Isotopes of cadmium

Naturally occurring cadmium (Cd) is composed of 8 isotopes. For two of them, natural radioactivity was observed, and three others are predicted to be radioactive but their decays were never observed, due to extremely long half-life times. The two natural radioactive isotopes are ¹¹³Cd (beta decay, half-life is 7.7 × 10¹⁵ years) and ¹¹⁶Cd (two-neutrino double beta decay, half-life is 2.9 × 10¹⁹ years). The other three are ¹⁰⁶Cd, ¹⁰⁸Cd (double electron capture), and ¹¹⁴Cd (double beta decay); only lower limits on their half-life times have been set. At least three isotopes - ¹¹⁰Cd, ¹¹¹Cd, and ¹¹²Cd - are absolutely stable (except, theoretically, to spontaneous fission). Among the isotopes absent in the natural cadmium, the most long-lived are ¹⁰⁹Cd with a half-life of 462.6 days, and ¹¹⁵Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives that are less than 2.5 hours and the majority of these have half-lives that are less than 5 minutes. This element also has 8 known meta states with the most stable being ^113mCd (t_1/2 14.1 years), ^115mCd (t_1/2 44.6 days) and ^117mCd (t_1/2 3.36 hours).

The known isotopes of cadmium range in atomic mass from 94.950 u (⁹⁵Cd) to 131.946 u (¹³²Cd). The primary decay mode before the second most abundant stable isotope, ¹¹²Cd, is electron capture and the primary modes after are beta emission and electron capture. The primary decay product before ¹¹²Cd is element 47 (silver) and the primary product after is element 49 (indium).
Standard atomic mass: 112.411(8) u

Cadmium-113m

Medium-lived
fission products
	t_½ (year)	Yield (%)	Q (keV)	βγ
¹⁵⁵Eu	4.76	0.0803	252	βγ
⁸⁵Kr	10.76	0.2180	687	βγ
^113mCd	14.1	0.0008	316	β
⁹⁰Sr	28.9	4.505	2826	β
¹³⁷Cs	30.23	6.337	1176	βγ
^121mSn	43.9	0.00005	390	βγ
¹⁵¹Sm	88.8	0.5314	77	β

Cadmium-113m is a cadmium radioisotope and nuclear isomer with a halflife of 14.1 years. In a normal thermal reactor, it has a very low fission product yield, plus its large neutron capture cross section means that most of even the small amount produced is destroyed in the course of the nuclear fuel's burnup; thus, this isotope is not a significant contributor to nuclear waste.

Fast fission or fission of some heavier actinides will produce ^113mCd at higher yields.

Table

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life^{[n 1]}	decay mode(s)^[1]^{[n 2]}	daughter isotope(s)^{[n 3]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
nuclide symbol	excitation energy			half-life^{[n 1]}	decay mode(s)^[1]^{[n 2]}	daughter isotope(s)^{[n 3]}	nuclear spin	representative isotopic composition (mole fraction)	range of natural variation (mole fraction)
⁹⁵Cd	48	47	94.94987(64)#	5# ms			9/2 #
⁹⁶Cd	48	48	95.93977(54)#	1# s	β	⁹⁶Ag	0
⁹⁷Cd	48	49	96.93494(43)#	2.8(6) s	β (>99.9%)	⁹⁷Ag	9/2 #
⁹⁷Cd	48	49	96.93494(43)#	2.8(6) s	β, p (<.1%)	⁹⁶Pd	9/2 #
⁹⁸Cd	48	50	97.92740(8)	9.2(3) s	β (99.975%)	⁹⁸Ag	0
⁹⁸Cd	48	50	97.92740(8)	9.2(3) s	β, p (.025%)	⁹⁷Ag	0
^98mCd	2427.5(6) keV			190(20) ns			8 #
⁹⁹Cd	48	51	98.92501(22)#	16(3) s	β (99.78%)	⁹⁹Ag	(5/2 )
					β, p (.21%)	⁹⁸Pd
					β, α (10⁻⁴%)	⁹⁴Rh
¹⁰⁰Cd	48	52	99.92029(10)	49.1(5) s	β	¹⁰⁰Ag	0
¹⁰¹Cd	48	53	100.91868(16)	1.36(5) min	β	¹⁰¹Ag	(5/2 )
¹⁰²Cd	48	54	101.91446(3)	5.5(5) min	β	¹⁰²Ag	0
¹⁰³Cd	48	55	102.913419(17)	7.3(1) min	β	¹⁰³Ag	5/2
¹⁰⁴Cd	48	56	103.909849(10)	57.7(10) min	β	¹⁰⁴Ag	0
¹⁰⁵Cd	48	57	104.909468(12)	55.5(4) min	β	¹⁰⁵Ag	5/2
¹⁰⁶Cd	48	58	105.906459(6)	Observationally Stable^{[n 4]}			0	0.0125(6)
¹⁰⁷Cd	48	59	106.906618(6)	6.50(2) h	β	^107mAg	5/2
¹⁰⁸Cd	48	60	107.904184(6)	Observationally Stable^{[n 5]}			0	0.0089(3)
¹⁰⁹Cd	48	61	108.904982(4)	461.4(12) d	EC	¹⁰⁹Ag	5/2
^109m1Cd	59.6(4) keV			12(2) µs			1/2
^109m2Cd	463.0(5) keV			10.9(5) µs			11/2-
¹¹⁰Cd	48	62	109.9030021(29)	Stable^{[n 6]}			0	0.1249(18)
¹¹¹Cd^{[n 7]}	48	63	110.9041781(29)	Stable^{[n 6]}			1/2	0.1280(12)
^111mCd	396.214(21) keV			48.50(9) min	IT	¹¹¹Cd	11/2-
¹¹²Cd^{[n 7]}	48	64	111.9027578(29)	Stable^{[n 6]}			0	0.2413(21)
¹¹³Cd^{[n 7]}^{[n 8]}	48	65	112.9044017(29)	7.7(3)×10¹⁵ a	β⁻	¹¹³In	1/2	0.1222(12)
^113mCd^{[n 7]}	263.54(3) keV			14.1(5) a	β⁻ (99.86%)	¹¹³In	11/2-
^113mCd^{[n 7]}	263.54(3) keV			14.1(5) a	IT (.139%)	¹¹³Cd	11/2-
¹¹⁴Cd^{[n 7]}	48	66	113.9033585(29)	Observationally Stable^{[n 9]}			0	0.2873(42)
¹¹⁵Cd^{[n 7]}	48	67	114.9054310(29)	53.46(5) h	β⁻	^115mIn	1/2
^115mCd	181.0(5) keV			44.56(24) d	β⁻	^115mIn	(11/2)-
¹¹⁶Cd^{[n 7]}^{[n 8]}	48	68	115.904756(3)	3.1(4)×10¹⁹ a	β⁻β⁻	¹¹⁶Sn	0	0.0749(18)
¹¹⁷Cd	48	69	116.907219(4)	2.49(4) h	β⁻	^117mIn	1/2
^117mCd	136.4(2) keV			3.36(5) h	β⁻	^117mIn	(11/2)-
¹¹⁸Cd	48	70	117.906915(22)	50.3(2) min	β⁻	¹¹⁸In	0
¹¹⁹Cd	48	71	118.90992(9)	2.69(2) min	β⁻	^119mIn	(3/2 )
^119mCd	146.54(11) keV			2.20(2) min	β⁻	^119mIn	(11/2-)#
¹²⁰Cd	48	72	119.90985(2)	50.80(21) s	β⁻	¹²⁰In	0
¹²¹Cd	48	73	120.91298(9)	13.5(3) s	β⁻	^121mIn	(3/2 )
^121mCd	214.86(15) keV			8.3(8) s	β⁻	^121mIn	(11/2-)
¹²²Cd	48	74	121.91333(5)	5.24(3) s	β⁻	¹²²In	0
¹²³Cd	48	75	122.91700(4)	2.10(2) s	β⁻	^123mIn	(3/2)
^123mCd	316.52(23) keV			1.82(3) s	β⁻	¹²³In	(11/2-)
^123mCd	316.52(23) keV			1.82(3) s	IT	²³Cd	(11/2-)
¹²⁴Cd	48	76	123.91765(7)	1.25(2) s	β⁻	¹²⁴In	0
¹²⁵Cd	48	77	124.92125(7)	0.65(2) s	β⁻	^125mIn	(3/2 )#
^125mCd	50(70) keV			570(90) ms	β⁻	¹²⁵In	11/2-#
¹²⁶Cd	48	78	125.92235(6)	0.515(17) s	β⁻	¹²⁶In	0
¹²⁷Cd	48	79	126.92644(8)	0.37(7) s	β⁻	^127mIn	(3/2 )
¹²⁸Cd	48	80	127.92776(32)	0.28(4) s	β⁻	¹²⁸In	0
¹²⁹Cd	48	81	128.93215(32)#	242(8) ms	β⁻ (>99.9%)	¹²⁹In	3/2 #
¹²⁹Cd	48	81	128.93215(32)#	242(8) ms	IT (<.1%)	¹²⁹Cd	3/2 #
^129mCd	0(200)# keV			104(6) ms			11/2-#
¹³⁰Cd	48	82	129.9339(3)	162(7) ms	β⁻ (96%)	¹³⁰In	0
¹³⁰Cd	48	82	129.9339(3)	162(7) ms	β⁻, n (4%)	¹²⁹In	0
¹³¹Cd	48	83	130.94067(32)#	68(3) ms			7/2-#
¹³²Cd	48	84	131.94555(54)#	97(10) ms			0

^ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
^ Abbreviations:
EC: Electron capture
IT: Isomeric transition
^ Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
^ Believed to decay by ββ to ¹⁰⁶Pd with a half-life over 4.1×10²⁰ years
^ Believed to decay by ββ to ¹⁰⁸Pd with a half-life over 4.1×10¹⁷ years
^ ^a ^b ^c Theoretically capable of spontaneous fission
^ ^a ^b ^c ^d ^e ^f ^g Fission product
^ ^a ^b Primordial radionuclide
^ Believed to undergo β⁻β⁻ decay to ¹¹⁴Sn with a half-life over 6.4×10¹⁸ years

Notes

The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
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.
Hyperdeformation is predicted to be found in ¹⁰⁷Cd.

References

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. Bibcode:2003NuPhA.729....3A. 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. Bibcode:2003NuPhA.729....3A. 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 978-0-8493-0485-9. {{cite book}}: Unknown parameter |nopp= ignored (|no-pp= suggested) (help)

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

[1] Bold for isotopes with half-lives longer than the age of the universe (nearly stable)

[3] Abbreviations:
EC: Electron capture
IT: Isomeric transition

[4] Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)

[5] Believed to decay by ββ to ¹⁰⁶Pd with a half-life over 4.1×10²⁰ years

[6] Believed to decay by ββ to ¹⁰⁸Pd with a half-life over 4.1×10¹⁷ years

[SF-7] Theoretically capable of spontaneous fission

[FP-8] ^ ^a ^b ^c ^d ^e ^f ^g Fission product

[PN-9] Primordial radionuclide

[10] Believed to undergo β⁻β⁻ decay to ¹¹⁴Sn with a half-life over 6.4×10¹⁸ years

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

[n 1]

[1]

[n 2]

[n 3]

[n 4]

[n 5]

[n 6]

[n 7]

[n 8]

[n 9]