Question

Explain with a diagram the hcp mode of packing in crystals. 

Answer 1

The hcp (hexagonal close packing) is one of the most efficient ways to pack spheres (atoms or ions) in a crystal. It ensures maximum use of available space and is commonly found in metals like magnesium (Mg), zinc (Zn), and titanium (Ti).

1. First Layer (A): Atoms are arranged in a hexagonal 2D pattern. Each atom touches six others.
2. Second Layer (B): Atoms are placed in the depressions of the first layer, fitting into the gaps.
3. Third Layer (A): This layer is placed exactly above the first layer, repeating the ABABAB… pattern.