Naturally occurring
cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of ...
(
48Cd) is composed of 8
isotope
Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...
s. For two of them, natural
radioactivity was observed, and three others are predicted to be radioactive but their decays have not been observed, due to extremely long
half-lives
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...
. The two natural radioactive isotopes are
113Cd (
beta decay
In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For ...
, half-life is 8.04 × 10
15 years) and
116Cd (two-neutrino
double beta decay
In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa, inside an atomic nucleus. As in single beta decay, this process allows the atom to move clos ...
, half-life is 2.8 × 10
19 years). The other three are
106Cd,
108Cd (
double electron capture
Double electron capture is a decay mode of an atomic nucleus. For a nuclide (''A'', ''Z'') with a number of nucleons ''A'' and atomic number ''Z'', double electron capture is only possible if the mass of the nuclide (''A'', ''Z''−2) is lower.
...
), 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 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 12 known
meta state
A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy higher energy levels than in the ground state of the same nucleus. "Metastable" describes nuclei whose excited states have ...
s, 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
The atomic mass (''m''a or ''m'') is the mass of an atom. Although the SI unit of mass is the kilogram (symbol: kg), atomic mass is often expressed in the non-SI unit dalton (symbol: Da) – equivalently, unified atomic mass unit (u). 1&nb ...
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
Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Thi ...
and the primary modes after are
beta emission
In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which a beta particle (fast energetic electron or positron) is emitted from an atomic nucleus, transforming the original nuclide to an isobar of that nuclide. For exam ...
and electron capture. The primary
decay product before
112Cd is element 47 (
silver
Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...
) and the primary product after is element 49 (
indium
Indium is a chemical element with the symbol In and atomic number 49. Indium is the softest metal that is not an alkali metal. It is a silvery-white metal that resembles tin in appearance. It is a post-transition metal that makes up 0.21 parts ...
).
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.
List of isotopes
, -
,
95Cd
, style="text-align:right" , 48
, style="text-align:right" , 47
, 94.94987(64)#
, 5# ms
,
,
, 9/2+#
,
,
, -
,
96Cd
, style="text-align:right" , 48
, style="text-align:right" , 48
, 95.93977(54)#
, 1# s
,
β+
,
96Ag
, 0+
,
,
, -
, rowspan=2,
97Cd
, rowspan=2 style="text-align:right" , 48
, rowspan=2 style="text-align:right" , 49
, rowspan=2, 96.93494(43)#
, rowspan=2, 2.8(6) s
, β
+ (>99.9%)
,
97Ag
, rowspan=2, 9/2+#
, rowspan=2,
, rowspan=2,
, -
, β
+,
p (<.1%)
,
96Pd
, -
, rowspan=2,
98Cd
, rowspan=2 style="text-align:right" , 48
, rowspan=2 style="text-align:right" , 50
, rowspan=2, 97.92740(8)
, rowspan=2, 9.2(3) s
, β
+ (99.975%)
,
98Ag
, rowspan=2, 0+
, rowspan=2,
, rowspan=2,
, -
, β
+, p (.025%)
,
97Ag
, -
, style="text-indent:1em" ,
98mCd
, colspan="3" style="text-indent:2em" , 2427.5(6) keV
, 190(20) ns
,
,
, 8+#
,
,
, -
, rowspan=3,
99Cd
, rowspan=3 style="text-align:right" , 48
, rowspan=3 style="text-align:right" , 51
, rowspan=3, 98.92501(22)#
, rowspan=3, 16(3) s
, β
+ (99.78%)
,
99Ag
, rowspan=3, (5/2+)
, rowspan=3,
, rowspan=3,
, -
, β
+, p (.21%)
,
98Pd
, -
, β
+, α (10
−4%)
,
95Rh
, -
,
100Cd
, style="text-align:right" , 48
, style="text-align:right" , 52
, 99.92029(10)
, 49.1(5) s
, β
+
,
100Ag
, 0+
,
,
, -
,
101Cd
, style="text-align:right" , 48
, style="text-align:right" , 53
, 100.91868(16)
, 1.36(5) min
, β
+
,
101Ag
, (5/2+)
,
,
, -
,
102Cd
, style="text-align:right" , 48
, style="text-align:right" , 54
, 101.91446(3)
, 5.5(5) min
, β
+
,
102Ag
, 0+
,
,
, -
,
103Cd
, style="text-align:right" , 48
, style="text-align:right" , 55
, 102.913419(17)
, 7.3(1) min
, β
+
,
103Ag
, 5/2+
,
,
, -
,
104Cd
, style="text-align:right" , 48
, style="text-align:right" , 56
, 103.909849(10)
, 57.7(10) min
, β
+
,
104Ag
, 0+
,
,
, -
,
105Cd
, style="text-align:right" , 48
, style="text-align:right" , 57
, 104.909468(12)
, 55.5(4) min
, β
+
,
105Ag
, 5/2+
,
,
, -
,
106Cd
, style="text-align:right" , 48
, style="text-align:right" , 58
, 105.906459(6)
, colspan=3 align=center,
Observationally Stable
Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes.
Th ...
[Believed to decay by β+β+ to 106Pd with a half-life over 4.1×1020 years]
, 0+
, 0.0125(6)
,
, -
,
107Cd
, style="text-align:right" , 48
, style="text-align:right" , 59
, 106.906618(6)
, 6.50(2) h
, β
+
,
107mAg
, 5/2+
,
,
, -
,
108Cd
, style="text-align:right" , 48
, style="text-align:right" , 60
, 107.904184(6)
, colspan=3 align=center, Observationally Stable
[Believed to decay by β+β+ to 108Pd with a half-life over 4.1×1017 years]
, 0+
, 0.0089(3)
,
, -
,
109Cd
, style="text-align:right" , 48
, style="text-align:right" , 61
, 108.904982(4)
, 461.4(12) d
, EC
,
109Ag
, 5/2+
,
,
, -
, style="text-indent:1em" ,
109m1Cd
, colspan="3" style="text-indent:2em" , 59.6(4) keV
, 12(2) µs
,
,
, 1/2+
,
,
, -
, style="text-indent:1em" ,
109m2Cd
, colspan="3" style="text-indent:2em" , 463.0(5) keV
, 10.9(5) µs
,
,
, 11/2
,
,
, -
,
110Cd
, style="text-align:right" , 48
, style="text-align:right" , 62
, 109.9030021(29)
, colspan=3 align=center, Stable
[Theoretically capable of spontaneous fission]
, 0+
, 0.1249(18)
,
, -
,
111Cd
[ Fission product]
, style="text-align:right" , 48
, style="text-align:right" , 63
, 110.9041781(29)
, colspan=3 align=center, Stable
, 1/2+
, 0.1280(12)
,
, -
, style="text-indent:1em" ,
111mCd
, colspan="3" style="text-indent:2em" , 396.214(21) keV
, 48.50(9) min
, IT
,
111Cd
, 11/2−
,
,
, -
,
112Cd
, style="text-align:right" , 48
, style="text-align:right" , 64
, 111.9027578(29)
, colspan=3 align=center, Stable
, 0+
, 0.2413(21)
,
, -
,
113Cd
[ Primordial radionuclide]
, style="text-align:right" , 48
, style="text-align:right" , 65
, 112.9044017(29)
, 8.04(5)×10
15 y
, β
−
,
113In
, 1/2+
, 0.1222(12)
,
, -
, rowspan=2 style="text-indent:1em" ,
113mCd
, rowspan=2 colspan="3" style="text-indent:2em" , 263.54(3) keV
, rowspan=2, 14.1(5) y
, β
− (99.86%)
,
113In
, rowspan=2, 11/2−
, rowspan=2,
, rowspan=2,
, -
, IT (.139%)
, ''
113Cd''
, -
,
114Cd
, style="text-align:right" , 48
, style="text-align:right" , 66
, 113.9033585(29)
, colspan=3 align=center, Observationally Stable
[Believed to undergo β−β− decay to 114Sn with a half-life over 6.4×1018 years]
, 0+
, 0.2873(42)
,
, -
,
115Cd
, style="text-align:right" , 48
, style="text-align:right" , 67
, 114.9054310(29)
, 53.46(5) h
, β
−
,
115mIn
, 1/2+
,
,
, -
, style="text-indent:1em" ,
115mCd
, colspan="3" style="text-indent:2em" , 181.0(5) keV
, 44.56(24) d
, β
−
,
115mIn
, (11/2)−
,
,
, -
,
116Cd
, style="text-align:right" , 48
, style="text-align:right" , 68
, 115.904756(3)
, 2.8(2)×10
19 y
, β
−β
−
,
116Sn
, 0+
, 0.0749(18)
,
, -
,
117Cd
, style="text-align:right" , 48
, style="text-align:right" , 69
, 116.907219(4)
, 2.49(4) h
, β
−
,
117mIn
, 1/2+
,
,
, -
, style="text-indent:1em" ,
117mCd
, colspan="3" style="text-indent:2em" , 136.4(2) keV
, 3.36(5) h
, β
−
,
117mIn
, (11/2)−
,
,
, -
,
118Cd
, style="text-align:right" , 48
, style="text-align:right" , 70
, 117.906915(22)
, 50.3(2) min
, β
−
,
118In
, 0+
,
,
, -
,
119Cd
, style="text-align:right" , 48
, style="text-align:right" , 71
, 118.90992(9)
, 2.69(2) min
, β
−
,
119mIn
, (3/2+)
,
,
, -
, style="text-indent:1em" ,
119mCd
, colspan="3" style="text-indent:2em" , 146.54(11) keV
, 2.20(2) min
, β
−
,
119mIn
, (11/2−)#
,
,
, -
,
120Cd
, style="text-align:right" , 48
, style="text-align:right" , 72
, 119.90985(2)
, 50.80(21) s
, β
−
,
120In
, 0+
,
,
, -
,
121Cd
, style="text-align:right" , 48
, style="text-align:right" , 73
, 120.91298(9)
, 13.5(3) s
, β
−
,
121mIn
, (3/2+)
,
,
, -
, style="text-indent:1em" ,
121mCd
, colspan="3" style="text-indent:2em" , 214.86(15) keV
, 8.3(8) s
, β
−
,
121mIn
, (11/2−)
,
,
, -
,
122Cd
, style="text-align:right" , 48
, style="text-align:right" , 74
, 121.91333(5)
, 5.24(3) s
, β
−
,
122In
, 0+
,
,
, -
,
123Cd
, style="text-align:right" , 48
, style="text-align:right" , 75
, 122.91700(4)
, 2.10(2) s
, β
−
,
123mIn
, (3/2)+
,
,
, -
, rowspan=2 style="text-indent:1em" ,
123mCd
, rowspan=2 colspan="3" style="text-indent:2em" , 316.52(23) keV
, rowspan=2, 1.82(3) s
, β
−
,
123In
, rowspan=2, (11/2−)
, rowspan=2,
, rowspan=2,
, -
, IT
,
123Cd
, -
,
124Cd
, style="text-align:right" , 48
, style="text-align:right" , 76
, 123.91765(7)
, 1.25(2) s
, β
−
,
124In
, 0+
,
,
, -
,
125Cd
, style="text-align:right" , 48
, style="text-align:right" , 77
, 124.92125(7)
, 0.65(2) s
, β
−
,
125mIn
, (3/2+)#
,
,
, -
, style="text-indent:1em" ,
125mCd
, colspan="3" style="text-indent:2em" , 50(70) keV
, 570(90) ms
, β
−
,
125In
, 11/2−#
,
,
, -
,
126Cd
, style="text-align:right" , 48
, style="text-align:right" , 78
, 125.92235(6)
, 0.515(17) s
, β
−
,
126In
, 0+
,
,
, -
,
127Cd
, style="text-align:right" , 48
, style="text-align:right" , 79
, 126.92644(8)
, 0.37(7) s
, β
−
,
127mIn
, (3/2+)
,
,
, -
,
128Cd
, style="text-align:right" , 48
, style="text-align:right" , 80
, 127.92776(32)
, 0.28(4) s
, β
−
,
128In
, 0+
,
,
, -
, rowspan=2,
129Cd
, rowspan=2 style="text-align:right" , 48
, rowspan=2 style="text-align:right" , 81
, rowspan=2, 128.93215(32)#
, rowspan=2, 242(8) ms
, β
− (>99.9%)
,
129In
, rowspan=2, 3/2+#
, rowspan=2,
, rowspan=2,
, -
, IT (<.1%)
,
129Cd
, -
, style="text-indent:1em" ,
129mCd
, colspan="3" style="text-indent:2em" , 0(200)# keV
, 104(6) ms
,
,
, 11/2−#
,
,
, -
, rowspan=2,
130Cd
, rowspan=2 style="text-align:right" , 48
, rowspan=2 style="text-align:right" , 82
, rowspan=2, 129.9339(3)
, rowspan=2, 162(7) ms
, β
− (96%)
,
130In
, rowspan=2, 0+
, rowspan=2,
, rowspan=2,
, -
, β
−, n (4%)
,
129In
, -
,
131Cd
, style="text-align:right" , 48
, style="text-align:right" , 83
, 130.94067(32)#
, 68(3) ms
,
,
, 7/2−#
,
,
, -
,
132Cd
, style="text-align:right" , 48
, style="text-align:right" , 84
, 131.94555(54)#
, 97(10) ms
,
,
, 0+
,
,
*
Hyperdeformation In nuclear physics, hyperdeformation is theoretically predicted states of an atomic nucleus with extremely elongated shape and very high angular momentum. Less elongated states, superdeformation, have been well observed, but the experimental evidenc ...
is predicted to be found in
107Cd.
Cadmium-113m
Cadmium-113m is a cadmium
radioisotope
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...
and
nuclear isomer
A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy higher energy levels than in the ground state of the same nucleus. "Metastable" describes nuclei whose excited states have ...
with a half-life of 14.1 years. In a normal
thermal reactor
A thermal-neutron reactor is a nuclear reactor that uses slow or thermal neutrons. ("Thermal" does not mean hot in an absolute sense, but means in thermal equilibrium with the medium it is interacting with, the reactor's fuel, moderator and struct ...
, it has a very low
fission product yield
Nuclear fission splits a heavy nucleus such as uranium or plutonium into two lighter nuclei, which are called fission products. Yield refers to the fraction of a fission product produced per fission.
Yield can be broken down by:
# Individual ...
, plus its large
neutron capture
Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, ...
cross section
Cross section may refer to:
* Cross section (geometry)
** Cross-sectional views in architecture & engineering 3D
*Cross section (geology)
* Cross section (electronics)
* Radar cross section, measure of detectability
* Cross section (physics)
**Abs ...
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
Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, rare-earth mining, and nuclear weapons ...
.
Fast fission
Fast fission is fission that occurs when a heavy atom absorbs a high-energy neutron, called a fast neutron, and splits. Most fissionable materials need thermal neutrons, which move more slowly.
Fast reactors vs. thermal reactors
Fast neutron re ...
or fission of some heavier
actinides
The actinide () or actinoid () series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium. The actinide series derives its name from the first element in the series, actinium. The inform ...
will produce
113mCd at higher yields.
References
* Isotope masses from:
**
* Isotopic compositions and standard atomic masses from:
**
**
* Half-life, spin, and isomer data selected from the following sources.
**
**
**
{{Authority control
Cadmium
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of ...