Niobium is a grayish white metal with a melting point of 2468℃ and a boiling point of 4742℃ and a density of 8.57 g/cm3.
At room temperature, niobium is stable in the air, and is not completely oxidized in the red heat of oxygen. At high temperature, niobium directly combines with sulfur, nitrogen and carbon, and can form alloys with titanium, zirconium, hafnium and tungsten.
Does not interact with inorganic acids or bases, and is insoluble in aqua regia, but soluble in hydrofluoric acid.The oxidation states of niobium are -1, + 2, +3, +4 and +5.