Acids and Bases: Lewis Theory

GOAL(s):

• Recognize molecular properties that allow molecules and ions to act as Lewis acids and bases
• In a neutralization reaction, classify molecules and ions as Lewis acids or bases

The Lewis Theory of Acids and Bases

The Brønsted Theory defines acids and bases as proton donors and acceptors. Around the same time that Johannes N. Brønsted and Thomas M. Lowry came up with their theory of acids and bases, Gilbert N. Lewis proposed his own theory. While the Brønsted-Lowry theory is based on the transfer of protons, Lewis' theory is based on the transfer of electrons.

A Lewis acid is a substance that can accept a pair of electrons to form a new bond. They are sometimes referred to as electrophiles, or seekers of an additional electron pair. A Lewis base is a substance that can donate a pair of electrons to form a new bond. They are sometimes referred to as nucleophiles, or seekers of a positive nucleus. Neutralization is the sharing of an electron pair between an acid and base. The product formed in a neutralization reaction is sometimes called an adduct or complex.