Cl Chlorine I 35.5 Br Bromine I 80 I Iodine I 127 F Fluorine I 29 P Phosphorus V 31 S Sulphur VI 32 Si Silicon IV 28 B Boron III 11 Se Selenium VI 79.5 Te Tellurium VI 179 Mechanics, arts, science, and medicine. Al Aluminium IV 27.4 Ca Calcium II 40 (Cuprum) Cu Copper II 63.5 (Ferrum) Fe Iron IV 56 (Plumbum) Pb Lead IV 207 Mn Manganese IV 55 (Hydrargyrum) Hg Mercury II 200 (Kalium) K Potassium I 39.1 (Argentum) Ag Silver I 108 (Natrium) Na Sodium I 23 (Stannum) Sn Tin IV 118 Zn Zinc II 65.3 (Stibium) Sb Antimony V 122 As Arsenic V 75 Ba Barium II 137 Bi Bismuth V 210 Cr Chromium VI 52.2 Co Cobalt IV 58.7 (Aurum) Au Gold III 197 In Indium IV 74 Mg Magnesium II 24 Ni Nickel IV 58.7 Pd [2] Palladium IV 106.6 Pt Platinum IV 197.5 Sr Strontium II 87.5 Ti Titanium IV 50 W Tungsten VI 184 U Uranium IV 120 Little known, rarely used.