OCR GCSE Chemistry B key terms

The ability of a method to detect a substance even when only a very small amount is present.

Two electrons shared between bonded atoms; one shared pair forms one covalent bond.

A melting interval covering only a very small temperature range, characteristic of a pure substance.

The reduction in the nucleus’s attraction for an outer electron caused by electrons in inner shells.

The importance or meaning of a result in its context. It depends on more than numerical size alone.

A digit that contributes to the stated precision of a value, counted from the first non-zero digit.

A method of separating a solvent from a solution by vaporising it, then condensing and collecting the vapour.

A substance made of separate, small molecules whose atoms are joined by covalent bonds.

A discrete group of atoms joined by strong covalent bonds.

A covalent bond formed from one shared pair of electrons.

A covalent bond containing one shared pair of electrons.

A material or process that removes a substance faster than it is released; early rocks acted as sinks for atmospheric oxygen.

A harmful mixture of gases and particles that accumulates in the air, often including pollutants formed through reactions involving nitrogen oxides.

A factor concerning communities or groups, such as public acceptance, access, fairness, employment or effects on quality of life.

A temperature at which a material becomes less rigid and more easily deformed; this does not necessarily mean that it melts.

A state in which particles are closely packed in a regular arrangement and vibrate about fixed positions.

The ability of a solute to dissolve in a particular solvent at a particular temperature.

A salt that dissolves in water to form a solution.

The substance that is dissolved in a solvent.

A mixture formed when a solute dissolves in a solvent.

A substance that dissolves another substance to form a solution.

The furthest point reached by the moving solvent on a chromatogram.

A model that shows the positions, arrangement, shape or relative orientation of parts of a system.

An atom, ion, molecule or compound taking part in a chemical reaction.

A list of the properties or performance requirements that a material or product must meet for a particular use.

A catalyst that increases the rate of one reaction may have little or no effect on another reaction.

The entity being counted, such as an atom, molecule, ion or formula unit.