1b) Elements compounds and mixtures_241211_154755

Element

A substance made from only one type of atom.

Compound

A substance made from two or more elements that have reacted chemically with each other.

Mixture

Consists of two or more elements or compounds not chemically combined together; chemical properties of each substance in the mixture remain unchanged.

Pure substance

A single element or compound, not mixed with any other substance.

Melting point

The specific temperature at which a pure substance changes from solid to liquid.

Boiling point

The specific temperature at which a pure substance changes from liquid to gas.

Simple distillation

A technique used to separate a solvent from a solution, based on differences in boiling points.

Fractional distillation

A method used to separate a pure liquid from a mixture of liquids based on their differing boiling points.

Filtration

A technique used to separate a solid (precipitate) from a liquid solution by using a filter.

Crystallisation

A process of separating a soluble salt from a solution by evaporating the solvent to form crystals.

Paper chromatography

An analytical technique used to separate mixtures and identify substances based on their relative speeds in a solvent on paper.

Rf value

The ratio used in chromatography to identify components of a mixture, calculated as distance moved by substance / distance moved by solvent.