1 Hydrogène H 1,00794 2 Hélium He 4,002602 3 Lithium Li 6,941 4 Béryllium Be 9,012182 5 Bore B 10,811 6 Carbone C 12,011 7 Azote N 14,00674 8 Oxygène O 15,9994 9 Fluor F 18,9984032 10 Néon Ne 20,1797 11 Sodium Na 22,989768 12 Magnésium Mg 24,305 13 Aluminium Al 26,981539 14 Silicium Si 28,0855 15 Phosphore P 30,973762 16 Soufre S 32,066 17 Chlore Cl 35,4527 18 Argon Ar 39,948 19 Potassium K 39,0983 20 Calcium Ca 40,078 21 Scandium Sc 44,95591 22 Titane Ti 47,88 23 Vanadium V 50,9415 24 Chrome Cr 51,9961 25 Manganèse Mn 54,93805 26 Fer Fe 55,847 27 Cobalt Co 58,9332 28 Nickel Ni 58,69 29 Cuivre Cu 63,546 30 Zinc Zn 65,39 31 Gallium Ga 69,723 32 Germanium Ge 72,61 33 Arsenic As 74,92159 34 Sélénium Se 78,96 35 Brome Br 79,904 36 Krypton Kr 83,8 37 Rubidium Rb 85,4678 38 Strontium Sr 87,62 39 Yttrium Y 88,90585 40 Zirconium Zr 91,224 41 Niobium Nb 92,90638 42 Molybdène Mo 95,94 43 Technétium Tc 98,9063 44 Ruthénium Ru 101,07 45 Rhodium Rh 102,9055 46 Palladium Pd 106,42 47 Argent Ag 107,8682 48 Cadmium Cd 112,411 49 Indium In 114,82 50 Étain Sn 118,71 51 Antimoine Sb 121,75 52 Tellure Te 127,6 53 Iode I 126,90447 54 Xénon Xe 131,29 55 Césium Cs 132,90543 56 Baryum Ba 137,327 57 Lanthane La 138,9055 58 Cérium Ce 140,115 59 Praséodyme Pr 140,90765 60 Néodyme Nd 144,24 61 Prométhium Pm 146,9151 62 Samarium Sm 150,36 63 Europium Eu 151,965 64 Gadolinium Gd 157,25 65 Terbium Tb 158,92534 66 Dysprosium Dy 162,5 67 Holmium Ho 164,93032 68 Erbium Er 167,26 69 Thulium Tm 168,93421 70 Ytterbium Yb 173,04 71 Lutécium Lu 174,967 72 Hafnium Hf 178,49 73 Tantale Ta 180,9479 74 Tungstène W 183,85 75 Rhénium Re 186,207 76 Osmium Os 190,2 77 Iridium Ir 192,22 78 Platine Pt 195,08 79 Or Au 196,96654 80 Mercure Hg 200,59 81 Thallium Tl 204,3833 82 Plomb Pb 207,2 83 Bismuth Bi 208,98037 84 Polonium Po 208,9824 85 Astate At 209,9871 86 Radon Rn 222,0176 87 Francium Fr 223,0197 88 Radium Ra 226,0254 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 Américium Am 243,0614 96 Curium Cm 247,0703 97 Berkélium Bk 247,0703 98 Californium Cf 251,0796 99 Einsteinium Es 252,0829 100 Fermium Fm 257,0951 101 Mendélévium Md 258,0986 102 Nobélium No 259,1009 103 Lawrencium Lr 260,1053 104 Rutherfordium Rf 261,1087 105 Dubnium Db 262,1138 106 Seaborgium Sg 263,1182 107 Bohrium Bh 262,1229 108 Hassium Hs 265 109 Meitnerium Mt 266 110 Darmstadtium Ds 269 111 Rœntgenium Rg 272 112 Copernicium Cn 277 113 Ununtrium Uut 114 Ununquadium Uuq 115 Ununpentium Uup 116 Ununhexium Uuh 117 Ununseptium Uus 118 Ununoctium Uuo