Face centred cubic structure is a crystal structure with the densest distribution of atoms: next to corners atoms occupy also the centres of all six side planes of the cube.
The atom in the centre of the side plane belongs to two neighbouring cells, therefore one cell contains 1/2 of this atom. Because such atoms are 6, the cell of the face centred cubic structure has 4 atoms (3 from side planes and 1 from corners). Each atom in this crystal structure borders on 12 nearest neighbours.
Into a face centred cubic structure crystallize the elements such as: Al, Cu, Au, Ag,...
