How many atoms are effectively contained in a Simple Cubic unit cell?

• A. 1
• B. 2
• C. 3
• D. 4

Answer: (A)

In a Simple Cubic cell, atoms sit only at the eight corners. Each corner atom is shared by eight neighboring unit cells, so its contribution to a single cell is 1/8. Adding up the eight corners gives 8 × 1/8 = 1. There are no atoms fully inside the cell, so the effective number is one.