The formula for mercury(I) chloride is Hg2Cl2. In the formula, the symbol "Hg" stands for mercury and the symbol "Cl" represents chlorine. The numbers in the formula, typically written in subscript, indicate the number of atoms for each element present in a molecule of mercury(I) chloride.
The Roman numeral number in mercury(I) shows the charge of +1 on a mercury ion, for a total charge of +2 on the two ions in Hg2Cl2. That charge is balanced out by the -1 charge on the chloride ion, for a total charge of -2. Balancing the charges gives the molecule a neutral charge. Mercury(I) chloride is a solid with a molar mass of 472.09 grams per mole.