An ion is an atom or molecule carrying an electrical charge because it has an unequal number of protons and electrons. By convention, protons are considered positively charged, and electrons negative and a net electrical charge results whenever there is more of one than the other.
An ion with more protons than electrons carries a net positive charge and is called a cation. Conversely, an anion is a negatively charged ion because it has more electrons than protons.
