How many atoms are contained in one conventional unit cell of a simple cubic lattice?

• A. 2
• B. 1
• C. 3
• D. 4

Answer: (B)

In a simple cubic lattice, atoms sit at the eight corners of the cube, and each corner atom is shared by eight neighboring unit cells. So only 1/8 of each corner atom belongs to a given cell. With eight corners, the total contribution is 8 × (1/8) = 1 atom per conventional unit cell. Therefore the cell contains one atom overall. (For comparison, a body-centered lattice has two atoms per cell, and a face-centered lattice has four.)