Appearance and Characteristics
Harmful effects:
Tin is considered to be non-toxic but most tin salts are toxic. The inorganic salts are caustic but of low toxicity. Organometallic compounds of tin are highly toxic.
Characteristics:
Tin is a silvery-white, soft, malleable metal that can be highly polished. Tin has a highly crystalline structure and when a tin bar is bent, a ‘tin cry’ is heard, due to the breaking of these crystals. It resists oxygen and water but dissolves in acids and bases. Exposed surfaces form an oxide film. When heated in air, tin forms tin(IV) oxide (stannic oxide) which is feebly acidic.
Tin has two allotropic forms at normal pressure, gray tin and white tin. Pure white tin slowly tends to become the gray powder (gray tin), a change commonly called ‘tin pest’ at temperatures below 13.2 oC. Gray tin has no metallic properties at all. Commercial quality tins are resistant to tin pest as a result of the inhibiting effects of minor impurities.