Isotopes of cadmium

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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. 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_½ 14.1 years), ^115mCd (t_½ 44.6 days) and ^117mCd (t_½ 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

[edit] 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)
nuclide symbol	excitation energy			half-life	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	0+
⁹⁷Cd	48	49	96.93494(43)#	2.8(6) s	9/2+#
⁹⁸Cd	48	50	97.92740(8)	9.2(3) s	0+
^98mCd	2427.5(6) keV			190(20) ns	8+#
⁹⁹Cd	48	51	98.92501(22)#	16(3) s	(5/2+)
¹⁰⁰Cd	48	52	99.92029(10)	49.1(5) s	0+
¹⁰¹Cd	48	53	100.91868(16)	1.36(5) min	(5/2+)
¹⁰²Cd	48	54	101.91446(3)	5.5(5) min	0+
¹⁰³Cd	48	55	102.913419(17)	7.3(1) min	5/2+
¹⁰⁴Cd	48	56	103.909849(10)	57.7(10) min	0+
¹⁰⁵Cd	48	57	104.909468(12)	55.5(4) min	5/2+
¹⁰⁶Cd	48	58	105.906459(6)	STABLE [>410E+18 a]	0+	0.0125(6)
¹⁰⁷Cd	48	59	106.906618(6)	6.50(2) h	5/2+
¹⁰⁸Cd	48	60	107.904184(6)	STABLE [>410E+15 a]	0+	0.0089(3)
¹⁰⁹Cd	48	61	108.904982(4)	461.4(12) d	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	0+	0.1249(18)
¹¹¹Cd	48	63	110.9041781(29)	STABLE	1/2+	0.1280(12)
^111mCd	396.214(21) keV			48.50(9) min	11/2-
¹¹²Cd	48	64	111.9027578(29)	STABLE	0+	0.2413(21)
¹¹³Cd	48	65	112.9044017(29)	7.7(3)E+15 a	1/2+	0.1222(12)
^113mCd	263.54(3) keV			14.1(5) a	11/2-
¹¹⁴Cd	48	66	113.9033585(29)	STABLE [>6.4E+18 a]	0+	0.2873(42)
¹¹⁵Cd	48	67	114.9054310(29)	53.46(5) h	1/2+
^115mCd	181.0(5) keV			44.56(24) d	(11/2)-
¹¹⁶Cd	48	68	115.904756(3)	3.1(4)E+19 a	0+	0.0749(18)
¹¹⁷Cd	48	69	116.907219(4)	2.49(4) h	1/2+
^117mCd	136.4(2) keV			3.36(5) h	(11/2)-
¹¹⁸Cd	48	70	117.906915(22)	50.3(2) min	0+
¹¹⁹Cd	48	71	118.90992(9)	2.69(2) min	(3/2+)
^119mCd	146.54(11) keV			2.20(2) min	(11/2-)#
¹²⁰Cd	48	72	119.90985(2)	50.80(21) s	0+
¹²¹Cd	48	73	120.91298(9)	13.5(3) s	(3/2+)
^121mCd	214.86(15) keV			8.3(8) s	(11/2-)
¹²²Cd	48	74	121.91333(5)	5.24(3) s	0+
¹²³Cd	48	75	122.91700(4)	2.10(2) s	(3/2)+
^123mCd	316.52(23) keV			1.82(3) s	(11/2-)
¹²⁴Cd	48	76	123.91765(7)	1.25(2) s	0+
¹²⁵Cd	48	77	124.92125(7)	0.65(2) s	(3/2+)#
^125mCd	50(70) keV			570(90) ms	11/2-#
¹²⁶Cd	48	78	125.92235(6)	0.515(17) s	0+
¹²⁷Cd	48	79	126.92644(8)	0.37(7) s	(3/2+)
¹²⁸Cd	48	80	127.92776(32)	0.28(4) s	0+
¹²⁹Cd	48	81	128.93215(32)#	242(8) ms	3/2+#
^129mCd	0(200)# keV			104(6) ms	11/2-#
¹³⁰Cd	48	82	129.9339(3)	162(7) ms	0+
¹³¹Cd	48	83	130.94067(32)#	68(3) ms	7/2-#
¹³²Cd	48	84	131.94555(54)#	97(10) ms	0+

[edit] 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.

[edit] 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.