钫的同位素
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鍅没有稳定的同位素，因此无法得到其标准原子量，但鍅存在有两个天然放射性同位素。目前已知的有35种鍅的同位素，原子量从199到233，其中最稳定的同位素是鍅-223（223
Fr
），半衰期为22分钟，由于是铀-235（235
U
）的衰变产物，因此在地壳中微量存在，而另一个自然同位素是221
Fr
，半衰期较短，只有4.9分钟，目前已知稳定性最差的鍅同位素是215
Fr
，半衰期为86奈秒。
钫在前105个元素之中最不稳定。106号元素𬭳和之后的元素虽然比钫更不稳定，但因为目前发现的同位素数量不多，所以以后可能会发现更长寿的同位素。
图表
| 符号 | 历史 名称 |
Z | N | 同位素质量（u） [n 1][n 2] |
半衰期 [n 2] |
衰变 方式[1] |
衰变 产物 |
原子核 自旋[n 1] |
相对丰度 （莫耳分率） |
|---|---|---|---|---|---|---|---|---|---|
| 激发能量[n 1][n 2] | |||||||||
| 199Fr | 87 | 112 | 199.00726(4) | 16(7) ms | 1/2+# | ||||
| 200Fr | 87 | 113 | 200.00657(8) | 24(10) ms | α | 196At | 3+# | ||
| 200mFr | 60(110) keV | 650(210) ms | α | 196At | 10−# | ||||
| IT （不常见） | 200Fr | ||||||||
| 201Fr | 87 | 114 | 201.00386(8) | 67(3) ms | α (99%) | 197At | (9/2−) | ||
| β+ (1%) | 201Rn | ||||||||
| 202Fr | 87 | 115 | 202.00337(5) | 290(30) ms | α (97%) | 198At | (3+) | ||
| β+ (3%) | 202Rn | ||||||||
| 202mFr | 330(90)# keV | 340(40) ms | α (97%) | 198At | (10−) | ||||
| β+ (3%) | 202Rn | ||||||||
| 203Fr | 87 | 116 | 203.000925(17) | 0.55(2) s | α (95%) | 199At | (9/2−)# | ||
| β+ (5%) | 203Rn | ||||||||
| 204Fr | 87 | 117 | 204.000653(26) | 1.7(3) s | α (96%) | 200At | (3+) | ||
| β+ (4%) | 204Rn | ||||||||
| 204m1Fr | 50(4) keV | 2.6(3) s | α (90%) | 200At | (7+) | ||||
| β+ (10%) | 204Rn | ||||||||
| 204m2Fr | 326(4) keV | 1.7(6) s | (10−) | ||||||
| 205Fr | 87 | 118 | 204.998594(8) | 3.80(3) s | α (99%) | 201At | (9/2−) | ||
| β+ (1%) | 205Rn | ||||||||
| 206Fr | 87 | 119 | 205.99867(3) | ~16 s | β+ (58%) | 206Rn | (2+,3+) | ||
| α (42%) | 202At | ||||||||
| 206m1Fr | 190(40) keV | 15.9(1) s | (7+) | ||||||
| 206m2Fr | 730(40) keV | 700(100) ms | (10−) | ||||||
| 207Fr | 87 | 120 | 206.99695(5) | 14.8(1) s | α (95%) | 203At | 9/2− | ||
| β+ (5%) | 207Rn | ||||||||
| 208Fr | 87 | 121 | 207.99714(5) | 59.1(3) s | α (90%) | 204At | 7+ | ||
| β+ (10%) | 208Rn | ||||||||
| 209Fr | 87 | 122 | 208.995954(16) | 50.0(3) s | α (89%) | 205At | 9/2− | ||
| β+ (11%) | 209Rn | ||||||||
| 210Fr | 87 | 123 | 209.996408(24) | 3.18(6) min | α (60%) | 206At | 6+ | ||
| β+ (40%) | 210Rn | ||||||||
| 211Fr | 87 | 124 | 210.995537(23) | 3.10(2) min | α (80%) | 207At | 9/2− | ||
| β+ (20%) | 211Rn | ||||||||
| 212Fr | 87 | 125 | 211.996202(28) | 20.0(6) min | β+ (57%) | 212Rn | 5+ | ||
| α (43%) | 208At | ||||||||
| 213Fr | 87 | 126 | 212.996189(8) | 34.6(3) s | α (99.45%) | 209At | 9/2− | ||
| β+ (.55%) | 213Rn | ||||||||
| 214Fr | 87 | 127 | 213.998971(9) | 5.0(2) ms | α | 210At | (1−) | ||
| 214m1Fr | 123(6) keV | 3.35(5) ms | α | 210At | (8−) | ||||
| 214m2Fr | 638(6) keV | 103(4) ns | (11+) | ||||||
| 214m3Fr | 6477+Y keV | 108(7) ns | (33+) | ||||||
| 215Fr | 87 | 128 | 215.000341(8) | 86(5) ns | α | 211At | 9/2− | ||
| 216Fr | 87 | 129 | 216.003198(15) | 0.70(2) µs | α | 212At | (1−) | ||
| β+ (2×10−7%) | 216Rn | ||||||||
| 217Fr | 87 | 130 | 217.004632(7) | 16.8(19) µs | α | 213At | 9/2− | ||
| 218Fr | 87 | 131 | 218.007578(5) | 1.0(6) ms | α | 214At | 1− | ||
| 218m1Fr | 86(4) keV | 22.0(5) ms | α | 214At | |||||
| IT （不常见） | 218Fr | ||||||||
| 218m2Fr | 200(150)# keV | high | |||||||
| 219Fr | 87 | 132 | 219.009252(8) | 20(2) ms | α | 215At | 9/2− | ||
| 220Fr | 87 | 133 | 220.012327(4) | 27.4(3) s | α (99.65%) | 216At | 1+ | ||
| β− (.35%) | 220Ra | ||||||||
| 221Fr | 87 | 134 | 221.014255(5) | 4.9(2) min | α (99.9%) | 217At | 5/2− | Trace[n 3] | |
| β− (.1%) | 221Ra | ||||||||
| CD (8.79×10−11%) | 207Tl 14 C | ||||||||
| 222Fr | 87 | 135 | 222.017552(23) | 14.2(3) min | β− | 222Ra | 2− | ||
| 223Fr | Actinium K | 87 | 136 | 223.0197359(26) | 22.00(7) min | β− (99.99%) | 223Ra | 3/2(−) | Trace[n 4] |
| α (.006%) | 219At | ||||||||
| 224Fr | 87 | 137 | 224.02325(5) | 3.33(10) min | β− | 224Ra | 1− | ||
| 225Fr | 87 | 138 | 225.02557(3) | 4.0(2) min | β− | 225Ra | 3/2− | ||
| 226Fr | 87 | 139 | 226.02939(11) | 49(1) s | β− | 226Ra | 1− | ||
| 227Fr | 87 | 140 | 227.03184(11) | 2.47(3) min | β− | 227Ra | 1/2+ | ||
| 228Fr | 87 | 141 | 228.03573(22)# | 38(1) s | β− | 228Ra | 2− | ||
| 229Fr | 87 | 142 | 229.03845(4) | 50.2(4) s | β− | 229Ra | (1/2+)# | ||
| 230Fr | 87 | 143 | 230.04251(48)# | 19.1(5) s | β− | 230Ra | |||
| 231Fr | 87 | 144 | 231.04544(50)# | 17.6(6) s | β− | 231Ra | (1/2+)# | ||
| 232Fr | 87 | 145 | 232.04977(69)# | 5(1) s | β− | 232Ra | |||
| 233Fr | 87 | 146 | 233.052518(21) | 900(100) ms | β− | 233Ra | 1/2+ # | ||
- ^ 1.0 1.1 1.2 画上#号的数据代表没有经过实验的证明，仅为理论推测。
- ^ 2.0 2.1 2.2 用括号括起来的数据代表不确定性。
- ^ Intermediate decay product of 237Np
- ^ Intermediate decay product of 235U
| ← | 同位素列表 | → |
| 氡的同位素 | 鍅的同位素 | 镭的同位素 |
参考文献
- ^ Universal Nuclide Chart
. nucleonica. [2015-11-01]. （原始内容存档于2017-02-19） （英语）.
- Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
- Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
- Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties （页面存档备份，存于互联网档案馆）, Nuc. Phys. A 729, pp. 3-128 (2003).
- National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database （页面存档备份，存于互联网档案馆） (retrieved Sept. 2005).
- David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.