What is a defining feature of a Lewis acid?

A Lewis acid is defined as an electron pair acceptor. This concept comes from the Lewis acid-base theory, which expands the traditional definitions of acids and bases beyond the Bronsted-Lowry definition that focuses on protons. In the Lewis framework, acids are substances that can accept an electron pair from a Lewis base, which is characterized as an electron pair donor.

For instance, when a Lewis acid interacts with a Lewis base, the electron pair from the base is donated to the acid, resulting in the formation of a new bond. This interaction is fundamental in various chemical reactions, including coordination complex formation and electrophilic attacks in organic chemistry.

Understanding this definition is crucial for grasping the broader implications and applications of acid-base theory in chemical reactivity and interactions.