The unit cell of sodium chloride NaCl crystal is a face-centered cubic FCC lattice. In this arrangement, each sodium Na+ ion is surrounded by six chloride Cl- ions, and each chloride ion is surrounded by six sodium ions. The coordination number the number of nearest neighbors is 6 for both types of ions. The unit cell consists of 4 sodium ions and 4 chloride ions, with the chloride ions located at the corners and face centers of the cube, and the sodium ions located at the edge centers and the center of the cube.