{"id":7283,"date":"2026-09-08T19:03:16","date_gmt":"2026-09-08T18:03:16","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/alkene-bonding\/"},"modified":"2026-09-22T08:04:38","modified_gmt":"2026-09-22T07:04:38","slug":"alkene-bonding","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/alkene-bonding\/","title":{"rendered":"Alkene Bonding"},"content":{"rendered":"<script src=\"https:\/\/cdnjs.cloudflare.com\/ajax\/libs\/three.js\/r128\/three.min.js\"><\/script>\n\n<section class=\"ols-revision-page ols-alkene-bonding-page\">\n  <style>\n    .ols-revision-page {\n      --navy: #1C244B;\n      --blue: #2563eb;\n      --soft-blue: #eef4ff;\n      --soft-red: #fff7f7;\n      --soft-purple: #f7f0ff;\n      --soft-green: #f0f7f1;\n      --gold: #c9973a;\n      --grey-text: #667085;\n      --body-text: #1f2937;\n      --border: 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14px;\n      line-height: 1.65;\n      font-weight: 300;\n      color: #667085;\n    }\n    .ols-attribution-card strong { font-weight: 700; color: #1C244B; }\n  <\/style>\n\n    <aside class=\"ols-sidebar\">\n  <div class=\"ols-sidebar-header\">\n    <h3>Revision Notes<\/h3>\n    <p>AQA A Level Chemistry<\/p>\n  <\/div>\n\n  <div class=\"ols-topic-group\">\n    <h4>3.3.4 Alkenes<\/h4>\n\n    <ul class=\"ols-topic-list\">\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/alkene-bonding\/\">Alkene Bonding<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/geometric-isomerism\/\">E-Z Isomerism<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/electrophilic-addition-mechanism\/\">Electrophilic Addition Mechanism<\/a><\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/reactions-of-alkenes\/\">Reactions of Alkenes<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/reactions-of-alkenes\/halogens\/\">Halogens<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/reactions-of-alkenes\/hydrogen-halide\/\">Hydrogen Halide<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/reactions-of-alkenes\/sulfuric-acid\/\">Sulfuric Acid<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/reactions-of-alkenes\/bromine-water\/\">Bromine Water<\/a><\/li>\n          <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/reactions-of-alkenes\/steam\/\">Steam<\/a><\/li>\n        <\/ul>\n      <\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/polymerisation-reactions\/\">Addition Polymers<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/polymer-properties-and-pvc\/\">Polymer Properties and PVC<\/a><\/li>\n    <\/ul>\n  <\/div>\n\n  <div class=\"ols-topic-group\">\n    <h4>Other AQA Sections<\/h4>\n    <ul class=\"ols-topic-list\">\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-1-introduction-to-organic-chemistry\/\">3.3.1 Introduction to Organic Chemistry<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-2-alkanes\/\">3.3.2 Alkanes<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-1-atomicstructure\/\">3.1.1 Atomic Structure<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-2-amount-of-substance\/\">3.1.2 Amount of Substance<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-1-3-bonding\/\">3.1.3 Bonding<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-2-1-periodicity\/\">3.2.1 Periodicity<\/a><\/li>\n    <\/ul>\n  <\/div>\n<\/aside>\n<script>\r\n(function() {\r\n  function normalisePath(path) {\r\n    return String(path || '')\r\n      .split('?')[0]\r\n      .split('#')[0]\r\n      .replace(\/\\\/+$\/, '')\r\n      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class=\"ols-breadcrumbs\" aria-label=\"Breadcrumb\">\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\">Revision Notes<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\">A Level Chemistry<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/\">AQA<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/aqa\/3-3-4-alkenes\/\">3.3.4 Alkenes<\/a> \/\n<span>Alkene Bonding<\/span>\n<\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Alkene Bonding<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to alkene structure, carbon-carbon double bonds, sigma bonds, pi bonds and why alkenes are more reactive than alkanes.<\/p>\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Paper 2<\/div>\n<div class=\"ols-badge\">AQA<\/div>\n<div class=\"ols-badge\">3.3.4 Alkenes<\/div>\n<div class=\"ols-badge\">7405\/2<\/div>\n        <\/div>\n        <div class=\"ols-author\">\n\n    <img decoding=\"async\"\n      class=\"ols-author-avatar-img\"\n      src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Author-Profile.jpeg\"\n      alt=\"Dr. Mohammed Al-Fatah\"\n    >\n\n    <div class=\"ols-author-content\">\n\n      <h2 class=\"ols-author-title\">\n        Written by: Dr. Mohammed Al-Fatah\n      <\/h2>\n\n      <p class=\"ols-author-description\">\n        Chemistry specialist revision notes for A Level Chemistry.\n      <\/p>\n\n      <a class=\"ols-linkedin-pill\" href=\"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\" target=\"_blank\" rel=\"noopener noreferrer\">\n        <svg class=\"ols-linkedin-icon\" viewBox=\"0 0 24 24\" fill=\"currentColor\" aria-hidden=\"true\">\n          <path d=\"M4.98 3.5C4.98 4.88 3.86 6 2.48 6S0 4.88 0 3.5 1.12 1 2.48 1s2.5 1.12 2.5 2.5zM.5 8h4V24h-4V8zm7 0h3.8v2.2h.1c.5-.9 1.8-2.2 3.9-2.2 4.2 0 5 2.8 5 6.4V24h-4v-7.6c0-1.8 0-4.2-2.6-4.2s-3 2-3 4v7.8h-4V8z\"\/>\n        <\/svg>\n        View LinkedIn Profile\n      <\/a>\n\n    <\/div>\n\n  <\/div>\n      <\/header>\n\n      <section class=\"ols-h5p-card ols-h5p-inline ols-h5p-recap\">\n<span class=\"ols-h5p-kicker\">Before you start<\/span>\n<h2>GCSE Recap: Shared Pairs of Electrons<\/h2>\n<p>Three quick questions on single and double covalent bonds before you look inside the C=C bond.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"732\"><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">1<\/div><h2>What Makes an Alkene Unsaturated?<\/h2><\/div>\n        <p>Alkenes are hydrocarbons described as <strong>unsaturated<\/strong>. This means they do not contain the maximum possible number of hydrogen atoms.<\/p>\n        <p>The key structural feature of an alkene is at least one <strong>carbon-carbon double bond<\/strong>, written as <strong>C=C<\/strong>. For alkenes with one double bond and no rings, the general formula is <strong>C<sub>n<\/sub>H<sub>2n<\/sub><\/strong>.<\/p>\n        <p>Small alkenes include <strong>ethene<\/strong>, <strong>propene<\/strong> and <strong>butene<\/strong>. In longer alkenes, the position of the double bond can change, producing <strong>positional isomers<\/strong> such as but-1-ene and but-2-ene.<\/p>\n        <div class=\"ols-key-box\"><p><strong>Key idea:<\/strong> An alkene must contain a C=C double bond, and this double bond is responsible for the characteristic chemistry of alkenes.<\/p><\/div>\n        <div class=\"ols-figure-card ols-zoom-pop\">\n          <div class=\"ols-figure-image\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/alkenes-overview-positional-isomerism.webp\" role=\"img\" aria-label=\"Examples of alkenes showing ethene, propene, but-1-ene and but-2-ene with the general formula CnH2n\" style=\"--ols-image: url('https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/alkenes-overview-positional-isomerism.webp');\"><\/div>\n          <div class=\"ols-figure-caption\">\n            <h3>Alkenes and positional isomers<\/h3>\n            <p>Shows unsaturation, the C=C bond, C<sub>n<\/sub>H<sub>2n<\/sub>, and how butene can exist as but-1-ene or but-2-ene.<\/p>\n          <\/div>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Formulae and Positional Isomers<\/h2>\n<p>Apply the general formula to alkenes that are not named on this page.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-3\" class=\"h5p-iframe\" data-content-id=\"3\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Alkene Bonding Quick-Fire: General Formula and Positional Isomers\"><\/iframe><\/div><\/div>\n<\/section>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: A Ring as Well as a Double Bond<\/h2>\n<p>Work out how the general formula changes when the alkene is cyclic.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-16\" class=\"h5p-iframe\" data-content-id=\"16\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Cyclohexene General Formula\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">2<\/div><h2>The Carbon-Carbon Double Bond<\/h2><\/div>\n        <p>A carbon-carbon double bond is made from <strong>two different covalent bonds<\/strong>: one <strong>sigma, \u03c3, bond<\/strong> and one <strong>pi, \u03c0, bond<\/strong>.<\/p>\n        <p>The sigma bond forms first and lies directly between the two carbon nuclei. The pi bond forms from sideways overlap of p orbitals, giving electron density above and below the plane of the molecule.<\/p>\n        <p>The pi bond is more exposed than the sigma bond. This creates a region of <strong>high electron density<\/strong> that can attract electron-deficient species called <strong>electrophiles<\/strong>.<\/p>\n        <div class=\"ols-key-box\"><p><strong>Exam focus:<\/strong> When explaining alkene reactivity, link the exposed pi bond to high electron density and attraction to electrophiles.<\/p><\/div>\n        <div class=\"ols-figure-card ols-zoom-pop\">\n          <div class=\"ols-figure-image\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/carbon-carbon-double-bond-sigma-pi-bond.webp\" role=\"img\" aria-label=\"Diagram showing a carbon-carbon double bond made from one sigma bond and one pi bond\" style=\"--ols-image: url('https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/carbon-carbon-double-bond-sigma-pi-bond.webp');\"><\/div>\n          <div class=\"ols-figure-caption\">\n            <p>The C=C double bond contains one sigma bond and one pi bond, with the pi bond forming above and below the molecular plane.<\/p>\n          <\/div>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Count the \u03c3 and \u03c0 Bonds<\/h2>\n<p>Count every bond in the molecule shown, remembering what each double bond contains.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-296\" class=\"h5p-iframe\" data-content-id=\"296\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Sigma and pi bonds in a cumulated diene molecule\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">3<\/div><h2>Formation of the Sigma Bond<\/h2><\/div>\n        <p>When two carbon atoms form a double bond, each carbon uses one <strong>sp<sup>2<\/sup> hybrid orbital<\/strong> to overlap directly with the other carbon atom.<\/p>\n        <p>This direct head-on overlap produces a strong <strong>carbon-carbon sigma bond<\/strong>. The electron density is concentrated between the two nuclei, so the sigma bond lies along the straight line joining the nuclei.<\/p>\n        <p>A single sigma bond allows free rotation around the bond axis. However, in a C=C double bond, this rotation is restricted because the pi bond must also be maintained.<\/p>\n        <div class=\"ols-key-box\"><p><strong>Remember:<\/strong> Sigma bonds are formed by direct overlap along the internuclear axis.<\/p><\/div>\n        <div class=\"ols-figure-card ols-zoom-pop\">\n          <div class=\"ols-figure-image\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/sigma-bond-formation-sp2-overlap.png.webp\" role=\"img\" aria-label=\"Head-on orbital overlap forming a sigma bond between two carbon atoms\" style=\"--ols-image: url('https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/sigma-bond-formation-sp2-overlap.png.webp');\"><\/div>\n          <div class=\"ols-figure-caption\">\n            <p>Direct head-on overlap places electron density between the nuclei, forming the first bond in the carbon-carbon double bond.<\/p>\n          <\/div>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Which Bond Can Rotate?<\/h2>\n<p>Decide where rotation is possible in two molecules that are not on this page.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-9\" class=\"h5p-iframe\" data-content-id=\"9\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Alkene Bonding MCQ: Rotation in 1,2-Dichloroethane and 1,2-Dichloroethene\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <!-- SIGMA 3D MODEL -->\n      <section class=\"ols-sigma-card-001\">\n        <style>\n          .ols-sigma-card-001 { width:100%;max-width:1180px;margin:0 auto 34px auto;font-family:Poppins,Arial,sans-serif;box-sizing:border-box; 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}\n            .ols-sigma-card-001 .ols-sigma-card{padding:22px 14px;border-radius:22px;}\n            .ols-sigma-card-001 .ols-sigma-viewer-wrap{height:520px;border-radius:20px;}\n            .ols-sigma-card-001 .ols-sigma-subtitle{font-size:16px;}\n            .ols-sigma-card-001 .ols-sigma-controls{top:12px;left:12px;right:12px;display:grid;grid-template-columns:1fr;gap:8px;}\n            .ols-sigma-card-001 .ols-sigma-btn{width:100%;text-align:center;padding:10px 12px;font-size:12px;}\n            .ols-sigma-card-001 .ols-sigma-instruction{top:112px;left:12px;right:12px;text-align:center;font-size:12px;}\n            .ols-sigma-card-001 .ols-sigma-key{left:12px;right:12px;bottom:12px;width:auto;}\n            .ols-sigma-card-001 .ols-sigma-key-row{font-size:12px;white-space:normal;line-height:1.35;}\n            .ols-sigma-card-001 #olsSigmaCompass001{bottom:112px !important;}\n          }\n        <\/style>\n\n        <div class=\"ols-sigma-card\">\n          <div class=\"ols-sigma-header\">\n            <div class=\"ols-sigma-pill\">3D Orbital Model<\/div>\n            <h2 class=\"ols-sigma-title\">\u03c3 Bonding Orbital<\/h2>\n            <p class=\"ols-sigma-subtitle\">A visual model of a sigma (\u03c3) bonding orbital formed by the head-on overlap of two atomic orbitals. Electron density is concentrated along and between the two nuclei.<\/p>\n          <\/div>\n          <div class=\"ols-sigma-viewer-wrap\">\n            <div class=\"ols-sigma-controls\">\n              <button type=\"button\" id=\"olsSigmaToggle001\" class=\"ols-sigma-btn is-active\">Pause Rotation<\/button>\n              <button type=\"button\" id=\"olsSigmaReset001\" class=\"ols-sigma-btn\">Reset View<\/button>\n            <\/div>\n            <canvas id=\"olsSigmaCanvas001\"><\/canvas>\n            <canvas id=\"olsSigmaCompass001\" style=\"position:absolute;bottom:16px;left:16px;width:80px;height:80px;pointer-events:none;z-index:10;\"><\/canvas>\n            <div class=\"ols-sigma-instruction\">Drag to rotate \u2022 Scroll to zoom<\/div>\n            <div class=\"ols-sigma-key\">\n              <div class=\"ols-sigma-key-row\"><div class=\"ols-sigma-key-swatch nuclei\"><\/div><span>Atomic nuclei<\/span><\/div>\n              <div class=\"ols-sigma-key-row\"><div 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window.addEventListener('resize',function(){DPR=Math.min(window.devicePixelRatio||1,1.5);DD=Math.max(1,DPR*0.6);resize();});\n            updBtn();\n          });\n        })();\n        <\/script>\n      <\/section>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">4<\/div><h2>Formation of the Pi Bond<\/h2><\/div>\n        <p>After the sigma bond forms, each carbon retains one <strong>unhybridised p orbital<\/strong> perpendicular to the plane of the molecule.<\/p>\n        <p>The <strong>pi, \u03c0, bond<\/strong> forms when these p orbitals overlap sideways. This produces regions of electron density above and below the line joining the two carbon nuclei.<\/p>\n        <p>Because sideways overlap is less direct than sigma overlap, the pi bond is weaker than the sigma bond. The pi bond also prevents free rotation around the C=C bond.<\/p>\n        <div class=\"ols-definition-box\">\n          <div class=\"ols-definition-circle\">\u03c0<\/div>\n          <p><strong>Pi bond:<\/strong> A covalent bond formed by sideways overlap of p orbitals, with electron density above and below the internuclear axis.<\/p>\n        <\/div>\n        <div class=\"ols-figure-card ols-zoom-pop\">\n          <div class=\"ols-figure-image\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/pi-bond-formation-p-orbital-overlap.png.webp\" role=\"img\" aria-label=\"Sideways overlap of p orbitals forming a pi bond above and below the carbon-carbon bond axis\" style=\"--ols-image: url('https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/pi-bond-formation-p-orbital-overlap.png.webp');\"><\/div>\n          <div class=\"ols-figure-caption\">\n            <h3>Formation of the \u03c0 bond<\/h3>\n            <p>Sideways p-orbital overlap produces electron density above and below the C-C bond axis, restricting rotation and increasing reactivity.<\/p>\n          <\/div>\n        <\/div>\n\n<section class=\"ols-hyb-001\" id=\"olsHyb001\">\n<style>\n@import url('https:\/\/fonts.googleapis.com\/css2?family=Poppins:wght@300;400;500;600&display=swap');\n\n.ols-hyb-001{\n  font-family:'Poppins',system-ui,-apple-system,'Segoe UI',Roboto,Helvetica,Arial,sans-serif;\n  color:#1C244B;\n  background:#ffffff;\n  border:1px solid rgba(28,36,75,0.14);\n  border-radius:28px;\n  box-shadow:0 18px 45px rgba(28,36,75,0.10);\n  padding:44px;\n  margin:26px auto;\n  max-width:980px;\n  box-sizing:border-box;\n  -webkit-font-smoothing:antialiased;\n}\n.ols-hyb-001 *{box-sizing:border-box;}\n\n.ols-hyb-001 .hyb-head{margin:0 0 22px;}\n.ols-hyb-001 h2.hyb-title{\n  font-size:26px; 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color:#aab0c0;\n  font-family:'Poppins',system-ui,-apple-system,'Segoe UI',Roboto,Helvetica,Arial,sans-serif;}\n.ols-hyb-001-cc a{color:#aab0c0; text-decoration:none;}\n.ols-hyb-001-cc a:hover{text-decoration:underline;}\n\n@media (max-width:760px){\n  .ols-hyb-001{padding:26px; border-radius:22px;}\n  .ols-hyb-001 h2.hyb-title{font-size:20.5px;}\n  .ols-hyb-001 p.hyb-sub{font-size:13.5px;}\n  .ols-hyb-001 .hyb-stage{height:420px;}\n  .ols-hyb-001 .hyb-rowlab{min-width:100%;}\n  .ols-hyb-001 .hyb-seg button{padding:9px 15px; font-size:13.5px;}\n  .ols-hyb-001 .hyb-lab{font-size:10.5px; padding:4px 8px;}\n  .ols-hyb-001 .hyb-lab.l-ang{font-size:12px;}\n  .ols-hyb-001 .hyb-info{padding:18px;}\n}\n@media (prefers-reduced-motion:reduce){\n  .ols-hyb-001 .hyb-seg button,.ols-hyb-001 .hyb-pill{transition:none;}\n}\n<\/style>\n\n<div class=\"hyb-head\">\n  <h2 class=\"hyb-title\">Hybridisation of Carbon: sp&sup3;, sp&sup2; and sp Orbitals<\/h2>\n  <p class=\"hyb-sub\">Drag to rotate, scroll or pinch to zoom. Switch between the three states to see how mixing the 2s and 2p orbitals changes the shape around the carbon nucleus, and which 2p orbitals are left unhybridised.<\/p>\n<\/div>\n\n<div class=\"hyb-stage\" id=\"hybStage\">\n  <canvas class=\"hyb-canvas\" id=\"hybCanvas\"><\/canvas>\n  <div class=\"hyb-overlay\" id=\"hybOverlay\"><\/div>\n  <div class=\"hyb-hint\" id=\"hybHint\">Drag to rotate<\/div>\n<\/div>\n\n<div class=\"hyb-controls\">\n  <div class=\"hyb-row\">\n    <span class=\"hyb-rowlab\">Hybridisation<\/span>\n    <div class=\"hyb-seg\" role=\"group\" aria-label=\"Hybridisation state\">\n      <button type=\"button\" data-state=\"sp3\" aria-pressed=\"true\">sp&sup3;<\/button>\n      <button type=\"button\" data-state=\"sp2\" aria-pressed=\"false\">sp&sup2;<\/button>\n      <button type=\"button\" data-state=\"sp\" aria-pressed=\"false\">sp<\/button>\n    <\/div>\n  <\/div>\n\n  <div class=\"hyb-row\">\n    <span class=\"hyb-rowlab\">View<\/span>\n    <div class=\"hyb-seg\" role=\"group\" aria-label=\"Camera view\">\n      <button type=\"button\" data-view=\"front\" aria-pressed=\"false\">Front<\/button>\n      <button type=\"button\" data-view=\"side\" aria-pressed=\"false\">Side<\/button>\n      <button type=\"button\" data-view=\"top\" aria-pressed=\"false\">Top<\/button>\n    <\/div>\n  <\/div>\n\n  <div class=\"hyb-row\">\n    <span class=\"hyb-rowlab\">Show<\/span>\n    <button type=\"button\" class=\"hyb-pill\" id=\"hybTogHyb\" aria-pressed=\"true\"><i class=\"dot\"><\/i>Hybrid orbitals<\/button>\n    <button type=\"button\" class=\"hyb-pill p-orange\" id=\"hybTogP\" aria-pressed=\"true\"><i class=\"dot\"><\/i>p orbitals<\/button>\n    <button type=\"button\" class=\"hyb-pill\" id=\"hybTogLab\" aria-pressed=\"true\"><i class=\"dot\"><\/i>Labels<\/button>\n  <\/div>\n\n  <div class=\"hyb-row\">\n    <span class=\"hyb-rowlab\">Motion<\/span>\n    <button type=\"button\" class=\"hyb-pill\" id=\"hybSpin\" aria-pressed=\"false\"><i class=\"dot\"><\/i>Rotation<\/button>\n    <button type=\"button\" class=\"hyb-pill\" id=\"hybReset\">Reset view<\/button>\n  <\/div>\n<\/div>\n\n<div class=\"hyb-info\">\n  <h3 id=\"hybInfoTitle\">sp&sup3; hybridisation<\/h3>\n  <p id=\"hybInfoText\"><\/p>\n  <div class=\"hyb-facts\">\n    <div class=\"hyb-fact\"><span>Hybrid orbitals<\/span><strong id=\"hybFactN\">4<\/strong><\/div>\n    <div class=\"hyb-fact\"><span>Bond angle<\/span><strong id=\"hybFactA\">109.5&deg;<\/strong><\/div>\n    <div class=\"hyb-fact\"><span>Shape<\/span><strong id=\"hybFactG\">Tetrahedral<\/strong><\/div>\n    <div class=\"hyb-fact\"><span>Unhybridised 2p<\/span><strong id=\"hybFactP\">None<\/strong><\/div>\n    <div class=\"hyb-fact\"><span>Example<\/span><strong id=\"hybFactE\">Methane, CH<sub>4<\/sub><\/strong><\/div>\n  <\/div>\n  <div class=\"hyb-key\">\n    <span><i class=\"k-b\"><\/i>Hybrid orbital<\/span>\n    <span><i class=\"k-o\"><\/i>Unhybridised 2p<\/span>\n    <span><i class=\"k-p\"><\/i>Second unhybridised 2p<\/span>\n    <span><i class=\"k-r\"><\/i>Carbon nucleus<\/span>\n  <\/div>\n<\/div>\n\n<script src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/JS\/hybridisation-carbon.js\"><\/script>\n<\/section>\n<p class=\"ols-hyb-001-cc\">&copy; Dr. Mohammed Al-Fatah &#8211; <a href=\"https:\/\/www.onlinelearningsystem.net\" target=\"_blank\" rel=\"noopener\">onlinelearningsystem.net<\/a><\/p>\n\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Explain the Bond Enthalpy Data<\/h2>\n<p>Write a short explanation, then compare it with the mark points and the model answer.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-10\" class=\"h5p-iframe\" data-content-id=\"10\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Alkene Bonding Explain: Why C=C Is Not Twice as Strong as C-C\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <!-- PI 3D MODEL -->\n      <section class=\"ols-pi-card-001\">\n        <style>\n          .ols-pi-card-001 { width:100%;max-width:1180px;margin:0 auto 34px auto;font-family:Poppins,Arial,sans-serif;box-sizing:border-box; }\n          .ols-pi-card-001 * { box-sizing:border-box; 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Electron density is concentrated in two lobes above and below the internuclear axis. 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Four electrons are concentrated between the two carbon atoms: two in the \u03c3 bond and two in the \u03c0 bond that sits above and below the plane of the molecule.<\/p>\n<p>This exposed, electron-rich region is what makes alkenes reactive. Species that are short of electrons, called <strong>electrophiles<\/strong>, are attracted to the \u03c0 bond and accept a pair of electrons from it. That is the starting point of every electrophilic addition reaction in 3.3.4.2.<\/p>\n<div class=\"ols-table-wrap\">\n<table class=\"ols-table\">\n<thead>\n<tr><th>Feature of the C=C bond<\/th><th>What it means<\/th><th>Consequence<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td><strong>Double covalent bond<\/strong><\/td><td>One \u03c3 bond and one \u03c0 bond between the carbon atoms<\/td><td>Alkenes are unsaturated hydrocarbons<\/td><\/tr>\n<tr><td><strong>Centre of high electron density<\/strong><\/td><td>Four bonding electrons held between two nuclei<\/td><td>Attracts electrophiles such as H\u03b4<sup>+<\/sup> in HBr<\/td><\/tr>\n<tr><td><strong>\u03c0 bond above and below the plane<\/strong><\/td><td>Sideways overlap of p orbitals<\/td><td>Restricted rotation and E-Z isomerism<\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"ols-key-box\">\n<p><strong>Exam sentence:<\/strong> Alkenes are unsaturated hydrocarbons. The C=C double bond is a centre of high electron density, so it attracts electrophiles and undergoes addition reactions.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">6<\/div><h2>Comparing Sigma and Pi Bonds<\/h2><\/div>\n        <p>Exam questions often test whether you can distinguish sigma bonding from pi bonding and connect this bonding to alkene reactivity.<\/p>\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr><th>Feature<\/th><th>Sigma bond<\/th><th>Pi bond<\/th><\/tr>\n            <\/thead>\n            <tbody>\n              <tr><td><strong>How it forms<\/strong><\/td><td>Direct head-on orbital overlap<\/td><td>Sideways overlap of p orbitals<\/td><\/tr>\n              <tr><td><strong>Electron density<\/strong><\/td><td>Between the two nuclei<\/td><td>Above and below the molecular plane<\/td><\/tr>\n              <tr><td><strong>Effect in alkenes<\/strong><\/td><td>Forms the first bond between the carbon atoms<\/td><td>Creates an exposed electron-rich region that reacts with electrophiles<\/td><\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: \u03c3 and \u03c0 Bonds in Propene<\/h2>\n<p>In each round, pick the one statement about propene that is accurate.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-733\" class=\"h5p-iframe\" data-content-id=\"733\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Alkene Bonding Summary: \u03c3 and \u03c0 Bonds in Propene\"><\/iframe><\/div><\/div>\n<\/section>\n\n      \n\n      <section class=\"ols-infographic-full\" aria-label=\"Alkene bonding visual summary\">\n        <div 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<\/style>\r\n\r\n  <div class=\"ols-course-cta-card\">\r\n\r\n    <div class=\"ols-course-cta-top\">\r\n\r\n      <a class=\"ols-course-cta-image-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/alkenes-3-3-4-aqa\/\" aria-label=\"Open the AQA A Level Chemistry 3.3.4 Alkenes course page\">\r\n\r\n        <div class=\"ols-course-cta-image\">\r\n          <img decoding=\"async\"\r\n            src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/aqa-a-level-chemistry-3-3-4-alkenes-interactive-course-banner-v2.jpg\"\r\n            alt=\"AQA A Level Chemistry 3.3.4 Alkenes interactive course banner\"\r\n          >\r\n        <\/div>\r\n\r\n      <\/a>\r\n\r\n      <div class=\"ols-course-cta-content\">\r\n\r\n        <div class=\"ols-course-cta-header-row\">\r\n\r\n          <div class=\"ols-course-cta-kicker\">\r\n            AQA 7405 | 3.3.4 Alkenes Course\r\n          <\/div>\r\n\r\n          <a class=\"ols-course-button ols-course-button-top\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/alkenes-3-3-4-aqa\/\">\r\n            View Course\r\n          <\/a>\r\n\r\n        <\/div>\r\n\r\n        <h2>\r\n          Master Alkenes for AQA A Level Chemistry\r\n        <\/h2>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ols-course-cta-intro-stats\">\r\n\r\n      <p class=\"ols-course-cta-intro\">\r\n        Continue from these free revision notes into the full 3.3.4 Alkenes course. The guided video lessons are ready now; the AQA MCQ bank, teacher-marked short-answer questions and KASP spec-point report are being written, and the course opens for enrolment as soon as they are complete.\r\n      <\/p>\r\n\r\n      <div class=\"ols-course-cta-stats\">\r\n\r\n        <div class=\"ols-course-stat\">\r\n          <span>Recorded lessons<\/span>\n          <strong>Coming soon<\/strong>\r\n        <\/div>\r\n\r\n        <div class=\"ols-course-stat\">\r\n          <span>Video lessons<\/span>\n          <strong>Coming soon<\/strong>\r\n        <\/div>\r\n\r\n        <div class=\"ols-course-stat\">\r\n          <span>MCQ practice<\/span>\n          <strong>Coming soon<\/strong>\r\n        <\/div>\r\n\r\n        <div class=\"ols-course-stat\">\r\n          <span>SAQ practice<\/span>\n          <strong>Coming soon<\/strong>\r\n        <\/div>\r\n\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ols-course-cta-features\">\r\n\r\n      <div class=\"ols-course-feature\">\r\n        <h3>Guided video teaching<\/h3>\r\n        <p>\r\n          Learn the chemistry and exam technique through structured video lessons with worked examples and walkthroughs.\r\n        <\/p>\r\n      <\/div>\r\n\r\n      <div class=\"ols-course-feature\">\r\n        <h3>Instant MCQ feedback<\/h3>\r\n        <p>\r\n          Auto-marked MCQ quizzes provide immediate diagnostic feedback for every answer choice.\r\n        <\/p>\r\n      <\/div>\r\n\r\n      <div class=\"ols-course-feature\">\r\n        <h3>Teacher-marked SAQs<\/h3>\r\n        <p>\r\n          Submit written exam responses and receive chemistry specialist feedback with improvement guidance.\r\n        <\/p>\r\n      <\/div>\r\n\r\n      <div class=\"ols-course-feature\">\r\n        <h3>Progress tracking<\/h3>\r\n        <p>\r\n          Identify strengths and weaknesses across the full 3.3.4 specification with targeted reporting.\r\n        <\/p>\r\n      <\/div>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ols-course-animation-wrap\">\r\n\r\n      <h3 class=\"ols-course-animation-title\">\r\n        See how the course works\r\n      <\/h3>\r\n\r\n      <div class=\"ols-animation-frame-shell\">\r\n        <iframe\r\n          id=\"olsCourseAnimationFrame001\"\r\n          title=\"OLS course preview animation\"\r\n          loading=\"lazy\"\r\n          referrerpolicy=\"no-referrer\">\r\n        <\/iframe>\r\n\r\n        <button\r\n          class=\"ols-animation-start-overlay\"\r\n          id=\"olsCourseAnimationStart001\"\r\n          type=\"button\"\r\n          aria-label=\"Play OLS course preview animation\">\r\n          <span class=\"ols-animation-start-content\">\r\n            <span class=\"ols-animation-play-circle\" aria-hidden=\"true\">\r\n              <span class=\"ols-animation-play-icon\"><\/span>\r\n            <\/span>\r\n            <span class=\"ols-animation-start-text\">\r\n              Play course preview animation\r\n            <\/span>\r\n          <\/span>\r\n        <\/button>\r\n\r\n        <button\r\n          class=\"ols-animation-pause-button\"\r\n          id=\"olsCourseAnimationPause001\"\r\n          type=\"button\"\r\n          aria-label=\"Pause course preview animation\">\r\n          Pause\r\n        <\/button>\r\n      <\/div>\r\n\r\n      <p class=\"ols-course-video-status\">\r\n        Click play to start the course preview animation.\r\n      <\/p>\r\n\r\n    <\/div>\r\n\r\n    <div class=\"ols-course-cta-bottom\">\r\n\r\n      <a class=\"ols-course-button\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/alkenes-3-3-4-aqa\/\">\r\n        View Alkenes 3.3.4 Course\r\n      <\/a>\r\n\r\n    <\/div>\r\n\r\n  <\/div>\r\n\r\n  <template id=\"olsCourseAnimationTemplate001\">\r\n<!DOCTYPE html>\r\n<html lang=\"en\">\r\n<head>\r\n<meta charset=\"UTF-8\">\r\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">\r\n<title>OLS Combined Promo Animation<\/title>\r\n\r\n<style>\r\n*{box-sizing:border-box;}\r\n\r\nhtml.ols-animation-paused *,\r\nhtml.ols-animation-paused *::before,\r\nhtml.ols-animation-paused *::after{\r\n  animation-play-state:paused!important;\r\n}\r\n\r\n:root{\r\n  --ols-video-screen-w:1180;\r\n  --ols-video-screen-h:664;\r\n  --ols-video-screen-scale:1;\r\n  --ols-mcq-screen-w:1360;\r\n  --ols-mcq-screen-h:1130;\r\n  --ols-mcq-screen-scale:1;\r\n  --ols-saq-screen-w:1360;\r\n  --ols-saq-screen-h:965;\r\n  --ols-saq-screen-scale:1;\r\n}\r\n\r\nhtml,\r\nbody{\r\n  width:100%;\r\n  height:100%;\r\n}\r\n\r\nbody{\r\n  margin:0;\r\n  overflow:hidden;\r\n  font-family:Poppins,Arial,sans-serif;\r\n  background:#e9efff;\r\n}\r\n\r\n.ols-combined-stage{\r\n  position:relative;\r\n  width:100vw;\r\n  height:100vh;\r\n  overflow:hidden;\r\n  background:\r\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\r\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\r\n}\r\n\r\n.ols-scene{\r\n  position:absolute;\r\n  inset:0;\r\n  width:100vw;\r\n  height:100vh;\r\n  opacity:0;\r\n  visibility:hidden;\r\n  pointer-events:none;\r\n}\r\n\r\n.ols-scene.active{\r\n  opacity:1;\r\n  visibility:visible;\r\n  pointer-events:auto;\r\n}\r\n\r\n.ols-scene.fade-out{\r\n  animation:olsSceneFadeOut 0.85s ease forwards;\r\n}\r\n\r\n@keyframes olsSceneFadeOut{\r\n  to{\r\n    opacity:0;\r\n    visibility:hidden;\r\n  }\r\n}\r\n\r\n.ols-title-cursor{\r\n  display:inline-block;\r\n  width:5px;\r\n  height:0.85em;\r\n  background:#1C244B;\r\n  margin-left:8px;\r\n  transform:translateY(8px);\r\n  animation:olsBlink 0.8s infinite;\r\n}\r\n\r\n.cursor{\r\n  display:inline-block;\r\n  width:3px;\r\n  height:28px;\r\n  background:#1c244b;\r\n  margin-left:3px;\r\n  transform:translateY(5px);\r\n  animation:olsBlink 0.8s infinite;\r\n}\r\n\r\n@keyframes olsBlink{\r\n  0%,45%{opacity:1;}\r\n  46%,100%{opacity:0;}\r\n}\r\n\r\n.ols-video-stage,\r\n.ols-mcq-stage,\r\n.ols-saq-stage{\r\n  width:100vw;\r\n  height:100vh;\r\n  display:flex;\r\n  justify-content:center;\r\n  align-items:center;\r\n  padding:0;\r\n  overflow:hidden;\r\n  background:\r\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\r\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\r\n}\r\n\r\n.ols-video-title-screen,\r\n.ols-mcq-intro-screen,\r\n.ols-saq-intro{\r\n  position:absolute;\r\n  inset:0;\r\n  z-index:50;\r\n  display:flex;\r\n  justify-content:center;\r\n  align-items:center;\r\n  background:\r\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\r\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\r\n  opacity:1;\r\n  visibility:visible;\r\n  pointer-events:none;\r\n}\r\n\r\n.ols-video-title-screen.hide{animation:olsVideoTitleFadeOut 0.85s ease forwards;}\r\n.ols-mcq-intro-screen.hide{animation:olsMcqIntroFadeOut 0.85s ease forwards;}\r\n.ols-saq-intro.hide{animation:olsSaqIntroFadeOut 0.85s ease forwards;}\r\n\r\n@keyframes olsVideoTitleFadeOut{to{opacity:0;visibility:hidden;}}\r\n@keyframes olsMcqIntroFadeOut{to{opacity:0;visibility:hidden;}}\r\n@keyframes olsSaqIntroFadeOut{to{opacity:0;visibility:hidden;}}\r\n\r\n.ols-video-title-wrap,\r\n.ols-mcq-intro-title-wrap,\r\n.ols-saq-intro-title-wrap{\r\n  max-width:1250px;\r\n  padding:0 34px;\r\n  text-align:center;\r\n}\r\n\r\n.ols-video-title,\r\n.ols-mcq-intro-title,\r\n.ols-saq-intro-title{\r\n  margin:0;\r\n  font-family:Poppins,Arial,sans-serif;\r\n  font-size:clamp(52px,8vw,124px);\r\n  font-weight:600;\r\n  line-height:1.08;\r\n  color:#1C244B;\r\n  text-shadow:-9px 0 9px rgba(28,36,75,0.16);\r\n  letter-spacing:-0.045em;\r\n}\r\n\r\n#videoTitleText,\r\n#mcqIntroTitleText,\r\n#saqIntroTitleText{\r\n  white-space:pre-wrap;\r\n}\r\n\r\n.ols-video-scene{\r\n  width:100%;\r\n  height:100%;\r\n  display:flex;\r\n  justify-content:center;\r\n  align-items:center;\r\n  opacity:0;\r\n  visibility:hidden;\r\n}\r\n\r\n.ols-video-scene.show{\r\n  visibility:visible;\r\n  animation:olsVideoSceneIn 1s ease forwards;\r\n}\r\n\r\n@keyframes olsVideoSceneIn{to{opacity:1;}}\r\n\r\n.ols-video-scale-wrap{\r\n  width:calc(var(--ols-video-screen-w) * 1px);\r\n  height:calc(var(--ols-video-screen-h) * 1px);\r\n  transform:scale(var(--ols-video-screen-scale));\r\n  transform-origin:center center;\r\n  display:flex;\r\n  justify-content:center;\r\n  align-items:center;\r\n}\r\n\r\n.ols-video-card{\r\n  width:1180px;\r\n  height:664px;\r\n  border-radius:28px;\r\n  overflow:hidden;\r\n  background:#1C244B;\r\n  box-shadow:0 28px 80px rgba(28,36,75,0.28);\r\n  transform:translateY(24px) scale(0.96);\r\n  opacity:0;\r\n}\r\n\r\n.ols-video-scene.show .ols-video-card{\r\n  animation:olsVideoCardIn 1s cubic-bezier(.18,.89,.32,1.12) forwards;\r\n  animation-delay:0.2s;\r\n}\r\n\r\n@keyframes olsVideoCardIn{\r\n  to{\r\n    transform:translateY(0) scale(1);\r\n    opacity:1;\r\n  }\r\n}\r\n\r\n.ols-video-card video{\r\n  display:block;\r\n  width:100%;\r\n  height:100%;\r\n  aspect-ratio:16 \/ 9;\r\n  object-fit:cover;\r\n  border:0;\r\n}\r\n\r\n.ols-mcq-scale-wrap,\r\n.ols-saq-scale-wrap{\r\n  width:calc(var(--ols-mcq-screen-w) * 1px);\r\n  height:calc(var(--ols-mcq-screen-h) * 1px);\r\n  transform:scale(var(--ols-mcq-screen-scale));\r\n  transform-origin:center center;\r\n  display:flex;\r\n  justify-content:center;\r\n  align-items:flex-start;\r\n}\r\n\r\n.ols-saq-scale-wrap{\r\n  width:calc(var(--ols-saq-screen-w) * 1px);\r\n  height:calc(var(--ols-saq-screen-h) * 1px);\r\n  transform:scale(var(--ols-saq-screen-scale));\r\n}\r\n\r\n.ols-mcq-screen{\r\n  width:1360px;\r\n  height:1130px;\r\n  border-radius:22px;\r\n  overflow:hidden;\r\n  background:#eaf0ff;\r\n  box-shadow:0 26px 70px rgba(28,36,75,0.22);\r\n  opacity:0;\r\n  transform:translateY(24px) scale(0.96);\r\n}\r\n\r\n.ols-mcq-screen.show{\r\n  animation:olsMcqScreenEnter 1s ease forwards;\r\n}\r\n\r\n@keyframes olsMcqScreenEnter{\r\n  from{opacity:0;transform:translateY(24px) scale(0.96);}\r\n  to{opacity:1;transform:translateY(0) scale(1);}\r\n}\r\n\r\n.mcq-question-area{\r\n  background:#eaf0ff;\r\n  padding:28px 30px 30px;\r\n  position:relative;\r\n  height:610px;\r\n}\r\n\r\n.mcq-question-lead{\r\n  margin:0 0 14px;\r\n  font-size:24px;\r\n  line-height:1.35;\r\n  color:#111827;\r\n}\r\n\r\n.mcq-ionic-table{\r\n  border-collapse:collapse;\r\n  width:500px;\r\n  margin-bottom:8px;\r\n  font-size:21px;\r\n  color:#111827;\r\n}\r\n\r\n.mcq-ionic-table th,\r\n.mcq-ionic-table td{\r\n  border:1.5px solid #c9ced8;\r\n  padding:12px 18px;\r\n  text-align:center;\r\n}\r\n\r\n.mcq-ionic-table th{\r\n  background:#f2f2f2;\r\n  font-weight:700;\r\n}\r\n\r\n.mcq-ionic-table td{\r\n  background:#eaf0ff;\r\n}\r\n\r\n.mcq-question-main{\r\n  margin:6px 0 28px;\r\n  font-size:24px;\r\n  line-height:1.35;\r\n  color:#111827;\r\n}\r\n\r\n.mcq-options-wrap{\r\n  display:flex;\r\n  flex-direction:column;\r\n  gap:17px;\r\n  max-width:1200px;\r\n}\r\n\r\n.mcq-option-row{\r\n  display:flex;\r\n  align-items:center;\r\n  min-height:34px;\r\n  position:relative;\r\n}\r\n\r\n.mcq-radio{\r\n  width:28px;\r\n  height:28px;\r\n  border-radius:50%;\r\n  border:2px solid #6b7280;\r\n  margin-right:16px;\r\n  background:transparent;\r\n  position:relative;\r\n  flex:0 0 auto;\r\n}\r\n\r\n.mcq-radio::after{\r\n  content:\"\";\r\n  position:absolute;\r\n  inset:5px;\r\n  border-radius:50%;\r\n  background:#6b7280;\r\n  opacity:0;\r\n  transform:scale(0.4);\r\n  transition:opacity 0.25s ease,transform 0.25s ease;\r\n}\r\n\r\n.mcq-option-row.selected .mcq-radio::after{\r\n  opacity:1;\r\n  transform:scale(1);\r\n}\r\n\r\n.mcq-radio-ripple{\r\n  position:absolute;\r\n  left:14px;\r\n  top:50%;\r\n  width:28px;\r\n  height:28px;\r\n  border-radius:50%;\r\n  border:2px solid rgba(28,36,75,0.28);\r\n  transform:translate(-50%,-50%) scale(1);\r\n  opacity:0;\r\n  pointer-events:none;\r\n}\r\n\r\n.mcq-option-row.clicking .mcq-radio-ripple{\r\n  animation:mcqRipple 0.75s ease forwards;\r\n}\r\n\r\n@keyframes mcqRipple{\r\n  0%{opacity:0.65;transform:translate(-50%,-50%) scale(1);}\r\n  100%{opacity:0;transform:translate(-50%,-50%) scale(2.5);}\r\n}\r\n\r\n.mcq-option-label{\r\n  font-size:23px;\r\n  color:#111827;\r\n}\r\n\r\n.mcq-specific-feedback{\r\n  display:inline-flex;\r\n  align-items:center;\r\n  margin-left:18px;\r\n  min-height:38px;\r\n  opacity:0;\r\n  transform:translateX(-8px);\r\n}\r\n\r\n.mcq-specific-feedback.show{\r\n  opacity:1;\r\n  transform:translateX(0);\r\n  transition:opacity 0.35s ease,transform 0.35s ease;\r\n}\r\n\r\n.mcq-cross-icon{\r\n  width:26px;\r\n  height:26px;\r\n  border-radius:50%;\r\n  border:2px solid #d83255;\r\n  color:#d83255;\r\n  display:inline-flex;\r\n  justify-content:center;\r\n  align-items:center;\r\n  font-size:18px;\r\n  font-weight:700;\r\n  margin-right:12px;\r\n  opacity:0;\r\n  transform:scale(0.4);\r\n}\r\n\r\n.mcq-cross-icon.show{\r\n  animation:mcqCrossPop 0.35s ease forwards;\r\n}\r\n\r\n@keyframes mcqCrossPop{\r\n  70%{opacity:1;transform:scale(1.18);}\r\n  100%{opacity:1;transform:scale(1);}\r\n}\r\n\r\n.mcq-specific-feedback-text{\r\n  display:inline-block;\r\n  background:#fff4b8;\r\n  color:#111827;\r\n  padding:8px 16px;\r\n  font-size:22px;\r\n  line-height:1.35;\r\n  min-width:850px;\r\n  min-height:44px;\r\n}\r\n\r\n.mcq-submit-button{\r\n  position:absolute;\r\n  right:34px;\r\n  bottom:30px;\r\n  border:0;\r\n  border-radius:999px;\r\n  background:#1C244B;\r\n  color:#ffffff;\r\n  padding:14px 28px;\r\n  font-size:18px;\r\n  font-weight:600;\r\n  box-shadow:0 14px 32px rgba(28,36,75,0.25);\r\n  cursor:default;\r\n  transition:transform 0.2s ease,box-shadow 0.2s ease,background 0.2s ease;\r\n}\r\n\r\n.mcq-submit-button.clicked{\r\n  transform:translateY(2px) scale(0.97);\r\n  background:#26315f;\r\n  box-shadow:0 7px 18px rgba(28,36,75,0.22);\r\n}\r\n\r\n.mcq-general-feedback{\r\n  height:520px;\r\n  background:#fff3c9;\r\n  color:#8a6a00;\r\n  padding:26px 30px 28px;\r\n  font-size:23px;\r\n  line-height:1.34;\r\n  opacity:0;\r\n  transform:translateY(20px);\r\n  transition:opacity 0.7s ease,transform 0.7s ease;\r\n  overflow:hidden;\r\n}\r\n\r\n.mcq-general-feedback.show{\r\n  opacity:1;\r\n  transform:translateY(0);\r\n}\r\n\r\n#mcqGeneralText{\r\n  white-space:pre-wrap;\r\n}\r\n\r\n.mcq-specific-cursor{background:#111827;}\r\n.mcq-general-cursor{background:#8a6a00;}\r\n\r\n.ols-saq-screen{\r\n  width:1360px;\r\n  height:965px;\r\n  border-radius:22px;\r\n  overflow:hidden;\r\n  background:#eaf0ff;\r\n  box-shadow:0 26px 70px rgba(28,36,75,0.22);\r\n  opacity:0;\r\n  transform:translateY(24px) scale(0.96);\r\n}\r\n\r\n.ols-saq-screen.show{\r\n  animation:olsSaqScreenEnter 1s ease forwards;\r\n}\r\n\r\n@keyframes olsSaqScreenEnter{\r\n  from{opacity:0;transform:translateY(24px) scale(0.96);}\r\n  to{opacity:1;transform:translateY(0) scale(1);}\r\n}\r\n\r\n.saq-question-area{\r\n  height:335px;\r\n  background:#eaf0ff;\r\n  padding:30px 40px 32px;\r\n}\r\n\r\n.saq-question-text{\r\n  font-size:25px;\r\n  line-height:1.42;\r\n  color:#111827;\r\n  margin-bottom:22px;\r\n}\r\n\r\n.saq-student-box{\r\n  height:195px;\r\n  background:#f3f4f6;\r\n  border:2px solid #cfd6e3;\r\n  border-radius:8px;\r\n  padding:23px 26px;\r\n  font-size:24px;\r\n  line-height:1.55;\r\n  color:#4b5563;\r\n  position:relative;\r\n  overflow:hidden;\r\n}\r\n\r\n.saq-teacher-feedback{\r\n  height:630px;\r\n  background:#dff3e6;\r\n  color:#075f3b;\r\n  padding:28px 40px 30px;\r\n  font-size:23px;\r\n  line-height:1.47;\r\n  opacity:0;\r\n  transform:translateY(20px);\r\n  transition:opacity 0.7s ease,transform 0.7s ease;\r\n  overflow:hidden;\r\n}\r\n\r\n.saq-teacher-feedback.show{\r\n  opacity:1;\r\n  transform:translateY(0);\r\n}\r\n\r\n#saqTeacherText{\r\n  white-space:pre-wrap;\r\n}\r\n\r\n.saq-teacher-cursor{\r\n  background:#075f3b;\r\n}\r\n\r\n@media(max-width:900px){\r\n  .ols-video-title,\r\n  .ols-mcq-intro-title,\r\n  .ols-saq-intro-title{\r\n    font-size:clamp(42px,11vw,78px);\r\n    line-height:1.12;\r\n  }\r\n\r\n  .ols-title-cursor{\r\n    width:4px;\r\n    margin-left:6px;\r\n  }\r\n\r\n  .ols-video-card{\r\n    border-radius:20px;\r\n  }\r\n}\r\n<\/style>\r\n<\/head>\r\n\r\n<body>\r\n<div class=\"ols-combined-stage\">\r\n\r\n  <section id=\"sceneVideo\" class=\"ols-scene active\">\r\n    <div class=\"ols-video-stage\">\r\n      <div id=\"videoTitleScreen\" class=\"ols-video-title-screen\">\r\n        <div class=\"ols-video-title-wrap\">\r\n          <h1 class=\"ols-video-title\">\r\n            <span id=\"videoTitleText\"><\/span><span id=\"videoTitleCursor\" class=\"ols-title-cursor\"><\/span>\r\n          <\/h1>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <section id=\"videoScene\" class=\"ols-video-scene\">\r\n        <div class=\"ols-video-scale-wrap\">\r\n          <div class=\"ols-video-card\">\r\n            <video\r\n              id=\"lessonVideo\"\r\n              src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Virtual-Lesson.mp4\"\r\n              muted\r\n              playsinline\r\n              preload=\"auto\">\r\n            <\/video>\r\n          <\/div>\r\n        <\/div>\r\n      <\/section>\r\n    <\/div>\r\n  <\/section>\r\n\r\n  <section id=\"sceneMcq\" class=\"ols-scene\">\r\n    <div class=\"ols-mcq-stage\">\r\n      <div id=\"mcqIntroScreen\" class=\"ols-mcq-intro-screen\">\r\n        <div class=\"ols-mcq-intro-title-wrap\">\r\n          <h1 class=\"ols-mcq-intro-title\">\r\n            <span id=\"mcqIntroTitleText\"><\/span><span id=\"mcqIntroTitleCursor\" class=\"ols-title-cursor\"><\/span>\r\n          <\/h1>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ols-mcq-scale-wrap\">\r\n        <main id=\"mcqScreen\" class=\"ols-mcq-screen\">\r\n          <section class=\"mcq-question-area\">\r\n            <p class=\"mcq-question-lead\">Some ionic radii are shown.<\/p>\r\n\r\n            <table class=\"mcq-ionic-table\">\r\n              <thead>\r\n                <tr>\r\n                  <th>Ion<\/th>\r\n                  <th>Ionic radius \/ nm<\/th>\r\n                <\/tr>\r\n              <\/thead>\r\n              <tbody>\r\n                <tr><td>Na<sup>+<\/sup><\/td><td>0.102<\/td><\/tr>\r\n                <tr><td>K<sup>+<\/sup><\/td><td>0.138<\/td><\/tr>\r\n                <tr><td>F<sup>\u2212<\/sup><\/td><td>0.133<\/td><\/tr>\r\n                <tr><td>Cl<sup>\u2212<\/sup><\/td><td>0.180<\/td><\/tr>\r\n              <\/tbody>\r\n            <\/table>\r\n\r\n            <p class=\"mcq-question-main\">Which compound has the strongest ionic bonding?<\/p>\r\n\r\n            <div class=\"mcq-options-wrap\">\r\n              <div id=\"mcqWrongOption\" class=\"mcq-option-row\">\r\n                <span class=\"mcq-radio\"><\/span>\r\n                <span class=\"mcq-radio-ripple\"><\/span>\r\n                <span class=\"mcq-option-label\">sodium chloride<\/span>\r\n\r\n                <span id=\"mcqSpecificFeedback\" class=\"mcq-specific-feedback\">\r\n                  <span id=\"mcqCrossIcon\" class=\"mcq-cross-icon\">\u00d7<\/span>\r\n                  <span class=\"mcq-specific-feedback-text\">\r\n                    <span id=\"mcqSpecificText\"><\/span><span id=\"mcqSpecificCursor\" class=\"cursor mcq-specific-cursor\" style=\"display:none;\"><\/span>\r\n                  <\/span>\r\n                <\/span>\r\n              <\/div>\r\n\r\n              <div class=\"mcq-option-row\"><span class=\"mcq-radio\"><\/span><span class=\"mcq-radio-ripple\"><\/span><span class=\"mcq-option-label\">potassium chloride<\/span><\/div>\r\n              <div class=\"mcq-option-row\"><span class=\"mcq-radio\"><\/span><span class=\"mcq-radio-ripple\"><\/span><span class=\"mcq-option-label\">sodium fluoride<\/span><\/div>\r\n              <div class=\"mcq-option-row\"><span class=\"mcq-radio\"><\/span><span class=\"mcq-radio-ripple\"><\/span><span class=\"mcq-option-label\">potassium fluoride<\/span><\/div>\r\n            <\/div>\r\n\r\n            <button id=\"mcqSubmitButton\" class=\"mcq-submit-button\">Submit answer<\/button>\r\n          <\/section>\r\n\r\n          <section id=\"mcqGeneralFeedback\" class=\"mcq-general-feedback\">\r\n            <span id=\"mcqGeneralText\"><\/span><span id=\"mcqGeneralCursor\" class=\"cursor mcq-general-cursor\" style=\"display:none;\"><\/span>\r\n          <\/section>\r\n        <\/main>\r\n      <\/div>\r\n    <\/div>\r\n  <\/section>\r\n\r\n  <section id=\"sceneSaq\" class=\"ols-scene\">\r\n    <div class=\"ols-saq-stage\">\r\n      <div id=\"saqIntro\" class=\"ols-saq-intro\">\r\n        <div 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the ions can get closer together.\\n\"+\r\n\"\u2022 Smaller ions \u2192 stronger electrostatic attraction \u2192 stronger ionic lattice.\\n\"+\r\n\"\u2022 Na\u207a (0.102 nm) is smaller than K\u207a (0.138 nm).\\n\"+\r\n\"\u2022 F\u207b (0.133 nm) is smaller than Cl\u207b (0.180 nm).\\n\\n\"+\r\n\"Therefore, the strongest ionic bonding occurs in the compound formed by the smallest cation and the smallest anion \u2192 sodium fluoride (NaF).\\n\\n\"+\r\n\"The correct answer is: sodium fluoride\";\r\n\r\nconst mcqIntroScreen=document.getElementById(\"mcqIntroScreen\");\r\nconst mcqIntroTitleText=document.getElementById(\"mcqIntroTitleText\");\r\nconst mcqIntroTitleCursor=document.getElementById(\"mcqIntroTitleCursor\");\r\nconst mcqScreen=document.getElementById(\"mcqScreen\");\r\nconst mcqWrongOption=document.getElementById(\"mcqWrongOption\");\r\nconst mcqSubmitButton=document.getElementById(\"mcqSubmitButton\");\r\nconst 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Melting temperature is a result of bonding strength, not the cause of it.\\n\\n\"+\r\n\"In metallic bonding, positive metal ions are attracted to a sea of delocalised electrons. The strength of this attraction depends on the charge of the ions and the number of delocalised electrons.\\n\\n\"+\r\n\"Magnesium forms Mg\u00b2\u207a ions and contributes two delocalised electrons per atom, whereas sodium forms Na\u207a ions and contributes only one electron. This results in a stronger electrostatic attraction in magnesium. Additionally, Mg\u00b2\u207a ions have a higher charge density than Na\u207a ions, further strengthening the metallic bonding.\\n\\n\"+\r\n\"Next time, include:\\n\"+\r\n\"\u2022 Ion charge: magnesium forms Mg\u00b2\u207a, sodium forms Na\u207a \u2713\\n\"+\r\n\"\u2022 Delocalised electrons: magnesium provides more electrons to the sea \u2713\\n\"+\r\n\"\u2022 Charge density: smaller, more highly charged ions create stronger attraction \u2713\\n\\n\"+\r\n\"You were close. 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