chimie colloïdale

Traductions

• anglais

  Date : 1983

  Définition

  The study of phenomena occurring when any form of matter has at least one dimension that is less than 1 micron (the limit of resolution of the optical microscope) and more than 1 millimicron (10 angstrom), which is the approximate size of an average molecule. Thus, it is concerned with the size range that lies between molecular dimensions and particles that are just visible in a compound microscope. (Colloidal particles can be seen in the electron microscope, however).

  Note :

  It is important to note that in colloid chemistry it is the dimension that is significant, rather than the nature of the material; thus it involves not only particulate matter but films, foams, fibers, interfaces, and surface irregularities such as occur, for example, in catalysts. Materials having emulsifying action (chiefly proteins) are called protective colloids. The term was first used in 1860 by Thomas Graham, a Scottish chemist (1805-1869), to distinguish materials that would not pass through a parchment membrane; as many of these were stickly and glue-like, the named them "colloids", a term derived from the greek word for "glue". Materials that passed through the membrane he called crystalloids. The physical chemistry of colloids is highly complex, involving electrical charges, adsorption, solvation, surface and interfacial tension and other physicochemical phenomena.

  Terme :

  1. colloid chemistry