Hafnium (Hf)
Hafnium (Hf) is element 72, a transition metal. Atomic mass 178.486, configuration [Xe] 4f¹⁴ 5d² 6s². Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 72 |
|---|---|
| Symbol | Hf |
| Standard atomic weight | 178.486(6) |
| Category | Transition Metal |
| Group | 4 |
| Period | 6 |
| State at room temperature | Solid |
| Electron configuration | [Xe] 4f¹⁴ 5d² 6s² |
| Valence electrons | 2 (Variable) |
| Common oxidation states | +4 |
| Common ions | No common ions |
| Electronegativity (Pauling) | 1.3 |
| First ionization energy | 659 kJ/mol |
| Electron affinity | 1.351 kJ/mol |
| Atomic radius | 155 pm |
| Density | 13.3 g/cm³ |
| Melting point | 2231°C |
| Boiling point | 4603°C |
| Specific heat | 0.144 J/(g·°C) |
Natural isotopes
- Hf-176: Stable
- Hf-177: Stable
- Hf-178: Stable
- Hf-179: Stable
- Hf-180: Stable
Common uses
- Nuclear control rods (absorbs neutrons)
- Plasma cutting tips
- Intel chips (high-k dielectric)
Where it matters
- Nuclear Reactors (Control rods)
- Microprocessors
Hazards
- Fine dust is pyrophoric
History
| Discovered | 1923 |
|---|---|
| Discovered by | Dirk Coster & George de Hevesy |
| Name | From Hafnia (Copenhagen) |