Here's how to determine the number of atoms in iron oxide (Fe₂O₃):

* The Formula: Fe₂O₃ tells us there are 2 iron (Fe) atoms and 3 oxygen (O) atoms in each molecule of iron oxide.

* Total Atoms: To find the total number of atoms, add the number of iron and oxygen atoms: 2 + 3 = 5

Therefore, there are 5 atoms in one molecule of iron oxide (Fe₂O₃).