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| | α (~50%) | ¹⁸⁴Bi | rowspan=2| | rowspan=2| |- | p (~50%) | ¹⁸⁷Po |-id=Astatine-190 | ¹⁹⁰At | style="text-align:right" | 85 | style="text-align:right" | 105 | | | α | ¹⁸⁶Bi | (10−) | |-id=Astatine-191 | ¹⁹¹At | style="text-align:right" | 85 | style="text-align:right" | 106 | 191.004148(17) | 2.1(8)&nbsp;ms | α | ¹⁸⁷Bi | 1/2+ | |-id=Astatine-191m | style="text-indent:1em" | ^191mAt | colspan="3" style="text-indent:2em" | 58(20) keV | 2.2(4)&nbsp;ms | α | ¹⁸⁷Bi | (7/2−) | |-id=Astatine-192 | ¹⁹²At | style="text-align:right" | 85 | style="text-align:right" | 107 | 192.003141(3) | 11.5(6)&nbsp;ms | α | ¹⁸⁸Bi | 3+# | |-id=Astatine-192m | style="text-indent:1em" | ^192mAt | colspan="3" style="text-indent:2em" | 0(40)&nbsp;keV | 88(6)&nbsp;ms | α | ^188mBi | (9−, 10−) | |-id=Astatine-193 | ¹⁹³At | style="text-align:right" | 85 | style="text-align:right" | 108 | 192.999928(23) | 29(5)&nbsp;ms | α | ¹⁸⁹Bi | 1/2+ | |-id=Astatine-193m1 | style="text-indent:1em" | ^193m1At | colspan="3" style="text-indent:2em" | 8(9)&nbsp;keV | 21(5)&nbsp;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)&nbsp;keV | rowspan=2|28(4)&nbsp;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|286(7)&nbsp;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)&nbsp;keV | rowspan=3|323(7)&nbsp;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|290(20)&nbsp;ms | α | ^191mBi | 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)&nbsp;keV | rowspan=3|143(3)&nbsp;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|377(4)&nbsp;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)&nbsp;keV | 20#&nbsp;ms | α | ^192mBi | 10−# | |-id=Astatine-196m2 | style="text-indent:1em" | ^196m2At | colspan="3" style="text-indent:2em" | 157.9(1)&nbsp;keV | 11(2)&nbsp;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|388.2(56)&nbsp;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)&nbsp;keV | rowspan=3|2.0(2)&nbsp;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)&nbsp;keV | 1.3(2)&nbsp;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|4.47(5)&nbsp;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)&nbsp;keV | rowspan=3|1.23(5)&nbsp;s | α (93%) | | rowspan=3|10− | rowspan=3| |- | β⁺ ? | ¹⁹⁸Po |- | IT ? | ¹⁹⁸Po |-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|7.02(12)&nbsp;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)&nbsp;keV | rowspan=2|273(9)&nbsp;ms | IT (99%) | | 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)&nbsp;keV | 70(20)&nbsp;ns | IT | | 13/2+ | |-id=Astatine-199m3 | style="text-indent:1em" | ^199m3At | colspan="3" style="text-indent:2em" | 2293.4(5)&nbsp;keV | 800(50)&nbsp;ns | IT | | (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|43.2(9)&nbsp;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)&nbsp;keV | rowspan=3|47(1)&nbsp;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)&nbsp;keV | rowspan=3|8.0(21)&nbsp;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|85.2(16)&nbsp;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)&nbsp;keV | 45(3)&nbsp;ms | IT | | 1/2+ | |-id=Astatine-201m2 | style="text-indent:1em" | ^201m2At | colspan="3" style="text-indent:2em" | 459(1)&nbsp;keV | 3.39(9)&nbsp;μs | IT | | 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|184(1)&nbsp;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)&nbsp;keV | rowspan=3|182(2)&nbsp;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)&nbsp;keV | rowspan=3|460(50)&nbsp;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|7.4(2)&nbsp;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)&nbsp;keV | 3.5(6)&nbsp;ms | IT | | 1/2+ | |-id=Astatine-203m2 | style="text-indent:1em" | ^203m2At | colspan="3" style="text-indent:2em" | 2330.1(4)&nbsp;keV | 9.77(21)&nbsp;μs | IT | | 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|9.12(11)&nbsp;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)&nbsp;keV | 108(10)&nbsp;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|26.9(8)&nbsp;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)&nbsp;keV | 7.76(14)&nbsp;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|30.6(8)&nbsp;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)&nbsp;keV | 813(21)&nbsp;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|1.81(3)&nbsp;h | β⁺ (~90%) | ²⁰⁷Po | rowspan=2|9/2− | rowspan=2| |- | α (~10%) | ²⁰³Bi |-id=Astatine-207m | style="text-indent:1em" | ^207mAt | colspan="3" style="text-indent:2em" | 2117.3(6)&nbsp;keV | 108(2)&nbsp;ns | IT | ²⁰⁷At | 25/2+ | |-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|1.63(3)&nbsp;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)&nbsp;keV | 1.5(2)&nbsp;μs | IT | ²⁰⁸At | 16- | |-id=Astatine-209 | rowspan=2|²⁰⁹At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 124 | rowspan=2|208.986169(5) | rowspan=2|5.42(5)&nbsp;h | β⁺ (96.1%) | ²⁰⁹Po | rowspan=2|9/2− | rowspan=2| |- | α (3.9%) | ²⁰⁵Bi |-id=Astatine-209m | style="text-indent:1em" | ^209mAt | colspan="3" style="text-indent:2em" | 2429.32(22)&nbsp;keV | 916(10)&nbsp;ns | IT | ²⁰⁹At | 29/2+ | |-id=Astatine-210 | rowspan=2|²¹⁰At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 125 | rowspan=2|209.987147(8) | rowspan=2|8.1(4)&nbsp;h | β⁺ (99.825%) | ²¹⁰Po | rowspan=2|(5)+ | rowspan=2| |- | α (0.175%) | ²⁰⁶Bi |-id=Astatine-210m1 | style="text-indent:1em" | ^210m1At | colspan="3" style="text-indent:2em" | 2549.6(2)&nbsp;keV | 482(6)&nbsp;ns | IT | ²¹⁰At | (15)− | |-id=Astatine-210m2 | style="text-indent:1em" | ^210m2At | colspan="3" style="text-indent:2em" | 4027.7(2)&nbsp;keV | 5.66(7)&nbsp;μs | IT | ²¹⁰At | (19)+ | |-id=Astatine-211 | rowspan=2|²¹¹At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 126 | rowspan=2|210.9874962(29) | rowspan=2|7.214(7)&nbsp;h | EC (58.2%) | ²¹¹Po | rowspan=2|9/2− | rowspan=2| |- | α (41.8%) | ²⁰⁷Bi |-id=Astatine-211m | style="text-indent:1em" | ^211mAt | colspan="3" style="text-indent:2em" | 4814.5(5)&nbsp;keV | 4.23(7)&nbsp;μs | IT | ²¹¹At | (39/2-) | |-id=Astatine-212 | ²¹²At | style="text-align:right" | 85 | style="text-align:right" | 127 | 211.9907373(26) | 314(3)&nbsp;ms | α | ²⁰⁸Bi | (1−) | |-id=Astatine-212m1 | style="text-indent:1em" | ^212m1At | colspan="3" style="text-indent:2em" | 222.9(9)&nbsp;keV | 119(3)&nbsp;ms | α | ²⁰⁸Bi | (9−) | |-id=Astatine-212m2 | style="text-indent:1em" | ^212m2At | colspan="3" style="text-indent:2em" | 4771.4(15)&nbsp;keV | 152(5)&nbsp;μs | IT | ²¹²At | (25−) | |-id=Astatine-213 | ²¹³At | style="text-align:right" | 85 | style="text-align:right" | 128 | 212.992937(5) | 125(6)&nbsp;ns | α | ²⁰⁹Bi | 9/2− | |-id=Astatine-213m1 | style="text-indent:1em" | ^213m1At | colspan="3" style="text-indent:2em" | 1358(23)&nbsp;keV | 110(17)&nbsp;ns | IT | ²¹³At | 25/2-# | |-id=Astatine-213m2 | style="text-indent:1em" | ^213m2At | colspan="3" style="text-indent:2em" | 2998(27)&nbsp;keV | 45(4)&nbsp;μs | IT | ²¹³At | 49/2+# | |-id=Astatine-214 | ²¹⁴At | style="text-align:right" | 85 | style="text-align:right" | 129 | 213.996372(4) | 558(10)&nbsp;ns | α | ²¹⁰Bi | 1− | |-id=Astatine-214m1 | style="text-indent:1em" | ^214m1At | colspan="3" style="text-indent:2em" | 59(9)&nbsp;keV | 265(30)&nbsp;ns | α | ²¹⁰Bi | | |-id=Astatine-214m2 | style="text-indent:1em" | ^214m2At | colspan="3" style="text-indent:2em" | 232(5)&nbsp;keV | 760(15)&nbsp;ns | α | ^210mBi | 9− | |-id=Astatine-215 | ²¹⁵At | style="text-align:right" | 85 | style="text-align:right" | 130 | 214.998651(7) | 37(3)&nbsp;μs | α | ²¹¹Bi | 9/2− | Trace |-id=Astatine-216 | ²¹⁶At | style="text-align:right" | 85 | style="text-align:right" | 131 | 216.002423(4) | 300(30)&nbsp;μs | α | ²¹²Bi | 1− | |-id=Astatine-216m | style="text-indent:1em" | ^216mAt | colspan="3" style="text-indent:2em" | 161(11)&nbsp;keV | 100#&nbsp;μs | α | ^212m1Bi | 9−# | |-id=Astatine-217 | rowspan=2|²¹⁷At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 132 | rowspan=2|217.004718(5) | rowspan=2|32.6(3)&nbsp;ms | α (99.992%) | ²¹³Bi | rowspan=2|9/2− | rowspan=2|Trace |- | β^− (0.008%) | ²¹⁷Rn |-id=Astatine-218 | rowspan=2|²¹⁸At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 133 | rowspan=2|218.008696(12) | rowspan=2|1.28(6)&nbsp;s | α (~100%) | ²¹⁴Bi | rowspan=2|(2−,3−) | rowspan=2|Trace |- | β^− (?) | ²¹⁸Rn |-id=Astatine-219 | rowspan=2|²¹⁹At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 134 | rowspan=2|219.011161(3) | rowspan=2|56(3)&nbsp;s | α (93.6%) | ²¹⁵Bi | rowspan=2|(9/2−) | rowspan=2|Trace |- | β^− (6.4%) | ²¹⁹Rn |-id=Astatine-220 | rowspan=2|²²⁰At | rowspan=2 style="text-align:right" | 85 | rowspan=2 style="text-align:right" | 135 | rowspan=2|220.015433(15) | rowspan=2|3.71(4)&nbsp;min | β^− (92%) | ²²⁰Rn | rowspan=2|3(−#) | rowspan=2| |- | α (8%) | ²¹⁶Bi |-id=Astatine-221 | ²²¹At | style="text-align:right" | 85 | style="text-align:right" | 136 | 221.018017(15) | 2.3(2)&nbsp;min | β^− | ²²¹Rn | 3/2−# | |-id=Astatine-222 | ²²²At | style="text-align:right" | 85 | style="text-align:right" | 137 | 222.022494(17) | 54(10)&nbsp;s | β^− | ²²²Rn | | |-id=Astatine-223 | ²²³At | style="text-align:right" | 85 | style="text-align:right" | 138 | 223.025151(15) | 50(7)&nbsp;s | β^− | ²²³Rn | 3/2−# | |-id=Astatine-224 | ²²⁴At | style="text-align:right" | 85 | style="text-align:right" | 139 | 224.029749(24) | 2.5 +/- 1.5&nbsp;min | β^− | ²²⁴Rn | 2+# | |-id=Astatine-225 | ²²⁵At | style="text-align:right" | 85 | style="text-align:right" | 140 | 225.03253(32)# | 3#&nbsp;s (>300&nbsp;ns) | β^− ? | ²²⁵Rn | 1/2+# | |-id=Astatine-226 | ²²⁶At | style="text-align:right" | 85 | style="text-align:right" | 141 | 226.03721(32)# | 7#&nbsp;min (>300&nbsp;ns) | β^− ? | ²²⁶Rn | 2+# | |-id=Astatine-227 | ²²⁷At | style="text-align:right" | 85 | style="text-align:right" | 142 | 227.04018(32)# | 5#&nbsp;s (>300&nbsp;ns) | β^− ? | ²²⁷Rn | 1/2+# | |-id=Astatine-228 | ²²⁸At | style="text-align:right" | 85 | style="text-align:right" | 143 | 228.04496(43)# | 1#&nbsp;min (>300&nbsp;ns) | β^− ? | ²²⁸Rn | 3+# | |-id=Astatine-229 | ²²⁹At | style="text-align:right" | 85 | style="text-align:right" | 144 | 229.04819(43)# | 1#&nbsp;s (>300&nbsp;ns) | β^− ? | ²²⁹Rn | 1/2+# |

Alpha decay

Alpha decay energy follows the same trend as for other heavy elements. The lighter astatine isotopes have quite high decay energies, which become lower as more neutrons are added, reaching a minimum at 125 neutrons (astatine-210), even though 126 (astatine-211) is the magic number. The decay energies increase much more steeply, though, on the next two steps, reaching a high at 128 neutrons where the alpha-decay product would have the magic number of 126. Here this is astatine-213, releasing the highest energy and having the shortest life (125 ns) of all the isotopes. The energy then declines again, and alpha lifetimes increase quickly, no long-lived astatine isotope exists; this happens due to the increasing role of beta decay. This decay mode is especially important for astatine: as early as 1950, it was postulated that the element has no beta-stable isotopes (i.e. ones that do not undergo beta decay at all), though nuclear mass measurements reveal that ²¹⁵At is in fact beta-stable, as it has the lowest mass of all isobars with A = 215. A beta decay mode has been found for all other astatine isotopes except for ^212-216At and their isomers. Among other isotopes, if they do not undergo alpha decay: astatine-210 and the lighter isotopes decay by electron capture or positron emission, 211 by electron capture only, and astatine-217 and heavier isotopes undergo β^- decay. Astatine-212, 214, and 216 should be able to decay either way.

See also

Daughter products other than astatine

• Isotopes of radon
• Isotopes of polonium
• Isotopes of bismuth

Notes

References