Isotopes of francium

Main isotopes of francium (₈₇Fr)
α	208At
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 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 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
Nuclide [n 1]	Historic name	Excitation energy[n 4]			Half-life [n 4]	Decay mode [n 5]	Daughter isotope	Spin and parity [n 6][n 4]	Isotopic abundance
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−#
^200mFr		60(110) keV			650(210) ms	IT (rare)	²⁰⁰Fr	10−#
²⁰¹Fr		87	114	201.00386(8)	67(3) ms	α (99%)	¹⁹⁷At	(9/2−)
²⁰¹Fr		87	114	201.00386(8)	67(3) ms	β⁺ (1%)	²⁰¹Rn	(9/2−)
²⁰²Fr		87	115	202.00337(5)	290(30) ms	α (97%)	¹⁹⁸At	(3+)
²⁰²Fr		87	115	202.00337(5)	290(30) ms	β⁺ (3%)	²⁰²Rn	(3+)
^202mFr		330(90)# keV			340(40) ms	α (97%)	¹⁹⁸At	(10−)
^202mFr		330(90)# keV			340(40) ms	β⁺ (3%)	²⁰²Rn	(10−)
²⁰³Fr		87	116	203.000925(17)	0.55(2) s	α (95%)	¹⁹⁹At	(9/2−)#
²⁰³Fr		87	116	203.000925(17)	0.55(2) s	β⁺ (5%)	²⁰³Rn	(9/2−)#
²⁰⁴Fr		87	117	204.000653(26)	1.7(3) s	α (96%)	²⁰⁰At	(3+)
²⁰⁴Fr		87	117	204.000653(26)	1.7(3) s	β⁺ (4%)	²⁰⁴Rn	(3+)
^204m1Fr		50(4) keV			2.6(3) s	α (90%)	²⁰⁰At	(7+)
^204m1Fr		50(4) keV			2.6(3) s	β⁺ (10%)	²⁰⁴Rn	(7+)
^204m2Fr		326(4) keV			1.7(6) s			(10−)
²⁰⁵Fr		87	118	204.998594(8)	3.80(3) s	α (99%)	²⁰¹At	(9/2−)
²⁰⁵Fr		87	118	204.998594(8)	3.80(3) s	β⁺ (1%)	²⁰⁵Rn	(9/2−)
²⁰⁶Fr		87	119	205.99867(3)	~16 s	β⁺ (58%)	²⁰⁶Rn	(2+, 3+)
²⁰⁶Fr		87	119	205.99867(3)	~16 s	α (42%)	²⁰²At	(2+, 3+)
^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−
²⁰⁷Fr		87	120	206.99695(5)	14.8(1) s	β⁺ (5%)	²⁰⁷Rn	9/2−
²⁰⁸Fr		87	121	207.99714(5)	59.1(3) s	α (90%)	²⁰⁴At	7+
²⁰⁸Fr		87	121	207.99714(5)	59.1(3) s	β⁺ (10%)	²⁰⁸Rn	7+
²⁰⁹Fr		87	122	208.995954(16)	50.0(3) s	α (89%)	²⁰⁵At	9/2−
²⁰⁹Fr		87	122	208.995954(16)	50.0(3) s	β⁺ (11%)	²⁰⁹Rn	9/2−
²¹⁰Fr		87	123	209.996408(24)	3.18(6) min	α (60%)	²⁰⁶At	6+
²¹⁰Fr		87	123	209.996408(24)	3.18(6) min	β⁺ (40%)	²¹⁰Rn	6+
²¹¹Fr		87	124	210.995537(23)	3.10(2) min	α (80%)	²⁰⁷At	9/2−
²¹¹Fr		87	124	210.995537(23)	3.10(2) min	β⁺ (20%)	²¹¹Rn	9/2−
²¹²Fr		87	125	211.996202(28)	20.0(6) min	β⁺ (57%)	²¹²Rn	5+
²¹²Fr		87	125	211.996202(28)	20.0(6) min	α (43%)	²⁰⁸At	5+
²¹³Fr		87	126	212.996189(8)	34.6(3) s	α (99.45%)	²⁰⁹At	9/2−
²¹³Fr		87	126	212.996189(8)	34.6(3) s	β⁺ (.55%)	²¹³Rn	9/2−
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−)
²¹⁶Fr		87	129	216.003198(15)	0.70(2) µs	β⁺ (2×10⁻⁷%)	²¹⁶Rn	(1−)
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
^218m1Fr		86(4) keV			22.0(5) ms	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+
²²⁰Fr		87	133	220.012327(4)	27.4(3) s	β⁻ (.35%)	²²⁰Ra	1+
²²¹Fr		87	134	221.014255(5)	4.9(2) min	α (99.9%)	²¹⁷At	5/2−	Trace[n 7]
						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 8]
²²³Fr	Actinium K	87	136	223.0197359(26)	22.00(7) min	α (.006%)	²¹⁹At	3/2(−)	Trace[n 8]
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

^mFr – Excited nuclear isomer.
( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
# – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
# – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
Modes of decay:

CD: Cluster decay

IT: Isomeric transition
( ) spin value – Indicates spin with weak assignment arguments.
Intermediate decay product of ²³⁷Np
Intermediate decay product of ²³⁵U

References

Isotope masses from:
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
Isotopic compositions and standard atomic masses from:
- de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

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[1] Fr – Excited nuclear isomer.

[2] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-3] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[TNN-4] # – 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] Intermediate decay product of ²³⁷Np

[8] Intermediate decay product of ²³⁵U

CD:	Cluster decay
IT:	Isomeric transition