Iron and copper chemistry

Iron and copper were first encountered during AS Chemistry’s ‘Extraction of Metals‘ topic. The link between both metals being exemplified by the use of scrap iron to extract copper from copper (II) ions: Fe(s) + Cu2+(aq) → Cu(s) + Fe2+(aq) (blue)                        (green) This method of copper extraction, usually from low-grade

Chromium, cobalt, vanadium and manganese chemistry

At lower oxidation states, transition metals form ionic bonds e.g. Mn2+ and Cr3+  At higher oxidation states, transition metals cannot form monatomic ions. Instead they bond covalently with electronegative elements (like oxygen) to form compounds or molecular ions e.g. oxoanions such as MnO4−and Cr2O72-. In general,  Reduction, from high to low metal oxidation state, is more feasible in acidic transition

Catalysts (transition metals)

Mechanism of catalysis The minimum energy required for reactants to undergo a chemical reaction is known as the Activation Energy (Ea). A catalysed reaction provides an alternative route for the chemical reaction at a lower activation energy, hence increases the rate of reaction. Transition metals, by virtue of their ability to readily change their oxidation states, generate intermediate species that enable the

Variable oxidation states (transition metals)

Transition elements show variable oxidation states, as electrons may be lost from energetically similar 4s and 3d sub-levels. Terminology: the oxidation state of the metal in a compound is indicated by a Roman numeral after the name of the metal. So Iron (II) means a compound containing Fe2+ .  Oxidation states of chromium Species Colour Oxidation state of metal K2CrO4

Formation of coloured ions

Transition metal ions can be identified by their colour Why transition metals form coloured complexes? 1. Complexes shows different energy levels for its d electrons due to d orbital splitting. Metal ions, with incompletely filled d sub-orbitals, experience energetic splitting of their five d sub-orbitals upon binding with ligands. Two groups of d sub-orbitals are formed: one group will be