| Group | 9 | Melting point | 1495 oC, 2723 oF, 1768.15 K |
| Period | 4 | Boiling point | 2927 oC, 5300.6 oF, 3200.15 K |
| Block | d | Density (kg m-3) | 8800 |
| Atomic number | 27 | Relative atomic mass | 58.933 |
| State at room temperature | Solid | Key isotopes | 59Co |
| Electron configuration | [Ar] 3d74s2 | CAS number | 7440-48-4 |
| ChemSpider ID | 94547 | ChemSpider is a free chemical structure database | |
Image explanation
A goblin or “kobold” (often accused of leading German miners astray in their search for Tin) against a backdrop of early Chinese porcelain using the element as a now familiar blue glaze.
Appearance
A lustrous, silvery metal with a blue cast. It can be magnetised like iron and so is used to make magnets, as well as in ceramics and paints. The radioactive isotope cobalt-60 is used in medical treatment and, in some countries, to irradiate food to preserve it. Cobalt is an essential element for humans since it is part of vitamin B12. The amount needed is very small, and the body contains only about 1 milligramme.
Uses
Cobalt metal is used in electroplating because of its attractive appearance, hardness and resistance to oxidation. It is alloyed with iron, nickel and other metals, and used in jet turbines and gas turbine generators. Cobalt salts have been used for centuries to produce brilliant blue colours in porcelain, glass, pottery and enamels. It can be magnetised like iron and so is used to make magnets, as well as in ceramics and paints. Radioactive cobalt-60 is used in the treatment of cancer.
Biological role
Cobalt is an essential trace element, and forms part of the active site of vitamin B12. The amount needed is very small, and the body contains only about 1 milligramme. Cobalt salts in small doses have been found to be effective in correcting mineral deficiencies in certain animals. Cobalt in large doses is carcinogenic. Radioactive artificial cobalt-60 is an important gamma-ray source, and is used extensively as a tracer and radiotherapeutic agent. The radioactive isotope cobalt-60 is sometimes used in some countries to irradiate food to preserve it.
Natural abundance
Cobalt is found in the minerals cobaltite, smaltite and erythrite. Important ore deposits are found in Zaire, Morocco and Canada. There is evidence that the floor of the north central Pacific Ocean may have cobalt-rich deposits.
| Atomic radius, non-bonded (Å) | 2.000 | Covalent radius (Å) | 1.18 |
| Electron affinity (kJ mol-1) | 63.851 |
Electronegativity (Pauling scale) |
1.880 |
|
Ionisation energies (kJ mol-1) |
1st
760.400
2nd
1648.354
3rd
3232.256
4th
4949.694
5th
7670.578
6th
9841.496
7th
12436.950
8th
15225.374
|
||
|
|
| Common oxidation states | 3, 2, 0, -1 | ||||
| Isotopes | Isotope | Atomic mass | Natural abundance (%) | Half life | Mode of decay |
| 59Co | 58.933 | 100 | - | - | |
|
Molar heat capacity (J mol-1 K-1) |
24.81 | Young's modulus (GPa) | Unknown | |||||||||||
| Shear modulus (GPa) | Unknown | Bulk modulus (GPa) | Unknown | |||||||||||
| Vapour pressure | ||||||||||||||
| Temperature (K) |
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| Pressure (Pa) |
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Videos of the elements. Additional videos will be coming in 2012.
Images: Visual Elements © Murray Robertson 2011
Mining and Sourcing data: British Geological Survey – natural environment research council.
Text: John Emsley Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, 2nd Edition, 2011.
Data: CRC Handbook of Chemistry and Physics, CRC Press, 92nd Edition, 2011.
G. W. C. Kaye and T. H. Laby Tables of Physical and Chemical Constants, Longman, 16th Edition, 1995.
Members of the RSC can access these books through our library.
Mining and Sourcing data: British Geological Survey – natural environment research council.
Text: John Emsley Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, 2nd Edition, 2011.
Data: CRC Handbook of Chemistry and Physics, CRC Press, 92nd Edition, 2011.
G. W. C. Kaye and T. H. Laby Tables of Physical and Chemical Constants, Longman, 16th Edition, 1995.
Members of the RSC can access these books through our library.
