ElementsWhat is hafnium?
Hafnium is a shiny, silvery metal that is always found with zirconium and is hard to separate from it.
What is hafnium used for?
Control rods in nuclear reactors, heat-resistant alloys for rocket nozzles, and insulating layers in computer chips.
Where the name comes from
From Hafnia, the Latin name for Copenhagen, where it was discovered.
Key facts
- Symbol
- Hf
- Atomic number
- 72
- Atomic mass
- 178.49 u
- Family
- Transition metal
- Period
- 6
- Group
- 4
- Block
- d
- State at room temperature
- Solid
- Melting point
- 2,233 °C (2,506 K, 4,051 °F)
- Boiling point
- 4,603 °C (4,876 K, 8,317 °F)
- Density
- 13.3 g/cm³
- Electrons per shell
- 2, 8, 18, 32, 10, 2
- Electron configuration
- [Xe]6s2 4f14 5d2
- Common oxidation states
- +4
- Electronegativity (Pauling)
- 1.3
- First ionisation energy
- 6.825 eV
- Electron affinity
- no value
- Atomic radius (van der Waals)
- 212 pm
- Discovered
- 1923
Place in the periodic table
Hafnium is element number 72. It sits in period 6 (row 6) of the periodic table, in group 4 (column 4), and belongs to the d-block. Just before it comes lutetium (71), and just after it comes tantalum (73). In the same column, zirconium is above it and rutherfordium is below it. Elements in one column tend to behave alike.
Family: Transition metals.
Physical properties
At room temperature hafnium is a solid. It melts at 2,233 °C and boils at 4,603 °C, so it stays liquid over a range of 2,370 degrees. Its density is 13.3 grams per cubic centimetre, so a one-litre block would weigh about 13.3 kilograms. By density it ranks 16th among the 96 elements with a measured value. It has the 10th highest melting point of all elements.
Inside the atom
An atom of hafnium has 72 protons in its nucleus and, when neutral, 72 electrons around it. The electrons are arranged in 6 shells: 2, 8, 18, 32, 10, 2. The outermost shell holds 2 electrons. Written in full, the electron configuration is [Xe]6s2 4f14 5d2.
Its electronegativity on the Pauling scale is 1.3. This number shows how strongly an atom pulls shared electrons towards itself: fluorine, the strongest, is 3.98. Removing one electron from an atom takes 6.825 electronvolts (about 659 kilojoules per mole). One mole of hafnium weighs 178.49 grams, so a single gram contains about 3.37 × 1021 atoms.
The ring picture is a simple model that only counts the electrons in each shell. Real atoms do not look like this.
Next steps
- Work out the weight of a compound that contains hafnium with the molar mass calculator.
- Compare it with every other element in the sortable list.
- Test yourself with the symbol quiz.
Figures on this page are from PubChem (U.S. National Library of Medicine), as downloaded on 11 November 2026. See About and data sources.