Zirconium (Zr)

Silvery-gray metal

Zirconium is a strong, corrosion-resistant metal that clads nuclear fuel rods and sparkles in cubic form, and with [Kr] 4d² 5s², zirconium has an extremely low thermal neutron absorption cross-section (0.185 barns), making it ideal for nuclear reactors. Cubic zirconia (ZrO₂) is a popular diamond simulant.

Key metrics

Density6.52g/cm³

Melting point2,128K

Boiling point4,650K

Electronegativity1.33Pauling

Discovery

1789discovered

Discovered by: Martin Heinrich Klaproth
Reactivity profile: Highly corrosion resistant
Reactivity: Low
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Kr]}\; \textcolor{#22c55e}{4_{d}^{2}}\; \textcolor{#ef4444}{5_{s}^{2}}

[Kr] 4d2 5s2

Wave function

\Psi_{\text{Zr}} \approx \frac{1}{\sqrt{40!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{40}(\mathbf{r}_{40}) \right|

Probability density $|\Psi|^2$ across the Zr valence shell.

Crystal structure

Hexagonal Close-Packed

Lattice constantsa 1.00 · b 1.00 · c 1.63

Cell anglesα 90° · β 90° · γ 120°

Coordination number12

Atoms per cell2

Atomic packing factor0.74

Physical properties

Atomic radius: 160 pm
Ionization energy: 640 kJ/mol
Electron affinity: 41 kJ/mol
Crystal structure: Hexagonal close-packed (hcp)

Oxidation states

Acid/base

Basic

Strongly acidicStrongly basic

State at 25 °CSolid

2128 K4650 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

468.8nmZr I (blue)Blue100%

477.2nmZr IBlue50%

535.0nmZr I (green)Green60%

Dominant line 468.8 nmRange 469–535 nmTransitions 3