{"id":4523,"date":"2026-05-28T06:05:24","date_gmt":"2026-05-28T05:05:24","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/successive-ionisation-energies\/"},"modified":"2026-05-30T09:07:05","modified_gmt":"2026-05-30T08:07:05","slug":"successive-ionisation-energies","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/successive-ionisation-energies\/","title":{"rendered":"Successive Ionisation Energies"},"content":{"rendered":"\n<!--\n===============================================================================\nONLINE LEARNING SYSTEM COPYRIGHT NOTICE\n\u00a9 Online Learning System. 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<h3>Revision Notes<\/h3>\r\n    <p>A Level Chemistry<\/p>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Topic 1 Atomic Structure and The Periodic Table<\/h4>\r\n\r\n    <ul class=\"ols-topic-list\">\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/atomic-structure\/\">Atomic Structure<\/a>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/\">Mass Spectrometry<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/the-mass-spectrometer\/\">The Mass Spectrometer<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/ram-calculations\/\">RAM Calculations<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/predicting-diatomic-mass-spectra\/\">Predicting Diatomic Mass Spectra<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/mass-spectrometry\/identifying-compounds-from-mass-spectra\/\">Identifying Compounds from Mass Spectra<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/electron-configuration\/\">Electron Configuration<\/a>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/\">Ionisation Energy<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/introduction-to-ionisation-energy\/\">Introduction to Ionisation Energy<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/successive-ionisation-energies\/\">Successive Ionisation Energies<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-period\/\">Trends in a Period<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/trends-in-a-group\/\">Trends in a Group<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/periodic-trends\/\">Periodic Trends<\/a>\r\n      <\/li>\r\n    <\/ul>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Next Topics<\/h4>\r\n\r\n    <ul class=\"ols-topic-list\">\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/\">Bonding &amp; Structure<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-3-redox-i\/\">Redox I<\/a>\r\n      <\/li>\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-4-inorganic-chemistry-and-the-periodic-table\/\">Inorganic Chemistry &amp; The Periodic Table<\/a>\r\n      <\/li>\r\n    <\/ul>\r\n  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class=\"ols-breadcrumbs\" aria-label=\"Breadcrumb\">\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/\">Revision Notes<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/\">A Level Chemistry<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/\">Edexcel<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/\">Topic 1 Atomic Structure &amp; The Periodic Table<\/a> \/\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-1-atomic-structure-and-the-periodic-table\/ionisation-energy\/\">Ionisation Energy<\/a> \/\n        <span>Successive Ionisation Energies<\/span>\n      <\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Successive Ionisation Energies<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to successive ionisation energies, why each ionisation energy increases, and how large jumps reveal an element\u2019s group and electronic structure.<\/p>\n\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Unit: Paper 1<\/div>\n          <div class=\"ols-badge\">Topic 1: Atomic Structure &amp; The Periodic Table<\/div>\n          <div class=\"ols-badge\">9CH0\/01<\/div>\n        <\/div>\n\n        <div class=\"ols-author\">\n          <img decoding=\"async\" class=\"ols-author-avatar-img\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Author-Profile.jpeg\" alt=\"Dr. Mohammed Al-Fatah\">\n          <div class=\"ols-author-content\">\n            <h2 class=\"ols-author-title\">Written by:<br><span>Dr. Mohammed Al-Fatah<\/span><\/h2>\n            <p class=\"ols-author-description\">Chemistry specialist revision notes for A Level Chemistry.<\/p>\n            <a class=\"ols-linkedin-pill\" href=\"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\" target=\"_blank\" rel=\"noopener noreferrer\">\n              <svg class=\"ols-linkedin-icon\" viewBox=\"0 0 24 24\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M4.98 3.5C4.98 4.88 3.86 6 2.48 6S0 4.88 0 3.5 1.12 1 2.48 1s2.5 1.12 2.5 2.5zM.5 8h4V24h-4V8zm7 0h3.8v2.2h.1c.5-.9 1.8-2.2 3.9-2.2 4.2 0 5 2.8 5 6.4V24h-4v-7.6c0-1.8 0-4.2-2.6-4.2s-3 2-3 4v7.8h-4V8z\"><\/path><\/svg>\n              View LinkedIn Profile\n            <\/a>\n          <\/div>\n        <\/div>\n      <\/header>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">1<\/div><h2>What Are Successive Ionisation Energies?<\/h2><\/div>\n        <p><strong>Successive ionisation energies<\/strong> are the energies required to remove electrons one after another from the same element in the gaseous state.<\/p>\n        <p>The first ionisation energy removes one electron from a neutral gaseous atom. The second ionisation energy removes one electron from a gaseous 1+ ion. The third ionisation energy removes one electron from a gaseous 2+ ion, and so on.<\/p>\n\n        <div class=\"ols-definition-box\">\n          <p><strong>Core idea:<\/strong> successive ionisation energy data shows how strongly each electron is held as electrons are removed from the atom or ion one at a time.<\/p>\n        <\/div>\n      <\/article>\n\n      <div class=\"ols-zoom-card\">\n        <div class=\"ols-zoom-card-image\">\n          <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Ionisation-energy-infographic-explanation.webp\" alt=\"Successive ionisation energy explanation showing why ionisation energy increases and why large jumps occur\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>The large rises occur when removal moves from an outer shell into an inner shell that is closer to the nucleus.<\/p>\n        <\/div>\n      <\/div>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">2<\/div><h2>Why Each Ionisation Energy Increases<\/h2><\/div>\n        <p>Each ionisation energy is normally larger than the previous one because, after each electron is removed, the species becomes more positively charged.<\/p>\n        <p>The remaining electrons are attracted more strongly by the nucleus. There is also less electron-electron repulsion between the remaining electrons. This means it becomes harder to remove the next electron, so more energy is required each time.<\/p>\n\n        <div class=\"ols-rule-list\">\n          <div class=\"ols-rule-item\">\n            <h3>A positive ion forms<\/h3>\n            <p>Removing the first electron forms a positive ion, so the remaining electrons experience stronger attraction.<\/p>\n          <\/div>\n\n          <div class=\"ols-rule-item\">\n            <h3>Electron-electron repulsion decreases<\/h3>\n            <p>With fewer electrons left, there is less repulsion between electrons, so the remaining electrons are held more strongly.<\/p>\n          <\/div>\n\n          <div class=\"ols-rule-item\">\n            <h3>The next electron is harder to remove<\/h3>\n            <p>More energy is needed to overcome the stronger attraction between the nucleus and the next electron.<\/p>\n          <\/div>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">3<\/div><h2>Why Big Jumps Happen<\/h2><\/div>\n        <p>A <strong>big jump<\/strong> in successive ionisation energy shows that an electron is being removed from a shell closer to the nucleus.<\/p>\n        <p>Electrons in inner shells are closer to the nucleus and have less shielding from inner complete shells. They are therefore much more strongly attracted to the nucleus, so a much larger amount of energy is needed to remove them.<\/p>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Exam focus:<\/strong> A big jump means the previous electron was the last electron in the outer shell. The next electron comes from an inner shell.<\/p>\n        <\/div>\n      <\/article>\n\n      <div class=\"ols-zoom-card\">\n        <div class=\"ols-zoom-card-image\">\n          <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Ionisation-energy-and-electron-structure-explained.webp\" alt=\"Ionisation energy graph linked to electronic structure showing a large jump after four electrons are removed\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>The position of the jump is used to infer how many electrons were in the outer shell before ionisation reached the next shell.<\/p>\n        <\/div>\n      <\/div>\n\n      <article class=\"ols-note-card orange\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">4<\/div><h2>Using the First Big Jump to Find the Group<\/h2><\/div>\n        <p>The first large jump tells you how many electrons were removed before the atom started losing electrons from an inner shell.<\/p>\n        <p>For main-group elements, count how many electrons are removed before the first big jump. That number gives the group number for Group 1 to Group 7 elements. For example, if the first big jump is between the second and third ionisation energies, the element is in Group 2.<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Pattern in successive ionisation energy<\/th>\n                <th>Outer-shell electrons<\/th>\n                <th>Likely group<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Pattern in successive ionisation energy\">Big jump between 1st and 2nd ionisation energies<\/td>\n                <td data-label=\"Outer-shell electrons\">1 electron removed before the jump<\/td>\n                <td data-label=\"Likely group\">Group 1<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Pattern in successive ionisation energy\">Big jump between 2nd and 3rd ionisation energies<\/td>\n                <td data-label=\"Outer-shell electrons\">2 electrons removed before the jump<\/td>\n                <td data-label=\"Likely group\">Group 2<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Pattern in successive ionisation energy\">Big jump between 3rd and 4th ionisation energies<\/td>\n                <td data-label=\"Outer-shell electrons\">3 electrons removed before the jump<\/td>\n                <td data-label=\"Likely group\">Group 3<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Pattern in successive ionisation energy\">Big jump between 7th and 8th ionisation energies<\/td>\n                <td data-label=\"Outer-shell electrons\">7 electrons removed before the jump<\/td>\n                <td data-label=\"Likely group\">Group 7<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Method:<\/strong> count the number of ionisation energies before the first major jump. This tells you the number of outer-shell electrons.<\/p>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">5<\/div><h2>Using the Graph to Find Electronic Structure<\/h2><\/div>\n        <p>Successive ionisation energy graphs can also be used to work out the number of electrons in each shell.<\/p>\n        <p>Start from the right-hand side of the graph and work from right to left. Count how many points appear before each big jump. This gives the number of electrons in each shell, starting with the first shell closest to the nucleus.<\/p>\n      <\/article>\n\n      <div class=\"ols-zoom-card\">\n        <div class=\"ols-zoom-card-image\">\n          <img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/Ionisation-energy-trend-Graph-of-sodium.png\" alt=\"Successive ionisation energy trend of sodium showing large jumps between electron shells\" class=\"ols-zoomable-img ols-lightbox-target\" draggable=\"false\">\n        <\/div>\n        <div class=\"ols-zoom-card-caption\">\n          <p>For sodium, the graph shows 2 electrons in the first shell, 8 in the second shell and 1 in the third shell.<\/p>\n        <\/div>\n      <\/div>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">6<\/div><h2>Worked Pattern Example<\/h2><\/div>\n        <p>Suppose an element has the following successive ionisation energies:<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Ionisation number<\/th>\n                <th>1st<\/th>\n                <th>2nd<\/th>\n                <th>3rd<\/th>\n                <th>4th<\/th>\n                <th>5th<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Ionisation number\"><strong>Ionisation energy \/ kJ mol\u207b\u00b9<\/strong><\/td>\n                <td data-label=\"1st\">590<\/td>\n                <td data-label=\"2nd\">1150<\/td>\n                <td data-label=\"3rd\">4940<\/td>\n                <td data-label=\"4th\">6480<\/td>\n                <td data-label=\"5th\">8120<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <p>There is a large jump between the second and third ionisation energies. This means two electrons were removed before the first large jump, so the element has two electrons in its outer shell.<\/p>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Conclusion:<\/strong> the element is in Group 2 because the third electron is removed from an inner shell closer to the nucleus with less shielding.<\/p>\n        <\/div>\n      <\/article>\n\n      <article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\"><div class=\"ols-note-icon\">7<\/div><h2>Common Exam Points<\/h2><\/div>\n        <ul>\n          <li>Successive ionisation energies increase because each electron is removed from an increasingly positive species.<\/li>\n          <li>After an electron is removed, attraction between the nucleus and the remaining electrons increases.<\/li>\n          <li>Large jumps show that the next electron is being removed from a shell closer to the nucleus.<\/li>\n          <li>The number of electrons removed before the first big jump gives the number of outer-shell electrons.<\/li>\n          <li>The first large jump can be used to identify the group for main-group elements.<\/li>\n          <li>Always explain jumps using <strong>distance from the nucleus<\/strong>, <strong>shielding<\/strong> and <strong>nuclear attraction<\/strong>.<\/li>\n          <li>Do not simply say \u201cit is in a new shell\u201d. State that the electron is in a shell closer to the nucleus and is more strongly attracted.<\/li>\n        <\/ul>\n      <\/article>\n\n      <section class=\"ols-h5p-card\">\n        <h2>Check Your Understanding<\/h2>\n        <p>Use these short tasks to test the key ideas from this page before moving on to ionisation energy trends across periods and down groups.<\/p>\n\n        <div class=\"ols-h5p-grid\">\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-267\" class=\"h5p-iframe\" data-content-id=\"267\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T2.4.5 Drag: Successive Ionisation Energy Key Concepts\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-268\" class=\"h5p-iframe\" data-content-id=\"268\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T2.4.6 MCQ: Why Successive Ionisation Energies Increase\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-269\" class=\"h5p-iframe\" data-content-id=\"269\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T2.4.7 MCQ: Group Number from Successive Ionisation Energies\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-270\" class=\"h5p-iframe\" data-content-id=\"270\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"T2.4.8 MCQ: Electronic Structure from Successive Ionisation Energies\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-307\" class=\"h5p-iframe\" data-content-id=\"307\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Most stable chloride of element Z from ionisation energy data\"><\/iframe><\/div><\/div>\n          <div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-349\" class=\"h5p-iframe\" data-content-id=\"349\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Successive Ionisation Energy Dialog Cards\"><\/iframe><\/div><\/div>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-quicksnap-card\">\n        <h2>QuickSnap<\/h2>\n        <p>This text summary condenses the page into the essential exam ideas.<\/p>\n        <ul class=\"ols-quicksnap-list\">\n          <li><strong>Successive ionisation energies<\/strong> remove electrons one at a time from gaseous atoms or ions.<\/li>\n          <li><strong>Each value increases<\/strong> because the remaining electrons are attracted more strongly after a positive ion forms.<\/li>\n          <li><strong>A big jump<\/strong> means the next electron is being removed from an inner shell closer to the nucleus.<\/li>\n          <li><strong>Group number<\/strong> can be found by counting how many electrons are removed before the first big jump.<\/li>\n          <li><strong>Electronic structure<\/strong> can be inferred by counting groups of points between large jumps.<\/li>\n          <li><strong>Exam explanations<\/strong> should mention distance from the nucleus, shielding and nuclear attraction.<\/li>\n        <\/ul>\n      <\/section>\n\n\n<section class=\"ols-course-cta-atomic-structure\" id=\"olsCourseCtaAtomicStructure002\">\n        <style>\n          .ols-course-cta-atomic-structure,\n          .ols-course-cta-atomic-structure * {\n            box-sizing: border-box;\n          }\n      \n          .ols-course-cta-atomic-structure {\n            --navy: #1C244B;\n            --blue: #2563eb;\n            --body-text: #1f2937;\n            --grey-text: #667085;\n            --border: rgba(28, 36, 75, 0.14);\n            --shadow: 0 18px 45px rgba(28, 36, 75, 0.12);\n            --inner-shadow: 0 10px 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src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/05\/T1-Atomic-Structure-and-The-Periodic-Table.jpg\" alt=\"Edexcel A Level Chemistry Topic 1 Atomic Structure and The Periodic Table course banner\">\n              <\/div>\n      \n            <\/a>\n      \n            <div class=\"ols-course-cta-content\">\n      \n              <div class=\"ols-course-cta-header-row\">\n      \n                <div class=\"ols-course-cta-kicker\">\n                  Complete Topic 1 Atomic Structure &amp; The Periodic Table Course\n                <\/div>\n      \n                <a class=\"ols-course-button ols-course-button-top\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/atomic-structure-and-the-periodic-table-topic-1\/\">\n                  View Course\n                <\/a>\n      \n              <\/div>\n      \n              <h2>\n                Master Atomic Structure and The Periodic Table for Edexcel A Level Chemistry\n              <\/h2>\n      \n            <\/div>\n      \n          <\/div>\n      \n          <div class=\"ols-course-cta-intro-stats\">\n      \n            <p class=\"ols-course-cta-intro\">\n              Continue from these free revision notes into the full Topic 1 Atomic Structure and The Periodic Table course, with guided video teaching, diagnostic MCQ practice, teacher-marked short-answer questions and a specification assignment with a personalised progress report.\n            <\/p>\n      \n            <div class=\"ols-course-cta-stats\">\n      \n              <div class=\"ols-course-stat\">\n                <span>Guided learning<\/span>\n                <strong>18 hours<\/strong>\n              <\/div>\n      \n              <div class=\"ols-course-stat\">\n                <span>Video lessons<\/span>\n                <strong>369 mins<\/strong>\n              <\/div>\n      \n              <div class=\"ols-course-stat\">\n                <span>MCQ practice<\/span>\n                <strong>86 marks<\/strong>\n              <\/div>\n      \n              <div class=\"ols-course-stat\">\n                <span>SAQ practice<\/span>\n                <strong>215 marks<\/strong>\n              <\/div>\n      \n            <\/div>\n      \n          <\/div>\n      \n          <div class=\"ols-course-cta-features\">\n      \n            <div class=\"ols-course-feature\">\n              <h3>Guided video teaching<\/h3>\n              <p>\n                Learn atomic structure, isotopes, mass spectrometry, ionisation energy, electron configuration and periodic trends through structured video lessons with worked examples and walkthroughs.\n              <\/p>\n            <\/div>\n      \n            <div class=\"ols-course-feature\">\n              <h3>Instant MCQ feedback<\/h3>\n              <p>\n                Auto-marked MCQ quizzes provide immediate diagnostic feedback for every answer choice.\n              <\/p>\n            <\/div>\n      \n            <div class=\"ols-course-feature\">\n              <h3>Teacher-marked SAQs<\/h3>\n              <p>\n                Submit written exam responses and receive chemistry specialist feedback with improvement guidance.\n              <\/p>\n            <\/div>\n      \n            <div class=\"ols-course-feature\">\n              <h3>Progress tracking<\/h3>\n              <p>\n                Identify strengths and weaknesses across atomic structure, isotopes, mass spectrometry, ionisation energies, electron configuration and periodic trends with targeted reporting.\n              <\/p>\n            <\/div>\n      \n          <\/div>\n      \n          <div class=\"ols-course-animation-wrap\">\n      \n            <h3 class=\"ols-course-animation-title\">\n              See how the course works\n            <\/h3>\n      \n            <div class=\"ols-animation-frame-shell\">\n              <iframe id=\"olsCourseAnimationFrame002\" title=\"OLS course preview animation\" loading=\"lazy\" referrerpolicy=\"no-referrer\">\n              <\/iframe>\n      \n              <button class=\"ols-animation-start-overlay\" id=\"olsCourseAnimationStart002\" type=\"button\" aria-label=\"Play OLS course preview animation\">\n                <span class=\"ols-animation-start-content\">\n                  <span class=\"ols-animation-play-circle\" aria-hidden=\"true\">\n                    <span class=\"ols-animation-play-icon\"><\/span>\n                  <\/span>\n                  <span class=\"ols-animation-start-text\">\n                    Play course preview animation\n                  <\/span>\n                <\/span>\n              <\/button>\n      \n              <button class=\"ols-animation-pause-button\" id=\"olsCourseAnimationPause002\" type=\"button\" aria-label=\"Pause course preview animation\">\n                Pause\n              <\/button>\n            <\/div>\n      \n            <p class=\"ols-course-video-status\">\n              Click play to start the course preview animation.\n            <\/p>\n      \n          <\/div>\n      \n          <div class=\"ols-course-cta-bottom\">\n      \n            <a class=\"ols-course-button\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/product\/atomic-structure-and-the-periodic-table-topic-1\/\">\n              View Atomic Structure &amp; The Periodic Table Topic 1 Course\n            <\/a>\n      \n          <\/div>\n      \n        <\/div>\n      \n        <template id=\"olsCourseAnimationTemplate002\">\n\n\n\n<meta charset=\"UTF-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0\">\n<title>OLS Combined Promo Animation<\/title>\n\n<style>\n*{\n  box-sizing:border-box;\n}\n\n:root{\n  --ols-video-screen-w:1180;\n  --ols-video-screen-h:664;\n  --ols-video-screen-scale:1;\n\n  --ols-mcq-screen-w:1360;\n  --ols-mcq-screen-h:1130;\n  --ols-mcq-screen-scale:1;\n\n  --ols-saq-screen-w:1360;\n  --ols-saq-screen-h:965;\n  --ols-saq-screen-scale:1;\n}\n\nhtml,\nbody{\n  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white-space:pre-wrap;\n}\n\n.saq-teacher-cursor{\n  background:#075f3b;\n}\n\n\/* ============================================================\n   SMALL WINDOW PROTECTION\n============================================================ *\/\n\n@media(max-width:900px){\n\n  .ols-video-title,\n  .ols-mcq-intro-title,\n  .ols-saq-intro-title{\n    font-size:clamp(42px,11vw,78px);\n    line-height:1.12;\n  }\n\n  .ols-title-cursor{\n    width:4px;\n    margin-left:6px;\n  }\n\n  .ols-video-card{\n    border-radius:20px;\n  }\n\n}\n<\/style>\n\n\n\n\n<div class=\"ols-combined-stage\">\n\n  <!-- ========================================================\n       SCENE 1: VIRTUAL LESSON\n  ========================================================= -->\n\n  <section id=\"sceneVideo\" class=\"ols-scene active\">\n\n    <div class=\"ols-video-stage\">\n\n      <div id=\"videoTitleScreen\" class=\"ols-video-title-screen\">\n\n        <div class=\"ols-video-title-wrap\">\n          <h1 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class=\"ols-mcq-intro-title-wrap\">\n          <h1 class=\"ols-mcq-intro-title\">\n            <span id=\"mcqIntroTitleText\"><\/span><span id=\"mcqIntroTitleCursor\" class=\"ols-title-cursor\"><\/span>\n          <\/h1>\n        <\/div>\n      <\/div>\n\n      <div class=\"ols-mcq-scale-wrap\">\n\n        <main id=\"mcqScreen\" class=\"ols-mcq-screen\">\n\n          <section class=\"mcq-question-area\">\n\n            <p class=\"mcq-question-lead\">Some ionic radii are shown.<\/p>\n\n            <table class=\"mcq-ionic-table\">\n              <thead>\n                <tr>\n                  <th>Ion<\/th>\n                  <th>Ionic radius \/ nm<\/th>\n                <\/tr>\n              <\/thead>\n\n              <tbody>\n                <tr>\n                  <td>Na<sup>+<\/sup><\/td>\n                  <td>0.102<\/td>\n                <\/tr>\n\n                <tr>\n                  <td>K<sup>+<\/sup><\/td>\n                  <td>0.138<\/td>\n                <\/tr>\n\n                <tr>\n                  <td>F<sup>\u2212<\/sup><\/td>\n                  <td>0.133<\/td>\n                <\/tr>\n\n                <tr>\n                  <td>Cl<sup>\u2212<\/sup><\/td>\n                  <td>0.180<\/td>\n                <\/tr>\n              <\/tbody>\n            <\/table>\n\n            <p class=\"mcq-question-main\">Which compound has the strongest ionic bonding?<\/p>\n\n            <div class=\"mcq-options-wrap\">\n\n              <div id=\"mcqWrongOption\" class=\"mcq-option-row\">\n                <span class=\"mcq-radio\"><\/span>\n                <span class=\"mcq-radio-ripple\"><\/span>\n                <span class=\"mcq-option-label\">sodium chloride<\/span>\n\n                <span id=\"mcqSpecificFeedback\" class=\"mcq-specific-feedback\">\n                  <span id=\"mcqCrossIcon\" class=\"mcq-cross-icon\">\u00d7<\/span>\n                  <span class=\"mcq-specific-feedback-text\">\n                    <span id=\"mcqSpecificText\"><\/span><span id=\"mcqSpecificCursor\" class=\"cursor mcq-specific-cursor\" style=\"display:none;\"><\/span>\n                  <\/span>\n                <\/span>\n              <\/div>\n\n              <div class=\"mcq-option-row\">\n                <span class=\"mcq-radio\"><\/span>\n                <span class=\"mcq-radio-ripple\"><\/span>\n                <span class=\"mcq-option-label\">potassium chloride<\/span>\n              <\/div>\n\n              <div class=\"mcq-option-row\">\n                <span class=\"mcq-radio\"><\/span>\n                <span class=\"mcq-radio-ripple\"><\/span>\n                <span class=\"mcq-option-label\">sodium fluoride<\/span>\n              <\/div>\n\n              <div class=\"mcq-option-row\">\n                <span class=\"mcq-radio\"><\/span>\n                <span class=\"mcq-radio-ripple\"><\/span>\n                <span class=\"mcq-option-label\">potassium fluoride<\/span>\n              <\/div>\n\n            <\/div>\n\n            <button 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MULTIPLE CHOICE FEEDBACK\n============================================================ *\/\n\nconst mcqIntroTitle =\n\"Multiple Choice Question Bank\";\n\nconst mcqSpecificFeedbackText =\n\"Na\u207a is small, but Cl\u207b is larger than F\u207b, so the ionic bonding is weaker than in NaF.\";\n\nconst mcqGeneralFeedbackText =\n\"Your answer is incorrect.\\n\\n\" +\n\"To determine which compound has the strongest ionic bonding, recall the key principle:\\n\\n\" +\n\"\u2022 Ionic bond strength increases when ionic radii are small, because the ions can get closer together.\\n\" +\n\"\u2022 Smaller ions \u2192 stronger electrostatic attraction \u2192 stronger ionic lattice.\\n\" +\n\"\u2022 Na\u207a (0.102 nm) is smaller than K\u207a (0.138 nm).\\n\" +\n\"\u2022 F\u207b (0.133 nm) is smaller than Cl\u207b (0.180 nm).\\n\\n\" +\n\"Therefore, the strongest ionic bonding occurs in the compound formed by the smallest cation and the smallest anion \u2192 sodium fluoride (NaF).\\n\\n\" +\n\"The correct answer is: sodium fluoride\";\n\nconst mcqIntroScreen =\ndocument.getElementById(\"mcqIntroScreen\");\n\nconst mcqIntroTitleText =\ndocument.getElementById(\"mcqIntroTitleText\");\n\nconst mcqIntroTitleCursor =\ndocument.getElementById(\"mcqIntroTitleCursor\");\n\nconst mcqScreen =\ndocument.getElementById(\"mcqScreen\");\n\nconst mcqWrongOption =\ndocument.getElementById(\"mcqWrongOption\");\n\nconst mcqSubmitButton =\ndocument.getElementById(\"mcqSubmitButton\");\n\nconst mcqSpecificFeedback =\ndocument.getElementById(\"mcqSpecificFeedback\");\n\nconst mcqCrossIcon =\ndocument.getElementById(\"mcqCrossIcon\");\n\nconst mcqSpecificText =\ndocument.getElementById(\"mcqSpecificText\");\n\nconst mcqSpecificCursor =\ndocument.getElementById(\"mcqSpecificCursor\");\n\nconst mcqGeneralFeedback =\ndocument.getElementById(\"mcqGeneralFeedback\");\n\nconst mcqGeneralText =\ndocument.getElementById(\"mcqGeneralText\");\n\nconst mcqGeneralCursor =\ndocument.getElementById(\"mcqGeneralCursor\");\n\nfunction selectMcqWrongOption(){\n\n  mcqWrongOption.classList.add(\"clicking\");\n\n  setTimeout(() => {\n    mcqWrongOption.classList.add(\"selected\");\n  },220);\n\n  setTimeout(() => {\n    mcqWrongOption.classList.remove(\"clicking\");\n  },850);\n\n}\n\nfunction clickMcqSubmit(){\n\n  mcqSubmitButton.classList.add(\"clicked\");\n\n  setTimeout(() => {\n    mcqSubmitButton.classList.remove(\"clicked\");\n  },240);\n\n}\n\nfunction showMcqSpecificFeedback(){\n\n  mcqSpecificFeedback.classList.add(\"show\");\n\n  setTimeout(() => {\n    mcqCrossIcon.classList.add(\"show\");\n  },180);\n\n  setTimeout(() => {\n\n    mcqSpecificCursor.style.display = \"inline-block\";\n\n    typeWriter(mcqSpecificText,mcqSpecificFeedbackText,12,() => {\n\n      mcqSpecificCursor.style.display = \"none\";\n\n      setTimeout(() => {\n        showMcqGeneralFeedback();\n      },650);\n\n    });\n\n  },560);\n\n}\n\nfunction showMcqGeneralFeedback(){\n\n  mcqGeneralFeedback.classList.add(\"show\");\n\n  setTimeout(() => {\n\n    mcqGeneralCursor.style.display = \"inline-block\";\n\n    typeWriter(mcqGeneralText,mcqGeneralFeedbackText,8,() => {\n\n      mcqGeneralCursor.style.display = \"none\";\n\n      setTimeout(() => {\n\n        switchScene(sceneMcq,sceneSaq,() => {\n          startSaqIntro();\n        });\n\n      },2600);\n\n    });\n\n  },600);\n\n}\n\nfunction startMcqAnimation(){\n\n  fitMcqScreen();\n\n  mcqScreen.classList.add(\"show\");\n\n  setTimeout(() => {\n\n    selectMcqWrongOption();\n\n    setTimeout(() => {\n\n      clickMcqSubmit();\n\n      setTimeout(() => {\n\n        showMcqSpecificFeedback();\n\n      },620);\n\n    },1150);\n\n  },1300);\n\n}\n\nfunction startMcqIntro(){\n\n  fitMcqScreen();\n\n  setTimeout(() => {\n\n    typeWriter(mcqIntroTitleText,mcqIntroTitle,44,() => {\n\n      setTimeout(() => {\n\n        mcqIntroTitleCursor.style.display = \"none\";\n\n        setTimeout(() => {\n\n          mcqIntroScreen.classList.add(\"hide\");\n\n          setTimeout(() => {\n            startMcqAnimation();\n          },850);\n\n        },3000);\n\n      },250);\n\n    });\n\n  },700);\n\n}\n\n\/* ============================================================\n   3. SHORT ANSWER FEEDBACK\n============================================================ *\/\n\nconst saqIntroTitle =\n\"Chemistry Specialist\\nMarked Exam Feedback\";\n\nconst saqStudentAnswer =\n\"Magnesium has stronger metallic bonding because it has more atoms packed together and melts at a higher temperature than sodium.\";\n\nconst saqTeacherFeedbackText =\n\"Comment:\\n\" +\n\"This answer is not correct. Melting temperature is a result of bonding strength, not the cause of it.\\n\\n\" +\n\"In metallic bonding, positive metal ions are attracted to a sea of delocalised electrons. The strength of this attraction depends on the charge of the ions and the number of delocalised electrons.\\n\\n\" +\n\"Magnesium forms Mg\u00b2\u207a ions and contributes two delocalised electrons per atom, whereas sodium forms Na\u207a ions and contributes only one electron. This results in a stronger electrostatic attraction in magnesium. Additionally, Mg\u00b2\u207a ions have a higher charge density than Na\u207a ions, further strengthening the metallic bonding.\\n\\n\" +\n\"Next time, include:\\n\" +\n\"\u2022 Ion charge: magnesium forms Mg\u00b2\u207a, sodium forms Na\u207a \u2713\\n\" +\n\"\u2022 Delocalised electrons: magnesium provides more electrons to the sea \u2713\\n\" +\n\"\u2022 Charge density: smaller, more highly charged ions create stronger attraction \u2713\\n\\n\" +\n\"You were close. 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The remaining electrons are held more strongly by the nucleus, so more energy is needed to remove the next electron.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>What does a large jump in successive ionisation energy show?<\/h3>\n            <p>A large jump shows that the next electron is being removed from an inner shell closer to the nucleus. This electron experiences less shielding and stronger nuclear attraction.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>How can successive ionisation energies show the group number?<\/h3>\n            <p>Count how many electrons are removed before the first large jump. 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