Lewis acid

Definition

A Lewis acid is a chemical species that can accept an electron pair from a donor (Lewis base) to form a coordinate covalent bond. Lewis acids are often electrophilic and can include cations, neutral compounds with vacant orbitals, and molecules with polar bonds.

5 Must Know Facts For Your Next Test

1. Lewis acids do not need to be protons; they can be any electron-pair acceptor.
2. The strength of a Lewis acid depends on its ability to accept electrons, often influenced by its charge and the nature of its substituents.
3. Common examples of Lewis acids include AlCl3, BF3, and H+ ions.
4. A reaction between a Lewis acid and a Lewis base results in the formation of an adduct with a coordinate covalent bond.
5. Lewis acid-base theory broadens the concept of acids and bases beyond proton donors and acceptors.

Review Questions

• What defines a substance as a Lewis acid?
• Name three common examples of Lewis acids.
• What type of bond is formed when a Lewis acid reacts with a Lewis base?

Related terms

Lewis Base:

A chemical species that donates an electron pair to form a coordinate covalent bond with a Lewis acid.

Coordinate Covalent Bond:

A type of covalent bond where both electrons in the bond originate from the same atom, typically formed between a Lewis acid and base.

Electrophile: A molecule or ion that accepts an electron pair during a chemical reaction; essentially synonymous with Lewis acid.