The density of tungsten hexafluoride is about 13g per liter, which is about 1 1 times that of air, so it is the densest gas. Tungsten hexafluoride is an inorganic compound formed by fluorine and tungsten, and its chemical formula is WF6. Tungsten hexafluoride is a colorless, toxic and corrosive gas, and chemical vapor deposition of WF6 is used to form tungsten films in semiconductor device manufacturing industry.