This page summarises the transition metals section of the A-level inorganic chemistry curriculum, showing the main concepts, reactions, and skills commonly required across AQA, Edexcel, and OCR.
Transition metals commonly form complexes, show variable oxidation states, produce coloured ions, and behave as catalysts.
Students learn the meaning of ligand, complex ion, and coordination number.
Typical ligands include H2O, NH3, Cl−, and OH−.
You should recognise octahedral, tetrahedral, and square planar complexes, as well as cis-trans and optical isomerism.
Transition metal ions are often coloured because ligands split the d-orbital energy levels, allowing electrons to absorb visible light and move to higher energy states.
Water ligands in aqua ions can be replaced by other ligands such as ammonia or chloride, often causing visible colour changes.
Bidentate and multidentate ligands can form more stable complexes. This increased stability is explained by the chelate effect.
Important ions include Cu2+, Fe2+, Fe3+, Cr3+, and sometimes Mn2+ or Co2+. Students should know precipitates, colour changes, and the effect of excess reagent.
A-level courses often include vanadium oxidation states from +5 to +2, and may also cover chromate/dichromate equilibria and related redox changes.
Examples include V2O5 in the Contact process, Fe in the Haber process, Fe2+ as a homogeneous catalyst, and Mn2+ in autocatalysis.