What is an ion?

An ion is defined as an atom or molecule that has gained or lost one or more electrons, resulting in a net electrical charge. When an atom has the same number of protons and electrons, it is neutral. However, when it loses electrons, it becomes positively charged, known as a cation. Conversely, if it gains electrons, it becomes negatively charged and is referred to as an anion.

This definition aligns with the concept outlined in the chosen answer, highlighting the key feature of ions: the alteration in the electron count compared to protons. Understanding ions is essential in fields such as chemistry and electronics, as they play critical roles in reactions and in the conduction of electricity, particularly in electrolytes and semiconductor materials.