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Nuclides with atomic number of 89 but with different mass numbers From Wikipedia, the free encyclopedia
Actinium (89Ac) has no stable isotopes and no characteristic terrestrial isotopic composition, thus a standard atomic weight cannot be given. There are 34 known isotopes, from 203Ac to 236Ac, and 7 isomers. Three isotopes are found in nature, 225Ac, 227Ac and 228Ac, as intermediate decay products of, respectively, 237Np, 235U, and 232Th. 228Ac and 225Ac are extremely rare, so 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.
Purified 227Ac comes into equilibrium with its decay products (227Th and 223Fr) after 185 days.[2]
Nuclide [n 1] |
Historic name |
Z | N | Isotopic mass (Da) [n 2][n 3] |
Half-life |
Decay mode [n 4] |
Daughter isotope [n 5] |
Spin and parity [n 6][n 7] |
Isotopic abundance | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Excitation energy[n 7] | |||||||||||||||||||
203Ac[3] | 89 | 114 | 56+269 −26 μs |
α | 199Fr | (1/2+) | |||||||||||||
204Ac[4] | 89 | 115 | 7.4+2.2 −1.4 ms |
α | 200Fr | ||||||||||||||
205Ac[5] | 89 | 116 | 7.7+2.7 −1.6 ms[4] |
α | 201Fr | 9/2−? | |||||||||||||
206Ac | 89 | 117 | 206.01450(8) | 25(7) ms | α | 202Fr | (3+) | ||||||||||||
206m1Ac | 80(50) keV | 15(6) ms | α | 202Fr | |||||||||||||||
206m2Ac | 290(110)# keV | 41(16) ms | α | 202mFr | (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 | α | 212Fr | (9−) | ||||||||||||||
217Ac | 89 | 128 | 217.009347(14) | 69(4) ns | α | 213Fr | 9/2− | ||||||||||||
β+ (6.9×10−9%) | 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 8] | 89 | 136 | 225.023230(5) | 10.0(1) d | α | 221Fr | (3/2−) | Trace[n 9] | |||||||||||
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 10] | 89 | 138 | 227.0277521(26) | 21.772(3) y | β− (98.62%) | 227Th | 3/2− | Trace[n 11] | ||||||||||
α (1.38%) | 223Fr | ||||||||||||||||||
228Ac | Mesothorium 2 | 89 | 139 | 228.0310211(27) | 6.13(2) h | β− | 228Th | 3+ | Trace[n 12] | ||||||||||
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)# | 60(4) s | β− | 235Th | 1/2+# | ||||||||||||
236Ac[6] | 89 | 147 | 236.05530(54)# | 72+345 −33 s |
β− | 236Th | |||||||||||||
This table header & footer: |
CD: | Cluster decay |
EC: | Electron capture |
IT: | Isomeric transition |
Actinides[7] by decay chain | Half-life range (a) |
Fission products of 235U by yield[8] | ||||||
---|---|---|---|---|---|---|---|---|
4n | 4n + 1 | 4n + 2 | 4n + 3 | 4.5–7% | 0.04–1.25% | <0.001% | ||
228Ra№ | 4–6 a | 155Euþ | ||||||
248Bk[9] | > 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[10] | 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₡ | |||||
1.53 Ma | 93Zr | |||||||
237Npƒ | 2.1–6.5 Ma | 135Cs₡ | 107Pd | |||||
236U | 247Cmƒ | 15–24 Ma | 129I₡ | |||||
244Pu | 80 Ma |
... nor beyond 15.7 Ma[11] | ||||||
232Th№ | 238U№ | 235Uƒ№ | 0.7–14.1 Ga | |||||
|
Actinium-225 is a highly radioactive isotope with 136 neutrons. It is an alpha emitter and has a half-life of 9.919 days. As of 2024, it is being researched as a possible alpha source in targeted alpha therapy.[12][13][14] Actinium-225 undergoes a series of three alpha decays – via the short-lived francium-221 and astatine-217 – to 213Bi, which itself is used as an alpha source.[15] Another benefit is that the decay chain of 225Ac ends in the nuclide 209Bi,[note 1] which has a considerably shorter biological half-life than lead.[16][17] However, a major factor limiting its usage is the difficulty in producing the short-lived isotope, as it is most commonly isolated from aging parent nuclides (such as 233U); it may also be produced in cyclotrons, linear accelerators, or fast breeder reactors.[18]
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