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Current atomic masses

Atomic masses of isotopes are evaluated by IUPAP and below is the latest Atomic Mass Evaluation report, dated 2012. All atomic masses of nuclides, ma, are expressed in daltons (symbol Da), which is 1/12 mass of a single carbon-12 atom (unbound, neutral, in its electronic and nuclear ground state, and at rest).

Atomic Masses used by CIAAW (2012)

Z Symbol Element A Atomic mass,
ma/Da
1 H hydrogen 1   1.007 825 0322(6)
2   2.014 101 7781(8)
2 He helium 3   3.016 029 32(2)
4   4.002 603 2541(4)
3 Li lithium 6   6.015 122 887(9)
7   7.016 003 44(3)
4 Be beryllium 9   9.012 1831(5)
5 B boron 10  10.012 937(3)
11  11.009 305(3)
6 C carbon 12  12(exactly)
13  13.003 354 835(2)
7 N nitrogen 14  14.003 074 004(2)
15  15.000 108 899(4)
8 O oxygen 16  15.994 914 620(2)
17  16.999 131 757(5)
18  17.999 159 613(6)
9 F fluorine 19  18.998 403 163(6)
10 Ne neon 20  19.992 440 18(2)
21  20.993 8467(3)
22  21.991 3851(2)
11 Na sodium 23  22.989 769 28(2)
12 Mg magnesium 24  23.985 041 70(9)
25  24.985 8370(3)
26  25.982 5930(2)
13 Al aluminium 27  26.981 5385(7)
14 Si silicon 28  27.976 926 535(3)
29  28.976 494 665(3)
30  29.973 770 01(2)
15 P phosphorous 31  30.973 761 998(5)
16 S sulfur 32  31.972 071 174(9)
33  32.971 458 910(9)
34  33.967 8670(3)
36  35.967 081(2)
17 Cl chlorine 35  34.968 8527(3)
37  36.965 9026(4)
18 Ar argon 36  35.967 5451(2)
38  37.962 732(2)
40  39.962 383 12(2)
19 K potassium 39  38.963 706 49(3)
40*  39.963 9982(4)
41  40.961 825 26(3)
20 Ca calcium 40  39.962 5909(2)
42  41.958 618(1)
43  42.958 766(2)
44  43.955 482(2)
46  45.953 69(2)
48*  47.952 5228(8)
21 Sc scandium 45  44.955 908(5)
22 Ti titanium 46  45.952 628(3)
47  46.951 759(3)
48  47.947 942(3)
49  48.947 866(3)
50  49.944 787(3)
23 V vanadium 50*  49.947 156(6)
51  50.943 957(6)
24 Cr chromium 50  49.946 042(6)
52  51.940 506(4)
53  52.940 648(4)
54  53.938 879(4)
25 Mn manganese 55  54.938 044(3)
26 Fe iron 54  53.939 609(3)
56  55.934 936(3)
57  56.935 393(3)
58  57.933 274(3)
27 Co cobalt 59  58.933 194(4)
28 Ni nickel 58  57.935 342(3)
60  59.930 786(3)
61  60.931 056(3)
62  61.928 345(4)
64  63.927 967(4)
29 Cu copper 63  62.929 598(4)
65  64.927 790(5)
30 Zn zinc 64  63.929 142(5)
66  65.926 034(6)
67  66.927 128(6)
68  67.924 845(6)
70  69.925 32(2)
31 Ga gallium 69  68.925 574(8)
71  70.924 703(6)
32 Ge germanium 70  69.924 249(6)
72  71.922 0758(5)
73  72.923 4590(4)
74  73.921 177 76(9)
76*  75.921 4027(2)
33 As arsenic 75  74.921 595(6)
34 Se selenium 74  73.922 4759(1)
76  75.919 2137(2)
77  76.919 9142(5)
78  77.917 309(2)
80  79.916 522(8)
82*  81.916 700(9)
35 Br bromine 79  78.918 338(9)
81  80.916 290(9)
36 Kr krypton 78*  77.920 365(5)
80  79.916 378(5)
82  81.913 483(6)
83  82.914 127(2)
84  83.911 497 73(3)
86  85.910 610 63(3)
37 Rb rubidium 85  84.911 789 74(3)
87*  86.909 180 53(5)
38 Sr strontium 84  83.913 419(8)
86  85.909 261(8)
87  86.908 878(8)
88  87.905 613(8)
39 Y yttrium 89  88.905 84(2)
40 Zr zirconium 90  89.904 70(2)
91  90.905 64(2)
92  91.905 03(2)
94  93.906 31(2)
96*  95.908 27(2)
41 Nb niobium 93  92.906 37(2)
42 Mo molybdenum 92  91.906 808(5)
94  93.905 085(3)
95  94.905 839(3)
96  95.904 676(3)
97  96.906 018(3)
98  97.905 405(3)
100*  99.907 472(7)
43 Tc technetium 98*  97.907 21(3)
44 Ru ruthenium 96  95.907 590(3)
98  97.905 29(5)
99  98.905 934(7)
100  99.904 214(7)
101 100.905 577(8)
102 101.904 344(8)
104 103.905 43(2)
45 Rh rhodium 103 102.905 50(2)
46 Pd palladium 102 101.905 60(2)
104 103.904 031(9)
105 104.905 080(8)
106 105.903 480(8)
108 107.903 892(8)
110 109.905 172(5)
47 Ag silver 107 106.905 09(2)
109 108.904 755(9)
48 Cd cadmium 106 105.906 460(8)
108 107.904 183(8)
110 109.903 007(4)
111 110.904 183(4)
112 111.902 763(4)
113* 112.904 408(3)
114 113.903 365(3)
116* 115.904 763(2)
49 In indium 113 112.904 062(6)
115* 114.903 878 78(8)
50 Sn tin 112 111.904 824(4)
114 113.902 783(6)
115 114.903 3447(1)
116 115.901 743(1)
117 116.902 954(3)
118 117.901 607(3)
119 118.903 311(5)
120 119.902 202(6)
122 121.903 44(2)
124 123.905 277(7)
51 Sb antimony 121 120.903 81(2)
123 122.904 21(2)
52 Te tellurium 120 119.904 06(2)
122 121.903 04(1)
123 122.904 27(1)
124 123.902 82(1)
125 124.904 43(1)
126 125.903 31(1)
128* 127.904 461(6)
130* 129.906 222 75(8)
53 I iodine 127 126.904 47(3)
54 Xe xenon 124 123.905 89(2)
126 125.904 30(3)
128 127.903 531(7)
129 128.904 780 86(4)
130 129.903 5094(1)
131 130.905 084(2)
132 131.904 155 09(4)
134 133.905 395(6)
136* 135.907 214 48(7)
55 Cs caesium 133 132.905 451 96(6)
56 Ba barium 130* 129.906 32(2)
132 131.905 061(7)
134 133.904 508(2)
135 134.905 688(2)
136 135.904 576(2)
137 136.905 827(2)
138 137.905 247(2)
57 La lanthanum 138* 137.907 12(3)
139 138.906 36(2)
58 Ce cerium 136 135.907 129(3)
138 137.905 99(7)
140 139.905 44(2)
142 141.909 25(2)
59 Pr praseodymium 141 140.907 66(2)
60 Nd neodymium 142 141.907 73(2)
143 142.909 82(2)
144* 143.910 09(2)
145 144.912 58(2)
146 145.913 12(2)
148 147.916 90(2)
150* 149.920 90(2)
61 Pm promethium 145* 144.912 76(2)
62 Sm samarium 144 143.912 01(2)
147* 146.914 90(2)
148* 147.914 83(2)
149 148.917 19(2)
150 149.917 28(2)
152 151.919 74(2)
154 153.922 22(2)
63 Eu europium 151* 150.919 86(2)
153 152.921 24(2)
64 Gd gadolinium 152 151.919 80(2)
154 153.920 87(2)
155 154.922 63(2)
156 155.922 13(2)
157 156.923 97(2)
158 157.924 11(2)
160 159.927 06(2)
65 Tb terbium 159 158.925 35(2)
66 Dy dysprosium 156 155.924 28(2)
158 157.924 42(2)
160 159.925 20(2)
161 160.926 94(2)
162 161.926 81(2)
163 162.928 74(2)
164 163.929 18(2)
67 Ho holmium 165 164.930 33(2)
68 Er erbium 162 161.928 79(2)
164 163.929 21(2)
166 165.930 30(2)
167 166.932 05(2)
168 167.932 38(2)
170 169.935 47(2)
69 Tm thulium 169 168.934 22(2)
70 Yb ytterbium 168 167.933 89(2)
170 169.934 77(2)
171 170.936 33(2)
172 171.936 39(2)
173 172.938 22(2)
174 173.938 87(2)
176 175.942 58(2)
71 Lu lutetium 175 174.940 78(2)
176* 175.942 69(2)
72 Hf hafnium 174* 173.940 05(2)
176 175.941 41(2)
177 176.943 23(2)
178 177.943 71(2)
179 178.945 82(2)
180 179.946 56(2)
73 Ta tantalum 180* 179.947 46(2)
181 180.948 00(2)
74 W tungsten 180* 179.946 71(2)
182 181.948 204(6)
183 182.950 223(6)
184 183.950 931(6)
186 185.954 36(2)
75 Re rhenium 185 184.952 955(8)
187* 186.955 75(1)
76 Os osmium 184* 183.952 489(9)
186* 185.953 84(1)
187 186.955 75(1)
188 187.955 84(1)
189 188.958 14(2)
190 189.958 44(2)
192 191.961 48(2)
77 Ir iridium 191 190.960 59(2)
193 192.962 92(2)
78 Pt platinum 190* 189.959 93(4)
192 191.961 04(2)
194 193.962 681(6)
195 194.964 792(6)
196 195.964 952(6)
198 197.967 89(2)
79 Au gold 197 196.966 569(5)
80 Hg mercury 196 195.965 83(2)
198 197.966 769(3)
199 198.968 281(3)
200 199.968 327(3)
201 200.970 303(5)
202 201.970 643(5)
204 203.973 494(3)
81 Tl thallium 203 202.972 345(9)
205 204.974 428(9)
82 Pb lead 204 203.973 044(8)
206 205.974 466(8)
207 206.975 897(8)
208 207.976 653(8)
83 Bi bismuth 209* 208.980 40(1)
90 Th thorium 230* 230.033 13(2)
232* 232.038 06(2)
91 Pa protactinium 231* 231.035 88(2)
92 U uranium 233* 233.039 64(2)
234* 234.040 95(2)
235* 235.043 93(2)
238* 238.050 79(2)
Z Symbol Element A Atomic mass,
ma/Da

Footnote      Back to Top
Radioactive isotope.

CIAAW uses nuclide masses as reported in the Atomic Mass Evaluation reports. However, the uncertainty of the nuclide masses is not taken as reported. Rather, all uncertainty estimates are expanded by a factor of k = 6 in order to conform to the conservative reporting practices of CIAAW.

Adapted from

M. Wang et al
The Ame2012 Atomic Mass Evaluation Chinese Physics C, 2012 (36) 1603-2014

CIAAW uses nuclide masses as reported in the Atomic Mass Evaluation reports. However, the uncertainty of the nuclide masses is not taken as reported. Rather, all uncertainty estimates are expanded by a factor of k = 6 in order to conform to the conservative reporting practices of CIAAW.