Periodic Elements 1 12C the At No 18 Symbol = 12.0000 He Name Values are quoted to significant figures, or as many as R.A.M are reliable A value in brackets refers to the most stable isotope Hydrogen 1.008 of Relative Atomic Masses based on University of St Andrews H Table Helium 13 14 15 16 17 4.0026 10 Ne Li Be B C N O F Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon 6.94 11 9.0122 12 10.81 13 12.011 14 14.007 15 15.999 16 18.998 17 20.180 18 Ar Na Mg Sodium Magnesium 22.990 19 24.305 20 Al Si P S Cl Aluminium Silicon Phosphorus Sulfur Chlorine Argon 28.085 32 30.974 33 32.06 34 35.45 35 39.948 36 10 11 12 21 22 23 24 25 26 27 28 29 30 26.982 31 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton 39.098 37 40.078 38 44.956 39 47.867 40 50.942 41 51.996 42 54.938 43 55.845 44 58.933 45 58.693 46 63.546 47 65.38 48 69.723 49 72.63 50 74.922 51 78.96 52 79.904 53 83.798 54 Xe Rb Sr Y Zr Tc Ru Rh Pd Ag Cd In Sn Sb Te I Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon 85.468 55 87.62 56 88.906 57-71 91.224 72 92.906 73 95.96 74 (98) 75 101.07 76 102.91 77 106.42 78 107.87 79 112.41 80 114.82 81 118.71 82 121.76 83 127.60 84 126.90 85 131.29 86 Cs Ba Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Caesium Barium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury Thallium Lead Bismuth Polonium Astatine Radon 132.91 87 137.33 88 89-103 178.49 104 180.95 105 183.84 106 186.21 107 190.23 108 192.22 109 195.08 110 196.97 111 200.59 112 204.38 113 207.2 114 208.98 115 (209) 116 (210) 117 (222) 118 Fr Ra see Actinides Rf Db Sg Bh Hs Mt Ds Rg Francium Radium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium (223) (226) (265) (268) (271) (270) (277) (276) see Lanthanides Lanthanoids Nb Mo 57 58 59 60 61 62 Darmstadtium Roentgenium (281) 63 Nd Pm Sm Eu Cn Nh Fl Mc Lv Ts Og Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson (285) (284) (289) (288) (293) (294) (294) (280) 64 65 66 67 68 69 70 Tm Yb 71 La Ce Pr Gd Tb Dy Ho Er Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Lu 138.91 140.12 140.91 144.24 (145) 150.36 151.96 157.25 158.93 162.50 164.93 167.26 168.93 173.05 174.97 Actinoids 89 90 91 92 93 94 95 96 97 Ac Th Pa U Np Cf Es Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium (227) 232.04 231.04 238.03 (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) (262) Pu Am Cm Bk 98 99 100 101 102 Fm Md No 103 Lr