{"id":2242,"date":"2026-10-13T20:54:22","date_gmt":"2026-10-13T15:24:22","guid":{"rendered":"https:\/\/www.tiwaripedia.com\/index.php\/2026\/10\/13\/periodic-table-explained\/"},"modified":"2026-10-13T21:18:34","modified_gmt":"2026-10-13T15:48:34","slug":"periodic-table-explained","status":"publish","type":"post","link":"https:\/\/www.tiwaripedia.com\/index.php\/2026\/10\/13\/periodic-table-explained\/","title":{"rendered":"The Periodic Table Explained: Groups, Periods and the First 20 Elements"},"content":{"rendered":"<p><em>Last updated: October 2026 \u00b7 3 min read<\/em><\/p>\n<p>Everything around you, from air to your phone, is made of chemical <b>elements<\/b>. The <b>periodic table<\/b> arranges all 118 known elements in a grid so their properties follow clear patterns.<\/p>\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" loading=\"lazy\" width=\"1200\" height=\"675\" src=\"https:\/\/www.tiwaripedia.com\/wp-content\/uploads\/2026\/10\/periodic-table-explained.png\" alt=\"Infographic: The Periodic Table Explained: Groups, Periods and the First 20 Elements\" class=\"wp-image-2241\" srcset=\"https:\/\/www.tiwaripedia.com\/wp-content\/uploads\/2026\/10\/periodic-table-explained.png 1200w, https:\/\/www.tiwaripedia.com\/wp-content\/uploads\/2026\/10\/periodic-table-explained-300x169.png 300w, https:\/\/www.tiwaripedia.com\/wp-content\/uploads\/2026\/10\/periodic-table-explained-1024x576.png 1024w, https:\/\/www.tiwaripedia.com\/wp-content\/uploads\/2026\/10\/periodic-table-explained-768x432.png 768w\" sizes=\"(max-width: 1200px) 100vw, 1200px\" \/><figcaption>The Periodic Table Explained: Groups, Periods and the First 20 Elements \u2013 infographic by Tiwaripedia<\/figcaption><\/figure>\n<h2>Who created the periodic table?<\/h2>\n<p>Russian chemist <b>Dmitri Mendeleev<\/b> published his table in 1869, arranging elements by atomic mass and leaving gaps for elements not yet discovered. Today the table is ordered by <b>atomic number<\/b>, the number of protons in an atom.<\/p>\n<h2>Periods and groups<\/h2>\n<ul><li><b>Periods<\/b> are the 7 horizontal rows. Elements in the same period have the same number of electron shells.<\/li><li><b>Groups<\/b> are the 18 vertical columns. Elements in a group have similar chemical behaviour because they have the same number of outer electrons.<\/li><\/ul>\n<h2>Important groups<\/h2>\n<figure class=\"wp-block-table\"><table><thead><tr><th>Group<\/th><th>Name<\/th><th>Examples<\/th><th>Key property<\/th><\/tr><\/thead><tbody><tr><td>1<\/td><td>Alkali metals<\/td><td>Sodium, potassium<\/td><td>Very reactive with water<\/td><\/tr><tr><td>2<\/td><td>Alkaline earth metals<\/td><td>Calcium, magnesium<\/td><td>Reactive, found in bones and rocks<\/td><\/tr><tr><td>17<\/td><td>Halogens<\/td><td>Chlorine, fluorine<\/td><td>Reactive non-metals used in disinfectants<\/td><\/tr><tr><td>18<\/td><td>Noble gases<\/td><td>Helium, neon, argon<\/td><td>Very unreactive<\/td><\/tr><tr><td>3-12<\/td><td>Transition metals<\/td><td>Iron, copper, gold<\/td><td>Strong, conduct electricity<\/td><\/tr><\/tbody><\/table><\/figure>\n<h2>The first 20 elements<\/h2>\n<figure class=\"wp-block-table\"><table><thead><tr><th>No.<\/th><th>Element<\/th><th>Symbol<\/th><th>No.<\/th><th>Element<\/th><th>Symbol<\/th><\/tr><\/thead><tbody><tr><td>1<\/td><td>Hydrogen<\/td><td>H<\/td><td>11<\/td><td>Sodium<\/td><td>Na<\/td><\/tr><tr><td>2<\/td><td>Helium<\/td><td>He<\/td><td>12<\/td><td>Magnesium<\/td><td>Mg<\/td><\/tr><tr><td>3<\/td><td>Lithium<\/td><td>Li<\/td><td>13<\/td><td>Aluminium<\/td><td>Al<\/td><\/tr><tr><td>4<\/td><td>Beryllium<\/td><td>Be<\/td><td>14<\/td><td>Silicon<\/td><td>Si<\/td><\/tr><tr><td>5<\/td><td>Boron<\/td><td>B<\/td><td>15<\/td><td>Phosphorus<\/td><td>P<\/td><\/tr><tr><td>6<\/td><td>Carbon<\/td><td>C<\/td><td>16<\/td><td>Sulphur<\/td><td>S<\/td><\/tr><tr><td>7<\/td><td>Nitrogen<\/td><td>N<\/td><td>17<\/td><td>Chlorine<\/td><td>Cl<\/td><\/tr><tr><td>8<\/td><td>Oxygen<\/td><td>O<\/td><td>18<\/td><td>Argon<\/td><td>Ar<\/td><\/tr><tr><td>9<\/td><td>Fluorine<\/td><td>F<\/td><td>19<\/td><td>Potassium<\/td><td>K<\/td><\/tr><tr><td>10<\/td><td>Neon<\/td><td>Ne<\/td><td>20<\/td><td>Calcium<\/td><td>Ca<\/td><\/tr><\/tbody><\/table><\/figure><p><b>Memory trick:<\/b> &#8220;Hi Hello Little Beautiful Baby, Can Not Open Fridge Now. Nana Maggi Always Sees People Sitting Clean And Kind Ca(lm).&#8221;<\/p>\n<h2>Metals, non-metals and metalloids<\/h2>\n<p>Metals sit on the left and centre, are shiny and conduct electricity. Non-metals are on the right. A zig-zag line separates them, with <b>metalloids<\/b> such as silicon and germanium, used in computer chips, along the border.<\/p>\n<h2>Frequently asked questions<\/h2>\n<h3>How many elements are there?<\/h3>\n<p>118 confirmed elements. The latest four, including nihonium and oganesson, were officially named in 2016.<\/p>\n<h3>Why are some symbols different from names?<\/h3>\n<p>They come from Latin names: Na from natrium (sodium), K from kalium (potassium), Fe from ferrum (iron).<\/p>\n<h3>Which is the most abundant element?<\/h3>\n<p>Hydrogen in the universe; oxygen in Earth&#8217;s crust and in the human body by mass.<\/p>\n<h2>Keep exploring<\/h2>\n<ul><li><a href=\"\/index.php\/2026\/10\/12\/states-of-matter-explained\/\">States of matter explained<\/a><\/li><li><a href=\"\/index.php\/2026\/10\/12\/dna-explained\/\">DNA explained<\/a><\/li><li><a href=\"\/index.php\/2026\/10\/12\/photosynthesis-explained\/\">Photosynthesis explained<\/a><\/li><li><a href=\"\/index.php\/category\/science\/\">More Science articles on Tiwaripedia<\/a><\/li><\/ul>\n<p><em>Facts are based on widely accepted official, scientific and historical sources at the time of writing. Spotted something that needs updating? <a href=\"\/index.php\/contact-us\/\">Let us know<\/a>.<\/em><\/p>","protected":false},"excerpt":{"rendered":"<p>The periodic table made simple: who made it, how groups and periods work, metals vs non-metals, and the first 20 elements with symbols and an easy memory trick.<\/p>\n","protected":false},"author":1,"featured_media":2241,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"googlesitekit_rrm_CAow_YXIDA:productID":""},"categories":[5],"tags":[],"_links":{"self":[{"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/posts\/2242"}],"collection":[{"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/comments?post=2242"}],"version-history":[{"count":1,"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/posts\/2242\/revisions"}],"predecessor-version":[{"id":2503,"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/posts\/2242\/revisions\/2503"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/media\/2241"}],"wp:attachment":[{"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/media?parent=2242"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/categories?post=2242"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tiwaripedia.com\/index.php\/wp-json\/wp\/v2\/tags?post=2242"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}