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Relative Atomic Masses and Half-Lives of Selected Radionuclides (© 1998 IUPAC).
[Abbreviations for units are: a = year; d = day; h = hour; min = minute; s = second; ms = millisecond. Names of elements with atomic numbers 110, 111 and 112 are temporary.]
Atomic
Number		 Name Symbol Mass
Number		 Relative
Atomic Mass		 Half-Life and
Uncertainty		 Unit
43 Technetium Tc 97 96.9064 2.6±0.4×106 a
98 97.9072 4.2±0.3×106 a
99 98.9063 2.1±0.3×105 a
61 Promethium Pm 145 144.9127 17.7±0.4 a
147 146.9151 2.623±0.003 a
84 Polonium Po 209 208.9824 102±5 a
210 209.9828 138.4±0.1 d
85 Astatine At 210 209.9871 8.1±0.4 h
211 210.9875 7.21±0.01 h
86 Radon Rn 211 210.9906 14.6±0.2 h
220 220.0114 55.6±0.1 s
222 222.0176 3.823±0.004 d
87 Francium Fr 223 223.0197 22.0±0.1 min
88 Radium Ra 223 223.0185 11.43±0.01 d
224 224.0202 3.66±0.02 d
226 226.0254 1599±4 a
228 228.0311 5.75±0.03 a
89 Actinium Ac 227 227.0277 21.77±0.02 a
90 Thorium Th 230 230.0331 7.54±0.03×104 a
232 232.0380 1.40±0.01 ×1010 a
91 Protactinium Pa 231 231.0359 3.25±0.01×104 a
92 Uranium U 233 233.0396 1.592±0.002×105 a
234 234.0409 2.455±0.006×105 a
235 235.0439 7.04±0.01×108 a
236 236.0456 2.342±0.004×107 a
238 238.0508 4.47±0.02×109 a
93 Neptunium Np 237 237.0482 2.14±0.01×106 a
239 239.0529 2.355±0.006 d
94 Plutonium Pu 238 238.0496 87.7±0.1 a
239 239.0522 2.410±0.003×104 a
240 240.0538 6.56±0.01×103 a
241 241.0568 14.4±0.1 a
242 242.0587 3.75±0.02×105 a
244 244.0642 8.00±0.09×107 a
95 Americium Am 241 241.0568 432.7±0.6 a
243 243.0614 7.37±0.02×103 a
96 Curium Cm 243 243.0614 29.1±0.1 a
244 244.0627 18.1±0.1 a
245 245.0655 8.48±0.06×103 a
246 246.0672 4.76±0.04×103 a
247 247.0703 1.56±0.05×107 a
248 248.0723 3.48±0.06×105 a
97 Berkelium Bk 247 247.0703 1.4±0.3×103 a
249 249.0750 3.20±0.06×102 d
98 Californium Cf 249 249.0748 351±2 a
250 250.0764 13.1±0.1 a
251 251.0796 9.0±0.5×102 a
252 252.0816 2.64±0.01 a
99 Einsteinium Es 252 252.0830 472±2 d
100 Fermium Fm 257 257.0951 100.5±0.2 d
101 Mendelevium Md 256 256.0941 78±2 min
258 258.0984 51.5±0.3 d
102 Nobelium No 259 259.1011 58±5 min
103 Lawrencium Lr 262 262.110 3.6±0.3 min
104 Rutherfordium Rf 261 261.1088 1.3 a min
105 Dubnium Db 262 262.1141 34±5 s
106 Seaborgium Sg 266 266.1219 21 a s
107 Bohrium Bh 264 264.1247 0.44 a s
108 Hassium Hs 269 269.1341 9.35 a, b s
109 Meitnerium Mt 268 268.1388 70 a, b ms
110 Ununnilium Uun 271 271.1461 1.1 a, b ms
111 Unununium Uuu 272 272.1535 1.5 a, b ms
112 Ununbium Uub 277 0.24 a, b ms
a   The uncertainties of these elements are asymmetric.
b   The value given is determined from only a few decays.