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 losses electrons, it becomes positively charged and is referred to as a cation. Conversely, when it gains electrons, it carries a negative charge and is known as an anion. This change in the number of electrons affects the atom's overall charge but does not alter its identity as that particular element, as the number of protons remains constant.

The understanding of ions is crucial in the context of chemical reactions, electrical conductivity in solutions, and biological processes. For instance, many biological functions depend on ions, such as nerve impulse transmission and muscle contraction, which highlights their significance beyond just chemistry.

In contrast, the other options do not accurately represent the concept of an ion. A neutral atom is one that has an equal number of protons and electrons, meaning it does not possess a charge. A stable molecular structure generally refers to molecules that are in a low-energy state, which can include both charged and uncharged species. Lastly, a molecule with no electrical charge could be a neutral molecule but does not convey the definition of an ion, since ions, by definition, must have a charge. Thus,