Isotopes of francium

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Isotopes of francium  (87Fr)
Main isotopes [1] Decay
abun­dance half-life (t1/2) mode pro­duct
212Fr synth 20.0 min β+ 212Rn
α 208At
221Fr trace 4.8 min α 217At
222Frsynth14.2 min β− 222Ra
223Frtrace22.00 minβ− 223Ra
α 219At

Francium (87Fr) has no stable isotopes. A standard atomic weight cannot be given. Its most stable isotope is 223Fr with a half-life of 22 minutes, occurring in trace quantities in nature as an intermediate decay product of 235U.

Of elements whose most stable isotopes have been identified with certainty, francium is the most unstable. All elements with atomic number of 106 (seaborgium) or greater have most-stable-known isotopes shorter than that of francium, but as those elements have only a relatively small number of isotopes discovered, the possibility remains that undiscovered isotopes of these elements may have longer half-lives.

List of isotopes


Nuclide
[n 1] 		Historic
name		 Z N Isotopic mass (Da)
[n 2] [n 3] 		Half-life
[n 4] 		Decay
mode
[n 5] 		Daughter
isotope
Spin and
parity
[n 6] [n 4] 		Isotopic
abundance
Excitation energy [n 4]
197Fr87110197.01101(6)2.3(19) ms α 193At(7/2−)
198Fr87111198.01028(3)15(3) msα194At3+#
199Fr87112199.00726(4)16(7) msα195At1/2+#
200Fr87113200.00657(8)24(10) msα196At3+#
200mFr60(110) keV190(120) msα196At10−#
201Fr87114201.00386(8)67(3) msα (99%)197At(9/2−)
β+ (1%)201Rn
202Fr87115202.00337(5)290(30) msα (97%)198At(3+)
β+ (3%)202Rn
202mFr330(90)# keV340(40) msα (97%)198At(10−)
β+ (3%)202Rn
203Fr87116203.000925(17)0.55(2) sα (95%)199At(9/2−)#
β+ (5%)203Rn
204Fr87117204.000653(26)1.7(3) sα (96%)200At(3+)
β+ (4%)204Rn
204m1Fr50(4) keV2.6(3) sα (90%)200At(7+)
β+ (10%)204Rn
204m2Fr326(4) keV1.7(6) s(10−)
205Fr87118204.998594(8)3.80(3) sα (99%)201At(9/2−)
β+ (1%)205Rn
206Fr87119205.99867(3)~16 sβ+ (58%)206Rn(2+, 3+)
α (42%)202At
206m1Fr190(40) keV15.9(1) s(7+)
206m2Fr730(40) keV700(100) ms(10−)
207Fr87120206.99695(5)14.8(1) sα (95%)203At9/2−
β+ (5%)207Rn
208Fr87121207.99714(5)59.1(3) sα (90%)204At7+
β+ (10%)208Rn
209Fr87122208.995954(16)50.0(3) sα (89%)205At9/2−
β+ (11%)209Rn
210Fr87123209.996408(24)3.18(6) minα (60%)206At6+
β+ (40%)210Rn
211Fr87124210.995537(23)3.10(2) minα (80%)207At9/2−
β+ (20%)211Rn
212Fr87125211.996202(28)20.0(6) minβ+ (57%)212Rn5+
α (43%)208At
213Fr87126212.996189(8)34.14(6) s [2] α (99.45%)209At9/2−
β+ (.55%)213Rn
214Fr87127213.998971(9)5.0(2) msα210At(1−)
214m1Fr123(6) keV3.35(5) msα210At(8−)
214m2Fr638(6) keV103(4) ns(11+)
214m3Fr6477+Y keV108(7) ns(33+)
215Fr87128215.000341(8)86(5) nsα211At9/2−
216Fr87129216.003198(15)0.70(2) μsα212At(1−)
216mFr219(6) keV850(30) nsα [n 7] 212At(9−)
217Fr87130217.004632(7)16.8(19) μsα213At9/2−
218Fr87131218.007578(5)1.0(6) msα214At1−
218m1Fr86(4) keV22.0(5) msα214At(8−)
218m2Fr200(150)# keVhigh
219Fr87132219.009252(8)20(2) msα215At9/2−
220Fr87133220.012327(4)27.4(3) sα (99.65%)216At1+
β− (.35%)220Ra
221Fr87134221.014255(5)4.9(2) minα (99.9%)217At5/2−Trace [n 8]
β− (.1%)221Ra
CD (8.79×10−11%) [n 9] 207Tl
14C
222Fr87135222.017552(23)14.2(3) minβ−222Ra2−
223FrActinium K87136223.0197359(26)22.00(7) minβ− (99.99%)223Ra3/2(−)Trace [n 10]
α (.006%)219At
224Fr87137224.02325(5)3.33(10) minβ−224Ra1−
225Fr87138225.02557(3)4.0(2) minβ−225Ra3/2−
226Fr87139226.02939(11)49(1) sβ−226Ra1−
227Fr87140227.03184(11)2.47(3) minβ−227Ra1/2+
228Fr87141228.03573(22)#38(1) sβ−228Ra2−
229Fr87142229.03845(4)50.2(4) sβ−229Ra(1/2+)#
230Fr87143230.04251(48)#19.1(5) sβ−230Ra
231Fr87144231.04544(50)#17.6(6) sβ−231Ra(1/2+)#
232Fr87145232.04977(69)#5(1) sβ−232Ra
233Fr87146233.052518(21)900(100) msβ−233Ra1/2+ #
This table header & footer:
  1. ↑ mFr – Excited nuclear isomer.
  2. ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. 1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. ↑ Modes of decay:
    CD: Cluster decay
    IT: Isomeric transition
  6. ↑ ( ) spin value – Indicates spin with weak assignment arguments.
  7. ↑ Theoretically capable of β+ decay to 216Rn [1]
  8. ↑ Intermediate decay product of 237Np
  9. ↑ The nuclide with the lowest atomic number known to undergo cluster decay
  10. ↑ Intermediate decay product of 235U

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References

  1. 1 2 Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  2. ↑ Fisichella, M.; Musumarra, A.; Farinon, F.; Nociforo, C.; Del Zoppo, A.; Figuera, P.; La Cognata, M.; Pellegriti, M. G.; Scuderi, V.; Torresi, D.; Strano, E. (2013-07-24). "Determination of the half-life of 213Fr with high precision". Physical Review C. 88 (1). American Physical Society (APS): 011303. Bibcode:2013PhRvC..88a1303F. doi:10.1103/physrevc.88.011303. ISSN   0556-2813.
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