Zirconium (Zr): Electron Configuration, Properties and Uses
Zirconium (Zr): Electron Configuration, Properties and Uses
Electron configuration [Kr] 5s2 4d2 · group 4 · period 5 · Ar 91.224
Zirconium data
- Atomic number
- 40
- Relative atomic mass
- 91.224
- Group
- 4
- Period
- 5
- Block
- d
- Category
- Transition metal
- Electron configuration
- [Kr] 5s2 4d2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d2
- Electrons per shell
- 2, 8, 18, 10, 2 (K L M N O)
- Valence electrons
- 4
- Electronegativity (Pauling)
- 1.33
- First ionisation energy
- 6.634 eV
- Atomic radius (van der Waals)
- 186 pm
- State at room temperature
- Solid
- Melting point
- 1855 °C
- Boiling point
- 4409 °C
- Density
- 6.52 g/cm³
- Common oxidation states
- +4
- Discovered
- 1789
Source: PubChem (NIH, accessed 13 Nov 2026); atomic mass: IUPAC standard atomic weight.
Electron shell diagram
K 2 · L 8 · M 18 · N 10 · O 2
Orbital diagram (outer electrons)
About zirconium
With atomic number 40, zirconium (Zr) has 40 protons in its nucleus and 40 electrons as a neutral atom. It is a transition metal in group 4, period 5, d-block. Zirconium was first discovered in 1789. Zirconium is a solid at room temperature, melting at 1855 °C and boiling at 4409 °C.
Zirconium electron configuration
The electron configuration of zirconium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d2, or in short [Kr] 5s2 4d2. Its electrons occupy 5 shells: K = 2, L = 8, M = 18, N = 10, O = 2. For transition metals, valence electrons are counted from the 5s and 4d subshells: 2 + 2 = 4, matching group 4. When it forms cations, electrons leave the outermost subshell first: Zr4+ = [Kr] (like krypton).
Filling order: 1s2(2) → 2s2(4) → 2p6(10) → 3s2(12) → 3p6(18) → 4s2(20) → 3d10(30) → 4p6(36) → 5s2(38) → 4d2(40)
Uses of zirconium
In industry and the laboratory, zirconium turns up in many places, for example nuclear fuel cladding, zirconia ceramics for dental crowns and ceramic knives, and solid-oxide fuel cell electrolytes. For research and analysis you can browse zirconium compounds in the AMI Scientific catalogue.
Safety
Bulk zirconium has low toxicity. The main hazards are its dust and salts, so always check the SDS of the compound you use. Always read the safety data sheet (SDS) before working with a chemical.
Other elements in group 4
Frequently asked questions
What is the electron configuration of zirconium?
The electron configuration of zirconium (Zr, atomic number 40) is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d2, or [Kr] 5s2 4d2 in short. By shell: 2, 8, 18, 10, 2.
How many valence electrons does zirconium have?
Zirconium has 4 valence electrons.
Which group and period is zirconium in?
Zirconium is in group 4, period 5, d-block.
What is the atomic mass of zirconium?
The relative atomic mass of zirconium is 91.224. Use it to calculate molar mass with the molar mass calculator.
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