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1 Allotropes are forms of the same element which exhibit different physical properties. 2  Elements such as carbon, oxygen, phosphorus, tin and sulfur, display allotropy.
Tin is a malleable silvery-white metal which takes a high polish. It possesses a highly crystalline structure and is moderately ductile. When a bar of tin is bent, the crystals break, producing a characteristic 'tin cry'. Two or three allotropic forms of tin exist. Gray or a tin has a cubic structure. Upon warming, at 13.2Â°C gray tin changes to white or b tin, which has a tetragonal structure. This transition from the a to the b form is termed the tin pest. A g form may exist between 161Â°C and the melting point.