Platinum , metallic chemical element; symbol Pt; at. no. 78; at. wt. 195.08; m.p. 1,772°C; b.p. 3,827±100°C; sp. gr. 21.45 at 20°C; valence +2 or +4. Pure platinum is a malleable, ductile, lustrous, silver-white metal with a face-centered cubic crystalline structure. Chemically inactive, it is unaffected by common acids but dissolves in aqua regia, forming chloroplatinic acid (H2PtCl6). It is attacked by the hal It does not combine with oxygen even at high temperatures. Like palladium, it absorbs large quantities of hydrogen, which it releases at red heat. Platinum is fo…
