#72 HafniumHafnium is a chemical element with symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Atomic mass:178.49 amu Melting point:2150.0 °C (2423.15 K, 3902.0 °F) Boiling point:5400.0 °C (5673.15 K, 9752.0 °F) Density:293 K:13.2 g/cm3 |