{"id":10481,"date":"2026-09-26T11:30:35","date_gmt":"2026-09-26T10:30:35","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/"},"modified":"2026-10-04T23:02:44","modified_gmt":"2026-10-04T22:02:44","slug":"thermal-stability-and-flame-colours","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/","title":{"rendered":"Thermal Stability and Flame Colours"},"content":{"rendered":"\n<section class=\"ols-revision-page ols-redox-groups-page\">\n  <style>\n    .ols-revision-page {\n      --navy: #1C244B;\n      --blue: #2563eb;\n      --soft-blue: #eef4ff;\n      --soft-red: #fff7f7;\n      --soft-purple: #f7f0ff;\n      --soft-green: #f0f7f1;\n      --gold: #c9973a;\n      --grey-text: #667085;\n      --body-text: #1f2937;\n      --border: 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    .ols-revision-page * { box-sizing: border-box; }\n\n    .ols-breadcrumbs { display: flex; flex-wrap: wrap; gap: 8px; margin: 10px 0 22px; font-size: 15px; color: var(--grey-text); }\n    .ols-breadcrumbs a, .ols-breadcrumbs span { color: var(--grey-text); text-decoration: none; font-weight: 600; }\n    .ols-breadcrumbs a { transition: color 0.2s ease, text-decoration-color 0.2s ease; }\n    .ols-breadcrumbs a:hover { color: var(--blue); text-decoration: underline; text-underline-offset: 3px; }\n    .ols-title-card, .ols-note-card, .ols-h5p-card, .ols-related-card { background: #ffffff; border: 1px solid var(--border); border-radius: 28px; box-shadow: var(--shadow); padding: 34px; margin-bottom: 24px; overflow: hidden; }\n    .ols-title-card { background: linear-gradient(135deg, #ffffff 0%, #f8fbff 100%); }\n    .ols-title-card h1 { margin: 0 0 18px; font-size: clamp(36px, 5vw, 58px); line-height: 1.08; font-weight: 800; letter-spacing: -0.04em; color: #111827; }\n    .ols-page-intro { font-size: 19px; line-height: 1.7; font-weight: 300; color: var(--body-text); margin: 0 0 22px; }\n    .ols-badges { display: flex; flex-wrap: wrap; gap: 12px; margin-bottom: 22px; }\n    .ols-badge { display: inline-flex; align-items: center; padding: 9px 14px; border-radius: 999px; background: #ffffff; border: 1px solid var(--border); font-size: 15px; font-weight: 600; color: var(--navy); }\n    .ols-note-card.soft { background: linear-gradient(135deg, #ffffff 0%, var(--soft-red) 100%); }\n    .ols-note-card.purple { background: linear-gradient(135deg, #ffffff 0%, var(--soft-purple) 100%); }\n    .ols-note-title { display: flex; align-items: center; gap: 14px; margin-bottom: 20px; }\n    .ols-note-icon { width: 52px; height: 52px; border-radius: 16px; background: var(--navy); color: #ffffff; display: grid; place-items: center; font-size: 24px; font-weight: 800; flex-shrink: 0; }\n    .ols-note-title h2, .ols-h5p-card h2, .ols-related-card h2 { margin: 0; font-size: clamp(28px, 3.5vw, 42px); line-height: 1.15; font-weight: 800; color: #111827; letter-spacing: -0.03em; }\n    .ols-note-card p, .ols-note-card li, .ols-h5p-card p, .ols-related-card p { font-size: clamp(15px, 1.25vw, 17px); line-height: 1.65; font-weight: 300; color: var(--body-text); }\n    .ols-note-card strong, .ols-h5p-card strong, .ols-related-card strong, .ols-faq-card strong { font-weight: 750; color: var(--navy); }\n    .ols-note-card ul { margin: 0; padding-left: 22px; }\n    .ols-key-box { margin-top: 20px; background: var(--soft-green); border: 1px solid rgba(63, 143, 70, 0.25); border-radius: 20px; padding: 18px 20px; }\n    .ols-key-box p { margin: 0; font-weight: 400; color: var(--navy); }\n    .ols-figure-card { margin: 26px 0 4px; border: 1px solid var(--border); border-radius: 26px; overflow: hidden; background: #ffffff; box-shadow: var(--inner-shadow); }\n    .ols-figure-image { width: 100%; min-height: 390px; background-color: #ffffff; background-image: var(--ols-image); background-repeat: no-repeat; background-position: center; background-size: contain; border-bottom: 1px solid var(--border); }\n    .ols-figure-caption { padding: 22px 26px 24px; background: linear-gradient(135deg, #ffffff, #f8fbff); }\n    .ols-figure-caption h3 { margin: 0 0 8px; color: var(--navy); font-size: clamp(21px, 2vw, 30px); line-height: 1.25; font-weight: 800; font-style: italic; }\n    .ols-figure-caption p { margin: 0; color: #5f6b85; font-size: clamp(16px, 1.4vw, 19px); line-height: 1.65; font-weight: 300; font-style: italic; }\n    .ols-table-wrap { overflow-x: auto; border-radius: 22px; border: 1px solid var(--border); background: #ffffff; margin-top: 18px; }\n    .ols-table { width: 100%; border-collapse: collapse; min-width: 680px; }\n    .ols-table th { background: var(--navy); color: #ffffff; padding: 14px 16px; text-align: left; font-size: 15px; font-weight: 700; }\n    .ols-table td { padding: 14px 16px; border-bottom: 1px solid var(--border); font-size: 15px; color: var(--body-text); vertical-align: top; }\n    .ols-table tr:last-child td { border-bottom: none; }\n    .ols-definition-box { background: linear-gradient(135deg, #ffffff, var(--soft-purple)); border: 2px dashed rgba(122, 62, 157, 0.35); border-radius: 24px; padding: 26px; margin-top: 22px; display: grid; grid-template-columns: 1fr; gap: 16px; align-items: center; }\n    .ols-definition-circle { width: 105px; height: 105px; border-radius: 50%; background: linear-gradient(135deg, #9b59b6, #6f3d96); color: white; display: grid; place-items: center; font-size: 28px; font-weight: 800; text-align: center; margin: 0 auto; }\n    .ols-h5p-card { background: linear-gradient(135deg, #ffffff 0%, #f7f0ff 100%); }\n    .ols-h5p-frame { margin-top: 22px; padding: 18px; border-radius: 24px; background: #ffffff; border: 1px solid var(--border); box-shadow: inset 0 0 0 1px rgba(28, 36, 75, 0.03); }\n    .ols-infographic-full { width: 100%; margin: 6px 0 30px; }\n    .ols-infographic-full-frame { width: 100%; border-radius: 22px; overflow: hidden; box-shadow: 0 18px 42px rgba(28, 36, 75, 0.13); background: #ffffff; }\n    .ols-infographic-full-frame img { width: 100%; height: auto; display: block; }\n    .ols-related-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; margin-top: 18px; }\n    .ols-related-item { border: 1px solid var(--border); border-radius: 18px; padding: 18px; background: #ffffff; color: var(--navy); text-decoration: none; font-weight: 600; line-height: 1.5; transition: transform 0.2s ease, box-shadow 0.2s ease; }\n    .ols-related-item:hover { transform: translateY(-2px); box-shadow: 0 10px 22px rgba(28, 36, 75, 0.08); }\n    .ols-unlock { background: linear-gradient(135deg, var(--navy), #0f4fa8); border-radius: 30px; padding: 36px; color: #ffffff; box-shadow: var(--shadow); text-align: center; margin: 30px 0 24px; }\n    .ols-unlock h2 { margin: 0 0 12px; font-size: clamp(30px, 4vw, 46px); line-height: 1.15; font-weight: 800; color: #ffffff; text-align: center; }\n    .ols-unlock p { margin: 0 auto 24px; max-width: 700px; font-size: 20px; line-height: 1.6; font-weight: 300; text-align: center; color: #ffffff; }\n    .ols-cta-button { display: inline-flex; align-items: center; justify-content: center; padding: 14px 26px; border-radius: 999px; background: #ffffff; color: var(--navy); text-decoration: none; font-weight: 700; }\n\n    @media (max-width: 1050px) {\n      .ols-main { max-width: none; }\n      .ols-related-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }\n    }\n\n    @media (max-width: 760px) {\n      .ols-title-card, .ols-note-card, .ols-h5p-card, .ols-related-card, .ols-unlock { padding: 24px 18px; border-radius: 22px; }\n      .ols-note-title { align-items: flex-start; }\n      .ols-figure-card { border-radius: 22px; }\n      .ols-figure-image { min-height: 250px; }\n      .ols-figure-caption { padding: 18px; }\n      .ols-topic-list, .ols-related-grid { grid-template-columns: 1fr; }\n      .ols-infographic-full { margin: 0 0 26px; }\n      .ols-infographic-full-frame { border-radius: 18px; }\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    .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    .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    .ols-author-content { min-width: 0; }\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    .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    .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    .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    }\n    .ols-linkedin-icon { width: 18px; height: 18px; display: block; flex-shrink: 0; }\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      box-sizing: border-box;\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    .ols-attribution-card strong { font-weight: 700; color: #1C244B; }\n      .ols-note-card h3 { margin: 22px 0 8px; font-size: 18px; line-height: 1.25; font-weight: 500; color: var(--navy); }\n  \n    .ols-figure-placeholder .ols-placeholder-box { border: 2px dashed #c9973a; background: #fffaf0; border-radius: 16px; padding: 26px 22px; font-weight: 700; color: #7a4b12; text-align: center; line-height: 1.6; }\n    .ols-figure-placeholder .ols-figure-image { background: transparent; }\n    .ols-figure-placeholder { background: #ffffff; border: 1px solid rgba(28, 36, 75, 0.12); border-radius: 22px; padding: 14px; margin: 18px 0 6px; }\n    .ols-figure-placeholder .ols-figure-caption p { margin: 10px 0 0; font-size: 14px; color: #667085; text-align: center; }\n\n    \/* inline checks (H5P re-flow, Sep 2026) *\/\n    .ols-h5p-card.ols-h5p-inline { padding: 26px 28px; border-left: 6px solid #7c3aed; }\n    .ols-h5p-card.ols-h5p-inline h2 { font-size: clamp(20px, 2.2vw, 27px); letter-spacing: -0.02em; }\n    .ols-h5p-card.ols-h5p-inline > p { margin: 8px 0 0; }\n    .ols-h5p-card.ols-h5p-inline .ols-h5p-frame { margin-top: 16px; padding: 14px; border-radius: 20px; }\n    .ols-h5p-kicker { display: inline-block; margin-bottom: 10px; padding: 5px 12px; border-radius: 999px; background: #ede9fe; color: #5b21b6; font-size: 12px; font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase; }\n    .ols-h5p-card.ols-h5p-recap { border-left-color: #c9973a; background: linear-gradient(135deg, #ffffff 0%, #fff8e8 100%); }\n    .ols-h5p-recap .ols-h5p-kicker { background: #fdf0d2; color: #8a5a00; }\n    @media (max-width: 760px) { .ols-h5p-card.ols-h5p-inline { padding: 20px 16px; } }\n\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.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.ols-faq-card h2,\n    .ols-quicksnap-card h2 {\n      margin-bottom: 14px;\n    }\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.ols-faq-card strong,\n    .ols-quicksnap-card strong {\n      font-weight: 700;\n      color: var(--navy);\n    }\n.ols-faq-list {\n      display: grid;\n      gap: 14px;\n      margin-top: 18px;\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.ols-faq-item h3 {\n      margin: 0 0 8px;\n      font-size: 20px;\n      line-height: 1.3;\n      color: var(--navy);\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.ols-faq-card,\n      .ols-quicksnap-card,\n      .ols-attribution-card {\n        padding: 24px 18px;\n        border-radius: 22px;\n      }\n  <\/style>\n\n    <aside class=\"ols-sidebar\">\n  <div class=\"ols-sidebar-header\">\n    <h3>Revision Notes<\/h3>\n    <p>A Level Chemistry<\/p>\n  <\/div>\n\n  <div class=\"ols-topic-group\">\n    <h4>Topic 8 Redox &amp; Groups 1, 2 and 7<\/h4>\n\n    <ul class=\"ols-topic-list\">\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/\">Topic 8 Overview<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/\">Topic 8A Redox Chemistry<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/oxidation-numbers\/\">Oxidation Numbers<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/electron-transfer-and-half-equations\/\">Electron Transfer and Half-Equations<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/disproportionation\/\">Disproportionation<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8a-redox-chemistry\/redox-classification\/\">Redox Classification<\/a>\n          <\/li>\n        <\/ul>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/\">Topic 8B Groups 1 and 2<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/trends-down-groups-1-and-2\/\">Trends Down Groups 1 and 2<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/reactions-of-the-group-1-and-2-elements\/\">Reactions of the Group 1 and 2 Elements<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/oxides-hydroxides-and-carbonates\/\">Oxides, Hydroxides and Carbonates<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/solubility-trends-and-the-sulfate-test\/\">Solubility Trends and the Sulfate Test<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/\">Thermal Stability and Flame Colours<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/tests-for-ions\/\">Tests for Ions<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/titrations-and-measurement-uncertainty\/\">Titrations and Measurement Uncertainty<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-3-concentration-of-hcl-by-titration\/\">Core Practical 3<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/cp-4-preparation-of-a-standard-solution\/\">Core Practical 4<\/a>\n          <\/li>\n        <\/ul>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/\">Topic 8C Group 7<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/trends-in-the-halogens\/\">Trends in the Halogens<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/halogens-as-oxidising-agents\/\">Halogens as Oxidising Agents<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/disproportionation-reactions-of-chlorine\/\">Disproportionation Reactions of Chlorine<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8c-group-7\/halide-ions-reducing-agents-and-tests\/\">Halide Ions: Reducing Agents and Tests<\/a>\n          <\/li>\n        <\/ul>\n      <\/li>\n    <\/ul>\n  <\/div>\n\n  <div class=\"ols-topic-group\">\n    <h4>Other Topics<\/h4>\n\n    <ul class=\"ols-topic-list\">\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-6-energetics\/\">Topic 6 Energetics<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-7-intermolecular-forces\/\">Topic 7 Intermolecular Forces<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-2-atomic-structure-and-the-periodic-table\/\">Topic 2 Atomic Structure &amp; The Periodic Table<\/a>\n      <\/li>\n      <li>\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/core-practicals\/\">Core Practicals<\/a>\n      <\/li>\n    <\/ul>\n  <\/div>\n<\/aside>\n\n<script>\r\n(function() {\r\n  function normalisePath(path) {\r\n    return String(path || '')\r\n      .split('?')[0]\r\n      .split('#')[0]\r\n      .replace(\/\\\/+$\/, '')\r\n      .toLowerCase();\r\n  }\r\n\r\n  function highlightActive() {\r\n    var sidebar = document.querySelector('.ols-sidebar');\r\n    if (!sidebar) return false;\r\n\r\n    var currentPath = normalisePath(window.location.pathname);\r\n    var links = sidebar.querySelectorAll('a[href]');\r\n    var matched = null;\r\n    var matchedLength = 0;\r\n\r\n    sidebar.querySelectorAll('.active, .active-main, .parent-active').forEach(function(item) {\r\n      item.classList.remove('active', 'active-main', 'parent-active');\r\n    });\r\n\r\n    sidebar.querySelectorAll('a[data-ols-disabled-parent=\"1\"], a[aria-current]').forEach(function(a) {\r\n      a.removeAttribute('aria-current');\r\n      a.removeAttribute('tabindex');\r\n      a.removeAttribute('data-ols-disabled-parent');\r\n    });\r\n\r\n    links.forEach(function(a) {\r\n      try {\r\n        var href = a.getAttribute('href');\r\n\r\n        if (!href || href === '#' || href.charAt(0) === '#') {\r\n          return;\r\n        }\r\n\r\n        var linkPath = normalisePath(new URL(href, window.location.origin).pathname);\r\n\r\n        if (!linkPath) {\r\n          return;\r\n        }\r\n\r\n        if (currentPath === linkPath || currentPath.indexOf(linkPath + '\/') === 0) {\r\n          if (linkPath.length > matchedLength) {\r\n            matched = a;\r\n            matchedLength = linkPath.length;\r\n          }\r\n        }\r\n      } catch(e) {}\r\n    });\r\n\r\n    if (matched) {\r\n      var matchedLi = matched.closest('li');\r\n      var parentSub = matched.closest('.ols-subtopic-list');\r\n\r\n      if (parentSub) {\r\n        if (matchedLi) {\r\n          matchedLi.classList.add('active');\r\n          matched.setAttribute('aria-current', 'page');\r\n        }\r\n\r\n        var parentLi = parentSub.closest('li');\r\n\r\n        if (parentLi) {\r\n          parentLi.classList.add('parent-active', 'active-main');\r\n\r\n          var parentLink = parentLi.querySelector(':scope > a');\r\n\r\n          if (parentLink) {\r\n            parentLink.setAttribute('aria-current', 'true');\r\n            parentLink.setAttribute('tabindex', '-1');\r\n            parentLink.setAttribute('data-ols-disabled-parent', '1');\r\n          }\r\n        }\r\n      } else {\r\n        if (matchedLi) {\r\n          matchedLi.classList.add('parent-active', 'active-main');\r\n          matched.setAttribute('aria-current', 'page');\r\n          matched.setAttribute('tabindex', '-1');\r\n          matched.setAttribute('data-ols-disabled-parent', '1');\r\n        }\r\n      }\r\n    }\r\n\r\n    return true;\r\n  }\r\n\r\n  if (!highlightActive()) {\r\n    document.addEventListener('DOMContentLoaded', highlightActive);\r\n  }\r\n})();\r\n<\/script>\r\n\n\n    <main class=\"ols-main\">\n\n      <!-- BREADCRUMBS - updated with full path and correct links -->\n      <nav class=\"ols-breadcrumbs\" aria-label=\"Breadcrumb\">\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\">Revision Notes<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\">A Level Chemistry<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/\">Edexcel International<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/\">Topic 8 Redox Chemistry and Groups 1, 2 and 7<\/a> \/\n<a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/\">Topic 8B Groups 1 and 2<\/a> \/\n<span>Thermal Stability and Flame Colours<\/span>\n<\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Thermal Stability and Flame Colours<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to the thermal decomposition of the Group 1 and 2 nitrates and carbonates, the trend in stability explained by cation size, charge and polarisation, how to show the patterns experimentally, and the flame colours and their cause.<\/p>\n        <div class=\"ols-badges\">\n<div class=\"ols-badge\">Exam board: Edexcel International<\/div>\n<div class=\"ols-badge\">Unit 2: WCH12\/01<\/div>\n<div class=\"ols-badge\">Topic 8B Groups 1 and 2<\/div>\n<\/div>\n        <div class=\"ols-author\">\n\n    <img decoding=\"async\"\n      class=\"ols-author-avatar-img\"\n      src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Author-Profile.jpeg\"\n      alt=\"Dr. Mohammed Al-Fatah\"\n    >\n\n    <div class=\"ols-author-content\">\n\n      <h2 class=\"ols-author-title\">\n        Written by: Dr. Mohammed Al-Fatah\n      <\/h2>\n\n      <p class=\"ols-author-description\">\n        Chemistry specialist revision notes for A Level Chemistry.\n      <\/p>\n\n      <a class=\"ols-linkedin-pill\" href=\"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\" target=\"_blank\" rel=\"noopener noreferrer\">\n        <svg class=\"ols-linkedin-icon\" viewBox=\"0 0 24 24\" fill=\"currentColor\" aria-hidden=\"true\">\n          <path d=\"M4.98 3.5C4.98 4.88 3.86 6 2.48 6S0 4.88 0 3.5 1.12 1 2.48 1s2.5 1.12 2.5 2.5zM.5 8h4V24h-4V8zm7 0h3.8v2.2h.1c.5-.9 1.8-2.2 3.9-2.2 4.2 0 5 2.8 5 6.4V24h-4v-7.6c0-1.8 0-4.2-2.6-4.2s-3 2-3 4v7.8h-4V8z\"\/>\n        <\/svg>\n        View LinkedIn Profile\n      <\/a>\n\n    <\/div>\n\n  <\/div>\n      <\/header>\n\n      <article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">1<\/div>\n<h2>Thermal Decomposition of the Carbonates<\/h2>\n<\/div>\n<p>On strong heating a metal carbonate breaks down to the metal oxide and carbon dioxide. The <strong>Group 2 carbonates all decompose<\/strong> in a Bunsen flame, and the temperature needed rises down the group.<\/p>\n<div class=\"ols-table-wrap\"><table class=\"ols-table\"><thead><tr><th>Carbonate<\/th><th>Decomposes at about<\/th><\/tr><\/thead><tbody><tr><td><strong>Magnesium carbonate<\/strong><\/td><td>350 \u00b0C<\/td><\/tr><tr><td><strong>Calcium carbonate<\/strong><\/td><td>840 \u00b0C<\/td><\/tr><tr><td><strong>Strontium carbonate<\/strong><\/td><td>1100 \u00b0C<\/td><\/tr><tr><td><strong>Barium carbonate<\/strong><\/td><td>1300 \u00b0C<\/td><\/tr><\/tbody><\/table><\/div>\n<p>MgCO\u2083 \u2192 MgO + CO\u2082 &nbsp;&nbsp; CaCO\u2083 \u2192 CaO + CO\u2082<\/p>\n<p>The <strong>Group 1 carbonates are more stable<\/strong>. Sodium and potassium carbonate do not decompose at Bunsen temperatures at all; only lithium carbonate, whose ion is the smallest, breaks down: Li\u2082CO\u2083 \u2192 Li\u2082O + CO\u2082.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Key idea:<\/strong> Thermal stability increases down each group, and Group 1 carbonates are more stable than the Group 2 carbonates beside them.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">2<\/div>\n<h2>Thermal Decomposition of the Nitrates<\/h2>\n<\/div>\n<p>The nitrates show the same pattern, but the products differ between the groups. Most <strong>Group 1 nitrates<\/strong> decompose only to the nitrite and oxygen:<\/p>\n<p>2NaNO\u2083 \u2192 2NaNO\u2082 + O\u2082 &nbsp;&nbsp; 2KNO\u2083 \u2192 2KNO\u2082 + O\u2082<\/p>\n<p>The <strong>Group 2 nitrates<\/strong>, and again lithium nitrate, decompose further to the oxide, nitrogen dioxide and oxygen. The brown fumes of nitrogen dioxide are the sign of this reaction:<\/p>\n<p>2Mg(NO\u2083)\u2082 \u2192 2MgO + 4NO\u2082 + O\u2082 &nbsp;&nbsp; 4LiNO\u2083 \u2192 2Li\u2082O + 4NO\u2082 + O\u2082<\/p>\n<p>The temperature needed rises down Group 2, as with the carbonates.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Exam focus:<\/strong> Learn both nitrate equations. A Group 2 nitrate gives three products; a Group 1 nitrate (other than lithium) gives two.<\/p>\n<\/div>\n<div class=\"ols-figure-card ols-zoom-pop\">\n<div class=\"ols-figure-image\">\n<a class=\"ols-image-fullscreen-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/t8x-nitrateheat.jpg\" target=\"_blank\" rel=\"noopener\" aria-label=\"Open image fullscreen\">\n<img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/t8x-nitrateheat.jpg\" alt=\"Two-lane poster comparing Group 1 nitrates giving nitrite and oxygen with Group 2 nitrates giving oxide, NO\u2082 and oxygen.\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/t8x-nitrateheat.jpg\">\n<\/a>\n<\/div>\n<div class=\"ols-figure-caption\"><p>Most Group 1 nitrates lose only oxygen to form the nitrite, but Group 2 nitrates and lithium nitrate break down further to the oxide, brown nitrogen dioxide and oxygen.<\/p><\/div>\n<\/div>\n<\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Check: Decomposition Products<\/h2>\n<p>Write the decomposition equation and name the gases for carbonates and nitrates not shown above.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-875\" class=\"h5p-iframe\" data-content-id=\"875\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Redox and Groups Fill In: Decomposition Products\"><\/iframe><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card purple\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">3<\/div>\n<h2>Why the Trend Exists: Polarisation<\/h2>\n<\/div>\n<p>The carbonate and nitrate ions are large anions with electron density spread over several oxygen atoms.<\/p>\n<p>A small, highly charged cation has a high <strong>charge density<\/strong> and pulls that electron cloud towards itself, <strong>polarising<\/strong> the anion.<\/p>\n<p>The distortion weakens the C\u2013O or N\u2013O bonds, so less energy is needed to break the ion apart, and the compound decomposes at a lower temperature.<\/p>\n<p>Down each group the cation gets larger, its charge density falls, it polarises the anion less, and the compound is <strong>more stable<\/strong>.<\/p>\n<p>Across from Group 1 to Group 2 the charge doubles, so a 2+ ion polarises far more than a 1+ ion of similar size. This is why Group 2 carbonates and nitrates are the less stable set.<\/p>\n<!-- 3D card: group2-thermal-stability (26 Sep 2026) -->\n<!-- Copyright (c) 2026 Dr. Mohammed Al-Fatah, onlinelearningsystem.net. All rights reserved. -->\n<section class=\"ols-g2c-001\" id=\"olsG2c001\">\n<style>\n@import url('https:\/\/fonts.googleapis.com\/css2?family=Poppins:wght@300;400;500;600&display=swap');\n\n.ols-g2c-001{\n  font-family:'Poppins',system-ui,-apple-system,'Segoe UI',Roboto,Helvetica,Arial,sans-serif;\n  color:#1C244B; background:#ffffff;\n  border:1px solid rgba(28,36,75,0.14);\n  border-radius:28px;\n  box-shadow:0 18px 45px rgba(28,36,75,0.10);\n  padding:44px; margin:26px auto; max-width:980px;\n  box-sizing:border-box; -webkit-font-smoothing:antialiased;\n}\n.ols-g2c-001 *{box-sizing:border-box;}\n\n.ols-g2c-001 .g2c-head{margin:0 0 22px;}\n.ols-g2c-001 h2.g2c-title{\n  font-size:26px; line-height:1.25; font-weight:600; letter-spacing:-0.012em;\n  margin:0 0 9px; color:#1C244B;\n}\n.ols-g2c-001 p.g2c-sub{\n  font-size:14.5px; line-height:1.62; font-weight:300; color:#4a5270;\n  margin:0; max-width:66ch;\n}\n\n.ols-g2c-001 .g2c-stage{\n  position:relative; width:100%; height:560px;\n  background:#ffffff; border:1px solid rgba(28,36,75,0.12);\n  border-radius:18px; overflow:hidden;\n}\n.ols-g2c-001 .g2c-canvas{\n  display:block; width:100%; height:100%;\n  touch-action:none; cursor:grab; background:#ffffff;\n}\n.ols-g2c-001 .g2c-canvas.is-drag{cursor:grabbing;}\n.ols-g2c-001 .g2c-overlay{position:absolute; inset:0; pointer-events:none; overflow:hidden;}\n\n.ols-g2c-001 .g2c-lab{\n  position:absolute; left:0; top:0; transform:translate(-50%,-50%);\n  white-space:nowrap; font-size:12.5px; font-weight:500; line-height:1;\n  padding:5px 10px; background:rgba(255,255,255,0.93);\n  border:1px solid rgba(28,36,75,0.16); border-radius:999px;\n  color:#1C244B; will-change:transform;\n}\n.ols-g2c-001 .g2c-lab.l-dom{border-color:rgba(59,120,220,0.55); color:#1d4fb0;}\n.ols-g2c-001 .g2c-lab.l-mol{border-color:rgba(28,36,75,0.32); color:#1C244B;}\n.ols-g2c-001 .g2c-lab.l-ion{font-size:13px; font-weight:600; border-color:rgba(28,36,75,0.32); color:#1C244B;}\n.ols-g2c-001 .g2c-lab.l-prod{font-size:12.5px; font-weight:600; border-color:rgba(201,150,28,0.75); color:#8a6410;}\n.ols-g2c-001 .g2c-lab.l-rul{font-size:11.5px; font-weight:600; padding:2px 7px; color:#1C244B; border-color:rgba(28,36,75,0.5); background:#ffffff;}\n.ols-g2c-001 .g2c-lab.l-ang{font-size:13.5px; font-weight:600; border-color:rgba(201,150,28,0.75); color:#8a6410; background:#ffffff;}\n\n.ols-g2c-001 .g2c-caption{\n  position:absolute; left:14px; top:14px; max-width:60%;\n  font-size:12px; font-weight:500; color:#4a5270; line-height:1.35;\n  background:rgba(255,255,255,0.92); padding:6px 12px;\n  border-radius:14px; border:1px solid rgba(28,36,75,0.12);\n}\n.ols-g2c-001 .g2c-hint{\n  position:absolute; right:14px; top:14px;\n  font-size:11.5px; font-weight:400; color:#8b92a8;\n  background:rgba(255,255,255,0.9); padding:5px 11px;\n  border-radius:999px; border:1px solid rgba(28,36,75,0.10);\n}\n.ols-g2c-001 .g2c-badges{\n  position:absolute; right:14px; bottom:14px; max-width:58%;\n  display:flex; flex-direction:column; align-items:flex-end; gap:6px;\n}\n.ols-g2c-001 .g2c-badge{\n  font-size:12px; font-weight:500; color:#1C244B; line-height:1.35; text-align:right;\n  background:rgba(255,255,255,0.95); padding:5px 12px;\n  border-radius:14px; border:1px solid rgba(28,36,75,0.22);\n}\n.ols-g2c-001 .g2c-badge.b-eq{font-size:13.5px; font-weight:600; border-color:rgba(201,150,28,0.75);}\n.ols-g2c-001 .g2c-badge.b-shape{font-size:14px; font-weight:600; border-color:rgba(201,150,28,0.75);}\n.ols-g2c-001 .g2c-badges.hide{display:none;}\n\n.ols-g2c-001 .g2c-stack{\n  position:absolute; left:14px; top:52px; max-width:62%;\n  display:flex; flex-direction:column; align-items:flex-start; gap:6px; pointer-events:none;\n}\n.ols-g2c-001 .g2c-read{\n  display:flex; flex-direction:column; gap:3px;\n  background:rgba(255,255,255,0.94); padding:7px 12px;\n  border-radius:14px; border:1px solid rgba(28,36,75,0.14);\n}\n.ols-g2c-001 .r-line{font-size:12.5px; font-weight:500; color:#1C244B; line-height:1.4; white-space:nowrap;}\n.ols-g2c-001 .r-line b{font-weight:600;}\n.ols-g2c-001 .r-hot b{color:#c0352d;}\n.ols-g2c-001 .r-line span{margin-left:8px; font-size:11.5px; font-weight:400; color:#7d8399;}\n.ols-g2c-001 .g2c-panel{\n  position:absolute; left:50%; bottom:14px; transform:translateX(-50%);\n  font-size:14.5px; font-weight:600; color:#1C244B; white-space:nowrap;\n  background:#ffffff; padding:8px 16px;\n  border-radius:14px; border:1.5px solid rgba(201,150,28,0.8);\n  box-shadow:0 6px 18px rgba(28,36,75,0.08);\n}\n.ols-g2c-001 .g2c-panel .neg{color:#8a6410;}\n.ols-g2c-001 .g2c-read.hide,.ols-g2c-001 .g2c-panel.hide{display:none;}\n\n.ols-g2c-001 .g2c-controls{margin-top:20px; display:flex; flex-direction:column; gap:12px;}\n.ols-g2c-001 .g2c-row{display:flex; align-items:center; gap:10px; flex-wrap:wrap;}\n.ols-g2c-001 .g2c-rowlab{font-size:12px; font-weight:500; color:#6b7290; min-width:100px; flex:0 0 auto;}\n\n.ols-g2c-001 .g2c-seg{\n  display:inline-flex; border:1px solid rgba(28,36,75,0.16);\n  border-radius:12px; overflow:hidden; background:#fbfbfd; flex-wrap:wrap;\n}\n.ols-g2c-001 .g2c-seg button{\n  font-family:inherit; font-size:14px; font-weight:500; color:#3c4463;\n  background:transparent; border:0; border-right:1px solid rgba(28,36,75,0.12);\n  padding:9px 18px; cursor:pointer; transition:background .15s, color .15s;\n}\n.ols-g2c-001 .g2c-seg button:last-child{border-right:0;}\n.ols-g2c-001 .g2c-seg button:hover{background:rgba(37,99,235,0.06);}\n.ols-g2c-001 .g2c-seg button[aria-pressed=\"true\"]{background:#2563eb; color:#fff;}\n.ols-g2c-001 .g2c-seg button:focus-visible{outline:2px solid #2563eb; outline-offset:-2px;}\n\n.ols-g2c-001 .g2c-pill{\n  font-family:inherit; font-size:13px; font-weight:500; color:#3c4463;\n  background:#fbfbfd; border:1px solid rgba(28,36,75,0.16);\n  border-radius:999px; padding:8px 16px; cursor:pointer;\n  display:inline-flex; align-items:center; gap:8px;\n  transition:background .15s, border-color .15s, color .15s;\n}\n.ols-g2c-001 .g2c-pill:hover{border-color:rgba(37,99,235,0.4);}\n.ols-g2c-001 .g2c-pill:focus-visible{outline:2px solid #2563eb; outline-offset:2px;}\n\n.ols-g2c-001 .g2c-info{\n  margin-top:22px; padding:22px 24px;\n  border:1px solid rgba(28,36,75,0.12); border-radius:16px; background:#fbfbfd;\n}\n.ols-g2c-001 .g2c-info h3{margin:0 0 8px; font-size:15.5px; font-weight:600; color:#1C244B;}\n.ols-g2c-001 .g2c-info p{margin:0; font-size:14px; line-height:1.68; font-weight:300; color:#41496a; max-width:74ch;}\n.ols-g2c-001 .g2c-facts{\n  margin-top:16px; display:flex; gap:26px; flex-wrap:wrap;\n  padding-top:16px; border-top:1px solid rgba(28,36,75,0.10);\n}\n.ols-g2c-001 .g2c-fact{min-width:110px;}\n.ols-g2c-001 .g2c-fact span{display:block; font-size:11.5px; color:#7d8399; font-weight:400; margin-bottom:3px;}\n.ols-g2c-001 .g2c-fact strong{display:block; font-size:15px; font-weight:600; color:#1C244B;}\n\n.ols-g2c-001 .g2c-key{\n  margin-top:16px; display:flex; gap:20px; flex-wrap:wrap;\n  font-size:12.5px; font-weight:400; color:#5a6180;\n}\n.ols-g2c-001 .g2c-key i{\n  display:inline-block; width:13px; height:13px; border-radius:3px;\n  margin-right:7px; vertical-align:-2px; border:1px solid rgba(28,36,75,0.18);\n}\n\n@media (max-width:760px){\n  .ols-g2c-001{padding:26px; border-radius:22px;}\n  .ols-g2c-001 h2.g2c-title{font-size:20.5px;}\n  .ols-g2c-001 p.g2c-sub{font-size:13.5px;}\n  .ols-g2c-001 .g2c-stage{height:420px;}\n  .ols-g2c-001 .g2c-rowlab{min-width:100%;}\n  .ols-g2c-001 .g2c-seg button{padding:9px 13px; font-size:13px;}\n  .ols-g2c-001 .g2c-lab{font-size:10.5px; padding:4px 8px;}\n  .ols-g2c-001 .g2c-caption{font-size:10.5px; padding:5px 9px; max-width:64%;}\n  .ols-g2c-001 .g2c-badge{font-size:10.5px; padding:4px 9px;}\n  .ols-g2c-001 .g2c-badge.b-eq{font-size:13.5px; font-weight:600; border-color:rgba(201,150,28,0.75);}\n.ols-g2c-001 .g2c-badge.b-shape{font-size:12px;}\n  .ols-g2c-001 .g2c-badges{max-width:62%;}\n  .ols-g2c-001 .g2c-info{padding:18px;}\n  .ols-g2c-001 .g2c-stack{top:auto; bottom:auto; top:48px; max-width:72%;}\n  .ols-g2c-001 .r-line{font-size:10.5px;}\n  .ols-g2c-001 .r-line{white-space:normal;}\n  .ols-g2c-001 .g2c-lab.l-ion,.ols-g2c-001 .g2c-lab.l-prod{font-size:10.5px;}\n  .ols-g2c-001 .g2c-lab.l-rul{font-size:9.5px; padding:1px 5px;}\n  .ols-g2c-001 .g2c-badge.b-eq{font-size:11px;}\n  .ols-g2c-001 .g2c-read{padding:5px 9px;}\n  .ols-g2c-001 .g2c-panel{left:auto; right:14px; transform:none; font-size:11px; padding:6px 10px;}\n}\n@media (max-width:560px){\n  .ols-g2c-001 .g2c-hint{display:none;}\n  .ols-g2c-001 .g2c-caption{max-width:none; right:14px;}\n}\n@media (prefers-reduced-motion:reduce){\n  .ols-g2c-001 .g2c-seg button,.ols-g2c-001 .g2c-pill{transition:none;}\n}\n\n.ols-cc-g2c-001{\n  font-family:'Poppins',system-ui,-apple-system,'Segoe UI',Roboto,Helvetica,Arial,sans-serif;\n  margin:10px auto 0; text-align:center; font-size:11px; font-style:italic; color:#aab0c0;\n}\n.ols-cc-g2c-001 a{color:#aab0c0; text-decoration:none;}\n.ols-cc-g2c-001 a:hover{text-decoration:underline;}\n<\/style>\n\n<div class=\"g2c-head\">\n  <h2 class=\"g2c-title\">Polarisation and the Thermal Stability of Group 2 Carbonates<\/h2>\n  <p class=\"g2c-sub\">Compare how strongly Mg<sup>2+<\/sup>, Ca<sup>2+<\/sup>, Sr<sup>2+<\/sup> and Ba<sup>2+<\/sup> distort a carbonate ion, and see why a less polarised anion needs a higher temperature to break up.<\/p>\n<\/div>\n\n<div class=\"g2c-stage\" id=\"g2cStage\">\n  <canvas class=\"g2c-canvas\" id=\"g2cCanvas\"><\/canvas>\n  <div class=\"g2c-overlay\" id=\"g2cOverlay\"><\/div>\n  <div class=\"g2c-caption\" id=\"g2cCaption\"><\/div>\n  <div class=\"g2c-hint\" id=\"g2cHint\">Drag to rotate<\/div>\n  <div class=\"g2c-stack\"><div class=\"g2c-read\" id=\"g2cRead\"><\/div><\/div>\n  <div class=\"g2c-badges\" id=\"g2cBadges\"><\/div>\n<\/div>\n\n<div class=\"g2c-controls\">\n  <div class=\"g2c-row\">\n    <span class=\"g2c-rowlab\">Cation<\/span>\n    <div class=\"g2c-seg\" role=\"group\" aria-label=\"Cation\">\n      <button type=\"button\" data-c=\"Mg\" aria-pressed=\"true\">Mg<sup>2+<\/sup><\/button>\n      <button type=\"button\" data-c=\"Ca\" aria-pressed=\"false\">Ca<sup>2+<\/sup><\/button>\n      <button type=\"button\" data-c=\"Sr\" aria-pressed=\"false\">Sr<sup>2+<\/sup><\/button>\n      <button type=\"button\" data-c=\"Ba\" aria-pressed=\"false\">Ba<sup>2+<\/sup><\/button>\n    <\/div>\n  <\/div>\n\n  <div class=\"g2c-row\">\n    <span class=\"g2c-rowlab\">Step<\/span>\n    <div class=\"g2c-seg\" role=\"group\" aria-label=\"Step\">\n      <button type=\"button\" data-step=\"1\" aria-pressed=\"true\">Ions<\/button>\n      <button type=\"button\" data-step=\"2\" aria-pressed=\"false\">Polarise<\/button>\n      <button type=\"button\" data-step=\"3\" aria-pressed=\"false\">Decompose<\/button>\n      <button type=\"button\" data-step=\"4\" aria-pressed=\"false\">Nitrates<\/button>\n    <\/div>\n  <\/div>\n\n  <div class=\"g2c-row\">\n    <span class=\"g2c-rowlab\">View<\/span>\n    <button type=\"button\" class=\"g2c-pill\" id=\"g2cResetV\">Reset view<\/button>\n  <\/div>\n<\/div>\n\n<div class=\"g2c-info\">\n  <h3 id=\"g2cInfoTitle\"><\/h3>\n  <p id=\"g2cInfoText\"><\/p>\n  <div class=\"g2c-facts\" id=\"g2cFacts\"><\/div>\n  <div class=\"g2c-key\">\n    <span><i style=\"background:rgba(56,150,138,0.45); border:1px solid rgba(28,60,56,0.5)\"><\/i>Group 2 cation, M<sup>2+<\/sup><\/span>\n    <span><i style=\"background:#484e5c\"><\/i>Carbon<\/span>\n    <span><i style=\"background:#3462c8\"><\/i>Nitrogen<\/span>\n    <span><i style=\"background:#cd342c\"><\/i>Oxygen<\/span>\n    <span><i style=\"background:rgba(46,96,210,0.35); border:1.5px dotted rgba(46,96,210,0.9)\"><\/i>Electron density<\/span>\n    <span><i style=\"background:#8c92a0\"><\/i>Bond<\/span>\n    <span><i style=\"background:#e83c34\"><\/i>Bond breaking<\/span>\n    <span><i style=\"background:rgba(150,78,28,0.6)\"><\/i>NO<sub>2<\/sub>, brown gas<\/span>\n    <span><i style=\"background:#1C244B\"><\/i>Ionic radius ruler<\/span>\n  <\/div>\n<\/div>\n<\/section>\n\n<p class=\"ols-cc-g2c-001\">&copy; Dr. Mohammed Al-Fatah &#8211; <a href=\"https:\/\/www.onlinelearningsystem.net\" target=\"_blank\" rel=\"noopener\">onlinelearningsystem.net<\/a><\/p>\n<script src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/JS\/group2-thermal-stability.js?v=20261003e\"><\/script>\n\n<div class=\"ols-key-box\">\n<p><strong>Exam sentence:<\/strong> Magnesium carbonate decomposes at a lower temperature than barium carbonate because the Mg\u00b2\u207a ion is smaller, so it has a higher charge density and polarises the carbonate ion more, weakening the C\u2013O bonds.<\/p>\n<\/div>\n<\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Check: Explaining Stability<\/h2>\n<p>Choose the correct polarisation argument and rank compounds by stability using ionic radius and charge.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"876\"><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">4<\/div>\n<h2>Showing the Trend Experimentally<\/h2>\n<\/div>\n<p>To compare the thermal stability of carbonates, heat the same amount in moles of each carbonate with the same Bunsen flame and pass the gas through limewater.<\/p><p>The <strong>time taken for the limewater to turn cloudy<\/strong> is a measure of how easily the carbonate decomposes: the longer the time, the more stable the carbonate.<\/p><p>For the nitrates, time how long the brown fumes take to appear, or test for oxygen with a glowing splint.<\/p>\n<p>The comparison is only fair if the amount of solid, the flame and the apparatus are the same each time, and the test is repeated to check the ranking.<\/p>\n<div class=\"ols-key-box\">\n<p><strong>Technique point:<\/strong> Use the same number of moles, not the same mass, because the compounds have different molar masses and the amount of gas that can form depends on the moles of anion.<\/p>\n<\/div>\n<\/article>\n<article class=\"ols-note-card soft\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">5<\/div>\n<h2>Flame Colours<\/h2>\n<\/div>\n<p>Compounds of the s-block metals give <strong>characteristic colours<\/strong> in a Bunsen flame. A nichrome wire is cleaned in concentrated hydrochloric acid, dipped in the solid or solution, and held in a hot blue flame.<\/p>\n<div class=\"ols-table-wrap\">\n<table class=\"ols-table\">\n<thead>\n<tr><th>Metal<\/th><th>Flame colour<\/th><th>Metal<\/th><th>Flame colour<\/th><\/tr>\n<\/thead>\n<tbody>\n<tr><td><strong>Lithium<\/strong><\/td><td>red<\/td><td>Magnesium<\/td><td>no colour (burns with a bright white light)<\/td><\/tr>\n<tr><td><strong>Sodium<\/strong><\/td><td>yellow<\/td><td>Calcium<\/td><td>brick red<\/td><\/tr>\n<tr><td><strong>Potassium<\/strong><\/td><td>lilac<\/td><td>Strontium<\/td><td>red<\/td><\/tr>\n<tr><td><strong>Rubidium<\/strong><\/td><td>red<\/td><td>Barium<\/td><td>apple green<\/td><\/tr>\n<tr><td><strong>Caesium<\/strong><\/td><td>blue<\/td><td><\/td><td><\/td><\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>The colour comes from <strong>electron transitions<\/strong>. The heat of the flame promotes electrons in the metal ions to higher energy levels. When they fall back to lower levels they release the energy difference as light.<\/p>\n<p>The energy gaps are fixed for each element and correspond to particular frequencies in the visible region, so each element gives its own colour.<\/p>\n<p>Magnesium ions have no transition in the visible region, so magnesium compounds give no flame colour.<\/p>\n<div class=\"ols-figure-card ols-zoom-pop\">\n<div class=\"ols-figure-image\">\n<a class=\"ols-image-fullscreen-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/redox-groups-flame-colours.png\" target=\"_blank\" rel=\"noopener\" aria-label=\"Open image fullscreen\">\n<img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/redox-groups-flame-colours.png\" alt=\"Flame colours of Group 1 and 2 ions and the electron transitions that cause them\" data-fullscreen-src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/redox-groups-flame-colours.png\">\n<\/a>\n<\/div>\n<div class=\"ols-figure-caption\"><p>Each flame colour is a fingerprint of the energy gaps in that element: the electron is promoted by the heat and emits light of a fixed frequency as it falls back.<\/p><\/div>\n<\/div>\n<div class=\"ols-key-box\">\n<p><strong>Exam wording:<\/strong> &#8220;Electrons are excited to higher energy levels by the heat; as they fall back to lower levels they emit light of a specific frequency, which corresponds to a colour in the visible region.&#8221;<\/p>\n<\/div>\n<\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Check: Flame Colours and Their Cause<\/h2>\n<p>Identify metals from flame colours and choose the correct explanation of why the light is emitted.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"877\"><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card\">\n<div class=\"ols-note-title\">\n<div class=\"ols-note-icon\">6<\/div>\n<h2>Common Exam Points<\/h2>\n<\/div>\n<h3>Explain why the thermal stability of carbonates increases down Group 2<\/h3><p>The cation gets larger, its charge density falls, it polarises the carbonate ion less, so the C\u2013O bonds are less weakened and more energy is needed to break them.<\/p>\n<h3>Write the equation for the decomposition of a Group 2 nitrate<\/h3><p>2M(NO\u2083)\u2082 \u2192 2MO + 4NO\u2082 + O\u2082.<\/p>\n<h3>Explain the origin of a flame colour<\/h3><p>Electrons promoted by heat fall back to lower energy levels and emit light of a frequency fixed by the energy gap.<\/p>\n<h3>Do not say<\/h3><p>&#8220;Barium carbonate has stronger ionic bonds so it is more stable&#8221;; &#8220;sodium nitrate gives brown fumes&#8221;; &#8220;the flame colour comes from the anion&#8221;.<\/p>\n<\/article>\n<section class=\"ols-faq-card\">\n<h2>FAQs<\/h2>\n<p>Use these quick answers to check thermal stability and flame colours.<\/p>\n\n<div class=\"ols-faq-list\">\n<div class=\"ols-faq-item\">\n<h3>Why does thermal stability increase down the group?<\/h3>\n<p>The cation gets larger, so its charge density falls and it polarises the carbonate or nitrate ion less, leaving the C\u2013O or N\u2013O bonds stronger.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>Why are Group 1 carbonates more stable than Group 2 carbonates?<\/h3>\n<p>A 1+ ion has a lower charge density than a 2+ ion of similar size, so it polarises the anion less.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>What are the products when a Group 2 nitrate decomposes?<\/h3>\n<p>The metal oxide, nitrogen dioxide (brown gas) and oxygen: 2M(NO\u2083)\u2082 \u2192 2MO + 4NO\u2082 + O\u2082.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>How is a flame colour produced?<\/h3>\n<p>Heat promotes electrons to higher energy levels; as they fall back they emit light of a fixed frequency, which is a colour in the visible region.<\/p>\n<\/div>\n\n<div class=\"ols-faq-item\">\n<h3>Why does magnesium give no flame colour?<\/h3>\n<p>The energy gaps in magnesium ions do not correspond to visible light, so no colour is seen, although burning magnesium gives a bright white light.<\/p>\n<\/div>\n<\/div>\n<\/section>\n<section class=\"ols-related-card\">\n<h2>Related Topic 8B Groups 1 and 2 Pages<\/h2>\n<p>Use these pages to connect the ideas across groups 1 and 2 and the rest of Topic 8.<\/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-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/trends-down-groups-1-and-2\/\">Trends Down Groups 1 and 2<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/reactions-of-the-group-1-and-2-elements\/\">Reactions of the Group 1 and 2 Elements<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/oxides-hydroxides-and-carbonates\/\">Oxides, Hydroxides and Carbonates<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/solubility-trends-and-the-sulfate-test\/\">Solubility Trends and the Sulfate Test<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/tests-for-ions\/\">Tests for Ions<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/titrations-and-measurement-uncertainty\/\">Titrations and Measurement Uncertainty<\/a>\n<a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/\">Topic 8B Groups 1 and 2 Overview<\/a>\n<\/div>\n<\/section>\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    <\/main>\n  \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-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/#webpage\",\n      \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/\",\n      \"name\": \"Thermal Stability and Flame Colours | Topic 8B Groups 1 and 2 | Online Learning System\",\n      \"description\": \"Edexcel International A Level Chemistry revision notes on thermal stability of Group 1 and 2 nitrates and carbonates, polarisation by the cation, the experiments, and flame colours explained by electron transitions.\",\n      \"isPartOf\": {\n        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/#website\"\n      },\n      \"breadcrumb\": {\n        \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/#breadcrumb\"\n      }\n    },\n    {\n      \"@type\": \"WebSite\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/#website\",\n      \"url\": \"https:\/\/www.onlinelearningsystem.net\/\",\n      \"name\": \"Online Learning System\"\n    },\n    {\n      \"@type\": \"BreadcrumbList\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/#breadcrumb\",\n      \"itemListElement\": [\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 1,\n          \"item\": {\n            \"@type\": \"WebPage\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\",\n            \"name\": \"Revision Notes\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 2,\n          \"item\": {\n            \"@type\": \"WebPage\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\",\n            \"name\": \"A Level Chemistry\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 3,\n          \"item\": {\n            \"@type\": \"WebPage\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/\",\n            \"name\": \"Edexcel International\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 4,\n          \"item\": {\n            \"@type\": \"WebPage\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/\",\n            \"name\": \"Topic 8 Redox Chemistry and Groups 1, 2 and 7\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 5,\n          \"item\": {\n            \"@type\": \"WebPage\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/\",\n            \"name\": \"Topic 8B Groups 1 and 2\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 6,\n          \"item\": {\n            \"@type\": \"WebPage\",\n            \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/\",\n            \"name\": \"Thermal Stability and Flame Colours\"\n          }\n        }\n      ]\n    },\n    {\n      \"@type\": \"Course\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/#course\",\n      \"name\": \"Thermal Stability and Flame Colours\",\n      \"description\": \"Edexcel International A Level Chemistry revision notes on thermal stability of Group 1 and 2 nitrates and carbonates, polarisation by the cation, the experiments, and flame colours explained by electron transitions.\",\n      \"provider\": {\n        \"@type\": \"Organization\",\n        \"name\": \"Online Learning System\",\n        \"url\": \"https:\/\/www.onlinelearningsystem.net\/\"\n      },\n      \"educationalLevel\": \"A Level\",\n      \"about\": [\n        \"Redox\",\n        \"Oxidation number\",\n        \"Group 2\",\n        \"Group 1\",\n        \"Group 7\",\n        \"Halogens\",\n        \"Inorganic chemistry\"\n      ],\n      \"hasCourseInstance\": {\n        \"@type\": \"CourseInstance\",\n        \"courseMode\": \"Online\"\n      }\n    },\n    {\n      \"@type\": \"ItemList\",\n      \"@id\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/thermal-stability-and-flame-colours\/#relatedtopics\",\n      \"name\": \"Related Topic 8B Groups 1 and 2 Pages\",\n      \"itemListElement\": [\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 1,\n          \"item\": {\n            \"@type\": \"Course\",\n            \"name\": \"Trends Down Groups 1 and 2\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/trends-down-groups-1-and-2\/\",\n            \"description\": \"Edexcel International A Level Chemistry revision notes on the trends down Group 2 and Group 1: atomic radius, ionisation energies, melting points and the increase in reactivity down the group.\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 2,\n          \"item\": {\n            \"@type\": \"Course\",\n            \"name\": \"Reactions of the Group 1 and 2 Elements\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/reactions-of-the-group-1-and-2-elements\/\",\n            \"description\": \"Edexcel International A Level Chemistry revision notes on the reactions of the Group 2 and Group 1 elements with oxygen, chlorine, water, steam and dilute acids, with equations, observations and redox analysis.\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 3,\n          \"item\": {\n            \"@type\": \"Course\",\n            \"name\": \"Oxides, Hydroxides and Carbonates\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/oxides-hydroxides-and-carbonates\/\",\n            \"description\": \"Edexcel International A Level Chemistry revision notes on Group 2 oxides, hydroxides and carbonates: reactions with water and acids, pH trend, and uses of Ca(OH)\u2082, Mg(OH)\u2082 and CaCO\u2083.\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 4,\n          \"item\": {\n            \"@type\": \"Course\",\n            \"name\": \"Solubility Trends and the Sulfate Test\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/solubility-trends-and-the-sulfate-test\/\",\n            \"description\": \"Edexcel International A Level Chemistry revision notes on Group 2 solubility trends: hydroxides and sulfates, Mg(OH)\u2082 and BaSO\u2084, the acidified barium chloride test for sulfate ions and barium meals.\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 5,\n          \"item\": {\n            \"@type\": \"Course\",\n            \"name\": \"Tests for Ions\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/tests-for-ions\/\",\n            \"description\": \"Edexcel International A Level Chemistry revision notes on tests for carbonate, hydrogencarbonate, sulfate, halide and ammonium ions, with ionic equations and the order of tests on an unknown.\"\n          }\n        },\n        {\n          \"@type\": \"ListItem\",\n          \"position\": 6,\n          \"item\": {\n            \"@type\": \"Course\",\n            \"name\": \"Titrations and Measurement Uncertainty\",\n            \"url\": \"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8-redox-chemistry-and-groups-1-2-and-7\/8b-groups-1-and-2\/titrations-and-measurement-uncertainty\/\",\n            \"description\": \"Edexcel International A Level Chemistry revision notes on titration calculations, concordant titres, concentrations in mol dm\u207b\u00b3 and g dm\u207b\u00b3, and estimating and minimising measurement uncertainty.\"\n          }\n        }\n      ]\n    }\n  ]\n}\n<\/script>\n\n<\/section>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Revision Notes \/ A Level Chemistry \/ Edexcel International \/ Topic 8 Redox Chemistry and Groups 1, 2 and 7 \/ Topic 8B Groups 1 and 2 \/ Thermal Stability and Flame Colours Thermal Stability and Flame Colours A concise revision guide to the thermal decomposition of the Group 1 and 2 nitrates and carbonates, [&hellip;]<\/p>\n","protected":false},"author":12,"featured_media":0,"parent":10471,"menu_order":8,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-10481","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/10481","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=10481"}],"version-history":[{"count":2,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/10481\/revisions"}],"predecessor-version":[{"id":14149,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/10481\/revisions\/14149"}],"up":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/10471"}],"wp:attachment":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/media?parent=10481"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}