We may use the molecular formula of the compound to determine the number of oxygen atoms in one formula unit. The formula unit is: Mg(NO₃)₂ Here, we can see that there are two nitrate ions in each mole, and each mole of nitrate ion contains three oxygen atoms. Thus, there are 6 oxygen atoms in each formula unit of magnesium nitrate.
The molecular formula indicates the number of atoms of each element in the molecule. Oxygen exists as molecules (diatomic molecules). T<span>he fundamental particles that make up a sample of Oxygen are pairs of atoms, rather than individual atoms. </span><span>You can count the number of atoms of each element in a chemical formula by multiplying the coefficient by the subscript, recognizing that those coefficients and subscripts that are not shown are equal to 1. So, in our case there are 6 atoms of oxygen.</span>
