Nucleation Definition (Chemistry and Physics)

Nucleation Definition

Nucleation is the process where droplets of liquid can condense from a vapor, or bubbles of gas can form in a boiling liquid. Nucleation can also occur in crystal solution to grow new crystals. It is seen in gases when tiny bubbles coalesce into larger ones. In general, nucleation is a self-organizing process that leads to a new thermodynamic phase or a self-assembled structure.

Nucleation is affected by the level of impurities in a system, which can provide surfaces to support assembly. In heterogeneous nucleation, organization begins at nucleation points on surfaces. In homogeneous nucleation, organization occurs away from a surface. For example, sugar crystals growing on a string is an example of heterogeneous nucleation. Another example is the crystallization of a snowflake around a dust particle. An example of homogeneous nucleation is growth of crystals in a solution rather than a container wall.

Examples of Nucleation

• Dust and pollutants provide nucleation sites for water vapor in the atmosphere to form clouds.
• Seed crystals provide nucleation sites for crystal growing.
• In the Diet Coke and Mentos eruption, the Mentos candies offer nucleation sites for the formation of carbon dioxide bubbles.
• If you place your finger in a glass of soda, carbon dioxide bubbles will nucleate around it.

Sources

• Pruppacher, H. R.; Klett J. D. (1997). Microphysics of Clouds and Precipitation.
• Sear, R.P. (2007). "Nucleation: theory and applications to protein solutions and colloidal suspensions" (PDF). Journal of Physics: Condensed Matter. 19 (3): 033101. doi:10.1088/0953-8984/19/3/033101