Atoms touch each other along face diagonals. All atoms are
identical; the face-centered atoms are shaded differently only for ease of
viewing.
ex: Al, Cu, Au, Pb, Ni, Pt, Ag
Coordination no = 12
4 atoms/unit cell: 6 face x 1/2 + 8 corners x 1/8
Atomic Packing Factor for a face-centered cubic structure =
0.74
Close-packed directions: length = 4R = sqrt (2a)
Unit cell contains: 6 x 1/2 + 8 x 1/8 = 4 atoms/unit cell
