| Cobalt - Co
CAS: 7440-48-4 Description: Tough, silver-white metal Classification: Transition Metal Date of Discovery: 1737 Discoverer: George Brandt Name Origin: German kobald "goblin or evil spirit"; Greek cobalos "mine" |
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Atomic Number: 27
Number of Neutrons: 32 Atomic Mass: 58.93320(1) amu Melting Point: 1495 °C Boiling Point: 2927 °C Density (293 K): 8.9 g/cm3 Atomic volume: 6.7 cm3/mol Electrical resistivity: 0.172 10-6/cm 
Thermal conductivity: 1.00 W/cmK Enthalpy of atomization: 426.77 kJ/mol Enthalpy of vaporization: 376.50 kJ/mol Enthalpy of fusion: 16.190 kJ/mol Specific heat capacity: 0.42 J/gK |
Energy levels: 2-8-15-2
Electron configuration: [Ar]3d74s2 Crystal Structure: Hexagonal Atomic radius: 1.67 Å Covalent radius: 1.16 Å Oxidation States: +2, +3 Electronegativity, Pauling: 1.88 Electron affinity: 0.662 eV First ionization energy: 7.86 eV 2nd ionization energy: 17.06 eV 3rd ionization energy: 33.50 eV Polarizability: 7.5 10-24cm3 |
| Isotope | Natural Abundance | Atomic Mass | Half-life | Decay Mode | Spin |
| 50Co | 49.9812 |  + |
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| 51Co | 50.9705 | + |
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| 52Co | 51.9632 | + |
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| 53mCo | 0.25 s | +, p |
19/2- | ||
| 53Co | 52.95423 | 0.26 s | + |
7/2- | |
| 54mCo | 1.46 m | + |
7+ | ||
| 54Co | 53.948464 | 0.1932 s | + |
0+ | |
| 55Co | 54.942003 | 17.53 h | +; EC |
7/2 | |
| 56Co | 55.939844 | 77.3 d | +; EC |
4+ | |
| 57Co | 56.936296 | 271.8 d | EC | 7/2 | |
| 58mCo | 9.1 h | IT | 5+ | ||
| 58Co | 57.935757 | 70.88 d | +; EC |
2+ | |
| 59Co | 100. | 58.933200 | Stable | 7/2- | |
| 60mCo | 10.47 m | IT;- |
2+ | ||
| 60Co | 59.933822 | 5.271 y | - |
5+ | |
| 61Co | 60.932479 | 1.650 h | - |
7/2- | |
| 62mCo | 13.9 m | - |
5+ | ||
| 62Co | 61.93405 | 1.50 m | - |
2+ | |
| 63Co | 62.93362 | 27.5 s | - |
7/2- | |
| 64Co | 63.93581 | 0.30 s | - |
1+ | |
| 65Co | 64.93648 | 1.14 s | - |
(7/2-) | |
| 66Co | 65.9398 |  0.23 s |
- |
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| 67Co | 66.9406 | - |
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| 68Co | 67.9444 | 0.18 s |
- |
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| 69Co | 68.9452 | 0.27 s | - |
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| 70Co | 69.9498 | - |
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| 71Co | |||||
Discovered by Brandt about 1735. Cobalt occurs in the mineral cobaltite (CoAsS), smaltite [skutterudite, (Co,Ni)As3-x], erythrite [Co3(AsO4)2 · 8H2O], and linneite (Co3S4) 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 cloase to the the Hawaiian Islands and other U.S. Pacific territories. Cobalt is a brittle, hard metal, closely 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 -form predominates below 400 °C, and the  -form above that temperature. The transformation is sluggish and accounts in part for the wide variation in reported data on physical properties of cobalt. 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. The salts have been used for centuries for the production of 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 (CoCl2 · 6H20) is used as a sympathetic ink. The cobalt amines are of interest; the oxide and the nitrate are important. 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-60, an artificial isotope, is an important gamma ray source, and is extensively used as a tracer and a radiotherapeutic agent. Twenty-six isotopes and isomers are known.
LINKS: Banff Resources Ltd: Facts About Cobalt Cobalt Chemicals Cobalt-60 Gamma Cell Irradiation Facility, WCNS Nuclear Lunch: The Dangers and Unknowns of Food Irradiation Telmag Ltd - Nickel & Cobalt Iron GB Return
Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998. |
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