A geometric arrangement of the points in space at which the atoms, molecules, or ions of a crystal occur.

The regular pattern of atoms, ions, or molecules in a crystalline substance. A crystal lattice can be regarded as produced by repeated translations of a unit cell of the lattice. See also crystal system.

Three-dimensional configuration of points connected by lines used to describe the orderly arrangement of atoms in a crystal. Each point represents one or more atoms in the actual crystal. The lattice is divided into a number of identical blocks or cells that are repeated in all directions to form a geometric pattern. Lattices are classified according to their dominant symmetries: isometric, trigonal, hexagonal, tetragonal, orthorhombic, monoclinic, and triclinic. Compounds that exhibit a crystal-lattice structure include sodium chloride (table salt), cesium chloride, and boron nitride.