Explanation:
The chemical formula magnesium sulfide written as MgS and NOT [tex]Mg_{2}S_{2}[/tex] because charge on magnesium ion is +2 and charge on sulfide ion is -2.
Therefore, these charges will cancel out each other as we write the formula in simplest crisscross method.
Also, the numbers in a chemical formula display the total number of atoms attached with each other or central atom.
For example, in [tex]CaCl_{2}[/tex] there are two chlorine atoms attached to one calcium atom.
Therefore, [tex]MgS[/tex] denotes one sulfur atom is attached to magnesium atom. Hence, we do not write the formula of magnesium sulfide as [tex]Mg_{2}S_{2}[/tex] because this shows two magnesium atoms are attached to two sulfur atoms which is not true.
