钫的同位素
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钫没有稳定的同位素,因此无法得到其标准原子量,但钫存在有两个天然放射性同位素。目前已知的有35种钫的同位素,原子量从199到233,其中最稳定的同位素是钫-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钫同位素是215
Fr
,半衰期为86纳秒。
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[编辑]
符号 | 历史 名称 |
Z( p ) |
N( n ) |
同位素质量(u) | 半衰期[n 1] | 衰变 方式[1][n 2] |
衰变 产物 |
原子核 自旋 |
相对丰度 (摩尔分率) |
---|---|---|---|---|---|---|---|---|---|
激发能量 | |||||||||
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+ # |
备注:画上#号的数据代表没有经过实验的证明,只是理论推测而已,而用括号括起来的代表数据不确定性。
← | 同位素列表 | → |
氡的同位素 | 钫的同位素 | 镭的同位素 |
注释[编辑]
- ^ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
- ^ Abbreviations:
CD: Cluster decay
IT: 核异构转变 - ^ Intermediate decay product of 237Np
- ^ Intermediate decay product of 235U
参考文献[编辑]
- ^ 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.
元素与同位素的稳定度 | |||||||||||||||||||||||||||||||||
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