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Explain the process and definition of crystallization
Crystallization is the formation of crystals that results when a solid precipitates from a liquid solution or, rarely, directly from a gas. The term is used to describe this process in nature as well as when it occurs in a laboratory or industrial setting. Mineral and organic compounds and even water can be crystallized. Most crystals are some type of compound, but crystals of pure elements are possible. Snowflakes, salt, and some gemstones are formed by this process.

Crystals form when the concentration of a solute reaches a maximum, a condition called supersaturation. Cooling or evaporation of the solution will then trigger the crystallization process. A reduction in temperature can trigger crystal formation because the ability of a solution to hold a solute depends partially on the temperature. As the temperature decreases, so does solubility. Evaporation increases the concentration of the solute in the solution, triggering crystallization.

The first stage in the formation of any crystal is called nucleation. Nucleation is the combination of two or more molecules of the solute. These molecules will attract more molecules, which will bond to the original crystals in a regular pattern. This structure of this pattern, or matrix, is dependent upon the molecular properties of the substance being crystallized but will continue to propagate in a regular way as more molecules are added. This process may continue even after the concentration of dissolved solute drops below the supersaturation point, as the crystal will continue to add more molecules to its matrix.
The most commonly known crystallization process is the formation of water crystals in the atmosphere. This occurs all over the world, on a continuous basis, as air containing water vapour is cooled. the water crystallizes into ice, and as the crystals of water grow, they form snowflakes.


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