S1.1 The Nature of Matter

Matter

Anything that has mass and occupies space

Elements

The primary constituents of matter, which cannot be chemically broken down into simpler substances

Compounds

They consist of atoms of different elements chemically bonded together in a fixed ratio

Mixtures

A combination of two or more different chemical substances which are not chemically bonded and can therefore be separated.

Homogeneous mixture

Has uniform composition and properties throughout

Heterogeneous mixture

Has non-uniform composition and varying properties

Distillation

Where the components of a liquid mixture are vaporised (evaporation) and then condensed (condensation) and isolated. The substance with the lowest boiling point is collected first

Filtration

The separation of an insoluble solid from a liquid or solution. The clean liquid/solution is called filtrate. The remaining solid is called the residue

Solvent extraction/solvation

The separation of different components by a difference in density.

Evaporation

Heating the solution until the solvent evaporates, leaving behind the solid residue.

Crystallisation

The process of formation of solid crystals from solution, melt or by deposition directly from a gas phase

Recrystallisation

Used to remove impurities that are mixed in with a solid. Uses the varied solubilities of solids at different temperatures to separate them

Chromatography

Used to separate a mixture of solutes in a solvent. The components of the mixture move through the stationary phase at different rates due to differences in solvation

Kinetic theory of matter

The idea that matter is composed of tiny particles that are always in motion

Temperature

A measure of the average kinetic energy of particles

What factors can affect the choice of which separating technique to use?

Physical and chemical properties of the substances

State of substance

Availability of equipment and resources

Desired outcome of the process