AQA GCSE Chemistry key terms

Combustion in a plentiful supply of oxygen, so the carbon and hydrogen in a hydrocarbon are fully oxidised to carbon dioxide and water.

A material containing two or more distinguishable materials whose properties work together.

The substances present in something and the proportions of each.

A substance containing two or more different elements chemically combined.

A material's ability to withstand a pushing force without being crushed or deformed.

A solution containing a relatively large amount of dissolved substance per unit volume.

The amount of dissolved substance in a given volume of solution.

A change from a gas to a liquid, such as water vapour forming liquid water as it cools.

A type of polymerisation in which monomers with two functional groups join and a small molecule, usually water, is formed at each new link.

The change of state from a gas to a liquid.

The principle that energy cannot be created or destroyed, although it can be transferred between stores and between a system and its surroundings.

The principle that atoms are neither created nor destroyed in a chemical reaction, so the total mass of reactants equals the total mass of products.

Unwanted material introduced into a sample or apparatus, which may produce a misleading result.

A relationship in which two measured variables change together; it does not, by itself, show that one causes the other.

The gradual destruction of a material through chemical reactions with substances in its environment.

A bond formed by the electrostatic attraction between two positive nuclei and a shared pair of electrons.

A strong bond formed when atoms share a pair of electrons.

The breakdown of large hydrocarbon molecules into smaller, more useful molecules.

A substance added to dissolve aluminium oxide and lower the temperature needed for electrolysis.

The formation of solid crystals from a solution, usually after concentrating the solution and allowing it to cool.

An electron that is not confined to one bond and can move through part of a structure.

Electrons that are not tied to one atom or one bond and can move through a structure.

Mass per unit volume. A denser material contains more mass in the same volume.

The removal of dissolved salts from salty or sea water.

The product that the reaction is intended to make.

A molecule containing two atoms joined by a covalent bond.

A solution containing a relatively small amount of dissolved substance per unit volume.