Transition metals
Hafnium
A heat-resistant metal used in reactor control rods and chips.
Atomic #72Mass178.49Blockd-blockPeriod6Group4
Hf72 · 178.49
3D Atom Explorer
Inside the Hafnium atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Hafnium atom step by step.
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Electron configuration
[Xe] 4f14 5d2 6s2
A neutral Hafnium atom has 72 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Shell 12 e⁻Shell 28 e⁻Shell 318 e⁻Shell 432 e⁻Shell 510 e⁻Shell 62 e⁻
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Properties
Physical & atomic properties
- State (room temp)
- Solid
- Melting point
- 2506 K (2233 °C)
- Boiling point
- 4876 K (4603 °C)
- Density
- 13.31 g/cm³
- Electronegativity
- 1.3 Pauling
- Atomic radius
- 155 pm
- 1st ionization energy
- 659 kJ/mol
- Category
- Transition metals
History
Discovery & naming
- Discovered
- 1923
- Discovered by
- Dirk Coster and George de Hevesy
- Origin of name
- Latin 'Hafnia', for Copenhagen.
Notable uses
Nuclear reactor control rods and superalloys.
Cosmic origin
Where Hafnium comes from
Stellar fusion and dying stars
An important source is slow neutron capture in dying low-mass stars.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 72
- Atomic mass
- 178.49
- Category
- Transition metals
- Group · Period
- 4 · 6
- Block
- d-block
- Shells
- 2 · 8 · 18 · 32 · 10 · 2