In a periodic table, chemical elements are arranged in groups and periods according to their atomic number, electron configuration, and their chemical properties.

Elements in the same period have the same number of electron shells and tend to have similar properties. Thus, it is relatively easy to predict the chemical properties of an element if one knows the properties of the elements around it. A new row (period) is started when a new electron shell has its first electron.

Elements in the same group have the same electron configuration in their valence shell.

Overview of all known elements categorized by atomic number. Column 1 from row 1 to 8 includes 1 Hydrogen, 3 Lithium, 11 Sodium, 19 Potassium, 37 Rubidium, 55 Cesium, 87 Francium, and 119 Ununennium. Column 2 from row 2 to 7 includes 4 Beryllium, 12 Magnesium, 20 Calcium, 38 Strontium, 56 Barium, and 88 Radium. Columns 3 to 12 from rows 4 to 7. Column 3 includes 21 Scandium and 39 Yttrium. Column 4 includes 22 Titanium, 40 Zirconium, 72 Hafnium, and 104 Rutherfordium. Column 5 includes 23 Vanadium, 41 Niobium, 73 Tantalum, and 105 Dubnium. Column 6 includes 24 Chromium, 42 Molybdenum, 74 Tungsten, and 106 Seaborgium. Column 7 includes 25 Manganese, 43 Technetium, 75 Rhenium, and 107 Bohrium. Column 8 includes 26 Iron, 44 Ruthenium, 76 Osmium, and 108 Hassium. Column 9 includes 27 Cobalt, 45 Rhodium, 77 Iridium, and 109 Meitnerium. Column 10 includes 28 Nickel, 46 Palladium, 78 Platinum, and 110 Darmstadtium. Column 11 includes 29 Copper, 47 Silver, 79 Gold, and 111 Roentgenium. Column 12 includes 30 Zinc, 48 Cadmium, 80 Mercury, and 112 Copernicium. Column 13 to 17 from rows 2 to 7. Column 13 includes 5 Boron, 13 Aluminum, 31 Gallium, 49 Indium, 81 Thallium, and 113 Nihonium. Column 14 includes 6 Carbon, 14 Silicon, 32 Germanium, 50 Tin, 82 Lead, and 114 Flerovium. Column 15 includes 7 Nitrogen, 15 Phosphorous, 33 Arsenic, 51 Antimony, 83 Bismuth, and 115 Moscovium. Column 16 includes 8 Oxygen, 16 Sulfur, 34 Selenium, 52 Tellurium, 84 Polonium, and 116 Livermorium. Column 17 includes 9 Fluorine, 17 Chlorine, 35 Bromine, 53 Iodine, 85 Astatine, and 117 Tennessine. The last column, column 18, from row 1 to 7 includes 2 Helium, 10 Neon, 18 Argon, 36 Krypton, 54 Xeon, 86 Radon, and 118 Oganesson. Lanthanides and actinides are extra rows at bottom.

Figure 1: Periodic Table