Question

The relationship between atomic radius (r) and lattice parameters (a) for a simple cubic (SC) structure is

• A. a = 2r
• B. a = 4r
• C. a = r/2
• D. a = r

Hint:

In simple cubic (SC) structures, atoms only touch along the cube edges. This makes a = 2r. SC structures are rare in nature because their packing efficiency is very low (approximately 52%), meaning most of the space in the unit cell is empty.

Answer 1

The Correct Option is A

In a simple cubic arrangement, atoms touch along the unit cell edges. This means the lattice parameter (a) equals twice the atomic radius (r):
a = 2r