Periodic Table


Atomic number: 40
Atomic weight: 91.224
Symbol: Zr
Group number: 4
Electronic configuration: [Kr].4d2.5s2


Zirconium is found in abundance in S-type stars, and has been identified in the sun and meteorites. Analyses of lunar rock samples show a surprisingly high zirconium oxide content, compared with terrestrial rocks. Some forms of zircon have excellent gemstone qualities.

Zirconium is a grayish-white lustrous metal. The finely divided metal may ignite spontaneously in air, especially at elevated temperatures. The solid metal is much more difficult to ignite. The inherent toxicity of zirconium compounds is low. Hafnium is invariably found in zirconium ores, and the separation is difficult. Commercial grade zirconium contains from 1 to 3% hafnium.

General information

Discoveror: Martin Heinrich Klaproth
Date discovered: 1789
Discovered at: Berlin, Germany
Meaning of name: From the Arabic word "zargun" meaning "gold colour"

Physical data

Standard state: solid at 298 K
Colour: silvery white
Density of solid at ambient temperature/kg m-3: 6511
Molar volume/cm3: 14.02

Radii /pm

Atomic: 206
Covalent (single bond):
Pauling radius for the ion [Zr]-: no data

Valence shell orbital radius maxima (Rmax)
orbital s p d f
radius178.5no data84.0no data


Both values are quoted on the Pauling scale.

Pauling: 1.33
Allred Rochow: 1.22

Crystal Structure

structure: hcp (hexagonal close-packed)

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.


Temperatures (/K)

melting point: 2128
boiling point: 4682

Enthalpies /kJ mol-1

fusion: 21.0
vaporization: 581

single bond enthalpies:
Zr-F Zr-Cl Zr-Br Zr-I Zr-Zr
no data no data no data no data no data

Ionization enthalpies /kJ mol-1

Number Enthalpy


This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance
90Zr89.9047026 (26)51.45 (3)
91Zr90.9056439 (26)11.22 (4)
92Zr91.9050386 (26)17.15 (2)
94Zr93.9063148 (28)17.38 (4)
96Zr95.908275 (4)2.80 (2)

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Zr.html