Platinum (Pt)

Stable isotopes of platinum available from ISOFLEX

Isotope Z(p) N(n) Atomic Mass Natural Abundance Enrichment Level Chemical Form
Pt-190  78  112  189.95993 0.014%  4.00% Metal
Pt-192  78  114  191.961035 0.782%  56.00% Metal
Pt-194  78  116  193.962663 32.967%  >96.00% Metal
Pt-195  78  117  194.964774 33.832%  >96.00% Metal
Pt-196  78  118  195.964934 25.242%  >97.00% Metal
Pt-198  78  120  197.967875 7.163%  >91.00% Metal

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Platinum was discovered in 1735 by Antonio de Ulloa. Its name derives from the Spanish word platina, meaning “silver.”

Platinum is a silvery white, ductile, lustrous metal with face-centered cubic crystals. When heated, platinum absorbs large volumes of hydrogen. It is also a strong complexing agent. It has a vapor pressure of 0.00014 torr at its melting point. It has a magnetic susceptibility of 9.0 x 10-6 cm3/g. As a catalyst it is abnormally sensitive to poisons. It is insoluble in mineral and organic acids, and soluble in aqua regia. It is attacked by fused alkalis. It does not corrode or tarnish. At ordinary temperatures platinum is inert to practically all substances except aqua regia and, to a small extent, chlorine water. It reacts with oxygen only at elevated temperatures. Finely divided metal forms platinum oxide at about 500 ºC. Fused alkalis, particularly potassium and barium hydroxides, are corrosive to platinum. Platinum can be alloyed with many elements at elevated temperatures.

Platinum metal and its alloys have numerous applications. It is used extensively as a precious metal in the manufacture of jewelry. Other important applications include construction of laboratory crucibles and high-temperature electric furnaces, in instruments as thermocouple elements, as wire for electrical contacts, as electrodes, in dentistry, in cigarette lighters, and for coating missile and jet engine parts. Platinum is also used extensively as a catalyst in hydrogenation, dehydrogenation, oxidation, isomerization, carbonylation and hydrocracking. It is also used in organic synthesis and petroleum refining. An important application is in the catalytic oxidation of ammonia in Ostwald’s process in the manufacture of nitric acid. Platinum is installed in the catalytic converters in automobile engines for pollution control.

Properties of Platinum

Name Platinum 
Symbol Pt 
Atomic number 78 
Atomic weight 195.09 
Standard state Solid at 298 ºK
CAS Registry ID 7440-06-4 
Group in periodic table 10 
Group name Precious metal or platinum group metal 
Period in periodic table
Block in periodic table d-block 
Color Grayish white 
Classification Metallic 
Melting point 1768.4 °C
Boiling point 3827 °C
Vaporization point 3825 ºC
Thermal conductivity 71.6 W/(m·K) at 298.2 ºK
Electrical resistivity 10.6 µΩ·cm at 20 ºC 
Electronegativity 2.2 
Specific heat 0.13 kJ/kg K 
Heat of vaporization 490 kJ·mol-1
Heat of fusion 20 kJ·mol-1
Density of liquid 19.77 g/cm
Density of solid 21.5 g/cm
Electron configuration [Xe]4f145d96s1 
Atomic radius 1.39 Å 
Ionic radii Pt2+: 0.60 Å and Pt4+: 0.63 Å
(coordination numbers 4 and 6)
Oxidation states  +2, +3, +4 
Most common oxidation state  +4