072Transition metal · Group 4 · Period 6
Hafnium
Hafnium (Hf) is element 72, a transition metal in the d-block — group 4, period 6. It is a solid at room temperature with 6 electron shells (2, 8, 18, 32, 10, 2) and an atomic mass of 178.492 u.
- Atomic mass
- 178.5 u
- Phase · STP
- solid
- Melting
- 2506 K · 2233 °C
- Boiling
- 4876 K · 4603 °C
- Electronegativity
- 1.3
- Density
- 13.31 g/cm³
Photograph — Hi-Res Images ofChemical Elements, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/hafnium.php
Emission spectrum
The visible light Hafnium emits when energised — its unique spectral fingerprint.
Identity
- Atomic number
- 72
- Standard atomic weight
- 178.5 u
- Category
- Transition metal
- Group
- 4
- Period
- 6
- Block
- d-block
- Oxidation states
- +4
Physical properties
- Melting point
- 2506 K · 2233 °C
- Boiling point
- 4876 K · 4603 °C
- Density
- 13.31 g/cm³
- Molar heat capacity
- 25.73 J/(mol·K)
- Atomic radius
- 212 pm
- Electron affinity
- 17.18 kJ/mol
Atomic structure
72protons
106neutrons
72electrons
2valence e⁻
- Noble-gas notation
- [Xe] 4f14 5d2 6s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d2
- Electrons per shell
- 2, 8, 18, 32, 10, 2
Periodic trends
Where Hafnium ranks across all 118 elements.
Ionization energies
Energy to remove each successive electron (kJ/mol).
658.51
1.4k2
2.3k3
3.2k4
Successive ionization energies (kJ/mol, log scale).
Discovery
- Discovered
- 1923
- Discovered by
- Dirk Coster
- Named by
- —
- Appearance
- steel gray