Question

The total number of octahedral void(s) per atom present in a cubic close packec structure is :-

• A. 2
• B. 4
• C. 1
• D. 3

Answer 1

The Correct Option is C

To determine the number of octahedral voids per atom present in a cubic close-packed (CCP) structure, we need to understand the arrangement of atoms and the concept of voids. In a CCP structure, also known as face-centered cubic (FCC), atoms are tightly packed such that each atom is surrounded by 12 other atoms. This arrangement leaves voids, or empty spaces, between the packed atoms where smaller atoms or ions can fit.

In CCP/FCC structures, there are mainly two types of voids: tetrahedral and octahedral:

• Tetrahedral voids: These are formed between four atoms located at the corners of a tetrahedron. In CCP, there are two tetrahedral voids per one atom.
• Octahedral voids: These are formed between six atoms, situated at the vertices of an octahedron. Each cluster of six atoms leaves an octahedral void.

Now, let’s calculate the number of octahedral voids:

• In a cubic unit cell of a CCP/FCC structure, there are 4 atoms per unit cell.
• The number of octahedral voids per unit cell is equal to the number of atoms in the unit cell.

Therefore, the number of octahedral voids per atom is given by:

\frac{\text{Number of octahedral voids per unit cell}}{\text{Number of atoms per unit cell}} = \frac{4}{4} = 1

Therefore, the total number of octahedral voids per atom present in a cubic close-packed structure is 1.

Hence, the correct answer is 1.