A Lewis acid is a species that can accept a pair of electrons from a Lewis base, which is a donator of electrons. In this reaction, AlCl3 is a strong lewis acid and accepts a lone pair of electrons from the Lewis base Cl-, thereby completing Aluminum\'s octet and forming AlCl4-. Solution A Lewis acid is a species that can accept a pair of electrons from a Lewis base, which is a donator of electrons. In this reaction, AlCl3 is a strong lewis acid and accepts a lone pair of electrons from the Lewis base Cl-, thereby completing Aluminum\'s octet and forming AlCl4-..