ELEMENTLE

Element 40 · Transition Metal

Zirconium

Period 5 · Group 4

Zirconium is a chemical element with symbol Zr and atomic number 40. The name of zirconium is taken from the name of the mineral zircon, the most important source of zirconium. The word zircon comes from the Persian word zargun زرگون, meaning "gold-colored".

Three reasons Zirconium stands out

  1. 1

    Used in nuclear reactors and very resistant to corrosion and heat.

  2. 2

    Its dioxide is used as an affordable diamond substitute in jewellery, sold as cubic zirconia.

  3. 3

    It is used to make high-performance ceramic knives that hold an edge far longer than steel.

Nuclear transparency in a corrosion-proof metal

Zirconium withstands aggressive chemicals and barely absorbs neutrons, a rare combination that suits nuclear-reactor fuel cladding. The metal must be separated meticulously from hafnium, which occurs beside it but captures neutrons strongly. Cubic zirconia is zirconium dioxide, not metallic zirconium.

Zirconium at a glance
Atomic number / protons40
SymbolZr
Family (Elementle)Transition Metal
Classification (PubChem)Transition metal
Period5
Group4
Atomic mass (u)91.22
Standard stateSolid
Electron configuration[Kr]5s2 4d2
Reported oxidation states+4
Electronegativity (Pauling)1.33
Atomic radius (pm)186
First ionization energy (eV)6.634
Electron affinity (eV)0.426
Density (g/cm³)6.52
Melting point2128 K (1,854.85 °C)
Boiling point4682 K (4,408.85 °C)
Discovery (PubChem)1789

Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.

Sources & further reading

PubChem: Zirconium · Zirconium on Wikipedia

The introduction and original editorial story are adapted from Wikipedia contributors via Periodic-Table-JSON. Element descriptions and their adaptations are available under CC BY-SA 3.0. Numerical attributes use the PubChem periodic-table dataset, retrieved September 22, 2026.