{"id":4580,"date":"2026-05-30T06:12:32","date_gmt":"2026-05-30T05:12:32","guid":{"rendered":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/covalent-bonding\/nature-of-covalent-bonding\/"},"modified":"2026-10-25T12:14:47","modified_gmt":"2026-10-25T12:14:47","slug":"nature-of-covalent-bonding","status":"publish","type":"page","link":"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/covalent-bonding\/nature-of-covalent-bonding\/","title":{"rendered":"Nature of Covalent Bonding"},"content":{"rendered":"<script src=\"https:\/\/cdnjs.cloudflare.com\/ajax\/libs\/three.js\/r128\/three.min.js\"><\/script>\n\n<section class=\"ols-revision-page ols-nature-of-covalent-bonding-9ch0-page\">\n  <style>\n    .ols-revision-page {\n      --navy: #1C244B;\n      --blue: #2563eb;\n      --soft-blue: #eef4ff;\n      --soft-red: #fff7f7;\n      --soft-purple: 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transparent; }\n    .ols-figure-placeholder { background: #ffffff; border: 1px solid rgba(28, 36, 75, 0.12); border-radius: 22px; padding: 14px; margin: 18px 0 6px; }\n    .ols-figure-placeholder .ols-figure-caption p { margin: 10px 0 0; font-size: 14px; color: #667085; text-align: center; }\n<\/style>\n\n  <aside class=\"ols-sidebar\">\r\n  <div class=\"ols-sidebar-header\">\r\n    <h3>Revision Notes<\/h3>\r\n    <p>A Level Chemistry<\/p>\r\n  <\/div>\r\n\r\n  <div class=\"ols-topic-group\">\r\n    <h4>Topic 2 Bonding and Structure<\/h4>\r\n\r\n    <ul class=\"ols-topic-list\">\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/ionic-bonding\/\">Ionic Bonding<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/ionic-bonding\/nature-of-ionic-bonding\/\">Nature of Ionic Bonding<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/ionic-bonding\/polarisation-of-ions\/\">Polarisation of Ions<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/ionic-bonding\/physical-properties-of-ionic-compounds\/\">Physical Properties of Ionic Compounds<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/covalent-bonding\/\">Covalent Bonding<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/covalent-bonding\/nature-of-covalent-bonding\/\">Nature of Covalent Bonding<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/covalent-bonding\/dative-covalent-bonding\/\">Dative Covalent Bonding<\/a>\r\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/covalent-bonding\/giant-covalent-structures\/\">Giant Covalent Structures<\/a>\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/covalent-bonding\/electronegativity\/\">Electronegativity<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/\">Shapes of Molecules<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/linear\/\">Linear<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/trigonal-planar\/\">Trigonal Planar<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/tetrahedral\/\">Tetrahedral<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/trigonal-pyramidal\/\">Trigonal Pyramidal<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/bent\/\">Bent<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/trigonal-bipyramidal\/\">Trigonal Bipyramidal<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/octahedral\/\">Octahedral<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/square-planar\/\">Square Planar<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/square-pyramidal\/\">Square Pyramidal<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/distorted-t\/\">Distorted T<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/seesaw\/\">SeeSaw<\/a>\r\n          <\/li>\r\n        <\/ul>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/polar-molecules\/\">Polar Molecules<\/a>\r\n      <\/li>\r\n\r\n      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/metallic-bonding\/\">Metallic Bonding<\/a>\r\n\r\n        <ul class=\"ols-subtopic-list\">\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/metallic-bonding\/metallic-bonding-and-structure\/\">Metallic Bonding and Structure<\/a>\r\n          <\/li>\r\n          <li>\r\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/metallic-bonding\/physical-properties-of-metals\/\">Physical Properties of Metals<\/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-2-bonding-and-structure\/intermolecular-forces\/\">Intermolecular Forces<\/a>\n        <ul class=\"ols-subtopic-list\">\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/intermolecular-forces\/london-forces\/\">London Forces<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/intermolecular-forces\/permanent-dipole-dipole-forces\/\">Permanent Dipole-Dipole Forces<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/intermolecular-forces\/hydrogen-bonding\/\">Hydrogen Bonding<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/intermolecular-forces\/anomalous-properties-of-water\/\">Anomalous Properties of Water<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/intermolecular-forces\/boiling-temperature-trends\/\">Boiling Temperature Trends<\/a>\n          <\/li>\n          <li>\n            <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/intermolecular-forces\/choosing-solvents\/\">Choosing Solvents<\/a>\n          <\/li>\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-2-bonding-and-structure\/structure-types\/\">Structure Types<\/a>\r\n      <\/li>\r\n\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-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      <li>\r\n        <a href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-5-formulae-equations-and-amounts-of-substance\/\">Formulae, Equations &amp; Amounts<\/a>\r\n      <\/li>\r\n    <\/ul>\r\n  <\/div>\r\n<\/aside>\r\n\r\n<script>\r\n(function() {\r\n  function normalisePath(path) {\r\n    return String(path || '')\r\n      .split('?')[0]\r\n      .split('#')[0]\r\n      .replace(\/\\\/+$\/, '')\r\n      .toLowerCase();\r\n  }\r\n\r\n  function highlightActive() {\r\n    var sidebar = document.querySelector('.ols-sidebar');\r\n    if (!sidebar) return false;\r\n\r\n    var currentPath = normalisePath(window.location.pathname);\r\n    var links = sidebar.querySelectorAll('a[href]');\r\n    var matched = null;\r\n    var matchedLength = 0;\r\n\r\n    sidebar.querySelectorAll('.active, .active-main, .parent-active').forEach(function(item) {\r\n      item.classList.remove('active', 'active-main', 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\/\n        <span>Nature of Covalent Bonding<\/span>\n      <\/nav>\n\n      <header class=\"ols-title-card\">\n        <h1>Nature of Covalent Bonding<\/h1>\n        <p class=\"ols-page-intro\">A concise revision guide to the nature of covalent bonding, shared electron density, orbital overlap, sigma bonds, pi bonds, multiple bonds and dot-and-cross representations for Edexcel A Level Chemistry.<\/p>\n\n        <div class=\"ols-badges\">\n          <div class=\"ols-badge\">Unit: Paper 1<\/div>\n          <div class=\"ols-badge\">Topic 2: Bonding and Structure<\/div>\n          <div class=\"ols-badge\">9CH0\/01<\/div>\n        <\/div>\n      <\/header>\n<!-- 3D card: sigma-pi-bonds (26 Sep 2026) -->\n<!-- Copyright (c) 2026 Dr. Mohammed Al-Fatah, onlinelearningsystem.net. 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text-align:center; font-size:11px; font-style:italic; color:#aab0c0;\n}\n.ols-cc-sgpi-001 a{color:#aab0c0; text-decoration:none;}\n.ols-cc-sgpi-001 a:hover{text-decoration:underline;}\n.ols-sgpi-001 .sgpi-seg button{display:inline-flex; align-items:center;}\n.ols-sgpi-001 .sgpi-seg button .sgpi-n{display:inline-flex; align-items:center; justify-content:center; width:20px; height:20px; margin-right:9px; border-radius:50%; font-size:11px; font-weight:600; background:rgba(37,99,235,0.10); color:#2563eb; flex:0 0 auto;}\n.ols-sgpi-001 .sgpi-seg button[aria-pressed=\"true\"] .sgpi-n{background:#ffffff; color:#2563eb;}\n<\/style>\n\n<div class=\"sgpi-head\">\n  <h2 class=\"sgpi-title\">Sigma and Pi Bonds: End-On and Sideways Overlap<\/h2>\n  <p class=\"sgpi-sub\">Choose a step to watch atoms approach, their orbitals combine into a \u03c3 molecular orbital and then a \u03c0 molecular orbital, and see why a C=C bond cannot twist.<\/p>\n<\/div>\n\n<div class=\"sgpi-stage\" id=\"sgpiStage\">\n  <canvas class=\"sgpi-canvas\" id=\"sgpiCanvas\"><\/canvas>\n  <div class=\"sgpi-overlay\" id=\"sgpiOverlay\"><\/div>\n  <div class=\"sgpi-caption\" id=\"sgpiCaption\"><\/div>\n  <div class=\"sgpi-hint\" id=\"sgpiHint\">Drag to rotate<\/div>\n  <div class=\"sgpi-badges\" id=\"sgpiBadges\"><\/div>\n<\/div>\n\n<div class=\"sgpi-controls\">\n  <div class=\"sgpi-row\">\n    <span class=\"sgpi-rowlab\">Step<\/span>\n    <div class=\"sgpi-seg\" role=\"group\" aria-label=\"Step\">\n      <button type=\"button\" data-step=\"1\" aria-pressed=\"true\"><span class=\"sgpi-n\">1<\/span>Two atoms approach<\/button>\n      <button type=\"button\" data-step=\"2\" aria-pressed=\"false\"><span class=\"sgpi-n\">2<\/span>\u03c3 MO forms<\/button>\n      <button type=\"button\" data-step=\"3\" aria-pressed=\"false\"><span class=\"sgpi-n\">3<\/span>\u03c0 MO forms<\/button>\n      <button type=\"button\" data-step=\"4\" aria-pressed=\"false\"><span class=\"sgpi-n\">4<\/span>The nodal plane<\/button>\n      <button type=\"button\" data-step=\"5\" aria-pressed=\"false\"><span class=\"sgpi-n\">5<\/span>No rotation about C=C<\/button>\n    <\/div>\n  <\/div>\n\n  <div class=\"sgpi-row\">\n    <span class=\"sgpi-rowlab\">View<\/span>\n    <button type=\"button\" class=\"sgpi-pill\" id=\"sgpiResetV\">Reset view<\/button>\n  <\/div>\n<\/div>\n\n<div class=\"sgpi-info\">\n  <h3 id=\"sgpiInfoTitle\"><\/h3>\n  <p id=\"sgpiInfoText\"><\/p>\n  <div class=\"sgpi-facts\" id=\"sgpiFacts\"><\/div>\n  <div class=\"sgpi-key\">\n    <span><i class=\"k-ball\" style=\"background:#484e5c\"><\/i>Carbon<\/span>\n    <span><i class=\"k-ball\" style=\"background:#ececf0\"><\/i>Hydrogen<\/span>\n    <span><i class=\"k-ball\" style=\"background:#34aa48\"><\/i>Chlorine<\/span>\n    <span><i class=\"\" style=\"background:rgba(150,156,170,0.6)\"><\/i>1s orbital<\/span>\n    <span><i class=\"\" style=\"background:rgba(58,160,72,0.6)\"><\/i>3p orbital<\/span>\n    <span><i class=\"\" style=\"background:rgba(236,140,40,0.65)\"><\/i>p orbital<\/span>\n    <span><i class=\"\" style=\"background:rgba(240,188,40,0.75)\"><\/i>\u03c3 molecular orbital<\/span>\n    <span><i class=\"\" style=\"background:rgba(22,150,175,0.65)\"><\/i>\u03c0 molecular orbital<\/span>\n    <span><i class=\"\" style=\"background:rgba(220,50,50,0.14);border-color:rgba(200,40,40,0.7)\"><\/i>Nodal plane<\/span>\n  <\/div>\n<\/div>\n\n<script src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/JS\/sigma-pi-bonds.js?v=20261025p\"><\/script>\n<\/section>\n\n<p class=\"ols-cc-sgpi-001\">&copy; Dr. Mohammed Al-Fatah &#8211; <a href=\"https:\/\/www.onlinelearningsystem.net\" target=\"_blank\" rel=\"noopener\">onlinelearningsystem.net<\/a><\/p>\n\n\n      \n<section class=\"ols-h5p-card ols-h5p-inline ols-h5p-recap\">\n<span class=\"ols-h5p-kicker\">Before you start<\/span>\n<h2>GCSE Recap: Shared Pairs in Simple Molecules<\/h2>\n<p>Before you start, check the GCSE ideas about shared pairs that this page builds on.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-content\" data-content-id=\"669\"><\/div><\/div>\n<\/section>\n<article class=\"ols-note-card soft\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">1<\/div>\n          <h2>What Is a Covalent Bond?<\/h2>\n        <\/div>\n\n        <p>A <strong>covalent bond<\/strong> is a strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.<\/p>\n        <p>In a hydrogen molecule, X-ray diffraction evidence shows a high concentration of negative charge between the two hydrogen nuclei. This shared negative charge is attracted to both nuclei, so the attractive forces are greater than the repulsive forces.<\/p>\n        <p>The evidence is drawn as an <strong>electron density map<\/strong>.<\/p>\n<p>Each contour joins points of equal electron density, in the same way that contour lines on a map join points of equal height, so contours packed tightly between the two nuclei show where the shared charge is concentrated.<\/p>\n        <p>The bond is therefore strongest when there is a significant density of shared electrons between the bonded atoms.<\/p>\n\n        <div class=\"ols-definition-box\">\n          <p><strong>Definition:<\/strong> A covalent bond forms when atomic orbitals overlap and a pair of electrons is shared between two atoms. The shared electron density between the nuclei holds the atoms together.<\/p>\n        <\/div>\n\n        <div class=\"ols-figure-card\">\n<div class=\"ols-figure-image\"><img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/09\/fix-22.jpg\" alt=\"Electron density contour map of a hydrogen molecule, showing shared electron density between the two nuclei.\"><\/div>\n<div class=\"ols-figure-caption\"><p>The highest electron density is between the nuclei, which explains the attractive force in the covalent bond.<\/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>Quick Check: What Holds F\u2082 Together?<\/h2>\n<p>Choose the statement that explains why the two fluorine atoms stay together.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-165\" class=\"h5p-iframe\" data-content-id=\"165\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Covalent Bonding MCQ: The Forces Inside a Fluorine Molecule\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">2<\/div>\n          <h2>Orbital Overlap and Single Covalent Bonds<\/h2>\n        <\/div>\n\n        <p>Covalent bonds form when <strong>atomic orbitals overlap<\/strong>. The shared electrons occupy the overlapping region and are attracted by both nuclei.<\/p>\n        <p>In hydrogen, two 1s orbitals overlap to form a molecular orbital containing the shared pair of electrons. In chlorine, a pair of p orbitals overlap, with each chlorine atom contributing one unpaired electron.<\/p>\n        <p>A <strong>molecular orbital<\/strong> is the new orbital produced by the overlap. It belongs to both atoms and holds the shared pair.<\/p>\n        <p>The two orbitals that overlap need not be the same type, and the two atoms need not be the same element.<\/p>\n<p>An s orbital on one atom can overlap end-on with a p orbital on another atom, and the bond formed is still a single covalent bond.<\/p>\n<p>To decide which orbitals overlap, write the electron configuration of each atom and pick out the orbital that holds the unpaired electron.<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Molecule<\/th>\n                <th>Orbitals involved<\/th>\n                <th>Bond formed<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Molecule\"><strong>H<sub>2<\/sub><\/strong><\/td>\n                <td data-label=\"Orbitals involved\">Overlap of two 1s orbitals<\/td>\n                <td data-label=\"Bond formed\">A single covalent bond with electron density between the two nuclei<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Molecule\"><strong>Cl<sub>2<\/sub><\/strong><\/td>\n                <td data-label=\"Orbitals involved\">Overlap of two p orbitals, each containing one unpaired electron<\/td>\n                <td data-label=\"Bond formed\">A single covalent bond between the two chlorine atoms<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        \n\n        \n\n\n        <div class=\"ols-key-box\">\n          <p><strong>Key idea:<\/strong> The shared pair of electrons is not just drawn between atoms for convenience. It represents electron density in the overlapping region between the nuclei.<\/p>\n        <\/div>\n      <div class=\"ols-zoom-card\">\n<div class=\"ols-zoom-card-image\">\n<a class=\"ols-lightbox-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t3-cd-03-sigma-overlap.svg\" aria-label=\"Open image full screen\">\n<img decoding=\"async\" class=\"ols-zoomable-img ols-lightbox-target\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t3-cd-03-sigma-overlap.svg\" alt=\"End-on overlap in H\u2082 (1s + 1s), HCl (1s + 3p) and Cl\u2082 (3p + 3p), each giving a \u03c3 orbital concentrated between the nuclei\">\n<\/a>\n<\/div>\n<div class=\"ols-zoom-card-caption\"><p>End-on overlap of 1s or p orbitals gives a \u03c3 molecular orbital with electron density on the line between the two nuclei.<\/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>Quick Check: Which Orbitals Overlap?<\/h2>\n<p>Answer each quick question on the orbitals that overlap in a new molecule.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-164\" class=\"h5p-iframe\" data-content-id=\"164\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Covalent Bonding Quick Fire: Which Orbitals Overlap?\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">3<\/div>\n          <h2>Sigma Bonds and Pi Bonds<\/h2>\n        <\/div>\n\n        <p>A <strong>sigma, &sigma;, bond<\/strong> is formed by direct orbital overlap along the line between two nuclei. It is the first covalent bond formed between two atoms.<\/p>\n        <p>After a sigma bond has formed, it is sometimes possible for a <strong>pi, &pi;, bond<\/strong> to form. A pi bond is formed by the sideways overlap of p orbitals, creating electron density above and below the <strong>internuclear axis<\/strong>, the line joining the two nuclei.<\/p>\n        <p>In a planar molecule such as ethene that is the same as above and below the plane of the molecule, but it is not the same in every molecule.<\/p>\n<p>N&equiv;N is linear and has no molecular plane, and its two pi bonds lie at right angles to each other. Quote the internuclear axis and the answer is right every time.<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Bond type<\/th>\n                <th>How it forms<\/th>\n                <th>Electron density<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Bond type\"><strong>&sigma; bond<\/strong><\/td>\n                <td data-label=\"How it forms\">Direct overlap of orbitals along the internuclear axis<\/td>\n                <td data-label=\"Electron density\">Concentrated directly between the two nuclei<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Bond type\"><strong>&pi; bond<\/strong><\/td>\n                <td data-label=\"How it forms\">Sideways overlap of p orbitals after a &sigma; bond has already formed<\/td>\n                <td data-label=\"Electron density\">Above and below the internuclear axis, the line joining the two nuclei<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-figure-card ols-zoom-card medium\">\n          <div class=\"ols-figure-image ols-zoom-card-image\">\n            <img decoding=\"async\" class=\"ols-zoomable-img ols-lightbox-target\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t3-cd-02-pi-bond.svg\" alt=\"Two parallel p orbitals on adjacent carbon atoms replaced by a \u03c0 molecular orbital with lobes above and below the internuclear axis\">\n          <\/div>\n          <div class=\"ols-figure-caption ols-zoom-card-caption\">\n            <p>The sideways overlap of p orbitals produces two regions of electron density, one above and one below the molecular plane.<\/p>\n          <\/div>\n        <\/div>\n\n<!-- Copyright (c) 2026 Dr. Mohammed Al-Fatah, onlinelearningsystem.net. 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border:1px solid rgba(28,36,75,0.18);\n}\n.ols-ntrb-001 .ntrb-key i.k-ball{border-radius:50%;}\n\n@media (max-width:760px){\n  .ols-ntrb-001{padding:26px; border-radius:22px;}\n  .ols-ntrb-001 h2.ntrb-title{font-size:20.5px;}\n  .ols-ntrb-001 p.ntrb-sub{font-size:13.5px;}\n  .ols-ntrb-001 .ntrb-stage{height:400px;}\n  .ols-ntrb-001 .ntrb-rowlab{min-width:100%;}\n  .ols-ntrb-001 .ntrb-seg button{padding:9px 13px; font-size:13px;}\n  .ols-ntrb-001 .ntrb-lab{font-size:10.5px; padding:4px 8px;}\n  .ols-ntrb-001 .ntrb-lab.l-part{font-size:9.5px; padding:3px 7px;}\n  .ols-ntrb-001 .ntrb-lab.l-read{font-size:12px; padding:5px 9px;}\n  .ols-ntrb-001 .ntrb-caption{font-size:10.5px; padding:5px 9px; max-width:64%;}\n  .ols-ntrb-001 .ntrb-badge{font-size:10.5px; padding:4px 9px;}\n  .ols-ntrb-001 .ntrb-badge.b-eq{font-size:11px;}\n  .ols-ntrb-001 .ntrb-badges{max-width:calc(100% - 28px);}\n  .ols-ntrb-001 .ntrb-info{padding:18px;}\n}\n\/* on a phone the caption needs the full top row, so the drag hint goes *\/\n@media (max-width:480px){\n  .ols-ntrb-001 .ntrb-hint{display:none;}\n  .ols-ntrb-001 .ntrb-caption{max-width:calc(100% - 28px);}\n}\n@media (prefers-reduced-motion:reduce){\n  .ols-ntrb-001 .ntrb-seg button,.ols-ntrb-001 .ntrb-pill{transition:none;}\n}\n\n.ols-cc-ntrb-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-ntrb-001 a{color:#aab0c0; text-decoration:none;}\n.ols-cc-ntrb-001 a:hover{text-decoration:underline;}\n.ols-ntrb-001 .ntrb-seg button{display:inline-flex; align-items:center;}\n.ols-ntrb-001 .ntrb-seg button .ntrb-n{display:inline-flex; align-items:center; justify-content:center; width:20px; height:20px; margin-right:9px; border-radius:50%; font-size:11px; font-weight:600; background:rgba(37,99,235,0.10); color:#2563eb; flex:0 0 auto;}\n.ols-ntrb-001 .ntrb-seg button[aria-pressed=\"true\"] .ntrb-n{background:#ffffff; color:#2563eb;}\n<\/style>\n\n<div class=\"ntrb-head\">\n  <h2 class=\"ntrb-title\">Bonding in Nitrogen, N\u2082: sp Hybrids, Sigma and Pi Bonds<\/h2>\n  <p class=\"ntrb-sub\">Choose a step to watch two nitrogen atoms build a triple bond: one \u03c3 bond, then two \u03c0 bonds at right angles, with a lone pair left on each atom.<\/p>\n<\/div>\n\n<div class=\"ntrb-stage\" id=\"ntrbStage\">\n  <canvas class=\"ntrb-canvas\" id=\"ntrbCanvas\"><\/canvas>\n  <div class=\"ntrb-overlay\" id=\"ntrbOverlay\"><\/div>\n  <div class=\"ntrb-caption\" id=\"ntrbCaption\"><\/div>\n  <div class=\"ntrb-hint\" id=\"ntrbHint\">Drag to rotate<\/div>\n  <div class=\"ntrb-badges\" id=\"ntrbBadges\"><\/div>\n<\/div>\n\n<div class=\"ntrb-controls\">\n  <div class=\"ntrb-row\">\n    <span class=\"ntrb-rowlab\">Step<\/span>\n    <div class=\"ntrb-seg\" role=\"group\" aria-label=\"Step\">\n      <button type=\"button\" data-step=\"1\" aria-pressed=\"true\"><span class=\"ntrb-n\">1<\/span>The orbitals<\/button>\n      <button type=\"button\" data-step=\"2\" aria-pressed=\"false\"><span class=\"ntrb-n\">2<\/span>\u03c3 bond forms<\/button>\n      <button type=\"button\" data-step=\"3\" aria-pressed=\"false\"><span class=\"ntrb-n\">3<\/span>First \u03c0 bond<\/button>\n      <button type=\"button\" data-step=\"4\" aria-pressed=\"false\"><span class=\"ntrb-n\">4<\/span>Second \u03c0 bond<\/button>\n      <button type=\"button\" data-step=\"5\" aria-pressed=\"false\"><span class=\"ntrb-n\">5<\/span>Lone pairs<\/button>\n    <\/div>\n  <\/div>\n\n  <div class=\"ntrb-row\">\n    <span class=\"ntrb-rowlab\">View<\/span>\n    <button type=\"button\" class=\"ntrb-pill\" id=\"ntrbResetV\">Reset view<\/button>\n  <\/div>\n<\/div>\n\n<div class=\"ntrb-info\">\n  <h3 id=\"ntrbInfoTitle\"><\/h3>\n  <p id=\"ntrbInfoText\"><\/p>\n  <div class=\"ntrb-facts\" id=\"ntrbFacts\"><\/div>\n  <div class=\"ntrb-key\">\n    <span><i class=\"k-ball\" style=\"background:#3056ce\"><\/i>Nitrogen nucleus<\/span>\n    <span><i class=\"k-ball\" style=\"background:#facc28\"><\/i>Electron<\/span>\n    <span><i class=\"\" style=\"background:rgba(90,140,220,0.55)\"><\/i>sp hybrid orbital<\/span>\n    <span><i class=\"\" style=\"background:rgba(60,170,110,0.55)\"><\/i>Lone pair (non-bonding sp hybrid)<\/span>\n    <span><i class=\"\" style=\"background:rgba(150,90,200,0.55)\"><\/i>2p\u1d22 orbital, or the \u03c0 MO it forms<\/span>\n    <span><i class=\"\" style=\"background:rgba(20,150,160,0.55)\"><\/i>2p\u1d67 orbital, or the \u03c0 MO it forms<\/span>\n    <span><i class=\"\" style=\"background:rgba(226,150,30,0.6)\"><\/i>\u03c3 molecular orbital<\/span>\n  <\/div>\n<\/div>\n\n<script src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/JS\/n2-bonding.js?v=20261025p\"><\/script>\n<\/section>\n\n<p class=\"ols-cc-ntrb-001\">&copy; Dr. Mohammed Al-Fatah &#8211; <a href=\"https:\/\/www.onlinelearningsystem.net\" target=\"_blank\" rel=\"noopener\">onlinelearningsystem.net<\/a><\/p>\n\n      <\/article>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Sigma or Pi?<\/h2>\n<p>Decide what type of bond forms in hydrogen chloride and why.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-166\" class=\"h5p-iframe\" data-content-id=\"166\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Covalent Bonding MCQ: Sigma or Pi in Hydrogen Chloride?\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card orange\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">4<\/div>\n          <h2>Double Bonds, Triple Bonds and Bond Strength<\/h2>\n        <\/div>\n\n        <p>A double bond contains <strong>one &sigma; bond and one &pi; bond<\/strong>. For example, the carbon-carbon double bond in ethene contains one sigma bond and one pi bond.<\/p>\n        <p>A triple bond contains <strong>one &sigma; bond and two &pi; bonds<\/strong>. For example, the nitrogen molecule, N&equiv;N, contains one sigma bond and two pi bonds.<\/p>\n        <p>Double and triple bonds place a greater electron density between the nuclei. This increases the electrostatic attraction between nuclei and bonding electrons, giving a <strong>shorter bond<\/strong> and a <strong>stronger bond<\/strong>.<\/p>\n        <p>A &pi; bond is <strong>weaker<\/strong> than a &sigma; bond. Sideways overlap is less effective than end-on overlap, so the electron density of a &pi; bond lies further from the two nuclei and is held less strongly.<\/p>\n<p>That is why the enthalpy of a C=C bond is less than twice the enthalpy of a C-C bond, and why it is the &pi; bond that breaks in the reactions of alkenes.<\/p>\n\n        <div class=\"ols-table-wrap\">\n          <table class=\"ols-table\">\n            <thead>\n              <tr>\n                <th>Bond<\/th>\n                <th>Bond length \/ nm<\/th>\n                <th>Mean bond enthalpy \/ kJ mol\u207b\u00b9<\/th>\n              <\/tr>\n            <\/thead>\n            <tbody>\n              <tr>\n                <td data-label=\"Bond\"><strong>C-C<\/strong><\/td>\n                <td data-label=\"Bond length \/ nm\">0.154<\/td>\n                <td data-label=\"Mean bond enthalpy\">+347<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Bond\"><strong>C=C<\/strong><\/td>\n                <td data-label=\"Bond length \/ nm\">0.134<\/td>\n                <td data-label=\"Mean bond enthalpy\">+612<\/td>\n              <\/tr>\n              <tr>\n                <td data-label=\"Bond\"><strong>C&equiv;C<\/strong><\/td>\n                <td data-label=\"Bond length \/ nm\">0.120<\/td>\n                <td data-label=\"Mean bond enthalpy\">+838<\/td>\n              <\/tr>\n            <\/tbody>\n          <\/table>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Exam focus:<\/strong> More shared electron pairs usually means greater electron density between nuclei, stronger attraction, shorter bond length and greater bond strength.<\/p>\n        <\/div>\n\n        <div class=\"ols-figure-card\">\n<div class=\"ols-figure-image\"><img decoding=\"async\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t3-cd-04-double-triple.svg\" alt=\"Dot-and-cross and displayed formulae for ethene (C=C, 1 \u03c3 + 1 \u03c0) and nitrogen (N\u2261N with lone pairs, 1 \u03c3 + 2 \u03c0)\" width=\"1520\" height=\"1187\"><\/div>\n<div class=\"ols-figure-caption\"><p>Multiple bonds contain more shared electron pairs, which changes both bond length and bond strength.<\/p><\/div>\n<\/div>\n\n        \n      <div class=\"ols-zoom-card\">\n<div class=\"ols-zoom-card-image\">\n<a class=\"ols-lightbox-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t3-img-07-bondorder.jpg\" aria-label=\"Open image full screen\">\n<img decoding=\"async\" class=\"ols-zoomable-img ols-lightbox-target\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t3-img-07-bondorder.jpg\" alt=\"Bars comparing C\u2013C, C=C and C\u2261C: length falls from 0.154 to 0.120 nm while bond enthalpy rises from 347 to 838 kJ mol\u207b\u00b9\">\n<\/a>\n<\/div>\n<div class=\"ols-zoom-card-caption\"><p>More shared pairs give a shorter, stronger bond, but each \u03c0 bond adds less strength than the \u03c3 bond.<\/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>Quick Check: Count the Sigma and Pi Bonds<\/h2>\n<p>Count the \u03c3 and \u03c0 bonds in each molecule and type the numbers.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-167\" class=\"h5p-iframe\" data-content-id=\"167\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Covalent Bonding Fill In: Counting Sigma and Pi Bonds in Four Molecules\"><\/iframe><\/div><\/div>\n<\/section>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: Explain Bond Length and Strength<\/h2>\n<p>Write a short explanation, then compare it with the mark points and the model answer.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-670\" class=\"h5p-iframe\" data-content-id=\"670\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Covalent Bonding Explain: Carbon-Oxygen Single and Double Bonds\"><\/iframe><\/div><\/div>\n<\/section>\n\n      <article class=\"ols-note-card\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">5<\/div>\n          <h2>Dot-and-Cross Diagrams and Electron Configuration<\/h2>\n        <\/div>\n\n        <p><strong>Dot-and-cross diagrams<\/strong> show how outer shell electrons are shared in covalent bonds. Only the outer shell electrons are normally shown.<\/p>\n        <p>Many atoms reach eight electrons in their outer shell when they bond, a stable arrangement often described as the <strong>octet rule<\/strong>. Hydrogen is an exception, because it becomes stable with two electrons in its outer shell.<\/p>\n        <p>The octet rule is a guide, not a law. Some central atoms finish with fewer than eight outer electrons, and some from Period 3 onwards finish with more, so count the pairs you have actually drawn instead of assuming eight.<\/p>\n\n        <div class=\"ols-rule-list\">\n          <div class=\"ols-rule-item\">\n            <h3>Single bond<\/h3>\n            <p>One shared pair of electrons is shown between the two atoms.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Double bond<\/h3>\n            <p>Two shared pairs of electrons are shown between the two atoms.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Triple bond<\/h3>\n            <p>Three shared pairs of electrons are shown between the two atoms.<\/p>\n          <\/div>\n        <\/div>\n\n        <div class=\"ols-key-box\">\n          <p><strong>Remember:<\/strong> Dot-and-cross diagrams show electron sharing, but orbital overlap explains why the shared electrons hold the nuclei together.<\/p>\n        <\/div>\n      <div class=\"ols-zoom-card\">\n<div class=\"ols-zoom-card-image\">\n<a class=\"ols-lightbox-link\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t3-cd-05-dotcross-set.svg\" aria-label=\"Open image full screen\">\n<img decoding=\"async\" class=\"ols-zoomable-img ols-lightbox-target\" src=\"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-content\/uploads\/2026\/10\/t3-cd-05-dotcross-set.svg\" alt=\"Dot-and-cross diagrams in three columns: single bonds in Cl\u2082 and HCl, double bonds in O\u2082 and CO\u2082, triple bonds in HCN and ethyne\">\n<\/a>\n<\/div>\n<div class=\"ols-zoom-card-caption\"><p>Dot-and-cross diagrams with one, two and three shared pairs: Cl\u2082 and HCl, O\u2082 and CO\u2082, HCN and ethyne.<\/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>Quick Check: Pairs in New Dot-and-Cross Diagrams<\/h2>\n<p>Sketch each dot-and-cross diagram on paper, then type the number of pairs.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-671\" class=\"h5p-iframe\" data-content-id=\"671\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Covalent Bonding Flashcards: Counting Pairs in Dot-and-Cross Diagrams\"><\/iframe><\/div><\/div>\n<\/section>\n<section class=\"ols-h5p-card ols-h5p-inline\">\n<span class=\"ols-h5p-kicker\">Check your understanding<\/span>\n<h2>Quick Check: The Whole Page in Five Statements<\/h2>\n<p>In each round, pick the one accurate statement to review everything on this page.<\/p>\n<div class=\"ols-h5p-frame\"><div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-1293\" class=\"h5p-iframe\" data-content-id=\"1293\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"Covalent Bonding Summary: Shared Pairs, Overlap and Bond Length Reviewed\"><\/iframe><\/div><\/div>\n<\/section>\n\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\n        <p>Strong covalent bonding answers link electron sharing to <strong>electrostatic attraction<\/strong>, <strong>orbital overlap<\/strong> and the location of <strong>electron density<\/strong>.<\/p>\n\n        <div class=\"ols-rule-list\">\n          <div class=\"ols-rule-item\">\n            <h3>Do not say electrons are simply transferred<\/h3>\n            <p>Covalent bonding involves shared electron pairs. Electron transfer is used to explain ionic bonding.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Use attraction between nuclei and shared electrons<\/h3>\n            <p>The bond is held by electrostatic attraction between the positively charged nuclei and the shared negative electron density.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Distinguish &sigma; and &pi; bonds clearly<\/h3>\n            <p>A sigma bond forms by direct overlap along the internuclear axis. A pi bond forms by sideways overlap of p orbitals.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Link multiple bonds to electron density<\/h3>\n            <p>Double and triple bonds have greater electron density between the nuclei, so they are generally shorter and stronger than single bonds between the same atoms.<\/p>\n          <\/div>\n        <\/div>\n      <\/article>\n\n      \n\n      <article class=\"ols-note-card purple\">\n        <div class=\"ols-note-title\">\n          <div class=\"ols-note-icon\">\u2713<\/div>\n          <h2>QuickSnap<\/h2>\n        <\/div>\n\n        <p>Covalent bonding is explained by <strong>shared electron density<\/strong> between bonded atoms. This electron density is attracted to both nuclei, holding the atoms together.<\/p>\n\n        <div class=\"ols-rule-list\">\n          <div class=\"ols-rule-item\">\n            <h3>Covalent bond<\/h3>\n            <p>A shared pair of electrons attracted to the nuclei of both bonded atoms.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Orbital overlap<\/h3>\n            <p>Atomic orbitals overlap, and the shared electrons occupy the overlapping region.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>&sigma; bond<\/h3>\n            <p>Forms by direct overlap along the internuclear axis, with electron density between the nuclei.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>&pi; bond<\/h3>\n            <p>Forms by sideways overlap of p orbitals, with electron density above and below the internuclear axis. It is weaker than a &sigma; bond.<\/p>\n          <\/div>\n          <div class=\"ols-rule-item\">\n            <h3>Multiple bonds<\/h3>\n            <p>Double bonds contain one &sigma; and one &pi; bond. Triple bonds contain one &sigma; and two &pi; bonds.<\/p>\n          <\/div>\n        <\/div>\n      <\/article>\n\n            <section class=\"ols-faq-card\">\n        <h2>FAQs<\/h2>\n        <p>Use these quick answers to check the common covalent bonding ideas that appear in Edexcel A Level Chemistry questions.<\/p>\n\n        <div class=\"ols-faq-list\">\n          <div class=\"ols-faq-item\">\n            <h3>What is a covalent bond?<\/h3>\n            <p>A covalent bond is a strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>Why is electron density important in covalent bonding?<\/h3>\n            <p>The shared electron density lies between the nuclei and is attracted to both positively charged nuclei. This attraction holds the atoms together.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>What is the difference between a sigma bond and a pi bond?<\/h3>\n            <p>A sigma bond forms by direct orbital overlap along the internuclear axis. A pi bond forms by sideways overlap of p orbitals and has electron density above and below that same axis. A pi bond is weaker than a sigma bond.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>How many sigma and pi bonds are in a double bond?<\/h3>\n            <p>A double bond contains one sigma bond and one pi bond.<\/p>\n          <\/div>\n\n          <div class=\"ols-faq-item\">\n            <h3>How many sigma and pi bonds are in a triple bond?<\/h3>\n            <p>A triple bond contains one sigma bond and two pi bonds.<\/p>\n          <\/div>\n        <\/div>\n      <\/section>\n\n      <!-- author card (moved to the end, 10 Oct 2026) -->\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:<br><span>Dr. Mohammed Al-Fatah<\/span>\n      <\/h2>\n\n      <p class=\"ols-author-description\">\n        Chemistry specialist revision notes for A Level Chemistry.\n      <\/p>\n\n      <a\n        class=\"ols-linkedin-pill\"\n        href=\"https:\/\/www.linkedin.com\/in\/doctormohammedfatah\/\"\n        target=\"_blank\"\n        rel=\"noopener noreferrer\"\n      >\n        <svg class=\"ols-linkedin-icon\" viewBox=\"0 0 24 24\" fill=\"currentColor\" aria-hidden=\"true\">\n          <path d=\"M4.98 3.5C4.98 4.88 3.86 6 2.48 6S0 4.88 0 3.5 1.12 1 2.48 1s2.5 1.12 2.5 2.5zM.5 8h4V24h-4V8zm7 0h3.8v2.2h.1c.5-.9 1.8-2.2 3.9-2.2 4.2 0 5 2.8 5 6.4V24h-4v-7.6c0-1.8 0-4.2-2.6-4.2s-3 2-3 4v7.8h-4V8z\"\/>\n        <\/svg>\n        View LinkedIn Profile\n      <\/a>\n\n    <\/div>\n\n  <\/div>\n\n\n<section class=\"ols-related-card\">\n        <h2>Related Topics<\/h2>\n        <p>Continue through Topic 2 Bonding and Structure with the next linked revision notes.<\/p>\n\n        <div class=\"ols-related-grid\">\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/covalent-bonding\/dative-covalent-bonding\/\">Dative Covalent Bonding<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/covalent-bonding\/electronegativity\/\">Electronegativity<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/shapes-of-molecules\/\">Shapes of Molecules<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/polar-molecules\/\">Non-Polar &amp; Polar Molecules<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/ionic-bonding\/nature-of-ionic-bonding\/\">Nature of Ionic Bonding<\/a>\n          <a class=\"ols-related-item\" href=\"https:\/\/www.onlinelearningsystem.net\/xyz\/revision-notes\/a-level-chemistry\/edexcel\/topic-2-bonding-and-structure\/metallic-bonding\/metallic-bonding-and-structure\/\">Metallic Bonding and Structure<\/a>\n        <\/div>\n      <\/section>\n\n      <section class=\"ols-attribution-card ols-attr-std\" aria-label=\"Copyright notice\">\n<style id=\"ols-attribution-card-css\">.ols-attribution-card.ols-attr-std{background:linear-gradient(135deg,#ffffff,#f8fbff);border:1px solid rgba(28,36,75,0.14);border-radius:28px;box-shadow:0 18px 45px rgba(28,36,75,0.10);padding:34px;margin:24px 0;overflow:hidden;font-family:Poppins,Arial,sans-serif;box-sizing:border-box}.ols-attribution-card.ols-attr-std *{box-sizing:border-box}.ols-attribution-card.ols-attr-std p{margin:0;font-size:14px;line-height:1.65;font-weight:300;color:#667085}.ols-attribution-card.ols-attr-std strong{font-weight:700;color:#1C244B}@media (max-width:760px){.ols-attribution-card.ols-attr-std{padding:24px 18px;border-radius:22px}}<\/style>\n<p><strong>Copyright notice:<\/strong> This OLS revision content, including the explanations, layout, diagrams, tables and embedded learning structure, is authored for Online Learning System by Dr. Mohammed Al-Fatah. It may not be copied, reproduced, redistributed or adapted without written permission.<\/p>\n<\/section>\n\n      <div class=\"ols-image-lightbox\" id=\"olsImageLightboxNatureCovalentBonding9ch0\" aria-hidden=\"true\" role=\"dialog\" aria-modal=\"true\" aria-label=\"Expanded revision image\">\n        <div class=\"ols-image-lightbox-inner\">\n          <button class=\"ols-image-lightbox-close\" type=\"button\" aria-label=\"Close enlarged image\">\u00d7<\/button>\n          <img decoding=\"async\" class=\"ols-image-lightbox-img\" src=\"\" alt=\"\">\n        <\/div>\n      <\/div>\n\n      <script>\n        (function(){\n          var page = document.querySelector(\".ols-nature-of-covalent-bonding-9ch0-page\");\n          if (!page) { return; }\n          var lightbox = page.querySelector(\"#olsImageLightboxNatureCovalentBonding9ch0\");\n          if (!lightbox) { return; }\n          var lightboxImage = lightbox.querySelector(\".ols-image-lightbox-img\");\n          var closeButton = 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[&hellip;]<\/p>\n","protected":false},"author":12,"featured_media":0,"parent":4571,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-4580","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4580","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=4580"}],"version-history":[{"count":2,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4580\/revisions"}],"predecessor-version":[{"id":24830,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4580\/revisions\/24830"}],"up":[{"embeddable":true,"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/pages\/4571"}],"wp:attachment":[{"href":"https:\/\/www.onlinelearningsystem.net\/xyz\/wp-json\/wp\/v2\/media?parent=4580"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}