Gallium

CAS Number: 7440-55-3. Gallium is the only metal, except for
mercury, caesium, and rubidium, which can be liquid near room
temperatures, which makes possible its use in high-temperature
thermometers. Ultra-pure gallium has a beautiful, silvery
appearance. Gallium compounds are also used to create
semiconductors and microwave equipment. Chemical formula = Ga.
Molecular weight = 69.72 g/mol.