5B Explain when parentheses are required when writing a chemical formula for an ionic compound. 5C Can the formula of an ionic compound ever contain TWO sets of parentheses? Explain.

## Step 1In the field of chemistry, parentheses are used in the writing of chemical formulas for ionic compounds to indicate the presence of polyatomic ions. Polyatomic ions are ions that consist of more than one atom. For instance, in the compound ammonium nitrate, the ammonium ion is a polyatomic ion, and the nitrate ion is another. The formula for ammonium nitrate is , where the parentheses around indicate that the nitrate ion is a polyatomic ion.## Step 2However, it is important to note that parentheses are not used when there is only one type of ion present in the compound. For example, in the compound sodium chloride, there is only one type of ion, the sodium ion. Therefore, the formula for sodium chloride is , and parentheses are not used.## Step 3In the case of ionic compounds, it is not possible to have two sets of parentheses. This is because the parentheses are used to indicate the presence of polyatomic ions, and each set of parentheses corresponds to a different polyatomic ion. If there were two sets of parentheses, it would imply that there are two different polyatomic ions in the compound, which is not possible in the context of ionic compounds.