Comparing the Arrhenius and the Brønsted–Lowry Definitions of Acids and Bases

• The Arrhenius definition of acids and bases cannot explain why some substances act as bases even though they do not contain OH−.
• The Arrhenius definition does not apply to nonaqueous solvents.
• The Brønsted–Lowry definition of acids and bases applies to a wider range of acid–base phenomena.
• This definition focuses on the transfer of H+ ions in an acid–base reaction.
• Since an H+ ion is a proton—a hydrogen atom with its electron taken away—this definition focuses on the idea of a proton donor and a proton acceptor.