Isotopes of cerium

Naturally occurring cerium (Ce) is composed of 4 stable isotopes: ¹³⁶Ce, ¹³⁸Ce, ¹⁴⁰Ce, and ¹⁴²Ce with ¹⁴⁰Ce being the most abundant (88.48% natural abundance); ¹³⁶Ce, ¹³⁸Ce, and ¹⁴²Ce are predicted to undergo double beta decay but this process has never been observed. 35 radioisotopes have been characterized with the most stable being ¹⁴⁴Ce with a half-life of 284.893 days, ¹³⁹Ce with a half-life of 137.640 days, and ¹⁴¹Ce with a half-life of 32.501 days. All of the remaining radioactive isotopes have half-lives that are less than 4 days and the majority of these have half-lives that are less than 10 minutes. This element also has 10 meta states.

The isotopes of cerium range in atomic weight from 119 u (¹¹⁹Ce) to 157 u (¹⁵⁷Ce).

Standard atomic mass: 140.116(1) u

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)^[1]^{[n 1]}	daughter isotope(s)^{[n 2]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	excitation energy			half-life	decay mode(s)^[1]^{[n 1]}	daughter isotope(s)^{[n 2]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
¹¹⁹Ce	58	61	118.95276(64)#	200# ms	β⁺	¹¹⁹La	5/2+#
¹²⁰Ce	58	62	119.94664(75)#	250# ms	β⁺	¹²⁰La	0+
¹²¹Ce	58	63	120.94342(54)#	1.1(1) s	β⁺	¹²¹La	(5/2)(+#)
¹²²Ce	58	64	121.93791(43)#	2# s	β⁺	¹²²La	0+
¹²²Ce	58	64	121.93791(43)#	2# s	β⁺, p	¹²¹Ba	0+
¹²³Ce	58	65	122.93540(32)#	3.8(2) s	β⁺	¹²³La	(5/2)(+#)
¹²³Ce	58	65	122.93540(32)#	3.8(2) s	β⁺, p	¹²²Ba	(5/2)(+#)
¹²⁴Ce	58	66	123.93041(32)#	9.1(12) s	β⁺	¹²⁴La	0+
¹²⁵Ce	58	67	124.92844(21)#	9.3(3) s	β⁺	¹²⁵La	(7/2-)
¹²⁵Ce	58	67	124.92844(21)#	9.3(3) s	β⁺, p	¹²⁴Ba	(7/2-)
¹²⁶Ce	58	68	125.92397(3)	51.0(3) s	β⁺	¹²⁶La	0+
¹²⁷Ce	58	69	126.92273(6)	29(2) s	β⁺	¹²⁷La	5/2+#
¹²⁸Ce	58	70	127.91891(3)	3.93(2) min	β⁺	¹²⁸La	0+
¹²⁹Ce	58	71	128.91810(3)	3.5(3) min	β⁺	¹²⁹La	(5/2+)
¹³⁰Ce	58	72	129.91474(3)	22.9(5) min	β⁺	¹³⁰La	0+
^130mCe	2453.6(3) keV			100(8) ns			(7-)
¹³¹Ce	58	73	130.91442(4)	10.2(3) min	β⁺	¹³¹La	(7/2+)
^131mCe	61.8(1) keV			5.0(10) min	β⁺	¹³¹La	(1/2+)
¹³²Ce	58	74	131.911460(22)	3.51(11) h	β⁺	¹³²La	0+
^132mCe	2340.8(5) keV			9.4(3) ms	IT	¹³²Ce	(8-)
¹³³Ce	58	75	132.911515(18)	97(4) min	β⁺	¹³³La	1/2+
^133mCe	37.1(8) keV			4.9(4) h	β⁺	¹³³La	9/2-
¹³⁴Ce	58	76	133.908925(22)	3.16(4) d	EC	¹³⁴La	0+
¹³⁵Ce	58	77	134.909151(12)	17.7(3) h	β⁺	¹³⁵La	1/2(+)
^135mCe	445.8(2) keV			20(1) s	IT	¹³⁵Ce	(11/2-)
¹³⁶Ce	58	78	135.907172(14)	Observationally Stable^{[n 3]}			0+	0.00185(2)	0.00185-0.00186
^136mCe	3095.5(4) keV			2.2(2) µs			10+
¹³⁷Ce	58	79	136.907806(14)	9.0(3) h	β⁺	¹³⁷La	3/2+
^137mCe	254.29(5) keV			34.4(3) h	IT (99.22%)	¹³⁷Ce	11/2-
^137mCe	254.29(5) keV			34.4(3) h	β⁺ (.779%)	¹³⁷La	11/2-
¹³⁸Ce	58	80	137.905991(11)	Observationally Stable^{[n 4]}			0+	0.00251(2)	0.00251-0.00254
^138mCe	2129.17(12) keV			8.65(20) ms	IT	¹³⁸Ce	7-
¹³⁹Ce	58	81	138.906653(8)	137.641(20) d	EC	¹³⁹La	3/2+
^139mCe	754.24(8) keV			56.54(13) s	IT	¹³⁹Ce	11/2-
¹⁴⁰Ce^{[n 5]}	58	82	139.9054387(26)	Observationally Stable^{[n 6]}			0+	0.88450(51)	0.88446-0.88449
^140mCe	2107.85(3) keV			7.3(15) µs			6+
¹⁴¹Ce^{[n 5]}	58	83	140.9082763(26)	32.508(13) d	β^-	¹⁴¹Pr	7/2-
¹⁴²Ce^{[n 5]}	58	84	141.909244(3)	Observationally Stable^{[n 7]}			0+	0.11114(51)	0.11114-0.11114
¹⁴³Ce^{[n 5]}	58	85	142.912386(3)	33.039(6) h	β^-	¹⁴³Pr	3/2-
¹⁴⁴Ce^{[n 5]}	58	86	143.913647(4)	284.91(5) d	β^-	^144mPr	0+
¹⁴⁵Ce	58	87	144.91723(4)	3.01(6) min	β^-	¹⁴⁵Pr	(3/2-)
¹⁴⁶Ce	58	88	145.91876(7)	13.52(13) min	β^-	¹⁴⁶Pr	0+
¹⁴⁷Ce	58	89	146.92267(3)	56.4(10) s	β^-	¹⁴⁷Pr	(5/2-)
¹⁴⁸Ce	58	90	147.92443(3)	56(1) s	β^-	¹⁴⁸Pr	0+
¹⁴⁹Ce	58	91	148.9284(1)	5.3(2) s	β^-	¹⁴⁹Pr	(3/2-)#
¹⁵⁰Ce	58	92	149.93041(5)	4.0(6) s	β^-	¹⁵⁰Pr	0+
¹⁵¹Ce	58	93	150.93398(11)	1.02(6) s	β^-	¹⁵¹Pr	3/2-#
¹⁵²Ce	58	94	151.93654(21)#	1.4(2) s	β^-	¹⁵²Pr	0+
¹⁵³Ce	58	95	152.94058(43)#	500# ms [>300 ns]	β^-	¹⁵³Pr	3/2-#
¹⁵⁴Ce	58	96	153.94342(54)#	300# ms [>300 ns]	β^-	¹⁵⁴Pr	0+
¹⁵⁵Ce	58	97	154.94804(64)#	200# ms [>300 ns]	β^-	¹⁵⁵Pr	5/2-#
¹⁵⁶Ce	58	98	155.95126(64)#	150# ms	β^-	¹⁵⁶Pr	0+
¹⁵⁷Ce	58	99	156.95634(75)#	50# ms	β^-	¹⁵⁷Pr	7/2+#

^ Abbreviations:
EC: Electron capture
IT: Isomeric transition
^ Bold for stable isotopes
^ Theorized to undergo β⁺β⁺ decay to ¹³⁶Ba with a half-life over 38×10¹⁵ years
^ Theorized to undergo β⁺β⁺ decay to ¹³⁸Ba with a half-life over 150×10¹² years
^ ^a ^b ^c ^d ^e Fission product
^ Theoretically capable of spontaneous fission
^ Theorized to undergo β^-β^- decay to ¹⁴²Nd with a half-life over 50×10¹⁵ years

Notes

Evaluated isotopic composition is for most but not all commercial samples.
Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.
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

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

Isotope masses from:
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (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. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
Isotopic compositions and standard atomic masses from:
- J. R. de Laeter, J. K. Böhlke, P. De Bièvre, H. Hidaka, H. S. Peiser, K. J. R. Rosman and P. D. P. Taylor (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry 75 (6): 683–800. doi:10.1351/pac200375060683. http://www.iupac.org/publications/pac/75/6/0683/pdf/.
- M. E. Wieser (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051. http://iupac.org/publications/pac/78/11/2051/pdf/. Lay summary.
Half-life, spin, and isomer data selected from the following sources. See editing notes on this article's talk page.
- G. Audi, A. H. Wapstra, C. Thibault, J. Blachot and O. Bersillon (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. http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf.
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. Retrieved September 2005.
- N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859.

Isotopes of lanthanum	Isotopes of cerium	Isotopes of praseodymium
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