Cobalt

Symbol

Co

Atomic number

27

Atomic mass	58.9332		Thermal conductivity	1.00
Atomic radius	1.67		Covalent radius	1.16
Density	8.90		Atomic volume	6.7
Melting point	1768		Oxidation states	2,3
Boiling point	3143		Stable isotopes	1
Heat of vapor.	376.50		Electronegativity	1.88
Heat of fusion	16.190		First ionization	7.86
Specific heat	0.42		Electrical conduct.	...

Electron configuration

Cobalt

Cobalt is a silvery-white metal, with a slight reddish tinge. It occurs in the minerals smaltite and safflorite with the composition CoAs₂. Cobalt also forms an arsenide with the content CoAs_2-3 which is called skutterudite. The sulfide mineral cobaltite, CoAsS, also occurs. Cobalt is usually found in association with nickel. Cobalt forms the sulfide mineral linnaeite, Co₃S₄. Copper, cobalt and nickel join in the sulfide carrollite, Cu(Co,Ni)₂S₄. Cobalt joins with iron and arsenic in the sulfide glaucodot, (Co,Fe)AsS.

Cobalt is used to produce the strongly ferromagnetic alloy alnico which is used to make strong permanent magnets. Alnico alloys iron, nickel, cobalt and aluminum.

Cobalt chloride (CoCl₂.6H₂O) forms red crystals which turn blue when dehydrated. Cobalt oxide, CoO, is a black powder, but it gives a blue color to glass when dissolved in it (cobalt glass).

Cobalt Nuclear Data

The decay of cobalt-57 by electron capture produces an excited state of iron-57 which emits gamma rays to reach its ground state. One of those transitions has become very important for Mossbauer effect studies.