Chemical reactions of the elements
Reaction of tungsten with air
At room temperature, tungsten does not react with air or oxygen, O2. At elevated temperatures (red heat), the trioxide tungsten(VI) oxide, WO3, is formd. Finely divided tungsten metal is pyrophoric.
2W(s) + 3O2(g) → 2WO3(s)
Reaction of tungsten with water
At room temperature, tungsten does not react with water.
Reaction of tungsten with the halogens
Tungsten reacts directly with fluorine, F2, at room temperature to form tungsten(VI) fluoride, WF6. The conditions are much milder than those required for chromium (two places above tungsten in the periodic table).
W(s) + 3F2(g) → WF6(g) [colourless]
Tungsten reacts directly with chlorine, Cl2, at 250°C or bromine, Br2, to form respectively tungsten(VI) chloride, WCl6 or tungsten(VI) bromide, WBr6. Under carefully controlled conditions, tungsten(V) chloride, WCl5, is formed in the reaction between tungsten metal and chlorine, Cl2. It seems that tungsten does react to some extent with iodine, I2, at red heat.
W(s) + 3Cl2(g) → WCl6(s) [dark blue]
W(s) + 3Br2(l) → WBr6(s) [dark blue]
2W(s) + 5Cl2(g) → 2WCl5(s) [dark green]
Reaction of tungsten with acids
Tungsten metal is largely unaffected by most acids.
Reaction of tungsten with bases
Tungsten metal does not react to any significant extent with dilute solutions of hydroxide.