Edexcel GCSE Chemistry key terms

A subatomic particle in the nucleus with a relative charge of +1.

Indirect evidence used to estimate past conditions when direct measurements are unavailable, such as evidence from tree rings or gases trapped in ice cores.

A substance containing only one element or one compound, with the same composition throughout.

The use of observations from chemical tests to determine which substances or ions are present.

Descriptive, non-numerical information about a property, such as whether a material is transparent or brittle.

A test that identifies a substance from a characteristic observation, such as a particular precipitate colour or a gas-test result.

Information expressed using numbers and units, such as energy use in MJ or carbon dioxide emissions in kg.

The transfer of energy by electromagnetic waves, requiring no particles or direct contact.

The distance from the centre of a sphere or approximately spherical object to its edge.

The change in the amount of reactant used or product formed per unit time.

A comparison showing the relative amounts of two or more quantities. In a balanced chemical equation, the coefficients give the ratio of amounts in moles.

A naturally occurring material from which useful products are made; metal ores are finite raw materials.

The substances or materials obtained to make a product, such as metal extracted from an ore.

A substance that is used up during a chemical reaction.

The substances present at the start of a chemical reaction.

The ratio of the masses of substances that react or form, calculated from a balanced equation and their relative formula masses.

The arrow pointing from reactants to products; it can be read as “produces” or “forms”.

Factors such as temperature and the presence or removal of substances that affect how a reaction proceeds.

A series of reactions used to convert starting materials into a specified desired product.

A graph showing how the energy changes as a reaction progresses from reactants to products.

How readily a substance undergoes a chemical reaction.

An arrangement of metals in order of their tendency to react and to form positive ions, with the most reactive at the top.

Processing a used material so that it can be made into a new product.

Indicator paper that turns blue under alkaline conditions.

A reaction in which oxidation and reduction happen together through electron transfer.

A substance that causes another substance to be reduced and is itself oxidised.

Gain of electrons by a particle.