# What are the atoms present in "iron(II) sulfide", "sulfur trioxide", and "magnesium nitrate"?

You tell us! You have $F e S$ (it could be $F {e}_{2} {S}_{3}$ but this is irrelevant to your question), and $S {O}_{3}$, and $M g {\left(N {O}_{3}\right)}_{2} ,$ and ammonia.