Isotopes of astatine

Astatine (At) has 37 known isotopes, all of which are radioactive; the range of their mass numbers is from 191 to 229. There exist also 23 metastable excited states. The longest-lived isotope is 210At, which has a half-life of 8.1 hours; the longest-lived isotope existing in naturally occurring decay chains is 219At with a half-life of 56 seconds.

Contents

Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life decay
mode(s)[1][n 1]
daughter
isotope(s)
nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
191At 85 106 1.7(+11-5) ms (1/2+)
191mAt 2.1(+4-3) ms (7/2-)
193At 85 108 192.99984(6) 28(+5-4) ms α 189Bi (1/2+)
193m1At 50 keV 21(5) ms (7/2-)
193m2At 39 keV 27(+4-5) ms (13/2+)
194At 85 109 193.99873(20) ~40 ms α 190Bi 3+#
β+ (rare) 194Po
194mAt 480(190) keV ~250 ms α 190Bi 10-#
IT (rare) 194At
195At 85 110 194.996268(10) 328(20) ms α (75%) 191Bi (1/2+)
β+ (25%) 195Po
195mAt 34(7) keV 147(5) ms 9/2-#
196At 85 111 195.99579(6) 253(9) ms α (96%) 192Bi 3+#
β+ (4%) 196Po
196m1At -30(80) keV 20# ms 10-#
196m2At 157.9(1) keV 11 µs 5+#
197At 85 112 196.99319(5) 0.390(16) s α (96%) 193Bi (9/2-)
β+ (4%) 197Po
197mAt 52(10) keV 2.0(2) s (1/2+)
198At 85 113 197.99284(5) 4.2(3) s α (94%) 194Bi (3+)
β+ (6%) 198Po
198mAt 330(90)# keV 1.0(2) s (10-)
199At 85 114 198.99053(5) 6.92(13) s α (89%) 195Bi (9/2-)
β+ (11%) 199Po
200At 85 115 199.990351(26) 43.2(9) s α (57%) 196Bi (3+)
β+ (43%) 200Po
200m1At 112.7(30) keV 47(1) s α (43%) 196Bi (7+)
IT 200At
β+ 200Po
200m2At 344(3) keV 3.5(2) s (10-)
201At 85 116 200.988417(9) 85(3) s α (71%) 197Bi (9/2-)
β+ (29%) 201Po
202At 85 117 201.98863(3) 184(1) s β+ (88%) 202Po (2,3)+
α (12%) 198Bi
202m1At 190(40) keV 182(2) s (7+)
202m2At 580(40) keV 460(50) ms (10-)
203At 85 118 202.986942(13) 7.37(13) min β+ (69%) 203Po 9/2-
α (31%) 199Bi
204At 85 119 203.987251(26) 9.2(2) min β+ (96.2%) 204Po 7+
α (3.8%) 200Bi
204mAt 587.30(20) keV 108(10) ms IT 204At (10-)
205At 85 120 204.986074(16) 26.2(5) min β+ (90%) 205Po 9/2-
α (10%) 201Bi
205mAt 2339.65(23) keV 7.76(14) µs 29/2+
206At 85 121 205.986667(22) 30.6(13) min β+ (99.11%) 206Po (5)+
α (.89%) 202Bi
206mAt 807(3) keV 410(80) ns (10)-
207At 85 122 206.985784(23) 1.80(4) h β+ (91.4%) 207Po 9/2-
α (8.6%) 203Bi
208At 85 123 207.986590(28) 1.63(3) h β+ (99.45%) 208Po 6+
α (.55%) 204Bi
209At 85 124 208.986173(8) 5.41(5) h β+ (95.9%) 209Po 9/2-
α (4.1%) 205Bi
210At 85 125 209.987148(8) 8.1(4) h β+ (99.82%) 210Po (5)+
α (.175%) 206Bi
210m1At 2549.6(2) keV 482(6) µs (15)-
210m2At 4027.7(2) keV 5.66(7) µs (19)+
211At 85 126 210.9874963(30) 7.214(7) h EC (58.2%) 211Po 9/2-
α (41.8%) 207Bi
212At 85 127 211.990745(8) 0.314(2) s α (99.97%) 208Bi (1-)
β+ (.03%) 212Po
β- (2×10−6%) 212Rn
212m1At 223(7) keV 0.119(3) s α (99%) 208Bi (9-)
IT (1%) 212At
212m2At 4771.6(11) keV 152(5) µs (25-)
213At 85 128 212.992937(5) 125(6) ns α 209Bi 9/2-
214At 85 129 213.996372(5) 558(10) ns α 210Bi 1-
214m1At 59(9) keV 265(30) ns
214m2At 231(6) keV 760(15) ns 9-
215At 85 130 214.998653(7) 0.10(2) ms α 211Bi 9/2- Trace[n 2]
216At 85 131 216.002423(4) 0.30(3) ms α (99.99%) 212Bi 1-
β- (.006%) 216Rn
EC (3×10−7%) 216Po
216mAt 413(5) keV 100# µs (9-)
217At 85 132 217.004719(5) 32.3(4) ms α (99.98%) 213Bi 9/2-
β- (.012%) 217Rn
218At 85 133 218.008694(12) 1.5(3) s α (99.9%) 214Bi 1-# Trace[n 3]
β- (.1%) 218Rn
219At 85 134 219.011162(4) 56(3) s α (97%) 215Bi 5/2-# Trace[n 2]
β- (3%) 219Rn
220At 85 135 220.01541(6) 3.71(4) min β- (92%) 220Rn 3(-#)
α (8%) 216Bi
221At 85 136 221.01805(21)# 2.3(2) min β- 221Rn 3/2-#
222At 85 137 222.02233(32)# 54(10) s β- 222Rn
223At 85 138 223.02519(43)# 50(7) s 3/2-#
  1. ^ Abbreviations:
    EC: Electron capture
    IT: Isomeric transition
  2. ^ a b Intermediate decay product of 235U
  3. ^ Intermediate decay product of 238U

Notes

See also


References

  1. ^ http://www.nucleonica.net/unc.aspx
Isotopes of polonium Isotopes of astatine Isotopes of radon
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