Question

ABABAB layering pattern is called hexagonal close packing, found in HCP lattice. If the statement is true enter 1, else enter 0.

Answer 1

Hint: Atoms are space filling entities and structures that can be described as resulting from the packing of spheres. The most efficient, called closest packing can be achieved in two ways, one of which is HCP and the other is CCP ( cubic close packing).

Complete step by step solution:
Let us now understand how hexagonal close packing takes place, it is built up as follows: place a sphere on a flat surface.
Surrounded with six equal spheres as close as possible in the same plane. Looking down on the plane. The projection is as shown in the figure given below. Let's call this layer as A layer. Now form over the first layer a second layer of equally bunched spheres such that it nestles into the voids that is the empty space. It will be clearly seen that once the sphere is placed on the void, it blocks the voids which are adjacent to that void.

Let us call this layer the B layer. Now, it can be clearly seen that there are two types of voids created by the B layer of spheres. If a sphere is placed on the X type of the voids, it would resemble the A layer of spheres in the sense that it would eclipse the spheres of the A layer. This arrangement ABAB is known as hexagonal close packing (HCP).

Hence we can conclude that the above statement is true and therefore we will enter 1.

Note:
One of the main properties for solid is that the molecules or atoms are tightly packed therefore the most efficient packing must be the one with least or no spaces between the atoms. Hexagonal close packing or hexagonal primitive is one of them.