Colloid
Somewhere between the sizes of an
atom and a grain of sand lies the realm of small particles called colloids. As
will become evident, they are everywhere. The simplest colloidal materials,
also generally known as suspensions or dispersions, consist of two mixed
phases. The continuous or dispersing phase may be gas, liquid, or solid
(or even plasma, the fourth phase of matter). Air, water, and plastics are
common examples. The colloid particles make up the dispersed or suspended phase
when uniformly distributed in the second, continuous phase. The dispersed matter
may also be gas, liquid, or solid, and any combination in more complex
suspensions. Colloidal dispersions are considered homogeneous mixtures
even though they can be heterogeneous at or below the microscale.
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