Here is a list of all the definitions you have to know for A2 Chemistry paper 4. You will do well to memorise all of them.
Ka - Equilibrium constant for the dissociation of a weak acid.
Bidentate - Ligand that forms 2 dative bonds with a transition metal ion.
Buffer - A solution that resists changes in pH when small amounts of acids and bases are added.
Chelates - Complexes with polydentate ligands.
Common ion effect - The effect of precipitating an ionic compound when the equilibrium is affected by the addition of a common ion to the system.
Complex ion - A central transition metal ion that is surrounded by ligands bonded to it via dative bonds.
Degenerate orbitals - A set of orbitals of exactly the same energy level.
Entropy - The total number of possible arrangements of particles and their energy in a system.
Enthalpy change of solution - Enthalpy change when 1 mol of a substance dissolves in water to form a dilute solution.
Enthalpy change of atomisation - Enthalpy change when 1 mol of an element in its standard state is atomised to form 1 mol of gaseous atoms.
Enthalpy change of hydration - Enthalpy change when 1 mol of gaseous ions dissolves in water to form a very dilute solution.
Faraday constant - Electric charge needed to produce 1 mol of atoms of a product from singly charged ions during electrolysis.
First electron affinity - Energy released when 1 mol of gaseous atoms each accepts an e- to form 1 mol of gaseous ions with a single negative charge.
Half-life - Time taken for the concentration of a reactant to decrease to half of its initial value.
Ionic product of water - Equilibrium constant for the dissociation of water.
Isoelectric point - pH at which an amino acid is neutral.
Ligand - A species that contains a lone pair of e- that forms a coordinate bond to a central metal ion.
Monodentate - A ligand that donates a single lone pair of e- to form a dative bond with a transition metal ion.
Non-degenerate orbitals - A set of orbitals split into groups with slightly different energy levels.
Order of a reaction - Power to which the concentration of a reactant is raised in the rate equation.
Overall order of a reaction - The sum of the powers of all reactants in the rate equation.
Partition coefficient - The ratio of the concentrations of a solute in two immiscible liquids at dynamic equilibrium.
Polydentate ligand - A ligand that donates two or more lone pairs to form 2 or more dative bonds with a transition metal ion.
Rate determining step - Slowest step in the reaction mechanism.
Solvent front - Furthest point reached by a solvent in paper or TLC.
Stability constant - Equilibrium constant for the formation of a complex ion.
Standard cell potential - Voltage when two standard cells are connected together.
Standard electrode potential - Voltage of a half-cell when connected to a standard hydrogen electrode in standard conditions.
Standard hydrogen electrode - Electrode consisting of a platinum metal dipped in a solution of 1 mol dm⁻³ H⁺ ions through which H₂(g) is bubbled at 298K and 1 atm.
Stationary phase - Solid or porous solid used in chromatography to separate mixtures.
Retention time - Time taken for a component in a mixture to pass through a chromatography column.
Thin layer chromatography - Chromatography technique where the stationary phase is a glass, metal, or plastic sheet coated with a thin layer of porous solid.
Zwitterion - A molecule with both a permanent positive and negative charge.