Hafnium

Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869. Hafnium was the penultimate stable isotope element to be discovered (rhenium was identified two years later). Hafnium is named after Hafnia, the Latin name for "Copenhagen", where it was discovered.
Symbol: Hf
Electron configuration: Xe 4f14 5d2 6s2
Melting point: 2,231 °C
Discovered: 1923
Atomic number: 72
Atomic mass: 178.49 ± 0.02 u
Discoverers: George de Hevesy, Dirk Coster