Facts At Your Fingertips: Matter and materials – Mixtures and compounds
Different elements can be combined to create new substances. When atoms and molecules chemically combine to form a substance, it is called a compound.
If no chemical reaction takes place—as when mud is added to water—a mixture is formed.
Compounds
These are often very different from the elements that make them up. Hydrogen and oxygen are invisible and odorless gases.
However, when chemically combined, the two create a simple compound called water.
Mixtures
There are two main types of mixture: solutions and suspensions. In a solution, a substance breaks up into individual atoms or molecules and mixes evenly in another substance, known as the solvent.
In a suspension, a substance does not break up completely and may still be floating in the liquid as solid particles.
Alloys
Metals can be mixed with each other, or with other substances, to create a new substance called an alloy.
Alloys have different properties from the substances they are composed of. For example, the alloy bronze is much harder than the metals that make it up—copper and tin.
Separating mixtures
Several methods can be used to separate substances in a mixture, including evaporation, spinning, filtration, and distillation.
The last method involves heating a mixture so that a substance with a lower boiling point can be collected as a gas from the mixture, leaving behind the substance (or substances) with the higher boiling point.
Pure water can be obtained from salty water by distillation.