Question

The formula of crystalline solid having atoms 'B' in
ccp arrangement, atoms 'A' occupying half of
octahedral and half of tetrahedral voids is?
​

Answer 1

Hope you are satisfied.

Answer 2

Given: Atom "B" = ccp arrangement

Atom "A" - half in the tetrahedral void and half in the octahedral void.

To Find: The formula of crystalline solid

Solution:

Concept:

• ccp or cubic closed packing consists of 4 atoms.
• However, the number of octahedral voids is equal to the number of atoms - mostly 4
• The number of tetrahedral voids is equal to double the number of octahedral voids i.e. 2 × 4 = 8.
• Tetrahedral voids are located at 1/3 distance from all corner atoms.

Applying the above concept:-

Number of atoms of B = 4 (ccp)

Number of atoms of A = 4/2 (octahedral voids) + 8/2 (Tetrahedral voids)

Number of atoms of A = 2 + 4 = 6

The Formula of solid = A₆B₄

i.e. A₃B₂ (Dividing each number of atoms by 2)

Hence, The formula of crystalline solid = A₃B₂