Atomic weights shown in this table are 1977 values.
For long-lived isotope of an element that has no stable isotopes, standard atomic weights cannot be defined because of wide variaty of isotopic composition in nature.
For these elements, refer to "Atomic masses and abundances" table in ther following references.

- D.R.Linde ed., "CRC handbook of Chemistry and Physics", 76th ed., CRC Press, Boca Raton (1995)
- IUPAC Commission on Atomic Weights and Isotopic Abundances, Pure Appl. Chem., 63, 991 (1991)


Atom No. Group Name Symbol Atom.Wt. (g/mol)
1 1A Hydrogen H 1.0079
2 0 Helium He 4.0026
3 1A Lithium Li 6.941
4 2A Beryllium Be 9.01218
5 3A Boron B 10.81
6 4A Carbon C 12.011
7 5A Nitrogen N 14.0067
8 6A Oxygen O 15.9994
9 7A Fluorine F 18.9984
10 0 Neon Ne 20.179
11 1A Sodium Na 22.98977
12 2A Magnesium Mg 24.305
13 3A Aluminium Al 26.98154
14 4A Silicon Si 28.0855
15 5A Phosphorus P 30.97376
16 6A Sulfur S 32.06
17 7A Chlorine Cl 35.453
18 0 Argon Ar 39.948
19 1A Potassium K 39.0983
20 2A Calcium Ca 40.08
21 3B Scandium Sc 44.9559
22 4B Titanium Ti 47.88
23 5B Vanadium V 50.9415
24 6B Chromium Cr 51.996
25 7B Manganese Mn 54.938
26 8 Iron Fe 55.847
27 8 Cobalt Co 58.9332
28 8 Nickel Ni 58.69
29 1B Copper Cu 63.546
30 2B Zinc Zn 65.38
31 3A Gallium Ga 69.72
32 4A Germanium Ge 72.59
33 5A Arsenic As 74.9216
34 6A Selenium Se 78.96
35 7A Bromine Br 79.904
36 0 Krypton Kr 83.8
37 1A Rubidium Rb 85.4678
38 2A Strontium Sr 87.62
39 3B Yttrium Y 88.9059
40 4B Zirconium Zr 91.22
41 5B Niobium Nb 92.9064
42 6B Molybdenum Mo 95.94
43 7B Technetium Tc 98
44 8 Ruthenium Ru 101.07
45 8 Rhodium Rh 102.9055
46 8 Palladium Pd 106.42
47 1B Silver Ag 107.8682
48 2B Cadmium Cd 112.41
49 3A Indium In 114.82
50 4A Tin Sn 118.69
51 5A Antimony Sb 121.75
52 6A Tellurium Te 127.6
53 7A Iodine I 126.9045
54 0 Xenon Xe 131.29
55 1A Caesium Cs 132.9054
56 2A Barium Ba 137.33
57 3B Lanthanum La 138.9055
58 LANTH Cerium Ce 140.12
59 LANTH Praseodymium Pr 140.9077
60 LANTH Neodymium Nd 144.24
61 LANTH Promethium Pm 145
62 LANTH Samarium Sm 150.36
63 LANTH Europium Eu 151.96
64 LANTH Gadolinium Gd 157.25
65 LANTH Terbium Tb 158.9254
66 LANTH Dysprosium Dy 160.5
67 LANTH Holmium Ho 164.9304
68 LANTH Erbium Er 167.26
69 LANTH Thulium Tm 168.9342
70 LANTH Ytterbium Yb 173.04
71 LANTH Lutetium Lu 174.967
72 4B Hafnium Hf 178.49
73 5B Tantalum Ta 180.9479
74 6B Tungsten W 183.85
75 7B Rhenium Re 186.207
76 8 Osmium Os 190.2
77 8 Iridium Ir 192.22
78 8 Platinum Pt 195.08
79 1B Gold Au 196.9665
80 2B Mercury Hg 200.59
81 3A Thallium Tl 204.383
82 4A Lead Pb 207.2
83 5A Bismuth Bi 208.9804
84 6A Polonium Po 209
85 7A Astatine At 210
86 0 Radon Rn 222
87 1A Francium Fr 223
88 2A Radium Ra 226.0254
89 3B Actinium Ac 227.0278
90 ACTIN Thorium Th 232.0381
91 ACTIN Protactinium Pa 231.0359
92 ACTIN Uranium U 238.0289
93 ACTIN Neptunium Np 237.0482
94 ACTIN Plutonium Pu 244.0642
95 ACTIN Americium Am 243.0614
96 ACTIN Curium Cm 247.0703
97 ACTIN Berkelium Bk 247.0703
98 ACTIN Californium Cf 251.0796
99 ACTIN Einsteinium Es 252.0829
100 ACTIN Fermium Fm 257.0951
101 ACTIN Mendelevium Md 258.0986
102 CATIN Nobelium No 259.1009
103 ACTIN Lawrencium Lr 260.1053
104 4B Rutherfordium Rf 261.1087
105 5B Hahnium Ha 262.1138
106 6B Seaborgium Sg 263.1182
107 7B Nielsbohrium Ns 262.1229
108 8B Hassium Hs 265
109 9B Meitnerium Mt 266