In chemistry, azide (/ˈeɪzaɪd/, AY-zyd) is a linear, polyatomic anion with the formula N−3 and structure −N=N+=N−. It is the conjugate base of hydrazoic acid HN3. Organic azides are organic compounds with the formula RN3, containing the azide functional group.[1] The dominant application of azides is as a propellant in air bags.[1]