Palladium (Pd)

Silvery-white metal

Palladium is a platinum metal that absorbs 900 times its own volume of hydrogen gas, and with the unique [Kr] 4d¹⁰ configuration (empty 5s shell), palladium can store hydrogen in its interstitial lattice sites. It is used in catalytic converters, fuel cells, and as a catalyst in cross-coupling reactions.

Key metrics

Density12.02g/cm³

Melting point1,828K

Boiling point3,236K

Electronegativity2.2Pauling

Discovery

1803discovered

Discovered by: William Hyde Wollaston
Reactivity profile: Absorbs hydrogen
Reactivity: Low
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Kr]}\; \textcolor{#22c55e}{4_{d}^{10}}

[Kr] 4d10

Wave function

\Psi_{\text{Pd}} \approx \frac{1}{\sqrt{46!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{46}(\mathbf{r}_{46}) \right|

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

Crystal structure

Face-Centered Cubic

Lattice constantsa = 1.00

Cell anglesα = β = γ = 90°

Coordination number12

Atoms per cell4

Atomic packing factor0.74

Physical properties

Atomic radius: 137 pm
Ionization energy: 804 kJ/mol
Electron affinity: 54 kJ/mol
Crystal structure: Face-centered cubic (fcc)

Oxidation states

+2+4

Acid/base

Neutral

Strongly acidicStrongly basic

State at 25 °CSolid

1828 K3236 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

340.5nmPd I (UV)UV70%

363.5nmPd I (UV)UV100%

464.1nmPd I (blue)Blue40%

Dominant line 363.5 nmRange 341–464 nmTransitions 3