AQA GCSE Chemistry key terms

The tendency of a substance to undergo a chemical reaction.

A list of elements arranged in order of reactivity, usually from most reactive to least reactive.

A cell whose chemical reactions can be reversed by supplying an external electrical current, allowing the cell to be used again.

Processing material from a used product to make a new product.

A reaction in which oxidation and reduction occur together because electrons are transferred between particles.

Using less material or fewer products in the first place, reducing demand for raw materials and energy.

The gain of electrons by a substance.

A spectrum from a known substance, used to identify substances in an unknown sample by comparison.

An ordered, repeating arrangement of particles in a solid.

The fibres or fragments held within a composite's matrix.

The mean mass of the atoms of an element compared with one-twelfth of the mass of a carbon-12 atom; its symbol is $A_r$.

The sum of the relative atomic masses of all the atoms shown in a chemical formula. Relative formula mass, $M_r$, has no unit.

The sum of the relative atomic masses of all the atoms shown in a chemical formula.

A mass stated by comparison with an agreed reference rather than in kilograms.

The mass of a molecule compared with one-twelfth of the mass of a carbon-12 atom; it is found by adding the relative atomic masses of all the atoms in the formula.

A resource that is naturally replenished on a human timescale, provided it is not used faster than it is replaced.

The smallest section of a polymer chain whose pattern repeats along the chain.

A measurement made again under the same conditions so that the spread of the results can be assessed.

The smallest group of atoms that repeats along a polymer chain.

The insoluble solid left on filter paper during filtration.

The smallest change that a measuring instrument can distinguish.

Health difficulties affecting breathing or the organs and airways used for breathing.

Using a product again without turning its material into a new product.

A desalination process in which pressure forces water through a partially permeable membrane while dissolved salts are retained.

The reaction in which products re-form the original reactants.

A reaction in which the products can react to form the original reactants.

A unitless ratio equal to the distance moved by a substance divided by the distance moved by the solvent.