An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The word ion is the transliteration of the Greek participle ἰόν (meaning “going”), and was first used by physicist Michael Faraday for the substances that allow a current to pass (“go”) between electrodes in a solution, when an electric field is applied.
An ion consisting of a single atom is an atomic or monatomic ion; if it consists of two or more atoms, it is a molecular or polyatomic ion.
Since the electric charge on a proton is equal in magnitude to the charge on an electron, the net electric charge on an ion is equal to the number of protons in the ion minus the number of electrons.
An anion (−) ( /ˈæn.aɪ.ən/ AN-eye-ən), from the Greek word ἄνω (ánō), meaning “up”, is an ion with more electrons than protons, giving it a net negative charge (since electrons are negatively charged and protons are positively charged…