WebElements

Periodic Table

palladium

Atomic number: 46
Atomic weight: 106.42
Symbol: Pd
Group number: 10
Electronic configuration: [Kr].4d10

Description

Palladium is a steel-white metal, does not tarnish in air, and is the least dense and lowest melting of the platinum group metals. When annealed, it is soft and ductile. Cold working increases its strength and hardness. It is used in some watch springs.

At room temperatures the metal has the unusual property of absorbing up to 900 times its own volume of hydrogen. Hydrogen readily diffuses through heated palladium and this provides a means of purifying the gas.

General information

Discoveror: William Hyde Wollaston
Date discovered: 1803
Discovered at: England
Meaning of name: Named after the asteroid "Pallas" which was discovered at about the same time and from the Greek name "Pallas", goddess of wisdom

Physical data

Standard state: solid at 298 K
Colour: silvery white metallic
Density of solid at ambient temperature/kg m-3: 12023
Molar volume/cm3: 8.56

Radii /pm

Atomic: 169
Covalent (single bond):
Pauling radius for the ion [Pd]-: no data

Valence shell orbital radius maxima (Rmax)
orbital s p d f
radiusno datano data58.0no data

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: 2.20
Allred Rochow: 1.35

Crystal Structure

structure: ccp (cubic 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.

ball-and-stick.gif

Temperatures (/K)

melting point: 1828.05
boiling point: 3236

Enthalpies /kJ mol-1

fusion: 16.7
vaporization: 377

single bond enthalpies:
Pd-F Pd-Cl Pd-Br Pd-I Pd-Pd
no data no data no data no data 75

Ionization enthalpies /kJ mol-1

Number Enthalpy
1st805
2nd1875
3rd3177

Isotopes

This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance
102Pd101.905634 (4)1.02 (1)
104Pd103.904029 (6)11.14 (8)
105Pd104.905079 (6)22.33 (8)
106Pd105.903478 (6)27.33 (3)
108Pd107.903895 (4)26.46 (9)
110Pd109.905167 (20)11.72 (9)

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/Pd.html