Lewis Acid and Bases — Definition & Examples

Lewis Acids and Bases

There two main ways to describe acids/bases known as Bronsted acids/bases and Lewis acids/bases. The difference is whether acids/bases are discussed in terms of protons (Bronsted) or electrons (Lewis).

Lewis acids/bases are described in the ability to accept or donate electrons. Lewis acids accept electrons and Lewis bases donate electrons.

Lewis Acids

Lewis acids (LA) are also known as electrophiles. Electro- means electron and -phile means loving, so electrophile means electron loving. This is why LAs accept electrons. By this definition certain species can be characterized as LAs, such as:

• Cations or positive ions

• Species with a central atom that can have more than 8 electrons.

• Species without a complete quartet

• Species with two atoms with multiple bonds and differing electronegativities

Lewis Bases

Lewis bases (LB) donate electrons. Some examples are:

• Species with a lone pair of electrons

• Anions or negative ions

• Electron rich conjugated sytems

Examples

LAs are in red and LBs are in blue.

(Video) Lewis Acid and Bases

By The Organic Chemistry Tutor

In this video, you will learn that lewis acid is an electron pair acceptor, and lewis base is an electron pair donor. Lewis bases are electron-rich nucleophiles, while lewis acids are electrophiles that are electron poor.

Lewis Acids and Bases: What are lewis acids and bases?