Chapter 7, Problem 56A

Interpretation Introduction

Interpretation: To determine the reason for the negative charge on an anion.

Concept Introduction: Anion is a negatively charged ion formed by gaining one or more electrons.

Answer to Problem 56A

Because of the presence of an excess of electrons.

Explanation of Solution

Anion would be the name for an ion that is negatively charged. By gaining one or even more electrons, an atom can produce an anion. For example, chlorine takes one electron to complete its octet. Hence, it is called chlorine anion and as a result, contains one negative charge. It can be expressed as:

  $\text{Cl}+{\text{e}}^{-}\to {\text{Cl}}^{-}$

Atoms are neutral because there is an equal number of protons and electrons. When an electron is added to an atom, the no. of electrons increases which results in a net charge on the ion.