Isotopes of francium

Isotopes of francium (₈₇Fr)
α	208At
α	219At
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Francium (₈₇Fr) has no stable isotopes, thus 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)^[2] ^{[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
¹⁹⁷Fr		87	110	197.01101(6)	2.3(19) ms	α	¹⁹³At	(7/2−)
¹⁹⁸Fr		87	111	198.01028(3)	15(3) ms	α	¹⁹⁴At	3+#
¹⁹⁹Fr		87	112	199.007269(15)	16(7) ms	α	¹⁹⁵At	1/2+#
²⁰⁰Fr		87	113	200.00658(3)	24(10) ms	α	¹⁹⁶At	3+#
^200mFr		60(110) keV			190(120) ms	α	¹⁹⁶At	10−#
²⁰¹Fr		87	114	201.003852(10)	67(3) ms	α (99%)	¹⁹⁷At	(9/2−)
²⁰¹Fr		87	114	201.003852(10)	67(3) ms	β⁺ (1%)	²⁰¹Rn	(9/2−)
²⁰²Fr		87	115	202.003330(6)	290(30) ms	α (97%)	¹⁹⁸At	(3+)
²⁰²Fr		87	115	202.003330(6)	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	203.000941(7)	0.55(2) s	α (95%)	¹⁹⁹At	(9/2−)#
²⁰³Fr		87	116	203.000941(7)	0.55(2) s	β⁺ (5%)	²⁰³Rn	(9/2−)#
²⁰⁴Fr		87	117	204.000652(26)	1.7(3) s	α (96%)	²⁰⁰At	(3+)
²⁰⁴Fr		87	117	204.000652(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	205.998661(30)	~16 s	β⁺ (58%)	²⁰⁶Rn	(2+, 3+)
²⁰⁶Fr		87	119	205.998661(30)	~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	206.996941(19)	14.8(1) s	α (95%)	²⁰³At	9/2−
²⁰⁷Fr		87	120	206.996941(19)	14.8(1) s	β⁺ (5%)	²⁰⁷Rn	9/2−
²⁰⁸Fr		87	121	207.997139(13)	59.1(3) s	α (90%)	²⁰⁴At	7+
²⁰⁸Fr		87	121	207.997139(13)	59.1(3) s	β⁺ (10%)	²⁰⁸Rn	7+
²⁰⁹Fr		87	122	208.995940(12)	50.0(3) s	α (89%)	²⁰⁵At	9/2−
²⁰⁹Fr		87	122	208.995940(12)	50.0(3) s	β⁺ (11%)	²⁰⁹Rn	9/2−
²¹⁰Fr		87	123	209.996411(14)	3.18(6) min	α (60%)	²⁰⁶At	6+
²¹⁰Fr		87	123	209.996411(14)	3.18(6) min	β⁺ (40%)	²¹⁰Rn	6+
²¹¹Fr		87	124	210.995555(13)	3.10(2) min	α (80%)	²⁰⁷At	9/2−
²¹¹Fr		87	124	210.995555(13)	3.10(2) min	β⁺ (20%)	²¹¹Rn	9/2−
²¹²Fr		87	125	211.996225(9)	20.0(6) min	β⁺ (57%)	²¹²Rn	5+
²¹²Fr		87	125	211.996225(9)	20.0(6) min	α (43%)	²⁰⁸At	5+
²¹³Fr		87	126	212.996184(5)	34.14(6) s^[3]	α (99.45%)	²⁰⁹At	9/2−
²¹³Fr		87	126	212.996184(5)	34.14(6) s^[3]	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	215.000342(8)	86(5) ns	α	²¹¹At	9/2−
²¹⁶Fr		87	129	216.003190(4)	0.70(2) μs	α	²¹²At	(1−)
^216mFr		219(6) keV			850(30) ns	α^{[n 7]}	²¹²At	(9−)
²¹⁷Fr		87	130	217.004632(7)	16.8(19) μs	α	²¹³At	9/2−
²¹⁸Fr		87	131	218.007579(5)	1.0(6) ms	α	²¹⁴At	1−
^218m1Fr		86(4) keV			22.0(5) ms	α	²¹⁴At	(8−)
^218m2Fr		200(150)# keV						high
²¹⁹Fr		87	132	219.009251(7)	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	221.014254(5)	4.801(5) min	α (99.9%)	²¹⁷At	5/2−	Trace^{[n 8]}
						β⁻ (.1%)	²²¹Ra
						CD (8.79×10⁻¹¹%)^{[n 9]}	²⁰⁷Tl ¹⁴C
²²²Fr		87	135	222.017583(8)	14.2(3) min	β⁻	²²²Ra	2−
²²³Fr	Actinium K	87	136	223.0197342(21)	22.00(7) min	β⁻ (99.99%)	²²³Ra	3/2(−)	Trace^{[n 10]}
²²³Fr	Actinium K	87	136	223.0197342(21)	22.00(7) min	α (.006%)	²¹⁹At	3/2(−)	Trace^{[n 10]}
²²⁴Fr		87	137	224.023348(12)	3.33(10) min	β⁻	²²⁴Ra	1−
²²⁵Fr		87	138	225.025572(13)	4.0(2) min	β⁻	²²⁵Ra	3/2−
²²⁶Fr		87	139	226.029545(7)	49(1) s	β⁻	²²⁶Ra	1−
²²⁷Fr		87	140	227.031865(6)	2.47(3) min	β⁻	²²⁷Ra	1/2+
²²⁸Fr		87	141	228.035839(7)	38(1) s	β⁻	²²⁸Ra	2−
²²⁹Fr		87	142	229.038291(5)	50.2(4) s	β⁻	²²⁹Ra	(1/2+)#
²³⁰Fr		87	143	230.042391(7)	19.1(5) s	β⁻	²³⁰Ra
²³¹Fr		87	144	231.045175(8)	17.6(6) s	β⁻	²³¹Ra	(1/2+)#
²³²Fr		87	145	232.049461(15)	5(1) s	β⁻	²³²Ra
²³³Fr		87	146	233.052518(21)	900(100) ms	β⁻	²³³Ra	1/2+ #
This table header & footer: view

^ ^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).
^ ^a ^b ^c # – 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.
^ Theoretically capable of β⁺ decay to ²¹⁶Rn^[1]
^ Intermediate decay product of ²³⁷Np
^ The nuclide with the lowest atomic number known to undergo cluster decay
^ Intermediate decay product of ²³⁵U

References

^ ^a ^b 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.
^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.
^ 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.

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.

[2] Fr – Excited nuclear isomer.

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

[TMS-5] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[TNN-6] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[7] Modes of decay:

CD: Cluster decay

IT: Isomeric transition

[8] ( ) spin value – Indicates spin with weak assignment arguments.

[10] Theoretically capable of β⁺ decay to ²¹⁶Rn^[1]

[11] Intermediate decay product of ²³⁷Np

[12] The nuclide with the lowest atomic number known to undergo cluster decay

[13] Intermediate decay product of ²³⁵U

[NUBASE2020-1] 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.

[AME2020_II-3] Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.

[9] 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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