# What is a polyatomic ion?

May 14, 2014

The prefix poly- means many and the prefix mono- means one.

Therefore, polyatomic ions are composed of many atoms.

Examples include: $N {O}_{3}^{- 1}$ and $P {O}_{4}^{- 3}$.

The nitrate ion $N {O}_{3}^{- 1}$ is composed of one nitrogen atoms and three oxygen atoms arranged with an imbalance of one extra electron.

The phosphate ion $P {O}_{4}^{- 3}$ is composed of one phosphate ion and four oxygen atoms arranges with an imbalance of three extra electrons.

Most polyatomic ions are negative with the main exceptions being $N {H}_{4}^{+ 1}$ and ${H}_{3} {O}^{+ 1}$. The ammonium ion which is composed of one nitrogen and 4 hydrogen with an imbalance of one less electron. The hydronium ion is created when water takes on a dissociated ${H}^{+}$ ion in an acid solution.

Monatomic ions are single atoms with a positive or negative charge like Calcium $C {a}^{+ 2}$ having two less electrons and Chloride $C {l}^{- 1}$ having one more electron.