Which element is named from the Latin name for Copenhagen?

Which element is named from the Latin name for Copenhagen? Hafnium is the answer. Its name comes from Hafnia, the Latin name for Copenhagen, where the element was identified in 1922.

Hafnium is element 72, symbol Hf, and a steel-gray transition metal in group 4. Danish physicist Niels Bohr predicted that an element resembling zirconium should exist, but finding it proved difficult because hafnium and zirconium have very similar chemical properties and occur together in minerals.

Dutch physicist Dirk Coster and Hungarian chemist George de Hevesy discovered hafnium in zirconium minerals in Copenhagen. Their identification used X-ray spectroscopy, which revealed the element’s characteristic spectral lines. Hafnium is relatively dense and has a very high melting point of about 2,233 °C.

A common confusion is to associate the name with a person. Unlike rutherfordium or seaborgium, hafnium commemorates a place. Another useful distinction is between hafnium and zirconium: they are chemical neighbours and difficult to separate, but hafnium’s ability to absorb neutrons makes it valuable in nuclear-reactor control rods. Hafnium compounds are also used in high-temperature ceramics and specialized electronics.