nucleophile

nucleophile, in chemistry, an atom or molecule that in chemical reaction seeks a positive centre, such as the nucleus of an atom, because the nucleophile contains an electron pair available for bonding. Examples of nucleophiles are the halogen anions (I^-, Cl^-, Br^-), the hydroxide ion (OH^-), the cyanide ion (CN^-), ammonia (NH₃), and water. Compare electrophile.