A Level Biology Practice Exam 2026 - Free A Level Biology Practice Questions and Study Guide

An anion is a negatively charged ion that has gained one or more electrons, resulting in a surplus of electrons compared to protons. This means that anions are characterized by their ability to accept electrons, making them essential in various chemical reactions, especially in ionic bonding.

On the other hand, a cation is a positively charged ion that has lost one or more electrons, resulting in a deficit of electrons relative to protons. This loss of electrons results in a positive charge, thus making cations crucial for the formation of compounds and the conduction of electricity in solutions.

Understanding the distinction between anions and cations is fundamental in chemistry as it helps to explain many processes, such as electrical conductivity in solutions, the stability of ionic compounds, and the behavior of ions in biological systems.