Published on Texas Gateway (https://texasgateway.org)
<span class="os-number">A</span><span class="os-divider"> | </span><span class="os-text">Atomic Masses</span>

A | Atomic Masses

Atomic Number, Z Name Atomic Mass Number, A Symbol Atomic Mass (u) Percent Abundance or Decay Mode Half-life, t1/2
0 neutron 1 n n size 12{n} {} 1.008 665 β − β − size 12{β rSup { size 8{ - {}} } } {} 10.37 min
1 Hydrogen 1 1 H 1 H size 12{rSup { size 8{ 1 {}} }H} {} 1.007 825 99.985%
Deuterium 2 2 H or D 2 H or D size 12{rSup { size 8{ 2 {}} }H or D} {} 2.014 102 0.015%
Tritium 3 3 H or T 3 H or T size 12{rSup { size 8{ 3 {}} }H or T} {} 3.016 050 β − β − size 12{β rSup { size 8{ - {}} } } {} 12.33 y
2 Helium 3 3 He 3 He size 12{rSup { size 8{ 3 {}} }He} {} 3.016 030 1 . 38 × 10 − 4 % 1 . 38 × 10 − 4 % size 12{1 "." "38" times "10" rSup { size 8{ - 4} } %} {}
4 4 He 4 He size 12{rSup { size 8{ 4 {}} }He} {} 4.002 603 ≈100% ≈100% size 12{ approx "100"%} {}
3 Lithium 6 6 Li 6 Li size 12{rSup { size 8{ 6 {}} }Li} {} 6.015 121 7.5%
7 7 Li 7 Li size 12{rSup { size 8{ 7 {}} }Li} {} 7.016 003 92.5%
4 Beryllium 7 7 Be 7 Be size 12{rSup { size 8{ 7 {}} }Be} {} 7.016 928 EC 53.29 d
9 9 Be 9 Be size 12{rSup { size 8{ 9 {}} }Be} {} 9.012 182 100%
5 Boron 10 10 B 10 B size 12{rSup { size 8{ 10 {}} }B} {} 10.012 937 19.9%
11 11 B 11 B size 12{rSup { size 8{ 11 {}} }B} {} 11.009 305 80.1%
6 Carbon 11 11 C 11 C size 12{rSup { size 8{ 11 {}} }C} {} 11.011 432 EC, β + β + size 12{β rSup { size 8{+{}} } } {}
12 12 C 12 C size 12{rSup { size 8{ 6 {}} }Li} {} 12.000 000 98.90%
13 13 C 13 C size 12{rSup { size 8{ 13 {}} }C} {} 13.003 355 1.10%
14 14 C 14 C size 12{rSup { size 8{ 14 {}} }C} {} 14.003 241 β − β − size 12{β rSup { size 8{ - {}} } } {} 5730 y
7 Nitrogen 13 13 N 13 N size 12{rSup { size 8{ 13 {}} }N} {} 13.005 738 β + β + size 12{β rSup { size 8{+{}} } } {} 9.96 min
14 14 N 14 N size 12{rSup { size 8{ 14 {}} }N} {} 14.003 074 99.63%
15 15 N 15 N size 12{rSup { size 8{ 15 {}} }N} {} 15.000 108 0.37%
8 Oxygen 15 15 O 15 O size 12{rSup { size 8{ 15 {}} }O} {} 15.003 065 EC, β + β + size 12{β rSup { size 8{+{}} } } {} 122 s
16 16 O 16 O size 12{rSup { size 8{ 6 {}} }Li} {} 15.994 915 99.76%
18 18 O 18 O size 12{rSup { size 8{ 18 {}} }O} {} 17.999 160 0.200%
9 Fluorine 18 18 F 18 F size 12{rSup { size 8{ 18 {}} }F} {} 18.000 937 EC, β + β + size 12{β rSup { size 8{+{}} } } {} 1.83 h
19 19 F 19 F size 12{rSup { size 8{ 6 {}} }Li} {} 18.998 403 100%
10 Neon 20 20 Ne 20 Ne size 12{rSup { size 8{ 20 {}} }Ne} {} 19.992 435 90.51%
22 22 Ne 22 Ne size 12{rSup { size 8{ 22 {}} }Ne} {} 21.991 383 9.22%
11 Sodium 22 22 Na 22 Na size 12{rSup { size 8{ 6 {}} }Li} {} 21.994 434 β + β + size 12{β rSup { size 8{ - {}} } } {} 2.602 y
23 23 Na 23 Na size 12{rSup { size 8{ 23 {}} }Na} {} 22.989 767 100%
24 24 Na 24 Na size 12{rSup { size 8{ 24 {}} }Na} {} 23.990 961 β − β − size 12{β rSup { size 8{ - {}} } } {} 14.96 h
12 Magnesium 24 24 Mg 24 Mg size 12{rSup { size 8{ 24 {}} }Mg} {} 23.985 042 78.99%
13 Aluminum 27 27 Al 27 Al size 12{rSup { size 8{ 27 {}} }Al} {} 26.981 539 100%
14 Silicon 28 28 Si 28 Si size 12{rSup { size 8{ 28 {}} }Si} {} 27.976 927 92.23% 2.62h
31 31 Si 31 Si size 12{rSup { size 8{ 31 {}} }Si} {} 30.975 362 β − β − size 12{β rSup { size 8{ - {}} } } {}
15 Phosphorus 31 31 P 31 P size 12{rSup { size 8{ 31 {}} }P} {} 30.973 762 100%
32 32 P 32 P size 12{rSup { size 8{ 6 {}} }Li} {} 31.973 907 β − β − size 12{β rSup { size 8{ - {}} } } {} 14.28 d
16 Sulfur 32 32 S 32 S size 12{rSup { size 8{ 6 {}} }Li} {} 31.972 070 95.02%
35 35 S 35 S size 12{rSup { size 8{ 35 {}} }S} {} 34.969 031 β − β − size 12{β rSup { size 8{ - {}} } } {} 87.4 d
17 Chlorine 35 35 Cl 35 Cl size 12{rSup { size 8{ 35 {}} }Cl} {} 34.968 852 75.77%
37 37 Cl 37 Cl size 12{rSup { size 8{ 35 {}} }Cl} {} 36.965 903 24.23%
18 Argon 40 40 Ar 40 Ar size 12{rSup { size 8{ 40 {}} }Ar} {} 39.962 384 99.60%
19 Potassium 39 39 K 39 K size 12{rSup { size 8{ 39 {}} }K} {} 38.963 707 93.26%
40 40 K 40 K size 12{rSup { size 8{ 40 {}} }K} {} 39.963 999 0.0117%, EC, β−β− size 12{β rSup { size 8{ - {}} } } {} 1 . 28 × 10 9 y 1 . 28 × 10 9 y size 12{1 "." "28" times "10" rSup { size 7{9} } y} {}
20 Calcium 40 40 Ca 40 Ca size 12{rSup { size 8{ 40 {}} }Ca} {} 39.962 591 96.94%
21 Scandium 45 45 Sc 45 Sc size 12{rSup { size 8{ 45 {}} }Sc} {} 44.955 910 100%
22 Titanium 48 48 Ti 48 Ti size 12{rSup { size 8{ 48 {}} }Ti} {} 47.947 947 73.8%
23 Vanadium 51 51 V 51 V size 12{rSup { size 8{ 51 {}} }V} {} 50.943 962 99.75%
24 Chromium 52 52 Cr 52 Cr size 12{rSup { size 8{ 52 {}} }Cr} {} 51.940 509 83.79%
25 Manganese 55 55 Mn 55 Mn size 12{rSup { size 8{ 55 {}} }Mn} {} 54.938 047 100%
26 Iron 56 56 Fe 56 Fe size 12{rSup { size 8{ 56 {}} }Fe} {} 55.934 939 91.72%
27 Cobalt 59 59 Co 59 Co size 12{rSup { size 8{ 59 {}} }Co} {} 58.933 198 100%
60 60 Co 60 Co size 12{rSup { size 8{ 60 {}} }Co} {} 59.933 819 β − β − size 12{β rSup { size 8{ - {}} } } {} 5.271 y
28 Nickel 58 58 Ni 58 Ni size 12{rSup { size 8{ 58 {}} }Ni} {} 57.935 346 68.27%
60 60 Ni 60 Ni size 12{rSup { size 8{ 60 {}} }Ni} {} 59.930 788 26.10%
29 Copper 63 63 Cu 63 Cu size 12{rSup { size 8{ 63 {}} }Cu} {} 62.939 598 69.17%
65 65 Cu 65 Cu size 12{rSup { size 8{ 65 {}} }Cu} {} 64.927 793 30.83%
30 Zinc 64 64 Zn 64 Zn size 12{rSup { size 8{ 64 {}} }Zn} {} 63.929 145 48.6%
66 66 Zn 66 Zn size 12{rSup { size 8{ 66 {}} }Zn} {} 65.926 034 27.9%
31 Gallium 69 69 Ga 69 Ga size 12{rSup { size 8{ 69 {}} }Ga} {} 68.925 580 60.1%
32 Germanium 72 72 Ge 72 Ge size 12{rSup { size 8{ 72 {}} }Ge} {} 71.922 079 27.4%
74 74 Ge 74 Ge size 12{rSup { size 8{ 74 {}} }Ge} {} 73.921 177 36.5%
33 Arsenic 75 75 As 75 As size 12{rSup { size 8{ 75 {}} }As} {} 74.921 594 100%
34 Selenium 80 80 Se 80 Se size 12{rSup { size 8{ 80 {}} }Se} {} 79.916 520 49.7%
35 Bromine 79 79 Br 79 Br size 12{rSup { size 8{ 79 {}} }Br} {} 78.918 336 50.69%
36 Krypton 84 84 Kr 84 Kr size 12{rSup { size 8{ 84 {}} }Kr} {} 83.911 507 57.0%
37 Rubidium 85 85 Rb 85 Rb size 12{rSup { size 8{ 85 {}} }Rb} {} 84.911 794 72.17%
38 Strontium 86 86 Sr 86 Sr size 12{rSup { size 8{ 86 {}} }Sr} {} 85.909 267 9.86%
88 88 Sr 88 Sr size 12{rSup { size 8{ 88 {}} }Sr} {} 87.905 619 82.58%
90 90 Sr 90 Sr size 12{rSup { size 8{ 90 {}} }Sr} {} 89.907 738 β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 28.8 y
39 Yttrium 89 89 Y 89 Y size 12{rSup { size 8{ 89 {}} }Y} {} 88.905 849 100%
90 90 Y 90 Y size 12{rSup { size 8{ 90 {}} }Y} {} 89.907 152 β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 64.1 h
40 Zirconium 90 90 Zr 90 Zr size 12{rSup { size 8{ 90 {}} }Zr} {} 89.904 703 51.45%
41 Niobium 93 93 Nb 93 Nb size 12{rSup { size 8{ 93 {}} }Nb} {} 92.906 377 100%
42 Molybdenum 98 98 Mo 98 Mo size 12{rSup { size 8{ 98 {}} }Mo} {} 97.905 406 24.13%
43 Technetium 98 98 Tc 98 Tc size 12{rSup { size 8{ 98 {}} }Tc} {} 97.907 215 β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 4 . 2 × 10 6 y 4 . 2 × 10 6 y size 12{4 "." 2 times "10" rSup { size 8{6} } y} {}
44 Ruthenium 102 102 Ru 102 Ru size 12{rSup { size 8{ 102 {}} }Ru} {} 101.904 348 31.6%
45 Rhodium 103 103 Rh 103 Rh size 12{rSup { size 8{ 103 {}} }Rh} {} 102.905 500 100%
46 Palladium 106 106 Pd 106 Pd size 12{rSup { size 8{ 106 {}} }Pd} {} 105.903 478 27.33%
47 Silver 107 107 Ag 107 Ag size 12{rSup { size 8{ 107 {}} }Ag} {} 106.905 092 51.84%
109 109 Ag 109 Ag size 12{rSup { size 8{ 109 {}} }Ag} {} 108.904 757 48.16%
48 Cadmium 114 114 Cd 114 Cd size 12{rSup { size 8{ 114 {}} }Cd} {} 113.903 357 28.73%
49 Indium 115 115 In 115 In size 12{rSup { size 8{ 115 {}} }In} {} 114.903 880 95.7%, β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 4 . 4 × 10 14 y 4 . 4 × 10 14 y size 12{4 "." 4 times "10" rSup { size 8{"14"} } y} {}
50 Tin 120 120 Sn 120 Sn size 12{rSup { size 8{ 120 {}} }Sn} {} 119.902 200 32.59%
51 Antimony 121 121 Sb 121 Sb size 12{rSup { size 8{ 121 {}} }Sb} {} 120.903 821 57.3%
52 Tellurium 130 130 Te 130 Te size 12{rSup { size 8{ 130 {}} }Te} {} 129.906 229 33.8%, β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 2 . 5 × 10 21 y 2 . 5 × 10 21 y size 12{2 "." 5 times "10" rSup { size 8{"21"} } y} {}
53 Iodine 127 127 I 127 I size 12{rSup { size 8{ 127 {}} }I} {} 126.904 473 100%
131 131 I 131 I size 12{rSup { size 8{ 131 {}} }I} {} 130.906 114 β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 8.040 d
54 Xenon 132 132 Xe 132 Xe size 12{rSup { size 8{ 132 {}} }Xe} {} 131.904 144 26.9%
136 136 Xe 136 Xe size 12{rSup { size 8{ 136 {}} }Xe} {} 135.907 214 8.9%
55 Cesium 133 133 Cs 133 Cs size 12{rSup { size 8{ 133 {}} }Cs} {} 132.905 429 100%
134 134 Cs 134 Cs size 12{rSup { size 8{ 134 {}} }Cs} {} 133.906 696 EC, β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 2.06 y
56 Barium 137 137 Ba 137 Ba size 12{rSup { size 8{ 137 {}} }Ba} {} 136.905 812 11.23%
138 138 Ba 138 Ba size 12{rSup { size 8{ 138 {}} }Ba} {} 137.905 232 71.70%
57 Lanthanum 139 139 La 139 La size 12{rSup { size 8{ 139 {}} }La} {} 138.906 346 99.91%
58 Cerium 140 140 Ce 140 Ce size 12{rSup { size 8{ 140 {}} }Ce} {} 139.905 433 88.48%
59 Praseodymium 141 141 Pr 141 Pr size 12{rSup { size 8{ 141 {}} }Pr} {} 140.907 647 100%
60 Neodymium 142 142 Nd 142 Nd size 12{rSup { size 8{ 142 {}} }Nd} {} 141.907 719 27.13%
61 Promethium 145 145 Pm 145 Pm size 12{rSup { size 8{ 145 {}} }Pm} {} 144.912 743 EC, αα size 12{α} {} 17.7 y
62 Samarium 152 152 Sm 152 Sm size 12{rSup { size 8{ 152 {}} }Sm} {} 151.919 729 26.7%
63 Europium 153 153 Eu 153 Eu size 12{rSup { size 8{ 153 {}} }Eu} {} 152.921 225 52.2%
64 Gadolinium 158 158 Gd 158 Gd size 12{rSup { size 8{ 158 {}} }Gd} {} 157.924 099 24.84%
65 Terbium 159 159 Tb 159 Tb size 12{rSup { size 8{ 159 {}} }Tb} {} 158.925 342 100%
66 Dysprosium 164 164 Dy 164 Dy size 12{rSup { size 8{ 164 {}} }Dy} {} 163.929 171 28.2%
67 Holmium 165 165 Ho 165 Ho size 12{rSup { size 8{ 165 {}} }Ho} {} 164.930 319 100%
68 Erbium 166 166 Er 166 Er size 12{rSup { size 8{ 166 {}} }Er} {} 165.930 290 33.6%
69 Thulium 169 169 Tm 169 Tm size 12{rSup { size 8{ 169 {}} }Tm} {} 168.934 212 100%
70 Ytterbium 174 174 Yb 174 Yb size 12{rSup { size 8{ 174 {}} }Yb} {} 173.938 859 31.8%
71 Lutecium 175 175 Lu 175 Lu size 12{rSup { size 8{ 174 {}} }Yb} {} 174.940 770 97.41%
72 Hafnium 180 180 Hf 180 Hf size 12{rSup { size 8{ 180 {}} }Hf} {} 179.946 545 35.10%
73 Tantalum 181 181 Ta 181 Ta size 12{rSup { size 8{ 181 {}} }Ta} {} 180.947 992 99.98%
74 Tungsten 184 184 W 184 W size 12{rSup { size 8{ 184 {}} }W} {} 183.950 928 30.67%
75 Rhenium 187 187 Re 187 Re size 12{rSup { size 8{ 187 {}} }Re} {} 186.955 744 62.6%, β−β− size 12{β rSup { size 8{ - {}} } } {} 4 . 6 × 10 10 y 4 . 6 × 10 10 y size 12{4 "." 6 times "10" rSup { size 8{"10"} } y} {}
76 Osmium 191 191 Os 191 Os size 12{rSup { size 8{ 191 {}} }Os} {} 190.960 920 β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 15.4 d
192 192 Os 192 Os size 12{rSup { size 8{ 192 {}} }Os} {} 191.961 467 41.0%
77 Iridium 191 191 Ir 191 Ir size 12{rSup { size 8{ 191 {}} }Ir} {} 190.960 584 37.3%
193 193 Ir 193 Ir size 12{rSup { size 8{ 193 {}} }Ir} {} 192.962 917 62.7%
78 Platinum 195 195 Pt 195 Pt size 12{rSup { size 8{ 195 {}} }Pt} {} 194.964 766 33.8%
79 Gold 197 197 Au 197 Au size 12{rSup { size 8{ 197 {}} }Au} {} 196.966 543 100%
198 198 Au 198 Au size 12{rSup { size 8{ 198 {}} }Au} {} 197.968 217 β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 2.696 d
80 Mercury 199 199 Hg 199 Hg size 12{rSup { size 8{ 199 {}} }Hg} {} 198.968 253 16.87%
202 202 Hg 202 Hg size 12{rSup { size 8{ 202 {}} }Hg} {} 201.970 617 29.86%
81 Thallium 205 205 Tl 205 Tl size 12{rSup { size 8{ 205{}} }Tl} {} 204.974 401 70.48%
82 Lead 206 206 Pb 206 Pb size 12{rSup { size 8{ 206{}} }Pb} {} 205.974 440 24.1%
207 207 Pb 207 Pb size 12{rSup { size 8{ 207{}} }Pb} {} 206.975 872 22.1%
208 208 Pb 208 Pb size 12{rSup { size 8{ 208{}} }Pb} {} 207.976 627 52.4%
210 210 Pb 210 Pb size 12{rSup { size 8{ 210{}} }Pb} {} 209.984 163 α,β−α,β− size 12{α,β rSup { size 8{ - {}} } } {} ­ 22.3 y
211 211 Pb 211 Pb size 12{rSup { size 8{ 211{}} }Pb} {} 210.988 735 β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 36.1 min
212 212 Pb 212 Pb size 12{rSup { size 8{ 212{}} }Pb} {} 211.991 871 β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 10.64 h
83 Bismuth 209 209 Bi 209 Bi size 12{rSup { size 8{ 209{}} }Bi} {} 208.980 374 100%
211 211 Bi 211 Bi size 12{rSup { size 8{ 211{}} }Bi} {} 210.987 255 α , β − α , β − size 12{α,β rSup { size 8{ - {}} } } {} 2.14 min
84 Polonium 210 210 Po 210 Po size 12{rSup { size 8{ 210{}} }Po} {} 209.982 848 α α size 12{α} {} 138.38 d
85 Astatine 218 218 At 218 At size 12{rSup { size 8{ 218{}} }At} {} 218.008 684 α , β − α , β − size 12{α,β rSup { size 8{ - {}} } } {} 1.6 s
86 Radon 222 222 Rn 222 Rn size 12{rSup { size 8{ 222{}} }Rn} {} 222.017 570 α α size 12{α} {} 3.82 d
87 Francium 223 223 Fr 223 Fr size 12{rSup { size 8{ 223{}} }Fr} {} 223.019 733 α , β − α , β − size 12{α,β rSup { size 8{ - {}} } } {} 21.8 min
88 Radium 226 226 Ra 226 Ra size 12{rSup { size 8{ 226{}} }Ra} {} 226.025 402 α α size 12{α} {} 1 . 60 × 10 3 y 1 . 60 × 10 3 y size 12{1 "." "60" times "10" rSup { size 8{3} } y} {}
89 Actinium 227 227 Ac 227 Ac size 12{rSup { size 8{ 227{}} }Ac} {} 227.027 750 α , β − α , β − size 12{α,β rSup { size 8{ - {}} } } {} 21.8 y
90 Thorium 228 228 Th 228 Th size 12{rSup { size 8{ 228{}} }Th} {} 228.028 715 α α size 12{α} {} 1.91 y
232 232 Th 232 Th size 12{rSup { size 8{ 232{}} }Th} {} 232.038 054 100%, αα size 12{α} {} 1 . 41 × 10 10 y 1 . 41 × 10 10 y size 12{1 "." "41" times "10" rSup { size 8{"10"} } y} {}
91 Protactinium 231 231 Pa 231 Pa size 12{rSup { size 8{ 231{}} }Pa} {} 231.035 880 α α size 12{α} {} 3 . 28 × 10 4 y 3 . 28 × 10 4 y size 12{3 "." "28" times "10" rSup { size 8{4} } y} {}
92 Uranium 233 233 U 233 U size 12{rSup { size 8{ 233{}} }U} {} 233.039 628 α α size 12{α} {} 1 . 59 × 10 3 y 1 . 59 × 10 3 y size 12{1 "." "59" times "10" rSup { size 8{3} } y} {}
235 235 U 235 U size 12{rSup { size 8{ 235{}} }U} {} 235.043 924 0.720%, αα size 12{α} {} 7 . 04 × 10 8 y 7 . 04 × 10 8 y size 12{7 "." "04" times "10" rSup { size 8{8} } y} {}
236 236 U 236 U size 12{rSup { size 8{ 236{}} }U} {} 236.045 562 α α size 12{α} {} 2 . 34 × 10 7 y 2 . 34 × 10 7 y size 12{2 "." "34" times "10" rSup { size 8{7} } y} {}
238 238 U 238 U size 12{rSup { size 8{ 238{}} }U} {} 238.050 784 99.2745%, αα size 12{α} {} 4 . 47 × 10 9 y 4 . 47 × 10 9 y size 12{4 "." "47" times "10" rSup { size 8{9} } y} {}
239 239 U 239 U size 12{rSup { size 8{ 239{}} }U} {} 239.054 289 β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 23.5 min
93 Neptunium 239 239 Np 239 Np size 12{rSup { size 8{ 239{}} }Np} {} 239.052 933 β−β− size 12{β rSup { size 8{ - {}} } } {} ­ 2.355 d
94 Plutonium 239 239 Pu 239 Pu size 12{rSup { size 8{ 239{}} }Pu} {} 239.052 157 α α size 12{α} {} 2 . 41 × 10 4 y 2 . 41 × 10 4 y size 12{2 "." "41" times "10" rSup { size 8{4} } y} {}
95 Americium 243 243 Am 243 Am size 12{rSup { size 8{ 243{}} }Am} {} 243.061 375 α,α, size 12{α,} {} fission 7 . 37 × 10 3 y 7 . 37 × 10 3 y size 12{7 "." "37" times "10" rSup { size 8{3} } y} {}
96 Curium 245 245 Cm 245 Cm size 12{rSup { size 8{ 245{}} }Cm} {} 245.065 483 α α size 12{α} {} 8 . 50 × 10 3 y 8 . 50 × 10 3 y size 12{8 "." "50" times "10" rSup { size 8{3} } y} {}
97 Berkelium 247 247 Bk 247 Bk size 12{rSup { size 8{ 247{}} }Bk} {} 247.070 300 α α size 12{α} {} 1 . 38 × 10 3 y 1 . 38 × 10 3 y size 12{1 "." "38" times "10" rSup { size 8{3} } y} {}
98 Californium 249 249 Cf 249 Cf size 12{rSup { size 8{ 249{}} }Cf} {} 249.074 844 α α size 12{α} {} 351 y
99 Einsteinium 254 254 Es 254 Es size 12{rSup { size 8{ 254{}} }Es} {} 254.088 019 α,β−α,β− size 12{α,β rSup { size 8{ - {}} } } {} ­ 276 d
100 Fermium 253 253 Fm 253 Fm size 12{rSup { size 8{ 253{}} }Fm} {} 253.085 173 EC, αα size 12{α} {} 3.00 d
101 Mendelevium 255 255 Md 255 Md size 12{rSup { size 8{ 255{}} }Md} {} 255.091 081 EC, αα size 12{α} {} 27 min
102 Nobelium 255 255 No 255 No size 12{rSup { size 8{ 255{}} }No} {} 255.093 260 EC, αα size 12{α} {} 3.1 min
103 Lawrencium 257 257 Lr 257 Lr size 12{rSup { size 8{ 257{}} }Lr} {} 257.099 480 EC, αα size 12{α} {} 0.646 s
104 Rutherfordium 261 261 Rf 261 Rf size 12{rSup { size 8{ 261{}} }Rf} {} 261.108 690 α α size 12{α} {} 1.08 min
105 Dubnium 262 262 Db 262 Db size 12{rSup { size 8{ 262{}} }Db} {} 262.113 760 α,α, size 12{α,} {} fission 34 s
106 Seaborgium 263 263 Sg 263 Sg size 12{rSup { size 8{ 263{}} }Sg} {} 263.11 86 α,α, size 12{α,} {} fission 0.8 s
107 Bohrium 262 262 Bh 262 Bh size 12{rSup { size 8{ 262{}} }Bh} {} 262.123 1 α α size 12{α} {} 0.102 s
108 Hassium 264 264 Hs 264 Hs size 12{rSup { size 8{ 264{}} }Hs} {} 264.128 5 α α size 12{α} {} 0.08 ms
109 Meitnerium 266 266 Mt 266 Mt size 12{rSup { size 8{ 266{}} }Mt} {} 266.137 8 α α size 12{α} {} 3.4 ms
Table A1

Atomic Masses