What is the definition of an anion?

An anion is defined as a negatively charged ion. This occurs when an atom or a molecule gains one or more electrons. The addition of these electrons increases the negative charge relative to the number of protons, which are positively charged. As a result, the overall charge of the particle becomes negative, classifying it as an anion.

In contrast, a positively charged ion is known as a cation, which is formed when an atom loses electrons. A neutral atom has an equal number of protons and electrons, resulting in no overall charge. Lastly, an atom with more protons than electrons would also be a cation, as the excess positive charge indicates that it has lost electrons. Understanding these definitions is fundamental in grasping the behavior of ions in chemical reactions and compounds.