72 Hf 178.492

Hafnium

TRANSITION METAL

Phase: Solid
Discovered: Dirk Coster
Block: D

Summary

Hafnium 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 zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, making it the penultimate stable element to be discovered (rhenium was identified two years later).

Appearance: steel gray

Source: Wikipedia

Physical Properties

Atomic Mass 178.492 u
Density 13.31 g/cm³
Melting Point 2506 K
Boiling Point 4876 K
Molar Heat 25.73 J/(mol·K)
Electron Affinity 17.18 kJ/mol

Ionization Energies

1st: 658.5 kJ/mol
2nd: 1440 kJ/mol
3rd: 2250 kJ/mol
4th: 3216 kJ/mol