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) and the only one theoretically stable; ¹³⁶Ce, ¹³⁸Ce, and ¹⁴²Ce are predicted to undergo double beta decay but this process has never been observed. There are 35 radioisotopes that 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).

Relative atomic mass: 140.116(1).

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)
	excitation energy
^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+
					β^+, p	^121Ba
^123Ce	58	65	122.93540(32)#	3.8(2) s	β^+	^123La	(5/2)(+#)
					β^+, p	^122Ba
^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−)
					β^+, p	^124Ba
^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) d	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) d	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) d	β^+	^137La	3/2+
^137mCe	254.29(5) keV			34.4(3) d	IT (99.22%)	^137Ce	11/2−
					β^+ (.779%)	^137La
^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)	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) d	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+#

1. Abbreviations:
   EC: Electron capture
   IT: Isomeric transition
2. Bold for stable isotopes
3. Theorized to undergo β⁺β⁺ decay to ¹³⁶Ba with a half-life over 38×10¹⁵ years
4. Theorized to undergo β⁺β⁺ decay to ¹³⁸Ba with a half-life over 150×10¹² years
5. Fission product
6. Theoretically capable of spontaneous fission
7. 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

1. "Universal Nuclide Chart". nucleonica. (registration required (help)).

• Isotope masses from:
  • G. Audi; A. H. Wapstra; C. Thibault; J. Blachot; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). 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:
  • J. R. de Laeter; J. K. Böhlke; P. De Bièvre; H. Hidaka; H. S. Peiser; K. J. R. Rosman; 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.
  • 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. 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; O. Bersillon (2003). "The NUBASE evaluation of nuclear and decay properties" (PDF). Nuclear Physics A 729: 3–128. Bibcode:2003NuPhA.729....3A. doi:10.1016/j.nuclphysa.2003.11.001.
  • National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. 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 978-0-8493-0485-9.