Gel Definition in Chemistry

Blue gel

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A gel is a sol in which the solid particles are meshed such that a rigid or semi-rigid mixture results. Cross-linking within the gel's polymer or colloidal network causes a gel to behave as a solid in its steady-state and makes it feel tacky. However, most of the mass of a gel is liquid, so gels can flow from application of relatively low stress.

19th-century Scottish chemist Thomas Graham coined the word "gel" by shortening the word "gelatine."

Gel Examples

Fruit jelly is an example of a gel. Cooked and cooled gelatin is another example of a gel. The protein molecules of gelatin cross-link to form a solid mesh which contains pockets of liquid.


  • Ferry, John D. Viscoelastic Properties of Polymers. New York: Wiley. (1980). ISBN 0471048941.
  • Khademhosseini, A. und U. Demirci. Gels Handbook: Fundamentals, Properties and Applications. World Scientific Pub Co Inc. (2016). ISBN 9789814656108.