Distinguish between hexagonal close packing and cubic close packing.

1.	Distinguish between hexagonal close packing and cubic close packing.
Answer» Hexagonal close packing 1. aba arrangement 2. In this case, the spheres of the third layer are exactly aligned with those of the first layer 3. In HCP, tetrahedral voids of the second layer may be covered by the spheres of the third layer Cubic close packing: 1. abc arrangement 2. In this case, the spheres of the third layer are not aligned with those of the first layer or second layer. Only when fourth layer is placed, its spheres are aligned with the first layer 3. In cep third layer may be placed above the second layer in a manner such that its sphere cover the octahedral voids

Answer»

Hexagonal close packing

1. aba arrangement

2. In this case, the spheres of the third layer are exactly aligned with those of the first layer

3. In HCP, tetrahedral voids of the second layer may be covered by the spheres of the third layer

Cubic close packing:

1. abc arrangement

2. In this case, the spheres of the third layer are not aligned with those of the first layer or second layer. Only when fourth layer is placed, its spheres are aligned with the first layer

3. In cep third layer may be placed above the second layer in a manner such that its sphere cover the octahedral voids

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