Hafnium is named after Hafnia, the Latin word for the city of Copenhagen in Denmark. It took a long time to distinguish hafnium from zirconium because the two elements are present together in crystals of the mineral zircon and their atoms are of similar sizes. Hafnium is used in powerful cutters that pierce metal objects with a hot stream of sparks. It is also used to manufacture ultra-small electronic products, only a few millionths of a millimeter wide, in microchips.

Summary of properties (Hf)

Atomic weight178.486(6)
Discoverer (year)Coster, Dirk & De Hevesy, George Charles (1923)
Natural formmetallic solid (hexagonal)
Electron configuration[Xe] 414 5d2 6s2
Melting point (ºC)2150
Boiling point (ºC)5400
Abundance in earth's crust (ppm)3
Isotope (abundance)174Hf (0.16), 176Hf (5.26), 177Hf (18.60), 178Hf (27.28), 179Hf (13.62), 180Hf (35.08)
Density g/cm313.31
Van der Waals radius (pm)223
Covalent radius (pm)164
Electronegativity (Pauling)1.3
Vaporization enthalpy (kJ/mol)661.10
Enthalpy of fusion (kJ/mol)27.20
Specific heat capacity (J/g·K) at 25ºC and 1 atm0.14
Thermal conductivity (W/cm·K) at 25ºC and 1 atm0.230
Oxidation state+4
Electron affinity (eV)0.01
1st Ionization potential (eV)6.8251

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