Isotopes of astatine

Astatine (85At) has 41 known isotopes, all of which are radioactive, whose mass numbers range from 188 to 229 except 189; they are accompanied by almost as many metastable excited states. The longest-lived isotope is 210At, which has a half-life of 8.1 hours, followed by the medically useful 211At, with a half-life of 7.214 hours. The longest-lived isomer is 202m1At with a half-life of just over 3 minutes. However, the longest-lived isotope existing in naturally occurring decay chains is 219At with a half-life of only 56 seconds.

List of isotopes

|-id=Astatine-188 | rowspan=2|188At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 103 | rowspan=2| | rowspan=2 style="text-align:center" | 2025 | rowspan=2| | α (~50%) | 184Bi | rowspan=2| | rowspan=2| |- | p (~50%) | 187Po |-id=Astatine-190 | 190At | style="text-align:right" | 85 | style="text-align:right" | 105 | | style="text-align:center" | 2023 | | α | 186Bi | (10−) | |-id=Astatine-191 | 191At | style="text-align:right" | 85 | style="text-align:right" | 106 | 191.004148(17) | style="text-align:center" | 2003 | 2.1(8) ms | α | 187Bi | 1/2+ | |-id=Astatine-191m | style="text-indent:1em" | 191mAt | colspan="3" style="text-indent:2em" | 58(20) keV | style="text-align:center" | 2003 | 2.2(4) ms | α | 187Bi | (7/2−) | |-id=Astatine-192 | 192At | style="text-align:right" | 85 | style="text-align:right" | 107 | 192.003141(3) | style="text-align:center" | 2006 | 11.5(6) ms | α | 188Bi | 3+# | |-id=Astatine-192m | style="text-indent:1em" | 192mAt | colspan="3" style="text-indent:2em" | 0(40) keV | style="text-align:center" | 2006 | 88(6) ms | α | 188m2Bi | (9−, 10−) | |-id=Astatine-193 | 193At | style="text-align:right" | 85 | style="text-align:right" | 108 | 192.999928(23) | style="text-align:center" | 2003 | 29(5) ms | α | 189Bi | 1/2+ | |-id=Astatine-193m1 | style="text-indent:1em" | 193m1At | colspan="3" style="text-indent:2em" | 8(9) keV | style="text-align:center" | 2003 | 21(5) ms | α | 189m1Bi | 7/2− | |-id=Astatine-193m2 | rowspan=2 style="text-indent:1em" | 193m2At | rowspan=2 colspan="3" style="text-indent:2em" | 42(9) keV | rowspan=2 style="text-align:center" | 2003 | rowspan=2|28(4) ms | IT (76%) | 193At | rowspan=2|13/2+ | rowspan=2| |- | α (24%) | 189m2Bi |-id=Astatine-194 | rowspan=3|194At | rowspan=3 style="text-align:right" | 85 | rowspan=3 style="text-align:right" | 109 | rowspan=3|193.999231(25) | rowspan=3 style="text-align:center" | 2009 | rowspan=3|286(7) ms | α (91.7%#) | 190Bi | rowspan=3|(5−) | rowspan=3| |- | β+ (8.3%#) | 194Po |- | β+, SF (0.032%#) | (various) |-id=Astatine-194m | rowspan=3 style="text-indent:1em" | 194mAt | rowspan=3 colspan="3" style="text-indent:2em" | −20(40) keV | rowspan=3 style="text-align:center" | 2009 | rowspan=3|323(7) ms | α (91.7%#) | 190Bi | rowspan=3|10− | rowspan=3| |- | β+ (8.3%#) | 194Po |- | β+, SF (0.032%#) | (various) |-id=Astatine-195 | rowspan=2|195At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 110 | rowspan=2|194.996274(10) | rowspan=2 style="text-align:center" | 1999 | rowspan=2|290(20) ms | α | 191m1Bi | rowspan=2|1/2+ | rowspan=2| |- | β+ ? | 195Po |-id=Astatine-195m | rowspan=3 style="text-indent:1em" | 195mAt | rowspan=3 colspan="3" style="text-indent:2em" | 29(7) keV | rowspan=3 style="text-align:center" | 1999 | rowspan=3|143(3) ms | α (88%) | 191Bi | rowspan=3|7/2- | rowspan=3| |- | IT (12%) | 195At |- | β+? | 195Po |-id=Astatine-196 | rowspan=3|196At | rowspan=3 style="text-align:right" | 85 | rowspan=3 style="text-align:right" | 111 | rowspan=3|195.99580(3) | rowspan=3 style="text-align:center" | 1967 | rowspan=3|377(4) ms | α (97.5%) | 192Bi | rowspan=3|(3+) | rowspan=3| |- | β+ (2.5%) | 196Po |- | β+, SF (0.009%) | (various) |-id=Astatine-196m1 | style="text-indent:1em" | 196m1At | colspan="3" style="text-indent:2em" | −40(40) keV | style="text-align:center" | (1996)Half-life not measured, not included in discovery database | 20# ms | α | 192mBi | 10−# | |-id=Astatine-196m2 | style="text-indent:1em" | 196m2At | colspan="3" style="text-indent:2em" | 157.9(1) keV | style="text-align:center" | 2000 | 11(2) μs | IT | 196At | (5+) | |-id=Astatine-197 | rowspan=2|197At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 112 | rowspan=2|196.993177(9) | rowspan=2 style="text-align:center" | 1967 | rowspan=2|388.2(56) ms | α (96.1%) | 193Bi | rowspan=2|9/2− | rowspan=2| |- | β+ (3.9%) | 197Po |-id=Astatine-197m1 | rowspan=3 style="text-indent:1em" | 197m1At | rowspan=3 colspan="3" style="text-indent:2em" | 45(8) keV | rowspan=3 style="text-align:center" | 1986 | rowspan=3|2.0(2) s | α | 193m1Bi | rowspan=3|1/2+ | rowspan=3| |- | IT (<0.004%) | 197At |- | β+? | 197Po |-id=Astatine-197m2 | style="text-indent:1em" | 197m2At | colspan="3" style="text-indent:2em" | 310.7(2) keV | style="text-align:center" | 1999 | 1.3(2) μs | IT | 197At | 13/2+ | |-id=Astatine-198 | rowspan=2|198At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 113 | rowspan=2|197.992798(5) | rowspan=2 style="text-align:center" | 1967 | rowspan=2|4.47(5) s | α (97%) | 194Bi | rowspan=2|3+ | rowspan=2| |- | β+ (3%) | 198Po |-id=Astatine-198m | rowspan=3 style="text-indent:1em" | 198mAt | rowspan=3 colspan="3" style="text-indent:2em" | 266.6(27) keV | rowspan=3 style="text-align:center" | 1967 | rowspan=3|1.23(5) s | α (93%) | 194Bi | rowspan=3|10− | rowspan=3| |- | β+ ? | 198Po |- | IT ? | 198At |-id=Astatine-199 | rowspan=2|199At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 114 | rowspan=2|198.990528(6) | rowspan=2 style="text-align:center" | 1967 | rowspan=2|7.02(12) s | α (89%) | 195Bi | rowspan=2|9/2− | rowspan=2| |- | β+ (11%) | 199Po |-id=Astatine-199m1 | rowspan=2 style="text-indent:1em" | 199m1At | rowspan=2 colspan="3" style="text-indent:2em" | 244.0(10) keV | rowspan=2 style="text-align:center" | 2013 | rowspan=2|273(9) ms | IT (99%) | 199At | rowspan=2|1/2+ | rowspan=2| |- | α (1%) | 195Bi |-id=Astatine-199m2 | style="text-indent:1em" | 199m2At | colspan="3" style="text-indent:2em" | 572.9(1) keV | style="text-align:center" | (2000) Half-life shorter than 100ns, not included in discovery database | 70(20) ns | IT | 199At | 13/2+ | |-id=Astatine-199m3 | style="text-indent:1em" | 199m3At | colspan="3" style="text-indent:2em" | 2293.4(5) keV | style="text-align:center" | 2010 | 800(50) ns | IT | 199m2At | (29/2+) | |-id=Astatine-200 | rowspan=2|200At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 115 | rowspan=2|199.990351(26) | rowspan=2 style="text-align:center" | 1963 | rowspan=2|43.2(9) s | α (52%) | 196Bi | rowspan=2|(3+) | rowspan=2| |- | β+ (48%) | 200Po |-id=Astatine-200m1 | rowspan=3 style="text-indent:1em" | 200m1At | rowspan=3 colspan="3" style="text-indent:2em" | 112.9(29) keV | rowspan=3 style="text-align:center" | 1992 | rowspan=3|47(1) s | β+ (57%) | 200Po | rowspan=3|(7+) | rowspan=3| |- | α (43%) | 196Bi |- | IT ? | 200At |-id=Astatine-200m2 | rowspan=3 style="text-indent:1em" | 200m2At | rowspan=3 colspan="3" style="text-indent:2em" | 343.8(30) keV | rowspan=3 style="text-align:center" | 1967 | rowspan=3|8.0(21) s | IT ? | 200At | rowspan=3|(10−) | rowspan=3| |- | α (10.5%) | 196Bi |- | β+ ? | 200Po |-id=Astatine-201 | rowspan=2|201At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 116 | rowspan=2|200.988417(9) | rowspan=2 style="text-align:center" | 1963 | rowspan=2|85.2(16) s | α (71%) | 197Bi | rowspan=2|9/2− | rowspan=2| |- | β+ (29%) | 201Po |-id=Astatine-201m1 | style="text-indent:1em" | 201m1At | colspan="3" style="text-indent:2em" | 459(1) keV | style="text-align:center" | 2014 | 45(3) ms | IT | 201At | 1/2+ | |-id=Astatine-201m2 | style="text-indent:1em" | 201m2At | colspan="3" style="text-indent:2em" | 2319.8(3) keV | style="text-align:center" | 2015 | 3.39(9) μs | IT | 201At | 29/2+ | |-id=Astatine-202 | rowspan=2|202At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 117 | rowspan=2|201.988626(30) | rowspan=2 style="text-align:center" | 1961 | rowspan=2|184(1) s | β+ (88%) | 202Po | rowspan=2|3+ | rowspan=2| |- | α (12%) | 198Bi |-id=Astatine-202m1 | rowspan=3 style="text-indent:1em" | 202m1At | rowspan=3 colspan="3" style="text-indent:2em" | 190(40) keV | rowspan=3 style="text-align:center" | 1992 | rowspan=3|182(2) s | β+ (91.5%) | 202Po | rowspan=3|7+ | rowspan=3| |- | α (8.5%) | 198Bi |- | IT ? | 202At |-id=Astatine-202m2 | rowspan=3 style="text-indent:1em" | 202m2At | rowspan=3 colspan="3" style="text-indent:2em" | 590(40) keV | rowspan=3 style="text-align:center" | 1992 | rowspan=3|460(50) ms | IT (99.904%) | 202At | rowspan=3|10− | rowspan=3| |- | α (0.096%) | 198Bi |- | IT ? | 202At |-id=Astatine-203 | rowspan=2|203At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 118 | rowspan=2|202.986943(11) | rowspan=2 style="text-align:center" | 1951 | rowspan=2|7.4(2) min | β+ (69%) | 203Po | rowspan=2|9/2− | rowspan=2| |- | α (31%) | 199Bi |-id=Astatine-203m1 | style="text-indent:1em" | 203m1At | colspan="3" style="text-indent:2em" | 683.4(3) keV | style="text-align:center" | 2017 | 3.5(6) ms | IT | 203At | 1/2+ | |-id=Astatine-203m2 | style="text-indent:1em" | 203m2At | colspan="3" style="text-indent:2em" | 2330.1(4) keV | style="text-align:center" | 2018 | 9.77(21) μs | IT | 203At | 29/2+ | |-id=Astatine-204 | rowspan=2|204At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 119 | rowspan=2|203.987251(24) | rowspan=2 style="text-align:center" | 1961 | rowspan=2|9.12(11) min | β+ (96.2%) | 204Po | rowspan=2|7+ | rowspan=2| |- | α (3.8%) | 200Bi |-id=Astatine-204m | style="text-indent:1em" | 204mAt | colspan="3" style="text-indent:2em" | 587.30(20) keV | style="text-align:center" | 1975 | 108(10) ms | IT | 204At | 10− | |-id=Astatine-205 | rowspan=2|205At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 120 | rowspan=2|204.986061(13) | rowspan=2 style="text-align:center" | 1951 | rowspan=2|26.9(8) min | β+ (90%) | 205Po | rowspan=2|9/2− | rowspan=2| |- | α (10%) | 201Bi |-id=Astatine-205m | style="text-indent:1em" | 205mAt | colspan="3" style="text-indent:2em" | 2339.64(23) keV | style="text-align:center" | 1982 | 7.76(14) μs | IT | 205At | 29/2+ | |-id=Astatine-206 | rowspan=2|206At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 121 | rowspan=2|205.986646(15) | rowspan=2 style="text-align:center" | 1961 | rowspan=2|30.6(8) min | β+ (99.1%) | 206Po | rowspan=2|(6)+ | rowspan=2| |- | α (0.9%) | 202Bi |-id=Astatine-206m | style="text-indent:1em" | 206mAt | colspan="3" style="text-indent:2em" | 810(2) keV | style="text-align:center" | 1999 | 813(21) ns | IT | 206At | (10)− | |-id=Astatine-207 | rowspan=2|207At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 122 | rowspan=2|206.985800(13) | rowspan=2 style="text-align:center" | 1951 | rowspan=2|1.81(3) h | β+ (~90%) | 207Po | rowspan=2|9/2− | rowspan=2| |- | α (~10%) | 203Bi |-id=Astatine-207m1 | style="text-indent:1em" | 207m1At | colspan="3" style="text-indent:2em" | 2117.3(6) keV | style="text-align:center" | 1978 | 108(2) ns | IT | 207At | 25/2+ | |-id=Astatine-207m2 | style="text-indent:1em" | 207m2At | colspan="3" style="text-indent:2em" | 2384.6(2) keV | style="text-align:center" | 2023 | ~3.5 μs | IT | 207At | 29/2+ | |-id=Astatine-208 | rowspan=2|208At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 123 | rowspan=2|207.986613(10) | rowspan=2 style="text-align:center" | 1950 | rowspan=2|1.63(3) h | β+ (99.45%) | 208Po | rowspan=2|6+ | rowspan=2| |- | α (0.55%) | 204Bi |-id=Astatine-208m | style="text-indent:1em" | 208mAt | colspan="3" style="text-indent:2em" | 2276.4(18) keV | style="text-align:center" | 1984 | 1.5(2) μs | IT | 208At | 16- |