Beginning Organic Chemistry (BOC)
1. Basic Knowledge
f. Acids and Bases
1. Theories of Acid/Base Behaviour

Return to BOC Index. | 2. Acid-Base Equilibria

1. Arrhenius:

Acids ionize to produce hydrogen ions; bases ionize to produce hydroxide ions.

2. Brønsted and Lowry:

An acid donates a proton to a base; a base accepts a proton from an acid.

This definition of a so-called "proton" acid is often used in organic chemistry.

3. Lewis:

An acid accepts an electron pair from a base to form a covalent bond; a base donates an electron pair to an acid to form a covalent bond.

This is the widest of definitions of the acid/base concept and is also of use in organic chemistry.
The Brønsted and Lowry concept is essentially the same as the Lewis concept with "acids" limited to protons.

A set of overheads reviewing acid base concepts is available:

Introduction to acid/base equilibria and pH
Structure and acid strength: electronic effects.

Date created: 2005 06 07.