What are polyatomic ions? Give examples.

Explanation

A polyatomic ion is a group of atoms carrying positive or negative charge.
e.g. `{:("Polyatomic ions", "Symbol"),("Ammonium", NH_(4)^(+)),("Hydroxide", OH^(-)),("Nitrate", NO_(3)^(-)):}`
`{:("Hydrogen carbonate", HCO_(3)^(-)),("Sulphate", SO_(4)^(2-)),("Sulphite", SO_(3)^(2-)),("Phosphate", PO_(4)^(3-)),("Carbonate", CO_(3)^(2-)):}`