Naturally occurring

cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...

(Co) consists of a single stable

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 ...

, Co. Twenty-eight

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 ...

s have been characterized; the most stable are Co with a half-life of 5.2714 years, Co (271.8 days), Co (77.27 days), and Co (70.86 days). All other isotopes have half-lives less than 18 hours and most of these have half-lives less than 1 second. This element also has 11

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, all of which have half-lives less than 15 minutes. The isotopes of cobalt range in

atomic weight Relative atomic mass (symbol: ''A''; sometimes abbreviated RAM or r.a.m.), also known by the deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a giv ...

from Co to Co. The main decay mode for isotopes with atomic mass less than that of the stable isotope, Co, 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 main mode of decay for those of greater than 59 atomic mass units is

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 ...

. The main decay products before Co are

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

isotopes and the main products after are

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

isotopes. Radioactive isotopes can be produced by various

nuclear reaction In nuclear physics and nuclear chemistry, a nuclear reaction is a process in which two nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides. Thus, a nuclear reaction must cause a transformatio ...

s. For example, Co is produced by

cyclotron A cyclotron is a type of particle accelerator invented by Ernest O. Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: Jan ...

irradiation of iron. The main reaction is the (d,n) reaction Fe + H → n + Co.

List of isotopes

, - , ⁴⁷Co , style="text-align:right" , 27 , style="text-align:right" , 20 , 47.01149(54)# , , , , 7/2−# , , , - , ⁴⁸Co , style="text-align:right" , 27 , style="text-align:right" , 21 , 48.00176(43)# , , p , ⁴⁷Fe , 6+# , , , - , rowspan=2, ⁴⁹Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 22 , rowspan=2, 48.98972(28)# , rowspan=2, <35 ns , p (>99.9%) , ⁴⁸Fe , rowspan=2, 7/2−# , rowspan=2, , rowspan=2, , - , β⁺ (<.1%) , ⁴⁹Fe , - , rowspan=2, ⁵⁰Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 23 , rowspan=2, 49.98154(18)# , rowspan=2, 44(4) ms , β⁺, p (54%) , ⁴⁹Mn , rowspan=2, (6+) , rowspan=2, , rowspan=2, , - , β⁺ (46%) , ⁵⁰Fe , - , ⁵¹Co , style="text-align:right" , 27 , style="text-align:right" , 24 , 50.97072(16)# , 60# ms 200 ns, β⁺ , ⁵¹Fe , 7/2−# , , , - , ⁵²Co , style="text-align:right" , 27 , style="text-align:right" , 25 , 51.96359(7)# , 115(23) ms , β⁺ , ⁵²Fe , (6+) , , , - , rowspan=2 style="text-indent:1em" , ^52mCo , rowspan=2 colspan="3" style="text-indent:2em" , 380(100)# keV , rowspan=2, 104(11)# ms , β⁺ , ⁵²Fe , rowspan=2, 2+# , rowspan=2, , rowspan=2, , - , IT , ⁵²Co , - , ⁵³Co , style="text-align:right" , 27 , style="text-align:right" , 26 , 52.954219(19) , 242(8) ms , β⁺ , ⁵³Fe , 7/2−# , , , - , rowspan=2 style="text-indent:1em" , ^53mCo , rowspan=2 colspan="3" style="text-indent:2em" , 3197(29) keV , rowspan=2, 247(12) ms , β⁺ (98.5%) , ⁵³Fe , rowspan=2, (19/2−) , rowspan=2, , rowspan=2, , - , p (1.5%) , ⁵²Fe , - , ⁵⁴Co , style="text-align:right" , 27 , style="text-align:right" , 27 , 53.9484596(8) , 193.28(7) ms , β⁺ , ⁵⁴Fe , 0+ , , , - , style="text-indent:1em" , ^54mCo , colspan="3" style="text-indent:2em" , 197.4(5) keV , 1.48(2) min , β⁺ , ⁵⁴Fe , (7)+ , , , - , ⁵⁵Co , style="text-align:right" , 27 , style="text-align:right" , 28 , 54.9419990(8) , 17.53(3) h , β⁺ , ⁵⁵Fe , 7/2− , , , - , ⁵⁶Co , style="text-align:right" , 27 , style="text-align:right" , 29 , 55.9398393(23) , 77.233(27) d , β⁺ , ⁵⁶Fe , 4+ , , , - , ⁵⁷Co , style="text-align:right" , 27 , style="text-align:right" , 30 , 56.9362914(8) , 271.74(6) d , EC , ⁵⁷Fe , 7/2− , , , - , ⁵⁸Co , style="text-align:right" , 27 , style="text-align:right" , 31 , 57.9357528(13) , 70.86(6) d , β⁺ , ⁵⁸Fe , 2+ , , , - , style="text-indent:1em" , ^58m1Co , colspan="3" style="text-indent:2em" , 24.95(6) keV , 9.04(11) h , IT , ⁵⁸Co , 5+ , , , - , style="text-indent:1em" , ^58m2Co , colspan="3" style="text-indent:2em" , 53.15(7) keV , 10.4(3) μs , , , 4+ , , , - , ⁵⁹Co , style="text-align:right" , 27 , style="text-align:right" , 32 , 58.9331950(7) , colspan="3" style="text-align:center;", Stable , 7/2− , 1.0000 , , - , ⁶⁰Co , style="text-align:right" , 27 , style="text-align:right" , 33 , 59.9338171(7) , 5.2713(8) y , β⁻, γ , ⁶⁰Ni , 5+ , , , - , rowspan=2 style="text-indent:1em" , ^60mCo , rowspan=2 colspan="3" style="text-indent:2em" , 58.59(1) keV , rowspan=2, 10.467(6) min , IT (99.76%) , ⁶⁰Co , rowspan=2, 2+ , rowspan=2, , rowspan=2, , - , β⁻ (.24%) , ⁶⁰Ni , - , ⁶¹Co , style="text-align:right" , 27 , style="text-align:right" , 34 , 60.9324758(10) , 1.650(5) h , β⁻ , ⁶¹Ni , 7/2− , , , - , ⁶²Co , style="text-align:right" , 27 , style="text-align:right" , 35 , 61.934051(21) , 1.50(4) min , β⁻ , ⁶²Ni , 2+ , , , - , rowspan=2 style="text-indent:1em" , ^62mCo , rowspan=2 colspan="3" style="text-indent:2em" , 22(5) keV , rowspan=2, 13.91(5) min , β⁻ (99%) , ⁶²Ni , rowspan=2, 5+ , rowspan=2, , rowspan=2, , - , IT (1%) , ⁶²Co , - , ⁶³Co , style="text-align:right" , 27 , style="text-align:right" , 36 , 62.933612(21) , 26.9(4) s , β⁻ , ⁶³Ni , 7/2− , , , - , ⁶⁴Co , style="text-align:right" , 27 , style="text-align:right" , 37 , 63.935810(21) , 0.30(3) s , β⁻ , ⁶⁴Ni , 1+ , , , - , ⁶⁵Co , style="text-align:right" , 27 , style="text-align:right" , 38 , 64.936478(14) , 1.20(6) s , β⁻ , ⁶⁵Ni , (7/2)− , , , - , ⁶⁶Co , style="text-align:right" , 27 , style="text-align:right" , 39 , 65.93976(27) , 0.18(1) s , β⁻ , ⁶⁶Ni , (3+) , , , - , style="text-indent:1em" , ^66m1Co , colspan="3" style="text-indent:2em" , 175(3) keV , 1.21(1) μs , , , (5+) , , , - , style="text-indent:1em" , ^66m2Co , colspan="3" style="text-indent:2em" , 642(5) keV , >100 μs , , , (8-) , , , - , ⁶⁷Co , style="text-align:right" , 27 , style="text-align:right" , 40 , 66.94089(34) , 0.425(20) s , β⁻ , ⁶⁷Ni , (7/2−)# , , , - , ⁶⁸Co , style="text-align:right" , 27 , style="text-align:right" , 41 , 67.94487(34) , 0.199(21) s , β⁻ , ⁶⁸Ni , (7-) , , , - , style="text-indent:1em" , ^68mCo , colspan="3" style="text-indent:2em" , 150(150)# keV , 1.6(3) s , , , (3+) , , , - , rowspan=2, ⁶⁹Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 42 , rowspan=2, 68.94632(36) , rowspan=2, 227(13) ms , β⁻ (>99.9%) , ⁶⁹Ni , rowspan=2, 7/2−# , rowspan=2, , rowspan=2, , - , β⁻, n (<.1%) , ⁶⁸Ni , - , rowspan=2, ⁷⁰Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 43 , rowspan=2, 69.9510(9) , rowspan=2, 119(6) ms , β⁻ (>99.9%) , ⁷⁰Ni , rowspan=2, (6-) , rowspan=2, , rowspan=2, , - , β⁻, n (<.1%) , ⁶⁹Ni , - , style="text-indent:1em" , ^70mCo , colspan="3" style="text-indent:2em" , 200(200)# keV , 500(180) ms , , , (3+) , , , - , rowspan=2, ⁷¹Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 44 , rowspan=2, 70.9529(9) , rowspan=2, 97(2) ms , β⁻ (>99.9%) , ⁷¹Ni , rowspan=2, 7/2−# , rowspan=2, , rowspan=2, , - , β⁻, n (<.1%) , ⁷⁰Ni , - , rowspan=2, ⁷²Co , rowspan=2 style="text-align:right" , 27 , rowspan=2 style="text-align:right" , 45 , rowspan=2, 71.95781(64)# , rowspan=2, 62(3) ms , β⁻ (>99.9%) , ⁷²Ni , rowspan=2, (6- ,7-) , rowspan=2, , rowspan=2, , - , β⁻, n (<.1%) , ⁷¹Ni , - , ⁷³Co , style="text-align:right" , 27 , style="text-align:right" , 46 , 72.96024(75)# , 41(4) ms , , , 7/2−# , , , - , ⁷⁴Co , style="text-align:right" , 27 , style="text-align:right" , 47 , 73.96538(86)# , 50# ms 300 ns, , , 0+ , , , - , ⁷⁵Co , style="text-align:right" , 27 , style="text-align:right" , 48 , 74.96833(86)# , 40# ms 300 ns, , , 7/2−# , ,

Use of cobalt radioisotopes in medicine

Cobalt-57 (Co or Co-57) is used in medical tests; it is used as a radiolabel for vitamin B uptake. It is useful for the

Schilling test The Schilling test was a medical investigation used for patients with vitamin B (cobalamin) deficiency. The purpose of the test was to determine how well a patient is able to absorb B12 from their intestinal tract. The test is now considered obs ...

. Cobalt-60 (Co or Co-60) is used in radiotherapy. It produces two gamma rays with energies of 1.17

MeV In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacu ...

and 1.33 MeV. The Co source is about 2 cm in

diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid fo ...

and as a result produces a geometric penumbra, making the edge of the radiation field fuzzy. The metal has the unfortunate habit of producing a fine dust, causing problems with radiation protection. The Co source is useful for about 5 years but even after this point is still very radioactive, and so cobalt machines have fallen from favor in the Western world where linacs are common.

Industrial uses for radioactive isotopes

Cobalt-60 (Co) is useful as a gamma ray source because it can be produced in predictable quantities, and for its high radioactivity simply by exposing natural cobalt to

neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...

s in a reactor. The uses for industrial cobalt include: *Sterilization of medical supplies and medical waste *Radiation treatment of foods for sterilization (cold pasteurization) *Industrial

radiography Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeu ...

(e.g., weld integrity radiographs) *Density measurements (e.g., concrete density measurements) *Tank fill height switches Cobalt-57 is used as a source in

Mössbauer spectroscopy Mössbauer spectroscopy is a spectroscopic technique based on the Mössbauer effect. This effect, discovered by Rudolf Mössbauer (sometimes written "Moessbauer", German: "Mößbauer") in 1958, consists of the nearly recoil-free emission and abs ...

of iron-containing samples. Electron capture by Co forms an excited state of the Fe nucleus, which in turn decays to the ground state with emission of a gamma ray. Measurement of the gamma ray spectrum provides information about the chemical state of the iron atom in the sample.

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes Cobalt

Cobalt Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, p ...