Question

What is the coordination number of an atom in a Face-Centered Cubic (FCC) crystal structure?

• A. 6
• B. 8
• C. 12
• D. 4

Hint:

Coordination numbers of common crystal structures: Simple Cubic (SC) → 6 Body-Centered Cubic (BCC) → 8 Face-Centered Cubic (FCC) → 12

Answer 1

The Correct Option is C

Concept: The coordination number of a crystal structure is the number of nearest neighboring atoms surrounding a given atom. In a Face-Centered Cubic (FCC) structure:
• Atoms are located at the corners of the cube.
• Additional atoms are located at the center of each face. Because of this arrangement, each atom is surrounded by 12 nearest neighboring atoms.

Step 1: Understand the FCC arrangement. In an FCC lattice, atoms are present at:
• 8 cube corners
• 6 face centers

Step 2: Determine nearest neighbors. Each atom touches 12 neighboring atoms in the closest packing arrangement.

Step 3: State the coordination number. \[ \boxed{\text{Coordination number} = 12} \]