Description

 
Platinum is a lustrous silvery-white, malleable, ductile metal and a member of group 10 of the periodic table of the elements. It has the third highest density, behind osmium and iridium. Platinum is unaffected by air and water, but will dissolve in hot aqua regia, in hot concentrated phosphoric and sulphuric acids, and in molten alkali. It is as resistant as gold to corrosion and tarnishing. Indeed, platinum will not oxidize in air no matter how strongly it is heated.
 
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. Hydrogen and oxygen gas mixtures explode in the presence of platinum wire.