Chapter 9, Problem 65A

Interpretation Introduction

Interpretation: The method for writing the formula of ionic compounds containing polyatomic ions is to be explained. The method for writing the name of ionic compounds from their formulas also needs to be stated.

Concept Introduction: Ions containing two or more different types of elements are called polyatomic ions. Sulfate ions, ammonium ions, nitrate ions, etc. are examples of polyatomic ions.

Answer to Problem 65A

The formula of ionic compounds containing polyatomic ions is written by first writing the name and charge of the cation followed by that of the anion. If the magnitude of charges is not the same, the magnitude of charges is interchanged to become the subscript of each other.

Explanation of Solution

In the case of calcium nitrate, it contains ${\text{Ca}}^{\text{2+}}\text{and}{\text{NO}}_{\text{3}}{}^{2-}$ ions. The magnitude of charges is interchanged and written as the subscript ${\text{Ca}}_{\text{1}}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}\to \text{Ca}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}$ . For writing the name of ionic compounds from the formula, the name of the cation is written first followed by the name of the anion.