What is an anion?

An anion is defined as a negatively charged ion. This occurs when an atom or molecule gains one or more electrons, resulting in an excess of negative charge. The gain of electrons increases the number of negative charges relative to the positive charges (which come from protons) in the atom, leading to a net negative charge.

Anions are significant in various chemical processes and play a crucial role in the formation of ionic compounds, where they often pair with cations, which are positively charged ions. This concept is fundamental in understanding chemical bonding and the behavior of elements in reactions.

In contrast to an anion, positively charged ions are known as cations, while ions with no charge would be neutral atoms with an equal number of protons and electrons. An ion formed by adding protons would not make sense in the context of ions, since protons are positively charged and adding them would increase positive charge rather than create an anion.