Final answer:
A polyatomic ion is a group of atoms covalently bonded together with an overall electrical charge. An example of a polyatomic ion is the ammonium ion, which is formed when a hydrogen ion attaches to an ammonia molecule in a coordinate covalent bond.
Step-by-step explanation:
A polyatomic ion is a group of atoms that are covalently bonded together and carry an overall electrical charge.
The ammonium ion (NH4+) is an example of a polyatomic ion. It is formed when a hydrogen ion (H+) attaches to the lone pair of an ammonia (NH3) molecule in a coordinate covalent bond.