Colloid: definition in chemistry
Colloid: A mixture in which tiny particles, roughly 1 to 1,000 nanometers across, are spread through another substance and do not settle out.
Colloid particles are larger than the molecules in a solution but too small to settle or to be caught by ordinary filter paper. They scatter light, so a beam shining through a colloid becomes visible, an effect called the Tyndall effect. Colloids include foams, emulsions, gels and aerosols, depending on what is dispersed in what.
Examples
- Milk — an emulsion of fat droplets in water
- Fog — tiny water droplets in air
- Whipped cream — a foam of air bubbles in cream
- Gelatin dessert — a gel