Hafnium (Hf)

From Wikipedia, the free encyclopediaHafnium 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).

Hafnium in the periodic table

SymbolHf
Atomic number72
Group4
Period6
Blockd
Element categoryTransition Metal

Physical properties

Phase at STPSolid
Density13.31 g/cm3
Atomic weight178.492 u
Melting point2506 K
2232.85 °C
4051.13 °F
Boiling point4876 K
4602.85 °C
8317.13 °F

Atomära egenskaper

Electronegativity (Pauling Scale)1.3
Electron affinity17.18 kJ/mol
Ionization energies
1658.5 kJ/mol
2 1440 kJ/mol
3 2250 kJ/mol
4 3216 kJ/mol

Electron configuration

Electron configuration1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d2 6s2
Electrons per shell2, 8, 18, 32, 10, 2

History

Discovered1922
Discovered byDirk Coster
George de Hevesy