Ion Did you know that an ion is an atom or molecule that has a net electrical charge? This is because the charge of an electron is negative and is equal and opposite to the charge of a proton, which is positive. As a result, the net charge of an ion is not zero since its total number of electrons is different from its total number of protons. Cations are positively charged ions that have fewer electrons than protons, whereas anions are negatively charged ions that have more electrons than protons. Opposite electric charges attract each other by electrostatic force, so cations and anions readily form ionic compounds. Ions can be atomic or monatomic if they consist of only one atom, or molecular or polyatomic if they are made up of two or more atoms. In a fluid, such as gas or liquid, ion pairs are formed by spontaneous molecule collisions, where each generated pair consists of a free electron and a positive ion. Ions can also be created by chemical interactions, such as the dissol...