An ion is a particle (an atom or molecule etc.) in which the total number of electrons and protons are not the same, giving a net charge unequal to zero. If there are more electrons than protons, the particle will exhibit a negative charge, and if there are less, a positive. An anion is a negatively charged ion, while a cation is positively charged.

Types of Ions[]

An ion is classified into one or multiple groupings depending upon its charge, size and components.

Monatomic Ions[]

A monatomic (or simple) ion is composed of only one atom. Simple ions are most commonly formed when a monatomic element gains or loses one or several electrons. Common monatomic ions are fomed as per

Cl + e-→Cl-

Na→Na+ + e-

Polyatomic Ions[]

A polyatomic ion is composed of two or several elements.


Just like elements, ions have names. They are determined by the elements that the ion is comprised of.

Compounds are comprised of metals and non-metals. The first part of an ion is just the name of the metal element. (I.E NaCl starts with Sodium because the metal element is Sodium.)

Each non-metal has their own prefix, and the prefix is ended with a suffix that is determined by other factors.



  • -ide - by itself (polyatomic ion)
  • -ate - and oxygen