Crystal structure: a combination of motif and point lattice
Motif is defined as a unit or a pattern. For a crystal, it can be an atom, an ion or a group of atoms or ions or a formula unit or formula units. Often it is also called as Basis.
When motif replaces points in a periodic point lattice, it gives rise to what is called as acrystal with a defined structure.
Figure 1.3 Formation of a periodic crystal structure