palladium

• Description
• General information
• Physical data
• Radii
• Electronegativities
• Solid state structure
• Temperatures
• Enthalpies
• Ionization Enthalpies
• Isotopes
• Further information

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 (R_max)

orbital	s	p	d	f
radius	no data	no data	58.0	no 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.

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
1st	805
2nd	1875
3rd	3177

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass	Accurate mass	% natural abundance
102Pd	101.905634 (4)	1.02 (1)
104Pd	103.904029 (6)	11.14 (8)
105Pd	104.905079 (6)	22.33 (8)
106Pd	105.903478 (6)	27.33 (3)
108Pd	107.903895 (4)	26.46 (9)
110Pd	109.905167 (20)	11.72 (9)

Further Information

• Additional information about WebElements 1.2.2
• This is a licensed copy (here is the full list) of WebElements 1.2.2 and contains a subset of the material contained within the main version of WebElements (version 2)
• For further information please try WebElements version 2
• Sheffield Chemdex: perhaps the largest internet chemistry directory
• Sheffield Chemputer: interactive chemistry calculators on the WWW