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Zirconium

Element 40 · Transition metal

Specimen

Atomic number
40
Atomic mass
91.222
State at room temperature
Solid
Melting point
1,855 °C
Boiling point
4,409 °C
Density
6.52 g/cm³
Discovered
1789

Atomic mass from IUPAC.1 Other physical data from PubChem.2

Can I eat it?

In food and water
Not needed, little harm known. Zirconium has no known function in the body. The RSC lists it as low in toxicity. There are few studies of zirconium in food. 3

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The atom

Zr
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 10
5 (O) outermost 2
Total40

Configuration [Kr] 4d² 5s²

4d ↑ ↑
5s ↑ ↓
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 40 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Kr core, with one arrow per electron.

Related elements

Group 4
Ti Titanium Hf Hafnium Rf Rutherfordium

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Sources

  1. 1

    IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW), 2024. Abridged Standard Atomic Weights 2024 .

    The atomic mass shown for the 84 elements that have a standard atomic weight.

  2. 2

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  3. 3

    Royal Society of Chemistry, 2026. Zirconium - Element information, properties and uses .

    • Zirconium has no known biological role. It has low toxicity.
  4. 4

    National Institute of Standards and Technology (NIST), 2026. Atomic Weights and Isotopic Compositions for All Elements .

    Isotopic composition of each element; the most abundant isotope sets the neutron count in the nucleus view.