Name: platinum
Symbol: Pt
Atomic number: 78
Atomic weight: 195.078 (2)
Group in periodic table: 10
Group name: Precious metal
Period in periodic table: 6
Block in periodic table: d-block
CAS registry ID: 7440-06-4
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.