Chapter 13, Problem 79A

(a)

Interpretation Introduction

Interpretation: Type of unit cell in cesium chloride is to be identified.

Concept introduction:

A crystal's internal 3D arrangement of atoms, molecules, or ions is known as its lattice. It consists of many unit cells. A unit cell can be primitive, body-centered, or face-centered.

Answer to Problem 79A

Cubic unit cell

Explanation of Solution

As seen in the image, each edge of the cubic unit cell of the CsCl structure is filled by an anion, and the cell's central "cubic hole" is occupied by a cation.

(b)

Interpretation Introduction

Interpretation: Coordination number of ${\text{Cs}}^{+}$ is to be determined.

Concept introduction:

A crystal's internal 3D arrangement of atoms, molecules, or ions is known as its lattice. It consists of many unit cells. A unit cell can be primitive, body-centered, or face-centered.

Answer to Problem 79A

8

Explanation of Solution

An atom or ion's closest neighbors in a complex, or crystal are determined by the coordination number, which is the total number of atoms, ions, or molecules that a central atom or ion holds. Thus, the coordination number of ${\text{Cs}}^{+}$ in the unit cell is 8.

(c)

Interpretation Introduction

Interpretation: The molecular formula of cesium chloride is to be identified.

Concept introduction:

A crystal's internal 3D arrangement of atoms, molecules, or ions is known as its lattice. It consists of many unit cells. A unit cell can be primitive, body-centered, or face-centered.

Answer to Problem 79A

CsCl

Explanation of Solution

As seen in the image, each edge of the cubic unit cell of the CsCl structure is filled by an anion, and the cell's central "cubic hole" is occupied by a cation. Contribution of atoms on edge is $1/8$ .

There are 8 edges in the unit cell. Chloride ions are present in the edges and one cesium ion is present in the hole. So, there are one chloride ion and one cesium ion per unit cell.

Thus, the molecular formula of cesium chloride is CsCl.