A pair of two species that transform into each other by gain or loss of a proton.
The minimum energy required to start a reaction by the breaking of bonds.
A very long molecular chain, formed by repeated addition reactions of many unsaturated alkene molecules (monomers).
A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule.
The process that occurs when a gas, liquid or solute is held to the surface of a solid or, more rarely, a liquid.
A hydrocarbon with carbon atoms joined together in a ring structure.
A hydrocarbon with carbon atoms joined together in straight or branched chains.
A type of base that dissolves in water to form hydroxide ions, OH–(aq) ions.
The homologous series with the general formula: CnH2n+2.
An alkane with a hydrogen atom removed, e.g. CH3, C2H5; any alkyl group is often shown as ‘R’.
Amount of substance
The quantity whose unit is the mole. Chemists use ‘amount of substance’ as a means of counting atoms.
A substance that contains no water molecules.
A negatively charged ion.
Atomic (proton) number
The number of protons in the nucleus of an atom.
A region within an atom that can hold up to two electrons with opposite spins.
Average bond enthalpy
The average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in the molecules of a gaseous species.
Avogadro’s constant, NA
The number of atoms per mole of the carbon-12 isotope
(6.02 × 1023 mol–1).
A substance that is broken down naturally in the environment by other living organisms.
A polymer that breaks down completely into carbon dioxide and water.
A diagram showing the distribution of energies of the molecules at a particular temperature.
Bond dissociation enthalpy
The enthalpy change that takes place when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species.
A species that is a proton, H+, donor.
A species that is a proton, H+, acceptor.
A system that minimises pH changes on addition of small amounts of an acid or a base.
An organic ion in which a carbon atom has a negative charge.
An organic ion in which a carbon atom has a positive charge.
A substance that increases the rate of a chemical reaction without being used up in the process.
A positively charged ion.
A scale that compares the frequency of an NMR absorption with the frequency of…