Bismuth (83Bi) has 41 known isotopes, ranging from 184Bi to 224Bi. Bismuth has one nearly stable isotope but no stable isotopes, the standard atomic weight can be given from that isotope, bismuth-209. Though it is now known to be radioactive, it may still be considered practically stable because it has a half-life of 2.01×1019 years, which is more than a billion times the age of the universe. As a result, it is the longest lived known alpha emitter. Bismuth-209 is also the heaviest nearly stable isotope, with the longest lived isotope with a greater atomic weight being thorium-232.
Besides 209Bi, the most stable bismuth radioisotopes are 210mBi with a half-life of 3.04 million years, 208Bi with a half-life of 368,000 years and 207Bi, with a half-life of 31.22 years, none of which occur in nature. All other isotopes have half-lives under 15 days, most under two hours. Of naturally occurring radioisotopes, the most stable is radiogenic 210Bi with a half-life of 5.012 days. 210mBi is unusual for being a nuclear isomer with a half-life many orders of magnitude longer than that of the ground state.
List of isotopes
|-id=Bismuth-184 | 184Bi | | style="text-align:right" | 83 | style="text-align:right" | 101 | 184.001347(131)# | style="text-align:center" | 2003 | | α | 180Tl | 3+# | |-id=Bismuth-184m | style="text-indent:1em" | 184mBiOrder of ground state and isomer is uncertain. | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2003 | | α | 180Tl | 10−# | |-id=Bismuth-185 | rowspan=2|185Bi | rowspan=2| | rowspan=2 style="text-align:right" | 83 | rowspan=2 style="text-align:right" | 102 | rowspan=2|184.99760(9)# | rowspan=2 style="text-align:center" | 1996 | rowspan=2| | p (92%) | 184Pb | rowspan=2|(1/2+) | rowspan=2| |- | α (8%) | 181Tl |-id=Bismuth-185m | style="text-indent:1em" | 185mBi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2021 | | IT | 185Bi | (7/2−, 9/2−) | |-id=Bismuth-186 | rowspan=3|186Bi | rowspan=3| | rowspan=3 style="text-align:right" | 83 | rowspan=3 style="text-align:right" | 103 | rowspan=3|185.996623(18) | rowspan=3 style="text-align:center" | 1997 | rowspan=3| | α (99.99%) | 182Tl | rowspan=3|(3+) | rowspan=3| |- | β+ (?%) | 186Pb |- | β+, SF (0.011%) | (various) |-id=Bismuth-186m | rowspan=3 style="text-indent:1em" | 186mBi | rowspan=3| | rowspan=3 colspan="3" style="text-indent:2em" | | rowspan=3 style="text-align:center" | 1997 | rowspan=3| | α (99.99%) | 182Tl | rowspan=3|(10−) | rowspan=3| |- | β+ (?%) | 186Pb |- | β+, SF (0.011%) | (various) |-id=Bismuth-187 | 187Bi | | style="text-align:right" | 83 | style="text-align:right" | 104 | 186.993147(11) | style="text-align:center" | 1999 | | α | 183Tl | (9/2−) | |-id=Bismuth-187m1 | style="text-indent:1em" | 187m1Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 1999 | | α | 183Tl | 1/2+ | |-id=Bismuth-187m2 | style="text-indent:1em" | 187m2Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2002 | | IT | 187Bi | (13/2+) | |-id=Bismuth-188 | rowspan=2|188Bi | rowspan=2| | rowspan=2 style="text-align:right" | 83 | rowspan=2 style="text-align:right" | 105 | rowspan=2|187.992276(12) | rowspan=2 style="text-align:center" | 1980 | rowspan=2| | α | 184Tl | rowspan=2|(3+) | rowspan=2| |- | β+, SF (0.0014%) | (various) |-id=Bismuth-188m1 | style="text-indent:1em" | 188m1Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2006
| 7+# | |-id=Bismuth-188m2 | rowspan=2 style="text-indent:1em" | 188m2Bi | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | | rowspan=2 style="text-align:center" | 1997 | rowspan=2| | α | 184Tl | rowspan=2|(10−) | rowspan=2| |- | β+, SF (0.0046%) | (various) |-id=Bismuth-188m3 | style="text-indent:1em" | 188m3Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2022 | | IT |188Bi
|-id=Bismuth-189 | 189Bi | | style="text-align:right" | 83 | style="text-align:right" | 106 | 188.989195(22) | style="text-align:center" | 1973 | | α | 185Tl | 9/2− | |-id=Bismuth-189m1 | rowspan=2 style="text-indent:1em" | 189m1Bi | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | | rowspan=2 style="text-align:center" | 1993 | rowspan=2| | α (83%) | 185Tl | rowspan=2|1/2+ | rowspan=2| |- | IT (17%) | 189Bi |-id=Bismuth-189m2 | style="text-indent:1em" | 189m2Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2001 | | IT | 189Bi | 13/2+ | |-id=Bismuth-190 | rowspan=3|190Bi | rowspan=3| | rowspan=3 style="text-align:right" | 83 | rowspan=3 style="text-align:right" | 107 | rowspan=3|189.988625(23) | rowspan=3 style="text-align:center" | 1972 | rowspan=3| | α (77%) | 186Tl | rowspan=3|(3+) | rowspan=3| |- | β+ (23%) | 190Pb |- | β+, SF (6×10−6%) | (various) |-id=Bismuth-190m1 | rowspan=3 style="text-indent:1em" | 190m1Bi | rowspan=3| | rowspan=3 colspan="3" style="text-indent:2em" | | rowspan=3 style="text-align:center" | 1988 | rowspan=3| | α (70%) | 186Tl | rowspan=3|10− | rowspan=3| |- | β+ (30%) | 190Pb |- | β+, SF (4×10−6%) | (various) |-id=Bismuth-190m2 | style="text-indent:1em" | 190m2Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2009 | | IT | 190Bi | (5−) | |-id=Bismuth-190m3 | style="text-indent:1em" | 190m3Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2001 | | IT | 190Bi | (8−) | |-id=Bismuth-191 | rowspan=2|191Bi | rowspan=2| | rowspan=2 style="text-align:right" | 83 | rowspan=2 style="text-align:right" | 108 | rowspan=2|190.985787(8) | rowspan=2 style="text-align:center" | 1972 | rowspan=2| | α (51%) | 187Tl | rowspan=2|9/2− | rowspan=2| |- | β+ (49%) | 191Pb |-id=Bismuth-191m1 | rowspan=3 style="text-indent:1em" | 191m1Bi | rowspan=3| | rowspan=3 colspan="3" style="text-indent:2em" | | rowspan=3 style="text-align:center" | 1981 | rowspan=3| | α (68%) | 187Tl | rowspan=3|1/2+ | rowspan=3| |- | IT (?%) | 191Bi |- | β+ (?%) | 191Pb |-id=Bismuth-191m2 | style="text-indent:1em" | 191m2Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2004 | | IT | 191Bi | 13/2+ | |-id=Bismuth-191m3 | style="text-indent:1em" | 191m3Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2004 | | IT | 191Bi | 25/2-# | |-id=Bismuth-192 | rowspan=2|192Bi | rowspan=2| | rowspan=2 style="text-align:right" | 83 | rowspan=2 style="text-align:right" | 109 | rowspan=2|191.98547(3) | rowspan=2 style="text-align:center" | 1970 | rowspan=2| | β+ (88%) | 192Pb | rowspan=2|(3+) | rowspan=2| |- | α (12%) | 188Tl |-id=Bismuth-192m | rowspan=2 style="text-indent:1em" | 192mBi | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | | rowspan=2 style="text-align:center" | 1987 | rowspan=2| | β+ (90%) | 192Pb | rowspan=2|10− | rowspan=2| |- | α (10%) | 188Tl |-id=Bismuth-193 | rowspan=2|193Bi | rowspan=2| | rowspan=2 style="text-align:right" | 83 | rowspan=2 style="text-align:right" | 110 | rowspan=2|192.982947(8) | rowspan=2 style="text-align:center" | 1970 | rowspan=2| | β+ (96.5%) | 193Pb | rowspan=2|9/2− | rowspan=2| |- | α (3.5%) | 189Tl |-id=Bismuth-193m1 | rowspan=2 style="text-indent:1em" | 193m1Bi | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | | rowspan=2 style="text-align:center" | 1971 | rowspan=2| | α (84%) | 189Tl | rowspan=2|1/2+ | rowspan=2| |- | β+ (16%) | 193Pb |-id=Bismuth-193m2 | style="text-indent:1em" | 193m2Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2004 | | IT | 193Bi | 13/2+ | |-id=Bismuth-193m3 | style="text-indent:1em" | 193m3Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2004 | | IT | 193Bi | 29/2+ | |-id=Bismuth-193m4 | style="text-indent:1em" | 193m4Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2004 | | IT | 193Bi | (29/2−) | |-id=Bismuth-194 | rowspan=2|194Bi | rowspan=2| | rowspan=2 style="text-align:right" | 83 | rowspan=2 style="text-align:right" | 111 | rowspan=2|193.982799(6) | rowspan=2 style="text-align:center" | 1970 | rowspan=2| | β+ (99.54%) | 194Pb | rowspan=2|3+ | rowspan=2| |- | α (0.46%) | 190Tl |-id=Bismuth-194m1 | style="text-indent:1em" | 194m1Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 1976 | | β+ | 194Pb | (6+, 7+) | |-id=Bismuth-194m2 | rowspan=2 style="text-indent:1em" | 194m2Bi | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | | rowspan=2 style="text-align:center" | 1988 | rowspan=2| | β+ (99.80%) | 194Pb | rowspan=2|(10−) | rowspan=2| |- | α (0.20%) | 190Tl |-id=Bismuth-195 | rowspan=2|195Bi | rowspan=2| | rowspan=2 style="text-align:right" | 83 | rowspan=2 style="text-align:right" | 112 | rowspan=2|194.980649(6) | rowspan=2 style="text-align:center" | 1970 | rowspan=2| | β+ (99.97%) | 195Pb | rowspan=2|9/2− | rowspan=2| |- | α (0.030%) | 191Tl |-id=Bismuth-195m1 | rowspan=2 style="text-indent:1em" | 195m1Bi | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | | rowspan=2 style="text-align:center" | 1974 | rowspan=2| | β+ (67%) | 195Pb | rowspan=2|1/2+ | rowspan=2| |- | α (33%) | 191Tl |-id=Bismuth-195m2 | style="text-indent:1em" | 195m2Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 1986 | | IT | 195Bi | (29/2−) | |-id=Bismuth-195m3 | style="text-indent:1em" | 195m3Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 2015 | | IT | 195Bi | 29/2+ | |-id=Bismuth-196 | rowspan=2|196Bi | rowspan=2| | rowspan=2 style="text-align:right" | 83 | rowspan=2 style="text-align:right" | 113 | rowspan=2|195.980667(26) | rowspan=2 style="text-align:center" | 1976 | rowspan=2| | β+ | 196Pb | rowspan=2|(3+) | rowspan=2| |- | α (0.00115%) | 192Tl |-id=Bismuth-196m1 | style="text-indent:1em" | 196m1Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 1987 | | IT | 196Bi | (7+) | |-id=Bismuth-196m2 | rowspan=3 style="text-indent:1em" | 196m2Bi | rowspan=3| | rowspan=3 colspan="3" style="text-indent:2em" | | rowspan=3 style="text-align:center" | 1987 | rowspan=3| | β+ (74.2%) | 196Pb | rowspan=3| (10−) | rowspan=3| |- | IT (25.8%) | 196Bi |- | α (3.8×10−4%) | 192Tl |-id=Bismuth-197 | 197Bi | | style="text-align:right" | 83 | style="text-align:right" | 114 | 196.978865(9) | style="text-align:center" | 1970 | | β+ | 197Pb | 9/2− | |-id=Bismuth-197m1 | rowspan=2 style="text-indent:1em" | 197m1Bi | rowspan=2| | rowspan=2 colspan="3" style="text-indent:2em" | | rowspan=2 style="text-align:center" | 1991 | rowspan=2| | α (55%) | 193Tl | rowspan=2|1/2+ | rowspan=2| |- | β+ (45%) | 197Pb |-id=Bismuth-197m2 | style="text-indent:1em" | 197m2Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 1986 | | IT | 197Bi | (29/2−) | |-id=Bismuth-197m3 | style="text-indent:1em" | 197m3Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 1986 | | IT | 197Bi | (31/2−) | |-id=Bismuth-198 | 198Bi | | style="text-align:right" | 83 | style="text-align:right" | 115 | 197.979201(30) | style="text-align:center" | 1950 | | β+ | 198Pb | 3+ | |-id=Bismuth-198m1 | style="text-indent:1em" | 198m1Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 1992 | | β+ | 198Pb | 7+ | |-id=Bismuth-198m2 | style="text-indent:1em" | 198m2Bi | | colspan="3" style="text-indent:2em" | | style="text-align:center" | 1972 | | IT | 198Bi | 10− | |-id=Bismuth-199 | 199Bi | | style="text-align:right" | 83 | style="text-align:right" | 116 | 198.977673(11) | style="text-align:center" | 1950 | | β+ | 199Pb | 9/2− | |-id=Bismuth-199m1 | rowspan=3 style="text-indent:1em" | 199m1Bi | rowspan=3| | rowspan=3 colspan="3" style="text-indent:2em" | | rowspan=3 style="text-align:center" | 1964 | rowspan=3| | β+ (>98%) | 199Pb | rowspan=3|(1/2+) | rowspan=3| |- | IT (<2%) | 199Bi |- | α (0.01%) | 195Tl |-id=Bismuth-199m2 | style="text-indent:1em" | 199m2Bi | | colspan="3" style="text-indent:2em" |