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Cobalt

Source of the photo
http://www.periodictable.com/Samples/027.14/index.s12.html
Author of the description
Gruiz Katalin

Atomic number

27

Atomic mass

58.9332 g.mol -1

Electronegativity

1.8

Density

8.9 g.cm-3 at 20°C

Melting point

1495 °C

Boiling point

2927 °C

Vanderwaals radius

0.125 nm

Ionic radius

0.078 nm (+2) ; 0.063 nm (+3)

Isotopes

8

Electronic shell

[ Ar ] 3d7 4s2

Energy of first ionisation

757 kJ.mol -1

Energy of second ionisation

1666.3 kJ.mol -1

Energy of third ionisation

3226 kJ.mol -1

Standard potential

- 0.28 V ( Co2+/ Co ) ; +1.84 V ( Co3+/ Co2+ )

Discovered by

George Brandt in 1737

 

 

Cobalt is a hard ferromagnetic, silver-white, hard, lustrous, brittle element. It is a member of group VIII of the periodic table. Like iron, it can be magnetized. It is similar to iron and nickel in its physical properties. The element is active chemically, forming many compounds. Cobalt is stable in air and unaffected by water, but is slowly attacked by dilute acids.

Applications

Cobalt is used in many alloys (superalloys for parts in gas turbine aircrafr engines, corrosion resistant alloys, high-speed steels, cemented carbides), in magents and magnetic recording media, as catalysts for the petroleum and chemical industries, as drying agents for paints and inks. Cobalt blue is an important part of artists' palette and is used bu craft workers in porcelain, pottery, stained glass, tiles and enamel jewellery. The radioactive isotopes, cobalt-60, is used in medical treatment and also to irradiate food, in order to preserve the food and protect the consumer.