Chapter 7.2, Problem 11SP

Interpretation Introduction

Interpretation: The formula forthe ionic compound formed between calcium cations and chloride anions needs to be determined.

Concept Introduction: Ionic compound is formed by the chemical combination of a metal and a non-metal. Here, metal tends to be electron-rich, and non-metal tends to be electron deficient. Thus, metals donate electron/s to form a positively charged ion or cation and non-metals accept electron/s to form a negatively charged ion or anion. Here, ions of metal and non-metal combine in a fixed ratio to form an ionic compound such that the total charge is zero.

Answer to Problem 11SP

  ${\text{CaCl}}_{\text{2}}$

Explanation of Solution

The given cation and anion are calcium and chloride ions respectively. Here, calcium is metal and belongs to group 2. It has 2 valance electrons which can be donated to form calcium cation or ${\text{Ca}}^{2+}$ . Chlorine is a non-metal and belongs to group 17. It has 7 valance electrons thus; it can gain 1 electron to complete its octet and form a chloride anion ${\text{Cl}}^{-}$ . Since cations and anions combine in a fixed ratio to form an ionic compound such that the total charge is zero thus, 1 ${\text{Ca}}^{2+}$ cation can combine with 2 ${\text{Cl}}^{-}$ anion to form calcium chloride. The formula of ionic compound will be ${\text{CaCl}}_{\text{2}}$ .