{"id":7543,"date":"2026-09-11T17:48:58","date_gmt":"2026-09-11T16:48:58","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/alkanes-and-sp3-carbon\/"},"modified":"2026-09-22T12:58:40","modified_gmt":"2026-09-22T11:58:40","slug":"alkanes-and-sp3-carbon","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/alkanes-and-sp3-carbon\/","title":{"rendered":"Alkanes and sp3 Carbon"},"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-free-radical-substitution-page\">\n  <style>\n    .ols-revision-page {\n      --navy: #1C244B;\n      --blue: #2563eb;\n      --soft-blue: #eef4ff;\n      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text-align: center; line-height: 1.6; }\n    .ols-figure-placeholder .ols-figure-image { background: transparent; }\n    .ols-figure-placeholder { background: #ffffff; border: 1px solid rgba(28, 36, 75, 0.12); border-radius: 22px; padding: 14px; margin: 18px 0 6px; }\n    .ols-figure-placeholder .ols-figure-caption p { margin: 10px 0 0; font-size: 14px; color: #667085; text-align: center; }\n<\/style>\n\n  <aside class=\"ols-sidebar\">\n  <div class=\"ols-sidebar-header\">\n    <h3>Revision Notes<\/h3>\n    <p>Cambridge International AS Level Chemistry<\/p>\n  <\/div>\n  <div class=\"ols-topic-group\">\n    <h4>13.3 Shapes of Organic Molecules<\/h4>\n    <ul class=\"ols-topic-list\">\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/\">Part overview<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/alkene-bonding\/\">Alkene Bonding<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/alkanes-and-sp3-carbon\/\">Alkanes and sp3 Carbon<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/alkynes-and-nitriles-sp-carbon\/\">Alkynes and Nitriles: sp Carbon<\/a><\/li>\n    <\/ul>\n  <\/div>\n  <div class=\"ols-topic-group\">\n    <h4>Other Topic 13 Parts<\/h4>\n    <ul class=\"ols-topic-list\">\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/\">Topic 13 overview<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/formulas-functional-groups-and-naming\/\">13.1 Formulas, Functional Groups and Naming<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/characteristic-organic-reactions\/\">13.2 Characteristic Organic Reactions<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/isomerism\/\">13.4 Isomerism<\/a><\/li>\n      <li><a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-14-hydrocarbons\/\">Topic 14 Hydrocarbons<\/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      .toLowerCase();\r\n  }\r\n\r\n  function highlightActive() {\r\n    var sidebar = document.querySelector('.ols-sidebar');\r\n    if (!sidebar) return false;\r\n\r\n    var currentPath = normalisePath(window.location.pathname);\r\n    var links = sidebar.querySelectorAll('a[href]');\r\n    var matched = null;\r\n    var matchedLength = 0;\r\n\r\n    sidebar.querySelectorAll('.active, .active-main, .parent-active').forEach(function(item) {\r\n      item.classList.remove('active', 'active-main', 'parent-active');\r\n    });\r\n\r\n    sidebar.querySelectorAll('a[data-ols-disabled-parent=\"1\"], 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href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/\">Shapes of Organic Molecules<\/a> \/\n<span>Alkanes and sp3 Carbon<\/span>\n<\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Alkanes and sp3 Carbon<\/h1>\n        <p class=\"ols-page-intro\">A concise Cambridge International AS Level Chemistry revision guide to sp3 hybridised carbon (13.3.2 and 13.3.3): how the four sp3 orbitals form, the tetrahedral shape and 109.5\u00b0 bond angle, the \u03c3 bonds of alkanes with free rotation, and straight-chain, branched and cyclic molecules (13.3.1).<\/p>\n\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">AS Level<\/div>\n<div class=\"ols-badge\">Topic 13: An Introduction to AS Level Organic Chemistry<\/div>\n<div class=\"ols-badge\">9701 Papers 1 and 2<\/div>\n        <\/div>\n\n        <div class=\"ols-author\">\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            <h2 class=\"ols-author-title\">Written by: Dr. Mohammed Al-Fatah<\/h2>\n            <p class=\"ols-author-description\">Chemistry specialist revision notes for A Level Chemistry.<\/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          <\/div>\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: The Alkane Family and Shared Pairs<\/h2>\n<p>Before you start, check the alkane general formula, what saturated means and what a single covalent bond is.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"832\"><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">1<\/div>\n<h2>Why Carbon Hybridises<\/h2>\n<\/div>\n<p>A carbon atom has the electron configuration 1s<sup>2<\/sup> 2s<sup>2<\/sup> 2p<sup>2<\/sup>, which suggests only two unpaired electrons and two bonds. In practice carbon always forms four bonds. Cambridge explains this using <strong>hybridisation<\/strong>: the 2s orbital and the three 2p orbitals mix to form new orbitals of equal energy, each holding one electron. In an alkane all four are mixed, giving four <strong>sp<sup>3<\/sup> hybrid orbitals<\/strong>.<\/p>\n<div class=\"ols-table-wrap\">\n<table class=\"ols-table\">\n<thead>\n<tr><th>Orbitals mixed<\/th><th>Hybrid orbitals formed<\/th><th>Shape of the set<\/th><th>Bond angle<\/th><th>Found in<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td><strong>One 2s + three 2p<\/strong><\/td><td>Four sp<sup>3<\/sup><\/td><td>Tetrahedral<\/td><td>109.5\u00b0<\/td><td>Alkanes, and any carbon with four single bonds<\/td><\/tr>\n<tr><td><strong>One 2s + two 2p<\/strong><\/td><td>Three sp<sup>2<\/sup> (one p left over)<\/td><td>Trigonal planar<\/td><td>120\u00b0<\/td><td>Alkenes, carbonyl carbon<\/td><\/tr>\n<tr><td><strong>One 2s + one 2p<\/strong><\/td><td>Two sp (two p left over)<\/td><td>Linear<\/td><td>180\u00b0<\/td><td>Alkynes, nitriles<\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<div class=\"ols-figure-card ols-zoom-pop\">\n<div class=\"ols-figure-image\">\n<a class=\"ols-image-fullscreen-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/orbital-diagram-for-sp3-hybridisation.jpg\" target=\"_blank\" rel=\"noopener\" aria-label=\"Open image fullscreen\">\n<img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/orbital-diagram-for-sp3-hybridisation.jpg\" alt=\"One 2s and three 2p orbitals mixing to give four tetrahedral sp3 hybrid orbitals\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/orbital-diagram-for-sp3-hybridisation.jpg\">\n<\/a>\n<\/div>\n<div class=\"ols-figure-caption\"><p>Mixing one 2s and three 2p orbitals gives four sp3 hybrid orbitals pointing to the corners of a tetrahedron.<\/p><\/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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display:flex; gap:26px; flex-wrap:wrap;\n  padding-top:16px; border-top:1px solid rgba(28,36,75,0.10);\n}\n.ols-hyb-001 .hyb-fact{min-width:110px;}\n.ols-hyb-001 .hyb-fact span{display:block; font-size:11.5px; color:#7d8399; font-weight:400; margin-bottom:3px;}\n.ols-hyb-001 .hyb-fact strong{display:block; font-size:15px; font-weight:600; color:#1C244B;}\n\n.ols-hyb-001 .hyb-key{\n  margin-top:16px; display:flex; gap:20px; flex-wrap:wrap;\n  font-size:12.5px; font-weight:400; color:#5a6180;\n}\n.ols-hyb-001 .hyb-key i{\n  display:inline-block; width:13px; height:13px; border-radius:3px;\n  margin-right:7px; vertical-align:-2px; border:1px solid rgba(28,36,75,0.18);\n}\n.ols-hyb-001 .hyb-key .k-b{background:rgba(42,79,196,0.5);}\n.ols-hyb-001 .hyb-key .k-o{background:rgba(197,101,18,0.5);}\n.ols-hyb-001 .hyb-key .k-p{background:rgba(124,58,183,0.5);}\n.ols-hyb-001 .hyb-key .k-r{background:rgba(190,40,40,0.9);}\n\n.ols-hyb-001-cc{margin:14px 0 0; text-align:center; font-size:11px; font-style:italic; 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<div class=\"ols-key-box\">\n<p><strong>Key idea:<\/strong> The number of hybrid orbitals equals the number of atomic orbitals mixed. Four orbitals mixed gives four sp3 orbitals, so the carbon makes four \u03c3 bonds.<\/p>\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: Name the Hybridisation<\/h2>\n<p>Five quick questions on carbon atoms in molecules the page does not use.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-415\" class=\"h5p-iframe\" data-content-id=\"415\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"sp\u00b3 Carbon Quick-Fire: Naming the Hybridisation of a Carbon Atom\"><\/iframe><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">2<\/div>\n<h2>The Tetrahedral Carbon of Alkanes<\/h2>\n<\/div>\n<p>Each sp<sup>3<\/sup> orbital overlaps <strong>head-on<\/strong> with an orbital on another atom to form a <strong>\u03c3 bond<\/strong>: with a 1s orbital of hydrogen for a C-H bond, or with an sp<sup>3<\/sup> orbital of another carbon for a C-C bond. Because the electron density of a \u03c3 bond lies along the line between the nuclei, the two ends can <strong>rotate freely<\/strong> about the bond.<\/p>\n<p>The four \u03c3 bonds repel each other equally and point to the corners of a tetrahedron, so every carbon atom in an alkane is <strong>tetrahedral<\/strong> with bond angles of <strong>109.5\u00b0<\/strong>. In propane, for example, both the end carbons and the middle carbon are tetrahedral, which is why the carbon chain zig-zags rather than lying in a straight line.<\/p>\n<div class=\"ols-figure-card ols-zoom-pop\">\n<div class=\"ols-figure-image\">\n<a class=\"ols-image-fullscreen-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/propane-drawn-in-three-dimensions.jpg\" target=\"_blank\" rel=\"noopener\" aria-label=\"Open image fullscreen\">\n<img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/propane-drawn-in-three-dimensions.jpg\" alt=\"Propane drawn in three dimensions with tetrahedral carbons, 109.5 degree angles and free rotation about the C-C bond\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/propane-drawn-in-three-dimensions.jpg\">\n<\/a>\n<\/div>\n<div class=\"ols-figure-caption\"><p>Every carbon in propane is sp3 hybridised and tetrahedral, and the C-C \u03c3 bonds allow free rotation.<\/p><\/div>\n<\/div>\n<div class=\"ols-key-box\">\n<p><strong>Exam sentence:<\/strong> In an alkane each carbon atom is sp3 hybridised; its four sp3 orbitals form four \u03c3 bonds arranged tetrahedrally with bond angles of 109.5\u00b0, and there is free rotation about each C-C \u03c3 bond.<\/p>\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: Counting Sigma Bonds<\/h2>\n<p>Type a number in each gap; count carbon to carbon and carbon to hydrogen bonds separately.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-416\" class=\"h5p-iframe\" data-content-id=\"416\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"sp\u00b3 Carbon Fill the Blanks: Counting Sigma Bonds and Free Rotations\"><\/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: Two Drawings of Butane<\/h2>\n<p>Decide whether the two drawings show one compound or two, and why.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-417\" class=\"h5p-iframe\" data-content-id=\"417\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"sp\u00b3 Carbon MCQ: Two Drawings of Butane\"><\/iframe><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card purple\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">3<\/div>\n<h2>Straight-Chain, Branched and Cyclic Molecules<\/h2>\n<\/div>\n<p>Cambridge 13.3.1 asks you to describe organic molecules as <strong>straight-chained<\/strong>, <strong>branched<\/strong> or <strong>cyclic<\/strong>. All three are built from sp<sup>3<\/sup> carbons in alkanes; the difference is how the tetrahedral carbons are joined.<\/p>\n<div class=\"ols-table-wrap\">\n<table class=\"ols-table\">\n<thead>\n<tr><th>Description<\/th><th>Meaning<\/th><th>Example<\/th><th>General formula (alkanes)<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td><strong>Straight-chain<\/strong><\/td><td>Every carbon is bonded to at most two other carbons, forming one continuous chain<\/td><td>Hexane<\/td><td>C<sub>n<\/sub>H<sub>2n+2<\/sub><\/td><\/tr>\n<tr><td><strong>Branched<\/strong><\/td><td>At least one carbon is bonded to three or four other carbons, so side chains come off the main chain<\/td><td>2-Methylpentane, 2,2-dimethylbutane<\/td><td>C<sub>n<\/sub>H<sub>2n+2<\/sub><\/td><\/tr>\n<tr><td><strong>Cyclic<\/strong><\/td><td>The carbon atoms form a ring<\/td><td>Cyclohexane<\/td><td>C<sub>n<\/sub>H<sub>2n<\/sub><\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>A &#8220;straight&#8221; chain is not geometrically straight: the tetrahedral angles make it zig-zag. In cyclohexane the ring is not flat either; it puckers into a chair shape so that every carbon keeps its 109.5\u00b0 angles.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Exam focus:<\/strong> Straight-chain and branched isomers share a molecular formula; the cyclic alkane with the same number of carbons has two fewer hydrogen atoms because two C-H bonds are replaced by the extra C-C bond that closes the ring.<\/p>\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: Pick the Accurate Statement<\/h2>\n<p>In each round, choose the one statement that is accurate.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-418\" class=\"h5p-iframe\" data-content-id=\"418\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"sp\u00b3 Carbon Summary: Shapes, Formulae and Sigma Bonds\"><\/iframe><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">4<\/div>\n<h2>Common Exam Mistakes<\/h2>\n<\/div>\n<ul>\n<li>Saying carbon has four sp<sup>3<\/sup> orbitals because it &#8220;needs four bonds&#8221;. Give the mechanism: one 2s and three 2p orbitals mix.<\/li>\n<li>Describing C-C bonds in alkanes as \u03c0 bonds. All bonds in an alkane are \u03c3 bonds.<\/li>\n<li>Drawing the carbon chain as a straight line and quoting 180\u00b0. The chain zig-zags with 109.5\u00b0 angles.<\/li>\n<li>Giving cyclohexane the alkane formula C<sub>6<\/sub>H<sub>14<\/sub>. The ring formula is C<sub>6<\/sub>H<sub>12<\/sub>.<\/li>\n<\/ul>\n<div class=\"ols-key-box\">\n<p><strong>Exam sentence:<\/strong> sp3 carbon: four hybrid orbitals, four \u03c3 bonds, tetrahedral, 109.5\u00b0, free rotation.<\/p>\n<\/div>\n<\/article>\n\n<section class=\"ols-course-cta-alkenes\" id=\"olsCourseCtaAlkenes001\">\r\n  <style>\r\n    .ols-course-cta-alkenes,\r\n    .ols-course-cta-alkenes * {\r\n      box-sizing: border-box;\r\n    }\r\n\r\n    .ols-course-cta-alkenes {\r\n      --navy: #1C244B;\r\n      --blue: #2563eb;\r\n      --body-text: #1f2937;\r\n      --grey-text: #667085;\r\n      --border: rgba(28, 36, 75, 0.14);\r\n      --shadow: 0 18px 45px rgba(28, 36, 75, 0.12);\r\n      --inner-shadow: 0 10px 26px rgba(28, 36, 75, 0.08);\r\n\r\n      width: 100%;\r\n      margin: 30px 0 24px;\r\n      font-family: Poppins, Arial, sans-serif;\r\n    }\r\n\r\n    .ols-course-cta-alkenes .ols-course-cta-card {\r\n      overflow: hidden;\r\n      border-radius: 30px;\r\n      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}\r\n\r\n      .ols-course-cta-alkenes .ols-animation-frame-shell {\r\n        height: 420px;\r\n        border-radius: 18px;\r\n      }\r\n\r\n      .ols-course-cta-alkenes .ols-animation-play-circle {\r\n        width: 76px;\r\n        height: 76px;\r\n      }\r\n\r\n      .ols-course-cta-alkenes .ols-animation-play-icon {\r\n        border-top-width: 14px;\r\n        border-bottom-width: 14px;\r\n        border-left-width: 22px;\r\n      }\r\n\r\n      .ols-course-cta-alkenes .ols-animation-pause-button {\r\n        left: 12px;\r\n        bottom: 12px;\r\n        min-width: 84px;\r\n        padding: 9px 14px;\r\n        font-size: 13px;\r\n      }\r\n\r\n      .ols-course-cta-alkenes .ols-course-button {\r\n        width: 100%;\r\n      }\r\n    }\r\n  <\/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\/introduction-to-organic-chemistry-and-alkanes-topics-13-14-1-cambridge-international\/\" aria-label=\"Open the Cambridge International AS and A Level Chemistry Topics 13 and 14.1 Introduction to Organic Chemistry and Alkanes 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\/cambridge-international-a-level-chemistry-topics-13-14-1-organic-chemistry-alkanes-interactive-course-banner.jpg\"\r\n            alt=\"Cambridge International AS and A Level Chemistry Topics 13 and 14.1 Introduction to Organic Chemistry and Alkanes 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            Cambridge 9701 | Topics 13 and 14.1 Course\r\n          <\/div>\r\n\r\n          <a class=\"ols-course-button ols-course-button-top\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/introduction-to-organic-chemistry-and-alkanes-topics-13-14-1-cambridge-international\/\">\r\n            View Course\r\n          <\/a>\r\n\r\n        <\/div>\r\n\r\n        <h2>\r\n          Master Introduction to Organic Chemistry and Alkanes for Cambridge International AS &amp; 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 Topics 13 and 14.1 Introduction to Organic Chemistry and Alkanes course. The guided video lessons are ready now; the Cambridge International 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 Topics 13 and 14.1 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\/introduction-to-organic-chemistry-and-alkanes-topics-13-14-1-cambridge-international\/\">\r\n        View Introduction to Organic Chemistry and Alkanes 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  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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 class=\"ols-saq-intro-title-wrap\">\r\n          <h1 class=\"ols-saq-intro-title\">\r\n            <span id=\"saqIntroTitleText\"><\/span><span id=\"saqIntroTitleCursor\" class=\"ols-title-cursor\"><\/span>\r\n          <\/h1>\r\n        <\/div>\r\n      <\/div>\r\n\r\n      <div class=\"ols-saq-scale-wrap\">\r\n        <main id=\"saqScreen\" class=\"ols-saq-screen\">\r\n          <section class=\"saq-question-area\">\r\n            <div class=\"saq-question-text\">\r\n              <strong>(ii)<\/strong>&nbsp;&nbsp; Melting temperature depends on the strength of metallic bonding.<br>\r\n              Explain why the metallic bonding in magnesium is much stronger than that in sodium.\r\n            <\/div>\r\n\r\n            <div class=\"saq-student-box\">\r\n              <span id=\"saqStudentText\"><\/span><span id=\"saqStudentCursor\" class=\"cursor\"><\/span>\r\n            <\/div>\r\n          <\/section>\r\n\r\n          <section id=\"saqTeacherFeedback\" 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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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because it has more atoms packed together and melts at a higher temperature than sodium.\";\r\nconst saqTeacherFeedbackText=\r\n\"Comment:\\n\"+\r\n\"This answer is not correct. 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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These bonds require a large amount of energy to break.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>What condition is needed for alkanes to react with chlorine?<\/h3>\n            <p>Ultraviolet light is needed. UV light provides enough energy to break the Cl-Cl bond by homolytic fission, forming chlorine radicals.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>What is a free radical?<\/h3>\n            <p>A free radical is a species with an unpaired electron. The unpaired electron is usually represented using a dot, such as Cl\u2022.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>Why is the reaction called substitution?<\/h3>\n            <p>It is called substitution because a hydrogen atom in the alkane is replaced by a halogen atom.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>Why can a mixture of products form?<\/h3>\n            <p>After the first substitution, the haloalkane product can undergo further substitution. This can replace more hydrogen atoms and produce a mixture of chlorinated products.<\/p>\n          <\/div>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-related-card\">\n        <h2>Related Topics<\/h2>\n        <p>Continue through the alkane reaction sequence by studying each stage of the free-radical substitution mechanism.<\/p>\n\n        <div class=\"ols-related-grid\">\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-14-hydrocarbons\/alkanes\/reactions\/initiation\/\">Initiation<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-14-hydrocarbons\/alkanes\/reactions\/propagation\/\">Propagation<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-14-hydrocarbons\/alkanes\/reactions\/termination\/\">Termination<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-14-hydrocarbons\/alkanes\/reactions\/further-substitution\/\">Further Substitution<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-14-hydrocarbons\/alkanes\/fuel\/combustion\/\">Combustion<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-14-hydrocarbons\/alkenes\/electrophilic-addition-mechanism\/\">Electrophilic Addition Mechanism<\/a>\n        <\/div>\n      <\/section>\n\n      <!-- OLS Author Copyright Footprint \/ Attribution Card -->\n      <section class=\"ols-attribution-card\">\n        <style>\n          .ols-attribution-card {\n            background: linear-gradient(135deg, #ffffff, #f8fbff);\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: 34px;\n            margin-bottom: 24px;\n            overflow: hidden;\n            font-family: Poppins, Arial, sans-serif;\n            box-sizing: border-box;\n          }\n      \n          .ols-attribution-card,\n          .ols-attribution-card * {\n            box-sizing: border-box;\n          }\n      \n          .ols-attribution-card p {\n            margin: 0;\n            font-size: 14px;\n            line-height: 1.65;\n            font-weight: 300;\n            color: #667085;\n          }\n      \n          .ols-attribution-card strong {\n            font-weight: 700;\n            color: #1C244B;\n          }\n      \n          @media (max-width: 760px) {\n            .ols-attribution-card {\n              padding: 24px 18px;\n              border-radius: 22px;\n            }\n          }\n        <\/style>\n      \n        <p><strong>Copyright notice:<\/strong> This OLS revision content, including the explanations, layout, diagrams, tables and embedded learning structure, is authored for Online Learning System by Dr. Mohammed Al-Fatah. It may not be copied, reproduced, redistributed or adapted without written permission.<\/p>\n      <\/section>\n\n      <script type=\"application\/ld+json\">{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@graph\": [\n    {\n      \"@type\": \"WebPage\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/alkanes-and-sp3-carbon\/#webpage\",\n      \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/alkanes-and-sp3-carbon\/\",\n      \"name\": \"Alkanes and sp3 Carbon - Cambridge International AS Level Chemistry\",\n      \"description\": \"Cambridge International AS Level Chemistry 13.3 revision notes: sp3 hybridisation in alkanes, tetrahedral shape and 109.5\u00b0 bond angle, \u03c3 bonds and free rotation, and straight-chain, branched and cyclic organic molecules.\",\n      \"inLanguage\": \"en-GB\",\n      \"isPartOf\": {\n        \"@type\": \"WebSite\",\n        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/#website\",\n        \"name\": \"Online Learning System\",\n        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/\"\n      },\n      \"about\": [\n        {\n          \"@type\": \"Thing\",\n          \"name\": \"Free radical substitution\"\n        },\n        {\n          \"@type\": \"Thing\",\n          \"name\": \"Alkanes\"\n        },\n        {\n          \"@type\": \"Thing\",\n          \"name\": \"Homolytic fission\"\n        }\n      ],\n      \"author\": {\n        \"@type\": \"Person\",\n        \"name\": \"Dr. Mohammed Al-Fatah\"\n      }\n    },\n    {\n      \"@type\": \"BreadcrumbList\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/alkanes-and-sp3-carbon\/#breadcrumb\",\n      \"itemListElement\": [\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 1,\n          \"name\": \"Revision Notes\",\n          \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\"\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 2,\n          \"name\": \"A Level Chemistry\",\n          \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\"\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 3,\n          \"name\": \"Cambridge International (CIE)\",\n          \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/\"\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 4,\n          \"name\": \"Topic 13 Introduction to AS Organic Chemistry\",\n          \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/\"\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 5,\n          \"name\": \"Shapes of Organic Molecules\",\n          \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/\"\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 6,\n          \"name\": \"Alkanes and sp3 Carbon\",\n          \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/cie\/topic-13-an-introduction-to-as-level-organic-chemistry\/shapes-of-organic-molecules\/alkanes-and-sp3-carbon\/\"\n        }\n      ]\n    },\n    {\n      \"@type\": \"Course\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/organic-chemistry-and-alkanes-topic-6ab\/#course\",\n      \"name\": \"Organic Chemistry and Alkanes Topic 14 Cambridge International AS &amp; 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