In the ccp packing, the number of lattice points per unit area in the planes is in the order

Question

Question

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CSIR-UGC (NET) Chemical Science: Held on (26 Nov 2020)

Answer 1

Concept:

Cubic Close Paking:

The cubic close packing (ccp) is the name given to a crystal structure. When we put atoms in the octahedral void, the packing is the of the form ABCABC, the packing is known as cubic close packing (ccp).

Explanation:

In case of (100) plane, 5 lattice points are present in the area is a². Thus, the area occupied by 1 lattice point is (a²/4)=0.20a².
In case of (110) plane, 6 lattice points are present in the area is Thus, the area occupied by 1 lattice point is =0.23a².
In case of (111) plane, 6 lattice points are present in the area . Thus, the area occupied by 1 lattice point is = 0.14a².
Thus, In the ccp packing, the number of lattice points per unit area in the planes is in the order (111) > (100) > (110).

Conclusion:-

So, In the ccp packing, the number of lattice points per unit area in the planes is in the order (111) > (100) > (110)