* Ionic Compounds: Formed by the electrostatic attraction between positively charged ions (cations) and negatively charged ions (anions).

* Ammonium Sulfate (NH₄)₂SO₄:

* Ammonium ion (NH₄⁺): The ammonium ion forms when ammonia (NH₃) gains a proton (H⁺). It has a positive charge.

* Sulfate ion (SO₄²⁻): The sulfate ion forms when sulfur combines with oxygen. It has a negative charge.

Since ammonium sulfate is composed of oppositely charged ions held together by electrostatic forces, it is classified as an ionic compound.