{"id":3436,"date":"2026-05-13T07:35:50","date_gmt":"2026-05-13T06:35:50","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/?page_id=3436"},"modified":"2026-06-28T05:54:57","modified_gmt":"2026-06-28T04:54:57","slug":"bromine-water","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/reactions-of-alkenes\/bromine-water\/","title":{"rendered":"Bromine Water"},"content":{"rendered":"\n<section class=\"ols-revision-page ols-alkene-bromine-water-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      --green: #3f8f46;\n      --red: #d94b2b;\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, 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<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 5 Alkenes<\/h4>\r\n\r\n    <ul class=\"ols-topic-list\">\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/alkene-bonding\/\">Alkene Bonding<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/geometric-isomerism\/\">Geometric Isomerism<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/electrophilic-addition-mechanism\/\">Electrophilic Addition Mechanism<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/reactions-of-alkenes\/\">Reactions of Alkenes<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/reactions-of-alkenes\/halogens\/\">Halogens<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/reactions-of-alkenes\/hydrogen-halide\/\">Hydrogen Halide<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/reactions-of-alkenes\/bromine-water\/\">Bromine Water<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/reactions-of-alkenes\/hydrogen\/\">Hydrogen<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/reactions-of-alkenes\/steam\/\">Steam<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/reactions-of-alkenes\/kmno4\/\">KMnO4<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/polymerisation-reactions\/\">Polymerisation Reactions<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-5-alkenes\/polymer-waste\/\">Polymer Waste<\/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-international\/topic-6-energetics\/\">Energetics<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-7-intermolecular-forces\/\">Intermolecular Forces<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel-international\/topic-8A-redox-chemistry\/\">Redox Chemistry<\/a>\r\n      <\/li>\r\n    <\/ul>\r\n  <\/div>\r\n<\/aside>\r\n\r\n<script>\r\n(function() 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 <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-5-alkenes\/\">Topic 5 Alkenes<\/a> \/\n        <span>Reactions of Alkenes: Bromine Water<\/span>\n      <\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Reactions of Alkenes with Bromine Water<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to the reaction of alkenes with bromine water, including the orange to colourless observation, why the reaction is a test for the alkene functional group and how the C=C double bond reacts by addition.<\/p>\n\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Exam board: Edexcel International<\/div>\n          <div class=\"ols-badge\">Topic 5: Alkenes<\/div>\n          <div class=\"ols-badge\">Reaction 3: Bromine Water<\/div>\n        <\/div>\n\n        <div class=\"ols-author\">\n\n    <img decoding=\"async\"\n      class=\"ols-author-avatar-img\"\n      src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Author-Profile.jpeg\"\n      alt=\"Dr. Mohammed Al-Fatah\"\n    >\n\n    <div class=\"ols-author-content\">\n\n      <h2 class=\"ols-author-title\">\n        Written by: Dr. Mohammed Al-Fatah\n      <\/h2>\n\n      <p class=\"ols-author-description\">\n        Chemistry specialist revision notes for A Level Chemistry.\n      <\/p>\n\n      <a class=\"ols-linkedin-pill\" href=\"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\" target=\"_blank\" rel=\"noopener noreferrer\">\n        <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 soft\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">1<\/div>\n          <h2>The Overall Reaction<\/h2>\n        <\/div>\n\n        <p>Alkenes react with <strong>bromine water<\/strong> in an <strong>addition reaction<\/strong>. Bromine water is bromine dissolved in water, and the reaction takes place at <strong>room temperature<\/strong>.<\/p>\n        <p>The C=C double bond opens and atoms add across the double bond. This means the alkene becomes a saturated organic product.<\/p>\n        <p>The key observation is that the <strong>orange colour of bromine water decolourises to colourless<\/strong>.<\/p>\n\n        <div class=\"ols-reaction-summary\">\n          <div class=\"ols-summary-item\"><span>Reagent<\/span><strong>Bromine dissolved in water<\/strong><\/div>\n          <div class=\"ols-summary-item\"><span>Conditions<\/span><strong>Room temperature<\/strong><\/div>\n          <div class=\"ols-summary-item\"><span>Type of reaction<\/span><strong>Addition<\/strong><\/div>\n          <div class=\"ols-summary-item\"><span>Observation<\/span><strong>Orange \u2192 colourless<\/strong><\/div>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Key idea:<\/strong> The colour change happens because bromine reacts with the C=C double bond, so bromine water is used as a chemical test for alkenes.<\/p>\n        <\/div>\n\n        <div class=\"ols-figure-card\">\n          <div class=\"ols-figure-image\">\n            <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Chemical-reaction-mechanism-illustration.webp\" alt=\"Reaction of an alkene with bromine water\">\n          <\/div>\n          <div class=\"ols-figure-caption\">\n            <p>The C=C double bond reacts with bromine water, causing the orange colour to disappear.<\/p>\n          <\/div>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">2<\/div>\n          <h2>Using Bromine Water to Test for Alkenes<\/h2>\n        <\/div>\n\n        <p>Bromine water is commonly used to test whether an organic compound contains an <strong>alkene functional group<\/strong>.<\/p>\n        <p>If a C=C double bond is present, bromine water changes from <strong>orange to colourless<\/strong>. This positive test shows that the bromine has reacted with the alkene.<\/p>\n        <p>If there is no C=C double bond under these conditions, the orange colour is expected to remain.<\/p>\n\n        <div class=\"ols-test-grid\">\n          <div class=\"ols-test-card\">\n            <h3>Positive test<\/h3>\n            <p>Bromine water decolourises from orange to colourless. This suggests the compound contains a C=C double bond.<\/p>\n          <\/div>\n\n          <div class=\"ols-test-card\">\n            <h3>Negative test<\/h3>\n            <p>The orange colour remains. This suggests there is no alkene functional group reacting under the test conditions.<\/p>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Exam focus:<\/strong> State both the reagent and the observation: bromine water changes from orange to colourless.<\/p>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">3<\/div>\n          <h2>Why This Is an Addition Reaction<\/h2>\n        <\/div>\n\n        <p>Alkenes are unsaturated because they contain a <strong>carbon-carbon double bond, C=C<\/strong>. The double bond contains an electron-rich \u03c0 bond, which is the reactive part of the molecule.<\/p>\n        <p>During addition, the \u03c0 bond is broken and new bonds form to the two carbon atoms from the original double bond.<\/p>\n        <p>The overall result is that the molecule becomes more saturated because atoms have been added across the C=C bond.<\/p>\n\n        <div class=\"ols-definition-box\">\n          <div class=\"ols-definition-circle\">C=C<\/div>\n          <p><strong>Addition reaction:<\/strong> A reaction in which atoms are added across a double bond, converting an unsaturated molecule into a more saturated product.<\/p>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Remember:<\/strong> In alkene addition reactions, the C=C double bond is the reactive site. The \u03c0 bond reacts first because it is electron-rich and more exposed than the \u03c3 bond.<\/p>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">4<\/div>\n          <h2>The Reaction Mechanism<\/h2>\n        <\/div>\n\n        <p>The reaction of an alkene with bromine water is linked to the same core idea as other alkene addition reactions: the electron-rich \u03c0 bond reacts first.<\/p>\n        <p>The C=C double bond provides electron density, allowing the reaction to begin. The double bond then opens and new bonds form across the two carbon atoms.<\/p>\n        <p>This explains why the characteristic orange colour disappears. Bromine is consumed as it reacts with the alkene.<\/p>\n\n        <div class=\"ols-mechanism-steps\">\n          <div class=\"ols-step-card\">\n            <h3>Step 1: The C=C bond reacts<\/h3>\n            <p>The \u03c0 bond in the alkene is electron-rich and begins the reaction with bromine water.<\/p>\n          <\/div>\n\n          <div class=\"ols-step-card\">\n            <h3>Step 2: The double bond opens<\/h3>\n            <p>The alkene loses the C=C double bond as atoms add across the two carbon atoms.<\/p>\n          <\/div>\n\n          <div class=\"ols-step-card\">\n            <h3>Step 3: The colour change is observed<\/h3>\n            <p>The orange colour of bromine water decolourises to colourless as bromine is used up in the reaction.<\/p>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-figure-card\">\n          <div class=\"ols-figure-image\">\n            <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/bromine-water-mechanism.webp\" alt=\"Bromine water reaction mechanism with an alkene\">\n          <\/div>\n          <div class=\"ols-figure-caption\">\n            <p>The mechanism shows how the alkene double bond reacts and why bromine water loses its orange colour.<\/p>\n          <\/div>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">5<\/div>\n          <h2>Common Exam Mistakes<\/h2>\n        <\/div>\n\n        <p>Students often lose marks by saying only that bromine water \u201cgoes clear\u201d without giving the full starting colour. The full observation is <strong>orange to colourless<\/strong>.<\/p>\n        <p>Another common error is to describe the reaction as substitution. This is incorrect for alkenes. The reaction is <strong>addition<\/strong> because atoms are added across the C=C double bond.<\/p>\n        <p>For a test question, the safest answer should include the reagent, condition and observation.<\/p>\n\n        <div class=\"ols-reaction-summary\">\n          <div class=\"ols-summary-item\"><span>Do say<\/span><strong>Bromine water decolourises from orange to colourless.<\/strong><\/div>\n          <div class=\"ols-summary-item\"><span>Do not just say<\/span><strong>It goes clear.<\/strong><\/div>\n          <div class=\"ols-summary-item\"><span>Reaction type<\/span><strong>Addition, not substitution.<\/strong><\/div>\n          <div class=\"ols-summary-item\"><span>Reason<\/span><strong>The C=C double bond opens.<\/strong><\/div>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Exam focus:<\/strong> Link the observation to the alkene functional group. The colour change is evidence that a C=C double bond has reacted.<\/p>\n        <\/div>\n      <\/article>\n\n      <section class=\"ols-h5p-card\">\n        <h2>Check Your Understanding<\/h2>\n        <p>Use these short activities to check the key ideas before moving on to the next alkene reaction.<\/p>\n\n        <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-34\" class=\"h5p-iframe\" data-content-id=\"34\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T5.4.3.1 Drag: Bromine Water Key Concepts\"><\/iframe><\/div><\/div>\n        <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-35\" class=\"h5p-iframe\" data-content-id=\"35\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T5.4.3.2 MCQ: Bromine Water Test Observation\"><\/iframe><\/div><\/div>\n        <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-36\" class=\"h5p-iframe\" data-content-id=\"36\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T5.4.3.3 MCQ: Reaction Type with Bromine Water\"><\/iframe><\/div><\/div>\n        <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-37\" class=\"h5p-iframe\" data-content-id=\"37\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T5.4.3.4 MCQ: Why Bromine Water Tests for Alkenes\"><\/iframe><\/div><\/div>\n      <\/section>\n\n<section class=\"ols-course-cta-alkenes\" id=\"olsCourseCtaAlkenes001\">\n  <style>\n    .ols-course-cta-alkenes,\n    .ols-course-cta-alkenes * {\n      box-sizing: border-box;\n    }\n\n    .ols-course-cta-alkenes {\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 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transition:\n        transform 0.2s ease,\n        background 0.2s ease,\n        box-shadow 0.2s ease;\n    }\n\n    .ols-course-cta-alkenes .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-alkenes .ols-animation-pause-button.is-visible {\n      display: inline-flex;\n    }\n\n    @keyframes olsAnimationPlayPulse001 {\n      0% {\n        box-shadow:\n          0 18px 40px rgba(28, 36, 75, 0.30),\n          0 0 0 0 rgba(255, 255, 255, 0.40);\n      }\n\n      70% {\n        box-shadow:\n          0 18px 40px rgba(28, 36, 75, 0.30),\n          0 0 0 18px rgba(255, 255, 255, 0);\n      }\n\n      100% {\n        box-shadow:\n          0 18px 40px rgba(28, 36, 75, 0.30),\n          0 0 0 0 rgba(255, 255, 255, 0);\n      }\n    }\n\n    .ols-course-cta-alkenes .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-alkenes .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-alkenes .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-alkenes .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-alkenes .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-alkenes .ols-course-cta-top {\n        grid-template-columns: 1fr;\n      }\n\n      .ols-course-cta-alkenes .ols-course-cta-image-link {\n        max-width: 520px;\n        margin: 0 auto;\n      }\n\n      .ols-course-cta-alkenes .ols-course-cta-intro-stats {\n        grid-template-columns: 1fr;\n      }\n\n      .ols-course-cta-alkenes .ols-animation-frame-shell {\n        height: 520px;\n      }\n    }\n\n    @media (max-width: 760px) {\n      .ols-course-cta-alkenes {\n        margin: 26px 0 22px;\n      }\n\n      .ols-course-cta-alkenes .ols-course-cta-card {\n        padding: 20px;\n        border-radius: 24px;\n      }\n\n      .ols-course-cta-alkenes .ols-course-cta-header-row {\n        align-items: stretch;\n      }\n\n      .ols-course-cta-alkenes .ols-course-button-top {\n        width: 100%;\n      }\n\n      .ols-course-cta-alkenes .ols-course-cta-stats,\n      .ols-course-cta-alkenes .ols-course-cta-features {\n        grid-template-columns: 1fr;\n      }\n\n      .ols-course-cta-alkenes .ols-course-animation-wrap {\n        padding: 0;\n        border-radius: 0;\n      }\n\n      .ols-course-cta-alkenes .ols-animation-frame-shell {\n        height: 420px;\n        border-radius: 18px;\n      }\n\n      .ols-course-cta-alkenes .ols-animation-play-circle {\n        width: 76px;\n        height: 76px;\n      }\n\n      .ols-course-cta-alkenes .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-alkenes .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-alkenes .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\/alkenes-topic-5-edexcel-international\/\" aria-label=\"Open the Edexcel International A Level Chemistry Topic 5 Alkenes course page\">\n\n        <div class=\"ols-course-cta-image\">\n          <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/04\/edexcel-international-a-level-chemistry-topic-5-alkenes-interactive-course-banner.jpg\" alt=\"Edexcel International A Level Chemistry Topic 5 Alkenes interactive 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 5 Alkenes Course\n          <\/div>\n\n          <a class=\"ols-course-button ols-course-button-top\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/alkenes-topic-5-edexcel-international\/\">\n            View Course\n          <\/a>\n\n        <\/div>\n\n        <h2>\n          Master Alkenes for Edexcel International A Level Chemistry\n        <\/h2>\n\n      <\/div>\n\n    <\/div>\n\n    <div class=\"ols-course-cta-intro-stats\">\n\n      <p class=\"ols-course-cta-intro\">\n        Continue from these free revision notes into the full Topic 5 Alkenes 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>12 hours<\/strong>\n        <\/div>\n\n        <div class=\"ols-course-stat\">\n          <span>Video lessons<\/span>\n          <strong>145 mins<\/strong>\n        <\/div>\n\n        <div class=\"ols-course-stat\">\n          <span>MCQ practice<\/span>\n          <strong>41 marks<\/strong>\n        <\/div>\n\n        <div class=\"ols-course-stat\">\n          <span>SAQ practice<\/span>\n          <strong>244 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 the chemistry and exam technique 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 the full Topic 5 specification 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=\"olsCourseAnimationFrame001\" title=\"OLS course preview animation\" loading=\"lazy\" referrerpolicy=\"no-referrer\">\n        <\/iframe>\n\n        <button class=\"ols-animation-start-overlay\" id=\"olsCourseAnimationStart001\" 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=\"olsCourseAnimationPause001\" 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\/alkenes-topic-5-edexcel-international\/\">\n        View Alkenes Topic 5 Course\n      <\/a>\n\n    <\/div>\n\n  <\/div>\n\n  <template id=\"olsCourseAnimationTemplate001\">\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*{box-sizing:border-box;}\n\nhtml.ols-animation-paused *,\nhtml.ols-animation-paused *::before,\nhtml.ols-animation-paused *::after{\n  animation-play-state:paused!important;\n}\n\n:root{\n  --ols-video-screen-w:1180;\n  --ols-video-screen-h:664;\n  --ols-video-screen-scale:1;\n  --ols-mcq-screen-w:1360;\n  --ols-mcq-screen-h:1130;\n  --ols-mcq-screen-scale:1;\n  --ols-saq-screen-w:1360;\n  --ols-saq-screen-h:965;\n  --ols-saq-screen-scale:1;\n}\n\nhtml,\nbody{\n  width:100%;\n  height:100%;\n}\n\nbody{\n  margin:0;\n  overflow:hidden;\n  font-family:Poppins,Arial,sans-serif;\n  background:#e9efff;\n}\n\n.ols-combined-stage{\n  position:relative;\n  width:100vw;\n  height:100vh;\n  overflow:hidden;\n  background:\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\n}\n\n.ols-scene{\n  position:absolute;\n  inset:0;\n  width:100vw;\n  height:100vh;\n  opacity:0;\n  visibility:hidden;\n  pointer-events:none;\n}\n\n.ols-scene.active{\n  opacity:1;\n  visibility:visible;\n  pointer-events:auto;\n}\n\n.ols-scene.fade-out{\n  animation:olsSceneFadeOut 0.85s ease forwards;\n}\n\n@keyframes olsSceneFadeOut{\n  to{\n    opacity:0;\n    visibility:hidden;\n  }\n}\n\n.ols-title-cursor{\n  display:inline-block;\n  width:5px;\n  height:0.85em;\n  background:#1C244B;\n  margin-left:8px;\n  transform:translateY(8px);\n  animation:olsBlink 0.8s infinite;\n}\n\n.cursor{\n  display:inline-block;\n  width:3px;\n  height:28px;\n  background:#1c244b;\n  margin-left:3px;\n  transform:translateY(5px);\n  animation:olsBlink 0.8s infinite;\n}\n\n@keyframes olsBlink{\n  0%,45%{opacity:1;}\n  46%,100%{opacity:0;}\n}\n\n.ols-video-stage,\n.ols-mcq-stage,\n.ols-saq-stage{\n  width:100vw;\n  height:100vh;\n  display:flex;\n  justify-content:center;\n  align-items:center;\n  padding:0;\n  overflow:hidden;\n  background:\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\n}\n\n.ols-video-title-screen,\n.ols-mcq-intro-screen,\n.ols-saq-intro{\n  position:absolute;\n  inset:0;\n  z-index:50;\n  display:flex;\n  justify-content:center;\n  align-items:center;\n  background:\n    radial-gradient(circle at top left,rgba(70,127,247,0.14),transparent 34%),\n    linear-gradient(135deg,#f8fbff 0%,#e9efff 100%);\n  opacity:1;\n  visibility:visible;\n  pointer-events:none;\n}\n\n.ols-video-title-screen.hide{animation:olsVideoTitleFadeOut 0.85s ease forwards;}\n.ols-mcq-intro-screen.hide{animation:olsMcqIntroFadeOut 0.85s ease forwards;}\n.ols-saq-intro.hide{animation:olsSaqIntroFadeOut 0.85s ease forwards;}\n\n@keyframes olsVideoTitleFadeOut{to{opacity:0;visibility:hidden;}}\n@keyframes olsMcqIntroFadeOut{to{opacity:0;visibility:hidden;}}\n@keyframes olsSaqIntroFadeOut{to{opacity:0;visibility:hidden;}}\n\n.ols-video-title-wrap,\n.ols-mcq-intro-title-wrap,\n.ols-saq-intro-title-wrap{\n  max-width:1250px;\n  padding:0 34px;\n  text-align:center;\n}\n\n.ols-video-title,\n.ols-mcq-intro-title,\n.ols-saq-intro-title{\n  margin:0;\n  font-family:Poppins,Arial,sans-serif;\n  font-size:clamp(52px,8vw,124px);\n  font-weight:600;\n  line-height:1.08;\n  color:#1C244B;\n  text-shadow:-9px 0 9px rgba(28,36,75,0.16);\n  letter-spacing:-0.045em;\n}\n\n#videoTitleText,\n#mcqIntroTitleText,\n#saqIntroTitleText{\n  white-space:pre-wrap;\n}\n\n.ols-video-scene{\n  width:100%;\n  height:100%;\n  display:flex;\n  justify-content:center;\n  align-items:center;\n  opacity:0;\n  visibility:hidden;\n}\n\n.ols-video-scene.show{\n  visibility:visible;\n  animation:olsVideoSceneIn 1s ease forwards;\n}\n\n@keyframes olsVideoSceneIn{to{opacity:1;}}\n\n.ols-video-scale-wrap{\n  width:calc(var(--ols-video-screen-w) * 1px);\n  height:calc(var(--ols-video-screen-h) * 1px);\n  transform:scale(var(--ols-video-screen-scale));\n  transform-origin:center center;\n  display:flex;\n  justify-content:center;\n  align-items:center;\n}\n\n.ols-video-card{\n  width:1180px;\n  height:664px;\n  border-radius:28px;\n  overflow:hidden;\n  background:#1C244B;\n  box-shadow:0 28px 80px rgba(28,36,75,0.28);\n  transform:translateY(24px) scale(0.96);\n  opacity:0;\n}\n\n.ols-video-scene.show .ols-video-card{\n  animation:olsVideoCardIn 1s cubic-bezier(.18,.89,.32,1.12) forwards;\n  animation-delay:0.2s;\n}\n\n@keyframes olsVideoCardIn{\n  to{\n    transform:translateY(0) scale(1);\n    opacity:1;\n  }\n}\n\n.ols-video-card video{\n  display:block;\n  width:100%;\n  height:100%;\n  aspect-ratio:16 \/ 9;\n  object-fit:cover;\n  border:0;\n}\n\n.ols-mcq-scale-wrap,\n.ols-saq-scale-wrap{\n  width:calc(var(--ols-mcq-screen-w) * 1px);\n  height:calc(var(--ols-mcq-screen-h) * 1px);\n  transform:scale(var(--ols-mcq-screen-scale));\n  transform-origin:center center;\n  display:flex;\n  justify-content:center;\n  align-items:flex-start;\n}\n\n.ols-saq-scale-wrap{\n  width:calc(var(--ols-saq-screen-w) * 1px);\n  height:calc(var(--ols-saq-screen-h) * 1px);\n  transform:scale(var(--ols-saq-screen-scale));\n}\n\n.ols-mcq-screen{\n  width:1360px;\n  height:1130px;\n  border-radius:22px;\n  overflow:hidden;\n  background:#eaf0ff;\n  box-shadow:0 26px 70px rgba(28,36,75,0.22);\n  opacity:0;\n  transform:translateY(24px) scale(0.96);\n}\n\n.ols-mcq-screen.show{\n  animation:olsMcqScreenEnter 1s ease forwards;\n}\n\n@keyframes olsMcqScreenEnter{\n  from{opacity:0;transform:translateY(24px) scale(0.96);}\n  to{opacity:1;transform:translateY(0) scale(1);}\n}\n\n.mcq-question-area{\n  background:#eaf0ff;\n  padding:28px 30px 30px;\n  position:relative;\n  height:610px;\n}\n\n.mcq-question-lead{\n  margin:0 0 14px;\n  font-size:24px;\n  line-height:1.35;\n  color:#111827;\n}\n\n.mcq-ionic-table{\n  border-collapse:collapse;\n  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transition:opacity 0.25s ease,transform 0.25s ease;\n}\n\n.mcq-option-row.selected .mcq-radio::after{\n  opacity:1;\n  transform:scale(1);\n}\n\n.mcq-radio-ripple{\n  position:absolute;\n  left:14px;\n  top:50%;\n  width:28px;\n  height:28px;\n  border-radius:50%;\n  border:2px solid rgba(28,36,75,0.28);\n  transform:translate(-50%,-50%) scale(1);\n  opacity:0;\n  pointer-events:none;\n}\n\n.mcq-option-row.clicking .mcq-radio-ripple{\n  animation:mcqRipple 0.75s ease forwards;\n}\n\n@keyframes mcqRipple{\n  0%{opacity:0.65;transform:translate(-50%,-50%) scale(1);}\n  100%{opacity:0;transform:translate(-50%,-50%) scale(2.5);}\n}\n\n.mcq-option-label{\n  font-size:23px;\n  color:#111827;\n}\n\n.mcq-specific-feedback{\n  display:inline-flex;\n  align-items:center;\n  margin-left:18px;\n  min-height:38px;\n  opacity:0;\n  transform:translateX(-8px);\n}\n\n.mcq-specific-feedback.show{\n  opacity:1;\n  transform:translateX(0);\n  transition:opacity 0.35s ease,transform 0.35s ease;\n}\n\n.mcq-cross-icon{\n  width:26px;\n  height:26px;\n  border-radius:50%;\n  border:2px solid #d83255;\n  color:#d83255;\n  display:inline-flex;\n  justify-content:center;\n  align-items:center;\n  font-size:18px;\n  font-weight:700;\n  margin-right:12px;\n  opacity:0;\n  transform:scale(0.4);\n}\n\n.mcq-cross-icon.show{\n  animation:mcqCrossPop 0.35s ease forwards;\n}\n\n@keyframes mcqCrossPop{\n  70%{opacity:1;transform:scale(1.18);}\n  100%{opacity:1;transform:scale(1);}\n}\n\n.mcq-specific-feedback-text{\n  display:inline-block;\n  background:#fff4b8;\n  color:#111827;\n  padding:8px 16px;\n  font-size:22px;\n  line-height:1.35;\n  min-width:850px;\n  min-height:44px;\n}\n\n.mcq-submit-button{\n  position:absolute;\n  right:34px;\n  bottom:30px;\n  border:0;\n  border-radius:999px;\n  background:#1C244B;\n  color:#ffffff;\n  padding:14px 28px;\n  font-size:18px;\n  font-weight:600;\n  box-shadow:0 14px 32px rgba(28,36,75,0.25);\n  cursor:default;\n  transition:transform 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<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        <\/div>\n      <\/section>\n    <\/div>\n  <\/section>\n\n  <section id=\"sceneMcq\" class=\"ols-scene\">\n    <div class=\"ols-mcq-stage\">\n      <div id=\"mcqIntroScreen\" class=\"ols-mcq-intro-screen\">\n        <div class=\"ols-mcq-intro-title-wrap\">\n          <h1 class=\"ols-mcq-intro-title\">\n            <span id=\"mcqIntroTitleText\"><\/span><span id=\"mcqIntroTitleCursor\" class=\"ols-title-cursor\"><\/span>\n          <\/h1>\n        <\/div>\n      <\/div>\n\n      <div class=\"ols-mcq-scale-wrap\">\n        <main id=\"mcqScreen\" class=\"ols-mcq-screen\">\n          <section class=\"mcq-question-area\">\n            <p class=\"mcq-question-lead\">Some ionic radii are shown.<\/p>\n\n            <table class=\"mcq-ionic-table\">\n              <thead>\n                <tr>\n                  <th>Ion<\/th>\n                  <th>Ionic radius \/ nm<\/th>\n                <\/tr>\n              <\/thead>\n              <tbody>\n                <tr><td>Na<sup>+<\/sup><\/td><td>0.102<\/td><\/tr>\n                <tr><td>K<sup>+<\/sup><\/td><td>0.138<\/td><\/tr>\n                <tr><td>F<sup>\u2212<\/sup><\/td><td>0.133<\/td><\/tr>\n                <tr><td>Cl<sup>\u2212<\/sup><\/td><td>0.180<\/td><\/tr>\n              <\/tbody>\n            <\/table>\n\n            <p class=\"mcq-question-main\">Which compound has the strongest ionic bonding?<\/p>\n\n            <div class=\"mcq-options-wrap\">\n              <div id=\"mcqWrongOption\" class=\"mcq-option-row\">\n                <span class=\"mcq-radio\"><\/span>\n                <span class=\"mcq-radio-ripple\"><\/span>\n                <span class=\"mcq-option-label\">sodium chloride<\/span>\n\n                <span id=\"mcqSpecificFeedback\" class=\"mcq-specific-feedback\">\n                  <span id=\"mcqCrossIcon\" class=\"mcq-cross-icon\">\u00d7<\/span>\n                  <span class=\"mcq-specific-feedback-text\">\n                    <span id=\"mcqSpecificText\"><\/span><span id=\"mcqSpecificCursor\" class=\"cursor mcq-specific-cursor\" style=\"display:none;\"><\/span>\n                  <\/span>\n                <\/span>\n              <\/div>\n\n              <div class=\"mcq-option-row\"><span class=\"mcq-radio\"><\/span><span class=\"mcq-radio-ripple\"><\/span><span class=\"mcq-option-label\">potassium chloride<\/span><\/div>\n              <div class=\"mcq-option-row\"><span class=\"mcq-radio\"><\/span><span class=\"mcq-radio-ripple\"><\/span><span class=\"mcq-option-label\">sodium fluoride<\/span><\/div>\n              <div class=\"mcq-option-row\"><span class=\"mcq-radio\"><\/span><span class=\"mcq-radio-ripple\"><\/span><span class=\"mcq-option-label\">potassium fluoride<\/span><\/div>\n            <\/div>\n\n            <button 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class=\"saq-question-text\">\n              <strong>(ii)<\/strong>&nbsp;&nbsp; Melting temperature depends on the strength of metallic bonding.<br>\n              Explain why the metallic bonding in magnesium is much stronger than that in sodium.\n            <\/div>\n\n            <div class=\"saq-student-box\">\n              <span id=\"saqStudentText\"><\/span><span id=\"saqStudentCursor\" class=\"cursor\"><\/span>\n            <\/div>\n          <\/section>\n\n          <section id=\"saqTeacherFeedback\" class=\"saq-teacher-feedback\">\n            <span id=\"saqTeacherText\"><\/span><span id=\"saqTeacherCursor\" class=\"cursor saq-teacher-cursor\" style=\"display:none;\"><\/span>\n          <\/section>\n        <\/main>\n      <\/div>\n    <\/div>\n  <\/section>\n\n<\/div>\n\n<script>\n(function(){\n  const nativeSetTimeout=window.setTimeout.bind(window);\n  const nativeClearTimeout=window.clearTimeout.bind(window);\n  let nextTimerId=1;\n  let paused=false;\n  const timers=new 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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. 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