Isotopes of francium

From Wikipedia, the free encyclopedia
Jump to: navigation, search

Francium (Fr) has no stable isotopes. A standard atomic mass cannot be given. Its most stable isotope is 223Fr with a half-life of 22 minutes, occurring in trace quantities as an intermediate decay product of 235U. The other natural isotope is 221Fr.

Of elements whose most stable isotopes have been identified with certainty, Francium is the most unstable. All elements with atomic number of greater than or equal to 106 (Seaborgium) have most-stable-known isotopes shorter than that of Francium, but those elements have only a relatively small number of isotopes discovered, thus, there is the possibility of a yet-unknown isotope having a longer half-life.

Table[edit]

nuclide
symbol
historic
name
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
199Fr 87 112 199.00726(4) 16(7) ms 1/2+#
200Fr 87 113 200.00657(8) 24(10) ms α 196At 3+#
200mFr 60(110) keV 650(210) ms α 196At 10-#
IT (rare) 200Fr
201Fr 87 114 201.00386(8) 67(3) ms α (99%) 197At (9/2-)
β+ (1%) 201Rn
202Fr 87 115 202.00337(5) 290(30) ms α (97%) 198At (3+)
β+ (3%) 202Rn
202mFr 330(90)# keV 340(40) ms α (97%) 198At (10-)
β+ (3%) 202Rn
203Fr 87 116 203.000925(17) 0.55(2) s α (95%) 199At (9/2-)#
β+ (5%) 203Rn
204Fr 87 117 204.000653(26) 1.7(3) s α (96%) 200At (3+)
β+ (4%) 204Rn
204m1Fr 50(4) keV 2.6(3) s α (90%) 200At (7+)
β+ (10%) 204Rn
204m2Fr 326(4) keV 1.7(6) s (10-)
205Fr 87 118 204.998594(8) 3.80(3) s α (99%) 201At (9/2-)
β+ (1%) 205Rn
206Fr 87 119 205.99867(3) ~16 s β+ (58%) 206Rn (2+,3+)
α (42%) 202At
206m1Fr 190(40) keV 15.9(1) s (7+)
206m2Fr 730(40) keV 700(100) ms (10-)
207Fr 87 120 206.99695(5) 14.8(1) s α (95%) 203At 9/2-
β+ (5%) 207Rn
208Fr 87 121 207.99714(5) 59.1(3) s α (90%) 204At 7+
β+ (10%) 208Rn
209Fr 87 122 208.995954(16) 50.0(3) s α (89%) 205At 9/2-
β+ (11%) 209Rn
210Fr 87 123 209.996408(24) 3.18(6) min α (60%) 206At 6+
β+ (40%) 210Rn
211Fr 87 124 210.995537(23) 3.10(2) min α (80%) 207At 9/2-
β+ (20%) 211Rn
212Fr 87 125 211.996202(28) 20.0(6) min β+ (57%) 212Rn 5+
α (43%) 208At
213Fr 87 126 212.996189(8) 34.6(3) s α (99.45%) 209At 9/2-
β+ (.55%) 213Rn
214Fr 87 127 213.998971(9) 5.0(2) ms α 210At (1-)
214m1Fr 123(6) keV 3.35(5) ms α 210At (8-)
214m2Fr 638(6) keV 103(4) ns (11+)
214m3Fr 6477+Y keV 108(7) ns (33+)
215Fr 87 128 215.000341(8) 86(5) ns α 211At 9/2-
216Fr 87 129 216.003198(15) 0.70(2) µs α 212At (1-)
β+ (2×10−7%) 216Rn
217Fr 87 130 217.004632(7) 16.8(19) µs α 213At 9/2-
218Fr 87 131 218.007578(5) 1.0(6) ms α 214At 1-
218m1Fr 86(4) keV 22.0(5) ms α 214At
IT (rare) 218Fr
218m2Fr 200(150)# keV high
219Fr 87 132 219.009252(8) 20(2) ms α 215At 9/2-
220Fr 87 133 220.012327(4) 27.4(3) s α (99.65%) 216At 1+
β- (.35%) 220Ra
221Fr 87 134 221.014255(5) 4.9(2) min α (99.9%) 217At 5/2- Trace[n 2]
β- (.1%) 221Ra
CD (8.79×10−11%) 207Tl
14C
222Fr 87 135 222.017552(23) 14.2(3) min β- 222Ra 2-
223Fr Actinium K 87 136 223.0197359(26) 22.00(7) min β- (99.99%) 223Ra 3/2(-) Trace[n 3]
α (.006%) 219At
224Fr 87 137 224.02325(5) 3.33(10) min β- 224Ra 1-
225Fr 87 138 225.02557(3) 4.0(2) min β- 225Ra 3/2-
226Fr 87 139 226.02939(11) 49(1) s β- 226Ra 1-
227Fr 87 140 227.03184(11) 2.47(3) min β- 227Ra 1/2+
228Fr 87 141 228.03573(22)# 38(1) s β- 228Ra 2-
229Fr 87 142 229.03845(4) 50.2(4) s β- 229Ra (1/2+)#
230Fr 87 143 230.04251(48)# 19.1(5) s β- 230Ra
231Fr 87 144 231.04544(50)# 17.6(6) s β- 231Ra (1/2+)#
232Fr 87 145 232.04977(69)# 5(1) s β- 232Ra
  1. ^ Abbreviations:
    CD: Cluster decay
    IT: Isomeric transition
  2. ^ Intermediate decay product of 237Np
  3. ^ Intermediate decay product of 235U

Notes[edit]

  • 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.

References[edit]

  1. ^ http://www.nucleonica.net/unc.aspx


Isotopes of radon Isotopes of francium Isotopes of radium
Table of nuclides