{"term":{"id":"02055","title":"embryo","longtitle":"IUPAC Gold Book - embryo","doi":"10.1351\/goldbook.E02055","code":"E02055","status":"current","also defines":"<em>also defines<\/em>: critical embryo, homogeneous nucleus","definitions":[{"id":1,"text":"An aggregate of a small number of atoms, molecules or ions. An embryo of such a size that the Gibbs energy at constant pressure and temperature is a maximum is called a critical embryo. An embryo larger than a critical embryo is called a homogeneous nucleus. Colloidal sols may be formed by condensation methods. When a condensation method is applied, molecules (or ions) are deposited on nuclei which may be of the same chemical species as the colloid (homogeneous nucleation) or different (heterogeneous nucleation).","links":[{"term":"Colloidal sols","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/C01172"},{"term":"colloid","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/C01171"},{"term":"heterogeneous nucleation","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/H02807"},{"term":"homogeneous nucleation","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/H02848"}],"sources":["PAC, 1972, 31, 577. 'Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry' on page 608 (https:\/\/doi.org\/10.1351\/pac197231040577)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/E02055\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/E02055\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/E02055\/plain"},"citation":"Citation: 'embryo' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351\/goldbook.E02055","license":"The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/) for individual terms.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","disclaimer":"The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.","accessed":"2026-06-30T17:17:57+00:00"}}