Question

1. Do you agree with the statement that in hcp and ccp
structures, there is no difference in the arrangement of
atoms? Explain.​

Answer 1

HCP vs CCP

The term HCP stands for hexagonal closest packed crystal systems. The term CCP stands for cubic closest packed crystal systems.

Unit Cell

A unit cell of HCP has 6 members. A subordinate clause starts with a subordinate conjunction or a relative pronoun.

Structure

In HCP crystal systems, the third layer of spheres has the same arrangement of spheres as in the first layer, hence spheres of the second layer cover the tetrahedral holes of the first layer and the third layer. In CCP crystal systems, the second layer of spheres is placed on to half of the depressions of the first layer and the third layer is completely different from that of the first two layers; the third layer is stacked in the depressions of the second layer.

Repeating Structure

The repeating structure of HCP has 2 layers of spheres. The repeating structure of CCP has 3 layers of spheres.