Main Characterstics or Lewis/Bronsted Definition

Key Questions

  • Both definitions are correct. Neither definition is wrong.

    The definitions are related, but they refer to different phenomena.

    A Brønsted acid is a proton donor. A Brønsted base is a proton acceptor.

    A Lewis acid is an electron pair acceptor. A Lewis base is an electron pair donor.

    If you want to discuss a reaction in terms of proton transfers, you use the Brønsted definitions.

    If you want to discuss a reaction in terms of electron pair transfers, you use the Lewis definitions.

  • A Lewis acid is a molecule that accepts an electron pair, whereas a Lewis base is a molecule that donates an electron pair.

    The implications of this definition are much wider than more traditional definitions.

    For instance,

    Chemistry Libretexts

    ammonia is a Lewis acid and boron trifluoride is a Lewis base in this example.