Isotopes of actinium
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Actinium (89Ac) has no stable isotopes and no characteristic terrestrial isotopic composition, thus a standard atomic weight cannot be given. There are 31 known isotopes, from 206Ac to 236Ac, and 2 isomers. Two isotopes are found in nature, 227Ac and 228Ac, as intermediate decay products of, respectively, 235U and 232Th. 228Ac is extremely rare, and almost all natural actinium is 227Ac.
The most stable isotopes are 227Ac with a half-life of 21.772 years, 225Ac with a half-life of 10.0 days, and 226Ac with a half-life of 29.37 hours. All other isotopes have half-lives under 10 hours, and most under a minute. The shortest-lived known isotope is 217Ac with a half-life of 69 ns. Actinium also has two meta states.
Purified 227Ac comes into equilibrium with its decay products (227Th and 223Fr) after 185 days.[2]
Actinides vs fission products
| Actinides[3] by decay chain | Half-life range (a) |
Fission products of 235U by yield[4] | ||||||
|---|---|---|---|---|---|---|---|---|
| 4n | 4n + 1 | 4n + 2 | 4n + 3 | 4.5–7% | 0.04–1.25% | <0.001% | ||
| 228Ra№ | 4–6 a | 155Euþ | ||||||
| 248Bk[5] | > 9 a | |||||||
| 244Cmƒ | 241Puƒ | 250Cf | 227Ac№ | 10–29 a | 90Sr | 85Kr | 113mCdþ | |
| 232Uƒ | 238Puƒ | 243Cmƒ | 29–97 a | 137Cs | 151Smþ | 121mSn | ||
| 249Cfƒ | 242mAmƒ | 141–351 a |
No fission products have a half-life | |||||
| 241Amƒ | 251Cfƒ[6] | 430–900 a | ||||||
| 226Ra№ | 247Bk | 1.3–1.6 ka | ||||||
| 240Pu | 229Th | 246Cmƒ | 243Amƒ | 4.7–7.4 ka | ||||
| 245Cmƒ | 250Cm | 8.3–8.5 ka | ||||||
| 239Puƒ | 24.1 ka | |||||||
| 230Th№ | 231Pa№ | 32–76 ka | ||||||
| 236Npƒ | 233Uƒ | 234U№ | 150–250 ka | 99Tc₡ | 126Sn | |||
| 248Cm | 242Pu | 327–375 ka | 79Se₡ | |||||
| 1.33 Ma | 135Cs₡ | |||||||
| 237Npƒ | 1.61–6.5 Ma | 93Zr | 107Pd | |||||
| 236U | 247Cmƒ | 15–24 Ma | 129I₡ | |||||
| 244Pu | 80 Ma |
... nor beyond 15.7 Ma[7] | ||||||
| 232Th№ | 238U№ | 235Uƒ№ | 0.7–14.1 Ga | |||||
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List of isotopes
| nuclide symbol |
historic name |
Z(p) | N(n) | isotopic mass (u) |
half-life | decay mode(s)[8][n 1] |
daughter isotope(s)[n 2] |
nuclear spin |
representative isotopic composition (mole fraction) |
range of natural variation (mole fraction) |
|---|---|---|---|---|---|---|---|---|---|---|
| excitation energy | ||||||||||
| 205Ac[9] | 89 | 116 | 20(+97−9) ms | α | 201Fr | |||||
| 206Ac | 89 | 117 | 206.01450(8) | 25(7) ms | (3+) | |||||
| 206m1Ac | 80(50) keV | 15(6) ms | ||||||||
| 206m2Ac | 290(110)# keV | 41(16) ms | (10−) | |||||||
| 207Ac | 89 | 118 | 207.01195(6) | 31(8) ms [27(+11−6) ms] |
α | 203Fr | 9/2−# | |||
| 208Ac | 89 | 119 | 208.01155(6) | 97(16) ms [95(+24−16) ms] |
α (99%) | 204Fr | (3+) | |||
| β+ (1%) | 208Ra | |||||||||
| 208mAc | 506(26) keV | 28(7) ms [25(+9−5) ms] |
α (89%) | 204Fr | (10−) | |||||
| IT (10%) | 208Ac | |||||||||
| β+ (1%) | 208Ra | |||||||||
| 209Ac | 89 | 120 | 209.00949(5) | 92(11) ms | α (99%) | 205Fr | (9/2−) | |||
| β+ (1%) | 209Ra | |||||||||
| 210Ac | 89 | 121 | 210.00944(6) | 350(40) ms | α (96%) | 206Fr | 7+# | |||
| β+ (4%) | 210Ra | |||||||||
| 211Ac | 89 | 122 | 211.00773(8) | 213(25) ms | α (99.8%) | 207Fr | 9/2−# | |||
| β+ (.2%) | 211Ra | |||||||||
| 212Ac | 89 | 123 | 212.00781(7) | 920(50) ms | α (97%) | 208Fr | 6+# | |||
| β+ (3%) | 212Ra | |||||||||
| 213Ac | 89 | 124 | 213.00661(6) | 731(17) ms | α | 209Fr | (9/2−)# | |||
| β+ (rare) | 213Ra | |||||||||
| 214Ac | 89 | 125 | 214.006902(24) | 8.2(2) s | α (89%) | 210Fr | (5+)# | |||
| β+ (11%) | 214Ra | |||||||||
| 215Ac | 89 | 126 | 215.006454(23) | 0.17(1) s | α (99.91%) | 211Fr | 9/2− | |||
| β+ (.09%) | 215Ra | |||||||||
| 216Ac | 89 | 127 | 216.008720(29) | 0.440(16) ms | α | 212Fr | (1−) | |||
| β+ (7×10−5%) | 216Ra | |||||||||
| 216mAc | 44(7) keV | 443(7) µs | (9−) | |||||||
| 217Ac | 89 | 128 | 217.009347(14) | 69(4) ns | α (98%) | 213Fr | 9/2− | |||
| β+ (2%) | 217Ra | |||||||||
| 217mAc | 2012(20) keV | 740(40) ns | (29/2)+ | |||||||
| 218Ac | 89 | 129 | 218.01164(5) | 1.08(9) µs | α | 214Fr | (1−)# | |||
| 218mAc | 584(50)# keV | 103(11) ns | (11+) | |||||||
| 219Ac | 89 | 130 | 219.01242(5) | 11.8(15) µs | α | 215Fr | 9/2− | |||
| β+ (10−6%) | 219Ra | |||||||||
| 220Ac | 89 | 131 | 220.014763(16) | 26.36(19) ms | α | 216Fr | (3−) | |||
| β+ (5×10−4%) | 220Ra | |||||||||
| 221Ac | 89 | 132 | 221.01559(5) | 52(2) ms | α | 217Fr | 9/2−# | |||
| 222Ac | 89 | 133 | 222.017844(6) | 5.0(5) s | α (99%) | 218Fr | 1− | |||
| β+ (1%) | 222Ra | |||||||||
| 222mAc | 200(150)# keV | 1.05(7) min | α (88.6%) | 218Fr | high | |||||
| IT (10%) | 222Ac | |||||||||
| β+ (1.4%) | 222Ra | |||||||||
| 223Ac | 89 | 134 | 223.019137(8) | 2.10(5) min | α (99%) | 219Fr | (5/2−) | |||
| EC (1%) | 223Ra | |||||||||
| CD (3.2×10−9%) | 209Bi 14C | |||||||||
| 224Ac | 89 | 135 | 224.021723(4) | 2.78(17) h | β+ (90.9%) | 224Ra | 0− | |||
| α (9.1%) | 220Fr | |||||||||
| β− (1.6%) | 224Th | |||||||||
| 225Ac[n 3] | 89 | 136 | 225.023230(5) | 10.0(1) d | α | 221Fr | (3/2−) | |||
| CD (6×10−10%) | 211Bi 14C | |||||||||
| 226Ac | 89 | 137 | 226.026098(4) | 29.37(12) h | β− (83%) | 226Th | (1)(−#) | |||
| EC (17%) | 226Ra | |||||||||
| α (.006%) | 222Fr | |||||||||
| 227Ac | Actinium[n 4] | 89 | 138 | 227.0277521(26) | 21.772(3) y | β− (98.61%) | 227Th | 3/2− | Trace[n 5] | |
| α (1.38%) | 223Fr | |||||||||
| 228Ac | Mesothorium 2 | 89 | 139 | 228.0310211(27) | 6.13(2) h | β− | 228Th | 3+ | Trace[n 6] | |
| α (5.5×10−6%) | 224Fr | |||||||||
| 229Ac | 89 | 140 | 229.03302(4) | 62.7(5) min | β− | 229Th | (3/2+) | |||
| 230Ac | 89 | 141 | 230.03629(32) | 122(3) s | β− | 230Th | (1+) | |||
| 231Ac | 89 | 142 | 231.03856(11) | 7.5(1) min | β− | 231Th | (1/2+) | |||
| 232Ac | 89 | 143 | 232.04203(11) | 119(5) s | β− | 232Th | (1+) | |||
| 233Ac | 89 | 144 | 233.04455(32)# | 145(10) s | β− | 233Th | (1/2+) | |||
| 234Ac | 89 | 145 | 234.04842(43)# | 44(7) s | β− | 234Th | ||||
| 235Ac | 89 | 146 | 235.05123(38)# | 40# s | β− | 235Th | 1/2+# | |||
| 236Ac | 89 | 147 | 236.05530(54)# | 2# min | β− | 236Th | ||||
- ^ Abbreviations:
CD: Cluster decay
EC: Electron capture
IT: Isomeric transition - ^ Bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
- ^ Has medical uses
- ^ Source of element's name
- ^ Intermediate decay product of 235U
- ^ Intermediate decay product of 232Th
Notes
- Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
- Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.
See also
References
- ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
- ^ G. D. Considine, ed. (2005). "Chemical Elements". Van Nostrand's Encyclopedia of Chemistry. Wiley-Interscience. p. 332. ISBN 978-0-471-61525-5.
- ^ Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
- ^ Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.
- ^ Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
"The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk248 with a half-life greater than 9 [years]. No growth of Cf248 was detected, and a lower limit for the β− half-life can be set at about 104 [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]." - ^ This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
- ^ Excluding those "classically stable" nuclides with half-lives significantly in excess of 232Th; e.g., while 113mCd has a half-life of only fourteen years, that of 113Cd is eight quadrillion years.
- ^ "Universal Nuclide Chart". nucleonica.
{{cite web}}: Unknown parameter|registration=ignored (|url-access=suggested) (help) - ^ Zhang, Z. Y.; Gan, Z. G.; Ma, L.; Yu, L.; Yang, H. B.; Huang, T. H.; Li, G. S.; Tian, Y. L.; Wang, Y. S.; Xu, X. X.; Huang, M. H.; Luo, C.; Ren, Z. Z.; Zhou, S.G.; Zhou, X. H.; Xu, H. S.; Xiao, G. Q. (January 2014). "α decay of the new neutron-deficient isotope 205Ac". Physical Review C. 89 (1): 014308. doi:10.1103/PhysRevC.89.014308.
- Isotope masses from:
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
{{cite journal}}: Unknown parameter|dead-url=ignored (|url-status=suggested) (help)
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
- Isotopic compositions and standard atomic masses from:
- J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051.
{{cite journal}}: Unknown parameter|laysummary=ignored (help)
- Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
{{cite journal}}: Unknown parameter|dead-url=ignored (|url-status=suggested) (help) - National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005.
{{cite web}}: Check date values in:|accessdate=(help) - N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide (ed.). CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0-8493-0485-9.
{{cite book}}: Unknown parameter|nopp=ignored (|no-pp=suggested) (help)
- G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A. 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001. Archived from the original (PDF) on 2008-09-23.
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