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CoCo at. wt. 58.9332 at. no. 27 m.p. 1495°C b.p. 2870°C sp. gr. 8.9 (20°C) valence 2 or 3.
| SHELL | K | L | M | N | O | P | Q |
| SUB SHELL | He | Neon | Argon | Krypton | Xenon | Radon | Eka-radon |
| 1s | 2s 2p | 3s 3p | 3d 4s 4p | 4d 5s 5p | 4f 5d 6s 6p | 5f 6d 7s 7p | |
| Cobalt | 1s22s22p63s23p63d74s2 | ||||||
| Symbol | 4F9/2 | ||||||
Cobalt was discovered by Brandt about 1735. 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 the Congo, Morocco, and Canada. Cobalt is a brittle, hard metal, closely resembling iron and nickel in appearance. It has a magnetic permeability of about two- thirds that of iron. Cobalt tends to exist as a mixture of two allotropes over a wide temperature range. The fl-form predominates below 4000C and the a 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 magnet 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 per- manent blue colors in porcelain, glass, pottery, tiles and enamels. It is the principal ingredient in Serves and Thenard's blue. A solution of the chloride (CoCI2 6H20) is used as sympathetic ink. The cobalt ammines are of interest; the oxide and the nitrate are important. Cobalt carefully used in the form of the chloride, sulfate, acetate, or nitrate has beeh 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 radio-therapeutic agent. Single com- pact sources of Cobalt-60, are readily available and have an equivalent gamma ray output equal to thousands of grams of radium. The cost of Cobalt-60 varies from about 40~ to $7.00/curie, depending on quantity and specific activity.
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