Isotopes of radium

From Wikipedia, the free encyclopedia

Radium (Ra) has no stable isotopes. A standard atomic mass cannot be given.

Isotopes of radium occurring within the radioactive disintegration chains of actinium and thorium were known as:

  • actinium X : 223Ra
  • thorium X : 224Ra
  • mesothorium I : 228Ra

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
202Ra 88 114 202.00989(7) 2.6(21) ms [0.7(+33-3) ms] 0+
203Ra 88 115 203.00927(9) 4(3) ms (3/2-)
203mRa 220(90) keV 41(17) ms (13/2+)
204Ra 88 116 204.006500(17) 60(11) ms [59(+12-9) ms] 0+
205Ra 88 117 205.00627(9) 220(40) ms [210(+60-40) ms] (3/2-)
205mRa 310(110)# keV 180(50) ms [170(+60-40) ms] (13/2+)
206Ra 88 118 206.003827(19) 0.24(2) s 0+
207Ra 88 119 207.00380(6) 1.3(2) s (5/2-,3/2-)
207mRa 560(50) keV 57(8) ms (13/2+)
208Ra 88 120 208.001840(17) 1.3(2) s 0+
208mRa 1800(200) keV 270 ns (8+)
209Ra 88 121 209.00199(5) 4.6(2) s 5/2-
210Ra 88 122 210.000495(16) 3.7(2) s 0+
210mRa 1800(200) keV 2.24 µs (8+)
211Ra 88 123 211.000898(28) 13(2) s 5/2(-)
212Ra 88 124 211.999794(12) 13.0(2) s 0+
212m1Ra 1958.4(5) keV 10.9(4) µs (8)+
212m2Ra 2613.4(5) keV 0.85(13) µs (11)-
213Ra 88 125 213.000384(22) 2.74(6) min 1/2-
213mRa 1769(6) keV 2.1(1) ms 17/2-#
214Ra 88 126 214.000108(10) 2.46(3) s 0+
215Ra 88 127 215.002720(8) 1.55(7) ms (9/2+)#
215m1Ra 1877.8(5) keV 7.1(2) µs (25/2+)
215m2Ra 2246.9(5) keV 1.39(7) µs (29/2-)
215m3Ra 3756.6(6)+X keV 0.555(10) µs (43/2-)
216Ra 88 128 216.003533(9) 182(10) ns 0+
217Ra 88 129 217.006320(9) 1.63(17) µs (9/2+)
218Ra 88 130 218.007140(12) 25.2(3) µs 0+
219Ra 88 131 219.010085(9) 10(3) ms (7/2)+
220Ra 88 132 220.011028(10) 17.9(14) ms 0+
221Ra 88 133 221.013917(5) 28(2) s 5/2+
222Ra 88 134 222.015375(5) 38.0(5) s 0+
223Ra 88 135 223.0185022(27) 11.43(5) d 3/2+
224Ra 88 136 224.0202118(24) 3.6319(23) d 0+
225Ra 88 137 225.023612(3) 14.9(2) d 1/2+
226Ra 88 138 226.0254098(25) 1600(7) a 0+
227Ra 88 139 227.0291778(25) 42.2(5) min 3/2+
228Ra 88 140 228.0310703(26) 5.75(3) a 0+
229Ra 88 141 229.034958(20) 4.0(2) min 5/2(+)
230Ra 88 142 230.037056(13) 93(2) min 0+
231Ra 88 143 231.04122(32)# 103(3) s (5/2+)
231mRa 66.21(9) keV ~53 µs (1/2+)
232Ra 88 144 232.04364(30)# 250(50) s 0+
233Ra 88 145 233.04806(50)# 30(5) s 1/2+#
234Ra 88 146 234.05070(53)# 30(10) s 0+

  • 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.


Isotopes of francium Isotopes of radium Isotopes of actinium
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