An ion is an atom or molecule which has lost or gained one or more electrons, making it positively or negatively charged. A negatively charged ion, which has more electrons in its electron shells than it has protons in its nuclei, is known as an anion (; an-eye-on) due to its attraction to anodes. Conversely, a positively-charged ion, which has fewer electrons than protons, is known as a cation (; cat-eye-on) due to its attraction to cathodes.
