Colloids are mixtures whose particles are smaller than particles but larger than the size of a molecule which can be seen with the naked eye. Colloids are 1 of 3 major types of mixtures, the other 2 being solutions & suspensions. The 3 types of mixtures are distinguished by the size of the particles that make them up. The particles in a solution are about the size of molecules, approximately 1 nanometer 1 billionth of a meter in diameter. Those which make up suspensions are larger than 1,000 nanometers. Finally, colloidal particles range in size between 1 & 1,000 nanometers. Colloids are said to be as colloidal dispersions because the particles of which they are made are dispersed, or spread out, through the mixture.
Types of colloids
Some examples include mayonnaise, milk, butter, gelatin, jelly, whipped cream, muddy water, plaster, colored glass, & paper.
Every colloid consists of 2 parts: colloidal particles & the dispersing medium. The dispersing medium is the substance in that the colloidal particles are distributed. In muddy water, the best example, the colloidal particles are tiny grains of sand, clay & silt. The dispersing medium is the water in that these particles are suspended.
Colloids can be made from almost any combination of gas, solid & liquid. The particles of that the colloid is made are called the dispersed material. Any colloid consisting of a solid dispersed in a gas is said to be as smoke. A liquid dispersed in a gas is considered to as a fog.
| Dispersing medium | Dispersed phase | Name |
| Solid | Solid | Solid sol |
| Solid | Liquid | Gel |
| Solid | Gas | Solid foam |
| Liquid | Solid | Sol |
| Liquid | Liquid | Emulsion |
| Liquid | Gas | Foam |
| Gas | Solid | Solid aerosol |
| Gas | Liquid | Aerosol |
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