What is Crystal?

  What is a crystal?

Crystal – A solid of definite shape with its atoms, ions or molecules arranged in some regular repetitious three dimensional patterns is termed as a crystal.

Crystalline solid – The crystalline state of a solid is characterized by regular and periodic arrangement of atoms or molecules when a crystal grows in a constant environment, the shape remains unchanged during growth. It appears as if identical building blocks are continuously added. The building blocks are atoms or group of atoms.

A periodic and regular arrangement of points in space is known as a lattice arrangement. In a crystalline structure, the various atoms and molecules are attached to the lattice in an identical manner. The distances between the various particles constituting a crystal are of the order of the size of these particles. The mean potential energy of every particle is more than its mean kinetic energy and their vibrations about the position of equilibrium are extremely limited. There is always internal regularity of particles, which is responsible for the symmetry of external shapes. A crystal, therefore, presents a sort of spatial regularity extending over a large volume.i.e, a long range order in its structure. The various properties like thermal conductivity, compressibility, tensile strength etc., depend on the structure of the crystal or the arrangement of particles in it. The crustal have generally sharp melting points and get converted into liquid state very soon.