* Identify the elements: The compound contains aluminum (Al), nitrogen (N), and oxygen (O).
* Count the atoms of each element:
* Al: There's one aluminum atom (the subscript is 1, which is understood).
* N: There are three nitrogen atoms (the subscript outside the parentheses is 3).
* O: There are nine oxygen atoms (3 oxygen atoms within the parentheses, multiplied by the 3 subscript outside).
* Total atoms: 1 + 3 + 9 = 13 atoms
Therefore, there are 13 atoms in the compound Al(NO3)3.
