Hafnium
Hafnium is a chemical element with symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, making it the penultimate stable element to be discovered (rhenium was identified two years later).
A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.
54 is the [Xe] core total across five shells.
At a glance
- Atomic number
- 72
- Atomic mass
- 178.492 u
- Phase
- Solid
- Density
- 13.31 g/cm³
- Melting point
- 2,506 K
- Boiling point
- 4,876 K
- First ionization energy
- 658.5 kJ/mol
- Electronegativity
- 1.3
- Electron affinity
- 17.18 kJ/mol
- Molar heat capacity
- 25.73 J/(mol·K)
- Period
- 6
- Appearance
- steel gray
Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.
Keep exploring
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