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APPENDIX

Atomic Masses

T

he masses of neutral atoms of all stable and some unstable nuclides are given

here together with the relative abundances of nuclides found in nature and the

half-lives of the listed radionuclides. Many other radionuclides are known.

Atomic Relative

Z Element Symbol A Mass, u Abundance, % Half-Life

0 Neutron n 1 1.008 665 10.6 min

1 Hydrogen H 1 1.007 825 99.985

2 2.014 102 0.015

3 3.016 050 12.3 y

2 Helium He 3 3.016 029 0.0001

4 4.002 603 99.9999

6 6.018 891 805 ms

3 Lithium Li 6 6.015 123 7.5

7 7.016 004 92.5

8 8.022 487 844 ms

4 Beryllium Be 7 7.016 930 53.3 d

8 8.005 305 6.7 10 ^17 s

9 9.012 182 100

10 10.013 535 1.6  106 y

5 Boron B 10 10.012 938 20

11 11.009 305 80

12 12.014 353 20.4 ms

6 Carbon C 10 10.016 858 19.3 s

11 11.011 433 20.3 min

12 12.000 000 98.89

13 13.003 355 1.11

14 14.003 242 5760 y

15 15.010 599 2.45 s

7 Nitrogen N 12 12.018 613 11.0 ms

13 13.005 739 9.97 min

14 14.003 074 99.63

15 15.000 109 0.37

16 16.006 099 7.10 s

17 17.008 449 4.17 s

8 Oxygen O 14 14.008 597 70.5 s

15 15.003 065 122 s

16 15.994 915 99.758

17 16.999 131 0.038

18 17.999 159 0.204

19 19.003 576 26.8 s

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