| Atomic Mass | 58.933194 |
|---|---|
| Electron Configuration | [Ar]4s23d7 |
| Oxidation States | +3, +2 |
| Year Discovered | 1735 |
| Atomic Mass | 58.933194 |
|---|---|
| Electron Configuration | [Ar]4s23d7 |
| Oxidation States | +3, +2 |
| Year Discovered | 1735 |
| Element Name | Cobalt |
|---|---|
| Element Symbol | Co |
| InChI | InChI=1S/Co |
| InChIKey | GUTLYIVDDKVIGB-UHFFFAOYSA-N |
| Atomic Weight |
58.933 194(3) 58.933194 58.93 58.933194(4) |
|---|---|
| Electron Configuration |
[Ar]4s23d7 |
| Atomic Radius |
Van der Waals Atomic Radius : 192 pm (Van der Waals) Empirical Atomic Radius : 135pm (Empirical) Covalent Atomic Radius : 126(3)[l.s.], 150(7)[h.s.] pm (Covalent) |
| Oxidation States |
+3, +2 -3, -1, +1, +2, +3, +4, +5 (an amphoteric oxide) |
| Ground Level |
4F9/2 |
| Ionization Energy |
7.881 eV 7.88101 ± 0.00012 eV |
| Electronegativity |
Pauling Scale Electronegativity : 1.88(Pauling Scale) Allen Scale Electronegativity : 1.84(Allen Scale) |
| Electron Affinity |
0.661eV 1.06eV |
| Atomic Spectra |
Lines Holdings Levels Holdings |
| Physical Description |
Solid |
| Element Classification |
Metal |
| Element Period Number |
4 |
| Element Group Number |
9 |
| Density |
8.86 grams per cubic centimeter |
| Melting Point |
1768 K (1495°C or 2723°F) 1495°C |
| Boiling Point |
3200 K (2927°C or 5301°F) 2927°C |
| Estimated Crustal Abundance |
2.5×101 milligrams per kilogram |
| Estimated Oceanic Abundance |
2×10-5 milligrams per liter |
The name derives from the German Kobold for "evil spirits" or "goblins", who were superstitiously thought to cause trouble for miners because the mineral contained arsenic that injured their health and the metallic ores did not yield metals when treated with the normal methods. Cobalt was discovered in 1735 by the Swedish chemist Georg Brandt.
Cobalt was discovered by Georg Brandt, a Swedish chemist, in 1739. Brandt was attempting to prove that the ability of certain minerals to color glass blue was due to an unknown element and not to bismuth, as was commonly believed at the time. Cobalt's primary ores are cobaltite (CoAsS) and erythrite (Co3(AsO4)2). Cobalt is usually recovered as a byproduct of mining and refining nickel, silver, lead, copper and iron.
From the German word Kobald, goblin or evil spirit; also from the Greek cobalos, mine. George Brandt discovered cobalt in 1735.
| Year | Atomic Weight (uncertainty) [u] | Reference |
|---|---|---|
| 2017 | 58.933 194(3) | https://doi.org/10.1515/pac-2019-0603 |
| 2013 | 58.933 194(4) | https://doi.org/10.1515/pac-2015-0305 |
| 2005 | 58.933 195(5) | https://doi.org/10.1351/pac200678112051 |
| 1995 | 58.933 200(9) | https://doi.org/10.1351/pac199668122339 |
| 1985 | 58.933 20(1) | https://doi.org/10.1351/pac198658121677 |
| 1969 | 58.9332(1) | https://doi.org/10.1351/pac197021010091 |
| 1961 | 58.9332 | https://doi.org/10.1021/ja00881a001 |
| 1925 | 58.94 | https://doi.org/10.1039/CT9252700913 |
| 1909 | 58.97 | https://doi.org/10.1021/ja01931a001 |
| 1902 | 59.0 | https://doi.org/10.1007/BF01370337 |
| Year | Isotope | Abundance (uncertainty) | Reference |
|---|
| 1975, 59Co, 1, doi:10.1351/pac197647010075 |
Cobalt is a brittle, hard metal, resembling iron and nickel in appearance. It has a metallic permeability of about two thirds that of iron. Cobalt tends to exist as a mixture of two allotropes over a wide temperature range. The transformation is sluggish and accounts in part for the wide variation in reported data on physical properties of cobalt.
Although cobalt is used in electroplating to give objects an attractive surface that resists oxidation, it is more widely used to form alloys. Alnico, an alloy consisting of aluminum, nickel and cobalt is used to make powerful permanent magnets. Stellite alloys, which contain cobalt, chromium and tungsten, are used to make high-speed and high temperature cutting tools and dyes. Cobalt is also used to make alloys for jet engines and gas turbines, magnetic steels and some types of stainless steels.
Cobalt-60, a radioactive isotope of cobalt, is an important source of gamma rays and is used to treat some forms of cancer and as a medical tracer. Cobalt-60 has a half-life of 5.27 years and decays into nickel-60 through beta decay.
Cobalt compounds have been used for centuries to color porcelain, glass, pottery, tile and enamel. Some of these compounds are known as: cobalt blue, ceruleum, new blue, smalt, cobalt yellow and cobalt green. In addition to being used as a dye, cobalt is also important to human nutrition as it is an essential part of vitamin B12.
It is alloyed with iron, nickel and other metals to make Alnico, an alloy of unusual magnetic strength with many important uses. Stellite alloys, containing cobalt, chromium, and tungsten, are used for high-speed, heavy-duty, high temperature cutting tools, and for dies.
Cobalt is also used in other magnetic steels and stainless steels, and in alloys used in jet turbines and gas turbine generators. The metal is used in electroplating because of its appearance, hardness, and resistance to oxidation.
Cobalt salts have been used for centuries to produce brilliant and permanent blue colors in porcelain, glass, pottery, tiles, and enamels. It is the principal ingredient in Sevre's and Thenard's blue. A solution of the chloride is used as a sympathetic ink. Cobalt carefully used in the form of the chloride, sulfate, acetate, or nitrate has been found effective in correcting a certain mineral deficiency disease in animals.
Soils should contain 0.13 to 0.30 ppm of cobalt for proper animal nutrition.
Cobalt occurs in the minerals cobaltite, smaltite, and erythrite, and is often associated with nickel, silver, lead, copper, and iron ores, from which it is most frequently obtained as a by-product. It is also present in meteorites.
Important ore deposits are found in Zaire, Morocco, and Canada. The U.S. Geological Survey has announced that the bottom of the north central Pacific Ocean may have cobalt-rich deposits at relatively shallow depths in water close to the the Hawaiian Islands and other U.S. Pacific territories.
See more information at the Cobalt compound page.
| CID | Name | Formula | SMILES | Molecular Weight |
|---|---|---|---|---|
| 104730 | cobalt | Co | [Co] | 58.93319 |
| 104729 | cobalt(2+) | Co+2 | [Co+2] | 58.93319 |
| 61492 | cobalt-60 | Co | [60Co] | 59.933816 |
| 105146 | cobalt(3+) | Co+3 | [Co+3] | 58.93319 |
| 104844 | cobalt-58 | Co | [58Co] | 57.93575 |
| 104851 | cobalt-57 | Co | [57Co] | 56.936290 |
| 166968 | cobalt-55 | Co | [55Co] | 54.941996 |
| 166998 | cobalt-56 | Co | [56Co] | 55.939838 |
| 71510781 | cobalt-57(2+) | Co+2 | [57Co+2] | 56.936290 |
| 182512 | cobalt-60(2+) | Co+2 | [60Co+2] | 59.933816 |
| 71510783 | cobalt-58(2+) | Co+2 | [58Co+2] | 57.93575 |
| 177473 | cobalt-62 | Co | [62Co] | 61.9341 |
| 178158 | cobalt-61 | Co | [61Co] | 60.932476 |
| 11528329 | cobalt-59 | Co | [59Co] | 58.933194 |
| 156022700 | cobalt-59(3+) | Co+3 | [59Co+3] | 58.933194 |
Exposure to cobalt (metal fumes and dust) should be limited to 0.05 mg/m3 (8-hour time-weighted average 40-hour week).
| Stable Isotope Count | 1 |
|---|---|
| Summary | Cobalt-60, an artificial isotope, is an important gamma ray source, and is extensively used as a tracer and a radiotherapeutic agent. |
60Co (with a half-life of 5.27 years) is used to irradiate food sources as a method of preserving food (Fig. IUPAC.27.1). The gamma radiation from 60Co kills bacteria and other organisms that cause disease and spoilage of food (see Fig. IUPAC.27.1). The use of radioactive compounds for preserving food is not always viewed positively. Some individuals are concerned that harmful compounds will be produced during the irradiation process. However, there is no evidence to support the claim that irradiation is dangerous for food preservation [108]. Many medical products today are sterilized using gamma rays from a 60Co source. This technique of sterilization is generally much cheaper and more effective than steam-heat sterilization because it is a cold process. For example, it can be performed on packaged items, such as disposable syringes. This sterilization technique is applicable to a wide range of heat-sensitive items, such as powders, ointments, and solutions, as well as biological preparations, such as bone, nerve, skin, etc., used in tissue grafts [108].
60Co is also used in industrial radiography to detect structural flaws in metal parts. The radiation can penetrate metals and the X-ray pattern produced by the radiating material can provide information on its strength, composition, and other properties [108]. Because of the above property, 60Co is also used in leveling devices and thickness gauges used to test welds and castings [108].
![Fig. IUPAC.27.1: Plants growing in the gamma greenhouse at Brookhaven National Laboratory. The plants are arranged in concentric rings around the radioactive ⁶⁰Co source, which is in the pipe extending into the floor (circa 1959) [223]. (Photo Source: Life Sciences Foundation (LSF) Magazine).](https://pubchem.ncbi.nlm.nih.gov/images/iupac/j_pac-2015-0703_fig_043.jpg)
60Co is a radioactive metal isotope that is used in cancer treatments by radiotherapy. When 60Co undergoes radioactive decay, high-energy gamma rays (energies of 1.17 MeV and 1.33 MeV) are emitted and have been used in brachytherapy to treat various types of cancer. Brachytherapy (brachy is Greek meaning “short distance”) is a method of radiation treatment in which sealed sources are used to deliver a radiation dose at a distance of up to a few centimeters by surface, intracavitary (insertion of the radioactive isotope in a body cavity), or interstitial (between cells) application [75]. 60Co is used as a source of high-energy ionizing gamma radiation that can be directed to cancer cells from a device outside the body (external radiotherapy).
60Co (and sometimes 57Co and 58Co, with half-lives of 0.75 year and 71 days, respectively) is the key component of the Schilling test, which is a method for determining whether a patient’s body is making and using vitamin B12 properly. The cobalt isotope is used to label cobalt in vitamin B12 to monitor how the body processes this essential vitamin [224].
57Co delivers the smallest radiation dose of all the cobalt isotopes. As a result, it has been used in the past for imaging and estimating organ size and location and in evaluating tumors of the head and neck [75], [99], [225], [226], [227].
| Isotope | Atomic Mass (uncertainty) [u] | Abundance (uncertainty) |
|---|---|---|
| 59Co | 58.933 194(3) | 1 |
| Isotope | Atomic Mass (uncertainty) [u] | Abundance (uncertainty) |
|---|---|---|
| 59Co | 58.93319429(56) | 1 |
| Nuclide | Atomic Mass and Uncertainty [u] | Half Life and Uncertainty | Discovery Year | Decay Modes, Intensities and Uncertainties [%] |
|---|---|---|---|---|
| 47Co | 47.011401 ± 0.000644 [Estimated] | Not-specified | p ? | |
| 48Co | 48.001857 ± 0.000537 [Estimated] | Not-specified | p ? | |
| 49Co | 48.989501 ± 0.000537 [Estimated] | Not-specified <35ns | p ? | |
| 50Co | 49.981117000 ± 0.000135 | 38.8 ms ± 0.2 | 1987 | β+=100%; β+p=70.5±0.7%; β+2p ? |
| 51Co | 50.970647000 ± 0.000052 | 68.8 ms ± 1.9 | 1987 | β+=100%; β+p<3.8% |
| 52Co | 51.963130224 ± 0.000005669 | 111.7 ms ± 2.1 | 1987 | β+=100%; β+p ? |
| 52Com | 51.963130224 ± 0.000005669 | 102 ms ± 5 | 2016 | β+≈100%; IT ?; β+p ? |
| 53Co | 52.954203278 ± 0.000001854 | 244.6 ms ± 2.8 | 1970 | β+=100% |
| 53Com | 52.954203278 ± 0.000001854 | 250 ms ± 10 | 1970 | β+=?; p≈1.5% |
| 54Co | 53.948459075 ± 0.00000038 | 193.27 ms ± 0.06 | 1952 | β+=100% |
| 54Com | 53.948459075 ± 0.00000038 | 1.48 m ± 0.02 | 1962 | β+=100% |
| 55Co | 54.941996416 ± 0.000000434 | 17.53 h ± 0.03 | 1938 | β+=100% |
| 56Co | 55.939838032 ± 0.00000051 | 77.236 d ± 0.026 | 1941 | β+=100% |
| 57Co | 56.936289819 ± 0.000000553 | 271.811 d ± 0.032 | 1941 | ε=100% |
| 58Co | 57.935751292 ± 0.000001237 | 70.844 d ± 0.020 | 1941 | β+=100%; e+=14.79±2.4%; ε=85.21±2.4% |
| 58Com | 57.935751292 ± 0.000001237 | 8.853 h ± 0.023 | 1950 | IT=99.99880±0.5%; ε=0.00120±0.5% |
| 58Con | 57.935751292 ± 0.000001237 | 10.5 us ± 0.3 | 1964 | IT=100% |
| 59Co | 58.933193524 ± 0.000000426 | Stable | 1923 | IS=100% |
| 60Co | 59.933815536 ± 0.000000433 | 5.2714 y ± 0.0006 | 1941 | β-=100% |
| 60Com | 59.933815536 ± 0.000000433 | 10.467 m ± 0.006 | 1963 | IT≈100%; β-=0.25±0.3% |
| 61Co | 60.932476031 ± 0.000000901 | 1.649 h ± 0.005 | 1947 | β-=100% |
| 62Co | 61.934058198 ± 0.00001994 | 1.54 m ± 0.10 | 1949 | β-=100% |
| 62Com | 61.934058198 ± 0.00001994 | 13.86 m ± 0.09 | 1957 | β-≈100%; IT<0.5% |
| 63Co | 62.933599630 ± 0.000019941 | 26.9 s ± 0.4 | 1960 | β-=100% |
| 64Co | 63.935810176 ± 0.000021476 | 300 ms ± 30 | 1969 | β-=100% |
| 64Com | 63.935810176 ± 0.000021476 | 300 ms [Estimated] | 2008 | β- ?; IT ? |
| 65Co | 64.936462071 ± 0.000002235 | 1.16 s ± 0.03 | 1978 | β-=100% |
| 66Co | 65.939442943 ± 0.000015 | 194 ms ± 17 | 1985 | β-=100%; β-n ? |
| 66Com | 65.939442943 ± 0.000015 | 824 ns ± 22 | 1998 | IT=100% |
| 66Con | 65.939442943 ± 0.000015 | >100 us | 1998 | IT=100% |
| 67Co | 66.940609625 ± 0.000006917 | 329 ms ± 28 | 1985 | β-=100%; β-n ? |
| 67Com | 66.940609625 ± 0.000006917 | 496 ms ± 33 | 2008 | IT>80%; β- ? |
| 68Co | 67.944559401 ± 0.000004142 | 200 ms ± 20 | 1985 | β-=100%; β-n ? |
| 68Com | 67.944559401 ± 0.000004142 | 1.6 s ± 0.3 | 1998 | β-=100%; β-n>2.6% |
| 68Con | 67.944559401 ± 0.000004142 | 101 ns ± 10 | 2010 | IT=100% |
| 69Co | 68.945909000 ± 0.000092 | 180 ms ± 20 | 1985 | β-=100%; β-n ? |
| 69Com | 68.945909000 ± 0.000092 | 750 ms ± 250 | 2015 | β-=100% |
| 70Co | 69.950053400 ± 0.0000118 | 508 ms ± 7 | 1998 | β-=100%; β-n ?; β-2n ? |
| 70Com | 69.950053400 ± 0.0000118 | 112 ms ± 7 | 1985 | β-=100%; IT ?; β-n ?; β-2n ? |
| 71Co | 70.952366923 ± 0.00049923 | 80 ms ± 3 | 1992 | β-=100%; β-n=3±0.1% |
| 72Co | 71.956736 ± 0.000322 [Estimated] | 51.5 ms ± 0.3 | 1992 | β-=100%; β-n>4%; β-2n ? |
| 72Com | 71.956736 ± 0.000322 [Estimated] | 47.8 ms ± 0.5 | 2016 | β-=100% |
| 73Co | 72.959238 ± 0.000322 [Estimated] | 42.0 ms ± 0.8 | 1995 | β-=100%; β-n=6±0.3%; β-2n ? |
| 74Co | 73.963993 ± 0.000429 [Estimated] | 31.3 ms ± 1.3 | 1995 | β-=100%; β-n=18±1.5%; β-2n ? |
| 75Co | 74.967192 ± 0.000429 [Estimated] | 26.5 ms ± 1.2 | 1995 | β-=100%; β-n<16%; β-2n ? |
| 76Co | 75.972453 ± 0.000537 [Estimated] | 23 ms ± 6 | 2010 | β-=100%; β-n ?; β-2n ? |
| 76Com | 75.972453 ± 0.000537 [Estimated] | 16 ms ± 4 | 2015 | β-=100% |
| 76Con | 75.972453 ± 0.000537 [Estimated] | 2.99 us ± 0.27 | 2015 | IT=100% |
| 77Co | 76.976479 ± 0.000644 [Estimated] | 15 ms ± 6 | 2014 | β-=100%; β-n ?; β-2n ?; β-3n ? |
| 78Co | 77.983553 ± 0.000751 [Estimated] | 11 ms >410ns [Estimated] | 2017 | β- ? |
