Isotopes of curium

Actinides				Half-life	Fission products
²⁴⁴Cm	²⁴¹Pu ^f	²⁵⁰Cf	²⁴³Cm^f	10–30 y	¹³⁷Cs	⁹⁰Sr	⁸⁵Kr
²³²U ^f		²³⁸Pu	f is for fissile	69–90 y			¹⁵¹Sm nc➔
4n	²⁴⁹Cf ^f	²⁴²Am^f	f is for fissile	141–351	No fission product has half-life 10² to 2×10⁵ years
4n	²⁴¹Am		²⁵¹Cf ^f	431–898
²⁴⁰Pu	²²⁹Th	²⁴⁶Cm	²⁴³Am	5–7 ky
4n	²⁴⁵Cm^f	²⁵⁰Cm	²³⁹Pu ^f	8–24 ky
	²³³U ^f	²³⁰Th	²³¹Pa	32–160
	4n+1	²³⁴U	4n+3	211–290	⁹⁹Tc		¹²⁶Sn	⁷⁹Se
²⁴⁸Cm	4n+1	²⁴²Pu		340–373	Long-lived fission products
	²³⁷Np	4n+2		1–2 My	⁹³Zr	¹³⁵Cs nc➔
²³⁶U	4n+1		²⁴⁷Cm^f	6–23 My		¹⁰⁷Pd	¹²⁹I
²⁴⁴Pu				80 My	>7%	>5%	>1%	>.1%
²³²Th		²³⁸U	²³⁵U ^f	0.7–12 Gy	fission product yield

Curium (Cm) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope synthesized was ²⁴²Cm in 1944.

There are 21 known radioisotopes with atomic masses ranging from ²³²Cm to ²⁵²Cm. There are also four known nuclear isomers (^243mCm, ^244mCm, ^245mCm, and ^249mCm). The longest-lived isotope is ²⁴⁷Cm, with a half-life of 15.6 million years. The longest-lived isomer is ^244mCm with a half-life of 34 milliseconds.

Table

nuclide symbol	Z (p)	N (n)	isotopic mass (u)	half-life	decay mode(s)^[1]^{[n 1]}	daughter isotopes^{[n 2]}	spin
nuclide symbol	excitation energy			half-life	decay mode(s)^[1]^{[n 1]}	daughter isotopes^{[n 2]}	spin
²³²Cm	96	136		1? min			0+
²³³Cm	96	137	233.05077(8)	1# min	β⁺	²³³Am	3/2+#
²³³Cm	96	137	233.05077(8)	1# min	α	²²⁹Pu	3/2+#
²³⁴Cm	96	138	234.05016(2)	51(12) s	β⁺	²³⁴Am	0+
²³⁴Cm	96	138	234.05016(2)	51(12) s	α	²³⁰Pu	0+
²³⁵Cm	96	139	235.05143(22)#	5# min	β⁺	²³⁵Am	5/2+#
²³⁵Cm	96	139	235.05143(22)#	5# min	α	²³¹Pu	5/2+#
²³⁶Cm	96	140	236.05141(22)#	10# min	β⁺	²³⁶Am	0+
²³⁶Cm	96	140	236.05141(22)#	10# min	α	²³²Pu	0+
²³⁷Cm	96	141	237.05290(22)#	20# min	β⁺	²³⁷Am	5/2+#
²³⁷Cm	96	141	237.05290(22)#	20# min	α	²³³Pu	5/2+#
²³⁸Cm	96	142	238.05303(4)	2.4(1) h	EC (90%)	²³⁸Am	0+
²³⁸Cm	96	142	238.05303(4)	2.4(1) h	α (10%)	²³⁴Pu	0+
²³⁹Cm	96	143	239.05496(11)#	~2.9 h	β⁺ (99.9%)	²³⁹Am	(7/2-)
²³⁹Cm	96	143	239.05496(11)#	~2.9 h	α (.1%)	²³⁵Pu	(7/2-)
²⁴⁰Cm	96	144	240.0555295(25)	27(1) d	α (99.5%)	²³⁶Pu	0+
					EC (.5%)	²⁴⁰Am
					SF (3.9×10⁻⁶%)	(various)
²⁴¹Cm	96	145	241.0576530(23)	32.8(2) d	EC (99%)	²⁴¹Am	1/2+
²⁴¹Cm	96	145	241.0576530(23)	32.8(2) d	α (1%)	²³⁷Pu	1/2+
²⁴²Cm^{[n 3]}	96	146	242.0588358(20)	162.8(2) d	α	²³⁸Pu	0+
					SF (6.33×10⁻⁶%)	(various)
					CD (10⁻¹⁴%)^{[n 4]}	²⁰⁸Pb ³⁴Si
					β⁺β⁺ (rare)	²⁴²Pu
²⁴³Cm	96	147	243.0613891(22)	29.1(1) a	α (99.71%)	²³⁹Pu	5/2+
					EC (.29%)	²⁴³Am
					SF (5.3×10⁻⁹%)	(various)
^243mCm	87.4(1) keV			1.08(3) µs			1/2+
²⁴⁴Cm^{[n 3]}	96	148	244.0627526(20)	18.10(2) a	α	²⁴⁰Pu	0+
²⁴⁴Cm^{[n 3]}	96	148	244.0627526(20)	18.10(2) a	SF (1.34×10⁻⁴%)	(various)	0+
^244mCm	1040.188(12) keV			34(2) ms	IT	²⁴⁴Cm	6+
²⁴⁵Cm	96	149	245.0654912(22)	8.5(1)×10³ a	α	²⁴¹Pu	7/2+
²⁴⁵Cm	96	149	245.0654912(22)	8.5(1)×10³ a	SF (6.1×10⁻⁷%)	(various)	7/2+
^245mCm	355.90(10) keV			290(20) ns			1/2+
²⁴⁶Cm	96	150	246.0672237(22)	4.76(4)×10³ a	α (99.97%)	²⁴²Pu	0+
²⁴⁶Cm	96	150	246.0672237(22)	4.76(4)×10³ a	SF (.0261%)	(various)	0+
²⁴⁷Cm	96	151	247.070354(5)	1.56(5)×10⁷ a	α	²⁴³Pu	9/2-
²⁴⁸Cm	96	152	248.072349(5)	3.48(6)×10⁵ a	α (91.74%)	²⁴⁴Pu	0+
					SF (8.26%)	(various)
					β^-β^- (rare)	²⁴⁸Cf
²⁴⁹Cm	96	153	249.075953(5)	64.15(3) min	β^-	²⁴⁹Bk	1/2(+)
^249mCm	48.758(17) keV			23 µs			(7/2+)
²⁵⁰Cm	96	154	250.078357(12)	8,300# a	SF (80%)^{[n 5]}	(various)	0+
					α (11%)	²⁴⁶Pu
					β^- (9%)	²⁵⁰Bk
²⁵¹Cm	96	155	251.082285(24)	16.8(2) min	β^-	²⁵¹Bk	(1/2+)
²⁵²Cm	96	156	252.08487(32)#	<1 d	β^-	²⁵²Bk	0+

^ Abbreviations:
CD: Cluster decay
EC: Electron capture
IT: Isomeric transition
SF: Spontaneous fission
^ Bold for stable isotopes
^ ^a ^b Most common isotopes
^ Heaviest known nuclide to undergo cluster decay
^ Lightest nuclide to undergo spontaneous fission as the main decay mode

Notes

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 americium	Isotopes of curium	Isotopes of berkelium
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