Here's why:

* Polyatomic ions are groups of atoms covalently bonded together that carry a net positive or negative charge.

* Ionic bonds occur between oppositely charged ions.

Example:

* The polyatomic ion nitrate (NO₃⁻) has a negative charge.

* It can form an ionic bond with a positively charged ion like sodium (Na⁺) to create sodium nitrate (NaNO₃).

Important Note:

While polyatomic ions form ionic bonds within the compound, the atoms within the polyatomic ion itself are held together by covalent bonds.