The diagram below shows a space-filling diagram of a face-centered cubic unit cell cut
to show only the part of each atom that is inside the unit-cell boundaries. The corner
atoms are each shared among eight unit cells, so , of tne atom is in the unit cell shown.
The face-centered atoms are shared between two unit cells, so I of the atom is in the
unit cell shown. The eight corners of the unit cell then total 8 x ,!-= 1 atom, and the six
faces total 6 x | : 3 atoms; a total of four atoms are in the unit cell