{"id":4525,"date":"2026-05-28T06:05:29","date_gmt":"2026-05-28T05:05:29","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/"},"modified":"2026-05-30T09:10:37","modified_gmt":"2026-05-30T08:10:37","slug":"trends-in-a-group","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/","title":{"rendered":"Trends in a Group"},"content":{"rendered":"\n<!--\n===============================================================================\nONLINE LEARNING SYSTEM COPYRIGHT NOTICE\n\u00a9 Online Learning System. All rights reserved.\n\nThis WordPress revision page HTML, CSS, content sequence, educational wording,\nlayout structure, schema structure and embedded design logic are protected\nintellectual property of Online Learning System.\n\nUnauthorised copying, redistribution, resale, modification, republication,\nscraping, extraction, derivative reuse, automated harvesting or removal of\ncopyright notices is strictly prohibited.\n\nBackend copyright marker:\nOLS-T1-IONISATION-TRENDS-IN-A-GROUP-REVISION-PAGE-9CH0-2026\n\nPage:\nTrends in a Group\nEdexcel A Level Chemistry (9CH0)\nPaper 1: Advanced Inorganic and Physical Chemistry\nTopic 1: Atomic Structure & The Periodic Table\n9CH0\/01\n===============================================================================\n-->\n\n<section class=\"ols-revision-page ols-trends-in-a-group-9ch0-page\" data-owner=\"Online Learning System\" data-copyright=\"\u00a9 Online Learning System. All rights reserved.\" data-rights=\"Unauthorised copying, redistribution, resale, modification, republication, scraping, extraction, derivative reuse or removal of copyright notices is prohibited.\">\n  <style>\n    \/*\n      \u00a9 Online Learning System. All rights reserved.\n      This CSS layout, page structure and educational design are protected.\n      Do not copy, scrape, republish, redistribute, resell or modify without permission.\n      Backend copyright marker: OLS-T1-IONISATION-TRENDS-IN-A-GROUP-REVISION-PAGE-9CH0-2026.\n    *\/\n\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      --gold: #c9973a;\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 * {\n      box-sizing: border-box;\n    }\n\n    .ols-revision-layout {\n\n    .ols-main {\n      min-width: 0;\n      max-width: 970px;\n    }\n\n    .ols-breadcrumbs {\n      display: flex;\n      flex-wrap: wrap;\n      gap: 8px;\n      margin: 10px 0 22px;\n      font-size: 15px;\n      color: var(--grey-text);\n    }\n\n    .ols-breadcrumbs a,\n    .ols-breadcrumbs span {\n      color: var(--grey-text);\n      text-decoration: none;\n      font-weight: 600;\n    }\n\n    .ols-breadcrumbs a:hover {\n      color: var(--blue);\n      text-decoration: underline;\n      text-underline-offset: 3px;\n    }\n\n    .ols-title-card,\n    .ols-note-card,\n    .ols-h5p-card,\n    .ols-related-card,\n    .ols-faq-card,\n    .ols-quicksnap-card {\n      background: #ffffff;\n      border: 1px solid var(--border);\n      border-radius: 28px;\n      box-shadow: var(--shadow);\n      padding: 34px;\n      margin-bottom: 24px;\n      overflow: hidden;\n    }\n\n    .ols-title-card {\n      background: linear-gradient(135deg, #ffffff 0%, #f8fbff 100%);\n    }\n\n    .ols-title-card h1 {\n      margin: 0 0 18px;\n      font-size: clamp(36px, 5vw, 58px);\n      line-height: 1.08;\n      font-weight: 800;\n      letter-spacing: -0.04em;\n      color: #111827;\n    }\n\n    .ols-page-intro {\n      font-size: 19px;\n      line-height: 1.7;\n      font-weight: 300;\n      color: var(--body-text);\n      margin: 0 0 22px;\n    }\n\n    .ols-badges {\n      display: flex;\n      flex-direction: column;\n      align-items: flex-start;\n      gap: 12px;\n      margin-bottom: 22px;\n    }\n\n    .ols-badge {\n      display: inline-flex;\n      align-items: center;\n      padding: 9px 14px;\n      border-radius: 999px;\n      background: #ffffff;\n      border: 1px solid var(--border);\n      font-size: 15px;\n      font-weight: 600;\n      color: var(--navy);\n    }\n\n    .ols-author {\n      display: flex;\n      align-items: center;\n      gap: 20px;\n      padding: 28px;\n      border-radius: 28px;\n      background: linear-gradient(135deg, #ffffff 0%, #f8fbff 100%);\n      border: 1px solid rgba(28,36,75,0.12);\n      box-shadow: 0 18px 45px rgba(28,36,75,0.10);\n      margin-top: 22px;\n    }\n\n    .ols-author-avatar-img {\n      width: 92px;\n      height: 92px;\n      border-radius: 50%;\n      object-fit: cover;\n      object-position: center;\n      flex-shrink: 0;\n      border: 4px solid #ffffff;\n      box-shadow: 0 14px 32px rgba(28,36,75,0.18), 0 0 0 1px rgba(28,36,75,0.10);\n      transition: transform 0.25s ease, box-shadow 0.25s ease;\n    }\n\n    .ols-author:hover .ols-author-avatar-img {\n      transform: scale(1.04);\n      box-shadow: 0 20px 42px rgba(28,36,75,0.22), 0 0 0 1px rgba(28,36,75,0.10);\n    }\n\n    .ols-author-content {\n      min-width: 0;\n    }\n\n    .ols-author-title {\n      margin: 0 0 4px;\n      font-size: clamp(24px,3vw,34px);\n      line-height: 1.15;\n      font-weight: 700;\n      color: var(--navy);\n      letter-spacing: -0.03em;\n    }\n\n    .ols-author-description {\n      margin: 0;\n      font-size: 17px;\n      line-height: 1.7;\n      font-weight: 300;\n      color: var(--grey-text);\n    }\n\n    .ols-linkedin-pill {\n      display: inline-flex;\n      align-items: center;\n      justify-content: center;\n      gap: 10px;\n      margin-top: 16px;\n      padding: 11px 18px;\n      border-radius: 999px;\n      background: linear-gradient(135deg,#0A66C2,#004182);\n      color: #ffffff;\n      text-decoration: none;\n      font-size: 14px;\n      line-height: 1;\n      font-weight: 700;\n      letter-spacing: 0.01em;\n      box-shadow: 0 10px 22px rgba(10,102,194,0.24);\n      position: relative;\n      overflow: hidden;\n      transition: transform 0.22s ease, box-shadow 0.22s ease;\n    }\n\n    .ols-linkedin-pill::before {\n      content: \"\";\n      position: absolute;\n      top: 0;\n      left: -120%;\n      width: 100%;\n      height: 100%;\n      background: linear-gradient(120deg, rgba(255,255,255,0) 0%, rgba(255,255,255,0.28) 50%, rgba(255,255,255,0) 100%);\n      transition: left 0.7s ease;\n    }\n\n    .ols-linkedin-pill:hover {\n      transform: translateY(-3px) scale(1.03);\n      box-shadow: 0 16px 34px rgba(10,102,194,0.34), 0 0 0 6px rgba(10,102,194,0.10);\n      color: #ffffff;\n    }\n\n    .ols-linkedin-pill:hover::before {\n      left: 120%;\n    }\n\n    .ols-linkedin-icon {\n      width: 18px;\n      height: 18px;\n      display: block;\n      flex-shrink: 0;\n    }\n\n    .ols-note-card.soft {\n      background: linear-gradient(135deg, #ffffff 0%, var(--soft-red) 100%);\n    }\n\n    .ols-note-card.purple {\n      background: linear-gradient(135deg, #ffffff 0%, var(--soft-purple) 100%);\n    }\n\n    .ols-note-card.orange {\n      background: linear-gradient(135deg, #ffffff 0%, var(--soft-orange) 100%);\n    }\n\n    .ols-note-title {\n      display: flex;\n      align-items: center;\n      gap: 14px;\n      margin-bottom: 20px;\n    }\n\n    .ols-note-icon {\n      width: 52px;\n      height: 52px;\n      border-radius: 16px;\n      background: var(--navy);\n      color: #ffffff;\n      display: grid;\n      place-items: center;\n      font-size: 24px;\n      font-weight: 800;\n      flex-shrink: 0;\n    }\n\n    .ols-note-title h2,\n    .ols-h5p-card h2,\n    .ols-related-card h2,\n    .ols-faq-card h2,\n    .ols-quicksnap-card h2,\n    .ols-infographic-title {\n      margin: 0;\n      font-size: clamp(28px, 3.5vw, 42px);\n      line-height: 1.15;\n      font-weight: 800;\n      color: #111827;\n      letter-spacing: -0.03em;\n    }\n\n    .ols-h5p-card h2,\n    .ols-related-card h2,\n    .ols-faq-card h2,\n    .ols-quicksnap-card h2 {\n      margin-bottom: 14px;\n    }\n\n    .ols-note-card p,\n    .ols-note-card li,\n    .ols-h5p-card p,\n    .ols-related-card p,\n    .ols-faq-card p,\n    .ols-quicksnap-card p {\n      font-size: clamp(15px, 1.25vw, 17px);\n      line-height: 1.65;\n      font-weight: 300;\n      color: var(--body-text);\n    }\n\n    .ols-note-card strong,\n    .ols-h5p-card strong,\n    .ols-related-card strong,\n    .ols-faq-card strong,\n    .ols-quicksnap-card strong {\n      font-weight: 700;\n      color: var(--navy);\n    }\n\n    .ols-note-card ul,\n    .ols-note-card ol {\n      margin: 0;\n      padding-left: 22px;\n    }\n\n    .ols-key-box {\n      margin-top: 20px;\n      background: var(--soft-green);\n      border: 1px solid rgba(63, 143, 70, 0.25);\n      border-radius: 20px;\n      padding: 18px 20px;\n    }\n\n    .ols-key-box p {\n      margin: 0;\n      font-weight: 400;\n      color: var(--navy);\n    }\n\n    .ols-definition-box {\n      background: linear-gradient(135deg, #ffffff, var(--soft-purple));\n      border: 2px dashed rgba(122, 62, 157, 0.35);\n      border-radius: 24px;\n      padding: 22px;\n      margin-top: 22px;\n    }\n\n    .ols-definition-box p {\n      margin: 0;\n      font-weight: 400;\n      color: var(--navy);\n    }\n\n    .ols-rule-list {\n      display: grid;\n      gap: 14px;\n      margin-top: 18px;\n    }\n\n    .ols-rule-item {\n      background: #ffffff;\n      border: 1px solid var(--border);\n      border-left: 5px solid var(--blue);\n      border-radius: 18px;\n      padding: 18px;\n      box-shadow: var(--inner-shadow);\n    }\n\n    .ols-rule-item h3 {\n      margin: 0 0 8px;\n      font-size: 20px;\n      line-height: 1.25;\n      color: var(--navy);\n    }\n\n    .ols-rule-item p {\n      margin: 0;\n      font-size: 15px;\n      line-height: 1.6;\n    }\n\n    .ols-figure-card {\n      margin: 26px 0 4px;\n      border: 1px solid var(--border);\n      border-radius: 26px;\n      overflow: hidden;\n      background: #ffffff;\n      box-shadow: var(--inner-shadow);\n    }\n\n    .ols-figure-image {\n      width: 100%;\n      min-height: 330px;\n      display: flex;\n      align-items: center;\n      justify-content: center;\n      background: #ffffff;\n      padding: 20px;\n    }\n\n    .ols-figure-image img {\n      max-width: 100%;\n      height: auto;\n      display: block;\n    }\n\n    .ols-figure-caption {\n      padding: 18px 22px 20px;\n      background: linear-gradient(135deg, #ffffff, #f8fbff);\n    }\n\n    .ols-figure-caption p {\n      margin: 0;\n      color: #5f6b85;\n      font-size: clamp(14px, 1.2vw, 16px);\n      line-height: 1.65;\n      font-weight: 300;\n      font-style: italic;\n    }\n\n    .ols-table-wrap {\n      overflow: hidden;\n      border-radius: 22px;\n      border: 1px solid var(--border);\n      background: #ffffff;\n      margin-top: 18px;\n    }\n\n    .ols-table {\n      width: 100%;\n      border-collapse: collapse;\n      table-layout: fixed;\n    }\n\n    .ols-table th {\n      background: var(--navy);\n      color: #ffffff;\n      padding: 16px;\n      text-align: left;\n      font-size: clamp(14px, 1.2vw, 17px);\n      font-weight: 600;\n      overflow-wrap: anywhere;\n    }\n\n    .ols-table td {\n      padding: 16px;\n      border-bottom: 1px solid var(--border);\n      font-size: clamp(14px, 1.15vw, 16px);\n      line-height: 1.45;\n      color: var(--body-text);\n      vertical-align: top;\n      overflow-wrap: anywhere;\n    }\n\n    .ols-table tr:last-child td {\n      border-bottom: none;\n    }\n\n    .ols-h5p-card {\n      background: linear-gradient(135deg, #ffffff 0%, #f7f0ff 100%);\n    }\n\n    .ols-h5p-grid {\n      display: grid;\n      grid-template-columns: 1fr;\n      gap: 16px;\n      margin-top: 22px;\n    }\n\n    .ols-h5p-frame {\n      padding: 18px;\n      border-radius: 24px;\n      background: #ffffff;\n      border: 1px solid var(--border);\n      box-shadow: inset 0 0 0 1px rgba(28, 36, 75, 0.03);\n    }\n\n    .ols-infographic-full {\n      width: 100%;\n      max-width: 100%;\n      margin: 6px 0 30px;\n      overflow: hidden;\n    }\n\n    .ols-infographic-title {\n      margin: 0 0 18px;\n    }\n\n    .ols-infographic-full-frame {\n      width: 100%;\n      max-width: 100%;\n      border-radius: 22px;\n      overflow: hidden;\n      box-shadow: 0 18px 42px rgba(28, 36, 75, 0.13);\n      background: #ffffff;\n      border: 1px solid var(--border);\n      padding: 0;\n    }\n\n    .ols-infographic-full-frame img {\n      width: 100%;\n      max-width: 100%;\n      height: auto;\n      display: block;\n      object-fit: contain;\n    }\n\n    .ols-quicksnap-card {\n      background: linear-gradient(135deg, #ffffff 0%, #eef4ff 100%);\n    }\n\n    .ols-quicksnap-list {\n      display: grid;\n      gap: 12px;\n      margin: 18px 0 0;\n      padding: 0;\n      list-style: none;\n    }\n\n    .ols-quicksnap-list li {\n      padding: 14px 16px;\n      border-radius: 16px;\n      background: #ffffff;\n      border: 1px solid var(--border);\n      box-shadow: var(--inner-shadow);\n      font-size: 16px;\n      line-height: 1.6;\n      color: var(--body-text);\n      overflow-wrap: anywhere;\n    }\n\n    .ols-course-cta-atomic-structure {\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      width: 100%;\n      margin: 30px 0 24px;\n      font-family: Poppins, Arial, sans-serif;\n    }\n\n    .ols-course-cta-atomic-structure,\n    .ols-course-cta-atomic-structure * {\n      box-sizing: border-box;\n    }\n\n    .ols-course-cta-atomic-structure .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-atomic-structure .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-atomic-structure .ols-course-cta-image-link {\n      display: block;\n      text-decoration: none;\n      border-radius: 24px;\n    }\n\n    .ols-course-cta-atomic-structure .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: transform 0.35s ease, box-shadow 0.35s ease;\n    }\n\n    .ols-course-cta-atomic-structure .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-atomic-structure .ols-course-cta-image-link:hover .ols-course-cta-image {\n      transform: translateY(-8px) scale(1.015);\n      box-shadow: 0 26px 60px rgba(28, 36, 75, 0.18), 0 0 0 1px rgba(37, 99, 235, 0.12);\n    }\n\n    .ols-course-cta-atomic-structure .ols-course-cta-image-link:hover .ols-course-cta-image img {\n      transform: scale(1.03);\n    }\n\n    .ols-course-cta-atomic-structure .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-atomic-structure .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-atomic-structure 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-atomic-structure .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-atomic-structure .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-atomic-structure .ols-course-cta-stats,\n    .ols-course-cta-atomic-structure .ols-course-cta-features {\n      display: grid;\n      grid-template-columns: repeat(2, minmax(0, 1fr));\n      gap: 14px;\n      margin: 0;\n    }\n\n    .ols-course-cta-atomic-structure .ols-course-cta-features {\n      margin-bottom: 30px;\n    }\n\n    .ols-course-cta-atomic-structure .ols-course-stat,\n    .ols-course-cta-atomic-structure .ols-course-feature {\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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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: transform 0.2s ease, background 0.2s ease, box-shadow 0.2s ease;\n    }\n\n    .ols-course-cta-atomic-structure .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-atomic-structure .ols-course-button-top {\n      flex-shrink: 0;\n      padding: 12px 22px;\n      font-size: 15px;\n    }\n\n    .ols-faq-list {\n      display: grid;\n      gap: 14px;\n      margin-top: 18px;\n    }\n\n    .ols-faq-item {\n      background: #ffffff;\n      border: 1px solid var(--border);\n      border-radius: 18px;\n      padding: 18px 20px;\n      box-shadow: var(--inner-shadow);\n    }\n\n    .ols-faq-item h3 {\n      margin: 0 0 8px;\n      font-size: 20px;\n      line-height: 1.3;\n      color: var(--navy);\n    }\n\n    .ols-faq-item p {\n      margin: 0;\n      font-size: 16px;\n      line-height: 1.65;\n      color: var(--body-text);\n    }\n\n    .ols-related-grid {\n      display: grid;\n      grid-template-columns: repeat(3, minmax(0, 1fr));\n      gap: 16px;\n      margin-top: 18px;\n    }\n\n    .ols-related-item {\n      border: 1px solid var(--border);\n      border-radius: 18px;\n      padding: 18px;\n      background: #ffffff;\n      color: var(--navy);\n      text-decoration: none;\n      font-weight: 600;\n      line-height: 1.5;\n      transition: transform 0.2s ease, box-shadow 0.2s ease;\n    }\n\n    .ols-related-item:hover {\n      transform: translateY(-2px);\n      box-shadow: 0 10px 22px rgba(28, 36, 75, 0.08);\n      color: var(--blue);\n    }\n\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: 1050px) {\n      .ols-revision-layout {\n\n      .ols-main {\n        max-width: none;\n      }\n\n      .ols-related-grid {\n        grid-template-columns: repeat(2, minmax(0, 1fr));\n      }\n\n      .ols-course-cta-atomic-structure .ols-course-cta-top,\n      .ols-course-cta-atomic-structure .ols-course-cta-intro-stats {\n        grid-template-columns: 1fr;\n      }\n\n      .ols-course-cta-atomic-structure .ols-course-cta-image-link {\n        max-width: 520px;\n        margin: 0 auto;\n      }\n    }\n\n    @media (max-width: 760px) {\n      .ols-revision-layout {\n        padding: 14px 12px 44px;\n      }\n\n      .ols-title-card,\n      .ols-note-card,\n      .ols-h5p-card,\n      .ols-related-card,\n      .ols-faq-card,\n      .ols-quicksnap-card,\n      .ols-attribution-card {\n        padding: 24px 18px;\n        border-radius: 22px;\n      }\n\n      .ols-note-title {\n\n      .ols-figure-card {\n        border-radius: 22px;\n      }\n\n      .ols-figure-image {\n        min-height: 230px;\n        padding: 14px;\n      }\n\n      .ols-figure-caption {\n        padding: 18px;\n      }\n\n      .ols-table-wrap {\n        border: none;\n        background: transparent;\n      }\n\n      .ols-table,\n      .ols-table thead,\n      .ols-table tbody,\n      .ols-table th,\n      .ols-table td,\n      .ols-table tr {\n        display: block;\n        width: 100%;\n      }\n\n      .ols-table {\n        border-collapse: separate;\n        border-spacing: 0;\n      }\n\n      .ols-table thead {\n        display: none;\n      }\n\n      .ols-table tr {\n        margin-bottom: 14px;\n        border: 1px solid var(--border);\n        border-radius: 18px;\n        overflow: hidden;\n        background: #ffffff;\n        box-shadow: var(--inner-shadow);\n      }\n\n      .ols-table td {\n        border-bottom: 1px solid var(--border);\n        padding: 14px 16px;\n        overflow-wrap: anywhere;\n      }\n\n      .ols-table td:last-child {\n        border-bottom: none;\n      }\n\n      .ols-table td::before {\n        content: attr(data-label);\n        display: block;\n        margin-bottom: 6px;\n        font-size: 13px;\n        font-weight: 700;\n        color: var(--blue);\n      }\n\n      .ols-author {\n        align-items: flex-start;\n        padding: 22px 18px;\n        border-radius: 22px;\n      }\n\n      .ols-author-avatar-img {\n        width: 72px;\n        height: 72px;\n      }\n\n      .ols-author-title {\n        font-size: 24px;\n      }\n\n      .ols-author-description {\n        font-size: 15px;\n      }\n\n      .ols-course-cta-atomic-structure .ols-course-cta-card {\n        padding: 20px;\n        border-radius: 24px;\n      }\n\n      .ols-course-cta-atomic-structure .ols-course-button,\n      .ols-course-cta-atomic-structure .ols-course-button-top {\n        width: 100%;\n      }\n    }\n\n    .ols-zoom-card, .ols-zoom-card * { box-sizing: border-box; }\n    .ols-zoom-card { display: block !important; margin: 26px 0 34px !important; border: 1px solid rgba(28, 36, 75, 0.14) !important; border-radius: 26px !important; background: #ffffff !important; box-shadow: 0 18px 45px rgba(28, 36, 75, 0.10) !important; overflow: visible !important; position: relative !important; z-index: 1 !important; isolation: isolate !important; }\n    .ols-zoom-card:hover { z-index: 50 !important; }\n    .ols-zoom-card-image { display: flex !important; align-items: center !important; justify-content: center !important; width: 100% !important; min-height: 330px !important; padding: 20px !important; background: #ffffff !important; overflow: visible !important; border-top-left-radius: 26px !important; border-top-right-radius: 26px !important; position: relative !important; z-index: 2 !important; }\n    .ols-zoom-card img.ols-zoomable-img { display: block !important; width: 100% !important; max-width: 100% !important; height: auto !important; border-radius: 18px !important; cursor: default !important; pointer-events: auto !important; user-select: none !important; -webkit-user-drag: none !important; transform: translateZ(0) scale(1) !important; transform-origin: center center !important; transition: transform 0.32s ease, box-shadow 0.32s ease, filter 0.32s ease !important; position: relative !important; z-index: 2 !important; }\n    @media (hover: hover) and (pointer: fine) { .ols-zoom-card img.ols-zoomable-img:hover { transform: translateZ(0) scale(1.45) !important; box-shadow: 0 28px 70px rgba(28, 36, 75, 0.34) !important; filter: saturate(1.02) contrast(1.01) !important; z-index: 100 !important; } }\n    .ols-zoom-card-caption { padding: 18px 22px 20px !important; background: linear-gradient(135deg, #ffffff, #f8fbff) !important; border-bottom-left-radius: 26px !important; border-bottom-right-radius: 26px !important; position: relative !important; z-index: 1 !important; }\n    .ols-zoom-card-caption p { margin: 0 !important; color: #5f6b85 !important; font-size: 15px !important; line-height: 1.65 !important; font-weight: 300 !important; font-style: italic !important; font-family: Poppins, Arial, sans-serif !important; }\n    .ols-zoom-card img.ols-lightbox-target { cursor: zoom-in !important; }\n    @media (max-width: 760px) { .ols-zoom-card { border-radius: 22px !important; overflow: hidden !important; } .ols-zoom-card-image { min-height: auto !important; padding: 12px !important; overflow: hidden !important; } .ols-zoom-card img.ols-zoomable-img, .ols-zoom-card img.ols-zoomable-img:hover { transform: none !important; box-shadow: none !important; } }\n    .ols-image-lightbox { position: fixed; inset: 0; z-index: 999999; display: none; align-items: center; justify-content: center; padding: 34px; background: rgba(10, 15, 35, 0.86); backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px); }\n    .ols-image-lightbox.is-open { display: flex; }\n    .ols-image-lightbox-inner { position: relative; width: min(96vw, 1500px); max-height: 92vh; display: flex; align-items: center; justify-content: center; }\n    .ols-image-lightbox-img { display: block; max-width: 100%; max-height: 92vh; height: auto; width: auto; border-radius: 22px; background: #ffffff; box-shadow: 0 32px 90px rgba(0,0,0,0.45); object-fit: contain; }\n    .ols-image-lightbox-close { position: absolute; top: -18px; right: -18px; width: 46px; height: 46px; border: 0; border-radius: 50%; background: #ffffff; color: #1C244B; font-family: Poppins, Arial, sans-serif; font-size: 28px; line-height: 1; font-weight: 700; cursor: pointer; box-shadow: 0 16px 34px rgba(0,0,0,0.28); display: flex; align-items: center; justify-content: center; transition: transform 0.2s ease, background 0.2s ease, color 0.2s ease; }\n    .ols-image-lightbox-close:hover { transform: scale(1.08); background: #2563eb; color: #ffffff; }\n    @media (max-width: 760px) { .ols-image-lightbox { padding: 16px; } .ols-image-lightbox-inner { width: 100%; max-height: 88vh; } .ols-image-lightbox-img { max-height: 88vh; border-radius: 16px; } .ols-image-lightbox-close { top: 10px; right: 10px; width: 42px; height: 42px; font-size: 26px; } }\n  <\/style>\n\n  <div class=\"ols-revision-layout\">\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 1 Atomic Structure and The Periodic Table<\/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\/topic-1-atomic-structure-and-the-periodic-table\/atomic-structure\/\">Atomic Structure<\/a>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/\">Mass Spectrometry<\/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\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/the-mass-spectrometer\/\">The Mass Spectrometer<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/ram-calculations\/\">RAM Calculations<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/predicting-diatomic-mass-spectra\/\">Predicting Diatomic Mass Spectra<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/identifying-compounds-from-mass-spectra\/\">Identifying Compounds from Mass Spectra<\/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\/topic-1-atomic-structure-and-the-periodic-table\/electron-configuration\/\">Electron Configuration<\/a>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/\">Ionisation Energy<\/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\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/introduction-to-ionisation-energy\/\">Introduction to Ionisation Energy<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/successive-ionisation-energies\/\">Successive Ionisation Energies<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-period\/\">Trends in a Period<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/\">Trends in a Group<\/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\/topic-1-atomic-structure-and-the-periodic-table\/periodic-trends\/\">Periodic Trends<\/a>\r\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\/topic-2-bonding-and-structure\/\">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\/topic-3-redox-i\/\">Redox I<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-4-inorganic-chemistry-and-the-periodic-table\/\">Inorganic Chemistry &amp; The Periodic Table<\/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>\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\/\">Edexcel<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/\">Topic 1 Atomic Structure &amp; The Periodic Table<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/\">Ionisation Energy<\/a> \/\n        <span>Trends in a Group<\/span>\n      <\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Trends in a Group<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to first ionisation energy trends down a group, including atomic radius, shielding, nuclear charge and why outer electrons become easier to remove.<\/p>\n\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Unit: Paper 1<\/div>\n          <div class=\"ols-badge\">Topic 1: Atomic Structure &amp; The Periodic Table<\/div>\n          <div class=\"ols-badge\">9CH0\/01<\/div>\n        <\/div>\n\n        <div class=\"ols-author\">\n          <img decoding=\"async\" class=\"ols-author-avatar-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Author-Profile.jpeg\" alt=\"Dr. Mohammed Al-Fatah\">\n          <div class=\"ols-author-content\">\n            <h2 class=\"ols-author-title\">Written by:<br><span>Dr. Mohammed Al-Fatah<\/span><\/h2>\n            <p class=\"ols-author-description\">Chemistry specialist revision notes for A Level Chemistry.<\/p>\n            <a class=\"ols-linkedin-pill\" href=\"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\" target=\"_blank\" rel=\"noopener noreferrer\">\n              <svg class=\"ols-linkedin-icon\" viewBox=\"0 0 24 24\" fill=\"currentColor\" aria-hidden=\"true\"><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\"><\/path><\/svg>\n              View LinkedIn Profile\n            <\/a>\n          <\/div>\n        <\/div>\n      <\/header>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">1<\/div><h2>What Does Going Down a Group Mean?<\/h2><\/div>\n        <p>A <strong>group<\/strong> is a vertical column in the periodic table. Elements in the same group have the same number of outer-shell electrons, so they often show similar chemical behaviour.<\/p>\n        <p>When you go down a group, each element has one more occupied electron shell than the element above it. This increases the distance between the nucleus and the outer electron.<\/p>\n        <div class=\"ols-key-box\">\n          <p><strong>Core idea:<\/strong> down a group, the outer electron is further from the nucleus and is shielded by more inner electron shells.<\/p>\n        <\/div>\n      <\/article>\n\n      <div class=\"ols-zoom-card\">\n        <div class=\"ols-zoom-card-image\">\n          <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Classification-of-elements-in-blocks.webp\" alt=\"Periodic table classification showing s, p, d and f blocks\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>Groups are vertical columns in the periodic table. The block also helps identify which subshell receives the outer electrons.<\/p>\n        <\/div>\n      <\/div>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">2<\/div><h2>Atomic Radius Increases Down a Group<\/h2><\/div>\n        <p><strong>Atomic radius increases down a group<\/strong> because each element has an additional main electron shell.<\/p>\n        <p>The outer electron is further from the nucleus, so the attraction between the nucleus and the outer electron becomes weaker. This increased distance is one of the main reasons ionisation energy decreases down a group.<\/p>\n      <\/article>\n\n      <div class=\"ols-zoom-card\">\n        <div class=\"ols-zoom-card-image\">\n          <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Atomic-radius-increase-in-Group-2.webp\" alt=\"Atomic radius increasing down Group 2\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>Each element lower in Group 2 has an extra occupied electron shell, so its outer electron is further from the nucleus.<\/p>\n        <\/div>\n      <\/div>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">3<\/div><h2>Shielding Increases Down a Group<\/h2><\/div>\n        <p>As atoms get larger down a group, there are more inner shells between the nucleus and the outer electron. These inner shells <strong>shield<\/strong> the outer electron from the full attraction of the nucleus.<\/p>\n        <p>This means the outer electron experiences a lower effective nuclear attraction, even though the total number of protons in the nucleus has increased.<\/p>\n        <div class=\"ols-definition-box\">\n          <p><strong>Shielding:<\/strong> the reduction in attraction between the nucleus and an outer electron due to repulsion from inner-shell electrons.<\/p>\n        <\/div>\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Factor down a group<\/th>\n                <th>What happens?<\/th>\n                <th>Effect on the outer electron<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Factor down a group\">Number of shells<\/td>\n                <td data-label=\"What happens?\">Increases<\/td>\n                <td data-label=\"Effect on the outer electron\">Outer electron is further from the nucleus.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Factor down a group\">Shielding<\/td>\n                <td data-label=\"What happens?\">Increases<\/td>\n                <td data-label=\"Effect on the outer electron\">Inner shells reduce the attraction felt by the outer electron.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Factor down a group\">Nuclear charge<\/td>\n                <td data-label=\"What happens?\">Increases<\/td>\n                <td data-label=\"Effect on the outer electron\">More protons increase attraction, but this is outweighed by extra shells and shielding.<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Factor down a group\">First ionisation energy<\/td>\n                <td data-label=\"What happens?\">Decreases<\/td>\n                <td data-label=\"Effect on the outer electron\">Less energy is needed to remove the outer electron.<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card orange\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">4<\/div><h2>First Ionisation Energy Decreases Down a Group<\/h2><\/div>\n        <p>First ionisation energy generally <strong>decreases down a group<\/strong>. This means it becomes easier to remove the outer electron from atoms lower in the group.<\/p>\n        <p>The nuclear charge does increase because atoms lower in the group have more protons. However, the effect of the extra shells and increased shielding is greater. The outer electron is less strongly attracted to the nucleus, so less energy is needed to remove it.<\/p>\n        <div class=\"ols-key-box\">\n          <p><strong>Best exam answer:<\/strong> down a group, there are more occupied shells, the outer electron is further from the nucleus and shielding increases. These effects outweigh the increased nuclear charge.<\/p>\n        <\/div>\n      <\/article>\n\n\n      <section class=\"ols-h5p-card\">\n        <h2>Check Your Understanding<\/h2>\n        <p>Use these short tasks to test the key reasons why first ionisation energy decreases down a group.<\/p>\n        <div class=\"ols-h5p-grid\">\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-275\" class=\"h5p-iframe\" data-content-id=\"275\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T2.4.13 Drag: Trends in a Group Key Concepts\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-279\" class=\"h5p-iframe\" data-content-id=\"279\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T2.4.14 MCQ: First Ionisation Energy Down a Group\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-280\" class=\"h5p-iframe\" data-content-id=\"280\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T2.4.15 MCQ: Shielding Down a Group\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-281\" class=\"h5p-iframe\" data-content-id=\"281\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T2.4.16 MCQ: Nuclear Charge Down a Group\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-351\" class=\"h5p-iframe\" data-content-id=\"351\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Ionisation Energy: Trends in a Group Dialog Cards\"><\/iframe><\/div><\/div>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-quicksnap-card\">\n        <h2>QuickSnap<\/h2>\n        <p>This text summary condenses the page into the essential exam ideas.<\/p>\n        <ul class=\"ols-quicksnap-list\">\n          <li><strong>Down a group, atomic radius increases<\/strong> because each element has an additional occupied electron shell.<\/li>\n          <li><strong>The outer electron is further from the nucleus<\/strong>, so the attraction between the nucleus and the outer electron is weaker.<\/li>\n          <li><strong>Shielding increases<\/strong> because there are more inner shells between the nucleus and the outer electron.<\/li>\n          <li><strong>Nuclear charge increases<\/strong>, but the effect of extra shells and shielding outweighs this.<\/li>\n          <li><strong>First ionisation energy decreases<\/strong>, so less energy is needed to remove the outer electron.<\/li>\n          <li><strong>Best exam answers<\/strong> explicitly use distance from the nucleus, shielding, nuclear charge and attraction.<\/li>\n        <\/ul>\n      <\/section>\n\n\n<section class=\"ols-course-cta-atomic-structure\" id=\"olsCourseCtaAtomicStructure002\">\n        <style>\n          .ols-course-cta-atomic-structure,\n          .ols-course-cta-atomic-structure * {\n            box-sizing: border-box;\n          }\n      \n          .ols-course-cta-atomic-structure {\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-atomic-structure .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-atomic-structure .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-atomic-structure .ols-course-cta-image-link {\n            display: block;\n            text-decoration: none;\n            border-radius: 24px;\n          }\n      \n          .ols-course-cta-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .ols-course-cta-image-link:hover .ols-course-cta-image img {\n            transform: scale(1.03);\n          }\n      \n          .ols-course-cta-atomic-structure .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-atomic-structure .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-atomic-structure 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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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\/05\/T1-Atomic-Structure-and-The-Periodic-Table.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-atomic-structure .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-atomic-structure .ols-animation-start-overlay.is-hidden {\n            opacity: 0;\n            visibility: hidden;\n            pointer-events: none;\n          }\n      \n          .ols-course-cta-atomic-structure .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-atomic-structure .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: olsAnimationPlayPulse002 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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .ols-animation-pause-button.is-visible {\n            display: inline-flex;\n          }\n      \n          @keyframes olsAnimationPlayPulse002 {\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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .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-atomic-structure .ols-course-cta-top {\n              grid-template-columns: 1fr;\n            }\n      \n            .ols-course-cta-atomic-structure .ols-course-cta-image-link {\n              max-width: 520px;\n              margin: 0 auto;\n            }\n      \n            .ols-course-cta-atomic-structure .ols-course-cta-intro-stats {\n              grid-template-columns: 1fr;\n            }\n      \n            .ols-course-cta-atomic-structure .ols-animation-frame-shell {\n              height: 520px;\n            }\n          }\n      \n          @media (max-width: 760px) {\n            .ols-course-cta-atomic-structure {\n              margin: 26px 0 22px;\n            }\n      \n            .ols-course-cta-atomic-structure .ols-course-cta-card {\n              padding: 20px;\n              border-radius: 24px;\n            }\n      \n            .ols-course-cta-atomic-structure .ols-course-cta-header-row {\n              align-items: stretch;\n            }\n      \n            .ols-course-cta-atomic-structure .ols-course-button-top {\n              width: 100%;\n            }\n      \n            .ols-course-cta-atomic-structure .ols-course-cta-stats,\n            .ols-course-cta-atomic-structure .ols-course-cta-features {\n              grid-template-columns: 1fr;\n            }\n      \n            .ols-course-cta-atomic-structure .ols-course-animation-wrap {\n              padding: 0;\n              border-radius: 0;\n            }\n      \n            .ols-course-cta-atomic-structure .ols-animation-frame-shell {\n              height: 420px;\n              border-radius: 18px;\n            }\n      \n            .ols-course-cta-atomic-structure .ols-animation-play-circle {\n              width: 76px;\n              height: 76px;\n            }\n      \n            .ols-course-cta-atomic-structure .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-atomic-structure .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-atomic-structure .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\/atomic-structure-and-the-periodic-table-topic-1\/\" aria-label=\"Open the Edexcel A Level Chemistry Topic 1 Atomic Structure and The Periodic Table course page\">\n      \n              <div class=\"ols-course-cta-image\">\n                <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/T1-Atomic-Structure-and-The-Periodic-Table.jpg\" alt=\"Edexcel A Level Chemistry Topic 1 Atomic Structure and The Periodic Table course banner\">\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 1 Atomic Structure &amp; The Periodic Table Course\n                <\/div>\n      \n                <a class=\"ols-course-button ols-course-button-top\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/atomic-structure-and-the-periodic-table-topic-1\/\">\n                  View Course\n                <\/a>\n      \n              <\/div>\n      \n              <h2>\n                Master Atomic Structure and The Periodic Table for Edexcel 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 1 Atomic Structure and The Periodic Table 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>18 hours<\/strong>\n              <\/div>\n      \n              <div class=\"ols-course-stat\">\n                <span>Video lessons<\/span>\n                <strong>369 mins<\/strong>\n              <\/div>\n      \n              <div class=\"ols-course-stat\">\n                <span>MCQ practice<\/span>\n                <strong>86 marks<\/strong>\n              <\/div>\n      \n              <div class=\"ols-course-stat\">\n                <span>SAQ practice<\/span>\n                <strong>215 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 atomic structure, isotopes, mass spectrometry, ionisation energy, electron configuration and periodic trends 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 atomic structure, isotopes, mass spectrometry, ionisation energies, electron configuration and periodic trends 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 id=\"olsCourseAnimationFrame002\" title=\"OLS course preview animation\" loading=\"lazy\" referrerpolicy=\"no-referrer\">\n              <\/iframe>\n      \n              <button class=\"ols-animation-start-overlay\" id=\"olsCourseAnimationStart002\" type=\"button\" 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 class=\"ols-animation-pause-button\" id=\"olsCourseAnimationPause002\" type=\"button\" 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\/atomic-structure-and-the-periodic-table-topic-1\/\">\n              View Atomic Structure &amp; The Periodic Table Topic 1 Course\n            <\/a>\n      \n          <\/div>\n      \n        <\/div>\n      \n        <template id=\"olsCourseAnimationTemplate002\">\n\n\n\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*{\n  box-sizing:border-box;\n}\n\n:root{\n  --ols-video-screen-w:1180;\n  --ols-video-screen-h:664;\n  --ols-video-screen-scale:1;\n\n  --ols-mcq-screen-w:1360;\n  --ols-mcq-screen-h:1130;\n  --ols-mcq-screen-scale:1;\n\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\/* ============================================================\n   GLOBAL SCENE SYSTEM\n============================================================ *\/\n\n.ols-combined-stage{\n  position:relative;\n  width:100vw;\n  height:100vh;\n  overflow:hidden;\n\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\n  width:100vw;\n  height:100vh;\n\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\n  width:5px;\n  height:0.85em;\n\n  background:#1C244B;\n\n  margin-left:8px;\n\n  transform:translateY(8px);\n\n  animation:olsBlink 0.8s infinite;\n}\n\n.cursor{\n  display:inline-block;\n\n  width:3px;\n  height:28px;\n\n  background:#1c244b;\n\n  margin-left:3px;\n\n  transform:translateY(5px);\n\n  animation:olsBlink 0.8s infinite;\n}\n\n@keyframes olsBlink{\n  0%,45%{\n    opacity:1;\n  }\n  46%,100%{\n    opacity:0;\n  }\n}\n\n.ols-combined-stage.ols-animation-paused *,\n.ols-combined-stage.ols-animation-paused *::before,\n.ols-combined-stage.ols-animation-paused *::after{\n  animation-play-state:paused !important;\n}\n\n\/* ============================================================\n   1. VIRTUAL LESSON PROMO\n============================================================ *\/\n\n.ols-video-stage{\n  width:100vw;\n  height:100vh;\n\n  display:flex;\n  justify-content:center;\n  align-items:center;\n\n  padding:0;\n  overflow:hidden;\n\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  position:absolute;\n  inset:0;\n  z-index:20;\n\n  display:flex;\n  justify-content:center;\n  align-items:center;\n\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  opacity:1;\n  visibility:visible;\n  pointer-events:none;\n}\n\n.ols-video-title-screen.hide{\n  animation:olsVideoTitleFadeOut 0.85s ease forwards;\n}\n\n@keyframes olsVideoTitleFadeOut{\n  to{\n    opacity:0;\n    visibility:hidden;\n  }\n}\n\n.ols-video-title-wrap{\n  max-width:1250px;\n  padding:0 34px;\n  text-align:center;\n}\n\n.ols-video-title{\n  margin:0;\n\n  font-family:Poppins,Arial,sans-serif;\n\n  font-size:clamp(52px,8vw,124px);\n  font-weight:600;\n  line-height:1.08;\n\n  color:#1C244B;\n\n  text-shadow:-9px 0 9px rgba(28,36,75,0.16);\n\n  letter-spacing:-0.045em;\n}\n\n#videoTitleText{\n  white-space:pre-wrap;\n}\n\n.ols-video-scene{\n  width:100%;\n  height:100%;\n\n  display:flex;\n  justify-content:center;\n  align-items:center;\n\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{\n  to{\n    opacity:1;\n  }\n}\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\n  transform:scale(var(--ols-video-screen-scale));\n  transform-origin:center center;\n\n  display:flex;\n  justify-content:center;\n  align-items:center;\n}\n\n.ols-video-card{\n  width:1180px;\n  height:664px;\n\n  border-radius:28px;\n  overflow:hidden;\n\n  background:#1C244B;\n\n  box-shadow:\n    0 28px 80px rgba(28,36,75,0.28);\n\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\n  aspect-ratio:16 \/ 9;\n  object-fit:cover;\n\n  border:0;\n}\n\n\/* ============================================================\n   2. MULTIPLE CHOICE FEEDBACK\n============================================================ *\/\n\n.ols-mcq-stage{\n  width:100vw;\n  height:100vh;\n\n  display:flex;\n  justify-content:center;\n  align-items:center;\n\n  padding:0;\n  overflow:hidden;\n\n  background:\n    radial-gradient(circle at top left,rgba(70,127,247,0.16),transparent 34%),\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\n}\n\n.ols-mcq-intro-screen{\n  position:absolute;\n  inset:0;\n  z-index:50;\n\n  display:flex;\n  justify-content:center;\n  align-items:center;\n\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  opacity:1;\n  visibility:visible;\n  pointer-events:none;\n}\n\n.ols-mcq-intro-screen.hide{\n  animation:olsMcqIntroFadeOut 0.85s ease forwards;\n}\n\n@keyframes olsMcqIntroFadeOut{\n  to{\n    opacity:0;\n    visibility:hidden;\n  }\n}\n\n.ols-mcq-intro-title-wrap{\n  max-width:1250px;\n  padding:0 34px;\n  text-align:center;\n}\n\n.ols-mcq-intro-title{\n  margin:0;\n\n  font-family:Poppins,Arial,sans-serif;\n\n  font-size:clamp(52px,8vw,124px);\n  font-weight:600;\n  line-height:1.08;\n\n  color:#1C244B;\n\n  text-shadow:-9px 0 9px rgba(28,36,75,0.16);\n\n  letter-spacing:-0.045em;\n}\n\n#mcqIntroTitleText{\n  white-space:pre-wrap;\n}\n\n.ols-mcq-scale-wrap{\n  width:calc(var(--ols-mcq-screen-w) * 1px);\n  height:calc(var(--ols-mcq-screen-h) * 1px);\n\n  transform:scale(var(--ols-mcq-screen-scale));\n  transform-origin:center center;\n\n  display:flex;\n  justify-content:center;\n  align-items:flex-start;\n}\n\n.ols-mcq-screen{\n  width:1360px;\n  height:1130px;\n\n  border-radius:22px;\n  overflow:hidden;\n\n  background:#eaf0ff;\n\n  box-shadow:\n    0 26px 70px rgba(28,36,75,0.22);\n\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{\n    opacity:0;\n    transform:translateY(24px) scale(0.96);\n  }\n  to{\n    opacity:1;\n    transform:translateY(0) scale(1);\n  }\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:\n    opacity 0.25s ease,\n    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-option-row.selected .mcq-radio{\n  border-color:#4b5563;\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%{\n    opacity:0.65;\n    transform:translate(-50%,-50%) scale(1);\n  }\n  100%{\n    opacity:0;\n    transform:translate(-50%,-50%) scale(2.5);\n  }\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:\n    opacity 0.35s ease,\n    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\n  display:inline-flex;\n  justify-content:center;\n  align-items:center;\n\n  font-size:18px;\n  font-weight:700;\n\n  margin-right:12px;\n\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%{\n    opacity:1;\n    transform:scale(1.18);\n  }\n  100%{\n    opacity:1;\n    transform:scale(1);\n  }\n}\n\n.mcq-specific-feedback-text{\n  display:inline-block;\n\n  background:#fff4b8;\n  color:#111827;\n\n  padding:8px 16px;\n\n  font-size:22px;\n  line-height:1.35;\n\n  min-width:850px;\n  min-height:44px;\n}\n\n.mcq-submit-button{\n  position:absolute;\n  right:34px;\n  bottom:30px;\n\n  border:0;\n  border-radius:999px;\n\n  background:#1C244B;\n  color:#ffffff;\n\n  padding:14px 28px;\n\n  font-size:18px;\n  font-weight:600;\n\n  box-shadow:\n    0 14px 32px rgba(28,36,75,0.25);\n\n  cursor:default;\n\n  transform:translateY(0) scale(1);\n\n  transition:\n    transform 0.2s ease,\n    box-shadow 0.2s ease,\n    background 0.2s ease;\n}\n\n.mcq-submit-button.clicked{\n  transform:translateY(2px) scale(0.97);\n  background:#26315f;\n  box-shadow:\n    0 7px 18px rgba(28,36,75,0.22);\n}\n\n.mcq-general-feedback{\n  height:520px;\n\n  background:#fff3c9;\n  color:#8a6a00;\n\n  padding:26px 30px 28px;\n\n  font-size:23px;\n  line-height:1.34;\n\n  opacity:0;\n  transform:translateY(20px);\n\n  transition:\n    opacity 0.7s ease,\n    transform 0.7s ease;\n\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{\n  background:#111827;\n}\n\n.mcq-general-cursor{\n  background:#8a6a00;\n}\n\n\/* ============================================================\n   3. SHORT ANSWER FEEDBACK\n============================================================ *\/\n\n.ols-saq-stage{\n  width:100vw;\n  height:100vh;\n\n  display:flex;\n  justify-content:center;\n  align-items:center;\n\n  padding:0;\n  overflow:hidden;\n\n  background:\n    radial-gradient(circle at top left,rgba(70,127,247,0.16),transparent 34%),\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\n}\n\n.ols-saq-intro{\n  position:absolute;\n  inset:0;\n  z-index:50;\n\n  display:flex;\n  justify-content:center;\n  align-items:center;\n\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  opacity:1;\n  visibility:visible;\n  pointer-events:none;\n}\n\n.ols-saq-intro.hide{\n  animation:olsSaqIntroFadeOut 0.85s ease forwards;\n}\n\n@keyframes olsSaqIntroFadeOut{\n  to{\n    opacity:0;\n    visibility:hidden;\n  }\n}\n\n.ols-saq-intro-title-wrap{\n  max-width:1250px;\n  padding:0 34px;\n  text-align:center;\n}\n\n.ols-saq-intro-title{\n  margin:0;\n\n  font-family:Poppins,Arial,sans-serif;\n\n  font-size:clamp(52px,8vw,124px);\n  font-weight:600;\n  line-height:1.08;\n\n  color:#1C244B;\n\n  text-shadow:-9px 0 9px rgba(28,36,75,0.16);\n\n  letter-spacing:-0.045em;\n}\n\n#saqIntroTitleText{\n  white-space:pre-wrap;\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\n  transform:scale(var(--ols-saq-screen-scale));\n  transform-origin:center center;\n\n  display:flex;\n  justify-content:center;\n  align-items:flex-start;\n}\n\n.ols-saq-screen{\n  width:1360px;\n  height:965px;\n\n  border-radius:22px;\n  overflow:hidden;\n\n  background:#eaf0ff;\n\n  box-shadow:\n    0 26px 70px rgba(28,36,75,0.22);\n\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{\n    opacity:0;\n    transform:translateY(24px) scale(0.96);\n  }\n  to{\n    opacity:1;\n    transform:translateY(0) scale(1);\n  }\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\n  background:#f3f4f6;\n\n  border:2px solid #cfd6e3;\n  border-radius:8px;\n\n  padding:23px 26px;\n\n  font-size:24px;\n  line-height:1.55;\n\n  color:#4b5563;\n\n  position:relative;\n  overflow:hidden;\n}\n\n.saq-teacher-feedback{\n  height:630px;\n\n  background:#dff3e6;\n  color:#075f3b;\n\n  padding:28px 40px 30px;\n\n  font-size:23px;\n  line-height:1.47;\n\n  opacity:0;\n  transform:translateY(20px);\n\n  transition:\n    opacity 0.7s ease,\n    transform 0.7s ease;\n\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\/* ============================================================\n   SMALL WINDOW PROTECTION\n============================================================ *\/\n\n@media(max-width:900px){\n\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}\n<\/style>\n\n\n\n\n<div class=\"ols-combined-stage\">\n\n  <!-- ========================================================\n       SCENE 1: VIRTUAL LESSON\n  ========================================================= -->\n\n  <section id=\"sceneVideo\" class=\"ols-scene active\">\n\n    <div class=\"ols-video-stage\">\n\n      <div id=\"videoTitleScreen\" class=\"ols-video-title-screen\">\n\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\n      <\/div>\n\n      <section id=\"videoScene\" class=\"ols-video-scene\">\n\n        <div class=\"ols-video-scale-wrap\">\n\n          <div class=\"ols-video-card\">\n            <video id=\"lessonVideo\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Virtual-Lesson.mp4\" muted=\"\" playsinline=\"\" preload=\"auto\">\n            <\/video>\n          <\/div>\n\n        <\/div>\n\n      <\/section>\n\n    <\/div>\n\n  <\/section>\n\n  <!-- ========================================================\n       SCENE 2: MULTIPLE CHOICE FEEDBACK\n  ========================================================= -->\n\n  <section id=\"sceneMcq\" class=\"ols-scene\">\n\n    <div class=\"ols-mcq-stage\">\n\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\n        <main id=\"mcqScreen\" class=\"ols-mcq-screen\">\n\n          <section class=\"mcq-question-area\">\n\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\n              <tbody>\n                <tr>\n                  <td>Na<sup>+<\/sup><\/td>\n                  <td>0.102<\/td>\n                <\/tr>\n\n                <tr>\n                  <td>K<sup>+<\/sup><\/td>\n                  <td>0.138<\/td>\n                <\/tr>\n\n                <tr>\n                  <td>F<sup>\u2212<\/sup><\/td>\n                  <td>0.133<\/td>\n                <\/tr>\n\n                <tr>\n                  <td>Cl<sup>\u2212<\/sup><\/td>\n                  <td>0.180<\/td>\n                <\/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\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\">\n                <span class=\"mcq-radio\"><\/span>\n                <span class=\"mcq-radio-ripple\"><\/span>\n                <span class=\"mcq-option-label\">potassium chloride<\/span>\n              <\/div>\n\n              <div class=\"mcq-option-row\">\n                <span class=\"mcq-radio\"><\/span>\n                <span class=\"mcq-radio-ripple\"><\/span>\n                <span class=\"mcq-option-label\">sodium fluoride<\/span>\n              <\/div>\n\n              <div class=\"mcq-option-row\">\n                <span class=\"mcq-radio\"><\/span>\n                <span class=\"mcq-radio-ripple\"><\/span>\n                <span class=\"mcq-option-label\">potassium fluoride<\/span>\n              <\/div>\n\n            <\/div>\n\n            <button id=\"mcqSubmitButton\" class=\"mcq-submit-button\">Submit answer<\/button>\n\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\n        <\/main>\n\n      <\/div>\n\n    <\/div>\n\n  <\/section>\n\n  <!-- ========================================================\n       SCENE 3: SHORT ANSWER FEEDBACK\n  ========================================================= -->\n\n  <section id=\"sceneSaq\" class=\"ols-scene\">\n\n    <div class=\"ols-saq-stage\">\n\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\n        <main id=\"saqScreen\" class=\"ols-saq-screen\">\n\n          <section class=\"saq-question-area\">\n\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\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\n        <\/main>\n\n      <\/div>\n\n    <\/div>\n\n  <\/section>\n\n<\/div>\n\n<script>\n\/* ============================================================\n   70% VIEWPORT PLAY \/ PAUSE CONTROLLER\n============================================================ *\/\n\nconst olsStage =\ndocument.querySelector(\".ols-combined-stage\");\n\nlet olsAnimationHasStarted = false;\nlet olsAnimationIsVisibleEnough = false;\nlet olsAnimationPaused = true;\n\nconst olsNativeSetTimeout = window.setTimeout.bind(window);\nconst olsNativeClearTimeout = window.clearTimeout.bind(window);\nconst olsPausableTimers = new Map();\nlet olsPausableTimerId = 1;\n\nwindow.setTimeout = function(callback,delay,...args){\n\n  const timerId = olsPausableTimerId++;\n\n  const timer = {\n    callback,\n    delay:Number(delay) || 0,\n    remaining:Number(delay) || 0,\n    args,\n    startedAt:Date.now(),\n    nativeId:null,\n    completed:false\n  };\n\n  function runTimer(){\n\n    if(timer.completed){\n      return;\n    }\n\n    timer.completed = true;\n    olsPausableTimers.delete(timerId);\n    callback(...args);\n\n  }\n\n  timer.runTimer = runTimer;\n\n  olsPausableTimers.set(timerId,timer);\n\n  if(!olsAnimationPaused && olsAnimationIsVisibleEnough){\n    timer.startedAt = Date.now();\n    timer.nativeId = olsNativeSetTimeout(runTimer,timer.remaining);\n  }\n\n  return timerId;\n\n};\n\nwindow.clearTimeout = function(timerId){\n\n  const timer = olsPausableTimers.get(timerId);\n\n  if(timer){\n\n    timer.completed = true;\n\n    if(timer.nativeId !== null){\n      olsNativeClearTimeout(timer.nativeId);\n    }\n\n    olsPausableTimers.delete(timerId);\n\n  }\n\n};\n\nfunction olsPauseTimers(){\n\n  olsPausableTimers.forEach((timer) => {\n\n    if(timer.completed){\n      return;\n    }\n\n    if(timer.nativeId !== null){\n\n      const elapsed = Date.now() - timer.startedAt;\n      timer.remaining = Math.max(0,timer.remaining - elapsed);\n\n      olsNativeClearTimeout(timer.nativeId);\n      timer.nativeId = null;\n\n    }\n\n  });\n\n}\n\nfunction olsResumeTimers(){\n\n  olsPausableTimers.forEach((timer) => {\n\n    if(timer.completed || timer.nativeId !== null){\n      return;\n    }\n\n    timer.startedAt = Date.now();\n    timer.nativeId = olsNativeSetTimeout(timer.runTimer,timer.remaining);\n\n  });\n\n}\n\nfunction olsPauseAnimation(){\n\n  if(olsAnimationPaused){\n    return;\n  }\n\n  olsAnimationPaused = true;\n\n  if(olsStage){\n    olsStage.classList.add(\"ols-animation-paused\");\n  }\n\n  if(typeof lessonVideo !== \"undefined\" && lessonVideo){\n    lessonVideo.pause();\n  }\n\n  olsPauseTimers();\n\n}\n\nfunction olsResumeAnimation(){\n\n  if(!olsAnimationPaused){\n    return;\n  }\n\n  olsAnimationPaused = false;\n\n  if(olsStage){\n    olsStage.classList.remove(\"ols-animation-paused\");\n  }\n\n  olsResumeTimers();\n\n  if(\n    typeof lessonVideo !== \"undefined\" &&\n    lessonVideo &&\n    videoScene &&\n    videoScene.classList.contains(\"show\") &&\n    !videoSceneComplete &&\n    !lessonVideo.ended\n  ){\n\n    lessonVideo.muted = true;\n\n    const resumePromise = lessonVideo.play();\n\n    if(resumePromise !== undefined){\n      resumePromise.catch(() => {});\n    }\n\n  }\n\n}\n\nfunction olsGetVisibleRatio(element){\n\n  if(!element){\n    return 0;\n  }\n\n  const rect = element.getBoundingClientRect();\n  const viewportHeight = window.innerHeight || document.documentElement.clientHeight;\n  const viewportWidth = window.innerWidth || document.documentElement.clientWidth;\n\n  const visibleHeight = Math.max(0,Math.min(rect.bottom,viewportHeight) - Math.max(rect.top,0));\n  const visibleWidth = Math.max(0,Math.min(rect.right,viewportWidth) - Math.max(rect.left,0));\n\n  const visibleArea = visibleHeight * visibleWidth;\n  const totalArea = Math.max(1,rect.width * rect.height);\n\n  return visibleArea \/ totalArea;\n\n}\n\nfunction olsHandleVisibilityRatio(ratio){\n\n  if(ratio >= 0.7){\n\n    olsAnimationIsVisibleEnough = true;\n\n    if(!olsAnimationHasStarted){\n\n      olsAnimationHasStarted = true;\n      olsAnimationPaused = false;\n\n      if(olsStage){\n        olsStage.classList.remove(\"ols-animation-paused\");\n      }\n\n      startVideoSection();\n\n    }else{\n\n      olsResumeAnimation();\n\n    }\n\n  }else{\n\n    olsAnimationIsVisibleEnough = false;\n    olsPauseAnimation();\n\n  }\n\n}\n\nfunction initialiseOlsVisibilityControlledAnimation(){\n\n  if(olsStage){\n    olsStage.classList.add(\"ols-animation-paused\");\n  }\n\n  const initialRatio = olsGetVisibleRatio(olsStage);\n  olsHandleVisibilityRatio(initialRatio);\n\n  if(\"IntersectionObserver\" in window && olsStage){\n\n    const observer = new IntersectionObserver((entries) => {\n\n      entries.forEach((entry) => {\n        olsHandleVisibilityRatio(entry.intersectionRatio);\n      });\n\n    },{\n      threshold:[0,0.25,0.5,0.69,0.7,0.85,1]\n    });\n\n    observer.observe(olsStage);\n\n  }else{\n\n    window.addEventListener(\"scroll\",() => {\n      olsHandleVisibilityRatio(olsGetVisibleRatio(olsStage));\n    },{passive:true});\n\n    window.addEventListener(\"resize\",() => {\n      olsHandleVisibilityRatio(olsGetVisibleRatio(olsStage));\n    });\n\n  }\n\n}\n\n\/* ============================================================\n   GLOBAL HELPERS\n============================================================ *\/\n\nfunction typeWriter(target,text,speed,callback){\n\n  let i = 0;\n\n  function typing(){\n\n    if(i < text.length){\n\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\n    }else{\n\n      if(callback){\n        callback();\n      }\n\n    }\n\n  }\n\n  typing();\n\n}\n\nfunction switchScene(currentScene,nextScene,callback){\n\n  currentScene.classList.add(\"fade-out\");\n\n  setTimeout(() => {\n\n    currentScene.classList.remove(\"active\");\n    currentScene.classList.remove(\"fade-out\");\n\n    nextScene.classList.add(\"active\");\n\n    if(callback){\n      callback();\n    }\n\n  },850);\n\n}\n\nfunction fitAllScreens(){\n\n  fitVideoScreen();\n  fitMcqScreen();\n  fitSaqScreen();\n\n}\n\nwindow.addEventListener(\"resize\",fitAllScreens);\nwindow.addEventListener(\"orientationchange\",fitAllScreens);\n\n\/* ============================================================\n   RESPONSIVE FITTING\n============================================================ *\/\n\nfunction fitVideoScreen(){\n\n  const baseWidth = 1180;\n  const baseHeight = 664;\n\n  const safePadding = 24;\n\n  const availableWidth = window.innerWidth - safePadding;\n  const availableHeight = window.innerHeight - safePadding;\n\n  const scaleByWidth = availableWidth \/ baseWidth;\n  const scaleByHeight = availableHeight \/ baseHeight;\n\n  const finalScale = Math.min(scaleByWidth,scaleByHeight,1);\n\n  document.documentElement.style.setProperty(\"--ols-video-screen-scale\",finalScale.toFixed(4));\n\n}\n\nfunction fitMcqScreen(){\n\n  const baseWidth = 1360;\n  const baseHeight = 1130;\n\n  const safePadding = 24;\n\n  const availableWidth = window.innerWidth - safePadding;\n  const availableHeight = window.innerHeight - safePadding;\n\n  const scaleByWidth = availableWidth \/ baseWidth;\n  const scaleByHeight = availableHeight \/ baseHeight;\n\n  const finalScale = Math.min(scaleByWidth,scaleByHeight,1);\n\n  document.documentElement.style.setProperty(\"--ols-mcq-screen-scale\",finalScale.toFixed(4));\n\n}\n\nfunction fitSaqScreen(){\n\n  const baseWidth = 1360;\n  const baseHeight = 965;\n\n  const safePadding = 24;\n\n  const availableWidth = window.innerWidth - safePadding;\n  const availableHeight = window.innerHeight - safePadding;\n\n  const scaleByWidth = availableWidth \/ baseWidth;\n  const scaleByHeight = availableHeight \/ baseHeight;\n\n  const finalScale = Math.min(scaleByWidth,scaleByHeight,1);\n\n  document.documentElement.style.setProperty(\"--ols-saq-screen-scale\",finalScale.toFixed(4));\n\n}\n\nfitAllScreens();\n\n\/* ============================================================\n   SCENE ELEMENTS\n============================================================ *\/\n\nconst sceneVideo =\ndocument.getElementById(\"sceneVideo\");\n\nconst sceneMcq =\ndocument.getElementById(\"sceneMcq\");\n\nconst sceneSaq =\ndocument.getElementById(\"sceneSaq\");\n\n\/* ============================================================\n   1. VIRTUAL LESSON PROMO\n============================================================ *\/\n\nconst videoTitle =\n\"Online Chemistry Lessons\";\n\nconst videoTitleText =\ndocument.getElementById(\"videoTitleText\");\n\nconst videoTitleCursor =\ndocument.getElementById(\"videoTitleCursor\");\n\nconst videoTitleScreen =\ndocument.getElementById(\"videoTitleScreen\");\n\nconst videoScene =\ndocument.getElementById(\"videoScene\");\n\nconst lessonVideo =\ndocument.getElementById(\"lessonVideo\");\n\nlet videoFallbackTimer = null;\nlet videoSceneComplete = false;\n\nfunction playLessonVideo(){\n\n  lessonVideo.muted = true;\n  lessonVideo.currentTime = 0;\n\n  const playPromise = lessonVideo.play();\n\n  if(playPromise !== undefined){\n\n    playPromise.catch(() => {\n\n      lessonVideo.muted = true;\n      lessonVideo.play();\n\n    });\n\n  }\n\n}\n\nfunction completeVideoScene(){\n\n  if(videoSceneComplete){\n    return;\n  }\n\n  videoSceneComplete = true;\n\n  if(videoFallbackTimer){\n    clearTimeout(videoFallbackTimer);\n  }\n\n  lessonVideo.pause();\n\n  setTimeout(() => {\n\n    switchScene(sceneVideo,sceneMcq,() => {\n      startMcqIntro();\n    });\n\n  },1400);\n\n}\n\nlessonVideo.addEventListener(\"ended\",() => {\n\n  lessonVideo.pause();\n  completeVideoScene();\n\n});\n\nfunction startVideoSection(){\n\n  fitVideoScreen();\n\n  setTimeout(() => {\n\n    typeWriter(videoTitleText,videoTitle,44,() => {\n\n      setTimeout(() => {\n\n        videoTitleCursor.style.display = \"none\";\n\n        setTimeout(() => {\n\n          videoTitleScreen.classList.add(\"hide\");\n\n          setTimeout(() => {\n\n            videoScene.classList.add(\"show\");\n\n            setTimeout(() => {\n\n              playLessonVideo();\n\n              videoFallbackTimer = setTimeout(() => {\n                completeVideoScene();\n              },45000);\n\n            },600);\n\n          },850);\n\n        },3000);\n\n      },250);\n\n    });\n\n  },700);\n\n}\n\n\/* ============================================================\n   2. MULTIPLE CHOICE FEEDBACK\n============================================================ *\/\n\nconst mcqIntroTitle =\n\"Multiple Choice Question Bank\";\n\nconst mcqSpecificFeedbackText =\n\"Na\u207a is small, but Cl\u207b is larger than F\u207b, so the ionic bonding is weaker than in NaF.\";\n\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 =\ndocument.getElementById(\"mcqIntroScreen\");\n\nconst mcqIntroTitleText =\ndocument.getElementById(\"mcqIntroTitleText\");\n\nconst mcqIntroTitleCursor =\ndocument.getElementById(\"mcqIntroTitleCursor\");\n\nconst mcqScreen =\ndocument.getElementById(\"mcqScreen\");\n\nconst mcqWrongOption =\ndocument.getElementById(\"mcqWrongOption\");\n\nconst mcqSubmitButton =\ndocument.getElementById(\"mcqSubmitButton\");\n\nconst mcqSpecificFeedback =\ndocument.getElementById(\"mcqSpecificFeedback\");\n\nconst mcqCrossIcon =\ndocument.getElementById(\"mcqCrossIcon\");\n\nconst mcqSpecificText =\ndocument.getElementById(\"mcqSpecificText\");\n\nconst mcqSpecificCursor =\ndocument.getElementById(\"mcqSpecificCursor\");\n\nconst mcqGeneralFeedback =\ndocument.getElementById(\"mcqGeneralFeedback\");\n\nconst mcqGeneralText =\ndocument.getElementById(\"mcqGeneralText\");\n\nconst mcqGeneralCursor =\ndocument.getElementById(\"mcqGeneralCursor\");\n\nfunction selectMcqWrongOption(){\n\n  mcqWrongOption.classList.add(\"clicking\");\n\n  setTimeout(() => {\n    mcqWrongOption.classList.add(\"selected\");\n  },220);\n\n  setTimeout(() => {\n    mcqWrongOption.classList.remove(\"clicking\");\n  },850);\n\n}\n\nfunction clickMcqSubmit(){\n\n  mcqSubmitButton.classList.add(\"clicked\");\n\n  setTimeout(() => {\n    mcqSubmitButton.classList.remove(\"clicked\");\n  },240);\n\n}\n\nfunction showMcqSpecificFeedback(){\n\n  mcqSpecificFeedback.classList.add(\"show\");\n\n  setTimeout(() => {\n    mcqCrossIcon.classList.add(\"show\");\n  },180);\n\n  setTimeout(() => {\n\n    mcqSpecificCursor.style.display = \"inline-block\";\n\n    typeWriter(mcqSpecificText,mcqSpecificFeedbackText,12,() => {\n\n      mcqSpecificCursor.style.display = \"none\";\n\n      setTimeout(() => {\n        showMcqGeneralFeedback();\n      },650);\n\n    });\n\n  },560);\n\n}\n\nfunction showMcqGeneralFeedback(){\n\n  mcqGeneralFeedback.classList.add(\"show\");\n\n  setTimeout(() => {\n\n    mcqGeneralCursor.style.display = \"inline-block\";\n\n    typeWriter(mcqGeneralText,mcqGeneralFeedbackText,8,() => {\n\n      mcqGeneralCursor.style.display = \"none\";\n\n      setTimeout(() => {\n\n        switchScene(sceneMcq,sceneSaq,() => {\n          startSaqIntro();\n        });\n\n      },2600);\n\n    });\n\n  },600);\n\n}\n\nfunction startMcqAnimation(){\n\n  fitMcqScreen();\n\n  mcqScreen.classList.add(\"show\");\n\n  setTimeout(() => {\n\n    selectMcqWrongOption();\n\n    setTimeout(() => {\n\n      clickMcqSubmit();\n\n      setTimeout(() => {\n\n        showMcqSpecificFeedback();\n\n      },620);\n\n    },1150);\n\n  },1300);\n\n}\n\nfunction startMcqIntro(){\n\n  fitMcqScreen();\n\n  setTimeout(() => {\n\n    typeWriter(mcqIntroTitleText,mcqIntroTitle,44,() => {\n\n      setTimeout(() => {\n\n        mcqIntroTitleCursor.style.display = \"none\";\n\n        setTimeout(() => {\n\n          mcqIntroScreen.classList.add(\"hide\");\n\n          setTimeout(() => {\n            startMcqAnimation();\n          },850);\n\n        },3000);\n\n      },250);\n\n    });\n\n  },700);\n\n}\n\n\/* ============================================================\n   3. SHORT ANSWER FEEDBACK\n============================================================ *\/\n\nconst saqIntroTitle =\n\"Chemistry Specialist\\nMarked Exam Feedback\";\n\nconst saqStudentAnswer =\n\"Magnesium has stronger metallic bonding because it has more atoms packed together and melts at a higher temperature than sodium.\";\n\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 =\ndocument.getElementById(\"saqIntro\");\n\nconst saqIntroTitleText =\ndocument.getElementById(\"saqIntroTitleText\");\n\nconst saqIntroTitleCursor =\ndocument.getElementById(\"saqIntroTitleCursor\");\n\nconst saqStudentText =\ndocument.getElementById(\"saqStudentText\");\n\nconst saqTeacherText =\ndocument.getElementById(\"saqTeacherText\");\n\nconst saqStudentCursor =\ndocument.getElementById(\"saqStudentCursor\");\n\nconst saqTeacherCursor =\ndocument.getElementById(\"saqTeacherCursor\");\n\nconst saqFeedbackBox =\ndocument.getElementById(\"saqTeacherFeedback\");\n\nconst saqScreen =\ndocument.getElementById(\"saqScreen\");\n\nfunction startSaqFeedbackAnimation(){\n\n  fitSaqScreen();\n\n  saqScreen.classList.add(\"show\");\n\n  setTimeout(() => {\n\n    typeWriter(saqStudentText,saqStudentAnswer,27,() => {\n\n      saqStudentCursor.style.display = \"none\";\n\n      setTimeout(() => {\n\n        saqFeedbackBox.classList.add(\"show\");\n        saqTeacherCursor.style.display = \"inline-block\";\n\n        typeWriter(saqTeacherText,saqTeacherFeedbackText,10,() => {\n\n          saqTeacherCursor.style.display = \"none\";\n\n        });\n\n      },650);\n\n    });\n\n  },850);\n\n}\n\nfunction startSaqIntro(){\n\n  fitSaqScreen();\n\n  setTimeout(() => {\n\n    typeWriter(saqIntroTitleText,saqIntroTitle,44,() => {\n\n      setTimeout(() => {\n\n        saqIntroTitleCursor.style.display = \"none\";\n\n        setTimeout(() => {\n\n          saqIntro.classList.add(\"hide\");\n\n          setTimeout(() => {\n\n            startSaqFeedbackAnimation();\n\n          },850);\n\n        },3000);\n\n      },250);\n\n    });\n\n  },700);\n\n}\n\n\/* ============================================================\n   START\n============================================================ *\/\n\ninitialiseOlsVisibilityControlledAnimation();\n<\/script>\n\n\n\n        <\/template>\n      \n        <script>\n          (function(){\n            var startButton = document.getElementById(\"olsCourseAnimationStart002\");\n            var pauseButton = document.getElementById(\"olsCourseAnimationPause002\");\n            var iframe = document.getElementById(\"olsCourseAnimationFrame002\");\n            var template = document.getElementById(\"olsCourseAnimationTemplate002\");\n      \n            if (!startButton || !pauseButton || !iframe || !template) {\n              return;\n            }\n      \n            var olsAnimationPausedFromButton = false;\n      \n            startButton.addEventListener(\"click\", function(){\n              iframe.setAttribute(\"srcdoc\", template.innerHTML);\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              olsAnimationPausedFromButton = false;\n            });\n      \n            pauseButton.addEventListener(\"click\", function(){\n              if (!iframe.contentWindow) {\n                return;\n              }\n      \n              if (!olsAnimationPausedFromButton) {\n                if (typeof iframe.contentWindow.olsPauseAnimation === \"function\") {\n                  iframe.contentWindow.olsPauseAnimation();\n                }\n                olsAnimationPausedFromButton = true;\n                pauseButton.textContent = \"Resume\";\n                pauseButton.setAttribute(\"aria-label\", \"Resume course preview animation\");\n              } else {\n                if (typeof iframe.contentWindow.olsResumeAnimation === \"function\") {\n                  iframe.contentWindow.olsResumeAnimation();\n                }\n                olsAnimationPausedFromButton = false;\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-faq-card\">\n        <h2>FAQs<\/h2>\n        <p>These questions target the most common exam wording for ionisation energy trends down a group.<\/p>\n        <div class=\"ols-faq-list\">\n          <div class=\"ols-faq-item\">\n            <h3>Why does first ionisation energy decrease down a group?<\/h3>\n            <p>First ionisation energy decreases down a group because atoms have more occupied electron shells. The outer electron is further from the nucleus and is shielded more strongly by inner shells, so the attraction to the nucleus is weaker.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>Why does atomic radius increase down a group?<\/h3>\n            <p>Atomic radius increases down a group because each element has an additional main electron shell. This places the outer electron further from the nucleus.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>What is shielding in ionisation energy?<\/h3>\n            <p>Shielding is the reduction in attraction between the nucleus and the outer electron due to repulsion from inner-shell electrons. More inner shells mean greater shielding.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>Why does increased nuclear charge not make ionisation energy increase down a group?<\/h3>\n            <p>Nuclear charge increases down a group because there are more protons. However, the extra occupied shells and increased shielding have a greater effect, so the outer electron is less strongly attracted overall.<\/p>\n          <\/div>\n          <div class=\"ols-faq-item\">\n            <h3>What wording should I use in an exam answer?<\/h3>\n            <p>Use this sequence: more occupied shells, larger atomic radius, more shielding, weaker attraction between the nucleus and the outer electron, less energy needed to remove the electron.<\/p>\n          <\/div>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-related-card\">\n        <h2>Related Topics<\/h2>\n        <p>Build the surrounding knowledge needed for ionisation energy, electron configuration and periodic trends.<\/p>\n        <div class=\"ols-related-grid\">\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/introduction-to-ionisation-energy\/\">Introduction to Ionisation Energy<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/successive-ionisation-energies\/\">Successive Ionisation Energies<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-period\/\">Trends in a Period<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/electron-configuration\/\">Electron Configuration<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/\">Mass Spectrometry<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/\">Bonding &amp; Structure<\/a>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-attribution-card\">\n        <p><strong>Copyright notice:<\/strong> This OLS revision content, including the explanations, layout, diagrams, tables and embedded learning structure, is authored for Online Learning System by Dr. Mohammed Al-Fatah. It may not be copied, reproduced, redistributed or adapted without written permission.<\/p>\n      <\/section>\n\n      <script type=\"application\/ld+json\">\n{\n        \"@context\": \"https:\/\/schema.org\",\n        \"@graph\": [\n                {\n                        \"@type\": \"WebPage\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/\",\n                        \"name\": \"Trends in a Group - Edexcel A Level Chemistry Revision Notes\",\n                        \"description\": \"Edexcel A Level Chemistry revision notes on ionisation energy trends down a group, including atomic radius, shielding, nuclear charge and exam wording.\",\n                        \"inLanguage\": \"en-GB\",\n                        \"isPartOf\": {\n                                \"@type\": \"WebSite\",\n                                \"name\": \"Online Learning System\",\n                                \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/\"\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                        \"about\": [\n                                { \"@type\": \"Thing\", \"name\": \"Ionisation energy\" },\n                                { \"@type\": \"Thing\", \"name\": \"Periodic trends\" },\n                                { \"@type\": \"Thing\", \"name\": \"Atomic radius\" },\n                                { \"@type\": \"Thing\", \"name\": \"Shielding\" }\n                        ]\n                },\n                {\n                        \"@type\": \"BreadcrumbList\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/#breadcrumb\",\n                        \"itemListElement\": [\n                                { \"@type\": \"ListItem\", \"position\": 1, \"name\": \"Revision Notes\", \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\" },\n                                { \"@type\": \"ListItem\", \"position\": 2, \"name\": \"A Level Chemistry\", \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\" },\n                                { \"@type\": \"ListItem\", \"position\": 3, \"name\": \"Edexcel\", \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/\" },\n                                { \"@type\": \"ListItem\", \"position\": 4, \"name\": \"Topic 1 Atomic Structure & The Periodic Table\", \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/\" },\n                                { \"@type\": \"ListItem\", \"position\": 5, \"name\": \"Ionisation Energy\", \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/\" },\n                                { \"@type\": \"ListItem\", \"position\": 6, \"name\": \"Trends in a Group\", \"item\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/\" }\n                        ]\n                },\n                {\n                        \"@type\": \"Course\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/#course\",\n                        \"name\": \"Trends in a Group - Ionisation Energy\",\n                        \"description\": \"Free Edexcel A Level Chemistry revision notes explaining why first ionisation energy decreases down a group using atomic radius, shielding and nuclear attraction.\",\n                        \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/\",\n                        \"provider\": {\n                                \"@type\": \"Organization\",\n                                \"name\": \"Online Learning System\",\n                                \"sameAs\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/\"\n                        },\n                        \"educationalLevel\": \"A Level Chemistry\",\n                        \"teaches\": [\n                                \"Ionisation energy trends down a group\",\n                                \"Atomic radius down a group\",\n                                \"Shielding and nuclear attraction\",\n                                \"Exam wording for periodic trends\"\n                        ]\n                },\n                {\n                        \"@type\": \"FAQPage\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/#faq\",\n                        \"mainEntity\": [\n                                {\n                                        \"@type\": \"Question\",\n                                        \"name\": \"Why does first ionisation energy decrease down a group?\",\n                                        \"acceptedAnswer\": {\n                                                \"@type\": \"Answer\",\n                                                \"text\": \"First ionisation energy decreases down a group because atoms have more occupied electron shells. The outer electron is further from the nucleus and is shielded more strongly by inner shells, so the attraction to the nucleus is weaker.\"\n                                        }\n                                },\n                                {\n                                        \"@type\": \"Question\",\n                                        \"name\": \"Why does atomic radius increase down a group?\",\n                                        \"acceptedAnswer\": {\n                                                \"@type\": \"Answer\",\n                                                \"text\": \"Atomic radius increases down a group because each element has an additional main electron shell. This places the outer electron further from the nucleus.\"\n                                        }\n                                },\n                                {\n                                        \"@type\": \"Question\",\n                                        \"name\": \"What is shielding in ionisation energy?\",\n                                        \"acceptedAnswer\": {\n                                                \"@type\": \"Answer\",\n                                                \"text\": \"Shielding is the reduction in attraction between the nucleus and the outer electron due to repulsion from inner-shell electrons. More inner shells mean greater shielding.\"\n                                        }\n                                },\n                                {\n                                        \"@type\": \"Question\",\n                                        \"name\": \"Why does increased nuclear charge not make ionisation energy increase down a group?\",\n                                        \"acceptedAnswer\": {\n                                                \"@type\": \"Answer\",\n                                                \"text\": \"Nuclear charge increases down a group because there are more protons. However, the extra occupied shells and increased shielding have a greater effect, so the outer electron is less strongly attracted overall.\"\n                                        }\n                                },\n                                {\n                                        \"@type\": \"Question\",\n                                        \"name\": \"What wording should I use in an exam answer?\",\n                                        \"acceptedAnswer\": {\n                                                \"@type\": \"Answer\",\n                                                \"text\": \"Use this sequence: more occupied shells, larger atomic radius, more shielding, weaker attraction between the nucleus and the outer electron, less energy needed to remove the electron.\"\n                                        }\n                                }\n                        ]\n                },\n                {\n                        \"@type\": \"ItemList\",\n                        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/#relatedtopics\",\n                        \"name\": \"Related Ionisation Energy Revision Notes\",\n                        \"itemListElement\": [\n                                {\n                                        \"@type\": \"ListItem\",\n                                        \"position\": 1,\n                                        \"item\": {\n                                                \"@type\": \"Course\",\n                                                \"name\": \"Introduction to Ionisation Energy\",\n                                                \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/introduction-to-ionisation-energy\/\",\n                                                \"description\": \"Revision notes covering first ionisation energy, second ionisation energy and the main factors affecting ionisation energy.\"\n                                        }\n                                },\n                                {\n                                        \"@type\": \"ListItem\",\n                                        \"position\": 2,\n                                        \"item\": {\n                                                \"@type\": \"Course\",\n                                                \"name\": \"Successive Ionisation Energy\",\n                                                \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/successive-ionisation-energies\/\",\n                                                \"description\": \"Revision notes covering successive ionisation energy and how large jumps reveal electronic structure and group number.\"\n                                        }\n                                },\n                                {\n                                        \"@type\": \"ListItem\",\n                                        \"position\": 3,\n                                        \"item\": {\n                                                \"@type\": \"Course\",\n                                                \"name\": \"Trends in a Period\",\n                                                \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-period\/\",\n                                                \"description\": \"Revision notes covering first ionisation energy trends across a period, including Group 2 to Group 3 and Group 5 to Group 6 exceptions.\"\n                                        }\n                                },\n                                {\n                                        \"@type\": \"ListItem\",\n                                        \"position\": 4,\n                                        \"item\": {\n                                                \"@type\": \"Course\",\n                                                \"name\": \"Quantum Model\",\n                                                \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/electron-configuration\/\",\n                                                \"description\": \"Revision notes covering orbitals, subshells and electronic configuration in the quantum model of the atom.\"\n                                        }\n                                },\n                                {\n                                        \"@type\": \"ListItem\",\n                                        \"position\": 5,\n                                        \"item\": {\n                                                \"@type\": \"Course\",\n                                                \"name\": \"Mass Spectrometry\",\n                                                \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/\",\n                                                \"description\": \"Revision notes covering mass spectrometry, relative atomic mass calculations and interpretation of mass spectra.\"\n                                        }\n                                },\n                                {\n                                        \"@type\": \"ListItem\",\n                                        \"position\": 6,\n                                        \"item\": {\n                                                \"@type\": \"Course\",\n                                                \"name\": \"Bonding & Structure\",\n                                                \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/\",\n                                                \"description\": \"Revision notes covering bonding and structure, including ionic, metallic and covalent bonding.\"\n                                        }\n                                }\n                        ]\n                }\n        ]\n}\n      <\/script>\n\n      <div class=\"ols-image-lightbox\" id=\"olsImageLightboxTrendsGroup9ch0\" aria-hidden=\"true\" role=\"dialog\" aria-modal=\"true\" aria-label=\"Expanded revision image\">\n        <div class=\"ols-image-lightbox-inner\">\n          <button class=\"ols-image-lightbox-close\" type=\"button\" aria-label=\"Close enlarged image\">\u00d7<\/button>\n          <img decoding=\"async\" class=\"ols-image-lightbox-img\" src=\"\" alt=\"\">\n        <\/div>\n      <\/div>\n\n      <script>\n        (function(){\n          var page = document.querySelector(\".ols-trends-in-a-group-9ch0-page\");\n          if (!page) return;\n          var lightbox = page.querySelector(\"#olsImageLightboxTrendsGroup9ch0\");\n          if (!lightbox) return;\n          var lightboxImage = lightbox.querySelector(\".ols-image-lightbox-img\");\n          var closeButton = lightbox.querySelector(\".ols-image-lightbox-close\");\n          var clickableImages = page.querySelectorAll(\"img.ols-lightbox-target\");\n          function openLightbox(image) {\n            lightboxImage.src = image.currentSrc || image.src;\n            lightboxImage.alt = image.alt || \"Expanded revision image\";\n            lightbox.classList.add(\"is-open\");\n            lightbox.setAttribute(\"aria-hidden\", \"false\");\n            if (!document.body.dataset.olsPreviousOverflow) { document.body.dataset.olsPreviousOverflow = document.body.style.overflow || \"default\"; }\n            document.body.style.overflow = \"hidden\";\n          }\n          function closeLightbox() {\n            lightbox.classList.remove(\"is-open\");\n            lightbox.setAttribute(\"aria-hidden\", \"true\");\n            lightboxImage.src = \"\";\n            if (document.body.dataset.olsPreviousOverflow) {\n              document.body.style.overflow = document.body.dataset.olsPreviousOverflow === \"default\" ? \"\" : document.body.dataset.olsPreviousOverflow;\n              delete document.body.dataset.olsPreviousOverflow;\n            }\n          }\n          clickableImages.forEach(function(image){ image.addEventListener(\"click\", function(e){ e.preventDefault(); e.stopPropagation(); openLightbox(image); }); });\n          closeButton.addEventListener(\"click\", closeLightbox);\n          lightbox.addEventListener(\"click\", function(e){ if (e.target === lightbox) closeLightbox(); });\n          document.addEventListener(\"keydown\", function(e){ if (e.key === \"Escape\" && lightbox.classList.contains(\"is-open\")) closeLightbox(); });\n        })();\n      <\/script>\n    <\/main>\n  <\/div>\n<\/section>\n","protected":false},"excerpt":{"rendered":"<p>Revision Notes \/ A Level Chemistry \/ Edexcel \/ Topic 1 Atomic Structure &amp; The Periodic Table \/ Ionisation Energy \/ Trends in a Group Trends in a Group A concise revision guide to first ionisation energy trends down a group, including atomic radius, shielding, nuclear charge and why outer electrons become easier to remove. [&hellip;]<\/p>\n","protected":false},"author":12,"featured_media":0,"parent":4516,"menu_order":3,"comment_status":"closed","ping_status":"closed","template":"","meta":{"productId":0,"courseId":0,"footnotes":""},"class_list":["post-4525","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4525","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=4525"}],"version-history":[{"count":0,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4525\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4516"}],"wp:attachment":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/media?parent=4525"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}