Atomic number:72

Group numbers:4

Period:6

Electronic configuration:[Xe] 4f¹⁴ 5d² 6s²

Formal oxidation number:+4

Electronegativities:1.3

Atomic radius / pm:156.4

Relative atomic mass:178.49 ± 0.02

 

Hafnium was discovered by Dirk Coster (NL) and George Charles von Hevesy (HU) in 1923. The origin of the name comes from the Latin name Hafnia meaning Copenhagen. It is a silvery, ductile, toxic metal that resists alkalis and acids (except HF). Metal ignites and burns readily and the exposed surfaces form oxide film. Hafnium is obtained from mineral zircon or baddeleyite. It is used in reactor control rods because of its ability to absorb neutrons.

Density / g dm^-3:13310 (293 K)

 12000 (m.p.)

Molar volume / cm³mol^-1:13.41 (293 K)

 14.87 (m.p.)

Electrical resistivity / μΩcm:33.08 (20 °C)

Thermal conductivity / W m^-1K^-1:23

Melting point / °C:2233

Boiling point / °C:4603

Heat of fusion / kJ mol^-1:25.5

Heat of vaporization / kJ mol^-1:570.7

Heat of atomization / kJ mol^-1:618.9

1st ionization energy / kJ mol^-1:658.52

2nd ionization energy / kJ mol^-1:1437.64

3rd ionization energy / kJ mol^-1:2248.12

in the atmosphere / ppm:-

in the Earth's crust / ppm:3

in the oceans / ppm:0.008