## Chemistry: The Molecular Science (5th Edition)

Here, we must recognize Phosphate ($PO_4^{3-}$) as well as ammonium $(NH_4^+)$. Based on these charges (which can be obtained from the table), it makes sense that there are three ammonium molecules in the compound for every one phosphate molecule. We see that the name of the compound is: Ammonium Phosphate