Relative atomic mass: 178.49 +- 0.02

English: Hafnium
French: Hafnium
Croatian: Hafnij
German: Hafnium
Italian: Afnio
Spanish: Hafnio

Atomic number: 72
Group numbers: 4
Period: 6
Standard state (20 oC): solid

Discovery: 1923 Dirk Coster (NL), George Charles von Hevesy (HU)
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. The price of 99.9 % pure hafnium pieces is 260.60 for 50 g.
Electronic configuration: [Xe] 4f14 5d2 6s2
Formal oxidation number: +4
Atomic radius: 156.4 pm

Electronegativities: 1.3
Thermal conductivity: 23 W/(m K)
Electrical resistivity (20 oC): 33.08 microOhm cm

Melting point: 2233 oC
Boiling point: 4603 oC

Heat of fusion: 25.5 kJ/mol
Heat of vaporization: 570.7 kJ/mol
Heat of atomization: 618.9 kJ/mol

71Lu <= 72Hf => 73Ta

ASCII Periodic Table of the Elements
6 Jan. 2020
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