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.
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Helmenstine, Anne Marie, Ph.D. "Gel Definition in Chemistry." ThoughtCo, Aug. 29, 2020, Helmenstine, Anne Marie, Ph.D. (2020, August 29). Gel Definition in Chemistry. Retrieved from Helmenstine, Anne Marie, Ph.D. "Gel Definition in Chemistry." ThoughtCo. (accessed March 9, 2021).