proton acceptor

chemistry

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 13, 2026

Quick Summary

In chemistry, a proton acceptor is defined as a base according to the Brønsted-Lowry theory. This theory, independently proposed by Johannes Nicolaus Brønsted and Thomas Martin Lowry in 1923, states that an acid is a compound that can donate a proton (H⁺), and a base is a compound that can accept a proton.1

When a base accepts a proton, it forms a conjugate acid. Conversely, when an acid donates a proton, it forms a conjugate base. For example, in the reaction between hydrochloric acid (HCl) and ammonia (NH₃), ammonia acts as the base by accepting a proton from HCl, forming the ammonium ion (NH₄⁺), which is the conjugate acid. This theory broadens the definition of acids and bases to include charged species like ions, not just neutral molecules.1

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

2 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

chemical compound
Classification of compounds
…on the other hand, are proton acceptors. The most common base is the hydroxide ion (OH⁻), which reacts with an H⁺ ion to form a water molecule. H⁺ + OH⁻ → HOH (usually written H₂O)
Read More
…on the other hand, are proton acceptors. The most common base is the hydroxide ion (OH⁻), which reacts with an H⁺ ion to form a water molecule. H⁺ + OH⁻ → HOH (usually written H₂O)
Read More

human sensory reception
Sweet
…in the molecule of a proton acceptor, such as the OH (hydroxyl) components of carbohydrates (e.g., sugars) and many other sweet-tasting compounds. It has also been theorized that such molecules will not taste sweet unless they are of appropriate size.
Read More
…in the molecule of a proton acceptor, such as the OH (hydroxyl) components of carbohydrates (e.g., sugars) and many other sweet-tasting compounds. It has also been theorized that such molecules will not taste sweet unless they are of appropriate size.
Read More