Isotopes of actinium

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Actinium (Ac) has no stable isotopes. A standard atomic mass cannot be given.

An isotope of actinium occurring within the radioactive disintegration chain of thorium was known as:

  • mesothorium II : 228Ac

[edit] Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
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] 9/2-#
208Ac 89 119 208.01155(6) 97(16) ms [95(+24-16) ms] (3+)
208mAc 506(26) keV 28(7) ms [25(+9-5) ms] (10-)
209Ac 89 120 209.00949(5) 92(11) ms (9/2-)
210Ac 89 121 210.00944(6) 350(40) ms 7+#
211Ac 89 122 211.00773(8) 213(25) ms 9/2-#
212Ac 89 123 212.00781(7) 920(50) ms 6+#
213Ac 89 124 213.00661(6) 731(17) ms (9/2-)#
214Ac 89 125 214.006902(24) 8.2(2) s (5+)#
215Ac 89 126 215.006454(23) 0.17(1) s 9/2-
216Ac 89 127 216.008720(29) 0.440(16) ms (1-)
216mAc 44(7) keV 443(7) µs (9-)
217Ac 89 128 217.009347(14) 69(4) ns 9/2-
217mAc 2012(20) keV 740(40) ns (29/2)+
218Ac 89 129 218.01164(5) 1.08(9) µs (1-)#
218mAc 584(50)# keV 103(11) ns (11+)
219Ac 89 130 219.01242(5) 11.8(15) µs 9/2-
220Ac 89 131 220.014763(16) 26.36(19) ms (3-)
221Ac 89 132 221.01559(5) 52(2) ms 9/2-#
222Ac 89 133 222.017844(6) 5.0(5) s 1-
222mAc 200(150)# keV 1.05(7) min high
223Ac 89 134 223.019137(8) 2.10(5) min (5/2-)
224Ac 89 135 224.021723(4) 2.78(17) h 0-
225Ac 89 136 225.023230(5) 10.0(1) d (3/2-)
226Ac 89 137 226.026098(4) 29.37(12) h (1)(-#)
227Ac 89 138 227.0277521(26) 21.772(3) a 3/2-
228Ac 89 139 228.0310211(27) 6.15(2) h 3+
229Ac 89 140 229.03302(4) 62.7(5) min (3/2+)
230Ac 89 141 230.03629(32) 122(3) s (1+)
231Ac 89 142 231.03856(11) 7.5(1) min (1/2+)
232Ac 89 143 232.04203(11) 119(5) s (1+)
233Ac 89 144 233.04455(32)# 145(10) s (1/2+)
234Ac 89 145 234.04842(43)# 44(7) s
235Ac 89 146 235.05123(38)# 40# s 1/2+#
236Ac 89 147 236.05530(54)# 2# min

[edit] 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.

[edit] References


Isotopes of radium Isotopes of actinium Isotopes of thorium
Index to isotope pages