Element 72
Hafnium (Hf)
Hafnium (Hf) is element 72 of the periodic table, a transition metal in period 6, group 4 (d-block) with an atomic mass of 178.49 and is a solid at standard conditions.
At a glance
- Atomic number
- 72
- Symbol
- Hf
- Atomic mass
- 178.49 u
- Category
- Transition metals
- Period
- 6
- Group
- 4
- Block
- d-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d2 6s2
- Shorthand configuration
- [Xe] 4f14 5d2 6s2
- Electrons per shell
- 2, 8, 18, 32, 10, 2
- Oxidation states
- -2, +1, +2, +3, +4
Physical properties
- Melting point
- 2506 K
- Boiling point
- 4876 K
- Density
- 13.31 g/cm3
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 1.3
- Atomic radius
- 208 pm
- Covalent radius
- 175 pm
- First ionization energy
- 659 kJ/mol
- Electron affinity
- 0 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Hf-180 | 179.94656 | 35.08% | Stable |
Common uses
- Nuclear reactor control rods
- Superalloys
- Plasma cutting
- Microprocessors
Discovery
- Year
- 1923
- Discovered by
- Dirk Coster, George de Hevesy
- Country
- Denmark