Chapter 3, Problem 3H.7E

(a)

Interpretation Introduction

Interpretation:

Atoms present in unit of bcc structure of iron have to be determined.

Concept Introduction:

Unit cell represents lattice structure if it stacked together repeatedly with no gaps and rotations. This can also produce whole crystals by stacking method. Basic type of unit cells is as follows:

1. Simple cubic (SC).

2. Body centered cubic (BCC).

3. Face centered cubic (FCC).

(b)

Interpretation Introduction

Interpretation:

Coordination number for structure type of iron 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:

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

(c)

Interpretation Introduction

Interpretation:

Length of side of unit cell of iron has to be determined.

Concept Introduction:

Refer to part (a).