The atoms in a polyatomic ion are joined by covalent bonds.

Here's why:

* Covalent bonds involve the sharing of electrons between atoms. This sharing creates a strong attraction between the atoms, holding them together.

* Polyatomic ions are groups of atoms that carry a net electrical charge. The atoms within these ions are held together by the sharing of electrons, forming covalent bonds.

Example: The sulfate ion (SO₄²⁻) is a polyatomic ion. The sulfur atom and the four oxygen atoms are connected by covalent bonds.

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