Heterogeneous Definition (Science)

The word heterogeneous is an adjective that means composed of different constituents or dissimilar components.

In chemistry, the word is most often applied to a heterogeneous mixture. This is one which has a non-uniform composition. A mixture of sand and water is heterogeneous. Concrete is heterogeneous. In contrast, a homogeneous mixture has a uniform composition. An example is a mixture of sugar dissolved in water. Whether a mixture is heterogeneous or homogeneous is largely dependent on the scale or sample size. For example, if you look at a container of sand, it may appear to have evenly distributed particles (be homogeneous). If you viewed the sand under a microscope, you might find unevenly distributed clumps of different materials (heterogeneous).

In materials science, specimens may consist entirely of the same metal, element, or alloy, yet display heterogeneous phases or crystal structure. For example, a piece of iron, while homogeneous in composition, might have regions of martensite and others of ferrite. A sample of the element phosphorus might contain both white and red phosphorus.

In the broader sense, any group of dissimilar objects may be described as being heterogeneous. A group of people might be heterogeneous with respect to age, weight, height, etc.