Niobium, element symbol: Nb, atomic number 41, is a VB group metal. Its density is 8.57 g/cm3, melting point of 2477 ° C,boiling point of 4744 ° C. Niobium is a silver-gray, soft, and ductile, high-melting point metal.At normal temperature, Niobium doesn't react with air and isn't completely oxidize