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 numbers) ...

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 × 10¹⁵ 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 × 10¹⁹ 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. I ...

), 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 Spontaneous fission (SF) is a form of radioactive decay that is found only in very heavy chemical elements. The nuclear binding energy of the elements reaches its maximum at an atomic mass number of about 56 (e.g., iron-56); spontaneous breakdo ...

). 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 ha ...

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&nbs ...

from 94.950 u (⁹⁵Cd) to 131.946 u (¹³²Cd). The primary

decay mode Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...

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 In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( ...

before ¹¹²Cd is element 47 (

silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...

) 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 p ...

). 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 StableBelieved 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, StableTheoretically capable of spontaneous fission , 0+ , 0.1249(18) , , - , ¹¹¹Cd

Fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release ...

, 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 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; transfer ...

, style="text-align:right" , 48 , style="text-align:right" , 65 , 112.9044017(29) , 8.04(5)×10¹⁵ 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 StableBelieved 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)×10¹⁹ 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 excited state, higher energy levels than in the ground state of the same nucleus. "Metastable" describes nuclei whose excited ...

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 Nuclear fuel is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission. Most nuclear fuels contain heavy fissile actinide elements that are capable of undergoing ...

'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 r ...

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 reac ...

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 ...