The Crystal Structure of Sodium Chloride
The Crystal Structure of Sodium Chloride
Sodium chlorideforms crystals with face-centered cubic symmetry. In these, the larger chloride ions, shown to the right as green spheres, are arranged in a cubic close-packing, while the smaller sodium ions, shown to the right as silver spheres, fill all the cubic gaps between them. Each ion is surrounded by six ions of the other kind; the surrounding ions are located at the vertices of a regular octahedron. This same basic structure is found in many other minerals and is commonly known as the halite or rock-salt crystal structure. It can be represented as a face-centered cubic (fcc) lattice with a two atom basis or as two interpenetrating face centered cubic lattices. The first atom is located at each lattice point, and the second atom is located half way between lattice points along the fcc unit cell edge.
It is held together by an ionic bond which is produced by electrostatic forces arising from the difference in charge between the ions. Although, Sodium chlorideretains its ionic character in vapor form, at sufficiently low pressures a fraction of it may exist as discrete covalent molecules.
It is held together by an ionic bond which is produced by electrostatic forces arising from the difference in charge between the ions. Although, Sodium chlorideretains its ionic character in vapor form, at sufficiently low pressures a fraction of it may exist as discrete covalent molecules.