Ammonium sulfate doesn't have a valency in the same way that individual atoms do. Valency refers to the combining power of an atom, which is determined by the number of electrons it can gain, lose, or share to form chemical bonds.

However, we can talk about the charges of the ions that make up ammonium sulfate:

* Ammonium ion (NH₄⁺): Has a +1 charge.

* Sulfate ion (SO₄²⁻): Has a -2 charge.

To form a neutral compound, two ammonium ions (2 x +1 = +2) are needed to balance out the charge of one sulfate ion (-2). This is why the chemical formula for ammonium sulfate is (NH₄)₂SO₄.