Isotopes of cadmium
Encyclopedia
Naturally occurring cadmium
(Cd) is composed of 8 isotope
s. 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
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.
Cadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
(Cd) is composed of 8 isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
s. 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
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
times. The two natural radioactive isotopes are 113Cd (beta decay
Beta decay
In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a...
, half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
is 7.7 × 1015 years) and 116Cd (two-neutrino double beta decay
Double beta decay
Double beta decay is a radioactive decay process where a nucleus releases two beta rays as a single process.In double-beta decay, two neutrons in the nucleus are converted to protons, and two electrons and two electron antineutrinos are emitted...
, half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
is 2.9 × 1019 years). The other three are 106Cd, 108Cd (double electron capture
Double electron capture
Double electron capture is a decay mode of atomic nucleus. For a nuclide with number of nucleons A and atomic number Z, double electron capture is only possible if the mass of the nuclide of is lower....
), and 114Cd (double beta decay
Double beta decay
Double beta decay is a radioactive decay process where a nucleus releases two beta rays as a single process.In double-beta decay, two neutrons in the nucleus are converted to protons, and two electrons and two electron antineutrinos are emitted...
); only lower limits on their half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
times have been set. At least three isotopes - 110Cd, 111Cd, and 112Cd - are absolutely stable (except, theoretically, to spontaneous fission
Spontaneous fission
Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses...
). 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
Atomic mass
The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....
from 94.950 u
Atomic mass unit
The unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...
(95Cd) to 131.946 u (132Cd). The primary decay mode before the second most abundant stable isotope, 112Cd, is electron capture
Electron capture
Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino...
and the primary modes after are beta emission and electron capture
Electron capture
Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino...
. The primary decay product
Decay product
In nuclear physics, a decay product is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps...
before 112Cd is element 47 (silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
) and the primary product after is element 49 (indium
Indium
Indium is a chemical element with the symbol In and atomic number 49. This rare, very soft, malleable and easily fusible post-transition metal is chemically similar to gallium and thallium, and shows the intermediate properties between these two...
).
Standard atomic mass: 112.411(8) u
Cadmium-113m
Cadmium-113m is a CadmiumCadmium
Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
radioisotope and nuclear isomer
Nuclear isomer
A nuclear isomer is a metastable state of an atomic nucleus caused by the excitation of one or more of its nucleons . "Metastable" refers to the fact that these excited states have half-lives more than 100 to 1000 times the half-lives of the other possible excited nuclear states...
with a halflife of 14.1 years. In a normal thermal reactor
Thermal reactor
A thermal reactor is a nuclear reactor that uses slow or thermal neutrons. Most power reactors are of this type. These type of reactors use a neutron moderator to slow neutrons until they approach the average kinetic energy of the surrounding particles, that is, to reduce the speed of the neutrons...
, it has a very low fission product yield
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 isotope...
, plus its large neutron capture
Neutron capture
Neutron capture is a kind of nuclear reaction in which an atomic nucleus collides with one or more neutrons and they merge to form a heavier nucleus. Since neutrons have no electric charge they can enter a nucleus more easily than positively charged protons, which are repelled...
cross section
Neutron cross-section
In nuclear and particle physics, the concept of a neutron cross section is used to express the likelihood of interaction between an incident neutron and a target nucleus. In conjunction with the neutron flux, it enables the calculation of the reaction rate, for example to derive the thermal power...
means that most of even the small amount produced is destroyed in the course of the nuclear fuel
Nuclear fuel
Nuclear fuel is a material that can be 'consumed' by fission or fusion to derive nuclear energy. Nuclear fuels are the most dense sources of energy available...
's burnup; thus, this isotope is not a significant contributor to nuclear waste.
Fast fission
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 slower.-Fast reactors vs. thermal reactors:...
or fission of some heavier actinides will produce 113mCd at higher yields.
Table
| nuclide symbol |
Z(p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... ) |
N(n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... ) |
isotopic mass (u) |
half-lifeBold for isotopes with half-lives longer than the age of the universe (nearly stable) | decay mode(s)Abbreviations: EC: Electron capture Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... IT: Isomeric transition Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
daughter isotope(s)Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe Age of the universe The age of the universe is the time elapsed since the Big Bang posited by the most widely accepted scientific model of cosmology. The best current estimate of the age of the universe is 13.75 ± 0.13 billion years within the Lambda-CDM concordance model... ) |
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+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a... |
96Ag | 0+ | ||
| 97Cd | 48 | 49 | 96.93494(43)# | 2.8(6) s | β+ (>99.9%) | 97Ag | 9/2+# | ||
| β+, p Proton emission Proton emission is a type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case the process is known as beta-delayed proton emission, or can occur from the ground state of very... (<.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 StableBelieved to decay by β+β+ to 106Pd with a half-life Half-life Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to... over 410×1018 years |
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 StableBelieved to decay by β+β+ to 108Pd with a half-life Half-life Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to... over 410×1015 years |
0+ | 0.0089(3) | |||
| 109Cd | 48 | 61 | 108.904982(4) | 461.4(12) d | EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... |
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) | Observationally StableTheoretically capable of spontaneous fission Spontaneous fission Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses... |
0+ | 0.1249(18) | |||
| 111CdFission product Fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus fissions. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons and a large release of energy in the form of heat , gamma rays and neutrinos. The... |
48 | 63 | 110.9041781(29) | Observationally Stable | 1/2+ | 0.1280(12) | |||
| 111mCd | 396.214(21) keV | 48.50(9) min | IT Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
111Cd | 11/2- | ||||
| 112Cd | 48 | 64 | 111.9027578(29) | Observationally Stable | 0+ | 0.2413(21) | |||
| 113CdPrimordial Primordial nuclide In geochemistry and geonuclear physics, primordial nuclides or primordial isotopes are nuclides found on the earth that have existed in their current form since before Earth was formed. Only 288 such nuclides are known... radionuclide Radionuclide A radionuclide is an atom with an unstable nucleus, which is a nucleus characterized by excess energy available to be imparted either to a newly created radiation particle within the nucleus or to an atomic electron. The radionuclide, in this process, undergoes radioactive decay, and emits gamma... |
48 | 65 | 112.9044017(29) | 7.7(3)×1015 a | β- | 113In | 1/2+ | 0.1222(12) | |
| 113mCd | 263.54(3) keV | 14.1(5) a | β- (99.86%) | 113In | 11/2- | ||||
| IT (.139%) | 113Cd | ||||||||
| 114Cd | 48 | 66 | 113.9033585(29) | Observationally StableBelieved to undergo β-β- decay to 114Sn with a half-life Half-life Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to... over 6.4×1018 years |
0+ | 0.2873(42) | |||
| 115Cd | 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 | 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+ | ||||