Periodic Table


Atomic number: 78
Atomic weight: 195.078
Symbol: Pt
Group number: 10
Electronic configuration: [Xe].4f14.5d9.6s1


Platinum is a beautiful silvery-white metal, when pure, and is malleable and ductile. It has a coefficient of expansion almost equal to that of soda-lime-silica glass, and is therefore used to make sealed electrodes in glass systems.

The metal does not oxidise in air. It is insoluble in hydrochloric and nitric acid, but dissolves when they are mixed as aqua regia, forming chloroplatinic acid (H2PtCl6), an important compound. It is corroded by halogens, cyanides, sulphur and alkalis. Hydrogen and oxygen gas mixtures explode in the presence of platinum wire.

General information

Discoveror: Antonio de Ulloa
Date discovered: 1735
Discovered at: South America
Meaning of name: From the Spanish word "platina" meaning "silver"

Physical data

Standard state: solid at 298 K
Colour: greyish white
Density of solid at ambient temperature/kg m-3: 21090
Molar volume/cm3: 9.09

Radii /pm

Atomic: 177
Covalent (single bond):
Pauling radius for the ion [Pt]-: no data

Valence shell orbital radius maxima (Rmax)
orbital s p d f
radius159.1no data65.920.2


Both values are quoted on the Pauling scale.

Pauling: 2.28
Allred Rochow: 1.44

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: 2041.4
boiling point: 4098

Enthalpies /kJ mol-1

fusion: 19.7
vaporization: 490

single bond enthalpies:
Pt-F Pt-Cl Pt-Br Pt-I Pt-Pt
no data no data no data no data 357.3

Ionization enthalpies /kJ mol-1

Number Enthalpy


This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance
190Pt189.959917 (7)0.01 (1)
192Pt191.961019 (5)0.79 (6)
194Pt193.962655 (4)32.9 (6)
195Pt194.964766 (4)33.8 (6)
196Pt195.964926 (4)25.3 (6)
198Pt197.967869 (4)7.2 (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/Pt.html