Chapter 3, Problem 3H.4BST

(a)

Interpretation Introduction

Interpretation:

Structure type of solid calcium sulfide that is more likely to form has to be determined.

Concept Introduction:

Radius ratio of smaller ion to larger ion in solid state is used to represent relative size of larger ion. This radius ratio is used to predict structure of unit cell from crystal lattice as follows:

$\begin{array}{ccc}\text{Radius ratio}& \text{Crystal structure}& \text{Coordination number}\\ <0.4& \text{zinc-blende structure}& 4\\ 0.4-0.7& \text{rock-salt structure}& 6\\ >0.7& \text{cesium-chloride structure}& 8\end{array}$

Expression to calculate radius ratio $\left(\rho \right)$ is as follows:

  $\rho =\frac{r_{\text{smaller}}}{r_{\text{larger}}}$        (1)

(b)

Interpretation Introduction

Interpretation:

Coordination number for structure type of calcium sulfide has to be determined.

Concept Introduction:

Refer to part (a).