عملة copper مش بتتشد لـ magnet التلاجة.","feedback":"الفكرة الغلط: إن الـ magnet بيجذب كل الـ metals."},"c":{"why":"الدعك بيدي المسطرة electric charge، والـ electric charge دي كهربا، مش magnetism.","feedback":"الفكرة الغلط: إن الـ electric charge والـ magnetism حاجة واحدة."}},"explanation":"الـ magnet حواليه magnetic field. وبيجذب بقوة مواد معيّنة، زي الـ iron والـ cobalt والـ nickel. أغلب الـ metals، زي الـ copper، مش بتتشد بشكل واضح. والمسطرة المدعوكة عليها charge؛ وده كهربا، مش magnetism. وفي الفصل ده هتشوف إن فيه مواد بتنجذب للـ external magnetic field انجذاب ضعيف مش أكتر."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":40,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.magnetic-field-2","kind":"question","version":1,"ord":55,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"phys.magnetic-field","concepts":[{"concept_id":"phys.magnetic-field","role":"primary"}],"title":"chem-s3-en.question-phys.magnetic-field-2","payload":{"stem":"The south pole of magnet A attracts end X of magnet B. What is end X?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"A north pole","correct":true},{"id":"b","text":"A south pole","correct":false},{"id":"c","text":"It could be either pole, because a magnet attracts both","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 pp.13-14 (substances attracted to or repelled by an external magnetic field)","difficulty":2,"concept_ids":["phys.magnetic-field"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Unlike poles attract, so the end attracted to a south pole is a north pole."},"b":{"why":"Two magnets with the same poles facing push apart: like poles repel.","feedback":"Misconception: Like poles attract each other."},"c":{"why":"One pole of a magnet does not attract both poles of another: like poles repel.","feedback":"Misconception: A magnet always attracts, whatever the pole."}},"explanation":"Every magnet has a north and a south pole. Like poles repel, and unlike poles attract. End X is attracted to a south pole, so it must be a north pole. So a magnetic field can attract or repel. In this chapter, paramagnetic substances are attracted to an external field and diamagnetic ones are repelled."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ unlike poles بتتجاذب، فالطرف اللي بينجذب لـ south pole يبقى north pole."},"b":{"why":"2 magnets قصاد بعض بنفس الـ poles بيزقّوا بعض: الـ like poles بتتنافر.","feedback":"الفكرة الغلط: إن الـ like poles بتتجاذب."},"c":{"why":"الـ pole الواحد في الـ magnet مش بيجذب الـ poles الاتنين بتوع magnet تاني: الـ like poles بتتنافر.","feedback":"الفكرة الغلط: إن الـ magnet دايمًا بيجذب، مهما كان الـ pole."}},"explanation":"أي magnet ليه north pole و south pole. الـ like poles بتتنافر، والـ unlike poles بتتجاذب. الطرف X بينجذب لـ south pole، يبقى لازم يكون north pole. يعني الـ magnetic field ممكن يجذب وممكن يطرد. وفي الفصل ده، الـ paramagnetic substances بتنجذب للـ external field، والـ diamagnetic بتتنافر معاه."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":41,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.electron-spin-pauli-1","kind":"question","version":1,"ord":56,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.electron-spin-pauli","concepts":[{"concept_id":"atom.electron-spin-pauli","role":"primary"}],"title":"chem-s3-en.question-atom.electron-spin-pauli-1","payload":{"stem":"Two electrons occupy the same orbital. Which statement is correct?","tags":["diagnostic","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"They spin in opposite directions, so their magnetic effects cancel.","correct":true},{"id":"b","text":"They spin in the same direction, so their magnetic effects add up.","correct":false},{"id":"c","text":"They stop spinning, because the orbital is full.","correct":false},{"id":"d","text":"They spin in opposite directions, so their magnetic effects add up.","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.14 (paired electrons: magnetic moment zero due to opposite spin)","difficulty":2,"concept_ids":["atom.electron-spin-pauli"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! The Pauli principle forces opposite spins, and opposite spins cancel each other's magnetic effect."},"b":{"why":"Two electrons in one orbital cannot be identical: their spins must be opposite.","feedback":"Misconception: Two electrons in one orbital can have the same spin (Pauli principle ignored)."},"c":{"why":"Electrons keep spinning in a full orbital; the two spins point in opposite directions.","feedback":"Misconception: Paired electrons stop spinning."},"d":{"why":"The spins are right. But two tiny magnets pointing opposite ways cancel each other's effect; they do not add up.","feedback":"Misconception: Opposite spins double the magnetic effect."}},"explanation":"Each electron spins and acts like a tiny magnet. By the Pauli principle, two electrons in one orbital must have opposite spins (↑↓). Opposite spins cancel each other's magnetic effect. The book uses this idea: when all electrons are paired, the magnetic moment equals zero (diamagnetic)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ Pauli principle بيفرض إن الـ spins تبقى opposite، والـ opposite spins بتلغي التأثير المغناطيسي لبعض."},"b":{"why":"حسب الـ Pauli principle، الـ orbital الواحد بيشيل اتنين electrons بشرط إن الـ spins بتوعهم تبقى opposite، مش في نفس الاتجاه.","feedback":"الفكرة الغلط: إن اتنين electrons في orbital واحد ممكن يبقى ليهم نفس الـ spin (تجاهل للـ Pauli principle)."},"c":{"why":"الـ electrons بتفضل تعمل spin حتى لو الـ orbital مليان، والـ spins الاتنين بيبقوا في اتجاهين عكس بعض.","feedback":"الفكرة الغلط: إن الـ electrons اللي في زوج بتبطّل spin."},"d":{"why":"الـ spins كده مظبوطة، لكن مغناطيسين صغيرين متوجّهين عكس بعض تأثيرهم بيلغي بعضه، مش بيتجمع.","feedback":"الفكرة الغلط: إن الـ opposite spins بتضاعف التأثير المغناطيسي."}},"explanation":"كل electron بيعمل spin وبيتصرّف كأنه مغناطيس صغير. وحسب الـ Pauli principle، اتنين electrons في orbital واحد لازم يكون ليهم opposite spins (↑↓). والـ opposite spins بتلغي التأثير المغناطيسي لبعض. الكتاب بيستخدم الفكرة دي: لما الـ electrons كلها تبقى أزواج، الـ magnetic moment بيساوي صفر (diamagnetic)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":42,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"}]},{"id":"chem-s3-en.question-atom.electron-spin-pauli-2","kind":"question","version":1,"ord":57,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.electron-spin-pauli","concepts":[{"concept_id":"atom.electron-spin-pauli","role":"primary"}],"title":"chem-s3-en.question-atom.electron-spin-pauli-2","payload":{"stem":"What is the greatest number of electrons in one d sublevel that can all spin in the same direction?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"5","correct":true},{"id":"b","text":"10","correct":false},{"id":"c","text":"2","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.8 (3d orbitals filled by single electrons up to $3d^5$)","difficulty":2,"concept_ids":["atom.electron-spin-pauli"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Correct! Each of the 5 d orbitals can hold only one electron of a given spin. So at most 5 can be parallel."},"b":{"why":"A d sublevel holds 10 electrons, but two electrons in the same orbital cannot spin the same way.","feedback":"Misconception: All electrons of a sublevel can have the same spin (Pauli principle ignored)."},"c":{"why":"Two is the number of electrons in one orbital, and those two spin oppositely, so electrons with the same spin must be in different orbitals.","feedback":"Misconception: Parallel spins mean two electrons sharing one orbital."}},"explanation":"A d sublevel has 5 orbitals. By the Pauli principle, an orbital can hold two electrons only with opposite spins. So each orbital can give at most one electron spinning ↑. With 5 orbitals, at most 5 electrons can spin the same way. That is why a $d^5$ sublevel has 5 unpaired electrons, the greatest possible number."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! كل orbital من الـ 5 d orbitals مايشيلش أكتر من electron واحد بـ spin معيّن. يعني أقصى عدد يكونوا parallel هو 5."},"b":{"why":"الـ d sublevel بيشيل 10 electrons، لكن اتنين electrons في نفس الـ orbital لازم يبقى ليهم opposite spins، فمش العشرة هيبقوا في نفس الاتجاه.","feedback":"الفكرة الغلط: إن كل الـ electrons اللي في الـ sublevel ممكن يبقى ليها نفس الـ spin (تجاهل للـ Pauli principle)."},"c":{"why":"2 ده عدد الـ electrons في orbital واحد، والاتنين دول بيعملوا spin عكس بعض، فمش parallel. الـ parallel spins بتيجي من electron واحد في كل orbital من الـ 5 d orbitals.","feedback":"الفكرة الغلط: إن الـ parallel spins معناها اتنين electrons في orbital واحد."}},"explanation":"الـ d sublevel فيه 5 orbitals. وحسب الـ Pauli principle، الـ orbital يشيل اتنين electrons بشرط إن الـ spins تبقى opposite. يعني كل orbital يقدر يدّي electron واحد بالكتير بيعمل spin ↑. ومع 5 orbitals، أقصى عدد electrons يعملوا spin في نفس الاتجاه هو 5. وعشان كده الـ $d^5$ sublevel فيه 5 unpaired electrons، وده أكبر عدد ممكن."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":43,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-atom.electron-configuration-writing-1","kind":"question","version":1,"ord":58,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.electron-configuration-writing","concepts":[{"concept_id":"atom.electron-configuration-writing","role":"primary"}],"title":"chem-s3-en.question-atom.electron-configuration-writing-1","payload":{"stem":"Which is the correct electronic configuration of calcium ($_{20}$Ca)?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$1s^2\\,2s^2\\,2p^6\\,3s^2\\,3p^6\\,4s^2$","correct":true},{"id":"b","text":"$1s^2\\,2s^2\\,2p^6\\,3s^2\\,3p^6\\,3d^2$","correct":false},{"id":"c","text":"$1s^2\\,2s^2\\,2p^6\\,3s^2\\,3p^8$","correct":false},{"id":"d","text":"$1s^2\\,2s^2\\,2p^6\\,3s^2\\,3p^6\\,3d^1\\,4s^1$","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.8 (configuration table; $_{20}$Ca [Ar] 4s$^2$)","difficulty":2,"concept_ids":["atom.electron-configuration-writing"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Correct! 2 + 2 + 6 + 2 + 6 + 2 = 20, filled in the Aufbau order."},"b":{"why":"The count is 20, but the order is wrong: 4s fills right after 3p, before 3d.","feedback":"Misconception: 3d fills before 4s because 3 < 4."},"c":{"why":"A p sublevel has 3 orbitals with 2 electrons in each, so it holds at most 6 electrons, not the 8 in $3p^8$.","feedback":"Misconception: A p sublevel can hold 8 electrons."},"d":{"why":"Electrons do not spread over sublevels by choice. 4s must be full before 3d starts.","feedback":"Misconception: Electrons are shared between 4s and 3d to balance them."}},"explanation":"Fill in the Aufbau order. Respect each capacity: s = 2, p = 6, d = 10. $1s^2\\,2s^2\\,2p^6\\,3s^2\\,3p^6$ uses 18 electrons. The last 2 go to 4s. Short form: $[\\mathrm{Ar}]\\,4s^2$. This is exactly where the book starts the first transition series: after calcium, 3d begins to fill."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! 2 + 2 + 6 + 2 + 6 + 2 = 20، ومتملّيين بترتيب الـ Aufbau."},"b":{"why":"العدد 20 مظبوط، لكن الترتيب غلط: الـ 3d مش بيتملي بعد الـ 3p على طول؛ الـ 4s بييجي قبله.","feedback":"الفكرة الغلط: إن الـ 3d بيتملي قبل الـ 4s عشان 3 < 4."},"c":{"why":"الـ p sublevel فيه 3 orbitals، وكل orbital بيساع 2 electrons، يعني الـ p بيشيل 6 بالكتير، و$3p^8$ مستحيل.","feedback":"الفكرة الغلط: إن الـ p sublevel ممكن يشيل 8 electrons."},"d":{"why":"الـ electrons مابتتوزعش على الـ sublevels على مزاجها. في الـ Ca، الـ 4s لازم يتملى قبل ما الـ 3d يبدأ.","feedback":"الفكرة الغلط: إن الـ electrons بتتقسم بين الـ 4s والـ 3d عشان يبقوا متوازنين."}},"explanation":"املا بترتيب الـ Aufbau، واحترم سعة كل sublevel: s = 2، p = 6، d = 10. الـ $1s^2\\,2s^2\\,2p^6\\,3s^2\\,3p^6$ بياخدوا 18 electrons، والـ 2 الأخرانيين بيروحوا للـ 4s. الشكل المختصر: $[\\mathrm{Ar}]\\,4s^2$. وده بالظبط المكان اللي الكتاب بيبدأ منه الـ first transition series: بعد الـ calcium، الـ 3d بيبدأ يتملي."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":44,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-atom.electron-configuration-writing-2","kind":"question","version":1,"ord":59,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"atom.electron-configuration-writing","concepts":[{"concept_id":"atom.electron-configuration-writing","role":"primary"}],"title":"chem-s3-en.question-atom.electron-configuration-writing-2","payload":{"stem":"Which is the correct short (noble-gas core) configuration of gallium ($_{31}$Ga)?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$[\\mathrm{Ar}]\\,4s^2\\,3d^{10}\\,4p^1$","correct":true},{"id":"b","text":"$[\\mathrm{Ar}]\\,4s^2\\,4p^1$","correct":false},{"id":"c","text":"$[\\mathrm{Ar}]\\,4s^2\\,3d^{11}$","correct":false},{"id":"d","text":"$[\\mathrm{Kr}]\\,4s^2\\,3d^{10}\\,4p^1$","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.8 (short form with the [Ar] core)","difficulty":3,"concept_ids":["atom.electron-configuration-writing"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! [Ar] gives 18 electrons, and 2 + 10 + 1 = 13 more makes 31."},"b":{"why":"Count the electrons: 18 + 2 + 1 = 21, not 31. The 3d sublevel fills between 4s and 4p.","feedback":"Misconception: After 4s comes 4p; the 3d sublevel is skipped because level 3 is already 'done' at argon."},"c":{"why":"A d sublevel holds at most 10 electrons, so $3d^{11}$ cannot exist.","feedback":"Misconception: A d sublevel can hold more than 10 electrons."},"d":{"why":"Krypton has 36 electrons, more than gallium, so it cannot be the core. The core is the noble gas before gallium.","feedback":"Misconception: The core is the noble gas after the element (or any nearby noble gas)."}},"explanation":"Step 1: take the noble gas before gallium: argon, 18 electrons. Step 2: 31 - 18 = 13 electrons remain. Step 3: fill in the Aufbau order: 4s (2), then 3d (10), then 4p (1). So Ga is $[\\mathrm{Ar}]\\,4s^2\\,3d^{10}\\,4p^1$. Always check the total and each sublevel's capacity."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ [Ar] بيدي 18 electrons، و2 + 10 + 1 = 13 زيادة يبقى المجموع 31."},"b":{"why":"عدّ الـ electrons: 18 + 2 + 1 = 21، مش 31. فيه sublevel ناقص بين الـ 4s والـ 4p: الـ 3d.","feedback":"الفكرة الغلط: إن بعد الـ 4s على طول بييجي الـ 4p، والـ 3d sublevel بيتنطّ عشان المستوى 3 'خلص' عند الـ argon."},"c":{"why":"الـ d sublevel بيشيل 10 electrons بالكتير، فمايقدرش ياخد 11، والـ $3d^{11}$ مالوش وجود.","feedback":"الفكرة الغلط: إن الـ d sublevel ممكن يشيل أكتر من 10 electrons."},"d":{"why":"الـ Krypton عنده 36 electrons، أكتر من الـ gallium، فمينفعش يبقى الـ core بتاعه. الـ core لازم يبقى الـ noble gas اللي قبل الـ gallium.","feedback":"الفكرة الغلط: إن الـ core هو الـ noble gas اللي بعد العنصر (أو أي noble gas قريب منه)."}},"explanation":"خطوة 1: هات الـ noble gas اللي قبل الـ gallium: الـ argon، 18 electrons. خطوة 2: 31 - 18 = 13 electrons فاضلين. خطوة 3: املاهم بترتيب الـ Aufbau: الـ 4s (2)، وبعدين الـ 3d (10)، وبعدين الـ 4p (1). يبقى الـ Ga هو $[\\mathrm{Ar}]\\,4s^2\\,3d^{10}\\,4p^1$. ودايمًا راجع المجموع وسعة كل sublevel."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":45,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-pt.blocks-1","kind":"question","version":1,"ord":60,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"pt.blocks","concepts":[{"concept_id":"pt.blocks","role":"primary"}],"title":"chem-s3-en.question-pt.blocks-1","payload":{"stem":"Classify each element into its block, using the sublevel that receives its last electron.","tags":["diagnostic","classify"],"type":"classify","bloom":"apply","answer":{"d":["v","zn"],"p":["cl"],"s":["na","ca"]},"choices":[{"id":"na","text":"$_{11}$Na: $[\\mathrm{Ne}]\\,3s^1$"},{"id":"cl","text":"$_{17}$Cl: $[\\mathrm{Ne}]\\,3s^2\\,3p^5$"},{"id":"ca","text":"$_{20}$Ca: $[\\mathrm{Ar}]\\,4s^2$"},{"id":"v","text":"$_{23}$V: $[\\mathrm{Ar}]\\,4s^2\\,3d^3$"},{"id":"zn","text":"$_{30}$Zn: $[\\mathrm{Ar}]\\,4s^2\\,3d^{10}$"}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.3 (d-block between the s- and p-blocks) and p.8 (configurations)","categories":[{"id":"s","label":"s-block"},{"id":"p","label":"p-block"},{"id":"d","label":"d-block"}],"difficulty":2,"concept_ids":["pt.blocks"],"est_seconds":60},"layer":{"choices":{"v":{"why":"4s is written first, but vanadium's last electron enters 3d (4s fills before 3d), so the outer 4s does not decide its block.","feedback":"Misconception: Block decided by the outer s sublevel (highest level number)."},"ca":{"why":"Calcium sits just before the transition elements, but its last electron enters 4s, an s sublevel, so it is not a d-block element.","feedback":"Misconception: Elements in period 4 near the middle are d-block."},"cl":{"why":"The last sublevel written for chlorine is 3p: its last electron enters a p sublevel, so the first sublevel of the outer level (3s) does not decide its block.","feedback":"Misconception: Block decided by the first sublevel of the outer level (s)."},"na":{"why":"Sodium's last electron enters 3s ($3s^1$), an s sublevel, so Na is in the s-block."},"zn":{"why":"A full d sublevel is still a d sublevel: zinc's last electron enters 3d, so Zn belongs to the d-block.","feedback":"Misconception: A completely filled d sublevel means the element is not in the d-block."}},"explanation":"The block is the sublevel that receives the last electron in the Aufbau order. Na ($3s^1$) and Ca ($4s^2$): s-block. Cl ($3p^5$): p-block. V ($3d^3$) and Zn ($3d^{10}$): d-block. Common mistake 1: putting V in the s-block because 4s is written first. Common mistake 2: putting Zn outside the d-block because its 3d is full. Zn is a d-block element, even though the book does not count it as a transition element."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"v":{"why":"الـ 4s مكتوب الأول، لكن آخر electron في الـ vanadium بيدخل الـ 3d (الـ 4s بتتملي قبل الـ 3d)، فالـ 4s الخارجي مش هو اللي بيحدد الـ block بتاعه.","feedback":"الفكرة الغلط: إن الـ block بيتحدد بالـ s sublevel الخارجي (اللي رقم مستواه أكبر)."},"ca":{"why":"الـ Calcium واقع قبل الـ transition elements على طول، لكن آخر electron عنده بيدخل الـ 4s، وده s sublevel، فهو مش عنصر d-block.","feedback":"الفكرة الغلط: إن عناصر الـ period 4 اللي قريبة من النص تبقى d-block."},"cl":{"why":"آخر sublevel مكتوب في الـ chlorine هو الـ 3p: آخر electron بيدخل p sublevel، فأول sublevel في المستوى الخارجي (الـ 3s) مش هو اللي بيحدد الـ block بتاعه.","feedback":"الفكرة الغلط: إن الـ block بيتحدد بأول sublevel في المستوى الخارجي (s)."},"na":{"why":"آخر electron في الـ sodium بيدخل الـ 3s ($3s^1$)، وده s sublevel، فالـ Na في الـ s-block."},"zn":{"why":"الـ d sublevel المليان لسه d sublevel: آخر electron في الـ zinc بيدخل الـ 3d، فالـ Zn من الـ d-block.","feedback":"الفكرة الغلط: إن الـ d sublevel لما يتملي على الآخر يبقى العنصر مش في الـ d-block."}},"explanation":"الـ block هو الـ sublevel اللي بياخد آخر electron حسب ترتيب الـ Aufbau. الـ Na ($3s^1$) والـ Ca ($4s^2$): s-block. الـ Cl ($3p^5$): p-block. الـ V ($3d^3$) والـ Zn ($3d^{10}$): d-block. غلطة بتتكرر 1: إنك تحط الـ V في الـ s-block عشان الـ 4s مكتوب الأول. غلطة بتتكرر 2: إنك تطلّع الـ Zn برّه الـ d-block عشان الـ 3d بتاعه مليان. الـ Zn عنصر من الـ d-block، حتى لو الكتاب مش بيعتبره transition element."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":46,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te","section_title":"The transition elements","section_path":["Transition Elements","The transition elements"],"relation":"beyond"}]},{"id":"chem-s3-en.question-pt.blocks-2","kind":"question","version":1,"ord":61,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"pt.blocks","concepts":[{"concept_id":"pt.blocks","role":"primary"}],"title":"chem-s3-en.question-pt.blocks-2","payload":{"stem":"Bromine ($_{35}$Br) has the configuration $[\\mathrm{Ar}]\\,4s^2\\,3d^{10}\\,4p^5$. In which block is bromine?","tags":["diagnostic","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"The p-block","correct":true},{"id":"b","text":"The d-block","correct":false},{"id":"c","text":"The s-block","correct":false}],"book_ref":"Prerequisite (earlier grades); used in Ch.1 p.3 (s, p and d blocks of the long-form table)","difficulty":2,"concept_ids":["pt.blocks"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! Bromine's last electron enters 4p, so it is a p-block element."},"b":{"why":"Bromine does contain $3d^{10}$, but 3d was not the last sublevel to receive an electron: 4p fills after it.","feedback":"Misconception: Any element whose configuration contains a d sublevel is in the d-block."},"c":{"why":"4s is the first sublevel of level 4 here; 3d and 4p receive electrons after it.","feedback":"Misconception: Block decided by the outer s sublevel."}},"explanation":"The block is decided by the sublevel that receives the last electron. For bromine, 4s fills, then 3d, then 4p. The last electron enters 4p, so bromine is in the p-block. A full $3d^{10}$ inside the atom does not make it a d-block element."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! آخر electron في الـ bromine بيدخل الـ 4p، يبقى هو p-block element."},"b":{"why":"الـ bromine فعلًا فيه $3d^{10}$، لكن الـ 3d ماكانش آخر sublevel ياخد electron: الـ 4p بيتملي بعده.","feedback":"الفكرة الغلط: إن أي عنصر الـ configuration بتاعه فيه d sublevel يبقى في الـ d-block."},"c":{"why":"الـ 4s هنا هو أول sublevel في المستوى 4؛ الـ 3d والـ 4p بياخدوا electrons بعده.","feedback":"الفكرة الغلط: إن الـ block بيتحدد بالـ s sublevel الخارجي."}},"explanation":"الـ block بيتحدد بالـ sublevel اللي بياخد آخر electron. في الـ bromine، الـ 4s بيتملي، وبعدين الـ 3d، وبعدين الـ 4p. آخر electron بيدخل الـ 4p، يبقى الـ bromine في الـ p-block. ووجود $3d^{10}$ مليان جوه الذرة مش بيخليه d-block element."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":47,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te","section_title":"The transition elements","section_path":["Transition Elements","The transition elements"],"relation":"beyond"}]},{"id":"chem-s3-en.question-te.position-in-periodic-table-1","kind":"question","version":1,"ord":62,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.position-in-periodic-table","concepts":[{"concept_id":"te.position-in-periodic-table","role":"primary"}],"title":"chem-s3-en.question-te.position-in-periodic-table-1","payload":{"stem":"Choose the correct answer: In the long form of the periodic table, the main transition elements occupy ...","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"the middle of the table, between the s-block and the p-block","correct":true},{"id":"b","text":"the right side of the table, after the p-block","correct":false},{"id":"c","text":"the two separate rows below the main table","correct":false},{"id":"d","text":"the left side of the table, before the s-block","correct":false}],"book_ref":"Ch.1 p.3 'The transition elements' (middle of the long form, between s and p blocks)","difficulty":2,"concept_ids":["te.position-in-periodic-table"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! The book places them in the middle of the table, between the (s) and (p) blocks."},"b":{"why":"The right side holds the p-block, ending with the noble gases; the d-block comes before the p-block, not after it.","feedback":"Misconception: Transition elements lie at the right end of the table, near the noble gases."},"c":{"why":"Those two rows are the lanthanides and actinides: they are inner transition elements, not main ones.","feedback":"Misconception: Lanthanides and actinides are the main transition elements."},"d":{"why":"The s-block (groups 1 and 2) is already on the far left; the d-block starts after it, not before it.","feedback":"Misconception: Transition elements come before the s-block (on the far left)."}},"explanation":"The book: the transition elements occupy the middle of the periodic table, between the (s) and (p) blocks. They are more than 60 elements. They are classified into main transition elements (d-block) and inner transition elements (f-block). The two rows under the table are the inner transition elements, which this chapter does not study."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الكتاب بيحطهم في نص الجدول، بين الـ (s) والـ (p) blocks."},"b":{"why":"الجانب اليمين بيخلص بالـ noble gases، والـ transition elements مش هناك: هي واقعة بين اتنين blocks في نص الجدول.","feedback":"الفكرة الغلط: إن الـ transition elements واقعة في آخر الجدول على اليمين، جنب الـ noble gases."},"c":{"why":"الصفين دول هما الـ lanthanides والـ actinides، ودول inner transition elements، مش main.","feedback":"الفكرة الغلط: إن الـ lanthanides والـ actinides هي الـ main transition elements."},"d":{"why":"الـ s-block (الـ groups 1 و2) هو أصلًا اللي في أقصى الشمال، والـ d-block بييجي بعده، مش قبله.","feedback":"الفكرة الغلط: إن الـ transition elements بتيجي قبل الـ s-block (في أقصى الشمال)."}},"explanation":"الكتاب بيقول: الـ transition elements واقعة في نص الـ periodic table، بين الـ (s) والـ (p) blocks، وعددها أكتر من 60 عنصر. وبتنقسم لـ main transition elements (الـ d-block) و inner transition elements (الـ f-block). والصفين اللي تحت الجدول دول هما الـ inner transition elements، والفصل ده مش بيدرسهم."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":48,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te","section_title":"The transition elements","section_path":["Transition Elements","The transition elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.d-block-groups-1","kind":"question","version":1,"ord":63,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.d-block-groups","concepts":[{"concept_id":"te.d-block-groups","role":"primary"}],"title":"chem-s3-en.question-te.d-block-groups-1","payload":{"stem":"Choose the correct answer: The d-block of the periodic table contains ...","tags":["exam-style","choose","give-reasons"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"10 vertical columns, because the d sublevel can take up to 10 electrons","correct":true},{"id":"b","text":"5 vertical columns, because the d sublevel has 5 orbitals","correct":false},{"id":"c","text":"8 vertical columns, because there are 8 B groups (IIIB to IIB)","correct":false}],"book_ref":"Ch.1 p.3 'The Main transition elements (elements of d-block)' (ten vertical columns)","difficulty":2,"concept_ids":["te.d-block-groups"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Correct! The d sublevel takes up to 10 electrons, and in general each column adds one more d electron, from $(n-1)d^1$ to $(n-1)d^{10}$."},"b":{"why":"A d sublevel does have 5 orbitals, but in general each column adds one electron, not one orbital, and 5 orbitals hold 10 electrons.","feedback":"Misconception: One column per d orbital (orbitals confused with electrons)."},"c":{"why":"There are 8 group labels, but one of them, VIII, covers three columns, so there are more columns than labels.","feedback":"Misconception: The d-block has 8 columns because there are 8 B-groups (group VIII taken as one column)."}},"explanation":"In the main transition elements, electrons occupy the d sublevel in sequence. The d sublevel can take up to ten electrons, so the d-block contains ten vertical columns. The first column ends with $ns^2\\,(n-1)d^1$; the last ends with $ns^2\\,(n-1)d^{10}$. There are 8 group labels only because group VIII alone takes three columns (8, 9, 10)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! في القاعدة العامة كل column بيزوّد electron واحد كمان في الـ d، من $(n-1)d^1$ لحد $(n-1)d^{10}$."},"b":{"why":"الـ d sublevel فعلًا فيه 5 orbitals، لكن في القاعدة العامة كل column بيزوّد electron واحد، مش orbital، والـ 5 orbitals بيشيلوا 10 electrons.","feedback":"الفكرة الغلط: إن فيه column لكل d orbital (لخبطة بين الـ orbitals والـ electrons)."},"c":{"why":"فيه 8 أسماء للـ groups، لكن واحد منهم، الـ VIII، بيغطي تلات columns، فعدد الـ columns أكتر من عدد الأسماء.","feedback":"الفكرة الغلط: إن الـ d-block فيه 8 columns عشان فيه 8 B-groups (يعني اعتبار الـ group VIII column واحد)."}},"explanation":"في الـ main transition elements، الـ electrons بتشغل الـ d sublevel بالتتابع. والـ d sublevel بيشيل لحد عشرة electrons، فالـ d-block فيه عشرة vertical columns. أول column بيخلص بـ $ns^2\\,(n-1)d^1$، وآخر column بيخلص بـ $ns^2\\,(n-1)d^{10}$. وأسماء الـ groups 8 لأن الـ group VIII لوحده واخد تلات columns (8، 9، 10)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":49,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.transition-series-1","kind":"question","version":1,"ord":64,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.transition-series","concepts":[{"concept_id":"te.transition-series","role":"primary"}],"title":"chem-s3-en.question-te.transition-series-1","payload":{"stem":"Choose the correct answer: The second transition series includes the elements in which the ... sublevel is filled successively, and it lies in the ... period.","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"4d ... fifth","correct":true},{"id":"b","text":"5d ... fifth","correct":false},{"id":"c","text":"4d ... fourth","correct":false},{"id":"d","text":"2d ... second","correct":false}],"book_ref":"Ch.1 p.4 'The second transition series' (4d, fifth period)","difficulty":2,"concept_ids":["te.transition-series"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! The d sublevel being filled is one level below the period: 4d in period 5."},"b":{"why":"The period is right, but the filling d sublevel is not in the outer level: it is $(n-1)$, not $n$.","feedback":"Misconception: The d sublevel filled has the same number as the period (5d in period 5)."},"c":{"why":"The sublevel is right, but the first series is already in period 4, so the second series is in period 5.","feedback":"Misconception: The period number equals the number of the d sublevel being filled."},"d":{"why":"A d sublevel does not exist in level 2, and the second series sits in period 5.","feedback":"Misconception: Series number = number of the d sublevel and of the period."}},"explanation":"The four series fill $(n-1)d$, one level below the period number $n$. First series: 3d, period 4 (Sc to Zn). Second series: 4d, period 5 (Y to Cd). Third series: 5d, period 6 (La to Hg). Fourth series: 6d, period 7. Key words from the book: 'the sublevel (4d) is filled successively', 'found in the fifth period'."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ d sublevel اللي بيتملي بيبقى في مستوى أقل من رقم الـ period بواحد: يعني 4d في الـ period 5."},"b":{"why":"الـ period صح، لكن الـ d sublevel اللي بيتملي مش في المستوى الخارجي: بيبقى في المستوى $(n-1)$، مش $n$.","feedback":"الفكرة الغلط: إن الـ d sublevel اللي بيتملي رقمه نفس رقم الـ period (5d في الـ period 5)."},"c":{"why":"الـ sublevel صح، لكن الـ period 4 دي بتاعة الـ first series، فالـ second series في الـ period اللي بعدها.","feedback":"الفكرة الغلط: إن رقم الـ period بيساوي رقم الـ d sublevel اللي بيتملي."},"d":{"why":"مفيش d sublevel في المستوى 2، والـ second series مش في الـ second period.","feedback":"الفكرة الغلط: إن رقم الـ series = رقم الـ d sublevel = رقم الـ period."}},"explanation":"الـ transition series الأربعة بتملا الـ $(n-1)d$، يعني مستوى واحد تحت رقم الـ period $n$. الـ first series: 3d، الـ period 4 (من الـ Sc للـ Zn). الـ second series: 4d، الـ period 5 (من الـ Y للـ Cd). الـ third series: 5d، الـ period 6 (من الـ La للـ Hg). الـ fourth series: 6d، الـ period 7. الكلمات المهمة من الكتاب: 'the sublevel (4d) is filled successively'، و'found in the fifth period'."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":50,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.first-series-elements-1","kind":"question","version":1,"ord":65,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.first-series-elements","concepts":[{"concept_id":"te.first-series-elements","role":"primary"}],"title":"chem-s3-en.question-te.first-series-elements-1","payload":{"stem":"Choose the correct answer: The first transition series starts with ... and ends with ...","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"scandium ($_{21}$Sc) ... zinc ($_{30}$Zn)","correct":true},{"id":"b","text":"scandium ($_{21}$Sc) ... copper ($_{29}$Cu)","correct":false},{"id":"c","text":"titanium ($_{22}$Ti) ... zinc ($_{30}$Zn)","correct":false},{"id":"d","text":"calcium ($_{20}$Ca) ... zinc ($_{30}$Zn)","correct":false}],"book_ref":"Ch.1 p.4 'The first transition series' (from $_{21}$Sc to $_{30}$Zn)","difficulty":2,"concept_ids":["te.first-series-elements"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Ten elements, from Sc ($4s^2\\,3d^1$) to Zn ($4s^2\\,3d^{10}$)."},"b":{"why":"The series includes every element that fills 3d, and zinc, not copper, completes $3d^{10}$ with $4s^2$.","feedback":"Misconception: Zinc is left out of the series because it is not counted as a transition element."},"c":{"why":"Scandium's configuration, $4s^2\\,3d^1$, already has an electron in 3d, so the series starts before titanium.","feedback":"Misconception: Scandium is not a transition element, so the series starts at titanium."},"d":{"why":"Calcium ends with $4s^2$ and has no 3d electron, so it is not in the series; scandium puts the first electron into 3d.","feedback":"Misconception: The series starts at the beginning of the fourth period's filling (Ca)."}},"explanation":"The first transition series includes the elements in which the 3d sublevel is filled successively. It is in the fourth period after calcium. It has ten elements: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn. It starts with scandium ($_{21}$Sc, $4s^2\\,3d^1$) and ends with zinc ($_{30}$Zn, $4s^2\\,3d^{10}$). Note: zinc belongs to the series even though the book does not consider it a transition element."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! عشرة عناصر، من الـ Sc ($4s^2\\,3d^1$) لحد الـ Zn ($4s^2\\,3d^{10}$)."},"b":{"why":"السلسلة فيها كل عنصر بيملا الـ 3d، والـ zinc، مش الـ copper، هو اللي بيكمّل الـ $3d^{10}$ مع الـ $4s^2$.","feedback":"الفكرة الغلط: إن الـ zinc مش من السلسلة عشان مش بيتحسب transition element."},"c":{"why":"الـ configuration بتاع الـ scandium، $4s^2\\,3d^1$، فيه electron في الـ 3d أصلًا، فالسلسلة بتبدأ قبل الـ titanium.","feedback":"الفكرة الغلط: إن الـ scandium مش transition element، فالسلسلة بتبدأ من الـ titanium."},"d":{"why":"الـ calcium آخره $4s^2$ ومفيهوش ولا electron في الـ 3d، فهو مش من السلسلة؛ الـ scandium هو اللي بيحط أول electron في الـ 3d.","feedback":"الفكرة الغلط: إن السلسلة بتبدأ من أول ملء الـ fourth period (الـ Ca)."}},"explanation":"الـ first transition series فيها العناصر اللي الـ 3d sublevel بيتملي فيها بالتتابع. مكانها في الـ fourth period بعد الـ calcium. فيها عشرة عناصر: Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn. بتبدأ بالـ scandium ($_{21}$Sc، $4s^2\\,3d^1$) وبتخلص بالـ zinc ($_{30}$Zn، $4s^2\\,3d^{10}$). خلّي بالك: الـ zinc من السلسلة، مع إن الكتاب مش بيعتبره transition element."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":51,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.position-in-periodic-table-2","kind":"question","version":1,"ord":66,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.position-in-periodic-table","concepts":[{"concept_id":"te.position-in-periodic-table","role":"primary"}],"title":"chem-s3-en.question-te.position-in-periodic-table-2","payload":{"stem":"Compare: classify each description as belonging to the main transition elements or the inner transition elements.","tags":["exam-style","compare","classify"],"type":"classify","bloom":"understand","answer":{"main":["d4","first","study"],"inner":["f4","lan","f5"]},"choices":[{"id":"d4","text":"Their atoms fill the 4d sublevel"},{"id":"f4","text":"Their atoms fill the 4f sublevel"},{"id":"lan","text":"The lanthanides"},{"id":"first","text":"The elements of the first transition series"},{"id":"f5","text":"Their atoms fill the 5f sublevel"},{"id":"study","text":"The elements studied in this chapter"}],"book_ref":"Ch.1 p.3 'The transition elements' (main and inner transition elements) and p.4 (series fill 3d, 4d, 5d, 6d)","categories":[{"id":"main","label":"Main transition elements"},{"id":"inner","label":"Inner transition elements"}],"difficulty":3,"concept_ids":["te.position-in-periodic-table"],"est_seconds":90},"layer":{"choices":{"d4":{"why":"4d and 4f look alike, but the letter here is d, and the main transition elements fill a d sublevel.","feedback":"Misconception: Mixing up 4d and 4f (any sublevel of level 4 beyond p is inner)."},"f4":{"why":"The letter of this sublevel is f, not d, while main transition elements fill a d sublevel.","feedback":"Misconception: Any sublevel filled inside the table is part of the d-block."},"f5":{"why":"The sublevel letter here is f, while main transition elements fill d sublevels only.","feedback":"Misconception: Any sublevel filled in period 7 belongs to the main transition elements."},"lan":{"why":"The lanthanides are drawn in a separate row under the table, not inside the d-block: their atoms fill 4f.","feedback":"Misconception: Lanthanides and actinides are main transition elements."},"first":{"why":"The first series fills 3d, which is a d sublevel.","feedback":"Misconception: The first transition series is part of the inner transition elements."},"study":{"why":"The book says this chapter studies one class only: the d-block elements of the four transition series.","feedback":"Misconception: This chapter studies all transition elements, including the f-block."}},"explanation":"The transition elements are classified into two classes. Main transition elements (d-block): their atoms fill a d sublevel (3d, 4d, 5d, 6d). They form the four transition series, and this chapter studies them only. Inner transition elements (f-block): their atoms fill an f sublevel (4f = lanthanides, 5f = actinides). They are the two rows under the table. Most common mistake: counting the lanthanides as main transition elements because the lanthanides and actinides lie in periods 6 and 7."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"d4":{"why":"الـ 4d والـ 4f شكلهم قريب من بعض، لكن الحرف هنا d: الـ 4d هو d sublevel.","feedback":"الفكرة الغلط: إنك تلخبط بين الـ 4d والـ 4f (كأن أي sublevel في المستوى 4 بعد الـ p يبقى inner)."},"f4":{"why":"الحرف هنا f: الـ 4f هو f sublevel، مش d sublevel.","feedback":"الفكرة الغلط: إن أي sublevel بيتملي جوه الجدول يبقى جزء من الـ d-block."},"f5":{"why":"الحرف هنا f: الـ 5f هو f sublevel، مش d sublevel.","feedback":"الفكرة الغلط: إن أي sublevel بيتملي في الـ period 7 يبقى تبع الـ main transition elements."},"lan":{"why":"الـ lanthanides مرسومة في صف لوحدها تحت الجدول، مش جوه الـ d-block: ذراتها بتملا الـ 4f.","feedback":"الفكرة الغلط: إن الـ lanthanides والـ actinides من الـ main transition elements."},"first":{"why":"الـ first series بتملا الـ 3d، وده d sublevel، مش f.","feedback":"الفكرة الغلط: إن الـ first transition series جزء من الـ inner transition elements."},"study":{"why":"الكتاب بيقول إنه هيدرس نوع واحد منهم تحديدًا: العناصر اللي بتملا d sublevel (الـ d-block).","feedback":"الفكرة الغلط: إن الفصل ده بيدرس الـ transition elements كلها، ومعاها الـ f-block."}},"explanation":"الـ transition elements بتنقسم لنوعين. الـ main transition elements (الـ d-block): ذراتها بتملا d sublevel (3d, 4d, 5d, 6d)، وهي اللي بتكوّن الـ transition series الأربعة، والفصل ده بيدرسها هي تحديدًا. الـ inner transition elements (الـ f-block): ذراتها بتملا f sublevel (الـ 4f = الـ lanthanides، والـ 5f = الـ actinides)، وهي الصفين اللي تحت الجدول. أشهر غلطة: إنك تعدّ الـ lanthanides من الـ main transition elements عشان الـ lanthanides والـ actinides واقعين في الـ periods 6 و7."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":52,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te","section_title":"The transition elements","section_path":["Transition Elements","The transition elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-te.d-block-groups-2","kind":"question","version":1,"ord":67,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.d-block-groups","concepts":[{"concept_id":"te.d-block-groups","role":"primary"}],"title":"chem-s3-en.question-te.d-block-groups-2","payload":{"stem":"Arrange the following groups of the d-block from left to right as they appear in the periodic table.","tags":["exam-style","arrange"],"type":"order","bloom":"remember","answer":["iiib","vb","viib","viii","ib","iib"],"choices":[{"id":"ib","text":"IB"},{"id":"viib","text":"VIIB"},{"id":"iiib","text":"IIIB"},{"id":"viii","text":"VIII"},{"id":"iib","text":"IIB"},{"id":"vb","text":"VB"}],"book_ref":"Ch.1 p.3 'The Main transition elements (elements of d-block)' (groups IIIB ... IIB)","difficulty":3,"concept_ids":["te.d-block-groups"],"est_seconds":60},"layer":{"choices":{"ib":{"why":"A small Roman numeral does not mean an early column: the book gives IB the modern group number 11."},"vb":{"why":"VB's configuration ends with $(n-1)d^3$: it has more d electrons than IIIB and fewer than VIIB."},"iib":{"why":"IIB's configuration ends with $(n-1)d^{10}$: its d sublevel is completely filled, the most d electrons of these groups."},"iiib":{"why":"IIIB's configuration ends with $(n-1)d^1$: it holds the fewest d electrons of these groups."},"viib":{"why":"VIIB's configuration ends with $(n-1)d^5$: it has five d electrons, more than VB and fewer than VIII."},"viii":{"why":"VIII covers three columns, the modern groups 8, 9 and 10."}},"explanation":"From left to right the d-block groups are: IIIB (3), IVB (4), VB (5), VIB (6), VIIB (7), VIII (8, 9, 10), IB (11), IIB (12). So the order here is IIIB, VB, VIIB, VIII, IB, IIB. Most common mistake: putting IB and IIB first because 'I' and 'II' are smaller numbers. Use the modern numbers 3 to 12 to check yourself."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"ib":{"why":"الرقم الروماني الصغير مش معناه إن الـ column بدري: الكتاب بيدّي الـ IB رقم الـ group الحديث 11."},"vb":{"why":"الـ configuration بتاع الـ VB بيخلص بـ $(n-1)d^3$: الـ d electrons بتوعه أكتر من بتوع الـ IIIB وأقل من بتوع الـ VIIB."},"iib":{"why":"الـ configuration بتاع الـ IIB بيخلص بـ $(n-1)d^{10}$: الـ d sublevel بتاعه مليان خالص، وده أكبر عدد d electrons في الـ groups دي."},"iiib":{"why":"الـ configuration بتاع الـ IIIB بيخلص بـ $(n-1)d^1$: ده أقل عدد d electrons في الـ groups دي."},"viib":{"why":"الـ VIIB فيه 5 d electrons: الـ configuration بتاعه بيخلص بـ $(n-1)d^5$."},"viii":{"why":"الـ VIII بيغطي تلات columns، هما الـ groups الحديثة 8 و9 و10."}},"explanation":"الـ d-block groups من الشمال لليمين: IIIB (3)، IVB (4)، VB (5)، VIB (6)، VIIB (7)، VIII (8، 9، 10)، IB (11)، IIB (12). يعني الترتيب هنا: IIIB، VB، VIIB، VIII، IB، IIB. أشهر غلطة: إنك تحط الـ IB والـ IIB الأول عشان 'I' و'II' أرقام أصغر. استخدم الأرقام الحديثة من 3 لـ 12 عشان تراجع نفسك."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":53,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.transition-series-2","kind":"question","version":1,"ord":68,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.transition-series","concepts":[{"concept_id":"te.transition-series","role":"primary"}],"title":"chem-s3-en.question-te.transition-series-2","payload":{"stem":"Rutherfordium ($_{104}$Rf) lies in the seventh period. Its configuration ends with $5f^{14}\\,7s^2\\,6d^2$. To which group of elements does it belong?","tags":["exam-style","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"The fourth transition series","correct":true},{"id":"b","text":"The seventh transition series","correct":false},{"id":"c","text":"The inner transition elements, because it contains $5f^{14}$","correct":false},{"id":"d","text":"The sixth transition series, because it fills 6d","correct":false}],"book_ref":"Ch.1 p.5 'The fourth transition series' (6d, seventh period)","difficulty":3,"concept_ids":["te.transition-series"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! Rf fills the 6d sublevel in the seventh period, and that is the fourth transition series."},"b":{"why":"There are only four transition series: Rf fills 6d, and 6d is filled in the fourth series.","feedback":"Misconception: Series number = period number."},"c":{"why":"The 5f sublevel here is already complete; Rf's last electrons go to 6d, so 5f does not decide the block.","feedback":"Misconception: Any element with f electrons in its configuration is an inner transition element."},"d":{"why":"6d is right, but the series number is not the sublevel number: 3d is the first series, so 6d is the fourth.","feedback":"Misconception: Series number = the number of the d sublevel being filled."}},"explanation":"Rf's last electrons enter 6d: $7s^2\\,6d^2$. The $5f^{14}$ is complete, so it does not decide the block. The book: in the fourth transition series, the 6d sublevel is filled successively. These elements are found in the seventh period. Link: 3d = first, 4d = second, 5d = third, 6d = fourth. Neither the period number (7) nor the sublevel number (6) is the series number."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ Rf بيملا الـ 6d sublevel في الـ seventh period، ودي هي الـ fourth transition series."},"b":{"why":"مفيش غير أربع transition series، فمفيش seventh series. الـ Rf بيملا الـ 6d sublevel، والـ series اللي بتملاه هي آخر واحدة من الأربعة.","feedback":"الفكرة الغلط: إن رقم الـ series = رقم الـ period."},"c":{"why":"الـ 5f sublevel هنا مكتمل خلاص، وآخر electrons في الـ Rf بتدخل الـ 6d، فهو مش inner transition element.","feedback":"الفكرة الغلط: إن أي عنصر في الـ configuration بتاعته f electrons يبقى inner transition element."},"d":{"why":"الـ 6d صح، لكن رقم الـ series مش هو رقم الـ sublevel: الـ first series بتملا الـ 3d، فالـ series اللي بتملا الـ 6d هي الرابعة.","feedback":"الفكرة الغلط: إن رقم الـ series = رقم الـ d sublevel اللي بيتملي."}},"explanation":"آخر electrons في الـ Rf بتدخل الـ 6d: $7s^2\\,6d^2$. الـ $5f^{14}$ مكتمل، فمش هو اللي بيحدد الـ block. الكتاب بيقول: في الـ fourth transition series، الـ 6d sublevel بيتملي بالتتابع، والعناصر دي موجودة في الـ seventh period. اربطها كده: 3d = first، 4d = second، 5d = third، 6d = fourth. لا رقم الـ period (7) ولا رقم الـ sublevel (6) هو رقم الـ series."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":54,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-te.first-series-elements-2","kind":"question","version":1,"ord":69,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.first-series-elements","concepts":[{"concept_id":"te.first-series-elements","role":"primary"}],"title":"chem-s3-en.question-te.first-series-elements-2","payload":{"stem":"The table shows the percent of each element of the first transition series in the earth's crust. Which statement is correct?","tags":["exam-style","data-reading"],"type":"mcq","bloom":"analyze","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["% wt",0.0026,0.66,0.02,0.014,0.11,5,0.003,0.0089,0.0068,0.0078]],"caption":"Percent by weight in the earth's crust (book values)","headers":["element","Sc","Ti","V","Cr","Mn","Fe","Co","Ni","Cu","Zn"]},"children":[]}}},"choices":[{"id":"a","text":"Iron is the most abundant, and scandium is the least abundant.","correct":true},{"id":"b","text":"Iron is the most abundant, and cobalt is the least abundant.","correct":false},{"id":"c","text":"The percent decreases steadily from Sc to Zn as the atomic number increases.","correct":false},{"id":"d","text":"Cobalt has a very small percent, so it has little economic importance.","correct":false}],"book_ref":"Ch.1 p.5 table: percent of each first-series element in the earth's crust","difficulty":3,"concept_ids":["te.first-series-elements"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Correct! Fe has 5%, and Sc has only 0.0026%, the smallest value in the table."},"b":{"why":"Compare 0.003 and 0.0026 digit by digit: 0.0030 is larger than 0.0026, so cobalt is not the least abundant.","feedback":"Misconception: A decimal with more digits (0.0026) is the bigger number."},"c":{"why":"The values go up and down across the row: Ti is 0.66, V drops to 0.02, then Fe rises to 5.","feedback":"Misconception: Properties always change steadily with atomic number across the series."},"d":{"why":"Cobalt-60 and cobalt magnets show its use: a small amount in the crust does not mean little use, and the book says these elements have high economic importance.","feedback":"Misconception: Being abundant in the crust is what makes a metal economically important."}},"explanation":"Read each value from the table. Iron (5) is by far the largest. The smallest is scandium (0.0026), just below cobalt (0.003 = 0.0030). The values go up and down across the series, for example Ti 0.66 and V 0.02. So there is no steady trend. The book adds: together these elements form only nearly 7% of the crust, but they have high economic importance. Tip: to compare decimals, write them with the same number of digits."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ Fe نسبته 5%، والـ Sc نسبته 0.0026% يدوب، وهي أصغر قيمة في الجدول."},"b":{"why":"لما نقارن 0.003 و0.0026 رقم رقم: 0.0030 أكبر من 0.0026، فالـ cobalt مش هو الأقل.","feedback":"الفكرة الغلط: إن الرقم العشري اللي فيه أرقام أكتر (0.0026) يبقى هو الأكبر."},"c":{"why":"القيم بتطلع وتنزل على طول الصف: الـ Ti بـ 0.66، والـ V بينزل لـ 0.02، وبعدين الـ Fe يطلع لـ 5.","feedback":"الفكرة الغلط: إن الخواص دايمًا بتتغير بانتظام مع الـ atomic number على طول السلسلة."},"d":{"why":"الـ cobalt-60 والمغناطيس اللي معمول من الـ cobalt بيبيّنوا استخداماته: الكمية الصغيرة في القشرة الأرضية مش معناها إن استخدامه قليل، والكتاب بيقول إن العناصر دي ليها أهمية اقتصادية كبيرة.","feedback":"الفكرة الغلط: إن كتر وجود الـ metal في القشرة الأرضية هو اللي بيدّيله أهميته الاقتصادية."}},"explanation":"اقرا كل قيمة من الجدول. الـ iron (5) هو الأكبر بفرق كبير. والأصغر هو الـ scandium (0.0026)، تحت الـ cobalt بشوية (0.003 = 0.0030). القيم بتطلع وتنزل على طول السلسلة، مثلًا الـ Ti 0.66 والـ V 0.02، يعني مفيش اتجاه ثابت. والكتاب بيضيف: العناصر دي مع بعض بتمثّل يدوب حوالي 7% من القشرة الأرضية، لكن ليها أهمية اقتصادية عالية. نصيحة: عشان تقارن أرقام عشرية، اكتبهم بنفس عدد الأرقام."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":55,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.abundance","section_title":"Percent of each element in the earth's crust","section_path":["Transition Elements","The First Transition Series","Percent of each element in the earth's crust"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.position-in-periodic-table-3","kind":"question","version":1,"ord":70,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.position-in-periodic-table","concepts":[{"concept_id":"te.position-in-periodic-table","role":"primary"}],"title":"chem-s3-en.question-te.position-in-periodic-table-3","payload":{"stem":"The configurations of three elements end as follows:\n$_{72}$X: $6s^2\\,4f^{14}\\,5d^2$\n$_{63}$Y: $6s^2\\,4f^7$\n$_{31}$Z: $4s^2\\,3d^{10}\\,4p^1$\nConsider the following statements:\n(I) X is an inner transition element, because its atom contains a full 4f sublevel.\n(II) Y is an inner transition element.\n(III) Z is a main transition element, because its atom contains a full 3d sublevel.\nWhich of these statements is/are correct?","tags":["exam-style","statements-I-II-III"],"type":"mcq","bloom":"analyze","choices":[{"id":"a","text":"II only","correct":true},{"id":"b","text":"I and II only","correct":false},{"id":"c","text":"II and III only","correct":false},{"id":"d","text":"I, II and III","correct":false}],"book_ref":"Ch.1 p.3 'The transition elements' (main = d-block, electrons occupy the d sublevel; inner transition elements) and p.4 periodic table","difficulty":4,"concept_ids":["te.position-in-periodic-table"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Correct! The sublevel being filled last decides the class, not the full sublevels inside the atom."},"b":{"why":"(I) is wrong: X has a full 4f sublevel, but it is now filling 5d, so it is a main transition element.","feedback":"Misconception: Any atom that contains f electrons is an inner transition element."},"c":{"why":"(III) is wrong: Z has a full 3d sublevel, but its last electron goes to 4p, so Z is a p-block element.","feedback":"Misconception: Any atom that contains d electrons is a main transition element (d-block)."},"d":{"why":"(II) is fine, but (I) and (III) are wrong: the last sublevel in each configuration decides the class (5d for X, 4p for Z), not the full ones.","feedback":"Misconception: The full inner sublevels in an atom decide its block."}},"explanation":"Classify an element by the sublevel its electrons are filling, the last one in the configuration. (I) Wrong: X has a full 4f sublevel, but its electrons are now filling 5d ($5d^2$). So X is a main transition element (d-block, third transition series). (II) Correct: Y is filling the 4f sublevel, so it is an inner transition element (f-block, a lanthanide). (III) Wrong: Z has a full 3d sublevel, but its last electron enters 4p. So Z is a p-block element, not a transition element. Answer: II only. Key idea: main transition elements fill a d sublevel; inner transition elements fill an f sublevel."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! اللي بيحدد النوع هو الـ sublevel اللي بيتملي في الآخر، مش الـ sublevels المليانة اللي جوه الذرة."},"b":{"why":"(I) غلط: الـ X فيه 4f sublevel مليان، لكنه بيملا الـ 5d دلوقتي، فهو مش inner transition element.","feedback":"الفكرة الغلط: إن أي ذرة فيها f electrons تبقى inner transition element."},"c":{"why":"(III) غلط: الـ Z فيه 3d sublevel مليان، لكن آخر electron فيه بيروح الـ 4p، فهو مش main transition element.","feedback":"الفكرة الغلط: إن أي ذرة فيها d electrons تبقى main transition element (من الـ d-block)."},"d":{"why":"(II) سليمة، لكن (I) و(III) غلط: اللي بيحدد النوع هو آخر sublevel في كل configuration، مش الـ sublevels المليانة.","feedback":"الفكرة الغلط: إن الـ inner sublevels المليانة في الذرة هي اللي بتحدد الـ block بتاعها."}},"explanation":"بنصنّف العنصر حسب الـ sublevel اللي الـ electrons بتاعته بتملاه، يعني آخر واحد في الـ configuration. (I) غلط: الـ X فيه 4f sublevel مليان، لكن الـ electrons بتاعته بتملا الـ 5d دلوقتي ($5d^2$). يبقى الـ X ده main transition element (من الـ d-block، في الـ third transition series). (II) صح: الـ Y بيملا الـ 4f sublevel، يبقى inner transition element (من الـ f-block، lanthanide). (III) غلط: الـ Z فيه 3d sublevel مليان، لكن آخر electron فيه بيدخل الـ 4p. يبقى الـ Z عنصر من الـ p-block، مش transition element. الإجابة: II only. الفكرة الأساسية: الـ main transition elements بتملا d sublevel، والـ inner transition elements بتملا f sublevel."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":56,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-te.d-block-groups-3","kind":"question","version":1,"ord":71,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.d-block-groups","concepts":[{"concept_id":"te.d-block-groups","role":"primary"}],"title":"chem-s3-en.question-te.d-block-groups-3","payload":{"stem":"Element X lies in the sixth period. Its configuration ends with $4f^{14}\\,6s^2\\,5d^6$. Which choice gives the group of X and the elements X resembles most?","tags":["exam-style","two-step"],"type":"mcq","bloom":"analyze","choices":[{"id":"a","text":"Group VIII; it resembles its horizontal neighbours more than the element below it","correct":true},{"id":"b","text":"Group VIII; it resembles the element below it more than its horizontal neighbours","correct":false},{"id":"c","text":"Group VIB; it resembles its horizontal neighbours more than the element below it","correct":false},{"id":"d","text":"Group VIB; it resembles the element below it more than its horizontal neighbours","correct":false}],"book_ref":"Ch.1 p.3 'The Main transition elements (elements of d-block)' (columns $d^1$-$d^{10}$; group VIII similar horizontally)","difficulty":5,"concept_ids":["te.d-block-groups"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Correct! $5d^6$ puts X in the sixth d-block column. That is group VIII, whose elements are similar horizontally."},"b":{"why":"The group is right, but group VIII is the exception in the d-block: the book says its elements are similar horizontally more than the elements below them.","feedback":"Misconception: Group VIII elements resemble the elements below them most (like normal groups)."},"c":{"why":"The columns run from $d^1$ (IIIB) upward, so $d^6$ is the sixth column, the first column of group VIII; VIB is the $d^4$ column.","feedback":"Misconception: Group number = number of d electrons (d6 means group VIB)."},"d":{"why":"Counting from $d^1$ (IIIB), $d^6$ is the first column of group VIII, not VIB, and group VIII is the exception whose elements are similar horizontally more than the elements below them.","feedback":"Misconception: Group number = number of d electrons, and every d-block group resembles vertically."}},"explanation":"Step 1 (find the column): X fills 5d, so it is in the d-block (third series). The 4f¹⁴ is complete and does not decide the block. The columns run from $d^1$ (IIIB) to $d^{10}$ (IIB): $d^1$ IIIB, $d^2$ IVB, $d^3$ VB, $d^4$ VIB, $d^5$ VIIB, $d^6$ VIII. So X is in the first column of group VIII (column 8). Step 2 (the property): group VIII is special. The book says its elements are similar horizontally more than the elements below them. Most common mistake: taking the number of d electrons (6) as the group number, which gives VIB."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ $5d^6$ بيحط X في سادس column في الـ d-block. وده الـ group VIII، اللي عناصره بتتشابه أفقيًا."},"b":{"why":"الـ group صح، لكن الـ group VIII هو الاستثناء في الـ d-block: الكتاب بيقول إن عناصره بتتشابه أفقيًا أكتر من العناصر اللي تحتها.","feedback":"الفكرة الغلط: إن عناصر الـ group VIII بتشبه العناصر اللي تحتها أكتر حاجة (زي الـ groups العادية)."},"c":{"why":"الـ columns بتبدأ من $d^1$ (الـ IIIB) وتطلع، فالـ $d^6$ هو الـ column السادس، أول column في الـ group VIII؛ أما الـ VIB فهو column الـ $d^4$.","feedback":"الفكرة الغلط: إن رقم الـ group = عدد الـ d electrons (يعني d6 تبقى group VIB)."},"d":{"why":"الـ columns بتبدأ من الـ IIIB بـ $d^1$، فالـ $d^6$ هو أول column في الـ group VIII، مش VIB؛ وعناصر الـ group VIII بتتشابه أفقيًا أكتر من العناصر اللي تحتها.","feedback":"الفكرة الغلط: إن رقم الـ group = عدد الـ d electrons، وإن كل groups الـ d-block بتتشابه رأسيًا."}},"explanation":"الخطوة 1 (حدد الـ column): X بيملا الـ 5d، يبقى هو في الـ d-block (الـ third series). والـ 4f¹⁴ مكتمل ومش هو اللي بيحدد الـ block. الـ columns ماشية من $d^1$ (IIIB) لحد $d^{10}$ (IIB): $d^1$ IIIB، $d^2$ IVB، $d^3$ VB، $d^4$ VIB، $d^5$ VIIB، $d^6$ VIII. يعني X في أول column من الـ group VIII (column 8). الخطوة 2 (الخاصية): الـ group VIII حالة خاصة. الكتاب بيقول إن عناصره بتتشابه أفقيًا أكتر من العناصر اللي تحتها. أشهر غلطة: إنك تاخد عدد الـ d electrons (6) على إنه رقم الـ group، فيطلع معاك VIB."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":57,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.transition-series-3","kind":"question","version":1,"ord":72,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.transition-series","concepts":[{"concept_id":"te.transition-series","role":"primary"}],"title":"chem-s3-en.question-te.transition-series-3","payload":{"stem":"The configurations of three elements end as follows:\n$_{25}$X: $4s^2\\,3d^5$\n$_{43}$Y: $5s^2\\,4d^5$\n$_{73}$Z: $6s^2\\,4f^{14}\\,5d^3$\nConsider the following statements:\n(I) X and Y belong to different transition series, although both have five electrons in their d sublevel.\n(II) Y lies in the fourth period, because its atom fills the 4d sublevel.\n(III) Z belongs to the third transition series and lies in the sixth period.\nWhich of these statements is/are correct?","tags":["exam-style","statements-I-II-III"],"type":"mcq","bloom":"analyze","choices":[{"id":"a","text":"I and III only","correct":true},{"id":"b","text":"I and II only","correct":false},{"id":"c","text":"III only","correct":false},{"id":"d","text":"I, II and III","correct":false}],"book_ref":"Ch.1 p.4 'The first, second and third transition series' (3d, 4d, 5d filled successively; fourth, fifth, sixth periods)","difficulty":4,"concept_ids":["te.transition-series"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Correct! The d sublevel being filled names the series, and the outer s level gives the period."},"b":{"why":"(II) does not hold: the outer s level gives the period, so Y, with outer 5s, lies in the fifth period. Z still fills 5d (its 4f is already full), so it stays in the third transition series.","feedback":"Misconception: The period number equals the number of the d sublevel being filled; the 4f electrons move Z out of the third series."},"c":{"why":"(I) holds too: X and Y both have $d^5$, but X fills 3d and Y fills 4d, so they belong to different transition series.","feedback":"Misconception: Elements with the same number of d electrons belong to the same transition series."},"d":{"why":"(II) does not hold: Y's outer sublevel is 5s, and the outer s level gives the period, so Y lies in the fifth period, not the fourth.","feedback":"Misconception: The period number equals the number of the d sublevel being filled (4d in period 4)."}},"explanation":"(I) holds: X fills 3d, so it is in the first transition series; Y fills 4d, so it is in the second transition series. Having five d electrons each does not put them in the same series. (II) does not hold: Y's outer sublevel is 5s, so it lies in the fifth period. The second transition series fills 4d and lies in the fifth period. (III) holds: Z fills 5d (its 4f is already full), so it is in the third transition series, in the sixth period. Answer: I and III only. Rule for the transition series: the series in period $n$ fills the $(n-1)d$ sublevel."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ d sublevel اللي بيتملي هو اللي بيحدد الـ series، والمستوى الخارجي s هو اللي بيدّيك الـ period."},"b":{"why":"(II) مش سليمة: المستوى الخارجي s هو اللي بيحدد الـ period، فالـ Y اللي الخارجي بتاعه 5s موجود في الـ fifth period. والـ Z لسه بيملا الـ 5d (والـ 4f بتاعه مليان خلاص)، فبيفضل في الـ third transition series.","feedback":"الفكرة الغلط: إن رقم الـ period بيساوي رقم الـ d sublevel اللي بيتملي، وإن الـ 4f electrons بتطلّع الـ Z برّه الـ third series."},"c":{"why":"(I) سليمة هي كمان: الـ X والـ Y الاتنين عندهم $d^5$، لكن الـ X بيملا الـ 3d والـ Y بيملا الـ 4d، فهما في transition series مختلفة.","feedback":"الفكرة الغلط: إن العناصر اللي ليها نفس عدد الـ d electrons بتبقى في نفس الـ transition series."},"d":{"why":"(II) مش سليمة: الـ sublevel الخارجي للـ Y هو 5s، والمستوى الخارجي s هو اللي بيحدد الـ period، فالـ Y في الـ fifth period، مش الـ fourth.","feedback":"الفكرة الغلط: إن رقم الـ period بيساوي رقم الـ d sublevel اللي بيتملي (4d في الـ period 4)."}},"explanation":"(I) سليمة: الـ X بيملا الـ 3d، فهو في الـ first transition series؛ والـ Y بيملا الـ 4d، فهو في الـ second transition series. إن كل واحد فيهم عنده خمسة d electrons ده مش معناه إنهم في نفس الـ series. (II) مش سليمة: الـ sublevel الخارجي للـ Y هو 5s، فهو في الـ fifth period. الـ second transition series بتملا الـ 4d وموجودة في الـ fifth period. (III) سليمة: الـ Z بيملا الـ 5d (والـ 4f بتاعه مليان خلاص)، فهو في الـ third transition series، في الـ sixth period. الإجابة: I and III only. قاعدة الـ transition series: الـ series اللي في الـ period $n$ بتملا الـ $(n-1)d$ sublevel."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":58,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.first-series-elements-3","kind":"question","version":1,"ord":73,"group_id":"chem-s3-en.ch1.practice.te-position","primary_concept_id":"te.first-series-elements","concepts":[{"concept_id":"te.first-series-elements","role":"primary"}],"title":"chem-s3-en.question-te.first-series-elements-3","payload":{"stem":"Element X belongs to the first transition series. Its atomic number is 4 more than that of the first element of this series. The symbol of X is ...","tags":["exam-style","two-step"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Mn","correct":true},{"id":"b","text":"Mg","correct":false},{"id":"c","text":"Cr","correct":false},{"id":"d","text":"Fe","correct":false}],"book_ref":"Ch.1 p.5 '1-The First Transition Series' (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) and p.4 (Sc = 21)","difficulty":4,"concept_ids":["te.first-series-elements"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Correct! The series starts with Sc (21). 21 + 4 = 25, which is manganese, Mn."},"b":{"why":"Mg is the symbol of magnesium, a different element; the element with atomic number 25 is manganese.","feedback":"Misconception: Mixing up the symbols of manganese (Mn) and magnesium (Mg)."},"c":{"why":"In order, Sc 21, Ti 22, V 23, Cr 24, so Cr is 21 + 3, not 21 + 4.","feedback":"Misconception: Swapping the order of Cr and Mn."},"d":{"why":"The series starts with scandium (21), not titanium; starting at titanium gives 22 + 4 = 26, which is Fe.","feedback":"Misconception: Scandium is not part of the series, so the series starts at titanium (22 + 4 = 26)."}},"explanation":"Step 1: the first element of the first transition series is scandium, $_{21}$Sc. Step 2: 21 + 4 = 25. In order: Sc 21, Ti 22, V 23, Cr 24, Mn 25, Fe 26, Co 27, Ni 28, Cu 29, Zn 30. So X is manganese, Mn. Common errors: starting the series at Ti (gives Fe), swapping Cr and Mn, or writing Mg (magnesium) for manganese."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! السلسلة بتبدأ بالـ Sc (21). و21 + 4 = 25، وده الـ manganese، Mn."},"b":{"why":"الـ Mg ده رمز الـ magnesium، وده عنصر تاني خالص؛ العنصر اللي الـ atomic number بتاعه 25 هو الـ manganese.","feedback":"الفكرة الغلط: الخلط بين رمز الـ manganese (Mn) ورمز الـ magnesium (Mg)."},"c":{"why":"بالترتيب: Sc 21, Ti 22, V 23, Cr 24، يعني الـ Cr هو 21 + 3، مش 21 + 4.","feedback":"الفكرة الغلط: تبديل ترتيب الـ Cr والـ Mn."},"d":{"why":"السلسلة بتبدأ بالـ scandium (21)، مش بالـ titanium؛ لو بدأت من الـ titanium هتوصل لـ 22 + 4 = 26، وده الـ Fe.","feedback":"الفكرة الغلط: إن الـ scandium مش من السلسلة، فالسلسلة بتبدأ من الـ titanium (22 + 4 = 26)."}},"explanation":"الخطوة 1: أول عنصر في الـ first transition series هو الـ scandium، $_{21}$Sc. الخطوة 2: 21 + 4 = 25. بالترتيب: Sc 21, Ti 22, V 23, Cr 24, Mn 25, Fe 26, Co 27, Ni 28, Cu 29, Zn 30. يبقى X هو الـ manganese، Mn. أشهر الغلطات: إنك تبدأ السلسلة من الـ Ti (فتطلع Fe)، أو تبدّل الـ Cr والـ Mn، أو تكتب Mg (الـ magnesium) بدل الـ manganese."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":59,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series","section_title":"The First Transition Series","section_path":["Transition Elements","The First Transition Series"],"relation":"based_on"}]},{"id":"chem-s3-en.question-phys.waves-light-1","kind":"question","version":1,"ord":116,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"phys.waves-light","concepts":[{"concept_id":"phys.waves-light","role":"primary"}],"title":"chem-s3-en.question-phys.waves-light-1","payload":{"stem":"What is the wavelength of a wave?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"The distance between two neighbouring crests","correct":true},{"id":"b","text":"The height of a crest above the middle line","correct":false},{"id":"c","text":"The number of waves that pass a point each second","correct":false},{"id":"d","text":"The time one wave takes to pass a point","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance, 2-Titanium (TiO2 and UV), p.5","difficulty":1,"concept_ids":["phys.waves-light"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! One wavelength is the length of one full wave, from crest to crest."},"b":{"why":"That is how tall the wave is: the amplitude. Wavelength is a length along the direction the wave travels, from one crest to the next.","feedback":"Misconception: Wavelength is the height of the wave (confusing it with amplitude)."},"c":{"why":"Counting waves per second gives a different quantity: the frequency.","feedback":"Misconception: Wavelength and frequency are the same thing."},"d":{"why":"Wavelength is measured in metres or nanometres, not seconds: it is a distance, not a time.","feedback":"Misconception: Wavelength is a time."}},"explanation":"Wavelength is the distance between two neighbouring crests (or two neighbouring troughs): the length of one full wave. Its unit is a unit of length, such as the metre or the nanometre (nm). The height of a crest is the amplitude, not the wavelength. The number of waves that pass a point each second is the frequency. Light travels as waves that carry energy, and light waves differ in wavelength and frequency."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ wavelength هي طول wave واحدة كاملة، من crest للـ crest اللي بعدها."},"b":{"why":"ده ارتفاع الـ wave: الـ amplitude. إنما الـ wavelength طول على امتداد الاتجاه اللي الـ wave ماشية فيه، من crest للـ crest اللي بعدها.","feedback":"الفكرة الغلط: إن الـ wavelength هي ارتفاع الـ wave (لخبطة بينها وبين الـ amplitude)."},"c":{"why":"لما تعدّ الـ waves اللي بتعدّي في الثانية، بتطلع بكمية تانية خالص: الـ frequency.","feedback":"الفكرة الغلط: إن الـ wavelength والـ frequency حاجة واحدة."},"d":{"why":"الـ wavelength بتتقاس بالـ metre أو بالـ nanometre، مش بالثواني: هي مسافة، مش زمن.","feedback":"الفكرة الغلط: إن الـ wavelength زمن."}},"explanation":"الـ wavelength هي المسافة بين اتنين crests جنب بعض (أو اتنين troughs جنب بعض)، يعني طول wave واحدة كاملة. وحدتها وحدة طول، زي الـ metre أو الـ nanometre (nm). ارتفاع الـ crest اسمه الـ amplitude، مش الـ wavelength. وعدد الـ waves اللي بتعدّي من نقطة كل ثانية اسمه الـ frequency. والضوء بيتنقل على شكل waves شايلة energy، والـ waves بتاعة الضوء بتختلف عن بعض في الـ wavelength والـ frequency."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":28,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.waves-light-2","kind":"question","version":1,"ord":117,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"phys.waves-light","concepts":[{"concept_id":"phys.waves-light","role":"primary"}],"title":"chem-s3-en.question-phys.waves-light-2","payload":{"stem":"Two light waves travel at the same speed. Wave P has a wavelength of 450 nm and wave Q has a wavelength of 650 nm. Which wave has the higher frequency?","tags":["diagnostic","prerequisite","data"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Wave P","correct":true},{"id":"b","text":"Wave Q","correct":false},{"id":"c","text":"Both have the same frequency, because they have the same speed","correct":false},{"id":"d","text":"We cannot tell without knowing how bright each light is","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance, 2-Titanium (TiO2 and UV), p.5","difficulty":2,"concept_ids":["phys.waves-light"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! Shorter waves fit more crests into each second."},"b":{"why":"Q's waves are longer. At the same speed, longer waves pass a point less often each second, so Q's frequency is lower.","feedback":"Misconception: A longer wavelength means a higher frequency."},"c":{"why":"Same speed, yes. But the waves have different lengths, so different numbers of long and short waves pass a point each second.","feedback":"Misconception: All light has the same frequency because all light has the same speed."},"d":{"why":"Brightness is not needed here. The wavelength alone tells you how many waves pass each second at the same speed.","feedback":"Misconception: Frequency depends on brightness."}},"explanation":"Both waves move at the same speed, so in one second the same length of wave train passes a point. Shorter waves fit more crests into that length, so more of them pass each second. P has the shorter wavelength (450 nm < 650 nm), so P has the higher frequency. For light: the shorter the wavelength, the higher the frequency. Brightness does not decide the frequency."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ waves الأقصر بيعدّي منها crests أكتر في كل ثانية."},"b":{"why":"الـ waves بتاعة Q أطول. وبنفس السرعة، الـ waves الأطول بتعدّي من نقطة مرات أقل في الثانية، فالـ frequency بتاعة Q أقل.","feedback":"الفكرة الغلط: إن الـ wavelength الأطول معناها frequency أعلى."},"c":{"why":"نفس السرعة، أيوه. لكن الـ waves أطوالها مختلفة، فعدد الـ waves الطويلة اللي بتعدّي من نقطة في الثانية بيختلف عن عدد القصيرة.","feedback":"الفكرة الغلط: إن الضوء كله ليه نفس الـ frequency عشان الضوء كله ليه نفس السرعة."},"d":{"why":"السطوع مش محتاجينه هنا. الـ wavelength لوحدها بتقولك كام wave بتعدّي في الثانية لما السرعة واحدة.","feedback":"الفكرة الغلط: إن الـ frequency بتعتمد على السطوع."}},"explanation":"الـ waves الاتنين ماشيين بنفس السرعة، يعني في الثانية الواحدة بيعدّي من النقطة نفس الطول من الـ waves. والـ waves الأقصر بيدخل منها crests أكتر في الطول ده، فبيعدّي منها عدد أكبر في الثانية. P هي اللي الـ wavelength بتاعتها أقصر (450 nm < 650 nm)، يبقى P هي اللي الـ frequency بتاعتها أعلى. بالنسبة للضوء: كل ما الـ wavelength تقصر، الـ frequency تعلى. والسطوع مش هو اللي بيحدد الـ frequency."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":29,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.em-spectrum-1","kind":"question","version":1,"ord":118,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"phys.em-spectrum","concepts":[{"concept_id":"phys.em-spectrum","role":"primary"}],"title":"chem-s3-en.question-phys.em-spectrum-1","payload":{"stem":"Which of the following rays has the highest penetrating power?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"Gamma rays","correct":true},{"id":"b","text":"Ultraviolet rays","correct":false},{"id":"c","text":"X-rays","correct":false},{"id":"d","text":"Infrared rays","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance: TiO2 and UV (p.5), cobalt-60 gamma rays (p.7), ZnS X-ray screens (p.8)","difficulty":1,"concept_ids":["phys.em-spectrum"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! Gamma rays have the most energy in the electromagnetic family, and the highest penetrating power."},"b":{"why":"UV can burn the skin, but it hardly passes through it. X-rays and gamma rays carry more energy than UV.","feedback":"Misconception: UV rays are the strongest because they burn the skin."},"c":{"why":"X-rays do pass through soft tissue, but gamma rays have an even shorter wavelength and more energy.","feedback":"Misconception: X-rays are the most penetrating because they pass through the body in medical images."},"d":{"why":"You feel infrared as heat, but it carries less energy than visible light, so its penetrating power is low.","feedback":"Misconception: Infrared (heat) rays are the most powerful because we can feel them."}},"explanation":"The electromagnetic family in order of increasing energy: radio waves, microwaves, infrared, visible light, ultraviolet (UV), X-rays, gamma rays. As the wavelength gets shorter, the energy increases. At the high-energy end, the penetrating power also rises from UV to X-rays to gamma rays. So gamma rays have the highest penetrating power. Chapter 1 uses this: cobalt-60 produces gamma rays, which have high penetrating power. So they are used to detect cracks and welding connections in industrial products."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ gamma rays فيها أعلى energy في العيلة الـ electromagnetic، وعندها أعلى penetrating power."},"b":{"why":"الـ UV ممكن تحرق الجلد، لكنها بالعافية بتعدّي منه. والـ X-rays والـ gamma rays شايلين energy أكتر من الـ UV.","feedback":"الفكرة الغلط: إن الـ UV rays هي الأقوى عشان بتحرق الجلد."},"c":{"why":"الـ X-rays فعلًا بتعدّي من الأنسجة الطرية، لكن الـ gamma rays الـ wavelength بتاعتها أقصر كمان والـ energy بتاعتها أكتر.","feedback":"الفكرة الغلط: إن الـ X-rays هي الأعلى في الـ penetrating power عشان بتعدّي من الجسم في صور الأشعة."},"d":{"why":"إنت بتحس بالـ infrared على إنه حرارة، لكنه شايل energy أقل من الـ visible light، فالـ penetrating power بتاعته واطية.","feedback":"الفكرة الغلط: إن الـ infrared (أشعة الحرارة) هي الأقوى عشان إحنا بنحس بيها."}},"explanation":"ترتيب العيلة الـ electromagnetic حسب زيادة الـ energy: radio waves، microwaves، infrared، visible light، ultraviolet (UV)، X-rays، gamma rays. كل ما الـ wavelength تقصر، الـ energy تزيد. وعند طرف الـ energy العالية، الـ penetrating power كمان بتزيد من الـ UV للـ X-rays للـ gamma rays. عشان كده الـ gamma rays هي اللي عندها أعلى penetrating power. والفصل الأول بيستخدم الفكرة دي: الـ cobalt-60 بيطلّع gamma rays عندها penetrating power عالية، فبنستخدمها في الكشف عن الشروخ ووصلات اللحام في المنتجات الصناعية."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":30,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.em-spectrum-2","kind":"question","version":1,"ord":119,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"phys.em-spectrum","concepts":[{"concept_id":"phys.em-spectrum","role":"primary"}],"title":"chem-s3-en.question-phys.em-spectrum-2","payload":{"stem":"Four rays W, X, Y and Z belong to the electromagnetic family. Their wavelengths are:\nW: 500 nm\nX: 0.01 nm\nY: 10 000 nm\nZ: 200 nm\nArrange them in ascending order of energy (lowest energy first).","tags":["diagnostic","prerequisite","data","arrange"],"type":"order","bloom":"apply","answer":["y","w","z","x"],"choices":[{"id":"y","text":"Ray Y (10 000 nm)"},{"id":"w","text":"Ray W (500 nm)"},{"id":"z","text":"Ray Z (200 nm)"},{"id":"x","text":"Ray X (0.01 nm)"}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance: TiO2 and UV (p.5), cobalt-60 gamma rays (p.7), ZnS X-ray screens (p.8)","difficulty":2,"concept_ids":["phys.em-spectrum"],"est_seconds":60},"layer":{"choices":{"w":{"why":"W's wave is shorter than Y's but longer than Z's and X's, so its energy is between theirs."},"x":{"why":"X has by far the shortest wavelength of the four, so it carries the most energy."},"y":{"why":"Y has the longest wavelength of the four, and a long wave carries little energy."},"z":{"why":"A shorter wave means more energy: Z's wave is shorter than W's and Y's but longer than X's."}},"explanation":"Rule: in the electromagnetic family, the shorter the wavelength, the higher the energy. So arrange from the longest wavelength to the shortest: Y (10 000 nm) < W (500 nm) < Z (200 nm) < X (0.01 nm). Y is infrared, W is visible light, Z is ultraviolet and X is in the X-ray range. Common mistake: putting the biggest wavelength number last. A bigger wavelength means LESS energy, not more."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"w":{"why":"الـ wave بتاعة W أقصر من بتاعة Y لكن أطول من بتاعة Z و X، فالـ energy بتاعتها في النص بينهم."},"x":{"why":"الـ X عندها أقصر wavelength في الأربعة بفرق كبير، فهي شايلة أكبر energy."},"y":{"why":"الـ Y عندها أطول wavelength في الأربعة، والـ wave الطويلة بتشيل energy قليلة."},"z":{"why":"الـ wave الأقصر معناها energy أكتر: الـ wave بتاعة Z أقصر من بتاعة W و Y، لكن أطول من بتاعة X."}},"explanation":"القاعدة: في العيلة الـ electromagnetic، كل ما الـ wavelength تقصر، الـ energy تعلى. يبقى رتّبهم من أطول wavelength لأقصر واحدة: Y (10 000 nm) < W (500 nm) < Z (200 nm) < X (0.01 nm). الـ Y دي infrared، والـ W دي visible light، والـ Z دي ultraviolet، والـ X واقعة في نطاق الـ X-ray. غلطة بتتكرر: إنك تحط أكبر رقم wavelength في الآخر. wavelength أكبر معناها energy أقل، مش أكتر."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":31,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.valency-formulas-1","kind":"question","version":1,"ord":120,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.valency-formulas","concepts":[{"concept_id":"chem.valency-formulas","role":"primary"}],"title":"chem-s3-en.question-chem.valency-formulas-1","payload":{"stem":"Titanium dioxide, $TiO_2$, can also be named titanium (IV) oxide. What does the Roman numeral (IV) in this name tell you?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"The valency of titanium in this compound is 4","correct":true},{"id":"b","text":"The formula contains 4 oxygen atoms","correct":false},{"id":"c","text":"The formula contains 4 titanium atoms","correct":false},{"id":"d","text":"Oxygen has a valency of 4 in this compound","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance (compound formulas, e.g. TiO2 p.5)","difficulty":1,"concept_ids":["chem.valency-formulas"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! The Roman numeral gives the metal's valency."},"b":{"why":"$TiO_2$ has 2 O atoms, which does not match the numeral IV.","feedback":"Misconception: The Roman numeral counts the atoms of the other element."},"c":{"why":"$TiO_2$ has only 1 Ti atom. The number after the metal's name gives its valency, not a count of atoms.","feedback":"Misconception: The Roman numeral is the number of atoms of the metal."},"d":{"why":"The numeral is written right after 'titanium', not after 'oxide'. Oxygen keeps its usual valency of 2.","feedback":"Misconception: The Roman numeral gives the valency of the non-metal in the name."}},"explanation":"A Roman numeral after a metal's name gives the valency of the metal in that compound. In titanium (IV) oxide, Ti has valency 4 and O keeps its usual valency of 2. Swap the valencies: $Ti_2O_4$. Simplify by 2: $TiO_2$. So the numeral is not a count of atoms: $TiO_2$ has 1 Ti atom and 2 O atoms. Some elements have more than one valency, which is why the numeral is needed. $TiO_2$ is the compound used in sun protection cosmetics (Ch.1 p.5)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الرقم الروماني بيقولك الـ valency بتاعة الـ metal."},"b":{"why":"الـ $TiO_2$ فيه ذرتين O بس، فالرقم ده مش هو الرقم الروماني.","feedback":"الفكرة الغلط: إن الرقم الروماني بيعدّ ذرات العنصر التاني."},"c":{"why":"الـ $TiO_2$ فيه ذرة Ti واحدة بس. والرقم اللي بعد اسم الـ metal بيدّي حاجة تانية غير عدد الذرات.","feedback":"الفكرة الغلط: إن الرقم الروماني هو عدد ذرات الـ metal."},"d":{"why":"الرقم مكتوب بعد «titanium» على طول، مش بعد «oxide». والـ oxygen الـ valency المعتادة بتاعته 2.","feedback":"الفكرة الغلط: إن الرقم الروماني بيدّي الـ valency بتاعة الـ non-metal اللي في الاسم."}},"explanation":"الرقم الروماني اللي بعد اسم الـ metal بيدّيك الـ valency بتاعة الـ metal في الـ compound ده. في الـ titanium (IV) oxide، الـ Ti الـ valency بتاعته 4، والـ O فاضل على الـ valency المعتادة بتاعته، 2. بدّل الـ valencies: $Ti_2O_4$. اختصر على 2: $TiO_2$. يعني الرقم الروماني مش عدد ذرات: $TiO_2$ فيه ذرة Ti واحدة وذرتين O. وفيه عناصر ليها أكتر من valency، وعشان كده محتاجين الرقم ده. والـ $TiO_2$ هو الـ compound اللي بيتستخدم في مستحضرات التجميل اللي بتحمي من الشمس (الفصل الأول، ص 5)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":32,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-chem.valency-formulas-2","kind":"question","version":1,"ord":121,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.valency-formulas","concepts":[{"concept_id":"chem.valency-formulas","role":"primary"}],"title":"chem-s3-en.question-chem.valency-formulas-2","payload":{"stem":"Which is the correct formula of iron (III) sulphate? (The sulphate group, $SO_4$, has valency 2.)","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$Fe_2(SO_4)_3$","correct":true},{"id":"b","text":"$Fe_3(SO_4)_2$","correct":false},{"id":"c","text":"$FeSO_4$","correct":false},{"id":"d","text":"$Fe_2SO_4$","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance (compound formulas, e.g. V2O5, CuSO4 pp.6-7)","difficulty":2,"concept_ids":["chem.valency-formulas"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! 2 iron atoms and 3 sulphate groups."},"b":{"why":"Here each valency stayed on its own part. In the swap, iron's valency goes to the sulphate group ($SO_4$).","feedback":"Misconception: Each part keeps its own valency as its number (no swap)."},"c":{"why":"This formula fits iron of valency 2, but the Roman numeral III gives iron a valency of 3 here.","feedback":"Misconception: Ignoring the Roman numeral (this is iron (II) sulphate)."},"d":{"why":"Iron's valency must go to the group, so the sulphate group is taken more than once. A group taken more than once goes in brackets.","feedback":"Misconception: Only the metal's number changes; the group is always taken once."}},"explanation":"Steps: (1) symbols: Fe and $SO_4$. (2) valencies: Fe = 3 (from the Roman numeral III), $SO_4$ = 2. (3) swap: 2 Fe and 3 $SO_4$ groups. (4) 2 and 3 cannot be simplified. The group is taken 3 times, so it goes in brackets: $Fe_2(SO_4)_3$. Check: 2 × 3 = 6 and 3 × 2 = 6, so the valencies balance."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! ذرتين iron و 3 sulphate groups."},"b":{"why":"هنا كل valency فضلت على الجزء بتاعها. في التبديل، الـ valency بتاعة الـ iron بتروح للـ $SO_4$ group.","feedback":"الفكرة الغلط: إن كل جزء بياخد الـ valency بتاعته هو كعدد ليه (من غير تبديل)."},"c":{"why":"الـ formula دي تنفع لـ iron الـ valency بتاعته 2، لكن الرقم الروماني في الاسم III، يعني الـ valency هنا 3.","feedback":"الفكرة الغلط: إنك تتجاهل الرقم الروماني (الـ formula دي بتاعة iron (II) sulphate)."},"d":{"why":"هنا فيه sulphate group واحدة بس، والـ valency بتاعة الـ iron لازم تروح للـ group. ولما الـ group تتاخد أكتر من مرة، بتتحط بين أقواس.","feedback":"الفكرة الغلط: إن رقم الـ metal هو اللي بيتغير لوحده، والـ group بتتاخد مرة واحدة على طول."}},"explanation":"الخطوات: (1) الرموز: Fe و $SO_4$. (2) الـ valencies: Fe = 3 (من الرقم الروماني III)، و $SO_4$ = 2. (3) التبديل: 2 Fe و 3 groups من $SO_4$. (4) 2 و 3 مينفعش يتختصروا. والـ group متاخدة 3 مرات، فبتتحط بين أقواس: $Fe_2(SO_4)_3$. اتأكد بنفسك: 2 × 3 = 6 و 3 × 2 = 6، يعني الـ valencies متوازنة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":33,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-chem.equation-balancing-1","kind":"question","version":1,"ord":122,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.equation-balancing","concepts":[{"concept_id":"chem.equation-balancing","role":"primary"}],"title":"chem-s3-en.question-chem.equation-balancing-1","payload":{"stem":"Look at the balanced equation $\\ce{3Fe + 2O2 -> Fe3O4}$. How many oxygen atoms are on the left side?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"4","correct":true},{"id":"b","text":"2","correct":false},{"id":"c","text":"3","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); needed for every equation in Ch.1 (e.g. iron oxides, Haber-Bosch)","difficulty":1,"concept_ids":["chem.equation-balancing"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! 2 molecules × 2 atoms = 4, the same number as in $Fe_3O_4$."},"b":{"why":"You counted one $O_2$ molecule. The coefficient 2 in front of it means two molecules, each with 2 O atoms.","feedback":"Misconception: Ignoring the coefficient; counting only the subscript."},"c":{"why":"The 3 belongs to Fe only. The coefficient of $O_2$ is 2, and each $O_2$ has 2 atoms.","feedback":"Misconception: A coefficient applies to the whole side of the equation."}},"explanation":"A coefficient multiplies the whole formula after it; a subscript counts the atoms inside one molecule. $2O_2$ means 2 molecules × 2 O atoms = 4 O atoms. The right side, $Fe_3O_4$, also has 4 O atoms, and Fe is 3 on each side, so the equation is balanced. $Fe_3O_4$ is the magnetic iron oxide you meet later in Chapter 1."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! 2 molecules × 2 ذرات = 4، نفس العدد اللي في الـ $Fe_3O_4$."},"b":{"why":"إنت عدّيت $O_2$ molecule واحد. الـ coefficient 2 اللي قدامه بيضرب الـ molecule في 2.","feedback":"الفكرة الغلط: إنك تتجاهل الـ coefficient وتعدّ الـ subscript لوحده."},"c":{"why":"الـ 3 ده تبع الـ Fe لوحده. الـ $O_2$ قدامه الـ coefficient 2، وكل $O_2$ فيه ذرتين.","feedback":"الفكرة الغلط: إن الـ coefficient بيتطبق على ناحية الـ equation بالكامل."}},"explanation":"الـ coefficient بيضرب في الـ formula اللي بعده بالكامل؛ أما الـ subscript فبيعدّ الذرات اللي جوه molecule واحد. يعني $2O_2$ معناها 2 molecules × 2 ذرات O = 4 ذرات O. والناحية اليمين، $Fe_3O_4$، فيها برضه 4 ذرات O، والـ Fe عدده 3 في الناحيتين، يبقى الـ equation دي balanced. والـ $Fe_3O_4$ ده الـ magnetic iron oxide اللي هتقابله بعدين في الفصل الأول."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":34,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.equation-balancing-2","kind":"question","version":1,"ord":123,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.equation-balancing","concepts":[{"concept_id":"chem.equation-balancing","role":"primary"}],"title":"chem-s3-en.question-chem.equation-balancing-2","payload":{"stem":"Which coefficients balance this equation?\n$\\ce{Fe2O3 + CO -> Fe + CO2}$\n(in the order $Fe_2O_3$, CO, Fe, $CO_2$)","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"1, 3, 2, 3","correct":true},{"id":"b","text":"1, 1, 2, 1","correct":false},{"id":"c","text":"1, 2, 2, 2","correct":false},{"id":"d","text":"2, 3, 4, 3","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); needed for every equation in Ch.1 (e.g. reduction of iron oxides)","difficulty":3,"concept_ids":["chem.equation-balancing"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Correct! Fe 2 = 2, C 3 = 3, O 6 = 6."},"b":{"why":"Fe is balanced now, but O is not: 3 + 1 on the left, 2 on the right.","feedback":"Misconception: Balancing one element and stopping."},"c":{"why":"O is still not balanced: 3 + 2 on the left, 4 on the right. The coefficients of CO and $CO_2$ must change.","feedback":"Misconception: Not recounting every atom at the end."},"d":{"why":"Fe is 4 = 4, but O is not balanced: 6 + 3 on the left, 6 on the right.","feedback":"Misconception: Doubling one formula without rechecking oxygen."}},"explanation":"Change coefficients only, never subscripts. Fe: $Fe_2O_3$ has 2 Fe, so put 2 before Fe. O: each CO takes one O and becomes $CO_2$. $Fe_2O_3$ has 3 O, so 3 CO are needed, giving 3 $CO_2$. Check every atom: Fe 2 = 2; C 3 = 3; O 3 + 3 = 6 on the left and 3 × 2 = 6 on the right. $\\ce{Fe2O3 + 3CO -> 2Fe + 3CO2}$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ Fe: 2 = 2، والـ C: 3 = 3، والـ O: 6 = 6."},"b":{"why":"الـ Fe اتوزن، لكن ذرات الـ O: 3 + 1 على الشمال، و2 على اليمين، ودول مش متساويين.","feedback":"الفكرة الغلط: إنك توزن عنصر واحد وتقف لحد كده."},"c":{"why":"ذرات الـ O: 3 + 2 على الشمال، و4 على اليمين، يعني الـ oxygen لسه مش متوازن، والـ coefficients بتوع الـ CO والـ $CO_2$ لازم تتغيّر.","feedback":"الفكرة الغلط: إنك ماتعيدش عدّ الذرات عنصر عنصر في الآخر."},"d":{"why":"الـ Fe بقى 4 = 4، لكن الـ O: 6 + 3 على الشمال، و6 على اليمين، ودول مش متساويين.","feedback":"الفكرة الغلط: إنك تضاعف formula واحدة من غير ما ترجع تراجع الـ oxygen."}},"explanation":"غيّر الـ coefficients لوحدها، وماتغيرش الـ subscripts أبدًا. الـ Fe: الـ $Fe_2O_3$ فيه 2 Fe، فحط 2 قدام الـ Fe. الـ O: الـ CO الواحد بياخد ذرة O واحدة ويتحول لـ $CO_2$. والـ $Fe_2O_3$ فيه 3 O، يبقى محتاجين 3 CO، ودول بيدّوا 3 $CO_2$. راجع الذرات عنصر عنصر: الـ Fe 2 = 2؛ الـ C 3 = 3؛ الـ O: 3 + 3 = 6 على الشمال و3 × 2 = 6 على اليمين. $\\ce{Fe2O3 + 3CO -> 2Fe + 3CO2}$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":35,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.catalyst-1","kind":"question","version":1,"ord":124,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.catalyst","concepts":[{"concept_id":"chem.catalyst","role":"primary"}],"title":"chem-s3-en.question-chem.catalyst-1","payload":{"stem":"Which statement describes a catalyst?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"It speeds up a chemical reaction and is not used up by it.","correct":true},{"id":"b","text":"It speeds up a chemical reaction and is used up as the reaction goes on.","correct":false,"misconception_id":"chem.catalyst.mc1"},{"id":"c","text":"It increases the amount of product made from the same reactants.","correct":false},{"id":"d","text":"It is one of the reactants, so it is written on the left of the arrow.","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); needed for Ch.1 economic importance (V2O5, iron and nickel catalysts pp.6-7) and catalytic activity p.15","difficulty":1,"concept_ids":["chem.catalyst"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! It is unchanged at the end of the reaction."},"b":{"why":"A catalyst is not used up: a factory can use the same catalyst again and again, and its mass at the end is the same as at the start.","feedback":"Misconception: The catalyst is consumed in the reaction."},"c":{"why":"A catalyst changes how fast the product forms. It does not change how much product the reactants can give.","feedback":"Misconception: A catalyst gives more product."},"d":{"why":"A catalyst is not a reactant: in an equation it is written over the arrow, not among the reactants.","feedback":"Misconception: A catalyst is a reactant."}},"explanation":"A catalyst speeds up a chemical reaction without being used up: its mass and chemical nature are the same at the end. It does not change the amount of product; it only helps the reaction reach it faster. In an equation, the catalyst is written over the arrow, not among the reactants."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ catalyst بيفضل زي ما هو من غير تغيير في آخر الـ reaction."},"b":{"why":"لو كان بيتستهلك، المصنع ماكانش هيقدر يستخدم نفس الـ catalyst مرة ورا مرة، وكتلته كانت هتقل في الآخر. لكن كتلته بتفضل زي ما هي.","feedback":"الفكرة الغلط: إن الـ catalyst بيتستهلك في الـ reaction."},"c":{"why":"الـ catalyst بيغيّر سرعة تكوين الـ product، لكن مابيغيّرش كمية الـ product اللي الـ reactants تقدر تدّيها.","feedback":"الفكرة الغلط: إن الـ catalyst بيدّي product أكتر."},"d":{"why":"الـ catalyst مش بيتكتب وسط الـ reactants؛ بيتكتب فوق السهم في الـ equation.","feedback":"الفكرة الغلط: إن الـ catalyst واحد من الـ reactants."}},"explanation":"الـ catalyst بيسرّع الـ chemical reaction من غير ما يتستهلك: كتلته وطبيعته الكيميائية بيفضلوا زي ما هما في الآخر. ومابيغيّرش كمية الـ product؛ دوره إنه يخلّي الـ reaction يوصل لها أسرع. وفي الـ equation، الـ catalyst بيتكتب فوق السهم، مش وسط الـ reactants."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":36,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":65,"page_to":65,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.catalyst-2","kind":"question","version":1,"ord":125,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.catalyst","concepts":[{"concept_id":"chem.catalyst","role":"primary"}],"title":"chem-s3-en.question-chem.catalyst-2","payload":{"stem":"A reaction gives off a gas. A student runs it twice with the same amounts of reactants.\nWithout powder X: 50 mL of gas form in 10 minutes.\nWith 1.0 g of powder X: 50 mL of gas form in 1 minute.\nAt the end, she dries and weighs X: its mass is still 1.0 g.\nWhat is X in this reaction?","tags":["diagnostic","prerequisite","data"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"A catalyst","correct":true},{"id":"b","text":"A reactant, because it changed the speed of the reaction","correct":false},{"id":"c","text":"A product of the reaction","correct":false},{"id":"d","text":"A substance with no effect on the reaction","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); needed for Ch.1 economic importance (V2O5, iron and nickel catalysts pp.6-7) and catalytic activity p.15","difficulty":2,"concept_ids":["chem.catalyst"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! It sped up the reaction and was not used up."},"b":{"why":"If X had reacted, part of it would be used up. All 1.0 g of X is still there at the end, so X did not react.","feedback":"Misconception: Anything that changes a reaction's speed is a reactant."},"c":{"why":"X was added before the reaction started, and a product cannot be there at the start.","feedback":"Misconception: A substance found at the end is a product."},"d":{"why":"Compare the times: with X, the same 50 mL of gas formed in 1 minute instead of 10. So X made a big difference.","feedback":"Misconception: A substance that is not used up has no effect."}},"explanation":"Two pieces of data decide. (1) With X, the same volume of gas forms 10 times faster, so X speeds up the reaction. (2) X's mass is the same at the end, so X is not used up. A substance that speeds up a reaction without being used up is a catalyst. It is written over the arrow in the equation, not among the reactants."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! سرّع الـ reaction ومااتستهلكش."},"b":{"why":"لو الـ X كان اتفاعل، الـ 1.0 g ماكانتش هتفضل كاملة في الآخر. كتلته فضلت هي هي، يبقى مااتستهلكش.","feedback":"الفكرة الغلط: إن أي حاجة بتغيّر سرعة الـ reaction تبقى reactant."},"c":{"why":"الـ X اتضاف قبل ما الـ reaction يبدأ، والـ product مابيبقاش موجود من البداية.","feedback":"الفكرة الغلط: إن المادة اللي بتلاقيها في الآخر تبقى product."},"d":{"why":"مع الـ X نفس حجم الغاز اتكوّن في دقيقة بدل 10 دقايق، يعني الـ X عمل فرق واضح.","feedback":"الفكرة الغلط: إن المادة اللي مابتتستهلكش مالهاش تأثير."}},"explanation":"فيه معلومتين من البيانات هما اللي بيحسموا. (1) مع الـ X، نفس حجم الغاز بيتكوّن أسرع 10 مرات، يبقى الـ X بيسرّع الـ reaction. (2) كتلة الـ X في الآخر هي هي، يبقى الـ X مااتستهلكش. والمادة اللي بتسرّع الـ reaction من غير ما تتستهلك هي الـ catalyst. والـ catalyst بيتكتب فوق السهم في الـ equation، مش وسط الـ reactants."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":37,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":65,"page_to":65,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.metal-properties-1","kind":"question","version":1,"ord":126,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.metal-properties","concepts":[{"concept_id":"chem.metal-properties","role":"primary"}],"title":"chem-s3-en.question-chem.metal-properties-1","payload":{"stem":"Which set of properties belongs to most metals?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"Shiny, good conductors of heat and electricity, malleable","correct":true},{"id":"b","text":"Shiny, poor conductors of heat and electricity, brittle","correct":false},{"id":"c","text":"Dull, good conductors of heat and electricity, brittle","correct":false},{"id":"d","text":"Dull, poor conductors of heat and electricity, malleable","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance pp.5-7 (uses chosen by property; brittle manganese p.6)","difficulty":1,"concept_ids":["chem.metal-properties"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! These are typical metal properties."},"b":{"why":"Shine fits, but a metal spoon left in hot tea quickly gets hot: metals are good conductors.","feedback":"Misconception: Shiny solids are metals, but metals do not conduct well."},"c":{"why":"A new coin is shiny, and an iron sheet can be hammered flat without breaking. Metals are usually shiny and malleable, not dull and brittle.","feedback":"Misconception: Metals are dull and break when hammered."},"d":{"why":"This mixes metal and non-metal properties. Metal is used inside electric wires because metals are good conductors of electricity.","feedback":"Misconception: Metals are poor conductors."}},"explanation":"Most metals are shiny, good conductors of heat and electricity, malleable (can be hammered into sheets) and ductile (can be drawn into wires), and mostly solid with high melting points. Most non-metals are dull, poor conductors and brittle when solid. Note the word 'most'. Manganese, for example, is a brittle metal. That is why Chapter 1 says it is never used as a pure metal."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! دي صفات الـ metals المعتادة."},"b":{"why":"الـ shiny ماشية. لكن المعلقة الـ metal اللي سايبها في شاي سخن بتسخن بسرعة لما تلمسها، يعني الـ metals بتوصّل الحرارة كويس.","feedback":"الفكرة الغلط: إن الحاجات الـ solid اللي shiny تبقى metals، لكن الـ metals مابتوصّلش كويس."},"c":{"why":"العملة الجديدة بتلمع، ولوح الـ iron بيتطرّق ويتفرد من غير ما يتكسر. يعني الـ metals عادةً مش dull ومش brittle.","feedback":"الفكرة الغلط: إن الـ metals بتبقى dull وبتتكسر لما تتطرّق."},"d":{"why":"الاختيار ده بيخلط صفات الـ metals بصفات الـ non-metals. الـ metals هي اللي بتتستخدم جوه أسلاك الكهربا عشان بتوصّل الكهربا كويس.","feedback":"الفكرة الغلط: إن الـ metals بتبقى poor conductors."}},"explanation":"أغلب الـ metals بتبقى shiny، و good conductors of heat and electricity، و malleable (ينفع تتطرّق لشرايح) و ductile (ينفع تتسحب لأسلاك)، وأغلبها solid والـ melting points بتاعتها عالية. أما أغلب الـ non-metals فبتبقى dull و poor conductors و brittle وهي solid. خلّي بالك من كلمة 'most' (أغلب). الـ manganese مثلًا metal لكنه brittle، وعشان كده الفصل الأول بيقول إنه مابيتستخدمش وهو metal نقي."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":38,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.properties","section_title":"Properties of Iron","section_path":["Transition Elements","Iron","Properties of Iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.metal-properties-2","kind":"question","version":1,"ord":127,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.metal-properties","concepts":[{"concept_id":"chem.metal-properties","role":"primary"}],"title":"chem-s3-en.question-chem.metal-properties-2","payload":{"stem":"A company makes the bottoms of cooking pans. The pan bottom must pass heat quickly from the flame to the food. Which property of the metal matters most for this job?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"It is a good conductor of heat","correct":true},{"id":"b","text":"It is ductile","correct":false},{"id":"c","text":"It is shiny","correct":false},{"id":"d","text":"It has a high melting point","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance pp.5-7 (uses chosen by property, e.g. copper in electric cables p.7)","difficulty":2,"concept_ids":["chem.metal-properties"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! The job is to pass heat, so heat conduction decides."},"b":{"why":"Ductile is about drawing wires, and a pan bottom does not need to be drawn into a wire.","feedback":"Misconception: Any metal property explains any use."},"c":{"why":"Shine is about how a metal looks. It says nothing about heat moving through the metal.","feedback":"Misconception: Shine helps a metal pass heat."},"d":{"why":"A high melting point stops the pan from melting, but it does not make heat move through the metal faster.","feedback":"Misconception: A high melting point is what makes heat pass quickly."}},"explanation":"Match the use to the property it needs. The pan's job is to carry heat from the flame to the food, so the key property is being a good conductor of heat. A high melting point is also useful (the pan must not melt), but it does not make heat pass quickly. Ductile and shiny do not help this job. Chapter 1 uses the same thinking: copper is used in electric cables because it is a good conductor of electricity."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! شغلانة قاع الحلة إنه ينقل الحرارة، يعني توصيل الحرارة هو اللي بيحسم."},"b":{"why":"الـ ductile ليها علاقة بسحب الأسلاك، وقاع الحلة مش محتاج يتسحب لسلك.","feedback":"الفكرة الغلط: إن أي صفة من صفات الـ metal تنفع تفسّر أي استخدام."},"c":{"why":"اللمعة بتخص شكل الـ metal من برّه، ومالهاش علاقة بحركة الحرارة جوه الـ metal.","feedback":"الفكرة الغلط: إن اللمعة بتساعد الـ metal ينقل الحرارة."},"d":{"why":"الـ high melting point بتمنع الحلة إنها تسيح، لكن مش بتخلي الحرارة تتحرك في الـ metal أسرع.","feedback":"الفكرة الغلط: إن الـ high melting point هي اللي بتخلي الحرارة تعدّي بسرعة."}},"explanation":"طابق الاستخدام بالصفة اللي محتاجها. شغلانة الحلة إنها تنقل الحرارة من النار للأكل، يعني الصفة الأساسية إنها تكون good conductor of heat. الـ high melting point مفيدة برضه (الحلة لازم ماتسيحش)، لكنها مش بتخلي الحرارة تعدّي بسرعة. والـ ductile والـ shiny مش بيفيدوا في الشغلانة دي. والفصل الأول بيفكّر بنفس الطريقة: الـ copper بيتستخدم في كابلات الكهربا عشان هو good conductor of electricity."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":39,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.acids-bases-salts-1","kind":"question","version":2,"ord":128,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.acids-bases-salts","concepts":[{"concept_id":"chem.acids-bases-salts","role":"primary"}],"title":"chem-s3-en.question-chem.acids-bases-salts-1","payload":{"stem":"Which of the following substances is an alkali?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"$\\ce{KOH}$","correct":true},{"id":"b","text":"$\\ce{HNO3}$","correct":false},{"id":"c","text":"$\\ce{KNO3}$","correct":false},{"id":"d","text":"$\\ce{Cu(OH)2}$","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance (salts named on pp.6-8, e.g. CuSO4, ZnS)","difficulty":1,"concept_ids":["chem.acids-bases-salts"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! $\\ce{KOH}$ gives hydroxide ions, $\\ce{OH-}$, in water."},"b":{"why":"This compound gives $\\ce{H+}$ ions in water, not $\\ce{OH-}$ ions, so it is an acid.","feedback":"Misconception: Any compound with H and O is a base."},"c":{"why":"This compound has a metal but no OH group: it is the product of an acid and a base, a salt.","feedback":"Misconception: Every compound that contains a metal is a base."},"d":{"why":"This compound has OH groups, so it is a base. But it does not dissolve in water, and a base must dissolve in water to be an alkali.","feedback":"Misconception: Every base is an alkali."}},"explanation":"An alkali is a base that dissolves in water, giving hydroxide ions ($\\ce{OH-}$). $\\ce{KOH}$ (potassium hydroxide) contains the OH group and dissolves in water, so it is an alkali. Its formula has an H, but it gives $\\ce{OH-}$ ions, not $\\ce{H+}$ ions. $\\ce{HNO3}$ is an acid: it gives $\\ce{H+}$ ions in water. $\\ce{Cu(OH)2}$ is a base, but it does not dissolve in water, so it is not an alkali. $\\ce{KNO3}$ is a salt: potassium replaced the hydrogen of nitric acid."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ $\\ce{KOH}$ بيدي hydroxide ions، $\\ce{OH-}$، في الماية."},"b":{"why":"الـ compound ده بيدي $\\ce{H+}$ ions في الماية، مش $\\ce{OH-}$، يعني هو acid.","feedback":"الفكرة الغلط: إن أي compound فيه H و O يبقى base."},"c":{"why":"الـ compound ده فيه metal، لكن مفيهوش OH group. ده salt: الناتج بتاع acid مع base.","feedback":"الفكرة الغلط: إن أي compound فيه metal يبقى base."},"d":{"why":"الـ compound ده فيه OH groups، يعني هو base. لكنه مش بيدوب في الماية، والـ base لازم يدوب في الماية عشان يبقى alkali.","feedback":"الفكرة الغلط: إن أي base يبقى alkali."}},"explanation":"الـ alkali هو base بيدوب في الماية ويدي hydroxide ions ($\\ce{OH-}$). الـ $\\ce{KOH}$ (potassium hydroxide) فيه الـ OH group وبيدوب في الماية، يعني هو alkali. صحيح الـ formula بتاعته فيها H، لكنه بيدي $\\ce{OH-}$ ions، مش $\\ce{H+}$ ions. أما الـ $\\ce{HNO3}$ فهو acid: بيدي $\\ce{H+}$ ions في الماية. والـ $\\ce{Cu(OH)2}$ ده base، لكنه مش بيدوب في الماية، فمش alkali. والـ $\\ce{KNO3}$ ده salt: الـ potassium خد مكان الـ hydrogen بتاع الـ nitric acid."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":40,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.acids-bases-salts-2","kind":"question","version":1,"ord":129,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.acids-bases-salts","concepts":[{"concept_id":"chem.acids-bases-salts","role":"primary"}],"title":"chem-s3-en.question-chem.acids-bases-salts-2","payload":{"stem":"Potassium hydroxide reacts with dilute sulphuric acid. What is the name of the salt formed?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Potassium sulphate","correct":true},{"id":"b","text":"Potassium sulphide","correct":false},{"id":"c","text":"Potassium chloride","correct":false},{"id":"d","text":"Potassium nitrate","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance (salts named on pp.6-8, e.g. CuSO4, ZnS)","difficulty":2,"concept_ids":["chem.acids-bases-salts"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! Sulphuric acid gives sulphates."},"b":{"why":"A sulphide has sulphur only, like ZnS. Sulphuric acid gives a group of sulphur and oxygen.","feedback":"Misconception: 'Sulphate' and 'sulphide' mean the same thing."},"c":{"why":"Chlorides come from hydrochloric acid, and that is not the acid used here.","feedback":"Misconception: Every salt is a chloride."},"d":{"why":"Nitrates contain the $NO_3$ group, and sulphuric acid does not contain that group.","feedback":"Misconception: Mixing up which acid gives which salt."}},"explanation":"Acid + base → salt + water. The salt takes its metal from the base (potassium) and its ending from the acid: sulphuric acid ($H_2SO_4$) gives sulphates. $\\ce{2KOH + H2SO4 -> K2SO4 + 2H2O}$. Careful: a sulphate ($SO_4$: sulphur and oxygen) is not a sulphide (sulphur only). Chapter 1 uses both: zinc sulphide, ZnS (X-ray screens), and copper (II) sulphate, $CuSO_4$ (insecticide and fungicide)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ sulphuric acid بيدي sulphates."},"b":{"why":"الـ sulphide فيه sulphur لوحده، زي الـ ZnS. والـ sulphuric acid بيدي group فيها sulphur و oxygen، مش sulphur لوحده.","feedback":"الفكرة الغلط: إن 'sulphate' و 'sulphide' معناهم واحد."},"c":{"why":"الـ chlorides مش بتيجي من الـ sulphuric acid، والـ sulphuric acid هو الـ acid المستخدم هنا.","feedback":"الفكرة الغلط: إن أي salt يبقى chloride."},"d":{"why":"الـ nitrates فيها الـ $NO_3$ group، والـ sulphuric acid مفيهوش الـ group دي.","feedback":"الفكرة الغلط: لخبطة في أنهي acid بيدي أنهي salt."}},"explanation":"القاعدة: acid + base → salt + water. الـ salt بياخد الـ metal بتاعه من الـ base (هنا الـ potassium)، وبياخد النهاية من الـ acid: الـ sulphuric acid ($H_2SO_4$) بيدي sulphates. $\\ce{2KOH + H2SO4 -> K2SO4 + 2H2O}$. خلّي بالك: الـ sulphate ($SO_4$: sulphur و oxygen) مش هو الـ sulphide (sulphur لوحده). والفصل الأول بيستخدم الاتنين: الـ zinc sulphide، ZnS (في شاشات الـ X-ray)، والـ copper (II) sulphate، $CuSO_4$ (كـ insecticide و fungicide)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":41,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.oxides-1","kind":"question","version":2,"ord":130,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.oxides","concepts":[{"concept_id":"chem.oxides","role":"primary"}],"title":"chem-s3-en.question-chem.oxides-1","payload":{"stem":"Which of the following oxides is an acidic oxide?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"$\\ce{NO2}$","correct":true},{"id":"b","text":"$\\ce{NiO}$","correct":false},{"id":"c","text":"$\\ce{CoO}$","correct":false},{"id":"d","text":"$\\ce{BaO}$","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance (oxides: TiO2, V2O5, Cr2O3, ZnO pp.5-8)","difficulty":1,"concept_ids":["chem.oxides"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! N is nitrogen, a non-metal."},"b":{"why":"Ni is the symbol of nickel, a metal, so NiO is a basic oxide.","feedback":"Misconception: Reading Ni (nickel) as N (nitrogen)."},"c":{"why":"Co is the symbol of cobalt, one element, and cobalt is a metal. So CoO is a basic oxide.","feedback":"Misconception: Oxides of transition elements are acidic / Co read as C + O."},"d":{"why":"Barium is in group 2, with calcium, and it is a metal. So BaO is a basic oxide.","feedback":"Misconception: Oxides of group 2 elements are acidic."}},"explanation":"Most non-metal oxides are acidic oxides: they dissolve in water to give acids. Most metal oxides are basic oxides: they react with acids to give a salt and water. $\\ce{NO2}$ is an oxide of nitrogen (N), a non-metal, so it is acidic. NiO (nickel), CoO (cobalt) and BaO (barium) are oxides of metals, so they are basic. Read symbols carefully: N is nitrogen but Ni is nickel; Co is cobalt, not carbon + oxygen."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ N ده nitrogen، وهو non-metal."},"b":{"why":"الـ Ni ده رمز الـ nickel، والـ nickel ده metal، فالـ oxide بتاعه basic.","feedback":"الفكرة الغلط: إنك تقرا Ni (nickel) على إنه N (nitrogen)."},"c":{"why":"الـ Co ده رمز الـ cobalt، عنصر واحد، والـ cobalt ده metal، فالـ oxide بتاعه basic.","feedback":"الفكرة الغلط: إن الـ oxides بتاعة الـ transition elements بتبقى acidic، أو إنك تقرا Co على إنه C + O."},"d":{"why":"الـ barium في الـ group 2، مع الـ calcium، وهو metal، فالـ oxide بتاعه basic.","feedback":"الفكرة الغلط: إن الـ oxides بتاعة عناصر الـ group 2 بتبقى acidic."}},"explanation":"أغلب الـ non-metal oxides بتبقى acidic oxides: بتدوب في الماية وتدي acids. وأغلب الـ metal oxides بتبقى basic oxides: بتتفاعل مع الـ acids وتدي salt و water. الـ $\\ce{NO2}$ ده oxide للـ nitrogen (N)، والـ nitrogen non-metal، يبقى الـ oxide ده acidic. أما الـ NiO (nickel) والـ CoO (cobalt) والـ BaO (barium) فدول oxides لـ metals، يبقوا basic. اقرا الرموز كويس: الـ N ده nitrogen لكن الـ Ni ده nickel؛ والـ Co ده cobalt، مش carbon + oxygen."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":42,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-chem.oxides-2","kind":"question","version":1,"ord":131,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.oxides","concepts":[{"concept_id":"chem.oxides","role":"primary"}],"title":"chem-s3-en.question-chem.oxides-2","payload":{"stem":"Nickel (II) oxide, NiO, is a basic oxide. What forms when it reacts with dilute sulphuric acid?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Nickel (II) sulphate and water","correct":true},{"id":"b","text":"Nickel (II) sulphate and hydrogen gas","correct":false},{"id":"c","text":"Nickel metal and water","correct":false},{"id":"d","text":"No reaction, because a metal oxide reacts only with water","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance (oxides: TiO2, V2O5, Cr2O3, ZnO pp.5-8)","difficulty":2,"concept_ids":["chem.oxides"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! Basic oxide + acid → salt + water."},"b":{"why":"Hydrogen gas comes from a metal with an acid. Here there is an oxide: its oxygen and the acid's hydrogen form water.","feedback":"Misconception: Metal oxides react with acids like metals, giving hydrogen."},"c":{"why":"An acid does not take oxygen away from an oxide to leave the metal. A basic oxide forms a salt with an acid.","feedback":"Misconception: The acid reduces the oxide to the metal."},"d":{"why":"A basic oxide behaves like a base, and a base reacts with an acid.","feedback":"Misconception: Metal oxides do not react with acids."}},"explanation":"A basic oxide + an acid → a salt + water (no gas). $\\ce{NiO + H2SO4 -> NiSO4 + H2O}$. The salt takes the metal from the oxide and the ending 'sulphate' from sulphuric acid. The O of the oxide and the H of the acid form water. Hydrogen gas forms when an active metal itself (not its oxide) reacts with a dilute acid."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! basic oxide + acid → salt + water."},"b":{"why":"الـ hydrogen gas بيطلع من metal مع acid، لكن هنا عندنا oxide. الـ oxygen بتاعه مع الـ hydrogen بتاع الـ acid بيكوّنوا water.","feedback":"الفكرة الغلط: إن الـ metal oxides بتتفاعل مع الـ acids زي الـ metals وتدي hydrogen."},"c":{"why":"الـ acid مش بياخد الـ oxygen من الـ oxide ويسيب الـ metal. الـ basic oxide مع الـ acid بيكوّن salt و water.","feedback":"الفكرة الغلط: إن الـ acid بيعمل reduce للـ oxide ويرجّعه metal."},"d":{"why":"الـ basic oxide بيتصرف زي الـ base، والـ base بيتفاعل مع الـ acid.","feedback":"الفكرة الغلط: إن الـ metal oxides مابتتفاعلش مع الـ acids."}},"explanation":"الـ basic oxide + الـ acid → salt + water (من غير gas). $\\ce{NiO + H2SO4 -> NiSO4 + H2O}$. الـ salt بياخد الـ metal من الـ oxide، وبياخد النهاية 'sulphate' من الـ sulphuric acid. والـ O بتاع الـ oxide مع الـ H بتاع الـ acid بيكوّنوا water. الـ hydrogen gas بيطلع لما يكون الـ metal نفسه (مش الـ oxide بتاعه) هو اللي بيتفاعل مع dilute acid."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":43,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.rusting-corrosion-1","kind":"question","version":1,"ord":132,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.rusting-corrosion","concepts":[{"concept_id":"chem.rusting-corrosion","role":"primary"}],"title":"chem-s3-en.question-chem.rusting-corrosion-1","payload":{"stem":"An iron anchor on a ship at sea rusts quickly. An iron statue in a very dry desert rusts very slowly. What is the best explanation?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"At sea, iron meets oxygen and moisture together; desert air has very little moisture.","correct":true},{"id":"b","text":"Desert air has no oxygen, so the statue cannot react with it.","correct":false},{"id":"c","text":"Water alone causes rusting, so oxygen plays no part.","correct":false},{"id":"d","text":"The desert heat protects iron from rusting.","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance pp.6-7 (resisting corrosion, galvanizing, plating) and the chromium oxide layer p.6","difficulty":2,"concept_ids":["chem.rusting-corrosion"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! Rusting needs oxygen and moisture together."},"b":{"why":"Air everywhere on Earth contains oxygen. Besides oxygen, iron also needs moisture to rust.","feedback":"Misconception: Desert air lacks oxygen."},"c":{"why":"Iron does not rust in boiled water with oil on top, where no air can reach it. Oxygen must be there too.","feedback":"Misconception: Water alone causes rust."},"d":{"why":"Heat speeds up most reactions rather than stopping them. What very dry air lacks is moisture.","feedback":"Misconception: Heat stops rusting."}},"explanation":"Rusting is the corrosion of iron. It needs oxygen and moisture (water) together. Sea air and sea spray give the anchor both. Desert air contains oxygen, but very little moisture, so the statue rusts very slowly."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ rusting محتاج oxygen و moisture مع بعض."},"b":{"why":"الهوا في أي مكان على الأرض فيه oxygen. والـ iron محتاج moisture كمان عشان يصدّي، وده اللي ناقص في الصحرا.","feedback":"الفكرة الغلط: إن هوا الصحرا مفيهوش oxygen."},"c":{"why":"الـ iron مابيصدّيش في ماية مغلية وعليها طبقة زيت، والهوا مش قادر يوصله. لازم يكون فيه oxygen كمان.","feedback":"الفكرة الغلط: إن الماية لوحدها بتعمل rust."},"d":{"why":"الحرارة بتسرّع أغلب التفاعلات، مش بتوقفها. اللي ناقص في الهوا الناشف جدًا هو الـ moisture.","feedback":"الفكرة الغلط: إن الحرارة بتوقّف الـ rusting."}},"explanation":"الـ rusting هو الـ corrosion بتاع الـ iron، ومحتاج oxygen و moisture (ماية) مع بعض. هوا البحر ورذاذه بيدّوا المرساة الاتنين. أما هوا الصحرا ففيه oxygen، لكن الـ moisture فيه قليلة جدًا، فالتمثال بيحصله rusting ببطء شديد."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":44,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-chem.rusting-corrosion-2","kind":"question","version":1,"ord":133,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.rusting-corrosion","concepts":[{"concept_id":"chem.rusting-corrosion","role":"primary"}],"title":"chem-s3-en.question-chem.rusting-corrosion-2","payload":{"stem":"An iron water tank on a roof is covered with a layer of red-brown rust. The owner says: \"Good, this rust layer now protects the tank, just like a coat of paint.\" Which reply is correct?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"No. Rust is porous and flakes off, so oxygen and moisture still reach the iron below.","correct":true},{"id":"b","text":"Yes. Rust is an oxide, and every oxide layer stops oxygen from reaching a metal.","correct":false},{"id":"c","text":"Yes. Rust is less reactive than iron, so the tank is now safe.","correct":false},{"id":"d","text":"No. But the only problem with rust is that it looks ugly.","correct":false}],"book_ref":"Prerequisite (preparatory science/chemistry); needed for Ch.1 economic importance pp.6-7 and the chromium oxide layer p.6 (contrast with porous rust)","difficulty":3,"concept_ids":["chem.rusting-corrosion"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! Rusting goes on under a porous layer."},"b":{"why":"Not every oxide layer seals the surface. Rust comes off when you rub it with a finger.","feedback":"Misconception: Any oxide layer protects a metal."},"c":{"why":"The rust itself may not react much, but the iron under it still rusts: air and water get through the rust.","feedback":"Misconception: A rusted surface is safe because rust is unreactive."},"d":{"why":"If rust were only ugly, an old rusty gate would stay strong for ever. In fact, the iron under the rust keeps being eaten away.","feedback":"Misconception: Rust is only a problem of appearance."}},"explanation":"Rust (hydrated iron (III) oxide) is porous and flakes off. Oxygen and moisture pass through it and reach fresh iron below, so rusting continues until the iron is eaten away. Paint is different: it is a continuous barrier that keeps air and moisture away. Keep this contrast for Chapter 1: the oxide layer on chromium is non-porous, so it does protect the metal."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ rusting بيكمّل تحت الطبقة الـ porous."},"b":{"why":"مش أي oxide layer بتقفل السطح. الـ rust بيتقشّر لما تحك فيه بصباعك، فالـ oxygen والـ moisture بيعدّوا منه.","feedback":"الفكرة الغلط: إن أي oxide layer بتحمي الـ metal."},"c":{"why":"ممكن الـ rust نفسه مايتفاعلش كتير، لكن الهوا والماية بيعدّوا منه ويوصلوا للـ iron اللي تحته، فالـ rusting بيكمّل.","feedback":"الفكرة الغلط: إن السطح اللي مصدّي يبقى أمان عشان الـ rust مش بيتفاعل."},"d":{"why":"الـ rust مش مجرد شكل وحش: الـ iron اللي تحته بيفضل يتآكل، وعشان كده البوابة القديمة المصدّية بتضعف.","feedback":"الفكرة الغلط: إن الـ rust مشكلته مجرد مشكلة شكل."}},"explanation":"الـ rust (hydrated iron (III) oxide) ده porous وبيتقشّر. الـ oxygen والـ moisture بيعدّوا منه ويوصلوا للـ iron الجديد اللي تحته، فالـ rusting بيكمّل لحد ما الـ iron يتآكل. الدهان حاجة تانية: ده حاجز متصل بيبعد الهوا والـ moisture. خلّي المقارنة دي في دماغك للفصل الأول: الـ oxide layer اللي على الـ chromium بتبقى non-porous، فهي فعلًا بتحمي الـ metal."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":45,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-redox.basic-1","kind":"question","version":1,"ord":134,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"redox.basic","concepts":[{"concept_id":"redox.basic","role":"primary"}],"title":"chem-s3-en.question-redox.basic-1","payload":{"stem":"Which of the following changes is a reduction?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"$Fe_2O_3 \\rightarrow Fe$","correct":true},{"id":"b","text":"$Fe \\rightarrow Fe_3O_4$","correct":false},{"id":"c","text":"$CO \\rightarrow CO_2$","correct":false},{"id":"d","text":"$H_2S \\rightarrow S$","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); needed for Ch.1 economic importance p.6 (oxidizing agents K2Cr2O7, MnO2)","difficulty":1,"concept_ids":["redox.basic"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Iron (III) oxide loses its oxygen."},"b":{"why":"Iron gains oxygen here, and gain of oxygen is oxidation, not reduction.","feedback":"Misconception: Gain of oxygen is reduction."},"c":{"why":"CO gains oxygen to become $CO_2$, and gain of oxygen is oxidation.","feedback":"Misconception: Any change of oxygen count is reduction."},"d":{"why":"Hydrogen is lost here, and loss of hydrogen is oxidation, not reduction.","feedback":"Misconception: Loss of hydrogen is reduction."}},"explanation":"Reduction = loss of oxygen (or gain of hydrogen). Oxidation = gain of oxygen (or loss of hydrogen). $Fe_2O_3 \\rightarrow Fe$: loses oxygen, so it is reduction. $Fe \\rightarrow Fe_3O_4$ and $CO \\rightarrow CO_2$: gain oxygen, so they are oxidation. $H_2S \\rightarrow S$: loses hydrogen, so it is oxidation."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ iron (III) oxide هنا بيخسر الـ oxygen بتاعه."},"b":{"why":"الـ iron هنا بيكسب oxygen، وكسب الـ oxygen ده oxidation، مش reduction.","feedback":"الفكرة الغلط: إن كسب الـ oxygen يبقى reduction."},"c":{"why":"الـ CO بيكسب oxygen ويبقى $CO_2$، وكسب الـ oxygen ده oxidation.","feedback":"الفكرة الغلط: إن أي تغيير في كمية الـ oxygen يبقى reduction."},"d":{"why":"هنا فيه hydrogen بيضيع، وخسارة الـ hydrogen دي oxidation، مش reduction.","feedback":"الفكرة الغلط: إن خسارة الـ hydrogen تبقى reduction."}},"explanation":"الـ reduction = خسارة oxygen (أو كسب hydrogen)، والـ oxidation = كسب oxygen (أو خسارة hydrogen). في $Fe_2O_3 \\rightarrow Fe$ المادة بتخسر oxygen، يبقى ده reduction. أما $Fe \\rightarrow Fe_3O_4$ و $CO \\rightarrow CO_2$ فبيكسبوا oxygen، يبقى دول oxidation. وفي $H_2S \\rightarrow S$ بيخسر hydrogen، يبقى ده oxidation."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":46,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"},{"relation":"beyond"}]},{"id":"chem-s3-en.question-redox.basic-2","kind":"question","version":1,"ord":135,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"redox.basic","concepts":[{"concept_id":"redox.basic","role":"primary"}],"title":"chem-s3-en.question-redox.basic-2","payload":{"stem":"Burning magnesium keeps burning in carbon dioxide gas: $\\ce{2Mg + CO2 -> 2MgO + C}$. Which substance is the oxidizing agent?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$CO_2$","correct":true},{"id":"b","text":"Mg","correct":false},{"id":"c","text":"MgO","correct":false},{"id":"d","text":"C","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); needed for Ch.1 economic importance p.6 (oxidizing agents K2Cr2O7, MnO2)","difficulty":2,"concept_ids":["redox.basic"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! $CO_2$ gives its oxygen to magnesium and is itself reduced."},"b":{"why":"Mg gains oxygen, so Mg is oxidized: it is the reducing agent. The oxidizing agent is the substance that supplies the oxygen.","feedback":"Misconception: The substance that is oxidized is the oxidizing agent."},"c":{"why":"MgO is a product, and the agents are among the reactants.","feedback":"Misconception: A product can be the oxidizing agent."},"d":{"why":"Carbon is a product, and the agents are among the reactants. C forms from the reactant that lost oxygen.","feedback":"Misconception: The element left free is the oxidizing agent."}},"explanation":"Mg gains oxygen (Mg → MgO): Mg is oxidized, so Mg is the reducing agent. $CO_2$ loses oxygen ($CO_2$ → C): $CO_2$ is reduced. The substance that supplies oxygen to another substance is the oxidizing agent, so $CO_2$ is the oxidizing agent. Remember: the oxidizing agent is itself reduced. Chapter 1 calls $K_2Cr_2O_7$ and $MnO_2$ oxidizing agents for the same reason."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ $CO_2$ بيدّي الـ oxygen بتاعه للـ magnesium، وهو نفسه بيبقى reduced."},"b":{"why":"الـ Mg بيكسب oxygen، يعني الـ Mg هو اللي oxidized: هو الـ reducing agent. الـ oxidizing agent هو المادة اللي بتدّي الـ oxygen.","feedback":"الفكرة الغلط: إن المادة اللي بتبقى oxidized هي الـ oxidizing agent."},"c":{"why":"الـ MgO ده product، والـ agents بيبقوا من ضمن الـ reactants.","feedback":"الفكرة الغلط: إن الـ product ممكن يبقى هو الـ oxidizing agent."},"d":{"why":"الـ carbon ده product، والـ agents بيبقوا من ضمن الـ reactants. الـ C بيطلع من الـ reactant اللي خسر oxygen.","feedback":"الفكرة الغلط: إن العنصر اللي بيطلع حر في الآخر هو الـ oxidizing agent."}},"explanation":"الـ Mg بيكسب oxygen (Mg → MgO): يعني الـ Mg هو اللي oxidized، فهو الـ reducing agent. والـ $CO_2$ بيخسر oxygen ($CO_2$ → C): يعني الـ $CO_2$ هو اللي reduced. والمادة اللي بتدّي oxygen لمادة تانية اسمها الـ oxidizing agent، عشان كده الـ $CO_2$ هو الـ oxidizing agent. افتكر: الـ oxidizing agent نفسه بيبقى reduced. وعشان نفس السبب ده، الفصل الأول بيسمّي الـ $K_2Cr_2O_7$ والـ $MnO_2$ oxidizing agents."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":47,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.activity-series-1","kind":"question","version":1,"ord":136,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.activity-series","concepts":[{"concept_id":"chem.activity-series","role":"primary"}],"title":"chem-s3-en.question-chem.activity-series-1","payload":{"stem":"Which of the following metals does NOT displace hydrogen from dilute hydrochloric acid?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"Copper","correct":true},{"id":"b","text":"Zinc","correct":false},{"id":"c","text":"Iron","correct":false},{"id":"d","text":"Magnesium","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); needed for Ch.1 'variation in activity' (copper limited activity, scandium highly active) p.13","difficulty":1,"concept_ids":["chem.activity-series"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! Copper lies below hydrogen in the activity series."},"b":{"why":"Zinc is a transition-series metal too, but it is above hydrogen in the activity series.","feedback":"Misconception: Metals of the transition series never react with dilute acids."},"c":{"why":"Iron is hard, but hardness is not activity. Iron is above hydrogen in the series.","feedback":"Misconception: A hard metal is an unreactive metal."},"d":{"why":"Magnesium is above hydrogen in the series, so it displaces hydrogen from dilute acid.","feedback":"Misconception: Light metals do not react with acids."}},"explanation":"In the activity series (K, Na, Ca, Mg, Al, Zn, Fe, Sn, Pb, (H), Cu, Hg, Ag, Pt, Au), metals above hydrogen displace it from dilute acids, and metals below hydrogen do not. Copper is below hydrogen, so it gives no hydrogen with dilute HCl. This matches Chapter 1: copper has limited chemical activity, while scandium is highly active."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ copper مكانه تحت الـ hydrogen في الـ activity series."},"b":{"why":"الـ zinc هو كمان metal من الـ transition series، لكنه فوق الـ hydrogen في الـ activity series، فبيطلّع hydrogen من الـ acid.","feedback":"الفكرة الغلط: إن metals الـ transition series أبدًا ما بتتفاعلش مع الـ dilute acids."},"c":{"why":"الـ iron صلب، لكن الصلابة حاجة والـ activity حاجة تانية. والـ iron فوق الـ hydrogen في الـ series، فبيطلّع hydrogen.","feedback":"الفكرة الغلط: إن الـ metal الصلب يبقى metal مش بيتفاعل."},"d":{"why":"شريط الـ magnesium بيفوّر في الـ acid، لأن الـ magnesium فوق الـ hydrogen في الـ series.","feedback":"الفكرة الغلط: إن الـ metals الخفيفة مش بتتفاعل مع الـ acids."}},"explanation":"في الـ activity series (K, Na, Ca, Mg, Al, Zn, Fe, Sn, Pb, (H), Cu, Hg, Ag, Pt, Au)، الـ metals اللي فوق الـ hydrogen بتعمل displace ليه من الـ dilute acids، واللي تحت الـ hydrogen مش بتعمل كده. الـ copper تحت الـ hydrogen، عشان كده مش بيطلّع hydrogen مع الـ dilute HCl. وده نفس اللي في الفصل الأول: الـ copper الـ chemical activity بتاعته محدودة، إنما الـ scandium highly active."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":48,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.activity-series-2","kind":"question","version":1,"ord":137,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"chem.activity-series","concepts":[{"concept_id":"chem.activity-series","role":"primary"}],"title":"chem-s3-en.question-chem.activity-series-2","payload":{"stem":"Part of the activity series (most active first): Mg > Zn > Fe > (H) > Cu > Ag.\nA strip of zinc is put in copper (II) sulphate solution. What happens?","tags":["diagnostic","prerequisite","data"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Zinc displaces copper: copper metal forms on the strip and zinc sulphate forms in solution.","correct":true},{"id":"b","text":"No reaction, because a metal does not react with a salt solution.","correct":false},{"id":"c","text":"Copper displaces zinc from the strip, and the strip dissolves.","correct":false},{"id":"d","text":"Hydrogen gas is given off, because zinc is above hydrogen.","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); needed for Ch.1 'variation in activity' (copper limited activity, scandium highly active) p.13","difficulty":2,"concept_ids":["chem.activity-series"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! The more active metal displaces the less active one."},"b":{"why":"Metals can react with salt solutions. Zn is above Cu in the series, so zinc is the more active one.","feedback":"Misconception: Metals never react with salt solutions."},"c":{"why":"Copper is in the solution and zinc is the solid. A less active metal cannot push out a more active one.","feedback":"Misconception: The metal in the solution displaces the solid metal."},"d":{"why":"Zinc gives hydrogen with an acid, but copper (II) sulphate solution is not an acid. Here zinc meets copper ions instead.","feedback":"Misconception: Any metal above hydrogen gives hydrogen in any solution."}},"explanation":"A more active metal displaces a less active metal from the solution of its salt. Zn is above Cu in the series, so zinc displaces copper: $\\ce{Zn + CuSO4 -> ZnSO4 + Cu}$. Red-brown copper metal coats the zinc strip. Copper cannot displace zinc, because copper is less active. No hydrogen forms, because there is no acid."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ metal الأكتر active بيعمل displace للـ metal الأقل active."},"b":{"why":"الـ metals ممكن تتفاعل مع الـ salt solutions. والـ Zn فوق الـ Cu في الـ series، يعني الـ Zn هو الأكتر active.","feedback":"الفكرة الغلط: إن الـ metals أبدًا ما بتتفاعلش مع الـ salt solutions."},"c":{"why":"الـ copper هو اللي في الـ solution، والـ zinc هو الصلب. والـ metal الأقل active مايقدرش يطرد metal أكتر active.","feedback":"الفكرة الغلط: إن الـ metal اللي في الـ solution هو اللي بيعمل displace للـ metal الصلب."},"d":{"why":"الـ zinc بيطلّع hydrogen مع الـ acid، لكن الـ copper (II) sulphate solution مش acid. الـ zinc هنا بيقابل salt solution.","feedback":"الفكرة الغلط: إن أي metal فوق الـ hydrogen بيطلّع hydrogen في أي solution."}},"explanation":"الـ metal الأكتر active بيعمل displace للـ metal الأقل active من الـ solution بتاع الـ salt بتاعه. الـ Zn فوق الـ Cu في الـ series، فالـ zinc بيعمل displace للـ copper: $\\ce{Zn + CuSO4 -> ZnSO4 + Cu}$. وبيترسب copper metal لونه أحمر بني ويغطي شريط الـ zinc. والـ copper ميقدرش يعمل displace للـ zinc، عشان الـ copper أقل active. ومفيش hydrogen بيطلع، عشان مفيش acid."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":49,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":83,"page_to":83,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"chem-s3-en.question-atom.isotopes-1","kind":"question","version":1,"ord":138,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"atom.isotopes","concepts":[{"concept_id":"atom.isotopes","role":"primary"}],"title":"chem-s3-en.question-atom.isotopes-1","payload":{"stem":"Cobalt-59 and cobalt-60 are two isotopes of cobalt ($_{27}$Co). How are their atoms different?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"A cobalt-60 atom has one more neutron.","correct":true},{"id":"b","text":"A cobalt-60 atom has one more proton.","correct":false},{"id":"c","text":"A cobalt-60 atom has one more electron.","correct":false},{"id":"d","text":"Cobalt-60 has a different atomic number, 28.","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); needed for Ch.1 cobalt-60 (p.7) and the atomic mass note on nickel isotopes (p.12)","difficulty":1,"concept_ids":["atom.isotopes"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Same protons, different neutrons."},"b":{"why":"The atomic number 27 fixes the number of protons. With a different number of protons, the atom would no longer be cobalt.","feedback":"Misconception: Isotopes differ in their number of protons."},"c":{"why":"Both neutral atoms have the same atomic number, so each one has the same number of electrons: 27.","feedback":"Misconception: Isotopes differ in their number of electrons."},"d":{"why":"An atom with atomic number 28 is a different element, so it could not be cobalt.","feedback":"Misconception: The number in an isotope's name changes the atomic number."}},"explanation":"Isotopes are atoms of the same element: the same atomic number (the same number of protons, here 27) but different mass numbers. Mass number = protons + neutrons. Cobalt-59: 59 − 27 = 32 neutrons. Cobalt-60: 60 − 27 = 33 neutrons. So a cobalt-60 atom has one more neutron. Each neutral atom still has 27 electrons."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! نفس الـ protons، و neutrons مختلفة."},"b":{"why":"لو عدد الـ protons اتغيّر، الذرة مش هتفضل cobalt. الـ atomic number 27 بيثبّت عدد الـ protons.","feedback":"الفكرة الغلط: إن الـ isotopes بتختلف في عدد الـ protons."},"c":{"why":"الذرتين المتعادلتين ليهم نفس الـ atomic number، فكل واحدة فيهم فيها 27 electrons.","feedback":"الفكرة الغلط: إن الـ isotopes بتختلف في عدد الـ electrons."},"d":{"why":"الـ atomic number 28 ده بتاع عنصر تاني، مش الـ cobalt. الـ isotopes ليها نفس الـ atomic number.","feedback":"الفكرة الغلط: إن الرقم اللي في اسم الـ isotope بيغيّر الـ atomic number."}},"explanation":"الـ isotopes هي ذرات من نفس العنصر: نفس الـ atomic number (يعني نفس عدد الـ protons، وهنا 27)، لكن الـ mass numbers مختلفة. والـ mass number = protons + neutrons. الـ cobalt-59: 59 − 27 = 32 neutrons. والـ cobalt-60: 60 − 27 = 33 neutrons. يبقى ذرة الـ cobalt-60 فيها neutron زيادة واحد. وكل ذرة متعادلة فيهم لسه فيها 27 electrons."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":50,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-atom.isotopes-2","kind":"question","version":1,"ord":139,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"atom.isotopes","concepts":[{"concept_id":"atom.isotopes","role":"primary"}],"title":"chem-s3-en.question-atom.isotopes-2","payload":{"stem":"Copper has two stable isotopes: copper-63 (abundance 69%) and copper-65 (abundance 31%). Take the mass of each isotope as equal to its mass number. Calculate the average atomic mass of copper, to one decimal place.","tags":["diagnostic","prerequisite","calculation","data"],"type":"numeric","bloom":"apply","answer":{"unit":"u","value":63.6,"tolerance":0.05},"book_ref":"Prerequisite (preparatory chemistry); needed for Ch.1 cobalt-60 (p.7) and the atomic mass note on nickel isotopes (p.12)","difficulty":3,"concept_ids":["atom.isotopes"],"est_seconds":90},"layer":{"explanation":"Average atomic mass = the sum of (mass × abundance) for each isotope. (63 × 69 + 65 × 31) / 100 = (4347 + 2015) / 100 = 6362 / 100 = 63.62 ≈ 63.6 u. Check: the answer lies between 63 and 65, and closer to 63, because copper-63 is the more abundant isotope. Common mistake: taking the simple mean, (63 + 65) / 2 = 64, which ignores the abundances. The book's table gives copper's atomic mass as 63.5, because the real isotope masses and abundances differ slightly from the round values used here."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ average atomic mass = مجموع (الكتلة × الـ abundance) لكل isotope. (63 × 69 + 65 × 31) / 100 = (4347 + 2015) / 100 = 6362 / 100 = 63.62 ≈ 63.6 u. تشييك: الناتج لازم يطلع بين 63 و 65، وأقرب لـ 63، عشان الـ copper-63 هو الـ isotope اللي الـ abundance بتاعته أكبر. أشهر غلطة: إنك تاخد المتوسط العادي، (63 + 65) / 2 = 64، وده بيتجاهل الـ abundances. والجدول اللي في الكتاب بيدّي الـ atomic mass بتاعة الـ copper 63.5، عشان الكتل الحقيقية للـ isotopes ونسب الـ abundance بتختلف شوية عن الأرقام المقرّبة اللي استخدمناها هنا."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":51,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.radioactivity-gamma-1","kind":"question","version":1,"ord":140,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"phys.radioactivity-gamma","concepts":[{"concept_id":"phys.radioactivity-gamma","role":"primary"}],"title":"chem-s3-en.question-phys.radioactivity-gamma-1","payload":{"stem":"Which statement describes gamma rays?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"High-energy electromagnetic rays with high penetrating power","correct":true},{"id":"b","text":"Positively charged particles that a sheet of paper can stop","correct":false},{"id":"c","text":"Low-energy rays, weaker than visible light","correct":false},{"id":"d","text":"Rays that make every object they hit radioactive","correct":false,"misconception_id":"phys.radioactivity-gamma.mc1"}],"book_ref":"Prerequisite (preparatory science); needed for Ch.1 7-Cobalt: cobalt-60 gamma rays, p.7","difficulty":1,"concept_ids":["phys.radioactivity-gamma"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Correct! They belong to the same family as light, at the high-energy end."},"b":{"why":"That describes charged particles, not rays. Gamma rays have no charge; they are rays in the same family as light.","feedback":"Misconception: Gamma rays are charged particles."},"c":{"why":"Gamma rays are at the high-energy end of the electromagnetic family, with more energy than visible light.","feedback":"Misconception: Invisible rays are weak rays."},"d":{"why":"Rays from a source pass through an object and add no radioactive substance to it, so it does not become radioactive.","feedback":"Misconception: Anything exposed to gamma rays becomes radioactive."}},"explanation":"Some isotopes have unstable nuclei that decay and give out radiation. Gamma rays are electromagnetic rays, like light but with a much shorter wavelength. They have very high energy, no charge and high penetrating power. An object exposed to gamma rays does not become radioactive: the rays pass through it, and no radioactive substance is added to it."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! دي من نفس عيلة الضوء، عند الطرف اللي طاقته عالية."},"b":{"why":"ده وصف charged particles، مش أشعة. الـ gamma rays مالهاش charge؛ دي أشعة من نفس عيلة الضوء.","feedback":"الفكرة الغلط: إن الـ gamma rays دي charged particles."},"c":{"why":"الـ gamma rays واقفة عند طرف الطاقة العالية في عيلة الأشعة الـ electromagnetic، وطاقتها أكتر من الـ visible light.","feedback":"الفكرة الغلط: إن الأشعة اللي مش بنشوفها تبقى أشعة ضعيفة."},"d":{"why":"الأشعة اللي طالعة من المصدر بتعدّي من الجسم ومابتزوّدش جواه أي مادة radioactive، فالجسم مابيبقاش radioactive.","feedback":"الفكرة الغلط: إن أي حاجة بتتعرض للـ gamma rays بتبقى radioactive."}},"explanation":"فيه isotopes الـ nuclei بتاعتها unstable، فبتعمل decay وبتطلّع radiation. الـ gamma rays دي electromagnetic rays، زي الضوء لكن الـ wavelength بتاعها أقصر بكتير. طاقتها عالية جدًا، ومالهاش charge، وليها high penetrating power. والجسم اللي بيتعرض للـ gamma rays مش بيبقى radioactive: الأشعة بتعدّي منه، ومش بتتضاف له أي مادة radioactive."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":52,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.radioactivity-gamma-2","kind":"question","version":2,"ord":141,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"phys.radioactivity-gamma","concepts":[{"concept_id":"phys.radioactivity-gamma","role":"primary"}],"title":"chem-s3-en.question-phys.radioactivity-gamma-2","payload":{"stem":"A beam of gamma rays is aimed at three materials, one at a time: a sheet of paper, an aluminum sheet 5 mm thick, and a thick block of lead. Which result is expected?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"The rays pass through the paper and the aluminum; the thick lead block greatly reduces them.","correct":true},{"id":"b","text":"The sheet of paper stops the rays.","correct":false},{"id":"c","text":"The aluminum sheet stops the rays completely.","correct":false},{"id":"d","text":"The rays pass through all three materials equally.","correct":false}],"book_ref":"Prerequisite (preparatory science); needed for Ch.1 7-Cobalt: cobalt-60 gamma rays, p.7","difficulty":2,"concept_ids":["phys.radioactivity-gamma"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! Only thick, dense materials reduce gamma rays strongly."},"b":{"why":"Paper stops weakly penetrating radiation, but gamma rays have high penetrating power and pass through it.","feedback":"Misconception: Gamma rays are as weak as charged particles."},"c":{"why":"A few millimetres of metal stop weaker radiation, but not the most penetrating rays: gamma rays pass through it.","feedback":"Misconception: Any metal sheet stops gamma rays."},"d":{"why":"A thick, dense block absorbs far more than a thin sheet of paper, so the lead reduces the rays strongly.","feedback":"Misconception: High penetrating power means nothing can reduce the rays."}},"explanation":"Gamma rays have high penetrating power: they pass easily through paper and through a few millimetres of aluminum. Only thick, dense materials, such as lead or thick concrete, reduce them strongly. This is why cobalt-60 gamma rays can check thick industrial products and welding connections for hidden cracks (Ch.1 p.7)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! المواد التخينة والكثيفة هي اللي بتقلل الـ gamma rays بقوة."},"b":{"why":"الورقة بتوقف الـ radiation اللي اختراقها ضعيف، لكن الـ gamma rays الـ penetrating power بتاعها عالي فبتعدّي منها.","feedback":"الفكرة الغلط: إن الـ gamma rays ضعيفة زي الـ charged particles."},"c":{"why":"كام ملّي من الـ metal بيوقفوا radiation أضعف، لكن مش الأشعة اللي اختراقها هو الأعلى: الـ gamma rays بتعدّي منهم.","feedback":"الفكرة الغلط: إن أي لوح metal بيوقف الـ gamma rays."},"d":{"why":"البلوك التخين الكثيف بيمتص أكتر بكتير من ورقة رفيعة، فالـ lead بيقلّل الأشعة جامد.","feedback":"الفكرة الغلط: إن الـ high penetrating power معناها إن مفيش حاجة تقدر تقلل الأشعة."}},"explanation":"الـ gamma rays ليها high penetrating power: بتعدّي بسهولة من الورق ومن كام ملّي من الـ aluminum. المواد التخينة والكثيفة، زي الـ lead أو الخرسانة التخينة، هي اللي بتقللها بقوة. وعشان كده الـ gamma rays بتاعة الـ cobalt-60 بتنفع في فحص المنتجات الصناعية التخينة ووصلات اللحام، عشان نكشف الشروخ المستخبية جواها (الفصل 1، ص 7)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":53,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"beyond"}]},{"id":"chem-s3-en.question-te.uses-sc-ti-1","kind":"question","version":2,"ord":142,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-sc-ti","concepts":[{"concept_id":"te.uses-sc-ti","role":"primary"}],"title":"chem-s3-en.question-te.uses-sc-ti-1","payload":{"stem":"Choose the correct answer: A little scandium is added to aluminum in the manufacture of MiG fighter jets, because the alloy formed is ...","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"light and very hard","correct":true},{"id":"b","text":"heavy and as dense as steel","correct":false},{"id":"c","text":"inert, so the body does not reject it","correct":false},{"id":"d","text":"able to give light that looks like sunlight","correct":false}],"book_ref":"Ch.1 economic importance: 1-Scandium, 2-Titanium, p.5 (fig 1-2)","difficulty":2,"concept_ids":["te.uses-sc-ti"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Aluminum is light, and a little scandium makes the alloy very hard."},"b":{"why":"A fighter jet must be light to fly fast, so the book would not choose a heavy alloy.","feedback":"Misconception: Making an alloy hard makes it dense like steel."},"c":{"why":"That is the reason for a medical use of another element, titanium; the body of a jet needs lightness and great hardness from an alloy.","feedback":"Misconception: Mixing up the Sc-Al alloy with titanium's medical use."},"d":{"why":"That is scandium's other use, in lamps; the body of a jet needs lightness and great hardness.","feedback":"Misconception: Mixing up scandium's two uses (alloy and mercury vapour lamps)."}},"explanation":"Book (p.5): adding a little amount of scandium to aluminum gives a light and very hard alloy, used in the manufacture of MiG fighter jets. Aluminum gives lightness; a little scandium makes it very hard. Note: only a little scandium is added; the jet is not made of pure scandium. Scandium's second use: it is added to mercury vapour lamps to produce high-quality light that looks like sunlight, so it is used in TV photography at night. 'Inert, not rejected by the body' is the reason for titanium in dental implants."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ aluminum خفيف، وكمية صغيرة من الـ scandium بتخلّي الـ alloy صلب جدًا."},"b":{"why":"الطيارة الحربية لازم تبقى خفيفة عشان تطير بسرعة، فالكتاب مش هيختار alloy تقيل.","feedback":"الفكرة الغلط: إن الـ alloy لما يبقى صلب، كثافته بتبقى عالية زي الـ steel."},"c":{"why":"ده سبب استخدام طبي لعنصر تاني، الـ titanium. جسم الطيارة الحربية محتاج خفة وصلابة، مش إن الجسم مايرفضوش.","feedback":"الفكرة الغلط: خلط الـ Sc-Al alloy بالاستخدام الطبي بتاع الـ titanium."},"d":{"why":"ده الاستخدام التاني للـ scandium، في اللمبات، وده مالوش علاقة بجسم الطيارة اللي محتاج خفة وصلابة.","feedback":"الفكرة الغلط: خلط استخدامين الـ scandium ببعض (الـ alloy والـ mercury vapour lamps)."}},"explanation":"الكتاب (ص 5): لما نضيف كمية صغيرة من الـ scandium للـ aluminum بيطلع alloy خفيف وصلب جدًا، بيستخدموه في صناعة طيارات الـ MiG الحربية. الـ aluminum بيدّي الخفة، والكمية الصغيرة من الـ scandium بتخلّيه صلب جدًا. خلّي بالك: اللي بيتضاف من الـ scandium كمية صغيرة بس، والطيارة مش معمولة من scandium نقي. الاستخدام التاني للـ scandium: بيتضاف للـ mercury vapour lamps عشان تدّي ضوء عالي الجودة شبه ضوء الشمس، وعشان كده بيستخدموه في التصوير التلفزيوني بالليل. أما «inert والجسم مابيرفضوش» فده سبب استخدام الـ titanium في زراعة الأسنان."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":54,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-v-cr-1","kind":"question","version":1,"ord":143,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-v-cr","concepts":[{"concept_id":"te.uses-v-cr","role":"primary"}],"title":"chem-s3-en.question-te.uses-v-cr-1","payload":{"stem":"Choose the correct answer: Vanadium pentoxide ($V_2O_5$) is used ...","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"as a catalyst and as a dye in the ceramics and glass industry","correct":true},{"id":"b","text":"as a strong oxidizing agent in the dry cell","correct":false},{"id":"c","text":"in sun protection cosmetics to prevent the effect of UV","correct":false},{"id":"d","text":"in the manufacture of car springs","correct":false}],"book_ref":"Ch.1 economic importance: 3-Vanadium, 4-Chromium, p.6","difficulty":2,"concept_ids":["te.uses-v-cr"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! $V_2O_5$ has both uses."},"b":{"why":"That is the use of a manganese compound; the book links vanadium's oxide to the ceramics and glass industry.","feedback":"Misconception: Mixing up $V_2O_5$ with $MnO_2$."},"c":{"why":"That use belongs to the oxide of titanium; the book gives vanadium's oxide dye and catalyst uses.","feedback":"Misconception: Mixing up $V_2O_5$ with $TiO_2$."},"d":{"why":"Car springs use vanadium metal added to steel, not this oxide; the oxide itself has dye and catalyst uses.","feedback":"Misconception: Mixing up the use of the compound with the use of the alloy."}},"explanation":"Book (p.6): vanadium pentoxide is used as dyes in the manufacture of ceramics and in the glass industry, as a catalyst, and in the manufacture of strong magnetic conductors. (Its best-known catalytic use is in the preparation of sulphuric acid by the contact method, p.15.) Vanadium metal is different: a small portion added to steel gives an alloy of high hardness that resists corrosion, used in car springs. $MnO_2$ is the oxidizing agent in the dry cell; $TiO_2$ is used in sunscreen."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ $V_2O_5$ ليه الاستخدامين دول."},"b":{"why":"ده استخدام compound بتاع الـ manganese. الكتاب بيربط الـ oxide بتاع الـ vanadium بصناعة الـ ceramics والـ glass.","feedback":"الفكرة الغلط: إنك تخلط بين الـ $V_2O_5$ والـ $MnO_2$."},"c":{"why":"الاستخدام ده بتاع الـ oxide بتاع الـ titanium، مش الـ oxide بتاع الـ vanadium.","feedback":"الفكرة الغلط: إنك تخلط بين الـ $V_2O_5$ والـ $TiO_2$."},"d":{"why":"الـ car springs بتستخدم الـ vanadium الـ metal اللي بيتضاف للـ steel، مش الـ oxide ده.","feedback":"الفكرة الغلط: إنك تخلط بين استخدام الـ compound واستخدام الـ alloy."}},"explanation":"الكتاب (p.6): الـ vanadium pentoxide بيتستخدم كـ dyes في صناعة الـ ceramics وفي صناعة الـ glass، وكـ catalyst، وفي صناعة الـ strong magnetic conductors. (وأشهر استخدام ليه كـ catalyst هو تحضير الـ sulphuric acid بالـ contact method، p.15.) الـ vanadium الـ metal حاجة تانية: كمية صغيرة منه بتتضاف للـ steel بتدي alloy ليه high hardness وبيقاوم الـ corrosion، وده اللي بيتعمل منه الـ car springs. والـ $MnO_2$ هو الـ oxidizing agent في الـ dry cell؛ والـ $TiO_2$ بيتستخدم في الـ sunscreen."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":55,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.chromium-oxide-layer-1","kind":"question","version":1,"ord":144,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.chromium-oxide-layer","concepts":[{"concept_id":"te.chromium-oxide-layer","role":"primary"}],"title":"chem-s3-en.question-te.chromium-oxide-layer-1","payload":{"stem":"Give reasons: A chromium-plated tap stays shiny for years in the moist air of a bathroom, although chromium is a chemically active metal.","tags":["exam-style","give-reasons","new-case"],"type":"short","bloom":"understand","answer":"Key points: (1) Chromium is chemically active, so it reacts with the oxygen of air and an oxide forms on its surface. (2) The molecular volume of the produced oxide is larger than that of the metal atoms it formed from. (3) So the oxide forms a continuous, non-porous layer over the surface. (4) This layer prevents the continued interaction of the metal with the oxygen of air, so chromium resists the effect of the atmosphere and the tap stays shiny.","book_ref":"Ch.1 economic importance: 4-Chromium, p.6; form of Evaluation Q7 (give reasons), p.27","difficulty":3,"concept_ids":["te.chromium-oxide-layer"],"est_seconds":120},"layer":{"explanation":"Model answer: Chromium is a chemically active metal, so it does react with the oxygen of air. But the oxide formed on its surface has a molecular volume larger than that of the metal atoms it came from. The oxide therefore covers the whole surface as a non-porous layer. This layer prevents the continued interaction of chromium with the oxygen of air, so the metal under it is protected and stays shiny (book p.6). Words your exam answer must contain: active metal, oxide layer, molecular volume larger than the metal atoms, non-porous, prevents continued interaction with oxygen. Common mistakes: (1) 'chromium is an inactive metal' (the book says it is active); (2) 'any oxide layer protects' (rust on iron is porous and flakes off, so iron keeps rusting)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الإجابة النموذجية: الـ chromium ده active metal كيميائيًا، فهو فعلًا بيتفاعل مع الـ oxygen اللي في الهوا. لكن الـ oxide اللي بيتكوّن على سطحه الـ molecular volume بتاعه أكبر من الـ molecular volume بتاع ذرات الـ metal اللي جه منها. وعشان كده الـ oxide بيغطّي السطح كله كطبقة non-porous. الطبقة دي بتمنع إن الـ chromium يكمّل تفاعل مع الـ oxygen اللي في الهوا، فالـ metal اللي تحتها بيفضل محمي ولامع (الكتاب ص 6). الكلمات اللي لازم تبقى في إجابتك في الامتحان: active metal، oxide layer، molecular volume larger than the metal atoms، non-porous، prevents continued interaction with oxygen. غلطات بتتكرر: (1) إنك تقول إن الـ chromium ده inactive metal (الكتاب بيقول إنه active)؛ (2) إنك تقول إن أي oxide layer بتحمي (الـ rust على الـ iron طبقته porous وبتتقشّر، فالـ iron بيفضل يصدّي)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":56,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-mn-1","kind":"question","version":1,"ord":145,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-mn","concepts":[{"concept_id":"te.uses-mn","role":"primary"}],"title":"chem-s3-en.question-te.uses-mn-1","payload":{"stem":"The table describes three materials P, Q and R that contain manganese. Which choice gives the material for a railway track and the material for soft-drink cans?","tags":["exam-style","choose","data","new-case"],"type":"mcq","bloom":"apply","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["P","brittle; breaks when hammered"],["Q","harder than steel"],["R","resists corrosion"]],"caption":"Three manganese materials (descriptions from the book's reasons)","headers":["Material","Property"]},"children":[]}}},"choices":[{"id":"a","text":"Track: Q; cans: R","correct":true},{"id":"b","text":"Track: P; cans: R","correct":false},{"id":"c","text":"Track: R; cans: Q","correct":false},{"id":"d","text":"Track: Q; cans: Q","correct":false}],"book_ref":"Ch.1 economic importance: 5-Manganese, p.6","difficulty":3,"concept_ids":["te.uses-mn"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Correct! The track needs great hardness; the cans must resist corrosion."},"b":{"why":"P breaks when hammered, so it would break under the weight of heavy trains.","feedback":"Misconception: Pure manganese can be used as a metal."},"c":{"why":"A railway track needs great hardness under the weight of heavy trains, and that is Q's property, not R's.","feedback":"Misconception: Swapping the reasons of the two alloys."},"d":{"why":"Q is very hard, but a drink can needs most to resist corrosion from the drink it holds for months, and that is R's property.","feedback":"Misconception: The hardest material is the best choice for every use."}},"explanation":"P is brittle, like pure manganese. So manganese is not used as a pure metal; it is always used as alloys or compounds (book p.6). Q matches ferromanganese alloy. It is used in railway track, because it is harder than steel. R matches aluminum and manganese alloys. They are used in the manufacture of soft-drink cans, because they resist corrosion. So: track Q, cans R. Each use is chosen by a property: hardness for track, resisting corrosion for cans."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! القضبان محتاجة صلادة عالية، والعلب لازم تقاوم الـ corrosion."},"b":{"why":"الـ P هش وبيتكسر لما يتطرق، فهيتكسر تحت وزن القطارات التقيلة.","feedback":"الفكرة الغلط: إن الـ manganese النقي ممكن يُستخدم كـ metal."},"c":{"why":"القضبان محتاجة صلادة عالية عشان تستحمل وزن القطارات التقيلة، والـ R خاصيته مقاومة الـ corrosion، مش الصلادة.","feedback":"الفكرة الغلط: إنك تبدّل سبب الـ alloy ده بسبب التاني."},"d":{"why":"الـ Q صلد جدًا، لكن الصلادة مش أهم حاجة علبة المشروب محتاجاها: العلبة اللي شايلة مشروب لشهور محتاجة تقاوم الـ corrosion.","feedback":"الفكرة الغلط: إن أصلد مادة هي أحسن اختيار لأي استخدام."}},"explanation":"الـ P هش (brittle)، زي الـ manganese النقي. وعشان كده الـ manganese مش بيُستخدم كـ metal نقي؛ دايمًا بيُستخدم في alloys أو compounds (الكتاب ص 6). الـ Q بيطابق الـ ferromanganese alloy، وده بيُستخدم في قضبان السكة الحديد لأنه أصلد من الـ steel. والـ R بيطابق الـ alloys بتاعة الـ aluminum والـ manganese، ودي بتُستخدم في صناعة علب المياه الغازية لأنها بتقاوم الـ corrosion. يعني: القضبان Q، والعلب R. وكل استخدام بيتختار على حسب خاصية: الصلادة للقضبان، ومقاومة الـ corrosion للعلب."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":57,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-fe-co-1","kind":"question","version":2,"ord":146,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-fe-co","concepts":[{"concept_id":"te.uses-fe-co","role":"primary"},{"concept_id":"chem.catalyst","role":"secondary"}],"title":"chem-s3-en.question-te.uses-fe-co-1","payload":{"stem":"Choose the correct answer: Iron is used as a catalyst in the Fischer-Tropsch method. Its role there is to ...","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"speed up the change of water gas into fuel, without being used up","correct":true},{"id":"b","text":"react with water vapour and turn it into fuel","correct":false,"misconception_id":"te.uses-fe-co.mc1"},{"id":"c","text":"be used up, so fresh iron is added for each batch","correct":false,"misconception_id":"chem.catalyst.mc1"},{"id":"d","text":"supply hydrogen that combines with carbon monoxide","correct":false}],"book_ref":"Ch.1 economic importance: 6-Iron, 7-Cobalt (printed '27-Cobalt'), pp.6-7","difficulty":3,"concept_ids":["te.uses-fe-co","chem.catalyst"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! A catalyst speeds up the reaction and is not consumed."},"b":{"why":"Water gas is not water vapour: it is a mixture of two gases, hydrogen and carbon monoxide.","feedback":"Misconception: Water gas is water vapour."},"c":{"why":"A catalyst does not run out during a reaction: its mass at the end is the same as at the start, so no fresh iron is needed.","feedback":"Misconception: The catalyst is consumed in the reaction."},"d":{"why":"Iron has no hydrogen to give: the hydrogen in this process comes from water gas, a mixture of hydrogen and carbon monoxide.","feedback":"Misconception: A catalyst supplies atoms to the product."}},"explanation":"Book (pp.6-7): iron is used as a catalyst in the manufacture of ammonia by the Haber-Bosch method, and in the conversion of water gas (a mixture of hydrogen and carbon monoxide) to a fuel by the Fischer-Tropsch method. A catalyst speeds up the reaction and is not used up. Water gas is not water vapour: it is a mixture of CO and $\\ce{H2}$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ catalyst بيسرّع التفاعل ومش بيتستهلك."},"b":{"why":"الـ water gas مش بخار مية: ده خليط من غازين، الـ hydrogen والـ carbon monoxide.","feedback":"الفكرة الغلط: إن الـ water gas هو بخار المية."},"c":{"why":"الـ catalyst مابيخلصش أثناء التفاعل: كتلته في الآخر بتبقى زي ما هي، فمش محتاج iron جديد كل مرة.","feedback":"الفكرة الغلط: إن الـ catalyst بيتستهلك في التفاعل."},"d":{"why":"الـ iron مفيهوش hydrogen يدّيه. الـ hydrogen في العملية دي جاي من الـ water gas نفسه.","feedback":"الفكرة الغلط: إن الـ catalyst بيدّي ذرات للناتج."}},"explanation":"الكتاب (pp.6-7): الـ iron بيتستخدم كـ catalyst في تحضير الـ ammonia بطريقة الـ Haber-Bosch، وفي تحويل الـ water gas (خليط من الـ hydrogen والـ carbon monoxide) لـ fuel بطريقة الـ Fischer-Tropsch. الـ catalyst بيسرّع التفاعل ومش بيتستهلك. والـ water gas مش بخار مية: ده خليط من CO و $\\ce{H2}$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":58,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-ni-1","kind":"question","version":1,"ord":147,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-ni","concepts":[{"concept_id":"te.uses-ni","role":"primary"}],"title":"chem-s3-en.question-te.uses-ni-1","payload":{"stem":"Choose the statement that gives a use of nickel with its correct reason, according to the book.","tags":["exam-style","choose","reasons"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Nickel-chromium alloys are used in heating coils, because they resist corrosion at high temperature.","correct":true},{"id":"b","text":"Nickel-chromium alloys are used in heating coils, because they are the best conductors of electricity.","correct":false},{"id":"c","text":"Nickel-cadmium batteries are used, because they cannot be recharged and so last longer.","correct":false},{"id":"d","text":"Nickel plating is used to make other metals lighter.","correct":false}],"book_ref":"Ch.1 economic importance: 8-Nickel, p.7","difficulty":3,"concept_ids":["te.uses-ni"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! That is the book's reason."},"b":{"why":"The coils get very hot in air for years, so what they must resist is corrosion at high temperature; conductivity is not the book's reason.","feedback":"Misconception: Ni-Cr coils are chosen because they conduct well."},"c":{"why":"A Ni-Cd battery can be recharged again and again, so 'cannot be recharged' is wrong.","feedback":"Misconception: Ni-Cd batteries are single-use."},"d":{"why":"A thin coat of nickel hardly changes the mass: it protects the metal from oxidation and rust and gives it a beautiful appearance.","feedback":"Misconception: Plating changes the metal's density."}},"explanation":"Book (p.7): nickel is used in the nickel-cadmium battery, which can be recharged. With steel it forms alloys that are hard and resist rust and the effect of acids. Nickel-chromium alloys are used in heating coils and electric furnaces because they resist corrosion at high temperature. Nickel plating protects other metals from oxidation and rust and gives them a beautiful appearance. Finely divided nickel is a catalyst in the hydrogenation of oils. Common mistake: 'Ni-Cr coils are used because they conduct well'. The book's reason is resistance to corrosion at high temperature."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! ده سبب الكتاب بالظبط."},"b":{"why":"الـ coils دي بتسخن جامد في الهوا لسنين، فلازم تقاوم الـ corrosion في درجة الحرارة العالية؛ ده سبب الكتاب، مش التوصيل.","feedback":"الفكرة الغلط: إن الـ Ni-Cr coils بتتختار عشان بتوصّل الكهربا كويس."},"c":{"why":"الـ Ni-Cd battery بتتشحن تاني، فالسبب ده عكس اللي في الكتاب.","feedback":"الفكرة الغلط: إن الـ Ni-Cd batteries بتتستخدم مرة واحدة وخلاص."},"d":{"why":"طبقة رقيقة من الـ nickel يدوب بتغيّر الكتلة. هي بتحمي الـ metal من الـ oxidation والـ rust وبتدّيه شكل جميل، مش بتخفّفه.","feedback":"الفكرة الغلط: إن الـ plating بيغيّر الـ density بتاعة الـ metal."}},"explanation":"الكتاب (p.7): الـ nickel بيتستخدم في الـ nickel-cadmium battery، اللي ممكن تتشحن تاني. ومع الـ steel بيكوّن alloys جامدة (hard) وبتقاوم الـ rust وتأثير الـ acids. والـ nickel-chromium alloys بتتستخدم في الـ heating coils والـ electric furnaces عشان بتقاوم الـ corrosion في درجة الحرارة العالية. والـ nickel plating بيحمي الـ metals التانية من الـ oxidation والـ rust وبيدّيها شكل جميل. والـ finely divided nickel بيبقى catalyst في الـ hydrogenation of oils. غلطة بتتكرر: إنك تقول إن الـ Ni-Cr coils بتتستخدم عشان بتوصّل كويس. سبب الكتاب هو مقاومة الـ corrosion في درجة الحرارة العالية."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":59,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-cu-zn-1","kind":"question","version":1,"ord":148,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-cu-zn","concepts":[{"concept_id":"te.uses-cu-zn","role":"primary"}],"title":"chem-s3-en.question-te.uses-cu-zn-1","payload":{"stem":"Choose the correct statement about copper.","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Copper is used in electric cables because it is a good conductor of electricity.","correct":true},{"id":"b","text":"Bronze is an alloy of copper and zinc.","correct":false},{"id":"c","text":"Copper is used to galvanize iron to protect it from rusting.","correct":false},{"id":"d","text":"Fehling solution, a copper compound, changes from orange to blue when it detects glucose.","correct":false}],"book_ref":"Ch.1 economic importance: 9-Copper, 10-Zinc, pp.7-8","difficulty":2,"concept_ids":["te.uses-cu-zn"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Correct! That is the book's reason."},"b":{"why":"The book makes bronze from copper and tin; zinc is not part of bronze.","feedback":"Misconception: Bronze is copper + zinc."},"c":{"why":"Galvanizing uses zinc, another element of the series, not copper.","feedback":"Misconception: Copper is used in galvanizing."},"d":{"why":"That reverses the book's colour change: Fehling solution is blue before it detects glucose, and it changes to orange.","feedback":"Misconception: Reversing the colour change of Fehling solution."}},"explanation":"Book (p.7): copper is a good conductor of electricity. So it is used in electric cables and in the coins industry. Copper is the first discovered metal. Copper-tin alloys are known as bronze; zinc is not part of bronze. Copper (II) sulphate, $CuSO_4$, is used as an insecticide and fungicide in the purification of water. Fehling solution (one of copper compounds) detects glucose: its blue colour changes to orange. Galvanizing other metals to protect them from rusting uses zinc, not copper."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! ده بالظبط السبب اللي في الكتاب."},"b":{"why":"الكتاب بيخلط الـ copper مع الـ tin عشان يعمل الـ bronze، مش مع الـ zinc.","feedback":"الفكرة الغلط: إن الـ bronze هو copper + zinc."},"c":{"why":"الـ galvanizing بيستخدم عنصر تاني من نفس السلسلة، الـ zinc، مش الـ copper.","feedback":"الفكرة الغلط: إن الـ copper بيتستخدم في الـ galvanizing."},"d":{"why":"كده إنت قلبت تغيّر اللون اللي في الكتاب: الـ Fehling solution لونه أزرق قبل ما يكشف الـ glucose، وبعدين بيتغيّر لبرتقاني.","feedback":"الفكرة الغلط: إنك تقلب اتجاه تغيّر اللون في الـ Fehling solution."}},"explanation":"الكتاب (ص 7): الـ copper هو good conductor of electricity، وعشان كده بيدخل في الكابلات الكهربا وفي صناعة العملات. والـ copper هو أول metal اتكشف. الـ alloys اللي من copper و tin اسمها bronze، والـ zinc مش داخل في الـ bronze. الـ Copper (II) sulphate، $CuSO_4$، بيتستخدم insecticide و fungicide في تنقية المية. والـ Fehling solution (واحد من compounds الـ copper) بيكشف الـ glucose: لونه الأزرق بيتغيّر لبرتقاني. أما الـ galvanizing للـ metals التانية عشان تتحمي من الصدأ فبيستخدم الـ zinc، مش الـ copper."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":60,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-sc-ti-2","kind":"question","version":1,"ord":149,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-sc-ti","concepts":[{"concept_id":"te.uses-sc-ti","role":"primary"}],"title":"chem-s3-en.question-te.uses-sc-ti-2","payload":{"stem":"A dentist needs a metal for a dental implant that will stay in the jawbone for many years. The table describes three metals P, Q and R. Using the book's reasoning for titanium, which metal is the best choice?","tags":["exam-style","choose","data","new-case"],"type":"mcq","bloom":"apply","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["P","very hard","reacts slowly with body fluids; its ions are toxic","high"],["Q","as rigid as steel","inert; the body does not reject it","less than steel"],["R","soft","inert; the body does not reject it","low"]],"caption":"Three metals considered for a dental implant (data for illustration)","headers":["Metal","Rigidity","Behaviour in the human body","Density"]},"children":[]}}},"choices":[{"id":"a","text":"Q, because it is inert and rigid","correct":true},{"id":"b","text":"P, because it is the hardest of the three","correct":false},{"id":"c","text":"R, because it is inert and the lightest","correct":false},{"id":"d","text":"P, because it reacts with body fluids and bonds to bone","correct":false}],"book_ref":"Ch.1 economic importance: 1-Scandium, 2-Titanium, p.5 (fig 1-2); reason for dental implants and artificial joints","difficulty":4,"concept_ids":["te.uses-sc-ti"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Correct! Q behaves like titanium: inert, rigid and less dense than steel."},"b":{"why":"P is the hardest, but its row says it reacts with body fluids and its ions are toxic, which would cause poisoning over many years.","feedback":"Misconception: Titanium is used in implants because it is hard."},"c":{"why":"Being inert is good, but an implant must carry the force of chewing, and a soft metal is not rigid enough.","feedback":"Misconception: Being inert is the only condition; strength does not matter."},"d":{"why":"The book says a metal for implants must not cause any poisoning, and P's row says its ions are toxic.","feedback":"Misconception: A metal that reacts with the body fixes better."}},"explanation":"The book (p.5) says titanium is used in dental implants and artificial joints because it is an inert substance, so the body does not eject (reject) it and it does not cause any type of poisoning. Titanium is also as rigid as steel but less dense. Metal Q has exactly these properties, so it is the best choice. P is very hard, but it reacts with body fluids and releases toxic ions, so it fails the 'no poisoning' condition. R is inert, but soft, so it cannot carry the force of chewing. Common mistake: choosing by hardness alone. Rigidity matters, but the book's reason for implants is that titanium is inert."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ Q بيتصرف زي الـ titanium: inert، وجامد، وكثافته أقل من الـ steel."},"b":{"why":"الـ P هو الأصلب، لكن الصف بتاعه بيقول إنه بيطلّع ions سامة، ودي هتأذي الجسم على مدى سنين كتير.","feedback":"الفكرة الغلط: إن الـ titanium بيستخدم في الزراعة جوه الجسم عشان هو صلب."},"c":{"why":"إنه inert ده كويس، لكن الزرعة لازم تستحمل قوة المضغ، والـ metal الطري مش هيبقى جامد كفاية.","feedback":"الفكرة الغلط: إن كونه inert هو الشرط الوحيد، والقوة مش فارقة."},"d":{"why":"الكتاب بيقول إن الـ metal اللي بيتزرع لازم مايعملش أي تسمم، والصف بتاع الـ P بيقول إن الـ ions بتاعته سامة.","feedback":"الفكرة الغلط: إن الـ metal اللي بيتفاعل مع الجسم بيثبت أحسن."}},"explanation":"الكتاب (ص 5) بيقول إن الـ titanium بيستخدم في زراعة الأسنان والمفاصل الصناعية لأنه inert substance، فالجسم مابيطردوش (مابيرفضوش) ومابيعملش أي نوع من التسمم. وكمان الـ titanium جامد زي الـ steel لكن كثافته أقل. الـ metal Q فيه الصفات دي بالظبط، فهو أحسن اختيار. الـ P صلب جدًا، لكنه بيتفاعل مع سوائل الجسم وبيطلّع ions سامة، فمش بيحقق شرط «مفيش تسمم». والـ R inert لكنه طري، فمش هيستحمل قوة المضغ. غلطة بتتكرر: إنك تختار على أساس الصلابة لوحدها. إنه يكون جامد ده مهم، لكن سبب الكتاب للزراعة إن الـ titanium inert."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":61,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-v-cr-2","kind":"question","version":1,"ord":150,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-v-cr","concepts":[{"concept_id":"te.uses-v-cr","role":"primary"}],"title":"chem-s3-en.question-te.uses-v-cr-2","payload":{"stem":"Choose the correct answer: Which of the following is a use of chromium metal itself, not of one of its compounds?","tags":["exam-style","choose","element-vs-compound"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Plating other metals","correct":true},{"id":"b","text":"Manufacture of dyes","correct":false},{"id":"c","text":"Acting as an oxidizing agent","correct":false},{"id":"d","text":"Manufacture of car springs","correct":false}],"book_ref":"Ch.1 economic importance: 3-Vanadium, 4-Chromium, p.6","difficulty":3,"concept_ids":["te.uses-v-cr"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Correct! Chromium metal is used in metal plating."},"b":{"why":"Dyes come from a chromium compound, chromium (III) oxide, not from the metal itself.","feedback":"Misconception: Giving the use of $Cr_2O_3$ to chromium metal."},"c":{"why":"The book names potassium dichromate, a chromium compound, as the oxidizing agent, not the metal.","feedback":"Misconception: Giving the use of $K_2Cr_2O_7$ to chromium metal."},"d":{"why":"Car springs are made with vanadium added to steel, not chromium.","feedback":"Misconception: Mixing up chromium with vanadium."}},"explanation":"Book (p.6): chromium (the metal) is used in metal plating and leather tanning. Its compounds: chromium (III) oxide, $Cr_2O_3$, is used in the manufacture of dyes, and potassium dichromate, $K_2Cr_2O_7$, is used as an oxidizing agent. Car springs are made of steel with a little vanadium. Chromium plating works because chromium resists the effect of the atmosphere: a non-porous oxide layer covers it."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ chromium الـ metal بيتستخدم في الـ metal plating."},"b":{"why":"الـ dyes بتيجي من compound للـ chromium، الـ chromium (III) oxide، مش من الـ metal نفسه.","feedback":"الفكرة الغلط: إنك تدي استخدام الـ $Cr_2O_3$ للـ chromium الـ metal."},"c":{"why":"الـ oxidizing agent هو compound للـ chromium، الـ potassium dichromate، مش الـ metal نفسه.","feedback":"الفكرة الغلط: إنك تدي استخدام الـ $K_2Cr_2O_7$ للـ chromium الـ metal."},"d":{"why":"الـ car springs بتتعمل بعنصر تاني بيتضاف للـ steel، الـ vanadium، مش الـ chromium.","feedback":"الفكرة الغلط: إنك تخلط بين الـ chromium والـ vanadium."}},"explanation":"الكتاب (p.6): الـ chromium (الـ metal) بيتستخدم في الـ metal plating والـ leather tanning. أما الـ compounds بتاعته: الـ chromium (III) oxide، $Cr_2O_3$، بيتستخدم في صناعة الـ dyes، والـ potassium dichromate، $K_2Cr_2O_7$، بيتستخدم كـ oxidizing agent. والـ car springs معمولة من steel فيه شوية vanadium. والـ chromium plating بينفع عشان الـ chromium بيقاوم تأثير الـ atmosphere: بتغطيه طبقة oxide تكون non-porous."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":62,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.chromium-oxide-layer-2","kind":"question","version":1,"ord":151,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.chromium-oxide-layer","concepts":[{"concept_id":"te.chromium-oxide-layer","role":"primary"}],"title":"chem-s3-en.question-te.chromium-oxide-layer-2","payload":{"stem":"Choose the correct answer: The oxide layer formed on the surface of chromium protects the metal, because ...","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"the molecular volume of the oxide is larger than that of the metal atoms, so the layer is non-porous","correct":true},{"id":"b","text":"the molecular volume of the oxide is smaller than that of the metal atoms, so the layer is packed tightly","correct":false},{"id":"c","text":"the oxide layer is porous, so air passes through it without reacting","correct":false},{"id":"d","text":"chromium is an inactive metal, so its oxide forms very slowly","correct":false}],"book_ref":"Ch.1 economic importance: 4-Chromium, p.6; form of Evaluation Q7 (give reasons), p.27","difficulty":2,"concept_ids":["te.chromium-oxide-layer"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! A larger oxide covers the whole surface with no gaps."},"b":{"why":"An oxide that took up less room than the metal it came from would leave gaps, not cover the whole surface.","feedback":"Misconception: A smaller oxide packs more tightly."},"c":{"why":"A porous layer lets air and moisture through to the metal below, like rust on iron.","feedback":"Misconception: A porous layer protects."},"d":{"why":"The book calls chromium a chemically active metal; the reaction stops because of the layer, not low activity.","feedback":"Misconception: Chromium resists air because it is unreactive."}},"explanation":"Book (p.6): chromium is a chemically active metal, but it resists the effect of atmospheric air, because the molecular volume of the oxide formed on its surface is larger than that of the metal atoms. So the oxide forms a non-porous layer that prevents the continued interaction with the oxygen of air. A smaller oxide would leave gaps; a porous layer (like rust) lets air and moisture reach the metal."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ oxide الأكبر بيغطّي السطح كله من غير فراغات."},"b":{"why":"لو الـ oxide واخد مساحة أقل من الـ metal اللي جه منه، كان هيسيب فراغات ومش هيغطّي السطح كله.","feedback":"الفكرة الغلط: إن الـ oxide الأصغر بيترصّ أكتر."},"c":{"why":"الطبقة الـ porous بتعدّي الهوا والرطوبة للـ metal اللي تحتها، زي الـ rust على الـ iron.","feedback":"الفكرة الغلط: إن الطبقة الـ porous بتحمي."},"d":{"why":"الكتاب بيقول إن الـ chromium ده chemically active metal؛ التفاعل بيقف بسبب الطبقة، مش عشان نشاطه قليل.","feedback":"الفكرة الغلط: إن الـ chromium بيقاوم الهوا عشان هو unreactive."}},"explanation":"الكتاب (ص 6): الـ chromium ده chemically active metal، لكنه بيقاوم تأثير الهوا الجوي، عشان الـ molecular volume بتاع الـ oxide اللي بيتكوّن على سطحه أكبر من بتاع ذرات الـ metal. فالـ oxide بيعمل طبقة non-porous بتمنع إن التفاعل مع الـ oxygen اللي في الهوا يكمّل. الـ oxide الأصغر كان هيسيب فراغات؛ والطبقة الـ porous (زي الـ rust) بتسيب الهوا والرطوبة يوصلوا للـ metal."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":63,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-mn-2","kind":"question","version":1,"ord":152,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-mn","concepts":[{"concept_id":"te.uses-mn","role":"primary"}],"title":"chem-s3-en.question-te.uses-mn-2","payload":{"stem":"Choose the correct answer: In the dry cell, manganese dioxide ($MnO_2$) acts as ...","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"a strong oxidizing agent","correct":true},{"id":"b","text":"a catalyst","correct":false},{"id":"c","text":"a reducing agent","correct":false},{"id":"d","text":"an antiseptic substance","correct":false}],"book_ref":"Ch.1 economic importance: 5-Manganese, p.6","difficulty":3,"concept_ids":["te.uses-mn"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! That is its role in the dry cell."},"b":{"why":"You may have met $MnO_2$ as a catalyst that speeds up the decomposition of hydrogen peroxide, but that is a different reaction, not its role in the dry cell.","feedback":"Misconception: $MnO_2$ is always a catalyst."},"c":{"why":"$MnO_2$ gives oxygen to other substances, and that is what an oxidizing agent does, not a reducing agent.","feedback":"Misconception: Mixing up oxidizing and reducing agents."},"d":{"why":"The book links the antiseptic use to a different manganese compound, potassium permanganate.","feedback":"Misconception: Mixing up $MnO_2$ with $KMnO_4$."}},"explanation":"Book (p.6): manganese dioxide, $MnO_2$, acts as a strong oxidizing agent used in dry cell. Potassium permanganate, $KMnO_4$, is the antiseptic substance. Manganese II sulphate, $MnSO_4$, is the fungicide. You may have met $MnO_2$ as a catalyst in the decomposition of hydrogen peroxide. That is a different reaction. In the dry cell, the book gives it the role of an oxidizing agent."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! ده دوره في الـ dry cell."},"b":{"why":"ممكن تكون قابلت الـ $MnO_2$ كـ catalyst بيسرّع تحلّل الـ hydrogen peroxide، لكن ده تفاعل تاني، ومش ده دوره في الـ dry cell.","feedback":"الفكرة الغلط: إن الـ $MnO_2$ دايمًا catalyst."},"c":{"why":"الـ $MnO_2$ بيدّي oxygen للمواد التانية، والـ agent اللي بيعمل كده اسمه oxidizing agent، مش reducing agent.","feedback":"الفكرة الغلط: إنك تلخبط بين الـ oxidizing agent والـ reducing agent."},"d":{"why":"الكتاب بيربط استخدام الـ antiseptic بـ compound تاني فيه manganese، الـ potassium permanganate، مش الـ manganese dioxide.","feedback":"الفكرة الغلط: إنك تلخبط بين الـ $MnO_2$ والـ $KMnO_4$."}},"explanation":"الكتاب (ص 6): الـ manganese dioxide، $MnO_2$، بيشتغل strong oxidizing agent بيُستخدم في الـ dry cell. والـ potassium permanganate، $KMnO_4$، هو الـ antiseptic substance. والـ manganese II sulphate، $MnSO_4$، هو الـ fungicide. ممكن تكون قابلت الـ $MnO_2$ كـ catalyst في تحلّل الـ hydrogen peroxide، لكن ده تفاعل تاني خالص. في الـ dry cell الكتاب بيديله دور الـ oxidizing agent."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":64,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-fe-co-2","kind":"question","version":1,"ord":153,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-fe-co","concepts":[{"concept_id":"te.uses-fe-co","role":"primary"}],"title":"chem-s3-en.question-te.uses-fe-co-2","payload":{"stem":"Choose the correct answer: Cobalt-60 is used in food preserving and in the treatment of tumours, because it ...","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"produces gamma rays, which have high penetrating power","correct":true},{"id":"b","text":"can be magnetized, like iron","correct":false},{"id":"c","text":"produces ultraviolet rays, which cannot pass through matter","correct":false},{"id":"d","text":"is a stable isotope that never changes","correct":false}],"book_ref":"Ch.1 economic importance: 6-Iron, 7-Cobalt (printed '27-Cobalt'), pp.6-7","difficulty":2,"concept_ids":["te.uses-fe-co"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Its gamma rays pass deep into matter."},"b":{"why":"Being magnetized explains cobalt's use in magnets; a radioactive isotope gives out rays, and cobalt-60 gives out gamma rays.","feedback":"Misconception: Cobalt-60 is used because cobalt is magnetic."},"c":{"why":"UV hardly gets through the skin, so it could not reach a tumour deep in the body.","feedback":"Misconception: Cobalt-60 gives UV rays."},"d":{"why":"The book says cobalt has twelve radioactive isotopes and names cobalt-60 among them; a stable isotope does not give out rays.","feedback":"Misconception: Cobalt-60 is stable."}},"explanation":"Book (p.7): cobalt has twelve radioactive isotopes; cobalt-60 is a very important one because it produces gamma rays, which have high penetrating power. So it is used in food preserving, to check the quality of industrial products, to detect cracks and welding connections, and in medicine for the diagnosis and treatment of tumours. Cobalt's magnetic property is a different use: like iron, it can be magnetized, so it is used to make magnets."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ gamma rays بتاعته بتخترق المادة لعمق كبير."},"b":{"why":"إن الـ cobalt بيتمغنط ده بيفسّر استخدامه في الـ magnets، مش في الـ food preserving وعلاج الأورام: الاستخدامين دول معتمدين على الأشعة اللي بيطلّعها الـ radioactive isotope.","feedback":"الفكرة الغلط: إن الـ Cobalt-60 بنستخدمه عشان الـ cobalt بيتمغنط."},"c":{"why":"الـ UV يدوب بيعدّي من الجلد، فمش هيوصل لورم جوه الجسم، والـ cobalt-60 مش بيطلّع UV.","feedback":"الفكرة الغلط: إن الـ Cobalt-60 بيطلّع UV rays."},"d":{"why":"الكتاب بيقول إن الـ cobalt ليه 12 radioactive isotopes، ومنهم الـ cobalt-60، فهو مش isotope مستقر. والـ isotope المستقر مابيطلّعش أشعة.","feedback":"الفكرة الغلط: إن الـ Cobalt-60 مستقر."}},"explanation":"الكتاب (p.7): الـ cobalt ليه 12 radioactive isotopes؛ والـ cobalt-60 واحد مهم جدًا منهم عشان بيطلّع gamma rays ليها high penetrating power. عشان كده بنستخدمه في food preserving، وفحص جودة المنتجات الصناعية، واكتشاف الشروخ ووصلات اللحام (cracks and welding connections)، وفي الطب لتشخيص الأورام وعلاجها. أما خاصية المغناطيسية فده استخدام تاني خالص: الـ cobalt زي الـ iron بيتمغنط، فبيتعمل منه magnets."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":65,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-ni-2","kind":"question","version":2,"catalog_version":1,"ord":154,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-ni","concepts":[{"concept_id":"te.uses-ni","role":"primary"},{"concept_id":"chem.catalyst","role":"secondary"}],"title":"chem-s3-en.question-te.uses-ni-2","payload":{"stem":"Two experiments hydrogenate the same amount of an oil, using the same mass of nickel as a catalyst. The results are shown in the table. Which conclusion is correct?","tags":["exam-style","data","new-case"],"type":"mcq","bloom":"analyze","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["one lump","60 min","5.0 g"],["finely divided powder","5 min","5.0 g"]],"caption":"Hydrogenation of an oil with nickel (data for illustration)","headers":["Form of nickel","Time for hydrogenation","Mass of nickel at the end"]},"children":[]}}},"choices":[{"id":"a","text":"The powder is faster because more of its surface meets the reactants; it is not used up","correct":true},{"id":"b","text":"The powder is faster because it reacts with the oil and is used up faster","correct":false,"misconception_id":"chem.catalyst.mc1"},{"id":"c","text":"Nickel is a reactant here, because changing its form changed the time","correct":false},{"id":"d","text":"The lump is better, because the nickel stays in one piece","correct":false,"misconception_id":"te.uses-ni.mc2"}],"book_ref":"Ch.1 economic importance: 8-Nickel, p.7","difficulty":4,"concept_ids":["te.uses-ni","chem.catalyst"],"est_seconds":100},"layer":{"choices":{"a":{"why":"Correct! Same mass, more surface, and no nickel lost."},"b":{"why":"The last column shows 5.0 g of nickel at the end of both experiments, so no nickel was used up.","feedback":"Misconception: The catalyst is consumed."},"c":{"why":"A reactant is used up, but the mass of nickel stayed 5.0 g in both experiments, so nickel is a catalyst.","feedback":"Misconception: Anything that changes the speed is a reactant."},"d":{"why":"With the same mass, the powder took 5 min and the lump 60 min, so the powder did the job faster.","feedback":"Misconception: A lump of nickel catalyses as well as finely divided nickel."}},"explanation":"Analyze the two columns. (1) Mass at the end: 5.0 g in both experiments. So nickel is not used up: it is a catalyst, not a reactant. (2) Time: the powder takes 5 min, the lump takes 60 min. With the same mass, the powder has a much larger surface area. The reactants meet the catalyst at its surface. More surface lets more reactant molecules react at the same time, so the reaction is faster. This is why the book uses finely divided nickel as a catalyst in hydrogenation processes of oil (p.7)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! نفس الكتلة، سطح أكبر، ومفيش nickel ضاع."},"b":{"why":"آخر عمود بيقول إن كتلة الـ nickel 5.0 g في التجربتين، فمفيش nickel اتستهلك.","feedback":"الفكرة الغلط: إن الـ catalyst بيتستهلك."},"c":{"why":"الـ reactant بيتستهلك، لكن كتلة الـ nickel ماتغيّرتش في أي تجربة، فالـ nickel هنا catalyst.","feedback":"الفكرة الغلط: إن أي حاجة بتغيّر السرعة تبقى reactant."},"d":{"why":"الـ powder خلّص الشغل في 5 min والـ lump في 60 min بنفس الكتلة، فالـ lump أبطأ بكتير.","feedback":"الفكرة الغلط: إن حتة nickel واحدة بتعمل catalysis زي الـ finely divided nickel بالظبط."}},"explanation":"حلّل العمودين. (1) الكتلة في الآخر: 5.0 g في التجربتين. يعني الـ nickel ماتستهلكش: هو catalyst مش reactant. (2) الوقت: الـ powder خد 5 min، والـ lump خد 60 min. بنفس الكتلة، الـ powder ليه مساحة سطح أكبر بكتير. والـ reactants بتقابل الـ catalyst عند سطحه. سطح أكبر يعني molecules أكتر من الـ reactants تقدر تتفاعل في نفس الوقت، فالتفاعل بيبقى أسرع. وعشان كده الكتاب بيستخدم الـ finely divided nickel كـ catalyst في عمليات الـ hydrogenation of oil (p.7)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":66,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":59,"page_to":59,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-cu-zn-2","kind":"question","version":1,"ord":155,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-cu-zn","concepts":[{"concept_id":"te.uses-cu-zn","role":"primary"}],"title":"chem-s3-en.question-te.uses-cu-zn-2","payload":{"stem":"Element X belongs to the first transition series. X is used in galvanizing other metals to protect them from rusting. Its oxide is used in the manufacture of paints, rubber and cosmetics, and its sulphide in X-ray screens. Which is the electronic configuration of X?\n(Atomic numbers: Cr = 24, Ni = 28, Cu = 29, Zn = 30)","tags":["exam-style","two-step","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$[Ar]\\,4s^2\\,3d^{10}$","correct":true},{"id":"b","text":"$[Ar]\\,4s^1\\,3d^{10}$","correct":false},{"id":"c","text":"$[Ar]\\,4s^2\\,3d^8$","correct":false},{"id":"d","text":"$[Ar]\\,4s^1\\,3d^5$","correct":false}],"book_ref":"Ch.1 economic importance: 9-Copper, 10-Zinc, pp.7-8","difficulty":4,"concept_ids":["te.uses-cu-zn"],"est_seconds":100},"layer":{"choices":{"a":{"why":"Correct! X is zinc, $_{30}$Zn."},"b":{"why":"This configuration belongs to copper, the metal used in electric cables; galvanizing uses zinc.","feedback":"Misconception: Mixing up zinc with copper."},"c":{"why":"Nickel plating also protects metals from rust, but it is not galvanizing; the oxide used in paints and cosmetics is zinc oxide.","feedback":"Misconception: Nickel plating is the same as galvanizing."},"d":{"why":"Chromium is used in plating, not galvanizing; the sulphide used in X-ray screens is zinc sulphide.","feedback":"Misconception: Chromium plating is the same as galvanizing."}},"explanation":"Step 1: identify X from its uses (book pp.7-8). X is used in galvanizing other metals to protect them from rusting. Zinc oxide, ZnO, is used in paints, rubber and cosmetics. Zinc sulphide, ZnS, is used in illuminating paints and X-ray screens. So X is zinc, atomic number 30. Step 2: write its configuration. After argon (18 electrons), 12 electrons remain. Two fill 4s, then ten fill 3d: $[Ar]\\,4s^2\\,3d^{10}$. Nickel and chromium also coat other metals; copper is the element next to zinc, used in electric cables. $[Ar]\\,4s^1\\,3d^{10}$ is copper. Copper's real configuration differs from the expected one; you will study why later in this chapter. $[Ar]\\,4s^2\\,3d^8$ is nickel, used for plating other metals. $[Ar]\\,4s^1\\,3d^5$ is chromium, used in metal plating."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ X هو الـ zinc، $_{30}$Zn."},"b":{"why":"الـ configuration دي بتاعة الـ copper، الـ metal اللي بيتعمل منه الكابلات الكهربا، والـ galvanizing بيستخدم عنصر تاني.","feedback":"الفكرة الغلط: إنك تخلط بين الـ zinc والـ copper."},"c":{"why":"الـ configuration دي بتاعة الـ nickel. الطلا بالـ nickel كمان بيحمي الـ metals من الصدأ، لكنه مش galvanizing، والـ oxide اللي بيدخل في الدهانات ومستحضرات التجميل بتاع عنصر تاني.","feedback":"الفكرة الغلط: إن الطلا بالـ nickel هو نفسه الـ galvanizing."},"d":{"why":"الـ configuration دي بتاعة الـ chromium، وده بيتستخدم في الطلا، مش في الـ galvanizing، والـ sulphide اللي بيدخل في شاشات الـ X-ray بتاع عنصر تاني.","feedback":"الفكرة الغلط: إن الطلا بالـ chromium هو نفسه الـ galvanizing."}},"explanation":"الخطوة 1: اعرف الـ X من استخداماته (الكتاب ص 7-8). الـ X بيتعمل بيه galvanizing للـ metals التانية عشان يحميها من الصدأ. الـ Zinc oxide، ZnO، بيدخل في الدهانات والمطاط ومستحضرات التجميل. والـ Zinc sulphide، ZnS، بيدخل في الدهانات المضيئة وشاشات الـ X-ray. يبقى الـ X هو الـ zinc، والـ atomic number بتاعه 30. الخطوة 2: اكتب الـ configuration بتاعته. بعد الـ argon (18 electrons) بيفضل 12 electrons. اتنين بيملوا الـ 4s، وبعدين عشرة بيملوا الـ 3d: $[Ar]\\,4s^2\\,3d^{10}$. الـ nickel والـ chromium كمان بيتطلى بيهم metals تانية؛ والـ copper هو العنصر اللي جنب الـ zinc، وبيتعمل منه الكابلات الكهربا. الـ $[Ar]\\,4s^1\\,3d^{10}$ دي بتاعة الـ copper، والـ configuration الحقيقية للـ copper مختلفة عن المتوقع؛ وهتدرس السبب بعدين في الفصل ده. الـ $[Ar]\\,4s^2\\,3d^8$ دي الـ nickel، اللي بيتستخدم في طلا الـ metals التانية. والـ $[Ar]\\,4s^1\\,3d^5$ دي الـ chromium، اللي بيتستخدم في طلا الـ metals."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":67,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-sc-ti-3","kind":"question","version":2,"ord":156,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-sc-ti","concepts":[{"concept_id":"te.uses-sc-ti","role":"primary"}],"title":"chem-s3-en.question-te.uses-sc-ti-3","payload":{"stem":"Match each material in column (A) with its use in column (B).","tags":["exam-style","match"],"type":"match","bloom":"remember","answer":[["l1","r1"],["l2","r2"],["l3","r3"],["l4","r4"]],"choices":[{"id":"l1","text":"Scandium added to mercury vapour lamps"},{"id":"l2","text":"Titanium-aluminum alloys"},{"id":"l3","text":"Titanium metal"},{"id":"l4","text":"Titanium dioxide ($\\ce{TiO2}$) nanoparticles"},{"id":"r1","text":"Light like sunlight for TV photography at night"},{"id":"r2","text":"Aircraft and space shuttles"},{"id":"r3","text":"Dental implants and artificial joints"},{"id":"r4","text":"Sun protection cosmetics"}],"book_ref":"Ch.1 economic importance: 1-Scandium, 2-Titanium, p.5 (fig 1-2)","difficulty":2,"concept_ids":["te.uses-sc-ti"],"est_seconds":60},"layer":{"choices":{"l1":{"why":"Scandium is added to mercury vapour lamps to produce high-quality light like sunlight, used in TV photography at night."},"l2":{"why":"Titanium-aluminum alloys are used in aircraft and space shuttles: titanium maintains its durability at high temperatures, while the hardness of aluminum decreases."},"l3":{"why":"Titanium metal is inert, so the body does not reject it: it is used in dental implants and artificial joints."},"l4":{"why":"$\\ce{TiO2}$ nanoparticles prevent the effect of UV on the skin, so they are used in sun protection cosmetics."},"r1":{"why":"Light like sunlight for TV photography at night comes from mercury vapour lamps with scandium added."},"r2":{"why":"Aircraft and space shuttles use titanium-aluminum alloys, which keep their durability at high temperatures."},"r3":{"why":"Dental implants and artificial joints use titanium metal, which is inert and causes no poisoning."},"r4":{"why":"Sun protection cosmetics contain the compound $\\ce{TiO2}$ as nanoparticles, not titanium metal."}},"explanation":"Book (p.5): (1) Scandium is added to mercury vapour lamps to produce light with high quality like sunlight. So it is used in TV photography at night. (2) Titanium-aluminum alloys are used in the manufacture of aircraft and space shuttles. Titanium maintains its durability at high temperatures, while the hardness of aluminum decreases. (3) Titanium metal is used in dental implants and artificial joints. It is inert, so the body does not reject it and it causes no poisoning. (4) $\\ce{TiO2}$ nanoparticles are used in sun protection cosmetics. They prevent the effect of UV on the skin. Common confusion: titanium metal and titanium dioxide. Sunscreen contains the compound $\\ce{TiO2}$, not the metal. Also keep apart the scandium-aluminum alloy, which is used in MiG fighter jets."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"l1":{"why":"الـ scandium بيتضاف للـ mercury vapour lamps عشان تدّي ضوء عالي الجودة شبه ضوء الشمس، بيستخدموه في التصوير التلفزيوني بالليل."},"l2":{"why":"الـ titanium-aluminum alloys بتستخدم في الطيارات ومكوكات الفضاء: الـ titanium بيحافظ على متانته في درجات الحرارة العالية، في حين إن صلابة الـ aluminum بتقل."},"l3":{"why":"الـ titanium metal هو inert، فالجسم مابيرفضوش: عشان كده بيستخدم في زراعة الأسنان والمفاصل الصناعية."},"l4":{"why":"الـ $\\ce{TiO2}$ nanoparticles بتمنع تأثير الـ UV على الجلد، فبتستخدم في كريمات الحماية من الشمس."},"r1":{"why":"الضوء اللي شبه ضوء الشمس للتصوير التلفزيوني بالليل جاي من الـ mercury vapour lamps اللي متضاف لها scandium."},"r2":{"why":"الطيارات ومكوكات الفضاء بتستخدم الـ titanium-aluminum alloys، اللي بتحافظ على متانتها في درجات الحرارة العالية."},"r3":{"why":"زراعة الأسنان والمفاصل الصناعية بتستخدم الـ titanium metal، لأنه inert ومابيعملش تسمم."},"r4":{"why":"كريمات الحماية من الشمس فيها الـ compound $\\ce{TiO2}$ على شكل nanoparticles، مش الـ titanium metal."}},"explanation":"الكتاب (ص 5): (1) الـ scandium بيتضاف للـ mercury vapour lamps عشان تدّي ضوء عالي الجودة شبه ضوء الشمس، وعشان كده بيستخدموه في التصوير التلفزيوني بالليل. (2) الـ titanium-aluminum alloys بتستخدم في صناعة الطيارات ومكوكات الفضاء، لأن الـ titanium بيحافظ على متانته في درجات الحرارة العالية، في حين إن صلابة الـ aluminum بتقل. (3) الـ titanium metal بيستخدم في زراعة الأسنان والمفاصل الصناعية، لأنه inert، فالجسم مابيرفضوش ومابيعملش تسمم. (4) الـ $\\ce{TiO2}$ nanoparticles بتستخدم في كريمات الحماية من الشمس، لأنها بتمنع تأثير الـ UV على الجلد. خلط بيحصل كتير: الـ titanium metal والـ titanium dioxide. كريم الحماية من الشمس فيه الـ compound $\\ce{TiO2}$، مش الـ metal. وكمان افصل بينهم وبين الـ scandium-aluminum alloy اللي بيستخدم في طيارات الـ MiG الحربية."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":68,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-v-cr-3","kind":"question","version":2,"ord":157,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-v-cr","concepts":[{"concept_id":"te.uses-v-cr","role":"primary"},{"concept_id":"redox.basic","role":"secondary"}],"title":"chem-s3-en.question-te.uses-v-cr-3","payload":{"stem":"Potassium dichromate ($K_2Cr_2O_7$) is used as an oxidizing agent. In a reaction, it changes a substance Y into YO (Y gains oxygen). Which choice describes both changes correctly?","tags":["exam-style","two-step","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Y is oxidized; $K_2Cr_2O_7$ is reduced","correct":true},{"id":"b","text":"Y is reduced; $K_2Cr_2O_7$ is oxidized","correct":false},{"id":"c","text":"Y is oxidized; $K_2Cr_2O_7$ is oxidized too","correct":false},{"id":"d","text":"Y is reduced; $K_2Cr_2O_7$ is reduced too","correct":false}],"book_ref":"Ch.1 economic importance: 3-Vanadium, 4-Chromium, 5-Manganese, p.6 (K2Cr2O7 and MnO2 as oxidizing agents)","difficulty":3,"concept_ids":["te.uses-v-cr","redox.basic"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Correct! The oxidizing agent supplies the oxygen and is itself reduced."},"b":{"why":"Y gains oxygen, and gain of oxygen is oxidation, not reduction.","feedback":"Misconception: Gain of oxygen is reduction."},"c":{"why":"Y gains oxygen, so Y is oxidized, but its new oxygen came from $K_2Cr_2O_7$, and losing oxygen means that substance is reduced.","feedback":"Misconception: The oxidizing agent is itself oxidized."},"d":{"why":"Both substances cannot lose oxygen at the same time: Y gains oxygen, so Y is oxidized.","feedback":"Misconception: Oxidation and reduction do not need each other."}},"explanation":"Step 1: Y → YO. Y gains oxygen, so Y is oxidized. Step 2: the oxygen came from $K_2Cr_2O_7$. The oxidizing agent supplies oxygen (it oxidizes the other substance), so it is itself reduced. Oxidation and reduction always happen together. That is the meaning of the book's phrase 'potassium dichromate is used as an oxidizing agent' (p.6). The same idea explains $MnO_2$, a strong oxidizing agent in the dry cell."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ oxidizing agent هو اللي بيدّي الـ oxygen، وهو نفسه بيحصل له reduction."},"b":{"why":"الـ Y اكتسب oxygen، واكتساب الـ oxygen ده oxidation مش reduction.","feedback":"الفكرة الغلط: إن اكتساب الـ oxygen يبقى reduction."},"c":{"why":"الـ Y اكتسب oxygen، يبقى Y حصل له oxidation، لكن الـ oxygen الجديد ده جه من $K_2Cr_2O_7$، وفقدان الـ oxygen معناه إن المادة دي حصل لها reduction، مش oxidation.","feedback":"الفكرة الغلط: إن الـ oxidizing agent نفسه بيحصل له oxidation."},"d":{"why":"المادتين الاتنين مش ممكن يفقدوا oxygen في نفس الوقت، والـ Y هنا اكتسب oxygen، يعني حصل له oxidation.","feedback":"الفكرة الغلط: إن الـ oxidation والـ reduction مش محتاجين بعض."}},"explanation":"الخطوة 1: Y → YO. الـ Y اكتسب oxygen، يبقى Y حصل له oxidation. الخطوة 2: الـ oxygen ده جه من $K_2Cr_2O_7$. الـ oxidizing agent بيدّي oxygen (يعني بيعمل oxidation للمادة التانية)، فهو نفسه بيحصل له reduction. الـ oxidation والـ reduction دايمًا بيحصلوا مع بعض. وده معنى جملة الكتاب 'potassium dichromate is used as an oxidizing agent' (p.6). ونفس الفكرة بتفسّر الـ $MnO_2$، اللي هو strong oxidizing agent في الـ dry cell."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":69,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":84,"page_to":84,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.chromium-oxide-layer-3","kind":"question","version":1,"ord":158,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.chromium-oxide-layer","concepts":[{"concept_id":"te.chromium-oxide-layer","role":"primary"}],"title":"chem-s3-en.question-te.chromium-oxide-layer-3","payload":{"stem":"Consider the following statements about chromium in air:\n(I) Chromium resists the effect of the atmosphere because it does not react with oxygen.\n(II) The oxide layer on the surface of chromium is non-porous.\n(III) The oxide layer stops the continued interaction of chromium with the oxygen of air.\nWhich of these statements is/are correct?","tags":["exam-style","statements-I-II-III"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"II and III only","correct":true},{"id":"b","text":"I and II only","correct":false},{"id":"c","text":"I, II and III","correct":false},{"id":"d","text":"II only","correct":false}],"book_ref":"Ch.1 economic importance: 4-Chromium, p.6; form of Evaluation Q7 (give reasons), p.27","difficulty":3,"concept_ids":["te.chromium-oxide-layer"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Correct! Chromium does react, but its non-porous oxide stops further reaction."},"b":{"why":"(I) is wrong: if chromium did not react with oxygen, no oxide layer could form. (III) is also correct.","feedback":"Misconception: Chromium resists air because it does not react with oxygen."},"c":{"why":"(I) is wrong: if chromium never reacted with oxygen, no oxide layer could form on it.","feedback":"Misconception: Chromium is an inactive metal."},"d":{"why":"(II) is fine, but (III) is also correct: a non-porous layer stops further interaction with the oxygen of air.","feedback":"Misconception: A non-porous layer does not stop the reaction."}},"explanation":"(I) Wrong: the book says chromium is a chemically active metal. It does react with oxygen; that reaction is what forms the oxide layer. (II) Correct: the molecular volume of the oxide is larger than that of the metal atoms, so the layer is non-porous. (III) Correct: this non-porous layer prevents the continued interaction of the metal with the oxygen of air. Answer: II and III only. Key idea: chromium resists the atmosphere because of its oxide layer, not because it is unreactive."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ chromium بيتفاعل فعلًا، لكن الـ oxide الـ non-porous بتاعه بيوقّف أي تفاعل بعد كده."},"b":{"why":"(I) غلط: لو الـ chromium مابيتفاعلش مع الـ oxygen، ماكانتش أي oxide layer هتتكوّن. و(III) كمان صح.","feedback":"الفكرة الغلط: إن الـ chromium بيقاوم الهوا عشان مابيتفاعلش مع الـ oxygen."},"c":{"why":"(I) غلط: لو الـ chromium عمره ما اتفاعل مع الـ oxygen، ماكانتش أي oxide layer هتتكوّن عليه.","feedback":"الفكرة الغلط: إن الـ chromium ده inactive metal."},"d":{"why":"(II) تمام، لكن (III) كمان صح: الطبقة الـ non-porous بتوقف تفاعل الـ metal مع oxygen الهوا.","feedback":"الفكرة الغلط: إن الطبقة الـ non-porous مابتوقّفش التفاعل."}},"explanation":"(I) غلط: الكتاب بيقول إن الـ chromium ده chemically active metal. هو بيتفاعل فعلًا مع الـ oxygen، والتفاعل ده هو اللي بيكوّن طبقة الـ oxide. (II) صح: الـ molecular volume بتاع الـ oxide أكبر من بتاع ذرات الـ metal، فالطبقة non-porous. (III) صح: الطبقة الـ non-porous دي بتمنع إن الـ metal يكمّل تفاعل مع الـ oxygen اللي في الهوا. الإجابة: II and III only. الفكرة الأساسية: الـ chromium بيقاوم الهوا الجوي بسبب طبقة الـ oxide بتاعته، مش عشان هو unreactive."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":70,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-mn-3","kind":"question","version":2,"ord":159,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-mn","concepts":[{"concept_id":"te.uses-mn","role":"primary"}],"title":"chem-s3-en.question-te.uses-mn-3","payload":{"stem":"Match each manganese compound or alloy in column (A) with its use in column (B).","tags":["exam-style","match"],"type":"match","bloom":"remember","answer":[["l1","r1"],["l2","r2"],["l3","r3"],["l4","r4"],["l5","r5"]],"choices":[{"id":"l1","text":"Manganese dioxide ($MnO_2$)"},{"id":"l2","text":"Potassium permanganate ($KMnO_4$)"},{"id":"l3","text":"Manganese (II) sulphate ($MnSO_4$)"},{"id":"l4","text":"Ferromanganese alloy"},{"id":"l5","text":"Aluminum-manganese alloy"},{"id":"r1","text":"Strong oxidizing agent in the dry cell"},{"id":"r2","text":"Antiseptic substance"},{"id":"r3","text":"Fungicide"},{"id":"r4","text":"Railway tracks"},{"id":"r5","text":"Soft-drink cans"}],"book_ref":"Ch.1 economic importance: 5-Manganese, p.6","difficulty":2,"concept_ids":["te.uses-mn"],"est_seconds":75},"layer":{"choices":{"l1":{"why":"Manganese dioxide acts as a strong oxidizing agent used in the dry cell (book p.6)."},"l2":{"why":"Potassium permanganate is used as an antiseptic substance (book p.6)."},"l3":{"why":"Manganese (II) sulphate is used as a fungicide (book p.6)."},"l4":{"why":"Ferromanganese alloy is used in railway tracks because it is harder than steel."},"l5":{"why":"Aluminum and manganese alloys are used to make soft-drink cans because they resist corrosion."},"r1":{"why":"The strong oxidizing agent in the dry cell is manganese dioxide."},"r2":{"why":"The antiseptic substance is potassium permanganate, not the sulphate."},"r3":{"why":"The fungicide is manganese (II) sulphate, not potassium permanganate."},"r4":{"why":"Railway tracks need a material harder than steel: ferromanganese alloy."},"r5":{"why":"Soft-drink cans need a material that resists corrosion: the aluminum-manganese alloy."}},"explanation":"Book (p.6): $MnO_2$ → strong oxidizing agent in the dry cell; $KMnO_4$ → antiseptic substance; $MnSO_4$ → fungicide; ferromanganese → railway tracks (harder than steel); aluminum-manganese alloy → soft-drink cans (resists corrosion). Manganese itself is brittle, so it is only used in alloys and compounds. Common confusion: swapping $KMnO_4$ (antiseptic) and $MnSO_4$ (fungicide). Tip: '-sulphate' goes with 'fungicide', just like copper (II) sulphate, which is also a fungicide."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"l1":{"why":"الـ manganese dioxide بيشتغل strong oxidizing agent في الـ dry cell (الكتاب ص 6)."},"l2":{"why":"الـ potassium permanganate بيتستخدم antiseptic substance (الكتاب ص 6)."},"l3":{"why":"الـ manganese (II) sulphate بيتستخدم fungicide (الكتاب ص 6)."},"l4":{"why":"الـ ferromanganese alloy بيتستخدم في قضبان السكة الحديد لأنه أصلد من الـ steel."},"l5":{"why":"الـ alloys بتاعة الـ aluminum والـ manganese بتتستخدم في علب المياه الغازية لأنها بتقاوم الـ corrosion."},"r1":{"why":"الـ strong oxidizing agent اللي في الـ dry cell هو الـ manganese dioxide."},"r2":{"why":"الـ antiseptic substance هو الـ potassium permanganate، مش الـ sulphate."},"r3":{"why":"الـ fungicide هو الـ manganese (II) sulphate، مش الـ potassium permanganate."},"r4":{"why":"قضبان السكة الحديد محتاجة مادة أصلد من الـ steel: الـ ferromanganese alloy."},"r5":{"why":"علب المياه الغازية محتاجة مادة بتقاوم الـ corrosion: الـ aluminum-manganese alloy."}},"explanation":"الكتاب (ص 6): $MnO_2$ ← strong oxidizing agent في الـ dry cell؛ $KMnO_4$ ← antiseptic substance؛ $MnSO_4$ ← fungicide؛ الـ ferromanganese ← قضبان السكة الحديد (لأنه أصلد من الـ steel)؛ الـ aluminum-manganese alloy ← علب المياه الغازية (لأنه بيقاوم الـ corrosion). والـ manganese نفسه هش (brittle)، فبيُستخدم في alloys و compounds تحديدًا. غلطة بتتكرر: إنك تبدّل الـ $KMnO_4$ (antiseptic) بالـ $MnSO_4$ (fungicide). نصيحة: الـ '-sulphate' بيروح مع الـ 'fungicide'، زي الـ copper (II) sulphate اللي هو كمان fungicide."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":71,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-fe-co-3","kind":"question","version":2,"ord":160,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-fe-co","concepts":[{"concept_id":"te.uses-fe-co","role":"primary"},{"concept_id":"atom.isotopes","role":"secondary"},{"concept_id":"phys.radioactivity-gamma","role":"secondary"}],"title":"chem-s3-en.question-te.uses-fe-co-3","payload":{"stem":"A factory wants to check thick steel pipes for hidden cracks in their welding connections. A food company wants to preserve packed spices. Both plan to use cobalt-60.\nConsider the following statements:\n(I) Both uses depend on the gamma rays of cobalt-60, which can pass through thick materials.\n(II) The spices become radioactive after the treatment, so they cannot be eaten.\n(III) Cobalt-59 could replace cobalt-60, because it is an isotope of the same element.\nWhich of these statements is/are correct?","tags":["exam-style","statements-I-II-III","two-step","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"I only","correct":true},{"id":"b","text":"I and II only","correct":false,"misconception_id":"te.uses-fe-co.mc3"},{"id":"c","text":"I and III only","correct":false},{"id":"d","text":"I, II and III","correct":false}],"book_ref":"Ch.1 economic importance: 6-Iron, 7-Cobalt (printed '27-Cobalt'), pp.6-7","difficulty":4,"concept_ids":["te.uses-fe-co","phys.radioactivity-gamma","atom.isotopes"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Correct! Both uses depend on the gamma rays of cobalt-60, exposure does not make food radioactive, and not every cobalt isotope gives out gamma rays."},"b":{"why":"(II) is wrong: the rays pass through the spices and leave no radioactive substance inside them.","feedback":"Misconception: Food exposed to gamma rays becomes radioactive."},"c":{"why":"(III) is wrong: the book says cobalt-60 is important because it produces gamma rays, and not every isotope of cobalt gives out rays.","feedback":"Misconception: All isotopes of an element have the same nuclear behaviour."},"d":{"why":"(I) is fine, but being exposed is not the same as becoming radioactive (II), and isotopes do not share the same nucleus (III).","feedback":"Misconception: Mixing up exposure with contamination, and isotopes with identical atoms."}},"explanation":"(I) Correct: the book (p.7) says cobalt-60 produces gamma rays with high penetrating power, used in food preserving and to detect cracks and welding connections. (II) Wrong: gamma rays pass through the spices and kill microbes; no radioactive substance is added, so the spices do not become radioactive. (III) Wrong: isotopes have the same number of protons but different numbers of neutrons, so their nuclei differ. Cobalt-59 is the stable isotope of cobalt and gives out no gamma rays; cobalt-60 has an unstable nucleus. Answer: I only."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الاستخدامين معتمدين على الـ gamma rays بتاعة الـ cobalt-60، والتعرّض ليها مش بيخلّي الأكل radioactive، ومش أي isotope للـ cobalt بيطلّع gamma rays."},"b":{"why":"(II) غلط: الأشعة بتعدّي من التوابل ومش بتسيب مادة radioactive جواها، فالتوابل مش بتبقى radioactive.","feedback":"الفكرة الغلط: إن الأكل اللي بيتعرّض للـ gamma rays بيبقى radioactive."},"c":{"why":"(III) غلط: الكتاب بيقول إن الـ cobalt-60 مهم عشان بيطلّع gamma rays، ومش أي isotope للـ cobalt بيطلّع أشعة.","feedback":"الفكرة الغلط: إن كل الـ isotopes بتاعة العنصر الواحد ليها نفس السلوك النووي."},"d":{"why":"(I) تمام، لكن (II) و(III) غلط: التعرّض للأشعة مش زي إن الحاجة تبقى radioactive، والـ isotopes مش ليها نفس الـ nucleus.","feedback":"الفكرة الغلط: الخلط بين التعرّض للأشعة والتلوّث بمادة radioactive، وبين الـ isotopes والذرات المتطابقة."}},"explanation":"(I) صح: الكتاب (p.7) بيقول إن الـ cobalt-60 بيطلّع gamma rays ليها high penetrating power، وبنستخدمها في food preserving وفي اكتشاف الشروخ ووصلات اللحام (cracks and welding connections). (II) غلط: الـ gamma rays بتعدّي من التوابل وبتموّت الميكروبات؛ مفيش مادة radioactive بتتضاف، فالتوابل مش بتبقى radioactive. (III) غلط: الـ isotopes ليها نفس عدد الـ protons لكن عدد الـ neutrons مختلف، فالـ nuclei بتاعتهم مختلفة. الـ Cobalt-59 هو الـ isotope المستقر للـ cobalt ومش بيطلّع gamma rays، أما الـ cobalt-60 فالـ nucleus بتاعته مش مستقرة. الإجابة: I only."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":72,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-te.uses-ni-3","kind":"question","version":1,"ord":161,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-ni","concepts":[{"concept_id":"te.uses-ni","role":"primary"}],"title":"chem-s3-en.question-te.uses-ni-3","payload":{"stem":"Match each nickel material in column (A) with its use or property in column (B).","tags":["exam-style","match"],"type":"match","bloom":"remember","answer":[["l1","r1"],["l2","r2"],["l3","r3"],["l4","r4"],["l5","r5"]],"choices":[{"id":"l1","text":"Nickel-cadmium battery"},{"id":"l2","text":"Nickel-steel alloys"},{"id":"l3","text":"Nickel-chromium alloys"},{"id":"l4","text":"Nickel plating"},{"id":"l5","text":"Finely divided nickel"},{"id":"r1","text":"Can be recharged"},{"id":"r2","text":"Hard; resist rust and the effect of acids"},{"id":"r3","text":"Heating coils and electric furnaces"},{"id":"r4","text":"Protects metals from oxidation and rust; beautiful appearance"},{"id":"r5","text":"Catalyst in the hydrogenation of oils"}],"book_ref":"Ch.1 economic importance: 8-Nickel, p.7","difficulty":2,"concept_ids":["te.uses-ni"],"est_seconds":75},"layer":{"choices":{"l1":{"why":"The book's nickel-cadmium battery is the one that can be recharged."},"l2":{"why":"Nickel forms with steel alloys that are hard and resist rust and the effect of acids."},"l3":{"why":"Nickel-chromium alloys resist corrosion at high temperature, so they are used in heating coils and electric furnaces."},"l4":{"why":"Nickel plating protects other metals from oxidation and rust and gives them a beautiful appearance."},"l5":{"why":"Finely divided nickel is used as a catalyst in the hydrogenation of oils."},"r1":{"why":"Being rechargeable is the property the book gives for the nickel-cadmium battery."},"r2":{"why":"Hard and resistant to rust and acids describes nickel-steel alloys."},"r3":{"why":"Heating coils and electric furnaces need resistance to corrosion at high temperature: nickel-chromium alloys."},"r4":{"why":"Protecting metals from oxidation and rust while giving a beautiful appearance is what nickel plating does."},"r5":{"why":"The catalyst in the hydrogenation of oils is finely divided nickel."}},"explanation":"Book (p.7): the nickel-cadmium battery can be recharged; nickel-steel alloys are hard and resist rust and the effect of acids; nickel-chromium alloys are used in heating coils and electric furnaces because they resist corrosion at high temperature; nickel plating protects other metals from oxidation and rust and gives them a beautiful appearance; finely divided nickel is a catalyst in the hydrogenation of oils. Common confusion: nickel-steel (hard, resists acids) with nickel-chromium (resists corrosion at high temperature, for heating)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"l1":{"why":"الـ nickel-cadmium battery اللي في الكتاب هي اللي ممكن تتشحن تاني."},"l2":{"why":"الـ nickel بيعمل مع الـ steel alloys جامدة (hard) وبتقاوم الـ rust وتأثير الـ acids."},"l3":{"why":"الـ nickel-chromium alloys بتقاوم الـ corrosion في درجة الحرارة العالية، فبتتستخدم في الـ heating coils والـ electric furnaces."},"l4":{"why":"الـ nickel plating بيحمي الـ metals التانية من الـ oxidation والـ rust وبيدّيها شكل جميل."},"l5":{"why":"الـ finely divided nickel بيتستخدم catalyst في الـ hydrogenation of oils."},"r1":{"why":"إنها تتشحن تاني دي الخاصية اللي الكتاب بيدّيها للـ nickel-cadmium battery."},"r2":{"why":"جامدة (hard) وبتقاوم الـ rust والـ acids: ده وصف الـ nickel-steel alloys."},"r3":{"why":"الـ heating coils والـ electric furnaces محتاجين مقاومة للـ corrosion في درجة الحرارة العالية: الـ nickel-chromium alloys."},"r4":{"why":"حماية الـ metals من الـ oxidation والـ rust مع شكل جميل: ده شغل الـ nickel plating."},"r5":{"why":"الـ catalyst بتاع الـ hydrogenation of oils هو الـ finely divided nickel."}},"explanation":"الكتاب (p.7): الـ nickel-cadmium battery ممكن تتشحن تاني؛ الـ nickel-steel alloys جامدة (hard) وبتقاوم الـ rust وتأثير الـ acids؛ الـ nickel-chromium alloys بتتستخدم في الـ heating coils والـ electric furnaces عشان بتقاوم الـ corrosion في درجة الحرارة العالية؛ الـ nickel plating بيحمي الـ metals التانية من الـ oxidation والـ rust وبيدّيها شكل جميل؛ والـ finely divided nickel بيبقى catalyst في الـ hydrogenation of oils. لخبطة بتتكرر: إنك تخلط الـ nickel-steel (hard، وبيقاوم الـ acids) بالـ nickel-chromium (بيقاوم الـ corrosion في درجة الحرارة العالية، للتسخين)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":73,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-cu-zn-3","kind":"question","version":2,"ord":162,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.uses-cu-zn","concepts":[{"concept_id":"te.uses-cu-zn","role":"primary"}],"title":"chem-s3-en.question-te.uses-cu-zn-3","payload":{"stem":"Match each copper or zinc material in column (A) with its use or name in column (B).","tags":["exam-style","match"],"type":"match","bloom":"remember","answer":[["l1","r1"],["l2","r2"],["l3","r3"],["l4","r4"],["l5","r5"]],"choices":[{"id":"l1","text":"Copper (II) sulphate ($CuSO_4$)"},{"id":"l2","text":"Fehling solution"},{"id":"l3","text":"Zinc oxide (ZnO)"},{"id":"l4","text":"Zinc sulphide (ZnS)"},{"id":"l5","text":"Copper-tin alloy"},{"id":"r1","text":"Insecticide, fungicide and water purification"},{"id":"r2","text":"Detecting glucose"},{"id":"r3","text":"Paints, rubber and cosmetics"},{"id":"r4","text":"Illuminating paints and X-ray screens"},{"id":"r5","text":"Bronze"}],"book_ref":"Ch.1 economic importance: 9-Copper, 10-Zinc, pp.7-8","difficulty":3,"concept_ids":["te.uses-cu-zn"],"est_seconds":75},"layer":{"choices":{"l1":{"why":"Copper (II) sulphate is used as an insecticide and fungicide in the purification of water (book p.7)."},"l2":{"why":"Fehling solution, one of the copper compounds, is used to detect glucose: its blue colour changes to orange."},"l3":{"why":"Zinc oxide is used in the manufacture of paints, rubber and cosmetics (book p.8)."},"l4":{"why":"Zinc sulphide is used in the manufacture of illuminating paints and X-ray screens (book p.8)."},"l5":{"why":"Copper-tin alloys are known as bronze (book p.7); bronze has tin, not zinc."},"r1":{"why":"This is the use of copper (II) sulphate, not of Fehling solution."},"r2":{"why":"Glucose is detected with Fehling solution, a copper compound whose blue colour changes to orange."},"r3":{"why":"Paints, rubber and cosmetics use zinc oxide; the sulphide goes into illuminating paints instead."},"r4":{"why":"Illuminating paints and X-ray screens use zinc sulphide, the one that glows."},"r5":{"why":"Bronze is the name of the copper-tin alloys."}},"explanation":"Book (pp.7-8): copper (II) sulphate → insecticide and fungicide, and in the purification of water; Fehling solution (one of the copper compounds) → detecting glucose (its colour changes from blue to orange); zinc oxide → paints, rubber and cosmetics; zinc sulphide → illuminating paints and X-ray screens; copper-tin alloys → bronze. Common confusions: bronze is copper + tin (not zinc); $CuSO_4$ is not the glucose test, Fehling solution is; ZnO and ZnS are easy to swap: the sulphide is the one that glows (illuminating paints, X-ray screens)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"l1":{"why":"الـ copper (II) sulphate بيتستخدم insecticide و fungicide في تنقية المية (الكتاب ص 7)."},"l2":{"why":"الـ Fehling solution، واحد من compounds الـ copper، بيكشف الـ glucose: لونه الأزرق بيتغيّر لبرتقاني."},"l3":{"why":"الـ zinc oxide بيدخل في صناعة الدهانات والمطاط ومستحضرات التجميل (الكتاب ص 8)."},"l4":{"why":"الـ zinc sulphide بيدخل في صناعة الدهانات المضيئة وشاشات الـ X-ray (الكتاب ص 8)."},"l5":{"why":"الـ alloys اللي من copper و tin اسمها bronze (الكتاب ص 7)؛ الـ bronze فيه tin، مش zinc."},"r1":{"why":"ده استخدام الـ copper (II) sulphate، مش الـ Fehling solution."},"r2":{"why":"الـ glucose بيتكشف بالـ Fehling solution، وده compound من compounds الـ copper لونه الأزرق بيتغيّر لبرتقاني."},"r3":{"why":"الدهانات والمطاط ومستحضرات التجميل بتستخدم الـ zinc oxide؛ أما الـ sulphide فبيروح للدهانات المضيئة."},"r4":{"why":"الدهانات المضيئة وشاشات الـ X-ray بتستخدم الـ zinc sulphide، اللي بينوّر."},"r5":{"why":"الـ bronze هو اسم الـ alloys اللي من copper و tin."}},"explanation":"الكتاب (ص 7-8): الـ copper (II) sulphate ← insecticide و fungicide، وكمان في تنقية المية؛ الـ Fehling solution (واحد من compounds الـ copper) ← كشف الـ glucose (لونه بيتغيّر من الأزرق للبرتقاني)؛ الـ zinc oxide ← الدهانات والمطاط ومستحضرات التجميل؛ الـ zinc sulphide ← الدهانات المضيئة وشاشات الـ X-ray؛ الـ alloys اللي من copper و tin ← الـ bronze. حاجات بتتلخبط كتير: الـ bronze هو copper + tin (مش zinc)؛ الـ $CuSO_4$ مش هو test الـ glucose، الـ Fehling solution هو اللي بيكشفه؛ والـ ZnO والـ ZnS سهل تبدّلهم: الـ sulphide هو اللي بينوّر (الدهانات المضيئة وشاشات الـ X-ray)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":74,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.chromium-oxide-layer-4","kind":"question","version":2,"catalog_version":1,"ord":163,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.chromium-oxide-layer","concepts":[{"concept_id":"te.chromium-oxide-layer","role":"primary"},{"concept_id":"chem.rusting-corrosion","role":"secondary"}],"title":"chem-s3-en.question-te.chromium-oxide-layer-4","payload":{"stem":"Two metal sheets, X and Y, with the same surface area, are left in moist air. The oxide layer on X stays attached. The layer on Y cracks and flakes off; the flakes are collected and weighed with the sheet. The graph shows the total gain in mass of each sheet since week 0 (oxygen joining the metal).\nWhich conclusion is correct?","tags":["exam-style","compare","data","graph","new-case"],"type":"mcq","bloom":"analyze","figure":{"root":"c","elements":{"c":{"type":"Chart","props":{"kind":"line","unit":"mg","series":[{"name":"Sheet X","points":[{"x":0,"y":0},{"x":1,"y":4},{"x":2,"y":5},{"x":3,"y":5},{"x":4,"y":5},{"x":5,"y":5},{"x":6,"y":5},{"x":7,"y":5},{"x":8,"y":5}]},{"name":"Sheet Y","points":[{"x":0,"y":0},{"x":1,"y":3},{"x":2,"y":6},{"x":3,"y":9},{"x":4,"y":12},{"x":5,"y":15},{"x":6,"y":18},{"x":7,"y":21},{"x":8,"y":24}]}],"caption":"Total gain in mass of two metal sheets in moist air, flakes included (data for illustration)","x_label":"Time (weeks)","y_label":"Total gain in mass since week 0"},"children":[]}}},"choices":[{"id":"a","text":"X is like chromium: its nonporous oxide layer stops further reaction","correct":true},{"id":"b","text":"X is a less active metal than Y, because its mass stopped rising","correct":false},{"id":"c","text":"Y is like chromium, because it keeps reacting with oxygen","correct":false},{"id":"d","text":"Both oxide layers protect; Y's layer just works more slowly","correct":false,"misconception_id":"te.chromium-oxide-layer.mc2"}],"book_ref":"Ch.1 economic importance: 4-Chromium, p.6; form of Evaluation Q7 (give reasons), p.27; contrast with rusting of iron","difficulty":4,"concept_ids":["te.chromium-oxide-layer","chem.rusting-corrosion"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Correct! X reacted at first, then its layer sealed the surface."},"b":{"why":"In week 1, X gained 4 mg and Y only 3 mg, so X reacted faster at first: X is an active metal. Its mass stopped rising for another reason.","feedback":"Misconception: A metal that resists air is an inactive metal."},"c":{"why":"Chromium resists the effect of the atmosphere, but Y keeps reacting.","feedback":"Misconception: An active metal keeps reacting with air."},"d":{"why":"Y's total gain keeps rising by 3 mg every week, so its layer does not protect the metal.","feedback":"Misconception: Any oxide layer protects a metal."}},"explanation":"Read the graph in two parts. (1) Week 0 to week 1: X gains 4 mg, more than Y's 3 mg. So X is an active metal that reacts with oxygen. (2) From week 2 on, X's total gain stays at 5 mg. So the reaction has stopped: a protective layer covers X. Its layer stays attached, so it is nonporous. This is chromium's behaviour (book p.6). The molecular volume of its oxide is larger than that of the metal atoms. So the nonporous oxide layer prevents the continued interaction with oxygen of air. Y's total gain rises by 3 mg every week, and its layer flakes off. Its layer is porous, so fresh metal keeps meeting oxygen and moisture, like iron with rust. Common mistake: 'X stopped reacting, so X is less active.' The fast start shows X is active. The layer protects it, not low activity."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! X اتفاعل في الأول، وبعدين الطبقة بتاعته قفلت السطح."},"b":{"why":"في أسبوع 1، X كسب 4 mg و Y يدوب 3 mg، يعني X اتفاعل أسرع في الأول: X ده active metal. وكتلته وقفت تزيد لسبب تاني.","feedback":"الفكرة الغلط: إن الـ metal اللي بيقاوم الهوا يبقى inactive metal."},"c":{"why":"الـ chromium بيقاوم تأثير الهوا الجوي، لكن Y بيفضل يتفاعل.","feedback":"الفكرة الغلط: إن الـ active metal بيفضل يتفاعل مع الهوا."},"d":{"why":"الزيادة الكلية في كتلة Y بتفضل تطلع 3 mg كل أسبوع، يعني الطبقة بتاعته مش بتحمي الـ metal.","feedback":"الفكرة الغلط: إن أي oxide layer بتحمي الـ metal."}},"explanation":"اقرا الجراف على جزئين. (1) من أسبوع 0 لأسبوع 1: X كسب 4 mg، أكتر من الـ 3 mg بتوع Y. يعني X ده active metal بيتفاعل مع الـ oxygen. (2) من أسبوع 2 ورايح، الزيادة الكلية لـ X ثابتة عند 5 mg. يعني التفاعل وقف: فيه طبقة حامية مغطّية X. والطبقة دي فاضلة لازقة فيه، فهي nonporous. ده نفس سلوك الـ chromium (الكتاب ص 6): الـ molecular volume بتاع الـ oxide بتاعه أكبر من بتاع ذرات الـ metal، فالـ nonporous oxide layer بتمنع إن التفاعل مع الـ oxygen اللي في الهوا يكمّل. أما Y فالزيادة الكلية بتاعته بتطلع 3 mg كل أسبوع، والطبقة بتاعته بتتقشّر. طبقته porous، فالـ metal الجديد بيفضل يقابل الـ oxygen والرطوبة، زي الـ iron مع الـ rust. غلطة بتتكرر: «X وقف تفاعل، يبقى X أقل نشاطًا». البداية السريعة بتوضّح إن X نشيط. اللي بيحميه هو الطبقة، مش إن نشاطه قليل."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":75,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.first-series-elements-4","kind":"question","version":1,"ord":164,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.first-series-elements","concepts":[{"concept_id":"te.first-series-elements","role":"primary"}],"title":"chem-s3-en.question-te.first-series-elements-4","payload":{"stem":"Arrange the following elements as they appear in the first transition series, from left to right: nickel (Ni), titanium (Ti), copper (Cu), manganese (Mn), vanadium (V).","tags":["exam-style","arrange","unit-review"],"type":"order","bloom":"remember","answer":["ti","v","mn","ni","cu"],"choices":[{"id":"ti","text":"titanium (Ti)"},{"id":"v","text":"vanadium (V)"},{"id":"mn","text":"manganese (Mn)"},{"id":"ni","text":"nickel (Ni)"},{"id":"cu","text":"copper (Cu)"}],"book_ref":"Ch.1 '1-The First Transition Series' list (p.5) and economic importance order (pp.5-8)","difficulty":2,"concept_ids":["te.first-series-elements"],"est_seconds":60},"layer":{"choices":{"v":{"why":"Counting on from scandium, one element at a time, vanadium's atomic number is 23."},"cu":{"why":"Copper's atomic number is 29, larger than those of Ti, V, Mn and Ni."},"mn":{"why":"Manganese's atomic number is 25, counting on from scandium."},"ni":{"why":"Nickel and copper are easy to swap: nickel is 28 and copper is 29."},"ti":{"why":"Counting on from scandium (21), titanium's atomic number is 22."}},"explanation":"The first transition series lies in the fourth period, after calcium: $_{21}$Sc, $_{22}$Ti, $_{23}$V, $_{24}$Cr, $_{25}$Mn, $_{26}$Fe, $_{27}$Co, $_{28}$Ni, $_{29}$Cu, $_{30}$Zn. So the order is Ti (22), V (23), Mn (25), Ni (28), Cu (29). Tip: the book's economic-importance section follows the same order (1-Scandium, 2-Titanium, ... 10-Zinc), so the uses you learn in this unit also help you remember the order."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"v":{"why":"بالعدّ من الـ scandium، عنصر عنصر، الـ atomic number بتاع الـ vanadium هو 23."},"cu":{"why":"الـ atomic number بتاع الـ copper هو 29، أكبر من بتوع الـ Ti والـ V والـ Mn والـ Ni."},"mn":{"why":"الـ atomic number بتاع الـ manganese هو 25، بالعدّ من الـ scandium."},"ni":{"why":"الـ nickel والـ copper سهل تبدّلهم: الـ nickel رقمه 28 والـ copper رقمه 29."},"ti":{"why":"بالعدّ من الـ scandium (21)، الـ atomic number بتاع الـ titanium هو 22."}},"explanation":"الـ first transition series موجودة في الـ fourth period، بعد الـ calcium: $_{21}$Sc, $_{22}$Ti, $_{23}$V, $_{24}$Cr, $_{25}$Mn, $_{26}$Fe, $_{27}$Co, $_{28}$Ni, $_{29}$Cu, $_{30}$Zn. يبقى الترتيب: Ti (22)، V (23)، Mn (25)، Ni (28)، Cu (29). نصيحة: الجزء بتاع الأهمية الاقتصادية في الكتاب ماشي بنفس الترتيب (1-Scandium، 2-Titanium، ... 10-Zinc)، فالاستخدامات اللي هتذاكرها في الوحدة دي هتساعدك برضه تفتكر الترتيب."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":61,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series","section_title":"The First Transition Series","section_path":["Transition Elements","The First Transition Series"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.d-block-groups-4","kind":"question","version":1,"ord":165,"group_id":"chem-s3-en.ch1.practice.te-uses","primary_concept_id":"te.d-block-groups","concepts":[{"concept_id":"te.d-block-groups","role":"primary"}],"title":"chem-s3-en.question-te.d-block-groups-4","payload":{"stem":"Choose the correct answer: Zinc ($_{30}$Zn), the last element of the first transition series, belongs to group ...","tags":["exam-style","choose","unit-review"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"IIB (12)","correct":true},{"id":"b","text":"IIA (2)","correct":false},{"id":"c","text":"IB (11)","correct":false},{"id":"d","text":"VIII (8, 9, 10)","correct":false}],"book_ref":"Ch.1 'The Main transition elements (elements of d-block)' p.3","difficulty":2,"concept_ids":["te.d-block-groups"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Correct! Zinc is in the last column of the d-block."},"b":{"why":"Zinc's outer level is $4s^2$, like calcium's, but its series filled the 3d sublevel, so zinc is a d-block element, not in group IIA.","feedback":"Misconception: Two outer s electrons put zinc in group IIA."},"c":{"why":"Group IB holds copper, silver and gold; zinc is not in copper's column but in the next column of the d-block.","feedback":"Misconception: Zinc is in copper's group."},"d":{"why":"In this period, group VIII holds iron, cobalt and nickel; copper (IB) and then zinc come after nickel.","feedback":"Misconception: The last transition element is in group VIII."}},"explanation":"The d-block groups, from left to right: IIIB, IVB, VB, VIB, VIIB, VIII (three columns: 8, 9, 10), IB (11), IIB (12). Zinc ($4s^2\\,3d^{10}$) is in the last column of the d-block, group IIB (12), with cadmium and mercury. Copper is in IB. Zinc is not in group IIA: although it has $4s^2$, the electrons of its series filled the 3d sublevel, so it is a d-block element."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ zinc في آخر column في الـ d-block."},"b":{"why":"المستوى الخارجي للـ zinc هو $4s^2$، زي الـ calcium، لكن السلسلة بتاعته ملت الـ 3d sublevel، فالـ zinc عنصر d-block، مش في الـ group IIA.","feedback":"الفكرة الغلط: إن الـ 2 electrons اللي في الـ s الخارجي بيحطوا الـ zinc في الـ group IIA."},"c":{"why":"الـ group IB فيه الـ copper والـ silver والـ gold؛ الـ zinc مش في column الـ copper، ده في الـ column اللي بعده في الـ d-block.","feedback":"الفكرة الغلط: إن الـ zinc في نفس group الـ copper."},"d":{"why":"في الـ period ده، الـ group VIII فيه الـ iron والـ cobalt والـ nickel؛ وبعد الـ nickel ييجي الـ copper (IB) وبعدين الـ zinc.","feedback":"الفكرة الغلط: إن آخر transition element بيبقى في الـ group VIII."}},"explanation":"الـ d-block groups من الشمال لليمين: IIIB، IVB، VB، VIB، VIIB، VIII (تلات columns: 8، 9، 10)، IB (11)، IIB (12). الـ zinc ($4s^2\\,3d^{10}$) في آخر column في الـ d-block، الـ group IIB (12)، مع الـ cadmium والـ mercury. والـ copper في الـ IB. والـ zinc مش في الـ group IIA: صحيح عنده $4s^2$، لكن الـ electrons في السلسلة بتاعته ملت الـ 3d sublevel، فهو d-block element."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":62,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":3,"page_to":3,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-atom.hund-rule-1","kind":"question","version":1,"ord":196,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"atom.hund-rule","concepts":[{"concept_id":"atom.hund-rule","role":"primary"}],"title":"chem-s3-en.question-atom.hund-rule-1","payload":{"stem":"A d sublevel contains 6 electrons ($d^6$). Which orbital diagram shows the correct arrangement of these electrons in the five d orbitals?","tags":["diagnostic","orbital-boxes"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"[↑↓] [↑] [↑] [↑] [↑]","correct":true},{"id":"b","text":"[↑↓] [↑↓] [↑↓] [  ] [  ]","correct":false},{"id":"c","text":"[↑↓] [↑] [↓] [↑] [↓]","correct":false},{"id":"d","text":"[↑↑] [↑] [↑] [↑] [↑]","correct":false}],"difficulty":2,"concept_ids":["atom.hund-rule"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! The first five electrons go one into each orbital with the same spin, and only the sixth one pairs up. That leaves 4 unpaired electrons."},"b":{"why":"This diagram fills each orbital completely before moving to the next one, while two orbitals are still empty. Electrons are all negative, so they repel each other: by Hund's rule they occupy the empty orbitals one by one before any pairing starts.","feedback":"Misconception: Electrons pair up in the first orbital before the other orbitals of the same sublevel are filled."},"c":{"why":"The number of electrons in each box is right, but the spins are not: by Hund's rule, the electrons that occupy orbitals singly all have parallel spins, not alternating ones.","feedback":"Misconception: Singly occupied orbitals must have alternating (opposite) spins."},"d":{"why":"The electrons are spread over the boxes correctly, but the orbital with two electrons shows them with the same spin. By the Pauli exclusion principle, an orbital holds two electrons at most, with opposite spins.","feedback":"Misconception: Two electrons in the same orbital can have the same spin (Pauli exclusion principle ignored)."}},"explanation":"Hund's rule: inside one sublevel, electrons enter the orbitals one by one first (a single electron in each orbital, all with parallel spins). Pairing starts only after every orbital has one electron, and the second electron in an orbital has the opposite spin (Pauli exclusion principle). For $d^6$: electrons 1-5 go ↑ into the five orbitals, and electron 6 goes ↓ into the first orbital. Result: [↑↓] [↑] [↑] [↑] [↑], so 4 unpaired electrons. You will need exactly this drawing for the 3d sublevel of iron ($3d^6$)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! أول خمس electrons بيدخلوا كل واحد في orbital بنفس الـ spin، والسادس تحديدًا هو اللي بيعمل زوج. فيفضل 4 unpaired electrons."},"b":{"why":"الرسمة دي بتملا كل orbital على الآخر قبل ما تروح للي بعده، مع إن لسه فيه اتنين orbitals فاضيين. والـ electrons كلها negative فبتتنافر مع بعض: وحسب الـ Hund's rule بتدخل الـ orbitals الفاضية واحد واحد قبل ما أي أزواج تبتدي.","feedback":"الفكرة الغلط: إن الـ electrons بتعمل أزواج في أول orbital قبل ما باقي الـ orbitals في نفس الـ sublevel تتملي."},"c":{"why":"عدد الـ electrons في كل مربع صح، لكن الـ spins لأ: حسب الـ Hund's rule، الـ electrons اللي داخلة الـ orbitals فرادى بيبقى ليها parallel spins، مش بالتبادل.","feedback":"الفكرة الغلط: إن الـ orbitals اللي فيها electron واحد لازم الـ spins بتاعتها تبقى بالتبادل (opposite)."},"d":{"why":"الـ electrons متوزعة على المربعات صح، لكن الـ orbital اللي فيه اتنين electrons راسمهم بنفس الـ spin. وحسب الـ Pauli exclusion principle، الـ orbital بياخد اتنين electrons بالكتير، بـ spins opposite.","feedback":"الفكرة الغلط: إن اتنين electrons في نفس الـ orbital ممكن يبقى ليهم نفس الـ spin (تجاهل الـ Pauli exclusion principle)."}},"explanation":"الـ Hund's rule: جوه الـ sublevel الواحد، الـ electrons بتدخل الـ orbitals واحد واحد الأول (electron واحد في كل orbital، وكلهم بـ parallel spins). الأزواج مش بتبتدي غير بعد ما كل orbital ياخد electron واحد، والـ electron التاني في الـ orbital بيبقى الـ spin بتاعه opposite (الـ Pauli exclusion principle). في الـ $d^6$: الـ electrons من 1 لـ 5 بيدخلوا ↑ في الخمس orbitals، والـ electron رقم 6 بيدخل ↓ في أول orbital. النتيجة: [↑↓] [↑] [↑] [↑] [↑]، يعني 4 unpaired electrons. وهتحتاج الرسمة دي بالظبط في الـ 3d sublevel بتاع الـ iron ($3d^6$)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":23,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic.ex-a","section_title":"Paramagnetic or diamagnetic","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties","Paramagnetic or diamagnetic"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-atom.hund-rule-2","kind":"question","version":1,"ord":197,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"atom.hund-rule","concepts":[{"concept_id":"atom.hund-rule","role":"primary"}],"title":"chem-s3-en.question-atom.hund-rule-2","payload":{"stem":"The electrons of a $d^8$ sublevel are distributed in its five orbitals according to Hund's rule. How many unpaired electrons are there?","tags":["diagnostic","unpaired-electrons"],"type":"numeric","bloom":"apply","answer":{"unit":"electrons","value":2,"tolerance":0},"difficulty":2,"concept_ids":["atom.hund-rule"],"est_seconds":40},"layer":{"explanation":"Step 1: the five d orbitals take the first 5 electrons one by one, all with the same spin: [↑] [↑] [↑] [↑] [↑]. Step 2: electrons 6, 7 and 8 pair up in the first three orbitals: [↑↓] [↑↓] [↑↓] [↑] [↑]. So there are 2 unpaired electrons. Common wrong answers: 0 (pairing from the start, which draws 4 pairs and an empty box: this ignores Hund's rule); 3 (counting the electrons after half-filling, $8-5=3$, as unpaired, when those are exactly the ones that paired up); 8 (thinking every d electron is unpaired). Quick check: after $d^5$, every extra electron lowers the number of unpaired electrons by one, so $d^8$ has $10-8=2$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"خطوة 1: الـ 5 d orbitals بياخدوا أول 5 electrons واحد واحد، وكلهم بنفس الـ spin: [↑] [↑] [↑] [↑] [↑]. خطوة 2: الـ electrons رقم 6 و7 و8 بيعملوا أزواج في أول تلات orbitals: [↑↓] [↑↓] [↑↓] [↑] [↑]. يعني فيه 2 unpaired electrons. إجابات غلط بتتكرر: 0 (إنك تعمل أزواج من الأول، فترسم 4 أزواج ومربع فاضي: كده إنت متجاهل الـ Hund's rule)؛ 3 (إنك تعد الـ electrons اللي بعد نص الملء، $8-5=3$، على إنها unpaired، مع إنها هي بالظبط اللي عملت أزواج)؛ 8 (إنك تفتكر إن كل الـ d electrons unpaired). اختبار سريع: بعد الـ $d^5$، كل electron زيادة بيقلل عدد الـ unpaired electrons واحد، فالـ $d^8$ فيه $10-8=2$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":24,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic.ex-a","section_title":"Paramagnetic or diamagnetic","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties","Paramagnetic or diamagnetic"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-atom.hund-rule-3","kind":"question","version":1,"ord":198,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"atom.hund-rule","concepts":[{"concept_id":"atom.hund-rule","role":"primary"}],"title":"chem-s3-en.question-atom.hund-rule-3","payload":{"stem":"In a p or d sublevel, why do electrons occupy the orbitals singly first before they start pairing?","tags":["diagnostic","reason"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Because they repel each other less when they are spread out, so the energy is lower","correct":true},{"id":"b","text":"Because one orbital can hold only one electron","correct":false},{"id":"c","text":"Because each orbital in the sublevel is higher in energy than the one before it","correct":false}],"difficulty":2,"concept_ids":["atom.hund-rule"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Exactly. All electrons are negative, so when each one has its own orbital the repulsion is smaller and the atom is more stable."},"b":{"why":"An orbital holds up to 2 electrons with opposite spins, which is how a d sublevel holds 10 electrons in 5 orbitals. So the reason they wait before pairing lies elsewhere.","feedback":"Misconception: An orbital can hold only one electron (Pauli exclusion principle misremembered)."},"c":{"why":"The orbitals of the same sublevel all have the same energy, so none of them is lower than the others. The reason lies in the charge of the electrons: all of them are negative.","feedback":"Misconception: Orbitals of the same sublevel have different energies and fill in order of energy."}},"explanation":"The orbitals of one sublevel have equal energy. All electrons are negatively charged, so they repel each other. The arrangement with the lowest energy (the most stable one) is when the electrons stay unpaired, one in each orbital, with parallel spins. Pairing happens only after every orbital has one electron, and then the second electron enters with the opposite spin. This is Hund's rule, and it is why the 3d sublevel in the first transition series fills singly up to manganese ($3d^5$) before pairing starts."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"بالظبط. الـ electrons كلها negative، فلما كل واحد ياخد orbital لوحده التنافر بيقل والذرة بتبقى أكثر استقرارًا."},"b":{"why":"لو الكلام ده صح، الـ d sublevel ماكانش هيقدر يشيل 10 electrons في 5 orbitals بس. الـ orbital بيشيل لحد 2 electrons بـ spins متعاكسة، فالسبب مش السعة.","feedback":"الفكرة الغلط: إن الـ orbital يشيل electron واحد بس (لخبطة في تذكّر الـ Pauli exclusion principle)."},"c":{"why":"الـ orbitals اللي في نفس الـ sublevel كلها ليها نفس الـ energy، فمفيش واحد فيهم أعلى من التانيين. السبب مرتبط بالـ negative charge بتاعة الـ electrons.","feedback":"الفكرة الغلط: إن orbitals نفس الـ sublevel ليها energies مختلفة وبتتملي بترتيب الـ energy."}},"explanation":"الـ orbitals بتوع الـ sublevel الواحد ليهم energy متساوية. والـ electrons كلها negatively charged، فبتتنافر مع بعض. الترتيب اللي ليه أقل energy (يعني الأكثر استقرارًا) هو إن الـ electrons تفضل unpaired، كل واحد في orbital، والـ spins متوازية. الأزواج مابتبدأش غير بعد ما كل orbital ياخد electron واحد، ووقتها الـ electron التاني بيدخل بـ spin عكسي. ده الـ Hund's rule، وعشان كده الـ 3d sublevel في الـ first transition series بيتملي فرادى لحد الـ manganese ($3d^5$) قبل ما الأزواج تبدأ."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":25,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.ions-1","kind":"question","version":1,"ord":199,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"chem.ions","concepts":[{"concept_id":"chem.ions","role":"primary"}],"title":"chem-s3-en.question-chem.ions-1","payload":{"stem":"How many electrons does the ion $\\ce{_{24}Cr^{3+}}$ have?","tags":["diagnostic","book_ref:Ch.1 point 3, p.9 (ions of the first series)"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"21","correct":true},{"id":"b","text":"27","correct":false},{"id":"c","text":"24","correct":false},{"id":"d","text":"3","correct":false}],"book_ref":"Ch.1 point 3, p.9 (ions of the first series)","difficulty":1,"concept_ids":["chem.ions"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Right: 24 − 3 = 21 electrons, and still 24 protons."},"b":{"why":"A 3+ charge means electrons left the atom, so the electron count goes down, not up.","feedback":"Misconception: A positive charge means electrons were gained."},"c":{"why":"24 is the neutral atom. The 3+ shows that the atom lost 3 electrons.","feedback":"Misconception: The ion has the same number of electrons as the atom."},"d":{"why":"3 is the charge, not the electron count. Start from Z = 24.","feedback":"Misconception: The charge equals the number of electrons in the ion."}},"explanation":"Chromium has Z = 24, so its atom has 24 protons and 24 electrons. The 3+ charge means the atom lost 3 electrons. Electrons in a cation = Z − charge = 24 − 3 = 21. The protons stay 24, so it is still chromium. Most likely wrong answer: 27, from adding the charge. A positive charge means electrons were lost, not gained."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: 24 − 3 = 21 electrons، والـ protons لسه 24."},"b":{"why":"الـ 3+ charge معناها إن فيه electrons خرجت من الذرة، فعدد الـ electrons بيقل، مش بيزيد.","feedback":"الفكرة الغلط: إن الـ positive charge معناها إن الذرة كسبت electrons."},"c":{"why":"24 دي الذرة المتعادلة. الـ 3+ معناها إن الذرة فقدت 3 electrons.","feedback":"الفكرة الغلط: إن الـ ion فيه نفس عدد الـ electrons اللي في الذرة."},"d":{"why":"3 دي الـ charge، مش عدد الـ electrons. ابدأ من Z = 24.","feedback":"الفكرة الغلط: إن الـ charge بتساوي عدد الـ electrons اللي في الـ ion."}},"explanation":"الـ chromium عنده Z = 24، يعني الذرة فيها 24 protons و 24 electrons. الـ 3+ charge معناها إن الذرة فقدت 3 electrons. عدد الـ electrons في الـ cation = Z − charge = 24 − 3 = 21. والـ protons فاضلة 24، فهو لسه chromium. أشهر غلطة: 27، لما تجمع الـ charge بدل ما تطرحها. الـ positive charge معناها إن electrons اتفقدت، مش اتكسبت."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":26,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.ions-2","kind":"question","version":1,"ord":200,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"chem.ions","concepts":[{"concept_id":"chem.ions","role":"primary"}],"title":"chem-s3-en.question-chem.ions-2","payload":{"stem":"Compare the nickel atom ($_{28}$Ni) with the ion $\\ce{Ni^{2+}}$. Which statement is correct?","tags":["diagnostic","book_ref:Ch.1 point 3, p.9 (ions of the first series)"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Same number of protons; $\\ce{Ni^{2+}}$ has two fewer electrons","correct":true},{"id":"b","text":"Same number of protons; $\\ce{Ni^{2+}}$ has two more electrons","correct":false},{"id":"c","text":"$\\ce{Ni^{2+}}$ has two fewer protons and the same electrons","correct":false},{"id":"d","text":"$\\ce{Ni^{2+}}$ has two more protons and the same electrons","correct":false}],"book_ref":"Ch.1 point 3, p.9 (ions of the first series)","difficulty":1,"concept_ids":["chem.ions"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Right: only electrons leave. The 28 protons keep it nickel."},"b":{"why":"Electrons are negative. Gaining two of them would make the particle negative, not positive.","feedback":"Misconception: A positive ion forms by gaining electrons."},"c":{"why":"If the protons changed, it would no longer be nickel. Only electrons move when an ion forms.","feedback":"Misconception: Protons are lost when a positive ion forms."},"d":{"why":"Protons fix the element. An atom loses or gains electrons, not protons, to become an ion.","feedback":"Misconception: The positive charge comes from added protons."}},"explanation":"When an ion forms, only electrons move. The protons stay the same, so it is still nickel. The Ni atom has 28 protons and 28 electrons. $\\ce{Ni^{2+}}$ lost 2 electrons, so it has 28 protons and 26 electrons. Two positive charges are left over, which gives the 2+ charge."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: اللي بيخرج هو الـ electrons تحديدًا. والـ 28 protons بيفضلوا مخلّيينه nickel."},"b":{"why":"الـ electrons شايلة negative charge. لو الذرة كسبت 2 منهم، هتبقى negative، مش positive.","feedback":"الفكرة الغلط: إن الـ positive ion بيتكوّن لما الذرة تكسب electrons."},"c":{"why":"لو الـ protons اتغيرت، الذرة مش هتفضل nickel. اللي بيتحرك لما الـ ion يتكوّن هو الـ electrons.","feedback":"الفكرة الغلط: إن الـ protons بتضيع لما الـ positive ion يتكوّن."},"d":{"why":"الـ protons هي اللي بتحدد العنصر، فمابتتغيرش. الذرة بتبقى ion لما تفقد أو تكسب electrons.","feedback":"الفكرة الغلط: إن الـ positive charge جاية من protons اتضافت."}},"explanation":"لما الـ ion يتكوّن، اللي بيتحرك هو الـ electrons تحديدًا. الـ protons بتفضل زي ما هي، فهو لسه nickel. ذرة الـ Ni فيها 28 protons و 28 electrons. الـ $\\ce{Ni^{2+}}$ فقد 2 electrons، فبقى فيه 28 protons و 26 electrons. فاضل 2 positive charges زيادة، ودول اللي بيدّوا الـ 2+ charge."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":27,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic.ex-a","section_title":"Paramagnetic or diamagnetic","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties","Paramagnetic or diamagnetic"],"relation":"based_on"}]},{"id":"chem-s3-en.question-pt.oxidation-number-1","kind":"question","version":1,"ord":201,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"pt.oxidation-number","concepts":[{"concept_id":"pt.oxidation-number","role":"primary"}],"title":"chem-s3-en.question-pt.oxidation-number-1","payload":{"stem":"What is the oxidation state of nickel in $\\ce{Ni2O3}$? (O = −2)","tags":["diagnostic","book_ref:Ch.1 oxidation-states table, p.8 (Ni₂O₃)"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"+3","correct":true},{"id":"b","text":"+6","correct":false},{"id":"c","text":"+2","correct":false},{"id":"d","text":"−3","correct":false}],"book_ref":"Ch.1 oxidation-states table, p.8 (Ni₂O₃)","difficulty":2,"concept_ids":["pt.oxidation-number"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: 2x + 3(−2) = 0, so x = +3. This is nickel (III) oxide."},"b":{"why":"+6 is the total for all the nickel, and two Ni atoms share it.","feedback":"Misconception: The whole positive total belongs to one metal atom."},"c":{"why":"The subscript 2 counts Ni atoms; it is not the oxidation state. The oxidation states in the compound add up to zero.","feedback":"Misconception: The subscript of the metal is its oxidation state."},"d":{"why":"Three O atoms give a negative total (−6), so nickel must be positive to cancel it.","feedback":"Misconception: Sign error: the metal takes the same sign as oxygen."}},"explanation":"Call nickel x. Two Ni atoms give 2x. Three O atoms give 3 × (−2) = −6. In a compound, the oxidation states add up to zero: 2x − 6 = 0. So 2x = +6 and x = +3. The name is nickel (III) oxide. Most likely wrong answer: +6, giving the whole total to one Ni atom."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: 2x + 3(−2) = 0، يبقى x = +3. وده اسمه nickel (III) oxide."},"b":{"why":"+6 ده المجموع بتاع الـ nickel بالكامل، واتنين Ni atoms بيتقسموه.","feedback":"الفكرة الغلط: إن المجموع الموجب بالكامل بيروح لذرة metal واحدة."},"c":{"why":"الـ subscript 2 بيعدّ الـ Ni atoms، مش هو الـ oxidation state. ومجموع الـ oxidation states في الـ compound بيساوي صفر.","feedback":"الفكرة الغلط: إن الـ subscript بتاع الـ metal هو الـ oxidation state بتاعه."},"d":{"why":"الـ 3 O atoms بيدّوا مجموع سالب (−6)، فالـ nickel لازم يبقى positive عشان يلغيه.","feedback":"الفكرة الغلط: إن الـ metal بياخد نفس إشارة الـ oxygen (غلطة في الإشارة)."}},"explanation":"سمّي الـ nickel x. الـ 2 Ni atoms بيدّوا 2x، والـ 3 O atoms بيدّوا 3 × (−2) = −6. في الـ compound، مجموع الـ oxidation states بيساوي صفر: 2x − 6 = 0. يبقى 2x = +6، و x = +3. والاسم nickel (III) oxide. أشهر غلطة: +6، لما تدّي المجموع بالكامل لـ Ni atom واحدة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":28,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"beyond"}]},{"id":"chem-s3-en.question-pt.oxidation-number-2","kind":"question","version":1,"ord":202,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"pt.oxidation-number","concepts":[{"concept_id":"pt.oxidation-number","role":"primary"}],"title":"chem-s3-en.question-pt.oxidation-number-2","payload":{"stem":"What is the oxidation state of chromium in $\\ce{Cr2(SO4)3}$? (The $\\ce{SO4}$ group = −2)","tags":["diagnostic","book_ref:Ch.1 oxidation-states table, p.8 (chromium +3)"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"+3","correct":true},{"id":"b","text":"+6","correct":false},{"id":"c","text":"+12","correct":false},{"id":"d","text":"+2","correct":false}],"book_ref":"Ch.1 oxidation-states table, p.8 (chromium +3)","difficulty":2,"concept_ids":["pt.oxidation-number"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: 2x + 3(−2) = 0, so x = +3. This is chromium (III) sulphate."},"b":{"why":"Three $\\ce{SO4}$ groups give −6, and the +6 that cancels it is shared by two Cr atoms.","feedback":"Misconception: The whole positive total belongs to one metal atom."},"c":{"why":"+12 comes from counting each O atom on its own. The whole $\\ce{SO4}$ group counts as −2.","feedback":"Misconception: Counting every O atom as −2 and ignoring sulphur in the sulphate group."},"d":{"why":"The 2 counts chromium atoms. All the oxidation states add up to zero: 2x − 6 = 0.","feedback":"Misconception: The subscript of the metal is its oxidation state."}},"explanation":"Call chromium x. Two Cr atoms give 2x. Three $\\ce{SO4}$ groups give 3 × (−2) = −6. The sum is zero: 2x − 6 = 0, so x = +3. The name is chromium (III) sulphate. Treat $\\ce{SO4}$ as one group with −2. Do not count its O atoms one by one."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: 2x + 3(−2) = 0، يبقى x = +3. وده اسمه chromium (III) sulphate."},"b":{"why":"تلات $\\ce{SO4}$ groups بيدّوا −6، والـ +6 اللي بتلغيها متقسمة على اتنين Cr atoms.","feedback":"الفكرة الغلط: إن المجموع الموجب بالكامل بيروح لذرة metal واحدة."},"c":{"why":"الـ +12 جاية من إنك حسبت كل O atom لوحدها. الـ $\\ce{SO4}$ group على بعضها بتتحسب بـ −2.","feedback":"الفكرة الغلط: إنك تحسب الـ O atom الواحدة بـ −2 وتتجاهل الـ sulphur اللي في الـ sulphate group."},"d":{"why":"الـ 2 بيعدّ الـ chromium atoms. ومجموع الـ oxidation states كلها بيساوي صفر: 2x − 6 = 0.","feedback":"الفكرة الغلط: إن الـ subscript بتاع الـ metal هو الـ oxidation state بتاعه."}},"explanation":"سمّي الـ chromium x. الـ 2 Cr atoms بيدّوا 2x، والـ 3 $\\ce{SO4}$ groups بيدّوا 3 × (−2) = −6. المجموع بيساوي صفر: 2x − 6 = 0، يبقى x = +3. والاسم chromium (III) sulphate. اتعامل مع الـ $\\ce{SO4}$ على إنها group واحدة قيمتها −2، وماتعدّش الـ O atoms بتوعها واحدة واحدة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":29,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"beyond"}]},{"id":"chem-s3-en.question-redox.electronic-1","kind":"question","version":1,"ord":203,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"redox.electronic","concepts":[{"concept_id":"redox.electronic","role":"primary"}],"title":"chem-s3-en.question-redox.electronic-1","payload":{"stem":"In the change $\\ce{Mn^{2+} -> Mn^{3+} + e-}$, what happens to manganese?","tags":["diagnostic","book_ref:Ch.1 worked exercise, p.9 (Mn (II) to Mn (III))"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"It is oxidized: it loses an electron, and its oxidation state increases","correct":true},{"id":"b","text":"It is reduced: it gains an electron, and its oxidation state increases","correct":false},{"id":"c","text":"It is oxidized: it loses an electron, and its oxidation state decreases","correct":false},{"id":"d","text":"Nothing is oxidized or reduced, because no oxygen takes part","correct":false,"misconception_id":"redox.electronic.mc1"}],"book_ref":"Ch.1 worked exercise, p.9 (Mn (II) to Mn (III))","difficulty":1,"concept_ids":["redox.electronic"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Right: an electron is given out, and +2 rises to +3."},"b":{"why":"The electron is on the right of the arrow, so it is given out, not taken in.","feedback":"Misconception: An electron on the product side is gained."},"c":{"why":"Losing a negative electron leaves more positive charge: +2 → +3 is an increase.","feedback":"Misconception: Losing electrons lowers the oxidation state."},"d":{"why":"Oxidation has a wider meaning than gaining oxygen: it is the loss of electrons, and here an electron is lost.","feedback":"Misconception: Oxidation always needs oxygen."}},"explanation":"Oxidation is the loss of electrons, and the oxidation state increases. Here the electron is on the right: manganese gives it out. Its oxidation state goes from +2 to +3. So manganese (II) is oxidized. No oxygen is needed for oxidation."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: فيه electron طالع، والـ +2 بقى +3."},"b":{"why":"الـ electron موجود على يمين السهم، يعني طالع مش داخل.","feedback":"الفكرة الغلط: إن الـ electron اللي على يمين السهم (ناحية النواتج) يبقى اتكسب."},"c":{"why":"لما يخسر electron وهو negative، الـ positive charge اللي بتفضل بتزيد: +2 → +3 ده طلوع.","feedback":"الفكرة الغلط: إن خسارة electrons بتقلّل الـ oxidation state."},"d":{"why":"الـ oxidation معناه أوسع من إن المادة تكسب oxygen: معناه خسارة electrons، وهنا فيه electron بيتخسر.","feedback":"الفكرة الغلط: إن الـ oxidation لازم يكون فيه oxygen دايمًا."}},"explanation":"الـ oxidation هو خسارة electrons، والـ oxidation state بيزيد معاه. هنا الـ electron موجود على اليمين، يعني الـ manganese هو اللي طلّعه، والـ oxidation state بتاعه راح من +2 لـ +3. يبقى الـ manganese (II) حصله oxidation (oxidized). والـ oxidation مش محتاج oxygen عشان يحصل."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":30,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":84,"page_to":84,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"chem-s3-en.question-redox.electronic-2","kind":"question","version":1,"ord":204,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"redox.electronic","concepts":[{"concept_id":"redox.electronic","role":"primary"}],"title":"chem-s3-en.question-redox.electronic-2","payload":{"stem":"In the reaction $\\ce{2FeCl2 + Cl2 -> 2FeCl3}$, which substance is the oxidizing agent?","tags":["diagnostic","book_ref:Ch.1 worked exercise, p.9 (iron (II) oxidized to iron (III))"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$\\ce{Cl2}$","correct":true},{"id":"b","text":"$\\ce{FeCl2}$","correct":false},{"id":"c","text":"$\\ce{FeCl3}$","correct":false},{"id":"d","text":"None, because no oxygen takes part","correct":false,"misconception_id":"redox.electronic.mc1"}],"book_ref":"Ch.1 worked exercise, p.9 (iron (II) oxidized to iron (III))","difficulty":2,"concept_ids":["redox.electronic"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: chlorine gains electrons (0 → −1), so it is reduced. That makes it the oxidizing agent."},"b":{"why":"Iron goes from +2 to +3, so it loses electrons and is oxidized. That makes $\\ce{FeCl2}$ the reducing agent; the oxidizing agent is the one reduced.","feedback":"Misconception: The oxidizing agent is the substance that is oxidized."},"c":{"why":"$\\ce{FeCl3}$ is a product, and agents are reactants.","feedback":"Misconception: A product can be the oxidizing agent."},"d":{"why":"Oxidation can happen without oxygen: here iron loses electrons and chlorine gains them.","feedback":"Misconception: Oxidation always needs oxygen."}},"explanation":"First find the oxidation states. Iron: +2 in $\\ce{FeCl2}$ → +3 in $\\ce{FeCl3}$. It loses electrons, so it is oxidized. Chlorine: 0 in $\\ce{Cl2}$ → −1 in $\\ce{FeCl3}$. It gains electrons, so it is reduced. The oxidizing agent is the substance that is itself reduced: $\\ce{Cl2}$. $\\ce{FeCl2}$ is the reducing agent."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ chlorine بيكسب electrons (0 → −1)، يبقى هو reduced. وده اللي بيخليه الـ oxidizing agent."},"b":{"why":"الـ iron بيروح من +2 لـ +3، يعني بيخسر electrons وبيبقى oxidized. ده بيخلّي الـ $\\ce{FeCl2}$ هو الـ reducing agent؛ الـ oxidizing agent هو اللي بيبقى reduced.","feedback":"الفكرة الغلط: إن الـ oxidizing agent هو المادة اللي بيحصلها oxidation."},"c":{"why":"الـ $\\ce{FeCl3}$ ده product، والـ agents بيبقوا reactants.","feedback":"الفكرة الغلط: إن الـ product ممكن يبقى هو الـ oxidizing agent."},"d":{"why":"الـ oxidation ممكن يحصل من غير oxygen: هنا الـ iron بيخسر electrons والـ chlorine بيكسبها.","feedback":"الفكرة الغلط: إن الـ oxidation لازم يكون فيه oxygen دايمًا."}},"explanation":"أول حاجة طلّع الـ oxidation states. الـ iron: +2 في الـ $\\ce{FeCl2}$ → +3 في الـ $\\ce{FeCl3}$، يعني خسر electrons، يبقى هو oxidized. الـ chlorine: 0 في الـ $\\ce{Cl2}$ → −1 في الـ $\\ce{FeCl3}$، يعني كسب electrons، يبقى هو reduced. والـ oxidizing agent هو المادة اللي نفسها بتبقى reduced: يعني الـ $\\ce{Cl2}$. أما الـ $\\ce{FeCl2}$ فهو الـ reducing agent."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":31,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"relation":"beyond"}]},{"id":"chem-s3-en.question-pt.atomic-radius-trend-1","kind":"question","version":1,"ord":205,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"pt.atomic-radius-trend","concepts":[{"concept_id":"pt.atomic-radius-trend","role":"primary"}],"title":"chem-s3-en.question-pt.atomic-radius-trend-1","payload":{"stem":"Magnesium ($_{12}$Mg) and sulphur ($_{16}$S) are both in period 3. Which statement is correct?","tags":["diagnostic","book_ref:Ch.1 general properties: atomic radius, pp.12-13 (background)"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Mg is larger, because S has more protons pulling the same outer level","correct":true},{"id":"b","text":"S is larger, because it has more electrons than Mg","correct":false},{"id":"c","text":"They are equal in size, because both use three main levels","correct":false},{"id":"d","text":"S is larger, because its outer electrons are in a higher level","correct":false}],"book_ref":"Ch.1 general properties: atomic radius, pp.12-13 (background)","difficulty":1,"concept_ids":["pt.atomic-radius-trend"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Right: same outer level, more protons in S, so a stronger pull."},"b":{"why":"S also has more protons. In the same level, the extra pull wins over the extra electrons, so S is smaller.","feedback":"Misconception: More electrons always make a bigger atom."},"c":{"why":"Same levels, yes. But S has more protons, so its nucleus pulls the outer level harder.","feedback":"Misconception: The same number of main levels means the same size."},"d":{"why":"Both atoms are in period 3, so their outer electrons are in the same main level (n = 3).","feedback":"Misconception: A higher atomic number means a higher outer level within a period."}},"explanation":"Across a period, the outer electrons stay in the same main level (n = 3). Each step adds one proton, so the nucleus pulls that level harder. So the radius decreases from Mg to S. Mg is the larger atom. More electrons do not win here; the stronger pull does."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: نفس المستوى الخارجي، والـ S فيه protons أكتر، يبقى الشدّ أقوى."},"b":{"why":"الـ S عنده كمان protons أكتر. وفي نفس المستوى، الشدّ الزيادة بيكسب الـ electrons الزيادة، فالـ S بيبقى أصغر.","feedback":"الفكرة الغلط: إن electrons أكتر دايمًا معناها ذرة أكبر."},"c":{"why":"المستويات واحدة، صح. لكن الـ S عنده protons أكتر، فالـ nucleus بتاعته بتشد المستوى الخارجي أقوى.","feedback":"الفكرة الغلط: إن نفس عدد المستويات الرئيسية معناه نفس الحجم."},"d":{"why":"الذرتين في الـ period 3، يعني الـ outer electrons بتاعتهم في نفس المستوى الرئيسي (n = 3).","feedback":"الفكرة الغلط: إن الـ atomic number الأكبر جوه الـ period معناه مستوى خارجي أعلى."}},"explanation":"لما تمشي في الـ period، الـ outer electrons بتفضل في نفس المستوى الرئيسي (n = 3). ومع كل خطوة بيتضاف proton، فالـ nucleus بتشد المستوى ده أقوى. عشان كده الـ radius بيقل من الـ Mg للـ S، والـ Mg هو الذرة الأكبر. هنا الـ electrons الزيادة مش هي اللي بتكسب؛ الشدّ الأقوى هو اللي بيكسب."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":32,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"beyond"}]},{"id":"chem-s3-en.question-pt.atomic-radius-trend-2","kind":"question","version":1,"ord":206,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"pt.atomic-radius-trend","concepts":[{"concept_id":"pt.atomic-radius-trend","role":"primary"}],"title":"chem-s3-en.question-pt.atomic-radius-trend-2","payload":{"stem":"Across a period, one proton and one electron are added at each step. Which two factors act on the atomic radius in opposite directions?","tags":["diagnostic","book_ref:Ch.1 general properties: atomic radius, pp.12-13 (two opposite factors)"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"The nucleus attracts electrons inward; electrons repel each other outward","correct":true},{"id":"b","text":"The nucleus repels electrons outward; electrons attract each other inward","correct":false},{"id":"c","text":"Neutrons attract electrons inward; protons repel electrons outward","correct":false},{"id":"d","text":"Protons repel each other inward; electrons attract each other outward","correct":false}],"book_ref":"Ch.1 general properties: atomic radius, pp.12-13 (two opposite factors)","difficulty":2,"concept_ids":["pt.atomic-radius-trend"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: the pull of the protons against the push between electrons."},"b":{"why":"Protons are positive and electrons are negative, and opposite charges attract, so the nucleus pulls the electrons in.","feedback":"Misconception: Reversing the roles of attraction and repulsion."},"c":{"why":"Neutrons have no charge. The protons in the nucleus attract the negative electrons.","feedback":"Misconception: Neutrons hold electrons; protons push them away."},"d":{"why":"All electrons are negative, and two negative charges repel, so electrons push each other apart.","feedback":"Misconception: Electrons attract one another."}},"explanation":"Two factors act at the same time. More protons attract the electrons more strongly, which decreases the radius. More electrons repel each other more, which increases the radius. The size is a balance of the two. Across a period, the pull of the nucleus wins. You will use these two factors for the first transition series."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: شدّ الـ protons قصاد الزقّ اللي بين الـ electrons."},"b":{"why":"الـ protons positive والـ electrons negative، والـ charges المختلفة بتتجاذب، فالـ nucleus بتشد الـ electrons لجوه.","feedback":"الفكرة الغلط: إنك تعكس دور التجاذب ودور التنافر."},"c":{"why":"الـ neutrons مالهاش charge. الـ protons اللي في الـ nucleus هي اللي بتجذب الـ electrons الـ negative.","feedback":"الفكرة الغلط: إن الـ neutrons هي اللي ماسكة الـ electrons، والـ protons بتزقّهم بعيد."},"d":{"why":"الـ electrons كلها negative، واتنين negative charges بيتنافروا، فالـ electrons بتزق بعضها بعيد.","feedback":"الفكرة الغلط: إن الـ electrons بتجذب بعضها."}},"explanation":"فيه عاملين شغالين في نفس الوقت. protons أكتر بتجذب الـ electrons أقوى، وده بيقلّل الـ radius. و electrons أكتر بتتنافر مع بعض أكتر، وده بيزوّد الـ radius. والحجم بيطلع من التوازن بين الاتنين. ولما تمشي في الـ period، شدّ الـ nucleus هو اللي بيكسب. وهتستخدم العاملين دول في الـ first transition series."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":33,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"}]},{"id":"chem-s3-en.question-pt.ionization-energy-1","kind":"question","version":1,"ord":207,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"pt.ionization-energy","concepts":[{"concept_id":"pt.ionization-energy","role":"primary"}],"title":"chem-s3-en.question-pt.ionization-energy-1","payload":{"stem":"Which equation represents the first ionization energy of calcium?","tags":["diagnostic","book_ref:Ch.1 point 5, p.10 (ionization potentials; background)"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"$\\ce{Ca(g) -> Ca+(g) + e-}$","correct":true},{"id":"b","text":"$\\ce{Ca(s) -> Ca+(s) + e-}$","correct":false},{"id":"c","text":"$\\ce{Ca(g) + e- -> Ca^{-}(g)}$","correct":false},{"id":"d","text":"$\\ce{Ca(g) -> Ca^{2+}(g) + 2e-}$","correct":false}],"book_ref":"Ch.1 point 5, p.10 (ionization potentials; background)","difficulty":2,"concept_ids":["pt.ionization-energy"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: one electron leaves a gaseous atom."},"b":{"why":"Here the calcium is a solid (s). The definition removes the electron from a gaseous atom.","feedback":"Misconception: Ionization energy is measured on the solid metal."},"c":{"why":"Ionization energy is about removing an electron, but here an electron is added.","feedback":"Misconception: Ionization means gaining an electron."},"d":{"why":"The first ionization energy removes one electron, but here two electrons leave.","feedback":"Misconception: The first ionization energy removes all the outer electrons."}},"explanation":"The book's term is ionization potential (also called ionization energy). It is the energy to remove the most loosely held electron from a gaseous atom. So the atom must be a gas, and only one electron leaves. Its unit is kJ/mol. Removing the next electron is a separate step: the second ionization energy."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: electron واحد بيطلع من ذرة في الحالة الغازية."},"b":{"why":"الـ calcium هنا solid (s). والتعريف بيشيل الـ electron من ذرة في الحالة الغازية.","feedback":"الفكرة الغلط: إن الـ ionization energy بتتقاس على الـ metal وهو صلب."},"c":{"why":"الـ ionization energy بتتكلم عن شيل electron، لكن هنا فيه electron بيتضاف.","feedback":"الفكرة الغلط: إن الـ ionization معناه إن الذرة تكسب electron."},"d":{"why":"الـ first ionization energy بتشيل electron واحد بس، لكن هنا 2 electrons بيطلعوا.","feedback":"الفكرة الغلط: إن الـ first ionization energy بتشيل الـ outer electrons كلهم."}},"explanation":"الكتاب بيسميها ionization potential، وبيتقال عليها كمان ionization energy. وهي الطاقة اللي محتاجينها عشان نشيل أضعف electron مربوط في ذرة وهي في الحالة الغازية. يعني الذرة لازم تبقى gas، و electron واحد لوحده هو اللي بيطلع. ووحدتها kJ/mol. أما شيل الـ electron اللي بعده فده خطوة منفصلة: الـ second ionization energy."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":34,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.vanadium-ie","section_title":"Successive ionization energies of vanadium","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Successive ionization energies of vanadium"],"relation":"beyond"}]},{"id":"chem-s3-en.question-pt.ionization-energy-2","kind":"question","version":2,"ord":208,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"pt.ionization-energy","concepts":[{"concept_id":"pt.ionization-energy","role":"primary"}],"title":"chem-s3-en.question-pt.ionization-energy-2","payload":{"stem":"The successive ionization potentials (also called ionization energies) of a metal X are 520, 7298 and 11815 kJ/mol. Which oxidation state does X show in its compounds?","tags":["diagnostic","book_ref:Ch.1 point 5, p.10 (ionization potentials; background)"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"+1","correct":true},{"id":"b","text":"+3","correct":false},{"id":"c","text":"+2","correct":false},{"id":"d","text":"Several states, because the values keep rising","correct":false}],"book_ref":"Ch.1 point 5, p.10 (ionization potentials; background)","difficulty":2,"concept_ids":["pt.ionization-energy"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: the big jump comes right after the 1st electron."},"b":{"why":"Counting the values does not give the oxidation state. 7298 is about 14 times 520, so the 2nd electron is not removed in its compounds.","feedback":"Misconception: The number of values given is the oxidation state."},"c":{"why":"The big jump is between the 1st and 2nd values (520 → 7298), not between the 2nd and 3rd.","feedback":"Misconception: Reading the big jump one step too late."},"d":{"why":"Every list of successive values rises. What matters is the size of each step, and the big one comes after the 1st electron.","feedback":"Misconception: Any rise in successive ionization energies means several oxidation states."}},"explanation":"Compare each value with the one before. 520 → 7298 is about 14 times larger: a big jump. So the 2nd electron must leave a stable inner level. X gives up only one electron, so it shows +1. (X is lithium, group IA.) The big jump tells you a representative metal's oxidation state."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: القفزة الكبيرة جت على طول بعد الـ electron الأول."},"b":{"why":"عدد القيم مش هو اللي بيدّي الـ oxidation state. الـ 7298 حوالي 14 ضعف الـ 520، يعني الـ electron التاني مش بيطلع في الـ compounds بتاعته.","feedback":"الفكرة الغلط: إن عدد القيم اللي في السؤال هو الـ oxidation state."},"c":{"why":"القفزة الكبيرة بين القيمة الأولى والتانية (520 → 7298)، مش بين التانية والتالتة.","feedback":"الفكرة الغلط: إنك تقرا القفزة الكبيرة متأخر بخطوة."},"d":{"why":"أي قايمة قيم متتالية بتزيد. المهم حجم كل خطوة، والخطوة الكبيرة بتيجي بعد أول electron.","feedback":"الفكرة الغلط: إن أي زيادة في الـ successive ionization energies معناها oxidation states كتير."}},"explanation":"قارن كل قيمة باللي قبلها. من 520 لـ 7298 الزيادة حوالي 14 ضعف: دي قفزة كبيرة. يعني الـ electron التاني لازم يطلع من مستوى داخلي مستقر. فالـ X بيدّي electron واحد لوحده، ويظهر بـ +1. (الـ X ده هو الـ lithium، group IA.) والقفزة الكبيرة هي اللي بتقولك الـ oxidation state بتاع الـ representative metal."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":35,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.vanadium-ie","section_title":"Successive ionization energies of vanadium","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Successive ionization energies of vanadium"],"relation":"beyond"}]},{"id":"chem-s3-en.question-te.electron-configuration-1","kind":"question","version":1,"ord":209,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.electron-configuration","concepts":[{"concept_id":"te.electron-configuration","role":"primary"},{"concept_id":"atom.hund-rule","role":"secondary"}],"title":"chem-s3-en.question-te.electron-configuration-1","payload":{"stem":"Give reasons: The 3d sublevel of the manganese atom ($_{25}$Mn) contains five unpaired electrons, while that of the iron atom ($_{26}$Fe) contains only four.","tags":["exam-style","give-reasons","book_ref:Ch.1 p.8 point 1"],"type":"short","bloom":"understand","answer":"Key points: (1) Mn: [Ar] 4s² 3d⁵; Fe: [Ar] 4s² 3d⁶. (2) Hund's rule: the five 3d orbitals are filled by a single electron in each orbital (parallel spins) before any pairing. (3) In Mn the five 3d electrons occupy the five orbitals singly → 5 unpaired. (4) In Fe the sixth 3d electron must pair with one of them (opposite spin) → 4 unpaired.","difficulty":2,"concept_ids":["te.electron-configuration","atom.hund-rule"],"est_seconds":120},"layer":{"explanation":"Model answer: Mn is [Ar] 4s² 3d⁵ and Fe is [Ar] 4s² 3d⁶. By Hund's rule, the five 3d orbitals are first filled by a single electron in each orbital (parallel spins), and only then does pairing begin. In Mn, the five 3d electrons go one into each orbital, so all 5 are unpaired: [↑] [↑] [↑] [↑] [↑]. In Fe, the sixth 3d electron finds no empty orbital, so it pairs with one electron (opposite spin), leaving 4 unpaired: [↑↓] [↑] [↑] [↑] [↑]. The book puts it this way: the 3d orbitals are filled by a single electron in each orbital till manganese ($3d^5$), and after manganese pairing takes place till zinc ($3d^{10}$). Words your exam answer must contain: Hund's rule, single electron in each orbital, pairing, unpaired. Most common mistake: \"Fe has more electrons, so it has more unpaired electrons.\" The number of unpaired electrons rises only up to $3d^5$ and then falls."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الإجابة النموذجية: الـ Mn هو [Ar] 4s² 3d⁵ والـ Fe هو [Ar] 4s² 3d⁶. حسب الـ Hund's rule، الـ 3d orbitals الخمسة بيتملوا الأول بـ single electron in each orbital (والـ spins متوازية)، وبعد كده تبدأ الـ pairing. في الـ Mn، الـ 5 electrons بتوع الـ 3d بيدخلوا كل واحد في orbital، فالـ 5 كلهم unpaired: [↑] [↑] [↑] [↑] [↑]. أما في الـ Fe، الـ electron السادس في الـ 3d مش لاقي orbital فاضي، فبيعمل زوج مع electron تاني (spin عكسه)، ويفضل 4 unpaired: [↑↓] [↑] [↑] [↑] [↑]. الكتاب بيقولها كده: the 3d orbitals are filled by a single electron in each orbital till manganese ($3d^5$), and after manganese pairing takes place till zinc ($3d^{10}$). الكلمات اللي لازم تكون في إجابتك في الامتحان: Hund's rule، single electron in each orbital، pairing، unpaired. أشهر غلطة: «الـ Fe فيه electrons أكتر، يبقى فيه unpaired electrons أكتر». عدد الـ unpaired electrons بيزيد لحد الـ $3d^5$ تحديدًا، وبعدين بيقل."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":36,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.cr-cu-anomaly-1","kind":"question","version":1,"ord":210,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.cr-cu-anomaly","concepts":[{"concept_id":"te.cr-cu-anomaly","role":"primary"}],"title":"chem-s3-en.question-te.cr-cu-anomaly-1","payload":{"stem":"Give reasons: The copper atom ($_{29}$Cu) has only one electron in its 4s sublevel, while the nickel atom ($_{28}$Ni) has two.","tags":["exam-style","give-reasons","book_ref:Ch.1 point 2, pp.8-9"],"type":"short","bloom":"understand","answer":"Key points: (1) Ni: [Ar] 4s² 3d⁸ follows the expected pattern. (2) Cu is [Ar] 4s¹ 3d¹⁰, not the expected [Ar] 4s² 3d⁹ (abnormal configuration). (3) In Cu, 4s is half filled and 3d is filled (d¹⁰). (4) The atom has lower energy (extra stability) when its d sublevel is filled (d¹⁰) or half filled (d⁵).","book_ref":"Ch.1 point 2, pp.8-9","difficulty":3,"concept_ids":["te.cr-cu-anomaly"],"est_seconds":120},"layer":{"explanation":"Ni follows the pattern: [Ar] $4s^2\\,3d^8$. By the same pattern, Cu would be [Ar] $4s^2\\,3d^9$. But the real copper atom is [Ar] $4s^1\\,3d^{10}$. Now 3d is filled ($d^{10}$) and 4s is half filled. This gives the atom lower energy, so it has extra stability. The book adds that this is not the only factor. Key words: abnormal configuration, filled ($d^{10}$), half filled, lower energy, extra stability. Most likely wrong answer: writing Cu as [Ar] $4s^2\\,3d^9$, like the pattern. That misses the extra stability of a filled 3d."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ Ni ماشي على القاعدة: [Ar] $4s^2\\,3d^8$. ولو مشينا بنفس القاعدة، الـ Cu المفروض يبقى [Ar] $4s^2\\,3d^9$. لكن ذرة الـ copper الحقيقية توزيعها [Ar] $4s^1\\,3d^{10}$. كده الـ 3d بقى filled ($d^{10}$) والـ 4s بقى half filled. الترتيب ده بيدّي الذرة lower energy، فبيبقى عندها extra stability. والكتاب بيضيف إن ده مش العامل الوحيد. الكلمات المفتاحية: abnormal configuration، filled ($d^{10}$)، half filled، lower energy، extra stability. أشهر غلطة: إنك تكتب الـ Cu كـ [Ar] $4s^2\\,3d^9$ زي القاعدة، وكده بتفوّت الـ extra stability بتاعة الـ 3d لما يبقى filled."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":37,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.ion-configuration-1","kind":"question","version":1,"ord":211,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.ion-configuration","concepts":[{"concept_id":"te.ion-configuration","role":"primary"},{"concept_id":"atom.hund-rule","role":"secondary"},{"concept_id":"pt.oxidation-number","role":"secondary"}],"title":"chem-s3-en.question-te.ion-configuration-1","payload":{"stem":"Arrange the following compounds in ascending order according to the number of unpaired electrons in the 3d sublevel of the metal ion: $\\ce{MnO}$, $\\ce{V2O5}$, $\\ce{CoCl3}$, $\\ce{NiO}$\n(V = 23, Mn = 25, Co = 27, Ni = 28)","tags":["exam-style","arrange","unpaired-electrons","book_ref:Ch.1 point 3, p.9; oxidation-states table, p.8"],"type":"order","bloom":"analyze","answer":["v2o5","nio","cocl3","mno"],"choices":[{"id":"mno","text":"$\\ce{MnO}$"},{"id":"v2o5","text":"$\\ce{V2O5}$"},{"id":"cocl3","text":"$\\ce{CoCl3}$"},{"id":"nio","text":"$\\ce{NiO}$"}],"book_ref":"Ch.1 point 3, p.9; oxidation-states table, p.8","difficulty":5,"concept_ids":["te.ion-configuration","pt.oxidation-number","atom.hund-rule"],"est_seconds":150},"layer":{"choices":{"mno":{"why":"The manganese ion of this oxide is 3d⁵: each of the five orbitals holds one electron, so 5 are unpaired.","feedback":"Misconception: Mn has 7 electrons in 4s and 3d, so its ion has few unpaired electrons."},"nio":{"why":"This nickel ion has eight 3d electrons; filling five boxes by Hund's rule leaves 2 unpaired.","feedback":"Misconception: More 3d electrons means more unpaired electrons."},"v2o5":{"why":"Vanadium is +5 here, so the ion loses all five electrons beyond [Ar] and keeps no 3d electrons.","feedback":"Misconception: Counting the vanadium atom (3d³) instead of the ion in the compound."},"cocl3":{"why":"Cobalt is +3 in $\\ce{CoCl3}$; removing the 4s electrons first leaves the ion with 3d⁶, 4 unpaired, not the atom's count.","feedback":"Misconception: Counting the cobalt atom (3d⁷, 3 unpaired) instead of Co³⁺."}},"explanation":"Step 1: find the oxidation states (O = −2, Cl = −1). V +5, Mn +2, Co +3, Ni +2. Step 2: write each ion, removing the 4s electrons first. $\\ce{V^{5+}}$ is [Ar] $3d^0$. $\\ce{Mn^{2+}}$ is [Ar] $3d^5$. $\\ce{Co^{3+}}$ is [Ar] $3d^6$. $\\ce{Ni^{2+}}$ is [Ar] $3d^8$. Step 3: fill the 3d boxes by Hund's rule. $3d^0$ → 0, $3d^8$ → 2, $3d^6$ → 4, $3d^5$ → 5. Order: $\\ce{V2O5}$ (0) < $\\ce{NiO}$ (2) < $\\ce{CoCl3}$ (4) < $\\ce{MnO}$ (5). Most likely wrong answer: counting the atoms (V 3, Ni 2, Co 3, Mn 5). Find the ion in the compound first. Another error: ordering by atomic number, from the idea 'more electrons, more unpaired'."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"mno":{"why":"الـ manganese ion بتاع الـ oxide ده 3d⁵: كل مربع من الخمسة فيه electron واحد، فيه 5 unpaired.","feedback":"الفكرة الغلط: إن الـ Mn عنده 7 electrons في الـ 4s والـ 3d، فالـ ion بتاعه عنده unpaired electrons قليلة."},"nio":{"why":"الـ nickel ion ده فيه تمن 3d electrons؛ لما تتملا الخمس مربعات حسب الـ Hund's rule بيفضل 2 unpaired.","feedback":"الفكرة الغلط: إن 3d electrons أكتر معناها unpaired electrons أكتر."},"v2o5":{"why":"الـ vanadium هنا بـ +5، فالـ ion بيفقد الخمس electrons اللي بعد الـ [Ar] كلهم ومابيفضلش معاه أي 3d electrons.","feedback":"الفكرة الغلط: إنك تعد ذرة الـ vanadium (3d³) بدل الـ ion اللي في الـ compound."},"cocl3":{"why":"الـ cobalt بـ +3 في الـ $\\ce{CoCl3}$؛ لما الـ 4s electrons تمشي الأول، الـ ion بيفضل 3d⁶ وفيه 4 unpaired، مش عدد الذرة.","feedback":"الفكرة الغلط: إنك تعد ذرة الـ cobalt (3d⁷، يعني 3 unpaired) بدل الـ Co³⁺."}},"explanation":"الخطوة 1: هات الـ oxidation states (O = −2، Cl = −1). يطلع V +5، Mn +2، Co +3، Ni +2. الخطوة 2: اكتب كل ion، وشيل الـ 4s electrons الأول. الـ $\\ce{V^{5+}}$ يبقى [Ar] $3d^0$. الـ $\\ce{Mn^{2+}}$ يبقى [Ar] $3d^5$. الـ $\\ce{Co^{3+}}$ يبقى [Ar] $3d^6$. الـ $\\ce{Ni^{2+}}$ يبقى [Ar] $3d^8$. الخطوة 3: املا مربعات الـ 3d حسب الـ Hund's rule. $3d^0$ ← 0، $3d^8$ ← 2، $3d^6$ ← 4، $3d^5$ ← 5. الترتيب: $\\ce{V2O5}$ (0) < $\\ce{NiO}$ (2) < $\\ce{CoCl3}$ (4) < $\\ce{MnO}$ (5). أشهر غلطة: إنك تعد الذرات نفسها (V 3، Ni 2، Co 3، Mn 5). هات الـ ion اللي في الـ compound الأول. وغلطة تانية: إنك ترتب حسب الـ atomic number، من فكرة إن «electrons أكتر يعني unpaired أكتر»."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":38,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.fe2-fe3-mn2-stability-1","kind":"question","version":1,"ord":212,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.fe2-fe3-mn2-stability","concepts":[{"concept_id":"te.fe2-fe3-mn2-stability","role":"primary"},{"concept_id":"te.ion-configuration","role":"secondary"}],"title":"chem-s3-en.question-te.fe2-fe3-mn2-stability-1","payload":{"stem":"Give reasons: The $\\ce{Fe^{3+}}$ ion is more stable than the $\\ce{Fe^{2+}}$ ion, while the $\\ce{Mn^{2+}}$ ion is more stable than the $\\ce{Mn^{3+}}$ ion. ($_{25}$Mn, $_{26}$Fe)","tags":["exam-style","give-reasons","book_ref:Ch.1 worked exercise, p.9"],"type":"short","bloom":"understand","answer":"Key points: (1) Fe²⁺: [Ar] 3d⁶; Fe³⁺: [Ar] 3d⁵. (2) Mn²⁺: [Ar] 3d⁵; Mn³⁺: [Ar] 3d⁴. (3) In each pair, the more stable ion has a half-filled 3d sublevel (3d⁵). (4) A half-filled 3d sublevel is more stable. (5) So Fe²⁺ is easily oxidized to Fe³⁺, but Mn²⁺ is not readily oxidized to Mn³⁺.","book_ref":"Ch.1 worked exercise, p.9","difficulty":3,"concept_ids":["te.fe2-fe3-mn2-stability","te.ion-configuration"],"est_seconds":120},"layer":{"explanation":"Remove the 4s electrons first, then 3d electrons. $\\ce{Fe^{2+}}$ is [Ar] $3d^6$ and $\\ce{Fe^{3+}}$ is [Ar] $3d^5$. $\\ce{Mn^{2+}}$ is [Ar] $3d^5$ and $\\ce{Mn^{3+}}$ is [Ar] $3d^4$. In both pairs, the more stable ion has the half-filled $3d^5$ sublevel. So the charge is not the reason: iron prefers +3, but manganese prefers +2. This is why iron (II) is easily oxidized, while Mn (II) is not readily oxidized. Key words: half-filled 3d sublevel ($3d^5$), more stable. Most likely wrong answer: 'a bigger charge is more stable'. Manganese shows that this idea fails."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"شيل الـ 4s electrons الأول، وبعدين الـ 3d electrons. الـ $\\ce{Fe^{2+}}$ تركيبه [Ar] $3d^6$ والـ $\\ce{Fe^{3+}}$ تركيبه [Ar] $3d^5$. الـ $\\ce{Mn^{2+}}$ تركيبه [Ar] $3d^5$ والـ $\\ce{Mn^{3+}}$ تركيبه [Ar] $3d^4$. في الحالتين، الـ ion الأكتر استقرارًا هو اللي الـ sublevel بتاعه $3d^5$ نصه مليان. يعني الـ charge مش هو السبب: الـ iron بيفضّل +3، إنما الـ manganese بيفضّل +2. وعشان كده الـ iron (II) بيتأكسد بسهولة، والـ Mn (II) مش بيتأكسد بسهولة. الكلمات المفتاحية: half-filled 3d sublevel ($3d^5$)، more stable. أشهر غلطة: إنك تقول «الـ charge الأكبر أكتر استقرارًا»، والـ manganese بيوريك إن الفكرة دي غلط."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":39,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"exercise":"Exercise","relation":"from_book"}]},{"id":"chem-s3-en.question-te.oxidation-states-trend-1","kind":"question","version":1,"ord":213,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.oxidation-states-trend","concepts":[{"concept_id":"te.oxidation-states-trend","role":"primary"},{"concept_id":"pt.oxidation-number","role":"secondary"}],"title":"chem-s3-en.question-te.oxidation-states-trend-1","payload":{"stem":"In which of the following compounds does manganese show the highest oxidation state? (K = +1, O = −2, $\\ce{SO4}$ group = −2)","tags":["exam-style","choose","book_ref:Ch.1 oxidation-states table, p.8 (Mn compounds)"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$\\ce{K2MnO4}$","correct":true},{"id":"b","text":"$\\ce{Mn2O3}$","correct":false},{"id":"c","text":"$\\ce{MnSO4}$","correct":false},{"id":"d","text":"$\\ce{MnO}$","correct":false}],"book_ref":"Ch.1 oxidation-states table, p.8 (Mn compounds)","difficulty":2,"concept_ids":["te.oxidation-states-trend","pt.oxidation-number"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: 2(+1) + x + 4(−2) = 0, so Mn is +6."},"b":{"why":"Three O atoms give −6, shared by two Mn atoms: 2x + 3(−2) = 0, so each Mn is +3.","feedback":"Misconception: The compound with more O atoms in its formula has the higher state."},"c":{"why":"The O atoms of $\\ce{SO4}$ are not counted one by one: the whole group is −2, so Mn is +2.","feedback":"Misconception: Counting every O atom of the sulphate group as −2."},"d":{"why":"$\\ce{Mn^{2+}}$ is the most stable manganese ion, but 'most stable' is not the same as 'highest': Mn is +2 in $\\ce{MnO}$.","feedback":"Misconception: The most stable oxidation state is the highest one."}},"explanation":"Find manganese (x) in each compound. $\\ce{K2MnO4}$: 2(+1) + x + 4(−2) = 0, so x = +6. $\\ce{Mn2O3}$: 2x + 3(−2) = 0, so x = +3. $\\ce{MnSO4}$: x + (−2) = 0, so x = +2. $\\ce{MnO}$: x = +2. The highest here is +6, in $\\ce{K2MnO4}$. Manganese reaches +7, its maximum, in $\\ce{KMnO4}$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: 2(+1) + x + 4(−2) = 0، يعني الـ Mn هنا +6."},"b":{"why":"فيه تلات ذرات O بيدوا −6، وبيتقسموا على ذرتين Mn، فكل ذرة Mn هنا +3، ودي مش الأعلى.","feedback":"الفكرة الغلط: إن الـ compound اللي في صيغته ذرات O أكتر يبقى الـ state فيه أعلى."},"c":{"why":"الـ $\\ce{SO4}$ group كلها بتتحسب −2، مش كل ذرة O لوحدها، فالـ Mn في الـ compound ده +2.","feedback":"الفكرة الغلط: إنك تحسب كل ذرة O في الـ sulphate group بـ −2."},"d":{"why":"الـ $\\ce{Mn^{2+}}$ هو أكتر ion مستقر للـ manganese، لكن «الأكتر استقرارًا» مش معناه «الأعلى»: الـ Mn هنا +2 في $\\ce{MnO}$.","feedback":"الفكرة الغلط: إن أكتر oxidation state مستقر هو نفسه الأعلى."}},"explanation":"هات الـ manganese (x) في كل compound. $\\ce{K2MnO4}$: 2(+1) + x + 4(−2) = 0، يعني x = +6. $\\ce{Mn2O3}$: 2x + 3(−2) = 0، يعني x = +3. $\\ce{MnSO4}$: x + (−2) = 0، يعني x = +2. $\\ce{MnO}$: x = +2. يبقى الأعلى هنا +6، في $\\ce{K2MnO4}$. والـ manganese بيوصل لـ +7، اللي هو أقصى حاجة عنده، في $\\ce{KMnO4}$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":40,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.multiple-oxidation-states-1","kind":"question","version":1,"ord":214,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.multiple-oxidation-states","concepts":[{"concept_id":"te.multiple-oxidation-states","role":"primary"},{"concept_id":"pt.ionization-energy","role":"secondary"}],"title":"chem-s3-en.question-te.multiple-oxidation-states-1","payload":{"stem":"Give reasons: Potassium ($_{19}$K) shows one oxidation state (+1) in its compounds, while chromium ($_{24}$Cr) shows several oxidation states (+2, +3, +6).","tags":["exam-style","give-reasons","compare","book_ref:Ch.1 point 5, p.10"],"type":"short","bloom":"understand","answer":"Key points: (1) K: [Ar] 4s¹; after the 4s electron is lost, the next one must leave the stable [Ar] inner level, so the ionization energy jumps hugely and K stays at (+1). (2) Cr: [Ar] 4s¹ 3d⁵; it loses electrons from 4s and 3d in sequence. (3) The 4s and 3d sublevels are close in energy. (4) So the ionization potentials increase gradually, with no huge jump, and several oxidation states form.","book_ref":"Ch.1 point 5, p.10","difficulty":3,"concept_ids":["te.multiple-oxidation-states","pt.ionization-energy"],"est_seconds":120},"layer":{"explanation":"Potassium has one outer electron, in 4s. Its next electron would come from the stable [Ar] arrangement, nearer the nucleus. That needs far more energy (a big jump), so K shows only +1. Chromium loses electrons from 4s and 3d in sequence. These two sublevels are close in energy. So its ionization energies increase gradually, and several oxidation states can form. Key words: 4s and 3d, close in energy, in sequence, ionization potentials increase gradually. Most likely wrong answer: 'Cr has more electrons'. Calcium has 20 electrons, yet it shows only +2."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ potassium عنده electron خارجي واحد، في الـ 4s. الـ electron اللي بعده هيطلع من ترتيب الـ [Ar] المستقر، اللي أقرب للـ nucleus. وده محتاج طاقة أكبر بكتير (قفزة كبيرة)، عشان كده الـ K بيدّي +1 تحديدًا. أما الـ chromium فبيفقد electrons من الـ 4s والـ 3d بالتتابع. والـ sublevels دول قريبين من بعض في الطاقة. فالـ ionization energies بتاعته بتزيد تدريجيًا، وبيقدر يكوّن كذا oxidation state. الكلمات المهمة: 4s and 3d، close in energy، in sequence، ionization potentials increase gradually. أكتر إجابة غلط متوقعة: 'Cr has more electrons'. الـ calcium عنده 20 electron، ومع ذلك بيدّي +2 تحديدًا."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":41,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.definition-1","kind":"question","version":1,"ord":215,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.definition","concepts":[{"concept_id":"te.definition","role":"primary"}],"title":"chem-s3-en.question-te.definition-1","payload":{"stem":"Write the scientific term: An element whose d or f orbitals contain electrons but are not complete, either in its atomic state or in one of its oxidation states.","tags":["exam-style","scientific-term","book_ref:Ch.1 point 6, p.10"],"type":"short","bloom":"remember","answer":"The transition element.","book_ref":"Ch.1 point 6, p.10","difficulty":2,"concept_ids":["te.definition"],"est_seconds":45},"layer":{"explanation":"This is the book's definition of the transition element. It checks two places: the atom, and its oxidation states. One incomplete d (or f) sublevel, in either place, is enough. Incomplete means the d orbitals hold 1 to 9 electrons. Most likely wrong answer: 'd-block element'. Zinc is in the d-block, yet it is not a transition element."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"ده تعريف الكتاب للـ transition element. التعريف بيبص على مكانين: الذرة، والـ oxidation states بتاعتها. يكفي إن يكون فيه d (أو f) sublevel واحد مش مكتمل في أي مكان من الاتنين. ومعنى مش مكتمل إن الـ d orbitals فيها من 1 لـ 9 electrons. أشهر غلطة: إنك تكتب 'd-block element'. الـ zinc مثلًا في الـ d-block، ومع ذلك مش transition element."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":42,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.definition","section_title":"The transition element (definition)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","The transition element (definition)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.definition-applied-1","kind":"question","version":1,"ord":216,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.definition-applied","concepts":[{"concept_id":"te.definition-applied","role":"primary"},{"concept_id":"te.definition","role":"secondary"}],"title":"chem-s3-en.question-te.definition-applied-1","payload":{"stem":"Give reasons: Copper ($_{29}$Cu) is a transition element, while zinc ($_{30}$Zn) is not, although both atoms have a completely filled 3d sublevel.","tags":["exam-style","give-reasons","compare","book_ref:Ch.1 Exercises 1-2, pp.10-11"],"type":"short","bloom":"understand","answer":"Key points: (1) Cu atom [Ar] 4s¹ 3d¹⁰ and Zn atom [Ar] 4s² 3d¹⁰: d is completely filled in both atoms. (2) In the (+2) state, Cu²⁺ is [Ar] 3d⁹: the d sublevel is partially filled, so Cu is a transition element. (3) Zn shows only (+2): Zn²⁺ is [Ar] 3d¹⁰, still completely filled, so Zn is not. (4) The transition element has incomplete d in its atomic state or in one of its oxidation states.","book_ref":"Ch.1 Exercises 1-2, pp.10-11","difficulty":3,"concept_ids":["te.definition-applied","te.definition"],"est_seconds":120},"layer":{"explanation":"Test the atoms first. Cu is [Ar] $4s^1\\,3d^{10}$ and Zn is [Ar] $4s^2\\,3d^{10}$. Both fail: their 3d is complete. Now test the oxidation states. $\\ce{Cu^{2+}}$ is [Ar] $3d^9$: the d sublevel is partially filled. So copper is a transition element. Zinc shows only (+2), and $\\ce{Zn^{2+}}$ is [Ar] $3d^{10}$, still complete. So zinc is not a transition element. Key words: completely filled ($d^{10}$) in the atom, partially filled ($d^9$) in the (+2) state. Most likely wrong answer: 'both are in the d-block'. Position is not the book's test."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"اختبر الذرات الأول. الـ Cu هو [Ar] $4s^1\\,3d^{10}$ والـ Zn هو [Ar] $4s^2\\,3d^{10}$. الاتنين بيسقطوا هنا: الـ 3d بتاعهم مكتمل. بعد كده اختبر الـ oxidation states. الـ $\\ce{Cu^{2+}}$ هو [Ar] $3d^9$: يعني الـ d sublevel partially filled، فالـ copper يبقى transition element. أما الـ zinc فملوش غير (+2)، والـ $\\ce{Zn^{2+}}$ هو [Ar] $3d^{10}$، لسه مكتمل. يبقى الـ zinc مش transition element. الكلمات المهمة: completely filled ($d^{10}$) في الذرة، و partially filled ($d^9$) في الـ (+2) state. أكتر إجابة غلط متوقعة: «الاتنين في الـ d-block». المكان في الجدول مش هو اختبار الكتاب."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":43,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.ex1","section_title":"Coinage metals","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Coinage metals"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":11,"page_to":11,"section_key":"ch1.config.ex2","section_title":"Zinc, cadmium and mercury","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Zinc, cadmium and mercury"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.electron-configuration-2","kind":"question","version":2,"ord":217,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.electron-configuration","concepts":[{"concept_id":"te.electron-configuration","role":"primary"},{"concept_id":"atom.hund-rule","role":"secondary"}],"title":"chem-s3-en.question-te.electron-configuration-2","payload":{"stem":"Which of the following orbital diagrams represents the 3d sublevel of the cobalt atom ($_{27}$Co)?","tags":["exam-style","choose","orbital-boxes","book_ref:Ch.1 p.8 table + point 1"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"[↑↓] [↑↓] [↑] [↑] [↑]","correct":true},{"id":"b","text":"[↑↓] [↑↓] [↑↓] [↑] [  ]","correct":false,"misconception_id":"te.electron-configuration.mc1"},{"id":"c","text":"[↑↓] [↑↓] [↑↓] [↑↓] [↑]","correct":false,"misconception_id":"te.electron-configuration.mc2"},{"id":"d","text":"[↑↓] [↑↓] [↑↓] [↑] [↑]","correct":false}],"difficulty":3,"concept_ids":["te.electron-configuration","atom.hund-rule"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! Co is [Ar] 4s² 3d⁷: five electrons go in singly first, then two of them pair up, leaving 3 unpaired."},"b":{"why":"You have 7 electrons, which is right, but there is an empty box next to paired ones: by Hund's rule each 3d orbital receives one electron before any pairing starts.","feedback":"Misconception: Pairing electrons in the first 3d orbitals before the others are singly filled."},"c":{"why":"You placed all 9 electrons after [Ar] in the 3d sublevel, but, as in calcium, $[Ar]\\,4s^2$, the first two electrons after argon go into 4s.","feedback":"Misconception: Putting all electrons after [Ar] into 3d (leaving out 4s²)."},"d":{"why":"That is 8 electrons in 3d, as if one electron moved from 4s. In this series, that anomaly happens in Cr and Cu; cobalt keeps two electrons in 4s in the book's table.","feedback":"Misconception: Over-generalising the Cr/Cu anomaly: writing Co as [Ar] 4s¹ 3d⁸."}},"explanation":"Step 1: Co has Z = 27; [Ar] accounts for 18, so 9 electrons are left. Step 2: after calcium ([Ar] 4s²) the 4s sublevel is full, so the remaining $27-20=7$ electrons go into 3d: [Ar] 4s² 3d⁷ (as in the book's table). Step 3 (Hund's rule): the first 5 electrons go one into each orbital with parallel spins, and electrons 6 and 7 pair up in the first two orbitals: [↑↓] [↑↓] [↑] [↑] [↑] → 3 unpaired. Common mistakes: an empty box next to pairs (ignoring Hund's rule), 9 electrons in 3d (forgetting 4s²), or 8 in 3d (applying the Cr/Cu anomaly to Co)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ Co هو [Ar] 4s² 3d⁷: أول 5 electrons بيدخلوا فرادى، وبعدين 2 منهم بيعملوا أزواج، فيفضل 3 unpaired."},"b":{"why":"عندك 7 electrons، وده صح، لكن فيه مربع فاضي جنب مربعات فيها أزواج: حسب الـ Hund's rule كل 3d orbital بياخد electron واحد قبل ما أي أزواج تبدأ.","feedback":"الفكرة الغلط: إن الـ electrons تعمل أزواج في أول 3d orbitals قبل ما باقي الـ orbitals ياخدوا electron واحد."},"c":{"why":"إنت حطيت الـ 9 electrons اللي بعد الـ [Ar] كلهم في الـ 3d sublevel، لكن زي الـ calcium، $[Ar]\\,4s^2$، أول 2 electrons بعد الـ argon بيروحوا الـ 4s.","feedback":"الفكرة الغلط: إن كل الـ electrons اللي بعد الـ [Ar] تتحط في الـ 3d (ومن غير الـ 4s²)."},"d":{"why":"كده فيه 8 electrons في الـ 3d، كأن electron نقل من الـ 4s. في السلسلة دي الاستثناء ده بيحصل في الـ Cr والـ Cu تحديدًا؛ الـ cobalt بيحتفظ بـ 2 electrons في الـ 4s في جدول الكتاب.","feedback":"الفكرة الغلط: تعميم استثناء الـ Cr/Cu، وكتابة الـ Co على إنه [Ar] 4s¹ 3d⁸."}},"explanation":"الخطوة 1: الـ Co عنده Z = 27؛ الـ [Ar] واخد 18، فيفضل 9 electrons. الخطوة 2: بعد الـ calcium ([Ar] 4s²) الـ 4s sublevel بيبقى مليان، فالـ electrons الباقيين $27-20=7$ بيدخلوا الـ 3d: [Ar] 4s² 3d⁷ (زي جدول الكتاب). الخطوة 3 (الـ Hund's rule): أول 5 electrons بيدخلوا واحد في كل orbital والـ spins متوازية، والـ electron السادس والسابع بيعملوا أزواج في أول اتنين orbitals: [↑↓] [↑↓] [↑] [↑] [↑] → يعني 3 unpaired. غلطات بتتكرر: مربع فاضي جنب أزواج (تجاهل الـ Hund's rule)، أو 9 electrons في الـ 3d (نسيان الـ 4s²)، أو 8 في الـ 3d (تطبيق استثناء الـ Cr/Cu على الـ Co)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":44,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.cr-cu-anomaly-2","kind":"question","version":1,"ord":218,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.cr-cu-anomaly","concepts":[{"concept_id":"te.cr-cu-anomaly","role":"primary"},{"concept_id":"te.d-block-groups","role":"secondary"}],"title":"chem-s3-en.question-te.cr-cu-anomaly-2","payload":{"stem":"Element X lies in group VIB of the first transition series. Which is the electronic configuration of its atom?","tags":["exam-style","two-step","book_ref:Ch.1 table + point 2, pp.8-9"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"[Ar] $4s^1\\,3d^5$","correct":true},{"id":"b","text":"[Ar] $4s^2\\,3d^4$","correct":false},{"id":"c","text":"[Ar] $4s^2\\,3d^5$","correct":false},{"id":"d","text":"[Ar] $3d^6$","correct":false}],"book_ref":"Ch.1 table + point 2, pp.8-9","difficulty":3,"concept_ids":["te.cr-cu-anomaly","te.d-block-groups"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: X is chromium, and both 4s and 3d are half filled."},"b":{"why":"That follows the general pattern, but the group VIB element, chromium, is one of the exceptions to it.","feedback":"Misconception: Cr follows the general pattern: [Ar] 4s² 3d⁴."},"c":{"why":"That configuration has 25 electrons, so it belongs to element 25, which is in group VIIB, not VIB.","feedback":"Misconception: Misplacing the element: taking the group VIIB element for group VIB."},"d":{"why":"The book shows no atom of this series with an empty 4s: X keeps one electron in 4s.","feedback":"Misconception: Over-generalizing the anomaly: all outer electrons move into 3d."}},"explanation":"Step 1: find X. Group IIIB is Sc (21), IVB is Ti (22) and VB is V (23). So group VIB is Cr (24). Step 2: write Cr as the book does. The expected pattern gives [Ar] $4s^2\\,3d^4$, with one empty 3d orbital. The real atom is [Ar] $4s^1\\,3d^5$. Both 4s and 3d are half filled, so the atom has lower energy (extra stability)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ X هو الـ chromium، والـ 4s والـ 3d الاتنين half filled."},"b":{"why":"ده ماشي على القاعدة العامة، لكن عنصر الـ group VIB، الـ chromium، من الاستثناءات بتاعتها.","feedback":"الفكرة الغلط: إن الـ Cr ماشي على القاعدة العامة: [Ar] 4s² 3d⁴."},"c":{"why":"التوزيع ده فيه 25 electron، يعني بتاع العنصر رقم 25، وده في الـ group VIIB مش VIB.","feedback":"الفكرة الغلط: إنك تحط العنصر في غير مكانه، فتاخد عنصر الـ group VIIB على إنه بتاع الـ group VIB."},"d":{"why":"الكتاب مابيورّيش أي ذرة في السلسلة دي والـ 4s بتاعها فاضي: الـ X بيحتفظ بـ electron واحد في الـ 4s.","feedback":"الفكرة الغلط: إنك تعمّم الاستثناء، فكل الـ electrons الخارجية تنزل في الـ 3d."}},"explanation":"خطوة 1: نعرف الـ X. الـ group IIIB هو الـ Sc (21)، والـ IVB هو الـ Ti (22)، والـ VB هو الـ V (23). يبقى الـ group VIB هو الـ Cr (24). خطوة 2: نكتب الـ Cr زي ما الكتاب كاتبه. القاعدة العامة بتدّي [Ar] $4s^2\\,3d^4$، وفيه 3d orbital واحد فاضي. لكن الذرة الحقيقية توزيعها [Ar] $4s^1\\,3d^5$. الـ 4s والـ 3d الاتنين half filled، فالذرة بيبقى عندها lower energy (extra stability)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":45,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.ion-configuration-2","kind":"question","version":1,"ord":219,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.ion-configuration","concepts":[{"concept_id":"te.ion-configuration","role":"primary"}],"title":"chem-s3-en.question-te.ion-configuration-2","payload":{"stem":"Which is the electronic configuration of $\\ce{Ni^{3+}}$? ($_{28}$Ni: [Ar] $4s^2\\,3d^8$)","tags":["exam-style","choose","book_ref:Ch.1 point 3, p.9"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"[Ar] $3d^7$","correct":true},{"id":"b","text":"[Ar] $4s^2\\,3d^5$","correct":false},{"id":"c","text":"[Ar] $4s^1\\,3d^6$","correct":false},{"id":"d","text":"[Ar] $3d^8$","correct":false}],"book_ref":"Ch.1 point 3, p.9","difficulty":3,"concept_ids":["te.ion-configuration"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: both 4s electrons leave first, then one 3d electron."},"b":{"why":"You took all three electrons from 3d, but 4s is in the outermost level (n = 4), so its electrons leave first.","feedback":"Misconception: The last electrons added (3d) leave first."},"c":{"why":"4s still holds an electron here, but 4s is in the outermost level, so it empties completely before 3d loses an electron.","feedback":"Misconception: Electrons leave from 4s and 3d in turn."},"d":{"why":"Count: 18 + 8 = 26 electrons, but a 3+ ion of nickel has 28 − 3 = 25.","feedback":"Misconception: Removing only the two 4s electrons for any positive ion."}},"explanation":"A 3+ ion has lost 3 electrons: 28 − 3 = 25 electrons are left. 4s is in the outermost level (n = 4), so its 2 electrons leave first. The third electron then leaves 3d: $3d^8$ → $3d^7$. So $\\ce{Ni^{3+}}$ is [Ar] $3d^7$. Check: 18 + 7 = 25. The book's table lists nickel as +2, +3 and +4."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الاتنين 4s electrons بيطلعوا الأول، وبعدين 3d electron واحد."},"b":{"why":"إنت أخدت التلات electrons كلهم من الـ 3d، لكن الـ 4s في المستوى الخارجي (n = 4)، فالـ electrons بتوعه هما اللي بيمشوا الأول.","feedback":"الفكرة الغلط: إن آخر electrons دخلت (الـ 3d) هي اللي بتطلع الأول."},"c":{"why":"الـ 4s لسه فيه electron هنا، لكن الـ 4s في المستوى الخارجي، فبيفضى خالص قبل ما الـ 3d يخسر أي electron.","feedback":"الفكرة الغلط: إن الـ electrons بتطلع من الـ 4s والـ 3d بالدور."},"d":{"why":"العدد: 18 + 8 = 26 electron، لكن الـ ion الـ 3+ بتاع الـ nickel فيه 28 − 3 = 25.","feedback":"الفكرة الغلط: إنك تشيل الاتنين 4s electrons تحديدًا مع أي positive ion."}},"explanation":"الـ ion الـ 3+ فقد 3 electrons: يعني فاضل 28 − 3 = 25 electrons. الـ 4s في المستوى الخارجي (n = 4)، فالـ 2 electrons بتوعه بيطلعوا الأول. وبعدين الـ electron التالت بيطلع من الـ 3d: $3d^8$ ← $3d^7$. يبقى الـ $\\ce{Ni^{3+}}$ هو [Ar] $3d^7$. اتأكد: 18 + 7 = 25. وجدول الكتاب بيدّي الـ nickel +2 و+3 و+4."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":46,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.fe2-fe3-mn2-stability-2","kind":"question","version":1,"ord":220,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.fe2-fe3-mn2-stability","concepts":[{"concept_id":"te.fe2-fe3-mn2-stability","role":"primary"}],"title":"chem-s3-en.question-te.fe2-fe3-mn2-stability-2","payload":{"stem":"Which of the following ions becomes more stable by losing one more electron? ($_{25}$Mn, $_{26}$Fe, $_{30}$Zn)","tags":["exam-style","choose","book_ref:Ch.1 worked exercise, p.9"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"$\\ce{Fe^{2+}}$","correct":true},{"id":"b","text":"$\\ce{Mn^{2+}}$","correct":false},{"id":"c","text":"$\\ce{Fe^{3+}}$","correct":false},{"id":"d","text":"$\\ce{Zn^{2+}}$","correct":false}],"book_ref":"Ch.1 worked exercise, p.9","difficulty":2,"concept_ids":["te.fe2-fe3-mn2-stability"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: 3d⁶ → 3d⁵, a half-filled and more stable sublevel."},"b":{"why":"This ion is already $3d^5$, half filled; losing one more electron would give $3d^4$, which is less stable.","feedback":"Misconception: Reversing the cases: Mn²⁺ is the ion easily oxidized."},"c":{"why":"This ion is already $3d^5$, half filled, so losing one more electron would lose that stability.","feedback":"Misconception: A higher charge always means a more stable ion."},"d":{"why":"This ion is $3d^{10}$, filled; losing a 3d electron would make it neither half filled nor filled, so it would lose stability.","feedback":"Misconception: Every ion becomes more stable when it is oxidized."}},"explanation":"Write each ion, then picture one more electron leaving. $\\ce{Fe^{2+}}$ [Ar] $3d^6$ → [Ar] $3d^5$: it reaches a half-filled, more stable 3d. $\\ce{Mn^{2+}}$ is already $3d^5$. Losing one gives $3d^4$, which is less stable. $\\ce{Fe^{3+}}$ is also $3d^5$, so it would lose that stability. $\\ce{Zn^{2+}}$ is $3d^{10}$, filled; it would lose stability too. So only $\\ce{Fe^{2+}}$ is easily oxidized."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: 3d⁶ → 3d⁵، يعني sublevel نصه مليان وأكتر استقرارًا."},"b":{"why":"الـ ion ده أصلًا $3d^5$، half filled؛ لو خسر electron كمان هيبقى $3d^4$، وده أقل استقرارًا.","feedback":"الفكرة الغلط: إنك تعكس الحالتين وتقول إن الـ Mn²⁺ هو اللي بيتأكسد بسهولة."},"c":{"why":"الـ ion ده أصلًا $3d^5$، half filled، فلو خسر electron كمان هيضيّع الاستقرار ده.","feedback":"الفكرة الغلط: إن الـ charge الأعلى دايمًا معناه ion أكتر استقرارًا."},"d":{"why":"الـ ion ده $3d^{10}$، filled؛ لو خسر 3d electron مش هيبقى لا half filled ولا filled، فهيخسر استقراره.","feedback":"الفكرة الغلط: إن كل ion بيبقى أكتر استقرارًا لما يتأكسد."}},"explanation":"اكتب كل ion، وبعدين تخيّل إن electron كمان خرج منه. الـ $\\ce{Fe^{2+}}$ [Ar] $3d^6$ → [Ar] $3d^5$: كده وصل لـ 3d نصه مليان وأكتر استقرارًا. الـ $\\ce{Mn^{2+}}$ أصلًا $3d^5$، ولو خسر واحد هيبقى $3d^4$، وده أقل استقرارًا. الـ $\\ce{Fe^{3+}}$ هو كمان $3d^5$، فهيخسر الاستقرار ده. والـ $\\ce{Zn^{2+}}$ تركيبه $3d^{10}$، مليان، وهو كمان هيخسر استقراره. يعني مفيش غير الـ $\\ce{Fe^{2+}}$ اللي بيتأكسد بسهولة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":47,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.oxidation-states-trend-2","kind":"question","version":1,"ord":221,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.oxidation-states-trend","concepts":[{"concept_id":"te.oxidation-states-trend","role":"primary"}],"title":"chem-s3-en.question-te.oxidation-states-trend-2","payload":{"stem":"The table shows data from the book for five elements of the first transition series. Which conclusion do the data support?","tags":["exam-style","data-reading","book_ref:Ch.1 table + point 4, pp.8-9"],"type":"mcq","bloom":"analyze","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["$_{22}$Ti","IVB",4,"+4"],["$_{25}$Mn","VIIB",7,"+7"],["$_{26}$Fe","VIII",8,"+6"],["$_{29}$Cu","IB",11,"+2"],["$_{30}$Zn","IIB",12,"+2"]],"caption":"Book table, p.8 (for illustration only; Cu: +1, +2)","headers":["Element","Group","Electrons in 4s and 3d","Highest oxidation state"]},"children":[]}}},"choices":[{"id":"a","text":"The highest state equals the number of 4s and 3d electrons only up to Mn","correct":true},{"id":"b","text":"The highest state of each element equals its group number","correct":false},{"id":"c","text":"The highest state rises with the number of 4s and 3d electrons","correct":false},{"id":"d","text":"Only group IB has a highest state below its group number","correct":false}],"book_ref":"Ch.1 table + point 4, pp.8-9","difficulty":4,"concept_ids":["te.oxidation-states-trend"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Right: Ti and Mn match; Fe, Cu and Zn fall below their electron counts."},"b":{"why":"Fe and Cu break this: Fe (group VIII) reaches +6 at most, and Cu's +2 is above its group number (I).","feedback":"Misconception: The maximum oxidation state always equals the group number."},"c":{"why":"Zinc has the most 4s and 3d electrons here, yet its highest state is +2, far below Mn's +7.","feedback":"Misconception: Maximum oxidation state = number of 4s + 3d electrons for every element."},"d":{"why":"Copper's +2 is above its group number (I), not below, and iron (group VIII) also stays below its group number, at +6.","feedback":"Misconception: Group IB is the exception because its maximum is below the group number."}},"explanation":"Test each claim against every row. Ti (4 electrons, +4) and Mn (7, +7) match the electron count. Fe has 8 but reaches only +6. Cu and Zn are far below their counts. So the match holds up to Mn only. The group rule fails for Fe: group VIII, highest +6. Copper's +2 is above its group number (I), not below. The book: the maximum does not exceed the group number, except group IB."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ Ti والـ Mn ماشيين مع عدد الـ electrons؛ إنما الـ Fe والـ Cu والـ Zn أقل من عدد الـ electrons بتاعتهم."},"b":{"why":"الكلام ده مش ماشي على الـ Fe والـ Cu: الـ Fe في group VIII وأعلى state عنده +6، والـ +2 بتاع الـ Cu أعلى من رقم الـ group بتاعه.","feedback":"الفكرة الغلط: إن أعلى oxidation state دايمًا بيساوي رقم الـ group."},"c":{"why":"الـ zinc عنده أكتر عدد electrons في الـ 4s والـ 3d هنا، لكن أعلى state عنده +2، مش الأكبر في الجدول.","feedback":"الفكرة الغلط: إن أعلى oxidation state = عدد الـ electrons اللي في الـ 4s والـ 3d، لكل عنصر."},"d":{"why":"الـ +2 بتاع الـ copper أعلى من رقم الـ group بتاعه، I، مش أقل منه. والـ iron كمان أعلى state عنده (+6) أقل من رقم الـ group بتاعه (VIII).","feedback":"الفكرة الغلط: إن group IB هو الاستثناء عشان أعلى state فيه أقل من رقم الـ group."}},"explanation":"جرّب كل جملة على كل صف في الجدول. الـ Ti (4 electrons، +4) والـ Mn (7، +7) ماشيين مع عدد الـ electrons. الـ Fe عنده 8 لكن مابيوصلش لأكتر من +6. والـ Cu والـ Zn أقل من العدد بتاعهم بكتير. يعني التطابق ده ماشي لحد الـ Mn تحديدًا. وقاعدة الـ group بتقع عند الـ Fe: group VIII، وأعلى state +6. والـ +2 بتاع الـ copper أعلى من رقم الـ group بتاعه (I)، مش أقل. الكتاب بيقول: أعلى oxidation state مابيعديش رقم الـ group، ما عدا group IB."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":48,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.multiple-oxidation-states-2","kind":"question","version":1,"ord":222,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.multiple-oxidation-states","concepts":[{"concept_id":"te.multiple-oxidation-states","role":"primary"},{"concept_id":"pt.ionization-energy","role":"secondary"}],"title":"chem-s3-en.question-te.multiple-oxidation-states-2","payload":{"stem":"The table gives successive ionization energies (kJ/mol) of vanadium (book values) and of a representative metal X. Which statement is correct?","tags":["exam-style","data-reading","book_ref:Ch.1 point 5 + vanadium chart, p.10"],"type":"mcq","bloom":"analyze","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["Vanadium",648,1346,2858,4643],["X",900,1757,14849,21007]],"caption":"Successive ionization energies, kJ/mol (vanadium: book p.10)","headers":["Metal","1st","2nd","3rd","4th"]},"children":[]}}},"choices":[{"id":"a","text":"X shows one oxidation state (+2); vanadium's gradual rise allows several","correct":true},{"id":"b","text":"X shows (+4), because four of its electrons can be removed","correct":false},{"id":"c","text":"Vanadium shows only (+2), because a huge jump follows its 4s electrons","correct":false},{"id":"d","text":"Both show several oxidation states, because both lists keep rising","correct":false}],"book_ref":"Ch.1 point 5 + vanadium chart, p.10","difficulty":4,"concept_ids":["te.multiple-oxidation-states","pt.ionization-energy"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Right: X jumps after its 2nd electron, while vanadium climbs step by step."},"b":{"why":"Any atom can lose more electrons in theory, but X's values jump hugely after its 2nd electron (1757 → 14849), so X shows +2 only.","feedback":"Misconception: The number of ionization energies listed is the oxidation state."},"c":{"why":"Vanadium's values rise gradually (1346 → 2858); the huge jump is in X's values (1757 → 14849), so vanadium shows several states.","feedback":"Misconception: A huge jump appears right after the 4s electrons of a transition metal."},"d":{"why":"All successive values rise, but the size of each step is what matters: X has a big jump after its 2nd electron, so X shows one state.","feedback":"Misconception: Any rise in successive ionization energies means several oxidation states."}},"explanation":"Compare each step with the one before. X: 900 → 1757 roughly doubles. But 1757 → 14849 is about eight times larger: a big jump. The 3rd electron must leave a stable inner level, so X shows only +2. (X is beryllium, group IIA.) Vanadium: 648 → 1346 → 2858 → 4643 rises gradually, about doubling or less. Its 4s and 3d electrons are close in energy. So vanadium shows several states: +2, +3, +4 and +5."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ X بيعمل قفزة بعد الـ electron التاني بتاعه، أما الـ vanadium فبيطلع خطوة خطوة."},"b":{"why":"نظريًا أي ذرة تقدر تفقد electrons أكتر، لكن قيم الـ X بتقفز قفزة كبيرة بعد الـ electron التاني (من 1757 لـ 14849)، فالـ X مابيدّيش +4.","feedback":"الفكرة الغلط: إن عدد الـ ionization energies المكتوبة في الجدول هو الـ oxidation state."},"c":{"why":"قيم الـ vanadium بتزيد تدريجيًا من التانية للتالتة، والقفزة الكبيرة في قيم الـ X، مش الـ vanadium، فالـ vanadium بيدّي كذا state.","feedback":"الفكرة الغلط: إن فيه قفزة كبيرة بتظهر على طول بعد الـ 4s electrons بتوع الـ transition metal."},"d":{"why":"القيم المتتالية كلها بتزيد، لكن المهم هو حجم كل خطوة: الـ X فيه قفزة كبيرة بعد الـ electron التاني، فبيدّي state واحدة.","feedback":"الفكرة الغلط: إن أي زيادة في الـ successive ionization energies معناها كذا oxidation state."}},"explanation":"قارن كل خطوة باللي قبلها. الـ X: من 900 لـ 1757 تقريبًا الضعف. لكن من 1757 لـ 14849 حوالي تمن أضعاف: دي قفزة كبيرة. الـ electron التالت لازم يطلع من مستوى داخلي مستقر، عشان كده الـ X بيدّي +2 تحديدًا. (الـ X هو الـ beryllium، group IIA.) الـ vanadium: 648 → 1346 → 2858 → 4643 بتزيد تدريجيًا، تقريبًا الضعف أو أقل. والـ 4s والـ 3d electrons بتوعه قريبين من بعض في الطاقة. فالـ vanadium بيدّي كذا state: +2 و+3 و+4 و+5."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":49,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.vanadium-ie","section_title":"Successive ionization energies of vanadium","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Successive ionization energies of vanadium"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.definition-2","kind":"question","version":1,"ord":223,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.definition","concepts":[{"concept_id":"te.definition","role":"primary"}],"title":"chem-s3-en.question-te.definition-2","payload":{"stem":"Which of the following data is enough to prove that element X is a transition element?","tags":["exam-style","choose","book_ref:Ch.1 point 6, p.10"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"X atom: [Kr] $5s^2\\,4d^2$","correct":true},{"id":"b","text":"X lies in the d-block of the periodic table","correct":false,"misconception_id":"te.definition.mc1"},{"id":"c","text":"X atom: [Ar] $4s^2\\,3d^{10}$; its only ion $\\ce{X^{2+}}$: [Ar] $3d^{10}$","correct":false},{"id":"d","text":"X shows the oxidation state (+2) by losing its 4s electrons","correct":false}],"book_ref":"Ch.1 point 6, p.10","difficulty":3,"concept_ids":["te.definition"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: 4d holds 2 electrons, so it is incomplete in the atom."},"b":{"why":"Zinc is in the d-block too, yet it is not a transition element: the book's definition checks the d orbitals, not position.","feedback":"Misconception: Every d-block element is a transition element."},"c":{"why":"The d orbitals here are complete in the atom and in its only ion, so X fails the definition.","feedback":"Misconception: Having electrons in the d orbitals is enough."},"d":{"why":"Calcium also loses its two 4s electrons to give +2, and calcium is not a transition element, so (+2) proves nothing.","feedback":"Misconception: Showing +2 by losing 4s electrons defines a transition element."}},"explanation":"The definition checks the d (or f) orbitals. They must contain electrons but be incomplete, in the atom or in one of its oxidation states. [Kr] $5s^2\\,4d^2$ has 2 electrons in 4d, which is incomplete. So X is a transition element. Position in the d-block is not the test: zinc is there, but it is not one. An atom that is $d^{10}$ and whose only ion is also $d^{10}$ has a complete d sublevel in both, so it fails the definition. Calcium also loses its 4s electrons to give +2, so (+2) proves nothing."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ 4d فيه 2 electrons، يعني مش مكتمل في الذرة."},"b":{"why":"الـ zinc كمان في الـ d-block، ومع ذلك مش transition element: تعريف الكتاب بيبص على الـ d orbitals، مش على المكان.","feedback":"الفكرة الغلط: إن أي عنصر في الـ d-block يبقى transition element."},"c":{"why":"الـ d orbitals هنا مكتملة في الذرة وفي الـ ion الوحيد بتاعها، فالـ X مش بيحقق التعريف.","feedback":"الفكرة الغلط: إن وجود electrons في الـ d orbitals كفاية."},"d":{"why":"الـ calcium كمان بيخسر الـ 2 electrons بتوع الـ 4s ويدي +2، والـ calcium مش transition element، فالـ (+2) مابيثبتش حاجة.","feedback":"الفكرة الغلط: إن إظهار الـ +2 بخسارة الـ 4s electrons هو اللي بيعرّف الـ transition element."}},"explanation":"التعريف بيبص على الـ d (أو f) orbitals: لازم يكون فيها electrons لكن مش مكتملة، في الذرة أو في حالة من الـ oxidation states بتاعتها. الـ [Kr] $5s^2\\,4d^2$ فيه 2 electrons في الـ 4d، يعني مش مكتمل، فالـ X يبقى transition element. المكان في الـ d-block مش هو الاختبار: الـ zinc موجود هناك، ومع ذلك مش transition element. والذرة اللي $d^{10}$ والـ ion الوحيد بتاعها كمان $d^{10}$، الـ d sublevel مكتمل فيهم الاتنين، فمش بتعدّي التعريف. والـ calcium كمان بيخسر الـ 4s electrons بتوعه ويدي +2، فالـ (+2) مش بيثبت أي حاجة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":50,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.definition","section_title":"The transition element (definition)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","The transition element (definition)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.definition-applied-2","kind":"question","version":1,"ord":224,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.definition-applied","concepts":[{"concept_id":"te.definition-applied","role":"primary"}],"title":"chem-s3-en.question-te.definition-applied-2","payload":{"stem":"Cadmium ($_{48}$Cd: [Kr] $5s^2\\,4d^{10}$) shows only the oxidation state (+2). Why is cadmium not a transition element?","tags":["exam-style","choose","book_ref:Ch.1 Exercise 2, p.11"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Its 4d is completely filled in the atom and in the (+2) state","correct":true},{"id":"b","text":"It is in group IIB, which lies outside the d-block","correct":false},{"id":"c","text":"Its atom has a filled 4d, so it fails the definition at once","correct":false,"misconception_id":"te.definition.mc3"},{"id":"d","text":"It shows only one oxidation state in all its compounds","correct":false}],"book_ref":"Ch.1 Exercise 2, p.11","difficulty":2,"concept_ids":["te.definition-applied"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: d¹⁰ in the atom and d¹⁰ in Cd²⁺, so no incomplete d anywhere."},"b":{"why":"Group IIB is the last column of the d-block, not outside it.","feedback":"Misconception: Groups IB and IIB lie outside the d-block."},"c":{"why":"Copper's atom is also $d^{10}$, yet copper is a transition element, because $\\ce{Cu^{2+}}$ is $3d^9$. A filled d in the atom is not enough: the oxidation states are tested too.","feedback":"Misconception: Only the neutral atom is checked."},"d":{"why":"The definition says nothing about how many states; it checks whether the d orbitals are incomplete.","feedback":"Misconception: A transition element must show several oxidation states."}},"explanation":"Test the atom: [Kr] $5s^2\\,4d^{10}$, so 4d is complete. Test the (+2) state: the two 5s electrons leave first. So $\\ce{Cd^{2+}}$ is [Kr] $4d^{10}$, still complete. It fails both tests, so cadmium is not a transition element. The same holds for zinc and mercury."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: d¹⁰ في الذرة و d¹⁰ في الـ Cd²⁺، يعني مفيش d incomplete في أي حالة."},"b":{"why":"الـ group IIB هو آخر column في الـ d-block، مش برّه.","feedback":"الفكرة الغلط: إن الـ groups IB و IIB واقعين برّه الـ d-block."},"c":{"why":"ذرة الـ copper هي كمان $d^{10}$، ومع ذلك الـ copper يُعتبر transition element، عشان الـ $\\ce{Cu^{2+}}$ بيبقى $3d^9$. يعني الـ d المكتمل في الذرة مش كفاية: الـ oxidation states بتتفحص هي كمان.","feedback":"الفكرة الغلط: إن الذرة المتعادلة لوحدها هي اللي بتتفحص."},"d":{"why":"التعريف مش بيقول أي حاجة عن عدد الـ states؛ هو بيبص على الـ d orbitals: incomplete ولا لأ.","feedback":"الفكرة الغلط: إن الـ transition element لازم يكون ليه كذا oxidation state."}},"explanation":"اختبر الذرة: [Kr] $5s^2\\,4d^{10}$، يعني الـ 4d مكتمل. اختبر الـ (+2) state: الـ 2 electrons بتوع الـ 5s بيمشوا الأول، فالـ $\\ce{Cd^{2+}}$ يبقى [Kr] $4d^{10}$، لسه مكتمل. سقط في الاختبارين، يبقى الـ cadmium مش transition element. ونفس الكلام على الـ zinc والـ mercury."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":51,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":11,"page_to":11,"section_key":"ch1.config.ex2","section_title":"Zinc, cadmium and mercury","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Zinc, cadmium and mercury"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.electron-configuration-3","kind":"question","version":1,"ord":225,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.electron-configuration","concepts":[{"concept_id":"te.electron-configuration","role":"primary"},{"concept_id":"atom.hund-rule","role":"secondary"}],"title":"chem-s3-en.question-te.electron-configuration-3","payload":{"stem":"Element X belongs to the first transition series. Its atom has a completely filled 4s sublevel and the greatest number of unpaired electrons in the 3d sublevel. The atomic number of X is ...","tags":["exam-style","two-step","book_ref:Ch.1 p.8 table + point 1"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"24","correct":false},{"id":"b","text":"25","correct":true},{"id":"c","text":"26","correct":false},{"id":"d","text":"30","correct":false}],"difficulty":3,"concept_ids":["te.electron-configuration","atom.hund-rule"],"est_seconds":75},"layer":{"choices":{"a":{"why":"The 3d sublevel of the Cr atom really does have 5 unpaired electrons. But the question needs a completely filled 4s, and chromium is [Ar] 4s¹ 3d⁵: its 4s holds only one electron.","feedback":"Misconception: Ignores the 4s condition: Cr also has 3d⁵, but its atom is [Ar] 4s¹ 3d⁵."},"b":{"why":"Correct! Mn is [Ar] 4s² 3d⁵: 4s is full and each of the five 3d orbitals has one electron, so 5 unpaired, which is the maximum."},"c":{"why":"3d⁶ has more electrons, but by Hund's rule the sixth electron pairs up in one of the five boxes, so the number of unpaired electrons falls to 4.","feedback":"Misconception: More 3d electrons means more unpaired electrons."},"d":{"why":"3d¹⁰ means the most electrons in 3d, not the most unpaired ones: ten electrons in five boxes are all paired, so 0 are unpaired.","feedback":"Misconception: Confusing a completely filled 3d (3d¹⁰) with the greatest number of unpaired electrons."}},"explanation":"Step 1 (find the 3d arrangement): 3d has 5 orbitals, so the greatest number of unpaired electrons is 5. This happens at $3d^5$, when each orbital has a single electron (Hund's rule). In this series, $3d^5$ occurs in Cr and Mn. Step 2 (the 4s condition): Cr is [Ar] 4s¹ 3d⁵ (4s not full), while Mn is [Ar] 4s² 3d⁵. So X is Mn, Z = 25. Note: after Mn pairing begins, so the number of unpaired 3d electrons falls (Fe 4, Co 3, Ni 2, Zn 0) even though the number of electrons keeps rising."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"الـ 3d sublevel في ذرة الـ Cr فعلًا فيه 5 unpaired electrons. لكن السؤال شرطه 4s مليان، والـ chromium هو [Ar] 4s¹ 3d⁵: الـ 4s فيه electron واحد لوحده.","feedback":"الفكرة الغلط: تجاهل شرط الـ 4s: الـ Cr برضه عنده 3d⁵، لكن الذرة بتاعته [Ar] 4s¹ 3d⁵."},"b":{"why":"صح! الـ Mn هو [Ar] 4s² 3d⁵: الـ 4s مليان، وكل orbital من الخمسة بتوع الـ 3d فيه electron واحد، يعني 5 unpaired، وده أكبر عدد ممكن."},"c":{"why":"الـ 3d⁶ فيه electrons أكتر، لكن حسب الـ Hund's rule الـ electron السادس بيعمل زوج في واحد من المربعات الخمسة، فعدد الـ unpaired electrons بيقل لـ 4.","feedback":"الفكرة الغلط: إن electrons أكتر في الـ 3d يعني unpaired electrons أكتر."},"d":{"why":"الـ 3d¹⁰ معناه أكبر عدد electrons في الـ 3d، مش أكبر عدد unpaired: عشرة electrons في خمس مربعات كلهم أزواج، يعني 0 unpaired.","feedback":"الفكرة الغلط: الخلط بين 3d مليان على الآخر (3d¹⁰) وأكبر عدد من الـ unpaired electrons."}},"explanation":"الخطوة 1 (رتّب الـ 3d): الـ 3d فيه 5 orbitals، فأكبر عدد من الـ unpaired electrons هو 5. وده بيحصل عند الـ $3d^5$، لما يبقى في كل orbital electron واحد (الـ Hund's rule). في السلسلة دي، الـ $3d^5$ موجود في الـ Cr والـ Mn. الخطوة 2 (شرط الـ 4s): الـ Cr هو [Ar] 4s¹ 3d⁵ (الـ 4s مش مليان)، إنما الـ Mn هو [Ar] 4s² 3d⁵. يبقى X هو الـ Mn، و Z = 25. خلّي بالك: بعد الـ Mn الأزواج بتبدأ، فعدد الـ unpaired electrons في الـ 3d بيقل (Fe 4، Co 3، Ni 2، Zn 0) مع إن عدد الـ electrons بيفضل يزيد."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":52,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.cr-cu-anomaly-3","kind":"question","version":1,"ord":226,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.cr-cu-anomaly","concepts":[{"concept_id":"te.cr-cu-anomaly","role":"primary"}],"title":"chem-s3-en.question-te.cr-cu-anomaly-3","payload":{"stem":"Consider the following statements:\n(I) In the chromium atom ($_{24}$Cr), both the 4s and 3d sublevels are half filled.\n(II) In the copper atom ($_{29}$Cu), the 4s sublevel is filled and the 3d sublevel is half filled.\n(III) An atom has extra stability when its d sublevel is half filled ($d^5$) or filled ($d^{10}$).\nWhich of these statements is/are correct?","tags":["exam-style","statements-I-II-III","book_ref:Ch.1 point 2, pp.8-9"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"I and III only","correct":true},{"id":"b","text":"I, II and III","correct":false},{"id":"c","text":"III only","correct":false},{"id":"d","text":"I and II only","correct":false}],"book_ref":"Ch.1 point 2, pp.8-9","difficulty":2,"concept_ids":["te.cr-cu-anomaly"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: Cr is 4s¹ 3d⁵, Cu is 4s¹ 3d¹⁰, and half-filled or filled d gives extra stability."},"b":{"why":"(II) is wrong: the book writes Cu with one electron in 4s and ten in 3d, so 4s is half filled and 3d is filled, not the reverse.","feedback":"Misconception: Swapping the sublevels in Cu: 4s filled and 3d half filled."},"c":{"why":"(I) is correct: Cr keeps one electron in 4s and five in 3d, so both sublevels are half filled.","feedback":"Misconception: Cr keeps the pattern 4s² 3d⁴, so nothing is half filled."},"d":{"why":"(III) is correct: it is the book's reason for the Cr and Cu configurations. (II) is the wrong one, because it swaps the 4s and 3d of Cu.","feedback":"Misconception: Since the book says it is not the only factor, the d⁵/d¹⁰ stability idea is false."}},"explanation":"Cr is [Ar] $4s^1\\,3d^5$. 4s holds 1 of 2 electrons, and 3d holds 5 of 10. Both are half filled, so (I) is correct. Cu is [Ar] $4s^1\\,3d^{10}$: 4s is half filled and 3d is filled. (II) swaps them, so it is wrong. (III) is the book's reason for the anomaly, so it is correct. The book adds that this is not the only factor. Answer: I and III only."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ Cr توزيعه 4s¹ 3d⁵، والـ Cu توزيعه 4s¹ 3d¹⁰، والـ d لما يبقى half filled أو filled بيدّي extra stability."},"b":{"why":"(II) غلط: الكتاب بيكتب الـ Cu بـ electron واحد في الـ 4s وعشرة في الـ 3d، يعني الـ 4s هو اللي half filled والـ 3d هو اللي filled، مش العكس.","feedback":"الفكرة الغلط: إنك تبدّل الـ sublevels في الـ Cu، فيبقى الـ 4s filled والـ 3d half filled."},"c":{"why":"(I) صح: الـ Cr بيحتفظ بـ electron واحد في الـ 4s وخمسة في الـ 3d، فالـ sublevels الاتنين half filled.","feedback":"الفكرة الغلط: إن الـ Cr محتفظ بالقاعدة 4s² 3d⁴، فمفيش حاجة half filled."},"d":{"why":"(III) صح: ده السبب اللي الكتاب بيدّيه لتوزيع الـ Cr والـ Cu. العبارة الغلط هي (II)، لأنها بتبدّل الـ 4s والـ 3d بتوع الـ Cu.","feedback":"الفكرة الغلط: إن طالما الكتاب قال إنه مش العامل الوحيد، يبقى فكرة الـ stability بتاعة d⁵/d¹⁰ غلط."}},"explanation":"الـ Cr توزيعه [Ar] $4s^1\\,3d^5$. الـ 4s فيه 1 من 2 electrons، والـ 3d فيه 5 من 10. الاتنين half filled، يبقى (I) صح. الـ Cu توزيعه [Ar] $4s^1\\,3d^{10}$: الـ 4s half filled والـ 3d filled. و(II) بتبدّلهم، يبقى غلط. أما (III) فهي السبب اللي الكتاب بيدّيه للـ anomaly، يبقى صح. والكتاب بيضيف إن ده مش العامل الوحيد. الإجابة: I and III only."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":53,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.ion-configuration-3","kind":"question","version":1,"ord":227,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.ion-configuration","concepts":[{"concept_id":"te.ion-configuration","role":"primary"},{"concept_id":"te.cr-cu-anomaly","role":"secondary"}],"title":"chem-s3-en.question-te.ion-configuration-3","payload":{"stem":"The ion $\\ce{X+}$ of an element X in the first transition series has the configuration [Ar] $3d^{10}$. Which choice identifies X and the configuration of its atom?","tags":["exam-style","two-step","book_ref:Ch.1 points 2-3, pp.8-9"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"X is copper; [Ar] $4s^1\\,3d^{10}$","correct":true},{"id":"b","text":"X is copper; [Ar] $4s^2\\,3d^9$","correct":false},{"id":"c","text":"X is zinc; [Ar] $4s^2\\,3d^{10}$","correct":false},{"id":"d","text":"X is nickel; [Ar] $4s^2\\,3d^8$","correct":false}],"book_ref":"Ch.1 points 2-3, pp.8-9","difficulty":4,"concept_ids":["te.ion-configuration","te.cr-cu-anomaly"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right: Z = 28 + 1 = 29, and copper's atom has a filled 3d."},"b":{"why":"Copper does not follow the general pattern: its atom has a filled 3d and one 4s electron.","feedback":"Misconception: Cu follows the general pattern: [Ar] 4s² 3d⁹."},"c":{"why":"A 1+ ion lost one electron, so add back one, not two: Z = 28 + 1 = 29, not zinc's 30.","feedback":"Misconception: Adding back two 4s electrons whatever the charge."},"d":{"why":"28 is the ion's electron count; the atom has one more electron, so its Z is 29, larger than 28.","feedback":"Misconception: The electrons in the ion equal the atomic number."}},"explanation":"Step 1: count the electrons in the ion: 18 + 10 = 28. The ion lost 1 electron, so Z = 28 + 1 = 29. X is copper. Step 2: the copper atom is [Ar] $4s^1\\,3d^{10}$, an abnormal configuration with a filled 3d. Check: when the single 4s electron leaves, the ion is [Ar] $3d^{10}$. That matches the given ion."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: Z = 28 + 1 = 29، وذرة الـ copper الـ 3d بتاعها مليان."},"b":{"why":"الـ copper مش ماشي على القاعدة العامة: الذرة بتاعته فيها 3d مليان والـ 4s فيه electron واحد.","feedback":"الفكرة الغلط: إن الـ Cu ماشي على القاعدة العامة: [Ar] 4s² 3d⁹."},"c":{"why":"الـ ion الـ 1+ فقد electron واحد، فبنرجّع واحد بس، مش اتنين: Z = 28 + 1 = 29، مش الـ 30 بتاع الـ zinc.","feedback":"الفكرة الغلط: إنك ترجّع اتنين 4s electrons مهما كانت الـ charge."},"d":{"why":"الـ 28 دي عدد electrons الـ ion؛ الذرة فيها electron زيادة، فالـ Z بتاعها 29، أكبر من 28.","feedback":"الفكرة الغلط: إن عدد الـ electrons اللي في الـ ion بيساوي الـ atomic number."}},"explanation":"الخطوة 1: عِد الـ electrons اللي في الـ ion: 18 + 10 = 28. الـ ion فقد electron واحد، يبقى Z = 28 + 1 = 29، يعني X هو الـ copper. الخطوة 2: ذرة الـ copper هي [Ar] $4s^1\\,3d^{10}$، وده abnormal configuration فيه الـ 3d مليان. اتأكد: لما الـ 4s electron الوحيد يطلع، الـ ion يبقى [Ar] $3d^{10}$، وده نفس الـ ion اللي في السؤال."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":54,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.fe2-fe3-mn2-stability-3","kind":"question","version":1,"ord":228,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.fe2-fe3-mn2-stability","concepts":[{"concept_id":"te.fe2-fe3-mn2-stability","role":"primary"}],"title":"chem-s3-en.question-te.fe2-fe3-mn2-stability-3","payload":{"stem":"Consider the following statements ($_{25}$Mn, $_{26}$Fe):\n(I) When $\\ce{Fe^{2+}}$ is oxidized to $\\ce{Fe^{3+}}$, the 3d orbital that held a pair is left with one electron.\n(II) The $\\ce{Mn^{3+}}$ ion has a half-filled 3d sublevel.\n(III) The important oxidation states of iron are (+2) and (+3).\nWhich of these statements is/are correct?","tags":["exam-style","statements-I-II-III","book_ref:Ch.1 worked exercise, p.9; iron oxidation states, pp.20-21"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"I and III only","correct":true},{"id":"b","text":"I, II and III","correct":false},{"id":"c","text":"III only","correct":false},{"id":"d","text":"I and II only","correct":false}],"book_ref":"Ch.1 worked exercise, p.9; iron oxidation states, pp.20-21","difficulty":3,"concept_ids":["te.fe2-fe3-mn2-stability"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: Fe³⁺ has five unpaired 3d electrons, Mn³⁺ is 3d⁴, and iron's important states are +2 and +3."},"b":{"why":"(II) is wrong: $\\ce{Mn^{3+}}$ has lost three electrons, leaving four in its 3d, so one orbital is empty.","feedback":"Misconception: A bigger charge gives Mn³⁺ the half-filled 3d."},"c":{"why":"(I) is correct: $\\ce{Fe^{2+}}$ ($3d^6$) has one paired orbital, and in $\\ce{Fe^{3+}}$ ($3d^5$) that orbital is left with one electron.","feedback":"Misconception: The electron lost from Fe²⁺ comes from 4s or from a singly filled orbital."},"d":{"why":"(III) is correct: iron also has +6 in $\\ce{Na2FeO4}$, but the book says its states above +3 are not important. (II) is the wrong one.","feedback":"Misconception: All of iron's oxidation states, up to +6, are important."}},"explanation":"(I) $\\ce{Fe^{2+}}$ is $3d^6$: one orbital holds a pair and four hold one each. $\\ce{Fe^{3+}}$ is $3d^5$: all five hold one each. So the paired orbital lost an electron: correct. (II) $\\ce{Mn^{3+}}$ is [Ar] $3d^4$: one orbital is empty. It is not half filled, so (II) is wrong. (III) is correct: iron's states above +3 are not important. Answer: I and III only."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ Fe³⁺ فيه خمسة unpaired 3d electrons، والـ Mn³⁺ تركيبه 3d⁴، وأهم states للـ iron هي +2 و+3."},"b":{"why":"(II) غلط: الـ $\\ce{Mn^{3+}}$ خسر تلات electrons، فاضل أربعة في الـ 3d بتاعه، فيه orbital فاضي.","feedback":"الفكرة الغلط: إن الـ charge الأكبر بيدّي الـ Mn³⁺ الـ 3d اللي نصه مليان."},"c":{"why":"(I) صح: الـ $\\ce{Fe^{2+}}$ ($3d^6$) فيه orbital واحد فيه زوج، وفي الـ $\\ce{Fe^{3+}}$ ($3d^5$) الـ orbital ده بيفضل فيه electron واحد.","feedback":"الفكرة الغلط: إن الـ electron اللي بيخرج من الـ Fe²⁺ بييجي من الـ 4s أو من orbital فيه electron واحد."},"d":{"why":"(III) صح: الـ iron عنده كمان +6 في الـ $\\ce{Na2FeO4}$، لكن الكتاب بيقول إن الـ states بتاعته اللي فوق +3 مش مهمة. العبارة الغلط هي (II).","feedback":"الفكرة الغلط: إن كل الـ oxidation states بتاعة الـ iron، لحد +6، مهمة."}},"explanation":"(I) الـ $\\ce{Fe^{2+}}$ تركيبه $3d^6$: orbital واحد فيه زوج، وأربعة فيهم electron واحد في كل واحد. الـ $\\ce{Fe^{3+}}$ تركيبه $3d^5$: الخمسة كلهم فيهم electron واحد. يعني الـ orbital اللي كان فيه زوج هو اللي خسر electron: العبارة صح. (II) الـ $\\ce{Mn^{3+}}$ تركيبه [Ar] $3d^4$: فيه orbital فاضي، فهو مش نصه مليان، يعني (II) غلط. (III) صح: الـ states بتاعة الـ iron اللي فوق +3 مش مهمة. الإجابة: I and III only."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":55,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.oxidation-states-trend-3","kind":"question","version":1,"ord":229,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.oxidation-states-trend","concepts":[{"concept_id":"te.oxidation-states-trend","role":"primary"},{"concept_id":"pt.oxidation-number","role":"secondary"}],"title":"chem-s3-en.question-te.oxidation-states-trend-3","payload":{"stem":"Arrange the following compounds in ascending order according to the oxidation state of the transition metal: $\\ce{CrO3}$, $\\ce{Cu2O}$, $\\ce{VO2}$, $\\ce{Ti2O3}$ (O = −2)","tags":["exam-style","arrange","book_ref:Ch.1 oxidation-states table, p.8 (compounds)"],"type":"order","bloom":"apply","answer":["cu2o","ti2o3","vo2","cro3"],"choices":[{"id":"cro3","text":"$\\ce{CrO3}$"},{"id":"cu2o","text":"$\\ce{Cu2O}$"},{"id":"vo2","text":"$\\ce{VO2}$"},{"id":"ti2o3","text":"$\\ce{Ti2O3}$"}],"book_ref":"Ch.1 oxidation-states table, p.8 (compounds)","difficulty":3,"concept_ids":["te.oxidation-states-trend","pt.oxidation-number"],"est_seconds":90},"layer":{"choices":{"vo2":{"why":"Two O atoms give −4, with one V atom, so V is +4.","feedback":"Misconception: Ranking by the number of O atoms without calculating."},"cro3":{"why":"Three O atoms give −6, and there is one Cr atom, so Cr is +6.","feedback":"Misconception: Ranking by the number of O atoms without calculating."},"cu2o":{"why":"The 2 counts copper atoms: they share oxygen's −2, so each Cu is +1.","feedback":"Misconception: The subscript of the metal is its oxidation state."},"ti2o3":{"why":"Two Ti atoms share +6, so each Ti is +3, not +6.","feedback":"Misconception: The whole positive total belongs to one metal atom."}},"explanation":"Use the sum-to-zero rule with O = −2. $\\ce{Cu2O}$: 2x − 2 = 0, so x = +1. $\\ce{Ti2O3}$: 2x − 6 = 0, so x = +3. $\\ce{VO2}$: x − 4 = 0, so x = +4. $\\ce{CrO3}$: x − 6 = 0, so x = +6. Order: $\\ce{Cu2O}$ < $\\ce{Ti2O3}$ < $\\ce{VO2}$ < $\\ce{CrO3}$. Most likely wrong order: ranking by the number of O atoms. That ignores how many metal atoms share the oxygen."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"vo2":{"why":"ذرتين O بيدوا −4، ومعاهم ذرة V واحدة، فالـ V لازم يبقى +4 عشان يلغي ده.","feedback":"الفكرة الغلط: إنك ترتّب حسب عدد ذرات الـ O من غير ما تحسب."},"cro3":{"why":"تلات ذرات O بيدوا −6، ومعاهم ذرة Cr واحدة، فالـ Cr هنا +6.","feedback":"الفكرة الغلط: إنك ترتّب حسب عدد ذرات الـ O من غير ما تحسب."},"cu2o":{"why":"الـ 2 ده عدد ذرات الـ copper، والـ −2 بتاعة الـ oxygen بتتقسم عليهم، فكل ذرة copper بتبقى +1.","feedback":"الفكرة الغلط: إن الرقم الصغير اللي جنب الـ metal هو الـ oxidation state بتاعه."},"ti2o3":{"why":"ذرتين الـ Ti بيتقسموا الـ +6، فكل ذرة Ti بتبقى +3، مش +6.","feedback":"الفكرة الغلط: إن المجموع الموجب كله بتاع ذرة metal واحدة."}},"explanation":"استخدم قاعدة إن المجموع بيساوي صفر، والـ O = −2. $\\ce{Cu2O}$: 2x − 2 = 0، يعني x = +1. $\\ce{Ti2O3}$: 2x − 6 = 0، يعني x = +3. $\\ce{VO2}$: x − 4 = 0، يعني x = +4. $\\ce{CrO3}$: x − 6 = 0، يعني x = +6. الترتيب: $\\ce{Cu2O}$ < $\\ce{Ti2O3}$ < $\\ce{VO2}$ < $\\ce{CrO3}$. أشهر غلطة: إنك ترتّب حسب عدد ذرات الـ O، وده بيتجاهل كام ذرة metal بيتقسموا الـ oxygen."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":56,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.multiple-oxidation-states-3","kind":"question","version":1,"ord":230,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.multiple-oxidation-states","concepts":[{"concept_id":"te.multiple-oxidation-states","role":"primary"}],"title":"chem-s3-en.question-te.multiple-oxidation-states-3","payload":{"stem":"Compare: classify each description as belonging to the main transition metals or to the representative metals.","tags":["exam-style","compare","classify","book_ref:Ch.1 point 5, p.10"],"type":"classify","bloom":"understand","answer":{"tm":["s1","s3","s5"],"rep":["s2","s4"]},"choices":[{"id":"s1","text":"Show several oxidation states in their compounds"},{"id":"s2","text":"Usually show one oxidation state in their compounds"},{"id":"s3","text":"Lose electrons from two sublevels close in energy (4s and 3d)"},{"id":"s4","text":"A big jump in ionization energy follows the loss of the outer electrons"},{"id":"s5","text":"Successive ionization energies rise gradually, with no big jump"}],"book_ref":"Ch.1 point 5, p.10","categories":[{"id":"tm","label":"Main transition metals"},{"id":"rep","label":"Representative metals"}],"difficulty":2,"concept_ids":["te.multiple-oxidation-states"],"est_seconds":90},"layer":{"choices":{"s1":{"why":"The book lists several states for V and Mn, while Na shows one.","feedback":"Misconception: Representative metals show several states because they have many electrons."},"s2":{"why":"Sodium and magnesium usually show one oxidation state, while V and Mn show several.","feedback":"Misconception: Transition metals keep one fixed oxidation state."},"s3":{"why":"V and Mn have electrons in both 4s and 3d to lose, and these sublevels are close in energy.","feedback":"Misconception: Representative metals lose electrons from 4s and 3d."},"s4":{"why":"The big jump appears in sodium's values: once its outer electron goes, the next electron must leave a stable inner level.","feedback":"Misconception: A huge jump appears right after the 4s electrons of a transition metal."},"s5":{"why":"Vanadium's values (648, 1346, 2858 …) climb step by step with no big jump, because its 4s and 3d sublevels are close in energy.","feedback":"Misconception: Representative metals show a gradual rise."}},"explanation":"Representative metals, such as Na and Mg, usually show one oxidation state. Once their outer electrons go, the next electron must leave a stable inner level. So a big jump in ionization energy appears. Main transition metals lose 4s and 3d electrons in sequence. These sublevels are close in energy, so the energies rise gradually. That is why they show several oxidation states."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"s1":{"why":"الكتاب بيذكر كذا state للـ V والـ Mn، أما الـ Na فليه state واحدة؛ الوصف ده بيطابق عناصر زي الـ V والـ Mn.","feedback":"الفكرة الغلط: إن الـ representative metals بتدّي كذا state عشان عندها electrons كتير."},"s2":{"why":"الـ sodium والـ magnesium كل واحد فيهم عادةً بيدّي state واحدة؛ الوصف ده بيطابقهم.","feedback":"الفكرة الغلط: إن الـ transition metals بتفضل على oxidation state واحدة ثابتة."},"s3":{"why":"الـ metals زي الـ V والـ Mn هي اللي عندها electrons في الـ 4s والـ 3d الاتنين تقدر تفقدها.","feedback":"الفكرة الغلط: إن الـ representative metals بتفقد electrons من الـ 4s والـ 3d."},"s4":{"why":"القفزة الكبيرة بتظهر في قيم الـ sodium، مش في قيم الـ vanadium.","feedback":"الفكرة الغلط: إن فيه قفزة كبيرة بتظهر على طول بعد الـ 4s electrons بتوع الـ transition metal."},"s5":{"why":"قيم الـ vanadium: 648، 1346، 2858 … بتطلع خطوة خطوة من غير قفزة كبيرة؛ الوصف ده بيطابق الـ vanadium.","feedback":"الفكرة الغلط: إن الـ representative metals بتزيد قيمها تدريجيًا."}},"explanation":"الـ representative metals، زي الـ Na والـ Mg، عادةً بتدّي oxidation state واحدة. أول ما الـ electrons الخارجية بتاعتها تمشي، الـ electron اللي بعده لازم يطلع من مستوى داخلي مستقر. فبتظهر قفزة كبيرة في الـ ionization energy. أما الـ main transition metals فبتفقد الـ 4s والـ 3d electrons بالتتابع. والـ sublevels دول قريبين من بعض في الطاقة، فالطاقات بتزيد تدريجيًا. وعشان كده بتدّي كذا oxidation state."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":57,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.definition-3","kind":"question","version":2,"ord":231,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.definition","concepts":[{"concept_id":"te.definition","role":"primary"}],"title":"chem-s3-en.question-te.definition-3","payload":{"stem":"Consider the following statements:\n(I) An element can be a transition element even if one of its ions has an empty d sublevel.\n(II) Every element of the d-block is a transition element.\n(III) An element whose atom has a completely filled d sublevel can still be a transition element.\nWhich of these statements is/are correct?","tags":["exam-style","statements-I-II-III","book_ref:Ch.1 point 6, p.10; Exercises 1-2, pp.10-11"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"I and III only","correct":true},{"id":"b","text":"I only","correct":false},{"id":"c","text":"I, II and III","correct":false,"misconception_id":"te.definition.mc1"},{"id":"d","text":"III only","correct":false,"misconception_id":"te.definition.mc2"}],"book_ref":"Ch.1 point 6, p.10; Exercises 1-2, pp.10-11","difficulty":3,"concept_ids":["te.definition"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: one incomplete d, in the atom or in one oxidation state, is enough."},"b":{"why":"This leaves out (III), which is also true: the definition also checks the oxidation states, and copper's atom is $3d^{10}$ while $\\ce{Cu^{2+}}$ is $3d^9$.","feedback":"Misconception: An element with a d¹⁰ atom can never be a transition element."},"c":{"why":"(II) is false: zinc is in the d-block, but its d sublevel is complete in the atom and in its ion, so it is not a transition element.","feedback":"Misconception: Every d-block element is a transition element."},"d":{"why":"This leaves out (I), which is also true: the scandium atom is $3d^1$, incomplete, so scandium is a transition element though $\\ce{Sc^{3+}}$ has no d electrons.","feedback":"Misconception: Sc is not a transition element because Sc³⁺ is d⁰."}},"explanation":"(I) Correct. Scandium's atom is $3d^1$, so it is a transition element, though $\\ce{Sc^{3+}}$ is $3d^0$. (II) Wrong. Zn, Cd and Hg are in the d-block, but they are $d^{10}$ in the atom and the ion. (III) Correct. Copper's atom is $3d^{10}$, but $\\ce{Cu^{2+}}$ is $3d^9$, which is incomplete. The definition checks the atom or one of its oxidation states. Answer: I and III only."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: يكفي d واحد مش مكتمل، في الذرة أو في حالة واحدة من الـ oxidation states."},"b":{"why":"كده إنت سبت (III)، وهي صح كمان: التعريف بيبص كمان على الـ oxidation states، وذرة الـ copper $3d^{10}$ بينما الـ $\\ce{Cu^{2+}}$ بيبقى $3d^9$.","feedback":"الفكرة الغلط: إن العنصر اللي ذرته d¹⁰ عمره ما يبقى transition element."},"c":{"why":"(II) غلط: الـ zinc موجود في الـ d-block، لكن الـ d sublevel بتاعه مكتمل في الذرة وفي الـ ion، فهو مش transition element.","feedback":"الفكرة الغلط: إن أي عنصر في الـ d-block يبقى transition element."},"d":{"why":"كده إنت سبت (I)، وهي صح كمان: ذرة الـ scandium $3d^1$، incomplete، فالـ scandium transition element رغم إن الـ $\\ce{Sc^{3+}}$ مفيهوش d electrons.","feedback":"الفكرة الغلط: إن الـ Sc مش transition element عشان الـ Sc³⁺ يبقى d⁰."}},"explanation":"(I) صح. ذرة الـ scandium $3d^1$، فهو transition element، حتى لو الـ $\\ce{Sc^{3+}}$ يبقى $3d^0$. (II) غلط. الـ Zn والـ Cd والـ Hg في الـ d-block، لكنهم $d^{10}$ في الذرة وفي الـ ion. (III) صح. ذرة الـ copper $3d^{10}$، لكن الـ $\\ce{Cu^{2+}}$ بيبقى $3d^9$، يعني مش مكتمل. التعريف بيبص على الذرة أو على حالة من الـ oxidation states بتاعتها. الإجابة: I and III only."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":58,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.definition","section_title":"The transition element (definition)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","The transition element (definition)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":11,"page_to":11,"section_key":"ch1.config.ex2","section_title":"Zinc, cadmium and mercury","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Zinc, cadmium and mercury"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.definition-applied-3","kind":"question","version":1,"ord":232,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.definition-applied","concepts":[{"concept_id":"te.definition-applied","role":"primary"},{"concept_id":"te.definition","role":"secondary"}],"title":"chem-s3-en.question-te.definition-applied-3","payload":{"stem":"Classify each element, using the configurations given, as a transition element or not a transition element.","tags":["exam-style","classify","book_ref:Ch.1 point 6 + Exercises 1-2, pp.10-11"],"type":"classify","bloom":"apply","answer":{"te":["ni","la","cu"],"nte":["hg","in"]},"choices":[{"id":"ni","text":"$_{28}$Ni: atom [Ar] $4s^2\\,3d^8$"},{"id":"la","text":"$_{57}$La: atom [Xe] $6s^2\\,5d^1$; $\\ce{La^{3+}}$: [Xe]"},{"id":"cu","text":"$_{29}$Cu: atom [Ar] $4s^1\\,3d^{10}$; $\\ce{Cu+}$: [Ar] $3d^{10}$; $\\ce{Cu^{2+}}$: [Ar] $3d^9$"},{"id":"hg","text":"$_{80}$Hg: atom [Xe] $4f^{14}\\,6s^2\\,5d^{10}$; $\\ce{Hg^{2+}}$: [Xe] $4f^{14}\\,5d^{10}$","misconception_id":"te.definition.mc1"},{"id":"in","text":"$_{49}$In: atom [Kr] $4d^{10}\\,5s^2\\,5p^1$; $\\ce{In^{3+}}$: [Kr] $4d^{10}$"}],"book_ref":"Ch.1 point 6 + Exercises 1-2, pp.10-11","categories":[{"id":"te","label":"Transition element"},{"id":"nte","label":"Not a transition element"}],"difficulty":3,"concept_ids":["te.definition-applied","te.definition"],"est_seconds":120},"layer":{"choices":{"cu":{"why":"The atom and $\\ce{Cu+}$ are $3d^{10}$, but $\\ce{Cu^{2+}}$ is $3d^9$, incomplete. One such oxidation state is enough.","feedback":"Misconception: Cu is not a transition element because its atom is d¹⁰."},"hg":{"why":"Hg is $5d^{10}$ in the atom and in $\\ce{Hg^{2+}}$: its d sublevel is complete in both, so being in the d-block is not enough.","feedback":"Misconception: Every d-block element is a transition element."},"in":{"why":"The d orbitals contain electrons, but they are complete in both the atom and the ion.","feedback":"Misconception: Any element with electrons in d orbitals is a transition element."},"la":{"why":"The ion has no d electrons, but the atom holds one electron in 5d, an incomplete sublevel.","feedback":"Misconception: An element whose only ion is d⁰ is not a transition element."},"ni":{"why":"The atom holds 8 of the 10 possible 3d electrons, so its 3d is incomplete.","feedback":"Misconception: Only elements with d¹⁰ or d⁵ count as transition elements."}},"explanation":"Apply two tests: the atom first, then the oxidation states. Ni: the atom is $3d^8$, incomplete, so it is a transition element. La: the atom is $5d^1$, incomplete, so it is one, though $\\ce{La^{3+}}$ has no d electrons. Cu: the atom is $3d^{10}$, but $\\ce{Cu^{2+}}$ is $3d^9$, incomplete, so it is one. Hg: $5d^{10}$ in the atom and in $\\ce{Hg^{2+}}$, so it is not. In: $4d^{10}$ in the atom and in $\\ce{In^{3+}}$, so it is not."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"cu":{"why":"الذرة والـ $\\ce{Cu+}$ الاتنين $3d^{10}$، لكن الـ $\\ce{Cu^{2+}}$ بيبقى $3d^9$، يعني incomplete. وحالة واحدة زي دي كفاية.","feedback":"الفكرة الغلط: إن الـ Cu مش transition element عشان ذرته d¹⁰."},"hg":{"why":"الـ Hg هو $5d^{10}$ في الذرة وفي الـ $\\ce{Hg^{2+}}$: الـ d sublevel بتاعه مكتمل في الاتنين، فوجوده في الـ d-block مش كفاية.","feedback":"الفكرة الغلط: إن أي عنصر في الـ d-block يبقى transition element."},"in":{"why":"الـ d orbitals فيها electrons فعلًا، لكنها مكتملة في الذرة وفي الـ ion الاتنين.","feedback":"الفكرة الغلط: إن أي عنصر فيه electrons في الـ d orbitals يبقى transition element."},"la":{"why":"الـ ion مفيهوش d electrons، لكن الذرة شايلة electron واحد في الـ 5d، وده sublevel مش مكتمل.","feedback":"الفكرة الغلط: إن العنصر اللي الـ ion الوحيد بتاعه d⁰ مش transition element."},"ni":{"why":"الذرة فيها 8 من الـ 10 3d electrons الممكنين، يعني الـ 3d بتاعها incomplete.","feedback":"الفكرة الغلط: إن العناصر اللي d¹⁰ أو d⁵ تحديدًا هي اللي تتحسب transition elements."}},"explanation":"طبّق اختبارين: الذرة الأول، وبعدين الـ oxidation states. الـ Ni: الذرة $3d^8$، incomplete، يبقى transition element. الـ La: الذرة $5d^1$، incomplete، يبقى transition element، رغم إن الـ $\\ce{La^{3+}}$ مفيهوش d electrons. الـ Cu: الذرة $3d^{10}$، لكن الـ $\\ce{Cu^{2+}}$ هو $3d^9$، incomplete، يبقى transition element. الـ Hg: $5d^{10}$ في الذرة وفي الـ $\\ce{Hg^{2+}}$، يبقى مش transition element. الـ In: $4d^{10}$ في الذرة وفي الـ $\\ce{In^{3+}}$، يبقى مش transition element."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":59,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.definition","section_title":"The transition element (definition)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","The transition element (definition)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":11,"page_to":11,"section_key":"ch1.config.ex2","section_title":"Zinc, cadmium and mercury","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Zinc, cadmium and mercury"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.electron-configuration-4","kind":"question","version":1,"ord":233,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.electron-configuration","concepts":[{"concept_id":"te.electron-configuration","role":"primary"},{"concept_id":"atom.hund-rule","role":"secondary"}],"title":"chem-s3-en.question-te.electron-configuration-4","payload":{"stem":"Consider the following statements about atoms of the first transition series:\n(I) In the $_{25}$Mn atom, each of the five 3d orbitals contains one electron.\n(II) The $_{26}$Fe atom has more unpaired 3d electrons than the $_{25}$Mn atom.\n(III) The $_{28}$Ni atom has two unpaired electrons in its 3d sublevel.\nWhich of these statements is/are correct?","tags":["exam-style","statements-I-II-III","book_ref:Ch.1 p.8 table + point 1"],"type":"mcq","bloom":"analyze","choices":[{"id":"a","text":"I and III only","correct":true},{"id":"b","text":"I and II only","correct":false},{"id":"c","text":"II and III only","correct":false},{"id":"d","text":"I, II and III","correct":false}],"difficulty":4,"concept_ids":["te.electron-configuration","atom.hund-rule"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Correct! Mn 3d⁵ has five single electrons, Fe 3d⁶ has only 4 unpaired (fewer than Mn), and Ni 3d⁸ has 2 unpaired."},"b":{"why":"(II) is wrong and (III) is correct: by Hund's rule Fe 3d⁶ has one pair and 4 unpaired electrons, fewer than Mn's 5, and Ni 3d⁸ has three pairs and 2 unpaired electrons.","feedback":"Misconception: More 3d electrons means more unpaired electrons; Ni's 3d⁸ paired up early (4 pairs, 0 unpaired)."},"c":{"why":"(I) is correct: Hund's rule spreads Mn's five 3d electrons one into each of the five orbitals. And (II) is false: Fe 3d⁶ has 4 unpaired electrons, fewer than Mn's 5.","feedback":"Misconception: Pairing in Mn's 3d before all five orbitals are singly occupied; more 3d electrons = more unpaired."},"d":{"why":"(I) and (III) are fine. But (II) is false: Fe's sixth 3d electron pairs up, so Fe has 4 unpaired 3d electrons, fewer than Mn's 5.","feedback":"Misconception: More 3d electrons means more unpaired electrons (accepts II)."}},"explanation":"Write the configuration and draw the 3d boxes for each atom. Mn: [Ar] 4s² 3d⁵ → [↑] [↑] [↑] [↑] [↑] = 5 unpaired, so (I) is correct. Fe: [Ar] 4s² 3d⁶ → [↑↓] [↑] [↑] [↑] [↑] = 4 unpaired, which is fewer than Mn, so (II) is wrong. Ni: [Ar] 4s² 3d⁸ → [↑↓] [↑↓] [↑↓] [↑] [↑] = 2 unpaired, so (III) is correct. Answer: I and III only. The idea (from the book): the 3d orbitals are filled by a single electron in each orbital till manganese ($3d^5$), and after manganese pairing takes place till zinc ($3d^{10}$) (Hund's rule). So the number of unpaired electrons rises up to Mn and then falls."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ Mn 3d⁵ فيه خمس electrons فرادى، والـ Fe 3d⁶ فيه 4 unpaired تحديدًا (أقل من الـ Mn)، والـ Ni 3d⁸ فيه 2 unpaired."},"b":{"why":"إنت قبلت (II) ورفضت (III). بالـ Hund's rule في خمس مربعات، الـ Fe 3d⁶ فيه 4 unpaired، أقل من الـ 5 بتوع الـ Mn، والـ Ni 3d⁸ فيه 2 unpaired، فـ(II) غلط و(III) صح.","feedback":"الفكرة الغلط: إن electrons أكتر في الـ 3d يعني unpaired electrons أكتر، وإن الـ 3d⁸ بتاع الـ Ni عمل أزواج بدري (4 أزواج، 0 unpaired)."},"c":{"why":"(I) صح: الـ Hund's rule بيوزّع الـ 5 electrons بتوع الـ 3d في الـ Mn واحد في كل orbital من الخمسة. وكمان (II) غلط: الـ Fe 3d⁶ فيه 4 unpaired، أقل من الـ 5 بتوع الـ Mn.","feedback":"الفكرة الغلط: الأزواج في الـ 3d بتاع الـ Mn قبل ما الـ 5 orbitals ياخدوا electron واحد واحد؛ وإن electrons أكتر في الـ 3d = unpaired أكتر."},"d":{"why":"الـ (I) والـ (III) تمام. لكن (II) غلط: الـ electron السادس في الـ 3d بتاع الـ Fe بيعمل زوج، فالـ Fe فيه 4 unpaired، أقل من الـ 5 بتوع الـ Mn.","feedback":"الفكرة الغلط: إن electrons أكتر في الـ 3d يعني unpaired electrons أكتر (قبول II)."}},"explanation":"اكتب الـ configuration وارسم مربعات الـ 3d لكل ذرة. الـ Mn: [Ar] 4s² 3d⁵ → [↑] [↑] [↑] [↑] [↑] = 5 unpaired، يبقى (I) صح. الـ Fe: [Ar] 4s² 3d⁶ → [↑↓] [↑] [↑] [↑] [↑] = 4 unpaired، وده أقل من الـ Mn، يبقى (II) غلط. الـ Ni: [Ar] 4s² 3d⁸ → [↑↓] [↑↓] [↑↓] [↑] [↑] = 2 unpaired، يبقى (III) صح. الإجابة: I and III only. الفكرة (من الكتاب): the 3d orbitals are filled by a single electron in each orbital till manganese ($3d^5$), and after manganese pairing takes place till zinc ($3d^{10}$) (Hund's rule). عشان كده عدد الـ unpaired electrons بيزيد لحد الـ Mn وبعدين بيقل."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":60,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.cr-cu-anomaly-4","kind":"question","version":1,"ord":234,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.cr-cu-anomaly","concepts":[{"concept_id":"te.cr-cu-anomaly","role":"primary"},{"concept_id":"te.electron-configuration","role":"secondary"}],"title":"chem-s3-en.question-te.cr-cu-anomaly-4","payload":{"stem":"A student wrote the configurations shown in the table. Which one is wrong?","tags":["exam-style","data-reading","book_ref:Ch.1 table + point 2, pp.8-9"],"type":"mcq","bloom":"apply","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["$_{23}$V","[Ar] $4s^2\\,3d^3$"],["$_{24}$Cr","[Ar] $4s^2\\,3d^4$"],["$_{25}$Mn","[Ar] $4s^2\\,3d^5$"],["$_{29}$Cu","[Ar] $4s^1\\,3d^{10}$"]],"caption":"A student's configurations","headers":["Atom","Student's configuration"]},"children":[]}}},"choices":[{"id":"a","text":"$_{23}$V","correct":false},{"id":"b","text":"$_{24}$Cr","correct":true},{"id":"c","text":"$_{25}$Mn","correct":false},{"id":"d","text":"$_{29}$Cu","correct":false}],"book_ref":"Ch.1 table + point 2, pp.8-9","difficulty":4,"concept_ids":["te.cr-cu-anomaly","te.electron-configuration"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Moving one 4s electron would leave V's 3d with 4 electrons, neither half filled nor filled, so V follows the general pattern and is written correctly.","feedback":"Misconception: V moves an electron too and should be 4s¹ 3d⁴."},"b":{"why":"Right: the book writes Cr as [Ar] 4s¹ 3d⁵, with both sublevels half filled."},"c":{"why":"Mn's 3d already holds 5 electrons (half filled), so moving a 4s electron gives no extra stability; its configuration is correct.","feedback":"Misconception: Mn also promotes an electron: [Ar] 4s¹ 3d⁶."},"d":{"why":"Copper is written correctly: the book calls Cr and Cu anomalous and writes Cu with one electron in 4s and ten in 3d.","feedback":"Misconception: Cu follows the general pattern: [Ar] 4s² 3d⁹."}},"explanation":"Check each atom against the book. V: [Ar] $4s^2\\,3d^3$ follows the pattern, so it is correct. Mn: [Ar] $4s^2\\,3d^5$ already has a half-filled 3d, so it is correct. Cu: [Ar] $4s^1\\,3d^{10}$ is the book's abnormal configuration, so it is correct. Cr is the error: the book writes [Ar] $4s^1\\,3d^5$. In the first series, only Cr and Cu break the pattern."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"لو الـ V نقل electron واحد من الـ 4s، الـ 3d بتاعه هيبقى فيه 4 electrons، لا half filled ولا filled، فالـ V ماشي على القاعدة العامة ومكتوب صح.","feedback":"الفكرة الغلط: إن الـ V هو كمان بينقل electron، والمفروض يبقى 4s¹ 3d⁴."},"b":{"why":"صح: الكتاب بيكتب الـ Cr كـ [Ar] 4s¹ 3d⁵، والـ sublevels الاتنين half filled."},"c":{"why":"الـ 3d بتاع الـ Mn فيه 5 electrons أصلًا (half filled)، فنقل electron من الـ 4s مش هيدّيه أي extra stability، والتوزيع بتاعه صح.","feedback":"الفكرة الغلط: إن الـ Mn كمان بينقل electron: [Ar] 4s¹ 3d⁶."},"d":{"why":"الـ copper مكتوب صح: الكتاب بيقول على الـ Cr والـ Cu إنهم anomalous، وبيكتب الـ Cu بـ electron واحد في الـ 4s وعشرة في الـ 3d.","feedback":"الفكرة الغلط: إن الـ Cu ماشي على القاعدة العامة: [Ar] 4s² 3d⁹."}},"explanation":"راجع كل ذرة على الكتاب. الـ V: [Ar] $4s^2\\,3d^3$ ماشي على القاعدة، يبقى صح. الـ Mn: [Ar] $4s^2\\,3d^5$ الـ 3d بتاعه half filled أصلًا، يبقى صح. الـ Cu: [Ar] $4s^1\\,3d^{10}$ ده الـ abnormal configuration اللي في الكتاب، يبقى صح. الغلط في الـ Cr: الكتاب بيكتبه [Ar] $4s^1\\,3d^5$. وفي السلسلة الأولى مفيش غير الـ Cr والـ Cu اللي بيكسروا القاعدة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":61,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.ion-configuration-4","kind":"question","version":1,"ord":235,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.ion-configuration","concepts":[{"concept_id":"te.ion-configuration","role":"primary"}],"title":"chem-s3-en.question-te.ion-configuration-4","payload":{"stem":"Give reasons: Most elements of the first transition series show the oxidation state (+2).","tags":["exam-style","give-reasons","book_ref:Ch.1 point 3, p.9"],"type":"short","bloom":"understand","answer":"Key points: (1) When the atom is oxidized, it loses its 4s electrons first, because 4s is in the outermost level (n = 4). (2) Losing the two 4s electrons gives the oxidation state (+2). (3) Cr and Cu (4s¹) lose their 4s electron and one 3d electron. (4) Scandium is the exception: it shows only (+3). (5) In higher oxidation states, 3d electrons are lost in sequence.","book_ref":"Ch.1 point 3, p.9","difficulty":2,"concept_ids":["te.ion-configuration"],"est_seconds":90},"layer":{"explanation":"Most atoms of the series end with $4s^2$. The 4s electrons are in the outermost level (n = 4). So when the atom is oxidized, they are lost first. Losing these two electrons gives the oxidation state (+2). Example: Mn [Ar] $4s^2\\,3d^5$ → $\\ce{Mn^{2+}}$ [Ar] $3d^5$. Cr and Cu have only $4s^1$, so they also lose one 3d electron. Scandium is the exception: the book gives it only (+3). Key words: lose the 4s electrons first, oxidation state (+2), except scandium. Most likely wrong answer: 'they lose two 3d electrons'. Apart from Cr and Cu, 3d electrons leave only in the higher states."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"أغلب ذرات السلسلة بتنتهي بـ $4s^2$. والـ 4s electrons موجودين في المستوى الخارجي (n = 4)، فلما الذرة تتأكسد بيطلعوا هما الأول. وفقد الاتنين electrons دول بيدّي الـ oxidation state (+2). مثال: Mn [Ar] $4s^2\\,3d^5$ ← $\\ce{Mn^{2+}}$ [Ar] $3d^5$. الـ Cr والـ Cu عندهم $4s^1$ لوحده، فبيفقدوا كمان 3d electron واحد. والـ scandium هو الاستثناء: الكتاب بيدّيله (+3) تحديدًا. الكلمات المهمة: lose the 4s electrons first، oxidation state (+2)، except scandium. أشهر إجابة غلط: «بيفقدوا اتنين 3d electrons». وما عدا حالة الـ Cr والـ Cu، الـ 3d electrons مش بتطلع غير في الحالات الأعلى."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":62,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.fe2-fe3-mn2-stability-4","kind":"question","version":1,"ord":236,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.fe2-fe3-mn2-stability","concepts":[{"concept_id":"te.fe2-fe3-mn2-stability","role":"primary"},{"concept_id":"pt.oxidation-number","role":"secondary"},{"concept_id":"te.ion-configuration","role":"secondary"}],"title":"chem-s3-en.question-te.fe2-fe3-mn2-stability-4","payload":{"stem":"In which pair of compounds do the metal ions have the same number of unpaired electrons? ($_{25}$Mn, $_{26}$Fe)","tags":["exam-style","unpaired-electrons","book_ref:Ch.1 worked exercise, p.9; oxidation-states table, p.8"],"type":"mcq","bloom":"analyze","choices":[{"id":"a","text":"$\\ce{MnSO4}$ and $\\ce{Fe2O3}$","correct":true},{"id":"b","text":"$\\ce{FeO}$ and $\\ce{MnO}$","correct":false},{"id":"c","text":"$\\ce{Mn2O3}$ and $\\ce{Fe2O3}$","correct":false},{"id":"d","text":"$\\ce{MnO2}$ and $\\ce{Fe2O3}$","correct":false}],"book_ref":"Ch.1 worked exercise, p.9; oxidation-states table, p.8","difficulty":4,"concept_ids":["te.fe2-fe3-mn2-stability","te.ion-configuration","pt.oxidation-number"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Right: Mn²⁺ and Fe³⁺ are both 3d⁵, with 5 unpaired electrons each."},"b":{"why":"Both ions are 2+, but Fe and Mn start with different numbers of 3d electrons, so Fe²⁺ (3d⁶) has 4 unpaired and Mn²⁺ (3d⁵) has 5.","feedback":"Misconception: Ions with the same charge have the same number of unpaired electrons."},"c":{"why":"Same formula type and same charge, but Mn³⁺ is 3d⁴ with 4 unpaired electrons, while Fe³⁺ is 3d⁵ with 5.","feedback":"Misconception: Compounds with the same formula type have the same ion configuration."},"d":{"why":"Manganese is +4 in $\\ce{MnO2}$, so its ion is 3d³ with 3 unpaired electrons, not the atom's $3d^5$.","feedback":"Misconception: Counting the unpaired electrons of the atom instead of the ion in the compound."}},"explanation":"Step 1: oxidation states. $\\ce{MnSO4}$: Mn +2. $\\ce{Fe2O3}$: Fe +3. $\\ce{FeO}$: Fe +2. $\\ce{MnO}$: Mn +2. $\\ce{Mn2O3}$: Mn +3. $\\ce{MnO2}$: Mn +4. Step 2: the ions, with 4s lost first. $\\ce{Mn^{2+}}$ $3d^5$, $\\ce{Fe^{3+}}$ $3d^5$, $\\ce{Fe^{2+}}$ $3d^6$, $\\ce{Mn^{3+}}$ $3d^4$, $\\ce{Mn^{4+}}$ $3d^3$. Step 3: Hund's rule. $3d^5$ → 5, $3d^6$ → 4, $3d^4$ → 4, $3d^3$ → 3. Only $\\ce{MnSO4}$ and $\\ce{Fe2O3}$ match, with 5 each. Both ions have the half-filled $3d^5$ sublevel."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ Mn²⁺ والـ Fe³⁺ الاتنين 3d⁵، وكل واحد فيهم فيه 5 unpaired electrons."},"b":{"why":"الاتنين 2+، لكن الـ Fe والـ Mn بيبدأوا بعدد 3d electrons مختلف، فالـ Fe²⁺ (3d⁶) فيه 4 unpaired والـ Mn²⁺ (3d⁵) فيه 5.","feedback":"الفكرة الغلط: إن الـ ions اللي ليها نفس الـ charge فيها نفس عدد الـ unpaired electrons."},"c":{"why":"نفس نوع الصيغة ونفس الـ charge، لكن الـ manganese بـ +3 بيفضل معاه أربعة 3d electrons كلهم unpaired، والـ iron بـ +3 بيفضل معاه خمسة، فالعدد مختلف (4 و5).","feedback":"الفكرة الغلط: إن الـ compounds اللي ليها نفس نوع الصيغة فيها نفس تركيب الـ ion."},"d":{"why":"الـ manganese بـ +4 في الـ $\\ce{MnO2}$، فالـ ion بتاعه 3d³ وفيه 3 unpaired electrons، مش الـ $3d^5$ بتاع الذرة.","feedback":"الفكرة الغلط: إنك تعدّ الـ unpaired electrons بتوع الـ atom بدل الـ ion اللي في الـ compound."}},"explanation":"الخطوة 1: الـ oxidation states. $\\ce{MnSO4}$: Mn +2. $\\ce{Fe2O3}$: Fe +3. $\\ce{FeO}$: Fe +2. $\\ce{MnO}$: Mn +2. $\\ce{Mn2O3}$: Mn +3. $\\ce{MnO2}$: Mn +4. الخطوة 2: الـ ions، والـ 4s بيخرج الأول. $\\ce{Mn^{2+}}$ $3d^5$، $\\ce{Fe^{3+}}$ $3d^5$، $\\ce{Fe^{2+}}$ $3d^6$، $\\ce{Mn^{3+}}$ $3d^4$، $\\ce{Mn^{4+}}$ $3d^3$. الخطوة 3: الـ Hund's rule. $3d^5$ → 5، $3d^6$ → 4، $3d^4$ → 4، $3d^3$ → 3. مفيش غير $\\ce{MnSO4}$ و$\\ce{Fe2O3}$ اللي متساويين، 5 في كل واحد. والاتنين الـ ion بتاعهم فيه الـ $3d^5$ sublevel اللي نصه مليان."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":63,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.oxidation-states-trend-4","kind":"question","version":1,"ord":237,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.oxidation-states-trend","concepts":[{"concept_id":"te.oxidation-states-trend","role":"primary"}],"title":"chem-s3-en.question-te.oxidation-states-trend-4","payload":{"stem":"Give reasons: Manganese ($_{25}$Mn) reaches the oxidation state (+7), while zinc ($_{30}$Zn) shows only (+2).","tags":["exam-style","give-reasons","book_ref:Ch.1 table + point 4, pp.8-9"],"type":"short","bloom":"understand","answer":"Key points: (1) Mn: [Ar] 4s² 3d⁵; it can lose all seven 4s and 3d electrons, giving (+7). (2) Mn is in group VIIB, and the maximum oxidation state does not exceed the group number. (3) Zn: [Ar] 4s² 3d¹⁰; it loses only its two 4s electrons, giving Zn²⁺ [Ar] 3d¹⁰ (filled 3d). (4) Zn is in group IIB, so its maximum is (+2). (5) Oxidation states increase from Sc to Mn (+7), then decrease to (+2) in Zn.","book_ref":"Ch.1 table + point 4, pp.8-9","difficulty":3,"concept_ids":["te.oxidation-states-trend"],"est_seconds":120},"layer":{"explanation":"Mn is [Ar] $4s^2\\,3d^5$. Losing all seven 4s and 3d electrons gives (+7), equal to its group number (VIIB). Zn is [Ar] $4s^2\\,3d^{10}$. It loses only its two 4s electrons. $\\ce{Zn^{2+}}$ is [Ar] $3d^{10}$, with a filled 3d. Zinc is in group IIB, and the maximum does not exceed the group number. Key words: oxidation states increase from scandium to manganese (+7), then decrease to (+2) in zinc. Most likely wrong answer: 'Zn has more electrons, so it reaches a higher state'. Zinc's 3d electrons are not lost."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ Mn هو [Ar] $4s^2\\,3d^5$. لما يفقد الـ 7 electrons اللي في الـ 4s والـ 3d كلهم بيوصل لـ (+7)، وده بيساوي رقم الـ group بتاعه (VIIB). أما الـ Zn فهو [Ar] $4s^2\\,3d^{10}$، وبيفقد الـ 2 electrons بتوع الـ 4s تحديدًا. فالـ $\\ce{Zn^{2+}}$ بيبقى [Ar] $3d^{10}$، والـ 3d مليان. والـ zinc في group IIB، وأعلى oxidation state مابيعديش رقم الـ group. الكلمات المفتاحية: الـ oxidation states بتزيد من الـ scandium لحد الـ manganese (+7)، وبعدين تقل لحد (+2) في الـ zinc. أشهر إجابة غلط: «الـ Zn عنده electrons أكتر، فيوصل لـ state أعلى». لأ، الـ 3d electrons بتوع الـ zinc مابيتفقدوش."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":64,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.definition-applied-4","kind":"question","version":1,"ord":238,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.definition-applied","concepts":[{"concept_id":"te.definition-applied","role":"primary"},{"concept_id":"te.definition","role":"secondary"},{"concept_id":"te.transition-series","role":"secondary"}],"title":"chem-s3-en.question-te.definition-applied-4","payload":{"stem":"Element X lies in the second transition series. Its only ion, $\\ce{X^{3+}}$, has the configuration [Kr]. Which statement is correct?","tags":["exam-style","two-step","book_ref:Ch.1 point 6, p.10; transition series, pp.4-5"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"X is yttrium ($_{39}$Y), a transition element: its atom is [Kr] $5s^2\\,4d^1$","correct":true},{"id":"b","text":"X is yttrium ($_{39}$Y), not a transition element: $\\ce{X^{3+}}$ has no d electrons","correct":false},{"id":"c","text":"X is strontium ($_{38}$Sr), not a transition element: its atom has no d electrons","correct":false},{"id":"d","text":"X is yttrium ($_{39}$Y), not a transition element: it shows only one oxidation state","correct":false}],"book_ref":"Ch.1 point 6, p.10; transition series, pp.4-5","difficulty":4,"concept_ids":["te.definition-applied","te.definition","te.transition-series"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right: Z = 39, and the atom's 4d¹ is incomplete."},"b":{"why":"Checking only the ion is not enough: the definition also tests the atom, and the Y atom's 4d¹ is incomplete.","feedback":"Misconception: An element whose only ion is d⁰ is not a transition element."},"c":{"why":"A 3+ ion lost three electrons, not two, so Z = 36 + 3, not 36 + 2 = 38 (strontium).","feedback":"Misconception: Adding back only two electrons to find Z."},"d":{"why":"The book's definition says nothing about how many states; it checks the d orbitals, and the Y atom's 4d is incomplete.","feedback":"Misconception: A transition element must show several oxidation states."}},"explanation":"Step 1: [Kr] holds 36 electrons. $\\ce{X^{3+}}$ lost 3, so Z = 36 + 3 = 39: yttrium. Step 2: the Y atom is [Kr] $5s^2\\,4d^1$, the first element of the second series. Its 4d holds one electron, so it is incomplete. So Y is a transition element, though $\\ce{Y^{3+}}$ has no d electrons. One pass, in the atom or in a state, is enough. Scandium is the same case in the first series."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: Z = 39، والـ 4d¹ بتاع الذرة incomplete."},"b":{"why":"إنك تبص على الـ ion لوحده مش كفاية: التعريف بيختبر الذرة كمان، والـ 4d¹ بتاع ذرة الـ Y مش مكتمل.","feedback":"الفكرة الغلط: إن العنصر اللي الـ ion الوحيد بتاعه d⁰ مش transition element."},"c":{"why":"الـ 3+ ion خسر 3 electrons مش 2، يعني Z = 36 + 3، مش 36 + 2 = 38 (الـ strontium).","feedback":"الفكرة الغلط: إنك ترجّع 2 electrons بس عشان تحسب الـ Z."},"d":{"why":"تعريف الكتاب مش بيقول أي حاجة عن عدد الـ states؛ هو بيبص على الـ d orbitals، والـ 4d بتاع ذرة الـ Y مش مكتمل.","feedback":"الفكرة الغلط: إن الـ transition element لازم يكون ليه كذا oxidation state."}},"explanation":"الخطوة 1: الـ [Kr] فيه 36 electrons. الـ $\\ce{X^{3+}}$ خسر 3، يبقى Z = 36 + 3 = 39: يعني yttrium. الخطوة 2: ذرة الـ Y هي [Kr] $5s^2\\,4d^1$، أول عنصر في الـ second series. الـ 4d فيه electron واحد، يعني incomplete. يبقى الـ Y transition element، رغم إن الـ $\\ce{Y^{3+}}$ مفيهوش d electrons. يكفي مرة واحدة يبقى فيها الـ d incomplete، في الذرة أو في state. والـ scandium نفس الحالة في الـ first series."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":65,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.definition","section_title":"The transition element (definition)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","The transition element (definition)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.electron-configuration-5","kind":"question","version":1,"ord":239,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.electron-configuration","concepts":[{"concept_id":"te.electron-configuration","role":"primary"},{"concept_id":"atom.hund-rule","role":"secondary"},{"concept_id":"te.cr-cu-anomaly","role":"secondary"}],"title":"chem-s3-en.question-te.electron-configuration-5","payload":{"stem":"Arrange the following atoms in ascending order according to the total number of unpaired electrons in the atom (4s and 3d together): $_{22}$Ti, $_{24}$Cr, $_{25}$Mn, $_{27}$Co, $_{29}$Cu","tags":["exam-style","arrange","book_ref:Ch.1 p.8 table + point 1","book_ref:Ch.1 p.8 point 2"],"type":"order","bloom":"analyze","answer":["cu","ti","co","mn","cr"],"choices":[{"id":"ti","text":"$_{22}$Ti","correct":true},{"id":"cr","text":"$_{24}$Cr","correct":true},{"id":"mn","text":"$_{25}$Mn","correct":true},{"id":"co","text":"$_{27}$Co","correct":true},{"id":"cu","text":"$_{29}$Cu","correct":true}],"difficulty":5,"concept_ids":["te.electron-configuration","atom.hund-rule","te.cr-cu-anomaly"],"est_seconds":150},"layer":{"choices":{"co":{"why":"Co is [Ar] 4s² 3d⁷: 4s is paired and two 3d orbitals hold pairs, so 3 unpaired. Third place."},"cr":{"why":"Cr is [Ar] 4s¹ 3d⁵: 1 unpaired in 4s + 5 in 3d = 6, the largest number here. Last place."},"cu":{"why":"Cu is [Ar] 4s¹ 3d¹⁰: 3d is full (all paired) and 4s has 1 electron, so 1 unpaired, the smallest. First place."},"mn":{"why":"Mn is [Ar] 4s² 3d⁵: 4s is paired and each 3d orbital has one electron, so 5 unpaired. Fourth place."},"ti":{"why":"Ti is [Ar] 4s² 3d²: 4s is paired and the two 3d electrons sit in separate orbitals (Hund's rule), so 2 unpaired. Second place."}},"explanation":"Write each configuration (book table) and count unpaired electrons in 4s and 3d, using Hund's rule in 3d. Ti: [Ar] 4s² 3d² → 4s paired, 3d [↑] [↑] [ ] [ ] [ ] → 2. Cr: [Ar] 4s¹ 3d⁵ → 1 in 4s + 5 in 3d → 6. Mn: [Ar] 4s² 3d⁵ → 0 + 5 → 5. Co: [Ar] 4s² 3d⁷ → 0 + 3 → 3. Cu: [Ar] 4s¹ 3d¹⁰ → 1 + 0 → 1. Ascending order: Cu (1) < Ti (2) < Co (3) < Mn (5) < Cr (6). Most likely wrong answers: (1) ordering by atomic number (Ti < Cr < Mn < Co < Cu), from the idea \"more electrons = more unpaired electrons\"; after Mn every extra 3d electron pairs up, so the number falls. (2) Writing Cr as [Ar] 4s² 3d⁴ and Cu as [Ar] 4s² 3d⁹ (forgetting the anomaly of chromium and copper), which gives Cr 4 and Cu 1 and puts Cr below Mn. (3) Counting only the 3d electrons, which makes Cr equal to Mn (5 each) and gives Cu 0. Key words: Hund's rule, single electron in each orbital, pairing, half-filled 4s in Cr and Cu."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"co":{"why":"الـ Co هو [Ar] 4s² 3d⁷: الـ 4s أزواج، واتنين orbitals في الـ 3d فيهم أزواج، يبقى 3 unpaired. المركز التالت."},"cr":{"why":"الـ Cr هو [Ar] 4s¹ 3d⁵: 1 unpaired في الـ 4s + 5 في الـ 3d = 6، وده أكبر عدد هنا. المركز الأخير."},"cu":{"why":"الـ Cu هو [Ar] 4s¹ 3d¹⁰: الـ 3d مليان (كله أزواج) والـ 4s فيه electron واحد، يبقى 1 unpaired، وده أقل عدد. المركز الأول."},"mn":{"why":"الـ Mn هو [Ar] 4s² 3d⁵: الـ 4s أزواج، وكل orbital في الـ 3d فيه electron واحد، يبقى 5 unpaired. المركز الرابع."},"ti":{"why":"الـ Ti هو [Ar] 4s² 3d²: الـ 4s أزواج، والـ 2 electrons بتوع الـ 3d كل واحد في orbital لوحده (الـ Hund's rule)، يبقى 2 unpaired. المركز التاني."}},"explanation":"اكتب الـ configuration بتاع كل ذرة (من جدول الكتاب) وعدّ الـ unpaired electrons في الـ 4s والـ 3d، واستخدم الـ Hund's rule في الـ 3d. الـ Ti: [Ar] 4s² 3d² → الـ 4s أزواج، والـ 3d [↑] [↑] [ ] [ ] [ ] → 2. الـ Cr: [Ar] 4s¹ 3d⁵ → 1 في الـ 4s + 5 في الـ 3d → 6. الـ Mn: [Ar] 4s² 3d⁵ → 0 + 5 → 5. الـ Co: [Ar] 4s² 3d⁷ → 0 + 3 → 3. الـ Cu: [Ar] 4s¹ 3d¹⁰ → 1 + 0 → 1. الترتيب التصاعدي: Cu (1) < Ti (2) < Co (3) < Mn (5) < Cr (6). أكتر إجابات غلط متوقعة: (1) الترتيب حسب الـ atomic number (Ti < Cr < Mn < Co < Cu)، من فكرة «electrons أكتر = unpaired electrons أكتر»؛ لكن بعد الـ Mn أي electron زيادة في الـ 3d بيعمل زوج، فالعدد بيقل. (2) كتابة الـ Cr على إنه [Ar] 4s² 3d⁴ والـ Cu على إنه [Ar] 4s² 3d⁹ (نسيان استثناء الـ chromium والـ copper)، وده بيدي الـ Cr 4 والـ Cu 1 ويحط الـ Cr تحت الـ Mn. (3) عدّ electrons الـ 3d لوحدها، وده بيخلي الـ Cr زي الـ Mn (5 لكل واحد) ويدي الـ Cu صفر. الكلمات المهمة: Hund's rule، single electron in each orbital، pairing، والـ 4s نص مليان في الـ Cr والـ Cu."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":66,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.electron-configuration-6","kind":"question","version":1,"ord":240,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.electron-configuration","concepts":[{"concept_id":"te.electron-configuration","role":"primary"},{"concept_id":"atom.hund-rule","role":"secondary"}],"title":"chem-s3-en.question-te.electron-configuration-6","payload":{"stem":"In the atoms of the first transition series, pairing of electrons in the 3d orbitals starts with the element ...","tags":["exam-style","choose","book_ref:Ch.1 p.8 point 1"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"$_{23}$V","correct":false},{"id":"b","text":"$_{25}$Mn","correct":false},{"id":"c","text":"$_{26}$Fe","correct":true},{"id":"d","text":"$_{30}$Zn","correct":false}],"difficulty":2,"concept_ids":["te.electron-configuration","atom.hund-rule"],"est_seconds":30},"layer":{"choices":{"a":{"why":"The p sublevel is half-filled at p³, but the d sublevel has 5 orbitals, so it takes one electron in each of its 5 orbitals (till 3d⁵) before pairing starts.","feedback":"Misconception: Transferring the p-sublevel picture (half-filled at p³) to d: thinking the 3d sublevel is half-filled at 3d³."},"b":{"why":"In Mn (3d⁵) each of the five 3d orbitals holds one electron, so no 3d orbital is paired yet; pairing starts after manganese.","feedback":"Misconception: Reading 'single electrons till manganese (3d⁵)' as 'pairing starts at manganese'."},"c":{"why":"Correct! The 3d orbitals take single electrons till Mn (3d⁵). Fe (3d⁶) is the first atom where an electron has to pair up."},"d":{"why":"In Zn all 3d electrons are paired, so Zn is where pairing ends, not where it starts.","feedback":"Misconception: Confusing the element where pairing is completed (3d¹⁰) with the element where pairing begins."}},"explanation":"The book (Ch.1, point 1 after the configuration table): after calcium ([Ar] 4s²), the five 3d orbitals are filled by a single electron in each orbital in sequence till manganese ($3d^5$). After manganese, pairing of electrons takes place in each orbital till zinc ($3d^{10}$) (Hund's rule). So the first atom with a paired 3d orbital is iron, $_{26}$Fe: [Ar] 4s² 3d⁶ → [↑↓] [↑] [↑] [↑] [↑]. Watch out: the d sublevel has 5 orbitals, so it is half-filled at $3d^5$, not $3d^3$ (that is the p sublevel, $p^3$)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"الـ p sublevel بيبقى نص مليان عند p³، لكن الـ d sublevel فيه 5 orbitals، فبياخد electron واحد في كل orbital من الخمسة (لحد 3d⁵) قبل ما الأزواج تبدأ.","feedback":"الفكرة الغلط: نقل صورة الـ p sublevel (نص مليان عند p³) على الـ d، والتفكير إن الـ 3d sublevel بيبقى نص مليان عند 3d³."},"b":{"why":"في الـ Mn (3d⁵) كل orbital من الـ 3d orbitals الخمسة فيه electron واحد، يعني لسه مفيش 3d orbital فيه زوج؛ الأزواج بتبدأ بعد الـ manganese.","feedback":"الفكرة الغلط: قراية «single electrons till manganese (3d⁵)» على إنها «الأزواج بتبدأ عند الـ manganese»."},"c":{"why":"صح! الـ 3d orbitals بياخدوا electrons فرادى لحد الـ Mn (3d⁵). والـ Fe (3d⁶) هو أول ذرة لازم electron فيها يعمل زوج."},"d":{"why":"في الـ Zn كل electrons الـ 3d عاملة أزواج، يعني الـ Zn هو اللي الأزواج بتخلص عنده، مش اللي بتبدأ عنده.","feedback":"الفكرة الغلط: الخلط بين العنصر اللي الأزواج بتكمل عنده (3d¹⁰) والعنصر اللي الأزواج بتبدأ عنده."}},"explanation":"الكتاب (الفصل الأول، النقطة 1 بعد جدول الكتاب): بعد الـ calcium ([Ar] 4s²)، الـ 3d orbitals الخمسة بيتملوا بـ single electron in each orbital بالتتابع لحد الـ manganese ($3d^5$). وبعد الـ manganese، الـ pairing بيحصل في كل orbital لحد الـ zinc ($3d^{10}$) (الـ Hund's rule). عشان كده أول ذرة فيها 3d orbital عامل زوج هي الـ iron، $_{26}$Fe: [Ar] 4s² 3d⁶ → [↑↓] [↑] [↑] [↑] [↑]. خلّي بالك: الـ d sublevel فيه 5 orbitals، فبيبقى نص مليان عند الـ $3d^5$، مش $3d^3$ (ده الـ p sublevel، $p^3$)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":67,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.transition-series-4","kind":"question","version":1,"ord":241,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.transition-series","concepts":[{"concept_id":"te.transition-series","role":"primary"}],"title":"chem-s3-en.question-te.transition-series-4","payload":{"stem":"Choose the correct answer: The first transition series lies in the fourth period. From scandium to zinc, its elements fill ...","tags":["exam-style","choose","unit-review","book_ref:Ch.1 transition series, pp.4-5"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"the 3d sublevel successively, because 3d comes after 4s in the filling order","correct":true},{"id":"b","text":"the 4d sublevel successively, because the series is in the fourth period","correct":false},{"id":"c","text":"the 4s sublevel successively, because 4s is the outermost sublevel","correct":false},{"id":"d","text":"the 3d sublevel successively, because 3d fills before 4s","correct":false}],"book_ref":"Ch.1 transition series, pp.4-5","difficulty":2,"concept_ids":["te.transition-series"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: 4s is filled at calcium, then 3d fills from Sc to Zn."},"b":{"why":"That matches the sublevel to the period number, but scandium ($4s^2\\,3d^1$) starts 3d, not 4d.","feedback":"Misconception: The first series fills 4d because it is in period 4."},"c":{"why":"Calcium, just before scandium, is [Ar] $4s^2$: 4s is already full there, so the new electrons after it go to 3d.","feedback":"Misconception: The outermost sublevel is the one being filled."},"d":{"why":"Calcium, just before scandium, is [Ar] $4s^2$: 4s is filled first, and 3d fills after it.","feedback":"Misconception: 3d fills before 4s."}},"explanation":"In period n, the (n − 1)d sublevel is filled. So period 4 fills 3d. In the filling order, 4s fills first, at potassium and calcium. Then 3d fills, from scandium ($3d^1$) to zinc ($3d^{10}$). Key words: the (3d) sublevel is filled successively, in the fourth period after calcium. Most likely wrong answer: 4d, matching the sublevel to the period number."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ 4s بيتملي عند الـ calcium، وبعدين الـ 3d بيتملي من الـ Sc للـ Zn."},"b":{"why":"كده إنت ربطت رقم الـ sublevel برقم الـ period. الـ scandium ($4s^2\\,3d^1$) بيبدأ الـ 3d، مش الـ 4d.","feedback":"الفكرة الغلط: إن الـ first series بتملا الـ 4d عشان هي في الـ period 4."},"c":{"why":"الـ calcium، اللي قبل الـ scandium على طول، هو [Ar] $4s^2$: الـ 4s اتملى خلاص عنده، والـ electrons الجديدة بعده بتدخل الـ 3d.","feedback":"الفكرة الغلط: إن الـ sublevel الخارجي هو اللي بيتملي."},"d":{"why":"الـ calcium اللي قبل الـ scandium على طول هو [Ar] $4s^2$، يعني الـ 4s اتملى الأول، قبل الـ 3d.","feedback":"الفكرة الغلط: إن الـ 3d بيتملي قبل الـ 4s."}},"explanation":"في الـ period n، الـ (n − 1)d sublevel هو اللي بيتملي. يبقى الـ period 4 بتملا الـ 3d. في ترتيب الملء، الـ 4s بيتملي الأول، عند الـ potassium والـ calcium. وبعدين الـ 3d بيتملي، من الـ scandium ($3d^1$) للـ zinc ($3d^{10}$). الكلمات المهمة: 'the (3d) sublevel is filled successively'، 'in the fourth period after calcium'. أكتر إجابة غلط متوقعة: 4d، لما تربط رقم الـ sublevel برقم الـ period."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":63,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":4,"page_to":4,"section_key":"ch1.te.series","section_title":"The main transition elements (d-block) and the four transition series","section_path":["Transition Elements","The transition elements","The main transition elements (d-block) and the four transition series"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-mn-4","kind":"question","version":1,"ord":242,"group_id":"chem-s3-en.ch1.practice.te-configuration","primary_concept_id":"te.uses-mn","concepts":[{"concept_id":"te.uses-mn","role":"primary"},{"concept_id":"te.oxidation-states-trend","role":"secondary"}],"title":"chem-s3-en.question-te.uses-mn-4","payload":{"stem":"Choose the correct answer: Potassium permanganate ($\\ce{KMnO4}$) is used as ..., and the oxidation state of manganese in it is ... (K = +1, O = −2)","tags":["exam-style","two-step","unit-review","book_ref:Ch.1 economic importance 5-Manganese, p.6; table, p.8"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"an antiseptic substance ... +7","correct":true},{"id":"b","text":"a fungicide ... +7","correct":false},{"id":"c","text":"an antiseptic substance ... +8","correct":false},{"id":"d","text":"a strong oxidizing agent in the dry cell ... +4","correct":false}],"book_ref":"Ch.1 economic importance 5-Manganese, p.6; table, p.8","difficulty":2,"concept_ids":["te.uses-mn","te.oxidation-states-trend"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: $\\ce{KMnO4}$ is an antiseptic, and +1 + x − 8 = 0 gives +7."},"b":{"why":"The book pairs the fungicide with a different manganese compound, $\\ce{MnSO4}$.","feedback":"Misconception: Swapping $\\ce{KMnO4}$ (antiseptic) and $\\ce{MnSO4}$ (fungicide)."},"c":{"why":"Potassium adds +1 to the sum: +1 + x − 8 = 0 gives +7, not +8.","feedback":"Misconception: Leaving potassium out of the sum (x − 8 = 0)."},"d":{"why":"That use and state fit $\\ce{MnO2}$; in $\\ce{KMnO4}$ manganese is +7, and its own use is as an antiseptic.","feedback":"Misconception: Confusing $\\ce{KMnO4}$ with $\\ce{MnO2}$."}},"explanation":"Use: the book lists $\\ce{KMnO4}$ as an antiseptic substance. $\\ce{MnSO4}$ is the fungicide, and $\\ce{MnO2}$ is the oxidizing agent in the dry cell. Oxidation state: +1 + x + 4(−2) = 0, so x = +7. This is manganese's highest oxidation state. It equals its group number (VIIB)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ $\\ce{KMnO4}$ مادة antiseptic، و +1 + x − 8 = 0 بتدّي +7."},"b":{"why":"الكتاب بيربط الـ fungicide بـ compound تاني فيه manganese، هو الـ $\\ce{MnSO4}$.","feedback":"الفكرة الغلط: إنك تبدّل الـ $\\ce{KMnO4}$ (antiseptic) بالـ $\\ce{MnSO4}$ (fungicide)."},"c":{"why":"الـ K بيضيف +1 للمجموع: +1 + x − 8 = 0، فالـ Mn بيبقى +7 مش +8.","feedback":"الفكرة الغلط: إنك تسيب الـ potassium برّه المجموع (x − 8 = 0)."},"d":{"why":"الاستخدام والـ oxidation state دول بتوع الـ $\\ce{MnO2}$، مش الـ $\\ce{KMnO4}$.","feedback":"الفكرة الغلط: إنك تلخبط بين الـ $\\ce{KMnO4}$ والـ $\\ce{MnO2}$."}},"explanation":"الاستخدام: الكتاب بيذكر الـ $\\ce{KMnO4}$ كـ antiseptic substance. أما الـ $\\ce{MnSO4}$ فهو الـ fungicide، والـ $\\ce{MnO2}$ هو الـ oxidizing agent في الـ dry cell. الـ oxidation state: +1 + x + 4(−2) = 0، يعني x = +7. وده أعلى oxidation state للـ manganese، وبيساوي رقم الـ group بتاعه (VIIB)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":77,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-phys.states-melting-boiling-1","kind":"question","version":1,"ord":263,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"phys.states-melting-boiling","concepts":[{"concept_id":"phys.states-melting-boiling","role":"primary"}],"title":"chem-s3-en.question-phys.states-melting-boiling-1","payload":{"stem":"At normal air pressure, pure water boils at 100 °C and ethanol (alcohol) boils at 78 °C. What does this tell you?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"The forces between water particles are stronger than those between ethanol particles.","correct":true},{"id":"b","text":"The forces between ethanol particles are stronger, because ethanol boils first.","correct":false},{"id":"c","text":"Water particles are heavier, so water needs more heating to boil.","correct":false},{"id":"d","text":"Nothing, because the boiling point depends on how much liquid you heat.","correct":false}],"book_ref":"Background for Ch.1 general properties, point 3, p.13 (high melting and boiling points)","difficulty":2,"concept_ids":["phys.states-melting-boiling"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right. Water needs more heating before its particles break free, so its forces are stronger."},"b":{"why":"Boiling first means less heating was needed, which points to weaker forces between ethanol particles.","feedback":"Misconception: A lower boiling point means stronger forces between particles."},"c":{"why":"In fact, an ethanol particle is heavier than a water particle. The forces between the particles decide the boiling point, not their mass.","feedback":"Misconception: Heavier particles always give a higher boiling point (mass, not forces, decides)."},"d":{"why":"A cup and a pot of pure water both boil at 100 °C: the amount does not change the boiling point.","feedback":"Misconception: The boiling point depends on the amount of substance."}},"explanation":"To boil, particles must break free from each other. Stronger forces need more heating, so the boiling point is higher. Water boils at 100 °C and ethanol at 78 °C. So water particles hold each other more strongly. Mass is not the reason: an ethanol particle is heavier than a water particle. The amount of liquid does not change the boiling point either. Key words: stronger forces between particles, higher boiling point."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الماية محتاجة تسخين أكتر قبل ما الـ particles بتاعتها تفلت من بعضها، يعني الـ forces بتاعتها أقوى."},"b":{"why":"إنها تغلي الأول معناه إنها احتاجت تسخين أقل، وده بيشاور على forces أضعف بين particles الـ ethanol.","feedback":"الفكرة الغلط: إن الـ boiling point الأقل معناها forces أقوى بين الـ particles."},"c":{"why":"في الحقيقة، الـ particle بتاعة الـ ethanol أتقل من particle الماية. الـ forces اللي بين الـ particles هي اللي بتحدد الـ boiling point، مش كتلتها.","feedback":"الفكرة الغلط: إن الـ particles الأتقل دايمًا بتدي boiling point أعلى (يعني الكتلة هي اللي بتحدد، مش الـ forces)."},"d":{"why":"كوباية ماية نقية وحلة ماية نقية الاتنين بيغلوا عند 100 °C: الكمية مابتغيّرش الـ boiling point.","feedback":"الفكرة الغلط: إن الـ boiling point بتعتمد على كمية المادة."}},"explanation":"عشان المادة تغلي، الـ particles لازم تفلت من بعضها. والـ forces الأقوى محتاجة تسخين أكتر، فالـ boiling point بتطلع أعلى. الماية بتغلي عند 100 °C والـ ethanol عند 78 °C، يعني particles الماية ماسكة في بعضها بقوة أكبر. والكتلة مش هي السبب: الـ particle بتاعة الـ ethanol أتقل من particle الماية. وكمان كمية الـ liquid مش بتغيّر الـ boiling point. الكلمات المهمة: stronger forces between particles، higher boiling point."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":15,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.states-melting-boiling-2","kind":"question","version":1,"ord":264,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"phys.states-melting-boiling","concepts":[{"concept_id":"phys.states-melting-boiling","role":"primary"}],"title":"chem-s3-en.question-phys.states-melting-boiling-2","payload":{"stem":"The table gives the melting and boiling points of three substances. Which one is a liquid at 100 °C?","tags":["diagnostic","prerequisite","data"],"type":"mcq","bloom":"apply","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["P",-20,80],["Q",30,290],["R",120,400]],"caption":"Three substances at normal air pressure","headers":["Substance","Melting point (°C)","Boiling point (°C)"]},"children":[]}}},"choices":[{"id":"a","text":"P","correct":false},{"id":"b","text":"Q","correct":true},{"id":"c","text":"R","correct":false}],"book_ref":"Background for Ch.1 general properties, point 3, p.13 (melting and boiling points)","difficulty":2,"concept_ids":["phys.states-melting-boiling"],"est_seconds":50},"layer":{"choices":{"a":{"why":"100 °C is above P's melting point, but also above its boiling point (80 °C), so P is a gas at 100 °C.","feedback":"Misconception: Compares the temperature with the melting point only; forgets that above the boiling point a substance is a gas."},"b":{"why":"Right. 100 °C lies between Q's melting point (30 °C) and its boiling point (290 °C)."},"c":{"why":"100 °C is below R's boiling point, but also below its melting point (120 °C), so R is still solid.","feedback":"Misconception: Compares the temperature with the boiling point only; forgets that below the melting point a substance is solid."}},"explanation":"A substance is a liquid between its melting point and its boiling point. Below the melting point it is a solid. Above the boiling point it is a gas. P: 100 °C is above its boiling point (80 °C), so P is a gas. Q: 100 °C lies between 30 °C and 290 °C, so Q is a liquid. R: 100 °C is below its melting point (120 °C), so R is still solid. Compare the temperature with both values, not just one."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"100 °C أعلى من الـ melting point بتاعة P، لكن كمان أعلى من الـ boiling point بتاعتها (80 °C)، فـ P بتبقى gas عند 100 °C.","feedback":"الفكرة الغلط: إنك بتقارن درجة الحرارة بالـ melting point لوحدها، وبتنسى إن فوق الـ boiling point المادة بتبقى gas."},"b":{"why":"صح. 100 °C واقعة بين الـ melting point بتاعة Q (30 °C) والـ boiling point بتاعتها (290 °C)."},"c":{"why":"100 °C أقل من الـ boiling point بتاعة R، لكن كمان أقل من الـ melting point بتاعتها (120 °C)، فـ R لسه solid.","feedback":"الفكرة الغلط: إنك بتقارن درجة الحرارة بالـ boiling point لوحدها، وبتنسى إن تحت الـ melting point المادة بتبقى solid."}},"explanation":"المادة بتبقى liquid ما بين الـ melting point والـ boiling point بتوعها. تحت الـ melting point بتبقى solid، وفوق الـ boiling point بتبقى gas. P: درجة 100 °C أعلى من الـ boiling point بتاعتها (80 °C)، يعني P بقت gas. Q: درجة 100 °C واقعة بين 30 °C و290 °C، يعني Q بتبقى liquid. R: درجة 100 °C أقل من الـ melting point بتاعتها (120 °C)، يعني R لسه solid. قارن درجة الحرارة بالقيمتين مع بعض، مش بقيمة واحدة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":16,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.table","section_title":"Data table (atomic mass, radius, density, melting and boiling points)","section_path":["Transition Elements","The general properties of the first transition elements","Data table (atomic mass, radius, density, melting and boiling points)"],"relation":"beyond"}]},{"id":"chem-s3-en.question-bond.chemical-bond-basic-1","kind":"question","version":1,"ord":265,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"bond.chemical-bond-basic","concepts":[{"concept_id":"bond.chemical-bond-basic","role":"primary"}],"title":"chem-s3-en.question-bond.chemical-bond-basic-1","payload":{"stem":"In which substance are the atoms joined by covalent bonds?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"$\\ce{CaCl2}$","correct":false},{"id":"b","text":"$\\ce{NH3}$","correct":true},{"id":"c","text":"$\\ce{Na2O}$","correct":false}],"book_ref":"Background for Ch.1 general properties, point 3, p.13 (the metallic bond is another kind of chemical bond)","difficulty":2,"concept_ids":["bond.chemical-bond-basic"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Calcium is a metal. When a metal meets a non-metal, electrons are transferred, not shared, so the bond is ionic.","feedback":"Misconception: Any compound that contains a non-metal such as chlorine has covalent bonds."},"b":{"why":"Right. Nitrogen and hydrogen are both non-metals, so they share pairs of electrons."},"c":{"why":"Water is covalent because hydrogen is a non-metal. Sodium is a metal, so it gives electrons to oxygen and the bond in $\\ce{Na2O}$ is ionic.","feedback":"Misconception: Oxygen compounds are covalent, like water."}},"explanation":"Look at the kinds of atoms. A metal and a non-metal: the metal gives electrons, ions form, and the bond is ionic. Two non-metals: the atoms share pairs of electrons, and the bond is covalent. $\\ce{CaCl2}$ and $\\ce{Na2O}$ each contain a metal, so they are ionic. $\\ce{NH3}$ has only non-metals (N and H), so its bonds are covalent."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"الـ calcium ده metal. ولما metal يقابل non-metal، الـ electrons بتنتقل مش بتتشارك، فالـ bond بيبقى ionic.","feedback":"الفكرة الغلط: إن أي compound فيه non-metal زي الـ chlorine بتبقى الـ bonds بتاعته covalent."},"b":{"why":"صح. الـ nitrogen والـ hydrogen الاتنين non-metals، فبيتشاركوا في أزواج من الـ electrons."},"c":{"why":"الماية covalent عشان الـ hydrogen ده non-metal. لكن الـ sodium ده metal، فالـ bond في الـ $\\ce{Na2O}$ ionic.","feedback":"الفكرة الغلط: إن الـ compounds اللي فيها oxygen بتبقى covalent، زي الماية."}},"explanation":"بص على نوع الـ atoms. metal مع non-metal: الـ metal بيدي electrons، والـ ions بتتكوّن، والـ bond بيبقى ionic. اتنين non-metals: الـ atoms بتتشارك في أزواج من الـ electrons، والـ bond بيبقى covalent. الـ $\\ce{CaCl2}$ والـ $\\ce{Na2O}$ كل واحد فيهم فيه metal، يبقى ionic. أما الـ $\\ce{NH3}$ فمفيهوش غير non-metals (N و H)، يبقى الـ bonds بتاعته covalent."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":17,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-bond.chemical-bond-basic-2","kind":"question","version":2,"ord":266,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"bond.chemical-bond-basic","concepts":[{"concept_id":"bond.chemical-bond-basic","role":"primary"}],"title":"chem-s3-en.question-bond.chemical-bond-basic-2","payload":{"stem":"Potassium (K) has 1 outer electron. Sulphur (S) has 6 outer electrons. Which describes the bonding in potassium sulphide, $\\ce{K2S}$?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Each K atom gives one electron to S, and the ions formed attract.","correct":true},{"id":"b","text":"The K and S atoms share pairs of electrons with each other.","correct":false},{"id":"c","text":"The S atom gives two electrons, one to each K atom.","correct":false},{"id":"d","text":"No electrons move, because K and S are only mixed together.","correct":false}],"book_ref":"Background for Ch.1 general properties, point 3, p.13 (the metallic bond is another kind of chemical bond)","difficulty":2,"concept_ids":["bond.chemical-bond-basic"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Right. Two K atoms each give one electron, so S gains the two it needs."},"b":{"why":"Sharing happens between two non-metals. Potassium is a metal with one outer electron, and it gives that electron away.","feedback":"Misconception: All bonds are formed by sharing electrons."},"c":{"why":"Sulphur has 6 outer electrons and needs 2 more for a stable level, so it takes electrons rather than giving them.","feedback":"Misconception: The atom with more outer electrons gives electrons away."},"d":{"why":"$\\ce{K2S}$ is a compound with new properties, so the outer electrons must move: they do not stay in place as in a mixture.","feedback":"Misconception: A compound is just a mixture of its elements."}},"explanation":"Potassium is a metal with 1 outer electron. Sulphur is a non-metal that needs 2 more electrons. So two K atoms each give one electron to one S atom. $\\ce{K+}$ and $\\ce{S^2-}$ ions form. Opposite charges attract: this is an ionic bond. That is why the formula has two K for one S."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. اتنين K atoms، كل واحد بيدي electron واحد، فالـ S بياخد الاتنين اللي محتاجهم."},"b":{"why":"المشاركة بتحصل بين اتنين non-metals. والـ potassium ده metal عنده outer electron واحد، فهو بيديه مش بيشارك بيه.","feedback":"الفكرة الغلط: إن كل الـ bonds بتتكوّن بالمشاركة في الـ electrons."},"c":{"why":"الـ sulphur عنده 6 outer electrons ومحتاج 2 كمان عشان يوصل لمستوى مستقر، فالأقرب إنه ياخد مش يدي.","feedback":"الفكرة الغلط: إن الـ atom اللي عنده outer electrons أكتر هو اللي بيدي electrons."},"d":{"why":"الـ $\\ce{K2S}$ ده compound ليه خواص جديدة، يبقى لازم الـ outer electrons تنتقل؛ ده مش مجرد خليط.","feedback":"الفكرة الغلط: إن الـ compound مجرد خليط من العناصر بتاعته."}},"explanation":"الـ potassium ده metal عنده outer electron واحد. والـ sulphur ده non-metal محتاج 2 electrons كمان. فاتنين K atoms كل واحد بيدي electron واحد لـ S atom واحد. بيتكوّن ions الـ $\\ce{K+}$ والـ $\\ce{S^2-}$. والـ charges المختلفة بتتجاذب: وده الـ ionic bond. وعشان كده الصيغة فيها اتنين K قصاد S واحد."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":18,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-bond.metallic-bond-1","kind":"question","version":1,"ord":267,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"bond.metallic-bond","concepts":[{"concept_id":"bond.metallic-bond","role":"primary"}],"title":"chem-s3-en.question-bond.metallic-bond-1","payload":{"stem":"What holds the atoms together in a piece of silver metal?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Positive silver ions attracted to a sea of free valence electrons","correct":true},{"id":"b","text":"Pairs of electrons shared between two neighboring silver atoms","correct":false},{"id":"c","text":"Positive and negative silver ions attracting each other","correct":false}],"book_ref":"Background for Ch.1 general properties, point 3, p.13b (the strong metallic bond)","difficulty":2,"concept_ids":["bond.metallic-bond"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right. Each atom releases its valence electrons, and they hold the positive ions together."},"b":{"why":"Fixed shared pairs belong to the covalent bond between non-metals. In a metal, the electrons do not stay between two atoms; they move freely.","feedback":"Misconception: Metal atoms bond by sharing electron pairs (a covalent bond)."},"c":{"why":"Negative ions form when atoms gain electrons, and silver atoms do not take electrons from each other.","feedback":"Misconception: Metals bond like ionic compounds, with negative ions."}},"explanation":"In a metal, each atom releases its valence (outer) electrons. The atoms become positive ions in a regular crystal lattice. The free electrons move among the ions and hold them together. This is the metallic bond. It is not covalent: no fixed pairs are shared. It is not ionic: there are no negative ions."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. كل atom بيحرّر الـ valence electrons بتاعته، وهي اللي بتمسك الـ positive ions في بعض."},"b":{"why":"الأزواج المشتركة الثابتة دي بتاعة الـ covalent bond اللي بين الـ non-metals. في الـ metal، الـ electrons مابتفضلش بين اتنين atoms؛ هي بتتحرك بحرية.","feedback":"الفكرة الغلط: إن الـ metal atoms بتترابط بالمشاركة في electron pairs (يعني covalent bond)."},"c":{"why":"الـ negative ions بتتكوّن لما الـ atoms تاخد electrons، والـ silver atoms مش بتاخد electrons من بعض.","feedback":"الفكرة الغلط: إن الـ metals بتترابط زي الـ ionic compounds، وفيها negative ions."}},"explanation":"في الـ metal، كل atom بيحرّر الـ valence (outer) electrons بتاعته. فالـ atoms بتتحول لـ positive ions مترتبة في crystal lattice منتظمة. والـ free electrons بتتحرك بين الـ ions وبتمسكهم في بعض. ده هو الـ metallic bond. هو مش covalent: مفيش أزواج ثابتة بتتشارك. ومش ionic: مفيش negative ions."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":19,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-bond.metallic-bond-2","kind":"question","version":1,"ord":268,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"bond.metallic-bond","concepts":[{"concept_id":"bond.metallic-bond","role":"primary"}],"title":"chem-s3-en.question-bond.metallic-bond-2","payload":{"stem":"Lithium (Li) gives 1 valence electron per atom to its metallic bond. Beryllium (Be), the next element, gives 2. Which prediction about their melting points is correct?","tags":["diagnostic","prerequisite","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Be melts higher, because its extra free electron makes its metallic bond stronger.","correct":true},{"id":"b","text":"Be melts higher, because its atoms are heavier than lithium atoms.","correct":false},{"id":"c","text":"They melt at about the same temperature, because they are neighbors.","correct":false},{"id":"d","text":"Be melts higher, because its atoms share fixed pairs of electrons.","correct":false}],"book_ref":"Background for Ch.1 general properties, point 3, p.13b (the strong metallic bond)","difficulty":3,"concept_ids":["bond.metallic-bond"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right. Here, more electrons in the sea hold the positive ions more strongly."},"b":{"why":"Li is about 7 and Be about 9 in atomic mass; that small difference is not the reason. What changes is the number of free electrons each atom gives.","feedback":"Misconception: Heavier atoms always melt at higher temperatures."},"c":{"why":"Neighbors can differ a lot. Li gives 1 free electron to the sea and Be gives 2, so their bonds are not equal.","feedback":"Misconception: Neighboring metals have similar melting points."},"d":{"why":"Fixed shared pairs belong to non-metals. In a metal, the valence electrons go into a sea of free electrons.","feedback":"Misconception: Metal atoms are held by covalent electron pairs."}},"explanation":"In the metallic bond, positive ions are held by a sea of free valence electrons. Lithium gives 1 electron per atom; beryllium gives 2. For these two neighbors, more free electrons per atom make a stronger metallic bond. (Other factors also matter, so this is not a rule for every pair of metals.) A stronger bond needs more heat to break, so Be melts higher. Real values: Li melts at 181 °C, Be at 1287 °C. Mass is not the reason: Be is only slightly heavier than Li."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. هنا، electrons أكتر في البحر بتمسك الـ positive ions بقوة أكبر."},"b":{"why":"الـ atomic mass بتاعة الـ Li حوالي 7 والـ Be حوالي 9، والفرق الصغير ده مش هو السبب. اللي بيتغيّر فعلًا من الـ Li للـ Be هو عدد الـ free electrons لكل atom.","feedback":"الفكرة الغلط: إن الـ atoms الأتقل دايمًا بتنصهر عند درجات حرارة أعلى."},"c":{"why":"العناصر اللي جنب بعض ممكن تفرق جامد. الـ Li بيدي electron واحد للبحر والـ Be بيدي 2، فالعدد مش متساوي.","feedback":"الفكرة الغلط: إن الـ metals اللي جنب بعض في الجدول الـ melting points بتاعتها قريبة من بعض."},"d":{"why":"الأزواج المشتركة الثابتة دي بتاعة الـ non-metals. في الـ metal، الـ valence electrons بتتحرر وبتعمل بحر من الـ free electrons.","feedback":"الفكرة الغلط: إن الـ metal atoms ماسكها covalent electron pairs."}},"explanation":"في الـ metallic bond، الـ positive ions ماسكها بحر من الـ free valence electrons. الـ lithium بيدي electron واحد لكل atom، والـ beryllium بيدي 2. وفي حالة العنصرين الجيران دول، free electrons أكتر لكل atom بتعمل metallic bond أقوى. (فيه عوامل تانية ليها دور برضه، فدي مش قاعدة لأي اتنين metals.) والـ bond الأقوى محتاج حرارة أكتر عشان يتكسر، فالـ Be بينصهر عند درجة أعلى. القيم الحقيقية: الـ Li بينصهر عند 181 °C، والـ Be عند 1287 °C. والكتلة مش هي السبب: الـ Be أتقل من الـ Li بفرق صغير."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":20,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-phys.density-1","kind":"question","version":1,"ord":269,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"phys.density","concepts":[{"concept_id":"phys.density","role":"primary"}],"title":"chem-s3-en.question-phys.density-1","payload":{"stem":"A metal bar has a density of 7.9 g/cm³. You cut it into two equal halves. What is the density of one half?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"3.95 g/cm³","correct":false},{"id":"b","text":"7.9 g/cm³","correct":true},{"id":"c","text":"15.8 g/cm³","correct":false}],"book_ref":"Background for Ch.1 general properties, point 3, p.13c (high density)","difficulty":2,"concept_ids":["phys.density"],"est_seconds":40},"layer":{"choices":{"a":{"why":"The mass is halved, but so is the volume, so mass ÷ volume stays the same.","feedback":"Misconception: Density depends on the amount: half the mass gives half the density."},"b":{"why":"Right. Mass and volume are both halved, so their ratio does not change."},"c":{"why":"The volume is halved, but the mass is halved too, so the new mass ÷ new volume gives the same density.","feedback":"Misconception: A smaller piece has less volume, so it must be denser."}},"explanation":"Density = mass ÷ volume. Cutting the bar in half halves the mass and halves the volume. The ratio stays the same: 7.9 g/cm³. Density belongs to the substance, not to the size of the piece. Pieces of the same pure metal have the same density."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"الـ mass اتقسمت نصين، لكن كمان الـ volume اتقسم نصين، فالـ mass ÷ volume بتفضل زي ما هي.","feedback":"الفكرة الغلط: إن الـ density بتعتمد على الكمية: نص الـ mass يدي نص الـ density."},"b":{"why":"صح. الـ mass والـ volume الاتنين اتقسموا على 2، فالنسبة بينهم ما اتغيرتش."},"c":{"why":"الـ volume بقى النص، لكن الـ mass كمان بقت النص، فقسمة الـ mass الجديدة على الـ volume الجديد بتدّي نفس الـ density.","feedback":"الفكرة الغلط: إن الحتة الأصغر الـ volume بتاعها أقل، فلازم الـ density بتاعتها تبقى أعلى."}},"explanation":"الـ Density = mass ÷ volume. لما تقطع القالب نصين، الـ mass بتبقى النص والـ volume كمان بيبقى النص. فالنسبة بتفضل زي ما هي: 7.9 g/cm³. الـ density صفة للمادة نفسها، مش لحجم الحتة. وحتت نفس الـ metal النقي ليها نفس الـ density."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":21,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.density-2","kind":"question","version":1,"ord":270,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"phys.density","concepts":[{"concept_id":"phys.density","role":"primary"}],"title":"chem-s3-en.question-phys.density-2","payload":{"stem":"A metal cube has a mass of 33.6 g and a volume of 4 cm³. Calculate its density in g/cm³.","tags":["diagnostic","prerequisite","calculation"],"type":"numeric","bloom":"apply","answer":{"unit":"g/cm³","value":8.4,"tolerance":0.05},"book_ref":"Background for Ch.1 general properties, point 3, p.13c (high density)","difficulty":2,"concept_ids":["phys.density"],"est_seconds":45},"layer":{"explanation":"Density = mass ÷ volume = 33.6 g ÷ 4 cm³ = 8.4 g/cm³. Common mistake 1: multiplying, 33.6 × 4 = 134.4. Density is mass per unit volume, so divide. Common mistake 2: volume ÷ mass, 4 ÷ 33.6 = 0.12. The mass goes on top."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ Density = mass ÷ volume = 33.6 g ÷ 4 cm³ = 8.4 g/cm³. أول غلطة بتتكرر: إنك تضرب، 33.6 × 4 = 134.4. الـ density هي الـ mass لكل وحدة volume، يعني تقسم. تاني غلطة بتتكرر: إنك تقسم الـ volume على الـ mass، 4 ÷ 33.6 = 0.12. الـ mass هي اللي بتتحط فوق."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":22,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"beyond"}]},{"id":"chem-s3-en.question-te.atomic-mass-trend-1","kind":"question","version":1,"ord":271,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.atomic-mass-trend","concepts":[{"concept_id":"te.atomic-mass-trend","role":"primary"}],"title":"chem-s3-en.question-te.atomic-mass-trend-1","payload":{"stem":"Use the table. Which pair of neighboring elements does not follow the general trend of atomic mass?","tags":["exam-style","data","choose"],"type":"mcq","bloom":"understand","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["$\\ce{Sc}$",21,45,1.44],["$\\ce{Ti}$",22,47.9,1.32],["$\\ce{V}$",23,51,1.22],["$\\ce{Cr}$",24,52,1.17],["$\\ce{Mn}$",25,54.9,1.17],["$\\ce{Fe}$",26,55.9,1.16],["$\\ce{Co}$",27,58.9,1.16],["$\\ce{Ni}$",28,58.7,1.15],["$\\ce{Cu}$",29,63.5,1.17]],"caption":"Book's table, p.12 (for illustration only)","headers":["Element","Atomic number","Atomic mass","Atomic radius"]},"children":[]}}},"choices":[{"id":"a","text":"Cr and Mn","correct":false},{"id":"b","text":"Fe and Co","correct":false},{"id":"c","text":"Co and Ni","correct":true},{"id":"d","text":"Ni and Cu","correct":false}],"book_ref":"Ch.1 general properties, point 1 + data table, p.12","difficulty":2,"concept_ids":["te.atomic-mass-trend"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Cr and Mn have equal values in the radius column, not the atomic mass column.","feedback":"Misconception: Reads the atomic radius column (1.17, 1.17) instead of the atomic mass column."},"b":{"why":"From Fe to Co the atomic mass goes up, which follows the general trend.","feedback":"Misconception: Blames cobalt (58.9) as abnormal because it is larger than the next value."},"c":{"why":"Right. Nickel's atomic mass is lower than cobalt's, though its atomic number is higher."},"d":{"why":"A big rise is still a rise: the general trend is for atomic mass to increase.","feedback":"Misconception: Takes a large rise in atomic mass as the abnormality."}},"explanation":"The general trend: atomic mass increases gradually with increasing atomic number. Scan the atomic mass column from Sc to Cu. Every step rises except one: Co 58.9 to Ni 58.7. So nickel is abnormal. The book's reason: nickel has five stable isotopes with average mass 58.7 u. Equal values for Cr and Mn are in the radius column. The big rise from Ni to Cu still follows the trend."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"الـ Cr والـ Mn ليهم نفس القيمة في عمود الـ radius، مش في عمود الـ atomic mass.","feedback":"الفكرة الغلط: إنك تقرا عمود الـ atomic radius (1.17, 1.17) بدل عمود الـ atomic mass."},"b":{"why":"من الـ Fe للـ Co الـ atomic mass بتطلع، وده ماشي مع الاتجاه العام.","feedback":"الفكرة الغلط: إن الـ cobalt (58.9) هو الشاذ عشان قيمته أكبر من القيمة اللي بعده."},"c":{"why":"صح. الـ atomic mass بتاعة الـ nickel أقل من بتاعة الـ cobalt، مع إن الـ atomic number بتاعه أكبر."},"d":{"why":"الزيادة الكبيرة برضه زيادة: الاتجاه العام إن الـ atomic mass بتزيد.","feedback":"الفكرة الغلط: إن الزيادة الكبيرة في الـ atomic mass هي الشذوذ."}},"explanation":"الاتجاه العام: الـ atomic mass بتزيد تدريجيًا مع زيادة الـ atomic number. امشي على عمود الـ atomic mass من الـ Sc للـ Cu. كل خطوة بتطلع ما عدا واحدة: من الـ Co 58.9 للـ Ni 58.7. يبقى الـ nickel abnormal. وسبب الكتاب: الـ nickel ليه خمس stable isotopes متوسط كتلتهم 58.7 u. القيم المتساوية للـ Cr والـ Mn موجودة في عمود الـ radius. والزيادة الكبيرة من الـ Ni للـ Cu لسه ماشية مع الاتجاه العام."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":23,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.mass","section_title":"The atomic mass","section_path":["Transition Elements","The general properties of the first transition elements","The atomic mass"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.atomic-radius-1","kind":"question","version":1,"ord":272,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.atomic-radius","concepts":[{"concept_id":"te.atomic-radius","role":"primary"}],"title":"chem-s3-en.question-te.atomic-radius-1","payload":{"stem":"Give reasons: The decrease in atomic radius across the first transition series is small.","tags":["exam-style","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: two opposite factors. (1) The effective nuclear charge increases, so the nuclear attraction to electrons increases; this decreases the atomic radius. (2) The number of electrons in the 3d sublevel increases, so the repulsion between them increases; this increases the atomic radius. (3) The two factors oppose each other, so the atomic radius stays relatively constant (nearly constant from Cr to Cu).","book_ref":"Ch.1 general properties, point 2, pp.12-13; Evaluation Q7.4, p.27","difficulty":3,"concept_ids":["te.atomic-radius"],"est_seconds":120},"layer":{"explanation":"A full answer names both factors and their opposite effects. Factor 1: the effective nuclear charge increases, so the nuclear attraction to electrons increases. This tends to decrease the radius. Factor 2: more electrons enter the 3d sublevel, so the repulsion between them increases. This tends to increase the radius. The two factors oppose each other, so the radius changes little. Most likely wrong answer: only the nuclear charge. Alone, it would make the radius fall sharply, as across period 3."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الإجابة الكاملة بتذكر العاملين وتأثيرهم العكسي. العامل 1: الـ effective nuclear charge بتزيد، فالـ nuclear attraction للـ electrons بتزيد، وده بيميل يصغّر الـ radius. العامل 2: electrons أكتر بتدخل الـ 3d sublevel، فالتنافر بينهم بيزيد، وده بيميل يكبّر الـ radius. العاملين عكس بعض، فالـ radius بيتغيّر تغيير بسيط. أشهر غلطة: إنك تذكر الـ nuclear charge لوحدها. لو كانت لوحدها، الـ radius كان هيقل بشكل حاد، زي ما بيحصل في الـ period 3."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":24,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"4","relation":"from_book"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.metallic-properties-1","kind":"question","version":1,"ord":273,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.metallic-properties","concepts":[{"concept_id":"te.metallic-properties","role":"primary"}],"title":"chem-s3-en.question-te.metallic-properties-1","payload":{"stem":"Choose the correct answer: The metallic property appears clearly in the first transition elements, as all of them are ...","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"solids with metallic luster that conduct heat and electricity well","correct":true},{"id":"b","text":"solids with limited chemical activity, like copper","correct":false,"misconception_id":"te.metallic-properties.mc1"},{"id":"c","text":"active metals that replace the hydrogen of water strongly","correct":false,"misconception_id":"te.metallic-properties.mc2"},{"id":"d","text":"solids that go rusty when exposed to moist air","correct":false}],"book_ref":"Ch.1 general properties, point 3a and 3d, p.13","difficulty":2,"concept_ids":["te.metallic-properties"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right. These are shared by every element from Sc to Cu."},"b":{"why":"Copper is only one member: iron goes rusty in moist air, so not every member reacts as little as copper.","feedback":"Misconception: All transition metals are unreactive like copper."},"c":{"why":"That describes one member, scandium: copper water pipes do not react with water, so the series does not share this activity.","feedback":"Misconception: All transition metals react strongly with water."},"d":{"why":"Rusting is iron's behavior, so it describes one member; copper and scandium do not share it. The shared properties are metallic luster and good conductivity.","feedback":"Misconception: Generalizes iron's rusting to the whole series."}},"explanation":"Book point 3a: all of them are solids, with metallic luster and good conductivity of heat and electricity. These properties are shared by the whole series. Chemical activity is different: it varies (point 3d). Copper has limited activity, iron is moderate, and scandium is highly active. So options about activity describe only one member each."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. دي خواص مشتركة بين كل العناصر من الـ Sc لحد الـ Cu."},"b":{"why":"الـ copper ده مجرد عنصر واحد من السلسلة. بوابة iron متسابة في هوا رطب بتصدّى، فمش كل العناصر نشاطها محدود زي الـ copper.","feedback":"الفكرة الغلط: إن كل الـ transition metals نشاطها محدود زي الـ copper."},"c":{"why":"ده وصف لعنصر واحد. مواسير الماية اللي من الـ copper مابتتفاعلش مع الماية، فمش كل العناصر بتحل محل الـ hydrogen of water بقوة.","feedback":"الفكرة الغلط: إن كل الـ transition metals بتتفاعل مع الماية بقوة."},"d":{"why":"الصدأ ده تصرّف الـ iron، مش خاصية مشتركة بين كل عناصر السلسلة: الـ copper مثلًا نشاطه محدود.","feedback":"الفكرة الغلط: إن صدأ الـ iron بيتعمّم على السلسلة كلها."}},"explanation":"البند 3a في الكتاب: كلهم solids، ليهم metallic luster، وبيوصّلوا الحرارة والكهربا كويس. الخواص دي مشتركة في السلسلة كلها. إنما الـ chemical activity حاجة تانية: بتختلف (البند 3d). الـ copper نشاطه محدود، والـ iron متوسط، والـ scandium نشاطه عالي. عشان كده الاختيارات اللي بتتكلم عن النشاط، كل واحد فيها بيوصف عنصر واحد تحديدًا."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":25,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.high-melting-points-1","kind":"question","version":1,"ord":274,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.high-melting-points","concepts":[{"concept_id":"te.high-melting-points","role":"primary"}],"title":"chem-s3-en.question-te.high-melting-points-1","payload":{"stem":"Give reasons: The first transition elements have high melting and boiling points.","tags":["exam-style","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) They have a strong metallic bond. (2) This bond is formed by the sharing of both 4s and 3d electrons.","book_ref":"Ch.1 general properties, point 3b, p.13; Evaluation Q7.5, p.27","difficulty":3,"concept_ids":["te.high-melting-points"],"est_seconds":90},"layer":{"explanation":"To melt or boil a metal, the metallic bond must be overcome. In these elements, both 4s and 3d electrons share in forming the metallic bond. Here, the many electrons sharing in the bond make it strong, so a lot of heat is needed. Key words: strong metallic bond, sharing of both 4s and 3d electrons. Most likely wrong answer: 'their atoms are heavy'. Mass does not decide melting points. Another wrong answer: 'only 4s electrons form the bond'. Then their metallic bond would be weak, more like calcium's (Ca melts at 842 °C)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"عشان تصهر metal أو تغليه، لازم تتغلب على الـ metallic bond. في العناصر دي، الـ 4s والـ 3d electrons الاتنين بيشاركوا في تكوين الـ metallic bond. وعدد الـ electrons الكبير اللي بيشارك في الـ bond هنا بيخليه قوي، فمحتاج حرارة كتير. الكلمات المفتاحية: strong metallic bond، و sharing of both 4s and 3d electrons. أشهر إجابة غلط: «إن ذراتها تقيلة». الكتلة مش هي اللي بتحدد الـ melting points. إجابة غلط تانية: «إن الـ 4s electrons لوحدها هي اللي بتعمل الـ bond». لو كده، كان الـ metallic bond بتاعها هيبقى ضعيف، أقرب للـ metallic bond بتاع الـ Ca (اللي بينصهر عند 842 °C)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":26,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"5","relation":"from_book"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.density-trend-1","kind":"question","version":1,"ord":275,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.density-trend","concepts":[{"concept_id":"te.density-trend","role":"primary"}],"title":"chem-s3-en.question-te.density-trend-1","payload":{"stem":"Give reasons: The density of the first transition elements increases with increasing atomic number.","tags":["exam-style","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) The atomic mass increases with atomic number. (2) The atomic size (radius) stays relatively constant. (3) So more mass is packed into nearly the same volume, and the density increases.","book_ref":"Ch.1 general properties, point 3c, p.13","difficulty":3,"concept_ids":["te.density-trend"],"est_seconds":90},"layer":{"explanation":"Density = mass ÷ volume. Across the series, the atomic mass increases. But the atomic size stays relatively constant, because of the two opposite factors. So each atom adds more mass in nearly the same volume. The density therefore increases. Key words: atomic mass increases, atomic size relatively constant. Most likely wrong answer: 'the atoms get much smaller'. From Cr to Cu, the radius hardly changes, yet density still rises."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"Density = mass ÷ volume. على طول السلسلة، الـ atomic mass بيزيد. لكن الـ atomic size بيفضل ثابت نسبيًا، بسبب العاملين المتعاكسين. فكل ذرة بتضيف mass أكتر في نفس الـ volume تقريبًا، وعشان كده الـ density بتزيد. الكلمات المهمة: atomic mass increases، و atomic size relatively constant. أكتر إجابة غلط متوقعة: 'the atoms get much smaller' (إن الذرات بتصغر كتير). من الـ Cr للـ Cu، الـ radius تقريبًا مابيتغيرش، ومع ذلك الـ density بتزيد."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":27,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.atomic-mass-trend-2","kind":"question","version":1,"ord":276,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.atomic-mass-trend","concepts":[{"concept_id":"te.atomic-mass-trend","role":"primary"}],"title":"chem-s3-en.question-te.atomic-mass-trend-2","payload":{"stem":"Give reasons: Nickel ($_{28}$Ni) is abnormal in the gradual increase of atomic mass across the first transition series.","tags":["exam-style","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) Atomic mass increases gradually with increasing atomic number. (2) Nickel's atomic mass (58.7 u) is less than cobalt's (58.9 u), although nickel comes after cobalt. (3) Nickel has five stable isotopes. (4) Its atomic mass, 58.7 u, is the average mass of these isotopes.","book_ref":"Ch.1 general properties, point 1, p.12","difficulty":3,"concept_ids":["te.atomic-mass-trend"],"est_seconds":90},"layer":{"explanation":"Atomic mass usually rises with atomic number. Nickel (Z = 28) comes after cobalt (Z = 27), but its atomic mass is smaller. The reason is in its isotopes. Nickel has five stable isotopes, and 58.7 u is their average mass. Most nickel atoms are the light isotope nickel-58, so the average stays low. Key words: five stable isotopes, average mass 58.7 u. Most likely wrong answer: 'nickel has fewer protons'. No: nickel has 28 protons, cobalt 27. Another wrong answer: 'the value is a misprint'. It is a real average."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ atomic mass غالبًا بتزيد مع الـ atomic number. الـ nickel (Z = 28) بييجي بعد الـ cobalt (Z = 27)، لكن الـ atomic mass بتاعته أصغر. السبب في الـ isotopes بتاعته: الـ nickel ليه خمس stable isotopes، والـ 58.7 u ده متوسط كتلتهم. وأغلب ذرات الـ nickel هي الـ isotope الخفيف nickel-58، فالمتوسط بيفضل واطي. الكلمات المهمة: five stable isotopes، average mass 58.7 u. أشهر إجابة غلط: إن الـ nickel فيه protons أقل. لأ: الـ nickel فيه 28 protons والـ cobalt فيه 27. وإجابة غلط تانية: إن القيمة دي غلطة مطبعية. لأ، دي متوسط حقيقي."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":28,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.mass","section_title":"The atomic mass","section_path":["Transition Elements","The general properties of the first transition elements","The atomic mass"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.atomic-radius-2","kind":"question","version":1,"ord":277,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.atomic-radius","concepts":[{"concept_id":"te.atomic-radius","role":"primary"}],"title":"chem-s3-en.question-te.atomic-radius-2","payload":{"stem":"The graph shows the atomic radius from Sc to Cu. In which part does the increasing effective nuclear charge clearly win over the repulsion between 3d electrons?","tags":["exam-style","data","graph"],"type":"mcq","bloom":"analyze","figure":{"root":"c","elements":{"c":{"type":"Chart","props":{"kind":"line","series":[{"name":"Atomic radius","points":[{"x":"Sc","y":1.44},{"x":"Ti","y":1.32},{"x":"V","y":1.22},{"x":"Cr","y":1.17},{"x":"Mn","y":1.17},{"x":"Fe","y":1.16},{"x":"Co","y":1.16},{"x":"Ni","y":1.15},{"x":"Cu","y":1.17}]}],"caption":"Book's table, p.12 (for illustration only)","x_label":"Element","y_label":"Atomic radius"},"children":[]}}},"choices":[{"id":"a","text":"From Sc to Cr","correct":true},{"id":"b","text":"From Cr to Ni","correct":false},{"id":"c","text":"From Ni to Cu","correct":false},{"id":"d","text":"Nowhere in the series","correct":false}],"book_ref":"Ch.1 general properties, point 2 + data table, pp.12-13","difficulty":4,"concept_ids":["te.atomic-radius"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right. The radius clearly falls there, so the nuclear attraction wins."},"b":{"why":"The nuclear charge is larger there, but the graph shows the radius nearly constant from Cr to Ni, so the attraction does not clearly win.","feedback":"Misconception: The nuclear charge is largest late in the series, so its effect must win there."},"c":{"why":"From Ni to Cu the radius goes up slightly, and a stronger pull would make the atom smaller, not bigger.","feedback":"Misconception: Takes a rise in radius as the effect of nuclear attraction."},"d":{"why":"The book's 'nearly constant' covers only part of the series: from Sc to Cr the graph is not flat, and the radius falls clearly.","feedback":"Misconception: Overgeneralizes 'nearly constant' to the whole series."}},"explanation":"When the effective nuclear charge wins, the radius clearly decreases. From Sc (1.44) to Cr (1.17), the radius falls clearly. So the nuclear attraction wins there. From Cr to Cu, the values stay between 1.15 and 1.17. There the 3d repulsion balances the attraction, so the radius is nearly constant. A larger nuclear charge alone does not mean a smaller atom. The repulsion must also be counted."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ radius بيقل بوضوح هناك، يعني الـ nuclear attraction هي اللي بتكسب."},"b":{"why":"الـ nuclear charge أكبر هناك، لكن الرسم بيبيّن إن الـ radius ثابت تقريبًا من الـ Cr للـ Ni، يعني الجذب مش بيكسب بوضوح.","feedback":"الفكرة الغلط: إن الـ nuclear charge أكبر ما يكون في آخر السلسلة، فلازم تأثيرها هو اللي يكسب هناك."},"c":{"why":"من الـ Ni للـ Cu الـ radius بيزيد زيادة صغيرة، والشدّ الأقوى كان هيخلّي الذرة أصغر، مش أكبر.","feedback":"الفكرة الغلط: إن زيادة الـ radius دي جاية من تأثير الـ nuclear attraction."},"d":{"why":"«ثابت تقريبًا» في كلام الكتاب بتغطي جزء من السلسلة، مش السلسلة كلها: من الـ Sc للـ Cr الرسم مش مسطّح، والـ radius بينزل بوضوح.","feedback":"الفكرة الغلط: إن «ثابت تقريبًا» ينطبق على السلسلة كلها."}},"explanation":"لما الـ effective nuclear charge تكسب، الـ radius بيقل بوضوح. من الـ Sc (1.44) للـ Cr (1.17) الـ radius بينزل بوضوح، يعني الـ nuclear attraction هي اللي كسبانة هناك. من الـ Cr للـ Cu القيم بتفضل بين 1.15 و1.17؛ هنا التنافر بين الـ 3d electrons بيوازن الجذب، فالـ radius ثابت تقريبًا. الـ nuclear charge الأكبر لوحدها مش معناها ذرة أصغر؛ لازم تحسب حساب التنافر كمان."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":29,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.metallic-properties-2","kind":"question","version":1,"ord":278,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.metallic-properties","concepts":[{"concept_id":"te.metallic-properties","role":"primary"}],"title":"chem-s3-en.question-te.metallic-properties-2","payload":{"stem":"Consider the following statements:\n(I) Iron has moderate activity: it goes rusty if exposed to air.\n(II) Copper replaces the hydrogen of water strongly.\n(III) Scandium is a good conductor of heat and electricity.\nWhich of these statements is/are correct?","tags":["exam-style","statements-I-II-III"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"(I) only","correct":false},{"id":"b","text":"(I) and (II)","correct":false},{"id":"c","text":"(I) and (III)","correct":true},{"id":"d","text":"(II) and (III)","correct":false}],"book_ref":"Ch.1 general properties, point 3a and 3d, p.13","difficulty":3,"concept_ids":["te.metallic-properties"],"est_seconds":70},"layer":{"choices":{"a":{"why":"(III) is also correct: the book gives metallic luster and good conductivity of heat and electricity to the elements of the whole series, scandium included.","feedback":"Misconception: A highly active metal like scandium is not a good conductor; conductivity belongs to metals like copper."},"b":{"why":"(II) is wrong: copper has limited chemical activity, which is why copper water pipes last for decades; scandium is the one that replaces the hydrogen of water strongly.","feedback":"Misconception: Swaps copper and scandium in chemical activity."},"c":{"why":"Right. Statement (II) gives copper the activity of another member."},"d":{"why":"(I) is correct and was left out: iron has moderate activity and goes rusty if exposed to air. And (II) is wrong: copper has limited activity.","feedback":"Misconception: Rusting is not a sign of chemical activity, so iron is unreactive."}},"explanation":"(I) is correct: the book calls iron moderate, since it goes rusty if exposed to air. (II) is wrong: copper has limited chemical activity. Scandium is the one that replaces the hydrogen of water strongly. (III) is correct: all of them have metallic luster and good conductivity of heat and electricity. Activity varies from member to member, but conductivity is shared."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"(III) كمان صح: الكتاب بيدي الـ good conductivity of heat and electricity لكل عناصر السلسلة، والـ scandium منهم.","feedback":"الفكرة الغلط: إن metal نشيط جدًا زي الـ scandium مايبقاش good conductor، وإن الـ conductivity دي بتاعة metals زي الـ copper."},"b":{"why":"مواسير الـ copper بتاعة المية بتعيش عشرات السنين، ودي ماكانتش هتحصل لو الـ copper بيحل محل الـ hydrogen of water بقوة. الـ copper نشاطه limited، فـ (II) غلط.","feedback":"الفكرة الغلط: إنك بتبدّل الـ copper والـ scandium في الـ chemical activity."},"c":{"why":"صح. الجملة (II) بتدي الـ copper نشاط عنصر تاني في السلسلة."},"d":{"why":"الصدأ ده تفاعل مع الهوا، والـ iron نشاطه moderate فعلًا مقارنةً بباقي عناصر السلسلة، فـ (I) صح وإنت سبتها. و(II) غلط: الـ copper نشاطه limited.","feedback":"الفكرة الغلط: إن الصدأ مش علامة على chemical activity، فالـ iron مش نشيط."}},"explanation":"(I) صح: الكتاب بيقول إن الـ iron نشاطه moderate، عشان بيصدّى لو اتعرض للهوا. (II) غلط: الـ copper الـ chemical activity بتاعته limited. الـ scandium هو اللي بيحل محل الـ hydrogen of water بقوة. (III) صح: كلهم ليهم metallic luster و good conductivity of heat and electricity. النشاط بيختلف من عنصر للتاني، لكن الـ conductivity صفة مشتركة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":30,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.high-melting-points-2","kind":"question","version":2,"catalog_version":1,"ord":279,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.high-melting-points","concepts":[{"concept_id":"te.high-melting-points","role":"primary"}],"title":"chem-s3-en.question-te.high-melting-points-2","payload":{"stem":"Use the table. Compare vanadium and iron. Which conclusion is correct?","tags":["exam-style","data","choose"],"type":"mcq","bloom":"analyze","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["$\\ce{Sc}$",45,1397],["$\\ce{Ti}$",47.9,1680],["$\\ce{V}$",51,1710],["$\\ce{Cr}$",52,1890],["$\\ce{Mn}$",54.9,1247],["$\\ce{Fe}$",55.9,1538],["$\\ce{Co}$",58.9,1490],["$\\ce{Ni}$",58.7,1492],["$\\ce{Cu}$",63.5,1083]],"caption":"Book's table, p.12 (for illustration only)","headers":["Element","Atomic mass","Melting point (°C)"]},"children":[]}}},"choices":[{"id":"a","text":"Atomic mass does not decide the melting point; bond strength does.","correct":true},{"id":"b","text":"Heavier atoms melt higher, so iron's value must be a misprint.","correct":false,"misconception_id":"te.high-melting-points.mc1"},{"id":"c","text":"Iron's 3d electrons do not share in its metallic bond.","correct":false,"misconception_id":"te.high-melting-points.mc2"},{"id":"d","text":"Melting point falls steadily with increasing atomic number.","correct":false}],"book_ref":"Ch.1 general properties, point 3b + data table, pp.12-13","difficulty":4,"concept_ids":["te.high-melting-points"],"est_seconds":80},"layer":{"choices":{"a":{"why":"Right. Iron is heavier than vanadium, yet it melts lower."},"b":{"why":"Iron is heavier than vanadium, yet it melts lower: the data is right, and the idea that heavier atoms melt higher is wrong.","feedback":"Misconception: High melting points are due to heavy atoms."},"c":{"why":"The book says both 4s and 3d electrons share in the bond in these elements, and it makes no exception for iron.","feedback":"Misconception: Only the 4s electrons form the metallic bond in some of these metals."},"d":{"why":"The melting point does not fall at every step: it rises from Sc to Cr, then varies.","feedback":"Misconception: Generalizes one pair of elements into a steady trend."}},"explanation":"Vanadium: atomic mass 51, melting point 1710 °C. Iron: atomic mass 55.9, melting point 1538 °C. Iron is heavier but melts lower. So atomic mass does not decide the melting point. The strength of the metallic bond decides it. The book: both 4s and 3d electrons share in this strong bond. The values do not change steadily: they rise from Sc to Cr, then vary."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ iron أتقل من الـ vanadium، ومع ذلك بينصهر عند درجة أقل."},"b":{"why":"الـ iron أتقل من الـ vanadium، ومع ذلك بينصهر عند درجة أقل: الأرقام صح، والفكرة إن الذرات الأتقل بتنصهر عند درجة أعلى هي الغلط.","feedback":"الفكرة الغلط: إن الـ melting points العالية سببها إن الذرات تقيلة."},"c":{"why":"الكتاب بيقول إن الـ 4s والـ 3d electrons الاتنين بيشاركوا في الـ bond في العناصر دي، ومش بيستثني الـ iron.","feedback":"الفكرة الغلط: إن في بعض الـ metals دي الـ 4s electrons لوحدها هي اللي بتعمل الـ metallic bond."},"d":{"why":"الـ melting point مش بيقل في كل خطوة: بيزيد من الـ Sc لحد الـ Cr، وبعدين بيتغيّر.","feedback":"الفكرة الغلط: إنك تعمّم اللي شفته في زوج واحد من العناصر وتعمله اتجاه ثابت."}},"explanation":"الـ vanadium: الكتلة الذرية 51، والـ melting point هي 1710 °C. الـ iron: الكتلة الذرية 55.9، والـ melting point هي 1538 °C. يعني الـ iron أتقل لكنه بينصهر عند درجة أقل. فالكتلة الذرية مش هي اللي بتحدد الـ melting point؛ اللي بيحددها هو قوة الـ metallic bond. والكتاب بيقول: الـ 4s والـ 3d electrons الاتنين بيشاركوا في الـ bond القوي ده. والقيم مابتتغيرش بانتظام: بتعلى من الـ Sc للـ Cr، وبعدين بتتغير طلوع ونزول."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":31,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.table","section_title":"Data table (atomic mass, radius, density, melting and boiling points)","section_path":["Transition Elements","The general properties of the first transition elements","Data table (atomic mass, radius, density, melting and boiling points)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.density-trend-2","kind":"question","version":1,"ord":280,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.density-trend","concepts":[{"concept_id":"te.density-trend","role":"primary"}],"title":"chem-s3-en.question-te.density-trend-2","payload":{"stem":"The table gives the atomic mass and atomic radius of four elements. Without the density column, which element has the highest density?","tags":["exam-style","data","choose"],"type":"mcq","bloom":"analyze","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["$\\ce{Ti}$",47.9,1.32],["$\\ce{Mn}$",54.9,1.17],["$\\ce{Fe}$",55.9,1.16],["$\\ce{Co}$",58.9,1.16]],"caption":"Book's table, p.12 (for illustration only); density column hidden","headers":["Element","Atomic mass","Atomic radius"]},"children":[]}}},"choices":[{"id":"a","text":"Ti","correct":false},{"id":"b","text":"Fe","correct":false},{"id":"c","text":"Co","correct":true},{"id":"d","text":"Mn, Fe and Co equally","correct":false}],"book_ref":"Ch.1 general properties, point 3c + data table, pp.12-13","difficulty":4,"concept_ids":["te.density-trend"],"est_seconds":80},"layer":{"choices":{"a":{"why":"Titanium's atoms are the largest here, and a bigger atom puts less mass into each cm³; its atomic mass is also smaller.","feedback":"Misconception: A larger atom holds more matter, so it is denser."},"b":{"why":"Iron feels heavy in daily life, but its atomic mass is not the largest here, and its atoms are nearly the same size as Mn's and Co's.","feedback":"Misconception: Iron is the familiar 'heavy' metal, so it must be the densest."},"c":{"why":"Right. Same size as Mn and Fe, but the largest mass of the four."},"d":{"why":"Equal size fixes the volume per atom, but the mass per atom is not equal for the three, so their densities differ.","feedback":"Misconception: Atoms of the same size give the same density."}},"explanation":"Density = mass ÷ volume. Atoms of nearly equal radius take nearly the same volume. Mn, Fe and Co have nearly equal radii (1.16 to 1.17). Among them, Co has the largest atomic mass, 58.9. So Co packs the most mass into about the same volume. Ti has larger atoms (1.32) and a smaller mass, so it is the least dense. Book values: Ti 4.42, Mn 7.21, Fe 7.87, Co 8.70 g/cm³."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"ذرات الـ Ti هي الأكبر هنا، والذرة الأكبر بتحط mass أقل في كل cm³؛ وكمان الـ atomic mass بتاعه أصغر.","feedback":"الفكرة الغلط: إن الذرة الأكبر بتشيل مادة أكتر، فتبقى denser."},"b":{"why":"الـ iron بيبان تقيل في الحياة اليومية، لكن الـ atomic mass بتاعه مش الأكبر هنا، وذراته تقريبًا نفس حجم ذرات الـ Mn والـ Co.","feedback":"الفكرة الغلط: إن الـ iron هو الـ metal 'التقيل' اللي كلنا عارفينه، فلازم يكون الأعلى في الـ density."},"c":{"why":"صح. نفس حجم الـ Mn والـ Fe، لكن الـ mass بتاعه الأكبر في الأربعة."},"d":{"why":"الحجم المتساوي بيثبّت الـ volume لكل ذرة، لكن الـ mass لكل ذرة مش متساوي في التلاتة، فالـ density بتاعتهم مختلفة.","feedback":"الفكرة الغلط: إن الذرات اللي ليها نفس الحجم بتدي نفس الـ density."}},"explanation":"Density = mass ÷ volume. الذرات اللي الـ radius بتاعها تقريبًا متساوي بتاخد تقريبًا نفس الـ volume. والـ Mn والـ Fe والـ Co الـ radii بتاعتهم تقريبًا متساوية (من 1.16 لـ 1.17). وأكبر atomic mass فيهم بتاع الـ Co، وهو 58.9. يعني الـ Co بيحط أكبر mass في نفس الحجم تقريبًا. أما الـ Ti فذراته أكبر (1.32) والـ mass بتاعه أصغر، فهو الأقل في الـ density. قيم الكتاب: Ti 4.42، Mn 7.21، Fe 7.87، Co 8.70 g/cm³."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":32,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.table","section_title":"Data table (atomic mass, radius, density, melting and boiling points)","section_path":["Transition Elements","The general properties of the first transition elements","Data table (atomic mass, radius, density, melting and boiling points)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.atomic-mass-trend-3","kind":"question","version":1,"ord":281,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.atomic-mass-trend","concepts":[{"concept_id":"te.atomic-mass-trend","role":"primary"},{"concept_id":"atom.isotopes","role":"secondary"}],"title":"chem-s3-en.question-te.atomic-mass-trend-3","payload":{"stem":"In a laboratory, a sample of nickel is made only of nickel-60 atoms. Cobalt's atomic mass is 58.9. What is true about the atomic mass of this nickel sample?","tags":["exam-style","choose","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"It is about 60, greater than cobalt's","correct":true},{"id":"b","text":"It is 58.7, as nickel always has this mass","correct":false},{"id":"c","text":"It is less than cobalt's, as nickel is abnormal","correct":false},{"id":"d","text":"It cannot be found without the number of protons","correct":false}],"book_ref":"Ch.1 general properties, point 1, p.12","difficulty":4,"concept_ids":["te.atomic-mass-trend","atom.isotopes"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right. With one isotope only, the average is that isotope's mass."},"b":{"why":"58.7 is an average over nickel's natural mix of isotopes, and this sample is not that mix.","feedback":"Misconception: Nickel's 58.7 is a fixed property of the element, not an average of its isotopes."},"c":{"why":"Nickel is abnormal because of its isotope mix. With one isotope present, the average is that isotope's mass.","feedback":"Misconception: Nickel is abnormal by nature, whatever isotopes the sample contains."},"d":{"why":"All nickel atoms have 28 protons. The number 60 in nickel-60 gives the mass of the isotope.","feedback":"Misconception: Atomic mass is decided by the number of protons only."}},"explanation":"Natural nickel is a mix of five stable isotopes. Its atomic mass, 58.7 u, is their average. Most natural nickel atoms are the light nickel-58, so the average is below cobalt's 58.9. This sample has only nickel-60 atoms. So its average mass is about 60, greater than cobalt's. Nickel's abnormality comes from its isotope mix, not from its protons."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: لما يكون فيه isotope واحد لوحده، المتوسط بيبقى هو كتلة الـ isotope ده."},"b":{"why":"الـ 58.7 دي متوسط لخليط الـ isotopes الطبيعي بتاع الـ nickel، والعينة دي مش نفس الخليط ده.","feedback":"الفكرة الغلط: إن الـ 58.7 بتاعة الـ nickel صفة ثابتة للعنصر، مش متوسط الـ isotopes بتاعته."},"c":{"why":"الـ nickel شاذ بسبب خليط الـ isotopes بتاعه. ولما يكون فيه isotope واحد لوحده، المتوسط بيبقى هو كتلة الـ isotope ده.","feedback":"الفكرة الغلط: إن الـ nickel شاذ بطبيعته، مهما كانت الـ isotopes اللي في العينة."},"d":{"why":"كل ذرات الـ nickel فيها 28 protons. والرقم 60 في nickel-60 بيديك كتلة الـ isotope.","feedback":"الفكرة الغلط: إن الـ atomic mass بيتحدد بعدد الـ protons لوحده."}},"explanation":"الـ nickel الطبيعي خليط من خمس isotopes مستقرة. والـ atomic mass بتاعه، 58.7 u، هو متوسطهم. وأغلب ذرات الـ nickel الطبيعي هي الـ nickel-58 الخفيفة، فالمتوسط بيطلع أقل من الـ 58.9 بتاعة الـ cobalt. العينة دي مفيش فيها غير ذرات nickel-60. يبقى متوسط كتلتها حوالي 60، أكبر من الـ cobalt. وشذوذ الـ nickel جاي من خليط الـ isotopes بتاعه، مش من الـ protons بتوعه."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":33,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.mass","section_title":"The atomic mass","section_path":["Transition Elements","The general properties of the first transition elements","The atomic mass"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.atomic-radius-3","kind":"question","version":1,"ord":282,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.atomic-radius","concepts":[{"concept_id":"te.atomic-radius","role":"primary"}],"title":"chem-s3-en.question-te.atomic-radius-3","payload":{"stem":"Consider the following statements about the atomic radius in the first transition series:\n(I) The effective nuclear charge increases, which tends to decrease the atomic radius.\n(II) The repulsion between 3d electrons increases with their number, which tends to decrease the atomic radius.\n(III) The two factors oppose each other, so the atomic radius is nearly constant from Cr to Cu.\nWhich of these statements is/are correct?","tags":["exam-style","statements-I-II-III"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"(I) only","correct":false},{"id":"b","text":"(I) and (II)","correct":false},{"id":"c","text":"(I) and (III)","correct":true},{"id":"d","text":"(II) and (III)","correct":false}],"book_ref":"Ch.1 general properties, point 2, pp.12-13","difficulty":3,"concept_ids":["te.atomic-radius"],"est_seconds":75},"layer":{"choices":{"a":{"why":"If (I) alone were true, the atoms would keep shrinking, but the book's table shows a nearly constant radius from Cr to Cu.","feedback":"Misconception: Only the nuclear charge matters; ignores the balancing factor."},"b":{"why":"Electrons that repel each other push apart, which makes the atom larger, so (II) is wrong.","feedback":"Misconception: Repulsion between electrons also shrinks the atom."},"c":{"why":"Right. Statement (II) gives the wrong direction for the repulsion."},"d":{"why":"Each element has one more proton than the one before, so the pull on the electrons rises: (I) is correct.","feedback":"Misconception: The effective nuclear charge does not increase across the series."}},"explanation":"(I) is correct. The effective nuclear charge increases, so the nuclear attraction to electrons increases. This decreases the radius. (II) is wrong. More 3d electrons repel each other more, which increases the radius, not decreases it. (III) is correct. The two opposite factors balance, so the radius is nearly constant from Cr to Cu."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"لو (I) لوحدها اللي صح، الذرات كانت هتفضل تصغر، لكن جدول الكتاب بيوري radius ثابت تقريبًا من الـ Cr للـ Cu.","feedback":"الفكرة الغلط: إن الـ nuclear charge هي العامل الوحيد، ونسيان العامل اللي بيوازنها."},"b":{"why":"الـ electrons اللي بتتنافر بتزق بعضها بعيد، وده بيخلّي الذرة أكبر، فـ (II) غلط.","feedback":"الفكرة الغلط: إن التنافر بين الـ electrons هو كمان بيصغّر الذرة."},"c":{"why":"صح. العبارة (II) بتدّي اتجاه غلط لتأثير التنافر."},"d":{"why":"كل عنصر عنده proton زيادة عن اللي قبله، فالشدّ على الـ electrons بيزيد: (I) صح.","feedback":"الفكرة الغلط: إن الـ effective nuclear charge مابتزيدش على طول السلسلة."}},"explanation":"(I) صح: الـ effective nuclear charge بتزيد، فالـ nuclear attraction للـ electrons بتزيد، وده بيصغّر الـ radius. (II) غلط: الـ 3d electrons لما تكتر بتتنافر أكتر، وده بيكبّر الـ radius مش بيصغّره. (III) صح: العاملين العكسيين بيوازنوا بعض، فالـ radius ثابت تقريبًا من الـ Cr للـ Cu."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":34,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.metallic-properties-3","kind":"question","version":2,"ord":283,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.metallic-properties","concepts":[{"concept_id":"te.metallic-properties","role":"primary"},{"concept_id":"te.electron-configuration","role":"secondary"}],"title":"chem-s3-en.question-te.metallic-properties-3","payload":{"stem":"Element X is in the first transition series. Its atom has the electronic configuration [Ar] $4s^2\\,3d^1$. Which describes the chemical activity of X?","tags":["exam-style","two-step","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Limited activity, like copper","correct":false,"misconception_id":"te.metallic-properties.mc1"},{"id":"b","text":"Moderate activity: it goes rusty in air, like iron","correct":false},{"id":"c","text":"High activity: it replaces the hydrogen of water strongly","correct":true},{"id":"d","text":"No activity, since its 3d sublevel is almost empty","correct":false}],"book_ref":"Ch.1 general properties, point 3d, p.13; configurations p.8","difficulty":3,"concept_ids":["te.metallic-properties","te.electron-configuration"],"est_seconds":70},"layer":{"choices":{"a":{"why":"X is not copper ([Ar] $4s^1\\,3d^{10}$): it has one 3d electron, so X is scandium, which the book calls highly active.","feedback":"Misconception: Misidentifies X as copper, or assumes all transition metals are unreactive."},"b":{"why":"Iron has six 3d electrons; X has one, so X is scandium, and the book calls scandium highly active, not moderate like iron.","feedback":"Misconception: Assumes every transition metal behaves like iron."},"c":{"why":"Right. X is scandium, the highly active member in the book."},"d":{"why":"The book does not link activity to an empty 3d. X, with one 3d electron, is scandium, and the book calls it highly active.","feedback":"Misconception: Chemical activity depends on how full the 3d sublevel is."}},"explanation":"Step 1: name X. [Ar] $4s^2\\,3d^1$ has one 3d electron, so X is the first element, scandium (Z = 21). Step 2: recall its activity. The book says scandium is highly active: it replaces the hydrogen of water strongly. Activity varies across the series: copper limited, iron moderate, scandium highly active."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"الـ copper هو [Ar] $4s^1\\,3d^{10}$، والـ X فيه 3d electron واحد، فالـ X مش الـ copper ونشاطه مش limited.","feedback":"الفكرة الغلط: إنك فاكر X هو الـ copper، أو إن كل الـ transition metals مش نشيطة."},"b":{"why":"الـ iron فيه 3d electrons عددهم ستة؛ والـ X فيه واحد، فالـ X هو الـ scandium، والكتاب بيقول إنه highly active، مش moderate زي الـ iron.","feedback":"الفكرة الغلط: إن كل transition metal بيتصرف زي الـ iron."},"c":{"why":"صح. الـ X هو الـ scandium، العنصر اللي الكتاب بيقول إنه highly active."},"d":{"why":"الكتاب مش بيربط النشاط بإن الـ 3d فاضي. الـ configuration دي بتاعة الـ scandium، والكتاب بيقول إنه highly active.","feedback":"الفكرة الغلط: إن الـ chemical activity بتعتمد على الـ 3d sublevel مليان قد إيه."}},"explanation":"خطوة 1: اعرف X. الـ [Ar] $4s^2\\,3d^1$ فيها 3d electron واحد، يبقى X هو أول عنصر، الـ scandium (Z = 21). خطوة 2: افتكر نشاطه. الكتاب بيقول إن الـ scandium highly active: بيحل محل الـ hydrogen of water بقوة. النشاط بيختلف على طول السلسلة: الـ copper نشاطه limited، والـ iron نشاطه moderate، والـ scandium highly active."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":35,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.high-melting-points-3","kind":"question","version":1,"ord":284,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.high-melting-points","concepts":[{"concept_id":"te.high-melting-points","role":"primary"}],"title":"chem-s3-en.question-te.high-melting-points-3","payload":{"stem":"Vanadium ($_{23}$V) has the configuration [Ar] $4s^2\\,3d^3$. Using the book's reason for high melting points, how many electrons of each vanadium atom can share in the metallic bond?","tags":["exam-style","choose","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"2","correct":false,"misconception_id":"te.high-melting-points.mc2"},{"id":"b","text":"3","correct":false},{"id":"c","text":"5","correct":true},{"id":"d","text":"23","correct":false}],"book_ref":"Ch.1 general properties, point 3b, p.13","difficulty":3,"concept_ids":["te.high-melting-points"],"est_seconds":60},"layer":{"choices":{"a":{"why":"That counts the 4s electrons only; the book names the 3d electrons for the bond too.","feedback":"Misconception: Only the 4s electrons form the metallic bond."},"b":{"why":"That counts the 3d electrons only and leaves out the outer 4s sublevel.","feedback":"Misconception: Only the d electrons form the bond in a transition metal."},"c":{"why":"Right. Both sublevels count: 2 electrons in 4s and 3 in 3d."},"d":{"why":"The inner [Ar] electrons stay close to the nucleus and do not take part; the book names the 4s and 3d sublevels for the bond.","feedback":"Misconception: All electrons of the atom join the metallic bond."}},"explanation":"The book: the strong metallic bond forms by the sharing of both 4s and 3d electrons. Vanadium has 2 electrons in 4s and 3 in 3d. So 2 + 3 = 5 electrons per atom can share in the bond. The inner [Ar] electrons do not take part. Calcium, [Ar] $4s^2$, has only its two 4s electrons. That is why vanadium's metallic bond is much stronger."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"كده إنت عدّيت الـ 4s electrons لوحدها؛ الكتاب بيذكر الـ 3d electrons كمان للـ bond.","feedback":"الفكرة الغلط: إن الـ 4s electrons لوحدها هي اللي بتعمل الـ metallic bond."},"b":{"why":"كده إنت عدّيت الـ 3d electrons لوحدها وسبت الـ 4s sublevel الخارجي.","feedback":"الفكرة الغلط: إن في الـ transition metal الـ d electrons لوحدها هي اللي بتعمل الـ bond."},"c":{"why":"صح. الـ sublevels الاتنين بيتحسبوا: 2 electrons في الـ 4s و3 في الـ 3d."},"d":{"why":"الـ electrons الداخلية بتوع الـ [Ar] بتفضل قريبة من الـ nucleus ومش بتشارك؛ الكتاب بيذكر الـ 4s والـ 3d sublevels للـ bond.","feedback":"الفكرة الغلط: إن كل electrons الذرة بتدخل في الـ metallic bond."}},"explanation":"الكتاب بيقول: الـ metallic bond القوي بيتكوّن من مشاركة الـ 4s والـ 3d electrons الاتنين. الـ vanadium عنده 2 electrons في الـ 4s و3 في الـ 3d. يعني 2 + 3 = 5 electrons من كل ذرة ممكن يشاركوا في الـ bond. أما الـ electrons الداخلية بتاعة الـ [Ar] فمابتشاركش. والـ calcium، [Ar] $4s^2$، عنده الـ 2 electrons بتوع الـ 4s تحديدًا. وعشان كده الـ metallic bond بتاع الـ vanadium أقوى بكتير."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":36,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.density-trend-3","kind":"question","version":1,"ord":285,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.density-trend","concepts":[{"concept_id":"te.density-trend","role":"primary"}],"title":"chem-s3-en.question-te.density-trend-3","payload":{"stem":"From Sc to Ti, the atomic mass rises by only about 6%, but the density rises by about 43%. Use the table. Which statement explains the large rise?","tags":["exam-style","data","choose","new-case"],"type":"mcq","bloom":"analyze","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["$\\ce{Sc}$",45,1.44,"3.10"],["$\\ce{Ti}$",47.9,1.32,"4.42"]],"caption":"Book's table, p.12 (for illustration only)","headers":["Element","Atomic mass","Atomic radius","Density (g/cm³)"]},"children":[]}}},"choices":[{"id":"a","text":"The mass rises and the radius falls; both raise the density.","correct":true},{"id":"b","text":"The rise in atomic mass alone explains the rise.","correct":false},{"id":"c","text":"Titanium atoms are larger, so each holds more mass.","correct":false},{"id":"d","text":"Titanium melts higher, so its atoms pack more mass.","correct":false}],"book_ref":"Ch.1 general properties, point 3c + data table, pp.12-13","difficulty":5,"concept_ids":["te.density-trend"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right. More mass and a smaller volume per atom both push the density up."},"b":{"why":"A 6% rise in mass cannot give a 43% rise on its own; the atoms also got smaller, from 1.44 to 1.32.","feedback":"Misconception: Density depends on mass only; the volume is ignored."},"c":{"why":"Titanium atoms are smaller than scandium atoms (1.32 against 1.44), not larger.","feedback":"Misconception: Bigger atoms are denser (or the radius column is misread)."},"d":{"why":"Melting point tells you about bond strength, not mass per volume; density depends on mass and volume.","feedback":"Misconception: A higher melting point means a higher density."}},"explanation":"Density = mass ÷ volume. From Sc to Ti, the atomic mass rises from 45 to 47.9. The atomic radius also falls, from 1.44 to 1.32. So each atom has more mass in a smaller volume. Both changes raise the density, from 3.10 to 4.42 g/cm³. From Cr to Cu, the radius is nearly constant. There, the rising atomic mass is the main reason."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. mass أكتر و volume أصغر لكل ذرة، والاتنين بيزقّوا الـ density لفوق."},"b":{"why":"زيادة 6% في الـ mass لوحدها ماتقدرش تدي زيادة 43%؛ الذرات كمان صغرت، من 1.44 لـ 1.32.","feedback":"الفكرة الغلط: إن الـ density بتعتمد على الـ mass لوحده، والـ volume مش داخل في الحساب."},"c":{"why":"ذرات الـ titanium أصغر من ذرات الـ scandium (1.32 قصاد 1.44)، مش أكبر.","feedback":"الفكرة الغلط: إن الذرات الأكبر بتبقى denser (أو إن عمود الـ radius اتقرا غلط)."},"d":{"why":"الـ melting point بيقولك على قوة الروابط، مش على الـ mass في كل volume؛ الـ density بتعتمد على الـ mass والـ volume.","feedback":"الفكرة الغلط: إن الـ melting point الأعلى معناه density أعلى."}},"explanation":"Density = mass ÷ volume. من الـ Sc للـ Ti، الـ atomic mass بيزيد من 45 لـ 47.9، والـ atomic radius كمان بيقل من 1.44 لـ 1.32. يعني كل ذرة فيها mass أكتر في volume أصغر. والتغييرين الاتنين بيرفعوا الـ density، من 3.10 لـ 4.42 g/cm³. أما من الـ Cr للـ Cu، فالـ radius تقريبًا ثابت، وهناك الـ atomic mass اللي بيزيد هو السبب الأساسي."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":37,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.table","section_title":"Data table (atomic mass, radius, density, melting and boiling points)","section_path":["Transition Elements","The general properties of the first transition elements","Data table (atomic mass, radius, density, melting and boiling points)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.metallic","section_title":"The Metallic property","section_path":["Transition Elements","The general properties of the first transition elements","The Metallic property"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.atomic-radius-4","kind":"question","version":1,"ord":286,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.atomic-radius","concepts":[{"concept_id":"te.atomic-radius","role":"primary"}],"title":"chem-s3-en.question-te.atomic-radius-4","payload":{"stem":"Manganese ($_{25}$Mn) and copper ($_{29}$Cu) have the same atomic radius in the book's table (1.17), although copper has four more protons. Which statement explains this?","tags":["exam-style","choose","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"The nuclear attraction stays the same from Mn to Cu.","correct":false},{"id":"b","text":"More 3d repulsion in Cu balances its greater nuclear attraction.","correct":true},{"id":"c","text":"Copper has only one 4s electron, which stops its atom shrinking.","correct":false},{"id":"d","text":"Copper atoms are heavier, so they take up more space.","correct":false}],"book_ref":"Ch.1 general properties, point 2 + data table, pp.12-13","difficulty":3,"concept_ids":["te.atomic-radius"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Copper has four more protons than manganese, so the pull on the electrons increases.","feedback":"Misconception: The effective nuclear charge does not change in this part of the series."},"b":{"why":"Right. Cu has 3d$^{10}$ and Mn 3d$^5$: more repulsion balances the stronger pull."},"c":{"why":"Copper's 4s¹ explains its configuration, not its size. The book uses two factors for size: nuclear attraction and 3d repulsion.","feedback":"Misconception: Mixes up the abnormal configuration of copper with the radius trend."},"d":{"why":"Most of the mass is in the tiny nucleus, and a heavier nucleus does not make the atom larger. The book's two factors decide the size.","feedback":"Misconception: Heavier atoms are bigger."}},"explanation":"From Mn to Cu, the effective nuclear charge increases, so the nuclear attraction increases. Alone, this would shrink the atom. But the 3d electrons also increase, from 3d$^5$ in Mn to 3d$^{10}$ in Cu. Their repulsion increases, which tends to enlarge the atom. The two opposite factors balance, so Cu's radius is again 1.17, the same as Mn's. (The elements between them are only slightly smaller.) Copper's 4s¹ and its mass are not the book's reasons for size."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"الـ copper عنده 4 protons أكتر من الـ manganese، فالشدّ على الـ electrons بيزيد.","feedback":"الفكرة الغلط: إن الـ effective nuclear charge مابتتغيّرش في الجزء ده من السلسلة."},"b":{"why":"صح. الـ Cu عنده 3d$^{10}$ والـ Mn عنده 3d$^5$: التنافر الأكتر بيوازن الشدّ الأقوى."},"c":{"why":"الـ 4s¹ بتاع الـ copper بيفسّر الـ configuration بتاعته، مش حجمه. الكتاب بيستخدم عاملين لحجم الذرة: شدّ الـ nucleus وتنافر الـ 3d electrons.","feedback":"الفكرة الغلط: الخلط بين الـ abnormal configuration بتاعة الـ copper وتغيّر الـ radius."},"d":{"why":"معظم الكتلة موجودة في الـ nucleus الصغيرة جدًا، والـ nucleus الأتقل مابتكبّرش الذرة. العاملين بتوع الكتاب هما اللي بيحددوا الحجم.","feedback":"الفكرة الغلط: إن الذرات الأتقل أكبر."}},"explanation":"من الـ Mn للـ Cu، الـ effective nuclear charge بتزيد، فالـ nuclear attraction بتزيد. لو ده لوحده، الذرة كانت هتصغر. لكن الـ 3d electrons كمان بتزيد، من 3d$^5$ في الـ Mn لـ 3d$^{10}$ في الـ Cu، والتنافر بينهم بيزيد، وده بيميل يكبّر الذرة. العاملين العكسيين بيوازنوا بعض، فالـ radius بتاع الـ Cu بيرجع 1.17، زي الـ Mn. (العناصر اللي بينهم أصغر يدوب شوية.) الـ 4s¹ بتاع الـ copper وكتلته مش من أسباب الحجم في الكتاب."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":38,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.ion-configuration-5","kind":"question","version":1,"ord":287,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.ion-configuration","concepts":[{"concept_id":"te.ion-configuration","role":"primary"}],"title":"chem-s3-en.question-te.ion-configuration-5","payload":{"stem":"Write the electronic configuration of: (a) $\\ce{Cr^3+}$ ($_{24}$Cr) (b) $\\ce{Ni^2+}$ ($_{28}$Ni)","tags":["recall","write-configuration"],"type":"short","bloom":"apply","answer":"(a) $\\ce{Cr^3+}$: [Ar] $3d^3$ (from Cr [Ar] $4s^1\\,3d^5$: lose the 4s electron, then two 3d electrons). (b) $\\ce{Ni^2+}$: [Ar] $3d^8$ (from Ni [Ar] $4s^2\\,3d^8$: lose the two 4s electrons).","book_ref":"Ch.1 point 3, p.9","difficulty":3,"concept_ids":["te.ion-configuration"],"est_seconds":90},"layer":{"explanation":"Write the atom first. Then remove electrons from 4s first: 4s is the outer level, so it loses electrons first. (a) Cr is [Ar] $4s^1\\,3d^5$. Remove the one 4s electron, then two 3d electrons: [Ar] $3d^3$. (b) Ni is [Ar] $4s^2\\,3d^8$. Remove the two 4s electrons: [Ar] $3d^8$. Most likely wrong answer: removing 3d electrons first, giving Ni²⁺ as [Ar] $4s^2\\,3d^6$. Another: Cr³⁺ as [Ar] $4s^1\\,3d^2$, keeping the outer 4s electron."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"اكتب الذرة الأول. وبعدين شيل الـ electrons من الـ 4s الأول: الـ 4s هو المستوى الخارجي، فهو اللي بيفقد electrons الأول. (a) الـ Cr هو [Ar] $4s^1\\,3d^5$. شيل الـ 4s electron الوحيد، وبعدين اتنين 3d electrons: [Ar] $3d^3$. (b) الـ Ni هو [Ar] $4s^2\\,3d^8$. شيل الاتنين 4s electrons: [Ar] $3d^8$. أشهر إجابة غلط: إنك تشيل 3d electrons الأول، فيطلع معاك Ni²⁺ = [Ar] $4s^2\\,3d^6$. وغلطة تانية: Cr³⁺ = [Ar] $4s^1\\,3d^2$، يعني سبت الـ 4s electron الخارجي."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":69,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.cr-cu-anomaly-5","kind":"question","version":1,"ord":288,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.cr-cu-anomaly","concepts":[{"concept_id":"te.cr-cu-anomaly","role":"primary"}],"title":"chem-s3-en.question-te.cr-cu-anomaly-5","payload":{"stem":"Give reasons: The electronic configuration of copper ($_{29}$Cu) is abnormal.","tags":["recall","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) The expected configuration is [Ar] $4s^2\\,3d^9$. (2) The real one is [Ar] $4s^1\\,3d^{10}$: one electron is in 3d instead of 4s. (3) A completely filled 3d sublevel ($d^{10}$) gives the atom lower energy and extra stability.","book_ref":"Ch.1 point 2, pp.8-9; Evaluation Q7.1, p.27","difficulty":2,"concept_ids":["te.cr-cu-anomaly"],"est_seconds":75},"layer":{"explanation":"By the filling pattern, copper would be [Ar] $4s^2\\,3d^9$. But the real atom is [Ar] $4s^1\\,3d^{10}$. Now the 3d sublevel is completely filled ($d^{10}$), and 4s is half filled. This arrangement gives the atom lower energy, so it is more stable. Chromium is abnormal for a similar reason: half-filled 3d ($d^5$). Key words: abnormal configuration, filled $d^{10}$, extra stability. Most likely wrong answer: writing [Ar] $4s^2\\,3d^9$ and calling it normal."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"لو مشينا بترتيب الملء، الـ copper المفروض يبقى [Ar] $4s^2\\,3d^9$. لكن الذرة الحقيقية توزيعها [Ar] $4s^1\\,3d^{10}$. كده الـ 3d sublevel بقى completely filled ($d^{10}$)، والـ 4s بقى half filled. الترتيب ده بيدّي الذرة lower energy، فبتبقى أكتر استقرارًا. والـ chromium هو كمان abnormal لسبب شبه ده: الـ 3d بتاعه half-filled ($d^5$). الكلمات المفتاحية: abnormal configuration، filled $d^{10}$، extra stability. أشهر غلطة: إنك تكتب [Ar] $4s^2\\,3d^9$ وتقول إنه طبيعي."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":70,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"1","relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-sc-ti-4","kind":"question","version":2,"ord":289,"group_id":"chem-s3-en.ch1.practice.te-physical-properties","primary_concept_id":"te.uses-sc-ti","concepts":[{"concept_id":"te.uses-sc-ti","role":"primary"}],"title":"chem-s3-en.question-te.uses-sc-ti-4","payload":{"stem":"Element X of the first transition series is as rigid as steel but less dense than steel. Which is a use of X?","tags":["recall","two-step","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Dental implants and artificial joints","correct":true},{"id":"b","text":"Mercury vapour lamps for TV photography at night","correct":false},{"id":"c","text":"Car springs, added in small amounts to steel","correct":false},{"id":"d","text":"Metal plating and leather tanning","correct":false}],"book_ref":"Ch.1 economic importance: 2-Titanium, p.5","difficulty":3,"concept_ids":["te.uses-sc-ti"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right. X is titanium; it is inert, so the body does not reject it."},"b":{"why":"Mercury vapour lamps use scandium; the metal the book calls as rigid as steel but less dense is titanium.","feedback":"Misconception: Mixes up scandium and titanium, the two light metals at the start of the series."},"c":{"why":"'Rigid as steel' describes X itself, not a metal added to steel; car springs use vanadium added to steel.","feedback":"Misconception: Links 'as rigid as steel' to vanadium, which hardens steel."},"d":{"why":"Plating uses chromium, a metal that resists the effect of atmosphere; that is not the property described here.","feedback":"Misconception: Links strength and durability to chromium's uses."}},"explanation":"Step 1: name X. The book says titanium is as rigid as steel but less dense than steel. So X is titanium. Step 2: recall its uses. Titanium is used in dental implants and artificial joints. It is inert, so the body does not reject it. Its alloys with aluminum are used in aircraft and space shuttles. Scandium is used in mercury vapour lamps. A vanadium-steel alloy is used in car springs, and chromium is used in plating."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ X هو الـ titanium، وهو inert، فالجسم مابيرفضوش."},"b":{"why":"الـ mercury vapour lamps بتستخدم metal خفيف تاني، الـ scandium، مش الـ metal اللي الكتاب بيقول عليه جامد زي الـ steel لكن كثافته أقل.","feedback":"الفكرة الغلط: خلط الـ scandium بالـ titanium، الاتنين metals خفاف في أول السلسلة."},"c":{"why":"\"as rigid as steel\" دي وصف للـ X نفسه، مش لـ metal بيتضاف للـ steel. الـ car springs بتستخدم الـ vanadium.","feedback":"الفكرة الغلط: ربط \"as rigid as steel\" بالـ vanadium، اللي بيقوّي الـ steel."},"d":{"why":"الطلاء بيستخدم metal بيقاوم تأثير الجو (effect of atmosphere)، ودي مش الخاصية الموصوفة هنا.","feedback":"الفكرة الغلط: ربط القوة والمتانة باستخدامات الـ chromium."}},"explanation":"الخطوة 1: حدد الـ X. الكتاب بيقول إن الـ titanium جامد زي الـ steel لكن كثافته أقل من الـ steel، يبقى الـ X هو الـ titanium. الخطوة 2: افتكر استخداماته. الـ titanium بيستخدم في زراعة الأسنان والمفاصل الصناعية، لأنه inert فالجسم مابيرفضوش. والـ alloys بتاعته مع الـ aluminum بتستخدم في الطيارات ومكوكات الفضاء. أما الـ scandium فبيستخدم في الـ mercury vapour lamps، والـ alloy بتاع الـ vanadium مع الـ steel بيتعمل منه سوست العربيات، والـ chromium بيستخدم في الطلاء."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":78,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.bond-breaking-energy-1","kind":"question","version":1,"ord":308,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"chem.bond-breaking-energy","concepts":[{"concept_id":"chem.bond-breaking-energy","role":"primary"}],"title":"chem-s3-en.question-chem.bond-breaking-energy-1","payload":{"stem":"Hydrogen reacts with iodine: $\\ce{H2 + I2 -> 2HI}$. Which statement about the energy of the two steps is correct?","tags":["diagnostic","prerequisite","warm-up"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Breaking the H–H and I–I bonds absorbs energy; forming the H–I bonds releases energy.","correct":true},{"id":"b","text":"Breaking the H–H and I–I bonds releases energy; forming the H–I bonds absorbs energy.","correct":false},{"id":"c","text":"Breaking the H–H and I–I bonds absorbs energy; forming the H–I bonds absorbs energy too.","correct":false},{"id":"d","text":"Neither step involves energy, because the same atoms are only rearranged.","correct":false}],"book_ref":"Prerequisite; used in Ch.1 point 5, fig 1-3 (net energy released), p.15","difficulty":2,"concept_ids":["chem.bond-breaking-energy"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right. Pulling bonded atoms apart needs energy; new bonds give energy out."},"b":{"why":"This swaps the two steps. Bonded atoms hold each other, so you must put energy in to pull them apart.","feedback":"Misconception: Breaking bonds releases energy."},"c":{"why":"The first half is fine. But when free atoms join into a bond, they settle down, and energy is given out.","feedback":"Misconception: Every step of a reaction needs energy put in."},"d":{"why":"The atoms do stay the same. But bonds hold atoms with a force, so a bond cannot break or form with no energy change.","feedback":"Misconception: Rearranging atoms involves no energy change."}},"explanation":"A reaction has two steps. First, the bonds in the reactants break: here H–H and I–I. Breaking a bond absorbs energy, because the bonded atoms pull on each other. Then new bonds form in the products: here H–I. Forming a bond releases energy. The balance between the two decides whether the reaction gives out or takes in energy overall. Key words: breaking bonds absorbs energy; forming bonds releases energy."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. فصل الذرات اللي بينها bond محتاج energy، والـ bonds الجديدة بتطلّع energy."},"b":{"why":"كده إنت قلبت الخطوتين. الذرات اللي بينها bond ماسكة في بعض، وعشان تفصلهم لازم تدخّل energy.","feedback":"الفكرة الغلط: إن كسر الـ bonds بيطلّع energy."},"c":{"why":"النص الأول تمام. لكن لما ذرات حرة بتتجمع وتعمل bond، بتستقر، والـ energy ساعتها بتطلع مش بتدخل.","feedback":"الفكرة الغلط: إن كل خطوة في الـ reaction محتاجة energy تدخل لها."},"d":{"why":"الذرات فعلًا هي هي، لكن الـ bonds ماسكة الذرات بقوة، ومفيش bond بيتكسر أو يتكوّن من غير ما الـ energy تتغير.","feedback":"الفكرة الغلط: إن إعادة ترتيب الذرات مالهاش أي تغيير في الـ energy."}},"explanation":"الـ reaction ليه خطوتين. الأول، الـ bonds اللي في الـ reactants بتتكسر: هنا H–H و I–I. كسر الـ bond بيمتص energy، عشان الذرات اللي بينها bond بتشد بعض. بعد كده bonds جديدة بتتكوّن في الـ products: هنا H–I. وتكوين الـ bond بيطلّع energy. والفرق بين الاتنين هو اللي بيحدد الـ reaction في الآخر بيطلّع energy ولا بيمتص energy. الكلمات المهمة: breaking bonds absorbs energy؛ forming bonds releases energy."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":13,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.bond-breaking-energy-2","kind":"question","version":1,"ord":309,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"chem.bond-breaking-energy","concepts":[{"concept_id":"chem.bond-breaking-energy","role":"primary"}],"title":"chem-s3-en.question-chem.bond-breaking-energy-2","payload":{"stem":"In a reaction, breaking all the bonds in the reactants absorbs 680 kJ. Forming all the bonds in the products releases 860 kJ. Which describes the reaction?","tags":["diagnostic","prerequisite","new-case","calculation"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"It gives out 180 kJ of energy overall.","correct":true},{"id":"b","text":"It takes in 180 kJ of energy overall.","correct":false},{"id":"c","text":"It gives out 1540 kJ of energy overall.","correct":false},{"id":"d","text":"It takes in 680 kJ of energy overall.","correct":false}],"book_ref":"Prerequisite; used in Ch.1 point 5, fig 1-3 (net energy released), p.15","difficulty":3,"concept_ids":["chem.bond-breaking-energy"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right. More energy comes out (860 kJ) than goes in (680 kJ)."},"b":{"why":"The size is right, but the energy going out (860 kJ) is larger than the energy going in (680 kJ).","feedback":"Misconception: Mixes up the direction of the net energy change."},"c":{"why":"You added the two numbers. One is energy in and one is energy out, so they should be subtracted, not added.","feedback":"Misconception: Adds energy absorbed and energy released."},"d":{"why":"That counts only the breaking step. Forming the new bonds releases 860 kJ, and that energy counts too.","feedback":"Misconception: Only bond breaking counts toward the reaction's energy."}},"explanation":"Breaking bonds absorbs energy: 680 kJ goes in. Forming bonds releases energy: 860 kJ comes out. Net = released − absorbed = 860 − 680 = 180 kJ. More energy is released than absorbed, so the reaction gives out 180 kJ. In an energy profile, the products are then lower than the reactants. This difference is the net energy released (book fig 1-3)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ energy اللي طالعة (860 kJ) أكتر من اللي داخلة (680 kJ)."},"b":{"why":"المقدار صح، لكن الـ energy الطالعة (860 kJ) أكبر من الـ energy الداخلة (680 kJ)، فالـ reaction مش بيمتص.","feedback":"الفكرة الغلط: إنك تلخبط في اتجاه التغيير الصافي في الـ energy."},"c":{"why":"إنت جمعت الرقمين، وواحد فيهم energy داخلة والتاني energy طالعة، فمينفعش نجمعهم؛ الصافي هو الفرق بينهم.","feedback":"الفكرة الغلط: إنك تجمع الـ energy الممتصة على الـ energy اللي طلعت."},"d":{"why":"كده إنت حسبت خطوة الكسر لوحدها، ونسيت إن الـ bonds الجديدة لما تتكوّن بتطلّع energy.","feedback":"الفكرة الغلط: إن كسر الـ bonds لوحده هو اللي بيتحسب في energy الـ reaction."}},"explanation":"كسر الـ bonds بيمتص energy: يعني 680 kJ داخلين. وتكوين الـ bonds بيطلّع energy: يعني 860 kJ طالعين. الصافي = released − absorbed = 860 − 680 = 180 kJ. الـ energy اللي طلعت أكتر من اللي اتمصت، يبقى الـ reaction بيطلّع 180 kJ. وفي الـ energy profile، الـ products ساعتها بتبقى أوطى من الـ reactants. الفرق ده هو الـ net energy released (شكل 1-3 في الكتاب)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":14,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-kin.activation-energy-1","kind":"question","version":1,"ord":310,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"kin.activation-energy","concepts":[{"concept_id":"kin.activation-energy","role":"primary"}],"title":"chem-s3-en.question-kin.activation-energy-1","payload":{"stem":"Which statement describes the activation energy of a reaction?","tags":["diagnostic","prerequisite","warm-up"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"The minimum energy colliding molecules must have to react.","correct":true},{"id":"b","text":"The energy given out by the reaction when products form.","correct":false,"misconception_id":"kin.activation-energy.mc1"},{"id":"c","text":"The extra energy that a catalyst adds to the molecules.","correct":false},{"id":"d","text":"The total energy stored in the product molecules.","correct":false}],"book_ref":"Ch.3 activation energy, pp.61-62 (met first in Ch.1 point 5, fig 1-3, p.15)","difficulty":2,"concept_ids":["kin.activation-energy"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right. Below it, colliding molecules just bounce apart."},"b":{"why":"That is the net energy released: the drop from reactants to products. Activation energy is a climb, not a drop.","feedback":"Misconception: Activation energy is the energy released by the reaction."},"c":{"why":"A catalyst does not add energy to molecules. It changes the barrier, and that barrier is the activation energy.","feedback":"Misconception: A catalyst supplies energy to the reacting molecules."},"d":{"why":"That is just the products' level on the profile. Activation energy is measured from the reactants up to the top of the hump.","feedback":"Misconception: Activation energy is the energy level of the products."}},"explanation":"Molecules react only when they collide with enough energy to break their bonds. The activation energy is the minimum energy that must be gained by a molecule to react at collision. On an energy profile it is the climb from the reactants up to the top of the hump. It is not the energy released (the drop from reactants to products), and a catalyst does not add energy."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. لو الـ energy أقل منها، الجزيئات اللي بتتصادم بتخبط في بعض وترتد وخلاص."},"b":{"why":"دي صافي الـ energy اللي بتطلع: النزلة من الـ reactants للـ products. الـ activation energy طلعة، مش نزلة.","feedback":"الفكرة الغلط: إن الـ activation energy هي الـ energy اللي الـ reaction بيطلّعها."},"c":{"why":"الـ catalyst مش بيزوّد energy للجزيئات؛ هو بيغيّر الحاجز، والحاجز ده هو الـ activation energy.","feedback":"الفكرة الغلط: إن الـ catalyst بيدّي energy للجزيئات اللي بتتفاعل."},"d":{"why":"ده مجرد مستوى الـ products على الـ profile. الـ activation energy بتتقاس من الـ reactants لحد قمة الحدبة.","feedback":"الفكرة الغلط: إن الـ activation energy هي مستوى الـ energy بتاع الـ products."}},"explanation":"الجزيئات بتتفاعل لما تتصادم وهي معاها energy كفاية تكسر الـ bonds بتاعتها، غير كده مفيش reaction. الـ activation energy هي أقل energy لازم الجزيء يكسبها عشان يتفاعل وقت التصادم. وعلى الـ energy profile هي الطلعة من الـ reactants لفوق لحد قمة الحدبة. هي مش الـ energy اللي بتطلع (النزلة من الـ reactants للـ products)، والـ catalyst مش بيزوّد energy."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":15,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":62,"page_to":62,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-kin.activation-energy-2","kind":"question","version":1,"ord":311,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"kin.activation-energy","concepts":[{"concept_id":"kin.activation-energy","role":"primary"}],"title":"chem-s3-en.question-kin.activation-energy-2","payload":{"stem":"The graph shows the energy profile of a reaction (made-up values). What is the activation energy of this reaction?","tags":["diagnostic","prerequisite","read-the-graph","new-case"],"type":"mcq","bloom":"apply","figure":{"root":"c","elements":{"c":{"type":"Chart","props":{"kind":"line","unit":"kJ","title":"Energy profile (made-up values)","series":[{"name":"Reaction","points":[{"x":0,"y":50},{"x":1,"y":50},{"x":2,"y":110},{"x":3,"y":165},{"x":4,"y":180},{"x":5,"y":165},{"x":6,"y":130},{"x":7,"y":120},{"x":8,"y":120}]}],"caption":"Reactants at 50 kJ, top of the hump at 180 kJ, products at 120 kJ.","x_label":"Progress of reaction","y_label":"Potential energy","annotations":[{"x":0,"text":"reactants 50"},{"x":4,"text":"top of hump 180"},{"x":8,"text":"products 120"}]},"children":[]}}},"choices":[{"id":"a","text":"130 kJ","correct":true},{"id":"b","text":"180 kJ","correct":false},{"id":"c","text":"70 kJ","correct":false},{"id":"d","text":"60 kJ","correct":false}],"book_ref":"Ch.3 activation energy, pp.61-62; energy profile as in Ch.1 fig 1-3, p.15","difficulty":3,"concept_ids":["kin.activation-energy"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right. From the reactants (50) up to the top of the hump (180)."},"b":{"why":"180 is the height of the hump from zero, but the molecules start their climb at the reactants, 50 kJ.","feedback":"Misconception: Reads the activation energy as the height of the hump from zero."},"c":{"why":"70 kJ is the gap between reactants and products, not the climb over the hump.","feedback":"Misconception: Activation energy is the energy change between reactants and products."},"d":{"why":"You measured from the products to the top, but the reaction starts at the reactants.","feedback":"Misconception: Measures the hump from the products instead of the reactants."}},"explanation":"Activation energy is measured from the reactants up to the top of the hump. Here: 180 − 50 = 130 kJ. The products (120 kJ) are higher than the reactants (50 kJ), so this reaction takes in 70 kJ overall. That 70 kJ is the energy change, not the activation energy. The climb up and the change from reactants to products are two different things."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. من الـ reactants (50) لفوق لحد قمة الحدبة (180)."},"b":{"why":"الـ 180 ده ارتفاع الحدبة من الصفر، لكن الجزيئات بتبدأ طلعتها من مستوى الـ reactants (50 kJ).","feedback":"الفكرة الغلط: إنك تقرا الـ activation energy على إنها ارتفاع الحدبة من الصفر."},"c":{"why":"الـ 70 kJ دي الفرق بين الـ reactants والـ products، مش الطلوع فوق الحدبة.","feedback":"الفكرة الغلط: إن الـ activation energy هي التغيير في الـ energy بين الـ reactants والـ products."},"d":{"why":"إنت قست من الـ products لحد القمة، لكن الـ reaction بيبدأ من الـ reactants، مش من الـ products.","feedback":"الفكرة الغلط: إنك تقيس الحدبة من الـ products بدل الـ reactants."}},"explanation":"الـ activation energy بتتقاس من الـ reactants لفوق لحد قمة الحدبة. هنا: 180 − 50 = 130 kJ. الـ products (120 kJ) أعلى من الـ reactants (50 kJ)، يعني الـ reaction ده في المجمل بيمتص 70 kJ. والـ 70 kJ دي هي التغيير في الـ energy، مش الـ activation energy. الطلعة لفوق والتغيير من الـ reactants للـ products حاجتين مختلفين."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":16,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":62,"page_to":62,"section_key":"ch3","section_title":"Chemical Equilibrium","section_path":["Chemical Equilibrium"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.equation-reading-1","kind":"question","version":1,"ord":312,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"chem.equation-reading","concepts":[{"concept_id":"chem.equation-reading","role":"primary"}],"title":"chem-s3-en.question-chem.equation-reading-1","payload":{"stem":"Read the equation: $\\ce{4NH3(g) + 5O2(g) ->[Pt][850\\,^{\\circ}C] 4NO(g) + 6H2O(v)}$ (Pt is platinum). What is the platinum in this reaction?","tags":["diagnostic","prerequisite","warm-up","new-case"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"A catalyst: it is not used up, so it is written over the arrow.","correct":true},{"id":"b","text":"A reactant: it reacts with ammonia and oxygen.","correct":false},{"id":"c","text":"A product: it forms during the reaction.","correct":false},{"id":"d","text":"A sign that the reaction gives out heat.","correct":false}],"book_ref":"Prerequisite; equations with conditions over the arrow, e.g. Haber-Bosch, Ch.1 p.15","difficulty":2,"concept_ids":["chem.equation-reading"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right. What is written over the arrow is a condition, not a reactant or a product."},"b":{"why":"Reactants stand before the arrow, and Pt is written over the arrow, not before it.","feedback":"Misconception: A catalyst over the arrow is a reactant."},"c":{"why":"Products stand after the arrow, and Pt is not on the right side of the equation.","feedback":"Misconception: Anything near the arrow is formed by the reaction."},"d":{"why":"Δ or a temperature over the arrow is heat the reaction needs, not heat it gives out. Pt is the symbol of an element, and an element over the arrow is a catalyst.","feedback":"Misconception: A condition written over the arrow shows heat that the reaction gives out."}},"explanation":"Reactants come before the arrow, products after it. What is written over or under the arrow is a condition: a temperature, a pressure, heating (Δ) or a catalyst. Here 850 °C is the temperature and Pt is the catalyst. A catalyst is not used up, so it appears on neither side. The same rule applies to Fe in the Haber-Bosch equation."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. اللي مكتوب فوق السهم ده condition، مش reactant ولا product."},"b":{"why":"الـ reactants بتقف قبل السهم، والـ Pt مكتوب فوق السهم، مش قبله.","feedback":"الفكرة الغلط: إن الـ catalyst اللي فوق السهم يبقى reactant."},"c":{"why":"الـ products بتقف بعد السهم، والـ Pt مش موجود على يمين الـ equation.","feedback":"الفكرة الغلط: إن أي حاجة جنب السهم بتتكوّن من الـ reaction."},"d":{"why":"الـ Δ أو الـ temperature اللي فوق السهم دي حرارة الـ reaction محتاجاها، مش حرارة بتطلّعها. والـ Pt ده symbol لـ element، والـ element المكتوب فوق السهم بيبقى condition للـ reaction، مش علامة على حرارة.","feedback":"الفكرة الغلط: إن الـ condition المكتوب فوق السهم معناه حرارة الـ reaction بتطلّعها."}},"explanation":"الـ reactants بتيجي قبل السهم، والـ products بعده. واللي مكتوب فوق السهم أو تحته ده condition: temperature، أو pressure، أو تسخين (Δ)، أو catalyst. هنا 850 °C هي الـ temperature، والـ Pt هو الـ catalyst. والـ catalyst مش بيتستهلك، عشان كده مش بيظهر لا في ناحية الـ reactants ولا في ناحية الـ products. ونفس القاعدة دي بتنطبق على الـ Fe في الـ Haber-Bosch equation."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":17,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.equation-reading-2","kind":"question","version":1,"ord":313,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"chem.equation-reading","concepts":[{"concept_id":"chem.equation-reading","role":"primary"}],"title":"chem-s3-en.question-chem.equation-reading-2","payload":{"stem":"Which statement reads this equation correctly? $\\ce{2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g)}$","tags":["diagnostic","prerequisite","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Solid sodium and liquid water give sodium hydroxide dissolved in water, and hydrogen gas.","correct":true},{"id":"b","text":"Solid sodium and liquid water give solid sodium hydroxide that does not dissolve, and hydrogen gas.","correct":false},{"id":"c","text":"Solid sodium and water vapour give sodium hydroxide dissolved in water, and hydrogen gas.","correct":false},{"id":"d","text":"Solid sodium and liquid water give sodium hydroxide dissolved in water, and hydrogen dissolved in water.","correct":false}],"book_ref":"Prerequisite; state symbols (s), (l), (g), (aq), (v) used in Ch.1 equations, pp.15, 21-24","difficulty":2,"concept_ids":["chem.equation-reading"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Right. (aq) means dissolved in water, and (g) means gas."},"b":{"why":"The symbol after NaOH is (aq), not (s). (aq) means the substance is dissolved in water.","feedback":"Misconception: (aq) means insoluble or solid."},"c":{"why":"Water vapour would be written (v), but the letter after $\\ce{H2O}$ here is (l): liquid water.","feedback":"Misconception: Mixes up (l) and (v)."},"d":{"why":"The letter after $\\ce{H2}$ is (g), not (aq): hydrogen is a gas here.","feedback":"Misconception: Every product in a reaction with water is aqueous."}},"explanation":"State symbols: (s) solid, (l) liquid, (g) gas, (v) vapour, (aq) aqueous, which means dissolved in water. So Na(s) is solid sodium, H2O(l) is liquid water, NaOH(aq) is sodium hydroxide dissolved in water, and H2(g) is hydrogen gas. Always read the letter after each formula; do not guess the state."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ (aq) معناها dissolved في المية، والـ (g) معناها gas."},"b":{"why":"الـ symbol اللي بعد الـ NaOH هو (aq)، مش (s). والـ (aq) معناها إن المادة دايبة في المية.","feedback":"الفكرة الغلط: إن الـ (aq) معناها insoluble أو solid."},"c":{"why":"لو كان ده water vapour كان هيتكتب (v)، لكن الحرف اللي بعد الـ $\\ce{H2O}$ هنا هو (l).","feedback":"الفكرة الغلط: إنك تلخبط بين الـ (l) والـ (v)."},"d":{"why":"الحرف اللي بعد الـ $\\ce{H2}$ مش (aq)؛ ده (g).","feedback":"الفكرة الغلط: إن كل product في reaction مع المية بيبقى aqueous."}},"explanation":"الـ state symbols: الـ (s) يعني solid، والـ (l) liquid، والـ (g) gas، والـ (v) vapour، والـ (aq) aqueous، يعني dissolved في المية. يبقى الـ Na(s) هو solid sodium، والـ H2O(l) هو liquid water، والـ NaOH(aq) هو sodium hydroxide dissolved في المية، والـ H2(g) هو hydrogen gas. دايمًا اقرا الحرف اللي بعد كل formula، وماتخمّنش الـ state."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":18,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.ammonia-haber-1","kind":"question","version":1,"ord":314,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"chem.ammonia-haber","concepts":[{"concept_id":"chem.ammonia-haber","role":"primary"}],"title":"chem-s3-en.question-chem.ammonia-haber-1","payload":{"stem":"Which set gives the catalyst and conditions of the Haber-Bosch method for preparing ammonia, as in the book?","tags":["diagnostic","prerequisite","warm-up"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"Iron (Fe), 500 °C, 200 atm","correct":true},{"id":"b","text":"Vanadium pentoxide ($\\ce{V2O5}$), 450 °C","correct":false},{"id":"c","text":"Finely divided nickel (Ni), 500 °C, 200 atm","correct":false},{"id":"d","text":"Iron (Fe), 200 °C, 500 atm","correct":false}],"book_ref":"Ch.1 point 5 Catalytic activity, Haber-Bosch equation, p.15","difficulty":2,"concept_ids":["chem.ammonia-haber"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Right. All three are written over the arrow in the book's equation."},"b":{"why":"$\\ce{V2O5}$ is the catalyst of another industry: the contact method for sulphuric acid.","feedback":"Misconception: Swaps the Haber-Bosch and contact-method catalysts."},"c":{"why":"Finely divided nickel helps add hydrogen to oils. The book names a different metal for ammonia.","feedback":"Misconception: Any hydrogen reaction uses a nickel catalyst."},"d":{"why":"The catalyst is right, but the two numbers are swapped: the temperature is 500 °C and the pressure is 200 atm.","feedback":"Misconception: Swaps the temperature and pressure values."}},"explanation":"The book writes: $\\ce{N2(g) + 3H2(g) ->[500\\,^{\\circ}C / 200\\,atm,\\ Fe] 2NH3(g)}$. Iron is the catalyst, at 500 °C and 200 atm (200 times normal air pressure). $\\ce{V2O5}$ at 450 °C belongs to the contact method for sulphuric acid. Finely divided nickel is used in the hydrogenation of oils."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. التلاتة دول مكتوبين فوق السهم في الـ equation بتاعة الكتاب."},"b":{"why":"الـ $\\ce{V2O5}$ ده catalyst في صناعة تانية: الـ contact method لتحضير الـ sulphuric acid.","feedback":"الفكرة الغلط: إنك تبدّل الـ catalyst بتاع الـ Haber-Bosch بالـ catalyst بتاع الـ contact method."},"c":{"why":"الـ finely divided nickel بيساعد في إضافة الـ hydrogen للزيوت، والكتاب مش بيذكره كـ catalyst للـ ammonia.","feedback":"الفكرة الغلط: إن أي reaction فيه hydrogen بيستخدم nickel كـ catalyst."},"d":{"why":"الـ catalyst صح، لكن الرقمين متبدّلين: الـ temperature هي 500 °C والضغط 200 atm.","feedback":"الفكرة الغلط: إنك تبدّل قيمة الـ temperature بقيمة الـ pressure."}},"explanation":"الكتاب كاتب: $\\ce{N2(g) + 3H2(g) ->[500\\,^{\\circ}C / 200\\,atm,\\ Fe] 2NH3(g)}$. الـ iron هو الـ catalyst، عند 500 °C و 200 atm (يعني 200 ضعف ضغط الهوا العادي). أما الـ $\\ce{V2O5}$ عند 450 °C فده بتاع الـ contact method لتحضير الـ sulphuric acid. والـ finely divided nickel بيتستخدم في الـ hydrogenation of oils."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":19,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.ammonia-haber-2","kind":"question","version":1,"ord":315,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"chem.ammonia-haber","concepts":[{"concept_id":"chem.ammonia-haber","role":"primary"}],"title":"chem-s3-en.question-chem.ammonia-haber-2","payload":{"stem":"In the Haber-Bosch method, $\\ce{N2 + 3H2 -> 2NH3}$, 12 molecules of ammonia are produced. How many molecules of hydrogen reacted?","tags":["diagnostic","prerequisite","calculation","new-case"],"type":"numeric","bloom":"apply","answer":{"unit":"molecules","value":18,"tolerance":0},"book_ref":"Ch.1 point 5 Catalytic activity, Haber-Bosch equation, p.15","difficulty":3,"concept_ids":["chem.ammonia-haber"],"est_seconds":60},"layer":{"explanation":"The equation says 3 H2 give 2 NH3. 12 NH3 is 6 sets of 2 NH3. Each set needs 3 H2, so 6 × 3 = 18 molecules of H2. Check with atoms: 12 NH3 contain 36 H atoms; 18 H2 also contain 36 H atoms. Most likely wrong answer: 12 (reading H2 and NH3 as one to one). Another: 6 (dividing by 2 instead of using the ratio 3 : 2). Another: 8 (using the ratio upside down: 12 × 2 ÷ 3)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ equation بتقول إن 3 H2 بيدّوا 2 NH3. والـ 12 NH3 دول عبارة عن 6 مجموعات، كل مجموعة فيها 2 NH3. وكل مجموعة محتاجة 3 H2، يبقى 6 × 3 = 18 molecules من الـ H2. اتأكد بالذرات: الـ 12 NH3 فيهم 36 ذرة H، والـ 18 H2 برضه فيهم 36 ذرة H. أشهر إجابة غلط: 12 (إنك تقرا الـ H2 والـ NH3 كأنهم واحد لواحد). وإجابة غلط تانية: 6 (إنك تقسم على 2 بدل ما تستخدم النسبة 3 : 2). وكمان: 8 (إنك تقلب النسبة: 12 × 2 ÷ 3)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":20,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-properties-1","kind":"question","version":1,"ord":316,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.magnetic-properties","concepts":[{"concept_id":"te.magnetic-properties","role":"primary"}],"title":"chem-s3-en.question-te.magnetic-properties-1","payload":{"stem":"Classify the following ions into paramagnetic and diamagnetic. The 3d configuration of each ion is given.","tags":["classify","exam-style","new-case"],"type":"classify","bloom":"apply","answer":{"dia":["i4","i5"],"para":["i1","i2","i3"]},"choices":[{"id":"i1","text":"$\\ce{V^3+}$ ($3d^2$)"},{"id":"i2","text":"$\\ce{Mn^3+}$ ($3d^4$)"},{"id":"i3","text":"$\\ce{Co^3+}$ ($3d^6$)"},{"id":"i4","text":"$\\ce{Ti^4+}$ ($3d^0$)"},{"id":"i5","text":"$\\ce{Ga^3+}$ ($3d^{10}$, gallium)"}],"book_ref":"Ch.1 general properties, point 4 (a, b) and exercise, pp.13-14","categories":[{"id":"para","label":"Paramagnetic"},{"id":"dia","label":"Diamagnetic"}],"difficulty":3,"concept_ids":["te.magnetic-properties"],"est_seconds":90},"layer":{"choices":{"i1":{"why":"By Hund's rule, the two electrons take one box each instead of sharing one, so both are unpaired."},"i2":{"why":"By Hund's rule, the four electrons go one per box, so no electron has a partner: there are 4 unpaired electrons."},"i3":{"why":"Six is an even number, but even does not mean all paired: five electrons go one per box first, then one pairs up, leaving 4 unpaired."},"i4":{"why":"Titanium is a transition element, but this ion has no 3d electrons, so it has no unpaired electrons."},"i5":{"why":"Ten electrons fill the five boxes completely, so the electrons are all paired and there is no unpaired electron."}},"explanation":"Fill the five 3d boxes by Hund's rule: one electron in each box first, then pairing. 3d² has 2 unpaired, 3d⁴ has 4, and 3d⁶ has 4 (one pair and four unpaired electrons). Any unpaired electron makes the ion paramagnetic: it is attracted to the external magnetic field. 3d⁰ has no electrons in 3d, and 3d¹⁰ has all electrons paired. So their magnetic moment is zero, and they are diamagnetic: they repel the external field. Note: the number of d electrons does not decide by itself. Only unpaired electrons count."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"i1":{"why":"اتنين electrons في خمس مربعات. حسب الـ Hund's rule، كل electron بياخد مربع لوحده، فالاتنين بيبقوا unpaired."},"i2":{"why":"أربعة electrons في خمس مربعات، واحد في كل مربع الأول، فمفيش أي electron ليه شريك: الأربعة unpaired."},"i3":{"why":"ستة رقم زوجي، لكن زوجي مش معناه إن كله paired. لما المربعات تتملي واحد واحد بيتكوّن زوج واحد وبيفضل أربعة unpaired electrons."},"i4":{"why":"الـ titanium هو transition element، لكن الـ ion ده مفيهوش 3d electrons، فمفيهوش unpaired electrons."},"i5":{"why":"عشرة electrons بيملوا الخمس مربعات، فكل الـ electrons paired ومفيش مربع فيه unpaired electron."}},"explanation":"املا الخمس مربعات بتوع الـ 3d حسب الـ Hund's rule: electron واحد في كل مربع الأول، وبعدين الأزواج. الـ 3d² فيه 2 unpaired، والـ 3d⁴ فيه 4، والـ 3d⁶ فيه 4 (زوج واحد وأربعة unpaired electrons). أي unpaired electron بيخلّي الـ ion يبقى paramagnetic: يعني بيتجذب للـ external magnetic field. أما الـ 3d⁰ فمفيهوش electrons في الـ 3d، والـ 3d¹⁰ كل الـ electrons فيه paired. فالـ magnetic moment بتاعهم بصفر، ويبقوا diamagnetic: بيتنافروا مع الـ external field. خلّي بالك: عدد الـ d electrons لوحده مش هو اللي بيحدد. الـ unpaired electrons تحديدًا هما اللي بيفرقوا."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":21,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-moment-from-config-1","kind":"question","version":1,"ord":317,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.magnetic-moment-from-config","concepts":[{"concept_id":"te.magnetic-moment-from-config","role":"primary"}],"title":"chem-s3-en.question-te.magnetic-moment-from-config-1","payload":{"stem":"How many unpaired electrons are there in the metal ion of chromium(II) chloride, $\\ce{CrCl2}$? ($_{24}$Cr)","tags":["exam-style","calculation","new-case"],"type":"numeric","bloom":"apply","answer":{"unit":"unpaired electrons","value":4,"tolerance":0},"book_ref":"Ch.1 magnetic properties, worked exercises, p.14; Cr configuration, p.8","difficulty":4,"concept_ids":["te.magnetic-moment-from-config"],"est_seconds":90},"layer":{"explanation":"Step 1: oxidation state. Cl is −1, and two Cl give −2, so chromium is +2. Step 2: the ion's configuration. Chromium is [Ar] 4s¹ 3d⁵ (abnormal, half-filled 3d). Cr²⁺ loses the 4s¹ electron first, then one 3d electron: [Ar] 3d⁴. Step 3: boxes by Hund's rule. The four 3d electrons go one in each of four boxes, and the fifth box stays empty. So there are 4 unpaired electrons, and CrCl2 is paramagnetic. Common wrong answers, each from one mistake: 6 ← counting the atom instead of the ion: [Ar] 4s¹ 3d⁵ has 1 unpaired in 4s and 5 in 3d, so 6. 5 ← removing only one electron (the 4s¹): that gives Cr⁺, [Ar] 3d⁵, so 5. 3 ← mixing up Cr²⁺ with Cr³⁺: [Ar] 3d³, so 3. 2 ← writing Cr as [Ar] 4s² 3d⁴ and removing both electrons from 3d: [Ar] 4s² 3d², where 4s² is paired and the two 3d electrons are in separate boxes, so 2. 0 ← pairing the four 3d electrons in two boxes, which breaks Hund's rule: 0."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"خطوة 1: الـ oxidation state. الـ Cl بـ −1، واتنين Cl يدّوا −2، يعني الـ chromium بـ +2. خطوة 2: الـ configuration بتاع الـ ion. الـ chromium هو [Ar] 4s¹ 3d⁵ (abnormal، والـ 3d نصه مليان). الـ Cr²⁺ بيفقد الـ 4s¹ electron الأول، وبعدين electron واحد من الـ 3d: يبقى [Ar] 3d⁴. خطوة 3: المربعات حسب الـ Hund's rule. الأربعة 3d electrons بيتوزعوا واحد في كل مربع من أربع مربعات، والمربع الخامس بيفضل فاضي. يعني فيه 4 unpaired electrons، والـ CrCl2 كده paramagnetic. إجابات غلط بتتكرر، وكل واحدة جاية من غلطة واحدة: 6 ← عدّيت الذرة بدل الـ ion: الـ [Ar] 4s¹ 3d⁵ فيه 1 unpaired في الـ 4s و5 في الـ 3d، فيطلعوا 6. 5 ← شلت electron واحد بس (الـ 4s¹): ده يدّي Cr⁺، [Ar] 3d⁵، فيطلعوا 5. 3 ← لخبطت الـ Cr²⁺ مع الـ Cr³⁺: [Ar] 3d³، فيطلعوا 3. 2 ← كتبت الـ Cr على إنه [Ar] 4s² 3d⁴ وشلت الاتنين electrons من الـ 3d: [Ar] 4s² 3d²، والـ 4s² فيه زوج والاتنين 3d electrons في مربعين منفصلين، فيطلعوا 2. 0 ← عملت الأربعة 3d electrons أزواج في مربعين، وده ضد الـ Hund's rule: فيطلعوا 0."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":22,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.catalytic-activity-1","kind":"question","version":1,"ord":318,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.catalytic-activity","concepts":[{"concept_id":"te.catalytic-activity","role":"primary"}],"title":"chem-s3-en.question-te.catalytic-activity-1","payload":{"stem":"Give reasons: Most of the first transition elements have catalytic activity.","tags":["exam-style","give-reasons","book-evaluation"],"type":"short","bloom":"understand","answer":"Key points: (1) Their 4s and 3d electrons are used to form bonds between the atoms of the catalyst surface and the reacting molecules. (2) This increases the concentration of the reacting molecules on the surface of the catalyst. (3) It weakens the bonds in the reactant molecules. (4) So the activation energy decreases and the speed of the reaction increases.","book_ref":"Ch.1 general properties, point 5 Catalytic activity, p.15; Evaluation Q7.11, p.27","difficulty":3,"concept_ids":["te.catalytic-activity"],"est_seconds":90},"layer":{"explanation":"The book links catalytic activity to the 4s and 3d electrons. These electrons form bonds between the surface atoms of the metal and the reacting molecules. More reactant molecules then gather on the surface, so their concentration there increases. The bonds inside the reactant molecules are weakened. So the activation energy decreases, and the reaction speeds up. Key words: 4s and 3d electrons, bonds with the surface, concentration on the surface, weaken the bonds, decrease the activation energy. Most likely wrong answer: 'they give the molecules energy'. A catalyst does not supply energy; it lowers the barrier. Another: 'they react and are used up'. A catalyst is not used up."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الكتاب بيربط الـ catalytic activity بالـ 4s والـ 3d electrons. الـ electrons دي بتكوّن bonds بين ذرات سطح الـ metal والـ reacting molecules. فبتتجمع reactant molecules أكتر على السطح، يعني الـ concentration بتاعها هناك بيزيد. والـ bonds اللي جوه الـ reactant molecules بتضعف. فالـ activation energy بتقل، والـ reaction بيسرع. الكلمات المهمة: 4s and 3d electrons، bonds with the surface، concentration on the surface، weaken the bonds، decrease the activation energy. أكتر إجابة غلط متوقعة: 'they give the molecules energy'. الـ catalyst مش بيدّي energy؛ هو بيوطّي الحاجز. وإجابة غلط تانية: 'they react and are used up'. الـ catalyst مش بيتستهلك."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":23,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"11","relation":"from_book"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.catalysis-examples-1","kind":"question","version":1,"ord":319,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.catalysis-examples","concepts":[{"concept_id":"te.catalysis-examples","role":"primary"}],"title":"chem-s3-en.question-te.catalysis-examples-1","payload":{"stem":"Match each process in column (A) with its catalyst and conditions in column (B), as in the book.","tags":["exam-style","match"],"type":"match","bloom":"remember","answer":[["l1","r1"],["l2","r2"],["l3","r3"],["l4","r4"]],"choices":[{"id":"l1","text":"Hydrogenation of oils"},{"id":"l2","text":"Preparation of ammonia (Haber-Bosch method)"},{"id":"l3","text":"Preparation of sulphuric acid (contact method), first step"},{"id":"l4","text":"Decomposition of hydrogen peroxide (fig 1-3)"},{"id":"r1","text":"Finely divided nickel"},{"id":"r2","text":"Iron, 500 °C, 200 atm"},{"id":"r3","text":"$\\ce{V2O5}$, 450 °C"},{"id":"r4","text":"$\\ce{MnO2}$"}],"book_ref":"Ch.1 point 5 Catalytic activity, pp.14-15 (fig 1-3)","difficulty":2,"concept_ids":["te.catalysis-examples"],"est_seconds":60},"layer":{"choices":{"l1":{"why":"In the book, finely divided nickel is the catalyst of the hydrogenation of oils."},"l2":{"why":"Ammonia is prepared by the Haber-Bosch method over iron at 500 °C and 200 atm."},"l3":{"why":"In the contact method, $\\ce{V2O5}$ at 450 °C catalyses the oxidation of $\\ce{SO2}$ to $\\ce{SO3}$, the first step to sulphuric acid."},"l4":{"why":"Fig 1-3 shows $\\ce{MnO2}$ as the catalyst that decomposes $\\ce{H2O2}$ into water and oxygen."},"r1":{"why":"Finely divided nickel is the book's catalyst for the hydrogenation of oils."},"r2":{"why":"Iron with 500 °C and 200 atm are the conditions of the Haber-Bosch method for ammonia."},"r3":{"why":"$\\ce{V2O5}$ at 450 °C belongs to the contact method: it catalyses $\\ce{2SO2 + O2 -> 2SO3}$."},"r4":{"why":"$\\ce{MnO2}$ is the catalyst in fig 1-3, the decomposition of hydrogen peroxide."}},"explanation":"Each process has its own catalyst. Finely divided nickel: hydrogenation of oils (adding hydrogen turns liquid oils into solid fats). Iron at 500 °C and 200 atm: ammonia by the Haber-Bosch method. Vanadium pentoxide, $\\ce{V2O5}$, at 450 °C: oxidation of $\\ce{SO2}$ to $\\ce{SO3}$ in the contact method for sulphuric acid. $\\ce{MnO2}$: decomposition of $\\ce{H2O2}$ into water and oxygen. The most common slip is swapping Fe and $\\ce{V2O5}$ between ammonia and sulphuric acid."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"l1":{"why":"في الكتاب، الـ finely divided nickel هو الـ catalyst بتاع الـ hydrogenation of oils."},"l2":{"why":"الـ ammonia بتتحضّر بالـ Haber-Bosch method على الـ iron عند 500 °C و200 atm."},"l3":{"why":"في الـ contact method، الـ $\\ce{V2O5}$ عند 450 °C بيساعد في أكسدة الـ $\\ce{SO2}$ لـ $\\ce{SO3}$، أول خطوة للـ sulphuric acid."},"l4":{"why":"شكل 1-3 بيوضّح الـ $\\ce{MnO2}$ كـ catalyst بيفكّك الـ $\\ce{H2O2}$ لمية و oxygen."},"r1":{"why":"الـ finely divided nickel هو الـ catalyst اللي في الكتاب للـ hydrogenation of oils."},"r2":{"why":"الـ iron مع 500 °C و200 atm هي ظروف الـ Haber-Bosch method بتاعة الـ ammonia."},"r3":{"why":"الـ $\\ce{V2O5}$ عند 450 °C بتاع الـ contact method: بيساعد في $\\ce{2SO2 + O2 -> 2SO3}$."},"r4":{"why":"الـ $\\ce{MnO2}$ هو الـ catalyst اللي في شكل 1-3، تفكيك الـ hydrogen peroxide."}},"explanation":"كل عملية ليها الـ catalyst بتاعها. الـ finely divided nickel: للـ hydrogenation of oils (إضافة الـ hydrogen بتحوّل الزيوت السايلة لدهون صلبة). الـ iron عند 500 °C و200 atm: للـ ammonia بالـ Haber-Bosch method. الـ vanadium pentoxide، $\\ce{V2O5}$، عند 450 °C: لأكسدة الـ $\\ce{SO2}$ لـ $\\ce{SO3}$ في الـ contact method بتاعة الـ sulphuric acid. الـ $\\ce{MnO2}$: لتفكيك الـ $\\ce{H2O2}$ لمية و oxygen. أشهر غلطة: إنك تبدّل الـ Fe والـ $\\ce{V2O5}$ بين الـ ammonia والـ sulphuric acid."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":24,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-properties-2","kind":"question","version":1,"ord":320,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.magnetic-properties","concepts":[{"concept_id":"te.magnetic-properties","role":"primary"},{"concept_id":"te.magnetic-moment-from-config","role":"secondary"}],"title":"chem-s3-en.question-te.magnetic-properties-2","payload":{"stem":"Give reasons: Nickel(II) chloride, $\\ce{NiCl2}$, is attracted to an external magnetic field, while zinc oxide, $\\ce{ZnO}$, is repelled by it. ($_{28}$Ni, $_{30}$Zn)","tags":["exam-style","give-reasons","new-case"],"type":"short","bloom":"apply","answer":"Key points: (1) In NiCl2, nickel is Ni²⁺: [Ar] 3d⁸, with 2 unpaired electrons. (2) Spinning unpaired electrons form a magnetic field, so NiCl2 is paramagnetic: attracted to the external magnetic field. (3) In ZnO, zinc is Zn²⁺: [Ar] 3d¹⁰, all electrons paired. (4) Paired electrons have opposite spins, so the magnetic moment is zero; ZnO is diamagnetic: it repels the external magnetic field.","book_ref":"Ch.1 general properties, point 4 (a, b), pp.13-14; form of Evaluation Q7.6, p.27","difficulty":4,"concept_ids":["te.magnetic-properties","te.magnetic-moment-from-config"],"est_seconds":120},"layer":{"explanation":"Step 1: find the ions. Cl is −1, so nickel is +2. O is −2, so zinc is +2. Step 2: write the 3d configurations, losing 4s first. Ni²⁺ is [Ar] 3d⁸; Zn²⁺ is [Ar] 3d¹⁰. Step 3: fill boxes by Hund's rule. 3d⁸ = three pairs and two unpaired electrons: 2 unpaired. 3d¹⁰ = five pairs: 0 unpaired. Step 4: an unpaired electron spins and forms a magnetic field, so the substance is attracted (paramagnetic). When all electrons are paired, opposite spins cancel, the magnetic moment is zero, and the substance is repelled (diamagnetic). Most likely wrong answer: 'zinc is not a metal that magnets attract'. Diamagnetic does not mean 'not affected'; ZnO is repelled. Another wrong answer: counting the atoms (Ni [Ar] 4s² 3d⁸) instead of the ions."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"خطوة 1: حدد الـ ions. الـ Cl بـ −1، يبقى الـ nickel بـ +2. والـ O بـ −2، يبقى الـ zinc بـ +2. خطوة 2: اكتب الـ 3d configurations، والـ 4s هو اللي بيفقد الـ electrons الأول. الـ Ni²⁺ هو [Ar] 3d⁸، والـ Zn²⁺ هو [Ar] 3d¹⁰. خطوة 3: املا المربعات حسب الـ Hund's rule. الـ 3d⁸ = تلات أزواج و2 unpaired electrons. والـ 3d¹⁰ = خمس أزواج: 0 unpaired. خطوة 4: الـ unpaired electron وهو بيلف بيعمل magnetic field، فالمادة بتتجذب (paramagnetic). ولما كل الـ electrons تبقى paired، الـ opposite spins بتلغي بعض، والـ magnetic moment بيبقى صفر، والمادة بتتنافر (diamagnetic). أشهر إجابة غلط: «الـ zinc مش metal من اللي الـ magnets بتشدها». الـ diamagnetic مش معناها «مش بتتأثر»؛ الـ ZnO بيتنافر فعلًا. وغلطة تانية: إنك تحسب على الذرات (Ni [Ar] 4s² 3d⁸) بدل الـ ions."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":25,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-moment-from-config-2","kind":"question","version":1,"ord":321,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.magnetic-moment-from-config","concepts":[{"concept_id":"te.magnetic-moment-from-config","role":"primary"}],"title":"chem-s3-en.question-te.magnetic-moment-from-config-2","payload":{"stem":"Arrange the following compounds in ascending order according to their magnetic moment (smallest first). ($_{21}$Sc, $_{26}$Fe, $_{27}$Co, $_{28}$Ni)","tags":["exam-style","arrange","new-case"],"type":"order","bloom":"analyze","answer":["y","z","x","w"],"choices":[{"id":"w","text":"$\\ce{Fe(NO3)3}$"},{"id":"x","text":"$\\ce{CoO}$"},{"id":"y","text":"$\\ce{ScCl3}$"},{"id":"z","text":"$\\ce{Ni(OH)2}$"}],"book_ref":"Ch.1 magnetic properties, exercise 'Re arrange ... according to their magnetic moment', p.14","difficulty":4,"concept_ids":["te.magnetic-moment-from-config"],"est_seconds":150},"layer":{"choices":{"w":{"why":"Nitrate is −1, so iron is +3 here; removing the 4s electrons first leaves 3d⁵, with 5 unpaired electrons."},"x":{"why":"Cobalt is +2 here: its seven 3d electrons go one per box first, then two of them pair up, leaving 3 unpaired."},"y":{"why":"Scandium is a transition element, but its ion in this compound keeps no 3d electrons, so none is unpaired."},"z":{"why":"Hydroxide is −1, so nickel is +2: the ion's eight 3d electrons give 2 unpaired, not 8."}},"explanation":"The magnetic moment increases with the number of unpaired electrons, so count them for each metal ion. ScCl3: Sc³⁺ is [Ar] 3d⁰, 0 unpaired (diamagnetic). Ni(OH)2: Ni²⁺ is [Ar] 3d⁸, 2 unpaired. CoO: Co²⁺ is [Ar] 3d⁷, 3 unpaired. Fe(NO3)3: Fe³⁺ is [Ar] 3d⁵, 5 unpaired. Order: ScCl3 < Ni(OH)2 < CoO < Fe(NO3)3. Common slip 1: ordering by the total number of 3d electrons, which puts Ni²⁺ last. Common slip 2: counting the atoms instead of the ions."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"w":{"why":"الـ nitrate بـ −1، فالـ iron هنا بـ +3؛ لما الـ 4s electrons تمشي الأول بيفضل 3d⁵، وفيه 5 unpaired electrons."},"x":{"why":"سبعة 3d electrons في خمس مربعات: كل مربع بياخد واحد الأول، وبعدين اتنين بيعملوا أزواج، فبيفضل 3 unpaired."},"y":{"why":"الـ scandium هو transition element، لكن الـ ion بتاعه في الـ compound ده مابيفضلش معاه أي 3d electrons، فمفيش ولا واحد unpaired."},"z":{"why":"الـ hydroxide بـ −1، يعني الـ nickel بـ +2: التمن 3d electrons بتوع الـ ion بيدّوا 2 unpaired، مش 8."}},"explanation":"الـ magnetic moment بيزيد كل ما عدد الـ unpaired electrons يزيد، فعدّهم لكل metal ion. الـ ScCl3: الـ Sc³⁺ هو [Ar] 3d⁰، يعني 0 unpaired (diamagnetic). الـ Ni(OH)2: الـ Ni²⁺ هو [Ar] 3d⁸، يعني 2 unpaired. الـ CoO: الـ Co²⁺ هو [Ar] 3d⁷، يعني 3 unpaired. الـ Fe(NO3)3: الـ Fe³⁺ هو [Ar] 3d⁵، يعني 5 unpaired. الترتيب: ScCl3 < Ni(OH)2 < CoO < Fe(NO3)3. غلطة بتتكرر 1: إنك ترتّب على حسب العدد الكلي للـ 3d electrons، وده بيحط الـ Ni²⁺ في الآخر. غلطة بتتكرر 2: إنك تعدّ الذرات بدل الـ ions."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":26,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic.ex-b","section_title":"Order of magnetic moments","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties","Order of magnetic moments"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.catalytic-activity-2","kind":"question","version":2,"catalog_version":1,"ord":322,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.catalytic-activity","concepts":[{"concept_id":"te.catalytic-activity","role":"primary"},{"concept_id":"kin.activation-energy","role":"secondary"}],"title":"chem-s3-en.question-te.catalytic-activity-2","payload":{"stem":"The graph shows the energy profile of the same reaction without and with a catalyst (made-up values). Which statement is correct?","tags":["exam-style","read-the-graph","new-case"],"type":"mcq","bloom":"analyze","figure":{"root":"c","elements":{"c":{"type":"Chart","props":{"kind":"line","unit":"kJ","title":"Energy profile of one reaction (made-up values)","series":[{"name":"Without catalyst","points":[{"x":0,"y":100},{"x":1,"y":100},{"x":2,"y":170},{"x":3,"y":230},{"x":4,"y":250},{"x":5,"y":220},{"x":6,"y":110},{"x":7,"y":40},{"x":8,"y":40}]},{"name":"With catalyst","points":[{"x":0,"y":100},{"x":1,"y":100},{"x":2,"y":135},{"x":3,"y":162},{"x":4,"y":170},{"x":5,"y":155},{"x":6,"y":90},{"x":7,"y":40},{"x":8,"y":40}]}],"caption":"Reactants at 100 kJ, products at 40 kJ. Top of the hump: 250 kJ without catalyst, 170 kJ with catalyst.","x_label":"Progress of reaction","y_label":"Potential energy"},"children":[]}}},"choices":[{"id":"a","text":"The catalyst lowers the activation energy from 150 kJ to 70 kJ; the net energy released stays 60 kJ.","correct":true},{"id":"b","text":"The catalyst lowers the activation energy from 250 kJ to 170 kJ; the net energy released stays 60 kJ.","correct":false},{"id":"c","text":"The catalyst lowers the activation energy from 150 kJ to 70 kJ, so the net energy released rises by 80 kJ.","correct":false,"misconception_id":"te.catalytic-activity.mc2"},{"id":"d","text":"With the catalyst, the activation energy equals the net energy released, 60 kJ.","correct":false,"misconception_id":"kin.activation-energy.mc1"}],"book_ref":"Ch.1 point 5 Catalytic activity, energy profile fig 1-3, p.15","difficulty":4,"concept_ids":["te.catalytic-activity","kin.activation-energy"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Right. Only the hump changes; the reactant and product levels stay the same."},"b":{"why":"250 and 170 are the heights of the humps from zero, but the climb starts at the reactants (100 kJ).","feedback":"Misconception: Reads the activation energy as the height of the hump from zero."},"c":{"why":"Both curves start at 100 kJ and end at 40 kJ, so the energy released is 60 kJ on both. The catalyst changes the hump, not these levels.","feedback":"Misconception: A catalyst increases the energy released by the reaction."},"d":{"why":"60 kJ is the drop from reactants to products, not the climb up the hump.","feedback":"Misconception: Activation energy is the energy released by the reaction."}},"explanation":"Activation energy is measured from the reactants (100 kJ) up to the top of the hump. Without catalyst: 250 − 100 = 150 kJ. With catalyst: 170 − 100 = 70 kJ. The net energy released is the drop from reactants to products: 100 − 40 = 60 kJ, the same on both curves. So the catalyst lowers the activation energy only. It does not change the energy of the reactants or products, so the net energy released stays the same, as in the book's fig 1-3 for $\\ce{MnO2}$ and $\\ce{H2O2}$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. اللي بيتغير هو الحدبة لوحدها؛ مستوى الـ reactants والـ products بيفضل زي ما هو."},"b":{"why":"الـ 250 والـ 170 دول ارتفاع الحدبتين من الصفر، لكن الطلعة بتبدأ من الـ reactants (100 kJ).","feedback":"الفكرة الغلط: إنك تقرا الـ activation energy على إنها ارتفاع الحدبة من الصفر."},"c":{"why":"المنحنيين بيبدأوا عند 100 kJ وبيخلصوا عند 40 kJ، فالـ energy اللي بتطلع 60 kJ في الاتنين. الـ catalyst بيغيّر الحدبة، مش المستويات دي.","feedback":"الفكرة الغلط: إن الـ catalyst بيزوّد الـ energy اللي الـ reaction بيطلّعها."},"d":{"why":"الـ 60 kJ دي النزلة من الـ reactants للـ products، مش الطلعة لفوق الحدبة.","feedback":"الفكرة الغلط: إن الـ activation energy هي الـ energy اللي الـ reaction بيطلّعها."}},"explanation":"الـ activation energy بتتقاس من الـ reactants (100 kJ) لفوق لحد قمة الحدبة. من غير catalyst: 250 − 100 = 150 kJ. ومع الـ catalyst: 170 − 100 = 70 kJ. والـ net energy released هي النزلة من الـ reactants للـ products: 100 − 40 = 60 kJ، ونفس الرقم في المنحنيين. يعني الـ catalyst بيقلل الـ activation energy تحديدًا. مابيغيّرش الـ energy بتاعة الـ reactants ولا الـ products، فالـ net energy released بتفضل زي ما هي، زي ما الكتاب بيوضّح في شكل 1-3 للـ $\\ce{MnO2}$ والـ $\\ce{H2O2}$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":27,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.catalysis-examples-2","kind":"question","version":1,"ord":323,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.catalysis-examples","concepts":[{"concept_id":"te.catalysis-examples","role":"primary"},{"concept_id":"chem.ammonia-haber","role":"secondary"}],"title":"chem-s3-en.question-te.catalysis-examples-2","payload":{"stem":"A student wrote this equation for the Haber-Bosch method: $\\ce{N2(g) + H2(g) + Fe(s) -> NH3(g)}$. Rewrite it correctly, balanced, with the catalyst and conditions in their right place.","tags":["exam-style","write-the-equation","correct-the-mistake","equation"],"type":"short","bloom":"apply","answer":"\\ce{N2(g) + 3H2(g) ->[500\\,^{\\circ}C / 200\\,atm,\\ Fe] 2NH3(g)}","book_ref":"Ch.1 point 5 Catalytic activity, Haber-Bosch equation, p.15","difficulty":3,"concept_ids":["te.catalysis-examples","chem.ammonia-haber"],"est_seconds":120},"layer":{"explanation":"The student made three mistakes. (1) Fe is the catalyst, not a reactant. A catalyst is not used up, so it goes over the arrow. (2) The equation is not balanced: N2 has 2 N atoms and 3 H2 have 6 H atoms, which give 2 NH3. (3) The conditions are missing: 500 °C and 200 atm, written over the arrow with Fe. Grader looks for: coefficients 1, 3, 2; Fe over the arrow, not on the left; 500 °C and 200 atm; state symbols (g). Most likely wrong answer: balancing correctly but leaving Fe as a reactant."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الطالب عمل تلات غلطات. (1) الـ Fe هو الـ catalyst، مش reactant. والـ catalyst مابيتستهلكش، فمكانه فوق السهم. (2) المعادلة مش balanced: الـ N2 فيه 2 N atoms، والـ 3 H2 فيهم 6 H atoms، ودول بيدوا 2 NH3. (3) الـ conditions ناقصة: 500 °C و200 atm، بيتكتبوا فوق السهم مع الـ Fe. المصحح بيدور على: الـ coefficients 1، 3، 2؛ الـ Fe فوق السهم مش على الشمال؛ 500 °C و200 atm؛ والـ state symbols (g). أشهر غلطة: إنك توزن المعادلة صح لكن تسيب الـ Fe كـ reactant."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":28,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-properties-3","kind":"question","version":1,"ord":324,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.magnetic-properties","concepts":[{"concept_id":"te.magnetic-properties","role":"primary"}],"title":"chem-s3-en.question-te.magnetic-properties-3","payload":{"stem":"Write the scientific term: The substance that is attracted to the external magnetic field due to the presence of unpaired electrons.","tags":["exam-style","scientific-term"],"type":"short","bloom":"remember","answer":"Paramagnetic substance.","book_ref":"Ch.1 general properties, point 4a, p.13","difficulty":2,"concept_ids":["te.magnetic-properties"],"est_seconds":30},"layer":{"explanation":"The book defines the paramagnetic substance as the substance that is attracted to the external magnetic field, due to the presence of unpaired electrons. Most likely wrong answer: 'diamagnetic substance'. That is the opposite: all electrons are paired, and it repels the field. Another wrong answer: 'magnetic moment'. That is the strength of the magnetism, not the substance."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الكتاب بيعرّف الـ paramagnetic substance إنها المادة اللي بتتجذب للـ external magnetic field، بسبب وجود unpaired electrons. أشهر إجابة غلط: «diamagnetic substance». ودي عكسها: كل الـ electrons فيها paired، وبتتنافر مع الـ field. وإجابة غلط تانية: «magnetic moment». ودي شدة الـ magnetism، مش المادة نفسها."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":29,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-moment-from-config-3","kind":"question","version":1,"ord":325,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.magnetic-moment-from-config","concepts":[{"concept_id":"te.magnetic-moment-from-config","role":"primary"}],"title":"chem-s3-en.question-te.magnetic-moment-from-config-3","payload":{"stem":"Give reasons: Copper(II) oxide, $\\ce{CuO}$, is a paramagnetic substance, while copper(I) oxide, $\\ce{Cu2O}$, is diamagnetic. ($_{29}$Cu)","tags":["exam-style","give-reasons","new-case"],"type":"short","bloom":"apply","answer":"Key points: (1) Cu is [Ar] 4s¹ 3d¹⁰. (2) In CuO copper is Cu²⁺: [Ar] 3d⁹, with 1 unpaired electron, so CuO is paramagnetic. (3) In Cu2O copper is Cu⁺: [Ar] 3d¹⁰, all electrons paired, magnetic moment zero, so Cu2O is diamagnetic.","book_ref":"Ch.1 magnetic properties, p.14; form of Evaluation Q7.9, p.27; Cu oxidation states (+1, +2)","difficulty":3,"concept_ids":["te.magnetic-moment-from-config"],"est_seconds":120},"layer":{"explanation":"Step 1: oxidation states. O is −2. In CuO one copper balances −2, so it is +2. In Cu2O two copper atoms share −2, so each is +1. Step 2: configurations, losing 4s first. Cu is [Ar] 4s¹ 3d¹⁰. Cu⁺ loses 4s¹: [Ar] 3d¹⁰. Cu²⁺ loses 4s¹ and one 3d: [Ar] 3d⁹. Step 3: boxes. 3d⁹ has four pairs and one unpaired electron: 1 unpaired, so CuO is attracted to the external field (paramagnetic). 3d¹⁰ has five pairs: 0 unpaired, magnetic moment zero, so Cu2O repels the field (diamagnetic). Most likely wrong answer: 'both are copper, so both behave the same'. The ion decides, not the element. Another: using Cu²⁺ for Cu2O because of the '2' in the formula."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"خطوة 1: الـ oxidation states. الـ O بـ −2. في الـ CuO ذرة copper واحدة بتعادل الـ −2، يعني هي +2. في الـ Cu2O ذرتين copper بيتقسموا الـ −2، يعني كل واحدة +1. خطوة 2: الـ configurations، والـ 4s بيفقد الأول. الـ Cu هو [Ar] 4s¹ 3d¹⁰. الـ Cu⁺ بيفقد الـ 4s¹: [Ar] 3d¹⁰. الـ Cu²⁺ بيفقد الـ 4s¹ وواحد من الـ 3d: [Ar] 3d⁹. خطوة 3: المربعات. الـ 3d⁹ فيه أربع أزواج وكمان electron واحد unpaired: يعني 1 unpaired، فالـ CuO بيتجذب للـ external field (paramagnetic). الـ 3d¹⁰ فيه خمس أزواج: يعني 0 unpaired، والـ magnetic moment بصفر، فالـ Cu2O بيتنافر مع الـ field (diamagnetic). أكتر إجابة غلط متوقعة: 'الاتنين copper، يبقى الاتنين زي بعض'. اللي بيحدد هو الـ ion، مش العنصر. وغلطة تانية: إنك تستخدم الـ Cu²⁺ في الـ Cu2O عشان الـ '2' اللي في الـ formula."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":30,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.catalytic-activity-3","kind":"question","version":2,"ord":326,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.catalytic-activity","concepts":[{"concept_id":"te.catalytic-activity","role":"primary"}],"title":"chem-s3-en.question-te.catalytic-activity-3","payload":{"stem":"Consider the following statements about a first transition metal used as a catalyst:\n(I) Its 4s and 3d electrons form bonds between its surface atoms and the reacting molecules.\n(II) It increases the net energy released by the reaction.\n(III) It weakens the bonds in the reactant molecules, so the activation energy decreases.\nWhich of these statements is/are correct?","tags":["exam-style","statements","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"(I) and (III) only","correct":true},{"id":"b","text":"(I), (II) and (III)","correct":false,"misconception_id":"te.catalytic-activity.mc2"},{"id":"c","text":"(II) and (III) only","correct":false},{"id":"d","text":"(III) only","correct":false}],"book_ref":"Ch.1 point 5 Catalytic activity, p.15 (fig 1-3)","difficulty":3,"concept_ids":["te.catalytic-activity"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right. Bonds to the surface weaken the reactant bonds and lower the barrier."},"b":{"why":"(II) is false: in fig 1-3 the reactant and product levels are the same with and without the catalyst, so the net energy released does not change.","feedback":"Misconception: A catalyst increases the energy released by the reaction."},"c":{"why":"This leaves out (I), which is true: the book says the 4s and 3d electrons form bonds between the surface atoms and the reacting molecules. It also accepts (II), which is false.","feedback":"Misconception: A catalyst works by changing the reaction's energy, not by bonding to the reactants."},"d":{"why":"(III) is right, but this leaves out (I), which is also true: the bonds that the 4s and 3d electrons form with the reacting molecules are what weaken the reactant bonds.","feedback":"Misconception: The surface bonding step is not part of how a catalyst works."}},"explanation":"(I) is correct: the book says the 4s and 3d electrons are used to form bonds between the surface atoms of the metal and the reacting molecules. This increases the concentration of these molecules on the surface. (III) is correct: these bonds weaken the bonds in the reactant molecules, so the activation energy decreases and the reaction speeds up. (II) is wrong: a catalyst does not change the energy of the reactants or products. In fig 1-3 the net energy released is the same with and without $\\ce{MnO2}$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ bonds مع السطح بتضعّف الـ bonds اللي في الـ reactants وبتوطّي الحاجز."},"b":{"why":"(II) غلط: في شكل 1-3 مستوى الـ reactants والـ products هو هو مع الـ catalyst ومن غيره، فالـ net energy released مابتتغيرش.","feedback":"الفكرة الغلط: إن الـ catalyst بيزوّد الـ energy اللي الـ reaction بيطلّعها."},"c":{"why":"كده إنت سبت (I)، وهي صح: الكتاب بيقول إن الـ 4s والـ 3d electrons بيكوّنوا bonds بين ذرات السطح والـ reacting molecules. وكمان قبلت (II)، وهي غلط.","feedback":"الفكرة الغلط: إن الـ catalyst بيشتغل بإنه يغيّر الـ energy بتاعة الـ reaction، مش بإنه يكوّن bonds مع الـ reactants."},"d":{"why":"(III) صح، لكن كده إنت سبت (I)، وهي صح كمان: الـ bonds اللي الـ 4s والـ 3d electrons بيكوّنوها مع الـ reacting molecules هي اللي بتضعّف الـ bonds اللي في الـ reactants.","feedback":"الفكرة الغلط: إن خطوة تكوين الـ bonds مع السطح مش جزء من طريقة شغل الـ catalyst."}},"explanation":"(I) صح: الكتاب بيقول إن الـ 4s والـ 3d electrons بتتستخدم في تكوين bonds بين ذرات سطح الـ metal والـ reacting molecules، وده بيزوّد الـ concentration بتاع الـ molecules دي على السطح. (III) صح: الـ bonds دي بتضعّف الـ bonds اللي في الـ reactant molecules، فالـ activation energy بتقل والـ reaction بيسرع. (II) غلط: الـ catalyst مابيغيّرش الـ energy بتاعة الـ reactants ولا الـ products. في شكل 1-3 الـ net energy released هي هي مع الـ $\\ce{MnO2}$ ومن غيره."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":31,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.catalysis-examples-3","kind":"question","version":1,"ord":327,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.catalysis-examples","concepts":[{"concept_id":"te.catalysis-examples","role":"primary"}],"title":"chem-s3-en.question-te.catalysis-examples-3","payload":{"stem":"The diagram shows the preparation of sulphuric acid by the contact method. Write the balanced equation of step (1), naming its catalyst over the arrow with the temperature.","tags":["exam-style","write-the-equation","diagram","equation"],"type":"short","bloom":"apply","answer":"\\ce{2SO2(g) + O2(g) ->[V2O5 / 450\\,^{\\circ}C] 2SO3(g)}","figure":{"root":"f","elements":{"f":{"type":"FlowDiagram","props":{"edges":[{"to":"b","from":"a","label":"(1) + O₂, catalyst ?, 450 °C"},{"to":"c","from":"b","label":"(2) + H₂O"}],"nodes":[{"id":"a","label":"SO₂(g)"},{"id":"b","label":"SO₃"},{"id":"c","label":"H₂SO₄(aq)"}],"layout":"horizontal","caption":"Preparation of sulphuric acid by the contact method"},"children":[]}}},"book_ref":"Ch.1 point 5 Catalytic activity, contact method, p.15","difficulty":3,"concept_ids":["te.catalysis-examples"],"est_seconds":120},"layer":{"explanation":"Step (1) oxidizes sulphur dioxide to sulphur trioxide. The catalyst is vanadium pentoxide, $\\ce{V2O5}$, at 450 °C, written over the arrow. Balance it: $\\ce{2SO2}$ has 2 S and 4 O; adding $\\ce{O2}$ gives 6 O, which make $\\ce{2SO3}$. Step (2) then is: $\\ce{SO3 + H2O -> H2SO4}$. Grader looks for: coefficients 2, 1, 2; $\\ce{V2O5}$ and 450 °C over the arrow; not $\\ce{V2O5}$ as a reactant. Most likely wrong answer: writing Fe as the catalyst (that belongs to the Haber-Bosch method), or writing $\\ce{SO2 + O2 -> SO3}$ unbalanced."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الخطوة (1) بتأكسد الـ sulphur dioxide لـ sulphur trioxide. الـ catalyst هو الـ vanadium pentoxide، يعني $\\ce{V2O5}$، عند 450 °C، وبيتكتب فوق السهم. وازنها: الـ $\\ce{2SO2}$ فيهم 2 S و4 O؛ ولما تضيف $\\ce{O2}$ يبقى عندك 6 O، ودول بيعملوا $\\ce{2SO3}$. وبعدها الخطوة (2) بتبقى: $\\ce{SO3 + H2O -> H2SO4}$. المصحح بيدور على: الـ coefficients 2، 1، 2؛ الـ $\\ce{V2O5}$ و450 °C فوق السهم؛ ومش الـ $\\ce{V2O5}$ كـ reactant. أشهر غلطة: إنك تكتب الـ Fe كـ catalyst (ده بتاع الـ Haber-Bosch method)، أو تكتب $\\ce{SO2 + O2 -> SO3}$ من غير ما توزنها."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":32,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-properties-4","kind":"question","version":1,"ord":328,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.magnetic-properties","concepts":[{"concept_id":"te.magnetic-properties","role":"primary"}],"title":"chem-s3-en.question-te.magnetic-properties-4","payload":{"stem":"Substance A is attracted to an external magnetic field. Substance B is repelled by it. Which comparison between A and B is correct?","tags":["exam-style","compare","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"A has unpaired electrons; in B all electrons are paired, so the magnetic moment of B is zero.","correct":true},{"id":"b","text":"A is a permanent magnet; B is not affected by the magnetic field at all.","correct":false},{"id":"c","text":"A has more electrons in total than B, so the magnetic moment of A is larger.","correct":false},{"id":"d","text":"In A all electrons are paired; B has unpaired electrons that push the field away.","correct":false}],"book_ref":"Ch.1 general properties, point 4 (a, b), pp.13-14","difficulty":3,"concept_ids":["te.magnetic-properties"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right. Unpaired spins form a field; paired opposite spins cancel."},"b":{"why":"Two slips: A is attracted only while it is in the external field, so it is not a permanent magnet, and B moves away from the field, so it is affected: it is repelled.","feedback":"Misconception: Paramagnetic means a magnet, and diamagnetic means not affected."},"c":{"why":"Zinc has more electrons than iron, yet zinc is not attracted: the unpaired electrons decide the magnetic moment, not the total number of electrons.","feedback":"Misconception: More electrons means more magnetic."},"d":{"why":"Unpaired spinning electrons form their own magnetic field, which causes attraction to the external field, so the attracted substance A is the one with unpaired electrons.","feedback":"Misconception: Unpaired electrons cause repulsion."}},"explanation":"A is paramagnetic: it has unpaired electrons. Each spinning unpaired electron forms a small magnetic field, so A is attracted to the external magnetic field. Its magnetic moment increases with the number of unpaired electrons. B is diamagnetic: all its electrons are paired with opposite spins, so their fields cancel. Its magnetic moment equals zero and it repels the external field. A paramagnetic substance is not a magnet: it is attracted only while in an external field. The total number of electrons does not decide; only unpaired electrons count."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ unpaired spins بتعمل field، والـ opposite spins اللي في أزواج بتلغي بعض."},"b":{"why":"فيه غلطتين هنا: الـ A بتتجذب طول ما هي جوه الـ external field بس، فهي مش permanent magnet. والـ B بتتنافر مع الـ field، وده تأثير، مش «مش بتتأثر».","feedback":"الفكرة الغلط: إن الـ paramagnetic يعني magnet، والـ diamagnetic يعني مش بتتأثر."},"c":{"why":"الـ zinc عنده electrons أكتر من الـ iron، ومع ذلك الـ zinc مش بيتجذب. الـ unpaired electrons هي اللي بتحدد الـ magnetic moment، مش العدد الكلي للـ electrons.","feedback":"الفكرة الغلط: إن electrons أكتر يعني magnetic أكتر."},"d":{"why":"الـ unpaired electrons وهي بتلف بتعمل magnetic field خاص بيها، والـ field ده بيعمل جذب، مش تنافر. فالمادة اللي فيها unpaired electrons هي اللي بتتجذب.","feedback":"الفكرة الغلط: إن الـ unpaired electrons هي اللي بتعمل التنافر."}},"explanation":"الـ A هي paramagnetic: فيها unpaired electrons. كل unpaired electron وهو بيلف بيعمل magnetic field صغير، فالـ A بتتجذب للـ external magnetic field. والـ magnetic moment بتاعها بيزيد مع عدد الـ unpaired electrons. أما الـ B فهي diamagnetic: كل الـ electrons بتاعتها paired بـ opposite spins، فالـ fields بتاعتهم بتلغي بعض. الـ magnetic moment بتاعها بيساوي صفر، وبتتنافر مع الـ external field. الـ paramagnetic substance مش magnet: هي بتتجذب طول ما هي جوه external field وبس. والعدد الكلي للـ electrons مش هو اللي بيحدد؛ الـ unpaired electrons تحديدًا هما اللي بيفرقوا."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":33,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-moment-from-config-4","kind":"question","version":1,"ord":329,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.magnetic-moment-from-config","concepts":[{"concept_id":"te.magnetic-moment-from-config","role":"primary"},{"concept_id":"te.ion-configuration","role":"secondary"}],"title":"chem-s3-en.question-te.magnetic-moment-from-config-4","payload":{"stem":"The ion $\\ce{M^3+}$ of an element M in the first transition series has 4 unpaired electrons in its 3d sublevel (filled by Hund's rule). Which element(s) could M be? ($_{24}$Cr, $_{25}$Mn, $_{26}$Fe, $_{27}$Co)","tags":["exam-style","two-step","choose"],"type":"mcq","bloom":"analyze","choices":[{"id":"a","text":"Mn or Co","correct":true},{"id":"b","text":"Mn only","correct":false},{"id":"c","text":"Fe only","correct":false},{"id":"d","text":"Co only","correct":false}],"book_ref":"Ch.1 magnetic properties, p.14; ion configurations, pp.8-9","difficulty":5,"concept_ids":["te.magnetic-moment-from-config","te.ion-configuration"],"est_seconds":150},"layer":{"choices":{"a":{"why":"Right. Mn³⁺ is 3d⁴ and Co³⁺ is 3d⁶: both have 4 unpaired."},"b":{"why":"Mn³⁺ works, but a 3d sublevel with more than four electrons can also leave four unpaired: 3d⁶ has one pair plus 4 unpaired.","feedback":"Misconception: The number of unpaired electrons equals the number of d electrons."},"c":{"why":"The iron atom has 3d⁶, but Fe³⁺ keeps five 3d electrons, all unpaired, so it has 5, not 4.","feedback":"Misconception: Counts the unpaired electrons of the atom instead of the ion."},"d":{"why":"4s electrons leave first; with that order, Mn³⁺ (3d⁴) also has 4 unpaired electrons, so Co is not the single fit.","feedback":"Misconception: Ions lose 3d electrons before 4s (Co 4s² 3d⁷ → 4s² 3d⁴)."}},"explanation":"Write each M³⁺ ion, losing 4s electrons first. Cr is [Ar] 4s¹ 3d⁵, so Cr³⁺ is 3d³: 3 unpaired. Mn is [Ar] 4s² 3d⁵, so Mn³⁺ is 3d⁴: 4 unpaired. Fe is [Ar] 4s² 3d⁶, so Fe³⁺ is 3d⁵: 5 unpaired. Co is [Ar] 4s² 3d⁷, so Co³⁺ is 3d⁶: one pair plus 4 unpaired electrons. So two ions fit: Mn³⁺ and Co³⁺. Lesson: different numbers of d electrons can give the same number of unpaired electrons (d⁴ and d⁶). After five electrons, the boxes start pairing."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ Mn³⁺ هو 3d⁴ والـ Co³⁺ هو 3d⁶: الاتنين فيهم 4 unpaired."},"b":{"why":"الـ Mn³⁺ ماشي، لكن 3d sublevel فيه أكتر من أربعة electrons ممكن برضه يسيب أربعة unpaired: الـ 3d⁶ فيه زوج واحد و4 unpaired.","feedback":"الفكرة الغلط: إن عدد الـ unpaired electrons بيساوي عدد الـ d electrons."},"c":{"why":"ذرة الـ iron فيها 3d⁶، لكن الـ Fe³⁺ بيفضل معاه خمسة 3d electrons كلهم unpaired، يعني 5 مش 4.","feedback":"الفكرة الغلط: إنك تعدّ الـ unpaired electrons بتوع الذرة بدل الـ ion."},"d":{"why":"الـ 4s electrons بتمشي الأول؛ وبالترتيب ده الـ Mn³⁺ (3d⁴) كمان فيه 4 unpaired electrons، فالـ Co مش هو الوحيد اللي ينفع.","feedback":"الفكرة الغلط: إن الـ ions بتفقد الـ 3d electrons قبل الـ 4s (Co 4s² 3d⁷ → 4s² 3d⁴)."}},"explanation":"اكتب كل M³⁺ ion، والـ 4s electrons بتمشي الأول. الـ Cr هو [Ar] 4s¹ 3d⁵، فالـ Cr³⁺ هو 3d³: يعني 3 unpaired. الـ Mn هو [Ar] 4s² 3d⁵، فالـ Mn³⁺ هو 3d⁴: يعني 4 unpaired. الـ Fe هو [Ar] 4s² 3d⁶، فالـ Fe³⁺ هو 3d⁵: يعني 5 unpaired. الـ Co هو [Ar] 4s² 3d⁷، فالـ Co³⁺ هو 3d⁶: زوج واحد و4 unpaired electrons. يبقى فيه اتنين ions ينفعوا: الـ Mn³⁺ والـ Co³⁺. الدرس هنا: أعداد مختلفة من الـ d electrons ممكن تدّي نفس عدد الـ unpaired electrons (الـ d⁴ والـ d⁶). بعد خمس electrons، المربعات بتبدأ تعمل أزواج."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":34,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.notes","section_title":"Filling of 3d, anomalies of Cr and Cu, oxidation states","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Filling of 3d, anomalies of Cr and Cu, oxidation states"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.catalytic-activity-4","kind":"question","version":2,"ord":330,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.catalytic-activity","concepts":[{"concept_id":"te.catalytic-activity","role":"primary"}],"title":"chem-s3-en.question-te.catalytic-activity-4","payload":{"stem":"Iron is used as a catalyst in the Haber-Bosch method. Compared with the same reaction without iron, which quantity is smaller when iron is present?","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"The activation energy of the reaction","correct":true},{"id":"b","text":"The net energy released by the reaction","correct":false,"misconception_id":"te.catalytic-activity.mc2"},{"id":"c","text":"The concentration of reacting molecules on the iron surface","correct":false},{"id":"d","text":"The mass of iron at the end of the reaction","correct":false,"misconception_id":"te.catalytic-activity.mc1"}],"book_ref":"Ch.1 point 5 Catalytic activity, Haber-Bosch, p.15","difficulty":2,"concept_ids":["te.catalytic-activity"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right. Iron lowers the barrier, so the reaction is faster."},"b":{"why":"A catalyst does not move the reactant or product levels, so the net energy released stays the same.","feedback":"Misconception: A catalyst changes the energy released by the reaction."},"c":{"why":"The surface bonds hold the reacting molecules, so their concentration on the surface rises.","feedback":"Misconception: A catalyst surface pushes reactant molecules away."},"d":{"why":"A catalyst is not used up, so the mass of iron is unchanged. Iron is written over the arrow, not before it.","feedback":"Misconception: A catalyst is used up in the reaction."}},"explanation":"Iron's 4s and 3d electrons form bonds with the $\\ce{N2}$ and $\\ce{H2}$ molecules on its surface. This raises their concentration on the surface and weakens their bonds. So the activation energy decreases and ammonia forms faster. The net energy released stays the same, because the reactants and products are the same. The iron is not used up, so its mass at the end is unchanged. That is why Fe is written over the arrow."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ iron بيوطّي الحاجز، فالـ reaction بيبقى أسرع."},"b":{"why":"الـ catalyst مابيحرّكش مستوى الـ reactants ولا الـ products، فالـ net energy released بتفضل زي ما هي.","feedback":"الفكرة الغلط: إن الـ catalyst بيغيّر الـ energy اللي الـ reaction بيطلّعها."},"c":{"why":"الـ bonds اللي مع السطح بتمسك الـ reacting molecules، فالـ concentration بتاعتها على السطح بتزيد.","feedback":"الفكرة الغلط: إن سطح الـ catalyst بيزق الـ reactant molecules بعيد."},"d":{"why":"الـ catalyst مابيتستهلكش، فكتلة الـ iron مابتتغيرش. الـ iron مكتوب فوق السهم، مش قبله.","feedback":"الفكرة الغلط: إن الـ catalyst بيتستهلك في الـ reaction."}},"explanation":"الـ 4s والـ 3d electrons بتوع الـ iron بيكوّنوا bonds مع الـ $\\ce{N2}$ والـ $\\ce{H2}$ molecules على سطحه. ده بيزوّد الـ concentration بتاعهم على السطح وبيضعّف الـ bonds اللي فيهم. فالـ activation energy بتقل والـ ammonia بتتكوّن أسرع. والـ net energy released بتفضل زي ما هي، عشان الـ reactants والـ products هما هما. والـ iron مابيتستهلكش، فكتلته في الآخر مابتتغيرش. وعشان كده الـ Fe بيتكتب فوق السهم."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":35,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-moment-from-config-5","kind":"question","version":1,"ord":331,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.magnetic-moment-from-config","concepts":[{"concept_id":"te.magnetic-moment-from-config","role":"primary"}],"title":"chem-s3-en.question-te.magnetic-moment-from-config-5","payload":{"stem":"Which of the following compounds is diamagnetic? ($_{21}$Sc, $_{23}$V, $_{26}$Fe, $_{29}$Cu)","tags":["exam-style","choose","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$\\ce{Sc2(SO4)3}$","correct":true},{"id":"b","text":"$\\ce{CuCl2}$","correct":false},{"id":"c","text":"$\\ce{FeSO4}$","correct":false},{"id":"d","text":"$\\ce{VCl4}$","correct":false}],"book_ref":"Ch.1 magnetic properties, p.14; Evaluation Q4 form, p.26","difficulty":3,"concept_ids":["te.magnetic-moment-from-config"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right. Sc³⁺ has no 3d electrons, so none is unpaired."},"b":{"why":"The copper atom has a full 3d¹⁰, but copper here is +2, and Cu²⁺ is 3d⁹ with 1 unpaired electron.","feedback":"Misconception: Uses the full 3d¹⁰ of the copper atom instead of Cu²⁺."},"c":{"why":"By Hund's rule each box takes one electron first, so Fe²⁺ (3d⁶) has 4 unpaired electrons, not three pairs.","feedback":"Misconception: Pairs electrons before every box has one (d⁶ = three pairs)."},"d":{"why":"V⁴⁺ keeps one 3d electron, and that electron has no partner, so it is unpaired.","feedback":"Misconception: One unpaired electron is too few to make a substance paramagnetic."}},"explanation":"Find each metal ion and count unpaired electrons. Sc2(SO4)3: sulphate is −2, so Sc is +3; Sc³⁺ is [Ar] 3d⁰: 0 unpaired, diamagnetic. CuCl2: Cu²⁺ is [Ar] 3d⁹: 1 unpaired. FeSO4: Fe²⁺ is [Ar] 3d⁶: 4 unpaired. VCl4: V⁴⁺ is [Ar] 3d¹: 1 unpaired. Any unpaired electron, even one, makes a substance paramagnetic. Being a transition element does not make every compound paramagnetic: the ion decides."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ Sc³⁺ مفيهوش 3d electrons، فمفيش ولا واحد unpaired."},"b":{"why":"ذرة الـ copper فيها 3d¹⁰ كامل، لكن الـ copper هنا بـ +2، والـ Cu²⁺ بيبقى 3d⁹ وفيه 1 unpaired electron.","feedback":"الفكرة الغلط: إنك تستخدم الـ 3d¹⁰ الكامل بتاع ذرة الـ copper بدل الـ Cu²⁺."},"c":{"why":"حسب الـ Hund's rule كل مربع بياخد electron واحد الأول، فالـ Fe²⁺ (3d⁶) فيه 4 unpaired electrons، مش تلات أزواج.","feedback":"الفكرة الغلط: إنك تعمل أزواج قبل ما كل مربع ياخد electron (d⁶ = تلات أزواج)."},"d":{"why":"الـ V⁴⁺ بيفضل معاه 3d electron واحد بس، والـ electron ده مالوش شريك، فهو unpaired.","feedback":"الفكرة الغلط: إن unpaired electron واحد قليل عشان يخلّي المادة paramagnetic."}},"explanation":"هات كل metal ion وعدّ الـ unpaired electrons. الـ Sc2(SO4)3: الـ sulphate بـ −2، يعني الـ Sc بـ +3؛ والـ Sc³⁺ هو [Ar] 3d⁰: يعني 0 unpaired، فهو diamagnetic. الـ CuCl2: الـ Cu²⁺ هو [Ar] 3d⁹: يعني 1 unpaired. الـ FeSO4: الـ Fe²⁺ هو [Ar] 3d⁶: يعني 4 unpaired. الـ VCl4: الـ V⁴⁺ هو [Ar] 3d¹: يعني 1 unpaired. أي unpaired electron، حتى لو واحد، بيخلّي المادة paramagnetic. وكون العنصر transition element مش معناه إن كل الـ compounds بتاعته paramagnetic: اللي بيحدد هو الـ ion."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":36,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.fe2-fe3-mn2-stability-5","kind":"question","version":1,"ord":332,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.fe2-fe3-mn2-stability","concepts":[{"concept_id":"te.fe2-fe3-mn2-stability","role":"primary"},{"concept_id":"te.magnetic-moment-from-config","role":"secondary"}],"title":"chem-s3-en.question-te.fe2-fe3-mn2-stability-5","payload":{"stem":"An iron(II) compound is easily oxidized to an iron(III) compound. Which statement gives the reason, and the change in the number of unpaired electrons? ($_{26}$Fe)","tags":["mixed","retrieval","choose","reason"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$\\ce{Fe^3+}$ has a half-filled $3d^5$ sublevel, so it is more stable; unpaired electrons increase from 4 to 5.","correct":true},{"id":"b","text":"$\\ce{Fe^3+}$ has a half-filled $3d^5$ sublevel, so it is more stable; unpaired electrons decrease from 6 to 5.","correct":false},{"id":"c","text":"$\\ce{Fe^3+}$ has an empty $4s$ sublevel, so it is more stable; unpaired electrons increase from 4 to 5.","correct":false},{"id":"d","text":"$\\ce{Fe^3+}$ has a higher charge, so it holds its electrons more tightly; unpaired electrons increase from 4 to 5.","correct":false}],"book_ref":"Ch.1 oxidation states, Fe(II) to Fe(III) and Mn(II) diagrams, p.9; magnetic properties, p.14","difficulty":3,"concept_ids":["te.fe2-fe3-mn2-stability","te.magnetic-moment-from-config"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right. 3d⁶ has 4 unpaired; 3d⁵ has 5, one per box."},"b":{"why":"The reason is right, but the six electrons of 3d⁶ cannot all be unpaired in five boxes: one pair forms, leaving 4 unpaired.","feedback":"Misconception: The number of unpaired electrons equals the number of d electrons."},"c":{"why":"Fe²⁺ has already lost both 4s electrons, so the empty 4s is not the reason; the change is in the 3d sublevel, which becomes half-filled.","feedback":"Misconception: Losing the 4s electrons is what makes the ion stable."},"d":{"why":"Then Mn³⁺ would beat Mn²⁺, but the book says Mn²⁺ is more stable: Fe³⁺ and Mn²⁺ share a half-filled 3d⁵, and that is the reason.","feedback":"Misconception: A higher charge always makes an ion more stable."}},"explanation":"Fe²⁺ is [Ar] 3d⁶: one pair and four unpaired electrons. When it loses one more electron, it becomes Fe³⁺, [Ar] 3d⁵. This 3d sublevel is half-filled, which is more stable. So iron(II) is easily oxidized to iron(III). 3d⁵ has one electron in each box: 5 unpaired. So the magnetic moment increases. The reason is the half-filled 3d⁵, not the charge: Mn²⁺ (3d⁵) is more stable than Mn³⁺ (3d⁴). The empty 4s is not the reason either, because Fe²⁺ already has an empty 4s."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ 3d⁶ فيه 4 unpaired؛ والـ 3d⁵ فيه 5، واحد في كل مربع."},"b":{"why":"السبب صح، لكن الستة electrons بتوع الـ 3d⁶ مايقدروش يبقوا كلهم unpaired في خمس مربعات: بيتكوّن زوج واحد، ويفضل 4 unpaired.","feedback":"الفكرة الغلط: إن عدد الـ unpaired electrons بيساوي عدد الـ d electrons."},"c":{"why":"الـ Fe²⁺ خسر الاتنين 4s electrons خلاص، فالـ 4s الفاضي مش هو السبب؛ التغيير بيحصل في الـ 3d sublevel، اللي بيبقى half-filled.","feedback":"الفكرة الغلط: إن خسارة الـ 4s electrons هي اللي بتخلّي الـ ion مستقر."},"d":{"why":"لو كده، كان الـ Mn³⁺ هيبقى أكتر استقرارًا من الـ Mn²⁺، لكن الكتاب بيقول إن الـ Mn²⁺ أكتر استقرارًا: الـ Fe³⁺ والـ Mn²⁺ الاتنين عندهم 3d⁵ half-filled، وده هو السبب.","feedback":"الفكرة الغلط: إن الـ charge الأعلى دايمًا بيخلّي الـ ion أكتر استقرارًا."}},"explanation":"الـ Fe²⁺ تركيبه [Ar] 3d⁶: زوج واحد وأربعة unpaired electrons. لما يخسر electron كمان بيبقى Fe³⁺، [Ar] 3d⁵. الـ 3d sublevel ده نصه مليان، وده أكتر استقرارًا. وعشان كده الـ iron(II) بيتأكسد بسهولة لـ iron(III). الـ 3d⁵ فيه electron واحد في كل مربع: 5 unpaired. فالـ magnetic moment بيزيد. السبب هو الـ 3d⁵ اللي نصه مليان، مش الـ charge: الـ Mn²⁺ (3d⁵) أكتر استقرارًا من الـ Mn³⁺ (3d⁴). والـ 4s الفاضي برضه مش هو السبب، لأن الـ Fe²⁺ الـ 4s بتاعه فاضي أصلًا."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":71,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":13,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.atomic-radius-5","kind":"question","version":1,"ord":333,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.atomic-radius","concepts":[{"concept_id":"te.atomic-radius","role":"primary"}],"title":"chem-s3-en.question-te.atomic-radius-5","payload":{"stem":"Look at the highlighted part of the graph, from Cr to Cu. The book links this part to the use of these metals in making alloys (an alloy is a metal mixed with other elements; you will study alloys later). Which statement describes and explains this part?","tags":["mixed","retrieval","read-the-graph"],"type":"mcq","bloom":"understand","figure":{"root":"c","elements":{"c":{"type":"Chart","props":{"kind":"line","series":[{"name":"Atomic radius","points":[{"x":"Sc","y":1.44},{"x":"Ti","y":1.32},{"x":"V","y":1.22},{"x":"Cr","y":1.17},{"x":"Mn","y":1.17},{"x":"Fe","y":1.16},{"x":"Co","y":1.16},{"x":"Ni","y":1.15},{"x":"Cu","y":1.17}]}],"caption":"Book's table, p.12 (for illustration only)","x_label":"Element","y_label":"Atomic radius","highlight":["Cr","Mn","Fe","Co","Ni","Cu"]},"children":[]}}},"choices":[{"id":"a","text":"The atomic radius is nearly constant, because two opposite factors balance.","correct":true},{"id":"b","text":"The atomic radius is nearly constant, because the number of 3d electrons does not change from Cr to Cu.","correct":false},{"id":"c","text":"The atomic radius decreases sharply, because the effective nuclear charge increases while nothing opposes it.","correct":false},{"id":"d","text":"The atomic radius increases, because the atomic mass increases from Cr to Cu.","correct":false}],"book_ref":"Ch.1 general properties, point 2 Atomic radius + data table, pp.12-13","difficulty":2,"concept_ids":["te.atomic-radius"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right. Their similar sizes are why the book links them to making alloys."},"b":{"why":"Cr has 3d⁵ and Cu has 3d¹⁰, so the number of 3d electrons rises.","feedback":"Misconception: Nothing changes in the electron structure across this part of the series."},"c":{"why":"The values are 1.17, 1.17, 1.16, 1.16, 1.15, 1.17: that is not a sharp fall.","feedback":"Misconception: Only the nuclear charge affects the radius."},"d":{"why":"Mass sits in the tiny nucleus, and a heavier nucleus does not make the atom bigger. The values do not rise either.","feedback":"Misconception: Heavier atoms are bigger."}},"explanation":"From Cr to Cu the radius stays near 1.15–1.17. The book explains this with two opposite factors. The effective nuclear charge increases, which pulls the electrons in and decreases the radius. The number of 3d electrons also increases, so their repulsion increases, which increases the radius. The two factors balance, so the radii are relatively constant. The book adds that this explains using these elements in making alloys. Atomic mass does not decide the size."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. أحجامهم المتقاربة هي السبب إن الكتاب بيربطهم بعمل الـ alloys."},"b":{"why":"الـ Cr عنده 3d⁵ والـ Cu عنده 3d¹⁰، فعدد الـ 3d electrons بيزيد.","feedback":"الفكرة الغلط: إن مفيش حاجة بتتغيّر في ترتيب الـ electrons في الجزء ده من السلسلة."},"c":{"why":"القيم: 1.17، 1.17، 1.16، 1.16، 1.15، 1.17. ده مش نزول حاد.","feedback":"الفكرة الغلط: إن الـ nuclear charge لوحدها هي اللي بتأثر على الـ radius."},"d":{"why":"الكتلة متركّزة في الـ nucleus الصغيرة جدًا، والـ nucleus الأتقل مابتكبّرش الذرة. والقيم كمان مابتطلعش.","feedback":"الفكرة الغلط: إن الذرات الأتقل أكبر."}},"explanation":"من الـ Cr للـ Cu الـ radius بيفضل حوالين 1.15–1.17. الكتاب بيفسّر ده بعاملين عكس بعض: الـ effective nuclear charge بتزيد، فبتشد الـ electrons لجوّه وبتصغّر الـ radius؛ وعدد الـ 3d electrons كمان بيزيد، فالتنافر بينهم بيزيد وبيكبّر الـ radius. العاملين بيوازنوا بعض، فقيم الـ radius ثابتة نسبيًا. والكتاب بيضيف إن ده بيفسّر استخدام العناصر دي في عمل الـ alloys. الـ atomic mass مش هي اللي بتحدد الحجم."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":40,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-ni-4","kind":"question","version":1,"ord":334,"group_id":"chem-s3-en.ch1.practice.te-magnetism-catalysis","primary_concept_id":"te.uses-ni","concepts":[{"concept_id":"te.uses-ni","role":"primary"},{"concept_id":"te.catalytic-activity","role":"secondary"}],"title":"chem-s3-en.question-te.uses-ni-4","payload":{"stem":"Finely divided nickel is used as a catalyst in the hydrogenation of oils. How does the nickel speed up this reaction, according to the book?","tags":["mixed","retrieval","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Its 4s and 3d electrons bond the reacting molecules to its surface, which weakens their bonds.","correct":true},{"id":"b","text":"It reacts with the hydrogen and becomes part of the solid fat that forms.","correct":false},{"id":"c","text":"It gives the oil and hydrogen molecules extra heat energy to react.","correct":false},{"id":"d","text":"It increases the amount of fat that forms from the same amount of oil.","correct":false}],"book_ref":"Ch.1 economic importance: nickel, p.7; point 5 Catalytic activity, pp.14-15","difficulty":3,"concept_ids":["te.uses-ni","te.catalytic-activity"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right. Weaker bonds mean a lower activation energy."},"b":{"why":"If nickel became part of the fat, it would be used up, and a catalyst is not used up.","feedback":"Misconception: A catalyst is used up and becomes part of the product."},"c":{"why":"A catalyst does not supply energy: it lowers the barrier (the activation energy) instead of pushing the molecules over it.","feedback":"Misconception: A catalyst supplies energy to the reacting molecules."},"d":{"why":"The same oil and hydrogen give the same fat: a catalyst changes the speed, not the amount.","feedback":"Misconception: A catalyst increases the amount of product."}},"explanation":"Nickel is a transition element. Its 4s and 3d electrons form bonds between its surface atoms and the reacting molecules (oil and hydrogen). This increases their concentration on the surface and weakens their bonds. So the activation energy decreases and hydrogenation is faster. Finely divided means a fine powder with a large surface. The nickel is not used up, gives no energy, and does not change the amount of fat formed."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح. الـ bonds الأضعف معناها activation energy أقل."},"b":{"why":"لو الـ nickel بقى جزء من الـ fat، يبقى اتستهلك، والـ catalyst مابيتستهلكش.","feedback":"الفكرة الغلط: إن الـ catalyst بيتستهلك وبيبقى جزء من الـ product."},"c":{"why":"الـ catalyst مابيدّيش طاقة: هو بيوطّي الحاجز (الـ activation energy)، مش بيزق الـ molecules فوقه.","feedback":"الفكرة الغلط: إن الـ catalyst بيدّي طاقة للـ molecules اللي بتتفاعل."},"d":{"why":"نفس الـ oil ونفس الـ hydrogen بيدّوا نفس الـ fat. الـ catalyst بيغيّر السرعة، مش الكمية.","feedback":"الفكرة الغلط: إن الـ catalyst بيزوّد كمية الـ product."}},"explanation":"الـ nickel ده transition element. الـ 4s والـ 3d electrons بتوعه بيكوّنوا bonds بين الذرات اللي على سطحه والـ molecules اللي بتتفاعل (الـ oil والـ hydrogen). ده بيزوّد تركيزهم على السطح وبيضعّف الـ bonds بتاعتهم. فالـ activation energy بتقل والـ hydrogenation بيبقى أسرع. كلمة finely divided معناها powder ناعم ليه سطح كبير. والـ nickel مابيتستهلكش، ومابيدّيش طاقة، ومابيغيّرش كمية الـ fat اللي بتتكوّن."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":79,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":15,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":14,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.elements-compounds-mixtures-1","kind":"question","version":2,"ord":365,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"chem.elements-compounds-mixtures","concepts":[{"concept_id":"chem.elements-compounds-mixtures","role":"primary"}],"title":"chem-s3-en.question-chem.elements-compounds-mixtures-1","payload":{"stem":"Which of the following is a compound?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Magnesium oxide, $\\ce{MgO}$","correct":true},{"id":"b","text":"Oxygen gas, $\\ce{O2}$","correct":false},{"id":"c","text":"Sand mixed with salt","correct":false},{"id":"d","text":"Iron, $\\ce{Fe}$","correct":false}],"book_ref":"Prerequisite (preparatory science); used in Ch.1 'IRON', p.16 (ores = iron compounds (mostly oxides) mixed with impurities)","difficulty":1,"concept_ids":["chem.elements-compounds-mixtures"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right: MgO is two kinds of atom, Mg and O, chemically combined in a fixed ratio (1 : 1), so it is a compound."},"b":{"why":"This molecule has two atoms, but only one kind of atom, so $\\ce{O2}$ is an element.","feedback":"Misconception: A formula with two atoms is a compound."},"c":{"why":"The sand and the salt are not bonded to each other, and you could add more or less salt. That makes it a mixture.","feedback":"Misconception: Anything made of more than one substance is a compound."},"d":{"why":"Fe contains only one kind of atom, so it is an element.","feedback":"Misconception: Any pure substance is a compound."}},"explanation":"A compound is two or more elements chemically combined in a fixed ratio. MgO has two kinds of atom, Mg and O, bonded 1 : 1. $\\ce{O2}$ and Fe each contain one kind of atom, so they are elements. Sand with salt is a mixture: nothing is bonded, and the amounts can vary. Common slip: calling $\\ce{O2}$ a compound because its molecule has two atoms."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ MgO فيه نوعين من الذرات، Mg و O، متحدين كيميائيًا بنسبة ثابتة (1 : 1)، يبقى compound."},"b":{"why":"الـ molecule دي فيها ذرتين، لكن الاتنين من نوع واحد، فالـ $\\ce{O2}$ من الـ elements، مش compound.","feedback":"الفكرة الغلط: إن الـ formula اللي فيها ذرتين تبقى compound."},"c":{"why":"الرمل والملح مش مرتبطين ببعض، وتقدر تزوّد الملح أو تقلّله، يبقى ده mixture.","feedback":"الفكرة الغلط: إن أي حاجة متكوّنة من أكتر من مادة تبقى compound."},"d":{"why":"الـ Fe فيه نوع واحد من الذرات، يبقى من الـ elements، مش compound.","feedback":"الفكرة الغلط: إن أي pure substance يبقى compound."}},"explanation":"الـ compound هو اتنين elements أو أكتر متحدين كيميائيًا بنسبة ثابتة. الـ MgO فيه نوعين من الذرات، Mg و O، مرتبطين بنسبة 1 : 1. أما الـ $\\ce{O2}$ والـ Fe فكل واحد فيهم فيه نوع واحد من الذرات، يبقى دول elements. والرمل مع الملح ده mixture: مفيش حاجة مرتبطة ببعض، والكميات ممكن تختلف. غلطة بتتكرر: إنك تقول على الـ $\\ce{O2}$ إنه compound عشان الـ molecule بتاعته فيها ذرتين."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":22,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.elements-compounds-mixtures-2","kind":"question","version":2,"ord":366,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"chem.elements-compounds-mixtures","concepts":[{"concept_id":"chem.elements-compounds-mixtures","role":"primary"}],"title":"chem-s3-en.question-chem.elements-compounds-mixtures-2","payload":{"stem":"An iron ore contains iron compounds (mostly oxides) mixed with impurities. Which observation shows that an iron ore is a mixture, not a compound?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Its iron percentage differs from one deposit to another, and some impurities can be separated by physical means.","correct":true},{"id":"b","text":"It contains more than one element.","correct":false},{"id":"c","text":"It contains iron chemically combined with oxygen.","correct":false},{"id":"d","text":"It is a solid with a definite colour.","correct":false}],"book_ref":"Prerequisite (preparatory science); used in Ch.1 'IRON', p.16 (ores = iron compounds (mostly oxides) mixed with impurities)","difficulty":2,"concept_ids":["chem.elements-compounds-mixtures"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Right: a compound has a fixed composition. A changing iron percentage and impurities that can be removed by physical means are signs of a mixture."},"b":{"why":"Iron oxide alone contains two elements, and it is a compound. So the number of elements does not decide; a mixture is shown by a changing composition and physical separation.","feedback":"Misconception: Containing several elements makes a substance a mixture."},"c":{"why":"Chemical combination in a fixed ratio describes a compound. A mixture is shown by signs of physical mixing.","feedback":"Misconception: Chemical combination is a sign of a mixture."},"d":{"why":"Compounds and mixtures can both be coloured solids. A mixture is shown by a composition that can vary and parts that separate by physical means.","feedback":"Misconception: State or colour decides mixture or compound."}},"explanation":"A compound has a fixed ratio, so its composition never changes. A mixture keeps the properties of its parts. Its composition can vary, and its parts are separated by physical means. An ore's iron percentage changes from place to place, and sand can be removed physically. So the ore is a mixture. The iron oxide inside it is still a compound. Common slip: thinking 'more than one element' means mixture."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ compound تركيبه ثابت. إنما نسبة iron بتختلف وشوائب ممكن تتشال بطرق فيزيائية دي علامات على mixture."},"b":{"why":"الـ iron oxide نفسه فيه اتنين elements، ومع كده هو compound. فعدد الـ elements لوحده مابيفرّقش؛ اللي بيفرّق إن التركيب يختلف أو المكونات تتفصل بطرق فيزيائية.","feedback":"الفكرة الغلط: إن وجود أكتر من element في المادة بيخليها mixture."},"c":{"why":"الاتحاد الكيميائي بنسبة ثابتة ده وصف الـ compound، مش علامة على خلط فيزيائي.","feedback":"الفكرة الغلط: إن الاتحاد الكيميائي علامة على الـ mixture."},"d":{"why":"الـ compounds والـ mixtures الاتنين ممكن يبقوا مواد صلبة ليها لون، فالصفة دي مابتميّزش الـ mixture.","feedback":"الفكرة الغلط: إن الحالة أو اللون هما اللي بيحددوا إذا كانت المادة mixture ولا compound."}},"explanation":"الـ compound ليه نسبة ثابتة، فتركيبه مابيتغيرش أبدًا. أما الـ mixture فمكوناته بتفضل محتفظة بصفاتها، وتركيبه ممكن يختلف، ومكوناته بتتفصل بطرق فيزيائية. ونسبة الـ iron في الـ ore بتختلف من مكان للتاني، والرمل ممكن يتشال بطريقة فيزيائية. يبقى الـ ore ده mixture. لكن الـ iron oxide اللي جواه لسه compound. غلطة بتتكرر: إنك تفتكر إن وجود أكتر من element معناه إن المادة mixture."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":23,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.water-of-crystallization-1","kind":"question","version":1,"ord":367,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"chem.water-of-crystallization","concepts":[{"concept_id":"chem.water-of-crystallization","role":"primary"}],"title":"chem-s3-en.question-chem.water-of-crystallization-1","payload":{"stem":"Magnesium sulphate crystals have the formula $\\ce{MgSO4.7H2O}$. How many water molecules does the crystal hold for every one $\\ce{MgSO4}$?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"7","correct":true},{"id":"b","text":"14","correct":false},{"id":"c","text":"21","correct":false},{"id":"d","text":"1","correct":false}],"book_ref":"Prerequisite (1st secondary); used in Ch.1 iron ores table, p.16 (limonite, 2Fe2O3.3H2O)","difficulty":1,"concept_ids":["chem.water-of-crystallization"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right: the number in front of $\\ce{H2O}$ counts water molecules, so $\\ce{7H2O}$ means 7 water molecules for every one $\\ce{MgSO4}$."},"b":{"why":"You may have counted hydrogen atoms. The question asks for water molecules, and the 7 counts the molecules.","feedback":"Misconception: Counting hydrogen atoms instead of water molecules."},"c":{"why":"That counts atoms, not molecules. Each H2O is one molecule, and the 7 in front counts them.","feedback":"Misconception: Counting all the atoms in 7H2O."},"d":{"why":"The dot only joins the salt to its water. The number in front of H2O counts the water molecules.","feedback":"Misconception: The dot means one water molecule."}},"explanation":"In a hydrate formula, the dot joins the salt to its water of crystallization. The number in front of $\\ce{H2O}$ counts water molecules. So $\\ce{7H2O}$ means seven water molecules for every one $\\ce{MgSO4}$. Common slip: counting the 14 hydrogen atoms instead of the 7 molecules."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الرقم اللي قدام الـ $\\ce{H2O}$ بيعدّ الـ water molecules، يبقى $\\ce{7H2O}$ معناها 7 water molecules لكل $\\ce{MgSO4}$ واحد."},"b":{"why":"يمكن تكون عدّيت الـ hydrogen atoms، والسؤال عن الـ water molecules. الـ 7 دي بتعدّ الـ water molecules.","feedback":"الفكرة الغلط: إنك تعدّ الـ hydrogen atoms بدل الـ water molecules."},"c":{"why":"كده إنت بتعدّ atoms مش molecules. كل H2O ده molecule واحد، والـ 7 هي اللي بتعدّهم.","feedback":"الفكرة الغلط: إنك تعدّ كل الـ atoms اللي في 7H2O."},"d":{"why":"النقطة مجرد بتربط الـ salt بالميّة بتاعته. الرقم اللي واقف قدام الـ H2O هو اللي بيعدّ الـ molecules.","feedback":"الفكرة الغلط: إن النقطة معناها water molecule واحد."}},"explanation":"في صيغة الـ hydrate، النقطة بتربط الـ salt بالـ water of crystallization بتاعته. والرقم اللي قدام الـ $\\ce{H2O}$ هو اللي بيعدّ الـ water molecules. يبقى $\\ce{7H2O}$ معناها سبعة water molecules لكل $\\ce{MgSO4}$ واحد. غلطة بتتكرر: إنك تعدّ الـ 14 hydrogen atoms بدل الـ 7 molecules."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":24,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":47,"page_to":47,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.water-of-crystallization-2","kind":"question","version":1,"ord":368,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"chem.water-of-crystallization","concepts":[{"concept_id":"chem.water-of-crystallization","role":"primary"}],"title":"chem-s3-en.question-chem.water-of-crystallization-2","payload":{"stem":"Barium chloride crystals, $\\ce{BaCl2.2H2O}$, are heated strongly until all their water of crystallization is driven off. Which equation shows this change?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$\\ce{BaCl2.2H2O(s) ->[\\Delta] BaCl2(s) + 2H2O(v)}$","correct":true},{"id":"b","text":"$\\ce{BaCl2.2H2O(s) ->[\\Delta] BaCl2(s) + 2H2(g) + O2(g)}$","correct":false},{"id":"c","text":"$\\ce{BaCl2.2H2O(s) ->[\\Delta] BaCl2.H2O(s) + H2O(v)}$","correct":false},{"id":"d","text":"$\\ce{BaCl2.2H2O(s) ->[\\Delta] Ba(s) + Cl2(g) + 2H2O(v)}$","correct":false}],"book_ref":"Prerequisite (1st secondary); used in Ch.1 roasting of limonite, p.17","difficulty":2,"concept_ids":["chem.water-of-crystallization"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: heating drives off all the water of crystallization as vapour, $\\ce{2H2O(v)}$, and the salt itself stays as $\\ce{BaCl2}$."},"b":{"why":"Heating drives the water out of the crystal as vapour. It does not break the water molecules apart.","feedback":"Misconception: Heating splits the water of crystallization into hydrogen and oxygen."},"c":{"why":"The stem says all the water is driven off, but this product still holds water.","feedback":"Misconception: Only one water molecule leaves."},"d":{"why":"Losing water changes the crystal, but the salt $\\ce{BaCl2}$ itself does not break up here.","feedback":"Misconception: Driving off the water also breaks up the salt."}},"explanation":"Heating drives off water of crystallization as vapour. The salt itself stays as it is. Two water molecules leave for every $\\ce{BaCl2}$, so the equation shows $\\ce{2H2O(v)}$. The same thing happens when limonite is roasted. Common slip: splitting the water into $\\ce{H2}$ and $\\ce{O2}$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: التسخين بيطرد الـ water of crystallization كله على هيئة vapour، $\\ce{2H2O(v)}$، والـ salt نفسه بيفضل $\\ce{BaCl2}$ زي ما هو."},"b":{"why":"التسخين بيطرد الميّة برّه الـ crystal، لكن مش بيكسّر الـ water molecules نفسها.","feedback":"الفكرة الغلط: إن التسخين بيكسّر الـ water of crystallization لـ hydrogen و oxygen."},"c":{"why":"السؤال بيقول إن الميّة كلها اتطردت، والناتج ده لسه فيه ميّة.","feedback":"الفكرة الغلط: إن مفيش غير water molecule واحد بيخرج."},"d":{"why":"خروج الميّة بيغيّر الـ crystal، لكن الـ salt نفسه $\\ce{BaCl2}$ مش بيتكسّر هنا.","feedback":"الفكرة الغلط: إن طرد الميّة بيكسّر الـ salt كمان."}},"explanation":"التسخين بيطرد الـ water of crystallization على هيئة vapour، والـ salt نفسه بيفضل زي ما هو. بيخرج 2 water molecules لكل $\\ce{BaCl2}$، عشان كده المعادلة فيها $\\ce{2H2O(v)}$. ونفس الحكاية بتحصل لما الـ limonite بيحصله roasting. غلطة بتتكرر: إنك تكسّر الميّة لـ $\\ce{H2}$ و $\\ce{O2}$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":25,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":46,"page_to":47,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.mixture-separation-1","kind":"question","version":1,"ord":369,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"chem.mixture-separation","concepts":[{"concept_id":"chem.mixture-separation","role":"primary"}],"title":"chem-s3-en.question-chem.mixture-separation-1","payload":{"stem":"Magnetic separation can separate the two parts of a mixture when ...","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"one part is attracted by a magnet and the other part is not","correct":true},{"id":"b","text":"both parts are metals","correct":false},{"id":"c","text":"the two parts have different colours","correct":false},{"id":"d","text":"both parts are attracted by a magnet","correct":false}],"book_ref":"Prerequisite (preparatory science); used in Ch.1 'Firstly: Ore dressing', c- Concentrating processes, p.17","difficulty":1,"concept_ids":["chem.mixture-separation"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right: a magnet can pull out only the part it attracts, so the parts must differ in this property. The other part stays behind."},"b":{"why":"Not every metal is pulled by a magnet: a copper wire or an aluminum can is not attracted.","feedback":"Misconception: All metals are attracted by a magnet."},"c":{"why":"A magnet does not see colour. It acts only on whether a part is attracted by it.","feedback":"Misconception: Any visible difference lets a magnet sort the parts."},"d":{"why":"If the magnet pulls both parts, nothing stays behind, so the parts are not separated.","feedback":"Misconception: The more magnetic the parts, the better the separation."}},"explanation":"To separate a mixture, use a property its parts do not share. In magnetic separation, the magnet pulls the attracted part. The other part stays behind. No new substance forms. Common slip: thinking every metal is attracted by a magnet."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ magnet بيشد الجزء اللي بيتجذب له لوحده، فلازم الجزئين يختلفوا في الخاصية دي. والجزء التاني بيفضل مكانه."},"b":{"why":"مش كل metal الـ magnet بيشدّه، زي سلك الـ copper أو علبة الـ aluminum.","feedback":"الفكرة الغلط: إن كل الـ metals بتتجذب للـ magnet."},"c":{"why":"الـ magnet مش بيشوف الألوان؛ هو بيشد الحاجة اللي بتتجذب له، مهما كان لونها.","feedback":"الفكرة الغلط: إن أي فرق باين للعين يخلّي الـ magnet يفرز الأجزاء."},"d":{"why":"لو الـ magnet شدّ الجزئين، مفيش حاجة هتفضل ورا، فمفيش فصل.","feedback":"الفكرة الغلط: إن كل ما الأجزاء تبقى magnetic أكتر، الفصل يبقى أحسن."}},"explanation":"عشان تفصل mixture، استغل خاصية مش مشتركة بين أجزاؤه. في الـ magnetic separation، الـ magnet بيشد الجزء اللي بيتجذب، والجزء التاني بيفضل مكانه. ومفيش مادة جديدة بتتكوّن. غلطة بتتكرر: إنك تفتكر إن كل metal بيتجذب للـ magnet."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":26,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.mixture-separation-2","kind":"question","version":1,"ord":370,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"chem.mixture-separation","concepts":[{"concept_id":"chem.mixture-separation","role":"primary"}],"title":"chem-s3-en.question-chem.mixture-separation-2","payload":{"stem":"Iron filings are mixed with copper powder. The particles are about the same size. Which method separates them and keeps both metals unchanged?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Passing a magnet over the mixture","correct":true},{"id":"b","text":"Heating the mixture strongly in air","correct":false},{"id":"c","text":"Adding water, then filtering","correct":false},{"id":"d","text":"Shaking the mixture through a sieve","correct":false}],"book_ref":"Prerequisite (preparatory science); used in Ch.1 'Firstly: Ore dressing', c- Concentrating processes, p.17","difficulty":2,"concept_ids":["chem.mixture-separation"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Right: iron is attracted by a magnet and copper is not, so the magnet pulls out the iron. This is a physical method, so both metals stay unchanged."},"b":{"why":"Strong heating in air can make new substances, such as oxides, so the metals would not stay unchanged.","feedback":"Misconception: Heating separates the parts of a mixture."},"c":{"why":"Neither metal dissolves in water, so both would end up together on the filter paper.","feedback":"Misconception: Water and a filter separate any two solids."},"d":{"why":"A sieve sorts by size, and the particles here are about the same size. A different property must be used.","feedback":"Misconception: A sieve separates any two powders."}},"explanation":"Look for a property the two parts do not share. Iron is attracted by a magnet, and copper is not. So a magnet pulls out the iron and leaves the copper. This is a physical method: no new substance forms. Common slip: heating, which turns the metals into new substances."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ iron بيتجذب للـ magnet والـ copper لأ، فالـ magnet بيسحب الـ iron. ودي physical method، فالـ metals الاتنين بيفضلوا زي ما هما."},"b":{"why":"التسخين الشديد في الهوا ممكن يكوّن مواد جديدة، زي الـ oxides، فالـ metals مش هيفضلوا زي ما هما.","feedback":"الفكرة الغلط: إن التسخين بيفصل أجزاء الـ mixture."},"c":{"why":"ولا metal منهم بيدوب في الميّة، فالاتنين هيفضلوا مع بعض في الفلتر بعد الـ filtering.","feedback":"الفكرة الغلط: إن الميّة والفلتر بيفصلوا أي اتنين solids."},"d":{"why":"المنخل بيفرز على حسب الحجم، والحبيبات هنا تقريبًا في نفس الحجم، فلازم خاصية تانية مختلفة.","feedback":"الفكرة الغلط: إن المنخل بيفصل أي اتنين بودرة."}},"explanation":"دوّر على خاصية مش مشتركة بين الجزئين. الـ iron بيتجذب للـ magnet، والـ copper لأ. فالـ magnet بيسحب الـ iron ويسيب الـ copper. ودي physical method: مفيش مادة جديدة بتتكوّن. غلطة بتتكرر: إنك تختار التسخين، وهو بيحوّل الـ metals لمواد جديدة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":27,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.reaction-types-1","kind":"question","version":1,"ord":371,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"chem.reaction-types","concepts":[{"concept_id":"chem.reaction-types","role":"primary"}],"title":"chem-s3-en.question-chem.reaction-types-1","payload":{"stem":"Which of the following equations represents a thermal decomposition reaction?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"$\\ce{MgCO3(s) ->[\\Delta] MgO(s) + CO2(g)}$","correct":true},{"id":"b","text":"$\\ce{S(s) + O2(g) ->[\\Delta] SO2(g)}$","correct":false},{"id":"c","text":"$\\ce{Zn(s) + 2AgNO3(aq) -> Zn(NO3)2(aq) + 2Ag(s)}$","correct":false},{"id":"d","text":"$\\ce{KOH(aq) + HNO3(aq) -> KNO3(aq) + H2O(l)}$","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 roasting, p.17 (FeCO3 -> FeO + CO2)","difficulty":2,"concept_ids":["chem.reaction-types"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Right: one compound, $\\ce{MgCO3}$, breaks down by heat (Δ) into two simpler substances, MgO and $\\ce{CO2}$."},"b":{"why":"Heat is used here, but two substances are joining. No compound is breaking down.","feedback":"Misconception: Any reaction with heat (Δ) is a thermal decomposition."},"c":{"why":"There are two products, but there are also two reactants: one element takes another's place.","feedback":"Misconception: Two products always mean decomposition."},"d":{"why":"Two compounds go in and swap partners. Nothing is broken down by heat.","feedback":"Misconception: Forming water means something decomposed."}},"explanation":"Thermal decomposition breaks one compound into simpler substances by heat. Pattern: one compound in, two or more substances out, with Δ over the arrow. $\\ce{MgCO3}$ breaks into MgO and $\\ce{CO2}$. Sulphur burning is two substances joining. Zinc with silver nitrate is simple displacement. KOH with $\\ce{HNO3}$ is neutralization, a double displacement. Common slip: calling any heated reaction a decomposition."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: compound واحد، $\\ce{MgCO3}$، بيتكسّر بالحرارة (Δ) لمادتين أبسط، MgO و $\\ce{CO2}$."},"b":{"why":"هنا فيه حرارة فعلًا، لكن ده مادتين بيتحدوا مع بعض، مش compound واحد بيتكسّر.","feedback":"الفكرة الغلط: إن أي تفاعل فيه حرارة (Δ) يبقى thermal decomposition."},"c":{"why":"فيه ناتجين فعلًا، لكن فيه اتنين reactants، والـ zinc خد مكان الـ silver، يعني ده simple displacement.","feedback":"الفكرة الغلط: إن وجود ناتجين معناه دايمًا decomposition."},"d":{"why":"2 compounds بيدخلوا ويبدّلوا الشُّركا، ومفيش حاجة بتتكسّر بالحرارة.","feedback":"الفكرة الغلط: إن تكوين الميّة معناه إن فيه حاجة اتفككت."}},"explanation":"الـ thermal decomposition بيكسّر compound واحد لمواد أبسط بالحرارة. الشكل العام: compound واحد داخل، ومادتين أو أكتر خارجين، و Δ فوق السهم. الـ $\\ce{MgCO3}$ بيتكسّر لـ MgO و $\\ce{CO2}$. أما حرق الـ sulphur فده مادتين بيتحدوا مع بعض. والـ zinc مع الـ silver nitrate ده simple displacement. والـ KOH مع الـ $\\ce{HNO3}$ ده neutralization، وهو نوع من الـ double displacement. غلطة بتتكرر: إنك تسمّي أي تفاعل فيه تسخين decomposition."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":28,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-chem.reaction-types-2","kind":"question","version":1,"ord":372,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"chem.reaction-types","concepts":[{"concept_id":"chem.reaction-types","role":"primary"}],"title":"chem-s3-en.question-chem.reaction-types-2","payload":{"stem":"Lead(II) nitrate solution is added to potassium iodide solution: $\\ce{Pb(NO3)2(aq) + 2KI(aq) -> PbI2(s) v + 2KNO3(aq)}$. Which statement describes this reaction?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Double displacement; $\\ce{PbI2}$ is a precipitate","correct":true},{"id":"b","text":"Simple displacement; potassium takes the place of lead","correct":false},{"id":"c","text":"Double displacement; $\\ce{KNO3}$ is a precipitate","correct":false},{"id":"d","text":"Thermal decomposition, because a solid forms","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 iron oxides, pp.22-23 (precipitation)","difficulty":2,"concept_ids":["chem.reaction-types"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: two compounds exchange their partners, which is double displacement, and $\\ce{PbI2}$ carries (s) and ↓, so it is the precipitate."},"b":{"why":"There are two compounds on each side, and no lone element goes in or comes out.","feedback":"Misconception: Any swap of metals is a simple displacement."},"c":{"why":"$\\ce{KNO3}$ carries (aq): it stays dissolved. The precipitate is the product with the ↓ sign and the (s) symbol, $\\ce{PbI2}$.","feedback":"Misconception: Misreading which product is the precipitate."},"d":{"why":"There is no Δ over the arrow, and there are two reactants, not one.","feedback":"Misconception: A solid product means decomposition."}},"explanation":"Two compounds exchange their partners: AB + CD → AD + CB. That is double displacement. $\\ce{PbI2}$ does not dissolve, so it separates as a solid. The ↓ sign marks it as a precipitate. $\\ce{KNO3}$ stays dissolved (aq). Common slip: calling it simple displacement, but no free element takes part."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: 2 compounds بيبدّلوا الشُّركا، وده double displacement، والـ $\\ce{PbI2}$ عليه (s) و ↓، يبقى هو الـ precipitate."},"b":{"why":"فيه 2 compounds في كل ناحية، ومفيش element لوحده داخل أو خارج، فده مش simple displacement.","feedback":"الفكرة الغلط: إن أي تبديل بين metals يبقى simple displacement."},"c":{"why":"الـ $\\ce{KNO3}$ عليه الرمز (aq)، يعني بيفضل دايب. الناتج اللي عليه علامة ↓ والرمز (s) هو الـ $\\ce{PbI2}$.","feedback":"الفكرة الغلط: إنك تقرا غلط أنهي ناتج هو الـ precipitate."},"d":{"why":"مفيش Δ فوق السهم، والـ reactants اتنين مش واحد، فده مش thermal decomposition.","feedback":"الفكرة الغلط: إن وجود solid في النواتج معناه decomposition."}},"explanation":"2 compounds بيبدّلوا الشُّركا: AB + CD → AD + CB. وده اسمه double displacement. الـ $\\ce{PbI2}$ مابيدوبش، فبينفصل على هيئة solid، وعلامة ↓ بتقول إنه precipitate. أما الـ $\\ce{KNO3}$ فبيفضل دايب (aq). غلطة بتتكرر: إنك تسمّيه simple displacement، مع إن مفيش element حر داخل في التفاعل."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":29,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","relation":"beyond"}]},{"id":"chem-s3-en.question-stoich.molar-mass-1","kind":"question","version":1,"ord":373,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"stoich.molar-mass","concepts":[{"concept_id":"stoich.molar-mass","role":"primary"}],"title":"chem-s3-en.question-stoich.molar-mass-1","payload":{"stem":"Natural gas is mostly methane, $\\ce{CH4}$. What is the molar mass of methane? (C = 12, H = 1)","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"16 g/mol","correct":true},{"id":"b","text":"5 g/mol","correct":false},{"id":"c","text":"13 g/mol","correct":false},{"id":"d","text":"52 g/mol","correct":false}],"book_ref":"Prerequisite (1st secondary); molar mass in Ch.2 'Feed Back' p.30; used with Ch.1 p.18 (natural gas, 93% methane)","difficulty":1,"concept_ids":["stoich.molar-mass"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right: 1 × 12 + 4 × 1 = 16 g/mol."},"b":{"why":"That counts atoms (1 + 4). Molar mass adds the mass of each atom.","feedback":"Misconception: Counting atoms instead of adding their masses."},"c":{"why":"That adds one H, but the subscript 4 shows four H atoms.","feedback":"Misconception: Ignoring the subscript."},"d":{"why":"The 4 belongs to H only; 52 g/mol comes from multiplying the carbon by 4 too.","feedback":"Misconception: The subscript multiplies the whole formula."}},"explanation":"Molar mass is the sum of the atomic masses in the formula. Multiply each atomic mass by its number of atoms, then add. $\\ce{CH4}$: 1 × 12 + 4 × 1 = 16 g/mol. Common slip: 13 g/mol, from forgetting the subscript 4."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: 1 × 12 + 4 × 1 = 16 g/mol."},"b":{"why":"كده إنت عدّيت الذرات (1 + 4). الـ molar mass بتجمع كتلة كل ذرة.","feedback":"الفكرة الغلط: إنك تعدّ الذرات بدل ما تجمع كتلتها."},"c":{"why":"كده إنت جمعت H واحد، لكن الـ subscript 4 بيقول إن فيه 4 ذرات H.","feedback":"الفكرة الغلط: إنك تتجاهل الـ subscript."},"d":{"why":"الـ 4 تبع الـ H لوحده؛ كده إنت ضربت الـ carbon كمان.","feedback":"الفكرة الغلط: إن الـ subscript بيضرب في الـ formula كلها."}},"explanation":"الـ Molar mass هي مجموع الـ atomic masses اللي في الـ formula. اضرب الـ atomic mass بتاعة العنصر في عدد ذراته، وبعدين اجمع. الـ $\\ce{CH4}$: 1 × 12 + 4 × 1 = 16 g/mol. غلطة بتتكرر: 13 g/mol، ودي جاية من إنك نسيت الـ subscript 4."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":30,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-stoich.molar-mass-2","kind":"question","version":1,"ord":374,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"stoich.molar-mass","concepts":[{"concept_id":"stoich.molar-mass","role":"primary"}],"title":"chem-s3-en.question-stoich.molar-mass-2","payload":{"stem":"Green iron(II) sulphate crystals have the formula $\\ce{FeSO4.7H2O}$. Calculate their molar mass. (Fe = 56, S = 32, O = 16, H = 1)","tags":["diagnostic","prerequisite","calculation"],"type":"numeric","bloom":"apply","answer":{"unit":"g/mol","value":278,"tolerance":0.5},"book_ref":"Prerequisite (1st secondary); molar mass in Ch.2 'Feed Back' p.30; used with the iron ores table, Ch.1 p.16 (hydrated ore)","difficulty":3,"concept_ids":["stoich.molar-mass"],"est_seconds":90},"layer":{"explanation":"Work in two parts. $\\ce{FeSO4}$ = 56 + 32 + 4 × 16 = 152 g/mol. Each $\\ce{H2O}$ = 2 × 1 + 16 = 18. Seven of them = 7 × 18 = 126. Add the parts: 152 + 126 = 278 g/mol. The dot means: add the water's mass too. Likely wrong answers: 152 (water left out) or 170 (only one water counted)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"اشتغل على جزئين. الـ $\\ce{FeSO4}$ = 56 + 32 + 4 × 16 = 152 g/mol. والـ $\\ce{H2O}$ الواحد = 2 × 1 + 16 = 18، والسبعة = 7 × 18 = 126. اجمع الجزئين: 152 + 126 = 278 g/mol. النقطة معناها: ضيف كتلة المية كمان. إجابات غلط متوقعة: 152 (لو سبت المية برّه الحساب) أو 170 (لو مفيش غير $\\ce{H2O}$ واحد اتحسب)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":31,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-stoich.mass-percentage-1","kind":"question","version":1,"ord":375,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"stoich.mass-percentage","concepts":[{"concept_id":"stoich.mass-percentage","role":"primary"}],"title":"chem-s3-en.question-stoich.mass-percentage-1","payload":{"stem":"Which expression gives the mass percentage of iron in iron(II) oxide, $\\ce{FeO}$? (Fe = 56, O = 16)","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"$\\dfrac{56}{72} \\times 100$","correct":true},{"id":"b","text":"$\\dfrac{1}{2} \\times 100$","correct":false},{"id":"c","text":"$\\dfrac{16}{72} \\times 100$","correct":false},{"id":"d","text":"$\\dfrac{72}{56} \\times 100$","correct":false}],"book_ref":"Prerequisite (1st secondary); used with the iron % column of the ores table, Ch.1 p.16, and roasting, p.17","difficulty":2,"concept_ids":["stoich.mass-percentage"],"est_seconds":50},"layer":{"choices":{"a":{"why":"Right: the mass of iron in one mole (56 g) over the molar mass of $\\ce{FeO}$ (72 g/mol), times 100."},"b":{"why":"That divides atoms (1 out of 2). The formula uses masses: 56 g of iron in one mole.","feedback":"Misconception: Using numbers of atoms instead of masses."},"c":{"why":"16 is the mass of oxygen, but the question asks about iron.","feedback":"Misconception: Putting the wrong element's mass on top."},"d":{"why":"This gives more than 100%: the whole is on top instead of the part.","feedback":"Misconception: Inverting the fraction."}},"explanation":"% of an element = (mass of the element in one mole ÷ molar mass) × 100. Molar mass of FeO = 56 + 16 = 72 g/mol. One mole holds 56 g of iron. So % Fe = 56/72 × 100, about 77.8%. Common slip: 1/2 × 100, which counts atoms, not masses."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: كتلة الـ iron في الـ mole الواحد (56 g) على الـ molar mass بتاعة الـ $\\ce{FeO}$ (72 g/mol)، مضروبة في 100."},"b":{"why":"كده إنت قسمت ذرات (1 من 2). القانون بيستخدم الكتل: فيه 56 g iron في الـ mole الواحد.","feedback":"الفكرة الغلط: إنك تستخدم عدد الذرات بدل الكتل."},"c":{"why":"الـ 16 دي كتلة الـ oxygen، لكن السؤال بيسأل عن الـ iron.","feedback":"الفكرة الغلط: إنك تحط كتلة العنصر الغلط فوق في الكسر."},"d":{"why":"ده بيطلّع أكتر من 100%: الكل اتحط فوق بدل الجزء.","feedback":"الفكرة الغلط: إنك تقلب الكسر."}},"explanation":"النسبة المئوية لعنصر = (كتلة العنصر في الـ mole الواحد ÷ الـ molar mass) × 100. الـ molar mass بتاعة الـ FeO = 56 + 16 = 72 g/mol، والـ mole الواحد فيه 56 g من الـ iron. يبقى % Fe = 56/72 × 100، يعني حوالي 77.8%. غلطة بتتكرر: 1/2 × 100، ودي بتعدّ الذرات مش الكتل."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":32,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-stoich.mass-percentage-2","kind":"question","version":1,"ord":376,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"stoich.mass-percentage","concepts":[{"concept_id":"stoich.mass-percentage","role":"primary"}],"title":"chem-s3-en.question-stoich.mass-percentage-2","payload":{"stem":"Calculate the mass percentage of iron in iron(III) sulphate, $\\ce{Fe2(SO4)3}$. (Fe = 56, S = 32, O = 16)","tags":["diagnostic","prerequisite","calculation"],"type":"numeric","bloom":"apply","answer":{"unit":"%","value":28,"tolerance":0.5},"book_ref":"Prerequisite (1st secondary); used with the iron % column of the ores table, Ch.1 p.16","difficulty":3,"concept_ids":["stoich.mass-percentage"],"est_seconds":100},"layer":{"explanation":"Step 1, molar mass: one $\\ce{SO4}$ group = 32 + 4 × 16 = 96. Three groups = 288. Add 2 × 56 = 112. Total = 400 g/mol. Step 2, iron in one mole = 2 × 56 = 112 g. Step 3: % Fe = 112/400 × 100 = 28%. Likely wrong answers: 14% (one Fe only), or about 54% (the 3 after the bracket ignored)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الخطوة 1، الـ molar mass: مجموعة الـ $\\ce{SO4}$ الواحدة = 32 + 4 × 16 = 96، والتلات مجموعات = 288. ضيف عليهم 2 × 56 = 112. المجموع = 400 g/mol. الخطوة 2، الـ iron اللي في الـ mole الواحد = 2 × 56 = 112 g. الخطوة 3: % Fe = 112/400 × 100 = 28%. إجابات غلط متوقعة: 14% (لو مفيش غير Fe واحد اتحسب)، أو حوالي 54% (لو تجاهلت الـ 3 اللي بعد القوس)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":33,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.natural-gas-methane-1","kind":"question","version":2,"ord":377,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"chem.natural-gas-methane","concepts":[{"concept_id":"chem.natural-gas-methane","role":"primary"}],"title":"chem-s3-en.question-chem.natural-gas-methane-1","payload":{"stem":"Natural gas is used as a fuel in homes and in industry. What is its main component?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"Methane, $\\ce{CH4}$","correct":true},{"id":"b","text":"Carbon monoxide, $\\ce{CO}$","correct":false},{"id":"c","text":"Hydrogen, $\\ce{H2}$","correct":false},{"id":"d","text":"Carbon dioxide, $\\ce{CO2}$","correct":false}],"book_ref":"Prerequisite (preparatory science); used in Ch.1 'Secondly: Reduction of Iron Ores' (b), p.18 (natural gas, 93% methane)","difficulty":1,"concept_ids":["chem.natural-gas-methane"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Right: methane, $\\ce{CH4}$, is the main component of natural gas; the book gives 93% methane."},"b":{"why":"CO can be made from natural gas in industry, but it is not what comes out of the ground.","feedback":"Misconception: Natural gas is carbon monoxide."},"c":{"why":"Natural gas holds hydrogen atoms, but bonded to carbon in a compound, not as hydrogen gas.","feedback":"Misconception: Natural gas is hydrogen gas."},"d":{"why":"$\\ce{CO2}$ forms when a fuel burns, so it cannot be the fuel itself.","feedback":"Misconception: The gas made by burning is the fuel."}},"explanation":"Natural gas is a fuel found underground. Its main part is methane, $\\ce{CH4}$. The book gives 93% methane. In the Midrex furnace, natural gas is changed into the gases that reduce iron ore. Common slip: choosing CO, which is made from natural gas, not found as it."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ methane، $\\ce{CH4}$، هو المكوّن الأساسي للـ natural gas؛ والكتاب بيقول 93% methane."},"b":{"why":"الـ CO ممكن يتعمل من الـ natural gas في الصناعة، لكنه مش هو اللي بيطلع من الأرض.","feedback":"الفكرة الغلط: إن الـ natural gas هو carbon monoxide."},"c":{"why":"الـ natural gas فيه ذرات hydrogen، لكنها مرتبطة بالـ carbon في compound، مش hydrogen gas لوحده.","feedback":"الفكرة الغلط: إن الـ natural gas هو hydrogen gas."},"d":{"why":"الـ $\\ce{CO2}$ بيتكوّن لما الوقود يتحرق، فمينفعش يكون هو نفسه الوقود.","feedback":"الفكرة الغلط: إن الغاز اللي بيطلع من الاحتراق هو الوقود."}},"explanation":"الـ natural gas وقود موجود تحت الأرض، والمكوّن الأساسي فيه هو الـ methane، $\\ce{CH4}$. الكتاب بيقول إنه 93% methane. وفي الـ Midrex furnace، الـ natural gas بيتحوّل للغازات اللي بتعمل reduction للـ iron ore. غلطة بتتكرر: إنك تختار الـ CO، وده بيتعمل من الـ natural gas، مش هو اللي بيتلاقى تحت الأرض."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":34,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.natural-gas-methane-2","kind":"question","version":1,"ord":378,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"chem.natural-gas-methane","concepts":[{"concept_id":"chem.natural-gas-methane","role":"primary"}],"title":"chem-s3-en.question-chem.natural-gas-methane-2","payload":{"stem":"Methane, $\\ce{CH4}$, is called the simplest hydrocarbon. Why?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"It contains carbon and hydrogen only, and its molecule has only one carbon atom.","correct":true},{"id":"b","text":"It contains carbon, hydrogen and oxygen in the smallest amounts.","correct":false},{"id":"c","text":"Its molecule contains only one hydrogen atom.","correct":false},{"id":"d","text":"It is a gas at room temperature.","correct":false}],"book_ref":"Prerequisite (preparatory science); used in Ch.1 'Secondly: Reduction of Iron Ores' (b), p.18","difficulty":2,"concept_ids":["chem.natural-gas-methane"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: a hydrocarbon contains carbon and hydrogen only, and methane has the smallest possible number of carbon atoms: one."},"b":{"why":"Its formula, $\\ce{CH4}$, has no oxygen. A hydrocarbon contains carbon and hydrogen only.","feedback":"Misconception: Hydrocarbons contain oxygen."},"c":{"why":"The subscript 4 after H shows four hydrogen atoms, not one.","feedback":"Misconception: Misreading the subscript in CH4."},"d":{"why":"Being a gas is a physical property. 'Simplest' is about the atoms in the molecule.","feedback":"Misconception: A physical state decides how simple a compound is."}},"explanation":"A hydrocarbon is a compound of carbon and hydrogen only. Methane, $\\ce{CH4}$, has one carbon atom bonded to four hydrogen atoms. No hydrocarbon has fewer carbon atoms, so methane is the simplest. Common slip: misreading $\\ce{CH4}$ as having one hydrogen atom."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ hydrocarbon مفيهوش غير carbon و hydrogen، والـ methane فيه أقل عدد ممكن من ذرات الـ carbon: ذرة واحدة."},"b":{"why":"الـ formula بتاعته، $\\ce{CH4}$، مفيهاش أي oxygen، وكلمة 'hydrocarbon' معناها carbon و hydrogen بس.","feedback":"الفكرة الغلط: إن الـ Hydrocarbons فيها oxygen."},"c":{"why":"الـ subscript اللي بعد الـ H هو 4، يعني فيه أربع ذرات hydrogen، مش واحدة.","feedback":"الفكرة الغلط: إنك تقرا الـ subscript اللي في الـ CH4 غلط."},"d":{"why":"إنه يبقى غاز ده physical property. وكلمة 'simplest' هنا بتتكلم عن الذرات اللي في الـ molecule، مش الحالة.","feedback":"الفكرة الغلط: إن الـ physical state هي اللي بتحدد الـ compound بسيط قد إيه."}},"explanation":"الـ hydrocarbon هو compound مفيهوش غير carbon و hydrogen. والـ methane، $\\ce{CH4}$، فيه ذرة carbon واحدة مرتبطة بأربع ذرات hydrogen. مفيش hydrocarbon فيه ذرات carbon أقل من كده، وعشان كده الـ methane هو الأبسط. غلطة بتتكرر: إنك تقرا الـ $\\ce{CH4}$ كأن فيه ذرة hydrogen واحدة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":35,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-fe.occurrence-1","kind":"question","version":2,"ord":379,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.occurrence","concepts":[{"concept_id":"fe.occurrence","role":"primary"}],"title":"chem-s3-en.question-fe.occurrence-1","payload":{"stem":"Choose the correct statement about iron.","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"Only three elements are more abundant than iron in the earth's crust: oxygen, silicon and aluminum.","correct":true},{"id":"b","text":"Iron is the most abundant element in the earth's crust, because it is the most important metal in heavy industries.","correct":false,"misconception_id":"fe.occurrence.mc1"},{"id":"c","text":"The mass of iron in the earth decreases gradually as we come close to the earth's core.","correct":false},{"id":"d","text":"An iron ore is suitable for extraction of iron when its iron percentage is high, whatever its impurities.","correct":false,"misconception_id":"fe.occurrence.mc3"}],"book_ref":"Ch.1 'IRON', p.16; exam form: choose the correct statement","difficulty":2,"concept_ids":["fe.occurrence"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: iron is the fourth most abundant element in the earth's crust, after oxygen, silicon and aluminum."},"b":{"why":"'Most important' tells you how much we use iron, not how much of it the crust holds.","feedback":"Misconception: Iron is the most abundant element in the crust (importance = abundance)."},"c":{"why":"The trend is the other way: the mass of iron increases gradually as we come close to the earth's core.","feedback":"Misconception: The iron trend with depth is reversed."},"d":{"why":"Iron percentage is only one factor. The book also counts the impurities' composition and harmful elements, such as sulphur.","feedback":"Misconception: Only the iron percentage decides if an ore is suitable."}},"explanation":"Iron is the fourth most abundant element in the earth's crust, after oxygen, silicon and aluminum. It forms about 5% of the crust by mass. Its mass increases gradually as we come close to the earth's core. An ore's suitability depends on three factors. They are the iron percentage, the impurities' composition and harmful elements (S, P, As). Common slip: 'most important' read as 'most abundant'."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ iron هو رابع عنصر في الوفرة في القشرة الأرضية، بعد الـ oxygen والـ silicon والـ aluminum."},"b":{"why":"كلمة 'most important' بتقولك إحنا بنستخدم الـ iron قد إيه، مش القشرة الأرضية فيها منه قد إيه؛ هو رابع عنصر في الوفرة.","feedback":"الفكرة الغلط: إن الـ iron هو أكتر عنصر موجود في القشرة الأرضية (كأن الأهمية = الوفرة)."},"c":{"why":"الـ iron بيزيد تدريجيًا وإحنا بنقرب من لب الأرض، يعني اللب فيه iron أكتر من القشرة الأرضية.","feedback":"الفكرة الغلط: إن اتجاه الـ iron مع العمق معكوس."},"d":{"why":"نسبة الـ iron عامل واحد من التلات عوامل. الكتاب بيحسب كمان تركيب الشوائب والعناصر الضارة، زي الـ sulphur.","feedback":"الفكرة الغلط: إن نسبة الـ iron لوحدها هي اللي بتحدد إذا كان الـ ore مناسب."}},"explanation":"الـ iron هو رابع عنصر في الوفرة في القشرة الأرضية، بعد الـ oxygen والـ silicon والـ aluminum، وبيمثل حوالي 5% من القشرة الأرضية بالكتلة. وكتلته بتزيد تدريجيًا وإحنا بنقرب من لب الأرض. وصلاحية الـ ore بتعتمد على تلات عوامل: نسبة الـ iron، وتركيب الشوائب، والعناصر الضارة (S, P, As). غلطة بتتكرر: إنك تقرا 'most important' كأنها 'most abundant'."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":36,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron","section_title":"Iron","section_path":["Transition Elements","Iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.ores-1","kind":"question","version":1,"ord":380,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.ores","concepts":[{"concept_id":"fe.ores","role":"primary"}],"title":"chem-s3-en.question-fe.ores-1","payload":{"stem":"Match each ore in column (A) with its chemical formula and colour in column (B).","tags":["exam-style","match"],"type":"match","bloom":"remember","answer":[["l1","r1"],["l2","r2"],["l3","r3"],["l4","r4"]],"choices":[{"id":"l1","text":"Hematite"},{"id":"l2","text":"Limonite"},{"id":"l3","text":"Magnetite"},{"id":"l4","text":"Siderite"},{"id":"r1","text":"$\\ce{Fe2O3}$, blood red"},{"id":"r2","text":"$\\ce{2Fe2O3.3H2O}$, yellow"},{"id":"r3","text":"$\\ce{Fe3O4}$, black"},{"id":"r4","text":"$\\ce{FeCO3}$, yellowish grey"}],"book_ref":"Ch.1 'IRON', table of the most important iron ores, p.16; exam form: match columns","difficulty":2,"concept_ids":["fe.ores"],"est_seconds":60},"layer":{"choices":{"l1":{"why":"Hematite is iron (III) oxide, so it matches $\\ce{Fe2O3}$, blood red."},"l2":{"why":"Limonite is hydrated iron (III) oxide, so it matches $\\ce{2Fe2O3.3H2O}$, yellow."},"l3":{"why":"Magnetite is magnetic iron oxide, so it matches $\\ce{Fe3O4}$, black (the ore with magnetic properties)."},"l4":{"why":"Siderite is iron (II) carbonate, so it matches $\\ce{FeCO3}$, yellowish grey."},"r1":{"why":"$\\ce{Fe2O3}$ (iron (III) oxide) with a blood red colour is hematite."},"r2":{"why":"$\\ce{2Fe2O3.3H2O}$ is hydrated iron (III) oxide, the yellow ore: limonite."},"r3":{"why":"$\\ce{Fe3O4}$ is magnetic iron oxide, the black ore with magnetic properties: magnetite."},"r4":{"why":"$\\ce{FeCO3}$ is iron (II) carbonate, the yellowish grey ore: siderite."}},"explanation":"Hematite is iron (III) oxide, $\\ce{Fe2O3}$, blood red. Limonite is hydrated iron (III) oxide, $\\ce{2Fe2O3.3H2O}$, yellow. Magnetite is magnetic iron oxide, $\\ce{Fe3O4}$, black, with magnetic properties. Siderite is iron (II) carbonate, $\\ce{FeCO3}$, yellowish grey. Most common slip: swapping the formulas of hematite and magnetite. Another: matching yellow limonite with yellowish grey siderite."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"l1":{"why":"الـ Hematite هو iron (III) oxide، فبيتوصّل بـ $\\ce{Fe2O3}$، أحمر دموي."},"l2":{"why":"الـ Limonite هو hydrated iron (III) oxide، فبيتوصّل بـ $\\ce{2Fe2O3.3H2O}$، أصفر."},"l3":{"why":"الـ Magnetite هو magnetic iron oxide، فبيتوصّل بـ $\\ce{Fe3O4}$، أسود (الـ ore اللي عنده خواص مغناطيسية)."},"l4":{"why":"الـ Siderite هو iron (II) carbonate، فبيتوصّل بـ $\\ce{FeCO3}$، رمادي مصفرّ."},"r1":{"why":"الـ $\\ce{Fe2O3}$ (iron (III) oxide) اللي لونه أحمر دموي هو الـ hematite."},"r2":{"why":"الـ $\\ce{2Fe2O3.3H2O}$ هو hydrated iron (III) oxide، الـ ore الأصفر: الـ limonite."},"r3":{"why":"الـ $\\ce{Fe3O4}$ هو magnetic iron oxide، الـ ore الأسود اللي عنده خواص مغناطيسية: الـ magnetite."},"r4":{"why":"الـ $\\ce{FeCO3}$ هو iron (II) carbonate، الـ ore الرمادي المصفرّ: الـ siderite."}},"explanation":"الـ Hematite هو iron (III) oxide، يعني $\\ce{Fe2O3}$، ولونه أحمر دموي. الـ Limonite هو hydrated iron (III) oxide، يعني $\\ce{2Fe2O3.3H2O}$، ولونه أصفر. الـ Magnetite هو magnetic iron oxide، يعني $\\ce{Fe3O4}$، لونه أسود وعنده خواص مغناطيسية. الـ Siderite هو iron (II) carbonate، يعني $\\ce{FeCO3}$، ولونه رمادي مصفرّ. أشهر غلطة: إنك تبدّل الـ formula بتاعة الـ hematite مع بتاعة الـ magnetite. وغلطة تانية: إنك توصّل الـ limonite الأصفر بالرمادي المصفرّ بتاع الـ siderite."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":37,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.ore-dressing-1","kind":"question","version":1,"ord":381,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.ore-dressing","concepts":[{"concept_id":"fe.ore-dressing","role":"primary"}],"title":"chem-s3-en.question-fe.ore-dressing-1","payload":{"stem":"Arrange the following events in the order in which they happen as iron ore is prepared and used in the furnace.","tags":["exam-style","arrange"],"type":"order","bloom":"understand","answer":["e1","e2","e3","e4"],"choices":[{"id":"e1","text":"The ore is crushed into pieces of a suitable size."},{"id":"e2","text":"A huge amount of fine ore particles is obtained."},{"id":"e3","text":"The fine particles are collected into larger, homogeneous pieces (sintering)."},{"id":"e4","text":"The ore is reduced to iron in the furnace."}],"book_ref":"Ch.1 'Extraction of Iron from its Ores', Firstly: Ore dressing, 1- a, b, c, p.17; exam form: arrange","difficulty":2,"concept_ids":["fe.ore-dressing"],"est_seconds":60},"layer":{"choices":{"e1":{"why":"Crushing breaks the big rocks that leave the mine; the small pieces and fine particles come from it."},"e2":{"why":"Fine particles are a by-product of crushing, the process that breaks the ore."},"e3":{"why":"Sintering needs something to work on: it collects the fine particles into larger pieces."},"e4":{"why":"The furnace cannot use fine particles directly; they must first be collected into larger pieces by sintering."}},"explanation":"Crushing gives the ore a suitable size, so it is easily reduced. Crushing (and cleaning the furnace) also gives a huge amount of fine particles. These cannot be used directly in the furnace. Sintering collects them into larger pieces of similar size. Later, after roasting too, the ore goes to the furnace for reduction. Most likely wrong order: sintering placed before crushing, as if sintering made the fine particles."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"e1":{"why":"الحتت الصغيرة والحبيبات الناعمة دي جاية من تكسير الصخور الكبيرة اللي طالعة من المنجم، فالتكسير بيسبقها."},"e2":{"why":"الحبيبات الناعمة دي ناتج جانبي للـ crushing، فبتظهر بعد ما الـ ore يتكسّر."},"e3":{"why":"الـ sintering محتاج حاجة يشتغل عليها: بيلمّ الحبيبات الناعمة اللي الـ crushing طلّعها."},"e4":{"why":"الفرن ماينفعش ياخد الحبيبات الناعمة على طول؛ لازم تتلمّ الأول بالـ sintering في حتت أكبر."}},"explanation":"الـ crushing بيدي الـ ore حجم مناسب عشان الـ reduction يبقى سهل. لكن الـ crushing (ومعاه تنضيف الفرن) بيطلّع كمان كمية كبيرة جدًا من الحبيبات الناعمة، ودي ماينفعش تتستخدم في الفرن على طول. هنا ييجي دور الـ sintering: بيلمّها في حتت أكبر حجمها متقارب. وبعد كده، وبعد الـ roasting كمان، الـ ore يروح الفرن عشان الـ reduction. أشهر غلطة: إنك تحط الـ sintering قبل الـ crushing، كأن الـ sintering هو اللي بيعمل الحبيبات الناعمة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":38,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.roasting-1","kind":"question","version":1,"ord":382,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.roasting","concepts":[{"concept_id":"fe.roasting","role":"primary"}],"title":"chem-s3-en.question-fe.roasting-1","payload":{"stem":"Write the balanced equation for the thermal decomposition of siderite during roasting, with state symbols.","tags":["exam-style","write-the-equation","equation"],"type":"short","bloom":"remember","answer":"\\ce{FeCO3(s) ->[\\Delta] FeO(s) + CO2(g)}","book_ref":"Ch.1 'Extraction of Iron from its Ores', Firstly: Ore dressing, 2- Roasting, p.17; exam form: write the equation","difficulty":2,"concept_ids":["fe.roasting"],"est_seconds":60},"layer":{"explanation":"Siderite is iron (II) carbonate, $\\ce{FeCO3}$. Strong heating breaks it into iron (II) oxide and carbon dioxide gas. Heat (Δ) goes over the arrow. Balance: 1 Fe, 1 C and 3 O on each side. In air, the FeO is then oxidized: $\\ce{2FeO + 1/2O2 -> Fe2O3}$. Grader looks for: $\\ce{FeCO3}$ alone on the left, FeO and $\\ce{CO2}$ on the right, Δ. Most likely wrong answer: writing Fe as a product, as if roasting reduced the ore."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ siderite هو iron (II) carbonate، يعني $\\ce{FeCO3}$. التسخين الشديد بيكسّره لـ iron (II) oxide وغاز carbon dioxide. الحرارة (Δ) بتتكتب فوق السهم. وزّن: 1 Fe و1 C و3 O على الناحيتين. وبعد كده، في الهوا، الـ FeO بيحصله oxidation: $\\ce{2FeO + 1/2O2 -> Fe2O3}$. المصحح بيدوّر على: $\\ce{FeCO3}$ لوحده على الشمال، والـ FeO والـ $\\ce{CO2}$ على اليمين، والـ Δ. أشهر غلطة: إنك تكتب Fe كناتج، كأن الـ roasting بيعمل reduction للـ ore."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":39,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.blast-furnace-reduction-1","kind":"question","version":1,"ord":383,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.blast-furnace-reduction","concepts":[{"concept_id":"fe.blast-furnace-reduction","role":"primary"}],"title":"chem-s3-en.question-fe.blast-furnace-reduction-1","payload":{"stem":"Explain the role of coke in the blast furnace. Support your answer with equations.","tags":["exam-style","explain-the-role"],"type":"short","bloom":"understand","answer":"Key points: Coke is the source of carbon monoxide, the reducing agent. (1) $\\ce{C(s) + O2(g) ->[\\Delta] CO2(g)}$ (2) $\\ce{CO2(g) + C(s) ->[\\Delta] 2CO(g)}$ (3) Carbon monoxide reduces the ore: $\\ce{3CO(g) + Fe2O3(s) ->[\\text{higher than } 700\\,^{\\circ}C] 2Fe(s) + 3CO2(g)}$.","book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (a), p.18; Evaluation Q5.1, p.26","difficulty":2,"concept_ids":["fe.blast-furnace-reduction"],"est_seconds":120},"layer":{"explanation":"Coke is a form of carbon. It burns to carbon dioxide. The carbon dioxide meets more hot coke and becomes carbon monoxide. Carbon monoxide takes oxygen from iron (III) oxide at higher than 700 °C, giving iron. So coke's role: the source of carbon monoxide, the reducing agent. Grader looks for the three equations and the words 'reducing agent'. Most likely wrong answer: 'coke reduces the ore directly'. Solid carbon never meets $\\ce{Fe2O3}$ in the book's equations."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ coke ده شكل من أشكال الـ carbon. بيتحرق ويبقى carbon dioxide. والـ carbon dioxide ده بيقابل coke سخن تاني فيتحوّل لـ carbon monoxide. والـ carbon monoxide بقى هو اللي بياخد الـ oxygen من الـ iron (III) oxide عند أعلى من 700 °C، فيطلع الـ iron. يبقى دور الـ coke: إنه مصدر الـ carbon monoxide، اللي هو الـ reducing agent. المصحح بيدوّر على المعادلات التلاتة وعلى كلمة 'reducing agent'. أشهر غلطة: 'الـ coke بيختزل الـ ore على طول'. في معادلات الكتاب، الـ carbon الصلب عمره ما بيقابل الـ $\\ce{Fe2O3}$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":40,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q5","section_title":"Explain the role","section_path":["Transition Elements","Evaluation","Explain the role"],"exercise":"Question 5","question":"1","relation":"from_book"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.midrex-reduction-1","kind":"question","version":1,"ord":384,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.midrex-reduction","concepts":[{"concept_id":"fe.midrex-reduction","role":"primary"}],"title":"chem-s3-en.question-fe.midrex-reduction-1","payload":{"stem":"Explain the role of natural gas in the Midrex furnace. Support your answer with equations.","tags":["exam-style","explain-the-role"],"type":"short","bloom":"understand","answer":"Key points: Natural gas (93% methane) is the source of water gas, a mixture of carbon monoxide and hydrogen, which are the reducing agents. (1) $\\ce{2CH4(g) + CO2(g) + H2O(v) ->[\\Delta] 3CO(g) + 5H2(g)}$ (2) $\\ce{2Fe2O3(s) + 3CO(g) + 3H2(g) ->[\\Delta] 4Fe(s) + 3CO2(g) + 3H2O(v)}$.","book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (b), p.18; Evaluation Q5.2, p.26","difficulty":2,"concept_ids":["fe.midrex-reduction"],"est_seconds":120},"layer":{"explanation":"Natural gas is 93% methane. Methane reacts with carbon dioxide and water vapour to give water gas: carbon monoxide and hydrogen. Both gases take oxygen from iron (III) oxide, giving iron. So the role of natural gas: the source of the reducing mixture (water gas). Grader looks for: both equations, and 'CO and H2 are the reducing agents'. Most likely wrong answer: 'methane reduces the ore'. Methane never meets the ore in the book's equations."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ natural gas نسبة الـ methane فيه 93%. الـ methane بيتفاعل مع الـ carbon dioxide والـ water vapour ويدّي water gas، اللي هو carbon monoxide و hydrogen. الغازين دول الاتنين بياخدوا الـ oxygen من الـ iron (III) oxide، فيطلع iron. يبقى دور الـ natural gas: إنه مصدر الخليط المختزل (الـ water gas). المصحح بيدوّر على: المعادلتين الاتنين، وجملة إن 'CO and H2 are the reducing agents'. أشهر غلطة: إنك تكتب إن 'methane reduces the ore'. الـ methane عمره ما بيقابل الـ ore في معادلات الكتاب."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":41,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q5","section_title":"Explain the role","section_path":["Transition Elements","Evaluation","Explain the role"],"exercise":"Question 5","question":"2","relation":"from_book"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.steel-production-1","kind":"question","version":2,"ord":385,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.steel-production","concepts":[{"concept_id":"fe.steel-production","role":"primary"}],"title":"chem-s3-en.question-fe.steel-production-1","payload":{"stem":"The steel industry depends on two essential processes. What are they?","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"Removing impurities from the furnace iron, and adding some elements to it","correct":true},{"id":"b","text":"Reducing the iron ore by carbon monoxide, and removing impurities from the iron","correct":false},{"id":"c","text":"Removing every element other than iron, to give pure iron","correct":false,"misconception_id":"fe.steel-production.mc1"},{"id":"d","text":"Roasting the iron in air, and passing carbon monoxide over it","correct":false}],"book_ref":"Ch.1 'Thirdly: Iron Production' and 'Steel', p.18; exam form: choose","difficulty":2,"concept_ids":["fe.steel-production"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right: these are the book's two essential processes: removal of impurities from the iron of the furnaces, and addition of some elements to give the properties industry needs."},"b":{"why":"Reduction happens in the blast furnace or Midrex furnace, before steel making. Steel making works on the iron once it exists.","feedback":"Misconception: Steel making includes reducing the ore; steel comes from the reduction furnace."},"c":{"why":"Pure iron would not have the special properties industry needs; steel making also puts some elements into the iron.","feedback":"Misconception: Steel is pure iron."},"d":{"why":"Roasting and reduction work on the ore, before there is any iron. Steel making works on the iron afterwards.","feedback":"Misconception: Steel making repeats the ore-dressing and reduction stages."}},"explanation":"After reduction comes the third stage: iron production, such as cast iron and steel. Steel making rests on two processes. First, removal of impurities from the iron that comes out of the furnaces. Second, addition of some elements to give the properties needed for industry. Common slip: thinking steel is pure iron. Elements such as carbon are added on purpose."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: دول العمليتين الأساسيتين في الكتاب: شيل الشوائب من الـ iron اللي طالع من الأفران، وإضافة بعض العناصر عشان تدّيله الخواص اللي الصناعة محتاجاها."},"b":{"why":"الـ reduction بيحصل في الـ blast furnace أو الـ Midrex furnace، قبل صناعة الـ steel؛ الـ steel بيتعمل من الـ iron بعد ما يبقى موجود.","feedback":"الفكرة الغلط: إن صناعة الـ steel فيها reduction للـ ore، وإن الـ steel بيطلع من فرن الـ reduction."},"c":{"why":"الـ iron النقي مافيهوش الخواص الخاصة اللي الصناعة محتاجاها، وصناعة الـ steel بتضيف عناصر للـ iron بقصد.","feedback":"الفكرة الغلط: إن الـ steel هو iron نقي."},"d":{"why":"الـ roasting والـ reduction بيشتغلوا على الـ ore، قبل ما يكون فيه iron أصلًا؛ صناعة الـ steel بتشتغل على الـ iron بعد كده.","feedback":"الفكرة الغلط: إن صناعة الـ steel بتعيد مراحل الـ ore-dressing والـ reduction."}},"explanation":"بعد الـ reduction بتيجي المرحلة التالتة: إنتاج الـ iron بأنواعه، زي الـ cast iron والـ steel. وصناعة الـ steel قايمة على عمليتين: الأولى، شيل الشوائب من الـ iron اللي طالع من الأفران. والتانية، إضافة بعض العناصر عشان تديله الخواص اللي الصناعة محتاجاها. غلطة بتتكرر: إنك تفتكر إن الـ steel هو iron نقي. عناصر زي الـ carbon بتتضاف بقصد."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":42,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.production","section_title":"Iron Production (steel)","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Iron Production (steel)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.occurrence-2","kind":"question","version":2,"ord":386,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.occurrence","concepts":[{"concept_id":"fe.occurrence","role":"primary"}],"title":"chem-s3-en.question-fe.occurrence-2","payload":{"stem":"A scientist finds a piece of metal that is about 90% pure iron. According to the book, where does iron in this form come from?","tags":["choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"A meteorite that fell from space","correct":true},{"id":"b","text":"A hematite deposit in the Oasis area","correct":false,"misconception_id":"fe.occurrence.mc2"},{"id":"c","text":"Rock dug from deep in the crust, close to the core","correct":false},{"id":"d","text":"A magnetite deposit, because magnetite is attracted by a magnet","correct":false}],"book_ref":"Ch.1 'IRON', p.16","difficulty":2,"concept_ids":["fe.occurrence"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: the book says iron is found as nearly pure metal (90%) in meteorites; in the earth's crust it is found in natural ores."},"b":{"why":"In the earth's crust, iron is found as iron compounds (mostly oxides) mixed with impurities, not as free metal.","feedback":"Misconception: Iron is mined as pure metal from its ores."},"c":{"why":"More iron near the core does not change how the crust holds it: crustal iron is found as compounds, mostly oxides, in ores.","feedback":"Misconception: More iron toward the core means free iron metal deep in the crust."},"d":{"why":"Magnetite has magnetic properties, but its name says magnetic iron oxide: an oxide, not pure iron.","feedback":"Misconception: A magnetic ore must be iron metal."}},"explanation":"In the earth's crust, iron is found as natural ores. These contain different iron compounds (mostly oxides) mixed with impurities. Iron is found as nearly pure metal (90%) only in meteorites. So a 90% iron lump points to a meteorite. Common slip: thinking magnetite, being magnetic, is iron metal. It is an iron oxide."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الكتاب بيقول إن الـ iron بيتلاقى كـ metal شبه نقي (90%) في الـ meteorites؛ أما في القشرة الأرضية فبيتلاقى في ores طبيعية."},"b":{"why":"الـ iron في القشرة الأرضية بيتلاقى على هيئة iron compounds (أغلبها oxides) مخلوطة بشوائب، مش metal حر.","feedback":"الفكرة الغلط: إن الـ iron بيتطلّع من الـ ores بتاعته على هيئة metal نقي."},"c":{"why":"إن الـ iron بيزيد قرب لب الأرض ده مش بيغيّر الشكل اللي القشرة الأرضية شايلاه بيه: iron compounds (أغلبها oxides) مخلوطة بشوائب.","feedback":"الفكرة الغلط: إن الـ iron الأكتر ناحية لب الأرض معناه إن فيه iron metal حر في عمق القشرة الأرضية."},"d":{"why":"الـ magnetite عنده magnetic properties، لكن اسمه magnetic iron oxide: يعني oxide، مش iron نقي.","feedback":"الفكرة الغلط: إن أي ore مغناطيسي لازم يكون iron metal."}},"explanation":"في القشرة الأرضية، الـ iron بيتلاقى على هيئة ores طبيعية، فيها iron compounds (أغلبها oxides) مخلوطة بشوائب. والـ iron بيتلاقى كـ metal شبه نقي (90%) في الـ meteorites تحديدًا. عشان كده حتة فيها 90% iron بتشاور على meteorite. غلطة بتتكرر: إنك تفتكر إن الـ magnetite، عشان هو مغناطيسي، يبقى iron metal. لأ، ده iron oxide."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":43,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron","section_title":"Iron","section_path":["Transition Elements","Iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.ores-2","kind":"question","version":1,"ord":387,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.ores","concepts":[{"concept_id":"fe.ores","role":"primary"}],"title":"chem-s3-en.question-fe.ores-2","payload":{"stem":"Three ore samples, each of mass 100 kg, were analysed (see the table). The impurities in them contain no iron. Which sample has the highest percentage of iron? (Fe = 56, C = 12, O = 16)","tags":["exam-style","two-step","calculation","data"],"type":"mcq","bloom":"analyze","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["X","Hematite","75% $\\ce{Fe2O3}$"],["Y","Magnetite","70% $\\ce{Fe3O4}$"],["Z","Siderite","85% $\\ce{FeCO3}$"]],"caption":"Made-up analysis data","headers":["Sample","Ore","Iron compound in the sample (by mass)"]},"children":[]}}},"choices":[{"id":"a","text":"Sample X","correct":true},{"id":"b","text":"Sample Y","correct":false},{"id":"c","text":"Sample Z","correct":false},{"id":"d","text":"The three samples are equal, because each has a mass of 100 kg","correct":false}],"book_ref":"Ch.1 'IRON', table of the most important iron ores, p.16; exam form: calculation from given data","difficulty":5,"concept_ids":["fe.ores"],"est_seconds":200},"layer":{"choices":{"a":{"why":"Right: X holds 75% of 70% = 52.5% iron, more than Y (50.7%) and Z (41.0%)."},"b":{"why":"Pure $\\ce{Fe3O4}$ is very rich in iron, but sample Y is only 70% $\\ce{Fe3O4}$. Combining both percentages gives about 50.7% iron.","feedback":"Misconception: The ore whose pure compound is richest in iron always gives the richest sample."},"c":{"why":"Z holds the most iron compound, but only 48.3% of $\\ce{FeCO3}$ is iron, so Z holds about 41% iron.","feedback":"Misconception: The highest share of iron compound means the highest share of iron."},"d":{"why":"Equal masses of ore can hold different masses of iron: the formulas and the percentages give each sample a different iron share.","feedback":"Misconception: Equal masses of ore hold equal masses of iron."}},"explanation":"Step 1, % Fe in each pure compound. $\\ce{Fe2O3}$: 112/160 × 100 = 70%. $\\ce{Fe3O4}$: 168/232 × 100 = 72.4%. $\\ce{FeCO3}$: 56/116 × 100 = 48.3%. Step 2, iron in each 100 kg sample. X: 75% of 70% = 52.5%. Y: 70% of 72.4% = 50.7%. Z: 85% of 48.3% = 41.0%. So X is richest, even though pure magnetite is richer than pure hematite. Likely wrong answers: Y (only the pure compound compared) or Z (only the compound share compared)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: العينة X فيها 75% من 70% = 52.5% iron، وده أكتر من Y (50.7%) و Z (41.0%)."},"b":{"why":"الـ $\\ce{Fe3O4}$ النقي فيه iron كتير فعلًا، لكن العينة Y فيها 70% $\\ce{Fe3O4}$ بس، فنسبة الـ iron فيها لازم تتحسب من النسبتين مع بعض.","feedback":"الفكرة الغلط: إن الـ ore اللي الـ compound النقي بتاعه فيه iron أكتر، هيدّي العينة اللي فيها iron أكتر على طول."},"c":{"why":"العينة Z فيها أكبر نسبة iron compound، لكن الـ iron نفسه حوالي 48% بس من الـ $\\ce{FeCO3}$، فالعينة كلها فيها iron أقل.","feedback":"الفكرة الغلط: إن أعلى نسبة من الـ iron compound معناها أعلى نسبة iron."},"d":{"why":"كتل متساوية من الـ ore ممكن يبقى فيها كتل مختلفة من الـ iron، لأن نسبة الـ compound ونسبة الـ Fe في الـ formula بيختلفوا من عينة للتانية.","feedback":"الفكرة الغلط: إن الكتل المتساوية من الـ ore فيها كتل متساوية من الـ iron."}},"explanation":"الخطوة 1: نسبة الـ Fe في كل compound نقي. $\\ce{Fe2O3}$: 112/160 × 100 = 70%. $\\ce{Fe3O4}$: 168/232 × 100 = 72.4%. $\\ce{FeCO3}$: 56/116 × 100 = 48.3%. الخطوة 2: الـ iron في كل عينة 100 kg. X: 75% من 70% = 52.5%. Y: 70% من 72.4% = 50.7%. Z: 85% من 48.3% = 41.0%. يعني X هي الأغنى، مع إن الـ magnetite النقي أغنى من الـ hematite النقي. الإجابات الغلط المتوقعة: Y (لو قارنت الـ compound النقي لوحده) أو Z (لو قارنت نسبة الـ compound لوحدها)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":44,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.ore-dressing-2","kind":"question","version":1,"ord":388,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.ore-dressing","concepts":[{"concept_id":"fe.ore-dressing","role":"primary"}],"title":"chem-s3-en.question-fe.ore-dressing-2","payload":{"stem":"Give reasons: Sintering processes are carried out on iron ore after crushing.","tags":["exam-style","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) Crushing (and cleaning the furnace) gives a huge amount of fine ore particles. (2) These fine particles cannot be used directly in the furnace. (3) Sintering collects them into larger pieces of similar size (homogeneous), so they can be used.","book_ref":"Ch.1 'Extraction of Iron from its Ores', Firstly: Ore dressing, 1- a, b, c, p.17 (b- Sintering processes); exam form: give reasons","difficulty":3,"concept_ids":["fe.ore-dressing"],"est_seconds":90},"layer":{"explanation":"Crushing gives pieces of a suitable size. But it also makes a huge amount of fine particles. The furnace cannot use these fine particles directly. Sintering gathers them into larger pieces that are similar and homogeneous. A full answer names the fine particles, says they cannot be used directly, and says sintering collects them. Most likely wrong answer: 'sintering melts the ore' or 'sintering removes impurities'. Removing impurities is the job of concentrating."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ crushing بيدينا حتت حجمها مناسب، لكنه كمان بيعمل كمية كبيرة جدًا من الحبيبات الناعمة. والفرن مايقدرش يستخدم الحبيبات الناعمة دي على طول. الـ sintering بيلمّها في حتت أكبر متشابهة ومتجانسة (homogeneous). الإجابة الكاملة لازم تذكر الحبيبات الناعمة، وتقول إنها ماينفعش تتستخدم على طول، وإن الـ sintering هو اللي بيجمّعها. أشهر غلطة: إنك تقول إن الـ sintering بيصهر الـ ore، أو إنه بيشيل الشوائب. شيل الشوائب ده شغل الـ concentrating."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":45,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.roasting-2","kind":"question","version":1,"ord":389,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.roasting","concepts":[{"concept_id":"fe.roasting","role":"primary"}],"title":"chem-s3-en.question-fe.roasting-2","payload":{"stem":"Explain the role of roasting in the extraction of iron. Support each purpose with one equation.","tags":["exam-style","explain-the-role"],"type":"short","bloom":"understand","answer":"Key points: Roasting = heating the ore strongly in air. Purpose (a): drying the ore and expelling humidity, to increase the percentage of iron, e.g. $\\ce{2Fe2O3.3H2O(s) ->[\\Delta] 2Fe2O3(s) + 3H2O(v)}$ (or $\\ce{FeCO3 ->[\\Delta] FeO + CO2}$). Purpose (b): oxidation of some impurities such as sulphur and phosphorus, e.g. $\\ce{S + O2 ->[\\Delta] SO2}$ or $\\ce{4P + 5O2 ->[\\Delta] 2P2O5}$.","book_ref":"Ch.1 'Extraction of Iron from its Ores', Firstly: Ore dressing, 2- Roasting, p.17; exam form: explain the role of","difficulty":3,"concept_ids":["fe.roasting"],"est_seconds":120},"layer":{"explanation":"Roasting improves the chemical properties of the ore. The ore is strongly heated in air. It has two purposes. First, it dries the ore and expels humidity, which increases the iron percentage. Second, it oxidizes impurities such as sulphur and phosphorus. Any book equation for each purpose earns the mark. Most likely wrong answer: 'roasting reduces the ore to iron'. Reduction comes later, in the blast furnace or Midrex furnace."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ roasting بيحسّن الخواص الكيميائية للـ ore: بنسخّن الـ ore تسخين شديد في الهوا. وليه هدفين. الأول: إنه يجفف الـ ore ويطرد الرطوبة، وده بيزوّد نسبة الـ iron. التاني: إنه يعمل oxidation لشوائب زي الـ sulphur والـ phosphorus. أي معادلة من الكتاب لكل هدف بتاخد الدرجة. أشهر غلطة: إنك تقول 'الـ roasting بيعمل reduction للـ ore لحد ما يبقى iron'. الـ reduction بييجي بعدين، في الـ blast furnace أو الـ Midrex furnace."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":46,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.blast-furnace-reduction-2","kind":"question","version":1,"ord":390,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.blast-furnace-reduction","concepts":[{"concept_id":"fe.blast-furnace-reduction","role":"primary"}],"title":"chem-s3-en.question-fe.blast-furnace-reduction-2","payload":{"stem":"The diagram shows the reactions in the blast furnace. Identify gases A and B, then write the balanced equation of each of the three steps.","tags":["exam-style","diagram","write-the-equation"],"type":"short","bloom":"analyze","answer":"Key points: A = carbon dioxide, $\\ce{CO2}$; B = carbon monoxide, CO. (1) $\\ce{C(s) + O2(g) ->[\\Delta] CO2(g)}$ (2) $\\ce{CO2(g) + C(s) ->[\\Delta] 2CO(g)}$ (3) $\\ce{3CO(g) + Fe2O3(s) ->[\\text{higher than } 700\\,^{\\circ}C] 2Fe(s) + 3CO2(g)}$.","figure":{"root":"f","elements":{"f":{"type":"FlowDiagram","props":{"edges":[{"to":"a","from":"c","label":"(1) + $\\ce{O2}$, heat"},{"to":"b","from":"a","label":"(2) + hot coke"},{"to":"fe","from":"b","label":"(3) + $\\ce{Fe2O3}$, higher than 700 °C"}],"nodes":[{"id":"c","label":"Coke, C"},{"id":"a","label":"Gas A"},{"id":"b","label":"Gas B"},{"id":"fe","label":"Fe + gas A"}],"layout":"horizontal","caption":"Reduction of iron ore in the blast furnace"},"children":[]}}},"book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (a), p.18; exam form: write equations from a diagram","difficulty":4,"concept_ids":["fe.blast-furnace-reduction"],"est_seconds":150},"layer":{"explanation":"Read the clues. Gas A forms when coke burns in oxygen, so A is $\\ce{CO2}$. Step (3) gives A back, which fits: CO becomes $\\ce{CO2}$ when it takes oxygen. Gas A plus hot coke gives B, which reduces the ore. So B is CO. Balance step (3): each CO takes one O atom, and $\\ce{Fe2O3}$ has three. So 3CO give 2Fe and $\\ce{3CO2}$. Most likely wrong answer: swapping A and B, which makes $\\ce{CO2}$ the reducing agent."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"اقرا الدلايل. الغاز A بيتكوّن لما الـ coke يتحرق في الـ oxygen، يبقى A هو $\\ce{CO2}$. والخطوة (3) بترجّع A تاني، وده منطقي: الـ CO بيبقى $\\ce{CO2}$ لما ياخد oxygen. والغاز A مع الـ coke السخن بيدّي B، والغاز B ده هو اللي بيختزل الـ ore. يبقى B هو CO. وازن الخطوة (3): كل CO بياخد ذرة O واحدة، والـ $\\ce{Fe2O3}$ فيه تلاتة. يبقى 3CO بيدّوا 2Fe و $\\ce{3CO2}$. أشهر غلطة: إنك تبدّل A مع B، وكده تخلّي الـ $\\ce{CO2}$ هو الـ reducing agent."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":47,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.midrex-reduction-2","kind":"question","version":1,"ord":391,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.midrex-reduction","concepts":[{"concept_id":"fe.midrex-reduction","role":"primary"}],"title":"chem-s3-en.question-fe.midrex-reduction-2","payload":{"stem":"In the Midrex furnace, natural gas is changed into water gas. Complete and balance the equation: $\\ce{2CH4(g) + CO2(g) + H2O(v) ->[\\Delta]}$ ...","tags":["exam-style","write-the-equation","balance","equation"],"type":"short","bloom":"apply","answer":"\\ce{2CH4(g) + CO2(g) + H2O(v) ->[\\Delta] 3CO(g) + 5H2(g)}","book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (b), p.18; exam form: complete and balance","difficulty":3,"concept_ids":["fe.midrex-reduction"],"est_seconds":90},"layer":{"explanation":"Water gas is a mixture of carbon monoxide and hydrogen. Count atoms on the left. C: 2 + 1 = 3, so 3CO. O: 2 + 1 = 3, and 3CO hold exactly 3 O. H: 8 + 2 = 10, so $\\ce{5H2}$. Grader looks for: CO and $\\ce{H2}$ as products, coefficients 3 and 5. Most likely wrong answer: writing $\\ce{CO2}$ or $\\ce{H2O}$ among the products, which are the products of the reduction step."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ water gas ده خليط من carbon monoxide و hydrogen. عدّ الذرات اللي على الشمال. الـ C: 2 + 1 = 3، يبقى 3CO. الـ O: 2 + 1 = 3، والـ 3CO فيهم 3 O بالظبط. الـ H: 8 + 2 = 10، يبقى $\\ce{5H2}$. المصحح بيدوّر على: الـ CO والـ $\\ce{H2}$ كـ products، والمعاملات 3 و5. أشهر غلطة: إنك تكتب $\\ce{CO2}$ أو $\\ce{H2O}$ في الـ products، ودول الـ products بتاعة خطوة الـ reduction."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":48,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.steel-production-2","kind":"question","version":2,"ord":392,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.steel-production","concepts":[{"concept_id":"fe.steel-production","role":"primary"}],"title":"chem-s3-en.question-fe.steel-production-2","payload":{"stem":"Which of the following statements about steel production are correct? Choose all that apply.","tags":["correct-statements","multi"],"type":"multi","bloom":"understand","choices":[{"id":"s1","text":"Steel can be produced in an electric furnace.","correct":true},{"id":"s2","text":"Impurities are removed from the iron that comes out of the blast furnace or the Midrex furnace.","correct":true},{"id":"s3","text":"Some elements are added to iron to give steel the properties needed by industry.","correct":true},{"id":"s4","text":"Steel comes directly out of the Midrex furnace.","correct":false},{"id":"s5","text":"Steel is iron from which every other element has been removed.","correct":false,"misconception_id":"fe.steel-production.mc1"},{"id":"s6","text":"The blast furnace is one of the three furnaces used to produce steel.","correct":false,"misconception_id":"fe.steel-production.mc2"}],"book_ref":"Ch.1 'Thirdly: Iron Production' and 'Steel', p.18","difficulty":3,"concept_ids":["fe.steel-production"],"est_seconds":75},"layer":{"choices":{"s1":{"why":"Right: the electric furnace is one of the three furnaces the book names for producing steel."},"s2":{"why":"Right: this is the first essential process of steel making."},"s3":{"why":"Right: this is the second essential process of steel making."},"s4":{"why":"The Midrex furnace produces iron from the ore; steel is made from that iron afterwards.","feedback":"Misconception: Steel comes straight out of the reduction furnace."},"s5":{"why":"Removing impurities is only one step; steel making also adds some elements to the iron.","feedback":"Misconception: Steel is pure iron."},"s6":{"why":"The blast furnace starts from ore and gives iron. The book's three steel furnaces are the oxygen converters, the open-hearth furnace and the electric furnace.","feedback":"Misconception: The blast furnace produces steel."}},"explanation":"The blast furnace and the Midrex furnace reduce the ore to iron. Steel is made from that iron later. Steel making removes impurities from the furnace iron and adds some elements. Steel is produced in one of three furnaces: the oxygen converters, the open-hearth furnace or the electric furnace. Common slips: 'steel is pure iron', and counting the blast furnace as a steel furnace."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"s1":{"why":"صح: الـ electric furnace واحد من الأفران التلاتة اللي الكتاب بيذكرها لإنتاج الـ steel."},"s2":{"why":"صح: دي أول عملية أساسية في صناعة الـ steel."},"s3":{"why":"صح: دي العملية الأساسية التانية في صناعة الـ steel."},"s4":{"why":"الـ Midrex furnace بيطلّع iron من الـ ore، والـ iron ده بيتعمل منه steel بعد كده في فرن تاني.","feedback":"الفكرة الغلط: إن الـ steel بيطلع على طول من الـ reduction furnace."},"s5":{"why":"شيل الـ impurities ده خطوة واحدة بس؛ صناعة الـ steel كمان بتضيف elements معيّنة للـ iron، فالـ steel مش pure iron.","feedback":"الفكرة الغلط: إن الـ steel هو pure iron."},"s6":{"why":"الـ blast furnace بيبدأ من الـ ore وبيطلّع iron؛ الأفران التلاتة اللي الكتاب بيسميها للـ steel هي الـ oxygen converters والـ open-hearth furnace والـ electric furnace.","feedback":"الفكرة الغلط: إن الـ blast furnace بيطلّع steel."}},"explanation":"الـ blast furnace والـ Midrex furnace بيعملوا reduce للـ ore لحد ما يبقى iron. وبعد كده الـ steel بيتصنع من الـ iron ده. صناعة الـ steel بتشيل الـ impurities من الـ iron اللي طالع من الـ furnace، وبتضيف له elements معيّنة. والـ steel بيتصنع في واحد من تلات أفران: الـ oxygen converters، أو الـ open-hearth furnace، أو الـ electric furnace. غلطات بتتكرر: إنك تقول إن الـ steel هو pure iron، أو تعدّ الـ blast furnace من أفران الـ steel."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":49,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.production","section_title":"Iron Production (steel)","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Iron Production (steel)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.occurrence-3","kind":"question","version":2,"ord":393,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.occurrence","concepts":[{"concept_id":"fe.occurrence","role":"primary"},{"concept_id":"fe.ores","role":"secondary"}],"title":"chem-s3-en.question-fe.occurrence-3","payload":{"stem":"A blood-red iron ore is mined in the Oasis area (Western Desert). A sample of it contains 80% by mass of the ore's iron compound. The rest is impurities that contain no iron. Calculate the percentage of iron in the sample. (Fe = 56, O = 16)","tags":["exam-style","two-step","calculation"],"type":"numeric","bloom":"apply","answer":{"unit":"%","value":56,"tolerance":0.5},"book_ref":"Ch.1 'IRON', p.16 (ores = iron compounds (mostly oxides) mixed with impurities) and iron ores table, p.16; exam form: two-step calculation","difficulty":4,"concept_ids":["fe.occurrence","fe.ores"],"est_seconds":150},"layer":{"explanation":"Step 1: a blood-red ore from the Oasis area is hematite, iron (III) oxide, $\\ce{Fe2O3}$. Step 2: % Fe in pure $\\ce{Fe2O3}$ = (2 × 56) / 160 × 100 = 70%. Step 3: only 80% of the sample is $\\ce{Fe2O3}$. So % Fe in the sample = 80/100 × 70 = 56%. This fits the book's range for hematite, 50-60%. The impurities add mass but no iron. Likely wrong answers: 70% (impurities forgotten) or 80% (the compound's share taken as iron's share)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الخطوة 1: ore لونه أحمر زي الدم من منطقة الواحات يبقى الـ hematite، يعني iron (III) oxide، $\\ce{Fe2O3}$. الخطوة 2: نسبة الـ Fe في الـ $\\ce{Fe2O3}$ النقي = (2 × 56) / 160 × 100 = 70%. الخطوة 3: العينة مش كلها $\\ce{Fe2O3}$، ده 80% منها لا أكتر. يبقى نسبة الـ Fe في العينة = 80/100 × 70 = 56%. والرقم ده داخل في المدى اللي الكتاب بيديه للـ hematite، 50-60%. الشوائب بتزوّد الكتلة من غير ما تزوّد iron. إجابات غلط متوقعة: 70% (نسيت الشوائب) أو 80% (اعتبرت نسبة الـ compound هي نسبة الـ iron)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":50,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.ores-3","kind":"question","version":1,"ord":394,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.ores","concepts":[{"concept_id":"fe.ores","role":"primary"}],"title":"chem-s3-en.question-fe.ores-3","payload":{"stem":"According to the book, two of the important iron ores are found in the Oasis area. Which statement compares these two ores correctly?","tags":["compare"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Both contain iron in oxidation state +3, but only one of them contains water of crystallization.","correct":true},{"id":"b","text":"One of them is an iron oxide and the other is an iron carbonate.","correct":false},{"id":"c","text":"One of them is black and has magnetic properties.","correct":false},{"id":"d","text":"Both are hydrated iron (III) oxides with the same formula.","correct":false}],"book_ref":"Ch.1 'IRON', table of the most important iron ores, p.16 (place of deposits, chemical names)","difficulty":3,"concept_ids":["fe.ores"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: the Oasis ores are hematite, $\\ce{Fe2O3}$, and limonite, $\\ce{2Fe2O3.3H2O}$; iron is +3 in both, and of the two, only limonite holds water of crystallization."},"b":{"why":"The book's table gives no place of deposits for the carbonate ore. The two ores it places in the Oasis area are hematite and limonite.","feedback":"Misconception: Siderite is one of the Oasis ores."},"c":{"why":"The book places the black magnetic ore, magnetite, in the Eastern Desert, not in the Oasis area.","feedback":"Misconception: Magnetite is found in the Oasis area."},"d":{"why":"The two formulas in the table differ: only limonite's has a water part after a dot.","feedback":"Misconception: Hematite and limonite are the same compound."}},"explanation":"The book places hematite and limonite in the Oasis area (Western Desert). Hematite is iron (III) oxide, $\\ce{Fe2O3}$. Limonite is hydrated iron (III) oxide, $\\ce{2Fe2O3.3H2O}$. So iron is +3 in both. Only limonite holds water of crystallization. Magnetite is in the Eastern Desert. Siderite, the carbonate, has no place given. Common slip: putting magnetite in the Oasis area."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ ores بتاعة الواحات هما الـ hematite، $\\ce{Fe2O3}$، والـ limonite، $\\ce{2Fe2O3.3H2O}$؛ الـ iron عنده +3 في الاتنين، ومن الاتنين دول الـ limonite لوحده هو اللي فيه water of crystallization."},"b":{"why":"جدول الكتاب مش بيدي مكان رواسب للـ ore الـ carbonate (الـ siderite)، فهو مش من ores الواحات.","feedback":"الفكرة الغلط: إن الـ Siderite واحد من الـ ores بتاعة الواحات."},"c":{"why":"الكتاب بيحط الـ ore الأسود المغناطيسي (الـ magnetite) في الصحرا الشرقية، مش في منطقة الواحات.","feedback":"الفكرة الغلط: إن الـ Magnetite موجود في منطقة الواحات."},"d":{"why":"الـ formulas الاتنين في الجدول مختلفين: الـ limonite بس هو اللي فيه جزء مية بعد النقطة.","feedback":"الفكرة الغلط: إن الـ Hematite والـ limonite هما نفس الـ compound."}},"explanation":"الكتاب بيحط الـ hematite والـ limonite في منطقة الواحات (الصحرا الغربية). الـ Hematite هو iron (III) oxide، يعني $\\ce{Fe2O3}$. والـ Limonite هو hydrated iron (III) oxide، يعني $\\ce{2Fe2O3.3H2O}$. يبقى الـ iron عنده +3 في الاتنين. والـ limonite لوحده هو اللي فيه water of crystallization. الـ Magnetite في الصحرا الشرقية. والـ Siderite، اللي هو الـ carbonate، مالوش مكان مذكور. غلطة بتتكرر: إنك تحط الـ magnetite في منطقة الواحات."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":51,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.ore-dressing-3","kind":"question","version":1,"ord":395,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.ore-dressing","concepts":[{"concept_id":"fe.ore-dressing","role":"primary"}],"title":"chem-s3-en.question-fe.ore-dressing-3","payload":{"stem":"A magnetite ore is mixed with sand. The sand contains no iron. Which process removes the sand, and what happens to the iron percentage of the ore?","tags":["choose","two-step"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Concentrating by magnetic separation; the iron percentage increases.","correct":true},{"id":"b","text":"Concentrating by magnetic separation; the iron percentage stays the same, because no iron is removed.","correct":false},{"id":"c","text":"Roasting in air; the sand is oxidized and leaves as a gas.","correct":false},{"id":"d","text":"Sintering; the fine sand particles are collected into larger pieces.","correct":false}],"book_ref":"Ch.1 'Extraction of Iron from its Ores', Firstly: Ore dressing, 1- a, b, c, p.17 (c- Concentrating processes); magnetite properties, table p.16","difficulty":3,"concept_ids":["fe.ore-dressing"],"est_seconds":70},"layer":{"choices":{"a":{"why":"Right: sand is mixed with the ore, and magnetite is magnetic while sand is not, so magnetic separation removes the sand; the total mass falls, so the iron percentage increases."},"b":{"why":"The iron mass stays the same, but the total mass falls when the sand leaves, so iron's share of the mass, the iron percentage, increases.","feedback":"Misconception: The iron percentage depends only on the mass of iron."},"c":{"why":"Roasting oxidizes impurities such as sulphur; sand is mixed with the ore, and mixed impurities are removed by concentrating processes such as magnetic separation.","feedback":"Misconception: Impurities mixed with the ore are removed chemically, by roasting."},"d":{"why":"Sintering changes the size of the particles; it does not take anything out of the ore.","feedback":"Misconception: Sintering removes impurities."}},"explanation":"Sand is an impurity mixed with the ore, not combined with it. Concentrating processes remove such impurities by surface tension, magnetic or electric separation. Magnetite has magnetic properties and sand does not, so a magnet separates them. The mass of iron stays the same, but the total mass falls. So the iron percentage increases. Common slip: thinking the percentage cannot change because no iron is added."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الرمل مخلوط بالـ ore، والـ magnetite مغناطيسي والرمل لأ، فالـ magnetic separation بيشيل الرمل؛ والكتلة الكلية بتقل، فنسبة الـ iron بتزيد."},"b":{"why":"كتلة الـ iron بتفضل ثابتة، لكن الكتلة الكلية بتقل لما الرمل يمشي، فنصيب الـ iron منها، يعني نسبة الـ iron، بتزيد.","feedback":"الفكرة الغلط: إن نسبة الـ iron بتعتمد على كتلة الـ iron بس."},"c":{"why":"الـ roasting بيأكسد شوائب زي الـ sulphur؛ إنما الرمل مخلوط بالـ ore، والشوائب المخلوطة بتتشال بالـ concentrating processes زي الـ magnetic separation.","feedback":"الفكرة الغلط: إن الشوائب المخلوطة بالـ ore بتتشال كيميائيًا، بالـ roasting."},"d":{"why":"الـ sintering بيغيّر حجم الحبيبات؛ مش بيطلّع أي حاجة من الـ ore.","feedback":"الفكرة الغلط: إن الـ sintering بيشيل الشوائب."}},"explanation":"الرمل شوائب مخلوطة بالـ ore، مش متحدة معاه. والـ concentrating processes بتشيل الشوائب دي بالـ surface tension أو الـ magnetic separation أو الـ electric separation. الـ magnetite ليه خواص مغناطيسية والرمل لأ، فالمغناطيس بيفصلهم عن بعض. كتلة الـ iron بتفضل زي ما هي، لكن الكتلة الكلية بتقل، فنسبة الـ iron بتزيد. غلطة بتتكرر: إنك تفتكر إن النسبة مش ممكن تتغيّر طالما مفيش iron اتضاف."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":52,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.roasting-3","kind":"question","version":1,"ord":396,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.roasting","concepts":[{"concept_id":"fe.roasting","role":"primary"}],"title":"chem-s3-en.question-fe.roasting-3","payload":{"stem":"Give reasons: The iron percentage of limonite increases when it is roasted, although no iron is added.","tags":["exam-style","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) Heating drives off the water of crystallization as vapour: $\\ce{2Fe2O3.3H2O(s) ->[\\Delta] 2Fe2O3(s) + 3H2O(v)}$. (2) The mass of iron stays the same. (3) The total mass of the solid decreases, so iron's share (percentage) increases.","book_ref":"Ch.1 'Extraction of Iron from its Ores', Firstly: Ore dressing, 2- Roasting, p.17 (limonite equation); exam form: give reasons","difficulty":3,"concept_ids":["fe.roasting"],"est_seconds":90},"layer":{"explanation":"Limonite is hydrated iron (III) oxide. Roasting drives its water of crystallization out as vapour. No iron leaves, so the mass of iron stays the same. But the total mass of the solid falls. The same iron in a smaller mass gives a larger percentage. Key words: water of crystallization, expelling humidity, mass of iron unchanged. Most likely wrong answer: 'heating makes more iron'. A reaction cannot create iron atoms."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ limonite هو hydrated iron (III) oxide. الـ roasting بيطرد الـ water of crystallization بتاعه على شكل vapour. مفيش iron بيخرج، فكتلة الـ iron بتفضل زي ما هي. لكن الكتلة الكلية للمادة الصلبة بتقل. ونفس الـ iron في كتلة أصغر يدي نسبة أكبر. الكلمات المفتاحية: water of crystallization، طرد الرطوبة، كتلة الـ iron مابتتغيرش. أشهر غلطة: 'التسخين بيعمل iron زيادة'. التفاعل مايقدرش يخلق ذرات iron."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":53,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.blast-furnace-reduction-3","kind":"question","version":2,"ord":397,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.blast-furnace-reduction","concepts":[{"concept_id":"fe.blast-furnace-reduction","role":"primary"}],"title":"chem-s3-en.question-fe.blast-furnace-reduction-3","payload":{"stem":"A student writes: \"Coke reduces the iron ore in the blast furnace.\" Which statement corrects the student, using the book's equations?","tags":["correct-the-statement"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Coke is first changed into carbon monoxide, and carbon monoxide takes the oxygen from $\\ce{Fe2O3}$.","correct":true},{"id":"b","text":"Coke burns to carbon dioxide, and carbon dioxide takes the oxygen from $\\ce{Fe2O3}$.","correct":false,"misconception_id":"fe.blast-furnace-reduction.mc2"},{"id":"c","text":"The student is right: hot coke reacts directly with $\\ce{Fe2O3}$ at higher than 700 °C.","correct":false,"misconception_id":"fe.blast-furnace-reduction.mc1"},{"id":"d","text":"Oxygen of the air reduces $\\ce{Fe2O3}$, and coke only heats the furnace.","correct":false}],"book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (a), p.18","difficulty":3,"concept_ids":["fe.blast-furnace-reduction"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: coke burns to $\\ce{CO2}$, which reacts with more coke to give CO, and CO reduces $\\ce{Fe2O3}$ to iron at higher than 700 °C."},"b":{"why":"The carbon in $\\ce{CO2}$ already holds all the oxygen it takes in these reactions. $\\ce{CO2}$ reacts next with more coke to give CO.","feedback":"Misconception: $\\ce{CO2}$ is the reducing agent."},"c":{"why":"Solid carbon is not a reactant in the book's reduction equation: carbon monoxide reduces the ore.","feedback":"Misconception: Coke (carbon) itself reduces the ore directly."},"d":{"why":"Reduction removes oxygen from the ore, so adding oxygen cannot do it.","feedback":"Misconception: Oxygen is the reducing agent."}},"explanation":"In the book's equations, the ore is reduced by carbon monoxide, not by coke. Coke burns: $\\ce{C + O2 -> CO2}$. Then $\\ce{CO2 + C -> 2CO}$. Carbon monoxide reduces the ore: $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$, at higher than 700 °C. CO gains oxygen, so it is the reducing agent. Coke is the fuel and the source of CO. Common slip: naming $\\ce{CO2}$, whose carbon already holds all the oxygen it takes here."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ coke بيتحرق ويدي $\\ce{CO2}$، والـ $\\ce{CO2}$ بيتفاعل مع coke تاني ويدي CO، والـ CO هو اللي بيختزل الـ $\\ce{Fe2O3}$ لـ iron عند أعلى من 700 °C."},"b":{"why":"الـ carbon اللي في الـ $\\ce{CO2}$ شايل خلاص كل الـ oxygen اللي ممكن ياخده في التفاعلات دي. والـ $\\ce{CO2}$ بيتفاعل بعد كده مع الـ coke ويدّي CO.","feedback":"الفكرة الغلط: إن الـ $\\ce{CO2}$ هو الـ reducing agent."},"c":{"why":"في معادلة الـ reduction في الكتاب، الـ carbon الصلب مش من الـ reactants؛ اللي بيختزل الـ ore هو الـ CO.","feedback":"الفكرة الغلط: إن الـ coke (الـ carbon) نفسه بيختزل الـ ore على طول."},"d":{"why":"الـ reduction بيشيل الـ oxygen من الـ ore، وإضافة oxygen مستحيل تعمل كده.","feedback":"الفكرة الغلط: إن الـ oxygen هو الـ reducing agent."}},"explanation":"في معادلات الكتاب، اللي بيختزل الـ ore هو الـ carbon monoxide، مش الـ coke. الـ coke بيتحرق: $\\ce{C + O2 -> CO2}$. وبعدين $\\ce{CO2 + C -> 2CO}$. والـ carbon monoxide هو اللي بيختزل الـ ore: $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$، عند أعلى من 700 °C. الـ CO بياخد oxygen، يبقى هو الـ reducing agent. والـ coke هو الوقود ومصدر الـ CO. غلطة بتتكرر: إنك تختار الـ $\\ce{CO2}$، مع إن الـ carbon بتاعه شايل خلاص كل الـ oxygen اللي ممكن ياخده هنا."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":54,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.midrex-reduction-3","kind":"question","version":1,"ord":398,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.midrex-reduction","concepts":[{"concept_id":"fe.midrex-reduction","role":"primary"},{"concept_id":"fe.blast-furnace-reduction","role":"secondary"}],"title":"chem-s3-en.question-fe.midrex-reduction-3","payload":{"stem":"Compare the blast furnace and the Midrex furnace. Classify each statement.","tags":["exam-style","compare","classify"],"type":"classify","bloom":"understand","answer":{"bf":["i1","i7"],"mx":["i2","i3","i5"],"both":["i4","i6"]},"choices":[{"id":"i1","text":"The reducing gas comes from coke.","misconception_id":"fe.midrex-reduction.mc2"},{"id":"i2","text":"Natural gas (93% methane) is the raw material of the reducing gases."},{"id":"i3","text":"Hydrogen is one of the reducing agents."},{"id":"i4","text":"Carbon monoxide is a reducing agent."},{"id":"i5","text":"Water vapour is one of the products of the reduction step."},{"id":"i6","text":"Iron (III) oxide is reduced to iron."},{"id":"i7","text":"$\\ce{CO2 + C -> 2CO}$ is one of its reactions."}],"book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (a), p.18 and (b), p.18; exam form: compare","categories":[{"id":"bf","label":"Blast furnace only"},{"id":"mx","label":"Midrex furnace only"},{"id":"both","label":"Both furnaces"}],"difficulty":3,"concept_ids":["fe.midrex-reduction","fe.blast-furnace-reduction"],"est_seconds":120},"layer":{"choices":{"i1":{"why":"Coke is the raw material of the blast furnace; the Midrex furnace starts from natural gas.","feedback":"Misconception: The Midrex furnace uses coke."},"i2":{"why":"The furnace fed with coke does not need methane. Natural gas is the raw material of the Midrex furnace.","feedback":"Misconception: Both furnaces use natural gas."},"i3":{"why":"Coke is carbon and has no hydrogen. The hydrogen comes from methane, the Midrex raw material.","feedback":"Misconception: Hydrogen reduces the ore in the blast furnace too."},"i4":{"why":"CO is a reactant in the reduction equation of the blast furnace and of the Midrex furnace.","feedback":"Misconception: CO reduces the ore in one furnace only."},"i5":{"why":"Water forms when hydrogen takes oxygen, and only the Midrex furnace uses hydrogen.","feedback":"Misconception: Water forms in every reduction of iron ore."},"i6":{"why":"The two furnaces do the same job: they start from the same ore and end with the same metal.","feedback":"Misconception: The two furnaces do different jobs."},"i7":{"why":"Here solid carbon (coke) reacts with $\\ce{CO2}$, and only the blast furnace has coke.","feedback":"Misconception: This step happens in the Midrex furnace too."}},"explanation":"Both furnaces reduce iron (III) oxide to iron, and carbon monoxide is a reducing agent in both. They differ in the source of the reducing agent. Blast furnace: coke gives CO, through $\\ce{C + O2 -> CO2}$ and $\\ce{CO2 + C -> 2CO}$. Midrex furnace: natural gas gives water gas, CO + $\\ce{H2}$. Hydrogen takes oxygen and becomes water vapour, so $\\ce{H2O}$ is a Midrex product only. Common slip: putting CO in the blast furnace only."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"i1":{"why":"الـ coke هو المادة الخام اللي بتدّي الـ CO في الـ blast furnace، أما الـ Midrex furnace فبيبدأ من الـ natural gas.","feedback":"الفكرة الغلط: إن الـ Midrex furnace بيستخدم coke."},"i2":{"why":"الفرن اللي بيتغذّى على coke مش محتاج methane؛ الـ natural gas هو المادة الخام بتاعة الـ Midrex furnace بس.","feedback":"الفكرة الغلط: إن الفرنين الاتنين بيستخدموا natural gas."},"i3":{"why":"الـ coke ده carbon ومفيهوش ذرات hydrogen؛ الـ hydrogen جاي من الـ methane اللي في الـ natural gas.","feedback":"الفكرة الغلط: إن الـ hydrogen بيختزل الـ ore في الـ blast furnace هو كمان."},"i4":{"why":"الـ CO داخل في معادلة الـ reduction بتاعة الفرنين الاتنين، مش في فرن واحد بس.","feedback":"الفكرة الغلط: إن الـ CO بيختزل الـ ore في فرن واحد لوحده."},"i5":{"why":"المية بتتكوّن لما الـ hydrogen ياخد oxygen، والـ hydrogen بيستخدمه الـ Midrex furnace بس.","feedback":"الفكرة الغلط: إن المية بتتكوّن في أي reduction للـ iron ore."},"i6":{"why":"الفرنين الاتنين شغلانتهم واحدة: بيختزلوا الـ iron (III) oxide لـ iron.","feedback":"الفكرة الغلط: إن الفرنين بيعملوا شغلانتين مختلفتين."},"i7":{"why":"التفاعل ده محتاج carbon صلب يتفاعل مع الـ $\\ce{CO2}$، والـ carbon الصلب (الـ coke) موجود في الـ blast furnace بس.","feedback":"الفكرة الغلط: إن الخطوة دي بتحصل في الـ Midrex furnace كمان."}},"explanation":"الفرنين الاتنين بيختزلوا الـ iron (III) oxide لـ iron، والـ carbon monoxide هو reducing agent في الاتنين. الفرق بينهم في مصدر الـ reducing agent. الـ blast furnace: الـ coke بيدّي CO، عن طريق $\\ce{C + O2 -> CO2}$ و $\\ce{CO2 + C -> 2CO}$. الـ Midrex furnace: الـ natural gas بيدّي water gas، يعني CO + $\\ce{H2}$. الـ hydrogen بياخد oxygen ويبقى water vapour، عشان كده الـ $\\ce{H2O}$ product في الـ Midrex تحديدًا. غلطة بتتكرر: إنك تحط الـ CO في الـ blast furnace لوحده."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":55,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.steel-production-3","kind":"question","version":2,"catalog_version":1,"ord":399,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.steel-production","concepts":[{"concept_id":"fe.steel-production","role":"primary"},{"concept_id":"fe.midrex-reduction","role":"secondary"}],"title":"chem-s3-en.question-fe.steel-production-3","payload":{"stem":"The diagram shows the production of steel from iron ore. Which choice identifies furnaces X and Y?","tags":["exam-style","diagram","two-step"],"type":"mcq","bloom":"analyze","figure":{"root":"f","elements":{"f":{"type":"FlowDiagram","props":{"edges":[{"to":"fe","from":"ore","label":"Furnace X: products iron, $\\ce{CO2}$ and $\\ce{H2O}$"},{"to":"st","from":"fe","label":"Furnace Y: impurities removed, some elements added"}],"nodes":[{"id":"ore","label":"Iron ore"},{"id":"fe","label":"Iron"},{"id":"st","label":"Steel"}],"layout":"horizontal","caption":"From iron ore to steel"},"children":[]}}},"choices":[{"id":"a","text":"X: Midrex furnace; Y: oxygen converter","correct":true},{"id":"b","text":"X: blast furnace; Y: open-hearth furnace","correct":false},{"id":"c","text":"X: Midrex furnace; Y: blast furnace","correct":false,"misconception_id":"fe.steel-production.mc2"},{"id":"d","text":"X: electric furnace; Y: Midrex furnace","correct":false}],"book_ref":"Ch.1 'Thirdly: Iron Production' and 'Steel', p.18; Midrex furnace (b), p.18; exam form: read a diagram","difficulty":4,"concept_ids":["fe.steel-production","fe.midrex-reduction"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: water vapour on arrow X means the ore was reduced by CO and $\\ce{H2}$, as in the Midrex furnace. Y turns iron into steel, as an oxygen converter does."},"b":{"why":"The blast furnace reduces with CO from coke, which gives $\\ce{CO2}$ but no water vapour. Furnace X also gives $\\ce{H2O}$, so its reduction used hydrogen as well.","feedback":"Misconception: The blast furnace uses CO and $\\ce{H2}$ from natural gas."},"c":{"why":"Furnace Y starts from iron, not ore. A blast furnace reduces ore; it does not remove impurities and add elements.","feedback":"Misconception: The blast furnace produces steel."},"d":{"why":"The arrows go from ore to iron to steel, so X reduces ore and Y works on iron. An electric furnace makes steel from iron, and a Midrex furnace reduces ore, so this pair is reversed.","feedback":"Misconception: Steel furnaces reduce the ore, and reduction furnaces make steel."}},"explanation":"Two clues. Furnace X gives iron, $\\ce{CO2}$ and $\\ce{H2O}$. Water vapour means the ore was reduced by $\\ce{H2}$ as well as CO: the water gas made from natural gas in the Midrex furnace, $\\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$. The blast furnace reduces with CO from coke, so it gives only $\\ce{CO2}$ with the iron. Furnace Y turns iron into steel by removing impurities and adding elements. Steel furnaces are the oxygen converters, the open-hearth furnace and the electric furnace. So Y can be an oxygen converter. Common slip: calling the blast furnace a steel furnace."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: وجود الـ water vapour على السهم X معناه إن الـ ore اتعمله reduce بالـ CO والـ $\\ce{H2}$، زي ما بيحصل في الـ Midrex furnace. والـ Y بيحوّل الـ iron لـ steel، زي الـ oxygen converter."},"b":{"why":"الـ blast furnace بيعمل reduce بالـ CO اللي جاي من الـ coke، وده بيدّي $\\ce{CO2}$ من غير water vapour. لكن الـ Furnace X بيدّي $\\ce{H2O}$ كمان، يعني الـ reduction فيه استخدم hydrogen كمان.","feedback":"الفكرة الغلط: إن الـ blast furnace بيستخدم CO و $\\ce{H2}$ جايين من الـ natural gas."},"c":{"why":"الـ Furnace Y بيبدأ من الـ iron، مش من الـ ore، وبيشيل impurities ويضيف elements؛ الـ blast furnace بيعمل reduce للـ ore، فمش فرن steel.","feedback":"الفكرة الغلط: إن الـ blast furnace بيطلّع steel."},"d":{"why":"الأسهم ماشية من الـ ore للـ iron للـ steel، يعني X بيعمل reduce للـ ore و Y بيشتغل على الـ iron. الـ electric furnace بيعمل steel من الـ iron، والـ Midrex furnace بيعمل reduce للـ ore، فالاتنين هنا في المكان المقلوب.","feedback":"الفكرة الغلط: إن أفران الـ steel هي اللي بتعمل reduce للـ ore، وأفران الـ reduction هي اللي بتعمل steel."}},"explanation":"فيه دليلين. الـ Furnace X بيدّي iron و $\\ce{CO2}$ و $\\ce{H2O}$. وجود الـ water vapour معناه إن الـ ore اتعمله reduce بالـ $\\ce{H2}$ مع الـ CO: ده الـ water gas اللي بيتعمل من الـ natural gas في الـ Midrex furnace، $\\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$. إنما الـ blast furnace بيعمل reduce بالـ CO اللي جاي من الـ coke، فبيدّي $\\ce{CO2}$ لوحده مع الـ iron. والـ Furnace Y بيحوّل الـ iron لـ steel، بإنه يشيل الـ impurities ويضيف elements. أفران الـ steel هي الـ oxygen converters والـ open-hearth furnace والـ electric furnace. يبقى الـ Y ممكن يكون oxygen converter. غلطة بتتكرر: إنك تعتبر الـ blast furnace فرن steel."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":56,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.production","section_title":"Iron Production (steel)","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Iron Production (steel)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.ores-4","kind":"question","version":1,"ord":400,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.ores","concepts":[{"concept_id":"fe.ores","role":"primary"}],"title":"chem-s3-en.question-fe.ores-4","payload":{"stem":"An iron ore has a yellowish grey colour. When it is heated strongly, carbon dioxide gas is given off. What is this ore, and what is its formula?","tags":["exam-style","two-step"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Siderite, $\\ce{FeCO3}$","correct":true},{"id":"b","text":"Limonite, $\\ce{2Fe2O3.3H2O}$","correct":false},{"id":"c","text":"Hematite, $\\ce{Fe2O3}$","correct":false},{"id":"d","text":"Siderite, $\\ce{Fe2(CO3)3}$","correct":false}],"book_ref":"Ch.1 'IRON', table of the most important iron ores, p.16; roasting of siderite, p.17; exam form: two-step MCQ","difficulty":3,"concept_ids":["fe.ores"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: the yellowish grey colour is siderite's, and the $\\ce{CO2}$ on heating shows a carbonate: iron (II) carbonate, $\\ce{FeCO3}$."},"b":{"why":"Limonite is yellow too, but its heating gives off water vapour, not carbon dioxide.","feedback":"Misconception: Any yellowish ore is limonite; the gas evidence is ignored."},"c":{"why":"Hematite is not yellowish grey, and $\\ce{Fe2O3}$ contains no carbon to give $\\ce{CO2}$.","feedback":"Misconception: Any iron ore gives off a gas when heated."},"d":{"why":"The table names siderite iron (II) carbonate ($\\ce{FeCO3}$), so a formula with iron (III) does not fit.","feedback":"Misconception: Iron is +3 in every ore, so siderite is iron (III) carbonate."}},"explanation":"Two clues. The colour, yellowish grey, belongs to siderite. The gas confirms it: of these ores, only the carbonate gives off $\\ce{CO2}$ when heated. Siderite is iron (II) carbonate, $\\ce{FeCO3}$. On heating: $\\ce{FeCO3 ->[\\Delta] FeO + CO2}$. Limonite is yellow, but its heating gives water vapour. Common slip: choosing limonite from the colour alone."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: اللون الرمادي المصفرّ ده بتاع الـ siderite، والـ $\\ce{CO2}$ اللي بيطلع مع التسخين بيقول إنه carbonate: يعني iron (II) carbonate، $\\ce{FeCO3}$."},"b":{"why":"الـ Limonite لونه أصفر هو كمان، لكن لما يتسخن بيطلّع water vapour، مش carbon dioxide.","feedback":"الفكرة الغلط: إن أي ore لونه مايل للأصفر يبقى limonite، من غير ما تاخد بالك من دليل الغاز."},"c":{"why":"اللون مش بتاع الـ hematite، والـ $\\ce{Fe2O3}$ مافيهوش carbon أصلًا عشان يطلّع $\\ce{CO2}$.","feedback":"الفكرة الغلط: إن أي iron ore بيطلّع غاز لما يتسخن."},"d":{"why":"الاسم الكيميائي للـ siderite في الجدول iron (II) carbonate، والـ formula بتاعته $\\ce{FeCO3}$.","feedback":"الفكرة الغلط: إن الـ iron عنده +3 في كل الـ ores، فيبقى الـ siderite هو iron (III) carbonate."}},"explanation":"عندك دليلين. اللون الرمادي المصفرّ ده بتاع الـ siderite. والغاز بيأكد ده: من الـ ores دي، الـ carbonate لوحده هو اللي بيطلّع $\\ce{CO2}$ لما يتسخن. الـ Siderite هو iron (II) carbonate، يعني $\\ce{FeCO3}$. ولما يتسخن: $\\ce{FeCO3 ->[\\Delta] FeO + CO2}$. الـ Limonite لونه أصفر، لكن تسخينه بيطلّع water vapour. غلطة بتتكرر: إنك تختار الـ limonite من اللون لوحده."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":57,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.roasting-4","kind":"question","version":1,"ord":401,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.roasting","concepts":[{"concept_id":"fe.roasting","role":"primary"}],"title":"chem-s3-en.question-fe.roasting-4","payload":{"stem":"A limonite ore contains sulphur as an impurity. The ore is roasted (strongly heated in air). Which gases leave the ore?","tags":["choose","two-step"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Water vapour and $\\ce{SO2}$","correct":true},{"id":"b","text":"Water vapour and sulphur vapour","correct":false},{"id":"c","text":"$\\ce{CO2}$ and $\\ce{SO2}$","correct":false},{"id":"d","text":"Hydrogen, oxygen and $\\ce{SO2}$","correct":false}],"book_ref":"Ch.1 'Extraction of Iron from its Ores', Firstly: Ore dressing, 2- Roasting, p.17","difficulty":3,"concept_ids":["fe.roasting"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: roasting drives the water of crystallization out as vapour, and oxidizes sulphur to $\\ce{SO2}$."},"b":{"why":"Roasting happens in air, so sulphur does not leave unchanged: it reacts with oxygen first.","feedback":"Misconception: Roasting removes sulphur by melting or evaporating it."},"c":{"why":"$\\ce{CO2}$ comes from a carbonate, and limonite's formula contains no carbon.","feedback":"Misconception: Every ore gives off carbon dioxide when roasted."},"d":{"why":"Roasting drives the water out of the crystal as vapour; it does not break the water molecules apart.","feedback":"Misconception: Heating splits the water of crystallization into $\\ce{H2}$ and $\\ce{O2}$."}},"explanation":"Use both purposes of roasting on this ore. Drying: limonite loses its water of crystallization as vapour: $\\ce{2Fe2O3.3H2O -> 2Fe2O3 + 3H2O}$. Oxidation of impurities: sulphur reacts with oxygen of the air, $\\ce{S + O2 -> SO2}$. So water vapour and sulphur dioxide leave. Common slip: thinking sulphur simply melts out. It is oxidized."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ roasting بيطرد الـ water of crystallization على شكل vapour، وبيأكسد الـ sulphur لـ $\\ce{SO2}$."},"b":{"why":"الـ roasting بيحصل في الهوا، فالـ sulphur مابيخرجش زي ما هو: بيتفاعل مع الـ oxygen الأول.","feedback":"الفكرة الغلط: إن الـ roasting بيشيل الـ sulphur عن طريق إنه يدوّبه أو يبخّره."},"c":{"why":"الـ $\\ce{CO2}$ جاي من carbonate، والـ formula بتاعة الـ limonite مافيهاش carbon.","feedback":"الفكرة الغلط: إن أي ore بيطلّع carbon dioxide لما يتعمله roasting."},"d":{"why":"الـ roasting بيطرد المية من الـ crystal على شكل vapour، لكن مش بيكسّر الـ water molecules نفسها.","feedback":"الفكرة الغلط: إن التسخين بيكسّر الـ water of crystallization لـ $\\ce{H2}$ و $\\ce{O2}$."}},"explanation":"طبّق هدفين الـ roasting الاتنين على الـ ore ده. التجفيف: الـ limonite بيفقد الـ water of crystallization بتاعه على شكل vapour: $\\ce{2Fe2O3.3H2O -> 2Fe2O3 + 3H2O}$. وأكسدة الشوائب: الـ sulphur بيتفاعل مع الـ oxygen اللي في الهوا، $\\ce{S + O2 -> SO2}$. يبقى اللي بيخرج water vapour و sulphur dioxide. غلطة بتتكرر: إنك تفتكر إن الـ sulphur بيسيح ويخرج وخلاص. لأ، ده بيحصله oxidation."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":58,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.blast-furnace-reduction-4","kind":"question","version":1,"ord":402,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.blast-furnace-reduction","concepts":[{"concept_id":"fe.blast-furnace-reduction","role":"primary"}],"title":"chem-s3-en.question-fe.blast-furnace-reduction-4","payload":{"stem":"In the blast furnace, carbon monoxide reduces iron (III) oxide. Which choice gives the condition and the products of this reaction?","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"Higher than 700 °C; Fe and $\\ce{CO2}$","correct":true},{"id":"b","text":"Higher than 700 °C; Fe and $\\ce{O2}$","correct":false},{"id":"c","text":"Room temperature; Fe and $\\ce{CO2}$","correct":false},{"id":"d","text":"Higher than 700 °C; Fe and C","correct":false}],"book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (a), p.18; exam form: choose","difficulty":2,"concept_ids":["fe.blast-furnace-reduction"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right: the book writes higher than 700 °C over the arrow, and each CO takes one oxygen atom from the ore, giving Fe and $\\ce{CO2}$."},"b":{"why":"The oxygen leaving the ore does not escape alone. Carbon monoxide takes it and becomes $\\ce{CO2}$.","feedback":"Misconception: Reduction releases the ore's oxygen as oxygen gas."},"c":{"why":"The book's equation has higher than 700 °C written over the arrow, so heat is needed.","feedback":"Misconception: Carbon monoxide reduces the ore without heating."},"d":{"why":"CO does not lose its carbon here. It gains one oxygen atom from the ore.","feedback":"Misconception: Carbon monoxide gives up its carbon to the ore."}},"explanation":"The book's equation: $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$, at higher than 700 °C. Each CO takes one oxygen atom from the ore and becomes $\\ce{CO2}$. The iron oxide loses its oxygen and becomes iron. Common slip: writing $\\ce{O2}$ as a product, as if the oxygen simply left the ore."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الكتاب كاتب أعلى من 700 °C فوق السهم، وكل CO بياخد ذرة oxygen واحدة من الـ ore، فيطلع Fe و $\\ce{CO2}$."},"b":{"why":"الـ oxygen اللي بيسيب الـ ore مابيطلعش لوحده: الـ CO بياخده ويتحوّل لـ $\\ce{CO2}$.","feedback":"الفكرة الغلط: إن الـ reduction بيطلّع الـ oxygen اللي في الـ ore على شكل oxygen gas."},"c":{"why":"الشرط المكتوب فوق السهم في معادلة الكتاب أعلى من 700 °C، يعني التفاعل محتاج حرارة.","feedback":"الفكرة الغلط: إن الـ carbon monoxide بيختزل الـ ore من غير تسخين."},"d":{"why":"الـ CO هنا مابيخسرش ذرات؛ هو بياخد ذرة oxygen من الـ ore.","feedback":"الفكرة الغلط: إن الـ carbon monoxide بيدّي الـ carbon بتاعه للـ ore."}},"explanation":"معادلة الكتاب: $\\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$، عند أعلى من 700 °C. كل CO بياخد ذرة oxygen واحدة من الـ ore ويبقى $\\ce{CO2}$. والـ iron oxide بيخسر الـ oxygen بتاعه ويبقى iron. غلطة بتتكرر: إنك تكتب $\\ce{O2}$ كـ product، كأن الـ oxygen خرج من الـ ore وخلاص."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":59,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.midrex-reduction-4","kind":"question","version":2,"ord":403,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"fe.midrex-reduction","concepts":[{"concept_id":"fe.midrex-reduction","role":"primary"}],"title":"chem-s3-en.question-fe.midrex-reduction-4","payload":{"stem":"Which gases reduce the iron oxide in the Midrex furnace, and what do they change into?","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"CO and $\\ce{H2}$; they change into $\\ce{CO2}$ and $\\ce{H2O}$","correct":true},{"id":"b","text":"$\\ce{CH4}$ and $\\ce{CO2}$; they change into CO and $\\ce{H2}$","correct":false,"misconception_id":"fe.midrex-reduction.mc1"},{"id":"c","text":"CO only; it changes into $\\ce{CO2}$, while $\\ce{H2}$ only heats the furnace","correct":false},{"id":"d","text":"$\\ce{H2}$ only; it changes into $\\ce{H2O}$, because the furnace uses no coke","correct":false}],"book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (b), p.18; exam form: choose","difficulty":2,"concept_ids":["fe.midrex-reduction"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: water gas, CO and $\\ce{H2}$, reduces the ore; CO gains oxygen and becomes $\\ce{CO2}$, and $\\ce{H2}$ gains oxygen and becomes $\\ce{H2O}$."},"b":{"why":"That is the step that makes the reducing gases. The gases that then meet the iron oxide are not methane and $\\ce{CO2}$ but those it gives: water gas.","feedback":"Misconception: Methane itself reduces the ore."},"c":{"why":"The Midrex reduction gives $\\ce{H2O}$, and that water comes from $\\ce{H2}$ taking oxygen from the ore.","feedback":"Misconception: Only CO reduces the ore; hydrogen is just a fuel."},"d":{"why":"There is no coke, true, but carbon monoxide comes from methane: the water gas equation gives it.","feedback":"Misconception: No coke means no carbon monoxide."}},"explanation":"Natural gas gives water gas, a mixture of CO and $\\ce{H2}$. Both are reducing agents: $\\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$. CO gains oxygen and becomes $\\ce{CO2}$. $\\ce{H2}$ gains oxygen and becomes $\\ce{H2O}$. Common slip: thinking the Midrex furnace has no CO because it uses no coke."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ water gas، يعني CO و $\\ce{H2}$، هو اللي بيختزل الـ ore؛ الـ CO بياخد oxygen ويبقى $\\ce{CO2}$، والـ $\\ce{H2}$ بياخد oxygen ويبقى $\\ce{H2O}$."},"b":{"why":"دي الخطوة اللي بتعمل الغازات المختزلة، مش خطوة الـ reduction. الـ methane والـ $\\ce{CO2}$ مش هما اللي بيقابلوا الـ iron oxide ويختزلوه.","feedback":"الفكرة الغلط: إن الـ methane نفسه بيختزل الـ ore."},"c":{"why":"الـ $\\ce{H2O}$ اللي في products الـ reduction في الـ Midrex جاي من الـ $\\ce{H2}$ لما بياخد oxygen، يعني الـ hydrogen بيختزل الـ ore هو كمان، مش مجرد وقود.","feedback":"الفكرة الغلط: إن الـ CO لوحده بيختزل الـ ore، والـ hydrogen مجرد وقود."},"d":{"why":"مفيش coke، ده صح. لكن الـ carbon monoxide بييجي من الـ methane، زي ما معادلة الـ water gas بتوضّح.","feedback":"الفكرة الغلط: إن مفيش coke يعني مفيش carbon monoxide."}},"explanation":"الـ natural gas بيدّي water gas، اللي هو خليط من CO و $\\ce{H2}$. الاتنين reducing agents: $\\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$. الـ CO بياخد oxygen ويبقى $\\ce{CO2}$. والـ $\\ce{H2}$ بياخد oxygen ويبقى $\\ce{H2O}$. غلطة بتتكرر: إنك تفتكر إن الـ Midrex furnace مفيهوش CO عشان مش بيستخدم coke."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":60,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.oxidation-states-trend-5","kind":"question","version":1,"ord":404,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"te.oxidation-states-trend","concepts":[{"concept_id":"te.oxidation-states-trend","role":"primary"}],"title":"chem-s3-en.question-te.oxidation-states-trend-5","payload":{"stem":"Which of the following oxidation states is NOT shown by its element? ($_{21}$Sc, $_{22}$Ti, $_{26}$Fe, $_{29}$Cu)","tags":["exam-style","choose","book_ref:Ch.1 oxidation-states table + point 4, pp.8-9; Evaluation Q7.8, p.27"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Scandium (+4)","correct":true},{"id":"b","text":"Titanium (+4)","correct":false},{"id":"c","text":"Iron (+6)","correct":false},{"id":"d","text":"Copper (+2)","correct":false}],"book_ref":"Ch.1 oxidation-states table + point 4, pp.8-9; Evaluation Q7.8, p.27","difficulty":3,"concept_ids":["te.oxidation-states-trend"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: $\\ce{Sc^{3+}}$ already has the argon configuration. A fourth electron would come from the full 3p sublevel."},"b":{"why":"Ti is [Ar] $4s^2 3d^2$: losing four electrons removes its 4s and 3d electrons and leaves the argon configuration, with no inner electron removed.","feedback":"Misconception: The same charge is equally hard for neighbouring elements, so if one cannot reach +4, Ti cannot either."},"c":{"why":"Iron is +6 in $\\ce{Na2FeO4}$ (Na = +1, O = −2): its states above +3 are 'not important', but 'not important' does not mean 'not shown'.","feedback":"Misconception: Iron shows only its important states, +2 and +3."},"d":{"why":"Group IB is the book's exception to the group-number rule: copper is +2 in $\\ce{CuO}$.","feedback":"Misconception: The maximum state never exceeds the group number, so copper in group IB stops at +1."}},"explanation":"Scandium is [Ar] $4s^2 3d^1$. It loses the two 4s electrons and the one 3d electron to give $\\ce{Sc^{3+}}$. $\\ce{Sc^{3+}}$ has the stable argon configuration, with no 3d electrons left. A fourth electron would have to come from the complete 3p sublevel of an inner shell. That needs a very large energy, so $\\ce{Sc^{4+}}$ is not formed. Titanium is [Ar] $4s^2 3d^2$: losing four electrons also gives the argon configuration, as in $\\ce{TiO2}$. Iron shows +6 in $\\ce{Na2FeO4}$: 2(+1) + x + 4(−2) = 0, so x = +6. Its states above +3 are not important, but they exist. Copper shows +2 in $\\ce{CuO}$. Group IB is the exception: its maximum state exceeds its group number. Answer: scandium (+4)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ $\\ce{Sc^{3+}}$ واصل خلاص لتركيب الـ argon. وأي electron رابع هييجي من الـ 3p sublevel المليان."},"b":{"why":"الـ Ti هو [Ar] $4s^2 3d^2$. لما يفقد أربع electrons بيوصل لتركيب الـ argon من غير ما يتشال أي electron من جوه، فالـ titanium بيدّي +4 فعلًا.","feedback":"الفكرة الغلط: إن نفس الـ charge صعوبته واحدة على العناصر اللي جنب بعض، فلو عنصر مش قادر يوصل لـ +4، يبقى الـ Ti كمان مش هيقدر."},"c":{"why":"في $\\ce{Na2FeO4}$ (Na = +1، O = −2) الـ iron بيبقى +6. الكتاب بيقول إن الـ states اللي فوق +3 «مش مهمة»، ودي مش معناها «مش موجودة».","feedback":"الفكرة الغلط: إن الـ iron بيدي الـ states المهمة بتاعته تحديدًا، +2 و+3."},"d":{"why":"Group IB هو استثناء الكتاب من قاعدة رقم الـ group، والـ copper بيدّي +2 فعلًا في $\\ce{CuO}$.","feedback":"الفكرة الغلط: إن أعلى state عمره ما يعدّي رقم الـ group، فالـ copper اللي في group IB يقف عند +1."}},"explanation":"الـ scandium هو [Ar] $4s^2 3d^1$. بيفقد الـ 2 electrons بتوع الـ 4s والـ electron الوحيد اللي في الـ 3d، فيبقى $\\ce{Sc^{3+}}$. والـ $\\ce{Sc^{3+}}$ عنده تركيب الـ argon المستقر، ومافضلش فيه أي 3d electrons. أي electron رابع هيضطر ييجي من الـ 3p sublevel الكامل اللي في shell داخلي، وده محتاج طاقة كبيرة جدًا، فالـ $\\ce{Sc^{4+}}$ مابيتكوّنش. الـ titanium هو [Ar] $4s^2 3d^2$: لما يفقد أربع electrons برضه بيوصل لتركيب الـ argon، زي ما في $\\ce{TiO2}$. الـ iron بيدي +6 في $\\ce{Na2FeO4}$: 2(+1) + x + 4(−2) = 0، يعني x = +6. الـ states اللي فوق +3 عنده مش مهمة، لكنها موجودة. والـ copper بيدي +2 في $\\ce{CuO}$. Group IB هو الاستثناء: أعلى state فيه بيعدّي رقم الـ group. الإجابة: scandium (+4)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":72,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"8","relation":"based_on"}]},{"id":"chem-s3-en.question-te.oxidation-states-trend-6","kind":"question","version":1,"ord":405,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"te.oxidation-states-trend","concepts":[{"concept_id":"te.oxidation-states-trend","role":"primary"},{"concept_id":"fe.ores","role":"secondary"}],"title":"chem-s3-en.question-te.oxidation-states-trend-6","payload":{"stem":"In which iron ore is all the iron in oxidation state +2? (O = −2; the carbonate group $\\ce{CO3}$ = −2)","tags":["recall","choose"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Siderite, $\\ce{FeCO3}$","correct":true},{"id":"b","text":"Hematite, $\\ce{Fe2O3}$","correct":false},{"id":"c","text":"Limonite, $\\ce{2Fe2O3.3H2O}$","correct":false},{"id":"d","text":"Magnetite, $\\ce{Fe3O4}$","correct":false}],"book_ref":"Ch.1 oxidation states, pp.8-9; iron ores table, p.16","difficulty":2,"concept_ids":["te.oxidation-states-trend","fe.ores"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Correct! In $\\ce{FeCO3}$, Fe + (−2) = 0, so all the iron is +2: it is iron (II) carbonate."},"b":{"why":"Three O atoms give −6, balanced by two Fe atoms, so each Fe is +3.","feedback":"Misconception: Iron is +2 in all its oxides."},"c":{"why":"The water part is neutral and changes nothing: iron in the oxide part is +3, as in hematite.","feedback":"Misconception: Water of crystallization changes the oxidation state of iron."},"d":{"why":"Four O atoms give −8, and three Fe atoms at +2 would give +6, so not all the iron in magnetite can be +2.","feedback":"Misconception: More iron atoms per formula means a lower oxidation state of +2."}},"explanation":"The sum of oxidation states in a compound is zero. $\\ce{FeCO3}$: Fe + (−2) = 0, so Fe = +2. It is iron (II) carbonate. $\\ce{Fe2O3}$: 2Fe = +6, so Fe = +3. Limonite is the same oxide plus neutral water: +3. $\\ce{Fe3O4}$: 3Fe = +8, so not all the iron can be +2. You will see later that it holds both +2 and +3. Common slip: choosing magnetite."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! في الـ $\\ce{FeCO3}$، Fe + (−2) = 0، يبقى الـ iron كله +2: ده iron (II) carbonate."},"b":{"why":"تلات ذرات O بيدوا −6، وذرتين Fe لازم يوازنوا ده، فكل Fe بيبقى +3، مش +2.","feedback":"الفكرة الغلط: إن الـ iron بيبقى +2 في كل الـ oxides بتاعته."},"c":{"why":"جزء المية متعادل ومابيغيّرش حاجة، والـ iron في جزء الـ oxide بيبقى +3، مش +2.","feedback":"الفكرة الغلط: إن الـ water of crystallization بيغيّر الـ oxidation state بتاع الـ iron."},"d":{"why":"أربع ذرات O بيدوا −8، وتلات ذرات Fe لو كلها +2 هيدّوا +6 بس، فمش ممكن الـ iron كله يبقى +2 هنا.","feedback":"الفكرة الغلط: إن عدد ذرات iron أكتر في الصيغة معناه oxidation state أقل، +2."}},"explanation":"مجموع الـ oxidation states في أي compound بيساوي صفر. $\\ce{FeCO3}$: Fe + (−2) = 0، يعني Fe = +2، وده iron (II) carbonate. $\\ce{Fe2O3}$: 2Fe = +6، يعني Fe = +3. والـ limonite هو نفس الـ oxide ده ومعاه مية متعادلة: +3. $\\ce{Fe3O4}$: 3Fe = +8، يعني مش ممكن الـ iron كله يبقى +2؛ وهتشوف بعدين إن فيه +2 و+3 الاتنين. غلطة بتتكرر: إنك تختار الـ magnetite."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":73,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":8,"page_to":8,"section_key":"ch1.config.table","section_title":"Electron configurations and oxidation states table","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Electron configurations and oxidation states table"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-properties-5","kind":"question","version":2,"ord":406,"group_id":"chem-s3-en.ch1.practice.fe-extraction","primary_concept_id":"te.magnetic-properties","concepts":[{"concept_id":"te.magnetic-properties","role":"primary"},{"concept_id":"fe.ores","role":"secondary"}],"title":"chem-s3-en.question-te.magnetic-properties-5","payload":{"stem":"Classify the following substances into paramagnetic and diamagnetic substances. ($_{22}$Ti, $_{26}$Fe, $_{30}$Zn; $\\ce{Fe3O4}$ contains both $\\ce{Fe^2+}$ and $\\ce{Fe^3+}$ ions.)","tags":["recall","classify","exam-style"],"type":"classify","bloom":"apply","answer":{"dia":["x4","x5"],"para":["x1","x2","x3"]},"choices":[{"id":"x1","text":"Siderite, $\\ce{FeCO3}$"},{"id":"x2","text":"Magnetite, $\\ce{Fe3O4}$"},{"id":"x3","text":"Hematite, $\\ce{Fe2O3}$"},{"id":"x4","text":"$\\ce{ZnCO3}$"},{"id":"x5","text":"$\\ce{TiO2}$"}],"book_ref":"Ch.1 point 4 Magnetic properties, pp.13-14; iron ores table, p.16; Evaluation Q4 form, p.26","categories":[{"id":"para","label":"Paramagnetic"},{"id":"dia","label":"Diamagnetic"}],"difficulty":3,"concept_ids":["te.magnetic-properties","fe.ores"],"est_seconds":120},"layer":{"choices":{"x1":{"why":"Iron is +2 here: $\\ce{Fe^2+}$ has six 3d electrons, and 4 of them are unpaired.","feedback":"Misconception: Iron(II) has all its 3d electrons paired."},"x2":{"why":"It holds $\\ce{Fe^2+}$ (four unpaired 3d electrons) and $\\ce{Fe^3+}$ (five unpaired), so both of its iron ions have unpaired electrons.","feedback":"Misconception: A mixture of two ions cancels the magnetism."},"x3":{"why":"In $\\ce{Fe^3+}$ the five 3d electrons take one box each, so no pair forms and all 5 are unpaired.","feedback":"Misconception: A half-filled d sublevel has no unpaired electrons."},"x4":{"why":"Zinc is +2 here: the 3d sublevel of $\\ce{Zn^2+}$ is full, so it has no unpaired electrons.","feedback":"Misconception: Every compound of a metal from Sc to Zn is paramagnetic."},"x5":{"why":"Titanium is +4 here: $\\ce{Ti^4+}$ has no 3d electrons left, so it has no unpaired electrons.","feedback":"Misconception: Titanium compounds keep the atom's 3d electrons."}},"explanation":"A substance with unpaired electrons is paramagnetic; with all electrons paired, it is diamagnetic. $\\ce{Fe^2+}$ is [Ar] $3d^6$: 4 unpaired. $\\ce{Fe^3+}$ is [Ar] $3d^5$: 5 unpaired. So siderite, hematite and magnetite are paramagnetic. $\\ce{Zn^2+}$ is [Ar] $3d^{10}$: all paired. $\\ce{Ti^4+}$ is [Ar] $3d^0$: no d electrons. Both are diamagnetic. Common slip: calling every transition-metal compound paramagnetic."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"x1":{"why":"الـ iron هنا بـ +2. الـ $\\ce{Fe^2+}$ فيه ستة 3d electrons، منهم أربعة unpaired.","feedback":"الفكرة الغلط: إن الـ iron(II) كل الـ 3d electrons بتوعه paired."},"x2":{"why":"الـ magnetite فيه $\\ce{Fe^2+}$ (أربعة unpaired electrons في الـ 3d) و$\\ce{Fe^3+}$ (خمسة unpaired)، يعني الاتنين iron ions فيهم unpaired electrons.","feedback":"الفكرة الغلط: إن خليط من اتنين ions بيلغي الـ magnetism."},"x3":{"why":"الـ $\\ce{Fe^3+}$ فيه خمسة 3d electrons في خمس مربعات، واحد في كل مربع، فمفيش ولا واحد فيهم paired: الخمسة unpaired.","feedback":"الفكرة الغلط: إن الـ d sublevel اللي نصه مليان مفيهوش unpaired electrons."},"x4":{"why":"الـ zinc هنا بـ +2، والـ 3d sublevel بتاع الـ $\\ce{Zn^2+}$ مليان، فكل الـ electrons paired ومفيش unpaired electrons.","feedback":"الفكرة الغلط: إن أي compound لـ metal من الـ Sc للـ Zn لازم يكون paramagnetic."},"x5":{"why":"الـ titanium هنا بـ +4. الـ $\\ce{Ti^4+}$ مافضلش فيه أي 3d electrons، فمفيهوش unpaired electrons.","feedback":"الفكرة الغلط: إن الـ titanium compounds بتحتفظ بالـ 3d electrons بتوع الذرة."}},"explanation":"المادة اللي فيها unpaired electrons تبقى paramagnetic؛ واللي كل الـ electrons فيها paired تبقى diamagnetic. الـ $\\ce{Fe^2+}$ هو [Ar] $3d^6$: فيه 4 unpaired. والـ $\\ce{Fe^3+}$ هو [Ar] $3d^5$: فيه 5 unpaired. يبقى الـ siderite والـ hematite والـ magnetite كلهم paramagnetic. أما الـ $\\ce{Zn^2+}$ فهو [Ar] $3d^{10}$: كله paired. والـ $\\ce{Ti^4+}$ هو [Ar] $3d^0$: مفيهوش d electrons. الاتنين دول diamagnetic. غلطة بتتكرر: إنك تقول على أي transition-metal compound إنه paramagnetic."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":38,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-phys.electric-current-1","kind":"question","version":1,"ord":421,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"phys.electric-current","concepts":[{"concept_id":"phys.electric-current","role":"primary"}],"title":"chem-s3-en.question-phys.electric-current-1","payload":{"stem":"Which statement describes an electric current?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"A flow of electric charges through a conductor or a solution","correct":true},{"id":"b","text":"The energy stored inside a battery","correct":false},{"id":"c","text":"A flow of heat along a metal wire","correct":false},{"id":"d","text":"A flow of metal atoms along the wire","correct":false}],"book_ref":"Background for Ch.1 'Preparation of alloys', 2. By electro deposition, p.19 (Grade 9 physics)","difficulty":1,"concept_ids":["phys.electric-current"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Right: a current is a flow of electric charges: free electrons in a metal wire, ions in a solution."},"b":{"why":"A battery is the source that pushes the charges; the current is the charges moving in the wire.","feedback":"Misconception: The current is the battery's stored energy."},"c":{"why":"A wire may get warm, but that is a result. The current itself is carried by moving charges, free electrons in a metal wire.","feedback":"Misconception: Current is heat moving through a wire."},"d":{"why":"A wire does not wear away while it carries a current. The particles that move are free electrons, not metal atoms.","feedback":"Misconception: The metal atoms of the wire travel along it."}},"explanation":"An electric current is a flow of electric charges. In a metal wire, free electrons move. In a solution, ions move. A source such as a battery pushes the charges round a closed path. Common slip: thinking the current is the energy stored in the battery."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ current هو سريان electric charges: الـ free electrons في سلك الـ metal، والـ ions في الـ solution."},"b":{"why":"البطارية هي المصدر اللي بيزق، لكن الـ current هو حركة الـ charges نفسها في السلك، مش الطاقة المخزّنة.","feedback":"الفكرة الغلط: إن الـ current هو الطاقة المخزّنة في البطارية."},"c":{"why":"السلك ممكن يسخن، لكن ده نتيجة؛ الـ current هو سريان electric charges.","feedback":"الفكرة الغلط: إن الـ current هو حرارة ماشية في السلك."},"d":{"why":"السلك مش بيتآكل وهو شايل current، فالـ metal atoms مش هي اللي بتتحرك على طوله؛ اللي بيتحرك جسيمات أصغر.","feedback":"الفكرة الغلط: إن الـ metal atoms بتاعة السلك بتتحرك على طوله."}},"explanation":"الـ electric current هو سريان للـ electric charges. في سلك الـ metal، الـ free electrons هي اللي بتتحرك. وفي الـ solution، الـ ions هي اللي بتتحرك. ومصدر زي البطارية هو اللي بيزق الـ charges في مسار مقفول. غلطة بتتكرر: إنك تفتكر إن الـ current هو الطاقة المخزّنة في البطارية."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":11,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.preparation","section_title":"Preparation of alloys","section_path":["Transition Elements","Alloys","Preparation of alloys"],"relation":"beyond"}]},{"id":"chem-s3-en.question-phys.electric-current-2","kind":"question","version":1,"ord":422,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"phys.electric-current","concepts":[{"concept_id":"phys.electric-current","role":"primary"}],"title":"chem-s3-en.question-phys.electric-current-2","payload":{"stem":"Two metal plates dip into a solution that contains copper ions ($\\ce{Cu^2+}$) and zinc ions ($\\ce{Zn^2+}$). The plates are joined to a battery. Towards which plate do the metal ions move?","tags":["diagnostic","prerequisite","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Both kinds of ion move towards the plate joined to the negative terminal.","correct":true},{"id":"b","text":"Both kinds of ion move towards the plate joined to the positive terminal.","correct":false},{"id":"c","text":"They do not move; only electrons carry a current in a solution.","correct":false},{"id":"d","text":"Copper ions move to one plate and zinc ions to the other.","correct":false}],"book_ref":"Background for Ch.1 'Preparation of alloys', 2. By electro deposition, p.19 (Grade 9 physics)","difficulty":2,"concept_ids":["phys.electric-current"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: both ions are positive, and opposite charges attract, so both move towards the plate joined to the negative terminal."},"b":{"why":"Both ions carry a positive charge, and like charges repel, so the positive plate pushes them away.","feedback":"Misconception: Positive ions move to the positive plate."},"c":{"why":"Electrons carry the current in a metal wire, but in a solution the ions carry it, so the ions do move.","feedback":"Misconception: Only electrons can carry a current."},"d":{"why":"The kind of metal does not decide the direction; the sign of the charge does, and both ions are positive.","feedback":"Misconception: Ions of different metals move to different plates."}},"explanation":"In a solution, ions carry the current. Opposite charges attract. Both ions are positive, so both move towards the plate joined to the negative terminal. The kind of metal does not decide the direction; the charge does. This is why two metals can deposit together on one object."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ ions الاتنين positive، والـ charges المختلفة بتتجاذب، فالاتنين بيتحركوا ناحية اللوح المتوصّل بالـ negative terminal."},"b":{"why":"الـ ions الاتنين شايلين positive charge، والـ like charges بتتنافر، فاللوح الـ positive بيزقّهم بعيد.","feedback":"الفكرة الغلط: إن الـ positive ions بتروح للوح الـ positive."},"c":{"why":"الـ electrons هي اللي بتشيل الـ current في سلك الـ metal، لكن جوه الـ solution الـ ions هي اللي بتشيله، يعني الـ ions بتتحرك.","feedback":"الفكرة الغلط: إن مفيش غير الـ electrons اللي تقدر تشيل current."},"d":{"why":"نوع الـ metal مش هو اللي بيحدد الاتجاه، إشارة الـ charge هي اللي بتحدده، والـ ions الاتنين positive.","feedback":"الفكرة الغلط: إن ions الـ metals المختلفة بتروح لألواح مختلفة."}},"explanation":"في الـ solution، الـ ions هي اللي بتشيل الـ current. والـ charges المختلفة بتتجاذب. الـ ions الاتنين positive، فالاتنين بيتحركوا ناحية اللوح المتوصّل بالـ negative terminal. نوع الـ metal مش هو اللي بيحدد الاتجاه، الـ charge هي اللي بتحدده. وعشان كده اتنين metals يقدروا يترسّبوا مع بعض على نفس الجسم."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":12,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.preparation","section_title":"Preparation of alloys","section_path":["Transition Elements","Alloys","Preparation of alloys"],"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.electroplating-basic-1","kind":"question","version":1,"ord":423,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"chem.electroplating-basic","concepts":[{"concept_id":"chem.electroplating-basic","role":"primary"}],"title":"chem-s3-en.question-chem.electroplating-basic-1","payload":{"stem":"A steel car part is to be coated with chromium by electroplating. Which solution should be used?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"A solution that contains chromium ions","correct":true},{"id":"b","text":"A solution that contains iron ions","correct":false},{"id":"c","text":"Pure water","correct":false},{"id":"d","text":"Water with chromium metal powder stirred into it","correct":false}],"book_ref":"Background for Ch.1 'Preparation of alloys', 2. By electro deposition, p.19 (taught fully in Ch.4); chromium is used in metal plating, p.6","difficulty":1,"concept_ids":["chem.electroplating-basic"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right: the coat is made of the metal whose ions are in the solution. Positive chromium ions move to the part on the negative terminal and gain electrons there."},"b":{"why":"Iron is already in the steel part. The coat must be chromium, and the coat is made of the metal whose ions are in the solution.","feedback":"Misconception: The coat comes from the metal of the object."},"c":{"why":"A coat needs metal particles that can move. Pure water holds no metal ions, so no coat can form.","feedback":"Misconception: Any liquid can carry the current and coat the object."},"d":{"why":"Powder particles carry no charge, so the current cannot move them. The metal must be in the solution as ions.","feedback":"Misconception: Metal powder sticks to the object to form the coat."}},"explanation":"In electroplating, the coat is made of the metal whose ions are in the solution. The object is joined to the negative terminal. The positive chromium ions move to it. There they gain electrons and become chromium atoms. So the solution must contain chromium ions."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الطبقة بتتكوّن من الـ metal اللي الـ ions بتاعته في الـ solution. الـ chromium ions الـ positive بتتحرك ناحية القطعة اللي على الـ negative terminal وبتكسب electrons هناك."},"b":{"why":"الـ iron موجود أصلًا في القطعة الـ steel، والمطلوب إن الـ chromium هو اللي يظهر على سطحها. الطبقة بتيجي من الـ ions اللي في الـ solution.","feedback":"الفكرة الغلط: إن الطبقة بتيجي من الـ metal بتاع الجسم نفسه."},"c":{"why":"الطبقة محتاجة metal ions تقدر تتحرك، والمية النقية مفيهاش أي metal ions.","feedback":"الفكرة الغلط: إن أي سائل يقدر يشيل الـ current ويعمل طبقة على الجسم."},"d":{"why":"جسيمات البودرة مش شايلة charge، فالـ current مايقدرش يحرّكها. الـ metal لازم يكون على هيئة ions في الـ solution.","feedback":"الفكرة الغلط: إن بودرة الـ metal بتلزق في الجسم وتعمل الطبقة."}},"explanation":"في الـ electroplating، الطبقة بتتكوّن من الـ metal اللي الـ ions بتاعته موجودة في الـ solution. الجسم بيتوصّل بالـ negative terminal، فالـ chromium ions الـ positive بتتحرك ناحيته. وهناك بتكسب electrons وبتتحوّل لـ chromium atoms. يبقى الـ solution لازم يكون فيه chromium ions."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":13,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.preparation","section_title":"Preparation of alloys","section_path":["Transition Elements","Alloys","Preparation of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"relation":"beyond"}]},{"id":"chem-s3-en.question-chem.electroplating-basic-2","kind":"question","version":1,"ord":424,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"chem.electroplating-basic","concepts":[{"concept_id":"chem.electroplating-basic","role":"primary"}],"title":"chem-s3-en.question-chem.electroplating-basic-2","payload":{"stem":"A student wants to coat a spoon with copper. The spoon is joined to the positive terminal and a copper plate to the negative terminal, in copper (II) sulphate solution. After ten minutes, the spoon has no copper coat. What is the student's error?","tags":["diagnostic","prerequisite","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"The spoon should be joined to the negative terminal, where copper ions gain electrons.","correct":true},{"id":"b","text":"The solution should contain ions of the spoon's metal, not copper ions.","correct":false},{"id":"c","text":"The copper plate is not needed; the spoon alone should be in the solution.","correct":false},{"id":"d","text":"The terminals do not matter; the student should simply wait longer.","correct":false}],"book_ref":"Background for Ch.1 'Preparation of alloys', 2. By electro deposition, p.19 (taught fully in Ch.4)","difficulty":3,"concept_ids":["chem.electroplating-basic"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: the spoon must be the cathode (negative terminal). Positive copper ions are attracted to it and gain electrons there to form the copper coat."},"b":{"why":"The coat is made from the ions in the solution, and the student wants a copper coat. So copper ions are the right ions.","feedback":"Misconception: The coat comes from the metal of the object."},"c":{"why":"Charges cannot flow with only one plate in the solution. The second plate completes the circuit.","feedback":"Misconception: A current does not need a closed path."},"d":{"why":"Metal ions are positive. A positive plate repels positive ions, however long you wait.","feedback":"Misconception: Electroplating works on either terminal."}},"explanation":"In electroplating, the object must be the cathode: it is joined to the negative terminal. Copper ions are positive, so they are attracted to it. Each copper ion gains two electrons there and becomes a copper atom: $\\ce{Cu^2+ + 2e- -> Cu}$. Here the spoon was positive. It repelled the copper ions, so no coat formed."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: المعلقة لازم تبقى الـ cathode (الـ negative terminal). الـ copper ions الـ positive بتنجذب ليها وبتكسب electrons هناك وتكوّن طبقة الـ copper."},"b":{"why":"الطبقة بتتكوّن من الـ ions اللي في الـ solution، والطالب عايز طبقة copper، فالـ copper ions هي المناسبة.","feedback":"الفكرة الغلط: إن الطبقة بتيجي من الـ metal بتاع الجسم نفسه."},"c":{"why":"الـ charges مابتقدرش تسري ولوح واحد لوحده في الـ solution. اللوح التاني هو اللي بيكمّل المسار المقفول للـ current.","feedback":"الفكرة الغلط: إن الـ current مش محتاج مسار مقفول."},"d":{"why":"الـ metal ions positive، واللوح الـ positive بيزقّها بعيد عنه، فمش هيشدّها ناحيته مهما استنيت.","feedback":"الفكرة الغلط: إن الـ electroplating بيشتغل على أي terminal."}},"explanation":"في الـ electroplating، الجسم لازم يكون هو الـ cathode، يعني متوصّل بالـ negative terminal. الـ copper ions positive، فبتنجذب ناحيته. وهناك كل copper ion بيكسب 2 electrons وبيتحوّل لـ copper atom: $\\ce{Cu^2+ + 2e- -> Cu}$. هنا المعلقة كانت positive، فزقّت الـ copper ions بعيد عنها، وعشان كده مفيش طبقة اتكوّنت."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":14,"book_refs":[{"relation":"beyond"}]},{"id":"chem-s3-en.question-alloy.definition-preparation-1","kind":"question","version":1,"ord":425,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.definition-preparation","concepts":[{"concept_id":"alloy.definition-preparation","role":"primary"}],"title":"chem-s3-en.question-alloy.definition-preparation-1","payload":{"stem":"Write the scientific term: A material usually formed from two metals or more, which may also consist of a metal and a non-metal.","tags":["exam-style","scientific-term"],"type":"short","bloom":"remember","answer":"Alloy. Key points: two metals or more (such as ferrochromium or ferromanganese), or a metal and a non-metal, such as carbon in steel.","book_ref":"Ch.1 'ALLOYS' and 'Preparation of alloys', p.19; exam form: scientific term","difficulty":2,"concept_ids":["alloy.definition-preparation"],"est_seconds":30},"layer":{"explanation":"This is the book's definition of an alloy. Most alloys contain two metals or more, such as ferrochromium, ferromanganese, ferrovanadium and ferronickel. Some contain a non-metal: steel is iron with carbon. Common slip: answering 'compound'. An alloy is not always a chemical compound."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"ده تعريف الكتاب للـ alloy. أغلب الـ alloys فيها اتنين metals أو أكتر، زي الـ ferrochromium والـ ferromanganese والـ ferrovanadium والـ ferronickel. وفيه alloys فيها non-metal: الـ steel مثلًا هو iron مع carbon. غلطة بتتكرر: إنك تجاوب 'compound'. الـ alloy مش دايمًا chemical compound."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":15,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys","section_title":"Alloys","section_path":["Transition Elements","Alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.interstitial-1","kind":"question","version":1,"ord":426,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.interstitial","concepts":[{"concept_id":"alloy.interstitial","role":"primary"}],"title":"chem-s3-en.question-alloy.interstitial-1","payload":{"stem":"The table gives the atomic radius of four elements (made-up values). Which pair is most likely to form an interstitial alloy?","tags":["exam-style","data","new-case"],"type":"mcq","bloom":"apply","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["W","metal",1.24],["X","metal",1.25],["Y","non-metal",0.77],["Z","metal",1.6]],"caption":"Made-up values","headers":["Element","Kind","Atomic radius"]},"children":[]}}},"choices":[{"id":"a","text":"W with Y: Y atoms are small enough to enter the spaces of the W lattice.","correct":true},{"id":"b","text":"W with X: their atoms have almost the same radius.","correct":false},{"id":"c","text":"W with Z: the large Z atoms fill the spaces better.","correct":false},{"id":"d","text":"X with Z: an alloy must be made of two metals.","correct":false}],"book_ref":"Ch.1 'Types of alloys', 1-Interstitial alloys, fig 1-5, p.19","difficulty":4,"concept_ids":["alloy.interstitial"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right: Y (0.77) is much smaller than W (1.24), so Y atoms can enter the spaces of the W lattice, as carbon does in iron to make steel."},"b":{"why":"Atoms of nearly equal size take each other's places. In an interstitial alloy, small atoms enter the spaces instead.","feedback":"Misconception: Atoms of equal size form an interstitial alloy."},"c":{"why":"The spaces between W atoms are small, so an atom bigger than W cannot fit inside them.","feedback":"Misconception: Bigger atoms fit the spaces better."},"d":{"why":"An alloy need not be two metals: steel is iron with carbon, a non-metal.","feedback":"Misconception: Alloys contain metals only."}},"explanation":"In an interstitial alloy, atoms with a small atomic size enter the spaces of a metal's crystal lattice. Y (0.77) is much smaller than W (1.24), so it fits in the spaces. W and X have nearly equal radii: they suit a substitutional alloy. Steel is the book's example: small carbon atoms in the spaces of iron."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ Y (0.77) أصغر بكتير من الـ W (1.24)، فذرات الـ Y تقدر تدخل في فراغات الـ lattice بتاع الـ W، زي ما الـ carbon بيعمل في الـ iron عشان يطلع الـ steel."},"b":{"why":"الذرات اللي حجمها تقريبًا واحد بتاخد أماكن بعض، وده مش معنى 'interstitial'؛ الـ interstitial معناه ذرات صغيرة في الفراغات.","feedback":"الفكرة الغلط: إن الذرات اللي في نفس الحجم بتكوّن interstitial alloy."},"c":{"why":"الفراغات اللي بين ذرات الـ W صغيرة، وذرة أكبر من الـ W ماتقدرش تدخل جواها.","feedback":"الفكرة الغلط: إن الذرات الأكبر بتدخل في الفراغات أحسن."},"d":{"why":"مش لازم كل العناصر تبقى metals: الـ steel فيه carbon، وهو non-metal.","feedback":"الفكرة الغلط: إن الـ alloys مفيهاش غير metals."}},"explanation":"في الـ interstitial alloy، ذرات عنصر الـ atomic size بتاعه صغير بتدخل في فراغات الـ crystal lattice بتاع metal. الـ Y (0.77) أصغر بكتير من الـ W (1.24)، فيقدر يدخل في الفراغات. أما الـ W والـ X فالـ radii بتاعتهم تقريبًا متساوية: دول يناسبهم substitutional alloy. ومثال الكتاب هو الـ steel: ذرات carbon صغيرة في فراغات الـ iron."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":16,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.substitutional-1","kind":"question","version":1,"ord":427,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.substitutional","concepts":[{"concept_id":"alloy.substitutional","role":"primary"}],"title":"chem-s3-en.question-alloy.substitutional-1","payload":{"stem":"Metal M has an atomic radius of 1.24 (made-up value). Which of the following can replace some M atoms in its crystal lattice to form a substitutional alloy?","tags":["exam-style","choose","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Metal P: atomic radius 1.25, the same crystal lattice as M, similar chemical properties","correct":true},{"id":"b","text":"Metal Q: atomic radius 1.25, the same crystal lattice as M, very different chemical properties","correct":false},{"id":"c","text":"Element R: atomic radius 0.75, the same crystal lattice as M, similar chemical properties","correct":false},{"id":"d","text":"Metal T: atomic radius 1.60, a different crystal lattice, similar chemical properties","correct":false}],"book_ref":"Ch.1 'Types of alloys', 2-Substitutional alloys, p.20","difficulty":3,"concept_ids":["alloy.substitutional"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: P meets all three of the book's conditions: almost the same atomic radius as M (1.25 vs 1.24), the same crystal lattice and similar chemical properties."},"b":{"why":"Size and lattice match here, but the book lists a third condition: similar chemical properties. Q's are very different.","feedback":"Misconception: The same size and lattice are enough."},"c":{"why":"An atom this small fits in the spaces, so it would not take an M atom's place.","feedback":"Misconception: Small atoms replace the host atoms."},"d":{"why":"Similar properties help, but an atom this large, with a different lattice, cannot sit in an M atom's place.","feedback":"Misconception: Any two metals with similar properties can form this alloy."}},"explanation":"In a substitutional alloy, atoms of another metal replace some atoms of the pure metal. The book's three conditions: the same atomic radius, crystal lattice and chemical properties. Only metal P meets all three. Q fails on chemical properties. R is small enough to enter the spaces instead. T is too large and has another lattice."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ P محقق شروط الكتاب التلاتة: الـ atomic radius تقريبًا زي الـ M (1.25 قصاد 1.24)، ونفس الـ crystal lattice، و chemical properties متشابهة."},"b":{"why":"الحجم والـ lattice متطابقين هنا، لكن الكتاب بيذكر شرط تالت: نفس الـ chemical properties، والـ Q مختلف فيها جدًا.","feedback":"الفكرة الغلط: إن نفس الحجم ونفس الـ lattice كفاية."},"c":{"why":"ذرة صغيرة بالشكل ده بتدخل في الفراغات، فمش هتاخد مكان ذرة M.","feedback":"الفكرة الغلط: إن الذرات الصغيرة بتحل مكان ذرات الـ metal الأساسي."},"d":{"why":"الخواص المتشابهة بتساعد، لكن ذرة كبيرة كده، وفي lattice مختلف، ماتقدرش تقعد مكان ذرة M.","feedback":"الفكرة الغلط: إن أي اتنين metals خواصهم متشابهة يقدروا يكوّنوا الـ alloy ده."}},"explanation":"في الـ substitutional alloy، ذرات metal تاني بتحل مكان بعض ذرات الـ metal النقي. والكتاب بيحط 3 شروط: نفس الـ atomic radius، ونفس الـ crystal lattice، ونفس الـ chemical properties. الـ metal P لوحده هو اللي محقق التلاتة. الـ Q بيقع في الـ chemical properties. الـ R صغير كفاية إنه يدخل في الفراغات بدل كده. والـ T كبير زيادة وليه lattice تاني."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":17,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.intermetallic-1","kind":"question","version":2,"ord":428,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.intermetallic","concepts":[{"concept_id":"alloy.intermetallic","role":"primary"}],"title":"chem-s3-en.question-alloy.intermetallic-1","payload":{"stem":"Cementite ($\\ce{Fe3C}$) and the lead-gold alloy ($\\ce{Au2Pb}$) belong to the same type of alloy. What do they have in common?","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Their elements combine chemically to form a compound whose formula disobeys the valence law.","correct":true},{"id":"b","text":"Small atoms enter the spaces of the main metal's crystal lattice.","correct":false,"misconception_id":"alloy.intermetallic.mc2"},{"id":"c","text":"Atoms of one element replace atoms of the other because they have the same atomic radius.","correct":false},{"id":"d","text":"They are physical mixtures with no fixed ratio of atoms.","correct":false,"misconception_id":"alloy.intermetallic.mc1"}],"book_ref":"Ch.1 'Types of alloys', 3) Inter-metallic alloys, p.20","difficulty":2,"concept_ids":["alloy.intermetallic"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: both are intermetallic alloys. Their elements combine chemically into a compound, and the formulas $\\ce{Fe3C}$ and $\\ce{Au2Pb}$ disobey the valence law."},"b":{"why":"That describes steel, also iron and carbon. Steel has no fixed formula like $\\ce{Fe3C}$: its carbon atoms only sit in the spaces.","feedback":"Misconception: Cementite is interstitial like steel."},"c":{"why":"A carbon atom is much smaller than an iron atom, so it cannot take an iron atom's place. A fixed formula shows that the elements combine chemically.","feedback":"Misconception: Every two-element alloy is substitutional."},"d":{"why":"Each one has a formula with a fixed ratio, and a mixture has no fixed formula.","feedback":"Misconception: Intermetallic alloys are physical mixtures."}},"explanation":"Both are intermetallic alloys. Their elements combine chemically to form a chemical compound. The formulas $\\ce{Fe3C}$ and $\\ce{Au2Pb}$ disobey the valence law. Steel is also iron and carbon, but there the carbon atoms only sit in the spaces. So steel is interstitial, while cementite is intermetallic."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الاتنين intermetallic alloys. العناصر اللي فيهم بتتحد كيميائيًا وتكوّن compound، والـ formulas $\\ce{Fe3C}$ و$\\ce{Au2Pb}$ مش ماشية على الـ valence law."},"b":{"why":"ده وصف الـ steel، وهو كمان iron مع carbon. لكن الـ steel مالوش formula ثابتة زي $\\ce{Fe3C}$.","feedback":"الفكرة الغلط: إن الـ cementite نوعه interstitial زي الـ steel."},"c":{"why":"ذرة الـ carbon مش في حجم ذرة الـ iron. والـ formula الثابتة معناها إن العناصر متحدة كيميائيًا، مش إن ذرات بتحل مكان ذرات.","feedback":"الفكرة الغلط: إن أي alloy من عنصرين يبقى substitutional."},"d":{"why":"كل واحد فيهم ليه formula بنسبة ثابتة، والخليط الفيزيائي مالوش formula ثابتة.","feedback":"الفكرة الغلط: إن الـ intermetallic alloys خليط فيزيائي."}},"explanation":"الاتنين intermetallic alloys. العناصر اللي فيهم بتتحد كيميائيًا وبتكوّن chemical compound. والـ formulas بتاعتهم، $\\ce{Fe3C}$ و$\\ce{Au2Pb}$، مش ماشية على الـ valence law. الـ steel برضه iron مع carbon، لكن هناك ذرات الـ carbon يدوب قاعدة في الفراغات. عشان كده الـ steel نوعه interstitial، إنما الـ cementite نوعه intermetallic."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":18,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.definition-preparation-2","kind":"question","version":1,"ord":429,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.definition-preparation","concepts":[{"concept_id":"alloy.definition-preparation","role":"primary"}],"title":"chem-s3-en.question-alloy.definition-preparation-2","payload":{"stem":"Which of the following processes prepares an alloy?","tags":["exam-style","choose","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"A current passes through one solution of copper ions and tin ions, and both metals deposit on a plate at the same time.","correct":true},{"id":"b","text":"A current deposits copper on a plate from a solution of copper ions. Then the plate is moved to a solution of tin ions, and tin deposits on top.","correct":false},{"id":"c","text":"A current passes through a solution of tin ions only, and tin deposits on a copper plate.","correct":false},{"id":"d","text":"Copper powder and tin powder are shaken together in a bottle at room temperature.","correct":false}],"book_ref":"Ch.1 'ALLOYS' and 'Preparation of alloys', p.19","difficulty":4,"concept_ids":["alloy.definition-preparation"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: this is electro-deposition. Copper and tin deposit at the same time from one solution of their ions, so they form an alloy."},"b":{"why":"The two metals deposit one after the other as two separate layers, not at the same time, so they do not form an alloy.","feedback":"Misconception: Two coats made one after the other form an alloy."},"c":{"why":"The coat forms from the ions in the solution, and this solution supplies tin only, so the plate gets a tin coat, not an alloy.","feedback":"Misconception: The object's metal joins the coat to make an alloy."},"d":{"why":"Nothing is melted and no current is used, so neither of the book's two methods, melting or electro-deposition, is applied.","feedback":"Misconception: Any mixing of two metals gives an alloy."}},"explanation":"The book gives two methods. By melting: the metals are melted together and left to cool gradually. By electro-deposition: two metals or more deposit at the same time from a solution of their ions. Only one solution holding both ions deposits copper and tin together. Two layers made one after the other do not give an alloy. One metal deposited on another does not either."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: ده الـ electro-deposition. الـ copper والـ tin بيترسّبوا في نفس الوقت من محلول واحد فيه الـ ions بتاعتهم، فبيكوّنوا alloy."},"b":{"why":"الاتنين metals بيترسّبوا واحد ورا التاني على هيئة طبقتين منفصلين، مش في نفس الوقت، فمش بيكوّنوا alloy.","feedback":"الفكرة الغلط: إن طبقتين اتعملوا واحدة ورا التانية بيكوّنوا alloy."},"c":{"why":"الطلاء بيتكوّن من الـ ions اللي في المحلول، والمحلول ده فيه ions الـ tin لوحده، فالـ plate بيتغطّى بطبقة tin، مش alloy.","feedback":"الفكرة الغلط: إن الـ metal بتاع الحاجة اللي بنطليها بيدخل مع الطلاء ويعمل alloy."},"d":{"why":"مفيش حاجة اتصهرت ومفيش current، يعني مفيش ولا طريقة من الطريقتين اللي في الكتاب، الـ melting أو الـ electro-deposition.","feedback":"الفكرة الغلط: إن أي خلط لاتنين metals بيدّي alloy."}},"explanation":"الكتاب بيدي طريقتين. الـ melting: الـ metals بتتصهر مع بعض وتتساب تبرد بالتدريج. الـ electro-deposition: اتنين metals أو أكتر بيترسّبوا في نفس الوقت من محلول فيه الـ ions بتاعتهم. عشان كده المحلول الواحد اللي فيه النوعين من الـ ions هو اللي بيرسّب الـ copper والـ tin مع بعض. أما طبقتين اتعملوا واحدة ورا التانية فمش بيدّوا alloy، ولا metal واحد اترسّب على metal تاني."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":19,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.preparation","section_title":"Preparation of alloys","section_path":["Transition Elements","Alloys","Preparation of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.interstitial-2","kind":"question","version":1,"ord":430,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.interstitial","concepts":[{"concept_id":"alloy.interstitial","role":"primary"}],"title":"chem-s3-en.question-alloy.interstitial-2","payload":{"stem":"Give reasons: Introducing atoms of an element with a small atomic size into the crystal lattice of a pure metal increases its hardness.","tags":["exam-style","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) In a pure metal, atoms are arranged in compact closed rows; on hammering, a layer of atoms can slip over the other layers. (2) The small atoms enter the spaces between the metal atoms. (3) They prevent the movement of the metal layers, so the hardness increases (example: steel).","book_ref":"Ch.1 'Types of alloys', 1-Interstitial alloys, fig 1-5, p.19; exam form: give reasons","difficulty":3,"concept_ids":["alloy.interstitial"],"est_seconds":90},"layer":{"explanation":"A pure metal has its atoms in compact close rows. On hammering, one layer can slip over the others, so the metal is relatively soft. Small atoms sit in the spaces of the lattice. They block the layers from slipping, so the metal becomes harder. Key words: spaces of the crystal lattice, prevent the movement of the layers. Most likely wrong answer: 'the small atoms replace metal atoms'. They replace none; they fill the spaces."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ pure metal ذراته مترصوصة في صفوف متلاصقة. لما تطرقه، طبقة ممكن تنزلق فوق باقي الطبقات، فالـ metal بيبقى طري نسبيًا. الذرات الصغيرة بتقعد في فراغات الـ lattice وبتمنع الطبقات إنها تنزلق، فالـ metal بيبقى أصلب. الكلمات المفتاحية: spaces of the crystal lattice، prevent the movement of the layers. أكتر إجابة غلط بتتكتب: 'the small atoms replace metal atoms'. هي مش بتحل مكان ولا ذرة؛ هي بتملا الفراغات."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":20,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.substitutional-2","kind":"question","version":2,"ord":431,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.substitutional","concepts":[{"concept_id":"alloy.substitutional","role":"primary"},{"concept_id":"alloy.intermetallic","role":"secondary"},{"concept_id":"alloy.interstitial","role":"secondary"}],"title":"chem-s3-en.question-alloy.substitutional-2","payload":{"stem":"Classify the following alloys according to their type. (Atomic radius: Fe 1.16, Cr 1.17, Ni 1.15)","tags":["exam-style","classify"],"type":"classify","bloom":"remember","answer":{"im":["fe3c","au2pb"],"int":["steel"],"sub":["fecr","cuau","feni"]},"choices":[{"id":"fecr","text":"Ferrochrome (Fe-Cr) in stainless steel","misconception_id":"alloy.substitutional.mc2"},{"id":"cuau","text":"Copper-gold alloy"},{"id":"feni","text":"Ferronickel (Fe-Ni)"},{"id":"steel","text":"Steel (iron and carbon)","misconception_id":"alloy.interstitial.mc3"},{"id":"fe3c","text":"Cementite, $\\ce{Fe3C}$","misconception_id":"alloy.intermetallic.mc2"},{"id":"au2pb","text":"$\\ce{Au2Pb}$"}],"book_ref":"Ch.1 'Types of alloys', 2-Substitutional alloys, p.20; types of alloys, pp.19-20; exam form: classify","categories":[{"id":"sub","label":"Substitutional alloy"},{"id":"int","label":"Interstitial alloy"},{"id":"im","label":"Intermetallic alloy"}],"difficulty":2,"concept_ids":["alloy.substitutional","alloy.interstitial","alloy.intermetallic"],"est_seconds":75},"layer":{"choices":{"cuau":{"why":"There is no fixed formula here: copper and gold atoms take each other's places in the lattice.","feedback":"Misconception: Any alloy of two metals is intermetallic."},"fe3c":{"why":"It has a fixed formula, which shows that Fe and C are chemically combined into a compound.","feedback":"Misconception: Cementite is interstitial like steel."},"fecr":{"why":"The radii of Fe (1.16) and Cr (1.17) are nearly equal, so a Cr atom is too large for a small space between Fe atoms; it takes an Fe atom's place.","feedback":"Misconception: Fe-Cr is an interstitial alloy."},"feni":{"why":"Fe 1.16 and Ni 1.15 are nearly equal, so a Ni atom fits in an iron atom's place, not in a small space.","feedback":"Misconception: A slightly smaller atom goes into the spaces."},"au2pb":{"why":"Valency cannot explain this formula, which shows that Au and Pb combine chemically into a compound that disobeys the valence law.","feedback":"Misconception: Two metals always take each other's places."},"steel":{"why":"Carbon atoms are much smaller than iron atoms, so they sit in the spaces of the iron lattice.","feedback":"Misconception: Steel and cementite are the same alloy type."}},"explanation":"Substitutional: ferrochrome, copper-gold and ferronickel. Their atoms have nearly the same radius, crystal lattice and chemical properties. Interstitial: steel, where small carbon atoms sit in the spaces of the iron lattice. Intermetallic: cementite, $\\ce{Fe3C}$, and $\\ce{Au2Pb}$. Their elements combine chemically, and their formulas disobey the valence law. Common slip: putting steel and cementite together because both are Fe + C."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"cuau":{"why":"مفيش صيغة ثابتة هنا؛ ذرات الـ copper والـ gold بتاخد أماكن بعض.","feedback":"الفكرة الغلط: إن أي alloy من اتنين metals بيبقى intermetallic."},"fe3c":{"why":"ليه صيغة ثابتة، والصيغة الثابتة بتوضح إن الـ Fe والـ C متحدين كيميائيًا، مش مجرد ذرات في فراغات.","feedback":"الفكرة الغلط: إن الـ cementite نوعه interstitial زي الـ steel."},"fecr":{"why":"الـ radii بتاعة الـ Fe (1.16) والـ Cr (1.17) تقريبًا متساوية، فذرة الـ Cr ماتدخلش في فراغ صغير بين ذرات الـ Fe؛ هي بتاخد مكان ذرة Fe.","feedback":"الفكرة الغلط: إن الـ Fe-Cr ده interstitial alloy."},"feni":{"why":"الـ Fe 1.16 والـ Ni 1.15، تقريبًا نفس الحجم، فذرة الـ Ni بتاخد مكان ذرة Fe في الـ lattice.","feedback":"الفكرة الغلط: إن الذرة اللي أصغر بشوية بتدخل في الفراغات."},"au2pb":{"why":"الـ valency ماتقدرش تفسر الصيغة دي، وده معناه إن الـ Au والـ Pb متحدين كيميائيًا.","feedback":"الفكرة الغلط: إن أي اتنين metals دايمًا بياخدوا أماكن بعض."},"steel":{"why":"ذرات الـ carbon أصغر بكتير من ذرات الـ iron، فبتقعد في فراغات الـ lattice بتاع الـ iron.","feedback":"الفكرة الغلط: إن الـ steel والـ cementite نفس نوع الـ alloy."}},"explanation":"الـ Substitutional: الـ ferrochrome والـ copper-gold والـ ferronickel. ذراتهم ليها تقريبًا نفس الـ radius ونفس الـ crystal lattice ونفس الـ chemical properties. الـ Interstitial: الـ steel، اللي فيه ذرات الـ carbon الصغيرة بتقعد في فراغات الـ lattice بتاع الـ iron. الـ Intermetallic: الـ cementite، $\\ce{Fe3C}$، والـ $\\ce{Au2Pb}$. العناصر فيهم بتتحد كيميائيًا، والصيغ بتاعتهم مش ماشية على الـ valence law. غلطة بتتكرر: إنك تحط الـ steel والـ cementite مع بعض عشان الاتنين Fe + C."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":21,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.intermetallic-2","kind":"question","version":1,"ord":432,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.intermetallic","concepts":[{"concept_id":"alloy.intermetallic","role":"primary"}],"title":"chem-s3-en.question-alloy.intermetallic-2","payload":{"stem":"A made-up metal Q has valency 3 only. In an alloy, Q and carbon (valency 4) are found as the compound $\\ce{Q4C}$. What formula does the valence law predict for a compound of Q and carbon, and what type of alloy is this?","tags":["exam-style","two-step","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$\\ce{Q4C3}$; an intermetallic alloy","correct":true},{"id":"b","text":"$\\ce{Q3C4}$; an intermetallic alloy","correct":false},{"id":"c","text":"$\\ce{Q4C3}$; an interstitial alloy","correct":false},{"id":"d","text":"$\\ce{Q3C4}$; an interstitial alloy","correct":false}],"book_ref":"Ch.1 'Types of alloys', 3) Inter-metallic alloys, p.20","difficulty":4,"concept_ids":["alloy.intermetallic"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right: swapping the valencies of Q (3) and C (4) gives $\\ce{Q4C3}$. The real formula $\\ce{Q4C}$ disobeys the valence law, which is a sign of an intermetallic alloy."},"b":{"why":"In the swap method, each element takes the other's valency, so the subscript under Q is 4, not 3.","feedback":"Misconception: Each element keeps its own valency as its subscript."},"c":{"why":"Carbon atoms are small, but a fixed formula that disobeys the valence law shows a compound, not atoms that only sit in spaces.","feedback":"Misconception: Any alloy with carbon is interstitial."},"d":{"why":"Two slips: the subscript under Q is 4, not 3, and a real compound with a fixed formula shows an intermetallic alloy, not an interstitial one.","feedback":"Misconception: Each element keeps its own valency, and any carbon alloy is interstitial."}},"explanation":"Swap the valencies: Q (3) and C (4) give $\\ce{Q4C3}$. The real formula, $\\ce{Q4C}$, disobeys the valence law. Such a formula is a sign of an intermetallic alloy: the elements combine chemically into a compound. Cementite, $\\ce{Fe3C}$, is the book's example with carbon."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: لما تبدّل الـ valencies بتاعة Q (3) و C (4) هتطلع $\\ce{Q4C3}$. والـ formula الحقيقية $\\ce{Q4C}$ مش ماشية على الـ valence law، ودي علامة على intermetallic alloy."},"b":{"why":"في طريقة التبديل، كل عنصر بياخد الـ valency بتاعة التاني، فالرقم اللي تحت الـ Q هو 4 مش 3.","feedback":"الفكرة الغلط: إن كل عنصر بياخد الـ valency بتاعته هو كرقم تحتيه."},"c":{"why":"ذرات الـ carbon صغيرة، لكن formula ثابتة مش ماشية على الـ valence law بتدل على compound، مش على ذرات يدوب قاعدة في الفراغات.","feedback":"الفكرة الغلط: إن أي alloy فيه carbon يبقى interstitial."},"d":{"why":"هنا غلطتين: الرقم اللي تحت الـ Q هو 4 مش 3، والـ compound الحقيقي اللي ليه formula ثابتة بيدل على intermetallic alloy، مش interstitial.","feedback":"الفكرة الغلط: إن كل عنصر بياخد الـ valency بتاعته، وإن أي alloy فيه carbon يبقى interstitial."}},"explanation":"بدّل الـ valencies: Q (3) و C (4) يدّوا $\\ce{Q4C3}$. لكن الـ formula الحقيقية $\\ce{Q4C}$ مش ماشية على الـ valence law. والـ formula اللي زي دي علامة على intermetallic alloy: العناصر بتتحد كيميائيًا وبتكوّن compound. والـ cementite، $\\ce{Fe3C}$، هو مثال الكتاب اللي فيه carbon."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":22,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.definition-preparation-3","kind":"question","version":1,"ord":433,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.definition-preparation","concepts":[{"concept_id":"alloy.definition-preparation","role":"primary"},{"concept_id":"chem.electroplating-basic","role":"secondary"}],"title":"chem-s3-en.question-alloy.definition-preparation-3","payload":{"stem":"Iron handles are coated with an alloy X by electro-deposition, from one solution that contains copper ions and zinc ions. What is X, and to which terminal are the handles joined?","tags":["exam-style","two-step"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"X is brass; the handles are joined to the negative terminal.","correct":true},{"id":"b","text":"X is bronze; the handles are joined to the negative terminal.","correct":false},{"id":"c","text":"X is brass; the handles are joined to the positive terminal.","correct":false},{"id":"d","text":"X is bronze; the handles are joined to the positive terminal.","correct":false}],"book_ref":"Ch.1 'ALLOYS' and 'Preparation of alloys', p.19; bronze, p.8","difficulty":3,"concept_ids":["alloy.definition-preparation","chem.electroplating-basic"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: copper with zinc is brass. The handles take the negative terminal because copper ions and zinc ions are positive, so both deposit on them together."},"b":{"why":"Bronze is copper with tin, and this solution has no tin ions: it has copper ions and zinc ions.","feedback":"Misconception: Every copper alloy is bronze."},"c":{"why":"Copper ions and zinc ions are both positive, so they move to the negative terminal, not the positive one.","feedback":"Misconception: The object to be coated is the positive electrode."},"d":{"why":"Two slips here. Bronze is copper with tin, but this solution has copper ions and zinc ions. And positive ions move to the negative terminal, not the positive one.","feedback":"Misconception: Every copper alloy is bronze, and the object is the positive electrode."}},"explanation":"Brass is the alloy of copper and zinc (Cu + Zn). Bronze is copper with tin. The handles must receive both metals, so they are joined to the negative terminal. Copper ions and zinc ions are positive, so both move to the handles. They deposit there at the same time and form a brass coat."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ copper مع الـ zinc يبقى brass. والمقابض بتتوصّل بالـ negative terminal عشان الـ copper ions والـ zinc ions positive، فالاتنين بيترسّبوا عليها مع بعض."},"b":{"why":"الـ bronze فعلًا alloy للـ copper، لكن مع الـ tin. والمحلول ده فيه copper ions و zinc ions، ومفيهوش tin.","feedback":"الفكرة الغلط: إن أي alloy للـ copper يبقى bronze."},"c":{"why":"الـ copper ions والـ zinc ions الاتنين positive، والـ positive ions بتتشد للـ negative terminal، مش للـ positive.","feedback":"الفكرة الغلط: إن الحاجة اللي هنطليها هي الـ positive electrode."},"d":{"why":"هنا فيه غلطتين: المحلول فيه copper و zinc، مش tin، فالـ alloy مش bronze. والـ positive ions بتتشد للـ negative terminal، مش للـ positive.","feedback":"الفكرة الغلط: إن أي alloy للـ copper يبقى bronze، وإن الحاجة اللي هنطليها هي الـ positive electrode."}},"explanation":"الـ brass هو الـ alloy بتاع الـ copper والـ zinc (Cu + Zn). أما الـ bronze فهو copper مع tin. المقابض لازم تستقبل الـ metals الاتنين، فبتتوصّل بالـ negative terminal. الـ copper ions والـ zinc ions positive، فالاتنين بيتحركوا ناحية المقابض، وبيترسّبوا عليها في نفس الوقت ويكوّنوا طبقة brass."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":23,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.preparation","section_title":"Preparation of alloys","section_path":["Transition Elements","Alloys","Preparation of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"relation":"beyond"}]},{"id":"chem-s3-en.question-alloy.interstitial-3","kind":"question","version":1,"ord":434,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.interstitial","concepts":[{"concept_id":"alloy.interstitial","role":"primary"}],"title":"chem-s3-en.question-alloy.interstitial-3","payload":{"stem":"An engineer wants to harden a metal by putting atoms of another element into the spaces of its crystal lattice, without removing any of its own atoms. Which property must the added element have?","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Its atoms must be much smaller than the atoms of the metal.","correct":true},{"id":"b","text":"Its atoms must have the same atomic radius as the metal atoms.","correct":false},{"id":"c","text":"It must have the same crystal lattice and chemical properties as the metal.","correct":false},{"id":"d","text":"It must combine chemically with the metal to form a compound with a fixed formula.","correct":false,"misconception_id":"alloy.definition-preparation.mc2"}],"book_ref":"Ch.1 'Types of alloys', 1-Interstitial alloys, fig 1-5, p.19","difficulty":2,"concept_ids":["alloy.interstitial"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: the spaces between the metal atoms are small, so the added atoms must have a small atomic size to enter them. That gives an interstitial alloy."},"b":{"why":"Atoms of the same size need a whole atom's place, so they would not fit in the small spaces.","feedback":"Misconception: Atoms of the same size enter the spaces."},"c":{"why":"Those are conditions for atoms that take the metal atoms' places. The engineer wants to add atoms without removing any.","feedback":"Misconception: Interstitial and substitutional conditions are the same."},"d":{"why":"A compound forms in a different alloy type. Here the atoms only sit in the spaces, and that needs a small atomic size.","feedback":"Misconception: Every alloy is a chemical compound."}},"explanation":"The spaces between metal atoms are small. Only atoms of an element with a small atomic size can enter them. This gives an interstitial alloy, such as steel (carbon in iron). Same-size atoms with the same lattice and chemical properties give a substitutional alloy. Chemical combination gives an intermetallic alloy."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الفراغات اللي بين ذرات الـ metal صغيرة، فالذرات المضافة لازم يبقى الـ atomic size بتاعها صغير عشان تدخلها. وده بيدّي interstitial alloy."},"b":{"why":"الذرات اللي في نفس الحجم محتاجة مكان ذرة كاملة، فمش هتدخل في الفراغات الصغيرة.","feedback":"الفكرة الغلط: إن الذرات اللي في نفس الحجم بتدخل في الفراغات."},"c":{"why":"دي شروط للذرات اللي بتاخد أماكن ذرات الـ metal، والمهندس عايز يحط ذرات في الفراغات من غير ما يشيل أي ذرة.","feedback":"الفكرة الغلط: إن شروط الـ interstitial هي نفسها شروط الـ substitutional."},"d":{"why":"الـ compound بيتكوّن في نوع تاني من الـ alloy. هنا الذرات مجرد بتقعد في الفراغات، واللي بيخليها تدخل فيها هو صغر حجمها.","feedback":"الفكرة الغلط: إن أي alloy يبقى chemical compound."}},"explanation":"الفراغات اللي بين ذرات الـ metal صغيرة، ومفيش غير ذرات عنصر الـ atomic size بتاعه صغير تقدر تدخلها. وده بيدّي interstitial alloy، زي الـ steel (carbon في iron). الذرات اللي في نفس الحجم ومعاها نفس الـ lattice ونفس الـ chemical properties بتدّي substitutional alloy. والاتحاد الكيميائي بيدّي intermetallic alloy."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":24,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.substitutional-3","kind":"question","version":1,"ord":435,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.substitutional","concepts":[{"concept_id":"alloy.substitutional","role":"primary"}],"title":"chem-s3-en.question-alloy.substitutional-3","payload":{"stem":"Consider the following statements about substitutional alloys: (I) Some atoms of the pure metal are replaced by atoms of another metal. (II) The added atoms must be much smaller than the atoms of the pure metal. (III) Ferrochrome in stainless steel is an example. Which statements are correct?","tags":["exam-style","correct-statements"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"(I) and (III) only","correct":true},{"id":"b","text":"(I) and (II) only","correct":false},{"id":"c","text":"(II) and (III) only","correct":false},{"id":"d","text":"(I), (II) and (III)","correct":false}],"book_ref":"Ch.1 'Types of alloys', 2-Substitutional alloys, p.20","difficulty":3,"concept_ids":["alloy.substitutional"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: (I) is the book's description of a substitutional alloy and (III) is a book example. (II) describes the small atoms of an interstitial alloy."},"b":{"why":"Statement (II) is wrong: a much smaller atom cannot fill a whole atom's place, it enters the spaces (interstitial). And (III) is correct: ferrochrome in stainless steel is a book example.","feedback":"Misconception: The replacing atoms must be smaller."},"c":{"why":"Statement (II) describes atoms that sit in the spaces, which is an interstitial alloy. And (I) is correct: it is the book's description of a substitutional alloy.","feedback":"Misconception: Substitutional alloys have small atoms in the spaces."},"d":{"why":"One statement belongs to another alloy type. The book says the atoms here have the same atomic radius, so (II), about much smaller atoms, is wrong.","feedback":"Misconception: Interstitial and substitutional conditions are the same."}},"explanation":"(I) is the book's description of a substitutional alloy. (III) is correct: ferrochrome in stainless steel is a book example. (II) is wrong: the atoms must have the same atomic radius, not a much smaller one. Much smaller atoms enter the spaces and form an interstitial alloy."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: (I) هي وصف الكتاب للـ substitutional alloy و(III) مثال من الكتاب. أما (II) فبتوصف الذرات الصغيرة بتاعة الـ interstitial alloy."},"b":{"why":"الجملة (II) غلط: الذرة الأصغر بكتير مش بتملا مكان ذرة كاملة، دي بتدخل في الفراغات (interstitial). و(III) صح: الـ ferrochrome في الـ stainless steel مثال من الكتاب.","feedback":"الفكرة الغلط: إن الذرات اللي بتحل المكان لازم تكون أصغر."},"c":{"why":"الجملة (II) بتوصف ذرات بتقعد في الفراغات، وده interstitial alloy. و(I) صح: دي وصف الكتاب للـ substitutional alloy.","feedback":"الفكرة الغلط: إن الـ substitutional alloys فيها ذرات صغيرة في الفراغات."},"d":{"why":"الجملة (II) تبع نوع alloy تاني: الكتاب بيقول إن الذرات هنا لازم يبقى ليها نفس الـ atomic radius، مش أصغر بكتير.","feedback":"الفكرة الغلط: إن شروط الـ interstitial والـ substitutional واحدة."}},"explanation":"(I) هي وصف الكتاب للـ substitutional alloy. (III) صح: الـ ferrochrome في الـ stainless steel مثال من الكتاب. (II) غلط: الذرات لازم يبقى ليها نفس الـ atomic radius، مش أصغر بكتير. الذرات الأصغر بكتير بتدخل في الفراغات وبتكوّن interstitial alloy."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":25,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.intermetallic-3","kind":"question","version":2,"ord":436,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.intermetallic","concepts":[{"concept_id":"alloy.intermetallic","role":"primary"},{"concept_id":"alloy.interstitial","role":"secondary"},{"concept_id":"alloy.substitutional","role":"secondary"}],"title":"chem-s3-en.question-alloy.intermetallic-3","payload":{"stem":"Compare the three types of alloys: classify each description under the type it describes.","tags":["exam-style","compare","classify"],"type":"classify","bloom":"understand","answer":{"im":["d5","d6","d7"],"int":["d1","d2"],"sub":["d3","d4"]},"choices":[{"id":"d1","text":"Atoms of an element with a small atomic size enter the spaces of the lattice.","misconception_id":"alloy.interstitial.mc1"},{"id":"d2","text":"Steel is the book's example."},{"id":"d3","text":"Some atoms of the pure metal are replaced by atoms of another metal."},{"id":"d4","text":"The metals have the same atomic radius, crystal lattice and chemical properties."},{"id":"d5","text":"The elements combine chemically to form a chemical compound.","misconception_id":"alloy.definition-preparation.mc2"},{"id":"d6","text":"The chemical formula disobeys the valence law."},{"id":"d7","text":"The metals are not in the same group of the periodic table."}],"book_ref":"Ch.1 'Types of alloys' 1-3, pp.19-20; exam form: compare","categories":[{"id":"int","label":"Interstitial alloy"},{"id":"sub","label":"Substitutional alloy"},{"id":"im","label":"Intermetallic alloy"}],"difficulty":3,"concept_ids":["alloy.intermetallic","alloy.interstitial","alloy.substitutional"],"est_seconds":120},"layer":{"choices":{"d1":{"why":"These small atoms sit between the metal atoms, in the spaces; they do not take an atom's place.","feedback":"Misconception: Small atoms replace the host atoms."},"d2":{"why":"Steel is iron with carbon. Carbon atoms are much smaller than iron atoms, and steel has no fixed formula: the carbon only sits in the spaces.","feedback":"Misconception: Steel is intermetallic like cementite."},"d3":{"why":"Atoms leave their places here, and another metal's atoms of the same size fill those places. Much smaller atoms would only fit in the spaces.","feedback":"Misconception: Replacement happens in the alloy with small atoms."},"d4":{"why":"The atoms need the same size, lattice and chemical properties so that they can take each other's places in the lattice.","feedback":"Misconception: Same-size atoms combine into a compound."},"d5":{"why":"Nothing is chemically combined when atoms only fill spaces or swap places. A compound forms in a different alloy type.","feedback":"Misconception: Every alloy is a chemical compound."},"d6":{"why":"Only a compound has a chemical formula, and the elements form a compound only when they combine chemically.","feedback":"Misconception: Any alloy has a formula that obeys valency."},"d7":{"why":"Duralumin, aluminum with copper, is the book's example here: its elements combine chemically into a compound.","feedback":"Misconception: The group of the metals decides interstitial alloys."}},"explanation":"Interstitial: atoms with a small atomic size enter the spaces of the lattice; steel is the example. Substitutional: atoms of another metal replace some atoms of the pure metal. They need the same atomic radius, crystal lattice and chemical properties. Intermetallic: the elements combine chemically into a compound. Its formula disobeys the valence law, and the metals are not in the same group."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"d1":{"why":"الذرات الصغيرة دي مش بتاخد مكان ذرة؛ هي بتقعد في الفراغات اللي بين الذرات.","feedback":"الفكرة الغلط: إن الذرات الصغيرة بتحل مكان ذرات الـ metal الأساسي."},"d2":{"why":"الـ steel هو iron مع carbon. والـ carbon أصغر بكتير من الـ iron، فبيقعد في الفراغات، والـ steel مالوش صيغة ثابتة.","feedback":"الفكرة الغلط: إن الـ steel نوعه intermetallic زي الـ cementite."},"d3":{"why":"هنا ذرات بتسيب أماكنها لذرات metal تاني. والذرات الأصغر بكتير ماتقدرش تملا الأماكن دي؛ دي بتقعد في الفراغات.","feedback":"الفكرة الغلط: إن الإحلال بيحصل في الـ alloy اللي فيه ذرات صغيرة."},"d4":{"why":"الذرات محتاجة نفس الحجم ونفس الـ lattice عشان تقدر تحل مكان بعض في الـ lattice.","feedback":"الفكرة الغلط: إن الذرات اللي في نفس الحجم بتتحد وتكوّن compound."},"d5":{"why":"مفيش اتحاد كيميائي لما الذرات مجرد بتملا فراغات أو بتبدّل أماكن. الاتحاد الكيميائي بيكوّن compound.","feedback":"الفكرة الغلط: إن أي alloy يبقى chemical compound."},"d6":{"why":"الـ chemical formula بتبقى للـ compound، والـ compound بيتكوّن في الـ alloy اللي عناصره بتتحد كيميائيًا.","feedback":"الفكرة الغلط: إن أي alloy ليه صيغة ماشية على الـ valency."},"d7":{"why":"زي الـ duralumin: aluminum مع copper، metals مش في نفس الـ group، والعناصر فيه متحدة كيميائيًا.","feedback":"الفكرة الغلط: إن الـ group بتاع الـ metals هو اللي بيحدد الـ interstitial alloys."}},"explanation":"الـ Interstitial: ذرات عنصر الـ atomic size بتاعه صغير بتدخل في فراغات الـ lattice، ومثاله الـ steel. الـ Substitutional: ذرات metal تاني بتحل مكان بعض ذرات الـ metal النقي، وده محتاج نفس الـ atomic radius ونفس الـ crystal lattice ونفس الـ chemical properties. الـ Intermetallic: العناصر بتتحد كيميائيًا وتكوّن compound، والصيغة بتاعته مش ماشية على الـ valence law، والـ metals مش في نفس الـ group."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":26,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.interstitial-4","kind":"question","version":1,"ord":437,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.interstitial","concepts":[{"concept_id":"alloy.interstitial","role":"primary"}],"title":"chem-s3-en.question-alloy.interstitial-4","payload":{"stem":"Write the scientific term: An alloy formed by introducing atoms of an element with a small atomic size into the spaces of the crystal lattice of a pure metal.","tags":["exam-style","scientific-term"],"type":"short","bloom":"remember","answer":"Interstitial alloy (example: steel, iron and carbon).","book_ref":"Ch.1 'Types of alloys', 1-Interstitial alloys, fig 1-5, p.19; exam form: scientific term","difficulty":2,"concept_ids":["alloy.interstitial"],"est_seconds":30},"layer":{"explanation":"In an interstitial alloy, small atoms fill the spaces between the metal atoms. They prevent the layers from slipping, so the hardness increases. Steel, iron with carbon, is the book's example. Common slip: 'substitutional alloy'. There, atoms of another metal replace some atoms of the pure metal."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"في الـ interstitial alloy، ذرات صغيرة بتملا الفراغات اللي بين ذرات الـ metal، وبتمنع الطبقات إنها تنزلق، فالـ hardness بتزيد. ومثال الكتاب هو الـ steel: iron مع carbon. غلطة بتتكرر: إنك تكتب 'substitutional alloy'. هناك ذرات metal تاني بتحل مكان بعض ذرات الـ metal النقي."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":27,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.substitutional-4","kind":"question","version":1,"ord":438,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.substitutional","concepts":[{"concept_id":"alloy.substitutional","role":"primary"},{"concept_id":"te.atomic-radius","role":"secondary"}],"title":"chem-s3-en.question-alloy.substitutional-4","payload":{"stem":"The book's table (for illustration only) gives these atomic radii: Sc 1.44, Ti 1.32, Fe 1.16, Ni 1.15. Consider the atomic radius only. Which metal is most likely to replace some iron atoms, and what type of alloy does it form with iron?","tags":["exam-style","two-step","data"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Ni; a substitutional alloy","correct":true},{"id":"b","text":"Ni; an interstitial alloy","correct":false},{"id":"c","text":"Sc; a substitutional alloy","correct":false},{"id":"d","text":"Ti; an interstitial alloy","correct":false}],"book_ref":"Ch.1 'Types of alloys', 2-Substitutional alloys, p.20; atomic radius table, p.12","difficulty":4,"concept_ids":["alloy.substitutional","te.atomic-radius"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right: Ni (1.15) and Fe (1.16) have nearly the same atomic radius, so Ni atoms can take the places of some Fe atoms: a substitutional alloy, like the book's ferronickel."},"b":{"why":"Ni is only 0.01 smaller than Fe, far too large to fit in the spaces. Atoms that size take an iron atom's place.","feedback":"Misconception: A slightly smaller atom goes into the spaces."},"c":{"why":"Sc (1.44) is much larger than Fe (1.16), so a Sc atom would not fit in an iron atom's place.","feedback":"Misconception: Any transition metal can replace iron atoms."},"d":{"why":"The spaces are much smaller than an iron atom, and a Ti atom is larger than Fe, so it cannot fit there.","feedback":"Misconception: Any atom can enter the spaces between iron atoms."}},"explanation":"A substitutional alloy needs the same atomic radius (and the same crystal lattice and chemical properties). Ni (1.15) and Fe (1.16) are nearly equal, so Ni atoms can take the places of some Fe atoms. Ferronickel is the book's example. Sc and Ti atoms are much larger than Fe atoms. Only atoms much smaller than Fe can enter the spaces."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ Ni (1.15) والـ Fe (1.16) الـ atomic radius بتاعهم تقريبًا واحد، فذرات الـ Ni تقدر تاخد أماكن بعض ذرات الـ Fe: يعني substitutional alloy، زي الـ ferronickel اللي في الكتاب."},"b":{"why":"الـ Ni أصغر من الـ Fe بـ 0.01 يدوب، وده مش صغير كفاية إنه يدخل في الفراغات.","feedback":"الفكرة الغلط: إن الذرة اللي أصغر بشوية بتدخل في الفراغات."},"c":{"why":"الـ Sc (1.44) أكبر بكتير من الـ Fe (1.16)، فذرة الـ Sc مش هتدخل مكان ذرة iron.","feedback":"الفكرة الغلط: إن أي transition metal يقدر يحل مكان ذرات الـ iron."},"d":{"why":"الفراغات أصغر بكتير من ذرة الـ iron، وذرة الـ Ti أكبر من الـ Fe، فماتقدرش تدخل هناك.","feedback":"الفكرة الغلط: إن أي ذرة تقدر تدخل في الفراغات اللي بين ذرات الـ iron."}},"explanation":"الـ substitutional alloy محتاج نفس الـ atomic radius (ونفس الـ crystal lattice ونفس الـ chemical properties). الـ Ni (1.15) والـ Fe (1.16) تقريبًا متساويين، فذرات الـ Ni تقدر تاخد أماكن بعض ذرات الـ Fe. والـ Ferronickel هو مثال الكتاب. ذرات الـ Sc والـ Ti أكبر بكتير من ذرات الـ Fe. والذرات اللي أصغر بكتير من الـ Fe هي لوحدها اللي تقدر تدخل في الفراغات."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":28,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.intermetallic-4","kind":"question","version":1,"ord":439,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"alloy.intermetallic","concepts":[{"concept_id":"alloy.intermetallic","role":"primary"}],"title":"chem-s3-en.question-alloy.intermetallic-4","payload":{"stem":"Duralumin alloys are formed from aluminum with nickel, or aluminum with copper. Which choice gives their type and a correct statement about them?","tags":["exam-style","two-step"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Intermetallic; the elements combine chemically, and the formula disobeys the valence law.","correct":true},{"id":"b","text":"Substitutional; Al and Cu atoms take each other's places because they are in the same group.","correct":false},{"id":"c","text":"Intermetallic; the elements combine chemically, and the formula obeys the valence law like any compound.","correct":false},{"id":"d","text":"Interstitial; aluminum atoms enter the spaces of the copper lattice.","correct":false}],"book_ref":"Ch.1 'Types of alloys', 3) Inter-metallic alloys, p.20","difficulty":3,"concept_ids":["alloy.intermetallic"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: the book lists duralumin (Al-Ni, Al-Cu) as intermetallic. The elements combine chemically into a compound whose formula disobeys the valence law."},"b":{"why":"Al and Cu are not in the same group: aluminum is a main-group metal and copper is a transition metal. The book lists duralumin as a compound of its elements.","feedback":"Misconception: Duralumin is substitutional."},"c":{"why":"A compound, yes. But valency cannot explain formulas like $\\ce{Au2Pb}$ or $\\ce{Fe3C}$: the formula disobeys the valence law.","feedback":"Misconception: Every compound obeys the valence law."},"d":{"why":"Interstitial alloys need atoms much smaller than the host, and aluminum atoms are not that small.","feedback":"Misconception: Duralumin is interstitial."}},"explanation":"The book calls the Al-Ni and Al-Cu alloys duralumin and lists them as intermetallic alloys. The elements combine chemically to form a compound. Its formula disobeys the valence law. The metals are not in the same group: aluminum is a main-group metal, while nickel and copper are transition metals."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الكتاب بيحط الـ duralumin (Al-Ni و Al-Cu) مع الـ intermetallic alloys. العناصر بتتحد كيميائيًا وتكوّن compound والـ formula بتاعته مش ماشية على الـ valence law."},"b":{"why":"الـ Al والـ Cu مش في نفس الـ group في الـ periodic table. والكتاب بيقول إن الـ metals اللي في الـ duralumin بتتحد كيميائيًا.","feedback":"الفكرة الغلط: إن الـ duralumin نوعه substitutional."},"c":{"why":"هو compound فعلًا. لكن الـ valency ماتقدرش تفسّر formulas زي $\\ce{Au2Pb}$ أو $\\ce{Fe3C}$، فالـ formula مش ماشية على الـ valence law.","feedback":"الفكرة الغلط: إن أي compound لازم يمشي على الـ valence law."},"d":{"why":"الـ interstitial alloys محتاجة ذرات أصغر بكتير من ذرات الـ metal الأساسي، وذرات الـ aluminum مش صغيرة للدرجة دي.","feedback":"الفكرة الغلط: إن الـ duralumin نوعه interstitial."}},"explanation":"الكتاب بيسمّي الـ alloys بتاعة Al-Ni و Al-Cu باسم duralumin، وبيحطها مع الـ intermetallic alloys. العناصر فيها بتتحد كيميائيًا وبتكوّن compound، والـ formula بتاعته مش ماشية على الـ valence law. والـ metals مش في نفس الـ group: الـ aluminum ده main-group metal، إنما الـ nickel والـ copper دول transition metals."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":29,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.atomic-radius-6","kind":"question","version":1,"ord":440,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"te.atomic-radius","concepts":[{"concept_id":"te.atomic-radius","role":"primary"},{"concept_id":"alloy.substitutional","role":"secondary"}],"title":"chem-s3-en.question-te.atomic-radius-6","payload":{"stem":"Cobalt (atomic radius 1.16) and nickel (atomic radius 1.15) can form a substitutional alloy because their radii are almost equal. Which statement explains why the radius changes so little from Co to Ni?","tags":["mixed","retrieval","two-step"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"The increasing effective nuclear charge is nearly balanced by the increasing repulsion between 3d electrons.","correct":true},{"id":"b","text":"The effective nuclear charge stays the same from Co to Ni.","correct":false},{"id":"c","text":"Both atoms have the same number of 3d electrons.","correct":false},{"id":"d","text":"Nickel has five stable isotopes, which makes its atom larger than expected.","correct":false}],"book_ref":"Ch.1 atomic radius, pp.12-13; substitutional alloys, p.20","difficulty":3,"concept_ids":["te.atomic-radius","alloy.substitutional"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: from Co to Ni the effective nuclear charge rises, but so does the repulsion between the 3d electrons, so the radius barely changes."},"b":{"why":"Ni has one more proton than Co, so the pull of the nucleus increases.","feedback":"Misconception: The nuclear charge does not change across the series."},"c":{"why":"Co is [Ar] $4s^2\\,3d^7$ and Ni is [Ar] $4s^2\\,3d^8$, so Ni has one more 3d electron.","feedback":"Misconception: Neighbouring atoms have equal numbers of d electrons."},"d":{"why":"The isotopes explain an unusual atomic mass. Extra neutrons do not change the size of the electron cloud.","feedback":"Misconception: Isotopes change the atomic radius."}},"explanation":"Two opposite factors act from Cr to Cu. The effective nuclear charge increases, which pulls the electrons in and decreases the radius. The number of 3d electrons increases, so their repulsion increases, which increases the radius. The two nearly balance, so the radius is nearly constant. The book says this explains the use of these metals in making alloys."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: من الـ Co للـ Ni الـ effective nuclear charge بتزيد، لكن التنافر بين الـ 3d electrons بيزيد هو كمان، فالـ radius يدوب بيتغيّر."},"b":{"why":"الـ Ni عنده proton زيادة عن الـ Co، فشدّ الـ nucleus بيزيد.","feedback":"الفكرة الغلط: إن الـ nuclear charge مابتتغيّرش على طول السلسلة."},"c":{"why":"الـ Co هو [Ar] $4s^2\\,3d^7$ والـ Ni هو [Ar] $4s^2\\,3d^8$، يعني الـ Ni عنده 3d electron زيادة.","feedback":"الفكرة الغلط: إن الذرات اللي جنب بعض عندها نفس عدد الـ d electrons."},"d":{"why":"الـ isotopes بتفسّر atomic mass مش معتادة. الـ neutrons الزيادة مابتغيّرش حجم سحابة الـ electrons.","feedback":"الفكرة الغلط: إن الـ isotopes بتغيّر الـ atomic radius."}},"explanation":"فيه عاملين عكس بعض شغّالين من الـ Cr للـ Cu. الـ effective nuclear charge بتزيد، فبتشد الـ electrons لجوّه وبتصغّر الـ radius. وعدد الـ 3d electrons بيزيد، فالتنافر بينهم بيزيد وبيكبّر الـ radius. العاملين تقريبًا بيوازنوا بعض، فالـ radius ثابت تقريبًا. والكتاب بيقول إن ده بيفسّر استخدام الـ metals دي في عمل الـ alloys."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":41,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":13,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.blast-furnace-reduction-5","kind":"question","version":1,"ord":441,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"fe.blast-furnace-reduction","concepts":[{"concept_id":"fe.blast-furnace-reduction","role":"primary"}],"title":"chem-s3-en.question-fe.blast-furnace-reduction-5","payload":{"stem":"Explain the role of carbon monoxide in the blast furnace. Support your answer with an equation.","tags":["mixed","retrieval","explain-role"],"type":"short","bloom":"understand","answer":"Key points: (1) CO is the reducing agent: it reduces iron (III) oxide to iron. (2) $\\ce{3CO + Fe2O3 ->[\\text{higher than }700\\,^{\\circ}C] 2Fe + 3CO2}$. (3) CO gains oxygen and is oxidized to $\\ce{CO2}$. (4) CO comes from coke: $\\ce{C + O2 -> CO2}$, then $\\ce{CO2 + C -> 2CO}$.","book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (a), p.18; exam form: explain the role","difficulty":2,"concept_ids":["fe.blast-furnace-reduction"],"est_seconds":75},"layer":{"explanation":"In the blast furnace, coke burns to $\\ce{CO2}$, which meets hot coke and becomes CO. CO then takes oxygen from the iron ore. So CO is the reducing agent, and iron is set free above 700 °C. CO itself becomes $\\ce{CO2}$. Most likely wrong answer: 'CO only heats the furnace'. Its key role is reduction."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"في الـ blast furnace، الـ coke بيتحرق ويبقى $\\ce{CO2}$، والـ $\\ce{CO2}$ ده بيقابل coke سخن فيبقى CO. وبعدين الـ CO بياخد الـ oxygen من الـ iron ore. يبقى الـ CO هو الـ reducing agent، والـ iron بيتحرّر فوق 700 °C. والـ CO نفسه بيتحوّل لـ $\\ce{CO2}$. أشهر غلطة: 'الـ CO وظيفته إنه يسخّن الفرن وبس'. دوره الأساسي هو الـ reduction."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":62,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-mn-5","kind":"question","version":1,"ord":442,"group_id":"chem-s3-en.ch1.practice.alloys","primary_concept_id":"te.uses-mn","concepts":[{"concept_id":"te.uses-mn","role":"primary"},{"concept_id":"alloy.definition-preparation","role":"secondary"}],"title":"chem-s3-en.question-te.uses-mn-5","payload":{"stem":"Ferromanganese alloy is used in railway tracks. Which statement is correct?","tags":["mixed","retrieval","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"It is harder than steel, while pure manganese is not used because it is brittle.","correct":true},{"id":"b","text":"It is softer than steel, so the tracks bend without breaking.","correct":false},{"id":"c","text":"Pure manganese is used for tracks because it is harder than any of its alloys.","correct":false},{"id":"d","text":"It is an alloy of manganese with aluminum, used because it is light.","correct":false}],"book_ref":"Ch.1 uses of manganese, p.6; alloys, p.19","difficulty":2,"concept_ids":["te.uses-mn","alloy.definition-preparation"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Correct! The book uses ferromanganese in railway tracks because it is harder than steel, and pure manganese is not used because it is brittle."},"b":{"why":"A railway track needs to resist wear, not to bend, and ferromanganese is harder than steel, not softer.","feedback":"Misconception: Alloys are softer than steel."},"c":{"why":"The book says manganese as a pure metal is brittle, not tough, so it is not used pure.","feedback":"Misconception: Pure metals are better than their alloys."},"d":{"why":"'Ferro-' points to iron: ferromanganese is an alloy of iron and manganese. The Al-Mn alloy has a different use.","feedback":"Misconception: Ferromanganese is the Al-Mn alloy of cans."}},"explanation":"Ferromanganese is an alloy of iron and manganese. It is used in railway tracks because it is harder than steel. Manganese is not used as a pure metal because it is brittle. So it is always used as alloys or compounds. The aluminum-manganese alloy is used for soft drink cans because it resists corrosion."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الكتاب بيستخدم الـ ferromanganese في قضبان السكة الحديد لأنه أصلد من الـ steel، والـ manganese النقي مش بيُستخدم لأنه هش (brittle)."},"b":{"why":"قضبان السكة الحديد محتاجة تستحمل البَري، مش إنها تنثني، والـ ferromanganese أصلد من الـ steel، مش أطرى.","feedback":"الفكرة الغلط: إن الـ alloys أطرى من الـ steel."},"c":{"why":"الكتاب بيقول إن الـ manganese كـ metal نقي هش (brittle)، فمش بيُستخدم في القضبان.","feedback":"الفكرة الغلط: إن الـ metals النقية أحسن من الـ alloys بتاعتها."},"d":{"why":"الـ 'Ferro-' بتشاور على الـ iron، مش الـ aluminum. والـ Al-Mn alloy ليه استخدام تاني.","feedback":"الفكرة الغلط: إن الـ ferromanganese هو الـ Al-Mn alloy بتاع العلب."}},"explanation":"الـ ferromanganese هو alloy من الـ iron والـ manganese، وبيُستخدم في قضبان السكة الحديد لأنه أصلد من الـ steel. والـ manganese مش بيُستخدم كـ metal نقي لأنه هش (brittle)، فدايمًا بيُستخدم في alloys أو compounds. أما الـ aluminum-manganese alloy فبيُستخدم في علب المياه الغازية لأنه بيقاوم الـ corrosion."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":80,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys","section_title":"Alloys","section_path":["Transition Elements","Alloys"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.solution-concentration-1","kind":"question","version":1,"ord":461,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"chem.solution-concentration","concepts":[{"concept_id":"chem.solution-concentration","role":"primary"}],"title":"chem-s3-en.question-chem.solution-concentration-1","payload":{"stem":"Bottle A has 2 g of salt in 100 mL of solution. Bottle B has 20 g of the same salt in 100 mL of solution. Which statement is correct?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"B is more concentrated: it has more solute in the same volume.","correct":true},{"id":"b","text":"A is more concentrated: it has more water in it.","correct":false},{"id":"c","text":"They are equally concentrated: both have the same volume.","correct":false},{"id":"d","text":"They contain two different substances.","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 'with Acids', p.21: the (dil) and (conc.) labels","difficulty":1,"concept_ids":["chem.solution-concentration"],"est_seconds":40},"layer":{"choices":{"a":{"why":"Right: both bottles hold 100 mL, and B has 20 g of salt while A has 2 g, so B has more solute in the same volume."},"b":{"why":"Water is the solvent. More solvent with the same solute gives less solute in each mL, not more.","feedback":"Misconception: More water means more concentrated."},"c":{"why":"The volumes are equal, but the mass of salt differs: 2 g in A, 20 g in B.","feedback":"Misconception: Volume alone decides concentration."},"d":{"why":"The stem says the same salt. The amount of solute does not change what the substance is.","feedback":"Misconception: Dilute and concentrated solutions are different substances."}},"explanation":"Concentration compares the amount of solute in a given volume. Both bottles hold 100 mL. B holds 20 g of salt, and A only 2 g. So B is the concentrated one and A the dilute one. Both hold the same substance."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الإزازتين فيهم 100 mL، والإزازة B فيها 20 g من الـ salt والإزازة A فيها 2 g، يعني B فيها solute أكتر في نفس الحجم."},"b":{"why":"المية هنا هي الـ solvent. لما الـ solvent يزيد، كمية الـ solute في كل mL بتقل، مش بتزيد.","feedback":"الفكرة الغلط: إن المية الأكتر معناها إن الـ solution more concentrated."},"c":{"why":"الحجمين متساويين، لكن كمية الـ salt اللي في كل إزازة مختلفة.","feedback":"الفكرة الغلط: إن الحجم لوحده هو اللي بيحدد الـ concentration."},"d":{"why":"السؤال بيقول نفس الـ salt، وكمية الـ solute مابتغيّرش المادة نفسها.","feedback":"الفكرة الغلط: إن الـ dilute solution والـ concentrated solution مادتين مختلفتين."}},"explanation":"الـ concentration بيقارن كمية الـ solute في حجم معيّن. الإزازتين فيهم 100 mL. الإزازة B فيها 20 g من الـ salt، والإزازة A فيها يدوب 2 g. يبقى B هي الـ concentrated و A هي الـ dilute. والاتنين فيهم نفس المادة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":15,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-chem.solution-concentration-2","kind":"question","version":1,"ord":462,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"chem.solution-concentration","concepts":[{"concept_id":"chem.solution-concentration","role":"primary"}],"title":"chem-s3-en.question-chem.solution-concentration-2","payload":{"stem":"Solution P contains 12 g of a solute in 300 mL. Solution Q of the same solute has the same concentration, but its volume is only 50 mL. How many grams of solute does Q contain?","tags":["diagnostic","prerequisite","calculation"],"type":"numeric","bloom":"apply","answer":{"unit":"g","value":2,"tolerance":0.01},"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 'with Acids', p.21: the (dil) and (conc.) labels","difficulty":2,"concept_ids":["chem.solution-concentration"],"est_seconds":60},"layer":{"explanation":"The same concentration means the same mass of solute in each mL. P: 12 g ÷ 300 mL = 0.04 g in each mL. Q: 0.04 g × 50 mL = 2 g. Most likely wrong answer: 12 g. A smaller volume of the same solution holds less solute. Another slip: 72 g, from multiplying instead of dividing."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"نفس الـ concentration معناه نفس كتلة الـ solute في كل mL. في P: 12 g ÷ 300 mL = 0.04 g في كل mL. في Q: 0.04 g × 50 mL = 2 g. أشهر غلطة: إنك تقول 12 g. حجم أصغر من نفس الـ solution بيبقى فيه solute أقل. وغلطة تانية: 72 g، ودي بتيجي من إنك تضرب بدل ما تقسم."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":16,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-acid.metal-acid-reaction-1","kind":"question","version":2,"ord":463,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"acid.metal-acid-reaction","concepts":[{"concept_id":"acid.metal-acid-reaction","role":"primary"}],"title":"chem-s3-en.question-acid.metal-acid-reaction-1","payload":{"stem":"An active metal reacts with a dilute acid. What are the products?","tags":["diagnostic","prerequisite"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"A salt and hydrogen gas","correct":true},{"id":"b","text":"A salt and water","correct":false,"misconception_id":"acid.metal-acid-reaction.mc1"},{"id":"c","text":"A metal oxide and hydrogen gas","correct":false},{"id":"d","text":"A salt, water and carbon dioxide","correct":false,"misconception_id":"acid.metal-acid-reaction.mc3"}],"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 'with Acids', p.21: iron dissolves in dilute mineral acids","difficulty":1,"concept_ids":["acid.metal-acid-reaction"],"est_seconds":30},"layer":{"choices":{"a":{"why":"Right: an active metal takes the place of hydrogen in a dilute acid, so it forms a salt and hydrogen gas is given off."},"b":{"why":"Water forms when a metal oxide reacts with an acid. A metal itself gives hydrogen gas, which fizzes off.","feedback":"Misconception: Metal + dilute acid gives a salt and water."},"c":{"why":"The acid has no free oxygen to give. The metal joins the rest of the acid and forms a salt.","feedback":"Misconception: The metal forms an oxide in the acid."},"d":{"why":"Carbon dioxide forms with a carbonate. There is no carbon in a metal or in HCl.","feedback":"Misconception: The gas from a metal and an acid is carbon dioxide."}},"explanation":"Active metal + dilute acid → salt + hydrogen gas. The metal takes the place of the hydrogen in the acid. Example: $\\ce{Zn + 2HCl -> ZnCl2 + H2}$. A metal oxide gives a salt and water instead, with no gas."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ active metal بياخد مكان الـ hydrogen في الـ dilute acid، فبيتكوّن salt والـ hydrogen gas بيطلع."},"b":{"why":"الـ water بيتكوّن لما metal oxide يتفاعل مع acid. لكن لما الـ metal نفسه هو اللي يتفاعل، الـ gas اللي بيفوّر هو الـ hydrogen.","feedback":"الفكرة الغلط: إن الـ metal مع الـ dilute acid بيدّي salt و water."},"c":{"why":"الـ acid مفيهوش oxygen حر يدّيه، فمفيش oxide بيتكوّن. الـ metal بيكوّن salt مع باقي الـ acid.","feedback":"الفكرة الغلط: إن الـ metal بيكوّن oxide جوه الـ acid."},"d":{"why":"الـ carbon dioxide بيتكوّن مع carbonate. ومفيش أي carbon في الـ metal ولا في الـ HCl.","feedback":"الفكرة الغلط: إن الـ gas اللي بيطلع من metal مع acid هو carbon dioxide."}},"explanation":"القاعدة: active metal + dilute acid → salt + hydrogen gas. الـ metal بياخد مكان الـ hydrogen اللي في الـ acid. مثال: $\\ce{Zn + 2HCl -> ZnCl2 + H2}$. أما الـ metal oxide فبيدّي salt و water بدل كده، ومن غير أي gas."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":17,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"chem-s3-en.question-acid.metal-acid-reaction-2","kind":"question","version":2,"ord":464,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"acid.metal-acid-reaction","concepts":[{"concept_id":"acid.metal-acid-reaction","role":"primary"}],"title":"chem-s3-en.question-acid.metal-acid-reaction-2","payload":{"stem":"Which equation is correct for aluminum with dilute sulphuric acid? (Al is +3, $\\ce{SO4}$ is −2)","tags":["diagnostic","prerequisite","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$\\ce{2Al + 3H2SO4 -> Al2(SO4)3 + 3H2}$","correct":true},{"id":"b","text":"$\\ce{2Al + 3H2SO4 -> Al2(SO4)3 + 3H2O}$","correct":false,"misconception_id":"acid.metal-acid-reaction.mc1"},{"id":"c","text":"$\\ce{Al + H2SO4 -> AlSO4 + H2}$","correct":false},{"id":"d","text":"$\\ce{2Al + 3H2SO4 -> Al2(SO4)3 + 6H}$","correct":false}],"book_ref":"Prerequisite (preparatory chemistry); used in Ch.1 'with Acids', p.21: iron dissolves in dilute mineral acids","difficulty":2,"concept_ids":["acid.metal-acid-reaction"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: the salt $\\ce{Al2(SO4)3}$ has zero total charge, hydrogen leaves as $\\ce{H2}$ molecules, and the atoms balance (2 Al, 6 H, 3 S, 12 O on each side)."},"b":{"why":"A metal, not its oxide, reacts here. When a metal takes hydrogen's place, the hydrogen leaves as a gas, not as water.","feedback":"Misconception: Metal + dilute acid gives a salt and water."},"c":{"why":"Al is +3 and $\\ce{SO4}$ is −2, so the total charge of $\\ce{AlSO4}$ is not zero.","feedback":"Misconception: The salt's formula ignores valency."},"d":{"why":"Hydrogen gas is made of $\\ce{H2}$ molecules, each with two hydrogen atoms, so free H atoms are not given off.","feedback":"Misconception: Hydrogen leaves as single atoms."}},"explanation":"Active metal + dilute acid → salt + hydrogen gas. Al is +3 and sulphate is −2, so the salt is $\\ce{Al2(SO4)3}$. Two Al need three $\\ce{H2SO4}$. Their six H atoms leave as three $\\ce{H2}$ molecules. Check: 2 Al, 6 H, 3 S and 12 O on each side."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ salt $\\ce{Al2(SO4)3}$ مجموع الـ charge فيه صفر، والـ hydrogen بيطلع على شكل $\\ce{H2}$ molecules، والذرات متزنة (2 Al و6 H و3 S و12 O في كل ناحية)."},"b":{"why":"اللي بيتفاعل هنا metal، مش الـ oxide بتاعه. والـ metal لما ياخد مكان الـ hydrogen بيطلّع hydrogen gas، مش water.","feedback":"الفكرة الغلط: إن الـ metal مع الـ dilute acid بيدّي salt و water."},"c":{"why":"الـ Al هو +3 والـ $\\ce{SO4}$ هو −2، فمجموع الـ charge في $\\ce{AlSO4}$ مش بيساوي صفر، والصيغة دي غلط.","feedback":"الفكرة الغلط: إن الـ formula بتاعة الـ salt مش لازم تراعي الـ valency."},"d":{"why":"الـ hydrogen gas متكوّن من molecules، والـ hydrogen molecule بتتكتب $\\ce{H2}$، مش ذرات H منفصلة.","feedback":"الفكرة الغلط: إن الـ hydrogen بيطلع على شكل ذرات منفردة."}},"explanation":"القاعدة: active metal + dilute acid → salt + hydrogen gas. الـ Al هو +3 والـ sulphate هو −2، يبقى الـ salt هو $\\ce{Al2(SO4)3}$. اتنين Al محتاجين تلاتة $\\ce{H2SO4}$. وذرات الـ H الستة اللي فيهم بتطلع على شكل تلاتة $\\ce{H2}$ molecules. تشييك: 2 Al و6 H و3 S و12 O في كل ناحية."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":18,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":88,"page_to":88,"section_key":"ch4","section_title":"Electrochemistry","section_path":["Electrochemistry"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.physical-properties-1","kind":"question","version":2,"ord":465,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.physical-properties","concepts":[{"concept_id":"fe.physical-properties","role":"primary"}],"title":"chem-s3-en.question-fe.physical-properties-1","payload":{"stem":"Choose the correct answer: Pure iron is ...","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"relatively soft, malleable, ductile and magnetic, and it melts at 1538 °C","correct":true},{"id":"b","text":"very hard and brittle, magnetic, and it melts at 1538 °C","correct":false,"misconception_id":"fe.physical-properties.mc1"},{"id":"c","text":"relatively soft, malleable and ductile, but not magnetic","correct":false},{"id":"d","text":"very hard, so it is used in industry without adding other elements","correct":false,"misconception_id":"fe.physical-properties.mc2"}],"book_ref":"Ch.1 'Properties of Iron', p.20","difficulty":2,"concept_ids":["fe.physical-properties"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: the book describes pure iron as relatively soft, malleable, ductile and magnetic, melting at 1538 °C."},"b":{"why":"Pure iron is relatively soft, with low hardness, and malleable, not hard and brittle.","feedback":"Misconception: Pure iron is very hard."},"c":{"why":"Pure iron is magnetic: the book lists magnetic among its properties.","feedback":"Misconception: Pure iron is not magnetic."},"d":{"why":"Pure iron is relatively soft, so it has no industrial importance; that is why steels and iron alloys are made.","feedback":"Misconception: Pure iron is the most useful form of iron."}},"explanation":"The book describes pure iron as relatively soft, with low hardness, malleable, ductile and magnetic. It melts at 1538 °C, and its density is 7.87 g/cm³. Because it is relatively soft, pure iron has no industrial importance. Steels and iron alloys are used instead."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الكتاب بيوصف الـ iron النقي إنه relatively soft، و malleable و ductile و magnetic، وبينصهر عند 1538 °C."},"b":{"why":"الكتاب بيوصف الـ iron النقي إنه relatively soft و malleable، يعني بيتطرّق لشرايح، مش hard ولا brittle.","feedback":"الفكرة الغلط: إن الـ iron النقي very hard."},"c":{"why":"الـ iron والـ cobalt الاتنين بيستخدموا في عمل المغناطيسات، والكتاب بيوصف الـ iron النقي إنه magnetic.","feedback":"الفكرة الغلط: إن الـ iron النقي مش magnetic."},"d":{"why":"الـ iron النقي relatively soft، فمالوش أهمية صناعية، وعشان كده بيتعمل steels و iron alloys.","feedback":"الفكرة الغلط: إن الـ iron النقي هو أنفع شكل للـ iron."}},"explanation":"الكتاب بيوصف الـ iron النقي إنه relatively soft، يعني الـ hardness بتاعته قليلة، وكمان malleable و ductile و magnetic. بينصهر عند 1538 °C، والـ density بتاعته 7.87 g/cm³. وعشان هو relatively soft، الـ iron النقي مالوش أهمية صناعية، واللي بيتستخدم بداله هو الـ steels والـ iron alloys."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":19,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.properties","section_title":"Properties of Iron","section_path":["Transition Elements","Iron","Properties of Iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reactions-air-steam-1","kind":"question","version":1,"ord":466,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reactions-air-steam","concepts":[{"concept_id":"fe.reactions-air-steam","role":"primary"}],"title":"chem-s3-en.question-fe.reactions-air-steam-1","payload":{"stem":"Write the balanced equation for the reaction of red hot iron with water vapour, with the condition over the arrow and state symbols.","tags":["exam-style","equation"],"type":"short","bloom":"remember","answer":"\\ce{3Fe(s) + 4H2O(v) ->[500\\,^{\\circ}C] Fe3O4(s) + 4H2(g)}","book_ref":"Ch.1 'Chemical Properties' 1-2 (effect of air, effect of water vapour), p.21; exam form: write the equation","difficulty":3,"concept_ids":["fe.reactions-air-steam"],"est_seconds":75},"layer":{"explanation":"Red hot iron (500 °C) reacts with water vapour. The products are magnetic iron oxide and hydrogen gas. $\\ce{Fe3O4}$ needs 3 Fe and 4 O. Four $\\ce{H2O}$ supply the 4 O, and their 8 H atoms leave as four $\\ce{H2}$. Most likely wrong answers: $\\ce{Fe(OH)2}$ or $\\ce{Fe2O3}$ as the product. The book's product is $\\ce{Fe3O4}$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ iron وهو أحمر من السخونية (500 °C) بيتفاعل مع الـ water vapour. والنواتج هي الـ magnetic iron oxide والـ hydrogen gas. الـ $\\ce{Fe3O4}$ محتاج 3 Fe و4 O. أربعة $\\ce{H2O}$ بيجيبوا الـ 4 O، وذرات الـ H بتاعتهم الـ 8 بتطلع على هيئة أربعة $\\ce{H2}$. أشهر غلطة: إنك تكتب $\\ce{Fe(OH)2}$ أو $\\ce{Fe2O3}$ كناتج. الناتج في الكتاب هو $\\ce{Fe3O4}$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":20,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reactions-nonmetals-1","kind":"question","version":1,"ord":467,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reactions-nonmetals","concepts":[{"concept_id":"fe.reactions-nonmetals","role":"primary"}],"title":"chem-s3-en.question-fe.reactions-nonmetals-1","payload":{"stem":"Write the balanced equation for heating iron in chlorine gas, with state symbols.","tags":["exam-style","equation"],"type":"short","bloom":"remember","answer":"\\ce{2Fe(s) + 3Cl2(g) ->[\\Delta] 2FeCl3(s)}","book_ref":"Ch.1 'Chemical Properties' 3 (with non-metals), p.21; exam form: write the equation","difficulty":2,"concept_ids":["fe.reactions-nonmetals"],"est_seconds":60},"layer":{"explanation":"Iron reacts with chlorine to give iron (III) chloride, $\\ce{FeCl3}$. Chlorine is a strong oxidizing agent, so iron reaches +3. Balance Cl: 3 $\\ce{Cl2}$ give 6 Cl, enough for 2 $\\ce{FeCl3}$. Then write 2 Fe on the left. Most likely wrong answer: $\\ce{FeCl2}$. That is the product with dilute HCl, not with chlorine gas."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ iron بيتفاعل مع الـ chlorine ويدّي iron (III) chloride، $\\ce{FeCl3}$. الـ chlorine ده oxidizing agent قوي، فالـ iron بيوصل لـ +3. وازن الـ Cl الأول: 3 $\\ce{Cl2}$ فيهم 6 Cl، وده بالظبط اللي محتاجه 2 $\\ce{FeCl3}$. وبعدين اكتب 2 Fe في الشمال. أشهر غلطة: $\\ce{FeCl2}$. ده الناتج مع الـ dilute HCl، مش مع الـ chlorine gas."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":21,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reaction-dilute-acids-1","kind":"question","version":1,"ord":468,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reaction-dilute-acids","concepts":[{"concept_id":"fe.reaction-dilute-acids","role":"primary"}],"title":"chem-s3-en.question-fe.reaction-dilute-acids-1","payload":{"stem":"Give reasons: Iron reacts with dilute mineral acids to give iron (II) salts, not iron (III) salts.","tags":["exam-style","give-reasons","book-evaluation"],"type":"short","bloom":"understand","answer":"Key points: (1) Iron displaces hydrogen from the dilute acid: $\\ce{Fe + 2HCl -> FeCl2 + H2}$. (2) The hydrogen produced is a reducing agent. (3) It reduces iron (III) to iron (II), so iron (II) salts are obtained.","book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21; Evaluation Q7.7, p.27; exam form: give reasons","difficulty":2,"concept_ids":["fe.reaction-dilute-acids"],"est_seconds":60},"layer":{"explanation":"Iron dissolves in dilute mineral acids, and hydrogen gas forms. The book's reason: iron (III) salts are reduced by the produced hydrogen. So the products are iron (II) salts, like $\\ce{FeSO4}$ and $\\ce{FeCl2}$. Key words: reduced by the produced hydrogen. Most likely wrong answer: 'iron (III) is unstable'. In fact iron (III), $3d^5$, is the more stable state."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ iron بيدوب في الـ dilute mineral acids، وبيطلع hydrogen gas. وسبب الكتاب: الـ iron (III) salts بتتختزل بالـ hydrogen اللي بيطلع من التفاعل. فالنواتج بتبقى iron (II) salts، زي $\\ce{FeSO4}$ و$\\ce{FeCl2}$. الكلمات المفتاحية: reduced by the produced hydrogen. أشهر إجابة غلط: «الـ iron (III) مش مستقر». والحقيقة إن الـ iron (III)، $3d^5$، هو الحالة الأكثر استقرارًا."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":22,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"7","relation":"from_book"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reaction-conc-sulfuric-1","kind":"question","version":1,"ord":469,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reaction-conc-sulfuric","concepts":[{"concept_id":"fe.reaction-conc-sulfuric","role":"primary"}],"title":"chem-s3-en.question-fe.reaction-conc-sulfuric-1","payload":{"stem":"Write the balanced equation for the reaction of iron with hot concentrated sulphuric acid.","tags":["exam-style","equation"],"type":"short","bloom":"remember","answer":"\\ce{3Fe(s) + 8H2SO4(l) ->[\\text{conc.},\\ \\Delta] FeSO4(aq) + Fe2(SO4)3(aq) + 4SO2(g) + 8H2O(v)}","book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21; exam form: write the equation","difficulty":3,"concept_ids":["fe.reaction-conc-sulfuric"],"est_seconds":90},"layer":{"explanation":"Hot concentrated sulphuric acid gives iron (II) sulphate, iron (III) sulphate, sulphur dioxide and water. Check each side: 3 Fe, 8 S, 16 H and 32 O. Most likely wrong answer: $\\ce{Fe + H2SO4 -> FeSO4 + H2}$, the dilute-acid equation. No hydrogen forms here."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ hot concentrated sulphuric acid بيدّي الـ iron (II) sulphate والـ iron (III) sulphate والـ sulphur dioxide ومية. راجع كل ناحية: 3 Fe و8 S و16 H و32 O. أشهر غلطة: $\\ce{Fe + H2SO4 -> FeSO4 + H2}$، ودي معادلة الـ dilute acid. هنا مفيش hydrogen بيتكوّن."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":23,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.passivity-1","kind":"question","version":1,"ord":470,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.passivity","concepts":[{"concept_id":"fe.passivity","role":"primary"}],"title":"chem-s3-en.question-fe.passivity-1","payload":{"stem":"Give reasons: Concentrated nitric acid causes the passivity of iron.","tags":["exam-style","give-reasons","book-evaluation"],"type":"short","bloom":"understand","answer":"Key points: (1) Concentrated nitric acid forms a thin layer of oxide on the surface of iron. (2) This layer protects the metal from further reaction. (3) The layer can be removed by abrasion or by dilute hydrochloric acid.","book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21; Evaluation Q7.10, p.27; exam form: give reasons","difficulty":2,"concept_ids":["fe.passivity"],"est_seconds":60},"layer":{"explanation":"Concentrated nitric acid does not dissolve iron. It forms a thin layer of oxide on the surface. The layer covers the iron and protects it from further reaction. This state is called passivity. Key words: thin layer of oxide, protects the metal from further reaction. Most likely wrong answer: 'iron does not react with acids'. Iron dissolves easily in dilute acids."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ concentrated nitric acid مش بيدوّب الـ iron. هو بيكوّن طبقة رقيقة من الـ oxide على السطح. الطبقة دي بتغطي الـ iron وبتحميه من إنه يكمّل تفاعل، والحالة دي اسمها passivity. الكلمات المفتاحية اللي لازم تكتبها: thin layer of oxide، و protects the metal from further reaction. أشهر إجابة غلط: إن 'الـ iron مش بيتفاعل مع الـ acids'. لأ، الـ iron بيدوب بسهولة في الـ dilute acids."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":24,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":27,"page_to":27,"section_key":"ch1.eval.q7","section_title":"Give reasons for","section_path":["Transition Elements","Evaluation","Give reasons for"],"exercise":"Question 7","question":"10","relation":"from_book"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.physical-properties-2","kind":"question","version":1,"ord":471,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.physical-properties","concepts":[{"concept_id":"fe.physical-properties","role":"primary"}],"title":"chem-s3-en.question-fe.physical-properties-2","payload":{"stem":"Which of the following statements about iron are correct? Choose all that apply.","tags":["exam-style","correct-statements","multi"],"type":"multi","bloom":"understand","choices":[{"id":"s1","text":"Pure iron has no industrial importance because it is relatively soft.","correct":true},{"id":"s2","text":"The physical properties of iron depend on its purity and the nature of its impurities.","correct":true},{"id":"s3","text":"Many steels and iron alloys are produced with specific properties for many uses.","correct":true},{"id":"s4","text":"Pure iron is not attracted by a magnet.","correct":false},{"id":"s5","text":"The purer the iron, the harder it is.","correct":false},{"id":"s6","text":"Iron has a low melting point, so it is not used pure.","correct":false}],"book_ref":"Ch.1 'Properties of Iron', p.20","difficulty":3,"concept_ids":["fe.physical-properties"],"est_seconds":75},"layer":{"choices":{"s1":{"why":"Right: the book says pure iron has no industrial importance because it is relatively soft, with low hardness."},"s2":{"why":"Right: the book says iron's physical properties depend on its purity and the nature of its impurities."},"s3":{"why":"Right: because the properties depend on purity and impurities, many steels and iron alloys are produced with specific properties for many uses."},"s4":{"why":"The book's list of pure iron's properties includes magnetic, so pure iron is attracted by a magnet.","feedback":"Misconception: Pure iron is not magnetic."},"s5":{"why":"Pure iron is the relatively soft form of iron, so purity does not bring hardness.","feedback":"Misconception: Purity means hardness."},"s6":{"why":"1538 °C is a very high melting point. The book's reason for not using pure iron is that it is relatively soft.","feedback":"Misconception: Pure iron is not used because it melts easily."}},"explanation":"Pure iron is relatively soft, malleable, ductile and magnetic, and melts at 1538 °C. Being relatively soft, it has no industrial importance. Its physical properties depend on its purity and the nature of its impurities. So many steels and iron alloys are made for specific uses. Common slip: 'purer means harder'. Pure iron is the soft one."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"s1":{"why":"صح: الكتاب بيقول إن الـ iron النقي مالوش أهمية صناعية عشان هو relatively soft، والـ hardness بتاعته قليلة."},"s2":{"why":"صح: الكتاب بيقول إن الـ physical properties بتاعة الـ iron بتعتمد على درجة نقاوته ونوع الشوائب اللي فيه."},"s3":{"why":"صح: عشان الخواص بتعتمد على النقاوة والشوائب، بيتعمل steels و iron alloys كتير بخواص محددة لاستخدامات كتير."},"s4":{"why":"قايمة الكتاب للـ iron النقي فيها magnetic، فالـ iron النقي magnetic.","feedback":"الفكرة الغلط: إن الـ iron النقي مش magnetic."},"s5":{"why":"الـ iron النقي relatively soft، فالنقاوة مش معناها hardness؛ الأنقى مش أصلب.","feedback":"الفكرة الغلط: إن النقاوة معناها hardness."},"s6":{"why":"1538 °C دي درجة عالية جدًا. السبب اللي الكتاب بيقوله لعدم استخدام الـ iron النقي إنه relatively soft.","feedback":"الفكرة الغلط: إن الـ iron النقي مش بيتستخدم عشان بينصهر بسهولة."}},"explanation":"الـ iron النقي relatively soft، و malleable و ductile و magnetic، وبينصهر عند 1538 °C. وعشان هو relatively soft، مالوش أهمية صناعية. الـ physical properties بتاعته بتعتمد على درجة نقاوته ونوع الشوائب اللي فيه، وعشان كده بيتعمل steels و iron alloys كتير لاستخدامات محددة. غلطة بتتكرر: إنك تفتكر إن الأنقى يبقى أصلب. لأ، الـ iron النقي هو اللي soft."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":25,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.properties","section_title":"Properties of Iron","section_path":["Transition Elements","Iron","Properties of Iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reactions-air-steam-2","kind":"question","version":1,"ord":472,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reactions-air-steam","concepts":[{"concept_id":"fe.reactions-air-steam","role":"primary"}],"title":"chem-s3-en.question-fe.reactions-air-steam-2","payload":{"stem":"Red hot iron is heated in dry oxygen. Which statement about the solid product is correct?","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"It is $\\ce{Fe3O4}$, a black oxide attracted by a magnet.","correct":true},{"id":"b","text":"It is $\\ce{Fe2O3}$, a red oxide like hematite.","correct":false},{"id":"c","text":"It is FeO, because iron loses its two 4s electrons first.","correct":false},{"id":"d","text":"It is rust, a hydrated iron oxide.","correct":false}],"book_ref":"Ch.1 'Chemical Properties' 1-2 (effect of air, effect of water vapour), p.21","difficulty":2,"concept_ids":["fe.reactions-air-steam"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: red hot iron reacts with dry air or oxygen to give $\\ce{Fe3O4}$, magnetic iron oxide: black and attracted by a magnet."},"b":{"why":"Hematite is the best-known oxide. But the book's equation for red hot iron with dry air or oxygen gives a different oxide, not $\\ce{Fe2O3}$.","feedback":"Misconception: Heated iron + oxygen gives $\\ce{Fe2O3}$."},"c":{"why":"Iron does lose its 4s electrons first. But the product in the book's equation is not FeO: it does not hold iron (II) alone.","feedback":"Misconception: Iron forms only iron (II) when it first reacts."},"d":{"why":"Rust needs water, and dry oxygen contains none.","feedback":"Misconception: Heating iron in air is the same as rusting."}},"explanation":"Red hot iron reacts with dry air or oxygen to form magnetic iron oxide: $\\ce{3Fe + 2O2 ->[\\Delta] Fe3O4}$. It is black and attracted by a magnet. It is the same compound as magnetite. Rust needs water, and the oxygen here is dry."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ iron وهو أحمر من السخونية بيتفاعل مع الهوا الجاف أو الـ oxygen ويدّي $\\ce{Fe3O4}$، الـ magnetic iron oxide: لونه أسود وبيتجذب للمغناطيس."},"b":{"why":"الـ hematite هو أشهر oxide. لكن معادلة الكتاب للـ iron وهو أحمر من السخونية مع الهوا الجاف أو الـ oxygen بتدّي oxide تاني، مش $\\ce{Fe2O3}$.","feedback":"الفكرة الغلط: إن الـ iron لما يتسخّن مع الـ oxygen بيدّي $\\ce{Fe2O3}$."},"c":{"why":"فعلًا الـ iron بيخسر الـ 4s electrons بتوعه الأول. لكن الناتج في معادلة الكتاب مش FeO: مفيهوش iron (II) لوحده.","feedback":"الفكرة الغلط: إن الـ iron بيكوّن iron (II) لوحده أول ما يتفاعل."},"d":{"why":"الـ rust محتاج مية، والـ oxygen هنا جاف ومافيهوش مية.","feedback":"الفكرة الغلط: إن تسخين الـ iron في الهوا هو نفسه الـ rusting."}},"explanation":"الـ iron وهو أحمر من السخونية بيتفاعل مع الهوا الجاف أو الـ oxygen ويكوّن الـ magnetic iron oxide: $\\ce{3Fe + 2O2 ->[\\Delta] Fe3O4}$. لونه أسود وبيتجذب للمغناطيس. وهو نفس الـ compound بتاع الـ magnetite. أما الـ rust فمحتاج مية، والـ oxygen هنا جاف."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":26,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":24,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reactions-nonmetals-2","kind":"question","version":1,"ord":473,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reactions-nonmetals","concepts":[{"concept_id":"fe.reactions-nonmetals","role":"primary"}],"title":"chem-s3-en.question-fe.reactions-nonmetals-2","payload":{"stem":"Iron filings are heated with sulphur powder. Which choice gives the product and the reason for iron's oxidation state in it?","tags":["exam-style","choose","reason"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"FeS; sulphur is a weaker oxidizing agent than chlorine, so iron stops at +2.","correct":true},{"id":"b","text":"$\\ce{Fe2S3}$; iron (III) has a stable half-filled $3d^5$ sublevel.","correct":false},{"id":"c","text":"$\\ce{FeSO4}$; sulphur takes oxygen from the air during heating.","correct":false},{"id":"d","text":"FeS; hydrogen formed in the reaction reduces iron (III) to iron (II).","correct":false}],"book_ref":"Ch.1 'Chemical Properties' 3 (with non-metals), p.21; Evaluation Q1.1, p.25","difficulty":3,"concept_ids":["fe.reactions-nonmetals"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: the book's equation gives FeS. Sulphur is a weaker oxidizing agent than chlorine, so iron reaches +2, not +3."},"b":{"why":"If stability alone decided, iron would form iron (III) with every non-metal. The state iron reaches depends on how strong an oxidizing agent the non-metal is, not on the stable $3d^5$ alone.","feedback":"Misconception: Fe + S gives $\\ce{Fe2S3}$; iron always reaches its most stable state."},"c":{"why":"The book's equation has only iron and sulphur, with no oxygen, so no sulphate forms.","feedback":"Misconception: Fe + S gives $\\ce{FeSO4}$."},"d":{"why":"That reason fits iron with dilute acids. No hydrogen forms from iron and sulphur.","feedback":"Misconception: Borrowing the dilute-acid reason for every iron (II) product."}},"explanation":"Iron and sulphur give iron (II) sulphide: $\\ce{Fe + S ->[\\Delta] FeS}$. Sulphur is −2, so iron is +2. Sulphur is a weaker oxidizing agent than chlorine, so iron stops at +2. No oxygen reacts, so no sulphate forms. No hydrogen forms either."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: معادلة الكتاب بتدّي FeS. والـ sulphur oxidizing agent أضعف من الـ chlorine، فالـ iron بيوصل لـ +2 مش +3."},"b":{"why":"لو الـ stability لوحدها هي اللي بتحكم، كان الـ iron هيكوّن iron (III) مع أي non-metal. لكن الحالة اللي الـ iron بيوصلها بتعتمد على قوة الـ non-metal كـ oxidizing agent، مش على الـ $3d^5$ الـ stable لوحده.","feedback":"الفكرة الغلط: إن Fe + S بيدّي $\\ce{Fe2S3}$، وإن الـ iron دايمًا بيوصل لأكتر حالة stable عنده."},"c":{"why":"معادلة الكتاب فيها iron و sulphur وخلاص، ومفيش أي oxygen، فماينفعش يتكوّن sulphate.","feedback":"الفكرة الغلط: إن Fe + S بيدّي $\\ce{FeSO4}$."},"d":{"why":"السبب ده ينفع مع الـ iron والـ dilute acids، لكن الـ iron والـ sulphur مابيطلّعوش hydrogen.","feedback":"الفكرة الغلط: إنك تستلف سبب الـ dilute acid وتطبّقه على أي ناتج iron (II)."}},"explanation":"الـ iron والـ sulphur بيدّوا iron (II) sulphide: $\\ce{Fe + S ->[\\Delta] FeS}$. الـ sulphur هنا −2، يعني الـ iron +2. والـ sulphur oxidizing agent أضعف من الـ chlorine، فالـ iron بيقف عند +2. ومفيش oxygen بيتفاعل، فمفيش sulphate بيتكوّن. ولا فيه hydrogen بيتكوّن كمان."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":27,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"relation":"beyond"}]},{"id":"chem-s3-en.question-fe.reaction-dilute-acids-2","kind":"question","version":2,"ord":474,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reaction-dilute-acids","concepts":[{"concept_id":"fe.reaction-dilute-acids","role":"primary"}],"title":"chem-s3-en.question-fe.reaction-dilute-acids-2","payload":{"stem":"Write the balanced equation for the reaction of iron with dilute sulphuric acid, with state symbols.","tags":["exam-style","equation"],"type":"short","bloom":"remember","answer":"$\\ce{Fe(s) + H2SO4(aq) ->[(dil)] FeSO4(aq) + H2(g)}$","book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21; exam form: write the equation","difficulty":2,"concept_ids":["fe.reaction-dilute-acids"],"est_seconds":45},"layer":{"explanation":"Iron displaces hydrogen from the dilute acid. The salt is iron (II) sulphate, $\\ce{FeSO4}$, and hydrogen gas is given off. The produced hydrogen keeps iron at +2. Most likely wrong answer: $\\ce{Fe2(SO4)3}$ as the salt."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ iron بياخد مكان الـ hydrogen في الـ dilute acid. الـ salt اللي بيتكوّن هو iron (II) sulphate، $\\ce{FeSO4}$، وبيطلع hydrogen gas. والـ hydrogen اللي بيطلع ده هو اللي بيخلّي الـ iron يفضل عند +2. أشهر إجابة غلط: إنك تكتب $\\ce{Fe2(SO4)3}$ على إنه الـ salt."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":28,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reaction-conc-sulfuric-2","kind":"question","version":2,"ord":475,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reaction-conc-sulfuric","concepts":[{"concept_id":"fe.reaction-conc-sulfuric","role":"primary"}],"title":"chem-s3-en.question-fe.reaction-conc-sulfuric-2","payload":{"stem":"Iron reacts with hot concentrated sulphuric acid. Which statement about the products is correct?","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Two salts form, with iron in the +2 and +3 oxidation states, and the gas is sulphur dioxide.","correct":true},{"id":"b","text":"Only iron (III) sulphate forms, because the concentrated acid is stronger.","correct":false,"misconception_id":"fe.reaction-conc-sulfuric.mc2"},{"id":"c","text":"Iron (II) sulphate and hydrogen form, as with the dilute acid.","correct":false,"misconception_id":"fe.reaction-conc-sulfuric.mc1"},{"id":"d","text":"Iron (II) sulphate, iron (III) sulphate and hydrogen form.","correct":false}],"book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21","difficulty":3,"concept_ids":["fe.reaction-conc-sulfuric"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: the book's equation gives iron (II) sulphate and iron (III) sulphate, so iron is +2 and +3, and the gas is sulphur dioxide."},"b":{"why":"The book's equation has two iron salts, iron (II) sulphate and iron (III) sulphate, not one.","feedback":"Misconception: Only iron (III) sulphate forms."},"c":{"why":"That is true for the dilute acid. Hot concentrated $\\ce{H2SO4}$ acts as an oxidizing agent: it does not leave all the iron as iron (II), and it releases sulphur dioxide, not hydrogen.","feedback":"Misconception: Concentrated $\\ce{H2SO4}$ gives $\\ce{H2}$ like the dilute acid."},"d":{"why":"If hydrogen formed, it would reduce the iron (III) to iron (II). The gas that really forms is sulphur dioxide.","feedback":"Misconception: Hydrogen forms with both salts."}},"explanation":"The book's equation: $\\ce{3Fe + 8H2SO4 -> FeSO4 + Fe2(SO4)3 + 4SO2 + 8H2O}$. Iron (II) sulphate holds iron at +2. Iron (III) sulphate holds iron at +3. The gas is sulphur dioxide, not hydrogen. The acid's sulphur is reduced from +6 to +4."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: معادلة الكتاب بتدّي iron (II) sulphate و iron (III) sulphate، يعني الـ iron عند +2 و +3، والـ gas هو الـ sulphur dioxide."},"b":{"why":"معادلة الكتاب فيها 2 iron salts: iron (II) sulphate و iron (III) sulphate، مش واحد بس.","feedback":"الفكرة الغلط: إن الـ iron (III) sulphate لوحده هو اللي بيتكوّن."},"c":{"why":"ده صح في حالة الـ dilute acid. لكن الـ $\\ce{H2SO4}$ الساخن المركّز بيشتغل كـ oxidizing agent، فمش بيسيب الـ iron كله iron (II)، ومابيطلّعش hydrogen، بيطلّع sulphur dioxide.","feedback":"الفكرة الغلط: إن الـ $\\ce{H2SO4}$ المركّز بيدّي $\\ce{H2}$ زي الـ dilute acid."},"d":{"why":"لو الـ hydrogen اتكوّن كان هيختزل الـ iron (III)؛ والـ gas اللي بيتكوّن فعلًا هو الـ sulphur dioxide.","feedback":"الفكرة الغلط: إن الـ hydrogen بيتكوّن مع الـ salts الاتنين."}},"explanation":"معادلة الكتاب: $\\ce{3Fe + 8H2SO4 -> FeSO4 + Fe2(SO4)3 + 4SO2 + 8H2O}$. الـ iron (II) sulphate فيه الـ iron عند +2. والـ iron (III) sulphate فيه الـ iron عند +3. والـ gas هو الـ sulphur dioxide، مش الـ hydrogen. والـ sulphur بتاع الـ acid بيحصله reduction من +6 لـ +4."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":29,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.passivity-2","kind":"question","version":1,"ord":476,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.passivity","concepts":[{"concept_id":"fe.passivity","role":"primary"}],"title":"chem-s3-en.question-fe.passivity-2","payload":{"stem":"Write the scientific term: The state of iron when a thin layer of oxide, formed by concentrated nitric acid, protects it from further reaction.","tags":["exam-style","scientific-term"],"type":"short","bloom":"remember","answer":"Passivity (of iron).","book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21; exam form: scientific term","difficulty":2,"concept_ids":["fe.passivity"],"est_seconds":30},"layer":{"explanation":"Concentrated nitric acid forms a thin oxide layer on iron. The layer stops further reaction. This is passivity. It is not permanent: abrasion or dilute hydrochloric acid removes the layer. Common slip: 'rusting'. Rust needs water and air; the passive layer comes from concentrated nitric acid."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ concentrated nitric acid بيكوّن طبقة رقيقة من الـ oxide على الـ iron، والطبقة دي بتوقّف أي تفاعل بعد كده. ده اسمه passivity. وخلّي بالك إنها مش دايمة: الـ abrasion أو الـ dilute hydrochloric acid بيشيلوا الطبقة. غلطة بتتكرر: إنك تكتب 'rusting'. الصدأ محتاج مية وهوا، إنما طبقة الـ passivity جاية من الـ concentrated nitric acid."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":30,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.physical-properties-3","kind":"question","version":1,"ord":477,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.physical-properties","concepts":[{"concept_id":"fe.physical-properties","role":"primary"},{"concept_id":"alloy.interstitial","role":"secondary"}],"title":"chem-s3-en.question-fe.physical-properties-3","payload":{"stem":"The table shows tests on three iron samples. One of them is pure iron. Which sample is the pure iron, and why is it not used in industry?","tags":["exam-style","two-step","data"],"type":"mcq","bloom":"apply","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["A",60,"bends slightly"],["B",15,"bends easily"],["C",70,"hardly bends"]],"caption":"Made-up test results","headers":["Sample","Hardness (made-up units)","On hammering"]},"children":[]}}},"choices":[{"id":"a","text":"B; it is relatively soft, with low hardness.","correct":true},{"id":"b","text":"C; pure iron is the hardest form of iron.","correct":false},{"id":"c","text":"B; it is not magnetic, so it has no use.","correct":false},{"id":"d","text":"C; it is too hard to be shaped.","correct":false}],"book_ref":"Ch.1 'Properties of Iron', p.20","difficulty":3,"concept_ids":["fe.physical-properties","alloy.interstitial"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: sample B has the lowest hardness and bends easily, which fits pure iron; the book says pure iron has no industrial importance because it is relatively soft."},"b":{"why":"Adding other elements makes iron harder, as in steel, so the hardest sample is not the pure iron.","feedback":"Misconception: Pure iron is the hardest form of iron."},"c":{"why":"The book lists pure iron as magnetic, so this reason does not hold; the book's reason is its low hardness.","feedback":"Misconception: Pure iron is not magnetic."},"d":{"why":"Pure iron is malleable and bends easily, so it is not too hard to shape; the hardest sample contains other elements.","feedback":"Misconception: Pure iron is too hard to shape."}},"explanation":"Pure iron is relatively soft, with low hardness, so it bends easily. Sample B has the lowest hardness, so it is the pure iron. Samples A and C contain other elements, which make them harder. The book's reason: pure iron is relatively soft, so it has no industrial importance. Steels and iron alloys are used instead."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: العينة B الـ hardness بتاعتها أقل حاجة وبتتني بسهولة، وده بتاع الـ iron النقي؛ والكتاب بيقول إن الـ iron النقي مالوش أهمية صناعية عشان هو relatively soft."},"b":{"why":"إضافة عناصر تانية للـ iron بتخليه أصلب، زي الـ steel، فالـ iron النقي هو الأطرى مش الأصلب.","feedback":"الفكرة الغلط: إن الـ iron النقي هو أصلب نوع من الـ iron."},"c":{"why":"السبب ده غلط: الكتاب كاتب إن الـ iron النقي magnetic.","feedback":"الفكرة الغلط: إن الـ iron النقي مش magnetic."},"d":{"why":"الـ iron النقي malleable وسهل يتطرّق لشرايح، مش hard لدرجة إنه مايتشكلش.","feedback":"الفكرة الغلط: إن الـ iron النقي hard لدرجة إنه مايتشكلش."}},"explanation":"الـ iron النقي relatively soft، والـ hardness بتاعته قليلة، فبيتني بسهولة. العينة B هي اللي الـ hardness بتاعتها أقل حاجة، يبقى هي الـ iron النقي. العينتين A و C فيهم عناصر تانية بتخليهم أصلب. وسبب الكتاب: الـ iron النقي relatively soft، فمالوش أهمية صناعية، واللي بيتستخدم بداله هو الـ steels والـ iron alloys."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":31,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.properties","section_title":"Properties of Iron","section_path":["Transition Elements","Iron","Properties of Iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reactions-air-steam-3","kind":"question","version":1,"ord":478,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reactions-air-steam","concepts":[{"concept_id":"fe.reactions-air-steam","role":"primary"}],"title":"chem-s3-en.question-fe.reactions-air-steam-3","payload":{"stem":"What happens when 16.8 g of iron is heated until red hot in excess dry oxygen? Write the balanced equation, then calculate the mass of the product. (Fe = 56, O = 16)","tags":["exam-style","what-happens","calculation"],"type":"short","bloom":"apply","answer":"Key points: (1) Magnetic iron oxide forms: $\\ce{3Fe(s) + 2O2(g) ->[\\Delta] Fe3O4(s)}$. (2) Moles of Fe = 16.8 ÷ 56 = 0.3 mol. (3) 3 mol Fe give 1 mol $\\ce{Fe3O4}$, so 0.1 mol forms. (4) Molar mass of $\\ce{Fe3O4}$ = 3(56) + 4(16) = 232 g/mol, so the mass = 0.1 × 232 = 23.2 g.","book_ref":"Ch.1 'Chemical Properties' 1-2 (effect of air, effect of water vapour), p.21; exam form: what happens when","difficulty":4,"concept_ids":["fe.reactions-air-steam"],"est_seconds":150},"layer":{"explanation":"Red hot iron and dry oxygen give magnetic iron oxide, $\\ce{Fe3O4}$. 16.8 g of iron is 0.3 mol. The equation shows 3 mol Fe → 1 mol $\\ce{Fe3O4}$. So 0.1 mol of $\\ce{Fe3O4}$ forms, which is 23.2 g. The solid gains mass because oxygen joins the iron. Most likely wrong answer: 24.0 g, from assuming $\\ce{Fe2O3}$ forms."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ iron وهو أحمر من السخونية مع الـ oxygen الجاف بيدّوا الـ magnetic iron oxide، $\\ce{Fe3O4}$. الـ 16.8 g من الـ iron دول = 0.3 mol. المعادلة بتقول 3 mol Fe → 1 mol $\\ce{Fe3O4}$. يبقى اللي بيتكوّن 0.1 mol من الـ $\\ce{Fe3O4}$، يعني 23.2 g. والمادة الصلبة كتلتها بتزيد عشان الـ oxygen بيتحد مع الـ iron. أشهر غلطة: 24.0 g، ودي بتيجي من إنك تفترض إن اللي بيتكوّن $\\ce{Fe2O3}$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":32,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reactions-nonmetals-3","kind":"question","version":1,"ord":479,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reactions-nonmetals","concepts":[{"concept_id":"fe.reactions-nonmetals","role":"primary"}],"title":"chem-s3-en.question-fe.reactions-nonmetals-3","payload":{"stem":"Compare between the reaction of iron with chlorine and its reaction with sulphur, in terms of: the equation, the oxidation state of iron in the product, and the reason for the difference.","tags":["exam-style","compare"],"type":"short","bloom":"understand","answer":"Key points: (1) Chlorine: $\\ce{2Fe + 3Cl2 ->[\\Delta] 2FeCl3}$, iron (III) chloride, iron +3. (2) Sulphur: $\\ce{Fe + S ->[\\Delta] FeS}$, iron (II) sulphide, iron +2. (3) Chlorine is a stronger oxidizing agent than sulphur, so it oxidizes iron to +3; sulphur takes it only to +2.","book_ref":"Ch.1 'Chemical Properties' 3 (with non-metals), p.21; exam form: compare","difficulty":3,"concept_ids":["fe.reactions-nonmetals"],"est_seconds":120},"layer":{"explanation":"With chlorine, iron gives iron (III) chloride. Each Cl is −1, so iron is +3. With sulphur, iron gives iron (II) sulphide. Sulphur is −2, so iron is +2. Chlorine is the stronger oxidizing agent. It takes iron to +3, the stable half-filled $3d^5$ state. Most likely wrong answer: $\\ce{Fe2S3}$ for the sulphur reaction."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"مع الـ chlorine، الـ iron بيدّي iron (III) chloride. كل Cl شحنته −1، فالـ iron +3. ومع الـ sulphur، الـ iron بيدّي iron (II) sulphide. الـ sulphur −2، فالـ iron +2. الـ chlorine هو الـ oxidizing agent الأقوى، وبياخد الـ iron لـ +3، اللي هي الحالة الـ stable بالـ $3d^5$ الـ half-filled. أشهر غلطة: إنك تكتب $\\ce{Fe2S3}$ في تفاعل الـ sulphur."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":33,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"relation":"beyond"}]},{"id":"chem-s3-en.question-fe.reaction-dilute-acids-3","kind":"question","version":2,"ord":480,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reaction-dilute-acids","concepts":[{"concept_id":"fe.reaction-dilute-acids","role":"primary"}],"title":"chem-s3-en.question-fe.reaction-dilute-acids-3","payload":{"stem":"Iron filings are added to dilute hydrochloric acid, and the gas formed is collected. Which choice gives the salt in the solution and the gas collected?","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"$\\ce{FeCl2}$; hydrogen","correct":true},{"id":"b","text":"$\\ce{FeCl3}$; hydrogen","correct":false,"misconception_id":"fe.reaction-dilute-acids.mc1"},{"id":"c","text":"$\\ce{FeCl2}$; chlorine","correct":false},{"id":"d","text":"$\\ce{FeCl3}$; chlorine","correct":false}],"book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21","difficulty":2,"concept_ids":["fe.reaction-dilute-acids"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: iron displaces hydrogen from the dilute acid, giving iron (II) chloride and hydrogen gas: $\\ce{Fe + 2HCl -> FeCl2 + H2}$."},"b":{"why":"Chlorine gas gives iron (III) chloride, but the gas formed here is hydrogen, which reduces iron (III) to iron (II).","feedback":"Misconception: Fe + HCl gives $\\ce{FeCl3}$ because Fe + $\\ce{Cl2}$ does."},"c":{"why":"The metal takes the place of hydrogen in the acid, so hydrogen is set free; the chlorine stays in the salt.","feedback":"Misconception: The acid releases chlorine gas."},"d":{"why":"Two slips: iron replaces hydrogen in HCl, not chlorine, and that hydrogen reduces iron (III) to iron (II).","feedback":"Misconception: Iron reacts with HCl as it does with chlorine gas."}},"explanation":"Iron is above hydrogen, so it displaces hydrogen from the acid: $\\ce{Fe + 2HCl ->[(dil)] FeCl2 + H2}$. The salt is iron (II) chloride. Iron (III) is reduced by the produced hydrogen. The chlorine stays in the salt; no chlorine gas forms."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ iron بياخد مكان الـ hydrogen في الـ dilute acid، فبيتكوّن iron (II) chloride وبيطلع hydrogen gas: $\\ce{Fe + 2HCl -> FeCl2 + H2}$."},"b":{"why":"الـ chlorine gas هو اللي بيدي iron (III) chloride. الـ gas اللي بيتكوّن هنا هو الـ hydrogen، وده بيختزل الـ iron (III) لـ iron (II).","feedback":"الفكرة الغلط: إن Fe + HCl بيدي $\\ce{FeCl3}$ عشان Fe + $\\ce{Cl2}$ بيديه."},"c":{"why":"الـ metal بياخد مكان عنصر واحد في الـ acid، وهو الـ hydrogen؛ الـ chlorine بيفضل في الـ salt.","feedback":"الفكرة الغلط: إن الـ acid بيطلّع chlorine gas."},"d":{"why":"فيه غلطتين هنا: الـ iron بياخد مكان الـ hydrogen في الـ HCl، مش الـ chlorine، والـ hydrogen ده بيختزل الـ iron (III) لـ iron (II).","feedback":"الفكرة الغلط: إن الـ iron بيتفاعل مع الـ HCl زي ما بيتفاعل مع الـ chlorine gas."}},"explanation":"الـ iron فوق الـ hydrogen، فبياخد مكانه في الـ acid: $\\ce{Fe + 2HCl ->[(dil)] FeCl2 + H2}$. الـ salt هو iron (II) chloride. والـ iron (III) بيتختزل بالـ hydrogen اللي بيطلع من التفاعل. الـ chlorine بيفضل في الـ salt، ومفيش chlorine gas بيطلع."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":34,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reaction-conc-sulfuric-3","kind":"question","version":1,"ord":481,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reaction-conc-sulfuric","concepts":[{"concept_id":"fe.reaction-conc-sulfuric","role":"primary"},{"concept_id":"fe.reaction-dilute-acids","role":"secondary"}],"title":"chem-s3-en.question-fe.reaction-conc-sulfuric-3","payload":{"stem":"Compare between the action of dilute sulphuric acid and of hot concentrated sulphuric acid on iron, in terms of: the iron salt(s) formed and the gas given off.","tags":["exam-style","compare"],"type":"short","bloom":"understand","answer":"Key points: (1) Dilute: $\\ce{Fe + H2SO4 -> FeSO4 + H2}$; one salt, iron (II) sulphate; the gas is hydrogen. (2) Hot concentrated: $\\ce{3Fe + 8H2SO4 -> FeSO4 + Fe2(SO4)3 + 4SO2 + 8H2O}$; two salts, iron (II) and iron (III) sulphates; the gas is sulphur dioxide (with water vapour).","book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21; exam form: compare","difficulty":3,"concept_ids":["fe.reaction-conc-sulfuric","fe.reaction-dilute-acids"],"est_seconds":120},"layer":{"explanation":"With the dilute acid, iron displaces hydrogen. The hydrogen keeps iron at +2, so only iron (II) sulphate forms. With the hot concentrated acid, no hydrogen forms. The products are iron (II) sulphate, iron (III) sulphate, sulphur dioxide and water. Most likely wrong answer: hydrogen gas from the concentrated acid too."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"مع الـ dilute acid، الـ iron بيحل محل الـ hydrogen. والـ hydrogen بيخلّي الـ iron عند +2، فاللي بيتكوّن هو الـ iron (II) sulphate لوحده. أما مع الـ hot concentrated acid، فمفيش hydrogen بيتكوّن. والنواتج هي الـ iron (II) sulphate والـ iron (III) sulphate والـ sulphur dioxide ومية. أشهر غلطة: إنك تقول إن الـ concentrated acid كمان بيطلّع hydrogen gas."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":35,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.passivity-3","kind":"question","version":1,"ord":482,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.passivity","concepts":[{"concept_id":"fe.passivity","role":"primary"},{"concept_id":"fe.reaction-dilute-acids","role":"secondary"}],"title":"chem-s3-en.question-fe.passivity-3","payload":{"stem":"A passive iron sheet is put in dilute hydrochloric acid. After some time, bubbles of gas appear on it. Which explanation is correct?","tags":["exam-style","choose","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"The acid removes the oxide layer; then fresh iron reacts with the acid and gives hydrogen.","correct":true},{"id":"b","text":"The oxide layer itself reacts with the acid and gives hydrogen gas.","correct":false},{"id":"c","text":"The bubbles are oxygen, released as the oxide layer breaks down.","correct":false},{"id":"d","text":"Passivity is permanent, so the gas must come from the acid breaking down by itself.","correct":false,"misconception_id":"fe.passivity.mc2"}],"book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21","difficulty":3,"concept_ids":["fe.passivity","fe.reaction-dilute-acids"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: dilute hydrochloric acid removes the thin oxide layer, and the fresh iron under it reacts with the acid: $\\ce{Fe + 2HCl -> FeCl2 + H2}$."},"b":{"why":"A metal oxide gives a salt and water with an acid, not a gas. The gas comes from fresh iron reacting with the acid.","feedback":"Misconception: A metal oxide gives hydrogen with an acid."},"c":{"why":"An acid reacts with an oxide; it does not split it into oxygen. Only the fresh iron under the layer can set a gas free.","feedback":"Misconception: The oxide layer decomposes into oxygen."},"d":{"why":"Dilute HCl does not break down on its own, and passivity is not permanent: dilute hydrochloric acid or abrasion removes the passive layer.","feedback":"Misconception: Passivity is permanent."}},"explanation":"Passivity is not permanent. Dilute hydrochloric acid removes the thin oxide layer. Fresh iron is then exposed. Iron is above hydrogen, so it reacts with the acid: $\\ce{Fe + 2HCl -> FeCl2 + H2}$. The bubbles are hydrogen. Abrasion would also remove the layer."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ dilute hydrochloric acid بيشيل طبقة الـ oxide الرقيقة، والـ iron الجديد اللي تحتها بيتفاعل مع الـ acid: $\\ce{Fe + 2HCl -> FeCl2 + H2}$."},"b":{"why":"الـ metal oxide لما يتفاعل مع acid بيدّي salt ومية، مش غاز؛ الغاز جاي من الـ iron الجديد اللي بان تحت الطبقة.","feedback":"الفكرة الغلط: إن الـ metal oxide بيدّي hydrogen مع الـ acid."},"c":{"why":"الـ acid بيتفاعل مع الـ oxide، مش بيفصصه لـ oxygen. الغاز جاي من تفاعل الـ iron نفسه مع الـ acid.","feedback":"الفكرة الغلط: إن طبقة الـ oxide بتتكسّر وتطلّع oxygen."},"d":{"why":"الـ dilute HCl مش بيتكسّر لوحده. الكتاب قال إن طبقة الـ passivity بتتشال بالـ abrasion أو بالـ dilute hydrochloric acid.","feedback":"الفكرة الغلط: إن الـ passivity دايمة."}},"explanation":"الـ passivity مش دايمة. الـ dilute hydrochloric acid بيشيل طبقة الـ oxide الرقيقة، فالـ iron الجديد اللي تحتها بيبان. والـ iron فوق الـ hydrogen، فبيتفاعل مع الـ acid: $\\ce{Fe + 2HCl -> FeCl2 + H2}$. يعني الفقاقيع دي hydrogen. وعلى فكرة الـ abrasion كمان كانت هتشيل الطبقة."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":36,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reactions-air-steam-4","kind":"question","version":1,"ord":483,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reactions-air-steam","concepts":[{"concept_id":"fe.reactions-air-steam","role":"primary"}],"title":"chem-s3-en.question-fe.reactions-air-steam-4","payload":{"stem":"Which reactants and condition give both magnetic iron oxide and hydrogen gas?","tags":["exam-style","choose","conditions"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Red hot iron (500 °C) and water vapour","correct":true},{"id":"b","text":"Red hot iron and dry air","correct":false},{"id":"c","text":"Iron and dilute hydrochloric acid at room temperature","correct":false},{"id":"d","text":"Iron and liquid water at room temperature","correct":false}],"book_ref":"Ch.1 'Chemical Properties' 1-2 (effect of air, effect of water vapour), p.21","difficulty":3,"concept_ids":["fe.reactions-air-steam"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: at 500 °C, red hot iron and water vapour give both magnetic iron oxide and hydrogen gas."},"b":{"why":"Dry air reacts through its oxygen and has no hydrogen to release.","feedback":"Misconception: The reaction with air also gives hydrogen."},"c":{"why":"Hydrogen does form here, but an acid gives a salt, not an oxide.","feedback":"Misconception: Any reaction that gives hydrogen also gives the magnetic oxide."},"d":{"why":"Cold water reacts with iron only very slowly. The book writes 500 °C over the arrow, with the iron red hot and the water as vapour.","feedback":"Misconception: Iron gives the magnetic oxide with water without heating."}},"explanation":"Red hot iron (500 °C) reacts with water vapour: $\\ce{3Fe + 4H2O ->[500\\,^{\\circ}C] Fe3O4 + 4H2}$. Magnetic iron oxide and hydrogen gas form. With dry air, only $\\ce{Fe3O4}$ forms. With a dilute acid, an iron (II) salt and hydrogen form."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: عند 500 °C، الـ iron الأحمر من السخونية مع الـ water vapour بيدّي الـ magnetic iron oxide والـ hydrogen gas مع بعض."},"b":{"why":"الهوا الجاف بيتفاعل عن طريق الـ oxygen اللي فيه، ومفيش hydrogen يطلع منه.","feedback":"الفكرة الغلط: إن التفاعل مع الهوا كمان بيدّي hydrogen."},"c":{"why":"فعلًا الـ hydrogen بيتكوّن هنا، لكن الـ acid بيسيب iron (II) salt، مش oxide.","feedback":"الفكرة الغلط: إن أي تفاعل بيدّي hydrogen لازم يدّي معاه الـ magnetic oxide."},"d":{"why":"المية الباردة بتتفاعل مع الـ iron ببطء شديد جدًا؛ الكتاب كاتب فوق السهم إن الـ iron لازم يبقى أحمر من السخونية (500 °C).","feedback":"الفكرة الغلط: إن الـ iron بيدّي الـ magnetic oxide مع المية من غير تسخين."}},"explanation":"الـ iron وهو أحمر من السخونية (500 °C) بيتفاعل مع الـ water vapour: $\\ce{3Fe + 4H2O ->[500\\,^{\\circ}C] Fe3O4 + 4H2}$. وبيتكوّن الـ magnetic iron oxide والـ hydrogen gas. مع الهوا الجاف، اللي بيتكوّن هو الـ $\\ce{Fe3O4}$ لوحده. ومع الـ dilute acid، بيتكوّن iron (II) salt والـ hydrogen."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":37,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reactions-nonmetals-4","kind":"question","version":1,"ord":484,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reactions-nonmetals","concepts":[{"concept_id":"fe.reactions-nonmetals","role":"primary"},{"concept_id":"fe.occurrence","role":"secondary"}],"title":"chem-s3-en.question-fe.reactions-nonmetals-4","payload":{"stem":"Metal X is the fourth most abundant element in the earth's crust, and its ore magnetite is black and magnetic. X is heated with sulphur. What is the product, and what is the oxidation state of X in it?","tags":["exam-style","two-step"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"FeS; +2","correct":true},{"id":"b","text":"$\\ce{Fe2S3}$; +3","correct":false},{"id":"c","text":"$\\ce{FeSO4}$; +2","correct":false},{"id":"d","text":"$\\ce{Fe3S4}$; +2 and +3, like magnetic iron oxide","correct":false}],"book_ref":"Ch.1 'Chemical Properties' 3 (with non-metals), p.21; iron in the earth's crust and ores, p.16","difficulty":4,"concept_ids":["fe.reactions-nonmetals","fe.occurrence"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: X is iron (fourth most abundant in the crust, ore magnetite). Iron and sulphur give FeS, where iron is +2."},"b":{"why":"Iron reaches +3 with chlorine, but sulphur is a weaker oxidizing agent, so iron stops at +2.","feedback":"Misconception: Iron reaches +3 with any non-metal."},"c":{"why":"Only iron and sulphur react, so there is no oxygen to make a sulphate.","feedback":"Misconception: Fe + S gives $\\ce{FeSO4}$."},"d":{"why":"Heated in air, iron gives magnetic iron oxide, but with sulphur the book gives iron (II) sulphide, not a similar mixed product.","feedback":"Misconception: Iron gives a product like the magnetic oxide with every non-metal."}},"explanation":"Step 1: the fourth most abundant element in the crust, found in magnetite ($\\ce{Fe3O4}$), is iron. Step 2: iron and sulphur give iron (II) sulphide, $\\ce{Fe + S ->[\\Delta] FeS}$. Sulphur is −2, so iron is +2. Sulphur is a weaker oxidizing agent than chlorine, so iron does not reach +3."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ X هو الـ iron (الرابع في الانتشار في القشرة الأرضية، ومن الـ ores بتاعته الـ magnetite). والـ iron مع الـ sulphur بيدّي FeS، والـ iron فيه +2."},"b":{"why":"الـ iron بيوصل لـ +3 مع الـ chlorine، لكن الـ sulphur oxidizing agent أضعف، فالـ iron بيقف عند +2.","feedback":"الفكرة الغلط: إن الـ iron بيوصل لـ +3 مع أي non-metal."},"c":{"why":"مفيش oxygen يعمل sulphate: اللي بيتفاعلوا هما الـ iron والـ sulphur وبس.","feedback":"الفكرة الغلط: إن Fe + S بيدّي $\\ce{FeSO4}$."},"d":{"why":"لما الـ iron يتسخن في الهوا بيدّي magnetic iron oxide، لكن مع الـ sulphur الكتاب بيدّي iron (II) sulphide، FeS.","feedback":"الفكرة الغلط: إن الـ iron بيدّي ناتج شبه الـ magnetic oxide مع أي non-metal."}},"explanation":"الخطوة 1: العنصر الرابع في الانتشار في القشرة الأرضية، واللي بيتلاقي في الـ magnetite ($\\ce{Fe3O4}$)، هو الـ iron. الخطوة 2: الـ iron والـ sulphur بيدّوا iron (II) sulphide، $\\ce{Fe + S ->[\\Delta] FeS}$. الـ sulphur −2، فالـ iron +2. والـ sulphur oxidizing agent أضعف من الـ chlorine، فالـ iron مش بيوصل لـ +3."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":38,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reaction-dilute-acids-4","kind":"question","version":1,"ord":485,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reaction-dilute-acids","concepts":[{"concept_id":"fe.reaction-dilute-acids","role":"primary"}],"title":"chem-s3-en.question-fe.reaction-dilute-acids-4","payload":{"stem":"Consider the following statements about the hydrogen produced when iron reacts with a dilute acid: (I) It acts as a reducing agent. (II) It reduces iron (III) to iron (II). (III) It oxidizes iron to iron (III). Which statements are correct?","tags":["exam-style","correct-statements"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"(I) and (II) only","correct":true},{"id":"b","text":"(I) and (III) only","correct":false},{"id":"c","text":"(II) and (III) only","correct":false},{"id":"d","text":"(III) only","correct":false}],"book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21","difficulty":3,"concept_ids":["fe.reaction-dilute-acids"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: the produced hydrogen is a reducing agent and reduces iron (III) to iron (II); it does not oxidize iron, so (III) is false."},"b":{"why":"A reducing agent and an oxidizing agent do opposite jobs, so (I) and (III) cannot both be true.","feedback":"Misconception: Hydrogen acts as an oxidizing agent here."},"c":{"why":"(II) and (III) push iron in opposite directions; only (II) fits the iron (II) salts formed.","feedback":"Misconception: Hydrogen both reduces and oxidizes iron."},"d":{"why":"Dilute acids give iron (II) salts, which fits a reducing agent; (III) says the opposite.","feedback":"Misconception: The produced hydrogen makes iron (III) salts."}},"explanation":"Hydrogen gas forms when iron displaces it from the acid. This hydrogen is a reducing agent. It reduces iron (III) to iron (II). So the products are iron (II) salts, not iron (III) salts. Statement (III) says the opposite of what happens."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ hydrogen اللي بيطلع reducing agent وبيختزل الـ iron (III) لـ iron (II)؛ ومابيأكسدش الـ iron، فالعبارة (III) غلط."},"b":{"why":"الـ reducing agent والـ oxidizing agent شغلهم عكس بعض، فـ (I) و(III) ماينفعش يبقوا صح مع بعض.","feedback":"الفكرة الغلط: إن الـ hydrogen بيشتغل هنا كـ oxidizing agent."},"c":{"why":"(II) و(III) بيزقّوا الـ iron في اتجاهين عكس بعض، والـ iron (II) salts اللي بتتكوّن ماشية مع (II) بس.","feedback":"الفكرة الغلط: إن الـ hydrogen بيختزل الـ iron وبيأكسده في نفس الوقت."},"d":{"why":"الـ dilute acids بتدي iron (II) salts، فالعبارة (III) بتقول عكس اللي بيحصل.","feedback":"الفكرة الغلط: إن الـ hydrogen اللي بيطلع بيكوّن iron (III) salts."}},"explanation":"الـ hydrogen gas بيتكوّن لما الـ iron ياخد مكانه في الـ acid. والـ hydrogen ده reducing agent، بيختزل الـ iron (III) لـ iron (II). فالنواتج بتبقى iron (II) salts مش iron (III) salts. والعبارة (III) بتقول عكس اللي بيحصل."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":39,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reaction-conc-sulfuric-4","kind":"question","version":1,"ord":486,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reaction-conc-sulfuric","concepts":[{"concept_id":"fe.reaction-conc-sulfuric","role":"primary"}],"title":"chem-s3-en.question-fe.reaction-conc-sulfuric-4","payload":{"stem":"16.8 g of iron reacts completely with hot concentrated sulphuric acid: $\\ce{3Fe + 8H2SO4 -> FeSO4 + Fe2(SO4)3 + 4SO2 + 8H2O}$. What mass of iron (III) sulphate forms? (Fe = 56, S = 32, O = 16)","tags":["exam-style","calculation","two-step"],"type":"numeric","bloom":"apply","answer":{"unit":"g","value":40,"tolerance":0.5},"book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21","difficulty":4,"concept_ids":["fe.reaction-conc-sulfuric"],"est_seconds":150},"layer":{"explanation":"16.8 g of iron is 16.8 ÷ 56 = 0.3 mol. The equation: 3 mol Fe give 1 mol $\\ce{Fe2(SO4)3}$. So 0.1 mol forms. Molar mass of $\\ce{Fe2(SO4)3}$ = 2(56) + 3(32 + 64) = 400 g/mol. Mass = 0.1 × 400 = 40 g. Most likely wrong answer: 120 g, from taking 0.3 mol of this salt. Only 2 of every 3 Fe atoms end in it."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ 16.8 g من الـ iron = 16.8 ÷ 56 = 0.3 mol. المعادلة بتقول: 3 mol Fe بيدّوا 1 mol $\\ce{Fe2(SO4)3}$. يبقى اللي بيتكوّن 0.1 mol. الـ molar mass بتاع الـ $\\ce{Fe2(SO4)3}$ = 2(56) + 3(32 + 64) = 400 g/mol. الكتلة = 0.1 × 400 = 40 g. أشهر غلطة: 120 g، ودي بتيجي من إنك تاخد 0.3 mol من الـ salt ده. لأن من كل 3 ذرات Fe، اتنين بس هما اللي بيروحوا فيه."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":40,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.passivity-4","kind":"question","version":1,"ord":487,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.passivity","concepts":[{"concept_id":"fe.passivity","role":"primary"},{"concept_id":"te.chromium-oxide-layer","role":"secondary"}],"title":"chem-s3-en.question-fe.passivity-4","payload":{"stem":"Chromium is a highly reactive metal, yet it resists the atmosphere. Iron becomes passive in concentrated nitric acid. What do the two cases have in common?","tags":["exam-style","compare","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"A thin oxide layer on the surface protects the metal from further reaction.","correct":true},{"id":"b","text":"Both metals lose their unpaired electrons and become unreactive.","correct":false},{"id":"c","text":"Both metals are below hydrogen, so air and acids cannot attack them.","correct":false},{"id":"d","text":"In both, the protective layer is permanent and cannot be removed.","correct":false,"misconception_id":"fe.passivity.mc2"}],"book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21; chromium resists the atmosphere, p.6; exam form: compare","difficulty":2,"concept_ids":["fe.passivity","te.chromium-oxide-layer"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: chromium forms a nonporous oxide layer that stops further reaction with air, and concentrated nitric acid forms a thin oxide layer that protects iron."},"b":{"why":"Unpaired electrons explain magnetism, not this. The metal itself does not change; a thin layer forms on its surface and blocks attack.","feedback":"Misconception: Reactivity depends on unpaired electrons."},"c":{"why":"The book calls chromium highly reactive, and iron dissolves in dilute acids, so neither metal is unreactive; a layer on the surface stops them here.","feedback":"Misconception: These metals are unreactive."},"d":{"why":"The passive iron layer is not permanent: abrasion or dilute hydrochloric acid removes it.","feedback":"Misconception: Passivity is permanent."}},"explanation":"Chromium forms a nonporous oxide layer on its surface. It prevents further reaction with the oxygen of air. Concentrated nitric acid forms a thin oxide layer on iron. It protects iron from further reaction. In both, a surface oxide layer protects the metal. On iron, the layer can be removed by abrasion or dilute hydrochloric acid."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ chromium بيكوّن طبقة oxide غير مسامية بتمنعه يكمّل تفاعل مع الهوا، والـ concentrated nitric acid بيكوّن طبقة oxide رقيقة بتحمي الـ iron."},"b":{"why":"الـ unpaired electrons بتفسّر الـ magnetism، مش الحكاية دي. الـ metal نفسه مش بيتغيّر؛ فيه طبقة بتتكوّن عليه وبتمنع الهجوم.","feedback":"الفكرة الغلط: إن نشاط الـ metal بيعتمد على الـ unpaired electrons."},"c":{"why":"الكتاب بيقول إن الـ chromium highly reactive، والـ iron بيدوب في الـ dilute acids؛ اللي موقّفهم هنا طبقة oxide على السطح.","feedback":"الفكرة الغلط: إن الـ metals دي مش نشطة."},"d":{"why":"طبقة الـ passivity اللي على الـ iron مش دايمة: الكتاب بيقول إنها بتتشال بالـ abrasion أو بالـ dilute hydrochloric acid.","feedback":"الفكرة الغلط: إن الـ passivity دايمة."}},"explanation":"الـ chromium بيكوّن طبقة oxide غير مسامية (nonporous) على سطحه، بتمنعه من إنه يكمّل تفاعل مع الـ oxygen اللي في الهوا. والـ concentrated nitric acid بيكوّن طبقة رقيقة من الـ oxide على الـ iron، بتحميه من إنه يكمّل تفاعل. يعني في الحالتين، طبقة oxide على السطح هي اللي بتحمي الـ metal. وفي حالة الـ iron، الطبقة دي ممكن تتشال بالـ abrasion أو بالـ dilute hydrochloric acid."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":41,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":6,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reaction-dilute-acids-5","kind":"question","version":1,"ord":488,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.reaction-dilute-acids","concepts":[{"concept_id":"fe.reaction-dilute-acids","role":"primary"}],"title":"chem-s3-en.question-fe.reaction-dilute-acids-5","payload":{"stem":"What happens when 5.6 g of iron reacts completely with dilute hydrochloric acid? Write the balanced equation and calculate the mass of the salt formed. (Fe = 56, Cl = 35.5)","tags":["exam-style","what-happens","calculation"],"type":"short","bloom":"apply","answer":"Key points: (1) $\\ce{Fe(s) + 2HCl(aq) ->[(dil)] FeCl2(aq) + H2(g)}$: iron (II) chloride and hydrogen gas form. (2) Moles of Fe = 5.6 ÷ 56 = 0.1 mol. (3) 1 mol Fe gives 1 mol $\\ce{FeCl2}$, so 0.1 mol forms. (4) Molar mass of $\\ce{FeCl2}$ = 56 + 2(35.5) = 127 g/mol, so the mass = 12.7 g.","book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21; exam form: what happens when","difficulty":4,"concept_ids":["fe.reaction-dilute-acids"],"est_seconds":150},"layer":{"explanation":"Iron dissolves in dilute HCl. Hydrogen gas is given off, and iron (II) chloride forms. 5.6 g of iron is 0.1 mol, which gives 0.1 mol of $\\ce{FeCl2}$. 0.1 × 127 = 12.7 g. Most likely wrong answer: 16.25 g, from writing $\\ce{FeCl3}$ (molar mass 162.5 g/mol)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ iron بيدوب في الـ dilute HCl، وبيطلع hydrogen gas، ويتكوّن iron (II) chloride. الـ 5.6 g من الـ iron دول 0.1 mol، وبيدوا 0.1 mol من الـ $\\ce{FeCl2}$. و0.1 × 127 = 12.7 g. أشهر إجابة غلط: 16.25 g، ودي بتيجي من إنك تكتب $\\ce{FeCl3}$ (الـ molar mass بتاعه 162.5 g/mol)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":42,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":30,"page_to":30,"section_key":"ch2","section_title":"Chemical analysis","section_path":["Chemical analysis"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.ores-5","kind":"question","version":1,"ord":489,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"fe.ores","concepts":[{"concept_id":"fe.ores","role":"primary"},{"concept_id":"pt.oxidation-number","role":"secondary"}],"title":"chem-s3-en.question-fe.ores-5","payload":{"stem":"Match each ore in column (A) with the oxidation state of iron in it and its colour in column (B).","tags":["mixed","retrieval","match"],"type":"match","bloom":"apply","answer":[["l1","r2"],["l2","r3"],["l3","r1"]],"choices":[{"id":"l1","text":"Hematite ($\\ce{Fe2O3}$)"},{"id":"l2","text":"Limonite ($\\ce{2Fe2O3.3H2O}$)"},{"id":"l3","text":"Siderite ($\\ce{FeCO3}$)"},{"id":"r1","text":"+2; yellowish grey"},{"id":"r2","text":"+3; blood red"},{"id":"r3","text":"+3; yellow"}],"book_ref":"Ch.1 'IRON', table of the most important iron ores, p.16; exam form: match columns","difficulty":3,"concept_ids":["fe.ores","pt.oxidation-number"],"est_seconds":75},"layer":{"choices":{"l1":{"why":"In $\\ce{Fe2O3}$ three O give −6, shared by two Fe, so iron is +3; hematite is blood red."},"l2":{"why":"In $\\ce{2Fe2O3.3H2O}$ the water adds no charge, so iron is +3 as in $\\ce{Fe2O3}$; limonite is yellow."},"l3":{"why":"In $\\ce{FeCO3}$ carbonate is −2, so iron is +2; siderite is yellowish grey."},"r1":{"why":"+2 fits siderite: carbonate is −2 in $\\ce{FeCO3}$, and siderite is the yellowish grey ore."},"r2":{"why":"+3 and blood red fit hematite, $\\ce{Fe2O3}$: three O give −6 over two Fe."},"r3":{"why":"+3 and yellow fit limonite, $\\ce{2Fe2O3.3H2O}$: the water does not change iron's oxidation state."}},"explanation":"Hematite, $\\ce{Fe2O3}$: three O give −6, shared by two Fe, so iron is +3; blood red. Limonite, $\\ce{2Fe2O3.3H2O}$: the water adds no charge, so iron is again +3; yellow. Siderite, $\\ce{FeCO3}$: carbonate is −2, so iron is +2; yellowish grey. Common slip: thinking the water in limonite changes iron's oxidation state."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"l1":{"why":"في الـ $\\ce{Fe2O3}$ تلات O بيدّوا −6، متقسمين على اتنين Fe، يبقى الـ iron عنده +3؛ والـ hematite لونه أحمر دموي."},"l2":{"why":"في الـ $\\ce{2Fe2O3.3H2O}$ المية مش بتضيف أي charge، يبقى الـ iron عنده +3 زي الـ $\\ce{Fe2O3}$؛ والـ limonite لونه أصفر."},"l3":{"why":"في الـ $\\ce{FeCO3}$ الـ carbonate عليه −2، يبقى الـ iron عنده +2؛ والـ siderite لونه رمادي مصفرّ."},"r1":{"why":"الـ +2 بتاعة الـ siderite: الـ carbonate عليه −2 في الـ $\\ce{FeCO3}$، والـ siderite هو الـ ore الرمادي المصفرّ."},"r2":{"why":"الـ +3 مع الأحمر الدموي بتوع الـ hematite، $\\ce{Fe2O3}$: تلات O بيدّوا −6 على اتنين Fe."},"r3":{"why":"الـ +3 مع الأصفر بتوع الـ limonite، $\\ce{2Fe2O3.3H2O}$: المية مش بتغيّر الـ oxidation state بتاع الـ iron."}},"explanation":"الـ Hematite، $\\ce{Fe2O3}$: تلات O بيدّوا −6، متقسمين على اتنين Fe، يبقى الـ iron عنده +3؛ ولونه أحمر دموي. الـ Limonite، $\\ce{2Fe2O3.3H2O}$: المية مش بتضيف أي charge، يبقى الـ iron برضه +3؛ ولونه أصفر. الـ Siderite، $\\ce{FeCO3}$: الـ carbonate عليه −2، يبقى الـ iron عنده +2؛ ولونه رمادي مصفرّ. غلطة بتتكرر: إنك تفتكر إن المية اللي في الـ limonite بتغيّر الـ oxidation state بتاع الـ iron."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":63,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":16,"page_to":16,"section_key":"ch1.iron.ores","section_title":"Iron ores","section_path":["Transition Elements","Iron","Iron ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.interstitial-5","kind":"question","version":1,"ord":490,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"alloy.interstitial","concepts":[{"concept_id":"alloy.interstitial","role":"primary"},{"concept_id":"fe.physical-properties","role":"secondary"}],"title":"chem-s3-en.question-alloy.interstitial-5","payload":{"stem":"Give reasons: A bar of pure iron bends more easily than a bar of steel of the same size.","tags":["mixed","retrieval","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) In pure iron, atoms are arranged in compact closed rows, and a layer can slip over the other layers, so it is relatively soft. (2) Steel is an interstitial alloy: small carbon atoms enter the spaces of the iron lattice. (3) They prevent the movement of the layers, so steel is harder. Not accepted: \"carbon replaces iron atoms\" (that is a substitutional alloy).","book_ref":"Ch.1 'Types of alloys', 1-Interstitial alloys, p.19; 'Properties of Iron', p.20; exam form: give reasons","difficulty":2,"concept_ids":["alloy.interstitial","fe.physical-properties"],"est_seconds":75},"layer":{"explanation":"Pure iron is relatively soft. Its layers of atoms slip over each other when a force acts. In steel, carbon atoms with a small atomic size sit in the spaces of the iron lattice. They block the layers from slipping. So steel is harder and bends less. Key words: spaces of the crystal lattice, prevent the movement of the layers. Most likely wrong answer: \"carbon atoms replace iron atoms in the lattice.\" That describes a substitutional alloy, where atoms of similar diameter take the places of the main metal's atoms. Carbon atoms are much smaller than iron atoms, so they do not take iron's places; they sit in the spaces between iron atoms, and every iron atom stays in place."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ iron النقي طري نسبيًا: طبقات الذرات بتاعته بتنزلق فوق بعض لما قوة تأثر عليه. في الـ steel، ذرات الـ carbon اللي الـ atomic size بتاعها صغير بتقعد في فراغات الـ lattice بتاع الـ iron وبتمنع الطبقات إنها تنزلق. عشان كده الـ steel أصلب وبيتني أقل. الكلمات المفتاحية: spaces of the crystal lattice، prevent the movement of the layers. أكتر إجابة غلط بتتكتب: \"carbon atoms replace iron atoms in the lattice.\" ده وصف الـ substitutional alloy، اللي فيه ذرات قطرها قريب من بعض بتاخد أماكن ذرات الـ metal الأساسي. وذرات الـ carbon أصغر بكتير من ذرات الـ iron، فمش بتاخد أماكنها؛ هي بتقعد في الفراغات اللي بين ذرات الـ iron، وكل ذرة iron بتفضل في مكانها."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":31,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.properties","section_title":"Properties of Iron","section_path":["Transition Elements","Iron","Properties of Iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.fe2-fe3-mn2-stability-6","kind":"question","version":1,"ord":491,"group_id":"chem-s3-en.ch1.practice.fe-reactions","primary_concept_id":"te.fe2-fe3-mn2-stability","concepts":[{"concept_id":"te.fe2-fe3-mn2-stability","role":"primary"},{"concept_id":"fe.reaction-dilute-acids","role":"secondary"}],"title":"chem-s3-en.question-te.fe2-fe3-mn2-stability-6","payload":{"stem":"Consider the following statements ($_{26}$Fe): (I) In $\\ce{FeCl3}$, formed from iron and chlorine, iron has a half-filled $3d^5$ sublevel. (II) Iron gives iron (II) salts with dilute acids because $\\ce{Fe^{2+}}$ is more stable than $\\ce{Fe^{3+}}$. (III) The $\\ce{Fe^{2+}}$ ion has the configuration [Ar] $3d^6$. Which statements are correct?","tags":["mixed","retrieval","correct-statements"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"(I) and (III) only","correct":true},{"id":"b","text":"(I) and (II) only","correct":false},{"id":"c","text":"(II) and (III) only","correct":false},{"id":"d","text":"(I), (II) and (III)","correct":false}],"book_ref":"Ch.1 oxidation states, p.9; chemical properties of iron, pp.20-21","difficulty":3,"concept_ids":["te.fe2-fe3-mn2-stability","fe.reaction-dilute-acids"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Correct! (I): iron in $\\ce{FeCl3}$ is $\\ce{Fe^{3+}}$, [Ar] $3d^5$, half-filled. (III): $\\ce{Fe^{2+}}$ is [Ar] $3d^6$. (II) is wrong: $\\ce{Fe^{3+}}$ is the more stable ion, and iron (II) salts form because the produced hydrogen reduces iron (III)."},"b":{"why":"(II) is wrong: $3d^5$, not $3d^6$, is half-filled, so $\\ce{Fe^{3+}}$ is the more stable ion. And (III) is correct: Fe becomes [Ar] $3d^6$ after losing its two 4s electrons.","feedback":"Misconception: $\\ce{Fe^{2+}}$ is more stable than $\\ce{Fe^{3+}}$."},"c":{"why":"(II) is false: $\\ce{Fe^{3+}}$ ($3d^5$, half-filled) is the more stable ion; iron (II) salts form because the produced hydrogen reduces iron (III) to iron (II).","feedback":"Misconception: $\\ce{Fe^{2+}}$ is more stable than $\\ce{Fe^{3+}}$."},"d":{"why":"(II) gives the wrong reason: in the dilute-acid reaction the produced hydrogen reduces iron (III) to iron (II); the iron (II) salt does not form because Fe²⁺ is more stable.","feedback":"Misconception: Stability explains the iron (II) salts from dilute acids."}},"explanation":"(I) is correct: in $\\ce{FeCl3}$ iron is +3, and $\\ce{Fe^{3+}}$ is [Ar] $3d^5$, half-filled. (III) is correct: Fe loses its two 4s electrons to give [Ar] $3d^6$. (II) is wrong. $\\ce{Fe^{3+}}$ ($3d^5$) is the more stable ion. Iron (II) salts form because the produced hydrogen reduces iron (III) to iron (II)."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! (I): الـ iron في الـ $\\ce{FeCl3}$ بيبقى $\\ce{Fe^{3+}}$، يعني [Ar] $3d^5$، نصه مليان. (III): الـ $\\ce{Fe^{2+}}$ هو [Ar] $3d^6$. أما (II) فغلط: الـ $\\ce{Fe^{3+}}$ هو الـ ion الأكتر استقرارًا، وأملاح الـ iron (II) بتتكوّن عشان الـ hydrogen اللي بيطلع بيختزل الـ iron (III)."},"b":{"why":"(II) غلط: الـ $3d^5$، مش الـ $3d^6$، هو اللي half-filled، فالـ $\\ce{Fe^{3+}}$ هو الـ ion الأكتر استقرارًا. وكمان (III) صح: الـ Fe بيبقى [Ar] $3d^6$ بعد ما يخسر الاتنين 4s electrons بتوعه.","feedback":"الفكرة الغلط: إن الـ $\\ce{Fe^{2+}}$ أكتر استقرارًا من الـ $\\ce{Fe^{3+}}$."},"c":{"why":"(II) غلط: الـ $\\ce{Fe^{3+}}$ ($3d^5$، نصه مليان) هو الـ ion الأكتر استقرارًا، وأملاح الـ iron (II) بتتكوّن عشان الـ hydrogen اللي بيطلع بيختزل الـ iron (III) لـ iron (II).","feedback":"الفكرة الغلط: إن الـ $\\ce{Fe^{2+}}$ أكتر استقرارًا من الـ $\\ce{Fe^{3+}}$."},"d":{"why":"(II) بتدّي سبب غلط: في التفاعل مع الـ dilute acids الـ hydrogen اللي بيطلع بيختزل الـ iron (III) لـ iron (II)؛ ملح الـ iron (II) مش بيتكوّن عشان الـ Fe²⁺ أكتر استقرارًا.","feedback":"الفكرة الغلط: إن الاستقرار هو اللي بيفسّر تكوين أملاح الـ iron (II) مع الـ dilute acids."}},"explanation":"(I) صح: في الـ $\\ce{FeCl3}$ الـ iron بيبقى +3، والـ $\\ce{Fe^{3+}}$ تركيبه [Ar] $3d^5$، نصه مليان. (III) صح: الـ Fe بيخسر الاتنين 4s electrons بتوعه فيبقى [Ar] $3d^6$. (II) غلط: الـ $\\ce{Fe^{3+}}$ ($3d^5$) هو الـ ion الأكتر استقرارًا. أملاح الـ iron (II) بتتكوّن عشان الـ hydrogen اللي بيطلع بيختزل الـ iron (III) لـ iron (II)."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":74,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-feo-1","kind":"question","version":1,"ord":502,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-feo","concepts":[{"concept_id":"fe.oxide-feo","role":"primary"}],"title":"chem-s3-en.question-fe.oxide-feo-1","payload":{"stem":"Write the balanced equation for the preparation of iron (II) oxide from iron (II) oxalate, with the condition over the arrow.","tags":["exam-style","equation"],"type":"short","bloom":"remember","answer":"\\ce{FeC2O4(s) ->[\\Delta][\\text{in absence of air}] FeO(s) + CO(g) + CO2(g)}","book_ref":"Ch.1 'IRON Oxides' 1-Iron (II) oxide, p.22; exam form: write the equation","difficulty":3,"concept_ids":["fe.oxide-feo"],"est_seconds":75},"layer":{"explanation":"Heating iron (II) oxalate breaks it down into FeO, carbon monoxide and carbon dioxide. The book draws the oxalate as two COO groups joined to Fe. Air must be absent. Otherwise hot air oxidizes the FeO to $\\ce{Fe2O3}$. Most likely slip: leaving out CO, or the condition 'in absence of air'."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"لما تسخّن الـ iron (II) oxalate بيتكسّر ويدّي FeO و carbon monoxide و carbon dioxide. الكتاب بيرسم الـ oxalate على إنه اتنين COO groups مربوطين بالـ Fe. ولازم الهوا يبقى مش موجود، وإلا الهوا السخن هيأكسد الـ FeO ويحوّله لـ $\\ce{Fe2O3}$. أشهر غلطة: إنك تنسى الـ CO، أو تنسى الشرط 'in absence of air'."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":9,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-fe2o3-1","kind":"question","version":1,"ord":503,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-fe2o3","concepts":[{"concept_id":"fe.oxide-fe2o3","role":"primary"}],"title":"chem-s3-en.question-fe.oxide-fe2o3-1","payload":{"stem":"Write the balanced equation for heating iron (II) sulphate strongly.","tags":["exam-style","equation"],"type":"short","bloom":"remember","answer":"\\ce{2FeSO4(s) ->[\\Delta] Fe2O3(s) + SO2(g) + SO3(g)}","book_ref":"Ch.1 'IRON Oxides' 2-Iron (III) oxide, pp.22-23; Evaluation Q1.6, p.25; exam form: write the equation","difficulty":3,"concept_ids":["fe.oxide-fe2o3"],"est_seconds":60},"layer":{"explanation":"Heating iron (II) sulphate gives iron (III) oxide, sulphur dioxide and sulphur trioxide. Iron is oxidized from +2 to +3. One S is reduced from +6 to +4 in $\\ce{SO2}$; the other stays +6 in $\\ce{SO3}$. Most likely wrong answer: FeO and $\\ce{SO3}$ only."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"لما تسخّن الـ iron (II) sulphate بيدّي iron (III) oxide و sulphur dioxide و sulphur trioxide. الـ iron بيتأكسد (oxidized) من +2 لـ +3. وذرة S واحدة بتتختزل (reduced) من +6 لـ +4 في الـ $\\ce{SO2}$، والتانية بتفضل +6 في الـ $\\ce{SO3}$. أشهر غلطة: إنك تكتب FeO و $\\ce{SO3}$ لوحدهم."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":10,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-fe3o4-1","kind":"question","version":2,"ord":504,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-fe3o4","concepts":[{"concept_id":"fe.oxide-fe3o4","role":"primary"}],"title":"chem-s3-en.question-fe.oxide-fe3o4-1","payload":{"stem":"Magnetic iron oxide is heated with concentrated sulphuric acid. The products are ...","tags":["exam-style","choose"],"type":"mcq","bloom":"remember","choices":[{"id":"a","text":"$\\ce{FeSO4}$, $\\ce{Fe2(SO4)3}$ and water","correct":true},{"id":"b","text":"$\\ce{Fe2(SO4)3}$ and water only","correct":false,"misconception_id":"fe.oxide-fe3o4.mc1"},{"id":"c","text":"$\\ce{FeSO4}$ and water only","correct":false,"misconception_id":"fe.oxide-fe3o4.mc1"},{"id":"d","text":"$\\ce{FeSO4}$, $\\ce{Fe2(SO4)3}$, $\\ce{SO2}$ and water","correct":false}],"book_ref":"Ch.1 'IRON Oxides' 3-The black oxide (magnetic iron oxide), pp.23-24; Evaluation Q1.3, p.25","difficulty":2,"concept_ids":["fe.oxide-fe3o4"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: $\\ce{Fe3O4}$ is a mixed iron (II) and iron (III) oxide, so with the hot concentrated acid it gives both salts and water, and no gas."},"b":{"why":"$\\ce{Fe3O4}$ holds iron in two oxidation states, +2 and +3, so it gives two salts.","feedback":"Misconception: $\\ce{Fe3O4}$ is a single iron (III) oxide."},"c":{"why":"$\\ce{Fe3O4}$ acts like FeO + $\\ce{Fe2O3}$: the FeO part gives an iron (II) salt and the $\\ce{Fe2O3}$ part gives an iron (III) salt.","feedback":"Misconception: $\\ce{Fe3O4}$ gives only an iron (II) salt."},"d":{"why":"Sulphur dioxide forms when iron metal reacts with the hot acid. An oxide gives only salts and water; the acid is not reduced.","feedback":"Misconception: The oxide reacts like iron metal with the hot concentrated acid."}},"explanation":"$\\ce{Fe3O4}$ is a mixed iron (II) and iron (III) oxide. With hot concentrated acids, it gives iron (II) and iron (III) salts and water: $\\ce{Fe3O4 + 4H2SO4 -> FeSO4 + Fe2(SO4)3 + 4H2O}$. No gas forms. Iron metal, not its oxide, gives $\\ce{SO2}$ with the hot concentrated acid."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ $\\ce{Fe3O4}$ هو mixed oxide فيه iron (II) و iron (III)، فمع الـ hot concentrated acid بيدّي الـ salts الاتنين ومية، ومن غير أي gas."},"b":{"why":"الـ $\\ce{Fe3O4}$ فيه iron بـ 2 oxidation states (+2 و +3)، فبيدّي ملحين، مش iron (III) salt واحد.","feedback":"الفكرة الغلط: إن الـ $\\ce{Fe3O4}$ مجرد iron (III) oxide واحد."},"c":{"why":"الـ $\\ce{Fe3O4}$ ينفع يتعامل على إنه FeO + $\\ce{Fe2O3}$: الـ FeO بيدّي iron (II) salt والـ $\\ce{Fe2O3}$ بيدّي iron (III) salt.","feedback":"الفكرة الغلط: إن الـ $\\ce{Fe3O4}$ بيدّي iron (II) salt لوحده."},"d":{"why":"الـ sulphur dioxide بيطلع لما الـ iron metal يتفاعل مع الـ acid السخن. لما الـ oxide هو اللي بيتفاعل، الـ acid مابيتختزلش، فبيطلع salts ومية بس.","feedback":"الفكرة الغلط: إن الـ oxide بيتفاعل مع الـ hot concentrated acid زي الـ iron metal."}},"explanation":"الـ $\\ce{Fe3O4}$ هو mixed oxide فيه iron (II) و iron (III). مع الـ hot concentrated acids بيدّي iron (II) salt و iron (III) salt ومية: $\\ce{Fe3O4 + 4H2SO4 -> FeSO4 + Fe2(SO4)3 + 4H2O}$. ومفيش أي gas بيطلع. الـ iron metal، مش الـ oxide بتاعه، هو اللي بيدّي $\\ce{SO2}$ مع الـ hot concentrated acid."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":11,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":25,"page_to":25,"section_key":"ch1.eval.q1","section_title":"Choose the correct answer","section_path":["Transition Elements","Evaluation","Choose the correct answer"],"exercise":"Question 1","question":"3","relation":"from_book"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":24,"page_to":24,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.conversions-1","kind":"question","version":1,"ord":505,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.conversions","concepts":[{"concept_id":"fe.conversions","role":"primary"},{"concept_id":"fe.oxide-feo","role":"secondary"},{"concept_id":"fe.reactions-air-steam","role":"secondary"}],"title":"chem-s3-en.question-fe.conversions-1","payload":{"stem":"Write the balanced equations for the conversions Fe → $\\ce{Fe3O4}$ → FeO. Use water vapour in the first step and carbon monoxide in the second. Write the condition over each arrow.","tags":["exam-style","conversion","equation"],"type":"short","bloom":"apply","answer":"(1) $\\ce{3Fe + 4H2O(v) ->[500\\,^{\\circ}C] Fe3O4 + 4H2}$. (2) $\\ce{Fe3O4 + CO ->[400-700\\,^{\\circ}C] 3FeO + CO2}$.","book_ref":"Ch.1 Evaluation Q6 (conversion diagrams), p.26; reactions pp.18, 21-24","difficulty":3,"concept_ids":["fe.conversions","fe.reactions-air-steam","fe.oxide-feo"],"est_seconds":120},"layer":{"explanation":"Step 1: red hot iron (500 °C) reacts with water vapour to give magnetic iron oxide and hydrogen. Step 2: higher oxides are reduced by CO (or $\\ce{H2}$) at 400–700 °C to FeO. The 3 Fe in $\\ce{Fe3O4}$ give 3 FeO; the fourth O joins CO as $\\ce{CO2}$. Most likely slip: iron as the step 2 product. That needs higher than 700 °C."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الخطوة 1: الـ iron المسخّن لدرجة الاحمرار (500 °C) بيتفاعل مع بخار المية ويدي magnetic iron oxide والـ hydrogen. الخطوة 2: الـ oxides الأعلى بيحصلها reduction بالـ CO (أو $\\ce{H2}$) عند 400–700 °C لحد FeO. الـ 3 Fe اللي في الـ $\\ce{Fe3O4}$ بيدوا 3 FeO؛ والـ O الرابع بيروح للـ CO ويبقى $\\ce{CO2}$. أشهر غلطة: إنك تكتب iron ناتج للخطوة 2. ده محتاج حرارة أعلى من 700 °C."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":12,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q6","section_title":"Write complete equations for the diagrams","section_path":["Transition Elements","Evaluation","Write complete equations for the diagrams"],"exercise":"Question 6","question":"a","relation":"from_book"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-feo-2","kind":"question","version":1,"ord":506,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-feo","concepts":[{"concept_id":"fe.oxide-feo","role":"primary"}],"title":"chem-s3-en.question-fe.oxide-feo-2","payload":{"stem":"Give reasons: Iron (II) oxalate is heated in the absence of air to prepare iron (II) oxide.","tags":["exam-style","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) FeO is easily oxidized in hot air. (2) In air it would change to iron (III) oxide: $\\ce{4FeO + O2 ->[\\Delta] 2Fe2O3}$. (3) So air is kept out to obtain FeO.","book_ref":"Ch.1 'IRON Oxides' 1-Iron (II) oxide, p.22; exam form: give reasons","difficulty":2,"concept_ids":["fe.oxide-feo"],"est_seconds":60},"layer":{"explanation":"Heating iron (II) oxalate gives FeO, CO and $\\ce{CO2}$. FeO is easily oxidized in hot air to $\\ce{Fe2O3}$. Heating in absence of air keeps the product as FeO. Key words: easily oxidized in hot air. Most likely wrong answer: 'the oxalate does not decompose in air'. It does; the product is the problem."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"تسخين الـ iron (II) oxalate بيدّي FeO و CO و $\\ce{CO2}$. والـ FeO بيتأكسد بسهولة في الهوا السخن ويتحوّل لـ $\\ce{Fe2O3}$. عشان كده التسخين in absence of air بيخلّي الناتج يفضل FeO. الكلمات المهمة: easily oxidized in hot air. أشهر إجابة غلط: 'the oxalate does not decompose in air'. لأ، هو بيتكسّر عادي؛ المشكلة في الناتج."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":13,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-fe2o3-2","kind":"question","version":1,"ord":507,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-fe2o3","concepts":[{"concept_id":"fe.oxide-fe2o3","role":"primary"}],"title":"chem-s3-en.question-fe.oxide-fe2o3-2","payload":{"stem":"An iron oxide is found in nature as hematite and is used in red pigments in paints. Which statement about this oxide is correct?","tags":["exam-style","two-step"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"It is $\\ce{Fe2O3}$; it is insoluble in water and gives an iron (III) salt and water with hot concentrated acids.","correct":true},{"id":"b","text":"It is $\\ce{Fe3O4}$; it is a strong magnet and gives two salts with hot concentrated acids.","correct":false},{"id":"c","text":"It is $\\ce{Fe2O3}$; it gives an iron (II) salt and water with hot concentrated acids.","correct":false},{"id":"d","text":"It is FeO; it is easily oxidized in hot air.","correct":false}],"book_ref":"Ch.1 'IRON Oxides' 2-Iron (III) oxide, pp.22-23","difficulty":2,"concept_ids":["fe.oxide-fe2o3"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: hematite is iron (III) oxide, $\\ce{Fe2O3}$; it is insoluble in water, and with hot concentrated acids it gives iron (III) salts and water."},"b":{"why":"The black magnetic ore is magnetite, not the red ore hematite.","feedback":"Misconception: Hematite is the magnetic oxide."},"c":{"why":"Iron is +3 in $\\ce{Fe2O3}$, and its reaction with an acid does not change that, so it gives an iron (III) salt.","feedback":"Misconception: $\\ce{Fe2O3}$ gives iron (II) salts."},"d":{"why":"FeO is black; the red oxide used in paints is iron (III) oxide ($\\ce{Fe2O3}$).","feedback":"Misconception: The red oxide is FeO."}},"explanation":"Hematite is iron (III) oxide, $\\ce{Fe2O3}$. It is used in red pigments in paints. It is insoluble in water. With hot concentrated acids it gives iron (III) salts and water: $\\ce{Fe2O3 + 3H2SO4 -> Fe2(SO4)3 + 3H2O}$. Iron stays +3."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ hematite هو iron (III) oxide، $\\ce{Fe2O3}$؛ مابيدوبش في المية، ومع الـ hot concentrated acids بيدّي iron (III) salts ومية."},"b":{"why":"الـ ore الأسود المغناطيسي هو الـ magnetite، مش الـ hematite الأحمر.","feedback":"الفكرة الغلط: إن الـ hematite هو الـ oxide المغناطيسي."},"c":{"why":"الـ iron في الـ $\\ce{Fe2O3}$ عنده +3، والتفاعل مع الـ acid مش بيغيّرها، فبيدّي iron (III) salts.","feedback":"الفكرة الغلط: إن الـ $\\ce{Fe2O3}$ بيدّي iron (II) salts."},"d":{"why":"الـ FeO مش هو الـ oxide الأحمر؛ الـ oxide الأحمر اللي في البويات هو الـ $\\ce{Fe2O3}$.","feedback":"الفكرة الغلط: إن الـ oxide الأحمر هو الـ FeO."}},"explanation":"الـ hematite هو الـ iron (III) oxide، يعني $\\ce{Fe2O3}$. بيستخدم في الـ red pigments في البويات، ومابيدوبش في المية. ومع الـ hot concentrated acids بيدّي iron (III) salts ومية: $\\ce{Fe2O3 + 3H2SO4 -> Fe2(SO4)3 + 3H2O}$. والـ iron بيفضل +3."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":14,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-fe3o4-2","kind":"question","version":1,"ord":508,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-fe3o4","concepts":[{"concept_id":"fe.oxide-fe3o4","role":"primary"}],"title":"chem-s3-en.question-fe.oxide-fe3o4-2","payload":{"stem":"Give reasons: Magnetic iron oxide, $\\ce{Fe3O4}$, is considered a mixed oxide.","tags":["exam-style","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) It can be considered as mixed iron (II) and iron (III) oxides (FeO + $\\ce{Fe2O3}$). (2) It reacts with hot concentrated acids to give iron (II) and iron (III) salts: $\\ce{Fe3O4 + 4H2SO4 -> FeSO4 + Fe2(SO4)3 + 4H2O}$. (3) Two salts prove two oxidation states of iron.","book_ref":"Ch.1 'IRON Oxides' 3-The black oxide (magnetic iron oxide), pp.23-24; exam form: give reasons","difficulty":2,"concept_ids":["fe.oxide-fe3o4"],"est_seconds":75},"layer":{"explanation":"An oxide with one oxidation state gives one kind of salt. $\\ce{Fe3O4}$ gives two: an iron (II) salt and an iron (III) salt. So it contains iron (II) and iron (III) together. Key words: gives iron (II) and iron (III) salts, proving it is a mixed oxide. Most likely wrong answer: 'because it is magnetic'. Magnetism does not show two oxidation states."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ oxide اللي فيه oxidation state واحدة بيدّي نوع واحد من الأملاح. لكن الـ $\\ce{Fe3O4}$ بيدّي نوعين: iron (II) salt و iron (III) salt. يعني فيه iron (II) و iron (III) مع بعض. الكلمات المفتاحية: gives iron (II) and iron (III) salts, proving it is a mixed oxide. أشهر غلطة: إنك تكتب 'because it is magnetic'. إنه magnetic ده مش بيبيّن 2 oxidation states."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":15,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":24,"page_to":24,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.conversions-2","kind":"question","version":1,"ord":509,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.conversions","concepts":[{"concept_id":"fe.conversions","role":"primary"},{"concept_id":"fe.midrex-reduction","role":"secondary"}],"title":"chem-s3-en.question-fe.conversions-2","payload":{"stem":"Write the balanced equations for the conversions FeO → $\\ce{Fe2O3}$ → Fe, where the second step takes place in the Midrex furnace. Write the condition over each arrow.","tags":["exam-style","conversion","equation"],"type":"short","bloom":"apply","answer":"(1) $\\ce{4FeO + O2 ->[\\Delta] 2Fe2O3}$ (heating in hot air). (2) $\\ce{2Fe2O3 + 3CO + 3H2 ->[\\Delta] 4Fe + 3CO2 + 3H2O}$ (water gas from natural gas).","book_ref":"Ch.1 Evaluation Q6 (conversion diagrams), p.26; reactions pp.18, 21-24; Midrex furnace, p.18","difficulty":4,"concept_ids":["fe.conversions","fe.midrex-reduction"],"est_seconds":120},"layer":{"explanation":"Step 1: FeO is easily oxidized in hot air to $\\ce{Fe2O3}$. Step 2: in the Midrex furnace, water gas (CO + $\\ce{H2}$) from natural gas reduces $\\ce{Fe2O3}$ to iron. CO becomes $\\ce{CO2}$, and $\\ce{H2}$ becomes $\\ce{H2O}$. Most likely slip: using CO alone, as in the blast furnace. The Midrex reducing agent is a mixture of CO and $\\ce{H2}$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الخطوة 1: الـ FeO بيحصله oxidation بسهولة في الهوا السخن ويبقى $\\ce{Fe2O3}$. الخطوة 2: في الـ Midrex furnace، الـ water gas (CO + $\\ce{H2}$) اللي جاي من الـ natural gas بيعمل reduction للـ $\\ce{Fe2O3}$ لحد الـ iron. الـ CO بيبقى $\\ce{CO2}$، والـ $\\ce{H2}$ بيبقى $\\ce{H2O}$. أشهر غلطة: إنك تستخدم الـ CO لوحده، زي الـ blast furnace. الـ reducing agent في الـ Midrex خليط من الـ CO والـ $\\ce{H2}$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":16,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":26,"page_to":26,"section_key":"ch1.eval.q6","section_title":"Write complete equations for the diagrams","section_path":["Transition Elements","Evaluation","Write complete equations for the diagrams"],"exercise":"Question 6","question":"a","relation":"from_book"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-feo-3","kind":"question","version":2,"ord":510,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-feo","concepts":[{"concept_id":"fe.oxide-feo","role":"primary"}],"title":"chem-s3-en.question-fe.oxide-feo-3","payload":{"stem":"Which statement about iron (II) oxide, FeO, is correct?","tags":["exam-style","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"It is a black powder, insoluble in water, and gives an iron (II) salt and water with dilute acids.","correct":true},{"id":"b","text":"It is a red powder used in red pigments in paints.","correct":false,"misconception_id":"fe.oxide-feo.mc3"},{"id":"c","text":"It is a black powder that gives an iron (III) salt and water with dilute acids.","correct":false,"misconception_id":"fe.oxide-feo.mc2"},{"id":"d","text":"It is a black powder that gives an iron (II) salt and hydrogen gas with dilute acids.","correct":false}],"book_ref":"Ch.1 'IRON Oxides' 1-Iron (II) oxide, p.22; Evaluation Q1.5, p.25","difficulty":2,"concept_ids":["fe.oxide-feo"],"est_seconds":45},"layer":{"choices":{"a":{"why":"Right: FeO is a black powder, insoluble in water, and with dilute acids it gives an iron (II) salt and water; iron stays +2."},"b":{"why":"The iron oxide in red paints and in hematite is iron (III) oxide ($\\ce{Fe2O3}$), not the oxide of iron (II).","feedback":"Misconception: FeO is red."},"c":{"why":"Iron is +2 in FeO, and a dilute acid does not oxidize it here, so the salt stays iron (II).","feedback":"Misconception: FeO + dilute acid gives an iron (III) salt."},"d":{"why":"Hydrogen forms when a metal such as iron reacts with a dilute acid. A metal oxide gives a salt and water, with no gas.","feedback":"Misconception: A metal oxide gives hydrogen with an acid."}},"explanation":"FeO is a black powder, insoluble in water. It is easily oxidized in hot air. With dilute acids it gives an iron (II) salt and water: $\\ce{FeO + H2SO4 -> FeSO4 + H2O}$. Iron stays +2, and no gas forms."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ FeO هو black powder، و insoluble in water، ومع الـ dilute acids بيدّي iron (II) salt و water؛ والـ iron بيفضل +2."},"b":{"why":"الـ iron oxide اللي في الـ red paints وفي الـ hematite هو الـ $\\ce{Fe2O3}$، مش oxide الـ iron (II). الـ FeO لونه أسود.","feedback":"الفكرة الغلط: إن الـ FeO لونه أحمر."},"c":{"why":"الـ iron في الـ FeO عنده +2، والـ dilute acid مابيعملوش oxidize هنا، فبيدّي iron (II) salt.","feedback":"الفكرة الغلط: إن الـ FeO مع الـ dilute acid بيدّي iron (III) salt."},"d":{"why":"الـ Hydrogen بيتكوّن لما metal زي الـ iron يتفاعل مع dilute acid. الـ metal oxide بيدّي salt ومية بس.","feedback":"الفكرة الغلط: إن الـ metal oxide بيدّي hydrogen مع الـ acid."}},"explanation":"الـ FeO هو black powder، و insoluble in water. وبيتأكسد بسهولة في الهوا السخن. ومع الـ dilute acids بيدّي iron (II) salt و water: $\\ce{FeO + H2SO4 -> FeSO4 + H2O}$. الـ iron بيفضل +2، ومفيش gas بيطلع."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":17,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-fe2o3-3","kind":"question","version":1,"ord":511,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-fe2o3","concepts":[{"concept_id":"fe.oxide-fe2o3","role":"primary"},{"concept_id":"fe.oxide-feo","role":"secondary"}],"title":"chem-s3-en.question-fe.oxide-fe2o3-3","payload":{"stem":"FeO is added to dilute sulphuric acid, and $\\ce{Fe2O3}$ is heated with concentrated sulphuric acid. Which statement compares the two reactions correctly?","tags":["exam-style","compare","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"FeO gives iron (II) sulphate and $\\ce{Fe2O3}$ gives iron (III) sulphate; both also give water and no gas.","correct":true},{"id":"b","text":"Both give iron (III) sulphate, because acids oxidize iron.","correct":false},{"id":"c","text":"Both give a salt and hydrogen gas.","correct":false},{"id":"d","text":"FeO gives iron (III) sulphate because it is easily oxidized; $\\ce{Fe2O3}$ gives iron (III) sulphate too.","correct":false}],"book_ref":"Ch.1 'IRON Oxides' 2-Iron (III) oxide, pp.22-23; Ch.1 'IRON Oxides' 1-Iron (II) oxide, p.22; exam form: compare","difficulty":3,"concept_ids":["fe.oxide-fe2o3","fe.oxide-feo"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: an oxide with an acid gives a salt and water, and iron keeps its oxidation state: FeO (+2) gives $\\ce{FeSO4}$, $\\ce{Fe2O3}$ (+3) gives $\\ce{Fe2(SO4)3}$."},"b":{"why":"Iron is +2 in FeO, and the reaction of an oxide with an acid does not change iron's oxidation state.","feedback":"Misconception: Acids oxidize iron oxides to iron (III)."},"c":{"why":"Hydrogen comes from a metal displacing it. These are oxides, and an oxide with an acid gives a salt and water.","feedback":"Misconception: Oxides give hydrogen with acids."},"d":{"why":"FeO is oxidized by hot air, but this reaction has only an acid and no air, so iron stays +2.","feedback":"Misconception: FeO is oxidized by acids as it is by hot air."}},"explanation":"An oxide and an acid give a salt and water, with no gas. Iron keeps its oxidation state. FeO (+2) gives $\\ce{FeSO4}$. $\\ce{Fe2O3}$ (+3) gives $\\ce{Fe2(SO4)3}$ with the hot concentrated acid. FeO is easily oxidized by hot air, not by a dilute acid."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ oxide مع الـ acid بيدّوا salt ومية، والـ iron بيحتفظ بالـ oxidation state بتاعه: الـ FeO (+2) بيدّي $\\ce{FeSO4}$، والـ $\\ce{Fe2O3}$ (+3) بيدّي $\\ce{Fe2(SO4)3}$."},"b":{"why":"الـ iron في الـ FeO بيبقى +2، وتفاعل الـ oxide مع الـ acid مش بيغيّر الـ oxidation state بتاع الـ iron.","feedback":"الفكرة الغلط: إن الـ acids بتأكسد الـ iron oxides وتحوّلها لـ iron (III)."},"c":{"why":"الـ hydrogen بيطلع لما metal يحل محله في الـ acid، ودول oxides مش metals، فبيدّوا salt ومية.","feedback":"الفكرة الغلط: إن الـ oxides بتدّي hydrogen مع الـ acids."},"d":{"why":"الـ FeO بيتأكسد (oxidized) بالهوا السخن، وفي التفاعل ده مفيش هوا، فيه acid بس.","feedback":"الفكرة الغلط: إن الـ FeO بيتأكسد بالـ acids زي ما بيتأكسد بالهوا السخن."}},"explanation":"الـ oxide مع الـ acid بيدّوا salt ومية، من غير أي غاز. والـ iron بيحتفظ بالـ oxidation state بتاعه. الـ FeO (+2) بيدّي $\\ce{FeSO4}$. والـ $\\ce{Fe2O3}$ (+3) بيدّي $\\ce{Fe2(SO4)3}$ مع الـ acid المركّز السخن. الـ FeO بيتأكسد بسهولة بالهوا السخن، مش بالـ dilute acid."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":18,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-fe3o4-3","kind":"question","version":2,"ord":512,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-fe3o4","concepts":[{"concept_id":"fe.oxide-fe3o4","role":"primary"},{"concept_id":"fe.conversions","role":"secondary"}],"title":"chem-s3-en.question-fe.oxide-fe3o4-3","payload":{"stem":"Carbon monoxide is passed over heated iron (III) oxide at 250 °C. Write the balanced equation of the reaction, with the condition over the arrow.","tags":["exam-style","equation","conditions"],"type":"short","bloom":"apply","answer":"$\\ce{3Fe2O3(s) + CO(g) ->[230-300\\,^{\\circ}C] 2Fe3O4(s) + CO2(g)}$","book_ref":"Ch.1 'IRON Oxides' 3-The black oxide (magnetic iron oxide), pp.23-24","difficulty":3,"concept_ids":["fe.oxide-fe3o4","fe.conversions"],"est_seconds":75},"layer":{"explanation":"At 230–300 °C, CO removes only a little oxygen: $\\ce{Fe2O3}$ becomes $\\ce{Fe3O4}$. 250 °C lies in this range, so write 230–300 °C (or 250 °C). 3 $\\ce{Fe2O3}$ hold 6 Fe and 9 O. 2 $\\ce{Fe3O4}$ hold 6 Fe and 8 O. The ninth O joins CO as $\\ce{CO2}$. Most likely wrong answer: iron as the product. That needs higher than 700 °C."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"عند 230–300 °C الـ CO بيشيل يدوب شوية oxygen: الـ $\\ce{Fe2O3}$ بيتحوّل لـ $\\ce{Fe3O4}$. والـ 250 °C جوه المدى ده، فاكتب 230–300 °C (أو 250 °C). الـ 3 $\\ce{Fe2O3}$ فيهم 6 Fe و9 O. والـ 2 $\\ce{Fe3O4}$ فيهم 6 Fe و8 O. الـ O التاسعة بتروح للـ CO وتعمل $\\ce{CO2}$. أشهر غلطة: إنك تكتب iron كناتج. ده محتاج أعلى من 700 °C."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":19,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":24,"page_to":24,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.conversions-3","kind":"question","version":2,"ord":513,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.conversions","concepts":[{"concept_id":"fe.conversions","role":"primary"}],"title":"chem-s3-en.question-fe.conversions-3","payload":{"stem":"Carbon monoxide is passed over heated $\\ce{Fe2O3}$, and the solid left is FeO. In which temperature range was the reaction carried out?","tags":["exam-style","choose","conditions"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"400–700 °C","correct":true},{"id":"b","text":"230–300 °C","correct":false},{"id":"c","text":"Higher than 700 °C","correct":false},{"id":"d","text":"Any temperature, because CO always gives the same product","correct":false,"misconception_id":"fe.conversions.mc1"}],"book_ref":"Ch.1 Evaluation Q6 (conversion diagrams), p.26; reactions pp.18, 21-24","difficulty":3,"concept_ids":["fe.conversions"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: with CO, 400–700 °C is the range where the higher oxides are reduced to FeO."},"b":{"why":"In this lowest range, CO removes only a little oxygen, and $\\ce{Fe3O4}$ forms, not FeO.","feedback":"Misconception: The lowest range gives FeO."},"c":{"why":"At the highest temperatures, CO removes all the oxygen, so iron would be left, not FeO.","feedback":"Misconception: Every reduction of $\\ce{Fe2O3}$ stops at FeO."},"d":{"why":"The book does not write one condition for every CO reaction: the blast furnace and the $\\ce{Fe3O4}$ preparation use different temperatures.","feedback":"Misconception: The same reagent always gives the same product."}},"explanation":"With CO, the temperature decides how much oxygen is removed. 230–300 °C: $\\ce{Fe2O3}$ → $\\ce{Fe3O4}$. 400–700 °C: higher oxides → FeO. Higher than 700 °C: $\\ce{Fe2O3}$ → Fe. So FeO points to 400–700 °C."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: مع الـ CO، المدى 400–700 °C هو اللي الـ oxides الأعلى بتتختزل فيه لـ FeO."},"b":{"why":"في المدى ده، اللي هو الأقل، الـ CO بيشيل شوية oxygen بس، والـ oxide اللي بيتكوّن هناك هو $\\ce{Fe3O4}$، مش FeO.","feedback":"الفكرة الغلط: إن أقل مدى حرارة هو اللي بيدي FeO."},"c":{"why":"في أعلى درجات الحرارة، الـ CO بيشيل الـ oxygen كله، فاللي بيفضل هو الـ Fe، مش FeO.","feedback":"الفكرة الغلط: إن أي reduction للـ $\\ce{Fe2O3}$ بيقف عند FeO."},"d":{"why":"الكتاب مش كاتب ظرف واحد لكل تفاعلات الـ CO: الـ blast furnace وتحضير الـ $\\ce{Fe3O4}$ ليهم مديات حرارة مختلفة، والناتج بيختلف معاها.","feedback":"الفكرة الغلط: إن نفس المادة بتدي نفس الناتج دايمًا."}},"explanation":"مع الـ CO، الحرارة هي اللي بتحدد قد إيه oxygen هيتشال. 230–300 °C: $\\ce{Fe2O3}$ → $\\ce{Fe3O4}$. 400–700 °C: الـ oxides الأعلى → FeO. أعلى من 700 °C: $\\ce{Fe2O3}$ → Fe. يبقى الـ FeO بيشاور على 400–700 °C."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":20,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":24,"page_to":24,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-feo-4","kind":"question","version":1,"ord":514,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-feo","concepts":[{"concept_id":"fe.oxide-feo","role":"primary"}],"title":"chem-s3-en.question-fe.oxide-feo-4","payload":{"stem":"Iron (III) oxide is reduced by carbon monoxide at 400–700 °C to iron (II) oxide. Write the balanced equation, with the condition over the arrow.","tags":["exam-style","equation","new-case"],"type":"short","bloom":"apply","answer":"\\ce{Fe2O3(s) + CO(g) ->[400-700\\,^{\\circ}C] 2FeO(s) + CO2(g)}","book_ref":"Ch.1 'IRON Oxides' 1-Iron (II) oxide, p.22","difficulty":3,"concept_ids":["fe.oxide-feo"],"est_seconds":75},"layer":{"explanation":"The book prepares FeO by reducing higher oxides with hydrogen or carbon monoxide at 400–700 °C. $\\ce{Fe2O3}$ holds 2 Fe, so 2 FeO form. 2 FeO keep 2 O; the third O joins CO to give $\\ce{CO2}$. Most likely wrong answer: iron as the product. That needs CO at higher than 700 °C."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الكتاب بيحضّر الـ FeO بإنه يختزل الـ higher oxides بالـ hydrogen أو الـ carbon monoxide عند 400–700 °C. الـ $\\ce{Fe2O3}$ فيه 2 Fe، يبقى بيتكوّن 2 FeO. الـ 2 FeO شايلين 2 O؛ والـ O التالتة بتتحد مع الـ CO وتدّي $\\ce{CO2}$. أشهر إجابة غلط: إن الناتج يبقى iron. ده محتاج CO عند أعلى من 700 °C."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":21,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-fe2o3-4","kind":"question","version":1,"ord":515,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-fe2o3","concepts":[{"concept_id":"fe.oxide-fe2o3","role":"primary"},{"concept_id":"fe.oxide-feo","role":"secondary"}],"title":"chem-s3-en.question-fe.oxide-fe2o3-4","payload":{"stem":"FeO is heated in air. The solid product is then heated with concentrated sulphuric acid. What is the iron compound in the final solution, and what is iron's oxidation state in it?","tags":["exam-style","two-step"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$\\ce{Fe2(SO4)3}$; +3","correct":true},{"id":"b","text":"$\\ce{FeSO4}$; +2","correct":false},{"id":"c","text":"$\\ce{FeSO4}$ and $\\ce{Fe2(SO4)3}$; +2 and +3","correct":false},{"id":"d","text":"$\\ce{FeSO4}$; +2, because the acid reduces iron (III)","correct":false}],"book_ref":"Ch.1 'IRON Oxides' 2-Iron (III) oxide, pp.22-23; Ch.1 'IRON Oxides' 1-Iron (II) oxide, p.22","difficulty":4,"concept_ids":["fe.oxide-fe2o3","fe.oxide-feo"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right: hot air oxidizes FeO to $\\ce{Fe2O3}$, and $\\ce{Fe2O3}$ with hot concentrated $\\ce{H2SO4}$ gives $\\ce{Fe2(SO4)3}$, with iron +3."},"b":{"why":"Hot air oxidizes FeO to iron (III) oxide ($\\ce{Fe2O3}$), and that is the oxide that goes into the acid.","feedback":"Misconception: FeO is unchanged when heated in air."},"c":{"why":"Two salts come from the mixed oxide, but FeO in hot air gives iron (III) oxide ($\\ce{Fe2O3}$), not the mixed oxide.","feedback":"Misconception: FeO in hot air gives $\\ce{Fe3O4}$."},"d":{"why":"Hydrogen reduces iron (III) only when iron metal reacts with a dilute acid. An oxide releases no hydrogen, so iron stays +3.","feedback":"Misconception: An acid reduces iron (III) as the hydrogen from Fe + dilute acid does."}},"explanation":"Step 1: FeO is easily oxidized in hot air: $\\ce{4FeO + O2 ->[\\Delta] 2Fe2O3}$. Step 2: $\\ce{Fe2O3}$ with hot concentrated $\\ce{H2SO4}$ gives iron (III) sulphate and water: $\\ce{Fe2O3 + 3H2SO4 -> Fe2(SO4)3 + 3H2O}$. Iron is +3 in the final salt."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الهوا السخن بيأكسد الـ FeO لـ $\\ce{Fe2O3}$، والـ $\\ce{Fe2O3}$ مع الـ $\\ce{H2SO4}$ المركّز السخن بيدّي $\\ce{Fe2(SO4)3}$، والـ iron فيه +3."},"b":{"why":"الهوا السخن بيأكسد الـ FeO لـ $\\ce{Fe2O3}$، فالـ oxide اللي بيدخل الـ acid هو الـ $\\ce{Fe2O3}$.","feedback":"الفكرة الغلط: إن الـ FeO مابيتغيّرش لما يتسخّن في الهوا."},"c":{"why":"الـ salts الاتنين بييجوا من الـ oxide المختلط (mixed oxide)، لكن الـ FeO في الهوا السخن بيدّي $\\ce{Fe2O3}$، مش الـ oxide المختلط.","feedback":"الفكرة الغلط: إن الـ FeO في الهوا السخن بيدّي $\\ce{Fe3O4}$."},"d":{"why":"الـ hydrogen بيختزل الـ iron (III) لما الـ iron metal يتفاعل مع dilute acid، لكن الـ oxide مع الـ acid مابيطلّعش hydrogen.","feedback":"الفكرة الغلط: إن الـ acid بيختزل الـ iron (III) زي ما الـ hydrogen اللي طالع من Fe + dilute acid بيعمل."}},"explanation":"الخطوة 1: الـ FeO بيتأكسد (oxidized) بسهولة في الهوا السخن: $\\ce{4FeO + O2 ->[\\Delta] 2Fe2O3}$. الخطوة 2: الـ $\\ce{Fe2O3}$ مع الـ $\\ce{H2SO4}$ المركّز السخن بيدّي iron (III) sulphate ومية: $\\ce{Fe2O3 + 3H2SO4 -> Fe2(SO4)3 + 3H2O}$. والـ iron في الـ salt اللي في الآخر بيبقى +3."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":22,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-fe3o4-4","kind":"question","version":1,"ord":516,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-fe3o4","concepts":[{"concept_id":"fe.oxide-fe3o4","role":"primary"}],"title":"chem-s3-en.question-fe.oxide-fe3o4-4","payload":{"stem":"Consider the following statements about magnetic iron oxide, $\\ce{Fe3O4}$: (I) It is a strong magnet. (II) When heated in air, it is oxidized to iron (III) oxide. (III) It is known naturally as hematite. Which statements are correct?","tags":["exam-style","correct-statements"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"(I) and (II) only","correct":true},{"id":"b","text":"(I) and (III) only","correct":false},{"id":"c","text":"(II) and (III) only","correct":false},{"id":"d","text":"(I), (II) and (III)","correct":false}],"book_ref":"Ch.1 'IRON Oxides' 3-The black oxide (magnetic iron oxide), pp.23-24","difficulty":3,"concept_ids":["fe.oxide-fe3o4"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: $\\ce{Fe3O4}$ is a strong magnet and is oxidized to $\\ce{Fe2O3}$ when heated in air; it is known naturally as magnetite, not hematite."},"b":{"why":"Hematite is the red ore; $\\ce{Fe3O4}$ is the black magnetic ore, magnetite. Heating in air does oxidize $\\ce{Fe3O4}$ to iron (III) oxide ($\\ce{Fe2O3}$).","feedback":"Misconception: $\\ce{Fe3O4}$ is hematite."},"c":{"why":"The magnetic oxide is known naturally as magnetite, not hematite, and $\\ce{Fe3O4}$ is a strong magnet.","feedback":"Misconception: $\\ce{Fe3O4}$ is hematite and is not magnetic."},"d":{"why":"Statement (III) swaps two ores: hematite is $\\ce{Fe2O3}$, while $\\ce{Fe3O4}$ is magnetite.","feedback":"Misconception: $\\ce{Fe3O4}$ is hematite."}},"explanation":"(I) is correct: $\\ce{Fe3O4}$ is a strong magnet. (II) is correct: $\\ce{2Fe3O4 + 1/2O2 ->[\\Delta] 3Fe2O3}$; its iron (II) part is oxidized to iron (III). (III) is wrong: $\\ce{Fe3O4}$ is known naturally as magnetite. Hematite is $\\ce{Fe2O3}$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ $\\ce{Fe3O4}$ strong magnet، ولما يتسخن في الهوا بيتأكسد لـ $\\ce{Fe2O3}$؛ واسمه في الطبيعة magnetite، مش hematite."},"b":{"why":"الـ hematite هو الـ ore الأحمر ($\\ce{Fe2O3}$)، أما الـ $\\ce{Fe3O4}$ فهو الـ magnetite الأسود الـ magnetic. والتسخين في الهوا بيأكسد الـ $\\ce{Fe3O4}$ لـ $\\ce{Fe2O3}$.","feedback":"الفكرة الغلط: إن الـ $\\ce{Fe3O4}$ هو الـ hematite."},"c":{"why":"الاسم الطبيعي للـ oxide الـ magnetic هو الـ magnetite، والـ $\\ce{Fe3O4}$ فعلًا strong magnet.","feedback":"الفكرة الغلط: إن الـ $\\ce{Fe3O4}$ هو الـ hematite ومش magnetic."},"d":{"why":"عبارة (III) بتبدّل بين 2 ores: الـ hematite هو الـ $\\ce{Fe2O3}$، مش الـ $\\ce{Fe3O4}$.","feedback":"الفكرة الغلط: إن الـ $\\ce{Fe3O4}$ هو الـ hematite."}},"explanation":"(I) صح: الـ $\\ce{Fe3O4}$ strong magnet. (II) صح: $\\ce{2Fe3O4 + 1/2O2 ->[\\Delta] 3Fe2O3}$؛ جزء الـ iron (II) اللي فيه بيتأكسد لـ iron (III). (III) غلط: الـ $\\ce{Fe3O4}$ اسمه في الطبيعة magnetite. أما الـ hematite فهو $\\ce{Fe2O3}$."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":23,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":24,"page_to":24,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.conversions-4","kind":"question","version":2,"catalog_version":1,"ord":517,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.conversions","concepts":[{"concept_id":"fe.conversions","role":"primary"},{"concept_id":"fe.oxide-fe2o3","role":"secondary"},{"concept_id":"fe.reactions-nonmetals","role":"secondary"}],"title":"chem-s3-en.question-fe.conversions-4","payload":{"stem":"Study the diagram. Identify substances X, Y and Z.","tags":["exam-style","diagram","identify"],"type":"mcq","bloom":"analyze","figure":{"root":"f","elements":{"f":{"type":"FlowDiagram","props":{"edges":[{"to":"x","from":"fe","label":"(1) + $\\ce{Cl2}$, heat"},{"to":"y","from":"x","label":"(2) + $\\ce{NH4OH}$(aq)"},{"to":"o","from":"y","label":"(3) above 200 °C"},{"to":"z","from":"o","label":"(4) + $\\ce{H2}$, 400–700 °C"}],"nodes":[{"id":"fe","label":"Fe"},{"id":"x","label":"X"},{"id":"y","label":"Y"},{"id":"o","label":"$\\ce{Fe2O3}$"},{"id":"z","label":"Z"}],"layout":"horizontal","caption":"Iron conversions"},"children":[]}}},"choices":[{"id":"a","text":"X = $\\ce{FeCl3}$, Y = $\\ce{Fe(OH)3}$, Z = FeO","correct":true},{"id":"b","text":"X = $\\ce{FeCl2}$, Y = $\\ce{Fe(OH)2}$, Z = FeO","correct":false,"misconception_id":"fe.reactions-nonmetals.mc1"},{"id":"c","text":"X = $\\ce{FeCl3}$, Y = $\\ce{Fe(OH)3}$, Z = Fe","correct":false},{"id":"d","text":"X = $\\ce{FeCl3}$, Y = $\\ce{Fe(OH)3}$, Z = $\\ce{Fe3O4}$","correct":false}],"book_ref":"Ch.1 Evaluation Q6 (conversion diagrams), p.26; reactions pp.18, 21-24; preparation of iron (III) oxide, pp.22-23","difficulty":4,"concept_ids":["fe.conversions","fe.oxide-fe2o3","fe.reactions-nonmetals"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Right: chlorine takes iron to iron (III) chloride, the alkali precipitates $\\ce{Fe(OH)3}$, heating gives $\\ce{Fe2O3}$, and hydrogen at 400–700 °C reduces it to FeO."},"b":{"why":"Chlorine gas forms no hydrogen. As a strong oxidizing agent, it takes iron to iron (III), giving $\\ce{FeCl3}$, not $\\ce{FeCl2}$.","feedback":"Misconception: Fe + $\\ce{Cl2}$ gives $\\ce{FeCl2}$."},"c":{"why":"Reduction at 400–700 °C does not remove all the oxygen: it gives FeO, not iron.","feedback":"Misconception: Hydrogen at 400–700 °C removes all the oxygen."},"d":{"why":"$\\ce{Fe3O4}$ forms with CO at 230–300 °C, but arrow (4) is at 400–700 °C.","feedback":"Misconception: Mixing up the temperature ranges."}},"explanation":"(1) $\\ce{2Fe + 3Cl2 -> 2FeCl3}$: X is iron (III) chloride. (2) An alkali precipitates reddish brown iron (III) hydroxide: Y is $\\ce{Fe(OH)3}$. (3) Above 200 °C, $\\ce{2Fe(OH)3 -> Fe2O3 + 3H2O}$. (4) $\\ce{Fe2O3 + H2 ->[400-700\\,^{\\circ}C] 2FeO + H2O}$: Z is FeO."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ chlorine بيوصّل الـ iron لـ iron (III) chloride، والـ alkali بيرسّب $\\ce{Fe(OH)3}$، والتسخين بيدي $\\ce{Fe2O3}$، والـ hydrogen عند 400–700 °C بيختزله لـ FeO."},"b":{"why":"غاز الـ Chlorine oxidizing agent قوي، فبيوصّل الـ iron لـ $\\ce{FeCl3}$، مش $\\ce{FeCl2}$.","feedback":"الفكرة الغلط: إن Fe + $\\ce{Cl2}$ بيدي $\\ce{FeCl2}$."},"c":{"why":"الـ reduction عند 400–700 °C مابيشيلش الـ oxygen كله؛ الناتج هناك FeO، مش iron.","feedback":"الفكرة الغلط: إن الـ hydrogen عند 400–700 °C بيشيل الـ oxygen كله."},"d":{"why":"الـ $\\ce{Fe3O4}$ بيتكوّن مع الـ CO عند 230–300 °C، والمدى اللي على السهم (4) هو 400–700 °C، وده بيدّي ناتج تاني.","feedback":"الفكرة الغلط: إنك تلخبط بين مديات الحرارة."}},"explanation":"(1) $\\ce{2Fe + 3Cl2 -> 2FeCl3}$: يعني X هو iron (III) chloride. (2) الـ alkali بيرسّب iron (III) hydroxide لونه بني محمر: يعني Y هو $\\ce{Fe(OH)3}$. (3) فوق 200 °C: $\\ce{2Fe(OH)3 -> Fe2O3 + 3H2O}$. (4) $\\ce{Fe2O3 + H2 ->[400-700\\,^{\\circ}C] 2FeO + H2O}$: يعني Z هو FeO."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":24,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-fe3o4-5","kind":"question","version":1,"ord":518,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.oxide-fe3o4","concepts":[{"concept_id":"fe.oxide-fe3o4","role":"primary"},{"concept_id":"fe.oxide-fe2o3","role":"secondary"},{"concept_id":"fe.oxide-feo","role":"secondary"}],"title":"chem-s3-en.question-fe.oxide-fe3o4-5","payload":{"stem":"Compare the three iron oxides: classify each description under the oxide it describes.","tags":["exam-style","compare","classify"],"type":"classify","bloom":"understand","answer":{"feo":["i1","i2"],"fe2o3":["i3","i4"],"fe3o4":["i5","i6","i7"]},"choices":[{"id":"i1","text":"Prepared by heating iron (II) oxalate in the absence of air"},{"id":"i2","text":"Gives only an iron (II) salt and water with dilute acids"},{"id":"i3","text":"Used in red pigments in paints"},{"id":"i4","text":"Prepared by heating iron (II) sulphate"},{"id":"i5","text":"A strong magnet, known naturally as magnetite"},{"id":"i6","text":"Gives iron (II) and iron (III) salts with hot concentrated acids"},{"id":"i7","text":"Prepared by reducing $\\ce{Fe2O3}$ with CO at 230–300 °C"}],"book_ref":"Ch.1 'IRON Oxides' 1-3, pp.22-24; exam form: compare","categories":[{"id":"feo","label":"FeO"},{"id":"fe2o3","label":"$\\ce{Fe2O3}$"},{"id":"fe3o4","label":"$\\ce{Fe3O4}$"}],"difficulty":3,"concept_ids":["fe.oxide-fe3o4","fe.oxide-feo","fe.oxide-fe2o3"],"est_seconds":120},"layer":{"choices":{"i1":{"why":"Air is kept out because the product, the oxide holding iron at +2 only, is easily oxidized.","feedback":"Misconception: Any iron oxide can be made from the oxalate."},"i2":{"why":"An iron (II) salt only means the oxide holds iron in the +2 state only.","feedback":"Misconception: The mixed oxide gives only an iron (II) salt."},"i3":{"why":"FeO is black; the oxide that colours paints red holds iron at +3.","feedback":"Misconception: FeO is red."},"i4":{"why":"Heating oxidizes iron here, from +2 to +3, so the product holds iron at +3 only.","feedback":"Misconception: Heating iron (II) sulphate gives FeO."},"i5":{"why":"Magnetite, the black magnetic ore, is the mixed oxide of iron (II) and iron (III), not hematite.","feedback":"Misconception: Hematite is the magnetic ore."},"i6":{"why":"Two salts mean two oxidation states, so the oxide must contain both iron (II) and iron (III).","feedback":"Misconception: $\\ce{Fe2O3}$ gives two salts because it has two Fe atoms."},"i7":{"why":"At this low range, CO removes only a little oxygen, so the product is only one step down from iron (III) oxide ($\\ce{Fe2O3}$): the magnetic mixed oxide.","feedback":"Misconception: CO at any temperature gives FeO."}},"explanation":"FeO: prepared from iron (II) oxalate in absence of air. With dilute acids, it gives only an iron (II) salt and water. $\\ce{Fe2O3}$: red pigments in paints; prepared by heating iron (II) sulphate. $\\ce{Fe3O4}$: a strong magnet (magnetite); gives two salts with hot concentrated acids; made from $\\ce{Fe2O3}$ and CO at 230–300 °C."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"i1":{"why":"الهوا بيتمنع هنا لأن الناتج بيتأكسد بسهولة في الهوا، ودي صفة الـ oxide اللي فيه iron عند +2 بس.","feedback":"الفكرة الغلط: إن أي iron oxide ممكن يتحضّر من الـ oxalate."},"i2":{"why":"iron (II) salt لوحده معناه إن الـ oxide فيه iron في الحالة +2 تحديدًا، مش الـ mixed oxide اللي بيدّي ملحين.","feedback":"الفكرة الغلط: إن الـ mixed oxide بيدّي iron (II) salt لوحده."},"i3":{"why":"الـ FeO لونه أسود. اللون الأحمر اللي في البويات بييجي من الـ oxide اللي فيه iron عند +3.","feedback":"الفكرة الغلط: إن الـ FeO لونه أحمر."},"i4":{"why":"التسخين هنا بيأكسد الـ iron، من +2 لـ +3، فالناتج oxide فيه iron عند +3 تحديدًا، مش FeO.","feedback":"الفكرة الغلط: إن تسخين الـ iron (II) sulphate بيدّي FeO."},"i5":{"why":"الـ hematite مش هو الـ ore الأسود الـ magnetic؛ الـ ore ده هو الـ magnetite.","feedback":"الفكرة الغلط: إن الـ hematite هو الـ ore الـ magnetic."},"i6":{"why":"ملحين يعني 2 oxidation states، ووجود 2 Fe atoms في الـ formula مش معناه 2 oxidation states.","feedback":"الفكرة الغلط: إن الـ $\\ce{Fe2O3}$ بيدّي ملحين عشان فيه 2 Fe atoms."},"i7":{"why":"في المدى الواطي ده، الـ CO بيشيل يدوب شوية oxygen من الـ $\\ce{Fe2O3}$، فبيدّي الـ oxide اللي بعده بخطوة لتحت، مش FeO.","feedback":"الفكرة الغلط: إن الـ CO عند أي درجة حرارة بيدّي FeO."}},"explanation":"الـ FeO: بيتحضّر من الـ iron (II) oxalate في غياب الهوا. ومع الـ dilute acids بيدّي iron (II) salt لوحده ومية. الـ $\\ce{Fe2O3}$: بيستخدم في الصبغات الحمرا في البويات؛ وبيتحضّر بتسخين الـ iron (II) sulphate. الـ $\\ce{Fe3O4}$: strong magnet (magnetite)؛ بيدّي ملحين مع الـ hot concentrated acids؛ وبيتعمل من الـ $\\ce{Fe2O3}$ والـ CO عند 230–300 °C."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":25,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":24,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.conversions-5","kind":"question","version":2,"catalog_version":1,"ord":519,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.conversions","concepts":[{"concept_id":"fe.conversions","role":"primary"}],"title":"chem-s3-en.question-fe.conversions-5","payload":{"stem":"Study the diagram. Which choice gives conditions A and B?","tags":["exam-style","diagram","conditions"],"type":"mcq","bloom":"apply","figure":{"root":"f","elements":{"f":{"type":"FlowDiagram","props":{"edges":[{"to":"h","from":"m","label":"A"},{"to":"fe","from":"h","label":"B"}],"nodes":[{"id":"m","label":"$\\ce{Fe3O4}$"},{"id":"h","label":"$\\ce{Fe2O3}$"},{"id":"fe","label":"Fe"}],"layout":"horizontal","caption":"Two conversions"},"children":[]}}},"choices":[{"id":"a","text":"A: heating in air; B: CO, higher than 700 °C","correct":true},{"id":"b","text":"A: $\\ce{H2}$ at 400–700 °C; B: CO, higher than 700 °C","correct":false},{"id":"c","text":"A: heating in air; B: CO at 230–300 °C","correct":false},{"id":"d","text":"A: heating in absence of air; B: CO, higher than 700 °C","correct":false,"misconception_id":"fe.conversions.mc2"}],"book_ref":"Ch.1 Evaluation Q6 (conversion diagrams), p.26; reactions pp.18, 21-24; Evaluation Q6 (b), p.26","difficulty":3,"concept_ids":["fe.conversions"],"est_seconds":60},"layer":{"choices":{"a":{"why":"Right: heating in air adds oxygen to turn $\\ce{Fe3O4}$ into $\\ce{Fe2O3}$, and CO at higher than 700 °C removes all the oxygen to give iron."},"b":{"why":"$\\ce{Fe3O4}$ → $\\ce{Fe2O3}$ gains oxygen, and hydrogen removes oxygen; it does not add it.","feedback":"Misconception: Confusing oxidation with reduction."},"c":{"why":"At 230–300 °C, CO removes only a little oxygen and gives $\\ce{Fe3O4}$, not iron.","feedback":"Misconception: CO gives iron at any temperature."},"d":{"why":"Without air, there is no source of the extra oxygen that $\\ce{Fe3O4}$ needs to become $\\ce{Fe2O3}$.","feedback":"Misconception: Ignoring 'absence of air' and 'hot air' conditions."}},"explanation":"Step A adds oxygen, so it is an oxidation: $\\ce{2Fe3O4 + 1/2O2 ->[\\Delta] 3Fe2O3}$, by heating in air. Step B removes all the oxygen: $\\ce{Fe2O3 + 3CO ->[\\text{higher than }700\\,^{\\circ}C] 2Fe + 3CO2}$. Lower temperatures with CO give $\\ce{Fe3O4}$ or FeO, not iron."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: التسخين في الهوا بيضيف oxygen فيحوّل الـ $\\ce{Fe3O4}$ لـ $\\ce{Fe2O3}$، والـ CO عند أعلى من 700 °C بيشيل الـ oxygen كله فيدي iron."},"b":{"why":"الـ $\\ce{Fe3O4}$ → $\\ce{Fe2O3}$ بيكسب oxygen، والـ hydrogen بيشيل الـ oxygen، مش بيضيفه.","feedback":"الفكرة الغلط: إنك تلخبط بين الـ oxidation والـ reduction."},"c":{"why":"عند 230–300 °C، الـ CO بيشيل يدوب شوية oxygen، فالناتج بيبقى $\\ce{Fe3O4}$، مش iron.","feedback":"الفكرة الغلط: إن الـ CO بيدي iron عند أي درجة حرارة."},"d":{"why":"من غير هوا، مفيش مصدر للـ oxygen الزيادة اللي الـ $\\ce{Fe3O4}$ محتاجه عشان يبقى $\\ce{Fe2O3}$.","feedback":"الفكرة الغلط: إنك تتجاهل ظرف «في غياب الهوا» وظرف «في الهوا السخن»."}},"explanation":"الخطوة A بتضيف oxygen، يبقى دي oxidation: $\\ce{2Fe3O4 + 1/2O2 ->[\\Delta] 3Fe2O3}$، بالتسخين في الهوا. الخطوة B بتشيل الـ oxygen كله: $\\ce{Fe2O3 + 3CO ->[\\text{higher than }700\\,^{\\circ}C] 2Fe + 3CO2}$. والحرارة الأقل مع الـ CO بتدي $\\ce{Fe3O4}$ أو FeO، مش iron."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":26,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":24,"page_to":24,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.reaction-dilute-acids-6","kind":"question","version":1,"ord":520,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.reaction-dilute-acids","concepts":[{"concept_id":"fe.reaction-dilute-acids","role":"primary"},{"concept_id":"fe.oxide-fe2o3","role":"secondary"}],"title":"chem-s3-en.question-fe.reaction-dilute-acids-6","payload":{"stem":"What happens when iron reacts with dilute sulphuric acid, and the iron salt formed is then dried and heated strongly? Write the equations.","tags":["mixed","retrieval","what-happens"],"type":"short","bloom":"apply","answer":"Key points: (1) $\\ce{Fe + H2SO4 ->[(dil)] FeSO4 + H2}$: iron (II) sulphate and hydrogen gas. (2) $\\ce{2FeSO4 ->[\\Delta] Fe2O3 + SO2 + SO3}$: iron (III) oxide, sulphur dioxide and sulphur trioxide.","book_ref":"Ch.1 'Chemical Properties' 4, p.21; iron (III) oxide preparation 2, p.23; exam form: what happens when","difficulty":3,"concept_ids":["fe.reaction-dilute-acids","fe.oxide-fe2o3"],"est_seconds":120},"layer":{"explanation":"Iron displaces hydrogen from the dilute acid and gives iron (II) sulphate. The produced hydrogen keeps iron at +2. Heating iron (II) sulphate strongly gives red iron (III) oxide, $\\ce{SO2}$ and $\\ce{SO3}$. Most likely slip: writing $\\ce{Fe2(SO4)3}$ in step 1."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ iron بياخد مكان الـ hydrogen في الـ dilute acid وبيدي iron (II) sulphate. والـ hydrogen اللي بيطلع بيخلّي الـ iron يفضل عند +2. ولما تسخّن الـ iron (II) sulphate تسخين شديد، بيدي iron (III) oxide الأحمر و$\\ce{SO2}$ و$\\ce{SO3}$. أشهر غلطة: إنك تكتب $\\ce{Fe2(SO4)3}$ في الخطوة الأولى."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":44,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-moment-from-config-6","kind":"question","version":1,"ord":521,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"te.magnetic-moment-from-config","concepts":[{"concept_id":"te.magnetic-moment-from-config","role":"primary"},{"concept_id":"fe.oxide-fe2o3","role":"secondary"},{"concept_id":"fe.oxide-feo","role":"secondary"}],"title":"chem-s3-en.question-te.magnetic-moment-from-config-6","payload":{"stem":"Arrange the following oxides in ascending order according to the magnetic moment of their metal ions (smallest first). ($_{26}$Fe, $_{29}$Cu, $_{30}$Zn)","tags":["mixed","retrieval","arrange"],"type":"order","bloom":"analyze","answer":["x","z","y","w"],"choices":[{"id":"w","text":"$\\ce{Fe2O3}$"},{"id":"x","text":"ZnO"},{"id":"y","text":"FeO"},{"id":"z","text":"CuO"}],"book_ref":"Ch.1 magnetic properties, p.14; iron oxides, pp.22-23","difficulty":4,"concept_ids":["te.magnetic-moment-from-config","fe.oxide-feo","fe.oxide-fe2o3"],"est_seconds":150},"layer":{"choices":{"w":{"why":"Oxide is −2, so iron is +3 here; the 4s electrons leave first, so the ion is 3d⁵ with 5 unpaired electrons."},"x":{"why":"Zinc is +2 here, and its 3d sublevel stays complete in the ion, so it has no unpaired electrons."},"y":{"why":"Iron is +2 here: six 3d electrons in five boxes form one pair, leaving 4 unpaired."},"z":{"why":"Copper is +2 here: nine 3d electrons fill four boxes with pairs and one box with one electron, so 1 is unpaired."}},"explanation":"Count the unpaired electrons in each metal ion. ZnO: $\\ce{Zn^2+}$ is [Ar] $3d^{10}$, 0. CuO: $\\ce{Cu^2+}$ is [Ar] $3d^9$, 1. FeO: $\\ce{Fe^2+}$ is [Ar] $3d^6$, 4. $\\ce{Fe2O3}$: $\\ce{Fe^3+}$ is [Ar] $3d^5$, 5. Order: ZnO < CuO < FeO < $\\ce{Fe2O3}$. Common slip: putting CuO last because it has the most 3d electrons."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"w":{"why":"الـ oxide بـ −2، فالـ iron هنا بـ +3؛ الـ 4s electrons بتمشي الأول، فالـ ion بيبقى 3d⁵ وفيه 5 unpaired electrons."},"x":{"why":"الـ zinc هنا بـ +2، والـ 3d sublevel بتاعه بيفضل كامل في الـ ion، فمفيهوش unpaired electrons."},"y":{"why":"الـ iron هنا بـ +2: ستة 3d electrons في خمس مربعات بيعملوا زوج واحد، ويفضل 4 unpaired."},"z":{"why":"الـ copper هنا بـ +2: تسعة 3d electrons بيملوا أربع مربعات بأزواج ومربع واحد فيه electron واحد، يعني 1 unpaired."}},"explanation":"عدّ الـ unpaired electrons في كل metal ion. الـ ZnO: الـ $\\ce{Zn^2+}$ هو [Ar] $3d^{10}$، يعني 0. الـ CuO: الـ $\\ce{Cu^2+}$ هو [Ar] $3d^9$، يعني 1. الـ FeO: الـ $\\ce{Fe^2+}$ هو [Ar] $3d^6$، يعني 4. الـ $\\ce{Fe2O3}$: الـ $\\ce{Fe^3+}$ هو [Ar] $3d^5$، يعني 5. الترتيب: ZnO < CuO < FeO < $\\ce{Fe2O3}$. غلطة بتتكرر: إنك تحط الـ CuO في الآخر عشان فيه أكتر عدد 3d electrons."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":39,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.roasting-5","kind":"question","version":1,"ord":522,"group_id":"chem-s3-en.ch1.practice.fe-oxides","primary_concept_id":"fe.roasting","concepts":[{"concept_id":"fe.roasting","role":"primary"},{"concept_id":"fe.oxide-feo","role":"secondary"}],"title":"chem-s3-en.question-fe.roasting-5","payload":{"stem":"Write the equations for roasting siderite in air until iron (III) oxide is obtained, and explain why the final product is not FeO.","tags":["mixed","retrieval","equation"],"type":"short","bloom":"understand","answer":"Key points: (1) $\\ce{FeCO3 ->[\\Delta] FeO + CO2}$. (2) $\\ce{2FeO + 1/2O2 ->[\\Delta] Fe2O3}$. (3) Roasting is strong heating in air, and FeO is easily oxidized in hot air, so it changes to $\\ce{Fe2O3}$.","book_ref":"Ch.1 'Roasting', p.17; iron (II) oxide properties, p.22","difficulty":3,"concept_ids":["fe.roasting","fe.oxide-feo"],"est_seconds":120},"layer":{"explanation":"Siderite, iron (II) carbonate, decomposes on heating into FeO and $\\ce{CO2}$. Roasting is strong heating in air. FeO is easily oxidized in hot air, so it becomes $\\ce{Fe2O3}$. Most likely slip: stopping at FeO and forgetting the air."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الـ siderite، يعني iron (II) carbonate، بيتكسّر بالتسخين لـ FeO و $\\ce{CO2}$. والـ roasting تسخين شديد في الهوا. والـ FeO بيحصله oxidation بسهولة في الهوا السخن، فبيتحول لـ $\\ce{Fe2O3}$. أشهر غلطة: إنك توقف عند الـ FeO وتنسى الهوا."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":64,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":17,"page_to":17,"section_key":"ch1.iron.dressing","section_title":"Ore dressing","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Ore dressing"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.first-series-elements-5","kind":"question","version":1,"ord":526,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"te.first-series-elements","concepts":[{"concept_id":"te.first-series-elements","role":"primary"},{"concept_id":"te.ion-configuration","role":"secondary"},{"concept_id":"te.uses-fe-co","role":"secondary"}],"title":"chem-s3-en.question-te.first-series-elements-5","payload":{"stem":"Element X is in the first transition series. Its ion $\\ce{X^3+}$ has a half-filled 3d sublevel. Which choice identifies X and gives one of its uses? ($_{24}$Cr, $_{25}$Mn, $_{26}$Fe, $_{27}$Co)","tags":["mixed","two-step"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"Iron; a catalyst in the manufacture of ammonia by the Haber-Bosch method","correct":true},{"id":"b","text":"Manganese; ferromanganese alloy for railway tracks","correct":false},{"id":"c","text":"Chromium; metal plating and leather tanning","correct":false},{"id":"d","text":"Cobalt; cobalt-60 for food preserving","correct":false}],"book_ref":"Ch.1 uses of iron, pp.6-7; ion configurations, p.9","difficulty":4,"concept_ids":["te.first-series-elements","te.uses-fe-co","te.ion-configuration"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Correct! $\\ce{Fe^3+}$ is [Ar] $3d^5$, a half-filled 3d sublevel, so X is iron, and the book lists iron as a catalyst in the manufacture of ammonia by the Haber-Bosch method."},"b":{"why":"Mn has 7 electrons beyond [Ar]; after it loses three, four 3d electrons are left, so its 3d is not half-filled.","feedback":"Misconception: $\\ce{Mn^3+}$ is $3d^5$ (mixing it up with $\\ce{Mn^2+}$)."},"c":{"why":"The Cr atom is $3d^5$, but after it loses three electrons, three 3d electrons remain, so its 3d is not half-filled.","feedback":"Misconception: The ion keeps the atom's $3d^5$."},"d":{"why":"Co has 9 electrons beyond [Ar]; after it loses three, six 3d electrons remain, which is not half-filled.","feedback":"Misconception: Counting the electrons wrongly."}},"explanation":"A half-filled 3d sublevel is $3d^5$. $\\ce{X^3+}$ has lost three electrons, so the atom has 8 electrons beyond [Ar]: [Ar] $4s^2\\,3d^6$. That is iron ($_{26}$Fe). Iron is used as a catalyst in the Haber-Bosch method. It is also used in the Fischer-Tropsch method."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! الـ $\\ce{Fe^3+}$ هو [Ar] $3d^5$، يعني 3d sublevel نصه مليان، يبقى X هو الـ iron، والكتاب بيقول إن الـ iron بيتستخدم catalyst في تحضير الـ ammonia بالـ Haber-Bosch method."},"b":{"why":"الـ Mn عنده 7 electrons بعد الـ [Ar]؛ بعد ما يخسر تلاتة، بيفضل أربعة 3d electrons، فالـ 3d بتاعه مش half-filled.","feedback":"الفكرة الغلط: إن الـ $\\ce{Mn^3+}$ يبقى $3d^5$ (خلط بينه وبين الـ $\\ce{Mn^2+}$)."},"c":{"why":"ذرة الـ Cr فعلًا $3d^5$، لكن بعد ما تخسر تلات electrons بيفضل تلاتة في الـ 3d، فالـ 3d مش half-filled.","feedback":"الفكرة الغلط: إن الـ ion بيحتفظ بالـ $3d^5$ اللي في الذرة."},"d":{"why":"الـ Co عنده 9 electrons بعد الـ [Ar]؛ بعد ما يخسر تلاتة، بيفضل ستة 3d electrons، وده مش half-filled.","feedback":"الفكرة الغلط: غلط في عدّ الـ electrons."}},"explanation":"الـ 3d sublevel الـ half-filled معناه $3d^5$. الـ $\\ce{X^3+}$ خسر تلات electrons، يبقى الذرة فيها 8 electrons بعد الـ [Ar]: [Ar] $4s^2\\,3d^6$. ده الـ iron ($_{26}$Fe). والـ iron بيتستخدم catalyst في الـ Haber-Bosch method، وبيتستخدم كمان في الـ Fischer-Tropsch method."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":64,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":6,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":9,"page_to":9,"section_key":"ch1.config.ex-fe-mn","section_title":"Iron (II) to iron (III) versus Mn (II)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Iron (II) to iron (III) versus Mn (II)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.uses-cu-zn-4","kind":"question","version":1,"ord":527,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"te.uses-cu-zn","concepts":[{"concept_id":"te.uses-cu-zn","role":"primary"},{"concept_id":"te.uses-ni","role":"secondary"},{"concept_id":"te.uses-sc-ti","role":"secondary"}],"title":"chem-s3-en.question-te.uses-cu-zn-4","payload":{"stem":"Match each transition element in column (A) with one of its uses in column (B).","tags":["mixed","retrieval","match"],"type":"match","bloom":"remember","answer":[["l1","r5"],["l2","r4"],["l3","r3"],["l4","r2"],["l5","r1"]],"choices":[{"id":"l1","text":"Scandium"},{"id":"l2","text":"Titanium"},{"id":"l3","text":"Nickel"},{"id":"l4","text":"Copper"},{"id":"l5","text":"Zinc"},{"id":"r1","text":"Galvanizing other metals to protect them from rusting"},{"id":"r2","text":"Electric cables"},{"id":"r3","text":"A catalyst in the hydrogenation of oils"},{"id":"r4","text":"Dental implants and artificial joints"},{"id":"r5","text":"A light, very hard alloy with aluminum for MiG fighter jets"}],"book_ref":"Ch.1 economic importance of the first transition elements, pp.5-7; exam form: match columns","difficulty":2,"concept_ids":["te.uses-cu-zn","te.uses-ni","te.uses-sc-ti"],"est_seconds":75},"layer":{"choices":{"l1":{"why":"Adding a little scandium to aluminum gives a light, very hard alloy used for MiG fighter jets."},"l2":{"why":"Titanium is used in dental implants and artificial joints because it is inert, so the body does not reject it."},"l3":{"why":"Finely divided nickel is the book's catalyst in the hydrogenation of oils."},"l4":{"why":"Copper is a good conductor of electricity, so it is used in electric cables."},"l5":{"why":"Zinc is used in galvanizing other metals to protect them from rusting."},"r1":{"why":"Galvanizing is zinc's use: a zinc coating protects other metals from rusting."},"r2":{"why":"Electric cables need a good conductor of electricity: copper."},"r3":{"why":"The catalyst of the hydrogenation of oils is finely divided nickel."},"r4":{"why":"Dental implants and artificial joints use titanium, an inert metal the body does not reject."},"r5":{"why":"The light, very hard alloy for MiG fighter jets is aluminum with a little scandium."}},"explanation":"Scandium with aluminum gives a light, very hard alloy for MiG fighter jets. Titanium is used in dental implants and artificial joints, because the body does not reject it. Finely divided nickel is a catalyst in the hydrogenation of oils. Copper is a good conductor, so it is used in electric cables. Zinc is used in galvanizing other metals. Common slip: swapping nickel and zinc, since both protect other metals."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"l1":{"why":"لما تضيف شوية scandium للـ aluminum بيدّوا alloy خفيف وصلب جدًا بيدخل في طيارات الـ MiG المقاتلة."},"l2":{"why":"الـ Titanium بيتستخدم في زراعة الأسنان والمفاصل الصناعية عشان هو inert، فالجسم مابيرفضوش."},"l3":{"why":"الـ finely divided nickel هو الـ catalyst اللي في الكتاب للـ hydrogenation of oils."},"l4":{"why":"الـ Copper موصّل كويس للكهربا، فبيتعمل منه الكابلات الكهربا."},"l5":{"why":"الـ Zinc بيتعمل بيه galvanizing للـ metals التانية عشان يحميها من الصدأ."},"r1":{"why":"الـ galvanizing ده استخدام الـ zinc: طبقة zinc بتحمي الـ metals التانية من الصدأ."},"r2":{"why":"الكابلات الكهربا محتاجة موصّل كويس للكهربا: الـ copper."},"r3":{"why":"الـ catalyst بتاع الـ hydrogenation of oils هو الـ finely divided nickel."},"r4":{"why":"زراعة الأسنان والمفاصل الصناعية بيستخدموا الـ titanium، metal inert الجسم مابيرفضوش."},"r5":{"why":"الـ alloy الخفيف والصلب جدًا بتاع طيارات الـ MiG هو الـ aluminum مع شوية scandium."}},"explanation":"الـ Scandium مع الـ aluminum بيدّوا alloy خفيف وصلب جدًا بيدخل في طيارات الـ MiG المقاتلة. الـ Titanium بيتستخدم في زراعة الأسنان والمفاصل الصناعية، عشان الجسم مابيرفضوش. الـ nickel المجزّأ لحبيبات ناعمة بيشتغل catalyst في الـ hydrogenation of oils. الـ Copper موصّل كويس، فبيتعمل منه الكابلات الكهربا. والـ Zinc بيتعمل بيه galvanizing للـ metals التانية. غلطة بتتكرر: إنك تبدّل الـ nickel والـ zinc، عشان الاتنين بيحموا metals تانية."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":81,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":5,"page_to":5,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":7,"page_to":7,"section_key":"ch1.first-series.uses","section_title":"Economic importance of the elements","section_path":["Transition Elements","The First Transition Series","Economic importance of the elements"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.definition-applied-5","kind":"question","version":1,"ord":528,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"te.definition-applied","concepts":[{"concept_id":"te.definition-applied","role":"primary"}],"title":"chem-s3-en.question-te.definition-applied-5","payload":{"stem":"Classify each element, using the configurations given, as a transition element or not a transition element.","tags":["mixed","classify","new-case"],"type":"classify","bloom":"apply","answer":{"te":["sc","cu","au"],"nte":["zn","ga"]},"choices":[{"id":"sc","text":"$_{21}$Sc: atom [Ar] $4s^2\\,3d^1$; $\\ce{Sc^3+}$: [Ar]"},{"id":"zn","text":"$_{30}$Zn: atom [Ar] $4s^2\\,3d^{10}$; $\\ce{Zn^2+}$: [Ar] $3d^{10}$","misconception_id":"te.definition.mc1"},{"id":"cu","text":"$_{29}$Cu: atom [Ar] $4s^1\\,3d^{10}$; $\\ce{Cu^2+}$ in $\\ce{CuSO4}$: [Ar] $3d^9$"},{"id":"au","text":"$_{79}$Au: atom [Xe] $4f^{14}\\,6s^1\\,5d^{10}$; $\\ce{Au^3+}$: [Xe] $4f^{14}\\,5d^8$"},{"id":"ga","text":"$_{31}$Ga: atom [Ar] $4s^2\\,3d^{10}\\,4p^1$; $\\ce{Ga^3+}$: [Ar] $3d^{10}$"}],"book_ref":"Ch.1 general definition of the transition element and Exercise 1, p.10","categories":[{"id":"te","label":"Transition element"},{"id":"nte","label":"Not a transition element"}],"difficulty":3,"concept_ids":["te.definition-applied"],"est_seconds":120},"layer":{"choices":{"au":{"why":"The atom's 5d is complete, but the +3 state is 5d⁸, incomplete. One such oxidation state is enough.","feedback":"Misconception: Only the atom's configuration matters."},"cu":{"why":"The atom is $3d^{10}$, but the ion in copper (II) sulphate is $3d^9$, incomplete. One such oxidation state is enough.","feedback":"Misconception: Cu is not a transition element because its atom is $d^{10}$."},"ga":{"why":"Ga has d electrons, but they are complete in both the atom and the ion.","feedback":"Misconception: Any element with d electrons is a transition element."},"sc":{"why":"The ion has no d electrons, but the atom holds one electron in its 3d sublevel, which is incomplete.","feedback":"Misconception: An element whose only ion is $d^0$ is not a transition element."},"zn":{"why":"The 3d sublevel is complete in both the atom and the ion.","feedback":"Misconception: Every d-block element is a transition element."}},"explanation":"The book's definition: the d or f orbitals contain electrons but are not complete, in the atom or in one of its oxidation states. Sc: atom $3d^1$, incomplete. Cu: $\\ce{Cu^2+}$ is $3d^9$. Au: $\\ce{Au^3+}$ is $5d^8$. Zn and Ga: the d sublevel is $d^{10}$ in the atom and in the ion. So they are not transition elements."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"au":{"why":"الـ 5d في الذرة مكتمل، لكن في الـ +3 state بيبقى 5d⁸، مش مكتمل. ويكفي oxidation state واحدة زي دي.","feedback":"الفكرة الغلط: إن configuration الذرة لوحده هو اللي يهم."},"cu":{"why":"الذرة $3d^{10}$، لكن الـ ion اللي في الـ copper (II) sulphate بيبقى $3d^9$، يعني incomplete. وحالة واحدة زي دي كفاية.","feedback":"الفكرة الغلط: إن الـ Cu مش transition element عشان ذرته $d^{10}$."},"ga":{"why":"الـ Ga فيه d electrons، لكنها مكتملة في الذرة وفي الـ ion الاتنين.","feedback":"الفكرة الغلط: إن أي عنصر فيه d electrons يبقى transition element."},"sc":{"why":"الـ ion مفيهوش d electrons، لكن الذرة شايلة electron واحد في الـ 3d sublevel بتاعها، وده مش مكتمل.","feedback":"الفكرة الغلط: إن العنصر اللي الـ ion الوحيد بتاعه $d^0$ مش transition element."},"zn":{"why":"الـ 3d sublevel مكتمل في الذرة وفي الـ ion الاتنين.","feedback":"الفكرة الغلط: إن أي عنصر في الـ d-block يبقى transition element."}},"explanation":"تعريف الكتاب: الـ d أو الـ f orbitals فيها electrons لكن مش مكتملة، في الذرة أو في حالة من الـ oxidation states بتاعتها. الـ Sc: الذرة $3d^1$، incomplete. الـ Cu: الـ $\\ce{Cu^2+}$ هو $3d^9$. الـ Au: الـ $\\ce{Au^3+}$ هو $5d^8$. أما الـ Zn والـ Ga: الـ d sublevel فيهم $d^{10}$ في الذرة وفي الـ ion، يبقى مش transition elements."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":75,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.definition","section_title":"The transition element (definition)","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","The transition element (definition)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":10,"page_to":10,"section_key":"ch1.config.ex1","section_title":"Coinage metals","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Coinage metals"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":11,"page_to":11,"section_key":"ch1.config.ex2","section_title":"Zinc, cadmium and mercury","section_path":["Transition Elements","The Electronic Configurations and Oxidation states","Zinc, cadmium and mercury"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.multiple-oxidation-states-4","kind":"question","version":1,"ord":529,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"te.multiple-oxidation-states","concepts":[{"concept_id":"te.multiple-oxidation-states","role":"primary"},{"concept_id":"fe.reactions-nonmetals","role":"secondary"}],"title":"chem-s3-en.question-te.multiple-oxidation-states-4","payload":{"stem":"Consider the following statements about iron ($_{26}$Fe: [Ar] $4s^2\\,3d^6$): (I) Iron does not show the oxidation state +8, which would match the loss of all its 4s and 3d electrons. (II) Its oxidation states above +3 are not important. (III) In FeS, formed from iron and sulphur, iron is +3. Which statements are correct?","tags":["mixed","retrieval","correct-statements"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"(I) and (II) only","correct":true},{"id":"b","text":"(I) and (III) only","correct":false},{"id":"c","text":"(II) and (III) only","correct":false},{"id":"d","text":"(I), (II) and (III)","correct":false}],"book_ref":"Ch.1 'Chemical Properties' of iron, pp.20-21","difficulty":3,"concept_ids":["te.multiple-oxidation-states","fe.reactions-nonmetals"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Correct! (I): iron does not reach +8, the state that would match losing all its 4s and 3d electrons. (II): the book says iron's states above +3 are not important. (III) is wrong: in FeS sulphur is −2, so iron is +2."},"b":{"why":"(III) is wrong: in FeS, sulphur is −2 and there is one iron atom, so iron cannot be +3. And (II) was left out: the book calls iron's states above +3 not important.","feedback":"Misconception: Iron reaches +3 with sulphur."},"c":{"why":"Iron does not reach the state that matches all 8 electrons, so (I) is true and was left out. And (III) is wrong: in FeS, sulphur is −2, so iron is +2.","feedback":"Misconception: Iron reaches +8 like Mn reaches +7."},"d":{"why":"(III) is the wrong statement: in FeS, sulphur is −2 and there is one iron atom, so iron is +2, not +3.","feedback":"Misconception: Iron reaches +3 with sulphur."}},"explanation":"(I) is correct: iron differs from the elements before it; it does not reach +8. (II) is correct: the book says the states above +3 are not important. Iron's important states are +2 and +3. (III) is wrong: FeS is iron (II) sulphide. Sulphur is −2, so iron is +2."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح! (I): الـ iron مابيوصلش لـ +8، الـ state اللي كانت هتقابل إنه يفقد كل الـ 4s والـ 3d electrons. (II): الكتاب بيقول إن الـ states اللي فوق +3 في الـ iron مش مهمة. أما (III) فغلط: في الـ FeS الـ sulphur بيبقى −2، يبقى الـ iron بيبقى +2."},"b":{"why":"(III) غلط: في الـ FeS الـ sulphur بيبقى −2 وفيه ذرة iron واحدة، فمينفعش الـ iron يبقى +3. وكمان سبت (II): الكتاب بيقول إن الـ states اللي فوق +3 في الـ iron مش مهمة.","feedback":"الفكرة الغلط: إن الـ iron بيوصل لـ +3 مع الـ sulphur."},"c":{"why":"الـ iron مابيوصلش للـ state اللي بتقابل الـ 8 electrons كلهم، يبقى (I) صح وإنت سبتها. وكمان (III) غلط: في الـ FeS الـ sulphur بيبقى −2، يبقى الـ iron بيبقى +2.","feedback":"الفكرة الغلط: إن الـ iron بيوصل لـ +8 زي ما الـ Mn بيوصل لـ +7."},"d":{"why":"(III) هي الغلط: في الـ FeS، الـ sulphur بيبقى −2 وفيه ذرة iron واحدة، فالـ iron هنا +2 مش +3.","feedback":"الفكرة الغلط: إن الـ iron بيوصل لـ +3 مع الـ sulphur."}},"explanation":"(I) صح: الـ iron مختلف عن العناصر اللي قبله؛ مابيوصلش لـ +8. (II) صح: الكتاب بيقول إن الـ states اللي فوق +3 مش مهمة. والـ states المهمة للـ iron هي +2 و+3. (III) غلط: الـ FeS هو iron (II) sulphide. الـ sulphur بيبقى −2، يبقى الـ iron بيبقى +2."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":76,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.density-trend-4","kind":"question","version":1,"ord":530,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"te.density-trend","concepts":[{"concept_id":"te.density-trend","role":"primary"},{"concept_id":"te.atomic-radius","role":"secondary"},{"concept_id":"te.high-melting-points","role":"secondary"}],"title":"chem-s3-en.question-te.density-trend-4","payload":{"stem":"Use the table. Which statement is correct?","tags":["mixed","data","read-table"],"type":"mcq","bloom":"analyze","figure":{"root":"t","elements":{"t":{"type":"DataTable","props":{"rows":[["$\\ce{Mn}$",54.9,1.17,7.21,1247],["$\\ce{Fe}$",55.9,1.16,7.87,1538],["$\\ce{Co}$",58.9,1.16,8.7,1490],["$\\ce{Ni}$",58.7,1.15,8.9,1492]],"caption":"Book's table, p.12 (for illustration only)","headers":["Element","Atomic mass","Atomic radius","Density (g/cm³)","Melting point (°C)"]},"children":[]}}},"choices":[{"id":"a","text":"From Mn to Ni, the density increases while the atomic radius stays nearly constant.","correct":true},{"id":"b","text":"From Mn to Ni, the melting point increases with the atomic number.","correct":false},{"id":"c","text":"The element with the largest atomic radius has the highest density.","correct":false},{"id":"d","text":"Iron has both the highest melting point and the highest density of the four.","correct":false}],"book_ref":"Ch.1 table of general properties, p.12 (for illustration only)","difficulty":3,"concept_ids":["te.density-trend","te.atomic-radius","te.high-melting-points"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right: the density rises from 7.21 to 8.90 g/cm³ while the radius stays between 1.17 and 1.15."},"b":{"why":"The melting point does not rise every time: it falls from Fe (1538 °C) to Co (1490 °C).","feedback":"Misconception: Every property rises with the atomic number."},"c":{"why":"Mn has the largest radius here, but it has the lowest density.","feedback":"Misconception: A bigger atom means a denser metal."},"d":{"why":"Iron has the highest melting point (1538 °C), but not the highest density: nickel's 8.9 g/cm³ is higher than iron's 7.87.","feedback":"Misconception: Iron is the extreme in every property."}},"explanation":"Density: 7.21 → 7.87 → 8.70 → 8.90, so it increases. Radius: 1.17 → 1.16 → 1.16 → 1.15, nearly constant. The melting point does not rise steadily: iron (1538 °C) is the highest; cobalt (1490 °C) and nickel (1492 °C) are lower. Mn has the largest radius but the lowest density. The mass generally rises while the radius barely changes, so the density rises."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ density بتزيد من 7.21 لـ 8.90 g/cm³، والـ radius فاضل بين 1.17 و 1.15."},"b":{"why":"الـ melting point مش بيزيد في كل مرة: بيقل من الـ Fe (1538 °C) للـ Co (1490 °C).","feedback":"الفكرة الغلط: إن كل خاصية بتزيد مع الـ atomic number."},"c":{"why":"الـ Mn هو اللي الـ radius بتاعه الأكبر هنا، لكن الـ density بتاعته هي الأقل.","feedback":"الفكرة الغلط: إن الذرة الأكبر معناها metal الـ density بتاعه أعلى."},"d":{"why":"الـ iron عنده أعلى melting point (1538 °C)، لكن مش أعلى density: الـ 8.9 g/cm³ بتاعة الـ nickel أعلى من الـ 7.87 بتاعة الـ iron.","feedback":"الفكرة الغلط: إن الـ iron هو الحد الأقصى في كل خاصية."}},"explanation":"الـ density: من 7.21 لـ 7.87 لـ 8.70 لـ 8.90، يعني بتزيد. الـ radius: من 1.17 لـ 1.16 لـ 1.16 لـ 1.15، تقريبًا ثابت. الـ melting point مش بيزيد بانتظام: الـ iron (1538 °C) هو الأعلى، والـ cobalt (1490 °C) والـ nickel (1492 °C) أقل منه. الـ Mn الـ radius بتاعه الأكبر لكن الـ density بتاعته الأقل. الـ mass عمومًا بيزيد والـ radius يدوب بيتغيّر، فالـ density بتزيد."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":42,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.table","section_title":"Data table (atomic mass, radius, density, melting and boiling points)","section_path":["Transition Elements","The general properties of the first transition elements","Data table (atomic mass, radius, density, melting and boiling points)"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.magnetic-moment-from-config-7","kind":"question","version":1,"ord":531,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"te.magnetic-moment-from-config","concepts":[{"concept_id":"te.magnetic-moment-from-config","role":"primary"}],"title":"chem-s3-en.question-te.magnetic-moment-from-config-7","payload":{"stem":"Arrange the following ions in descending order according to their magnetic moment (largest first). ($_{22}$Ti, $_{24}$Cr, $_{25}$Mn, $_{29}$Cu)","tags":["mixed","retrieval","arrange"],"type":"order","bloom":"analyze","answer":["b","d","a","c"],"choices":[{"id":"a","text":"$\\ce{Ti^3+}$"},{"id":"b","text":"$\\ce{Mn^2+}$"},{"id":"c","text":"$\\ce{Cu+}$"},{"id":"d","text":"$\\ce{Cr^3+}$"}],"book_ref":"Ch.1 magnetic properties, p.14","difficulty":4,"concept_ids":["te.magnetic-moment-from-config"],"est_seconds":150},"layer":{"choices":{"a":{"why":"Ti has four electrons beyond [Ar]; after it loses three, one 3d electron stays, so 1 is unpaired."},"b":{"why":"Mn loses its two 4s electrons to form $\\ce{Mn^2+}$, leaving 3d⁵ with 5 unpaired electrons."},"c":{"why":"Cu is [Ar] $3d^{10}\\,4s^1$; after it loses the 4s electron, the ion is $3d^{10}$, with every 3d electron paired."},"d":{"why":"Cr is [Ar] $3d^5\\,4s^1$; it loses the 4s electron and two 3d electrons, leaving 3d³ with 3 unpaired."}},"explanation":"Mn²⁺: [Ar] $3d^5$, 5 unpaired. Cr³⁺: [Ar] $3d^3$, 3. Ti³⁺: [Ar] $3d^1$, 1. Cu⁺: [Ar] $3d^{10}$, 0, so it is diamagnetic. Descending order: Mn²⁺ > Cr³⁺ > Ti³⁺ > Cu⁺. Common slip: counting the atom's electrons instead of the ion's."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"الـ Ti عنده 4 electrons بعد الـ [Ar]؛ بعد ما يفقد 3 منهم بيفضل 3d electron واحد، يعني 1 unpaired."},"b":{"why":"الـ Mn بيفقد الاتنين 4s electrons بتوعه عشان يبقى $\\ce{Mn^2+}$، فبيفضل 3d⁵ وفيه 5 unpaired electrons."},"c":{"why":"الـ Cu هو [Ar] $3d^{10}\\,4s^1$؛ بعد ما يفقد الـ 4s electron، الـ ion بيبقى $3d^{10}$ وكل الـ 3d electrons بتوعه أزواج."},"d":{"why":"الـ Cr هو [Ar] $3d^5\\,4s^1$؛ بيفقد الـ 4s electron واتنين 3d electrons، فبيفضل 3d³ وفيه 3 unpaired."}},"explanation":"الـ Mn²⁺: [Ar] $3d^5$، يعني 5 unpaired. الـ Cr³⁺: [Ar] $3d^3$، يعني 3. الـ Ti³⁺: [Ar] $3d^1$، يعني 1. الـ Cu⁺: [Ar] $3d^{10}$، يعني 0، وعشان كده هو diamagnetic. يبقى الترتيب التنازلي: Mn²⁺ > Cr³⁺ > Ti³⁺ > Cu⁺. غلطة بتتكرر: إنك تعدّ electrons الذرة بدل electrons الـ ion."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":40,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":13,"page_to":14,"section_key":"ch1.properties.magnetic","section_title":"The Magnetic properties","section_path":["Transition Elements","The general properties of the first transition elements","The Magnetic properties"],"relation":"based_on"}]},{"id":"chem-s3-en.question-te.catalytic-activity-5","kind":"question","version":1,"ord":532,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"te.catalytic-activity","concepts":[{"concept_id":"te.catalytic-activity","role":"primary"},{"concept_id":"te.catalysis-examples","role":"secondary"}],"title":"chem-s3-en.question-te.catalytic-activity-5","payload":{"stem":"Give reasons: Finely divided iron is used as a catalyst in the preparation of ammonia by the Haber-Bosch method.","tags":["mixed","retrieval","give-reasons"],"type":"short","bloom":"understand","answer":"Key points: (1) Iron is a transition element with 4s and 3d electrons. (2) These electrons form bonds between the atoms of the iron surface and the reacting molecules ($\\ce{N2}$ and $\\ce{H2}$). (3) This increases the concentration of the reacting molecules on the surface and weakens the bonds in them. (4) So the activation energy decreases and the speed of the reaction increases: $\\ce{N2 + 3H2 ->[Fe] 2NH3}$.","book_ref":"Ch.1 'Catalytic activity', pp.14-15; exam form: give reasons","difficulty":3,"concept_ids":["te.catalytic-activity","te.catalysis-examples"],"est_seconds":90},"layer":{"explanation":"The book links catalytic activity to the 4s and 3d electrons. On the iron surface, they form bonds with $\\ce{N2}$ and $\\ce{H2}$ molecules. More molecules gather on the surface, and their bonds weaken. The activation energy falls, so ammonia forms faster. Finely divided iron has a larger surface. Most likely wrong answer: 'iron reacts with nitrogen and is used up'. A catalyst is not used up."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"الكتاب بيربط الـ catalytic activity بالـ 4s والـ 3d electrons. على سطح الـ iron، الـ electrons دي بتكوّن bonds مع الـ $\\ce{N2}$ والـ $\\ce{H2}$ molecules. فبتتجمع molecules أكتر على السطح، والـ bonds اللي فيها بتضعف. الـ activation energy بتقل، فالـ ammonia بتتكوّن أسرع. والـ finely divided iron سطحه أكبر. أكتر إجابة غلط متوقعة: 'iron reacts with nitrogen and is used up'. الـ catalyst مش بيتستهلك."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":41,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":14,"page_to":15,"section_key":"ch1.properties.catalytic","section_title":"Catalytic activity","section_path":["Transition Elements","The general properties of the first transition elements","Catalytic activity"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.midrex-reduction-5","kind":"question","version":1,"ord":533,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"fe.midrex-reduction","concepts":[{"concept_id":"fe.midrex-reduction","role":"primary"},{"concept_id":"fe.blast-furnace-reduction","role":"secondary"},{"concept_id":"fe.conversions","role":"secondary"}],"title":"chem-s3-en.question-fe.midrex-reduction-5","payload":{"stem":"Which choice compares the reduction of iron ore in the blast furnace and in the Midrex furnace correctly?","tags":["mixed","compare","choose"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"Blast furnace: CO from coke, higher than 700 °C. Midrex: a mixture of CO and $\\ce{H2}$ from natural gas.","correct":true},{"id":"b","text":"Blast furnace: $\\ce{H2}$ from coke. Midrex: CO only, from methane.","correct":false},{"id":"c","text":"Blast furnace: CO from coke, at 230–300 °C. Midrex: a mixture of CO and $\\ce{H2}$ from natural gas.","correct":false},{"id":"d","text":"Both furnaces use coke; the Midrex furnace adds natural gas only as a fuel.","correct":false,"misconception_id":"fe.midrex-reduction.mc2"}],"book_ref":"Ch.1 'Secondly: Reduction of Iron Ores' (a) and (b), p.18; exam form: compare","difficulty":3,"concept_ids":["fe.midrex-reduction","fe.blast-furnace-reduction","fe.conversions"],"est_seconds":75},"layer":{"choices":{"a":{"why":"Right: in the blast furnace, coke gives CO, which reduces the ore at higher than 700 °C; in the Midrex furnace, natural gas gives water gas, CO and $\\ce{H2}$."},"b":{"why":"Coke is carbon, so the reducing gas it gives is CO, not hydrogen. Methane (natural gas) brings the $\\ce{H2}$, in the Midrex furnace.","feedback":"Misconception: Coke gives hydrogen."},"c":{"why":"CO at 230–300 °C removes only a little oxygen and gives magnetic iron oxide ($\\ce{Fe3O4}$), not iron. The blast furnace works at higher than 700 °C.","feedback":"Misconception: CO at a low temperature gives iron."},"d":{"why":"In the book, each furnace gets its reducing gas from a different raw material: the Midrex furnace uses natural gas, not coke.","feedback":"Misconception: The Midrex furnace uses coke."}},"explanation":"Blast furnace: coke gives CO ($\\ce{C + O2 -> CO2}$, then $\\ce{CO2 + C -> 2CO}$). CO reduces $\\ce{Fe2O3}$ to iron at higher than 700 °C. Midrex: natural gas gives water gas, a mixture of CO and $\\ce{H2}$. Both gases reduce the ore. At 230–300 °C, CO would give only $\\ce{Fe3O4}$."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: في الـ blast furnace، الـ coke بيدّي CO، والـ CO بيختزل الـ ore عند أعلى من 700 °C؛ وفي الـ Midrex furnace، الـ natural gas بيدّي water gas، يعني CO و $\\ce{H2}$."},"b":{"why":"الـ coke ده carbon، والـ carbon بيدّي CO بس. الـ $\\ce{H2}$ جاي من الـ natural gas (الـ methane) في الـ Midrex furnace.","feedback":"الفكرة الغلط: إن الـ coke بيدّي hydrogen."},"c":{"why":"الـ CO عند 230–300 °C بيشيل يدوب شوية oxygen وبيدّي $\\ce{Fe3O4}$، مش iron.","feedback":"الفكرة الغلط: إن الـ CO في درجة حرارة واطية بيدّي iron."},"d":{"why":"في الكتاب، كل فرن بياخد الغاز المختزل بتاعه من مادة خام مختلفة: الـ Midrex furnace بياخده من الـ natural gas، مش من الـ coke.","feedback":"الفكرة الغلط: إن الـ Midrex furnace بيستخدم coke."}},"explanation":"الـ blast furnace: الـ coke بيدّي CO ($\\ce{C + O2 -> CO2}$، وبعدين $\\ce{CO2 + C -> 2CO}$). الـ CO بيختزل الـ $\\ce{Fe2O3}$ لـ iron عند درجة حرارة أعلى من 700 °C. الـ Midrex: الـ natural gas بيدّي water gas، اللي هو خليط من CO و $\\ce{H2}$. الغازين الاتنين بيختزلوا الـ ore. عند 230–300 °C، الـ CO هيدّي $\\ce{Fe3O4}$ وبس."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":65,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":18,"page_to":18,"section_key":"ch1.iron.reduction","section_title":"Reduction of Iron Ores","section_path":["Transition Elements","Iron","Extraction of Iron from its Ores","Reduction of Iron Ores"],"relation":"based_on"}]},{"id":"chem-s3-en.question-alloy.intermetallic-5","kind":"question","version":2,"ord":534,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"alloy.intermetallic","concepts":[{"concept_id":"alloy.intermetallic","role":"primary"},{"concept_id":"alloy.interstitial","role":"secondary"},{"concept_id":"alloy.substitutional","role":"secondary"}],"title":"chem-s3-en.question-alloy.intermetallic-5","payload":{"stem":"Classify the following alloys according to their type.","tags":["mixed","classify","new-case"],"type":"classify","bloom":"apply","answer":{"im":["ni3al","dural"],"int":["boron","steel"],"sub":["coni","fecr"]},"choices":[{"id":"coni","text":"An alloy of cobalt (radius 1.16) and nickel (radius 1.15), metals with the same crystal lattice and similar chemical properties"},{"id":"ni3al","text":"$\\ce{Ni3Al}$, a compound whose formula valency cannot explain"},{"id":"boron","text":"Iron with a little boron, whose atoms are much smaller than iron atoms (no fixed formula)","misconception_id":"alloy.interstitial.mc1"},{"id":"dural","text":"Duralumin (aluminum-copper)"},{"id":"fecr","text":"Ferrochrome in stainless steel","misconception_id":"alloy.substitutional.mc2"},{"id":"steel","text":"Steel","misconception_id":"alloy.interstitial.mc3"}],"book_ref":"Ch.1 'Types of alloys' 1-3, pp.19-20; atomic radius table, p.12","categories":[{"id":"int","label":"Interstitial alloy"},{"id":"sub","label":"Substitutional alloy"},{"id":"im","label":"Intermetallic alloy"}],"difficulty":3,"concept_ids":["alloy.intermetallic","alloy.substitutional","alloy.interstitial"],"est_seconds":120},"layer":{"choices":{"coni":{"why":"The two radii are nearly equal (1.16 and 1.15), so one atom can take the other's place; neither is small enough to fit in the spaces.","feedback":"Misconception: Any alloy of two metals is intermetallic."},"fecr":{"why":"Fe 1.16 and Cr 1.17 are nearly equal, so a Cr atom fits in an iron atom's place, not in a small space.","feedback":"Misconception: Fe-Cr is an interstitial alloy."},"boron":{"why":"Much smaller atoms cannot fill an iron atom's place; they fit in the spaces between the iron atoms.","feedback":"Misconception: Small atoms replace the host atoms."},"dural":{"why":"In the book's examples, the Al and Cu atoms of duralumin combine chemically into a compound; they do not only mix.","feedback":"Misconception: Duralumin is substitutional."},"ni3al":{"why":"A fixed formula that valency cannot explain shows that the elements are chemically combined, not just mixed.","feedback":"Misconception: Two metals always take each other's places."},"steel":{"why":"Carbon atoms are much smaller than iron atoms, so they fill gaps between the iron atoms instead of replacing them.","feedback":"Misconception: Steel and cementite are the same type."}},"explanation":"Interstitial: steel, and iron with boron, because much smaller atoms fit in the spaces. Substitutional: ferrochrome, and cobalt-nickel, because the atoms have nearly the same radius, lattice and properties. Intermetallic: duralumin and $\\ce{Ni3Al}$, because the elements combine chemically and the formula disobeys valency."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"coni":{"why":"الـ radius بتاع الاتنين تقريبًا واحد (1.16 و 1.15)، فذرة منهم تقدر تاخد مكان التانية، ومش هتدخل في فراغ صغير.","feedback":"الفكرة الغلط: إن أي alloy من اتنين metals يبقى intermetallic."},"fecr":{"why":"الـ Fe 1.16 والـ Cr 1.17، تقريبًا نفس الحجم، فذرة الـ Cr بتاخد مكان ذرة iron في الـ lattice.","feedback":"الفكرة الغلط: إن الـ Fe-Cr ده interstitial alloy."},"boron":{"why":"ذرات الـ boron أصغر بكتير من ذرات الـ iron، فمش بتاخد مكان ذرة iron؛ هي بتدخل في الفراغات.","feedback":"الفكرة الغلط: إن الذرات الصغيرة بتحل مكان الذرات الأساسية في الـ alloy."},"dural":{"why":"في أمثلة الكتاب، ذرات الـ Al والـ Cu في الـ duralumin بتتحد كيميائيًا، مش مجرد متخلطة.","feedback":"الفكرة الغلط: إن الـ duralumin نوعه substitutional."},"ni3al":{"why":"formula ثابتة والـ valency مش قادرة تفسّرها: ده معناه إن العناصر متحدة كيميائيًا، مش مجرد متخلطة.","feedback":"الفكرة الغلط: إن أي اتنين metals لازم ياخدوا أماكن بعض."},"steel":{"why":"ذرات الـ carbon أصغر بكتير من ذرات الـ iron، فمش بتحل مكان ذرات الـ iron؛ هي بتملا الفراغات.","feedback":"الفكرة الغلط: إن الـ steel والـ cementite من نفس النوع."}},"explanation":"الـ Interstitial: الـ steel، والـ iron مع الـ boron، لأن الذرات الأصغر بكتير بتدخل في الفراغات. الـ Substitutional: الـ ferrochrome، والـ cobalt مع الـ nickel، لأن الذرات ليها تقريبًا نفس الـ radius ونفس الـ lattice ونفس الخواص. الـ Intermetallic: الـ duralumin والـ $\\ce{Ni3Al}$، لأن العناصر بتتحد كيميائيًا والـ formula مش ماشية على الـ valency."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":32,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":19,"page_to":19,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":20,"page_to":20,"section_key":"ch1.alloys.types","section_title":"Types of alloys","section_path":["Transition Elements","Alloys","Types of alloys"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":12,"page_to":12,"section_key":"ch1.properties.radius","section_title":"Atomic radius","section_path":["Transition Elements","The general properties of the first transition elements","Atomic radius"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.passivity-5","kind":"question","version":1,"ord":535,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"fe.passivity","concepts":[{"concept_id":"fe.passivity","role":"primary"},{"concept_id":"fe.reaction-dilute-acids","role":"secondary"}],"title":"chem-s3-en.question-fe.passivity-5","payload":{"stem":"An iron nail is dipped in concentrated nitric acid, then washed. It is rubbed with sandpaper and put in dilute sulphuric acid. Which products form?","tags":["mixed","two-step","new-case"],"type":"mcq","bloom":"apply","choices":[{"id":"a","text":"$\\ce{FeSO4}$ and hydrogen gas","correct":true},{"id":"b","text":"No products: the nail stays passive","correct":false,"misconception_id":"fe.passivity.mc2"},{"id":"c","text":"$\\ce{Fe2(SO4)3}$ and hydrogen gas","correct":false},{"id":"d","text":"$\\ce{FeSO4}$, $\\ce{Fe2(SO4)3}$ and sulphur dioxide","correct":false}],"book_ref":"Ch.1 'Chemical Properties' 4 (with acids), p.21","difficulty":4,"concept_ids":["fe.passivity","fe.reaction-dilute-acids"],"est_seconds":90},"layer":{"choices":{"a":{"why":"Right: the sandpaper removed the passive oxide layer, so fresh iron reacts with the dilute acid: $\\ce{Fe + H2SO4 -> FeSO4 + H2}$."},"b":{"why":"The sandpaper rubbed the oxide layer off the nail, so the iron is no longer passive.","feedback":"Misconception: Passivity is permanent."},"c":{"why":"The layer was rubbed off, so fresh iron meets a dilute acid; the hydrogen produced keeps iron at +2 by reducing iron (III).","feedback":"Misconception: Nitric acid treatment makes iron give iron (III) salts later."},"d":{"why":"Those products need the hot concentrated acid, and the acid used here is dilute sulphuric acid.","feedback":"Misconception: Confusing the dilute acid with the hot concentrated acid."}},"explanation":"Concentrated nitric acid made the nail passive: a thin oxide layer formed. Abrasion with sandpaper removed the layer. Fresh iron then reacts with dilute sulphuric acid: $\\ce{Fe + H2SO4 -> FeSO4 + H2}$. The produced hydrogen keeps iron at +2."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ sandpaper شال طبقة الـ oxide اللي عملت الـ passivity، فالـ iron الجديد بيتفاعل مع الـ dilute acid: $\\ce{Fe + H2SO4 -> FeSO4 + H2}$."},"b":{"why":"الـ sandpaper شال طبقة الـ oxide من سطح المسمار، فالـ passivity مابقتش موجودة.","feedback":"الفكرة الغلط: إن الـ passivity دايمة."},"c":{"why":"الطبقة اتشالت بالحكّ. ومع dilute acid، الـ hydrogen اللي بيطلع بيخلّي الـ iron يفضل عند +2، مش iron (III).","feedback":"الفكرة الغلط: إن معاملة الـ iron بالـ nitric acid بتخليه يدّي iron (III) salts بعد كده."},"d":{"why":"النواتج دي محتاجة الـ hot concentrated acid، وهنا الـ acid المستخدم dilute sulphuric acid.","feedback":"الفكرة الغلط: الخلط بين الـ dilute acid والـ hot concentrated acid."}},"explanation":"الـ concentrated nitric acid خلّى المسمار passive: اتكوّنت عليه طبقة رقيقة من الـ oxide. والـ abrasion بالـ sandpaper شال الطبقة دي. بعد كده الـ iron الجديد بيتفاعل مع الـ dilute sulphuric acid: $\\ce{Fe + H2SO4 -> FeSO4 + H2}$. والـ hydrogen اللي بيطلع بيخلّي الـ iron يفضل عند +2."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":45,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.conversions-6","kind":"question","version":1,"ord":536,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"fe.conversions","concepts":[{"concept_id":"fe.conversions","role":"primary"},{"concept_id":"fe.oxide-fe2o3","role":"secondary"},{"concept_id":"fe.reactions-air-steam","role":"secondary"}],"title":"chem-s3-en.question-fe.conversions-6","payload":{"stem":"Study the diagram. Identify substances A, B, C and D, then write the balanced equations for steps (1) and (4).","tags":["mixed","diagram","conversion"],"type":"short","bloom":"analyze","answer":"A = $\\ce{Fe3O4}$, B = FeO, C = $\\ce{Fe2O3}$, D = $\\ce{Fe2(SO4)3}$ (with water). (1) $\\ce{3Fe + 4H2O ->[500\\,^{\\circ}C] Fe3O4 + 4H2}$. (4) $\\ce{Fe2O3 + 3H2SO4 ->[\\text{conc.},\\ \\Delta] Fe2(SO4)3 + 3H2O}$.","figure":{"root":"f","elements":{"f":{"type":"FlowDiagram","props":{"edges":[{"to":"a","from":"fe","label":"(1) water vapour, 500 °C"},{"to":"b","from":"a","label":"(2) CO, 400–700 °C"},{"to":"c","from":"b","label":"(3) hot air"},{"to":"d","from":"c","label":"(4) hot conc. $\\ce{H2SO4}$"}],"nodes":[{"id":"fe","label":"Fe"},{"id":"a","label":"A"},{"id":"b","label":"B"},{"id":"c","label":"C"},{"id":"d","label":"D"}],"layout":"horizontal","caption":"Iron conversions with conditions"},"children":[]}}},"book_ref":"Ch.1 Evaluation Q6 (conversion diagrams), p.26; reactions pp.18, 21-24","difficulty":5,"concept_ids":["fe.conversions","fe.reactions-air-steam","fe.oxide-fe2o3"],"est_seconds":240},"layer":{"explanation":"(1) Red hot iron and water vapour give magnetic iron oxide and hydrogen. (2) CO at 400–700 °C reduces it to FeO. (3) FeO is easily oxidized in hot air to $\\ce{Fe2O3}$. (4) $\\ce{Fe2O3}$ and the hot concentrated acid give iron (III) sulphate and water. Most likely slip: two salts for D. Of the iron oxides, only $\\ce{Fe3O4}$ gives two salts. $\\ce{Fe2O3}$ holds iron only at +3, so D is iron (III) sulphate alone."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"explanation":"(1) الـ iron المسخّن لدرجة الاحمرار مع بخار المية بيدوا magnetic iron oxide والـ hydrogen. (2) الـ CO عند 400–700 °C بيعمله reduction لحد FeO. (3) الـ FeO بيحصله oxidation بسهولة في الهوا السخن ويبقى $\\ce{Fe2O3}$. (4) الـ $\\ce{Fe2O3}$ مع الـ acid الـ concentrated السخن بيدوا iron (III) sulphate ومية. أشهر غلطة: إنك تكتب اتنين salts في D. من بين الـ iron oxides، الـ $\\ce{Fe3O4}$ لوحده هو اللي بيدي اتنين salts. والـ $\\ce{Fe2O3}$ فيه iron عند +3 تحديدًا، يعني D هو iron (III) sulphate لوحده."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":28,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":21,"page_to":21,"section_key":"ch1.iron.chemical","section_title":"Chemical properties of iron","section_path":["Transition Elements","Iron","Properties of Iron","Chemical properties of iron"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.question-fe.oxide-fe3o4-6","kind":"question","version":1,"ord":537,"group_id":"chem-s3-en.ch1.practice.mixed","primary_concept_id":"fe.oxide-fe3o4","concepts":[{"concept_id":"fe.oxide-fe3o4","role":"primary"},{"concept_id":"fe.oxide-fe2o3","role":"secondary"},{"concept_id":"fe.oxide-feo","role":"secondary"}],"title":"chem-s3-en.question-fe.oxide-fe3o4-6","payload":{"stem":"Three iron oxides X, Y and Z are tested. X, a black powder, gives only iron (II) sulphate and water with dilute $\\ce{H2SO4}$. Y is strongly attracted by a magnet and gives two iron salts with hot concentrated $\\ce{H2SO4}$. Z, a red solid, gives only iron (III) sulphate and water with hot concentrated $\\ce{H2SO4}$. Identify X, Y and Z.","tags":["mixed","data","identify"],"type":"mcq","bloom":"understand","choices":[{"id":"a","text":"X = FeO, Y = $\\ce{Fe3O4}$, Z = $\\ce{Fe2O3}$","correct":true},{"id":"b","text":"X = $\\ce{Fe2O3}$, Y = $\\ce{Fe3O4}$, Z = FeO","correct":false},{"id":"c","text":"X = FeO, Y = $\\ce{Fe2O3}$, Z = $\\ce{Fe3O4}$","correct":false},{"id":"d","text":"X = $\\ce{Fe3O4}$, Y = FeO, Z = $\\ce{Fe2O3}$","correct":false}],"book_ref":"Ch.1 'IRON Oxides' 1-3, pp.22-24","difficulty":3,"concept_ids":["fe.oxide-fe3o4","fe.oxide-feo","fe.oxide-fe2o3"],"est_seconds":120},"layer":{"choices":{"a":{"why":"Right: X gives only an iron (II) salt, so it is FeO; Y is the strong magnet that gives two salts, $\\ce{Fe3O4}$; Z is red and gives only an iron (III) salt, $\\ce{Fe2O3}$."},"b":{"why":"X gives an iron (II) salt, so iron is +2 in X; that fits FeO, not the +3 oxide.","feedback":"Misconception: Mixing up the iron (II) and iron (III) oxides."},"c":{"why":"Two Fe atoms in a formula do not mean two oxidation states: $\\ce{Fe2O3}$ has iron at +3 only. The strong magnet that gives two salts is the mixed oxide, magnetite ($\\ce{Fe3O4}$).","feedback":"Misconception: $\\ce{Fe2O3}$ gives two salts because it has two Fe atoms."},"d":{"why":"FeO and $\\ce{Fe3O4}$ are both black. The magnet and the number of salts separate them: only $\\ce{Fe3O4}$ is a strong magnet and gives two salts.","feedback":"Misconception: Every black iron oxide is the magnetic one."}},"explanation":"X gives only an iron (II) salt, so iron is +2: X is FeO, the black powder. Y is a strong magnet and gives two salts: the mixed oxide $\\ce{Fe3O4}$. Z is red and gives only an iron (III) salt: $\\ce{Fe2O3}$. Use the oxidation state of iron in each salt to decide."},"layer_lang":"en","layer_fallback":false,"reveal_layer":{"choices":{"a":{"why":"صح: الـ X بيدّي iron (II) salt لوحده، يبقى FeO؛ والـ Y هو الـ strong magnet اللي بيدّي ملحين، يبقى $\\ce{Fe3O4}$؛ والـ Z أحمر وبيدّي iron (III) salt لوحده، يبقى $\\ce{Fe2O3}$."},"b":{"why":"الـ oxide اللي بيدّي iron (II) salt لوحده فيه iron عند +2، والـ oxide اللي بيدّي iron (III) salt لوحده فيه iron عند +3؛ الـ oxidation state في كل formula بيحدد ده.","feedback":"الفكرة الغلط: إنك تلخبط بين الـ iron (II) oxide والـ iron (III) oxide."},"c":{"why":"وجود 2 Fe atoms في الـ formula مش معناه 2 oxidation states؛ الـ $\\ce{Fe2O3}$ فيه iron عند +3 بس، والـ strong magnet هو الـ $\\ce{Fe3O4}$.","feedback":"الفكرة الغلط: إن الـ $\\ce{Fe2O3}$ بيدّي ملحين عشان فيه 2 Fe atoms."},"d":{"why":"الـ FeO والـ $\\ce{Fe3O4}$ الاتنين لونهم أسود، فاللون لوحده مش كفاية؛ الـ magnet وعدد الأملاح هما اللي بيفرّقوا بينهم.","feedback":"الفكرة الغلط: إن أي iron oxide أسود هو الـ magnetic."}},"explanation":"الـ X بيدّي iron (II) salt لوحده، يعني الـ iron +2: الـ X هو FeO، المسحوق الأسود. الـ Y هو strong magnet وبيدّي ملحين: يبقى الـ mixed oxide $\\ce{Fe3O4}$. الـ Z أحمر وبيدّي iron (III) salt لوحده: يبقى $\\ce{Fe2O3}$. استخدم الـ oxidation state بتاع الـ iron في كل ملح عشان تحدد."},"reveal_lang":"ar-EG","images":{},"files":[],"countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":29,"book_refs":[{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":22,"page_to":22,"section_key":"ch1.iron.oxides.feo","section_title":"Iron (II) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (II) oxide"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":24,"page_to":24,"section_key":"ch1.iron.oxides.fe3o4","section_title":"The black oxide (magnetic iron oxide)","section_path":["Transition Elements","Iron","Iron Oxides","The black oxide (magnetic iron oxide)"],"relation":"based_on"},{"source_sha":"05c581197e3e33c6e0c0d48a885b36905065a15b10fd3ec2b05e470ea4c06e9d","source_title":"Chemistry, General Secondary Certificate, Part 1 (English, 2026-2027)","page_from":23,"page_to":23,"section_key":"ch1.iron.oxides.fe2o3","section_title":"Iron (III) oxide","section_path":["Transition Elements","Iron","Iron Oxides","Iron (III) oxide"],"relation":"based_on"}]},{"id":"chem-s3-en.video-short-phys.electric-charges","kind":"short","version":1,"ord":1,"content_lang":"ar-EG","primary_concept_id":"phys.electric-charges","concepts":[{"concept_id":"phys.electric-charges","role":"primary"}],"title":"Electric charges attract and repel","payload":{"title":"Electric charges attract and repel","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): YK.atomDisc-style nucleus (pink, '+' charge, r 90) at (540, 1080) with three small cyan '−' electron dots jittering around it (YK.rng seed, no circular orbit paths) + hook already on screen at t=0 in the headline band (x 108, Cairo 1000 ~110): 'What holds electrons in?'. Signals: the dots flash on cue l1 'electrons', the nucleus glows on 'nucleus', 'holds' pulses gold on cue 'ماسكهم'. Label 'nucleus' (48, textDim) right of the nucleus on cue l1 'nucleus' (spoken term on screen, L5); 'electrons' is in the hook text.","tts_text":"الـ electrons حوالين الـ nucleus… إيه اللي ماسكهم ومخليهم ميطيروش؟","screen_text":"What holds electrons in?"},{"id":"l2","visual":"Hook text exits on cue l2 'charge'; headline 'Two kinds of charge' (Cairo 1000, 80) enters in the band on the same cue. Atom slides down and dims to 35% (G17). Two big charge spheres (r 120, YK.atomDisc-style, symbol drawn as '+' / '−') enter from the left at y 950: pink '+' on cue l2 'positive' with label 'positive (+)' (48) under it, cyan '−' on cue 'negative' with label 'negative (−)' (48).","tts_text":"الـ charge نوعين بس: positive و negative، مفيش غيرهم.","screen_text":"Two kinds of charge: positive (+), negative (−)"},{"id":"l3","visual":"Two pink '+' spheres ONLY (no '−' pair: the l7 check must stay a new case) at x 360 / 720, y 1000; on cue l3 'like' both pulse; on cue 'repel' they slide apart to x 220 / 860 with an outward coral YK.arrow pair; label 'Like charges repel' (56) under them on the same cue.","tts_text":"الـ like charges بتعمل repel، يعني بتزق بعض بعيد.","screen_text":"Like charges repel"},{"id":"l4","visual":"Rows clear; a pink '+' (x 260) and a cyan '−' (x 820) at y 1100. On cue l4 'unlike' both pulse; on cue 'attract' inward YK.arrow pair (mint) and they start drifting together; label 'Unlike charges attract' (56).","tts_text":"والـ unlike charges بتعمل attract، بتشد بعض.","screen_text":"Unlike charges attract"},{"id":"l5","visual":"Same pair keeps approaching (x 260→440 / 820→640, YK.prog over the line); the mint arrows thicken; a simple horizontal strength bar (YK.roundRect, 520×36, x 280, y 1380, mint fill 30%→90% from cue 'attraction' to cue 'أقوى') with label 'attraction' (48) on its left end. Headline 'Closer → stronger attraction' (72) in the band on cue 'attraction'. No YK.momentMeter (it is the unpaired-electron gauge).","tts_text":"وكل ما يقرّبوا من بعض، الـ attraction بيبقى أقوى.","screen_text":"Closer → stronger attraction"},{"id":"l6","visual":"Aha (hold ≥ 1.5 s): camera returns to the l1 atom, now at 100%. On cue l6 'nucleus' the nucleus '+' glows pink; on cue 'electrons' the '−' dots glow cyan and short mint arrows point from each electron to the nucleus; label 'Nucleus (+) pulls electrons (−)' (56) under the atom. Answers the l1 hook. (Ch.1 p.12 uses this pull: nuclear attraction to electrons, atomic radius.)","tts_text":"عشان كده الـ nucleus الـ positive بيشد الـ electrons الـ negative، وده اللي ماسكهم.","screen_text":"Nucleus (+) pulls electrons (−)"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8): two cyan '−' spheres at x 400 / 680, y 1050, no arrows. Question 'Two electrons, side by side: attract or repel?' (Cairo 900, 72, ≤ 2 lines) in the headline band on cue l7 'electrons'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the ≥ 1 s silence (<long pause>; narrator widens the l7→l8 gap to ≥ 1 s if trimmed).","tts_text":"طب اتنين electrons جنب بعض؟ هيعملوا attract ولا repel؟ فكّروا. <long pause>","screen_text":"Two electrons, side by side: attract or repel?"},{"id":"l8","visual":"Answer: on cue l8 'repel' the two spheres slide apart with coral outward arrows + YK.rightMark; label 'Repel: both negative' (56) on cue 'negative'. (Same repulsion the chapter uses between 3d electrons, Ch.1 p.12.)","tts_text":"repel، لأن الاتنين negative، فبيزقّوا بعض.","screen_text":"Repel: both negative"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Electric charges attract and repel', line:'Like charges repel; unlike charges attract.'}) from cue l9 start, held through the line + tail (≥ 2.5 s). Signals: 'repel' pulses coral on cue 'repel', 'attract' mint on cue 'attract'. Loop (S5): last 0.8 s the card exits and the l1 atom (nucleus + jittering electrons) is alone at (540, 1080).","tts_text":"like charges بتعمل repel، و unlike attract لبعض.","screen_text":"Like charges repel; unlike charges attract."}],"logline":"Two kinds of charge: like charges repel, unlike charges attract, more strongly when closer; that pull is what keeps the negative electrons around the positive 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electrons حوالين الـ nucleus إيه اللي\nماسكهم ومخليهم ميطيروش\nالـ charge نوعين بس positive و negative\nمفيش غيرهم\nالـ like charges بتعمل repel يعني بتزق بعض\nبعيد\nوالـ unlike charges بتعمل attract بتشد بعض\nوكل ما يقرّبوا من بعض الـ attraction بيبقى\nأقوى\nعشان كده الـ nucleus الـ positive بيشد الـ\nelectrons الـ negative وده اللي ماسكهم\nطب اتنين electrons جنب بعض هيعملوا attract\nولا repel فكّروا\nrepel لأن الاتنين negative فبيزقّوا بعض\nlike charges بتعمل repel و unlike attract\nلبعض","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":5},{"id":"chem-s3-en.video-short-sci.matter-particles","kind":"short","version":1,"ord":3,"content_lang":"ar-EG","primary_concept_id":"sci.matter-particles","concepts":[{"concept_id":"sci.matter-particles","role":"primary"}],"title":"Matter is made of atoms and molecules","payload":{"title":"Matter is made of atoms and molecules","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): a grey iron bar (rounded rect 700×220, metallic gradient, slow specular sweep) centred at y 1050 + hook already on screen at t=0 (headline band, Cairo 1000 ~110): 'Solid iron. Any empty space?'. Signal: 'empty space' pulses gold on cue l1 'فراغات'.","tts_text":"حتة الـ iron دي شكلها مصمتة خالص… فيها فراغات ولا لأ؟","screen_text":"Solid iron. Any empty space?"},{"id":"l2","visual":"YK.zoomThrough(ctx, t, {from: drawIronBar, to: drawLattice, p: YK.ease.inOut(YK.prog(t, YK.cue('l2','particles'), +1.0)), focus:{x:540, y:1050}, badge:'×10^8'}) — keep calling with p = 1 for ~1.5 s so the badge stays, then badgeOut. drawLattice = YK.lattice(ctx, 160, 760, 760, 620, {rows:5, cols:6, pack:'hex', color:'#8FA3BF'}). Hook exits; headline 'Matter = tiny particles' (72) on cue 'particles'.","tts_text":"أي matter معمولة من particles صغيرة جدًا.","screen_text":"Matter = tiny particles"},{"id":"l3","visual":"On cue l3 'atom' one lattice ball is outlined gold and pops forward as YK.atomDisc(ctx, 540, 900, 110, {el:'Fe'}); label 'Atom: iron (Fe)' (56) beside it, 'iron' gold on cue 'iron' (spoken term shown, L5). The rest of the lattice stays at 60%.","tts_text":"الـ particle ممكن تبقى atom لوحده، زي الـ iron كده.","screen_text":"Atom: iron (Fe)"},{"id":"l4","visual":"Lattice slides left and dims to 35%; on cue l4 'molecule' YK.molecule(ctx, 540, 1000, {formula:'H2O'}) enters from the left, then a little cluster of 6 H₂O molecules forms around it on cue 'المية'. Label 'Molecule: H₂O' (YK.label, 56).","tts_text":"أو molecule، atoms لازقة في بعض، زي H two O، المية.","screen_text":"Molecule: H₂O"},{"id":"l5","visual":"Back to the iron lattice at 100% (y 1050). On cue l5 'بتتحرك' every ball starts a small deterministic vibration (±8 px, YK.rng phase per ball, sin(t)) — they stay in place; short motion ticks around 3 balls. Label 'Always moving' (56) on the same cue; on cue 'iron' the vibration amplitude pulses.","tts_text":"والـ particles دي بتتحرك على طول، حتى في الـ iron الصلب.","screen_text":"Always moving"},{"id":"l6","visual":"On cue l6 'spaces' the gaps between lattice balls glow (mint fill in the interstices, YK.pulse), label 'Spaces between particles' (56) under the lattice.","tts_text":"وبين كل particle والتانية spaces فاضية.","screen_text":"Spaces between particles"},{"id":"l7","visual":"Aha (hold ≥ 1.5 s): camera pulls back halfway: the bar outline is drawn faint around the lattice (macro and atomic in one frame) with the gaps still glowing and balls vibrating; label 'Solid iron = moving atoms + spaces' (56). Answers the l1 hook. (Chapter 1 later fits small atoms into these spaces: interstitial alloys, Ch.1 alloys section.)","tts_text":"يعني الـ iron ده: atoms بتهتز، وبينها فراغات حقيقية.","screen_text":"Solid iron = moving atoms + spaces"},{"id":"l8","style":"curious","visual":"Self-check on a new case (R8): a static copper-coloured wire (horizontal, y 1000, #B87333) on a grey line. Question 'A copper wire: are its particles moving?' (Cairo 900, 72, ≤ 2 lines) in the headline band on cue l8 'copper'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l8','فكّروا'), dur: YK.cue('l9') - that start, question:'', answer:''}) through the ≥ 1 s silence.","tts_text":"طب سلك copper واقف… الـ particles بتاعته بتتحرك؟ فكّروا. <long pause>","screen_text":"A copper wire: are its particles moving?"},{"id":"l9","visual":"Answer: on cue l9 'أيوه' a magnifier circle (r 220) opens on the wire showing a small copper lattice vibrating + YK.rightMark; label 'Yes: they vibrate in place' (56) on cue 'vibrate'.","tts_text":"أيوه، بيعملوا vibrate مكانهم، حتى لو السلك واقف.","screen_text":"Yes: they vibrate in place"},{"id":"l10","visual":"Voiced lock-in (S3): YK.takeaway({title:'Matter is made of atoms and molecules', line:'Matter: moving particles with spaces between.'}) from cue l10 start, held through the line + tail (≥ 2.5 s). Signals: 'moving' pulses on cue 'بتتحرك', 'spaces' on cue 'مسافات'. Loop (S5): last 0.8 s returns to the solid iron bar of frame 0.","tts_text":"أي matter: particles بتتحرك، وبينها مسافات.","screen_text":"Matter: moving particles with spaces between."}],"logline":"A solid iron bar looks continuous, but zoom in: it is tiny particles (atoms, or molecules like H₂O) that never stop moving, with spaces between 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Signals: '26' flashes on cue l1 'الستة'; 'Fe' pulses on cue 'iron'. Book notation as in Ch.1 p.8 table (₂₆Fe).","tts_text":"الستة وعشرين اللي جنب الـ iron دي… بتعدّ إيه؟","screen_text":"₂₆Fe: what does 26 count?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Structure of the atom', {kind:'prereq', align:'center'}) at line start (≤ 2 s); hook exits. The formula shrinks to the top-left (x 160, y 560, 80). YK.atom(ctx, 540, 1100, {shells:[2,8,14,2], nucleusLabel:'', size:380, rotate:0}) builds; YK.atom draws no nucleons, so the page draws a nucleus cluster of 14 representative discs (r 20, 7 pink protons + 7 grey neutrons, YK.rng-seeded packing inside r 85, no text): it appears on cue l2 'nucleus'; labels 'protons' (48, pink) and 'neutrons' (48, grey) with leader lines on their cues; the outer electrons glow cyan on cue 'electrons' with label 'electrons' (48).","tts_text":"جوه الـ nucleus فيه protons و neutrons، والـ electrons برّه.","screen_text":"protons + neutrons | electrons"},{"id":"l3","visual":"On cue l3 'atomic' the '26' of the corner formula slides (YK.tween 0.4 s, outBack) to a tag 'Atomic number' (56, gold) beside the nucleus; on cue 'protons' the pink discs pulse and a counter YK.counter 0→26 runs next to them. Headline 'Atomic number = number of protons' (64, 2 lines) in the band on cue 'atomic'.","tts_text":"الـ atomic number، عدد الـ protons جوه.","screen_text":"Atomic number = number of protons"},{"id":"l4","visual":"On cue l4 'neutral' a small balance glyph (YK.balance, p from cue) appears under the atom: left pan '26 protons (+)', right pan '26 electrons (−)', level. On cue 'electrons' the 26 cyan electrons pulse shell by shell. Label 'Neutral atom: electrons = protons' (56).","tts_text":"وفي الـ neutral atom، الـ electrons بعدد الـ protons.","screen_text":"Neutral atom: electrons = protons"},{"id":"l5","visual":"Balance exits; on cue l5 'mass' the nucleus zooms (YK.camera 0.8 s) and protons + neutrons both glow; headline YK.label 'Mass number = protons + neutrons' (Cairo 800, 64, 2 lines; not mono) with 'protons' pink and 'neutrons' grey on their cues. One new term in this line.","tts_text":"أما الـ mass number، فهو الـ protons والـ neutrons مع بعض.","screen_text":"Mass number = protons + neutrons"},{"id":"l6","visual":"Aha (hold ≥ 1.5 s): camera back to the full atom; big '_{26}Fe' returns to centre-top (y 640, 140). On cue l6 'ستة' (first number word) the nucleus glows pink with tag '26 protons'; on cue 'electrons' all electrons glow cyan with tag '26 electrons' (56). Answers the l1 hook: 26 counts protons (and the electrons Chapter 1 arranges).","tts_text":"الـ iron فيه ستة وعشرين proton، والـ electrons زيهم.","screen_text":"₂₆Fe: 26 protons, 26 electrons"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8): YK.formula '^{55}_{25}Mn' (mono 180) at y 1000, labels 'mass number' (48) pointing to 55 and 'atomic number' (48) pointing to 25. Question '⁵⁵₂₅Mn: how many neutrons?' (Cairo 900, 72) in the headline band on cue l7 'manganese'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the ≥ 1 s silence.","tts_text":"جرّبوا الـ manganese: خمسة وعشرين، وخمسة وخمسين. فيه كام neutron جوه؟ فكّروا. <long pause>","screen_text":"⁵⁵₂₅Mn: how many neutrons?"},{"id":"l8","visual":"Answer: on cue l8 'تلاتين' the sum builds as YK.formula '55 − 25 = !{30}' (mono 96) under the symbol, '30 neutrons' (56) + YK.rightMark on cue 'ناقص'.","tts_text":"تلاتين neutron: خمسة وخمسين ناقص خمسة وعشرين.","screen_text":"55 − 25 = 30 neutrons"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Atomic number and mass number', line:'Atomic number = protons; mass number = protons + neutrons.', formula:'^{55}_{25}Mn'}) from cue l9 start, held through the line + tail (≥ 2.5 s). Signals: 'Atomic number' gold on cue l9 'atomic', 'mass number' gold on cue 'mass'. Loop (S5): last 0.8 s returns to the big '_{26}Fe' of frame 0 with '26' pulsing.","tts_text":"الـ atomic number عدد الـ protons، والـ mass number protons و neutrons مع بعض.","screen_text":"Atomic number = protons; mass number = protons + neutrons."}],"logline":"In ₂₆Fe the 26 is the atomic number: 26 protons, and in a neutral atom 26 electrons to arrange; the mass number adds the 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levels","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): a pink nucleus 'Fe' (r 70) at (540, 1100) with 26 cyan electron dots swarming loosely around it (deterministic noise, YK.rng seed, no rings yet) + hook already on screen at t=0 (headline band, Cairo 1000 ~100, 2 lines): '26 electrons.' / 'Where do they sit?'. Signals: dots flash on cue l1 'electron', 'Where' pulses gold on cue 'فين'.","tts_text":"الـ iron فيه ستة وعشرين electron… قاعدين فين بالظبط؟","screen_text":"26 electrons. Where do they sit?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Atomic number and mass number', {kind:'prereq', align:'center'}) at line start (≤ 2 s); hook exits. On cue l2 'main' the swarm snaps into YK.atom(ctx, 540, 1100, {shells:[2,8,14,2], nucleusLabel:'Fe', size:400, reveal: prog from cue, rotate:t}) rings drawing outward; ring tags 'K (n = 1)', 'L (n = 2)', 'M (n = 3)', 'N (n = 4)' (48, right side, book/lesson letters) on cue 'التاني'. Headline 'Main energy levels' (72) on cue 'main'. No 4s/3d sublevel detail.","tts_text":"بيتوزّعوا على main energy levels، واحد جوه التاني.","screen_text":"Main energy levels"},{"id":"l3","visual":"Atom dims to 35% and moves down (y 1350). On cue l3 'أربع' the four ring tags K, L, M, N flash together (scope: only these four levels); on cue l3 'two' YK.formula 'Max electrons = 2n^2' (mono 96, '2n²' gold) centred at y 760 with a scope tag 'n = 1 to 4 (K to N)' (48) under it; on cue 'بالكتير' a capacity bar outline appears next to each of the four ring tags.","tts_text":"أول أربع levels، كل level بياخد بالكتير two n squared electrons، مش أكتر.","screen_text":"Levels n = 1 to 4: max electrons = 2n²"},{"id":"l4","visual":"Three rows (≤ 3 items) build top → bottom under the formula, each on its number cue: 'n = 1: 2 × 1² = 2', 'n = 2: 2 × 2² = 8', 'n = 3: 2 × 3² = 18' (YK.formula mono 64), the matching ring in the dimmed atom flashing gold with each row.","tts_text":"الأول اتنين، التاني تمانية، التالت تمنتاشر.","screen_text":"n = 1: 2 · n = 2: 8 · n = 3: 18"},{"id":"l5","visual":"Aha (hold ≥ 1.5 s): rows exit; atom back to 100% at (540, 1100). Rings light up inner → outer on each spoken number with counts '2', '8', '14', '2' (56) at their tags; the third ring shows '14 / 18' (it still has room: Chapter 1's 3d electrons fill here, Ch.1 p.8). Headline YK.formula '_{26}Fe: 2, 8, 14, 2' (mono 80). Answers the l1 hook.","tts_text":"والـ iron: اتنين، تمانية، أربعتاشر، واتنين برّه.","screen_text":"₂₆Fe: 2, 8, 14, 2"},{"id":"l6","visual":"Fe atom slides out; on cue l6 'calcium' YK.atom(ctx, 540, 1100, {shells:[2,8,8,2], nucleusLabel:'Ca', size:400}) rises with YK.formula '_{20}Ca: 2, 8, 8, 2' (mono 72) in the headline band. On cue 'آخر' the outer ring (n = 4) is highlighted (highlightShell:3, gold) and its 2 electrons glow; label 'Outer level: valence electrons' (56) on cue 'valence'. No valence label on iron anywhere (Fe also uses 3d electrons, book p.8-9).","tts_text":"خد الـ calcium: الاتنين اللي في آخر level هما الـ valence electrons، اللي بتتفاعل.","screen_text":"₂₀Ca: 2, 8, 8, 2 → outer level: valence electrons"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8): YK.atom(ctx, 540, 1100, {shells:[2,8,1], reveal:0.3 (nucleus + empty rings only), nucleusLabel:'Na', size 380}) — rings empty, 11 electrons hovering. Question '₁₁Na: how many valence electrons?' (Cairo 900, 72) in the headline band on cue l7 'sodium'. YK.checkPause(ctx, 540, 1580, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the ≥ 1 s silence.","tts_text":"طب الـ sodium فيه حداشر electron. كام valence electron؟ فكّروا. <long pause>","screen_text":"₁₁Na: how many valence electrons?"},{"id":"l8","visual":"Answer: on cue l8 'valence' (first word) '1 valence electron' (56, gold) + YK.rightMark; then electrons drop into rings 2 → 8 → 1 on the three spoken numbers; the lone outer electron glows gold on cue 'برّه'; YK.formula '_{11}Na: 2, 8, 1' (mono 72) builds with the numbers.","tts_text":"valence electron واحد بس: اتنين، تمانية، وواحد برّه.","screen_text":"₁₁Na: 2, 8, 1 → 1 valence electron"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Main energy levels', line:'Levels n = 1 to 4 (K to N) hold up to 2n² electrons.', formula:'2n^2'}) from cue l9 start, held through the line + tail (≥ 2.5 s). Signals: 'n = 1 to 4' pulses gold on cue 'أربع', the formula pulses gold on cue 'two'. Loop (S5): last 0.8 s the card exits to the Fe atom (2, 8, 14, 2 rings, rotating) at (540, 1100) as in frame 0, now ordered.","tts_text":"أول أربع levels: two n squared electrons بالكتير.","screen_text":"Levels n = 1 to 4 (K to N) hold up to 2n² electrons."}],"logline":"Iron's 26 electrons sit in main energy levels around the nucleus; the first four levels (K to N) hold at most 2n² electrons, so iron is 2, 8, 14, 2, and in calcium (2, 8, 8, 2) the outer-level electrons are the valence 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symbols","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): YK.elementCard(ctx, 540, 1080, {sym:'Fe', nameEn:'Iron', config:'', w:420}) slowly tilting/breathing + hook already on screen at t=0 (headline band, Cairo 1000 ~110): 'Iron = Fe. Why Fe?'. Signals: card glows (hl) on cue l1 'iron'; the 'Fe' symbol pulses gold on cue 'منين'.","tts_text":"رمز الـ iron مش جاي من كلمة iron خالص… أومال جاي منين؟","screen_text":"Iron = Fe. Why Fe?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Matter is made of atoms and molecules', {kind:'prereq', align:'center'}) at line start (≤ 2 s). Card shrinks to the top-right; on cue l2 'element' a sample cube (YK.lattice rows 4, cols 5, all balls the same grey) fills the stage; on cue 'نوع' every ball flashes the same colour at once. Label 'Element: one kind of atom' (56).","tts_text":"الـ element مادة نقية، كل الـ atoms فيها نوع واحد.","screen_text":"Element: one kind of atom"},{"id":"l3","visual":"Lattice exits; three YK.elementCard tiles in a row (w 280 each, x 230 / 540 / 850, y 1050, config:'', nameEn:'' — at w < 380 the card's own name text drops under 40 px, so names are separate labels in l4): O, Zn, Fe enter left → right on cue l3 'symbol'; on cue 'capital' the first letter of each symbol is boxed gold, the 'n' of Zn boxed mint. Headline 'Symbol: one capital, or capital + small' (64, 2 lines; lesson wording).","tts_text":"وكل element ليه symbol، حرف أو اتنين، أولهم capital دايمًا.","screen_text":"Symbol: one capital, or capital + small"},{"id":"l4","visual":"O and Zn cards glow in turn on cues l4 'oxygen' and 'zinc'; under each, its English name appears on its cue (YK.text 48): 'Oxygen' (O gold), 'Zinc' (Z, n gold). Fe card stays dimmed 50% with no name yet.","tts_text":"ساعات الـ symbol من اسمه الإنجليزي، زي الـ oxygen والـ zinc كده.","screen_text":"O = oxygen · Zn = zinc"},{"id":"l5","visual":"Aha (hold ≥ 1.5 s): O and Zn dim; Fe card moves to centre at 100% (w 420). On cue l5 'ferrum' the word 'ferrum' (Cairo 900, 72) types out under the card with 'F' and 'e' gold, and two YK.arrow lines link those letters up to the card's 'Fe'; tag 'Latin' (48). Answers the l1 hook.","tts_text":"وساعات من الاسم الـ Latin: الـ iron اسمه ferrum، فبقى رمزه كده.","screen_text":"Fe = ferrum (Latin)"},{"id":"l6","style":"curious","visual":"Self-check on a new case (R8): YK.elementCard(ctx, 540, 1000, {sym:'Co', nameEn:'Cobalt', config:'', w:380}) with its symbol hidden (blank box) + two choice tiles below it at y 1380: 'Co' (left) and 'CO' (right) (mono 96). Question 'Cobalt: Co or CO?' (Cairo 900, 80) in the headline band on cue l6 'cobalt'. YK.checkPause(ctx, 540, 1600, {t, start: YK.cue('l6','فكّروا'), dur: YK.cue('l7') - that start, question:'', answer:''}) through the ≥ 1 s silence.","tts_text":"الـ cobalt، الحرف التاني بتاعه small ولا capital؟ فكّروا. <long pause>","screen_text":"Cobalt: Co or CO?"},{"id":"l7","visual":"Answer: on cue l7 'small' the 'Co' tile fills the card's symbol box + YK.rightMark (mint); on cue 'carbon' the 'CO' tile splits into two small tiles 'C' and 'O' with names 'Carbon' / 'Oxygen' (48) and a coral YK.wrongMark beside the tile; label 'CO = carbon + oxygen' (48). The right answer stays bigger and longer (G40). ✓/✕ are YK stamps, never text glyphs.","tts_text":"small. لو الاتنين capital يبقوا carbon و oxygen مع بعض.","screen_text":"Co ✓   CO = carbon + oxygen"},{"id":"l8","visual":"Voiced lock-in (S3): YK.takeaway({title:'Elements and their symbols', line:'One element, one kind of atom, one symbol.'}) from cue l8 start, held through the line + tail (≥ 2.5 s). Signals: 'atom' and 'symbol' pulse gold on their cues. Loop (S5): last 0.8 s returns to the Fe card of frame 0.","tts_text":"element واحد: نوع atom واحد، و symbol واحد.","screen_text":"One element, one kind of atom, one symbol."}],"logline":"An element is one kind of atom with a one- or two-letter symbol, first letter capital; some come from English names (O, Zn), some from Latin (Fe from ferrum), and the capitals matter: Co is cobalt, CO is two 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الـ iron مش جاي من كلمة iron خالص\nأومال جاي منين\nالـ element مادة نقية كل الـ atoms فيها\nنوع واحد\nوكل element ليه symbol حرف أو اتنين أولهم\ncapital دايمًا\nساعات الـ symbol من اسمه الإنجليزي زي الـ\noxygen والـ zinc كده\nوساعات من الاسم الـ Latin الـ iron اسمه\nferrum فبقى رمزه كده\nالـ cobalt الحرف التاني بتاعه small ولا\ncapital فكّروا\nsmall لو الاتنين capital يبقوا carbon و\noxygen مع بعض\nelement واحد نوع atom واحد و symbol واحد","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":9},{"id":"chem-s3-en.video-short-pt.groups-periods","kind":"short","version":1,"ord":11,"content_lang":"ar-EG","primary_concept_id":"pt.groups-periods","concepts":[{"concept_id":"pt.groups-periods","role":"primary"}],"title":"Periodic table: periods and groups","payload":{"title":"Periodic table: periods and groups","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): YK.periodicTable(ctx, 108, 820, 864, {highlight:{symbols:['Fe']}, hp:1, labels:{periods:true}, fBlock:false}) as a 2 s establishing shot with the Fe cell glowing gold and a slow push-in starting at t=0, + hook already on screen at t=0 (headline band, Cairo 1000 ~110): 'Fe: period 4. Why 4?'. Signals: Fe cell pulses on cue l1 'iron', row label '4' flashes on cue 'period'. At ≤ 2 s YK.camera crops to periods 1–4 (cells ≥ 48 px) — the full table is never held > 2 s (S10). Legibility (G11): cropped cells are ~48 px, so every cell we talk about (Fe here; Li, Na, K, Mg later) gets a 1.6× pop-out tile (symbol ≥ 56) over its cell; the rest of the table is a map.","tts_text":"الـ iron قاعد في period أربعة… ليه أربعة بالذات؟","screen_text":"Fe: period 4. Why 4?"},{"id":"l2","visual":"Cropped table (periods 1–4, all 18 columns, YK.camera). On cue l2 'atomic' a cyan cursor runs over cells in Z order 1 → 26 (H, He, Li… Fe), each cell's atomic number flashing as it passes (YK.prog over the line). Label 'Ordered by increasing atomic number' (56, lesson/book wording) under the table.","tts_text":"الجدول مترتّب بالـ atomic number، عنصر ورا عنصر.","screen_text":"Ordered by increasing atomic number"},{"id":"l3","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Main energy levels', {kind:'prereq', align:'center'}) at line start (≤ 2 s). On cue l3 'period' row 4 highlights (highlight periods:[4], hp tween); on cue 'energy' small YK.atom icons (size 70) appear at the left of rows 1–4 with 1, 2, 3, 4 rings. Label 'Period = row = number of energy levels' (48, 2 lines).","tts_text":"الـ period هو الصف، ورقمه هو عدد الـ energy levels في الـ atom بتاعه.","screen_text":"Period = row = number of energy levels"},{"id":"l4","visual":"Aha (hold ≥ 1.5 s): table dims to 35% and slides down (G17); YK.atom(ctx, 540, 900, {shells:[2,8,14,2], nucleusLabel:'Fe', size 300}) rises from the Fe cell; its four rings count 1-2-3-4 on cue 'أربع' (gold ring tags); on cue 'period' a YK.arrow links the outer ring to the row-4 label. YK.formula '_{26}Fe: 2, 8, 14, 2 → period 4' (mono 60). Answers the l1 hook. (Ch.1 p.8: the first transition series is in the fourth period.)","tts_text":"الـ iron عنده أربع levels، يبقى period أربعة.","screen_text":"₂₆Fe: 2, 8, 14, 2 → period 4"},{"id":"l5","visual":"Atom exits; table back to 100% (cropped). On cue l5 'group' column 1 highlights top → bottom (highlight groups:[1]) with tag 'Group IA' (48, book naming) above it; on cue 'main' the A-group columns (1, 2, 13-18) get a soft cyan underline and tag 'Main (A) groups' (48) while the B/VIII block in the middle stays grey (group VIII differs, book p.3); on cue 'similar' Li, Na, K pop out (1.6×) and pulse together in the same colour (H stays plain). Headline 'Group = column · Main (A) groups: similar properties' (56, 2 lines). Mg is NOT popped out here (it is the l6 check case).","tts_text":"والـ group هو العمود، وفي الـ main groups، عناصره ليها similar properties مع بعض.","screen_text":"Group = column · Main (A) groups: similar properties"},{"id":"l6","style":"curious","visual":"Self-check on a new case (R8, not shown before): table dims; YK.atom(ctx, 540, 1000, {shells:[2,8,2], nucleusLabel:'Mg', size 320}); YK.formula '_{12}Mg: 2, 8, 2' (mono 64) builds on the three spoken numbers. Question '₁₂Mg: 2, 8, 2 — which period?' (Cairo 900, 72) in the headline band on cue l6 'magnesium'. YK.checkPause(ctx, 540, 1580, {t, start: YK.cue('l6','فكّروا'), dur: YK.cue('l7') - that start, question:'', answer:''}) through the 2 s silence (pause_after_s).","tts_text":"طب الـ magnesium: اتنين، تمانية، اتنين. في أنهي period؟ فكّروا.","screen_text":"₁₂Mg: 2, 8, 2 — which period?","pause_after_s":2},{"id":"l7","visual":"Answer: on cue l7 'تلاتة' the three rings flash 1-2-3 + YK.rightMark; the table returns with the Mg cell (pop-out 1.6×) glowing gold in row 3 on cue 'levels', Fe still marked in row 4 for contrast. Label 'Period 3: 3 energy levels' (56).","tts_text":"في period تلاتة، عشان عنده تلات energy levels بس.","screen_text":"Period 3: 3 energy levels"},{"id":"l8","visual":"Voiced lock-in (S3): YK.takeaway({title:'Periodic table: periods and groups', line:'Period = row · Group = column'}) from cue l8 start, held through the line + the 1.5 s pause_after_s + tail (fully visible ≥ 3 s before the loop starts); behind it (35%) row 4 and column 1 cross-highlight on their cues. Loop (S5): only the last 0.8 s returns to the cropped table with Fe glowing as in frame 0.","tts_text":"الـ period صف، والـ group عمود.","screen_text":"Period = row · Group = column","pause_after_s":1.5}],"logline":"The periodic table is ordered by atomic number; a period is a row whose number equals the atom's energy levels (iron: 4 levels, period 4; magnesium: 3 levels, period 3), and in the main (A) groups a column holds elements with similar properties.","concept_ids":["pt.groups-periods"]},"layer":null,"layer_fallback":false,"images":{"cover_9x16":"https://cdn.yaani.ai/files/3ba6ca38fa28522ff85e1d10eabca74993db7ff18ae251b5d74d418f61d9de35.jpg","hero_21x9":"https://cdn.yaani.ai/files/6a62b03634e7c9705958896e1864dcaf979391b67220e0b6061580125d7468e5.jpg","hero_4x5":"https://cdn.yaani.ai/files/d55a37072ef607699c58671ce26037347fd7c6dd5e8ac4785fbe6302ec810175.jpg","og":"https://cdn.yaani.ai/files/f6b1bbfdd347db91d60800491eb4f68b9e57531ad26f426661d17dc7fac8dd4e.jpg","poster":"https://cdn.yaani.ai/files/7d4238665a4c1a00cfe5bc903b00f5e0301ccb8dda7f3f55ed7d20009218ba43.jpg","thumbnail":"https://cdn.yaani.ai/files/2c41eef910484999409fb934474cf3e12b75fac3c4de7bd789dcfa595c46014a.jpg"},"thumbnail_variant":"a","files":[{"role":"captions","key":"ar-EG","url":"https://cdn.yaani.ai/files/8e3b9989716e2d88fca3703d54b5af5a1a86e3e12842ba14990766af660db381.vtt","mime":"text/vtt","size":900},{"role":"cover_9x16","key":"","url":"https://cdn.yaani.ai/files/3ba6ca38fa28522ff85e1d10eabca74993db7ff18ae251b5d74d418f61d9de35.jpg","mime":"image/jpeg","size":117545},{"role":"cover_9x16","key":"a/1080x1920.avif","url":"https://cdn.yaani.ai/files/cb6c78c454d06bacb9070141fc6460a88676126807f371809b86a01e67b63658.avif","mime":"image/avif","size":15525},{"role":"cover_9x16","key":"a/1080x1920.jpg","url":"https://cdn.yaani.ai/files/3ba6ca38fa28522ff85e1d10eabca74993db7ff18ae251b5d74d418f61d9de35.jpg","mime":"image/jpeg","size":117545},{"role":"cover_9x16","key":"a/1080x1920.png","url":"https://cdn.yaani.ai/files/1a41953dab236a3845f5a25cd7ba812f8138f1d7143d3c8bf8071ac0879bc386.png","mime":"image/png","size":309732},{"role":"cover_9x16","key":"a/1080x1920.webp","url":"https://cdn.yaani.ai/files/775e2ef127171661abefa2243781e6deb8e8e063c7bbae8e8643d5df15d4f056.webp","mime":"image/webp","size":34056},{"role":"cover_9x16","key":"a/540x960.avif","url":"https://cdn.yaani.ai/files/f99d5bd025e020e2e14f8d1c2ed4b34dfc1096cbbdb5917239f20dffdeed6d7f.avif","mime":"image/avif","size":8584},{"role":"cover_9x16","key":"a/540x960.jpg","url":"https://cdn.yaani.ai/files/d21e0521420cb537741a518d0f965828e972cf7ce28a47c9972a15fd8d4cd4ac.jpg","mime":"image/jpeg","size":49646},{"role":"cover_9x16","key":"a/540x960.webp","url":"https://cdn.yaani.ai/files/a3e48241615af68d48755bea2cba39a2d8f6dc01bfba188a3874cf3f525a8962.webp","mime":"image/webp","size":15450},{"role":"hero_21x9","key":"","url":"https://cdn.yaani.ai/files/6a62b03634e7c9705958896e1864dcaf979391b67220e0b6061580125d7468e5.jpg","mime":"image/jpeg","size":114495},{"role":"hero_21x9","key":"a/1680x720.avif","url":"https://cdn.yaani.ai/files/64cb7845bc4e6e1e58bd4e402cbf4cb45579ac19f2839c1abfc0216cce02802a.avif","mime":"image/avif","size":10121},{"role":"hero_21x9","key":"a/1680x720.jpg","url":"https://cdn.yaani.ai/files/d9fe8a92c4cb997c2288281b4e7e056eb1eb0996c2e3c649742e7aa9034771d6.jpg","mime":"image/jpeg","size":68440},{"role":"hero_21x9","key":"a/1680x720.webp","url":"https://cdn.yaani.ai/files/8685e5f2225d4f5e75af0854327cba35ef4637bc7a71875c2bc7b23575dcc732.webp","mime":"image/webp","size":19734},{"role":"hero_21x9","key":"a/2520x1080.avif","url":"https://cdn.yaani.ai/files/90c4060d12a437a42c24c935ac2207c80062269d26d1707e844d77c103d4ed0f.avif","mime":"image/avif","size":14402},{"role":"hero_21x9","key":"a/2520x1080.jpg","url":"https://cdn.yaani.ai/files/6a62b03634e7c9705958896e1864dcaf979391b67220e0b6061580125d7468e5.jpg","mime":"image/jpeg","size":114495},{"role":"hero_21x9","key":"a/2520x1080.png","url":"https://cdn.yaani.ai/files/462ea7d7e599cc9db50f416fdc82cf9fd925687aef1647826fc0557f83732cdd.png","mime":"image/png","size":266071},{"role":"hero_21x9","key":"a/2520x1080.webp","url":"https://cdn.yaani.ai/files/6b533a3b96353dbbbfcce2facb7df813ae3402eae87b511b4c7725f68422b5e3.webp","mime":"image/webp","size":31474},{"role":"hero_4x5","key":"","url":"https://cdn.yaani.ai/files/d55a37072ef607699c58671ce26037347fd7c6dd5e8ac4785fbe6302ec810175.jpg","mime":"image/jpeg","size":91967},{"role":"hero_4x5","key":"a/1080x1350.avif","url":"https://cdn.yaani.ai/files/0ac024877982f19f6c139eb13ff28dda025a81773b741cd47a3b0acc59fd2233.avif","mime":"image/avif","size":13135},{"role":"hero_4x5","key":"a/1080x1350.jpg","url":"https://cdn.yaani.ai/files/d55a37072ef607699c58671ce26037347fd7c6dd5e8ac4785fbe6302ec810175.jpg","mime":"image/jpeg","size":91967},{"role":"hero_4x5","key":"a/1080x1350.png","url":"https://cdn.yaani.ai/files/39142479b36dd17bc84409048a9c040a1b49845379b67ae9b38ffa5acdc9c1fd.png","mime":"image/png","size":217587},{"role":"hero_4x5","key":"a/1080x1350.webp","url":"https://cdn.yaani.ai/files/501b57fd723b82b0b993f52038fe6cf054e1b287c17f8144ba0a17a3911619aa.webp","mime":"image/webp","size":26554},{"role":"hero_4x5","key":"a/720x900.avif","url":"https://cdn.yaani.ai/files/ceb47fc2d15939048c1440d89aa05014ea4721cd8bd3f020336adaa272c00f04.avif","mime":"image/avif","size":9437},{"role":"hero_4x5","key":"a/720x900.jpg","url":"https://cdn.yaani.ai/files/d7e7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iron قاعد في period أربعة ليه أربعة\nبالذات\nالجدول مترتّب بالـ atomic number عنصر ورا\nعنصر\nالـ period هو الصف ورقمه هو عدد الـ energy\nlevels في الـ atom بتاعه\nالـ iron عنده أربع levels يبقى period\nأربعة\nوالـ group هو العمود وفي الـ main groups\nعناصره ليها similar properties مع بعض\nطب الـ magnesium اتنين تمانية اتنين في\nأنهي period فكّروا\nفي period تلاتة عشان عنده تلات energy\nlevels بس\nالـ period صف والـ group عمود","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":10},{"id":"chem-s3-en.video-short-atom.sublevels","kind":"short","version":1,"ord":13,"content_lang":"ar-EG","primary_concept_id":"atom.sublevels","concepts":[{"concept_id":"atom.sublevels","role":"primary"}],"title":"Energy sublevels (s, p, d, f)","payload":{"title":"Energy sublevels (s, p, d, f)","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): YK.dBlockZoom at p=1 (Sc–Zn strip, 2 rows, stripY 1050) with a counter sweeping 1 → 10 across the tiles (gold numbers, one per 0.2 s, looping) + hook already on screen at t=0 (headline band, Cairo 1000 ~110): 'Why 10 transition elements per row?'. Signals: strip glows violet on cue l1 'transition', the '10' pulses gold on cue 'عشرة'.","tts_text":"ليه الـ transition elements عشرة في كل صف؟","screen_text":"Why 10 transition elements per row?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Main energy levels', {kind:'prereq', align:'center'}) at line start (≤ 2 s). Strip dims and exits up; a wide bar 'n = 3' (Cairo 56) at y 900 on cue l2 'main'; on cue 'sublevels' it splits into three shorter bars side by side (YK.tween, 0.4 s) labelled '3s', '3p', '3d' (YK.label 56). Label 'Main level → sublevels' (56).","tts_text":"كل main energy level جواه sublevels أصغر.","screen_text":"Main level → sublevels"},{"id":"l3","visual":"A staircase builds top → bottom (y 700–1400, x 108–972): row 'n = 1' with one bar '1s' on cue l3 'one', row 'n = 2' with '2s 2p' on cue 'two'. Each row: number of bars = n.","tts_text":"الأول one s، والتاني two s و two p كمان.","screen_text":"n = 1: 1s · n = 2: 2s 2p"},{"id":"l4","visual":"Row 'n = 3' with '3s 3p 3d' appears under rows 1–2 on cue l4 'three' (first); the '3d' bar glows violet on the last 'three'. Staircase complete: each row has n bars.","tts_text":"والتالت three s و three p و three d كمان.","screen_text":"n = 3: 3s 3p 3d"},{"id":"l5","visual":"Myth beat (concept misconception, R11, G40). Small wrong staircase first (60% size, y 620–900, coral): rows n = 1 and n = 2 each drawn with four bars s p d f, label 'Every level has s, p, d, f' (48, coral); on cue 'غلط' YK.wrongMark and the '1d', '2d' bars crack and fall (0.4 s), then it exits. On cue 'تلاتة' the correct staircase from l3–l4 (full size, y 800–1450) returns with YK.rightMark (mint) and '3d' glowing; tag 'd starts at n = 3' (48, mint). The right version stays bigger and longer.","tts_text":"ناس فاكرة كل level فيه الأربع sublevels… غلط، الـ d sublevel بيبدأ من level تلاتة.","screen_text":"1d, 2d ✕   d starts at n = 3 ✓"},{"id":"l6","visual":"Aha (hold ≥ 1.5 s): the '3d' bar from the staircase grows into one wide bar (750 px, y 760) with 10 empty electron slots (no boxes: orbitals are the next concept); slots fill left → right, and each arriving electron lights one tile of the Sc–Zn strip below (YK.dBlockZoom p=1, stripY 1250, stripW 864): Sc on cue 'scandium', Zn on cue 'zinc'. Headline YK.formula '3d: 10 electrons → Sc … Zn' (mono 60). The l5 tag exits (≤ 2 text blocks). Book Ch.1 p.3: the d sublevel can take up to ten electrons, so ten vertical columns. No energy ordering (G43).","tts_text":"والـ three d بياخد عشرة، فعشر عناصر من الـ scandium للـ zinc بالظبط.","screen_text":"3d holds 10 → Sc to Zn"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8): staircase rows 1–3 dimmed 35%; an empty row 'n = 4' with a '?' bar at y 1300. Question 'Level n = 4: how many sublevels?' (Cairo 900, 72) in the headline band on cue l7 'الرابع'. YK.checkPause(ctx, 540, 1580, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the ≥ 1 s silence.","tts_text":"الـ level الرابع، فيه كام sublevel؟ فكّروا. <long pause>","screen_text":"Level n = 4: how many sublevels?"},{"id":"l8","visual":"Answer: the n = 4 row splits into four bars left → right from cue l8 'four' (first) to 'four' (second) (YK.label 56: 4s, 4p, 4d, 4f; 4f amber, the first f) + YK.rightMark; tag '4 sublevels = n' (48).","tts_text":"أربعة: من four s لحد four f، على قد رقمه.","screen_text":"4 sublevels: 4s → 4f"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Energy sublevels (s, p, d, f)', line:'Main level n has n sublevels.'}) from cue l9 start, held through the line + tail (≥ 2.5 s); staircase dimmed 35% behind it. Loop (S5): last 0.8 s returns to the Sc–Zn strip with the 1 → 10 counter of frame 0.","tts_text":"رقم الـ level هو عدد الـ sublevels جواه.","screen_text":"Main level n has n sublevels."}],"logline":"Each main level n splits into n sublevels; s holds 2, p 6, d 10, and d first appears at n = 3, which is why each transition series has ten 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الـ transition elements عشرة في كل صف\nكل main energy level جواه sublevels أصغر\nالأول one s والتاني two s و two p كمان\nوالتالت three s و three p و three d كمان\nناس فاكرة كل level فيه الأربع sublevels\nغلط الـ d sublevel بيبدأ من level تلاتة\nوالـ three d بياخد عشرة فعشر عناصر من الـ\nscandium للـ zinc بالظبط\nالـ level الرابع فيه كام sublevel فكّروا\nأربعة من four s لحد four f على قد رقمه\nرقم الـ level هو عدد الـ sublevels جواه","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":11},{"id":"chem-s3-en.video-short-atom.orbitals","kind":"short","version":1,"ord":15,"content_lang":"ar-EG","primary_concept_id":"atom.orbitals","concepts":[{"concept_id":"atom.orbitals","role":"primary"}],"title":"Orbitals","payload":{"title":"Orbitals","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): YK.electronBoxes(ctx, 540, 1050, {boxes:5, electrons:0, size:150, label:'3d'}) (750 px) + ten cyan electron dots circling above it (YK.rng phases, y 760–880) + hook already on screen at t=0 (headline band, Cairo 1000 ~100, 2 lines): '10 electrons.' / 'Only 5 boxes?'. Signals: dots flash on cue l1 'electrons', box rims flash on cue 'boxes'.","tts_text":"الـ d sublevel بياخد عشرة electrons… بس بنرسمه خمس boxes بس! ليه؟","screen_text":"10 electrons. Only 5 boxes?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Energy sublevels (s, p, d, f)', {kind:'prereq', align:'center'}) at line start (≤ 2 s). On cue l2 'orbitals' the 5 boxes separate slightly (gap 0→20) and each gets a small tag 'orbital' above it in sequence; label '1 box = 1 orbital' (56) on cue 'box'.","tts_text":"كل sublevel متقسّم orbitals، وكل box بنرسمه هو orbital واحد.","screen_text":"Sublevel = orbitals · 1 box = 1 orbital"},{"id":"l3","visual":"Myth beat (concept misconception, R11, G40). The 5-box row dims to 35% and slides up (y 760) behind it. Small wrong picture (60% size, y 900–1160) on cue l3 'circular': a nucleus with a thin coral circular track and an electron running on it, label 'Circular path' (48, coral).","tts_text":"ناس فاكرة الـ orbital ده circular path، الـ electron بيلف فيه.","screen_text":"Circular path ✕"},{"id":"l4","visual":"YK.wrongMark on the circular-path picture on cue l4 'غلط'; it exits 0.4 s later. On cue 'region' the correct picture, bigger (y 900–1450): a soft cyan cloud (radial gradient, seeded dots denser near the centre, no shape detail — d-orbital shapes are out of scope, G46) around a nucleus, label 'Region of space' (56, mint) + YK.rightMark. Book-level definition only; no shapes. The cloud exits at line end and the 5-box row returns to y 1050 at 100%.","tts_text":"غلط، ده region of space، الـ electron غالبًا بيكون فيها.","screen_text":"Region of space ✓"},{"id":"l5","visual":"Box 1 zooms (YK.camera 0.8 s) on cue l5 'orbital': YK.electronBoxes(ctx, …, {boxes:1, electrons:2, fill: prog from cue 'orbital' over 0.8 s}) puts ↑ then ↓; on cue 'بالكتير' a third cyan dot arcs in, bounces off the rim (coral rim flash) and leaves. Label 'max 2 electrons' (56) on cue 'اتنين'.","tts_text":"والـ orbital الواحد ياخد اتنين electrons بالكتير.","screen_text":"1 orbital: max 2 electrons"},{"id":"l6","visual":"Aha (hold ≥ 1.5 s): camera back; the ten hovering dots drop into the 5 boxes in pairs (↑↓, fill 0→1 from cue 'خمس' to cue 'عشرة'); YK.formula '5 × 2 = !{10}' (mono 96) under the row on cue 'عشرة'. Answers the l1 hook. (Ch.1 p.8 point 1: the five orbitals of the 3d sublevel.)","tts_text":"الـ d sublevel: خمس orbitals، كل واحد اتنين، يبقوا عشرة.","screen_text":"d: 5 orbitals × 2 = 10"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8): YK.electronBoxes(ctx, 540, 1050, {boxes:3, electrons:0, size:150, label:'2p', arrowStyle:'full'}) drawn hidden (boxes masked by a '?' panel) + six cyan dots above. Question 'p holds 6 electrons. How many orbitals?' (Cairo 900, 72) in the headline band on cue l7 'ستة'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the ≥ 1 s silence.","tts_text":"طب الـ p sublevel بياخد ستة electrons. فيه كام orbital؟ فكّروا. <long pause>","screen_text":"p holds 6 electrons. How many orbitals?"},{"id":"l8","visual":"Answer: on cue l8 'تلاتة' the mask lifts on 3 boxes + YK.rightMark; the six dots drop in as pairs on cue 'ستة'; YK.formula '6 ÷ 2 = !{3}' (mono 80) and tag 's: 1 · p: 3 · d: 5' (48) under the row.","tts_text":"تلاتة orbitals: ستة على اتنين.","screen_text":"3 orbitals: 6 ÷ 2"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Orbitals', line:'Each orbital holds at most 2 electrons.', }) from cue l9 start, held through the line + tail (≥ 2.5 s). Signal: '2 electrons' pulses gold on cue 'اتنين'. Loop (S5): last 0.8 s returns to the 5-box d row of frame 0, now filled ↑↓ ×5.","tts_text":"كل orbital: اتنين electrons بالكتير.","screen_text":"Each orbital holds at most 2 electrons."}],"logline":"The d sublevel holds 10 electrons but is drawn as 5 boxes: each box is one orbital, and an orbital holds at most 2 electrons; s has 1 orbital, p 3, d 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d sublevel بياخد عشرة electrons بس\nبنرسمه خمس boxes بس ليه\nكل sublevel متقسّم orbitals وكل box بنرسمه\nهو orbital واحد\nناس فاكرة الـ orbital ده circular path الـ\nelectron بيلف فيه\nغلط ده region of space الـ electron غالبًا\nبيكون فيها\nوالـ orbital الواحد ياخد اتنين electrons\nبالكتير\nالـ d sublevel خمس orbitals كل واحد اتنين\nيبقوا عشرة\nطب الـ p sublevel بياخد ستة electrons فيه\nكام orbital فكّروا\nتلاتة orbitals ستة على اتنين\nكل orbital اتنين electrons بالكتير","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":12},{"id":"chem-s3-en.video-short-atom.aufbau","kind":"short","version":1,"ord":17,"content_lang":"ar-EG","primary_concept_id":"atom.aufbau","concepts":[{"concept_id":"atom.aufbau","role":"primary"}],"title":"Aufbau principle (order of filling)","payload":{"title":"Aufbau principle (order of filling)","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): two sublevel rows side by side at y 1050, YK.electronBoxes 4s (1 box, size 130, left, x ≈ 260) and 3d (5 boxes, size 110, right), with one cyan electron dot bouncing between them undecided (deterministic sine path) + hook already on screen at t=0 (headline band, Cairo 1000 ~110): '3 < 4. So 3d first?'. Signals: '3 < 4' pulses on cue l1 'تلاتة'; the 3d row rim flashes on cue 'three'.","tts_text":"تلاتة أصغر من أربعة… يبقى three d تتملي الأول؟","screen_text":"3 < 4. So 3d first?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Orbitals', {kind:'prereq', align:'center'}) at line start (≤ 2 s). The two rows slide down and dim (35%). On cue l2 'Aufbau' term label 'Aufbau principle' (Cairo 900, 72) in the headline band; on cue 'بالترتيب' a vertical YK.flow (layout 'col', area x 300–780, y 720–1600) of sublevel tiles appears empty, top → bottom: 1s, 2s, 2p, 3s, 3p, ?, ? (tiles 64 px text). No energy axis (G43).","tts_text":"Aufbau principle: الـ electrons بتملا الـ sublevels بالترتيب.","screen_text":"Aufbau principle: fill in order"},{"id":"l3","visual":"Each tile fills (cyan) and its YK.flow arrow lights on its spoken label cue ('one', 'two', 'two', 'three', 'three'); a small electron counter beside the column rises 2 → 4 → 10 → 12 → 18. Label '1s → 2s → 2p → 3s → 3p' = the column itself.","tts_text":"one s، two s، two p، three s، three p… طبيعي.","screen_text":"1s → 2s → 2p → 3s → 3p"},{"id":"l4","visual":"Aha part 1: the two '?' tiles resolve on cues: '4s' on cue 'four' (gold flash, fills), '3d' on the second 'three' of l4 (violet), then a faint '4p' tile below. The column now reads 1s 2s 2p 3s 3p 4s 3d 4p (the book filling order, no energy claim, G43).","tts_text":"بعد three p ييجي four s، والـ three d بعده.","screen_text":"… 3p → 4s → 3d → 4p"},{"id":"l5","visual":"Myth beat (concept misconception, R11, G40). Small wrong column first (60% size, left, coral): 3p → 3d → 4s, label '3d before 4s' (48, coral) with '3 < 4' tag; YK.wrongMark on cue 'غلط'; it exits 0.4 s later. On cue 'four' the correct column (full size) pulses its 3p → 4s → 3d arrows + YK.rightMark (mint), label '4s before 3d' (48, mint). The right version stays bigger and longer.","tts_text":"ناس بتبدأ بالـ three d عشان تلاتة أصغر… غلط، four s الأول.","screen_text":"3d before 4s (3 < 4) ✕   4s before 3d ✓"},{"id":"l6","visual":"Aha part 2 (hold ≥ 1.5 s): the l3 column's filled tiles 1s → 3p collapse into one chip '[Ar]' with tag '[Ar] = 1s 2s 2p 3s 3p' (48) for ~1 s (links the column to the strip's core chip, R16); then YK.configStrip(ctx, 540, 1100, {Z:21, step: 2→3, size:100, label:'none'}): Ca's 4s ↑↓ with YK.formula '_{20}Ca: 4s^2' + tag 'full' on cue 'calcium', then one cyan ↑ arcs into 3d box 1 on cue 'scandium' with YK.formula '_{21}Sc: 3d^1' (mono 64). Book Ch.1 p.8: first series in the fourth period after calcium [Ar] 4s²; ₂₁Sc [Ar] 4s² 3d¹. Answers the l1 hook.","tts_text":"الـ calcium يقفل four s، والـ scandium يبدأ three d بعده.","screen_text":"₂₀Ca: 4s² full → ₂₁Sc: 3d¹"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8): YK.configStrip(ctx, 540, 1100, {Z:19, step:0, size:100, label:'none'}) empty, one cyan dot hovering above between 4s and 3d. Question '₁₉K: last electron → 3d or 4s?' (Cairo 900, 72) in the headline band on cue l7 'potassium'. YK.checkPause(ctx, 540, 1580, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the ≥ 1 s silence.","tts_text":"الـ potassium: تسعتاشر electron. الأخير يروح three d ولا four s؟ فكّروا. <long pause>","screen_text":"₁₉K: last electron → 3d or 4s?"},{"id":"l8","visual":"Answer: on cue l8 'four' the dot arcs into the 4s box (step 0→1) + YK.rightMark; YK.formula '_{19}K: 4s^1' (mono 64); on cue 'three' the empty 3d boxes flash once (still empty).","tts_text":"four s، مش three d… زي الترتيب.","screen_text":"4s¹, not 3d¹"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Aufbau principle (order of filling)', line:'Fill in order: 4s before 3d.', formula:'3p -> 4s -> 3d'}) from cue l9 start, held through the line + tail (≥ 2.5 s) (the full 8-sublevel order does not fit the card at ≥ 56 px); signals: '4s' pulses gold on cue 'four', '3d' violet on cue 'three'. Loop (S5): last 0.8 s returns to the 4s / 3d rows of frame 0, the electron now settled in 4s.","tts_text":"four s الأول، وبعدها three d، مش العكس.","screen_text":"Fill in order: 4s before 3d."}],"logline":"Electrons fill sublevels one by one in a fixed order, 1s 2s 2p 3s 3p 4s 3d 4p; 3 < 4 does not mean 3d first: 4s fills before 3d, so calcium closes 4s and scandium starts 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أصغر من أربعة يبقى three d تتملي\nالأول\nAufbau principle الـ electrons بتملا الـ\nsublevels بالترتيب\none s two s two p three s three p طبيعي\nبعد three p ييجي four s والـ three d بعده\nناس بتبدأ بالـ three d عشان تلاتة أصغر غلط\nfour s الأول\nالـ calcium يقفل four s والـ scandium يبدأ\nthree d بعده\nالـ potassium تسعتاشر electron الأخير يروح\nthree d ولا four s فكّروا\nfour s مش three d زي الترتيب\nfour s الأول وبعدها three d مش العكس","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":13},{"id":"chem-s3-en.video-short-phys.magnetic-field","kind":"short","version":1,"ord":19,"content_lang":"ar-EG","primary_concept_id":"phys.magnetic-field","concepts":[{"concept_id":"phys.magnetic-field","role":"primary"}],"title":"Magnets and magnetic fields","payload":{"title":"Magnets and magnetic fields","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): a grey steel plate (fridge door, YK.roundRect x 120-300, y 760-1340, steel gradient) on the left; a bar magnet YK.magnet({type:'bar', size:360, field:0}) stuck flat on it at (440, 1050); an aluminium can YK.icon('can', 780, 1050, 280, steel) on the right with a clear gap. The magnet gives a small deterministic tug toward the can (+-8 px sine) and the can never moves. Hook on screen at t=0 in the band (Cairo 1000 ~100, <= 2 lines): 'Aluminium can: no pull. Why?'. Signals: magnet glows on cue l1 'magnet' (after the tts fix; until then cue word 0), plate rim flashes on 'بيلزق', can rim flashes coral on 'aluminium' (the word is in the hook, no extra label).","tts_text":"الـ magnet بيلزق في التلاجة… بس علبة الـ aluminium لأ! ليه؟","screen_text":"Aluminum can: no pull. Why?"},{"id":"l2","visual":"Hook exits on cue l2 'magnet'; plate and can exit. The magnet moves to (540, 960), size 520. Field lines draw in on cue 'magnetic' (YK.magnet field: YK.prog from cue 'magnetic' over 1 s; kit lines are cyan, dashed, flowing with t). On cue 'field' YK.termCard({term:'Magnetic field', def:'The region around a magnet where its magnetic force acts.', keys:['region']}) slides in at y 1380-1660 (lesson KeyTerm wording); 'region' highlights on cue 'region'. Band empty this line (the card is the text, G16). No iron filings (decoration).","tts_text":"حوالين الـ magnet فيه magnetic field: region بتأثر فيها قوته.","screen_text":"Magnetic field: the region around a magnet where its magnetic force acts"},{"id":"l3","visual":"Card exits; band empty. Two rows of two bar magnets, top -> bottom (S9), each YK.magnet size 300, field 0 (kit: N coral, S blue, letters drawn upright). Row 1 at y 860: left angle Math.PI (reads S|N) + right angle 0 (reads N|S), so N faces N. On cue l3 'like' both N ends glow; on 'repel' they slide 80 px apart with an outward coral YK.arrow pair; label 'Like poles repel' (52) under row 1. Row 2 at y 1260: both angle Math.PI (S|N  S|N), so N faces S; on 'unlike' the facing ends glow; on 'attract' inward mint arrows and the gap closes; label 'Unlike poles attract' (52).","tts_text":"الـ like poles بتعمل repel، والـ unlike بتعمل attract لبعض.","screen_text":"Like poles repel; unlike poles attract"},{"id":"l4","visual":"Myth beat (concept misconception 'Magnets attract all metals', R11, G40). Small wrong picture (60%, y 820-1240, coral tint): one magnet (size 240) with coral arrows pulling three metal icons YK.icon 'can', 'coin', 'cable' (140 px each) toward it; label 'Attracts all metals' (48, coral) on cue l4 'metals'; YK.wrongMark on cue 'غلط'; the picture exits 0.4 s later.","tts_text":"ناس فاكرة إن الـ magnet بيشد كل الـ metals… غلط.","screen_text":"Attracts all metals ✕"},{"id":"l5","visual":"Aha (hold >= 1.5 s), answers the hook: the l2 magnet (size 420, field on) at (540, 860). Three metal chunks YK.sphere(ctx, x, 1250, 70, steel) at x 260 / 540 / 820 with labels 'iron', 'cobalt', 'nickel' (48) under them (no element cards: elementCard < 380 px puts text under 40 px). Each chunk slides up toward the magnet with a mint arrow on its spoken cue ('iron', 'cobalt', 'nickel'); YK.rightMark (90) after 'nickel'. On cue 'aluminium' the l1 can (YK.icon 'can', 200) enters at (540, 1540), stays still, small YK.wrongMark (80) + label 'aluminium' (48).","tts_text":"بيشد بقوة الـ iron والـ cobalt والـ nickel… والـ aluminium لأ.","screen_text":"Iron, cobalt, nickel ✓ · aluminum ✕"},{"id":"l6","style":"curious","visual":"Self-check on a new case (R8: copper not shown so far): magnet (size 420, field on) at (540, 860); a copper wire coil YK.icon('cable', 540, 1240, 260, '#C8794A'), no arrows. Question 'A copper wire near a magnet: strongly pulled?' (Cairo 900, 72, <= 2 lines) in the band on cue l6 'copper'. YK.checkPause(ctx, 540, 1540, {t, start: YK.cue('l6','فكّروا'), dur: YK.cue('l7') - that start, question:'', answer:''}) through the stitched silence (the trailing <long pause> is stripped; pause_after_s default 1.5 s, so the ring runs >= 1.5 s); ring exits at cue l7 + 0.5 s.","tts_text":"طب سلك copper جنب الـ magnet… هيتشد بقوة؟ فكّروا. <long pause>","screen_text":"A copper wire near a magnet: strongly pulled?"},{"id":"l7","visual":"Answer: question leaves the band on cue l7 'لأ'; the wire stays put (4 px wobble only, no arrow). On cue 'metal' label 'No: copper is a metal, but not noticeably pulled' (52, <= 2 lines) at y 1480 + one YK.rightMark at its left. Nothing else on screen (G16).","tts_text":"لأ، الـ copper ده metal، بس مش بيتشد بشكل ملحوظ.","screen_text":"No: copper is a metal, but not noticeably pulled"},{"id":"l8","visual":"Voiced lock-in (S3): YK.takeaway({title:'Magnets and magnetic fields', line:'A magnet does not attract all metals.', t, pulse:[{word:'not', at:YK.cue('l8','مبيشدش')}, {word:'all', at:YK.cue('l8','metals')}, {word:'metals', at:YK.cue('l8','metals')}]}) from cue l8 start, held through the line + tail (>= 2.5 s). Loop (S5): last 0.8 s the card exits and the frame-0 composition returns (magnet on the plate, still can).","tts_text":"الـ magnet مبيشدش كل الـ metals، خلّي بالك.","screen_text":"A magnet does not attract all metals."}],"logline":"A magnet's field strongly pulls iron, cobalt and nickel but not every metal: an aluminum can or a copper wire stays put; like poles repel, unlike poles 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magnet بيلزق في التلاجة بس علبة الـ\naluminium لأ ليه\nحوالين الـ magnet فيه magnetic field\nregion بتأثر فيها قوته\nالـ like poles بتعمل repel والـ unlike\nبتعمل attract لبعض\nناس فاكرة إن الـ magnet بيشد كل الـ metals\nغلط\nبيشد بقوة الـ iron والـ cobalt والـ nickel\nوالـ aluminium لأ\nطب سلك copper جنب الـ magnet هيتشد بقوة\nفكّروا\nلأ الـ copper ده metal بس مش بيتشد بشكل\nملحوظ\nالـ magnet مبيشدش كل الـ metals خلّي بالك","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":14},{"id":"chem-s3-en.video-short-atom.electron-spin-pauli","kind":"short","version":1,"ord":21,"content_lang":"ar-EG","primary_concept_id":"atom.electron-spin-pauli","concepts":[{"concept_id":"atom.electron-spin-pauli","role":"primary"}],"title":"Electron spin and the Pauli principle","payload":{"title":"Electron spin and the Pauli principle","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): one orbital box YK.electronBoxes(ctx, 540, 1050, {boxes:1, electrons:0, size:300}) with two YK.spinArrow drawn by the page (↑ cyan at x 492, ↓ pink at x 588, 186 px tall) bobbing +-8 px in opposite phase (sine) + hook on screen at t=0 in the band (Cairo 1000 ~110): 'Why ↑↓ in one orbital?'. Signals: box rim flashes on cue l1 'orbital'; ↑ pulses on 'لفوق', ↓ on 'لتحت'. Label 'orbital' (48) under the box on cue 'orbital'.","tts_text":"ليه في الـ orbital الواحد سهم لفوق وسهم لتحت؟","screen_text":"Why ↑↓ in one orbital?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Magnets and magnetic fields', {kind:'prereq', align:'center'}) for <= 2 s from line start (the short's only chip). Hook exits; the box zooms out (YK.camera 0.8 s). One cyan electron YK.sphere (r 120) at (540, 1000) on cue l2 'electron'; on cue 'spin' a curved rotation arrow (ctx.arc 300 deg, r 165, + YK.arrow head; NOT YK.spinArrow, which is the ↑ glyph) turns around it. On cue 'magnet' a mini bar magnet YK.magnet({size:200, angle:-Math.PI/2, field: prog over 0.8 s}) fades in through the sphere (N up). Label 'Electron spin → a tiny magnet' (52) at y 1400.","tts_text":"كل electron بيعمل spin حوالين نفسه، فبيبقى زي magnet صغير.","screen_text":"Electron spin → a tiny magnet"},{"id":"l3","visual":"Two cyan electron spheres (r 100) at x 340 / 740, y 1000, each with its mini magnet (YK.magnet size 160, field 0.6): left angle -Math.PI/2 (N up), right Math.PI/2 (N down). YK.spinArrow ↑ (cyan, 120 px) above the left on cue 'لفوق', ↓ (pink) above the right on 'لتحت'. Both spheres stay the same cyan: ↓ is the same electron spinning the other way, shown, not written (no extra tag, G16). Label 'Two spin directions: ↑ and ↓' (52) at y 1400 on cue l3 'spin'.","tts_text":"والـ spin ليه اتجاهين بس، سهم لفوق أو لتحت.","screen_text":"Two spin directions: ↑ and ↓"},{"id":"l4","visual":"No second chip (G16; the l2 chip is the short's prereq link). The spheres shrink into their arrows and drop into one box: YK.electronBoxes(ctx, 540, 1000, {boxes:1, electrons:2, fill: prog from cue 'اتنين' over 0.6 s, size:260}). Term 'Pauli principle' (Cairo 1000, 80) in the band on cue l4 'Pauli'. On cue 'بالكتير' a third cyan arrow arcs in, bounces off the rim (coral flash) and leaves. On cue 'opposite' ↑ and ↓ flash gold together; label 'max 2, opposite spins (↑↓)' (52) under the box.","tts_text":"الـ Pauli principle: الـ orbital ياخد اتنين بالكتير، والـ spins opposite لبعض.","screen_text":"Pauli principle: one orbital holds max 2, opposite spins (↑↓)"},{"id":"l5","visual":"Aha (hold >= 1.5 s), answers the hook. The ↑↓ box (size 300) at (540, 1000); on cue 'magnets' a mini magnet (YK.magnet size 140) appears on each arrow, N up on ↑ and N down on ↓; on cue 'magnetic' both field patterns fade 1 -> 0 over 1 s (YK.magnet field option). Label '↑↓: the magnetic effects cancel' (56) at y 1400 on cue 'effects'. No extra 'net effect' tag (G16).","tts_text":"اتنين magnets صغيرين عكس بعض، فالـ magnetic effects بتلغي بعض.","screen_text":"↑↓: the magnetic effects cancel"},{"id":"l6","visual":"Two boxes (size 220): left the ↑↓ box at x 330 (field off, dim 50%), right a box with one ↑ only at x 750 (YK.electronBoxes electrons:1). On cue l6 'electron' the single ↑ glows; on cue 'unpaired' its mini magnet (YK.magnet size 140, angle -Math.PI/2) shows field 1, dashes flowing (not cancelled). Label 'unpaired electron: effect not cancelled' (52, 'unpaired' gold) at y 1400. (Ch.1 pp.13-14: unpaired electrons give a magnetic field from their spin.)","tts_text":"بس الـ electron اللي لوحده، unpaired، تأثيره بيفضل.","screen_text":"↑ unpaired electron: effect not cancelled"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8: ↑↑ not shown so far): one box YK.electronBoxes(ctx, 540, 1000, {boxes:1, electrons:0, size:260}) with two ↑ YK.spinArrow drawn by the page at +-48 px (the kit cannot put ↑↑ in one box), no marks. Question 'Two electrons in one orbital, both ↑↑: allowed?' (Cairo 900, 72, <= 2 lines) in the band on cue l7 'electrons'. YK.checkPause(ctx, 540, 1540, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (the trailing <long pause> is stripped; pause_after_s default 1.5 s, so the ring runs >= 1.5 s); ring exits at cue l8 + 0.5 s.","tts_text":"طب اتنين electrons في orbital واحد، والاتنين spin لفوق… ينفع؟ فكّروا. <long pause>","screen_text":"Two electrons in one orbital, both ↑↑: allowed?"},{"id":"l8","visual":"Answer: on cue l8 'لأ' the question leaves the band and a YK.wrongMark (90) flashes on the ↑↑ box for 0.6 s; on cue 'opposite' the right arrow flips to ↓ (rotate 180 deg over 0.4 s, cyan -> pink), then ONE YK.rightMark next to label 'No: Pauli needs opposite spins (↑↓)' (52) at y 1400.","tts_text":"لأ، Pauli بيقول opposite spins… لازم واحد يقلب لتحت.","screen_text":"No: Pauli needs opposite spins (↑↓)"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Electron spin and the Pauli principle', line:'One orbital: max 2 electrons, opposite spins.', formula:'↑↓', t, pulse:[{word:'2', at:YK.cue('l9','اتنين')}, {word:'opposite', at:YK.cue('l9','opposite')}, {word:'spins', at:YK.cue('l9','spins')}]}) from cue l9 start, held through the line + tail (>= 2.5 s). Loop (S5): last 0.8 s returns to the frame-0 ↑↓ box, arrows bobbing.","tts_text":"الـ orbital: اتنين بالكتير، و opposite spins كمان.","screen_text":"One orbital: max 2 electrons, opposite spins."}],"logline":"Each electron spins and acts like a tiny magnet; one orbital holds at most two electrons with opposite spins (↑↓), so their magnetic effects cancel, while an unpaired electron's effect 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في الـ orbital الواحد سهم لفوق وسهم\nلتحت\nكل electron بيعمل spin حوالين نفسه فبيبقى\nزي magnet صغير\nوالـ spin ليه اتجاهين بس سهم لفوق أو لتحت\nالـ Pauli principle الـ orbital ياخد اتنين\nبالكتير والـ spins opposite لبعض\nاتنين magnets صغيرين عكس بعض فالـ magnetic\neffects بتلغي بعض\nبس الـ electron اللي لوحده unpaired تأثيره\nبيفضل\nطب اتنين electrons في orbital واحد\nوالاتنين spin لفوق ينفع فكّروا\nلأ Pauli بيقول opposite spins لازم واحد\nيقلب لتحت\nالـ orbital اتنين بالكتير و opposite spins\nكمان","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":15},{"id":"chem-s3-en.video-short-atom.electron-configuration-writing","kind":"short","version":1,"ord":23,"content_lang":"ar-EG","primary_concept_id":"atom.electron-configuration-writing","concepts":[{"concept_id":"atom.electron-configuration-writing","role":"primary"}],"title":"Writing electronic configurations","payload":{"title":"Writing electronic 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A shortcut?' (~96, Cairo 1000, mono digits). A long empty writing line (rounded bar, 864 px, x 108-972) at y 1500. Signals: electrons flash on cue l1 'electron'; the writing line pulses on 'سطر'. Label 'calcium' (48) under the atom on cue 'calcium'.","tts_text":"الـ calcium عنده عشرين electron… نكتبهم في سطر قصير إزاي؟","screen_text":"₂₀Ca: 20 electrons. A shortcut?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Aufbau principle (order of filling)', {kind:'prereq', align:'center'}) for <= 2 s from line start. Hook exits; atom slides up to y 820 and dims to 35%. Two capacity tiles at y 1150: s = YK.electronBoxes(ctx, 300, 1150, {boxes:1, size:130, electrons:2, fill: prog from cue 'اتنين' over 0.5 s, label:'s holds 2'}) entering at line start; p = YK.electronBoxes(ctx, 700, 1150, {boxes:3, size:130, electrons:6, fill: prog from cue 'ستة' over 0.8 s, label:'p holds 6'}) entering on cue word index 8 ('p'; single-letter needle unreliable). Labels 48 (kit default). No energy axis (G43).","tts_text":"بنملا بالترتيب: الـ s sublevel ياخد اتنين، والـ p sublevel ستة.","screen_text":"Fill in order: s holds 2, p holds 6"},{"id":"l3","visual":"Tiles exit. '_{20}Ca' tag (YK.label mono 56) at the left of the band; the full configuration types itself left -> right on the writing line at y 1150: YK.formula('1s^2 2s^2 2p^6 3s^2 3p^6 4s^2', mono, size 64, shrink with YK.formula.measure to fit 864, never < 52); reveal from cue l3 'one' to cue 'four', '4s^2' lands on 'two'. Linked model: the dimmed atom above highlights the matching shell as each part types (highlightShell 0 for 1s², 1 for 2s² 2p⁶, 2 for 3s² 3p⁶, 3 for 4s²; correct for Ca, no 3d). On cue 'طويل' a coral two-headed measuring arrow spans the line.","tts_text":"نبدأ من one s، ولحد four s two… سطر طويل.","screen_text":"₂₀Ca: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²"},{"id":"l4","visual":"Aha part 1: on cue l4 'تمنتاشر' the part '1s^2 2s^2 2p^6 3s^2 3p^6' turns gold and a running total counts 2 -> 4 -> 10 -> 12 -> 18 above it (YK.counter value drawn with YK.label mono 56, not YK.text: Cairo's open '4'). On cue 'argon' label 'First 18 electrons = [Ar], the noble gas before' (52, <= 2 lines) at y 1380 (no separate '₁₈Ar' tag, G16).","tts_text":"أول تمنتاشر electron دول بالظبط الـ argon، الـ noble gas اللي قبله.","screen_text":"First 18 electrons = [Ar], the noble gas before"},{"id":"l5","visual":"Aha part 2 (hold >= 1.5 s), answers the hook. Cue order follows the voice: term 'Short form' (Cairo 1000, 80) in the band on cue l5 'short'; atom pulses on 'calcium'; on 'argon' the gold part collapses into one chip '[Ar]' (mono 72, gold); on 'four' the line becomes YK.formula('_{20}Ca: [Ar] 4s^2', mono 80) centred at y 1150, short (the measuring arrow shrinks with it).","tts_text":"الـ short form بتاع الـ calcium: argon بين قوسين، وبعده four s two بس.","screen_text":"Short form: ₂₀Ca: [Ar] 4s²"},{"id":"l6","style":"curious","visual":"Self-check on a new case (R8: Na and neon not shown so far): YK.atom(ctx, 540, 900, {Z:11, size:240}) (2,8,1); an empty writing line at y 1250 with one blank chip '[ ? ]' and a '?' after it. Question '₁₁Na: write the short form.' (Cairo 900, 72; YK.label for the subscript) in the band on cue l6 'sodium'. YK.checkPause(ctx, 540, 1540, {t, start: YK.cue('l6','فكّروا'), dur: YK.cue('l7') - that start, question:'', answer:''}) through the stitched silence (the trailing <long pause> is stripped; pause_after_s default 1.5 s, so the ring runs >= 1.5 s); ring exits at cue l7 + 0.5 s.","tts_text":"طب الـ sodium، حداشر electron. الـ short form بتاعه إيه؟ فكّروا. <long pause>","screen_text":"₁₁Na: write the short form."},{"id":"l7","visual":"Answer: on cue l7 'neon' the blank chip fills '[Ne]' (gold) and the question leaves the band; on cue 'three' '3s^1' types after it: YK.formula('_{11}Na: [Ne] 3s^1', mono 80) at y 1250; on cue 'عشرة' the check tag '10 + 1 = 11' (YK.label mono 56) under it + ONE YK.rightMark at its left.","tts_text":"neon بين قوسين، وبعده three s one… عشرة وواحد، حداشر.","screen_text":"[Ne] 3s¹  (10 + 1 = 11)"},{"id":"l8","visual":"Voiced lock-in (S3): YK.takeaway({title:'Writing electronic configurations', line:'Short form: [noble gas before it] + the rest.', formula:'_{20}Ca: [Ar] 4s^2', t, pulse:[{word:'noble', at:YK.cue('l8','noble')}, {word:'gas', at:YK.cue('l8','gas')}, {word:'rest', at:YK.cue('l8','الباقي')}]}) from cue l8 start, held through the line + tail (>= 2.5 s). Loop (S5): last 0.8 s returns to the frame-0 calcium atom with '[Ar] 4s²' written short on the line.","tts_text":"الـ short form: noble gas قبله، وبعده الباقي.","screen_text":"Short form: [noble gas before it] + the rest."}],"logline":"Write a configuration by filling sublevels in order (s takes 2, p takes 6); the first 18 electrons of calcium are argon's, so ₂₀Ca is written [Ar] 4s², the short form Chapter 1 starts 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calcium عنده عشرين electron نكتبهم في\nسطر قصير إزاي\nبنملا بالترتيب الـ s sublevel ياخد اتنين\nوالـ p sublevel ستة\nنبدأ من one s ولحد four s two سطر طويل\nأول تمنتاشر electron دول بالظبط الـ argon\nالـ noble gas اللي قبله\nالـ short form بتاع الـ calcium argon بين\nقوسين وبعده four s two بس\nطب الـ sodium حداشر electron الـ short\nform بتاعه إيه فكّروا\nneon بين قوسين وبعده three s one عشرة\nوواحد حداشر\nالـ short form noble gas قبله وبعده الباقي","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":16},{"id":"chem-s3-en.video-short-pt.blocks","kind":"short","version":1,"ord":25,"content_lang":"ar-EG","primary_concept_id":"pt.blocks","concepts":[{"concept_id":"pt.blocks","role":"primary"}],"title":"Blocks of the periodic table","payload":{"title":"Blocks of the periodic table","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): schematic long-form table silhouette (NOT the cell table, S10), YK.roundRect regions in kit block colours at x 108-972, y 760-1240: s (2 columns, left, pink), d (10 columns, middle, violet), p (6 columns, right, cyan), f (2 rows below, y 1300-1400, amber), breathing gently (alpha sine). Two pop-out tiles (140 px, symbol Cairo 1000 64) floating above their period-3 cells with thin leaders: 'Na' over the s region, 'Cl' over the p region, a dashed line joining them along the row. Hook on screen at t=0 in the band (Cairo 1000 ~110): 'Same period. Different blocks?'. Signals: Na flashes on cue l1 'sodium', Cl on 'chlorine', the row line on 'period'; tile labels 'sodium' / 'chlorine' (48) under the tiles on their cues.","tts_text":"الـ sodium والـ chlorine في نفس الـ period… وفي blocks مختلفة؟","screen_text":"Same period. Different blocks?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Writing electronic configurations', {kind:'prereq', align:'center'}) for <= 2 s. Hook exits; silhouette dims to 35% and slides down to y 1180-1600. On cue l2 'electron' one cyan electron drops into a generic sublevel box (YK.electronBoxes boxes:1, size 160, labelPos 'none') at (540, 900) with a '?' tag; the tag pulses on 'sublevel'. On cue 'block' headline 'Block = the sublevel that receives the last electron' (Cairo 900, 64, <= 2 lines) in the band.","tts_text":"آخر electron دخل أنهي sublevel؟ ده بيحدد الـ block بتاعه.","screen_text":"Block = the sublevel that receives the last electron"},{"id":"l3","visual":"YK.formula('_{11}Na: [Ne] 3s^1', mono 72) at y 900, '3s^1' accents gold on cue l3 'three'; on cue 's-block' an arrow from '3s^1' down to the s region (now 100%, left), which lights; the Na tile pops into it; label 's-block' (52) beside the region. Headline from l2 leaves on cue 'sodium'.","tts_text":"الـ sodium آخره three s one، فهو s-block، على الشمال.","screen_text":"₁₁Na: …3s¹ → s-block"},{"id":"l4","visual":"YK.formula('_{17}Cl: [Ne] 3s^2 3p^5', mono 72) replaces Na's at y 900, '3p^5' accents gold on cue l4 'three'; on cue 'p-block' an arrow to the p region (right), which lights; the Cl tile pops in there; label 'p-block' (52). Answers the hook: same row, different last sublevel.","tts_text":"والـ chlorine آخره three p five، p-block، على اليمين.","screen_text":"₁₇Cl: …3p⁵ → p-block"},{"id":"l5","visual":"Aha (hold >= 1.5 s): full silhouette at 100% (y 760-1400). d region lights + label 'd-block' (52) on cue l5 'd-block'; f rows light + label 'f-block' (52) on cue 'f-block'. No column-count ticks (not voiced, G16).","tts_text":"وبينهم في النص الـ d-block، والـ f-block صفين تحت.","screen_text":"d-block: the middle · f-block: two rows below"},{"id":"l6","visual":"d and f regions dim to 35%. On cue l6 's-block' the s region and the p region except its last column glow gold together under one bracket label 'Representative elements (IA–VIIA)' (48); on cue 'noble' the last p column (group 0) glows in its own colour with label 'Noble gases (0)' (48): noble gases sit OUTSIDE the representative bracket (lesson pt.blocks).","tts_text":"الـ s-block والـ p-block: representative elements، والـ noble gases لوحدهم.","screen_text":"s- and p-blocks: representative elements (IA–VIIA) + noble gases (0)"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8: Ti not shown so far): YK.formula('_{22}Ti: [Ar] 4s^2 3d^2', mono 72) at y 820; silhouette at 60% at y 1000-1300, all regions neutral grey. Question '₂₂Ti: [Ar] 4s² 3d². Which block?' (Cairo 900, 72; YK.label for notation) in the band on cue l7 'titanium'. YK.checkPause(ctx, 540, 1540, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (the trailing <long pause> is stripped; pause_after_s default 1.5 s, so the ring runs >= 1.5 s); ring exits at cue l8 + 0.5 s.","tts_text":"titanium: argon، four s two، three d two. أنهي block؟ فكّروا. <long pause>","screen_text":"₂₂Ti: [Ar] 4s² 3d². Which block?"},{"id":"l8","visual":"Answer: on cue l8 'd-block' the d region lights violet and the question leaves the band; on cue 'three' '3d^2' accents gold in the formula with an arrow to the d region; label 'd-block: the last electron enters 3d' (52) at y 1400 + ONE YK.rightMark.","tts_text":"d-block: آخر electron راح three d، في النص.","screen_text":"d-block: the last electron enters 3d"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Blocks of the periodic table', line:'The block = the sublevel of the last electron.', t, pulse:[{word:'sublevel', at:YK.cue('l9','sublevel')}, {word:'last', at:YK.cue('l9','electron')}, {word:'electron', at:YK.cue('l9','electron')}]}) from cue l9 start, held through the line + tail (>= 2.5 s). Loop (S5): last 0.8 s returns to the frame-0 silhouette with the Na and Cl tiles, each now in its lit block.","tts_text":"sublevel آخر electron بيحدد الـ block بتاعه.","screen_text":"The block = the sublevel of the last electron."}],"logline":"The block is the sublevel that receives the last electron: sodium (…3s¹) is s-block, chlorine (…3p⁵) p-block; s and p hold the representative elements and the noble gases, the d-block sits between them and the f-block 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sodium والـ chlorine في نفس الـ period\nوفي blocks مختلفة\nآخر electron دخل أنهي sublevel ده بيحدد\nالـ block بتاعه\nالـ sodium آخره three s one فهو s-block\nعلى الشمال\nوالـ chlorine آخره three p five p-block\nعلى اليمين\nوبينهم في النص الـ d-block والـ f-block\nصفين تحت\nالـ s-block والـ p-block representative\nelements والـ noble gases لوحدهم\ntitanium argon four s two three d two أنهي\nblock فكّروا\nd-block آخر electron راح three d في النص\nsublevel آخر electron بيحدد الـ block\nبتاعه","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":17},{"id":"chem-s3-en.video-short-te.position-in-periodic-table","kind":"short","version":1,"ord":27,"content_lang":"ar-EG","primary_concept_id":"te.position-in-periodic-table","concepts":[{"concept_id":"te.position-in-periodic-table","role":"primary"}],"title":"Transition elements in the periodic table","payload":{"title":"Transition elements in the periodic table","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): two YK.elementCard at w 380 (>= 380 keeps all card text >= 40 px): {sym:'Fe', nameEn:'iron', config:'', group:''} at (320, 1050) and {sym:'Cu', nameEn:'copper', config:'', group:''} at (760, 1050), floating +-10 px (sine), inside a dotted frame + hook on screen at t=0 in the band (Cairo 1000 ~100): 'Transition elements: just a few metals?'. Signals: Fe hl on cue l1 'iron', Cu on 'copper'; the dotted frame tightens on 'شوية'.","tts_text":"الـ transition elements، زي الـ iron والـ copper… شوية metals وبس؟","screen_text":"Transition elements: just a few metals?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Blocks of the periodic table', {kind:'prereq', align:'center'}) for <= 2 s. Hook exits; the cards shrink into their cells of YK.periodicTable(ctx, 108, 720, 864, {showSymbols:false, showNumbers:false, labels:false, highlight, hp}) (a block-colour map: no 17 px cell text). On cue l2 's-block' highlight {blocks:['s']}, on 'p-block' {blocks:['p']}; on cue 'نص' {blocks:['d','f']} while s and p dim (hp tween). Label 'Between the (s) and (p) blocks' (52, book wording) at y 1300.","tts_text":"مكانهم في نص الجدول، بين الـ s-block والـ p-block بالظبط.","screen_text":"Between the (s) and (p) blocks"},{"id":"l3","visual":"Myth beat (top concept misconception, R11, G40): small wrong picture (60%, y 900-1200, coral): just two small tiles 'Fe' 'Cu' in a box, label 'A few famous metals' (48, coral) on cue l3 'metals'; YK.wrongMark on cue 'غلط'; exits 0.4 s later.","tts_text":"ناس فاكرينهم شوية metals… غلط خالص.","screen_text":"A few famous metals ✕"},{"id":"l4","visual":"Right version, bigger and longer: the same block map (y 720-1180) with d and f cells lighting in Z order as a counter runs 0 -> 60 (YK.counter drawn with YK.label mono 96 gold at y 1300, suffix '+'; YK.label not YK.text: Cairo's open '4') from cue l4 'ستين' over 1.5 s (highlight.Z grows with the counter). On cue 'نص' a half-bar (YK.roundRect 864 x 40 at y 1440, midline marked, transition fill passing 50%) + label 'More than half the known elements' (48) at y 1530 + YK.rightMark.","tts_text":"أكتر من ستين element، يعني أكتر من نص العناصر المعروفة.","screen_text":"More than 60 elements: more than half the known elements ✓"},{"id":"l5","visual":"Block map at 100% (y 720-1180), symbols off. On cue l5 'main' highlight {blocks:['d']} (violet, kit d colour) and f rows dim; label 'Main transition elements' (48, violet) in the empty area above the d-block (rows 1-3); on cue 'd-block' tag 'd-block' (52) under the table at y 1260; on cue 'هندرسهم' a small tag 'studied in this chapter' (44) pins onto the d-block.","tts_text":"النوع الأول main transition elements في الـ d-block، ودول اللي هندرسهم.","screen_text":"Main transition elements: d-block (studied in this chapter)"},{"id":"l6","visual":"On cue l6 'inner' the two f rows glow amber (kit f colour) with label 'Inner transition elements' (48, amber) under them; the d-block stays lit at 60% with its 'studied in this chapter' tag; on cue 'f-block' tag 'f-block' (52) and a short arrow from the f rows to the dashed group-3 placeholders (57–71, 89–103) in periods 6 and 7, where they belong.","tts_text":"والتاني inner transition elements، في الـ f-block، الصفين اللي تحت.","screen_text":"Inner transition elements: f-block (two rows below)"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8: Pu not shown so far; targets the second misconception): neutral grey block map (y 720-1180, symbols off) with Pu's cell lit; a pop-out tile 'Pu' (140 px, Cairo 1000 64) above it with a leader. Two choice chips 'Main' / 'Inner' (Cairo 800 52, roundRect) at y 1300. Question 'Pu sits in the two bottom rows. Main or inner?' (Cairo 900, 72, <= 2 lines) in the band on cue l7 'plutonium'. YK.checkPause(ctx, 540, 1540, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (the trailing <long pause> is stripped; pause_after_s default 1.5 s, so the ring runs >= 1.5 s); ring exits at cue l8 + 0.5 s.","tts_text":"طب الـ plutonium، في الصفين اللي تحت… main ولا inner؟ فكّروا. <long pause>","screen_text":"Pu sits in the two bottom rows. Main or inner?"},{"id":"l8","visual":"Answer: on cue l8 'inner' the 'Inner' chip lights amber + ONE YK.rightMark, question leaves the band; on cue 'f-block' the f rows glow amber with tag 'f-block' (52); on 'هندرسهم' the 'studied in this chapter' tag flashes on the d-block only (Pu is not in it).","tts_text":"inner، لأنه في الـ f-block… مش من اللي هندرسهم.","screen_text":"Inner transition element (f-block)"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Transition elements in the periodic table', line:'Between the (s) and (p) blocks: more than 60.', formula:'main (d) + inner (f)', t, pulse:[{word:'more', at:YK.cue('l9','أكتر')}, {word:'60', at:YK.cue('l9','ستين')}]}) from cue l9 start, held through the line + tail (>= 2.5 s). Loop (S5): last 0.8 s returns to the frame-0 Fe and Cu cards, now with a violet d-block strip behind them.","tts_text":"بين الـ s-block والـ p-block: أكتر من ستين.","screen_text":"Between the (s) and (p) blocks: more than 60."}],"logline":"Transition elements are not a few famous metals: they fill the middle of the table between the s- and p-blocks, more than 60 elements, split into main (d-block, studied in this chapter) and inner (f-block) transition 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transition elements زي الـ iron والـ\ncopper شوية metals وبس\nمكانهم في نص الجدول بين الـ s-block والـ\np-block بالظبط\nناس فاكرينهم شوية metals غلط خالص\nأكتر من ستين element يعني أكتر من نص\nالعناصر المعروفة\nالنوع الأول main transition elements في\nالـ d-block ودول اللي هندرسهم\nوالتاني inner transition elements في الـ\nf-block الصفين اللي تحت\nطب الـ plutonium في الصفين اللي تحت main\nولا inner فكّروا\ninner لأنه في الـ f-block مش من اللي\nهندرسهم\nبين الـ s-block والـ p-block أكتر من ستين","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":18},{"id":"chem-s3-en.video-short-te.d-block-groups","kind":"short","version":1,"ord":29,"content_lang":"ar-EG","primary_concept_id":"te.d-block-groups","concepts":[{"concept_id":"te.d-block-groups","role":"primary"}],"title":"Main transition elements (d-block)","payload":{"title":"Main transition elements (d-block)","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13), custom (not dBlockZoom: its 1-row strip gives 21 px labels in 9:16): ten tall column bars (72 px wide, pitch 86, x 112-972, y 760-1360, violet 30% fill, kit d colour) and the eight book labels IIIB IVB VB VIB VIIB VIII IB IIB (JetBrains Mono 44, one row at y 650, spaced across 864 px) jiggling (YK.rng-seeded +-6 px) as if they do not fit + hook on screen at t=0 in the band (Cairo 1000 ~110): '8 group labels. 10 columns?'. Signals: labels flash on cue l1 'labels'; column bars flash left -> right on 'columns' (YK.stagger).","tts_text":"الـ d-block فيه تمن group labels بس… وعشر columns! إزاي؟","screen_text":"8 group labels. 10 columns?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Energy sublevels (s, p, d, f)', {kind:'prereq', align:'center'}) for <= 2 s. A 5-box d strip YK.electronBoxes(ctx, 540, 1540, {boxes:5, size:150, electrons:10, fill: prog from cue 'عشرة' to cue 'columns', label:'d', labelPos:'left'}); as each electron lands, one column bar lights left -> right (electron k ↔ column k), ending with a '10' count (YK.label mono 64) over the bars. Headline 'd holds up to 10 electrons → 10 columns' (Cairo 900, 64) in the band on cue 'columns'. No per-column d¹…d¹⁰ tags and no Cr/Cu note (Cu sits in column 11 with 3d¹⁰: a per-column d-count tag would be false; G16).","tts_text":"الـ d sublevel بياخد لحد عشرة electrons، عشان كده الـ columns عشرة.","screen_text":"d holds up to 10 electrons → 10 columns"},{"id":"l3","visual":"Myth beat (top concept misconception, R11, G40): small wrong picture (60%, y 900-1250, coral): the 8 labels over 8 equal columns, 'VIII' over a single column and two leftover columns with '?' tags; label 'Group VIII = 1 column' (48, coral) on cue l3 'column'; YK.wrongMark on cue 'غلط'; exits 0.4 s later.","tts_text":"ناس فاكرة group تمانية column واحد… غلط.","screen_text":"Group VIII = 1 column ✕"},{"id":"l4","visual":"Aha (hold >= 1.5 s), answers the hook: back to the 10 column bars. On cue l4 'تمانية' 'VIII' stretches over columns 8-10 (gold bracket) with one label '(8) (9) (10)' (YK.label mono 44) centred under the three bars; on cue 'labels' all eight labels settle onto the ten columns left -> right in book order (YK.GROUPS_BOOK slice 2..11), drawn rotated -90 deg (reading upward, mono 44) because a 72 px column cannot hold 'VIIB' at >= 40 px. Label 'Group VIII: three columns' (52) at y 1480 + YK.rightMark.","tts_text":"group تمانية تلات columns، فالتمن labels بيغطوا العشرة.","screen_text":"Group VIII: three columns (8), (9), (10)"},{"id":"l5","visual":"Zoom into group VIII (YK.camera 0.8 s): 3 x 2 grid of custom tiles (220 px, symbol Cairo 1000 96, name 44): row 1 (period 4) Fe 'iron', Co 'cobalt', Ni 'nickel' at y 950; row 2 (period 5) three blank grey tiles (no symbols), dimmed, tag 'below' (44) at y 1220. Each row-1 tile lights on its spoken cue ('iron', 'cobalt', 'nickel'); on cue 'similar' a gold horizontal band links Fe-Co-Ni while a thin grey vertical link to the tiles below stays faint; label 'Similar horizontally' (52) at y 1450.","tts_text":"الـ iron والـ cobalt والـ nickel similar horizontally، أكتر من اللي تحتهم.","screen_text":"Fe, Co, Ni: similar horizontally more than the elements below"},{"id":"l6","style":"curious","visual":"Self-check on a new case (R8: V and the VB d-count not shown so far): one 5-box 3d strip YK.electronBoxes(ctx, 540, 960, {boxes:5, electrons:0, size:150, label:'3d', labelPos:'left'}) with a '?' over it; a column ruler at y 1220 with only '(3) IIIB = d¹' labelled (YK.label mono 48) and (4), (5) as empty slots. Question '₂₃V is in group (5) VB. How many 3d electrons?' (Cairo 900, 72, <= 2 lines) in the band on cue l6 'vanadium'. YK.checkPause(ctx, 540, 1540, {t, start: YK.cue('l6','فكّروا'), dur: YK.cue('l7') - that start, question:'', answer:''}) through the stitched silence (the trailing <long pause> is stripped; pause_after_s default 1.5 s, so the ring runs >= 1.5 s); ring exits at cue l7 + 0.5 s.","tts_text":"الـ vanadium في group خمسة: كام electron في three d؟ فكّروا. <long pause>","screen_text":"₂₃V is in group (5) VB. How many 3d electrons?"},{"id":"l7","visual":"Answer (cue order follows the voice): on cue l7 word 0 ('تلاتة') a big '3' (YK.label mono 96, gold) replaces the '?' and the question leaves the band; on cue 'واحد' the ruler counts (3) d¹ → (4) d² → (5) d³ (YK.stagger); on cue 'vanadium' the strip fills 3 single ↑ (Hund, no pairing) and YK.formula('_{23}V: [Ar] 4s^2 3d^3', mono 64) appears at y 1480 + ONE YK.rightMark.","tts_text":"تلاتة: group تلاتة فيه واحد، فالـ vanadium فيه تلاتة.","screen_text":"3 electrons: ₂₃V: [Ar] 4s² 3d³"},{"id":"l8","visual":"Voiced lock-in (S3): YK.takeaway({title:'Main transition elements (d-block)', line:'The d sublevel takes up to 10 electrons → 10 columns.', formula:'VIII = (8) (9) (10)', t, pulse:[{word:'columns', at:YK.cue('l8','columns')}, {word:'10', at:YK.cue('l8','عشرة')}]}) from cue l8 start, held through the line + tail (>= 2.5 s). Loop (S5): last 0.8 s returns to the frame-0 ten bars with the eight labels settled (VIII over three).","tts_text":"عشر columns، عشان الـ d sublevel بياخد عشرة.","screen_text":"The d sublevel takes up to 10 electrons → 10 columns."}],"logline":"The d sublevel takes up to 10 electrons, so the d-block has ten columns but only eight group labels: group VIII alone spans three columns (8, 9, 10), whose elements are similar horizontally more than down the 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d-block فيه تمن group labels بس وعشر\ncolumns إزاي\nالـ d sublevel بياخد لحد عشرة electrons\nعشان كده الـ columns عشرة\nناس فاكرة group تمانية column واحد غلط\ngroup تمانية تلات columns فالتمن labels\nبيغطوا العشرة\nالـ iron والـ cobalt والـ nickel similar\nhorizontally أكتر من اللي تحتهم\nالـ vanadium في group خمسة كام electron في\nthree d فكّروا\nتلاتة group تلاتة فيه واحد فالـ vanadium\nفيه تلاتة\nعشر columns عشان الـ d sublevel بياخد عشرة","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":19},{"id":"chem-s3-en.video-short-te.transition-series","kind":"short","version":1,"ord":31,"content_lang":"ar-EG","primary_concept_id":"te.transition-series","concepts":[{"concept_id":"te.transition-series","role":"primary"}],"title":"The four transition series","payload":{"title":"The four transition series","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13), top -> bottom: YK.elementCard({sym:'Fe', nameEn:'iron', config:'', group:'', w:380}) at (620, 800) pulsing; tag 'Period 4' (YK.label 52) at its left (x 120-330, y 800); a 5-box strip YK.electronBoxes(ctx, 540, 1250, {boxes:5, size:110, label:'3d', labelPos:'left', electrons:6, fill: looping 0 -> 1 every 3 s, deterministic from t}); a ghost strip '4d?' (same size, 40% alpha, coral rim) at y 1420. Hook on screen at t=0 in the band (Cairo 1000 ~110): 'Period 4 → 3d. Why not 4d?'. Signals: 'Period 4' flashes on cue l1 'period', the 3d strip on 'three', the ghost on 'four'.","tts_text":"الـ iron في period أربعة، بيملا three d… مش four d ليه؟","screen_text":"Period 4 → 3d. Why not 4d?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'Main transition elements (d-block)', {kind:'prereq', align:'center'}) for <= 2 s (the short's only chip). Card and strips exit. YK.periodicTable(ctx, 108, 720, 864, {showSymbols:false, showNumbers:false, labels:false, highlight:{blocks:['d']}}) as a block map; on cue l2 'series' a gold outline sweeps left -> right along the period-4 d row (same look as the dBlockZoom series overlay, drawn by the page so only row 1 shows) and Fe's cell glows; label 'Transition series: one d sublevel fills' (52) at y 1300 on cue 'sublevel'.","tts_text":"الـ transition series صف في الـ d-block، بيتملي فيه d sublevel واحد.","screen_text":"Transition series: a row where one d sublevel fills"},{"id":"l3","visual":"Myth beat (top concept misconception, R11, G40): small wrong tag (60%, coral) on the outlined row: 'Period 4 → 4d' (YK.formula mono 56) with label 'same number as the period' (44, coral) on cue l3 'four'; YK.wrongMark on cue 'غلط'; exits 0.4 s later.","tts_text":"ناس بتقول period أربعة يبقى four d… غلط.","screen_text":"Period 4 → 4d ✕"},{"id":"l4","visual":"Aha (hold >= 1.5 s), answers the hook. No second chip (G16). YK.flow({layout:'col', area:{x:380, y:700, w:320, h:700}, nodes:['3p','4s','3d','4p'], edges: 3p→4s→3d→4p}) = the filling order, top -> bottom. On cue l4 'three' the 3d node lights violet; on cue 'four' the 4s node lights pink and the 4s → 3d edge goes gold; on cue 'period' a gold bracket 'Period 4' (52) groups the 4s, 3d and 4p nodes (book p.4: the first series comes after calcium). Label '3d fills after 4s → in period 4' (52) at y 1500 + YK.rightMark. No energy axis, no 'lower in energy' (G43).","tts_text":"الـ three d بييجي بعد الـ four s، فبيتملي في period أربعة.","screen_text":"3d fills after 4s → in period 4"},{"id":"l5","visual":"Four stacked d rows (custom: 10 symbol-free violet bars 48 px wide, pitch 51, x 108-618) at y 760 / 900 / 1040 / 1180, each with a tag at x 650 (YK.label 44, left-aligned): '3d · period 4' on cue l5 'three', '4d · period 5' and '5d · period 6' staggered in between, '6d · period 7' on cue 'six'; the period numbers in the tags pulse gold on cue 'periods' / 'سبعة'. No 'period n → (n−1)d' bracket here (it is voiced only in l8 and would answer the l6 check).","tts_text":"الأربع series: من three d لحد six d، في periods أربعة لحد سبعة.","screen_text":"Four series: 3d → 6d, periods 4 → 7"},{"id":"l6","style":"curious","visual":"Self-check on a new case (R8: Hg not shown so far): YK.elementCard({sym:'Hg', nameEn:'mercury', config:'', group:'', w:380}) at (620, 800) with tag 'Period 6' (52) at its left; an empty strip YK.electronBoxes(ctx, 540, 1250, {boxes:5, size:110, electrons:0, label:'?d', labelPos:'left'}). Question '₈₀Hg is in period 6. Which d sublevel fills?' (Cairo 900, 72, <= 2 lines) in the band on cue l6 'mercury'. YK.checkPause(ctx, 540, 1540, {t, start: YK.cue('l6','فكّروا'), dur: YK.cue('l7') - that start, question:'', answer:''}) through the stitched silence (the trailing <long pause> is stripped; pause_after_s default 1.5 s, so the ring runs >= 1.5 s); ring exits at cue l7 + 0.5 s.","tts_text":"طب الـ mercury، في period ستة. بيملا أنهي d sublevel؟ فكّروا. <long pause>","screen_text":"₈₀Hg is in period 6. Which d sublevel fills?"},{"id":"l7","visual":"Answer: on cue l7 'five' the strip label '?d' resolves to '5d' and the question leaves the band; on cue 'ناقص' YK.formula('(6 − 1)d = !{5d}', mono 64) at y 1420 + ONE YK.rightMark; on cue 'third' card and strip slide up and fade, the formula holds, and the third row of the l5 stack returns alone at y 1560 with tag 'Third series: ends with ₈₀Hg' (YK.label 48), its last bar gold (book p.4: Hg 6s² 4f¹⁴ 5d¹⁰).","tts_text":"five d، ستة ناقص واحد… الـ third series، والـ mercury آخرها.","screen_text":"5d: (6 − 1)d → third series (Hg is its last element)"},{"id":"l8","visual":"Voiced lock-in (S3): YK.takeaway({title:'The four transition series', line:'Period n fills the (n − 1)d sublevel.', formula:'period n → (n − 1)d', t, pulse:[{word:'(n', at:YK.cue('l8','بواحد')}, {word:'1)d', at:YK.cue('l8','بواحد')}]}) from cue l8 start, held through the line + tail (>= 2.5 s). Loop (S5): last 0.8 s returns to the frame-0 Fe card + 3d strip, the ghost '4d?' gone.","tts_text":"الـ d sublevel أقل من الـ period بواحد.","screen_text":"Period n fills the (n − 1)d sublevel."}],"logline":"Each transition series is a row of the d-block where one d sublevel fills; 3d fills after 4s, so it fills in period 4: in period n the (n−1)d sublevel fills, from 3d (period 4) to 6d (period 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iron في period أربعة بيملا three d مش\nfour d ليه\nالـ transition series صف في الـ d-block\nبيتملي فيه d sublevel واحد\nناس بتقول period أربعة يبقى four d غلط\nالـ three d بييجي بعد الـ four s فبيتملي\nفي period أربعة\nالأربع series من three d لحد six d في\nperiods أربعة لحد سبعة\nطب الـ mercury في period ستة بيملا أنهي d\nsublevel فكّروا\nfive d ستة ناقص واحد الـ third series والـ\nmercury آخرها\nالـ d sublevel أقل من الـ period بواحد","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":20},{"id":"chem-s3-en.video-short-te.first-series-elements","kind":"short","version":1,"ord":33,"content_lang":"ar-EG","primary_concept_id":"te.first-series-elements","concepts":[{"concept_id":"te.first-series-elements","role":"primary"}],"title":"Elements of the first transition series","payload":{"title":"Elements of the first transition series","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): a crust pie (custom: circle r 260 at (540, 860), earth-brown, slowly rotating) with a 7% wedge (25 deg) in gold pulsing and '7%' (YK.label mono 72, gold) beside it; below it the series strip (custom tiles, see l2) at 50% alpha. Hook on screen at t=0 in the band (Cairo 1000 ~110): 'Nearly 7%. Yet so important?'. Signals: the strip flashes to 100% on cue l1 'metals', the wedge on 'سبعة'.","tts_text":"عشر metals، مع بعض سبعة في المية بس… ومهمين ليه؟","screen_text":"Nearly 7%. Yet so important?"},{"id":"l2","visual":"Prereq chip YK.chip(ctx, 540, 600, 'The four transition series', {kind:'prereq', align:'center'}) for <= 2 s. Pie exits. Series strip, custom (not dBlockZoom: its tiles always print Z at 29 px and cannot hide symbols for the l7 check): 2 rows x 5 tiles (160 px, pitch 172; row 1 Sc Ti V Cr Mn at y 1000, row 2 Fe Co Ni Cu Zn at y 1240), violet, symbol Cairo 1000 72, no Z by default. On cue l2 'scandium' Sc glows + YK.label 'Z = 21' (mono 44) under it; tiles light in order (YK.stagger) to Zn on cue 'zinc' + 'Z = 30'. Headline in the band = screen_text, drawn with YK.label: 'First transition series: _{21}Sc → _{30}Zn' (Cairo 900, 64). Symbols only: the strip is the series' diagram; only spoken elements get cues and name tags (decision on R7 risk).","tts_text":"الـ first transition series: من الـ scandium واحد وعشرين، لحد الـ zinc تلاتين.","screen_text":"First transition series: ₂₁Sc → ₃₀Zn"},{"id":"l3","visual":"Same strip, Z labels gone (so the l7 check stays a check). On cue l3 'chromium' Cr glows with name tag 'chromium' (44, textDim) and Mn with 'manganese' on 'manganese'; Mn tries to jump ahead and snaps back behind Cr (mint tick). Same for Co 'cobalt' / Ni 'nickel' on their cues. Label 'In order of atomic number: Cr before Mn, Co before Ni' (52, <= 2 lines) at y 1460 on cue 'خلّي'. (Second recorded misconception: swapping Cr/Mn, Co/Ni.)","tts_text":"الـ chromium قبل الـ manganese، والـ cobalt قبل الـ nickel… خلّي بالك.","screen_text":"In order of atomic number: Cr before Mn, Co before Ni"},{"id":"l4","visual":"Book table p.5 as YK.chart(ctx, 108, 760, 864, 700, {type:'bar', data:[{x:'Sc',y:0.0026},{x:'Ti',y:0.66},{x:'V',y:0.02},{x:'Cr',y:0.014},{x:'Mn',y:0.11},{x:'Fe',y:5},{x:'Co',y:0.003},{x:'Ni',y:0.0089},{x:'Cu',y:0.0068},{x:'Zn',y:0.0078}], grow: prog from cue 'crust' over 1.2 s, highlight:['Fe']}) with title '% wt in the earth's crust' (48) in the band on cue 'crust'. On cue l4 'iron' Fe's bar turns gold with '5' (YK.label mono 56) on top and name tag 'iron' (44); the others stay tiny and unlabelled (no Ti value: not voiced). Book values only.","tts_text":"في الـ earth's crust، الـ iron لوحده خمسة في المية.","screen_text":"% wt in the earth's crust: Fe 5 · most others far below 1"},{"id":"l5","visual":"Myth beat (top concept misconception, R11, G40): small wrong picture (60%, y 900-1250, coral): YK.balance tipping toward a big pile of ore (YK.ore) vs a small one; one label 'Abundant = important' (48, coral) on cue l5 'كتير' (no extra pan labels, G16); YK.wrongMark on cue 'غلط'; exits 0.4 s later.","tts_text":"ناس فاكرة إن المهم هو اللي كتير… غلط.","screen_text":"Abundant = important ✕"},{"id":"l6","visual":"Aha (hold >= 1.5 s), answers the hook: Sc's tiny bar (0.0026, the smallest) zooms up (YK.camera 0.8 s) into a big Sc tile (380 px, name 'scandium' 48) at (540, 980); on cue 'properties' YK.icon 'plane' pops at its left, on the 'uses' cue ('والاستخدامات', or 'uses' after the tts fix) YK.icon 'lamp' at its right (two icons only; uses detail belongs to the te-uses unit, no alloy wording). Label 'Importance: properties and uses, not amount' (52) at y 1420 + YK.rightMark.","tts_text":"الأهمية من الـ properties والـ uses، مش من الكمية.","screen_text":"Importance comes from properties and uses, not amount ✓"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8: Z = 27 never shown alone; targets the Co/Ni swap): the 10-tile strip again (y 1000 / 1240) with every symbol hidden behind '?' except Sc (+ 'Z = 21', YK.label mono 44); a gold pointer hovers between tiles 7 and 8. Question 'First series: which element has atomic number (Z) 27?' (Cairo 900, 72, <= 2 lines) in the band on cue l7 'atomic'. YK.checkPause(ctx, 540, 1540, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (the trailing <long pause> is stripped; pause_after_s default 1.5 s, so the ring runs >= 1.5 s); ring exits at cue l8 + 0.5 s.","tts_text":"أنهي عنصر الـ atomic number بتاعه سبعة وعشرين؟ فكّروا. <long pause>","screen_text":"First series: which element has atomic number (Z) 27?"},{"id":"l8","visual":"Answer: on cue l8 'cobalt' tile 7 flips to 'Co' + 'Z = 27' + name tag 'cobalt' (44) + ONE YK.rightMark, question leaves the band; on cue 'nickel' tile 8 flips to 'Ni' + 'Z = 28' + 'nickel'; the rest of the strip reveals left -> right (symbols only).","tts_text":"الـ cobalt، وبعده الـ nickel تمانية وعشرين… مش العكس.","screen_text":"₂₇Co: cobalt (then ₂₈Ni)"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Elements of the first transition series', line:'Nearly 7%, but high economic importance.', formula:'_{21}Sc → _{30}Zn', t, pulse:[{word:'7', at:YK.cue('l9','سبعة')}, {word:'economic', at:YK.cue('l9','economic')}, {word:'importance', at:YK.cue('l9','importance')}, {word:'high', at:YK.cue('l9','عالية')}]}) from cue l9 start, held through the line + tail (>= 2.5 s). Loop (S5): last 0.8 s returns to the frame-0 crust pie with the gold 7% wedge and the strip below.","tts_text":"سبعة في المية، بس ليهم economic importance عالية.","screen_text":"Nearly 7%, but high economic importance."}],"logline":"The first transition series is ten metals, ₂₁Sc to ₃₀Zn, in order of atomic number (Cr before Mn, Co before Ni); together nearly 7% of the earth's crust, iron alone 5%, yet all of high economic 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metals مع بعض سبعة في المية بس ومهمين\nليه\nالـ first transition series من الـ\nscandium واحد وعشرين لحد الـ zinc تلاتين\nالـ chromium قبل الـ manganese والـ cobalt\nقبل الـ nickel خلّي بالك\nفي الـ earth's crust الـ iron لوحده خمسة\nفي المية\nناس فاكرة إن المهم هو اللي كتير غلط\nالأهمية من الـ properties والـ uses مش من\nالكمية\nأنهي عنصر الـ atomic number بتاعه سبعة\nوعشرين فكّروا\nالـ cobalt وبعده الـ nickel تمانية وعشرين\nمش العكس\nسبعة في المية بس ليهم economic importance\nعالية","countable":true,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":21},{"id":"chem-s3-en.video-short-phys.waves-light","kind":"short","version":1,"ord":75,"content_lang":"ar-EG","primary_concept_id":"phys.waves-light","concepts":[{"concept_id":"phys.waves-light","role":"primary"}],"title":"Light and waves","payload":{"title":"Light and waves","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): two horizontal sine waves drawn with ctx paths (lineWidth 8), red (#f87171, wavelength 240 px) at y 820 and blue (#60a5fa, wavelength 144 px) at y 1120, both scrolling left → right at the SAME speed 720 px/s for the whole video (phase = t·720; this makes red exactly 3 and blue exactly 5 waves per second, so the l5 counters are honest; wavefronts aligned at x 972 by a shared bright tip dot) + hook already on screen at t=0 in the headline band (x 108, Cairo 1000 ~100, 2 lines): 'Red, blue: same speed.' / 'Different how?'. Small tag 'in empty space' (48, textDim) at y 1300 on cue l1 'الفضا'. Signal: both tip dots flash on cue 'السرعة'.","tts_text":"في الفضا، الضوء الأحمر والأزرق بنفس السرعة… أُمال إيه المختلف؟","screen_text":"Red, blue: same speed. Different how?"},{"id":"l2","visual":"Hook text exits; headline 'Light travels as waves' (Cairo 1000, 80) on cue l2 'waves'. The two waves keep scrolling; on cue 'طاقة' small gold energy sparks ride the crests left → right (YK.particles, seeded), label 'carry energy' (56, gold).","tts_text":"الضوء بيمشي على شكل waves شايلة طاقة.","screen_text":"Light travels as waves that carry energy"},{"id":"l3","visual":"Red wave freezes and moves to the stage centre (y 1000, amplitude 160). Order follows the voice: on cue l3 'wavelength' a double-headed YK.arrow spans two neighbouring crests with label 'wavelength' (56) above it; on cue 'المسافة' the definition YK.para('Wavelength: distance between two neighbouring crests', x 108, y 1420, {size 48, maxWidth 864, keys:['crests']}); on cue 'crests' gold dots pop on the two crests and the key word 'crests' in the line pulses gold (no separate 'crest' tags: 3 text blocks max).","tts_text":"الـ wavelength: المسافة بين اتنين crests جنب بعض، يعني قمتين.","screen_text":"Wavelength: distance between two neighbouring crests"},{"id":"l4","visual":"Red wave scrolls again (720 px/s); a vertical dashed marker line at x 540. On cue l4 'frequency' label 'frequency' (56) + a crossing counter top-right of the stage: an integer computed from the phase (number of crests that crossed x 540 since the cue), drawn with YK.label mono 72 (not YK.counter, which is a tween). On cue 'ثانية' a 1-second sweep bar fills under the wave. Definition line 'waves passing a point each second' (48) at y 1420 on cue 'عدد'.","tts_text":"والـ frequency: عدد الموجات اللي بتعدي من نقطة في ثانية واحدة.","screen_text":"Frequency: number of waves passing a point in one second"},{"id":"l5","visual":"Blue wave slides in under the red one (red y 860, blue y 1180), same scroll speed, same marker at x 540. On cue l5 'wavelength' the blue wavelength arrow appears (shorter than red's); on cue 'أكتر' both crossing counters run for the same 1 s sweep: red shows exactly 3, blue exactly 5 (follows from 240 px vs 144 px at 720 px/s; computed, not typed) (counters side by side, mono 72).","tts_text":"نفس السرعة، والـ wavelength أقصر؟ يبقى موجات أكتر بتعدي كل ثانية.","screen_text":"Same speed + shorter waves → more waves each second"},{"id":"l6","visual":"Aha (hold ≥ 1.5 s, answers the hook): blue wave glows; label 'shorter wavelength' (56) on cue l6 'wavelength' and 'higher frequency' (56, gold) on cue 'frequency' beside the blue wave; red wave dims to 40% with tag 'longer wavelength, lower frequency' (48).","tts_text":"الأزرق: wavelength أقصر، فالـ frequency أعلى من الأحمر.","screen_text":"Blue: shorter wavelength, higher frequency"},{"id":"l7","style":"curious","visual":"Self-check on a NEW case (R8): two fresh waves, orange (#fb923c, wavelength 220 px) at y 860 and green (#34d399, wavelength 176 px), same 720 px/s scroll at y 1180, no numbers, no arrows. Question 'Which wave has the higher frequency?' (Cairo 1000, 72) in the headline band on cue l7 'frequency'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (pause_after_s 1.5).","tts_text":"طب الموجتين دول، البرتقاني والأخضر… مين الـ frequency بتاعه أعلى؟ فكّروا. <long pause>","screen_text":"Which wave has the higher frequency?"},{"id":"l8","visual":"Answer: on cue l8 'الأخضر' the green wave glows + YK.rightMark; wavelength arrows appear on both waves on cue 'wavelength' (green's visibly shorter); label 'Green: higher frequency' (56) on cue 'frequency'.","tts_text":"الأخضر: الـ wavelength أقصر، فالـ frequency أعلى.","screen_text":"Green: shorter wavelength, higher frequency"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Light and waves', line:'Shorter wavelength, higher frequency.', t, pulse:[{word:'wavelength', at:YK.cue('l9','wavelength')},{word:'frequency', at:YK.cue('l9','frequency')}]}) from cue l9 start, held ≥ 2.5 s. Loop (S5): last 0.8 s the card exits and the red and blue waves of frame 0 scroll side by side again.","tts_text":"wavelength أقصر، يبقى frequency أعلى.","screen_text":"Shorter wavelength, higher frequency."}],"logline":"Red and blue light travel at the same speed in empty space; they differ in wavelength (distance between two neighbouring crests) and frequency (waves passing a point each second): shorter wavelength, higher 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الفضا الضوء الأحمر والأزرق بنفس السرعة\nأُمال إيه المختلف\nالضوء بيمشي على شكل waves شايلة طاقة\nالـ wavelength المسافة بين اتنين crests\nجنب بعض يعني قمتين\nوالـ frequency عدد الموجات اللي بتعدي من\nنقطة في ثانية واحدة\nنفس السرعة والـ wavelength أقصر يبقى موجات\nأكتر بتعدي كل ثانية\nالأزرق wavelength أقصر فالـ frequency أعلى\nمن الأحمر\nطب الموجتين دول البرتقاني والأخضر مين الـ\nfrequency بتاعه أعلى فكّروا\nالأخضر الـ wavelength أقصر فالـ frequency\nأعلى\nwavelength أقصر يبقى frequency أعلى","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":8},{"id":"chem-s3-en.video-short-phys.em-spectrum","kind":"short","version":1,"ord":77,"content_lang":"ar-EG","primary_concept_id":"phys.em-spectrum","concepts":[{"concept_id":"phys.em-spectrum","role":"primary"}],"title":"Electromagnetic radiation (UV, X-rays, gamma)","payload":{"title":"Electromagnetic radiation (UV, X-rays, gamma)","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): a cloud (soft grey shapes) drifting left → right over a sun at the top of the stage (y 700); thin violet ray lines pass through the cloud down to a forearm silhouette (y 1300) whose skin patch slowly reddens (alpha 0→0.5 over the line) + hook already on screen at t=0 (headline band, Cairo 1000 ~110): 'Cloudy day.' / 'Still sunburnt?'. Signal: the reddened patch pulses on cue l1 'اتحرقت'.","tts_text":"يوم غيم ومفيش حر… وبرضه اتحرقت. إزاي؟","screen_text":"Cloudy day. Still sunburnt?"},{"id":"l2","visual":"Hook exits; headline 'Electromagnetic radiation' (Cairo 1000, 76, 2 lines) on cue l2 'electromagnetic'. Stage: a vertical spectrum ladder (one focal object, x 180–900, y 560–1600): 7 stacked bands (YK.roundRect, each 864×130, gap 8) all dark-outlined; on cue 'visible' only the middle band lights with a rainbow gradient + label 'Visible light' (56). On cue 'مش' the other 6 bands fade in as grey ghosts (no labels yet). Wave glyph on each band's right end, compressed more from top to bottom (shorter wavelength going down).","tts_text":"عيلة الـ electromagnetic radiation فيها الـ visible light… وأفراد عينينا مش بتشوفها.","screen_text":"Electromagnetic radiation: visible light + invisible rays"},{"id":"l3","visual":"[assumes tts fix: infrared dropped] Top two bands light on their cues (YK.cue('l3','radio'), 'microwaves'): labels 'Radio waves', 'Microwaves' (56, left-aligned at x 220) + small line icons on the right (radio tower and microwave oven, drawn with ctx paths). The third band (infrared) stays a dim unlabelled ghost (unvoiced term: not shown). Bracket on the left 'less energy' (48, textDim) on cue 'أقل'.","tts_text":"قبله: radio waves و microwaves، طاقتهم أقل.","screen_text":"Radio waves · Microwaves: less energy"},{"id":"l4","visual":"Bottom three bands light on cues 'ultraviolet', 'X-rays', 'gamma': labels 'Ultraviolet (UV)', 'X-rays', 'Gamma rays' (56); YK.icon 'sunscreen' on UV, an X-ray bone glyph on X-rays, YK.icon 'gamma' on gamma. On cue 'wavelength' a gold downward YK.arrow along the ladder's left edge labelled 'shorter wavelength, more energy' (48, gold) on cue 'أعلى'. Prereq chip YK.chip('Light and waves', {kind:'prereq'}) in the headline band on cue 'wavelength', ≤ 2 s (S6).","tts_text":"وبعده: ultraviolet و X-rays و gamma rays، wavelength أقصر وطاقة أعلى.","screen_text":"Ultraviolet · X-rays · Gamma rays: shorter wavelength, more energy"},{"id":"l5","visual":"Aha (hold ≥ 1.5 s, answers the hook): camera push (0.8 s) onto the Ultraviolet band and the Visible light band above it; the l1 forearm returns small at the right with the red patch; label 'invisible, but more energy' (56, gold) on cue l5 'طاقته'; violet rays from the UV band reach the patch on cue 'بيحرق'.","tts_text":"الـ ultraviolet بيحرق جلدك: مش بتشوفه، بس طاقته أعلى من الضوء.","screen_text":"Ultraviolet: invisible, but more energy than visible light"},{"id":"l6","visual":"Myth beat (concept misconception, R11, G40): camera to the Gamma rays band. Small wrong picture on cue l6 'particles': a burst of dots labelled 'particles' (48, coral), 60% size; YK.wrongMark on cue 'لأ' and it exits. Correct, bigger: a short-wavelength wave on the gamma band continuing the same ladder with the Visible light wave, label 'waves, like light' (56, mint) + YK.rightMark on cue 'waves'.","tts_text":"وناس فاكرة الـ gamma rays particles… لأ، دي waves زي الضوء.","screen_text":"Gamma rays = particles ✕   Waves, like light ✓"},{"id":"l7","style":"curious","visual":"Self-check on a NEW pair (R8): ladder dims to 30% except the Microwaves and X-rays bands (outlined; the gold l4 arrow and the 'less energy' bracket are hidden so the answer is not on screen). Question 'Microwaves or X-rays: which has more energy?' (Cairo 1000, 72, ≤ 2 lines) in the headline band on cue l7 'microwaves'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (pause_after_s 1.5).","tts_text":"طب الـ microwaves ولا الـ X-rays، مين طاقته أعلى؟ فكّروا. <long pause>","screen_text":"Microwaves or X-rays: which has more energy?"},{"id":"l8","visual":"Answer: X-rays band glows + YK.rightMark on cue l8 'X-rays'; the gold arrow from l4 re-draws between the two bands on cue 'wavelength'; label 'shorter wavelength, more energy' (56) on cue 'أعلى'.","tts_text":"الـ X-rays: الـ wavelength بتاعها أقصر، فطاقتها أعلى.","screen_text":"X-rays: shorter wavelength, more energy"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Electromagnetic radiation (UV, X-rays, gamma)', line:'From radio waves to gamma rays, energy increases.', t, pulse:[{word:'energy', at:YK.cue('l9','الطاقة')}]}) from cue l9 start, ≥ 2.5 s; 'radio waves' and 'gamma rays' also pulse on their cues. Loop (S5): last 0.8 s the cloud, sun and forearm of frame 0 return.","tts_text":"من radio waves لحد gamma rays: الطاقة بتزيد.","screen_text":"From radio waves to gamma rays, energy increases."}],"logline":"Visible light is one member of electromagnetic radiation; from radio waves through microwaves, infrared, visible, ultraviolet, X-rays to gamma rays the wavelength gets shorter and the energy higher, so invisible ultraviolet can burn the skin, and gamma rays are waves, not 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On cue l1 'implants' the implant glints; on cue 'جامد' a coral tag 'hard?' (56) pops beside it (the myth, to be refuted in l6).","tts_text":"titanium في implants السنان… عشان جامد؟ ناس كتير فاكرة كده.","screen_text":"Titanium implants. Because it's hard?"},{"id":"l2","visual":"Implant slides up and dims (35%). YK.elementCard(ctx, 300, 900, {sym:'Sc', config:'', w:380}) (w ≥ 380 for legible text; config hidden: not this concept) and a big aluminium block (YK.roundRect steel-grey, 360×420 at x 780, label 'Aluminium' 56); on cue l2 'scandium' a small pinch of Sc dots pours into the aluminium block (few dots: 'a little'); on cue 'alloy' the block becomes a mixed lattice (YK.lattice rows 4 cols 7, substitute 2 sites) labelled 'alloy' (56) + gloss tag 'a metal mixed with other elements' (48, textDim) on cue 'معدن' (plain gloss; alloys are taught later).","tts_text":"شوية scandium مع الـ aluminium يدّوا alloy، معدن متخلط بعناصر تانية.","screen_text":"Aluminum + a little scandium → alloy"},{"id":"l3","visual":"On cue l3 'خفيف' a feather tag 'light' (48) and on 'جامد' a hammer YK.hammer strike that bounces off ('very hard', 48); on cue 'MiG' YK.icon 'plane' (360 px, cyan) flies in left → right with label 'MiG fighter jets' (56).","tts_text":"خفيف وجامد جدًا، لطيارات الـ MiG الحربية.","screen_text":"Light, very hard alloy → MiG fighter jets"},{"id":"l4","visual":"Scene change (whip-pan allowed once): YK.elementCard(ctx, 300, 900, {sym:'Ti', config:'', w:380}) + aluminium block merge on cue l4 'titanium' into one bar labelled 'Ti–Al alloy' (56); YK.icon 'plane' and a simple space-shuttle line drawing appear right on cue 'طيارات' / 'فضا', label 'aircraft, space shuttles' (48).","tts_text":"والـ titanium مع الـ aluminium: طيارات وسفن فضا.","screen_text":"Titanium–aluminum alloys: aircraft, space shuttles"},{"id":"l5","visual":"Two bars side by side under a heat glow (orange gradient rising from y 1600, from cue l5 'الحرارة'): 'Aluminium' bar sags/bends on cue 'aluminium' with tag 'hardness decreases' (48, coral); 'Titanium' bar stays straight on cue 'titanium' with tag 'maintains its durability' (48, mint) on cue 'durability'.","tts_text":"في الحرارة العالية الـ aluminium بيلين، والـ titanium بيحافظ على الـ durability بتاعته.","screen_text":"High temperature: Ti maintains its durability; Al hardness decreases"},{"id":"l6","visual":"Myth → aha (concept misconception, R11; hold ≥ 1.5 s, answers the hook): the l1 implant returns to the centre at 100%. On cue l6 'جامد' the coral tag 'hard' gets YK.wrongMark (small, exits after 0.4 s). On cue 'inert' a bigger YK.termCard({term:'Inert', def:'The body does not reject it, and it causes no poisoning.', keys:['does not reject','no poisoning']}) (book wording; the one definition card) + YK.rightMark; body-tissue outline around the implant stays calm (no red) on cue 'رفض'.","tts_text":"والـ implants؟ مش عشان جامد… عشان inert، مبيتفاعلش، فمفيش رفض ولا تسمم.","screen_text":"Hard ✕   Inert: not rejected, no poisoning ✓"},{"id":"l7","style":"curious","visual":"Self-check on a NEW case (R8, not shown before): a knee-joint line drawing (custom ctx paths: steel ball-and-socket parts in a knee outline; there is no 'joint' icon in YK.ICONS) at the stage centre; two choice chips 'durability' / 'inert' (56) side by side under it. Question 'Artificial joints: durability or inert?' (Cairo 1000, 72) in the headline band on cue l7 'artificial'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (pause_after_s 1.5).","tts_text":"طب الـ artificial joints، durability ولا inert؟ فكّروا. <long pause>","screen_text":"Artificial joints: durability or inert?"},{"id":"l8","visual":"Answer: chip 'inert' glows + YK.rightMark on cue l8 'inert'; chip 'durability' dims with tag 'that's for heat' (48, textDim) on cue 'حرارة'.","tts_text":"inert، عشان جوه الجسم، مش في حرارة عالية.","screen_text":"Inert: inside the body, not at high temperature"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Economic importance of scandium and titanium', line:'Ti: inert in the body, durable at high temperatures.', t, pulse:[{word:'inert', at:YK.cue('l9','inert')},{word:'durable', at:YK.cue('l9','durable')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the rotating implant of frame 0 alone again.","tts_text":"titanium: inert في الجسم، و durable في الحرارة.","screen_text":"Ti: inert in the body, durable at high temperatures."}],"logline":"Each use has a reason: a little scandium in aluminum gives a light, very hard alloy (MiG jets); titanium-aluminum alloys fly because titanium maintains its durability at high temperatures; titanium is in implants because it is inert, not because it is 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في implants السنان عشان جامد ناس\nكتير فاكرة كده\nشوية scandium مع الـ aluminium يدّوا alloy\nمعدن متخلط بعناصر تانية\nخفيف وجامد جدًا لطيارات الـ MiG الحربية\nوالـ titanium مع الـ aluminium طيارات وسفن\nفضا\nفي الحرارة العالية الـ aluminium بيلين\nوالـ titanium بيحافظ على الـ durability\nبتاعته\nوالـ implants مش عشان جامد عشان inert\nمبيتفاعلش فمفيش رفض ولا تسمم\nطب الـ artificial joints durability ولا\ninert فكّروا\ninert عشان جوه الجسم مش في حرارة عالية\ntitanium inert في الجسم و durable في\nالحرارة","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":10},{"id":"chem-s3-en.video-short-chem.valency-formulas","kind":"short","version":1,"ord":81,"content_lang":"ar-EG","primary_concept_id":"chem.valency-formulas","concepts":[{"concept_id":"chem.valency-formulas","role":"primary"}],"title":"Valency and writing chemical formulas","payload":{"title":"Valency and writing chemical 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Signals: '2' flashes on cue l1 'اتنين', '3' on cue 'وتلاتة'.","tts_text":"chromium three oxide بنكتبه اتنين chromium وتلاتة oxygen… ليه الأرقام دي؟","screen_text":"Cr₂O₃: why 2 and 3?"},{"id":"l2","visual":"Formula shrinks to the top of the stage. Two atoms YK.atomDisc (Cr, O) with 'hands' (short bond stubs drawn as ctx lines around each disc): Cr with 3, O with 2, appear on cue l2 'valency'; label 'valency' (56) + definition line 'the combining power of an element' (48) on cue 'قدرته'. Prereq chip YK.chip('Elements and their symbols', {kind:'prereq'}) ≤ 2 s.","tts_text":"كل element ليه valency: قدرته إنه يتحد مع غيره.","screen_text":"Valency: the combining power of an element"},{"id":"l3","visual":"Name 'chromium (III) oxide' (Cairo 800, 64) centred; on cue l3 'الروماني' the '(III)' glows gold and drops a '3' onto the Cr atom; on cue 'oxygen' a '2' drops onto the O atom. Labels 'Cr: 3' 'O: 2' via YK.label (mono 72).","tts_text":"الرقم الروماني بيقول: chromium valency تلاتة، و oxygen اتنين.","screen_text":"Chromium (III): valency 3 · Oxygen: valency 2"},{"id":"l4","visual":"On cue l4 'swap' the '3' and '2' arc across (crossing YK.arrow pair, 0.6 s): 3 lands as the O subscript slot, 2 as the Cr subscript slot; label 'swap' (56) on cue 'swap'.","tts_text":"اعمل swap: الـ valency بتاع كل واحد يبقى عدد ذرات التاني.","screen_text":"Swap the valencies"},{"id":"l5","visual":"Aha (hold ≥ 1.5 s, answers the hook): the l1 formula returns full size, YK.formula('Cr_{!{2}}O_{!{3}}') (mono 140) assembled from the swapped numbers on cue l5 'اتنين' / 'وتلاتة' + YK.rightMark; small 2 Cr + 3 O atom discs line up under it.","tts_text":"يبقى اتنين chromium وتلاتة oxygen… من غير حفظ.","screen_text":"Cr₂O₃ ✓"},{"id":"l6","visual":"New row (y 1300): YK.formula 'Zn2O2' (mono 96) appears on cue l6 'zinc' with name 'zinc oxide' (48); on cue 'simplify' both 2s divide (÷2 tag, 48) and the formula crossfades to 'ZnO' on cue 'واحد'; label 'simplify' (56).","tts_text":"ولو الرقمين يتقسموا، simplify: zinc اتنين و oxygen اتنين يبقوا واحد وواحد.","screen_text":"Simplify: Zn₂O₂ → ZnO"},{"id":"l7","style":"curious","visual":"Self-check on a NEW case (R8): stage clears; name 'iron (II) oxide' (Cairo 800, 72) centred with YK.formula 'Fe' and 'O' (mono 120) and two empty subscript slots drawn as dashed YK.roundRect boxes (never the string 'Fe_ O_': '_' is subscript syntax). Question 'Iron (II) oxide: formula?' (Cairo 1000, 72) in the headline band on cue l7 'formula'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (pause_after_s 1.5).","tts_text":"طب iron two oxide… الـ formula بتاعه إيه؟ فكّروا. <long pause>","screen_text":"Iron (II) oxide: formula?"},{"id":"l8","visual":"Answer: on cue l8 'swap' YK.formula 'Fe2O2' (mono 110) fills the slots; on cue 'simplify' ÷2 and morph to 'FeO' (mono 130) + YK.rightMark on cue 'واحد'.","tts_text":"الـ swap يدّي اتنين واتنين، وبعد الـ simplify: iron واحد و oxygen واحد.","screen_text":"Fe₂O₂ → FeO"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Valency and writing chemical formulas', line:'Valencies → swap → simplify.', formula:'Cr2O3', t, pulse:[{word:'swap', at:YK.cue('l9','swap')},{word:'simplify', at:YK.cue('l9','simplify')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the big Cr₂O₃ of frame 0 with its pulsing 2 and 3.","tts_text":"valencies، swap، simplify… بالترتيب ده.","screen_text":"Valencies → swap → simplify."}],"logline":"Cr2O3 is not memorised: read the valencies (chromium (III) = 3, oxygen = 2), swap them, then simplify when both numbers divide (Zn2O2 → 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Labels 'nitrogen', 'hydrogen', 'ammonia' (48) under the molecules on their cues.","tts_text":"الـ nitrogen والـ hydrogen بيدّوا ammonia… بس عدّ الذرات: متساوية؟","screen_text":"N₂ + H₂ → NH₃: do the atoms add up?"},{"id":"l2","visual":"Atom tally under each side (YK.counter, mono 72): 'N: 2' left on cue l2 'اتنين', 'N: 1' right on cue 'واحد'; a coral '≠' between them on cue 'مشكلة'; one N atom on the left blinks with no partner.","tts_text":"الشمال فيه اتنين nitrogen، واليمين واحد بس. ودي مشكلة.","screen_text":"N: 2 on the left, 1 on the right"},{"id":"l3","visual":"No tilted balance (N₂ + H₂ has 4 atoms and NH₃ has 4: a balance tipped by 'more atoms' would be false). Atom tiles instead: under each side the atoms as YK.atomDisc rows (left N N / H H, right N / H H H); on cue l3 'ذرة' the unmatched left N tile flashes coral; headline 'No atom is created or destroyed' (72) on cue 'بتتخلق'; a ghost N tile fading away gets a small YK.wrongMark on cue 'بتختفي' (atoms cannot vanish).","tts_text":"مفيش ذرة بتتخلق ولا بتختفي، فلازم يتساووا.","screen_text":"No atom is created or destroyed"},{"id":"l4","visual":"On cue l4 'coefficient' a gold slot opens before NH₃ in the formula; label 'coefficient' (56) + 'the number before a formula' (48) on cue 'رقم'; a '×' sweep over the whole NH₃ on cue 'بيضرب'.","tts_text":"الحل: coefficient، رقم قبل الـ formula بيضرب كل اللي فيها.","screen_text":"Coefficient: the number before a formula"},{"id":"l5","visual":"Guardrail beat (lesson trap, coral ✕ smaller than ✓): a small wrong edit 'H2O → H2O2' (mono 64, coral) on cue l5 'subscript' with label 'subscript' (48) and YK.wrongMark on cue 'هتتغير' + tag 'different substance' (48); exits after 1 s.","tts_text":"وماتلعبش في الـ subscript: الـ substance نفسها هتتغير.","screen_text":"Coefficients only, never subscripts"},{"id":"l6","visual":"Aha (hold ≥ 1.5 s, answers the hook): coefficients drop into the formula YK.formula('N2 + !{3}H2 -> !{2}NH3'): the 3 on cue l6 'تلاتة', the 2 on cue 'واتنين' (molecule groups multiply below: 3 H₂, 2 NH₃); tallies update 'N: 2 = 2' on cue 'nitrogen', 'H: 6 = 6' on cue 'hydrogen'; the atom-tile rows match side to side (all mint) + YK.rightMark.","tts_text":"تلاتة قبل الـ hydrogen، واتنين قبل الـ ammonia: اتنين nitrogen وستة hydrogen في الناحيتين.","screen_text":"N₂ + 3H₂ → 2NH₃ ✓   N 2 = 2 · H 6 = 6"},{"id":"l7","style":"curious","visual":"Self-check on a NEW equation (R8; S3b: the N₂ equation and tiles clear first, so one equation on screen): YK.formula('H2 + Cl2 -> HCl') (mono 100) with an empty dashed gold coefficient slot drawn before HCl (YK.roundRect; '{?}' is not kit syntax); molecules under it: YK.molecule H2, and Cl2 / HCl built with atoms:[…] + bonds (not in YK.MOLECULES). Question 'Balance: H₂ + Cl₂ → HCl' (Cairo 1000, 72) on cue l7 'chlorine'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (pause_after_s 1.5).","tts_text":"طب الـ hydrogen مع الـ chlorine بيدّوا hydrogen chloride… توازنها إزاي؟ فكّروا. <long pause>","screen_text":"Balance: H₂ + Cl₂ → HCl"},{"id":"l8","visual":"Answer: '!{2}' fills the slot on cue l8 'اتنين' + a second HCl molecule appears; tallies 'H: 2 = 2', 'Cl: 2 = 2' (mono 64) on cue 'واتنين' + YK.rightMark.","tts_text":"اتنين قبل الـ hydrogen chloride، وكده اتنين واتنين في كل ناحية.","screen_text":"H₂ + Cl₂ → 2HCl"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Writing and balancing chemical equations', line:'Balance with coefficients; count every atom.', formula:'N2 + 3H2 -> 2NH3', t, pulse:[{word:'coefficients', at:YK.cue('l9','coefficients')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the bobbing N2 + H2 → NH3 molecules of frame 0.","tts_text":"وازن بالـ coefficients، وعدّ كل ذرة.","screen_text":"Balance with coefficients; count every atom."}],"logline":"N2 + H2 → NH3 loses atoms on paper; no atom is created or destroyed, so we balance with coefficients only, never subscripts, and count every atom: N2 + 3H2 → 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Hook in the band (Cairo 1000 ~110): 'Black powder:' / 'used up?'. Tag 'oxygen' (48) rises with the bubbles on cue l1 'oxygen'; the powder glows on cue 'البودرة'.","tts_text":"رشة بودرة سودة في الـ hydrogen peroxide… والـ oxygen بيطلع بسرعة. البودرة اتستهلكت؟","screen_text":"Black powder: used up?"},{"id":"l2","visual":"Myth beat (recorded misconception, R11, G40), part 1: small coral card 'used up, little by little?' (48, 60% size) beside the beaker on cue l2 'بتخلص'; a lab balance (YK.balance, level) slides in on cue 'نوزنها'.","tts_text":"ناس كتير فاكرة إنها بتخلص شوية بشوية… تعالوا نوزنها.","screen_text":"Used up, little by little?"},{"id":"l3","visual":"Top → bottom YK.flow layout 'col', 4 small nodes on their cues: 'weigh' (cue l3 'نوزنها'), 'react' ('نحطها'), 'filter, dry' ('نفلترها'), 'weigh again' ('تاني'); a black powder heap (custom: there is no kit icon for it) travels down the steps; the balance holds the powder against a fixed brass weight (no numbers).","tts_text":"نوزنها، نحطها، نفلترها وننشفها… ونوزنها تاني.","screen_text":"Weigh → react → filter, dry → weigh again"},{"id":"l4","visual":"Aha (hold ≥ 1.5 s, answers the hook): the balance settles level again on cue l4 'mass' (gold glow) + label 'same mass' (56); the coral 'used up' card gets YK.wrongMark and exits; YK.rightMark + label 'not used up' (48, mint) on cue 'فضلت'.","tts_text":"نفس الـ mass بالظبط، يعني فضلت زي ما هي.","screen_text":"Same mass: not used up ✓"},{"id":"l5","visual":"The one definition card (S7b): YK.termCard({term:'Catalyst', def:'A substance that speeds up a chemical reaction without being used up or changed.', keys:['speeds up','without being used up']}) on cue l5 'catalyst'; key words turn gold on 'بيسرّع' and 'بيخلص'.","tts_text":"ده اسمه catalyst: بيسرّع التفاعل، وهو نفسه مش بيخلص.","screen_text":"Catalyst: speeds up a chemical reaction without being used up"},{"id":"l6","visual":"The one equation (S3b): YK.formula('2H2O2 ->[!{MnO2}] 2H2O + O2', mono 64) builds at y 1000 on cue l6 'المعادلة'; a ghost 'MnO₂' tries the reactant side and gets a small ✕ on cue 'مش'; the real MnO₂ drops onto the arrow (gold) on cue 'فوق' + small label 'over the arrow' (48).","tts_text":"وفي المعادلة، الـ manganese dioxide بنكتبه فوق السهم… مش مع المتفاعلات.","screen_text":"2H₂O₂ →[MnO₂] 2H₂O + O₂"},{"id":"l7","style":"curious","visual":"Self-check on a NEW question (R8: amount vs speed never shown): two beakers of H₂O₂, left with black powder (fizzing), right labelled 'no MnO₂' (48, few slow bubbles); an empty gas cylinder above each; question in the band (Cairo 1000, 64) on cue l7 'oxygen'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; checkPause would stamp its own ✓) through the stitched silence (trailing <long pause> stripped, pause_after_s 1.5).","tts_text":"طب من غيره، الـ oxygen في الآخر أقل ولا نفس الكمية؟ فكّروا. <long pause>","screen_text":"Without MnO₂: less oxygen in the end, or the same?"},{"id":"l8","visual":"Answer: both cylinders fill — left fast, right slowly — and end at the same level (gold line) on cue l8 'نفس'; YK.rightMark; label 'a catalyst changes the speed' (48) on cue 'catalyst'.","tts_text":"نفس الكمية، بس أبطأ… الـ catalyst بيغيّر السرعة، مش الكمية.","screen_text":"Same amount, only slower: a catalyst changes the speed"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Catalyst', line:'A catalyst speeds up a reaction without being used up.', formula:'->[MnO2]', t, pulse:[{word:'catalyst', at:YK.cue('l9','catalyst')}, {word:'speeds up', at:YK.cue('l9','بيسرّع')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the foaming beaker of frame 0 with the powder at the bottom.","tts_text":"يعني الـ catalyst بيسرّع التفاعل، وهو نفسه مش بيخلص.","screen_text":"A catalyst speeds up a reaction without being used up."}],"logline":"A pinch of black manganese dioxide makes hydrogen peroxide release oxygen fast, and after filtering, drying and weighing it has the same mass: a catalyst speeds up a chemical reaction without being used up, is written over the arrow, and gives the same product only faster. New term: 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بودرة سودة في الـ hydrogen peroxide\nوالـ oxygen بيطلع بسرعة البودرة اتستهلكت\nناس كتير فاكرة إنها بتخلص شوية بشوية\nتعالوا نوزنها\nنوزنها نحطها نفلترها وننشفها ونوزنها تاني\nنفس الـ mass بالظبط يعني فضلت زي ما هي\nده اسمه catalyst بيسرّع التفاعل وهو نفسه\nمش بيخلص\nوفي المعادلة الـ manganese dioxide بنكتبه\nفوق السهم مش مع المتفاعلات\nطب من غيره الـ oxygen في الآخر أقل ولا نفس\nالكمية فكّروا\nنفس الكمية بس أبطأ الـ catalyst بيغيّر\nالسرعة مش الكمية\nيعني الـ catalyst بيسرّع التفاعل وهو نفسه\nمش بيخلص","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":13},{"id":"chem-s3-en.video-short-chem.metal-properties","kind":"short","version":1,"ord":87,"content_lang":"ar-EG","primary_concept_id":"chem.metal-properties","concepts":[{"concept_id":"chem.metal-properties","role":"primary"}],"title":"Properties of metals and non-metals","payload":{"title":"Properties of metals and non-metals","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): YK.hammer already swinging at t=0 (p from 0 at t=0, first impact before 1 s) over two lumps side by side (x 330 silver 'Aluminium' lump, x 750 yellow 'Sulfur' lump, labels 48) + hook on screen at t=0 (headline band, Cairo 1000 ~100): 'Hammer it:' / 'foil… or powder?'. On cue l1 'ورق' the aluminium lump flattens into a thin shiny sheet; on cue 'بودرة' the sulfur lump shatters into yellow powder (seeded YK.rng fragments).","tts_text":"اخبط حتة aluminium بالشاكوش تبقى ورق… واخبط الـ sulfur يبقى بودرة. ليه؟","screen_text":"Hammer it: foil… or powder?"},{"id":"l2","visual":"Tags under each: 'metal' (56, cyan) on cue l2 'metal', 'non-metal' (56, amber) on cue 'non-metal'. Prereq chip YK.chip('Elements and their symbols', {kind:'prereq'}) at the top of the stage ≤ 2 s.","tts_text":"الـ aluminium metal، والـ sulfur non-metal، وخواصهم مختلفة خالص.","screen_text":"Aluminum: metal · Sulfur: non-metal"},{"id":"l3","visual":"Zoom to the aluminium (camera 0.8 s): YK.lattice(rows 5, cols 8, slip driven by the impact value returned by YK.hammer(ctx, x, y, {p: YK.prog(t, YK.cue('l3','malleable'), +0.8)})): rows slide, the block spreads into a sheet without breaking. Label 'malleable' (56) on cue 'malleable', sub-label 'hammered into sheets' (48) on cue 'ألواح'.","tts_text":"معظم الـ metals malleable: تتطرق وتبقى ألواح من غير ما تتكسر.","screen_text":"Malleable: hammered into sheets"},{"id":"l4","visual":"The sheet rolls and is pulled to the right into a long thin wire (draw-out animation, YK.prog from cue l4 'ductile' over 1 s), YK.icon 'cable' at the wire end; label 'ductile' (56) + 'drawn into wires' (48) on cue 'أسلاك'.","tts_text":"وكمان ductile: تتسحب وتبقى أسلاك رفيعة.","screen_text":"Ductile: drawn into wires"},{"id":"l5","visual":"Wire gets a moving specular glint on cue l5 'shiny' (label 'shiny', 48); on cue 'conductors' a lamp (YK.icon 'lamp') at the wire end lights and a heat shimmer runs along it; label 'good conductors' (56) and small tags 'heat · electricity' (48) on cue 'للحرارة'.","tts_text":"وهي shiny، و good conductors للحرارة والكهربا.","screen_text":"Shiny · good conductors of heat and electricity"},{"id":"l6","visual":"Aha (hold ≥ 1.5 s, answers the hook): split screen top/bottom: aluminium sheet + wire (top, y 800) vs sulfur powder pile (bottom, y 1250). On cue l6 'sulfur' a small yellow sulfur lattice is struck: YK.lattice({blocked:true}) layers try to slide and spring back, then drawn crack lines split it into seeded fragments on cue 'بيتكسر' (the kit lattice has no crack mode); label 'not malleable' (56, coral) on cue 'malleable'; tag 'most solid non-metals: break' (48) on cue 'بيتكسر'.","tts_text":"لكن الـ sulfur مش malleable، زي معظم الـ non-metals الصلبة: بيتكسر.","screen_text":"Sulfur: not malleable → powder"},{"id":"l7","style":"curious","visual":"Self-check on a NEW use (R8): a metal cooking pot on a flame at the stage centre (drawn: pot outline steel, flame orange, food steam). Question 'A pot passes heat to food. Which property?' (Cairo 1000, 72, ≤ 2 lines) in the headline band on cue l7 'حرارة'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (pause_after_s 1.5).","tts_text":"طب الحلة لازم توصّل حرارة النار للأكل… أنهي خاصية دي؟ فكّروا. <long pause>","screen_text":"A pot passes heat to food. Which property?"},{"id":"l8","visual":"Answer: heat arrows (orange YK.arrow ×3) run from the flame through the pot wall into the food on cue l8 'good' + YK.rightMark; label 'good conductor of heat' (56) on cue 'conductor'.","tts_text":"إنها good conductor للحرارة.","screen_text":"Good conductor of heat"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Properties of metals and non-metals', line:'Most metals: malleable, ductile, good conductors.', t, pulse:[{word:'malleable', at:YK.cue('l9','malleable')},{word:'ductile', at:YK.cue('l9','ductile')},{word:'conductors', at:YK.cue('l9','conductors')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the hammer swings over the two lumps of frame 0.","tts_text":"الـ metals غالبًا: malleable، ductile، good conductors كمان.","screen_text":"Most metals: malleable, ductile, good conductors."}],"logline":"Hammer aluminum and it becomes foil; hammer sulfur and it becomes powder: most metals are malleable, ductile, shiny and good conductors, while most solid non-metals are not malleable and 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حتة aluminium بالشاكوش تبقى ورق واخبط\nالـ sulfur يبقى بودرة ليه\nالـ aluminium metal والـ sulfur non-metal\nوخواصهم مختلفة خالص\nمعظم الـ metals malleable تتطرق وتبقى\nألواح من غير ما تتكسر\nوكمان ductile تتسحب وتبقى أسلاك رفيعة\nوهي shiny و good conductors للحرارة\nوالكهربا\nلكن الـ sulfur مش malleable زي معظم الـ\nnon-metals الصلبة بيتكسر\nطب الحلة لازم توصّل حرارة النار للأكل أنهي\nخاصية دي فكّروا\nإنها good conductor للحرارة\nالـ metals غالبًا malleable ductile good\nconductors كمان","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":14},{"id":"chem-s3-en.video-short-chem.acids-bases-salts","kind":"short","version":1,"ord":89,"content_lang":"ar-EG","primary_concept_id":"chem.acids-bases-salts","concepts":[{"concept_id":"chem.acids-bases-salts","role":"primary"}],"title":"Acids, bases and salts","payload":{"title":"Acids, bases and salts","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): a heap of blue copper (II) sulphate crystals (real colour, seeded facets glinting) at the stage centre next to a small salt shaker (white grains) + hook on screen at t=0 (headline band, Cairo 1000 ~100): 'CuSO₄: a salt' / 'you can't eat?'. Label 'copper (II) sulphate' (48) on cue l1 'copper'; a coral YK.wrongMark over a fork drawn with ctx paths on cue 'بياكله'.","tts_text":"الـ copper two sulphate ده salt… ومحدش بياكله! أُمال salt ليه؟","screen_text":"CuSO₄: a salt you can't eat?"},{"id":"l2","visual":"Crystals slide up and dim. YK.beaker(ctx, 360, 1050, 300, 380, {color:'rgba(200,220,255,0.35)', label:'H2SO4'}) appears on cue l2 'sulphuric'; label 'sulphuric acid' (56); YK.formula('!{H2}SO4') (mono 96) above; on cue 'hydrogen' the H₂ glows + label 'hydrogen' (48) (spoken term visible on its cue, L7).","tts_text":"خد الـ sulphuric acid: فيه hydrogen، وده المهم.","screen_text":"Sulphuric acid, H₂SO₄"},{"id":"l3","visual":"On cue l3 'base' black copper (II) oxide powder (real colour) pours into the beaker from the right; label 'base' (56) + 'copper (II) oxide, CuO' (48) on cue 'copper'. Prereq chip YK.chip('Valency and writing chemical formulas', {kind:'prereq'}) ≤ 2 s.","tts_text":"ونضيف عليه base: الـ copper two oxide، أسود كده.","screen_text":"Base: copper (II) oxide, CuO"},{"id":"l4","visual":"The one equation (S3b): YK.formula 'CuO + H2SO4 -> CuSO4 + H2O' (mono 64, fits x 108–972) builds left → right; on cue l4 'copper' a Cu tile slides into the H₂ slot of H₂SO₄ and the H₂ tile moves to join O → H₂O; the beaker liquid tweens to blue (YK.beaker mix → copper sulphate blue) on cue 'sulphate'.","tts_text":"الـ copper ياخد مكان الـ hydrogen، فيطلع copper sulphate ومية.","screen_text":"CuO + H₂SO₄ → CuSO₄ + H₂O"},{"id":"l5","visual":"Aha (hold ≥ 1.5 s, answers the hook): the l1 crystals return beside the beaker; YK.termCard({term:'Salt', def:'A compound formed when the hydrogen of an acid is replaced by a metal.' (book wording), keys:['hydrogen','metal']}) (the one definition card) on cue l5 'salt'; 'Cu' in CuSO4 glows on cue 'metal'.","tts_text":"يعني الـ salt: metal واخد مكان hydrogen الـ acid بتاعه.","screen_text":"Salt: a metal replaces the hydrogen of an acid"},{"id":"l6","visual":"[assumes tts fix: sulphates dropped, one new term on this line] The l1 salt shaker returns at the centre; on cue l6 'hydrochloric' YK.formula 'HCl' (mono 96) at left with label 'hydrochloric acid' (56); on cue 'chlorides' an arrow to YK.formula 'NaCl' (mono 96) beside the shaker + label 'chlorides' (56, gold): table salt is a chloride, echoing the hook.","tts_text":"والاسم جاي من الـ acid: الـ hydrochloric acid بيدّي chlorides.","screen_text":"Hydrochloric acid → chlorides"},{"id":"l7","style":"curious","visual":"Self-check on a NEW salt (R8): white calcium chloride grains in a dish at the stage centre, label 'calcium chloride, CaCl₂' (56); two empty acid chips 'sulphuric acid' / 'hydrochloric acid' under it. Question 'Calcium chloride: from which acid?' (Cairo 1000, 72) on cue l7 'calcium'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (pause_after_s 1.5).","tts_text":"طب الـ calcium chloride… جه من أنهي acid؟ فكّروا. <long pause>","screen_text":"Calcium chloride: from which acid?"},{"id":"l8","visual":"Answer: chip 'hydrochloric acid' glows + YK.rightMark on cue l8 'hydrochloric'; on cue 'calcium' two HCl tiles: both H tiles leave and one Ca tile joins the two Cl tiles → 'CaCl2' (YK.formula, mono 80) (tile swap like l4, no equation; one Ca replaces two H).","tts_text":"من الـ hydrochloric acid، والـ calcium خد مكان الـ hydrogen بتاعه.","screen_text":"Hydrochloric acid: calcium replaced its hydrogen"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Acids, bases and salts', line:'Acid + base → salt + water.', t, pulse:[{word:'salt', at:YK.cue('l9','salt')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the blue crystal heap of frame 0.","tts_text":"acid مع base يدّوا salt ومية.","screen_text":"Acid + base → salt + water."}],"logline":"Copper (II) sulphate is a salt nobody eats: a salt forms when a metal replaces the hydrogen of an acid; an acid and a base give a salt and water, and the salt's name comes from its acid (sulphuric → sulphates, hydrochloric → 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copper two sulphate ده salt ومحدش\nبياكله أُمال salt ليه\nخد الـ sulphuric acid فيه hydrogen وده\nالمهم\nونضيف عليه base الـ copper two oxide أسود\nكده\nالـ copper ياخد مكان الـ hydrogen فيطلع\ncopper sulphate ومية\nيعني الـ salt metal واخد مكان hydrogen الـ\nacid بتاعه\nوالاسم جاي من الـ acid الـ hydrochloric\nacid بيدّي chlorides\nطب الـ calcium chloride جه من أنهي acid\nفكّروا\nمن الـ hydrochloric acid والـ calcium خد\nمكان الـ hydrogen بتاعه\nacid مع base يدّوا salt ومية","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":15},{"id":"chem-s3-en.video-short-chem.oxides","kind":"short","version":2,"ord":91,"content_lang":"ar-EG","primary_concept_id":"chem.oxides","concepts":[{"concept_id":"chem.oxides","role":"primary"}],"title":"Acidic and basic oxides","payload":{"title":"Acidic and basic 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Signal: tag 'H₂' (YK.label 56) rises with bubbles on cue l1 'hydrogen'.","tts_text":"الـ iron في الـ acid بيفور ويطلع hydrogen… طب الـ rust هيفور؟","screen_text":"Iron fizzes in acid. Rust?"},{"id":"l2","visual":"Zoom to the rust lump: it opens into a small grid of Fe + O discs (YK.atomDisc, alternating) on cue l2 'oxide'; label 'iron oxide' (56); tags 'metal' / 'oxygen' (48) on their cues.","tts_text":"الـ rust ده iron oxide، يعني metal و oxygen متحدين.","screen_text":"Rust = iron oxide (metal + oxygen)"},{"id":"l3","visual":"Label 'basic oxides' (56) on cue l3 'basic' above a row of 3 oxide formulas (YK.formula 'CuO', 'Na2O', 'FeO', mono 72; not MgO: it is the l7 check case and must stay new) appearing left → right; small word 'most' (48, gold) on cue 'ومعظم'. Prereq chip YK.chip('Acids, bases and salts', {kind:'prereq'}) ≤ 2 s.","tts_text":"ومعظم الـ metal oxides بنسميها basic oxides، زيه.","screen_text":"Most metal oxides: basic oxides"},{"id":"l4","visual":"Aha (hold ≥ 1.5 s, answers the hook): back to the right beaker: the rust lump dissolves (solid.p 1→0 from cue l4 'acid'), the liquid keeps its colour (no colour claim, G45), bubbles stay 0; word line 'basic oxide + acid → salt + water' (56) builds on cues 'salt' / 'ومية'; tag 'no gas' (56, mint) + YK.rightMark on cue 'غاز'.","tts_text":"فمع الـ acid تدّي salt ومية… من غير أي غاز.","screen_text":"Basic oxide + acid → salt + water (no gas)"},{"id":"l5","visual":"Particle view inset (y 1300): H tiles labelled 'acid's H' (48) meet O discs labelled 'oxide's O' (48) on cue l5 'hydrogen' and form YK.molecule({formula:'H2O'}) on cue 'مية'; label 'water' (48).","tts_text":"الـ hydrogen بتاع الـ acid مسك في الـ oxygen وعمل مية.","screen_text":"Acid's H + oxide's O → water"},{"id":"l6","visual":"Contrast row: YK.molecule({formula:'CO2'}) and a drawn SO₃ (YK.formula 'SO3' tag) on cue l6 'non-metal'; label 'acidic oxides' (56, amber) on cue 'acidic'; they drop into a water beaker whose litmus strip turns red on YK.cue('l6','acid',1) (real indicator colour; k=1 because the needle 'acid' also matches 'acidic' first).","tts_text":"ومعظم الـ non-metal oxides، acidic oxides: بتعمل acid في المية.","screen_text":"Most non-metal oxides: acidic oxides (water → acid)"},{"id":"l7","style":"curious","visual":"Self-check on a NEW reaction (R8): a beaker of dilute hydrochloric acid and a spoon of white magnesium oxide powder above it (not yet added). Question 'Magnesium oxide + hydrochloric acid: gas?' (Cairo 1000, 72, ≤ 2 lines) on cue l7 'magnesium'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (pause_after_s 1.5).","tts_text":"طب الـ magnesium oxide مع الـ hydrochloric acid… هيطلع غاز؟ فكّروا. <long pause>","screen_text":"Magnesium oxide + hydrochloric acid: gas?"},{"id":"l8","visual":"Answer: powder drops and dissolves, no bubbles, on cue l8 'لأ' + YK.rightMark; labels 'basic oxide' (48) on its cue and 'magnesium chloride + water' (56) on cue 'magnesium'.","tts_text":"لأ: basic oxide، فيدّي magnesium chloride ومية بس.","screen_text":"No gas: magnesium chloride + water"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Acidic and basic oxides', line:'Basic oxide + acid → salt + water.', t, pulse:[{word:'Basic oxide', at:YK.cue('l9','basic')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the two beakers of frame 0 (iron fizzing, rust calm).","tts_text":"basic oxide مع acid: salt ومية.","screen_text":"Basic oxide + acid → salt + water."}],"logline":"Iron fizzes in acid but rust (an iron oxide) does not: most metal oxides are basic oxides that react with an acid to give a salt and water, no gas; most non-metal oxides are acidic oxides that make acids with 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iron في الـ acid بيفور ويطلع hydrogen\nطب الـ rust هيفور\nالـ rust ده iron oxide يعني metal و oxygen\nمتحدين\nومعظم الـ metal oxides بنسميها basic\noxides زيه\nفمع الـ acid تدّي salt ومية من غير أي غاز\nالـ hydrogen بتاع الـ acid مسك في الـ\noxygen وعمل مية\nومعظم الـ non-metal oxides acidic oxides\nبتعمل acid في المية\nطب الـ magnesium oxide مع الـ hydrochloric\nacid هيطلع غاز فكّروا\nلأ basic oxide فيدّي magnesium chloride\nومية بس\nbasic oxide مع acid salt ومية","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":16},{"id":"chem-s3-en.video-short-chem.rusting-corrosion","kind":"short","version":1,"ord":93,"content_lang":"ar-EG","primary_concept_id":"chem.rusting-corrosion","concepts":[{"concept_id":"chem.rusting-corrosion","role":"primary"}],"title":"Rusting and corrosion","payload":{"title":"Rusting and corrosion","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): three YK.tube (x 300 / 540 / 780, y 1050, 160×520) each with a grey iron nail, a slow day-counter 'Day 1 → 7' (mono 56) ticking from t=0 + hook (headline band, Cairo 1000 ~100): 'Three iron nails.' / 'Which one rusts?'. Signal: the three nails glint in sequence on cue l1 'iron'.","tts_text":"تلات مسامير iron… مين هيصدّي؟","screen_text":"Three iron nails. Which one rusts?"},{"id":"l2","visual":"Tube contents appear on cues: tube 1 dry air + drying-agent granules at the bottom, closed stopper, label 'dry air' (48) on cue l2 'ناشف'; tube 2 boiled water with an oil layer on top, label 'boiled water + oil' (48) on cue 'مية'; tube 3 half water half air, open, label 'air + water' (48) on cue 'وهوا'.","tts_text":"هوا ناشف، مية من غير هوا، وهوا ومية.","screen_text":"Dry air · boiled water + oil · air + water"},{"id":"l3","visual":"Aha (hold ≥ 1.5 s, answers the hook): day counter hits 7; nail 3 turns red-brown (real rust colour, tween from cue l3 'التالت') + YK.rightMark; nails 1 and 2 stay grey; headline 'oxygen + moisture together' (72): 'oxygen' on cue 'oxygen', 'moisture' on cue 'moisture'.","tts_text":"التالت بس اللي صدّي: الـ rusting محتاج oxygen و moisture مع بعض.","screen_text":"Only air + water rusts: oxygen and moisture together"},{"id":"l4","visual":"Camera push on nail 3 (0.8 s): its surface pits slowly; label 'corrosion' (56) on cue l4 'corrosion' and 'metal slowly worn away by air' (48) on cue 'بيتآكل'.","tts_text":"والـ rusting نوع من الـ corrosion: metal بيتآكل بالراحة من الهوا.","screen_text":"Rusting = corrosion of iron"},{"id":"l5","visual":"YK.oxideSkin(ctx, 540, 1100, 760, 420, {metal:'Fe', porous:true, p:1, acid: YK.prog(t, YK.cue('l5','rusting'), +1.5), acidLabel:'', particleColor:YK.C.cyan, layerColor:'#8B3A1A', label:'rust', t}) cross-section; on cue l5 'porous' gaps in the layer light up; on cue 'وبيقشّر' flakes break off and fall; on cue 'rusting' the oxideSkin particles (here air and water, cyan, unlabelled) pass the gaps and pit fresh iron below; label 'porous' (56).","tts_text":"والـ rust نفسه porous، مليان خروم وبيقشّر… فالـ rusting يكمل لجوه.","screen_text":"Rust is porous: it flakes off, rusting continues"},{"id":"l6","visual":"Three coated nails in a row (≤ 3 items): painted (blue coat) on cue l6 'بندهن', oiled (glossy film) on 'بنزيّت', zinc-coated (silver-grey layer, label 'galvanizing (zinc)' 56) on cue 'galvanizing'; air/water particles bounce off all three (drawn dots with reflected paths; YK.particles has no bounce); tag 'keep air and water away' (48).","tts_text":"عشان كده بندهن، بنزيّت، أو بنعمل galvanizing بطبقة zinc عليه.","screen_text":"Paint, oil, galvanizing (zinc): keep air and water away"},{"id":"l7","style":"curious","visual":"Self-check on a NEW case (R8): a painted iron gate bar (dark green paint) at the stage centre with a deep diagonal scratch exposing grey iron, humid-air droplets around. Question 'Painted iron gate, deep scratch. Rust there?' (Cairo 1000, 72, ≤ 2 lines) on cue l7 'بوابة'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (pause_after_s 1.5).","tts_text":"طب بوابة iron متدهنة، واتخدشت خدش عميق… هتصدّي عند الخدش؟ فكّروا. <long pause>","screen_text":"Painted iron gate, deep scratch. Rust there?"},{"id":"l8","visual":"Answer: on cue l8 'أيوه' YK.rightMark; droplets and O₂ dots flow into the scratch on cue 'oxygen'; red-brown rust spreads along the scratch only on cue 'iron'.","tts_text":"أيوه: الـ oxygen والـ moisture وصلوا للـ iron هناك.","screen_text":"Yes: oxygen and moisture reach the iron"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Rusting and corrosion', line:'Rusting needs oxygen and moisture together.', t, pulse:[{word:'oxygen', at:YK.cue('l9','oxygen')},{word:'moisture', at:YK.cue('l9','moisture')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the three tubes of frame 0, counter back at 'Day 1'.","tts_text":"الـ rusting: oxygen و moisture مع بعض.","screen_text":"Rusting needs oxygen and moisture together."}],"logline":"Of three iron nails (dry air, boiled water under oil, air and water) only the one with oxygen and moisture together rusts; rusting is the corrosion of iron, porous rust flakes off so it continues, and paint, oil or galvanizing with zinc keep air and water 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مسامير iron مين هيصدّي\nهوا ناشف مية من غير هوا وهوا ومية\nالتالت بس اللي صدّي الـ rusting محتاج\noxygen و moisture مع بعض\nوالـ rusting نوع من الـ corrosion metal\nبيتآكل بالراحة من الهوا\nوالـ rust نفسه porous مليان خروم وبيقشّر\nفالـ rusting يكمل لجوه\nعشان كده بندهن بنزيّت أو بنعمل galvanizing\nبطبقة zinc عليه\nطب بوابة iron متدهنة واتخدشت خدش عميق\nهتصدّي عند الخدش فكّروا\nأيوه الـ oxygen والـ moisture وصلوا للـ\niron هناك\nالـ rusting oxygen و moisture مع بعض","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":17},{"id":"chem-s3-en.video-short-redox.basic","kind":"short","version":1,"ord":95,"content_lang":"ar-EG","primary_concept_id":"redox.basic","concepts":[{"concept_id":"redox.basic","role":"primary"}],"title":"Oxidation and reduction by oxygen","payload":{"title":"Oxidation and reduction by oxygen","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): a pink copper wire coil (real copper colour) already in a flame at t=0 (y 1000), its surface tweening to black; on cue l1 'hydrogen' it slides into a glass tube with a stream of H₂ (label 'H₂', YK.label 48) and the black fades back to pink on YK.cue('l1','copper',1) (the 2nd 'copper'; a cue needle is one word) + hook (headline band, Cairo 1000 ~100): 'Black copper turns' / 'pink again. How?'.","tts_text":"سلك copper في النار بيسودّ… وفي الـ hydrogen يرجع copper تاني. إزاي؟","screen_text":"Black copper turns pink again. How?"},{"id":"l2","visual":"Back in the flame: O₂ molecules (YK.molecule 'O2') land on the wire surface and Cu–O pairs form a black skin on cue l2 'oxygen'; label 'oxidation' (56) on cue 'oxidation' + 'gain of oxygen' (48, mint) on cue 'كسب'; tag 'copper (II) oxide, CuO' (48) on cue 'oxide'.","tts_text":"ده oxidation: الـ copper كسب oxygen وبقى copper oxide أسود.","screen_text":"Oxidation: gain of oxygen"},{"id":"l3","visual":"The one equation (S3b): YK.formula 'CuO + H2 -> Cu + H2O' (mono 80) builds at y 1400 left → right; on cue l3 'oxygen' the O tile leaves CuO and joins H₂ → H₂O (YK.molecule 'H2O'); label 'reduction' (56) on cue 'reduction' + 'loss of oxygen' (48, coral) on cue 'بيخسر'. Prereq chip YK.chip('Writing and balancing chemical equations', {kind:'prereq'}) ≤ 2 s.","tts_text":"وفي الـ hydrogen بيحصل reduction: الـ copper oxide بيخسر الـ oxygen بتاعه.","screen_text":"Reduction: loss of oxygen · CuO + H₂ → Cu + H₂O"},{"id":"l4","visual":"In the equation, 'CuO' glows gold on cue l4 'copper'; an arrow carries its O to H₂ on cue 'ادّى'; label under CuO 'oxidizing agent' (56) on cue 'oxidizing' + 'supplies oxygen' (48).","tts_text":"اللي ادّى الـ oxygen، الـ copper oxide، اسمه oxidizing agent هنا.","screen_text":"Oxidizing agent: supplies oxygen"},{"id":"l5","visual":"Aha (hold ≥ 1.5 s, answers the hook): the black-to-pink wire returns at the top; a coral small tag 'oxidizing agent → oxidized' with YK.wrongMark on cue l5 'خد', then bigger mint tag 'oxidizing agent: itself reduced' + YK.rightMark on cue 'reduction'.","tts_text":"خد بالك: الـ oxidizing agent نفسه حصله reduction، مش العكس.","screen_text":"Oxidizing agent: itself reduced"},{"id":"l6","style":"curious","visual":"Check setup on a NEW reaction (R8): a red-brown iron oxide lump (left) and YK.molecule({formula:'CO'}) (right, y 1050); on cue l6 'oxygen' an O disc moves from the lump to CO making CO₂ (YK.molecule 'CO2'), lump turns grey (iron). Labels 'carbon monoxide' and 'iron oxide' (48) on their cues. No equation on screen.","tts_text":"طب الـ carbon monoxide بياخد oxygen من الـ iron oxide هنا.","screen_text":"Carbon monoxide takes oxygen from iron oxide"},{"id":"l7","visual":"Question 'Which one is the oxidizing agent?' (Cairo 1000, 72) in the headline band on cue l7 'oxidizing'; both substances outlined, no highlight. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l7','فكّروا'), dur: YK.cue('l8') - that start, question:'', answer:''}) through the stitched silence (pause_after_s 1.5).","tts_text":"مين فيهم الـ oxidizing agent؟ فكّروا. <long pause>","screen_text":"Which one is the oxidizing agent?"},{"id":"l8","visual":"Answer: iron oxide outline glows gold + YK.rightMark on cue l8 'iron'; tag 'oxidizing agent: supplies oxygen' (48) on cue 'جه'.","tts_text":"الـ iron oxide، عشان الـ oxygen جه منه.","screen_text":"Iron oxide: it supplies the oxygen"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Oxidation and reduction by oxygen', line:'Oxidation: gain of oxygen. Reduction: loss of oxygen.', formula:'CuO + H2 -> Cu + H2O', t, pulse:[{word:'Oxidation', at:YK.cue('l9','oxidation')},{word:'Reduction', at:YK.cue('l9','reduction')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the copper coil in the flame of frame 0.","tts_text":"oxidation يعني كسب oxygen، و reduction خسارته.","screen_text":"Oxidation: gain of oxygen. Reduction: loss of oxygen."}],"logline":"A copper wire turns black in a flame (oxidation: gain of oxygen) and hydrogen turns it pink again by taking the oxygen away (reduction: loss of oxygen); copper (II) oxide supplies the oxygen, so it is the oxidizing agent and is itself 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copper في النار بيسود وفي الـ hydrogen\nيرجع copper تاني إزاي\nده oxidation الـ copper كسب oxygen وبقى\ncopper oxide أسود\nوفي الـ hydrogen بيحصل reduction الـ\ncopper oxide بيخسر الـ oxygen بتاعه\nاللي ادّى الـ oxygen الـ copper oxide اسمه\noxidizing agent هنا\nخد بالك الـ oxidizing agent نفسه حصله\nreduction مش العكس\nطب الـ carbon monoxide بياخد oxygen من الـ\niron oxide هنا\nمين فيهم الـ oxidizing agent فكّروا\nالـ iron oxide عشان الـ oxygen جه منه\noxidation يعني كسب oxygen و reduction\nخسارته","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":18},{"id":"chem-s3-en.video-short-te.uses-v-cr","kind":"short","version":1,"ord":97,"content_lang":"ar-EG","primary_concept_id":"te.uses-v-cr","concepts":[{"concept_id":"te.uses-v-cr","role":"primary"}],"title":"Economic importance of vanadium and chromium","payload":{"title":"Economic importance of vanadium and chromium","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): left a car spring (YK.icon 'spring', 280 px, at (330, 1000)) already bouncing (compress/rebound loop); right an amber-tinted glass pane (YK.roundRect 300×420 at (750, 1000), light glint sweeping); between them a gold '?' tile pulsing. Hook in the band at t=0 (Cairo 1000 ~100): 'Car springs, glass dyes:' / 'same element?'. Labels 'springs' (48) on cue l1 'springs', 'dyes' (48) on cue 'dyes'; the '?' tile flashes on cue 'العنصر'.","tts_text":"عربية فيها springs جامدة، وإزاز فيه dyes… نفس العنصر؟","screen_text":"Car springs, glass dyes: same element?"},{"id":"l2","visual":"Glass exits and the hook band clears. YK.lattice steel block (rows 5, cols 8, grey, x 180–900, y 760–1240), label 'steel' (48) on cue l2 'steel'; on cue 'vanadium' three YK.atomDisc (el 'V') drop in and land as lattice `substitute:[{r:1,c:2},{r:3,c:5},{r:2,c:6}]` with color YK.C.gold (only a few: small portion) + label 'vanadium' (48, gold) replacing 'steel'. On cue 'alloy' the block outline turns gold + label 'alloy' (56) replacing 'vanadium', and on cue 'معدن' the gloss 'a metal mixed with other elements' (40, textDim) under it. G16: each label replaces the previous one (≤ 2 text blocks at once).","tts_text":"شوية vanadium على الـ steel يدّوا alloy، معدن متخلط بعناصر تانية.","screen_text":"Steel + a small portion of vanadium → alloy"},{"id":"l3","visual":"The alloy block morphs into the car spring (YK.icon 'spring', 340 px): it compresses and rebounds 3× without cracking; label 'high hardness' (48) on cue l3 'جامد'; on cue 'corrosion' rain drops hit and slide off, no rust spots + label 'resists corrosion' (48, mint); on cue 'springs' label 'car springs' (56) replacing 'high hardness' (≤ 2 labels at once, G16).","tts_text":"جامد جدًا وبيقاوم الـ corrosion، فبيعملوا منه springs العربيات.","screen_text":"High hardness, resists corrosion → car springs"},{"id":"l4","visual":"YK.formula 'V2O5' (mono 96) at (540, 760) on cue l4 'vanadium' + name label 'vanadium pentoxide' (52) under it; on cue 'dyes' an amber tint flows from the formula into a ceramic plate (circle r 140, glaze shine) and the glass pane of l1 below it (no other labels); label 'dyes' (48).","tts_text":"وأكسيده، الـ vanadium pentoxide، بيدخل dyes للسيراميك والإزاز.","screen_text":"Vanadium pentoxide, V₂O₅: dyes"},{"id":"l5","visual":"Myth beat (recorded misconception, R11, G40): small coral card 'V₂O₅: only a dye' (48) at 60% size on cue l5 'dye'; YK.wrongMark on cue 'لأ', card exits 0.4 s later. Bigger, correct: the V₂O₅ formula tile sits on a flat slab (custom; NOT YK.surface, whose atom row would draw vanadium metal atoms); two small grey reactant discs land on the slab, join and leave as one molecule while the slab stays unchanged (steady gold outline) + label 'catalyst' (56, mint) + YK.rightMark on cue 'catalyst'. Prereq chip YK.chip('Catalyst', {kind:'prereq'}) near the top of the stage (y ≈ 560) ≤ 2 s on cue 'catalyst'.","tts_text":"ناس فاكرة إنه dye وبس… لأ، كمان catalyst مهم.","screen_text":"Only a dye ✕   Also a catalyst ✓"},{"id":"l6","visual":"YK.elementCard({sym:'Cr', nameEn:'Chromium', config:'', w:380}) slides in top-left of the stage on cue l6 'chromium' and exits as the formula lands; YK.formula 'K2Cr2O7' (mono 80) at (540, 950) + label 'potassium dichromate' (52) on cue 'potassium'; label 'oxidizing agent' (56, gold) on cue 'oxidizing'; on cue 'بيأكسد' an arrow (no text) from the K₂Cr₂O₇ tile to a grey tile 'substance' (48) that glows. Prereq chip YK.chip('Oxidation and reduction by oxygen', {kind:'prereq'}) near the top of the stage ≤ 2 s on cue 'oxidizing'.","tts_text":"وعند الـ chromium مركب اسمه potassium dichromate: ده oxidizing agent، بيأكسد غيره.","screen_text":"Potassium dichromate, K₂Cr₂O₇: oxidizing agent"},{"id":"l7","style":"curious","visual":"Self-check on a new case (R8: the video never says what happens to K₂Cr₂O₇ itself; targets the 'reducing agent' misconception): the K₂Cr₂O₇ tile and the 'substance' tile, the 'oxidizing agent' label hidden; two empty chips 'oxidation' / 'reduction' (48) under the K₂Cr₂O₇ tile on their cues. Question in the band (Cairo 1000, 64, ≤ 2 lines) on cue l7 'بيأكسد'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; checkPause would stamp its own ✓) through the stitched silence (trailing <long pause> stripped, pause_after_s 1.5).","tts_text":"وهو بيأكسد غيره، بيحصله oxidation ولا reduction؟ فكّروا. <long pause>","screen_text":"K₂Cr₂O₇ oxidizes a substance. Does K₂Cr₂O₇ undergo oxidation or reduction?"},{"id":"l8","visual":"Answer: the 'reduction' chip lights gold + YK.rightMark on cue l8 'reduction', 'oxidation' chip fades; label 'the oxidizing agent itself undergoes reduction' (48) on cue 'oxidizing'.","tts_text":"هو نفسه بيحصله reduction… لأنه الـ oxidizing agent هنا.","screen_text":"Reduction: the oxidizing agent itself undergoes reduction"},{"id":"l9","visual":"Voiced lock-in (S3; covers both elements): YK.takeaway({title:'Economic importance of vanadium and chromium', line:'Vanadium: springs. V₂O₅: catalyst. K₂Cr₂O₇: oxidizing agent.', t, pulse:[{word:'springs', at:YK.cue('l9','springs')}, {word:'catalyst', at:YK.cue('l9','catalyst')}, {word:'oxidizing agent', at:YK.cue('l9','oxidizing')}]}) ≥ 2.5 s (needs the l9 tts fix that voices potassium dichromate). Loop (S5): last 0.8 s the bouncing spring and the amber glass of frame 0.","tts_text":"الـ vanadium للـ springs، وأكسيده catalyst، والـ potassium dichromate ده oxidizing agent بيأكسد.","screen_text":"Vanadium: springs. V₂O₅: catalyst. K₂Cr₂O₇: oxidizing agent."}],"logline":"A car spring and a glass dye share one element: a small portion of vanadium in steel gives a very hard, corrosion-resistant alloy for car springs; vanadium pentoxide (V₂O₅) is a dye and also a catalyst; chromium's compound potassium dichromate (K₂Cr₂O₇) is an oxidizing agent, so it is itself reduced. New terms: vanadium pentoxide, potassium dichromate (alloy glossed; catalyst, corrosion, oxidizing agent are 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فيها springs جامدة وإزاز فيه dyes\nنفس العنصر\nشوية vanadium على الـ steel يدّوا alloy\nمعدن متخلط بعناصر تانية\nجامد جدًا وبيقاوم الـ corrosion فبيعملوا\nمنه springs العربيات\nوأكسيده الـ vanadium pentoxide بيدخل dyes\nللسيراميك والإزاز\nناس فاكرة إنه dye وبس لأ كمان catalyst مهم\nوعند الـ chromium مركب اسمه potassium\ndichromate ده oxidizing agent بيأكسد غيره\nوهو بيأكسد غيره بيحصله oxidation ولا\nreduction فكّروا\nهو نفسه بيحصله reduction لأنه الـ\noxidizing agent هنا\nالـ vanadium للـ springs وأكسيده catalyst\nوالـ potassium dichromate ده oxidizing\nagent بيأكسد","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":19},{"id":"chem-s3-en.video-short-chem.activity-series","kind":"short","version":1,"ord":99,"content_lang":"ar-EG","primary_concept_id":"chem.activity-series","concepts":[{"concept_id":"chem.activity-series","role":"primary"}],"title":"Chemical activity series of metals","payload":{"title":"Chemical activity series of metals","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): two YK.beaker of acid side by side (x 330 / 750, y 1050, 300×400): left a magnesium ribbon already fizzing at t=0 (bubbles 0.9), right a copper wire (solid copper colour), no bubbles. Hook in the band (Cairo 1000 ~100): 'Magnesium fizzes.' / 'Copper doesn't. Why?'. No separate metal labels (the hook already names them; G16): the left beaker flashes (YK.flashRect) on cue l1 'magnesium', the right one on cue 'copper'; 'acid' (44) under both beakers on cue 'acid'.","tts_text":"شريط magnesium في الـ acid بيفور… وسلك copper ولا حاجة. ليه؟","screen_text":"Magnesium fizzes. Copper doesn't. Why?"},{"id":"l2","visual":"Beakers shrink to the top corners; headline 'Chemical activity series' (Cairo 1000, 72) on cue l2 'chemical'. Stage: a vertical ladder (x 300–780, y 600–1500) of empty rungs, top → bottom, label 'metals' (48) on cue 'metals'; a gold gradient arrow down its left edge on cue 'الأنشط' with one tag 'most active' (40, gold) at its top (muted frame, L7). The headline replaces the hook in the band (YK.band).","tts_text":"بنرتّب الـ metals في chemical activity series، من الأنشط للأقل.","screen_text":"Chemical activity series"},{"id":"l3","visual":"On cue l3 'hydrogen' a dashed line across the ladder's middle with label 'hydrogen' (48); a 'magnesium' tile (silver, 48) slides onto a rung above it on cue 'magnesium'; a 'copper' tile (copper colour) onto a rung below it on cue 'copper'. Only these two metals: no unspoken symbols.","tts_text":"في الترتيب ده، الـ magnesium فوق الـ hydrogen، والـ copper تحته.","screen_text":"Magnesium: above hydrogen. Copper: below hydrogen."},{"id":"l4","visual":"Aha part 1 (answers the hook): the magnesium beaker returns beside the ladder; particle inset: H discs (YK.atomDisc el 'H') pushed out of the acid by Mg discs and paired into YK.molecule 'H2' bubbles on cue l4 'displace' + label 'displaces hydrogen' (52, gold); 'dilute acid' (44) on the beaker on cue 'dilute'; bubbles burst on 'فيفور'.","tts_text":"اللي فوق الـ hydrogen بيعمله displace من الـ dilute acid، فيفور.","screen_text":"Above hydrogen: displaces it from dilute acid"},{"id":"l5","visual":"Aha part 2 (hold ≥ 1.5 s): the copper beaker beside the copper tile stays calm (no bubbles); label 'no reaction' (52, textDim) on cue l5 'تفاعل'; the dashed hydrogen line glows as the divider.","tts_text":"واللي تحته مبيقدرش… فمفيش تفاعل.","screen_text":"Below hydrogen: no reaction"},{"id":"l6","visual":"Magnesium tile glows with label 'active' (56, gold) on cue l6 'active' and a burst of bubbles on 'بسهولة'; a small coral hammer-and-dent glyph with 'hard' (48) and YK.wrongMark on cue 'جامد' (meaning of the word, the sense Ch.1 uses for chromium).","tts_text":"وخلي بالك: active يعني بيتفاعل بسهولة، مش جامد.","screen_text":"Active = reacts readily, not hard"},{"id":"l7","style":"curious","visual":"Self-check on a NEW metal (R8: iron never placed): a beaker of acid with an iron nail fizzing (bubbles 0.5) on cue l7 'iron'; beside the ladder an 'iron' tile with '?' (unplaced); the gold arrow hidden. Question in the band (Cairo 1000, 64) on cue 'iron'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; checkPause would stamp its own ✓) through the stitched silence (trailing <long pause> stripped, pause_after_s 1.5).","tts_text":"والـ iron بيفور في الـ acid: فوق الـ hydrogen ولا تحته؟ فكّروا. <long pause>","screen_text":"Iron fizzes in acid: above or below hydrogen?"},{"id":"l8","visual":"Answer: the iron tile slides onto a rung above the hydrogen line (below magnesium) + YK.rightMark on cue l8 'hydrogen'; label 'fizz = displaced hydrogen' (48) on cue 'displace'.","tts_text":"فوق الـ hydrogen، لأن الفوران معناه displace حصل.","screen_text":"Above hydrogen: the fizz shows it displaced hydrogen"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Chemical activity series of metals', line:'Above hydrogen: fizzes in dilute acid.', t, pulse:[{word:'hydrogen', at:YK.cue('l9','hydrogen')}, {word:'dilute acid', at:YK.cue('l9','dilute')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the two beakers of frame 0 (magnesium fizzing, copper calm).","tts_text":"فوق الـ hydrogen؟ في الـ dilute acid هيفور.","screen_text":"Above hydrogen: fizzes in dilute acid."}],"logline":"Magnesium fizzes in dilute acid but copper does nothing: the chemical activity series orders metals from most to least active; metals above hydrogen displace it from dilute acids, those below do not; 'active' means reacts readily, not hard (why Ch.1 calls chromium chemically active). New terms: chemical activity series, displace, 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magnesium في الـ acid بيفور وسلك\ncopper ولا حاجة ليه\nبنرتّب الـ metals في chemical activity\nseries من الأنشط للأقل\nفي الترتيب ده الـ magnesium فوق الـ\nhydrogen والـ copper تحته\nاللي فوق الـ hydrogen بيعمله displace من\nالـ dilute acid فيفور\nواللي تحته مبيقدرش فمفيش تفاعل\nوخلي بالك active يعني بيتفاعل بسهولة مش\nجامد\nوالـ iron بيفور في الـ acid فوق الـ\nhydrogen ولا تحته فكّروا\nفوق الـ hydrogen لأن الفوران معناه\ndisplace حصل\nفوق الـ hydrogen في الـ dilute acid هيفور","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":20},{"id":"chem-s3-en.video-short-te.chromium-oxide-layer","kind":"short","version":1,"ord":101,"content_lang":"ar-EG","primary_concept_id":"te.chromium-oxide-layer","concepts":[{"concept_id":"te.chromium-oxide-layer","role":"primary"}],"title":"Why chromium resists the effect of atmosphere","payload":{"title":"Why chromium resists the effect of 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Hook in the band (Cairo 1000 ~100): 'Chemically active.' / 'Shiny for years?'. Label 'chromium' (48) on the tap on cue l1 'chromium'; no separate 'chemically active' tag (the hook says it; G16): the hook's '!{Chemically active.}' turns gold via YK.band accentAt = cue 'chemically'. Prereq chip YK.chip('Chemical activity series of metals', {kind:'prereq'}) near the top of the stage (y ≈ 560, below the band) ≤ 2 s on cue 'active'.","tts_text":"حنفية chromium بتلمع سنين في الهوا… مع إنه chemically active. إزاي؟","screen_text":"Chemically active. Shiny for years?"},{"id":"l2","visual":"Myth beat (top recorded misconception, R11, G40): small coral tag 'unreactive' (48, 60%) on the tap on cue l2 'مبيتفاعلش'; YK.wrongMark on cue 'لأ', tag exits. YK.zoomThrough(ctx, t, {from: drawTap, to: drawCrRow, p: inOut over 1.0 s from cue 'لأ', focus: tap surface, badge: '×10^8'}) into the tap surface: a row of chromium atom discs (YK.atomDisc el 'Cr', x 160–920, y 1200); O₂ molecules land on the top row on cue 'oxygen' + label 'reacts with oxygen of air' (52, mint) + YK.rightMark.","tts_text":"ناس فاكرة إنه مبيتفاعلش… لأ، ده بيتفاعل مع الـ oxygen اللي في الهوا.","screen_text":"Unreactive ✕   Reacts with oxygen of air ✓"},{"id":"l3","visual":"Oxide units (custom: bigger warm-grey discs, one per O₂ that landed) grow on the top row of Cr discs left → right over 1 s from cue l3 'metal'; small gaps still show between them; label 'metal oxide' (52) on cue 'oxide'. Not YK.oxideSkin yet: its block has no atoms, and the disc model is what l4–l5 need.","tts_text":"فبيتكوّن metal oxide على سطحه.","screen_text":"A metal oxide forms on its surface"},{"id":"l4","visual":"Close-up comparison: one oxide unit next to one metal atom, with size brackets; headline 'Molecular volume' (56) on cue l4 'molecular'; label 'oxide' on cue 'oxide', 'metal atoms' on cue 'atoms'; the oxide swells to ~1.4× and a gold '>' appears between them on cue 'أكبر'; back in the row, every oxide unit swells the same way (the gaps shrink).","tts_text":"والـ molecular volume بتاع الـ oxide أكبر من الـ metal atoms نفسها.","screen_text":"Molecular volume of the oxide > that of the metal atoms"},{"id":"l5","visual":"Aha (hold ≥ 1.5 s, answers the hook): the swollen oxide units touch: on cue l5 'الفراغات' the last gaps close and the disc row cross-fades (0.4 s) into YK.oxideSkin({metal:'Cr', porous:false, p:1, acid:1, acidLabel:'O2', particleColor: oxygen colour}) drawn exactly over it: one continuous layer; label 'non-porous layer' (56, mint) on cue 'non-porous'; the O₂ particles bounce off the layer on cue 'oxygen' + YK.rightMark.","tts_text":"فيقفل الفراغات ويبقى layer مقفولة، non-porous، والـ oxygen مش بيعدّي.","screen_text":"Non-porous layer: no continued reaction with oxygen"},{"id":"l6","visual":"Second recorded misconception ('any oxide protects'): contrast panel below (y 1300–1600; chromium layer stays above, first-mentioned on top): YK.oxideSkin({metal:'Fe', porous:true, acid:1, acidLabel:'O2', layerColor: rust colour}); label 'iron' (48) on cue l6 'iron', 'rust: porous' (52, coral) on cue 'porous' (no separate 'rust' label, G16); O₂ particles pass through the holes on cue 'بيدخل' and the iron under it pits and thins on cue 'rusting'. No water dots (not voiced).","tts_text":"عكس الـ rust على الـ iron: porous، فالهوا بيدخل والـ rusting يكمّل.","screen_text":"Rust on iron: porous → rusting continues"},{"id":"l7","style":"curious","visual":"Self-check on a NEW metal (R8): an aluminum window frame (custom grey bars) in light rain, still shiny; question in the band (Cairo 1000, 64) on cue l7 'aluminium'; chromium panels hidden. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; checkPause would stamp its own ✓) through the stitched silence (trailing <long pause> stripped, pause_after_s 1.5).","tts_text":"طب الـ aluminium كمان active، وشبابيكه بتعيش سنين… ليه؟ فكّروا. <long pause>","screen_text":"Aluminum is active too, yet lasts in air. Why?"},{"id":"l8","visual":"Answer: zoom into the frame's surface: a continuous oxide layer forms (YK.oxideSkin({metal:'Al', porous:false}), silver tint) on cue l8 'oxide'; label 'non-porous oxide layer' (52) + YK.rightMark on cue 'non-porous'.","tts_text":"نفس الفكرة: oxide layer مقفولة، non-porous، بتحميه.","screen_text":"Same idea: a non-porous oxide layer"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Why chromium resists the effect of atmosphere', line:'Larger oxide volume → non-porous layer → protection.', t, pulse:[{word:'volume', at:YK.cue('l9','volume')}, {word:'non-porous', at:YK.cue('l9','non-porous')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the shiny tap of frame 0.","tts_text":"الـ oxide أكبر volume، فالـ layer non-porous بتحمي.","screen_text":"Larger oxide volume → non-porous layer → protection."}],"logline":"A chromium tap stays shiny for years although chromium is chemically active: it does react with oxygen of air, but the oxide's molecular volume is larger than that of the metal atoms, so a continuous non-porous layer blocks further reaction; porous rust on iron does not protect. New terms: molecular volume, non-porous, 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manganese","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): a railway track (YK.icon 'rail', 320 px, sliding left in a loop) at (330, 980) and a soft-drink can (YK.icon 'can', 240 px, slowly rotating) at (750, 980). Hook in the band (Cairo 1000 ~100): 'Rails and cans: manganese.' / 'Never pure?'. No separate labels or badge (the hook names both; G16): on cue l1 'manganese' the hook's '!{manganese}' turns gold (YK.band accentAt) and thin gold lines draw from it to both icons; the icons pulse once on cue 'لوحده'.","tts_text":"فيه manganese في قضبان القطر وفي العلب… بس عمره ما بيتستخدم لوحده. ليه؟","screen_text":"Rails and cans: manganese. Never pure?"},{"id":"l2","visual":"Myth beat (top recorded misconception, R11, G40): a grey metal bar tagged 'used pure' (48, coral, 60% size) on cue l2 'pure'; YK.wrongMark on cue 'لأ'; on cue 'brittle' the bar falls onto the floor and shatters into shards (YK.rng seed) — not YK.hammer: the hammer is kept for the l6 check so that case stays new (R8); label 'brittle: breaks when hit' (52) replaces 'used pure' on cue 'بيتكسر'.","tts_text":"ناس فاكرة إنه بيتستخدم pure… لأ، ده brittle، بيتكسر لو اتخبط.","screen_text":"Used pure ✕   Brittle: breaks when hit"},{"id":"l3","visual":"Correct version, bigger: YK.flow with explicit node positions (layout 'col' is a single chain, it cannot branch): node 'manganese' (sub 'brittle') at (540, 760); 'alloys' at (330, 1150) on cue l3 'alloys' and 'compounds' at (750, 1150) on cue 'compounds', edges manganese → alloys and manganese → compounds; gloss 'alloy: a metal mixed with other elements' (40, textDim) under 'alloys' on cue 'معدن'.","tts_text":"فبيدخل في alloys، يعني معدن متخلط بعناصر تانية، أو compounds كمان.","screen_text":"Always used as alloys or compounds"},{"id":"l4","visual":"Two bars side by side: 'ferromanganese' (52, gold, left, first mentioned) on cue l4 'ferromanganese' and 'steel' (48, right) on cue 'steel'; a scratch tip drags across both on cue 'أجمد': deep line on steel, barely a mark on ferromanganese, a gold '>' between the bars and band headline 'Harder than steel' (YK.band); on cue 'railway' the steel bar exits and the ferromanganese bar becomes the rail (YK.icon 'rail') with label 'railway track' (48). ≤ 2 labels at once (G16).","tts_text":"أولها الـ ferromanganese: أجمد من الـ steel، فبيتعمل منه railway track للقطر.","screen_text":"Ferromanganese: harder than steel → railway track"},{"id":"l5","visual":"An 'aluminum' tile (48) and a 'manganese' tile merge into a sheet on cue l5 'alloy', label 'aluminum–manganese alloy' (48); the sheet rolls into YK.icon 'can'; soft-drink drops splash inside, no corrosion spots + label 'resists corrosion' (48, mint) on cue 'corrosion'.","tts_text":"ومع الـ aluminium، الـ manganese بيعمل alloy بيقاوم الـ corrosion في العلب.","screen_text":"Aluminum–manganese alloy: resists corrosion → cans"},{"id":"l6","style":"curious","visual":"Self-check on a NEW object (R8: no hammer head made of Mn shown): a hammer whose head is labelled 'pure manganese' (48) raised over a nail, frozen; question in the band (Cairo 1000, 64) on cue l6 'شاكوش'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l6','فكّروا'), end: YK.cue('l7')}) (short.js; checkPause would stamp its own ✓) through the stitched silence (trailing <long pause> stripped, pause_after_s 1.5).","tts_text":"طب شاكوش من manganese pure… ينفع؟ فكّروا. <long pause>","screen_text":"A hammer head of pure manganese: good idea?"},{"id":"l7","visual":"Answer: the hammer swings on cue l7 'brittle' and its head cracks into shards on cue 'هيتكسر'; label 'No: brittle' (56) + YK.rightMark on the answer.","tts_text":"لأ، لأنه brittle، هيتكسر من أول خبطة.","screen_text":"No: brittle, it breaks when hit"},{"id":"l8","visual":"Voiced lock-in (S3): YK.takeaway({title:'Economic importance of manganese', line:'Brittle: always alloys or compounds.', t, pulse:[{word:'Brittle', at:YK.cue('l8','brittle')}, {word:'alloys', at:YK.cue('l8','alloys')}, {word:'compounds', at:YK.cue('l8','compounds')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the rail and the can of frame 0.","tts_text":"لأنه brittle، بيدخل alloys أو compounds، مش لوحده.","screen_text":"Brittle: always alloys or compounds."}],"logline":"Railway tracks and soft-drink cans contain manganese, yet it is never used pure: it is a brittle metal, so it is always used as alloys or compounds; ferromanganese is harder than steel (railway track) and aluminum-manganese alloy resists corrosion (cans). New terms: brittle, ferromanganese (alloy 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Hook in the band (Cairo 1000 ~100): 'Chlorine: 35.5.' / 'Half a neutron?'. Signals: '35.5' flashes on cue l1 'خمسة'; the cracked neutron on cue 'neutron'.","tts_text":"في الجدول، الـ chlorine خمسة وتلاتين ونص… هو الـ neutron بيتقسم نصين؟","screen_text":"Chlorine: 35.5. Half a neutron?"},{"id":"l2","visual":"Myth beat (recorded misconception, R11, G40): one small atom (60% size, coral outline) with tag '35.5 = mass number of one atom' (48, coral) on cue l2 'mass'; YK.wrongMark on cue 'لأ', it exits. Prereq chip YK.chip('Atomic number and mass number', {kind:'prereq'}) ≤ 2 s on cue 'mass'.","tts_text":"ناس فاكرة إنه الـ mass number بتاع atom واحد… لأ.","screen_text":"35.5 = mass number of one atom ✕"},{"id":"l3","visual":"Two nuclei side by side (packed clusters, proton discs and grey neutron discs): 'chlorine-35' (x 330) and 'chlorine-37' (x 750), names (48) under them on cue l3 'isotopes' + band headline 'Isotopes' (YK.band, gold) on the same cue (not a stage label, G16); one bracket under both with 'atomic number 17' (YK.label 48; the spoken term, L5) on cue 'atomic'; the two extra neutrons of chlorine-37 glow on cue 'neutrons'.","tts_text":"الـ chlorine عنده isotopes: نفس الـ atomic number، بس neutrons مختلفة.","screen_text":"Isotopes: same atomic number, different numbers of neutrons"},{"id":"l4","visual":"Aha (hold ≥ 1.5 s, answers the hook): a 10×10 grid of 100 small atom discs fills: 75 light-green 'chlorine-35' on cue l4 'تلات', 25 dark-green 'chlorine-37' on cue 'والربع' (labels '75%' / '25%', YK.label mono 52); below it a number line 35 — 37 with a gold pointer sliding to 35.5 on cue 'average' + label 'average 35.5' (YK.label 56).","tts_text":"تلات تربعه chlorine خمسة وتلاتين، والربع سبعة وتلاتين… فالـ average خمسة وتلاتين ونص.","screen_text":"75% chlorine-35 + 25% chlorine-37 → average 35.5"},{"id":"l5","visual":"The table tile returns small at the top with '35.5' labelled 'atomic mass' (52) on cue l5 'atomic'; on the number line a gold arrow pulls the pointer toward 35 (the common isotope's end) on cue 'بيشدّه'.","tts_text":"فالـ atomic mass في الجدول average، والأكتر بيشدّه ناحيته.","screen_text":"Atomic mass = average of the isotopes"},{"id":"l6","style":"curious","visual":"Self-check on a NEW element (R8: boron never shown): a 10×10 grid with 20 'boron-10' and 80 'boron-11' discs (labels '20%' / '80%') on cue l6 'boron'; an empty number line 10 — 11 with a '?' pointer; question in the band (Cairo 1000, 64, ≤ 2 lines) on cue 'boron'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l6','فكّروا'), end: YK.cue('l7')}) (short.js; checkPause would stamp its own ✓) through the stitched silence (trailing <long pause> stripped, pause_after_s 1.5).","tts_text":"والـ boron تمانين في المية منه حداشر… أقرب لعشرة ولا حداشر؟ فكّروا. <long pause>","screen_text":"Boron: 20% boron-10, 80% boron-11. Closer to 10 or 11?"},{"id":"l7","visual":"Answer: the pointer slides to 10.8 on cue l7 'عشرة' + label '10.8' (YK.label mono 64, gold) + YK.rightMark; the 80 boron-11 discs pulse on cue 'الأغلبية'.","tts_text":"أقرب لحداشر: عشرة فاصل تمانية، عشان الأغلبية حداشر.","screen_text":"Closer to 11: 10.8"},{"id":"l8","visual":"Voiced lock-in (S3): YK.takeaway({title:'Isotopes and average atomic mass', line:'Atomic mass: an average, not one atom.', t, pulse:[{word:'Atomic mass', at:YK.cue('l8','atomic')}, {word:'average', at:YK.cue('l8','average')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the chlorine tile '35.5' of frame 0, the neutron now whole.","tts_text":"الـ atomic mass ده average، مش atom واحد.","screen_text":"Atomic mass: an average, not one atom."}],"logline":"Chlorine's atomic mass is 35.5, but no atom holds half a neutron: chlorine has isotopes (same atomic number, different numbers of neutrons), and the table value is the average of chlorine-35 and chlorine-37 weighted by how common each is (75% and 25%). New terms: isotopes, atomic mass 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الجدول الـ chlorine خمسة وتلاتين ونص هو\nالـ neutron بيتقسم نصين\nناس فاكرة إنه الـ mass number بتاع atom\nواحد لأ\nالـ chlorine عنده isotopes نفس الـ atomic\nnumber بس neutrons مختلفة\nتلات تربعه chlorine خمسة وتلاتين والربع\nسبعة وتلاتين فالـ average خمسة وتلاتين ونص\nفالـ atomic mass في الجدول average والأكتر\nبيشدّه ناحيته\nوالـ boron تمانين في المية منه حداشر أقرب\nلعشرة ولا حداشر فكّروا\nأقرب لحداشر عشرة فاصل تمانية عشان الأغلبية\nحداشر\nالـ atomic mass ده average مش atom واحد","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":23},{"id":"chem-s3-en.video-short-phys.radioactivity-gamma","kind":"short","version":1,"ord":107,"content_lang":"ar-EG","primary_concept_id":"phys.radioactivity-gamma","concepts":[{"concept_id":"phys.radioactivity-gamma","role":"primary"}],"title":"Radioactivity and gamma rays","payload":{"title":"Radioactivity and gamma rays","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): a body silhouette (custom, soft grey) at the stage centre with a coral glowing spot deep inside the chest; at the left edge a small source capsule sends faint rays toward it (moving). Hook in the band (Cairo 1000 ~110): 'Treat a tumor' / 'from outside?'. Label 'tumor' (48) on the spot on cue l1 'tumor'.","tts_text":"فيه tumor جوه الجسم، والدكتور بيعالجه بأشعة من برّه. إزاي؟","screen_text":"Treat a tumor from outside?"},{"id":"l2","visual":"YK.zoomThrough(ctx, t, {from: drawBodyAndCapsule, to: drawNucleus, p: inOut over 1.0 s from l2 start, focus: the capsule, badge: '×10^12'}) into the capsule: one nucleus (packed proton/neutron discs) jittering; label 'unstable nucleus' (52) on cue l2 'unstable'; a few particles fly off on cue 'بتتفكك'. Prereq chip YK.chip('Isotopes and average atomic mass', {kind:'prereq'}) ≤ 2 s on cue 'isotopes'.","tts_text":"بعض الـ isotopes الـ nucleus بتاعها unstable، بتتفكك لوحدها.","screen_text":"Unstable nucleus: breaks down by itself"},{"id":"l3","visual":"Label 'radioactive isotope' (56, gold) on cue l3 'radioactive'; a violet wavy ray leaves the nucleus on cue 'radiation' + label 'radiation' (48); tag 'gamma rays' (48) replaces 'radiation' on the ray on cue 'gamma' (≤ 2 labels at once, G16). Prereq chip YK.chip('Electromagnetic radiation (UV, X-rays, gamma)', {kind:'prereq'}) ≤ 2 s.","tts_text":"ده اسمه radioactive isotope، وبيطلّع radiation زي الـ gamma rays كده.","screen_text":"Radioactive isotope → gives out radiation"},{"id":"l4","visual":"The gamma ray (YK.icon 'gamma' source at left) travels left → right straight through a sheet of paper, a wooden block and a metal plate (drawn objects, no labels; no hand or body part as a test object, no lead block: beyond the book, R3); label 'high penetrating power' (52, gold) on cue l4 'penetrating'; the ray glows brighter on cue 'طاقتها'.","tts_text":"والـ gamma rays طاقتها عالية جدًا، و penetrating power عالية.","screen_text":"Gamma rays: high penetrating power"},{"id":"l5","visual":"Aha (hold ≥ 1.5 s, answers the hook): back to the body: gamma rays from the source pass through the skin and converge on the tumor spot on cue l5 'tumor', which flares then dims; YK.rightMark.","tts_text":"فبتعدّي لحد الـ tumor جوه.","screen_text":"Gamma rays reach the tumor ✓"},{"id":"l6","visual":"Myth beat (recorded misconception, R11, G40): small apple (60%) with coral tag 'exposed = radioactive?' (48) on cue l6 'radioactive'; YK.wrongMark on cue 'لأ'; bigger, correct: rays pass through the apple and leave on cue 'بتعدّي', the apple stays plain (no glow) + label 'the rays pass through' (52, mint) + YK.rightMark.","tts_text":"ناس فاكرة إن اللي يتعرّض لها يبقى radioactive… لأ، هي بتعدّي وتمشي.","screen_text":"Exposed = radioactive ✕   The rays pass through ✓"},{"id":"l7","style":"curious","visual":"Self-check on a NEW object (R8): a sealed pack of syringes on a conveyor passes a gamma source (YK.icon 'gamma'), rays through the pack; question in the band (Cairo 1000, 64) on cue l7 'gamma'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; checkPause would stamp its own ✓) through the stitched silence (trailing <long pause> stripped, pause_after_s 1.5).","tts_text":"طب سرنجات متغلفة عدّت عليها gamma rays… بقت radioactive؟ فكّروا. <long pause>","screen_text":"Syringes exposed to gamma rays: radioactive now?"},{"id":"l8","visual":"Answer: the syringe pack moves on, plain (no glow) + YK.rightMark on cue l8 'لأ'; the source capsule glows with label 'radioactive isotope: in the source' (48) on cue 'radioactive'.","tts_text":"لأ، الأشعة عدّت ومشيت… والـ radioactive isotope فضل في المصدر.","screen_text":"No: the rays passed through; the isotope stays in the source"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Radioactivity and gamma rays', line:'Gamma rays: high penetrating power.', t, pulse:[{word:'Gamma rays', at:YK.cue('l9','gamma')}, {word:'penetrating power', at:YK.cue('l9','penetrating')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the body and the tumor spot of frame 0.","tts_text":"الـ gamma rays ليها penetrating power عالية.","screen_text":"Gamma rays: high penetrating power."}],"logline":"Doctors treat a tumour deep inside the body with rays from outside: a radioactive isotope has an unstable nucleus that breaks down and gives out radiation such as gamma rays, high-energy rays with high penetrating power; objects exposed to them do not become radioactive. New terms: unstable nucleus, radioactive isotope, penetrating 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tumor جوه الجسم والدكتور بيعالجه بأشعة\nمن برّه إزاي\nبعض الـ isotopes الـ nucleus بتاعها\nunstable بتتفكك لوحدها\nده اسمه radioactive isotope وبيطلّع\nradiation زي الـ gamma rays كده\nوالـ gamma rays طاقتها عالية جدًا و\npenetrating power عالية\nفبتعدّي لحد الـ tumor جوه\nناس فاكرة إن اللي يتعرّض لها يبقى\nradioactive لأ هي بتعدّي وتمشي\nطب سرنجات متغلفة عدّت عليها gamma rays بقت\nradioactive فكّروا\nلأ الأشعة عدّت ومشيت والـ radioactive\nisotope فضل في المصدر\nالـ gamma rays ليها penetrating power\nعالية","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":24},{"id":"chem-s3-en.video-short-te.uses-fe-co","kind":"short","version":1,"ord":109,"content_lang":"ar-EG","primary_concept_id":"te.uses-fe-co","concepts":[{"concept_id":"te.uses-fe-co","role":"primary"}],"title":"Economic importance of iron and cobalt","payload":{"title":"Economic importance of iron and cobalt","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13), split stage: top half (y 560–1080) a bed of grey iron pellets with small gas molecules flowing over it and an amber fuel drop dripping out; bottom half (y 1120–1640) a small capsule sending a violet beam to a body silhouette's coral tumor spot. Hook in the band (Cairo 1000 ~100): 'Iron → fuel?' / 'Cobalt → tumors?'. No separate labels (the hook names all four; G16): the top half flashes (YK.flashRect) on cue l1 'iron', the bottom half on cue 'cobalt'.","tts_text":"حتة iron بتساعد نعمل fuel، و cobalt بيعالج tumors. إزاي؟","screen_text":"Iron → fuel? Cobalt → tumors?"},{"id":"l2","visual":"Top half fills the stage: YK.surface(ctx, x, y, w, {metal:'Fe', molecules:[…H2 and CO entries: adsorb, weaken, leave]}) as the iron row; YK.molecule 'H2' and 'CO' stream in and land on cue l2 'water' + label 'water gas' (52); they leave as an amber fuel chain on cue 'fuel' + label 'fuel' (48).","tts_text":"وهنا الـ iron بيخلّي الـ water gas يتحوّل fuel بسرعة.","screen_text":"Water gas → fuel, over iron"},{"id":"l3","visual":"Tag 'catalyst' (48, gold) on the iron row on cue l3 'catalyst'; headline 'Fischer-Tropsch method' (64) in the band on cue 'fischer' (YK.cue('l3','fischer')). Chip below the band, near the top of the stage. Prereq chip YK.chip('Catalyst', {kind:'prereq'}) ≤ 2 s.","tts_text":"يعني catalyst، بطريقة اسمها Fischer-Tropsch هنا.","screen_text":"Fischer-Tropsch method: iron as a catalyst"},{"id":"l4","visual":"Myth beat (top recorded misconception, R11, G40): small coral steam puff with 'H₂O' (YK.label 48, 60% size) on cue l4 'مش' + YK.wrongMark, it exits; bigger, correct: a mixture of YK.molecule 'H2' (label 'hydrogen' 48, on cue 'hydrogen') and YK.molecule 'CO' (label 'carbon monoxide' 48, on cue 'carbon') + 'H₂ + CO' (YK.label mono 64) + YK.rightMark on 'متخلطين'.","tts_text":"والـ water gas مش بخار مية… ده hydrogen و carbon monoxide متخلطين.","screen_text":"Water gas: H₂O ✕   H₂ + CO ✓"},{"id":"l5","visual":"Bottom half returns: the capsule labelled 'cobalt 60' (YK.label 56) on cue l5 'cobalt'; tag 'isotope' (44) on cue 'isotope'; a violet gamma beam on cue 'gamma' passes through a thick steel plate on cue 'penetrating' + label 'high penetrating power' (48). Prereq chip YK.chip('Radioactivity and gamma rays', {kind:'prereq'}) ≤ 2 s.","tts_text":"والـ cobalt ستين، isotope بيطلّع gamma rays ليها penetrating power عالية.","screen_text":"Cobalt 60: gamma rays, high penetrating power"},{"id":"l6","visual":"Aha (hold ≥ 1.5 s, answers the hook): three uses top → bottom, each lit by the beam on its cue: a food crate (cue l6 'الأكل', label 'food preserving' 48), YK.icon 'pipe' with a hidden crack and weld seam glowing as the beam passes (cue 'الشروخ', label 'cracks and welds'), the body with the tumor spot dimming (cue 'tumors', label 'tumors'). Max 3 items (S7).","tts_text":"فبيحفظ الأكل، ويكشف الشروخ واللحام، ويعالج الـ tumors كمان.","screen_text":"Food preserving · cracks and welds · tumors"},{"id":"l7","style":"curious","visual":"Self-check on a NEW food (R8; third recorded misconception): a tray of strawberries on a conveyor passes the cobalt 60 beam; question in the band (Cairo 1000, 64, ≤ 2 lines) on cue l7 'gamma'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; checkPause would stamp its own ✓) through the stitched silence (trailing <long pause> stripped, pause_after_s 1.5).","tts_text":"طب فراولة عدّت عليها gamma rays من cobalt ستين… بقت radioactive؟ فكّروا. <long pause>","screen_text":"Strawberries treated with cobalt 60 gamma rays: radioactive?"},{"id":"l8","visual":"Answer: the strawberries move on, plain (no glow) + YK.rightMark on cue l8 'لأ'; rays shown passing through and leaving on 'بتعدّي'; label 'not radioactive' (48) on cue 'radioactive'.","tts_text":"لأ، الأشعة بتعدّي وتمشي، والأكل مبيبقاش radioactive خالص.","screen_text":"No: the rays pass through; the food is not radioactive"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Economic importance of iron and cobalt', line:'Cobalt 60 is used for its gamma rays.', formula:'H_2 + CO ->[Fe] fuel', t, pulse:[{word:'Cobalt 60', at:YK.cue('l9','cobalt')}, {word:'gamma rays', at:YK.cue('l9','gamma')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the split frame 0 (iron bed and fuel drop, cobalt beam and tumor).","tts_text":"الـ cobalt ستين بيتستخدم عشان الـ gamma rays بتاعته.","screen_text":"Cobalt 60 is used for its gamma rays."}],"logline":"Iron helps make fuel and cobalt treats tumours: iron is a catalyst that converts water gas (a mixture of hydrogen and carbon monoxide, not water vapour) into fuel by the Fischer-Tropsch method; cobalt 60 gives out gamma rays with high penetrating power, used in food preserving, detecting cracks and welds, and treating tumours, and the food does not become radioactive. New terms: water gas, Fischer-Tropsch, cobalt 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iron بتساعد نعمل fuel و cobalt بيعالج\ntumors إزاي\nوهنا الـ iron بيخلّي الـ water gas يتحوّل\nfuel بسرعة\nيعني catalyst بطريقة اسمها Fischer-Tropsch\nهنا\nوالـ water gas مش بخار مية ده hydrogen و\ncarbon monoxide متخلطين\nوالـ cobalt ستين isotope بيطلّع gamma rays\nليها penetrating power عالية\nفبيحفظ الأكل ويكشف الشروخ واللحام ويعالج\nالـ tumors كمان\nطب فراولة عدّت عليها gamma rays من cobalt\nستين بقت radioactive فكّروا\nلأ الأشعة بتعدّي وتمشي والأكل مبيبقاش\nradioactive خالص\nالـ cobalt ستين بيتستخدم عشان الـ gamma\nrays بتاعته","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":25},{"id":"chem-s3-en.video-short-te.uses-ni","kind":"short","version":1,"ord":111,"content_lang":"ar-EG","primary_concept_id":"te.uses-ni","concepts":[{"concept_id":"te.uses-ni","role":"primary"}],"title":"Economic importance of nickel","payload":{"title":"Economic importance of nickel","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): a hair-dryer cut-away (custom outline) at (540, 1000) with its coil already glowing red at t=0 (heat shimmer, pulsing). Hook in the band (Cairo 1000 ~100): 'Red hot daily.' / 'Lasts for years?'. The coil flares on cue l1 'بيحمرّ'.","tts_text":"سلك السشوار بيحمرّ كل يوم… وبيعيش سنين. إزاي؟","screen_text":"Red hot daily. Lasts for years?"},{"id":"l2","visual":"Zoom into the coil: label 'heating coil' (52) on cue l2 'heating'; on cue 'alloy' a YK.lattice (rows 5, cols 8, nickel grey) with chromium discs mixed in (`substitute` cells, color YK.atomColor('Cr')); label 'nickel–chromium alloy' (52) replaces 'heating coil' on cue 'nickel'; gloss 'alloy: a metal mixed with other elements' (40, textDim) under it on cue 'متخلطين'.","tts_text":"ده heating coil من alloy، يعني nickel و chromium متخلطين.","screen_text":"Heating coil: nickel–chromium alloy"},{"id":"l3","visual":"Myth beat (top recorded misconception, R11, G40): small coral card with a lightning glyph and 'good conductor' (48, 60% size) on cue l3 'conductor'; YK.wrongMark on cue 'مش', card exits.","tts_text":"ناس فاكرة إنه اتختار عشان conductor كويس… مش ده السبب.","screen_text":"Because it is a good conductor? ✕"},{"id":"l4","visual":"Aha (hold ≥ 1.5 s, answers the hook): the red-hot coil in air, YK.molecule 'O2' hitting it and bouncing off, the coil surface stays smooth and intact on cue l4 'corrosion' (no oxide-layer mechanism: not the book's reason here, R3) + label 'resists corrosion at high temperature' (52, mint, ≤ 2 lines) + YK.rightMark on cue 'الحرارة'.","tts_text":"السبب إنه بيقاوم الـ corrosion في الحرارة العالية.","screen_text":"Resists corrosion at high temperature ✓"},{"id":"l5","visual":"A nickel cube splits into a 6×6 grid of tiny cubes that scatter into a powder pile (custom, staggered by YK.rng) on cue l5 'finely' + label 'finely divided nickel' (52); the powder pile gets tag 'catalyst' (48, gold) on cue 'catalyst'. Prereq chip YK.chip('Catalyst', {kind:'prereq'}) ≤ 2 s.","tts_text":"والـ nickel الـ finely divided، يعني بودرة ناعمة، catalyst للزيوت.","screen_text":"Finely divided nickel: a catalyst"},{"id":"l6","visual":"On the powder surface (YK.surface({metal:'Ni', molecules:[{mol:'H2', …}]})): amber oil drops and H₂ molecules meet and join on cue YK.cue('l6','hydrogen',1) (needle 'hydrogen' hits 'hydrogenation' first); label 'hydrogenation of oils' (52) on cue 'hydrogenation'; the joining speeds up on 'أسرع'.","tts_text":"في الـ hydrogenation: بيخلّي الـ hydrogen يضاف للزيت أسرع.","screen_text":"Hydrogenation of oils"},{"id":"l7","style":"curious","visual":"Self-check on a NEW use (R8: the furnace is never shown): an electric furnace box (custom) with glowing coils inside, label 'electric furnace' (48) on cue l7 'electric'; question in the band (Cairo 1000, 64) on cue 'alloy'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; checkPause would stamp its own ✓) through the stitched silence (trailing <long pause> stripped, pause_after_s 1.5).","tts_text":"طب الـ electric furnace، الـ alloy بتاعه لازم يقاوم إيه؟ فكّروا. <long pause>","screen_text":"Electric furnace: what must its alloy resist?"},{"id":"l8","visual":"Answer: label 'corrosion at high temperature' (52) + YK.rightMark on cue l8 'corrosion'; the furnace coils take the gold outline of the l2 alloy lattice on cue 'alloy'.","tts_text":"الـ corrosion في الحرارة العالية، فبيستخدموا نفس الـ alloy ده.","screen_text":"Corrosion at high temperature: the same alloy"},{"id":"l9","visual":"Voiced lock-in (S3): YK.takeaway({title:'Economic importance of nickel', line:'Ni–Cr alloy: resists corrosion at high temperature.', t, pulse:[{word:'alloy', at:YK.cue('l9','alloy')}, {word:'corrosion', at:YK.cue('l9','corrosion')}]}) ≥ 2.5 s. Loop (S5): last 0.8 s the red-hot hair-dryer coil of frame 0.","tts_text":"الـ alloy ده بيقاوم الـ corrosion وهو سخن.","screen_text":"Ni–Cr alloy: resists corrosion at high temperature."}],"logline":"A hair-dryer coil glows red hot every day for years: heating coils are nickel-chromium alloy because it resists corrosion at high temperature (not because it conducts well); finely divided nickel is a catalyst in the hydrogenation of oils. New terms: finely divided, hydrogenation (alloy glossed; heating coil and electric furnace are 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السشوار بيحمر كل يوم وبيعيش سنين إزاي\nده heating coil من alloy يعني nickel و\nchromium متخلطين\nناس فاكرة إنه اتختار عشان conductor كويس\nمش ده السبب\nالسبب إنه بيقاوم الـ corrosion في الحرارة\nالعالية\nوالـ nickel الـ finely divided يعني بودرة\nناعمة catalyst للزيوت\nفي الـ hydrogenation بيخلّي الـ hydrogen\nيضاف للزيت أسرع\nطب الـ electric furnace الـ alloy بتاعه\nلازم يقاوم إيه فكّروا\nالـ corrosion في الحرارة العالية\nفبيستخدموا نفس الـ alloy ده\nالـ alloy ده بيقاوم الـ corrosion وهو سخن","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":26},{"id":"chem-s3-en.video-short-te.uses-cu-zn","kind":"short","version":1,"ord":113,"content_lang":"ar-EG","primary_concept_id":"te.uses-cu-zn","concepts":[{"concept_id":"te.uses-cu-zn","role":"primary"}],"title":"Economic importance of copper and zinc","payload":{"title":"Economic importance of copper and zinc","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (S13): an ancient Egyptian statuette silhouette (custom path, bronze gradient, slow turntable glint) at (540, 1000). Hook in the band at t=0 (Cairo 1000 ~110): 'Bronze alloy:' / 'copper + !{?}'. No separate 'bronze' label or 'copper + ?' tiles (the hook says both; G16): the statue glints on cue l1 'bronze'; gloss 'alloy: a metal mixed with other elements' (40, textDim) under the statue on cue 'alloy'; the hook's '?' pulses gold on cue 'copper' (YK.band accentAt).","tts_text":"تماثيل الفراعنة من الـ bronze، alloy يعني معادن متخلطة… copper مع إيه؟","screen_text":"Bronze alloy: copper + ?"},{"id":"l2","visual":"A horizontal timeline bar (x 140–940, y 1300) with a copper disc at its far left labelled 'copper' (48) on cue l2 'copper' and 'first discovered metal' (48, gold) on cue 'metal'.","tts_text":"والـ copper ده أول metal اتكشف أصلًا.","screen_text":"Copper: the first discovered metal"},{"id":"l3","visual":"Myth beat (top recorded misconception, R11, G40) and aha (hold ≥ 1.5 s, answers the hook): small coral 'copper + zinc' (48, 60% size) on cue l3 'zinc' + YK.wrongMark on cue 'لأ'; bigger tiles 'copper' + 'tin' slide together on cue 'tin' and merge into 'bronze' (56, gold); the statue glows + YK.rightMark.","tts_text":"ناس فاكرة copper و zinc… لأ، الـ bronze من copper و tin مع بعض.","screen_text":"Copper + zinc ✕   Copper + tin = bronze ✓"},{"id":"l4","visual":"YK.icon 'cable' with current dots flowing on cue l4 'conductor' + label 'good conductor of electricity' (48); label 'electric cables' (48) on cue 'cables'; YK.icon 'coin' + label 'coins' (48) on cue 'والعملات'.","tts_text":"والـ copper conductor كويس للكهربا، فبيتعمل منه الـ cables والعملات المعدن.","screen_text":"Good conductor of electricity → electric cables, coins"},{"id":"l5","visual":"An iron sheet dips into molten zinc and comes out with a grey coat on cue l5 'بيغلّف' (label 'zinc' 48 on cue 'zinc'); label 'galvanizing' (56, gold) on cue 'galvanizing'; rain drops bounce off, no rust + label 'protects from rusting' (48, mint) on cue 'rusting'. Prereq chip YK.chip('Rusting and corrosion', {kind:'prereq'}) ≤ 2 s.","tts_text":"والـ zinc بيغلّف الـ metals التانية، galvanizing، فالـ rusting ميوصلهاش.","screen_text":"Zinc: galvanizing other metals → protects them from rusting"},{"id":"l6","style":"curious","visual":"Self-check on a NEW object (R8): an iron fence (custom bars, label 'iron' 48 on cue l6 'iron') under rain; two choice chips 'copper' / 'zinc' (48) on their cues; question in the band (Cairo 1000, 64, ≤ 2 lines) on cue 'iron'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l6','فكّروا'), end: YK.cue('l7')}) (short.js; checkPause would stamp its own ✓) through the stitched silence (trailing <long pause> stripped, pause_after_s 1.5).","tts_text":"طب سور iron في المطر… نغلّفه بإيه، copper ولا zinc؟ فكّروا. <long pause>","screen_text":"Iron fence outdoors: coat it with copper or zinc?"},{"id":"l7","visual":"Answer: the 'zinc' chip lights + YK.rightMark on cue l7 'zinc'; the fence takes a grey zinc coat on cue 'galvanizing', rain bounces off, no rust on 'rusting'.","tts_text":"بالـ zinc، يعني galvanizing، عشان الـ rusting ميوصلوش.","screen_text":"Zinc: galvanizing protects it from rusting"},{"id":"l8","visual":"Voiced lock-in (S3): YK.takeaway({title:'Economic importance of copper and zinc', line:'Bronze: copper + tin. Zinc: galvanizing.', t, pulse:[{word:'Bronze', at:YK.cue('l8','bronze')}, {word:'tin', at:YK.cue('l8','tin')}, {word:'galvanizing', at:YK.cue('l8','galvanizing')}]}) ≥ 2.5 s (needs the l8 tts fix). Loop (S5): last 0.8 s the bronze statuette of frame 0.","tts_text":"الـ bronze copper و tin، والـ zinc للـ galvanizing عشان يحمي غيره.","screen_text":"Bronze: copper + tin. Zinc: galvanizing."}],"logline":"Ancient Egyptian statues are bronze, an alloy of copper and tin (not zinc); copper, the first discovered metal, is a good conductor of electricity for cables and coins; zinc protects other metals from rusting by galvanizing. New terms: bronze, galvanizing (alloy 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الفراعنة من الـ bronze alloy يعني\nمعادن متخلطة copper مع إيه\nوالـ copper ده أول metal اتكشف أصلًا\nناس فاكرة copper و zinc لأ الـ bronze من\ncopper و tin مع بعض\nوالـ copper conductor كويس للكهربا فبيتعمل\nمنه الـ cables والعملات المعدن\nوالـ zinc بيغلّف الـ metals التانية\ngalvanizing فالـ rusting ميوصلهاش\nطب سور iron في المطر نغلّفه بإيه copper\nولا zinc فكّروا\nبالـ zinc يعني galvanizing عشان الـ\nrusting ميوصلوش\nالـ bronze copper و tin والـ zinc للـ\ngalvanizing عشان يحمي غيره","countable":true,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":27},{"id":"chem-s3-en.video-short-atom.hund-rule","kind":"short","version":1,"ord":167,"content_lang":"ar-EG","primary_concept_id":"atom.hund-rule","concepts":[{"concept_id":"atom.hund-rule","role":"primary"}],"title":"Hund's rule and orbital-box diagrams","payload":{"title":"Hund's rule and orbital-box diagrams","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 is complete (S13): YK.electronBoxes(ctx, 540, 1050, {boxes:5, electrons:0, size:150, label:'d sublevel'}) (row 750 px, x 165-915; label 48 textDim) + six cyan electron dots drifting above it (y 780-880, YK.rng seed) + hook 'How?' line already on screen at t=0 in the headline band (x 108 left-aligned, Cairo 1000 ~100, 2 lines: '6 electrons. 5 empty orbitals.' / 'How?'). Signals, not entrances: the six dots flash on cue l1 'electrons', the five box rims flash on cue 'orbitals', 'How?' pulses gold on cue 'إزاي'. 2 text blocks (hook + label).","tts_text":"ستة electrons وخمس orbitals فاضيين… هيقعدوا إزاي؟","screen_text":"6 electrons. 5 empty orbitals. How?"},{"id":"l3","visual":"Headline 'Singly first' (72) on cue l3 'singly'. From that cue, dots 1→5 fly on arcs (YK.flyer, 0.5 s each, staggered 0.3 s, done ≈ 1.7 s later, G23) into boxes 1→5; when each lands, electronBoxes `electrons` goes ['↑','',…] → ['↑','↑','↑','↑','↑'] (all cyan ↑, same direction: parallel shown, named in l6). On cue 'repel': small double-headed arrows (YK.arrow both ways, textDim) pulse between neighbouring electrons, label 'repel' (48) above the row. The 6th dot keeps hovering above. screen_text = headline + 'repel' label.","tts_text":"أول خمسة بيدخلوا singly، عشان الـ electrons بتعمل repel لبعض.","screen_text":"Singly first: electrons repel"},{"id":"l5","visual":"Headline 'Singly first' and 'repel' fade out at line start; headline '6th electron: pairing starts' (72) in. Prereq chip YK.chip(ctx, 540, 600, 'Electron spin and the Pauli principle', {kind:'prereq', align:'center'}) at line start for ≤ 2 s (S6; moved from the cut reminder line). The 6th dot scans the row right→left above the boxes (box rims flash gold one by one, 0.15 s each, no text) on cue l5 'فاضي', and on cue 'pairing' arcs (YK.flyer) into box 1, landing as a pink ↓ on cue 'لتحت' → box 1 = ↑↓ (opposite spins); tag 'paired' (48) above box 1. Row now ↑↓ ↑ ↑ ↑ ↑.","tts_text":"الـ electron السادس ملقاش orbital فاضي، فيعمل pairing، والـ spin بتاعه لتحت.","screen_text":"6th electron: pairing starts"},{"id":"l6","visual":"The short's one definition card (G16/S7b): YK.termCard(ctx, 108, 600, {align:'left', term:\"Hund's rule\", def:'Electrons occupy the orbitals of the same sublevel singly, with parallel spins, before pairing starts.', keys:['singly','parallel spins','pairing']}) on cue l6 \"Hund's\" (new term 2; wording = lesson-atom.hund-rule key term; the chapter only names the rule, Ch.1 p.8 point 1). At the same cue the row (↑↓ ↑ ↑ ↑ ↑) slides down to y ≈ 1480 and dims to 35% (G17), so the card sits on clean background. On cue 'parallel' the five ↑ of the dimmed row flash cyan together; on cue 'pairing' the gold word 'pairing' pulses and box 1 of the dimmed row flashes.","tts_text":"ودي Hund's rule: singly و parallel spins الأول، والـ pairing بعدين.","screen_text":"Hund's rule: Electrons occupy the orbitals of the same sublevel singly, with parallel spins, before pairing starts."},{"id":"l7","visual":"Myth beat (R11, G40). Correct row (↑↓ ↑ ↑ ↑ ↑, size 150) back at y 1150, 35% while the myth shows. From cue l7 'pairing': a smaller wrong strip YK.electronBoxes(ctx, 540, 720, {size:90, electrons:['↑↓','↑↓','↑↓','',''], colors:{box:coral}}) (450 px, 60% of the right one) with label 'Pairing first' (48, coral); YK.wrongMark beside it on cue 'غلط'; its two empty boxes pulse on cue 'فاضية'; it exits 0.4 s later (shorter and smaller than the right one). On cue 'singly' the correct row returns to 100% with label 'Singly first' (48, mint) and YK.rightMark (mint). ✕/✓ are the kit stamps, never typed glyphs.","tts_text":"ناس كتير بتعمل pairing وفيه orbitals لسه فاضية… غلط، singly الأول.","screen_text":"Pairing first ✕   Singly first ✓"},{"id":"l8","visual":"Aha (hold ≥ 1.5 s): headline band shows YK.formula 'd^6' (mono, 110) at line start. On cue l8 'pair' box 1 (↑↓) and its 'paired' tag pulse, then dim to 60%. On cue 'unpaired' the four lone ↑ glow gold (highlight [1,2,3,4] + YK.glow) and under the row: big gold '4' + 'unpaired electrons' (56) (new term 3). Answers the l1 hook.","tts_text":"يبقى الستة: pair واحد، وأربعة unpaired electrons قاعدين لوحدهم.","screen_text":"d⁶: 4 unpaired electrons"},{"id":"l9","style":"curious","visual":"Self-check on a new case (R8): row empties (size 150, y 1050); eight cyan dots hover above it. Question 'd⁸: how many unpaired electrons?' in the headline band (Cairo 900, 72, maxWidth 864, ≤ 2 lines) on cue l9 'تمانية'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l9','فكّروا'), dur: YK.cue('l10') - YK.cue('l9','فكّروا'), question:'', answer:''}) runs through the ≥ 1 s silence (<long pause>; if the take trims it, the narrator widens the l9→l10 gap to ≥ 1 s).","tts_text":"طب لو تمانية electrons؟ كام واحد هيفضل unpaired؟ فكّروا ثانية. <long pause>","screen_text":"d⁸: how many unpaired electrons?"},{"id":"l10","visual":"Answer: on cue l10 'اتنين' the question is replaced by '2 unpaired' (headline, gold '2') + YK.rightMark. On cue 'خمسة' dots 1-5 drop in singly (cyan ↑, YK.flyer, 0.25 s stagger); on cue 'تلاتة' three dots land as pink ↓ in boxes 1-3 → ↑↓ ↑↓ ↑↓ ↑ ↑; label '5 singly + 3 pairs' (48) under the row on cue 'pairs'; the last two ↑ glow gold. Lock-in and loop: l11.","tts_text":"اتنين unpaired بس: خمسة دخلوا singly، وتلاتة عملوا pairs معاهم.","screen_text":"2 unpaired: 5 singly + 3 pairs"},{"id":"l11","visual":"Voiced lock-in (S3): YK.takeaway({title:\"Hund's rule and orbital-box diagrams\", line:'Singly first, then pairing.'}) from cue l11 start, held through the line + tail (≥ 2.5 s); the d⁸ row (↑↓ ↑↓ ↑↓ ↑ ↑) stays dimmed 35% behind it. Signals: 'Singly' pulses gold on cue 'singly', 'pairing' on cue 'pairing'. Loop (S5): in the last 0.8 s the card exits and the five-box row is alone at (540, 1050), size 150, as in frame 0, now filled.","tts_text":"الخلاصة: singly الأول، والـ pairing بعدين.","screen_text":"Singly first, then pairing."}],"logline":"Six electrons, five empty d orbitals: they go in singly with parallel spins first, and only the sixth pairs up, so d⁶ has 4 unpaired 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electrons وخمس orbitals فاضيين هيقعدوا\nإزاي\nأول خمسة بيدخلوا singly عشان الـ electrons\nبتعمل repel لبعض\nالـ electron السادس ملقاش orbital فاضي\nفيعمل pairing والـ spin بتاعه لتحت\nودي Hund's rule singly و parallel spins\nالأول والـ pairing بعدين\nناس كتير بتعمل pairing وفيه orbitals لسه\nفاضية غلط singly الأول\nيبقى الستة pair واحد وأربعة unpaired\nelectrons قاعدين لوحدهم\nطب لو تمانية electrons كام واحد هيفضل\nunpaired فكّروا ثانية\nاتنين unpaired بس خمسة دخلوا singly وتلاتة\nعملوا pairs معاهم\nالخلاصة singly الأول والـ pairing بعدين","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":9},{"id":"chem-s3-en.video-short-te.electron-configuration","kind":"short","version":1,"ord":169,"content_lang":"ar-EG","primary_concept_id":"te.electron-configuration","concepts":[{"concept_id":"te.electron-configuration","role":"primary"}],"title":"Electronic configuration of the first transition series","payload":{"title":"Electronic configuration of the first transition series","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 is complete (S13): YK.dBlockZoom at p=1 (strip only, 2 rows Sc-Mn over Fe-Zn, stripY 1050, violet d-block tiles, all ten drawn as transition elements, G44) + one cyan electron hopping tile to tile left→right (YK.flyer arcs, 0.25 s per hop, loops) + hook already on screen at t=0 in the headline band (x 108, Cairo 1000 ~100, 2 lines: 'Sc → Zn: one more electron.' / 'Where?'). Signals: Sc tile glows + label 'Scandium' (48) under it on cue l1 'scandium'; Zn tile glows + 'Zinc' on cue 'zinc'; 'Where?' pulses gold on cue 'فين'. Book Ch.1 p.5: series ₂₁Sc → ₃₀Zn.","tts_text":"من الـ scandium لحد الـ zinc، كل عنصر بيزوّد electron واحد… بيروح فين؟","screen_text":"Sc → Zn: one more electron. Where?"},{"id":"l3","visual":"Push in (YK.camera, 0.8 s) at line start from the l1 strip to YK.configStrip(ctx, 540, 1050, {Z:30, step:2, size:100, label:'none'}) (Ca state: 4s ↑↓, five empty 3d boxes). Prereq chip 'Writing electron configurations' (kind prereq, y 600, ≤ 2 s, S6; moved from the cut Ca line) at line start. Headline formula '_{21}Sc' (mono 110) on cue l3 'scandium'. Step 2 → 3 on cue 'three' (one cyan ↑ arcs into 3d box 1, kit arrival arc); the live label turns on (label:'below') and reads '[Ar] 4s^2 3d^1'; the '3d' sub-label gets a gold underline on cue 'three'. Book table p.8: ₂₁Sc [Ar] 4s² 3d¹.","tts_text":"في الـ scandium، الجديد بيدخل الـ three d على طول.","screen_text":"₂₁Sc: [Ar] 4s² 3d¹"},{"id":"l4","visual":"On cue l4 'manganese' (first word) the goal appears: headline '_{25}Mn' ghosted at 40%. Prereq chip \"Hund's rule and orbital-box diagrams\" (y 600, ≤ 2 s) on cue 'orbital'. step 3 → 7 from cue 'orbital' to cue 'لوحده' (cyan ↑ arcs into 3d boxes 2-5 singly); headline ticker follows step: _{22}Ti, _{23}V, blank at step 6 (3d⁴: Cr does not follow this pattern, handled in l6), then '_{25}Mn' solid at 100% at step 7. Live label ends '[Ar] 4s^2 3d^5'. Book p.8 point 1: single electron in each orbital till manganese (3d⁵).","tts_text":"ولحد الـ manganese، كل orbital ياخد electron واحد بس، لوحده.","screen_text":"₂₅Mn: [Ar] 4s² 3d⁵"},{"id":"l5","visual":"On cue l5 'pairing': label 'pairing' (48, pink) above the 3d boxes; step 7 → 12 from that cue to cue 'بعشرة' (pink ↓ arc into 3d boxes 1→5). Ticker: _{26}Fe, _{27}Co, _{28}Ni, blank at step 11 (3d⁹: Cu, handled in l6), '_{30}Zn' on step 12 (≈ cue 'zinc'). Live label ends '[Ar] 4s^2 3d^10'. Book p.8 point 1: after manganese pairing of electrons takes place in each orbital till zinc (3d¹⁰) (Hund's rule).","tts_text":"وبعده يبدأ الـ pairing، لحد الـ zinc بعشرة.","screen_text":"₃₀Zn: [Ar] 4s² 3d¹⁰"},{"id":"l6","visual":"Aha (hold ≥ 1.5 s). At line start: strip label:'none' and in its place YK.formula '[Ar] 4s^2 3d^!{n}' (mono 64; the '10' cross-fades to the gold 'n'), the 3d boxes glow violet. On cue l6 'four' the 4s ↑↓ box pulses mint (it stays). On cue 'chromium' Cr outline flashes, on cue 'copper' Cu; on cue 'anomalous': the Zn strip dims to 35% (G17) and the small Sc→Zn strip (dBlockZoom p=1, stripW 700, stripY ≈ 700) slides in at the top of the stage with Cr and Cu outlined gold and the label 'Cr, Cu anomalous' (56) beside/under it. Book p.8 point 2: Chromium and copper are anomalous. No Cr/Cu configuration is taught here.","tts_text":"والـ four s ثابتة… إلا الـ chromium والـ copper، دول anomalous.","screen_text":"[Ar] 4s² 3dⁿ · Cr, Cu anomalous"},{"id":"l7","visual":"Myth beat (concept misconception 1, R11, G40). Headline YK.formula '_{26}Fe' on cue l7 'iron'. Small wrong row first: YK.electronBoxes(ctx, 540, 720, {size:80, electrons:['↑↓','↑↓','↑↓','',''], colors:{box:coral}, label:'3d'}) (≈ 60% size) with label '3 pairs' (48, coral) on cue 'pairs' and YK.wrongMark on cue 'غلط'; it exits 0.4 s later. Then the big Fe strip configStrip(Z:26, size 100, y 1150, label '[Ar] 4s^2 3d^6') ↑↓ ↑ ↑ ↑ ↑ with YK.rightMark (mint) on cue 'singly' and unpaired: 0→1 on cue 'unpaired' (kit gold glow + 'unpaired = 4' tag). The right strip is on screen longer and bigger than the wrong one.","tts_text":"ناس بترسم الـ iron تلات pairs… غلط، singly الأول، فأربعة unpaired.","screen_text":"₂₆Fe 3d⁶: 3 pairs ✕   unpaired = 4 ✓"},{"id":"l8","style":"curious","visual":"Self-check on a new case (R8; lesson worked example is Fe, its exercise Co): empty configStrip(Z:28, step:0, size 100, y 1050, label:'none'), headline formula '_{28}Ni' on cue l8 'nickel'; check question 'Write the electron configuration of ₂₈Ni.' (Cairo 900, 72, ≤ 2 lines) in the headline band under it on cue 'configuration'. YK.checkPause(ctx, 540, 1520, {t, start: YK.cue('l8','فكّروا'), dur: YK.cue('l9') - that start, question:'', answer:''}) through the ≥ 1 s silence (<long pause>; if the take trims it, the narrator widens the l8→l9 gap to ≥ 1 s).","tts_text":"اكتبوا الـ electron configuration بتاع الـ nickel… فكّروا. <long pause>","screen_text":"Write the electron configuration of ₂₈Ni."},{"id":"l9","visual":"Answer: step 0→2 on cue l9 'four' (4s ↑↓), 2→10 from cue 'three' over 1.2 s (3d ↑↓ ↑↓ ↑↓ ↑ ↑); label:'below' turns on at cue 'three' and ends '[Ar] 4s^2 3d^8' (book table p.8); YK.rightMark + unpaired: 0→1 ('unpaired = 2') on cue 'unpaired'. Lock-in and loop: l10.","tts_text":"argon، four s two، three d eight… واتنين unpaired بس.","screen_text":"₂₈Ni: [Ar] 4s² 3d⁸ · unpaired = 2"},{"id":"l10","visual":"Voiced lock-in (S3): YK.takeaway({title:'Electronic configuration of the first transition series', line:'Singly up to Mn, then pairing', formula:'[Ar] 4s^2 3d^n'}) from cue l10 start, held through the line + tail (≥ 2.5 s); Ni strip dimmed 35% behind it. Signals: 'Singly' + 'Mn' pulse gold on cues 'singly'/'manganese', 'pairing' on 'pairing'; the formula's 4s² pulses mint with the pairing cue. Book p.8 point 1. Loop (S5): the last 0.8 s returns to the l1 Sc→Zn strip (stripY 1050) with the electron hopping.","tts_text":"singly لحد الـ manganese، والـ pairing بعده.","screen_text":"Singly up to Mn, then pairing · [Ar] 4s² 3dⁿ"}],"logline":"From Sc to Zn each element adds one electron: it goes into 3d, singly up to Mn (3d⁵), then pairing till Zn (3d¹⁰), while 4s² stays; Cr and Cu are 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copper","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete: YK.band at 0 '_{24}Cr: 4s^2 3d^4 !{?}' (Cairo 1000, 110; '?' accentAt YK.cue('l1','صح')). Stage: YK.configStrip(ctx, 540, 1050, {el:'Cr', size:100, anomaly:0, stable:0, label:'none'}) = the EXPECTED 4s ↑↓ + 3d ↑ ↑ ↑ ↑ _ (anomaly:0 keeps the hop electron in 4s); the empty 5th 3d box YK.flashRect gold pulsing (1.2 s loop) from frame 0; 4s box flashes on cue 'four', 3d boxes on cue 'three'. Live label OFF here (the band carries the config; no duplicate text). Prereq chip 'Electronic configuration of the first transition series' from line start, <= 2 s. Book p.8 point 1. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"المفروض الـ chromium يبقى four s اتنين، three d أربعة… صح؟","screen_text":"₂₄Cr: 4s² 3d⁴ ?"},{"id":"l2","visual":"Aha: on cue 'four' anomaly 0→1 over 0.8 s (the 2nd 4s electron hops on an arc into the empty 3d box, kit flyer trail); keep stable:0 (the badge belongs to l3). Live label (label:'below') fades in on cue 'three' reading '[Ar] 4s^1 3d^5' (book table p.8). Band → 'The book says !{why}?' on cue 'ليه' (no second copy of the config in the band).","tts_text":"لأ، الكتاب كاتبه four s واحد، three d خمسة… ليه؟","screen_text":"₂₄Cr: [Ar] 4s¹ 3d⁵"},{"id":"l3","visual":"On cue 'half-filled': configStrip stable 0→1 with stableText:'half filled' (the kit's mint frame + chip over the five 3d boxes = the bracket). On cue 'orbital' each 3d box YK.flashRect mint L→R, 0.12 s apart (one ↑ per orbital). New term 1. No other text.","tts_text":"الـ three d بقت half-filled: كل orbital فيه electron واحد.","screen_text":"3d⁵: half filled"},{"id":"l4","visual":"YK.label '3d^5 -> !{extra stability}' (56, y 1380, centred) on cue 'extra'; on cue 'بتقل' a mint YK.arrow pointing down beside the strip (x 960 → inside 972; no text). Footnote YK.text 'Not the only factor' (40, textDim, y 1480) fades in at line end (book p.9 hedge, no 'Book p.9' on screen). New term 2.","tts_text":"يعني extra stability: طاقة الـ atom بتقل.","screen_text":"3d⁵ → extra stability"},{"id":"l5","visual":"Cr strip slides up to y 760 and dims (dim:1). YK.configStrip(ctx, 540, 1200, {el:'Cu', size:100, anomaly: prog(cue 'copper', +0.8), stable:0, label:'below'}): anomaly 0 draws 4s² 3d⁹ (last 3d box half empty), the hop fills it; live label reads '[Ar] 4s^1 3d^10' and flashes on cue 'three'; on cue 'filled' stable 0→1 with stableText:'filled'. Two configurations on screen = S3b max. Book p.8 point 2 / p.9. New term 3.","tts_text":"والـ copper نفس الفكرة: three d عشرة، filled بالكامل.","screen_text":"₂₉Cu: [Ar] 4s¹ 3d¹⁰ · filled"},{"id":"l6","visual":"Both strips exit (0.3 s). Myth (concept misconception 2, G40), small and short: coral wrong row at y 700 drawn with YK.electronBoxes (configStrip cannot draw a non-book config): 4s {boxes:1, electrons:['↑'], size:80, label:'4s'} + 3d {boxes:5, electrons:['↑↓','↑↓','↑','↑','↑'], size:80, label:'3d'}, YK.label 'Fe: 4s^1 3d^7' (48, coral) on cue 'iron'; YK.wrongMark on cue 'غلط'; the row exits 0.4 s later. Then the RIGHT version, bigger and longer: YK.dBlockZoom(ctx, 108, 600, 864, {p:1, stripY:1150, highlight:['Cr','Cu'], hlP}) (2 rows: Sc–Mn over Fe–Zn), Cr tile gold on cue 'chromium', Cu on cue 'copper' + ONE YK.rightMark; YK.cueLabel 'Only Cr and Cu (first series)' (52) on cue 'بس'.","tts_text":"ناس بتعملها في الـ iron… غلط، الـ chromium والـ copper بس.","screen_text":"Fe: 4s¹ 3d⁷ ✕   Only Cr, Cu ✓"},{"id":"l7","style":"curious","visual":"Prediction check, QUESTION ONLY (no answer on screen anywhere in l7 or its pause). New case: gold (book p.10 coinage metals; lesson used silver). Strip clears. On cue 'gold': YK.band 'Au: 6s^2 5d^9 !{?}' (expected, like l1 for Cr) + stage, book-order LTR as in l1: 6s YK.electronBoxes(ctx, 300, 1050, {label:'6s', boxes:1, electrons:['↑↓'], size:100}) and 5d YK.electronBoxes(ctx, 640, 1050, {label:'5d', boxes:5, electrons:['↑↓','↑↓','↑↓','↑↓','↑'], size:100}); the half-empty 5th 5d box YK.flashRect gold pulsing (1.2 s loop, mirrors l1's empty box). 6s box flashes on cue 'six', 5d boxes on cue 'five'. Band -> 'What will !{Au} do?' on cue 'هيعمل'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 1.5). During the pause the frame holds only: band question + expected boxes + pulsing gap + ring. No hop, no 6s^1/5d^10, no 'filled', no stamp before l8.","tts_text":"الـ gold متوقع six s اتنين، five d تسعة… هيعمل إيه؟ فكّروا. <long pause>","screen_text":"Au: 6s² 5d⁹ ?  What will it do?"},{"id":"l8","visual":"Reveal. On cue 'copper': a dimmed Cu strip (YK.configStrip(ctx, 540, 1380, {el:'Cu', size:80, dim:1, label:'none'})) ghosts in below to pair the two (Cu already did this in l5). On cue 'five': the 2nd 6s electron hops into the empty 5d box over 0.8 s (YK.flyer quadratic arc 6s box -> 5th 5d box, cyan trail; 6s electrons ['↑↓']->['↑'], 5d 5th box ['↑']->['↑↓'] when the flyer lands); gold pulse stops. On cue 'عشرة' (alt 'ten'): band -> 'Au: 6s^1 5d^{!{10}}'. On cue 'filled': YK.flashRect mint around the five 5d boxes + YK.cueLabel 'filled (d^{10})' (56, mint) above them + ONE YK.rightMark at x 900. Two configurations on screen max (S3b).","tts_text":"زي الـ copper: بقت five d عشرة، filled بالكامل.","screen_text":"Au: 6s¹ 5d¹⁰ filled, like Cu ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Abnormal electronic configuration of chromium and copper', line:'Half filled (d⁵) or filled (d¹⁰): more stable atom', formula:'Cr: [Ar] 4s^1 3d^5 · Cu: [Ar] 4s^1 3d^10', t, pulse:[{word:'Half', at:YK.cue('l9','half-filled')},{word:'stable', at:YK.cue('l9','أثبت')}]}) held >= 2.5 s (needle 'filled' would hit 'half-filled' first: do not pulse it). Loop (S5): last 0.8 s returns to the l1 Cr strip (expected 4s² 3d⁴, empty box pulsing).","tts_text":"السر: half-filled أو filled، يعني الـ atom أثبت.","screen_text":"Half filled (d⁵) or filled (d¹⁰): more stable atom"}],"logline":"The pattern predicts Cr 4s² 3d⁴, but the book writes [Ar] 4s¹ 3d⁵ (and Cu [Ar] 4s¹ 3d¹⁰): a half-filled d⁵ or filled d¹⁰ sublevel gives the atom lower energy, extra stability; only Cr and Cu do it in this 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complete: YK.band at 0 'Fe^{!{2+}}: what does 2+ mean?' (Cairo 1000, 96; accentAt cue 'two'). Stage: YK.label 'Fe^{!{2+}}' (mono 220, centre 540, 1000) with a slow scale pulse from frame 0; YK.glowCircle (gold) around the '2+' on cue 'two'. Prereq chip 'Main energy levels' at line end, <= 2 s. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"هتشوف كتير الـ iron وفوقه two plus… دي معناها إيه؟","screen_text":"Fe²⁺: what does 2+ mean?"},{"id":"l2","visual":"The big label shrinks into YK.atomDisc(ctx, 540, 980, 160, {el:'Fe'}) with 26 cyan YK.dot electrons placed by YK.swarm around it (minR outside the disc; deterministic). Two counters under it, protons LEFT / electrons RIGHT (y 1330, YK.label mono 64): '26 p^+' (coral, YK.counter 0→26) on cue 'proton', '26 e^-' (cyan) on cue 'electron'; YK.label '+26 − 26 = 0' (mono 56, mint, y 1440) on cue 'فمتعادلة'. Book: ₂₆Fe.","tts_text":"ذرة الـ iron فيها ستة وعشرين proton، وستة وعشرين electron، فمتعادلة.","screen_text":"Fe: 26 protons, 26 electrons"},{"id":"l3","visual":"On cue 'خسر' two of the dots fly off up-right with trails (G23) and the electron counter tweens 26→24; on cue 'ion' the disc's badge (atomDisc charge:'2+') pops and YK.cueLabel 'ion' (56) appears under the disc. New term 1.","tts_text":"لو خسر اتنين electrons، يبقى ion شحنته اتنين موجب.","screen_text":"Loses 2 electrons → Fe²⁺ ion"},{"id":"l4","visual":"On cue 'protons' the '26 p^+' counter gets a mint YK.flashRect (locked) + YK.cueLabel 'still iron (Fe)' (48) under it; on cue 'electrons' the two lost dots blink once at the top-right. Counters stay side by side (protons left, electrons right).","tts_text":"الـ protons ثابتة، فلسه iron… اللي بيتحرك الـ electrons بس.","screen_text":"Protons stay. Only electrons move."},{"id":"l5","visual":"YK.cueLabel 'cation' (64, gold) slides in above the Fe²⁺ disc on cue 'cation'; YK.label '2 lost -> 2+' (mono 56) under the counters on cue 'electrons'. New term 2.","tts_text":"الموجب اسمه cation: شحنته قد الـ electrons اللي خسرها.","screen_text":"Cation: positive, electrons lost"},{"id":"l6","visual":"The Fe²⁺ group slides to x 300 at 70%. YK.atomDisc 'Cl' (r 120) at x 780, y 1000 on cue 'chlorine'; one cyan YK.dot flies IN on cue 'electron'; badge '−' and label 'Cl^-' + YK.cueLabel 'anion' (64, cyan) on cue 'anion'. New term 3 (>= 1 s after 'cation').","tts_text":"والـ chlorine بيكسب electron، فيبقى anion سالب.","screen_text":"Cl + 1 electron → Cl⁻ anion"},{"id":"l7","style":"curious","visual":"New-case check (lesson used Fe, Na, Cl, O, Cu, Mn). Stage clears. YK.atomDisc 'Zn' (r 150, y 1000) on cue 'zinc'; YK.label '30 e^-' (mono 64, y 1300) on cue 'electron'; on cue 'خسر' two dots leave up-right and the counter becomes '? e^-' (gold). YK.band 'Zn^{2+} (Z = 30): how many electrons?' on cue 'zinc'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"الـ zinc فيه تلاتين electron، ولو خسر اتنين… فاضل كام؟ فكّروا. <long pause>","screen_text":"Zn²⁺ (Z = 30): how many electrons?"},{"id":"l8","visual":"Answer: '? e^-' → '28 e^-' on cue 'electron' + ONE YK.rightMark; '30 p^+' (coral) with a mint lock flash on cue 'protons'.","tts_text":"تمانية وعشرين electron بس، والـ protons لسه تلاتين.","screen_text":"Zn²⁺: 28 electrons, 30 protons"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Ions (cations and anions)', line:'Lose → cation (+) · Gain → anion (−)', formula:'Fe^2+ · Cl^-', t, pulse:[{word:'cation', at:YK.cue('l9','cation')},{word:'anion', at:YK.cue('l9','anion')}]}) >= 2.5 s. Loop: last 0.8 s back to the big 'Fe^2+' with the glowing '2+'.","tts_text":"اللي يخسر cation موجب، واللي يكسب anion سالب.","screen_text":"Lose → cation (+) · Gain → anion (−)"}],"logline":"Fe²⁺ means an iron atom that lost two electrons: protons stay, only electrons move; losing makes a cation (+), gaining makes an anion (−), and the charge counts the electrons lost or 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كتير الـ iron وفوقه two plus دي\nمعناها إيه\nذرة الـ iron فيها ستة وعشرين proton وستة\nوعشرين electron فمتعادلة\nلو خسر اتنين electrons يبقى ion شحنته\nاتنين موجب\nالـ protons ثابتة فلسه iron اللي بيتحرك\nالـ electrons بس\nالموجب اسمه cation شحنته قد الـ electrons\nاللي خسرها\nوالـ chlorine بيكسب electron فيبقى anion\nسالب\nالـ zinc فيه تلاتين electron ولو خسر اتنين\nفاضل كام فكّروا\nتمانية وعشرين electron بس والـ protons لسه\nتلاتين\nاللي يخسر cation موجب واللي يكسب anion\nسالب","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":12},{"id":"chem-s3-en.video-short-te.ion-configuration","kind":"short","version":1,"ord":175,"content_lang":"ar-EG","primary_concept_id":"te.ion-configuration","concepts":[{"concept_id":"te.ion-configuration","role":"primary"}],"title":"Ions: 4s electrons are lost first","payload":{"title":"Ions: 4s electrons are lost first","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete: YK.band at 0 'Fe → Fe^{2+}: !{4s or 3d} first?' (Cairo 1000, 96). Stage: YK.configStrip(ctx, 540, 1050, {el:'Fe', size:100, label:'below'}) ('[Ar] 4s^2 3d^6') with two gold '?' ghost dots hovering alternately over the 4s box and the 3d boxes (1.2 s cycle, from frame 0); 4s box YK.flashRect on cue 'four', 3d boxes on cue 'three'. ONE prereq chip here: 'Ions (cations and anions)' on cue 'هيخسر', <= 2 s (the configuration chip moves to l4). [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"الـ iron هيخسر اتنين: من four s ولا three d الأول؟","screen_text":"Fe → Fe²⁺: 4s or 3d first?"},{"id":"l2","visual":"Myth (concept misconception 1, R11/G40): the big Fe strip dims 35%, untouched. A STATIC coral wrong result at y 720 (no electrons animated leaving 3d: animating the wrong removal reinforces it, R11 = 0): YK.electronBoxes 4s {boxes:1, electrons:['↑↓'], size:80} + 3d {boxes:5, electrons:['↑','↑','↑','↑',''], size:80} with YK.label 'Fe^{2+} = [Ar] 4s^2 3d^4' (48, coral) on cue 'three'; YK.wrongMark on cue 'غلط'; the row exits 0.4 s later.","tts_text":"ناس بتشيل من الـ three d، عشان اتملت الآخر… غلط.","screen_text":"Fe²⁺ = [Ar] 4s² 3d⁴ ✕"},{"id":"l3","visual":"Guardrail S7a wording. Left of stage under the strip: two concentric rings (r 110 / 160, centre x 300, y 1400) labelled 'n = 3' (3d) and 'n = 4' (4s); on cue 'outer' the n = 4 ring glows gold + YK.cueLabel 'outer level' (48) and a YK.arrow links it to the 4s box. No energy-order claim anywhere (never '4s lower in energy').","tts_text":"عشان الـ four s في الـ outer level، فبتطلع الأول.","screen_text":"4s is the outer level: lost first"},{"id":"l4","visual":"configStrip({el:'Fe', charge:2, remove: prog(cue 'iron', +1.0), tag:true}): the two 4s electrons fly up-right with trails; tag 'Fe^2+'; live label '[Ar] 3d^6' flashes on cue 'three'; the empty 4s box YK.flashRect mint + ONE YK.rightMark on cue 'فاضية'. Prereq chip 'Electronic configuration of the first transition series' on cue 'argon', <= 2 s. Book p.9: Fe²⁺ [Ar] 3d⁶.","tts_text":"فالـ iron two plus يبقى argon و three d ستة، والـ four s فاضية.","screen_text":"Fe²⁺: [Ar] 3d⁶ ✓"},{"id":"l5","visual":"charge 3 with remove = lerp(2/3, 1, prog(cue 'three', +0.8)) so only the 3rd electron moves (the paired ↓ in box 1 leaves); tag 'Fe^3+', live label '[Ar] 3d^5'. YK.cueLabel '3d: one by one' (52) on cue 'واحد'. Book p.9 point 3.","tts_text":"ولو خسر أكتر، بيشيل من الـ three d واحد واحد.","screen_text":"Then 3d, one by one"},{"id":"l6","style":"curious","visual":"New-case check (lesson worked Fe²⁺/Co²⁺/Ni²⁺/Cr³⁺; Co³⁺ is new). Fe strip exits; fresh configStrip({el:'Co', size:100, label:'below', tag:true}) on cue 'cobalt' ('[Ar] 4s^2 3d^7'); YK.band 'Co^{3+} = ?' (mono 110) on cue 'cobalt'. 'three' is spoken twice (cobalt three / three d): cue the 3d boxes with YK.cue('l6','three',1). YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l6'), end: YK.cue('l7')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"والـ cobalt three plus؟ الـ atom four s اتنين، three d سبعة… آخره إيه؟ <long pause>","screen_text":"₂₇Co: [Ar] 4s² 3d⁷ → Co³⁺ = ?"},{"id":"l7","visual":"Answer: configStrip charge:3, remove: prog(cue 'argon', +1.2): both 4s electrons leave first, then one 3d (box 1 ↓); live label '[Ar] 3d^6' flashes on cue 'three'; the empty 4s box pulses mint on cue 'four'; ONE YK.rightMark.","tts_text":"يبقى argon و three d ستة… الـ four s فضيت الأول.","screen_text":"Co³⁺: [Ar] 3d⁶"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'Ions: 4s electrons are lost first', line:'4s first, then 3d', formula:'Fe^2+: [Ar] 3d^6', t, pulse:[{word:'4s', at:YK.cue('l8','four')},{word:'3d', at:YK.cue('l8','three')}]}) >= 2.5 s. Loop: last 0.8 s back to the full Fe strip with the two '?' ghost arrows.","tts_text":"الـ four s الأول، والـ three d بعدها.","screen_text":"4s first, then 3d"}],"logline":"Fe → Fe²⁺ loses its two 4s electrons, not 3d ones: 4s is the outer level, so it empties first ([Ar] 3d⁶); higher charges then take 3d electrons one by 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iron هيخسر اتنين من four s ولا three d\nالأول\nناس بتشيل من الـ three d عشان اتملت الآخر\nغلط\nعشان الـ four s في الـ outer level فبتطلع\nالأول\nفالـ iron two plus يبقى argon و three d\nستة والـ four s فاضية\nولو خسر أكتر بيشيل من الـ three d واحد\nواحد\nوالـ cobalt three plus الـ atom four s\nاتنين three d سبعة آخره إيه\nيبقى argon و three d ستة الـ four s فضيت\nالأول\nالـ four s الأول والـ three d بعدها","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":13},{"id":"chem-s3-en.video-short-pt.oxidation-number","kind":"short","version":1,"ord":177,"content_lang":"ar-EG","primary_concept_id":"pt.oxidation-number","concepts":[{"concept_id":"pt.oxidation-number","role":"primary"}],"title":"Oxidation state in compounds","payload":{"title":"Oxidation state in compounds","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete: YK.band at 0 'Fe_2O_3: iron (!{III}) oxide. Why III?' (Cairo 1000, 90; accentAt cue 'three'). Stage: five YK.atomDisc tokens in a row at y 1050 (formula order LTR: 2 'Fe' r 80, 3 'O' r 64, YK.atomColor), gentle bob from frame 0 (YK.molecule has no Fe2O3); YK.label 'Fe_2O_3' (mono 120) at y 820. Prereq chip 'Ions (cations and anions)', <= 2 s. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"الـ oxide ده فيه اتنين iron وتلاتة oxygen، واسمه iron three… التلاتة دي منين؟","screen_text":"Fe₂O₃: iron (III) oxide. Why III?"},{"id":"l2","visual":"YK.termCard({term:'Oxidation state', def:'The charge an atom has, or seems to have, in a compound or ion.', keys:['charge','seems to have']}) at y 560 (lesson wording), from cue 'oxidation'; the 'Fe_2O_3' label hides while the card is up; tokens stay at y 1050. The one definition card (S7b). New term 1.","tts_text":"دي الـ oxidation state: الشحنة اللي الـ atom شايلها، أو كأنه شايلها.","screen_text":"Oxidation state: the charge an atom has, or seems to have"},{"id":"l3","visual":"Card exits (band now holds 'Oxidation state', 64). Each O token gets a tag '−2' (cyan, 56) on cue 'oxygen'; YK.label 'sum = 0' (mono 64, mint, y 1400) on cue 'صفر'. No balance (one ledger carries the sum: fewer objects). Prereq chip 'Valency and writing chemical formulas', <= 2 s.","tts_text":"في الـ compound، الـ oxygen غالباً سالب اتنين، والمجموع صفر.","screen_text":"In a compound: O = −2 · sum = 0"},{"id":"l4","visual":"Ledger under the tokens (mono 56, y 1250): under the 3 O tokens '3 × (−2) = −6' on the FIRST 'ستة' (YK.cue('l4','ستة')); the two Fe tokens light up with a bracket on cue 'iron' and '+6' (gold) on the second 'ستة' (YK.cue('l4','ستة',1)). 'sum = 0' stays below.","tts_text":"تلاتة oxygen يعني سالب ستة، فالاتنين iron لازم موجب ستة.","screen_text":"3 × (−2) = −6 → 2 Fe = +6"},{"id":"l5","visual":"The '+6' bracket splits: each Fe token gets '+3' (gold) on cue 'iron'; on cue 'الاسم' an arrow carries '+3' up into the band, where 'III' pulses gold (band text 'Fe_2O_3: iron (!{III}) oxide').","tts_text":"يعني كل iron موجب تلاتة… ودي التلاتة اللي في الاسم.","screen_text":"Each Fe = +3 → iron (III)"},{"id":"l6","style":"curious","visual":"New-case check (book table p.8 lists MnO₂; lesson used FeO, Fe₂O₃, CrCl₃, KMnO₄, Fe₂(SO₄)₃). Tokens morph to 1 'Mn' + 2 'O' on cue 'manganese'; YK.label 'MnO_2' (mono 120, y 820); YK.band 'MnO_2: oxidation state of Mn?' on cue 'oxidation'; Mn token shows '?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l6','فكّروا'), end: YK.cue('l7')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"طب manganese واتنين oxygen: الـ oxidation state بتاع الـ manganese كام؟ فكّروا. <long pause>","screen_text":"MnO₂: oxidation state of Mn?"},{"id":"l7","visual":"Answer: O tags '−2', '−2' and ledger '−4' on the FIRST 'أربعة'; Mn token flips '?' → '+4' (gold) on cue 'manganese'; 'sum = 0' flashes mint; ONE YK.rightMark.","tts_text":"اتنين oxygen سالب أربعة، فالـ manganese موجب أربعة.","screen_text":"MnO₂: Mn = +4"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'Oxidation state in compounds', line:'In a compound, oxidation states add up to 0', formula:'Fe_2O_3: 2(+3) + 3(−2) = 0', t, pulse:[{word:'0', at:YK.cue('l8','صفر')}]}) >= 2.5 s. Loop: last 0.8 s back to the Fe₂O₃ tokens with the glowing 'III'.","tts_text":"في الـ compound، الـ oxidation states مجموعها صفر.","screen_text":"In a compound, oxidation states add up to 0"}],"logline":"Fe₂O₃ carries no written charge, yet it is iron (III) oxide: with O = −2 and a sum of zero, each iron is +3; the Roman numeral is the metal's oxidation 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oxide ده فيه اتنين iron وتلاتة oxygen\nواسمه iron three التلاتة دي منين\nدي الـ oxidation state الشحنة اللي الـ\natom شايلها أو كأنه شايلها\nفي الـ compound الـ oxygen غالبا سالب\nاتنين والمجموع صفر\nتلاتة oxygen يعني سالب ستة فالاتنين iron\nلازم موجب ستة\nيعني كل iron موجب تلاتة ودي التلاتة اللي\nفي الاسم\nطب manganese واتنين oxygen الـ oxidation\nstate بتاع الـ manganese كام فكّروا\nاتنين oxygen سالب أربعة فالـ manganese\nموجب أربعة\nفي الـ compound الـ oxidation states\nمجموعها صفر","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":14},{"id":"chem-s3-en.video-short-redox.electronic","kind":"short","version":1,"ord":179,"content_lang":"ar-EG","primary_concept_id":"redox.electronic","concepts":[{"concept_id":"redox.electronic","role":"primary"}],"title":"Oxidation and reduction by electrons","payload":{"title":"Oxidation and reduction by electrons","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete: YK.band at 0 'Oxidation !{without oxygen}?' (Cairo 1000, 96; accentAt cue 'oxygen'). Stage: YK.label 'Fe^{2+}' (mono 160, x 360, y 1000) with one cyan YK.dot orbiting it (circle r 150, angle = 2t) from frame 0; a YK.arrow to a ghost 'Fe^{3+}' (40%, x 800); on cue 'oxygen' YK.label 'O_2' (coral, 64) appears struck by a small YK.wrongMark. Prereq chip 'Oxidation and reduction by oxygen', <= 2 s. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"الـ iron two بيبقى iron three… من غير oxygen خالص. ده oxidation إزاي؟","screen_text":"Fe²⁺ → Fe³⁺: oxidation without oxygen?"},{"id":"l2","visual":"On cue 'electron' the orbiting dot flies off up-right (trail, G23) and the token becomes 'Fe^{3+}'; equation YK.formula 'Fe^{2+} -> Fe^{3+} + e^-' (mono 64, y 1350; the short's one equation) builds; YK.label '+2 → +3' (mono 64, y 1480) with a gold YK.arrow pointing up on cue 'زادت' (no kit meter: momentMeter is an unpaired-electron gauge); YK.cueLabel 'oxidation' (64) on the 2nd 'oxidation' (YK.cue('l2','oxidation',1)). Prereq chip 'Oxidation state in compounds', <= 2 s. New meaning 1.","tts_text":"الـ iron خسر electron، والـ oxidation state زادت… ده اسمه oxidation برضه.","screen_text":"Fe²⁺ → Fe³⁺ + e⁻ · +2 → +3"},{"id":"l3","visual":"Myth (concept misconception, R11/G40): small coral card 'Oxidation always needs oxygen' (48) + YK.wrongMark on cue 'غلط', exits after 0.4 s; then the bigger mint card 'Oxidation: loss of electrons' with YK.rightMark on cue 'electrons'.","tts_text":"ناس فاكرة إن الـ oxidation لازم oxygen… غلط، العبرة بالـ electrons اللي راحت.","screen_text":"Needs oxygen ✕   Loss of electrons ✓"},{"id":"l4","visual":"Mirror beat: the Fe group shrinks to the left half; 'Cu^{2+}' token (mono 140, x 760) gains two cyan dots flying IN on cue 'electrons' → 'Cu'; YK.cueLabel 'reduction' (64) on cue 'reduction'; YK.label '+2 → 0' with a cyan YK.arrow pointing down on cue 'بتقل'. New meaning 2 (>= 1 s after l2).","tts_text":"والعكس، اللي يكسب electrons بيحصله reduction، والـ oxidation state بتقل.","screen_text":"Reduction: gain of electrons (state decreases)"},{"id":"l5","visual":"Pair on one row (LTR): 'Zn' (loses, left) and 'Cu^{2+}' (gains, right) — the lesson's Zn/Cu pair; do NOT pair Fe²⁺ with Cu²⁺ (Fe²⁺ does not reduce Cu²⁺). Tag 'oxidizing agent' (52, cyan) pins on the Cu²⁺ side on cue 'oxidizing'; 'is reduced' under it on cue 'reduction'; two electrons stream left → right on cue 'بياخد' ('Zn' → 'Zn^{2+}', 'Cu^{2+}' → 'Cu'). No equation (S3b). Prereq term from redox.basic.","tts_text":"والـ oxidizing agent بيحصله reduction، لأنه هو اللي بياخد الـ electrons دي.","screen_text":"Oxidizing agent: gains electrons (is reduced)"},{"id":"l6","style":"curious","visual":"New-case check (lesson used Fe, Mg, Zn/Cu, Na, Cl, Sn, Fe³⁺). Stage: 'Cr^{3+}' token (mono 140) on cue 'chromium' with a ghost arrow to 'Cr^{2+}' on cue 'two'; two pills 'oxidation' / 'reduction' (52) on their cue words. YK.band 'Cr^{3+} → Cr^{2+}: oxidation or reduction?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l6','فكّروا'), end: YK.cue('l7')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"الـ chromium three بقى chromium two… ده oxidation ولا reduction؟ فكّروا. <long pause>","screen_text":"Cr³⁺ → Cr²⁺: oxidation or reduction?"},{"id":"l7","visual":"Answer: the 'reduction' pill turns mint + ONE YK.rightMark on cue 'reduction'; one cyan dot flies IN to Cr on cue 'electron'; YK.label '+3 → +2' with a cyan YK.arrow pointing down on cue 'قلت'.","tts_text":"ده reduction: كسب electron، والـ oxidation state قلت لاتنين.","screen_text":"Reduction: gained 1 electron, +3 → +2"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'Oxidation and reduction by electrons', line:'Oxidation = loss of electrons · reduction = gain', formula:'Fe^{2+} → Fe^{3+} + e^-', t, pulse:[{word:'loss', at:YK.cue('l8','خسارة')},{word:'gain', at:YK.cue('l8','كسبها')}]}) >= 2.5 s. Loop: last 0.8 s back to the Fe²⁺ token with its orbiting electron.","tts_text":"الـ oxidation خسارة electrons، والـ reduction كسبها.","screen_text":"Oxidation = loss of electrons · reduction = gain"}],"logline":"Fe²⁺ → Fe³⁺ is oxidation with no oxygen at all: oxidation is loss of electrons (oxidation state rises), reduction is gain (it falls), and the oxidizing agent is the one that is 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iron two بيبقى iron three من غير\noxygen خالص ده oxidation إزاي\nالـ iron خسر electron والـ oxidation state\nزادت ده اسمه oxidation برضه\nناس فاكرة إن الـ oxidation لازم oxygen غلط\nالعبرة بالـ electrons اللي راحت\nوالعكس اللي يكسب electrons بيحصله\nreduction والـ oxidation state بتقل\nوالـ oxidizing agent بيحصله reduction لأنه\nهو اللي بياخد الـ electrons دي\nالـ chromium three بقى chromium two ده\noxidation ولا reduction فكّروا\nده reduction كسب electron والـ oxidation\nstate قلت لاتنين\nالـ oxidation خسارة electrons والـ\nreduction كسبها","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":15},{"id":"chem-s3-en.video-short-te.fe2-fe3-mn2-stability","kind":"short","version":1,"ord":181,"content_lang":"ar-EG","primary_concept_id":"te.fe2-fe3-mn2-stability","concepts":[{"concept_id":"te.fe2-fe3-mn2-stability","role":"primary"}],"title":"Iron(II) is easily oxidized while manganese(II) is not","payload":{"title":"Iron(II) is easily oxidized while manganese(II) is not","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete (rubric GOOD 1 pattern): YK.band at 0 'Fe^{2+} → Fe^{3+}: !{why so easy}?' (Cairo 1000, 96). Stage: YK.configStrip(ctx, 540, 1050, {el:'Fe', charge:2, remove:1, size:100, tag:true, label:'below'}) ('[Ar] 3d^6'); the paired box (box 0, ↑↓) YK.flashRect pink pulsing from frame 0. Prereq chip 'Oxidation and reduction by electrons', <= 2 s. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"الـ iron two بيبقى iron three بسهولة جداً… ليه؟","screen_text":"Fe²⁺ → Fe³⁺: why so easy?"},{"id":"l2","visual":"Prereq chip 'Ions: 4s electrons are lost first' (<= 2 s) at line start; live label '[Ar] 3d^6' highlights on cue 'three'; the paired box gets a pink ring + label 'one pair' (48) on cue 'pair'. Book p.9 exercise.","tts_text":"الـ iron two plus آخره three d ستة، فيه pair واحد بس.","screen_text":"Fe²⁺: [Ar] 3d⁶ (one pair)"},{"id":"l3","visual":"charge 3, remove = lerp(2/3, 1, prog(cue 'electron', +0.8)): the paired ↓ electron leaves up-right with trail; tag 'Fe^3+', live label '[Ar] 3d^5' flashes on cue 'three'; stable 0→1 with stableText:'half filled · more stable' (book diagram wording) on cue 'half-filled'. Prereq chip 'Abnormal electronic configuration of chromium and copper', <= 2 s.","tts_text":"لما يخسر electron، يبقى three d خمسة… half-filled، وده أثبت.","screen_text":"Fe³⁺: [Ar] 3d⁵ half filled → more stable"},{"id":"l4","visual":"Aha hold >= 1.5 s: YK.formula 'Fe^{2+} -> Fe^{3+}' (mono 64, y 1400) with a gold 'oxidation' label over the arrow (as in the book diagram p.9); the Fe³⁺ strip glows mint (YK.flashRect) on cue 'iron'. The short's one reaction (S3b).","tts_text":"فالتفاعل بيروح ناحية الـ iron three، لأنه أثبت.","screen_text":"→ toward the more stable Fe³⁺"},{"id":"l5","visual":"Myth (concept misconception 2, G40): small coral tag '3+ > 2+' (48) with YK.wrongMark on cue 'غلط', exits 0.4 s later; then the five singly-filled 3d boxes flash mint L→R + YK.rightMark on cue 'three' with label '3d^5' (56).","tts_text":"ناس فاكرة إنه أثبت عشان شحنته أكبر… غلط، السر في الـ three d خمسة.","screen_text":"3+ > 2+ ✕ · 3d⁵ ✓"},{"id":"l6","style":"curious","visual":"New case for this short (the book's paired example; rubric GOOD 1). Fe strip + arrow slide up to y 700 and dim (dim:1); fresh configStrip({el:'Mn', charge:2, remove:1, size:100, tag:true, label:'none'}) at y 1150 on cue 'manganese'; hint YK.label '_{25}Mn: [Ar] 4s^2 3d^5' (48, 70%) at y 1290; YK.band 'Mn^{2+} → Mn^{3+}: easy too?' on cue 'three'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l6','فكّروا'), end: YK.cue('l7')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"طب الـ manganese two… هيبقى manganese three بسهولة برضه؟ فكّروا. <long pause>","screen_text":"Mn²⁺ → Mn³⁺: easy too?"},{"id":"l7","visual":"Answer: the Fe strip exits; Mn label fades in (label:'below', '[Ar] 3d^5') on cue 'three'; stable 0→1 (stableText:'half filled') on cue 'half-filled' + ONE YK.rightMark. Then a ghost configStrip({el:'Mn', charge:3, size:80, dim:1, label:'none'}) at y 760 labelled 'Mn^{3+}: [Ar] 3d^4' (48, coral) with a ghost arrow up from Mn²⁺ and YK.cueLabel 'not readily oxidized' (48, book p.9) on the last cue word of the line (YK.cueEnd('l7') − 0.4).","tts_text":"لأ، الـ manganese two plus أصلاً three d خمسة، half-filled… فمش بيتأكسد بسهولة.","screen_text":"Mn²⁺: already 3d⁵, half filled ✓ · not readily oxidized"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'Iron(II) is easily oxidized while manganese(II) is not', line:'3d⁵ half filled: more stable', formula:'Fe^3+ · Mn^2+: [Ar] 3d^5', t, pulse:[{word:'half', at:YK.cue('l8','half-filled')}]}) >= 2.5 s. Loop: last 0.8 s back to the Fe²⁺ strip with the paired electron pulsing.","tts_text":"الـ three d خمسة half-filled، يعني أثبت.","screen_text":"3d⁵ half filled: more stable"}],"logline":"Fe²⁺ (3d⁶) gives up its paired electron to become Fe³⁺ (3d⁵), a half-filled, more stable sublevel, so it is easily oxidized; Mn²⁺ is already 3d⁵, so it is not readily oxidized to 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iron two بيبقى iron three بسهولة جدا\nليه\nالـ iron two plus آخره three d ستة فيه\npair واحد بس\nلما يخسر electron يبقى three d خمسة\nhalf-filled وده أثبت\nفالتفاعل بيروح ناحية الـ iron three لأنه\nأثبت\nناس فاكرة إنه أثبت عشان شحنته أكبر غلط\nالسر في الـ three d خمسة\nطب الـ manganese two هيبقى manganese three\nبسهولة برضه فكّروا\nلأ الـ manganese two plus أصلا three d\nخمسة half-filled فمش بيتأكسد بسهولة\nالـ three d خمسة half-filled يعني أثبت","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":16},{"id":"chem-s3-en.video-short-te.oxidation-states-trend","kind":"short","version":1,"ord":183,"content_lang":"ar-EG","primary_concept_id":"te.oxidation-states-trend","concepts":[{"concept_id":"te.oxidation-states-trend","role":"primary"}],"title":"Oxidation states from Sc to Zn","payload":{"title":"Oxidation states from Sc to Zn","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete: YK.band at 0 'Mn: !{+7}. Zn: only +2?' (Cairo 1000, 100). Stage: YK.oxStates(ctx, 108, 700, 864, 940, {grow:1, line:0, highlight:['Mn','Zn'], hp:1, t}) — a DOT plot (one violet dot per book oxidation state, axis +1…+7; no title: the band carries it); highlight pulses Mn's +7 and Zn's +2 from frame 0; YK.flashRect on the Mn column on cue 'manganese', Zn's on cue 'zinc'. Prereq chip 'Oxidation state in compounds', <= 2 s. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"الـ manganese بيوصل لموجب سبعة… والـ zinc موجب اتنين بس. ليه؟","screen_text":"Mn: +7. Zn: only +2?"},{"id":"l2","visual":"Plot rebuilds Sc→Mn only: oxStates grow is a 3-column stagger, so pass data = YK.series1 with Fe…Zn ox:[] (symbols only) and line:0, pop Sc…Mn dots in from cue 'scandium' to cue 'لسبعة'; the page draws the gold max line Sc +3 → Ti +4 → V +5 → Cr +6 → Mn +7 with the returned px/py in the same span. Book table p.8.","tts_text":"من الـ scandium للـ manganese، أعلى oxidation state بتزيد لسبعة.","screen_text":"Highest oxidation state: Sc +3 → Mn +7"},{"id":"l3","visual":"Under the Sc…Mn symbols count chips '3' '4' '5' '6' '7' (YK.label mono 48, mint, y ≈ 1665) pop L→R 0.1 s apart on cue 'electrons' (electrons in 4s + 3d: Cr 4s¹3d⁵ = 6); a gold tick on each max dot on cue 'كلها'. Prereq chip 'Ions: 4s electrons are lost first', <= 2 s.","tts_text":"لحد هنا، بتساوي عدد electrons الـ four s والـ three d كلها.","screen_text":"Sc → Mn: highest = 4s + 3d electrons"},{"id":"l4","visual":"Full data (YK.series1): Fe…Zn dots fade in L→R from cue 'بتقل' to cue 'zinc'; the page-drawn gold line continues Mn +7 → Fe +6 → Co +4 → Ni +4 → Cu +2 → Zn +2; Zn's +2 glows on cue 'اتنين'. Book point 4 p.9.","tts_text":"بعد الـ manganese بتقل تدريجياً، لحد الـ zinc موجب اتنين.","screen_text":"After Mn: decreases to Zn +2"},{"id":"l5","visual":"Myth (concept misconception 1, G40): a dashed coral ghost dot at Fe +8 (py(8), one row above +7) on a dashed stem from Fe's +6, YK.wrongMark on cue 'غلط', gone 0.4 s later; Fe's real +6 dot pulses gold + ONE YK.rightMark on cue 'ستة', tag 'Na_2FeO_4' (48, book table p.8) beside it.","tts_text":"ناس فاكرة الـ iron بيوصل لموجب تمانية… غلط، الكتاب بيقول ستة بس.","screen_text":"Fe: +8 ✕   +6 ✓"},{"id":"l6","visual":"Count chips swap to the book group labels under the symbols on cue 'group' (YK.label 40, mono, staggered on 2 lines so 'VIIB' and 'VIII' do not touch): IIIB IVB VB VIB VIIB, one bracketed 'VIII' spanning Fe–Ni, IB, IIB. A short dashed gold cap tick at each column's group number (Sc +3 … Mn +7, VIII cap at py(8) above the axis, IB cap at +1, IIB at +2). On cue 'copper' Cu's +2 dot gets a gold ring above its IB cap + YK.cueLabel 'IB: +2' (48). Page-drawn on oxStates px/py (dBlockZoom cannot overlay the plot). Prereq chip 'Main transition elements (d-block)', <= 2 s. Book p.9 point 4.","tts_text":"والأعلى مبيعديش رقم الـ group… إلا group الـ copper، بيوصل لاتنين.","screen_text":"Max ≤ group number, except group IB (Cu: +2)"},{"id":"l7","style":"curious","visual":"New-case check (myth used Fe; lesson tested Mo, Au, Ti). Gold line hidden (line 0); Co's dots hidden (data with Co ox:[]) and a gold '?' at its dashed VIII cap (+8); the 'Co' symbol flashes on cue 'cobalt'; YK.band 'Co (group VIII): +8?' on cue 'group'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"طب الـ cobalt في group تمانية… هيوصل لموجب تمانية؟ فكّروا. <long pause>","screen_text":"Co (group VIII): +8?"},{"id":"l8","visual":"Answer: Co's dots +2, +3, +4 pop in on cue 'أربعة', top +4 gold; ONE YK.rightMark; the +8 cap stays dashed far above.","tts_text":"لأ، أربعة بس.","screen_text":"Co: +4 only (book table)"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Oxidation states from Sc to Zn', line:'Rises to Mn (+7), then decreases to Zn (+2)', t, pulse:[{word:'Mn', at:YK.cue('l9','manganese')},{word:'Zn', at:YK.cue('l9','zinc')}]}) >= 2.5 s over the full plot dimmed 35%. Loop: last 0.8 s back to the l1 plot with Mn and Zn glowing.","tts_text":"تطلع للـ manganese سبعة، وتنزل للـ zinc اتنين.","screen_text":"Rises to Mn (+7), then decreases to Zn (+2)"}],"logline":"The highest oxidation state climbs from Sc (+3) to Mn (+7), using every 4s and 3d electron, then falls to Zn (+2); it does not exceed the group number except in group IB, and group VIII stays well below 8 (Fe +6, Co 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manganese بيوصل لموجب سبعة والـ zinc\nموجب اتنين بس ليه\nمن الـ scandium للـ manganese أعلى\noxidation state بتزيد لسبعة\nلحد هنا بتساوي عدد electrons الـ four s\nوالـ three d كلها\nبعد الـ manganese بتقل تدريجيا لحد الـ\nzinc موجب اتنين\nناس فاكرة الـ iron بيوصل لموجب تمانية غلط\nالكتاب بيقول ستة بس\nوالأعلى مبيعديش رقم الـ group إلا group\nالـ copper بيوصل لاتنين\nطب الـ cobalt في group تمانية هيوصل لموجب\nتمانية فكّروا\nلأ أربعة بس\nتطلع للـ manganese سبعة وتنزل للـ zinc\nاتنين","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":17},{"id":"chem-s3-en.video-short-pt.atomic-radius-trend","kind":"short","version":1,"ord":185,"content_lang":"ar-EG","primary_concept_id":"pt.atomic-radius-trend","concepts":[{"concept_id":"pt.atomic-radius-trend","role":"primary"}],"title":"Atomic radius trend","payload":{"title":"Atomic radius trend","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete: YK.band at 0 'More electrons. !{Smaller}?' (Cairo 1000, 100). Stage (YK.atomDisc has no electrons → Bohr YK.atom): Na YK.atom(ctx, 345, 1050, {shells:[2,8,1], size:230, rotate:t}) LEFT, Cl YK.atom(ctx, 800, 1050, {shells:[2,8,7], size:122, rotate:t}) RIGHT (size ratio 0.99/1.86 from the lesson chart), YK.label 'Na' / 'Cl' (56) under each; Cl YK.flashRect on cue 'chlorine', Na on cue 'sodium'. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"الـ chlorine فيه electrons أكتر من الـ sodium… وأصغر منه. إزاي؟","screen_text":"More electrons. Smaller?"},{"id":"l2","visual":"Both outer rings gold (highlightShell:2) with tag 'n = 3' (48) on cue 'outer'; YK.cueLabel 'Period 3' (52) on cue 'period'. Prereq chip 'Periodic table: periods and groups', <= 2 s.","tts_text":"الاتنين في نفس الـ period، والـ outer level واحد.","screen_text":"Same period: same outer level (n = 3)"},{"id":"l3","visual":"YK.label '11 p^+' under Na and '17 p^+' under Cl (coral, 52) on cue 'protons'; four inward YK.arrow on Cl's outer ring thicken and the ring tightens 5% on cue 'لجوه'.","tts_text":"بس الـ chlorine فيه protons أكتر، فبيشد لجوه أقوى.","screen_text":"More protons → stronger pull"},{"id":"l4","visual":"Do NOT draw the period-3 row Na → Cl (it would show Mg and S, the l7 check). Keep the two atoms: a radius bracket (nucleus → outer ring) on Na + YK.cueLabel 'atomic radius' (52) on cue 'atomic'; a gold YK.arrow from Na to Cl under them (y 1400) + YK.cueLabel 'decreases' (52) on cue 'بيقل'. New term 1.","tts_text":"فالـ atomic radius بيقل على طول الـ period ده.","screen_text":"Across a period: atomic radius decreases"},{"id":"l5","visual":"Clear; vertical stack top → bottom (G18): YK.atom Li {shells:[2,1], size:182} at (540, 800) and Na {shells:[2,8,1], size:223, reveal} at (540, 1250) (1.52 : 1.86 from the lesson); Na's 3rd ring draws on cue 'level'; YK.arrow down + YK.cueLabel 'larger' on cue 'بيكبر'; labels 'Li 1.52 Å' / 'Na 1.86 Å' (48) to the right of each.","tts_text":"لكن نازلين في الـ group، كل period بيزوّد level، فالـ atom بيكبر.","screen_text":"Down a group: + 1 level → larger"},{"id":"l6","visual":"Aha (hold >= 1.5 s): YK.tug(ctx, 540, 1050, 300, {el:'Na', pull: prog(cue 'nucleus'), push: prog(cue 'repulsion'), labels:{pull:'nucleus: pull in', push:'repulsion: push out'}, t}) (override the kit's default '3d repulsion' label: this is a main-group atom). Prereq chip 'Electric charges attract and repel', <= 2 s. New term 2.","tts_text":"قوتين: الـ nucleus بيشد لجوه، والـ repulsion بين الـ electrons بتزق لبره.","screen_text":"Pull in: nucleus · Push out: repulsion"},{"id":"l7","style":"curious","visual":"New-case check (lesson worked Na/Cl, Li/Na, Li-B-N-F, Br/Cl; Mg and S never drawn earlier in this short). Two equal grey YK.atomDisc (r 170) 'Mg' (x 330) and 'S' (x 750) with tags 'Z = 12' / 'Z = 16' (48) on cues 'magnesium' / 'sulphur'; YK.band 'Mg or S: which is larger?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"طب الـ magnesium والـ sulphur، نفس الـ period… مين أكبر؟ فكّروا. <long pause>","screen_text":"Mg or S (period 3): which is larger?"},{"id":"l8","visual":"Answer: discs tween to Mg r 200 / S r 130 (lesson 1.60 / 1.04 Å) on cue 'magnesium'; labels '12 p^+' vs '16 p^+' (coral, 52) on cue 'protons'; ONE YK.rightMark by Mg.","tts_text":"الـ magnesium: protons أقل، فالشد أضعف.","screen_text":"Mg: fewer protons, weaker pull"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Atomic radius trend', line:'Across a period: smaller · down a group: larger', t, pulse:[{word:'smaller', at:YK.cue('l9','بيصغّره')},{word:'larger', at:YK.cue('l9','بيكبّره')}]}) >= 2.5 s. Loop: last 0.8 s back to the Na / Cl discs side by side.","tts_text":"الـ period بيصغّره، والنزول في الـ group بيكبّره.","screen_text":"Across a period: smaller · down a group: larger"}],"logline":"Chlorine has more electrons than sodium yet is smaller: in the same period the outer level is the same and more protons pull it in, so the atomic radius decreases across a period and increases down a group, a balance of nuclear pull and electron 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Why only !{Na^+}?' (Cairo 1000, 96). Stage: YK.atom(ctx, 540, 1000, {shells:[2,8], size:200, rotate:t}) + a page-drawn n = 3 ring (r 290) with its single electron (YK.dot) that drifts 60 px out and snaps back (1.5 s loop) from frame 0; ghost 'Na^+' (40%, mono 72) top-right. Prereq chip 'Ions (cations and anions)', <= 2 s. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"الـ sodium فيه حداشر electron… وعمره ما بيخسر غير واحد. ليه؟","screen_text":"Na: 11 electrons. Why only Na⁺?"},{"id":"l2","visual":"YK.termCard({term:'Ionization energy (ionization potential)', def:'The energy needed to remove the most loosely held electron from a gaseous atom.', keys:['remove','most loosely held','gaseous atom']}) at y 560 on cue 'ionization' (lesson wording; book p.10 calls it 'ionization potential'); the atom shrinks to y 1350, size 140. The one definition card. New term 1.","tts_text":"الـ ionization energy هي الطاقة اللي تشيل أضعف electron من atom غازي.","screen_text":"Ionization energy: energy to remove the most loosely held electron from a gaseous atom"},{"id":"l3","visual":"Card exits; the atom moves to (300, 760), size 150. On cue 'electron' its 3s electron flies off up-right with trail. YK.chart(ctx, 108, 1000, 864, 640, {type:'bar', data:[{x:'1st',y:496},{x:'2nd',y:4562*p2},{x:'3rd',y:6910*p3}], yRange:[0,7000], ticks:2, xLabel:'Electron removed', grow:1}) (lesson values, kJ/mol; fixed yRange so bars rise one at a time without rescaling): bar 1 rises on cue 'فسهل'. Prereq chip 'Atomic radius trend', <= 2 s.","tts_text":"أول electron بييجي من الـ three s، الـ outer level، فسهل.","screen_text":"1st electron: from 3s, the outer level"},{"id":"l4","visual":"p2 0→1 on cue 'التاني', p3 0→1 on cue 'التالت'; YK.cueLabel 'each one larger' (52) on cue 'أكبر'.","tts_text":"وبعده التاني والتالت… كل واحدة أكبر من اللي قبلها.","screen_text":"Each one is larger than the one before"},{"id":"l5","visual":"Bar 2 YK.flashRect gold with a bracket from bar 1's top to bar 2's top and YK.label '≈ 9 ×' (mono 64) on cue 'تسع'; YK.cueLabel 'big jump' (56) on cue 'قفزة'. Value check: lesson 4562 / 496 = 9.2 (not in the book; the lesson is approved).","tts_text":"بس التاني أكبر تسع مرات تقريباً: قفزة كبيرة.","screen_text":"2nd ≈ 9 × 1st: big jump"},{"id":"l6","visual":"Aha hold: the atom (top-left) is now Na⁺: its n = 2 ring (8 electrons) glows mint (highlightShell:1) + label 'stable inner level' (48) on cue 'inner'; then YK.label 'Na^+ only' (mono 72, gold) on cue 'sodium'.","tts_text":"لأنه بيطلع من inner level ثابت، فالـ sodium بيقف عند موجب واحد.","screen_text":"2nd: from a stable inner level → Na⁺ only"},{"id":"l7","style":"curious","visual":"New-case check (lesson used Na and metal X = Al data; no Mg numbers shown). Chart exits; YK.atom(ctx, 540, 900, {shells:[2,8,2], size:240, highlightShell:2}) on cue 'magnesium', its two outer electrons gold on cue 'three'; four dashed empty bar outlines with '?' at y 1250–1600; YK.band 'Mg (3s^2): big jump after which electron?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"طب الـ magnesium آخره three s اتنين… القفزة بعد كام electron؟ فكّروا. <long pause>","screen_text":"Mg ([Ne] 3s²): big jump after which electron?"},{"id":"l8","visual":"Answer: page-drawn bars (no axis, no numbers; heights ∝ 738 / 1451 / 7733): two short bars, then a tall 3rd bar with a 'big jump' bracket on cue 'التاني'; tag 'Mg^{2+}' (gold) on cue 'magnesium'; ONE YK.rightMark.","tts_text":"بعد التاني، فالـ magnesium موجب اتنين بس.","screen_text":"After the 2nd: Mg shows +2"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Ionization energy', line:'Big jump = a stable inner level', t, pulse:[{word:'jump', at:YK.cue('l9','القفزة')},{word:'stable', at:YK.cue('l9','ثابت')}]}) >= 2.5 s. Loop: last 0.8 s back to the Na disc with its 3s electron drifting off and snapping back.","tts_text":"القفزة الكبيرة معناها inner level ثابت.","screen_text":"Big jump = a stable inner level"}],"logline":"Sodium has 11 electrons but only ever forms Na⁺: each successive ionization energy is larger, and the 2nd one jumps about ninefold because that electron must leave a stable inner 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sodium فيه حداشر electron وعمره ما\nبيخسر غير واحد ليه\nالـ ionization energy هي الطاقة اللي تشيل\nأضعف electron من atom غازي\nأول electron بييجي من الـ three s الـ\nouter level فسهل\nوبعده التاني والتالت كل واحدة أكبر من اللي\nقبلها\nبس التاني أكبر تسع مرات تقريبا قفزة كبيرة\nلأنه بيطلع من inner level ثابت فالـ sodium\nبيقف عند موجب واحد\nطب الـ magnesium آخره three s اتنين القفزة\nبعد كام electron فكّروا\nبعد التاني فالـ magnesium موجب اتنين بس\nالقفزة الكبيرة معناها inner level ثابت","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":19},{"id":"chem-s3-en.video-short-te.multiple-oxidation-states","kind":"short","version":2,"ord":189,"content_lang":"ar-EG","primary_concept_id":"te.multiple-oxidation-states","concepts":[{"concept_id":"te.multiple-oxidation-states","role":"primary"}],"title":"Why several oxidation states","payload":{"title":"Why several oxidation states","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete: YK.band at 0 'Na: one oxidation state. V: !{four}?' (Cairo 1000, 90). Stage: YK.elementCard(ctx, 320, 1000, {sym:'Na', w:400, config:''}) and YK.elementCard(ctx, 760, 1000, {sym:'V', w:400, config:''}); under Na one chip '+1', under V four chips '+2 +3 +4 +5' (book table p.8) fanning out from frame 0; Na glows on cue 'sodium', V on cue 'vanadium'. Prereq chip 'Oxidation states from Sc to Zn', <= 2 s. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"الـ sodium له oxidation state واحدة… والـ vanadium أربعة. ليه؟","screen_text":"Na: one oxidation state. V: four?"},{"id":"l2","visual":"Cards exit; YK.stairs(ctx, 108, 600, 864, 920, {values:[648,1346,2858,4643,6523], species:['V','V^+','V^2+','V^3+','V^4+','V^5+'], step:0, title:'Ionization energies of vanadium', unit:'kJ/mol'}) on cue 'ionization'. Prereq chip 'Ionization energy', <= 2 s. Book p.10 flowchart.","tts_text":"الـ ionization energies بتاعة الـ vanadium بتقول إيه؟","screen_text":"Ionization energies of vanadium (kJ/mol)"},{"id":"l3","visual":"step 0→1 on cue 'ستمية', 1→2 on cue 'ألف' (needle 'ألف': the tts word is 'وألف'); the stairs' own electron leaves on each step (electron:true; no extra configStrip: one focal object); tags '4s' (mint, 44) under treads 1–2 on cue 'four'.","tts_text":"الـ four s: ستمية تمانية وأربعين، وألف تلتمية ستة وأربعين.","screen_text":"4s: 648 → 1346"},{"id":"l4","visual":"step 2→5 from cue 'three' to cue 'بالتدريج'; tags '3d' (violet, 44) under treads 3–5; a gold dashed line traces the gentle slope across all five treads on cue 'بالتدريج'.","tts_text":"وبعدين الـ three d، وبتكمّل تطلع بالتدريج.","screen_text":"3d: 2858 → 4643 → 6523"},{"id":"l5","visual":"Myth (concept misconception 1, G40): dashed coral ghost treads superimposed on the real staircase — treads 3–5 jump as a cliff after tread 2 — + YK.wrongMark on cue 'لأ', gone 0.4 s later; the real stairs pulse + ONE YK.rightMark on cue 'تدريجي'. No sodium inset (one focal object).","tts_text":"ناس فاكرة فيه قفزة ضخمة بعد الـ four s… لأ، تدريجي.","screen_text":"Huge jump after 4s ✕   Gradual rise ✓"},{"id":"l6","visual":"Aha hold >= 1.5 s: the 4s and 3d tread tags slide together into one band labelled 'close in energy' (gold) on cue 'قريبين'; arrows 1→5 'in sequence' on cue 'بالترتيب'. Book p.10 point 5 wording; no energy-order claim (S7a).","tts_text":"عشان الـ four s والـ three d قريبين في الـ energy، فبيطلعوا بالترتيب.","screen_text":"4s and 3d: close in energy, lost in sequence"},{"id":"l7","visual":"State chips '+2 +3 +4 +5' (gold, 44) appear on the V^{2+}…V^{5+} treads on cue 'oxidation' (book table p.8: V has +2…+5; NO '+1' chip on the V⁺ tread); a coral dashed vertical 'wall' bar between treads 2 and 3 fades out on cue 'حيطة'.","tts_text":"مفيش حيطة توقفه، فيعمل oxidation states كتير.","screen_text":"No big jump → several oxidation states"},{"id":"l8","style":"curious","visual":"New-case check (lesson used Na, V, Ca, Mg/Ti data, Ba). Stairs dim 35%; YK.elementCard(ctx, 540, 900, {sym:'Mn', w:400, config:''}) on cue 'manganese' with chips '+2 +3 +4 +6 +7' (book table p.8); pills 'big jump' / 'gradual rise' (52) on cues 'قفزة' / 'تدريجي'; YK.band 'Mn: +2 to +7. Big jump or gradual rise?'. No Mn values shown. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l8'), end: YK.cue('l9')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"طب الـ manganese من اتنين لسبعة… قفزة ولا تدريجي؟ <long pause>","screen_text":"Mn: +2 to +7. Big jump or gradual rise?"},{"id":"l9","visual":"Answer: 'gradual rise' pill turns mint + ONE YK.rightMark on cue 'تدريجي'; the '+7' chip glows on cue 'لسبعة'.","tts_text":"تدريجي، وإلا مكانش وصل لسبعة.","screen_text":"Gradual: no big jump up to +7"},{"id":"l10","visual":"Voiced lock-in: YK.takeaway({title:'Why several oxidation states', line:'Close in energy → several oxidation states', formula:'V: +2, +3, +4, +5', t, pulse:[{word:'energy', at:YK.cue('l10','energy')},{word:'several', at:YK.cue('l10','كتير')}]}) >= 2.5 s (the 5-value formula is wider than 864 px). Loop: last 0.8 s back to the Na (+1) / V (+2…+5) cards.","tts_text":"قريبين في الـ energy، يبقى oxidation states كتير.","screen_text":"Close in energy → several oxidation states"}],"logline":"Sodium has one oxidation state, vanadium four: vanadium's 4s and 3d electrons are close in energy and leave in sequence, so its ionization energies (648, 1346, 2858, 4643, 6523 kJ/mol) rise gradually with no big 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Stage: YK.configStrip(ctx, 540, 1050, {el:'Sc', charge:3, remove:1, size:100, tag:true, label:'below'}) ('Sc^3+', '[Ar] 3d^0'), five empty 3d boxes YK.flashRect pulsing from frame 0; 'three' is spoken twice (scandium three / three d): flash the 3d boxes on YK.cue('l1','three',1). Prereq chip 'Oxidation states from Sc to Zn', <= 2 s. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"الـ scandium three plus الـ three d بتاعته فاضية… transition ولا لأ؟","screen_text":"Sc³⁺: 3d⁰. Transition or not?"},{"id":"l2","visual":"YK.termCard({term:'The transition element', def:'The element in which the orbitals of d or f contain electrons but they are not complete in their atomic state or in one of their oxidation states.', keys:[…], defSize:44}) at y 560 from cue 'التعريف' (book p.10 verbatim, 28 words: verbatim wins over S7b's 25-word cap, R7); the strip slides to y 1450 and dims. keys grow per cue: 'contain electrons' on cue 'electrons', 'not complete' on cue 'كاملة'.","tts_text":"التعريف: الـ d orbitals أو الـ f orbitals فيها electrons، مش كاملة.","screen_text":"The transition element: d or f orbitals contain electrons but are not complete…"},{"id":"l3","visual":"Same card; keys add 'atomic state' on cue 'atom' and 'one of their oxidation states' on cue 'oxidation'; two pills under the card 'Test 1: atom' · OR · 'Test 2: oxidation states' (48) appear with the second key.","tts_text":"في الـ atom، أو أي oxidation state بتاعته.","screen_text":"…in their atomic state or in one of their oxidation states"},{"id":"l4","visual":"Card exits; pills move to y 640 and stay. YK.electronBoxes(ctx, 540, 1100, {label:'3d', boxes:5, size:110, electrons:n}) with n stepping 1→9 from line start to cue 'لتسعة' + tag 'd^n' and a mint frame (incomplete); then n = 0 on cue 'صفر' → coral frame + YK.wrongMark small 'd^0', n = 10 on cue 'عشرة' → coral 'd^{10}'; rest on YK.label 'incomplete: d^1 … d^9' (52, mint).","tts_text":"من واحد لتسعة… مش صفر ولا عشرة.","screen_text":"Incomplete: d¹ to d⁹"},{"id":"l5","visual":"Myth (concept misconception 2, G40): the Sc³⁺ strip returns at y 1100; small coral card 'Sc^{3+} 3d^0 → not transition' (48) over it on cue 'scandium', YK.wrongMark on cue 'غلط'; card exits 0.4 s later.","tts_text":"ناس بتبص على الـ scandium three، وتقول مش transition… غلط.","screen_text":"Sc³⁺ 3d⁰ → not transition ✕"},{"id":"l6","visual":"Aha hold >= 1.5 s: the removed electrons fly back (remove 1→0 on cue 'atom'): 'Sc' [Ar] 4s² 3d¹, the single 3d electron glows gold on cue 'three'; pill 'Test 1: atom' turns mint + YK.rightMark on cue 'transition'. Book: Sc atom 3d¹.","tts_text":"الـ atom نفسه three d واحد، ناقصة، فهو transition element أصلاً.","screen_text":"Sc atom: 3d¹ → transition element ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson used Sc, Mn, Ca, Ga, K, Zn, Ti, Co). Sc strip exits; pills reset to grey; configStrip({el:'V', charge:5, remove:1, size:100, tag:true, label:'below'}) ('V^5+', '[Ar] 3d^0'; book p.10 flowchart V⁵⁺ 4s⁰ 3d⁰) on cue 'vanadium', empty 3d boxes pulse on cue 'three'; YK.band 'V^{5+}: 3d^0. Is V transition?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"الـ vanadium في أعلى oxidation state، الـ three d فاضية… transition؟ فكّروا. <long pause>","screen_text":"V⁵⁺: 3d⁰. Is V transition?"},{"id":"l8","visual":"Answer: remove 1→0 (electrons return) on cue 'atom'; label '[Ar] 4s^2 3d^3' on cue 'three'; 'Test 1: atom' pill mint + YK.rightMark on cue 'ناقصة'.","tts_text":"أيوه، الـ atom بتاعه three d تلاتة، ناقصة.","screen_text":"Yes: V atom 3d³, incomplete ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Definition of the transition element', line:'Incomplete d in the atom or one oxidation state', formula:'Sc: [Ar] 4s^2 3d^1', t, pulse:[{word:'atom', at:YK.cue('l9','atom')},{word:'oxidation', at:YK.cue('l9','oxidation')}]}) >= 2.5 s. Loop: last 0.8 s back to the Sc³⁺ strip with empty pulsing 3d boxes.","tts_text":"ناقصة في الـ atom أو oxidation state، كفاية.","screen_text":"Incomplete d in the atom or one oxidation state"}],"logline":"Sc³⁺ has no 3d electrons, yet scandium is a transition element: the book's definition asks for d (or f) orbitals that hold electrons but are incomplete in the atom OR in one of its oxidation states, and the Sc atom is 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scandium three plus الـ three d بتاعته\nفاضية transition ولا لأ\nالتعريف الـ d orbitals أو الـ f orbitals\nفيها electrons مش كاملة\nفي الـ atom أو أي oxidation state بتاعته\nمن واحد لتسعة مش صفر ولا عشرة\nناس بتبص على الـ scandium three وتقول مش\ntransition غلط\nالـ atom نفسه three d واحد ناقصة فهو\ntransition element أصلا\nالـ vanadium في أعلى oxidation state الـ\nthree d فاضية transition فكّروا\nأيوه الـ atom بتاعه three d تلاتة ناقصة\nناقصة في الـ atom أو oxidation state كفاية","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":21},{"id":"chem-s3-en.video-short-te.definition-applied","kind":"short","version":2,"ord":193,"content_lang":"ar-EG","primary_concept_id":"te.definition-applied","concepts":[{"concept_id":"te.definition-applied","role":"primary"}],"title":"Are coinage metals and zinc transition elements?","payload":{"title":"Are coinage metals and zinc transition elements?","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"Frame 0 complete: YK.band at 0 'Both 3d^{10}. !{Only one} transition?' (Cairo 1000, 90). Stage: two YK.configStrip size 88 stacked top → bottom: Cu at y 880 ('[Ar] 4s^1 3d^10') and Zn at y 1260 ('[Ar] 4s^2 3d^10'), label 'below'; Cu YK.flashRect on cue 'copper', Zn on cue 'zinc'. [Director pass, all lines: every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' at x 108, y 600, <= 2 s, one at a time; one stamp per beat.]","tts_text":"الـ copper والـ zinc الاتنين three d عشرة… واحد بس transition. مين؟","screen_text":"Both 3d¹⁰. Only one transition?"},{"id":"l2","visual":"Prereq chip 'Definition of the transition element' at line start, <= 2 s; on cue 'فشل' a tag 'Atom test' (44) + small YK.wrongMark beside each strip (✕ is drawn, fonts have no glyph); on cue 'الاتنين' textDim brackets 'complete (d^{10})' over both 3d rows (not mint: complete is the failing case here).","tts_text":"اختبار الـ atom فشل في الاتنين.","screen_text":"Atom test: 3d¹⁰ complete in both"},{"id":"l3","visual":"Cu strip: configStrip({el:'Cu', charge:2, remove: prog(cue 'copper', +1.0), tag:true}) — the 4s electron, then one 3d electron (box 5 ↓) leave up-right; live label '[Ar] 3d^9' flashes on cue 'تسعة'; tag 'Ion test' + ONE YK.rightMark on cue 'فنجح'. Book p.10 Exercise 1.","tts_text":"في الـ copper two plus، الـ three d بقت تسعة: ناقصة، فنجح.","screen_text":"Cu²⁺: [Ar] 3d⁹ → incomplete ✓"},{"id":"l4","visual":"Both strips slide off left. Three formula rows (3 elementCards ≥ 380 px do not fit 9:16): YK.label (mono 56, x 160, left-aligned) 'Cu: 4s^1 3d^{10}' (y 950), 'Ag: 5s^1 4d^{10}' (y 1100), 'Au: 6s^1 5d^{10}' (y 1250) (book p.10) on cues 'copper', 'silver', 'gold', each with a mint YK.rightMark at x 900; YK.cueLabel 'Coinage metals' (64, gold, y 780) on cue 'coinage'; shared label 'ions: d^9 or d^8' (48, y 1400). New term 1.","tts_text":"الـ coinage metals، الـ copper والـ silver والـ gold، كلهم.","screen_text":"Coinage metals: Cu, Ag, Au ✓"},{"id":"l5","visual":"Rows exit; the Zn strip slides back at y 1050: charge 0→2 from cue 'zinc' (only the two 4s electrons leave); live label '[Ar] 3d^10' flashes on cue 'three'; the 3d row stays full; YK.wrongMark + YK.cueLabel 'not a transition element' (52, coral) on cue 'transition'. Book p.11 Exercise 2.","tts_text":"أما الـ zinc two plus لسه three d عشرة، فمش transition element خالص.","screen_text":"Zn²⁺ (its only state): 3d¹⁰ → not a transition element"},{"id":"l6","visual":"Myth (concept misconception 2, G40): small coral card 'In the d-block = transition' (48, y 720) + YK.wrongMark on cue 'غلط' (no 60% dBlockZoom: its tiles fall under 40 px), exits 0.4 s later; then the Zn strip pulses grey and YK.cueLabel 'Zn: d^{10} in atom and ion' (48) on cue 'zinc'.","tts_text":"ناس فاكرة الـ d-block كله transition… غلط، الـ zinc أهو.","screen_text":"In the d-block = transition ✕ · Zn: d¹⁰ in atom and ion"},{"id":"l7","style":"curious","visual":"New-case check (lesson worked Cu, Zn, Au, Ag, Pd). Zn strip exits. ONE row for the atom only (the Hg²⁺ row would give the answer away): YK.electronBoxes 6s {boxes:1, electrons:['↑↓'], size:100, label:'6s'} at x 260 + 5d {boxes:5, electrons:10, size:100, label:'5d'} at x 640, y 1000 (book p.11 order: 6s² 5d¹⁰) on cue 'mercury'; YK.label 'Hg' (mono 72) left of it; YK.band 'Hg: 6s^2 5d^{10}. Transition?' on cue 'configuration'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cue('l7','فكّروا'), end: YK.cue('l8')}) (short.js; not YK.checkPause with empty Q/A) through the stitched silence (pause_after_s 1.5 from the trailing <long pause>); the page stamps ONE YK.rightMark/wrongMark with the answer.","tts_text":"الـ mercury، شوفوا الـ configuration بتاعته… transition ولا لأ؟ فكّروا. <long pause>","screen_text":"Hg: 6s² 5d¹⁰. Transition?"},{"id":"l8","visual":"Answer: at line start the 6s electrons fly up-right and a second row 'Hg^{2+}' (6s empty, 5d full) appears at y 1300; on cue 'كاملة' textDim brackets 'complete' over both 5d rows; ONE YK.wrongMark beside the band's 'Transition?' + tag 'like Zn' (48).","tts_text":"لأ، الـ five d كاملة في الاتنين.","screen_text":"No: 5d¹⁰ in the atom and the +2 ion"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Are coinage metals and zinc transition elements?', line:'Cu²⁺ 3d⁹ incomplete · Zn²⁺ 3d¹⁰ complete', t, pulse:[{word:'incomplete', at:YK.cue('l9','ناقص')},{word:'complete', at:YK.cue('l9','كامل')}]}) >= 2.5 s. Loop: last 0.8 s back to the Cu / Zn strips, all 3d boxes full.","tts_text":"الـ copper two ناقص، والـ zinc two كامل.","screen_text":"Cu²⁺ 3d⁹ incomplete · Zn²⁺ 3d¹⁰ complete"}],"logline":"Cu and Zn atoms are both 3d¹⁰, but Cu²⁺ is 3d⁹ (incomplete) so copper and the other coinage metals are transition elements, while Zn²⁺ stays 3d¹⁰ so zinc is 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copper والـ zinc الاتنين three d عشرة\nواحد بس transition مين\nاختبار الـ atom فشل في الاتنين\nفي الـ copper two plus الـ three d بقت\nتسعة ناقصة فنجح\nالـ coinage metals الـ copper والـ silver\nوالـ gold كلهم\nأما الـ zinc two plus لسه three d عشرة فمش\ntransition element خالص\nناس فاكرة الـ d-block كله transition غلط\nالـ zinc أهو\nالـ mercury شوفوا الـ configuration بتاعته\ntransition ولا لأ فكّروا\nلأ الـ five d كاملة في الاتنين\nالـ copper two ناقص والـ zinc two كامل","countable":true,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":22},{"id":"chem-s3-en.video-short-te.atomic-mass-trend","kind":"short","version":1,"ord":244,"content_lang":"ar-EG","primary_concept_id":"te.atomic-mass-trend","concepts":[{"concept_id":"te.atomic-mass-trend","role":"primary"}],"title":"Atomic mass: why nickel is abnormal","payload":{"title":"Atomic mass: why nickel is abnormal","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pass v2, all lines: page.html must add <script> tags for lib/short.js and lib/beats.js (template.html lacks them: YK.band, YK.thinkRing, YK.cueLabel, YK.pill, YK.choice); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; look at stills before render.] Frame 0 complete: two YK.elementCard (w 380, config:'') Co (Z 27) at x 320 and Ni (Z 28) at x 760, y 820, over YK.balance(ctx, 540, 1250, 640, {left:'Co', right:'Ni', value:-0.35}) (value < 0 = left/Co side down) rocking gently ±0.05 from t=0; YK.band 'Ni after Co, yet !{lighter}?' (Cairo 1000, 104) at 0. Ni card hl on cue 'nickel', Co card hl on cue 'cobalt'; the beam dips to value -0.5 on cue 'أخف'.","tts_text":"الـ nickel بعد الـ cobalt… بس أخف منه! إزاي؟","screen_text":"Ni after Co, yet lighter?"},{"id":"l2","visual":"Cards and balance exit (0.3 s). YK.chart(ctx, 108, 640, 864, 820, {type:'bar', data: Sc 45, Ti 47.9, V 51, Cr 52, Mn 54.9, Fe 55.9, Co 58.9, Ni 58.7, Cu 63.5 (book table p.12), yLabel:'Atomic mass', yRange:[40, 66], grow: YK.prog(t, cue 'بتزيد', cue 'يزيد')}); footnote 'Book table p.12, for illustration only' (40, 60%) at y 1500. Prereq chip 'Elements of the first transition series' at line start (<= 2 s). Book p.12 point 1.","tts_text":"الـ atomic mass بتزيد بالتدريج كل ما الـ atomic number يزيد.","screen_text":"Atomic mass increases gradually with atomic number"},{"id":"l3","visual":"chart highlight:['Co','Ni'] (others dim, hp on line start). YK.label '58.9' (mono 56) above the Co bar on cue 'cobalt'; '58.7' above the Ni bar (coral) on cue 'nickel'; a dashed gold line at y = 58.9 across both bars on cue 'nickel' so the Ni bar visibly stops below it.","tts_text":"الـ cobalt تمانية وخمسين فاصل تسعة، والـ nickel تمانية وخمسين فاصل سبعة.","screen_text":"Co 58.9 · Ni 58.7"},{"id":"l4","visual":"Myth (top misconception, R11): small coral YK.pill 'misprint?' (44) over the Ni bar on cue 'مطبعي' + small YK.wrongMark on cue 'لأ' (both gone 0.4 s later); then the '58.7' label grows to 72, turns mint + ONE YK.rightMark on cue 'صح'. The right version bigger and longer on screen.","tts_text":"ناس بتقول ده غلط مطبعي… لأ، الرقم صح.","screen_text":"A misprint? ✕  A real value ✓"},{"id":"l5","visual":"Chart exits. A Ni YK.atomDisc (r 110, y 820) splits into five Ni discs (r 70, equal size, no mass labels) fanned in an arc on cue 'isotopes'; label 'five stable isotopes' (52) at y 1100 on cue 'stable'; a gold bracket gathers the five into one badge '58.7 u' (YK.label mono 56) on cue 'متوسطهم'. Prereq chip 'Isotopes and average atomic mass' at line start. New term 1 (stable isotopes).","tts_text":"الـ nickel ليه خمس stable isotopes، والـ atomic mass بتاعه متوسطهم.","screen_text":"Nickel: five stable isotopes"},{"id":"l6","visual":"The five discs re-size by share: one grows biggest and gets the tag 'Ni-58' (48) on cue 'nickel'. Under them (y 1350) a horizontal scale 58 → 61 (ticks mono 40, 864 px wide, so 0.2 u = 58 px): gold marker 'average' slides to 58.7 on cue 'average'; grey marker 'Co 58.9' appears just right of it on cue 'cobalt'. Approved lesson: nickel-58 is the most common isotope.","tts_text":"ومعظمهم nickel تمانية وخمسين الخفيف، فالـ average بيقل عن الـ cobalt شوية.","screen_text":"Mostly Ni-58 → average 58.7 u"},{"id":"l7","style":"curious","visual":"New-case check (hypothetical mix; lesson used a 58/60 share slider but never this question). On cue 'ستين': the 'Ni-60' disc grows biggest, Ni-58 shrinks; the average marker turns to a grey '?' (Co 58.9 marker stays). YK.band 'Mostly Ni-60: heavier or lighter than Co?' (72) on cue 'أغلبه'. YK.thinkRing(ctx, t, 540, 1540, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); nothing of the answer before YK.cue('l8').","tts_text":"لو أغلبه nickel ستين، يبقى أتقل من الـ cobalt ولا أخف؟","screen_text":"Mostly Ni-60: heavier or lighter than Co?","pause_after_s":2},{"id":"l8","visual":"Answer: the '?' turns gold and slides right past the Co 58.9 marker toward 60 on cue 'average'; ONE YK.rightMark on cue 'أتقل'. No balance callback (one idea).","tts_text":"أتقل، لأن الـ average هيبقى قريب من ستين.","screen_text":"Heavier: average near 60 ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Atomic mass: why nickel is abnormal', line:'Atomic mass: the average of the isotopes', formula:'Ni 58.7 u < Co 58.9 u', t, pulse:[{word:'average', at:YK.cue('l9','average')}, {word:'isotopes', at:YK.cue('l9','isotopes')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s cross-fades to the frame-0 cards + balance.","tts_text":"الـ atomic mass هو average الـ isotopes بتوعه.","screen_text":"Atomic mass: the average of the isotopes","pause_after_s":1.5}],"logline":"Nickel comes after cobalt yet is lighter (58.7 u vs 58.9 u): atomic mass rises gradually with atomic number, but nickel has five stable isotopes and its atomic mass is their average (book 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nickel بعد الـ cobalt بس أخف منه إزاي\nالـ atomic mass بتزيد بالتدريج كل ما الـ\natomic number يزيد\nالـ cobalt تمانية وخمسين فاصل تسعة والـ\nnickel تمانية وخمسين فاصل سبعة\nناس بتقول ده غلط مطبعي لأ الرقم صح\nالـ nickel ليه خمس stable isotopes والـ\natomic mass بتاعه متوسطهم\nومعظمهم nickel تمانية وخمسين الخفيف فالـ\naverage بيقل عن الـ cobalt شوية\nلو أغلبه nickel ستين يبقى أتقل من الـ\ncobalt ولا أخف\nأتقل لأن الـ average هيبقى قريب من ستين\nالـ atomic mass هو average الـ isotopes\nبتوعه","countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":6},{"id":"chem-s3-en.video-short-te.atomic-radius","kind":"short","version":1,"ord":246,"content_lang":"ar-EG","primary_concept_id":"te.atomic-radius","concepts":[{"concept_id":"te.atomic-radius","role":"primary"}],"title":"Atomic radius: nearly constant","payload":{"title":"Atomic radius: nearly constant","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pass v2, all lines: page.html must add <script> tags for lib/short.js and lib/beats.js (template.html lacks them: YK.band, YK.thinkRing, YK.cueLabel, YK.pill, YK.choice); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; look at stills before render.] Frame 0 complete: a row of six YK.atomDisc (r 62, symbol:false, d-block violet) at y 1000, x 158…922, each inside the same dashed white size ring (r 84); a '+1 proton' YK.pill (44, gold) hops disc to disc L→R (0.6 s per hop, looping from frame 0); YK.band 'One more proton. !{Same size}?' (104) at 0. The pill flashes on cue 'proton'; all rings pulse together on cue 'والحجم'.","tts_text":"كل atom بياخد proton زيادة… والحجم مبيتغيرش تقريبًا؟ إزاي؟","screen_text":"One more proton. Same size?"},{"id":"l2","visual":"Discs morph into YK.chart bars (108, 640, 864, 800) Cr 1.17, Mn 1.17, Fe 1.16, Co 1.16, Ni 1.15, Cu 1.17 (book table p.12; ONLY Cr→Cu: Sc/Ti/V are kept back for the check), yLabel 'Atomic radius', yRange [0, 1.5], grow from cue 'chromium' to cue 'copper'; a flat gold line across the tops + label 'nearly constant' (52) on cue 'ثابت'; footnote 'Book table p.12, for illustration only' (40, 60%). Prereq chip 'Atomic radius trend' at line start.","tts_text":"من الـ chromium للـ copper، الـ atomic radius تقريبًا ثابت.","screen_text":"Cr → Cu: nearly constant radius"},{"id":"l3","visual":"Myth (top misconception, R11): small coral ghost bars (60% alpha, no values) sloping steeply down over the chart on cue 'بيصغر' + small tag 'period 3' (44) on cue 'period'; YK.wrongMark on cue 'لأ', ghost gone 0.4 s later; the real flat bars stay, bigger and longer.","tts_text":"ناس فاكرة إنه بيصغر جامد زي الـ period التالت… لأ.","screen_text":"Falls sharply, as across period 3 ✕"},{"id":"l4","visual":"Chart exits. YK.tug(ctx, 540, 1060, 260, {el:'Fe', pull: YK.prog(t, cue 'effective', +0.8), push:0, labels:{pull:'effective nuclear charge', push:''}, t}) — kit colours: inward arrows VIOLET (pull), outward CYAN (push); the dashed ring (r·(1+0.12(push−pull))) shrinks as pull grows, visibly on cue 'يصغر' (ease the pull in from 'effective' to 'يصغر'). YK.pill 'Factor 1' (44) at y 1560. Book p.12 factor a. New term 1.","tts_text":"الأول: الـ effective nuclear charge بتزيد، فبتشد الـ electrons لجوه، والـ radius يصغر.","screen_text":"Factor 1: effective nuclear charge ↑ → radius ↓"},{"id":"l5","visual":"Same tug: push 0→1 from cue 'repulsion' (cyan outward arrows), labels.push '3d repulsion'; the ring grows back on cue 'يكبر'. YK.pill 'Factor 2' (44) replaces 'Factor 1'. Prereq chip 'Electronic configuration of the first transition series' at line start. Book p.13 factor b. New term 2.","tts_text":"التاني: الـ repulsion بين electrons الـ three d بتزيد، فالـ radius يكبر.","screen_text":"Factor 2: more 3d electrons → repulsion ↑ → radius ↑"},{"id":"l6","visual":"Aha hold >= 1.5 s: pull = push = 1, the ring steady at its start radius, both arrow sets pulsing together on cue 'بيتعادلوا'; label 'nearly constant' (56, gold) under the tug on cue 'ثابت'. No balance prop (the tug already shows the two factors).","tts_text":"الـ opposite factors بيتعادلوا، فالـ radius ثابت تقريبًا.","screen_text":"Two opposite factors balance → nearly constant"},{"id":"l7","style":"curious","visual":"New-case check (book table p.12 rows Sc–V never shown). Tug fades. Three rows top→bottom (y 760 / 990 / 1220): YK.atomDisc (r 80, equal placeholder size, label 'Sc' / 'Ti' / 'V') at x 220 on cues 'scandium' (Sc), then Ti, then 'vanadium' (V); next to each at x 640 a YK.electronBoxes 3d row (size 84, labelPos 'none') with 1 / 2 / 3 electrons, all on cue 'three'. YK.band 'Sc → V: what does the radius do?' (72) on cue 'scandium'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no size change before YK.cue('l8').","tts_text":"من الـ scandium للـ vanadium، الـ three d شبه فاضية… الـ radius يعمل إيه؟","screen_text":"Sc → V: what does the radius do?","pause_after_s":2},{"id":"l8","visual":"Answer: the three discs shrink to scale (r = 80 × value / 1.44) with YK.label '1.44', '1.32', '1.22' (mono 48, book p.12) on cue 'بيصغر'; small violet inward arrows glow around each disc on cue 'الشد'; ONE YK.rightMark.","tts_text":"بيصغر، لأن الشد لسه هو الأقوى.","screen_text":"Falls: 1.44 → 1.32 → 1.22 ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Atomic radius: nearly constant', line:'Two opposite factors: a nearly constant radius', t, pulse:[{word:'constant', at:YK.cue('l9','ثابت')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 row of discs.","tts_text":"اتنين opposite factors، يبقى الـ radius ثابت تقريبًا.","screen_text":"Two opposite factors: a nearly constant radius","pause_after_s":1.5}],"logline":"Each atom from Cr to Cu gains a proton, yet the atomic radius stays nearly constant: the rising effective nuclear charge pulls electrons in while the growing repulsion between 3d electrons pushes them out, and the two opposite factors balance (book 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bubbles:0} calm, tag 'Cu' (48); YK.band 'Same series. So !{different}?' (104) at 0. Left beaker flashRect on cue 'scandium', right on cue 'copper'.","tts_text":"الـ scandium بيتفاعل مع المية جامد، والـ copper لأ… ليه؟","screen_text":"Same series. So different?"},{"id":"l2","visual":"Beakers exit; a 2×5 grid of blank metal tiles (steel gradient, no symbols, 150 px, y 820 / 1000) = the ten elements Sc→Zn of the series; tag 'solid' (52) on cue 'solid'; a white shine sweep crosses every tile on cue 'metallic' + tag 'metallic luster' (52). Prereq chip 'Elements of the first transition series' at line start. Book p.13 point 3a. New term 1 (metallic luster).","tts_text":"الأول اللي بيجمعهم: كلهم solid، وليهم metallic luster كمان.","screen_text":"All: solid, with metallic luster"},{"id":"l3","visual":"Below the grid (y 1300): YK.icon 'cable' (160, cyan) with a cyan pulse running along it (left, x 320) and a heat-shimmer wave over the tiles (right, x 760), both on cue 'good'; tag 'good conductors' (52) on cue 'conductors'.","tts_text":"وكلهم good conductors للكهربا والحرارة.","screen_text":"Good conductors"},{"id":"l4","visual":"Tiles fly out; a vertical 'chemical activity' axis arrow (x 200, y 640→1600, label rotated) draws on cue 'chemical'; three empty slots (high / middle / low, y 780 / 1100 / 1420) pulse on cue 'بتختلف'. Prereq chip 'Chemical activity series of metals' at line start.","tts_text":"لكن الـ chemical activity بتختلف من واحد للتاني.","screen_text":"But their chemical activity varies"},{"id":"l5","visual":"Top slot (y 780): the Sc beaker returns small (w 200) at x 560, fizzing; YK.molecule H2 (r 30) bubbles rise on cue 'hydrogen'; tag 'highly active' (coral, 48) at x 800 on cue 'highly'. Book p.13 point 3d.","tts_text":"الـ scandium عنصر highly active: بياخد مكان الـ hydrogen بتاع المية.","screen_text":"Sc: highly active (replaces hydrogen of water)"},{"id":"l6","visual":"Middle slot (y 1100): an iron bar (C.atomFe) at x 560 with orange-brown rust spots spreading (YK.rng seeded) on cue 'بيصدّي'; tag 'moderate' (amber, 48) on cue 'moderate'.","tts_text":"والـ iron نشاطه moderate، بيصدّي في الهوا.","screen_text":"Fe: moderate"},{"id":"l7","visual":"Bottom slot (y 1420): the Cu beaker (w 200), calm water, no bubbles; tag 'limited' (cyan, 48) on cue 'limited'.","tts_text":"والـ copper نشاطه limited، المية مبتعملّوش حاجة.","screen_text":"Cu: limited"},{"id":"l8","visual":"Myth (top misconception, R11): small coral pill 'All like Cu?' (44) slides over the axis on cue 'copper' + YK.wrongMark on cue 'غلطان', gone 0.4 s later; then the three tags (highly active / moderate / limited) pulse in turn top→bottom, bigger and longer on screen.","tts_text":"فاللي فاكر إنهم كلهم زي الـ copper… غلطان.","screen_text":"All unreactive, like copper? ✕"},{"id":"l9","style":"curious","visual":"New-case check (Mn was not one of the book's three activity examples and was never named). Axis dims 35%; one blank metal tile tagged 'Mn' (64) centre (y 1000) on cue 'manganese'; the shine sweep is held back; YK.band 'Mn: metallic luster for sure?' (72) on cue 'metallic'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l9'), end: YK.cue('l10')}) through the stitched silence (pause_after_s 2.0); no shine before YK.cue('l10').","tts_text":"والـ manganese؟ ليه metallic luster أكيد… ولا دي بتختلف؟","screen_text":"Mn: metallic luster for sure, or does it vary?","pause_after_s":2},{"id":"l10","visual":"Answer: shine sweep crosses the Mn tile + ONE YK.rightMark on cue 'أكيد'; the activity axis with its three tags brightens on cue 'activity'.","tts_text":"أكيد، دي مشتركة… اللي بيختلف هو الـ activity بس.","screen_text":"Yes: shared by all ✓"},{"id":"l11","visual":"Voiced lock-in: YK.takeaway({title:'The metallic property', line:'Same metallic look, different activity', t, pulse:[{word:'metallic', at:YK.cue('l11','metallic')}, {word:'activity', at:YK.cue('l11','activity')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 beakers.","tts_text":"نفس الشكل الـ metallic، والـ activity مختلفة.","screen_text":"Same metallic look, different activity","pause_after_s":1.5}],"logline":"All first-series transition elements are solids with metallic luster and good conductivity, but their chemical activity varies: scandium is highly active (replaces the hydrogen of water), iron moderate (rusts in air), copper limited (book 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scandium بيتفاعل مع المية جامد والـ\ncopper لأ ليه\nالأول اللي بيجمعهم كلهم solid وليهم\nmetallic luster كمان\nوكلهم good conductors للكهربا والحرارة\nلكن الـ chemical activity بتختلف من واحد\nللتاني\nالـ scandium عنصر highly active بياخد مكان\nالـ hydrogen بتاع المية\nوالـ iron نشاطه moderate بيصدّي في الهوا\nوالـ copper نشاطه limited المية مبتعملّوش\nحاجة\nفاللي فاكر إنهم كلهم زي الـ copper غلطان\nوالـ manganese ليه metallic luster أكيد\nولا دي بتختلف\nأكيد دي مشتركة اللي بيختلف هو الـ activity\nبس\nنفس الشكل الـ metallic والـ activity\nمختلفة","countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":8},{"id":"chem-s3-en.video-short-phys.states-melting-boiling","kind":"short","version":1,"ord":250,"content_lang":"ar-EG","primary_concept_id":"phys.states-melting-boiling","concepts":[{"concept_id":"phys.states-melting-boiling","role":"primary"}],"title":"States of matter, melting and boiling points","payload":{"title":"States of matter, melting and boiling points","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pass v2, all lines: page.html must add <script> tags for lib/short.js and lib/beats.js (template.html lacks them: YK.band, YK.thinkRing, YK.cueLabel, YK.pill, YK.choice); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; look at stills before render.] Frame 0 complete: a steel pan (rounded rect, side view, y 1100) over a warm glow; a butter block already melting into a spreading puddle (continuous from t=0); YK.band 'Butter melts. !{The pan doesn't.}' (96) at 0. Butter drips faster on cue 'بتسيح'; the pan rim glints on cue 'والطاسة'.","tts_text":"الزبدة بتسيح في الطاسة… والطاسة نفسها لأ. ليه؟","screen_text":"Butter melts. The pan doesn't."},{"id":"l2","visual":"Pan exits; three particle boxes stacked top→bottom (x 300–972, y 640–900 / 960–1220 / 1280–1540): solid = YK.lattice (rows 3, cols 6, packed); liquid = 16 YK.dot moving with YK.swarm (amp 18, touching); gas = 6 YK.dot fast and far apart (YK.swarm amp 90, speed 3) — YK.lattice cannot draw liquid/gas. English labels (52) at x 108 on cues 'solid', 'liquid', 'gas'. Prereq chip 'Matter is made of atoms and molecules' at line start.","tts_text":"المادة بتبقى solid أو liquid أو gas، تلات حالات.","screen_text":"Solid · Liquid · Gas"},{"id":"l3","visual":"One box centre (y 1000) in the solid pattern; a thermometer at x 200; the lattice loosens into the liquid swarm on cue 'بيبقى'; tick '0 °C' (YK.label mono 48) lights on cue 'صفر'; label 'Melting point' (56) on cue 'melting'. New term 1.","tts_text":"الـ melting point: عندها الـ solid بيبقى liquid، زي التلج عند صفر.","screen_text":"Melting point: solid → liquid (ice: 0 °C)"},{"id":"l4","visual":"Same box: the liquid dots fly apart into the gas pattern on cue 'gas'; bubbles rise on cue 'وبيغلي'; label 'Boiling point' (56) on cue 'boiling'. New term 2.","tts_text":"والـ boiling point: عندها الـ liquid بيبقى gas وبيغلي.","screen_text":"Boiling point: liquid → gas"},{"id":"l5","visual":"Two small YK.lattice (3×3) side by side (x 300 / 780, y 1000) with custom link lines drawn between neighbouring lattice.pos() points (lattice has no links): thin dashed (left) vs thick solid gold (right), the right ones thicken on cue 'أقوى'; a thermometer bar under each, the right one rises higher on cue 'بيعلى'.","tts_text":"وكل ما الـ particles ماسكة في بعض أقوى، الـ melting point بيعلى.","screen_text":"Stronger hold between particles → higher melting point"},{"id":"l6","visual":"Aha hold >= 1.5 s: the pan returns; inset circles zoom into the butter (dashed weak links) on cue 'الزبدة' and into the pan wall (thick metal links) on cue 'جامد'; labels 'weak hold' / 'strong hold' (48).","tts_text":"الزبدة ماسكة ضعيف، لكن الـ particles في معدن الطاسة ماسكة جامد.","screen_text":"Butter: weak hold · Pan metal: strong hold"},{"id":"l7","style":"curious","visual":"New-case check (book table p.12 values; no metal compared before). Two tiles 'Ti' / 'Cu' (x 320 / 760) with thermometers reading '1680 °C' / '1083 °C' (YK.label mono 48) on cues 'titanium' / 'copper'; YK.band 'Which holds stronger?' (80) on cue 'ماسك'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no links drawn before YK.cue('l8').","tts_text":"الـ titanium بيسيح عند حرارة أعلى من الـ copper بكتير… مين ماسك أقوى؟","screen_text":"Ti 1680 °C, Cu 1083 °C. Which holds stronger?","pause_after_s":2},{"id":"l8","visual":"Answer: a thick-link lattice fills the Ti tile + ONE YK.rightMark on cue 'titanium'; the Ti thermometer glows on cue 'أعلى'.","tts_text":"الـ titanium، عشان الـ melting point بتاعه أعلى.","screen_text":"Titanium: stronger hold ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'States of matter, melting and boiling points', line:'Stronger hold, higher melting point', t, pulse:[{word:'melting', at:YK.cue('l9','melting')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 pan.","tts_text":"مسكة أقوى، يعني melting point أعلى.","screen_text":"Stronger hold, higher melting point","pause_after_s":1.5}],"logline":"Matter is solid, liquid or gas; the melting point and boiling point are the temperatures where it changes state, and the more strongly its particles hold each other, the higher the melting point: why titanium (1680 °C) melts far above copper (1083 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Two ways. !{Which}?' (104) at 0. Both pairs pulse on cue 'طريقتين'.","tts_text":"الـ atoms بتمسك في بعض إزاي؟ فيه طريقتين أساسيتين.","screen_text":"Atoms bond. Two main ways. Which?"},{"id":"l2","visual":"Top pair grows: YK.atom(ctx, 300, 1000, {shells:[2,8,1], size:200}) Na and YK.atom(ctx, 780, 1000, {shells:[2,8,7], size:200}) Cl (rotate 0); Na's outer electron (YK.dot) flies on an arc into Cl's outer shell on cue 'electron'; charge labels YK.label 'Na^+' / 'Cl^-' (56) on cue 'ions'. Prereq chip 'Ions (cations and anions)' at line start.","tts_text":"الـ sodium بيدي electron للـ chlorine، فالاتنين بيبقوا ions مشحونة.","screen_text":"Na gives one electron to Cl"},{"id":"l3","visual":"Gold attraction lines between Na⁺ and Cl⁻; the ions slide together on cue 'بيشدوا'; label 'Ionic bond' (64) on cue 'ionic'. New term 1.","tts_text":"الموجب والسالب بيشدوا بعض، وده الـ ionic bond بينهم.","screen_text":"Ionic bond: + and − attract"},{"id":"l4","visual":"Ions exit; the Cl + Cl pair grows (two YK.atom shells [2,8,7], size 190, outer shells overlapping at x 540); an outer electron starts to hop and springs back on cue 'محدش'; two gold dots settle in the overlap on cue 'فبيشاركوا'.","tts_text":"لكن اتنين chlorine؟ محدش بيدي، فبيشاركوا في زوج electrons بينهم.","screen_text":"Cl + Cl: neither gives"},{"id":"l5","visual":"Gold ellipse around the shared pair; label 'Covalent bond' (64) on cue 'covalent'; formula 'Cl_2' (YK.formula mono 64) under it. New term 2.","tts_text":"وده الـ covalent bond: الـ electrons متشاركة بين الاتنين.","screen_text":"Covalent bond: a shared electron pair"},{"id":"l6","style":"curious","visual":"New-case check (lesson used MgO, KBr, H₂O, CH₄, O₂). Two YK.atomDisc 'Li' / 'F' (r 90, x 320 / 760, y 1000) on cues 'lithium' / 'fluorine'; YK.choice 'ionic' / 'covalent' (y 1300) on cues 'ionic' / 'covalent'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l6'), end: YK.cue('l7')}) through the stitched silence (pause_after_s 2.0); no electron moves before YK.cue('l7').","tts_text":"الـ lithium مع الـ fluorine: ionic ولا covalent يا ترى؟","screen_text":"Lithium + fluorine: ionic or covalent?","pause_after_s":2},{"id":"l7","visual":"Answer: 'ionic' choice glows mint (covalent dims) + ONE YK.rightMark on cue 'ionic'; an electron hops Li → F on cue 'electron', charge badges (atomDisc charge '+' / '−').","tts_text":"هيبقى ionic، الـ lithium metal بيدي electron بسهولة.","screen_text":"Ionic: Li gives one electron to F ✓"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'Ionic and covalent bonds', line:'Ionic: give and take. Covalent: share.', t, pulse:[{word:'Ionic', at:YK.cue('l8','ionic')}, {word:'Covalent', at:YK.cue('l8','covalent')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ ionic تدي، والـ covalent تشارك.","screen_text":"Ionic: give and take. Covalent: share.","pause_after_s":1.5}],"logline":"Atoms bond in two ways: sodium gives an electron to chlorine and the oppositely charged ions attract (ionic bond), while two chlorine atoms share a pair of electrons (covalent 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(96) at 0. Two small text-free icons at y 1500 (an electron hopping between two discs; two discs sharing a dot pair) each get a small YK.wrongMark on cues 'بتدي' and 'بتشارك'. Prereq chip 'Ionic and covalent bonds' on cue 'بتشارك' (after the hook's first 2 s).","tts_text":"الـ metal atoms مش بتدي لبعض ولا بتشارك زوج… أومال ماسكين إزاي؟","screen_text":"Metal atoms: how do they hold?"},{"id":"l2","visual":"Each atom releases dots: lattice sea:{count:24, t, seed:3} fades in on cue 'valence' + label 'valence electrons' (48); the dots start drifting between the atoms on cue 'بحرية'.","tts_text":"كل atom بيسيب الـ valence electrons بتوعه يتحركوا بحرية.","screen_text":"Valence electrons move freely"},{"id":"l3","visual":"lattice charge:'+' badges appear on every atom on cue 'positive'; the sea glows cyan on cue 'بحر'.","tts_text":"فيفضل positive ion، وسط بحر من الـ electrons الحرة.","screen_text":"Positive ions + electrons"},{"id":"l4","visual":"Gold attraction flickers between ions and nearby dots on cue 'الشد'; label 'Metallic bond' (64) on cue 'metallic'. New term 1.","tts_text":"الشد ده بين الـ ions والـ electrons هو الـ metallic bond بالظبط.","screen_text":"Metallic bond: ions held by the electrons"},{"id":"l5","visual":"Two small YK.lattice (3×3) side by side (x 140–500 / 580–940, y 900): Na with sea count 9 (1 per atom) on cue 'sodium', Mg with sea count 18 (2 per atom, denser) on cue 'magnesium'; Mg custom link lines thicken on cue 'أقوى'; thermometers '98 °C' / '650 °C' (YK.label mono 48) rise under them on cue 'وبيسيح'. Approved lesson values.","tts_text":"الـ sodium بيدي واحد، والـ magnesium اتنين… فالـ bond أقوى، وبيسيح أعلى.","screen_text":"Na: 1 → 98 °C · Mg: 2 → 650 °C"},{"id":"l6","style":"curious","visual":"New-case check (lesson used K/Ca and Na/Mg/Al). Two tiles 'Li' / 'Be' (x 320 / 760) on cues 'lithium' / 'beryllium', each a 2×2 mini lattice with 1 and 2 sea dots per atom; thermometers hidden ('?'). YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l6'), end: YK.cue('l7')}) through the stitched silence (pause_after_s 2.0); nothing rises before YK.cue('l7').","tts_text":"الـ lithium بيدي electron، والـ beryllium اتنين… مين يسيح أعلى؟","screen_text":"Li gives 1 electron, Be gives 2. Which melts higher?","pause_after_s":2},{"id":"l7","visual":"Answer: the Be lattice links thicken + ONE YK.rightMark on cue 'beryllium'; its thermometer rises above Li's on cue 'أقوى' (no values).","tts_text":"الـ beryllium، الـ bond بتاعه أقوى.","screen_text":"Beryllium: stronger bond ✓"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'Metallic bond', line:'More free electrons, stronger metallic bond', t, pulse:[{word:'metallic', at:YK.cue('l8','metallic')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"أكتر electrons حرة، يبقى metallic bond أقوى.","screen_text":"More free electrons, stronger metallic bond","pause_after_s":1.5}],"logline":"Metal atoms neither give electrons to each other nor share pairs: each releases its valence electrons, and the positive ions are held by the free electrons around them; more free electrons per atom (Mg 2 vs Na 1) mean a stronger bond and a higher melting 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metal atoms مش بتدي لبعض ولا بتشارك\nزوج أومال ماسكين إزاي\nكل atom بيسيب الـ valence electrons بتوعه\nيتحركوا بحرية\nفيفضل positive ion وسط بحر من الـ\nelectrons الحرة\nالشد ده بين الـ ions والـ electrons هو الـ\nmetallic bond بالظبط\nالـ sodium بيدي واحد والـ magnesium اتنين\nفالـ bond أقوى وبيسيح أعلى\nالـ lithium بيدي electron والـ beryllium\nاتنين مين يسيح أعلى\nالـ beryllium الـ bond بتاعه أقوى\nأكتر electrons حرة يبقى metallic bond أقوى","countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":11},{"id":"chem-s3-en.video-short-te.high-melting-points","kind":"short","version":1,"ord":256,"content_lang":"ar-EG","primary_concept_id":"te.high-melting-points","concepts":[{"concept_id":"te.high-melting-points","role":"primary"}],"title":"High melting and boiling points","payload":{"title":"High melting and boiling points","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pass v2, all lines: page.html must add <script> tags for lib/short.js and lib/beats.js (template.html lacks them: YK.band, YK.thinkRing, YK.cueLabel, YK.pill, YK.choice); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; look at stills before render.] Frame 0 complete: two thermometers side by side (x 360 / 720, y 760–1560) already rising from t=0: 'Ca' to '842 °C' and 'Cr' to '1890 °C' (YK.label mono 48; Cr book table p.12, Ca approved lesson); YK.band 'Ca 842 °C, Cr !{1890 °C}. Why?' (96) at 0. Cr column glows on cue 'chromium', Ca on cue 'calcium'.","tts_text":"الـ chromium بيسيح عند ضعف حرارة الـ calcium وأكتر… ليه؟","screen_text":"Ca 842 °C, Cr 1890 °C. Why?"},{"id":"l2","visual":"YK.chart(ctx, 108, 640, 864, 820, {type:'bar', data melting points Sc→Cu (book p.12: 1397, 1680, 1710, 1890, 1247, 1538, 1490, 1492, 1083), yLabel:'Melting point (°C)', yRange:[0, 2000]}) bars grow on cue 'melting'; NO second boiling series (two scales = clutter): YK.pill 'boiling points: high too' (44) at y 1540 on cue 'boiling'; footnote 'Book table p.12, for illustration only' (40, 60%). Prereq chip 'Metallic bond' at line start. Book p.13 point 3b.","tts_text":"عناصر السلسلة الأولى ليها melting و boiling points عالية.","screen_text":"High melting and boiling points"},{"id":"l3","visual":"Myth (top misconception, R11): coral pill 'heavy atoms?' (44) + small YK.wrongMark on cue 'لأ', gone 0.4 s later; then chart highlight:['Cr','Cu'] with mass labels 'Cr 52' / 'Cu 63.5' (mono 44) on cue 'copper' and the Cu bar pulses, visibly lower than Cr, on cue 'أقل'.","tts_text":"ناس فاكرة عشان الـ atoms تقيلة… لأ، الـ copper أتقل وبيسيح أقل.","screen_text":"Heavy atoms? ✕  Cu is heavier, melts lower"},{"id":"l4","visual":"Chart exits. Top: YK.configStrip(ctx, 560, 840, {el:'Ca', size:80, tag:true, zeros:false}) ('[Ar] 4s^2', 3d boxes empty; check the still shows no '3d^0') on cue 'calcium', its 4s electrons glow on cue 'four'. Bottom: YK.configStrip(ctx, 560, 1240, {el:'Cr', size:80, tag:true}) (book '[Ar] 4s^1 3d^5') on cue 'chromium'; its 3d electrons glow (unpaired:1 glow, no tag) on cue 'three'. Prereq chip 'Electronic configuration of the first transition series' on cue 'chromium'.","tts_text":"الـ calcium بيبني بالـ four s بس، والـ chromium بالـ three d كمان.","screen_text":"Ca: 4s only · Cr: 4s and 3d"},{"id":"l5","visual":"Two small YK.lattice (3×3) side by side: Ca (sparse sea) vs Cr (dense sea) on cue 'electrons'; Cr custom links thicken on cue 'أقوى'; a Cr thermometer rises on cue 'أعلى'. No electron count claimed per atom.","tts_text":"يعني electrons أكتر، metallic bond أقوى، و melting point أعلى.","screen_text":"More bonding electrons → higher melting point"},{"id":"l6","style":"curious","visual":"New-case check (lesson used Ca vs Ti and Ca vs Sc). Two YK.configStrip rows (size 80, tag:true): K (Z 19, '[Ar] 4s^1') at y 840 on cue 'potassium'; V ('[Ar] 4s^2 3d^3') at y 1200 on cue 'vanadium' (3d boxes flash on cue 'three'); a grey '?' pill under each. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l6'), end: YK.cue('l7')}) through the stitched silence (pause_after_s 2.0); no value before YK.cue('l7').","tts_text":"الـ potassium عنده four s بس، والـ vanadium فيه three d… مين يسيح أعلى؟","screen_text":"K: [Ar] 4s¹ · V: [Ar] 4s² 3d³. Which melts higher?","pause_after_s":2},{"id":"l7","visual":"Answer: V's '?' becomes '1710 °C' (YK.label mono 52, book p.12) + ONE YK.rightMark on cue 'vanadium'; V's 3d electrons glow gold (unpaired:1) and small dots drift off into a sea on cue 'three'.","tts_text":"الـ vanadium، لأن الـ three d بتدخل في الـ bond معاها.","screen_text":"V: 4s and 3d bond (1710 °C) ✓"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'High melting and boiling points', line:'3d shares too: strong metallic bond', t, pulse:[{word:'3d', at:YK.cue('l8','three')}, {word:'strong', at:YK.cue('l8','قوي')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ three d بتشارك كمان: metallic bond قوي.","screen_text":"3d shares too: strong metallic bond","pause_after_s":1.5}],"logline":"Chromium melts at 1890 °C, more than twice calcium's 842 °C: in the transition elements both 4s and 3d electrons share in a strong metallic bond, while calcium bonds with its 4s electrons only; heavy atoms are not the reason (Cu is heavier than Cr but melts lower; book 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Why is !{iron} heavier?' (96) at 0. Al cube glows on cue 'aluminum', Fe cube on cue 'iron'. (No chip in the hook.)","tts_text":"مكعبين نفس الحجم بالظبط، واحد aluminum وواحد iron… ليه الـ iron أتقل؟","screen_text":"Same size. Why is iron heavier?"},{"id":"l2","visual":"Balance slides down to y 1450 (small); YK.formula 'density = mass ÷ volume' (72, y 820) builds word by word on cues 'density', 'mass', 'volume'; unit tag 'g/cm^3' (48) under it. Prereq chip 'Mass and volume' at line start. New term 1.","tts_text":"الـ density: الـ mass مقسومة على الـ volume، ببساطة كده.","screen_text":"Density = mass ÷ volume (g/cm³)"},{"id":"l3","visual":"Each cube gets its value: 'Fe 7.87 g/cm^3' on cue 'iron' (book table p.12), 'Al 2.7 g/cm^3' on cue 'aluminum' (YK.label, mono 52).","tts_text":"الـ iron سبعة فاصل سبعة وتمانين، والـ aluminum اتنين فاصل سبعة بس.","screen_text":"Iron 7.87 g/cm³ · Aluminum 2.7 g/cm³"},{"id":"l4","visual":"Aha hold >= 1.5 s: both cubes turn see-through showing the same number of particle slots (same particle size in both); the Fe particles turn darker with a small weight tick (heavier, NOT bigger) on cue 'mass'; a gold arrow + 'higher density' (52) on cue 'density'.","tts_text":"نفس الـ volume، بس mass أكتر… يبقى density أعلى.","screen_text":"Same volume, more mass → higher density"},{"id":"l5","style":"curious","visual":"New-case check (lesson worked 27/10 and 39.5/5). A new copper-coloured block, no name, with tags '10 cm^3' on cue 'volume' and '89.2 g' on cue 'mass' (YK.label mono 52); YK.band 'Density = ?' (80) on cue 'density'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l5'), end: YK.cue('l6')}) through the stitched silence (pause_after_s 2.0); no number before YK.cue('l6').","tts_text":"حتة الـ volume بتاعها عشرة، والـ mass تسعة وتمانين فاصل اتنين… الـ density كام؟","screen_text":"10 cm³, 89.2 g. Density?","pause_after_s":2},{"id":"l6","visual":"Answer: YK.formula '89.2 ÷ 10 = 8.92 g/cm^3' (mono 60) types out on cue 'تمانية' + ONE YK.rightMark; the block gets the tag 'Cu' on cue 'copper' (book table p.12: Cu 8.92).","tts_text":"تمانية فاصل اتنين وتسعين… نفس density الـ copper بالظبط.","screen_text":"89.2 ÷ 10 = 8.92 g/cm³ ✓"},{"id":"l7","visual":"Voiced lock-in: YK.takeaway({title:'Density', line:'Density = mass ÷ volume', t, pulse:[{word:'Density', at:YK.cue('l7','density')}, {word:'mass', at:YK.cue('l7','mass')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"يعني الـ density: mass على الـ volume كده.","screen_text":"Density = mass ÷ volume","pause_after_s":1.5}],"logline":"Two cubes of the same size, aluminum and iron, have different masses: density is mass divided by volume (g/cm³), so more mass in the same volume means a higher density (iron 7.87, aluminum 2.7 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نفس الحجم بالظبط واحد aluminum\nوواحد iron ليه الـ iron أتقل\nالـ density الـ mass مقسومة على الـ volume\nببساطة كده\nالـ iron سبعة فاصل سبعة وتمانين والـ\naluminum اتنين فاصل سبعة بس\nنفس الـ volume بس mass أكتر يبقى density\nأعلى\nحتة الـ volume بتاعها عشرة والـ mass تسعة\nوتمانين فاصل اتنين الـ density كام\nتمانية فاصل اتنين وتسعين نفس density الـ\ncopper بالظبط\nيعني الـ density mass على الـ volume كده","countable":true,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":13},{"id":"chem-s3-en.video-short-te.density-trend","kind":"short","version":1,"ord":260,"content_lang":"ar-EG","primary_concept_id":"te.density-trend","concepts":[{"concept_id":"te.density-trend","role":"primary"}],"title":"Density increases with atomic number","payload":{"title":"Density increases with atomic number","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pass v2, all lines: page.html must add <script> tags for lib/short.js and lib/beats.js (template.html lacks them: YK.band, YK.thinkRing, YK.cueLabel, YK.pill, YK.choice); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; look at stills before render.] Frame 0 complete: two equal cubes 'Mn' / 'Fe' on YK.balance(ctx, 540, 1250, 640, {left:'Mn', right:'Fe', value:0.4}) (Fe side down); above each a magnified YK.atomDisc of equal radius (r 90, y 820) labelled 'r 1.17' / 'r 1.16' (mono 40, book p.12); YK.band 'Same-size atoms. Why is !{Fe} denser?' (96) at 0. Fe glows on cue 'iron', Mn on cue 'manganese', the two discs pulse together on cue 'حجم'.","tts_text":"ليه الـ iron أتقل، والـ atoms نفس حجم الـ manganese تقريبًا؟","screen_text":"Same-size atoms. Why is Fe denser?"},{"id":"l2","visual":"YK.chart(ctx, 108, 640, 864, 820, {type:'bar', categories Sc→Cu, yLabel:'Density (g/cm^3)', yRange:[0, 10]}): bars Sc→Fe (book p.12: 3.10, 4.42, 6.07, 7.19, 7.21, 7.87) grow L→R from cue 'density' to cue 'number'; Co, Ni, Cu are dashed empty slots with a grey '?' (data y 0 + custom dashed rect at px()) — kept back for the check; footnote 'Book table p.12, for illustration only' (40, 60%). Prereq chip 'Density' at line start. Book p.13 point 3c.","tts_text":"الـ density هنا بتزيد مع الـ atomic number، ومعظمهم عالية.","screen_text":"Density increases with atomic number"},{"id":"l3","visual":"Chart dims; two cubes (Mn left, Fe right, y 1000) show their atoms; the atoms take a darker shade (heavier) on cue 'mass'; tags 'Mn 54.9' / 'Fe 55.9' (mono 44). Prereq chip 'Atomic mass: why nickel is abnormal' at line start.","tts_text":"ليه؟ الـ atomic mass بتزيد بالتدريج على طول السلسلة.","screen_text":"Atomic mass increases"},{"id":"l4","visual":"Dashed equal-size rings lock around the atoms in both cubes on cue 'size'; label 'nearly constant' (52) on cue 'ثابت'. Prereq chip 'Atomic radius: nearly constant' at line start.","tts_text":"لكن الـ atomic size تقريبًا ثابت، مبيصغرش كتير.","screen_text":"Atomic size: nearly constant"},{"id":"l5","visual":"Aha hold >= 1.5 s: the Fe cube sinks on the balance on cue 'mass'; the cube outline flashes (same size) on cue 'volume'; gold arrow 'density ↑' on cue 'density'.","tts_text":"يعني mass أكتر في نفس الـ volume تقريبًا… فالـ density بتزيد.","screen_text":"More mass, same volume → density ↑"},{"id":"l6","visual":"Myth (top misconception, R11): small coral ghost of shrinking atoms (60% alpha) on cue 'بتصغر' + small YK.wrongMark, gone 0.4 s later; the equal rings pulse mint + ONE YK.rightMark on cue 'size'.","tts_text":"مش عشان الـ atoms بتصغر جامد… الـ size تقريبًا هو هو.","screen_text":"Atoms get much smaller? ✕  Size nearly constant ✓"},{"id":"l7","style":"curious","visual":"New-case check (Co/Cu densities were kept out of the l2 chart; lesson used Cr vs Cu and an X/Y pair). Two tiles 'Co' / 'Cu' (x 320 / 760) with tags 'mass 58.9 · r 1.16' / 'mass 63.5 · r 1.17' (mono 44, book p.12) on cues 'cobalt' / 'copper'; equal dashed rings on cue 'radius'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no density before YK.cue('l8').","tts_text":"الـ cobalt والـ copper نفس الـ radius تقريبًا… مين الـ density بتاعته أعلى؟","screen_text":"Co and Cu: same radius. Which is denser?","pause_after_s":2},{"id":"l8","visual":"Answer: density tags 'Cu 8.92' / 'Co 8.70' (mono 52, book p.12) fade in, Cu glows + ONE YK.rightMark on cue 'copper'; the chart's Co and Cu slots fill (Ni stays '?').","tts_text":"الـ copper، mass أكبر بكتير في نفس الحجم تقريبًا.","screen_text":"Cu: 8.92 > Co: 8.70 ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Density increases with atomic number', line:'Same size, more mass: higher density', t, pulse:[{word:'size', at:YK.cue('l9','size')}, {word:'mass', at:YK.cue('l9','mass')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"نفس الـ size و mass أكتر: density أعلى.","screen_text":"Same size, more mass: higher density","pause_after_s":1.5}],"logline":"Iron's atoms are about the size of manganese's, yet iron is denser: across the first transition series the atomic mass increases while the atomic size stays relatively constant, so more mass sits in about the same volume and density rises with atomic number (book 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pull:1, dir:+1} swung in toward the magnet, right from x 780 {unpaired:0, pull:1, dir:-1} nudged away (outward); YK.band 'Pulled in or !{pushed out}?' (104) at 0. Left tube flashRect on cue 'بتتشد', right on cue 'بتتزق'. Prereq chip 'Magnets and magnetic fields' on cue 'بتتزق' (after the first 2 s).","tts_text":"نفس الـ magnet: مادة بتتشد ليه، ومادة بتتزق بعيد… ليه؟","screen_text":"Pulled in or pushed out?"},{"id":"l2","visual":"Zoom into one electron (y 1050): YK.spinArrow ↑ (the glyph, 120 px) inside a custom circular arrow that turns around it (YK.spinArrow itself does not rotate) on cue 'بيلف'; dashed field loops grow around it on cue 'magnetic'. Prereq chip \"Hund's rule and orbital-box diagrams\" on cue 'unpaired'. Book p.13.","tts_text":"الـ unpaired electron وهو بيلف حوالين نفسه بيعمل magnetic field صغير.","screen_text":"Spinning unpaired electron → magnetic field"},{"id":"l3","visual":"Back to the magnet and the left tube; YK.electronBoxes 3d (size 80) at (540, 1540), electrons ['↑↓','↑','↑','↑','↑'], highlight:[1,2,3,4] (gold boxes mark the unpaired; arrows stay kit cyan/pink); custom tag 'paramagnetic' (52, gold) under the left tube on cue 'paramagnetic' (kit tag stays off); the tube swings further in on cue 'وبتتشد'. New term 1.","tts_text":"المادة اللي فيها unpaired electrons اسمها paramagnetic، وبتتشد ناحيته.","screen_text":"Paramagnetic: unpaired electrons → attracted"},{"id":"l4","visual":"New shot: YK.momentMeter(ctx, 540, 900, 200, {value: 5 × fill, max:5}) with title 'magnetic moment' (48) above it on cue 'magnetic'; YK.electronBoxes 3d row (size 96, y 1350, electrons:5, fill 0→1 from cue 'تزيد' to cue 'بيكبر', Hund order); the needle tracks the number of ↑ placed. New term 2.","tts_text":"وكل ما الـ unpaired electrons تزيد، الـ magnetic moment بيكبر.","screen_text":"More unpaired electrons → larger magnetic moment"},{"id":"l5","visual":"Same boxes: electrons:10, the five ↓ arrive (fill continues) on cue 'paired'; needle drops to 0 on cue 'بصفر'; cut back to the magnet: the right tube pushed away + custom tag 'diamagnetic' (52, cyan) on cue 'diamagnetic'. New term 3. Book p.14.","tts_text":"ولو كل الـ electrons paired، الـ moment بصفر، والمادة diamagnetic بتتزق بعيد.","screen_text":"Diamagnetic: all paired → moment 0, repelled"},{"id":"l6","visual":"Myth = TOP misconception (R11 short: 'Paramagnetic means a permanent magnet'), written for the tts fix below. Left (paramagnetic) tube only: the magnet slides out of frame (p 1→0) and the tube hangs straight (pull 0); small coral pill 'A magnet itself?' (44) on cue 'نفسه' + small YK.wrongMark on cue 'لأ', gone 0.4 s later; the magnet slides back, the tube swings in (pull 0→1) + label 'attracted only in a field' (52, mint) + ONE YK.rightMark on cue 'بيتشد'. If the scriptwriter keeps the diamagnetic myth instead, R11 caps it: do not render this line until the tts is settled.","tts_text":"ناس فاكرة الـ paramagnetic magnet في نفسه… لأ، بيتشد جوه الـ magnetic field بس.","screen_text":"A magnet itself? ✕  Attracted only in a field ✓"},{"id":"l7","style":"curious","visual":"New-case check (Cu⁺: book lists +1 for Cu; the lesson used Zn, Ni²⁺, Fe²⁺). The magnet stays; a new tube {unpaired:0, pull:0, tag:false, label:'Cu^+'} from x 300 on cue 'copper'; YK.label '3d^10' (mono 64) beside it on cue 'three'; the tube hangs still. YK.thinkRing(ctx, t, 540, 1540, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no swing before YK.cue('l8').","tts_text":"الـ copper one plus، الـ three d فيها عشرة… هيتشد ولا هيتزق؟","screen_text":"Cu⁺: 3d¹⁰. Attracted or repelled?","pause_after_s":2},{"id":"l8","visual":"Answer: 3d boxes ['↑↓'×5] (size 80) under the label on cue 'paired'; the tube's pull 0→1 (pushed out) + tag:true now ('diamagnetic', kit) + ONE YK.rightMark on cue 'هيتزق'.","tts_text":"هيتزق، كله paired، يعني diamagnetic خالص.","screen_text":"Repelled: all paired → diamagnetic ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Paramagnetic and diamagnetic substances', line:'Unpaired: attracted · All paired: repelled', t, pulse:[{word:'Unpaired', at:YK.cue('l9','يتشد')}, {word:'paired', at:YK.cue('l9','يتزق')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"فيه unpaired يتشد، كله paired يتزق.","screen_text":"Unpaired: attracted · All paired: repelled","pause_after_s":1.5}],"logline":"A spinning unpaired electron makes a small magnetic field: a substance with unpaired electrons is paramagnetic (attracted to an external magnetic field, its magnetic moment rising with the number of unpaired electrons); one with all electrons paired is diamagnetic (moment zero, repelled) (book 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الـ magnet مادة بتتشد ليه ومادة بتتزق\nبعيد ليه\nالـ unpaired electron وهو بيلف حوالين نفسه\nبيعمل magnetic field صغير\nالمادة اللي فيها unpaired electrons اسمها\nparamagnetic وبتتشد ناحيته\nوكل ما الـ unpaired electrons تزيد الـ\nmagnetic moment بيكبر\nولو كل الـ electrons paired الـ moment\nبصفر والمادة diamagnetic بتتزق بعيد\nناس فاكرة الـ paramagnetic magnet في نفسه\nلأ بيتشد جوه الـ magnetic field بس\nالـ copper one plus الـ three d فيها عشرة\nهيتشد ولا هيتزق\nهيتزق كله paired يعني diamagnetic خالص\nفيه unpaired يتشد كله paired يتزق","countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":5},{"id":"chem-s3-en.video-short-te.magnetic-moment-from-config","kind":"short","version":1,"ord":293,"content_lang":"ar-EG","primary_concept_id":"te.magnetic-moment-from-config","concepts":[{"concept_id":"te.magnetic-moment-from-config","role":"primary"}],"title":"Unpaired electrons and magnetic moment","payload":{"title":"Unpaired electrons and magnetic moment","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pass v2, all lines: page.html must add <script> tags for lib/short.js and lib/beats.js (template.html lacks them: YK.band, YK.thinkRing, YK.cueLabel, YK.pill, YK.choice); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; look at stills before render.] Frame 0 complete: YK.magneticSample(ctx, 380, 640, {unpaired:5, pull:1, dir:+1, label:'FeCl_3', tag:false, t}) swinging toward YK.magnet(ctx, 840, 820, {type:'horseshoe', size:360, angle:-Math.PI/2 (opening left), field:1, t}); five empty 3d boxes (YK.electronBoxes size 96, electrons:0, y 1350) with a pulsing gold '?'; YK.band 'FeCl_3: how many !{unpaired}?' (96) at 0. The tube label glows on cue 'chloride', the boxes pulse on cue 'unpaired'. No separate 120 px formula (the band and tube already carry it).","tts_text":"في الـ iron three chloride، كام unpaired electron عند الـ iron هنا؟","screen_text":"FeCl₃: how many unpaired electrons?"},{"id":"l2","visual":"Sample slides away. Formula 'FeCl_3' (YK.formula mono 96, y 820); step pill 'Step 1' (YK.pill 44) bottom-left (x 108, y 1620) on cue 'خطوة' — no YK.flow rail (too narrow, a 3rd text block); 'Cl: −1 × 3' (mono 52, y 1000) on cue 'minus'; 'Fe: +3' (mono 64, gold, y 1120) on cue 'تلاتة'. Prereq chip 'Oxidation state in compounds' at line start.","tts_text":"أول خطوة: الـ oxidation state، كل chlorine عليه minus one، فالـ iron تلاتة.","screen_text":"Step 1: Cl −1, so Fe +3"},{"id":"l3","visual":"Step pill → 'Step 2'. YK.configStrip(ctx, 610, 1060, {el:'Fe', size:80, charge:3, remove: YK.prog(t, cue 'بيخسر', +1.5), tag:true}): the two 4s electrons leave first (trails) on cue 'four', then one 3d electron; live label '[Ar] 3d^5' readable on cue 'فيفضل'. Check stills: strip + tag inside x 108–972. Prereq chip 'Ions: 4s electrons are lost first' at line start. Book p.9.","tts_text":"تاني خطوة: الـ iron three plus بيخسر الـ four s، فيفضل three d خمسة.","screen_text":"Step 2: Fe³⁺ = [Ar] 3d⁵"},{"id":"l4","visual":"Step pill → 'Step 3'. Same strip: unpaired 0→1 (kit gold glow on the five ↑ + 'unpaired = 5' tag) from cue 'rule' to cue 'خمسة'; label 'paramagnetic' (52, gold, y 1380) on cue 'paramagnetic'. No moment meter (one idea, fewer blocks). Prereq chip 'Paramagnetic and diamagnetic substances' on cue 'paramagnetic'.","tts_text":"تالت خطوة: بالـ Hund's rule، خمسة unpaired، paramagnetic قوي.","screen_text":"Step 3: 5 unpaired → paramagnetic"},{"id":"l5","visual":"Myth (top misconception, R11): small coral row at y 760: YK.configStrip(ctx, 560, 760, {el:'Fe', size:60, dim:0.3}) + label 'Fe atom: 4 unpaired' (44) on cue 'atom' + small YK.wrongMark on cue 'غلط', gone 0.4 s later; the big Fe³⁺ strip (y 1060) glows mint + label 'Fe^3+ ion: 5 unpaired' (52) + ONE YK.rightMark on cue 'ion'.","tts_text":"العد على الـ atom غلط، الـ ion هو اللي يتعد.","screen_text":"Count the ion, not the atom"},{"id":"l6","style":"curious","visual":"New-case check (lesson worked FeCl₃, Cr₂O₃). Formula 'CoCl_2' (mono 96, y 800) on cue 'chloride'; tag 'Co: +2' (mono 52) on cue 'اتنين'; five empty 3d boxes (size 96, y 1150) with '?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l6'), end: YK.cue('l7')}) through the stitched silence (pause_after_s 2.0); no arrows before YK.cue('l7').","tts_text":"والـ cobalt chloride؟ الـ cobalt هنا oxidation state اتنين… كام unpaired عنده؟","screen_text":"CoCl₂: Co is +2. How many unpaired?","pause_after_s":2},{"id":"l7","visual":"Answer: the boxes become YK.configStrip(ctx, 610, 1150, {el:'Co', size:80, charge:2, remove:1, tag:true}) with live label '[Ar] 3d^7' on cue 'three'; unpaired 0→1 (gold glow on the three single ↑ + 'unpaired = 3') on cue 'تلاتة'; label 'paramagnetic' + ONE YK.rightMark on cue 'paramagnetic'.","tts_text":"الـ cobalt two plus فيه three d سبعة، تلاتة unpaired: paramagnetic كمان.","screen_text":"Co²⁺ = [Ar] 3d⁷: 3 unpaired ✓"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'Unpaired electrons and magnetic moment', line:'Magnetic moment? Count the ion's unpaired.', t, pulse:[{word:'Magnetic', at:YK.cue('l8','magnetic')}, {word:'unpaired', at:YK.cue('l8','unpaired')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ magnetic moment؟ اعدّ unpaired الـ ion نفسه.","screen_text":"Magnetic moment? Count the ion's unpaired.","pause_after_s":1.5}],"logline":"To judge a compound like FeCl₃: find the metal's oxidation state (+3), write the ion's configuration with 4s lost first ([Ar] 3d⁵), fill the 3d boxes by Hund's rule and count the unpaired electrons (5): paramagnetic; count the ion, not the atom (book p.14, 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(stretch 0.1 wobble); YK.band 'Bonds break. Yet !{energy} comes out?' (96) at 0. Flame flares on cue 'energy'. Prereq chip 'Ionic and covalent bonds' on cue 'bonds' (after the first 2 s).","tts_text":"النار بتطلّع energy، مع إن الـ bonds لازم تتكسر الأول… إزاي؟","screen_text":"Bonds break. Yet energy comes out?"},{"id":"l2","visual":"Flame dims; CH4 + 2 O2 stretch (stretch 0→1) and come apart into separate YK.atomDisc atoms at the molecule's returned atom positions on cue 'بتتكسر'; atoms regroup into CO2 + 2 H2O (YK.molecule) on cue 'بتتكوّن'. Equation strip YK.formula 'CH_4 + 2O_2 -> CO_2 + 2H_2O' (mono 56, y 1450) on cue 'بتتكوّن' (the short's one equation). Prereq chip 'Writing and balancing chemical equations' on cue 'بتتكوّن'.","tts_text":"أي reaction: الـ bonds القديمة بتتكسر، و bonds جديدة بتتكوّن.","screen_text":"Old bonds break, new bonds form"},{"id":"l3","visual":"One bond close-up (two atomDisc r 90, y 1000): a coral arrow points INTO the bond as it snaps on cue 'بياخد'; tag 'energy in' (52, coral).","tts_text":"الـ bond breaking بياخد energy، لأن الـ atoms ماسكة في بعض.","screen_text":"Bond breaking: energy in"},{"id":"l4","visual":"Two atoms join; a mint arrow points OUT with a small flash on cue 'بيطلّع'; tag 'energy out' (52, mint).","tts_text":"والـ bond forming بيطلّع energy برة.","screen_text":"Bond forming: energy out"},{"id":"l5","visual":"Aha hold >= 1.5 s: YK.balance(ctx, 540, 1100, 700, {left:'energy in', right:'energy out', value: 0→0.6 (right side down)}) tips on cue 'أكتر'; the frame-0 flame returns small (y 1500) on cue 'زيادة'.","tts_text":"لو اللي طالع أكتر من اللي داخل، يبقى الـ reaction بيطلّع energy زيادة.","screen_text":"Out > in → the reaction gives out energy"},{"id":"l6","visual":"Myth (lesson's common mistake, G40): small coral arrow pointing OUT of a breaking bond on cue 'بيطلّع' + YK.wrongMark on cue 'لأ', gone 0.4 s later; the correct inward arrow returns bigger + ONE YK.rightMark on cue 'بياخد'.","tts_text":"ناس فاكرة إن الـ breaking بيطلّع energy… لأ، بياخد.","screen_text":"Breaking releases energy? ✕  It takes energy in ✓"},{"id":"l7","style":"curious","visual":"New-case check (made-up values; lesson used 500 in / 300 out). Balance at 50% alpha, beam level and inert (no tilt claims): 'in: 400 kJ' (mono 52) on the left pan on cue 'أربعمية'; 'out: 700 kJ' on the right on cue 'سبعمية'; a grey '?' over the pivot. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no tilt before YK.cue('l8').","tts_text":"الكسر خد أربعمية، والتكوين طلّع سبعمية… الـ reaction بيدي ولا بياخد؟","screen_text":"In: 400 kJ · Out: 700 kJ. Gives out or takes in?","pause_after_s":2},{"id":"l8","visual":"Answer: beam tips to 'out' + tag 'gives out 300 kJ' (mono 52) on cue 'تلتمية' + ONE YK.rightMark on cue 'بيدي'.","tts_text":"بيدي، تلتمية زيادة طالعة.","screen_text":"Gives out 300 kJ ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Bond breaking and bond forming', line:'Breaking: energy in · Forming: energy out', t, pulse:[{word:'in', at:YK.cue('l9','بياخد')}, {word:'out', at:YK.cue('l9','بيطلّعها')}]}) from line start (if the tts fix lands, cue on 'breaking' / 'forming'), held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 flame.","tts_text":"الـ breaking بياخد energy، والـ forming بيطلّعها.","screen_text":"Breaking: energy in · Forming: energy out","pause_after_s":1.5}],"logline":"A flame gives out energy although bonds must break first: in a reaction the reactants' bonds break (energy taken in) and new bonds form (energy given out); when more comes out than goes in, the reaction gives out energy.","concept_ids":["chem.bond-breaking-energy"]},"layer":null,"layer_fallback":false,"images":{"cover_9x16":"https://cdn.yaani.ai/files/648208217d6da90ceb4339731d0e82be350b59d61f2ab8dfe039de710d317c44.jpg","hero_21x9":"https://cdn.yaani.ai/files/fb014bb037cadb7dbcf6c80660cc86cf299302c8e9002190eed027ff05c5dae1.jpg","hero_4x5":"https://cdn.yaani.ai/files/0582b078265eafce323d124952c4742a99972a3a301a3c08a4a6f92f72721369.jpg","og":"https://cdn.yaani.ai/files/74fcec77547ae6ff2f9e1f94a2869e06736d29485bb6747ba0fa75ddc44df112.jpg","poster":"https://cdn.yaani.ai/files/50cf61445397346d4a8b4923cb047d3b680cfd806b52e99e30a722c693fc5e43.jpg","thumbnail":"https://cdn.yaani.ai/files/9dbf5926b9b53ad9c629abae9940cdd146040c86753b2a534f2b5192541856cb.jpg"},"thumbnail_variant":"a","files":[{"role":"captions","key":"ar-EG","url":"https://cdn.yaani.ai/files/850e13906741b3556c951e12bc00690c11544544291a1a26bb63f66c9cc698ed.vtt","mime":"text/vtt","size":1031},{"role":"cover_9x16","key":"","url":"https://cdn.yaani.ai/files/648208217d6da90ceb4339731d0e82be350b59d61f2ab8dfe039de710d317c44.jpg","mime":"image/jpeg","size":80992},{"role":"cover_9x16","key":"a/1080x1920.avif","url":"https://cdn.yaani.ai/files/43053d545d681f1b420a6908f3c4a88442621755f6b4d21bc892ef068b0bde46.avif","mime":"image/avif","size":8729},{"role":"cover_9x16","key":"a/1080x1920.jpg","url":"https://cdn.yaani.ai/files/648208217d6da90ceb4339731d0e82be350b59d61f2ab8dfe039de710d317c44.jpg","mime":"image/jpeg","size":80992},{"role":"cover_9x16","key":"a/1080x1920.png","url":"https://cdn.yaani.ai/files/279f7e770bf8cdcaa60bd124f978e3688f2abb364ca2a32673bb8ff59fdd35aa.png","mime":"image/png","size":132124},{"role":"cover_9x16","key":"a/1080x1920.webp","url":"https://cdn.yaani.ai/files/7f6a9b205548a867b00ebdd0f7fcfbc026fe2180a94132a897ab2444e939ae04.webp","mime":"image/webp","size":18040},{"role":"cover_9x16","key":"a/540x960.avif","url":"https://cdn.yaani.ai/files/fdfd95fbdc95c031515f38c06d38ddf462af40026335d7d40872dff999842a10.avif","mime":"image/avif","size":4922},{"role":"cover_9x16","key":"a/540x960.jpg","url":"https://cdn.yaani.ai/files/8cad38021cd2b94861ace754fd6dfd194cba2d43776327840c8293b99e530985.jpg","mime":"image/jpeg","size":36503},{"role":"cover_9x16","key":"a/540x960.webp","url":"https://cdn.yaani.ai/files/bad6a52d20a8c61c79215ecbed96355fad21cfd08afc6f5ae74a91d72e004db2.webp","mime":"image/webp","size":9030},{"role":"cover_9x16","key":"b/1080x1920.avif","url":"https://cdn.yaani.ai/files/5861ac568a27ff23cb6bb89f010504212bd843bf62c95dcd120e159cdd44f582.avif","mime":"image/avif","size":11328},{"role":"cover_9x16","key":"b/1080x1920.jpg","url":"https://cdn.yaani.ai/files/d9d62e74d91e1b9d9c4518fadd411a5f2730777149ef0820c68470b4f92e8086.jpg","mime":"image/jpeg","size":88814},{"role":"cover_9x16","key":"b/1080x1920.png","url":"https://cdn.yaani.ai/files/98cc11bcf62b3d65a215f72e0e656cbdc5ad48ea54ffc263776c27b52a5c26b5.png","mime":"image/png","size":96259},{"role":"cover_9x16","key":"b/1080x1920.webp","url":"https://cdn.yaani.ai/files/39cb8bcb36e908885a013f6d96d120328a8f3386e5981d1a4911b86640e1ae0b.webp","mime":"image/webp","size":20592},{"role":"cover_9x16","key":"b/540x960.avif","url":"https://cdn.yaani.ai/files/70fea50b196eafa99a3870c1e5c72fa348ef622a67567fd7bfada48228208aee.avif","mime":"image/avif","size":5529},{"role":"cover_9x16","key":"b/540x960.jpg","url":"https://cdn.yaani.ai/files/9010aa20c9a6b8e72711389a0d23b47b57c1dd586c6a3d8b053eb11b49d53c27.jpg","mime":"image/jpeg","size":40103},{"role":"cover_9x16","key":"b/540x960.webp","url":"https://cdn.yaani.ai/files/f07307ea4d9d8ad01299e5ac48ad4043eb76c5b577af0f02da5669fe7b8c2339.webp","mime":"image/webp","size":10142},{"role":"hero_21x9","key":"","url":"https://cdn.yaani.ai/files/fb014bb037cadb7dbcf6c80660cc86cf299302c8e9002190eed027ff05c5dae1.jpg","mime":"image/jpeg","size":88486},{"role":"hero_21x9","key":"a/1680x720.avif","url":"https://cdn.yaani.ai/files/c1183515234bc5f0d372e71e87fa99e13c0bd61abb18deebe28565812ed78cf2.avif","mime":"image/avif","size":6668},{"role":"hero_21x9","key":"a/1680x720.jpg","url":"https://cdn.yaani.ai/files/e460d8802d7f547cdb9c3a424fed6dc6452a2cc238aec906d1ab44eaf8d296f2.jpg","mime":"image/jpeg","size":53280},{"role":"hero_21x9","key":"a/1680x720.webp","url":"https://cdn.yaani.ai/files/1bb812639c483b4963854e226e3bbc419afaf7e64db5804e48f1ab35f8bcaefb.webp","mime":"image/webp","size":12146},{"role":"hero_21x9","key":"a/2520x1080.avif","url":"https://cdn.yaani.ai/files/f24c91c743a8ef542f2de1635bf1ee8be8facec5ba76e038f3e2eb38ed1d5a03.avif","mime":"image/avif","size":9967},{"role":"hero_21x9","key":"a/2520x1080.jpg","url":"https://cdn.yaani.ai/files/fb014bb037cadb7dbcf6c80660cc86cf299302c8e9002190eed027ff05c5dae1.jpg","mime":"image/jpeg","size":88486},{"role":"hero_21x9","key":"a/2520x1080.png","url":"https://cdn.yaani.ai/files/8a5940813406a827cf558e067e0131f4725692ce359df2bcb6d6c3fd0a998cce.png","mime":"image/png","size":138396},{"role":"hero_21x9","key":"a/2520x1080.webp","url":"https:/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بتطلّع energy مع إن الـ bonds لازم\nتتكسر الأول إزاي\nأي reaction الـ bonds القديمة بتتكسر و\nbonds جديدة بتتكوّن\nالـ bond breaking بياخد energy لأن الـ\natoms ماسكة في بعض\nوالـ bond forming بيطلّع energy برة\nلو اللي طالع أكتر من اللي داخل يبقى الـ\nreaction بيطلّع energy زيادة\nناس فاكرة إن الـ breaking بيطلّع energy لأ\nبياخد\nالكسر خد أربعمية والتكوين طلّع سبعمية الـ\nreaction بيدي ولا بياخد\nبيدي تلتمية زيادة طالعة\nالـ breaking بياخد energy والـ forming\nبيطلّعها","countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":7},{"id":"chem-s3-en.video-short-kin.activation-energy","kind":"short","version":1,"ord":297,"content_lang":"ar-EG","primary_concept_id":"kin.activation-energy","concepts":[{"concept_id":"kin.activation-energy","role":"primary"}],"title":"Activation energy and energy profile","payload":{"title":"Activation energy and energy profile","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pass v2, all lines: page.html must add <script> tags for lib/short.js and lib/beats.js (template.html lacks them: YK.band, YK.thinkRing, YK.cueLabel, YK.pill, YK.choice); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; look at stills before render.] Frame 0 complete: a gas burner (y 1400) with YK.molecule CH4 (r 36) drifting up, no flame, a small spark gap pulsing grey; YK.band 'No spark, no !{flame}. Why?' (104) at 0. Molecules jiggle on cue 'بيولع'; spark + flame burst on cue 'شرارة'.","tts_text":"البوتاجاز مش بيولع لوحده، لازم شرارة… ليه؟","screen_text":"No spark, no flame. Why?"},{"id":"l2","visual":"Two pairs of molecules: a slow pair bounces apart unchanged on cue 'تخبط'; a fast pair (speed lines) breaks and reacts on cue 'كفاية'. Prereq chip 'Bond breaking and bond forming' at line start.","tts_text":"الـ molecules لازم تخبط في بعض وهي معاها energy كفاية.","screen_text":"Molecules must collide with enough energy"},{"id":"l3","visual":"A vertical energy scale at x 200 (y 640–1500); 12 molecules (YK.dot) placed at seeded energies; a horizontal gold 'minimum' line across; only the dots above it light up on cue 'أقل'; label 'Activation energy' (64) on cue 'activation'. New term 1.","tts_text":"أقل energy الـ molecule محتاجاها عشان تتفاعل، دي الـ activation energy بتاعتها.","screen_text":"Activation energy: minimum energy to react"},{"id":"l4","visual":"YK.energyProfile(ctx, 108, 640, 864, 860, {reactants:20, products:-30, peak:80, draw: YK.prog(t, cue 'profile', +2), showEa:false, showDH:false, labels:{reactants:'Reactants', products:'Products', x:'Progress of reaction', y:'Potential energy'}}) (axis titles = book fig 1-3); title 'Energy profile' (56) on cue 'profile'; a ball rides the curve on cue 'ماشيين'. New term 2.","tts_text":"ده الـ energy profile: الـ energy وإحنا ماشيين في الـ reaction كده.","screen_text":"Energy profile"},{"id":"l5","visual":"Custom pink (#FF7AB6, the kit Ea colour) arrow from py(20) up to py(80) at the reactant side, drawn on cue 'الطلعة' + label 'Activation energy' (48); the Reactants level glows on cue 'reactants'.","tts_text":"الـ activation energy هي الطلعة من الـ reactants لفوق التل.","screen_text":"Activation energy: reactants up to the top"},{"id":"l6","visual":"Myth (top misconception, R11): a small coral arrow labelled 'energy given out?' (44) over the drop on cue 'بتطلع' + small YK.wrongMark on cue 'لأ', gone 0.4 s later; then the mint drop arrow (reactants → products level) + label 'energy given out' (48) on cue 'النزلة', smaller than the Ea arrow, which stays.","tts_text":"ناس فاكراها الـ energy اللي بتطلع… لأ، دي النزلة اللي بعدها.","screen_text":"Energy given out? ✕  That's the drop ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson used arrows X/Y/Z). Two small energyProfiles stacked top→bottom (108, 620, 864, 380) and (108, 1060, 864, 380), labels x/y/reactants/products false, showDH:false: hump 50 on cue 'خمسين', hump 150 on cue 'وخمسين'; YK.formula 'E_a = 50' / 'E_a = 150' (mono 48) left of each. YK.thinkRing(ctx, t, 540, 1540, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no balls before YK.cue('l8').","tts_text":"لو الـ activation energy خمسين في reaction، ومية وخمسين في التاني… مين أسهل؟","screen_text":"Activation energy 50 or 150: which reacts more easily?","pause_after_s":2},{"id":"l8","visual":"Answer: on the 50 profile many balls roll over the hump on cue 'molecules', few on the 150 one; ONE YK.rightMark on cue 'خمسين'.","tts_text":"اللي خمسين: التل أوطى، و molecules أكتر بتعدّيه.","screen_text":"50: lower hump, more molecules get over ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Activation energy and energy profile', line:'Activation energy: the climb, not the drop', t, pulse:[{word:'climb', at:YK.cue('l9','الطلعة')}, {word:'drop', at:YK.cue('l9','النزلة')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ activation energy هي الطلعة، مش النزلة.","screen_text":"Activation energy: the climb, not the drop","pause_after_s":1.5}],"logline":"Gas needs a spark to burn: molecules react only when they collide with at least the activation energy, the climb from the reactants to the top of the energy profile's hump; it is not the energy given out, which is the drop to the 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(96) at 0. Surface flashRect on cue 'catalysts'.","tts_text":"الـ transition elements بيعتبروا ideal catalysts… ليه هما بالذات؟","screen_text":"Why are they ideal catalysts?"},{"id":"l2","visual":"YK.energyProfile(ctx, 108, 640, 864, 760, {reactants:20, products:-30, peak:80, showDH:false, labels:{x:'Progress of reaction', y:'Potential energy', reactants:false, products:false}}) on line start; a second call with peak2:45 (gold catalysed curve, labels.catalysed 'with catalyst') cross-fades in on cue 'بيوطّي'; YK.pill 'faster' (48) on cue 'أسرع'. Prereq chips one at a time: 'Catalyst' at line start, then 'Activation energy and energy profile' on cue 'activation'. Book fig 1-3.","tts_text":"الـ catalyst بيوطّي الـ activation energy، فالـ reaction يمشي أسرع.","screen_text":"Catalyst: lower activation energy, faster"},{"id":"l3","visual":"Profile exits; zoom onto the surface (cols 4, r ≈ 108): small gold electron dots on the surface atoms with YK.label '4s' on cue 'four' and '3d' on cue 'three' (48). Prereq chip 'Electronic configuration of the first transition series' at line start. Book p.15.","tts_text":"السر في الـ four s والـ three d بتوعهم.","screen_text":"The reason: 4s and 3d"},{"id":"l4","visual":"Catalyst surface is Fe throughout (book p.15: iron ↔ Haber-Bosch N2 + H2 → NH3; never Ni with ammonia). N2 and H2 approach and adsorb (molecules p 0→1) on cue 'bonds': the kit draws the surface bonds as cyan dashed lines (not gold); surface atoms flash on cue 'surface'.","tts_text":"بتعمل bonds بين الـ surface atoms والـ molecules اللي بتتفاعل.","screen_text":"Bonds: surface atoms ↔ reacting molecules"},{"id":"l5","visual":"More molecules land and crowd the surface (cols 8 again, 6 molecules) on cue 'بتتلم'; label 'concentration ↑' (52) on cue 'concentration'. No YK.counter (it is a tween, not a count). New term (concentration).","tts_text":"فالـ molecules بتتلم على الـ surface، والـ concentration بتاعتها تزيد.","screen_text":"Concentration on the surface increases"},{"id":"l6","visual":"Adsorbed molecules stretch (stretch 0→1: bonds dashed) on cue 'بتضعف'; a mini energyProfile (560, 600, 412, 320, labels all false) whose hump drops (peak 80 → 45) on cue 'تقل'.","tts_text":"والـ bonds اللي جواها بتضعف، فالـ activation energy تقل.","screen_text":"Reactant bonds weaken → activation energy decreases"},{"id":"l7","visual":"Myth (concept misconception 1, G40): products leave the surface (leave 0→1); small coral ghost of a shrinking surface on cue 'بيخلص' + YK.wrongMark, gone 0.4 s later; the full surface glows mint + ONE YK.rightMark on cue 'بيفضل'. Products leaving are NH3 (Fe surface).","tts_text":"الـ catalyst مش بيخلص، بيفضل زي ما هو.","screen_text":"Used up? ✕  Left unchanged ✓"},{"id":"l8","style":"curious","visual":"New-case check (concept misconception 2; lesson used a made-up 180/60/100 kJ profile). Two YK.choice chips 'more product?' / 'same, faster?' (y 1000 / 1180) on cues 'أكتر' / 'أسرع'. No flasks or counters. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l8'), end: YK.cue('l9')}) through the stitched silence (pause_after_s 2.0); no answer before YK.cue('l9').","tts_text":"حطينا catalyst… هنطلع products أكتر، ولا نفس الكمية أسرع؟","screen_text":"Catalyst: more product, or same product faster?","pause_after_s":2},{"id":"l9","visual":"Answer: the l2 profile returns: reactant and product levels flash as unchanged, only the hump drops on cue 'التل'; 'same, faster?' choice glows mint + ONE YK.rightMark on cue 'الكمية'.","tts_text":"نفس الكمية أسرع: التل بس هو اللي بيوطى.","screen_text":"Same amount, faster ✓"},{"id":"l10","visual":"Voiced lock-in: YK.takeaway({title:'Catalytic activity of transition elements', line:'With 4s and 3d: a lower hump', t, pulse:[{word:'4s', at:YK.cue('l10','four')}, {word:'3d', at:YK.cue('l10','three')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"بالـ four s والـ three d، التل بيوطى.","screen_text":"With 4s and 3d: a lower hump","pause_after_s":1.5}],"logline":"Transition elements are ideal catalysts because their 4s and 3d electrons form bonds between surface atoms and reacting molecules: the molecules' concentration on the surface rises, their bonds weaken, the activation energy falls and the reaction speeds up, while the catalyst is left unchanged and the product is the same (book p.15, fig 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!{reactant}?' (104) at 0. Arrow glows on cue 'السهم'. Prereq chip 'Writing and balancing chemical equations' on cue 'reactant' (after the first 2 s).","tts_text":"حاجة مكتوبة فوق السهم… دي reactant ولا لأ؟","screen_text":"Over the arrow: a reactant?"},{"id":"l2","visual":"State symbols pop into the equation (2H_2O_2(l) … 2H_2O(l) + O_2(g), formula.js syntax; fit 864 px, >= 56 px, check stills) and glow on cue 'state' + label 'State symbols' (56); a 2×2 grid of cards (y 1100 / 1380): '(s) solid', '(l) liquid', '(g) gas' with tiny particle icons drop in on cues 'solid', 'liquid', 'gas'. Prereq chip 'States of matter, melting and boiling points' at line start. New term 1.","tts_text":"الـ state symbols بتقولك: solid، liquid، ولا gas جوه القوسين.","screen_text":"State symbols: (s) (l) (g)"},{"id":"l3","visual":"The 4th card '(aq) aqueous' with a small beaker and dissolving particles on cue 'aqueous'; label 'dissolved in water' (48) on cue 'دايب'. New term 2.","tts_text":"و aqueous يعني دايب في المية.","screen_text":"(aq) aqueous: dissolved in water"},{"id":"l4","visual":"Cards exit; a big empty arrow (y 1100) gets three tags stacked above it: 'temperature', 'pressure', 'catalyst' (48 each) on their cues; title 'Conditions' (56) on cue 'conditions'. New term 3.","tts_text":"فوق السهم بنكتب الـ conditions، زي الـ temperature والـ pressure والـ catalyst كمان.","screen_text":"Over the arrow: conditions"},{"id":"l5","visual":"Back to the fig 1-3 equation: 'MnO_2' stays above the arrow, a coral ghost copy tries to slide into the reactants and bounces back on cue 'reactant'; a small MnO2 powder pile stays the same size on cue 'بيخلص'. Prereq chip 'Catalyst' at line start.","tts_text":"الـ catalyst اللي فوق السهم مش reactant، وهو نفسه مش بيخلص.","screen_text":"MnO₂: a catalyst, not a reactant"},{"id":"l6","style":"curious","visual":"New-case check (lesson used C + H₂O(v) at 1000 °C). A bare arrow (y 1000) with 'Fe' on cue 'iron' and '200 atm' on cue 'atmosphere' above it (mono 56); reactant/product sides blank. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l6'), end: YK.cue('l7')}) through the stitched silence (pause_after_s 2.0); no tags before YK.cue('l7').","tts_text":"ولو فوق السهم iron وميتين atmosphere… دول بيتفاعلوا؟","screen_text":"Over the arrow: Fe, 200 atm. Reactants?","pause_after_s":2},{"id":"l7","visual":"Answer: tag 'catalyst' under 'Fe' on cue 'catalyst'; 'pressure' under '200 atm' on cue 'pressure'; ONE YK.rightMark on cue 'conditions'.","tts_text":"لأ، دول conditions: الـ iron catalyst، والميتين دول pressure عالي.","screen_text":"No: Fe = catalyst, 200 atm = pressure ✓"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'Reading equations: states and conditions', line:'Over the arrow: conditions, not reactants', t, pulse:[{word:'conditions', at:YK.cue('l8','conditions')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"فوق السهم conditions، مش reactants خالص.","screen_text":"Over the arrow: conditions, not reactants","pause_after_s":1.5}],"logline":"An equation tells more than formulas: state symbols (s), (l), (g), (aq) give each substance's state, and what is written over the arrow (temperature, pressure, catalyst) is a condition, not a 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مكتوبة فوق السهم دي reactant ولا لأ\nالـ state symbols بتقولك solid liquid ولا\ngas جوه القوسين\nو aqueous يعني دايب في المية\nفوق السهم بنكتب الـ conditions زي الـ\ntemperature والـ pressure والـ catalyst\nكمان\nالـ catalyst اللي فوق السهم مش reactant\nوهو نفسه مش بيخلص\nولو فوق السهم iron وميتين atmosphere دول\nبيتفاعلوا\nلأ دول conditions الـ iron catalyst\nوالميتين دول pressure عالي\nفوق السهم conditions مش reactants خالص","countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":10},{"id":"chem-s3-en.video-short-chem.ammonia-haber","kind":"short","version":1,"ord":303,"content_lang":"ar-EG","primary_concept_id":"chem.ammonia-haber","concepts":[{"concept_id":"chem.ammonia-haber","role":"primary"}],"title":"Haber-Bosch method for ammonia","payload":{"title":"Haber-Bosch method for ammonia","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pass v2, all lines: page.html must add <script> tags for lib/short.js and lib/beats.js (template.html lacks them: YK.band, YK.thinkRing, YK.cueLabel, YK.pill, YK.choice); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; look at stills before render.] Frame 0 complete: a stream of YK.molecule N2 (r 34) drifting from a pale sky band into YK.icon 'factory' (200, y 1150) and YK.molecule NH3 floating out the other side, looping from t=0; YK.band '!{Ammonia} from the air?' (104) at 0. N2 glows on cue 'nitrogen', NH3 on cue 'ammonia'. (Air mostly N₂: general fact, not in the book; keep it voice-only, no number on screen.)","tts_text":"الهوا معظمه nitrogen… والمصانع بتعمل منه ammonia. إزاي؟","screen_text":"Ammonia from the air?"},{"id":"l2","visual":"Title 'Haber-Bosch method' (64) on cue 'Haber-Bosch'; N2 and H2 molecules meet and an NH3 forms on cue 'بيدّوا'. Prereq chip 'Reading equations: states and conditions' at line start. New term 1.","tts_text":"في طريقة Haber-Bosch، الـ nitrogen والـ hydrogen بيدّوا الـ ammonia بتاعتنا.","screen_text":"Haber-Bosch method: nitrogen + hydrogen → ammonia"},{"id":"l3","visual":"YK.formula 'N_2(g) + 3H_2(g) -> 2NH_3(g)' (mono 60, y 800) builds term by term on cues 'nitrogen', 'تلاتة', 'اتنين'; under it 1 N2 + 3 H2 regroup into 2 NH3 (YK.molecule r 36) on cue 'بيدّوا' (atoms conserved).","tts_text":"كل nitrogen مع تلاتة hydrogen بيدّوا اتنين ammonia في الآخر.","screen_text":"N₂(g) + 3H₂(g) → 2NH₃(g)"},{"id":"l4","visual":"The arrow gets its book conditions, all OVER the arrow as in the book (p.15): '->[500 °C / 200 atm, Fe]' — '500 °C' on cue 'خمسمية', '200 atm' on cue 'atmosphere', 'Fe' on cue 'iron'. Fit 864 px (formula >= 56 px, conditions >= 40 px); check stills.","tts_text":"وفوق السهم: خمسمية درجة، وميتين atmosphere، والـ iron catalyst هنا.","screen_text":"500 °C / 200 atm, Fe"},{"id":"l5","visual":"Equation moves up (y 600, 48 px as a reference strip); one YK.molecule N2 close-up (r 110, y 1050, triple bond) shakes but does not break on cue 'قوي'; a dashed progress bar crawling slowly + label 'slow' (52) on cue 'بطيء' (no clock/snail icon in the kit). Approved lesson fact.","tts_text":"الـ bond في الـ nitrogen قوي، فالـ reaction بطيء.","screen_text":"N₂: a very strong bond → slow"},{"id":"l6","visual":"Small YK.energyProfile(ctx, 108, 1060, 864, 420, {reactants:20, products:-20, peak:85, labels:{x:false, y:false, reactants:false, products:false}, showDH:false}); a second call with peak2:45 (gold) fades in on cue 'بيوطّي'; NH3 molecules pop out faster on cue 'أسرع'. Prereq chip 'Catalyst' on cue 'iron'.","tts_text":"والـ iron بيوطّي الـ activation energy، فالـ ammonia تتكوّن أسرع.","screen_text":"Fe lowers the activation energy → faster"},{"id":"l7","visual":"Myth (lesson's common mistake; the concept records none): small coral ghost 'Fe' sliding into the reactant side on cue 'reactant' + small YK.wrongMark, gone 0.4 s later; 'Fe' stays over the arrow; the '2NH_3' product glows unchanged on cue 'ammonia'.","tts_text":"الـ iron مش reactant، ومش بيزوّد الـ ammonia خالص.","screen_text":"Fe a reactant? ✕  Fe adds no ammonia"},{"id":"l8","style":"curious","visual":"New-case check (lesson used 6 H₂ → 4 NH₃). Three N2 molecules (+ greyed H2) at y 1000 on cue 'تلاتة'; YK.band '3 N_2 → ? NH_3' (80) on cue 'ammonia'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l8'), end: YK.cue('l9')}) through the stitched silence (pause_after_s 2.0); no NH3 before YK.cue('l9').","tts_text":"لو عندنا تلاتة nitrogen، هيطلع كام ammonia في الآخر؟","screen_text":"3 N₂ react fully. How many NH₃?","pause_after_s":2},{"id":"l9","visual":"Answer: six NH3 molecules pop out, two from each N2, on cue 'ستة'; label '6 NH_3' (mono 64) + ONE YK.rightMark.","tts_text":"ستة، كل nitrogen واحد بيدّي اتنين.","screen_text":"6 NH₃ ✓ (1 N₂ → 2 NH₃)"},{"id":"l10","visual":"Voiced lock-in: YK.takeaway({title:'Haber-Bosch method for ammonia', line:'Ammonia by Haber-Bosch, iron catalyst', formula:'N_2 + 3H_2 ->[500 °C / 200 atm, Fe] 2NH_3', t, pulse:[{word:'Haber-Bosch', at:YK.cue('l10','Haber-Bosch')}, {word:'iron', at:YK.cue('l10','iron')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 factory stream.","tts_text":"الـ ammonia بطريقة Haber-Bosch، والـ iron catalyst فيها.","screen_text":"Ammonia by Haber-Bosch, iron catalyst","pause_after_s":1.5}],"logline":"Ammonia is made from nitrogen and hydrogen by the Haber-Bosch method, N₂(g) + 3H₂(g) → 2NH₃(g) at 500 °C and 200 atm with iron as the catalyst (book p.15); nitrogen's strong bond makes the reaction slow, and iron lowers the activation energy without being a reactant.","concept_ids":["chem.ammonia-haber"]},"layer":null,"layer_fallback":false,"images":{"cover_9x16":"https://cdn.yaani.ai/files/9a819fc0244bd154cd9ac5a1a79d88c7059aac96fa6394198ee149ec2b0686ca.jpg","hero_21x9":"https://cdn.yaani.ai/files/3c75457c592188e34d80bd8303a760e8af2b713c3ab341ba033d39cc76815155.jpg","hero_4x5":"https://cdn.yaani.ai/files/c56948d41d86c85c6d0895bef94536a703b3581b2229860398845ea6f75a7195.jpg","og":"https://cdn.yaani.ai/files/3c34b26263a6d3d721023e5e2fecad273b4fa921e9780fa57b7f95aa34ef2a06.jpg","poster":"https://cdn.yaani.ai/files/0b192ac4ac72d0b19ca0c6b1f64431299e9f466fb0f795e707cdef80da45a962.jpg","thumbnail":"https://cdn.yaani.ai/files/2c2556490aba8aaf28a0bca65a473b8bc4efcf4939cf79ce9705cf57c56c0b0f.jpg"},"thumbnail_variant":"a","files":[{"role":"captions","key":"ar-EG","url":"https://cdn.yaani.ai/files/b40ecad7fee62d41dbd255c3d56cd9663ccb1154084d3029e9a706a719683775.vtt","mime":"text/vtt","size":1140},{"role":"cover_9x16","key":"","url":"https://cdn.yaani.ai/files/9a819fc0244bd154cd9ac5a1a79d88c7059aac96fa6394198ee149ec2b0686ca.jpg","mime":"image/jpeg","size":111041},{"role":"cover_9x16","key":"a/1080x1920.avif","url":"https://cdn.yaani.ai/files/cd7573885b6770f64f7c804b5b66841b42c9680858a48f63db1f4a9d16606b00.avif","mime":"image/avif","size":14370},{"role":"cover_9x16","key":"a/1080x1920.jpg","url":"https://cdn.yaani.ai/files/9a819fc0244bd154cd9ac5a1a79d88c7059aac96fa6394198ee149ec2b0686ca.jpg","mime":"image/jpeg","size":111041},{"role":"cover_9x16","key":"a/1080x1920.png","url":"https://cdn.yaani.ai/files/9cb73d8717f657a533f8e67bf04bca641718c6a672cdd81f6393c74681af5965.png","mime":"image/png","size":132756},{"role":"cover_9x16","key":"a/1080x1920.webp","url":"https://cdn.yaani.ai/files/e0866f1936f6cc9fa983befba5d28dd83d351fc2fa2041d3c6754ce12239b57a.webp","mime":"image/webp","size":25956},{"role":"cover_9x16","key":"a/540x960.avif","url":"https://cdn.yaani.ai/files/34679ccc1cb04e168182ff6b96992721df1da66085b71150554732f3ad4018de.avif","mime":"image/avif","size":7524},{"role":"cover_9x16","key":"a/540x960.jpg","url":"https://cdn.yaani.ai/files/300db36756d9c3cb0126b5297246b727817eb40b062970d59fcf1fed2375a6ab.jpg","mime":"image/jpeg","size":48382},{"role":"cover_9x16","key":"a/540x960.webp","url":"https://cdn.yaani.ai/files/791b1c473338234750411fe1ae72134768b3dc9e82e233346fc589290c195e74.webp","mime":"image/webp","size":12944},{"role":"cover_9x16","key":"b/1080x1920.avif","url":"https://cdn.yaani.ai/files/d7de65b7741008321b3d88851fab922a25a513f1e19ca4fb1cc719ea27b3829a.avif","mime":"image/avif","size":11490},{"role":"cover_9x16","key":"b/1080x1920.jpg","url":"https://cdn.yaani.ai/files/a239d7d628f8903378ec6ec9954e13df96a1f41a1a32d3662001364c7d0a0e22.jpg","mime":"image/jpeg","size":76897},{"role":"cover_9x16","key":"b/1080x1920.png","url":"https://cdn.yaani.ai/files/94e838efa18130f5e392cc012b7c28f45b17770987cc31ef7924f57bf6daddc1.png","mime":"image/png","size":109336},{"role":"cover_9x16","key":"b/1080x1920.webp","url":"https://cdn.yaani.ai/files/fc3a1aa2fe3d1ee841195b826fb9829cbea53d450b1f27747d3dec91c18e367b.webp","mime":"image/webp","size":17956},{"role":"cover_9x16","key":"b/540x960.avif","url":"https://cdn.yaani.ai/files/842eb7a1c8810f884fac3cf71e60ee04145dc028fd8fe5bae8858fcc77beec1c.avif","mime":"image/avif","size":5364},{"role":"cover_9x16","key":"b/540x960.jpg","url":"https://cdn.yaani.ai/files/f18f5a58a9903c71a5ac02f8cab7c94af88155ef5d7e5f7dafa3f89057ea630c.jpg","mime":"image/jpeg","size":33082},{"role":"cover_9x16","key":"b/540x960.webp","url":"https://cdn.yaani.ai/files/c76e04f0905fd9ce8c4b4f752a8efed83199bace0906742ef3004bf278f52bcf.webp","mime":"image/webp","size":8456},{"role":"hero_21x9","key":"","url":"https://cdn.yaani.ai/files/3c75457c592188e34d80bd8303a760e8af2b713c3ab341ba033d39cc76815155.jpg","mime":"image/jpeg","size":96010},{"role":"hero_21x9","key":"a/1680x720.avif","url":"https://cdn.yaani.ai/files/f219bfc5918c40f88df6be7a5db45a969a3738d2c538c5dc193766021bcce018.avif","mime":"image/avif","size":8326},{"role":"hero_21x9","key":"a/1680x720.jpg","url":"https://cdn.yaani.ai/files/d00d96002d8bbd5090c48ca5ffbf4d03b494c14c6cfa7c9b0db163e155c3080c.jpg","mime":"image/jpeg","size":56957},{"role":"hero_21x9","key":"a/1680x720.webp","url":"https://cdn.yaani.ai/files/60197611ea706eef0b772044fc39e9ad1625e9e58153bf8d971478c8470327d9.webp","mime":"image/webp","size":14124},{"role":"hero_21x9","key":"a/2520x1080.avif","url":"https://cdn.yaani.ai/files/754b65e1a4b5376b6217a6430e1943e1e8e3d8faceefc6c0a51cbc228bf167fa.avif","mime":"image/avif","size":11977},{"role":"hero_21x9","key":"a/2520x1080.jpg","url":"https://cdn.yaani.ai/files/3c75457c592188e34d80bd8303a760e8af2b713c3ab341ba033d39cc76815155.jpg","mime":"image/jpeg","size":96010},{"role":"hero_21x9","key":"a/2520x1080.png","url":"https://cdn.yaani.ai/files/40429ce563de6249c4f88fa3312a1a5585cc37abe10c96bcfa1cc56cfa10061a.png","mime":"image/png","size":138744},{"role":"hero_21x9","key":"a/2520x1080.webp","url":"https:/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(104) at 0. Disc pulses on cue 'catalyst'. Prereq chip 'Catalytic activity of transition elements' on cue 'المصانع' (after the first 2 s).","tts_text":"ينفع catalyst واحد يشتغل في كل المصانع؟","screen_text":"One catalyst for all factories?"},{"id":"l2","visual":"Top factory row: fine nickel powder (many small YK.atomDisc 'Ni' grains, r 14, symbol:false + one labelled 'Ni' r 44) on cue 'nickel'; tag 'finely divided' (44) on cue 'finely'; an oil drop + H2 molecules (r 22) turn into a solid fat block on cue 'hydrogenation' (approved lesson: liquid oils → solid fats); name 'Hydrogenation of oils' (48) in the slot. New term 1. Book p.14.","tts_text":"الـ nickel وهو finely divided بيشتغل في hydrogenation الزيوت.","screen_text":"Finely divided Ni: hydrogenation of oils"},{"id":"l3","visual":"Middle row: an 'Fe' YK.atomDisc (r 44); NH3 molecules out on cue 'ammonia'; name 'Haber-Bosch' (48) on cue 'Haber-Bosch'. Prereq chip 'Haber-Bosch method for ammonia' at line start.","tts_text":"والـ iron في طريقة Haber-Bosch، بيعمل الـ ammonia بسرعة.","screen_text":"Fe: Haber-Bosch (ammonia)"},{"id":"l4","visual":"Bottom row: 'V_2O_5' tag (mono 52) on cue 'vanadium'; name 'Contact method' (48) on cue 'contact'; a small flask (YK.icon 'flask') labelled 'H_2SO_4' fills on cue 'sulphuric'. New term 2. Book p.15 (book spelling 'sulphuric').","tts_text":"والـ vanadium pentoxide في الـ contact method، ومنها بيطلع الـ sulphuric acid بعدين.","screen_text":"V₂O₅: contact method → sulphuric acid"},{"id":"l5","visual":"Factories shrink up; YK.formula '2SO_2(g) + O_2(g) ->[V_2O_5 / 450 °C] 2SO_3(g)' (mono 56, y 1000; conditions over the arrow as in the book, p.15) builds; 'V_2O_5' drops onto the arrow on cue 'vanadium'; '450 °C' on cue 'والأربعمية'. The short's only equation. Prereq chip 'Reading equations: states and conditions' at line start.","tts_text":"وفي معادلتها، الـ vanadium pentoxide والأربعمية وخمسين درجة فوق السهم.","screen_text":"2SO₂ + O₂ → 2SO₃ (V₂O₅ / 450 °C)"},{"id":"l6","visual":"Myth (top misconception, R11: swapped pairs): a small coral 'Fe' tag slides onto the contact-method arrow on cue 'iron' + small YK.wrongMark on cue 'غلط', gone 0.4 s later; 'V_2O_5' returns to its place, bigger.","tts_text":"اللي بيبدّل وبيحط الـ iron في الـ contact method… غلط.","screen_text":"Fe for the contact method? ✕"},{"id":"l7","style":"curious","visual":"New-case check (a product never named in the lesson; made by hydrogenating oils, true and consistent with the approved lesson 'liquid oils → solid fats'). A custom tub (rounded rect + lid, no brand) labelled 'vegetable ghee' (48) on cue 'السمنة'; an oil drop + H2 molecules on cue 'hydrogen'; three YK.choice chips 'Ni' / 'Fe' / 'V_2O_5' (y 1250) on cue 'catalyst'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer before YK.cue('l8').","tts_text":"السمنة النباتي بتتعمل من زيت و hydrogen… الـ catalyst هنا إيه؟","screen_text":"Vegetable ghee: oil + hydrogen. Which catalyst?","pause_after_s":2},{"id":"l8","visual":"Answer: 'Ni' choice mint + ONE YK.rightMark on cue 'nickel'; powder grains sprinkle into the oil and it sets solid on cue 'hydrogenation'.","tts_text":"الـ nickel وهو finely divided، عشان ده hydrogenation زيوت.","screen_text":"Finely divided Ni: hydrogenation ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Nickel, iron and V₂O₅ as catalysts', line:'The process decides the catalyst', formula:'Ni: oils · Fe: NH_3 · V_2O_5: H_2SO_4', t, pulse:[{word:'process', at:YK.cue('l9','process')}, {word:'catalyst', at:YK.cue('l9','catalyst')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 factories.","tts_text":"الـ process بتحدد الـ catalyst بتاعها.","screen_text":"The process decides the catalyst","pause_after_s":1.5}],"logline":"Each industrial process has its own transition-element catalyst: finely divided nickel for the hydrogenation of oils, iron for the Haber-Bosch method (ammonia), vanadium pentoxide for the contact method (2SO₂ + O₂ → 2SO₃ at 450 °C, towards sulphuric acid) (book 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catalyst واحد يشتغل في كل المصانع\nالـ nickel وهو finely divided بيشتغل في\nhydrogenation الزيوت\nوالـ iron في طريقة Haber-Bosch بيعمل الـ\nammonia بسرعة\nوالـ vanadium pentoxide في الـ contact\nmethod ومنها بيطلع الـ sulphuric acid\nبعدين\nوفي معادلتها الـ vanadium pentoxide\nوالأربعمية وخمسين درجة فوق السهم\nاللي بيبدّل وبيحط الـ iron في الـ contact\nmethod غلط\nالسمنة النباتي بتتعمل من زيت و hydrogen\nالـ catalyst هنا إيه\nالـ nickel وهو finely divided عشان ده\nhydrogenation زيوت\nالـ process بتحدد الـ catalyst بتاعها","countable":true,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":12},{"id":"chem-s3-en.video-short-chem.elements-compounds-mixtures","kind":"short","version":1,"ord":336,"content_lang":"ar-EG","primary_concept_id":"chem.elements-compounds-mixtures","concepts":[{"concept_id":"chem.elements-compounds-mixtures","role":"primary"}],"title":"Elements, compounds and mixtures","payload":{"title":"Elements, compounds and mixtures","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); ≤ 1 written equation on screen at a time; YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; no furnace zones, slag or limestone (book pp.16-18 only); look at stills before render.] Frame 0 complete: two panels side by side (x 300 / 780, y 1050): LEFT a pile of grey iron filings + yellow sulphur grains (YK.swarm dots, seed 1) with a YK.magnet above lifting a grey tuft; RIGHT a black lump with the same magnet above and nothing lifting; YK.band 'Same iron. Why no !{pull}?' (104) at 0. Grey tuft jumps on cue 'شدّه'; right magnet shakes (no lift) on cue 'لأ'.","tts_text":"نفس الـ iron… الـ magnet شدّه مرة، ومرة لأ. ليه؟","screen_text":"Same iron. Why no pull?"},{"id":"l2","visual":"Right panel fades. Left pile centre (y 1000): grey Fe dots and yellow S dots stay apart (no links), labels 'Fe' and 'S' (52) on cues 'iron' / 'sulphur'; YK.pill 'Mixture' (56, cyan) on cue 'mixture'. Prereq chip 'Elements and their symbols' at line start (after 2 s). New term 1.","tts_text":"ده mixture: الـ iron والـ sulphur مخلوطين بس.","screen_text":"Mixture: Fe + S, just mixed"},{"id":"l3","visual":"The magnet sweeps over the pile on cue 'magnet': grey dots ride up to it, yellow dots stay; label 'physical means' (48) on cue 'physical'.","tts_text":"فبنفصلهم بطريقة physical، زي الـ magnet كده.","screen_text":"Separated by physical means: a magnet"},{"id":"l4","visual":"A fresh Fe + S pile on a small flame (YK.glowCircle under it) on cue 'سخّناهم'; dots pair Fe–S and bond (short white links) on cue 'اتحدوا'; the pile turns into one black lump labelled YK.label 'FeS' (mono 64) on cue 'sulphide'; YK.pill 'Compound' (56, gold) on cue 'compound'. New term 2.","tts_text":"بس لما سخّناهم، اتحدوا وعملوا compound جديد: iron two sulphide، لونه أسود.","screen_text":"Heated: FeS, a new compound"},{"id":"l5","visual":"Zoom into the black lump: a neat grid of Fe–S pairs; tag '1 Fe : 1 S' (52, mono) on cue 'لواحد'; a magnet above stays idle and label 'new properties' (48) on cue 'properties'.","tts_text":"الـ compound نسبته ثابتة، واحد iron لواحد sulphur، وليه properties جديدة.","screen_text":"Compound: fixed ratio, new properties"},{"id":"l6","visual":"Myth (concept misconception 1): Split screen: mixture pile (dots apart) left, FeS grid right; coral '=' pill between them. Small coral pill on cue 'mixture' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'خالص' and stays longer on screen. The '=' turns into '≠' (mint, 64) on cue 'خالص'.","tts_text":"ناس فاكرة إن الـ mixture والـ compound زي بعض… لأ خالص.","screen_text":"Mixture = compound? ✕"},{"id":"l7","style":"curious","visual":"New-case check (the lesson sorted water, salt water, Cu, air, CO2, iron + sand, an Fe2O3 rock; not MgO). A small white powder heap (y 1000) with YK.label 'MgO' (mono 72) on cue 'magnesium'; two YK.choice chips 'Compound' / 'Mixture' (y 1260) on cues 'compound' / 'mixture'; YK.band 'MgO: compound or mixture?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"بودرة بيضا اسمها magnesium oxide… ده compound ولا mixture يا ترى؟","screen_text":"MgO: compound or mixture?","pause_after_s":2},{"id":"l8","visual":"Answer: the heap zooms to Mg–O pairs in a grid (Mg atomDisc grey, O red) on cue 'متحدين'; 'Compound' chip glows mint, 'Mixture' dims on cue 'compound'; tag '1 Mg : 1 O' (52) on cue 'ثابتة'; ONE YK.rightMark.","tts_text":"ده compound، لأن الـ magnesium والـ oxygen متحدين بنسبة ثابتة.","screen_text":"Compound: Mg and O, fixed ratio ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Elements, compounds and mixtures', line:'Compound: combined. Mixture: just mixed', t, pulse:[{word:'combined', at:YK.cue('l9','متحد')}, {word:'mixed', at:YK.cue('l9','مخلوط')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ compound متحد، والـ mixture مخلوط بس.","screen_text":"Compound: combined. Mixture: just mixed","pause_after_s":1.5}],"logline":"Iron and sulphur just mixed keep their properties, so a magnet pulls the iron out; heated, they combine into black iron(II) sulphide, FeS, a compound with a fixed ratio and new properties that a magnet cannot 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الـ iron الـ magnet شدّه مرة ومرة لأ\nليه\nده mixture الـ iron والـ sulphur مخلوطين\nبس\nفبنفصلهم بطريقة physical زي الـ magnet كده\nبس لما سخّناهم اتحدوا وعملوا compound جديد\niron two sulphide لونه أسود\nالـ compound نسبته ثابتة واحد iron لواحد\nsulphur وليه properties جديدة\nناس فاكرة إن الـ mixture والـ compound زي\nبعض لأ خالص\nبودرة بيضا اسمها magnesium oxide ده\ncompound ولا mixture يا ترى\nده compound لأن الـ magnesium والـ oxygen\nمتحدين بنسبة ثابتة\nالـ compound متحد والـ mixture مخلوط بس","countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":8},{"id":"chem-s3-en.video-short-fe.occurrence","kind":"short","version":1,"ord":338,"content_lang":"ar-EG","primary_concept_id":"fe.occurrence","concepts":[{"concept_id":"fe.occurrence","role":"primary"}],"title":"Iron: abundance and suitability of iron ore","payload":{"title":"Iron: abundance and suitability of iron ore","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); ≤ 1 written equation on screen at a time; YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; no furnace zones, slag or limestone (book pp.16-18 only); look at stills before render.] Frame 0 complete: a big YK.elementCard 'Fe' (Z 26, config:'' so no configuration prints) centre (y 900) with YK.icon 'bridge', 'factory', 'rail' (160, steel) orbiting it in an arc; YK.band 'Most important = most !{abundant}?' (96) at 0, accentAt cue 'الأكتر'. Icons pulse on cue 'metal'.","tts_text":"الـ iron أهم metal… بس هو الأكتر؟","screen_text":"Most important metal = most abundant?"},{"id":"l2","visual":"Myth (concept misconception 1 (TOP)): four EQUAL rank tiles stacked top → bottom (x 160–920, y 820 / 960 / 1100 / 1240, 120 px tall, labelled '1st'–'4th' at the left; no bar heights: the book gives ranks only); a grey Fe tile jumps into the '1st' slot with a coral '1st?' pill. Small coral pill on cue 'واحد' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'الرابع' and stays longer on screen. The Fe tile slides down to the '4th' slot with a gold '4th' tag on cue 'الرابع'.","tts_text":"ناس فاكرة إنه رقم واحد… لأ، هو الرابع.","screen_text":"Most abundant? ✕  4th ✓"},{"id":"l3","visual":"The empty rank tiles fill top → bottom: YK.label 'O', 'Si', 'Al' (52) on cues 'oxygen', 'silicon', 'aluminum' (equal tiles, no other values); the Fe tile gets YK.label '5% by mass' (mono 52) on cue 'بخمسة'. Footnote 'Book p.16' (40, 60%).","tts_text":"بعد الـ oxygen والـ silicon والـ aluminum، بخمسة في المية.","screen_text":"After O, Si, Al · 5% by mass"},{"id":"l4","visual":"Chart exits; a meteorite streaks down from the top right (YK.rock steel-grey with a short glow trail) and lands centre on cue 'meteorites'; tag 'Pure iron 90%' (52) on cue 'تسعين'; YK.pill 'only here' (48) on cue 'بس'. New term 1.","tts_text":"الـ iron النقي، تسعين في المية، في الـ meteorites بس.","screen_text":"Pure iron (90%): only in meteorites"},{"id":"l5","visual":"Ground cross-section (y 1100-1600); three YK.ore rocks (hematite, magnetite, limonite; label:false) appear in the rock layer on cue 'ores'; inside one rock a zoom bubble shows red Fe2O3 grains labelled 'mostly iron oxides' (48) on cue 'oxides' (book: ores contain iron oxides; siderite, a carbonate, is the exception, so never 'ore = oxide') and grey specks 'impurities' (48) on cue 'impurities'. Prereq chip 'Elements, compounds and mixtures' at line start. New terms 2 (ore) and 3 (impurities, glossed by the picture).","tts_text":"في الأرض، ores فيها iron oxides غالبًا و impurities.","screen_text":"Ores: mostly iron oxides + impurities"},{"id":"l6","visual":"One hematite YK.ore (r 150, y 900, gauge reveal on cue 'نسبة', label:true) with a checklist card on the right (x 620): row '1) Iron %' ticks in on cue 'أولًا'; header 'Suitable?' (56) on cue 'suitable'.","tts_text":"إمتى الـ ore يبقى suitable؟ نسبة الـ iron فيه أولًا.","screen_text":"Suitable ore? 1) iron %"},{"id":"l7","visual":"Row '2) Composition of impurities' (book wording) enters on cue 'impurities'; row '3) Harmful elements' enters on cue 'harmful'; a small yellow 'S' dot (YK.atomDisc) with a coral glow sits in the ore on cue 'sulphur'. Book p.16: three factors.","tts_text":"تانيًا الـ impurities، وتالتًا الـ harmful elements زي الـ sulphur مثلًا.","screen_text":"2) Composition of impurities  3) Harmful elements (e.g. S)"},{"id":"l8","style":"curious","visual":"New-case check (lesson compared ore X high-iron/high-harm vs Y; the episode asked 'more iron but arsenic'; here iron % is EQUAL). Two YK.ore hematite rocks A (x 320) and B (x 760), both gauges at the same level on cue 'نسبة'; A gets yellow 'S' and orange 'P' dots on cues 'sulphur' / 'phosphorus'; B stays clean; YK.band 'Same iron %: A or B?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l8'), end: YK.cue('l9')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l9').","tts_text":"اتنين ore نفس نسبة الـ iron، واحد فيه sulphur و phosphorus… أنهي أحسن؟","screen_text":"Same iron %: ore A has S and P, ore B has none. Which?","pause_after_s":2},{"id":"l9","visual":"Answer: ore B grows and glows mint on cue 'التاني'; A's S and P dots pulse coral and A dims on cue 'harmful' (needs tts fix l9: «التاني، لأن مفيهوش harmful elements.»); ONE YK.rightMark by B.","tts_text":"التاني، لأن مفيهوش harmful elements خالص.","screen_text":"B: no harmful elements ✓"},{"id":"l10","visual":"Voiced lock-in: YK.takeaway({title:'Iron: abundance and suitability of iron ore', line:'Not iron % alone: three factors', t, pulse:[{word:'three', at:YK.cue('l10','تلات')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"مش الـ iron بس: تلات حاجات.","screen_text":"Not iron % alone: three factors","pause_after_s":1.5}],"logline":"Iron is the most important metal in heavy industry but only the 4th most abundant element in Earth's crust (after O, Si, Al; 5% by mass); pure iron (90%) comes only in meteorites, and an ore's suitability depends on its iron %, its impurities and its harmful elements (book 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before render.] Frame 0 complete: YK.tube (angle -0.5 rad, x 540, y 1000) holding blue crystals (C.fehling-like blue chips) over a small flame (YK.glowCircle); droplets (YK.drop, cyan) already beading near the cool mouth; YK.band 'Dry crystals. Where's the !{water} from?' (96) at 0. Crystals fade blue → white on cue 'سخّناها'; droplets grow on cue 'مية'.","tts_text":"بلورات ناشفة خالص… سخّناها، فطلعت مية! جت منين؟","screen_text":"Dry crystals. Where's the water from?"},{"id":"l2","visual":"Zoom into one blue crystal (a custom grid of rounded CuSO_4 tiles drawn with YK.roundRect, y 1000; not YK.lattice, which has no units): small H2O molecules (YK.molecule, O red + 2 white H) sit between the units, glowing on cue 'مية'; label 'CuSO_4' (mono 52) on cue 'sulphate'; tag 'inside the crystal' (48) on cue 'crystal'. Prereq chip 'Valency and writing chemical formulas' at line start.","tts_text":"الـ copper two sulphate الأزرق شايل مية جوه الـ crystal نفسه.","screen_text":"Water inside the crystal itself"},{"id":"l3","visual":"YK.termCard({term:'Water of crystallization', def:'A fixed number of water molecules held inside the crystal', keys:['fixed']}) slides up on cue 'water'; 'fixed' pulses on cue 'ثابت'. New term 1.","tts_text":"المية دي اسمها الـ water of crystallization، وعددها ثابت.","screen_text":"Water of crystallization: a fixed number"},{"id":"l4","visual":"Card shrinks up; big YK.formula 'CuSO_4 . !{5}H_2O' (mono 88, y 1000); the dot pulses on cue 'نقطة'; five small YK.molecule H2O (r 26) pop in a row under it (stagger 0.12 s) on cue 'خمس'; one CuSO4 block on cue 'واحد'.","tts_text":"بنكتبها بعد نقطة: خمس molecules مية لكل copper sulphate واحد.","screen_text":"CuSO₄·5H₂O: 5 H₂O per CuSO₄"},{"id":"l5","visual":"Tag 'Hydrated' (56, cyan) beside the formula on cue 'hydrated'; the five H2O icons drift up and off as vapour wisps on cue 'بيطرد'; the formula's '.5H2O' part fades leaving 'CuSO_4' white on cue 'برة'. New term 2.","tts_text":"المادة دي hydrated، والتسخين بيطرد المية دي برة.","screen_text":"Hydrated; heating drives the water off"},{"id":"l6","visual":"Myth (lesson hook's wrong option; no misconception recorded for this concept): A crystal with coral droplets on its surface and pill 'wet outside?'. Small coral pill on cue 'مبلولة' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'جوه' and stays longer on screen. The surface droplets vanish and the inner H2O molecules glow cyan on cue 'جوه'.","tts_text":"ناس فاكرة إن البلورات كانت مبلولة من برة… لأ، المية جوه.","screen_text":"Wet on the outside? ✕  Locked inside ✓"},{"id":"l7","style":"curious","visual":"New-case check (the lesson used CuSO4·5H2O, Na2CO3·10H2O, CoCl2·6H2O, CaSO4 hydrates, limonite and FeSO4·7H2O; not MgSO4). YK.formula 'MgSO_4 . 7H_2O' (mono 80, y 1000) on cue 'magnesium'; the '7' pulses on cue 'سبعة'; a small flame under it on cue 'سخّناه'; YK.band 'Heated: how many H_2O leave?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب الـ magnesium sulphate فيه سبعة بعد النقطة… لو سخّناه، كام molecule هتطلع؟","screen_text":"MgSO₄·7H₂O, heated: how many H₂O leave per MgSO₄?","pause_after_s":2},{"id":"l8","visual":"Answer: seven H2O icons rise off as vapour (stagger 0.1 s) on cue 'سبعة'; the formula drops to 'MgSO_4' on cue 'بتطلع'; ONE YK.rightMark.","tts_text":"سبعة، كل الـ water of crystallization بتطلع بخار.","screen_text":"Seven H₂O per MgSO₄ leave as vapour ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Water of crystallization', line:'Water of crystallization: heat drives it off', formula:'CuSO_4 . 5H_2O', t, pulse:[{word:'heat', at:YK.cue('l9','بالتسخين')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ water of crystallization بالتسخين بتطلع.","screen_text":"Water of crystallization: heat drives it off","pause_after_s":1.5}],"logline":"Dry blue copper(II) sulphate crystals give off water and turn white when heated: the water was locked inside the crystal in a fixed number (CuSO₄·5H₂O), the water of crystallization of a hydrated substance, and heating drives it 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ناشفة خالص سخّناها فطلعت مية جت\nمنين\nالـ copper two sulphate الأزرق شايل مية\nجوه الـ crystal نفسه\nالمية دي اسمها الـ water of\ncrystallization وعددها ثابت\nبنكتبها بعد نقطة خمس molecules مية لكل\ncopper sulphate واحد\nالمادة دي hydrated والتسخين بيطرد المية دي\nبرة\nناس فاكرة إن البلورات كانت مبلولة من برة\nلأ المية جوه\nطب الـ magnesium sulphate فيه سبعة بعد\nالنقطة لو سخّناه كام molecule هتطلع\nسبعة كل الـ water of crystallization بتطلع\nبخار\nالـ water of crystallization بالتسخين\nبتطلع","countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":10},{"id":"chem-s3-en.video-short-fe.ores","kind":"short","version":1,"ord":342,"content_lang":"ar-EG","primary_concept_id":"fe.ores","concepts":[{"concept_id":"fe.ores","role":"primary"}],"title":"Important iron ores","payload":{"title":"Important iron ores","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); ≤ 1 written equation on screen at a time; YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; no furnace zones, slag or limestone (book pp.16-18 only); look at stills before render.] Frame 0 complete: four YK.ore rocks (r 120, label:false) in a 2×2 grid (x 330 / 750, y 820 / 1220): hematite, limonite, magnetite, siderite, each gently rocking (rot from t); YK.band 'Four colours. All !{iron ores}?' (100) at 0 (≤ 6 words, S11). Each rock flashes on its colour word cue: 'أحمر', 'وأصفر', 'وأسود', 'ورمادي'.","tts_text":"أحمر وأصفر وأسود ورمادي… إزاي كلهم iron ores مهمين؟","screen_text":"Four colours. All iron ores?"},{"id":"l2","visual":"Book table row 1 (one row per line, p.16). Grid becomes a 4-row table (top → bottom, row centres y 720 / 960 / 1200 / 1440, 220 px each; one row per line, rows stay): each row = YK.ore r 80 at x 200 (label:false, name:false: the rock's own labels would stack 3 lines under it and overflow the row) + a left-aligned text column at x 330: line 1 'Hematite' (Cairo 1000 52) + 'Fe_2O_3' (YK.formula mono 52) beside it, line 2 the book chemical name (Cairo 800 44). Hematite row slides in; 'Iron III oxide' on cue 'oxide'; red glow on cue 'الدم'. Prereq chip 'Oxidation state in compounds' at line start. Ore table = new term 1 (rows 1-4).","tts_text":"الـ hematite أحمر زي الدم: ده iron three oxide عادي.","screen_text":"Hematite: Fe₂O₃, iron III oxide, blood red"},{"id":"l3","visual":"Row 2 (same row layout): limonite rock + 'Limonite' + '2Fe_2O_3 . 3H_2O' on cue 'limonite'; 'Hydrated iron III oxide' (44) on cue 'hydrated'; the '.3H_2O' part of its formula pulses cyan on cue 'مية'. Prereq chip 'Water of crystallization' at line start.","tts_text":"الـ limonite أصفر، ونفس الـ oxide بس hydrated، شايل مية.","screen_text":"Limonite: 2Fe₂O₃·3H₂O, hydrated, yellow"},{"id":"l4","visual":"Row 3 (same row layout): magnetite rock + 'Magnetite' + 'Fe_3O_4' on cue 'magnetite'; 'Magnetic iron oxide' (44) on cue 'magnetic'; a small YK.magnet slides in from the right and the rock tilts toward it on cue 'بيشده'.","tts_text":"الـ magnetite الأسود هو الـ magnetic iron oxide، والـ magnet بيشده.","screen_text":"Magnetite: Fe₃O₄, magnetic iron oxide, black"},{"id":"l5","visual":"Row 4 (same row layout): siderite rock + 'Siderite' + 'FeCO_3' on cue 'siderite'; 'Iron II carbonate' (44) on cue 'carbonate'; the 'CO_3' in its formula glows gold and a small 'not an oxide' pill (44, at the row's right end x ≤ 972) on cue 'oxide'.","tts_text":"والـ siderite رمادي مصفر، وده iron two carbonate، مش oxide خالص.","screen_text":"Siderite: FeCO₃, iron II carbonate, yellowish grey"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP): hematite and magnetite formulas swapped): Rows 1 and 3 slide next to each other; their formula labels swap places (coral) for a beat. Small coral pill on cue 'بتبدّل' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'أكتر' and stays longer on screen. Labels swap back: 'Fe_3O_4' beside magnetite grows with a tag '7 atoms' (mono 48) and 'Fe_2O_3' beside hematite gets '5 atoms' on cue 'atoms' (counts only; no 'magnetic → more atoms' arrow: that link is false).","tts_text":"ناس بتبدّل الـ hematite بالـ magnetite… لأ، الـ magnetite فيه atoms أكتر.","screen_text":"Hematite = Fe₃O₄? ✕  Magnetite = Fe₃O₄ ✓"},{"id":"l7","style":"curious","visual":"New-case check (the lesson's checks: magnet pick, black Eastern Desert ore, odd-one-out, clue sort; the episode asked limonite's oxidation state). The four rocks back in a row (y 1000, label:true) with a small flame (YK.glowCircle gold → molten, r 60) under each rock on cue 'سخّنا' (no kiln: roasting is another concept); YK.band 'Heated: which loses\\nwater of crystallization?' (80). YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"لو سخّنا الأربعة، مين فيهم هيفقد الـ water of crystallization بتاعته؟","screen_text":"Heated: which one loses water of crystallization?","pause_after_s":2},{"id":"l8","visual":"Answer: vapour wisps rise only from the limonite rock on cue 'limonite'; its '.3H_2O' part fades and the other three stay still on cue 'hydrated'; ONE YK.rightMark.","tts_text":"الـ limonite، عشان هو الـ hydrated الوحيد فيهم.","screen_text":"Limonite: the hydrated one ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Important iron ores', line:'Only siderite is a carbonate; the rest are oxides', t, pulse:[{word:'oxides', at:YK.cue('l9','oxides')}, {word:'carbonate', at:YK.cue('l9','carbonate')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ siderite بس اللي carbonate، والباقي oxides كلهم.","screen_text":"Only siderite is a carbonate; the rest are oxides","pause_after_s":1.5}],"logline":"The book's four iron ores (p.16): hematite Fe₂O₃ (iron III oxide, blood red), limonite 2Fe₂O₃·3H₂O (the same oxide, hydrated, yellow), magnetite Fe₃O₄ (magnetic iron oxide, black) and siderite FeCO₃ (iron II carbonate, yellowish grey): three oxides and one 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(96) at 0. Grey filings shimmer on cue 'برادة'.","tts_text":"برادة iron وقعت في الرمل… تفصلهم إزاي بسرعة؟","screen_text":"Iron in sand: separate it fast?"},{"id":"l2","visual":"Two small cards over the tray: 'Iron: magnetic' (48, cyan) and 'Sand: not magnetic' (48, grey) on cue 'property'. Prereq chip 'Elements, compounds and mixtures' at line start.","tts_text":"السر: استخدم property واحد فيهم عنده والتاني لأ.","screen_text":"Use a property they don't share"},{"id":"l3","visual":"A YK.magnet sweeps over the tray on cue 'بيشد': grey dots fly up and cling, sand stays; YK.pill 'Magnetic separation' (56, cyan) on cue 'magnetic'. Prereq chip 'Magnets and magnetic fields' at line start. New term 1.","tts_text":"ده الـ magnetic separation: الـ magnet بيشد الـ iron والرمل يفضل.","screen_text":"Magnetic separation"},{"id":"l4","visual":"Tray exits; YK.beaker (x 540, y 1150, level 0.7): the surface drawn as a thin bright stretched line on cue 'جلدة'; light pale grains rest on it while dark grains sink to the bottom on cue 'تغطس'; YK.pill 'Surface tension' (56, cyan) on cue 'surface'. New term 2.","tts_text":"والـ surface tension: سطح المية زي جلدة، بيشيل حبيبات خفيفة، والتانية تغطس.","screen_text":"Surface tension: some stay on top"},{"id":"l5","visual":"Beaker exits; grains fall in a stream past a vertical plate marked '+' (x 760): some grains get a small '−' and curve onto the plate on cue 'charge', the rest fall straight into a bin on cue 'يشدها'; YK.pill 'Electric separation' (56, cyan) on cue 'electric'. New term 3.","tts_text":"والـ electric separation: حبيبات بتاخد charge أسهل، فاللوح المشحون يشدها.","screen_text":"Electric separation: a charged plate attracts some"},{"id":"l6","visual":"Myth (the lesson's check mistake; no misconception recorded for this concept): The separated filings on the magnet with a coral 'new substance?' pill. Small coral pill on cue 'جديدة' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'هو' and stays longer on screen. The filings get a YK.label 'Fe' (mono 56) and a tag 'still iron' (48) on cue 'هو'.","tts_text":"ناس فاكرة إن الـ iron بعد الفصل بقى مادة جديدة… لأ، زي ما هو.","screen_text":"A new substance? ✕  Still iron ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson used cork + sand, iron + sand; ore dressing used magnetite + sand). A tray of grey (Fe) and orange-brown (Cu, C.copper) filings mixed (YK.swarm seed 5) on cue 'copper'; tray at y 900; three YK.choice chips stacked top → bottom (x 540, y 1150 / 1260 / 1370; a row of three at 56 px is > 864 px) 'Magnetic', 'Surface tension', 'Electric'; think ring at y 1550; YK.band 'Iron + copper: which method?'. YK.thinkRing(ctx, t, 540, 1550, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"برادة iron وبرادة copper مخلوطين… تفصلهم بإيه؟","screen_text":"Iron + copper filings: which method?","pause_after_s":2},{"id":"l8","visual":"Answer: the magnet sweeps: grey filings jump up, orange ones stay on cue 'magnetic'; 'Magnetic' chip glows mint, others dim; tag 'Cu: not attracted' (48) on cue 'بيتشد'; ONE YK.rightMark.","tts_text":"بالـ magnetic separation، الـ copper مش بيتشد خالص.","screen_text":"Magnetic separation: copper is not attracted ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Separating mixtures', line:'A property they don't share; nothing new forms', t, pulse:[{word:'property', at:YK.cue('l9','property')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"استخدم property مختلفة، ومفيش مادة جديدة.","screen_text":"A property they don't share; nothing new forms","pause_after_s":1.5}],"logline":"A mixture is separated by a physical property its parts don't share: a magnet pulls magnetic particles (magnetic separation), the water's surface holds up some particles (surface tension), a charged plate attracts others (electric separation), and no new substance 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render.] Frame 0 complete: a mine cart (simple steel shape, y 1150) heaped with big YK.ore magnetite rocks (magnetite all through: the concentrating drum pulls magnetic grains, so a hematite ore would be false) (r 90-120, label:false) rolling right toward a closed furnace mouth (steel block, x 900) marked with a coral '?'; YK.band 'Straight into the !{furnace}?' (100) at 0. Rocks bump on cue 'صخور'; the furnace '?' pulses on cue 'furnace'.","tts_text":"الـ ore طالع من المنجم صخور… يدخل الـ furnace على طول؟","screen_text":"Straight into the furnace?"},{"id":"l2","visual":"Cart stops; title 'Ore dressing' (64, y 660) on cue 'dressing' over a progress rail of three grey chips left → right (y 760, Cairo 800 44: 'Crushing' · 'Sintering' · 'Concentrating'; each lights gold on its own line); tag 'physical properties' (48, y 1000) on cue 'physical'. The machines come ONE at a time in the stage centre (y 1050), each replacing the last (S9 one focal object; three stacked machines overflow y 1680). Prereq chip 'Important iron ores' at line start. New term 1 (ore dressing; its three steps = the book list p.17, one per line). [v5 facts fix: the title reads 'Ore dressing part 1: physical properties' (= screen_text); roasting (chemical properties, book p.17) is part 2, next.]","tts_text":"لأ، لازم الأول ore dressing: نحسّن الـ physical properties بتاعته.","screen_text":"Ore dressing part 1: physical properties"},{"id":"l3","visual":"Step 1: chip 'Crushing' lights gold on cue 'crushing'; YK.crusher(ctx, 540, 1080, 520, {p: YK.prog(t, YK.cue('l3','crushing'), YK.cue('l3','بسهولة')), type:'magnetite', t}); tag 'suitable size' (48, y 1420) on cue 'مناسب'.","tts_text":"أولًا الـ crushing: حجم مناسب، عشان يتعمله reduction بسهولة.","screen_text":"Crushing: suitable size, easily reduced"},{"id":"l4","visual":"Fine powder piles under the crusher on cue 'ناعم'; crusher exits up; step 2: chip 'Sintering' lights gold and YK.sinter(ctx, 540, 1080, 760, {p: YK.prog(t, YK.cue('l4','sintering'), YK.cueEnd('l4')), type:'magnetite', t}) fuses the fines into a few equal lumps on cue 'sintering'; tag 'larger, homogeneous lumps' (44, y 1420) on cue 'متجانسة'.","tts_text":"بس الـ crushing بيعمل تراب ناعم، والـ sintering بيجمّعه في كتل أكبر متجانسة.","screen_text":"Sintering: fine dust → larger lumps"},{"id":"l5","visual":"Sinter exits; step 3: chip 'Concentrating' lights gold on cue 'concentrating'; YK.magSeparator(ctx, 540, 1020, 170, {p: YK.prog(t, YK.cue('l5','concentrating'), YK.cue('l5','impurities')), t, labels:{ore:'Ore', waste:'Impurities'}}) (hopper top ≈ y 660, bin labels ≈ y 1490); a small %Fe gauge at x 930 rises on cue 'تعلى'. Prereq chip 'Separating mixtures' at line start (x 108, y 560, above the hopper).","tts_text":"وبعدين الـ concentrating: نشيل الـ impurities، فنسبة الـ iron تعلى.","screen_text":"Concentrating: impurities out, iron % up"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): The sinter belt returns (chip 'Sintering' gold); a coral ghost turns the fines into an orange molten puddle with pill 'melted?'. Small coral pill on cue 'نسيّح' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'بنجمّعه' and stays longer on screen. The puddle vanishes and the solid lumps return on cue 'بنجمّعه'.","tts_text":"ناس فاكرة إن الـ sintering يعني نسيّح الـ ore… لأ، بنجمّعه بس.","screen_text":"Sintering = melting? ✕  Gathering into lumps ✓"},{"id":"l7","style":"curious","visual":"New-case check [needs tts fix l7: «بودرة limonite ناعمة، ومعاها طين كتير… محتاجة أنهي خطوتين؟»; the old 'big rocks + clay → crushing + concentrating, not sintering' contradicts l4 (crushing makes fines that need sintering)]. Lesson: big rocks / fines / furnace dust / sand-rich ore, each with ONE problem; episode: hematite powder; here limonite with TWO problems. A heap of fine yellow limonite powder (YK.swarm dots in C.limonite, y 1050) on cue 'limonite' with brown clay specks mixed in on cue 'طين'; the three rail chips go grey; YK.band 'Fine powder + clay: which two steps?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"بودرة limonite ناعمة، ومعاها طين كتير… محتاجة أنهي خطوتين؟","screen_text":"Fine limonite powder + lots of clay: which two steps?","pause_after_s":2},{"id":"l8","visual":"Answer [needs tts fix l8: «الـ sintering للبودرة، والـ concentrating يشيل الطين.»]: chip 'Sintering' lights mint and the powder fuses into a few lumps on cue 'sintering'; chip 'Concentrating' lights mint and the clay specks fall to a waste bin on cue 'concentrating'; 'Crushing' stays grey; ONE YK.rightMark.","tts_text":"الـ sintering للبودرة، والـ concentrating يشيل الطين.","screen_text":"Sintering (fines) + concentrating (clay out) ✓"},{"id":"l9","visual":"Voiced lock-in: All three rail chips gold, then YK.takeaway({title:'Ore dressing part 1: physical steps', line:'Physical steps done; roasting comes next', t, pulse:[{word:'Physical', at:YK.cue('l9','crushing')}, {word:'roasting', at:YK.cue('l9','roasting')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"بالـ crushing والـ sintering والـ concentrating، وبعدها الـ roasting.","screen_text":"Physical steps done; roasting comes next","pause_after_s":1.5}],"logline":"Ore from the mine is not ready for the furnace: ore dressing first improves its physical properties by crushing (a suitable size, easily reduced), sintering (fine particles gathered into larger homogeneous lumps, not melted) and concentrating (impurities removed, iron % up) (book 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(96) at 0. Powder turns black on cue 'أسود'; wisps thicken on cue 'gas'.","tts_text":"مسحوق أخضر، سخّناه… بقى أسود وطلع منه gas. إيه اللي حصل؟","screen_text":"Heated: green → black + a gas?"},{"id":"l2","visual":"Tube shrinks to the top-left; YK.formula 'CuCO_3 ->[Δ] CuO + CO_2' (mono 64, y 1000, fit 864 px); the reactant splits into two product blocks on cue 'كسّرت'; YK.pill 'Thermal decomposition' (56, gold) on cue 'thermal'. Prereq chip 'Writing and balancing chemical equations' at line start. New term 1.","tts_text":"ده thermal decomposition: الحرارة كسّرت الـ copper carbonate لحاجتين أبسط.","screen_text":"Thermal decomposition: CuCO₃ → CuO + CO₂"},{"id":"l3","visual":"The l2 equation exits first (≤ 1 equation on screen); YK.formula 'Zn + CuSO_4 -> ZnSO_4 + Cu' (mono 60, y 1000); a grey Zn atomDisc slides into the CuSO4 group and an orange Cu atomDisc is pushed out on cue 'بيطرد'; tag 'more active' (44) over Zn on cue 'الأنشط'; YK.pill 'Simple displacement' (56, cyan) on cue 'simple'. New term 2.","tts_text":"في الـ simple displacement، الـ zinc الأنشط بيطرد الـ copper من مكانه.","screen_text":"Simple displacement: Zn + CuSO₄ → ZnSO₄ + Cu"},{"id":"l4","visual":"The l3 equation exits; four coloured tiles A, B, C, D (YK.label 64) pair as AB + CD and swap partners into AD + CB with crossing arcs on cue 'بيبدّلوا'; YK.pill 'Double displacement' (56, violet) on cue 'double'. New term 3.","tts_text":"وفي الـ double displacement، اتنين compounds بيبدّلوا الشركاء.","screen_text":"Double displacement: AB + CD → AD + CB"},{"id":"l5","visual":"Tiles relabel 'HCl + NaOH -> NaCl + H_2O' (mono 56) on cue 'acid'; tags 'salt' and 'water' under the products on cues 'salt' / 'ومية'. Prereq chip 'Acids, bases and salts' at line start.","tts_text":"زي الـ acid والـ base: يدّوا salt ومية.","screen_text":"Acid + base → salt + water"},{"id":"l6","visual":"Myth (the lesson hook's wrong option 'It just melted'; no misconception recorded for this concept): The l1 tube returns small with a coral 'melted?' pill over a green liquid ghost. Small coral pill on cue 'بيسيّح' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'جديدة' and stays longer on screen. The ghost clears to the black solid + CO2 wisps tagged 'new substances' (48) on cue 'جديدة'.","tts_text":"ناس فاكرة إن التسخين بيسيّح المادة وبس… لأ، هنا اتكونت مواد جديدة.","screen_text":"Just melted? ✕  New substances formed ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson checks: CaCO3, Zn(OH)2, Fe + CuSO4, acid + base sorts; not FeCO3). YK.formula 'FeCO_3 ->[Δ] FeO + CO_2' (mono 60, y 1000) builds on cue 'siderite'; three YK.choice chips stacked top → bottom (x 540, y 1160 / 1270 / 1380) 'Thermal decomposition', 'Simple displacement', 'Double displacement' (book names, not shortened); YK.band 'Siderite heated: which type?'. YK.thinkRing(ctx, t, 540, 1560, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"الـ siderite لما يتسخّن بيدّي oxide و carbon dioxide… أنهي نوع؟","screen_text":"Siderite: FeCO₃ → FeO + CO₂. Which type?","pause_after_s":2},{"id":"l8","visual":"Answer: 'Thermal decomposition' chip glows mint on cue 'thermal'; the FeCO3 block splits in two on cue 'اتكسر'; ONE YK.rightMark.","tts_text":"ده thermal decomposition، لأن compound واحد اتكسر لاتنين.","screen_text":"Thermal decomposition: one compound → two ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Types of chemical reactions', line:'Break down · swap one · swap two', t, pulse:[{word:'Break', at:YK.cue('l9','يتكسر')}, {word:'one', at:YK.cue('l9','واحد')}, {word:'two', at:YK.cue('l9','اتنين')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"يتكسر، أو يطرد واحد، أو يبدّلوا اتنين.","screen_text":"Break down · swap one · swap two","pause_after_s":1.5}],"logline":"Three reaction types from their equations: thermal decomposition (heat breaks one compound into simpler substances, as CuCO₃ and siderite do), simple displacement (a more active element replaces a less active one) and double displacement (two compounds swap partners, e.g. acid + base → salt + 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Frame 0 complete: a flat digital scale (custom: YK.roundRect body x 260–820, y 1180–1260, readout window at its front; not YK.balance, which is a two-pan beam) holding a red YK.ore hematite heap (label:false) with YK.label 'Fe_2O_3' (mono 72) above it and a digital readout '? g' (mono 80, gold) blinking; YK.band '1 mole of Fe_2O_3: how many !{grams}?' (88) at 0. Readout blinks on cue 'كام'.","tts_text":"لو عندنا mole واحد من الـ iron three oxide… وزنه كام؟","screen_text":"1 mole of Fe₂O₃: how many grams?"},{"id":"l2","visual":"A YK.swarm of tiny Fe2O3 particle dots pours into a box labelled '1 mol' (52) on cue 'mole'; label 'particles' (44) on cue 'particles'; tag 'fixed number' (48) on cue 'ثابت'. New term 1.","tts_text":"الـ mole يعني عدد particles ثابت.","screen_text":"Mole: a fixed number of particles"},{"id":"l3","visual":"YK.termCard({term:'Molar mass', def:'Sum of the atomic masses in the formula, in g/mol', keys:['Sum']}) on cue 'molar'; mini table 'Fe 56 · O 16' (mono 48) under it on cue 'atomic'. Prereq chip 'Atomic number and mass number' at line start. New term 2.","tts_text":"والـ molar mass: مجموع الـ atomic masses اللي في الـ formula، بالجرام.","screen_text":"Molar mass: sum of atomic masses (g/mol)"},{"id":"l4","visual":"Card shrinks. Two grey Fe atomDiscs (r 70, y 900) pop on cue 'iron'; YK.label '2 × 56' (mono 64) on cue 'وخمسين'; '= 112' on cue 'وتناشر'. Prereq chip 'Valency and writing chemical formulas' at line start.","tts_text":"اتنين iron، كل واحد ستة وخمسين، يعني مية وتناشر.","screen_text":"Fe: 2 × 56 = 112"},{"id":"l5","visual":"Three red O atomDiscs (r 56, y 1150) pop on cue 'oxygen'; '3 × 16' on cue 'ستاشر'; '= 48' on cue 'وأربعين'.","tts_text":"وتلاتة oxygen، كل واحد ستاشر، يعني تمانية وأربعين.","screen_text":"O: 3 × 16 = 48"},{"id":"l6","visual":"112 and 48 slide together into '160 g/mol' (mono 96, gold) on cue 'وستين'; the l1 readout flashes back with '160 g' on the same cue 'وستين' (not 'molar': the number must not show before it is spoken).","tts_text":"يعني الـ molar mass هنا مية وستين.","screen_text":"M(Fe₂O₃) = 160 g/mol"},{"id":"l7","visual":"Myth (the lesson hook's wrong option (counting atoms); no misconception recorded for this concept): Coral sum '2 + 3 = 5' over the atom discs. Small coral pill on cue 'خمسة' + YK.wrongMark on YK.cue('l7','لأ',1) (k=1: 'وتلاتة' contains 'لا' and is hit first), both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'الأوزان' and stays longer on screen. It is replaced by '2 × 56 + 3 × 16' (mint) on cue 'الأوزان'.","tts_text":"ناس بتعد الـ atoms، اتنين وتلاتة يبقوا خمسة… لأ، احسب الأوزان.","screen_text":"2 + 3 = 5? ✕  Add the masses ✓"},{"id":"l8","style":"curious","visual":"New-case check [needs tts fix l8: «الـ sulphur dioxide: الـ sulphur اتنين وتلاتين… الـ molar mass كام؟» (Egyptian order for 32, as in l9)]. Lesson used Fe2O3, limonite, FeCO3, CO2; not SO2. YK.molecule with custom atoms (no 'SO2' preset): atoms:[{el:'S', x:0, y:0}, {el:'O', x:-1.7, y:0.9}, {el:'O', x:1.7, y:0.9}], bonds:[[0,1,2],[0,2,2]], r 60, y 1000, on cue 'dioxide'; tags 'S = 32', 'O = 16' (mono 48) on cue 'وتلاتين'; YK.band 'SO_2: molar mass?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l8'), end: YK.cue('l9')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l9').","tts_text":"الـ sulphur dioxide: الـ sulphur اتنين وتلاتين… الـ molar mass كام؟","screen_text":"SO₂ (S = 32, O = 16): molar mass?","pause_after_s":2},{"id":"l9","visual":"Answer, in spoken order: total '64 g/mol' (mono 88, gold, y 1300) on cue 'أربعة'; then '32' under S on cue 'وتلاتين'; '2 × 16' under the O pair on cue 'مرتين'; ONE YK.rightMark by the total.","tts_text":"أربعة وستين: اتنين وتلاتين، وستاشر مرتين.","screen_text":"64 g/mol = 32 + 2 × 16 ✓"},{"id":"l10","visual":"Voiced lock-in: YK.takeaway({title:'Molar mass', line:'Multiply by the atoms, then add the masses', formula:'M = Σ (atoms × atomic mass)', t, pulse:[{word:'add', at:YK.cue('l10','واجمع')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"اضرب في عدد الـ atoms، واجمع الأوزان.","screen_text":"Multiply by the atoms, then add the masses","pause_after_s":1.5}],"logline":"The molar mass is the sum of the atomic masses in a formula, in g/mol: multiply each atomic mass by its number of atoms, then add (Fe₂O₃: 2 × 56 + 3 × 16 = 160 g/mol); counting atoms instead of masses is the 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عندنا mole واحد من الـ iron three oxide\nوزنه كام\nالـ mole يعني عدد particles ثابت\nوالـ molar mass مجموع الـ atomic masses\nاللي في الـ formula بالجرام\nاتنين iron كل واحد ستة وخمسين يعني مية\nوتناشر\nوتلاتة oxygen كل واحد ستاشر يعني تمانية\nوأربعين\nيعني الـ molar mass هنا مية وستين\nناس بتعد الـ atoms اتنين وتلاتة يبقوا خمسة\nلأ احسب الأوزان\nالـ sulphur dioxide الـ sulphur اتنين\nوتلاتين الـ molar mass كام\nأربعة وستين اتنين وتلاتين وستاشر مرتين\nاضرب في عدد الـ atoms واجمع الأوزان","countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":15},{"id":"chem-s3-en.video-short-stoich.mass-percentage","kind":"short","version":1,"ord":352,"content_lang":"ar-EG","primary_concept_id":"stoich.mass-percentage","concepts":[{"concept_id":"stoich.mass-percentage","role":"primary"}],"title":"Mass percentage of an element","payload":{"title":"Mass percentage of an element","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); ≤ 1 written equation on screen at a time; YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; no furnace zones, slag or limestone (book pp.16-18 only); look at stills before render.] Frame 0 complete: a big YK.ore hematite rock (r 170, y 950, label:true) with a custom pie ring around it (two arcs; the kit has no pie), its share hidden behind a '?' (mono 96, gold); YK.band 'Pure Fe_2O_3: what !{%} is iron?' (96) at 0. The '?' pulses on cue 'المية'.","tts_text":"حتة hematite نقي… كام في المية منها iron بالظبط؟","screen_text":"Pure hematite, Fe₂O₃: what % is iron?"},{"id":"l2","visual":"Title 'Mass percentage' (60, y 600) on cue 'mass'; a stacked fraction builds (custom layout, not one formula line: on one line it is ≈ 1500 px): '% =' (mono 64, x 140, y 1000) + numerator 'mass of element in 1 mol' (Cairo 800 48, centred x 600, y 950) on cue 'element'. Prereq chip 'Molar mass' at line start. New term 1.","tts_text":"الـ mass percentage: كتلة الـ element في الـ mole الواحد،","screen_text":"Mass of the element in 1 mol"},{"id":"l3","visual":"Fraction bar + denominator 'molar mass' (Cairo 800 48, y 1060) on cue 'molar'; '× 100' (mono 64, right of the bar, x ≤ 960) on cue 'مضروبة'.","tts_text":"على الـ molar mass، وبعدين مضروبة في مية.","screen_text":"÷ molar mass × 100"},{"id":"l4","visual":"The fraction shrinks up (y 640, numerator/denominator 44). Two Fe atomDiscs (y 1000) on cue 'iron'; '2 × 56 = 112' (mono 64) on cue 'وتناشر'.","tts_text":"الـ iron: اتنين في ستة وخمسين، يعني مية وتناشر.","screen_text":"Fe: 2 × 56 = 112"},{"id":"l5","visual":"'112 / 160 × 100' (mono 64, y 1200) on cue 'وستين'; the l1 pie fills gold to 70% and '70%' (mono 96) on cue 'سبعين'.","tts_text":"على مية وستين، مضروبة في مية… سبعين في المية.","screen_text":"112 ÷ 160 × 100 = 70%"},{"id":"l6","visual":"Myth (the lesson's check mistake 'That counts atoms (1 out of 5)'; no misconception recorded for this concept): Coral pie at 40% with pill '2 of 5 atoms'. Small coral pill on cue 'atoms' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'بالكتلة' and stays longer on screen. The pie springs back to 70% on cue 'بالكتلة'.","tts_text":"ناس بتقول اتنين من خمس atoms، يعني أربعين في المية… لأ، احسب بالكتلة.","screen_text":"2 of 5 atoms = 40%? ✕  Use masses ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson worked Fe3O4 72.4% and checked FeCO3 48.3%; not FeO). A black FeO heap (y 1000) with YK.label 'FeO' (mono 72) on cue 'oxide'; tag 'M = 72' (mono 52) on cue 'وسبعين'; the 70% Fe2O3 pie stays small at the left as reference; YK.band 'FeO: more or less than 70% iron?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"الـ iron two oxide، وزن الـ mole اتنين وسبعين… النسبة أكتر ولا أقل؟","screen_text":"FeO (M = 72): more or less than 70% iron?","pause_after_s":2},{"id":"l8","visual":"Answer: '56 / 72 × 100 ≈ 77.8%' (mono 60) on cue 'وخمسين'; FeO pie fills past the 70% reference on cue 'تمانية'; ONE YK.rightMark on cue 'أكتر'.","tts_text":"أكتر: ستة وخمسين على اتنين وسبعين، حوالي تمانية وسبعين في المية.","screen_text":"56 ÷ 72 × 100 ≈ 77.8%: more ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Mass percentage of an element', line:'Use masses, not atom counts', formula:'% Fe = mass of Fe ÷ M × 100', t, pulse:[{word:'masses', at:YK.cue('l9','الكتلة')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"احسب الكتلة، مش عدد الـ atoms اللي فيه.","screen_text":"Use masses, not atom counts","pause_after_s":1.5}],"logline":"Mass percentage of an element = mass of the element in one mole ÷ molar mass × 100: pure Fe₂O₃ is 112 ÷ 160 × 100 = 70% iron; use masses, not the number of 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hematite نقي كام في المية منها iron\nبالظبط\nالـ mass percentage كتلة الـ element في\nالـ mole الواحد\nعلى الـ molar mass وبعدين مضروبة في مية\nالـ iron اتنين في ستة وخمسين يعني مية\nوتناشر\nعلى مية وستين مضروبة في مية سبعين في المية\nناس بتقول اتنين من خمس atoms يعني أربعين\nفي المية لأ احسب بالكتلة\nالـ iron two oxide وزن الـ mole اتنين\nوسبعين النسبة أكتر ولا أقل\nأكتر ستة وخمسين على اتنين وسبعين حوالي\nتمانية وسبعين في المية\nاحسب الكتلة مش عدد الـ atoms اللي فيه","countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":16},{"id":"chem-s3-en.video-short-fe.roasting","kind":"short","version":3,"ord":354,"content_lang":"ar-EG","primary_concept_id":"fe.roasting","concepts":[{"concept_id":"fe.roasting","role":"primary"}],"title":"Roasting of iron ore","payload":{"title":"Roasting of iron ore","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); ≤ 1 written equation on screen at a time; YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; no furnace zones, slag or limestone (book pp.16-18 only); look at stills before render.] Frame 0 complete: YK.kiln(ctx, 540, 1050, 820, 300, {t, heat:1, gases:[]}) turning with siderite chunks tumbling; a %Fe gauge at the right (x 900) climbing from '48.5%' to '69.6%' (YK.counter, mono 64) on a loop; YK.band '48.5% → 69.6%. No !{iron} added?' (88) at 0. Gauge flashes on cue 'سبعين' [needs tts fix l1: «نسبة الـ iron بتعلى لحوالي سبعين… من غير ما نزود حاجة!» (the book value is 69.6%, not 70)]. [v5 facts fix: oxygen IS added in roasting (FeO + O2 → Fe2O3), so the hook says no IRON added; voice ends «من غير ما نزود iron!».]","tts_text":"نسبة الـ iron بتعلى لحوالي سبعين… من غير ما نزود iron!","screen_text":"48.5% → 69.6% iron. No iron added?"},{"id":"l2","visual":"Kiln flame flares on cue 'جامد'; small air arrows (cyan) blow into the kiln mouth on cue 'الهوا'; YK.pill 'Roasting' (60, gold) on cue 'roasting'. Prereq chip 'Ore dressing: crushing, sintering, concentrating' at line start. New term 1.","tts_text":"الـ roasting: نسخّن الـ ore جامد في الهوا.","screen_text":"Roasting: strongly heated in air"},{"id":"l3","visual":"The kiln's gas labels switch on with gases:['H_2O'] on cue 'ينشّف' (frame 0 had gases:[]); the gauge ticks up on cue 'تعلى'; tag '(a) drying' (48) on cue 'الأول'. Prereq chip 'Mass percentage of an element' at line start.","tts_text":"الأول: ينشّف الـ ore، فنسبة الـ iron تعلى.","screen_text":"(a) Drying the ore → iron % up"},{"id":"l4","visual":"Kiln shrinks to the top. ONE formula chain, not two equations (≤ 1 written equation on screen; the book equation of this short is l8): 'FeCO_3 ->[Δ] FeO' (mono 60, y 1000) on cue 'siderite'; '+ CO_2' drifts off upward as a gas wisp on cue 'dioxide'; the chain extends '-> Fe_2O_3' on cue 'oxygen' with a cyan O_2 joining. Prereq chip 'Types of chemical reactions' at line start (thermal decomposition).","tts_text":"الـ siderite يطلّع carbon dioxide، والـ iron two oxide ياخد oxygen من الهوا.","screen_text":"FeCO₃ → FeO + CO₂ → Fe₂O₃"},{"id":"l5","visual":"The chain exits. Prereq chip 'Oxidation and reduction by oxygen' at line start. Yellow S and orange P dots in the ore pick up red O dots and become 'SO_2' (leaves as a gas wisp) and 'P_2O_5' (stays as a small solid flake) on cues 'sulphur' / 'phosphorus' (book: P2O5 is a solid); tag '(b) oxidation' (48) on cue 'oxidation'.","tts_text":"تانيًا، oxidation للـ impurities، زي الـ sulphur والـ phosphorus كمان.","screen_text":"(b) Oxidation of impurities: S and P"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): Coral pill 'reduction?' over the kiln; a ghost Fe bar appears coming out. Small coral pill on cue 'reduction' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'الهوا' and stays longer on screen. The ghost vanishes; air arrows and 'Fe_2O_3' (still an oxide) return on cue 'الهوا'.","tts_text":"ناس فاكرة إن الـ roasting reduction… لأ، ده تسخين في الهوا.","screen_text":"Roasting = reduction? ✕  Heating in air ✓"},{"id":"l7","style":"curious","visual":"New-case check (this short worked siderite; the lesson's own check used limonite only for 'why does % rise', the episode used damp hematite). YK.ore limonite (r 130, y 950, label:true) with tag '40% Fe (roasting equation, p.17)' (mono 56, book p.17) on cue 'أربعين'; the gauge resets to 40% with an up/down arrow pair on cue 'تعلى'; YK.band 'Roasting equation: 40% → up or down?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"في معادلة الـ roasting، الـ limonite مكتوب عليه أربعين في المية iron… بعد الـ roasting، النسبة تعلى ولا تقل؟","screen_text":"Roasting equation: limonite (40% Fe) → iron % up or down?","pause_after_s":2},{"id":"l8","visual":"Answer (the short's one book equation; the kiln is hidden): YK.formula '2Fe_2O_3 . 3H_2O ->[Δ] 2Fe_2O_3 + 3H_2O' (mono 48) on cue 'water'; vapour wisps rise on cue 'بخار'; gauge climbs 40% → 69.6% on cue 'تعلى'; ONE YK.rightMark.","tts_text":"تعلى، لأن الـ water of crystallization طلعت بخار.","screen_text":"Up to 69.6%: water of crystallization leaves ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Roasting of iron ore', line:'Same iron, less mass: iron % rises', t, pulse:[{word:'Same', at:YK.cue('l9','ثابت')}, {word:'rises', at:YK.cue('l9','تعلى')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ iron ثابت، والكتلة بتقل، فالنسبة تعلى.","screen_text":"Same iron, less mass: iron % rises","pause_after_s":1.5}],"logline":"Roasting strongly heats the ore in air (book p.17): it dries the ore and expels gases so the iron % rises (siderite FeCO₃ → FeO + CO₂, then FeO + O₂ → Fe₂O₃; limonite (40% Fe in the p.17 roasting equation) → Fe₂O₃ 69.6%) and oxidizes impurities such as sulphur and phosphorus; it is not 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الـ iron بتعلى لحوالي سبعين من غير ما\nنزود iron\nالـ roasting نسخّن الـ ore جامد في الهوا\nالأول ينشّف الـ ore فنسبة الـ iron تعلى\nالـ siderite يطلّع carbon dioxide والـ\niron two oxide ياخد oxygen من الهوا\nتانيًا oxidation للـ impurities زي الـ\nsulphur والـ phosphorus كمان\nناس فاكرة إن الـ roasting reduction لأ ده\nتسخين في الهوا\nفي معادلة الـ roasting الـ limonite مكتوب\nعليه أربعين في المية iron بعد الـ roasting\nالنسبة تعلى ولا تقل\nتعلى لأن الـ water of crystallization طلعت\nبخار\nالـ iron ثابت والكتلة بتقل فالنسبة تعلى","countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":17},{"id":"chem-s3-en.video-short-fe.blast-furnace-reduction","kind":"short","version":1,"ord":356,"content_lang":"ar-EG","primary_concept_id":"fe.blast-furnace-reduction","concepts":[{"concept_id":"fe.blast-furnace-reduction","role":"primary"}],"title":"Reduction in the blast furnace","payload":{"title":"Reduction in the blast furnace","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); ≤ 1 written equation on screen at a time; YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; no furnace zones, slag or limestone (book pp.16-18 only); look at stills before render.] Frame 0 complete: YK.furnace(ctx, 290, 560, 500, 1000, {type:'blast', t, heat:0.6, flow:0, labels:false}) on the left half; on the right (x 800, y 900) a big Fe2O3 group (2 grey Fe + 3 red O atomDiscs) with the O discs pulsing; YK.band 'Who takes the !{oxygen}?' (100) at 0. O discs glow on cue 'oxygen'; label 'Blast furnace' (52, above the furnace top) on cue 'blast' [needs tts fix l1: «مين بياخد الـ oxygen من الـ iron oxide في الـ blast furnace؟», so 'blast furnace' and 'coke' are not both new in l2 (S3a)].","tts_text":"مين بياخد الـ oxygen من الـ iron oxide في الـ blast furnace؟","screen_text":"Who takes the oxygen from Fe₂O₃?"},{"id":"l2","visual":"[needs tts fix l2: «الـ coke بيتحرق الأول، ويطلع carbon dioxide.»] Furnace heat ramps 0.6 → 1 on cue 'بيتحرق'; dark coke lumps glow in the charge; right panel (y 900): a coke lump (YK.rock, C.atomC) + YK.molecule O2 → YK.molecule CO2 on cue 'dioxide' (molecules, no written equation: the one equation is l4); YK.pill 'Coke' (56) on cue 'coke'. Prereq chip 'Roasting of iron ore' at line start. New terms 1 (blast furnace, l1) and 2 (coke).","tts_text":"الـ coke بيتحرق الأول، ويطلع carbon dioxide.","screen_text":"Coke burns → CO₂"},{"id":"l3","visual":"[needs tts fix l3: «الـ carbon dioxide يقابل coke سخن، ويطلع منهم carbon monoxide.»] Right panel: the CO2 molecule meets a second glowing coke lump on cue 'يقابل' and two YK.molecule CO come out on cue 'monoxide'; the furnace flow ramps 0 → 1 with cyan CO wisps rising (labels:true from here; the kit draws the book's '> 700°C' only).","tts_text":"الـ carbon dioxide يقابل coke سخن، ويطلع منهم carbon monoxide.","screen_text":"CO₂ + hot coke → CO"},{"id":"l4","visual":"The molecules exit; the ONE written equation, in two rows (mono 56, x 108–972): '3CO + Fe_2O_3' (y 760) / '->[> 700 °C] 2Fe + 3CO_2' (y 850) on cue 'reducing'; on the right group (y 1150) three cyan CO dots each grab one red O (becoming CO2) on cue 'بياخد', leaving two grey Fe on cue 'لوحده'; tag 'reducing agent' (48) on cue 'agent'. Prereq chip 'Oxidation and reduction by oxygen' at line start (reducing agent is a prerequisite word, not a new term).","tts_text":"والـ carbon monoxide هو الـ reducing agent: بياخد الـ oxygen ويفضل الـ iron لوحده.","screen_text":"3CO + Fe₂O₃ → 2Fe + 3CO₂"},{"id":"l5","visual":"The '> 700 °C' on the reduction arrow glows gold (mono) on cue 'سبعمية'; molten iron taps from the furnace bottom (tap 0 → 1) on cue 'درجة'.","tts_text":"ده فوق سبعمية درجة.","screen_text":"Above 700 °C"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A coral ghost arrow goes straight from a coke lump to Fe2O3 with pill 'coke?'. Small coral pill on cue 'بنفسه' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'مصدر' and stays longer on screen. The ghost is replaced by coke → CO → Fe2O3 arrows (mint) and tag 'Coke: source of CO' (48) on cue 'مصدر'.","tts_text":"ناس فاكرة إن الـ coke بيعمل reduction بنفسه… لأ، مصدر الـ carbon monoxide بس.","screen_text":"Coke reduces by itself? ✕  CO does ✓"},{"id":"l7","style":"curious","visual":"New-case check [needs tts fix l7: «لو مفيش coke، وضخينا carbon monoxide سخن… الـ iron هيطلع؟»; 'hot' keeps the book condition: CO reduces above 700 °C]. Lesson checked CuO + CO and the exam 'role of coke'; the episode asked 'no O2 into the furnace'. The furnace dims to 30% (the kit cannot remove its coke) and a coral ✕ outline crosses a coke lump on cue 'مفيش'; a pipe feeds hot cyan CO into the right-panel Fe2O3 group with tag '> 700 °C' (mono 48) on cue 'سخن'; YK.band 'No coke, hot CO: iron?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"لو مفيش coke، وضخينا carbon monoxide سخن… الـ iron هيطلع؟","screen_text":"No coke, hot CO (> 700 °C) pumped in: iron?","pause_after_s":2},{"id":"l8","visual":"Answer: CO reaches the ore, the O discs leave as CO2 on cue 'reducing'; two grey Fe remain on cue 'أصلًا'; ONE YK.rightMark on cue 'أيوه'.","tts_text":"أيوه، الـ carbon monoxide هو الـ reducing agent أصلًا.","screen_text":"Yes: CO is the reducing agent ✓"},{"id":"l9","visual":"Voiced lock-in [needs tts fix l9: «الـ carbon monoxide هو الـ reducing agent، مش الـ coke.»; the old 'CO takes all the oxygen' is true only for this one equation and drops the book idea: CO is the reducing agent, coke its source]: YK.takeaway({title:'Reduction in the blast furnace', line:'CO, not coke, is the reducing agent', formula:'3CO + Fe_2O_3 -> 2Fe + 3CO_2', t, pulse:[{word:'CO', at:YK.cue('l9','monoxide')}, {word:'reducing', at:YK.cue('l9','reducing')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ carbon monoxide هو الـ reducing agent، والـ coke لأ.","screen_text":"CO, not coke, is the reducing agent","pause_after_s":1.5}],"logline":"In the blast furnace coke burns to CO₂, CO₂ meets more hot coke and gives CO, and carbon monoxide, the reducing agent, takes the oxygen from Fe₂O₃ above 700 °C: coke itself does not reduce the ore, it is the source of CO (book 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render.] Frame 0 complete: a stove burner ring (steel, y 1150) with a steady blue flame crown (seeded flicker from t); YK.band 'The blue flame: what is !{burning}?' (96) at 0. Flame flares on cue 'الزرقا'.","tts_text":"النار الزرقا في بوتاجاز البيت… بتحرق إيه بالظبط؟","screen_text":"The blue flame: what is burning?"},{"id":"l2","visual":"A pipe line runs from an underground pocket (dark layer, y 1500) up to the burner on cue 'الأرض'; YK.pill 'Natural gas' (60, cyan) on cue 'natural'. New term 1.","tts_text":"ده الـ natural gas، من تحت الأرض.","screen_text":"Natural gas: from underground"},{"id":"l3","visual":"Pocket zooms into a horizontal bar: 93% 'Methane' (cyan) + 7% 'Other gases' (grey) on cue 'وتسعين'; YK.label 'CH_4' (mono 64) on cue 'methane'; footnote 'Book p.18' (40, 60%). New term 2.","tts_text":"وأغلبه methane: تلاتة وتسعين في المية حسب الكتاب.","screen_text":"93% methane, CH₄"},{"id":"l4","visual":"YK.molecule CH4 (C dark grey centre, 4 white H around, y 1000) builds: C on cue 'carbon', the four H on cue 'hydrogen'. Prereq chip 'Valency and writing chemical formulas' at line start.","tts_text":"الـ methane فيه carbon واحد، وأربعة hydrogen حواليه.","screen_text":"CH₄: 1 C + 4 H"},{"id":"l5","visual":"YK.termCard({term:'Hydrocarbon', def:'A compound made of carbon and hydrogen only', keys:['only']}) on cue 'hydrocarbon'; 'only' pulses on cue 'وبس'. New term 3.","tts_text":"الـ hydrocarbon: compound فيه carbon و hydrogen وبس.","screen_text":"Hydrocarbon: C and H only"},{"id":"l6","visual":"Card shrinks; the CH4 molecule returns centre with a gold '1 C' tag on cue 'واحد'; title 'simplest' (56) on cue 'أبسط'.","tts_text":"والـ methane أبسط hydrocarbon: carbon واحد بس.","screen_text":"Methane: the simplest hydrocarbon"},{"id":"l7","visual":"Myth (the lesson's check mistake (compounds with O sorted as hydrocarbons); no misconception recorded for this concept): A sugar cube (custom white YK.roundRect with facets; YK.ICONS has no sugar) with tags 'C', 'H' and a hidden 'O'; coral pill 'hydrocarbon?'. Small coral pill on cue 'hydrocarbon' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'oxygen' and stays longer on screen. The 'O' tag pops red on cue 'oxygen' and the pill becomes 'not a hydrocarbon' (44).","tts_text":"ناس فاكرة إن السكر hydrocarbon عشان فيه carbon و hydrogen… لأ، فيه oxygen كمان.","screen_text":"Sugar (C, H and O): hydrocarbon? ✕"},{"id":"l8","style":"curious","visual":"New-case check (lesson sorted CH4, CO2, C2H5OH-type formulas; not butane). A gas cylinder (custom steel capsule shape, y 1000; YK.ICONS has no cylinder) on cue 'أنبوبة'; YK.label 'C_4H_10' (mono 80) on cue 'formula'; YK.band 'Butane, C_4H_10: a hydrocarbon?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l8'), end: YK.cue('l9')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l9').","tts_text":"أنبوبة البوتاجاز فيها butane… بص على الـ formula: hydrocarbon ولا لأ؟","screen_text":"Butane, C₄H₁₀: a hydrocarbon?","pause_after_s":2},{"id":"l9","visual":"Answer: 'C_4' and 'H_10' glow mint on cues 'carbon' / 'hydrogen'; a tiny CH4 beside it on cue 'methane'; ONE YK.rightMark on cue 'أيوه'.","tts_text":"أيوه، فيه carbon و hydrogen بس، زي الـ methane بالظبط.","screen_text":"Yes: C and H only ✓"},{"id":"l10","visual":"Voiced lock-in: YK.takeaway({title:'Natural gas (methane)', line:'Mostly methane, the simplest hydrocarbon', formula:'CH_4', t, pulse:[{word:'methane', at:YK.cue('l10','methane')}, {word:'hydrocarbon', at:YK.cue('l10','hydrocarbon')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ natural gas أغلبه methane: أبسط hydrocarbon خالص.","screen_text":"Natural gas: mostly methane, the simplest hydrocarbon","pause_after_s":1.5}],"logline":"Natural gas, the fuel of many Egyptian kitchens and of the Midrex furnace, comes from underground and is 93% methane, CH₄: one carbon and four hydrogen atoms, the simplest hydrocarbon (a compound of carbon and hydrogen 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furnace","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); ≤ 1 written equation on screen at a time; YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; no furnace zones, slag or limestone (book pp.16-18 only); look at stills before render.] Frame 0 complete: YK.furnace(ctx, 300, 560, 480, 1000, {type:'midrex', t, heat:0.7, flow:0, labels:false, reformer:true}) on the left; a coke heap on the right (x 800, y 1000) crossed out by a coral ✕ outline (no stamp); YK.band 'Iron without !{coke}?' (104) at 0. Coke heap shakes on cue 'coke'.","tts_text":"ينفع نطلّع iron من الـ ore من غير coke خالص؟","screen_text":"Iron without coke?"},{"id":"l2","visual":"Coke heap exits; a gas pipe feeds the furnace's reformer box on cue 'natural'; label 'Midrex furnace' (56) on cue 'Midrex'; tag 'natural gas (93% methane)' (44). Prereq chip 'Natural gas (methane)' at line start. New term 1.","tts_text":"أيوه، الـ Midrex furnace بيشتغل بالـ natural gas بداله.","screen_text":"Midrex furnace: natural gas (93% methane)"},{"id":"l3","visual":"Right panel: the kit's reformer box glows (furnace highlight:'gas'); a formula chain 'CH_4 -> CO + H_2' (mono 60, y 760) on cue 'methane' (chain, not the balanced book equation: the short's one equation is l7); the products get a bracket 'water gas' (52, cyan) on cue 'water'; furnace flow ramps 0 → 1 (labels:true: the kit draws 'CO + H2') on cue 'hydrogen'. New term 2.","tts_text":"الـ methane بيدّي water gas، يعني carbon monoxide و hydrogen مع بعض.","screen_text":"Natural gas → water gas (CO + H₂)"},{"id":"l4","visual":"Right: an Fe2O3 group (y 1150); cyan CO dots and white H2 dots each grab one red O on cue 'بياخدوا'; tag 'two reducing agents' (48) on cue 'reducing'. Prereq chip 'Reduction in the blast furnace' at line start.","tts_text":"والاتنين reducing agents: بياخدوا الـ oxygen من الـ ore سوا.","screen_text":"CO and H₂: two reducing agents"},{"id":"l5","visual":"Myth (concept misconception 1 (TOP)): A coral ghost arrow from a CH4 molecule straight to Fe2O3 with pill 'methane?'. Small coral pill on cue 'methane' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'منه' and stays longer on screen. The ghost is replaced by CH4 → reformer → CO + H2 → Fe2O3 arrows (mint) on cue 'منه'.","tts_text":"ناس فاكرة إن الـ methane بيعمل reduction بنفسه… لأ، الـ water gas اللي منه.","screen_text":"Methane reduces? ✕  Water gas does ✓"},{"id":"l6","style":"curious","visual":"New-case check (the products were not shown yet in this short; lesson checks: NiO + H2, role of natural gas, coke in Midrex; episode: magnetite count). The CO and H2 dots each holding one red O, frozen with a '?' (mono 72) beside each on cue 'oxygen'; YK.band 'CO + O → ?   H_2 + O → ?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l6'), end: YK.cue('l7')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l7').","tts_text":"الـ carbon monoxide والـ hydrogen خدوا الـ oxygen… هيتحولوا لإيه؟","screen_text":"CO and H₂ take the oxygen: what do they become?","pause_after_s":2},{"id":"l7","visual":"Answer: '?' marks become 'CO_2' on cue 'dioxide'; 'H_2O' with a vapour wisp appears on cue 'بخار'; then the ONE book equation in two rows (mono 56, x 108–972): '2Fe_2O_3 + 3CO + 3H_2' (y 1300) / '->[Δ] 4Fe + 3CO_2 + 3H_2O' (y 1390); grey solid Fe leaves the furnace bottom; ONE YK.rightMark.","tts_text":"الـ carbon monoxide يبقى carbon dioxide، والـ hydrogen يبقى بخار مية.","screen_text":"CO → CO₂ · H₂ → H₂O (vapour) ✓"},{"id":"l8","visual":"Voiced lock-in [needs tts fix l8: «الـ water gas اللي من الـ natural gas هو اللي بيعمل reduction.»; the old line 'Natural gas: source of water gas' never said what reduces, the top misconception's point]: YK.takeaway({title:'Reduction in the Midrex furnace', line:'Water gas (CO + H_2) reduces the ore', formula:'CO + H_2', t, pulse:[{word:'Water', at:YK.cue('l8','water')}, {word:'reduces', at:YK.cue('l8','reduction')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ water gas بيعمل reduction للـ ore بنفسه.","screen_text":"Water gas (CO + H₂) reduces the ore","pause_after_s":1.5}],"logline":"The Midrex furnace reduces iron ore with no coke: natural gas (93% methane) is turned into water gas, a mixture of CO and H₂, and both take the oxygen from Fe₂O₃, leaving CO₂ and water vapour (book p.18). Methane itself never meets the 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نطلّع iron من الـ ore من غير coke\nخالص\nأيوه الـ Midrex furnace بيشتغل بالـ\nnatural gas بداله\nالـ methane بيدّي water gas يعني carbon\nmonoxide و hydrogen مع بعض\nوالاتنين reducing agents بياخدوا الـ\noxygen من الـ ore سوا\nناس فاكرة إن الـ methane بيعمل reduction\nبنفسه لأ الـ water gas اللي منه\nالـ carbon monoxide والـ hydrogen خدوا الـ\noxygen هيتحولوا لإيه\nالـ carbon monoxide يبقى carbon dioxide\nوالـ hydrogen يبقى بخار مية\nالـ water gas بيعمل reduction للـ ore\nبنفسه","countable":true,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":20},{"id":"chem-s3-en.video-short-fe.steel-production","kind":"short","version":1,"ord":362,"content_lang":"ar-EG","primary_concept_id":"fe.steel-production","concepts":[{"concept_id":"fe.steel-production","role":"primary"}],"title":"Iron production and steel","payload":{"title":"Iron production and 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Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); ≤ 1 written equation on screen at a time; YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); English only, LTR; key content x 108-972 / y 240-1680; every needle below is a whole word of that line's tts_text; no furnace zones, slag or limestone (book pp.16-18 only); look at stills before render.] Frame 0 complete: left YK.furnace(ctx, 140, 620, 380, 760, {type:'blast', t, tap:1, labels:false}) with a molten tap stream; right a car silhouette (steel grey, x 760, y 1000); a coral '?' between them; YK.band 'Iron out. Steel in cars. !{Why}?' (96) at 0. Tap glows on cue 'iron'; the car shines on cue 'steel'. Furnace at x 140 so its air pipes stay inside x >= 108.","tts_text":"الـ blast furnace بيطلّع iron… والعربية steel. إيه الفرق؟","screen_text":"Iron out. Steel in cars. Why?"},{"id":"l2","visual":"A three-step rail (top → bottom): 'Ore dressing' and 'Reduction' greyed (done), 'Iron production' lights gold on cue 'production'; tag 'Cast iron' (52) under it on cue 'cast'. Prereq chip 'Reduction in the blast furnace' at line start. New term: cast iron only.","tts_text":"التالت: الـ iron production، زي الـ cast iron.","screen_text":"Iron production: cast iron"},{"id":"l3","visual":"Second tag 'Steel' (52) joins 'Cast iron' under 'Iron production' on cue 'steel' (the rail now reads 'Iron production: cast iron, steel' and stays as the list); a small car icon pulses beside 'Steel' on cue 'العربية'. New term: steel.","tts_text":"وكمان الـ steel، اللي في العربية.","screen_text":"… and steel"},{"id":"l4","visual":"Rail exits; a ladle of molten iron (y 1000) with grey impurity specks; specks lift out and fade on cue 'impurities'; card '1) Removal of impurities' (52) on cue 'removal'.","tts_text":"الـ steel محتاج حاجتين: الأول، removal of impurities.","screen_text":"1) Removal of impurities"},{"id":"l5","visual":"Small coloured dots (dark C, plus two others unlabeled) drop into the ladle on cue 'addition'; card '2) Addition of some elements' (52) on cue 'elements'; tag 'required properties' (44) on cue 'properties'.","tts_text":"والتاني، addition of elements معينة، عشان الـ properties المطلوبة.","screen_text":"2) Addition of some elements"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): the ladle with a small coral pill 'Steel = pure iron?' on cue 'نقي' + YK.wrongMark on cue 'لأ'; on 'لأ' the coral pill goes and 'Elements added ✓' enters bigger (verifier nice-to-have) and holds into l7; ONE YK.rightMark on cue 'carbon'. A dark 'C' atomDisc drops in with tag 'e.g. carbon' (44) on cue 'carbon'.","tts_text":"الـ steel iron نقي؟ لأ، بنضيف له carbon مثلًا.","screen_text":"Steel = pure iron? ✕  Elements added ✓"},{"id":"l7","visual":"Book list p.18, one name per line (names only; internals are not in the book, so no cutaways): title 'Steel furnaces' (56) on cue 'أفران'; furnace 1, a plain labelled silhouette '1. The oxygen converters' at y 760, enters on cue 'converters'. All three names stay on screen to the end of l9 (a one-name-per-line list). Keep every drawing inside x 108-972.","tts_text":"وبيتعمل في تلات أفران: أولها الـ oxygen converters.","screen_text":"Steel furnaces: 1. The oxygen converters"},{"id":"l8","visual":"Furnace 2 '2. Open-hearth furnace' at y 1060 enters on cue 'open' (not 'open-hearth': hyphenated needles miss); its base plate stays inside x >= 108 (verifier nice-to-have).","tts_text":"تانيها الـ open-hearth furnace.","screen_text":"2. Open-hearth furnace"},{"id":"l9","visual":"Furnace 3 '3. Electric furnace' at y 1360 enters on cue 'electric'; the three-name list holds to line end.","tts_text":"وتالتها الـ electric furnace.","screen_text":"3. Electric furnace"},{"id":"l10","style":"curious","visual":"New-case check (lesson asked 'impurities removed, nothing added'; episode asked 'furnace iron still holds sulphur'). The ladle (y 1000) with a violet Mn atomDisc hovering above on cue 'manganese'; two YK.choice chips stacked (x 540, y 1250 / 1360) '1) Removal of impurities' / '2) Addition of some elements' (≤ 864 px at 56: check the still; fall back to '1) Removal' / '2) Addition'); YK.band 'Adding Mn: which process?'. YK.thinkRing(ctx, t, 540, 1550, {start: YK.cueEnd('l10'), end: YK.cue('l11')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l11').","tts_text":"مصنع بيضيف manganese للـ iron… دي أنهي عملية؟","screen_text":"Adding manganese to iron: which process?","pause_after_s":2},{"id":"l11","visual":"Answer: chip 2 glows mint and the Mn disc drops in on cue 'addition'; chip 1 dims; ONE YK.rightMark.","tts_text":"دي الـ addition of elements، عشان الـ properties المطلوبة.","screen_text":"Addition of some elements ✓"},{"id":"l12","visual":"Voiced lock-in: YK.takeaway({title:'Iron production and steel', line:'Steel: remove impurities, add elements', t, pulse:[{word:'remove', at:YK.cue('l12','تتشال')}, {word:'add', at:YK.cue('l12','تتضاف')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ steel: impurities تتشال، و elements تتضاف.","screen_text":"Steel: remove impurities, add elements","pause_after_s":1.5}],"logline":"After reduction comes iron production: types of iron such as cast iron and steel. Steel making rests on two processes, removal of impurities from the furnace iron and addition of some elements (e.g. carbon), in oxygen converters, the open-hearth furnace or the electric furnace (book 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colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: a custom circuit, YK.icon 'battery' (200, x 300, y 1050) and YK.icon 'lamp' (200, x 780, y 1050) joined by two wire paths (stroke 10, C.steel) above and below; the lamp glows (YK.glowCircle) and small gold YK.dot charges stream round the loop from frame 0; YK.band 'Cut one wire. !{Why dark}?' (104) at 0. A snip gap opens in the top wire on cue 'نقطع': the dots stop and the glow dies on the same cue.","tts_text":"ليه اللمبة بتطفي لما نقطع سلك واحد بس؟","screen_text":"Cut one wire. Why dark?"},{"id":"l2","visual":"The gap closes again; dots flow; YK.termCard({term:'Electric current', def:'A flow of electric charges through a wire or a solution', keys:['flow','charges']}) (y 1500) on cue 'electric'; the dots pulse gold on cue 'charges'. Prereq chip 'Electric charges attract and repel' at line start (after the first 2 s). New term 1.","tts_text":"الـ electric current يعني charges بتتحرك، في سلك أو solution كمان.","screen_text":"Electric current: a flow of electric charges"},{"id":"l3","visual":"Card exits. A gold push chevron at the battery on cue 'بتزق'; the whole loop is traced gold end to end with label 'closed path' (48, y 1300) on cue 'path'; a dashed gap flickers open/closed on cue 'قطع' to show what breaks it. New term 2.","tts_text":"الـ battery بتزق الـ charges، بس لازم closed path من غير قطع.","screen_text":"The battery pushes · a closed path"},{"id":"l4","visual":"YK.camera push (0.8 s) into the bottom wire: a row of grey metal atomDiscs (r 40, symbol:false) with cyan YK.dot electrons drifting left → right between them on cue 'electrons'; label 'free electrons' (48) on cue 'free'.","tts_text":"في السلك، الـ free electrons هي اللي بتتحرك.","screen_text":"Wire: free electrons move"},{"id":"l5","visual":"Cut to YK.beaker(ctx, 540, 1150, 560, 560, {level:0.75, color:'rgba(200,210,230,0.25)'}) with two custom plates (roundRect 40 × 360): left '+' (coral), right '−' (cyan), wired to a small battery icon above (y 760); YK.dot ions with sign '+' drift to the − plate and sign '−' dots to the + plate on cue 'بتتحرك'; label 'ions' (48) on cue 'ions'; tag 'opposite plate' (44) on cue 'العكسي'. Prereq: ions are met earlier in the path (no chip: not a map prereq here).","tts_text":"وفي الـ solution، الـ ions بتتحرك، كل ion للـ plate العكسي.","screen_text":"Solution: ions move to the opposite plate"},{"id":"l6","visual":"Myth (the lesson hook's wrong option 'it stays lit: the battery still has energy'; no misconception recorded for this concept): Back to the circuit with the top wire cut; the battery glows 'full' and a coral pill 'battery alone?' sits by it. Small coral pill on cue 'كفاية' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'current' and stays longer on screen. The cut gap flashes coral on cue 'مقطوع' (dots frozen); then the wire closes, the dots run and the lamp lights with tag 'closed path ✓' (52, mint) on cue 'current'.","tts_text":"ناس فاكرة إن الـ battery كفاية… لأ، لو الـ path مقطوع، الـ current بيقف.","screen_text":"Battery alone is enough? ✕  A closed path ✓"},{"id":"l7","style":"curious","visual":"New-case check (the lesson used a copper wire, solid salt, salt solution and sugar water; the episode used ions in solutions). The top wire is cut again; a grey nail (custom rect + head, label 'iron nail', 44) drops across the gap on cue 'بمسمار'; the lamp sits dark with a '?' (mono 72) on cue 'هتنوّر'; YK.band 'Iron nail in the gap: lamp on?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب لو قفلنا الفتحة بمسمار iron… اللمبة هتنوّر؟","screen_text":"Gap closed with an iron nail: lamp on?","pause_after_s":2},{"id":"l8","visual":"Answer: cyan electron dots stream through the nail on cue 'electrons'; the loop traces gold and the lamp lights on cue 'اتقفل'; ONE YK.rightMark on cue 'أيوه'.","tts_text":"أيوه، الـ iron فيه free electrons، فالـ path اتقفل.","screen_text":"Yes: free electrons close the path ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Electric current', line:'Moving charges + a closed path', t, pulse:[{word:'charges', at:YK.cue('l9','charges')}, {word:'path', at:YK.cue('l9','path')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"محتاج charges بتتحرك، و closed path كمان.","screen_text":"Moving charges + a closed path","pause_after_s":1.5}],"logline":"An electric current is a flow of electric charges, pushed by a source such as a battery round a closed path: free electrons move in a wire, ions move to the oppositely charged plate in a solution (background for electro-deposition, book 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كمان","countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":5},{"id":"chem-s3-en.video-short-chem.electroplating-basic","kind":"short","version":1,"ord":410,"content_lang":"ar-EG","primary_concept_id":"chem.electroplating-basic","concepts":[{"concept_id":"chem.electroplating-basic","role":"primary"}],"title":"Electroplating","payload":{"title":"Electroplating","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: YK.beaker(ctx, 540, 1150, 560, 600, {level:0.75, color:'rgba(200,210,230,0.25)'}) with a grey iron key (custom, label 'Fe key', 44) hanging into it from a rod; a small battery icon above (y 700) wired to the key and to a plate; the key's surface tints copper-coloured (metal colour) from 0 to 1 over the first 2 s and loops; YK.band 'Iron key. !{Copper} coat. How?' (100) at 0. Key glints on cue 'copper'.","tts_text":"مفتاح iron نزل في محلول… وطلع متغطي copper! إزاي؟","screen_text":"Iron key. Copper coat. How?"},{"id":"l2","visual":"YK.termCard({term:'Electroplating', def:'Coating an object with a thin metal layer by passing a current through a solution of that metal\\'s ions', keys:['current','ions']}) (y 1500) on cue 'electroplating'; current arrows run along the wires on cue 'current'; '+' ion dots appear in the liquid on cue 'ions'. Prereq chip 'Electric current' at line start (after the first 2 s). New term 1.","tts_text":"الـ electroplating: نعدّي current في solution فيه metal ions، فيتغطى الجسم.","screen_text":"Electroplating: current through metal ions"},{"id":"l3","visual":"Card exits. The key's wire glows cyan with a '−' badge (52) on cue 'negative'; YK.dot ions with sign '+' and label 'Cu^2+' (YK.label, 44, on one ion) drift to the key on cue 'بتتشد'. Prereq chip 'Ions (cations and anions)' at line start.","tts_text":"المفتاح على الـ negative terminal، فالـ copper ions الموجبة بتتشد له.","screen_text":"Object on the negative terminal: Cu²⁺ attracted"},{"id":"l4","visual":"YK.camera push onto the key surface: one '+' ion meets two cyan electron dots on cue 'electrons' and becomes a copper atomDisc 'Cu' sitting on the surface on cue 'ويترسب'; the copper layer thickens; the short's ONE written equation 'Cu^2+ + 2e^- -> Cu' (mono 60, y 760) on cue 'بياخد'.","tts_text":"كل copper ion بياخد اتنين electrons، ويترسب copper عليه.","screen_text":"Cu²⁺ + 2e⁻ → Cu"},{"id":"l5","visual":"Aha hold >= 1.5 s: label 'Cathode (−)' (56, gold) on the key on cue 'cathode'; tag 'reduction: gain of electrons' (44) on cue 'reduction' (reduction is a prerequisite word: redox by electrons). New term 2.","tts_text":"المفتاح هنا الـ cathode، والـ reduction بيحصل عنده.","screen_text":"Cathode: where reduction happens"},{"id":"l6","visual":"Myth (the lesson's 'common mistake': the object goes on the positive terminal; no misconception recorded): A ghost key wired to a coral '+' badge. Small coral pill on cue 'positive' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'بيزق' and stays longer on screen. On the ghost, the '+' ions bounce away from the key (arrows pointing outward) on cue 'بيزق', then the real key on '−' returns with tag 'object on − ✓' (52).","tts_text":"ناس فاكرة إنه يتوصل بالـ positive… لأ، ده بيزق الـ ions بعيد.","screen_text":"Object on +? ✕  On − ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: key/copper, nickel/zinc ions, spoon/silver; episode: copper + tin ions). A grey tap (custom, label 'steel tap', 44) on the '−' wire in the beaker on cue 'حنفية'; '+' dots with one label 'chromium ions' (44) on cue 'chromium' (no charge written: the bath's ion is not in the book); a '?' over the tap surface on cue 'coat'; YK.band 'Steel tap, chromium ions: coat of?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"حنفية steel على الـ negative، في chromium ions… الـ coat من إيه؟","screen_text":"Steel tap on −, in chromium ions: coat of?","pause_after_s":2},{"id":"l8","visual":"Answer: the Cr ions land on the tap and a silver-grey chromium layer grows on cue 'بتترسب'; label 'Cr coat' (48) on cue 'chromium'; ONE YK.rightMark.","tts_text":"من الـ chromium، لأن الـ ions بتاعته هي اللي بتترسب.","screen_text":"Chromium: the coat comes from the ions ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Electroplating', line:'Object = cathode: metal ions coat it', formula:'Cu^2+ + 2e^- -> Cu', t, pulse:[{word:'cathode', at:YK.cue('l9','cathode')}, {word:'ions', at:YK.cue('l9','ions')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الجسم هو الـ cathode، والـ metal ions بتغطيه.","screen_text":"Object = cathode: metal ions coat it","pause_after_s":1.5}],"logline":"Electroplating passes a current through a solution of metal ions: the object, joined to the negative terminal, is the cathode, where the metal ions gain electrons (reduction) and coat it with that metal (background for electro-deposition of alloys, book p.19; taught fully in 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iron نزل في محلول وطلع متغطي copper\nإزاي\nالـ electroplating نعدّي current في\nsolution فيه metal ions فيتغطى الجسم\nالمفتاح على الـ negative terminal فالـ\ncopper ions الموجبة بتتشد له\nكل copper ion بياخد اتنين electrons ويترسب\ncopper عليه\nالمفتاح هنا الـ cathode والـ reduction\nبيحصل عنده\nناس فاكرة إنه يتوصل بالـ positive لأ ده\nبيزق الـ ions بعيد\nحنفية steel على الـ negative في chromium\nions الـ coat من إيه\nمن الـ chromium لأن الـ ions بتاعته هي\nاللي بتترسب\nالجسم هو الـ cathode والـ metal ions\nبتغطيه","countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":6},{"id":"chem-s3-en.video-short-alloy.definition-preparation","kind":"short","version":1,"ord":412,"content_lang":"ar-EG","primary_concept_id":"alloy.definition-preparation","concepts":[{"concept_id":"alloy.definition-preparation","role":"primary"}],"title":"Alloys: definition and preparation","payload":{"title":"Alloys: definition and preparation","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: a steel beam (custom, steel grey) with a zoom bubble showing grey Fe discs and a few small dark 'C' discs (YK.atomDisc r 26) jiggling in place from frame 0; YK.band 'Steel has carbon. Still an !{alloy}?' (96) at 0. The C discs glow on cue 'carbon'; tag 'non-metal?' (44, coral) on cue 'metal'.","tts_text":"الـ steel فيه carbon… والـ carbon مش metal! يبقى alloy إزاي؟","screen_text":"Steel has carbon. Still an alloy?"},{"id":"l2","visual":"Beam exits; two metal ingots (custom, grey Fe and silver-grey Mn, labelled 'Fe' / 'Mn', 52) slide together into one block on cue 'metals'; label 'Alloy' (64, gold) on cue 'alloy'; tag 'two metals or more' (48) on cue 'أكتر'. Prereq chip 'Properties of metals and non-metals' at line start (after the first 2 s). New term 1.","tts_text":"الـ alloy غالبًا اتنين metals أو أكتر مع بعض.","screen_text":"Alloy: usually two metals or more"},{"id":"l3","visual":"Myth (concept misconception 1 (TOP)): A coral rule card 'alloys = metals only'. Small coral pill on cue 'بس' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'non-metal' and stays longer on screen. The steel zoom bubble returns bigger: Fe + C with tag 'metal + non-metal' (52, mint) on cue 'non-metal' and label 'Steel (Fe + C)' (48) on cue 'steel'.","tts_text":"ناس فاكرة إنه metals بس… لأ، ممكن metal مع non-metal، زي الـ steel كده.","screen_text":"Metals only? ✕  Metal + non-metal (steel) ✓"},{"id":"l4","visual":"Step rail at y 700 (two chips, Cairo 800 44: 'By melting' · 'By electro-deposition'); chip 1 lights gold on cue 'melting'; two solid ingots melt into one glowing orange liquid in a crucible (custom, y 1100) on cue 'ندوّب'; the liquid cools slowly to a solid grey block (colour tween 2 s) on cue 'يبردوا'. Prereq chip 'States of matter, melting and boiling points' at line start.","tts_text":"الأولى: melting، ندوّب الـ metals سوا، ونسيبهم يبردوا بالراحة.","screen_text":"1) By melting: melt together, cool gradually"},{"id":"l5","visual":"Chip 2 lights gold on cue 'electro-deposition'; YK.beaker (540, 1150, 520, 520, pale) with an object on the '−' wire; two kinds of neutral '+' identity dots lettered 'Cu' and 'Zn' (no ion colours, mono 40 inside the dot) land on it together on cue 'يترسبوا'; tag 'at the same time' (48) on cue 'الوقت'. Prereq chip 'Electroplating' at line start. New term 2.","tts_text":"التانية: electro-deposition، اتنين metals يترسبوا في نفس الوقت.","screen_text":"2) By electro-deposition: two metals at the same time"},{"id":"l6","visual":"Book example (p.19): the object becomes an iron handle (custom, label 'iron handle', 44) on cue 'iron'; a gold-brown Cu + Zn layer grows over it on cue 'سوا'; label 'Cu + Zn' (mono 52) on cue 'zinc'.","tts_text":"زي يد iron، يترسب عليها copper و zinc سوا.","screen_text":"Iron handles: Cu + Zn deposit together"},{"id":"l7","style":"curious","visual":"New-case check (lesson: copper ions only / zinc melted alone; episode: pure gold, copper + tin ions, nickel + chromium ions). Same beaker; only zinc '+' dots (one label 'Zn^2+') on cue 'zinc'; a key on the '−' wire gets a grey coat on cue 'مفتاح'; YK.band 'Zinc ions only: an alloy?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب solution فيه zinc ions بس، وغطّينا بيه مفتاح… الـ coat ده alloy؟","screen_text":"Zinc ions only, on a key: is the coat an alloy?","pause_after_s":2},{"id":"l8","visual":"Answer: the coat gets label 'Zn only' (48) on cue 'metal'; tag 'two or more needed' (48) on cue 'أكتر'; ONE YK.rightMark on cue 'لأ'.","tts_text":"لأ، metal واحد مش alloy؛ لازم اتنين أو أكتر.","screen_text":"No: one metal is not an alloy ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Alloys: definition and preparation', line:'Melting or electro-deposition; may include a non-metal', t, pulse:[{word:'Melting', at:YK.cue('l9','melting')}, {word:'electro-deposition', at:YK.cue('l9','electro-deposition')}, {word:'non-metal', at:YK.cue('l9','non-metal')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"بالـ melting أو الـ electro-deposition، والـ non-metal مسموح.","screen_text":"Melting or electro-deposition; may include a non-metal","pause_after_s":1.5}],"logline":"An alloy is usually made of two metals or more (ferrochromium, ferromanganese…) but may be a metal with a non-metal such as carbon (steel); alloys are prepared by melting the metals together and leaving them to cool gradually, or by electro-deposition of two metals or more at the same time (brass on iron handles from copper and zinc ions), book 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steel فيه carbon والـ carbon مش metal\nيبقى alloy إزاي\nالـ alloy غالبًا اتنين metals أو أكتر مع\nبعض\nناس فاكرة إنه metals بس لأ ممكن metal مع\nnon-metal زي الـ steel كده\nالأولى melting ندوّب الـ metals سوا\nونسيبهم يبردوا بالراحة\nالتانية electro-deposition اتنين metals\nيترسبوا في نفس الوقت\nزي يد iron يترسب عليها copper و zinc سوا\nطب solution فيه zinc ions بس وغطّينا بيه\nمفتاح الـ coat ده alloy\nلأ metal واحد مش alloy لازم اتنين أو أكتر\nبالـ melting أو الـ electro-deposition\nوالـ non-metal مسموح","countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":7},{"id":"chem-s3-en.video-short-alloy.interstitial","kind":"short","version":1,"ord":414,"content_lang":"ar-EG","primary_concept_id":"alloy.interstitial","concepts":[{"concept_id":"alloy.interstitial","role":"primary"}],"title":"Interstitial alloys","payload":{"title":"Interstitial alloys","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: two bars side by side (x 320 'Pure iron' / x 760 'Steel', labels 48) and a YK.hammer striking them alternately from frame 0: the pure-iron bar dents, the steel bar does not; YK.band 'Pure iron soft. Steel hard. !{Why}?' (96) at 0. The steel bar glints on cue 'أجمد'.","tts_text":"الـ pure iron طري… ونضيف شوية carbon يبقى أجمد! إزاي؟","screen_text":"Pure iron soft. Steel hard. Why?"},{"id":"l2","visual":"Zoom into the pure-iron bar: YK.lattice(ctx, 160, 760, 760, 560, {rows:5, cols:8, pack:'hex'}) reveals row by row on cue 'مترصوصة'; label 'crystal lattice' (52) on cue 'lattice'. Prereq chip 'Metallic bond' at line start (after the first 2 s). New term 1. Book fig 1-5 a.","tts_text":"الـ atoms جوه الـ metal مترصوصة في crystal lattice منظم.","screen_text":"Crystal lattice: atoms in compact close rows"},{"id":"l3","visual":"YK.hammer(ctx, 860, 720, {p: YK.prog(t, YK.cue('l3','بالشاكوش'), YK.cue('l3','بالشاكوش') + 0.4)}) drives lattice slip 0 → 1 (top rows slide one spacing right, slip plane drawn) on cue 'تزحلق'; tag 'layer slips' (48) on cue 'layer'. Book fig 1-5 b.","tts_text":"لو ضربناه بالشاكوش، الـ layer تزحلق فوق التانية.","screen_text":"Hammering: a layer slips over the others"},{"id":"l4","visual":"Slip resets; small gold atoms enter the gaps one by one (lattice insert:[…], scale 0.45) on cue 'صغيرة'; YK.termCard({term:'Interstitial alloy', def:'Atoms of an element with a small atomic size enter the spaces of the crystal lattice of a pure metal', keys:['small atomic size','spaces']}) (y 1500) on cue 'interstitial'; the gaps pulse on cue 'spaces'. New term 2. Book fig 1-5 c.","tts_text":"في الـ interstitial alloy، فيه atoms صغيرة بتدخل الـ spaces دي.","screen_text":"Interstitial alloy: small atoms in the spaces"},{"id":"l5","visual":"Aha hold >= 1.5 s: the hammer strikes again; lattice {blocked:true} so the top rows start to slide and spring back on cue 'بتمنع'; tag 'harder' (56, gold) on cue 'أجمد'.","tts_text":"الـ atoms دي بتمنع الـ layers تزحلق، فالـ metal يبقى أجمد.","screen_text":"Small atoms block the slip: harder"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A ghost lattice where one grey Fe disc is swapped for a small C disc (substitute:[…]) with pill 'replaces Fe?'. Small coral pill on cue 'مكان' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'spaces' and stays longer on screen. The ghost exits; the real lattice returns with every grey Fe disc in place and the small C discs glowing in the gaps, tag 'in the spaces ✓' (52) on cue 'spaces'.","tts_text":"ناس فاكرة إن الـ carbon بياخد مكان الـ iron… لأ، الـ spaces هي مكانه.","screen_text":"C replaces Fe atoms? ✕  C sits in the spaces ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: metal M + small Z atoms, steel vs cementite; episode: carbon or nickel in iron's spaces). Plain iron lattice; small blue inserted discs (lattice insert, scale 0.45) slip into the gaps on cue 'nitrogen', with one label 'N atoms' (48) (the lattice draws no symbols); the hammer hangs above, still; YK.band 'Small N atoms in iron: harder or softer?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب nitrogen atoms صغيرة دخلت spaces الـ iron… أجمد ولا أطرى؟","screen_text":"Small N atoms enter iron's spaces: harder or softer?","pause_after_s":2},{"id":"l8","visual":"Answer: the hammer strikes; blocked slip springs back on cue 'اتقفلت'; tag 'harder' (52, mint) on cue 'أجمد'; ONE YK.rightMark.","tts_text":"أجمد، لأن الـ layers اتقفلت ومبقتش تزحلق.","screen_text":"Harder: the layers are blocked ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Interstitial alloys', line:'Small atoms in the spaces: a harder metal', t, pulse:[{word:'spaces', at:YK.cue('l9','spaces')}, {word:'harder', at:YK.cue('l9','أجمد')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"في الـ spaces atoms صغيرة، فالـ metal أجمد.","screen_text":"Small atoms in the spaces: a harder metal","pause_after_s":1.5}],"logline":"In a pure metal the atoms sit in compact close rows and a layer slips on hammering; in an interstitial alloy, atoms of an element with a small atomic size enter the spaces of the crystal lattice and block the slipping, so the metal gets harder and other physical properties change (steel = iron + carbon), book p.19, fig 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pure iron طري ونضيف شوية carbon يبقى\nأجمد إزاي\nالـ atoms جوه الـ metal مترصوصة في crystal\nlattice منظم\nلو ضربناه بالشاكوش الـ layer تزحلق فوق\nالتانية\nفي الـ interstitial alloy فيه atoms صغيرة\nبتدخل الـ spaces دي\nالـ atoms دي بتمنع الـ layers تزحلق فالـ\nmetal يبقى أجمد\nناس فاكرة إن الـ carbon بياخد مكان الـ\niron لأ الـ spaces هي مكانه\nطب nitrogen atoms صغيرة دخلت spaces الـ\niron أجمد ولا أطرى\nأجمد لأن الـ layers اتقفلت ومبقتش تزحلق\nفي الـ spaces atoms صغيرة فالـ metal أجمد","countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":8},{"id":"chem-s3-en.video-short-alloy.substitutional","kind":"short","version":1,"ord":416,"content_lang":"ar-EG","primary_concept_id":"alloy.substitutional","concepts":[{"concept_id":"alloy.substitutional","role":"primary"}],"title":"Substitutional alloys","payload":{"title":"Substitutional 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colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: an iron lattice (YK.lattice 160, 760, 760, 560, rows 5, cols 8, pack 'hex') with one pink 'Cr' disc hovering above it and dipping toward different spots (a gap? a site?) on a loop from frame 0; YK.band 'Cr in stainless steel: !{where}?' (100) at 0. The Cr disc glows on cue 'chromium'.","tts_text":"الـ chromium جوه الـ stainless steel… قاعد فين بالظبط؟","screen_text":"Cr in stainless steel: where?"},{"id":"l2","visual":"Two Fe discs lift out of the lattice on cue 'بيطلعوا' and pink Cr discs drop into the same sites (lattice substitute:[…], scale 1) on cue 'مكانهم'; YK.termCard({term:'Substitutional alloy', def:'Some atoms of the pure metal are replaced by atoms of another metal', keys:['replaced']}) (y 1500) on cue 'substitutional'. Book example: ferrochrome (stainless steel). New term 1.","tts_text":"ده substitutional alloy: بعض الـ iron atoms بيطلعوا، والـ chromium بياخد مكانهم.","screen_text":"Substitutional alloy: Cr replaces some Fe atoms"},{"id":"l3","visual":"Card exits. The lattice moves up (y 600–1080); full-width checklist card (x 108–972, y 1180–1600, rows Cairo 800 48; a 352 px card would cut 'Same crystal lattice'): row 'Same atomic radius' ticks in on cue 'radius' (a Cr disc and an Fe disc overlap at equal size beside it); row 'Same crystal lattice' on cue 'lattice'.","tts_text":"الشرط: نفس الـ atomic radius، ونفس الـ crystal lattice كمان.","screen_text":"Condition: same atomic radius, same crystal lattice"},{"id":"l4","visual":"Row 'Same chemical properties' ticks in on cue 'properties'; the three rows glow together (book p.20: all three).","tts_text":"ونفس الـ chemical properties، وإلا مش هيقعد مكانه.","screen_text":"…and the same chemical properties"},{"id":"l5","visual":"YK.chart bars Cr 1.17, Mn 1.17, Fe 1.16, Co 1.16, Ni 1.15, Cu 1.17 (book table p.12; Sc/Ti/V kept back for the check) grow on cue 'chromium' → cue 'copper', flat gold line + label 'nearly constant' (48) on cue 'ثابت'; footnote 'Book table p.12' (40, 60%). Prereq chip 'Atomic radius: nearly constant' at line start.","tts_text":"ومن الـ chromium للـ copper الـ radius شبه ثابت، فبيعملوا alloys بسهولة.","screen_text":"Cr → Cu: radius nearly constant"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A coral card 'any two metals' with two mismatched discs (no sizes or values). Small coral pill on cue 'ينفعوا' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'شروط' and stays longer on screen. The three-row checklist returns bigger with all rows lit on cue 'شروط'.","tts_text":"ناس فاكرة إن أي اتنين metals ينفعوا… لأ، لازم التلات شروط.","screen_text":"Any two metals? ✕  All three conditions ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: Cu/Ni, 'which is not a condition'; episode: cobalt, chromium + iron). Two atomDiscs drawn to the book's radii scale (k = one value for both): 'Sc' 1.44 (label mono 48) on cue 'scandium'; the 'Fe' disc 1.16 on cue 'iron' (book table p.12); the checklist row 'Same atomic radius' shows '?' on cue 'radius'; YK.band 'Sc 1.44, Fe 1.16: substitutional?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب الـ scandium مع الـ iron، بصوا على الـ radius… ينفعوا substitutional سوا؟","screen_text":"Sc (1.44) with Fe (1.16): substitutional?","pause_after_s":2},{"id":"l8","visual":"Answer: the Sc disc tries an Fe site and overflows its neighbours (coral outline) on cue 'مختلف'; row 1 gets a coral ✕ on cue 'وقع'; ONE YK.rightMark by the answer tag 'No: radius differs' (48) on cue 'لأ'.","tts_text":"لأ، الـ radius مختلف، فالشرط الأول وقع.","screen_text":"No: the radius differs ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Substitutional alloys', line:'Radius, lattice and properties must match', t, pulse:[{word:'Radius', at:YK.cue('l9','radius')}, {word:'lattice', at:YK.cue('l9','lattice')}, {word:'properties', at:YK.cue('l9','properties')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ radius والـ lattice والـ properties لازم يتطابقوا.","screen_text":"Radius, lattice and properties must match","pause_after_s":1.5}],"logline":"In a substitutional alloy, some atoms of the pure metal are replaced by atoms of another metal with the same atomic radius, crystal lattice and chemical properties (ferrochrome in stainless steel, copper-gold, ferronickel); the nearly constant atomic radius from Cr to Cu explains their use in alloys (book pp.12-13, 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alloys","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: two lattices side by side (x 320 'Steel', x 760 'Cementite', labels 48): steel with small C discs in the gaps; cementite with Fe and C in an ordered repeating pattern (lattice compound:{ratio:[3,1]} without the formula tag yet); both gently pulsing from frame 0; YK.band 'Same Fe + C. !{Different} types?' (96) at 0. The cementite lattice glows on cue 'cementite'.","tts_text":"الاتنين iron و carbon… بس الـ cementite نوع تاني! ليه؟","screen_text":"Same Fe + C. Different types?"},{"id":"l2","visual":"Steel exits; the cementite lattice moves to the centre; custom bond lines (from the lattice's returned pos()) link each C to its Fe neighbours on cue 'بتتحد'; YK.termCard({term:'Intermetallic alloy', def:'The elements of the alloy combine with each other chemically to form a chemical compound', keys:['combine','chemically']}) (y 1500) on cue 'intermetallic'. New term 1.","tts_text":"في الـ intermetallic alloy، العناصر بتتحد كيميائيًا وتعمل chemical compound جديد.","screen_text":"Intermetallic alloy: elements combine chemically"},{"id":"l3","visual":"Card exits; the lattice tag 'Fe_3C' (mono 72, gold) on cue 'formula'; one repeating unit (3 Fe + 1 C) is outlined on cue 'تلاتة'. Prereq chip 'Interstitial alloys' at line start (steel, the other Fe + C alloy). New term 2.","tts_text":"زي الـ cementite: ليه formula ثابتة، iron تلاتة و carbon واحد.","screen_text":"Cementite: Fe₃C, a fixed formula"},{"id":"l4","visual":"Two swap cards (mono 52, y 1000/1150), no reaction arrow (the short's only written formula row is Fe_3C): 'Fe (2), C (4): Fe_2C' and 'Fe (3), C (4): Fe_4C_3', each ending in a coral '≠ Fe_3C' on cue 'valency'; tag 'disobeys the valence law' (48) on cue 'law'. The swap is used only for metal + non-metal (Fe with C). Prereq chip 'Valency and writing chemical formulas' at line start.","tts_text":"والـ formula بتكسر الـ valence law: مفيش valency للـ iron تدّيها.","screen_text":"Fe₃C disobeys the valence law"},{"id":"l5","visual":"Two group columns only (custom, labels 'IIIA' / 'IB', 48, book Roman notation): 'Al' sits in IIIA and 'Cu' in IB, joined by a bracket 'Duralumin (Al-Cu)' (48) on cue 'duralumin'; the two columns glow apart on cue 'groups'. Book p.20. New term 3.","tts_text":"ومعادنه من groups مختلفة، زي الـ duralumin كده.","screen_text":"Different groups: duralumin (Al-Cu)"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A coral ghost of loose Fe and C discs tumbling in a jar with pill 'mixture?'. Small coral pill on cue 'mixture' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'compound' and stays longer on screen. The ordered Fe_3C lattice returns bigger with bond lines lit on cue 'متحدة'.","tts_text":"ناس فاكرة إنه physical mixture… لأ، ده compound، والعناصر متحدة.","screen_text":"Physical mixture? ✕  Chemical compound ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: X3C with valency 2, P3Q; episode: M2C). Gold 'Au' and grey 'Pb' discs (r 56) on cues 'gold' / 'lead'; tag 'Au_2Pb' (mono 64) on cue 'formula'; two pills 'compound' / 'mixture' (48) on cue 'compound'; YK.band 'Au_2Pb: compound or mixture?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب الـ gold مع الـ lead بيدّوا formula ثابتة… compound ولا mixture بس؟","screen_text":"Au₂Pb, a fixed formula: compound or mixture?","pause_after_s":2},{"id":"l8","visual":"Answer: the Au and Pb discs lock into a 2 : 1 bonded unit on cue 'متحدة'; pill 'compound' turns mint on cue 'compound'; ONE YK.rightMark.","tts_text":"ده compound، لأن الـ formula ثابتة والعناصر متحدة.","screen_text":"Compound: a fixed formula ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Intermetallic alloys', line:'A compound that disobeys the valence law', formula:'Fe_3C · Au_2Pb', t, pulse:[{word:'compound', at:YK.cue('l9','compound')}, {word:'valence', at:YK.cue('l9','valence')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"ده compound، والـ valence law مش ماشي عليه.","screen_text":"A compound that disobeys the valence law","pause_after_s":1.5}],"logline":"In an intermetallic alloy the elements combine chemically to form a chemical compound whose formula disobeys the valence law (cementite Fe₃C: no valency of iron gives it); its metals are not from the same group (duralumin Al-Ni, Al-Cu; lead-gold Au₂Pb), book 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iron و carbon بس الـ cementite نوع\nتاني ليه\nفي الـ intermetallic alloy العناصر بتتحد\nكيميائيًا وتعمل chemical compound جديد\nزي الـ cementite ليه formula ثابتة iron\nتلاتة و carbon واحد\nوالـ formula بتكسر الـ valence law مفيش\nvalency للـ iron تدّيها\nومعادنه من groups مختلفة زي الـ duralumin\nكده\nناس فاكرة إنه physical mixture لأ ده\ncompound والعناصر متحدة\nطب الـ gold مع الـ lead بيدّوا formula\nثابتة compound ولا mixture بس\nده compound لأن الـ formula ثابتة والعناصر\nمتحدة\nده compound والـ valence law مش ماشي عليه","countable":true,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":10},{"id":"chem-s3-en.video-short-fe.physical-properties","kind":"short","version":1,"ord":444,"content_lang":"ar-EG","primary_concept_id":"fe.physical-properties","concepts":[{"concept_id":"fe.physical-properties","role":"primary"}],"title":"Physical properties of iron","payload":{"title":"Physical properties of iron","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: YK.icon 'bridge' (220, x 320, y 900) and a car outline (custom, x 760) already drawn, both tinted steel grey; a shiny bar labelled 'Pure iron' (48) at y 1350 with a coral '?' (mono 72) beside it, swinging gently from frame 0; YK.band 'Pure iron: !{no} industrial importance?' (88) at 0. The bar pulses on cue 'pure'.","tts_text":"الكباري والعربيات مليانة iron… بس الـ pure iron مالوش industrial importance! ليه؟","screen_text":"Pure iron: no industrial importance?"},{"id":"l2","visual":"Icons exit; a YK.hammer strikes the bar and leaves a deep dent on cue 'soft'; a small gauge 'hardness' (custom, needle low, no numbers) on cue 'hardness'. Book p.20.","tts_text":"لأنه relatively soft: الـ hardness بتاعته قليلة.","screen_text":"Relatively soft, low hardness"},{"id":"l3","visual":"Three quick tiles top → bottom (y 760 / 1050 / 1340): the bar flattens into a sheet on cue 'malleable'; it draws into a wire on cue 'ductile'; a YK.magnet pulls it on cue 'magnetic'; one label each (48). Prereq chip 'Properties of metals and non-metals' at line start.","tts_text":"وهو malleable و ductile، وكمان magnetic بيتشد للمغناطيس.","screen_text":"Malleable · ductile · magnetic"},{"id":"l4","visual":"Tiles exit; a YK.thermo (beats.js) fills to '1538 °C' (YK.label mono 56) on cue 'وتلاتين'; a 1 cm³ cube with '7.87 g/cm^3' (YK.label mono 56) on cue 'density'. Book values only. Prereq chip 'Density' at line start.","tts_text":"وبيدوب عند ألف خمسمية تمانية وتلاتين، والـ density سبعة فاصل سبعة وتمانين.","screen_text":"Melts at 1538 °C · density 7.87 g/cm³"},{"id":"l5","visual":"Zoom into the bar: a pure lattice (YK.lattice rows 4, cols 7) on cue 'purity'; a few small gold impurity atoms enter the gaps on cue 'impurities' and the label 'properties change' (48) appears on cue 'بتتغير'.","tts_text":"الـ properties دي بتتغير حسب الـ purity ونوع الـ impurities فيه.","screen_text":"Properties depend on purity and impurities"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A coral pill 'very hard?' over the pure lattice. Small coral pill on cue 'جدًا' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'بتزحلق' and stays longer on screen. The pure lattice slips on a hammer hit (slip 0 → 1) on cue 'بتزحلق' with tag 'layers slip easily ✓' (52). Prereq chip 'Interstitial alloys' at line start.","tts_text":"ناس فاكرة إن الـ pure iron جامد جدًا… لأ، الـ layers بتاعته بتزحلق بسهولة.","screen_text":"Very hard? ✕  Layers slip easily ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: 78.7 g density calc, harder factory sample, bridges; episode: a sample melting at 1450 °C). A nail (custom) being hammered into a board, frozen mid-strike, on cue 'مسمار'; two pills 'pure iron' / 'steel' (48) on cue 'pure'; YK.band 'A nail that must not bend: which?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"مسمار لازم ميتنيش: الأحسن pure iron ولا steel هنا؟","screen_text":"A nail that must not bend: pure iron or steel?","pause_after_s":2},{"id":"l8","visual":"Answer: pill 'steel' mint on cue 'steel'; a ghost pure-iron nail bends over (coral) on cue 'طري' while the steel nail goes in straight; ONE YK.rightMark.","tts_text":"الـ steel، لأن الـ pure iron طري.","screen_text":"Steel: pure iron is too soft ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Physical properties of iron', line:'Pure iron is soft: iron alloys are used', t, pulse:[{word:'soft', at:YK.cue('l9','طري')}, {word:'alloys', at:YK.cue('l9','alloys')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ pure iron طري، فبنستخدم الـ alloys بداله.","screen_text":"Pure iron is soft: iron alloys are used","pause_after_s":1.5}],"logline":"Pure iron has no industrial importance: it is relatively soft (low hardness), malleable, ductile and magnetic, melts at 1538 °C and has a density of 7.87 g/cm³; its physical properties depend on its purity and the nature of its impurities, so steels and iron alloys with specific properties are used (book 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colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: a glowing red-hot iron bar (custom, C.molten glow pulsing from frame 0) at y 1050 with faint dry-air arrows (cyan) blowing over it; a small coral 'rust?' pill (44) floating above; YK.band 'Red-hot iron + dry air: !{rust}?' 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Glow flares on cue 'red'.","tts_text":"الـ iron وهو red hot في هوا ناشف… هيصدّي زي العادي؟","screen_text":"Red-hot iron + dry air: rust?"},{"id":"l2","visual":"Molecules, no written equation (the one equation is l4): three grey 'Fe' atomDiscs + two YK.molecule O2 merge into a black cluster labelled 'Fe_3O_4' (YK.label 52) on cue 'magnetic'; a small YK.magnet pulls the black cluster on cue 'أسود'; label 'magnetic iron oxide' (48).","tts_text":"الـ iron وهو red hot، في هوا ناشف، بيدّي magnetic iron oxide أسود.","screen_text":"Dry air → Fe₃O₄, magnetic iron oxide"},{"id":"l3","visual":"Cut to a tube over a burner (custom) with steam wisps entering on cue 'water'; tag '500 °C' (mono 52) on cue 'خمسمية'; the same black 'Fe_3O_4' cluster forms on cue 'oxide'; YK.molecule H2 bubbles leave the tube end on cue 'hydrogen'.","tts_text":"ومع الـ water vapour عند خمسمية درجة، نفس الـ oxide، ومعاه hydrogen كمان.","screen_text":"Water vapour (500 °C) → Fe₃O₄ + H₂"},{"id":"l4","visual":"The short's ONE written equation in two rows (mono 56, x 108-972): '3Fe + 4H_2O' (y 760) / '->[500 °C] Fe_3O_4 + 4H_2' (y 850) on cue 'vapour'; below (y 1150) one YK.molecule H2O hands its red O to an Fe disc on cue 'بيسيب', the H2 drifts off on cue 'يطلع'. Prereq chip 'Oxidation and reduction by oxygen' at line start.","tts_text":"الـ water vapour بيسيب الـ oxygen للـ iron، والـ hydrogen يطلع غاز.","screen_text":"3Fe + 4H₂O →(500 °C) Fe₃O₄ + 4H₂"},{"id":"l5","visual":"Myth (concept misconception 1 (TOP)): A coral ghost red powder 'Fe_2O_3?' (YK.label) over the bar. Small coral pill on cue 'الصدا' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'الحالتين' and stays longer on screen. Two black 'Fe_3O_4' clusters (air | water vapour) side by side, both pulled by the magnet, on cue 'الحالتين'.","tts_text":"ناس فاكرة إنه iron three oxide، زي الصدا… لأ، magnetic iron oxide في الحالتين.","screen_text":"Fe₂O₃, like rust? ✕  Fe₃O₄ in both ✓"},{"id":"l6","style":"curious","visual":"New-case check (lesson: which substance is reduced, air vs vapour statements; episode: iron wool in oxygen + magnet). Six grey Fe discs in two rows on cue 'ستة'; steam wisps on cue 'water'; empty dashed H2 slots with '?' (mono 72) on cue 'hydrogen'; YK.band '6 Fe + water vapour: how many H_2?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l6'), end: YK.cue('l7')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l7').","tts_text":"طب ستة iron مع الـ water vapour… كام جزيء hydrogen يطلع؟","screen_text":"6 Fe atoms + water vapour: how many H₂?","pause_after_s":2},{"id":"l7","visual":"Answer (no second written equation, S3b): the l4 equation returns (mono 56, y 760/850) and gold '×2' tags pop by '3Fe' and by '4H_2' on cue 'اتضاعفت'; eight H2 slots fill with the count tag '8 H_2' (YK.label mono 64) on cue 'تمانية'; ONE YK.rightMark.","tts_text":"تمانية، لأن المعادلة اتضاعفت كلها.","screen_text":"8H₂: the equation doubled ✓"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'Effect of air and water vapour', line:'Both give Fe₃O₄, magnetic iron oxide' (no formula: ~30 glyphs overflow the card), t, pulse:[{word:'Fe₃O₄', at:YK.cue('l8','magnetic')}, {word:'Both', at:YK.cue('l8','الحالتين')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"في الحالتين، الناتج magnetic iron oxide بس.","screen_text":"Both give Fe₃O₄, magnetic iron oxide","pause_after_s":1.5}],"logline":"Red-hot iron with dry air or oxygen gives magnetic iron oxide (3Fe + 2O₂ → Fe₃O₄); red-hot iron at 500 °C with water vapour gives magnetic iron oxide and hydrogen gas (3Fe + 4H₂O → Fe₃O₄ + 4H₂), book p.21: Fe₃O₄, not 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iron وهو red hot في هوا ناشف هيصدّي زي\nالعادي\nالـ iron وهو red hot في هوا ناشف بيدّي\nmagnetic iron oxide أسود\nومع الـ water vapour عند خمسمية درجة نفس\nالـ oxide ومعاه hydrogen كمان\nالـ water vapour بيسيب الـ oxygen للـ iron\nوالـ hydrogen يطلع غاز\nناس فاكرة إنه iron three oxide زي الصدا لأ\nmagnetic iron oxide في الحالتين\nطب ستة iron مع الـ water vapour كام جزيء\nhydrogen يطلع\nتمانية لأن المعادلة اتضاعفت كلها\nفي الحالتين الناتج magnetic iron oxide بس","countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":8},{"id":"chem-s3-en.video-short-fe.reactions-nonmetals","kind":"short","version":1,"ord":448,"content_lang":"ar-EG","primary_concept_id":"fe.reactions-nonmetals","concepts":[{"concept_id":"fe.reactions-nonmetals","role":"primary"}],"title":"Iron with non-metals: chlorine and sulphur","payload":{"title":"Iron with non-metals: chlorine and sulphur","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: one grey 'Fe' atomDisc (r 90, y 1000) between a pale neutral gas cloud (left, custom, label 'Cl_2') and a yellow S powder heap (right, label 'S'), the Fe disc swinging left/right from frame 0; YK.band 'Chlorine vs sulphur:\\nsame !{oxidation state}?' (88, = screen_text) at 0. Cl2 glows on cue 'chlorine', S on cue 'sulphur'.","tts_text":"نسخّن iron مع chlorine، ومرة مع sulphur… نفس الـ oxidation state ولا لأ؟","screen_text":"Chlorine vs sulphur: same oxidation state?"},{"id":"l2","visual":"The short's ONE written equation (mono 60, y 760): '2Fe + 3Cl_2 ->[Δ] 2FeCl_3' on cue 'chloride'; below, an Fe disc with three green Cl discs (each tagged '−1', 40) on cue 'chlorine'; Fe disc charge badge '+3' (gold) on cue 'تلاتة'. Prereq chip 'Oxidation state in compounds' at line start.","tts_text":"الـ chlorine بيدّي iron three chloride، والـ iron فيه موجب تلاتة.","screen_text":"2Fe + 3Cl₂ → 2FeCl₃: iron +3"},{"id":"l3","visual":"Three electron dots leave the Fe disc toward the Cl discs on cue 'بيوصّل'; tag 'strong oxidizing agent' (48) on cue 'oxidizing'.","tts_text":"الـ chlorine ده oxidizing agent قوي، بيوصّل الـ iron لتلاتة.","screen_text":"Chlorine: a strong oxidizing agent"},{"id":"l4","visual":"Atoms only (no second written equation): an Fe disc meets one yellow 'S' disc (tag '−2') on cue 'sulphur'; the pair locks into 'FeS' (YK.label 56) on cue 'sulphide'; Fe badge '+2' on cue 'اتنين'.","tts_text":"لكن مع الـ sulphur، بيدّي iron two sulphide، والـ iron موجب اتنين.","screen_text":"FeS: iron (II) sulphide, +2"},{"id":"l5","visual":"Aha hold >= 1.5 s: a two-step bar (custom: '+2' and '+3' rungs); a chlorine arrow climbs to +3, a sulphur arrow stops at +2 on cue 'بيقف'; tag 'weaker' (48) on cue 'أضعف'.","tts_text":"الـ sulphur أضعف، فالـ iron بيقف عند اتنين.","screen_text":"Sulphur is weaker: iron stops at +2"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A coral ghost 'FeCl_2' (YK.label 56) by the chlorine side. Small coral pill on cue 'chloride' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'تلاتة' and stays longer on screen. 'FeCl_3' returns bigger (mint) on cue 'تلاتة'.","tts_text":"ناس فاكرة إنه iron two chloride مع الـ chlorine… لأ، تلاتة.","screen_text":"FeCl₂? ✕  FeCl₃ ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: AlCl3 balance, states in Fe2O3/FeSO4/FeCO3, Fe + S → FeSO4 error; episode: 4 Fe + Cl2 count, Q1.1). An Fe disc ('+2' badge) paired 1 : 1 with a grey 'X' disc showing '?' on cue 'ذرة'; label 'FeX' (YK.label 56) on cue 'مجهول'; YK.band 'FeX with iron +2: X = ?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب iron وعنصر مجهول، ذرة قصاد ذرة، والـ iron موجب اتنين… العنصر كام؟","screen_text":"Iron + element X → FeX, iron +2: X is…?","pause_after_s":2},{"id":"l8","visual":"Answer: the X disc badge becomes '−2' on cue 'اتنين'; the S disc from l4 slides in beside it on cue 'sulphur'; ONE YK.rightMark.","tts_text":"سالب اتنين، زي الـ sulphur بالظبط.","screen_text":"X is −2, like sulphur ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Iron with non-metals: chlorine and sulphur', line:'Chlorine: FeCl₃ (+3) · sulphur: FeS (+2)', t, pulse:[{word:'Chlorine', at:YK.cue('l9','chlorine')}, {word:'sulphur', at:YK.cue('l9','sulphur')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ chlorine تلاتة، والـ sulphur اتنين.","screen_text":"Chlorine: FeCl₃ (+3) · sulphur: FeS (+2)","pause_after_s":1.5}],"logline":"Heated iron gives iron (III) chloride with chlorine (2Fe + 3Cl₂ → 2FeCl₃, iron +3) but iron (II) sulphide with sulphur (Fe + S → FeS, iron +2): sulphur is a weaker oxidizing agent than chlorine (book p.21; Q1.1 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iron مع chlorine ومرة مع sulphur نفس\nالـ oxidation state ولا لأ\nالـ chlorine بيدّي iron three chloride\nوالـ iron فيه موجب تلاتة\nالـ chlorine ده oxidizing agent قوي بيوصّل\nالـ iron لتلاتة\nلكن مع الـ sulphur بيدّي iron two sulphide\nوالـ iron موجب اتنين\nالـ sulphur أضعف فالـ iron بيقف عند اتنين\nناس فاكرة إنه iron two chloride مع الـ\nchlorine لأ تلاتة\nطب iron وعنصر مجهول ذرة قصاد ذرة والـ iron\nموجب اتنين العنصر كام\nسالب اتنين زي الـ sulphur بالظبط\nالـ chlorine تلاتة والـ sulphur اتنين","countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":9},{"id":"chem-s3-en.video-short-chem.solution-concentration","kind":"short","version":1,"ord":450,"content_lang":"ar-EG","primary_concept_id":"chem.solution-concentration","concepts":[{"concept_id":"chem.solution-concentration","role":"primary"}],"title":"Concentrated and dilute solutions","payload":{"title":"Concentrated and dilute solutions","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: two identical pale beakers (YK.beaker x 320 / x 760, y 1100, 340 × 420) both labelled 'H_2SO_4' (YK.label 52); left with many grey solute dots (YK.swarm, 60), right with few (12), dots jiggling from frame 0; YK.band 'Same acid: !{dilute} vs !{concentrated}?' (88) at 0. Right beaker tag '(dil)' on cue 'dilute', left '(conc.)' on cue 'concentrated'.","tts_text":"نفس الـ sulphuric acid… مرة dilute ومرة concentrated! إيه الفرق؟","screen_text":"Same acid: dilute vs concentrated?"},{"id":"l2","visual":"One beaker centre: a spoon of grey grains drops in and spreads into dots on cue 'دايب'; label 'solute' (48) on cue 'solute'; label 'solution' (52) on cue 'solution'. Prereq chip 'Elements, compounds and mixtures' at line start (after the first 2 s). 'solution' is known (prereq chip); New term 1 = solute. [v5 facts fix: band = screen_text 'Solution: a solute dissolved in a solvent, e.g. water'; label 'solvent' (48) on the liquid on cue 'solvent'.]","tts_text":"الـ solution يعني solute دايب في solvent، زي المية مثلًا.","screen_text":"Solution: a solute dissolved in a solvent, e.g. water"},{"id":"l3","visual":"Left beaker: dots fill densely on cue 'كتير'; a dashed 'volume' bracket (48) on cue 'volume'; label 'concentrated' (52) on cue 'concentrated'. New term 2.","tts_text":"الـ concentrated فيه solute كتير في volume معين.","screen_text":"Concentrated: much solute in a given volume"},{"id":"l4","visual":"Right beaker, same size and bracket: few dots on cue 'قليل'; label 'dilute' (52) on cue 'dilute'. New term 3.","tts_text":"والـ dilute: solute قليل في نفس الـ volume ده.","screen_text":"Dilute: little solute in the same volume"},{"id":"l5","visual":"Water pours into a tall beaker (level 0.4 → 0.9) on cue 'نزوّد'; the same dots spread apart (count unchanged) on cue 'أكتر'.","tts_text":"نزوّد مية؟ الـ solution يبقى dilute أكتر.","screen_text":"Add water → more dilute"},{"id":"l6","visual":"Myth (the lesson's main wrong answer (hook + check): dilute and concentrated acid are different compounds; no misconception recorded): A coral ghost pill 'two different compounds?' spanning both beakers (no invented formula: H_2SO_5 is a real, different compound). Small coral pill on cue 'مختلفة' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'acid' and stays longer on screen. Both labels become the same 'H_2SO_4' (mint) on cue 'acid'; extra water lines fill the dilute one on cue 'بمية'.","tts_text":"ناس فاكرة إنهم compounds مختلفة… لأ، نفس الـ acid، بمية أكتر.","screen_text":"Different compounds? ✕  Same acid, more water ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: sugar 5 g / 50 mL vs 10 g / 500 mL, add water; episode: none). A cup (left) and a bucket (right, custom outlines) on cues 'كوباية' / 'جردل'; one identical spoonful of grains falls into each on cue 'معلقة'; YK.band 'Cup or bucket: more dilute?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"نفس معلقة الملح، مرة في كوباية ومرة في جردل… أنهي dilute أكتر؟","screen_text":"Same spoon of salt: cup or bucket. Which is more dilute?","pause_after_s":2},{"id":"l8","visual":"Answer: the bucket's dots spread thin, the cup's stay crowded on cue 'أكبر'; ONE YK.rightMark on the bucket on cue 'الجردل'.","tts_text":"الجردل: نفس الـ solute في volume أكبر بكتير.","screen_text":"The bucket: same solute, bigger volume ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Concentrated and dilute solutions', line:'Solute in the same volume decides it', t, pulse:[{word:'Solute', at:YK.cue('l9','solute')}, {word:'volume', at:YK.cue('l9','volume')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الفرق: قد إيه solute في الـ volume الواحد.","screen_text":"Solute in the same volume decides it","pause_after_s":1.5}],"logline":"A solution is a solute dissolved in a solvent such as water; a concentrated solution has a large amount of solute in a given volume, a dilute one a small amount; adding water dilutes it and the solute stays the same compound (the (dil) and (conc.) labels on the iron + acid equations, book 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الـ sulphuric acid مرة dilute ومرة\nconcentrated إيه الفرق\nالـ solution يعني solute دايب في solvent\nزي المية مثلًا\nالـ concentrated فيه solute كتير في volume\nمعين\nوالـ dilute solute قليل في نفس الـ volume\nده\nنزوّد مية الـ solution يبقى dilute أكتر\nناس فاكرة إنهم compounds مختلفة لأ نفس الـ\nacid بمية أكتر\nنفس معلقة الملح مرة في كوباية ومرة في جردل\nأنهي dilute أكتر\nالجردل نفس الـ solute في volume أكبر بكتير\nالفرق قد إيه solute في الـ volume الواحد","countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":10},{"id":"chem-s3-en.video-short-acid.metal-acid-reaction","kind":"short","version":1,"ord":452,"content_lang":"ar-EG","primary_concept_id":"acid.metal-acid-reaction","concepts":[{"concept_id":"acid.metal-acid-reaction","role":"primary"}],"title":"Metal + dilute acid","payload":{"title":"Metal + dilute acid","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: YK.beaker(ctx, 540, 1100, 520, 600, {level:0.7, color:'rgba(200,210,230,0.25)', solid:{color:C.steel, p:1}, bubbles:0.8, t}) with a grey zinc piece fizzing from frame 0; label 'Zn' (52) on the piece; YK.band 'Zinc + dilute acid: !{what gas}?' (96) at 0. Bubbles burst faster on cue 'فقاقيع'.","tts_text":"نرمي zinc في dilute acid… فقاقيع! الغاز ده إيه؟","screen_text":"Zinc + dilute acid: what gas?"},{"id":"l2","visual":"Zoom: an 'HCl' pair of discs (H white, Cl green); the Zn disc swaps in for the H on cue 'مكانه'; two H discs pair into a YK.molecule H2 and float up on cue 'ويطرده'; label 'hydrogen' (48) on cue 'hydrogen'.","tts_text":"ده hydrogen: الـ zinc بياخد مكانه في الـ acid، ويطرده.","screen_text":"Hydrogen: zinc takes its place"},{"id":"l3","visual":"The short's ONE written equation (mono 60, y 760): 'Zn + 2HCl -> ZnCl_2 + H_2' on cue 'zinc'; 'ZnCl_2' highlights with tag 'salt' (48) on cue 'salt'. Prereq chip 'Acids, bases and salts' at line start.","tts_text":"والـ zinc chloride هو الـ salt اللي بيتبقى في المحلول.","screen_text":"Zn + 2HCl → ZnCl₂ + H₂"},{"id":"l4","visual":"Equation shrinks to the top; a word chain (Cairo 800 52, y 1000): 'active metal + dilute acid' on cue 'active' → 'salt + hydrogen' on cue 'salt'.","tts_text":"القاعدة: active metal مع dilute acid، يدّي salt و hydrogen غاز.","screen_text":"Active metal + dilute acid → salt + hydrogen"},{"id":"l5","visual":"A short vertical series strip (custom tiles: 'Mg', 'Zn', 'Fe', 'H', 'Cu'; 'H' tile gold) on cue 'series'; tiles above H glow mint on cue 'فوق'; a copper strip in a second beaker stays still (no bubbles) on cue 'copper'. Prereq chip 'Chemical activity series of metals' at line start.","tts_text":"لازم يكون فوق الـ hydrogen في الـ activity series، والـ copper لأ.","screen_text":"Above hydrogen only: copper does not"},{"id":"l6","visual":"Myth (the lesson's 'common mistake' (metal + dilute acid → salt + water); no misconception recorded): A coral ghost chain 'salt + water' over the zinc beaker. Small coral pill on cue 'ومية' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'oxide' and stays longer on screen. The zinc beaker keeps fizzing with 'salt + hydrogen' (mint); a small side tile 'metal oxide + acid → salt + water' (44) on cue 'oxide'.","tts_text":"ناس فاكرة إنه بيدّي salt ومية… لأ، دي لما الـ acid يقابل metal oxide.","screen_text":"Salt + water? ✕  Salt + hydrogen ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: Mg + H2SO4 worked, Zn + H2SO4 blank, Al + HCl, Ca/Cu/CuO/CaO; episode: 2 Fe + HCl count). A magnesium ribbon (custom, label 'Mg') drops into a pale beaker on cue 'magnesium'; bubbles start; two dashed slots '? + ?' (mono 64) on cue 'salt'; YK.band 'Mg + dilute HCl: salt? gas?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب magnesium في dilute hydrochloric acid… يطلع أنهي salt، وأنهي غاز؟","screen_text":"Mg + dilute HCl: which salt? which gas?","pause_after_s":2},{"id":"l8","visual":"Answer: slot 1 fills 'MgCl_2' on cue 'chloride'; slot 2 fills 'H_2' on cue 'hydrogen'; ONE YK.rightMark.","tts_text":"الناتج magnesium chloride، والغاز hydrogen برضه.","screen_text":"MgCl₂ + H₂ ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Metal + dilute acid', line:'Active metal → salt + hydrogen gas' (no formula: ~22 glyphs overflow the card), t, pulse:[{word:'Active', at:YK.cue('l9','active')}, {word:'hydrogen', at:YK.cue('l9','hydrogen')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ active metal يدّي salt و hydrogen غاز.","screen_text":"Active metal → salt + hydrogen gas","pause_after_s":1.5}],"logline":"An active metal above hydrogen in the activity series reacts with a dilute acid to give a salt and hydrogen gas (Zn + 2HCl → ZnCl₂ + H₂); copper does not; a metal oxide gives a salt and water instead (background for iron with dilute acids, book 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zinc في dilute acid فقاقيع الغاز ده\nإيه\nده hydrogen الـ zinc بياخد مكانه في الـ\nacid ويطرده\nوالـ zinc chloride هو الـ salt اللي بيتبقى\nفي المحلول\nالقاعدة active metal مع dilute acid يدّي\nsalt و hydrogen غاز\nلازم يكون فوق الـ hydrogen في الـ activity\nseries والـ copper لأ\nناس فاكرة إنه بيدّي salt ومية لأ دي لما\nالـ acid يقابل metal oxide\nطب magnesium في dilute hydrochloric acid\nيطلع أنهي salt وأنهي غاز\nالناتج magnesium chloride والغاز hydrogen\nبرضه\nالـ active metal يدّي salt و hydrogen غاز","countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":11},{"id":"chem-s3-en.video-short-fe.reaction-dilute-acids","kind":"short","version":1,"ord":454,"content_lang":"ar-EG","primary_concept_id":"fe.reaction-dilute-acids","concepts":[{"concept_id":"fe.reaction-dilute-acids","role":"primary"}],"title":"Iron with dilute acids","payload":{"title":"Iron with dilute acids","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: left, an Fe disc with three Cl discs labelled 'FeCl_3' (YK.label 56) under a 'Cl_2' cloud; right, a pale beaker 'HCl' with an iron nail fizzing and a '?' (mono 80) from frame 0; YK.band 'Cl_2 gives FeCl_3. And !{HCl}?' (96) at 0. Left glows on cue 'chlorine', right on cue 'hydrochloric'.","tts_text":"الـ chlorine بيدّي iron three chloride… طب الـ hydrochloric acid هيدّي إيه؟","screen_text":"Cl₂ gives FeCl₃. And HCl?"},{"id":"l2","visual":"Left panel exits; a mini series strip 'Fe' above gold 'H' on cue 'فوق'; the nail dissolves slowly with bubbles on cue 'فبيدوب'; label 'dilute mineral acids' (48) on cue 'mineral'. Prereq chip 'Metal + dilute acid' at line start. New term 1.","tts_text":"الـ iron فوق الـ hydrogen، فبيدوب في الـ dilute mineral acids ويفوّر.","screen_text":"Iron dissolves in dilute mineral acids"},{"id":"l3","visual":"The short's ONE written equation (mono 60, y 760): 'Fe + 2HCl ->[(dil)] FeCl_2 + H_2' on cue 'hydrochloric'; 'H_2' pulses on cue 'hydrogen'; 'FeCl_2' gold on cue 'chloride'.","tts_text":"مع الـ hydrochloric acid، بيدّي hydrogen و iron two chloride، مش تلاتة.","screen_text":"Fe + 2HCl →(dil) FeCl₂ + H₂"},{"id":"l4","visual":"Below (y 1150): an Fe disc with a '+3' badge meets a rising H2 molecule on cue 'الطالع'; one electron dot passes to Fe on cue 'reduction' and the badge flips '+3 → +2' on cue 'فيرجع'. Prereq chip 'Oxidation and reduction by electrons' at line start.","tts_text":"ليه اتنين؟ الـ hydrogen الطالع بيعمل reduction للـ iron three، فيرجع two.","screen_text":"The produced hydrogen reduces iron (III) to iron (II)"},{"id":"l5","visual":"Myth (concept misconception 1 (TOP)): A coral ghost 'FeCl_3' (YK.label) over the HCl beaker. Small coral pill on cue 'chloride' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'بيفرق' and stays longer on screen. 'FeCl_2' returns bigger with the H2 bubbles highlighted on cue 'hydrogen' (Cl2 gas forms no hydrogen).","tts_text":"ناس فاكرة إنه iron three chloride زي الـ chlorine… لأ، الـ hydrogen هنا بيفرق.","screen_text":"FeCl₃, as with chlorine? ✕  FeCl₂ ✓"},{"id":"l6","style":"curious","visual":"New-case check (lesson: HBr worked/faded, sort Cl2/HCl/S/H2SO4; episode: HBr predict, 2 Fe + HCl count). Equation exits; a new pale beaker labelled 'H_2SO_4 (dil)' with an iron nail fizzing on cue 'sulphuric'; a dashed slot '?' (mono 72) on cue 'salt'; YK.band 'Iron + dilute H_2SO_4: which salt?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l6'), end: YK.cue('l7')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l7').","tts_text":"طب الـ iron في dilute sulphuric acid… أنهي salt هيطلع؟","screen_text":"Iron + dilute H₂SO₄: which salt?","pause_after_s":2},{"id":"l7","visual":"Answer: slot fills 'FeSO_4' (YK.label 64) with tag 'iron (II) sulphate' (44) on cue 'sulphate'; H2 bubbles on cue 'hydrogen'; ONE YK.rightMark.","tts_text":"الناتج هنا iron two sulphate، ومعاه hydrogen برضه.","screen_text":"FeSO₄, iron (II) sulphate + H₂ ✓"},{"id":"l8","visual":"Voiced lock-in: YK.takeaway({title:'Iron with dilute acids', line:'Dilute → iron (II) salt, not iron (III)' (no formula: ~22 glyphs overflow the card), t, pulse:[{word:'Dilute', at:YK.cue('l8','dilute')}, {word:'salt', at:YK.cue('l8','salt')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ dilute بيدّي iron two salt، مش تلاتة.","screen_text":"Dilute → iron (II) salt, not iron (III)","pause_after_s":1.5}],"logline":"Iron dissolves in dilute mineral acids giving iron (II) salts and hydrogen (Fe + 2HCl → FeCl₂ + H₂; Fe + H₂SO₄ → FeSO₄ + H₂), not iron (III) salts, because iron (III) salts are reduced by the produced hydrogen; chlorine gas gives FeCl₃ (book p.21; Q1.2, 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chlorine بيدّي iron three chloride طب\nالـ hydrochloric acid هيدّي إيه\nالـ iron فوق الـ hydrogen فبيدوب في الـ\ndilute mineral acids ويفوّر\nمع الـ hydrochloric acid بيدّي hydrogen و\niron two chloride مش تلاتة\nليه اتنين الـ hydrogen الطالع بيعمل\nreduction للـ iron three فيرجع two\nناس فاكرة إنه iron three chloride زي الـ\nchlorine لأ الـ hydrogen هنا بيفرق\nطب الـ iron في dilute sulphuric acid أنهي\nsalt هيطلع\nالناتج هنا iron two sulphate ومعاه\nhydrogen برضه\nالـ dilute بيدّي iron two salt مش تلاتة","countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":12},{"id":"chem-s3-en.video-short-fe.reaction-conc-sulfuric","kind":"short","version":1,"ord":456,"content_lang":"ar-EG","primary_concept_id":"fe.reaction-conc-sulfuric","concepts":[{"concept_id":"fe.reaction-conc-sulfuric","role":"primary"}],"title":"Iron with hot concentrated sulphuric acid","payload":{"title":"Iron with hot concentrated sulphuric acid","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: a pale beaker labelled 'H_2SO_4 (conc.)' over a burner flame (custom) with an iron nail and gas wisps rising from frame 0; a dashed bubble '?' (mono 72) above the wisps; YK.band 'Hot, concentrated: !{hydrogen} again?' (96) at 0. Flame flares on cue 'سخن'.","tts_text":"نفس الـ sulphuric acid، سخن و concentrated… هيطلع hydrogen برضه؟","screen_text":"Hot, concentrated: hydrogen again?"},{"id":"l2","visual":"A small left inset (x 108-480, y 640-980): a cold dilute beaker 'dil' with H2 bubbles on cue 'hydrogen' and label 'FeSO_4 + H_2' (YK.label 48) on cue 'sulphate'. Prereq chip 'Iron with dilute acids' at line start.","tts_text":"مع الـ dilute كان بيطلع hydrogen، و iron two sulphate بس.","screen_text":"Dilute: FeSO₄ + H₂"},{"id":"l3","visual":"Back to the hot beaker: the wisps become custom SO2 molecules (yellow S + two red O, no preset) labelled 'SO_2' on cue 'dioxide'; a coral ✕ on a ghost H2 on cue 'ميطلعش'. Prereq chip 'Concentrated and dilute solutions' at line start.","tts_text":"لكن الـ concentrated السخن بيطلّع sulphur dioxide، والـ hydrogen ميطلعش.","screen_text":"Hot conc.: SO₂, not H₂"},{"id":"l4","visual":"Three product tags (YK.label 52, y 1300-1500) pop one by one: 'FeSO_4' on cue 'two'; then 'Fe_2(SO_4)_3' on cue 'three'; then 'H_2O' on cue 'مية'.","tts_text":"وكمان بيطلع iron two sulphate، و iron three sulphate، ومعاهم مية.","screen_text":"FeSO₄ + Fe₂(SO₄)₃ + water"},{"id":"l5","visual":"The short's ONE written equation in three rows (mono 52, left-aligned x 108; YK.formula never wraps and the 2-row version is ~1180 px): '3Fe + 8H_2SO_4 ->[conc., Δ]' (y 700) / 'FeSO_4 + Fe_2(SO_4)_3' (y 790) / '+ 4SO_2 + 8H_2O' (y 880); below, three Fe discs: one gets a '+2' badge on cue 'واحد', two get '+3' badges on cue 'تلاتة'.","tts_text":"التلات iron: واحد يبقى اتنين، واتنين يبقوا تلاتة.","screen_text":"3 Fe: one → iron (II), two → iron (III)"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A coral ghost H2 balloon over the hot beaker. Small coral pill on cue 'hydrogen' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'dioxide' and stays longer on screen. SO2 molecules rise bigger on cue 'dioxide'.","tts_text":"ناس فاكرة إنه زي الـ dilute، بيدّي hydrogen… لأ، ده sulphur dioxide بس.","screen_text":"H₂, like the dilute acid? ✕  SO₂ ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: copper + hot conc. acid gas, sorting products; episode: 6 Fe → SO2 count, flame test). The '8H_2SO_4' term glows; its H atoms (white dots) lift out with a '?' (mono 72) on cue 'hydrogen'; YK.band 'No H_2 gas: where did the H go?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب الـ hydrogen اللي في الـ acid… راح فين لو مطلعش غاز؟","screen_text":"No H₂ gas: where does the acid's hydrogen go?","pause_after_s":2},{"id":"l8","visual":"Answer: the white H dots fly into the '8H_2O' term of the equation on cue 'المية'; '8H_2O' turns gold on cue 'تمانية'; ONE YK.rightMark.","tts_text":"راح في المية: تمانية مية في المعادلة.","screen_text":"Into water: 8H₂O ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Iron with hot concentrated sulphuric acid', line:'Two salts + SO₂, not H₂' (no formula: overflows the card), t, pulse:[{word:'salts', at:YK.cue('l9','salts')}, {word:'SO₂', at:YK.cue('l9','dioxide')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"اتنين salts و sulphur dioxide، والـ hydrogen لأ.","screen_text":"Two salts + SO₂, not H₂","pause_after_s":1.5}],"logline":"Hot concentrated sulphuric acid oxidizes iron to a mixture of iron (II) and iron (III) sulphates and gives sulphur dioxide and water, not hydrogen: 3Fe + 8H₂SO₄ (conc., Δ) → FeSO₄ + Fe₂(SO₄)₃ + 4SO₂ + 8H₂O (book 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only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: YK.oxideSkin(ctx, 140, 980, 800, 260, {metal:'Fe', p:0, acid:1, t, acidLabel:'conc. HNO_3'}) with acid particles raining on bare iron from frame 0; YK.band 'Strong acid. Iron !{stops} reacting?' (96, = screen_text) at 0. The particles flash on cue 'nitric'.","tts_text":"الـ dilute acids بتدوّب الـ iron… والـ concentrated nitric acid بيوقّفه؟ إزاي؟","screen_text":"Strong acid. Iron stops reacting?"},{"id":"l2","visual":"Same oxideSkin: layer coverage p 0 → 1 left → right from cue 'layer' to cue 'كله' (non-porous), no built-in label; ONE tag 'thin layer of oxide' (48) on cue 'thin'.","tts_text":"بيعمل thin layer من الـ oxide، تغطي الـ iron كله.","screen_text":"A thin layer of oxide forms"},{"id":"l3","visual":"Aha hold >= 1.5 s: acid particles bounce off the finished layer on cue 'بتحمي'; tag 'no further reaction' (48) on cue 'تفاعل'.","tts_text":"الـ layer دي بتحمي الـ metal من أي تفاعل تاني.","screen_text":"It protects the metal from further reaction"},{"id":"l4","visual":"Label 'Passivity' (64, gold) over the iron on cue 'passivity'; a small inset (x 700-972, y 640-860) of the chromium oxide layer (YK.oxideSkin metal:'Cr') on cue 'chromium'. Prereq chip 'Why chromium resists the effect of atmosphere' at line start. New term 1.","tts_text":"ده اسمه passivity، زي طبقة الـ chromium بالظبط.","screen_text":"Passivity of iron (like chromium's layer)"},{"id":"l5","visual":"Inset exits; a sandpaper block (custom) rubs the layer off on cue 'abrasion' (oxideSkin coverage p 1 → 0.5: the bricks clear from the right where the block rubs; the skin cannot clear a middle patch); then dilute HCl drops strip the rest on cue 'hydrochloric'; label 'abrasion' (48). New term 2.","tts_text":"بس مش دايمة: الـ abrasion أو dilute hydrochloric acid يشيلوها.","screen_text":"Removed by abrasion or dilute HCl"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A coral ghost of the iron block eaten away with pill 'dissolves fast?'. Small coral pill on cue 'بسرعة' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'بيوقّفه' and stays longer on screen. The real block with its full oxide layer returns bigger, particles bouncing, on cue 'بيوقّفه'.","tts_text":"ناس فاكرة إن الـ concentrated nitric acid بيدوّب الـ iron بسرعة… لأ، بيوقّفه.","screen_text":"Dissolves iron fast? ✕  It stops it ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: rubbed nail in CuSO4, fill-blank; episode: iron tank of conc. HNO3). A nail with a dark layer (tag 'passive', 44) on cue 'passive'; sandpaper rubs it bright on cue 'بصنفرة'; it drops into a pale beaker 'H_2SO_4 (dil)' on cue 'sulphuric'; YK.band 'Rubbed passive nail in dilute acid: fizz?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"مسمار passive، حكيناه بصنفرة، ورجّعناه في dilute sulphuric acid… هيفوّر؟","screen_text":"Passive nail, rubbed, into dilute H₂SO₄: fizz?","pause_after_s":2},{"id":"l8","visual":"Answer: H2 bubbles stream from the nail on cue 'بيتفاعل'; tag 'fresh iron' (48) on cue 'الجديد'; ONE YK.rightMark on cue 'أيوه'.","tts_text":"أيوه، الـ layer اتشالت، والـ iron الجديد بيتفاعل.","screen_text":"Yes: layer removed, fresh iron reacts ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Passivity of iron', line:'A thin oxide layer stops further reaction', t, pulse:[{word:'oxide', at:YK.cue('l9','oxide')}, {word:'stops', at:YK.cue('l9','بتوقف')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ oxide layer الرفيعة بتوقف التفاعل.","screen_text":"A thin oxide layer stops further reaction","pause_after_s":1.5}],"logline":"Concentrated nitric acid makes iron passive: a thin layer of oxide forms that protects the metal from further reaction; the layer is removed by abrasion or by dilute hydrochloric acid (book p.21; Q7.10 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dilute acids بتدوّب الـ iron والـ\nconcentrated nitric acid بيوقّفه إزاي\nبيعمل thin layer من الـ oxide تغطي الـ\niron كله\nالـ layer دي بتحمي الـ metal من أي تفاعل\nتاني\nده اسمه passivity زي طبقة الـ chromium\nبالظبط\nبس مش دايمة الـ abrasion أو dilute\nhydrochloric acid يشيلوها\nناس فاكرة إن الـ concentrated nitric acid\nبيدوّب الـ iron بسرعة لأ بيوقّفه\nمسمار passive حكيناه بصنفرة ورجّعناه في\ndilute sulphuric acid هيفوّر\nأيوه الـ layer اتشالت والـ iron الجديد\nبيتفاعل\nالـ oxide layer الرفيعة بتوقف التفاعل","countable":true,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":14},{"id":"chem-s3-en.video-short-fe.oxide-feo","kind":"short","version":1,"ord":493,"content_lang":"ar-EG","primary_concept_id":"fe.oxide-feo","concepts":[{"concept_id":"fe.oxide-feo","role":"primary"}],"title":"Iron(II) oxide FeO","payload":{"title":"Iron(II) oxide FeO","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: a test tube over a flame (YK.tube 540, 1050, 160, 520) with a pale neutral powder labelled 'FeC_2O_4' (YK.label 48; no colour the book does not give) and open air arrows (cyan) curling in from frame 0; YK.band 'Making FeO: heat in !{air}?' (100, formula via YK.label) at 0. Air arrows pulse on cue 'الهوا'.","tts_text":"عايزين نحضّر iron two oxide… نسخّن في الهوا عادي؟","screen_text":"Making FeO: heat in air?"},{"id":"l2","visual":"The tube gets a stopper and the air arrows vanish (tag 'in absence of air', 44) on cue 'هوا'; the short's ONE written equation (mono 56, two rows, y 700/790): 'FeC_2O_4' / '->[Δ, in absence of air] FeO + CO + CO_2' on cue 'oxalate' (book: both conditions over the arrow; '->[a][b]' is not formula syntax); the 'in absence of air' tag leaves when the equation enters (one text block); the powder turns black and CO / CO2 molecules leave on cue 'فيتفكك'. Prereq chip 'Types of chemical reactions' at line start (thermal decomposition). New term 1.","tts_text":"نسخّن الـ iron two oxalate من غير هوا خالص، فيتفكك.","screen_text":"FeC₂O₄ →(Δ, in absence of air) FeO + CO + CO₂"},{"id":"l3","visual":"Side ghost (x 700-972): the stopper lifts, hot air enters and the black powder reddens (FeO black → Fe2O3 red, book colours) on cue 'oxidation'; label 'Fe_2O_3' (YK.label 48) on cue 'السخن'.","tts_text":"لأن الـ iron two oxide بيحصله oxidation بسهولة في الهوا السخن.","screen_text":"FeO is easily oxidized in hot air"},{"id":"l4","visual":"Chain (not an equation): a red 'Fe_2O_3' pile; H2 molecules pass over and leave as H2O on cue 'hydrogen'; the pile turns black 'FeO' on cue 'لسبعمية'; tag '400–700 °C' (mono 48) on cue 'ربعمية'; label 'higher oxides' (44) on cue 'higher'. New term 2.","tts_text":"أو reduction للـ higher oxides بالـ hydrogen، من ربعمية لسبعمية.","screen_text":"Or: H₂ reduces higher oxides, 400–700 °C"},{"id":"l5","visual":"Black FeO powder drops into a beaker of water and settles without dissolving on cue 'insoluble'; label 'black powder' (48) on cue 'سودا'.","tts_text":"وشكله بودرة سودا، و insoluble في المية.","screen_text":"Black powder · insoluble in water"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A coral open tube with air arrows. Small coral pill on cue 'ينفع' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'هيتأكسد' and stays longer on screen. The ghost powder reddens on cue 'هيتأكسد'; the stoppered tube with black FeO returns bigger, tag 'absence of air ✓' (52).","tts_text":"ناس فاكرة إن التسخين في الهوا ينفع… لأ، الـ iron two oxide هيتأكسد.","screen_text":"Heat in air? ✕  Absence of air ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: FeO + 2HCl blank, open-dish red powder; episode: oxalate in nitrogen, FeO + HBr). Equation exits; black FeO powder into a pale beaker 'H_2SO_4 (dil)' on cue 'sulphuric'; dashed slots '? + H_2O' (mono 64) on cue 'salt'; YK.band 'FeO + dilute H_2SO_4: which salt?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب الـ iron two oxide في dilute sulphuric acid… الـ salt هيبقى إيه؟","screen_text":"FeO + dilute H₂SO₄: which salt?","pause_after_s":2},{"id":"l8","visual":"Answer: the slot fills 'FeSO_4' (YK.label 64) with tag 'iron (II) sulphate' (44) on cue 'sulphate'; an Fe badge '+2' with tag 'stays +2' (44) on cue 'فضل'; no bubbles (no gas); ONE YK.rightMark.","tts_text":"يطلع الناتج iron two sulphate ومية، والـ iron فضل اتنين.","screen_text":"FeSO₄ + water: iron stays +2 ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Iron(II) oxide FeO', line:'Absence of air: FeO is easily oxidized' (no formula: ~24 glyphs overflow the card), t, pulse:[{word:'air', at:YK.cue('l9','هوا')}, {word:'oxidized', at:YK.cue('l9','بيتأكسد')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"من غير هوا، لأنه بيتأكسد بسهولة.","screen_text":"Absence of air: FeO is easily oxidized","pause_after_s":1.5}],"logline":"FeO is prepared by heating iron (II) oxalate in absence of air (FeC₂O₄ → FeO + CO + CO₂) or by reducing higher oxides with hydrogen at 400–700 °C; it is a black powder, insoluble in water, easily oxidized in hot air, and gives iron (II) salts and water with dilute mineral acids (book 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نحضّر iron two oxide نسخّن في الهوا\nعادي\nنسخّن الـ iron two oxalate من غير هوا خالص\nفيتفكك\nلأن الـ iron two oxide بيحصله oxidation\nبسهولة في الهوا السخن\nأو reduction للـ higher oxides بالـ\nhydrogen من ربعمية لسبعمية\nوشكله بودرة سودا و insoluble في المية\nناس فاكرة إن التسخين في الهوا ينفع لأ الـ\niron two oxide هيتأكسد\nطب الـ iron two oxide في dilute sulphuric\nacid الـ salt هيبقى إيه\nيطلع الناتج iron two sulphate ومية والـ\niron فضل اتنين\nمن غير هوا لأنه بيتأكسد بسهولة","countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":5},{"id":"chem-s3-en.video-short-fe.oxide-fe2o3","kind":"short","version":1,"ord":495,"content_lang":"ar-EG","primary_concept_id":"fe.oxide-fe2o3","concepts":[{"concept_id":"fe.oxide-fe2o3","role":"primary"}],"title":"Iron(III) oxide Fe₂O₃","payload":{"title":"Iron(III) oxide Fe₂O₃","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: a test tube (YK.tube 540, 1050, 160, 520) of pale crystals (custom, neutral colour, label 'FeSO_4', 48) over a flame, two gas wisps already rising and the solid turning red at the bottom from frame 0 (loop); YK.band 'Heat FeSO_4: !{what red} solid?' (96) at 0. Wisps pulse on cue 'غازين'.","tts_text":"نسخّن iron two sulphate… يطلع غازين، ويفضل حاجة حمرا! إيه؟","screen_text":"Heat FeSO₄: what red solid?"},{"id":"l2","visual":"The red solid is pulled out to centre: an Fe disc badge flips '+2 → +3' on cue 'لتلاتة'; label 'Fe_2O_3' (YK.label 64, red) on cue 'oxide'. Prereq chip 'Oxidation state in compounds' at line start.","tts_text":"الـ iron بيتأكسد لتلاتة، ويبقى iron three oxide أحمر.","screen_text":"Iron +2 → +3: Fe₂O₃ (red)"},{"id":"l3","visual":"The short's ONE written equation (mono 60, y 760): '2FeSO_4 ->[Δ] Fe_2O_3 + SO_2 + SO_3'; 'SO_2' highlights on cue 'dioxide'; then 'SO_3' on cue 'trioxide' (custom molecules: S + 2 O / S + 3 O drift up). New term 1 (sulphur trioxide).","tts_text":"والغازين: sulphur dioxide و sulphur trioxide طالعين سوا.","screen_text":"2FeSO₄ →(Δ) Fe₂O₃ + SO₂ + SO₃"},{"id":"l4","visual":"Chain (not an equation): a pale beaker 'iron (III) salt' gets alkali drops on cue 'alkali'; a reddish-brown Fe(OH)3 precipitate settles (label 'Fe(OH)_3', 48) on cue 'hydroxide'; it is heated and turns red 'Fe_2O_3' with tag 'above 200 °C' (mono 48) on cue 'ميتين'. Prereq chip 'Types of chemical reactions' at line start (precipitation).","tts_text":"أو alkali على iron three salt، والـ hydroxide يتسخّن فوق ميتين.","screen_text":"Or: Fe(OH)₃ above 200 °C → Fe₂O₃"},{"id":"l5","visual":"A YK.ore hematite (r 130, label:true) on cue 'hematite'; a red paint swatch (custom brush stroke) on cue 'paints'. Prereq chip 'Important iron ores' at line start.","tts_text":"في الطبيعة hematite، وبنستخدمه في الـ paints الحمرا.","screen_text":"Hematite · red paints"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): Coral ghost products 'FeO' and a single 'SO_2' over the tube. Small coral pill on cue 'واحد' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'اتنين' and stays longer on screen. The book products return bigger: red 'Fe_2O_3' + two gas labels 'SO_2', 'SO_3' on cue 'اتنين'.","tts_text":"ناس فاكرة إنه بيدّي iron two oxide، أو غاز واحد… لأ، اتنين.","screen_text":"FeO? One gas? ✕  Fe₂O₃ + SO₂ + SO₃ ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: alkali + Fe(NO3)3, FeSO4 heating, Fe2O3 + HCl balance; episode: iron (III) sulphate + alkali → heat). Red Fe2O3 into a hot beaker 'H_2SO_4 (conc.)' over a flame on cue 'sulphuric'; dashed slots '? + H_2O' (mono 64) on cue 'salt'; YK.band 'Fe_2O_3 + hot conc. H_2SO_4: which salt?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب الـ iron three oxide مع concentrated sulphuric acid سخن… الـ salt هيبقى إيه؟","screen_text":"Fe₂O₃ + hot conc. H₂SO₄: which salt?","pause_after_s":2},{"id":"l8","visual":"Answer: slot fills 'Fe_2(SO_4)_3' (YK.label 60) with tag 'iron (III) sulphate' (44) on cue 'sulphate'; Fe badge '+3' with tag 'stays +3' (44) on cue 'فضل'; ONE YK.rightMark.","tts_text":"يطلع iron three sulphate ومية، والـ iron فضل تلاتة.","screen_text":"Fe₂(SO₄)₃ + water: iron stays +3 ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Iron(III) oxide Fe₂O₃', line:'Heating FeSO₄ → Fe₂O₃ + SO₂ + SO₃' (no formula: the line already carries the equation and the formula overflows), t, pulse:[{word:'Fe₂O₃', at:YK.cue('l9','oxide')}, {word:'SO₂', at:YK.cue('l9','وغازين')}, {word:'SO₃', at:YK.cue('l9','وغازين')}]}) from line start (pulse words normalise to 'feo' / 'so' / 'so': the two 'so' pulses take SO₂ then SO₃; voiced 9 tokens accepted: the 9th is the clitic الـ), held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ iron two sulphate يدّي iron three oxide وغازين.","screen_text":"Heating FeSO₄ → Fe₂O₃ + SO₂ + SO₃","pause_after_s":1.5}],"logline":"Fe₂O₃ is obtained by heating iron (II) sulphate (2FeSO₄ → Fe₂O₃ + SO₂ + SO₃) or by heating above 200 °C the reddish-brown Fe(OH)₃ precipitated by an alkali from an iron (III) salt; it occurs as hematite, is used in red pigments in paints, and gives iron (III) salts and water with hot concentrated acids (book 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iron two sulphate يطلع غازين ويفضل\nحاجة حمرا إيه\nالـ iron بيتأكسد لتلاتة ويبقى iron three\noxide أحمر\nوالغازين sulphur dioxide و sulphur\ntrioxide طالعين سوا\nأو alkali على iron three salt والـ\nhydroxide يتسخّن فوق ميتين\nفي الطبيعة hematite وبنستخدمه في الـ\npaints الحمرا\nناس فاكرة إنه بيدّي iron two oxide أو غاز\nواحد لأ اتنين\nطب الـ iron three oxide مع concentrated\nsulphuric acid سخن الـ salt هيبقى إيه\nيطلع iron three sulphate ومية والـ iron\nفضل تلاتة\nالـ iron two sulphate يدّي iron three\noxide وغازين","countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":6},{"id":"chem-s3-en.video-short-fe.oxide-fe3o4","kind":"short","version":1,"ord":497,"content_lang":"ar-EG","primary_concept_id":"fe.oxide-fe3o4","concepts":[{"concept_id":"fe.oxide-fe3o4","role":"primary"}],"title":"Magnetic iron oxide Fe₃O₄","payload":{"title":"Magnetic iron oxide Fe₃O₄","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: a black YK.ore magnetite (r 140, y 900, label:false) clinging to a YK.magnet above it, with two empty salt slots below it (dashed, y 1400) blinking from frame 0; YK.band 'One oxide. !{Two} salts?' (110) at 0. The two slots flash on cue 'salts'.","tts_text":"نفس الـ oxide يدّي اتنين salts مختلفين؟ إزاي ده؟","screen_text":"One oxide. Two salts?"},{"id":"l2","visual":"Label 'Fe_3O_4' (YK.label 72) on cue 'magnetic'; the magnet pull tightens and the ore snaps up on cue 'جامد'; tag 'strong magnet' (48).","tts_text":"ده الـ magnetic iron oxide، أسود وبيتشد للمغناطيس جامد.","screen_text":"Fe₃O₄: magnetic iron oxide, a strong magnet"},{"id":"l3","visual":"The ore splits into two chunks in book colours: a black 'FeO' chunk holding one Fe disc '+2' on cue 'two'; then a red 'Fe_2O_3' chunk holding two Fe discs '+3' on cue 'three'; bracket 'mixed oxide' (52) on cue 'mixed'. New term 1.","tts_text":"بيعتبر mixed oxide، فيه iron two و iron three سوا.","screen_text":"Mixed oxide: FeO + Fe₂O₃"},{"id":"l4","visual":"Chain (not an equation): red 'Fe_2O_3' pile; YK.molecule CO passes over on cue 'monoxide' and the pile turns black 'Fe_3O_4' on cue 'تلتمية'; tag '230–300 °C' (mono 48) on cue 'ميتين'. Prereq chip 'Iron(III) oxide Fe₂O₃' at line start.","tts_text":"بيتحضّر بالـ carbon monoxide على iron three oxide، من ميتين وتلاتين لحد تلتمية.","screen_text":"Fe₂O₃ + CO (230–300 °C) → Fe₃O₄"},{"id":"l5","visual":"The short's ONE written equation in three rows (mono 52, left-aligned x 108; the 2-row version is ~1050 px): 'Fe_3O_4 + 4H_2SO_4 ->[conc., Δ]' (y 700) / 'FeSO_4 + Fe_2(SO_4)_3' (y 790) / '+ 4H_2O' (y 880) on cue 'concentrated'; the two salt slots fill: 'FeSO_4' from the FeO half on cue 'two'; then 'Fe_2(SO_4)_3' from the Fe2O3 half on cue 'three'.","tts_text":"وفي الـ concentrated acid السخن، بيدّي iron two salt و iron three salt سوا.","screen_text":"Fe₃O₄ + 4H₂SO₄ →(conc., Δ) FeSO₄ + Fe₂(SO₄)₃ + 4H₂O"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A coral ghost with only one slot filled 'Fe_2(SO_4)_3?'. Small coral pill on cue 'واحد' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'دليل' and stays longer on screen. Both slots glow mint with tag 'proof: mixed oxide' (48) on cue 'دليل'.","tts_text":"ناس فاكرة إنه بيدّي salt واحد… لأ، الاتنين، وده دليل.","screen_text":"One salt? ✕  Two salts: the proof ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: proof MCQ, H2 at 400-700 °C → FeO, HCl balance; episode: hot conc. acid salt count, heated in air). A red-hot iron bar with steam wisps (custom) on cue 'steam'; a black crust forms on cue 'black'; empty slots '?' on cue 'salt'; YK.band 'Steam on red-hot iron: how many salts?'. Prereq chip 'Effect of air and water vapour' at line start. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب الـ black oxide من steam على iron سخن… كام salt يدّي؟","screen_text":"Black oxide from steam on red-hot iron: how many salts?","pause_after_s":2},{"id":"l8","visual":"Answer: the crust gets label 'Fe_3O_4' (YK.label 56) and the magnet pulls it on cue 'magnetic'; two slots fill on cue 'اتنين'; ONE YK.rightMark.","tts_text":"اتنين، لأن الناتج magnetic iron oxide برضه.","screen_text":"Two: it is Fe₃O₄ ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Magnetic iron oxide Fe₃O₄', line:'Two salts prove it is a mixed oxide', formula:'Fe_3O_4 = FeO + Fe_2O_3', t, pulse:[{word:'salts', at:YK.cue('l9','salts')}, {word:'mixed', at:YK.cue('l9','mixed')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"اتنين salts، يعني mixed oxide فعلًا.","screen_text":"Two salts prove it is a mixed oxide","pause_after_s":1.5}],"logline":"Fe₃O₄ (magnetite) is a black, strong magnet and a mixed iron (II)/iron (III) oxide: made by hot air or steam on red-hot iron, or by reducing Fe₂O₃ with CO at 230–300 °C; with hot concentrated acids it gives iron (II) and iron (III) salts, proving it is a mixed oxide (book pp.23-24).","concept_ids":["fe.oxide-fe3o4"]},"layer":null,"layer_fallback":false,"images":{"cover_9x16":"https://cdn.yaani.ai/files/a35086171186220e8863dcdf38c9f5c2db2e4053d3061cbb022acd0d77ef4fc5.jpg","hero_21x9":"https://cdn.yaani.ai/files/32dca6c42c007863d0bc7ccac7b170f987edb88e4c8c223c3a1ba299fa90dbaa.jpg","hero_4x5":"https://cdn.yaani.ai/files/672af5ef5b77097a571bf97fb48452252be1a5537301d1031a59ab08eb54fefa.jpg","og":"https://cdn.yaani.ai/files/927440223e76845153eb7ae404bd6f294d80e665c45d16ae362e18938acb8ebb.jpg","poster":"https://cdn.yaani.ai/files/8cbc0b2ea66199d6c30757be49e086e343387eb4ba722a76cdb6925de0bad3ce.jpg","thumbnail":"https://cdn.yaani.ai/files/3979ad7c31d30cf23a4d24f71eb25d7fbf65905a2faf3d33b77219efb7905b35.jpg"},"thumbnail_variant":"a","files":[{"role":"captions","key":"ar-EG","url":"https://cdn.yaani.ai/files/40a31f621c5fa5d1c06ea545a372385621c8d04ac9dc5ab546f9ee9911b1f24f.vtt","mime":"text/vtt","size":1003},{"role":"cover_9x16","key":"","url":"https://cdn.yaani.ai/files/a35086171186220e8863dcdf38c9f5c2db2e4053d3061cbb022acd0d77ef4fc5.jpg","mime":"image/jpeg","size":84413},{"role":"cover_9x16","key":"a/1080x1920.avif","url":"https://cdn.yaani.ai/files/a181db23f947ff417d8d6213640082259750f81b284492dd63254273626e25f0.avif","mime":"image/avif","size":11821},{"role":"cover_9x16","key":"a/1080x1920.jpg","url":"https://cdn.yaani.ai/files/a35086171186220e8863dcdf38c9f5c2db2e4053d3061cbb022acd0d77ef4fc5.jpg","mime":"image/jpeg","size":84413},{"role":"cover_9x16","key":"a/1080x1920.png","url":"https://cdn.yaani.ai/files/14f64e970a3cd8cde751d9fbd1dfdf3d7076a55fca902c9644058354f6d005a2.png","mime":"image/png","size":127327},{"role":"cover_9x16","key":"a/1080x1920.webp","url":"https://cdn.yaani.ai/files/4d96233be1bd5444356a9fc266f2671df82e2099f14bfc364b5f3ec1dc070974.webp","mime":"image/webp","size":22332},{"role":"cover_9x16","key":"a/540x960.avif","url":"https://cdn.yaani.ai/files/67b5b4d89ecc567693f6db38ac7140f7808b1937b8d3d507a763b52e2451dcbb.avif","mime":"image/avif","size":6139},{"role":"cover_9x16","key":"a/540x960.jpg","url":"https://cdn.yaani.ai/files/fcf8339cd44aa31bb92a4b4d011b2bd014e95d9960b257ee597932b96715da65.jpg","mime":"image/jpeg","size":34975},{"role":"cover_9x16","key":"a/540x960.webp","url":"https://cdn.yaani.ai/files/574bdf22c3ef4a968e97342daa2fe2237ec617c03868cc895668cbed91ae1ae8.webp","mime":"image/webp","size":10188},{"role":"cover_9x16","key":"b/1080x1920.avif","url":"https://cdn.yaani.ai/files/1b52e26efef4124ab4adbfd1b8cdcd8cd8c0337efe817649f79c5df4665ee835.avif","mime":"image/avif","size":10602},{"role":"cover_9x16","key":"b/1080x1920.jpg","url":"https://cdn.yaani.ai/files/4107d6d294fb57e0e7f15119652704aaa2bd2bab798793fec2fb4c5682c419d6.jpg","mime":"image/jpeg","size":89622},{"role":"cover_9x16","key":"b/1080x1920.png","url":"https://cdn.yaani.ai/files/b6373e51ee6c5d85227fa6686ce3c34cbd40e181063239dde09f8973955529df.png","mime":"image/png","size":109843},{"role":"cover_9x16","key":"b/1080x1920.webp","url":"https://cdn.yaani.ai/files/68019c20d24169ca8614ee0defce7f39b5b8944dc229df059c62793a86fad2f2.webp","mime":"image/webp","size":20720},{"role":"cover_9x16","key":"b/540x960.avif","url":"https://cdn.yaani.ai/files/c2e916ea665c52a9b3313f2356c32a3544d14b43697edb0ba81092f3046978d5.avif","mime":"image/avif","size":5658},{"role":"cover_9x16","key":"b/540x960.jpg","url":"https://cdn.yaani.ai/files/68c0f974ffbe1ea309a170d30a23e8ae36884d29bb28fd27da89aa81ec2787ae.jpg","mime":"image/jpeg","size":40213},{"role":"cover_9x16","key":"b/540x960.webp","url":"https://cdn.yaani.ai/files/f0d3bd22f8eabd4398353b536ab55870cac0938b0aea170f04708459d66f1d0a.webp","mime":"image/webp","size":10422},{"role":"hero_21x9","key":"","url":"https://cdn.yaani.ai/files/32dca6c42c007863d0bc7ccac7b170f987edb88e4c8c223c3a1ba299fa90dbaa.jpg","mime":"image/jpeg","size":88700},{"role":"hero_21x9","key":"a/1680x720.avif","url":"https://cdn.yaani.ai/files/b90e29b7e90ee2097838518f874ffb323a9ac0f875ad87c707b5e1708142011c.avif","mime":"image/avif","size":8174},{"role":"hero_21x9","key":"a/1680x720.jpg","url":"https://cdn.yaani.ai/files/5d8ec9193f0560e782a07c9f8514c22948d70af884bbd01094a76f1e8e5d314b.jpg","mime":"image/jpeg","size":50332},{"role":"hero_21x9","key":"a/1680x720.webp","url":"https://cdn.yaani.ai/files/80e569d01b5c47f4ed96741464eeccf7aa0e1ffec53110fb45444c2b2e49cab8.webp","mime":"image/webp","size":13578},{"role":"hero_21x9","key":"a/2520x1080.avif","url":"https://cdn.yaani.ai/files/92c84019569deadd6732be544c568903c35ae9a8a622328dfcca03c530b2d745.avif","mime":"image/avif","size":10937},{"role":"hero_21x9","key":"a/2520x1080.jpg","url":"https://cdn.yaani.ai/files/32dca6c42c007863d0bc7ccac7b170f987edb88e4c8c223c3a1ba299fa90dbaa.jpg","mime":"image/jpeg","size":88700},{"role":"hero_21x9","key":"a/2520x1080.png","url":"https://cdn.yaani.ai/files/17540b34c152c2e4dcf29a110359f29cbf2de73412db2b902de8151cfca0efe2.png","mime":"image/png","size":131190},{"role":"hero_21x9","key":"a/2520x1080.webp","url":"https://cdn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الـ oxide يدّي اتنين salts مختلفين\nإزاي ده\nده الـ magnetic iron oxide أسود وبيتشد\nللمغناطيس جامد\nبيعتبر mixed oxide فيه iron two و iron\nthree سوا\nبيتحضّر بالـ carbon monoxide على iron\nthree oxide من ميتين وتلاتين لحد تلتمية\nوفي الـ concentrated acid السخن بيدّي iron\ntwo salt و iron three salt سوا\nناس فاكرة إنه بيدّي salt واحد لأ الاتنين\nوده دليل\nطب الـ black oxide من steam على iron سخن\nكام salt يدّي\nاتنين لأن الناتج magnetic iron oxide برضه\nاتنين salts يعني mixed oxide فعلًا","countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":7},{"id":"chem-s3-en.video-short-fe.conversions","kind":"short","version":1,"ord":499,"content_lang":"ar-EG","primary_concept_id":"fe.conversions","concepts":[{"concept_id":"fe.conversions","role":"primary"}],"title":"Iron and its oxides: reaction diagrams","payload":{"title":"Iron and its oxides: reaction diagrams","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini"},"aspect":"9:16","format":"short","script":[{"id":"l1","style":"curious","visual":"[Director pre-empt, all lines: page.html adds <script> tags for lib/short.js and lib/beats.js after lib/flow.js (template.html lacks only these two; it already loads matter.js, industry.js, lab.js); every YK.band item at <= 0 is on screen at frame 0 (S13); prereq chips = YK.chip kind 'prereq' (map title_en exactly) at x 108, y 600, <= 2 s, one at a time, never inside the first 2 s; one stamp per beat; <= 7 words per text block (check question <= 14, takeaway line <= 10); <= 1 written equation on screen at a time (other steps as molecules / chains); YK.cue needles are substring matches (k given where an earlier word of the line contains the needle); every needle below is a whole word of that line's tts_text; no made-up quantities (only book values); solutions drawn pale/neutral (no ion colours); substance colours only from the book (FeO black, Fe2O3 red, Fe(OH)3 reddish brown, Fe3O4 black); English only, LTR; key content x 108-972 / y 240-1680; look at stills before render.; Director pass v2 adds: YK.takeaway formula only when it fits the 736 px text width at 60 px mono (~18 glyphs), else no formula (the body already wrote the equation); YK.lattice draws no element symbols and no bond lines (label atoms with YK.label / draw links from the returned pos()); YK.band strings use YK.formula syntax (H_2SO_4, Fe_2O_3); written equations wider than 864 px at their size are split into rows (YK.formula never wraps).] Frame 0 complete: a red 'Fe_2O_3' pile (y 1000) with YK.molecule CO streaming over it and three dashed product slots below (y 1400) cycling '?' from frame 0; YK.band 'Same CO, same oxide. !{Different}?' (96) at 0. The CO stream brightens on cue 'carbon'.","tts_text":"نفس الـ carbon monoxide، ونفس الـ oxide… والناتج مختلف؟","screen_text":"Same CO, same oxide. Different products?"},{"id":"l2","visual":"A vertical ladder (custom, x 300, y 640-1600; rungs top → bottom by oxygen per Fe: 'Fe_2O_3', 'Fe_3O_4', 'FeO', 'Fe', YK.label 52); an up arrow (coral) with tag 'oxidation' on cue 'oxidation'; a down arrow (cyan) with tag 'reduction' on cue 'reduction'. Prereq chip 'Oxidation and reduction by oxygen' is NOT shown (not a map prereq here).","tts_text":"لفوق oxidation، ولتحت reduction بيشيل oxygen منه.","screen_text":"Up: oxidation (+O) · down: reduction (−O)"},{"id":"l3","visual":"A cyan arrow drops one rung 'Fe_2O_3' → 'Fe_3O_4' with tag '230–300 °C' (mono 48) on cue 'ميتين'; the 'Fe_3O_4' rung glows black on cue 'magnetic' (the FeO rung stays dim, kept for the check). Prereq chip 'Magnetic iron oxide Fe₃O₄' at line start.","tts_text":"من ميتين وتلاتين لحد تلتمية، الـ carbon monoxide يدّي magnetic iron oxide بس.","screen_text":"Fe₂O₃ + CO, 230–300 °C → Fe₃O₄"},{"id":"l4","visual":"A long cyan arrow drops 'Fe_2O_3' → 'Fe' (skipping the dim FeO rung, unlabelled) on cue 'كله'; the short's ONE written equation in two rows right of the ladder (mono 48, left x 420, y 1400/1480; one row is ~820 px and the column is 552): 'Fe_2O_3 + 3CO' / '->[> 700 °C] 2Fe + 3CO_2' on cue 'سبعمية'. Prereq chip 'Reduction in the blast furnace' at line start.","tts_text":"وفوق سبعمية، نفس الـ carbon monoxide يشيل الـ oxygen كله، ويفضل الـ iron لوحده.","screen_text":"Fe₂O₃ + 3CO →(> 700 °C) 2Fe + 3CO₂"},{"id":"l5","visual":"A coral up arrow 'Fe_3O_4' → 'Fe_2O_3' with tag 'heat in air' (44) on cue 'الهوا'; red O dots attach on cue 'يزيد'.","tts_text":"ولفوق: تسخين في الهوا، فالـ oxygen يزيد تاني.","screen_text":"Up: heat in air adds oxygen"},{"id":"l6","visual":"Myth (concept misconception 1 (TOP)): A coral ghost card 'CO -> always Fe'. Small coral pill on cue 'الناتج' + YK.wrongMark on cue 'لأ', both gone 0.4 s later; the right version enters bigger + ONE YK.rightMark on cue 'بتفرق' and stays longer on screen. The two CO arrows (230–300 °C | > 700 °C) glow side by side with tag 'temperature decides' (52) on cue 'بتفرق'.","tts_text":"ناس فاكرة إن نفس الـ reagent يعني نفس الناتج… لأ، الحرارة بتفرق.","screen_text":"Same reagent, same product? ✕  Temperature decides ✓"},{"id":"l7","style":"curious","visual":"New-case check (lesson: sort CO/H2 rungs, Fe3O4 → Fe, FeO → Fe2O3; episode: ladder walk, X/Y/Z chain, Q6). A thermometer tag '500 °C' (mono 56) slides between the two drawn CO arrows on cue 'خمسمية'; a dashed '?' arrow from 'Fe_2O_3' on cue 'يطلع'; YK.band 'CO at 500 °C: product?'. YK.thinkRing(ctx, t, 540, 1520, {start: YK.cueEnd('l7'), end: YK.cue('l8')}) through the stitched silence (pause_after_s 2.0); no answer on screen before YK.cue('l8').","tts_text":"طب نفس الـ carbon monoxide عند خمسمية درجة… يطلع إيه؟","screen_text":"CO over Fe₂O₃ at 500 °C: product?","pause_after_s":2},{"id":"l8","visual":"Answer: the dim 'FeO' rung lights (black) on cue 'oxide'; tag '400–700 °C' (mono 48) on cue 'النص'; ONE YK.rightMark.","tts_text":"الـ iron two oxide، لأن خمسمية في النص، بين الاتنين.","screen_text":"FeO: the middle rung (400–700 °C) ✓"},{"id":"l9","visual":"Voiced lock-in: YK.takeaway({title:'Iron and its oxides: reaction diagrams', line:'Conditions decide the product', t, pulse:[{word:'Conditions', at:YK.cue('l9','conditions')}, {word:'product', at:YK.cue('l9','الناتج')}]}) from line start, held >= 2.5 s (pause_after_s 1.5). Loop (S5): last 0.8 s returns to the frame-0 composition.","tts_text":"الـ conditions هي اللي بتحدد الناتج.","screen_text":"Conditions decide the product","pause_after_s":1.5}],"logline":"In conversion diagrams the conditions decide the product: arrows up add oxygen (heating in air), arrows down remove it; CO with Fe₂O₃ gives Fe₃O₄ at 230–300 °C, FeO at 400–700 °C and iron above 700 °C (book Q6 p.26; pp.18, 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الـ carbon monoxide ونفس الـ oxide\nوالناتج مختلف\nلفوق oxidation ولتحت reduction بيشيل\noxygen منه\nمن ميتين وتلاتين لحد تلتمية الـ carbon\nmonoxide يدّي magnetic iron oxide بس\nوفوق سبعمية نفس الـ carbon monoxide يشيل\nالـ oxygen كله ويفضل الـ iron لوحده\nولفوق تسخين في الهوا فالـ oxygen يزيد تاني\nناس فاكرة إن نفس الـ reagent يعني نفس\nالناتج لأ الحرارة بتفرق\nطب نفس الـ carbon monoxide عند خمسمية درجة\nيطلع إيه\nالـ iron two oxide لأن خمسمية في النص بين\nالاتنين\nالـ conditions هي اللي بتحدد الناتج","countable":true,"session_id":"chem-s3-en.ch1.s9","session_no":9,"session_ord":8},{"id":"chem-s3-en.video-walkthrough-phys.electric-charges","kind":"walkthrough","version":5,"ord":2,"content_lang":"ar-EG","primary_concept_id":"phys.electric-charges","concepts":[{"concept_id":"phys.electric-charges","role":"primary"}],"title":"Electric charges: attraction and repulsion: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-phys.electric-charges v1 (s1 hook: two electrons attract/repel MCQ incl. option 'nothing happens, electrons are too small'; s2 KeyTerm 'Electric charges' definition 'two kinds of charge, positive (+) and negative (−); like charges repel; unlike charges attract' + atom text 'protons in the nucleus positive, electrons negative, so the nucleus attracts the electrons' + Misconception trap 'Electrons in an atom feel the pull of the nucleus and nothing else'; s3 sliders: more charge -> stronger attraction, smaller distance -> stronger, same rules for electron repulsion; s4 MCQ X 11 protons vs Y 17 protons at about the same distance (used as the worked example); s5 recap + exam callout 'nuclear attraction' / 'repulsion force' (Ch.1 p.12-13)). Concept phys.electric-charges v2 (no recorded misconceptions: s2 refutes the lesson's trap (s2l21-s2l23) and the hook's 'too small' option (s2l17-s2l19)). Book Ch.1 pp.12-13 'Atomic radius': nearly constant from (Cr) to (Cu) due to two opposite factors, nuclear attraction to electrons vs repulsion force between 3d electrons. Dependents named in s4 (titles as chips, no new terms spoken): atom.structure 'Structure of the atom', pt.atomic-radius-trend 'Atomic radius trend', in-book te.atomic-radius 'Atomic radius: nearly constant'; phys.electric-current not named (not in this chapter's book text). Terms: s1 = electric charge (positive/negative), attract, repel (3); s2 = like charges, unlike charges, atoms, nucleus, protons, electrons, nuclear attraction, repulsion force, force (glossed as pull or push); s3/s4 none. Worked example = lesson s4 X/Y case (3 steps); self-check NEW case: one nucleus, near vs far electron (distance rule), pause 4.0 s, answer + reason. Predicts: s2l16 (~2:30, pause 3 s) and s3l11 (~3:50). Estimate: 54 lines, 581 narration words at ~2.4 w/s + 30 s pauses + joins = ~290 s (4.8 min); recap s4l5-s4l7 ~14 s. not-in-source: rubbing a balloon on hair gives the balloon and the hair different (opposite) charges, so hair is attracted and two rubbed balloons repel (everyday anchor); atoms are tiny particles that things (water, iron, hair) are made of; the nucleus is the centre of the atom and electrons move around it; a nearer electron is pulled more strongly by the same nucleus (lesson rule 'smaller distance -> stronger attraction' applied to a new case).","title":"Electric charges: attraction and repulsion: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor on the stage: YK.bodyShape(ctx, 1240, 760, 560) (head + shoulders) with ~20 short hair strands drawn as line paths on the head top; a balloon = YK.atomDisc(ctx, x, y, 90, {label:'', symbol:false, color:C.pink}) + a thin string path. On cue 'تحك' the balloon rubs side to side over the hair (sine on x for 1.5 s); on cue 'ابعدها' it moves up-right to (1560, 400). Text panel: YK.fpara 'Rub a balloon on your hair' (44).","tts_text":"جرّب تحُكّ بالونة في شَعرك شوية، وبعدين ابعدها بالراحة.","screen_text":"Rub a balloon on your hair","pause_after_s":0.4},{"id":"s1l3","visual":"Same shot: the hair strands bend and stretch towards the balloon on cue 'ويتشد' (each strand's tip interpolates towards the balloon centre, YK.prog over 0.8 s); a thin mint YK.arrow from the hair to the balloon on the same cue. Text panel YK.fpara 'The hair rises towards the balloon'.","tts_text":"هتلاقي شَعرك بيقف ويتشِدّ ناحية البالونة، من غير ما تلمسه.","screen_text":"The hair rises towards the balloon","pause_after_s":0.4},{"id":"s1l4","visual":"Picture change: two pink balloons (YK.atomDisc, r 80, symbol:false) hanging on strings from one point at (1300, 180); on cue 'وقرّبتهم' they hang close, on cue 'هيزقّوا' they swing apart (string angle ±25°) with two coral outward YK.arrow. Text panel YK.fpara 'Two rubbed balloons push apart'.","tts_text":"ولو حكّيت بالونتين وقرّبتهم من بعض، هيزقّوا بعض بعيد.","screen_text":"Two rubbed balloons push apart","pause_after_s":0.4},{"id":"s1l5","visual":"Text panel: YK.termCard({term:'electric charge', align:'left'}) at (96, 220) on cue 'electric'. Stage: the balloon pair stays (dimmed to 35%); a small gold YK.glowCircle pulses on each balloon on cue 'charge'.","tts_text":"اللي بيعمل كده حاجة اسمها electric charge، يعني شُحنة كهربا.","screen_text":"electric charge","pause_after_s":0.4},{"id":"s1l6","visual":"The term card gets its definition: YK.termCard({term:'electric charge', def:'two kinds: positive (+) and negative (−)', keys:['positive','negative']}). Stage: two big charge spheres YK.atomDisc(ctx, 1150, 600, 120, {label:'+', color:C.pink}) on cue 'positive' and YK.atomDisc(ctx, 1500, 600, 120, {label:'−', color:C.cyan}) on cue 'negative' (same visual language as the short: pink '+', cyan '−'); tags 'positive' / 'negative' (YK.tag 40) under them on the same cues.","tts_text":"والـ charge نوعين: positive وعلامته زائد، و negative وعلامته ناقص.","screen_text":"two kinds: positive (+) and negative (−)","pause_after_s":0.4},{"id":"s1l7","visual":"Back to the anchor shot (head + one balloon): on cue 'charges' small cyan '−' signs (YK.label 40) pop onto the balloon and small pink '+' signs onto the hair strands (seeded positions, YK.rng). Text panel YK.fpara 'Balloon and hair: different charges'.","tts_text":"لما حكّيت البالونة، البالونة والشَعر خدوا charges مختلفة عن بعض.","screen_text":"Balloon and hair: different charges","pause_after_s":0.4},{"id":"s1l8","visual":"YK.termCard({term:'attract', def:'pull towards each other'}) replaces the previous card on cue 'attract'. Stage: hair strands bend to the balloon again; a mint YK.arrow pair pointing inwards between hair and balloon on cue 'يشدّوا'.","tts_text":"ولما حاجتين يشدّوا بعض لبعض، بنقول إنهم بيعملوا attract، يعني تجاذُب.","screen_text":"attract: pull towards each other","pause_after_s":0.4},{"id":"s1l9","visual":"YK.termCard({term:'repel', def:'push each other away'}) on cue 'repel'. Stage: the two hanging balloons from s1l4 return and swing apart on cue 'يزقّوا' with coral outward YK.arrow.","tts_text":"ولما يزقّوا بعض بعيد، بنقول إنهم بيعملوا repel، يعني تنافُر.","screen_text":"repel: push each other away","pause_after_s":0.4},{"id":"s1l10","visual":"Stage split: left the hair+balloon pair with a mint 'attract' YK.tag (cue 'attract'), right the two balloons with a coral 'repel' YK.tag (cue 'repel'); a big gold '?' path between them. Text panel YK.fpara 'When do charges attract, and when do they repel?' (48).","tts_text":"طب إمتى الـ charges تعمل attract، وإمتى تعمل repel؟ خلّينا نشوف.","screen_text":"When do charges attract, and when do they repel?","pause_after_s":1},{"id":"s2l2","visual":"YK.termCard({term:'like charges', def:'the same kind (+ and +, or − and −)'}) on cue 'like'. Stage: two rows of charge spheres (YK.atomDisc r 90): row 1 pink '+' and '+' at y 420, row 2 cyan '−' and '−' at y 760, close together (x 1180 / 1440), popping in on cue 'النوع'.","tts_text":"لو الـ charges من نفس النوع، بنسميهم like charges، يعني شحنات متشابهة.","screen_text":"like charges: the same kind (+ and +, or − and −)","pause_after_s":0.3},{"id":"s2l3","visual":"Both rows slide apart (x 1180→1000 and 1440→1620, YK.tween outBack) on cue 'repel' with coral outward YK.arrow pairs; text panel rule line YK.fpara 'Like charges repel' (52, coral key word 'repel') under the card.","tts_text":"والقاعدة الأولى: الـ like charges بتعمل repel، بتزُقّ بعض بعيد.","screen_text":"Like charges repel","pause_after_s":0.3},{"id":"s2l4","visual":"Picture change: the like rows fade to the top-left corner of the stage (40%, kept as a reminder); a new pair pink '+' (x 1120) and cyan '−' (x 1500) at y 640 on cue 'مختلفة' (#0); YK.termCard({term:'unlike charges', def:'different kinds (+ and −)'}) on cue 'unlike'.","tts_text":"ولو الـ charges مختلفة، بنسميهم unlike charges، يعني شحنات مختلفة.","screen_text":"unlike charges: different kinds (+ and −)","pause_after_s":0.3},{"id":"s2l5","visual":"The '+' and '−' pair drift towards each other (x 1120→1240, 1500→1380) on cue 'attract' with mint inward YK.arrow pair; rule line YK.fpara 'Unlike charges attract' (52, mint key word). Both rule lines now stacked in the text panel.","tts_text":"والقاعدة التانية: الـ unlike charges بتعمل attract، بتشِدّ بعض.","screen_text":"Unlike charges attract","pause_after_s":0.4},{"id":"s2l6","visual":"Callback to the anchor: the two hanging balloons, each with cyan '−' signs, swing apart on cue 'repel'; YK.tag 'like charges' between them on cue 'like'. Text panel YK.fpara 'Two balloons: like charges -> repel'.","tts_text":"عشان كده البالونتين بيعملوا repel، لأنهم like charges من نفس النوع.","screen_text":"Two balloons: like charges → repel","pause_after_s":0.3},{"id":"s2l7","visual":"Head + balloon shot: balloon with '−' signs, hair with '+' signs; hair bends to the balloon on cue 'attract'; YK.tag 'unlike charges' on cue 'unlike'. Text panel YK.fpara 'Balloon and hair: unlike charges -> attract'.","tts_text":"والبالونة والشَعر بيعملوا attract، لأنهم unlike charges، نوعين مختلفين.","screen_text":"Balloon and hair: unlike charges → attract","pause_after_s":0.4},{"id":"s2l8","visual":"Stage: a '+' sphere (x 1100) and a '−' sphere (x 1500), fixed distance; a strength bar under them (YK.roundRect 600×40 at (1000, 860), mint fill) labelled 'force' (YK.label 40) on cue 'force'. On cue 'يزيد' the '+' sphere grows (r 90→130) and its charge badge reads '+ +' (YK.atomDisc charge '2+'... drawn as two '+' labels); the bar fill rises 40%→80% on cue 'بتزيد'. Text panel YK.fpara 'More charge -> stronger force'.","tts_text":"وكل ما الـ charge يزيد، الـ force، يعني الشدّ أو الزقّ، بتزيد.","screen_text":"More charge → stronger force","pause_after_s":0.3},{"id":"s2l9","visual":"Same pair, normal size: the spheres move closer (gap 400→180) on cue 'يقرّبوا' while the bar fills to 90%; then apart (gap 180→520) on cue 'يبعدوا' while the bar drops to 25%. Text panel two lines: 'Closer -> stronger' (mint) on cue 'تقوى', 'Farther -> weaker' (textDim) on cue 'تضعف'.","tts_text":"وكل ما يقرّبوا من بعض الـ force تقوى، ولما يبعدوا تِضعف.","screen_text":"Closer → stronger · Farther → weaker","pause_after_s":0.4},{"id":"s2l10","visual":"Picture change: a zoom-in from a water drop (YK.drop) and a hair strand into a cluster of small grey discs (YK.atomDisc r 26, symbol:false, seeded jitter), YK.scaleBadge({exp:8}) in the stage corner on cue 'صغيرة'. YK.termCard({term:'atoms', def:'the tiny bits that things are made of'}) on cue 'atoms'.","tts_text":"المية والحديد وشَعرك نفسه متكونين من حبيبات صغيرة جدًا اسمها atoms، أو ذرات.","screen_text":"atoms: the tiny bits that things are made of","pause_after_s":0.4},{"id":"s2l11","visual":"One disc of the cluster grows into YK.atom(ctx, 1300, 580, {shells:[2,8,1], size:360, rotate:0.15*t, nucleusLabel:''}); the nucleus glows pink on cue 'nucleus'; YK.tag 'nucleus' on a leader line. YK.termCard({term:'nucleus', def:'the centre of the atom'}) on cue 'nucleus'.","tts_text":"في نص الـ atom فيه حتة صغيرة اسمها nucleus، يعني النواة.","screen_text":"nucleus: the centre of the atom","pause_after_s":0.3},{"id":"s2l12","visual":"Zoom bubble on the nucleus (YK.panel circle inset at (1640, 300), r 150) showing small pink '+' discs (YK.atomDisc r 22, label '+') on cue 'protons' (#0); YK.termCard({term:'protons', def:'in the nucleus, positive (+)'}) on the same cue; the '+' signs pulse on cue 'positive'.","tts_text":"جوه الـ nucleus فيه protons، والـ protons دي شايلة positive charge، علامتها زائد.","screen_text":"protons: in the nucleus, positive (+)","pause_after_s":0.3},{"id":"s2l13","visual":"The YK.atom electrons glow cyan on cue 'electrons' (colors.hl) and get small '−' labels; YK.termCard({term:'electrons', def:'around the nucleus, negative (−)'}) on cue 'electrons'.","tts_text":"وحوالين الـ nucleus بتتحرك electrons، شايلة negative charge، علامتها ناقص.","screen_text":"electrons: around the nucleus, negative (−)","pause_after_s":0.3},{"id":"s2l14","visual":"Short mint YK.arrow from each electron towards the nucleus on cue 'بيشد' (unlike charges). Text panel YK.fpara 'Nucleus (+) pulls electrons (−)'.","tts_text":"عشان كده الـ nucleus الـ positive بيشِدّ الـ electrons الـ negative ناحيته.","screen_text":"Nucleus (+) pulls electrons (−)","pause_after_s":0.3},{"id":"s2l15","visual":"YK.termCard({term:'nuclear attraction', def:'the nucleus pulls the electrons'}) on cue 'nuclear'; the inward mint arrows thicken and stay.","tts_text":"الشدّ ده الكتاب بيسميه nuclear attraction، يعني جذب النواة.","screen_text":"nuclear attraction","pause_after_s":0.4},{"id":"s2l16","visual":"YK.predictCard({kind:'PREDICT', q:'Two electrons in the same atom: attract or repel?', at:YK.cue('s2l16'), think:YK.cueEnd('s2l16'), end:YK.cue('s2l17')}): during the silence ONLY the question and the think ring; stage: two cyan '−' electrons of the atom highlighted with a gold YK.bracket each, no arrows.","tts_text":"توقّع: two electrons في نفس الـ atom، هيعملوا attract ولا repel؟ فكّر.","screen_text":"Predict: two electrons in the same atom: attract or repel?","pause_after_s":3},{"id":"s2l17","visual":"Myth beat: YK.mythLine({text:'Nothing happens: electrons are too small', wrongAt:YK.cueX('s2l17','غلط')}) coral at the top of the text panel + YK.wrongMark on cue 'غلط'; the ✕ stays for the whole visible time; the line exits 0.4 s after the line ends. Nothing struck through.","tts_text":"ناس ممكن تقول: مش هيحصل حاجة، عشان الـ electrons صغيرين أوي. ده غلط.","screen_text":"Nothing happens: electrons are too small","pause_after_s":0.3},{"id":"s2l18","visual":"Right model, bigger and held longer than the myth: the two highlighted electrons get coral outward YK.arrow pairs on cue 'repel' and drift slightly apart; YK.answerSlot({text:'Both negative -> like charges -> repel'}) + YK.rightMark on cue 'repel'.","tts_text":"الاتنين negative، يعني like charges، فبيعملوا repel وبيزقّوا بعض.","screen_text":"Both negative → like charges → repel ✓","pause_after_s":0.3},{"id":"s2l19","visual":"One electron dot zooms up (r 12→70) with a cyan '−' label on cue 'electron'; the '−' pulses on cue 'negative'. Text panel YK.fpara 'Size does not cancel charge' (mint, no strike, no ✕ on this negated sentence).","tts_text":"الحجم مش بيلغي الـ charge: الـ electron صغير، إنما شايل negative charge برضه.","screen_text":"Size does not cancel charge","pause_after_s":0.4},{"id":"s2l20","visual":"Back to the atom: coral outward arrows between neighbouring electrons; YK.termCard({term:'repulsion force', def:'electrons push each other apart'}) on cue 'repulsion'.","tts_text":"والزقّ ده بين الـ electrons الكتاب بيسميه repulsion force، قوة تنافُر.","screen_text":"repulsion force: electrons push each other apart","pause_after_s":0.4},{"id":"s2l21","visual":"Myth beat (the lesson's misconception): small static coral picture on the stage — the atom with inward arrows ONLY (repulsion arrows hidden) — and YK.mythLine({text:'Electrons feel the nucleus and nothing else', wrongAt:YK.cueX('s2l21','غلط')}) in coral; YK.wrongMark on both on cue 'غلط', ✕ held for their whole visible time; exits 0.4 s after the line.","tts_text":"فيه غلطة مشهورة: إن الـ electrons بتحِسّ بشدّ الـ nucleus لوحده. ده غلط.","screen_text":"Electrons feel the nucleus and nothing else","pause_after_s":0.3},{"id":"s2l22","visual":"Right model, larger and held longer: YK.tug(ctx, 1300, 580, 300, {pull:1, push:1, el:'', labels:{pull:'', push:''}, t}) style picture — mint inward arrows appear on cue 'بتتشد', coral outward arrows between electrons on cue 'بتزق' (both visible together); YK.rightMark on cue 'نفس'.","tts_text":"الصح إن الـ electrons بتتشِدّ ناحية الـ nucleus، وفي نفس الوقت بتزُقّ بعض.","screen_text":"✓ Pulled by the nucleus and pushing each other","pause_after_s":0.3},{"id":"s2l23","visual":"Same YK.tug picture, labels now on: labels:{pull:'nuclear attraction', push:'repulsion force'}; the pull label pulses mint on cue 'nuclear', the push label coral on cue 'repulsion'; text panel two lines 'nuclear attraction (in)' / 'repulsion force (out)'.","tts_text":"يعني nuclear attraction لجوه، و repulsion force لبره، الاتنين شغالين طول الوقت.","screen_text":"nuclear attraction (in) · repulsion force (out)","pause_after_s":0.4},{"id":"s2l24","visual":"Picture change: two nuclei side by side (YK.atomDisc pink, small '+' discs inside: 3 on the left, 6 on the right), one cyan electron each at the same distance (dashed equal-length guide lines); the right nucleus's inward mint arrow is thicker, drawn on cue 'أقوى'; YK.tag 'same distance' on the guides on cue 'ثابتة'.","tts_text":"لو المسافة ثابتة، protons أكتر في الـ nucleus يعني nuclear attraction أقوى.","screen_text":"Same distance: more protons → stronger nuclear attraction","pause_after_s":1},{"id":"s3l2","visual":"Stage: two nuclei (YK.atomDisc r 110, pink) labelled 'X' (x 1050) and 'Y' (x 1550) with YK.tag '11 protons' on cue 'eleven' and '17 protons' on cue 'seventeen'. Text panel: a 3-step checklist (YK.fpara rows 'Step 1' … 'Step 3', dim) and the line 'Atom X: 11 protons · Atom Y: 17 protons'.","tts_text":"عندنا atom إكس فيه eleven protons، و atom واي فيه seventeen كمان.","screen_text":"Atom X: 11 protons · Atom Y: 17 protons","pause_after_s":0.3},{"id":"s3l3","visual":"One cyan outer electron appears beside each nucleus on cue 'electrons', both at the same distance (dashed guide lines of equal length + YK.tag 'about the same distance' on cue 'المسافة').","tts_text":"والـ electrons اللي بره في الاتنين على نفس المسافة تقريبًا.","screen_text":"Outer electrons: about the same distance","pause_after_s":0.3},{"id":"s3l4","visual":"Question YK.fpara 'Which nucleus pulls its outer electrons more strongly?' (48, gold key 'more strongly') at the top of the text panel on cue 'السؤال'; a gold '?' path between the two nuclei.","tts_text":"السؤال: أنهي nucleus بيشِدّ الـ electrons اللي بره أقوى؟","screen_text":"Which nucleus pulls its outer electrons more strongly?","pause_after_s":0.4},{"id":"s3l5","visual":"Row 'Step 1: nucleus (+), electron (−) -> attract' turns bright on cue 'الأولى'; '+' labels on both nuclei on cue 'positive', '−' on both electrons on cue 'negative'; thin mint inward arrows on both sides on cue 'attract'.","tts_text":"الخطوة الأولى: الـ nucleus positive والـ electron negative، يعني فيه attract أكيد.","screen_text":"Step 1: nucleus (+), electron (−) → attract","pause_after_s":0.3},{"id":"s3l6","visual":"Row 'Step 2' bright on cue 'التانية'; the two equal dashed distance guides flash gold on cue 'المسافة'; both nuclei get a YK.bracket on cue 'charge'.","tts_text":"الخطوة التانية: المسافة زي بعض، فنقارن الـ charge اللي في الـ nucleus هنا وهناك.","screen_text":"Step 2: same distance → compare the charge","pause_after_s":0.3},{"id":"s3l7","visual":"Row 'Step 3' bright on cue 'التالتة'; the Y tag '17 protons' pulses gold on cue 'seventeen', the X tag '11 protons' dims on cue 'eleven'; nucleus Y grows slightly (r 110→130) on cue 'أكبر'.","tts_text":"الخطوة التالتة: seventeen protons أكتر من eleven، يعني charge أكبر.","screen_text":"Step 3: 17 protons > 11 protons → more charge","pause_after_s":0.3},{"id":"s3l8","visual":"Y's inward mint arrow thickens (width 8→18) on cue 'بيشد'; YK.answerSlot({text:'Y pulls more strongly'}) + YK.rightMark on cue 'أقوى'.","tts_text":"يبقى الـ nucleus بتاع واي هو اللي بيشِدّ أقوى.","screen_text":"Y pulls more strongly ✓","pause_after_s":0.3},{"id":"s3l9","visual":"Answer reason line YK.fpara 'Reason: more charge -> stronger nuclear attraction' under the answer slot; 'nuclear attraction' turns gold on cue 'nuclear'.","tts_text":"والسبب: charge أكبر على نفس المسافة، يعني nuclear attraction أقوى.","screen_text":"Reason: more charge → stronger nuclear attraction","pause_after_s":0.6},{"id":"s3l10","visual":"Picture change: the X/Y result shrinks to the top of the text panel as a model; stage: one pink nucleus (x 1150, y 580) with a cyan electron at short distance (x 1330) on cue 'قريب' and another far away (x 1720) on cue 'بعيد'; YK.tag 'near' / 'far' under them.","tts_text":"دورك: nucleus واحدة، وحواليها electron قريب منها و electron بعيد عنها.","screen_text":"Your turn: one nucleus, a near electron and a far electron","pause_after_s":0.3},{"id":"s3l11","visual":"YK.predictCard({kind:'QUICK CHECK', q:'Which electron is pulled more strongly?', at:YK.cue('s3l11'), think:YK.cueEnd('s3l11'), end:YK.cue('s3l12')}) with YK.checkPause ring through the whole pause; during the silence ONLY the question and the two electrons show (no arrows, no answer).","tts_text":"أنهي electron فيهم بيتشِدّ أقوى؟ وقّف الفيديو وفكّر، وبعدين كمّل.","screen_text":"Quick check: which electron is pulled more strongly?","pause_after_s":4},{"id":"s3l12","visual":"A thick mint inward arrow on the near electron, a thin one on the far electron, both on cue 'القريب'; YK.answerSlot({text:'The near electron'}) + YK.rightMark on cue 'أقوى'.","tts_text":"الإجابة: الـ electron القريب هو اللي بيتشِدّ أقوى.","screen_text":"The near electron ✓","pause_after_s":0.3},{"id":"s3l13","visual":"The two distance guides appear (short mint, long textDim) on cue 'المسافة'; reason line YK.fpara 'Reason: same charge, smaller distance -> stronger force' on cue 'السبب'.","tts_text":"والسبب: نفس الـ charge، إنما المسافة أصغر، فالـ force أقوى.","screen_text":"Reason: same charge, smaller distance → stronger force","pause_after_s":0.8},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":0.8},{"id":"s4l2","visual":"YK.chip(ctx, 820, 180, 'Structure of the atom', {kind:'concept', align:'left'}) (map title) on cue 'تركيب'; stage: the s2 atom (YK.atom, shells [2,8,1]) with '+' in the nucleus on cue 'protons' and '−' on the electrons on cue 'electrons'.","tts_text":"في الـ structure بتاع الـ atom، الـ protons positive والـ electrons عكسهم.","screen_text":"protons (+) · electrons (−)","pause_after_s":0.3},{"id":"s4l3","visual":"Stage: YK.tug(ctx, 1300, 600, 280, {pull:1, push:1, labels:{pull:'nuclear attraction', push:'repulsion force'}, t}) with the pull label pulsing on cue 'nuclear' and the push label on cue 'repulsion'.","tts_text":"في الفصل هتقارن الـ nuclear attraction لجوه، مع الـ repulsion force لبره.","screen_text":"nuclear attraction (in) vs repulsion force (out)","pause_after_s":0.3},{"id":"s4l4","visual":"YK.chip 'Atomic radius: nearly constant' (kind 'concept', map title; book Ch.1 pp.12-13) on cue 'chromium'; the YK.tug ring stays the same size (pull and push at 0.6); small YK.tag 'Cr' and 'Cu' at the ring's left and right on cues 'chromium' and 'copper'. No 3d term, no data here (taught in the chapter).","tts_text":"من الـ chromium لحد الـ copper، الـ atomic radius، يعني حجم الذرة، ثابت تقريبًا.","screen_text":"From chromium to copper: atomic radius nearly constant","pause_after_s":0.5},{"id":"s4l4b","visual":"Same shot (chip, Cr / Cu tags stay): the YK.tug ring stays the same size while both arrow sets grow together (pull and push 0.6→1 on cue 'الشد' / 'والزق').","tts_text":"والسبب إن الشدّ لجوه والزقّ لبره بيزيدوا الاتنين مع بعض.","screen_text":"Pull (in) and push (out) grow together","pause_after_s":0.5},{"id":"s4l5","visual":"Recap (≤ 20 s with s4l6–s4l7): YK.takeaway({title:'Electric charges attract and repel', line:'Like charges repel; unlike charges attract.', formula:'', t, pulse:[{word:'attract', at:YK.cueX('s4l5','attract')}, {word:'repel', at:YK.cueX('s4l5','repel')}]}) on cue 'الخلاصة'.","tts_text":"الخلاصة: الـ electric charges بتعمل attract وبتعمل repel، حسب نوعها.","screen_text":"Electric charges attract and repel","pause_after_s":0.3},{"id":"s4l6","visual":"Takeaway card stays; a small mint line under it 'More charge or less distance -> stronger force' fades in on cue 'charge'.","tts_text":"و charge أكبر أو مسافة أصغر، يعني force أقوى.","screen_text":"More charge or less distance → stronger force","pause_after_s":0.3},{"id":"s4l7","visual":"Voiced lock-in = the takeaway line 'Like charges repel; unlike charges attract.'; 'repel' pulses coral on cue 'repel', 'attract' mint on cue 'attract' and both stay; card held through the line + 1.5 s tail; last frame = the takeaway over the atom with inward and outward arrows (no fade to black).","tts_text":"الـ like charges بتعمل repel، والـ unlike charges بتعمل attract لبعض.","screen_text":"Like charges repel; unlike charges attract.","pause_after_s":1.5}],"logline":"هتعرف يعني إيه charge، وإمتى الـ charges بتعمل attract وإمتى repel، وإزاي ده بيحصل جوه الذرة بين الـ nucleus والـ electrons.","segments":[{"id":"s1","title":"Balloons that pull and 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تحُك بالونة في شَعرك شوية وبعدين\nابعدها بالراحة\nهتلاقي شَعرك بيقف ويتشِد ناحية البالونة من\nغير ما تلمسه\nولو حكّيت بالونتين وقرّبتهم من بعض هيزقّوا\nبعض بعيد\nاللي بيعمل كده حاجة اسمها electric charge\nيعني شُحنة كهربا\nوالـ charge نوعين positive وعلامته زائد و\nnegative وعلامته ناقص\nلما حكّيت البالونة البالونة والشَعر خدوا\ncharges مختلفة عن بعض\nولما حاجتين يشدّوا بعض لبعض بنقول إنهم\nبيعملوا attract يعني تجاذُب\nولما يزقّوا بعض بعيد بنقول إنهم بيعملوا\nrepel يعني تنافُر\nطب إمتى الـ charges تعمل attract وإمتى\nتعمل repel خلّينا نشوف\nلو الـ charges من نفس النوع بنسميهم like\ncharges يعني شحنات متشابهة\nوالقاعدة الأولى الـ like charges بتعمل\nrepel بتزُق بعض بعيد\nولو الـ charges مختلفة بنسميهم unlike\ncharges يعني شحنات مختلفة\nوالقاعدة التانية الـ unlike charges بتعمل\nattract بتشِد بعض\nعشان كده البالونتين بيعملوا repel لأنهم\nlike charges من نفس النوع\nوالبالونة والشَعر بيعملوا attract لأنهم\nunlike charges نوعين مختلفين\nوكل ما الـ charge يزيد الـ force يعني الشد\nأو الزق بتزيد\nوكل ما يقرّبوا من بعض الـ force تقوى ولما\nيبعدوا تِضعف\nالمية والحديد وشَعرك نفسه متكونين من\nحبيبات صغيرة جدًا اسمها atoms أو ذرات\nفي نص الـ atom فيه حتة صغيرة اسمها nucleus\nيعني النواة\nجوه الـ nucleus فيه protons والـ protons\nدي شايلة positive charge علامتها زائد\nوحوالين الـ nucleus بتتحرك electrons شايلة\nnegative charge علامتها ناقص\nعشان كده الـ nucleus الـ positive بيشِد\nالـ electrons الـ negative ناحيته\nالشد ده الكتاب بيسميه nuclear attraction\nيعني جذب النواة\nتوقّع two electrons في نفس الـ atom\nهيعملوا attract ولا repel فكّر\nناس ممكن تقول مش هيحصل حاجة عشان الـ\nelectrons صغيرين أوي ده غلط\nالاتنين negative يعني like charges\nفبيعملوا repel وبيزقّوا بعض\nالحجم مش بيلغي الـ charge الـ electron\nصغير إنما شايل negative charge برضه\nوالزق ده بين الـ electrons الكتاب بيسميه\nrepulsion force قوة تنافُر\nفيه غلطة مشهورة إن الـ electrons بتحِس بشد\nالـ nucleus لوحده ده غلط\nالصح إن الـ electrons بتتشِد ناحية الـ\nnucleus وفي نفس الوقت بتزُق بعض\nيعني nuclear attraction لجوه و repulsion\nforce لبره الاتنين شغالين طول الوقت\nلو المسافة ثابتة protons أكتر في الـ\nnucleus يعني nuclear attraction أقوى\nعندنا atom إكس فيه eleven protons و atom\nواي فيه seventeen كمان\nوالـ electrons اللي بره في الاتنين على نفس\nالمسافة تقريبًا\nالسؤال أنهي nucleus بيشِد الـ electrons\nاللي بره أقوى\nالخطوة الأولى الـ nucleus positive والـ\nelectron negative يعني فيه attract أكيد\nالخطوة التانية المسافة زي بعض فنقارن الـ\ncharge اللي في الـ nucleus هنا وهناك\nالخطوة التالتة seventeen protons أكتر من\neleven يعني charge أكبر\nيبقى الـ nucleus بتاع واي هو اللي بيشِد\nأقوى\nوالسبب charge أكبر على نفس المسافة يعني\nnuclear attraction أقوى\nدورك nucleus واحدة وحواليها electron قريب\nمنها و electron بعيد عنها\nأنهي electron فيهم بيتشِد أقوى وقّف\nالفيديو وفكّر وبعدين كمّل\nالإجابة الـ electron القريب هو اللي بيتشِد\nأقوى\nوالسبب نفس الـ charge إنما المسافة أصغر\nفالـ force أقوى\nطب الكلام ده هيفيدك فين في الفصل\nفي الـ structure بتاع الـ atom الـ protons\npositive والـ electrons عكسهم\nفي الفصل هتقارن الـ nuclear attraction\nلجوه مع الـ repulsion force لبره\nمن الـ chromium لحد الـ copper الـ atomic\nradius يعني حجم الذرة ثابت تقريبًا\nوالسبب إن الشد لجوه والزق لبره بيزيدوا\nالاتنين مع بعض\nالخلاصة الـ electric charges بتعمل attract\nوبتعمل repel حسب نوعها\nو charge أكبر أو مسافة أصغر يعني force\nأقوى\nالـ like charges بتعمل repel والـ unlike\ncharges بتعمل attract لبعض","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":65,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":140.28,"kind":"pause_question","spec":{"answer":"repel: الاتنين negative، يعني like charges، فبيزقّوا بعض.","prompt":"اتنين electrons في نفس الـ atom: هيعملوا attract ولا repel؟","options":[{"id":"a","text":"repel","correct":true},{"id":"b","text":"attract","correct":false},{"id":"c","text":"مش هيحصل حاجة، عشان الـ electrons صغيرين أوي","correct":false}],"answer_t_s":143.74,"concept_id":"phys.electric-charges"},"content_lang":"ar-EG"},{"id":"think-2","t_s":251.59,"kind":"pause_question","spec":{"answer":"الـ electron القريب: نفس الـ charge، والمسافة أصغر، فالـ force أقوى.","prompt":"nucleus واحدة، وحواليها electron قريب و electron بعيد: أنهي electron بيتشد أقوى؟","options":[{"id":"a","text":"الـ electron القريب","correct":true},{"id":"b","text":"الـ electron البعيد","correct":false},{"id":"c","text":"الاتنين بنفس القوة، عشان نفس الـ nucleus","correct":false}],"answer_t_s":256.14,"concept_id":"phys.electric-charges"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-phys.electric-charges"]},{"id":"chem-s3-en.video-walkthrough-sci.matter-particles","kind":"walkthrough","version":6,"ord":4,"content_lang":"ar-EG","primary_concept_id":"sci.matter-particles","concepts":[{"concept_id":"sci.matter-particles","role":"primary"}],"title":"Matter is made of atoms and molecules: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-sci.matter-particles v1 (s1 hook: gaps between steel rails, answer 'the metal gets longer when it gets hot'; s2 KeyTerm 'Atom' = 'The smallest building unit of matter that can take part in chemical reactions' (verbatim on the term card), bullets 'all matter is made of tiny particles; always moving, in a solid they vibrate in place; spaces between the particles', trap 'The particles of a solid do not move'; s3 KeyTerm 'Molecule' = 'The smallest part of a substance that can exist freely and has the properties of that substance' (verbatim), cards 'Molecule of an element' O2 / 'Molecule of a compound' H2O (2 H + 1 O), 'a metal such as iron is built from a huge number of iron atoms', trap 'A molecule must be made of different atoms'; s4 classify N2, Cl2 (element) / CO2, NH3, CO (compound) — N2 = worked example, CO2 = self-check; s5 recap 'heated rail particles vibrate more and need more space', 'count the kinds of atom'). Concept sci.matter-particles v2 (no recorded misconceptions: s2 refutes both lesson traps, s2l3-s2l4 and s2l18-s2l20). Book (Ch.1): metals as atoms in rows (iron/alloys section: 'Pure iron, as other metals, is formed of a crystal lattice of metal atoms arranged in compact closed rows'), p.13 'ions or atoms or molecules' (paramagnetic) — named in s4 without new terms (no lattice/alloy/ion/paramagnetic words). Dependents named in s4 (map titles as chips): atom.structure 'Structure of the atom', chem.elements-symbols 'Elements and their symbols', phys.states-melting-boiling 'States of matter, melting and boiling points'. Terms: s1 = matter, particles (2); s2 = vibrate, atom, chemical reactions (glossed), molecule, element, compound; s3/s4 none. 'Molecule of an element / of a compound' (4-word terms) are spoken as «molecule بتاع element / compound» to keep the ≤ 2 Latin words rule; screen_text shows 'element' / 'compound' and the lesson card titles appear as column chips (visual). Formulas spoken by name (water, oxygen, nitrogen, carbon dioxide), never letter by letter. Predicts: s2l2 (~1:00, 3 s) and s3l8 (~3:10, 4 s). Estimate: 46 lines, 487 narration words at ~2.4 w/s + 27 s pauses + joins = ~245 s (4.1 min); recap s4l7-s4l9 ~12 s. not-in-source: matter = anything that has mass and takes up space; iron, water and air are matter; particles too small to see; chemical reactions glossed as changes that give new substances; nitrogen is in air; CO2 is breathed out; O2 is the oxygen we breathe.","title":"Matter is made of atoms and molecules: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor on the stage: a railway track drawn in perspective (two steel-grey rails, YK.roundRect segments with a metallic gradient, wooden sleepers) from (820, 960) to the vanishing point (1500, 300); on cue 'فراغات' a small gap between two rail segments gets a gold YK.bracket and a zoom inset (YK.panel 360×240 at (1420, 640)) showing the gap. Text panel YK.fpara 'Railway tracks: small gaps between the rails' (44).","tts_text":"لو بصيت على قضبان القطر، هتلاقي فراغات صغيرة بين القضبان.","screen_text":"Railway tracks: small gaps between the rails","pause_after_s":0.4},{"id":"s1l3","visual":"Same shot; a big gold '?' path over the gap inset on cue 'ليه'; text panel YK.fpara 'Why leave gaps between the rails?' (48).","tts_text":"طب ليه يسيبوا الفراغات دي في قضبان صُلبة؟ خلّينا نفهم.","screen_text":"Why leave gaps between the rails?","pause_after_s":0.6},{"id":"s1l4","visual":"Picture change: three icons pop in left → right on the stage on their cues: a rail piece (YK.roundRect steel) on 'الحديد', a water drop YK.drop(ctx, 1300, 560, 70, {color:C.cyan}) on 'والمية', a soft air swirl (dashed cyan path) on 'والهوا'; YK.termCard({term:'matter', def:'anything that has mass and takes up space'}) on cue 'matter'.","tts_text":"الحديد والمية والهوا كلهم matter: أي حاجة ليها mass، يعني كتلة، وبتاخد مكان.","screen_text":"matter: anything that has mass and takes up space","pause_after_s":0.4},{"id":"s1l5","visual":"YK.termCard({term:'particles', def:'tiny pieces, too small to see'}) on cue 'particles'; the three icons each dissolve into a cloud of small dots (seeded YK.rng positions) on cue 'حبيبات'.","tts_text":"وأي matter متكونة من حبيبات صغيرة جدًا اسمها particles، مش بنشوفها بعينينا.","screen_text":"particles: tiny pieces, too small to see","pause_after_s":0.4},{"id":"s1l6","visual":"Zoom-through from the rail gap inset into a square grid of grey discs (YK.lattice(ctx, 1000, 260, 760, 600, {rows:5, cols:7, color:'#8FA3BF'})) on cue 'قرّبنا', YK.scaleBadge({exp:8}) in the stage corner; the grid is still (no motion yet). Text panel YK.fpara 'Zoom into the rail: tiny particles'.","tts_text":"لو قرّبنا جدًا جوه القضيب، هنلاقيه particles صغيرة جنب بعض.","screen_text":"Zoom into the rail: tiny particles","pause_after_s":0.4},{"id":"s1l7","visual":"The still lattice stays; two gold '?' paths: one over a disc on cue 'بتتحرك', one in a gap between discs on cue 'مسافات'. Text panel YK.fpara 'Do these particles move? Is there space between them?' (48).","tts_text":"السؤال: الـ particles دي بتتحرك ولا ثابتة؟ وبينها مسافات ولا لأ؟","screen_text":"Do these particles move? Is there space between them?","pause_after_s":1},{"id":"s2l2","visual":"YK.predictCard({kind:'PREDICT', q:'In a rail, do the particles move?', at:YK.cue('s2l2'), think:YK.cueEnd('s2l2'), end:YK.cue('s2l3')}); during the silence ONLY the question, the think ring and the still lattice (no motion).","tts_text":"توقّع: الـ particles جوه القضيب الصُلب بتتحرك ولا واقفة؟ فكّر.","screen_text":"Predict: in a rail, do the particles move?","pause_after_s":3},{"id":"s2l3","visual":"Myth beat (lesson trap s2): YK.mythLine({text:'The particles of the rail do not move', wrongAt:YK.cueX('s2l3','غلط')}) coral at the top of the text panel + YK.wrongMark on cue 'غلط', ✕ held for the whole visible time; the still lattice gets a coral outline for the same time; exits 0.4 s after the line. Nothing struck through.","tts_text":"ناس كتير بتقول واقفة خالص، عشان القضيب صُلب. ده غلط.","screen_text":"The particles of the rail do not move","pause_after_s":0.3},{"id":"s2l4","visual":"Right model, larger and held longer than the myth: the lattice discs start a small deterministic vibration (±8 px, YK.rng phase per disc, sin(t)) on cue 'بتتحرك' and keep it for the rest of the segment; YK.rightMark + YK.fpara '✓ Particles are always moving' (mint).","tts_text":"الصح: الـ particles بتتحرك على طول، حتى في الحاجات الصُلبة.","screen_text":"✓ Particles are always moving","pause_after_s":0.3},{"id":"s2l5","visual":"Short motion ticks around three discs on cue 'vibrate'; each disc's home position marked by a faint ring so the student sees it stays in place; YK.termCard({term:'vibrate', def:'move back and forth in place'}) on cue 'vibrate'.","tts_text":"في الحاجة الصُلبة زي القضيب، الـ particles بتعمل vibrate، يعني بتهتز مكانها.","screen_text":"Rail: particles vibrate in place","pause_after_s":0.3},{"id":"s2l6","visual":"A heat glow (YK.glowCircle C.heatRed) under the lattice on cue 'والحرارة'; the vibration amplitude grows (±8 → ±16 px) on cue 'أكتر' and the grid spacing widens slightly (the whole lattice gets 6% wider) on cue 'مساحة'.","tts_text":"والحرارة بتخلّيها تعمل vibrate أكتر، وكل واحدة تاخد مساحة أكبر.","screen_text":"Heat → they vibrate more and need more space","pause_after_s":0.3},{"id":"s2l7","visual":"Back to the anchor inset: the two rail segments lengthen and the gap narrows (gap 60 → 20 px) on cue 'بيطول'; mint YK.bracket on the narrowed gap on cue 'مكان'. Answers the s1 hook.","tts_text":"عشان كده القضيب السُخن بيطول شوية، والفراغات بتسيبله مكان.","screen_text":"Hot rail gets longer → the gap leaves room","pause_after_s":0.4},{"id":"s2l8","visual":"Vibrating lattice again: the gaps between discs glow mint (fill in the interstices) on cue 'مسافات'; YK.tag 'spaces' on one gap.","tts_text":"وكمان فيه مسافات فاضية بين الـ particles وبعض.","screen_text":"Spaces between the particles","pause_after_s":0.4},{"id":"s2l9","visual":"One disc of the lattice is outlined gold and pops forward as YK.atomDisc(ctx, 1300, 560, 110, {el:'Fe', symbol:false}) on cue 'atom'; YK.termCard({term:'atom', def:'the smallest building unit of matter …'}) on cue 'atom'.","tts_text":"أصغر وحدة بناء في الـ matter اسمها atom، يعني ذرة.","screen_text":"atom: the smallest building unit of matter","pause_after_s":0.3},{"id":"s2l10","visual":"The term card completes with the lesson definition verbatim: def 'the smallest building unit of matter that can take part in chemical reactions' (keys 'chemical reactions'); stage: two different atom discs meet and join (YK.flyer arcs) on cue 'chemical', a small sparkle path, then a new pair shape on cue 'جديدة'.","tts_text":"والـ atom يقدر يدخل في chemical reactions، يعني تفاعلات بتطلّع مواد جديدة.","screen_text":"… that can take part in chemical reactions","pause_after_s":0.4},{"id":"s2l11","visual":"Picture change: an iron bar outline (YK.roundRect steel) with its inside filled by many small YK.atomDisc({el:'Fe'}) discs (vibrating) on cue 'ضخم'; YK.tag 'iron atoms' on cue 'atoms'.","tts_text":"الـ iron متكون من عدد ضخم جدًا من الـ iron atoms دي.","screen_text":"iron: a huge number of iron atoms","pause_after_s":0.4},{"id":"s2l12","visual":"Two atom discs fly together (YK.flyer) and bond into YK.molecule(ctx, 1300, 560, {formula:'O2', r:70}) on cue 'molecule'; YK.termCard({term:'molecule', def:'atoms joined together'}) on cue 'molecule'.","tts_text":"وساعات الـ atoms بتلزق في بعض، وتعمل molecule، يعني جزيء.","screen_text":"molecule: atoms joined together","pause_after_s":0.3},{"id":"s2l12b","visual":"YK.termCard({term:'substance', def:'one particular kind of matter'}) on cue 'substance'; the H2O drop icon from s1l4 returns.","tts_text":"والـ substance يعني نوع واحد معيّن من المادة، زي المية كده.","screen_text":"substance: one particular kind of matter (e.g. water)","pause_after_s":0.3},{"id":"s2l13","visual":"The term card gets the lesson definition verbatim: def 'the smallest part of a substance that can exist freely and has the properties of that substance' (keys 'exist freely', 'properties'); stage: the molecule floats free (gentle drift) on cue 'لوحده'.","tts_text":"والـ molecule أصغر جزء من الـ substance، يقدر يعيش لوحده وليه خواصها.","screen_text":"molecule: the smallest part of a substance that can exist freely and has the properties of that substance","pause_after_s":0.4},{"id":"s2l14","visual":"YK.molecule(ctx, 1300, 560, {formula:'H2O', r:70}) builds on cues: two H discs on 'two', the O disc on 'one', bonds on 'لازقين'; formula label 'H2O' (YK.formula 56) and YK.tag '2 H + 1 O'.","tts_text":"زي الـ water: two hydrogen و one oxygen، لازقين في بعض.","screen_text":"H₂O (water): 2 H + 1 O","pause_after_s":0.3},{"id":"s2l15","visual":"Split stage: left YK.molecule O2 (both discs the same colour) on cue 'oxygen', right the H2O molecule moves over; YK.tag '2 atoms' under O2 on cue 'two', 'same kind' on cue 'النوع'.","tts_text":"والـ oxygen اللي بنتنفسه: two atoms من نفس النوع لازقين في بعض.","screen_text":"O₂ (oxygen): 2 atoms of the same kind","pause_after_s":0.3},{"id":"s2l16","visual":"Left column header YK.chip 'Molecule of an element' (kind 'concept', lesson card title) on cue 'element'; O2 sits under it; YK.termCard({term:'element', def:'its molecule: atoms of the same kind (O2)'}) in the text panel.","tts_text":"ولما الـ atoms من نوع واحد، يبقى ده molecule بتاع element، يعني عنصر.","screen_text":"Same kind of atom → element","pause_after_s":0.3},{"id":"s2l17","visual":"Right column header YK.chip 'Molecule of a compound' on cue 'compound'; H2O sits under it with its two colours pulsing on cue 'مختلفين'; YK.termCard({term:'compound', def:'its molecule: atoms of different kinds (H2O)'}).","tts_text":"أما الـ water فيه نوعين atoms مختلفين، فده molecule بتاع compound، يعني مركّب.","screen_text":"H₂O: different kinds of atom → compound","pause_after_s":0.4},{"id":"s2l18","visual":"Myth beat (lesson trap s3): YK.mythLine({text:'A molecule must be made of different atoms', wrongAt:YK.cueX('s2l18','غلط')}) coral + YK.wrongMark on cue 'غلط', ✕ held for its whole visible time; exits 0.4 s after the line.","tts_text":"فيه ناس فاكرة إن أي molecule لازم يكون atoms مختلفة. ده غلط.","screen_text":"A molecule must be made of different atoms","pause_after_s":0.3},{"id":"s2l19","visual":"Right model, larger and held longer: the O2 molecule scales up (r 70→100), both discs pulse on cue 'oxygen' (#1); YK.answerSlot({text:'O2 is a molecule with one kind of atom'}) + YK.rightMark on cue 'النوع'.","tts_text":"الـ oxygen ده molecule، والـ atoms بتاعته كلها oxygen، من نفس النوع.","screen_text":"O₂ is a molecule with one kind of atom ✓","pause_after_s":0.3},{"id":"s2l20","visual":"Rule line YK.fpara 'Count the kinds of atom, not the number of atoms' (mint key 'kinds', no strike, no ✕ on the negated part); under O2 a tag 'kinds: 1' appears on cue 'أنواع', under H2O 'kinds: 2' on the same cue.","tts_text":"يعني عُدّ أنواع الـ atoms، مش عدد الـ atoms، عشان تعرف.","screen_text":"Count the kinds of atom, not the number of atoms","pause_after_s":1},{"id":"s3l2","visual":"Stage: YK.molecule(ctx, 1300, 560, {formula:'N2', r:80}) on cue 'nitrogen'; two empty column headers 'element' / 'compound' (YK.tag) on cues 'element' and 'compound'. Text panel: 2-step checklist (YK.fpara rows 'Step 1', 'Step 2', dim) and the question line.","tts_text":"خلّينا نشوف الـ nitrogen اللي في الهوا: element ولا compound تفتكر؟","screen_text":"N₂ (nitrogen): element or compound?","pause_after_s":0.4},{"id":"s3l3","visual":"Row 'Step 1: count the atoms: 2' bright on cue 'الأولى'; each N disc gets a small count tag '1', '2' as it pulses; YK.tag '2' on cue 'two'.","tts_text":"الخطوة الأولى: نعِدّ الـ atoms، هنلاقي two بالظبط.","screen_text":"Step 1: count the atoms: 2","pause_after_s":0.3},{"id":"s3l4","visual":"Row 'Step 2' bright on cue 'التانية'; both discs flash the same colour on cue 'nitrogen'; YK.tag 'kinds: 1' on cue 'واحد'.","tts_text":"الخطوة التانية: نعِدّ الأنواع، الاتنين nitrogen، يعني نوع واحد.","screen_text":"Step 2: count the kinds: both nitrogen → 1 kind","pause_after_s":0.3},{"id":"s3l5","visual":"The N2 molecule slides under the 'element' header on cue 'element'; YK.answerSlot({text:'N2: 1 kind -> element'}) + YK.rightMark.","tts_text":"نوع واحد يبقى الـ nitrogen ده molecule بتاع element، عنصر.","screen_text":"1 kind → element ✓","pause_after_s":0.3},{"id":"s3l6","visual":"Reason line YK.fpara 'Reason: 2 atoms, but of the same kind' under the answer; the '2' tag dims and 'same kind' pulses gold on cue 'النوع'.","tts_text":"والسبب: صحيح فيه two atoms، إنما من نفس النوع.","screen_text":"Reason: 2 atoms, but of the same kind","pause_after_s":0.6},{"id":"s3l7","visual":"Picture change: the N2 result shrinks to the top of the text panel as a model; stage: YK.molecule(ctx, 1300, 560, {formula:'CO2', r:80}) on cue 'carbon'; the two headers stay empty.","tts_text":"دورك: الـ carbon dioxide اللي بنطلّعه في النفس.","screen_text":"Your turn: CO₂ (carbon dioxide)","pause_after_s":0.3},{"id":"s3l8","visual":"YK.predictCard({kind:'QUICK CHECK', q:'CO2: element or compound?', at:YK.cue('s3l8'), think:YK.cueEnd('s3l8'), end:YK.cue('s3l9')}) + YK.checkPause ring through the whole pause; during the silence ONLY the question and the molecule (no tags, no answer).","tts_text":"ده element ولا compound؟ وقّف الفيديو وفكّر، وبعدين كمّل.","screen_text":"Quick check: element or compound?","pause_after_s":4},{"id":"s3l9","visual":"CO2 slides under the 'compound' header on cue 'compound'; the C disc pulses on cue 'carbon', the O discs on cue 'oxygen'; YK.tag 'kinds: 2'; YK.answerSlot({text:'CO2: 2 kinds -> compound'}) + YK.rightMark.","tts_text":"الإجابة compound، لأن فيه نوعين atoms: carbon و oxygen، مختلفين.","screen_text":"CO₂: carbon + oxygen → 2 kinds → compound ✓","pause_after_s":0.3},{"id":"s3l10","visual":"Reason line YK.fpara 'Reason: count the kinds, not the atoms' (no strike); the N2 model and CO2 side by side with 'kinds: 1' and 'kinds: 2' tags pulsing on cue 'الأنواع' (#1).","tts_text":"والسبب: بنعِدّ الأنواع مش الـ atoms، والأنواع هنا مختلفة.","screen_text":"Reason: count the kinds, not the atoms","pause_after_s":0.8},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":0.8},{"id":"s4l2","visual":"YK.tag 'atom' on cue 'atom'; stage: one atom disc grows and turns see-through with a '?' path inside on cue 'جوه' (no parts drawn: taught next).","tts_text":"الدرس الجاي هيدخل جوه الـ atom، ويشوف هو متكون من إيه.","screen_text":"Next: inside the atom","pause_after_s":0.3},{"id":"s4l3","visual":"YK.tag 'elements' on cue 'elements'; stage: three atom discs of different colours (YK.atomDisc symbol:false) in a row on cue 'أنواع'.","tts_text":"وبعده درس الـ elements، هتعرف أسامي أنواع الـ atoms المختلفة.","screen_text":"Next: elements (kinds of atom)","pause_after_s":0.3},{"id":"s4l4","visual":"YK.tag 'matter' on cue 'matter'; the vibrating lattice from s2 with the heat glow (amplitude ±8 → ±16) on cue 'الحرارة'.","tts_text":"ولما تدرس حالات الـ matter، هتحتاج إن الحرارة بتخلّي الـ particles تتحرك أكتر.","screen_text":"Heat → particles move more","pause_after_s":0.3},{"id":"s4l5","visual":"YK.lattice(ctx, 1000, 260, 760, 560, {rows:5, cols:8, pack:'square', color:YK.atomColor('Fe')}) appears row by row on cue 'مرصوصة'; YK.tag 'book Ch.1' in the corner. No new terms written (no lattice/alloy labels).","tts_text":"وفي الفصل، هتشوف الـ iron نفسه atoms مرصوصة جنب بعض في صفوف.","screen_text":"Chapter 1: iron = iron atoms in rows","pause_after_s":0.3},{"id":"s4l6","visual":"Text panel: the phrase 'atoms or molecules' (YK.fpara 48, 'atoms' gold on cue 'atoms', 'molecules' violet on cue 'molecules'); stage: a single atom disc beside an O2 molecule.","tts_text":"والكتاب هيقول كتير atoms أو molecules، فلازم تفرّق بينهم.","screen_text":"Chapter 1: \"atoms or molecules\"","pause_after_s":0.5},{"id":"s4l7","visual":"Recap (≤ 20 s with s4l8–s4l9): YK.takeaway({title:'Matter is made of atoms and molecules', line:'Matter: moving particles with spaces between.', formula:'O2 · H2O', t, pulse:[{word:'atoms', at:YK.cueX('s4l7','atoms')}, {word:'molecules', at:YK.cueX('s4l7','molecules')}]}) on cue 'الخلاصة'.","tts_text":"الخلاصة: الـ matter متكونة من atoms و molecules، صغيرة جدًا.","screen_text":"Matter is made of atoms and molecules","pause_after_s":0.3},{"id":"s4l8","visual":"Takeaway card stays; its formula 'O2 · H2O' parts pulse in turn on cues 'oxygen' and 'مختلفة'.","tts_text":"الـ molecule: نوع واحد زي الـ oxygen، أو أنواع مختلفة زي الـ water مثلًا.","screen_text":"Molecule: one kind (O₂) or different kinds (H₂O)","pause_after_s":0.3},{"id":"s4l9","visual":"Voiced lock-in = the takeaway line 'Matter: moving particles with spaces between.'; 'moving' pulses gold on cue 'بتتحرك', 'spaces' on cue 'مسافات'; card held through the line + 1.5 s tail; last frame = the takeaway over the vibrating lattice (no fade to black).","tts_text":"يعني الـ matter: particles بتتحرك، وبينها مسافات.","screen_text":"Matter: moving particles with spaces between.","pause_after_s":1.5}],"logline":"هتعرف إن أي matter متكونة من particles بتتحرك وبينها مسافات، وتفرّق بين الـ atom والـ molecule، وبين molecule بتاع element و molecule بتاع compound.","segments":[{"id":"s1","title":"Gaps between the rails","concept_id":"sci.matter-particles"},{"id":"s2","title":"Moving particles, atoms and molecules","concept_id":"sci.matter-particles"},{"id":"s3","title":"Nitrogen: element or compound?","concept_id":"sci.matter-particles"},{"id":"s4","title":"Where Chapter 1 uses the particle 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بصيت على قضبان القطر هتلاقي فراغات\nصغيرة بين القضبان\nطب ليه يسيبوا الفراغات دي في قضبان صُلبة\nخلّينا نفهم\nالحديد والمية والهوا كلهم matter أي حاجة\nليها mass يعني كتلة وبتاخد مكان\nوأي matter متكونة من حبيبات صغيرة جدًا\nاسمها particles مش بنشوفها بعينينا\nلو قرّبنا جدًا جوه القضيب هنلاقيه\nparticles صغيرة جنب بعض\nالسؤال الـ particles دي بتتحرك ولا ثابتة\nوبينها مسافات ولا لأ\nتوقّع الـ particles جوه القضيب الصُلب\nبتتحرك ولا واقفة فكّر\nناس كتير بتقول واقفة خالص عشان القضيب صُلب\nده غلط\nالصح الـ particles بتتحرك على طول حتى في\nالحاجات الصُلبة\nفي الحاجة الصُلبة زي القضيب الـ particles\nبتعمل vibrate يعني بتهتز مكانها\nوالحرارة بتخلّيها تعمل vibrate أكتر وكل\nواحدة تاخد مساحة أكبر\nعشان كده القضيب السُخن بيطول شوية\nوالفراغات بتسيبله مكان\nوكمان فيه مسافات فاضية بين الـ particles\nوبعض\nأصغر وحدة بناء في الـ matter اسمها atom\nيعني ذرة\nوالـ atom يقدر يدخل في chemical reactions\nيعني تفاعلات بتطلّع مواد جديدة\nالـ iron متكون من عدد ضخم جدًا من الـ iron\natoms دي\nوساعات الـ atoms بتلزق في بعض وتعمل\nmolecule يعني جزيء\nوالـ substance يعني نوع واحد معيّن من\nالمادة زي المية كده\nوالـ molecule أصغر جزء من الـ substance\nيقدر يعيش لوحده وليه خواصها\nزي الـ water two hydrogen و one oxygen\nلازقين في بعض\nوالـ oxygen اللي بنتنفسه two atoms من نفس\nالنوع لازقين في بعض\nولما الـ atoms من نوع واحد يبقى ده\nmolecule بتاع element يعني عنصر\nأما الـ water فيه نوعين atoms مختلفين فده\nmolecule بتاع compound يعني مركّب\nفيه ناس فاكرة إن أي molecule لازم يكون\natoms مختلفة ده غلط\nالـ oxygen ده molecule والـ atoms بتاعته\nكلها oxygen من نفس النوع\nيعني عُد أنواع الـ atoms مش عدد الـ atoms\nعشان تعرف\nخلّينا نشوف الـ nitrogen اللي في الهوا\nelement ولا compound تفتكر\nالخطوة الأولى نعِد الـ atoms هنلاقي two\nبالظبط\nالخطوة التانية نعِد الأنواع الاتنين\nnitrogen يعني نوع واحد\nنوع واحد يبقى الـ nitrogen ده molecule\nبتاع element عنصر\nوالسبب صحيح فيه two atoms إنما من نفس\nالنوع\nدورك الـ carbon dioxide اللي بنطلّعه في\nالنفس\nده element ولا compound وقّف الفيديو وفكّر\nوبعدين كمّل\nالإجابة compound لأن فيه نوعين atoms\ncarbon و oxygen مختلفين\nوالسبب بنعِد الأنواع مش الـ atoms والأنواع\nهنا مختلفة\nطب الكلام ده هيفيدك فين في الفصل\nالدرس الجاي هيدخل جوه الـ atom ويشوف هو\nمتكون من إيه\nوبعده درس الـ elements هتعرف أسامي أنواع\nالـ atoms المختلفة\nولما تدرس حالات الـ matter هتحتاج إن\nالحرارة بتخلّي الـ particles تتحرك أكتر\nوفي الفصل هتشوف الـ iron نفسه atoms مرصوصة\nجنب بعض في صفوف\nوالكتاب هيقول كتير atoms أو molecules\nفلازم تفرّق بينهم\nالخلاصة الـ matter متكونة من atoms و\nmolecules صغيرة جدًا\nالـ molecule نوع واحد زي الـ oxygen أو\nأنواع مختلفة زي الـ water مثلًا\nيعني الـ matter particles بتتحرك وبينها\nمسافات","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":66,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":44.96,"kind":"pause_question","spec":{"answer":"بتتحرك: في القضيب الـ particles بتهتز في مكانها، ولما يسخن بتهتز أكتر.","prompt":"الـ particles جوه قضيب السكة الحديد الصلب: بتتحرك ولا واقفة؟","options":[{"id":"a","text":"بتتحرك (بتهتز في مكانها)","correct":true},{"id":"b","text":"واقفة خالص، عشان القضيب صلب","correct":false}],"answer_t_s":48.7,"concept_id":"sci.matter-particles"},"content_lang":"ar-EG"},{"id":"think-2","t_s":191.32,"kind":"pause_question","spec":{"answer":"compound: فيه نوعين atoms، carbon و oxygen. بنعد الأنواع، مش عدد الـ atoms.","prompt":"الـ CO₂ (carbon dioxide): element ولا compound؟","options":[{"id":"a","text":"compound","correct":true},{"id":"b","text":"element","correct":false}],"answer_t_s":196.21,"concept_id":"sci.matter-particles"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-sci.matter-particles"]},{"id":"chem-s3-en.video-walkthrough-atom.atomic-mass-number","kind":"walkthrough","version":6,"ord":6,"content_lang":"ar-EG","primary_concept_id":"atom.atomic-mass-number","concepts":[{"concept_id":"atom.atomic-mass-number","role":"primary"}],"title":"Atomic number and mass number: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-atom.atomic-mass-number v1 (s1 hook '_{26}Fe and cobalt 60: what do the 26 and the 60 count?' with recall 'nucleus holds protons (+) and neutrons (no charge), electrons (−) outside'; s2 KeyTerm 'Atomic number' = 'The number of protons in the nucleus of an atom.' (verbatim), 'in a neutral atom: number of electrons = number of protons', 'each element has its own atomic number: scandium 21, zinc 30', tip 'neutral atoms only'; s3 KeyTerm 'Mass number' = 'The sum of the numbers of protons and neutrons in the nucleus.' (verbatim), A = Z + N, N = A − Z, worked example ^{60}_{27}Co: 27 protons, 27 electrons, 60 − 27 = 33 neutrons (used as the s3 worked example), trap 'The mass number counts the electrons too' (correction: electrons are very light); s4 'change only the neutrons: the element is fixed by Z, only the mass number changes'; s5 fill-blank ^{58}_{28}Ni: 28 / 28 / 30 (used as the NEW-case self-check), copper 29 + 34 = 63; s6 recap + exam callout 'use the atomic number to count the electrons before writing an electronic configuration in Ch.1'). Concept atom.atomic-mass-number v2 (no recorded misconceptions: s2 refutes the lesson trap (s2l15-s2l16) and the hook's wrong option 'protons and neutrons together' (s2l17-s2l18)). Book Ch.1 p.4 first transition series Sc … Zn (named with atomic numbers 21 and 30 in s4); cobalt section 'Cobalt has twelve radioactive isotopes, cobalt 60 …' (s4 says 60 is its mass number, no 'isotope'/'radioactive' words). Dependents named in s4 (map titles as written chips): atom.energy-levels 'Main energy levels' (+ 'Writing electronic configurations'), atom.isotopes 'Isotopes and average atomic mass'; stoich.molar-mass not named. Terms: s1 = atoms, protons, neutrons (3; positive/neutral as plain descriptors); s2 = electrons, nucleus, atomic number (Z), element, neutral atom, mass number; s3/s4 none. Symbols: Z spoken «زد»; the letter A is not used on screen (its Egyptian name «إيه» = 'what'); notation ^{A}_{Z}X read as 'the top number / the bottom number'. Predicts: s2l12 (~2:10, 3 s) and s3l8 (~3:50, 5 s). Estimate: 48 lines, ~560 narration words at ~2.4 w/s + 29 s pauses + joins = ~280 s (4.7 min); recap s4l6-s4l8 ~15 s. not-in-source: an ID number identifies one person (anchor); atoms = tiny particles that things are made of; electrons move around the centre; element = one kind of atom; nickel 58 and cobalt 60 use the lesson's numbers.","title":"Atomic number and mass number: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor on the stage: an ID card drawn with YK.panel(ctx, 1000, 360, 640, 380, {accent:C.gold}): a grey silhouette (YK.bodyShape, small) on the left and a long number row drawn as gold dots on the right (no real digits, no Arabic); on cue 'رقم' the number row glows; on cue 'مين' a gold YK.bracket links the number to the silhouette. Text panel YK.fpara 'ID card: one number, one person' (44).","tts_text":"بطاقتك فيها رقم قومي، الرقم ده بيقول إنت مين بالظبط.","screen_text":"ID card: one number, one person","pause_after_s":0.4},{"id":"s1l3","visual":"Picture change: the ID card slides to the stage corner (small, kept as the anchor); big YK.formula '_{26}Fe' (mono 120) on cue 'iron' and the label 'cobalt 60' (YK.formula 72) on cue 'cobalt'; the numbers 26 and 60 pulse gold on cue 'الأرقام'; a gold '?' path between them.","tts_text":"والكتاب بيكتب أرقام جنب الـ iron والـ cobalt، الأرقام دي بتعِدّ إيه؟","screen_text":"₂₆Fe · cobalt 60: what do the numbers count?","pause_after_s":0.6},{"id":"s1l4","visual":"Zoom-through: a piece of iron (YK.roundRect steel) and a water drop (YK.drop) dissolve into clusters of small discs (YK.atomDisc r 24, symbol:false, seeded jitter) on cue 'حبيبات', YK.scaleBadge({exp:8}) in the stage corner; YK.termCard({term:'atoms', def:'the tiny bits that things are made of'}) on cue 'atoms'.","tts_text":"الحديد والمية وإنت نفسك، متكونين من حبيبات صغيرة جدًا اسمها atoms، ذرات.","screen_text":"atoms: the tiny bits that things are made of","pause_after_s":0.4},{"id":"s1l5","visual":"One disc grows into YK.atom(ctx, 1300, 580, {shells:[2,8,1], size:380, rotate:0.15*t, nucleusLabel:''}) with the electrons dimmed to 30%; the centre gets a gold YK.bracket on cue 'قلب'.","tts_text":"والـ atom ليه قلب صغير جدًا في النص.","screen_text":"The atom has a tiny centre","pause_after_s":0.3},{"id":"s1l6","visual":"Zoom inset on the centre (YK.panel circle at (1640, 300), r 160): pink discs (YK.atomDisc r 24, label '+') pop in on cue 'protons' (#0); YK.termCard({term:'protons', def:'in the centre, positive (+)'}) on the same cue; '+' signs pulse on cue 'positive'.","tts_text":"في القلب ده فيه protons، والـ protons دي شُحنتها positive، يعني موجبة.","screen_text":"protons: in the centre, positive (+)","pause_after_s":0.3},{"id":"s1l7","visual":"Grey discs (YK.atomDisc r 24, color:C.steel, no sign) join the pink ones in the inset on cue 'neutrons'; YK.termCard({term:'neutrons', def:'in the centre too, neutral (no charge)'}) on cue 'neutrons'; YK.tag 'neutral' on a grey disc on cue 'neutral'.","tts_text":"ومعاهم في القلب neutrons، ودي neutral، يعني ملهاش شُحنة.","screen_text":"neutrons: in the centre too, neutral","pause_after_s":0.4},{"id":"s1l8","visual":"Stage split: left the atom with its centre inset (pink + grey discs), right the formulas '_{26}Fe' and 'cobalt 60' with '26' and '60' gold; arrows with '?' from each number towards the centre on cues 'twenty-six' and 'sixty'. Text panel YK.fpara '26 and 60: what do they count?' (48).","tts_text":"طب الـ twenty-six والـ sixty دول، بيعدّوا إيه بالظبط؟","screen_text":"26 and 60: what do they count?","pause_after_s":1},{"id":"s2l2","visual":"The YK.atom electrons return to full brightness and glow cyan on cue 'electrons' with small '−' labels; YK.termCard({term:'electrons', def:'around the centre, negative (−)'}) on cue 'electrons'.","tts_text":"وحوالين القلب بتتحرك حاجات أصغر اسمها electrons، شُحنتها negative، يعني سالبة.","screen_text":"electrons: around the centre, negative (−)","pause_after_s":0.3},{"id":"s2l3","visual":"YK.termCard({term:'nucleus', def:'the centre of the atom: protons + neutrons'}) on cue 'nucleus'; YK.tag 'nucleus' on a leader line to the centre; inset pink and grey discs pulse on cues 'protons' and 'neutrons'.","tts_text":"والقلب ده اسمه nucleus، وفيه الـ protons والـ neutrons مع بعض.","screen_text":"nucleus: the centre (protons + neutrons)","pause_after_s":0.4},{"id":"s2l4","visual":"YK.termCard({term:'atomic number', def:'The number of protons in the nucleus of an atom.', keys:['protons']}) (lesson definition verbatim) on cue 'atomic'; in the inset ONLY the pink discs stay bright, grey discs dim to 30% (neutrons not counted).","tts_text":"عدد الـ protons في الـ nucleus اسمه atomic number، يعني العدد الذري.","screen_text":"atomic number: the number of protons in the nucleus of an atom","pause_after_s":0.3},{"id":"s2l5","visual":"Big YK.formula '_{26}Fe' (mono 140) centre-stage; on cue 'زد' a YK.tag 'Z' (and the term 'atomic number' pulses on cue 'atomic') appears beside the subscript; the '26' moves bottom-left emphasised with a gold YK.bracket on cue 'تحت'; formula '26' pulses on cue 'twenty-six'.","tts_text":"الـ atomic number رمزه زد، وبيتكتب تحت على الشمال: الـ iron تحته twenty-six مثلًا.","screen_text":"Z (atomic number), bottom left: ₂₆Fe → 26","pause_after_s":0.3},{"id":"s2l6","visual":"Inset nucleus of an iron atom: pink discs counted up with a tween counter tag that shows only the final '26 protons' (no intermediate numbers) on cue 'twenty-six'; grey discs present but dimmed.","tts_text":"يعني أي atom iron فيه twenty-six protons في الـ nucleus بتاعه.","screen_text":"₂₆Fe: 26 protons","pause_after_s":0.3},{"id":"s2l7","visual":"YK.termCard({term:'element', def:'one kind of atom; each element has its own atomic number'}) on cue 'element'; the ID card from s1 returns beside '_{26}Fe' and its number row glows together with the '26' on cue 'القومي' (anchor callback).","tts_text":"وكل نوع atom اسمه element، وليه atomic number خاص بيه، زي رقمك القومي.","screen_text":"element: one kind of atom · each element has its own atomic number","pause_after_s":0.3},{"id":"s2l8","visual":"Two element cards YK.elementCard-style (YK.panel + YK.formula): '_{21}Sc' 'Scandium' on cue 'scandium', '_{30}Zn' 'Zinc' on cue 'zinc'; '21' and '30' gold on cues 'twenty-one' and 'thirty'.","tts_text":"مثلًا الـ scandium رقمه twenty-one، والـ zinc رقمه thirty بالظبط.","screen_text":"Scandium: 21 · Zinc: 30","pause_after_s":0.4},{"id":"s2l9","visual":"YK.balance(ctx, 1300, 640, 600, {left:'protons (+)', right:'electrons (−)', value:0, leftColor:C.pink, rightColor:C.cyan}) appears on cue 'neutral' and settles level on cue 'بالظبط'; YK.termCard({term:'neutral atom', def:'electrons = protons'}).","tts_text":"والـ atom العادي، اللي اسمه neutral atom، الـ electrons فيه بعدد الـ protons بالظبط.","screen_text":"neutral atom: electrons = protons","pause_after_s":0.3},{"id":"s2l10","visual":"Balance pans labelled '26 protons (+)' on cue 'twenty-six' (#0) and '26 electrons (−)' on cue 'twenty-six' (#1); the beam stays level; formula '_{26}Fe' above.","tts_text":"فالـ iron فيه twenty-six protons، و twenty-six electrons كمان.","screen_text":"₂₆Fe: 26 protons → 26 electrons","pause_after_s":0.3},{"id":"s2l11","visual":"A small amber YK.tag 'Only in a neutral atom' pinned to the balance on cue 'neutral' (scoping the rule; no ions drawn here).","tts_text":"خلّي بالك: ده في الـ neutral atom، وهتشوف حالات تانية في الفصل.","screen_text":"Only in a neutral atom","pause_after_s":0.4},{"id":"s2l12","visual":"YK.predictCard({kind:'PREDICT', q:'cobalt 60: what does 60 count?', at:YK.cue('s2l12'), think:YK.cueEnd('s2l12'), end:YK.cue('s2l13')}); stage: a cobalt nucleus inset (pink + grey discs, no counts) and the label 'cobalt 60' with '60' gold; ONLY the question and ring during the silence.","tts_text":"توقّع: الـ sixty اللي في الـ cobalt sixty، بتعِدّ إيه؟ فكّر.","screen_text":"Predict: cobalt 60: what does 60 count?","pause_after_s":3},{"id":"s2l13","visual":"YK.termCard({term:'mass number', def:'The sum of the numbers of protons and neutrons in the nucleus.', keys:['protons','neutrons']}) (lesson definition verbatim) on cue 'mass'; in the inset BOTH pink and grey discs glow on cues 'protons' and 'neutrons'; '60' tag on the nucleus on cue 'sixty'.","tts_text":"الـ sixty هو الـ mass number: مجموع الـ protons والـ neutrons جوه الـ nucleus بتاعه.","screen_text":"mass number: the sum of the numbers of protons and neutrons in the nucleus","pause_after_s":0.3},{"id":"s2l14","visual":"Big YK.formula '^{60}_{27}Co' (mono 140); on cue 'mass' a YK.tag 'mass number' with a leader to the superscript; the '60' gets a gold YK.bracket on cue 'فوق' (#0); the '27' stays dim (explained in the example).","tts_text":"والـ mass number بيتكتب فوق على الشمال، زي الـ sixty فوق الـ cobalt هنا.","screen_text":"mass number: top left: ⁶⁰₂₇Co → 60","pause_after_s":0.4},{"id":"s2l15","visual":"Myth beat (lesson trap s3): YK.mythLine({text:'The mass number counts the electrons too', wrongAt:YK.cueX('s2l15','غلط')}) coral + a small coral picture of the atom with the electrons circled into the count; YK.wrongMark on both on cue 'غلط', ✕ held for their whole visible time; exits 0.4 s after the line. Nothing struck through.","tts_text":"ناس بتفتكر إن الـ mass number بيعِدّ الـ electrons كمان. ده غلط.","screen_text":"The mass number counts the electrons too","pause_after_s":0.3},{"id":"s2l16","visual":"Right model, larger and held longer: YK.balance with a tiny cyan electron dot on one pan vs a pink+grey nucleus cluster on the other (beam tips fully to the nucleus side) on cue 'خفيفة'; YK.rightMark + YK.fpara 'Electrons are very light -> not counted'.","tts_text":"الـ electrons خفيفة جدًا جنب الـ protons والـ neutrons، فمش بنعدّها.","screen_text":"Electrons are very light → not counted ✓","pause_after_s":0.3},{"id":"s2l17","visual":"Myth beat (hook option b): YK.mythLine({text:'26 in _{26}Fe = protons + neutrons', wrongAt:YK.cueX('s2l17','غلط')}) coral + YK.wrongMark on cue 'غلط', ✕ held for its whole visible time; exits 0.4 s after the line.","tts_text":"وكمان فيه غلطة: إن الـ twenty-six بتاعة الـ iron هي protons و neutrons. غلط.","screen_text":"₂₆Fe: 26 = protons + neutrons","pause_after_s":0.3},{"id":"s2l18","visual":"Right model, larger and held longer: '^{60}_{27}Co' with two leader tags: bottom number → 'protons' (pink) on cue 'تحت', top number → 'protons + neutrons' (pink + grey) on cue 'فوق'; YK.rightMark.","tts_text":"الرقم اللي تحت عدد الـ protons، واللي فوق protons و neutrons مع بعض.","screen_text":"Bottom number = protons · top number = protons + neutrons ✓","pause_after_s":0.4},{"id":"s2l19","visual":"YK.formula 'neutrons = mass number - atomic number' builds term by term on cues 'neutrons', 'atomic', 'mass'; in the inset the pink discs fade out of the cluster on cue 'اطرح', leaving the grey neutrons.","tts_text":"عشان تجيب الـ neutrons، اطرح الـ atomic number من الـ mass number اللي فوق.","screen_text":"neutrons = mass number − atomic number","pause_after_s":0.4},{"id":"s2l20","visual":"Lesson 'Build a nucleus' idea: the inset nucleus gains two grey discs (YK.flyer) on cue 'زادت' then loses them on cue 'قلّت'; the element label 'iron' stays fixed (gold outline) on cue 'element'; only the mass-number tag changes value (final values only, no counting animation) on cue 'يتغيّر'.","tts_text":"ولو الـ neutrons زادت أو قلّت، الـ element هو هو، والـ mass number يتغيّر.","screen_text":"More or fewer neutrons: same element, new mass number","pause_after_s":0.3},{"id":"s2l21","visual":"The ID card beside '_{26}Fe' again; the '26' and the card's number row glow together on cue 'القومي'; YK.fpara 'The atomic number fixes the element' (mint).","tts_text":"لأن الـ atomic number هو اللي بيحدد الـ element، زي رقمك القومي.","screen_text":"The atomic number fixes the element","pause_after_s":1},{"id":"s3l2","visual":"Stage: big YK.formula '^{60}_{27}Co' (mono 140) at (1300, 360) on cue 'cobalt'; three empty count slots under it labelled 'protons', 'electrons', 'neutrons' (YK.tag) on their cues. Text panel: 3-step checklist (YK.fpara rows 'Step 1' … 'Step 3', dim).","tts_text":"خلّينا نحِلّ الـ cobalt sixty: فيه كام protons وكام electrons وكام neutrons جواه؟","screen_text":"⁶⁰₂₇Co (cobalt 60): protons, electrons, neutrons?","pause_after_s":0.3},{"id":"s3l3","visual":"Row 'Step 1: bottom number 27 -> 27 protons' bright on cue 'الأولى'; the '27' gets a gold YK.bracket on cue 'تحت' and flies (YK.flyer) into the 'protons' slot on cue 'twenty-seven' (#1).","tts_text":"الخطوة الأولى: الرقم اللي تحت twenty-seven، يعني فيه twenty-seven protons جوه.","screen_text":"Step 1: bottom number 27 → 27 protons","pause_after_s":0.3},{"id":"s3l4","visual":"Row 'Step 2' bright on cue 'التانية'; a small level YK.balance glyph on cue 'neutral'; '27' fills the 'electrons' slot on cue 'twenty-seven'.","tts_text":"الخطوة التانية: الـ atom ده neutral، فالـ electrons كمان twenty-seven بالظبط.","screen_text":"Step 2: neutral atom → 27 electrons","pause_after_s":0.3},{"id":"s3l5","visual":"Row 'Step 3' bright on cue 'التالتة'; YK.formula '60 - 27 = 33' builds on cues 'sixty', 'twenty-seven', 'thirty-three'; '33' flies into the 'neutrons' slot.","tts_text":"الخطوة التالتة: الـ neutrons هي sixty minus twenty-seven equals thirty-three بالظبط.","screen_text":"Step 3: neutrons = 60 − 27 = 33","pause_after_s":0.3},{"id":"s3l6","visual":"YK.formula '27 + 33 = 60' under the slots; the '60' links back to the superscript with a gold arc path on cue 'sixty'; YK.rightMark on cue 'مظبوط'.","tts_text":"ونتأكد: twenty-seven plus thirty-three equals sixty، مظبوط.","screen_text":"Check: 27 + 33 = 60 ✓","pause_after_s":0.6},{"id":"s3l7","visual":"Picture change: the cobalt result shrinks to the top of the text panel as a model; stage: YK.formula '^{58}_{28}Ni' (mono 140) on cue 'nickel'; '58' gold on cue 'فوق', '28' gold on cue 'تحت'; three empty slots again.","tts_text":"دورك: الـ nickel، الرقم اللي فوق fifty-eight، واللي تحت twenty-eight كمان.","screen_text":"Your turn: ⁵⁸₂₈Ni (nickel)","pause_after_s":0.3},{"id":"s3l8","visual":"YK.predictCard({kind:'QUICK CHECK', q:'_{28}^{58}Ni: protons? electrons? neutrons?', at:YK.cue('s3l8'), think:YK.cueEnd('s3l8'), end:YK.cue('s3l9')}) + YK.checkPause ring through the whole pause; during the silence ONLY the question, the formula and the empty slots (no numbers fill).","tts_text":"احسب الـ protons والـ electrons والـ neutrons، وقّف الفيديو وفكّر شوية.","screen_text":"Quick check: protons? electrons? neutrons?","pause_after_s":5},{"id":"s3l9","visual":"'28' fills the 'protons' slot on cue 'twenty-eight' (#0) and the 'electrons' slot on cue 'twenty-eight' (#1); small level balance glyph on cue 'neutral'.","tts_text":"الإجابة: twenty-eight protons و twenty-eight electrons، عشان الـ atom ده neutral أصلًا.","screen_text":"28 protons · 28 electrons","pause_after_s":0.3},{"id":"s3l10","visual":"YK.formula '58 - 28 = 30' builds on cues; '30' fills the 'neutrons' slot; YK.answerSlot({text:'_{28}^{58}Ni: 28 protons, 28 electrons, 30 neutrons'}) + YK.rightMark on cue 'thirty'.","tts_text":"والـ neutrons هي fifty-eight minus twenty-eight equals thirty بالظبط.","screen_text":"neutrons = 58 − 28 = 30","pause_after_s":0.3},{"id":"s3l11","visual":"Reason line YK.fpara under the answer; leader arrows from the bottom number to the protons and electrons slots on cue 'تحت', from both numbers to the neutrons slot on cue 'وطرح'.","tts_text":"والسبب: اللي تحت بيدّيك الـ protons والـ electrons، وطرح الرقمين بيطلّع الـ neutrons بتوعه.","screen_text":"Reason: bottom number → protons and electrons; top − bottom → neutrons","pause_after_s":0.8},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":0.8},{"id":"s4l2","visual":"Stage: YK.atom(ctx, 1300, 600, {Z:26, size:340, reveal:YK.prog(t, cue 'هتوزّعها', +1.5)}) with a tag '26 electrons' on cue 'عدد'.","tts_text":"في الـ neutral atom، الـ atomic number بيقولك عدد الـ electrons اللي هتوزّعها.","screen_text":"Neutral atom: atomic number → how many electrons to arrange","pause_after_s":0.3},{"id":"s4l3","visual":"Stage: two nucleus insets side by side with the same pink count and different grey counts, both labelled 'iron' on cue 'element'.","tts_text":"وهتقابل atoms من نفس الـ element، إنما عدد الـ neutrons مختلف.","screen_text":"Same element, different numbers of neutrons","pause_after_s":0.3},{"id":"s4l4","visual":"YK.formula 'cobalt 60' with '60' gold and a leader tag 'mass number' on cue 'mass'; YK.tag 'book Ch.1' in the corner.","tts_text":"زي الـ cobalt sixty اللي في الكتاب، الـ sixty ده الـ mass number بتاعه.","screen_text":"Book: cobalt 60 → 60 = mass number","pause_after_s":0.3},{"id":"s4l5","visual":"A row of ten small element tiles (YK.panel + YK.formula) '_{21}Sc' … '_{30}Zn' (book p.4 order: Sc Ti V Cr Mn Fe Co Ni Cu Zn) slides in left → right from cue 'scandium' to cue 'zinc'; the subscripts 21 and 30 pulse gold on their cues.","tts_text":"وفي الفصل، العناصر من الـ scandium twenty-one لحد الـ zinc thirty كمان.","screen_text":"Chapter 1: ₂₁Sc … ₃₀Zn","pause_after_s":0.5},{"id":"s4l6","visual":"Recap (≤ 20 s with s4l7–s4l8): YK.takeaway({title:'Atomic number and mass number', line:'Atomic number = protons; mass number = protons + neutrons.', formula:'^{60}_{27}Co', t, pulse:[{word:'Atomic', at:YK.cueX('s4l6','atomic')}, {word:'mass', at:YK.cueX('s4l6','mass')}]}) on cue 'الخلاصة'.","tts_text":"الخلاصة: الـ atomic number والـ mass number رقمين مختلفين، لكل واحد معنى.","screen_text":"Atomic number and mass number","pause_after_s":0.3},{"id":"s4l7","visual":"Takeaway card stays; a small mint line under it 'Neutrons = mass number - atomic number' fades in on cue 'neutrons'.","tts_text":"والـ neutrons هي الـ mass number minus الـ atomic number، وخلاص.","screen_text":"Neutrons = mass number − atomic number","pause_after_s":0.3},{"id":"s4l8","visual":"Voiced lock-in = the takeaway line 'Atomic number = protons; mass number = protons + neutrons.'; 'Atomic number' pulses gold on cue 'atomic', 'mass number' on cue 'mass' and both stay; card held through the line + 1.5 s tail; last frame = the takeaway over the cobalt nucleus inset (no fade to black).","tts_text":"الـ atomic number يعني protons، والـ mass number يعني protons و neutrons سوا.","screen_text":"Atomic number = protons; mass number = protons + neutrons.","pause_after_s":1.5}],"logline":"هتعرف الرقمين اللي جنب أي element معناهم إيه، وتحسب منهم عدد الـ protons والـ electrons والـ neutrons في أي atom.","segments":[{"id":"s1","title":"An ID number for atoms","concept_id":"atom.atomic-mass-number"},{"id":"s2","title":"What the two numbers count","concept_id":"atom.atomic-mass-number"},{"id":"s3","title":"Counting the particles of cobalt 60","concept_id":"atom.atomic-mass-number"},{"id":"s4","title":"Where Chapter 1 uses the two 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فيها رقم قومي الرقم ده بيقول إنت\nمين بالظبط\nوالكتاب بيكتب أرقام جنب الـ iron والـ\ncobalt الأرقام دي بتعِد إيه\nالحديد والمية وإنت نفسك متكونين من حبيبات\nصغيرة جدًا اسمها atoms ذرات\nوالـ atom ليه قلب صغير جدًا في النص\nفي القلب ده فيه protons والـ protons دي\nشُحنتها positive يعني موجبة\nومعاهم في القلب neutrons ودي neutral يعني\nملهاش شُحنة\nطب الـ twenty-six والـ sixty دول بيعدّوا\nإيه بالظبط\nوحوالين القلب بتتحرك حاجات أصغر اسمها\nelectrons شُحنتها negative يعني سالبة\nوالقلب ده اسمه nucleus وفيه الـ protons\nوالـ neutrons مع بعض\nعدد الـ protons في الـ nucleus اسمه atomic\nnumber يعني العدد الذري\nالـ atomic number رمزه زد وبيتكتب تحت على\nالشمال الـ iron تحته twenty-six مثلًا\nيعني أي atom iron فيه twenty-six protons\nفي الـ nucleus بتاعه\nوكل نوع atom اسمه element وليه atomic\nnumber خاص بيه زي رقمك القومي\nمثلًا الـ scandium رقمه twenty-one والـ\nzinc رقمه thirty بالظبط\nوالـ atom العادي اللي اسمه neutral atom\nالـ electrons فيه بعدد الـ protons بالظبط\nفالـ iron فيه twenty-six protons و\ntwenty-six electrons كمان\nخلّي بالك ده في الـ neutral atom وهتشوف\nحالات تانية في الفصل\nتوقّع الـ sixty اللي في الـ cobalt sixty\nبتعِد إيه فكّر\nالـ sixty هو الـ mass number مجموع الـ\nprotons والـ neutrons جوه الـ nucleus\nبتاعه\nوالـ mass number بيتكتب فوق على الشمال زي\nالـ sixty فوق الـ cobalt هنا\nناس بتفتكر إن الـ mass number بيعِد الـ\nelectrons كمان ده غلط\nالـ electrons خفيفة جدًا جنب الـ protons\nوالـ neutrons فمش بنعدّها\nوكمان فيه غلطة إن الـ twenty-six بتاعة الـ\niron هي protons و neutrons غلط\nالرقم اللي تحت عدد الـ protons واللي فوق\nprotons و neutrons مع بعض\nعشان تجيب الـ neutrons اطرح الـ atomic\nnumber من الـ mass number اللي فوق\nولو الـ neutrons زادت أو قلّت الـ element\nهو هو والـ mass number يتغيّر\nلأن الـ atomic number هو اللي بيحدد الـ\nelement زي رقمك القومي\nخلّينا نحِل الـ cobalt sixty فيه كام\nprotons وكام electrons وكام neutrons جواه\nالخطوة الأولى الرقم اللي تحت twenty-seven\nيعني فيه twenty-seven protons جوه\nالخطوة التانية الـ atom ده neutral فالـ\nelectrons كمان twenty-seven بالظبط\nالخطوة التالتة الـ neutrons هي sixty minus\ntwenty-seven equals thirty-three بالظبط\nونتأكد twenty-seven plus thirty-three\nequals sixty مظبوط\nدورك الـ nickel الرقم اللي فوق fifty-eight\nواللي تحت twenty-eight كمان\nاحسب الـ protons والـ electrons والـ\nneutrons وقّف الفيديو وفكّر شوية\nالإجابة twenty-eight protons و\ntwenty-eight electrons عشان الـ atom ده\nneutral أصلًا\nوالـ neutrons هي fifty-eight minus\ntwenty-eight equals thirty بالظبط\nوالسبب اللي تحت بيدّيك الـ protons والـ\nelectrons وطرح الرقمين بيطلّع الـ neutrons\nبتوعه\nطب الكلام ده هيفيدك فين في الفصل\nفي الـ neutral atom الـ atomic number\nبيقولك عدد الـ electrons اللي هتوزّعها\nوهتقابل atoms من نفس الـ element إنما عدد\nالـ neutrons مختلف\nزي الـ cobalt sixty اللي في الكتاب الـ\nsixty ده الـ mass number بتاعه\nوفي الفصل العناصر من الـ scandium\ntwenty-one لحد الـ zinc thirty كمان\nالخلاصة الـ atomic number والـ mass number\nرقمين مختلفين لكل واحد معنى\nوالـ neutrons هي الـ mass number minus الـ\natomic number وخلاص\nالـ atomic number يعني protons والـ mass\nnumber يعني protons و neutrons سوا","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":67,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":104.49,"kind":"pause_question","spec":{"answer":"الـ 60 هو الـ mass number: مجموع الـ protons والـ neutrons في الـ nucleus.","prompt":"الـ 60 في cobalt 60 بتعدّ إيه؟","options":[{"id":"a","text":"الـ protons والـ neutrons مع بعض","correct":true},{"id":"b","text":"الـ protons لوحدها","correct":false},{"id":"c","text":"الـ protons والـ neutrons والـ electrons","correct":false}],"answer_t_s":108.2,"concept_id":"atom.atomic-mass-number"},"content_lang":"ar-EG"},{"id":"think-2","t_s":207.6,"kind":"pause_question","spec":{"answer":"الرقم اللي تحت 28: يعني 28 protons و 28 electrons (atom neutral)، والـ neutrons = 58 − 28 = 30.","prompt":"⁵⁸₂₈Ni (nickel): كام proton، وكام electron، وكام neutron؟","options":[{"id":"a","text":"28 protons، 28 electrons، 30 neutrons","correct":true},{"id":"b","text":"28 protons، 28 electrons، 58 neutrons","correct":false},{"id":"c","text":"30 protons، 30 electrons، 28 neutrons","correct":false}],"answer_t_s":213.09,"concept_id":"atom.atomic-mass-number"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-atom.atomic-mass-number"]},{"id":"chem-s3-en.video-walkthrough-atom.energy-levels","kind":"walkthrough","version":4,"ord":8,"content_lang":"ar-EG","primary_concept_id":"atom.energy-levels","concepts":[{"concept_id":"atom.energy-levels","role":"primary"}],"title":"Main energy levels: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-atom.energy-levels v4 (s1 hook calcium 20 electrons in 4 levels, MCQ M = 8/16/18/9; s2 KeyTerm 'Main energy levels' (book-style definition used verbatim on the term card), caption 'farther from the nucleus, the higher the energy', N_max = 2n^2 K to N: 2, 8, 18, 32; s3 interact Z 1-20 with M capped at 8 and the look card 'M can hold 18, but in potassium and calcium it has only 8; 19th and 20th electrons go to N; sublevels explain why (next lessons)', KeyTerm 'Valence electrons' scoped to main-group atoms Z = 1 to 20; s4 aluminum Z = 13 fill-blank 2, 8, 3 and 2, 8, 7 MCQ; s5 recap). Concept atom.energy-levels v2 (no recorded misconceptions: s2 refutes the lesson hook's wrong options 'M = 8 like L' and 'M = 16 doubling' (s2l11, ✕) with 2 × 3² = 18 (s2l12) and the reason 'the limit comes from n' (s2l13), and the look-card trap 'M is full at 8' (s2l19-s2l21)). Scope guards: 2n² stated for K to N only (rule absolutes-exceptions; s2l15, takeaway 'Levels K to N'); valence = outer electrons for main-group atoms only (rule pauli/valence; s2l23); level list and n values end with '…' (no hidden absolute). Dependents named in s4 (not in book, map titles): atom.sublevels 'Energy sublevels (s, p, d, f)' (chip shortened to 'Energy sublevels' so every shown word is spoken), chem.ions 'Ions (cations and anions)' (chip 'Ions'), pt.groups-periods 'Periodic table: periods and groups'; in-book link: book p.4 'the first transition series is located in the fourth period after calcium' (s4l5). No details of the dependents taught. Terms (defined at first use): s1 nucleus, electron, Main energy levels (3); s2 n (level number), 2n² rule, atomic number (Z), valence electrons. Worked example aluminum Z = 13 (lesson s4 data, spelling 'aluminum'); self-check NEW case potassium Z = 19 -> 2, 8, 8, 1, 1 valence electron (pause 4 s). Voicing: 2n² = «اتنين n تربيع»; level letters K, L, M, N spoken as Latin letters inside Arabic, separated by «و». Known line-rule exception: s1l7 says the three-word term 'main energy levels' once (3 Latin words in a row; no whitelist rule exists) — narrator: STT-check that line. not-in-source: stadium-rows analogy (s1l2-s1l8, analogy only); 'n² = n × n, 3² = 9' (arithmetic). Estimated duration ≈ 5.1 min (628 words at ~2.4 words/s + 33 s of pauses).","title":"Main energy levels: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor, stage x 790–1824: top view of a stadium drawn with ctx paths: a C.panel pitch rectangle (r 20) at (1300, 580) and four concentric rounded-rect seat rows around it (C.steel strokes, lw 6) that draw outward one by one from cue YK.cueX('s1l2','المدرجات') to YK.cueX('s1l2','صف',1). Text panel: YK.fpara 'A stadium: rows of seats around the pitch' (44).","tts_text":"تخيّل ملعب كورة: المدرجات حوالين الملعب، صف ورا صف.","screen_text":"A stadium: rows of seats around the pitch","pause_after_s":0.4},{"id":"s1l3","visual":"Seat dots (C.cyan, r 8) fill the rows: inner row gets few dots on cue YK.cueX('s1l3','صغير'), the outer rows get many more on cue 'أكبر' (dot counts grow outward; no numbers drawn). YK.bracket around the inner row then the outer row on the same cues. Text panel YK.fpara 'Close rows: fewer seats · far rows: more seats' (40).","tts_text":"الصف اللي قريب من الملعب صغير، واللي بعيد أكبر وبياخد ناس أكتر.","screen_text":"Close rows: fewer seats · far rows: more seats","pause_after_s":0.4},{"id":"s1l4","visual":"Picture change: the stadium shrinks to a corner card (YK.panel 1500, 160, 300, 200) and stays as the anchor. Stage: YK.atom(ctx, 1300, 600, {shells:[], nucleusLabel:'', size:360}) = a lone pink nucleus that pulses on cue YK.cueX('s1l4','nucleus'). Text panel: YK.termCard(ctx, 96, 300, {term:'nucleus', def:'the centre of the atom', align:'left'}) on cue 'nucleus'; a dashed leader line from the pitch in the corner card to the nucleus on cue 'الملعب'.","tts_text":"الذرة كمان ليها مركز في النص، اسمه الـ nucleus، زي الملعب كده.","screen_text":"nucleus: the centre of the atom","pause_after_s":0.4},{"id":"s1l5","visual":"Stage: cyan electron dots (r 12) swarm loosely around the nucleus (deterministic YK.rng(7) offsets, slow drift with t), appearing on cue YK.cueX('s1l5','جسيمات'); each dot shows a tiny '−' on cue 'سالبة'. Text panel: YK.termCard(ctx, 96, 300, {term:'electron', def:'a tiny particle with a negative charge that moves around the nucleus', keys:['negative charge'], align:'left'}) on cue 'electrons'; the corner stadium card's seat dots glow on cue 'الجمهور'.","tts_text":"وحوالين الـ nucleus بتتحرك جسيمات صغيرة سالبة اسمها electrons، زي الجمهور.","screen_text":"electron: a tiny particle with a negative charge that moves around the nucleus","pause_after_s":0.4},{"id":"s1l6","visual":"The swarm grows to exactly 20 dots on cue YK.cueX('s1l6','twenty'); nucleus label 'Ca' appears on cue 'calcium'. Text panel: YK.formula 'Calcium: 20 electrons' (mono 48), '20' gold on cue 'twenty'.","tts_text":"الـ calcium مثلًا فيه twenty electrons بيتحركوا حوالين الـ nucleus بتاعه.","screen_text":"Calcium: 20 electrons around the nucleus","pause_after_s":0.4},{"id":"s1l7","visual":"Picture change: the 20 dots snap into four rings: YK.atom(ctx, 1300, 600, {shells:[2,8,8,2], nucleusLabel:'Ca', size:400, reveal:YK.prog(t, YK.cueX('s1l7','مناطق'), YK.cueX('s1l7','main')), rotate:t}); rings drawn dashed (imaginary regions). Text panel: YK.termCard(ctx, 96, 260, {term:'Main energy levels', def:'Imaginary regions around the nucleus in which the electrons move according to their energy.', keys:['imaginary regions'], align:'left'}) on cue 'main'.","tts_text":"الـ electrons دي بتتحرك في مناطق حوالين الـ nucleus اسمها main energy levels، مستويات.","screen_text":"Main energy levels: imaginary regions around the nucleus in which the electrons move according to their energy","pause_after_s":0.5},{"id":"s1l8","visual":"Split stage: corner stadium card grows back to the left half of the stage (x 800–1280), the atom on the right half (x 1340–1800); on cue YK.cueX('s1l8','الجمهور') fans and electrons glow cyan together; on cue 'صفوف' rows and rings glow gold together (YK.bracket on one row + one ring). Text panel YK.fpara 'electrons ↔ fans · levels ↔ rows of seats' (40; ↔ drawn as a path).","tts_text":"يعني الـ electrons زي الجمهور، والـ levels زي صفوف المدرجات حوالين الملعب.","screen_text":"electrons ↔ fans · levels ↔ rows of seats","pause_after_s":0.4},{"id":"s1l9","visual":"Stadium card exits; the atom alone, its rings empty and the 20 dots hovering above it (YK.rng(7) positions); a big gold '?' path over the outer ring on cue YK.cueX('s1l9','كام'). Text panel YK.fpara 'How many electrons can one level hold?' (48).","tts_text":"السؤال بقى: الـ level يقدر يشيل كام electron بالكتير؟","screen_text":"How many electrons can one level hold?","pause_after_s":1},{"id":"s2l2","visual":"Stage: YK.atom(ctx, 1300, 600, {shells:[0,0,0,0], nucleusLabel:'', size:420}) empty rings; a YK.tag on each ring pops on its spoken letter: 'K' on YK.cueX('s2l2','K'), 'L', 'M', 'N' on their cues; a faint dashed fifth ring with tag '…' on cue 'وكده' (more levels exist). Text panel YK.formula 'K, L, M, N, …' (mono 56).","tts_text":"من جوه لبرّه، أسماء الـ levels: K و L و M و N، وكده.","screen_text":"K, L, M, N, …","pause_after_s":0.4},{"id":"s2l3","visual":"Same rings; under each letter tag a second YK.tag 'n = 1' … 'n = 4' (formula) appears on cues 'one', 'two', 'three', 'four'; the faint fifth ring gets 'n = …' on cue 'وكده'. Text panel YK.formula 'n = 1, 2, 3, 4, …' (mono 56).","tts_text":"ورقم الـ level بنسميه n: one، two، three، four، وكده.","screen_text":"Level number n = 1, 2, 3, 4, …","pause_after_s":0.4},{"id":"s2l4","visual":"A vertical gold arrow path from the nucleus outward across the rings, drawn on cue YK.cueX('s2l4','أبعد'); the rings tint from C.steel (K) to C.gold (N) on cue 'energy'; YK.tag 'higher energy' at the arrow head on cue 'أعلى'. Text panel YK.fpara 'Farther from the nucleus → higher energy' (44, arrow as path).","tts_text":"والـ level اللي أبعد عن الـ nucleus، الـ energy بتاعته أعلى.","screen_text":"Farther from the nucleus → higher energy","pause_after_s":0.4},{"id":"s2l5","visual":"Callback to the anchor: a small stadium card (YK.panel 1560, 160, 260, 180) beside the atom, its outer row glows on cue YK.cueX('s2l5','المدرجات'); on cue 'أكتر' the rings of the atom widen slightly outward (stroke lw 4→8 from K to N). No numbers yet.","tts_text":"وزي المدرجات، الـ level اللي أبعد بيشيل electrons أكتر.","screen_text":"Farther level → room for more electrons","pause_after_s":0.4},{"id":"s2l6","visual":"Picture change: text panel YK.termCard(ctx, 96, 260, {term:'2n^2', formula:true, def:'maximum number of electrons in level n', align:'left'}) on cue YK.cueX('s2l6','القاعدة'); stage: big YK.formula 'N_{max} = 2n^2' (mono 120) centred at (1300, 380), '2' pulses on cue 'two', 'n^2' on cue 'squared'. The empty atom moves down (y 760, 60%).","tts_text":"والقاعدة: أقصى عدد electrons في الـ level هو two n squared بالظبط.","screen_text":"Maximum number of electrons in level n = 2n²","pause_after_s":0.4},{"id":"s2l7","visual":"Under the big formula: YK.formula 'n^2 = n × n' (mono 64) on cue YK.cueX('s2l7','times'), then '3^2 = 3 × 3 = 9' builds on cues 'three' (#0), 'three' (#1), 'nine'; beside it a 3 × 3 grid of small squares (ctx rects) fills row by row on the same cues (9 squares). × drawn as a path (formula trap).","tts_text":"يعني n squared هي n times n: three times three equals nine بالظبط.","screen_text":"n² = n × n · 3² = 3 × 3 = 9","pause_after_s":0.5},{"id":"s2l8","visual":"Picture change: a 4-row table builds in the text panel (YK.formula rows, mono 48, one per line s2l8–s2l14): row 'K (n = 1): 2 × 1^2 = 2' on cue YK.cueX('s2l8','K'); stage: the atom (back to full size at 1300, 600) ring K glows and fills with 2 cyan dots (YK.flyer) on cue 'electrons'; tag '2' on ring K.","tts_text":"الـ K رقمه one: two times one squared equals two، يعني two electrons بالكتير.","screen_text":"K (n = 1): 2 × 1² = 2","pause_after_s":0.3},{"id":"s2l9","visual":"Row 'L (n = 2): 2 × 2^2 = 2 × 4 = 8' builds on cues 'L', 'four', 'eight'; ring L glows and fills with 8 dots on cue 'eight' (shown full only; no intermediate count); tag '8' on ring L.","tts_text":"والـ L رقمه two: two times four equals eight، يعني eight electrons بالكتير.","screen_text":"L (n = 2): 2 × 2² = 2 × 4 = 8","pause_after_s":0.3},{"id":"s2l10","visual":"YK.predictCard(ctx, t, {kind:'PREDICT', q:'The M level holds at most 8, 16 or 18?', at:YK.cue('s2l10'), until:YK.cue('s2l11'), think:YK.cueEnd('s2l10'), end:YK.cue('s2l11')}) over the text panel (table dimmed 35%); stage: ring M glows with a gold '?' tag; during the silence only the question and the think ring move.","tts_text":"توقّع: الـ M level بيشيل eight، ولا sixteen، ولا eighteen بالكتير؟","screen_text":"Predict: the M level holds at most 8, 16 or 18?","pause_after_s":3},{"id":"s2l11","visual":"Myth beat (lesson hook wrong options a and c): YK.mythLine(ctx, t, {at:YK.cue('s2l11'), wrongAt:YK.cueX('s2l11','غلط'), until:YK.cueEnd('s2l11')+0.4, text:'M = 8, like L? · M = 16, double 8?', x:96, y:300, size:48}) in coral; YK.wrongMark on cue 'غلط', held for the myth's whole visible time; nothing struck through; exits 0.4 s after the line.","tts_text":"ناس كتير بتقول eight زي الـ L، أو sixteen بالضعف. ده غلط.","screen_text":"M = 8, like L? · M = 16, double 8?","pause_after_s":0.3},{"id":"s2l12","visual":"Right model, larger and held longer than the myth (stays in the table until s2l15): row 'M (n = 3): 2 × 3^2 = 2 × 9 = 18' builds on cues 'three', 'nine', 'eighteen'; YK.rightMark beside it on cue 'eighteen'; ring M gets the tag '18' (no dots: capacity only).","tts_text":"نحسبها بالقاعدة: الـ M رقمه three، two times nine equals eighteen بالظبط.","screen_text":"M (n = 3): 2 × 3² = 2 × 9 = 18 ✓","pause_after_s":0.4},{"id":"s2l13","visual":"YK.bracket around the 'n = 3' part of the M row on cue YK.cueX('s2l13','رقم'); a short coral dashed arc from the L row to the M row fades (no ✕ on this negated sentence, no strike); text panel YK.fpara 'The limit comes from n, not from the level before' (40, textDim) under the table.","tts_text":"يعني السعة جاية من رقم الـ level، مش من الـ level اللي قبله.","screen_text":"The limit comes from n, not from the level before","pause_after_s":0.4},{"id":"s2l14","visual":"Row 'N (n = 4): 2 × 4^2 = 2 × 16 = 32' builds on cues 'N', 'sixteen', 'تلاتين'; ring N gets the tag '32'. The four tags 2, 8, 18, 32 now sit on the rings (stadium idea: farther = bigger).","tts_text":"والـ N رقمه four: two times sixteen equals thirty-two كمان.","screen_text":"N (n = 4): 2 × 4² = 2 × 16 = 32","pause_after_s":0.4},{"id":"s2l15","visual":"YK.bracket around the four rows of the table on cue YK.cueX('s2l15','four'); the faint fifth ring (n = …) stays without a number; YK.tag 'K to N (n = 1 to 4)' (gold) under the table on cue 'تحديدًا'.","tts_text":"خلّي بالك: القاعدة دي لأول four levels، من الـ K لحد الـ N تحديدًا.","screen_text":"The 2n² rule: the first four levels, K to N (n = 1 to 4)","pause_after_s":0.6},{"id":"s2l16","visual":"Picture change: table collapses to a chip 'K 2 · L 8 · M 18 · N 32' (YK.chip kind stable, 96, 150). Text panel YK.termCard(ctx, 96, 300, {term:'atomic number (Z)', def:'in a neutral atom, Z = number of electrons', align:'left'}) on cue YK.cueX('s2l16','atomic'). Stage: a simple element tile (YK.panel 1000, 300, 260, 260) with 'Z' in the corner pulsing on cue 'Z' and electron dots appearing beside it on cue 'electrons'.","tts_text":"الـ atomic number أو Z، هو عدد الـ electrons في الذرة الـ neutral، المتعادلة.","screen_text":"Neutral atom: atomic number (Z) = number of electrons","pause_after_s":0.4},{"id":"s2l17","visual":"Stage: YK.atom(ctx, 1300, 600, {Z:18, nucleusLabel:'Ar', size:400, reveal:YK.prog(t, YK.cueX('s2l17','K'), YK.cueX('s2l17','M')+0.6)}): rings fill inside → outward, K on cue 'K', L on cue 'L', M on cue 'M' (only full states drawn: 2, 8, 8). Text panel YK.formula 'Ar (Z = 18): 2, 8, 8' (mono 48).","tts_text":"لحد الـ argon: الأول الـ K، بعدين الـ L، بعدين الـ M كمان.","screen_text":"Up to argon (Z = 18): K first, then L, then M","pause_after_s":0.4},{"id":"s2l18","visual":"YK.atom(ctx, 1300, 600, {shells:[2,8,8,2], nucleusLabel:'Ca', size:400}) replaces Ar on cue YK.cueX('s2l18','calcium'); the shell counts light one by one on the spoken numbers (tags '2', '8', '8', '2'); ring N glows on cue 'N'. Text panel YK.formula 'Ca (Z = 20): 2, 8, 8, 2' (mono 48).","tts_text":"الـ calcium فيه twenty: two و eight و eight، و two في الـ N برّه.","screen_text":"Calcium (Z = 20): 2, 8, 8, 2","pause_after_s":0.4},{"id":"s2l19","visual":"Myth beat 2: YK.mythLine(ctx, t, {at:YK.cue('s2l19'), wrongAt:YK.cueX('s2l19','غلط'), until:YK.cueEnd('s2l19')+0.4, text:'M is full at 8?', x:96, y:300}) coral + YK.wrongMark on cue 'غلط', held for its whole visible time; ring M flashes coral for the same time. Nothing struck through.","tts_text":"ناس بتفتكر إن الـ M اتملى عند eight. ده غلط.","screen_text":"M is full at 8?","pause_after_s":0.3},{"id":"s2l20","visual":"Right model held longer than the myth: ring M drawn as 18 seat slots (ctx small circles along the ring), 8 of them filled cyan and 10 empty, on cue YK.cueX('s2l20','eight'); YK.tag '8 of 18' on ring M; YK.rightMark on cue 'مكان'. Text panel YK.fpara 'M can hold 18; in calcium it has 8' (44).","tts_text":"الـ M يقدر يشيل eighteen، وفي الـ calcium فيه eight، ولسه فيه مكان.","screen_text":"M can hold 18; in calcium it has 8 ✓","pause_after_s":0.4},{"id":"s2l21","visual":"The two N electrons of Ca pulse gold on cues 'nineteen' and 'عشرين' with tags '19' and '20'; a small YK.chip(ctx, 96, 760, 'a later lesson', {kind:'concept', align:'left'}) on cue 'درس'. No sublevel drawn.","tts_text":"وليه electron nineteen و twenty بيروحوا الـ N؟ ده في درس جاي.","screen_text":"Electrons 19 and 20 → N: why? (a later lesson)","pause_after_s":0.5},{"id":"s2l22","visual":"Picture change: Ca atom, ring N highlighted (highlightShell:3) on cue YK.cueX('s2l22','برّه'); its 2 dots glow gold on cue 'two' with YK.tag 'Ca: 2' (gold). Text panel YK.termCard(ctx, 96, 280, {term:'valence electrons', def:'the electrons in the outermost energy level', keys:['outermost'], align:'left'}) on cue 'valence'.","tts_text":"اللي في آخر energy level من برّه اسمهم valence electrons، زي الـ two دول.","screen_text":"valence electrons: the electrons in the outermost energy level","pause_after_s":0.4},{"id":"s2l23","visual":"YK.tag 'main-group atoms (Z = 1 to 20)' (40, textDim) under the term card on cue YK.cueX('s2l23','main'); stage unchanged except a slow rotate of the Ca atom (picture alive).","tts_text":"ده في ذرات الـ main-group، زي اللي معانا في الدرس ده.","screen_text":"For main-group atoms (here Z = 1 to 20)","pause_after_s":0.6},{"id":"s3l2","visual":"Stage: empty rings YK.atom(ctx, 1300, 600, {shells:[0,0,0], nucleusLabel:'Al', size:380}) on cue YK.cueX('s3l2','aluminum'); 13 cyan dots in a waiting cloud above it on cue 'thirteen'. Text panel: 4-step checklist (YK.fpara rows 'Step 1' … 'Step 4', dim) under YK.formula 'Aluminum (Z = 13): K ?, L ?, M ?' (mono 44).","tts_text":"الـ aluminum الـ atomic number بتاعه thirteen، خلّينا نوزّع الـ electrons بتوعه.","screen_text":"Aluminum (Z = 13): K ?, L ?, M ?","pause_after_s":0.3},{"id":"s3l3","visual":"Checklist row 'Step 1: Z = 13 → 13 electrons' turns bright on cue YK.cueX('s3l3','الأولى'); the cloud's 13 dots pulse once on cue 'thirteen'.","tts_text":"الخطوة الأولى: الذرة فيها thirteen electrons، زي الـ atomic number بالظبط.","screen_text":"Step 1: Z = 13 → 13 electrons","pause_after_s":0.3},{"id":"s3l4","visual":"Row 'Step 2' bright; two dots fly into ring K (YK.flyer) on cue YK.cueX('s3l4','two'); formula '13 - 2 = 11' builds; cloud shows 11 on cue 'eleven'. Ring K tag '2' only once full.","tts_text":"الـ K الأول بياخد two، و thirteen minus two equals eleven في الانتظار.","screen_text":"Step 2: K takes 2 → 13 − 2 = 11 left","pause_after_s":0.3},{"id":"s3l5","visual":"Row 'Step 3' bright; eight dots fly into ring L on cue YK.cueX('s3l5','eight') (no counter during the flight; tag '8' when full); formula '11 - 8 = 3'; cloud shows 3 on cue 'three'.","tts_text":"وبعده الـ L بياخد eight، و eleven minus eight equals three لسه.","screen_text":"Step 3: L takes 8 → 11 − 8 = 3 left","pause_after_s":0.3},{"id":"s3l6","visual":"Row 'Step 4' bright; the last 3 dots fly into ring M on cue YK.cueX('s3l6','بيروحوا'); tag '3' on ring M; YK.answerSlot(ctx, t, {at:YK.cueX('s3l6','آخر'), text:'2, 8, 3', x:96, y:820}).","tts_text":"والـ three الباقيين بيروحوا الـ M، وده آخر level عند الذرة دي.","screen_text":"Step 4: M takes the 3 → 2, 8, 3","pause_after_s":0.3},{"id":"s3l7","visual":"YK.formula '2 + 8 + 3 = 13' (mono 48) under the answer; the three ring tags pulse on their spoken numbers; a gold arc path links '13' back to Step 1 on cue 'thirteen'; YK.rightMark on cue 'مظبوط'.","tts_text":"ونتأكد: two plus eight plus three equals thirteen، مظبوط كده.","screen_text":"Check: 2 + 8 + 3 = 13 ✓","pause_after_s":0.4},{"id":"s3l8","visual":"Ring M highlighted (highlightShell:2) on cue YK.cueX('s3l8','الخارجي'); its 3 dots glow gold on cue 'three'; YK.tag '3 valence electrons' (gold) beside ring M on cue 'valence'.","tts_text":"والـ M هو الـ level الخارجي، فالـ aluminum عنده three valence electrons برّه.","screen_text":"Outermost level: M → 3 valence electrons","pause_after_s":0.6},{"id":"s3l9","visual":"Picture change: the Al result shrinks to the top of the text panel as a model; stage: empty rings YK.atom(ctx, 1300, 600, {shells:[0,0,0,0], nucleusLabel:'', size:400}) + 19 dots waiting above on cue YK.cueX('s3l9','potassium'); formula 'Potassium (Z = 19)' with '19' gold on cue 'nineteen'.","tts_text":"دورك: الـ potassium فيه nineteen electrons. وزّعهم، وكام valence electron عنده؟","screen_text":"Your turn: Potassium (Z = 19). K, L, M, N? Valence electrons?","pause_after_s":0.3},{"id":"s3l10","visual":"YK.predictCard(ctx, t, {kind:'QUICK CHECK', q:'K ?, L ?, M ?, N ? · valence electrons?', at:YK.cue('s3l10'), until:YK.cue('s3l11'), think:YK.cueEnd('s3l10'), end:YK.cue('s3l11')}) with its think ring through the whole pause; during the silence ONLY the question shows (no dots move, no answer).","tts_text":"وقّف الفيديو، وزّع، وعدّ الـ valence electrons، وافتكر الـ calcium كويس.","screen_text":"Pause: K ?, L ?, M ?, N ? · valence electrons?","pause_after_s":4},{"id":"s3l11","visual":"Dots fly into rings K, L, M on cues 'two', 'تمانية' (#0), 'تمانية' (#1) (YK.flyer; tags '2', '8', '8' only when full); 1 dot left in the cloud.","tts_text":"الحل: الـ K ياخد two، والـ L eight، والـ M eight كمان.","screen_text":"K 2 → L 8 → M 8","pause_after_s":0.3},{"id":"s3l12","visual":"The last dot flies into ring N on cue YK.cueX('s3l12','يروح'); YK.answerSlot(ctx, t, {at:YK.cueX('s3l12','potassium'), text:'Potassium (Z = 19): 2, 8, 8, 1', x:96, y:820}); ring tags '2', '8', '8', '1' pulse on the spoken numbers.","tts_text":"والـ one اللي فاضل يروح الـ N، فالـ potassium: two، eight، eight، one بالترتيب.","screen_text":"Potassium (Z = 19): 2, 8, 8, 1 ✓","pause_after_s":0.3},{"id":"s3l13","visual":"Answer reason: YK.formula '2 + 8 + 8 + 1 = 19' (mono 44) on cue YK.cueX('s3l13','nineteen'); YK.bracket around ring M on cue 'eight' (8 of 18, as in s2l20); ring N highlighted and its dot gold on cue 'valence'; YK.tag '1 valence electron' + YK.rightMark.","tts_text":"المجموع nineteen، والـ M أخد eight، فالـ N فيه one valence electron بس.","screen_text":"2 + 8 + 8 + 1 = 19 · M has 8, then N starts → 1 valence electron","pause_after_s":0.8},{"id":"s4l1","visual":"Header 'Where the levels are used next' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الـ levels دي هتقابلها تاني فين؟","screen_text":"Where the levels are used next","pause_after_s":0.8},{"id":"s4l2","visual":"Stage: the Ca atom again (2, 8, 8, 2), ring N pulsing on cue YK.cueX('s4l2','N'); YK.chip(ctx, 96, 300, 'Energy sublevels', {kind:'concept', align:'left'}) on cue 'energy'. No sublevel drawn (taught there).","tts_text":"في درس الـ energy sublevels، هتعرف ليه الـ calcium بدأ في الـ N بدري.","screen_text":"Energy sublevels","pause_after_s":0.3},{"id":"s4l3","visual":"YK.chip(ctx, 96, 400, 'Ions', {kind:'concept', align:'left'}) on cue YK.cueX('s4l3','ions'); stage: two small atoms side by side: YK.atom(ctx, 1080, 600, {shells:[2,8,1], size:260}) whose outer dot leaves with a trail on cue YK.cueX('s4l3','بتخسر'), and YK.atom(ctx, 1560, 600, {shells:[2,8,7], size:260}) that receives one cyan dot (YK.flyer) on cue 'بتكسب'; outer rings glow on cue 'الخارجي'; no charge signs, no ion names written.","tts_text":"وفي الـ ions، ذرات الـ main-group بتكسب أو بتخسر electrons في الـ level الخارجي.","screen_text":"Ions","pause_after_s":0.3},{"id":"s4l4","visual":"YK.chip(ctx, 96, 500, 'Periodic table: periods and groups', {kind:'concept', align:'left'}) on cue YK.cueX('s4l4','periodic'); stage: YK.periodicTable(ctx, 820, 200, 980, {highlight:{periods:[4]}, hp:0, fBlock:false, labels:false}) fades in dimmed; on cue 'periods' one row glows, on cue 'groups' one column glows (no numbers taught).","tts_text":"وفي الـ periodic table، الـ periods والـ groups مبنية على الـ levels دي.","screen_text":"Periodic table: periods and groups","pause_after_s":0.3},{"id":"s4l5","visual":"Same table: period 4 highlighted (hp:1) on cue YK.cueX('s4l5','period'); cell Ca glows on cue 'calcium' and the ten cells after it (Sc → Zn) get a gold YK.bracket on cue 'بالظبط' (book p.4). YK.tag 'Chapter 1' (gold) top-left of the stage on cue 'الباب'.","tts_text":"في الباب الأول، أول transition series في الـ period الرابع، بعد الـ calcium بالظبط.","screen_text":"Chapter 1 · first transition series: 4th period, after calcium","pause_after_s":0.6},{"id":"s4l6","visual":"Recap (s4l6–s4l8 ≤ 20 s): YK.takeaway(ctx, {title:'Levels K to N', line:'Levels K to N hold at most 2n² electrons.', formula:'K 2 · L 8 · M 18 · N 32', t, pulse:[{word:'K', at:YK.cueX('s4l6','K')}, {word:'N', at:YK.cueX('s4l6','N')}]}) on cue YK.cueX('s4l6','الخلاصة'); the Ca atom small at the stage edge with ring tags K, L, M, N.","tts_text":"الخلاصة: الـ levels من جوه لبرّه، K و L و M و N، وكده.","screen_text":"K, L, M, N, … : n = 1, 2, 3, 4, …","pause_after_s":0.3},{"id":"s4l7","visual":"Takeaway card stays; ring N of the small Ca atom glows gold with its 2 dots on cue YK.cueX('s4l7','valence'); a small mint line under the card 'Outermost level → valence electrons' (36).","tts_text":"والـ electrons اللي في الـ level الخارجي، هي الـ valence electrons بتاعة الذرة.","screen_text":"Outermost level → valence electrons","pause_after_s":0.3},{"id":"s4l8","visual":"Voiced lock-in = the takeaway line 'Levels K to N hold at most 2n² electrons.'; its words pulse on cues 'K', 'N', 'squared' and stay gold; card held through the line + 1.5 s tail; last frame = the takeaway card with the full Ca atom (no fade to black).","tts_text":"الـ levels من الـ K لحد الـ N، بتشيل two n squared electrons بالكتير.","screen_text":"Levels K to N hold at most 2n² electrons.","pause_after_s":1.5}],"logline":"هتعرف أسماء الـ levels حوالين الـ nucleus، وكل level بيشيل كام electron، وتوزّع الـ electrons لحد الـ calcium وتلاقي الـ valence electrons.","segments":[{"id":"s1","title":"A stadium, its rows and electrons","concept_id":"atom.energy-levels"},{"id":"s2","title":"Level names and the two n squared rule","concept_id":"atom.energy-levels"},{"id":"s3","title":"Arranging the electrons of aluminum","concept_id":"atom.energy-levels"},{"id":"s4","title":"Where the levels are used 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ملعب كورة المدرجات حوالين الملعب صف\nورا صف\nالصف اللي قريب من الملعب صغير واللي بعيد\nأكبر وبياخد ناس أكتر\nالذرة كمان ليها مركز في النص اسمه الـ\nnucleus زي الملعب كده\nوحوالين الـ nucleus بتتحرك جسيمات صغيرة\nسالبة اسمها electrons زي الجمهور\nالـ calcium مثلًا فيه twenty electrons\nبيتحركوا حوالين الـ nucleus بتاعه\nالـ electrons دي بتتحرك في مناطق حوالين\nالـ nucleus اسمها main energy levels\nمستويات\nيعني الـ electrons زي الجمهور والـ levels\nزي صفوف المدرجات حوالين الملعب\nالسؤال بقى الـ level يقدر يشيل كام\nelectron بالكتير\nمن جوه لبرّه أسماء الـ levels K و L و M و\nN وكده\nورقم الـ level بنسميه n one two three four\nوكده\nوالـ level اللي أبعد عن الـ nucleus الـ\nenergy بتاعته أعلى\nوزي المدرجات الـ level اللي أبعد بيشيل\nelectrons أكتر\nوالقاعدة أقصى عدد electrons في الـ level\nهو two n squared بالظبط\nيعني n squared هي n times n three times\nthree equals nine بالظبط\nالـ K رقمه one two times one squared\nequals two يعني two electrons بالكتير\nوالـ L رقمه two two times four equals\neight يعني eight electrons بالكتير\nتوقّع الـ M level بيشيل eight ولا sixteen\nولا eighteen بالكتير\nناس كتير بتقول eight زي الـ L أو sixteen\nبالضعف ده غلط\nنحسبها بالقاعدة الـ M رقمه three two times\nnine equals eighteen بالظبط\nيعني السعة جاية من رقم الـ level مش من الـ\nlevel اللي قبله\nوالـ N رقمه four two times sixteen equals\nthirty-two كمان\nخلّي بالك القاعدة دي لأول four levels من\nالـ K لحد الـ N تحديدًا\nالـ atomic number أو Z هو عدد الـ\nelectrons في الذرة الـ neutral المتعادلة\nلحد الـ argon الأول الـ K بعدين الـ L\nبعدين الـ M كمان\nالـ calcium فيه twenty two و eight و eight\nو two في الـ N برّه\nناس بتفتكر إن الـ M اتملى عند eight ده غلط\nالـ M يقدر يشيل eighteen وفي الـ calcium\nفيه eight ولسه فيه مكان\nوليه electron nineteen و twenty بيروحوا\nالـ N ده في درس جاي\nاللي في آخر energy level من برّه اسمهم\nvalence electrons زي الـ two دول\nده في ذرات الـ main-group زي اللي معانا في\nالدرس ده\nالـ aluminum الـ atomic number بتاعه\nthirteen خلّينا نوزّع الـ electrons بتوعه\nالخطوة الأولى الذرة فيها thirteen\nelectrons زي الـ atomic number بالظبط\nالـ K الأول بياخد two و thirteen minus two\nequals eleven في الانتظار\nوبعده الـ L بياخد eight و eleven minus\neight equals three لسه\nوالـ three الباقيين بيروحوا الـ M وده آخر\nlevel عند الذرة دي\nونتأكد two plus eight plus three equals\nthirteen مظبوط كده\nوالـ M هو الـ level الخارجي فالـ aluminum\nعنده three valence electrons برّه\nدورك الـ potassium فيه nineteen electrons\nوزّعهم وكام valence electron عنده\nوقّف الفيديو وزّع وعد الـ valence\nelectrons وافتكر الـ calcium كويس\nالحل الـ K ياخد two والـ L eight والـ M\neight كمان\nوالـ one اللي فاضل يروح الـ N فالـ\npotassium two eight eight one بالترتيب\nالمجموع nineteen والـ M أخد eight فالـ N\nفيه one valence electron بس\nطب الـ levels دي هتقابلها تاني فين\nفي درس الـ energy sublevels هتعرف ليه الـ\ncalcium بدأ في الـ N بدري\nوفي الـ ions ذرات الـ main-group بتكسب أو\nبتخسر electrons في الـ level الخارجي\nوفي الـ periodic table الـ periods والـ\ngroups مبنية على الـ levels دي\nفي الباب الأول أول transition series في\nالـ period الرابع بعد الـ calcium بالظبط\nالخلاصة الـ levels من جوه لبرّه K و L و M\nو N وكده\nوالـ electrons اللي في الـ level الخارجي\nهي الـ valence electrons بتاعة الذرة\nالـ levels من الـ K لحد الـ N بتشيل two n\nsquared electrons بالكتير","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":68,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":101.08,"kind":"pause_question","spec":{"answer":"18: بالقاعدة 2n²، يعني 2 × 3² = 2 × 9 = 18.","prompt":"الـ M level (n = 3) بيشيل بالكتير كام electron؟","options":[{"id":"a","text":"8","correct":false},{"id":"b","text":"16","correct":false},{"id":"c","text":"18","correct":true}],"answer_t_s":104.74,"concept_id":"atom.energy-levels"},"content_lang":"ar-EG"},{"id":"think-2","t_s":234.68,"kind":"pause_question","spec":{"answer":"2, 8, 8, 1: الـ M فيه 8 وبعدين الـ N بيبدأ، فعنده 1 valence electron.","prompt":"الـ potassium (Z = 19): الـ electrons على K, L, M, N، وكام valence electron؟","options":[{"id":"a","text":"2, 8, 8, 1 · 1 valence electron","correct":true},{"id":"b","text":"2, 8, 9 · 9 valence electrons","correct":false},{"id":"c","text":"2, 8, 8, 1 · 8 valence electrons","correct":false}],"answer_t_s":239.27,"concept_id":"atom.energy-levels"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-atom.energy-levels"]},{"id":"chem-s3-en.video-walkthrough-chem.elements-symbols","kind":"walkthrough","version":7,"ord":10,"content_lang":"ar-EG","primary_concept_id":"chem.elements-symbols","concepts":[{"concept_id":"chem.elements-symbols","role":"primary"}],"title":"Elements and their symbols: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.elements-symbols v1 (s1 hook 'Co is a metal used to make magnets, but CO is a gas', MCQ options 'Cobalt, written in capitals' / 'Carbon (C) joined to oxygen (O)' / 'A new element called CO'; s2 KeyTerm 'Element' definition (used verbatim on the term card), rules 'One capital letter: C (carbon), V (vanadium)', 'A capital + a small letter: Co (cobalt)', 'from Latin: Fe (ferrum, iron), Cu (cuprum, copper)', 'CO: two capitals: two symbols, carbon + oxygen'; s3 the ten elements of Ch.1 p.5; s4 sort Ni/TiO2/Co/CO/N2/CuO and KMnO4 count (NOT reused, so the video does not give away the lesson's checks); s5 recap 'Each capital letter starts a new symbol' and the O2 vs CO reveal). Concept chem.elements-symbols v2 (no recorded misconceptions: s2 refutes the lesson hook's two wrong options 'CO = cobalt in capitals' and 'CO = a new element' (s2l10 ✕) with the capital-letter rule (s2l11) and CO = C + O, 2 kinds of atom -> compound (s2l12-s2l14); O2 shows two atoms of one kind is still an element (s2l15-s2l16)). Book: p.5 first transition series Sc -> Zn ten elements and 'Titanium dioxide (TiO2)'; p.8 table lists MnO2 (worked example) ; periodic table figure lists Cl Chlorine (self-check Cl2). Dependents named in s4 (map titles, spoken): chem.elements-compounds-mixtures 'Elements, compounds and mixtures', chem.valency-formulas 'Valency and writing chemical formulas', chem.metal-properties 'Properties of metals and non-metals', pt.groups-periods 'Periodic table: periods and groups'; no details of them taught (mixtures not drawn, no valency numbers, no properties listed). Terms (defined at first use): s1 atom, Element, pure substance (3); s2 symbol, capital / small (letter shapes), compound. Worked example MnO2 (3 steps: capitals -> symbols -> kinds of atom); self-check NEW case Cl2 (chlorine) -> element (one capital + small = one symbol; 2 atoms of one kind), pause 4 s. Voicing: subscripts read as English number words after the formula («MnO two», «Cl two», «O two», «TiO two») because this lesson is about reading symbols; letters inside symbols said as Latin letters with «capital/small». not-in-source: 'compound: more than one kind of atom' as a short gloss (lesson: 'two kinds of atom, so it is a compound'); copper wire inside a household cable (anchor); 'the small 2 = two atoms' (subscript meaning, textbook-true, lesson implies it for O2); 'Cl2 is the gas of chlorine' (textbook-true). Estimated duration ≈ 4.5 min (543 words at ~2.4 words/s + 27 s of pauses).","title":"Elements and their symbols: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor, stage x 790–1824: a household cable drawn with ctx paths (C.night insulation tube, rounded) at (1300, 560); on cue YK.cueX('s1l2','البلاستيك') the insulation peels back (clip tween) to show a shiny C.steel metal core with a sweep highlight (YK.glowCircle moving along it) on cue 'لامع'; YK.tag 'copper' (44) on the core on cue 'copper'. No colour claim beyond 'shiny'.","tts_text":"بص على سِلك الكهربا اللي في البيت: جوه البلاستيك فيه سِلك copper لامع.","screen_text":"A copper wire","pause_after_s":0.4},{"id":"s1l3","visual":"YK.zoomThrough(ctx, t, {from: drawWire, to: drawGrid, focus: wire core, badge:'×10^8'}) starting on cue YK.cueX('s1l3','كبّرنا'): the core opens into a neat grid of identical YK.atomDisc(ctx, x, y, 40, {el:'Cu'}) discs (6 × 4); YK.scaleBadge in the stage corner. Text panel YK.termCard(ctx, 96, 300, {term:'atom', def:'a tiny particle; matter is made of atoms', align:'left'}) on cue 'atoms'; on cue 'الطوب' a faint brick-wall outline (ctx rects) flashes behind the grid for 1 s.","tts_text":"لو كبّرنا السِلك جدًا، هنلاقيه مبني من حبيبات صغيرة اسمها atoms، زي الطوب.","screen_text":"atom: a tiny particle; matter is made of atoms","pause_after_s":0.4},{"id":"s1l4","visual":"The Cu grid stays; every disc pulses together on cue YK.cueX('s1l4','شبه'); a YK.bracket around the whole grid on cue 'واحد' with YK.tag 'one kind: copper' (gold). Text panel YK.fpara 'Copper wire: one kind of atom (copper)' (44).","tts_text":"وفي سِلك الـ copper، الـ atoms دي شبه بعض، كلها من نوع واحد.","screen_text":"Copper wire: one kind of atom (copper)","pause_after_s":0.4},{"id":"s1l5","visual":"Stage left: two glass jars drawn with YK.beaker(ctx, …): left jar filled with identical Cu discs on cue YK.cueX('s1l5','pure') (YK.rightMark), right jar with Cu discs mixed with grey 'sand' grains (ctx dots) on cue 'متخلطة' (coral outline, no label). YK.tag 'pure substance' over the left jar.","tts_text":"الـ pure substance يعني مادة مفيهاش أي مادة تانية متخلطة معاها.","screen_text":"pure substance: no other substance mixed in","pause_after_s":0.4},{"id":"s1l6","visual":"Picture change: Cu grid shrinks to the right half of the stage. Text panel YK.termCard(ctx, 96, 240, {term:'Element', def:'A pure substance made of only one kind of atom. It cannot be broken down into simpler substances by chemical methods.', keys:['one kind of atom'], align:'left'}) on cue YK.cueX('s1l6','element'); the key 'one kind of atom' turns gold on cue 'واحد'.","tts_text":"والـ element هو pure substance، فيها نوع واحد بس من الـ atoms جواها.","screen_text":"Element: a pure substance made of only one kind of atom. It cannot be broken down into simpler substances by chemical methods.","pause_after_s":0.4},{"id":"s1l7","visual":"Stage: one Cu disc in a YK.tube with a flame glyph (YK.icon('flask') + C.heatRed glow) on cue YK.cueX('s1l7','نكسّره'); the disc shakes but stays one Cu disc (no split) on cue 'أبسط'; text panel: the second sentence of the term card glows gold on the same cue.","tts_text":"والـ element مينفعش نكسّره لمواد أبسط منه، بالطرق الكيميائية.","screen_text":"cannot be broken down into simpler substances by chemical methods","pause_after_s":0.4},{"id":"s1l8","visual":"Picture change: three small grids side by side on the stage, each of identical YK.atomDisc discs: 'Cu' grid (copper), 'Fe' grid (iron) on cue YK.cueX('s1l8','iron'), a loose cloud of paired 'O' discs (oxygen) on cue 'oxygen'; tags 'copper', 'iron', 'oxygen' under them; YK.tag '…' after them on cue 'وغيرهم'.","tts_text":"والـ iron element، والـ oxygen اللي في الهوا element، والـ copper، وغيرهم كتير.","screen_text":"Elements: copper, iron, oxygen, …","pause_after_s":0.4},{"id":"s1l9","visual":"Text panel: the word 'manganese' typed letter by letter (YK.fpara 48) three times down the panel (one per beat, cues 'كتابة', 'بالكامل', 'طويلة'); a big gold '?' path on the stage on cue 'أقصر'.","tts_text":"بس كتابة اسم الـ element بالكامل كل مرة طويلة، فيه طريقة أقصَر؟","screen_text":"Writing the full name every time? A shorter way?","pause_after_s":1},{"id":"s2l2","visual":"Text panel YK.termCard(ctx, 96, 280, {term:'symbol', def:'a short way to write an element, in Latin letters', align:'left'}) on cue YK.cueX('s2l2','symbol'); stage: the word 'carbon' (YK.formula 72) shrinks into a tile with 'C' (YK.panel tile, YK.formula 120) on cue 'اختصار' (#0).","tts_text":"أي element ليه symbol، يعني اختصار بحروف لاتيني، زي اختصار اسمك.","screen_text":"symbol: a short way to write an element, in Latin letters","pause_after_s":0.4},{"id":"s2l3","visual":"Stage: a big 'C' (Cairo 1000, 220) on cue YK.cueX('s2l3','capital') with YK.tag 'capital'; a small 'c' (Cairo 800, 110) beside it on cue 'small' with YK.tag 'small'; the two letters are drawn with the same baseline so the size difference is clear.","tts_text":"الحروف اللاتيني ليها شكلين: capital كبير زي ده، و small صغير زي ده.","screen_text":"capital: C · small: c","pause_after_s":0.4},{"id":"s2l4","visual":"Picture change: symbol tiles row (YK.panel tiles 220 × 220, YK.formula 120 inside, name tag under): tile 'C' + tag 'carbon' on cue YK.cueX('s2l4','carbon'); the C glows gold on cue 'لوحده'. Text panel YK.fpara 'One capital: C (carbon)' (44).","tts_text":"ساعات الـ symbol حرف capital واحد، زي الـ carbon: رمزه C لوحده.","screen_text":"One capital: C (carbon)","pause_after_s":0.3},{"id":"s2l5","visual":"Second tile 'V' + tag 'vanadium' slides in beside 'C' on cue YK.cueX('s2l5','vanadium'); the V glows on cue 'لوحده'.","tts_text":"وكمان الـ vanadium، رمزه V capital لوحده من غير حرف تاني.","screen_text":"One capital: V (vanadium)","pause_after_s":0.3},{"id":"s2l6","visual":"Third tile 'Co' + tag 'cobalt' on cue YK.cueX('s2l6','cobalt'); inside the tile the 'C' pulses gold on cue 'capital' and the 'o' pulses violet on cue 'small'; a thin bracket joins both letters as one symbol. Text panel YK.fpara 'A capital + a small letter: Co (cobalt)' (44).","tts_text":"وساعات حرفين: الـ cobalt رمزه C capital، وبعدها o small جنبها.","screen_text":"A capital + a small: Co (cobalt)","pause_after_s":0.3},{"id":"s2l7","visual":"Picture change: tile 'Fe' + tag 'iron' on cue YK.cueX('s2l7','iron'); above it the old word 'ferrum' (YK.formula 64, textDim) appears on cue 'ferrum' with its first two letters 'Fe' turning gold and dropping into the tile (YK.tween).","tts_text":"وفيه symbols جاية من اللاتيني: الـ iron رمزه Fe، من ferrum زمان.","screen_text":"From Latin: Fe (ferrum, iron)","pause_after_s":0.3},{"id":"s2l8","visual":"Same beat: tile 'Cu' + tag 'copper' on cue YK.cueX('s2l8','copper'); 'cuprum' above it, 'Cu' gold and dropping into the tile on cue 'cuprum'. The copper wire anchor (small, corner) glows once.","tts_text":"وكمان الـ copper رمزه Cu، من الاسم القديم cuprum بالظبط.","screen_text":"From Latin: Cu (cuprum, copper)","pause_after_s":0.4},{"id":"s2l9","visual":"YK.predictCard(ctx, t, {kind:'PREDICT', q:'Is CO still cobalt?', at:YK.cue('s2l9'), until:YK.cue('s2l10'), think:YK.cueEnd('s2l9'), end:YK.cue('s2l10')}); stage: tile 'Co' and a new tile 'CO' side by side, the 'O' of 'CO' pulsing on cue 'capital'; during the silence only the question and the think ring move.","tts_text":"توقّع: لو كتبنا الـ o capital، يعني CO، يبقى cobalt برضه؟","screen_text":"Predict: is CO still cobalt?","pause_after_s":3},{"id":"s2l10","visual":"Myth beat (lesson hook wrong options a and c): YK.mythLine(ctx, t, {at:YK.cue('s2l10'), wrongAt:YK.cueX('s2l10','غلط'), until:YK.cueEnd('s2l10')+0.4, text:'CO = cobalt in capitals? · CO = a new element?', x:96, y:300, size:48}) coral; YK.wrongMark on cue 'غلط', held for the myth's whole visible time; nothing struck through.","tts_text":"ناس بتقول ده cobalt بحروف capital، أو element جديد. الاتنين غلط.","screen_text":"CO = cobalt in capitals? · CO = a new element?","pause_after_s":0.3},{"id":"s2l11","visual":"Right rule, held longer than the myth: text panel YK.fpara 'Each capital letter starts a new symbol' (48, 'capital' gold) on cue YK.cueX('s2l11','القاعدة'); stage: tile 'CO' splits into two tiles 'C' | 'O' with a gold cut line on cue 'جديد'; tile 'Co' stays whole with its joining bracket on cue 'بيكمّل'. YK.rightMark.","tts_text":"القاعدة: أي capital letter بيبدأ symbol جديد، والـ small بيكمّل اللي قبله.","screen_text":"Each capital letter starts a new symbol","pause_after_s":0.4},{"id":"s2l12","visual":"Tiles 'C' + tag 'carbon' on cue YK.cueX('s2l12','carbon'), 'O' + tag 'oxygen' on cue 'oxygen'; under them YK.molecule(ctx, 1300, 760, {name:'CO', size:160}) builds on cue 'two' (two different discs joined).","tts_text":"يعني CO فيها two symbols: الـ C هو carbon، والـ O هو oxygen كمان.","screen_text":"CO: 2 symbols → C (carbon) + O (oxygen)","pause_after_s":0.3},{"id":"s2l13","visual":"Split stage (lesson hook): left a small metal block with the 'Co' tile (YK.cube-style shaded rect, C.steel) and tag 'metal' on cue YK.cueX('s2l13','metal'); right a puff of CO molecules (YK.molecule CO ×4 drifting, seeded YK.rng(3)) with tag 'gas' on cue 'gas'. No colour claims.","tts_text":"الـ cobalt ده metal، أما الـ CO فده gas تاني خالص.","screen_text":"Co: a metal · CO: a gas","pause_after_s":0.4},{"id":"s2l14","visual":"CO molecule enlarged: C disc and O disc each get a different colour ring on cue YK.cueX('s2l14','نوعين'); text panel YK.termCard(ctx, 96, 300, {term:'compound', def:'a pure substance made of two or more kinds of atom chemically joined', keys:['two or more kinds of atom'], align:'left'}) on cue 'compound'; YK.tag '2 kinds of atom' (gold). No strike on 'not element'.","tts_text":"الـ CO فيها نوعين atoms، يبقى مش element؛ دي pure substance اسمها compound، مركّب.","screen_text":"2 kinds of atom → compound, not element","pause_after_s":0.4},{"id":"s2l14b","visual":"YK.termCard(ctx, 96, 300, {term:'formula', def:'the symbols of a substance written together', align:'left'}) on cue YK.cueX('s2l14b','formula'); the CO tile pulses on cue 'ورا'","tts_text":"والـ symbols اللي بنكتبها ورا بعض لأي substance، اسمها formula، يعني صيغة.","screen_text":"formula: the symbols of a substance written together","pause_after_s":0.4},{"id":"s2l15","visual":"Picture change: YK.formula 'O_2' (mono 140) on cue YK.cueX('s2l15','O'); the subscript '2' pulses gold on cue 'الصغير' and a gold arrow path points down to two identical YK.atomDisc el 'O' discs joined, appearing on cue 'atoms'.","tts_text":"طب الـ O two؟ الرقم الصغير two معناه فيه two atoms oxygen متلزقين.","screen_text":"O₂: the 2 = two atoms of oxygen","pause_after_s":0.3},{"id":"s2l16","visual":"The two O discs pulse together (same colour ring) on cue YK.cueX('s2l16','واحد'); YK.tag 'one kind: oxygen' + YK.rightMark on cue 'element'; text panel YK.fpara 'O₂: one kind of atom → element' (44); beside it the CO picture returns small for contrast (2 kinds) on cue 'compound'.","tts_text":"الـ O two element، مش compound، عشان الـ two oxygen atoms من نوع واحد.","screen_text":"O₂: one kind of atom → element","pause_after_s":0.6},{"id":"s3l2","visual":"Stage: YK.formula 'MnO_2' (mono 160) centred at (1300, 420) on cue YK.cueX('s3l2','MnO'); a small source note 'p.8' (32, textDim). Text panel: a 3-step checklist (YK.fpara rows 'Step 1: capitals', 'Step 2: symbols', 'Step 3: kinds of atom', dim).","tts_text":"خد الـ MnO two من جدول الكتاب: يا ترى element ولا compound ده؟","screen_text":"MnO₂: element or compound?","pause_after_s":0.3},{"id":"s3l3","visual":"Row 'Step 1' bright; inside 'MnO_2' the 'M' and the 'O' get gold YK.bracket boxes on cue YK.cueX('s3l3','capital'), the 'n' and the '2' dim to 35% on cue 'حرفين'.","tts_text":"الخطوة الأولى: ندوّر على الـ capital letters، هنا حرفين بس.","screen_text":"Step 1: capitals: M, O","pause_after_s":0.3},{"id":"s3l4","visual":"Row 'Step 2' bright; the 'n' rejoins the 'M' under one bracket on cue YK.cueX('s3l4','small'); the formula splits into tiles 'Mn' + tag 'manganese' on cue 'manganese' and 'O' + tag 'oxygen' (shown as the tile appears).","tts_text":"الخطوة التانية: الـ M ومعاه n small، يبقى Mn، والـ manganese رمزه كده.","screen_text":"Step 2: Mn (manganese)","pause_after_s":0.3},{"id":"s3l5","visual":"Tile 'O' + tag 'oxygen' pulses on cue YK.cueX('s3l5','oxygen'); the subscript '2' pulses gold on cue 'الصغير'; on the stage a particle picture builds: one YK.atomDisc el 'Mn' joined to two YK.atomDisc el 'O' on cue 'atoms'.","tts_text":"والـ O هو oxygen، والرقم الصغير two يعني two atoms منه.","screen_text":"O (oxygen) · 2 = 2 O atoms","pause_after_s":0.3},{"id":"s3l6","visual":"Row 'Step 3' bright; the Mn disc and the O discs get two different colour rings on cue YK.cueX('s3l6','نوعين'); YK.answerSlot(ctx, t, {at:YK.cueX('s3l6','compound'), text:'MnO₂: compound (2 kinds of atom)', x:96, y:820}).","tts_text":"الخطوة التالتة: نوعين atoms، manganese و oxygen، يعني ده compound أكيد.","screen_text":"Step 3: 2 kinds of atom → compound","pause_after_s":0.4},{"id":"s3l7","visual":"The subscript '2' circled with a gold YK.bracket on cue YK.cueX('s3l7','رقم'); a small tag '2 = how many' (textDim) under it; no ✕ on this negated sentence.","tts_text":"وخلّي بالك: الـ two ده رقم، مش symbol، فمش بنعدّه نوع جديد.","screen_text":"The 2 is a number, not a symbol","pause_after_s":0.6},{"id":"s3l8","visual":"Picture change: MnO₂ result shrinks to the top of the text panel as a model; stage YK.formula 'Cl_2' (mono 160) on cue YK.cueX('s3l8','Cl'); tag 'chlorine' on cue 'chlorine'. No atoms drawn yet.","tts_text":"دورك: الـ chlorine رمزه Cl، والغاز بتاعه مكتوب Cl two كده.","screen_text":"Your turn: Cl₂ (chlorine)","pause_after_s":0.3},{"id":"s3l9","visual":"YK.predictCard(ctx, t, {kind:'QUICK CHECK', q:'Element or compound?', at:YK.cue('s3l9'), until:YK.cue('s3l10'), think:YK.cueEnd('s3l9'), end:YK.cue('s3l10')}) + think ring through the whole pause; the 3-step checklist re-lights dimly; during the silence ONLY the question shows. The Cl₂ formula stays on the stage.","tts_text":"هو element ولا compound؟ وقّف الفيديو وجرّب بنفس الخطوات.","screen_text":"Element or compound?","pause_after_s":4},{"id":"s3l10","visual":"Answer step 1–2: the 'C' of 'Cl_2' gets a gold bracket on cue YK.cueX('s3l10','capital'), the 'l' joins it under the same bracket on cue 'بتكمّله'; tile 'Cl' + tag 'chlorine' on cue 'chlorine'.","tts_text":"الحل: فيه capital واحد، والـ l small بتكمّله: Cl، ده symbol الـ chlorine لوحده.","screen_text":"One capital → one symbol: Cl (chlorine)","pause_after_s":0.3},{"id":"s3l11","visual":"Two identical YK.atomDisc el 'Cl' discs joined appear on cue YK.cueX('s3l11','atoms'), both pulse together on cue 'النوع'; YK.answerSlot(ctx, t, {at:YK.cueX('s3l11','element'), text:'Cl₂: element (one kind of atom)', x:96, y:820}) + YK.rightMark.","tts_text":"يبقى Cl two فيها two atoms من نفس النوع، يعني element طبعًا.","screen_text":"Cl₂: two atoms, one kind → element ✓","pause_after_s":0.3},{"id":"s3l12","visual":"Side by side: the MnO₂ picture (2 kinds, two colour rings) and the Cl₂ picture (1 kind, one colour ring) on cue YK.cueX('s3l12','أنواع'); text panel YK.fpara 'Reason: count the kinds of atom, not the letters' (44). No strike.","tts_text":"والسبب إننا بنعِدّ أنواع الـ atoms، مش عدد الحروف ولا الأرقام.","screen_text":"Reason: count the kinds of atom, not the letters","pause_after_s":0.8},{"id":"s4l1","visual":"Header 'Where the symbols are used next' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الـ symbols دي هتقابلها فين تاني؟","screen_text":"Where the symbols are used next","pause_after_s":0.8},{"id":"s4l2","visual":"YK.chip(ctx, 96, 280, 'Elements, compounds and mixtures', {kind:'concept', align:'left'}) on cue YK.cueX('s4l2','elements'); stage: the Cl₂ (element) and MnO₂ (compound) pictures from s3 side by side, each glowing on cues 'elements' and 'compounds'. Mixtures not drawn (taught there).","tts_text":"في درس الـ elements والـ compounds والـ mixtures، هتفرّق بينهم بالـ symbols دي.","screen_text":"Elements, compounds and mixtures","pause_after_s":0.3},{"id":"s4l3","visual":"YK.chip(ctx, 96, 380, 'Valency and writing chemical formulas', {kind:'concept', align:'left'}) on cue YK.cueX('s4l3','valency'); stage: tiles 'Cu' and 'O' slide together into 'CuO' (YK.formula) on cue 'هتركّب'. No valency numbers shown.","tts_text":"وفي الـ valency وكتابة الـ chemical formulas، هتركّب symbols مع بعض.","screen_text":"Valency and writing chemical formulas","pause_after_s":0.3},{"id":"s4l4","visual":"YK.chip(ctx, 96, 480, 'Properties of metals and non-metals', {kind:'concept', align:'left'}) on cue YK.cueX('s4l4','metals'); stage: tiles 'Fe', 'Cu' (left group) and 'O', 'Cl' (right group) on cues 'metals' and 'non'. No properties listed.","tts_text":"وفي خواص الـ metals والـ non-metals، هتقابل نفس الـ elements دي.","screen_text":"Properties of metals and non-metals","pause_after_s":0.3},{"id":"s4l5","visual":"YK.chip(ctx, 96, 580, 'Periodic table: periods and groups', {kind:'concept', align:'left'}) on cue YK.cueX('s4l5','periodic'); stage: YK.periodicTable(ctx, 820, 200, 980, {reveal:YK.prog(t, YK.cueX('s4l5','periodic'), YK.cueEnd('s4l5')), fBlock:false, labels:false}) cells pop in by Z (symbols only).","tts_text":"وفي الـ periodic table، الـ periods والـ groups مليانة symbols زي دي.","screen_text":"Periodic table: periods and groups","pause_after_s":0.3},{"id":"s4l6","visual":"Same table: the ten cells Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn highlighted (highlight:{symbols:[…]}, hp:YK.prog(t, YK.cueX('s4l6','ten'), +0.8)); Sc glows on cue 'scandium', Zn on cue 'zinc' (book p.5). YK.tag 'Chapter 1' (gold) on cue 'الباب'.","tts_text":"وفي الباب الأول، هتقابل ten elements، من الـ scandium لحد الـ zinc بالترتيب.","screen_text":"Chapter 1: 10 elements, scandium → zinc (book p.5)","pause_after_s":0.3},{"id":"s4l7","visual":"Stage: YK.formula 'TiO_2' (mono 120) on cue YK.cueX('s4l7','TiO'), its 'T' and 'O' get gold brackets (capitals) on cue 'القاعدة'; tag 'Titanium dioxide (book p.5)' (36) on cue 'titanium'.","tts_text":"وهتقرا formulas زي الـ titanium dioxide، اللي هو TiO two، بنفس القاعدة.","screen_text":"Titanium dioxide (TiO₂)","pause_after_s":0.6},{"id":"s4l8","visual":"Recap (s4l8–s4l10 ≤ 20 s): YK.takeaway(ctx, {title:'Elements and their symbols', line:'Each capital letter starts a new symbol.', formula:'C · Co · CO', t, pulse:[{word:'capital', at:YK.cueX('s4l10','capital')}, {word:'symbol', at:YK.cueX('s4l10','symbol')}]}) from cue YK.cueX('s4l8','الخلاصة'); a small mint line under the card 'Element: one kind of atom' on cue 'element'.","tts_text":"الخلاصة: الـ element مادة نقية فيها نوع واحد من الـ atoms جواها.","screen_text":"Element: one kind of atom","pause_after_s":0.3},{"id":"s4l9","visual":"Takeaway stays; second mint line 'Symbol: a capital, or a capital + a small' under it; the formula 'C · Co · CO' on the card pulses 'C' on cue YK.cueX('s4l9','لوحده') and 'Co' on cue 'small'.","tts_text":"والـ symbol يا حرف capital لوحده، يا capital ومعاه small جنبه.","screen_text":"Symbol: a capital, or a capital + a small","pause_after_s":0.3},{"id":"s4l10","visual":"Voiced lock-in = the takeaway line 'Each capital letter starts a new symbol.'; its words pulse on cues 'capital' and 'symbol' and stay gold; the 'CO' on the card splits into 'C | O' on cue 'جديد'; card held through the line + 1.5 s tail; last frame = the takeaway card (no fade to black).","tts_text":"افتكر: أي capital letter بيبدأ symbol جديد.","screen_text":"Each capital letter starts a new symbol.","pause_after_s":1.5}],"logline":"هتعرف يعني إيه element، وتقرا الـ symbols صح، وتفرّق بين element زي Co و compound زي CO.","segments":[{"id":"s1","title":"A copper wire: atoms and elements","concept_id":"chem.elements-symbols"},{"id":"s2","title":"Writing element symbols","concept_id":"chem.elements-symbols"},{"id":"s3","title":"Reading the formula MnO2","concept_id":"chem.elements-symbols"},{"id":"s4","title":"Where the symbols are used 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على سِلك الكهربا اللي في البيت جوه\nالبلاستيك فيه سِلك copper لامع\nلو كبّرنا السِلك جدًا هنلاقيه مبني من\nحبيبات صغيرة اسمها atoms زي الطوب\nوفي سِلك الـ copper الـ atoms دي شبه بعض\nكلها من نوع واحد\nالـ pure substance يعني مادة مفيهاش أي\nمادة تانية متخلطة معاها\nوالـ element هو pure substance فيها نوع\nواحد بس من الـ atoms جواها\nوالـ element مينفعش نكسّره لمواد أبسط منه\nبالطرق الكيميائية\nوالـ iron element والـ oxygen اللي في\nالهوا element والـ copper وغيرهم كتير\nبس كتابة اسم الـ element بالكامل كل مرة\nطويلة فيه طريقة أقصَر\nأي element ليه symbol يعني اختصار بحروف\nلاتيني زي اختصار اسمك\nالحروف اللاتيني ليها شكلين capital كبير زي\nده و small صغير زي ده\nساعات الـ symbol حرف capital واحد زي الـ\ncarbon رمزه C لوحده\nوكمان الـ vanadium رمزه V capital لوحده من\nغير حرف تاني\nوساعات حرفين الـ cobalt رمزه C capital\nوبعدها o small جنبها\nوفيه symbols جاية من اللاتيني الـ iron\nرمزه Fe من ferrum زمان\nوكمان الـ copper رمزه Cu من الاسم القديم\ncuprum بالظبط\nتوقّع لو كتبنا الـ o capital يعني CO يبقى\ncobalt برضه\nناس بتقول ده cobalt بحروف capital أو\nelement جديد الاتنين غلط\nالقاعدة أي capital letter بيبدأ symbol\nجديد والـ small بيكمّل اللي قبله\nيعني CO فيها two symbols الـ C هو carbon\nوالـ O هو oxygen كمان\nالـ cobalt ده metal أما الـ CO فده gas\nتاني خالص\nالـ CO فيها نوعين atoms يبقى مش element دي\npure substance اسمها compound مركّب\nوالـ symbols اللي بنكتبها ورا بعض لأي\nsubstance اسمها formula يعني صيغة\nطب الـ O two الرقم الصغير two معناه فيه\ntwo atoms oxygen متلزقين\nالـ O two element مش compound عشان الـ two\noxygen atoms من نوع واحد\nخد الـ MnO two من جدول الكتاب يا ترى\nelement ولا compound ده\nالخطوة الأولى ندوّر على الـ capital\nletters هنا حرفين بس\nالخطوة التانية الـ M ومعاه n small يبقى Mn\nوالـ manganese رمزه كده\nوالـ O هو oxygen والرقم الصغير two يعني\ntwo atoms منه\nالخطوة التالتة نوعين atoms manganese و\noxygen يعني ده compound أكيد\nوخلّي بالك الـ two ده رقم مش symbol فمش\nبنعدّه نوع جديد\nدورك الـ chlorine رمزه Cl والغاز بتاعه\nمكتوب Cl two كده\nهو element ولا compound وقّف الفيديو وجرّب\nبنفس الخطوات\nالحل فيه capital واحد والـ l small بتكمّله\nCl ده symbol الـ chlorine لوحده\nيبقى Cl two فيها two atoms من نفس النوع\nيعني element طبعًا\nوالسبب إننا بنعِد أنواع الـ atoms مش عدد\nالحروف ولا الأرقام\nطب الـ symbols دي هتقابلها فين تاني\nفي درس الـ elements والـ compounds والـ\nmixtures هتفرّق بينهم بالـ symbols دي\nوفي الـ valency وكتابة الـ chemical\nformulas هتركّب symbols مع بعض\nوفي خواص الـ metals والـ non-metals هتقابل\nنفس الـ elements دي\nوفي الـ periodic table الـ periods والـ\ngroups مليانة symbols زي دي\nوفي الباب الأول هتقابل ten elements من الـ\nscandium لحد الـ zinc بالترتيب\nوهتقرا formulas زي الـ titanium dioxide\nاللي هو TiO two بنفس القاعدة\nالخلاصة الـ element مادة نقية فيها نوع\nواحد من الـ atoms جواها\nوالـ symbol يا حرف capital لوحده يا\ncapital ومعاه small جنبه\nافتكر أي capital letter بيبدأ symbol جديد","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":69,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":88.86,"kind":"pause_question","spec":{"answer":"لأ: أي capital letter بيبدأ symbol جديد، فـ CO هي C (carbon) + O (oxygen).","prompt":"لو كتبنا الـ o capital، يعني CO: يبقى cobalt برضه؟","options":[{"id":"a","text":"لأ: CO فيها اتنين symbols، C و O","correct":true},{"id":"b","text":"أيوه، ده cobalt بحروف capital","correct":false},{"id":"c","text":"لأ، ده element جديد اسمه CO","correct":false}],"answer_t_s":92.27,"concept_id":"chem.elements-symbols"},"content_lang":"ar-EG"},{"id":"think-2","t_s":183.38,"kind":"pause_question","spec":{"answer":"element: capital واحد يعني symbol واحد (Cl)، والـ 2 atoms من نفس النوع.","prompt":"Cl₂ (chlorine): element ولا compound؟","options":[{"id":"a","text":"element","correct":true},{"id":"b","text":"compound","correct":false}],"answer_t_s":188.23,"concept_id":"chem.elements-symbols"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.elements-symbols"]},{"id":"chem-s3-en.video-walkthrough-pt.groups-periods","kind":"walkthrough","version":7,"ord":12,"content_lang":"ar-EG","primary_concept_id":"pt.groups-periods","concepts":[{"concept_id":"pt.groups-periods","role":"primary"}],"title":"Periodic table: periods and groups: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-pt.groups-periods v2 (s1 hook 'in the fourth period after calcium', Calcium (Z = 20) 2, 8, 8, 2, MCQ Period 2/4/20; s2 'arranges the elements in order of increasing atomic number', KeyTerm 'Period' (definition verbatim on the term card), caption 'Period 4: every atom here has electrons in 4 main energy levels. There are 7 periods.'; s3 '18 vertical columns', 'In the main (A) groups, the Roman numeral = the number of valence electrons', KeyTerm 'Group' (verbatim), Mg IIA (2), Cl VIIA (17), trap 'Calcium and bromine are both in period 4, so they have similar chemical properties'; s4 check 2, 8, 8, 1 (NOT reused) and true/false Na/Cl same period; s5 recap and table Mg/Cl/Ca). Concept pt.groups-periods v2 (no recorded misconceptions: s2 refutes the lesson's trap 'same period -> similar properties' (s2l14 predict, s2l15 ✕) with Ca IIA vs Br VIIA (s2l16) and the reason (s2l17)). Edition rule chem-s3-en.ch1.fact.classification applied: '18 columns' (never '18 groups'), A groups = IA-VIIA, the last column tagged '0' as a separate class, not an A group. Book: p.3 'transition elements which occupy the middle of the periodic table' (s4l3), p.4 'found in the fourth period after calcium' (s4l2). Dependents named in s4 (map titles): alloy.intermetallic 'Intermetallic alloys' (in book p.20: 'the metals are not from the same group'), pt.atomic-radius-trend 'Atomic radius trend' (across a period / down a group; direction not taught), atom.electron-configuration-writing 'Writing electronic configurations'. Terms (defined at first use): s1 element (recall, lesson wording), atomic number, periodic table (3); s2 Period, levels (recall), Group, valence electrons (recall), main (A) groups, Roman numerals. Worked example chlorine Z = 17 (2, 8, 7 -> period 3, VIIA; lesson table); self-check NEW case aluminum Z = 13 (2, 8, 3 -> period 3, group IIIA (13)), pause 4 s. Voicing: «period أربعة», «group اتنين A» / «group سبعة A» per rule chem-s3-en.voice.groups-configs (Roman numerals never read as letters). not-in-source: wall-calendar analogy (s1l2-s1l4, s2l3, s2l13); 'bromine is in group VIIA' and 'aluminum is in group IIIA (13)' (textbook-true, not in the lesson); 'Be, Mg, Ca in column IIA' (visual only). Estimated duration ≈ 4.4 min (535 words at ~2.4 words/s + 27 s of pauses).","title":"Periodic table: periods and groups: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor, stage x 790–1824: a month grid (YK.panel 1000 × 700 at (1300, 580), 7 columns of day cells, Latin digits only, no day names); day cells 1, 2, 3 light up on cues YK.cueX('s1l2','one'), 'two', 'three', then the rest of the first row fills quickly on cue 'وكده'.","tts_text":"بص على نتيجة الحيطة: الأيام مترتبة one، two، three، وكده.","screen_text":"A calendar: days in order 1, 2, 3, …","pause_after_s":0.4},{"id":"s1l3","visual":"The first row completes; a gold arrow path wraps from the end of row 1 to the start of row 2 on cue YK.cueX('s1l3','جديد'); row 2 cells fill left → right on cue 'العد'. YK.bracket around row 2 (a row).","tts_text":"ولما الأسبوع يخلص، بنبدأ صف جديد تحت، وبنكمّل العد.","screen_text":"New week → new row","pause_after_s":0.4},{"id":"s1l4","visual":"One column of the calendar glows mint top → bottom on cue YK.cueX('s1l4','الجمعات') with a small YK.icon-free glyph (a drawn sun disc, C.gold) on each of its cells on cue 'أجازة'; YK.tag 'same day' (40) over the column. The rows dim to 35%.","tts_text":"والعمود فيه نفس اليوم: الجمعات كلها تحت بعض، وكلها أجازة.","screen_text":"Same column → same day: the Fridays","pause_after_s":0.4},{"id":"s1l5","visual":"Picture change: calendar shrinks to a corner card (YK.panel 1560, 160, 300, 210) and stays as the anchor. Stage: a grid of identical YK.atomDisc(ctx, x, y, 40, {el:'Fe'}) discs on cue YK.cueX('s1l5','atoms'). Text panel YK.termCard(ctx, 96, 280, {term:'element', def:'a pure substance made of only one kind of atom', align:'left'}) on cue 'element'.","tts_text":"الـ element هو pure substance، يعني مادة نقية، الـ atoms بتاعتها من نوع واحد.","screen_text":"element: a pure substance made of only one kind of atom","pause_after_s":0.4},{"id":"s1l6","visual":"Stage: three element tiles YK.elementCard(ctx, x, 560, {sym:'H', Z:1, nameEn:'Hydrogen'}), {sym:'He', Z:2, nameEn:'Helium'}, {sym:'Li', Z:3, nameEn:'Lithium'} side by side; their Z corners pulse gold on cue YK.cueX('s1l6','رقم'). Text panel YK.termCard(ctx, 96, 280, {term:'atomic number', def:'each element has its own number', align:'left'}) on cue 'atomic'.","tts_text":"وكل element ليه رقم خاص بيه، اسمه الـ atomic number بتاعه.","screen_text":"atomic number: each element has its own number","pause_after_s":0.4},{"id":"s1l6b","visual":"YK.termCard(ctx, 96, 280, {term:'electrons', def:'tiny negative bits moving around the nucleus', align:'left'}) on cue YK.cueX('s1l6b','electrons'); stage: YK.atom(ctx, 1300, 600, {shells:[2,1], nucleusLabel:'', size:300, rotate:t}) dots appear on cue 'جسيمات', nucleus pulses on cue 'nucleus'","tts_text":"وجوه الذرة جسيمات صغيرة سالبة اسمها electrons، بتتحرك حوالين الـ nucleus، مركز الذرة.","screen_text":"electrons: tiny negative bits moving around the nucleus","pause_after_s":0.4},{"id":"s1l7","visual":"Beside the Li tile: a small YK.atom(ctx, 1300, 800, {shells:[2,1], nucleusLabel:'Li', size:200, rotate:t}) on cue YK.cueX('s1l7','neutral'); its 3 electrons glow one by one on cue 'electrons' with YK.tag '3' (the Li tile's Z 3 glows at the same time).","tts_text":"وفي الذرة الـ neutral، يعني المتعادلة، الـ atomic number هو عدد الـ electrons فيها.","screen_text":"Neutral atom: atomic number = number of electrons","pause_after_s":0.4},{"id":"s1l8","visual":"Picture change: YK.periodicTable(ctx, 820, 200, 980, {reveal:YK.prog(t, YK.cueX('s1l8','مترتبة'), YK.cueX('s1l8','periodic')), fBlock:false, labels:false}) cells pop in by Z; the corner calendar card pulses on cue 'النتيجة'. Text panel YK.termCard(ctx, 96, 280, {term:'periodic table', def:'the elements arranged in one table', align:'left'}) on cue 'periodic'.","tts_text":"والـ elements كلها مترتبة في جدول واحد اسمه الـ periodic table، زي النتيجة.","screen_text":"periodic table: the elements arranged in one table, like a calendar","pause_after_s":0.4},{"id":"s1l9","visual":"The table stays; one row and one column flash alternately (hp tween on highlight:{periods:[3]} then {groups:[2]}) on cues YK.cueX('s1l9','الصفوف') and 'والأعمدة'; a big gold '?' path at the stage corner on cue 'إزاي'.","tts_text":"طب الصفوف والأعمدة هنا معناها إيه، وبتتحدد إزاي؟","screen_text":"Rows and columns: what do they mean?","pause_after_s":1},{"id":"s2l2","visual":"Stage: YK.periodicTable(ctx, 820, 200, 980, {fBlock:false, labels:false}); a gold path snakes through the cells in Z order (row by row) from cue YK.cueX('s2l2','atomic') to 'للكبير'. Text panel YK.fpara 'Periodic table: in order of increasing atomic number' (44).","tts_text":"الـ periodic table بيرتب الـ elements بالـ atomic number، من الصغير للكبير.","screen_text":"Periodic table: in order of increasing atomic number","pause_after_s":0.4},{"id":"s2l3","visual":"Cells H, He, Li glow gold one by one on cues 'hydrogen', 'helium', 'lithium' with their Z numbers enlarged (YK.tag '1', '2', '3'); the path wraps from He (end of row 1) down to Li (start of row 2) exactly like the calendar wrap (corner calendar card repeats its wrap arrow).","tts_text":"زي أيام النتيجة: الـ hydrogen one، والـ helium two، وبعدهم الـ lithium three، وكده.","screen_text":"H 1 → He 2 → Li 3 → …","pause_after_s":0.4},{"id":"s2l4","visual":"Rows of the table glow one after another top → bottom (highlight:{periods:[1..7]} stepping) on cue YK.cueX('s2l4','period'); period numbers 1–7 appear at the left edge on cue 'seven'. Text panel YK.termCard(ctx, 96, 260, {term:'Period', def:'A horizontal row of the periodic table. The period number = the number of occupied main energy levels.', keys:['horizontal row'], align:'left'}) on cue 'period' (second sentence dim until s2l6).","tts_text":"كل صف أفقي في الـ periodic table اسمه period، وفيه seven periods في المجموع.","screen_text":"Period: a horizontal row of the periodic table · 7 periods","pause_after_s":0.4},{"id":"s2l5","visual":"Picture change: table dims to 35% on the right; YK.atom(ctx, 1100, 600, {shells:[2,8,8,2], nucleusLabel:'Ca', size:340, rotate:t}) on cue YK.cueX('s2l5','levels'); its rings light inside → out on cue 'لبرّه'.","tts_text":"وافتكر إن الـ electrons بتتحرك في levels حوالين الـ nucleus، من جوه لبرّه.","screen_text":"electrons move in levels around the nucleus","pause_after_s":0.4},{"id":"s2l6","visual":"The term card's second sentence turns bright with 'number of occupied main energy levels' gold on cue YK.cueX('s2l6','عدد'); the Ca rings get a counter tag stepping 1 → 4 (one per ring) on cue 'فعلًا'.","tts_text":"ورقم الـ period هو عدد الـ energy levels اللي فيها electrons فعلًا.","screen_text":"Period number = number of occupied energy levels","pause_after_s":0.4},{"id":"s2l7","visual":"YK.formula 'Calcium: 2, 8, 8, 2' (mono 48) builds on the spoken numbers; YK.tag '4 levels' on the atom on cue YK.cueX('s2l7','levels'); the table brightens and row 4 glows with the Ca cell gold on cue 'period' (hp 1).","tts_text":"الـ calcium two، eight، eight، two: يعني four levels، يبقى في period four أكيد.","screen_text":"Calcium: 2, 8, 8, 2 → 4 levels → period 4","pause_after_s":0.4},{"id":"s2l8","visual":"Picture change: full table again; columns glow left → right quickly on cue YK.cueX('s2l8','group'); numbers 1–18 above the columns on cue 'eighteen' ('18 columns', never '18 groups'). Text panel YK.termCard(ctx, 96, 260, {term:'Group', def:'A vertical column of the periodic table. In the main (A) groups, elements in the same group have similar properties.', keys:['vertical column'], align:'left'}) on cue 'group' (second sentence dim until s2l14).","tts_text":"والـ group عمود رأسي في الجدول، والجدول فيه eighteen عمود.","screen_text":"Group: a vertical column · the table has 18 columns","pause_after_s":0.4},{"id":"s2l9","visual":"Small YK.atom Mg (shells [2,8,2], size 260) at (1500, 760) on cue YK.cueX('s2l9','valence'); its outer ring highlighted (highlightShell:2) and its 2 dots gold on cue 'برّه'; YK.tag 'valence electrons' at the outer ring.","tts_text":"في ذرات الـ main groups، الـ valence electrons هي اللي في آخر level برّه.","screen_text":"In main groups: valence electrons = the electrons in the outermost level","pause_after_s":0.4},{"id":"s2l10","visual":"Table: the main-group columns (1, 2, 13–17) glow violet on cue YK.cueX('s2l10','main') with header tags 'IA' 'IIA' 'IIIA' … 'VIIA'; group 18 stays neutral with its own tag '0' (noble gases, a separate class, not an A group). Text panel YK.fpara 'Main (A) groups: group number = number of valence electrons' (40).","tts_text":"في الـ main groups، رقم الـ group هو عدد الـ valence electrons بتاعة الذرة.","screen_text":"Main (A) groups: group number = number of valence electrons","pause_after_s":0.4},{"id":"s2l11","visual":"Text panel: a small key YK.formula rows 'I = 1', 'II = 2', 'III = 3', '…', 'VII = 7' on cues 'one', 'two', 'three', 'seven'; the 'A' of the header tag 'IIA' pulses on cue 'حرف'. Stage table unchanged.","tts_text":"والرقم ده بيتكتب روماني: one، two، three، لحد seven، وجنبه حرف A الكبير.","screen_text":"Roman numerals: I = 1, II = 2, III = 3, …, VII = 7 (+ A)","pause_after_s":0.4},{"id":"s2l12","visual":"The Mg atom's 2 outer dots pulse on cue YK.cueX('s2l12','برّه'); table: column 2 (IIA) glows and the Mg cell turns gold on cue 'group'; YK.formula 'Magnesium: 2, 8, 2 -> IIA (2)' (mono 44).","tts_text":"الـ magnesium two، eight، two، فهو في group two A، عشان عنده two برّه.","screen_text":"Magnesium: 2, 8, 2 → group IIA (2)","pause_after_s":0.4},{"id":"s2l13","visual":"Column IIA glows top → bottom (Be, Mg, Ca, …) on cue YK.cueX('s2l13','group'); a mint YK.bracket around the column on cue 'شبه'; callback: the corner calendar's Friday column glows mint at the same time (same column → alike).","tts_text":"والـ elements اللي في نفس الـ main group، خواصها شبه بعض.","screen_text":"Same main group → similar properties","pause_after_s":0.4},{"id":"s2l14","visual":"YK.predictCard(ctx, t, {kind:'PREDICT', q:'Calcium and bromine are both in period 4. Similar properties?', at:YK.cue('s2l14'), until:YK.cue('s2l15'), think:YK.cueEnd('s2l14'), end:YK.cue('s2l15')}) (lesson trap statement); table: row 4 glows with the Ca and Br cells outlined; during the silence only the question and the think ring move.","tts_text":"توقّع: الـ calcium والـ bromine موجودين في period four. خواصهم شبه بعض؟","screen_text":"Predict: calcium and bromine are both in period 4. Similar properties?","pause_after_s":3},{"id":"s2l15","visual":"Myth beat (lesson trap / true-false): YK.mythLine(ctx, t, {at:YK.cue('s2l15'), wrongAt:YK.cueX('s2l15','غلط'), until:YK.cueEnd('s2l15')+0.4, text:'Same period → similar properties', x:96, y:300, size:48}) coral; YK.wrongMark on cue 'غلط' held for its whole visible time; row 4 flashes coral for the same time. Nothing struck through.","tts_text":"ناس كتير بتقول أيوه، عشان نفس الـ period. ده غلط.","screen_text":"Same period → similar properties","pause_after_s":0.3},{"id":"s2l16","visual":"Right model, held longer than the myth: column IIA glows cyan with Ca gold on cue YK.cueX('s2l16','calcium'); column VIIA glows amber with Br gold on cue 'bromine'; YK.tag 'IIA' and 'VIIA' at the column heads; YK.rightMark on cue 'مختلفين'.","tts_text":"الـ calcium في group two A، والـ bromine في group seven A، مختلفين.","screen_text":"Calcium: group IIA · bromine: group VIIA → different","pause_after_s":0.4},{"id":"s2l17","visual":"Table: a vertical mint arrow path down column IIA on cue YK.cueX('s2l17','group') (✓ beside it); row 4 stays plain (no ✕ on this negated sentence, no strike). Text panel YK.fpara 'In main groups: similar properties go with the same group' (40).","tts_text":"في الـ main groups، الشبه في الخواص بييجي من الـ group نفسه.","screen_text":"In main groups: similar properties go with the same group","pause_after_s":0.6},{"id":"s3l2","visual":"Stage: YK.atom(ctx, 1100, 600, {shells:[2,8,7], nucleusLabel:'Cl', size:360, rotate:t}) on cue YK.cueX('s3l2','chlorine'); its rings fill on the spoken numbers (full states only). Text panel: 3-step checklist (YK.fpara rows 'Step 1: count the levels', 'Step 2: outermost level', 'Step 3: A group', dim) under YK.formula 'Chlorine (Z = 17): 2, 8, 7' (mono 44). Small table (dim) at the stage right.","tts_text":"خد الـ chlorine: الـ atomic number seventeen، والـ electrons two، eight، seven بالترتيب.","screen_text":"Chlorine (Z = 17): 2, 8, 7 · period? group?","pause_after_s":0.3},{"id":"s3l3","visual":"Row 'Step 1' bright; the three rings get counter tags 1, 2, 3 on cue YK.cueX('s3l3','نعدّ'); on cue 'period' the small table's row 3 glows (hp 1).","tts_text":"الخطوة الأولى: نعِدّ الـ levels: three، يبقى الـ chlorine في period three أكيد.","screen_text":"Step 1: count the levels: 3 → period 3","pause_after_s":0.3},{"id":"s3l4","visual":"Row 'Step 2' bright; outer ring highlighted (highlightShell:2) on cue YK.cueX('s3l4','آخر'); its 7 dots gold on cue 'seven' (#0); YK.tag '7 valence electrons' on cue 'valence'.","tts_text":"الخطوة التانية: آخر level فيه seven، يعني seven valence electrons برّه.","screen_text":"Step 2: outermost level: 7 valence electrons","pause_after_s":0.3},{"id":"s3l5","visual":"Row 'Step 3' bright; on cue YK.cueX('s3l5','group') the small table's column 17 glows with header tag 'VIIA (17)'; row 3 and column 17 cross at the Cl cell, which turns gold.","tts_text":"الخطوة التالتة: seven valence electrons، يبقى group seven A، من الـ main groups كمان.","screen_text":"Step 3: 7 → group VIIA (17)","pause_after_s":0.3},{"id":"s3l6","visual":"YK.answerSlot(ctx, t, {at:YK.cueX('s3l6','النتيجة'), text:'Chlorine: period 3, group VIIA', x:96, y:820}) + YK.rightMark; the Cl cell pulses on cue 'مظبوط' (lesson table row: Cl 2, 8, 7, VIIA).","tts_text":"النتيجة: الـ chlorine في period three، و group seven A، مظبوط كده.","screen_text":"Chlorine: period 3, group VIIA ✓","pause_after_s":0.6},{"id":"s3l7","visual":"Picture change: the Cl result shrinks to the top of the text panel as a model; stage: YK.atom(ctx, 1100, 600, {shells:[2,8,3], nucleusLabel:'Al', size:360}) on cue YK.cueX('s3l7','aluminum'); YK.formula 'Aluminum (Z = 13): 2, 8, 3'. Table dim, nothing highlighted.","tts_text":"دورك: الـ aluminum الـ atomic number بتاعه thirteen، والـ electrons two، eight، three بالترتيب.","screen_text":"Your turn: aluminum (Z = 13): 2, 8, 3","pause_after_s":0.3},{"id":"s3l8","visual":"YK.predictCard(ctx, t, {kind:'QUICK CHECK', q:'Period? Group?', at:YK.cue('s3l8'), until:YK.cue('s3l9'), think:YK.cueEnd('s3l8'), end:YK.cue('s3l9')}) + think ring through the whole pause; the 3-step checklist re-lights dimly; during the silence ONLY the question shows (no table highlight). The Al atom (2, 8, 3) stays on the stage.","tts_text":"هو في أنهي period، وأنهي group؟ وقّف الفيديو وجرّب.","screen_text":"Period? Group?","pause_after_s":4},{"id":"s3l9","visual":"Ring counter tags 1, 2, 3 on cue YK.cueX('s3l9','levels'); table row 3 glows on cue 'period'.","tts_text":"الحل: three levels، يبقى الـ aluminum في period three أكيد.","screen_text":"3 levels → period 3","pause_after_s":0.3},{"id":"s3l10","visual":"Outer ring's 3 dots gold on cue YK.cueX('s3l10','valence'); table column 13 glows with header tag 'IIIA (13)' on cue 'group'; the Al cell at the crossing turns gold; YK.answerSlot(ctx, t, {at:YK.cueX('s3l10','group'), text:'Aluminum: period 3, group IIIA', x:96, y:820}) + YK.rightMark.","tts_text":"وفيه three valence electrons برّه، يبقى group three A، زي ما قلنا.","screen_text":"3 valence electrons → group IIIA (13) ✓","pause_after_s":0.3},{"id":"s3l11","visual":"Answer reason: on the Al atom the rings bracket together (YK.bracket) on cue YK.cueX('s3l11','levels') with an arrow path to the row; the outer dots bracket on cue 'valence' with an arrow path to the column.","tts_text":"الـ period من عدد الـ levels، والـ A group من الـ valence electrons برّه.","screen_text":"Period from the levels · A group from the valence electrons","pause_after_s":0.8},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses periods and groups' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الـ periods والـ groups دي هتقابلها فين تاني؟","screen_text":"Where periods and groups are used","pause_after_s":0.8},{"id":"s4l2","visual":"YK.periodicTable(ctx, 820, 200, 980, {highlight:{periods:[4]}, hp:YK.prog(t, YK.cueX('s4l2','period'), +0.6), fBlock:false}) ; the Ca cell glows on cue 'calcium' and the ten cells after it get a gold YK.bracket on cue 'بالظبط' (book p.4). YK.tag 'Chapter 1' (gold) on cue 'الباب'.","tts_text":"في الباب الأول، أول transition series موجودة في period four، بعد الـ calcium بالظبط.","screen_text":"Chapter 1: first transition series, period 4, after calcium","pause_after_s":0.3},{"id":"s4l3","visual":"Same table: the d-block columns (3–12) glow on cue YK.cueX('s4l3','transition') (book p.3 'occupy the middle of the periodic table'); the side columns dim. No block letters written.","tts_text":"والـ transition elements دي قاعدة في نص الـ periodic table بالظبط.","screen_text":"Transition elements: the middle of the periodic table","pause_after_s":0.3},{"id":"s4l4","visual":"YK.chip(ctx, 96, 300, 'Intermetallic alloys', {kind:'concept', align:'left'}) on cue YK.cueX('s4l4','intermetallic'); stage: two table columns glow briefly side by side on cue 'group' (no element pairs named).","tts_text":"وفي الـ intermetallic alloys، هتشوف الـ metals من نفس الـ group ولا لأ.","screen_text":"Intermetallic alloys","pause_after_s":0.3},{"id":"s4l5","visual":"YK.chip(ctx, 96, 400, 'Atomic radius trend', {kind:'concept', align:'left'}) on cue YK.cueX('s4l5','atomic'); stage: a gold arrow path along one row on cue 'period' and one down a column on cue 'group' (no direction of change shown: taught there).","tts_text":"وفي الـ atomic radius، هتشوفه بيتغير إزاي في الـ period وفي الـ group كمان.","screen_text":"Atomic radius trend","pause_after_s":0.3},{"id":"s4l6","visual":"YK.chip(ctx, 96, 500, 'Writing electronic configurations', {kind:'concept', align:'left'}) on cue YK.cueX('s4l6','electronic'); stage: the Ca cell glows with a dashed leader to the chip on cue 'بمكان'. No configuration written.","tts_text":"وفي كتابة الـ electronic configurations، هتربطها بمكان الـ element في الجدول.","screen_text":"Writing electronic configurations","pause_after_s":0.3},{"id":"s4l7","visual":"Recap (s4l7–s4l8 ≤ 20 s): YK.takeaway(ctx, {title:'Periodic table: periods and groups', line:'Period = number of levels; A group = valence electrons.', formula:'7 periods · 18 columns', t, pulse:[{word:'Period', at:YK.cueX('s4l8','period')}, {word:'group', at:YK.cueX('s4l8','group')}]}) from cue YK.cueX('s4l7','الخلاصة'); the formula line pulses on cues 'seven' and 'تمنتاشر'.","tts_text":"الخلاصة: الـ elements مترتبة بالـ atomic number، في seven periods و eighteen عمود.","screen_text":"Elements in order of increasing atomic number: 7 periods, 18 columns","pause_after_s":0.3},{"id":"s4l8","visual":"Voiced lock-in = the takeaway line 'Period = number of levels; A group = valence electrons.'; its words pulse on cues 'period', 'levels', 'group', 'valence' and stay gold; card held through the line + 1.5 s tail; last frame = the takeaway card with the full table behind it (no fade to black).","tts_text":"الـ period من عدد الـ levels، والـ A group من الـ valence electrons برّه.","screen_text":"Period = number of levels; A group = valence electrons.","pause_after_s":1.5}],"logline":"هتعرف الـ periodic table مترتب إزاي، وتلاقي الـ period والـ group لأي element من الـ electrons بتاعته.","segments":[{"id":"s1","title":"A wall calendar and the elements","concept_id":"pt.groups-periods"},{"id":"s2","title":"Periods and groups","concept_id":"pt.groups-periods"},{"id":"s3","title":"Finding the period and group of chlorine","concept_id":"pt.groups-periods"},{"id":"s4","title":"Where Chapter 1 uses periods and 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على نتيجة الحيطة الأيام مترتبة one two\nthree وكده\nولما الأسبوع يخلص بنبدأ صف جديد تحت\nوبنكمّل العد\nوالعمود فيه نفس اليوم الجمعات كلها تحت بعض\nوكلها أجازة\nالـ element هو pure substance يعني مادة\nنقية الـ atoms بتاعتها من نوع واحد\nوكل element ليه رقم خاص بيه اسمه الـ\natomic number بتاعه\nوجوه الذرة جسيمات صغيرة سالبة اسمها\nelectrons بتتحرك حوالين الـ nucleus مركز\nالذرة\nوفي الذرة الـ neutral يعني المتعادلة الـ\natomic number هو عدد الـ electrons فيها\nوالـ elements كلها مترتبة في جدول واحد\nاسمه الـ periodic table زي النتيجة\nطب الصفوف والأعمدة هنا معناها إيه وبتتحدد\nإزاي\nالـ periodic table بيرتب الـ elements بالـ\natomic number من الصغير للكبير\nزي أيام النتيجة الـ hydrogen one والـ\nhelium two وبعدهم الـ lithium three وكده\nكل صف أفقي في الـ periodic table اسمه\nperiod وفيه seven periods في المجموع\nوافتكر إن الـ electrons بتتحرك في levels\nحوالين الـ nucleus من جوه لبرّه\nورقم الـ period هو عدد الـ energy levels\nاللي فيها electrons فعلًا\nالـ calcium two eight eight two يعني four\nlevels يبقى في period four أكيد\nوالـ group عمود رأسي في الجدول والجدول فيه\neighteen عمود\nفي ذرات الـ main groups الـ valence\nelectrons هي اللي في آخر level برّه\nفي الـ main groups رقم الـ group هو عدد\nالـ valence electrons بتاعة الذرة\nوالرقم ده بيتكتب روماني one two three لحد\nseven وجنبه حرف A الكبير\nالـ magnesium two eight two فهو في group\ntwo A عشان عنده two برّه\nوالـ elements اللي في نفس الـ main group\nخواصها شبه بعض\nتوقّع الـ calcium والـ bromine موجودين في\nperiod four خواصهم شبه بعض\nناس كتير بتقول أيوه عشان نفس الـ period ده\nغلط\nالـ calcium في group two A والـ bromine في\ngroup seven A مختلفين\nفي الـ main groups الشبه في الخواص بييجي\nمن الـ group نفسه\nخد الـ chlorine الـ atomic number\nseventeen والـ electrons two eight seven\nبالترتيب\nالخطوة الأولى نعِد الـ levels three يبقى\nالـ chlorine في period three أكيد\nالخطوة التانية آخر level فيه seven يعني\nseven valence electrons برّه\nالخطوة التالتة seven valence electrons\nيبقى group seven A من الـ main groups كمان\nالنتيجة الـ chlorine في period three و\ngroup seven A مظبوط كده\nدورك الـ aluminum الـ atomic number بتاعه\nthirteen والـ electrons two eight three\nبالترتيب\nهو في أنهي period وأنهي group وقّف الفيديو\nوجرّب\nالحل three levels يبقى الـ aluminum في\nperiod three أكيد\nوفيه three valence electrons برّه يبقى\ngroup three A زي ما قلنا\nالـ period من عدد الـ levels والـ A group\nمن الـ valence electrons برّه\nطب الـ periods والـ groups دي هتقابلها فين\nتاني\nفي الباب الأول أول transition series\nموجودة في period four بعد الـ calcium\nبالظبط\nوالـ transition elements دي قاعدة في نص\nالـ periodic table بالظبط\nوفي الـ intermetallic alloys هتشوف الـ\nmetals من نفس الـ group ولا لأ\nوفي الـ atomic radius هتشوفه بيتغير إزاي\nفي الـ period وفي الـ group كمان\nوفي كتابة الـ electronic configurations\nهتربطها بمكان الـ element في الجدول\nالخلاصة الـ elements مترتبة بالـ atomic\nnumber في seven periods و eighteen عمود\nالـ period من عدد الـ levels والـ A group\nمن الـ valence electrons برّه","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":70,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":135.92,"kind":"pause_question","spec":{"answer":"لأ: الـ calcium في group IIA والـ bromine في group VIIA؛ في الـ main groups الخواص المتشابهة بتمشي مع نفس الـ group.","prompt":"الـ calcium والـ bromine الاتنين في period 4: خواصهم شبه بعض؟","options":[{"id":"a","text":"لأ، عشان مش في نفس الـ group","correct":true},{"id":"b","text":"أيوه، عشان نفس الـ period","correct":false}],"answer_t_s":139.76,"concept_id":"pt.groups-periods"},"content_lang":"ar-EG"},{"id":"think-2","t_s":202.89,"kind":"pause_question","spec":{"answer":"period 3 (تلات levels)، و group IIIA (تلاتة valence electrons).","prompt":"الـ aluminum (Z = 13): 2, 8, 3. في أنهي period وأنهي group؟","options":[{"id":"a","text":"period 3، group IIIA","correct":true},{"id":"b","text":"period 3، group IIA","correct":false},{"id":"c","text":"period 2، group IIIA","correct":false}],"answer_t_s":207.44,"concept_id":"pt.groups-periods"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-pt.groups-periods"]},{"id":"chem-s3-en.video-walkthrough-atom.sublevels","kind":"walkthrough","version":4,"ord":14,"content_lang":"ar-EG","primary_concept_id":"atom.sublevels","concepts":[{"concept_id":"atom.sublevels","role":"primary"}],"title":"Energy sublevels (s, p, d, f): from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-atom.sublevels v1 (s1 hook 'ten columns in the middle' + MCQ; s2 KeyTerm 'Energy sublevels' (The parts that a main energy level is divided into: s, p, d and f) + table n = 1–4 with sublevels and maximum electrons 2/8/18/32; s3 slider; s4 fill-blank N level / 'which sublevel does NOT exist' 2d; s5 recap: level n has n sublevels, s 2 p 6 d 10 f 14, d first at n = 3; exam callout 'd sublevel can take up to ten electrons, so the d block contains ten vertical columns'); en/ar-EG layers (trap: 'Every main energy level has all four sublevels' -> 'Level n has only n sublevels... no 2d'); concept atom.sublevels v2 summaries + misconception atom.sublevels.mc1 (refuted s2l5-s2l12: predict, myth ✕, rule ✓ scoped to n = 1–4 as the misconception text does, staircase evidence n = 1–3, 'no 2d', building callback); book Ch.1 p.3 ('Since the d-sublevel can take upto ten electrons, it contains ten vertical columns'). Dependent named in s4 (in-book): te.d-block-groups ('Main transition elements (d-block)'), only as 'd-block' + the book p.3 reason (10 columns); the map title is not written because 'main transition elements' would be 3 Latin words in a row; group names/VIII stay for the chapter. atom.orbitals (dependent, not in book) not named to avoid a new term in s4. Terms: s1 new terms = electron, main level, energy sublevels (3) (+ the everyday anchor building/floors/flats/people, Arabic only in speech). s2 = s/p/d/f sublevels (names + capacities). s3, s4 none (d-block is a chapter topic named, not taught). 'main level' used (lesson table header 'Main level') instead of 'main energy level' to keep ≤ 2 Latin words in a row; K/L/M/N letter names and the 2n² formula of the prerequisite atom.energy-levels are left out (lone Latin letters / not needed for the objectives; totals 18 and 32 are reached by adding). 'n' is shown as notation only, never spoken (the voice says «الرقم» / «رقم الـ main level»). Absolutes: rule 'main level n has n sublevels' always scoped 'n = 1 to 4' / «في أول أربع main levels» (chapter guard: 2n² only K–N; misconception text 'n = 1–4'); 'up to / at most' on every capacity; 'n = 1, 2, 3, …' on the level card. Worked example: main level 3 (3s 3p 3d, 2 + 6 + 10 = 18, lesson table); self-check NEW case: main level 4 (4 sublevels 4s 4p 4d 4f, 32 at most, lesson table/fill-blank data), pause 4.0 s, answer + reason. Predicts: s2l5 (~1:15) and s3l9 (~2:50). Estimate: 40 lines, ~487 narration words at ~2.4 w/s + 25 s pauses = ~230 s (3.8 min); recap s4l4–s4l6 ~16 s. Visuals: YK.partCard, YK.termCard, YK.predictCard, YK.mythLine + YK.wrongMark/rightMark, YK.answerSlot, YK.flyer, YK.bracket, YK.tag, YK.fpara, YK.takeaway, YK.checkPause (engine); YK.atom, YK.periodicTable (poc-science chem.js); building/staircase = page-local ctx paths + YK.panel (staircase as in chem-s3-en.video-short-atom.sublevels). not-in-source: electron defined as a tiny negative particle moving around the centre of the atom (same card as the Aufbau walkthrough); main levels counted out from the centre; the building/flats analogy (teaching device).","title":"Energy sublevels (s, p, d, f): from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor on the stage (x 790–1824): a page-local building outline (ctx paths) with three floors stacked bottom → top, each floor a YK.panel strip (w 760, h 150, accent C.gold); the floors rise in one after another on cue 'أدوار'; small door rectangles pop into the floors on cue 'شقق'. Text panel: YK.fpara 'A building: floors and flats' (48).","tts_text":"تخيّل عمارة فيها أدوار، والأدوار فيها شقق.","screen_text":"A building: floors and flats","pause_after_s":0.4},{"id":"s1l3","visual":"The floors split into flats on their cues: floor 1 keeps one flat (cue 'الأول'), floor 2 splits into two flats (cue 'شقتين'), floor 3 into three (cue 'تلات'); YK.tag 'Floor 1' / 'Floor 2' / 'Floor 3' (40) at the left edge of each floor on the same cues. Text panel: the three rows of the screen text build one per cue (YK.fpara 44).","tts_text":"إنما العمارة دي غريبة: الدور الأول فيه شقة واحدة، والتاني شقتين، والتالت تلات شقق.","screen_text":"Floor 1: 1 flat · Floor 2: 2 flats · Floor 3: 3 flats","pause_after_s":0.4},{"id":"s1l4","visual":"Picture change: four flat blocks in a row under the building (YK.panel, widths in ratio 1 : 3 : 5 : 7, y 820) each with its capacity of small people dots (C.cyan, r 10) popping in on cues 'two', 'six', 'ten', 'fourteen'; YK.tag '2', '6', '10', '14' (formula digits) under each block on the same cues. The building flats keep their widths matching these sizes (floor 1: the 2-flat; floor 2: 2 + 6; floor 3: 2 + 6 + 10).","tts_text":"والشقق مش زي بعض: شقة تشيل two، وشقة six، وشقة ten، وشقة fourteen كمان.","screen_text":"Flat sizes: 2 · 6 · 10 · 14 people","pause_after_s":0.4},{"id":"s1l5","visual":"Building slides left and shrinks to a corner (anchor stays in view). Stage: YK.atom(ctx, 1320, 580, {Z:18, size:360, rotate:t, reveal:1, nucleusLabel:''}) (centre dot unlabelled, same drawing as the Aufbau walkthrough); on cue 'electrons' the electron dots glow (colors.hl). Text panel: YK.termCard({term:'electron', def:'a tiny particle with a negative charge that moves around the centre of the atom', keys:['negative charge'], align:'left'}) on cue 'electrons'.","tts_text":"الذرة شبه العمارة دي، والسكان جواها جسيمات صغيرة سالبة اسمها electrons، حوالين المركز.","screen_text":"electron: a tiny particle with a negative charge that moves around the centre of the atom","pause_after_s":0.4},{"id":"s1l6","visual":"YK.termCard({term:'main level', def:'n = 1, 2, 3, … (counted out from the centre)', align:'left'}) on cue 'main'. Stage: YK.atom highlightShell stepping 0 → 2 on cues 'one', 'two', 'three', with YK.tag 'n = 1', 'n = 2', 'n = 3' popping on each ring on the same cues and a faint '…' tag beyond the third ring on cue 'وكده'. The corner building's floors flash in the same order (floor = main level).","tts_text":"الأدوار في الذرة اسمها main levels، ونعدّها من المركز: one، two، three، وكده.","screen_text":"main level: n = 1, 2, 3, … (counted out from the centre)","pause_after_s":0.4},{"id":"s1l7","visual":"YK.termCard({term:'energy sublevels', def:'the parts a main level is divided into', align:'left'}) on cue 'energy'. Stage: ring n = 3 of YK.atom is pulled out into a horizontal band (YK.panel 1000, 700, 760, 140) that splits into three rooms (sub-panels, widths 1 : 3 : 5) on cue 'أجزاء' — the same split as floor 3 of the building.","tts_text":"والشقق اللي جوه الدور اسمها energy sublevels، يعني أجزاء من الـ main level نفسه.","screen_text":"energy sublevels: the parts a main level is divided into","pause_after_s":0.4},{"id":"s1l8","visual":"Mapping card in the text panel: three rows (YK.fpara 44) light one per cue 'main', 'sublevel', 'electrons'; on the stage the corner building and the pulled-out band sit side by side and gold dashed leader lines join floor ↔ band, flat ↔ room, person dot ↔ electron dot on the same cues.","tts_text":"الدور هو الـ main level، والشقة هي الـ sublevel، والسكان هما الـ electrons جواها.","screen_text":"Floor = main level · flat = sublevel · people = electrons","pause_after_s":0.4},{"id":"s1l9","visual":"Stage: the band with its rooms and a big gold '?' path above it; one cyan electron dot hops room to room (deterministic sine path). Text panel: YK.fpara of the two questions (48), first on cue 'main', second on cue 'بيشيل'.","tts_text":"السؤال بقى: الـ main level فيه كام sublevel، والـ sublevel بيشيل كام electron جواه؟","screen_text":"How many sublevels in a main level? How many electrons in a sublevel?","pause_after_s":1},{"id":"s2l2","visual":"Stage: a capacity row starts (area x 820–1800, y 560–760): tile 's sublevel' (YK.panel, pink = C.s block colour of YK.periodicTable) appears on cue 'sublevel' with 2 empty dot slots that fill via YK.flyer on cue 'two'; YK.tag '2 at most' (formula '2') under it. Text panel: YK.fpara 's sublevel: 2 electrons at most' (44).","tts_text":"عندنا الـ s sublevel، شقة صغيرة بتشيل two electrons بالكتير.","screen_text":"s sublevel: 2 electrons at most","pause_after_s":0.3},{"id":"s2l3","visual":"Same row: tile 'p sublevel' (3× the s width, cyan) on cue 'sublevel'; 6 dots fill on cue 'six' (only the full state is labelled: tag '6').","tts_text":"وبعده الـ p sublevel، وبيشيل six electrons بالكتير.","screen_text":"p sublevel: 6 electrons at most","pause_after_s":0.3},{"id":"s2l4","visual":"Same row (wraps to a second line): tile 'd sublevel' (5×, violet) on cue 'd', 10 dots on cue 'ten'; tile 'f sublevel' (7×, amber) on cue 'f', 14 dots on cue 'fourteen'; tags '10' and '14' under the full tiles. The four tiles now match the four flat sizes of s1l4 (the flats shown faintly behind, then fade).","tts_text":"وكمان الـ d sublevel بيشيل ten، والـ f sublevel بيشيل fourteen كمان.","screen_text":"d sublevel: 10 · f sublevel: 14","pause_after_s":0.4},{"id":"s2l5","visual":"YK.predictCard(ctx, t, {kind:'PREDICT', q:'Does every main level have all 4 sublevels?', at:YK.cue('s2l5'), think:YK.cueEnd('s2l5'), end:YK.cue('s2l6')}); stage: the four tiles s, p, d, f hover over an empty staircase frame (three empty rows labelled 'n = 1', 'n = 2', 'n = 3'); nothing is answered during the think ring.","tts_text":"توقّع: يا ترى أي main level فيه الـ four sublevels دول؟ فكّر ثواني.","screen_text":"Predict: does every main level have all 4 sublevels?","pause_after_s":3},{"id":"s2l6","visual":"Myth beat (atom.sublevels.mc1): YK.mythLine(ctx, t, {at:YK.cue('s2l6'), wrongAt:YK.cueX('s2l6','غلط'), until:YK.cueEnd('s2l7')+1.5, text:'Every main level has all 4 sublevels', x:96, y:300, size:44}) in coral; on the stage a small coral wrong staircase (60% size) with rows n = 1 and n = 2 each drawn with four bars s p d f; YK.wrongMark on both on cue 'غلط', the ✕ held for their whole visible time; nothing struck through.","tts_text":"ناس كتير فاكرة إن أي main level فيه الـ four sublevels، وده غلط.","screen_text":"Every main level has all 4 sublevels","pause_after_s":0.4},{"id":"s2l7","visual":"Right model, bigger and held longer than the myth: text panel YK.fpara 'n = 1 to 4: main level n has n sublevels' (48, mint) + YK.rightMark on cue 'الصح'; the wrong staircase shrinks away after the myth's until; the real staircase frame (rows n = 1, 2, 3, x 900–1780, y 300–900) takes the stage, still empty.","tts_text":"الصح: في أول four main levels، الرقم هو عدد الـ sublevels جواه.","screen_text":"n = 1 to 4: main level n has n sublevels ✓","pause_after_s":0.4},{"id":"s2l8","visual":"Staircase row 'n = 1' gets one bar '1s' (pink, YK.formula label) on cue 'one'; YK.tag '1 sublevel' beside the row on cue 'one' (#1). Same staircase drawing as the concept's short (each row: number of bars = n).","tts_text":"الـ main level رقم one فيه one sublevel بس، وهو الـ one s لوحده.","screen_text":"n = 1: 1s (1 sublevel)","pause_after_s":0.3},{"id":"s2l8b","visual":"On the '1s' bar of row n = 1 the '1' pulses gold on cue 'رقم' and the 's' pulses pink on cue 'حرف'; YK.tag 'main level' under the 1 and 'sublevel' under the s on the same cues.","tts_text":"يعني الـ one s: رقم الـ main level، وبعده حرف الـ sublevel بتاعه.","screen_text":"1s = main level 1 + sublevel s","pause_after_s":0.3},{"id":"s2l9","visual":"Row 'n = 2' gets bars '2s' on cue 'two' (#0) and '2p' (3× width, cyan) on cue 'two' (#1) (YK.cueX(line,'two',1)); YK.tag '2' beside the row (bar count).","tts_text":"والـ main level رقم two فيه two: الـ two s، والـ two p برضه.","screen_text":"n = 2: 2s 2p","pause_after_s":0.3},{"id":"s2l10","visual":"Row 'n = 3' gets bars '3s', '3p', '3d' on cues 'three' (#0, #1, #2); the '3d' bar (5× width) glows violet on the last 'three'; YK.tag '3' beside the row (bar count). Staircase complete: 1, 2, 3 bars.","tts_text":"ورقم three فيه three: three s، و three p، و three d كمان.","screen_text":"n = 3: 3s 3p 3d","pause_after_s":0.4},{"id":"s2l11","visual":"On cue 'two' a dashed empty slot appears at the end of row n = 2 where a '2d' would go, labelled '2d?' in textDim, and stays EMPTY (no ✕ on this negated sentence, no strike); on cue 'three' (#0) a gold YK.bracket wraps the '3d' bar of row n = 3 with YK.tag 'first d' (40). Text panel: YK.fpara 'No 2d: the d sublevel starts at n = 3 (3d)' (44).","tts_text":"عشان كده مفيش two d، والـ d sublevel بيبدأ من الـ three d نفسه.","screen_text":"No 2d: the d sublevel starts at n = 3 (3d)","pause_after_s":0.4},{"id":"s2l12","visual":"Callback to s1: the building returns beside the staircase (picture change); floor 2 glows with its two flats on cue 'شقتين'; a ghost third flat outline tries to slide into floor 2 and bounces back off the wall on cue 'مكان' (no ✕, no strike). Rows of the staircase and floors of the building flash pairwise (floor 2 ↔ row n = 2).","tts_text":"زي العمارة بالظبط: الدور التاني فيه شقتين، ومفيش مكان لشقة تالتة.","screen_text":"Floor 2: 2 flats, no 3rd flat","pause_after_s":1},{"id":"s3l2","visual":"Stage: YK.atom(ctx, 1000, 560, {shells:[0,0,0], nucleusLabel:'', size:300, highlightShell:2}) (empty rings = the levels only, no element) with ring n = 3 gold on cue 'three'; an empty band (YK.panel) to its right waits for the sublevels. Text panel: a 4-step checklist (YK.fpara rows 'Step 1' … 'Step 4', dim) under the question (44).","tts_text":"خلّينا نفتح الـ main level رقم three، ونشوف الـ sublevels والـ electrons بتوعه.","screen_text":"Main level 3: which sublevels? How many electrons at most?","pause_after_s":0.3},{"id":"s3l3","visual":"Checklist row 'Step 1' bright on cue 'الأولى'; the band splits into three empty rooms on cue 'three' (#1); YK.formula 'n = 3 -> 3 sublevels'.","tts_text":"الخطوة الأولى: رقمه three، يبقى فيه three sublevels جواه.","screen_text":"Step 1: n = 3 → 3 sublevels","pause_after_s":0.3},{"id":"s3l4","visual":"Row 'Step 2' bright; the rooms get their labels '3s', '3p', '3d' (YK.formula, s pink / p cyan / d violet) on cues 'three' (#0, #1, #2); room widths 1 : 3 : 5.","tts_text":"الخطوة التانية: نكتبهم بالترتيب: three s، و three p، و three d كمان.","screen_text":"Step 2: 3s, 3p, 3d","pause_after_s":0.3},{"id":"s3l5","visual":"Row 'Step 3' bright; dots fly into the rooms with YK.flyer: 2 into 3s on cue 'two', 6 into 3p on cue 'six', 10 into 3d on cue 'ten'; each room's count tag ('2', '6', '10') appears only when that room is full.","tts_text":"وبعدين: three s بياخد two، والـ three p six، والـ three d ten بالكتير.","screen_text":"Step 3: 3s → 2 · 3p → 6 · 3d → 10","pause_after_s":0.3},{"id":"s3l6","visual":"Row 'Step 4' bright; YK.formula '2 + 6 + 10 = 18' builds term by term on cues 'two', 'six', 'ten', 'eighteen'; the three count tags slide down into the sum on the same cues.","tts_text":"الخطوة الرابعة: نجمع، two plus six plus ten equals eighteen electrons بالكتير.","screen_text":"Step 4: 2 + 6 + 10 = 18 electrons at most","pause_after_s":0.3},{"id":"s3l7","visual":"YK.answerSlot({text:'Main level 3: 3 sublevels, up to 18 electrons'}) + YK.rightMark on cue 'النتيجة'; the filled band snaps back onto ring n = 3 of the atom (18 dots on that ring) on cue 'eighteen'.","tts_text":"النتيجة: الـ main level رقم three فيه three sublevels، ويشيل لحد eighteen electrons بس.","screen_text":"Main level 3: 3 sublevels, up to 18 electrons ✓","pause_after_s":0.6},{"id":"s3l8","visual":"Picture change: the level-3 result shrinks to the top of the text panel as the model; stage: YK.atom(ctx, 1000, 560, {shells:[0,0,0,0], nucleusLabel:'', size:300, highlightShell:3}) on cue 'four', empty band with a '?' beside it (no rooms drawn).","tts_text":"دورك: الـ main level رقم four، فيه كام sublevel، ويشيل كام electron بالكتير؟","screen_text":"Your turn: main level 4. How many sublevels? Electrons at most?","pause_after_s":0.3},{"id":"s3l9","visual":"YK.predictCard(ctx, t, {kind:'QUICK CHECK', q:'Main level 4: how many sublevels? Electrons at most?', at:YK.cue('s3l9'), think:YK.cueEnd('s3l9'), end:YK.cue('s3l10')}) + YK.checkPause ring through the whole pause; the 4-step checklist re-lights on cue 'الأربعة'; during the silence ONLY the question shows (no rooms, no dots, no answer).","tts_text":"وقّف الفيديو، وجرّب بنفس الخطوات الأربعة قبل ما نكمّل.","screen_text":"Pause: use the same 4 steps","pause_after_s":4},{"id":"s3l10","visual":"Answer step 1: the band splits into four empty rooms on cue 'four' (#1); YK.formula 'n = 4 -> 4 sublevels'.","tts_text":"الحل: رقمه four، يبقى فيه four sublevels جواه.","screen_text":"n = 4 → 4 sublevels","pause_after_s":0.3},{"id":"s3l11","visual":"Rooms labelled '4s', '4p', '4d', '4f' on cues 'four' (#0–#3), widths 1 : 3 : 5 : 7; '4f' amber (the first f sublevel on the staircase), YK.bracket around it on cue 'four' (#3).","tts_text":"وهما four s، و four p، و four d، و four f كمان.","screen_text":"4s · 4p · 4d · 4f","pause_after_s":0.3},{"id":"s3l12","visual":"Dots fly into the four rooms (2, 6, 10, 14) on cues 'two' (#0), 'six', 'ten', 'fourteen', count tags only on full rooms; YK.answerSlot({text:'2 + 6 + 10 + 14 = 32'}) + YK.rightMark on cue 'thirty-two'.","tts_text":"نجمع: two plus six plus ten plus fourteen equals thirty-two electrons بالكتير.","screen_text":"2 + 6 + 10 + 14 = 32 electrons at most ✓","pause_after_s":0.4},{"id":"s3l13","visual":"Answer reason: the building returns small in the corner with a fourth floor drawn on top that splits into four flats on cue 'four'; its largest flat and the '4f' room pulse gold together on cue 'four'; tag '14' on cue 'fourteen'.","tts_text":"والسبب: الدور الرابع فيه أربع شقق، والرابعة هي الـ four f، بتشيل fourteen بالكتير.","screen_text":"Reason: 4f holds up to 14","pause_after_s":0.8},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الباب الأول؟","screen_text":"Where Chapter 1 uses this","pause_after_s":0.8},{"id":"s4l2","visual":"YK.periodicTable(ctx, 96, 180, 1728, {maxH:800, labels:false, highlight:{blocks:['d']}, hp:YK.prog(t, YK.cueX('s4l2','d-block'), YK.cueX('s4l2','d-block')+0.8), fBlock:false}) — the d block lights violet and the rest dims to 35% on cue 'd-block'; YK.tag 'd-block' above the block. No block-name labels other than this tag (no unspoken terms on screen).","tts_text":"في الباب الأول هتدرس جزء من الجدول الدوري اسمه الـ d-block كده.","screen_text":"d-block (Chapter 1)","pause_after_s":0.3},{"id":"s4l3","visual":"The violet 10-dot '3d' room from s3 flies onto the d block row of period 4 on cue 'sublevel'; its 10 dots drop one per column into the 10 columns (left → right, YK.flyer stagger) on cue 'ten' (#1); a counter tag '10 columns' (formula '10') and YK.tag 'book p.3' on cue 'columns'. Nothing about group names (taught in the chapter).","tts_text":"عشان الـ d sublevel بيشيل لحد ten electrons، الـ d-block فيه ten columns رأسية.","screen_text":"d sublevel holds up to 10 electrons → d-block: 10 columns (book p.3)","pause_after_s":0.5},{"id":"s4l4","visual":"Recap (≤ 20 s with s4l5–s4l6): YK.takeaway({title:'Energy sublevels (s, p, d, f)', line:'No 2d: the d sublevel starts at 3d.', formula:'s 2 · p 6 · d 10 · f 14', pulse:[{word:'Energy', at:cue 'energy'}]}) on cue 'الخلاصة'; behind it the staircase rows n = 1–3 dimmed to 35%.","tts_text":"الخلاصة: الـ energy sublevels، من الـ s sublevel لحد الـ f sublevel، four أنواع.","screen_text":"Energy sublevels (s, p, d, f)","pause_after_s":0.3},{"id":"s4l5","visual":"Takeaway card stays; a small mint line under it 'n = 1 to 4: main level n has n sublevels' fades in on cue 'main' (#0); the dimmed staircase rows flash 1, 2, 3 bars in order on cue 'عدد'.","tts_text":"وفي أول four main levels، رقم الـ main level هو عدد الـ sublevels جواه.","screen_text":"n = 1 to 4: main level n has n sublevels","pause_after_s":0.3},{"id":"s4l6","visual":"Voiced lock-in = the takeaway line 'No 2d: the d sublevel starts at 3d.'; its words pulse on cues 'two' and 'three' and stay gold; card held through the line + 1.5 s tail; last frame = the staircase with the '3d' bar bracketed (no fade to black).","tts_text":"مفيش two d، والـ d sublevel بيبدأ من الـ three d كده.","screen_text":"No 2d: the d sublevel starts at 3d.","pause_after_s":1.5}],"logline":"هتعرف الـ main level فيه كام sublevel، والـ sublevel بيشيل كام electron، وليه مفيش two d.","segments":[{"id":"s1","title":"Floors, flats and electrons","concept_id":"atom.sublevels"},{"id":"s2","title":"Which sublevels each main level has","concept_id":"atom.sublevels"},{"id":"s3","title":"The sublevels of main level 3","concept_id":"atom.sublevels"},{"id":"s4","title":"Where Chapter 1 uses 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عمارة فيها أدوار والأدوار فيها شقق\nإنما العمارة دي غريبة الدور الأول فيه شقة\nواحدة والتاني شقتين والتالت تلات شقق\nوالشقق مش زي بعض شقة تشيل two وشقة six\nوشقة ten وشقة fourteen كمان\nالذرة شبه العمارة دي والسكان جواها جسيمات\nصغيرة سالبة اسمها electrons حوالين المركز\nالأدوار في الذرة اسمها main levels ونعدّها\nمن المركز one two three وكده\nوالشقق اللي جوه الدور اسمها energy\nsublevels يعني أجزاء من الـ main level\nنفسه\nالدور هو الـ main level والشقة هي الـ\nsublevel والسكان هما الـ electrons جواها\nالسؤال بقى الـ main level فيه كام sublevel\nوالـ sublevel بيشيل كام electron جواه\nعندنا الـ s sublevel شقة صغيرة بتشيل two\nelectrons بالكتير\nوبعده الـ p sublevel وبيشيل six electrons\nبالكتير\nوكمان الـ d sublevel بيشيل ten والـ f\nsublevel بيشيل fourteen كمان\nتوقّع يا ترى أي main level فيه الـ four\nsublevels دول فكّر ثواني\nناس كتير فاكرة إن أي main level فيه الـ\nfour sublevels وده غلط\nالصح في أول four main levels الرقم هو عدد\nالـ sublevels جواه\nالـ main level رقم one فيه one sublevel بس\nوهو الـ one s لوحده\nيعني الـ one s رقم الـ main level وبعده\nحرف الـ sublevel بتاعه\nوالـ main level رقم two فيه two الـ two s\nوالـ two p برضه\nورقم three فيه three three s و three p و\nthree d كمان\nعشان كده مفيش two d والـ d sublevel بيبدأ\nمن الـ three d نفسه\nزي العمارة بالظبط الدور التاني فيه شقتين\nومفيش مكان لشقة تالتة\nخلّينا نفتح الـ main level رقم three ونشوف\nالـ sublevels والـ electrons بتوعه\nالخطوة الأولى رقمه three يبقى فيه three\nsublevels جواه\nالخطوة التانية نكتبهم بالترتيب three s و\nthree p و three d كمان\nوبعدين three s بياخد two والـ three p six\nوالـ three d ten بالكتير\nالخطوة الرابعة نجمع two plus six plus ten\nequals eighteen electrons بالكتير\nالنتيجة الـ main level رقم three فيه three\nsublevels ويشيل لحد eighteen electrons بس\nدورك الـ main level رقم four فيه كام\nsublevel ويشيل كام electron بالكتير\nوقّف الفيديو وجرّب بنفس الخطوات الأربعة\nقبل ما نكمّل\nالحل رقمه four يبقى فيه four sublevels\nجواه\nوهما four s و four p و four d و four f\nكمان\nنجمع two plus six plus ten plus fourteen\nequals thirty-two electrons بالكتير\nوالسبب الدور الرابع فيه أربع شقق والرابعة\nهي الـ four f بتشيل fourteen بالكتير\nطب الكلام ده هيفيدك فين في الباب الأول\nفي الباب الأول هتدرس جزء من الجدول الدوري\nاسمه الـ d-block كده\nعشان الـ d sublevel بيشيل لحد ten\nelectrons الـ d-block فيه ten columns\nرأسية\nالخلاصة الـ energy sublevels من الـ s\nsublevel لحد الـ f sublevel four أنواع\nوفي أول four main levels رقم الـ main\nlevel هو عدد الـ sublevels جواه\nمفيش two d والـ d sublevel بيبدأ من الـ\nthree d كده","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":71,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":76.18,"kind":"pause_question","spec":{"answer":"لأ: من n = 1 لحد n = 4، الـ main level رقم n فيه n sublevels؛ فمفيش 2d، والـ d بيبدأ من 3d.","prompt":"هل أي main level فيه الأربعة sublevels (s, p, d, f)؟","options":[{"id":"a","text":"لأ","correct":true},{"id":"b","text":"أيوه، أي main level فيه الأربعة","correct":false}],"answer_t_s":79.71,"concept_id":"atom.sublevels","misconception_id":"atom.sublevels.mc1"},"content_lang":"ar-EG"},{"id":"think-2","t_s":165.92,"kind":"pause_question","spec":{"answer":"4 sublevels (4s 4p 4d 4f)، و 2 + 6 + 10 + 14 = 32 electrons بالكتير.","prompt":"الـ main level رقم 4: كام sublevel، ويشيل كام electron بالكتير؟","options":[{"id":"a","text":"4 sublevels، 32 electrons","correct":true},{"id":"b","text":"4 sublevels، 18 electrons","correct":false},{"id":"c","text":"3 sublevels، 18 electrons","correct":false}],"answer_t_s":169.95,"concept_id":"atom.sublevels"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-atom.sublevels"]},{"id":"chem-s3-en.video-walkthrough-atom.orbitals","kind":"walkthrough","version":4,"ord":16,"content_lang":"ar-EG","primary_concept_id":"atom.orbitals","concepts":[{"concept_id":"atom.orbitals","role":"primary"}],"title":"Orbitals: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-atom.orbitals v1 (s1 hook 'Ch.1 fills the five orbitals of 3d… Why five?' + MCQ 5/10/2; s2 KeyTerm 'Orbital: The region of space around the nucleus in which the electron is most likely to be found' + s-orbital dot diagram 'the denser, the more likely'; s3 ElectronBoxes s 1 (2), p 3 (6), d 5 (10) + 'maximum electrons in a sublevel = 2 × number of orbitals'; s4 MCQ f 14 → 7 + TrueFalse orbit; s5 recap s 1 p 3 d 5 f 7, 5 × 2 = 10, exam callout p.8) and its en/ar-EG layers (trap: 'An orbital is a circular path (orbit)…' → 'We cannot trace the exact path… only the region where it is most likely… drawn as a cloud'; MCQ feedback 'one electron in each orbital' → refuted in s2l13); concept atom.orbitals v2 summaries + misconception atom.orbitals.mc1 (refuted s2l5–s2l7: myth ✕, right model ✓ cloud with reason); book Ch.1 p.8 point 1 ('gradual filling of the five orbitals of (3d) sublevel'). Dependent named in s4 (in-book): te.electron-configuration (map title 'Electronic configuration of the first transition series') + 'the five orbitals of (3d)' (p.8) only as a name; how they fill (single then pairing, Hund's rule) is left for the chapter. atom.electron-spin-pauli / atom.aufbau (dependents, not in book) are not named; s4l4 only says how two electrons share an orbital comes in the chapter (no rule stated: Pauli/spin not taught; electrons drawn as dots, never arrows). Terms: s1 new terms = nucleus, electron, sublevel (3) (+ d sublevel named with its capacity 10, needed for the hook question); s2 = orbital (+ orbit inside the myth), s and p sublevels with their capacities; s3 = f sublevel with its capacity (given in the question); s4 names chapter topics only (electronic configuration, transition series, 3d glossed as 'a d sublevel'). Absolutes: 'at most' on every capacity; 'only the region' is the lesson's own claim (we only know the region); no 'always/every' claims. Worked example: d sublevel 10 ÷ 2 = 5 orbitals (lesson hook/recap); self-check NEW case: f sublevel 14 → 7 orbitals (lesson s4 data), pause 4.0 s, answer + reason. Predicts: s2l11 p sublevel (~1:55) and s3l9 (~2:50). Estimate: 39 lines, ~412 narration words at ~2.4 w/s + 26 s pauses = ~200 s (3.3 min); recap s4l5–s4l6 ~9 s. Visuals: YK.partCard, YK.termCard, YK.predictCard, YK.mythLine + YK.wrongMark/rightMark, YK.answerSlot, YK.flyer, YK.tag, YK.fpara, YK.camera, YK.glow/glowCircle, YK.pulse, YK.takeaway, YK.checkPause, YK.chip (engine); YK.electronBoxes with electrons:0 (empty boxes, dots flown in) and YK.periodicTable (poc-science chem.js); moth/lamp and the orbital cloud = page-local ctx paths with YK.rng-seeded dots (no YK.atom rings in this video, to keep orbits out of the right model). not-in-source: the moth-around-a-lamp anchor (teaching device); nucleus = the centre of the atom; electron = tiny negative particle moving around the nucleus; sublevel defined as 'a group of places for electrons in the atom' (simplified; the sublevels lesson defines it as the parts of a main energy level).","title":"Orbitals: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor on the stage (x 790–1824, dark night background): a lamp drawn as YK.glowCircle(ctx, 1300, 520, 60, {color:C.gold}) on a short ctx-path bracket; a small moth (page-local ctx path, two wings, C.textDim) flies a fast deterministic looping path around it (sum of sines, seeded with YK.rng), entering on cue 'فراشة'. Text panel: YK.fpara 'A moth around a lamp' (48).","tts_text":"بالليل، بص على فراشة بتلِفّ حوالين لمبة البلكونة.","screen_text":"A moth around a lamp","pause_after_s":0.4},{"id":"s1l3","visual":"The moth speeds up into a blur (motion trail of 6 fading copies along its path) on cue 'بسرعة'; a dashed gold path tries to follow it and breaks into short pieces on cue 'طريقها' (no ✕: this is not a wrong idea, just a limit). Text panel: YK.fpara 'Too fast: you cannot trace its exact path' (44).","tts_text":"بتتحرك بسرعة جدًا، ومش هتقدر تحدد طريقها بالظبط.","screen_text":"Too fast: you cannot trace its exact path","pause_after_s":0.4},{"id":"s1l4","visual":"Picture change: the moth disappears; camera-flash ticks (YK.pulse) on cue 'صورتها' leave one small cyan dot per flash where the moth was (seeded YK.rng positions, radial density falling with distance from the lamp: many near, few far); about 120 dots accumulate by cue 'متجمعة'; a soft YK.glow ring marks the dense zone on cue 'جنب'.","tts_text":"إنما لو صوّرتها صور كتير، هتلاقي النقط متجمّعة جنب اللمبة.","screen_text":"Many photos: the dots crowd near the lamp","pause_after_s":0.6},{"id":"s1l5","visual":"Lamp + dot picture shrinks to the top-left of the stage (anchor stays in view). Stage centre: a nucleus drawn as YK.glowCircle(ctx, 1320, 600, 46, {color:C.pink}) (no rings, no orbit lines anywhere in this video except the myth); YK.termCard({term:'nucleus', def:'the centre of the atom', align:'left'}) on cue 'nucleus'; a gold dashed leader links the lamp to the nucleus on cue 'اللمبة'.","tts_text":"الذرة كمان ليها مركز، والمركز ده اسمه nucleus، زي اللمبة كده.","screen_text":"nucleus: the centre of the atom","pause_after_s":0.4},{"id":"s1l6","visual":"Two cyan electron dots move fast around the nucleus on a seeded jitter path (never a circle) from cue 'جسيمات'; YK.termCard({term:'electron', def:'a tiny particle with a negative charge that moves around the nucleus', keys:['negative charge'], align:'left'}) on cue 'electrons'; leader line moth ↔ electron on cue 'الفراشة'.","tts_text":"وحوالين الـ nucleus فيه جسيمات صغيرة سالبة اسمها electrons، زي الفراشة.","screen_text":"electron: a tiny particle with a negative charge that moves around the nucleus","pause_after_s":0.4},{"id":"s1l7","visual":"Stage: a row of four empty rounded trays (YK.panel, widths 1 : 3 : 5 : 7, y 820) slides in under the nucleus on cue 'مجموعات' (shapes only, no letters yet); YK.termCard({term:'sublevel', def:'a group of places for electrons in the atom', align:'left'}) on cue 'sublevels'.","tts_text":"والـ electrons جوه الذرة بتتوزّع على sublevels، يعني مجموعات.","screen_text":"sublevel: a group of places for electrons in the atom","pause_after_s":0.4},{"id":"s1l8","visual":"The third tray (5×) grows to centre stage and gets the label 'd sublevel' (YK.formula, violet) on cue 'sublevel'; ten cyan electron dots hover above it, popping in one by one and the tag '10' (formula digits) appears on cue 'ten'.","tts_text":"الـ d sublevel مثلًا بيشيل لحد ten electrons جواه.","screen_text":"d sublevel: up to 10 electrons","pause_after_s":0.4},{"id":"s1l9","visual":"The ten dots jostle above the closed d tray; a big gold '?' path above it on cue 'إزاي'. Text panel: YK.fpara 'How are 10 electrons arranged inside the d sublevel?' (48).","tts_text":"طب الـ ten electrons دول، متوزعين إزاي جوه الـ d sublevel ده؟","screen_text":"How are 10 electrons arranged inside the d sublevel?","pause_after_s":1},{"id":"s2l2","visual":"YK.termCard({term:'orbital', def:'the region of space around the nucleus in which the electron is most likely to be found', keys:['most likely'], align:'left'}) on cue 'orbital'. Stage: around the nucleus a cloud builds (soft radial gradient C.cyan + ~150 seeded dots, denser near the centre, same drawing as the lesson's s orbital diagram) from cue 'المنطقة' to cue 'موجود'.","tts_text":"الـ orbital هو المنطقة حوالين الـ nucleus، اللي الـ electron غالبًا موجود فيها.","screen_text":"orbital: the region of space around the nucleus in which the electron is most likely to be found","pause_after_s":0.4},{"id":"s2l3","visual":"Side by side: the small lamp + dots picture (left, x 900–1250) and the orbital cloud (right, x 1350–1780); both dot clouds pulse together on cue 'نقط'; YK.tag 'a region' (mint) under both on cue 'مكان'. No ✕ on this negated phrase, no strike.","tts_text":"زي نقط الفراشة حوالين اللمبة بالظبط: مكان، مش طريق.","screen_text":"Like the dots around the lamp: a region, not a path","pause_after_s":0.4},{"id":"s2l4","visual":"Zoom on the cloud (YK.camera 0.8 s): a gold probe ring sits on the dense centre on cue 'تتقل' (YK.tag 'more likely', 40) then on the thin edge (YK.tag 'less likely', textDim) on cue 'أكبر'.","tts_text":"وكل ما النقط تتقل، يبقى احتمال وجود الـ electron هناك أكبر.","screen_text":"Denser dots = more likely","pause_after_s":0.4},{"id":"s2l5","visual":"Myth beat (atom.orbitals.mc1): YK.mythLine(ctx, t, {at:YK.cue('s2l5'), wrongAt:YK.cueX('s2l5','غلط'), until:YK.cueEnd('s2l6')+1.5, text:'An orbital is a circular path (orbit)', x:96, y:300, size:44}) in coral; on the stage a small coral picture (60% size, x 900–1200): nucleus with a thin circular track and one electron sliding along it; YK.wrongMark on both on cue 'غلط', ✕ held for their whole visible time; nothing struck through.","tts_text":"ناس كتير فاكرة إن الـ orbital ده orbit، يعني مسار دايري. ده غلط.","screen_text":"An orbital is a circular path (orbit)","pause_after_s":0.4},{"id":"s2l6","visual":"Right model, bigger and held longer than the myth (x 1250–1800): the orbital cloud with the fast jittering electron dot inside it (no track) on cue 'electron'; YK.rightMark on cue 'المنطقة' + mint YK.fpara of the screen text (40) in the text panel under the myth line. No strike, no ✕ on this negated sentence.","tts_text":"إحنا مش هنقدر نحدد طريق الـ electron بالظبط، نعرف بس المنطقة الأكتر احتمال.","screen_text":"We cannot trace the electron's exact path, only the region where it is most likely ✓","pause_after_s":0.4},{"id":"s2l7","visual":"The coral circular picture exits (after the myth's until); the cloud alone holds centre stage, YK.tag 'orbital' (48) over it on cue 'orbital', a gold outline pulses round the cloud on cue 'سحابة'.","tts_text":"عشان كده بنرسم الـ orbital سحابة، مش حلقة رفيعة.","screen_text":"orbital = a cloud, not a ring ✓","pause_after_s":0.6},{"id":"s2l8","visual":"The cloud shrinks into one square box (YK.electronBoxes(ctx, 1300, 600, {boxes:1, electrons:0, size:150, label:'1 orbital'}) — empty box only; electrons are drawn as two cyan dots flown in with YK.flyer on cue 'two', no arrows: spin comes in a later lesson); a third dot arcs in and bounces off the rim on cue 'أكتر'. Tag '2 at most'.","tts_text":"وكل orbital بيشيل two electrons بالكتير، مش أكتر.","screen_text":"1 orbital: 2 electrons at most","pause_after_s":0.4},{"id":"s2l9","visual":"The trays of s1l7 come back and each turns into a row of empty boxes (YK.electronBoxes, electrons:0, gap 12) on cue 'مربعات' (counts hidden behind a soft mask until each is spoken); YK.tag '1 box = 1 orbital' on the first box on cue 'orbitals'.","tts_text":"والـ sublevel متكوّن من orbitals جنب بعض، زي صف مربعات.","screen_text":"sublevel = orbitals side by side (1 box = 1 orbital)","pause_after_s":0.4},{"id":"s2l10","visual":"First row unmasks: one box labelled 's' (pink) on cue 'sublevel'; two dots drop into it on cue 'two'; YK.formula '2 ÷ 2 = 1' under it on cue 'one'.","tts_text":"الـ s sublevel بيشيل two electrons بالكتير، يبقى فيه one orbital بس.","screen_text":"s sublevel: 2 electrons → 1 orbital","pause_after_s":0.3},{"id":"s2l11","visual":"YK.predictCard(ctx, t, {kind:'PREDICT', q:'p sublevel holds 6 electrons. How many orbitals?', at:YK.cue('s2l11'), think:YK.cueEnd('s2l11'), end:YK.cue('s2l12')}); stage: the second row stays masked with six dots hovering above it; nothing answered during the think ring.","tts_text":"توقّع: الـ p sublevel بيشيل six electrons، يبقى فيه كام orbital؟ فكّر.","screen_text":"Predict: p sublevel holds 6 electrons. How many orbitals?","pause_after_s":3},{"id":"s2l12","visual":"Answer: mask lifts on 3 boxes labelled 'p' (cyan) on cue 'three'; the six dots drop in as pairs on cue 'six' → 'اتنين'; YK.formula '6 ÷ 2 = 3' + YK.rightMark.","tts_text":"الإجابة: six divided by two equals three، يعني three orbitals بس.","screen_text":"p sublevel: 6 ÷ 2 = 3 orbitals ✓","pause_after_s":0.4},{"id":"s2l13","visual":"A ghost row of six boxes with one dot each appears faintly in textDim above the real row on cue 'six', then collapses into the real 3 boxes (pairs) on cue 'two' (no ✕ and no strike on this negated sentence; the real row stays bright and longer).","tts_text":"مش six orbitals، لأن كل orbital بياخد two electrons مع بعض.","screen_text":"Not 6 orbitals: 1 orbital takes 2 electrons","pause_after_s":1},{"id":"s3l2","visual":"Stage: the d tray of s1l8 returns with its ten hovering dots (callback to the hook) on cue 'البداية'; tag '10' on cue 'ten'. Text panel: a 3-step checklist (YK.fpara rows 'Step 1' … 'Step 3', dim) under the question (44).","tts_text":"نرجع لسؤال البداية: الـ d sublevel بيشيل ten، فيه كام orbital جواه؟","screen_text":"d sublevel: up to 10. How many orbitals?","pause_after_s":0.3},{"id":"s3l3","visual":"Row 'Step 1' bright on cue 'الأولى'; the one-box picture of s2l8 appears small beside the tray with its two dots on cue 'two'.","tts_text":"الخطوة الأولى: نفتكر إن كل orbital بيشيل two electrons بالكتير.","screen_text":"Step 1: 1 orbital → 2 electrons at most","pause_after_s":0.3},{"id":"s3l4","visual":"Row 'Step 2' bright; YK.formula '10 ÷ 2 = 5' builds term by term on cues 'ten', 'two', 'five'; the ten dots regroup into five pairs above the tray on cue 'five'.","tts_text":"الخطوة التانية: نقسم، ten divided by two equals five، وده عدد الـ orbitals كلها.","screen_text":"Step 2: 10 ÷ 2 = 5","pause_after_s":0.3},{"id":"s3l5","visual":"Row 'Step 3' bright; the tray becomes YK.electronBoxes(ctx, 1300, 620, {boxes:5, electrons:0, size:140, gap:12, label:'d'}) on cue 'مربعات'; the five pairs drop into the five boxes, one pair per box left → right (YK.flyer stagger) on cue 'two' (dots only, no arrows).","tts_text":"الخطوة التالتة: نرسم five مربعات، وفي كل مربع two electrons جواه.","screen_text":"Step 3: 5 boxes, 2 electrons in each","pause_after_s":0.3},{"id":"s3l6","visual":"YK.answerSlot({text:'d sublevel: 5 orbitals'}) + YK.rightMark on cue 'النتيجة'; YK.tag 'book p.8' on cue 'الكتاب'; the five boxes pulse one by one on cue 'five'.","tts_text":"النتيجة: الـ d sublevel فيه five orbitals، وده اللي الكتاب بيقوله.","screen_text":"d sublevel: 5 orbitals ✓ (book p.8)","pause_after_s":0.3},{"id":"s3l7","visual":"YK.formula '5 × 2 = 10' (× drawn as a path: Cairo lacks it) under the boxes; the '10' links back to the hook tag '10' with a gold arc on cue 'ten'; YK.rightMark on cue 'مظبوط'.","tts_text":"ونتأكد: five times two equals ten، مظبوط.","screen_text":"Check: 5 × 2 = 10 ✓","pause_after_s":0.6},{"id":"s3l8","visual":"Picture change: the d result shrinks to the top of the text panel as the model; stage: the widest tray labelled 'f sublevel' (amber) on cue 'sublevel' with 14 dots hovering above it on cue 'fourteen' (no boxes drawn).","tts_text":"دورك: الـ f sublevel بيشيل fourteen electrons، فيه كام orbital جواه؟","screen_text":"Your turn: f sublevel holds up to 14 electrons. How many orbitals?","pause_after_s":0.3},{"id":"s3l9","visual":"YK.predictCard(ctx, t, {kind:'QUICK CHECK', q:'f sublevel holds up to 14 electrons. How many orbitals?', at:YK.cue('s3l9'), think:YK.cueEnd('s3l9'), end:YK.cue('s3l10')}) + YK.checkPause ring through the whole pause; the 3-step checklist re-lights; during the silence ONLY the question shows (no boxes, no answer).","tts_text":"وقّف الفيديو، وجرّب بنفس الخطوات قبل ما نكمّل.","screen_text":"Pause: use the same steps","pause_after_s":4},{"id":"s3l10","visual":"YK.formula '14 ÷ 2 = 7' builds on cues 'fourteen', 'two', 'seven'; the tray becomes 7 boxes (YK.electronBoxes boxes:7, electrons:0) and the 14 dots drop in as pairs on cue 'seven'; YK.rightMark.","tts_text":"الحل: fourteen divided by two equals seven، يعني seven orbitals كلها.","screen_text":"f sublevel: 14 ÷ 2 = 7 orbitals ✓","pause_after_s":0.3},{"id":"s3l11","visual":"Answer reason: one f box zooms (YK.camera) showing its pair on cue 'two' (#0), then back; YK.formula '7 × 2 = 14' on cue 'seven'; the 7 boxes pulse once on cue 'fourteen'.","tts_text":"والسبب: كل orbital بيشيل two بالكتير، و seven times two equals fourteen بالظبط.","screen_text":"Reason: 1 orbital holds 2 at most, so 7 × 2 = 14","pause_after_s":0.8},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الباب الأول؟","screen_text":"Where Chapter 1 uses this","pause_after_s":0.8},{"id":"s4l2","visual":"YK.chip kind 'concept' 'Electronic configuration of the first transition series' (map title) slides into the text panel on cue 'transition'; stage: YK.periodicTable(ctx, 820, 200, 1000, {maxH:560, labels:false, fBlock:false, highlight:{symbols:['Sc','Ti','V','Cr','Mn','Fe','Co','Ni','Cu','Zn']}, hp:YK.prog(t, YK.cueX('s4l2','transition'), YK.cueX('s4l2','transition')+0.8)}) — the ten cells of period 4 in the d block glow, the rest dims to 35%. No configurations written (taught in the chapter).","tts_text":"أول transition series في الباب الأول، هتكتب الـ electronic configuration بتاعها.","screen_text":"Chapter 1: Electronic configuration of the first transition series","pause_after_s":0.3},{"id":"s4l3","visual":"The five-box d row from s3 slides under the glowing strip and gets the label '3d' (YK.formula, violet) on cue 'three'; YK.tag 'book p.8' on cue 'الكتاب'; the five boxes pulse on cue 'five' (boxes shown empty: how they fill is the chapter's).","tts_text":"الـ three d ده d sublevel، يعني فيه five orbitals، زي ما الكتاب بيقول.","screen_text":"3d = a d sublevel: 5 orbitals (book p.8)","pause_after_s":0.3},{"id":"s4l4","visual":"One box zooms with its two cyan dots (no arrows) on cue 'electrons'; a small gold '?' tag 'more in the chapter' on cue 'الباب'. No spin, no arrows, no rule stated.","tts_text":"والـ two electrons اللي في كل orbital، هتعرف بيقعدوا إزاي في الباب.","screen_text":"2 electrons in 1 orbital: more in the chapter","pause_after_s":0.5},{"id":"s4l5","visual":"Recap (≤ 20 s with s4l6): YK.takeaway({title:'Orbitals', line:'1 orbital: 2 electrons at most.', formula:'s 1 · p 3 · d 5 · f 7', pulse:[{word:'Orbitals', at:cue 'orbitals'}]}) on cue 'الخلاصة'; behind it the orbital cloud (dimmed 35%), not a ring.","tts_text":"الخلاصة: الـ orbitals مناطق حوالين الـ nucleus، مش مسارات دايرية.","screen_text":"Orbitals","pause_after_s":0.3},{"id":"s4l6","visual":"Voiced lock-in = the takeaway line '1 orbital: 2 electrons at most.'; '2 electrons' pulses gold on cue 'two' and stays; card held through the line + 1.5 s tail; last frame = the cloud with the takeaway (no fade to black).","tts_text":"كل orbital بيشيل two electrons بالكتير.","screen_text":"1 orbital: 2 electrons at most.","pause_after_s":1.5}],"logline":"هتعرف يعني إيه orbital، وليه مش مسار دايري، وتحسب الـ sublevel فيه كام orbital من عدد الـ electrons اللي بيشيلها.","segments":[{"id":"s1","title":"Nucleus, electrons, sublevels","concept_id":"atom.orbitals"},{"id":"s2","title":"What an orbital is, and how many","concept_id":"atom.orbitals"},{"id":"s3","title":"Count the orbitals of a sublevel","concept_id":"atom.orbitals"},{"id":"s4","title":"Where Chapter 1 uses 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بص على فراشة بتلِف حوالين لمبة\nالبلكونة\nبتتحرك بسرعة جدًا ومش هتقدر تحدد طريقها\nبالظبط\nإنما لو صوّرتها صور كتير هتلاقي النقط\nمتجمّعة جنب اللمبة\nالذرة كمان ليها مركز والمركز ده اسمه\nnucleus زي اللمبة كده\nوحوالين الـ nucleus فيه جسيمات صغيرة سالبة\nاسمها electrons زي الفراشة\nوالـ electrons جوه الذرة بتتوزّع على\nsublevels يعني مجموعات\nالـ d sublevel مثلًا بيشيل لحد ten\nelectrons جواه\nطب الـ ten electrons دول متوزعين إزاي جوه\nالـ d sublevel ده\nالـ orbital هو المنطقة حوالين الـ nucleus\nاللي الـ electron غالبًا موجود فيها\nزي نقط الفراشة حوالين اللمبة بالظبط مكان\nمش طريق\nوكل ما النقط تتقل يبقى احتمال وجود الـ\nelectron هناك أكبر\nناس كتير فاكرة إن الـ orbital ده orbit\nيعني مسار دايري ده غلط\nإحنا مش هنقدر نحدد طريق الـ electron\nبالظبط نعرف بس المنطقة الأكتر احتمال\nعشان كده بنرسم الـ orbital سحابة مش حلقة\nرفيعة\nوكل orbital بيشيل two electrons بالكتير مش\nأكتر\nوالـ sublevel متكوّن من orbitals جنب بعض\nزي صف مربعات\nالـ s sublevel بيشيل two electrons بالكتير\nيبقى فيه one orbital بس\nتوقّع الـ p sublevel بيشيل six electrons\nيبقى فيه كام orbital فكّر\nالإجابة six divided by two equals three\nيعني three orbitals بس\nمش six orbitals لأن كل orbital بياخد two\nelectrons مع بعض\nنرجع لسؤال البداية الـ d sublevel بيشيل\nten فيه كام orbital جواه\nالخطوة الأولى نفتكر إن كل orbital بيشيل\ntwo electrons بالكتير\nالخطوة التانية نقسم ten divided by two\nequals five وده عدد الـ orbitals كلها\nالخطوة التالتة نرسم five مربعات وفي كل\nمربع two electrons جواه\nالنتيجة الـ d sublevel فيه five orbitals\nوده اللي الكتاب بيقوله\nونتأكد five times two equals ten مظبوط\nدورك الـ f sublevel بيشيل fourteen\nelectrons فيه كام orbital جواه\nوقّف الفيديو وجرّب بنفس الخطوات قبل ما\nنكمّل\nالحل fourteen divided by two equals seven\nيعني seven orbitals كلها\nوالسبب كل orbital بيشيل two بالكتير و\nseven times two equals fourteen بالظبط\nطب الكلام ده هيفيدك فين في الباب الأول\nأول transition series في الباب الأول هتكتب\nالـ electronic configuration بتاعها\nالـ three d ده d sublevel يعني فيه five\norbitals زي ما الكتاب بيقول\nوالـ two electrons اللي في كل orbital\nهتعرف بيقعدوا إزاي في الباب\nالخلاصة الـ orbitals مناطق حوالين الـ\nnucleus مش مسارات دايرية\nكل orbital بيشيل two electrons بالكتير","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":72,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":105.2,"kind":"pause_question","spec":{"answer":"3 orbitals: 6 ÷ 2، لأن الـ orbital الواحد بياخد 2 electrons بالكتير.","prompt":"الـ p sublevel بيشيل 6 electrons: فيه كام orbital؟","options":[{"id":"a","text":"3","correct":true},{"id":"b","text":"6","correct":false},{"id":"c","text":"2","correct":false}],"answer_t_s":109.15,"concept_id":"atom.orbitals"},"content_lang":"ar-EG"},{"id":"think-2","t_s":167.19,"kind":"pause_question","spec":{"answer":"7 orbitals: 14 ÷ 2 = 7.","prompt":"الـ f sublevel بيشيل 14 electrons: فيه كام orbital؟","options":[{"id":"a","text":"7","correct":true},{"id":"b","text":"14","correct":false},{"id":"c","text":"5","correct":false}],"answer_t_s":171.2,"concept_id":"atom.orbitals"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-atom.orbitals"]},{"id":"chem-s3-en.video-walkthrough-atom.aufbau","kind":"walkthrough","version":5,"ord":18,"content_lang":"ar-EG","primary_concept_id":"atom.aufbau","concepts":[{"concept_id":"atom.aufbau","role":"primary"}],"title":"Aufbau principle (order of filling): from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-atom.aufbau v3 (steps s1 hook Ca electrons 19/20, s2 Aufbau term + filling order + diagonal diagram cut at 4p, s3 Ar->V, s4 Ga fill-blank, s5 recap/exam callout); concept atom.aufbau v2 + misconceptions mc1 (3 < 4, refuted s2l13-s2l17 with K/Ca/Sc evidence) and mc2 (filled first = lost last, refuted s2l21-s2l25 with the book's V flowchart p.9 and 'outermost level, n = 4'); book Ch.1 p.4 (first transition series: 3d filled successively after Ca, Sc 4s2 3d1 to Zn 4s2 3d10), p.8 (Ca [Ar] 4s2; table: Sc [Ar] 4s2 3d1, V [Ar] 4s2 3d3, Fe [Ar] 4s2 3d6; Cr/Cu anomalous), p.9 (V loses 4s first: V 4s2 3d3 -> V+ 4s1 3d3 -> V2+ 4s0 3d3; statement 3: +2 after losing 4s). Dependents named in s4: te.electron-configuration (first transition series), te.cr-cu-anomaly (map title 'Abnormal electronic configuration of chromium and copper'), te.ion-configuration ('Ions: 4s electrons are lost first'), via atom.electron-configuration-writing. DB rules applied: configurations in book order [Ar] 4s^x 3d^y; no empty 3d drawn for K/Ca (3d tile first appears at Sc); no intermediate fill labels; no energy statement anywhere (order given with K/Ca/Sc evidence, removal reason = outermost level n = 4); 'electronic configuration' (book term); 'Usually' scopes the fill-then-move rule (Cr/Cu named in s4); 4s-loses-first scoped to 4s vs 3d / the series atoms (Ga loses 4p first); no orbitals/boxes/Pauli/Hund (not needed by the lesson). Terms: s1 new terms = electron, level, sublevel (3); s2 = atomic number, Aufbau principle, electronic configuration ([Ar] notation); s3 none; s4 names chapter topics only (transition series, abnormal). 'level' used as in the DB rule wording 'outermost level (n = 4)' rather than 'main energy level' (3 Latin words in a row). Worked example Fe (book table p.8); self-check NEW case Ga (Z = 31, lesson s4 data) with pause 4.0 s, answer + reason. Predicts: s2l12 (~1:40) and s3l11 (~3:50). Estimate: 59 lines, 671 narration words at ~2.4 w/s + 31 s pauses = ~320 s (5.3 min; recap s4l5-s4l7 ~15 s). not-in-source: 'Aufbau' is German for 'building up' (lesson says 'building-up principle'); electron defined as a tiny negative particle moving around the centre of the atom; levels n = 1..4 counted out from the centre; Z = number of electrons in the atom; s/p/d sublevels hold at most 2/6/10 (concept atom.sublevels); K [Ar] 4s1 and Ga [Ar] 4s2 3d10 4p1 (lesson, not the book).","title":"Aufbau principle (order of filling): from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor on the stage: an address card YK.panel(1000, 300, 640, 420, {accent:C.gold}) with two YK.label rows 'Building: 4' then 'Flat: s' (Cairo 800, 56); 'Building: 4' slides in on cue 'العمارة', 'Flat: s' on cue 'الشقة'. Text panel: YK.fpara 'Address = building number + flat' (44).","tts_text":"لو هتطلب أكل دليفري، لازم تكتب رقم العمارة ورقم الشقة.","screen_text":"Address = building number + flat","pause_after_s":0.4},{"id":"s1l3","visual":"Address card slides left and shrinks to a corner (keeps the anchor in view). Stage: YK.atom(ctx, 1300, 580, {Z:20, size:380, rotate:t, reveal:1, nucleusLabel:''}) (centre dot unlabeled); on cue 'electrons' the electron dots glow (YK.atom colors.hl). Text panel: YK.termCard({term:'electron', def:'a tiny particle with a negative charge that moves around the centre of the atom', keys:['negative charge'], align:'left'}) on cue 'electrons'.","tts_text":"جوه الذرة فيه جسيمات صغيرة سالبة اسمها electrons، بتتحرك حوالين المركز.","screen_text":"electron: a tiny particle with a negative charge that moves around the centre of the atom","pause_after_s":0.4},{"id":"s1l4","visual":"The address card returns beside the atom: one electron dot of YK.atom (outer ring) gets a gold YK.bracket on cue 'عنوان' and a dashed leader line to the card; the card's two rows turn into two empty slots '__' '__' on cue 'حاجتين' (picture change).","tts_text":"والـ electron كمان ليه عنوان زي عنوانك بالظبط، من حاجتين.","screen_text":"An electron has an address too","pause_after_s":0.3},{"id":"s1l5","visual":"YK.termCard({term:'level', def:'n = 1, 2, 3, 4, … (counted out from the centre)'}) on cue 'level'. Stage: YK.atom with highlightShell stepping 0→3; a YK.tag 'n = 1' … 'n = 4' pops on each ring on cues 'واحد', 'اتنين', 'تلاتة', 'أربعة' (formula labels '1','2','3','4'). Card slot 1 fills with 'level' (gold).","tts_text":"الحاجة الأولى الـ level، وده زي رقم العمارة: one، two، three، four، وكده.","screen_text":"level: n = 1, 2, 3, 4, … (counted out from the centre)","pause_after_s":0.4},{"id":"s1l6","visual":"YK.termCard({term:'sublevel', def:'a part of a level'}) on cue 'sublevel'. Stage: the ring n = 4 of YK.atom is pulled out into a horizontal band (YK.panel 1000, 700, 760, 140) that splits into small rooms (sub-panels) on cue 'الشقة'. Card slot 2 fills with 'sublevel' (violet).","tts_text":"الحاجة التانية الـ sublevel، وده زي الشقة جوه العمارة.","screen_text":"sublevel: a part of a level","pause_after_s":0.4},{"id":"s1l7","visual":"Stage: big YK.formula '4s' (mono 120) centred; on cue 'four' the '4' turns gold with a YK.tag 'level' under it; on cue 'sublevel' the 's' turns violet with a YK.tag 's sublevel' under it. Address card ('Building: 4 / Flat: s') morphs into '4s' at the same time (anchor → notation).","tts_text":"يعني four s معناها الـ s sublevel اللي في level four بالظبط.","screen_text":"4s = level 4, the s sublevel","pause_after_s":0.4},{"id":"s1l8","visual":"Three capacity tiles appear one per line (YK.flow layout 'row', area x 820–1800, y 560–760): tile 's sublevel' on cue 'sublevel' with 2 cyan dot slots that fill via YK.flyer on cue 'اتنين'; YK.tag '2 at most' (formula '2').","tts_text":"الـ s sublevel بيشيل two electrons بالكتير، زي شقة صغيرة.","screen_text":"s sublevel: 2 electrons at most","pause_after_s":0.3},{"id":"s1l9","visual":"Same YK.flow row: tile 'p sublevel' (3× the s tile width) appears on cue 'p' and gets its 6 dots on cue 'ستة'; tile 'd sublevel' (5×) on cue 'd' and gets its 10 dots on cue 'عشرة'; final tags '6' and '10' under the tiles (only full states shown).","tts_text":"والـ p sublevel بيشيل six، والـ d sublevel بيشيل ten كمان.","screen_text":"p sublevel: 6 · d sublevel: 10","pause_after_s":0.4},{"id":"s1l10","visual":"Back to the big formula slot: YK.formula '3d' (mono 120) builds like s1l7: '3' gold + tag 'level' on cue 'three', 'd' violet + tag 'd sublevel' on cue 'sublevel'. The 4s formula sits small beside it (both addresses on screen, setting up the question).","tts_text":"وبنفس الطريقة، three d معناها الـ d sublevel اللي في level three بالظبط.","screen_text":"3d = level 3, the d sublevel","pause_after_s":0.4},{"id":"s1l11","visual":"Stage: the two formulas '4s' and '3d' side by side with one cyan electron dot bouncing between them (deterministic sine path, as in the short's frame 0); a big gold '?' path above. Text panel: YK.fpara 'In what order do electrons fill the sublevels?' (48).","tts_text":"دلوقتي السؤال المهم: الـ electrons بتسكن الـ sublevels دي بأي ترتيب؟","screen_text":"In what order do electrons fill the sublevels?","pause_after_s":1},{"id":"s2l2","visual":"YK.termCard({term:'atomic number (Z)', def:'in the atom, Z = the number of electrons'}) on cue 'atomic'. Stage: YK.elementCard({sym:'Ar', Z:18, nameEn:'Argon', config:''}) at (1300, 560), its Z corner pulses gold on cue 'عدد'.","tts_text":"أي عنصر ليه atomic number، وده هو عدد الـ electrons في الذرة.","screen_text":"atomic number (Z): in the atom, Z = the number of electrons","pause_after_s":0.3},{"id":"s2l3","visual":"Formula '_{18}Ar: 18 electrons'. Stage: the sublevel ladder appears empty to the right of the Argon card (sublevel ladder = YK.flow({layout:'col', area:{x:1180,y:150,w:420,h:850}, node:{size:40,minW:200}}) with nodes 1s 2s 2p 3s 3p 4s 3d 4p (formula labels, sub = capacity counter, written only once a tile is full or final; never an intermediate count), electrons = cyan dots (r 12) flown in with YK.flyer and parked inside the node rect); only tiles 1s–3p are shown, the remaining tiles are hidden (no 4s/3d yet). A YK.tag '18' on the card on cue 'تمنتاشر' (first).","tts_text":"الـ argon مثلًا الـ atomic number بتاعه eighteen، فيه eighteen electrons جواه.","screen_text":"Argon ₁₈Ar: 18 electrons","pause_after_s":0.3},{"id":"s2l4","visual":"YK.termCard({term:'Aufbau principle', def:'electrons fill the sublevels one after another, in a fixed order, starting with 1s', keys:['fixed order']}) on cue 'Aufbau'. Ladder: tile 1s glows gold (start) on cue 'ثابت'. No axis and no ranking words on the ladder (brief rule).","tts_text":"القاعدة اسمها Aufbau principle: الـ electrons بتملا الـ sublevels بترتيب ثابت.","screen_text":"Aufbau principle: electrons fill the sublevels one after another, in a fixed order, starting with 1s","pause_after_s":0.3},{"id":"s2l5","visual":"YK.tag 'Aufbau = building up' (gold, 44) under the term card on cue 'بناء'; stage: a short stack of electron dots drops into the 1s tile one by one on cue 'بنبني' (YK.flyer, 2 dots), tile counter shows '2' only when full.","tts_text":"كلمة Aufbau ألماني ومعناها بناء، يعني بنبني الذرة حتة حتة.","screen_text":"Aufbau = building up","pause_after_s":0.3},{"id":"s2l6","visual":"Ladder: tiles fill on their cues: 1s already full; 2s gets 2 dots on cue 'two' (#0), 2p gets 6 dots on cue 'two' (#1) (YK.cueX(line,'two',1)); YK.flow edges light 1s→2s→2p on the same cues. Text panel formula '1s -> 2s -> 2p' builds in step.","tts_text":"الترتيب بيبدأ كده: one s، وبعدين two s، وبعدين two p، طبيعي.","screen_text":"1s → 2s → 2p","pause_after_s":0.2},{"id":"s2l7","visual":"Ladder: 3s fills (2 dots) on cue 'three' (#0), 3p fills (6 dots) on cue 'three' (#1); on cue 'اكتمل' the Argon card glows mint and a YK.tag '18' sits next to the five full tiles (the counts 2+2+6+2+6 add up on the tiles).","tts_text":"وبعدين three s، وبعدها three p، وكده الـ argon اكتمل.","screen_text":"→ 3s → 3p = [Ar]","pause_after_s":0.3},{"id":"s2l8","visual":"The five full tiles collapse (YK.tween, outBack) into one core chip YK.chip '[Ar]' at the top of the ladder on cue 'بنختصره'; text panel YK.formula '[Ar] = 1s^2 2s^2 2p^6 3s^2 3p^6' (mono 44) appears on cue 'argon' with '[Ar]' gold.","tts_text":"وبدل ما نكتب ده تاني، بنختصره ونكتب argon بين قوسين.","screen_text":"[Ar] = 1s² 2s² 2p⁶ 3s² 3p⁶","pause_after_s":0.3},{"id":"s2l9","visual":"YK.termCard({term:'electronic configuration', def:'where the electrons of an atom are, sublevel by sublevel'}) on cue 'electronic'. The formula '[Ar] = 1s^2 2s^2 2p^6 3s^2 3p^6' stays above it; each label gets a thin gold underline left→right on cue 'العناوين' (the address idea from s1).","tts_text":"الكتابة دي اسمها electronic configuration، يعني توزيع الـ electrons على العناوين.","screen_text":"electronic configuration: where the electrons of an atom are, sublevel by sublevel","pause_after_s":0.3},{"id":"s2l10","visual":"Zoom on the term '3p^6' of the formula (YK.bracket around it on cue 'الصغير'); the superscript 6 pulses gold on cue 'ستة' (#0) and an arc arrow path points from it to the 6 dots of the 3p tile (shown again briefly) on cue 'ستة' (#1). Formula '3p^6 = 6 electrons in 3p'.","tts_text":"الرقم الصغير فوق هو عدد الـ electrons، يعني three p six: six هناك.","screen_text":"3p⁶ = 6 electrons in 3p","pause_after_s":0.4},{"id":"s2l11","visual":"Stage: YK.elementCard({sym:'K', Z:19, nameEn:'Potassium', config:''}) replaces the Argon card on cue 'potassium'; formula '_{19}K: 19 = 18 + 1' builds on cue 'تسعتاشر' and 'واحد'. One new cyan dot hovers above the ladder under the '[Ar]' chip. Tiles 4s and 3d are NOT drawn yet.","tts_text":"طب الـ potassium عنده nineteen electrons، يعني one زيادة عن الـ argon بالظبط.","screen_text":"Potassium ₁₉K: 19 electrons = 18 + 1","pause_after_s":0.3},{"id":"s2l12","visual":"YK.predictCard({kind:'PREDICT', q:'Electron 19 -> 3d or 4s?', at:YK.cue('s2l12'), think:YK.cueEnd('s2l12'), end:YK.cue('s2l13')}): only the question + think ring during the silence; stage: the hovering dot sways between two closed doors labelled '3d' and '4s' (YK.panel tiles, no fill state).","tts_text":"توقّع: الـ electron ده يروح three d ولا four s؟ فكّر ثواني.","screen_text":"Predict: electron 19 → 3d or 4s?","pause_after_s":3},{"id":"s2l13","visual":"Myth beat (mc1): YK.mythLine({text:'3d first, because 3 < 4', wrongAt:YK.cueX('s2l13','غلط')}) in coral at the top of the text panel, plus a small static coral column '3p -> 3d -> 4s' (60% size) on the stage; YK.wrongMark on both on cue 'غلط' and the ✕ stays for their whole visible time; both exit 0.4 s after the line. Nothing struck through.","tts_text":"ناس كتير بتقول three d، عشان three أصغر من four. ده غلط.","screen_text":"3d first, because 3 < 4","pause_after_s":0.3},{"id":"s2l14","visual":"Right model, bigger and held longer than the myth: the 4s tile appears under '[Ar]' on cue 'four' (#0) and the hovering dot flies into it (YK.flyer) on cue 'واحد'; YK.rightMark + YK.answerSlot({text:'_{19}K: [Ar] 4s^1'}) on the same cue. The 3d tile is still not drawn (no empty 3d for K).","tts_text":"الإجابة four s: الـ potassium هو argon، والـ four s فيها one بس.","screen_text":"Potassium ₁₉K: [Ar] 4s¹ ✓","pause_after_s":0.4},{"id":"s2l15","visual":"YK.elementCard Ca (Z 20, nameEn 'Calcium', config '') on cue 'calcium'; a second dot flies into the 4s tile on cue 'four'; the 4s tile turns mint with tag 'full' on cue 'ويقفلها'; formula '_{20}Ca: [Ar] 4s^2' (book p.8 wording). Still no 3d tile.","tts_text":"والـ calcium عنده twenty، فالتاني برضه بيروح الـ four s ويقفلها.","screen_text":"Calcium ₂₀Ca: [Ar] 4s²","pause_after_s":0.4},{"id":"s2l16","visual":"The 3d tile appears below 4s on cue 'scandium' (first time on screen), one dot arcs into it on cue 'three'; formula '_{21}Sc: [Ar] 4s^2 3d^1' (book p.4/p.8, book order 4s then 3d) + YK.rightMark. The three cards K, Ca, Sc line up as a mini table (formulas '[Ar] 4s^1', '[Ar] 4s^2', '[Ar] 4s^2 3d^1').","tts_text":"وبعد الـ calcium، الـ scandium بيحط أول electron في الـ three d أخيرًا.","screen_text":"Scandium ₂₁Sc: [Ar] 4s² 3d¹","pause_after_s":0.4},{"id":"s2l17","visual":"Refutation with its reason: the K/Ca/Sc mini table stays; YK.bracket around the '4s' column of K and Ca on cue 'level' (evidence), text panel YK.fpara 'The level number alone does not set the order' (no strike, no ✕ on this negated sentence; a mint ✓ beside the K/Ca/Sc table instead).","tts_text":"يعني رقم الـ level لوحده مش هو اللي بيحدد الترتيب.","screen_text":"The level number alone does not set the order","pause_after_s":0.4},{"id":"s2l18","visual":"Full ladder visible: '[Ar]' chip expands back into 1s…3p tiles, then 4s, 3d and a faint 4p tile below; YK.flow edges 3p→4s→3d→4p light on cues 'three' (#0), 'four' (#0), 'three' (#1), 'four' (#1). Text panel formula '1s 2s 2p 3s 3p 4s 3d 4p' with 4s gold and 3d violet.","tts_text":"الترتيب: three p، وبعدين four s، وبعدين three d، وبعدين four p في الآخر.","screen_text":"Order of filling: 1s 2s 2p 3s 3p 4s 3d 4p","pause_after_s":0.4},{"id":"s2l19","visual":"Memory aid (lesson step 2 diagram, cut at 4p): YK.flow with explicit node x/y in a grid on the stage: row 1: 1s; row 2: 2s 2p; row 3: 3s 3p 3d; row 4: 4s 4p; dashed diagonal edges (top-right to bottom-left) drawn in order 1s | 2s | 2p→3s | 3p→4s | 3d→4p on cue 'امشي' (reveal over ~2 s); each node flashes in filling order.","tts_text":"وعشان تفتكره بسهولة، امشي على الأسهم المايلة دي من فوق لتحت.","screen_text":"Diagonal arrows give the order","pause_after_s":0.4},{"id":"s2l20","visual":"Ladder: a dot stream fills 4s to full, then moves to 3d (counter shown only on full tiles); text panel YK.fpara 'Usually: fill a sublevel, then move on to the next' with 'Usually' gold (scoped: Cr and Cu come in s4).","tts_text":"وفي العادي، الـ sublevel بيتمِلي، وبعدين ننقل للي عليه الدور.","screen_text":"Usually: fill a sublevel, then move on to the next","pause_after_s":0.4},{"id":"s2l21","visual":"Before the split stage: a small YK.atom (Z:23) drops one outer dot that flies away with a coral trail on cue 'تخسر'. Then picture change: split stage, left header YK.tag 'Filling' (cyan) with dots flying IN to the 4s and 3d tiles, right header YK.tag 'Losing' (coral) with an empty arrow path; text panel YK.fpara 'Filling order vs losing order'.","tts_text":"وخلّي بالك: الذرة ممكن كمان تِخسر electrons، وترتيب الخروج غير ترتيب الملء.","screen_text":"Filling order vs losing order","pause_after_s":0.3},{"id":"s2l22","visual":"Myth beat (mc2): YK.mythLine({text:'Filled first = lost last', wrongAt:YK.cueX('s2l22','غلط')}) coral + YK.wrongMark on cue 'غلط', ✕ held for its whole visible time; exits 0.4 s after the line.","tts_text":"ناس بتفتكر إن اللي اتملى الأول، هو آخر واحد يخرج. ده غلط.","screen_text":"Filled first = lost last","pause_after_s":0.3},{"id":"s2l23","visual":"Right model, held longer than the myth: Vanadium tiles from the ladder style: '[Ar]' chip + 4s tile (2 dots) + 3d tile (3 dots), formula '[Ar] 4s^2 3d^3'; on cue 'بيخسر' the two 4s dots fly up-right with a cyan trail (YK.flyer) while the 3d dots stay; YK.rightMark. The empty 4s tile is faded out, not labelled 4s^0 (zeros hidden).","tts_text":"بين الـ four s والـ three d، الـ four s هو اللي بيخسر الأول.","screen_text":"Losing electrons: 4s loses before 3d ✓","pause_after_s":0.3},{"id":"s2l24","visual":"YK.elementCard({sym:'V', Z:23, nameEn:'Vanadium', config:'[Ar] 4s^2 3d^3'}) beside the tiles on cue 'vanadium'; the removal from s2l23 replays once on cue 'بيخرجوا' with YK.tag 'book p.9' (formula '2'). No ion symbol, no kJ values.","tts_text":"زي الـ vanadium في الكتاب: أول two electrons بيخرجوا من الـ four s الأول.","screen_text":"Vanadium: [Ar] 4s² 3d³ → the two 4s electrons leave first (book p.9)","pause_after_s":0.3},{"id":"s2l25","visual":"Callback to s1: YK.atom(…, {Z:23, size:300, highlightShell:3}) with ring n = 4 gold and a YK.tag 'n = 4 (outermost)' on cue 'الخارجي'; text panel YK.fpara 'Why: 4s is in the outermost level (n = 4)'.","tts_text":"والسبب إن الـ four s في الـ level الخارجي، رقمه four أصلًا.","screen_text":"Why: 4s is in the outermost level (n = 4)","pause_after_s":1},{"id":"s3l2","visual":"Stage: YK.elementCard({sym:'Fe', Z:26, nameEn:'Iron', config:''}) at (1000, 300) on cue 'iron'; empty ladder ('[Ar]' chip slot, 4s, 3d tiles) to its right. Text panel: a 4-step checklist (YK.fpara rows 'Step 1' … 'Step 4', dim) and the question formula '_{26}Fe: ?' on cue 'ستة'.","tts_text":"الـ iron الـ atomic number بتاعه twenty-six، خلّينا نكتب الـ electronic configuration بتاعه.","screen_text":"Iron ₂₆Fe (Z = 26): electronic configuration?","pause_after_s":0.3},{"id":"s3l3","visual":"Checklist row 'Step 1: the first 18 electrons = [Ar]' turns bright on cue 'الأولى'; the '[Ar]' chip drops into the ladder on cue 'argon' (#1); YK.tag '18' on the chip (formula '18').","tts_text":"الخطوة الأولى: أول eighteen electrons هما الـ argon، فنكتب argon بين قوسين.","screen_text":"Step 1: the first 18 electrons = [Ar]","pause_after_s":0.3},{"id":"s3l4","visual":"Row 'Step 2' bright; formula '26 - 18 = 8' builds term by term on cues 'ستة', 'تمنتاشر', 'تمانية'; eight cyan dots appear in a waiting cloud above the ladder on cue 'تمانية'.","tts_text":"يفضل twenty-six minus eighteen equals eight، يعني eight electrons لسه.","screen_text":"Step 2: 26 − 18 = 8 more electrons","pause_after_s":0.3},{"id":"s3l5","visual":"Row 'Step 3' bright; two dots fly from the cloud into the 4s tile on cue 'باتنين' (YK.flyer); formula '4s^2' appears next to the tile only once it is full; cloud now shows 6 dots.","tts_text":"نمشي على الترتيب: الـ four s الأول، وبتاخد two electrons وتتمِلي.","screen_text":"Step 3: 4s first → 4s²","pause_after_s":0.3},{"id":"s3l6","visual":"Row 'Step 4' bright; the six dots fly into the 3d tile on cue 'بيروحوا' (one after another, no counter during the flight; only the final '3d^6' label on cue 'مكان'); YK.tag 'room for 10' (formula '10') under the tile on cue 'لعشرة'.","tts_text":"والـ six الباقيين بيروحوا الـ three d، اللي بتشيل لحد ten كمان.","screen_text":"Step 4: the other 6 → 3d⁶ (3d holds up to 10)","pause_after_s":0.3},{"id":"s3l7","visual":"Result: YK.answerSlot({text:'_{26}Fe: [Ar] 4s^2 3d^6'}) + YK.rightMark on cue 'النتيجة'; the three parts pulse gold on cues 'argon' (#0), 'four', 'three' (book table p.8, book order 4s then 3d). YK.tag 'book p.8'.","tts_text":"النتيجة: الـ iron هو argon، four s two، three d six، بالترتيب ده.","screen_text":"Iron ₂₆Fe: [Ar] 4s² 3d⁶ (book p.8)","pause_after_s":0.3},{"id":"s3l8","visual":"Formula '2 + 6 = 8' under the result, the '8' links back to Step 2's '8' with a gold arc path on cue 'تمانية'; YK.rightMark on cue 'مظبوط'.","tts_text":"ونتأكد: two plus six equals eight، مظبوط.","screen_text":"Check: 2 + 6 = 8 ✓","pause_after_s":0.6},{"id":"s3l9","visual":"Picture change: Fe result shrinks to the top of the text panel as a model; YK.elementCard({sym:'Ga', Z:31, nameEn:'Gallium', config:''}) slides in on cue 'gallium'; formula '_{31}Ga' with '31' gold on cue 'واحد'.","tts_text":"دورك: الـ gallium، الـ atomic number بتاعه thirty-one كمان.","screen_text":"Your turn: Gallium ₃₁Ga, atomic number 31","pause_after_s":0.3},{"id":"s3l10","visual":"The 4-step checklist (from s3l2) re-lights on cue 'الأربعة'; an empty ladder ('[Ar]' slot, 4s, 3d, 4p tiles, all unlabelled counts) appears.","tts_text":"اكتب الـ electronic configuration بتاعه بنفس الخطوات الأربعة.","screen_text":"Write its electronic configuration with the same 4 steps","pause_after_s":0.3},{"id":"s3l11","visual":"YK.predictCard({kind:'QUICK CHECK', q:'_{31}Ga: [Ar] 4s? 3d? 4p?', at:YK.cue('s3l11'), think:YK.cueEnd('s3l11'), end:YK.cue('s3l12')}) + YK.checkPause ring through the whole pause; during the silence ONLY the question shows (no dots move, no answer).","tts_text":"وقّف الفيديو وجرّب: four s كام، three d كام، four p كام؟","screen_text":"₃₁Ga: [Ar] 4s? 3d? 4p?","pause_after_s":4},{"id":"s3l12","visual":"Answer step 1–2: '[Ar]' chip drops in on cue 'argon'; formula '31 - 18 = 13' builds on cues 'تلاتاشر', 'واحد', 'تمنتاشر'; 13 dots appear in the waiting cloud.","tts_text":"الحل: thirty-one minus eighteen equals thirteen، دول اللي بيتوزّعوا بعد الـ argon كلهم.","screen_text":"31 − 18 = 13 after [Ar]","pause_after_s":0.3},{"id":"s3l13","visual":"Two dots into 4s on cue 'اتنين', ten dots into 3d on cue 'عشرة' (labels '4s^2' and '3d^10' only when each tile is full); formula '2 + 10 = 12'.","tts_text":"الـ four s تاخد two، والـ three d تاخد ten لحد ما تتمِلي.","screen_text":"4s² + 3d¹⁰: 2 + 10 = 12","pause_after_s":0.3},{"id":"s3l14","visual":"The last dot flies into the 4p tile on cue 'بيروح'; formula '13 - 12 = 1' and label '4p^1'; the YK.flow edge 3d→4p lights gold on cue 'الدور'.","tts_text":"والـ one اللي فاضل بيروح الـ four p، عشان هو اللي عليه الدور.","screen_text":"13 − 12 = 1 → 4p¹","pause_after_s":0.3},{"id":"s3l15","visual":"YK.answerSlot({text:'_{31}Ga: [Ar] 4s^2 3d^10 4p^1'}) + YK.rightMark; parts pulse on cues 'four' (#0), 'three', 'four' (#1).","tts_text":"الـ gallium هو argon، four s two، three d ten، four p one بالترتيب.","screen_text":"Gallium ₃₁Ga: [Ar] 4s² 3d¹⁰ 4p¹ ✓","pause_after_s":0.3},{"id":"s3l16","visual":"Answer reason: the ladder edges 4s→3d→4p pulse gold in order on cues 'three' and 'four'; YK.bracket around the full 3d tile on cue 'قبل' (3d complete before the 4p dot arrives).","tts_text":"والسبب هو الترتيب: الـ three d بتتمِلي قبل ما الـ four p تاخد حاجة.","screen_text":"Reason: the order of filling, 4s then 3d then 4p","pause_after_s":0.8},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card, no roadmap); the example stage fades out.","tts_text":"طب الترتيب ده هتستخدمه فين في الباب الأول؟","screen_text":"Where Chapter 1 uses this","pause_after_s":0.8},{"id":"s4l2","visual":"YK.dBlockZoom(ctx, 96, 140, 1728, {maxH:820, p:YK.prog(t, cue 'transition', +1.2), names:1}) + YK.tag '1st' over the strip, zooms into the strip Sc → Zn; tiles Sc and Zn highlight on cues 'scandium' and 'zinc'; YK.tag 'after Ca [Ar] 4s^2: (3d) filled successively (book p.4)'.","tts_text":"أول transition series: من الـ scandium لحد الـ zinc، الـ three d بيتمِلي بالتدريج.","screen_text":"First transition series: 3d is filled successively, Sc → Zn","pause_after_s":0.3},{"id":"s4l3","visual":"Same strip: tiles Cr and Cu glow gold (highlight:['Cr','Cu']) on cues 'chromium' and 'copper'; YK.chip kind 'concept' 'Abnormal electronic configuration of chromium and copper' (map title) under the strip. No configurations drawn for them here (taught in the chapter).","tts_text":"الـ chromium والـ copper الـ electronic configuration بتاعهم abnormal، وهتشوفه في الباب.","screen_text":"Chromium and copper: abnormal electronic configuration","pause_after_s":0.3},{"id":"s4l4","visual":"YK.chip kind 'concept' 'Ions: 4s electrons are lost first' (map title, written only); Fe tiles from s3 ('[Ar]', 4s 2 dots, 3d 6 dots) with the 4s dots flying out on cue 'بيخسر' (same drawing as s2l23).","tts_text":"ولما الذرات دي تِخسر electrons، هتفتكر إن الـ four s بيخسر الأول.","screen_text":"These atoms losing electrons: 4s first","pause_after_s":0.5},{"id":"s4l5","visual":"Recap (≤ 20 s with s4l6–s4l7): YK.takeaway({title:'Aufbau principle (order of filling)', line:'Fill in order: 4s first, then 3d.', formula:'1s 2s 2p 3s 3p 4s 3d 4p', pulse:[{word:'Aufbau', at:cue 'Aufbau'}, {word:'4s', at:cue 'four'}, {word:'3d', at:cue 'three'}]}) on cue 'الخلاصة'.","tts_text":"الخلاصة حسب الـ Aufbau principle: الـ four s بتتمِلي قبل الـ three d، بالترتيب.","screen_text":"Aufbau principle (order of filling)","pause_after_s":0.3},{"id":"s4l6","visual":"Takeaway card stays; a small mint line under it 'The level number alone does not set the order' fades in on cue 'level' (no strike, no ✕).","tts_text":"ورقم الـ level لوحده مش هو اللي بيحدد مين قبل مين.","screen_text":"The level number alone does not set the order","pause_after_s":0.3},{"id":"s4l7","visual":"Voiced lock-in = the takeaway line 'Fill in order: 4s first, then 3d.'; its words pulse on cues 'four' and 'three' and stay gold; card held through the line + 1.5 s tail; the takeaway formula '1s 2s 2p 3s 3p 4s 3d 4p' stays on the card; last frame = the full ladder with 4s and 3d filled (no fade to black).","tts_text":"بالترتيب: الـ four s الأول، والـ three d بعدها.","screen_text":"Fill in order: 4s first, then 3d.","pause_after_s":1.5}],"logline":"هتعرف الـ electrons بتملا الـ sublevels بأي ترتيب، وليه الـ four s قبل الـ three d، وتكتب الـ electronic configuration لذرات زي الـ iron والـ gallium.","segments":[{"id":"s1","title":"An address for every electron","concept_id":"atom.aufbau"},{"id":"s2","title":"The order of filling (Aufbau principle)","concept_id":"atom.aufbau"},{"id":"s3","title":"Writing the electronic configuration of iron","concept_id":"atom.aufbau"},{"id":"s4","title":"Where Chapter 1 uses the 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هتطلب أكل دليفري لازم تكتب رقم العمارة\nورقم الشقة\nجوه الذرة فيه جسيمات صغيرة سالبة اسمها\nelectrons بتتحرك حوالين المركز\nوالـ electron كمان ليه عنوان زي عنوانك\nبالظبط من حاجتين\nالحاجة الأولى الـ level وده زي رقم العمارة\none two three four وكده\nالحاجة التانية الـ sublevel وده زي الشقة\nجوه العمارة\nيعني four s معناها الـ s sublevel اللي في\nlevel four بالظبط\nالـ s sublevel بيشيل two electrons بالكتير\nزي شقة صغيرة\nوالـ p sublevel بيشيل six والـ d sublevel\nبيشيل ten كمان\nوبنفس الطريقة three d معناها الـ d\nsublevel اللي في level three بالظبط\nدلوقتي السؤال المهم الـ electrons بتسكن\nالـ sublevels دي بأي ترتيب\nأي عنصر ليه atomic number وده هو عدد الـ\nelectrons في الذرة\nالـ argon مثلًا الـ atomic number بتاعه\neighteen فيه eighteen electrons جواه\nالقاعدة اسمها Aufbau principle الـ\nelectrons بتملا الـ sublevels بترتيب ثابت\nكلمة Aufbau ألماني ومعناها بناء يعني بنبني\nالذرة حتة حتة\nالترتيب بيبدأ كده one s وبعدين two s\nوبعدين two p طبيعي\nوبعدين three s وبعدها three p وكده الـ\nargon اكتمل\nوبدل ما نكتب ده تاني بنختصره ونكتب argon\nبين قوسين\nالكتابة دي اسمها electronic configuration\nيعني توزيع الـ electrons على العناوين\nالرقم الصغير فوق هو عدد الـ electrons يعني\nthree p six six هناك\nطب الـ potassium عنده nineteen electrons\nيعني one زيادة عن الـ argon بالظبط\nتوقّع الـ electron ده يروح three d ولا\nfour s فكّر ثواني\nناس كتير بتقول three d عشان three أصغر من\nfour ده غلط\nالإجابة four s الـ potassium هو argon والـ\nfour s فيها one بس\nوالـ calcium عنده twenty فالتاني برضه\nبيروح الـ four s ويقفلها\nوبعد الـ calcium الـ scandium بيحط أول\nelectron في الـ three d أخيرًا\nيعني رقم الـ level لوحده مش هو اللي بيحدد\nالترتيب\nالترتيب three p وبعدين four s وبعدين three\nd وبعدين four p في الآخر\nوعشان تفتكره بسهولة امشي على الأسهم\nالمايلة دي من فوق لتحت\nوفي العادي الـ sublevel بيتمِلي وبعدين\nننقل للي عليه الدور\nوخلّي بالك الذرة ممكن كمان تِخسر electrons\nوترتيب الخروج غير ترتيب الملء\nناس بتفتكر إن اللي اتملى الأول هو آخر واحد\nيخرج ده غلط\nبين الـ four s والـ three d الـ four s هو\nاللي بيخسر الأول\nزي الـ vanadium في الكتاب أول two\nelectrons بيخرجوا من الـ four s الأول\nوالسبب إن الـ four s في الـ level الخارجي\nرقمه four أصلًا\nالـ iron الـ atomic number بتاعه\ntwenty-six خلّينا نكتب الـ electronic\nconfiguration بتاعه\nالخطوة الأولى أول eighteen electrons هما\nالـ argon فنكتب argon بين قوسين\nيفضل twenty-six minus eighteen equals\neight يعني eight electrons لسه\nنمشي على الترتيب الـ four s الأول وبتاخد\ntwo electrons وتتمِلي\nوالـ six الباقيين بيروحوا الـ three d اللي\nبتشيل لحد ten كمان\nالنتيجة الـ iron هو argon four s two three\nd six بالترتيب ده\nونتأكد two plus six equals eight مظبوط\nدورك الـ gallium الـ atomic number بتاعه\nthirty-one كمان\nاكتب الـ electronic configuration بتاعه\nبنفس الخطوات الأربعة\nوقّف الفيديو وجرّب four s كام three d كام\nfour p كام\nالحل thirty-one minus eighteen equals\nthirteen دول اللي بيتوزّعوا بعد الـ argon\nكلهم\nالـ four s تاخد two والـ three d تاخد ten\nلحد ما تتمِلي\nوالـ one اللي فاضل بيروح الـ four p عشان\nهو اللي عليه الدور\nالـ gallium هو argon four s two three d\nten four p one بالترتيب\nوالسبب هو الترتيب الـ three d بتتمِلي قبل\nما الـ four p تاخد حاجة\nطب الترتيب ده هتستخدمه فين في الباب الأول\nأول transition series من الـ scandium لحد\nالـ zinc الـ three d بيتمِلي بالتدريج\nالـ chromium والـ copper الـ electronic\nconfiguration بتاعهم abnormal وهتشوفه في\nالباب\nولما الذرات دي تِخسر electrons هتفتكر إن\nالـ four s بيخسر الأول\nالخلاصة حسب الـ Aufbau principle الـ four\ns بتتمِلي قبل الـ three d بالترتيب\nورقم الـ level لوحده مش هو اللي بيحدد مين\nقبل مين\nبالترتيب الـ four s الأول والـ three d\nبعدها","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":73,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":130.5,"kind":"pause_question","spec":{"answer":"4s: الـ potassium هو [Ar] 4s¹؛ رقم المستوى لوحده مش هو اللي بيحدد الترتيب.","prompt":"الـ electron رقم 19 في الـ potassium: يروح 3d ولا 4s؟","options":[{"id":"a","text":"4s","correct":true},{"id":"b","text":"3d، عشان 3 أصغر من 4","correct":false}],"answer_t_s":134,"concept_id":"atom.aufbau","misconception_id":"atom.aufbau.mc1"},"content_lang":"ar-EG"},{"id":"think-2","t_s":257.33,"kind":"pause_question","spec":{"answer":"[Ar] 4s² 3d¹⁰ 4p¹: بعد الـ [Ar] فيه 13 electron؛ الـ 4s ياخد 2، والـ 3d ياخد 10، والباقي 1 في الـ 4p.","prompt":"Gallium ₃₁Ga: الـ electronic configuration بتاعه إيه؟","options":[{"id":"a","text":"[Ar] 4s² 3d¹⁰ 4p¹","correct":true},{"id":"b","text":"[Ar] 3d¹⁰ 4p³","correct":false},{"id":"c","text":"[Ar] 4s² 3d¹¹","correct":false}],"answer_t_s":262.11,"concept_id":"atom.aufbau","misconception_id":"atom.aufbau.mc1"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-atom.aufbau"]},{"id":"chem-s3-en.video-walkthrough-phys.magnetic-field","kind":"walkthrough","version":5,"ord":20,"content_lang":"ar-EG","primary_concept_id":"phys.magnetic-field","concepts":[{"concept_id":"phys.magnetic-field","role":"primary"}],"title":"Magnets and magnetic fields: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-phys.magnetic-field v3 (s1 hook fridge magnet on a steel door vs aluminum soda can + MCQ; s2 KeyTerm 'magnetic field: The region around a magnet where its magnetic force acts', field-lines diagram, 'invisible… iron filings line up along these lines', TrueFalse 'A magnet attracts all metals'; s3 'Every magnet has two poles: north (N) and south (S)', rule 'Like poles repel; unlike poles attract'; s4 Classify iron nail, steel paper clip, cobalt / copper wire, aluminum foil, gold ring + MCQ S facing S → repel; s5 recap table pulled strongly iron (and steel), cobalt, nickel vs copper, aluminum, gold, silver; exam callout 'attracts to the external magnetic field / repels the external magnetic field'; next: magnetic properties of transition elements) and its en layer (feedback: 'steel, which is mostly iron', 'a magnet doesn't noticeably pull' copper/aluminum, magnets act without touching); concept phys.magnetic-field v2 + misconception phys.magnetic-field.mc1 (refuted s2l11–s2l15: myth ✕, right model ✓ 3 metals + steel, aluminum/copper not noticeably pulled, hook answered); book Ch.1 p.13–14 '4-The Magnetic properties' (paramagnetic: attracts to the external magnetic field; diamagnetic: repels the external magnetic field) and p.? cobalt 'similar to iron… can be magnetized'. Dependent named in s4 (in-book): te.magnetic-properties (map title 'Paramagnetic and diamagnetic substances'); s4 says only that one kind attracts and the other repels the magnetic field and that which/why is the chapter's (no mapping, no unpaired electrons, no magnetic moment). atom.electron-spin-pauli and chem.mixture-separation (dependents, not in book) are not named. Terms: s1 new terms = magnet, attract, metal (3) (+ aluminum as the can's material, said in Arabic «حديد» for the door until s2 names iron). s2 = magnetic field, poles (north, south), like/unlike poles, repel, iron/cobalt/nickel, steel, copper; s3 = gold (object in the self-check). s4 names chapter words only (paramagnetic, diamagnetic). 'external magnetic field' (book) is shortened to 'the magnetic field' on screen and in speech: 3 Latin words in a row break the line rule; the meaning (a magnet's field acting on a substance from outside) is shown in s2l9–s2l10. Spelling 'aluminum' (edition rule). N/S letters only on the kit's magnet drawing; speech says north/south. Absolutes: 'pulled strongly' / 'not noticeably pulled' everywhere (never 'not attracted at all'); 'Every magnet has 2 poles' is the lesson's own sentence; 'nothing happens' for the can is the lesson's hook wording. Worked example: steel paper clip vs copper wire (lesson s4 classify items) in 3 steps; self-check NEW case: gold ring vs a piece of nickel (gold not used before; nickel as an object new), pause 4.0 s, answer + reason. Predicts: s2l7 S facing S (~1:50) and s3l8 (~3:00). Estimate: 39 lines, ~432 narration words at ~2.4 w/s + 26 s pauses = ~205 s (3.4 min); recap s4l4–s4l5 ~10 s. Visuals: YK.partCard, YK.termCard, YK.predictCard, YK.mythLine + YK.wrongMark/rightMark, YK.answerSlot, YK.arrow, YK.tag, YK.fpara, YK.panel, YK.chip, YK.takeaway, YK.checkPause (engine); YK.magnet (bar, field lines), YK.sphere (poc-science matter.js/chem.js), YK.icon('lamp'/'cable') (lab.js); fridge door, can, clip, ring, filings = page-local ctx paths (filings seeded with YK.rng). YK.magneticSample is NOT used (it draws paramagnetic/diamagnetic labels: chapter content). not-in-source: magnets pull without touching (lesson feedback 'without touching' for magnets on each other; extended to the clip); metal card 'shiny, conducts heat and electricity' (same as the oxides walkthrough, prerequisite chem.metal-properties); soda cans are made of aluminum (lesson hook says aluminum soda can); a fridge door contains iron (lesson: steel door, steel mostly iron).","title":"Magnets and magnetic fields: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor on the stage (x 790–1824): a tall grey fridge door (page-local YK.roundRect with a steel gradient, x 1000–1400, y 180–1000) and a small fridge magnet drawn as YK.magnet(ctx, 1200, 520, {type:'bar', size:180, field:0}) that slides in from the right and snaps onto the door with a small bump (YK.ease.outBack) on cue 'بيلزق'. Text panel: YK.fpara 'On the fridge door: it sticks' (48).","tts_text":"أكيد شفت المغناطيس الصغير اللي بيلزق على باب التلاجة.","screen_text":"On the fridge door: it sticks","pause_after_s":0.4},{"id":"s1l3","visual":"YK.termCard({term:'magnet', def:'an object that pulls some things toward it, even without touching', align:'left'}) on cue 'magnet'. Stage: the magnet leaves the door and hovers 120 px away; a small paper clip (page-local ctx path, C.steel) jumps across the gap to it on cue 'تلمسها' (gap visible: no touching before the jump).","tts_text":"الحاجة دي اسمها magnet، وبتشِدّ حاجات معينة ناحيتها من غير ما تلمسها.","screen_text":"magnet: an object that pulls some things toward it, even without touching","pause_after_s":0.4},{"id":"s1l4","visual":"YK.termCard({term:'attract', def:'pull toward itself', align:'left'}) on cue 'attract'; stage: a gold YK.arrow from the clip to the magnet (pointing at the magnet) draws on cue 'يشد'; YK.tag 'attract' over the arrow on cue 'attract'.","tts_text":"لما الـ magnet يشِدّ حاجة ناحيته، بنقول إنه بيعمل attract ليها.","screen_text":"attract: pull toward itself","pause_after_s":0.4},{"id":"s1l5","visual":"Back to the door: the magnet is pulled onto the door with a thick gold attract arrow (YK.arrow width 10) on cue 'بيشده'; the door gets a short shake (2 px, 0.3 s). Text panel: YK.fpara 'Fridge door: the magnet pulls it strongly' (44).","tts_text":"باب التلاجة جواه حديد، فالـ magnet بيشِدّه جامد.","screen_text":"Fridge door: the magnet pulls it strongly","pause_after_s":0.4},{"id":"s1l6","visual":"YK.termCard({term:'metal', def:'shiny, conducts heat and electricity', align:'left'}) on cue 'metal' (same card as the oxides walkthrough); stage: a shine sweep across the door on cue 'لامعة', a small circuit with a lamp YK.icon('lamp') lighting through a bar of the door metal on cue 'الكهربا'.","tts_text":"والحديد ده metal، يعني مادة لامعة وبتوصّل الكهربا والحرارة.","screen_text":"metal: shiny, conducts heat and electricity","pause_after_s":0.4},{"id":"s1l7","visual":"Picture change: a soda can (page-local ctx cylinder, light grey, no brand, no text) slides in beside the door on cue 'الكانز'; YK.tag 'aluminum' under it on cue 'aluminum'; a mint YK.tag 'metal' joins on cue 'metal'.","tts_text":"طب علبة الكانز دي معمولة من aluminum، وهو metal برضه.","screen_text":"An aluminum can: also a metal","pause_after_s":0.4},{"id":"s1l8","visual":"The magnet slides to 60 px from the can on cue 'قرّب'; the can does not move (no arrow, a dashed empty arrow outline only); a big gold '?' path above them on cue 'ليه'. Text panel: YK.fpara 'Magnet near the can: nothing happens. Why?' (48).","tts_text":"قرّب الـ magnet من العلبة، مش هيحصل حاجة. ليه بقى؟","screen_text":"Magnet near the can: nothing happens. Why?","pause_after_s":1},{"id":"s2l2","visual":"Stage: a big bar magnet YK.magnet(ctx, 1300, 580, {type:'bar', size:560, field:YK.prog(t, YK.cueX('s2l2','magnetic'), YK.cueX('s2l2','magnetic')+1.2), t}) — the dashed cyan field lines grow out from the poles on cue 'magnetic' and flow slowly; YK.termCard({term:'magnetic field', def:'the region around a magnet where its magnetic force acts', align:'left'}) on cue 'magnetic' (lesson KeyTerm wording).","tts_text":"حوالين الـ magnet فيه منطقة اسمها magnetic field، فيها قوته بتشتغل.","screen_text":"magnetic field: the region around a magnet where its magnetic force acts","pause_after_s":0.4},{"id":"s2l3","visual":"The field lines fade to 15% on cue 'بيتشاف' (invisible); ~300 short dark-grey filing strokes (seeded YK.rng positions) drop around the magnet and rotate to lie along the field-line tangents on cue 'بتترص', tracing the same curves (the lines come back to 60% under them).","tts_text":"الـ field ده مش بيتشاف، إنما الـ iron filings بتترص على خطوطه.","screen_text":"Invisible field: iron filings line up along its lines","pause_after_s":0.4},{"id":"s2l4","visual":"Filings fade; the magnet's ends glow on their cues: the N end (C.coral, kit label 'N') on cue 'north', the S end (C.atomN blue, kit label 'S') on cue 'south'; YK.tag 'north pole' / 'south pole' under each end on the same cues; YK.tag '2 poles' on cue 'poles'.","tts_text":"وأي magnet ليه طرفين اسمهم poles: الـ north والـ south كده.","screen_text":"Every magnet has 2 poles: north and south","pause_after_s":0.4},{"id":"s2l5","visual":"Picture change: two YK.magnet bars (size 360, field 0) end to end, N facing N, slide toward each other from cue 'north' (#0) and spring apart on cue 'repel' with two coral push arrows outward (YK.arrow); YK.tag 'repel' between them. Text panel: YK.fpara 'like poles (same kind): repel (push apart)' (44).","tts_text":"الـ like poles يعني نفس النوع، زي north قصاد north، بيعملوا repel وبيبعدوا.","screen_text":"like poles (same kind): repel (push apart)","pause_after_s":0.4},{"id":"s2l6","visual":"Second row under the first: two bars, N facing S, slide together and click on cue 'attract' with gold arrows inward; YK.tag 'attract'. Text panel adds YK.fpara 'unlike poles: attract' (44) under the first rule.","tts_text":"والـ unlike poles، يعني north قصاد south، بيعملوا attract لبعض.","screen_text":"unlike poles: attract","pause_after_s":0.4},{"id":"s2l7","visual":"YK.predictCard(ctx, t, {kind:'PREDICT', q:'South faces south. Attract or repel?', at:YK.cue('s2l7'), think:YK.cueEnd('s2l7'), end:YK.cue('s2l8')}); stage: a new pair of bars, S facing S, frozen 200 px apart (no arrows) during the think ring.","tts_text":"توقّع: لو الـ south قصاد الـ south، يحصل attract ولا repel؟ فكّر.","screen_text":"Predict: south faces south. Attract or repel?","pause_after_s":3},{"id":"s2l8","visual":"Answer: the S–S pair pushes apart on cue 'repel' (coral arrows outward) while still 200 px apart (gap kept visible); YK.answerSlot({text:'Like poles -> repel'}) + YK.rightMark on cue 'like'.","tts_text":"بيعملوا repel، لأنهم like poles، حتى من غير ما يلمسوا بعض.","screen_text":"Like poles → repel ✓ (no touching needed)","pause_after_s":0.6},{"id":"s2l9","visual":"Picture change: one bar magnet with its field (field 1) at the right of the stage; a small grey block (no label) at the left moves toward it along a gold arrow on cue 'اتشدت'; YK.tag 'attracts' on cue 'attract'; the field lines that touch the block glow on cue 'magnetic'.","tts_text":"لو المادة اتشدّت ناحية الـ magnet، بنقول بتعمل attract مع الـ magnetic field بتاعه.","screen_text":"Pulled toward the magnet: it attracts to the magnetic field","pause_after_s":0.4},{"id":"s2l10","visual":"Same set: a second grey block (no label) drifts away from the magnet along a coral arrow on cue 'اتبعدت'; YK.tag 'repels' on cue 'repel'. Both outcomes now side by side (attracts / repels), the words matching the chapter's phrasing.","tts_text":"لو المادة اتبعدت عن الـ magnet، يبقى بتعمل repel مع الـ magnetic field بتاعه.","screen_text":"Pushed away: it repels the magnetic field","pause_after_s":0.4},{"id":"s2l11","visual":"Myth beat (phys.magnetic-field.mc1): YK.mythLine(ctx, t, {at:YK.cue('s2l11'), wrongAt:YK.cueX('s2l11','غلط'), until:YK.cueEnd('s2l12')+1.5, text:'A magnet attracts all metals', x:96, y:300, size:44}) in coral; on the stage a small coral picture (60% size): a magnet with coral arrows pulling a row of six metal chunks; YK.wrongMark on both on cue 'غلط', ✕ held for their whole visible time; nothing struck through.","tts_text":"ناس كتير فاكرة إن الـ magnet بيعمل attract لكل الـ metals. ده غلط.","screen_text":"A magnet attracts all metals","pause_after_s":0.4},{"id":"s2l12","visual":"Right model, bigger and held longer than the myth: magnet (size 420, field on) at (1300, 420); three metal chunks YK.sphere(ctx, x, 820, 70, C.steel) at x 1000 / 1300 / 1600 jump to it on cues 'iron', 'cobalt', 'nickel', each with a gold attract arrow and a YK.tag label on its cue; YK.rightMark + YK.tag '3' on cue 'three'.","tts_text":"الـ magnet بيشِدّ بقوة three metals: الـ iron والـ cobalt والـ nickel كمان.","screen_text":"Pulled strongly: 3 metals, iron, cobalt, nickel ✓","pause_after_s":0.4},{"id":"s2l13","visual":"Small callback inset: the fridge door with its magnet (s1l5 drawing) on cue 'التلاجة'; YK.tag 'steel' on the door on cue 'steel' and a small 'iron' chunk icon inside the door outline on cue 'iron'.","tts_text":"والـ steel أغلبه iron، عشان كده باب التلاجة اتشدّ.","screen_text":"steel: mostly iron, so it is pulled too","pause_after_s":0.4},{"id":"s2l14","visual":"Two more chunks on the stage: the soda can (aluminum, light grey) on cue 'aluminum' and a copper wire coil (C.atomCu, YK.icon('cable') as in the concept's short) on cue 'copper'; the magnet sweeps past them and they stay put (4 px wobble at most, no arrows); YK.tag 'not noticeably pulled' (textDim) under them on cue 'واضح'. Never 'not at all'.","tts_text":"أما الـ aluminum والـ copper، metals برضه، إنما مش بيتشدّوا بشكل واضح.","screen_text":"Not noticeably pulled: aluminum, copper (metals too)","pause_after_s":0.4},{"id":"s2l15","visual":"The myth picture is gone; a two-column board (YK.panel) sums up: left 'Pulled strongly' (iron, cobalt, nickel, steel), right 'Not noticeably pulled' (aluminum, copper), both under one header 'metal' on cue 'metal'; the can from s1 pulses on cue 'العلبة' (answers the hook). No strike, no ✕ on this negated sentence; YK.rightMark on cue 'كفاية'.","tts_text":"يعني إنها تبقى metal مش كفاية، وعشان كده العلبة مش بتتشِدّ.","screen_text":"Being a metal is not enough ✓","pause_after_s":1},{"id":"s3l2","visual":"Stage: a paper clip (page-local ctx path, C.steel) and a copper wire coil (YK.icon('cable'), C.atomCu) on a table line, magnet hovering above (field 0.5); YK.tag 'steel' / 'copper' on cues 'steel' / 'copper'. Text panel: a 3-step checklist (YK.fpara rows 'Step 1' … 'Step 3', dim) under the question (44).","tts_text":"عندنا مشبك ورق steel، وسِلك copper، مين فيهم هيتشِدّ بقوة؟","screen_text":"A steel paper clip and a copper wire: which is pulled strongly?","pause_after_s":0.3},{"id":"s3l3","visual":"Row 'Step 1' bright on cue 'الأولى'; each object gets a material badge (YK.chip) on cues 'steel' and 'copper'.","tts_text":"الخطوة الأولى: الـ steel في المشبك، والـ copper في السِلك.","screen_text":"Step 1: what is it made of? clip: steel · wire: copper","pause_after_s":0.3},{"id":"s3l4","visual":"Row 'Step 2' bright; the 'list of 3' card (iron · cobalt · nickel, from s2l12) appears small at the top of the stage; the steel badge links to 'iron' with a mint path + ✓ on cue 'iron'; the copper badge gets a grey 'not on the list' tag on cue 'three' (no ✕: copper is not a wrong idea).","tts_text":"الخطوة التانية: الـ steel أغلبه iron، أما الـ copper فمش من الـ three دول.","screen_text":"Step 2: on the list of 3? steel (mostly iron): yes · copper: no","pause_after_s":0.3},{"id":"s3l5","visual":"Row 'Step 3' bright; the magnet lowers: the clip jumps up to it with a gold attract arrow on cue 'بقوة'; the wire stays on the table (4 px wobble, no arrow) on cue 'واضح'.","tts_text":"الخطوة التالتة: المشبك هيتشِدّ بقوة، والسِلك مش هيتشِدّ بشكل واضح.","screen_text":"Step 3: clip → pulled strongly · wire → not noticeably pulled","pause_after_s":0.3},{"id":"s3l6","visual":"YK.answerSlot({text:'Steel clip: pulled · copper wire: not noticeably'}) + YK.rightMark on cue 'النتيجة'; clip held on the magnet, wire on the table.","tts_text":"النتيجة: الـ magnet يشِدّ المشبك الـ steel، ويسيب سِلك الـ copper تقريبًا.","screen_text":"Result: the magnet pulls the steel clip ✓ · copper wire: not noticeably","pause_after_s":0.6},{"id":"s3l7","visual":"Picture change: the clip/wire result shrinks to the top of the text panel as the model; stage: a gold ring (page-local ctx torus, C.gold — the real colour of gold) on cue 'gold' and a small nickel chunk (YK.sphere, C.steel lighter) on cue 'nickel', magnet hovering above them, nothing moves.","tts_text":"دورك: خاتم من الـ gold، وحتة nickel، مين فيهم هيتشِدّ بقوة؟","screen_text":"Your turn: a gold ring and a piece of nickel. Which is pulled strongly?","pause_after_s":0.3},{"id":"s3l8","visual":"YK.predictCard(ctx, t, {kind:'QUICK CHECK', q:'Gold ring or nickel: which is pulled strongly?', at:YK.cue('s3l8'), think:YK.cueEnd('s3l8'), end:YK.cue('s3l9')}) + YK.checkPause ring through the whole pause; the 3-step checklist re-lights; during the silence ONLY the question shows (nothing moves, no answer).","tts_text":"وقّف الفيديو، وجرّب بنفس التلات خطوات قبل ما نكمّل.","screen_text":"Pause: use the same 3 steps","pause_after_s":4},{"id":"s3l9","visual":"The nickel chunk jumps to the magnet with a gold attract arrow on cue 'فهيتشد'; the 'list of 3' card flashes 'nickel' on cue 'three'; YK.rightMark.","tts_text":"الـ nickel من الـ three دول، فهيتشِدّ بقوة ناحية الـ magnet بوضوح.","screen_text":"nickel: one of the 3 → pulled strongly ✓","pause_after_s":0.3},{"id":"s3l10","visual":"The ring stays on the table (4 px wobble, no arrow) on cue 'فمش'; YK.tag 'metal' on the ring on cue 'metal'; YK.rightMark next to the answer line (the answer is right, the ring is not 'wrong': no ✕).","tts_text":"والـ gold metal، إنما مش من الـ three دول، فمش هيتشِدّ بشكل واضح.","screen_text":"gold: a metal, but not one of the 3 → not noticeably pulled ✓","pause_after_s":0.3},{"id":"s3l11","visual":"The two-column board of s2l15 returns small with 'nickel' added to the left column and 'gold' to the right column on cue 'metal'; header 'metal' over both columns pulses on cue 'كفاية'.","tts_text":"والسبب: إن المادة تبقى metal مش كفاية عشان الـ magnet يشِدّها.","screen_text":"Reason: being a metal is not enough","pause_after_s":0.8},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الباب الأول؟","screen_text":"Where Chapter 1 uses this","pause_after_s":0.8},{"id":"s4l2","visual":"YK.chip kind 'concept' 'Paramagnetic and diamagnetic substances' (map title) slides into the text panel on cue 'paramagnetic'; stage: the two 'substance' blocks of s2l9–s2l10 return beside the magnet, unlabelled (which is which is the chapter's).","tts_text":"في الباب الأول هتدرس substances اسمها paramagnetic، وتانية اسمها diamagnetic كمان.","screen_text":"Chapter 1: paramagnetic and diamagnetic substances","pause_after_s":0.3},{"id":"s4l3","visual":"The left block moves toward the magnet (gold arrow) on cue 'attract', the right block moves away (coral arrow) on cue 'repel'; a small gold '?' tag 'Why? In the chapter' on cue 'والسبب'. No electrons, no reasons drawn here.","tts_text":"نوع بيعمل attract ناحية الـ magnetic field، والتاني بيعمل repel، والسبب في الباب.","screen_text":"One kind: attract · the other: repel (the magnetic field). Why? In the chapter.","pause_after_s":0.5},{"id":"s4l4","visual":"Recap (≤ 20 s with s4l5): YK.takeaway({title:'Magnets and magnetic fields', line:'A magnet does not attract all metals.', formula:'like poles repel · unlike poles attract', pulse:[{word:'Magnets', at:cue 'magnet'}]}) on cue 'الخلاصة'; behind it the bar magnet with its field lines (dimmed 35%).","tts_text":"الخلاصة: الـ magnet حواليه magnetic field، والـ like poles بيعملوا repel لبعض.","screen_text":"Magnets and magnetic fields · like poles repel","pause_after_s":0.3},{"id":"s4l5","visual":"Voiced lock-in = the takeaway line 'A magnet does not attract all metals.' (negated: no strike, no ✕); 'not' pulses gold on cue 'مش'; card held through the line + 1.5 s tail; last frame = the board 'Pulled strongly / Not noticeably pulled' under the card (no fade to black).","tts_text":"الـ magnet مش بيعمل attract لكل الـ metals، خلّي بالك.","screen_text":"A magnet does not attract all metals.","pause_after_s":1.5}],"logline":"هتعرف يعني إيه magnetic field، وإمتى الـ poles بتعمل attract أو repel، وليه الـ magnet مش بيشد أي metal.","segments":[{"id":"s1","title":"A fridge magnet and a can","concept_id":"phys.magnetic-field"},{"id":"s2","title":"Magnetic fields, poles and the three metals","concept_id":"phys.magnetic-field"},{"id":"s3","title":"Which one does the magnet pull?","concept_id":"phys.magnetic-field"},{"id":"s4","title":"Where Chapter 1 uses 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شفت المغناطيس الصغير اللي بيلزق على\nباب التلاجة\nالحاجة دي اسمها magnet وبتشِد حاجات معينة\nناحيتها من غير ما تلمسها\nلما الـ magnet يشِد حاجة ناحيته بنقول إنه\nبيعمل attract ليها\nباب التلاجة جواه حديد فالـ magnet بيشِدّه\nجامد\nوالحديد ده metal يعني مادة لامعة وبتوصّل\nالكهربا والحرارة\nطب علبة الكانز دي معمولة من aluminum وهو\nmetal برضه\nقرّب الـ magnet من العلبة مش هيحصل حاجة\nليه بقى\nحوالين الـ magnet فيه منطقة اسمها magnetic\nfield فيها قوته بتشتغل\nالـ field ده مش بيتشاف إنما الـ iron\nfilings بتترص على خطوطه\nوأي magnet ليه طرفين اسمهم poles الـ north\nوالـ south كده\nالـ like poles يعني نفس النوع زي north\nقصاد north بيعملوا repel وبيبعدوا\nوالـ unlike poles يعني north قصاد south\nبيعملوا attract لبعض\nتوقّع لو الـ south قصاد الـ south يحصل\nattract ولا repel فكّر\nبيعملوا repel لأنهم like poles حتى من غير\nما يلمسوا بعض\nلو المادة اتشدّت ناحية الـ magnet بنقول\nبتعمل attract مع الـ magnetic field بتاعه\nلو المادة اتبعدت عن الـ magnet يبقى بتعمل\nrepel مع الـ magnetic field بتاعه\nناس كتير فاكرة إن الـ magnet بيعمل attract\nلكل الـ metals ده غلط\nالـ magnet بيشِد بقوة three metals الـ\niron والـ cobalt والـ nickel كمان\nوالـ steel أغلبه iron عشان كده باب التلاجة\nاتشد\nأما الـ aluminum والـ copper metals برضه\nإنما مش بيتشدّوا بشكل واضح\nيعني إنها تبقى metal مش كفاية وعشان كده\nالعلبة مش بتتشِد\nعندنا مشبك ورق steel وسِلك copper مين فيهم\nهيتشِد بقوة\nالخطوة الأولى الـ steel في المشبك والـ\ncopper في السِلك\nالخطوة التانية الـ steel أغلبه iron أما\nالـ copper فمش من الـ three دول\nالخطوة التالتة المشبك هيتشِد بقوة والسِلك\nمش هيتشِد بشكل واضح\nالنتيجة الـ magnet يشِد المشبك الـ steel\nويسيب سِلك الـ copper تقريبًا\nدورك خاتم من الـ gold وحتة nickel مين فيهم\nهيتشِد بقوة\nوقّف الفيديو وجرّب بنفس التلات خطوات قبل\nما نكمّل\nالـ nickel من الـ three دول فهيتشِد بقوة\nناحية الـ magnet بوضوح\nوالـ gold metal إنما مش من الـ three دول\nفمش هيتشِد بشكل واضح\nوالسبب إن المادة تبقى metal مش كفاية عشان\nالـ magnet يشِدّها\nطب الكلام ده هيفيدك فين في الباب الأول\nفي الباب الأول هتدرس substances اسمها\nparamagnetic وتانية اسمها diamagnetic كمان\nنوع بيعمل attract ناحية الـ magnetic field\nوالتاني بيعمل repel والسبب في الباب\nالخلاصة الـ magnet حواليه magnetic field\nوالـ like poles بيعملوا repel لبعض\nالـ magnet مش بيعمل attract لكل الـ metals\nخلّي بالك","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":74,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":67.16,"kind":"pause_question","spec":{"answer":"repel: دول like poles، فبيزقّوا بعض حتى من غير ما يلمسوا.","prompt":"الـ south قصاد الـ south: attract ولا repel؟","options":[{"id":"a","text":"repel","correct":true},{"id":"b","text":"attract","correct":false}],"answer_t_s":71,"concept_id":"phys.magnetic-field"},"content_lang":"ar-EG"},{"id":"think-2","t_s":160.89,"kind":"pause_question","spec":{"answer":"الـ nickel: من التلاتة (iron, cobalt, nickel). الـ gold metal برضه، لكن مش بيتشد بشكل ملحوظ.","prompt":"خاتم gold وحتة nickel: مين فيهم بيتشد بقوة ناحية الـ magnet؟","options":[{"id":"a","text":"الـ nickel","correct":true},{"id":"b","text":"الـ gold","correct":false},{"id":"c","text":"الاتنين، عشان الاتنين metals","correct":false}],"answer_t_s":165.44,"concept_id":"phys.magnetic-field","misconception_id":"phys.magnetic-field.mc1"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-phys.magnetic-field"]},{"id":"chem-s3-en.video-walkthrough-atom.electron-spin-pauli","kind":"walkthrough","version":7,"ord":22,"content_lang":"ar-EG","primary_concept_id":"atom.electron-spin-pauli","concepts":[{"concept_id":"atom.electron-spin-pauli","role":"primary"}],"title":"Electron spin and the Pauli principle: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-atom.electron-spin-pauli v1 (s1 hook 'two tiny magnets in one box' + distractors 'add up' / 'one stops spinning'; s2 Remember orbital wording + spin KeyTerm + trap '↓ = negative or missing electron'; s3 Pauli KeyTerm 'One orbital holds two electrons at most, and they must have opposite spins'; s4 interact empty → ↑ → ↑↓ → third electron to another orbital; s5 checks; s6 recap, 'next: magnetic properties of transition elements, Chapter 1'); ar-EG and en layers; concept atom.electron-spin-pauli v2 (no recorded misconceptions: s2 refutes the lesson's trap (↓, s2l8–s2l9) and both hook distractors (add up s2l15, stops spinning s2l16); s1l10 refutes the prerequisite misconception atom.orbitals.mc1 'orbital = circular path'); prereq summaries atom.orbitals, phys.magnetic-field (magnets attract some materials like iron; avoided 'all metals'); book Ch.1 '4-The Magnetic properties' pp.13–14 (unpaired electrons (↑) form a magnetic field due to spinning; paired ↑↓ opposite spins, moment zero) used only to name the dependent. Dependents named in s4 (map title_en exactly): atom.hund-rule 'Hund's rule and orbital-box diagrams', atom.electron-configuration-writing 'Writing electronic configurations', and the in-book te.magnetic-properties 'Paramagnetic and diamagnetic substances' (via atom.hund-rule; the lesson's 'next' callout). s4 adds no fact: the filling order and attraction/repulsion are left to the chapter. Terms (defined at first use): s1 nucleus, electron, orbital (3; 'atom' and 'magnet' are said in Arabic only in s1, never shown in English); s2 spin, magnet, magnetic field, magnetic effect, Pauli principle, opposite spins, pair, unpaired electron; s3/s4 none new (s4 chips are dependent titles). Wording choice: the term card says 'Pauli principle' (the map title_en form, 'Electron spin and the Pauli principle') because 'Pauli exclusion principle' is three Latin words in a row (narration line rule); the definition is the lesson's verbatim. Pauli in orbital form only (rule chem-s3-en.fact.pauli-orbital-form). 'unpaired' never 'lone/left alone' on screen. Arrows ↑/↓ are drawn with YK.spinArrow (Cairo lacks ↑↓), ↑ cyan, ↓ pink (G5); no orbit rings (G30); bar magnets drawn page-local without pole letters (no unspoken Latin letters). The worked example fills ONE orbital (lesson interact) and never shows which orbital of a sublevel fills first (avoids atom.hund-rule.mc1). Self-check (new case): [↑↓] [↓↓] [↓] — which breaks Pauli; answer [↓↓] with reason; lone ↓ called a normal unpaired electron (callback to the ↓ trap). Predicts: s2l10 (3.0 s), s3l8 (4.0 s). not-in-source: s1l4 two bar magnets side by side pointing the same way give a stronger pull (everyday anchor); s1l5 two bar magnets side by side pointing opposite ways: their effects (nearly) cancel, the paperclip barely moves (everyday anchor, mirrors the lesson's 'two tiny magnets point opposite ways, so their magnetic effects cancel'); s2l6 'magnetic effect' glossed as the pull or push of a magnet. Estimate: 50 lines, ~555 words at ~2.4 words/s ≈ 230 s + 39.5 s pauses ≈ 270 s (≈ 4.5 min); recap s4l6–s4l8 ≈ 16 s.","title":"Electron spin and the Pauli principle: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor: YK.camera push-in (1.0 s, inOut) on the magnet on cue 'مغناطيس'; the magnet slides onto the door and stops with a small settle (YK.tween outBack) on cue 'بيلزق'. Text panel: YK.fpara 'Sticks to the fridge door' (44) at (96, 300).","tts_text":"بص على مغناطيس التلاجة: بيلزق في الباب من غير صَمغ.","screen_text":"Sticks to the fridge door","pause_after_s":0.4},{"id":"s1l3","visual":"New shot: the bar magnet on a table (page-local bar, no letters); a paperclip (page-local ctx path, C.steel) slides toward it on cue 'بيشدّه' and stops touching nothing, a 40 px gap kept; faint dashed cyan arcs (page-local, alpha 0.4) breathe around the magnet (G34 style). Text panel: YK.fpara 'Pulls a paperclip without touching it' (44).","tts_text":"ولو قرّبت منه مشبك ورق، بيشِدّه ناحيته من غير ما يلمسه.","screen_text":"Pulls a paperclip without touching it","pause_after_s":0.4},{"id":"s1l4","visual":"Stage: two page-local bar magnets side by side, coral halves both on top, on cue 'مغناطيسين' (numbers on screen/visual: 2); the paperclip jumps closer on cue 'بيزيد' and the dashed arcs grow (alpha 0.4 → 0.7). YK.rightMark small next to 'stronger pull'. Text panel: YK.fpara 'Side by side, same way: stronger pull' (44).","tts_text":"ولو حطّينا مغناطيسين جنب بعض في نفس الاتجاه، الشدّ بيزيد.","screen_text":"Side by side, same way: stronger pull","pause_after_s":0.4},{"id":"s1l5","visual":"The right magnet flips 180° (0.5 s, inOut) on cue 'عكس' (coral half now at the bottom); the dashed arcs fade to alpha 0.1 on cue 'بيلغي' and the paperclip slides back and nearly stops on 'يدوب'. Text panel: YK.fpara 'Opposite ways: their effects cancel' (44) with 'cancel' in gold (accent span). This picture returns in s2l12.","tts_text":"إنما لو عكس بعض، تأثيرهم بيلغي بعضه، والمشبك يدوب بيتحرك.","screen_text":"Opposite ways: their effects cancel","pause_after_s":0.6},{"id":"s1l6","visual":"YK.zoomThrough(ctx, t, {from: drawPaperclip, to: drawAtomCloud, p: prog from cue 'ندخل' over 1.2 s, badge: '×10^8'}) with YK.scaleBadge for 1.5 s (G25). drawAtomCloud = a page-local soft radial-gradient cloud (cyan, alpha ≤ 0.25) around an empty centre; no orbit rings (G30). Text panel empty except the segment chip (the zoom is the picture).","tts_text":"دلوقتي ندخل جوه حتة صغيرة جدًا من المادة، اسمها الذرة.","screen_text":"","pause_after_s":0.4},{"id":"s1l7","visual":"A small bright centre (YK.glowCircle, C.amber, r 30) grows in the middle of the cloud on cue 'مركز'; YK.tag 'nucleus' (40) points to it on cue 'nucleus'. Text panel: YK.termCard(ctx, 96, 420, {term: 'nucleus', align: 'left', p: from cue 'nucleus'}).","tts_text":"في نص الذرة فيه مركز صغير اسمه الـ nucleus، يعني النواة.","screen_text":"nucleus","pause_after_s":0.4},{"id":"s1l8","visual":"Three cyan electron dots (YK.dot, glow) drift through the cloud (seeded paths via YK.rng, never circles) from cue 'بتتحرك'; a small '−' badge on each on cue 'سالبة'. Text panel: YK.termCard(ctx, 96, 560, {term: 'electron', align: 'left', p: from cue 'electrons'}) + YK.tag '(−)' beside it; the nucleus card dims to 35%.","tts_text":"وحواليه بتتحرك electrons، جسيمات صغيرة جدًا، شُحنتها سالبة.","screen_text":"electron (−)","pause_after_s":0.4},{"id":"s1l9","visual":"Definition card (the lesson's own wording, step s2 'Remember'): YK.termCard(ctx, 96, 380, {term: 'orbital', def: 'the region around the nucleus where an electron is most likely found', keys: ['region', 'most likely'], align: 'left', p: from cue 'orbital'}), alone in the panel. Stage: the cloud brightens into one soft blob around the nucleus (page-local radial gradient, cyan) on cue 'المنطقة'; one electron dot flickers to a few seeded spots inside it on 'غالبًا'.","tts_text":"والـ orbital هو المنطقة حوالين الـ nucleus، اللي الـ electron غالبًا بيكون فيها.","screen_text":"orbital: the region around the nucleus where an electron is most likely found","pause_after_s":0.6},{"id":"s1l10","visual":"Prerequisite myth (atom.orbitals.mc1): YK.mythLine(ctx, t, {at: YK.cue('s1l10'), wrongAt: YK.cueX('s1l10','مش'), until: YK.cueEnd('s1l10') + 1.5, text: 'orbital: a circular path?', x: 96, y: 300, size: 48}) with ✕; on the stage a thin coral circle path (page-local) is drawn around the nucleus with a YK.wrongMark for its whole visible time, then fades on cue 'منطقة' while the cyan blob pulses; YK.answerSlot(ctx, t, {at: YK.cueX('s1l10','منطقة'), text: 'a region', x: 300, y: 520}) ✓ held 1.5 s past the line. No strike-through.","tts_text":"خلّي بالك: الـ orbital مش مسار دايري زي الكواكب، ده منطقة.","screen_text":"orbital: a circular path? ✕  a region ✓","pause_after_s":0.6},{"id":"s1l11","visual":"Match cut: the blob shrinks and squares into one empty orbital box YK.electronBoxes(ctx, 1307, 560, {boxes: 1, electrons: 0, size: 220, label: '', labelPos: 'none'}) on cue 'مربع'. Text panel: YK.fpara 'orbital → drawn as a box' (44) on cue 'orbital'.","tts_text":"وعشان نرسم الـ orbital بسهولة، بنرسمه مربع صغير زي ده.","screen_text":"orbital → drawn as a box","pause_after_s":0.4},{"id":"s1l12","visual":"Micro-recap: the three term cards collapse into three YK.chip(ctx, 96, y, label, {kind: 'concept', align: 'left'}) at y 300 / 400 / 500 on cues 'nucleus' / 'electron' / 'orbital'; stage: the empty box stays, a cyan electron dot hovers beside it.","tts_text":"يبقى كده عرفنا الـ nucleus والـ electron والـ orbital كويس.","screen_text":"nucleus · electron · orbital","pause_after_s":1},{"id":"s2l2","visual":"Analogy shot (G3, dropped next line): a toy spinning top (page-local ctx: cone + handle, two stripes that rotate with t) on cue 'نحلة'; a curved arrow (page-local arc, C.gold) circles its axis on cue 'بتلف'. Text panel: YK.fpara 'A toy top turns around itself' (44).","tts_text":"تخيّل نَحلة لعبة بتلِفّ حوالين نفسها بسرعة على الأرض.","screen_text":"A toy top turns around itself","pause_after_s":0.4},{"id":"s2l3","visual":"Real model replaces the top (match cut on the curved arrow): one electron sphere (YK.dot r 70, C.cyan, glow, a rotating highlight drawn with t) with the same gold curved arrow around it on cue 'electron'. Text panel: YK.termCard(ctx, 96, 420, {term: 'spin', align: 'left', p: from cue 'spin'}).","tts_text":"والـ electron كمان بيعمل spin، يعني بيلِفّ حوالين نفسه.","screen_text":"spin","pause_after_s":0.4},{"id":"s2l4","visual":"A small page-local bar magnet (coral / C.atomN halves, no letters, 120 px) fades in INSIDE the spinning sphere on cue 'magnet'; YK.tag 'magnet' (40) beside it. Text panel line under the spin card: YK.fpara 'spin → electron = a magnet' (44), parts lighting on cues 'spin' / 'electron' / 'magnet'.","tts_text":"والـ spin ده بيخلّي الـ electron يتصرّف زي magnet صغير، يعني مغناطيس.","screen_text":"spin → electron = a magnet","pause_after_s":0.4},{"id":"s2l5","visual":"Dashed cyan field arcs (page-local, same drawing as s1l3) grow around the sphere on cue 'magnetic'; YK.tag 'magnetic field' (40) on the arcs. Text panel: YK.termCard(ctx, 96, 560, {term: 'magnetic field', align: 'left', p: from cue 'magnetic'}); the spin card dims to 35%. Book p.13: unpaired electrons form a magnetic field due to their spinning.","tts_text":"والـ magnet ده بيعمل حواليه magnetic field، يعني منطقة بيبان فيها تأثيره.","screen_text":"magnetic field: around the magnet","pause_after_s":0.4},{"id":"s2l6","visual":"The paperclip of s1l3 (small, page-local) slides toward the sphere on cue 'والشد'; YK.tag 'magnetic effect' (40, gold outline) on cue 'magnetic'. Text panel: YK.fpara 'magnetic effect = its pull or push' (44).","tts_text":"والشدّ أو الزقّ ده اسمه الـ magnetic effect، يعني التأثير المغناطيسي.","screen_text":"magnetic effect = its pull or push","pause_after_s":0.4},{"id":"s2l7","visual":"New picture: two electron spheres side by side (x 1150 / 1450); the left spins one way, the right the other way (curved arrows opposite) on cue 'اتجاهين' (number in visual: 2). Each collapses into a spin arrow drawn with YK.spinArrow (page draws arrows; Cairo lacks ↑↓): ↑ cyan on cue 'لفوق', ↓ pink on cue 'لتحت' (G5). Text panel: YK.fpara 'Two spin directions:' + the two arrows drawn with YK.spinArrow inline.","tts_text":"والـ spin ليه اتجاهين، وبنرسمهم سهم لفوق وسهم لتحت.","screen_text":"Two spin directions: ↑ and ↓","pause_after_s":0.6},{"id":"s2l8","visual":"Lesson trap (step s2): YK.mythLine(ctx, t, {at: YK.cue('s2l8'), wrongAt: YK.cueX('s2l8','غلط'), until: YK.cueEnd('s2l9') + 1.5, text: '↓ = a different or missing electron?', x: 96, y: 300, size: 48}) coral with ✕ for its whole visible time (↓ drawn with YK.spinArrow pink); on the stage the ↓ arrow gets a YK.wrongMark small beside it, the ↑ stays plain.","tts_text":"ناس فاكرة إن السهم اللي لتحت ده electron ناقص أو مختلف، وده غلط.","screen_text":"↓ = a different or missing electron? ✕","pause_after_s":0.4},{"id":"s2l9","visual":"Fix held ≥ the myth: the ↓ arrow morphs back into an electron sphere identical to the ↑ one (same size, same cyan body, same '−' badge) on cue 'عادي', spinning the other way (curved arrow reversed) on cue 'العكسي'; YK.rightMark next to it. YK.answerSlot(ctx, t, {at: YK.cueX('s2l9','عادي'), text: 'the same electron, other spin direction', x: 300, y: 560}).","tts_text":"ده electron عادي زي التاني بالظبط، إنما بيعمل spin في الاتجاه العكسي.","screen_text":"↓: the same electron, other spin direction ✓","pause_after_s":0.6},{"id":"s2l10","visual":"YK.predictCard(ctx, t, {at: YK.cue('s2l10'), until: YK.cue('s2l11') + 0.4, think: YK.cueEnd('s2l10'), end: YK.cue('s2l11'), kind: 'PREDICT', q: 'Two electrons in one orbital. Their magnetic effects?'}) (numbers: 2 electrons, 1 orbital); stage: one empty box YK.electronBoxes(ctx, 1307, 560, {boxes: 1, electrons: 0, size: 240, labelPos: 'none'}) with two cyan dots hovering above it. Only the question shows through the think ring.","tts_text":"طب لو two electrons في one orbital، الـ magnetic effects بتاعتهم هيحصلها إيه؟","screen_text":"PREDICT: two electrons in one orbital. Their magnetic effects?","pause_after_s":3},{"id":"s2l11","visual":"Definition card, first clause (lesson step s3 KeyTerm wording; the map title's short form 'Pauli principle' is used for the term): YK.termCard(ctx, 96, 340, {term: 'Pauli principle', def: 'One orbital holds two electrons at most,', keys: ['two electrons at most'], align: 'left', p: from cue 'Pauli'}) (numbers: 1 orbital, 2 electrons). Stage: two electrons drop into the box (YK.flyer arcs) on cue 'two'.","tts_text":"الـ Pauli principle بيقول: كل orbital ياخد two electrons بالكتير.","screen_text":"Pauli principle: One orbital holds two electrons at most,","pause_after_s":0.3},{"id":"s2l12","visual":"Card completes: YK.fpara '…and they must have opposite spins' (40) under the first clause, 'opposite spins' gold on cue 'opposite'; the box fills as YK.electronBoxes(…, {electrons: ['↑↓'], fill: prog from cue 'لفوق' to cue 'لتحت'}) — ↑ cyan then ↓ pink (numbers: 1 up, 1 down).","tts_text":"ولازم يكون ليهم opposite spins، يعني واحد سهم لفوق وواحد لتحت.","screen_text":"…and they must have opposite spins (↑↓).","pause_after_s":0.6},{"id":"s2l13","visual":"Answer to the predict: a small page-local bar magnet appears on each arrow, pointing opposite ways, on cue 'magnets'; callback inset (YK.panel 1500, 220, 300, 220) replays the two flipped fridge magnets of s1l5 on 'عكس'; the field arcs around the box fade to alpha 0.1 on cue 'بتلغي'. YK.answerSlot(ctx, t, {at: YK.cueX('s2l13','بتلغي'), text: '↑↓: the magnetic effects cancel', x: 300, y: 700}). Numbers in screen/visual: 2.","tts_text":"فالـ magnets الصغيرين بيبصّوا عكس بعض، والـ magnetic effects بتلغي بعض.","screen_text":"↑↓: two magnets → the magnetic effects cancel","pause_after_s":0.6},{"id":"s2l14","visual":"YK.bracket(ctx, box.x0 - 12, box.y0 - 12, box.w + 24, box.h + 24, prog from cue 'pair') in gold around the ↑↓ box; YK.tag 'pair' (40) under it on cue 'pair'. Text panel: YK.fpara '↑↓ in one orbital: a pair' (44) (numbers: 2 electrons, 1 orbital).","tts_text":"والـ two اللي في one orbital كده بنسميهم pair، يعني جوز.","screen_text":"↑↓ in one orbital: a pair","pause_after_s":0.4},{"id":"s2l15","visual":"Lesson hook distractor: YK.mythLine(ctx, t, {at: YK.cue('s2l15'), wrongAt: YK.cueX('s2l15','غلط'), until: YK.cueEnd('s2l16') + 1.5, text: 'A stronger orbital, the effects add up?', x: 96, y: 300, size: 46}) with ✕ for its whole visible time; stage: a ghost coral version of the box with two ↑ magnets and doubled field arcs, marked YK.wrongMark, beside the real ↑↓ box.","tts_text":"ناس بتفتكر إن التأثيرين بيتجمعوا والـ orbital يبقى مغناطيس أقوى؛ غلط.","screen_text":"A stronger orbital, the effects add up? ✕","pause_after_s":0.4},{"id":"s2l16","visual":"Fix held ≥ the myths: the ghost box fades; in the real box both arrows keep a small curved-arrow spin indicator turning (opposite senses) from cue 'لسه'; YK.rightMark on 'عكس'. Second myth text 'An electron stops?' (coral, ✕ via YK.mythLine, wrongAt: YK.cueX('s2l16','بيوقف')) appears on cue 'electron' and stays to the line end + 1.5 s; YK.answerSlot(ctx, t, {at: YK.cueX('s2l16','لسه'), text: 'Both still spin', x: 300, y: 560}) held as long (numbers: 2 electrons).","tts_text":"ولا electron فيهم بيوقف spin؛ الاتنين لسه بيلِفّوا، إنما عكس بعض.","screen_text":"An electron stops? ✕  Both still spin ✓","pause_after_s":0.6},{"id":"s2l17","visual":"New picture: a second box beside the ↑↓ box, holding one ↑ (YK.electronBoxes(ctx, 1500, 560, {boxes: 1, electrons: 1, size: 220, labelPos: 'none'})) on cue 'لوحده'; the ↑↓ box dims to 50%. Text panel: YK.termCard(ctx, 96, 420, {term: 'unpaired electron', align: 'left', p: from cue 'unpaired'}) + the ↑ arrow (YK.spinArrow) beside it.","tts_text":"أما الـ electron اللي لوحده في الـ orbital، اسمه unpaired electron كده.","screen_text":"unpaired electron (↑)","pause_after_s":0.4},{"id":"s2l18","visual":"Lesson definition wording ('Its magnetic effect is not cancelled'): field arcs grow and stay around the single-↑ box on cue 'magnetic' (gold glow ring on the ↑, G31); the paperclip from s2l6 drifts toward it on 'بيفضل', while the ↑↓ box beside it keeps no arcs. YK.fpara (40) under the term card.","tts_text":"والـ unpaired electron ده الـ magnetic effect بتاعه بيفضل، عشان مالوش شريك يلغيه.","screen_text":"unpaired electron ↑: its magnetic effect is not cancelled","pause_after_s":0.6},{"id":"s2l19","visual":"Side-by-side summary of the idea (two boxes, labels under them via YK.tag): 'pair' under ↑↓ (no arcs) on cue 'pair', 'unpaired' under ↑ (arcs, gold ring) on cue 'unpaired'. Text panel: YK.fpara (44) two lines, each lighting on its cue.","tts_text":"يعني الـ pair تأثيره بيروح، والـ unpaired لوحده تأثيره بيفضل موجود.","screen_text":"↑↓ pair: effects cancel · ↑ unpaired: effect stays","pause_after_s":1},{"id":"s3l2","visual":"Stage: one empty box YK.electronBoxes(ctx, 1150, 560, {boxes: 1, electrons: 0, size: 240, labelPos: 'none'}) on cue 'orbital'; a counter tag YK.tag 'Electrons added: 0' (36) top-right of the stage (the lesson's interact label); three cyan electron dots wait at the right edge on cue 'electrons' (numbers: 1, 0). Text panel: YK.list step header 'Empty orbital: add electrons one by one'.","tts_text":"عندنا orbital فاضي، وهنحط فيه electrons واحد واحد.","screen_text":"Empty orbital: add electrons one by one","pause_after_s":0.4},{"id":"s3l3","visual":"Step 1: one dot flies in (YK.flyer arc, trail) on cue 'بيدخل' and becomes ↑ (cyan, YK.electronBoxes electrons: 1); counter 'Electrons added: 1'; field arcs + gold ring around the box on 'باين'. YK.list item 1 '1st electron: ↑ → an unpaired electron' on cue 'unpaired'.","tts_text":"أول electron بيدخل لوحده، فهو unpaired electron، وتأثيره المغناطيسي باين.","screen_text":"1st electron: ↑ → an unpaired electron","pause_after_s":0.4},{"id":"s3l4","visual":"Step 2: the second dot flies in on cue 'يدخل' and becomes ↓ pink (electrons: ['↑↓']) on cue 'opposite'; counter 'Electrons added: 2' (numbers: 1, 2). YK.list item 2 '2nd electron: same orbital, spin opposite ↓'.","tts_text":"تاني electron يدخل نفس الـ orbital، والـ spin بتاعه opposite للأول.","screen_text":"2nd electron: same orbital, spin opposite ↓","pause_after_s":0.4},{"id":"s3l5","visual":"The gold YK.bracket of s2l14 redraws around the box on cue 'pair'; field arcs and gold ring fade out on cue 'لغت'. YK.list item 3 '↑↓: a pair · magnetic effects cancel'.","tts_text":"كده بقوا pair، والـ magnetic effects بتاعتهم لغت بعض.","screen_text":"↑↓: a pair · magnetic effects cancel","pause_after_s":0.4},{"id":"s3l6","visual":"Step 3: the third dot flies toward the box on cue 'تالت' and bounces off the top edge (YK.flyer p reverses) on 'مينفعش'; YK.wrongMark small at the bounce point; counter 'Electrons added: 3' (numbers: 3, 2). YK.list item 4 '3rd electron: not in this orbital' (no strike-through).","tts_text":"طب تالت electron؟ مينفعش يدخل هنا، عشان الـ orbital فيه two خلاص.","screen_text":"3rd electron: not in this orbital ✕","pause_after_s":0.4},{"id":"s3l7","visual":"A second empty box slides in to the right (YK.electronBoxes(ctx, 1500, 560, {boxes: 1, size: 240, labelPos: 'none'})) on cue 'orbital'; the dot lands as ↑ on cue 'unpaired' with field arcs + gold ring (the lesson's interact final state: 'first orbital' ↑↓, 'next orbital' ↑; numbers: 2 orbitals). YK.list item 5 '→ another orbital: ↑ unpaired electron'. Which orbital electrons take first in a sublevel is NOT shown (Hund's rule, chapter).","tts_text":"فبيروح orbital تاني جنبه، ويبقى هناك unpaired electron لوحده.","screen_text":"→ another orbital: ↑ unpaired electron","pause_after_s":0.8},{"id":"s3l8","visual":"Self-check on a NEW case (↓↓ and a lone ↓ were never shown): stage clears to three boxes in a row, A / B / C (YK.electronBoxes size 200 at x 1000 / 1307 / 1614): ['↑↓'], ['↓↓'] (two pink ↓ drawn with YK.spinArrow by the page, the kit's electrons array does not draw ↓↓), ['↓']. YK.predictCard(ctx, t, {at: YK.cue('s3l8'), until: YK.cue('s3l9') + 0.4, think: YK.cueEnd('s3l8'), end: YK.cue('s3l9'), kind: 'QUICK CHECK', q: 'Which orbital breaks the Pauli principle?'}); YK.checkPause(ctx, 1307, 860, {t, start: YK.cueEnd('s3l8'), dur: 4}) through the silence; only the question shows (no answer, no hint).","tts_text":"دورك: أنهي orbital فيهم بيكسر الـ Pauli principle؟ وقّف الفيديو وفكّر.","screen_text":"Your turn: which orbital breaks the Pauli principle? [↑↓]  [↓↓]  [↓]","pause_after_s":4},{"id":"s3l9","visual":"Answer: box B gets YK.wrongMark and a coral outline on cue 'الإجابة' (held to the end of the segment); its two ↓ arrows pulse together on 'نفس' (numbers: 2 arrows). YK.answerSlot(ctx, t, {at: YK.cueX('s3l9','الإجابة'), text: '[↓↓]: same spin direction', x: 300, y: 600, color: C.mint}).","tts_text":"الإجابة: اللي فيه سهمين لتحت، عشان الـ spin بتاعهم في نفس الاتجاه.","screen_text":"[↓↓] ✕ same spin direction","pause_after_s":0.4},{"id":"s3l10","visual":"Reason: the Pauli card from s2l11–s2l12 returns small in the text panel (YK.termCard, keys 'opposite spins' gold on cue 'opposite'); box A (↑↓) gets YK.rightMark on cue 'opposite' as the model (numbers: 2, 1).","tts_text":"والـ Pauli principle بيطلب opposite spins لما two electrons يقعدوا في نفس الـ orbital مع بعض.","screen_text":"Pauli principle: two in one orbital → opposite spins","pause_after_s":0.4},{"id":"s3l11","visual":"Box A YK.rightMark + YK.tag 'pair' on cue 'pair'; box C YK.rightMark + YK.tag 'unpaired electron' on cue 'unpaired' with field arcs and gold ring (callback to the ↓ myth: a lone ↓ is a normal unpaired electron). Box B keeps its ✕.","tts_text":"أما الـ pair ده تمام، والسهم اللي لتحت لوحده ده unpaired electron عادي.","screen_text":"[↑↓] ✓ a pair  ·  [↓] ✓ an unpaired electron","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هتستخدمه فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, \"Hund's rule and orbital-box diagrams\", {kind: 'concept', align: 'left'}) (map title_en exactly) on cue 'Hund's'; beside it a row of three empty boxes (YK.electronBoxes boxes: 3, electrons: 0, labelPos: 'none') with ↑ and ↓ arrow icons waiting above them on cue 'المربعات' (no filling shown: the order is the dependent's content; numbers: 3 boxes).","tts_text":"في الفصل هتقابل الـ Hund's rule والـ orbital-box diagrams، المربعات والأسهم دي.","screen_text":"Hund's rule and orbital-box diagrams","pause_after_s":0.4},{"id":"s4l3","visual":"A YK.tag '?' (gold) pulses over the three empty boxes on cue 'ترتيب'; YK.fpara 'Order in which electrons take orbitals: in the chapter' (40, textDim) under the chip. Nothing is filled.","tts_text":"وهتعرف فيها الـ electrons بتاخد الـ orbitals بأي ترتيب.","screen_text":"Order in which electrons take orbitals: in the chapter","pause_after_s":0.4},{"id":"s4l4","visual":"YK.tag 'electronic configurations' (40) on cue 'electronic'; YK.tag 'orbital: 2 electrons at most' (40, cyan) with a small ↑↓ box on cue 'two' (number: 2).","tts_text":"وفي كتابة الـ electronic configurations، هتحتاج إن الـ orbital ياخد two electrons بالكتير.","screen_text":"electronic configurations · orbital: 2 electrons at most","pause_after_s":0.4},{"id":"s4l5","visual":"Third YK.chip(ctx, 820, 700, 'Paramagnetic and diamagnetic substances', {kind: 'concept', align: 'left'}) (in-book, Ch.1 '4-The Magnetic properties', pp.13–14) on cue 'paramagnetic'; a single-↑ box with a gold ring on cue 'unpaired'. No attraction/repulsion shown (the chapter teaches it).","tts_text":"وفي الـ paramagnetic والـ diamagnetic substances، هتشوف الـ unpaired electron بيعمل إيه هناك.","screen_text":"Paramagnetic and diamagnetic substances · unpaired electron ↑","pause_after_s":0.6},{"id":"s4l6","visual":"Recap (s4l6–s4l8 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l6'), until: YK.cue('s4l8'), title: 'Recap', line: 'spin → electron = a magnet · ↑ or ↓', pulse: [{word: 'spin', at: YK.cueX('s4l6','spin')}, {word: 'magnet', at: YK.cueX('s4l6','magnet')}]}); stage: the spinning sphere with its small magnet (s2l4) returns; ↑ and ↓ drawn with YK.spinArrow (number: 2 directions).","tts_text":"الخلاصة: الـ spin بيخلّي الـ electron زي magnet، وليه اتجاهين، لفوق ولتحت.","screen_text":"spin → electron = a magnet · ↑ or ↓","pause_after_s":0.4},{"id":"s4l7","visual":"Same recap card, second line added on cue 'pair'; stage: the two boxes of s2l19 (↑↓ no arcs, ↑ arcs + gold ring), 'stays' lights on cue 'بيفضل'.","tts_text":"الـ pair تأثيرهم بيلغي بعض، والـ unpaired electron تأثيره بيفضل.","screen_text":"↑↓ pair: cancel · ↑ unpaired electron: stays","pause_after_s":0.6},{"id":"s4l8","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Pauli principle', line: 'One orbital: two electrons at most, opposite spins.', t, pulse: [{word: 'two', at: YK.cueX('s4l8','two')}, {word: 'opposite', at: YK.cueX('s4l8','opposite')}]}) with a ↑↓ box (YK.electronBoxes) as its formula slot (numbers: 1 orbital, 2 electrons). Holds to the end (no fade to black).","tts_text":"يعني الـ Pauli principle: two electrons بالكتير في الـ orbital، وليهم opposite spins كمان.","screen_text":"One orbital: two electrons at most, opposite spins.","pause_after_s":1.5}],"logline":"هتفهموا يعني إيه الـ spin، وليه الـ orbital الواحد ياخد اتنين electrons بالكتير، ولازم يكون ليهم opposite spins.","segments":[{"id":"s1","title":"Magnets, electrons and orbitals","concept_id":"atom.electron-spin-pauli"},{"id":"s2","title":"Spin and the Pauli principle","concept_id":"atom.electron-spin-pauli"},{"id":"s3","title":"Filling one orbital","concept_id":"atom.electron-spin-pauli"},{"id":"s4","title":"Where Chapter 1 uses spin and 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على مغناطيس التلاجة بيلزق في الباب من\nغير صَمغ\nولو قرّبت منه مشبك ورق بيشِدّه ناحيته من\nغير ما يلمسه\nولو حطّينا مغناطيسين جنب بعض في نفس\nالاتجاه الشد بيزيد\nإنما لو عكس بعض تأثيرهم بيلغي بعضه والمشبك\nيدوب بيتحرك\nدلوقتي ندخل جوه حتة صغيرة جدًا من المادة\nاسمها الذرة\nفي نص الذرة فيه مركز صغير اسمه الـ nucleus\nيعني النواة\nوحواليه بتتحرك electrons جسيمات صغيرة جدًا\nشُحنتها سالبة\nوالـ orbital هو المنطقة حوالين الـ nucleus\nاللي الـ electron غالبًا بيكون فيها\nخلّي بالك الـ orbital مش مسار دايري زي\nالكواكب ده منطقة\nوعشان نرسم الـ orbital بسهولة بنرسمه مربع\nصغير زي ده\nيبقى كده عرفنا الـ nucleus والـ electron\nوالـ orbital كويس\nتخيّل نَحلة لعبة بتلِف حوالين نفسها بسرعة\nعلى الأرض\nوالـ electron كمان بيعمل spin يعني بيلِف\nحوالين نفسه\nوالـ spin ده بيخلّي الـ electron يتصرّف زي\nmagnet صغير يعني مغناطيس\nوالـ magnet ده بيعمل حواليه magnetic field\nيعني منطقة بيبان فيها تأثيره\nوالشد أو الزق ده اسمه الـ magnetic effect\nيعني التأثير المغناطيسي\nوالـ spin ليه اتجاهين وبنرسمهم سهم لفوق\nوسهم لتحت\nناس فاكرة إن السهم اللي لتحت ده electron\nناقص أو مختلف وده غلط\nده electron عادي زي التاني بالظبط إنما\nبيعمل spin في الاتجاه العكسي\nطب لو two electrons في one orbital الـ\nmagnetic effects بتاعتهم هيحصلها إيه\nالـ Pauli principle بيقول كل orbital ياخد\ntwo electrons بالكتير\nولازم يكون ليهم opposite spins يعني واحد\nسهم لفوق وواحد لتحت\nفالـ magnets الصغيرين بيبصّوا عكس بعض والـ\nmagnetic effects بتلغي بعض\nوالـ two اللي في one orbital كده بنسميهم\npair يعني جوز\nناس بتفتكر إن التأثيرين بيتجمعوا والـ\norbital يبقى مغناطيس أقوى غلط\nولا electron فيهم بيوقف spin الاتنين لسه\nبيلِفّوا إنما عكس بعض\nأما الـ electron اللي لوحده في الـ orbital\nاسمه unpaired electron كده\nوالـ unpaired electron ده الـ magnetic\neffect بتاعه بيفضل عشان مالوش شريك يلغيه\nيعني الـ pair تأثيره بيروح والـ unpaired\nلوحده تأثيره بيفضل موجود\nعندنا orbital فاضي وهنحط فيه electrons\nواحد واحد\nأول electron بيدخل لوحده فهو unpaired\nelectron وتأثيره المغناطيسي باين\nتاني electron يدخل نفس الـ orbital والـ\nspin بتاعه opposite للأول\nكده بقوا pair والـ magnetic effects\nبتاعتهم لغت بعض\nطب تالت electron مينفعش يدخل هنا عشان الـ\norbital فيه two خلاص\nفبيروح orbital تاني جنبه ويبقى هناك\nunpaired electron لوحده\nدورك أنهي orbital فيهم بيكسر الـ Pauli\nprinciple وقّف الفيديو وفكّر\nالإجابة اللي فيه سهمين لتحت عشان الـ spin\nبتاعهم في نفس الاتجاه\nوالـ Pauli principle بيطلب opposite spins\nلما two electrons يقعدوا في نفس الـ\norbital مع بعض\nأما الـ pair ده تمام والسهم اللي لتحت\nلوحده ده unpaired electron عادي\nطب الكلام ده هتستخدمه فين في الفصل\nفي الفصل هتقابل الـ Hund's rule والـ\norbital-box diagrams المربعات والأسهم دي\nوهتعرف فيها الـ electrons بتاخد الـ\norbitals بأي ترتيب\nوفي كتابة الـ electronic configurations\nهتحتاج إن الـ orbital ياخد two electrons\nبالكتير\nوفي الـ paramagnetic والـ diamagnetic\nsubstances هتشوف الـ unpaired electron\nبيعمل إيه هناك\nالخلاصة الـ spin بيخلّي الـ electron زي\nmagnet وليه اتجاهين لفوق ولتحت\nالـ pair تأثيرهم بيلغي بعض والـ unpaired\nelectron تأثيره بيفضل\nيعني الـ Pauli principle two electrons\nبالكتير في الـ orbital وليهم opposite\nspins كمان","countable":false,"session_id":"chem-s3-en.ch1.s1","session_no":1,"session_ord":75,"see_also":[{"item_id":"chem-s3-en.lesson-te.position-in-periodic-table","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Transition elements in the periodic table","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":113.31,"kind":"pause_question","spec":{"answer":"بيلغوا بعض: الـ Pauli principle بيقول الـ orbital ياخد 2 electrons بالكتير، بـ opposite spins (سهم لفوق وسهم لتحت).","prompt":"اتنين electrons في orbital واحد: الـ magnetic effects بتاعتهم بيحصلها إيه؟","options":[{"id":"a","text":"بيلغوا بعض","correct":true},{"id":"b","text":"بيزيدوا، والـ orbital يبقى أقوى","correct":false},{"id":"c","text":"واحد من الـ electrons بيبطّل spin","correct":false}],"answer_t_s":116.6,"concept_id":"atom.electron-spin-pauli"},"content_lang":"ar-EG"},{"id":"think-2","t_s":211.04,"kind":"pause_question","spec":{"answer":"[↓↓]: الاتنين spin في نفس الاتجاه، واتنين في orbital واحد لازم يكون ليهم opposite spins.","prompt":"أنهي orbital فيهم بيكسر الـ Pauli principle: [↑↓] ولا [↓↓] ولا [↓]؟","options":[{"id":"a","text":"[↓↓]","correct":true},{"id":"b","text":"[↑↓]","correct":false},{"id":"c","text":"[↓]","correct":false}],"answer_t_s":215.52,"concept_id":"atom.electron-spin-pauli"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-atom.electron-spin-pauli"]},{"id":"chem-s3-en.video-walkthrough-phys.waves-light","kind":"walkthrough","version":5,"ord":76,"content_lang":"ar-EG","primary_concept_id":"phys.waves-light","concepts":[{"concept_id":"phys.waves-light","role":"primary"}],"title":"Light and waves: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-phys.waves-light v2 (s1 hook: what carries the Sun's energy — distractors hot air / sound, empty space has no air; s2 crests + Wavelength KeyTerm 'The distance between two neighbouring crests of a wave.'; s3 Frequency KeyTerm 'The number of complete waves that pass a point in one second. Its unit is the hertz (Hz).', 'In empty space, all light travels at the same speed', slider: shorter wavelength → higher frequency; s4 check red ~700 nm vs blue ~450 nm + fill-blank; s5 recap 'For light, a shorter wavelength means a higher frequency', 'Next: light is only one member of a bigger family of waves'); en layer feedback ('bigger wave, bigger number'; 'same speed → same frequency'); concept phys.waves-light v2 (no recorded misconceptions: s2 refutes the lesson's three: hot air/sound carries the Sun's energy (s2l3), longer wave → higher frequency (s2l14–s2l15), same speed → same frequency (s2l16–s2l17)). Book: no section on waves (prerequisite); Ch.1 p.5 uses UV (TiO2 sunscreen) via phys.em-spectrum — not named in s4 to avoid new facts. Dependent named in s4: phys.em-spectrum 'Electromagnetic radiation (UV, X-rays, gamma)' (map title_en exactly; its terms are named, nothing about them is taught; «زي» = 'such as', not a complete list, rule chem-s3-en.ch1.fact.prereq-scoping). Terms (defined at first use): s1 wave, energy, crest (3); s2 light, wavelength, frequency, hertz; s3/s4 none new ('red light'/'blue light' are colours of light; s4 chip = dependent title). Speed of light is 'the same' only 'in empty space' every time (rule prereq-scoping); no 3 × 10^8 m/s and no nm values (keeps s3 free of new units; the self-check uses 'longer/shorter wavelength' instead of the 700/450 nm figures). Worked example: two drawn waves, same speed, the 2nd with half the wavelength: 2 vs 4 crests per second → 2 vs 4 hertz (labelled on screen 'drawing, not real light values'). Self-check (new case): red light (longer wavelength) vs blue light — which has the higher frequency; answer blue + reason (same speed in empty space, more crests per second). Predicts: s2l2 (3.0 s), s2l11 (3.0 s), s3l9 (4.0 s). not-in-source: s1l2–s1l6 stone-in-a-pond anchor (rings spread, a far leaf bobs up and down, the wave carries energy to it); s3l3–s3l6 the drawn 2-vs-4-crests example (consistent with the lesson's 'same speed: shorter waves mean more waves pass each second'). Estimate: 44 lines, ~485 words at ~2.4 words/s ≈ 202 s + 39 s pauses ≈ 241 s (≈ 4.0 min); recap s4l5–s4l7 ≈ 15 s.","title":"Light and waves: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor: a small grey stone (page-local ctx path, C.steelDark rim) falls from the top of the stage on cue 'رميت' and hits the pond centre on cue 'بركة' (small splash: 6 YK.dot droplets, seeded YK.rng). Text panel: YK.fpara 'A small stone, still water' (44).","tts_text":"تخيّل إنك رميت حجر صغير في مَيّة بركة هادية.","screen_text":"A small stone, still water","pause_after_s":0.4},{"id":"s1l3","visual":"Concentric rings (page-local ctx.arc, C.cyan, alpha fading with radius) are born at the impact point from cue 'دواير' and keep growing outward with t (radius = speed × (t − birth)); new ring every 0.6 s. Text panel: YK.fpara 'Rings spread out on the water' (44).","tts_text":"هتلاقي دواير بتطلع من مكان الحجر، وتِجري لبرّه على سطح المية.","screen_text":"Rings spread out on the water","pause_after_s":0.4},{"id":"s1l4","visual":"One ring is highlighted gold (G5 focus) as it travels on cue 'بتتنقل'; YK.tag 'wave' (40) rides on it. Text panel: YK.termCard(ctx, 96, 420, {term: 'wave', align: 'left', p: from cue 'wave'}).","tts_text":"الحركة دي اللي بتتنقل على سطح المية اسمها wave، يعني موجة.","screen_text":"wave","pause_after_s":0.4},{"id":"s1l5","visual":"A leaf (page-local ctx path, C.mint at 70%) floats near the pond edge from cue 'ورقة'; when the gold ring reaches it (cue 'توصلها') the leaf bobs up and down (y = A·sin) while staying in place. Text panel: YK.fpara 'The wave reaches a far leaf: it bobs up and down' (40).","tts_text":"ولو فيه ورقة شجر بعيد، الـ wave توصلها فتطلّعها وتنزّلها.","screen_text":"The wave reaches a far leaf: it bobs up and down","pause_after_s":0.4},{"id":"s1l6","visual":"A small gold glow (YK.glowCircle, C.gold, alpha 0.5) travels with the highlighted ring and flashes into the leaf on cue 'energy'. Text panel: YK.termCard(ctx, 96, 560, {term: 'energy', align: 'left', p: from cue 'energy'}) + YK.fpara 'the wave carries energy' (40) under it; the wave card dims to 35%.","tts_text":"يعني الـ wave شايلة energy، طاقة تقدر تحرّك الورقة من بعيد.","screen_text":"energy · the wave carries energy","pause_after_s":0.4},{"id":"s1l7","visual":"Camera tilts to a side view (YK.camera 1.0 s, inOut): the pond surface becomes a horizontal wave drawn with YK.wave(ctx, 820, 600, 1800, 600, {t, amp: 70, wl: 320, color: C.cyan, speed: 0.6}); a gold dot sits on one high point and YK.tag 'crest' (40) points to it on cue 'crest'. Text panel: YK.termCard(ctx, 96, 420, {term: 'crest', def: 'a high point of a wave', align: 'left', p: from cue 'crest'}).","tts_text":"النقطة العالية في الـ wave اسمها crest، يعني قمة.","screen_text":"crest: a high point of a wave","pause_after_s":0.4},{"id":"s1l8","visual":"Same YK.wave keeps moving left → right; a small gold dot marks every crest in turn (three dots light one after another on cue 'crests'), the leaf (small) rides the wave at x 1200 bobbing up and down. Text panel: YK.fpara 'Side view: crests one after another' (44).","tts_text":"ولو بصّينا على الـ wave من الجنب، هنشوف crests ورا بعض.","screen_text":"Side view: crests one after another","pause_after_s":0.4},{"id":"s1l9","visual":"Micro-recap: the three term cards collapse into YK.chip(ctx, 96, y, label, {kind: 'concept', align: 'left'}) at y 300 / 400 / 500 on cues 'wave' / 'crest' / 'energy'; the side-view wave keeps moving.","tts_text":"يبقى معانا الـ wave والـ crest والـ energy، خلّيهم في بالك.","screen_text":"wave · crest · energy","pause_after_s":1},{"id":"s2l2","visual":"Lesson hook (step s1): stage = a Sun disc (page-local, C.gold → C.molten radial gradient, left of the stage) and a small Earth (page-local disc) far right, a long dark gap between them on cue 'الشمس'. YK.predictCard(ctx, t, {at: YK.cue('s2l2'), until: YK.cue('s2l3') + 0.4, think: YK.cueEnd('s2l2'), end: YK.cue('s2l3'), kind: 'PREDICT', q: \"What carries the Sun's energy to you?\"}); only the question shows during the pause.","tts_text":"الشمس بتدفّي وشك من بعيد جدًا؛ إيه اللي بيوصّل الـ energy دي؟ فكّر.","screen_text":"PREDICT: What carries the Sun's energy to you?","pause_after_s":3},{"id":"s2l3","visual":"Myth (lesson hook distractors): YK.mythLine(ctx, t, {at: YK.cue('s2l3'), wrongAt: YK.cueX('s2l3','سخن'), until: YK.cueEnd('s2l4') + 1.5, text: 'Hot air or sound?', x: 96, y: 300, size: 48}) coral with ✕ for its whole visible time; on the stage a small puff of air particles (YK.particles seed 4, alpha 0.3) tries to leave the Sun and stops at its edge on cue 'هوا', marked YK.wrongMark; the gap gets a YK.tag 'Empty space: no air' (36) on cue 'فاضي'.","tts_text":"بين الشمس والأرض فضا فاضي، مفيهوش هوا، فلا هوا سُخن ولا صوت يعدّي.","screen_text":"Hot air or sound? ✕ Empty space: no air","pause_after_s":0.4},{"id":"s2l4","visual":"Fix (held ≥ the myth): a YK.wave(ctx, sunX, 540, earthX, 540, {t, p: prog from cue 'light' over 1.2 s, amp: 30, wl: 120, color: C.gold, speed: 1}) runs from the Sun to the Earth; a gold glow rides it (energy) and the Earth's day side brightens on cue 'energy'. YK.answerSlot(ctx, t, {at: YK.cueX('s2l4','light'), text: 'light: travels as waves that carry energy', x: 300, y: 560}); YK.termCard 'light' small above it.","tts_text":"اللي بيوصّلها هو الـ light، يعني الضوء، وبيمشي على شكل waves شايلة energy معاها.","screen_text":"light: travels as waves that carry energy ✓","pause_after_s":0.4},{"id":"s2l5","visual":"The empty gap glows faintly as the gold wave keeps crossing it (no particles in the gap) on cue 'الفاضي'; YK.tag 'even through empty space' (40) under the wave. The myth line exits at its until.","tts_text":"والـ waves دي بتعدّي حتى في الفضا الفاضي، من غير هوا.","screen_text":"waves · even through empty space","pause_after_s":0.6},{"id":"s2l6","visual":"New picture: one side-view wave YK.wave(ctx, 820, 600, 1800, 600, {t: 0, amp: 70, wl: 320, color: C.molten}) frozen; two neighbouring crests get gold dots on cue 'crests'; a double-headed arrow (page-local, drawn left → right) spans them on cue 'المسافة' with YK.tag 'wavelength' on cue 'wavelength' (the lesson figure: 'The arrow marks one wavelength'). Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 340, {term: 'Wavelength', def: 'The distance between two neighbouring crests of a wave.', keys: ['two neighbouring crests'], align: 'left', p: from cue 'wavelength'}) (number on screen: 2).","tts_text":"المسافة بين two crests جنب بعض اسمها wavelength، يعني طول الموجة.","screen_text":"Wavelength: The distance between two neighbouring crests of a wave.","pause_after_s":0.8},{"id":"s2l7","visual":"The wave starts moving again (speed 1); a vertical dashed gate line (page-local, C.textDim) at x 1300 appears on cue 'نقطة' (number: 1 point); each crest that crosses the gate flashes gold and a counter label 'Crests passed: n' (YK.label 40, n computed from t, deterministic) ticks up from cue 'وعِدّ'. Text panel: YK.fpara 'Count the crests that pass one point' (44).","tts_text":"دلوقتي اقف عند نقطة واحدة، وعِدّ الـ crests اللي بتعدّي قدامك.","screen_text":"Count the crests that pass one point","pause_after_s":0.4},{"id":"s2l8","visual":"A one-second timer ring (YK.checkPause-style ring drawn by the page, 1 s sweep, C.gold) runs on cue 'one' while the gate counter counts within that second (number: 1). Definition card (lesson KeyTerm wording, first sentence): YK.termCard(ctx, 96, 340, {term: 'Frequency', def: 'The number of complete waves that pass a point in one second.', keys: ['in one second'], align: 'left', p: from cue 'frequency'}).","tts_text":"عدد الـ waves الكاملة اللي بتعدّي في one second اسمه frequency كده.","screen_text":"Frequency: The number of complete waves that pass a point in one second.","pause_after_s":0.6},{"id":"s2l9","visual":"The counter label becomes 'waves per second' and YK.tag 'hertz' (44, gold outline) slides in under the Frequency card on cue 'hertz' (lesson: 'Its unit is the hertz (Hz)'). Stage unchanged (moving wave + gate).","tts_text":"ووحدة الـ frequency اسمها hertz، يعني كام wave في الثانية.","screen_text":"unit of frequency: hertz","pause_after_s":0.4},{"id":"s2l10","visual":"New picture: three light waves of different wavelengths (YK.wave, colours C.coral-red, C.mint-green, violet; wl 360 / 260 / 180) start together at the left of a dark 'empty space' band and their fronts (small gold markers) move right at the SAME px/s (each wave's speed parameter = constant / wl) on cue 'بنفس'; the fronts stay lined up. Text panel: YK.fpara 'In empty space, all light travels at the same speed' (44) with 'In empty space' in gold (rule: equal speed only in empty space).","tts_text":"وفي الفضا الفاضي، الـ light كله بيمشي بنفس السرعة بالظبط.","screen_text":"In empty space, all light travels at the same speed","pause_after_s":0.6},{"id":"s2l11","visual":"YK.predictCard(ctx, t, {at: YK.cue('s2l11'), until: YK.cue('s2l12') + 0.4, think: YK.cueEnd('s2l11'), end: YK.cue('s2l12'), kind: 'PREDICT', q: 'Same speed, shorter waves. Frequency?'}); stage: two waves stacked (long wl 360 top, short wl 180 bottom), both frozen, the gate line through both; only the question shows during the pause.","tts_text":"طب لو الـ waves بقت أقصَر والسرعة زي ما هي، الـ frequency هتعمل إيه؟","screen_text":"PREDICT: same speed, shorter waves. Frequency?","pause_after_s":3},{"id":"s2l12","visual":"Both waves move at the same px/s from cue 'بتعدّي'; two gate counters (YK.label, page-computed) tick: the short wave's counter climbs faster; a 1-second ring sweeps once on 'الثانية' and freezes the counts. Text panel: YK.fpara 'Shorter waves → more crests pass each second' (44).","tts_text":"الـ waves الأقصَر بتعدّي منها crests أكتر في نفس الثانية.","screen_text":"Shorter waves → more crests pass each second","pause_after_s":0.4},{"id":"s2l13","visual":"Rule card: YK.recapCard-style panel (YK.panel + YK.fpara 48) 'For light: shorter wavelength → higher frequency' with the arrow drawn gold; on the stage the short wave glows gold on cue 'الأقصر' and its counter pulses on 'أعلى'. YK.rightMark.","tts_text":"يعني في الـ light، الـ wavelength الأقصَر معناها frequency أعلى.","screen_text":"For light: shorter wavelength → higher frequency","pause_after_s":0.6},{"id":"s2l14","visual":"Lesson misconception ('bigger wave, bigger number'): YK.mythLine(ctx, t, {at: YK.cue('s2l14'), wrongAt: YK.cueX('s2l14','غلط'), until: YK.cueEnd('s2l15') + 1.5, text: 'Longer wave → higher frequency?', x: 96, y: 300, size: 48}) coral with ✕ for its whole visible time; the long wave gets a coral outline and YK.wrongMark.","tts_text":"ناس بتفتكر إن الـ wave الأطوَل ليها frequency أعلى، وده غلط.","screen_text":"Longer wave → higher frequency? ✕","pause_after_s":0.4},{"id":"s2l15","visual":"Fix held ≥ the myth: the two frozen counters from s2l12 come back side by side; the long wave's smaller count lights on cue 'أقل'#1; YK.answerSlot(ctx, t, {at: YK.cueX('s2l15','فالـ'), text: 'Longer wavelength → lower frequency', x: 300, y: 600}).","tts_text":"الـ wavelength الأطوَل بيعدّي منه crests أقل، فالـ frequency بتبقى أقل.","screen_text":"Longer wavelength → fewer crests per second → lower frequency ✓","pause_after_s":0.4},{"id":"s2l16","visual":"Second misconception (lesson check option c): YK.mythLine(ctx, t, {at: YK.cue('s2l16'), wrongAt: YK.cueX('s2l16','غلط'), until: YK.cueEnd('s2l17') + 1.5, text: 'Same speed → same frequency?', x: 96, y: 300, size: 48}) with ✕; stage: the two waves with lined-up fronts (same speed) and two '=' tags (page-drawn) between their counters, the lower one marked YK.wrongMark.","tts_text":"وناس تانية فاكرة إن نفس السرعة معناها نفس الـ frequency؛ غلط برضه.","screen_text":"Same speed → same frequency? ✕","pause_after_s":0.4},{"id":"s2l17","visual":"Fix: the lesson's slider idea as a picture: one wave whose wl tweens 360 → 180 (YK.tween) on cue 'تتغيّر'#1 while its front speed stays fixed; its gate counter rate rises on 'بتتغيّر'. YK.answerSlot(ctx, t, {at: YK.cueX('s2l17','بتتغيّر'), text: 'wavelength changes → frequency changes', x: 300, y: 600}).","tts_text":"السرعة ثابتة، إنما لما الـ wavelength تتغيّر، الـ frequency بتتغيّر معاها.","screen_text":"Same speed, but the wavelength changes → the frequency changes ✓","pause_after_s":1},{"id":"s3l2","visual":"Stage: two YK.wave rows, 'Wave 1' (top, wl 320, C.cyan) and 'Wave 2' (bottom, wl 160, C.violet), labels via YK.tag on cues 'الأولى' / 'والتانية' (numbers: 2 waves, 1, 2); their fronts move at the same px/s. A gate line crosses both at x 1300. YK.list step header in the text panel.","tts_text":"عندنا two waves، الأولى والتانية، وبيمشوا بنفس السرعة بالظبط.","screen_text":"Wave 1 and wave 2: same speed","pause_after_s":0.4},{"id":"s3l3","visual":"Step 1: wavelength arrows (page-local double arrows) appear on each row on cue 'wavelength'#1 / 'wavelength'#2; the wave-2 arrow is copied and laid twice under the wave-1 arrow to show half (numbers: 2, 1, 1/2). YK.list item 1 '2nd: wavelength = half of the 1st'.","tts_text":"الـ wavelength بتاعة التانية half الـ wavelength بتاعة الأولى بالظبط.","screen_text":"2nd: wavelength = half of the 1st","pause_after_s":0.4},{"id":"s3l4","visual":"Step 2: a 1-second ring sweeps (page-drawn) from cue 'one'; the wave-1 gate counter ticks 0 → 2 (crests flash gold at the gate) (numbers: 1, 2). YK.list item 2 'In one second, 1st wave: 2 crests pass'.","tts_text":"في one second، الـ wave الأولى بيعدّي منها two crests قدام النقطة.","screen_text":"In one second, 1st wave: 2 crests pass","pause_after_s":0.4},{"id":"s3l5","visual":"Step 3: replay of the same second for wave 2: its counter ticks 0 → 4 on cue 'four' (numbers: 2, 4); a '×2' tag (page-drawn, gold) between the two counters on 'الضعف'. YK.list item 3 'Same second, 2nd wave: 4 crests pass'.","tts_text":"وفي نفس الثانية، الـ wave التانية بيعدّي منها four crests، يعني الضعف.","screen_text":"Same second, 2nd wave: 4 crests pass","pause_after_s":0.4},{"id":"s3l6","visual":"Step 4: the counters turn into frequency labels YK.label 'frequency = 2 hertz' (wave 1) and 'frequency = 4 hertz' (wave 2) on cues 'two' / 'four' (numbers: 1, 2, 4). YK.list item 4. A small YK.tag 'drawing, not real light values' (32, textDim) under the stage.","tts_text":"يعني الـ frequency بتاعة الأولى two hertz، والتانية four hertz كده.","screen_text":"frequency: 1st = 2 hertz · 2nd = 4 hertz","pause_after_s":0.4},{"id":"s3l7","visual":"Conclusion: wave 2 row glows gold (focus), wave 1 dims to 35%; YK.list item 5 '2nd: shorter wavelength → higher frequency' with YK.rightMark on cue 'أعلى' (number: 2).","tts_text":"يبقى التانية الـ wavelength بتاعتها أقصَر، والـ frequency بتاعتها أعلى.","screen_text":"2nd: shorter wavelength → higher frequency","pause_after_s":0.8},{"id":"s3l8","visual":"Self-check on a NEW case (light colours, not the drawn waves of the example; lesson check s4 data: red about 700 nm, blue about 450 nm — numbers not shown): stage clears to two YK.wave rows, red (wl 280, '#F87171') on cue 'red' and blue (wl 180, '#60A5FA') on cue 'blue', both moving at the same px/s; YK.tag 'red light' / 'blue light' under them.","tts_text":"دورك: الـ red light الـ wavelength بتاعه أطوَل، والـ blue light أقصَر.","screen_text":"Your turn: red light: longer wavelength · blue light: shorter","pause_after_s":0.4},{"id":"s3l9","visual":"YK.predictCard(ctx, t, {at: YK.cue('s3l9'), until: YK.cue('s3l10') + 0.4, think: YK.cueEnd('s3l9'), end: YK.cue('s3l10'), kind: 'QUICK CHECK', q: 'Red or blue light: which has the higher frequency?'}); YK.checkPause(ctx, 1307, 880, {t, start: YK.cueEnd('s3l9'), dur: 4}); the waves freeze during the pause; no answer or hint shows.","tts_text":"مين فيهم الـ frequency بتاعه أعلى؟ وقّف الفيديو وفكّر.","screen_text":"Which has the higher frequency?","pause_after_s":4},{"id":"s3l10","visual":"Answer: the blue row gets YK.rightMark and a gold outline on cue 'الإجابة'; YK.answerSlot(ctx, t, {at: YK.cueX('s3l10','blue'), text: 'Blue light: shorter wavelength → higher frequency', x: 300, y: 560}).","tts_text":"الإجابة: الـ blue light، عشان الـ wavelength بتاعه أقصَر، فالـ frequency أعلى.","screen_text":"Blue light ✓ shorter wavelength → higher frequency","pause_after_s":0.4},{"id":"s3l11","visual":"Reason: both rows move again at the same px/s with gate counters; the blue counter climbs faster during a 1-second ring on cue 'بتعدّي' (numbers: 2 rows). Text panel reason line YK.fpara (40).","tts_text":"الاتنين بنفس السرعة في الفضا، فالـ crests الزرقا بتعدّي أكتر في الثانية.","screen_text":"Same speed in empty space: more crests pass each second","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 240, 'Electromagnetic radiation (UV, X-rays, gamma)', {kind: 'concept', align: 'left'}) (map title_en exactly) on cue 'electromagnetic'; the words 'UV', 'X-rays', 'gamma' in the chip pulse gold on their cues. No properties of these rays shown (the next lesson teaches them).","tts_text":"الدرس الجاي هو الـ electromagnetic radiation، زي الـ UV والـ X-rays والـ gamma كمان.","screen_text":"Electromagnetic radiation (UV, X-rays, gamma)","pause_after_s":0.4},{"id":"s4l3","visual":"The visible-light wave of s2l10 shrinks into one slot of an unlabelled row of empty slots (page-local rounded rects, textDim outline) on cue 'عيلة' (lesson 'Next: light is only one member of a bigger family of waves'; number: 1). Slots stay unlabelled.","tts_text":"وهناك هتلاقي الـ light واحد من عيلة waves كبيرة.","screen_text":"Light: one member of a bigger family of waves","pause_after_s":0.4},{"id":"s4l4","visual":"YK.tag 'wavelength' and 'frequency' (40) slide under the slot row on their cues; a gold arrow (page-drawn) sweeps along the row on 'ترتّب' without naming any member.","tts_text":"وهتحتاج الـ wavelength والـ frequency عشان ترتّب العيلة دي.","screen_text":"wavelength and frequency put the family in order","pause_after_s":0.6},{"id":"s4l5","visual":"Recap (s4l5–s4l7 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l5'), until: YK.cue('s4l7'), title: 'Light and waves', line: 'Light: waves that carry energy', pulse: [{word: 'waves', at: YK.cueX('s4l5','waves')}, {word: 'energy', at: YK.cueX('s4l5','energy')}]}); stage: the Sun → Earth gold wave of s2l4.","tts_text":"الخلاصة: الـ light بيمشي waves شايلة energy، حتى في الفضا.","screen_text":"Light: waves that carry energy","pause_after_s":0.4},{"id":"s4l6","visual":"Same recap card, second line on cue 'wavelength'; stage: the wavelength arrow (s2l6) on cue 'wavelength' and the gate counter (s2l8) on cue 'frequency' (number: 2).","tts_text":"الـ wavelength مسافة بين two crests، والـ frequency عدد الـ waves في الثانية.","screen_text":"wavelength: between 2 crests · frequency: waves per second","pause_after_s":0.6},{"id":"s4l7","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Light and waves', line: 'For light: shorter wavelength, higher frequency.', t, pulse: [{word: 'shorter', at: YK.cueX('s4l7','الأقصر')}, {word: 'higher', at: YK.cueX('s4l7','أعلى')}]}); holds to the end (no fade to black).","tts_text":"في الـ light: الـ wavelength الأقصَر، الـ frequency بتاعه أعلى.","screen_text":"For light: shorter wavelength, higher frequency.","pause_after_s":1.5}],"logline":"هتفهموا إزاي الـ light بيوصل waves شايلة energy، وتفرّقوا بين الـ wavelength والـ frequency، وتعرفوا مين أعلى من غير حفظ.","segments":[{"id":"s1","title":"A stone in still water","concept_id":"phys.waves-light"},{"id":"s2","title":"Wavelength and frequency of light","concept_id":"phys.waves-light"},{"id":"s3","title":"Two waves at the same speed","concept_id":"phys.waves-light"},{"id":"s4","title":"Where Chapter 1 uses light and 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إنك رميت حجر صغير في مَيّة بركة\nهادية\nهتلاقي دواير بتطلع من مكان الحجر وتِجري\nلبرّه على سطح المية\nالحركة دي اللي بتتنقل على سطح المية اسمها\nwave يعني موجة\nولو فيه ورقة شجر بعيد الـ wave توصلها\nفتطلّعها وتنزّلها\nيعني الـ wave شايلة energy طاقة تقدر تحرّك\nالورقة من بعيد\nالنقطة العالية في الـ wave اسمها crest\nيعني قمة\nولو بصّينا على الـ wave من الجنب هنشوف\ncrests ورا بعض\nيبقى معانا الـ wave والـ crest والـ energy\nخلّيهم في بالك\nالشمس بتدفّي وشك من بعيد جدًا إيه اللي\nبيوصّل الـ energy دي فكّر\nبين الشمس والأرض فضا فاضي مفيهوش هوا فلا\nهوا سُخن ولا صوت يعدّي\nاللي بيوصّلها هو الـ light يعني الضوء\nوبيمشي على شكل waves شايلة energy معاها\nوالـ waves دي بتعدّي حتى في الفضا الفاضي\nمن غير هوا\nالمسافة بين two crests جنب بعض اسمها\nwavelength يعني طول الموجة\nدلوقتي اقف عند نقطة واحدة وعِد الـ crests\nاللي بتعدّي قدامك\nعدد الـ waves الكاملة اللي بتعدّي في one\nsecond اسمه frequency كده\nووحدة الـ frequency اسمها hertz يعني كام\nwave في الثانية\nوفي الفضا الفاضي الـ light كله بيمشي بنفس\nالسرعة بالظبط\nطب لو الـ waves بقت أقصَر والسرعة زي ما هي\nالـ frequency هتعمل إيه\nالـ waves الأقصَر بتعدّي منها crests أكتر\nفي نفس الثانية\nيعني في الـ light الـ wavelength الأقصَر\nمعناها frequency أعلى\nناس بتفتكر إن الـ wave الأطوَل ليها\nfrequency أعلى وده غلط\nالـ wavelength الأطوَل بيعدّي منه crests\nأقل فالـ frequency بتبقى أقل\nوناس تانية فاكرة إن نفس السرعة معناها نفس\nالـ frequency غلط برضه\nالسرعة ثابتة إنما لما الـ wavelength\nتتغيّر الـ frequency بتتغيّر معاها\nعندنا two waves الأولى والتانية وبيمشوا\nبنفس السرعة بالظبط\nالـ wavelength بتاعة التانية half الـ\nwavelength بتاعة الأولى بالظبط\nفي one second الـ wave الأولى بيعدّي منها\ntwo crests قدام النقطة\nوفي نفس الثانية الـ wave التانية بيعدّي\nمنها four crests يعني الضعف\nيعني الـ frequency بتاعة الأولى two hertz\nوالتانية four hertz كده\nيبقى التانية الـ wavelength بتاعتها أقصَر\nوالـ frequency بتاعتها أعلى\nدورك الـ red light الـ wavelength بتاعه\nأطوَل والـ blue light أقصَر\nمين فيهم الـ frequency بتاعه أعلى وقّف\nالفيديو وفكّر\nالإجابة الـ blue light عشان الـ wavelength\nبتاعه أقصَر فالـ frequency أعلى\nالاتنين بنفس السرعة في الفضا فالـ crests\nالزرقا بتعدّي أكتر في الثانية\nطب الكلام ده هيفيدك فين في الفصل\nالدرس الجاي هو الـ electromagnetic\nradiation زي الـ UV والـ X-rays والـ gamma\nكمان\nوهناك هتلاقي الـ light واحد من عيلة waves\nكبيرة\nوهتحتاج الـ wavelength والـ frequency عشان\nترتّب العيلة دي\nالخلاصة الـ light بيمشي waves شايلة energy\nحتى في الفضا\nالـ wavelength مسافة بين two crests والـ\nfrequency عدد الـ waves في الثانية\nفي الـ light الـ wavelength الأقصَر الـ\nfrequency بتاعه أعلى","countable":false,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":82,"see_also":[{"item_id":"chem-s3-en.lesson-te.uses-sc-ti","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Economic importance of scandium and titanium","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":42.19,"kind":"pause_question","spec":{"answer":"الـ light: بيمشي على شكل waves شايلة energy، حتى في الفضا الفاضي اللي مفيهوش هوا.","prompt":"إيه اللي بيوصّل الـ energy من الشمس لحد وشّك؟","options":[{"id":"a","text":"الـ light","correct":true},{"id":"b","text":"هوا سخن","correct":false},{"id":"c","text":"صوت","correct":false}],"answer_t_s":45.8,"concept_id":"phys.waves-light"},"content_lang":"ar-EG"},{"id":"think-2","t_s":98.42,"kind":"pause_question","spec":{"answer":"أعلى: الـ waves الأقصر بتعدّي منها crests أكتر في نفس الثانية.","prompt":"نفس السرعة، والـ waves بقت أقصر: الـ frequency هتعمل إيه؟","options":[{"id":"a","text":"هتبقى أعلى","correct":true},{"id":"b","text":"هتبقى أقل","correct":false},{"id":"c","text":"هتفضل زي ما هي، عشان السرعة واحدة","correct":false}],"answer_t_s":102.23,"concept_id":"phys.waves-light"},"content_lang":"ar-EG"},{"id":"think-3","t_s":183.49,"kind":"pause_question","spec":{"answer":"الـ blue light: الـ wavelength أقصر، يعني frequency أعلى.","prompt":"الـ red light الـ wavelength بتاعه أطول، والـ blue light أقصر: مين الـ frequency بتاعه أعلى؟","options":[{"id":"a","text":"الـ blue light","correct":true},{"id":"b","text":"الـ red light","correct":false},{"id":"c","text":"زي بعض، عشان نفس السرعة","correct":false}],"answer_t_s":188.05,"concept_id":"phys.waves-light"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-phys.waves-light"]},{"id":"chem-s3-en.video-walkthrough-phys.em-spectrum","kind":"walkthrough","version":5,"ord":78,"content_lang":"ar-EG","primary_concept_id":"phys.em-spectrum","concepts":[{"concept_id":"phys.em-spectrum","role":"primary"}],"title":"Electromagnetic radiation (UV, X-rays, gamma): from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-phys.em-spectrum (current v2, same written content as v1: s1 hook 'Burnt, but not hot' cloudy beach, options infrared / UV / bright visible light; s2 'A family of waves' KeyTerm 'Electromagnetic radiation: Waves that carry energy at the speed of light, even through empty space.', 'In empty space, all of them travel at the same speed', 'Shorter wavelength means higher frequency and more energy', figure order radio → gamma; s3 cards per ray (radio/TV signals, microwaves, infrared felt as heat, visible red→violet, UV burns skin, X-rays pass through skin less through bone, gamma shortest wavelength, highest energy, highest penetrating power); s4 table 'Invisible is not weak' + trap 'UV is invisible, so it must be weak'; s5 sort + hospital X-ray item + tf gamma particles; s6 recap, 'Next: which compound of titanium protects the skin from UV?'); en layer; concept phys.em-spectrum v2 + misconceptions mc1 'Gamma rays are particles' (refuted s2l18–s2l19) and mc2 'Only visible light is electromagnetic radiation' (refuted s2l6–s2l9); book Ch.1 p.5 (TiO2 nanoparticles prevent effect of UV on the skin), p.6 (cobalt 60 produces gamma rays which have high penetrating power), p.7 (ZnS … x-ray screens). Lesson verdicts read (yaanictl verify list, all runs): the failures were feedback wording (look-again nudges / guiding questions in s5 feedback), plus not-in-source notes 'UV still reaches you on a cloudy day' and 'X-rays pass through the body more easily than UV', and the absolute 'every member of that family'. This script repeats none of them: no claim that UV passes clouds (the anchor only says you still get sunburnt, the lesson hook), no X-ray vs UV penetration comparison, no 'passing through needs more energy', the self-check answer reasons only by place in the spectrum, no 'every member' absolute, infrared 'felt as warmth' without 'only'. Speed: 'the speed of light' only 'in empty space' (rule prereq-scoping); the full list includes microwaves. Dependents named in s4 (map title_en exactly): te.uses-sc-ti 'Economic importance of scandium and titanium' (UV, the titanium sunscreen question is the lesson's own 'Next'; compound not named), phys.radioactivity-gamma 'Radioactivity and gamma rays' (penetrating power), te.uses-cu-zn 'Economic importance of copper and zinc' (X-ray screens; compound not named). Terms (defined at first use): s1 wave, wavelength, energy (3); s2 visible light, electromagnetic radiation, radio waves, microwaves, infrared, ultraviolet (UV), X-rays, gamma rays, electromagnetic spectrum, frequency, particles (in the myth), penetrating power; s3 none new; s4 none new beyond the dependent titles. The definition card is split over s2l4–s2l5 so every term shown is spoken in its line. Worked example: microwaves (2) vs ultraviolet (5) — place in the spectrum → shorter wavelength → more energy. Self-check (new case, different pair): the hospital bone image uses X-rays; more or less energy than UV? → more: X-rays come after UV, shorter wavelength. Predicts: s2l13 (3.0 s), s3l8 (4.0 s). not-in-source: s2l20 gloss of penetrating power 'how easily a ray passes through things'; s1l7 waves' energy 'can heat or harm' (generic gloss). Estimate: 47 lines, ~545 words at ~2.4 words/s ≈ 228 s + 37 s pauses ≈ 265 s (≈ 4.4 min); recap s4l6–s4l8 ≈ 17 s.","title":"Electromagnetic radiation (UV, X-rays, gamma): from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Everyday anchor (lesson hook 'Burnt, but not hot'): YK.camera push-in (1.0 s) on the beach; a thermometer YK.thermo(ctx, 1600, 820, 260, {level: 0.3, col: C.cyan}) stays low on cue 'حر'. Clouds drift (≤ 2 %). Text panel: YK.fpara 'A cloudy beach day: you don't feel hot' (44).","tts_text":"تخيّل يوم على البحر والسما مغيّمة، ومش حاسس بأي حر.","screen_text":"A cloudy beach day: you don't feel hot","pause_after_s":0.4},{"id":"s1l3","visual":"A forearm silhouette (YK.bodyShape-style page-local arm path, soft grey) on the sand; its skin tint tweens to a sunburn pink (YK.mix C.textDim → C.coral at 40 %) on cue 'احمرّ'; a gold '?' (YK.tag) pops on 'إزاي'. Text panel: YK.fpara 'Still sunburnt. How?' (48).","tts_text":"وفي آخر اليوم، تلاقي جلدك احمرّ واتحرق برضه. إزاي؟","screen_text":"Still sunburnt. How?","pause_after_s":0.6},{"id":"s1l4","visual":"Analogy then real model (G3): the sea's surface line rises into one clean side-view wave drawn with YK.wave(ctx, 820, 560, 1800, 560, {t, amp: 60, wl: 300, color: C.gold, speed: 0.6}) coming from the Sun disc on cue 'wave'. Text panel: YK.termCard(ctx, 96, 420, {term: 'wave', align: 'left', p: from cue 'wave'}).","tts_text":"الشمس بتبعت ضوء، والضوء بيمشي على شكل wave، يعني موجة زي موج البحر.","screen_text":"wave","pause_after_s":0.4},{"id":"s1l5","visual":"The wave freezes; two neighbouring tops get gold dots on cues 'قمة' / 'للقمة' and a double-headed arrow (page-local, drawn left → right) spans them, YK.tag 'wavelength' on cue 'wavelength' (number: 1 wave). Text panel: YK.termCard(ctx, 96, 560, {term: 'wavelength', align: 'left', p: from cue 'wavelength'}) + YK.fpara 'the length of one wave, top to top' (40).","tts_text":"طول الموجة الواحدة، من قمة للقمة اللي بعدها، اسمه wavelength كده.","screen_text":"wavelength: the length of one wave, top to top","pause_after_s":0.4},{"id":"s1l6","visual":"Two YK.wave rows: top long (wl 360, C.cyan) labelled YK.tag 'long wavelength' on cue 'طويل', bottom short (wl 120, C.violet) labelled 'short wavelength' on cue 'قصير'; both move at the same px/s (speed = constant / wl).","tts_text":"فيه waves الـ wavelength بتاعها طويل، وفيه waves الـ wavelength بتاعها قصير.","screen_text":"waves: long wavelength · short wavelength","pause_after_s":0.4},{"id":"s1l7","visual":"A gold glow (YK.glowCircle, alpha 0.5) rides each wave row on cue 'energy'; at the right end the long-wave row warms a small pot icon (YK.icon 'pot', C.molten tint) on cue 'تسخّن' and the short-wave row hits the sunburnt arm tint on 'تأذي'. Text panel: YK.termCard(ctx, 96, 420, {term: 'energy', align: 'left', p: from cue 'energy'}) + YK.fpara 'waves carry energy' (40).","tts_text":"والـ waves دي شايلة energy، يعني طاقة، تقدر تسخّن أو تأذي.","screen_text":"energy · waves carry energy","pause_after_s":0.4},{"id":"s1l8","visual":"Micro-recap: the three term cards collapse into YK.chip(ctx, 96, y, label, {kind: 'concept', align: 'left'}) at y 300 / 400 / 500 ('wave', 'wavelength', 'energy'); stage: the sunburnt arm with the gold '?' returns beside the two wave rows. Text panel line 'Which waves burned the skin?' (44) on cue 'waves'.","tts_text":"طب أنهي waves فيهم هي اللي حرقت الجلد بالظبط؟","screen_text":"Which waves burned the skin?","pause_after_s":1},{"id":"s2l2","visual":"Stage: an eye icon (page-local outline, C.text) on the left; a rainbow band (page-local linear gradient red → violet, the real colours of visible light) appears in front of it on cue 'visible' (number: 1). Text panel: YK.termCard(ctx, 96, 420, {term: 'visible light', def: 'the part our eyes can see', align: 'left', p: from cue 'visible'}).","tts_text":"عينينا بتشوف نوع واحد من الـ waves دي، اسمه visible light كده.","screen_text":"visible light: the part our eyes can see","pause_after_s":0.4},{"id":"s2l3","visual":"Camera pulls back (YK.camera 1.2 s inOut): the rainbow band becomes ONE slot in the middle of a long dark strip of 7 rounded slots (page-local, textDim outlines; the other 6 slots empty and unlabelled for now) on cue 'عيلة' (number: 1 member).","tts_text":"والـ visible light ده واحد من عيلة waves كبيرة.","screen_text":"visible light: one member of a family of waves","pause_after_s":0.4},{"id":"s2l4","visual":"Definition card (lesson step s2 KeyTerm, first clause and last clause; the speed clause comes in s2l5): YK.termCard(ctx, 96, 340, {term: 'Electromagnetic radiation', def: 'Waves that carry energy, even through empty space.', keys: ['carry energy'], align: 'left', p: from cue 'electromagnetic'}); the 7-slot strip gets a header YK.tag 'Electromagnetic radiation' (40) on the same cue; a gold YK.wave crosses an empty dark gap (Sun → Earth) under the strip on 'الفضا'.","tts_text":"اسمها الـ electromagnetic radiation، ودي waves شايلة energy، حتى في الفضا الفاضي.","screen_text":"Electromagnetic radiation: waves that carry energy, even through empty space","pause_after_s":0.4},{"id":"s2l5","visual":"Seven small wave fronts (gold markers) leave the left edge of the strip together and stay lined up as they move right on cue 'بسرعة' (same px/s; number: 7 rays). YK.fpara 'In empty space: all travel at the speed of light' (40) under the definition card, 'In empty space' in gold (rule: equal speed only in empty space).","tts_text":"وفي الفضا الفاضي، كلهم بيمشوا بسرعة الـ light نفسها.","screen_text":"In empty space: all travel at the speed of light","pause_after_s":0.4},{"id":"s2l6","visual":"Misconception phys.em-spectrum.mc2: YK.mythLine(ctx, t, {at: YK.cue('s2l6'), wrongAt: YK.cueX('s2l6','غلط'), until: YK.cueEnd('s2l8') + 1.5, text: 'Only visible light is electromagnetic radiation?', x: 96, y: 300, size: 44}) coral with ✕ for its whole visible time; on the strip the visible slot glows while the six empty slots flash coral once on 'غلط'. No strike-through.","tts_text":"ناس فاكرة إن الـ visible light بس هو الـ electromagnetic radiation؛ غلط.","screen_text":"Only visible light is electromagnetic radiation? ✕","pause_after_s":0.4},{"id":"s2l7","visual":"Fix (held ≥ the myth, slots fill left → right, G18): slot 1 fills with a long YK.wave (wl 220) + YK.tag 'radio waves' and YK.icon 'tower' on cue 'radio'; slot 2 'microwaves' (wl 150) + YK.icon 'microwave' on cue 'microwaves'; slot 3 'infrared' (wl 110) + a faint heat shimmer on cue 'infrared'. YK.rightMark next to the strip on the first fill.","tts_text":"أول العيلة الـ radio waves، وبعدها الـ microwaves، وبعدها الـ infrared كده.","screen_text":"radio waves → microwaves → infrared ✓","pause_after_s":0.3},{"id":"s2l8","visual":"Slot 4 (the rainbow, already there) pulses on cue 'visible'; slot 5 fills with a shorter YK.wave (wl 70, violet) + YK.tag 'ultraviolet (UV)' on cue 'ultraviolet', the '(UV)' part lighting on cue 'UV'.","tts_text":"وبعدهم الـ visible light، وبعده الـ ultraviolet، واسمه المختصر UV كده.","screen_text":"→ visible light → ultraviolet (UV)","pause_after_s":0.3},{"id":"s2l9","visual":"Slot 6 'X-rays' (wl 45) + YK.icon 'bone' on cue 'X-rays'; slot 7 'gamma rays' (wl 28) + YK.icon 'gamma' on cue 'gamma'. The full strip now reads, left → right: radio waves, microwaves, infrared, visible light, ultraviolet (UV), X-rays, gamma rays (the lesson's order; numbers 1–7 under the slots, textDim 32).","tts_text":"وبعده الـ X-rays، وبعدها الـ gamma rays، آخر العيلة.","screen_text":"→ X-rays → gamma rays","pause_after_s":0.6},{"id":"s2l10","visual":"A gold YK.bracket(ctx, stripX - 12, stripY - 12, stripW + 24, stripH + 24, prog from cue 'electromagnetic') draws left → right around the whole strip; YK.termCard(ctx, 96, 420, {term: 'electromagnetic spectrum', align: 'left', p: from cue 'spectrum'}).","tts_text":"والترتيب ده اسمه الـ electromagnetic spectrum، يعني طيف.","screen_text":"electromagnetic spectrum","pause_after_s":0.4},{"id":"s2l11","visual":"Two gold arrows (page-drawn) run along the strip left → right: under it 'shorter wavelength' on cue 'بتقصر', above it 'more energy' on cue 'بتزيد' (lesson figure labels); the slots' waves visibly shorten left → right. Text panel: YK.fpara (44) same line.","tts_text":"ومن الـ radio waves لحد الـ gamma rays، الـ wavelength بتقصَر والـ energy بتزيد.","screen_text":"radio waves → gamma rays: shorter wavelength, more energy","pause_after_s":0.4},{"id":"s2l12","visual":"A third arrow label 'higher frequency' joins the 'shorter wavelength' arrow on cue 'frequency'; a gate line (page-local) on slots 1 and 7 counts crests: the slot-7 counter ticks faster during a 1-second ring (YK.label, page-computed) on 'الثانية'.","tts_text":"ومع الـ wavelength الأقصَر، الـ frequency بتزيد، يعني waves أكتر في الثانية.","screen_text":"shorter wavelength → higher frequency","pause_after_s":0.6},{"id":"s2l13","visual":"Back to the anchor: the sunburnt arm returns small at the stage left. YK.predictCard(ctx, t, {at: YK.cue('s2l13'), until: YK.cue('s2l14') + 0.4, think: YK.cueEnd('s2l13'), end: YK.cue('s2l14'), kind: 'PREDICT', q: 'What burns the skin: infrared, visible light or UV?'}); the three slots light on their cues. Only the question shows through the think ring.","tts_text":"إيه اللي حرق الجلد: الـ infrared، ولا الـ visible light، ولا الـ UV؟ فكّر.","screen_text":"PREDICT: What burns the skin? infrared · visible light · UV","pause_after_s":3},{"id":"s2l14","visual":"Answer: the UV slot gets YK.rightMark and a gold outline on cue 'UV'; a violet dashed YK.wave (invisible rays drawn dashed + textDim tag 'invisible') passes through the clouds of the anchor and reaches the arm on 'energy'. YK.answerSlot(ctx, t, {at: YK.cueX('s2l14','UV'), text: 'UV: more energy than visible light', x: 300, y: 600}).","tts_text":"الـ UV: الـ energy بتاعته أعلى من الـ visible light، مع إننا مش بنشوفه.","screen_text":"UV ✓ invisible, but more energy than visible light","pause_after_s":0.4},{"id":"s2l15","visual":"Lesson misconception (step s4 trap 'UV is invisible, so it must be weak'): YK.mythLine(ctx, t, {at: YK.cue('s2l15'), wrongAt: YK.cueX('s2l15','غلط'), until: YK.cueEnd('s2l16') + 1.5, text: 'Invisible means weak?', x: 96, y: 300, size: 48}) coral with ✕ for its whole visible time.","tts_text":"ناس فاكرة إن اللي مش بنشوفه يبقى ضعيف؛ وده غلط.","screen_text":"Invisible means weak? ✕","pause_after_s":0.4},{"id":"s2l16","visual":"Fix held ≥ the myth: the eye icon with a bracket only over the visible slot on cue 'عينينا'; then the UV slot's short wave pulses next to the visible slot's longer wave on 'أقصر' and the 'more energy' arrow glows on 'أعلى'. YK.answerSlot(ctx, t, {at: YK.cueX('s2l16','عينينا'), text: 'Seeing depends on our eyes, not on energy', x: 300, y: 560}) (lesson correction wording).","tts_text":"الشوف بيعتمد على عينينا، والـ UV الـ wavelength بتاعه أقصَر، فالـ energy أعلى.","screen_text":"Seeing depends on our eyes · UV: shorter wavelength → more energy ✓","pause_after_s":0.4},{"id":"s2l17","visual":"Contrast (lesson table 'Invisible is not weak'): the infrared slot (left of visible) glows warm and a hot stove icon (YK.icon 'pot' over page-local burner) gives a faint heat shimmer on cue 'دفا'; a small down arrow 'less energy' on cue 'أقل'. YK.fpara (40) in the text panel.","tts_text":"والـ infrared كمان مش بنشوفه، إنما الـ energy بتاعته أقل، وبنحِسّ بيه دِفا.","screen_text":"infrared: invisible too, less energy: we feel it as warmth","pause_after_s":0.6},{"id":"s2l18","visual":"Misconception phys.em-spectrum.mc1: YK.mythLine(ctx, t, {at: YK.cue('s2l18'), wrongAt: YK.cueX('s2l18','غلط'), until: YK.cueEnd('s2l19') + 1.5, text: 'Gamma rays are tiny particles?', x: 96, y: 300, size: 48}) with ✕; on the stage, coral dots (YK.dot) fly out of the gamma slot, marked YK.wrongMark for their whole visible time.","tts_text":"وناس فاكرة إن الـ gamma rays دي particles صغيرة؛ غلط برضه.","screen_text":"Gamma rays are tiny particles? ✕","pause_after_s":0.4},{"id":"s2l19","visual":"Fix: the coral dots fade and the gamma slot shows its very short YK.wave again (wl 28, gold glow) on cue 'waves'; a gold link line runs from the gamma slot to the visible slot on 'light'. YK.answerSlot(ctx, t, {at: YK.cueX('s2l19','waves'), text: 'Gamma rays: waves like light', x: 300, y: 560}).","tts_text":"الـ gamma rays دي waves زي الـ light، من نفس العيلة دي.","screen_text":"Gamma rays: waves like light, same family ✓","pause_after_s":0.6},{"id":"s2l20","visual":"New picture: a block of material (page-local grey slab) in front of the strip; YK.termCard(ctx, 96, 420, {term: 'penetrating power', def: 'how easily a ray passes through things', align: 'left', p: from cue 'penetrating'}); a ray arrow (page-local) enters the slab on cue 'تعدّي'.","tts_text":"والـ penetrating power يعني قدّ إيه الأشعة تعدّي جوه الحاجات.","screen_text":"penetrating power: how easily a ray passes through things","pause_after_s":0.4},{"id":"s2l21","visual":"Lesson card 'X-rays': a hand outline (page-local) with bones inside; X-ray waves (slot 6 colour) pass through the skin area on cue 'الجلد' and are mostly stopped by the bones on 'العضم'#1, leaving a bone shadow image (YK.icon 'bone' tint) on a screen behind on 'صورة'.","tts_text":"الـ X-rays بتعدّي من الجلد، وأقل من العضم، فبتطلع صورة العضم.","screen_text":"X-rays: pass through skin, less through bone","pause_after_s":0.4},{"id":"s2l22","visual":"The gamma slot glows gold (focus); a gamma ray (YK.wave wl 28, gold) passes through the slab of s2l20 and comes out the far side on cue 'penetrating' (lesson recap 'the highest energy and the highest penetrating power'; book p.6 cobalt-60 gamma rays 'high penetrating power'). No side-by-side penetration race with UV or X-rays (not in the sources). The 'more energy' arrow tip lights on 'energy'.","tts_text":"والـ gamma rays فيها أعلى energy، وأعلى penetrating power كمان.","screen_text":"Gamma rays: the highest energy and the highest penetrating power","pause_after_s":1},{"id":"s3l2","visual":"Stage: the 7-slot strip of s2 (small, y 300); the microwaves and ultraviolet slots get gold outlines on their cues. Text panel: YK.list header 'Which has more energy: microwaves or ultraviolet?'.","tts_text":"سؤال: الـ microwaves ولا الـ ultraviolet، مين الـ energy بتاعه أعلى؟","screen_text":"Which has more energy: microwaves or ultraviolet?","pause_after_s":0.4},{"id":"s3l3","visual":"A gold cursor (YK.marker sweep, left → right) runs along the strip from slot 1 on cue 'radio'. YK.list item 1 'Step 1: find both in the spectrum, from radio waves'.","tts_text":"أول خطوة: ندوّر عليهم في الـ spectrum من الـ radio waves للآخر.","screen_text":"Step 1: find both in the spectrum, from radio waves","pause_after_s":0.4},{"id":"s3l4","visual":"Step 2: the cursor stops at slot 2 (YK.tag '2', gold) on cue 'two' and at slot 5 (YK.tag '5') on cue 'five'; the gamma end of the strip glows faintly on 'gamma' (numbers: 2, 5, 7). YK.list item 2.","tts_text":"الـ microwaves رقم two، والـ ultraviolet رقم five، ناحية الـ gamma rays أكتر.","screen_text":"microwaves: 2 · ultraviolet: 5 (of 7)","pause_after_s":0.4},{"id":"s3l5","visual":"Step 3: the 'shorter wavelength' arrow under the strip relights; the waves in slots 2 and 5 are enlarged side by side (YK.wave wl 150 vs wl 70) on cue 'wavelength'. YK.list item 3.","tts_text":"وإحنا ماشيين ناحية الـ gamma rays، الـ wavelength بتقصَر.","screen_text":"Step 3: toward gamma rays, the wavelength gets shorter","pause_after_s":0.4},{"id":"s3l6","visual":"Step 4: the ultraviolet wave glows gold, YK.rightMark on cue 'أعلى'; the microwaves wave dims to 35%. YK.list item 4 'ultraviolet: shorter wavelength → more energy'.","tts_text":"يبقى الـ ultraviolet الـ wavelength بتاعه أقصَر، والـ energy بتاعته أعلى.","screen_text":"ultraviolet: shorter wavelength → more energy ✓","pause_after_s":0.8},{"id":"s3l7","visual":"Self-check on a NEW case (lesson check s5 situation, different pair from the example): stage clears to an X-ray image of a hand (page-local, bones bright on dark) on cue 'صورة'; YK.tag 'X-rays' (40) on cue 'X-rays'. The strip stays visible small at the top, nothing highlighted.","tts_text":"دورك: صورة العضم في المستشفى، الأشعة بتاعتها اسمها X-rays كده.","screen_text":"Your turn: a hospital image of bones uses X-rays","pause_after_s":0.4},{"id":"s3l8","visual":"YK.predictCard(ctx, t, {at: YK.cue('s3l8'), until: YK.cue('s3l9') + 0.4, think: YK.cueEnd('s3l8'), end: YK.cue('s3l9'), kind: 'QUICK CHECK', q: 'X-rays compared with UV: more or less energy?'}); YK.checkPause(ctx, 1307, 880, {t, start: YK.cueEnd('s3l8'), dur: 4}); only the question shows during the pause (no highlight on the strip).","tts_text":"الـ X-rays دي الـ energy بتاعتها أعلى ولا أقل من الـ UV؟ وقّف وفكّر.","screen_text":"Compared with UV: more or less energy?","pause_after_s":4},{"id":"s3l9","visual":"Answer: on the strip the UV slot (5) and the X-rays slot (6) light in turn on cues 'UV' / 'X-rays'; the 'shorter wavelength' and 'more energy' arrows relight; YK.answerSlot(ctx, t, {at: YK.cueX('s3l9','الإجابة'), text: 'More energy: X-rays come after UV', x: 300, y: 600}) (numbers on screen: 5, 6). The reason is the place in the spectrum (no claim about why rays pass through the body).","tts_text":"الإجابة: energy أعلى؛ الـ X-rays جاية بعد الـ UV، والـ wavelength أقصَر.","screen_text":"More energy ✓ X-rays come after UV: shorter wavelength","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, 'Economic importance of scandium and titanium', {kind: 'concept', align: 'left'}) (map title_en exactly; book Ch.1 p.5) on cue 'economic'; YK.tag 'UV' (40, violet) beside it on cue 'UV'.","tts_text":"في الـ economic importance بتاعة الـ scandium والـ titanium، هتقابل الـ UV كمان.","screen_text":"Economic importance of scandium and titanium · UV","pause_after_s":0.4},{"id":"s4l3","visual":"YK.icon(ctx, 'sunscreen', 1500, 260, 120, C.cyan) next to the chip on cue 'بتحمي' with a '?' tag (the lesson's own 'Next' question; the compound is named in the chapter, not here).","tts_text":"هتعرف أنهي مادة فيها titanium بتحمي الجلد من الـ UV بتاع الشمس.","screen_text":"Titanium and UV protection for the skin: in the chapter","pause_after_s":0.4},{"id":"s4l4","visual":"Second YK.chip(ctx, 820, 460, 'Radioactivity and gamma rays', {kind: 'concept', align: 'left'}) on cue 'radioactivity'; YK.icon 'gamma' + YK.tag 'penetrating power' (40) on cue 'penetrating' (book p.6 names gamma rays' high penetrating power; its uses stay for the chapter).","tts_text":"وفي الـ radioactivity، هتقابل الـ gamma rays والـ penetrating power بتاعتها.","screen_text":"Radioactivity and gamma rays · penetrating power","pause_after_s":0.4},{"id":"s4l5","visual":"Third YK.chip(ctx, 820, 700, 'Economic importance of copper and zinc', {kind: 'concept', align: 'left'}) on cue 'economic'; a small screen outline (page-local) with YK.tag 'X-ray screens' on cue 'X-ray' (book p.7 'x-ray screens'; the compound used is left to the chapter).","tts_text":"وفي الـ economic importance بتاعة الـ copper والـ zinc، هتقابل شاشات الـ X-ray كمان.","screen_text":"Economic importance of copper and zinc · X-ray screens","pause_after_s":0.6},{"id":"s4l6","visual":"Recap (s4l6–s4l8 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l6'), until: YK.cue('s4l8'), title: 'Electromagnetic radiation', line: 'visible light: one member of electromagnetic radiation', pulse: [{word: 'visible', at: YK.cueX('s4l6','visible')}]}); stage: the full 7-slot strip with the visible slot glowing (number: 1).","tts_text":"الخلاصة: الـ visible light واحد من عيلة الـ electromagnetic radiation الكبيرة.","screen_text":"visible light: one member of electromagnetic radiation","pause_after_s":0.4},{"id":"s4l7","visual":"Same recap card, second line on cue 'UV' (lesson recap 'UV has more energy than visible light, so it can damage the skin'); the UV slot and the anchor's sunburnt arm light together on 'الجلد'.","tts_text":"والـ UV الـ energy بتاعته أعلى من الـ visible light، فممكن يأذي الجلد.","screen_text":"UV: more energy than visible light, so it can damage the skin","pause_after_s":0.6},{"id":"s4l8","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Remember', line: 'From radio waves to gamma rays: shorter wavelength, more energy.', t, pulse: [{word: 'shorter', at: YK.cueX('s4l8','بتقصر')}, {word: 'energy', at: YK.cueX('s4l8','energy')}]}); the strip's two arrows glow under the card; holds to the end (no fade to black).","tts_text":"من الـ radio waves لحد الـ gamma rays، الـ wavelength بتقصَر والـ energy بتزيد.","screen_text":"From radio waves to gamma rays: shorter wavelength, more energy.","pause_after_s":1.5}],"logline":"هتعرفوا عيلة الـ electromagnetic radiation بالترتيب، وليه الـ UV ممكن يحرق الجلد مع إننا مش بنشوفه.","segments":[{"id":"s1","title":"A cloudy beach day and a sunburn","concept_id":"phys.em-spectrum"},{"id":"s2","title":"The electromagnetic spectrum","concept_id":"phys.em-spectrum"},{"id":"s3","title":"Microwaves or ultraviolet: which has more energy?","concept_id":"phys.em-spectrum"},{"id":"s4","title":"Where Chapter 1 uses electromagnetic 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يوم على البحر والسما مغيّمة ومش حاسس\nبأي حر\nوفي آخر اليوم تلاقي جلدك احمر واتحرق برضه\nإزاي\nالشمس بتبعت ضوء والضوء بيمشي على شكل wave\nيعني موجة زي موج البحر\nطول الموجة الواحدة من قمة للقمة اللي بعدها\nاسمه wavelength كده\nفيه waves الـ wavelength بتاعها طويل وفيه\nwaves الـ wavelength بتاعها قصير\nوالـ waves دي شايلة energy يعني طاقة تقدر\nتسخّن أو تأذي\nطب أنهي waves فيهم هي اللي حرقت الجلد\nبالظبط\nعينينا بتشوف نوع واحد من الـ waves دي اسمه\nvisible light كده\nوالـ visible light ده واحد من عيلة waves\nكبيرة\nاسمها الـ electromagnetic radiation ودي\nwaves شايلة energy حتى في الفضا الفاضي\nوفي الفضا الفاضي كلهم بيمشوا بسرعة الـ\nlight نفسها\nناس فاكرة إن الـ visible light بس هو الـ\nelectromagnetic radiation غلط\nأول العيلة الـ radio waves وبعدها الـ\nmicrowaves وبعدها الـ infrared كده\nوبعدهم الـ visible light وبعده الـ\nultraviolet واسمه المختصر UV كده\nوبعده الـ X-rays وبعدها الـ gamma rays آخر\nالعيلة\nوالترتيب ده اسمه الـ electromagnetic\nspectrum يعني طيف\nومن الـ radio waves لحد الـ gamma rays الـ\nwavelength بتقصَر والـ energy بتزيد\nومع الـ wavelength الأقصَر الـ frequency\nبتزيد يعني waves أكتر في الثانية\nإيه اللي حرق الجلد الـ infrared ولا الـ\nvisible light ولا الـ UV فكّر\nالـ UV الـ energy بتاعته أعلى من الـ\nvisible light مع إننا مش بنشوفه\nناس فاكرة إن اللي مش بنشوفه يبقى ضعيف وده\nغلط\nالشوف بيعتمد على عينينا والـ UV الـ\nwavelength بتاعه أقصَر فالـ energy أعلى\nوالـ infrared كمان مش بنشوفه إنما الـ\nenergy بتاعته أقل وبنحِس بيه دِفا\nوناس فاكرة إن الـ gamma rays دي particles\nصغيرة غلط برضه\nالـ gamma rays دي waves زي الـ light من\nنفس العيلة دي\nوالـ penetrating power يعني قد إيه الأشعة\nتعدّي جوه الحاجات\nالـ X-rays بتعدّي من الجلد وأقل من العضم\nفبتطلع صورة العضم\nوالـ gamma rays فيها أعلى energy وأعلى\npenetrating power كمان\nسؤال الـ microwaves ولا الـ ultraviolet\nمين الـ energy بتاعه أعلى\nأول خطوة ندوّر عليهم في الـ spectrum من\nالـ radio waves للآخر\nالـ microwaves رقم two والـ ultraviolet\nرقم five ناحية الـ gamma rays أكتر\nوإحنا ماشيين ناحية الـ gamma rays الـ\nwavelength بتقصَر\nيبقى الـ ultraviolet الـ wavelength بتاعه\nأقصَر والـ energy بتاعته أعلى\nدورك صورة العضم في المستشفى الأشعة بتاعتها\nاسمها X-rays كده\nالـ X-rays دي الـ energy بتاعتها أعلى ولا\nأقل من الـ UV وقّف وفكّر\nالإجابة energy أعلى الـ X-rays جاية بعد\nالـ UV والـ wavelength أقصَر\nطب الكلام ده هيفيدك فين في الفصل\nفي الـ economic importance بتاعة الـ\nscandium والـ titanium هتقابل الـ UV كمان\nهتعرف أنهي مادة فيها titanium بتحمي الجلد\nمن الـ UV بتاع الشمس\nوفي الـ radioactivity هتقابل الـ gamma\nrays والـ penetrating power بتاعتها\nوفي الـ economic importance بتاعة الـ\ncopper والـ zinc هتقابل شاشات الـ X-ray\nكمان\nالخلاصة الـ visible light واحد من عيلة الـ\nelectromagnetic radiation الكبيرة\nوالـ UV الـ energy بتاعته أعلى من الـ\nvisible light فممكن يأذي الجلد\nمن الـ radio waves لحد الـ gamma rays الـ\nwavelength بتقصَر والـ energy بتزيد","countable":false,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":83,"see_also":[{"item_id":"chem-s3-en.lesson-te.uses-sc-ti","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Economic importance of scandium and titanium","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":103.34,"kind":"pause_question","spec":{"answer":"الـ UV: مش بنشوفه، بس الـ energy بتاعته أعلى من الـ visible light.","prompt":"في يوم غايم، إيه اللي حرق الجلد: الـ infrared ولا الـ visible light ولا الـ UV؟","options":[{"id":"a","text":"الـ UV","correct":true},{"id":"b","text":"الـ infrared","correct":false},{"id":"c","text":"الـ visible light","correct":false}],"answer_t_s":106.82,"concept_id":"phys.em-spectrum"},"content_lang":"ar-EG"},{"id":"think-2","t_s":195.32,"kind":"pause_question","spec":{"answer":"أعلى: الـ X-rays جاية بعد الـ UV في الـ spectrum، والـ wavelength أقصر.","prompt":"الـ X-rays مقارنة بالـ UV: الـ energy أعلى ولا أقل؟","options":[{"id":"a","text":"أعلى","correct":true},{"id":"b","text":"أقل","correct":false}],"answer_t_s":199.58,"concept_id":"phys.em-spectrum"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-phys.em-spectrum"]},{"id":"chem-s3-en.video-walkthrough-chem.acids-bases-salts","kind":"walkthrough","version":6,"ord":90,"content_lang":"ar-EG","primary_concept_id":"chem.acids-bases-salts","concepts":[{"concept_id":"chem.acids-bases-salts","role":"primary"}],"title":"Acids, bases and salts: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.acids-bases-salts (hook: NaCl and CuSO4 both salts, nobody eats CuSO4; KeyTerms Acid / Base / Alkali / Salt used verbatim on the definition cards; ion gloss 'an atom, or a group of atoms, with an electric charge'; acids sour, litmus red, never taste them in the lab; table HCl/H2SO4/HNO3 → chlorides/sulphates/nitrates; 'Many metal oxides and metal hydroxides are bases' (CuO, Mg(OH)2); alkalis NaOH, NH4OH turn litmus blue; TF misconception 'NaOH is an acid because its formula contains H' (refuted s2l18–s2l21 with the layer's reason: H is part of the OH group, gives OH- ions); hook misconception 'salts taste salty / are eaten' (refuted s2l25–s2l26); naming rule metal from the base + ending from the acid; equation NaOH + HCl -> NaCl + H2O (lesson step 5, the one written equation)). Concept chem.acids-bases-salts v2 has no recorded misconceptions: s2 refutes the lesson's two (above). Book: p.7 copper II sulphate used as insecticide (s2l26); acids scoped dilute per chem-s3-en.fact.acids-electrochem (s2l4, s3). Dependents named in s4 by map title (all chapter concepts): 'Acidic and basic oxides' (metal oxides as bases → salt + water, already said in s2l15/s2l10), 'Metal + dilute acid' (salt names chlorides/sulphates; its other product is left to that lesson to avoid acid.metal-acid-reaction.mc1), 'Types of chemical reactions' (acid + base is one type; the reaction's name is not given: no new term in s4). Terms at first use: s1 acid, salt, formula (+ element names sodium, chlorine, hydrogen glossed); s2 dilute, ion, atom, electric charge, litmus, base, oxide/hydroxide group (copper (II) oxide = copper + oxygen; '(II)' glossed as part of the name), metals, alkali, hydroxide ions, compound, chlorides, sulphates, nitrates. s3/s4 add none. Voicing: compound names with an Arabic numeral inside («copper اتنين oxide», «copper اتنين sulphate») per chem-s3-en.voice.groups-configs; formulas spoken by name; 'sulphuric/sulphate' spelling per edition. No line speaks a number while its screen shows a formula digit. Worked example: sodium hydroxide + dilute hydrochloric acid → sodium chloride (table salt, closes the s1 anchor) + water. Self-check (NEW case): magnesium hydroxide + dilute hydrochloric acid → magnesium chloride + water, pause 4 s, answer + reason. Predicts: s2l18 (~1:55), s3l10–11 (~4:30). not-in-source: atom = a tiny particle matter is built from (plain meaning); compound = atoms of more than one kind joined (plain meaning); hydrogen is a very light gas; NaCl = sodium + chlorine and table salt is sodium chloride; lemon and vinegar taste sour because they contain acids; in the worked example the water comes from the acid's hydrogen and the base's hydroxide (particle picture); Mg(OH)2 + dilute HCl → magnesium chloride + water; NaOH and HCl named 'dilute' in the example (lesson gives no strength; scoped per the brief's fact rule). Estimated duration ≈ 343 s (≈ 5:43; 670 words at ~2.4 words/s + 45 s pauses + joins); planning aid only.","title":"Acids, bases and salts: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"YK.camera pushes in on the lemon and the bottle (shaker dims to 35%); labels 'lemon' / 'vinegar' (YK.tag 40) pop under them on cues 'الليمون' / 'والخل'; a small YK.pulse ring around both on 'حامض'.","tts_text":"افتكر طعم الليمون والخل، طعمهم حامض، صح؟","screen_text":"lemon · vinegar","pause_after_s":0.6},{"id":"s1l3","visual":"YK.termCard(ctx, 96, 420, {term: 'acid', align: 'left', p: on cue 'acid'}) (no def yet: the lesson's definition comes in s2); amber YK.dot particles (YK.swarm, C.amber) glow inside the lemon and the bottle on the same cue.","tts_text":"الحموضة دي جاية من مادة جواهم اسمها acid، يعني حمض.","screen_text":"acid","pause_after_s":0.4},{"id":"s1l4","visual":"New picture: a lab glass (YK.beaker(ctx, 1300, 700, 300, 380, {level: 0.5, color: 'rgba(120,160,255,0.35)'})) slides in from the left on cue 'المعمل'; a tongue-and-spoon line drawing (page-local ctx path) beside it gets YK.wrongMark(ctx, 1600, 560, 110) on cue 'إوعى' and keeps it while visible; YK.fpara 'acid: never taste it in the lab' (44) in the text panel on cue 'acid'.","tts_text":"إنما في المعمل، إوعى تدوق أي acid، دي قاعدة مهمة.","screen_text":"acid: never taste it in the lab","pause_after_s":0.6},{"id":"s1l5","visual":"Beaker slides out; the salt shaker returns centre-stage and tips: white grains (seeded YK.dot, C.text) pour into a small dish on cue 'ملح'; YK.tag 'table salt' (44) under the dish on the same cue; YK.termCard(ctx, 96, 420, {term: 'salt', align: 'left'}) on cue 'salt'.","tts_text":"ودلوقتي ملح الأكل اللي على السفرة، اسمه في الكيميا salt برضه.","screen_text":"table salt","pause_after_s":0.4},{"id":"s1l6","visual":"Family picture: the dish of table salt shrinks into the first of five rounded YK.panel tiles in a row (x 820–1800, y 560); the other four tiles hold plain crystal heaps (neutral greys, no colours, seeded facets) that pop in left → right on 'عيلة'; YK.bracket around all five on 'كبيرة'; the table-salt tile pulses (YK.pulseA) on 'واحد'. No names on the other tiles yet.","tts_text":"الـ salt في الكيميا عيلة كبيرة، وملح الأكل واحد من أفرادها.","screen_text":"salt: a big family · table salt is one of them","pause_after_s":0.4},{"id":"s1l7","visual":"YK.termCard(ctx, 96, 420, {term: 'formula', align: 'left'}) on cue 'formula'; on the stage the table-salt tile grows and YK.formula(ctx, 'NaCl', 1307, 520, {size: 120, align: 'center'}) writes in above it on 'برموز'.","tts_text":"وملح الأكل ليه formula، يعني اسمه مكتوب برموز قصيرة.","screen_text":"formula","pause_after_s":0.4},{"id":"s1l8","visual":"'Na' and 'Cl' in the NaCl formula split apart slightly; YK.tag 'sodium' under 'Na' on cue 'sodium'#1, YK.tag 'chlorine' under 'Cl' on cue 'chlorine'; YK.fpara 'sodium chloride' (56, gold) under the formula on cue 'sodium'#2. Two YK.atomDisc (el 'Na', el 'Cl', r 46) sit side by side under it on the same cues.","tts_text":"الرمز ده معناه sodium مع chlorine، وده اسمه sodium chloride كده.","screen_text":"NaCl: sodium chloride · Na = sodium · Cl = chlorine","pause_after_s":0.4},{"id":"s1l9","visual":"New element card: YK.atomDisc(ctx, 1307, 560, 70, {el: 'H'}) pops in on cue 'hydrogen' with YK.tag 'H: hydrogen' (48) beside it; a few small H discs float upward (YK.particles mode 'up', seed 4, alpha 0.4) on 'خفيف' (light gas).","tts_text":"وهنقابل رمز تاني كتير: الـ hydrogen، وده غاز خفيف جدًا.","screen_text":"H: hydrogen","pause_after_s":0.4},{"id":"s1l10","visual":"Micro-recap: three YK.chip kind 'concept' in a row in the text panel (96, 300 / 420 / 540) on cues 'acid', 'salt', 'formula'; stage thumbnails (lemon, salt dish, NaCl formula) flash (YK.flashRect) in the same order.","tts_text":"يبقى معانا تلات كلمات: acid و salt و formula، خلّيهم في بالك.","screen_text":"acid · salt · formula","pause_after_s":1},{"id":"s2l2","visual":"Stage: two YK.beaker (x 1050 / 1350, y 720, 260×360, level 0.6, color 'rgba(120,160,255,0.35)') slide in from the left on cue 'المعمل'; labels under them 'hydrochloric acid' / 'sulphuric acid' (YK.tag 36) on their cues.","tts_text":"في المعمل فيه acids أشهرها الـ hydrochloric acid والـ sulphuric acid كمان.","screen_text":"hydrochloric acid · sulphuric acid","pause_after_s":0.4},{"id":"s2l3","visual":"Third YK.beaker (x 1650) labelled 'nitric acid' on cue 'nitric'; formulas above the three glasses (YK.formula mono 56: 'HCl', 'H2SO4', 'HNO3') on cue 'formula'; the H in each formula turns gold and pulses (YK.pulseA) on cue 'hydrogen'.","tts_text":"والـ nitric acid، وكل واحد منهم فيه hydrogen في الـ formula بتاعته.","screen_text":"nitric acid · HCl · H₂SO₄ · HNO₃: each has hydrogen","pause_after_s":0.4},{"id":"s2l4","visual":"One beaker centre-stage (level 0.25); water droplets pour in from a second glass (YK.flyer, C.cyan) and the level rises 0.25 → 0.7 on cue 'متخفف'. YK.termCard(ctx, 96, 420, {term: 'dilute', align: 'left'}) on cue 'dilute' + YK.fpara 'acid + a lot of water' (40) under it.","tts_text":"والـ acid بنستخدمه dilute، يعني متخفف بمَيّة كتير.","screen_text":"dilute: acid + a lot of water","pause_after_s":0.4},{"id":"s2l5","visual":"Zoom into the dilute beaker (YK.zoomThrough with YK.scaleBadge): inside the water, small discs drift apart from each other on cue 'يدوب'; one is ringed (YK.bracket, round) on cue 'المية،'; YK.termCard(ctx, 96, 420, {term: 'المية،', align: 'left'}) on the same cue.","tts_text":"لما الـ acid يدوب في المية، بيطلّع ions جوه المية.","screen_text":"ion","pause_after_s":0.4},{"id":"s2l6","visual":"Inset (YK.panel 1180, 200, 560, 360): a block of matter zooms down to a grid of identical YK.atomDisc (el 'H', r 30) on cue 'atom'; YK.tag 'atom' on one disc; YK.fpara 'atom: a tiny particle of matter' (40) in the text panel.","tts_text":"والـ atom ده حتة صغيرة جدًا بتتبني منها المواد.","screen_text":"atom: a tiny particle of matter","pause_after_s":0.4},{"id":"s2l7","visual":"Definition card (lesson wording): YK.termCard(ctx, 96, 380, {term: 'ion', def: 'An atom, or a group of atoms, with an electric charge.', keys: ['electric charge'], align: 'left'}); stage: one YK.atomDisc on cue 'atom'#1, then a group of three discs on 'مجموعة', each getting a small charge badge (YK.atomDisc o.charge '+' / '-') on cue 'electric'.","tts_text":"الـ ion ده atom، أو مجموعة atoms، عليه electric charge، يعني شُحنة.","screen_text":"ion: An atom, or a group of atoms, with an electric charge.","pause_after_s":0.6},{"id":"s2l8","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 380, {term: 'acid', def: 'A substance that gives positive hydrogen ions (H^+) when dissolved in water.', keys: ['hydrogen ions'], align: 'left'}); stage: in the zoomed water, YK.atomDisc el 'H' with charge '+' badges (r 34) spread out from an HCl particle on cue 'hydrogen'; label 'H^+' (YK.formula 48) on cue 'موجبة'.","tts_text":"يبقى الـ acid مادة بتدّي hydrogen ions موجبة لما تدوب في المية.","screen_text":"acid: A substance that gives positive hydrogen ions (H⁺) when dissolved in water.","pause_after_s":0.8},{"id":"s2l9","visual":"New picture: a paper strip (page-local ctx rect, neutral paper colour) dips into the acid beaker on cue 'ورقة'; its lower half tweens to red (YK.mix to C.coral) on cue 'الأحمر'; YK.tag 'litmus' (44) on cue 'litmus'; YK.fpara 'litmus: acid turns it red' (40) in the text panel.","tts_text":"وكمان الـ acid بيقلب ورقة الـ litmus للون الأحمر.","screen_text":"litmus: acid turns it red","pause_after_s":0.4},{"id":"s2l10","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 380, {term: 'base', def: 'A substance that reacts with an acid to give a salt and water.', keys: ['salt and water'], align: 'left', accent: C.cyan}); stage: a dish of powder (neutral grey) tips into the acid beaker on cue 'بتتفاعل'; tags 'salt' and 'water' appear in the glass on cues 'salt' / 'ومية'.","tts_text":"فيه مادة تانية اسمها base: بتتفاعل مع الـ acid وتدّي salt ومَيّة.","screen_text":"base: A substance that reacts with an acid to give a salt and water.","pause_after_s":0.8},{"id":"s2l11","visual":"Stage: a spoon of powder (neutral dark grey, no colour claim) with label 'copper (II) oxide' + YK.formula 'CuO' (mono 56) on cue 'copper'#1; inset: YK.atomDisc el 'Cu' joined to el 'O' (short bond line) on cue 'متحد'; tags 'copper' / 'oxygen' on their cues.","tts_text":"مثال أول: الـ copper two oxide، يعني copper متّحد مع oxygen كده.","screen_text":"copper (II) oxide, CuO: copper + oxygen","pause_after_s":0.4},{"id":"s2l12","visual":"YK.flashRect around '(II)' in the s2l11 label on cue 'two' + YK.tag '(II): part of the name' (36, textDim) under it; stage otherwise unchanged.","tts_text":"والـ two اللي في الاسم ده جزء من الاسم، وهتفهمه في الفصل.","screen_text":"(II): part of the name","pause_after_s":0.4},{"id":"s2l13","visual":"Second spoon (white powder) beside the first, label 'magnesium hydroxide' + YK.formula 'Mg(OH)_{2}' (mono 56) on cue 'magnesium'#1; inset: YK.atomDisc el 'Mg' with two O–H pairs (YK.atomDisc el 'O' + el 'H', bonded) attached; YK.bracket around one O–H pair with tag 'hydroxide group' on cue 'group'.","tts_text":"ومثال تاني: الـ magnesium hydroxide، يعني magnesium مع hydroxide group كده.","screen_text":"magnesium hydroxide, Mg(OH)₂: magnesium + hydroxide group","pause_after_s":0.4},{"id":"s2l14","visual":"Three YK.cube pieces (lab beats) slide in left → right, metallic shine sweep (C.steel / C.atomCu): tags 'copper', 'magnesium', 'sodium' on their cues; a gold YK.bracket groups them with tag 'metals' on cue 'metals'; a fourth plain iron bar (C.steel, no label) slides in on 'الحديد'.","tts_text":"والـ copper والـ magnesium والـ sodium من عيلة اسمها metals، زي الحديد.","screen_text":"copper · magnesium · sodium: metals","pause_after_s":0.4},{"id":"s2l15","visual":"Two-column board (YK.panel 820–1300 and 1340–1824): left header 'metal oxides' with 'CuO' (YK.formula), right header 'metal hydroxides' with 'Mg(OH)_{2}'; on cue 'bases' both columns get a cyan underline tag 'base'; the word 'Many' (gold, 44) pops on cue 'وكتير'.","tts_text":"وكتير من الـ metal oxides والـ metal hydroxides نوعهم bases برضه.","screen_text":"Many metal oxides and metal hydroxides are bases","pause_after_s":0.4},{"id":"s2l16","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 380, {term: 'alkali', def: 'A base that dissolves in water, giving hydroxide ions (OH^-).', keys: ['hydroxide ions'], align: 'left', accent: C.cyan}) on cue 'alkali'; stage: white pellets drop into a beaker of water and vanish (solid p 1 → 0) on cue 'داب'; zoom inset: O–H pairs with '-' charge badges spread out on cue 'hydroxide'; label 'OH^-' (YK.formula 48) on cue 'سالبة'.","tts_text":"ولو الـ base داب في المية وطلّع hydroxide ions سالبة، نسميه alkali، يعني قلوي.","screen_text":"alkali: A base that dissolves in water, giving hydroxide ions (OH⁻).","pause_after_s":0.8},{"id":"s2l17","visual":"Two beakers labelled 'sodium hydroxide' / 'ammonium hydroxide' with YK.formula 'NaOH' / 'NH4OH' (mono 48) on their cues; a litmus strip (same drawing as s2l9) dips in and turns blue (YK.mix to a plain blue '#3D6BFF': litmus blue as the lesson states) on cue 'أزرق'; tag 'litmus' on cue 'litmus'.","tts_text":"زي الـ sodium hydroxide، والـ ammonium hydroxide، ودول بيقلبوا الـ litmus أزرق.","screen_text":"sodium hydroxide NaOH · ammonium hydroxide NH₄OH · litmus → blue","pause_after_s":0.4},{"id":"s2l18","visual":"YK.predictCard(ctx, t, {at: YK.cueX('s2l18','طب'), until: YK.cue('s2l19') + 0.4, think: YK.cueEnd('s2l18'), end: YK.cue('s2l19'), kind: 'PREDICT', q: 'NaOH has hydrogen in its formula. Is it an acid?'}); stage: YK.formula 'NaOH' (mono 120) centre-stage, the H turns gold on cue 'hydrogen'. During the 3 s think ring nothing is answered.","tts_text":"طب الـ sodium hydroxide فيه hydrogen في الـ formula بتاعته؛ يبقى acid؟ فكّر.","screen_text":"PREDICT: NaOH has hydrogen in its formula. Acid?","pause_after_s":3},{"id":"s2l19","visual":"Misconception: YK.mythLine(ctx, t, {at: YK.cue('s2l19'), wrongAt: YK.cueX('s2l19','غلط'), until: YK.cueEnd('s2l21') + 1.5, text: 'Has hydrogen, so it is an acid', x: 96, y: 300, size: 48}) — coral text with ✕ (YK.wrongMark) from the «غلط» cue for its whole visible time; no strike-through.","tts_text":"فيه ناس بتقول: طالما فيه hydrogen يبقى acid، وده غلط.","screen_text":"Has hydrogen, so it is an acid","pause_after_s":0.4},{"id":"s2l20","visual":"Fix (held ≥ the myth): the big 'NaOH' formula splits into 'Na' + 'OH'; YK.bracket around 'OH' on cue 'hydroxide' with tag 'hydroxide group'; the gold H sits inside the bracket on cue 'hydrogen'. YK.fpara 'In NaOH, hydrogen is part of the hydroxide group' (44, mint) + YK.rightMark on cue 'جزء'. The myth line keeps its ✕.","tts_text":"الـ hydrogen هنا جزء من الـ hydroxide group نفسها، مش لوحده.","screen_text":"In NaOH, hydrogen is part of the hydroxide group ✓","pause_after_s":0.4},{"id":"s2l21","visual":"Zoom inset: NaOH particles in water release O–H pairs with '-' badges on cue 'hydroxide'; YK.answerSlot(ctx, t, {at: YK.cueX('s2l21','alkali'), text: 'alkali', x: 420, y: 760}); the s2l9/s2l17 litmus strip shows blue beside it.","tts_text":"وفي المية بيدّي hydroxide ions، يبقى ده alkali مش acid، واضح؟","screen_text":"NaOH gives hydroxide ions (OH⁻) in water → alkali ✓","pause_after_s":0.6},{"id":"s2l22","visual":"New picture: word line 'acid + base -> salt + water' (YK.formula 56, arrow gold) builds left → right on cues 'acid' / 'base' / 'salt' / 'ومية'; stage: an acid beaker and a base beaker pour into one glass (YK.beaker, level rises) on cue 'يدّوا'.","tts_text":"ودلوقتي الأهم: الـ acid مع الـ base يدّوا salt ومَيّة.","screen_text":"acid + base → salt + water","pause_after_s":0.6},{"id":"s2l23","visual":"YK.termCard(ctx, 96, 420, {term: 'salt', align: 'left'}) on cue 'salt' + YK.fpara 'a compound (atoms of more than one kind, joined)' (40) under it on cue 'compound'; stage: two different YK.atomDisc (el 'Na' and el 'Cl') click together on cue 'متحدين'; tag 'atom' on each disc on cue 'atom'.","tts_text":"الـ salt ده compound، يعني مادة فيها أكتر من نوع atom متحدين.","screen_text":"salt: a compound (atoms of more than one kind, joined)","pause_after_s":0.4},{"id":"s2l24","visual":"Definition card (lesson KeyTerm wording) replaces the s2l23 card: YK.termCard(ctx, 96, 340, {term: 'salt', def: 'A compound formed when the hydrogen of an acid is replaced by a metal (or ammonium).', keys: ['hydrogen of an acid', 'replaced by a metal'], align: 'left'}) on cue 'salt'; keys turn gold on cues 'hydrogen' / 'metal'. Stage particle swap (no written equation): an HCl pair (YK.atomDisc H + Cl); the H disc flies out (YK.flyer, trail) and a Na disc slides into its place on cue 'مكان'; tag 'metal' on Na on cue 'metal'; small tag 'or ammonium' (36, textDim) on cue 'ammonium'.","tts_text":"الـ salt compound بيتكوّن لما metal أو ammonium ياخد مكان hydrogen الـ acid بتاعه.","screen_text":"salt: A compound formed when the hydrogen of an acid is replaced by a metal (or ammonium).","pause_after_s":0.6},{"id":"s2l25","visual":"Second misconception: YK.mythLine(ctx, t, {at: YK.cue('s2l25'), wrongAt: YK.cueX('s2l25','غلط'), until: YK.cueEnd('s2l26') + 1.5, text: 'A salt is something salty you eat', x: 96, y: 300, size: 44}) with ✕ for its whole visible time, no strike-through; stage: the table-salt dish of s1 returns small with a faint ✕ (YK.wrongMark 90) on the same cue.","tts_text":"وفيه ناس فاكرة إن أي salt بيتاكل وطعمه مالح، وده غلط.","screen_text":"A salt is something salty you eat","pause_after_s":0.4},{"id":"s2l26","visual":"Fix (held ≥ the myth): a heap of crystals (neutral, no colour claim) labelled 'copper (II) sulphate' on cue 'copper'; YK.tag 'salt' on cue 'salt'; a small bug drawn page-local (ctx paths) inside a mint ring on cue 'مبيد' (book p.7: copper II sulphate used as insecticide); YK.rightMark next to the fix line 'copper (II) sulphate: a salt nobody eats' (YK.fpara 44, mint) on cue 'بياكله'. The myth line keeps its ✕.","tts_text":"الـ copper two sulphate ده salt، ومحدش بياكله، بيستخدموه مبيد حشري.","screen_text":"copper (II) sulphate: a salt nobody eats ✓","pause_after_s":0.6},{"id":"s2l27","visual":"Naming board in the text panel: YK.fpara 'salt name = metal (from the base) + ending (from the acid)' (44) builds on cues 'metal' / 'base' / 'acid'; stage: a name plate split in two halves (YK.panel), left half glows cyan on 'base', right half amber on 'acid'.","tts_text":"اسم الـ salt أوله الـ metal من الـ base، وآخره من الـ acid نفسه.","screen_text":"salt name = metal (from the base) + ending (from the acid)","pause_after_s":0.4},{"id":"s2l28","visual":"Three-row table on the stage (YK.panel rows, LTR): row 1 'hydrochloric acid → chlorides' with YK.formula 'HCl' builds on cues 'hydrochloric' / 'chlorides'; the shared 'Cl' pulses gold in both columns.","tts_text":"الـ hydrochloric acid بيدّي salts اسمها chlorides كده.","screen_text":"hydrochloric acid → chlorides","pause_after_s":0.4},{"id":"s2l29","visual":"Rows 2 and 3: 'sulphuric acid → sulphates' with 'H2SO4' on cues 'sulphuric' / 'sulphates', 'nitric acid → nitrates' with 'HNO3' on cues 'nitric' / 'nitrates'; the shared 'SO4' / 'NO3' groups pulse gold (YK.pulseA).","tts_text":"والـ sulphuric acid بيدّي sulphates، والـ nitric acid بيدّي nitrates كده.","screen_text":"sulphuric acid → sulphates · nitric acid → nitrates","pause_after_s":1},{"id":"s3l2","visual":"Stage: a YK.beaker labelled 'sodium hydroxide' (YK.formula 'NaOH') on cue 'sodium'; a second glass labelled 'hydrochloric acid' (tag 'dilute' 32) tilts above it on cue 'hydrochloric'. The worked steps stack in the text panel (YK.list, LTR, at = word cues).","tts_text":"عندنا sodium hydroxide، وهنضيف عليه hydrochloric acid من النوع الـ dilute ده.","screen_text":"sodium hydroxide + dilute hydrochloric acid","pause_after_s":0.4},{"id":"s3l3","visual":"YK.list item 1 'sodium hydroxide → alkali → base' builds on cues 'sodium' / 'alkali' / 'base' (arrows gold via YK.formula '->'); the s2 alkali card flashes small top-right of the stage (YK.flashRect) as a callback.","tts_text":"أول خطوة: الـ sodium hydroxide ده alkali، يعني base، يبقى هيتفاعل.","screen_text":"Step 1: sodium hydroxide → alkali → base","pause_after_s":0.4},{"id":"s3l4","visual":"The acid pours in (level rises, no bubbles: bubbles 0) on cue 'acid'; YK.list item 2 'base + acid → salt + water' on cues 'salt' / 'ومية'.","tts_text":"والـ base مع الـ acid يدّوا salt ومَيّة، زي ما قلنا.","screen_text":"Step 2: base + acid → salt + water","pause_after_s":0.4},{"id":"s3l5","visual":"Inset particle picture: YK.atomDisc el 'Na' lifts out of the NaOH particle on cue 'base' and gets tag 'metal' on cue 'metal', 'sodium' on cue 'sodium'; YK.list item 3.","tts_text":"الـ metal جاي من الـ base، وهو الـ sodium هنا.","screen_text":"Step 3: metal from the base: sodium","pause_after_s":0.4},{"id":"s3l6","visual":"The 'hydrochloric acid → chlorides' row from s2l29's table flashes (callback); a Cl disc leaves the HCl particle on cue 'chloride' and joins the Na disc; YK.list item 4.","tts_text":"والنهاية من الـ acid: الـ hydrochloric acid بيدّي chloride كده.","screen_text":"Step 4: ending from the acid: hydrochloric → chloride","pause_after_s":0.4},{"id":"s3l7","visual":"Na + Cl discs settle together; label 'sodium chloride' (56, gold) on cue 'sodium'; the s1 table-salt dish returns beside it on cue 'ملح' with YK.rightMark; tag 'table salt' on the dish.","tts_text":"يبقى الـ salt اسمه sodium chloride، وده ملح الأكل اللي بدأنا بيه.","screen_text":"salt: sodium chloride = table salt","pause_after_s":0.4},{"id":"s3l8","visual":"Particle picture in the inset: the H disc that left HCl (YK.flyer, trail) meets the O–H pair from NaOH on cue 'hydroxide' and they become YK.molecule({formula: 'H2O', r: 40}) on 'المية'; tags 'hydrogen' / 'hydroxide' on their cues, 'water' under the molecule.","tts_text":"والـ hydrogen بتاع الـ acid، مع الـ hydroxide بتاع الـ base، يعملوا المية.","screen_text":"water: hydrogen (from the acid) + hydroxide (from the base)","pause_after_s":0.4},{"id":"s3l9","visual":"The one written equation of the video (lesson notation): YK.formula(ctx, 'NaOH + HCl -> NaCl + H2O', 1307, 560, {size: 72, align: 'center'}) reveals from cue 'alkali' to cue 'ومية'; YK.bracket under 'NaOH' on 'alkali', under 'HCl' on 'acid', under 'NaCl' on 'salt', under 'H2O' on 'ومية'.","tts_text":"ودي المعادلة: الـ alkali مع الـ acid، يدّوا salt ومَيّة.","screen_text":"NaOH + HCl → NaCl + H₂O","pause_after_s":1},{"id":"s3l10","visual":"Self-check on a NEW case (not the worked example): stage clears; a spoon of white powder labelled 'magnesium hydroxide' over a YK.beaker labelled 'hydrochloric acid' (tag 'dilute' 32) on cue 'magnesium'. YK.predictCard(ctx, t, {at: YK.cue('s3l10'), until: YK.cue('s3l12') + 0.4, think: YK.cueEnd('s3l11'), end: YK.cue('s3l12'), kind: 'QUICK CHECK', q: 'Magnesium hydroxide + dilute hydrochloric acid: which salt forms? What else?'}).","tts_text":"دورك: الـ magnesium hydroxide مع الـ hydrochloric acid الـ dilute ده.","screen_text":"Your turn: magnesium hydroxide + dilute hydrochloric acid","pause_after_s":0.4},{"id":"s3l11","visual":"The question stays; YK.checkPause(ctx, 1307, 860, {t, start: YK.cueEnd('s3l11'), dur: 4}) think ring + countdown through the silence; only the question shows (no answer, no hint) during the pause.","tts_text":"إيه اسم الـ salt اللي هيتكوّن؟ وإيه كمان؟ وقّف الفيديو وفكّر.","screen_text":"Which salt forms? What else forms?","pause_after_s":4},{"id":"s3l12","visual":"Answer: the powder drops in and dissolves (solid p 1 → 0, bubbles 0) on cue 'الإجابة'; YK.answerSlot(ctx, t, {at: YK.cueX('s3l12','magnesium'), text: 'magnesium chloride + water', x: 420, y: 700}); tag 'salt' on cue 'salt'.","tts_text":"الإجابة: salt اسمه magnesium chloride، ومعاه مَيّة كمان.","screen_text":"magnesium chloride + water ✓","pause_after_s":0.4},{"id":"s3l13","visual":"Reason as two YK.list lines under the answer: 'magnesium ← base' on cue 'magnesium' (cyan), 'chloride ← hydrochloric acid' on cue 'chloride' (amber); the naming plate of s2l27 returns small with both halves filled; YK.rightMark.","tts_text":"الـ magnesium جاي من الـ base، والـ chloride جاي من الـ hydrochloric acid نفسه.","screen_text":"magnesium from the base · chloride from hydrochloric acid","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, 'Acidic and basic oxides', {kind: 'concept', align: 'left'}) (map title_en exactly) on cue 'acidic'; small YK.tag 'base' (40, cyan) beside it on cue 'base'.","tts_text":"أول درس: الـ acidic والـ basic oxides، وهتحتاج فيه الـ base كويس.","screen_text":"Acidic and basic oxides","pause_after_s":0.4},{"id":"s4l3","visual":"Word line under the chip: 'metal oxides as bases -> salt + water' (YK.formula 44) lights on cues 'metal' / 'base' / 'salt' / 'ومية'; the s2l15 metal-oxides column thumbnail flashes (callback, no new example).","tts_text":"هناك هتشوف metal oxides بتتصرف زي الـ base، وتدّي salt ومَيّة.","screen_text":"metal oxides as bases → salt + water","pause_after_s":0.4},{"id":"s4l4","visual":"Second YK.chip(ctx, 820, 460, 'Metal + dilute acid', {kind: 'concept', align: 'left'}) on cue 'metal'; the s2l27 naming plate (metal | ending) pulses on 'القاعدة'. No products drawn (what else forms is taught in that lesson).","tts_text":"تاني درس: الـ metal مع الـ dilute acid، وهتسمي الـ salts بنفس القاعدة.","screen_text":"Metal + dilute acid","pause_after_s":0.4},{"id":"s4l5","visual":"Under the second chip: YK.tag 'chlorides' and 'sulphates' (40, amber) on their cues; a small '…' tag (textDim) on 'والباقي'. No equation.","tts_text":"يعني هتقابل chlorides و sulphates تاني، والباقي هتعرفه في الفصل.","screen_text":"chlorides · sulphates","pause_after_s":0.4},{"id":"s4l6","visual":"Third YK.chip(ctx, 820, 700, 'Types of chemical reactions', {kind: 'concept', align: 'left'}) on cue 'chemical'; tag 'acid + base' (40) beside it on cues 'acid' / 'base' (no new name for the reaction).","tts_text":"وتالت درس: أنواع الـ chemical reactions، والـ acid مع الـ base واحد منها.","screen_text":"Types of chemical reactions","pause_after_s":0.8},{"id":"s4l7","visual":"Recap (s4l7–s4l9 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l7'), until: YK.cue('s4l9'), title: 'Acids, bases and salts', line: 'Acid -> hydrogen ions (H^+) · alkali -> hydroxide ions (OH^-)', pulse: [{word: 'Acid', at: YK.cueX('s4l7','acid')}, {word: 'alkali', at: YK.cueX('s4l7','alkali')}]}); stage: the litmus strips (red / blue) return small.","tts_text":"الخلاصة: الـ acid بيدّي hydrogen ions، والـ alkali بيدّي hydroxide ions في المية.","screen_text":"Acid → hydrogen ions (H⁺) · alkali → hydroxide ions (OH⁻)","pause_after_s":0.4},{"id":"s4l8","visual":"Same recap card, second line 'Salt name: metal from the base + ending from the acid' added on cue 'salt'; the naming plate glows.","tts_text":"واسم الـ salt: الـ metal من الـ base، والنهاية من الـ acid بتاعه.","screen_text":"Salt name: metal from the base + ending from the acid","pause_after_s":0.6},{"id":"s4l9","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Acids, bases and salts', line: 'Acid + base → salt + water.', t, pulse: [{word: 'Acid', at: YK.cueX('s4l9','acid')}, {word: 'base', at: YK.cueX('s4l9','base')}, {word: 'salt', at: YK.cueX('s4l9','salt')}, {word: 'water', at: YK.cueX('s4l9','ومية')}]}) held ≥ 2.5 s; no fade to black, no outro.","tts_text":"يعني acid مع base، يدّوا salt ومَيّة.","screen_text":"Acid + base → salt + water.","pause_after_s":1.5}],"logline":"هتعرف يعني إيه acid و base و alkali، وإزاي الـ acid مع الـ base يدّوا salt ومية، وتسمّي الـ salt من الـ metal والـ acid.","segments":[{"id":"s1","title":"Lemons, vinegar and table salt","concept_id":"chem.acids-bases-salts"},{"id":"s2","title":"Acids, bases, alkalis and salts","concept_id":"chem.acids-bases-salts"},{"id":"s3","title":"Naming the salt of a reaction","concept_id":"chem.acids-bases-salts"},{"id":"s4","title":"Where Chapter 1 uses acids, bases and 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طعم الليمون والخل طعمهم حامض صح\nالحموضة دي جاية من مادة جواهم اسمها acid\nيعني حمض\nإنما في المعمل إوعى تدوق أي acid دي قاعدة\nمهمة\nودلوقتي ملح الأكل اللي على السفرة اسمه في\nالكيميا salt برضه\nالـ salt في الكيميا عيلة كبيرة وملح الأكل\nواحد من أفرادها\nوملح الأكل ليه formula يعني اسمه مكتوب\nبرموز قصيرة\nالرمز ده معناه sodium مع chlorine وده اسمه\nsodium chloride كده\nوهنقابل رمز تاني كتير الـ hydrogen وده غاز\nخفيف جدًا\nيبقى معانا تلات كلمات acid و salt و\nformula خلّيهم في بالك\nفي المعمل فيه acids أشهرها الـ\nhydrochloric acid والـ sulphuric acid كمان\nوالـ nitric acid وكل واحد منهم فيه\nhydrogen في الـ formula بتاعته\nوالـ acid بنستخدمه dilute يعني متخفف\nبمَيّة كتير\nلما الـ acid يدوب في المية بيطلّع ions جوه\nالمية\nوالـ atom ده حتة صغيرة جدًا بتتبني منها\nالمواد\nالـ ion ده atom أو مجموعة atoms عليه\nelectric charge يعني شُحنة\nيبقى الـ acid مادة بتدّي hydrogen ions\nموجبة لما تدوب في المية\nوكمان الـ acid بيقلب ورقة الـ litmus للون\nالأحمر\nفيه مادة تانية اسمها base بتتفاعل مع الـ\nacid وتدّي salt ومَيّة\nمثال أول الـ copper two oxide يعني copper\nمتّحد مع oxygen كده\nوالـ two اللي في الاسم ده جزء من الاسم\nوهتفهمه في الفصل\nومثال تاني الـ magnesium hydroxide يعني\nmagnesium مع hydroxide group كده\nوالـ copper والـ magnesium والـ sodium من\nعيلة اسمها metals زي الحديد\nوكتير من الـ metal oxides والـ metal\nhydroxides نوعهم bases برضه\nولو الـ base داب في المية وطلّع hydroxide\nions سالبة نسميه alkali يعني قلوي\nزي الـ sodium hydroxide والـ ammonium\nhydroxide ودول بيقلبوا الـ litmus أزرق\nطب الـ sodium hydroxide فيه hydrogen في\nالـ formula بتاعته يبقى acid فكّر\nفيه ناس بتقول طالما فيه hydrogen يبقى acid\nوده غلط\nالـ hydrogen هنا جزء من الـ hydroxide\ngroup نفسها مش لوحده\nوفي المية بيدّي hydroxide ions يبقى ده\nalkali مش acid واضح\nودلوقتي الأهم الـ acid مع الـ base يدّوا\nsalt ومَيّة\nالـ salt ده compound يعني مادة فيها أكتر\nمن نوع atom متحدين\nالـ salt compound بيتكوّن لما metal أو\nammonium ياخد مكان hydrogen الـ acid بتاعه\nوفيه ناس فاكرة إن أي salt بيتاكل وطعمه\nمالح وده غلط\nالـ copper two sulphate ده salt ومحدش\nبياكله بيستخدموه مبيد حشري\nاسم الـ salt أوله الـ metal من الـ base\nوآخره من الـ acid نفسه\nالـ hydrochloric acid بيدّي salts اسمها\nchlorides كده\nوالـ sulphuric acid بيدّي sulphates والـ\nnitric acid بيدّي nitrates كده\nعندنا sodium hydroxide وهنضيف عليه\nhydrochloric acid من النوع الـ dilute ده\nأول خطوة الـ sodium hydroxide ده alkali\nيعني base يبقى هيتفاعل\nوالـ base مع الـ acid يدّوا salt ومَيّة زي\nما قلنا\nالـ metal جاي من الـ base وهو الـ sodium\nهنا\nوالنهاية من الـ acid الـ hydrochloric acid\nبيدّي chloride كده\nيبقى الـ salt اسمه sodium chloride وده ملح\nالأكل اللي بدأنا بيه\nوالـ hydrogen بتاع الـ acid مع الـ\nhydroxide بتاع الـ base يعملوا المية\nودي المعادلة الـ alkali مع الـ acid يدّوا\nsalt ومَيّة\nدورك الـ magnesium hydroxide مع الـ\nhydrochloric acid الـ dilute ده\nإيه اسم الـ salt اللي هيتكوّن وإيه كمان\nوقّف الفيديو وفكّر\nالإجابة salt اسمه magnesium chloride ومعاه\nمَيّة كمان\nالـ magnesium جاي من الـ base والـ\nchloride جاي من الـ hydrochloric acid نفسه\nطب الكلام ده هيفيدك فين في الفصل\nأول درس الـ acidic والـ basic oxides\nوهتحتاج فيه الـ base كويس\nهناك هتشوف metal oxides بتتصرف زي الـ base\nوتدّي salt ومَيّة\nتاني درس الـ metal مع الـ dilute acid\nوهتسمي الـ salts بنفس القاعدة\nيعني هتقابل chlorides و sulphates تاني\nوالباقي هتعرفه في الفصل\nوتالت درس أنواع الـ chemical reactions\nوالـ acid مع الـ base واحد منها\nالخلاصة الـ acid بيدّي hydrogen ions والـ\nalkali بيدّي hydroxide ions في المية\nواسم الـ salt الـ metal من الـ base\nوالنهاية من الـ acid بتاعه\nيعني acid مع base يدّوا salt ومَيّة","countable":false,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":84,"see_also":[{"item_id":"chem-s3-en.lesson-te.uses-v-cr","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Economic importance of vanadium and chromium","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":147.76,"kind":"pause_question","spec":{"answer":"لأ: الـ hydrogen هنا جزء من الـ hydroxide group؛ الـ NaOH بيدّي hydroxide ions (OH⁻) في المية، فهو alkali.","prompt":"الـ NaOH فيه hydrogen في الـ formula بتاعته: يبقى acid؟","options":[{"id":"a","text":"لأ","correct":true},{"id":"b","text":"أيوه، طالما فيه hydrogen","correct":false}],"answer_t_s":151.73,"concept_id":"chem.acids-bases-salts"},"content_lang":"ar-EG"},{"id":"think-2","t_s":263.61,"kind":"pause_question","spec":{"answer":"magnesium chloride + water: الـ metal من الـ base (magnesium)، والـ ending من الـ acid (chloride).","prompt":"magnesium hydroxide + dilute hydrochloric acid: إيه اللي بيتكوّن؟","options":[{"id":"a","text":"magnesium chloride + water","correct":true},{"id":"b","text":"magnesium sulphate + water","correct":false},{"id":"c","text":"magnesium chloride + hydrogen","correct":false}],"answer_t_s":267.63,"concept_id":"chem.acids-bases-salts"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.acids-bases-salts"]},{"id":"chem-s3-en.video-walkthrough-chem.oxides","kind":"walkthrough","version":6,"ord":92,"content_lang":"ar-EG","primary_concept_id":"chem.oxides","concepts":[{"concept_id":"chem.oxides","role":"primary"}],"title":"Acidic and basic oxides: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.oxides v1 (hook s1: rust vs iron in dilute hydrochloric acid; s2 KeyTerm 'Basic oxide' + CuO + H2SO4 formula; s3 KeyTerm 'Acidic oxide', Callout 'Say most… Al2O3 reacts with acids and with bases too', examples Na2O, MgO, CuO, CO2, SO3; s5 recap); concept chem.oxides v3 summaries (no recorded misconceptions: s2 refutes the lesson's hook misconception 'iron oxide fizzes like iron' and the 'most, not all' overgeneralization); prereq summaries chem.metal-properties (metals shiny, conduct heat and electricity; non-metals mostly lack these) and chem.acids-bases-salts; book p.21 (Fe + dilute HCl / H2SO4 -> iron (II) salt + H2), p.22 (FeO + H2SO4 ->(dil.) FeSO4 + H2O; FeO black powder), p.22-23 (Fe2O3 + hot conc. mineral acids -> iron (III) salts + water). Dependents named in s4 (in-book): 'Iron(II) oxide FeO', 'Iron(III) oxide Fe₂O₃' (map titles); not-in-book dependents (rusting, redox.basic) are not named to avoid new terms in s4. Terms (defined at first use): s1 metal, oxide, acid (3); s2 dilute, salt, basic oxide, base, non-metals, acidic oxide. Rust is said in Arabic («الصدا») only, never labelled Fe2O3 (avoids fe.oxide-fe2o3.mc2). Voicing: compound names with an Arabic numeral inside («copper اتنين oxide», «iron تلاتة oxide») per chem-s3-en.voice.groups-configs; 'aluminum' and 'sulphur/sulphuric' spellings per edition. One written equation (s3l7, lesson notation, condition over the arrow as the book writes it for FeO); other reactions are particle pictures or word lines. Self-check: NEW case MgO + dilute HCl (worked example is CuO + dilute H2SO4). Predicts: s2l4 (~1:05), s3l8-9 (~3:20). not-in-source: lemon and vinegar taste sour because they contain acids; fizzy drinks are carbon dioxide dissolved in water and taste slightly sharp because it makes an acid; a salt contains the metal and part of the acid (plain-language meaning, no definition card); base = the opposite of an acid, it cancels its sourness (plain meaning); CuO reacts with DILUTE sulphuric acid (lesson gives no strength; scoped per chem-s3-en.fact.acids-electrochem); MgO + dilute HCl -> magnesium chloride + water, no gas; rust forms when iron stays in moist air (concept chem.rusting-corrosion summary: oxygen and moisture). Estimated duration ≈ 299 s (≈ 4:59; 588 words at ~2.4 words/s + 40.6 s pauses + joins); planning aid only.","title":"Acidic and basic oxides: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Camera (YK.camera) pushes in on the nail; YK.tag 'iron' (44) points to the clean part of the shank on cue 'iron'; YK.rain-style drops (YK.drop ×3, C.cyan, alpha 0.5) drift past on cue 'الرطب' to show moist air.","tts_text":"بص على مسمار قديم من الـ iron، سايبينه في الهوا الرطب شهور.","screen_text":"An old iron nail","pause_after_s":0.4},{"id":"s1l3","visual":"YK.flashRect around the crust on cue 'الصدا'; YK.fpara 'Months in moist air' (44, textDim) in the text panel (96, 260). No English label on the crust (the Arabic word is not a term on screen).","tts_text":"الطبقة الخشنة اللي عليه دي هي الصدا اللي نعرفه.","screen_text":"Months in moist air","pause_after_s":0.4},{"id":"s1l4","visual":"YK.zoomThrough(ctx, t, {from: drawNail, to: drawGrid, focus: crust, badge: '×10^8'}) starting on cue 'الصدا': the crust opens into a small alternating grid of YK.atomDisc el 'Fe' and el 'O' (r 46); YK.tag 'iron' on an Fe disc on cue 'iron', YK.tag 'oxygen' on an O disc on cue 'oxygen'; a few O discs float in from the top edge (air) on 'بنتنفسه'. YK.scaleBadge in the stage corner.","tts_text":"الصدا ده iron اتّحد مع الـ oxygen، الغاز اللي بنتنفسه.","screen_text":"iron + oxygen (from the air)","pause_after_s":0.4},{"id":"s1l5","visual":"YK.termCard(ctx, 96, 420, {term: 'oxide', align: 'left', p: on cue 'oxide'}) (no def: the book gives none); under it YK.formula 'iron + oxygen -> iron oxide' (mono 48) reveals left → right on cues 'oxygen' / 'iron'#1; the atom grid on the stage stays, tag 'iron oxide' (48) above it on cue 'oxide'#1.","tts_text":"أي عنصر يتّحد مع الـ oxygen، الناتج اسمه oxide، والصدا ده iron oxide كده.","screen_text":"oxide · iron + oxygen → iron oxide","pause_after_s":0.6},{"id":"s1l6","visual":"Stage: clean iron bar (YK.cube, C.steel, glow 0.3 shine sweep) on cue 'لامع', a small circuit with a lamp YK.icon('lamp') that lights through the bar on 'الكهربا'. YK.termCard(ctx, 96, 420, {term: 'metal', align: 'left'}) on cue 'metal' + YK.fpara 'shiny, conducts heat and electricity' (40) under it.","tts_text":"الـ iron ده metal، يعني لامع وبيوصّل الكهربا والحرارة.","screen_text":"metal: shiny, conducts heat and electricity","pause_after_s":0.4},{"id":"s1l7","visual":"Two more YK.cube pieces slide in beside the iron bar (left → right): copper (C.atomCu) on cue 'copper', magnesium (C.steel, lighter) on cue 'magnesium'; YK.tag under each ('copper', 'magnesium'); a gold YK.bracket groups all three with tag 'metal' on cue 'metal'.","tts_text":"وكمان الـ copper والـ magnesium نوعهم metal، زي الـ iron بالظبط.","screen_text":"copper, magnesium: metal","pause_after_s":0.4},{"id":"s1l8","visual":"New picture (stage cleared, metals dim to 35% at the left edge): a lemon slice (page-local ctx arcs, flat yellow segments) and a vinegar bottle silhouette (ctx path, clear glass) pop in on cues 'الليمون' / 'والخل'; labels 'lemon' / 'vinegar' (40) under them.","tts_text":"الليمون والخل طعمهم حامض، صح؟","screen_text":"lemon · vinegar","pause_after_s":0.6},{"id":"s1l9","visual":"YK.termCard(ctx, 96, 420, {term: 'acid', align: 'left'}) on cue 'acid'; small YK.dot particles (C.amber, YK.swarm) glow inside the lemon and the bottle on the same cue.","tts_text":"الحموضة دي جاية من مادة اسمها acid جواهم.","screen_text":"acid","pause_after_s":0.4},{"id":"s1l10","visual":"Lemon and bottle slide out left; two YK.beaker(ctx, x, 720, 300, 380, {level: 0.6, color: 'rgba(120,160,255,0.35)'}) slide in from the left on cue 'المعمل', labels under the glasses (YK.beaker label) 'hydrochloric acid' on its cue and 'sulphuric acid' on its cue (labels as names, no formulas yet).","tts_text":"وفي المعمل فيه acids أقوى، زي الـ hydrochloric acid والـ sulphuric acid كمان.","screen_text":"hydrochloric acid · sulphuric acid","pause_after_s":0.4},{"id":"s1l11","visual":"Micro-recap: the three term cards collapse into three YK.chip kind 'concept' in a row in the text panel (96, 300 / 420 / 540) on the cues 'metal', 'oxide', 'acid'; stage: iron bar, iron oxide grid, acid beaker thumbnails light in the same order (YK.flashRect).","tts_text":"يبقى معانا تلات كلمات: metal و oxide و acid، خلّيهم في بالك.","screen_text":"metal · oxide · acid","pause_after_s":1},{"id":"s2l2","visual":"Stage: one YK.beaker of acid (level 0.25) on cue 'acid'; water pours in from a second glass (YK.flyer droplets C.cyan) and the level rises 0.25 → 0.7 on 'متخفف'. YK.termCard(ctx, 96, 420, {term: 'dilute', align: 'left'}) on cue 'dilute' + YK.fpara 'acid + a lot of water' (40).","tts_text":"الـ acid اللي هنستخدمه dilute، يعني متخفف بمَيّة كتير.","screen_text":"dilute: acid + a lot of water","pause_after_s":0.4},{"id":"s2l3","visual":"Two YK.beaker side by side on the stage (x 1050 / 1550, y 720, 340×420), both labelled 'hydrochloric acid' (the dilute acid of s2l2). Left: a piece of iron drops in (solid:{color: C.steel}) on cue 'iron', bubbles 0 → 0.9 from 'بتفوّر' (from:'solid'); YK.tag 'hydrogen' (44) rises with the bubbles on cue 'hydrogen'. Right glass stays empty for now. Book p.21: iron dissolves in dilute mineral acids giving hydrogen.","tts_text":"حُطّ حتة iron في الـ hydrochloric acid، تلاقيها بتفوّر وتطلّع hydrogen، غاز خفيف.","screen_text":"Iron + hydrochloric acid: fizzes → hydrogen","pause_after_s":0.4},{"id":"s2l4","visual":"YK.predictCard(ctx, t, {at: YK.cueX('s2l4','طب'), until: YK.cue('s2l5') + 0.4, think: YK.cueEnd('s2l4'), end: YK.cue('s2l5'), kind: 'PREDICT', q: 'Iron oxide in the acid: will it fizz and give hydrogen?'}); stage: a lump of iron oxide (YK.ore seed 5) hovers above the right glass on cue 'iron', label 'iron oxide'. Think ring runs through the 3 s silence; nothing is answered on screen during it.","tts_text":"طب الصدا، يعني الـ iron oxide، في الـ acid، هيفوّر ويطلّع hydrogen؟ فكّر.","screen_text":"PREDICT: iron oxide in the acid. Fizz?","pause_after_s":3},{"id":"s2l5","visual":"Answer: the lump drops into the right glass on cue 'لأ' and shrinks (solid p 1 → 0) from 'بيدوب'; bubbles stay 0 in that glass while the left glass keeps fizzing (contrast held). YK.answerSlot(ctx, t, {at: YK.cue('s2l5','غاز'), text: 'No gas: it dissolves', x: 420, y: 760}).","tts_text":"لأ، الـ iron oxide بيدوب في الـ acid من غير أي غاز.","screen_text":"No gas: it dissolves","pause_after_s":0.6},{"id":"s2l6","visual":"Misconception: YK.mythLine(ctx, t, {at: YK.cue('s2l6'), wrongAt: YK.cueX('s2l6','غلط'), until: YK.cueEnd('s2l7') + 1.5, text: 'Iron oxide fizzes like iron', x: 96, y: 300, size: 48}) — coral text with ✕ (YK.wrongMark) from the «غلط» cue for the whole time it is visible (no strike-through). Stage: a ghost of bubbles over the right glass drawn faintly, crossed by YK.wrongMark(ctx, 1550, 560, 120) on the same cue.","tts_text":"فيه ناس فاكرة إن الـ iron oxide هيفوّر زي الـ iron، وده غلط.","screen_text":"Iron oxide fizzes like iron","pause_after_s":0.4},{"id":"s2l7","visual":"Fix (held ≥ the myth): zoom inset (YK.panel 1180, 200, 560, 360) shows the Fe–O atom grid of s1l4 (YK.atomDisc Fe + O, bonds as short lines) on cue 'iron'; each Fe disc pulses linked to an O on 'متحد'; YK.rightMark next to the fix line 'Iron is combined with oxygen, not free metal' (YK.fpara 44, mint, 96, 420) on cue 'حر'. The myth line stays visible with its ✕ above it.","tts_text":"الـ iron هنا متّحد مع الـ oxygen، مش metal حر لوحده.","screen_text":"Iron is combined with oxygen, not free metal ✓","pause_after_s":0.6},{"id":"s2l8","visual":"Particle picture (no written equation): in the inset, YK.atomDisc el 'H' pairs fly in from the acid side (YK.flyer, trail) on cue 'hydrogen', meet an O disc pulled out of the grid on cue 'oxygen', and become YK.molecule({formula: 'H2O', r: 40}) on 'مية'; tags 'acid's hydrogen', 'oxide's oxygen' (36) on their cues, 'water' (44) under the molecule.","tts_text":"الـ hydrogen بتاع الـ acid بيمسك في الـ oxygen بتاع الـ oxide، ويعمل مَيّة.","screen_text":"acid's hydrogen + oxide's oxygen → water","pause_after_s":0.4},{"id":"s2l9","visual":"The remaining Fe disc joins the leftover acid particles (YK.dot C.amber, labelled nothing) into a small cluster on cue 'بتتجمع'; YK.termCard(ctx, 96, 420, {term: 'salt', align: 'left'}) on cue 'salt' + YK.fpara 'not just table salt' (40, textDim) on 'الأكل'.","tts_text":"وباقي الحاجات بتتجمع في مادة اسمها salt، مش شرط ملح الأكل.","screen_text":"salt: not just table salt","pause_after_s":0.4},{"id":"s2l10","visual":"YK.bracket around the Fe disc + amber acid-part dots (the salt cluster) drawn left → right on cue 'salt'; tags 'metal' on the Fe disc on cue 'metal' and 'part of the acid' on the amber dots on cue 'acid'.","tts_text":"الـ salt ده بيبقى فيه الـ metal، وجزء من الـ acid برضه.","screen_text":"salt: the metal + part of the acid","pause_after_s":0.4},{"id":"s2l11","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 380, {term: 'basic oxide', def: 'A metal oxide that reacts with an acid to give a salt and water.', keys: ['salt and water'], align: 'left', p: on cue 'basic'}); stage: the s2 right glass returns with tags 'salt' and 'water' inside on cues 'salt' / 'ومية'.","tts_text":"الـ metal oxide ده اسمه basic oxide: مع الـ acid يدّي salt ومَيّة.","screen_text":"basic oxide: A metal oxide that reacts with an acid to give a salt and water.","pause_after_s":0.8},{"id":"s2l12","visual":"YK.termCard(ctx, 96, 760, {term: 'base', align: 'left'}) on cue 'base' + YK.fpara 'the opposite of an acid' (40); stage: YK.balance(ctx, 1300, 640, 600, {left: 'acid', right: 'base', value: 1 → 0 (level) from cue 'وبيلغي'}) — the base side cancels the acid side; the word 'basic' in the termCard pulses gold on cue 'basic' (link between the names).","tts_text":"واسمه basic عشان بيتصرف زي الـ base: عكس الـ acid، وبيلغي حموضته.","screen_text":"basic ← base: the opposite of an acid","pause_after_s":0.4},{"id":"s2l13","visual":"Left column of a two-column board starts on the stage (YK.panel 820–1300, accent C.cyan): header 'metal oxides → basic oxides' on cue 'metal'; 'Most' (gold, 40) on cue 'ومعظم'; YK.formula row 'CuO   Na2O   FeO' (mono 56) and tag 'iron oxide' on cue 'iron'.","tts_text":"ومعظم الـ metal oxides، زي الـ iron oxide، بتبقى basic oxides برضه.","screen_text":"Most metal oxides → basic oxides","pause_after_s":0.4},{"id":"s2l14","visual":"Second misconception: YK.mythLine(ctx, t, {at: YK.cue('s2l14'), wrongAt: YK.cueX('s2l14','كلهم'), until: YK.cueEnd('s2l15') + 1.5, text: 'All metal oxides basic?', x: 96, y: 300, size: 44}) with ✕ (YK.wrongMark) for its whole visible time, no strike-through; the fix 'Most' + YK.rightMark (48, mint) beside it on cue 'معظم', held through s2l15; the word 'Most' in the left column header flashes gold (YK.pulseA) on the same cue.","tts_text":"وخلّي بالك: بنقول معظم الـ metal oxides بتبقى basic، مش كلهم.","screen_text":"All metal oxides basic? ✕  Most ✓","pause_after_s":0.4},{"id":"s2l15","visual":"The reason for 'Most' (myth line of s2l14 and its ✕ stay visible): YK.formula 'Al2O3' (mono 64) in the left column with two YK.flow arrows to tags 'acid' and 'base' on cues 'acid' / 'base' + YK.rightMark next to 'reacts with acids and with bases' (40, mint). Lesson s3 callout.","tts_text":"الـ aluminum oxide مثلًا بيتفاعل مع الـ acid، ومع الـ base كمان.","screen_text":"aluminum oxide Al₂O₃: reacts with acids and with bases","pause_after_s":0.4},{"id":"s2l16","visual":"New picture: right column of the board (YK.panel 1340–1824, accent C.amber) appears; a dull yellow sulphur lump (YK.ore seed 9, flat, no shine) and a carbon lump (C.atomC) on cue 'عناصر'; YK.termCard(ctx, 96, 420, {term: 'non-metals', align: 'left'}) on cue 'non'.","tts_text":"وفيه عناصر تانية أغلبها مش لامع، اسمها non-metals كده.","screen_text":"non-metals","pause_after_s":0.4},{"id":"s2l17","visual":"YK.tag 'sulphur' and 'carbon' under the two lumps on their cues; YK.bracket groups them with tag 'non-metals' on cue 'non'.","tts_text":"زي الـ sulphur والـ carbon، ودول من الـ non-metals دي.","screen_text":"sulphur, carbon: non-metals","pause_after_s":0.4},{"id":"s2l18","visual":"Everyday anchor: a glass of fizzy drink (YK.beaker, clear liquid, bubbles 0.6 from bottom, t) on cue 'فقاقيع'; YK.molecule({formula: 'CO2', r: 34}) ×3 drift up with the bubbles on cue 'carbon'; tag 'carbon dioxide CO2' (YK.formula, 44) on the same cue.","tts_text":"فاكر فقاقيع الحاجة الساقعة؟ ده غاز الـ carbon dioxide متدوّب في مَيّة.","screen_text":"carbon dioxide CO₂ in water","pause_after_s":0.4},{"id":"s2l19","visual":"Particle picture (no written equation): one CO2 molecule meets a H2O molecule (YK.molecule) in the glass on cue 'المية' and the pair turns into an amber-glow cluster tagged 'acid' on cue 'acid'; word line 'non-metal oxide + water -> acid' (YK.formula 44, arrow gold) builds in the text panel on cues 'non' / 'المية' / 'acid'. No indicator colour.","tts_text":"والـ non-metal oxide في المية بيعمل acid، عشان كده طعمها بيقرص شوية.","screen_text":"non-metal oxide + water → acid","pause_after_s":0.4},{"id":"s2l20","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 380, {term: 'acidic oxide', def: 'A non-metal oxide that dissolves in water to give an acid.', keys: ['give an acid'], align: 'left', accent: C.amber, p: on cue 'acidic'}).","tts_text":"الـ non-metal oxide ده اسمه acidic oxide، بيدّي acid لما يدوب في المية.","screen_text":"acidic oxide: A non-metal oxide that dissolves in water to give an acid.","pause_after_s":0.8},{"id":"s2l21","visual":"Right column header 'non-metal oxides → acidic oxides' on cue 'non'; 'Most' (gold) on 'ومعظم'; YK.formula row 'CO2   SO3' (mono 56) with SO3 lighting on cue 'sulphur' (tag 'sulphur trioxide' 36).","tts_text":"ومعظم الـ non-metal oxides كده، زي الـ sulphur trioxide، بتبقى acidic oxides برضه.","screen_text":"Most non-metal oxides → acidic oxides: SO₃","pause_after_s":0.4},{"id":"s2l22","visual":"Both columns now full (basic left, acidic right); a sorting arrow: an O disc with a '?' partner in the centre (YK.atomDisc el 'O' + empty ring) on cue 'oxygen'; the ring tilts left on 'metal' (cyan glow on the basic column) then right on 'non' (amber glow on the acidic column). YK.fpara 'Metal or non-metal? Usually that is enough' (44) in the text panel.","tts_text":"بص على العنصر اللي مع الـ oxygen: metal ولا non-metal؟ وغالبًا ده يكفي.","screen_text":"Metal or non-metal? Usually that is enough","pause_after_s":1},{"id":"s3l2","visual":"Stage: a spoon of black powder above a YK.beaker labelled 'sulphuric acid' (tag 'dilute' 32 under it) on cue 'sulphuric'; label 'copper (II) oxide' + YK.formula 'CuO' (mono 56) over the spoon on cue 'copper'. The worked steps will stack in the text panel (YK.list, LTR).","tts_text":"عندنا copper two oxide، وهنحطه في sulphuric acid من النوع الـ dilute كده.","screen_text":"copper (II) oxide + dilute sulphuric acid","pause_after_s":0.4},{"id":"s3l2a","visual":"YK.flashRect around '(II)' in the s3l2 'copper (II) oxide' label on cue 'two' + YK.tag '(II): part of the name' (36, textDim) under it; stage unchanged.","tts_text":"الـ two اللي في الاسم ده جزء من الاسم، وهتفهم معناه في الفصل.","screen_text":"(II): part of the name","pause_after_s":0.4},{"id":"s3l3","visual":"Step 1 in YK.list (96, 300): 'copper → metal → basic oxide' builds on cues 'copper' / 'metal' / 'basic' (arrows gold via YK.formula '->'); the left 'basic oxides' column from s2 flashes briefly as a callback (YK.flashRect, small, top-right of the stage).","tts_text":"أول خطوة: الـ copper ده metal، يبقى ده basic oxide، زي ما قلنا.","screen_text":"First: copper is a metal → basic oxide","pause_after_s":0.4},{"id":"s3l4","visual":"Step 2: the powder drops in and shrinks (solid p 1 → 0) on cue 'acid'; bubbles stay 0; YK.list item 'salt + water, no gas' on cues 'salt' / 'غاز' + YK.rightMark small on 'غاز'.","tts_text":"يبقى الـ basic oxide مع الـ acid هيدّي salt ومَيّة، من غير غاز.","screen_text":"basic oxide + acid → salt + water · no gas","pause_after_s":0.4},{"id":"s3l5","visual":"Step 3 as a particle picture in an inset (same drawing as s2l8): H discs from the acid meet the O of CuO (YK.atomDisc el 'Cu' + 'O') and form YK.molecule H2O on cue 'المية'; tag 'water'.","tts_text":"الـ hydrogen بتاع الـ acid، مع الـ oxygen بتاع الـ oxide، يعملوا المية.","screen_text":"acid's hydrogen + oxide's oxygen → water","pause_after_s":0.4},{"id":"s3l6","visual":"Step 4: the Cu disc joins the amber leftover-acid dots (same salt cluster as s2l10) on cue 'يمسك'; label 'copper (II) sulphate' (44) on cue 'sulphate' with tag 'salt' on cue 'salt'.","tts_text":"والـ copper يمسك في باقي الـ acid، فيطلع salt اسمه copper two sulphate كده.","screen_text":"salt: copper (II) sulphate","pause_after_s":0.4},{"id":"s3l7","visual":"The one written equation of the video, book notation (lesson s2 formula; condition over the arrow as the book writes FeO + dil. acid, p.22): YK.formula(ctx, 'CuO + H2SO4 ->[dil.] CuSO4 + H2O', 1307, 560, {size: 72, align: 'center', reveal: from cue 'oxide' to cue 'ومية'}); brackets (YK.bracket) under 'CuO' on 'oxide', under 'H2SO4' on 'acid', under 'CuSO4' on 'salt', under 'H2O' on 'ومية'.","tts_text":"ودي المعادلة: الـ oxide مع الـ dilute acid، يدّوا salt ومَيّة.","screen_text":"CuO + H₂SO₄ →(dil.) CuSO₄ + H₂O","pause_after_s":1},{"id":"s3l8","visual":"Self-check on a NEW case (not the worked example): stage clears; a spoon of white magnesium oxide powder above a YK.beaker labelled 'hydrochloric acid' (tag 'dilute' 32) on cue 'magnesium'. YK.predictCard(ctx, t, {at: YK.cue('s3l8'), until: YK.cue('s3l10') + 0.4, think: YK.cueEnd('s3l9'), end: YK.cue('s3l10'), kind: 'QUICK CHECK', q: 'Magnesium oxide + dilute hydrochloric acid: gas or no gas? What forms?'}).","tts_text":"دورك: الـ magnesium oxide مع الـ hydrochloric acid الـ dilute كده.","screen_text":"Your turn: magnesium oxide + dilute hydrochloric acid","pause_after_s":0.4},{"id":"s3l9","visual":"The question stays; YK.checkPause(ctx, 1307, 860, {t, start: YK.cueEnd('s3l9'), dur: 4}) think ring + countdown through the silence; only the question shows (no answer, no hint) during the pause.","tts_text":"هيطلع غاز ولا لأ؟ وإيه اللي هيتكوّن؟ وقّف الفيديو وفكّر.","screen_text":"Gas or no gas? What forms?","pause_after_s":4},{"id":"s3l10","visual":"Answer: the powder drops and dissolves, bubbles stay 0, on cue 'الإجابة'; YK.answerSlot(ctx, t, {at: YK.cue('s3l10','غاز'), text: 'No gas', x: 420, y: 700}); reason line 'magnesium → metal → basic oxide' (YK.formula 44) builds on cues 'magnesium' / 'metal' / 'basic'.","tts_text":"الإجابة: مفيش غاز، عشان الـ magnesium metal، فده basic oxide زي ما شفنا.","screen_text":"No gas ✓ magnesium: metal → basic oxide","pause_after_s":0.4},{"id":"s3l11","visual":"Label 'magnesium chloride + water' (YK.fpara 48, mint) under the answer on cues 'magnesium' / 'مية'; tag 'salt' on cue 'salt'.","tts_text":"فيدّي salt اسمه magnesium chloride، ومعاه مَيّة.","screen_text":"magnesium chloride + water","pause_after_s":0.4},{"id":"s3l12","visual":"Reason as a particle picture (same inset drawing as s2l8 / s3l5, now with an Mg disc): H from the acid + O from MgO → YK.molecule H2O on cue 'oxygen'; tag 'water'; YK.rightMark on the inset.","tts_text":"والمية دي من الـ hydrogen بتاع الـ acid، والـ oxygen بتاع الـ oxide نفسه.","screen_text":"water: acid's hydrogen + oxide's oxygen","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, 'Iron(II) oxide FeO', {kind: 'concept', align: 'left'}) (map title_en exactly) on cue 'iron'; a black-powder swatch (book: black powder) beside it; tag 'basic oxide' (40, cyan) on cue 'basic'.","tts_text":"في الفصل هتقابل الـ iron two oxide، وده basic oxide برضه.","screen_text":"Iron(II) oxide FeO: basic oxide","pause_after_s":0.4},{"id":"s4l3","visual":"Word line (not a second equation): 'FeO + dilute acid -> iron (II) salt + water' (YK.formula 44) under the chip, parts lighting on cues 'dilute' / 'iron' / 'ومية' (book p.22: reacts with dilute mineral acids forming iron (II) salts and water).","tts_text":"مع الـ dilute acid بيدّي iron two salt ومَيّة، زي ما اتعلمنا.","screen_text":"FeO + dilute acid → iron (II) salt + water","pause_after_s":0.4},{"id":"s4l4","visual":"Second YK.chip(ctx, 820, 560, 'Iron(III) oxide Fe₂O₃', {kind: 'concept', align: 'left'}) on cue 'iron'; YK.tag 'basic oxide' (40, cyan) on cue 'basic'. No word line, no flask/heat glyph.","tts_text":"والـ iron three oxide كمان basic oxide، وشروط تفاعله هتعرفها في الفصل.","screen_text":"Iron(III) oxide Fe₂O₃: basic oxide","pause_after_s":0.8},{"id":"s4l5","visual":"Recap (s4l5–s4l7 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l5'), until: YK.cue('s4l7'), title: 'Acidic and basic oxides', line: 'Most metal oxides: basic oxides -> salt + water', pulse: [{word: 'basic', at: YK.cueX('s4l5','basic')}, {word: 'salt', at: YK.cueX('s4l5','salt')}]}); stage: the two-column board of s2 returns small, left column glowing.","tts_text":"الخلاصة: معظم الـ metal oxides تبقى basic oxides، ومع الـ acid تدّي salt ومَيّة.","screen_text":"Most metal oxides: basic oxides → salt + water","pause_after_s":0.4},{"id":"s4l6","visual":"Same recap card, second line 'Most non-metal oxides: acidic oxides -> acid in water' added under the first on cue 'non'; right column glows.","tts_text":"ومعظم الـ non-metal oxides تبقى acidic oxides، وتعمل acid لما تدوب في المية.","screen_text":"Most non-metal oxides: acidic oxides → acid in water","pause_after_s":0.6},{"id":"s4l7","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Acidic and basic oxides', line: 'Basic oxide + acid → salt + water.', t, pulse: [{word: 'Basic oxide', at: YK.cueX('s4l7','basic')}, {word: 'salt', at: YK.cueX('s4l7','salt')}, {word: 'water', at: YK.cueX('s4l7','ومية')}]}) held ≥ 2.5 s; no fade to black, no outro.","tts_text":"يعني basic oxide مع acid، يدّي salt ومَيّة.","screen_text":"Basic oxide + acid → salt + water.","pause_after_s":1.5}],"logline":"هتعرف تفرّق بين الـ basic oxide والـ acidic oxide من العنصر اللي مع الـ oxygen، وتتوقع إن الـ basic oxide مع الـ acid بيدّي salt ومية من غير غاز.","segments":[{"id":"s1","title":"A rusty nail, metals and acids","concept_id":"chem.oxides"},{"id":"s2","title":"Basic oxides and acidic oxides","concept_id":"chem.oxides"},{"id":"s3","title":"Copper two oxide in dilute sulphuric acid","concept_id":"chem.oxides"},{"id":"s4","title":"Where Chapter 1 uses 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على مسمار قديم من الـ iron سايبينه في\nالهوا الرطب شهور\nالطبقة الخشنة اللي عليه دي هي الصدا اللي\nنعرفه\nالصدا ده iron اتّحد مع الـ oxygen الغاز\nاللي بنتنفسه\nأي عنصر يتّحد مع الـ oxygen الناتج اسمه\noxide والصدا ده iron oxide كده\nالـ iron ده metal يعني لامع وبيوصّل\nالكهربا والحرارة\nوكمان الـ copper والـ magnesium نوعهم\nmetal زي الـ iron بالظبط\nالليمون والخل طعمهم حامض صح\nالحموضة دي جاية من مادة اسمها acid جواهم\nوفي المعمل فيه acids أقوى زي الـ\nhydrochloric acid والـ sulphuric acid كمان\nيبقى معانا تلات كلمات metal و oxide و acid\nخلّيهم في بالك\nالـ acid اللي هنستخدمه dilute يعني متخفف\nبمَيّة كتير\nحُط حتة iron في الـ hydrochloric acid\nتلاقيها بتفوّر وتطلّع hydrogen غاز خفيف\nطب الصدا يعني الـ iron oxide في الـ acid\nهيفوّر ويطلّع hydrogen فكّر\nلأ الـ iron oxide بيدوب في الـ acid من غير\nأي غاز\nفيه ناس فاكرة إن الـ iron oxide هيفوّر زي\nالـ iron وده غلط\nالـ iron هنا متّحد مع الـ oxygen مش metal\nحر لوحده\nالـ hydrogen بتاع الـ acid بيمسك في الـ\noxygen بتاع الـ oxide ويعمل مَيّة\nوباقي الحاجات بتتجمع في مادة اسمها salt مش\nشرط ملح الأكل\nالـ salt ده بيبقى فيه الـ metal وجزء من\nالـ acid برضه\nالـ metal oxide ده اسمه basic oxide مع الـ\nacid يدّي salt ومَيّة\nواسمه basic عشان بيتصرف زي الـ base عكس\nالـ acid وبيلغي حموضته\nومعظم الـ metal oxides زي الـ iron oxide\nبتبقى basic oxides برضه\nوخلّي بالك بنقول معظم الـ metal oxides\nبتبقى basic مش كلهم\nالـ aluminum oxide مثلًا بيتفاعل مع الـ\nacid ومع الـ base كمان\nوفيه عناصر تانية أغلبها مش لامع اسمها\nnon-metals كده\nزي الـ sulphur والـ carbon ودول من الـ\nnon-metals دي\nفاكر فقاقيع الحاجة الساقعة ده غاز الـ\ncarbon dioxide متدوّب في مَيّة\nوالـ non-metal oxide في المية بيعمل acid\nعشان كده طعمها بيقرص شوية\nالـ non-metal oxide ده اسمه acidic oxide\nبيدّي acid لما يدوب في المية\nومعظم الـ non-metal oxides كده زي الـ\nsulphur trioxide بتبقى acidic oxides برضه\nبص على العنصر اللي مع الـ oxygen metal ولا\nnon-metal وغالبًا ده يكفي\nعندنا copper two oxide وهنحطه في sulphuric\nacid من النوع الـ dilute كده\nالـ two اللي في الاسم ده جزء من الاسم\nوهتفهم معناه في الفصل\nأول خطوة الـ copper ده metal يبقى ده basic\noxide زي ما قلنا\nيبقى الـ basic oxide مع الـ acid هيدّي\nsalt ومَيّة من غير غاز\nالـ hydrogen بتاع الـ acid مع الـ oxygen\nبتاع الـ oxide يعملوا المية\nوالـ copper يمسك في باقي الـ acid فيطلع\nsalt اسمه copper two sulphate كده\nودي المعادلة الـ oxide مع الـ dilute acid\nيدّوا salt ومَيّة\nدورك الـ magnesium oxide مع الـ\nhydrochloric acid الـ dilute كده\nهيطلع غاز ولا لأ وإيه اللي هيتكوّن وقّف\nالفيديو وفكّر\nالإجابة مفيش غاز عشان الـ magnesium metal\nفده basic oxide زي ما شفنا\nفيدّي salt اسمه magnesium chloride ومعاه\nمَيّة\nوالمية دي من الـ hydrogen بتاع الـ acid\nوالـ oxygen بتاع الـ oxide نفسه\nطب الكلام ده هيفيدك فين في الفصل\nفي الفصل هتقابل الـ iron two oxide وده\nbasic oxide برضه\nمع الـ dilute acid بيدّي iron two salt\nومَيّة زي ما اتعلمنا\nوالـ iron three oxide كمان basic oxide\nوشروط تفاعله هتعرفها في الفصل\nالخلاصة معظم الـ metal oxides تبقى basic\noxides ومع الـ acid تدّي salt ومَيّة\nومعظم الـ non-metal oxides تبقى acidic\noxides وتعمل acid لما تدوب في المية\nيعني basic oxide مع acid يدّي salt ومَيّة","countable":false,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":85,"see_also":[{"item_id":"chem-s3-en.lesson-te.uses-v-cr","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Economic importance of vanadium and chromium","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":71.58,"kind":"pause_question","spec":{"answer":"لأ: الـ iron هنا متحد مع الـ oxygen، مش metal حر، فبيدوب من غير غاز.","prompt":"الـ iron oxide في الـ dilute acid: هيفوّر ويطلّع hydrogen؟","options":[{"id":"a","text":"لأ، بيدوب من غير غاز","correct":true},{"id":"b","text":"أيوه، زي الـ iron","correct":false}],"answer_t_s":75.46,"concept_id":"chem.oxides"},"content_lang":"ar-EG"},{"id":"think-2","t_s":218.64,"kind":"pause_question","spec":{"answer":"مفيش غاز: الـ magnesium metal، فده basic oxide، و basic oxide + acid → salt + water (magnesium chloride + water).","prompt":"magnesium oxide + dilute hydrochloric acid: هيطلع غاز؟ وإيه اللي هيتكوّن؟","options":[{"id":"a","text":"مفيش غاز: magnesium chloride + water","correct":true},{"id":"b","text":"hydrogen gas + magnesium chloride","correct":false},{"id":"c","text":"مفيش تفاعل","correct":false}],"answer_t_s":223.13,"concept_id":"chem.oxides"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.oxides"]},{"id":"chem-s3-en.video-walkthrough-chem.rusting-corrosion","kind":"walkthrough","version":6,"ord":94,"content_lang":"ar-EG","primary_concept_id":"chem.rusting-corrosion","concepts":[{"concept_id":"chem.rusting-corrosion","role":"primary"}],"title":"Rusting and corrosion: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.rusting-corrosion (hook: iron nail in a wet garden turns red-brown in weeks vs a gold ring for centuries; KeyTerm Corrosion verbatim; 'Rusting is the corrosion of iron', 'Rust: hydrated iron (III) oxide', 'Some metals corrode quickly, like iron; gold hardly at all'; experiment A dry air + drying agent closed / B boiled water under oil / C air and water, 'Only nail C rusts', 'oxygen and moisture together'; 'Rust is porous (full of tiny holes) and flakes off… rusting continues'; coatings flow 'Coating on the iron → Oxygen and moisture kept away → Rusting is slowed'; paint/oil/grease on bridges, car bodies, chains; Galvanizing 'Coating iron with a layer of zinc.'; Plating 'Covering iron with a thin layer of another metal that resists corrosion.'; check items gate with flaking rust (worked example) and oiled bicycle chain (self-check, with the layer's reason: barrier, does not remove rust or change the iron); recap 'scratch in the paint' (s2l29); next: chromium resists the air, keep 'porous' in mind). Concept chem.rusting-corrosion v2 has no recorded misconceptions: s2 refutes the lesson's 'water alone causes rust' (layer feedback B, s2l17–s2l18; plus 'oxygen alone is not enough', s2l19) and 'the rust layer protects the iron' (porous, s2l21–s2l23; prepares te.chromium-oxide-layer.mc2 'Any oxide layer protects a metal' without teaching it). Dependents named in s4: 'Why chromium resists the effect of atmosphere' (map title; uses 'porous'; its reason left to that lesson), the 'Economic importance' lessons (te.uses-cu-zn, te.uses-mn, te.uses-ni, te.uses-v-cr: resists corrosion / galvanizing / plating, book pp.6-8) named by the shared heading only, no uses or metals added. Terms at first use: s1 rust, oxygen, moisture; s2 metals, react (plain), rusting, hydrated / oxide / '(III)' glossed, corrosion, drying agent, porous, galvanizing, plating. s3/s4 add none. Voicing: «hydrated iron تلاتة oxide» per chem-s3-en.voice.groups-configs / voice.ions. Predicts: s2l15 (~1:50), s3l9–10 (~4:00). not-in-source: iron and gold are metals, shiny and conduct electricity (plain gloss); oxide = joined with oxygen, hydrated = has water in it (plain glosses); oxygen is the gas we breathe; moisture = water in the air (plain meaning); boiling drives the air out of water (lesson layer explanation, not lesson body); a scratched coating lets the bare iron rust (lesson recap answer; s2l29 is scoped to paint only). Estimated duration ≈ 300 s (≈ 5:00; 580 words at ~2.4 words/s + 42 s pauses + joins); planning aid only.","title":"Rusting and corrosion: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"YK.camera pushes in on the nail; YK.tag 'iron' (44) points to it on cue 'iron'; YK.drop ×3 (C.cyan, alpha 0.6) bead on the nail on cue 'مبلولة'.","tts_text":"بص على مسمار iron قديم، مرمي في جنينة مبلولة.","screen_text":"An iron nail in a wet garden","pause_after_s":0.4},{"id":"s1l3","visual":"A small calendar strip (page-local, pages flipping, no numbers) runs on cue 'أسبوع'; the nail surface tweens from C.steel to a red-brown crust (rust colour as the lesson describes, YK.mix) from cue 'لونه' to 'بني'; crust texture = YK.rock seeded patches clipped to the nail.","tts_text":"بعد كام أسبوع، لونه بيقلب أحمر بني كده.","screen_text":"Weeks later: red-brown","pause_after_s":0.4},{"id":"s1l4","visual":"YK.termCard(ctx, 96, 420, {term: 'rust', align: 'left'}) on cue 'rust'; YK.flashRect around the crust on the same cue.","tts_text":"الطبقة الحمرا البني دي اسمها rust، يعني الصدا.","screen_text":"rust","pause_after_s":0.4},{"id":"s1l5","visual":"Split stage: the rusty nail moves left (x 1000), a gold ring (ctx ring path, C.gold, shine sweep YK.glow) appears right (x 1600) on cue 'gold'; YK.tag 'gold' under it; a slow sparkle (YK.particles seed 7, count 8, mode 'float') on 'لامع'.","tts_text":"إنما خاتم الـ gold ممكن يفضل لامع مئات السنين.","screen_text":"A gold ring can last for centuries","pause_after_s":0.4},{"id":"s1l6","visual":"New picture: air around the nail as a field of small YK.atomDisc pairs (YK.molecule({formula: 'O2', r: 22}) ×8, seeded drift) on cue 'الهوا'; YK.termCard(ctx, 96, 420, {term: 'oxygen', align: 'left'}) + YK.fpara 'a gas in the air' (40) on cue 'oxygen'.","tts_text":"الهوا حوالينا فيه غاز اسمه oxygen، اللي بنتنفسه ده.","screen_text":"oxygen: a gas in the air","pause_after_s":0.4},{"id":"s1l7","visual":"Tiny water droplets (YK.drop, r 8, C.cyan, seeded drift) join the O2 molecules on cue 'moisture'; YK.termCard(ctx, 96, 560, {term: 'moisture', align: 'left'}) + YK.fpara 'water in the air' (40) on the same cue.","tts_text":"وفيه كمان moisture، يعني رطوبة: مَيّة موجودة في الهوا.","screen_text":"moisture: water in the air","pause_after_s":0.4},{"id":"s1l8","visual":"Micro-recap: three YK.chip kind 'concept' in the text panel (96, 300 / 420 / 540) on cues 'rust', 'oxygen', 'moisture'; the crust, an O2 molecule and a droplet on the stage flash (YK.flashRect) in the same order.","tts_text":"يبقى معانا تلات كلمات: rust و oxygen و moisture، خلّيهم في بالك.","screen_text":"rust · oxygen · moisture","pause_after_s":1},{"id":"s2l2","visual":"Two YK.cube pieces (iron C.steel, gold C.gold) slide in left → right on cues 'iron' / 'gold' with a shine sweep on 'لامعة'; a small circuit with YK.icon('lamp') lights through the iron cube on 'الكهربا'; a gold YK.bracket groups both with tag 'metals' on cue 'metals'.","tts_text":"الـ iron والـ gold من عيلة اسمها metals، لامعة وبتوصّل الكهربا.","screen_text":"metals: iron, gold","pause_after_s":0.4},{"id":"s2l3","visual":"Iron cube on the stage; on cue 'يتفاعل' an O2 molecule lands on it and the contact spot turns into a red-brown patch (new substance) on 'جديدة'; tag 'metal' on cue 'metal'; YK.fpara 'react: change into a new substance' (40) in the text panel.","tts_text":"والـ metal ممكن يتفاعل، يعني يتغير ويطلّع مادة جديدة.","screen_text":"react: change into a new substance","pause_after_s":0.4},{"id":"s2l4","visual":"Word line 'iron + oxygen + moisture -> rust' (YK.formula 48, arrow gold, LTR) builds on cues 'iron' / 'oxygen' / 'moisture'; YK.termCard(ctx, 96, 300, {term: 'rusting', align: 'left'}) on cue 'rusting'; stage: O2 molecules and droplets settle on the iron cube and a slow red-brown crust grows (YK.oxideSkin(ctx, 1300, 620, 700, 300, {metal: 'Fe', porous: true, p: from cue 'بالراحة' over 3 s, layerColor: rust red-brown, t})).","tts_text":"والـ rusting إن الـ iron يتفاعل بالراحة مع الـ oxygen والـ moisture سوا.","screen_text":"Rusting: iron + oxygen + moisture → rust","pause_after_s":0.4},{"id":"s2l5","visual":"Label 'Rust: hydrated iron (III) oxide' (lesson flow-diagram wording, YK.fpara 44) on the crust on cue 'hydrated'; the s1 rust term card flashes.","tts_text":"والـ rust ده اسمه في الكيميا hydrated iron three oxide كده.","screen_text":"rust: hydrated iron (III) oxide","pause_after_s":0.4},{"id":"s2l6","visual":"Zoom inset (YK.panel 1180, 200, 560, 360, YK.scaleBadge): YK.atomDisc el 'Fe' bonded to el 'O' on cue 'oxide'; a small YK.molecule({formula: 'H2O', r: 26}) tucked between them on cue 'hydrated'; tags 'oxide' / 'hydrated' on their cues.","tts_text":"الـ oxide يعني متّحد مع oxygen، والـ hydrated يعني فيه مَيّة.","screen_text":"oxide: joined with oxygen · hydrated: has water in it","pause_after_s":0.4},{"id":"s2l7","visual":"YK.flashRect around '(III)' in the s2l5 label on cue 'three' + YK.tag '(III): part of the name' (36, textDim) under it; stage unchanged.","tts_text":"والـ three اللي في الاسم جزء من الاسم، وهتفهمها في الفصل.","screen_text":"(III): part of the name","pause_after_s":0.4},{"id":"s2l8","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 340, {term: 'corrosion', def: 'The slow reaction of a metal with substances in the air, like oxygen and moisture, that wears the metal away.', keys: ['wears the metal away'], align: 'left'}) on cue 'corrosion'; stage: the iron cube's edge pits and thins (page-local erosion mask, seeded) on cue 'فيتآكل'.","tts_text":"الـ corrosion: metal بيتفاعل بالراحة مع الـ oxygen والـ moisture فيتآكل.","screen_text":"corrosion: The slow reaction of a metal with substances in the air, like oxygen and moisture, that wears the metal away.","pause_after_s":0.8},{"id":"s2l9","visual":"YK.fpara 'Rusting is the corrosion of iron' (48) under the card on cue 'rusting'; YK.bracket links the word 'corrosion' on the card to the rusty iron cube on cue 'iron'.","tts_text":"والـ rusting ده الـ corrosion بتاع الـ iron بالذات.","screen_text":"Rusting is the corrosion of iron","pause_after_s":0.4},{"id":"s2l10","visual":"Side by side: iron cube crust grows fast (YK.oxideSkin p 0.4 → 1) on cue 'بسرعة'; gold cube stays shiny on cue 'gold' with a small mint YK.rightMark-free glow (no stamp); tags 'iron' / 'gold'; YK.fpara 'Some metals corrode quickly, like iron; gold hardly at all' (40).","tts_text":"وفيه metals بتتآكل بسرعة زي الـ iron، والـ gold تقريبًا لأ.","screen_text":"Some metals corrode quickly, like iron; gold hardly at all","pause_after_s":0.4},{"id":"s2l11","visual":"New picture (lesson experiment, three tubes): YK.tube(ctx, 1000, 640, 150, 460) with a grey iron nail, white granules at the bottom (drying agent), stopper drawn on cue 'مقفولة'; label 'A' + YK.tag 'dry air' on cue 'ناشف', 'drying agent' on cue 'drying'.","tts_text":"تجربة: أنبوبة أولى مقفولة، فيها drying agent بيشرب الـ moisture، فهواها ناشف.","screen_text":"A: closed · drying agent: absorbs moisture → dry air","pause_after_s":0.4},{"id":"s2l12","visual":"Second YK.tube (x 1310) with a nail in water (level 0.65); a few bubbles leave the water and stop (YK.tube bubbles 0.6 → 0) on cue 'والغلي'; label 'B' + YK.tag 'boiled water' on cue 'مغلية'.","tts_text":"التانية فيها مَيّة مغلية، والغلي بيطلّع الهوا اللي فيها.","screen_text":"B: boiled water (the air driven out)","pause_after_s":0.4},{"id":"s2l13","visual":"A thin amber oil band forms on top of tube B's water on cue 'زيت'; O2 molecules approaching from above bounce off it (YK.flyer arcs reversing) on cue 'بتمنع'; YK.tag 'oil' beside the band.","tts_text":"وفوق المية طبَقة زيت، بتمنع الهوا يرجع تاني.","screen_text":"B: a layer of oil on top","pause_after_s":0.4},{"id":"s2l14","visual":"Third YK.tube (x 1620), open, a nail half in water (level 0.35), O2 molecules drifting in at the top on cue 'هوا'; label 'C' + YK.tag 'air and water' on cue 'ومية'.","tts_text":"والتالتة فيها هوا ومَيّة مع بعض، ومفتوحة.","screen_text":"C: air and water","pause_after_s":0.4},{"id":"s2l15","visual":"YK.predictCard(ctx, t, {at: YK.cueX('s2l15','بعد'), until: YK.cue('s2l16') + 0.4, think: YK.cueEnd('s2l15'), end: YK.cue('s2l16'), kind: 'PREDICT', q: 'After a week, which nail rusts: A, B or C?'}); the three tubes stay unchanged through the 3 s think ring; nothing is answered on screen during it.","tts_text":"بعد أسبوع، أنهي مسمار هيصدّي؟ فكّر قبل ما نكمّل.","screen_text":"PREDICT: after a week, which nail rusts?","pause_after_s":3},{"id":"s2l16","visual":"Answer: the nail in tube C turns red-brown (YK.mix, from cue 'صدّي') while A and B stay grey; YK.answerSlot(ctx, t, {at: YK.cueX('s2l16','التالتة'), text: 'Only nail C rusts', x: 420, y: 760}).","tts_text":"اللي صدّي هو مسمار التالتة لوحده، اللي فيها هوا ومَيّة.","screen_text":"Only nail C rusts","pause_after_s":0.6},{"id":"s2l17","visual":"Misconception: YK.mythLine(ctx, t, {at: YK.cue('s2l17'), wrongAt: YK.cueX('s2l17','غلط'), until: YK.cueEnd('s2l18') + 1.5, text: 'Water alone causes rust', x: 96, y: 300, size: 48}) — coral text with ✕ (YK.wrongMark) for its whole visible time; no strike-through.","tts_text":"فيه ناس فاكرة إن المية لوحدها بتعمل rust، وده غلط.","screen_text":"Water alone causes rust","pause_after_s":0.4},{"id":"s2l18","visual":"Fix (held ≥ the myth): tube B glows (YK.pulse); inside it no O2 molecules (the oil band holds them out) on cue 'oxygen'; its nail stays grey + YK.rightMark next to the fix line 'B: water, but no oxygen → no rust' (YK.fpara 44, mint, 96, 420) on cue 'rust'. The myth line keeps its ✕.","tts_text":"الأنبوبة التانية فيها مَيّة، إنما مفيهاش oxygen، فمطلعش rust هناك.","screen_text":"B: water, but no oxygen → no rust ✓","pause_after_s":0.4},{"id":"s2l19","visual":"Tube A glows; O2 molecules inside it on cue 'oxygen', the drying-agent granules absorb the last droplets (droplets shrink into them) on cue 'moisture'; its nail stays grey; YK.fpara 'A: oxygen, but no moisture → no rust' (44) under the fix line.","tts_text":"والأولى فيها oxygen، إنما مفيهاش moisture، فبرضه مطلعش rust هناك.","screen_text":"A: oxygen, but no moisture → no rust","pause_after_s":0.4},{"id":"s2l20","visual":"Tube C glows: an O2 molecule and a droplet meet on the nail surface on cue 'oxygen' / 'moisture' and the crust grows there; YK.fpara 'Rusting needs oxygen and moisture together' (48, gold keys 'oxygen and moisture together') on cue 'مع'.","tts_text":"يبقى الـ rusting محتاج الـ oxygen والـ moisture الاتنين مع بعض.","screen_text":"Rusting needs oxygen and moisture together","pause_after_s":0.8},{"id":"s2l21","visual":"Second misconception: YK.mythLine(ctx, t, {at: YK.cue('s2l21'), wrongAt: YK.cueX('s2l21','غلط'), until: YK.cueEnd('s2l23') + 1.5, text: 'The rust layer protects the iron', x: 96, y: 300, size: 44}) with ✕ for its whole visible time, no strike-through. Stage: zoom on the rusty nail's surface (YK.oxideSkin, porous: true, p 1).","tts_text":"وفيه ناس فاكرة إن طبَقة الـ rust بتحمي الـ iron تحتها، وده غلط.","screen_text":"The rust layer protects the iron","pause_after_s":0.4},{"id":"s2l22","visual":"YK.termCard(ctx, 96, 560, {term: 'porous', align: 'left'}) + YK.fpara 'full of tiny holes' (40) on cue 'porous'; the oxideSkin layer shows its gaps (porous: true) highlighted with small YK.pulse rings on 'خروم'.","tts_text":"الـ rust نفسه porous، يعني مليان خروم صغيرة جدًا.","screen_text":"porous: full of tiny holes","pause_after_s":0.4},{"id":"s2l23","visual":"Fix: crust pieces flake off (YK.shards on the layer, p from cue 'وبيقشّر'); O2 molecules and droplets pass through the gaps (YK.oxideSkin acid: 0 → 1 with particleColor C.cyan, acidLabel '') and pit the fresh metal on cue 'تحته'; YK.rightMark next to the fix line (YK.fpara 40, mint) on cue 'يكمّل'. The myth line keeps its ✕.","tts_text":"وبيقشّر ويقع، فالهوا والمية يوصلوا لحد الـ iron اللي تحته، والـ rusting يكمّل.","screen_text":"Rust flakes off → air and water reach fresh iron → rusting continues ✓","pause_after_s":0.6},{"id":"s2l24","visual":"New picture (lesson flow diagram): YK.flow 3 boxes LTR 'Coating on the iron' → 'Oxygen and moisture kept away' → 'Rusting is slowed' built on cues 'بنغطي' / 'تبعد' / 'نبطّأ'... (order of boxes fixed LTR, each lights on its cue); stage: a clean iron bar gets a coat sliding over it on 'بطبقة' and O2 molecules / droplets bounce off it on 'تبعد'.","tts_text":"عشان نبطّأ الـ rusting، بنغطي الـ iron بطبَقة تبعد الـ oxygen والـ moisture عنه.","screen_text":"Coating → oxygen and moisture kept away → rusting is slowed","pause_after_s":0.6},{"id":"s2l25","visual":"Three small icons in a row on the stage: YK.icon(ctx,'bridge') with a paint-coat swipe on cue 'الدهان', a car-body outline (page-local path) on 'العربيات', a chain drawn page-local with a glossy oil film on 'والجنازير'; tags 'paint', 'oil', 'grease' under them on cues 'الدهان' / 'والزيت' / 'والشحم'.","tts_text":"زي الدهان، والزيت، والشحم، على الكباري وجسم العربيات والجنازير.","screen_text":"Paint, oil, grease: bridges, car bodies, chains","pause_after_s":0.4},{"id":"s2l26","visual":"Definition card (lesson wording): YK.termCard(ctx, 96, 380, {term: 'galvanizing', def: 'Coating iron with a layer of zinc.', keys: ['zinc'], align: 'left'}) on cue 'galvanizing'; stage: a bucket outline (page-local) gets a silver-grey zinc layer sliding over it on cue 'zinc'; tags 'iron' / 'zinc' on their cues.","tts_text":"أو galvanizing، يعني نغطي الـ iron بطبَقة من الـ zinc كده.","screen_text":"galvanizing: Coating iron with a layer of zinc.","pause_after_s":0.6},{"id":"s2l27","visual":"Definition card (lesson wording): YK.termCard(ctx, 96, 380, {term: 'plating', def: 'Covering iron with a thin layer of another metal that resists corrosion.', keys: ['another metal'], align: 'left'}) on cue 'plating'; stage: an iron handle outline gets a thin shiny layer (C.text sheen) on cue 'رفيعة'; tags 'iron' on the handle on cue 'iron' and 'metal' on the layer on cue 'metal'.","tts_text":"أو plating: نغطي الـ iron بطبَقة رفيعة من metal تاني بيقاوم الـ corrosion كويس.","screen_text":"plating: Covering iron with a thin layer of another metal that resists corrosion.","pause_after_s":0.6},{"id":"s2l28","visual":"The four coated objects (bridge, chain, bucket, handle) in a row; O2 molecules and droplets bounce off each coat on cues 'oxygen' / 'moisture' (YK.flyer reversing arcs); YK.fpara 'Each coating keeps oxygen and moisture away from the iron' (40) in the text panel.","tts_text":"كل طبَقة من دول بتبعد الـ oxygen والـ moisture عن الـ iron نفسه.","screen_text":"Each coating keeps oxygen and moisture away from the iron","pause_after_s":0.4},{"id":"s2l29","visual":"A painted iron bar (the s2l25 bridge paint colour) gets a deep scratch line (page-local) on cue 'اتخدش'; bare grey iron shows in the line and a red-brown crust grows only there on cue 'rust'; tag 'iron' on the bare line on cue 'iron'; YK.fpara 'Paint scratched → bare iron → rust' (40). Galvanized bucket not used here.","tts_text":"ولو الدهان اتخدش، الـ iron اللي ظهر يطلع عليه rust تاني.","screen_text":"Paint scratched → bare iron → rust","pause_after_s":1},{"id":"s3l2","visual":"Stage: an iron gate (page-local bars, C.steel) in the s1 garden set, YK.rain light; red-brown flaking patches (YK.rock seeded) on its bars on cue 'rust'; tags 'iron' / 'rust' on their cues. Steps will stack in the text panel (YK.list, LTR, at = word cues).","tts_text":"عندنا بوابة iron قديمة في جنينة مبلولة، وعليها rust بيقشّر.","screen_text":"An old iron gate in a wet garden, with flaking rust","pause_after_s":0.4},{"id":"s3l3","visual":"YK.fpara 'Question: will it keep rusting?' (48) at the top of the text panel on cue 'السؤال'; the gate pulses once (YK.pulse) on 'البوابة'.","tts_text":"السؤال: البوابة دي هيكمّل فيها الـ rusting؟ يلا نحِلّها سوا.","screen_text":"Question: will it keep rusting?","pause_after_s":0.4},{"id":"s3l4","visual":"YK.list item 1 builds on cues 'rusting' / 'oxygen' / 'moisture'; the s2l20 rule line flashes small top-right (YK.flashRect) as a callback.","tts_text":"أول خطوة: الـ rusting محتاج الـ oxygen والـ moisture مع بعض.","screen_text":"Step 1: rusting needs oxygen and moisture together","pause_after_s":0.4},{"id":"s3l5","visual":"YK.list item 2: O2 molecules drift around the gate on cue 'oxygen' and droplets bead on its bars on cue 'moisture'; a small YK.rightMark after each word on its cue.","tts_text":"تاني خطوة: الجنينة فيها هوا، يعني oxygen، وفيها moisture من المية.","screen_text":"Step 2: wet garden → oxygen ✓ moisture ✓","pause_after_s":0.4},{"id":"s3l6","visual":"Zoom on a bar (YK.zoomThrough + YK.scaleBadge): YK.oxideSkin porous layer with gaps on cue 'porous'; flakes fall (YK.shards) on 'وبيقشّر'; YK.list item 3 on cue 'بيحمي'.","tts_text":"تالت خطوة: الـ rust ده porous وبيقشّر، فمش بيحمي الـ iron اللي تحته.","screen_text":"Step 3: rust is porous and flakes off → no protection","pause_after_s":0.4},{"id":"s3l7","visual":"Particles pass through the gaps and the crust grows deeper (oxideSkin acid 0 → 1) on cue 'يكمّل'; YK.answerSlot(ctx, t, {at: YK.cueX('s3l7','أيوه'), text: 'Yes, rusting continues', x: 420, y: 760}).","tts_text":"يبقى الإجابة: أيوه، الـ rusting هيكمّل، والـ rust يدخل لجوه.","screen_text":"Answer: yes, rusting continues","pause_after_s":0.4},{"id":"s3l8","visual":"The gate gets a paint coat sliding over its bars on cue 'تغطيه'; O2 molecules and droplets bounce off on 'تبعد'; YK.list item 4 'To slow it: a coating, like paint' (no claim beyond the lesson's coatings).","tts_text":"ولو عايز تبطّأ ده، تغطيه بطبَقة زي الدهان، عشان تبعد الهوا والمية.","screen_text":"To slow it: a coating, like paint","pause_after_s":1},{"id":"s3l9","visual":"Self-check on a NEW case (not the worked example): stage clears; a bicycle chain (page-local links) with a glossy oil film on cue 'متزيّت'. YK.predictCard(ctx, t, {at: YK.cue('s3l9'), until: YK.cue('s3l11') + 0.4, think: YK.cueEnd('s3l10'), end: YK.cue('s3l11'), kind: 'QUICK CHECK', q: 'A bicycle chain is kept oiled. Why does it rust slowly?'}).","tts_text":"دورك: جنزير عجلة متزيّت على طول، ليه بيطلع عليه rust بالراحة؟","screen_text":"Your turn: a bicycle chain is kept oiled. Why does it rust slowly?","pause_after_s":0.4},{"id":"s3l10","visual":"The question stays; YK.checkPause(ctx, 1307, 860, {t, start: YK.cueEnd('s3l10'), dur: 4}) think ring + countdown through the silence; only the question shows (no answer, no hint) during the pause.","tts_text":"الزيت عمل إيه بالظبط؟ وقّف الفيديو وفكّر شوية.","screen_text":"What does the oil do?","pause_after_s":4},{"id":"s3l11","visual":"Answer: O2 molecules and droplets bounce off the oil film (YK.flyer reversing arcs) on cues 'oxygen' / 'moisture'; YK.answerSlot(ctx, t, {at: YK.cueX('s3l11','الإجابة'), text: 'The oil keeps oxygen and moisture away from the iron', x: 420, y: 700}).","tts_text":"الإجابة: الزيت طبَقة بتبعد الـ oxygen والـ moisture عن الـ iron نفسه.","screen_text":"The oil keeps oxygen and moisture away from the iron ✓","pause_after_s":0.4},{"id":"s3l12","visual":"Reason line under the answer: YK.fpara 'Oil does not remove rust or change the iron' (40, textDim) on cue 'بيشيل'; a barrier glyph (thin amber band between the chain and the drifting molecules) pulses on 'حاجز'. No strike-through on this negated line.","tts_text":"الزيت مش بيشيل الـ rust، ولا بيغيّر الـ iron نفسه، هو حاجز.","screen_text":"Oil does not remove rust or change the iron","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, 'Why chromium resists the effect of atmosphere', {kind: 'concept', align: 'left'}) (map title_en exactly) on cue 'chromium'; small YK.tag 'atmosphere' beside it on cue 'atmosphere'.","tts_text":"أول درس: ليه الـ chromium بيقاوم تأثير الـ atmosphere، يعني الهوا الجوي.","screen_text":"Why chromium resists the effect of atmosphere","pause_after_s":0.4},{"id":"s4l3","visual":"The s2l22 'porous' term card returns small under the chip on cue 'porous' (callback); a '?' tag (textDim) on 'والسبب'. No chromium layer drawn (the reason is taught in that lesson).","tts_text":"هناك افتكر كلمة porous كويس، والسبب هتعرفه في الدرس.","screen_text":"Keep 'porous' in mind","pause_after_s":0.4},{"id":"s4l4","visual":"Second YK.chip(ctx, 820, 460, 'Economic importance', {kind: 'concept', align: 'left'}) on cue 'economic'; three small tags 'resists corrosion', 'galvanizing', 'plating' (40) pop under it on their cues (callbacks to the s2 cards; no new uses or metals named).","tts_text":"وفي دروس الـ economic importance، هتقابل الـ corrosion والـ galvanizing والـ plating تاني.","screen_text":"Economic importance: resists corrosion · galvanizing · plating","pause_after_s":0.8},{"id":"s4l5","visual":"Recap (s4l5–s4l7 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l5'), until: YK.cue('s4l7'), title: 'Rusting and corrosion', line: 'Rusting needs oxygen + moisture · rust is porous', pulse: [{word: 'oxygen', at: YK.cueX('s4l5','oxygen')}, {word: 'porous', at: YK.cueX('s4l5','porous')}]}); stage: the three tubes of s2 return small, tube C glowing.","tts_text":"الخلاصة: الـ rusting محتاج oxygen و moisture، والـ rust porous فبيكمّل.","screen_text":"Rusting needs oxygen + moisture · rust is porous","pause_after_s":0.4},{"id":"s4l6","visual":"Same recap card, second line 'Coatings keep oxygen and moisture away' (paint, galvanizing) added on cue 'galvanizing'; the coated bucket thumbnail glows.","tts_text":"والطبقات زي الدهان والـ galvanizing بتبعد الـ oxygen والـ moisture عنه.","screen_text":"Coatings keep oxygen and moisture away","pause_after_s":0.6},{"id":"s4l7","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Rusting and corrosion', line: 'Rusting needs oxygen and moisture together.', t, pulse: [{word: 'Rusting', at: YK.cueX('s4l7','rusting')}, {word: 'oxygen', at: YK.cueX('s4l7','oxygen')}, {word: 'moisture', at: YK.cueX('s4l7','moisture')}, {word: 'together.', at: YK.cueX('s4l7','بعض')}]}) held ≥ 2.5 s; no fade to black, no outro.","tts_text":"يعني الـ rusting محتاج oxygen و moisture مع بعض.","screen_text":"Rusting needs oxygen and moisture together.","pause_after_s":1.5}],"logline":"هتعرف الـ rusting محتاج إيه بالظبط، وليه الـ rust بيكمّل لجوه، وإزاي الطبقات زي الدهان والـ galvanizing بتحمي الـ iron.","segments":[{"id":"s1","title":"A rusty nail and a gold ring","concept_id":"chem.rusting-corrosion"},{"id":"s2","title":"What rusting needs, and how to slow it","concept_id":"chem.rusting-corrosion"},{"id":"s3","title":"Will the old gate keep rusting?","concept_id":"chem.rusting-corrosion"},{"id":"s4","title":"Where Chapter 1 uses 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على مسمار iron قديم مرمي في جنينة\nمبلولة\nبعد كام أسبوع لونه بيقلب أحمر بني كده\nالطبقة الحمرا البني دي اسمها rust يعني\nالصدا\nإنما خاتم الـ gold ممكن يفضل لامع مئات\nالسنين\nالهوا حوالينا فيه غاز اسمه oxygen اللي\nبنتنفسه ده\nوفيه كمان moisture يعني رطوبة مَيّة موجودة\nفي الهوا\nيبقى معانا تلات كلمات rust و oxygen و\nmoisture خلّيهم في بالك\nالـ iron والـ gold من عيلة اسمها metals\nلامعة وبتوصّل الكهربا\nوالـ metal ممكن يتفاعل يعني يتغير ويطلّع\nمادة جديدة\nوالـ rusting إن الـ iron يتفاعل بالراحة مع\nالـ oxygen والـ moisture سوا\nوالـ rust ده اسمه في الكيميا hydrated iron\nthree oxide كده\nالـ oxide يعني متّحد مع oxygen والـ\nhydrated يعني فيه مَيّة\nوالـ three اللي في الاسم جزء من الاسم\nوهتفهمها في الفصل\nالـ corrosion metal بيتفاعل بالراحة مع الـ\noxygen والـ moisture فيتآكل\nوالـ rusting ده الـ corrosion بتاع الـ\niron بالذات\nوفيه metals بتتآكل بسرعة زي الـ iron والـ\ngold تقريبًا لأ\nتجربة أنبوبة أولى مقفولة فيها drying agent\nبيشرب الـ moisture فهواها ناشف\nالتانية فيها مَيّة مغلية والغلي بيطلّع\nالهوا اللي فيها\nوفوق المية طبَقة زيت بتمنع الهوا يرجع تاني\nوالتالتة فيها هوا ومَيّة مع بعض ومفتوحة\nبعد أسبوع أنهي مسمار هيصدّي فكّر قبل ما\nنكمّل\nاللي صدّي هو مسمار التالتة لوحده اللي فيها\nهوا ومَيّة\nفيه ناس فاكرة إن المية لوحدها بتعمل rust\nوده غلط\nالأنبوبة التانية فيها مَيّة إنما مفيهاش\noxygen فمطلعش rust هناك\nوالأولى فيها oxygen إنما مفيهاش moisture\nفبرضه مطلعش rust هناك\nيبقى الـ rusting محتاج الـ oxygen والـ\nmoisture الاتنين مع بعض\nوفيه ناس فاكرة إن طبَقة الـ rust بتحمي الـ\niron تحتها وده غلط\nالـ rust نفسه porous يعني مليان خروم صغيرة\nجدًا\nوبيقشّر ويقع فالهوا والمية يوصلوا لحد الـ\niron اللي تحته والـ rusting يكمّل\nعشان نبطّأ الـ rusting بنغطي الـ iron\nبطبَقة تبعد الـ oxygen والـ moisture عنه\nزي الدهان والزيت والشحم على الكباري وجسم\nالعربيات والجنازير\nأو galvanizing يعني نغطي الـ iron بطبَقة\nمن الـ zinc كده\nأو plating نغطي الـ iron بطبَقة رفيعة من\nmetal تاني بيقاوم الـ corrosion كويس\nكل طبَقة من دول بتبعد الـ oxygen والـ\nmoisture عن الـ iron نفسه\nولو الدهان اتخدش الـ iron اللي ظهر يطلع\nعليه rust تاني\nعندنا بوابة iron قديمة في جنينة مبلولة\nوعليها rust بيقشّر\nالسؤال البوابة دي هيكمّل فيها الـ rusting\nيلا نحِلّها سوا\nأول خطوة الـ rusting محتاج الـ oxygen والـ\nmoisture مع بعض\nتاني خطوة الجنينة فيها هوا يعني oxygen\nوفيها moisture من المية\nتالت خطوة الـ rust ده porous وبيقشّر فمش\nبيحمي الـ iron اللي تحته\nيبقى الإجابة أيوه الـ rusting هيكمّل والـ\nrust يدخل لجوه\nولو عايز تبطّأ ده تغطيه بطبَقة زي الدهان\nعشان تبعد الهوا والمية\nدورك جنزير عجلة متزيّت على طول ليه بيطلع\nعليه rust بالراحة\nالزيت عمل إيه بالظبط وقّف الفيديو وفكّر\nشوية\nالإجابة الزيت طبَقة بتبعد الـ oxygen والـ\nmoisture عن الـ iron نفسه\nالزيت مش بيشيل الـ rust ولا بيغيّر الـ\niron نفسه هو حاجز\nطب الكلام ده هيفيدك فين في الفصل\nأول درس ليه الـ chromium بيقاوم تأثير الـ\natmosphere يعني الهوا الجوي\nهناك افتكر كلمة porous كويس والسبب هتعرفه\nفي الدرس\nوفي دروس الـ economic importance هتقابل\nالـ corrosion والـ galvanizing والـ\nplating تاني\nالخلاصة الـ rusting محتاج oxygen و\nmoisture والـ rust porous فبيكمّل\nوالطبقات زي الدهان والـ galvanizing بتبعد\nالـ oxygen والـ moisture عنه\nيعني الـ rusting محتاج oxygen و moisture\nمع بعض","countable":false,"session_id":"chem-s3-en.ch1.s2","session_no":2,"session_ord":86,"see_also":[{"item_id":"chem-s3-en.lesson-te.uses-v-cr","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Economic importance of vanadium and chromium","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":115.58,"kind":"pause_question","spec":{"answer":"C: الـ rusting محتاج oxygen و moisture مع بعض؛ B فيها مية من غير oxygen، و A فيها oxygen من غير moisture.","prompt":"بعد أسبوع، أنهي مسمار هيصدّي: A (هوا ناشف)، B (مية مغلية عليها زيت)، C (هوا ومية)؟","options":[{"id":"a","text":"C","correct":true},{"id":"b","text":"B و C، عشان فيهم مية","correct":false},{"id":"c","text":"A","correct":false}],"answer_t_s":119.34,"concept_id":"chem.rusting-corrosion"},"content_lang":"ar-EG"},{"id":"think-2","t_s":242.8,"kind":"pause_question","spec":{"answer":"الزيت طبقة (coating) بتبعد الـ oxygen والـ moisture عن الـ iron، فالـ rusting بيبطأ.","prompt":"جنزير العجلة المتزيّت: الزيت بيعمل إيه؟","options":[{"id":"a","text":"بيبعد الـ oxygen والـ moisture عن الـ iron","correct":true},{"id":"b","text":"بيشيل الـ rust اللي عليه","correct":false},{"id":"c","text":"بيغيّر الـ iron لمادة تانية","correct":false}],"answer_t_s":247.4,"concept_id":"chem.rusting-corrosion"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.rusting-corrosion"]},{"id":"chem-s3-en.video-walkthrough-chem.ions","kind":"walkthrough","version":4,"ord":174,"content_lang":"ar-EG","primary_concept_id":"chem.ions","concepts":[{"concept_id":"chem.ions","role":"primary"}],"title":"Ions (cations and anions): from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.ions (hook 'What does the 2+ mean?' + predict Fe2+ electrons; KeyTerms Ion, Cation, Anion verbatim on the definition cards; 'a neutral atom has equal numbers of protons (+) and electrons (−)'; 'only electrons move. The protons stay the same, so it is still the same element'; Na atom 11p/11e → loses 1 → Na+ 11p/10e; iron Z = 26 → Fe2+ 24 e, Fe3+ 23 e (layer: iron (II)/(III) ion); Cl 17p/17e gains 1 → Cl- 18 e; O 8p/8e gains 2 → O2- 10 e; recap 'Electrons in a cation = Z − charge'; checks Cu2+ (Z 29) → 27 (worked example here) and 25 protons / 23 electrons → Mn2+ (self-check here, with the layer's reason 'protons fix the element'); next: 'which electrons does iron lose first, 4s or 3d?'). Book p.9 (Fe2+, Fe3+ in the iron (II)/(III) exercise); book 'Chloride (Cl-)' for the anion name. Concept chem.ions v2 has no recorded misconceptions: s2 refutes the lesson's 'an ion is a different element' (s2l10–s2l12) and '2+ means 2 more electrons → 28' (layer feedback, s2l16–s2l19); s3l13 + s2l28 address 'electrons decide the element' (check feedback b). Dependents named in s4: 'Ions: 4s electrons are lost first' (map title; '4s' named only as 'part of the electron levels, the chapter explains it', no energy claim per chem-s3-en.ch1.guard.4s-removal) and 'Ionic and covalent bonds' (uses cation and anion; no bond taught); Fe2+/Fe3+ written by Chapter 1 (book_ref). Terms at first use: s1 atom, proton, electron (charge only in Arabic + signs there); s2 charge (positive/negative), neutral, element, ion, electric charge, cation, atomic number (Z), chloride ion, anion. s3 none; s4 names the two dependent titles (4s, ionic/covalent bonds) without teaching them. Voicing: ions by the book's names «الـ iron اتنين ion», «iron تلاتة ion», «copper اتنين ion», «manganese اتنين ion» (chem-s3-en.voice.ions; no 'two plus'); charges said as «اتنين موجب / اتنين سالب»; every spoken number appears on that line's screen (global.numbers.spoken-shown); ordinals 'أول/تاني/تالت/رابع خطوة' sit on 'Step 1–4' screens. Predicts: s2l16 (~2:05), s3l10–11 (~4:15). not-in-source: rubbing a balloon on hair moves electrons to the balloon, which becomes negative and attracts the hair (anchor; prereq phys.electric-charges); protons sit in the centre and electrons move around it (plain picture, prereq atom.energy-levels); element = one kind of atom (plain gloss); atomic number = number of protons (prereq atom.atomic-mass-number); sodium Z = 11, chlorine 17, oxygen 8 (lesson flow diagrams); '(II) in iron (II) ion = its charge 2+' (true for these simple ions). Estimated duration ≈ 325 s (≈ 5:25; ~630 words at ~2.4 words/s + 44 s pauses + joins); planning aid only.","title":"Ions (cations and anions): from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Stage: a glass of water (page-local drawing); on cue 'ملح' white salt grains fall into it, on cue 'وقلّبها' swirl lines and the grains dissolve. Text panel: HEAD 'Dissolve table salt in water'.","tts_text":"دوّب معلقة ملح طعام في كوباية مَيّة، وقلّبها كويس.","screen_text":"Dissolve table salt in water","pause_after_s":0.4},{"id":"s1l3","visual":"Two rods dip into the salt water; wires to a battery and a bulb draw on cue 'سِلكين'; the bulb lights up (gold glow) on cue 'نوّرت'. Text panel: para 'Salt water + battery: the bulb lights up'.","tts_text":"حط فيها سِلكين جايين من battery ولمبة، هتلاقي اللمبة نوّرت.","screen_text":"Salt water + battery: the bulb lights up","pause_after_s":0.4},{"id":"s1l4","visual":"The lit circuit stays on the stage; big + (coral) and − (cyan) signs in the text panel on cues 'موجبة' / 'وسالبة'.","tts_text":"السبب حاجات مشحونة جوه المية؛ والشحنات نوعين: موجبة وسالبة.","screen_text":"+ and −","pause_after_s":0.4},{"id":"s1l5","visual":"YK.zoomThrough from a hair strand to a grid of identical YK.atomDisc (r 34, el 'C', symbol false) with YK.scaleBadge on cue 'صغيرة'; YK.termCard(ctx, 96, 420, {term: 'atom', align: 'left'}) on cue 'atoms'.","tts_text":"وكل حاجة حوالينا مبنية من atoms، يعني حتت صغيرة جدًا.","screen_text":"atom · atoms","pause_after_s":0.4},{"id":"s1l6","visual":"One atom grows to fill the stage: a nucleus of small coral discs with '+' (YK.atomDisc color C.coral, label '+') appears at the centre on cue 'protons'; YK.termCard(ctx, 96, 420, {term: 'proton', align: 'left'}) + YK.fpara '+ , in the centre' (40) on the same cue.","tts_text":"جوه الـ atom فيه protons، شُحنتهم موجبة، قاعدين في النص.","screen_text":"proton: + , in the centre","pause_after_s":0.4},{"id":"s1l7","visual":"Small cyan dots with '−' orbit the nucleus (YK.atom(ctx, 1307, 600, {shells: [2, 4], nucleusLabel: '', rotate: t, size: 300}) with electron colour C.cyan) from cue 'electrons'; YK.termCard(ctx, 96, 560, {term: 'electron', align: 'left'}) + YK.fpara '− , around the centre' (40).","tts_text":"وحواليهم electrons صغيرة جدًا، شُحنتها سالبة، وبتتحرك حوالين النص.","screen_text":"electron: − , around the centre","pause_after_s":0.4},{"id":"s1l8","visual":"Back to the glass and the lit bulb: on cue 'بيتفكّك' small + (coral) and − (cyan) bits appear in the water and drift, + toward the rod on the battery's − side and − toward the other rod. Text panel: para 'In salt water, tiny charged bits carry the current'.","tts_text":"والملح جوه المية بيتفكّك لحتت صغيرة مشحونة، هي اللي بتوصّل الكهربا.","screen_text":"In salt water, tiny charged bits carry the current","pause_after_s":0.6},{"id":"s1l9","visual":"Micro-recap: three YK.chip kind 'concept' in the text panel (96, 300 / 420 / 540) on cues 'atom', 'proton', 'electron'; the atom drawing flashes (YK.flashRect) its nucleus on 'proton' and an electron on 'electron'.","tts_text":"يبقى معانا atom و proton و electron، وبيهم هنفهم الحتت المشحونة دي.","screen_text":"atom · proton · electron","pause_after_s":1},{"id":"s2l1a","visual":"Callback to the s1 balloon (small, top-right): its '−' badge pulses; YK.termCard(ctx, 96, 420, {term: 'charge', align: 'left'}) on cue 'charge' + YK.fpara 'positive (+) or negative (−)' (40) with '+' (C.coral) on cue 'positive' and '−' (C.cyan) on cue 'negative'.","tts_text":"والشحنة دي اسمها charge، يا positive يا negative كده.","screen_text":"charge: positive (+) or negative (−)","pause_after_s":0.4},{"id":"s2l2","visual":"A balance (YK.balance(ctx, 1307, 640, 600, {left: 'protons', right: 'electrons', value: 0})) levels on cue 'قد'; coral discs stack on the left pan on 'protons', cyan dots on the right on 'electrons'.","tts_text":"في الـ atom العادي، عدد الـ protons قدّ عدد الـ electrons بالظبط.","screen_text":"protons = electrons","pause_after_s":0.4},{"id":"s2l3","visual":"The balance stays level and glows mint on cue 'بتلغي'; YK.termCard(ctx, 96, 420, {term: 'neutral', align: 'left'}) + YK.fpara 'no overall charge' (40) on cue 'neutral'.","tts_text":"فالـ charges بتلغي بعض، ونقول عليه neutral، يعني متعادل.","screen_text":"neutral: no overall charge","pause_after_s":0.4},{"id":"s2l4","visual":"Stage: YK.atomDisc(ctx, 1307, 560, 120, {el: 'Na'}) on cue 'sodium'; three more identical Na discs fade in behind it on 'نوع'; YK.termCard(ctx, 96, 420, {term: 'element', align: 'left'}) + YK.fpara 'one kind of atom' (40) on cue 'element'.","tts_text":"الـ sodium ده element، يعني نوع معيّن من الـ atoms كده.","screen_text":"sodium: an element (one kind of atom)","pause_after_s":0.4},{"id":"s2l5","visual":"Na atom drawn with YK.atom(ctx, 1307, 600, {Z: 11, nucleusLabel: '11p', size: 320}) (shells 2, 8, 1); counters in the text panel (YK.formula mono 56): '11 p^+' on cue 'eleven'#1, '11 e^-' on cue 'eleven'#2; the balance thumbnail stays level.","tts_text":"مثلًا الـ sodium atom فيه eleven protons، و eleven electrons كمان.","screen_text":"Na atom: 11 protons, 11 electrons","pause_after_s":0.4},{"id":"s2l6","visual":"The outer electron of the Na atom pulses (YK.pulseA) on cue 'electron', then flies off up-right with a trail (YK.flyer, style-global: lost electrons fly off with a trail) on cue 'خسر'... timed to land off-stage by 'إيه'.","tts_text":"لو الـ sodium atom خِسِر one electron، يحصل إيه؟","screen_text":"Na loses 1 electron","pause_after_s":0.4},{"id":"s2l7","visual":"Counters: '11 p^+' stays (mint lock flash) on cue 'eleven'; electron counter tweens 11 → 10 (YK.counter) on cue 'ten'; the balance tips to the protons side on 'أكتر' (value −0.3); a '+' badge appears on the atom.","tts_text":"يفضل eleven protons، و ten electrons، يعني الموجب بقى أكتر.","screen_text":"11 protons, 10 electrons → one extra +","pause_after_s":0.4},{"id":"s2l8","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 340, {term: 'ion', def: 'An atom, or a group of atoms, that carries an electric charge because it lost or gained electrons.', keys: ['lost or gained electrons'], align: 'left'}) on cue 'ion'; stage keeps the Na atom with its '+' badge.","tts_text":"الـ ion: atom أو مجموعة atoms، خِسرت أو كِسبت electrons، وعليها electric charge كده.","screen_text":"ion: An atom, or a group of atoms, that carries an electric charge because it lost or gained electrons.","pause_after_s":0.8},{"id":"s2l9","visual":"YK.formula(ctx, 'Na^+', 1307, 300, {size: 120, align: 'center'}) above the atom on cue 'بالرمز'; YK.tag 'sodium ion' (44) under it on cue 'sodium'; the '+' in the formula pulses gold on 'موجب'.","tts_text":"ودي بنكتبها بالرمز ده، ونسميها sodium ion موجب.","screen_text":"Na⁺: sodium ion","pause_after_s":0.4},{"id":"s2l10","visual":"Misconception: YK.mythLine(ctx, t, {at: YK.cue('s2l10'), wrongAt: YK.cueX('s2l10','غلط'), until: YK.cueEnd('s2l12') + 1.5, text: 'An ion is a different element', x: 96, y: 300, size: 48}) — coral text with ✕ (YK.wrongMark) for its whole visible time; no strike-through.","tts_text":"فيه ناس فاكرة إن الـ ion بقى element تاني، وده غلط.","screen_text":"An ion is a different element","pause_after_s":0.4},{"id":"s2l11","visual":"Fix (held ≥ the myth): the nucleus of the Na⁺ drawing gets a mint lock outline (YK.bracket round, C.mint) on cue 'protons'; the flown electron's trail replays faintly on 'اتحركت'; YK.fpara 'Only electrons move · protons stay the same' (44, mint) + YK.rightMark on cue 'ثابتة'. The myth line keeps its ✕.","tts_text":"خد بالك: الـ protons ثابتة، والـ electrons هي اللي اتحركت لوحدها.","screen_text":"Only electrons move · protons stay the same ✓","pause_after_s":0.4},{"id":"s2l12","visual":"Na atom and Na⁺ ion side by side (two small YK.atom drawings, Z 11, the ion missing its outer electron), the same '11p' nucleus label in both highlighted on cue 'protons'; YK.tag 'same element' (40, mint) bridging them on cue 'element' + YK.rightMark.","tts_text":"وعشان الـ protons ثابتة، لسه نفس الـ element، يعني نفس نوع الـ atom بالظبط.","screen_text":"same protons → same element ✓","pause_after_s":0.6},{"id":"s2l13","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 340, {term: 'cation', def: 'A positive ion. Its charge equals the number of electrons the atom lost.', keys: ['electrons the atom lost'], align: 'left', accent: C.coral}) on cue 'cation'; stage: the Na⁺ formula gets YK.tag 'cation' on the same cue.","tts_text":"الـ cation ده positive ion، والـ charge قدّ الـ electrons اللي الـ atom خِسِرها.","screen_text":"cation: A positive ion. Its charge equals the number of electrons the atom lost.","pause_after_s":0.8},{"id":"s2l14","visual":"New picture: YK.elementCard-style tile (YK.panel + YK.formula) 'Fe' with '26' top-left on cue 'iron'; YK.termCard(ctx, 96, 420, {term: 'atomic number (Z)', align: 'left'}) + YK.fpara '= number of protons' (40) on cue 'atomic'; '26' pulses on 'twenty-six'.","tts_text":"الـ atomic number بتاع الـ iron twenty-six، يعني عدد الـ protons فيه.","screen_text":"atomic number (Z) = number of protons · Fe: 26","pause_after_s":0.4},{"id":"s2l15","visual":"Fe atom drawn with YK.atom(ctx, 1307, 600, {Z: 26, nucleusLabel: '26p', size: 330}); counters '26 p^+' and '26 e^-' (YK.formula mono 56) on cues 'twenty-six'#1 / 'twenty-six#1'; balance thumbnail level.","tts_text":"يعني الـ iron atom فيه twenty-six protons، و twenty-six electrons برضه.","screen_text":"Fe atom: 26 protons, 26 electrons","pause_after_s":0.4},{"id":"s2l16","visual":"YK.predictCard(ctx, t, {at: YK.cueX('s2l16','طب'), until: YK.cue('s2l17') + 0.4, think: YK.cueEnd('s2l16'), end: YK.cue('s2l17'), kind: 'PREDICT', q: 'Fe^2+ (charge 2+). How many electrons?'}); stage: YK.formula 'Fe^2+' (mono 120) over the atom on cue 'two'. Nothing is answered during the 3 s think ring.","tts_text":"طب لو الـ charge بقت two plus، يبقى فيه كام electron؟ فكّر.","screen_text":"PREDICT: Fe²⁺ (charge 2+). How many electrons?","pause_after_s":3},{"id":"s2l17","visual":"Misconception: YK.mythLine(ctx, t, {at: YK.cue('s2l17'), wrongAt: YK.cueX('s2l17','غلط'), until: YK.cueEnd('s2l18') + 1.5, text: '2+ → 2 more electrons → 28?', x: 96, y: 300, size: 48}) with ✕ (YK.wrongMark) for its whole visible time; two ghost electrons flying IN are drawn faint and crossed by YK.wrongMark(ctx, 1600, 420, 110) on the same cue.","tts_text":"فيه ناس بتقول twenty-eight، كأنه كِسِب two electrons، وده غلط.","screen_text":"2+ → 2 more electrons → 28?","pause_after_s":0.4},{"id":"s2l18","visual":"Fix (held ≥ the myth): two electrons fly OFF the Fe atom with trails (YK.flyer) on cue 'خسر'; each carries a '−' badge on 'سالبة'; YK.fpara '+ means electrons were lost (electrons are −)' (44, mint) + YK.rightMark on cue 'خسر'. The myth line keeps its ✕.","tts_text":"الموجب معناه إنه خِسِر electrons، مش كِسِب، لأن الـ electrons سالبة.","screen_text":"+ means electrons were lost ✓ (electrons are −)","pause_after_s":0.4},{"id":"s2l19","visual":"Answer: YK.formula '26 − 2 = 24' (mono 64) builds on cues 'twenty-six' / 'two' / 'twenty-four'; electron counter tweens 26 → 24 (YK.counter); YK.answerSlot(ctx, t, {at: YK.cueX('s2l19','twenty-four'), text: '24 electrons', x: 420, y: 760}).","tts_text":"يبقى twenty-six minus two equals twenty-four electrons كده.","screen_text":"26 − 2 = 24 electrons","pause_after_s":0.4},{"id":"s2l20","visual":"YK.tag 'iron (II) ion' (44) under 'Fe^2+' on cue 'iron'; YK.flashRect around '(II)' and '2+' together on cue 'two'#2 (the (II) in the name = the charge here); nucleus still '26p' (mint lock).","tts_text":"وده اسمه الـ iron two ion، وشُحنته two plus، يعني موجبة.","screen_text":"Fe²⁺: iron (II) ion, 2+","pause_after_s":0.4},{"id":"s2l21","visual":"A third electron flies off on cue 'خسر'; counter 24 → 23 on 'twenty-three'; formula updates to 'Fe^3+' with YK.tag 'iron (III) ion' on cue 'iron'. Old label removed when the identity changes (no label stays on a changed object).","tts_text":"ولو خِسِر three electrons، يفضل twenty-three، ويبقى iron three ion كده.","screen_text":"Fe³⁺: 3 lost → 23 electrons · iron (III) ion, 3+","pause_after_s":0.6},{"id":"s2l22","visual":"New picture: two YK.atomDisc (el 'Cl', el 'O', r 90) slide in left → right on cues 'chlorine' / 'oxygen'; a cyan dot flies IN to each on 'بتكسب'.","tts_text":"وفيه atoms تانية بتكسب electrons، زي الـ chlorine والـ oxygen كده.","screen_text":"Cl (chlorine) and O (oxygen) can gain electrons","pause_after_s":0.4},{"id":"s2l23","visual":"Cl atom (YK.atom Z 17, nucleusLabel '17p'); counters '17 p^+', '17 e^-' on cues 'seventeen'#1 / 'seventeen#1'; one electron flies IN (YK.flyer) on 'كسب'; electron counter 17 → 18 on 'eighteen'.","tts_text":"الـ chlorine فيه seventeen protons و seventeen electrons، ولو كِسِب one يبقوا eighteen كلهم.","screen_text":"Cl: 17 protons, 17 electrons · gains 1 → 18 electrons","pause_after_s":0.4},{"id":"s2l24","visual":"Balance tips to the electrons side on 'أكتر'; YK.formula 'Cl^-' (mono 120) above the atom on cue 'chloride'; YK.tag 'chloride ion' (44) under it on the same cue.","tts_text":"فالسالب بقى أكتر، وده اسمه الـ chloride ion السالب.","screen_text":"Cl⁻: chloride ion, −","pause_after_s":0.4},{"id":"s2l25","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 340, {term: 'anion', def: 'A negative ion. Its charge equals the number of electrons the atom gained.', keys: ['electrons the atom gained'], align: 'left', accent: C.cyan}) on cue 'anion'; YK.tag 'anion' on the Cl⁻ formula on the same cue.","tts_text":"الـ anion ده negative ion، والـ charge قدّ الـ electrons اللي الـ atom كِسِبها.","screen_text":"anion: A negative ion. Its charge equals the number of electrons the atom gained.","pause_after_s":0.8},{"id":"s2l26","visual":"O atom (YK.atom Z 8, nucleusLabel '8p'); two electrons fly IN on cue 'بيكسب'; counter 8 → 10 on 'ten'; YK.formula 'O^2-' (mono 100) + YK.tag 'anion' on 'minus'.","tts_text":"والـ oxygen، eight protons، بيكسب two، فيبقى ten electrons وشُحنته two minus، يعني سالبة.","screen_text":"O: 8 protons, 8 electrons · gains 2 → 10 electrons · O²⁻ (2−)","pause_after_s":0.4},{"id":"s2l27","visual":"Two-column board (YK.panel, cation coral left / anion cyan right): 'Na^+ · Fe^2+ · Fe^3+' under 'cation (+)' on cue 'cation'; 'Cl^- · O^2-' under 'anion (−)' on cue 'anion'; arrows 'lose' / 'gain' (YK.formula '->') on cues 'يخسر' / 'يكسب'.","tts_text":"يعني اللي يِخسر electrons يبقى cation، واللي يِكسب يبقى anion سالب.","screen_text":"lose electrons → cation (+) · gain electrons → anion (−)","pause_after_s":0.6},{"id":"s2l28","visual":"Board stays; under it YK.fpara 'Protons decide the element; electrons decide the charge' (44, gold keys) on cues 'protons' / 'electrons'.","tts_text":"الـ protons بتحدد الـ element، والـ electrons بتحدد الـ charge كده.","screen_text":"Protons decide the element; electrons decide the charge","pause_after_s":1},{"id":"s3l2","visual":"Stage: element tile 'Cu' with '29' top-left (YK.panel + YK.formula) on cue 'copper'; '29' pulses on 'twenty-nine'. Steps will stack in the text panel (YK.list, LTR, at = word cues).","tts_text":"عندنا الـ copper، والـ atomic number بتاعه twenty-nine كمان.","screen_text":"copper: atomic number 29","pause_after_s":0.4},{"id":"s3l3","visual":"YK.formula 'Cu^2+' (mono 120) beside the tile on cue 'copper'; YK.tag 'copper (II) ion' under it; a '?' electron counter (YK.formula '? e^-', mono 56) on 'كام'.","tts_text":"عايزين نعرف الـ copper two ion فيه كام electron بالظبط.","screen_text":"Cu²⁺: copper (II) ion, 2+ · how many electrons?","pause_after_s":0.4},{"id":"s3l4","visual":"YK.list item 1 'Step 1: protons = 29 (the atomic number)' on cue 'protons'; nucleus drawn YK.atom(ctx, 1307, 640, {Z: 29, nucleusLabel: '29p', size: 300, reveal: 0}) with only the nucleus visible, '29p' on 'twenty-nine'.","tts_text":"أول خطوة: الـ protons twenty-nine، زي الـ atomic number بالظبط.","screen_text":"Step 1: protons = 29 (the atomic number)","pause_after_s":0.4},{"id":"s3l5","visual":"YK.list item 2; the shells of the Cu atom reveal outward (reveal 0 → 1) on cue 'neutral'; counter '29 e^-' on 'twenty-nine'.","tts_text":"تاني خطوة: الـ atom الـ neutral فيه twenty-nine electrons برضه.","screen_text":"Step 2: neutral atom → 29 electrons","pause_after_s":0.4},{"id":"s3l6","visual":"YK.list item 3; two outer electrons fly off with trails (YK.flyer) on cue 'خسر'; the '2+' in 'Cu^2+' pulses gold on 'plus'.","tts_text":"تالت خطوة: الـ charge two plus، يعني خِسِر two electrons كده.","screen_text":"Step 3: charge 2+ → lost 2 electrons","pause_after_s":0.4},{"id":"s3l7","visual":"YK.list item 4 with YK.formula '29 − 2 = 27' building on cues 'twenty-nine' / 'two' / 'twenty-seven'; counter tweens 29 → 27 (YK.counter).","tts_text":"رابع خطوة: twenty-nine minus two equals twenty-seven electrons كده.","screen_text":"Step 4: 29 − 2 = 27 electrons","pause_after_s":0.4},{"id":"s3l8","visual":"Result tile: 'Cu^2+' with '29 p^+' (mint lock) and '27 e^-' (YK.formula mono 56) on cues 'twenty-nine' / 'twenty-seven'; YK.tag 'still copper' (40, mint) on 'ولسه' + YK.rightMark.","tts_text":"يعني الـ copper two ion: twenty-nine protons، و twenty-seven electrons، ولسه copper نفسه.","screen_text":"copper (II) ion, Cu²⁺ (2+): 29 protons, 27 electrons · still copper","pause_after_s":0.6},{"id":"s3l9","visual":"Rule card in the text panel (YK.panel, gold accent): YK.fpara 'Electrons in a cation = atomic number − charge' (48) on cue 'القاعدة'; 'atomic number' and 'charge' keys pulse on their cues.","tts_text":"القاعدة: electrons الـ cation هي الـ atomic number minus الـ charge بتاعته.","screen_text":"Electrons in a cation = atomic number − charge","pause_after_s":1},{"id":"s3l10","visual":"Self-check on a NEW case (not the worked example): stage clears; a mystery disc (YK.atomDisc el '?', r 110, C.violet) with counters '25 p^+' and '23 e^-' (YK.formula mono 56) on cues 'twenty-five'#1 / 'twenty-three'; a small element tile 'Mn 25' on cue 'manganese'. YK.predictCard(ctx, t, {at: YK.cue('s3l10'), until: YK.cue('s3l12') + 0.4, think: YK.cueEnd('s3l11'), end: YK.cue('s3l12'), kind: 'QUICK CHECK', q: '25 protons, 23 electrons. Which element? Atom, cation or anion? Charge?'}).","tts_text":"دورك: twenty-five protons و twenty-three electrons، والـ manganese فيه twenty-five برضه.","screen_text":"Your turn: 25 protons, 23 electrons · manganese has 25 protons","pause_after_s":0.4},{"id":"s3l11","visual":"The question stays; YK.checkPause(ctx, 1307, 860, {t, start: YK.cueEnd('s3l11'), dur: 4}) think ring + countdown through the silence; only the question shows (no answer, no hint) during the pause.","tts_text":"أنهي element؟ atom ولا cation ولا anion؟ والـ charge كام؟ وقّف وفكّر.","screen_text":"Which element? Atom, cation or anion? What charge?","pause_after_s":4},{"id":"s3l12","visual":"Answer: the '?' disc becomes YK.atomDisc el 'Mn' on cue 'manganese' (old '?' label removed); YK.answerSlot(ctx, t, {at: YK.cueX('s3l12','cation'), text: 'manganese · cation · 2+', x: 420, y: 700}).","tts_text":"الإجابة: ده manganese، وهو cation شُحنته two plus، يعني موجبة.","screen_text":"manganese · cation · 2+","pause_after_s":0.4},{"id":"s3l13","visual":"Reason lines under the answer (YK.list): '25 protons → manganese' on cue 'protons' (mint lock on '25 p^+'), '25 − 23 = 2 electrons lost → Mn^2+' on cues 'two' / 'ion'; YK.rightMark.","tts_text":"الـ protons بتحدد العنصر، وخِسِر two electrons، فبقى الـ manganese two ion كده.","screen_text":"25 protons → manganese · 25 − 23 = 2 electrons lost → Mn²⁺","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.formula 'Fe^2+' and 'Fe^3+' (mono 96) side by side on cues 'two' / 'three', tags 'iron (II)' / 'iron (III)' under them (callback to s2l20–s2l21); a mint YK.rightMark on 'فاهمهم'.","tts_text":"الفصل بيكتب الـ iron two والـ iron three كتير، وإنت دلوقتي فاهمهم.","screen_text":"Fe²⁺ (2+) · Fe³⁺ (3+): iron (II), iron (III)","pause_after_s":0.4},{"id":"s4l3","visual":"YK.chip(ctx, 820, 460, 'Ions: 4s electrons are lost first', {kind: 'concept', align: 'left'}) (map title_en exactly) on cue 'ions'; the 'electrons fly off' trail of s2l18 replays small beside it on 'بتطلع'.","tts_text":"في درس: الـ ions، وإن الـ electrons بتاعة الـ four s بتطلع الأول.","screen_text":"Ions: 4s electrons are lost first","pause_after_s":0.4},{"id":"s4l4","visual":"Small YK.tag '4s' (40) on cue 'four'; a faint shell ring of the s1 atom drawing highlights (YK.atom highlightShell) on 'مستويات'; YK.fpara 'the chapter explains it' (36, textDim). Nothing about energy order is shown or said.","tts_text":"الـ four s ده جزء من مستويات الـ electrons، والفصل هيشرحه.","screen_text":"4s: part of the electron levels · the chapter explains it","pause_after_s":0.4},{"id":"s4l5","visual":"Second YK.chip(ctx, 820, 700, 'Ionic and covalent bonds', {kind: 'concept', align: 'left'}) on cue 'ionic'; small tags 'cation' (coral) and 'anion' (cyan) beside it on their cues. No bond drawn (taught in that lesson).","tts_text":"وكمان درس الـ ionic والـ covalent bonds هيستخدم الـ cation والـ anion دول.","screen_text":"Ionic and covalent bonds","pause_after_s":0.8},{"id":"s4l6","visual":"Recap (s4l6–s4l8 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l6'), until: YK.cue('s4l8'), title: 'Ions (cations and anions)', line: 'lose electrons -> cation (+) · gain electrons -> anion (−)', pulse: [{word: 'cation', at: YK.cueX('s4l6','cation')}, {word: 'anion', at: YK.cueX('s4l6','anion')}]}); stage: the s2 board returns small.","tts_text":"الخلاصة: الـ atom لما يِخسر electrons يبقى cation، ولما يِكسب يبقى anion سالب.","screen_text":"lose electrons → cation (+) · gain electrons → anion (−)","pause_after_s":0.4},{"id":"s4l7","visual":"Same recap card, second line 'Protons stay the same · electrons in a cation = atomic number − charge' added on cue 'protons'.","tts_text":"والـ protons ثابتة، و electrons الـ cation هي الـ atomic number minus الـ charge بتاعته.","screen_text":"Protons stay the same · electrons in a cation = atomic number − charge","pause_after_s":0.6},{"id":"s4l8","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Ions (cations and anions)', line: 'Lose electrons → cation; gain electrons → anion.', t, pulse: [{word: 'cation;', at: YK.cueX('s4l8','cation')}, {word: 'anion.', at: YK.cueX('s4l8','anion')}]}) held ≥ 2.5 s; no fade to black, no outro.","tts_text":"يعني تِخسر electrons تبقى cation، تِكسب electrons تبقى anion كده.","screen_text":"Lose electrons → cation; gain electrons → anion.","pause_after_s":1.5}],"logline":"هتفهم إزاي الـ atom يبقى cation أو anion لما يخسر أو يكسب electrons، وتحسب عدد الـ electrons في ion زي الـ iron اتنين.","segments":[{"id":"s1","title":"Salt water lights a bulb","concept_id":"chem.ions"},{"id":"s2","title":"How an atom becomes an ion","concept_id":"chem.ions"},{"id":"s3","title":"Counting the electrons of an ion","concept_id":"chem.ions"},{"id":"s4","title":"Where Chapter 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معلقة ملح طعام في كوباية مَيّة\nوقلّبها كويس\nحط فيها سِلكين جايين من battery ولمبة\nهتلاقي اللمبة نوّرت\nالسبب حاجات مشحونة جوه المية والشحنات\nنوعين موجبة وسالبة\nوكل حاجة حوالينا مبنية من atoms يعني حتت\nصغيرة جدًا\nجوه الـ atom فيه protons شُحنتهم موجبة\nقاعدين في النص\nوحواليهم electrons صغيرة جدًا شُحنتها\nسالبة وبتتحرك حوالين النص\nوالملح جوه المية بيتفكّك لحتت صغيرة مشحونة\nهي اللي بتوصّل الكهربا\nيبقى معانا atom و proton و electron وبيهم\nهنفهم الحتت المشحونة دي\nوالشحنة دي اسمها charge يا positive يا\nnegative كده\nفي الـ atom العادي عدد الـ protons قد عدد\nالـ electrons بالظبط\nفالـ charges بتلغي بعض ونقول عليه neutral\nيعني متعادل\nالـ sodium ده element يعني نوع معيّن من\nالـ atoms كده\nمثلًا الـ sodium atom فيه eleven protons و\neleven electrons كمان\nلو الـ sodium atom خِسِر one electron يحصل\nإيه\nيفضل eleven protons و ten electrons يعني\nالموجب بقى أكتر\nالـ ion atom أو مجموعة atoms خِسرت أو\nكِسبت electrons وعليها electric charge كده\nودي بنكتبها بالرمز ده ونسميها sodium ion\nموجب\nفيه ناس فاكرة إن الـ ion بقى element تاني\nوده غلط\nخد بالك الـ protons ثابتة والـ electrons\nهي اللي اتحركت لوحدها\nوعشان الـ protons ثابتة لسه نفس الـ\nelement يعني نفس نوع الـ atom بالظبط\nالـ cation ده positive ion والـ charge قد\nالـ electrons اللي الـ atom خِسِرها\nالـ atomic number بتاع الـ iron twenty-six\nيعني عدد الـ protons فيه\nيعني الـ iron atom فيه twenty-six protons\nو twenty-six electrons برضه\nطب لو الـ charge بقت two plus يبقى فيه كام\nelectron فكّر\nفيه ناس بتقول twenty-eight كأنه كِسِب two\nelectrons وده غلط\nالموجب معناه إنه خِسِر electrons مش كِسِب\nلأن الـ electrons سالبة\nيبقى twenty-six minus two equals\ntwenty-four electrons كده\nوده اسمه الـ iron two ion وشُحنته two plus\nيعني موجبة\nولو خِسِر three electrons يفضل\ntwenty-three ويبقى iron three ion كده\nوفيه atoms تانية بتكسب electrons زي الـ\nchlorine والـ oxygen كده\nالـ chlorine فيه seventeen protons و\nseventeen electrons ولو كِسِب one يبقوا\neighteen كلهم\nفالسالب بقى أكتر وده اسمه الـ chloride ion\nالسالب\nالـ anion ده negative ion والـ charge قد\nالـ electrons اللي الـ atom كِسِبها\nوالـ oxygen eight protons بيكسب two فيبقى\nten electrons وشُحنته two minus يعني سالبة\nيعني اللي يِخسر electrons يبقى cation\nواللي يِكسب يبقى anion سالب\nالـ protons بتحدد الـ element والـ\nelectrons بتحدد الـ charge كده\nعندنا الـ copper والـ atomic number بتاعه\ntwenty-nine كمان\nعايزين نعرف الـ copper two ion فيه كام\nelectron بالظبط\nأول خطوة الـ protons twenty-nine زي الـ\natomic number بالظبط\nتاني خطوة الـ atom الـ neutral فيه\ntwenty-nine electrons برضه\nتالت خطوة الـ charge two plus يعني خِسِر\ntwo electrons كده\nرابع خطوة twenty-nine minus two equals\ntwenty-seven electrons كده\nيعني الـ copper two ion twenty-nine\nprotons و twenty-seven electrons ولسه\ncopper نفسه\nالقاعدة electrons الـ cation هي الـ atomic\nnumber minus الـ charge بتاعته\nدورك twenty-five protons و twenty-three\nelectrons والـ manganese فيه twenty-five\nبرضه\nأنهي element atom ولا cation ولا anion\nوالـ charge كام وقّف وفكّر\nالإجابة ده manganese وهو cation شُحنته two\nplus يعني موجبة\nالـ protons بتحدد العنصر وخِسِر two\nelectrons فبقى الـ manganese two ion كده\nطب الكلام ده هيفيدك فين في الفصل\nالفصل بيكتب الـ iron two والـ iron three\nكتير وإنت دلوقتي فاهمهم\nفي درس الـ ions وإن الـ electrons بتاعة\nالـ four s بتطلع الأول\nالـ four s ده جزء من مستويات الـ electrons\nوالفصل هيشرحه\nوكمان درس الـ ionic والـ covalent bonds\nهيستخدم الـ cation والـ anion دول\nالخلاصة الـ atom لما يِخسر electrons يبقى\ncation ولما يِكسب يبقى anion سالب\nوالـ protons ثابتة و electrons الـ cation\nهي الـ atomic number minus الـ charge\nبتاعته\nيعني تِخسر electrons تبقى cation تِكسب\nelectrons تبقى anion كده","countable":false,"session_id":"chem-s3-en.ch1.s3","session_no":3,"session_ord":77,"see_also":[{"item_id":"chem-s3-en.lesson-te.ion-configuration","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Ions: 4s electrons are lost first","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":133.49,"kind":"pause_question","spec":{"answer":"24: الموجب معناه إنه خسر electrons، فـ 26 − 2 = 24.","prompt":"Fe²⁺ (الـ charge 2+): فيه كام electron؟ (الـ Fe atom فيه 26 electron)","options":[{"id":"a","text":"24","correct":true},{"id":"b","text":"28","correct":false},{"id":"c","text":"26","correct":false}],"answer_t_s":137.38,"concept_id":"chem.ions"},"content_lang":"ar-EG"},{"id":"think-2","t_s":268.44,"kind":"pause_question","spec":{"answer":"manganese (الـ protons بتحدد الـ element)، خسر 2 electrons، فهو cation شحنته 2+: Mn²⁺.","prompt":"25 protons و 23 electrons (الـ manganese فيه 25 proton): أنهي element؟ atom ولا cation ولا anion؟ والـ charge كام؟","options":[{"id":"a","text":"manganese، cation، 2+","correct":true},{"id":"b","text":"manganese، anion، 2−","correct":false},{"id":"c","text":"element تاني، عشان الـ electrons اتغيرت","correct":false}],"answer_t_s":272.44,"concept_id":"chem.ions"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.ions"]},{"id":"chem-s3-en.video-walkthrough-bond.chemical-bond-basic","kind":"walkthrough","version":4,"ord":253,"content_lang":"ar-EG","primary_concept_id":"bond.chemical-bond-basic","concepts":[{"concept_id":"bond.chemical-bond-basic","role":"primary"}],"title":"Ionic and covalent bonds: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-bond.chemical-bond-basic v2 (hook s1: sodium soft reactive metal + chlorine poisonous gas -> table salt, MCQ options b 'shared pair' and c 'only mixed' = the two misconceptions refuted in s2; s2 FlowDiagram Na (2, 8, 1) -> Na+ (2, 8), Cl (2, 8, 7) -> Cl- (2, 8, 8), KeyTerm 'Ionic bond' verbatim, 'stable outer level'; s3 KeyTerm 'Covalent bond' verbatim, 'Each chlorine atom has 7 outer electrons and needs one more. Neither gives one away, so they share a pair'; s4 check: MgO (Mg 2 outer electrons, O needs 2: layer feedback) used as the worked example, metal + non-metal -> transfer / non-metals together -> sharing (layer explanation); s5 recap bullets = s4 recap lines and 'a third way, the metallic bond'). Concept bond.chemical-bond-basic v2: no recorded misconceptions; s2 refutes the lesson hook's two wrong options (share in NaCl ✕ -> transfer ✓; salt = just mixed ✕ -> new substance, new properties (lesson feedback c) ✓). Prereq chem.ions summary (lose -> positive ion, gain -> negative ion). Dependents named in s4 by map title: 'Metallic bond' (bond.metallic-bond; book p.13 point 3b names the metallic bond) and 'Bond breaking and bond forming' (chem.bond-breaking-energy); no new facts about them (no electron sea, no energy). Hidden-absolute guard (chem-s3-en.ch1.guard.hidden-absolutes 'two ways'): the video never says there are only two bonds; s4l2 names the metallic bond as a third. Rules stated with 'Usually' (غالبًا) for metal + non-metal / non-metal + non-metal. Terms (defined at first use, on screen + spoken meaning): s1 atom(s), electron(s), chemical bond (3); s2 levels, outer level, stable, ion, positive ion / negative ion, Ionic bond, Covalent bond, metal, non-metal. s3/s4 introduce none (s4 chips are dependent concept titles). Element symbols appear only as disc labels in the visuals; screen_text uses the names that are spoken. Self-check: NEW case hydrogen + chlorine (hydrogen chloride; book p.67 (Ch.3) names dry hydrogen chloride a covalent compound) — worked example is magnesium + oxygen; neither appears in the lesson's s1-s3. Predicts: s2l7 (~1:25), s3l9 (~3:55). not-in-source: atoms are the tiny particles that matter is made of (prereq concept sci.matter-particles title); electrons move around the centre of the atom with a negative charge; electrons are arranged in levels (layers) around the centre; the outer level is the last level; sodium is shiny and conducts electricity (metal property, concept chem.metal-properties); oxygen and hydrogen are non-metals; Mg 2, 8, 2 and O 2, 6 shells (lesson gives only '2 outer electrons' / 'needs 2'); hydrogen chloride forms by sharing one pair (covalent); table salt is safe to eat in food. Estimated duration ≈ 322 s (632 narration words at ~2.4 words/s + 41.8 s pauses + joins); planning aid only.","title":"Ionic and covalent bonds: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"YK.camera pushes in on the shaker; grains fall from it (YK.flyer ×6, short arcs, C.text) on cue 'بنرشه'; YK.tag 'table salt' (48) beside the heap on cue 'الطعام'.","tts_text":"بص على ملح الطعام اللي بنرُشّه على الأكل كل يوم.","screen_text":"table salt","pause_after_s":0.4},{"id":"s1l3","visual":"Stage splits: the salt heap shrinks to the bottom centre (alpha 0.35); top-left a soft grey block YK.cube(ctx, 1050, 420, 180, {color: C.steel}) being cut by a knife YK.icon('knife') on cue 'طرية' (cut face shiny, no colour beyond grey); label 'sodium' (YK.tag 44) on cue 'sodium'. Text panel: YK.fpara 'sodium: soft, reacts strongly' (40) at (96, 300). The word metal is kept for s2.","tts_text":"الملح ده جاي من مادتين: الأولى اسمها sodium، طرية وبتتفاعل بشدة.","screen_text":"sodium: soft, reacts strongly","pause_after_s":0.4},{"id":"s1l4","visual":"Top-right: a closed glass jar (YK.beaker(ctx, 1560, 430, 220, 280, {level: 0.95, color: 'rgba(200,230,140,0.25)'}) — a pale gas fill, no claim beyond 'gas') pops in on cue 'chlorine' with YK.tag 'chlorine' (44); a small warning triangle drawn with ctx paths (C.coral) on cue 'سام'. YK.fpara 'chlorine: a poisonous gas' (40) at (96, 420).","tts_text":"والتانية اسمها chlorine، وده غاز سام وخطير جدًا.","screen_text":"chlorine: a poisonous gas","pause_after_s":0.4},{"id":"s1l5","visual":"Cause → effect left → right: the sodium block and the gas jar slide toward the centre on cue 'يتحدوا' and flash once (YK.flashRect), the salt heap grows back to full size on 'ملح'; word line YK.formula 'sodium + chlorine -> table salt' (44, arrow gold) builds in the text panel (96, 560) on cues 'sodium' / 'chlorine' / 'ملح'.","tts_text":"ولما الـ sodium والـ chlorine يتّحدوا، بيطلع ملح الطعام اللي بناكله.","screen_text":"sodium + chlorine → table salt","pause_after_s":0.4},{"id":"s1l6","visual":"Camera zooms on one grain of salt (YK.zoomThrough(ctx, t, {from: drawHeap, to: drawGrain, badge: '×10^7'}) from cue 'ماسكهم'); a big gold '?' drawn with ctx paths over the grain on 'بعض'. YK.fpara 'What holds them together?' (48) in the text panel. Question left open: answered in s2.","tts_text":"طب إيه اللي ماسكهم في بعض جوه حبة الملح دي؟","screen_text":"What holds them together?","pause_after_s":1},{"id":"s1l7","visual":"Zoom continues into the grain (YK.zoomThrough second stage, YK.scaleBadge corner): a grid of small discs (YK.atomDisc ×12, r 34, el '' symbol:false, grey) appears on cue 'جسيمات'. YK.termCard(ctx, 96, 380, {term: 'atoms', def: 'the tiny particles that matter is made of', align: 'left', p: on cue 'atoms'}).","tts_text":"أي مادة حوالينا متكوّنة من atoms، يعني جسيمات صغيرة جدًا.","screen_text":"atoms: the tiny particles that matter is made of","pause_after_s":0.4},{"id":"s1l8","visual":"Two discs come forward from the grid: YK.atomDisc(ctx, 1080, 560, 90, {el: 'Na'}) on cue 'sodium' and YK.atomDisc(ctx, 1540, 560, 110, {el: 'Cl'}) on cue 'chlorine'; YK.tag 'sodium atom' / 'chlorine atom' (40) under them on the same cues; the grid dims to 30%.","tts_text":"فيه atom من الـ sodium، و atom تاني من الـ chlorine كده.","screen_text":"sodium atom · chlorine atom","pause_after_s":0.4},{"id":"s1l9","visual":"The Na disc opens into a Bohr picture YK.atom(ctx, 1080, 560, {shells: [2,8,1], size: 230, rotate: t, reveal: on cue 'جسيمات'}) — nucleus first, electrons (YK.dot cyan) on the rings on cue 'electrons'; a small '−' badge (ctx text, mono) beside one electron on 'سالبة'. YK.termCard(ctx, 96, 380, {term: 'electrons', def: 'tiny particles with a negative charge that move around the centre of the atom', align: 'left'}).","tts_text":"وجوه الـ atom فيه جسيمات أصغر سالبة، اسمها electrons، بتلِفّ حوالين المركز.","screen_text":"electrons: tiny particles with a negative charge that move around the centre of the atom","pause_after_s":0.4},{"id":"s1l10","visual":"Back to the two discs (Na, Cl) side by side; a gold link line (ctx stroke, C.gold, lw 8) draws between them on cue 'بتمسك' and pulses (YK.pulse) on 'chemical'. YK.termCard(ctx, 96, 380, {term: 'chemical bond', def: 'what holds atoms together', align: 'left', p: on cue 'chemical'}).","tts_text":"والحاجة اللي بتمسك الـ atoms في بعض اسمها chemical bond، أو رابطة.","screen_text":"chemical bond: what holds atoms together","pause_after_s":0.4},{"id":"s1l11","visual":"Micro-recap: the three term cards collapse into three YK.chip kind 'concept' in a row in the text panel (96, 300 / 420 / 540) on cues 'atom', 'electron', 'chemical'; the stage picture of each (disc grid, Bohr atom, gold link) flashes in the same order (YK.flashRect).","tts_text":"يبقى عندنا atom، و electron، و chemical bond، تلات كلمات مهمة.","screen_text":"atom · electron · chemical bond","pause_after_s":1},{"id":"s2l2","visual":"Stage: YK.atom(ctx, 1080, 580, {shells: [2,8,1], size: 260, rotate: t}) (sodium); the three rings light one after another from the centre out on cue 'levels' (YK.glowCircle on each ring radius). YK.termCard(ctx, 96, 380, {term: 'levels', def: 'layers of electrons around the centre', align: 'left'}).","tts_text":"الـ electrons بتلِفّ في levels، يعني طبقات حوالين المركز.","screen_text":"levels: layers of electrons around the centre","pause_after_s":0.4},{"id":"s2l3","visual":"Ring counts pop beside the rings left → right: '2' on cue 'two', '8' on 'eight', '1' on 'one' (YK.formula mono 48); label 'sodium' over the atom; text panel YK.formula 'sodium: 2, 8, 1' (56).","tts_text":"الـ sodium فيه two و eight، وفي الطبقة الأخيرة one electron بس.","screen_text":"sodium: 2, 8, 1","pause_after_s":0.4},{"id":"s2l4","visual":"The outer ring of sodium glows gold (YK.atom highlightShell: 2) on cue 'الأخيرة'; its single electron pulses (YK.glowCircle) on 'الشغل'. YK.termCard(ctx, 96, 380, {term: 'outer level', def: 'the last level', align: 'left', p: on cue 'outer'}).","tts_text":"الطبقة الأخيرة دي اسمها outer level، وهي اللي بيحصل فيها الشغل.","screen_text":"outer level: the last level","pause_after_s":0.4},{"id":"s2l5","visual":"Second atom slides in on the right: YK.atom(ctx, 1560, 580, {shells: [2,8,7], size: 260, rotate: t, highlightShell: 2}) on cue 'chlorine'; counts '2', '8', '7' pop on 'two' / 'eight' / 'seven'; text panel YK.formula 'chlorine: 2, 8, 7' (56).","tts_text":"والـ chlorine فيه two و eight، وفي الـ outer level seven electrons كمان.","screen_text":"chlorine: 2, 8, 7 · outer level: 7 electrons","pause_after_s":0.4},{"id":"s2l6","visual":"An empty dashed slot (ctx dashed circle, C.gold) blinks on chlorine's outer ring on cue 'محتاج'; YK.tag 'needs 1 more electron' (40) on cue 'one'.","tts_text":"الـ chlorine محتاج one electron كمان، عشان طبَقته الأخيرة تبقى مستقرة.","screen_text":"chlorine needs 1 more electron","pause_after_s":0.4},{"id":"s2l7","visual":"YK.predictCard(ctx, t, {at: YK.cueX('s2l7','طب'), until: YK.cue('s2l8') + 0.4, think: YK.cueEnd('s2l7'), end: YK.cue('s2l8'), kind: 'PREDICT', q: 'Sodium meets chlorine: where does the electron go?'}); stage: the two atoms side by side, sodium's outer electron pulsing on cue 'electron'. Nothing answered during the 3 s silence.","tts_text":"طب لما الـ sodium يقابل الـ chlorine، الـ electron ده هيروح فين؟ فكّر.","screen_text":"PREDICT: sodium meets chlorine. Where does the electron go?","pause_after_s":3},{"id":"s2l8","visual":"Answer: sodium's outer electron flies on an arc into chlorine's empty slot with a trail (YK.flyer(ctx, p, x0, y0, x1, y1, {trail: true}), p from cue 'بيدّي' to 'فبيتنقل'); sodium's empty outer ring fades away. YK.answerSlot(ctx, t, {at: YK.cue('s2l8','بيدّي'), text: 'sodium gives 1 electron to chlorine', x: 420, y: 760}).","tts_text":"الـ sodium بيدّي الـ chlorine الـ electron بتاعه، فبيتنقل من واحد للتاني.","screen_text":"sodium gives 1 electron to chlorine","pause_after_s":0.4},{"id":"s2l9","visual":"Charge badges appear on the atoms (ctx text in a small circle): '+' on sodium on cue 'موجب' (C.cyan), '−' on chlorine on cue 'سالب'#2 (C.coral); text panel YK.formula 'electron: −  ·  lose one → +  ·  gain one → −' (44) builds on cues 'سالب'#1 / 'موجب' / 'سالب'#2.","tts_text":"الـ electron سالب، فاللي يِخسره يبقى موجب، واللي ياخده يبقى سالب.","screen_text":"electron: −  ·  lose one → +  ·  gain one → −","pause_after_s":0.4},{"id":"s2l10","visual":"Both atoms shrink into YK.atomDisc with charge badges: YK.atomDisc(ctx, 1080, 580, 80, {el: 'Na', charge: '+'}) and YK.atomDisc(ctx, 1560, 580, 120, {el: 'Cl', charge: '−'}) on cue 'مشحون'. YK.termCard(ctx, 96, 380, {term: 'ion', def: 'an atom that lost or gained electrons, so it has a charge', align: 'left', p: on cue 'ion'}).","tts_text":"الـ atom اللي خِسِر أو كِسِب electrons بيبقى مشحون، واسمه ion كده.","screen_text":"ion: an atom that lost or gained electrons, so it has a charge","pause_after_s":0.4},{"id":"s2l11","visual":"YK.tag 'positive ion' (40, cyan) under sodium on cue 'positive'; YK.tag 'negative ion' (40, coral) under chlorine on cue 'negative'; text panel YK.list rows 'sodium lost 1 → positive ion' / 'chlorine gained 1 → negative ion' on the same cues.","tts_text":"الـ sodium خِسِر one فبقى positive ion، والـ chlorine كِسِب فبقى negative ion كده.","screen_text":"sodium lost 1 → positive ion · chlorine gained 1 → negative ion","pause_after_s":0.4},{"id":"s2l12","visual":"Inset (YK.panel 1180, 200, 600, 300): the two Bohr pictures again, sodium now [2,8] and chlorine [2,8,8], outer rings gold on cue 'outer'; '8' counts pop on both outer rings on 'eight'; YK.tag 'stable' (44, mint) on cue 'stable'.","tts_text":"ودلوقتي الـ outer level في الاتنين فيه eight، يعني stable، مستقر.","screen_text":"2, 8 · 2, 8, 8: stable outer level","pause_after_s":0.4},{"id":"s2l13","visual":"Gold attraction lines (three short dashed strokes, C.gold) grow between the two discs on cue 'بيشدوا' and the discs slide together until they touch on 'بتتجاذب'; tags 'positive' / 'negative' stay on their discs.","tts_text":"والـ positive والـ negative بيشِدّوا بعض، عشان الشحنات المختلفة بتتجاذب.","screen_text":"positive and negative attract","pause_after_s":0.4},{"id":"s2l14","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 360, {term: 'Ionic bond', def: 'The electrostatic attraction between a positive ion and a negative ion, formed by transfer of electrons.', keys: ['attraction', 'transfer of electrons'], align: 'left', p: on cue 'ionic'}); stage: the touching pair glows gold (YK.glow) on cue 'ionic'; tags 'positive ion' / 'negative ion' pulse on their cues.","tts_text":"الشدّ ده بين الـ positive ion والـ negative ion اسمه ionic bond كده.","screen_text":"Ionic bond: The electrostatic attraction between a positive ion and a negative ion, formed by transfer of electrons.","pause_after_s":0.4},{"id":"s2l14a","visual":"The definition card of s2l14 stays; its key 'transfer of electrons' highlights gold on cue 'بنقل'; stage: a ghost replay of the flying electron Na → Cl (YK.flyer with trail, alpha 0.5) on the same cue.","tts_text":"والـ ions دي اتكوّنت أصلًا بنقل الـ electrons، زي ما شفنا.","screen_text":"formed by transfer of electrons","pause_after_s":0.8},{"id":"s2l15","visual":"Misconception (lesson hook option b): YK.mythLine(ctx, t, {at: YK.cue('s2l15'), wrongAt: YK.cueX('s2l15','غلط'), until: YK.cueEnd('s2l16') + 1.5, text: 'Sodium and chlorine share electrons', x: 96, y: 300, size: 44}) — coral text with ✕ (YK.wrongMark) from the «غلط» cue for its whole visible time, no strike-through. Stage: a faint ghost of a shared pair between the discs, crossed by YK.wrongMark(ctx, 1320, 580, 110) on the same cue.","tts_text":"فيه ناس فاكرة إن الـ sodium والـ chlorine بيتشاركوا في الـ electrons، وده غلط.","screen_text":"Sodium and chlorine share electrons ✕","pause_after_s":0.4},{"id":"s2l16","visual":"Fix (held ≥ the myth): replay of the electron flight Na → Cl (YK.flyer with trail) on cue 'بيدّي'; charge badges pop on 'ions'; YK.rightMark next to the fix line 'Sodium gives its electron away → ions' (YK.fpara 44, mint, 96, 420) on cue 'ions'. Myth line and its ✕ stay above.","tts_text":"الـ sodium بيدّي الـ electron خالص، فبيتكوّن ions، مش مشاركة.","screen_text":"Sodium gives its electron away → ions ✓","pause_after_s":0.4},{"id":"s2l17","visual":"Second misconception (lesson hook option c): new picture — a split box: left half grey sodium bits and pale gas puffs simply scattered together (YK.dot mix, seeded) on cue 'متخلطين'. YK.mythLine(ctx, t, {at: YK.cue('s2l17'), wrongAt: YK.cueX('s2l17','غلط'), until: YK.cueEnd('s2l18') + 1.5, text: 'Salt is just sodium and chlorine mixed', x: 96, y: 300, size: 44}) with ✕ for its whole visible time, no strike-through.","tts_text":"وناس فاكرة إن الملح مجرد sodium و chlorine متخلطين، وده غلط برضه.","screen_text":"Salt is just sodium and chlorine mixed ✕","pause_after_s":0.4},{"id":"s2l18","visual":"Fix: the right half of the box shows white salt grains (no grey metal, no gas) on cue 'جديدة'; zoom inset: alternating Na+ / Cl− discs (YK.atomDisc with charge badges, 3×3) held by gold links on cue 'ionic'. YK.rightMark + 'New substance, new properties: held by the ionic bond' (YK.fpara 44, mint, 96, 420). Myth line stays above with its ✕.","tts_text":"الملح مادة جديدة بصفات جديدة، ماسكها الـ ionic bond في بعض.","screen_text":"New substance, new properties: held by the ionic bond ✓","pause_after_s":0.4},{"id":"s2l19","visual":"New picture: two YK.atom(ctx, x, 580, {shells: [2,8,7], size: 230, highlightShell: 2}) at x 1150 / 1500 slide toward each other on cue 'قابلوا'; YK.tag 'chlorine' under each on cue 'chlorine'; text panel YK.fpara '2 chlorine atoms meet' (44).","tts_text":"طب لو two atoms من الـ chlorine قابلوا بعض، يحصل إيه؟","screen_text":"2 chlorine atoms meet","pause_after_s":0.4},{"id":"s2l20","visual":"Both outer rings show a blinking empty slot (dashed gold) on cue 'محتاج'; an outer electron of the left atom starts to hop right and springs back (YK.tween, outBack) on 'فمحدش', the same on the right atom (tug with no winner).","tts_text":"كل واحد محتاج electron كمان، فمحدش فيهم هيدّي التاني حاجة.","screen_text":"Each needs 1 more electron: neither gives one away","pause_after_s":0.4},{"id":"s2l21","visual":"The outer rings overlap (atoms move to x 1220 / 1430); one electron from each atom moves into the overlap on cue 'يحط'; a gold ellipse (ctx, C.gold, alpha 0.25) encloses the two dots on 'زوج'.","tts_text":"فبيتشاركوا: كل واحد يحط electron، ويبقى فيه زوج electrons في النص.","screen_text":"They share a pair of electrons","pause_after_s":0.4},{"id":"s2l22","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 360, {term: 'Covalent bond', def: 'A bond formed by sharing pairs of electrons between two atoms.', keys: ['sharing pairs of electrons'], align: 'left', p: on cue 'covalent'}); the shared pair pulses gold on the same cue.","tts_text":"الرابطة دي اسمها covalent bond، يعني الـ electrons متشاركة بين الـ atoms دي.","screen_text":"Covalent bond: A bond formed by sharing pairs of electrons between two atoms.","pause_after_s":0.8},{"id":"s2l23","visual":"New picture: two-column board (YK.panel 820–1300 accent C.cyan, YK.panel 1340–1824 accent C.amber). Left column: a freshly cut sodium block (YK.cube, C.steel, shine sweep) on cue 'sodium', header 'metal' on cue 'metal', a small circuit lamp YK.icon('lamp') lights on 'بتوصّل'. YK.termCard(ctx, 96, 380, {term: 'metal', def: 'shiny, conducts electricity', align: 'left'}).","tts_text":"الـ sodium من نوع اسمه metal، والـ metals لامعة وبتوصّل الكهربا.","screen_text":"metal: shiny, conducts electricity · sodium","pause_after_s":0.4},{"id":"s2l24","visual":"Right column: header 'non-metal' on cue 'non'; one YK.atomDisc (el 'Cl', r 56) pops in on cue 'chlorine' with a YK.tag name under it. YK.termCard(ctx, 96, 560, {term: 'non-metal', def: 'usually dull, does not conduct electricity', align: 'left'}) on cue 'non'.","tts_text":"والـ chlorine نوعه non-metal، يعني غالبًا مش لامع ومبيوصّلش الكهربا.","screen_text":"non-metal: usually dull, does not conduct electricity · chlorine","pause_after_s":0.4},{"id":"s2l24a","visual":"Same right column: two more YK.atomDisc (el 'O', 'H', r 56) pop in under the Cl disc on cues 'oxygen' / 'hydrogen' with YK.tag names under them.","tts_text":"ومن الـ non-metals كمان الـ oxygen والـ hydrogen، خلّيهم في بالك.","screen_text":"non-metals: oxygen · hydrogen","pause_after_s":0.4},{"id":"s2l25","visual":"A gold arrow links the two columns (YK.flow single edge) on cue 'metal' / 'non'; at its middle a mini replay of the electron hop (YK.flyer) on 'بالنقل'; YK.formula 'metal + non-metal -> ionic bond' (44) in the text panel, 'Usually' (gold, 40) on cue 'وغالبًا'.","tts_text":"وغالبًا الـ metal مع الـ non-metal بيعملوا ionic bond بالنقل.","screen_text":"Usually: metal + non-metal → ionic bond","pause_after_s":0.4},{"id":"s2l26","visual":"Inside the right column the Cl and O discs lean together with a gold shared pair between them on cue 'بيتشاركوا'; YK.formula 'non-metal + non-metal -> covalent bond' (44) under the first rule, 'Usually' (gold) on cue 'غالبًا'.","tts_text":"والـ non-metals مع بعض، غالبًا بيتشاركوا، فيعملوا covalent bond بينهم.","screen_text":"Usually: non-metal + non-metal → covalent bond","pause_after_s":1},{"id":"s3l2","visual":"Stage: YK.atomDisc(ctx, 1100, 560, 96, {el: 'Mg'}) on cue 'magnesium' and YK.atomDisc(ctx, 1520, 560, 84, {el: 'O'}) on cue 'oxygen'; YK.tag names under them; header 'magnesium + oxygen: which chemical bond?' on cue 'chemical' (YK.fpara 44) in the text panel. The worked steps stack below it (YK.list, LTR).","tts_text":"عندنا الـ magnesium مع الـ oxygen، الـ chemical bond بينهم نوعه إيه؟","screen_text":"magnesium + oxygen: which chemical bond?","pause_after_s":0.4},{"id":"s3l3","visual":"YK.list item 1 builds on cues 'magnesium' / 'metal' / 'oxygen' / 'non'; YK.tag 'metal' (cyan) under Mg and 'non-metal' (amber) under O on the same cues; the s2 two-column board flashes small in the stage corner (YK.flashRect) as a callback.","tts_text":"أول خطوة: الـ magnesium نوعه metal، والـ oxygen نوعه non-metal كده.","screen_text":"Step 1: magnesium → metal · oxygen → non-metal","pause_after_s":0.4},{"id":"s3l4","visual":"The discs open into YK.atom pictures: magnesium {shells: [2,8,2], highlightShell: 2} and oxygen {shells: [2,6], highlightShell: 1} on cue 'outer'; '2' badge on magnesium's outer ring on 'two'#1, two dashed empty slots on oxygen's outer ring on 'محتاج'. YK.list item 2.","tts_text":"تاني خطوة: الـ magnesium في الـ outer level عنده two، والـ oxygen محتاج two.","screen_text":"Step 2: magnesium: 2 in the outer level · oxygen needs 2","pause_after_s":0.4},{"id":"s3l5","visual":"The two outer electrons of magnesium fly into oxygen's slots one after the other with trails (YK.flyer ×2, staggered 0.3) on cue 'بيدّي' → 'electrons'; magnesium's outer ring fades. YK.list item 3.","tts_text":"تالت خطوة: الـ magnesium بيدّي الـ oxygen الـ two electrons دول.","screen_text":"Step 3: magnesium gives 2 electrons to oxygen","pause_after_s":0.4},{"id":"s3l6","visual":"Atoms collapse into YK.atomDisc with charge badges ('+' cyan on Mg on cue 'positive', '−' coral on O on cue 'negative'); YK.list item 4 on the same cues.","tts_text":"رابع خطوة: الـ magnesium بقى positive ion، والـ oxygen بقى negative ion كده.","screen_text":"Step 4: magnesium → positive ion · oxygen → negative ion","pause_after_s":0.4},{"id":"s3l7","visual":"Gold attraction lines and the discs slide together on cue 'بيشدوا'; YK.rightMark + 'ionic bond' (YK.fpara 48, mint) on cue 'ionic'; a small salt-grain thumbnail from s2l18 flashes beside it on 'الملح'.","tts_text":"والاتنين بيشِدّوا بعض، يبقى الرابطة هنا ionic bond، زي الملح بالظبط.","screen_text":"They attract → ionic bond ✓","pause_after_s":1},{"id":"s3l8","visual":"Self-check on a NEW case (worked example was magnesium + oxygen; the lesson check used other substances): stage clears; YK.atomDisc(ctx, 1150, 560, 56, {el: 'H'}) on cue 'hydrogen' and YK.atomDisc(ctx, 1500, 560, 110, {el: 'Cl'}) on cue 'chlorine'; label 'hydrogen chloride' (44) over them on cue 'chloride'. YK.predictCard(ctx, t, {at: YK.cue('s3l8'), until: YK.cue('s3l10') + 0.4, think: YK.cueEnd('s3l9'), end: YK.cue('s3l10'), kind: 'QUICK CHECK', q: 'Hydrogen + chlorine: ionic bond or covalent bond?'}).","tts_text":"دورك: الـ hydrogen مع الـ chlorine بيكوّنوا مادة اسمها hydrogen chloride كده.","screen_text":"Your turn: hydrogen + chlorine → hydrogen chloride","pause_after_s":0.4},{"id":"s3l9","visual":"The question stays; two YK.chip options 'ionic bond' / 'covalent bond' under the atoms on their cues; YK.checkPause(ctx, 1307, 880, {t, start: YK.cueEnd('s3l9'), dur: 4}) think ring + countdown through the silence; no answer, no hint during the pause.","tts_text":"الرابطة دي ionic bond ولا covalent bond؟ وقّف الفيديو وفكّر شوية.","screen_text":"Ionic bond or covalent bond?","pause_after_s":4},{"id":"s3l10","visual":"Answer: the 'covalent bond' chip glows mint (the other dims to 30%) + YK.rightMark on cue 'covalent'; YK.answerSlot(ctx, t, {at: YK.cue('s3l10','covalent'), text: 'Covalent bond', x: 420, y: 700}); tags 'non-metal' (amber) under H and Cl on cue 'non'.","tts_text":"الإجابة: covalent bond، عشان الـ hydrogen والـ chlorine الاتنين non-metals كده.","screen_text":"Covalent bond ✓ hydrogen, chlorine: non-metals","pause_after_s":0.4},{"id":"s3l11","visual":"Reason as a picture (same drawing as s2l20–s2l21): H [1] and Cl [2,8,7] Bohr atoms (YK.atom), outer rings overlap on cue 'فبيتشاركوا', a gold ellipse encloses the shared pair on 'زوج'; YK.rightMark on the inset.","tts_text":"محدش فيهم بيدّي الـ electron خالص، فبيتشاركوا في زوج electrons بينهم.","screen_text":"Neither gives an electron away: they share a pair","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الباب؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, 'Metallic bond', {kind: 'concept', align: 'left'}) (map title exactly) on cue 'metallic'; under it a small block of identical grey discs (YK.lattice(ctx, 900, 320, 420, 260, {rows: 3, cols: 5, reveal: on cue 'metal'})) — no electrons or charges drawn (that is the chapter's lesson); YK.tag 'between metal atoms' (36) on cue 'atoms'.","tts_text":"في الباب هتقابل الـ metallic bond، رابطة تالتة بين الـ metal atoms وبعضها.","screen_text":"Metallic bond: between metal atoms","pause_after_s":0.4},{"id":"s4l3","visual":"Second YK.chip(ctx, 820, 640, 'Bond breaking and bond forming', {kind: 'concept', align: 'left'}) on cue 'breaking'; beside it a tiny picture of two discs with a gold link that snaps (gap opens) on 'بتتكسر' and a new gold link that joins another pair on 'بتتكوّن'. No energy arrows or numbers (taught in that lesson).","tts_text":"وهتقابل الـ bond breaking والـ bond forming، يعني روابط بتتكسر وروابط بتتكوّن.","screen_text":"Bond breaking and bond forming","pause_after_s":0.4},{"id":"s4l4","visual":"Both chips get a thin gold line down to one chip 'chemical bond' (YK.chip kind 'concept', 96, 520 in the text panel) on cue 'chemical'; the s1 gold link picture flashes (YK.flashRect) on 'عملناه'.","tts_text":"والاتنين مبنيين على إنك عارف الـ chemical bond يعني إيه، وده اللي عملناه.","screen_text":"Both start from: what a chemical bond is","pause_after_s":0.6},{"id":"s4l5","visual":"Recap (s4l5–s4l7 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l5'), until: YK.cue('s4l7'), title: 'Ionic and covalent bonds', line: 'Ionic bond: one atom gives electrons, the other takes them', pulse: [{word: 'Ionic', at: YK.cueX('s4l5','ionic')}, {word: 'gives', at: YK.cueX('s4l5','بيدّي')}]}); stage: the Na → Cl electron hop of s2l8 replays small.","tts_text":"الخلاصة: في الـ ionic bond، فيه atom بيدّي electrons والتاني بياخدها.","screen_text":"Ionic bond: one atom gives electrons, the other takes them","pause_after_s":0.4},{"id":"s4l6","visual":"Same recap card, second line 'Covalent bond: two atoms share pairs of electrons' added on cue 'covalent'; stage: the Cl–Cl shared pair of s2l21 replays small.","tts_text":"وفي الـ covalent bond، الـ atoms بتتشارك في أزواج electrons بينها.","screen_text":"Covalent bond: two atoms share pairs of electrons","pause_after_s":0.6},{"id":"s4l7","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Ionic and covalent bonds', line: 'Ionic: give and take. Covalent: share.', t, pulse: [{word: 'Ionic', at: YK.cueX('s4l7','ionic')}, {word: 'Covalent', at: YK.cueX('s4l7','covalent')}]}) held ≥ 2.5 s; no fade to black, no outro.","tts_text":"يعني الـ ionic بيدّي وياخد، والـ covalent بيشارك.","screen_text":"Ionic: give and take. Covalent: share.","pause_after_s":1.5}],"logline":"هتعرف يعني إيه chemical bond، والفرق بين الـ ionic bond والـ covalent bond، وتقرر أنهي واحدة بتتكوّن بين أي اتنين atoms.","segments":[{"id":"s1","title":"Table salt: what holds it together","concept_id":"bond.chemical-bond-basic"},{"id":"s2","title":"Ionic and covalent bonds","concept_id":"bond.chemical-bond-basic"},{"id":"s3","title":"Magnesium and oxygen: which bond?","concept_id":"bond.chemical-bond-basic"},{"id":"s4","title":"Where Chapter 1 uses 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على ملح الطعام اللي بنرُشّه على الأكل\nكل يوم\nالملح ده جاي من مادتين الأولى اسمها sodium\nطرية وبتتفاعل بشدة\nوالتانية اسمها chlorine وده غاز سام وخطير\nجدًا\nولما الـ sodium والـ chlorine يتّحدوا\nبيطلع ملح الطعام اللي بناكله\nطب إيه اللي ماسكهم في بعض جوه حبة الملح دي\nأي مادة حوالينا متكوّنة من atoms يعني\nجسيمات صغيرة جدًا\nفيه atom من الـ sodium و atom تاني من الـ\nchlorine كده\nوجوه الـ atom فيه جسيمات أصغر سالبة اسمها\nelectrons بتلِف حوالين المركز\nوالحاجة اللي بتمسك الـ atoms في بعض اسمها\nchemical bond أو رابطة\nيبقى عندنا atom و electron و chemical bond\nتلات كلمات مهمة\nالـ electrons بتلِف في levels يعني طبقات\nحوالين المركز\nالـ sodium فيه two و eight وفي الطبقة\nالأخيرة one electron بس\nالطبقة الأخيرة دي اسمها outer level وهي\nاللي بيحصل فيها الشغل\nوالـ chlorine فيه two و eight وفي الـ\nouter level seven electrons كمان\nالـ chlorine محتاج one electron كمان عشان\nطبَقته الأخيرة تبقى مستقرة\nطب لما الـ sodium يقابل الـ chlorine الـ\nelectron ده هيروح فين فكّر\nالـ sodium بيدّي الـ chlorine الـ electron\nبتاعه فبيتنقل من واحد للتاني\nالـ electron سالب فاللي يِخسره يبقى موجب\nواللي ياخده يبقى سالب\nالـ atom اللي خِسِر أو كِسِب electrons\nبيبقى مشحون واسمه ion كده\nالـ sodium خِسِر one فبقى positive ion\nوالـ chlorine كِسِب فبقى negative ion كده\nودلوقتي الـ outer level في الاتنين فيه\neight يعني stable مستقر\nوالـ positive والـ negative بيشِدّوا بعض\nعشان الشحنات المختلفة بتتجاذب\nالشد ده بين الـ positive ion والـ negative\nion اسمه ionic bond كده\nوالـ ions دي اتكوّنت أصلًا بنقل الـ\nelectrons زي ما شفنا\nفيه ناس فاكرة إن الـ sodium والـ chlorine\nبيتشاركوا في الـ electrons وده غلط\nالـ sodium بيدّي الـ electron خالص\nفبيتكوّن ions مش مشاركة\nوناس فاكرة إن الملح مجرد sodium و chlorine\nمتخلطين وده غلط برضه\nالملح مادة جديدة بصفات جديدة ماسكها الـ\nionic bond في بعض\nطب لو two atoms من الـ chlorine قابلوا بعض\nيحصل إيه\nكل واحد محتاج electron كمان فمحدش فيهم\nهيدّي التاني حاجة\nفبيتشاركوا كل واحد يحط electron ويبقى فيه\nزوج electrons في النص\nالرابطة دي اسمها covalent bond يعني الـ\nelectrons متشاركة بين الـ atoms دي\nالـ sodium من نوع اسمه metal والـ metals\nلامعة وبتوصّل الكهربا\nوالـ chlorine نوعه non-metal يعني غالبًا\nمش لامع ومبيوصّلش الكهربا\nومن الـ non-metals كمان الـ oxygen والـ\nhydrogen خلّيهم في بالك\nوغالبًا الـ metal مع الـ non-metal بيعملوا\nionic bond بالنقل\nوالـ non-metals مع بعض غالبًا بيتشاركوا\nفيعملوا covalent bond بينهم\nعندنا الـ magnesium مع الـ oxygen الـ\nchemical bond بينهم نوعه إيه\nأول خطوة الـ magnesium نوعه metal والـ\noxygen نوعه non-metal كده\nتاني خطوة الـ magnesium في الـ outer level\nعنده two والـ oxygen محتاج two\nتالت خطوة الـ magnesium بيدّي الـ oxygen\nالـ two electrons دول\nرابع خطوة الـ magnesium بقى positive ion\nوالـ oxygen بقى negative ion كده\nوالاتنين بيشِدّوا بعض يبقى الرابطة هنا\nionic bond زي الملح بالظبط\nدورك الـ hydrogen مع الـ chlorine بيكوّنوا\nمادة اسمها hydrogen chloride كده\nالرابطة دي ionic bond ولا covalent bond\nوقّف الفيديو وفكّر شوية\nالإجابة covalent bond عشان الـ hydrogen\nوالـ chlorine الاتنين non-metals كده\nمحدش فيهم بيدّي الـ electron خالص\nفبيتشاركوا في زوج electrons بينهم\nطب الكلام ده هيفيدك فين في الباب\nفي الباب هتقابل الـ metallic bond رابطة\nتالتة بين الـ metal atoms وبعضها\nوهتقابل الـ bond breaking والـ bond\nforming يعني روابط بتتكسر وروابط بتتكوّن\nوالاتنين مبنيين على إنك عارف الـ chemical\nbond يعني إيه وده اللي عملناه\nالخلاصة في الـ ionic bond فيه atom بيدّي\nelectrons والتاني بياخدها\nوفي الـ covalent bond الـ atoms بتتشارك في\nأزواج electrons بينها\nيعني الـ ionic بيدّي وياخد والـ covalent\nبيشارك","countable":false,"session_id":"chem-s3-en.ch1.s4","session_no":4,"session_ord":43,"see_also":[{"item_id":"chem-s3-en.lesson-te.high-melting-points","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"High melting and boiling points","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":94.67,"kind":"pause_question","spec":{"answer":"الـ sodium بيدّي الـ electron للـ chlorine: الـ sodium يبقى positive ion، والـ chlorine يبقى negative ion.","prompt":"الـ sodium (2, 8, 1) قابل الـ chlorine (2, 8, 7): الـ electron هيروح فين؟","options":[{"id":"a","text":"الـ sodium بيدّيه للـ chlorine","correct":true},{"id":"b","text":"الـ chlorine بيدّيه للـ sodium","correct":false},{"id":"c","text":"بيتشاركوا فيه","correct":false}],"answer_t_s":98.33,"concept_id":"bond.chemical-bond-basic"},"content_lang":"ar-EG"},{"id":"think-2","t_s":274.16,"kind":"pause_question","spec":{"answer":"covalent bond: الـ hydrogen والـ chlorine الاتنين non-metals، فبيتشاركوا pair من الـ electrons.","prompt":"hydrogen + chlorine → hydrogen chloride: ionic bond ولا covalent bond؟","options":[{"id":"a","text":"covalent bond","correct":true},{"id":"b","text":"ionic bond","correct":false}],"answer_t_s":278.79,"concept_id":"bond.chemical-bond-basic"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-bond.chemical-bond-basic"]},{"id":"chem-s3-en.video-walkthrough-chem.bond-breaking-energy","kind":"walkthrough","version":4,"ord":296,"content_lang":"ar-EG","primary_concept_id":"chem.bond-breaking-energy","concepts":[{"concept_id":"chem.bond-breaking-energy","role":"primary"}],"title":"Bond breaking and bond forming: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.bond-breaking-energy v1 (hook s1: hydrogen burns in chlorine and gives out heat, yet the molecules must first come apart; MCQ options a 'from breaking the bonds' and c 'atoms destroyed and turn into heat' = the two misconceptions refuted in s2, with the en layer's corrections 'bonded atoms hold each other, so pulling them apart needs energy' and 'the same atoms appear in the products, only the bonds change'; s2 FlowDiagram H2 + Cl2 -> separate atoms -> 2HCl, 'Breaking a bond absorbs energy. Forming a bond releases energy.'; s3 made-up 600 kJ absorbed, slider 300–900 kJ released, kJ = kilojoules, a unit of energy, ΔH = absorbed − released, negative = given out, positive = taken in; s4 check 500 / 300; s5 recap). Concept chem.bond-breaking-energy v2 summary; no recorded misconceptions (s2 refutes the lesson's Misconception element + hook options). DB rule chem-s3-en.fact.acids-electrochem: ΔH = absorbed − released (used verbatim on screen). Dependent named in s4 by map title: 'Activation energy and energy profile' (kin.activation-energy; book p.61–62 Ch.3: molecules need enough energy to break bonds; book p.15 fig 1-3 energy profile with net energy released). s4 adds no new facts: no curve, no activation energy definition, no catalyst. Terms (defined at first use, on screen + spoken meaning): s1 energy, atoms, chemical bond (3; 'bond' is the short form of chemical bond); s2 reaction, reactants, products, absorbed, released, kilojoule (kJ), ΔH (energy change); s3/s4 introduce none (s4 chip = dependent concept title; 'bond breaking' / 'bond forming' = this concept's title words, spoken as shown). ΔH is voiced «دلتا إتش» (no lone Latin letter). Worked example: lesson s3 numbers (600 kJ absorbed, 900 kJ released -> ΔH = −300 kJ, gives out). Self-check: NEW made-up case 800 kJ absorbed / 500 kJ released -> ΔH = +300 kJ, takes in (lesson check 500 / 300; the concept's short used 400 / 700). Predicts: s2l8 (~1:20), s3l9 (~4:00). not-in-source: a gas-stove flame gives out heat (everyday anchor); heat and light are kinds of energy; atoms are the tiny particles that matter is made of (prereq concept sci.matter-particles title); a reaction = substances change into new substances (plain meaning); hydrogen and chlorine each have two atoms joined by a bond (lesson shows H2, Cl2 as molecules); a burning (fire) reaction gives out energy; 'energy profile shows the energy before and after the reaction' (dependent summary: reactant and product levels show the net energy change). Estimated duration ≈ 289 s (563 narration words at ~2.4 words/s + 39.0 s pauses + joins); planning aid only.","title":"Bond breaking and bond forming: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"YK.camera pushes in on the burner; the flame grows on cue 'بتولّع'; wavy heat lines (YK.wave ×3, C.amber, alpha 0.6) rise from the flame into the pot on 'حرارة'; YK.tag 'A gas stove flame' (40) under the burner.","tts_text":"لما بتولّع البوتاجاز، النار بتطلّع حرارة تسخّن بيها الأكل.","screen_text":"A gas stove flame","pause_after_s":0.4},{"id":"s1l3","visual":"Two small icons orbit the flame and light up in turn: heat lines on cue 'الحرارة', a light glow (YK.glowCircle, C.gold) on 'والنور'; YK.termCard(ctx, 96, 380, {term: 'energy', def: 'heat and light are kinds of energy', align: 'left', p: on cue 'energy'}).","tts_text":"الحرارة والنور دول أنواع من الـ energy، يعني الطاقة.","screen_text":"energy: heat and light are kinds of energy","pause_after_s":0.4},{"id":"s1l4","visual":"A big gold '?' (ctx paths) appears over the flame on cue 'منين'; YK.fpara 'Where does the energy come from?' (48) in the text panel. Question left open: answered step by step in s2.","tts_text":"طب الـ energy دي جاية منين أصلًا؟ خلّينا نشوف مع بعض.","screen_text":"Where does the energy come from?","pause_after_s":1},{"id":"s1l5","visual":"YK.zoomThrough(ctx, t, {from: drawBurner, to: drawParticles, badge: '×10^8'}) from cue 'الغاز': the gas just above the burner opens into small drifting discs (YK.atomDisc ×10, r 30, symbol: false, grey, YK.swarm motion); YK.scaleBadge in the stage corner. YK.termCard(ctx, 96, 380, {term: 'atoms', def: 'the tiny particles that matter is made of', align: 'left', p: on cue 'atoms'}).","tts_text":"الغاز ده، زي أي مادة، متكوّن من atoms، جسيمات صغيرة جدًا.","screen_text":"atoms: the tiny particles that matter is made of","pause_after_s":0.4},{"id":"s1l6","visual":"The discs pair up; a gold link line (ctx stroke, C.gold, lw 8) draws between the two discs of each pair on cue 'ماسكة' and pulses (YK.pulse) on 'chemical'. YK.termCard(ctx, 96, 380, {term: 'chemical bond', def: 'what holds atoms together', align: 'left', p: on cue 'chemical'}).","tts_text":"والـ atoms دي ماسكة في بعض بالـ chemical bond، يعني رابطة.","screen_text":"chemical bond: what holds atoms together","pause_after_s":0.4},{"id":"s1l7","visual":"Close-up of ONE pair: two YK.atomDisc (r 110, x 1150 / 1470, y 580, symbol: false) with the gold link between them drawn as two short arms meeting in the middle (ctx strokes) on cue 'ماسكين'; YK.tag 'bond' (44) on the link on cue 'bond'.","tts_text":"تخيّل two atoms ماسكين إيدين بعض، وده الـ bond اللي بينهم.","screen_text":"bond = atoms holding each other","pause_after_s":0.4},{"id":"s1l8","visual":"Micro-recap: the three term cards collapse into three YK.chip kind 'concept' in a row in the text panel (96, 300 / 420 / 540) on cues 'energy', 'atoms', 'chemical'; the stage pictures (flame, particle swarm, linked pair) flash in the same order (YK.flashRect).","tts_text":"يبقى معانا تلات كلمات: energy، و atoms، و chemical bond، خلّيهم في بالك.","screen_text":"energy · atoms · chemical bond","pause_after_s":1},{"id":"s2l2","visual":"Stage: a simple left → right strip — a group of grey discs on the left, a gold arrow (YK.formula '->', 64) in the middle, a differently grouped set of discs on the right, building on cues 'مواد'#1 / 'جديدة'. YK.termCard(ctx, 96, 380, {term: 'reaction', def: 'substances change into new substances', align: 'left', p: on cue 'reaction'}).","tts_text":"لما مواد تتغير وتطلع منها مواد جديدة، ده اسمه reaction، أو تفاعل.","screen_text":"reaction: substances change into new substances","pause_after_s":0.4},{"id":"s2l3","visual":"Left side of the strip fills: YK.molecule(ctx, 1000, 520, {atoms: [{el: 'H', x: -0.6, y: 0}, {el: 'H', x: 0.6, y: 0}], bonds: [[0, 1, 1]], r: 50, labels: false}) on cue 'hydrogen' and a Cl–Cl molecule (two YK.atomDisc el 'Cl' r 60 joined by a gold link) at (1000, 760) on cue 'chlorine'; YK.tag 'hydrogen' / 'chlorine' under each; a bracket (YK.bracket) around both with tag 'reactants' on cue 'reactants'. YK.termCard(ctx, 96, 380, {term: 'reactants', def: 'what we start with', align: 'left'}).","tts_text":"الـ hydrogen والـ chlorine اللي بنبدأ بيهم اسمهم reactants، يعني المتفاعلات.","screen_text":"reactants: what we start with · hydrogen + chlorine","pause_after_s":0.4},{"id":"s2l4","visual":"The gold links inside the H–H pair (cue 'hydrogen') and the Cl–Cl pair (cue 'chlorine') pulse (YK.pulse); small '2' counters (mono 40) beside each pair on cue 'two'.","tts_text":"في الـ hydrogen كل two atoms بينهم bond، ونفس الحكاية في الـ chlorine كمان.","screen_text":"hydrogen: 2 atoms with a bond · chlorine: 2 atoms with a bond","pause_after_s":0.4},{"id":"s2l5","visual":"Right side of the strip fills: two H–Cl pairs (YK.atomDisc el 'H' r 40 + el 'Cl' r 60, gold link) at (1620, 520) and (1620, 760) on cue 'hydrogen'; YK.tag 'hydrogen chloride' on cue 'chloride'; YK.bracket with tag 'products' on cue 'products'. YK.termCard(ctx, 96, 380, {term: 'products', def: 'what we end with', align: 'left'}).","tts_text":"واللي بيطلع في الآخر hydrogen chloride، واسمه products، يعني النواتج.","screen_text":"products: what we end with · hydrogen chloride","pause_after_s":0.4},{"id":"s2l6","visual":"Heat lines (YK.wave ×3, C.amber) rise from the arrow of the strip on cue 'حرارة'; a mint arrow pointing out of the strip with tag 'energy out' (40, mint) on cue 'energy'.","tts_text":"والـ reaction ده بيطلّع حرارة، يعني energy طالعة برّه.","screen_text":"This reaction gives out heat: energy out","pause_after_s":0.4},{"id":"s2l7","visual":"New picture (strip shrinks to the top of the stage, alpha 0.35): the H–H and Cl–Cl molecules in the centre stretch (YK.molecule stretch 0 → 1 on cue 'تتكسر' for H–H; the Cl–Cl link thins and dashes the same way) and come apart into four separate YK.atomDisc on 'تتفصل'. Text panel YK.list item 'Step 1: the old bonds break' (44).","tts_text":"أول خطوة: الـ bonds اللي في الـ reactants لازم تتكسر، والـ atoms تتفصل.","screen_text":"Step 1: the old bonds break → separate atoms","pause_after_s":0.4},{"id":"s2l8","visual":"YK.predictCard(ctx, t, {at: YK.cueX('s2l8','توقّع'), until: YK.cue('s2l9') + 0.4, think: YK.cueEnd('s2l8'), end: YK.cue('s2l9'), kind: 'PREDICT', q: 'Breaking a bond: energy in or energy out?'}); stage: ONE H–H pair close-up (two YK.atomDisc el 'H' r 100, gold link) frozen just before it snaps. Nothing answered during the 3 s silence.","tts_text":"توقّع: كسر الـ bond ده بياخد energy ولا بيطلّع energy؟ فكّر.","screen_text":"PREDICT: breaking a bond: energy in or energy out?","pause_after_s":3},{"id":"s2l9","visual":"Answer: a coral arrow points INTO the bond (ctx path, C.coral, lw 10) on cue 'بياخد' and the link snaps (gap opens, short spark) on 'نشدها'; YK.answerSlot(ctx, t, {at: YK.cue('s2l9','بياخد'), text: 'Breaking a bond: energy in', x: 420, y: 760}).","tts_text":"كسر الـ bond بياخد energy، لأن الـ atoms ماسكة في بعض ولازم نشِدّها.","screen_text":"Breaking a bond: energy in","pause_after_s":0.4},{"id":"s2l10","visual":"Misconception (lesson s2 Misconception + hook option a): YK.mythLine(ctx, t, {at: YK.cue('s2l10'), wrongAt: YK.cueX('s2l10','غلط'), until: YK.cueEnd('s2l11') + 1.5, text: 'Breaking bonds gives energy out', x: 96, y: 300, size: 44}) — coral text with ✕ (YK.wrongMark) from the «غلط» cue for its whole visible time, no strike-through. Stage: a faint outward arrow on the snapping bond, crossed by YK.wrongMark(ctx, 1310, 460, 100) on the same cue.","tts_text":"فيه ناس فاكرة إن كسر الـ bonds هو اللي بيطلّع الـ energy، وده غلط.","screen_text":"Breaking bonds gives energy out ✕","pause_after_s":0.4},{"id":"s2l11","visual":"Fix (held ≥ the myth): the two discs get the 'arms' of s1l7 again; they are pulled apart against the hold (YK.tween, slow then sudden) on cue 'تشد'; the coral inward arrow returns larger + YK.rightMark next to 'Pulling held hands apart takes effort' (YK.fpara 44, mint, 96, 420) on cue 'مجهود'. The myth line and its ✕ stay above.","tts_text":"زي ما تفُكّ إيدين ماسكين في بعض، لازم تشِدّ، وده عايز مجهود.","screen_text":"Pulling held hands apart takes effort ✓","pause_after_s":0.4},{"id":"s2l12","visual":"The coral inward arrow pulses; YK.termCard(ctx, 96, 380, {term: 'absorbed', def: 'taken in', align: 'left', accent: C.coral, p: on cue 'absorbed'}); YK.tag 'energy absorbed' (40, coral) at the arrow on the same cue.","tts_text":"وبنقول إن الـ energy هنا absorbed، يعني اتسحبت لجوه.","screen_text":"absorbed: taken in","pause_after_s":0.4},{"id":"s2l13","visual":"The four separate atoms regroup into two H–Cl pairs (YK.atomDisc H + Cl, gold links drawing on cue 'تتكوّن'); text panel YK.list item 'Step 2: new bonds form' (44). Same atoms as before: each disc keeps its symbol.","tts_text":"وبعدين الـ atoms تتجمع بشكل جديد، و bonds جديدة تتكوّن.","screen_text":"Step 2: new bonds form","pause_after_s":0.4},{"id":"s2l14","visual":"A mint arrow points OUT of a newly formed H–Cl link with a small flash (YK.glowCircle, C.mint) on cue 'بيطلّع'; YK.termCard(ctx, 96, 380, {term: 'released', def: 'given out', align: 'left', accent: C.mint, p: on cue 'released'}); YK.tag 'energy released' (40, mint).","tts_text":"وتكوين الـ bond بيطلّع energy برّه، وبنقول عليها released كده.","screen_text":"released: given out","pause_after_s":0.4},{"id":"s2l15","visual":"Second misconception (lesson hook option c): a ghost picture of the discs fading into heat lines, YK.mythLine(ctx, t, {at: YK.cue('s2l15'), wrongAt: YK.cueX('s2l15','غلط'), until: YK.cueEnd('s2l16') + 1.5, text: 'The atoms are destroyed and turn into heat', x: 96, y: 300, size: 44}) with ✕ for its whole visible time, no strike-through.","tts_text":"وفيه ناس فاكرة إن الـ atoms نفسها بتختفي وتتحول لحرارة، وده غلط.","screen_text":"The atoms are destroyed and turn into heat ✕","pause_after_s":0.4},{"id":"s2l16","visual":"Fix: the strip of s2l2 returns full size; each atom on the left gets a thin gold thread to the same atom on the right (2 H, 2 Cl) on cue 'نفس'; links on both sides flash on 'الـ bonds'. YK.rightMark + 'Same atoms before and after: only the bonds change' (YK.fpara 44, mint, 96, 420). Lesson feedback c wording.","tts_text":"نفس الـ atoms موجودة قبل وبعد، اللي بيتغير هو الـ bonds بينهم.","screen_text":"Same atoms before and after: only the bonds change ✓","pause_after_s":0.4},{"id":"s2l17","visual":"New picture: YK.balance(ctx, 1307, 640, 720, {left: 'energy in', right: 'energy out', value: 0, leftColor: C.coral, rightColor: C.mint}) appears on cue 'energy'#1; the left pan glows on 'داخلة', the right pan on 'طالعة'.","tts_text":"يبقى عندنا energy داخلة في الكسر، و energy طالعة في التكوين.","screen_text":"energy in vs energy out","pause_after_s":0.4},{"id":"s2l18","visual":"The balance tips right (value 0 → 0.6) on cue 'أكتر'; the s1 flame returns small beside the right pan on 'النار'; YK.fpara 'out > in → the reaction gives out energy' (44) in the text panel.","tts_text":"لو الطالع أكتر من الداخل، الـ reaction بيطلّع energy زيادة، زي النار.","screen_text":"out > in → the reaction gives out energy","pause_after_s":0.4},{"id":"s2l19","visual":"The balance swings back and tips left (value 0.6 → −0.6) on cue 'أكتر'; flame thumbnail fades; YK.fpara 'in > out → the reaction takes in energy' (44) under the first rule.","tts_text":"ولو الداخل أكتر من الطالع، الـ reaction بياخد energy في الآخر.","screen_text":"in > out → the reaction takes in energy","pause_after_s":0.4},{"id":"s2l20","visual":"Back to the hook (lesson s1 answer): the H2 + Cl2 → HCl strip returns; the balance under it tips right on cue 'أكتر'; heat lines rise on the same cue; YK.rightMark small next to the strip.","tts_text":"وده اللي بيحصل في الـ hydrogen والـ chlorine: التكوين بيطلّع أكتر من الكسر.","screen_text":"Hydrogen + chlorine: more energy out than in","pause_after_s":0.6},{"id":"s2l21","visual":"New picture: the two balance pans get number slots (empty, dashed); YK.termCard(ctx, 96, 380, {term: 'kilojoule (kJ)', def: 'a unit of energy', align: 'left', p: on cue 'kilojoule'}); a small ruler drawn with ctx paths beside the term on cue 'بالمتر' (comparison only).","tts_text":"وبنقيس الـ energy بوحدة اسمها kilojoule، زي ما بنقيس المسافة بالمتر.","screen_text":"kilojoule (kJ): a unit of energy","pause_after_s":0.4},{"id":"s2l22","visual":"YK.formula(ctx, 'ΔH = absorbed - released', 1307, 420, {size: 64, align: 'center', reveal: from cue 'delta' to cue 'released'}) with 'absorbed' in coral and 'released' in mint (same colours as the arrows); YK.termCard(ctx, 96, 380, {term: 'ΔH (energy change)', def: 'absorbed − released', align: 'left', p: on cue 'energy'}).","tts_text":"والفرق بينهم اسمه energy change، ونكتبه delta H: الـ absorbed minus الـ released كده.","screen_text":"ΔH (energy change) = absorbed − released","pause_after_s":0.6},{"id":"s2l23","visual":"Under the formula: a minus sign badge (ctx text, mono 72, C.mint) on cue 'negative' with the mint outward arrow and tag 'energy given out' (40) on 'بيطلّع'; the balance below tips right.","tts_text":"لو delta H طلع negative، يبقى الـ reaction بيطلّع energy برّه.","screen_text":"ΔH −  → energy given out","pause_after_s":0.4},{"id":"s2l24","visual":"A plus sign badge (mono 72, C.coral) on cue 'positive' with the coral inward arrow and tag 'energy taken in' (40) on 'بياخد'; the balance tips left.","tts_text":"ولو طلع positive، يبقى الـ reaction بياخد energy جوه.","screen_text":"ΔH +  → energy taken in","pause_after_s":1},{"id":"s3l2","visual":"Stage: the balance of s2l17 (YK.balance, value 0); the left pan gets '600 kJ' (YK.formula mono 56, coral) on cue 'six'; tag 'made-up numbers' (32, textDim) above the balance on cue 'للتمرين'. Lesson s3 value (600 kJ absorbed). Worked steps stack in the text panel (YK.list, LTR).","tts_text":"عندنا reaction بأرقام للتمرين: الـ absorbed في الكسر six hundred kilojoules كده.","screen_text":"A reaction (made-up numbers): absorbed = 600 kJ","pause_after_s":0.4},{"id":"s3l3","visual":"The right pan gets '900 kJ' (mono 56, mint) on cue 'nine'; the balance tips right (value 0 → 0.5) on 'أكتر'. Lesson s3 slider maximum.","tts_text":"والـ released في التكوين nine hundred kilojoules، يعني الطالع أكتر.","screen_text":"released = 900 kJ","pause_after_s":0.4},{"id":"s3l4","visual":"YK.list item 1: YK.formula 'ΔH = absorbed - released' (48) builds on cues 'delta' / 'absorbed' / 'released' (colours as in s2l22).","tts_text":"أول خطوة: نكتب delta H equals الـ absorbed minus الـ released، زي ما قلنا.","screen_text":"Step 1: ΔH = absorbed − released","pause_after_s":0.4},{"id":"s3l5","visual":"YK.list item 2: YK.formula 'ΔH = 600 - 900' (48); '600' flies from the left pan (YK.flyer) on cue 'six', '900' from the right pan on 'minus'.","tts_text":"تاني خطوة: نعوّض بالأرقام، six hundred minus nine hundred كده.","screen_text":"Step 2: ΔH = 600 − 900","pause_after_s":0.4},{"id":"s3l6","visual":"YK.list item 3: YK.formula 'ΔH = -300 kJ' (56) on cue 'three'; the minus sign flashes gold (YK.flashRect) on 'والإشارة'.","tts_text":"تالت خطوة: الناتج minus three hundred kilojoules، والإشارة negative هنا.","screen_text":"Step 3: ΔH = −300 kJ","pause_after_s":0.4},{"id":"s3l7","visual":"Mint outward arrow from the balance with tag 'gives out 300 kJ' (44) on cue 'بيطلّع'; YK.rightMark; the s1 flame thumbnail flashes beside it on 'النار'.","tts_text":"يعني الـ reaction ده بيطلّع three hundred kilojoules برّه، زي النار.","screen_text":"ΔH −  → the reaction gives out 300 kJ ✓","pause_after_s":1},{"id":"s3l8","visual":"Self-check on a NEW case (made-up numbers; the lesson check used 500 / 300 and the worked example 600 / 900): stage clears to a fresh YK.balance with '800 kJ' (coral) on the left pan on cue 'eight' and '500 kJ' (mint) on the right on 'five'; the beam stays level and inert (no tilt claim). YK.predictCard(ctx, t, {at: YK.cue('s3l8'), until: YK.cue('s3l10') + 0.4, think: YK.cueEnd('s3l9'), end: YK.cue('s3l10'), kind: 'QUICK CHECK', q: '800 kJ in, 500 kJ out: ΔH? Gives out or takes in?'}).","tts_text":"دورك: الكسر بياخد eight hundred kilojoules، والتكوين بيطلّع five hundred kilojoules كده.","screen_text":"Your turn: 800 kJ in, 500 kJ out","pause_after_s":0.4},{"id":"s3l9","visual":"The question stays; YK.checkPause(ctx, 1307, 880, {t, start: YK.cueEnd('s3l9'), dur: 4}) think ring + countdown through the silence; only the question shows (no answer, no hint) during the pause.","tts_text":"احسب delta H: الـ reaction بيطلّع ولا بياخد energy؟ وقّف الفيديو وفكّر.","screen_text":"ΔH = ? Gives out or takes in?","pause_after_s":4},{"id":"s3l10","visual":"Answer: YK.formula 'ΔH = 800 - 500 = +300 kJ' (56) builds on cues 'eight' / 'minus' / 'equals'; YK.answerSlot(ctx, t, {at: YK.cue('s3l10','equals'), text: 'ΔH = +300 kJ', x: 420, y: 700}).","tts_text":"الحل: eight hundred minus five hundred equals plus three hundred kilojoules كده.","screen_text":"ΔH = 800 − 500 = +300 kJ","pause_after_s":0.4},{"id":"s3l11","visual":"Reason: the balance now tips left (value 0 → −0.5) on cue 'أكتر'; coral inward arrow with tag 'takes in 300 kJ' (44) on 'بياخد'; YK.rightMark.","tts_text":"يعني positive: الكسر أخد أكتر من اللي التكوين طلّعه، فالـ reaction بياخد energy جوه.","screen_text":"ΔH +  → the reaction takes in 300 kJ ✓","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الباب؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, 'Activation energy and energy profile', {kind: 'concept', align: 'left'}) (map title exactly) on cue 'activation'; the words 'Activation energy' and 'energy profile' in the chip pulse gold on their cues; a thin gold line from the chip down to a small chip 'Bond breaking and bond forming' (YK.chip kind 'concept', 96, 520) on cue 'اتعلمناه'.","tts_text":"في الباب هتقابل الـ activation energy والـ energy profile، والاتنين محتاجين اللي اتعلمناه ده.","screen_text":"Activation energy and energy profile","pause_after_s":0.4},{"id":"s4l3","visual":"Under the chip: a small replay of the s2l7 bond snapping with the coral inward arrow on cue 'كسر' (no curve, no numbers, no definition — that is the chapter's lesson); YK.tag 'bond breaking needs energy in' (36) on cue 'محتاج'.","tts_text":"الـ activation energy بيستخدم فكرة إن كسر الـ bonds محتاج energy الأول.","screen_text":"Activation energy uses: bond breaking needs energy in","pause_after_s":0.4},{"id":"s4l3a","visual":"Under it: two short horizontal level lines only (left 'before', right 'after', ctx strokes, no hump and no axis values) on cues 'قبل' / 'وبعد'; a small vertical double arrow between them with 'ΔH' (YK.formula 40) on cue 'delta'. The curve itself is the chapter's lesson.","tts_text":"والـ energy profile بيورّيك الـ energy قبل وبعد، والفرق هو delta H بالظبط.","screen_text":"Energy profile uses: energy before vs after (ΔH)","pause_after_s":0.6},{"id":"s4l4","visual":"Recap (s4l4–s4l6 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l4'), until: YK.cue('s4l6'), title: 'Bond breaking and bond forming', line: 'Bond breaking: energy absorbed', pulse: [{word: 'absorbed', at: YK.cueX('s4l4','absorbed')}]}); stage: the snapping bond with the coral inward arrow replays small.","tts_text":"الخلاصة: في الـ bond breaking، الـ energy بتبقى absorbed، داخلة جوه.","screen_text":"Bond breaking: energy absorbed","pause_after_s":0.4},{"id":"s4l5","visual":"Same recap card, second line 'Bond forming: energy released' on cue 'forming' and third line YK.formula 'ΔH = absorbed - released' (40) on cue 'دلتا'; stage: a link forming with the mint outward arrow.","tts_text":"وفي الـ bond forming بتبقى released، و delta H هو absorbed minus released كده.","screen_text":"Bond forming: energy released · ΔH = absorbed − released","pause_after_s":0.6},{"id":"s4l6","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Bond breaking and bond forming', line: 'Bond breaking: energy in. Bond forming: energy out.', t, pulse: [{word: 'in', at: YK.cueX('s4l6','بياخد')}, {word: 'out', at: YK.cueX('s4l6','بيطلّعها')}]}) held ≥ 2.5 s; no fade to black, no outro.","tts_text":"يعني الـ bond breaking بياخد energy، والـ bond forming بيطلّعها.","screen_text":"Bond breaking: energy in. Bond forming: energy out.","pause_after_s":1.5}],"logline":"هتعرف إن أي reaction فيه bonds بتتكسر وبتاخد energy، و bonds بتتكوّن وبتطلّع energy، وتحسب دلتا إتش وتعرف الـ reaction بيطلّع ولا بياخد energy.","segments":[{"id":"s1","title":"A gas flame: where does its energy come from?","concept_id":"chem.bond-breaking-energy"},{"id":"s2","title":"Breaking and forming bonds","concept_id":"chem.bond-breaking-energy"},{"id":"s3","title":"Finding delta H of a reaction","concept_id":"chem.bond-breaking-energy"},{"id":"s4","title":"Where Chapter 1 uses bond 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بتولّع البوتاجاز النار بتطلّع حرارة\nتسخّن بيها الأكل\nالحرارة والنور دول أنواع من الـ energy\nيعني الطاقة\nطب الـ energy دي جاية منين أصلًا خلّينا\nنشوف مع بعض\nالغاز ده زي أي مادة متكوّن من atoms جسيمات\nصغيرة جدًا\nوالـ atoms دي ماسكة في بعض بالـ chemical\nbond يعني رابطة\nتخيّل two atoms ماسكين إيدين بعض وده الـ\nbond اللي بينهم\nيبقى معانا تلات كلمات energy و atoms و\nchemical bond خلّيهم في بالك\nلما مواد تتغير وتطلع منها مواد جديدة ده\nاسمه reaction أو تفاعل\nالـ hydrogen والـ chlorine اللي بنبدأ بيهم\nاسمهم reactants يعني المتفاعلات\nفي الـ hydrogen كل two atoms بينهم bond\nونفس الحكاية في الـ chlorine كمان\nواللي بيطلع في الآخر hydrogen chloride\nواسمه products يعني النواتج\nوالـ reaction ده بيطلّع حرارة يعني energy\nطالعة برّه\nأول خطوة الـ bonds اللي في الـ reactants\nلازم تتكسر والـ atoms تتفصل\nتوقّع كسر الـ bond ده بياخد energy ولا\nبيطلّع energy فكّر\nكسر الـ bond بياخد energy لأن الـ atoms\nماسكة في بعض ولازم نشِدّها\nفيه ناس فاكرة إن كسر الـ bonds هو اللي\nبيطلّع الـ energy وده غلط\nزي ما تفُك إيدين ماسكين في بعض لازم تشِد\nوده عايز مجهود\nوبنقول إن الـ energy هنا absorbed يعني\nاتسحبت لجوه\nوبعدين الـ atoms تتجمع بشكل جديد و bonds\nجديدة تتكوّن\nوتكوين الـ bond بيطلّع energy برّه وبنقول\nعليها released كده\nوفيه ناس فاكرة إن الـ atoms نفسها بتختفي\nوتتحول لحرارة وده غلط\nنفس الـ atoms موجودة قبل وبعد اللي بيتغير\nهو الـ bonds بينهم\nيبقى عندنا energy داخلة في الكسر و energy\nطالعة في التكوين\nلو الطالع أكتر من الداخل الـ reaction\nبيطلّع energy زيادة زي النار\nولو الداخل أكتر من الطالع الـ reaction\nبياخد energy في الآخر\nوده اللي بيحصل في الـ hydrogen والـ\nchlorine التكوين بيطلّع أكتر من الكسر\nوبنقيس الـ energy بوحدة اسمها kilojoule زي\nما بنقيس المسافة بالمتر\nوالفرق بينهم اسمه energy change ونكتبه\ndelta H الـ absorbed minus الـ released\nكده\nلو delta H طلع negative يبقى الـ reaction\nبيطلّع energy برّه\nولو طلع positive يبقى الـ reaction بياخد\nenergy جوه\nعندنا reaction بأرقام للتمرين الـ absorbed\nفي الكسر six hundred kilojoules كده\nوالـ released في التكوين nine hundred\nkilojoules يعني الطالع أكتر\nأول خطوة نكتب delta H equals الـ absorbed\nminus الـ released زي ما قلنا\nتاني خطوة نعوّض بالأرقام six hundred minus\nnine hundred كده\nتالت خطوة الناتج minus three hundred\nkilojoules والإشارة negative هنا\nيعني الـ reaction ده بيطلّع three hundred\nkilojoules برّه زي النار\nدورك الكسر بياخد eight hundred kilojoules\nوالتكوين بيطلّع five hundred kilojoules\nكده\nاحسب delta H الـ reaction بيطلّع ولا بياخد\nenergy وقّف الفيديو وفكّر\nالحل eight hundred minus five hundred\nequals plus three hundred kilojoules كده\nيعني positive الكسر أخد أكتر من اللي\nالتكوين طلّعه فالـ reaction بياخد energy\nجوه\nطب الكلام ده هيفيدك فين في الباب\nفي الباب هتقابل الـ activation energy والـ\nenergy profile والاتنين محتاجين اللي\nاتعلمناه ده\nالـ activation energy بيستخدم فكرة إن كسر\nالـ bonds محتاج energy الأول\nوالـ energy profile بيورّيك الـ energy قبل\nوبعد والفرق هو delta H بالظبط\nالخلاصة في الـ bond breaking الـ energy\nبتبقى absorbed داخلة جوه\nوفي الـ bond forming بتبقى released و\ndelta H هو absorbed minus released كده\nيعني الـ bond breaking بياخد energy والـ\nbond forming بيطلّعها","countable":false,"session_id":"chem-s3-en.ch1.s5","session_no":5,"session_ord":42,"see_also":[{"item_id":"chem-s3-en.lesson-te.catalytic-activity","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Catalytic activity of transition elements","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":78.5,"kind":"pause_question","spec":{"answer":"energy in: الـ atoms ماسكة في بعض، وفصلها محتاج energy.","prompt":"كسر الـ bond: energy in ولا energy out؟","options":[{"id":"a","text":"energy in","correct":true},{"id":"b","text":"energy out","correct":false}],"answer_t_s":82.02,"concept_id":"chem.bond-breaking-energy"},"content_lang":"ar-EG"},{"id":"think-2","t_s":217.23,"kind":"pause_question","spec":{"answer":"ΔH = absorbed − released = 800 − 500 = +300 kJ؛ ΔH موجب يعني الـ reaction بياخد energy.","prompt":"800 kJ in و 500 kJ out: الـ ΔH كام؟ والـ reaction بيطلّع ولا بياخد energy؟","options":[{"id":"a","text":"+300 kJ، بياخد energy","correct":true},{"id":"b","text":"−300 kJ، بيطلّع energy","correct":false},{"id":"c","text":"+1300 kJ، بياخد energy","correct":false}],"answer_t_s":221.86,"concept_id":"chem.bond-breaking-energy"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.bond-breaking-energy"]},{"id":"chem-s3-en.video-walkthrough-chem.elements-compounds-mixtures","kind":"walkthrough","version":4,"ord":337,"content_lang":"ar-EG","primary_concept_id":"chem.elements-compounds-mixtures","concepts":[{"concept_id":"chem.elements-compounds-mixtures","role":"primary"}],"title":"Elements, compounds and mixtures: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.elements-compounds-mixtures v1 (hook s1: grey iron filings + yellow sulphur powder, a magnet pulls the iron out; heat a fresh mixture strongly, a black solid forms; predict: can the magnet still pull the iron out — answer no, iron(II) sulphide FeS (en layer); s2 'An element has one kind of atom', KeyTerm 'Compound' verbatim, 'FeS is black: not grey like iron, not yellow like sulphur. It always has 1 Fe for 1 S'; s3 KeyTerm 'Mixture' verbatim, Misconception 'A mixture and a compound are the same thing' + correction, DataTable ratio / properties / separation rows; s4 sort item 'Salt water' (feedback: more or less salt, ratio not fixed) = worked example; Fe2O3-in-sand rock question = the s4 ore picture; s5 'Next: iron is found in ores: iron compounds, mostly oxides, mixed with impurities (unwanted substances)'). Concept v2 misconception chem.elements-compounds-mixtures.mc1 refuted in s2l18–s2l21 (✕ held through the three ✓ rows). Prereq chem.elements-symbols summary (element = one kind of atom). Dependents named in s4 (in-book, map titles): 'Iron: abundance and suitability of iron ore' (fe.occurrence; book p.16: ores = iron oxides mixed with impurities, worded per DB rule chem-s3-en.ch1.fact.iron-ore-wording 'iron compounds (mostly oxides)'), 'Alloys: definition and preparation' (book p.19); no alloy facts given. Not named: chem.mixture-separation, chem.solution-concentration (in_book=false). Terms (defined at first use, on screen + spoken meaning): s1 atoms, element, properties (3); s2 Mixture, physical means, fixed ratio, Compound (+ the name iron(II) sulphide with a one-line gloss of '(II)'). s3 introduces none; s4 glosses 'iron ores' (الخامات), 'oxides' (iron joined with oxygen), 'impurities' (unwanted substances, lesson wording) and 'alloys' (السبايك) as parts of the dependent titles. 'magnet' is an object label, spoken as shown. Voicing: 'iron اتنين sulphide' (3-word compound name with an Arabic numeral, chem-s3-en.voice.groups-configs). Book spelling 'sulphur'. Worked example: salt water (lesson s4 item) -> mixture. Self-check: NEW case table salt (sodium chloride) -> compound (not in this lesson's sort list; the concept short used MgO). Predicts: s2l9 (~2:05), s3l10 (~4:30). not-in-source: koshari is rice, lentils and pasta stirred together and its parts can be picked out (everyday anchor); atoms are the tiny particles matter is made of (prereq sci.matter-particles title); a magnet does not pull sulphur; physical means = separating without making a new substance; FeS is not pulled by a magnet (lesson: the magnet cannot pull the iron out); boiling the water away leaves the salt (physical separation); table salt is sodium chloride, a compound of sodium and chlorine (lesson bond.chemical-bond-basic hook: soft reactive metal + poisonous gas -> table salt); intermetallic/alloy distinction left to the chapter. Estimated duration ≈ 309 s (609 narration words at ~2.4 words/s + 39.8 s pauses + joins); planning aid only.","title":"Elements, compounds and mixtures: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"YK.camera pushes in on the plate; the three kinds glow in turn on cues 'رز' / 'وعدس' / 'ومكرونة' (YK.glowCircle around one grain of each); YK.formula 'rice + lentils + pasta' (44) in the text panel builds on the same cues.","tts_text":"بص على طبَق كشري: رز وعدس ومكرونة متقلبين على بعض.","screen_text":"rice + lentils + pasta","pause_after_s":0.4},{"id":"s1l3","visual":"A spoon (ctx path, C.steel) dips in and lifts out only lentils on cue 'تطلّع'; the rice and pasta stay unchanged on 'زي'; YK.fpara 'Each part stays as it is' (44). This picture returns in s2 as the mixture callback.","tts_text":"وتقدر تطلّع العدس بالمعلقة، وكل حاجة فيه فاضلة زي ما هي.","screen_text":"Each part stays as it is","pause_after_s":0.4},{"id":"s1l4","visual":"New picture: a heap of grey iron filings (thin ctx strokes, C.steel) on the stage; YK.zoomThrough(ctx, t, {from: drawFilings, to: drawAtoms, badge: '×10^8'}) from cue 'جسيمات' into a neat grid of identical grey YK.atomDisc (r 36, symbol: false); YK.scaleBadge in the corner. YK.termCard(ctx, 96, 380, {term: 'atoms', def: 'the tiny particles that matter is made of', align: 'left', p: on cue 'atoms'}).","tts_text":"وأي مادة حوالينا متكوّنة من atoms، يعني جسيمات صغيرة جدًا.","screen_text":"atoms: the tiny particles that matter is made of","pause_after_s":0.4},{"id":"s1l5","visual":"All discs of the grid pulse together (same colour, same size) on cue 'واحد'; YK.termCard(ctx, 96, 380, {term: 'element', def: 'a substance made of one kind of atom', align: 'left', p: on cue 'element'}).","tts_text":"المادة اللي فيها نوع واحد من الـ atoms اسمها element كده.","screen_text":"element: a substance made of one kind of atom","pause_after_s":0.4},{"id":"s1l6","visual":"Zoom back out to the grey filings (YK.zoomThrough reversed) on cue 'برادة'; YK.tag 'iron' (44) on cue 'iron'; the atom grid stays as a small inset (YK.panel 1420, 200, 360, 260) with tag 'one kind of atom' on cue 'واحد'.","tts_text":"زي برادة الـ iron الرمادي دي، كلها atoms من نوع واحد.","screen_text":"iron: one kind of atom (grey filings)","pause_after_s":0.4},{"id":"s1l7","visual":"A heap of yellow sulphur powder (YK.dot ×60, pale yellow, YK.rng(11)) pops in beside the iron on cue 'sulphur'; its inset grid shows yellow discs (YK.atomDisc symbol: false) on 'تاني'#2; YK.tag 'sulphur' (44). Book spelling 'sulphur'.","tts_text":"والـ sulphur البودرة الصفرا دي element تاني، بنوع atoms تاني.","screen_text":"sulphur: an element (yellow powder)","pause_after_s":0.4},{"id":"s1l8","visual":"YK.termCard(ctx, 96, 380, {term: 'properties', def: 'what a substance is like (colour, does a magnet pull it?)', align: 'left', p: on cue 'properties'}); stage: colour swatches 'grey' / 'yellow' (YK.tag 36) under the two heaps on cue 'لونها'; a horseshoe YK.magnet(ctx, 1300, 300, {type: 'horseshoe', size: 220, field: 0}) appears above them on cue 'magnet'.","tts_text":"وكل مادة ليها properties، يعني صفاتها: لونها، والـ magnet بيشِدّها ولا لأ.","screen_text":"properties: what a substance is like (colour, does a magnet pull it?)","pause_after_s":0.4},{"id":"s1l9","visual":"The magnet moves over the iron heap and filings jump up to it (short YK.flyer arcs, trail) on cue 'بيشد'#1; it moves over the sulphur and nothing moves on 'مش'; YK.tag 'magnet: pulls iron' and 'does not pull sulphur' (36) on the same cues.","tts_text":"الـ magnet بيشِدّ الـ iron، إنما مش بيشِدّ الـ sulphur خالص.","screen_text":"magnet: pulls iron · does not pull sulphur","pause_after_s":0.4},{"id":"s1l10","visual":"Micro-recap: the three term cards collapse into three YK.chip kind 'concept' in a row in the text panel (96, 300 / 420 / 540) on cues 'atoms', 'element', 'properties'; the stage pictures (atom grid, iron and sulphur heaps, magnet) flash in the same order (YK.flashRect).","tts_text":"يبقى معانا تلات كلمات: atoms، و element، و properties، خلّيهم في بالك.","screen_text":"atoms · element · properties","pause_after_s":1},{"id":"s2l2","visual":"Stage: the two heaps slide into one dish (ctx ellipse) on cue 'نخلط' and are stirred (positions tween from two piles to one even spread, YK.rng(13)) on 'ونقلّبهم'; YK.tag 'iron' / 'sulphur' on their cues; YK.fpara 'iron + sulphur, stirred together' (44).","tts_text":"نخلط برادة الـ iron مع بودرة الـ sulphur، ونقلّبهم كويس.","screen_text":"iron + sulphur, stirred together","pause_after_s":0.4},{"id":"s2l3","visual":"Zoom inset (YK.panel 1180, 200, 600, 340): grey and yellow discs sit side by side, NOT linked (no lines between them) on cue 'حبيبات'; swatches 'grey' / 'yellow' pulse on 'رمادي' / 'صفرا'; tag 'properties' on cue 'properties'.","tts_text":"تبص تلاقي حبيبات رمادي وحبيبات صفرا، كل واحدة فاضل ليها نفس الـ properties بتاعتها.","screen_text":"grey bits + yellow bits: each keeps its properties","pause_after_s":0.4},{"id":"s2l4","visual":"The magnet sweeps over the dish on cue 'قرّبت'; grey filings ride up to it (YK.flyer ×12, trails) on 'يشد'; yellow powder stays in the dish on 'ويسيب'.","tts_text":"ولو قرّبت الـ magnet، يشِدّ الـ iron لوحده ويسيب الـ sulphur مكانه.","screen_text":"A magnet pulls the iron out","pause_after_s":0.4},{"id":"s2l5","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 340, {term: 'Mixture', def: 'Two or more substances mixed physically. Each keeps its own properties, and they can be separated by physical means.', keys: ['mixed physically', 'keeps its own properties'], align: 'left', p: on cue 'mixture'}); stage: the s1 rice plate returns small in the corner on 'متخلطة' (callback).","tts_text":"ده اسمه mixture: مواد متخلطة ببعض، وكل مادة فاضلة زي ما هي.","screen_text":"Mixture: Two or more substances mixed physically. Each keeps its own properties, and they can be separated by physical means.","pause_after_s":0.6},{"id":"s2l6","visual":"The definition card's key 'physical means' highlights gold on cue 'physical'; stage: small icons YK.icon('magnet') and a filter funnel (ctx path) pop in on 'بنفصل'; YK.tag 'physical means' (40).","tts_text":"والـ magnet ده physical means، يعني بنفصل من غير ما نعمل مادة جديدة.","screen_text":"physical means: separating without making a new substance (a magnet, a filter)","pause_after_s":0.4},{"id":"s2l7","visual":"New picture: a fresh grey + yellow dish on a burner flame (ctx flame, C.amber; YK.glowCircle under the dish) on cue 'ونسخّنه'; tags 'iron' / 'sulphur' on cues; YK.fpara 'Heat a fresh iron + sulphur mixture strongly' (40).","tts_text":"طب نجيب mixture جديد من الـ iron والـ sulphur، ونسخّنه جامد.","screen_text":"Heat a fresh iron + sulphur mixture strongly","pause_after_s":0.4},{"id":"s2l8","visual":"The dish contents darken to one black lump (colour tween grey/yellow → #1A1A1A) on cue 'التسخين'; YK.tag 'black solid' (40) on 'أسود'; flame off.","tts_text":"وبعد التسخين، بيطلع جسم صُلب لونه أسود خالص.","screen_text":"A black solid forms","pause_after_s":0.4},{"id":"s2l9","visual":"YK.predictCard(ctx, t, {at: YK.cueX('s2l9','توقّع'), until: YK.cue('s2l10') + 0.4, think: YK.cueEnd('s2l9'), end: YK.cue('s2l10'), kind: 'PREDICT', q: 'Can the magnet still pull the iron out of the black solid?'}); stage: the magnet hovers over the black lump, still. Nothing answered during the 3 s silence (lesson hook).","tts_text":"توقّع: الـ magnet هيقدر يشِدّ الـ iron من الجسم الأسود ده؟ فكّر.","screen_text":"PREDICT: can the magnet still pull the iron out of the black solid?","pause_after_s":3},{"id":"s2l10","visual":"Answer: the magnet passes over the lump and nothing moves on cue 'لأ'; YK.answerSlot(ctx, t, {at: YK.cue('s2l10','لأ'), text: 'No: the magnet cannot pull the iron out', x: 420, y: 760}); a small grey disc glimmers inside the lump on 'جوه' (the iron atoms are still there).","tts_text":"لأ، الـ magnet مش هيشِدّ حاجة، مع إن الـ iron لسه جوه.","screen_text":"No: the magnet cannot pull the iron out","pause_after_s":0.4},{"id":"s2l11","visual":"Zoom inset into the lump: grey and yellow discs now in a neat alternating grid, each grey disc joined to a yellow one by a short white link (YK.atomDisc el 'Fe' / 'S', links on cue 'ماسكة'); contrast with the unlinked mixture inset of s2l3 shown small beside it.","tts_text":"عشان الـ iron والـ sulphur اتّحدوا كيميائيًا، والـ atoms بقت ماسكة في بعض.","screen_text":"iron and sulphur atoms now hold each other","pause_after_s":0.4},{"id":"s2l12","visual":"Label 'iron(II) sulphide' (48) over the lump on cue 'iron' + YK.formula 'FeS' (mono 56) under it on 'sulphide'; YK.fpara 'a new substance' (40) on 'جديدة'.","tts_text":"وطلعت مادة جديدة اسمها iron two sulphide، ليها اسم جديد.","screen_text":"iron(II) sulphide, FeS: a new substance","pause_after_s":0.4},{"id":"s2l13","visual":"YK.flashRect around '(II)' in the label on cue 'two' + YK.tag '(II): part of the name' (36, textDim) under it; stage unchanged.","tts_text":"الـ two اللي في الاسم ده جزء من الاسم، وهتفهم معناه بعدين.","screen_text":"(II): part of the name","pause_after_s":0.4},{"id":"s2l14","visual":"Three swatches in a row: 'grey' (iron) and 'yellow' (sulphur) dim with small ✕ marks (YK.wrongMark 40) on cue 'رمادي' / 'أصفر', 'black' (FeS) glows on 'أسود'; the magnet above the lump stays idle on 'بيشدها'; YK.tag 'new properties' on cue 'properties'.","tts_text":"وليها properties جديدة: لونها أسود، مش رمادي ولا أصفر، والـ magnet مش بيشِدّها.","screen_text":"new properties: black, not pulled by the magnet","pause_after_s":0.4},{"id":"s2l15","visual":"In the FeS grid inset, pairs light up one by one (Fe–S, Fe–S…) on cue 'قصاد'; tag '1 iron atom : 1 sulphur atom' (YK.formula 44) on cue 'one'#2.","tts_text":"وفيها one iron atom قصاد كل one sulphur atom، مش أكتر ولا أقل.","screen_text":"1 iron atom : 1 sulphur atom","pause_after_s":0.4},{"id":"s2l16","visual":"YK.termCard(ctx, 96, 380, {term: 'fixed ratio', def: 'the ratio of the parts does not change', align: 'left', p: on cue 'fixed'}); the paired grid pulses once on 'ثابتة'.","tts_text":"ودي اسمها fixed ratio، يعني نسبة ثابتة مبتتغيرش.","screen_text":"fixed ratio: the ratio of the parts does not change","pause_after_s":0.4},{"id":"s2l17","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 340, {term: 'Compound', def: 'A substance formed of two or more elements chemically combined in a fixed ratio.', keys: ['chemically combined', 'fixed ratio'], align: 'left', p: on cue 'compound'}); stage: the FeS lump with its linked grid inset.","tts_text":"المادة دي اسمها compound: elements متّحدة كيميائيًا، وليها fixed ratio كمان.","screen_text":"Compound: A substance formed of two or more elements chemically combined in a fixed ratio.","pause_after_s":0.8},{"id":"s2l18","visual":"Misconception (concept chem.elements-compounds-mixtures.mc1): split stage — left the unlinked grey + yellow mixture inset, right the linked FeS grid, a coral '=' between them on cue 'mixture'. YK.mythLine(ctx, t, {at: YK.cue('s2l18'), wrongAt: YK.cueX('s2l18','غلط'), until: YK.cueEnd('s2l21') + 1.5, text: 'A mixture and a compound are the same thing', x: 96, y: 260, size: 40}) with ✕ (YK.wrongMark) for its whole visible time, no strike-through; the '=' gets YK.wrongMark on the same cue.","tts_text":"فيه ناس فاكرة إن الـ mixture والـ compound حاجة واحدة، وده غلط.","screen_text":"A mixture and a compound are the same thing ✕","pause_after_s":0.4},{"id":"s2l19","visual":"Fix row 1 (held ≥ the myth, the myth line and ✕ stay): left, more yellow powder is poured into the mixture (count grows) on cue 'تتغير'; right, the Fe–S pairs stay 1 : 1 on 'fixed'; YK.list row 'Mixture: the ratio can change · Compound: fixed ratio' + YK.rightMark (mint) under the myth line.","tts_text":"في الـ mixture النسبة ممكن تتغير، إنما الـ compound ليه fixed ratio مبيتغيرش.","screen_text":"Mixture: the ratio can change · Compound: fixed ratio ✓","pause_after_s":0.4},{"id":"s2l20","visual":"Fix row 2: left swatches grey + yellow glow on cue 'فاضل'; right swatch black glows on 'جديدة'; YK.list row 2 + YK.rightMark.","tts_text":"وفي الـ mixture كل جزء فاضل زي ما هو، والـ compound ليه properties جديدة.","screen_text":"Mixture: each part keeps its properties · Compound: new properties ✓","pause_after_s":0.4},{"id":"s2l21","visual":"Fix row 3: the magnet pulls iron out of the left side on cue 'بتفصل'; over the right side it stays idle on 'مش'; YK.list row 3 + YK.rightMark. Lesson DataTable rows (ratio, properties, separation).","tts_text":"والـ physical means بتفصل الـ mixture، إنما الـ compound مش بيتفصل بيها.","screen_text":"Mixture: separated by physical means · Compound: not by physical means ✓","pause_after_s":0.4},{"id":"s2l22","visual":"Three-column board (YK.panel ×3 across the stage): 'element' (one-colour disc grid), 'compound' (linked Fe–S grid), 'mixture' (unlinked grey + yellow) light on cues 'element' / 'compound' / 'mixture'; the myth line has gone.","tts_text":"يعني الـ element نوع atoms واحد، والـ compound متّحد، والـ mixture متخلط.","screen_text":"element: one kind of atom · compound: elements combined · mixture: just mixed","pause_after_s":1},{"id":"s3l2","visual":"Stage: a glass of water YK.beaker(ctx, 1300, 640, 340, 420, {level: 0.65, color: 'rgba(120,160,255,0.30)'}) with a spoon of salt grains above it (YK.dot white) on cue 'بملح'; three YK.chip options 'element' / 'compound' / 'mixture' under the glass on their cues. Worked steps stack in the text panel (YK.list, LTR). Lesson s4 item 'Salt water'.","tts_text":"عندنا مَيّة بملح: ده element ولا compound ولا mixture يا ترى؟","screen_text":"Salt water: element, compound or mixture?","pause_after_s":0.4},{"id":"s3l3","visual":"The salt pours in and the grains vanish into the water (fade, no colour change) on cue 'الملح'; YK.list item 1 builds; the 'element' chip dims to 30% on cue 'element'.","tts_text":"أول خطوة: فيها مادتين، الملح والمية، فأكيد ده مش element أصلًا.","screen_text":"Step 1: 2 substances, salt + water → not an element","pause_after_s":0.4},{"id":"s3l4","visual":"A second spoon of salt pours in on cue 'أكتر'; a small counter of spoons (YK.counter 1 → 2, mono 40) beside the glass; YK.list item 2 (lesson feedback: you can stir in more or less salt).","tts_text":"تاني خطوة: نقدر نحط ملح أكتر أو أقل، فالنسبة بتتغير.","screen_text":"Step 2: more or less salt → the ratio can change","pause_after_s":0.4},{"id":"s3l5","visual":"Zoom inset into the water: salt particles (amber dots) spread between water particles (cyan dots), not linked to them, on cue 'مالح'; YK.list item 3.","tts_text":"تالت خطوة: طعمها مالح، والمية لسه مَيّة، كل جزء فاضل زي ما هو.","screen_text":"Step 3: still salty, still water: each part stays as it is","pause_after_s":0.4},{"id":"s3l6","visual":"The glass sits on a burner (ctx flame); the water level drops 0.65 → 0 (YK.beaker level tween) from cue 'غلّينا' with steam wisps (YK.wave, alpha 0.4); white salt crust stays at the bottom on 'بيفضل'; YK.list item 4 + tag 'physical means' on cue 'physical'.","tts_text":"رابع خطوة: لو غلّينا المية لحد ما تتبخر، الملح بيفضل، وده physical means برضه.","screen_text":"Step 4: boil the water away → the salt is left (physical means)","pause_after_s":0.4},{"id":"s3l7","visual":"The 'mixture' chip glows mint + YK.rightMark on cue 'mixture'; the 'compound' chip dims on 'compound'.","tts_text":"يبقى المية بالملح دي mixture، مش compound خالص.","screen_text":"Salt water: a mixture ✓","pause_after_s":1},{"id":"s3l8","visual":"Self-check on a NEW case (not in the lesson's sort list nor the concept short): stage clears; a salt shaker YK.icon('shaker') with a heap of white grains on cue 'الطعام'; label 'sodium chloride' (44) on cue 'chloride'; YK.tag 'sodium' / 'chlorine' small to the left on their cues.","tts_text":"دورك: ملح الطعام، واسمه sodium chloride، جاي من الـ sodium والـ chlorine مع بعض.","screen_text":"Your turn: table salt (sodium chloride) comes from sodium and chlorine","pause_after_s":0.4},{"id":"s3l9","visual":"Left: a soft grey block (YK.cube, C.steel) cut by a knife YK.icon('knife') on cue 'طري'; a closed jar of pale gas (YK.beaker level 0.95, rgba(200,230,140,0.25)) with a coral warning triangle on 'سام'; the salt heap glows on 'والملح'. Lesson bond s1 hook facts.","tts_text":"الـ sodium طري وبيتفاعل بشدة، والـ chlorine غاز سام، والملح بناكله عادي.","screen_text":"sodium: soft, reacts strongly · chlorine: a poisonous gas","pause_after_s":0.4},{"id":"s3l10","visual":"YK.predictCard(ctx, t, {at: YK.cue('s3l10'), until: YK.cue('s3l11') + 0.4, think: YK.cueEnd('s3l10'), end: YK.cue('s3l11'), kind: 'QUICK CHECK', q: 'Table salt: element, compound or mixture?'}); three YK.chip options on their cues; YK.checkPause(ctx, 1307, 880, {t, start: YK.cueEnd('s3l10'), dur: 4}) think ring + countdown; no answer, no hint during the pause.","tts_text":"ده element ولا compound ولا mixture؟ وقّف الفيديو وفكّر شوية.","screen_text":"Element, compound or mixture?","pause_after_s":4},{"id":"s3l11","visual":"Answer: the 'compound' chip glows mint + YK.rightMark on cue 'compound'; YK.answerSlot(ctx, t, {at: YK.cue('s3l11','compound'), text: 'Compound', x: 420, y: 700}); zoom inset: alternating discs (YK.atomDisc el 'Na' / 'Cl') linked in a grid on 'اتحدوا'.","tts_text":"الإجابة: compound، عشان الـ sodium والـ chlorine اتّحدوا وعملوا مادة جديدة.","screen_text":"Compound ✓","pause_after_s":0.4},{"id":"s3l12","visual":"Reason: the soft block and the gas jar get small ✕ marks (YK.wrongMark 50) on cues 'sodium' / 'chlorine'; the salt heap glows with tag 'new properties' (40, mint) on cue 'properties'.","tts_text":"مش طري زي الـ sodium، ومش سام زي الـ chlorine، فليه properties جديدة.","screen_text":"Not soft and reactive, not a poisonous gas: new properties","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الباب؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, 'Iron: abundance and suitability of iron ore', {kind: 'concept', align: 'left'}) (map title exactly) on cue 'iron'; under it a rough rock (YK.ore(ctx, 1100, 480, 130, {seed: 3})) on cue 'ores'; YK.tag 'iron ores' (40).","tts_text":"في الباب هتقابل الـ iron ores، يعني الخامات اللي بنطلّع منها الـ iron نفسه.","screen_text":"iron ores","pause_after_s":0.4},{"id":"s4l3","visual":"Zoom inset into the rock: linked grey–red disc pairs (YK.atomDisc el 'Fe' / 'O', short links) on cue 'compounds'; YK.tag 'iron compounds (mostly oxides)' (36) on cue 'oxides' (DB wording rule chem-s3-en.ch1.fact.iron-ore-wording).","tts_text":"الخامات دي فيها iron compounds، أغلبها oxides، يعني الـ oxygen متّحد فيها.","screen_text":"iron compounds (mostly oxides)","pause_after_s":0.4},{"id":"s4l4","visual":"Between the linked pairs, unlinked sand-coloured dots (YK.dot, no links) appear on cue 'impurities'; YK.bracket around the whole inset with tag 'mixture' on cue 'mixture' (same pattern as the lesson's rock question).","tts_text":"ومتخلطة بحاجات اسمها impurities، يعني مواد مش عايزينها، فالـ ore كله mixture كده.","screen_text":"mixed with impurities (unwanted substances) → a mixture","pause_after_s":0.4},{"id":"s4l5","visual":"Second YK.chip(ctx, 820, 640, 'Alloys: definition and preparation', {kind: 'concept', align: 'left'}) on cue 'alloys'; two tiny callback icons from s2 (unlinked mixture grid, linked compound grid) beside it on cues 'mixture' / 'compound'. No alloy types or facts (the chapter's lessons).","tts_text":"وفي الـ alloys، يعني السبايك، هتفرّق تاني بين الـ mixture والـ compound كده.","screen_text":"Alloys: definition and preparation","pause_after_s":0.6},{"id":"s4l6","visual":"Recap (s4l6–s4l9 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l6'), until: YK.cue('s4l9'), title: 'Elements, compounds and mixtures', line: 'Element: one kind of atom', pulse: [{word: 'Element', at: YK.cueX('s4l6','element')}]}); stage: the three-column board of s2l22 returns small, 'element' column glowing.","tts_text":"الخلاصة: الـ element فيه نوع واحد من الـ atoms جواه.","screen_text":"Element: one kind of atom","pause_after_s":0.4},{"id":"s4l7","visual":"Same recap card, second line 'Compound: elements combined, fixed ratio, new properties' on cue 'compound'; 'compound' column glows.","tts_text":"والـ compound فيه elements متّحدة، ليها fixed ratio و properties جديدة.","screen_text":"Compound: elements combined, fixed ratio, new properties","pause_after_s":0.4},{"id":"s4l8","visual":"Same recap card, third line 'Mixture: each part keeps its properties' on cue 'mixture'; 'mixture' column glows.","tts_text":"والـ mixture مواد متخلطة، وكل جزء فيه فاضل بنفس الـ properties بتاعته.","screen_text":"Mixture: each part keeps its properties","pause_after_s":0.6},{"id":"s4l9","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Elements, compounds and mixtures', line: 'Compound: combined. Mixture: just mixed.', t, pulse: [{word: 'Compound', at: YK.cueX('s4l9','compound')}, {word: 'Mixture', at: YK.cueX('s4l9','mixture')}]}) held ≥ 2.5 s; no fade to black, no outro.","tts_text":"يعني الـ compound متّحد، والـ mixture متخلط وخلاص.","screen_text":"Compound: combined. Mixture: just mixed.","pause_after_s":1.5}],"logline":"هتعرف تفرّق بين الـ element والـ compound والـ mixture، وتعرف ليه الـ magnet بيشد الـ iron من الـ mixture ومش بيشده من الـ compound.","segments":[{"id":"s1","title":"Koshari, iron and sulphur","concept_id":"chem.elements-compounds-mixtures"},{"id":"s2","title":"Mixture or compound?","concept_id":"chem.elements-compounds-mixtures"},{"id":"s3","title":"Salt water: element, compound or mixture?","concept_id":"chem.elements-compounds-mixtures"},{"id":"s4","title":"Where Chapter 1 uses 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على طبَق كشري رز وعدس ومكرونة متقلبين\nعلى بعض\nوتقدر تطلّع العدس بالمعلقة وكل حاجة فيه\nفاضلة زي ما هي\nوأي مادة حوالينا متكوّنة من atoms يعني\nجسيمات صغيرة جدًا\nالمادة اللي فيها نوع واحد من الـ atoms\nاسمها element كده\nزي برادة الـ iron الرمادي دي كلها atoms من\nنوع واحد\nوالـ sulphur البودرة الصفرا دي element\nتاني بنوع atoms تاني\nوكل مادة ليها properties يعني صفاتها لونها\nوالـ magnet بيشِدّها ولا لأ\nالـ magnet بيشِد الـ iron إنما مش بيشِد\nالـ sulphur خالص\nيبقى معانا تلات كلمات atoms و element و\nproperties خلّيهم في بالك\nنخلط برادة الـ iron مع بودرة الـ sulphur\nونقلّبهم كويس\nتبص تلاقي حبيبات رمادي وحبيبات صفرا كل\nواحدة فاضل ليها نفس الـ properties بتاعتها\nولو قرّبت الـ magnet يشِد الـ iron لوحده\nويسيب الـ sulphur مكانه\nده اسمه mixture مواد متخلطة ببعض وكل مادة\nفاضلة زي ما هي\nوالـ magnet ده physical means يعني بنفصل\nمن غير ما نعمل مادة جديدة\nطب نجيب mixture جديد من الـ iron والـ\nsulphur ونسخّنه جامد\nوبعد التسخين بيطلع جسم صُلب لونه أسود خالص\nتوقّع الـ magnet هيقدر يشِد الـ iron من\nالجسم الأسود ده فكّر\nلأ الـ magnet مش هيشِد حاجة مع إن الـ iron\nلسه جوه\nعشان الـ iron والـ sulphur اتّحدوا\nكيميائيًا والـ atoms بقت ماسكة في بعض\nوطلعت مادة جديدة اسمها iron two sulphide\nليها اسم جديد\nالـ two اللي في الاسم ده جزء من الاسم\nوهتفهم معناه بعدين\nوليها properties جديدة لونها أسود مش رمادي\nولا أصفر والـ magnet مش بيشِدّها\nوفيها one iron atom قصاد كل one sulphur\natom مش أكتر ولا أقل\nودي اسمها fixed ratio يعني نسبة ثابتة\nمبتتغيرش\nالمادة دي اسمها compound elements متّحدة\nكيميائيًا وليها fixed ratio كمان\nفيه ناس فاكرة إن الـ mixture والـ compound\nحاجة واحدة وده غلط\nفي الـ mixture النسبة ممكن تتغير إنما الـ\ncompound ليه fixed ratio مبيتغيرش\nوفي الـ mixture كل جزء فاضل زي ما هو والـ\ncompound ليه properties جديدة\nوالـ physical means بتفصل الـ mixture إنما\nالـ compound مش بيتفصل بيها\nيعني الـ element نوع atoms واحد والـ\ncompound متّحد والـ mixture متخلط\nعندنا مَيّة بملح ده element ولا compound\nولا mixture يا ترى\nأول خطوة فيها مادتين الملح والمية فأكيد ده\nمش element أصلًا\nتاني خطوة نقدر نحط ملح أكتر أو أقل فالنسبة\nبتتغير\nتالت خطوة طعمها مالح والمية لسه مَيّة كل\nجزء فاضل زي ما هو\nرابع خطوة لو غلّينا المية لحد ما تتبخر\nالملح بيفضل وده physical means برضه\nيبقى المية بالملح دي mixture مش compound\nخالص\nدورك ملح الطعام واسمه sodium chloride جاي\nمن الـ sodium والـ chlorine مع بعض\nالـ sodium طري وبيتفاعل بشدة والـ chlorine\nغاز سام والملح بناكله عادي\nده element ولا compound ولا mixture وقّف\nالفيديو وفكّر شوية\nالإجابة compound عشان الـ sodium والـ\nchlorine اتّحدوا وعملوا مادة جديدة\nمش طري زي الـ sodium ومش سام زي الـ\nchlorine فليه properties جديدة\nطب الكلام ده هيفيدك فين في الباب\nفي الباب هتقابل الـ iron ores يعني الخامات\nاللي بنطلّع منها الـ iron نفسه\nالخامات دي فيها iron compounds أغلبها\noxides يعني الـ oxygen متّحد فيها\nومتخلطة بحاجات اسمها impurities يعني مواد\nمش عايزينها فالـ ore كله mixture كده\nوفي الـ alloys يعني السبايك هتفرّق تاني\nبين الـ mixture والـ compound كده\nالخلاصة الـ element فيه نوع واحد من الـ\natoms جواه\nوالـ compound فيه elements متّحدة ليها\nfixed ratio و properties جديدة\nوالـ mixture مواد متخلطة وكل جزء فيه فاضل\nبنفس الـ properties بتاعته\nيعني الـ compound متّحد والـ mixture متخلط\nوخلاص","countable":false,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":66,"see_also":[{"item_id":"chem-s3-en.lesson-fe.occurrence","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Iron: abundance and suitability of iron ore","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":97.35,"kind":"pause_question","spec":{"answer":"لأ: الـ iron والـ sulphur اتحدوا كيميائيًا (iron(II) sulphide, FeS)، مادة جديدة بـ properties جديدة.","prompt":"سخّنا خليط iron و sulphur وطلع جسم أسود: الـ magnet هيقدر يشد الـ iron منه؟","options":[{"id":"a","text":"لأ","correct":true},{"id":"b","text":"أيوه، عشان الـ iron لسه جوه","correct":false}],"answer_t_s":100.89,"concept_id":"chem.elements-compounds-mixtures","misconception_id":"chem.elements-compounds-mixtures.mc1"},"content_lang":"ar-EG"},{"id":"think-2","t_s":236.79,"kind":"pause_question","spec":{"answer":"compound: الـ properties جديدة؛ مش طري وبيتفاعل بشدة زي الـ sodium، ومش غاز سام زي الـ chlorine.","prompt":"table salt (sodium chloride) جاي من sodium و chlorine: element ولا compound ولا mixture؟","options":[{"id":"a","text":"compound","correct":true},{"id":"b","text":"mixture","correct":false},{"id":"c","text":"element","correct":false}],"answer_t_s":241.45,"concept_id":"chem.elements-compounds-mixtures","misconception_id":"chem.elements-compounds-mixtures.mc1"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.elements-compounds-mixtures"]},{"id":"chem-s3-en.video-walkthrough-chem.mixture-separation","kind":"walkthrough","version":5,"ord":345,"content_lang":"ar-EG","primary_concept_id":"chem.mixture-separation","concepts":[{"concept_id":"chem.mixture-separation","role":"primary"}],"title":"Separating mixtures: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.mixture-separation v2 (s1 hook: iron filings in dry sand, same size, sieve vs magnet; s2 KeyTerm 'Magnetic separation' verbatim + 'No new substance forms. The iron is still iron'; s3 KeyTerm 'Surface tension' verbatim + 'hold up some small, light particles. Others sink'; s4 'Some particles take an electric charge more easily… A charged plate attracts them, and the rest fall straight down' + Matching names 'Separation by surface tension', 'Electric separation'; s5 check case = worked example (two fine powders, one stays on the surface); s6 recap 'Next: iron ore is concentrated with these same three methods'). Concept chem.mixture-separation v2 (no recorded misconceptions): s2 refutes the lesson's hook mistake (a sieve works: ✕, same size) and its TrueFalse mistake (filings become a new substance: ✕, iron is still iron), which is also the dependent's fe.ore-dressing.mc2 'Concentration is a chemical change'. Prereqs: chem.elements-compounds-mixtures (mixture keeps its parts' properties), phys.magnetic-field, phys.electric-charges (prereq chips). Dependent named in s4 (in-book): fe.ore-dressing 'Ore dressing: crushing, sintering, concentrating'; book p.17 'c- Concentrating processes: … increase the percentage of iron by removes most of the impurities … The separation of the impurities mixed with the ore done by using the surface tension or magnetic or electric separation'. Crushing/sintering are only in the chip title, not taught. Terms at first use: s1 mixture, property, magnet (3); s2 iron filings, particles, sieve, Magnetic separation, substance, Surface tension, Separation by surface tension, electric charge, charged plate, Electric separation, iron ore, impurities (ore + impurities glossed in s2 so s4 adds no new term). Definition cards s2l9 and s2l15 show the lesson's KeyTerm definitions verbatim (the line speaks the term and its key words). Self-check: NEW case (two same-size powders, a magnet attracts neither, one takes a charge more easily → electric separation); worked example is separation by surface tension. Predicts: s2l4 (~1:05), s3l10 (~4:05). not-in-source: a mother picks dark stones out of rice by their colour; a fridge magnet does not attract rice or paper; fine dust can float on a glass of water; a comb rubbed in dry hair takes an electric charge and attracts small bits of paper; water particles attract each other ('stick together'); iron occurs in nature in rocks called iron ore (book p.16 lists the ores); a sieve separates by size, so same-size grains pass together. Estimated duration ≈ 319 s (≈ 5:19; 627 words at ~2.4 words/s + 43.4 s pauses + joins); planning aid only.","title":"Separating mixtures: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"YK.camera push-in on the plate; on cue 'زلط' each dark stone gets a YK.flashRect ring (C.gold, staggered with YK.stagger 0.08 s). No text (the anchor is a picture).","tts_text":"تخيّل طبَق رز، ووسطه شوية زلط صغير لونه غامق.","screen_text":"","pause_after_s":0.4},{"id":"s1l3","visual":"On cue 'بتنقّي' the stones fly one by one (YK.flyer, arc 0.3, trail) from the plate to a small bowl on the right; the rice dots stay exactly as drawn (same seed) on cue 'نفسه'.","tts_text":"مامتك بتنقّي الزلط بإيدها، من غير ما تغيّر الرز نفسه.","screen_text":"","pause_after_s":0.4},{"id":"s1l4","visual":"Rewind to the full plate (rice + stones); YK.termCard(ctx, 96, 420, {term: 'mixture'}) slides in on cue 'mixture' (text panel x 96–740). New term 1.","tts_text":"الرز والزلط مع بعض كده اسمهم mixture، يعني خليط.","screen_text":"mixture","pause_after_s":0.4},{"id":"s1l5","visual":"The 'mixture' card stays; on the stage two YK.tag pills appear WITHOUT words: a cream dot icon on cue 'رز' and a dark dot icon on cue 'زلط', each with YK.rightMark (size 40) — the parts keep what they are.","tts_text":"في الـ mixture، الحاجات بتفضل زي ما هي: الرز رز، والزلط زلط.","screen_text":"mixture","pause_after_s":0.4},{"id":"s1l6","visual":"Zoom on one stone next to rice grains; a colour swatch pair (dark vs cream circles, ctx) pulses on cue 'لونه'; YK.termCard(ctx, 96, 420, {term: 'property'}) on cue 'property'. New term 2.","tts_text":"مامتك عرفت الزلط من لونه، واللون ده اسمه property، يعني صفة.","screen_text":"property","pause_after_s":0.4},{"id":"s1l7","visual":"The 'property' card stays; stage: a ruler drawn with ctx lines beside a grain on cue 'والحجم', then a small beam YK.balance(ctx, 1300, 760, 360, {value: 0.3}) on cue 'الوزن'. No word labels (Arabic words are not on-screen terms).","tts_text":"والحجم كمان property، وكمان الوزن، وحاجات تانية كتير.","screen_text":"property","pause_after_s":0.4},{"id":"s1l8","visual":"Split stage: stone side lit with the dark swatch + YK.rightMark on cue 'الزلط'; rice side with the same swatch slot empty + YK.wrongMark on cue 'الرز' (✕ held to line end).","tts_text":"السر: استغلت property موجودة في الزلط، ومش موجودة في الرز.","screen_text":"property","pause_after_s":0.4},{"id":"s1l9","visual":"New shot: a fridge door (rounded rect, C.steel) with a horseshoe YK.magnet(ctx, 1300, 520, {kind: 'horseshoe', p: YK.prog(t, YK.cueX('s1l9','magnet'), +0.4)}); YK.termCard {term: 'magnet'} on cue 'magnet'. New term 3. Prereq chip YK.prereqChip(ctx, t, 'Magnets and magnetic fields', {at: YK.cue('s1l9'), until: YK.cueEnd('s1l10'), after: 'From zero'}).","tts_text":"وده الـ magnet، المغناطيس اللي بنلزقه على باب التلاجة.","screen_text":"magnet","pause_after_s":0.4},{"id":"s1l10","visual":"The magnet passes over a few rice grains and a paper scrap (ctx rect, C.text 0.8): nothing moves; YK.wrongMark small beside them on cue 'بيشد' (second one). The magnet's field lines (dashed C.cyan, from YK.magnet) stay on.","tts_text":"الـ magnet بيشِدّ حاجات معينة، ومش بيشِدّ الرز ولا الورق.","screen_text":"magnet","pause_after_s":0.4},{"id":"s1l11","visual":"Three YK.chip(kind 'concept') in the text panel, each popping on its spoken word: 'mixture', 'property', 'magnet' (YK.cueX). Stage shows the three mini pictures (plate, swatch, magnet) side by side.","tts_text":"يبقى معانا تلات كلمات: mixture و property و magnet، خلّيهم في بالك.","screen_text":"mixture · property · magnet","pause_after_s":1},{"id":"s2l2","visual":"Stage: a shallow tray (ctx, C.steel rim); grey metallic grains (YK.dot r 6, C.steel, YK.rng(7)) pour in on cue 'filings'; YK.tag 'iron filings' (44) on cue 'iron' (first). Prereq chip 'Elements, compounds and mixtures' (YK.prereqChip, after 'The idea') at line start, out at s2l3 end.","tts_text":"دي اسمها الـ iron filings، يعني حتت صغيرة أوي من معدن الـ iron كده.","screen_text":"iron filings","pause_after_s":0.4},{"id":"s2l3","visual":"Sand grains (YK.dot r 6, #d6c49a sand colour as the lesson draws it) pour in and mix with the grey grains, SAME radius (one idea: same size); YK.tag 'particles' on cue 'particles' (first); a size ruler (ctx) shows both grains equal.","tts_text":"الحبيبات الصغيرة دي اسمها particles، والرمل كمان particles برضه.","screen_text":"particles","pause_after_s":0.4},{"id":"s2l4","visual":"YK.predictCard(ctx, t, {at: YK.cue('s2l4'), until: YK.cue('s2l5') + 0.4, think: YK.cueEnd('s2l4'), end: YK.cue('s2l5'), kind: 'PREDICT', q: 'Same size: sieve or magnet?'}). Stage: a sieve (ctx circle + mesh lines) on the left on cue 'sieve', YK.magnet on the right on cue 'magnet'. During the pause only the question shows.","tts_text":"تفصلهم إزاي: الـ sieve، يعني المنخل، ولا الـ magnet؟ وقّف وفكّر.","screen_text":"sieve or magnet?","pause_after_s":3},{"id":"s2l5","visual":"The tray is shaken through the sieve: grey AND sand dots fall through together (same size); YK.mythLine(ctx, t, {at: YK.cue('s2l5'), wrongAt: YK.cueX('s2l5','هينفع'), until: YK.cueEnd('s2l6'), text: 'sieve'}) with ✕ held for the whole line and the next one.","tts_text":"الـ sieve مش هينفع، لأن الحبيبات حجمها واحد تقريبًا.","screen_text":"sieve ✕","pause_after_s":0.4},{"id":"s2l6","visual":"YK.magnet sweeps over the tray on cue 'بيشد': grey dots fly up and cling (YK.flyer, short arcs), sand dots stay; YK.rightMark (size 64, bigger than the ✕) on cue 'magnet', held into s2l7.","tts_text":"إنما الـ magnet بيشِدّ الـ iron filings، والرمل يفضل مكانه.","screen_text":"magnet ✓","pause_after_s":0.4},{"id":"s2l7","visual":"Text panel: YK.chip 'mixture' on cue 'mixture' then YK.chip 'property' on cue 'property'; stage: the magnet holding the grey grains, a gold YK.bracket around them on cue 'جزء', the sand heap dimmed to 35% on cue 'التاني'.","tts_text":"يبقى عشان تفصل mixture، دوّر على property في جزء ومش في التاني.","screen_text":"mixture · property","pause_after_s":0.4},{"id":"s2l8","visual":"YK.termCard(ctx, 96, 420, {term: 'Magnetic separation'}) on cue 'magnetic'; stage: the lesson's conveyor picture — a belt (ctx line) carrying mixed dots into a magnetic drum (circle, C.coral 0.25 fill), grey dots follow the drum, sand dots drop straight off; drum starts turning on cue 'فصل'.","tts_text":"الطريقة دي اسمها الـ magnetic separation، يعني فصل بالمغناطيس.","screen_text":"magnetic separation","pause_after_s":0.4},{"id":"s2l9","visual":"YK.termCard gets its def (lesson KeyTerm, verbatim) on cue 'بيشد', keys ['attracts', 'stay behind']; two bins under the drum fill: grey bin on cue 'attract', sand bin on cue 'تفضل'. book_ref: lesson s2 KeyTerm.","tts_text":"في الـ magnetic separation، الـ magnet بيعمل attract، يعني بيشِدّ، والـ particles التانية تفضل.","screen_text":"Magnetic separation: A magnet attracts the particles that are magnetic. The other particles stay behind.","pause_after_s":0.8},{"id":"s2l10","visual":"YK.termCard {term: 'substance'} on cue 'substance'; stage: the two bins with YK.tag 'iron' on the grey bin on cue 'iron'; the sand bin has no word label.","tts_text":"الـ substance يعني مادة، زي الـ iron أو الرمل.","screen_text":"substance","pause_after_s":0.4},{"id":"s2l11","visual":"Myth: the grey bin glows with a coral question pill (YK.pill 'substance?', C.coral) on cue 'جديدة'; YK.wrongMark on cue 'غلط', held for this whole line. Lesson check misconception (no misconception recorded for this concept).","tts_text":"فيه ناس فاكرة إن الـ iron بعد الفصل بقى substance جديدة، وده غلط.","screen_text":"substance? ✕","pause_after_s":0.4},{"id":"s2l12","visual":"Correction, bigger and longer than the myth: zoom into the grey bin — YK.atomDisc grid identical to the one shown before separation (same layout), labels off (el colour only), and a YK.rightMark (size 72) on cue 'لسه' (first), held until s2l13 starts. Myth pill gone.","tts_text":"الـ iron لسه iron، والرمل لسه رمل؛ مفيش substance جديدة اتكونت.","screen_text":"iron → iron ✓","pause_after_s":0.8},{"id":"s2l13","visual":"New shot: YK.beaker(ctx, 1300, 620, 520, 460, {level: 0.6, color: 'rgba(56,189,248,0.25)'}); on cue 'particles' a zoom (YK.zoomThrough to a small grid of water discs, YK.atomDisc el 'H2O' label off, r 30) with short bond lines between neighbours on cue 'لازقة'. YK.scaleBadge in the stage corner.","tts_text":"طريقة تانية: المية نفسها particles صغيرة، لازقة في بعض.","screen_text":"particles","pause_after_s":0.4},{"id":"s2l14","visual":"The top row of water discs highlights (C.cyan glow) on cue 'السطح'; inward arrows between surface discs (ctx) on cue 'الشد'; YK.termCard {term: 'Surface tension'} on cue 'surface'.","tts_text":"الشدّ بين الـ particles دي عند السطح اسمه surface tension، يعني شد السطح.","screen_text":"surface tension","pause_after_s":0.4},{"id":"s2l15","visual":"termCard def (lesson KeyTerm, verbatim) on cue 'شد', keys ['pull', 'thin stretched skin']; zoom back out: the beaker's surface line drawn as a taut cyan membrane (YK.wave amplitude 0) on cue 'جلدة'. book_ref: lesson s3 KeyTerm.","tts_text":"الـ surface tension هو شد الـ particles عند السطح، فيبقى زي جلدة مشدودة.","screen_text":"Surface tension: The pull between water particles at the surface. It makes the surface act like a thin stretched skin.","pause_after_s":0.8},{"id":"s2l16","visual":"Everyday picture: a glass (YK.tube style, wide) with a few fine dust dots resting on the surface line (YK.dot r 4, C.steel) on cue 'عايم'. No text.","tts_text":"عشان كده ممكن تشوف تراب خفيف عايم فوق كوباية مَيّة.","screen_text":"","pause_after_s":0.4},{"id":"s2l17","visual":"Back to the beaker: dark dots (C.steelDark, r 5) sprinkled on cue 'تشيل' rest on the surface; sand dots (#d6c49a) sprinkled on cue 'تغطس' sink and settle at the bottom (YK.tween y, ease.outQuad). Lesson diagram s3.","tts_text":"الجلدة دي تقدر تشيل بعض الـ particles الصغيرة، والتانية تغطس تحت.","screen_text":"particles","pause_after_s":0.4},{"id":"s2l18","visual":"YK.termCard {term: 'Separation by surface tension'} (lesson Matching wording) on cue 'separation'; YK.bracket around the floating dots on cue 'surface', a second bracket around the sunk dots on cue 'السطح'.","tts_text":"ودي كمان separation، إنما عن طريق الـ surface tension، شد السطح.","screen_text":"Separation by surface tension","pause_after_s":0.8},{"id":"s2l19","visual":"New shot: a comb (ctx rounded rect + teeth, C.steel) rubbing back and forth (YK.tween x, 3 strokes) on cue 'تحكه'. No text.","tts_text":"طريقة تالتة: افتكر المشط لما تحُكّه في شَعرك الناشف.","screen_text":"","pause_after_s":0.4},{"id":"s2l20","visual":"Small '−' signs (YK.label, C.cyan 36) appear on the comb on cue 'charge'; YK.termCard {term: 'electric charge'} on cue 'electric'; paper bits (ctx rects) jump up to the comb (YK.flyer) on cue 'فيشد'. Prereq chip 'Electric charges attract and repel' (YK.prereqChip, after 'The idea') from line start to s2l21 end.","tts_text":"المشط بياخد electric charge، شُحنة كهربا، فيشِدّ حتت ورق صغيرة.","screen_text":"electric charge","pause_after_s":0.4},{"id":"s2l21","visual":"Stage: the lesson's electric picture — a funnel (ctx path) at the top, a vertical plate (rect, C.coral 0.35 fill) on the left with '+' marks on cue 'charge'; YK.tag 'charged plate' on cue 'charged'.","tts_text":"وفي الطريقة دي فيه لوح عليه charge، اسمه charged plate كده.","screen_text":"charged plate","pause_after_s":0.4},{"id":"s2l22","visual":"Mixed dots fall from the funnel; the dark dots get a small '−' badge (YK.label 28) on cue 'electric', the sand dots do not; one dark dot pulses (YK.pulse) on cue 'أسهل'.","tts_text":"بعض الـ particles بتاخد electric charge أسهل من غيرها.","screen_text":"electric charge","pause_after_s":0.4},{"id":"s2l23","visual":"Dark dots curve toward the plate and land in the left bin on cue 'يشدها' (YK.flyer arc 0.15); sand dots fall straight into the right bin on cue 'ينزل'. Lesson diagram s4.","tts_text":"الـ charged plate يشِدّها لجنب، والباقي ينزل على طول لتحت.","screen_text":"charged plate","pause_after_s":0.4},{"id":"s2l24","visual":"YK.termCard {term: 'Electric separation'} on cue 'electric'; the two bins get brackets (YK.bracket) on cue 'الفصل'.","tts_text":"ودي اسمها الـ electric separation، يعني الفصل بالكهربا.","screen_text":"electric separation","pause_after_s":0.8},{"id":"s2l25","visual":"New shot: a rock chunk YK.ore(ctx, 1300, 600, 220, {seed: 5}) (industry.js, ore swatch hematite) appears on cue 'صخور'; YK.termCard {term: 'iron ore'} on cue 'ore'. No ore name, no % on screen.","tts_text":"الـ iron في الطبيعة موجود في صخور اسمها iron ore، يعني خام.","screen_text":"iron ore","pause_after_s":0.4},{"id":"s2l26","visual":"Zoom into the rock: ore-coloured grains mixed with light grey grains (YK.dot, seeded); the grey grains get a YK.tag 'impurities' on cue 'impurities'.","tts_text":"والـ iron ore ده متخلط بحاجات مش مطلوبة، اسمها impurities، يعني شوائب.","screen_text":"impurities","pause_after_s":1},{"id":"s3l2","visual":"Stage: two very fine powder heaps (YK.dot r 3, a dark grey C.steelDark and a sand #d6c49a) poured together into one heap on cue 'متخلطين'; YK.chip 'mixture' on cue 'mixture'. The worked example is the lesson's check case (lesson s5).","tts_text":"عندنا نوعين بودرة ناعمة أوي، متخلطين في mixture واحد.","screen_text":"mixture","pause_after_s":0.4},{"id":"s3l3","visual":"Text panel: YK.list step '1' + YK.chip 'property' on cue 'property'; stage: a question ring (YK.thinkRing small) over the heap.","tts_text":"أول خطوة: نسأل، فيه property في نوع ومش في التاني؟","screen_text":"property","pause_after_s":0.4},{"id":"s3l4","visual":"YK.magnet passes over the heap on cue 'نجرب': nothing moves; YK.wrongMark beside the magnet on cue 'هينفع' (held to line end).","tts_text":"نجرب الـ magnet: ولا نوع فيهم بيتشِدّ، يبقى مش هينفع.","screen_text":"magnet ✕","pause_after_s":0.4},{"id":"s3l5","visual":"YK.beaker(ctx, 1300, 640, 600, 300, {level: 0.5}) as a wide dish; powder falls from above on cue 'نرش'. YK.list step '2'.","tts_text":"نرُشّ شوية من الـ mixture على مَيّة في طبَق واسع.","screen_text":"","pause_after_s":0.4},{"id":"s3l6","visual":"Dark dots rest on the cyan surface line on cue 'فوق'; YK.tag 'surface tension' on the surface on cue 'surface'; sand dots sink and settle on cue 'بيغطس'.","tts_text":"نوع بيفضل فوق، شايله الـ surface tension، والتاني بيغطس تحت.","screen_text":"surface tension","pause_after_s":0.4},{"id":"s3l7","visual":"YK.answerSlot(ctx, t, {at: YK.cueX('s3l7','separation'), until: YK.cueEnd('s3l8'), text: 'Separation by surface tension', x: 96, y: 620}); YK.list step '3'.","tts_text":"يبقى الطريقة هي الـ separation عن طريق الـ surface tension، شد السطح.","screen_text":"Separation by surface tension ✓","pause_after_s":0.4},{"id":"s3l8","visual":"A spoon (ctx) skims the floating dots into a small dish on cue 'ونشيل'; both dishes get YK.rightMark on cue 'هم'; YK.tag 'substance' + ✓ (YK.rightMark) on cue 'substance'.","tts_text":"ونشيل اللي فوق؛ النوعين زي ما هم، ومفيش substance جديدة.","screen_text":"substance ✓","pause_after_s":1},{"id":"s3l9","visual":"New case (not the example's): two new heaps, same dot radius, colours violet-grey and C.textDim; a ruler shows equal size on cue 'حجمهم'; YK.magnet passes, nothing moves, small YK.wrongMark on cue 'بيشد'.","tts_text":"دورك: بودرتين حجمهم واحد، والـ magnet مش بيشِدّ أي واحدة فيهم.","screen_text":"magnet ✕","pause_after_s":0.4},{"id":"s3l10","visual":"YK.predictCard(ctx, t, {at: YK.cue('s3l10'), until: YK.cue('s3l11') + 0.4, think: YK.cueEnd('s3l10'), end: YK.cue('s3l11'), kind: 'QUICK CHECK', q: 'Same size. The magnet pulls neither. One takes an electric charge more easily. Which method?'}); during the 4 s silence only the question + think ring show (no answer).","tts_text":"إنما واحدة بتاخد electric charge أسهل، والـ magnet مش بيشِدّ؛ بأنهي طريقة؟ وقّف وفكّر.","screen_text":"electric charge?","pause_after_s":4},{"id":"s3l11","visual":"YK.answerSlot {text: 'Electric separation', at: YK.cueX('s3l11','electric')}; YK.chip 'property' pulses on cue 'property'.","tts_text":"الإجابة: الـ electric separation، لأن الـ charge هو الـ property المختلفة.","screen_text":"Electric separation ✓","pause_after_s":0.4},{"id":"s3l12","visual":"Two small icons in the text panel: sieve (ctx mesh) + YK.wrongMark on cue 'sieve'; magnet + YK.wrongMark on cue 'magnet'. Both ✕ held to line end.","tts_text":"الـ sieve مش هينفع عشان الحجم واحد، والـ magnet مش بيشِدّ.","screen_text":"sieve ✕ · magnet ✕","pause_after_s":0.4},{"id":"s3l13","visual":"Replay of the s2 plate rig with the new heaps: the charged dots curve to the plate on cue 'يشد', the rest fall straight on cue 'تنزل'; two bins, YK.rightMark on each.","tts_text":"الـ charged plate يشِدّ البودرة دي، والتانية تنزل على طول.","screen_text":"charged plate","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الـ chapter؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 96, 300, 'Ore dressing', {kind: 'concept'}) (the dependent's map title) on cue 'Ore'; stage: the iron ore rock from s2l25.","tts_text":"في الـ chapter هتقابل حاجة اسمها الـ Ore dressing، يعني تجهيز الخام.","screen_text":"Ore dressing","pause_after_s":0.4},{"id":"s4l3","visual":"YK.tag 'Concentrating processes' (book p.17 heading) on cue 'Concentrating'; a vertical gauge (ctx bar, C.atomFe) rises on cue 'بترفع' with no number on it.","tts_text":"وجواه خطوة اسمها Concentrating processes، بترفع نسبة الـ iron في الخام.","screen_text":"Concentrating processes","pause_after_s":0.4},{"id":"s4l4","visual":"The light grey impurity grains from s2l26 lift out of the rock and drift off-stage on cue 'بتتشال' (YK.flyer); YK.tag 'impurities' rides with them.","tts_text":"والـ impurities المتخلطة بالخام بتتشال بنفس الطرق دي.","screen_text":"impurities","pause_after_s":0.4},{"id":"s4l5","visual":"Three mini icons from s2 (dish, drum, charged plate) pop in a row with YK.tag labels on cues 'surface', 'magnetic', 'electric' (book p.17: 'surface tension or magnetic or electric separation').","tts_text":"يعني الـ surface tension، والـ magnetic separation، والـ electric separation، اللي اتعلمتها.","screen_text":"surface tension · magnetic separation · electric separation","pause_after_s":0.4},{"id":"s4l6","visual":"The cleaned ore grains stay the same colour and shape; YK.rightMark on cue 'نفس'; YK.tag 'substance' on cue 'substance'.","tts_text":"والـ ore بيفضل نفس المادة، مفيش substance جديدة، زي ما شفنا.","screen_text":"substance ✓","pause_after_s":0.6},{"id":"s4l7","visual":"YK.recapCard(ctx, t, {at: YK.cue('s4l7'), until: Infinity, title: 'Separating mixtures', line: 'Use a property the parts do not share.', pulse: [{word: 'property', at: YK.cueX('s4l7','property')}]}); stage dims to the three method icons.","tts_text":"الخلاصة في الـ separating mixtures: استخدم property مش مشتركة بين الأجزاء.","screen_text":"Separating mixtures","pause_after_s":0.4},{"id":"s4l8","visual":"The three icons pulse in turn on cues 'magnet', 'surface', 'electric'; a mint YK.rightMark under them on cue 'جديدة'. Recap s4l7–s4l9 ≈ 16 s.","tts_text":"الـ magnet، والـ surface tension، والـ electric charge، كلهم بيفصلوا من غير مادة جديدة.","screen_text":"magnet · surface tension · electric charge","pause_after_s":0.4},{"id":"s4l9","visual":"YK.takeaway(ctx, {title: 'Remember', line: 'Use a property the parts do not share. No new substance.', t, pulse: [{word: 'property', at: YK.cueX('s4l9','property')}, {word: 'substance', at: YK.cueX('s4l9','substance')}]}) — the lock-in equals the takeaway card.","tts_text":"يعني: property مش مشتركة بين الأجزاء، ومفيش substance جديدة بتتكوّن.","screen_text":"Use a property the parts do not share. No new substance.","pause_after_s":1.5}],"logline":"هتعرف تختار طريقة فصل أي mixture من الـ property اللي مش مشتركة بين أجزاؤه، من غير ما تتكوّن مادة جديدة.","segments":[{"id":"s1","title":"A plate of rice: picking out the stones","concept_id":"chem.mixture-separation"},{"id":"s2","title":"Three ways to separate a mixture","concept_id":"chem.mixture-separation"},{"id":"s3","title":"Separating two fine powders","concept_id":"chem.mixture-separation"},{"id":"s4","title":"Where Chapter 1 uses 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طبَق رز ووسطه شوية زلط صغير لونه\nغامق\nمامتك بتنقّي الزلط بإيدها من غير ما تغيّر\nالرز نفسه\nالرز والزلط مع بعض كده اسمهم mixture يعني\nخليط\nفي الـ mixture الحاجات بتفضل زي ما هي الرز\nرز والزلط زلط\nمامتك عرفت الزلط من لونه واللون ده اسمه\nproperty يعني صفة\nوالحجم كمان property وكمان الوزن وحاجات\nتانية كتير\nالسر استغلت property موجودة في الزلط ومش\nموجودة في الرز\nوده الـ magnet المغناطيس اللي بنلزقه على\nباب التلاجة\nالـ magnet بيشِد حاجات معينة ومش بيشِد\nالرز ولا الورق\nيبقى معانا تلات كلمات mixture و property و\nmagnet خلّيهم في بالك\nدي اسمها الـ iron filings يعني حتت صغيرة\nأوي من معدن الـ iron كده\nالحبيبات الصغيرة دي اسمها particles والرمل\nكمان particles برضه\nتفصلهم إزاي الـ sieve يعني المنخل ولا الـ\nmagnet وقّف وفكّر\nالـ sieve مش هينفع لأن الحبيبات حجمها واحد\nتقريبًا\nإنما الـ magnet بيشِد الـ iron filings\nوالرمل يفضل مكانه\nيبقى عشان تفصل mixture دوّر على property\nفي جزء ومش في التاني\nالطريقة دي اسمها الـ magnetic separation\nيعني فصل بالمغناطيس\nفي الـ magnetic separation الـ magnet\nبيعمل attract يعني بيشِد والـ particles\nالتانية تفضل\nالـ substance يعني مادة زي الـ iron أو\nالرمل\nفيه ناس فاكرة إن الـ iron بعد الفصل بقى\nsubstance جديدة وده غلط\nالـ iron لسه iron والرمل لسه رمل مفيش\nsubstance جديدة اتكونت\nطريقة تانية المية نفسها particles صغيرة\nلازقة في بعض\nالشد بين الـ particles دي عند السطح اسمه\nsurface tension يعني شد السطح\nالـ surface tension هو شد الـ particles\nعند السطح فيبقى زي جلدة مشدودة\nعشان كده ممكن تشوف تراب خفيف عايم فوق\nكوباية مَيّة\nالجلدة دي تقدر تشيل بعض الـ particles\nالصغيرة والتانية تغطس تحت\nودي كمان separation إنما عن طريق الـ\nsurface tension شد السطح\nطريقة تالتة افتكر المشط لما تحُكّه في\nشَعرك الناشف\nالمشط بياخد electric charge شُحنة كهربا\nفيشِد حتت ورق صغيرة\nوفي الطريقة دي فيه لوح عليه charge اسمه\ncharged plate كده\nبعض الـ particles بتاخد electric charge\nأسهل من غيرها\nالـ charged plate يشِدّها لجنب والباقي\nينزل على طول لتحت\nودي اسمها الـ electric separation يعني\nالفصل بالكهربا\nالـ iron في الطبيعة موجود في صخور اسمها\niron ore يعني خام\nوالـ iron ore ده متخلط بحاجات مش مطلوبة\nاسمها impurities يعني شوائب\nعندنا نوعين بودرة ناعمة أوي متخلطين في\nmixture واحد\nأول خطوة نسأل فيه property في نوع ومش في\nالتاني\nنجرب الـ magnet ولا نوع فيهم بيتشِد يبقى\nمش هينفع\nنرُش شوية من الـ mixture على مَيّة في طبَق\nواسع\nنوع بيفضل فوق شايله الـ surface tension\nوالتاني بيغطس تحت\nيبقى الطريقة هي الـ separation عن طريق الـ\nsurface tension شد السطح\nونشيل اللي فوق النوعين زي ما هم ومفيش\nsubstance جديدة\nدورك بودرتين حجمهم واحد والـ magnet مش\nبيشِد أي واحدة فيهم\nإنما واحدة بتاخد electric charge أسهل والـ\nmagnet مش بيشِد بأنهي طريقة وقّف وفكّر\nالإجابة الـ electric separation لأن الـ\ncharge هو الـ property المختلفة\nالـ sieve مش هينفع عشان الحجم واحد والـ\nmagnet مش بيشِد\nالـ charged plate يشِد البودرة دي والتانية\nتنزل على طول\nطب الكلام ده هيفيدك فين في الـ chapter\nفي الـ chapter هتقابل حاجة اسمها الـ Ore\ndressing يعني تجهيز الخام\nوجواه خطوة اسمها Concentrating processes\nبترفع نسبة الـ iron في الخام\nوالـ impurities المتخلطة بالخام بتتشال\nبنفس الطرق دي\nيعني الـ surface tension والـ magnetic\nseparation والـ electric separation اللي\nاتعلمتها\nوالـ ore بيفضل نفس المادة مفيش substance\nجديدة زي ما شفنا\nالخلاصة في الـ separating mixtures استخدم\nproperty مش مشتركة بين الأجزاء\nالـ magnet والـ surface tension والـ\nelectric charge كلهم بيفصلوا من غير مادة\nجديدة\nيعني property مش مشتركة بين الأجزاء ومفيش\nsubstance جديدة بتتكوّن","countable":false,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":67,"see_also":[{"item_id":"chem-s3-en.lesson-fe.ore-dressing","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Ore dressing: crushing, sintering, concentrating","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":71.18,"kind":"pause_question","spec":{"answer":"الـ magnet: بيشد الـ iron filings والرمل يفضل مكانه؛ الـ sieve مش هينفع لأن الحجم واحد تقريبًا.","prompt":"رمل و iron filings، الحبيبات حجمها واحد تقريبًا: نفصلهم بالـ sieve ولا بالـ magnet؟","options":[{"id":"a","text":"الـ magnet","correct":true},{"id":"b","text":"الـ sieve","correct":false}],"answer_t_s":75.15,"concept_id":"chem.mixture-separation"},"content_lang":"ar-EG"},{"id":"think-2","t_s":250.19,"kind":"pause_question","spec":{"answer":"الـ electric separation: الـ charge هو الـ property المختلفة بين النوعين.","prompt":"بودرتين حجمهم واحد، والـ magnet مش بيشد أي واحدة، بس واحدة بتاخد electric charge أسهل: نفصلهم بأنهي طريقة؟","options":[{"id":"a","text":"electric separation","correct":true},{"id":"b","text":"magnetic separation","correct":false},{"id":"c","text":"الـ sieve","correct":false}],"answer_t_s":254.76,"concept_id":"chem.mixture-separation"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.mixture-separation"]},{"id":"chem-s3-en.video-walkthrough-chem.reaction-types","kind":"walkthrough","version":7,"ord":349,"content_lang":"ar-EG","primary_concept_id":"chem.reaction-types","concepts":[{"concept_id":"chem.reaction-types","role":"primary"}],"title":"Types of chemical reactions: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.reaction-types v1 (s1 hook: heat green copper(II) carbonate → black powder + a gas, wrong options 'it just melted' / 'it took in a gas from the air'; s2 KeyTerm 'Thermal decomposition' verbatim + CuCO3 ->[Δ] CuO + CO2 + 'one compound in, two or more substances out', Δ = heat; s3 KeyTerm 'Simple displacement' verbatim + Zn + CuSO4 -> ZnSO4 + Cu, 'Zinc is above copper in the activity series', blue fades, reddish copper coats the zinc; s4 KeyTerm 'Double displacement' verbatim (AB + CD → AD + CB) + AgNO3 + NaCl -> AgCl↓ + NaNO3 (white solid; AgCl does not dissolve → precipitate ↓) + Reveal NaOH + HCl -> NaCl + H2O (acid + base → salt + water); s5 Classify item Fe + CuSO4 -> FeSO4 + Cu = worked example; s5 MCQ CuSO4 + 2NaOH -> Cu(OH)2↓ + Na2SO4 = self-check (NEW case, a different type from the example); s6 recap + 'Next: roasting… some of its changes are thermal decompositions'). Concept chem.reaction-types v2 (no recorded misconceptions): s2 refutes the lesson's wrong options — 'it just melted' (✕, new substances: colour change + gas), 'it took in a gas from the air' (✕, the gas leaves), and the check's '↓ means a gas leaves' (✕, ↓ = precipitate); s3 repeats the last one. Prereqs: chem.acids-bases-salts, chem.equation-balancing (prereq chips). Dependents named in s4 (in-book, map titles): 'Roasting of iron ore' (book p.17, thermal decomposition), 'Iron(III) oxide Fe₂O₃' (book p.22-23: alkali + iron(III) salt → Fe(OH)3 precipitates; heating Fe(OH)3 / FeSO4), 'Iron(II) oxide FeO' (book p.22: heating iron(II) oxalate); no equations, temperatures or conditions in s4 (left for the chapter). Terms at first use: s1 chemical reaction, element, compound (3; iron, copper, oxygen are examples glossed in Arabic); s2 copper (II) carbonate, (II) (one-line gloss), gas, copper (II) oxide, carbon dioxide, Thermal decomposition, equation, Δ, zinc, solution, copper (II) sulphate, more active, activity series, Simple displacement, Double displacement, silver nitrate, sodium chloride, solid, silver chloride, precipitate, sodium nitrate, acid, hydrochloric acid, base, sodium hydroxide, salt. s3 uses only these plus the compound names built from them (iron (II) sulphate, copper (II) hydroxide). Simple-displacement extra line of the lesson (metals above hydrogen displace it from dilute acids, Mg + 2HCl) is left out to keep length ≤ 6 min. Definition cards s2l10, s2l19, s2l23 show the lesson KeyTerm text verbatim; the line speaks the term and its meaning. Formulas are read by meaning or by the names spoken in neighbouring lines (voicing rule: formulas by name, never letter by letter). Predicts: s2l4 (~1:10), s3l9 (~4:50). not-in-source: a fried egg white cannot turn clear again (new substance) while melted ice is still water; an element is the simplest kind of substance; a compound has properties different from its elements; zinc is grey; tennis doubles swapping partners (anchor); sodium chloride is table salt; sour foods like lemon contain an acid; a base is the opposite of an acid and cancels its sourness (plain meaning); iron is above copper in the activity series (implied by the lesson's Classify answer). Estimated duration ≈ 347 s (≈ 5:47; 686 words at ~2.4 words/s + 45 s pauses + joins); planning aid only.","title":"Types of chemical reactions: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"On cue 'تقلي' the clear blob tweens (YK.mix) to opaque #F4F2FF over 1.2 s; small heat shimmer lines under the pan (ctx, C.molten 0.5). No text.","tts_text":"لما تِقلي بيضة، الجزء الشفاف بيبقى أبيض وناشف.","screen_text":"","pause_after_s":0.4},{"id":"s1l3","visual":"A cool-down: blue frost tint over the pan on cue 'تبرّده', the white stays white; YK.rightMark (size 56) beside the egg on cue 'جديدة'.","tts_text":"ومهما تبرّده، عمره ما هيرجع شفاف تاني؛ دي مادة جديدة.","screen_text":"","pause_after_s":0.4},{"id":"s1l4","visual":"Second picture beside the egg: YK.cube(ctx, 1500, 560, 120, {color: C.cyan}) melting into a puddle (YK.tween height) on cue 'يسيح'; a water drop YK.drop on cue 'مية'; a small ring 'same' drawn as two equal drops (no text).","tts_text":"أما التلج لما يسيح، بيفضل مَيّة؛ مفيش مادة جديدة.","screen_text":"","pause_after_s":0.4},{"id":"s1l5","visual":"The egg picture enlarges (the ice dims to 35%); YK.termCard(ctx, 96, 420, {term: 'chemical reaction'}) on cue 'chemical'. New term 1.","tts_text":"لما مادة جديدة تتكوّن، ده اسمه chemical reaction، يعني تفاعل كيميائي.","screen_text":"chemical reaction","pause_after_s":0.4},{"id":"s1l6","visual":"New shot: two YK.atomDisc (el 'Fe', el 'Cu', r 70, matter.js colours, {symbol: false}) pop on cues 'iron' and 'copper' with YK.tag 'iron' / 'copper'; YK.termCard {term: 'element'} on cue 'element'. New term 2.","tts_text":"أبسط مادة اسمها element، زي الـ iron والـ copper، الحديد والنحاس.","screen_text":"element: iron, copper","pause_after_s":0.4},{"id":"s1l7","visual":"YK.atomDisc el 'O' {symbol: false} joins on cue 'oxygen' with YK.tag 'oxygen'; a few O discs ({symbol: false}) drift as air (YK.particles float, seed 2, alpha 0.35).","tts_text":"والـ oxygen، الغاز اللي بنتنفسه، هو كمان element برضه.","screen_text":"element: oxygen","pause_after_s":0.4},{"id":"s1l8","visual":"Cu and O discs slide together and bond (YK.molecule atoms [{el:'Cu'},{el:'O'}], {symbol: false} on every atom) on cue 'اتحدوا'; YK.termCard {term: 'compound'} on cue 'compound'. New term 3.","tts_text":"لو elements اتّحدوا مع بعض، يعملوا compound، يعني مركّب.","screen_text":"compound","pause_after_s":0.4},{"id":"s1l9","visual":"Split: left the shiny Cu disc + O gas discs (dim; every atomDisc {symbol: false}), right the bonded pair as a black powder heap (YK.dot ×40, C.ink rim) — different look = new properties; gold YK.bracket around the heap on cue 'جديدة'.","tts_text":"والـ compound ليه صفات جديدة، غير صفات الـ elements اللي فيه.","screen_text":"compound","pause_after_s":0.4},{"id":"s1l10","visual":"Three YK.chip(kind 'concept') pop on their spoken words (YK.cueX 'chemical', 'element', 'compound'); stage shows the three mini pictures (egg, Fe disc, Cu–O pair).","tts_text":"يبقى عندنا تلات كلمات: chemical reaction، و element، و compound كمان.","screen_text":"chemical reaction · element · compound","pause_after_s":1},{"id":"s2l2","visual":"YK.tube(ctx, 1300, 560, 120, 420, {angle: -0.3, solid: {color: '#4CAF7A', p: 1}}) with green powder (the lesson's 'green copper(II) carbonate'); YK.tag 'copper (II) carbonate' on cue 'copper'; a burner flame (ctx, C.molten → C.amber) lights on cue 'هنسخّنه'. Prereq chip 'Writing and balancing chemical equations' is NOT shown here (no equation yet).","tts_text":"ده copper two carbonate، مسحوق لونه أخضر، هنسخّنه جامد.","screen_text":"copper (II) carbonate","pause_after_s":0.4},{"id":"s2l3","visual":"YK.tag '(II)' pulses inside the name tag on cue 'two'; nothing else changes (one-line gloss for a zero-basics student).","tts_text":"الـ two ده جزء من الاسم، ومعناه هتعرفه في الفصل.","screen_text":"(II)","pause_after_s":0.4},{"id":"s2l4","visual":"On cue 'أسود' the powder tweens green → black (YK.mix); grey gas puffs leave the tube mouth (YK.particles rise, seed 5) on cue 'gas' with YK.tag 'gas'. YK.predictCard(ctx, t, {at: YK.cueX('s2l4','تفتكر'), until: YK.cue('s2l5') + 0.4, think: YK.cueEnd('s2l4'), end: YK.cue('s2l5'), kind: 'PREDICT', q: 'Green solid heated: black powder + a gas. What happened?'}); during the pause only the question shows.","tts_text":"بقى مسحوق أسود، وطلع منه gas، يعني غاز؛ تفتكر حصل إيه؟ فكّر.","screen_text":"gas","pause_after_s":3},{"id":"s2l5","visual":"Myth as a picture: the melting YK.cube from s1l4 next to the tube, YK.wrongMark (coral, size 64) on cue 'غلط', held for this whole line (no text: 'melted' is not a term).","tts_text":"ناس فاكرة إنه ساح زي التلج، وده غلط.","screen_text":"","pause_after_s":0.4},{"id":"s2l6","visual":"Correction, bigger and longer: black heap + gas puffs, each with a YK.rightMark (size 72) on cues 'اتغير' and 'gas', held into s2l7; the ice picture leaves.","tts_text":"اللون اتغير، وطلع gas؛ يعني اتكونت مواد جديدة، مش نفس المادة.","screen_text":"gas ✓","pause_after_s":0.6},{"id":"s2l7","visual":"Lesson's second wrong option: an arrow OUT of the tube (ctx path, C.mint) + YK.rightMark on cue 'طالع'; an arrow IN from the air (C.coral) + YK.wrongMark on cue 'داخل', ✕ held to line end.","tts_text":"والـ gas ده طالع منه، مش داخل فيه من الهوا.","screen_text":"gas","pause_after_s":0.4},{"id":"s2l8","visual":"YK.tag 'copper (II) oxide' on the black heap on cue 'oxide'; YK.molecule {formula: 'CO2', r: 34} rises from the tube with YK.tag 'carbon dioxide' on cue 'carbon'. The old 'copper (II) carbonate' tag is removed on cue 'الأسود' (the substance changed identity).","tts_text":"المسحوق الأسود copper two oxide، والـ gas اسمه carbon dioxide كده.","screen_text":"copper (II) oxide · carbon dioxide","pause_after_s":0.4},{"id":"s2l9","visual":"YK.termCard(ctx, 96, 420, {term: 'Thermal decomposition'}) on cue 'thermal'; stage: one green block (ctx rounded rect) splits into a black block + a CO2 molecule on cue 'كسّرت'.","tts_text":"ده اسمه thermal decomposition، يعني الحرارة كسّرت الـ compound لحاجات أبسط.","screen_text":"Thermal decomposition","pause_after_s":0.4},{"id":"s2l10","visual":"termCard gets its def (lesson KeyTerm, verbatim) on cue 'بتكسّر', keys ['by heat', 'simpler substances']. book_ref: lesson s2 KeyTerm.","tts_text":"يعني في الـ thermal decomposition، الحرارة بتكسّر compound، ويطلع substances، يعني مواد، أبسط.","screen_text":"Thermal decomposition: Breaking down a compound by heat into simpler substances.","pause_after_s":0.8},{"id":"s2l11","visual":"YK.formula(ctx, 'CuCO_3 ->[Δ] CuO + CO_2', 1300, 520, {size: 64}) (lesson notation, heat sign over the arrow) on cue 'equation'; reactant side glows on cue 'الداخل', product side on cue 'والطالع'. YK.tag 'equation' above it. Prereq chip YK.prereqChip(ctx, t, 'Writing and balancing chemical equations', {at: YK.cue('s2l11'), until: YK.cueEnd('s2l12'), after: 'The idea'}).","tts_text":"ودي الـ equation، يعني المعادلة: الداخل على الشمال، والطالع على اليمين.","screen_text":"equation: CuCO₃ →Δ CuO + CO₂","pause_after_s":0.4},{"id":"s2l12","visual":"YK.flashRect around the Δ over the arrow on cue 'المثلث'; a small flame icon (ctx) appears beside it on cue 'حرارة'.","tts_text":"والمثلث الصغير ده فوق السهم معناه حرارة.","screen_text":"Δ","pause_after_s":0.4},{"id":"s2l13","visual":"Pattern strip in the text panel: one block → two blocks (ctx), the '1' and '2 or more' labels (YK.label mono 48) on cues 'one' and 'two'. The first stage slot fills with a mini 'break down' icon.","tts_text":"القاعدة: one compound داخل، و two أو أكتر طالعين.","screen_text":"1 compound → 2+","pause_after_s":0.8},{"id":"s2l14","visual":"New shot: a grey zinc strip (ctx rect, C.atomZn) on cue 'zinc' with YK.tag 'zinc'; a small YK.atomDisc el 'Zn' {symbol: false} badge on cue 'element'.","tts_text":"تاني نوع: ده الـ zinc، element لونه رمادي.","screen_text":"zinc · element","pause_after_s":0.4},{"id":"s2l15","visual":"YK.beaker(ctx, 1300, 640, 420, 460, {level: 0.65, color: '#3B7BFF'}) blue on cue 'solution' with YK.tag 'solution'; YK.tag 'copper (II) sulphate' on cue 'sulphate'.","tts_text":"وده solution أزرق، فيه copper two sulphate دايب في مَيّة.","screen_text":"solution · copper (II) sulphate","pause_after_s":0.4},{"id":"s2l16","visual":"YK.beaker {color: '#3B7BFF', color2: '#BFD3FF', mix: YK.prog(t, YK.cueX('s2l16','بيبهت'), +2)}; a reddish coat (C.atomCu) grows over the strip on cue 'بتغطي'; YK.tag 'copper' on the coat, 'zinc' tag stays on the strip. Lesson s3 text.","tts_text":"نحط حتة zinc فيه؛ الأزرق بيبهت، وطبَقة copper مايلة للأحمر بتغطيها.","screen_text":"zinc · copper","pause_after_s":0.4},{"id":"s2l17","visual":"Particle view (YK.zoomThrough into the solution, YK.scaleBadge): a Zn disc swaps into the Cu disc's place next to a sulphate group (YK.atomDisc r 46; {symbol: false} on every disc, no 'SO4' label); the Cu disc flies out (YK.flyer) on cue 'مكان'; the Zn disc gets a gold glow and YK.tag 'more active' on cue 'active'.","tts_text":"الـ zinc خد مكان الـ copper، عشان هو الـ more active، يعني أنشَط.","screen_text":"zinc · copper · more active","pause_after_s":0.4},{"id":"s2l18","visual":"A vertical ladder (ctx, 2 rungs only: zinc on the upper rung, copper on the lower) with YK.tag 'activity series' on cue 'activity'; Zn rung lights on cue 'zinc', Cu rung on cue 'copper' (lesson caption 'Zinc is above copper in the activity series'; no other metals drawn).","tts_text":"في ترتيب اسمه activity series، الـ zinc أعلى من الـ copper فيه.","screen_text":"activity series · zinc · copper","pause_after_s":0.4},{"id":"s2l19","visual":"YK.termCard {term: 'Simple displacement', def: lesson KeyTerm verbatim, keys: ['more active', 'takes the place']} on cue 'simple'. book_ref: lesson s3 KeyTerm.","tts_text":"ده اسمه simple displacement: الـ element الـ more active بياخد المكان.","screen_text":"Simple displacement: A more active element takes the place of a less active one in its compound.","pause_after_s":0.4},{"id":"s2l19b","visual":"The termCard from s2l19 with its def stays; keys pulse 'takes the place' on cue 'مكان', the word 'compound' in the def glows on cue 'compound'.","tts_text":"بياخد مكان الـ element الأضعف جوه الـ compound بتاعه.","screen_text":"compound","pause_after_s":0.8},{"id":"s2l20","visual":"YK.formula(ctx, 'Zn + CuSO_4 -> ZnSO_4 + Cu', 1300, 520, {size: 60}); Zn and Cu glow C.gold (elements) on the first 'element' cue and the second; CuSO4 and ZnSO4 glow C.violet (compounds) on the 'compound' cues. The second stage slot fills with a 'swap one' icon.","tts_text":"في الـ equation: element و compound داخلين، و compound و element طالعين.","screen_text":"equation: Zn + CuSO₄ → ZnSO₄ + Cu","pause_after_s":0.8},{"id":"s2l21","visual":"Everyday anchor: a tennis court (ctx lines, C.mint 0.6) with four plain discs (no faces): pairs violet+gold and cyan+pink; on cue 'بدّلوا' gold and pink swap sides (YK.flyer arcs). No text.","tts_text":"تالت نوع: تخيّل ثنائيين بيلعبوا تِنس، وبعدين بدّلوا الشركاء بين بعض.","screen_text":"","pause_after_s":0.4},{"id":"s2l22","visual":"The four discs become YK.atomDisc labelled A, B, C, D (same colours) in two bonded pairs AB and CD; on cue 'بيبدّلوا' B and D swap → AD + CB; YK.formula 'AB + CD -> AD + CB' (lesson notation) builds under them.","tts_text":"في الكيميا، two compounds بيبدّلوا الشركاء بنفس الطريقة دي.","screen_text":"AB + CD → AD + CB","pause_after_s":0.4},{"id":"s2l23","visual":"YK.termCard {term: 'Double displacement', def: lesson KeyTerm verbatim, keys: ['exchange their partners'], formula: false} on cue 'double'. book_ref: lesson s4 KeyTerm.","tts_text":"ده اسمه double displacement، يعني two compounds بيبدّلوا الشركاء.","screen_text":"Double displacement: Two compounds exchange their partners: AB + CD → AD + CB.","pause_after_s":0.8},{"id":"s2l24","visual":"Two clear solutions (YK.beaker ×2, color 'rgba(200,220,255,0.25)') with YK.tag 'silver nitrate' on cue 'silver' and 'sodium chloride' on cue 'sodium'; a salt shaker YK.icon 'shaker' beside the second on cue 'ملح'.","tts_text":"مثال: الـ silver nitrate مع الـ sodium chloride، وده ملح الطعام نفسه.","screen_text":"silver nitrate · sodium chloride","pause_after_s":0.4},{"id":"s2l24b","visual":"YK.predictCard(ctx, t, {at: YK.cue('s2l24b'), until: YK.cue('s2l25') + 0.4, think: YK.cueEnd('s2l24b'), end: YK.cue('s2l25'), kind: 'PREDICT', q: 'Mix them: what will you see?'}) over the two beakers; only the question shows during the pause.","tts_text":"تفتكر لما نخلط الاتنين دول هيحصل إيه؟ وقّف وفكّر.","screen_text":"Mix them: what will you see?","pause_after_s":3},{"id":"s2l25","visual":"One beaker pours into the other on cue 'نخلط'; white specks (YK.dot r 4, #F4F2FF) appear through the liquid on cue 'بيظهر' and drift down; YK.tag 'solid' on cue 'solid'. Lesson caption 'A white solid appears in the solution'.","tts_text":"لما نخلط الـ solutions دول، بيظهر solid أبيض، يعني حاجة جامدة.","screen_text":"solutions · solid","pause_after_s":0.4},{"id":"s2l26","visual":"The white specks settle into a layer at the bottom; YK.tag 'silver chloride: AgCl' on cue 'silver'; specks stay solid (no fading) on cue 'بيدوب'.","tts_text":"الـ solid ده اسمه silver chloride، ومش بيدوب في المية.","screen_text":"silver chloride: AgCl","pause_after_s":0.4},{"id":"s2l27","visual":"YK.termCard {term: 'precipitate'} on cue 'precipitate'; a down arrow drawn as a path (Cairo lacks ↓) beside the white layer on cue 'سهم'.","tts_text":"أي solid بيتكوّن في المحلول ومش بيدوب، اسمه precipitate، وعلامته سهم لتحت.","screen_text":"precipitate ↓","pause_after_s":0.4},{"id":"s2l28","visual":"YK.formula(ctx, 'AgNO_3 + NaCl -> AgCl ↓ + NaNO_3', 1300, 480, {size: 56}) with the ↓ as a drawn path after AgCl; partners Ag/Na highlight and swap on cue 'اتبدلوا' (same colours as the A–D discs); YK.tag 'sodium nitrate' under NaNO3 on cue 'sodium'.","tts_text":"في الـ equation، الشركاء اتبدلوا، وطلع كمان sodium nitrate دايب في المية.","screen_text":"equation: AgNO₃ + NaCl → AgCl ↓ + NaNO₃ · sodium nitrate","pause_after_s":0.4},{"id":"s2l29","visual":"Myth (lesson check's wrong option): YK.mythLine(ctx, t, {at: YK.cue('s2l29'), wrongAt: YK.cueX('s2l29','غلط'), until: YK.cueEnd('s2l29'), text: '↓ = gas', x: 96, y: 620}) with a rising-bubble picture crossed by YK.wrongMark, held for the whole line.","tts_text":"ناس فاكرة إن السهم لتحت معناه gas طالع، وده غلط.","screen_text":"gas ✕","pause_after_s":0.4},{"id":"s2l30","visual":"Correction, bigger and longer: the white layer + the drawn ↓ + YK.rightMark (size 72) on cue 'precipitate', YK.tag 'precipitate' held to s2l31 start.","tts_text":"السهم لتحت معناه precipitate، solid مش بيدوب، قاعد في المحلول.","screen_text":"precipitate ↓ ✓","pause_after_s":0.6},{"id":"s2l31","visual":"A lemon (ctx, C.gold) on cue 'الليمون' with YK.tag 'acid' on cue 'acid'; a lab bottle (YK.icon 'flask') with YK.tag 'hydrochloric acid' on cue 'hydrochloric'. Prereq chip 'Acids, bases and salts' (YK.prereqChip, after 'The idea') from line start to s2l33 end.","tts_text":"الحاجة الحامضة زي الليمون فيها acid؛ وفي المعمل فيه hydrochloric acid مثلًا.","screen_text":"acid · hydrochloric acid","pause_after_s":0.4},{"id":"s2l32","visual":"A second bottle with YK.tag 'base' on cue 'base' and 'sodium hydroxide' on cue 'sodium'; a sourness gauge (YK.momentMeter style semicircle, no numbers) drops to the middle on cue 'وبيلغي'.","tts_text":"والـ base عكس الـ acid، زي الـ sodium hydroxide، وبيلغي حموضته.","screen_text":"base · sodium hydroxide","pause_after_s":0.4},{"id":"s2l33","visual":"YK.formula(ctx, 'NaOH + HCl -> NaCl + H_2O', 1300, 520, {size: 60}) (lesson Reveal); Na and H swap highlight on cue 'بيبدّلوا'; YK.tag 'salt' over NaCl on cue 'salt'; the salt shaker icon from s2l24 returns.","tts_text":"الاتنين بيبدّلوا الشركاء، ويدّوا sodium chloride، نوع من الـ salt، ومَيّة.","screen_text":"NaOH + HCl → NaCl + H₂O · salt","pause_after_s":0.4},{"id":"s2l34","visual":"YK.formula word line 'acid + base -> salt + water' (lesson caption) builds word by word on cues 'acid', 'base', 'salt', 'water'; YK.tag 'double displacement' on cue 'double'. The third stage slot fills with a 'swap two' icon.","tts_text":"يبقى acid مع base يدّوا salt و water؛ ده double displacement برضه.","screen_text":"double displacement: acid + base → salt + water","pause_after_s":0.8},{"id":"s3l2","visual":"YK.formula(ctx, 'Fe + CuSO_4 -> FeSO_4 + Cu', 1300, 460, {size: 64}) (lesson s5 Classify item) on cue 'equation'; Fe glows on cue 'iron', CuSO4 on cue 'copper'. YK.list steps in the text panel (x 96).","tts_text":"عندنا الـ equation دي: الـ iron مع الـ copper two sulphate كده.","screen_text":"equation: Fe + CuSO₄ → FeSO₄ + Cu","pause_after_s":0.4},{"id":"s3l3","visual":"Step 1 (YK.list item 1): Fe boxed gold (YK.bracket) + YK.tag 'element' on cue 'element'; CuSO4 boxed violet + YK.tag 'compound' on cue 'compound'; a small blue beaker icon on cue 'أزرق'.","tts_text":"أول خطوة: الداخل هو element، الـ iron، ومعاه compound أزرق.","screen_text":"element · compound","pause_after_s":0.4},{"id":"s3l4","visual":"Step 2: FeSO4 boxed violet on cue 'compound', Cu boxed gold on cue 'element'; YK.tag 'copper' on Cu.","tts_text":"تاني خطوة: الطالع compound جديد، و element هو الـ copper نفسه.","screen_text":"compound · element · copper","pause_after_s":0.4},{"id":"s3l5","visual":"YK.tag 'iron (II) sulphate' under FeSO4 on cue 'iron'.","tts_text":"والـ compound الجديد ده اسمه iron two sulphate كده.","screen_text":"iron (II) sulphate","pause_after_s":0.4},{"id":"s3l6","visual":"Particle replay (same rig as s2l17): an Fe disc takes the Cu place beside the sulphate disc ({symbol: false} on every disc) on cue 'خد', the Cu disc flies out. Step 3: YK.answerSlot(ctx, t, {at: YK.cueX('s3l6','simple'), until: YK.cueEnd('s3l7'), text: 'Simple displacement', x: 96, y: 640}).","tts_text":"يبقى ده simple displacement، لأن element أنشَط خد مكان element تاني.","screen_text":"Simple displacement ✓","pause_after_s":0.4},{"id":"s3l7","visual":"The two-rung ladder from s2l18 returns with iron on the upper rung and copper below (only these two drawn) on cue 'أعلى'; YK.tag 'activity series'.","tts_text":"ومعناه إن الـ iron أعلى من الـ copper في الـ activity series برضه.","screen_text":"activity series · iron · copper","pause_after_s":1},{"id":"s3l8","visual":"New case (lesson s5 MCQ equation; the worked example was a simple displacement): YK.formula(ctx, 'CuSO_4 + 2NaOH -> Cu(OH)_{2} ↓ + Na_2SO_4', 1300, 460, {size: 56}) with the ↓ drawn as a path after Cu(OH)2 (kit formula trap: Cu(OH)_{2}).","tts_text":"دورك: الـ copper two sulphate مع الـ sodium hydroxide، شوف الـ equation كويس.","screen_text":"CuSO₄ + 2NaOH → Cu(OH)₂ ↓ + Na₂SO₄","pause_after_s":0.4},{"id":"s3l9","visual":"YK.predictCard(ctx, t, {at: YK.cue('s3l9'), until: YK.cue('s3l10') + 0.4, think: YK.cueEnd('s3l9'), end: YK.cue('s3l10'), kind: 'QUICK CHECK', q: 'Which type is it? What does ↓ after Cu(OH)2 tell you?'}) (↓ drawn as a path); during the 4 s silence only the question and the think ring show.","tts_text":"أنهي نوع ده؟ والسهم لتحت ده معناه إيه؟ وقّف وفكّر.","screen_text":"↓ ?","pause_after_s":4},{"id":"s3l10","visual":"YK.answerSlot {text: 'Double displacement', at: YK.cueX('s3l10','double')}; Cu and Na highlight and swap partners in the formula on cue 'بدّلوا'.","tts_text":"الإجابة: double displacement، لأن two compounds بدّلوا الشركاء.","screen_text":"Double displacement ✓","pause_after_s":0.4},{"id":"s3l11","visual":"A beaker with a settling solid layer (YK.dot, neutral C.steel, no colour claim) on cue 'precipitate'; YK.tag 'copper (II) hydroxide' + 'precipitate' on cue 'hydroxide'.","tts_text":"والسهم معناه إن الـ copper two hydroxide ده precipitate، مش gas طالع.","screen_text":"copper (II) hydroxide ↓ precipitate · gas ✕","pause_after_s":0.4},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الـ chapter بتاعنا؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 96, 300, 'Roasting of iron ore', {kind: 'concept'}) (map title) on cue 'Roasting'; stage: YK.ore(ctx, 1300, 600, 200, {seed: 2}) in a kiln glow (YK.kiln, industry.js) on cue 'تسخينه'.","tts_text":"في الـ chapter هتقابل الـ Roasting بتاع الـ iron ore، يعني تسخينه جامد.","screen_text":"Roasting of iron ore","pause_after_s":0.4},{"id":"s4l3","visual":"The 'break down' icon from s2 slides onto the kiln on cue 'بيتكسر'; YK.tag 'thermal decomposition' on cue 'thermal' (book p.17 roasting; no equation shown, the chapter teaches it).","tts_text":"وهناك compound بيتكسر بالحرارة لمواد أبسط: ده thermal decomposition اللي عرفناه.","screen_text":"thermal decomposition","pause_after_s":0.4},{"id":"s4l4","visual":"YK.chip 'Iron(III) oxide Fe₂O₃' (map title) on cue 'iron'; a red-brown powder heap (C.hematite, the book's colour for Fe2O3 ore) on the stage.","tts_text":"وهتقابل الـ iron three oxide، وطريقة تحضيره فيها الأنواع دي.","screen_text":"Iron(III) oxide Fe₂O₃","pause_after_s":0.4},{"id":"s4l5","visual":"Two icons only: the drawn ↓ + solid layer on cue 'precipitate', then the 'break down' icon on cue 'thermal'; no formulas, no temperatures (conditions stay for the chapter).","tts_text":"فيه precipitate بيتكوّن، وبعدين thermal decomposition؛ والتفاصيل هتعرفها في الفصل.","screen_text":"precipitate · thermal decomposition","pause_after_s":0.4},{"id":"s4l6","visual":"YK.chip 'Iron(II) oxide FeO' (map title) on cue 'iron'; a black powder heap (book: FeO black powder) + the flame icon on cue 'التسخين'.","tts_text":"والـ iron two oxide من طرق تحضيره التسخين، وده هتشوفه في الفصل.","screen_text":"Iron(II) oxide FeO","pause_after_s":0.6},{"id":"s4l7","visual":"YK.recapCard(ctx, t, {at: YK.cue('s4l7'), until: Infinity, title: 'Recap', line: 'Break down, swap one, swap two', pulse: [{word: 'Break', at: YK.cueX('s4l7','thermal')}, {word: 'one', at: YK.cueX('s4l7','simple')}]}). Recap s4l7–s4l9 ≈ 16 s.","tts_text":"الخلاصة: thermal decomposition بيكسّر compound، والـ simple displacement بيبدّل one element بس.","screen_text":"Recap","pause_after_s":0.4},{"id":"s4l8","visual":"recapCard pulse on 'two' at cue 'double'; the drawn ↓ icon blinks on cue 'precipitate'.","tts_text":"والـ double displacement، two compounds بيبدّلوا الشركاء، وممكن يطلع precipitate كمان.","screen_text":"Double displacement · precipitate","pause_after_s":0.4},{"id":"s4l9","visual":"YK.takeaway(ctx, {title: 'Remember', line: 'Thermal decomposition · simple displacement · double displacement', t, pulse: [{word: 'Thermal', at: YK.cueX('s4l9','thermal')}, {word: 'simple', at: YK.cueX('s4l9','simple')}, {word: 'double', at: YK.cueX('s4l9','double')}]}) — the lock-in equals the takeaway card.","tts_text":"يعني: thermal decomposition، و simple displacement، و double displacement، تلات أنواع هنقابلها.","screen_text":"Thermal decomposition · simple displacement · double displacement","pause_after_s":1.5}],"logline":"هتعرف تفرّق من الـ equation بين الـ thermal decomposition والـ simple displacement والـ double displacement، وتفهم السهم لتحت يعني precipitate.","segments":[{"id":"s1","title":"A fried egg and melting ice","concept_id":"chem.reaction-types"},{"id":"s2","title":"Three types of chemical reaction","concept_id":"chem.reaction-types"},{"id":"s3","title":"Which type is this reaction?","concept_id":"chem.reaction-types"},{"id":"s4","title":"Where Chapter 1 uses reaction 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تِقلي بيضة الجزء الشفاف بيبقى أبيض\nوناشف\nومهما تبرّده عمره ما هيرجع شفاف تاني دي\nمادة جديدة\nأما التلج لما يسيح بيفضل مَيّة مفيش مادة\nجديدة\nلما مادة جديدة تتكوّن ده اسمه chemical\nreaction يعني تفاعل كيميائي\nأبسط مادة اسمها element زي الـ iron والـ\ncopper الحديد والنحاس\nوالـ oxygen الغاز اللي بنتنفسه هو كمان\nelement برضه\nلو elements اتّحدوا مع بعض يعملوا compound\nيعني مركّب\nوالـ compound ليه صفات جديدة غير صفات الـ\nelements اللي فيه\nيبقى عندنا تلات كلمات chemical reaction و\nelement و compound كمان\nده copper two carbonate مسحوق لونه أخضر\nهنسخّنه جامد\nالـ two ده جزء من الاسم ومعناه هتعرفه في\nالفصل\nبقى مسحوق أسود وطلع منه gas يعني غاز تفتكر\nحصل إيه فكّر\nناس فاكرة إنه ساح زي التلج وده غلط\nاللون اتغير وطلع gas يعني اتكونت مواد\nجديدة مش نفس المادة\nوالـ gas ده طالع منه مش داخل فيه من الهوا\nالمسحوق الأسود copper two oxide والـ gas\nاسمه carbon dioxide كده\nده اسمه thermal decomposition يعني الحرارة\nكسّرت الـ compound لحاجات أبسط\nيعني في الـ thermal decomposition الحرارة\nبتكسّر compound ويطلع substances يعني مواد\nأبسط\nودي الـ equation يعني المعادلة الداخل على\nالشمال والطالع على اليمين\nوالمثلث الصغير ده فوق السهم معناه حرارة\nالقاعدة one compound داخل و two أو أكتر\nطالعين\nتاني نوع ده الـ zinc element لونه رمادي\nوده solution أزرق فيه copper two sulphate\nدايب في مَيّة\nنحط حتة zinc فيه الأزرق بيبهت وطبَقة\ncopper مايلة للأحمر بتغطيها\nالـ zinc خد مكان الـ copper عشان هو الـ\nmore active يعني أنشَط\nفي ترتيب اسمه activity series الـ zinc\nأعلى من الـ copper فيه\nده اسمه simple displacement الـ element\nالـ more active بياخد المكان\nبياخد مكان الـ element الأضعف جوه الـ\ncompound بتاعه\nفي الـ equation element و compound داخلين\nو compound و element طالعين\nتالت نوع تخيّل ثنائيين بيلعبوا تِنس وبعدين\nبدّلوا الشركاء بين بعض\nفي الكيميا two compounds بيبدّلوا الشركاء\nبنفس الطريقة دي\nده اسمه double displacement يعني two\ncompounds بيبدّلوا الشركاء\nمثال الـ silver nitrate مع الـ sodium\nchloride وده ملح الطعام نفسه\nتفتكر لما نخلط الاتنين دول هيحصل إيه وقّف\nوفكّر\nلما نخلط الـ solutions دول بيظهر solid\nأبيض يعني حاجة جامدة\nالـ solid ده اسمه silver chloride ومش\nبيدوب في المية\nأي solid بيتكوّن في المحلول ومش بيدوب اسمه\nprecipitate وعلامته سهم لتحت\nفي الـ equation الشركاء اتبدلوا وطلع كمان\nsodium nitrate دايب في المية\nناس فاكرة إن السهم لتحت معناه gas طالع وده\nغلط\nالسهم لتحت معناه precipitate solid مش\nبيدوب قاعد في المحلول\nالحاجة الحامضة زي الليمون فيها acid وفي\nالمعمل فيه hydrochloric acid مثلًا\nوالـ base عكس الـ acid زي الـ sodium\nhydroxide وبيلغي حموضته\nالاتنين بيبدّلوا الشركاء ويدّوا sodium\nchloride نوع من الـ salt ومَيّة\nيبقى acid مع base يدّوا salt و water ده\ndouble displacement برضه\nعندنا الـ equation دي الـ iron مع الـ\ncopper two sulphate كده\nأول خطوة الداخل هو element الـ iron ومعاه\ncompound أزرق\nتاني خطوة الطالع compound جديد و element\nهو الـ copper نفسه\nوالـ compound الجديد ده اسمه iron two\nsulphate كده\nيبقى ده simple displacement لأن element\nأنشَط خد مكان element تاني\nومعناه إن الـ iron أعلى من الـ copper في\nالـ activity series برضه\nدورك الـ copper two sulphate مع الـ sodium\nhydroxide شوف الـ equation كويس\nأنهي نوع ده والسهم لتحت ده معناه إيه وقّف\nوفكّر\nالإجابة double displacement لأن two\ncompounds بدّلوا الشركاء\nوالسهم معناه إن الـ copper two hydroxide\nده precipitate مش gas طالع\nطب الكلام ده هيفيدك فين في الـ chapter\nبتاعنا\nفي الـ chapter هتقابل الـ Roasting بتاع\nالـ iron ore يعني تسخينه جامد\nوهناك compound بيتكسر بالحرارة لمواد أبسط\nده thermal decomposition اللي عرفناه\nوهتقابل الـ iron three oxide وطريقة تحضيره\nفيها الأنواع دي\nفيه precipitate بيتكوّن وبعدين thermal\ndecomposition والتفاصيل هتعرفها في الفصل\nوالـ iron two oxide من طرق تحضيره التسخين\nوده هتشوفه في الفصل\nالخلاصة thermal decomposition بيكسّر\ncompound والـ simple displacement بيبدّل\none element بس\nوالـ double displacement two compounds\nبيبدّلوا الشركاء وممكن يطلع precipitate\nكمان\nيعني thermal decomposition و simple\ndisplacement و double displacement تلات\nأنواع هنقابلها","countable":false,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":68,"see_also":[{"item_id":"chem-s3-en.lesson-fe.roasting","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Roasting of iron ore","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":66.71,"kind":"pause_question","spec":{"answer":"اتكوّنت مواد جديدة: اللون اتغير وطلع gas، فمبقاش نفس المادة.","prompt":"سخّنا copper (II) carbonate: بقى مسحوق أسود وطلع منه gas. حصل إيه؟","options":[{"id":"a","text":"اتكوّنت مواد جديدة","correct":true},{"id":"b","text":"ساح زي التلج، ولسه نفس المادة","correct":false}],"answer_t_s":70.26,"concept_id":"chem.reaction-types"},"content_lang":"ar-EG"},{"id":"think-2","t_s":196.06,"kind":"pause_question","spec":{"answer":"بيظهر solid أبيض: ده silver chloride (AgCl).","prompt":"silver nitrate + sodium chloride (الاتنين solutions): لما نخلطهم هيحصل إيه؟","options":[{"id":"a","text":"بيظهر solid أبيض","correct":true},{"id":"b","text":"بيطلع gas","correct":false},{"id":"c","text":"مفيش حاجة تتغير","correct":false}],"answer_t_s":199.29,"concept_id":"chem.reaction-types"},"content_lang":"ar-EG"},{"id":"think-3","t_s":302.56,"kind":"pause_question","spec":{"answer":"double displacement: اتنين compounds بدّلوا الشركاء؛ والـ ↓ معناه إن الـ copper (II) hydroxide precipitate.","prompt":"CuSO₄ + 2NaOH → Cu(OH)₂ ↓ + Na₂SO₄: أنهي نوع reaction؟ والسهم لتحت معناه إيه؟","options":[{"id":"a","text":"double displacement · ↓ = precipitate","correct":true},{"id":"b","text":"simple displacement · ↓ = gas","correct":false},{"id":"c","text":"thermal decomposition · ↓ = precipitate","correct":false}],"answer_t_s":307.09,"concept_id":"chem.reaction-types"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.reaction-types"]},{"id":"chem-s3-en.video-walkthrough-stoich.molar-mass","kind":"walkthrough","version":5,"ord":351,"content_lang":"ar-EG","primary_concept_id":"stoich.molar-mass","concepts":[{"concept_id":"stoich.molar-mass","role":"primary"}],"title":"Molar mass: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-stoich.molar-mass v1 (s1 hook: 'A mole is a fixed count of particles (6.02 × 10^23)', predict Fe = 56, O = 16, mass of one mole of Fe2O3, wrong options 72 g (56 + 16) and 5 g (counting atoms); s2 KeyTerm 'Molar mass' verbatim (book Ch.2 'Feed Back' p.30), rounded atomic masses table Fe 56, O 16, C 12, H 1, 'Multiply each atomic mass by the number of its atoms. Then add.', callout 'A subscript multiplies the atom, or the bracketed group, just before it. In CO3 the 3 counts O only; in Fe2(SO4)3 it counts the whole SO4 group'; s3 worked example Fe2O3 = 2 × 56 + 3 × 16 = 112 + 48 = 160 g/mol + Reveal 2Fe2O3·3H2O = 2 × 160 + 3 × 18 = 374 g/mol ('the dot means add the water's mass'; 'Each H2O is 2 × 1 + 16 = 18'; 'the numbers in front multiply the whole unit'); s5 FillBlank FeCO3 = 116 g/mol = self-check (NEW case; mistakes 84/72/348/5 explained by the subscript rule); s6 'You will use molar mass to find the percentage of iron in an ore'). All arithmetic recomputed by script (160, 374, 116, 18). Concept stoich.molar-mass v2 (no recorded misconceptions): s2 refutes the hook's wrong options 56 + 16 = 72 (✕, two Fe and three O) and 2 + 3 = 5 (✕, add masses, not atom counts), and the name numeral '(III)' read as an atom count (✕); s3 self-check answer repeats 'the 3 counts O only'. Prereqs: atom.atomic-mass-number, chem.valency-formulas (prereq chips). Dependent named in s4: stoich.mass-percentage 'Mass percentage of an element' (uses molar mass for iron % in an ore) and its in-book dependent fe.roasting 'Roasting of iron ore' (book p.17 compares iron % before/after; no values given in s4). Terms at first use: s1 atom, atomic mass, mole (3; iron, oxygen are glossed examples; Fe/O symbols shown as 'iron: Fe'); s2 compound, formula, hydrogen, subscript, carbonate, carbon, iron (III) oxide + (III) gloss, Molar mass, g/mol, the hydrate dot. s3 adds no term (iron (II) carbonate is built from carbonate + the (II)/(III) naming gloss; the ore names limonite/siderite are not used). Symbols and units on screen (Fe, O, C, H, g/mol) are voiced by name (iron, oxygen…) and as «جرام لكل mole» per the voicing rule (formulas by name, never letter by letter). Definition card s2l19 shows the lesson KeyTerm verbatim. Spoken numbers appear on screen in the same line. Predicts: s2l14 (~2:05), s3l12 (~4:20). not-in-source: eggs are sold by the dozen, a dozen is 12 whatever the egg size (anchor); an iron atom is much heavier than an oxygen atom (56 vs 16); one mole of iron atoms has a mass of 56 g (rounded atomic mass in grams); atoms of different elements combine into a compound such as water; some compounds hold water written after a dot. Estimated duration ≈ 315 s (≈ 5:15; 614 words at ~2.4 words/s + 44.4 s pauses + joins); planning aid only.","title":"Molar mass: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"YK.camera push-in on the carton; the eggs pop in one by one (YK.stagger 0.05 s) on cue 'بالدستة'. No text.","tts_text":"لما بتشتري بيض، بتشتريه بالدستة، صح؟","screen_text":"","pause_after_s":0.4},{"id":"s1l3","visual":"YK.counter(t, YK.cueX('s1l3','twelve'), 0.8, 0, 12) drawn with YK.label mono 96 above the carton; on cue 'حجم' a second carton of larger eggs appears beside it, its counter also 12.","tts_text":"الدستة twelve بيضة، مهما كان حجم البيض.","screen_text":"12","pause_after_s":0.4},{"id":"s1l4","visual":"The two cartons on a YK.balance(ctx, 1300, 820, 520, {value: 0.4}) — the big-egg side goes down on cue 'كتلة' (same count, different mass). No text.","tts_text":"يعني الدستة عدد ثابت، مش كتلة ثابتة.","screen_text":"","pause_after_s":0.4},{"id":"s1l5","visual":"New shot: an iron nail (ctx, C.steel) zooms (YK.zoomThrough, YK.scaleBadge '×10^8') into a grid of YK.atomDisc el 'Fe' (r 40) on cue 'حبيبات'; YK.tag 'iron' on the nail on cue 'iron'; YK.termCard(ctx, 96, 420, {term: 'atom'}) on cue 'atom'. New term 1. Prereq chip YK.prereqChip(ctx, t, 'Atomic number and mass number', {at: YK.cue('s1l5'), until: YK.cueEnd('s1l9'), after: 'From zero'}).","tts_text":"الـ iron، الحديد، معمول من حبيبات صغيرة جدًا، اسمها atom، يعني ذرة.","screen_text":"atom · iron","pause_after_s":0.4},{"id":"s1l6","visual":"YK.atomDisc el 'O' (r 30) float in from the top (YK.particles float, seed 3) on cue 'oxygen' with YK.tag 'oxygen'.","tts_text":"والـ oxygen، الغاز اللي بنتنفسه، معمول من atoms برضه.","screen_text":"oxygen","pause_after_s":0.4},{"id":"s1l7","visual":"Two YK.tag pills in the text panel: 'iron: Fe' on cue 'iron', 'oxygen: O' on cue 'oxygen'; the discs show their symbols (YK.atomDisc symbol:true) on the same cues.","tts_text":"الـ iron ليه رمز، والـ oxygen ليه رمز، زي اللي قدامك كده.","screen_text":"iron: Fe · oxygen: O","pause_after_s":0.4},{"id":"s1l8","visual":"YK.termCard {term: 'atomic mass'} on cue 'atomic'; YK.label 'Fe = 56' (mono 56) on cue 'fifty-six', 'O = 16' on cue 'sixteen' (each number appears on its spoken word). New term 2.","tts_text":"الـ atom ليه كتلة اسمها atomic mass: الـ iron fifty-six، والـ oxygen sixteen كمان.","screen_text":"atomic mass: Fe = 56 · O = 16","pause_after_s":0.4},{"id":"s1l9","visual":"One Fe disc and one O disc on the two pans of YK.balance(ctx, 1300, 760, 520, {left: 'Fe', right: 'O', value: -0.6}); the Fe side drops on cue 'أتقل'.","tts_text":"يعني الـ atom بتاع الـ iron أتقَل من بتاع الـ oxygen بكتير.","screen_text":"Fe = 56 · O = 16","pause_after_s":0.4},{"id":"s1l10","visual":"Split: the egg carton (left, dimmed) and a big box of Fe discs (right); YK.termCard {term: 'mole'} on cue 'mole'; on cue 'ضخم' the box's disc grid zooms out into a dense texture (YK.dot ×600, seed 9). New term 3.","tts_text":"والـ mole زي الدستة، عدد ثابت من الـ atoms، إنما ضخم جدًا.","screen_text":"mole","pause_after_s":0.4},{"id":"s1l11","visual":"YK.formula(ctx, '6.02 × 10^23', 1300, 520, {size: 72}) builds left to right on the spoken parts (YK.cueX 'six', 'ten', 'twenty-three'); lesson hook note 'A mole is a fixed count of particles (6.02 × 10^23)'.","tts_text":"الـ mole فيه six point zero two times ten to the power twenty-three بالظبط.","screen_text":"mole = 6.02 × 10²³","pause_after_s":0.6},{"id":"s1l12","visual":"A scale pan (YK.balance, single pan style) with a heap of Fe discs; YK.label '56 g' (mono 64) on cue 'fifty-six'; the '1 mole' tag on the heap on cue 'one'.","tts_text":"يعني one mole من atoms الـ iron، كتلته fifty-six grams بالظبط.","screen_text":"1 mole of iron: 56 g","pause_after_s":0.4},{"id":"s1l13","visual":"Three YK.chip(kind 'concept') pop on their spoken words (YK.cueX 'atom', 'atomic', 'mole'); stage shows the three mini pictures (Fe disc, balance, egg-carton box).","tts_text":"يبقى معانا: atom، و atomic mass، و mole، خلّيهم في بالك.","screen_text":"atom · atomic mass · mole","pause_after_s":1},{"id":"s2l2","visual":"YK.molecule(ctx, 1300, 560, {formula: 'H2O', r: 60, p: YK.prog(t, YK.cueX('s2l2','تتحد'), +0.6)}) assembles from loose discs; YK.termCard {term: 'compound'} on cue 'compound'; a water glass icon on cue 'المية'.","tts_text":"لما atoms مختلفة تتّحد مع بعض، بتعمل compound، زي المَيّة.","screen_text":"compound","pause_after_s":0.4},{"id":"s2l3","visual":"YK.formula 'H_2O' (mono 96) appears under the molecule on cue 'formula' with YK.tag 'formula'. Prereq chip 'Valency and writing chemical formulas' (YK.prereqChip, after 'The idea') from line start to s2l9 end.","tts_text":"والـ formula بتاعته بتقولك فيه كام atom من كل نوع.","screen_text":"formula","pause_after_s":0.4},{"id":"s2l4","visual":"The subscript 2 in H_2O glows gold on cue 'الصغير'; the two H discs of the molecule pulse on cue 'two' (second); YK.tag 'hydrogen × 2' on cue 'hydrogen'.","tts_text":"في المية، الرقم الصغير two جنب الـ hydrogen، يعني two atoms منه.","screen_text":"H₂O: hydrogen × 2","pause_after_s":0.4},{"id":"s2l5","visual":"The O of H_2O glows; the single O disc pulses; YK.tag 'oxygen × 1' on cue 'one'.","tts_text":"والـ oxygen مالوش رقم، يعني one atom لوحده.","screen_text":"oxygen × 1","pause_after_s":0.4},{"id":"s2l6","visual":"YK.termCard {term: 'subscript'} on cue 'subscript'; a small gold arrow (ctx path) from the 2 back to the H on cue 'قبله'.","tts_text":"الرقم الصغير ده اسمه subscript، وبيعِدّ الـ atom اللي قبله على طول.","screen_text":"subscript","pause_after_s":0.4},{"id":"s2l7","visual":"YK.formula 'Fe_2(SO_4)_3' (lesson callout) on cue 'قوس'; a YK.bracket around (SO4) and a gold arrow from the outer 3 to the whole bracket on cue 'جوا'. No numbers spoken, so no numbers are highlighted.","tts_text":"ولو قبله قوس، زي الـ iron three sulphate، بيعِدّ كل اللي جوا القوس.","screen_text":"( )","pause_after_s":0.4},{"id":"s2l8","visual":"YK.formula 'CO_3' (mono 96) on cue 'carbonate' + YK.tag 'carbonate'; one C disc (YK.atomDisc el 'C') on cue 'one', three O discs on cue 'three'; tags 'carbon × 1', 'oxygen × 3'.","tts_text":"زي مجموعة اسمها carbonate، فيها one carbon و three oxygen معاه.","screen_text":"carbonate CO₃: carbon × 1, oxygen × 3","pause_after_s":0.4},{"id":"s2l9","visual":"Gold arrow from the 3 to the O (YK.rightMark on cue 'oxygen'); a coral dashed arrow to the C with YK.wrongMark on cue 'carbon', ✕ held to line end. Lesson callout 'In CO3 the 3 counts O only'.","tts_text":"الـ three دي بتعِدّ الـ oxygen، مش الـ carbon؛ عشان قبلها على طول.","screen_text":"3 → oxygen ✓ · carbon ✕","pause_after_s":0.4},{"id":"s2l10","visual":"Lesson DataTable as a 4-column table (ctx grid, YK.label): headers '| Fe | O | C | H' (first header cell empty), row label 'Atomic mass'; the Fe cell '56' on cue 'fifty-six', the O cell '16' on cue 'sixteen'.","tts_text":"ودي الـ atomic masses اللي هنستخدمها: iron fifty-six، و oxygen sixteen كمان.","screen_text":"atomic mass: Fe = 56 · O = 16","pause_after_s":0.4},{"id":"s2l11","visual":"C cell '12' on cue 'twelve', H cell '1' on cue 'one'; caption YK.tag 'Rounded atomic masses' (lesson caption) on cue 'مقرّبة'.","tts_text":"والـ carbon twelve، والـ hydrogen one؛ دي atomic masses مقرّبة.","screen_text":"C = 12 · H = 1","pause_after_s":0.4},{"id":"s2l12","visual":"YK.formula 'Fe_2O_3' (mono 96) on cue 'oxide' with YK.tag 'iron (III) oxide'; atom discs 2 Fe + 3 O grouped beside it (YK.atomDisc).","tts_text":"خد الـ iron three oxide، الـ formula بتاعته قدامك.","screen_text":"iron (III) oxide Fe₂O₃","pause_after_s":0.4},{"id":"s2l13","visual":"The '(III)' in the name tag pulses on cue 'three'; a small coral ✕ (YK.wrongMark) between the '(III)' and the disc group on cue 'بتعد' (it is not a count); the name tag pulses again on cue 'الاسم'.","tts_text":"الـ three اللي في اسمه مش بتعِدّ atoms، دي جزء من الاسم.","screen_text":"(III)","pause_after_s":0.4},{"id":"s2l14","visual":"YK.predictCard(ctx, t, {at: YK.cue('s2l14'), until: YK.cue('s2l15') + 0.4, think: YK.cueEnd('s2l14'), end: YK.cue('s2l15'), kind: 'PREDICT', q: 'Fe = 56, O = 16. Mass of 1 mole of Fe2O3?'}) (lesson hook); only the question shows during the pause.","tts_text":"تفتكر one mole منه كتلته كام gram؟ وقّف وفكّر.","screen_text":"Fe₂O₃: 1 mole = ? g","pause_after_s":3},{"id":"s2l15","visual":"YK.mythLine(ctx, t, {at: YK.cue('s2l15'), wrongAt: YK.cueX('s2l15','غلط'), until: YK.cueEnd('s2l16'), text: '56 + 16 = 72', x: 96, y: 600}); numbers appear on their spoken words; ✕ held through s2l16 (lesson hook wrong option a).","tts_text":"ناس بتجمع fifty-six plus sixteen equals seventy-two؛ وده غلط.","screen_text":"56 + 16 = 72 ✕","pause_after_s":0.4},{"id":"s2l16","visual":"Correction, bigger: the 2 Fe discs light on cue 'two', the 3 O discs on cue 'three'; YK.rightMark (size 72) on cue 'كلهم', held into s2l17.","tts_text":"عشان الـ formula فيها two iron و three oxygen، ولازم نعِدّهم كلهم.","screen_text":"iron × 2 · oxygen × 3 ✓","pause_after_s":0.6},{"id":"s2l17","visual":"Second myth (lesson hook wrong option c): YK.mythLine {text: '2 + 3 = 5', wrongAt: YK.cueX('s2l17','غلط')}, the five discs counted with small numerals on cue 'five'; ✕ held to line end.","tts_text":"وفيه اللي بيجمع عدد الـ atoms، two plus three equals five؛ غلط برضه.","screen_text":"2 + 3 = 5 ✕","pause_after_s":0.4},{"id":"s2l18","visual":"Each disc drops onto a scale pan one by one (YK.stagger) on cue 'بيضيف', the pan's needle moves per disc; YK.rightMark (size 72) on cue 'الصح', held longer than the ✕.","tts_text":"الصح: أي atom بيضيف الـ atomic mass بتاعته للمجموع.","screen_text":"atomic mass ✓","pause_after_s":0.6},{"id":"s2l19","visual":"YK.termCard(ctx, 96, 380, {term: 'Molar mass', def: 'The sum of the atomic masses in the formula.', keys: ['sum of the atomic masses']} (the book wording stays in the lesson's KeyTerm)) on cue 'molar'. book_ref: lesson s2 KeyTerm (book Ch.2 'Feed Back' p.30).","tts_text":"ده اسمه molar mass: مجموع الـ atomic masses اللي في الـ formula كلها.","screen_text":"Molar mass: The sum of the atomic masses in the formula.","pause_after_s":0.8},{"id":"s2l20","visual":"YK.formula 'g/mol' (mono 80) pulses on cue 'grams'; the 'mole' chip from s1 flies into the unit on cue 'mole'.","tts_text":"ووحدته grams per mole، ودي اللي مكتوبة قدامك.","screen_text":"g/mol","pause_after_s":0.4},{"id":"s2l21","visual":"Recipe strip in the text panel: YK.list ['atoms × atomic mass', 'then +'] with items on cues 'عدد' and 'نجمع' (lesson 'Multiply each atomic mass by the number of its atoms. Then add.').","tts_text":"الطريقة: عدد الـ atoms times الـ atomic mass، وبعدين نجمع.","screen_text":"atoms × atomic mass, then +","pause_after_s":0.8},{"id":"s2l22","visual":"YK.formula '2Fe_2O_3 · 3H_2O' (lesson notation) builds on cue 'نقطة'; the dot and the H2O glow cyan; no name label (the ore name stays for the chapter).","tts_text":"فيه compounds جواها مَيّة، وبنكتبها بعد نقطة في الـ formula بتاعتها.","screen_text":"· H₂O","pause_after_s":0.4},{"id":"s2l23","visual":"The dot pulses (YK.pulse) on cue 'النقطة'; a small water molecule (YK.molecule 'H2O') drops onto the scale pan on cue 'ضيف'.","tts_text":"النقطة دي معناها: ضيف كتلة المَيّة كمان.","screen_text":"·","pause_after_s":0.4},{"id":"s2l24","visual":"YK.formula 'H_2O = 2 × 1 + 16 = 18' builds term by term on the spoken numbers (YK.cueX 'two', 'one', 'sixteen', 'eighteen') (lesson 'Each H2O is 2 × 1 + 16 = 18').","tts_text":"المَيّة: two times one plus sixteen equals eighteen بالظبط.","screen_text":"H₂O = 2 × 1 + 16 = 18","pause_after_s":0.4},{"id":"s2l25","visual":"In '2Fe_2O_3 · 3H_2O' the front 2 and 3 get gold YK.bracket around their whole unit on cue 'الكبير' and cue 'كلها' (lesson 'The numbers in front multiply the whole unit'); no new numbers are shown.","tts_text":"والرقم الكبير اللي قدام الوحدة، بيضرب الوحدة كلها.","screen_text":"","pause_after_s":1},{"id":"s3l2","visual":"YK.formula 'Fe_2O_3' (mono 96) top of the stage with YK.tag 'iron (III) oxide'; working lines build below it (YK.formula mono 56, left-aligned at x 840). Lesson s3 worked example.","tts_text":"نحسب الـ molar mass بتاعة الـ iron three oxide خطوة خطوة.","screen_text":"iron (III) oxide Fe₂O₃","pause_after_s":0.4},{"id":"s3l3","visual":"Line 1 'Fe: 2 × 56 = 112' builds on cues 'two', 'fifty-six', 'hundred'; the 2 Fe discs pulse.","tts_text":"الـ iron: two times fifty-six equals one hundred and twelve كده.","screen_text":"iron: 2 × 56 = 112","pause_after_s":0.4},{"id":"s3l4","visual":"Line 2 'O: 3 × 16 = 48' builds on cues 'three', 'sixteen', 'forty-eight'; the 3 O discs pulse.","tts_text":"والـ oxygen: three times sixteen equals forty-eight كده.","screen_text":"oxygen: 3 × 16 = 48","pause_after_s":0.4},{"id":"s3l5","visual":"Line 3 '112 + 48 = 160 g/mol' with YK.counter rolling to 160 on cue 'hundred' (third number word); gold underline on 'g/mol' on cue 'sixty'.","tts_text":"نجمع: one hundred and twelve plus forty-eight equals one hundred and sixty كده.","screen_text":"112 + 48 = 160 g/mol","pause_after_s":0.4},{"id":"s3l6","visual":"The scale pan returns with a heap of Fe2O3 groups; YK.label '160 g' on cue 'hundred'; answers the s2l14 predict (YK.rightMark on the predict's echo chip).","tts_text":"يعني one mole من الـ iron three oxide كتلته one hundred and sixty grams بالظبط.","screen_text":"1 mole of iron (III) oxide = 160 g","pause_after_s":1},{"id":"s3l7","visual":"YK.formula '2Fe_2O_3 · 3H_2O' replaces Fe2O3 at the top on cue 'formula'; the dot glows cyan on cue 'نقطة'.","tts_text":"وبخطوة زيادة: الـ formula دي فيها نقطة ومَيّة.","screen_text":"2Fe₂O₃·3H₂O","pause_after_s":0.4},{"id":"s3l8","visual":"Line 'Fe2O3 part: 2 × 160 = 320' builds on the spoken numbers; the front 2 bracketed with its whole Fe2O3 unit.","tts_text":"يعني two times one hundred and sixty equals three hundred and twenty كده.","screen_text":"2 × 160 = 320","pause_after_s":0.4},{"id":"s3l9","visual":"Line 'H2O part: 3 × 18 = 54' builds on the spoken numbers; the front 3 bracketed with its H2O unit.","tts_text":"والمَيّة: three times eighteen equals fifty-four كده.","screen_text":"3 × 18 = 54","pause_after_s":0.4},{"id":"s3l10","visual":"Line '320 + 54 = 374 g/mol' with YK.counter to 374 on cue 'three' (third); YK.rightMark on the total. Lesson Reveal value.","tts_text":"نجمع: three hundred and twenty plus fifty-four equals three hundred and seventy-four كده.","screen_text":"320 + 54 = 374 g/mol","pause_after_s":1},{"id":"s3l11","visual":"New case (lesson s5 FillBlank; the example was Fe2O3): the board clears; YK.formula 'FeCO_3' (mono 96) with YK.tag 'iron (II) carbonate' on cue 'carbonate'.","tts_text":"دورك: الـ iron two carbonate، احسب الـ molar mass بتاعته.","screen_text":"iron (II) carbonate FeCO₃","pause_after_s":0.4},{"id":"s3l12","visual":"YK.predictCard(ctx, t, {at: YK.cue('s3l12'), until: YK.cue('s3l13') + 0.4, think: YK.cueEnd('s3l12'), end: YK.cue('s3l13'), kind: 'QUICK CHECK', q: 'FeCO3: molar mass = ? g/mol (Fe = 56, C = 12, O = 16)'}); only the question + think ring during the 5 s silence.","tts_text":"استخدم fifty-six و twelve و sixteen؛ وقّف الفيديو واحسب.","screen_text":"Fe = 56 · C = 12 · O = 16 · ? g/mol","pause_after_s":5},{"id":"s3l13","visual":"YK.answerSlot {text: '56 + 12 + 3 × 16', at: YK.cueX('s3l13','fifty-six')}; each term appears on its spoken number; the 3 links by a gold arrow to the O of FeCO3 only.","tts_text":"الإجابة: fifty-six plus twelve plus three times sixteen كده.","screen_text":"56 + 12 + 3 × 16 ✓","pause_after_s":0.4},{"id":"s3l14","visual":"Total '= 116 g/mol' with YK.rightMark on cue 'hundred'; the C disc stays single (no ×3) with a small YK.tag 'carbon × 1' on cue 'oxygen' (the subscript belongs to O).","tts_text":"المجموع one hundred and sixteen grams per mole؛ والـ three بتعِدّ الـ oxygen لوحده.","screen_text":"116 g/mol · 3 → oxygen","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الـ chapter بتاعنا؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.tag 'mass percentage' on cue 'mass'.","tts_text":"في الـ chapter هتقابل الـ mass percentage، يعني نسبة العنصر المئوية.","screen_text":"mass percentage","pause_after_s":0.4},{"id":"s4l3","visual":"A rock chunk YK.ore(ctx, 1300, 600, 200, {seed: 4}) with a vertical gauge (ctx bar, C.atomFe, no number) filling on cue 'نسبة'; YK.tag 'molar mass' flies into the gauge on cue 'molar' (lesson 'You will use molar mass to find the percentage of iron in an ore').","tts_text":"هتستخدم الـ molar mass عشان تعرف نسبة الـ iron في الخام.","screen_text":"molar mass → iron %","pause_after_s":0.4},{"id":"s4l4","visual":"YK.chip 'Roasting' (map title) on cue 'Roasting'; the rock gets a kiln glow (YK.kiln, industry.js) on cue 'التسخين'; two empty gauges 'before' / 'after' drawn without numbers (book p.17 values stay for the chapter).","tts_text":"وفي الـ Roasting، هتقارن نسبة الـ iron قبل وبعد التسخين؛ وده في الفصل.","screen_text":"Roasting","pause_after_s":0.6},{"id":"s4l5","visual":"YK.recapCard(ctx, t, {at: YK.cue('s4l5'), until: Infinity, title: 'Molar mass', line: 'Sum of the atomic masses in the formula', formula: 'g/mol', pulse: [{word: 'Sum', at: YK.cueX('s4l5','مجموع')}]}). Recap s4l5–s4l7 ≈ 16 s.","tts_text":"الخلاصة: الـ molar mass هي مجموع الـ atomic masses اللي في الـ formula كلها.","screen_text":"Molar mass","pause_after_s":0.4},{"id":"s4l6","visual":"The recipe strip from s2l21 returns under the recap card, items pulse on cues 'subscript', 'atomic', 'واجمع'.","tts_text":"عِدّ الـ atoms من الـ subscript، اضرب في الـ atomic mass، واجمع.","screen_text":"atoms · subscript · atomic mass","pause_after_s":0.4},{"id":"s4l7","visual":"YK.takeaway(ctx, {title: 'Molar mass', line: 'Sum of the atomic masses', formula: 'g/mol', t, pulse: [{word: 'Sum', at: YK.cueX('s4l7','مجموع')}, {word: 'atomic', at: YK.cueX('s4l7','atomic')}]}) — the lock-in equals the takeaway card.","tts_text":"يعني الـ molar mass، مجموع الـ atomic masses، بالجرام لكل mole كده.","screen_text":"Molar mass = sum of the atomic masses (g/mol).","pause_after_s":1.5}],"logline":"هتعرف تحسب الـ molar mass لأي compound من الـ formula بتاعته والـ atomic masses، حتى لو فيه مية بعد نقطة.","segments":[{"id":"s1","title":"A dozen eggs and a mole of atoms","concept_id":"stoich.molar-mass"},{"id":"s2","title":"Adding up a formula: the molar mass","concept_id":"stoich.molar-mass"},{"id":"s3","title":"The molar mass of iron three oxide","concept_id":"stoich.molar-mass"},{"id":"s4","title":"Where Chapter 1 uses molar 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بتشتري بيض بتشتريه بالدستة صح\nالدستة twelve بيضة مهما كان حجم البيض\nيعني الدستة عدد ثابت مش كتلة ثابتة\nالـ iron الحديد معمول من حبيبات صغيرة جدًا\nاسمها atom يعني ذرة\nوالـ oxygen الغاز اللي بنتنفسه معمول من\natoms برضه\nالـ iron ليه رمز والـ oxygen ليه رمز زي\nاللي قدامك كده\nالـ atom ليه كتلة اسمها atomic mass الـ\niron fifty-six والـ oxygen sixteen كمان\nيعني الـ atom بتاع الـ iron أتقَل من بتاع\nالـ oxygen بكتير\nوالـ mole زي الدستة عدد ثابت من الـ atoms\nإنما ضخم جدًا\nالـ mole فيه six point zero two times ten\nto the power twenty-three بالظبط\nيعني one mole من atoms الـ iron كتلته\nfifty-six grams بالظبط\nيبقى معانا atom و atomic mass و mole\nخلّيهم في بالك\nلما atoms مختلفة تتّحد مع بعض بتعمل\ncompound زي المَيّة\nوالـ formula بتاعته بتقولك فيه كام atom من\nكل نوع\nفي المية الرقم الصغير two جنب الـ hydrogen\nيعني two atoms منه\nوالـ oxygen مالوش رقم يعني one atom لوحده\nالرقم الصغير ده اسمه subscript وبيعِد الـ\natom اللي قبله على طول\nولو قبله قوس زي الـ iron three sulphate\nبيعِد كل اللي جوا القوس\nزي مجموعة اسمها carbonate فيها one carbon\nو three oxygen معاه\nالـ three دي بتعِد الـ oxygen مش الـ\ncarbon عشان قبلها على طول\nودي الـ atomic masses اللي هنستخدمها iron\nfifty-six و oxygen sixteen كمان\nوالـ carbon twelve والـ hydrogen one دي\natomic masses مقرّبة\nخد الـ iron three oxide الـ formula بتاعته\nقدامك\nالـ three اللي في اسمه مش بتعِد atoms دي\nجزء من الاسم\nتفتكر one mole منه كتلته كام gram وقّف\nوفكّر\nناس بتجمع fifty-six plus sixteen equals\nseventy-two وده غلط\nعشان الـ formula فيها two iron و three\noxygen ولازم نعِدّهم كلهم\nوفيه اللي بيجمع عدد الـ atoms two plus\nthree equals five غلط برضه\nالصح أي atom بيضيف الـ atomic mass بتاعته\nللمجموع\nده اسمه molar mass مجموع الـ atomic masses\nاللي في الـ formula كلها\nووحدته grams per mole ودي اللي مكتوبة\nقدامك\nالطريقة عدد الـ atoms times الـ atomic\nmass وبعدين نجمع\nفيه compounds جواها مَيّة وبنكتبها بعد\nنقطة في الـ formula بتاعتها\nالنقطة دي معناها ضيف كتلة المَيّة كمان\nالمَيّة two times one plus sixteen equals\neighteen بالظبط\nوالرقم الكبير اللي قدام الوحدة بيضرب\nالوحدة كلها\nنحسب الـ molar mass بتاعة الـ iron three\noxide خطوة خطوة\nالـ iron two times fifty-six equals one\nhundred and twelve كده\nوالـ oxygen three times sixteen equals\nforty-eight كده\nنجمع one hundred and twelve plus\nforty-eight equals one hundred and sixty\nكده\nيعني one mole من الـ iron three oxide\nكتلته one hundred and sixty grams بالظبط\nوبخطوة زيادة الـ formula دي فيها نقطة\nومَيّة\nيعني two times one hundred and sixty\nequals three hundred and twenty كده\nوالمَيّة three times eighteen equals\nfifty-four كده\nنجمع three hundred and twenty plus\nfifty-four equals three hundred and\nseventy-four كده\nدورك الـ iron two carbonate احسب الـ molar\nmass بتاعته\nاستخدم fifty-six و twelve و sixteen وقّف\nالفيديو واحسب\nالإجابة fifty-six plus twelve plus three\ntimes sixteen كده\nالمجموع one hundred and sixteen grams per\nmole والـ three بتعِد الـ oxygen لوحده\nطب الكلام ده هيفيدك فين في الـ chapter\nبتاعنا\nفي الـ chapter هتقابل الـ mass percentage\nيعني نسبة العنصر المئوية\nهتستخدم الـ molar mass عشان تعرف نسبة الـ\niron في الخام\nوفي الـ Roasting هتقارن نسبة الـ iron قبل\nوبعد التسخين وده في الفصل\nالخلاصة الـ molar mass هي مجموع الـ atomic\nmasses اللي في الـ formula كلها\nعِد الـ atoms من الـ subscript اضرب في الـ\natomic mass واجمع\nيعني الـ molar mass مجموع الـ atomic\nmasses بالجرام لكل mole كده","countable":false,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":69,"see_also":[{"item_id":"chem-s3-en.lesson-fe.roasting","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Roasting of iron ore","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":137.68,"kind":"pause_question","spec":{"answer":"لازم نعد كل الـ atoms: iron × 2 و oxygen × 3، كل واحد في الـ atomic mass بتاعه، وبعدين نجمع.","prompt":"Fe₂O₃ (Fe = 56، O = 16): mole واحد منه، نحسب كتلته إزاي؟","options":[{"id":"a","text":"2 × 56 + 3 × 16","correct":true},{"id":"b","text":"56 + 16","correct":false},{"id":"c","text":"2 + 3","correct":false}],"answer_t_s":141.21,"concept_id":"stoich.molar-mass"},"content_lang":"ar-EG"},{"id":"think-2","t_s":275.15,"kind":"pause_question","spec":{"answer":"116 g/mol: 56 + 12 + 3 × 16؛ الـ 3 بتعد الـ oxygen لوحده.","prompt":"iron (II) carbonate FeCO₃ (Fe = 56، C = 12، O = 16): الـ molar mass كام؟","options":[{"id":"a","text":"116 g/mol","correct":true},{"id":"b","text":"84 g/mol","correct":false},{"id":"c","text":"252 g/mol","correct":false}],"answer_t_s":280.79,"concept_id":"stoich.molar-mass"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-stoich.molar-mass"]},{"id":"chem-s3-en.video-walkthrough-chem.natural-gas-methane","kind":"walkthrough","version":6,"ord":359,"content_lang":"ar-EG","primary_concept_id":"chem.natural-gas-methane","concepts":[{"concept_id":"chem.natural-gas-methane","role":"primary"}],"title":"Natural gas (methane): from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.natural-gas-methane v1 (s1 hook 'The blue flame': many kitchen stoves in Egypt burn natural gas, MCQ option H2 = s2 myth 2; s2 KeyTerm 'Natural gas' verbatim + chart Methane 93 / Other gases 7; s3 KeyTerm 'Hydrocarbon' verbatim + 'Methane has one C atom, so it is the simplest hydrocarbon'; s4 Classify (CO2, CO sorted as non-hydrocarbons = s2 myth 1) + FillBlank 2CH4 -> 2 C, 8 H with mistake 2+4=6 (s3l6); s5 recap 'A number in front of a formula multiplies every atom in it' (s2l24 verbatim) and note 'In the Midrex furnace, natural gas is turned into the gases that reduce iron ore' (s4l3-4)); concept chem.natural-gas-methane v2 (no recorded misconceptions: s2 refutes the lesson's two check mistakes); dependent fe.midrex-reduction (title used verbatim on the s4 chip; its mc1 'methane itself reduces the ore' is respected: s4 says the gas is turned into other gases that do the job, details left to the chapter); book p.18 'natural gas (93% methane) in the midrex furnace' and the equation starting 2CH4 (only '2CH4 + …' shown, no full equation). Terms (defined at first use): s1 natural gas, atom, molecule (3); s2 methane, carbon, hydrogen, formula, compound, hydrocarbon, oxygen, carbon dioxide. s3/s4 introduce none except the dependent's title (reduction, Midrex furnace) named with a plain gloss ('a furnace that makes iron'). Formulas voiced by name (CH4 = methane, 2CH4 = «اتنين methane», 3CH4 = «تلاتة methane»), letters never read. Worked example 2CH4 (book/lesson); self-check NEW case 3CH4 -> 12 hydrogen. Predicts: s2l18 (~2:05), s3l9 (~3:45). not-in-source: many homes get the gas through a pipe from underground; atoms are too small to see with the eyes; a molecule = atoms joined together; carbon is the same kind of atom as in charcoal; oxygen is in the air we breathe; carbon dioxide (one carbon, two oxygen) is what we breathe out; compound = two or more kinds of atoms joined; the name hydrocarbon comes from hydrogen + carbon; 3CH4 has 12 hydrogen atoms; the Midrex furnace makes iron. Estimated duration ≈ 296 s (≈ 4:56; 591 words at ~2.4 words/s + 41.6 s pauses + joins); planning aid only.","title":"Natural gas (methane): from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"Camera (YK.camera) pushes in on the burner from cue 'افتكر'; the flame grows (ring radius tween) and brightens on cue 'الزرقا'; YK.fpara 'The blue flame' (48) in the text panel (96, 260) on cue 'النار'.","tts_text":"افتكر النار الزرقا اللي في بوتاجاز بيتك وإنت بتطبخ.","screen_text":"The blue flame","pause_after_s":0.4},{"id":"s1l3","visual":"YK.predictCard-style header pill only (YK.tag 'What is burning?' 48, gold) in the text panel on cue 'بيتحرق'; on the stage faint seeded YK.particles (mode 'up', C.textDim, alpha 0.3) rise from the burner on cue 'غاز' to show an invisible gas.","tts_text":"طب إيه اللي بيتحرق هناك بالظبط؟ غاز مش بنشوفه بعينينا.","screen_text":"What is burning?","pause_after_s":0.6},{"id":"s1l4","visual":"Picture change: the camera pulls back and down; a cutaway of the ground (dark layered bands, ctx rects, C.night/C.steelDark) with an underground pocket (rounded ctx path) at y 900; a pipe (ctx stroke 18 px C.steel) runs from the pocket up to the burner, a dashed C.cyan flow (YK.flyer dots along the pipe) from cue 'ماسورة'; the pocket glows on cue 'الأرض'.","tts_text":"في بيوت كتير، الغاز ده جاي في ماسورة من تحت الأرض.","screen_text":"From underground, by pipe","pause_after_s":0.4},{"id":"s1l5","visual":"YK.termCard(ctx, 96, 380, {term: 'natural gas', align: 'left', p: on cue 'natural'}) + YK.fpara 'a gas fuel found underground' (40, textDim) under it on cue 'وقود'; YK.tag 'natural gas' (40) on the pocket on cue 'natural'.","tts_text":"الغاز ده اسمه natural gas، وقود بنطلّعه من تحت الأرض.","screen_text":"natural gas","pause_after_s":0.6},{"id":"s1l6","visual":"YK.zoomThrough(ctx, t, {from: drawPipe, to: drawSwarm, focus: pipe centre, badge: '×10^8'}) starting on cue 'كبّرنا'; the inside opens into a dark field of small grey dots (YK.particles mode 'float', seed 4, count 30, C.textDim) moving on cue 'بتتحرك'. YK.scaleBadge(ctx, null, null, {text: '×10^8'}) in the stage corner.","tts_text":"لو كبّرنا الغاز ده جدًا، هنلاقيه حتت صغيرة أوي بتتحرك.","screen_text":"Zoom in ×10^8","pause_after_s":0.4},{"id":"s1l7","visual":"One moving dot (a CH4 molecule, YK.molecule labels:false) grows and opens into its small discs on cue 'متركبة', then one disc grows into YK.atomDisc(ctx, 1307, 560, 90, {el: 'C', symbol: false, color: C.steel}) on cue 'atom' (no symbol yet: kinds come later); YK.termCard(ctx, 96, 380, {term: 'atom', align: 'left'}) on cue 'atom' + YK.fpara 'a tiny building piece' (40, textDim).","tts_text":"كل حتة منهم متركبة من حتت أصغر، الواحدة اسمها atom، ومش بنشوفها.","screen_text":"atom: a tiny building piece","pause_after_s":0.4},{"id":"s1l8","visual":"Three YK.atomDisc side by side (x 1050 / 1307 / 1560, y 600, r 70, symbol: false): dark grey (atomC colour), white (H colour), red (O colour via YK.atomColor) pop in left → right (YK.stagger) on cue 'أنواع'; a gold YK.bracket around the three on cue 'بالألوان'. Unlabelled on purpose: their names come in The idea.","tts_text":"والـ atoms دي أنواع مختلفة، وهنا بنميّز الأنواع بالألوان.","screen_text":"Atoms: different kinds, different colours here","pause_after_s":0.4},{"id":"s1l9","visual":"The dark disc and two white discs slide together and short bond sticks (#F4F2FF 60%) draw between them on cue 'يرتبطوا' (generic YK.molecule with atoms:[…] in r units, labels:false); YK.termCard(ctx, 96, 380, {term: 'molecule', align: 'left'}) on cue 'molecule' + YK.fpara 'atoms joined together' (40, textDim).","tts_text":"ولما كام atom يرتبطوا ببعض، يعملوا molecule، يعني جزيء.","screen_text":"molecule: atoms joined together","pause_after_s":0.4},{"id":"s1l10","visual":"Zoom back out to the pipe cutaway: the pipe interior fills with a seeded drift of small unlabelled CH4 molecules (YK.molecule formula 'CH4', r 16, labels:false, ×12, moving along the pipe with t) on cue 'molecules'; tags 'natural gas' (40) on the pipe on cue 'natural', 'molecules' (36) on one molecule on cue 'molecules'.","tts_text":"والـ natural gas نفسه عبارة عن molecules كتير بتِجري في الماسورة.","screen_text":"natural gas: many molecules","pause_after_s":0.4},{"id":"s1l11","visual":"Micro-recap: the three term cards collapse into three YK.chip kind 'concept' in a row in the text panel (96, 300 / 420 / 540) on the cues 'natural', 'atom', 'molecule'; stage thumbnails (pipe, one disc, one molecule) light in the same order (YK.pulse).","tts_text":"يبقى معانا تلات كلمات: natural gas و atom و molecule، خلّيهم في بالك.","screen_text":"natural gas · atom · molecule","pause_after_s":1},{"id":"s2l2","visual":"Stage: the pipe swarm of s1l10 returns; most molecules turn cyan-outlined (YK.pulse on each, staggered) on cue 'معظم', a few stay grey; YK.tag 'methane' (44, cyan) on one cyan molecule on cue 'methane'; text panel YK.fpara 'natural gas: mostly methane molecules' (44) builds on cues 'natural' / 'methane'.","tts_text":"معظم الـ natural gas نوع واحد من الـ molecules، اسمه methane كده.","screen_text":"natural gas: mostly methane molecules","pause_after_s":0.4},{"id":"s2l3","visual":"Picture change: the lesson's chart as YK.chart(ctx, 860, 200, 900, 700, {type: 'bar', data: [{x: 'Methane', y: 93}, {x: 'Other gases', y: 7}], yLabel: 'Percentage', values: true, grow: from cue 'ninety-three' to cue 'المية'}); the 'Other gases' bar grows on cue 'seven'; 'Methane' bar highlighted cyan (highlight:['Methane']) on cue 'methane'. Book p.18: natural gas (93% methane).","tts_text":"الكتاب بيقول: ninety-three percent methane، والـ seven percent الباقيين غازات تانية.","screen_text":"Methane 93% · Other gases 7%","pause_after_s":0.6},{"id":"s2l4","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 360, {term: 'Natural gas', def: 'A gas fuel found underground. Its main part is methane, CH4.', keys: ['methane'], align: 'left', p: on cue 'natural'}); the chart shrinks to the stage top-right (scale 0.5) and stays.","tts_text":"الـ natural gas وقود من تحت الأرض، وأهمه الـ methane ده.","screen_text":"Natural gas: A gas fuel found underground. Its main part is methane, CH₄.","pause_after_s":0.8},{"id":"s2l5","visual":"Picture change: one methane molecule zooms up to fill the stage (camera push); everything but its centre is hidden; YK.atomDisc(ctx, 1307, 580, 110, {el: 'C'}) (C, atomC dark grey, symbol on) pops in on cue 'atom'; YK.tag 'carbon' (44) under it on cue 'carbon'.","tts_text":"في نص الـ molecule بتاع الـ methane فيه one atom اسمه carbon كده.","screen_text":"methane molecule: 1 carbon atom","pause_after_s":0.4},{"id":"s2l6","visual":"Inset YK.panel(ctx, 1460, 220, 340, 280): a charcoal lump (YK.ore(ctx, 1630, 360, 110, {seed: 7}) in near-black, matte) on cue 'الفحم'; a thin gold line links the inset to the C disc on cue 'نوع'; YK.fpara 'carbon: as in charcoal' (40) in the text panel on cue 'carbon'.","tts_text":"الـ carbon ده نفس نوع الـ atom اللي في الفحم الأسود.","screen_text":"carbon: as in charcoal","pause_after_s":0.4},{"id":"s2l7","visual":"Inset out; four white YK.atomDisc(el 'H', r 68) fly in from the four stage corners (YK.flyer, short trails) on cue 'four' and lock onto the C with bond sticks (completing YK.molecule({formula: 'CH4', r: 110}) geometry); tag 'hydrogen' (44) on one H on cue 'hydrogen'; small counter tags 1–4 pop on each H in turn (YK.stagger) between 'four' and 'hydrogen'.","tts_text":"وحواليه four atoms من نوع تاني اسمه hydrogen، خفاف وصغيرين.","screen_text":"4 hydrogen atoms around it","pause_after_s":0.4},{"id":"s2l8","visual":"YK.termCard(ctx, 96, 380, {term: 'formula', align: 'left'}) on cue 'formula'; above the molecule YK.formula(ctx, 'CH4', 1307, 260, {size: 96, align: 'center'}) reveals left → right on cue 'مختصرة'.","tts_text":"وبنكتب الـ methane بطريقة مختصرة، اسمها الـ formula بتاعته.","screen_text":"formula of methane: CH₄","pause_after_s":0.4},{"id":"s2l9","visual":"Gold arrows (YK.flow edges, curve 0.2) from the 'C' of the formula down to the C disc on cue 'carbon', and from the 'H' to the H discs on cue 'hydrogen'; the 'C' and 'H' glyphs pulse gold (YK.formula '!{C}' accent) on the same cues; tags 'carbon' / 'hydrogen' (40) stay on the discs.","tts_text":"أول حرف في الـ formula رمز الـ carbon، والتاني رمز الـ hydrogen كده.","screen_text":"C: carbon · H: hydrogen","pause_after_s":0.4},{"id":"s2l10","visual":"The subscript '4' of the formula scales up 1.4× and glows gold (YK.formula 'CH_{!{4}}') on cue 'four'; the four H discs flash one by one (YK.stagger, gap 0.2) from cue 'بتعدّ'; YK.fpara 'small 4: 4 hydrogen atoms' (44) in the text panel.","tts_text":"والـ four الصغيرة اللي تحت بتعِدّ الـ atoms بتاعة الـ hydrogen كده.","screen_text":"small 4: 4 hydrogen atoms","pause_after_s":0.4},{"id":"s2l11","visual":"An empty dashed slot (YK.bracket, dashed, C.textDim) appears after the 'C' of the formula on cue 'رقم'; a ghost '1' (C.textDim, 60% size) fades into the slot on cue 'one' while the single C disc pulses; YK.fpara 'no small number after C: 1 carbon atom' (40).","tts_text":"والـ carbon مكتوب من غير رقم، يعني فيه one atom منه بس.","screen_text":"no small number after C: 1 carbon atom","pause_after_s":0.4},{"id":"s2l12","visual":"The C disc (dark) and H discs (white) get two colour brackets (YK.bracket, cyan around C, mint around the Hs) on cue 'نوعين'; bond sticks glow (YK.glow) on 'مرتبطين'; YK.termCard(ctx, 96, 380, {term: 'compound', align: 'left'}) on cue 'compound' + YK.fpara 'two or more kinds of atoms joined' (40, textDim).","tts_text":"ولأن الـ methane فيه نوعين atoms مرتبطين ببعض، اسمه compound كده.","screen_text":"compound: two or more kinds of atoms joined","pause_after_s":0.4},{"id":"s2l13","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 360, {term: 'Hydrocarbon', def: 'A compound made of carbon and hydrogen only.', keys: ['carbon', 'hydrogen', 'only'], align: 'left', p: on cue 'hydrocarbon'}); 'only' turns gold on cue 'وبس'; on the stage the CH4 molecule gets tag 'hydrocarbon' (44, gold) on cue 'hydrocarbon'.","tts_text":"والـ compound اللي فيه carbon و hydrogen وبس، اسمه hydrocarbon كده.","screen_text":"Hydrocarbon: A compound made of carbon and hydrogen only.","pause_after_s":0.8},{"id":"s2l14","visual":"Word build in the stage: 'hydrogen' (mint) and 'carbon' (cyan) as two YK.tag pills slide together on cues 'hydrogen' / 'carbon' and merge into one word 'hydrocarbon' (gold, 64) with the 'hydro' part mint and 'carbon' part cyan (YK.formula '!{…}' accents) on cue 'شُفت؟'.","tts_text":"الاسم hydrocarbon نفسه متركب من الـ hydrogen والـ carbon، شُفت؟","screen_text":"hydrogen + carbon → hydrocarbon","pause_after_s":0.4},{"id":"s2l15","visual":"The CH4 molecule returns centre-stage; its single C disc gets a gold '1 carbon' tag (YK.tag, gold) on cue 'one'; YK.fpara 'Methane: the simplest hydrocarbon' (48) in the text panel on cue 'أبسط' (lesson s3: one C atom → simplest).","tts_text":"والـ methane أبسط hydrocarbon، عشان فيه one carbon بس.","screen_text":"Methane: the simplest hydrocarbon (1 carbon)","pause_after_s":0.6},{"id":"s2l16","visual":"Picture change: methane slides to the stage left (dim 35%); a red YK.atomDisc(ctx, 1500, 560, 90, {el: 'O'}) pops in on cue 'oxygen' with soft air swirls (YK.particles mode 'float', C.cyan, alpha 0.25) on 'الهوا'; YK.termCard(ctx, 96, 380, {term: 'oxygen', align: 'left'}) on cue 'oxygen' + YK.fpara 'in the air we breathe' (40, textDim).","tts_text":"فيه نوع atom تالت اسمه oxygen، اللي في الهوا اللي بنتنفسه.","screen_text":"oxygen: in the air we breathe","pause_after_s":0.4},{"id":"s2l17","visual":"YK.molecule(ctx, 1500, 580, {formula: 'CO2', r: 80}) builds: C disc on cue 'carbon'#1, the two O discs on cue 'two'; label 'carbon dioxide' + YK.formula 'CO2' (mono 56) above it on cue 'dioxide'; small breath puffs (YK.particles from the left edge) on 'النفس'.","tts_text":"والـ carbon dioxide اللي بنطلّعه في النفس، فيه one carbon و two oxygen كمان.","screen_text":"carbon dioxide CO₂: 1 carbon + 2 oxygen","pause_after_s":0.4},{"id":"s2l18","visual":"YK.predictCard(ctx, t, {at: YK.cue('s2l18'), until: YK.cue('s2l19') + 0.4, think: YK.cueEnd('s2l18'), end: YK.cue('s2l19'), kind: 'PREDICT', q: 'Carbon dioxide has carbon. Is it a hydrocarbon?'}); the CO2 molecule's C disc pulses on cue 'carbon'#2. Think ring runs through the 3 s silence; nothing answered on screen during it.","tts_text":"الـ carbon dioxide فيه carbon، يبقى hydrocarbon ولا لأ؟ فكّر.","screen_text":"PREDICT: carbon dioxide has carbon. Hydrocarbon?","pause_after_s":3},{"id":"s2l19","visual":"Answer: the two O discs of CO2 flash coral (YK.pulse) on cue 'oxygen'; YK.answerSlot(ctx, t, {at: YK.cueX('s2l19','لأ'), text: 'No: carbon dioxide has oxygen', x: 420, y: 760}); tag 'not a hydrocarbon' would add words: none.","tts_text":"لأ، الـ carbon dioxide فيه oxygen، يعني مش carbon و hydrogen بس.","screen_text":"No: carbon dioxide has oxygen ✓","pause_after_s":0.6},{"id":"s2l20","visual":"Misconception (the lesson's sort mistake: CO2 / CO sorted as hydrocarbons): YK.mythLine(ctx, t, {at: YK.cue('s2l20'), wrongAt: YK.cueX('s2l20','غلط'), until: YK.cueEnd('s2l21') + 1.5, text: 'Has carbon → hydrocarbon', x: 96, y: 300, size: 48}) — coral with ✕ (YK.wrongMark) from the «غلط» cue for its whole visible time; no strike-through. Stage: a ghost 'hydrocarbon' tag over the CO2 molecule crossed by YK.wrongMark(ctx, 1500, 400, 110) on the same cue.","tts_text":"فيه ناس فاكرة إن أي حاجة فيها carbon تبقى hydrocarbon، وده غلط.","screen_text":"Has carbon → hydrocarbon","pause_after_s":0.4},{"id":"s2l21","visual":"Fix (held ≥ the myth): methane (left, full brightness) gets YK.rightMark on cue 'hydrocarbon'; CO2 (right) keeps its coral O flash; YK.fpara 'Hydrocarbon: carbon and hydrogen, nothing else' (44, mint, 96, 420) + YK.rightMark beside it on cue 'تالت'. The myth line stays visible with its ✕ above it.","tts_text":"الـ hydrocarbon لازم يبقى فيه carbon و hydrogen، ومفيش أي نوع تالت.","screen_text":"Hydrocarbon: carbon and hydrogen, nothing else ✓","pause_after_s":0.6},{"id":"s2l22","visual":"Second misconception (lesson hook option a: hydrogen, H2): picture change; YK.mythLine(ctx, t, {at: YK.cue('s2l22'), wrongAt: YK.cueX('s2l22','غلط'), until: YK.cueEnd('s2l23') + 1.5, text: 'Natural gas is mostly hydrogen', x: 96, y: 300, size: 44}) with ✕ for its whole visible time; stage: a pair of loose H discs (YK.molecule formula 'H2', r 50) drifting in the pipe, crossed by YK.wrongMark on cue 'غلط'.","tts_text":"وفيه اللي فاكر إن الـ natural gas أغلبه غاز hydrogen، وده غلط برضه.","screen_text":"Natural gas is mostly hydrogen ✕","pause_after_s":0.4},{"id":"s2l23","visual":"Fix (held ≥ the myth): the loose H2 fades; a CH4 molecule (YK.molecule formula 'CH4', r 80) beside it, its four bond sticks glow gold on cue 'مرتبط'; tags 'hydrogen' on an H and 'carbon' on the C on their cues, 'methane' (44) under it on cue 'methane'; YK.fpara 'Its hydrogen is joined to carbon in methane' (40, mint) + YK.rightMark on cue 'لوحده'. Myth line + ✕ stay above.","tts_text":"الـ hydrogen ده مرتبط مع الـ carbon جوه الـ methane، مش غاز لوحده.","screen_text":"Its hydrogen is joined to carbon in methane ✓","pause_after_s":0.6},{"id":"s2l24","visual":"Lesson recap wording on a YK.panel in the text panel (YK.fpara 44, 'multiplies' gold). Stage: YK.formula 'CH4' (mono 88) with an empty gold dashed slot in front of it (YK.bracket) on cue 'قدام'; the CH4 molecule under it duplicates into a row of copies (fade-in, no count shown) on cue 'molecules'; every atom of the copies pulses once on cue 'فبيضرب'. No number drawn yet (the example gives it).","tts_text":"والرقم الكبير قدام الـ formula بيعِدّ الـ molecules، فبيضرب الـ atoms اللي جواها.","screen_text":"A number in front of a formula multiplies every atom in it.","pause_after_s":1},{"id":"s3l2","visual":"Stage: YK.formula(ctx, '2CH4', 1307, 300, {size: 110, align: 'center'}) on cue 'two'; the '2' glows gold on cue 'كده'. Steps will stack in the text panel (YK.list, LTR, 96, 300).","tts_text":"في الكتاب هتقابل two methane مكتوبين كده، يعني إيه؟","screen_text":"From the book: 2CH₄","pause_after_s":0.6},{"id":"s3l3","visual":"Two YK.molecule(…, {formula: 'CH4', r: 70}) side by side under the formula (x 1100 / 1500, y 680) pop in one after the other on cues 'two#1'#2 and 'molecules'; YK.list item 1 '2 in front: 2 methane molecules' on cue 'معناها'.","tts_text":"الـ two الكبيرة اللي قدام معناها two molecules من الـ methane كده.","screen_text":"2 in front: 2 methane molecules","pause_after_s":0.4},{"id":"s3l4","visual":"Both C discs glow cyan (YK.pulse) on cue 'carbon'; YK.list item 2 'carbon: 2 x 1 = 2' via YK.formula (× drawn as a path: Cairo lacks ×) builds on cues 'two'#1 / 'one' / 'two'#2; a gold YK.counter 0 → 2 next to the C discs on the last cue.","tts_text":"نعِدّ الـ carbon الأول: two times one equals two بالظبط.","screen_text":"carbon: 2 × 1 = 2","pause_after_s":0.4},{"id":"s3l5","visual":"All eight H discs flash mint one by one (YK.stagger, gap 0.12) from cue 'four'; YK.list item 3 'hydrogen: 2 x 4 = 8' builds on cues 'two' / 'four' / 'eight'; YK.counter 0 → 8 beside the H discs on cue 'eight'.","tts_text":"وبعدين الـ hydrogen: two times four equals eight atoms كده.","screen_text":"hydrogen: 2 × 4 = 8","pause_after_s":0.4},{"id":"s3l6","visual":"Common slip (lesson FillBlank mistake m3): YK.mythLine(ctx, t, {at: YK.cue('s3l6'), wrongAt: YK.cueX('s3l6','six'), until: YK.cueEnd('s3l7') + 1, text: '2 + 4 = 6', x: 96, y: 760, size: 44}) with ✕ for its whole visible time (no strike-through); 'multiply' + YK.rightMark (mint, 44) beside it on cue 'بيضرب', held as long.","tts_text":"خلّي بالك: الرقم اللي قدام بيضرب، مش بيجمع، فالنتيجة مش six خالص.","screen_text":"2 + 4 = 6 ✕ · multiply ✓","pause_after_s":0.4},{"id":"s3l7","visual":"Result: YK.answerSlot(ctx, t, {at: YK.cueX('s3l7','يعني'), text: '2 carbon + 8 hydrogen', x: 420, y: 900}); on the stage the two molecules group under one gold YK.bracket labelled '2CH4' on cue 'methane'; C discs cyan on 'carbon', H discs mint on 'hydrogen'.","tts_text":"يعني two methane فيهم two carbon، و eight hydrogen مع بعض.","screen_text":"2CH₄: 2 carbon + 8 hydrogen","pause_after_s":0.4},{"id":"s3l8","visual":"Tag 'hydrocarbon' (44, gold) on the bracket on cue 'hydrocarbon'; YK.rightMark small on cue 'برضه'; YK.list item 4 'Still only carbon and hydrogen → hydrocarbon'.","tts_text":"والعدد مش بيغيّر النوع: لسه carbon و hydrogen بس، يعني hydrocarbon برضه.","screen_text":"Still only carbon and hydrogen → hydrocarbon","pause_after_s":0.6},{"id":"s3l9","visual":"Self-check on a NEW case (the example was 2CH4): stage clears; YK.formula '3CH4' (mono 110) on cue 'three'. YK.predictCard(ctx, t, {at: YK.cue('s3l9'), until: YK.cue('s3l10') + 0.4, think: YK.cueEnd('s3l9'), end: YK.cue('s3l10'), kind: 'QUICK CHECK', q: 'Your turn: 3CH4 · how many hydrogen?'}); YK.checkPause(ctx, 1307, 760, {t, start: YK.cueEnd('s3l9'), dur: 4}) think ring + countdown; only the question shows during the pause (no molecules drawn, no hint).","tts_text":"دورك: three methane، فيهم كام atom من الـ hydrogen؟ وقّف وفكّر.","screen_text":"Your turn: 3CH₄ · how many hydrogen?","pause_after_s":4},{"id":"s3l10","visual":"Answer: three CH4 molecules pop in under the formula (x 1050 / 1307 / 1560) on cue 'molecules'; their twelve H discs flash mint one by one (YK.stagger) from cue 'four'; YK.answerSlot(ctx, t, {at: YK.cueX('s3l10','الإجابة'), text: '12 hydrogen (3 x 4)', x: 420, y: 700}).","tts_text":"الإجابة twelve: three molecules times four hydrogen equals twelve بالظبط.","screen_text":"12 hydrogen ✓ (3 × 4)","pause_after_s":0.4},{"id":"s3l11","visual":"Reason: in the formula '3CH4' the big '3' and the subscript '4' glow gold in turn (YK.formula '!{3}CH_{!{4}}') on cues 'three' / 'four'; YK.fpara '3 x 4 = 12' (× as a path, mono 56, mint) builds under the answer on cue 'بيضرب'.","tts_text":"السبب: الرقم الكبير three بيضرب في الرقم الصغير four اللي جوه.","screen_text":"The big 3 multiplies the small 4: 3 × 4 = 12","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, 'Reduction in the Midrex furnace', {kind: 'concept', align: 'left'}) (map title_en exactly) on cue 'reduction'; a simple tall furnace silhouette (page-local ctx path, C.steelDark, warm YK.glowCircle C.heatRed inside) on cue 'فرن'; a grey iron bar (YK.cube, C.steel, no label) slides out at its base on cue 'حديد'.","tts_text":"في الفصل فيه درس اسمه الـ reduction في الـ Midrex furnace، فرن بيعمل حديد.","screen_text":"Reduction in the Midrex furnace","pause_after_s":0.4},{"id":"s4l2a","visual":"YK.termCard(ctx, 96, 380, {term: 'reduction', align: 'left'}) on cue 'reduction' + YK.fpara 'getting the iron out of the rock' (40, textDim); on the stage a grey rock lump (YK.ore(ctx, 1307, 300, 110, {seed: 3})) drops into the furnace top on cue 'الصخر' and the iron bar slides out on cue 'نطلّع'.","tts_text":"والـ reduction هنا معناه إننا نطلّع الحديد من الصخر اللي هو جواه.","screen_text":"reduction here: getting the iron out of the rock","pause_after_s":0.4},{"id":"s4l3","visual":"YK.flow(ctx, {layout: 'row', area: {x: 820, y: 460, w: 1000, h: 200}, nodes: [{id: 'g', label: 'natural gas (93% methane)'}, {id: 'o', label: 'other gases'}], edges: [{from: 'g', to: 'o'}], reveal: from cue 'natural' to cue 'تانية'}); the methane molecule icon (YK.molecule CH4, r 30) sits in the first node on cue 'methane'. No equation, no gas names (the chapter teaches them).","tts_text":"هناك الـ natural gas، ninety-three percent methane، بيتحوّل لغازات تانية.","screen_text":"natural gas (93% methane) → other gases","pause_after_s":0.4},{"id":"s4l4","visual":"An arrow from 'other gases' to the furnace silhouette lights on cue 'بتطلّع' and the iron bar glows (YK.glow) on 'الحديد'; YK.fpara 'details in the chapter' (40, textDim) on cue 'وتفاصيلها'. Nothing more drawn (lesson recap note: natural gas is turned into the gases that reduce the ore).","tts_text":"والغازات التانية دي هي اللي بتطلّع الحديد، وتفاصيلها هتعرفها في الفصل.","screen_text":"These gases do the job: details in the chapter","pause_after_s":0.4},{"id":"s4l5","visual":"Only the first term is shown: YK.formula '2CH4 + …' (mono 72) on a YK.panel, the '2CH4' part pulsing gold on cue 'two'; a small callback of the s3 result ('2 carbon + 8 hydrogen', 36, mint) slides under it on cue 'تعدّ'. Book p.18 Midrex equation starts with 2CH4 (lesson s4 FillBlank).","tts_text":"وفي الكتاب هتقابل two methane تاني، وإنت خلاص بتعرف تعدّ الـ atoms بتاعتها.","screen_text":"In the book: 2CH₄ + … · count its atoms","pause_after_s":0.6},{"id":"s4l6","visual":"Recap (s4l6–s4l7 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l6'), until: YK.cue('s4l8'), title: 'Natural gas (methane)', line: 'Mostly methane, CH4: the simplest hydrocarbon', pulse: [{word: 'methane', at: YK.cueX('s4l6','methane')}, {word: 'hydrocarbon', at: YK.cueX('s4l6','hydrocarbon')}]}); stage: the CH4 molecule of s2 returns, small, rotating slowly.","tts_text":"الخلاصة: الـ natural gas أغلبه methane، وده أبسط hydrocarbon خالص.","screen_text":"Natural gas: mostly methane, CH₄","pause_after_s":0.4},{"id":"s4l7","visual":"Same recap card, second line 'Hydrocarbon: carbon and hydrogen only · a number in front multiplies' added on cue 'hydrocarbon'; the '2CH4' formula ghost pulses on cue 'بيضرب'.","tts_text":"والـ hydrocarbon فيه carbon و hydrogen بس، والرقم اللي قدام بيضرب.","screen_text":"Hydrocarbon: carbon and hydrogen only · a number in front multiplies","pause_after_s":0.6},{"id":"s4l8","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Natural gas (methane)', line: 'Natural gas is mostly methane, the simplest hydrocarbon.', formula: 'CH4', t, pulse: [{word: 'Natural', at: YK.cueX('s4l8','natural')}, {word: 'methane', at: YK.cueX('s4l8','methane')}, {word: 'hydrocarbon', at: YK.cueX('s4l8','hydrocarbon')}]}) held ≥ 2.5 s; no fade to black, no outro.","tts_text":"يعني الـ natural gas أغلبه methane، أبسط hydrocarbon كده.","screen_text":"Natural gas is mostly methane, the simplest hydrocarbon.","pause_after_s":1.5}],"logline":"هتعرف إن الـ natural gas أغلبه methane، وإن الـ methane أبسط hydrocarbon، وهتعدّ الـ atoms في formula زي اتنين methane.","segments":[{"id":"s1","title":"The blue flame of the stove","concept_id":"chem.natural-gas-methane"},{"id":"s2","title":"Methane, the simplest hydrocarbon","concept_id":"chem.natural-gas-methane"},{"id":"s3","title":"Counting the atoms in 2CH4","concept_id":"chem.natural-gas-methane"},{"id":"s4","title":"Where Chapter 1 uses natural 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النار الزرقا اللي في بوتاجاز بيتك\nوإنت بتطبخ\nطب إيه اللي بيتحرق هناك بالظبط غاز مش\nبنشوفه بعينينا\nفي بيوت كتير الغاز ده جاي في ماسورة من تحت\nالأرض\nالغاز ده اسمه natural gas وقود بنطلّعه من\nتحت الأرض\nلو كبّرنا الغاز ده جدًا هنلاقيه حتت صغيرة\nأوي بتتحرك\nكل حتة منهم متركبة من حتت أصغر الواحدة\nاسمها atom ومش بنشوفها\nوالـ atoms دي أنواع مختلفة وهنا بنميّز\nالأنواع بالألوان\nولما كام atom يرتبطوا ببعض يعملوا molecule\nيعني جزيء\nوالـ natural gas نفسه عبارة عن molecules\nكتير بتِجري في الماسورة\nيبقى معانا تلات كلمات natural gas و atom و\nmolecule خلّيهم في بالك\nمعظم الـ natural gas نوع واحد من الـ\nmolecules اسمه methane كده\nالكتاب بيقول ninety-three percent methane\nوالـ seven percent الباقيين غازات تانية\nالـ natural gas وقود من تحت الأرض وأهمه\nالـ methane ده\nفي نص الـ molecule بتاع الـ methane فيه\none atom اسمه carbon كده\nالـ carbon ده نفس نوع الـ atom اللي في\nالفحم الأسود\nوحواليه four atoms من نوع تاني اسمه\nhydrogen خفاف وصغيرين\nوبنكتب الـ methane بطريقة مختصرة اسمها الـ\nformula بتاعته\nأول حرف في الـ formula رمز الـ carbon\nوالتاني رمز الـ hydrogen كده\nوالـ four الصغيرة اللي تحت بتعِد الـ atoms\nبتاعة الـ hydrogen كده\nوالـ carbon مكتوب من غير رقم يعني فيه one\natom منه بس\nولأن الـ methane فيه نوعين atoms مرتبطين\nببعض اسمه compound كده\nوالـ compound اللي فيه carbon و hydrogen\nوبس اسمه hydrocarbon كده\nالاسم hydrocarbon نفسه متركب من الـ\nhydrogen والـ carbon شُفت\nوالـ methane أبسط hydrocarbon عشان فيه one\ncarbon بس\nفيه نوع atom تالت اسمه oxygen اللي في\nالهوا اللي بنتنفسه\nوالـ carbon dioxide اللي بنطلّعه في النفس\nفيه one carbon و two oxygen كمان\nالـ carbon dioxide فيه carbon يبقى\nhydrocarbon ولا لأ فكّر\nلأ الـ carbon dioxide فيه oxygen يعني مش\ncarbon و hydrogen بس\nفيه ناس فاكرة إن أي حاجة فيها carbon تبقى\nhydrocarbon وده غلط\nالـ hydrocarbon لازم يبقى فيه carbon و\nhydrogen ومفيش أي نوع تالت\nوفيه اللي فاكر إن الـ natural gas أغلبه\nغاز hydrogen وده غلط برضه\nالـ hydrogen ده مرتبط مع الـ carbon جوه\nالـ methane مش غاز لوحده\nوالرقم الكبير قدام الـ formula بيعِد الـ\nmolecules فبيضرب الـ atoms اللي جواها\nفي الكتاب هتقابل two methane مكتوبين كده\nيعني إيه\nالـ two الكبيرة اللي قدام معناها two\nmolecules من الـ methane كده\nنعِد الـ carbon الأول two times one equals\ntwo بالظبط\nوبعدين الـ hydrogen two times four equals\neight atoms كده\nخلّي بالك الرقم اللي قدام بيضرب مش بيجمع\nفالنتيجة مش six خالص\nيعني two methane فيهم two carbon و eight\nhydrogen مع بعض\nوالعدد مش بيغيّر النوع لسه carbon و\nhydrogen بس يعني hydrocarbon برضه\nدورك three methane فيهم كام atom من الـ\nhydrogen وقّف وفكّر\nالإجابة twelve three molecules times four\nhydrogen equals twelve بالظبط\nالسبب الرقم الكبير three بيضرب في الرقم\nالصغير four اللي جوه\nطب الكلام ده هيفيدك فين في الفصل\nفي الفصل فيه درس اسمه الـ reduction في الـ\nMidrex furnace فرن بيعمل حديد\nوالـ reduction هنا معناه إننا نطلّع الحديد\nمن الصخر اللي هو جواه\nهناك الـ natural gas ninety-three percent\nmethane بيتحوّل لغازات تانية\nوالغازات التانية دي هي اللي بتطلّع الحديد\nوتفاصيلها هتعرفها في الفصل\nوفي الكتاب هتقابل two methane تاني وإنت\nخلاص بتعرف تعد الـ atoms بتاعتها\nالخلاصة الـ natural gas أغلبه methane وده\nأبسط hydrocarbon خالص\nوالـ hydrocarbon فيه carbon و hydrogen بس\nوالرقم اللي قدام بيضرب\nيعني الـ natural gas أغلبه methane أبسط\nhydrocarbon كده","countable":false,"session_id":"chem-s3-en.ch1.s6","session_no":6,"session_ord":70,"see_also":[{"item_id":"chem-s3-en.lesson-fe.midrex-reduction","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Reduction in the Midrex furnace","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":146.6,"kind":"pause_question","spec":{"answer":"لأ: الـ carbon dioxide فيه oxygen؛ الـ hydrocarbon فيه carbon و hydrogen من غير أي element تاني.","prompt":"الـ carbon dioxide فيه carbon: يبقى hydrocarbon؟","options":[{"id":"a","text":"لأ","correct":true},{"id":"b","text":"أيوه، عشان فيه carbon","correct":false}],"answer_t_s":150.12,"concept_id":"chem.natural-gas-methane"},"content_lang":"ar-EG"},{"id":"think-2","t_s":234.95,"kind":"pause_question","spec":{"answer":"12: الرقم الكبير 3 بيضرب في الرقم الصغير 4، يعني 3 × 4 = 12.","prompt":"3CH₄: فيهم كام atom من الـ hydrogen؟","options":[{"id":"a","text":"12","correct":true},{"id":"b","text":"7","correct":false},{"id":"c","text":"4","correct":false}],"answer_t_s":239.56,"concept_id":"chem.natural-gas-methane"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.natural-gas-methane"]},{"id":"chem-s3-en.video-walkthrough-phys.electric-current","kind":"walkthrough","version":6,"ord":409,"content_lang":"ar-EG","primary_concept_id":"phys.electric-current","concepts":[{"concept_id":"phys.electric-current","role":"primary"}],"title":"Electric current: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-phys.electric-current v1 (s1 hook: battery, two wires and a bulb, cut one wire; MCQ option a 'it stays lit: the battery still has energy' = s2 myth 1; s2 KeyTerm 'Electric current' verbatim (s2l23), 'The battery pushes the charges. They flow only round a closed path.', 'In a metal wire, the moving charges are the free electrons'; s3 'Each ion is pulled to the plate with the opposite charge' (s2l18 verbatim), 'In a solid salt, they are fixed in place'; s4 TrueFalse 'positive ions move towards the plate joined to the positive terminal' = false (s2 myth 2), MCQ sugar in pure water (self-check, lesson layer: sugar does not form ions in water); s5 subtitle 'Moving charges need a closed path' = takeaway, 'an air gap that the charges cannot cross' (s2l9), Next note 'a current through a solution of metal ions can coat an object with that metal' (s4l3)); concept phys.electric-current v2 (no recorded misconceptions: s2 refutes the lesson's hook and TrueFalse mistakes); prereq phys.electric-charges summary (positive/negative, like repel, unlike attract) taught in s1; dependents: chem.electroplating-basic (title 'Electroplating', in chapter map, in_book=false) and its in-book dependent 'Alloys: definition and preparation' (book p.19 '2. By electro deposition'): both named on chips, no metals/electrodes/equations added. Visual language reused from the concept's short (circuit loop, gap, electron dots in a wire, beaker with + / − plates). Terms (defined at first use): s1 electric charge, positive, negative (3); s2 electric current, battery, closed path, conductor, free electrons, solution, ions, plates. s3 none new; s4 only the dependents' titles (electroplating glossed 'cover something with a thin metal layer', alloys named). Worked example: salt water with two plates, battery and bulb, step by step (closed path → electrons in wires → ions free in the solution → ions to the opposite plates → bulb lights). Self-check NEW case: sugar in pure water -> no current (no ions). Predicts: s2l5 (~1:25), s3l9 (~3:40). not-in-source: a torch contains a battery, wires and a bulb; charges push or pull each other (plain meaning); the hose-of-water picture of a flow; wires are metal and metal lets charges pass; electrons carry negative charge; the metal stays in place while electrons drift (lesson layer says metal ions stay in place: simplified to 'the metal'); salt in water breaks into ions, some positive and some negative; with salt water between the plates the bulb lights; electroplating = covering an object with a thin metal layer. Estimated duration ≈ 279 s (≈ 4:39; 557 words at ~2.4 words/s + 39.2 s pauses + joins); planning aid only.","title":"Electric current: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"The torch switch presses down (2 px shift) on cue 'تدوس'; a cone of light (ctx gradient, C.gold, alpha 0.5) opens from the glass front and YK.glowCircle on the bulb on cue 'فينوّر'.","tts_text":"افتكر الكشاف اللي في البيت: تدوس على الزرار، فينوّر.","screen_text":"Press the switch: light","pause_after_s":0.4},{"id":"s1l3","visual":"Picture change: the torch body becomes see-through (alpha tween 1 → 0.15) from cue 'فتحناه'; inside, the circuit of the lesson / the concept's short: a battery (ctx rounded rect with '+' and '−' ends, C.steel), wires as thick C.textDim strokes, a bulb (ctx circle + filament; lit = C.gold YK.glowCircle) is revealed piece by piece on cues 'بطارية' / 'وأسلاك' / 'ولمبة'; the loop is traced once in gold (YK.bracket-style stroke progress along the wire path) on cue 'متوصلين'. No English labels yet (the words come later).","tts_text":"لو فتحناه، هنلاقي بطارية وأسلاك ولمبة صغيرة، متوصلين ببعض.","screen_text":"Inside the torch","pause_after_s":0.4},{"id":"s1l4","visual":"YK.zoomThrough(ctx, t, {from: drawCircuit, to: drawWireInside, focus: bottom wire, badge: '×10^8'}) from cue 'كبّرنا'; inside: a row of grey discs (YK.atomDisc symbol:false, C.steel, r 40) and small dots between them (YK.particles mode 'float', seed 2, C.textDim) on cue 'حبيبات'. YK.scaleBadge in the stage corner.","tts_text":"لو كبّرنا جوه السِلك جدًا، هنلاقي حبيبات صغيرة أوي.","screen_text":"Zoom in ×10^8","pause_after_s":0.4},{"id":"s1l5","visual":"Two large discs isolated on the stage (x 1100 / 1500, y 580, r 80) get a soft halo (YK.glowCircle) on cue 'charge'; YK.termCard(ctx, 96, 380, {term: 'electric charge', align: 'left', p: on cue 'electric'}); small arrows between the discs flicker toward / away on cues 'تشد' / 'تزق' (no sign yet).","tts_text":"الحبيبات دي شايلة حاجة اسمها electric charge، بتخلّيها تشِدّ أو تزُقّ.","screen_text":"electric charge","pause_after_s":0.4},{"id":"s1l6","visual":"Left disc gets a coral '+' badge (YK.atomDisc charge '+', coral) and tag 'positive' (40) on cue 'positive'; right disc gets a cyan '−' badge and tag 'negative' (40) on cue 'negative'; the term card adds two YK.chip lines 'positive (+)' / 'negative (−)' on the same cues.","tts_text":"والـ charge نوعين: positive زي علامة زائد، و negative زي علامة ناقص.","screen_text":"positive (+) · negative (−)","pause_after_s":0.4},{"id":"s1l7","visual":"The '+' and '−' discs slide toward each other (YK.tween, ease outBack) on cue 'attract', two gold arrows pointing inward; YK.fpara 'positive + negative: attract' (44) in the text panel.","tts_text":"الـ positive والـ negative بيعملوا attract، يعني كل واحد بيشِدّ التاني.","screen_text":"positive + negative: attract","pause_after_s":0.4},{"id":"s1l8","visual":"Picture change: two '+' discs (coral) on the upper half and two '−' discs (cyan) on the lower half, each pair pushes apart (outward arrows) on cue 'repel'; tags 'positive' / 'negative' on their cues; YK.fpara 'positive & positive · negative & negative: repel' (40) in the text panel.","tts_text":"أما two positive، أو two negative، فبيعملوا repel، يعني بيزُقّوا بعض.","screen_text":"positive & positive · negative & negative: repel","pause_after_s":0.4},{"id":"s1l9","visual":"Micro-recap: the s1 cards collapse into three YK.chip kind 'concept' in a row in the text panel (96, 300 / 420 / 540) on cues 'electric', 'positive', 'negative'; the matching discs on the stage pulse in the same order (YK.pulse).","tts_text":"يبقى معانا: electric charge، ونوعينه positive و negative، خلّيهم في بالك.","screen_text":"electric charge · positive · negative","pause_after_s":1},{"id":"s2l2","visual":"Back to the torch circuit (stage, large): a stream of small gold dots (YK.flyer along the wire path, seeded spacing) starts moving round the loop on cue 'تجري' and the bulb lights (YK.glowCircle C.gold) on cue 'current'; YK.tag 'charges' (40) on one dot on cue 'charges'.","tts_text":"لما الـ charges تِجري في السِلك، الجريان ده اسمه electric current كده.","screen_text":"charges flowing in the wire","pause_after_s":0.4},{"id":"s2l3","visual":"YK.termCard(ctx, 96, 380, {term: 'Electric current', align: 'left', p: on cue 'electric'}) + YK.fpara 'a flow of electric charges' (44, 'flow' gold) on cue 'ماشية'; inset YK.panel(ctx, 1460, 200, 340, 220): a hose (ctx stroke) with water dots (C.cyan) flowing on cue 'مية'.","tts_text":"يعني الـ electric current هو charges ماشية ورا بعض، زي مَيّة في خرطوم.","screen_text":"Electric current: a flow of electric charges","pause_after_s":0.6},{"id":"s2l4","visual":"Inset out; the battery glows (YK.pulse) and a gold push chevron appears at its '+' end on cue 'بيزق'; YK.tag 'battery' (44) on it on cue 'battery'; YK.termCard(ctx, 96, 380, {term: 'battery', align: 'left'}) + YK.fpara 'pushes the charges' (40) (lesson s2 wording).","tts_text":"واللي بيزُقّ الـ charges دي هي الـ battery، البطارية اللي في الكشاف.","screen_text":"battery: pushes the charges","pause_after_s":0.4},{"id":"s2l5","visual":"Lesson hook: the top wire opens with a small gap (two wire ends pull apart 40 px) on cue 'قطعنا' — dots freeze in place, bulb state held as it was (still lit) so nothing is answered. YK.predictCard(ctx, t, {at: YK.cue('s2l5'), until: YK.cue('s2l6') + 0.4, think: YK.cueEnd('s2l5'), end: YK.cue('s2l6'), kind: 'PREDICT', q: 'Cut one wire. What happens to the bulb?'}); think ring through the 3 s silence.","tts_text":"طب لو قطعنا سِلك واحد، اللمبة هتفضل منوّرة ولا هتِطفي؟ فكّر.","screen_text":"PREDICT: cut one wire. The bulb?","pause_after_s":3},{"id":"s2l6","visual":"Answer: bulb glow fades to 0 on cue 'بتطفي'; the dots stop; the battery keeps a full charge icon (ctx bar, mint) on cue 'battery'; YK.answerSlot(ctx, t, {at: YK.cueX('s2l6','بتطفي'), text: 'It goes out', x: 420, y: 760}).","tts_text":"اللمبة بتِطفي، مع إن الـ battery لسه فيها energy كتير.","screen_text":"It goes out ✓ (the battery still has energy)","pause_after_s":0.6},{"id":"s2l7","visual":"Misconception (lesson hook option a 'it stays lit: the battery still has energy'; no misconception recorded for this concept): YK.mythLine(ctx, t, {at: YK.cue('s2l7'), wrongAt: YK.cueX('s2l7','غلط'), until: YK.cueEnd('s2l9') + 1.5, text: 'The battery is enough', x: 96, y: 300, size: 48}) — coral with ✕ (YK.wrongMark) from the «غلط» cue for its whole visible time; no strike-through.","tts_text":"فيه ناس فاكرة إن الـ battery لوحدها كفاية تنوّر اللمبة، وده غلط.","screen_text":"The battery is enough ✕","pause_after_s":0.4},{"id":"s2l8","visual":"Fix (held ≥ the myth): the gap closes again on cue 'مقفول'; the whole loop is traced gold end to end (stroke progress) on cue 'path', dots flow again and the bulb relights; YK.fpara 'closed path: no gap' (44, mint, 96, 420) + YK.rightMark on cue 'قطع'. Myth line + ✕ stay above.","tts_text":"الـ charges محتاجة closed path، يعني طريق مقفول من غير قطع.","screen_text":"closed path: no gap ✓","pause_after_s":0.4},{"id":"s2l9","visual":"Close-up inset (YK.panel 1180, 200, 600, 360): the cut opens again; dots pile up at the wire end and bounce back from the gap (short back-and-forth, never crossing) on cue 'بتعدّي'; tag 'air gap' (36) in the gap on cue 'هوا'; the bulb in the main view dims on cue 'بيقف'. Lesson s5: 'an air gap that the charges cannot cross'.","tts_text":"عند القطع فيه هوا، والـ charges مش بتعدّي الفتحة دي، فالـ current بيقف.","screen_text":"Air gap: charges cannot cross → current stops","pause_after_s":0.6},{"id":"s2l10","visual":"Gap closed; the wire glows steel-blue (YK.glow) on cue 'السلك'; YK.termCard(ctx, 96, 380, {term: 'conductor', align: 'left'}) on cue 'conductor' + YK.fpara 'lets charges flow (e.g. a wire)' (40, textDim).","tts_text":"السِلك معدن، والمعدن بيسيب الـ charges تعدّي، فاسمه conductor كده.","screen_text":"conductor: lets charges flow (e.g. a wire)","pause_after_s":0.4},{"id":"s2l11","visual":"Picture change: YK.camera push into the wire: a row of grey metal discs (YK.atomDisc symbol:false, C.steel, r 40) with small cyan dots carrying '−' (YK.atomDisc r 12, charge '−') drifting between them on cue 'بيتحرك'; YK.tag 'free electrons' (44) on cue 'free'; a '−' badge flashes on the dots on cue 'negative'. Same drawing as the concept's short.","tts_text":"وجوه السِلك، اللي بيتحرك اسمه free electrons، ونوعهم negative كمان.","screen_text":"In a wire: free electrons move","pause_after_s":0.4},{"id":"s2l12","visual":"The cyan dots keep drifting left → right on cue 'بتجري'; the grey metal discs do not move (a thin outline 'pin' ring pulses on them) on cue 'ثابت'; YK.fpara 'the electrons drift; the metal stays in place' (40).","tts_text":"الـ electrons دي بتِجري بين حبيبات الـ metal، والـ metal نفسه ثابت مكانه.","screen_text":"the electrons drift; the metal stays in place","pause_after_s":0.4},{"id":"s2l13","visual":"Picture change: YK.beaker(ctx, 1307, 640, 520, 560, {level: 0.7, color: 'rgba(200,210,230,0.25)'}); a spoon of white salt grains (ctx dots) pours in and the grains vanish into the water (alpha → 0) on cue 'دوّبنا'; YK.termCard(ctx, 96, 380, {term: 'solution', align: 'left'}) on cue 'solution' + YK.fpara 'e.g. salt dissolved in water' (40, textDim).","tts_text":"ولو دوّبنا ملح في مَيّة، يبقى عندنا solution، يعني محلول ملح.","screen_text":"solution: e.g. salt dissolved in water","pause_after_s":0.4},{"id":"s2l14","visual":"Zoom into the beaker (YK.zoomThrough, badge '×10^8'): free particles drifting in the water (YK.atomDisc r 26, symbol:false, seeded positions, slow wander with t) on cue 'بيتفك'; they get small charge badges on cue 'charge'; YK.termCard(ctx, 96, 380, {term: 'ions', align: 'left'}) on cue 'ions' + YK.fpara 'charged particles' (40, textDim).","tts_text":"الملح ده جوه المية بيتفك لحبيبات شايلة charge، اسمها ions كده.","screen_text":"ions: charged particles","pause_after_s":0.4},{"id":"s2l15","visual":"Half the particles turn coral with '+' badges on cue 'positive', the other half cyan with '−' badges on cue 'negative' (YK.atomDisc charge); tags 'positive ions' / 'negative ions' (36) on one of each.","tts_text":"فيه ions نوعها positive، وفيه ions نوعها negative، في نفس المحلول.","screen_text":"positive ions · negative ions","pause_after_s":0.4},{"id":"s2l16","visual":"Zoom back out: two plates (ctx roundRect 40 × 360) dip into the beaker (x 1120 / 1500) on cue 'plates'; wires run up to a battery above (y 230) on cue 'battery'; tag 'plates' (40) on cue 'plates', 'battery' (36) on the battery.","tts_text":"نحط في المحلول plates، يعني ألواح، متوصلة مع الـ battery كده.","screen_text":"plates joined to the battery","pause_after_s":0.4},{"id":"s2l17","visual":"The left plate (joined to the '+' end) tints coral with a '+' badge on cue 'positive'; the right plate (joined to '−') tints cyan with a '−' badge on cue 'negative'; the two wire ends glow on cue 'طرف'. Lesson diagram labels 'joined to +' / 'joined to −' as small tags (32) on the wires.","tts_text":"الـ plate ده بقى positive، والتاني negative، حسب طرف الـ battery كده.","screen_text":"one plate positive, the other negative","pause_after_s":0.4},{"id":"s2l18","visual":"Lesson s3 wording in the text panel (YK.fpara 44, 'opposite' gold). Stage: the ions start drifting toward the plates (YK.flyer short arcs, staggered) on cue 'بتتشد'; a gold arrow (no label) flashes between one '+' ion and the '−' plate on cue 'عكسها'.","tts_text":"الـ ions بتتشِدّ ناحية الـ plate اللي الـ charge بتاعه عكسها.","screen_text":"Each ion is pulled to the plate with the opposite charge.","pause_after_s":0.4},{"id":"s2l19","visual":"Coral '+' ions gather at the cyan '−' plate on cue 'positive'#1…'negative'; cyan '−' ions gather at the coral '+' plate on cue 'والعكس'; two flow arrows (YK.flow edges, curve 0.15) labelled 'positive ions' / 'negative ions' (32).","tts_text":"يعني الـ ions الـ positive بتروح للوح الـ negative، والعكس كمان.","screen_text":"positive ions → negative · negative ions → positive","pause_after_s":0.4},{"id":"s2l20","visual":"Misconception (lesson TrueFalse: 'positive ions move towards the plate joined to the positive terminal' = false): YK.mythLine(ctx, t, {at: YK.cue('s2l20'), wrongAt: YK.cueX('s2l20','غلط'), until: YK.cueEnd('s2l21') + 1.5, text: 'positive ions → positive plate', x: 96, y: 300, size: 44}) with ✕ for its whole visible time; a ghost coral ion drifting to the coral plate is crossed by YK.wrongMark on the same cue.","tts_text":"ناس فاكرة إن الـ positive ions بتروح ناحية الـ plate الـ positive: غلط.","screen_text":"positive ions → positive plate ✕","pause_after_s":0.4},{"id":"s2l21","visual":"Fix (held ≥ the myth): the ghost ion is pushed back from the coral plate (outward arrows, as in s1l8) on cue 'بيتنافروا' and joins the others at the cyan plate; YK.fpara 'positive ions move away from the positive plate' (40, mint) + YK.rightMark on cue 'خالص'. Myth line + ✕ stay above.","tts_text":"الشبيهين بيتنافروا: الـ positive ions بتبعد عن الـ plate الـ positive خالص.","screen_text":"positive ions move away from the positive plate ✓","pause_after_s":0.6},{"id":"s2l22","visual":"Picture change: a salt crystal (YK.lattice(ctx, 1100, 420, 420, 320, {rows: 4, cols: 5, pack: 'square'}) with alternating coral '+' / cyan '−' discs) between the two plates; the ions jiggle in place only (tiny seeded wobble) on cue 'ثابتة'; the bulb icon above stays dark; YK.fpara 'Solid salt: ions fixed in place → no current' (40). Lesson s3 muted line.","tts_text":"إنما في الملح الناشف، الـ ions ثابتة مكانها، فمفيش current بيعدّي.","screen_text":"Solid salt: ions fixed in place → no current","pause_after_s":0.6},{"id":"s2l23","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 360, {term: 'Electric current', def: 'A flow of electric charges through a conductor or a solution.', keys: ['flow', 'conductor', 'solution'], align: 'left', p: on cue 'electric'}); stage split: the wire close-up (electrons drifting) left on cue 'conductor', the beaker (ions moving) right on cue 'solution'.","tts_text":"يبقى الـ electric current هو charges بتسري في conductor، أو في solution كده.","screen_text":"Electric current: A flow of electric charges through a conductor or a solution.","pause_after_s":1},{"id":"s3l2","visual":"Stage: the lesson's setup built on cues: battery (top) on 'battery', bulb in the top wire on 'ولمبة', wires on 'وأسلاك', two plates in a YK.beaker of salt water on 'plates'; tag 'salt water' would be unspoken English: none. Steps will stack in the text panel (YK.list, LTR, 96, 300).","tts_text":"المثال: battery ولمبة وأسلاك، و two plates جوه محلول ملح.","screen_text":"Example: battery + 2 plates","pause_after_s":0.4},{"id":"s3l3","visual":"YK.fpara 'Will the bulb light?' (48, gold) at the top of the text panel on cue 'السؤال'; the bulb outline pulses once (YK.pulse) on cue 'اللمبة'.","tts_text":"السؤال: اللمبة هتنوّر ولا لأ؟ نمشي خطوة خطوة.","screen_text":"Will the bulb light?","pause_after_s":0.4},{"id":"s3l4","visual":"Step 1: the loop is traced gold from the battery's '+' end, through the wire, plate, the water between the plates, the other plate, the bulb, back to '−' (stroke progress) from cue 'path' to cue 'تاني'; YK.list item 'closed path' + YK.rightMark small on cue 'تاني'.","tts_text":"أولًا: فيه closed path، من الـ battery ولحد ما يرجعلها تاني.","screen_text":"closed path ✓","pause_after_s":0.4},{"id":"s3l5","visual":"Step 2: small cyan '−' dots drift along both wires (as in s2l11) on cue 'electrons'; YK.list item 'wires: free electrons move' on cue 'free'.","tts_text":"تانيًا: في الأسلاك، الـ free electrons هي اللي بتتحرك.","screen_text":"In the wires: free electrons move","pause_after_s":0.4},{"id":"s3l6","visual":"Step 3: zoom inset on the water between the plates: coral '+' and cyan '−' ions wandering freely on cue 'حرة'; YK.list item 'solution: ions free to move' on cue 'ions'.","tts_text":"تالتًا: في الـ solution، الـ ions حرة تتحرك، مش ثابتة.","screen_text":"In the solution: ions are free to move","pause_after_s":0.4},{"id":"s3l7","visual":"Step 4: in the inset coral '+' ions drift to the cyan '−' plate on cue 'positive'#1, cyan '−' ions to the coral '+' plate on cue 'negative'#2; YK.list item 'positive ions → negative · negative ions → positive'.","tts_text":"الـ positive ions تروح للوح الـ negative، والـ negative ions للوح الـ positive كده.","screen_text":"positive ions → negative · negative ions → positive","pause_after_s":0.4},{"id":"s3l8","visual":"Result: dots flow in the wires and ions keep drifting at the same time; the bulb lights (YK.glowCircle C.gold) on cue 'بتنوّر'; YK.answerSlot(ctx, t, {at: YK.cueX('s3l8','current'), text: 'Current flows: the bulb lights', x: 420, y: 900}).","tts_text":"يبقى الـ current بيعدّي في الدايرة كلها، واللمبة بتنوّر.","screen_text":"Current flows: the bulb lights ✓","pause_after_s":0.6},{"id":"s3l9","visual":"Self-check on a NEW case (the example was salt water; lesson MCQ option c): the beaker's water empties and refills clear; a sugar cube (ctx white rounded square) dissolves in it on cue 'سكر'. YK.predictCard(ctx, t, {at: YK.cue('s3l9'), until: YK.cue('s3l10') + 0.4, think: YK.cueEnd('s3l9'), end: YK.cue('s3l10'), kind: 'QUICK CHECK', q: 'Sugar dissolved in pure water: will a current flow?'}); YK.checkPause(ctx, 1307, 860, {t, start: YK.cueEnd('s3l9'), dur: 4}); only the question shows during the pause (bulb drawn unlit-neutral grey, no hint).","tts_text":"دورك: سكر متدوّب في مَيّة نقية، هيعدّي current ولا لأ؟ وقّف وفكّر.","screen_text":"Your turn: sugar in pure water. Current?","pause_after_s":4},{"id":"s3l10","visual":"Answer: the bulb stays dark, no dots move on cue 'الإجابة'; YK.answerSlot(ctx, t, {at: YK.cueX('s3l10','الإجابة'), text: 'No current: the bulb stays dark', x: 420, y: 700}).","tts_text":"الإجابة: لأ، مفيش current، واللمبة مش هتنوّر خالص.","screen_text":"No current: the bulb stays dark ✓","pause_after_s":0.4},{"id":"s3l11","visual":"Reason: zoom inset into the water: neutral grey sugar particles (YK.atomDisc r 26, symbol:false, no badges) wandering, no charge badges at all, on cue 'ions'; YK.fpara 'Sugar forms no ions: no moving charges' (44, mint) on cue 'السبب' (lesson layer: sugar does not form ions in water).","tts_text":"السبب: السكر مش بيعمل ions في المية، فمفيش charges تتحرك.","screen_text":"Sugar forms no ions: no moving charges","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, 'Electroplating', {kind: 'concept', align: 'left'}) (map title_en exactly) on cue 'electroplating'; a plain grey key shape (ctx path) gets a thin shiny coat sweeping over it (gradient sweep, C.steel → lighter) on cue 'بطبقة'.","tts_text":"في الفصل هتقابل الـ electroplating، يعني نغطي حاجة بطبَقة معدن رقيقة.","screen_text":"Electroplating","pause_after_s":0.4},{"id":"s4l3","visual":"Mini setup (same plates + beaker drawing as s2l16, small, x 1300 y 640): the key hangs as one plate; ion dots drift to it on cue 'ions' and a thin layer builds on it on cue 'يغطي'; YK.fpara 'current + a solution of ions → a thin coat' (40). Lesson s5 'Next' note; no electrode names, no metal names (the chapter teaches them).","tts_text":"بنعدّي current في solution فيه ions معدن، فالمعدن يغطي الجسم.","screen_text":"current + a solution of ions → a thin coat","pause_after_s":0.4},{"id":"s4l4","visual":"Second YK.chip(ctx, 820, 560, 'Alloys: definition and preparation', {kind: 'concept', align: 'left'}) on cue 'alloys' (map title_en exactly; book p.19 '2. By electro deposition'); a dashed link from the Electroplating chip to it on cue 'الفكرة'. No metals named, no equation.","tts_text":"وفي درس الـ alloys، يعني معدن متخلّط بحاجة تانية، هتشوف نفس الفكرة دي.","screen_text":"Alloys: definition and preparation","pause_after_s":0.6},{"id":"s4l5","visual":"Both chips get small gold link tags 'moving ions' and 'closed path' (36) on cues 'ions' / 'path'; the mini setup's loop traces gold once on 'path'.","tts_text":"والاتنين محتاجين اللي اتعلمناه: ions بتتحرك، و closed path من غير قطع.","screen_text":"They need: moving ions + a closed path","pause_after_s":0.6},{"id":"s4l6","visual":"Recap (s4l6–s4l7 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l6'), until: YK.cue('s4l8'), title: 'Electric current', line: 'A flow of electric charges · source: a battery', pulse: [{word: 'charges', at: YK.cueX('s4l6','charges')}, {word: 'battery', at: YK.cueX('s4l6','battery')}]}); stage: the torch circuit returns small with dots flowing.","tts_text":"الخلاصة: الـ electric current هو charges بتتحرك، ومحتاج مصدر زي الـ battery كده.","screen_text":"Electric current: a flow of electric charges · source: a battery","pause_after_s":0.4},{"id":"s4l7","visual":"Same recap card, second line 'wire: free electrons · solution: ions · a closed path' added on cue 'electrons'; the stage loop traces gold on cue 'path'.","tts_text":"في السِلك free electrons، وفي الـ solution ions، وكله في closed path مقفول.","screen_text":"wire: free electrons · solution: ions · a closed path","pause_after_s":0.6},{"id":"s4l8","visual":"Voiced lock-in = takeaway (lesson subtitle): YK.takeaway(ctx, {title: 'Electric current', line: 'Moving charges need a closed path.', t, pulse: [{word: 'charges', at: YK.cueX('s4l8','charges')}, {word: 'closed', at: YK.cueX('s4l8','closed')}, {word: 'path', at: YK.cueX('s4l8','path')}]}) held ≥ 2.5 s; no fade to black, no outro.","tts_text":"يعني الـ charges اللي بتتحرك محتاجة closed path كده.","screen_text":"Moving charges need a closed path.","pause_after_s":1.5}],"logline":"هتعرف إن الـ electric current هو charges بتتحرك، وإنه محتاج battery و closed path، وإيه اللي بيتحرك في السلك وفي الـ solution.","segments":[{"id":"s1","title":"What lights a torch","concept_id":"phys.electric-current"},{"id":"s2","title":"Charges on the move: wires and solutions","concept_id":"phys.electric-current"},{"id":"s3","title":"Will the bulb light?","concept_id":"phys.electric-current"},{"id":"s4","title":"Where Chapter 1 uses electric 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الكشاف اللي في البيت تدوس على الزرار\nفينوّر\nلو فتحناه هنلاقي بطارية وأسلاك ولمبة صغيرة\nمتوصلين ببعض\nلو كبّرنا جوه السِلك جدًا هنلاقي حبيبات\nصغيرة أوي\nالحبيبات دي شايلة حاجة اسمها electric\ncharge بتخلّيها تشِد أو تزُق\nوالـ charge نوعين positive زي علامة زائد و\nnegative زي علامة ناقص\nالـ positive والـ negative بيعملوا attract\nيعني كل واحد بيشِد التاني\nأما two positive أو two negative فبيعملوا\nrepel يعني بيزُقّوا بعض\nيبقى معانا electric charge ونوعينه\npositive و negative خلّيهم في بالك\nلما الـ charges تِجري في السِلك الجريان ده\nاسمه electric current كده\nيعني الـ electric current هو charges ماشية\nورا بعض زي مَيّة في خرطوم\nواللي بيزُق الـ charges دي هي الـ battery\nالبطارية اللي في الكشاف\nطب لو قطعنا سِلك واحد اللمبة هتفضل منوّرة\nولا هتِطفي فكّر\nاللمبة بتِطفي مع إن الـ battery لسه فيها\nenergy كتير\nفيه ناس فاكرة إن الـ battery لوحدها كفاية\nتنوّر اللمبة وده غلط\nالـ charges محتاجة closed path يعني طريق\nمقفول من غير قطع\nعند القطع فيه هوا والـ charges مش بتعدّي\nالفتحة دي فالـ current بيقف\nالسِلك معدن والمعدن بيسيب الـ charges\nتعدّي فاسمه conductor كده\nوجوه السِلك اللي بيتحرك اسمه free\nelectrons ونوعهم negative كمان\nالـ electrons دي بتِجري بين حبيبات الـ\nmetal والـ metal نفسه ثابت مكانه\nولو دوّبنا ملح في مَيّة يبقى عندنا\nsolution يعني محلول ملح\nالملح ده جوه المية بيتفك لحبيبات شايلة\ncharge اسمها ions كده\nفيه ions نوعها positive وفيه ions نوعها\nnegative في نفس المحلول\nنحط في المحلول plates يعني ألواح متوصلة مع\nالـ battery كده\nالـ plate ده بقى positive والتاني negative\nحسب طرف الـ battery كده\nالـ ions بتتشِد ناحية الـ plate اللي الـ\ncharge بتاعه عكسها\nيعني الـ ions الـ positive بتروح للوح الـ\nnegative والعكس كمان\nناس فاكرة إن الـ positive ions بتروح ناحية\nالـ plate الـ positive غلط\nالشبيهين بيتنافروا الـ positive ions بتبعد\nعن الـ plate الـ positive خالص\nإنما في الملح الناشف الـ ions ثابتة مكانها\nفمفيش current بيعدّي\nيبقى الـ electric current هو charges بتسري\nفي conductor أو في solution كده\nالمثال battery ولمبة وأسلاك و two plates\nجوه محلول ملح\nالسؤال اللمبة هتنوّر ولا لأ نمشي خطوة خطوة\nأولًا فيه closed path من الـ battery ولحد\nما يرجعلها تاني\nتانيًا في الأسلاك الـ free electrons هي\nاللي بتتحرك\nتالتًا في الـ solution الـ ions حرة تتحرك\nمش ثابتة\nالـ positive ions تروح للوح الـ negative\nوالـ negative ions للوح الـ positive كده\nيبقى الـ current بيعدّي في الدايرة كلها\nواللمبة بتنوّر\nدورك سكر متدوّب في مَيّة نقية هيعدّي\ncurrent ولا لأ وقّف وفكّر\nالإجابة لأ مفيش current واللمبة مش هتنوّر\nخالص\nالسبب السكر مش بيعمل ions في المية فمفيش\ncharges تتحرك\nطب الكلام ده هيفيدك فين في الفصل\nفي الفصل هتقابل الـ electroplating يعني\nنغطي حاجة بطبَقة معدن رقيقة\nبنعدّي current في solution فيه ions معدن\nفالمعدن يغطي الجسم\nوفي درس الـ alloys يعني معدن متخلّط بحاجة\nتانية هتشوف نفس الفكرة دي\nوالاتنين محتاجين اللي اتعلمناه ions بتتحرك\nو closed path من غير قطع\nالخلاصة الـ electric current هو charges\nبتتحرك ومحتاج مصدر زي الـ battery كده\nفي السِلك free electrons وفي الـ solution\nions وكله في closed path مقفول\nيعني الـ charges اللي بتتحرك محتاجة closed\npath كده","countable":false,"session_id":"chem-s3-en.ch1.s7","session_no":7,"session_ord":33,"see_also":[{"item_id":"chem-s3-en.lesson-alloy.definition-preparation","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Alloys: definition and preparation","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":69.31,"kind":"pause_question","spec":{"answer":"هتطفي: الـ charges محتاجة closed path من غير gap.","prompt":"لو قطعنا سلك واحد: اللمبة هتفضل منوّرة ولا هتطفي؟","options":[{"id":"a","text":"هتطفي","correct":true},{"id":"b","text":"هتفضل منوّرة، عشان الـ battery لسه فيها energy","correct":false}],"answer_t_s":72.95,"concept_id":"phys.electric-current"},"content_lang":"ar-EG"},{"id":"think-2","t_s":214.5,"kind":"pause_question","spec":{"answer":"لأ: السكر مش بيعمل ions في المية، فمفيش charges تتحرك.","prompt":"سكر متدوّب في مية نقية: هيعدّي current؟","options":[{"id":"a","text":"لأ","correct":true},{"id":"b","text":"أيوه، زي محلول الملح","correct":false}],"answer_t_s":218.53,"concept_id":"phys.electric-current"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-phys.electric-current"]},{"id":"chem-s3-en.video-walkthrough-chem.solution-concentration","kind":"walkthrough","version":6,"ord":451,"content_lang":"ar-EG","primary_concept_id":"chem.solution-concentration","concepts":[{"concept_id":"chem.solution-concentration","role":"primary"}],"title":"Concentrated and dilute solutions: from zero","payload":{"notes":"Sources: lesson chem-s3-en.lesson-chem.solution-concentration v1 (s1 hook: the same H2SO4 labelled dilute / concentrated in Ch.1, MCQ options a 'two different compounds' and c 'fewer H atoms in its formula' = s2 myth 2 and s2l21; s2 KeyTerm 'Concentrated solution' verbatim + 'a dissolved substance, the solute, spread through a solvent such as water'; s3 KeyTerm 'Dilute solution' verbatim + interactive 'the same 8 solute particles' 100→400 mL, Stat per 100 mL = 800/v (s2l10-11); s4 MCQ A 5 g/50 mL vs B 10 g/500 mL with wrong option 'B, because it holds more sugar' (= s2 myth 1; worked example s3 with the lesson's own division 0.1 vs 0.02 g in each mL) and TrueFalse 'different compounds' = false; s5 recap 'Adding water dilutes a solution. The solute itself does not change.' (s2l12 verbatim) and Next note 'iron gives different products with dilute and with hot concentrated sulphuric acid' (s4l5, no products named)); concept chem.solution-concentration v2 (no recorded misconceptions: s2 refutes the lesson's check mistakes); dependents named on chips with map titles: 'Iron with dilute acids' and 'Iron with hot concentrated sulphuric acid' (book p.21: (dil) / (conc.) labels on the arrows; fe.reaction-conc-sulfuric.mc1 'concentrated gives H2 like dilute' respected: no products or gases shown in s4). Visual language reused from the concept's short (glasses with dense / sparse dots, add-water pour, myth pill). Terms (defined at first use): s1 solution, solute, solvent (3); s2 volume (mL), concentrated solution, dilute solution, acid, sulphuric acid, formula, compounds (glossed 'two different substances'). s3 none new; s4 only the dependents' titles ('hot' voiced as «السخن», iron glossed «الحديد»). Units voiced: g = «جرام», mL = «مللي»; decimals digit by digit («صفر فاصل صفر اتنين»). Self-check NEW case (not in the lesson): 6 g in 200 mL vs 3 g in 50 mL -> 3 g in 50 mL (0.06 vs 0.03 g in each mL). Predicts: s2l3 (~1:05), s3l10-11 (~3:45). not-in-source: sugar stirred into water seems to vanish but the water tastes sweet; zoomed in, sugar particles are spread among water particles; 5 spoons in the same glass is sweeter / more concentrated than 1; volume = the space the solution takes, measured in mL; acid is what makes lemon sour; sulphuric acid is a common lab acid; formula = the short written name; 6 g in 200 mL = 0.03 g/mL, 3 g in 50 mL = 0.06 g/mL. Estimated duration ≈ 279 s (≈ 4:39; 555 words at ~2.4 words/s + 39.8 s pauses + joins); planning aid only.","title":"Concentrated and dilute solutions: from zero","voice":{"model":"gemini-3.8-flash-tts","voice":"ar-eg-training-5","provider":"gemini","language_code":"ar-EG"},"aspect":"16:9","format":"walkthrough","script":[{"id":"s1l2","visual":"The spoon tips and the grains fall into the water on cue 'معلقة'; a spoon handle stirs in a circle (rotation tween) and the liquid swirls (seeded ripple lines) on cue 'وقلبناها'.","tts_text":"تخيّل كوباية مَيّة، وحطّينا فيها معلقة سكر وقلّبناها كويس.","screen_text":"A glass of water + a spoon of sugar","pause_after_s":0.4},{"id":"s1l3","visual":"The grains fade out while the stirring settles (alpha 1 → 0) on cue 'بيختفي'; a small gold sparkle (YK.particles mode 'float', C.gold, alpha 0.3) lingers in the liquid on cue 'مسكّر' to say 'still there'.","tts_text":"السكر بيختفي من قدام عينك، إنما طعم المية بقى مسكّر.","screen_text":"The sugar seems to vanish","pause_after_s":0.4},{"id":"s1l4","visual":"YK.zoomThrough(ctx, t, {from: drawGlass, to: drawParticles, focus: glass centre, badge: '×10^8'}) from cue 'كبّرنا': many small pale-blue dots (water, C.cyan alpha 0.35, seeded wander) with a few larger gold dots (sugar, C.gold) spread among them on cue 'متفرقة'. YK.scaleBadge in the stage corner. Same particle picture as the lesson diagram (solute dots in a volume).","tts_text":"لو كبّرنا جدًا، هنلاقي حبيبات السكر متفرقة وسط حبيبات المية.","screen_text":"Zoom in ×10^8","pause_after_s":0.4},{"id":"s1l5","visual":"A gold YK.bracket outlines the whole particle field on cue 'الخليط'; YK.termCard(ctx, 96, 380, {term: 'solution', align: 'left', p: on cue 'solution'}) + YK.fpara 'sugar spread through water' (40, textDim).","tts_text":"الخليط ده اللي السكر دايب فيه في المية، اسمه solution كده.","screen_text":"solution: sugar spread through water","pause_after_s":0.4},{"id":"s1l6","visual":"The gold sugar dots pulse (YK.pulse) on cue 'السكر'; YK.tag 'solute' (44, gold) on one gold dot on cue 'solute'; YK.termCard(ctx, 96, 380, {term: 'solute', align: 'left'}) + YK.fpara 'what dissolves (here sugar)' (40).","tts_text":"والحاجة اللي دابت، هنا السكر، اسمها solute كده.","screen_text":"solute: what dissolves (here sugar)","pause_after_s":0.4},{"id":"s1l7","visual":"The pale-blue water dots pulse on cue 'فيها'; YK.tag 'solvent' (44, cyan) on one blue dot on cue 'solvent'; YK.termCard(ctx, 96, 380, {term: 'solvent', align: 'left'}) + YK.fpara 'what it dissolves in, e.g. water' (40) ('e.g.' keeps it from reading as 'always water').","tts_text":"والحاجة اللي دابت فيها اسمها solvent، زي المية هنا مثلًا.","screen_text":"solvent: what it dissolves in, e.g. water","pause_after_s":0.4},{"id":"s1l8","visual":"Micro-recap: the three cards collapse into one line in the text panel: YK.fpara 'solution: a solute dissolved in a solvent' (48) with 'solute' gold and 'solvent' cyan, the words lighting on cues 'solution' / 'solute' / 'solvent'; the particle field shows the matching dots lighting in the same order.","tts_text":"يعني الـ solution هو solute دايب في solvent، زي السكر في المية.","screen_text":"solution: a solute dissolved in a solvent","pause_after_s":1},{"id":"s2l2","visual":"Picture change: two identical glasses (YK.beaker at x 1100 and 1520, y 680, 300 × 400, level 0.6, same colour) on cue 'كوبايتين'; one spoon tips into the left glass on cue 'معلقة', five spoons (staggered) into the right on cue 'معالق'; tags '1 spoon' / '5 spoons' (36) under the glasses.","tts_text":"دلوقتي كوبايتين قدّ بعض: واحدة فيها معلقة، والتانية خمس معالق.","screen_text":"2 equal glasses: 1 spoon · 5 spoons","pause_after_s":0.4},{"id":"s2l3","visual":"YK.predictCard(ctx, t, {at: YK.cue('s2l3'), until: YK.cue('s2l4') + 0.4, think: YK.cueEnd('s2l3'), end: YK.cue('s2l4'), kind: 'PREDICT', q: 'Which glass is sweeter?'}); both glasses stay identical-looking (sugar invisible); think ring through the 3 s silence.","tts_text":"أنهي كوباية هتبقى أحلى في الطعم؟ فكّر قبل ما أقولك.","screen_text":"PREDICT: which glass is sweeter?","pause_after_s":3},{"id":"s2l4","visual":"Answer: both glasses open into particle insets (YK.panel circles over each glass): left few gold dots, right many gold dots among the same blue water dots on cue 'خمس'; YK.answerSlot(ctx, t, {at: YK.cueX('s2l4','خمس'), text: '5 spoons: sweeter', x: 420, y: 760}); an equal-height dashed bracket on both glasses on cue 'الكمية'.","tts_text":"اللي فيها خمس معالق، عشان فيها سكر أكتر في نفس الكمية.","screen_text":"5 spoons: sweeter ✓ (more sugar, same amount of water)","pause_after_s":0.4},{"id":"s2l5","visual":"The dashed brackets on both glasses turn gold and get a ruler tick scale (ctx lines) on cue 'المكان'; YK.termCard(ctx, 96, 380, {term: 'volume', align: 'left', p: on cue 'volume'}) + YK.fpara 'the space it takes (mL)' (40, textDim); 'mL' lights on cue 'بالمللي'.","tts_text":"الكمية دي، يعني المكان اللي المحلول واخده، اسمها volume، وبنقيسها بالمللي.","screen_text":"volume: the space it takes (mL)","pause_after_s":0.4},{"id":"s2l6","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 360, {term: 'Concentrated solution', def: 'A solution with a large amount of solute in a given volume.', keys: ['large amount', 'given volume'], align: 'left', p: on cue 'concentrated'}); the right glass's inset (many dots) glows (YK.glow, C.gold) on cue 'كتير'; tag 'concentrated' (36) on it.","tts_text":"المحلول اللي فيه solute كتير في volume معين، اسمه concentrated solution كده.","screen_text":"Concentrated solution: A solution with a large amount of solute in a given volume.","pause_after_s":0.8},{"id":"s2l7","visual":"Definition card (lesson KeyTerm wording): YK.termCard(ctx, 96, 360, {term: 'Dilute solution', def: 'A solution with a small amount of solute in a given volume.', keys: ['small amount', 'given volume'], align: 'left', accent: C.cyan, p: on cue 'dilute'}); the left glass's inset (few dots) glows cyan on cue 'قليل'; tag 'dilute' (36) on it.","tts_text":"واللي فيه solute قليل في نفس الـ volume، اسمه dilute solution كده.","screen_text":"Dilute solution: A solution with a small amount of solute in a given volume.","pause_after_s":0.8},{"id":"s2l8","visual":"Tags under the glasses update: '5 spoons: concentrated' (right, gold) on cue 'concentrated', '1 spoon: dilute' (left, cyan) on cue 'dilute'; a small double arrow between the glasses (comparison) on cue 'مقارنةً'.","tts_text":"يعني أم خمس معالق concentrated، وأم معلقة واحدة dilute، مقارنةً ببعض.","screen_text":"5 spoons: concentrated · 1 spoon: dilute","pause_after_s":0.4},{"id":"s2l9","visual":"Picture change: the right glass alone, centre-stage, swaps for a taller jug (YK.beaker 300 × 620); water pours in from a jug above (YK.flyer droplets C.cyan) and the level rises on cue 'زوّدنا'; YK.fpara 'Add water: same solute' (44) in the text panel; the gold dot count tag stays the same on cue 'نفسه'.","tts_text":"طب لو زوّدنا مَيّة على الكوباية التقيلة، الـ solute نفسه مش هيزيد.","screen_text":"Add water: same solute","pause_after_s":0.4},{"id":"s2l10","visual":"The lesson's interactive diagram as a sequence: a particle box with exactly 8 gold solute dots in a '100 mL' box (YK.panel, label '100 mL' 36) on cue 'eight'; the box widens to 200, 300, 400 mL (label updates, YK.tween) from cue 'المية' to cue 'millilitres', the 8 dots spreading apart; tag 'the same 8 particles' (32) stays.","tts_text":"نفس الـ eight حبيبات، إنما المية بقت four hundred millilitres بدل one hundred بس.","screen_text":"same 8 particles · 100 mL → 400 mL","pause_after_s":0.4},{"id":"s2l11","visual":"The 400 mL box is split by 3 dashed lines into four 100 mL windows; one window highlights (YK.bracket gold) showing 2 dots on cue 'two'; a ghost of the first 100 mL box with 8 dots beside it on cue 'eight'; YK.fpara 'Each 100 mL: 8 → 2 particles' (44) + tag 'more dilute' (cyan) on cue 'dilute' (lesson Stat: 800 / v per 100 mL).","tts_text":"فكل one hundred millilitres بقى فيها two حبيبات بس بدل eight، يعني dilute أكتر.","screen_text":"Each 100 mL: 8 → 2 particles · more dilute","pause_after_s":0.4},{"id":"s2l12","visual":"Lesson recap wording (YK.fpara 44, 'dilutes' cyan, 'does not change' gold) in the text panel on cues 'dilute' / 'بيتغير'; stage: the 8 gold dots pulse once, unchanged, on cue 'solute'. No strike-through anywhere (the line has a negation).","tts_text":"يبقى إضافة المية بتخلّي الـ solution dilute، والـ solute نفسه مش بيتغير.","screen_text":"Adding water dilutes a solution. The solute itself does not change.","pause_after_s":0.6},{"id":"s2l13","visual":"Misconception (the lesson check's wrong option 'B, because it holds more sugar'; no misconception recorded for this concept): picture change: a small glass with 6 dense gold dots (left) vs a big bucket outline with 10 sparse gold dots (right). YK.mythLine(ctx, t, {at: YK.cue('s2l13'), wrongAt: YK.cueX('s2l13','غلط'), until: YK.cueEnd('s2l14') + 1.5, text: 'More solute in total → more concentrated', x: 96, y: 300, size: 44}) with ✕ (YK.wrongMark) for its whole visible time; a ghost 'concentrated' tag over the bucket crossed by YK.wrongMark on the same cue.","tts_text":"فيه ناس فاكرة إن الـ solute الأكتر في المجموع معناه concentrated، وده غلط.","screen_text":"More solute in total → more concentrated ✕","pause_after_s":0.4},{"id":"s2l14","visual":"Fix (held ≥ the myth): two equal-size gold window frames (YK.bracket, same w × h) drop onto the glass and onto the bucket on cue 'حتة': the glass window holds 4 dots, the bucket window 1 dot; YK.fpara 'Compare the solute in each volume' (44, mint) + YK.rightMark on cue 'volume'. Myth line + ✕ stay above.","tts_text":"المهم الـ solute في كل حتة volume قدّ إيه، مش المجموع كله.","screen_text":"Compare the solute in each volume ✓","pause_after_s":0.6},{"id":"s2l15","visual":"Picture change: a lemon slice (page-local ctx arcs, flat yellow segments) on cue 'الليمون'; YK.termCard(ctx, 96, 380, {term: 'acid', align: 'left'}) on cue 'acid' + YK.fpara 'e.g. what makes lemon sour' (40, textDim).","tts_text":"فيه مادة اسمها acid، هي اللي بتدّي الليمون طعمه الحامض.","screen_text":"acid: e.g. what makes lemon sour","pause_after_s":0.4},{"id":"s2l16","visual":"Lemon slides out; a lab bottle (YK.beaker 260 × 380, clear liquid, level 0.7) slides in on cue 'المعمل' with label 'sulphuric acid' (YK.beaker label, 40) on cue 'sulphuric'.","tts_text":"ومن أشهر الـ acids في المعمل، الـ sulphuric acid ده.","screen_text":"sulphuric acid","pause_after_s":0.4},{"id":"s2l17","visual":"YK.formula(ctx, 'H2SO4', 1307, 300, {size: 96, align: 'center'}) reveals left → right above the bottle on cue 'المكتوب'; YK.termCard(ctx, 96, 380, {term: 'formula', align: 'left'}) on cue 'formula' + YK.fpara 'the short written name' (40, textDim).","tts_text":"واختصار الـ sulphuric acid المكتوب اسمه formula، اللي على الشاشة.","screen_text":"formula: H₂SO₄","pause_after_s":0.4},{"id":"s2l18","visual":"Lesson hook: two bottles side by side, both labelled YK.formula 'H2SO4' (64) on cue 'sulphuric'; under the left one tag 'dilute' (cyan) on cue 'dilute', under the right one tag 'concentrated' (gold) on cue 'concentrated'; particle insets: left few acid dots (C.amber) among many water dots, right many acid dots among few water dots.","tts_text":"في الفصل هتلاقي الـ sulphuric acid، مرة جنبه dilute ومرة concentrated كده.","screen_text":"H₂SO₄ dilute · H₂SO₄ concentrated","pause_after_s":0.4},{"id":"s2l19","visual":"Misconception (lesson hook option a + TrueFalse 'Dilute and concentrated sulphuric acid are different compounds' = false): YK.mythLine(ctx, t, {at: YK.cue('s2l19'), wrongAt: YK.cueX('s2l19','غلط'), until: YK.cueEnd('s2l21') + 1.5, text: 'Two different compounds', x: 96, y: 300, size: 48}) with ✕ for its whole visible time (no strike-through); the two bottles briefly get different coloured ghost liquids, crossed by YK.wrongMark on the same cue.","tts_text":"فيه اللي فاكر إنهم مادتين مختلفين، يعني compounds مختلفة، وده غلط.","screen_text":"Two different compounds ✕","pause_after_s":0.4},{"id":"s2l20","visual":"Fix (held ≥ the myth): the ghost colours fade, both bottles identical again; the two 'H2SO4' labels pulse together gold on cue 'sulphuric'; in the particle insets the blue water dots flash on cue 'المية' (many on the left, few on the right); YK.fpara 'Same sulphuric acid · different amounts of water' (44, mint) + YK.rightMark on cue 'مختلفة'. Myth line + ✕ stay above.","tts_text":"هو نفس الـ sulphuric acid، إنما كمية المية اللي معاه مختلفة.","screen_text":"Same sulphuric acid · different amounts of water ✓","pause_after_s":0.4},{"id":"s2l21","visual":"Water pours into the right bottle (level rises, its insets' acid dots spread) on cue 'وإضافة'; its 'H2SO4' label stays exactly the same and gets a small YK.rightMark on cue 'formula' (lesson hook option c: diluting does not change the formula). No strike-through (negated line).","tts_text":"وإضافة المية مش بتغيّر الـ formula بتاعته خالص.","screen_text":"Adding water does not change its formula ✓","pause_after_s":0.6},{"id":"s2l22","visual":"Two equal gold window frames (as in s2l14) on the two insets on cue 'volume': the concentrated window holds many amber acid dots, the dilute window few; YK.fpara 'Concentrated: much more acid in the same volume' (44) (lesson hook option b).","tts_text":"الـ concentrated فيه acid أكتر بكتير في نفس الـ volume كده.","screen_text":"Concentrated: much more acid in the same volume","pause_after_s":1},{"id":"s3l2","visual":"Lesson check data. Stage left: small YK.beaker(ctx, 1050, 700, 220, 280, {level: 0.6, label: 'A'}) with tag '5 g in 50 mL' (40) on cue 'five'; steps will stack in the text panel (YK.list, LTR, 96, 300).","tts_text":"الكوباية الأولى: five grams سكر في fifty millilitres محلول.","screen_text":"Beaker A: 5 g sugar in 50 mL","pause_after_s":0.4},{"id":"s3l3","visual":"Stage right: a big YK.beaker(ctx, 1560, 640, 420, 560, {level: 0.8, label: 'B'}) with tag '10 g in 500 mL' (40) on cue 'ten'.","tts_text":"والتانية: ten grams سكر في five hundred millilitres محلول.","screen_text":"Beaker B: 10 g sugar in 500 mL","pause_after_s":0.4},{"id":"s3l4","visual":"A gold pile icon over B grows bigger than A's on cue 'أكتر'; then B's volume bracket (dashed, tall) draws on cue 'volume'; YK.list item 'B: more sugar, much bigger volume'.","tts_text":"التانية فيها سكر أكتر، إنما الـ volume بتاعها أكبر بكتير.","screen_text":"B has more sugar in total, but a much bigger volume","pause_after_s":0.4},{"id":"s3l5","visual":"YK.list item 'sugar in each mL = sugar ÷ volume' (÷ via YK.formula; draw as a path if the font lacks it) on cue 'نقسم'; a tiny '1 mL' cube (YK.cube s 40) appears beside each beaker on cue 'المللي'.","tts_text":"عشان نقارن صح، نقسم السكر على الـ volume، ونشوف المللي الواحد.","screen_text":"Sugar in each mL: divide","pause_after_s":0.4},{"id":"s3l6","visual":"YK.list item 'A: 5 ÷ 50 = 0.1 g in each mL' builds on cues 'five' / 'fifty' / 'one'; A's tiny cube fills with gold dots (dense) on cue 'grams'.","tts_text":"الأولى: five divided by fifty equals zero point one grams في المللي.","screen_text":"A: 5 ÷ 50 = 0.1 g in each mL","pause_after_s":0.4},{"id":"s3l7","visual":"YK.list item 'B: 10 ÷ 500 = 0.02 g in each mL' builds on cues 'ten' / 'five' / 'two'; B's tiny cube gets only a few gold dots (sparse) on cue 'grams'.","tts_text":"التانية: ten divided by five hundred equals zero point zero two grams بس.","screen_text":"B: 10 ÷ 500 = 0.02 g in each mL","pause_after_s":0.4},{"id":"s3l8","visual":"Result: YK.answerSlot(ctx, t, {at: YK.cueX('s3l8','أكبر'), text: 'A is more concentrated', x: 420, y: 880}); beaker A glows gold, tag 'concentrated' on it on cue 'concentrated'.","tts_text":"الـ zero point one أكبر، يبقى الأولى هي الـ concentrated أكتر.","screen_text":"0.1 > 0.02 → A is more concentrated ✓","pause_after_s":0.4},{"id":"s3l9","visual":"The two tiny cubes side by side enlarge (dense A vs sparse B) on cue 'مللي'; A's pile icon stays smaller than B's (contrast held); YK.fpara 'Less sugar in total, but more in each mL' (40, mint).","tts_text":"مع إن السكر فيها أقل في المجموع، إنما هو أكتر في كل مللي.","screen_text":"Less sugar in total, but more in each mL","pause_after_s":0.6},{"id":"s3l10","visual":"Self-check on a NEW case (numbers not in the lesson): stage clears; two beakers with tags '6 g in 200 mL' (left, on cue 'six') and '3 g in 50 mL' (right, on cue 'three'); no dots drawn (no hint). YK.predictCard(ctx, t, {at: YK.cue('s3l10'), until: YK.cue('s3l12') + 0.4, think: YK.cueEnd('s3l11'), end: YK.cue('s3l12'), kind: 'QUICK CHECK', q: 'Which is more concentrated: 6 g in 200 mL or 3 g in 50 mL?'}).","tts_text":"دورك: أنهي concentrated أكتر؟ six grams في two hundred millilitres، ولا three grams في fifty كمان؟","screen_text":"Your turn: 6 g in 200 mL or 3 g in 50 mL?","pause_after_s":0.4},{"id":"s3l11","visual":"The question stays; YK.checkPause(ctx, 1307, 860, {t, start: YK.cueEnd('s3l11'), dur: 4}) think ring + countdown through the silence; only the question shows (no answer, no division shown).","tts_text":"وقّف الفيديو، واقسِم زي ما عملنا في المثال.","screen_text":"Pause: divide each","pause_after_s":4},{"id":"s3l12","visual":"Answer: the right beaker glows gold on cue 'الإجابة'; YK.answerSlot(ctx, t, {at: YK.cueX('s3l12','الإجابة'), text: '3 g in 50 mL', x: 420, y: 700}).","tts_text":"الإجابة: الـ three grams في fifty millilitres هي الـ concentrated أكتر.","screen_text":"3 g in 50 mL ✓","pause_after_s":0.4},{"id":"s3l13","visual":"Reason line 1 (YK.fpara mono 48, mint) builds on cues 'three' / 'fifty' / 'six'; the right beaker's tiny 1 mL cube fills with denser dots.","tts_text":"السبب: three divided by fifty equals zero point zero six grams في المللي.","screen_text":"3 ÷ 50 = 0.06 g in each mL","pause_after_s":0.4},{"id":"s3l14","visual":"Reason line 2 under it builds on cues 'six' / 'two#1' / 'three'; the left beaker's tiny cube gets fewer dots; both cubes side by side (dense right, sparse left) and a small YK.rightMark next to line 1.","tts_text":"و six divided by two hundred equals zero point zero three grams بس.","screen_text":"6 ÷ 200 = 0.03 g in each mL","pause_after_s":1},{"id":"s4l1","visual":"Header 'Where Chapter 1 uses this' in the text panel on the line start (no part card); the example stage fades out.","tts_text":"طب الكلام ده هيفيدك فين في الفصل؟","screen_text":"Where Chapter 1 uses this","pause_after_s":2},{"id":"s4l2","visual":"YK.chip(ctx, 820, 220, 'Iron with dilute acids', {kind: 'concept', align: 'left'}) (map title_en exactly) on cue 'iron'; a grey iron piece (YK.cube s 70, C.steel, no label) beside it on cue 'الحديد'.","tts_text":"في الفصل هتقابل درس الـ iron مع الـ dilute acids، يعني الحديد.","screen_text":"Iron with dilute acids","pause_after_s":0.4},{"id":"s4l3","visual":"Second YK.chip(ctx, 820, 420, 'Iron with hot concentrated sulphuric acid', {kind: 'concept', align: 'left'}) (map title_en exactly) on cue 'iron'; 'concentrated' in the chip pulses gold on cue 'concentrated'.","tts_text":"ودرس الـ iron مع الـ sulphuric acid الـ concentrated السخن كمان.","screen_text":"Iron with hot concentrated sulphuric acid","pause_after_s":0.4},{"id":"s4l4","visual":"The two H2SO4 bottles of s2l18 return small under the chips: 'dilute' bottle linked (thin gold line) to chip 1 on cue 'dilute', 'concentrated' bottle linked to chip 2 on cue 'concentrated'.","tts_text":"الاتنين فيهم الـ sulphuric acid، مرة dilute ومرة concentrated كده.","screen_text":"sulphuric acid: dilute in one, concentrated in the other","pause_after_s":0.4},{"id":"s4l5","visual":"Two empty outlined result boxes (YK.panel, dashed, with a '?' drawn as a path) at the end of each link on cue 'مختلفة'; YK.fpara 'details in the chapter' (40, textDim) on cue 'والتفاصيل'. No products named, no gas shown (lesson Next note: iron gives different products with dilute and with hot concentrated sulphuric acid).","tts_text":"والـ iron بيدّي حاجات مختلفة في الحالتين، والتفاصيل في الفصل.","screen_text":"iron: different results · details in the chapter","pause_after_s":0.6},{"id":"s4l6","visual":"Recap (s4l6–s4l7 ≤ 20 s): YK.recapCard(ctx, t, {at: YK.cue('s4l6'), until: YK.cue('s4l8'), title: 'Concentrated and dilute solutions', line: 'Concentrated: much solute in a given volume · Dilute: little', pulse: [{word: 'Concentrated', at: YK.cueX('s4l6','concentrated')}, {word: 'Dilute', at: YK.cueX('s4l6','dilute')}]}); stage: the two glasses of s2 return small (dense right, sparse left).","tts_text":"الخلاصة: الـ concentrated فيه solute كتير في الـ volume، والـ dilute فيه قليل.","screen_text":"Concentrated: much solute in a given volume · Dilute: little","pause_after_s":0.4},{"id":"s4l7","visual":"Same recap card, second line 'Adding water dilutes; the solute does not change' added on cue 'المية'; on the stage water pours into the dense glass and its dots spread on cue 'dilute'.","tts_text":"والمية بتخلّي الـ solution dilute أكتر، والـ solute نفسه زي ما هو.","screen_text":"Adding water dilutes; the solute does not change","pause_after_s":0.6},{"id":"s4l8","visual":"Voiced lock-in = takeaway: YK.takeaway(ctx, {title: 'Concentrated and dilute solutions', line: 'Compare the solute in the same volume.', t, pulse: [{word: 'solute', at: YK.cueX('s4l8','solute')}, {word: 'volume', at: YK.cueX('s4l8','volume')}]}) held ≥ 2.5 s; no fade to black, no outro.","tts_text":"يعني قارن الـ solute في نفس الـ volume كده.","screen_text":"Compare the solute in the same volume.","pause_after_s":1.5}],"logline":"هتعرف يعني إيه solution و solute و solvent، وتفرّق بين الـ concentrated والـ dilute بإنك تقارن الـ solute في نفس الـ volume.","segments":[{"id":"s1","title":"Sugar in a glass of water","concept_id":"chem.solution-concentration"},{"id":"s2","title":"Concentrated and dilute solutions","concept_id":"chem.solution-concentration"},{"id":"s3","title":"Which solution is more concentrated?","concept_id":"chem.solution-concentration"},{"id":"s4","title":"Where Chapter 1 uses 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كوباية مَيّة وحطّينا فيها معلقة سكر\nوقلّبناها كويس\nالسكر بيختفي من قدام عينك إنما طعم المية\nبقى مسكّر\nلو كبّرنا جدًا هنلاقي حبيبات السكر متفرقة\nوسط حبيبات المية\nالخليط ده اللي السكر دايب فيه في المية\nاسمه solution كده\nوالحاجة اللي دابت هنا السكر اسمها solute\nكده\nوالحاجة اللي دابت فيها اسمها solvent زي\nالمية هنا مثلًا\nيعني الـ solution هو solute دايب في\nsolvent زي السكر في المية\nدلوقتي كوبايتين قد بعض واحدة فيها معلقة\nوالتانية خمس معالق\nأنهي كوباية هتبقى أحلى في الطعم فكّر قبل\nما أقولك\nاللي فيها خمس معالق عشان فيها سكر أكتر في\nنفس الكمية\nالكمية دي يعني المكان اللي المحلول واخده\nاسمها volume وبنقيسها بالمللي\nالمحلول اللي فيه solute كتير في volume\nمعين اسمه concentrated solution كده\nواللي فيه solute قليل في نفس الـ volume\nاسمه dilute solution كده\nيعني أم خمس معالق concentrated وأم معلقة\nواحدة dilute مقارنة ببعض\nطب لو زوّدنا مَيّة على الكوباية التقيلة\nالـ solute نفسه مش هيزيد\nنفس الـ eight حبيبات إنما المية بقت four\nhundred millilitres بدل one hundred بس\nفكل one hundred millilitres بقى فيها two\nحبيبات بس بدل eight يعني dilute أكتر\nيبقى إضافة المية بتخلّي الـ solution\ndilute والـ solute نفسه مش بيتغير\nفيه ناس فاكرة إن الـ solute الأكتر في\nالمجموع معناه concentrated وده غلط\nالمهم الـ solute في كل حتة volume قد إيه\nمش المجموع كله\nفيه مادة اسمها acid هي اللي بتدّي الليمون\nطعمه الحامض\nومن أشهر الـ acids في المعمل الـ sulphuric\nacid ده\nواختصار الـ sulphuric acid المكتوب اسمه\nformula اللي على الشاشة\nفي الفصل هتلاقي الـ sulphuric acid مرة\nجنبه dilute ومرة concentrated كده\nفيه اللي فاكر إنهم مادتين مختلفين يعني\ncompounds مختلفة وده غلط\nهو نفس الـ sulphuric acid إنما كمية المية\nاللي معاه مختلفة\nوإضافة المية مش بتغيّر الـ formula بتاعته\nخالص\nالـ concentrated فيه acid أكتر بكتير في\nنفس الـ volume كده\nالكوباية الأولى five grams سكر في fifty\nmillilitres محلول\nوالتانية ten grams سكر في five hundred\nmillilitres محلول\nالتانية فيها سكر أكتر إنما الـ volume\nبتاعها أكبر بكتير\nعشان نقارن صح نقسم السكر على الـ volume\nونشوف المللي الواحد\nالأولى five divided by fifty equals zero\npoint one grams في المللي\nالتانية ten divided by five hundred equals\nzero point zero two grams بس\nالـ zero point one أكبر يبقى الأولى هي الـ\nconcentrated أكتر\nمع إن السكر فيها أقل في المجموع إنما هو\nأكتر في كل مللي\nدورك أنهي concentrated أكتر six grams في\ntwo hundred millilitres ولا three grams في\nfifty كمان\nوقّف الفيديو واقسِم زي ما عملنا في المثال\nالإجابة الـ three grams في fifty\nmillilitres هي الـ concentrated أكتر\nالسبب three divided by fifty equals zero\npoint zero six grams في المللي\nو six divided by two hundred equals zero\npoint zero three grams بس\nطب الكلام ده هيفيدك فين في الفصل\nفي الفصل هتقابل درس الـ iron مع الـ dilute\nacids يعني الحديد\nودرس الـ iron مع الـ sulphuric acid الـ\nconcentrated السخن كمان\nالاتنين فيهم الـ sulphuric acid مرة dilute\nومرة concentrated كده\nوالـ iron بيدّي حاجات مختلفة في الحالتين\nوالتفاصيل في الفصل\nالخلاصة الـ concentrated فيه solute كتير\nفي الـ volume والـ dilute فيه قليل\nوالمية بتخلّي الـ solution dilute أكتر\nوالـ solute نفسه زي ما هو\nيعني قارن الـ solute في نفس الـ volume كده","countable":false,"session_id":"chem-s3-en.ch1.s8","session_no":8,"session_ord":46,"see_also":[{"item_id":"chem-s3-en.lesson-fe.reaction-dilute-acids","kind":"lesson","chapter_id":"chem-s3-en.ch1","title":"Iron with dilute acids","duration_s":0,"ord":0,"in_release":true,"content_lang":"ar-EG"}],"cues":[{"id":"think-1","t_s":50.88,"kind":"pause_question","spec":{"answer":"اللي فيها 5 معالق: سكر أكتر في نفس كمية المية.","prompt":"كوبايتين فيهم نفس كمية المية: واحدة فيها معلقة سكر، والتانية 5 معالق. أنهي أحلى؟","options":[{"id":"a","text":"اللي فيها 5 معالق","correct":true},{"id":"b","text":"الاتنين زي بعض","correct":false}],"answer_t_s":54.64,"concept_id":"chem.solution-concentration"},"content_lang":"ar-EG"},{"id":"think-2","t_s":212.15,"kind":"pause_question","spec":{"answer":"3 ÷ 50 = 0.06 g في كل mL، و 6 ÷ 200 = 0.03 g؛ يبقى 3 g في 50 mL هو الـ concentrated أكتر.","prompt":"6 g في 200 mL ولا 3 g في 50 mL: أنهي concentrated أكتر؟","options":[{"id":"a","text":"3 g في 50 mL","correct":true},{"id":"b","text":"6 g في 200 mL، عشان فيه solute أكتر","correct":false}],"answer_t_s":216.15,"concept_id":"chem.solution-concentration"},"content_lang":"ar-EG"}],"lessons":["chem-s3-en.lesson-chem.solution-concentration"]}],"sessions":[{"id":"chem-s3-en.ch1.s1","ord":1,"n":1,"title":"The transition elements and their series","summaries":{"ar-EG":"هتفهم الـ transition elements قاعدين فين في الجدول، والـ four series بتاعتهم متكوّنة إزاي.","en":"Where the transition elements sit in the periodic table and how their four series are built."},"summary":"هتفهم الـ transition elements قاعدين فين في الجدول، والـ four series بتاعتهم متكوّنة إزاي.","summary_lang":"ar-EG","episode_item_id":"chem-s3-en.video-episode-te-position","basics_ids":["chem-s3-en.lesson-phys.electric-charges","chem-s3-en.lesson-sci.matter-particles","chem-s3-en.lesson-atom.atomic-mass-number","chem-s3-en.lesson-atom.energy-levels","chem-s3-en.lesson-chem.elements-symbols","chem-s3-en.lesson-pt.groups-periods","chem-s3-en.lesson-atom.sublevels","chem-s3-en.lesson-atom.orbitals","chem-s3-en.lesson-atom.aufbau","chem-s3-en.lesson-phys.magnetic-field","chem-s3-en.lesson-atom.electron-spin-pauli","chem-s3-en.lesson-atom.electron-configuration-writing","chem-s3-en.lesson-pt.blocks"],"lesson_ids":["chem-s3-en.lesson-te.position-in-periodic-table","chem-s3-en.lesson-te.d-block-groups","chem-s3-en.lesson-te.transition-series","chem-s3-en.lesson-te.first-series-elements"],"other_ids":["chem-s3-en.video-short-phys.electric-charges","chem-s3-en.video-short-sci.matter-particles","chem-s3-en.video-short-atom.atomic-mass-number","chem-s3-en.video-short-atom.energy-levels","chem-s3-en.video-short-chem.elements-symbols","chem-s3-en.video-short-pt.groups-periods","chem-s3-en.video-short-atom.sublevels","chem-s3-en.video-short-atom.orbitals","chem-s3-en.video-short-atom.aufbau","chem-s3-en.video-short-phys.magnetic-field","chem-s3-en.video-short-atom.electron-spin-pauli","chem-s3-en.video-short-atom.electron-configuration-writing","chem-s3-en.video-short-pt.blocks","chem-s3-en.video-short-te.position-in-periodic-table","chem-s3-en.video-short-te.d-block-groups","chem-s3-en.video-short-te.transition-series","chem-s3-en.video-short-te.first-series-elements","chem-s3-en.question-phys.electric-charges-1","chem-s3-en.question-phys.electric-charges-2","chem-s3-en.question-sci.matter-particles-1","chem-s3-en.question-sci.matter-particles-2","chem-s3-en.question-atom.atomic-mass-number-1","chem-s3-en.question-atom.atomic-mass-number-2","chem-s3-en.question-atom.energy-levels-1","chem-s3-en.question-atom.energy-levels-2","chem-s3-en.question-chem.elements-symbols-1","chem-s3-en.question-chem.elements-symbols-2","chem-s3-en.question-pt.groups-periods-1","chem-s3-en.question-pt.groups-periods-2","chem-s3-en.question-atom.sublevels-1","chem-s3-en.question-atom.sublevels-2","chem-s3-en.question-atom.orbitals-1","chem-s3-en.question-atom.orbitals-2","chem-s3-en.question-atom.aufbau-1","chem-s3-en.question-atom.aufbau-2","chem-s3-en.question-phys.magnetic-field-1","chem-s3-en.question-phys.magnetic-field-2","chem-s3-en.question-atom.electron-spin-pauli-1","chem-s3-en.question-atom.electron-spin-pauli-2","chem-s3-en.question-atom.electron-configuration-writing-1","chem-s3-en.question-atom.electron-configuration-writing-2","chem-s3-en.question-pt.blocks-1","chem-s3-en.question-pt.blocks-2","chem-s3-en.question-te.position-in-periodic-table-1","chem-s3-en.question-te.d-block-groups-1","chem-s3-en.question-te.transition-series-1","chem-s3-en.question-te.first-series-elements-1","chem-s3-en.question-te.position-in-periodic-table-2","chem-s3-en.question-te.d-block-groups-2","chem-s3-en.question-te.transition-series-2","chem-s3-en.question-te.first-series-elements-2","chem-s3-en.question-te.position-in-periodic-table-3","chem-s3-en.question-te.d-block-groups-3","chem-s3-en.question-te.transition-series-3","chem-s3-en.question-te.first-series-elements-3","chem-s3-en.question-te.first-series-elements-4","chem-s3-en.question-te.d-block-groups-4","chem-s3-en.question-te.transition-series-4","chem-s3-en.question-te.first-series-elements-5","chem-s3-en.video-walkthrough-phys.electric-charges","chem-s3-en.video-walkthrough-sci.matter-particles","chem-s3-en.video-walkthrough-atom.atomic-mass-number","chem-s3-en.video-walkthrough-atom.energy-levels","chem-s3-en.video-walkthrough-chem.elements-symbols","chem-s3-en.video-walkthrough-pt.groups-periods","chem-s3-en.video-walkthrough-atom.sublevels","chem-s3-en.video-walkthrough-atom.orbitals","chem-s3-en.video-walkthrough-atom.aufbau","chem-s3-en.video-walkthrough-phys.magnetic-field","chem-s3-en.video-walkthrough-atom.electron-spin-pauli"],"item_ids":["chem-s3-en.lesson-phys.electric-charges","chem-s3-en.lesson-sci.matter-particles","chem-s3-en.lesson-atom.atomic-mass-number","chem-s3-en.lesson-atom.energy-levels","chem-s3-en.lesson-chem.elements-symbols","chem-s3-en.lesson-pt.groups-periods","chem-s3-en.lesson-atom.sublevels","chem-s3-en.lesson-atom.orbitals","chem-s3-en.lesson-atom.aufbau","chem-s3-en.lesson-phys.magnetic-field","chem-s3-en.lesson-atom.electron-spin-pauli","chem-s3-en.lesson-atom.electron-configuration-writing","chem-s3-en.lesson-pt.blocks","chem-s3-en.lesson-te.position-in-periodic-table","chem-s3-en.lesson-te.d-block-groups","chem-s3-en.lesson-te.transition-series","chem-s3-en.lesson-te.first-series-elements","chem-s3-en.video-short-phys.electric-charges","chem-s3-en.video-short-sci.matter-particles","chem-s3-en.video-short-atom.atomic-mass-number","chem-s3-en.video-short-atom.energy-levels","chem-s3-en.video-short-chem.elements-symbols","chem-s3-en.vid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عالية.","summary_lang":"ar-EG","episode_item_id":"chem-s3-en.video-episode-te-physical-properties","basics_ids":["chem-s3-en.lesson-phys.states-melting-boiling","chem-s3-en.lesson-bond.chemical-bond-basic","chem-s3-en.lesson-bond.metallic-bond","chem-s3-en.lesson-phys.density"],"lesson_ids":["chem-s3-en.lesson-te.atomic-mass-trend","chem-s3-en.lesson-te.atomic-radius","chem-s3-en.lesson-te.metallic-properties","chem-s3-en.lesson-te.high-melting-points","chem-s3-en.lesson-te.density-trend"],"other_ids":["chem-s3-en.video-short-te.atomic-mass-trend","chem-s3-en.video-short-te.atomic-radius","chem-s3-en.video-short-te.metallic-properties","chem-s3-en.video-short-phys.states-melting-boiling","chem-s3-en.video-short-bond.chemical-bond-basic","chem-s3-en.video-short-bond.metallic-bond","chem-s3-en.video-short-te.high-melting-points","chem-s3-en.video-short-phys.density","chem-s3-en.video-short-te.density-trend","chem-s3-en.question-phys.states-melting-boiling-1","chem-s3-en.question-phys.states-melting-boiling-2","chem-s3-en.question-bond.chemical-bond-basic-1","chem-s3-en.question-bond.chemical-bond-basic-2","chem-s3-en.question-bond.metallic-bond-1","chem-s3-en.question-bond.metallic-bond-2","chem-s3-en.question-phys.density-1","chem-s3-en.question-phys.density-2","chem-s3-en.question-te.atomic-mass-trend-1","chem-s3-en.question-te.atomic-radius-1","chem-s3-en.question-te.metallic-properties-1","chem-s3-en.question-te.high-melting-points-1","chem-s3-en.question-te.density-trend-1","chem-s3-en.question-te.atomic-mass-trend-2","chem-s3-en.question-te.atomic-radius-2","chem-s3-en.question-te.metallic-properties-2","chem-s3-en.question-te.high-melting-points-2","chem-s3-en.question-te.density-trend-2","chem-s3-en.question-te.atomic-mass-trend-3","chem-s3-en.question-te.atomic-radius-3","chem-s3-en.question-te.metallic-properties-3","chem-s3-en.question-te.high-melting-points-3","chem-s3-en.question-te.density-trend-3","chem-s3-en.question-te.atomic-radius-4","chem-s3-en.question-te.atomic-radius-5","chem-s3-en.question-te.atomic-radius-6","chem-s3-en.question-te.density-trend-4","chem-s3-en.video-walkthrough-bond.chemical-bond-basic"],"item_ids":["chem-s3-en.lesson-phys.states-melting-boiling","chem-s3-en.lesson-bond.chemical-bond-basic","chem-s3-en.lesson-bond.metallic-bond","chem-s3-en.lesson-phys.density","chem-s3-en.lesson-te.atomic-mass-trend","chem-s3-en.lesson-te.atomic-radius","chem-s3-en.lesson-te.metallic-properties","chem-s3-en.lesson-te.high-melting-points","chem-s3-en.lesson-te.density-trend","chem-s3-en.video-short-te.atomic-mass-trend","chem-s3-en.video-short-te.atomic-radius","chem-s3-en.video-short-te.metallic-properties","chem-s3-en.video-short-phys.states-melting-boiling","chem-s3-en.video-short-bond.chemical-bond-basic","chem-s3-en.video-short-bond.metallic-bond","chem-s3-en.video-short-te.high-melting-points","chem-s3-en.video-short-phys.density","chem-s3-en.video-short-te.density-trend","chem-s3-en.question-phys.states-melting-boiling-1","chem-s3-en.question-phys.states-melting-boiling-2","chem-s3-en.question-bond.chemical-bond-basic-1","chem-s3-en.question-bond.chemical-bond-basic-2","chem-s3-en.question-bond.metallic-bond-1","chem-s3-en.question-bond.metallic-bond-2","chem-s3-en.question-phys.density-1","chem-s3-en.question-phys.density-2","chem-s3-en.question-te.atomic-mass-trend-1","chem-s3-en.question-te.atomic-radius-1","chem-s3-en.question-te.metallic-properties-1","chem-s3-en.question-te.high-melting-points-1","chem-s3-en.question-te.density-trend-1","chem-s3-en.question-te.atomic-mass-trend-2","chem-s3-en.question-te.atomic-radius-2","chem-s3-en.question-te.metallic-properties-2","chem-s3-en.question-te.high-melting-points-2","chem-s3-en.question-te.density-trend-2","chem-s3-en.question-te.atomic-mass-trend-3","chem-s3-en.question-te.atomic-radius-3","chem-s3-en.question-te.metallic-properties-3","chem-s3-en.question-te.high-melting-points-3","chem-s3-en.question-te.density-trend-3","chem-s3-en.question-te.atomic-radius-4","chem-s3-en.question-te.atomic-radius-5","chem-s3-en.question-te.atomic-radius-6","chem-s3-en.question-te.density-trend-4","chem-s3-en.video-walkthrough-bond.chemical-bond-basic","chem-s3-en.video-episode-te-physical-properties"],"counts":{"lessons":9,"basics":4,"countable":46}},{"id":"chem-s3-en.ch1.s5","ord":5,"n":5,"title":"Magnetic 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