Chapter 7, Problem 5STP

Interpretation Introduction

Interpretation: To determine if the element loses electrons or gains while forming its ion.

Concept introduction: An ion is formed by losing or gaining one or more electrons which helps them to attain a stable noble gas configuration.

Answer to Problem 5STP

Cesium − loses one electron

Option (D)

Explanation of Solution

An ion is generated by the loss or gain of one or more electrons depending on the configuration of the element.

The number of electrons in the outermost shell, i.e., the valence shell of an element helps to determine if the element needs to lose or gain electrons.

A stable ion is one that has a complete octet or duplet in its outermost shell.

In the case of cesium, the atomic number is $55$ and its electronic configuration is as follows:

  $\text{Cs}\left(55\right):\left[\text{Xe}\right]6s^1$

So, in cesium the electrons in the valence shell is 1, so the element loses this electron to attain stability.