Atomic number:27

Group numbers:9

Period:4

Electronic configuration:[Ar] 3d⁷ 4s²

Formal oxidation number:+2 +3

Electronegativities:1.88

Atomic radius / pm:125.3

Relative atomic mass:58.933195 ± 0.000005

 

Cobalt was discovered by Georg Brandt (DE) in 1739. The origin of the name comes from the German word kobald meaning goblin or evil spirit. It is a hard, ductile, lustrous bluish-grey metal and it's surfaces are stable in air. Cobalt reacts over time with dilute acids and has remarkable magnetic properties. Cobalt occurs in compounds with arsenic and sulfur as in cobaltine (CoAsS) and linneite (Co3S4). Pure cobalt is obtained as a by-product of refining nickel, copper and iron. Cobalt is used in many hard alloys; for magnets, ceramics and special glasses. Radioactive cobalt-60 is used in cancer therapy.

Density / g dm^-3:8900 (293 K)

 7670 (m.p.)

Molar volume / cm³mol^-1:6.62 (293 K)

 7.68 (m.p.)

Electrical resistivity / μΩcm:6.24 (20 °C)

Thermal conductivity / W m^-1K^-1:100

Melting point / °C:1495

Boiling point / °C:2927

Heat of fusion / kJ mol^-1:15.2

Heat of vaporization / kJ mol^-1:382.4

Heat of atomization / kJ mol^-1:423.082

1st ionization energy / kJ mol^-1:760.41

2nd ionization energy / kJ mol^-1:1648.27

3rd ionization energy / kJ mol^-1:3232.28

in the atmosphere / ppm:-

in the Earth's crust / ppm:29

in the oceans / ppm:0.0005