No, NH4^- (ammonium ion) is not a metal. It is an ion formed by the reaction of ammonia (NH3) with a hydrogen ion (H+). The ammonium ion consists of four hydrogen atoms bonded to a central nitrogen atom, giving it the chemical formula NH4^-. It is a polyatomic ion and does not exhibit typical metallic properties. Metals are elements that generally have high electrical and thermal conductivity, luster, and malleability, which are not characteristics of the ammonium ion.