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GCSE Chemistry · key term
An atom, ion or molecule taking part in a chemical reaction.
Used by AQA, Edexcel and OCR
Specification 4.4.1.4 · Paper 1
Revise: Redox and ElectronsAn electron lost by one species has to be gained by another, so the complete change is called a redox reaction. The species losing electrons is oxidised, while the species gaining them is reduced.
Specification 4.5 · Paper 1
An atom, ion or molecule involved in a chemical reaction.
Specification C3.3b, C4.2d · Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
Revise: Redox: Electron TransferIn an electron-transfer reaction, one species gives them up and another takes them in. Oxidation and reduction therefore happen together: this is a redox reaction. To identify what has been oxidised or reduced, follow the electrons from the starting species to the products.
A chemical entity, such as an ion, molecule or element, whose identity can be inferred from characteristic test results.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
Revise: Reduction and oxidationTo describe that change, focus on which species gains or loses electrons.
An atom, ion, molecule or compound taking part in a chemical reaction.
Name the species that changes, not the electron: for example, magnesium is oxidised and copper(II) ions are reduced.
Only cancel a spectator ion if the identical species, including its charge, appears on both sides of the equation.
Identify the species that loses or gains electrons, then name the process. Do not decide from the word ‘oxygen’ alone when the question asks for an electron explanation.
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