Question

Primitive cell has ... lattice point per unit cell.

• A. One
• B. Two
• C. Three
• D. Four

Hint:

A unit cell is the smallest repeating structure of a crystal lattice, and when this unit cell has its lattice points at the corners, it is called a primitive cell and the structure can be reproduced in three dimensions to get a 3D lattice of the crystal, by translation.

Answer 1

The Correct Option is A

A primitive cell (also known as a simple cell) is a unit cell that contains only one lattice point. This lattice point is considered to be at the corners of a 3D unit cell. In other words, each corner of the primitive unit cell is shared by 8 adjacent unit cells. Since the corners are shared, the total number of lattice points contributed by each of the 8 corners is:
\(8 \times \frac{1}{8} = 1\)
Therefore, a primitive cell contains only one lattice point per unit cell. Simple cubic structures are examples of primitive cells.
In contrast, body-centered and face-centered unit cells have more than one lattice point per unit cell since there are lattice points at the cell centers or faces as well as the corners.