Page 2 - Water and Wastewater Engineering Design Principles and Practice

List of the elements with their symbols and atomic masses*

Atomic Atomic Atomic Atomic
Element Symbol Number Mass† Element Symbol Number Mass†
Actinium Ac 89 (227) Mendelevium Md 101 (258)
Aluminum Al 13 26.98 Mercury Hg 80 200.6
Americium Am 95 (243) Molybdenum Mo 42 95.94
Antimony Sb 51 121.8 Neodymium Nd 60 144.2
Argon Ar 18 39.95 Neon Ne 10 20.18
Arsenic As 33 74.92 Neptunium Np 93 (237)
Astatine At 85 (210) Nickel Ni 28 58.69
Barium Ba 56 137.3 Niobium Nb 41 92.91
Berkelium Bk 97 (247) Nitrogen N 7 14.01
Beryllium Be 4 9.012 Nobelium No 102 (259)
Bismuth Bi 83 209.0 Osmium Os 76 190.2
Bohrium Bh 107 (262) Oxygen O 8 16.00
Boron B 5 10.81 Palladium Pd 46 106.4
Bromine Br 35 79.90 Phosphorus P 15 30.97
Cadmium Cd 48 112.4 Platinum Pt 78 195.1
Calcium Ca 20 40.08 Plutonium Pu 94 (244)
Californium Cf 98 (251) Polonium Po 84 (209)
Carbon C 6 12.01 Potassium K 19 39.10
Cerium Ce 58 140.1 Praseodymium Pr 59 140.9
Cesium Cs 55 132.9 Promethium Pm 61 (145)
Chlorine Cl 17 35.45 Protactinium Pa 91 (231)
Chromium Cr 24 52.00 Radium Ra 88 (226)
Cobalt Co 27 58.93 Radon Rn 86 (222)
Copper Cu 29 63.55 Rhenium Re 75 186.2
Curium Cm 96 (247) Rhodium Rh 45 102.9
Dubnium Db 105 (262) Rubidium Rb 37 85.47
Dysprosium Dy 66 162.5 Ruthenium Ru 44 101.1
Einsteinium Es 99 (252) Rutherfordium Rf 104 (261)
Erbium Er 68 167.3 Samarium Sm 62 150.4
Europium Eu 63 152.0 Scandium Sc 21 44.96
Fermium Fm 100 (257) Seaborgium Sg 106 (266)
Fluorine F 9 19.00 Selenium Se 34 78.96
Francium Fr 87 (223) Silicon Si 14 28.09
Gadolinium Gd 64 157.3 Silver Ag 47 107.9
Gallium Ga 31 69.72 Sodium Na 11 22.99
Germanium Ge 32 72.64 Strontium Sr 38 87.62
Gold Au 79 197.0 Sulfur S 16 32.07
Hafnium Hf 72 178.5 Tantalum Ta 73 180.9
Hassium Hs 108 (277) Technetium Tc 43 (98)
Helium He 2 4.003 Tellurium Te 52 127.6
Holmium Ho 67 164.9 Terbium Tb 65 158.9
Hydrogen H 1 1.008 Thallium Tl 81 204.4
Indium In 49 114.8 Thorium Th 90 232.0
Iodine I 53 126.9 Thulium Tm 69 168.9
Iridium Ir 77 192.2 Tin Sn 50 118.7
Iron Fe 26 55.85 Titanium Ti 22 47.88
Krypton Kr 36 83.80 Tungsten W 74 183.9
Lanthanum La 57 138.9 Uranium U 92 238.0
Lawrencium Lr 103 (262) Vanadium V 23 50.94
Lead Pb 82 207.2 Xenon Xe 54 131.3
Lithium Li 3 6.941 Ytterbium Yb 70 173.0
Lutetium Lu 71 175.0 Yttrium Y 39 88.91
Magnesium Mg 12 24.31 Zinc Zn 30 65.41
Manganese Mn 25 54.94 Zirconium Zr 40 91.22
Meitnerium Mt 109 (268)
*All atomic masses have four significant figures. These values are recommended by the Committee on Teaching of Chemistry, International Union of Pure and
Applied Chemistry.
†Approximate values of atomic masses for radioactive elements are given in parentheses.
Source: Chang, R. Chemistry, 7th ed. Copyright © 2002 The McGraw-Hill Companies, Inc. New York. Reproduced with permission.