What is the coordination number of a body-centered cubic (BCC) lattice?

• A. 6
• B. 8
• C. 12
• D. 14

Answer: (B)

Coordination number is the number of nearest neighboring atoms surrounding a given atom. In a body-centered cubic lattice there are atoms at each corner of a cube and one at the center. The center atom is in contact with all eight corner atoms, so it has eight nearest neighbors. Hence the coordination number is eight. Six would correspond to a simple cubic lattice, while twelve corresponds to a face-centered cubic lattice.