Crystal structure

unique arrangement of atoms or molecules in a crystalline liquid or solid

In crystallography, the crystal structure is how the atoms (or ions or molecules) are arranged in a crystalline material.[3] Crystals occur naturally from the way the chemical bonds of the atoms connect. Symmetric repeating patterns occur in 3-D space in the crystal.

The (3-D) crystal structure of H2O ice Ih (c) consists of bases of H2O ice molecules (b) located on lattice points within the (2-D) hexagonal space lattice (a). The values for the H–O–H angle and O–H distance have come from Physics of Ice[1] with uncertainties of ±1.5° and ±0.005 Å, respectively. The white box in (c) is the unit cell defined by Bernal and Fowler[2]

The crystal structure and symmetry cause many physical properties, such as cleavage (how the crystal splits) how it conducts electricity, and its optical properties..

The crystal structure of a chemical is the shape of the crystal at the molecular level. There are several shapes of crystals. Sodium chloride is a cube. Copper sulfate is triclinic. Most things, even metals, have crystal structures. Some crystals fit more atoms in them than others, and these crystals usually weigh more.


  1. Petrenko, V. F.; Whitworth, R. W. (1999). Physics of Ice. Oxford University Press. ISBN 9780198518945.
  2. Bernal, J. D.; Fowler, R. H. (1933). "A Theory of Water and Ionic Solution, with Particular Reference to Hydrogen and Hydroxyl Ions". The Journal of Chemical Physics. 1 (8): 515. Bibcode:1933JChPh...1..515B. doi:10.1063/1.1749327.
  3. Hook, J.R.; Hall, H.E. (2010). Solid State Physics. Manchester Physics Series (2nd ed.). John Wiley & Sons. ISBN 9780471928041.