Crystal structure of sodium chloride

Sodium chloride is an tonic compound. The crystal structure of sodium chloride is a typical example of an ionic crystal. Sodium chloride of sodium and chloride ions held together by ionic or electrovalent bond. Sodium chloride is crystallized in a face centered cubic lattice. The entire crystal of sodium chloride can be built by stalking the above unit cell of sodium chloride in three dimension. The sodium chloride crystal may be visualized as consisting of chloride ions at corners of the cube and at the center of the face of the cube. The sodium ion occupying the space at the middle of the edges between the chloride ions and at the center of the cube. A unit cell of sodium chloride may appear to be consisting of 14 chloride ions and 13 sodium ions, but in reality it consists of 4 units of sodium chloride. The chloride at the corner of the cube is shared by 8 other cubes hence 8 chloride ions at eight corner represent only one chloride ion. The chloride at center of the face is shared by two cubes hence the sic chloride ions at center of six faces represent only 3 chloride. Hence all the chloride ions present in a unit cell of sodium chloride represents 4 chloride ions. Similarly, the sodium ion present at the middle of the edge of the cube is shared by four other cubes. Hence the twelve sodium ion present at the middle of twelve edge of the cube represent 3 sodium ion. The sodium ion at center of the cube belongs fully to the cube hence represents one sodium ion. Thus a unit cell of sodium chloride contains 4 sodium ions. In total a unit cell of sodium chloride represents 4 sodium and four chloride ions i.e. 4 units of sodium chloride.

  The crystal of sodium chloride may be visualized in different way as well. If we look at the sodium ion at the center of the cube ( open circle) we readily find that it is surrounded by six chloride ions ( closed circle). Similarly, if we look at any chloride ion it will also be surrounded by six sodium ions octahedrally. Thus sodium chloride crystal may be visualized as consisting of sodium and chloride ions in which each sodium ion is surrounded by six chloride ions and each chloride ion is surrounded by six sodium ions.