• Unit cells make up the smallest structural units within a crystal solid material.crystal image by matko from Fotolia.com
  
  Gases, liquids and solids make up the basic types of matter within the physical environment. These materials differ in their atomic structures, which accounts for their varying degrees of density. Unit cells appear in symmetrical patterns within crystal solids to form tightly woven atomic structures. These patterns run throughout the shape of a crystal and produce a finely structured shape and appearance.
  
  

Structure

• A unit cell constitutes the smallest, three-dimensional component within a crystal solid. The cell itself is made up of a group atoms bonded together in a geometrical pattern. A succession of unit cells forms a lattice, or network of unit cells that fall within fixed intervals. According to the University of California at Santa Barbara, this arrangement produces the highly ordered molecular appearance found inside crystalline structures. In effect, unit cells combine to form a densely packed solid, giving it a rigid structure that resists compression. The patterns formed by unit cells can appear in orderly fashion across the three dimensions of height, width and depth. In effect, a unit cell is the smallest representation of a crystal solid and determines the overall structure of the whole mineral, according to Crystallography, a mineral rock resource site.
  
  

Shape

• The atoms contained inside a unit cell are arranged in a box-like shape. The number of atoms can range anywhere from four to 1000 and varies according to the type of crystal. Within each unit, atoms appear in a fixed geometrical pattern in relation to one another, which gives unit cells a parallel-sided shape. When stacked together within a three-dimensional space, a lattice pattern emerges. According to Oklahoma State University, the geometrical shape of a unit cell can reproduce only so many times within a three-dimensional space, which restricts the type of shape a crystal can form. When combined within a three-dimensional shape, unit cells share portions of their atoms with neighboring cells due to the overlapping nature of their atomic bonds.
  
  

Symmetry

• The properties of a unit cell account for the fine symmetry that appears within a crystalline structure. According to the International Society for Complexity, Information and Design, the symmetrical effect results from the repetitive patterns created by the structural bonds form the network of atoms within a crystal. The three-dimensional aspect of this network produces two types of symmetry within a crystal: translational and point symmetries. Translational symmetry refers to the pattern effect created across the length or depth of a crystal. Point symmetry refers to the patterns that emerge around each unit cell structure. Point symmetry account's for how a crystal material reflects and absorbs light rays.