ElementsWhat is zirconium?
Zirconium is a grey-white metal that resists heat and corrosion very well. Its oxide is used to make cubic zirconia, a popular diamond look-alike.
What is zirconium used for?
Cladding for fuel rods in nuclear reactors, tough ceramics for knives and dental crowns, and gemstones.
Where the name comes from
From zircon, a gemstone that contains it.
Key facts
- Symbol
- Zr
- Atomic number
- 40
- Atomic mass
- 91.22 u
- Family
- Transition metal
- Period
- 5
- Group
- 4
- Block
- d
- State at room temperature
- Solid
- Melting point
- 1,855 °C (2,128 K, 3,371 °F)
- Boiling point
- 4,409 °C (4,682 K, 7,968 °F)
- Density
- 6.52 g/cm³
- Electrons per shell
- 2, 8, 18, 10, 2
- Electron configuration
- [Kr]5s2 4d2
- Common oxidation states
- +4
- Electronegativity (Pauling)
- 1.33
- First ionisation energy
- 6.634 eV
- Electron affinity
- 0.426 eV
- Atomic radius (van der Waals)
- 186 pm
- Discovered
- 1789
Place in the periodic table
Zirconium is element number 40. It sits in period 5 (row 5) of the periodic table, in group 4 (column 4), and belongs to the d-block. Just before it comes yttrium (39), and just after it comes niobium (41). In the same column, titanium is above it and hafnium is below it. Elements in one column tend to behave alike.
Family: Transition metals.
Physical properties
At room temperature zirconium is a solid. It melts at 1,855 °C and boils at 4,409 °C, so it stays liquid over a range of 2,554 degrees. Its density is 6.52 grams per cubic centimetre, so a one-litre block would weigh about 6.52 kilograms. By density it ranks 55th among the 96 elements with a measured value.
Inside the atom
An atom of zirconium has 40 protons in its nucleus and, when neutral, 40 electrons around it. The electrons are arranged in 5 shells: 2, 8, 18, 10, 2. The outermost shell holds 2 electrons. Written in full, the electron configuration is [Kr]5s2 4d2.
Its electronegativity on the Pauling scale is 1.33. 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 6.634 electronvolts (about 640 kilojoules per mole). One mole of zirconium weighs 91.22 grams, so a single gram contains about 6.60 × 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 zirconium 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.