Here's how to break down the number of atoms in the compound ammonium phosphate (NH₄₃PO₄):

* Identify the elements: The compound contains nitrogen (N), hydrogen (H), phosphorus (P), and oxygen (O).

* Count the atoms of each element:

* Nitrogen (N): There is 1 nitrogen atom.

* Hydrogen (H): There are 12 hydrogen atoms (3 groups of 4).

* Phosphorus (P): There is 1 phosphorus atom.

* Oxygen (O): There are 4 oxygen atoms.

* Total atoms: 1 + 12 + 1 + 4 = 18 atoms

Therefore, there are 18 atoms in a molecule of ammonium phosphate (NH₄₃PO₄).