Chapter 7, Problem 39A

Interpretation Introduction

Interpretation: The reason for ionic compounds to be electrically neural needs to be explained.

Concept Introduction: An ionic compound is formed when a metal reacts with a non-metal. Here, metal is electron-rich and loses electrons while non-metal is electron deficient, thus, it gains electrons. In an ionic compound, metal hasa positive charge and non-metal hasa negative charge.

Answer to Problem 39A

Metal and non-metal always combine in the ratio so that the total charge of the compound is zero.

Explanation of Solution

In an ionic compound, metal and non-metal combine chemically. Here, the metal loses electrons and non-metal gains electrons. The charge on the metal and non-metal depends on the number of electrons lose and gain respectively. Here, metal and non-metals are combined in a ratio such that the total charge is zero. For example, if metal M has a +2 charge and non-metal X has a -1 charge, both M and X combine in the ratio of 2:1 and form ${\text{M}}_{\text{2}}\text{X}$ compound. Here, 2 ${\text{M}}^{+}$ and 1 ${\text{X}}^{2-}$ ions are combined.

Since metal and non-metal always combine in the ratio, the total charge of the compound is zero. Thus, the ionic compound is always electrically neutral.