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Standard atomic weightAr°(Cd) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Naturally occurringcadmium (48Cd) is composed of 8isotopes. For two of them, naturalradioactivity was observed, and three others are predicted to be radioactive but their decays have not been observed, due to extremely longhalf-lives. The two natural radioactive isotopes are113Cd (beta decay, half-life is 8.04 × 1015 years) and116Cd (two-neutrinodouble beta decay, half-life is 2.8 × 1019 years). The other three are106Cd,108Cd (double electron capture), and114Cd (double beta decay); only lower limits on their half-life times have been set. Three isotopes—110Cd,111Cd, and112Cd—are theoretically stable. Among the isotopes absent in natural cadmium, the most long-lived are109Cd with a half-life of 462.6 days, and115Cd 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 12 knownmeta states, with the most stable being113mCd (t1/2 14.1 years),115mCd (t1/2 44.6 days) and117mCd (t1/2 3.36 hours).
The known isotopes of cadmium range inatomic mass from 94.950 u (95Cd) to 131.946 u (132Cd). The primarydecay mode before the second most abundant stable isotope,112Cd, iselectron capture and the primary modes after arebeta emission and electron capture. The primarydecay product before112Cd is element 47 (silver) and the primary product after is element 49 (indium).
A 2021 study has shown at high ionic strengths, Cd isotope fractionation mainly depends on its complexation with carboxylic sites. At low ionic strengths, nonspecific Cd binding induced by electrostatic attractions plays a dominant role and promotes Cd isotope fractionation during complexation.[4]
Nuclide [n 1] | Z | N | Isotopic mass(Da)[5] [n 2][n 3] | Half-life[1] [n 4] | Decay mode[1] [n 5] | Daughter isotope [n 6][n 7] | Spin and parity[1] [n 8][n 9] | Natural abundance(mole fraction) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Excitation energy[n 9] | Normal proportion[1] | Range of variation | |||||||||||||||||
94Cd | 48 | 46 | 93.95659(54)# | 80# ms [>760 ns] | 0+ | ||||||||||||||
95Cd | 48 | 47 | 94.94948(61)# | 32(3) ms | β+ (95.4%) | 95Ag | 9/2+# | ||||||||||||
β+,p (4.6%) | 94Pd | ||||||||||||||||||
96Cd | 48 | 48 | 95.94034(44)# | 1.003(47) s | β+ (98.4%) | 96Ag | 0+ | ||||||||||||
β+, p (1.6%) | 95Pd | ||||||||||||||||||
96m1Cd | 6000(1400) keV | 511(26) ms | β+ (84.6%) | 96Ag | 16+ | ||||||||||||||
β+, p (15.4%) | 95Pd | ||||||||||||||||||
96m2Cd | 5605(5) keV | 198(18) ns | IT | 96Cd | (12−,13−) | ||||||||||||||
97Cd | 48 | 49 | 96.93480(45) | 1.16(5) s | β+ (92.6%) | 97Ag | (9/2+) | ||||||||||||
β+, p (7.4%) | 96Pd | ||||||||||||||||||
97m1Cd | 1245.1(2) keV | 730(70) μs | IT | 97Cd | (1/2−) | ||||||||||||||
97m2Cd | 2620(580) keV | 3.86(6) s | β+ (74.9%) | 97Ag | (25/2+) | ||||||||||||||
β+, p (25.1%) | 96Pd | ||||||||||||||||||
98Cd | 48 | 50 | 97.927389(56) | 9.29(10) s | β+ (>99.97%) | 98Ag | 0+ | ||||||||||||
β+, p (<0.029%) | 97Pd | ||||||||||||||||||
98m1Cd | 2428.3(4) keV | 154(16) ns | IT | 98Cd | (8+) | ||||||||||||||
98m2Cd | 6635(2) keV | 224(5) ns | IT | 98Cd | (12+) | ||||||||||||||
99Cd | 48 | 51 | 98.9249258(17) | 17(1) s | β+ (99.79%) | 99Ag | 5/2+# | ||||||||||||
β+, p (0.21%) | 98Pd | ||||||||||||||||||
β+, α (<10−4%) | 95Rh | ||||||||||||||||||
100Cd | 48 | 52 | 99.9203488(18) | 49.1(5) s | β+ | 100Ag | 0+ | ||||||||||||
101Cd | 48 | 53 | 100.9185862(16) | 1.36(5) min | β+ | 101Ag | 5/2+ | ||||||||||||
102Cd | 48 | 54 | 101.9144818(18) | 5.5(5) min | β+ | 102Ag | 0+ | ||||||||||||
103Cd | 48 | 55 | 102.9134169(19) | 7.3(1) min | β+ | 103Ag | 5/2+ | ||||||||||||
104Cd | 48 | 56 | 103.9098562(18) | 57.7(10) min | β+ | 104Ag | 0+ | ||||||||||||
105Cd | 48 | 57 | 104.9094639(15) | 55.5(4) min | β+ | 105Ag | 5/2+ | ||||||||||||
105mCd | 2517.6(5) keV | 4.5(5) μs | IT | 105Cd | (21/2+) | ||||||||||||||
106Cd | 48 | 58 | 105.9064598(12) | Observationally Stable[n 10] | 0+ | 0.01245(22) | |||||||||||||
107Cd | 48 | 59 | 106.9066120(18) | 6.50(2) h | β+ | 107Ag | 5/2+ | ||||||||||||
108Cd | 48 | 60 | 107.9041836(12) | Observationally Stable[n 11] | 0+ | 0.00888(11) | |||||||||||||
109Cd | 48 | 61 | 108.9049867(16) | 461.3(5) d | EC | 109Ag | 5/2+ | ||||||||||||
109m1Cd | 59.60(7) keV | 11.8(16) μs | IT | 109Cd | 1/2+ | ||||||||||||||
109m2Cd | 463.10(11) keV | 10.6(4) μs | IT | 109Cd | 11/2− | ||||||||||||||
110Cd | 48 | 62 | 109.90300747(41) | Stable | 0+ | 0.12470(61) | |||||||||||||
111Cd[n 12] | 48 | 63 | 110.90418378(38) | Stable | 1/2+ | 0.12795(12) | |||||||||||||
111mCd | 396.214(21) keV | 48.50(9) min | IT | 111Cd | 11/2− | ||||||||||||||
112Cd[n 12] | 48 | 64 | 111.90276390(27) | Stable | 0+ | 0.24109(7) | |||||||||||||
113Cd[n 12][n 13] | 48 | 65 | 112.90440811(26) | 8.04(5)×1015 y | β− | 113In | 1/2+ | 0.12227(7) | |||||||||||
113mCd[n 12] | 263.54(3) keV | 13.89(11) y | β− (99.90%) | 113In | 11/2− | ||||||||||||||
IT (0.0964%) | 113Cd | ||||||||||||||||||
114Cd[n 12] | 48 | 66 | 113.90336500(30) | Observationally Stable[n 14] | 0+ | 0.28754(81) | |||||||||||||
115Cd[n 12] | 48 | 67 | 114.90543743(70) | 53.46(5) h | β− | 115mIn | 1/2+ | ||||||||||||
115mCd | 181.0(5) keV | 44.56(24) d | β− | 115mIn | 11/2− | ||||||||||||||
116Cd[n 12][n 13] | 48 | 68 | 115.90476323(17) | 2.69(9)×1019 y | β−β− | 116Sn | 0+ | 0.07512(54) | |||||||||||
117Cd | 48 | 69 | 116.9072260(11) | 2.503(5) h | β− | 117In | 1/2+ | ||||||||||||
117mCd | 136.4(2) keV | 3.441(9) h | β− | 117In | 11/2− | ||||||||||||||
118Cd | 48 | 70 | 117.906922(21) | 50.3(2) min | β− | 118In | 0+ | ||||||||||||
119Cd | 48 | 71 | 118.909847(40) | 2.69(2) min | β− | 119In | 1/2+ | ||||||||||||
119mCd | 146.54(11) keV | 2.20(2) min | β− | 119In | 11/2− | ||||||||||||||
120Cd | 48 | 72 | 119.9098681(40) | 50.80(21) s | β− | 120In | 0+ | ||||||||||||
121Cd | 48 | 73 | 120.9129637(21) | 13.5(3) s | β− | 121In | 3/2+ | ||||||||||||
121mCd | 214.86(15) keV | 8.3(8) s | β− | 121In | 11/2− | ||||||||||||||
122Cd | 48 | 74 | 121.9134591(25) | 5.98(10) s[6] | β− | 122In | 0+ | ||||||||||||
123Cd | 48 | 75 | 122.9168925(29) | 2.10(2) s | β− | 123In | 3/2+ | ||||||||||||
123mCd | 143(4) keV | 1.82(3) s | β− (?%) | 123In | 11/2− | ||||||||||||||
IT (?%) | 123Cd | ||||||||||||||||||
124Cd | 48 | 76 | 123.9176598(28) | 1.25(2) s | β− | 124In | 0+ | ||||||||||||
125Cd | 48 | 77 | 124.9212576(31) | 680(40) ms | β− | 125In | 3/2+ | ||||||||||||
125m1Cd | 186(4) keV | 480(30) ms | β− | 125In | 11/2− | ||||||||||||||
125m2Cd | 1648(4) keV | 19(3) μs | IT | 125Cd | (19/2+) | ||||||||||||||
126Cd | 48 | 78 | 125.9224303(25) | 512(5) ms | β− | 126In | 0+ | ||||||||||||
127Cd | 48 | 79 | 126.9262033(67) | 480(100) ms | β− | 127In | 3/2+ | ||||||||||||
127m1Cd | 285(8) keV | 360(40) ms | β− | 127In | 11/2− | ||||||||||||||
127m2Cd | 1845(8) keV | 17.5(3) μs | IT | 127Cd | (19/2+) | ||||||||||||||
128Cd | 48 | 80 | 127.9278168(69) | 246(2) ms | β− | 128In | 0+ | ||||||||||||
128m1Cd | 1870.5(3) keV | 270(7) ns | IT | 128Cd | (5−) | ||||||||||||||
128m2Cd | 2714.6(4) keV | 3.56(6) μs | IT | 128Cd | (10+) | ||||||||||||||
128m2Cd | 4286.6(15) keV | 6.3(8) ms | IT | 128Cd | (15−) | ||||||||||||||
129Cd | 48 | 81 | 128.9322356(57) | 147(3) ms | β− (?%) | 129In | 11/2− | ||||||||||||
β−,n (?%) | 128In | ||||||||||||||||||
129m1Cd | 343(8) keV | 157(8) ms | β− (?%) | 129In | 3/2+ | ||||||||||||||
β−,n (?%) | 128In | ||||||||||||||||||
129m2Cd | 2283(8) keV | 3.6(2) ms | IT | 129Cd | (21/2+) | ||||||||||||||
130Cd | 48 | 82 | 129.934388(24) | 126.8(18) ms | β− (96.5%) | 130In | 0+ | ||||||||||||
β−, n (3.5%) | 129In | ||||||||||||||||||
130mCd | 2129.6(10) keV | 240(16) ns | IT | 130Cd | (8+) | ||||||||||||||
131Cd | 48 | 83 | 130.940728(21) | 98(2) ms | β− (96.5%) | 131In | 7/2−# | ||||||||||||
β−, n (3.5%) | 130In | ||||||||||||||||||
132Cd | 48 | 84 | 131.945823(64) | 84(5) ms | β−, n (60%) | 131In | 0+ | ||||||||||||
β− (40%) | 132In | ||||||||||||||||||
133Cd | 48 | 85 | 132.95261(22)# | 61(6) ms | β− (?%) | 133In | 7/2−# | ||||||||||||
β−, n (?%) | 132In | ||||||||||||||||||
134Cd | 48 | 86 | 133.95764(32)# | 65(15) ms | β− | 134In | 0+ | ||||||||||||
This table header & footer: |
EC: | Electron capture |
IT: | Isomeric transition |
n: | Neutron emission |
p: | Proton emission |
t½ (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 | 94.6 | 0.5314 | 77 | β |
Cadmium-113m is a cadmiumradioisotope andnuclear isomer with a half-life of 14.1 years. In a normalthermal reactor, it has a very lowfission product yield, plus its largeneutron capturecross section means that most of even the small amount produced is destroyed in the course of thenuclear fuel's burnup; thus, this isotope is not a significant contributor tonuclear waste.
Fast fission or fission of some heavieractinides[which?] will produce113mCd at higher yields.