Question

Number of octahedral void(s) per atom present in a cubic close packed structure is :
A. $1$
B. $2$
C. $4$
D. $6$

Answer 1

Firstly we should be clear that what exactly is the ccp structure and what it represents along with that. So we get that it is a specific way of lattice integration in which we have the atoms arranged accordingly creating voids. We know that, octahedral void is surrounded by six spheres and the number of tetrahedral voids is equal to the number of closed packed particles in the lattice.

Complete step-by-step answer: Firstly we should be aware of the concept of the mole which is known as mole concept.We know that in any type of close packing two types of void are formed,
1. Tetrahedral void
2. Octahedral void
In geometry, close-packing of equal spheres is a dense arrangement of congruent spheres in an infinite, regular arrangement (or lattice). Carl Friedrich Gauss proved that the highest average density – that is, the greatest fraction of space occupied by spheres – that can be achieved by a lattice packing is: $0.7408$ .As we know, in any type of close packing, one octahedral void is attached with one atom. In cubic close packing, there is $1$ atom and so, it has one octahedral void.

Therefore the correct option is option A, $1$ .

Note: Many crystal structures are based on a close-packing of a single kind of atom, or a close-packing of large ions with smaller ions filling the spaces between them. The cubic and hexagonal arrangements are very close to one another in energy, and it may be difficult to predict which form will be preferred from first principles.