How are bases defined in relation to hydrogen ions?

Bases are defined as substances that accept hydrogen ions (H⁺) in a chemical reaction. This principle is part of the Brønsted-Lowry theory of acids and bases, which highlights the role of proton transfer. When a base accepts a hydrogen ion, it often leads to the formation of a hydroxide ion (OH⁻) in aqueous solutions, which is characteristic of basic behavior.

In this context, the essential characteristic of a base is its ability to increase the concentration of hydroxide ions in a solution by accepting protons. This acceptance transforms the solution's pH, making it more alkaline. Understanding this definition helps clarify the fundamental interaction between acids and bases in various chemical processes, including physiological responses in the body where maintaining acid-base balance is crucial for metabolic functions.