{"id":7766,"date":"2026-09-13T19:06:17","date_gmt":"2026-09-13T18:06:17","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/structure-types\/"},"modified":"2026-09-13T19:06:17","modified_gmt":"2026-09-13T18:06:17","slug":"structure-types","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/structure-types\/","title":{"rendered":"Structure Types"},"content":{"rendered":"\n<section class=\"ols-revision-page ols-ionic-bonding-structure-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      --soft-orange: #fff7ed;\n      --grey-text: #667085;\n      --body-text: #1f2937;\n      --border: rgba(28, 36, 75, 0.14);\n      --shadow: 0 18px 45px rgba(28, 36, 75, 0.10);\n      --inner-shadow: 0 10px 26px rgba(28, 36, 75, 0.08);\n      font-family: Poppins, Arial, sans-serif;\n      color: var(--navy);\n      background: #ffffff;\n    }\n\n    .ols-revision-page * { box-sizing: border-box; }\n    .ols-main { min-width: 0; max-width: 970px; }\n    .ols-breadcrumbs { display: flex; flex-wrap: wrap; gap: 8px; margin: 10px 0 22px; font-size: 15px; color: var(--grey-text); }\n    .ols-breadcrumbs a, .ols-breadcrumbs span { color: var(--grey-text); text-decoration: none; font-weight: 600; }\n    .ols-breadcrumbs a:hover { color: var(--blue); text-decoration: underline; text-underline-offset: 3px; }\n    .ols-title-card, .ols-note-card, .ols-h5p-card, .ols-related-card, .ols-faq-card { background: #ffffff; border: 1px solid var(--border); border-radius: 28px; box-shadow: var(--shadow); padding: 34px; margin-bottom: 24px; overflow: hidden; }\n    .ols-title-card { background: linear-gradient(135deg, #ffffff 0%, #f8fbff 100%); }\n    .ols-title-card h1 { margin: 0 0 18px; font-size: clamp(36px, 5vw, 58px); line-height: 1.08; font-weight: 800; letter-spacing: -0.04em; color: #111827; }\n    .ols-page-intro { font-size: 19px; line-height: 1.7; font-weight: 300; color: var(--body-text); margin: 0 0 22px; }\n    .ols-badges { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 22px; }\n    .ols-badge { display: inline-flex; align-items: center; padding: 9px 14px; border-radius: 999px; background: #ffffff; border: 1px solid var(--border); font-size: 15px; font-weight: 600; color: var(--navy); }\n    .ols-author { display: flex; align-items: center; gap: 20px; padding: 28px; border-radius: 28px; background: linear-gradient(135deg, #ffffff 0%, #f8fbff 100%); border: 1px solid rgba(28,36,75,0.12); box-shadow: 0 18px 45px rgba(28,36,75,0.10); margin-top: 22px; }\n    .ols-author-avatar-img { width: 92px; height: 92px; border-radius: 50%; object-fit: cover; object-position: center; flex-shrink: 0; border: 4px solid #ffffff; box-shadow: 0 14px 32px rgba(28,36,75,0.18), 0 0 0 1px rgba(28,36,75,0.10); transition: transform 0.25s ease, box-shadow 0.25s ease; }\n    .ols-author:hover .ols-author-avatar-img { transform: scale(1.04); box-shadow: 0 20px 42px rgba(28,36,75,0.22), 0 0 0 1px rgba(28,36,75,0.10); }\n    .ols-author-content { min-width: 0; }\n    .ols-author-title { margin: 0 0 4px; font-size: clamp(24px,3vw,34px); line-height: 1.15; font-weight: 700; color: var(--navy); letter-spacing: -0.03em; }\n    .ols-author-description { margin: 0; font-size: 17px; line-height: 1.7; font-weight: 300; color: var(--grey-text); }\n    .ols-linkedin-pill { display: inline-flex; align-items: center; justify-content: center; gap: 10px; margin-top: 16px; padding: 11px 18px; border-radius: 999px; background: linear-gradient(135deg,#0A66C2,#004182); color: #ffffff; text-decoration: none; font-size: 14px; line-height: 1; font-weight: 700; letter-spacing: 0.01em; box-shadow: 0 10px 22px rgba(10,102,194,0.24); position: relative; overflow: hidden; transition: transform 0.22s ease, box-shadow 0.22s ease; }\n    .ols-linkedin-pill::before { content: \"\"; position: absolute; top: 0; left: -120%; width: 100%; height: 100%; background: linear-gradient(120deg, rgba(255,255,255,0) 0%, rgba(255,255,255,0.28) 50%, rgba(255,255,255,0) 100%); transition: left 0.7s ease; }\n    .ols-linkedin-pill:hover { transform: translateY(-3px) scale(1.03); box-shadow: 0 16px 34px rgba(10,102,194,0.34), 0 0 0 6px rgba(10,102,194,0.10); color: #ffffff; }\n    .ols-linkedin-pill:hover::before { left: 120%; }\n    .ols-linkedin-icon { width: 18px; height: 18px; display: block; flex-shrink: 0; }\n    .ols-note-card.soft { background: linear-gradient(135deg, #ffffff 0%, var(--soft-red) 100%); }\n    .ols-note-card.purple { background: linear-gradient(135deg, #ffffff 0%, var(--soft-purple) 100%); }\n    .ols-note-card.orange { background: linear-gradient(135deg, #ffffff 0%, var(--soft-orange) 100%); }\n    .ols-note-title { display: flex; align-items: center; gap: 14px; margin-bottom: 20px; }\n    .ols-note-icon { width: 52px; height: 52px; border-radius: 16px; background: var(--navy); color: #ffffff; display: grid; place-items: center; font-size: 24px; font-weight: 800; flex-shrink: 0; }\n    .ols-note-title h2, .ols-h5p-card h2, .ols-related-card h2, .ols-faq-card h2 { margin: 0; font-size: clamp(28px, 3.5vw, 42px); line-height: 1.15; font-weight: 800; color: #111827; letter-spacing: -0.03em; }\n    .ols-h5p-card h2, .ols-related-card h2, .ols-faq-card h2 { margin-bottom: 14px; }\n    .ols-note-card p, .ols-note-card li { font-size: clamp(15px, 1.25vw, 17px); line-height: 1.65; font-weight: 300; color: var(--body-text); }\n    .ols-h5p-card p, .ols-related-card p, .ols-faq-card p { font-size: clamp(15px, 1.3vw, 18px); line-height: 1.65; font-weight: 300; color: var(--body-text); }\n    .ols-note-card strong, .ols-h5p-card strong, .ols-related-card strong, .ols-faq-card strong { font-weight: 700; color: var(--navy); }\n    .ols-note-card ul, .ols-note-card ol { margin: 0; padding-left: 22px; }\n    .ols-key-box { margin-top: 20px; background: var(--soft-green); border: 1px solid rgba(63, 143, 70, 0.25); border-radius: 20px; padding: 18px 20px; }\n    .ols-key-box p { margin: 0; font-weight: 400; color: var(--navy); }\n    .ols-rule-list { display: grid; gap: 14px; margin-top: 18px; }\n    .ols-rule-item { background: #ffffff; border: 1px solid var(--border); border-left: 5px solid var(--blue); border-radius: 18px; padding: 18px; box-shadow: var(--inner-shadow); }\n    .ols-rule-item h3 { margin: 0 0 8px; font-size: 20px; line-height: 1.25; color: var(--navy); }\n    .ols-rule-item p { margin: 0; font-size: 15px; line-height: 1.6; }\n    .ols-figure-card { margin: 26px 0 4px; border: 1px solid var(--border); border-radius: 26px; overflow: hidden; background: #ffffff; box-shadow: var(--inner-shadow); }\n    .ols-figure-image { width: 100%; min-height: 290px; display: flex; align-items: center; justify-content: center; background: #ffffff; padding: 24px; }\n    .ols-figure-image img { max-width: 100%; height: auto; display: block; }\n    .ols-figure-caption { padding: 18px 24px 22px; background: linear-gradient(135deg, #ffffff, #f8fbff); border-top: 1px solid var(--border); }\n    .ols-figure-caption p { margin: 0; color: #5f6b85; font-size: clamp(15px, 1.3vw, 17px); line-height: 1.6; font-weight: 300; font-style: italic; }\n    .ols-table-wrap { overflow: hidden; border-radius: 22px; border: 1px solid var(--border); background: #ffffff; margin-top: 18px; }\n    .ols-table { width: 100%; border-collapse: collapse; table-layout: fixed; }\n    .ols-table th { background: var(--navy); color: #ffffff; padding: 16px; text-align: left; font-size: clamp(14px, 1.2vw, 17px); font-weight: 600; overflow-wrap: anywhere; }\n    .ols-table td { padding: 16px; border-bottom: 1px solid var(--border); font-size: clamp(14px, 1.15vw, 16px); line-height: 1.45; color: var(--body-text); vertical-align: top; overflow-wrap: anywhere; }\n    .ols-table tr:last-child td { border-bottom: none; }\n    .ols-h5p-card { background: linear-gradient(135deg, #ffffff 0%, #f7f0ff 100%); }\n    .ols-h5p-frame { margin-top: 22px; padding: 18px; border-radius: 24px; background: #ffffff; border: 1px solid var(--border); box-shadow: inset 0 0 0 1px rgba(28, 36, 75, 0.03); }\n    .ols-faq-list { display: grid; gap: 14px; margin-top: 18px; }\n    .ols-faq-item { background: #ffffff; border: 1px solid var(--border); border-radius: 18px; padding: 18px 20px; box-shadow: var(--inner-shadow); }\n    .ols-faq-item h3 { margin: 0 0 8px; font-size: 20px; line-height: 1.3; color: var(--navy); }\n    .ols-faq-item p { margin: 0; font-size: 16px; line-height: 1.65; color: var(--body-text); }\n    .ols-related-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; margin-top: 18px; }\n    .ols-related-item { border: 1px solid var(--border); border-radius: 18px; padding: 18px; background: #ffffff; color: var(--navy); text-decoration: none; font-weight: 600; line-height: 1.5; transition: transform 0.2s ease, box-shadow 0.2s ease; }\n    .ols-related-item:hover { transform: translateY(-2px); box-shadow: 0 10px 22px rgba(28, 36, 75, 0.08); }\n\n    @media (max-width: 1050px) {\n      .ols-main { max-width: none; }\n      .ols-related-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }\n    }\n\n    @media (max-width: 760px) {\n      .ols-title-card, .ols-note-card, .ols-h5p-card, .ols-related-card, .ols-faq-card { padding: 24px 18px; border-radius: 22px; }\n      .ols-note-title { align-items: flex-start; }\n      .ols-related-grid { grid-template-columns: 1fr; }\n      .ols-figure-card { border-radius: 22px; }\n      .ols-figure-image { min-height: 220px; padding: 16px; }\n      .ols-figure-caption { padding: 16px; }\n      .ols-table-wrap { border: none; background: transparent; }\n      .ols-table, .ols-table thead, .ols-table tbody, .ols-table th, .ols-table td, .ols-table tr { display: block; width: 100%; }\n      .ols-table { border-collapse: separate; border-spacing: 0; }\n      .ols-table thead { display: none; }\n      .ols-table tr { margin-bottom: 14px; border: 1px solid var(--border); border-radius: 18px; overflow: hidden; background: #ffffff; box-shadow: var(--inner-shadow); }\n      .ols-table td { border-bottom: 1px solid var(--border); padding: 14px 16px; overflow-wrap: anywhere; }\n      .ols-table td:last-child { border-bottom: none; }\n      .ols-table td::before { content: attr(data-label); display: block; margin-bottom: 6px; font-size: 13px; font-weight: 700; color: var(--blue); }\n      .ols-author { align-items: flex-start; padding: 22px 18px; border-radius: 22px; }\n      .ols-author-avatar-img { width: 72px; height: 72px; }\n      .ols-author-title { font-size: 24px; }\n      .ols-author-description { font-size: 15px; }\n    }\n  \n    .ols-figure-placeholder .ols-placeholder-box { border: 2px dashed #c9973a; background: #fffaf0; border-radius: 16px; padding: 26px 22px; font-weight: 700; color: #7a4b12; 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\">\r\n  <div class=\"ols-sidebar-header\">\r\n    <h3>Revision Notes<\/h3>\r\n    <p>A Level Chemistry<\/p>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Topic 3 Bonding &amp; Structure<\/h4>\r\n\r\n    <ul class=\"ols-topic-list\">\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/ionic-bonding-structure\/\">Ionic Bonding &amp; Structure<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/ionic-bonding-structure\/nature-of-ionic-bonding\/\">Nature of Ionic Bonding<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/ionic-bonding-structure\/polarisation-of-ions\/\">Polarisation of Ions<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/ionic-bonding-structure\/physical-properties-of-ionic-compounds\/\">Physical Properties of Ionic Compounds<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/nature-of-covalent-bonding\/\">Nature of Covalent Bonding<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/nature-of-covalent-bonding\/covalent-bonding-and-structure\/\">Covalent Bonding<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/nature-of-covalent-bonding\/dative-covalent-bonding\/\">Dative Covalent Bonding<\/a>\r\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/nature-of-covalent-bonding\/giant-covalent-structures\/\">Giant Covalent Structures<\/a>\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/nature-of-covalent-bonding\/electronegativity\/\">Electronegativity<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/\">Shapes of Molecules<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/linear\/\">Linear<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/trigonal-planar\/\">Trigonal Planar<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/tetrahedral\/\">Tetrahedral<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/trigonal-pyramidal\/\">Trigonal Pyramidal<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/bent\/\">Bent<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/trigonal-bipyramidal\/\">Trigonal Bipyramidal<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/octahedral\/\">Octahedral<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/square-planar\/\">Square Planar<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/square-pyramidal\/\">Square Pyramidal<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/distorted-t\/\">Distorted T<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/shapes-of-molecules\/seesaw\/\">SeeSaw<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/polar-and-non-polar-molecules\/\">Polar &amp; Non-Polar Molecules<\/a>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/metallic-bonding\/\">Nature of Metallic Bonding<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/metallic-bonding\/metallic-bonding-structure\/\">Metallic Bonding &amp; Structure<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/metallic-bonding\/physical-properties-of-metals\/\">Physical Properties of Metals<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/structure-types\/\">Structure Types<\/a>\n          <\/li>\r\n    <\/ul>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Next Topics<\/h4>\r\n\r\n    <ul class=\"ols-topic-list\">\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-4-organic-chemistry-and-alkanes\/\">Organic Chemistry &amp; Alkanes<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/\">Alkenes<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-6-energetics\/\">Energetics<\/a>\r\n      <\/li>\r\n    <\/ul>\r\n  <\/div>\r\n<\/aside>\r\n\r\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\"], a[aria-current]').forEach(function(a) {\r\n      a.removeAttribute('aria-current');\r\n      a.removeAttribute('tabindex');\r\n      a.removeAttribute('data-ols-disabled-parent');\r\n    });\r\n\r\n    links.forEach(function(a) {\r\n      try {\r\n        var href = a.getAttribute('href');\r\n\r\n        if (!href || href === '#' || href.charAt(0) === '#') {\r\n          return;\r\n        }\r\n\r\n        var linkPath = normalisePath(new URL(href, window.location.origin).pathname);\r\n\r\n        if (!linkPath) {\r\n          return;\r\n        }\r\n\r\n        if (currentPath === linkPath || currentPath.indexOf(linkPath + '\/') === 0) {\r\n          if (linkPath.length > matchedLength) {\r\n            matched = a;\r\n            matchedLength = linkPath.length;\r\n          }\r\n        }\r\n      } catch(e) {}\r\n    });\r\n\r\n    if (matched) {\r\n      var matchedLi = matched.closest('li');\r\n      var parentSub = matched.closest('.ols-subtopic-list');\r\n\r\n      if (parentSub) {\r\n        if (matchedLi) {\r\n          matchedLi.classList.add('active');\r\n          matched.setAttribute('aria-current', 'page');\r\n        }\r\n\r\n        var parentLi = parentSub.closest('li');\r\n\r\n        if (parentLi) {\r\n          parentLi.classList.add('parent-active', 'active-main');\r\n\r\n          var parentLink = parentLi.querySelector(':scope > a');\r\n\r\n          if (parentLink) {\r\n            parentLink.setAttribute('aria-current', 'true');\r\n            parentLink.setAttribute('tabindex', '-1');\r\n            parentLink.setAttribute('data-ols-disabled-parent', '1');\r\n          }\r\n        }\r\n      } else {\r\n        if (matchedLi) {\r\n          matchedLi.classList.add('parent-active', 'active-main');\r\n          matched.setAttribute('aria-current', 'page');\r\n          matched.setAttribute('tabindex', '-1');\r\n          matched.setAttribute('data-ols-disabled-parent', '1');\r\n        }\r\n      }\r\n    }\r\n\r\n    return true;\r\n  }\r\n\r\n  if (!highlightActive()) {\r\n    document.addEventListener('DOMContentLoaded', highlightActive);\r\n  }\r\n})();\r\n<\/script>\r\n\n\n  <main class=\"ols-main\">\n      <nav 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\/edexcel-international\/\">Edexcel International<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/\">Topic 3 Bonding and Structure<\/a> \/\n<span>Structure Types<\/span>\n<\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Structure Types<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to the four types of solid lattice, giant ionic, giant metallic, giant covalent and simple molecular: which particles they contain, what holds them together, and how that decides melting point, conductivity, solubility and the energy changes on melting and boiling.<\/p>\n\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Exam board: Edexcel International<\/div>\n          <div class=\"ols-badge\">Topic 3: Bonding &amp; Structure<\/div>\n          <div class=\"ols-badge\">Level: A Level Chemistry<\/div>\n        <\/div>\n\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\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\n        View LinkedIn Profile\n\n      <\/a>\n\n    <\/div>\n\n  <\/div>\n      <\/header>\n\n      <article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">1<\/div>\n<h2>The Four Types of Solid Lattice<\/h2>\n<\/div>\n<p>Every crystalline solid is a regular, repeating arrangement of particles: a <strong>lattice<\/strong>. What decides a solid&#8217;s properties is not the lattice pattern itself but <strong>which particles<\/strong> sit at the lattice points and <strong>which forces<\/strong> hold them there. There are four cases to know.<\/p>\n<div class=\"ols-table-wrap\">\n<table class=\"ols-table\">\n<thead>\n<tr><th>Lattice type<\/th><th>Particles<\/th><th>Forces holding the lattice together<\/th><th>Examples<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td><strong>Giant ionic<\/strong><\/td><td>Positive and negative ions<\/td><td>Strong electrostatic attraction between oppositely charged ions, acting in all directions<\/td><td>NaCl, MgO, CaF<sub>2<\/sub><\/td><\/tr>\n<tr><td><strong>Giant metallic<\/strong><\/td><td>Positive metal ions and delocalised electrons<\/td><td>Strong electrostatic attraction between the ions and the sea of delocalised electrons<\/td><td>Mg, Cu, Na<\/td><\/tr>\n<tr><td><strong>Giant covalent (macromolecular)<\/strong><\/td><td>Atoms<\/td><td>Strong covalent bonds throughout the whole structure<\/td><td>Diamond, graphite, SiO<sub>2<\/sub><\/td><\/tr>\n<tr><td><strong>Simple molecular<\/strong><\/td><td>Molecules<\/td><td>Weak intermolecular forces between molecules (the covalent bonds inside each molecule are strong but are not broken on melting)<\/td><td>I<sub>2<\/sub>, ice, C<sub>60<\/sub>, CO<sub>2<\/sub><\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>The word <strong>giant<\/strong> means the bonding continues throughout the crystal, so there is no separate molecule to point to. In a <strong>simple molecular<\/strong> solid there are two different forces: strong covalent bonds within each molecule and weak forces between them, and only the weak forces are overcome when the solid melts.<\/p>\n<div class=\"ols-figure-card ols-figure-placeholder\">\n<div class=\"ols-figure-image\"><div class=\"ols-placeholder-box\">[3D MODEL NEEDED: Create an interactive 3D educational model comparing the four types of solid lattice. Show a selector with four structures, each drawn as a small block about three repeat units wide: * Giant ionic (sodium chloride): alternating small purple Na\u207a and large green Cl\u207b spheres in a cubic lattice, each ion surrounded by six of the opposite charge, with a toggle that draws the electrostatic attractions as thin lines in all directions. * Giant metallic (magnesium): grey Mg\u00b2\u207a spheres in close-packed layers inside a translucent blue sea of small moving electron dots. * Giant covalent (diamond): black carbon spheres each joined tetrahedrally to four others by grey rods. * Simple molecular (iodine): purple I\u2082 dumbbells arranged in a regular lattice with wide gaps, and a toggle that draws the weak London forces between molecules as faint dotted lines. For every structure show a button \u201cHeat it\u201d that animates what breaks on melting: ions separate (ionic), ions slide while the electron sea stays (metallic), covalent bonds must break (giant covalent), only the dotted intermolecular lines break while the I\u2082 molecules stay intact (simple molecular), each labelled with what is overcome and the typical melting point (801 \u00b0C, 650 \u00b0C, above 3500 \u00b0C, 114 \u00b0C). A toggle \u201cConducts?\u201d colours the mobile charge carriers where they exist (ions when molten in ionic, delocalised electrons in metallic) and labels the other two \u201cno mobile charged particles\u201d. Particles must not overlap and must stay to scale within each structure. Use translucent spheres so interior particles remain visible. Label each lattice type, the particles present and the forces between them. Allow the viewer to rotate and zoom, switch structures, toggle forces, charge carriers and labels, run and reset the heating animation, and switch between front, corner and top views. Include a small x\u2013y\u2013z axis guide. Use a white background, clear typography and restrained textbook styling. Title: Four Types of Solid Lattice: What Holds Them Together.]<\/div><\/div>\n<div class=\"ols-figure-caption\"><p>The four lattice types side by side: rotate each to see what sits at the lattice points and what holds them together.<\/p><\/div>\n<\/div>\n<div class=\"ols-key-box\">\n<p><strong>Key idea:<\/strong> Three giant lattices, one molecular lattice. Melting a giant lattice breaks strong bonds; melting a molecular lattice only overcomes weak intermolecular forces.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">2<\/div>\n<h2>Melting Point Follows the Force That Must Be Overcome<\/h2>\n<\/div>\n<p>Melting a solid means giving the particles enough energy to break free from their lattice positions. The energy needed depends on the force holding them, so melting points fall into two clear bands.<\/p>\n<div class=\"ols-table-wrap\">\n<table class=\"ols-table\">\n<thead>\n<tr><th>Substance<\/th><th>Lattice type<\/th><th>What must be overcome on melting<\/th><th>Melting point \/ \u00b0C<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td><strong>Sodium chloride<\/strong><\/td><td>Giant ionic<\/td><td>Strong electrostatic attraction between ions<\/td><td>801<\/td><\/tr>\n<tr><td><strong>Magnesium<\/strong><\/td><td>Giant metallic<\/td><td>Strong attraction between ions and delocalised electrons<\/td><td>650<\/td><\/tr>\n<tr><td><strong>Diamond<\/strong><\/td><td>Giant covalent<\/td><td>Strong covalent bonds<\/td><td>above 3500 (sublimes)<\/td><\/tr>\n<tr><td><strong>Iodine<\/strong><\/td><td>Simple molecular<\/td><td>Weak London forces between I<sub>2<\/sub> molecules<\/td><td>114<\/td><\/tr>\n<tr><td><strong>Ice<\/strong><\/td><td>Simple molecular<\/td><td>Hydrogen bonds between H<sub>2<\/sub>O molecules<\/td><td>0<\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>Within a band the details matter. Among ionic compounds a higher charge and a smaller ionic radius give stronger attraction and a higher melting point (MgO melts at 2852 \u00b0C, NaCl at 801 \u00b0C). Among metals more delocalised electrons per ion and a smaller ion give a higher melting point (Mg above Na). Among simple molecular substances the strength of the intermolecular force decides: hydrogen bonds above permanent dipoles above London forces, and larger molecules have stronger London forces.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Exam sentence:<\/strong> Sodium chloride has a high melting point because a lot of energy is needed to overcome the strong electrostatic attraction between oppositely charged ions in the giant lattice; iodine has a low melting point because only weak London forces between I<sub>2<\/sub> molecules need to be overcome.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card purple\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">3<\/div>\n<h2>Electrical Conductivity Needs Mobile Charged Particles<\/h2>\n<\/div>\n<p>A substance conducts electricity only if it contains <strong>charged particles that are free to move<\/strong>. Apply that one test to each lattice type in each state.<\/p>\n<div class=\"ols-table-wrap\">\n<table class=\"ols-table\">\n<thead>\n<tr><th>Lattice type<\/th><th>Solid<\/th><th>Molten or dissolved<\/th><th>Reason<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td><strong>Giant ionic<\/strong><\/td><td>Does not conduct<\/td><td>Conducts<\/td><td>Ions are fixed in the solid lattice; when molten or in solution they are free to move and carry charge<\/td><\/tr>\n<tr><td><strong>Giant metallic<\/strong><\/td><td>Conducts<\/td><td>Conducts<\/td><td>Delocalised electrons are free to move through the lattice in both states<\/td><\/tr>\n<tr><td><strong>Giant covalent<\/strong><\/td><td>Does not conduct (except graphite)<\/td><td>Does not conduct<\/td><td>All outer electrons are held in localised covalent bonds; graphite alone has one delocalised electron per carbon<\/td><\/tr>\n<tr><td><strong>Simple molecular<\/strong><\/td><td>Does not conduct<\/td><td>Does not conduct<\/td><td>Molecules are neutral and there are no delocalised electrons or ions<\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>The ionic case is the one examiners test most: the solid is an insulator, the melt is a conductor, and the reason is the <strong>mobility<\/strong> of the ions, not whether ions exist.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Exam focus:<\/strong> Never write &#8220;ionic compounds conduct electricity&#8221;. Write &#8220;ionic compounds conduct when molten or aqueous because the ions are free to move; in the solid the ions are held in fixed positions&#8221;.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">4<\/div>\n<h2>Solubility and Hardness<\/h2>\n<\/div>\n<ul>\n<li><strong>Giant ionic:<\/strong> many dissolve in water because the polar water molecules attract the ions and hydrate them; insoluble in non-polar solvents. Hard but brittle, because shifting a layer brings like charges together and the layers repel.<\/li>\n<li><strong>Giant metallic:<\/strong> insoluble in all common solvents; malleable and ductile because layers of ions slide past each other while the electron sea keeps the attraction.<\/li>\n<li><strong>Giant covalent:<\/strong> insoluble in everything; very hard (diamond) or soft and slippery (graphite, where layers slide).<\/li>\n<li><strong>Simple molecular:<\/strong> soft, easily crushed; solubility follows polarity (&#8220;like dissolves like&#8221;): iodine dissolves in hexane, not in water; ice melts into water and sugar dissolves in it because they hydrogen bond.<\/li>\n<\/ul>\n<div class=\"ols-key-box\">\n<p><strong>Key idea:<\/strong> Solubility is about the forces between solute and solvent; hardness is about how easily the lattice can be deformed without the forces breaking.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">5<\/div>\n<h2>Energy Changes on Changes of State<\/h2>\n<\/div>\n<p>When a solid melts or a liquid boils, energy is absorbed to overcome the forces between particles while the temperature stays constant: the <strong>enthalpy of fusion<\/strong> and <strong>enthalpy of vaporisation<\/strong>. The size of each depends on the lattice type.<\/p>\n<div class=\"ols-table-wrap\">\n<table class=\"ols-table\">\n<thead>\n<tr><th>Change<\/th><th>Giant lattices<\/th><th>Simple molecular<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td><strong>Melting<\/strong><\/td><td>Large energy input: strong ionic, metallic or covalent bonds are partly broken<\/td><td>Small energy input: some weak intermolecular forces are overcome<\/td><\/tr>\n<tr><td><strong>Boiling<\/strong><\/td><td>Very large: the remaining strong bonds are broken so the particles separate completely<\/td><td>Small: all the remaining intermolecular forces are overcome; the covalent bonds inside the molecules survive<\/td><\/tr>\n<tr><td><strong>Sign of the enthalpy change<\/strong><\/td><td>Endothermic (positive)<\/td><td>Endothermic (positive)<\/td><\/tr>\n<tr><td><strong>Reverse change (freezing, condensing)<\/strong><\/td><td>Exothermic: the same amount of energy is released as the forces re-form<\/td><td>Exothermic<\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>On a heating curve the two flat plateaus are melting and boiling: the energy supplied is going into overcoming forces, not into raising the temperature. The plateaus are longer and sit at higher temperatures for giant lattices than for simple molecular substances.<\/p>\n<div class=\"ols-figure-card ols-figure-placeholder\">\n<div class=\"ols-figure-image\"><div class=\"ols-placeholder-box\">[IMAGE NEEDED: Two heating curves on one set of axes (temperature against energy supplied): a giant ionic solid with long plateaus at 801 \u00b0C and 1413 \u00b0C, and a simple molecular solid with short plateaus at 114 \u00b0C and 184 \u00b0C; each plateau labelled with the force being overcome.]<\/div><\/div>\n<div class=\"ols-figure-caption\"><p>Energy supplied during a plateau overcomes forces between particles; the temperature does not rise until they are overcome.<\/p><\/div>\n<\/div>\n<div class=\"ols-key-box\">\n<p><strong>Exam sentence:<\/strong> During melting the temperature stays constant because the energy supplied is used to overcome the forces between the particles rather than to increase their kinetic energy.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">6<\/div>\n<h2>Deducing the Structure from Data<\/h2>\n<\/div>\n<p>Exam questions often give a table of properties for unnamed substances and ask for the structure and bonding. Work through the tests in order.<\/p>\n<div class=\"ols-table-wrap\">\n<table class=\"ols-table\">\n<thead>\n<tr><th>Question to ask<\/th><th>If yes<\/th><th>If no<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td><strong>Does it conduct as a solid?<\/strong><\/td><td>Metallic (or graphite)<\/td><td>Go on<\/td><\/tr>\n<tr><td><strong>Does it conduct when molten but not as a solid?<\/strong><\/td><td>Giant ionic<\/td><td>Go on<\/td><\/tr>\n<tr><td><strong>Is the melting point very high (above about 1000 \u00b0C) with no conduction in any state?<\/strong><\/td><td>Giant covalent<\/td><td>Go on<\/td><\/tr>\n<tr><td><strong>Is the melting point low and there is no conduction?<\/strong><\/td><td>Simple molecular<\/td><td>Re-check the data<\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>Then confirm with solubility: ionic solids often dissolve in water, molecular solids dissolve in solvents of similar polarity, giant covalent and metallic solids dissolve in neither.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Exam focus:<\/strong> State the structure, then justify it with two properties from the data, naming the particles and the forces each time.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">7<\/div>\n<h2>Common Exam Mistakes<\/h2>\n<\/div>\n<ul>\n<li>Saying a simple molecular solid melts when &#8220;the covalent bonds break&#8221;. Only the intermolecular forces are overcome; the molecules stay intact.<\/li>\n<li>Saying ionic compounds conduct electricity without stating the condition (molten or aqueous) and the reason (ions free to move).<\/li>\n<li>Calling the attraction in a metal &#8220;between atoms&#8221; or &#8220;between ions&#8221;. It is between positive ions and delocalised electrons.<\/li>\n<li>Describing diamond as a molecule. It is a giant covalent lattice with no separate molecules.<\/li>\n<li>Explaining a high melting point by &#8220;strong bonds&#8221; alone. Name the type of bond or force and the particles it acts between.<\/li>\n<\/ul>\n<div class=\"ols-key-box\">\n<p><strong>Exam sentence:<\/strong> Particles, force between them, consequence: every structure-and-bonding answer follows that pattern.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card purple\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">8<\/div>\n<h2>Where This Sits in the Edexcel International Specification<\/h2>\n<\/div>\n<p>Topic 3 asks you to describe ionic crystals as giant lattices of ions (3.4), metals as giant lattices of metal ions in a sea of delocalised electrons (3.20) and the giant covalent structures of graphite, diamond and graphene (3.12), and to use these models to interpret physical properties (3.22). This page compares the four lattice types in one place, which is how they are examined.<\/p><div class=\"ols-key-box\">\n<p><strong>Exam focus:<\/strong> A giant lattice needs strong bonds broken to melt it; a simple molecular lattice needs only weak intermolecular forces overcome. Say which, and name the particles.<\/p>\n<\/div>\n<\/article>\n<section class=\"ols-h5p-card\">\n<h2>Check Your Understanding<\/h2>\n<p>Use these short activities to test the four lattice types on substances that are not used as examples on this page.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-459\" class=\"h5p-iframe\" data-content-id=\"459\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Structure Types Drag: Identifying Four Solids\"><\/iframe><\/div><\/div>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-460\" class=\"h5p-iframe\" data-content-id=\"460\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Structure Types MCQ: Potassium Bromide\"><\/iframe><\/div><\/div>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-461\" class=\"h5p-iframe\" data-content-id=\"461\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Structure Types MCQ: Why Silicon Carbide Melts Above Aluminium\"><\/iframe><\/div><\/div>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-462\" class=\"h5p-iframe\" data-content-id=\"462\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Structure Types MCQ: The Heating Curve Plateau\"><\/iframe><\/div><\/div>\n<\/section>\n<section class=\"ols-course-cta-ionic-metallic\" id=\"olsCourseCtaIonicMetallic001\">\n  <style>\n    .ols-course-cta-ionic-metallic,\n    .ols-course-cta-ionic-metallic * {\n      box-sizing: border-box;\n    }\n\n    .ols-course-cta-ionic-metallic {\n      --navy: #1C244B;\n      --blue: #2563eb;\n      --body-text: #1f2937;\n      --grey-text: #667085;\n      --border: rgba(28, 36, 75, 0.14);\n      --shadow: 0 18px 45px rgba(28, 36, 75, 0.12);\n      --inner-shadow: 0 10px 26px rgba(28, 36, 75, 0.08);\n\n      width: 100%;\n      margin: 30px 0 24px;\n      font-family: Poppins, Arial, sans-serif;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-card {\n      overflow: hidden;\n      border-radius: 30px;\n      border: 1px solid var(--border);\n      background:\n        radial-gradient(circle at top left, rgba(37, 99, 235, 0.16), transparent 34%),\n        linear-gradient(135deg, #ffffff 0%, #f8fbff 100%);\n      box-shadow: var(--shadow);\n      padding: 30px;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-top {\n      display: grid;\n      grid-template-columns: minmax(260px, 0.9fr) minmax(0, 1.1fr);\n      gap: 28px;\n      align-items: center;\n      margin-bottom: 24px;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-image-link {\n      display: block;\n      text-decoration: none;\n      border-radius: 24px;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-image {\n      width: 100%;\n      border-radius: 24px;\n      overflow: hidden;\n      border: 1px solid var(--border);\n      background: #ffffff;\n      box-shadow: var(--inner-shadow);\n      transition:\n        transform 0.35s ease,\n        box-shadow 0.35s ease;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-image img {\n      width: 100%;\n      height: auto;\n      display: block;\n      transition: transform 0.45s ease;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-image-link:hover .ols-course-cta-image {\n      transform: translateY(-8px) scale(1.015);\n      box-shadow:\n        0 26px 60px rgba(28, 36, 75, 0.18),\n        0 0 0 1px rgba(37, 99, 235, 0.12);\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-image-link:hover .ols-course-cta-image img {\n      transform: scale(1.03);\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-header-row {\n      display: flex;\n      flex-wrap: wrap;\n      align-items: center;\n      justify-content: space-between;\n      gap: 14px;\n      margin-bottom: 18px;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-kicker {\n      display: inline-flex;\n      align-items: center;\n      padding: 8px 14px;\n      border-radius: 999px;\n      background: #ffffff;\n      border: 1px solid rgba(37, 99, 235, 0.18);\n      color: var(--blue);\n      font-size: 14px;\n      line-height: 1.2;\n      font-weight: 700;\n      box-shadow: var(--inner-shadow);\n    }\n\n    .ols-course-cta-ionic-metallic h2 {\n      margin: 0 0 14px;\n      font-size: clamp(28px, 3.5vw, 42px);\n      line-height: 1.15;\n      font-weight: 800;\n      letter-spacing: -0.03em;\n      color: #111827;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-intro-stats {\n      display: grid;\n      grid-template-columns: minmax(0, 1.08fr) minmax(320px, 0.92fr);\n      gap: 24px;\n      align-items: stretch;\n      margin: 0 0 30px;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-intro {\n      margin: 0;\n      color: var(--body-text);\n      font-size: clamp(16px, 1.4vw, 18px);\n      line-height: 1.7;\n      font-weight: 300;\n      align-self: center;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-stats {\n      display: grid;\n      grid-template-columns: repeat(2, minmax(0, 1fr));\n      gap: 14px;\n      margin: 0;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-stat {\n      background: #ffffff;\n      border: 1px solid var(--border);\n      border-radius: 18px;\n      padding: 16px;\n      box-shadow: var(--inner-shadow);\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-stat span {\n      display: block;\n      margin-bottom: 6px;\n      color: var(--grey-text);\n      font-size: 13px;\n      line-height: 1.35;\n      font-weight: 700;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-stat strong {\n      display: block;\n      color: var(--navy);\n      font-size: 18px;\n      line-height: 1.35;\n      font-weight: 800;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-features {\n      display: grid;\n      grid-template-columns: repeat(2, minmax(0, 1fr));\n      gap: 14px;\n      margin: 0 0 30px;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-feature {\n      background: rgba(255, 255, 255, 0.78);\n      border: 1px solid var(--border);\n      border-radius: 18px;\n      padding: 16px 18px;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-feature h3 {\n      margin: 0 0 6px;\n      color: var(--navy);\n      font-size: 18px;\n      line-height: 1.3;\n      font-weight: 800;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-feature p {\n      margin: 0;\n      color: var(--body-text);\n      font-size: 15px;\n      line-height: 1.6;\n      font-weight: 300;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-animation-wrap {\n      position: relative;\n      margin: 0 0 30px;\n      border-radius: 0;\n      overflow: visible;\n      border: 0;\n      background: transparent;\n      box-shadow: none;\n      padding: 0;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-animation-title {\n      margin: 0 0 18px;\n      text-align: center;\n      color: var(--navy);\n      font-size: clamp(26px, 3.2vw, 40px);\n      line-height: 1.15;\n      font-weight: 700;\n      letter-spacing: -0.03em;\n      text-shadow: -9px 0 9px rgba(28, 36, 75, 0.10);\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-frame-shell {\n      position: relative;\n      width: 100%;\n      height: 620px;\n      border-radius: 24px;\n      overflow: hidden;\n      background:\n        radial-gradient(circle at top left, rgba(70, 127, 247, 0.14), transparent 34%),\n        linear-gradient(135deg, #f8fbff 0%, #e9efff 100%);\n      box-shadow: 0 24px 64px rgba(28, 36, 75, 0.18);\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-frame-shell iframe {\n      display: block;\n      width: 100%;\n      height: 100%;\n      border: 0;\n      background: #e9efff;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-start-overlay {\n      position: absolute;\n      inset: 0;\n      z-index: 5;\n      display: flex;\n      align-items: center;\n      justify-content: center;\n      border: 0;\n      cursor: pointer;\n      background:\n        radial-gradient(circle at center, rgba(255, 255, 255, 0.26), rgba(28, 36, 75, 0.28)),\n        url(\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/04\/edexcel-international-a-level-chemistry-topic-3a-3d-ionic-metallic-bonding-course-banner.jpg\");\n      background-size: cover;\n      background-position: center;\n      transition:\n        opacity 0.35s ease,\n        visibility 0.35s ease;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-start-overlay::before {\n      content: \"\";\n      position: absolute;\n      inset: 0;\n      background: rgba(28, 36, 75, 0.30);\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-start-overlay.is-hidden {\n      opacity: 0;\n      visibility: hidden;\n      pointer-events: none;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-start-content {\n      position: relative;\n      z-index: 2;\n      display: grid;\n      justify-items: center;\n      gap: 16px;\n      padding: 24px;\n      text-align: center;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-play-circle {\n      width: 96px;\n      height: 96px;\n      border-radius: 50%;\n      background: #ffffff;\n      color: var(--navy);\n      display: flex;\n      align-items: center;\n      justify-content: center;\n      box-shadow:\n        0 18px 40px rgba(28, 36, 75, 0.30),\n        0 0 0 12px rgba(255, 255, 255, 0.22);\n      animation: olsAnimationPlayPulse001 1.8s ease-in-out infinite;\n      transition:\n        transform 0.25s ease,\n        background 0.25s ease,\n        color 0.25s ease;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-start-overlay:hover .ols-animation-play-circle {\n      transform: scale(1.08);\n      background: var(--navy);\n      color: #ffffff;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-play-icon {\n      width: 0;\n      height: 0;\n      margin-left: 7px;\n      border-top: 18px solid transparent;\n      border-bottom: 18px solid transparent;\n      border-left: 28px solid currentColor;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-start-text {\n      max-width: 540px;\n      margin: 0;\n      color: #ffffff;\n      font-size: clamp(20px, 3vw, 32px);\n      line-height: 1.2;\n      font-weight: 800;\n      text-shadow: 0 8px 20px rgba(0, 0, 0, 0.28);\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-pause-button {\n      position: absolute;\n      left: 16px;\n      bottom: 16px;\n      z-index: 7;\n      display: none;\n      align-items: center;\n      justify-content: center;\n      min-width: 92px;\n      padding: 10px 16px;\n      border: 0;\n      border-radius: 999px;\n      background: rgba(28, 36, 75, 0.92);\n      color: #ffffff;\n      font-family: Poppins, Arial, sans-serif;\n      font-size: 14px;\n      line-height: 1.2;\n      font-weight: 800;\n      cursor: pointer;\n      box-shadow: 0 12px 28px rgba(28, 36, 75, 0.24);\n      transition:\n        transform 0.2s ease,\n        background 0.2s ease,\n        box-shadow 0.2s ease;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-pause-button:hover {\n      transform: translateY(-2px);\n      background: var(--blue);\n      box-shadow: 0 16px 34px rgba(37, 99, 235, 0.28);\n    }\n\n    .ols-course-cta-ionic-metallic .ols-animation-pause-button.is-visible {\n      display: inline-flex;\n    }\n\n    @keyframes olsAnimationPlayPulse001 {\n      0% {\n        box-shadow:\n          0 18px 40px rgba(28, 36, 75, 0.30),\n          0 0 0 0 rgba(255, 255, 255, 0.40);\n      }\n\n      70% {\n        box-shadow:\n          0 18px 40px rgba(28, 36, 75, 0.30),\n          0 0 0 18px rgba(255, 255, 255, 0);\n      }\n\n      100% {\n        box-shadow:\n          0 18px 40px rgba(28, 36, 75, 0.30),\n          0 0 0 0 rgba(255, 255, 255, 0);\n      }\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-video-status {\n      margin: 14px 0 0;\n      text-align: center;\n      color: var(--grey-text);\n      font-size: 13px;\n      line-height: 1.5;\n      font-weight: 500;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-cta-bottom {\n      display: flex;\n      justify-content: center;\n      padding-top: 22px;\n      border-top: 1px solid var(--border);\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-button {\n      display: inline-flex;\n      align-items: center;\n      justify-content: center;\n      padding: 15px 28px;\n      border-radius: 999px;\n      background: var(--navy);\n      color: #ffffff;\n      text-decoration: none;\n      font-size: 16px;\n      line-height: 1.2;\n      font-weight: 800;\n      box-shadow: 0 12px 26px rgba(28, 36, 75, 0.18);\n      transition:\n        transform 0.2s ease,\n        background 0.2s ease,\n        box-shadow 0.2s ease;\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-button:hover {\n      transform: translateY(-2px);\n      background: var(--blue);\n      color: #ffffff;\n      box-shadow: 0 16px 32px rgba(37, 99, 235, 0.24);\n    }\n\n    .ols-course-cta-ionic-metallic .ols-course-button-top {\n      flex-shrink: 0;\n      padding: 12px 22px;\n      font-size: 15px;\n    }\n\n    @media (max-width: 900px) {\n      .ols-course-cta-ionic-metallic .ols-course-cta-top {\n        grid-template-columns: 1fr;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-course-cta-image-link {\n        max-width: 520px;\n        margin: 0 auto;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-course-cta-intro-stats {\n        grid-template-columns: 1fr;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-animation-frame-shell {\n        height: 520px;\n      }\n    }\n\n    @media (max-width: 760px) {\n      .ols-course-cta-ionic-metallic {\n        margin: 26px 0 22px;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-course-cta-card {\n        padding: 20px;\n        border-radius: 24px;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-course-cta-header-row {\n        align-items: stretch;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-course-button-top {\n        width: 100%;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-course-cta-stats,\n      .ols-course-cta-ionic-metallic .ols-course-cta-features {\n        grid-template-columns: 1fr;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-course-animation-wrap {\n        padding: 0;\n        border-radius: 0;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-animation-frame-shell {\n        height: 420px;\n        border-radius: 18px;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-animation-play-circle {\n        width: 76px;\n        height: 76px;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-animation-play-icon {\n        border-top-width: 14px;\n        border-bottom-width: 14px;\n        border-left-width: 22px;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-animation-pause-button {\n        left: 12px;\n        bottom: 12px;\n        min-width: 84px;\n        padding: 9px 14px;\n        font-size: 13px;\n      }\n\n      .ols-course-cta-ionic-metallic .ols-course-button {\n        width: 100%;\n      }\n    }\n  <\/style>\n\n  <div class=\"ols-course-cta-card\">\n\n    <div class=\"ols-course-cta-top\">\n\n      <a class=\"ols-course-cta-image-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/ionic-bonding-metallic-bonding-edexcel-3a-d\/\" aria-label=\"Open the Edexcel International A Level Chemistry Topic 3A\/D Ionic Bonding and Metallic Bonding course page\">\n\n        <div class=\"ols-course-cta-image\">\n          <img decoding=\"async\"\n            src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/04\/edexcel-international-a-level-chemistry-topic-3a-3d-ionic-metallic-bonding-course-banner.jpg\"\n            alt=\"Edexcel International A Level Chemistry Topic 3A\/D Ionic Bonding and Metallic Bonding course banner\"\n          >\n        <\/div>\n\n      <\/a>\n\n      <div class=\"ols-course-cta-content\">\n\n        <div class=\"ols-course-cta-header-row\">\n\n          <div class=\"ols-course-cta-kicker\">\n            Complete Topic 3A\/D Ionic Bonding &#038; Metallic Bonding Course\n          <\/div>\n\n          <a class=\"ols-course-button ols-course-button-top\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/ionic-bonding-metallic-bonding-edexcel-3a-d\/\">\n            View Course\n          <\/a>\n\n        <\/div>\n\n        <h2>\n          Master Ionic Bonding and Metallic Bonding for Edexcel International A Level Chemistry\n        <\/h2>\n\n      <\/div>\n\n    <\/div>\n\n    <div class=\"ols-course-cta-intro-stats\">\n\n      <p class=\"ols-course-cta-intro\">\n        Continue from these free revision notes into the full Topic 3A\/D Ionic Bonding and Metallic Bonding course, with guided video teaching, diagnostic MCQ practice, teacher-marked short-answer questions and a specification assignment with a personalised progress report.\n      <\/p>\n\n      <div class=\"ols-course-cta-stats\">\n\n        <div class=\"ols-course-stat\">\n          <span>Guided learning<\/span>\n          <strong>11 hours<\/strong>\n        <\/div>\n\n        <div class=\"ols-course-stat\">\n          <span>Video lessons<\/span>\n          <strong>288 mins<\/strong>\n        <\/div>\n\n        <div class=\"ols-course-stat\">\n          <span>MCQ practice<\/span>\n          <strong>51 marks<\/strong>\n        <\/div>\n\n        <div class=\"ols-course-stat\">\n          <span>SAQ practice<\/span>\n          <strong>68 marks<\/strong>\n        <\/div>\n\n      <\/div>\n\n    <\/div>\n\n    <div class=\"ols-course-cta-features\">\n\n      <div class=\"ols-course-feature\">\n        <h3>Guided video teaching<\/h3>\n        <p>\n          Learn ions, ionic lattices, polarisation and metallic bonding through structured video lessons with worked examples and walkthroughs.\n        <\/p>\n      <\/div>\n\n      <div class=\"ols-course-feature\">\n        <h3>Instant MCQ feedback<\/h3>\n        <p>\n          Auto-marked MCQ quizzes provide immediate diagnostic feedback for every answer choice.\n        <\/p>\n      <\/div>\n\n      <div class=\"ols-course-feature\">\n        <h3>Teacher-marked SAQs<\/h3>\n        <p>\n          Submit written exam responses and receive chemistry specialist feedback with improvement guidance.\n        <\/p>\n      <\/div>\n\n      <div class=\"ols-course-feature\">\n        <h3>Progress tracking<\/h3>\n        <p>\n          Identify strengths and weaknesses across ions, ionic bonding, ionic radii, polarisation and metallic bonding with targeted reporting.\n        <\/p>\n      <\/div>\n\n    <\/div>\n\n    <div class=\"ols-course-animation-wrap\">\n\n      <h3 class=\"ols-course-animation-title\">\n        See how the course works\n      <\/h3>\n\n      <div class=\"ols-animation-frame-shell\">\n        <iframe\n          id=\"olsCourseAnimationFrame001\"\n          title=\"OLS course preview animation\"\n          loading=\"lazy\"\n          referrerpolicy=\"no-referrer\">\n        <\/iframe>\n\n        <button\n          class=\"ols-animation-start-overlay\"\n          id=\"olsCourseAnimationStart001\"\n          type=\"button\"\n          aria-label=\"Play OLS course preview animation\">\n          <span class=\"ols-animation-start-content\">\n            <span class=\"ols-animation-play-circle\" aria-hidden=\"true\">\n              <span class=\"ols-animation-play-icon\"><\/span>\n            <\/span>\n            <span class=\"ols-animation-start-text\">\n              Play course preview animation\n            <\/span>\n          <\/span>\n        <\/button>\n\n        <button\n          class=\"ols-animation-pause-button\"\n          id=\"olsCourseAnimationPause001\"\n          type=\"button\"\n          aria-label=\"Pause course preview animation\">\n          Pause\n        <\/button>\n      <\/div>\n\n      <p class=\"ols-course-video-status\">\n        Click play to start the course preview animation.\n      <\/p>\n\n    <\/div>\n\n    <div class=\"ols-course-cta-bottom\">\n\n      <a class=\"ols-course-button\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/ionic-bonding-metallic-bonding-edexcel-3a-d\/\">\n        View Ionic Bonding &#038; Metallic Bonding Topic 3A\/D Course\n      <\/a>\n\n    <\/div>\n\n  <\/div>\n\n  <template id=\"olsCourseAnimationTemplate001\">\n<!DOCTYPE html>\n<html lang=\"en\">\n<head>\n<meta charset=\"UTF-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">\n<title>OLS Combined Promo Animation<\/title>\n\n<style>\n*{box-sizing:border-box;}\n\nhtml.ols-animation-paused *,\nhtml.ols-animation-paused *::before,\nhtml.ols-animation-paused *::after{\n  animation-play-state:paused!important;\n}\n\n:root{\n  --ols-video-screen-w:1180;\n  --ols-video-screen-h:664;\n  --ols-video-screen-scale:1;\n  --ols-mcq-screen-w:1360;\n  --ols-mcq-screen-h:1130;\n  --ols-mcq-screen-scale:1;\n  --ols-saq-screen-w:1360;\n  --ols-saq-screen-h:965;\n  --ols-saq-screen-scale:1;\n}\n\nhtml,\nbody{\n  width:100%;\n  height:100%;\n}\n\nbody{\n  margin:0;\n  overflow:hidden;\n  font-family:Poppins,Arial,sans-serif;\n  background:#e9efff;\n}\n\n.ols-combined-stage{\n  position:relative;\n  width:100vw;\n  height:100vh;\n  overflow:hidden;\n  background:\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\n}\n\n.ols-scene{\n  position:absolute;\n  inset:0;\n  width:100vw;\n  height:100vh;\n  opacity:0;\n  visibility:hidden;\n  pointer-events:none;\n}\n\n.ols-scene.active{\n  opacity:1;\n  visibility:visible;\n  pointer-events:auto;\n}\n\n.ols-scene.fade-out{\n  animation:olsSceneFadeOut 0.85s ease forwards;\n}\n\n@keyframes olsSceneFadeOut{\n  to{\n    opacity:0;\n    visibility:hidden;\n  }\n}\n\n.ols-title-cursor{\n  display:inline-block;\n  width:5px;\n  height:0.85em;\n  background:#1C244B;\n  margin-left:8px;\n  transform:translateY(8px);\n  animation:olsBlink 0.8s infinite;\n}\n\n.cursor{\n  display:inline-block;\n  width:3px;\n  height:28px;\n  background:#1c244b;\n  margin-left:3px;\n  transform:translateY(5px);\n  animation:olsBlink 0.8s infinite;\n}\n\n@keyframes olsBlink{\n  0%,45%{opacity:1;}\n  46%,100%{opacity:0;}\n}\n\n.ols-video-stage,\n.ols-mcq-stage,\n.ols-saq-stage{\n  width:100vw;\n  height:100vh;\n  display:flex;\n  justify-content:center;\n  align-items:center;\n  padding:0;\n  overflow:hidden;\n  background:\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\n}\n\n.ols-video-title-screen,\n.ols-mcq-intro-screen,\n.ols-saq-intro{\n  position:absolute;\n  inset:0;\n  z-index:50;\n  display:flex;\n  justify-content:center;\n  align-items:center;\n  background:\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\n  opacity:1;\n  visibility:visible;\n  pointer-events:none;\n}\n\n.ols-video-title-screen.hide{animation:olsVideoTitleFadeOut 0.85s ease forwards;}\n.ols-mcq-intro-screen.hide{animation:olsMcqIntroFadeOut 0.85s ease forwards;}\n.ols-saq-intro.hide{animation:olsSaqIntroFadeOut 0.85s ease forwards;}\n\n@keyframes olsVideoTitleFadeOut{to{opacity:0;visibility:hidden;}}\n@keyframes olsMcqIntroFadeOut{to{opacity:0;visibility:hidden;}}\n@keyframes olsSaqIntroFadeOut{to{opacity:0;visibility:hidden;}}\n\n.ols-video-title-wrap,\n.ols-mcq-intro-title-wrap,\n.ols-saq-intro-title-wrap{\n  max-width:1250px;\n  padding:0 34px;\n  text-align:center;\n}\n\n.ols-video-title,\n.ols-mcq-intro-title,\n.ols-saq-intro-title{\n  margin:0;\n  font-family:Poppins,Arial,sans-serif;\n  font-size:clamp(52px,8vw,124px);\n  font-weight:600;\n  line-height:1.08;\n  color:#1C244B;\n  text-shadow:-9px 0 9px rgba(28,36,75,0.16);\n  letter-spacing:-0.045em;\n}\n\n#videoTitleText,\n#mcqIntroTitleText,\n#saqIntroTitleText{\n  white-space:pre-wrap;\n}\n\n.ols-video-scene{\n  width:100%;\n  height:100%;\n  display:flex;\n  justify-content:center;\n  align-items:center;\n  opacity:0;\n  visibility:hidden;\n}\n\n.ols-video-scene.show{\n  visibility:visible;\n  animation:olsVideoSceneIn 1s ease forwards;\n}\n\n@keyframes olsVideoSceneIn{to{opacity:1;}}\n\n.ols-video-scale-wrap{\n  width:calc(var(--ols-video-screen-w) * 1px);\n  height:calc(var(--ols-video-screen-h) * 1px);\n  transform:scale(var(--ols-video-screen-scale));\n  transform-origin:center center;\n  display:flex;\n  justify-content:center;\n  align-items:center;\n}\n\n.ols-video-card{\n  width:1180px;\n  height:664px;\n  border-radius:28px;\n  overflow:hidden;\n  background:#1C244B;\n  box-shadow:0 28px 80px rgba(28,36,75,0.28);\n  transform:translateY(24px) scale(0.96);\n  opacity:0;\n}\n\n.ols-video-scene.show .ols-video-card{\n  animation:olsVideoCardIn 1s cubic-bezier(.18,.89,.32,1.12) forwards;\n  animation-delay:0.2s;\n}\n\n@keyframes olsVideoCardIn{\n  to{\n    transform:translateY(0) scale(1);\n    opacity:1;\n  }\n}\n\n.ols-video-card video{\n  display:block;\n  width:100%;\n  height:100%;\n  aspect-ratio:16 \/ 9;\n  object-fit:cover;\n  border:0;\n}\n\n.ols-mcq-scale-wrap,\n.ols-saq-scale-wrap{\n  width:calc(var(--ols-mcq-screen-w) * 1px);\n  height:calc(var(--ols-mcq-screen-h) * 1px);\n  transform:scale(var(--ols-mcq-screen-scale));\n  transform-origin:center center;\n  display:flex;\n  justify-content:center;\n  align-items:flex-start;\n}\n\n.ols-saq-scale-wrap{\n  width:calc(var(--ols-saq-screen-w) * 1px);\n  height:calc(var(--ols-saq-screen-h) * 1px);\n  transform:scale(var(--ols-saq-screen-scale));\n}\n\n.ols-mcq-screen{\n  width:1360px;\n  height:1130px;\n  border-radius:22px;\n  overflow:hidden;\n  background:#eaf0ff;\n  box-shadow:0 26px 70px rgba(28,36,75,0.22);\n  opacity:0;\n  transform:translateY(24px) scale(0.96);\n}\n\n.ols-mcq-screen.show{\n  animation:olsMcqScreenEnter 1s ease forwards;\n}\n\n@keyframes olsMcqScreenEnter{\n  from{opacity:0;transform:translateY(24px) scale(0.96);}\n  to{opacity:1;transform:translateY(0) scale(1);}\n}\n\n.mcq-question-area{\n  background:#eaf0ff;\n  padding:28px 30px 30px;\n  position:relative;\n  height:610px;\n}\n\n.mcq-question-lead{\n  margin:0 0 14px;\n  font-size:24px;\n  line-height:1.35;\n  color:#111827;\n}\n\n.mcq-ionic-table{\n  border-collapse:collapse;\n  width:500px;\n  margin-bottom:8px;\n  font-size:21px;\n  color:#111827;\n}\n\n.mcq-ionic-table th,\n.mcq-ionic-table td{\n  border:1.5px solid #c9ced8;\n  padding:12px 18px;\n  text-align:center;\n}\n\n.mcq-ionic-table th{\n  background:#f2f2f2;\n  font-weight:700;\n}\n\n.mcq-ionic-table td{\n  background:#eaf0ff;\n}\n\n.mcq-question-main{\n  margin:6px 0 28px;\n  font-size:24px;\n  line-height:1.35;\n  color:#111827;\n}\n\n.mcq-options-wrap{\n  display:flex;\n  flex-direction:column;\n  gap:17px;\n  max-width:1200px;\n}\n\n.mcq-option-row{\n  display:flex;\n  align-items:center;\n  min-height:34px;\n  position:relative;\n}\n\n.mcq-radio{\n  width:28px;\n  height:28px;\n  border-radius:50%;\n  border:2px solid #6b7280;\n  margin-right:16px;\n  background:transparent;\n  position:relative;\n  flex:0 0 auto;\n}\n\n.mcq-radio::after{\n  content:\"\";\n  position:absolute;\n  inset:5px;\n  border-radius:50%;\n  background:#6b7280;\n  opacity:0;\n  transform:scale(0.4);\n  transition:opacity 0.25s ease,transform 0.25s ease;\n}\n\n.mcq-option-row.selected .mcq-radio::after{\n  opacity:1;\n  transform:scale(1);\n}\n\n.mcq-radio-ripple{\n  position:absolute;\n  left:14px;\n  top:50%;\n  width:28px;\n  height:28px;\n  border-radius:50%;\n  border:2px solid rgba(28,36,75,0.28);\n  transform:translate(-50%,-50%) scale(1);\n  opacity:0;\n  pointer-events:none;\n}\n\n.mcq-option-row.clicking .mcq-radio-ripple{\n  animation:mcqRipple 0.75s ease forwards;\n}\n\n@keyframes mcqRipple{\n  0%{opacity:0.65;transform:translate(-50%,-50%) scale(1);}\n  100%{opacity:0;transform:translate(-50%,-50%) scale(2.5);}\n}\n\n.mcq-option-label{\n  font-size:23px;\n  color:#111827;\n}\n\n.mcq-specific-feedback{\n  display:inline-flex;\n  align-items:center;\n  margin-left:18px;\n  min-height:38px;\n  opacity:0;\n  transform:translateX(-8px);\n}\n\n.mcq-specific-feedback.show{\n  opacity:1;\n  transform:translateX(0);\n  transition:opacity 0.35s ease,transform 0.35s ease;\n}\n\n.mcq-cross-icon{\n  width:26px;\n  height:26px;\n  border-radius:50%;\n  border:2px solid #d83255;\n  color:#d83255;\n  display:inline-flex;\n  justify-content:center;\n  align-items:center;\n  font-size:18px;\n  font-weight:700;\n  margin-right:12px;\n  opacity:0;\n  transform:scale(0.4);\n}\n\n.mcq-cross-icon.show{\n  animation:mcqCrossPop 0.35s ease forwards;\n}\n\n@keyframes mcqCrossPop{\n  70%{opacity:1;transform:scale(1.18);}\n  100%{opacity:1;transform:scale(1);}\n}\n\n.mcq-specific-feedback-text{\n  display:inline-block;\n  background:#fff4b8;\n  color:#111827;\n  padding:8px 16px;\n  font-size:22px;\n  line-height:1.35;\n  min-width:850px;\n  min-height:44px;\n}\n\n.mcq-submit-button{\n  position:absolute;\n  right:34px;\n  bottom:30px;\n  border:0;\n  border-radius:999px;\n  background:#1C244B;\n  color:#ffffff;\n  padding:14px 28px;\n  font-size:18px;\n  font-weight:600;\n  box-shadow:0 14px 32px rgba(28,36,75,0.25);\n  cursor:default;\n  transition:transform 0.2s ease,box-shadow 0.2s ease,background 0.2s ease;\n}\n\n.mcq-submit-button.clicked{\n  transform:translateY(2px) scale(0.97);\n  background:#26315f;\n  box-shadow:0 7px 18px rgba(28,36,75,0.22);\n}\n\n.mcq-general-feedback{\n  height:520px;\n  background:#fff3c9;\n  color:#8a6a00;\n  padding:26px 30px 28px;\n  font-size:23px;\n  line-height:1.34;\n  opacity:0;\n  transform:translateY(20px);\n  transition:opacity 0.7s ease,transform 0.7s ease;\n  overflow:hidden;\n}\n\n.mcq-general-feedback.show{\n  opacity:1;\n  transform:translateY(0);\n}\n\n#mcqGeneralText{\n  white-space:pre-wrap;\n}\n\n.mcq-specific-cursor{background:#111827;}\n.mcq-general-cursor{background:#8a6a00;}\n\n.ols-saq-screen{\n  width:1360px;\n  height:965px;\n  border-radius:22px;\n  overflow:hidden;\n  background:#eaf0ff;\n  box-shadow:0 26px 70px rgba(28,36,75,0.22);\n  opacity:0;\n  transform:translateY(24px) scale(0.96);\n}\n\n.ols-saq-screen.show{\n  animation:olsSaqScreenEnter 1s ease forwards;\n}\n\n@keyframes olsSaqScreenEnter{\n  from{opacity:0;transform:translateY(24px) scale(0.96);}\n  to{opacity:1;transform:translateY(0) scale(1);}\n}\n\n.saq-question-area{\n  height:335px;\n  background:#eaf0ff;\n  padding:30px 40px 32px;\n}\n\n.saq-question-text{\n  font-size:25px;\n  line-height:1.42;\n  color:#111827;\n  margin-bottom:22px;\n}\n\n.saq-student-box{\n  height:195px;\n  background:#f3f4f6;\n  border:2px solid #cfd6e3;\n  border-radius:8px;\n  padding:23px 26px;\n  font-size:24px;\n  line-height:1.55;\n  color:#4b5563;\n  position:relative;\n  overflow:hidden;\n}\n\n.saq-teacher-feedback{\n  height:630px;\n  background:#dff3e6;\n  color:#075f3b;\n  padding:28px 40px 30px;\n  font-size:23px;\n  line-height:1.47;\n  opacity:0;\n  transform:translateY(20px);\n  transition:opacity 0.7s ease,transform 0.7s ease;\n  overflow:hidden;\n}\n\n.saq-teacher-feedback.show{\n  opacity:1;\n  transform:translateY(0);\n}\n\n#saqTeacherText{\n  white-space:pre-wrap;\n}\n\n.saq-teacher-cursor{\n  background:#075f3b;\n}\n\n@media(max-width:900px){\n  .ols-video-title,\n  .ols-mcq-intro-title,\n  .ols-saq-intro-title{\n    font-size:clamp(42px,11vw,78px);\n    line-height:1.12;\n  }\n\n  .ols-title-cursor{\n    width:4px;\n    margin-left:6px;\n  }\n\n  .ols-video-card{\n    border-radius:20px;\n  }\n}\n<\/style>\n<\/head>\n\n<body>\n<div class=\"ols-combined-stage\">\n\n  <section id=\"sceneVideo\" class=\"ols-scene active\">\n    <div class=\"ols-video-stage\">\n      <div id=\"videoTitleScreen\" class=\"ols-video-title-screen\">\n        <div class=\"ols-video-title-wrap\">\n          <h1 class=\"ols-video-title\">\n            <span id=\"videoTitleText\"><\/span><span id=\"videoTitleCursor\" class=\"ols-title-cursor\"><\/span>\n          <\/h1>\n        <\/div>\n      <\/div>\n\n      <section id=\"videoScene\" class=\"ols-video-scene\">\n        <div class=\"ols-video-scale-wrap\">\n          <div class=\"ols-video-card\">\n            <video\n              id=\"lessonVideo\"\n              src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Virtual-Lesson.mp4\"\n              muted\n              playsinline\n              preload=\"auto\">\n            <\/video>\n          <\/div>\n        <\/div>\n      <\/section>\n    <\/div>\n  <\/section>\n\n  <section id=\"sceneMcq\" class=\"ols-scene\">\n    <div class=\"ols-mcq-stage\">\n      <div id=\"mcqIntroScreen\" class=\"ols-mcq-intro-screen\">\n        <div class=\"ols-mcq-intro-title-wrap\">\n          <h1 class=\"ols-mcq-intro-title\">\n            <span id=\"mcqIntroTitleText\"><\/span><span id=\"mcqIntroTitleCursor\" class=\"ols-title-cursor\"><\/span>\n          <\/h1>\n        <\/div>\n      <\/div>\n\n      <div class=\"ols-mcq-scale-wrap\">\n        <main id=\"mcqScreen\" class=\"ols-mcq-screen\">\n          <section class=\"mcq-question-area\">\n            <p class=\"mcq-question-lead\">Some ionic radii are shown.<\/p>\n\n            <table class=\"mcq-ionic-table\">\n              <thead>\n                <tr>\n                  <th>Ion<\/th>\n                  <th>Ionic radius \/ nm<\/th>\n                <\/tr>\n              <\/thead>\n              <tbody>\n                <tr><td>Na<sup>+<\/sup><\/td><td>0.102<\/td><\/tr>\n                <tr><td>K<sup>+<\/sup><\/td><td>0.138<\/td><\/tr>\n                <tr><td>F<sup>\u2212<\/sup><\/td><td>0.133<\/td><\/tr>\n                <tr><td>Cl<sup>\u2212<\/sup><\/td><td>0.180<\/td><\/tr>\n              <\/tbody>\n            <\/table>\n\n            <p class=\"mcq-question-main\">Which compound has the strongest ionic bonding?<\/p>\n\n            <div class=\"mcq-options-wrap\">\n              <div id=\"mcqWrongOption\" class=\"mcq-option-row\">\n                <span class=\"mcq-radio\"><\/span>\n                <span class=\"mcq-radio-ripple\"><\/span>\n                <span class=\"mcq-option-label\">sodium chloride<\/span>\n\n                <span id=\"mcqSpecificFeedback\" class=\"mcq-specific-feedback\">\n                  <span id=\"mcqCrossIcon\" class=\"mcq-cross-icon\">\u00d7<\/span>\n                  <span class=\"mcq-specific-feedback-text\">\n                    <span id=\"mcqSpecificText\"><\/span><span id=\"mcqSpecificCursor\" class=\"cursor mcq-specific-cursor\" style=\"display:none;\"><\/span>\n                  <\/span>\n                <\/span>\n              <\/div>\n\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>\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>\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>\n            <\/div>\n\n            <button id=\"mcqSubmitButton\" class=\"mcq-submit-button\">Submit answer<\/button>\n          <\/section>\n\n          <section id=\"mcqGeneralFeedback\" class=\"mcq-general-feedback\">\n            <span id=\"mcqGeneralText\"><\/span><span id=\"mcqGeneralCursor\" class=\"cursor mcq-general-cursor\" style=\"display:none;\"><\/span>\n          <\/section>\n        <\/main>\n      <\/div>\n    <\/div>\n  <\/section>\n\n  <section id=\"sceneSaq\" class=\"ols-scene\">\n    <div class=\"ols-saq-stage\">\n      <div id=\"saqIntro\" class=\"ols-saq-intro\">\n        <div class=\"ols-saq-intro-title-wrap\">\n          <h1 class=\"ols-saq-intro-title\">\n            <span id=\"saqIntroTitleText\"><\/span><span id=\"saqIntroTitleCursor\" class=\"ols-title-cursor\"><\/span>\n          <\/h1>\n        <\/div>\n      <\/div>\n\n      <div class=\"ols-saq-scale-wrap\">\n        <main id=\"saqScreen\" class=\"ols-saq-screen\">\n          <section class=\"saq-question-area\">\n            <div class=\"saq-question-text\">\n              <strong>(ii)<\/strong>&nbsp;&nbsp; Melting temperature depends on the strength of metallic bonding.<br>\n              Explain why the metallic bonding in magnesium is much stronger than that in sodium.\n            <\/div>\n\n            <div class=\"saq-student-box\">\n              <span id=\"saqStudentText\"><\/span><span id=\"saqStudentCursor\" class=\"cursor\"><\/span>\n            <\/div>\n          <\/section>\n\n          <section id=\"saqTeacherFeedback\" class=\"saq-teacher-feedback\">\n            <span id=\"saqTeacherText\"><\/span><span id=\"saqTeacherCursor\" class=\"cursor saq-teacher-cursor\" style=\"display:none;\"><\/span>\n          <\/section>\n        <\/main>\n      <\/div>\n    <\/div>\n  <\/section>\n\n<\/div>\n\n<script>\n(function(){\n  const nativeSetTimeout=window.setTimeout.bind(window);\n  const nativeClearTimeout=window.clearTimeout.bind(window);\n  let nextTimerId=1;\n  let paused=false;\n  const timers=new Map();\n\n  function runTimer(timerId){\n    const timer=timers.get(timerId);\n\n    if(!timer || timer.cleared){\n      return;\n    }\n\n    timers.delete(timerId);\n    timer.callback();\n  }\n\n  window.setTimeout=function(callback,delay){\n    const timerId=nextTimerId++;\n    const safeDelay=Math.max(0,Number(delay) || 0);\n\n    const timer={\n      callback:callback,\n      delay:safeDelay,\n      remaining:safeDelay,\n      startedAt:Date.now(),\n      nativeId:null,\n      cleared:false\n    };\n\n    if(paused){\n      timer.startedAt=null;\n    }else{\n      timer.nativeId=nativeSetTimeout(function(){\n        runTimer(timerId);\n      },safeDelay);\n    }\n\n    timers.set(timerId,timer);\n    return timerId;\n  };\n\n  window.clearTimeout=function(timerId){\n    const timer=timers.get(timerId);\n\n    if(timer){\n      timer.cleared=true;\n\n      if(timer.nativeId!==null){\n        nativeClearTimeout(timer.nativeId);\n      }\n\n      timers.delete(timerId);\n      return;\n    }\n\n    nativeClearTimeout(timerId);\n  };\n\n  function pauseVideos(){\n    document.querySelectorAll(\"video\").forEach(function(video){\n      if(!video.paused && !video.ended){\n        video.dataset.olsWasPlaying=\"1\";\n        video.pause();\n      }\n    });\n  }\n\n  function resumeVideos(){\n    document.querySelectorAll(\"video\").forEach(function(video){\n      if(video.dataset.olsWasPlaying===\"1\"){\n        delete video.dataset.olsWasPlaying;\n\n        const playPromise=video.play();\n\n        if(playPromise!==undefined){\n          playPromise.catch(function(){});\n        }\n      }\n    });\n  }\n\n  function pauseAnimation(){\n    if(paused){\n      return \"paused\";\n    }\n\n    paused=true;\n    document.documentElement.classList.add(\"ols-animation-paused\");\n\n    timers.forEach(function(timer){\n      if(timer.nativeId!==null){\n        nativeClearTimeout(timer.nativeId);\n        timer.nativeId=null;\n      }\n\n      if(timer.startedAt!==null){\n        timer.remaining=Math.max(0,timer.delay-(Date.now()-timer.startedAt));\n        timer.startedAt=null;\n      }\n    });\n\n    pauseVideos();\n    return \"paused\";\n  }\n\n  function resumeAnimation(){\n    if(!paused){\n      return \"playing\";\n    }\n\n    paused=false;\n    document.documentElement.classList.remove(\"ols-animation-paused\");\n\n    timers.forEach(function(timer,timerId){\n      timer.startedAt=Date.now();\n      timer.delay=timer.remaining;\n      timer.nativeId=nativeSetTimeout(function(){\n        runTimer(timerId);\n      },timer.remaining);\n    });\n\n    resumeVideos();\n    return \"playing\";\n  }\n\n  window.olsToggleAnimationPause=function(){\n    if(paused){\n      return resumeAnimation();\n    }\n\n    return pauseAnimation();\n  };\n\n  window.olsPauseAnimation=pauseAnimation;\n  window.olsResumeAnimation=resumeAnimation;\n})();\n\nfunction typeWriter(target,text,speed,callback){\n  let i=0;\n\n  function typing(){\n    if(i<text.length){\n      const char=text.charAt(i);\n      target.textContent+=char;\n      i++;\n\n      let delay=speed;\n\n      if(char===\".\"){delay=speed*5;}\n      if(char===\",\"){delay=speed*2.5;}\n      if(char===\"\\n\"){delay=speed*4;}\n\n      setTimeout(typing,delay);\n    }else{\n      if(callback){callback();}\n    }\n  }\n\n  typing();\n}\n\nfunction switchScene(currentScene,nextScene,callback){\n  currentScene.classList.add(\"fade-out\");\n\n  setTimeout(function(){\n    currentScene.classList.remove(\"active\");\n    currentScene.classList.remove(\"fade-out\");\n    nextScene.classList.add(\"active\");\n\n    if(callback){callback();}\n  },850);\n}\n\nfunction fitVideoScreen(){\n  const baseWidth=1180;\n  const baseHeight=664;\n  const safePadding=24;\n  const availableWidth=window.innerWidth-safePadding;\n  const availableHeight=window.innerHeight-safePadding;\n  const scaleByWidth=availableWidth\/baseWidth;\n  const scaleByHeight=availableHeight\/baseHeight;\n  const finalScale=Math.min(scaleByWidth,scaleByHeight,1);\n  document.documentElement.style.setProperty(\"--ols-video-screen-scale\",finalScale.toFixed(4));\n}\n\nfunction fitMcqScreen(){\n  const baseWidth=1360;\n  const baseHeight=1130;\n  const safePadding=24;\n  const availableWidth=window.innerWidth-safePadding;\n  const availableHeight=window.innerHeight-safePadding;\n  const scaleByWidth=availableWidth\/baseWidth;\n  const scaleByHeight=availableHeight\/baseHeight;\n  const finalScale=Math.min(scaleByWidth,scaleByHeight,1);\n  document.documentElement.style.setProperty(\"--ols-mcq-screen-scale\",finalScale.toFixed(4));\n}\n\nfunction fitSaqScreen(){\n  const baseWidth=1360;\n  const baseHeight=965;\n  const safePadding=24;\n  const availableWidth=window.innerWidth-safePadding;\n  const availableHeight=window.innerHeight-safePadding;\n  const scaleByWidth=availableWidth\/baseWidth;\n  const scaleByHeight=availableHeight\/baseHeight;\n  const finalScale=Math.min(scaleByWidth,scaleByHeight,1);\n  document.documentElement.style.setProperty(\"--ols-saq-screen-scale\",finalScale.toFixed(4));\n}\n\nfunction fitAllScreens(){\n  fitVideoScreen();\n  fitMcqScreen();\n  fitSaqScreen();\n}\n\nwindow.addEventListener(\"resize\",fitAllScreens);\nwindow.addEventListener(\"orientationchange\",fitAllScreens);\nfitAllScreens();\n\nconst sceneVideo=document.getElementById(\"sceneVideo\");\nconst sceneMcq=document.getElementById(\"sceneMcq\");\nconst sceneSaq=document.getElementById(\"sceneSaq\");\n\nconst videoTitle=\"Online Chemistry Lessons\";\nconst videoTitleText=document.getElementById(\"videoTitleText\");\nconst videoTitleCursor=document.getElementById(\"videoTitleCursor\");\nconst videoTitleScreen=document.getElementById(\"videoTitleScreen\");\nconst videoScene=document.getElementById(\"videoScene\");\nconst lessonVideo=document.getElementById(\"lessonVideo\");\n\nlet videoFallbackTimer=null;\nlet videoSceneComplete=false;\n\nfunction playLessonVideo(){\n  lessonVideo.muted=true;\n  lessonVideo.currentTime=0;\n\n  const playPromise=lessonVideo.play();\n\n  if(playPromise!==undefined){\n    playPromise.catch(function(){\n      lessonVideo.muted=true;\n    });\n  }\n}\n\nfunction completeVideoScene(){\n  if(videoSceneComplete){return;}\n\n  videoSceneComplete=true;\n\n  if(videoFallbackTimer){\n    clearTimeout(videoFallbackTimer);\n  }\n\n  lessonVideo.pause();\n\n  setTimeout(function(){\n    switchScene(sceneVideo,sceneMcq,function(){\n      startMcqIntro();\n    });\n  },1400);\n}\n\nlessonVideo.addEventListener(\"ended\",function(){\n  lessonVideo.pause();\n  completeVideoScene();\n});\n\nfunction startVideoSection(){\n  fitVideoScreen();\n\n  setTimeout(function(){\n    typeWriter(videoTitleText,videoTitle,44,function(){\n      setTimeout(function(){\n        videoTitleCursor.style.display=\"none\";\n\n        setTimeout(function(){\n          videoTitleScreen.classList.add(\"hide\");\n\n          setTimeout(function(){\n            videoScene.classList.add(\"show\");\n\n            setTimeout(function(){\n              playLessonVideo();\n\n              videoFallbackTimer=setTimeout(function(){\n                completeVideoScene();\n              },45000);\n            },600);\n          },850);\n        },3000);\n      },250);\n    });\n  },700);\n}\n\nconst mcqIntroTitle=\"Multiple Choice Question Bank\";\nconst mcqSpecificFeedbackText=\"Na\u207a is small, but Cl\u207b is larger than F\u207b, so the ionic bonding is weaker than in NaF.\";\nconst mcqGeneralFeedbackText=\n\"Your answer is incorrect.\\n\\n\"+\n\"To determine which compound has the strongest ionic bonding, recall the key principle:\\n\\n\"+\n\"\u2022 Ionic bond strength increases when ionic radii are small, because the ions can get closer together.\\n\"+\n\"\u2022 Smaller ions \u2192 stronger electrostatic attraction \u2192 stronger ionic lattice.\\n\"+\n\"\u2022 Na\u207a (0.102 nm) is smaller than K\u207a (0.138 nm).\\n\"+\n\"\u2022 F\u207b (0.133 nm) is smaller than Cl\u207b (0.180 nm).\\n\\n\"+\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\"+\n\"The correct answer is: sodium fluoride\";\n\nconst mcqIntroScreen=document.getElementById(\"mcqIntroScreen\");\nconst mcqIntroTitleText=document.getElementById(\"mcqIntroTitleText\");\nconst mcqIntroTitleCursor=document.getElementById(\"mcqIntroTitleCursor\");\nconst mcqScreen=document.getElementById(\"mcqScreen\");\nconst mcqWrongOption=document.getElementById(\"mcqWrongOption\");\nconst mcqSubmitButton=document.getElementById(\"mcqSubmitButton\");\nconst mcqSpecificFeedback=document.getElementById(\"mcqSpecificFeedback\");\nconst mcqCrossIcon=document.getElementById(\"mcqCrossIcon\");\nconst mcqSpecificText=document.getElementById(\"mcqSpecificText\");\nconst mcqSpecificCursor=document.getElementById(\"mcqSpecificCursor\");\nconst mcqGeneralFeedback=document.getElementById(\"mcqGeneralFeedback\");\nconst mcqGeneralText=document.getElementById(\"mcqGeneralText\");\nconst mcqGeneralCursor=document.getElementById(\"mcqGeneralCursor\");\n\nfunction selectMcqWrongOption(){\n  mcqWrongOption.classList.add(\"clicking\");\n\n  setTimeout(function(){\n    mcqWrongOption.classList.add(\"selected\");\n  },220);\n\n  setTimeout(function(){\n    mcqWrongOption.classList.remove(\"clicking\");\n  },850);\n}\n\nfunction clickMcqSubmit(){\n  mcqSubmitButton.classList.add(\"clicked\");\n\n  setTimeout(function(){\n    mcqSubmitButton.classList.remove(\"clicked\");\n  },240);\n}\n\nfunction showMcqSpecificFeedback(){\n  mcqSpecificFeedback.classList.add(\"show\");\n\n  setTimeout(function(){\n    mcqCrossIcon.classList.add(\"show\");\n  },180);\n\n  setTimeout(function(){\n    mcqSpecificCursor.style.display=\"inline-block\";\n\n    typeWriter(mcqSpecificText,mcqSpecificFeedbackText,12,function(){\n      mcqSpecificCursor.style.display=\"none\";\n\n      setTimeout(function(){\n        showMcqGeneralFeedback();\n      },650);\n    });\n  },560);\n}\n\nfunction showMcqGeneralFeedback(){\n  mcqGeneralFeedback.classList.add(\"show\");\n\n  setTimeout(function(){\n    mcqGeneralCursor.style.display=\"inline-block\";\n\n    typeWriter(mcqGeneralText,mcqGeneralFeedbackText,8,function(){\n      mcqGeneralCursor.style.display=\"none\";\n\n      setTimeout(function(){\n        switchScene(sceneMcq,sceneSaq,function(){\n          startSaqIntro();\n        });\n      },2600);\n    });\n  },600);\n}\n\nfunction startMcqAnimation(){\n  fitMcqScreen();\n  mcqScreen.classList.add(\"show\");\n\n  setTimeout(function(){\n    selectMcqWrongOption();\n\n    setTimeout(function(){\n      clickMcqSubmit();\n\n      setTimeout(function(){\n        showMcqSpecificFeedback();\n      },620);\n    },1150);\n  },1300);\n}\n\nfunction startMcqIntro(){\n  fitMcqScreen();\n\n  setTimeout(function(){\n    typeWriter(mcqIntroTitleText,mcqIntroTitle,44,function(){\n      setTimeout(function(){\n        mcqIntroTitleCursor.style.display=\"none\";\n\n        setTimeout(function(){\n          mcqIntroScreen.classList.add(\"hide\");\n\n          setTimeout(function(){\n            startMcqAnimation();\n          },850);\n        },3000);\n      },250);\n    });\n  },700);\n}\n\nconst saqIntroTitle=\"Chemistry Specialist\\nMarked Exam Feedback\";\nconst saqStudentAnswer=\"Magnesium has stronger metallic bonding because it has more atoms packed together and melts at a higher temperature than sodium.\";\nconst saqTeacherFeedbackText=\n\"Comment:\\n\"+\n\"This answer is not correct. Melting temperature is a result of bonding strength, not the cause of it.\\n\\n\"+\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\"+\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\"+\n\"Next time, include:\\n\"+\n\"\u2022 Ion charge: magnesium forms Mg\u00b2\u207a, sodium forms Na\u207a \u2713\\n\"+\n\"\u2022 Delocalised electrons: magnesium provides more electrons to the sea \u2713\\n\"+\n\"\u2022 Charge density: smaller, more highly charged ions create stronger attraction \u2713\\n\\n\"+\n\"You were close. Focus on explaining bonding in terms of charge and electron density rather than physical properties like melting point.\";\n\nconst saqIntro=document.getElementById(\"saqIntro\");\nconst saqIntroTitleText=document.getElementById(\"saqIntroTitleText\");\nconst saqIntroTitleCursor=document.getElementById(\"saqIntroTitleCursor\");\nconst saqStudentText=document.getElementById(\"saqStudentText\");\nconst saqTeacherText=document.getElementById(\"saqTeacherText\");\nconst saqStudentCursor=document.getElementById(\"saqStudentCursor\");\nconst saqTeacherCursor=document.getElementById(\"saqTeacherCursor\");\nconst saqFeedbackBox=document.getElementById(\"saqTeacherFeedback\");\nconst saqScreen=document.getElementById(\"saqScreen\");\n\nfunction startSaqFeedbackAnimation(){\n  fitSaqScreen();\n  saqScreen.classList.add(\"show\");\n\n  setTimeout(function(){\n    typeWriter(saqStudentText,saqStudentAnswer,27,function(){\n      saqStudentCursor.style.display=\"none\";\n\n      setTimeout(function(){\n        saqFeedbackBox.classList.add(\"show\");\n        saqTeacherCursor.style.display=\"inline-block\";\n\n        typeWriter(saqTeacherText,saqTeacherFeedbackText,10,function(){\n          saqTeacherCursor.style.display=\"none\";\n        });\n      },650);\n    });\n  },850);\n}\n\nfunction startSaqIntro(){\n  fitSaqScreen();\n\n  setTimeout(function(){\n    typeWriter(saqIntroTitleText,saqIntroTitle,44,function(){\n      setTimeout(function(){\n        saqIntroTitleCursor.style.display=\"none\";\n\n        setTimeout(function(){\n          saqIntro.classList.add(\"hide\");\n\n          setTimeout(function(){\n            startSaqFeedbackAnimation();\n          },850);\n        },3000);\n      },250);\n    });\n  },700);\n}\n\nstartVideoSection();\n<\/script>\n<\/body>\n<\/html>\n  <\/template>\n\n  <script>\n    (function(){\n      var ctaRoot = document.getElementById(\"olsCourseCtaIonicMetallic001\");\n\n      if (!ctaRoot || ctaRoot.dataset.olsAnimationReady === \"1\") {\n        return;\n      }\n\n      ctaRoot.dataset.olsAnimationReady = \"1\";\n\n      var startButton = ctaRoot.querySelector(\"#olsCourseAnimationStart001\");\n      var pauseButton = ctaRoot.querySelector(\"#olsCourseAnimationPause001\");\n      var iframe = ctaRoot.querySelector(\"#olsCourseAnimationFrame001\");\n      var template = ctaRoot.querySelector(\"#olsCourseAnimationTemplate001\");\n\n      if (!startButton || !pauseButton || !iframe || !template) {\n        return;\n      }\n\n      function loadAnimationIntoFrame(){\n        var animationHtml = template.innerHTML;\n\n        try {\n          iframe.removeAttribute(\"srcdoc\");\n          iframe.setAttribute(\"src\", \"about:blank\");\n\n          var frameDocument = iframe.contentDocument || (iframe.contentWindow && iframe.contentWindow.document);\n\n          if (!frameDocument) {\n            iframe.setAttribute(\"srcdoc\", animationHtml);\n            return;\n          }\n\n          frameDocument.open();\n          frameDocument.write(animationHtml);\n          frameDocument.close();\n        } catch (error) {\n          iframe.setAttribute(\"srcdoc\", animationHtml);\n        }\n      }\n\n      startButton.addEventListener(\"click\", function(){\n        loadAnimationIntoFrame();\n        startButton.classList.add(\"is-hidden\");\n        pauseButton.classList.add(\"is-visible\");\n        pauseButton.textContent = \"Pause\";\n        pauseButton.setAttribute(\"aria-label\", \"Pause course preview animation\");\n      });\n\n      pauseButton.addEventListener(\"click\", function(){\n        if (!iframe.contentWindow || typeof iframe.contentWindow.olsToggleAnimationPause !== \"function\") {\n          return;\n        }\n\n        var state = iframe.contentWindow.olsToggleAnimationPause();\n\n        if (state === \"paused\") {\n          pauseButton.textContent = \"Resume\";\n          pauseButton.setAttribute(\"aria-label\", \"Resume course preview animation\");\n        } else {\n          pauseButton.textContent = \"Pause\";\n          pauseButton.setAttribute(\"aria-label\", \"Pause course preview animation\");\n        }\n      });\n    })();\n  <\/script>\n<\/section>\n\n      <section class=\"ols-related-card\">\n        <h2>Related Bonding &amp; Structure Revision Notes<\/h2>\n        <p>Continue through Topic 3 by linking ionic bonding to polarisation, ionic properties and covalent bonding.<\/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\/edexcel-international\/\">Polarisation of Ions<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/\">Physical Properties of Ionic Compounds<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/\">Covalent Bonding &amp; Structure<\/a>\n        <\/div>\n      <\/section>\n\n    \n\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    <\/main>\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@graph\": [\n    {\n      \"@type\": \"WebPage\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/structure-types\/#webpage\",\n      \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/structure-types\/\",\n      \"name\": \"Ionic Bonding & Structure - Edexcel International A Level Chemistry Revision Notes\",\n      \"description\": \"Edexcel International A Level Chemistry Topic 3 revision notes comparing giant ionic, giant metallic, giant covalent and simple molecular lattices and their physical properties.\",\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\": \"Ionic bonding\"\n        },\n        {\n          \"@type\": \"Thing\",\n          \"name\": \"Giant ionic lattice\"\n        },\n        {\n          \"@type\": \"Thing\",\n          \"name\": \"Ionic radii\"\n        },\n        {\n          \"@type\": \"Thing\",\n          \"name\": \"Edexcel International A Level Chemistry\"\n        }\n      ],\n      \"author\": {\n        \"@type\": \"Person\",\n        \"name\": \"Dr. Mohammed Al-Fatah\",\n        \"url\": \"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\"\n      },\n      \"publisher\": {\n        \"@type\": \"Organization\",\n        \"name\": \"Online Learning System\",\n        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/\"\n      }\n    },\n    {\n      \"@type\": \"BreadcrumbList\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/#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\": \"Edexcel International\",\n          \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/\"\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 4,\n          \"name\": \"Topic 3 Bonding and Structure\",\n          \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/\"\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 5,\n          \"name\": \"Structure Types\",\n          \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-3-bonding-structure\/structure-types\/\"\n        }\n      ]\n    },\n    {\n      \"@type\": \"Course\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/organic-chemistry-alkanes-topic-4ab-edexcel-international\/#course\",\n      \"name\": \"Organic Chemistry and Alkanes Topic 4A\/B Edexcel International A Level Chemistry Course\",\n      \"description\": \"A guided Topic 4A\/B Organic Chemistry and Alkanes course with video teaching, MCQ practice, teacher-marked SAQs and specification-based progress tracking.\",\n      \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/organic-chemistry-alkanes-topic-4ab-edexcel-international\/\",\n      \"provider\": {\n        \"@type\": \"Organization\",\n        \"name\": \"Online Learning System\",\n        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/\"\n      }\n    }\n  ]\n}\n<\/script>\n<\/section>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Revision Notes \/ A Level Chemistry \/ Edexcel International \/ Topic 3 Bonding and Structure \/ Structure Types Structure Types A concise revision guide to the four types of solid lattice, giant ionic, giant metallic, giant covalent and simple molecular: which particles they contain, what holds them together, and how that decides melting point, conductivity, [&hellip;]<\/p>\n","protected":false},"author":12,"featured_media":0,"parent":3740,"menu_order":6,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-7766","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/7766","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/comments?post=7766"}],"version-history":[{"count":0,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/7766\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/3740"}],"wp:attachment":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/media?parent=7766"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}