Isotopes of curium: Difference between revisions

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Curium (Cm) has no stable isotopes. A standard atomic mass cannot be given. The isotope with the longest half-life is ²⁴⁷Cm, with a half-life of 15.6 million years.

Table

Actinides and fission products by half-life v t e
Actinides^[1] by decay chain				Half-life range (a)	Fission products of ²³⁵U by yield^[2]
4n	4n + 1	4n + 2	4n + 3	Half-life range (a)	4.5–7%	0.04–1.25%	<0.001%
²²⁸Ra^№				4–6 a		¹⁵⁵Eu^þ
²⁴⁸Bk^[3]				> 9 a
²⁴⁴Cm^ƒ	²⁴¹Pu^ƒ	²⁵⁰Cf	²²⁷Ac^№	10–29 a	⁹⁰Sr	⁸⁵Kr	^113mCd^þ
²³²U^ƒ		²³⁸Pu^ƒ	²⁴³Cm^ƒ	29–97 a	¹³⁷Cs	¹⁵¹Sm^þ	^121mSn
	²⁴⁹Cf^ƒ	^242mAm^ƒ		141–351 a	No fission products have a half-life in the range of 100 a–210 ka ...
	²⁴¹Am^ƒ		²⁵¹Cf^ƒ^[4]	430–900 a
		²²⁶Ra^№	²⁴⁷Bk	1.3–1.6 ka
²⁴⁰Pu	²²⁹Th	²⁴⁶Cm^ƒ	²⁴³Am^ƒ	4.7–7.4 ka
	²⁴⁵Cm^ƒ	²⁵⁰Cm		8.3–8.5 ka
			²³⁹Pu^ƒ	24.1 ka
		²³⁰Th^№	²³¹Pa^№	32–76 ka
²³⁶Np^ƒ	²³³U^ƒ	²³⁴U^№		150–250 ka	⁹⁹Tc^₡	¹²⁶Sn
²⁴⁸Cm		²⁴²Pu		327–375 ka		⁷⁹Se^₡
				1.33 Ma	¹³⁵Cs^₡
	²³⁷Np^ƒ			1.61–6.5 Ma	⁹³Zr	¹⁰⁷Pd
²³⁶U			²⁴⁷Cm^ƒ	15–24 Ma		¹²⁹I^₡
²⁴⁴Pu				80 Ma	... nor beyond 15.7 Ma^[5]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7–14.1 Ga	... nor beyond 15.7 Ma^[5]
₡, has thermal neutron capture cross section in the range of 8–50 barns ƒ, fissile №, primarily a naturally occurring radioactive material (NORM) þ, neutron poison (thermal neutron capture cross section greater than 3k barns)

nuclide symbol	Z (p)	N (n)	isotopic mass (u)	half-life	decay mode(s)^[6]^{[n 1]}	daughter isotopes^{[n 2]}	spin
nuclide symbol	excitation energy			half-life	decay mode(s)^[6]^{[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	²³⁷Cm	96	0+	141	237.05290(22)#	20# min	β⁺	²³⁷Am	5/2+#
α	²³³Pu				²³⁷Cm	96		141	237.05290(22)#	20# min			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 (3.9E-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	96	146	242.0588358(20)	162.8(2) d	α	²³⁸Pu	0+
					SF (6.33E-6%)
					CD (1E-14%)	²⁰⁸Pb, ³⁴Si
					β⁺β⁺ (rare)	²⁴¹Pu
²⁴³Cm	96	147	243.0613891(22)	29.1(1) a	α (99.71%)	²³⁹Pu	5/2+
					EC (.29%)	²⁴³Am
					SF (5.3E-9%)	(various)
^243mCm	87.4(1) keV			1.08(3) µs			1/2+
²⁴⁴Cm	96	148	244.0627526(20)	18.10(2) a	α	²⁴⁰Pu	0+
²⁴⁴Cm	96	148	244.0627526(20)	18.10(2) a	SF (1.34E-4%)	(various)	0+
^244mCm	1040.188(12) keV			34(2) ms	IT	²⁴⁴Cm	6+
²⁴⁵Cm	96	149	245.0654912(22)	8.5(1)E+3 a	α	²⁴¹Pu	7/2+
²⁴⁵Cm	96	149	245.0654912(22)	8.5(1)E+3 a	SF (6.1E-7%)	(various)	7/2+
^245mCm	355.90(10) keV			290(20) ns			1/2+
²⁴⁶Cm	96	150	246.0672237(22)	4.76(4)E+3 a	α (99.97%)	²⁴²Pu	0+
²⁴⁶Cm	96	150	246.0672237(22)	4.76(4)E+3 a	SF (.0261%)	(various)	0+
²⁴⁷Cm	96	151	247.070354(5)	1.56(5)E+7 a	α	²⁴³Pu	9/2-
²⁴⁸Cm	96	152	248.072349(5)	3.48(6)E+5 a	α (91.74%)	²⁴⁴Pu	0+
					SF (8.26%)
					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)	8300# a	SF (80%)^{[n 3]}	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
^ 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

^ Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
^ Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.
^ Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
"The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk²⁴⁸ with a half-life greater than 9 [years]. No growth of Cf²⁴⁸ was detected, and a lower limit for the β⁻ half-life can be set at about 10⁴ [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]."
^ This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
^ Excluding those "classically stable" nuclides with half-lives significantly in excess of ²³²Th; e.g., while ^113mCd has a half-life of only fourteen years, that of ¹¹³Cd is eight quadrillion years.
^ 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" (PDF). Nuclear Physics A. 729: 3–128. doi:10.1016/j.nuclphysa.2003.11.001.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
- 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. {{cite journal}}: Unknown parameter |laysummary= ignored (help)
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" (PDF). Nuclear Physics A. 729: 3–128. doi:10.1016/j.nuclphysa.2003.11.001.{{cite journal}}: CS1 maint: multiple names: authors list (link)
- National Nuclear Data Center. "NuDat 2.1 database". Brookhaven National Laboratory. Retrieved September 2005. {{cite web}}: Check date values in: |accessdate= (help)
- N. E. Holden (2004). "Table of the Isotopes". In D. R. Lide (ed.). CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. Section 11. ISBN 978-0849304859. {{cite book}}: Unknown parameter |nopp= ignored (|no-pp= suggested) (help)

[7] Abbreviations:
CD: Cluster decay
EC: Electron capture
IT: Isomeric transition
SF: Spontaneous fission

[8] Bold for stable isotopes

[9] Lightest nuclide to undergo spontaneous fission as the main decay mode

[1] Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.

[2] Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.

[3] Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
"The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk²⁴⁸ with a half-life greater than 9 [years]. No growth of Cf²⁴⁸ was detected, and a lower limit for the β⁻ half-life can be set at about 10⁴ [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]."

[4] This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".

[5] Excluding those "classically stable" nuclides with half-lives significantly in excess of ²³²Th; e.g., while ^113mCd has a half-life of only fourteen years, that of ¹¹³Cd is eight quadrillion years.

[6] ttp://www.nucleonica.net/unc.aspx

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