Atomic Atomic Number Element Symbol Weight 1 Hydrogen H 1.0079 2 Helium He 4.00260 3 Lithium Li 6.941 4 Beryllium Be 9.01218 5 Boron B 10.81 6 Carbon C 12.011 7 Nitrogen N 14.0067 8 Oxygen O 15.9994 9 Fluorine F 18.9984 10 Neon Ne 20.179 11 Sodium Na 22.9898 12 Magnesium Mg 24.305 13 Aluminum Al 26.9815 14 Silicon Si 28.0855 15 Phosphorus P 30.9738 16 Sulfur S 32.06 17 Chlorine Cl 35.453 18 Argon Ar 39.948 19 Potassium K 39.0983 20 Calcium Ca 40.078 21 Scandium Sc 44.9579 22 Titanium Ti 47.88 23 Vanadium V 50.9415 24 Chromium Cr 51.996 25 Manganese Mn 54.9380 26 Iron Fe 55.847 27 Cobalt Co 58.9332 28 Nickel Ni 58.69 29 Copper Cu 63.546 30 Zinc Zn 65.38 31 Gallium Ga 69.72 32 Germanium Ge 72.59 33 Arsenic As 74.9216 34 Selenium Se 78.96 35 Bromine Br 79.904 36 Krypton Kr 83.80 37 Rubidium Rb 85.4678 38 Strontium Sr 87.62 39 Yttrium Y 88.9059 40 Zirconium Zr 91.22 41 Niobium Nb 92.9064 42 Molybdenum Mo 95.94 43 Technetium Tc 97.9072 44 Ruthenium Ru 101.07 45 Rhodium Rh 102.9055 46 Palladium Pd 106.42 47 Silver Ag 107.8682 48 Cadmium Cd 112.41 49 Indium In 114.82 50 Tin Sn 118.69 51 Antimony Sb 121.79 52 Tellurium Te 127.60 53 Iodine I 126.9045 54 Xenon Xe 131.29 55 Cesium Cs 132.9054 56 Barium Ba 137.33 Start Lanthanide Series 57 Lanthanum La 138.9055 58 Cerium Ce 140.12 59 Praseodymium Pr 140.9077 60 Neodymium Nd 144.24 61 Promethium Pm 144.9127 62 Samarium Sm 150.36 63 Europium Eu 151.96 64 Gadolinium Gd 157.27 65 Terbium Tb 158.9254 66 Dysprosium Dy 162.50 67 Holmium Ho 164.9304 68 Erbium Er 167.26 69 Thulium Tm 168.9342 70 Ytterbium Yb 172.04 71 Lutetium Lu 174.967 End Lanthaniae Series 72 Hafnium Hf 178.49 73 Tantalum Ta 180.9479 74 Tungsten W 183.85 75 Rhenium Re 186.207 76 Osmium Os 190.2 77 Iridium Ir 192.22 78 Platinum Pt 195.08 79 Gold Au 196.9665 80 Mercury Hg 200.59 81 Thallium Tl 204.383 82 Lead Pb 207.2 83 Bismuth Bi 208.9804 84 Polonium Po 208.9824 85 Astatine At 209.9871 86 Radon Rn 222.0176 87 Francium Fr 223.0197 88 Radium Ra 226.0254 Start Actinide Series 89 Actinium Ac 227.0278 90 Thorium Th 232.0381 91 Protactinium Pa 231.0359 92 Uranium U 238.0289 93 Neptunium Np 237.0482 94 Plutonium Pu 244.0642 95 Americium Am 243.0614 96 Curium Cm 247.0703 97 Berkelium Bk 247.0703 98 Californium Cf 251.0796 99 Einsteinium Es 252.083 100 Fermium Fm 257.0951 101 Mendelevium Md 258.10 102 Nobelium No 259.1009 103 Lawrencium Lr 262.11 End Actinide Series 104 Unnilquadium Unq 261.11 (Rutherfodium) (Rf)* 105 Unnilpentium Unp 262.114 (Dubnium) (Db)* 106 Unnilhexium Unh 263.118 (Seaborgium) (Sg)* 107 Unnilseptium Uns 262.12 (Bohrium) (Bh)* 108 Unniloctium Uno ? (Hassium) (Hs)* 109 Unnilennium Une ? (Meitnerium) (Mt)* 110 (unnamed)** ? 111 (unnamed)*** ? 112 (unnamed)*** 277 113 (under construction)*** 114 (under construction)***