Quick Facts
| Property | Value |
|---|---|
| Symbol | Hf |
| Atomic Number | 72 |
| Atomic Mass | 178.49 u |
| Category | Transition Metal |
| Period | 6 |
| Group | 4 |
| Block | d |
| Electron Configuration | [Xe] 4f¹⁴ 5d² 6s² |
Physical Properties
| Property | Value |
|---|---|
| State at 20°C | Solid |
| Density | 13.31 g/cm³ |
| Melting Point | 2233°C (2506 K) |
| Boiling Point | 4603°C (4876 K) |
| Appearance | Lustrous, silvery-gray metal |
History and Discovery
Discovered by: Dirk Coster and George de Hevesy Year of Discovery: 1923 Location: Copenhagen, Denmark
Etymology
Named after Hafnia, the Latin name for Copenhagen.
Applications and Uses
- Nuclear reactor control rods (high neutron absorption)
- Superalloys for jet engines
- Plasma cutting tips
- High-k dielectric in microprocessors (HfO₂)
- Incandescent filaments
Interesting Facts
- Almost always found with zirconium (difficult to separate)
- Hafnium is good at absorbing neutrons; zirconium is transparent to them
- Used in Intel processors since 2007
- Named after the city where it was discovered
- Predicted by Mendeleev and confirmed by X-ray spectroscopy