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 (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 (t½ 14.1 years), 115mCd (t½ 44.6 days) and 117mCd (t½ 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[edit]

Medium-lived
fission products
Prop:
Unit:
t½
a
Yield
%
Q *
keV
βγ
*
155Eu 4.76 .0803 252 βγ
85Kr 10.76 .2180 687 βγ
113mCd 14.1 .0008 316 β
90Sr 28.9 4.505 2826 β
137Cs 30.23 6.337 1176 βγ
121mSn 43.9 .00005 390 βγ
151Sm 96.6 .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[edit]

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)
excitation energy
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+#
β+, p (<.1%) 96Pd
98Cd 48 50 97.92740(8) 9.2(3) s β+ (99.975%) 98Ag 0+
β+, p (.025%) 97Ag
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-
IT (.139%) 113Cd
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-)
IT 23Cd
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+#
IT (<.1%) 129Cd
129mCd 0(200)# keV 104(6) ms 11/2-#
130Cd 48 82 129.9339(3) 162(7) ms β- (96%) 130In 0+
β-, n (4%) 129In
131Cd 48 83 130.94067(32)# 68(3) ms 7/2-#
132Cd 48 84 131.94555(54)# 97(10) ms 0+
  1. ^ Bold for isotopes with half-lives longer than the age of the universe (nearly stable)
  2. ^ Abbreviations:
    EC: Electron capture
    IT: Isomeric transition
  3. ^ Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe)
  4. ^ Believed to decay by β+β+ to 106Pd with a half-life over 4.1×1020 years
  5. ^ Believed to decay by β+β+ to 108Pd with a half-life over 4.1×1017 years
  6. ^ a b c Theoretically capable of spontaneous fission
  7. ^ a b c d e f g Fission product
  8. ^ a b Primordial radionuclide
  9. ^ Believed to undergo β-β- decay to 114Sn with a half-life over 6.4×1018 years

Notes[edit]

  • 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[edit]

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


Isotopes of silver Isotopes of cadmium Isotopes of indium
Table of nuclides