Isotopes of cerium

Naturally occurring cerium (Ce) is composed of 3 stable isotopes and 1 radioactive isotope; ¹³⁶Ce, ¹³⁸Ce, ¹⁴⁰Ce, and ¹⁴²Ce with ¹⁴⁰Ce being the most abundant (88.48% natural abundance). 27 radioisotopes have been characterized with the most {abundant and/or stable} being ¹⁴²Ce with a half-life of greater than 5×10¹⁶ years, 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 2 meta states.

The isotopes of cerium range in atomic weight from 123 u (¹²³Ce) to 152 u (¹⁵²Ce).

Standard atomic mass: 140.116(1) u

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
	excitation energy
119Ce	58	61	118.95276(64)#	200# ms	5/2+#
120Ce	58	62	119.94664(75)#	250# ms	0+
121Ce	58	63	120.94342(54)#	1.1(1) s	(5/2)(+#)
122Ce	58	64	121.93791(43)#	2# s	0+
123Ce	58	65	122.93540(32)#	3.8(2) s	(5/2)(+#)
124Ce	58	66	123.93041(32)#	9.1(12) s	0+
125Ce	58	67	124.92844(21)#	9.3(3) s	(7/2-)
126Ce	58	68	125.92397(3)	51.0(3) s	0+
127Ce	58	69	126.92273(6)	29(2) s	5/2+#
128Ce	58	70	127.91891(3)	3.93(2) min	0+
129Ce	58	71	128.91810(3)	3.5(3) min	(5/2+)
130Ce	58	72	129.91474(3)	22.9(5) min	0+
130mCe	2453.6(3) keV			100(8) ns	(7-)
131Ce	58	73	130.91442(4)	10.2(3) min	(7/2+)
131mCe	61.8(1) keV			5.0(10) min	(1/2+)
132Ce	58	74	131.911460(22)	3.51(11) h	0+
132mCe	2340.8(5) keV			9.4(3) ms	(8-)
133Ce	58	75	132.911515(18)	97(4) min	1/2+
133mCe	37.1(8) keV			4.9(4) h	9/2-
134Ce	58	76	133.908925(22)	3.16(4) d	0+
135Ce	58	77	134.909151(12)	17.7(3) h	1/2(+)
135mCe	445.8(2) keV			20(1) s	(11/2-)
136Ce	58	78	135.907172(14)	STABLE [>38E+15 a]	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	3/2+
137mCe	254.29(5) keV			34.4(3) h	11/2-
138Ce	58	80	137.905991(11)	STABLE [>150E+12 a]	0+	0.00251(2)	0.00251-0.00254
138mCe	2129.17(12) keV			8.65(20) ms	7-
139Ce	58	81	138.906653(8)	137.641(20) d	3/2+
139mCe	754.24(8) keV			56.54(13) s	11/2-
140Ce	58	82	139.9054387(26)	STABLE	0+	0.88450(51)	0.88446-0.88449
140mCe	2107.85(3) keV			7.3(15) µs	6+
141Ce	58	83	140.9082763(26)	32.508(13) d	7/2-
142Ce	58	84	141.909244(3)	STABLE [>50E+15 a]	0+	0.11114(51)	0.11114-0.11114
143Ce	58	85	142.912386(3)	33.039(6) h	3/2-
144Ce	58	86	143.913647(4)	284.91(5) d	0+
145Ce	58	87	144.91723(4)	3.01(6) min	(3/2-)
146Ce	58	88	145.91876(7)	13.52(13) min	0+
147Ce	58	89	146.92267(3)	56.4(10) s	(5/2-)
148Ce	58	90	147.92443(3)	56(1) s	0+
149Ce	58	91	148.9284(1)	5.3(2) s	(3/2-)#
150Ce	58	92	149.93041(5)	4.0(6) s	0+
151Ce	58	93	150.93398(11)	1.02(6) s	3/2-#
152Ce	58	94	151.93654(21)#	1.4(2) s	0+
153Ce	58	95	152.94058(43)#	500# ms [>300 ns]	3/2-#
154Ce	58	96	153.94342(54)#	300# ms [>300 ns]	0+
155Ce	58	97	154.94804(64)#	200# ms [>300 ns]	5/2-#
156Ce	58	98	155.95126(64)#	150# ms	0+
157Ce	58	99	156.95634(75)#	50# ms	7/2+#

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

• Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
• Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
• Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
  • Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
  • National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
  • David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.