Atomic number 72
Hafnium
Transition metal
In the real world
Quick facts
- Atomic mass
- 178.49
- Group
- 4
- Period
- 6
- State (STP)
- solid
- Electronegativity
- 1.30
- Common ox. states
- +4
Properties
Electron configuration
[Xe] 4f¹⁴ 5d² 6s²
- Ionization energy
- 658.5 kJ/mol
- Electron affinity
- 17.2 kJ/mol
- Melting point
- 2506.00 K (2232.8 °C)
- Boiling point
- 4876.00 K (4602.9 °C)
How dangerous is it?
1/5 · Low risk
As a solid metal it is safe to handle and does little to you. The only real concern is the fine powder, which can catch fire on its own in air.
- FlammableImmediate
Finely divided hafnium powder is pyrophoric, meaning it can ignite in air without a spark. (only the fine powder is a fire risk, not the bulk metal)
The powder is kept under inert gas or liquid; solid pieces need no special care.
How it bonds
Hafnium parallels zirconium (same group, almost identical chemistry - they are notoriously hard to separate). Dominant +4 state. Excellent neutron absorber, so used in nuclear-reactor control rods (the opposite job from zirconium).
