| isotope | atoms of the same element with different numbers of neutrons and different masses |
| relative isotopic mass | mass compared with 1/12th mass of carbon 12 |
| relative atomic mass | weighted mean mass compared with 1/12th mass of carbon 12 |
| empirical formula | simplest whole number ratio of atoms of each element present in a compound |
| molecular formula | number and type of atoms of each element in a molecule |
| ionic bonding | electrostatic attraction between positive and negative ions |
| covalent | strong electro station attraction between a shared pair of electrons and nuclei of bonded atoms |
| electronegativity | ability of an atom to attract the bonding electrons in a covalent bond |
| first ionisation energy | removal of 1 ‘ol of electrons from 1 mol of gaseous atoms |
| metallic bonding | strong electro station attraction between cations and delocalised electrons |
| disproportionation | oxidation and reduction of the same element |
| standard conditions and standard states | physical states under standard conditions |
| enthalpy change of formation | one mol of a compound formed from its elements |
| enthalpy change of combustion | complete combustion of 1 mol of a substance |
| enthalpy change of neutralisation | formation of 1 mol of water from neutralisation |
| average bond enthalpy | breaking of 1 mol of bonds in gaseous molecules |
| general formula | simplest algebraic formula of a member of a homologous series |
| structural formula | minimal detail that shows arrangement of atoms in a molecule |
| skeletal formula | the simplified organic formula shown by removing hydrogen groups from alkyl chains |
| homologous series | a series of organic compounds having the same functional group but with each successive member by differing by ch2 |
| functional group | a group of atoms responsible for the characteristic reactions of a compound |
| aliphatic | compound containing carbon and hydrogen joined together in straight branched chains or non aromatic rings |
| alicyclics | an aliphatic compound arranged in non aromatic rings or without side chains |
| saturated | single carbon carbon bonds |
| structural isomers | compounds with the same molecular formula but different structural formula |
| homolytic fission | each bonding atom receiving ice electron from the bonded pair forming two radicals |
| heterolytic fission | one bonding atom receiving both electrons from the bonded pair |
| radical | species with an unpaired electron |
| sigma bonds | overlap of orbitals directly between the bonding atoms |
| stereoisomers | compounds with the same structural formula but with a different arrangement in space |
| electrophile | electron pair acceptiorb |
| nucleophile | an electron pair donor |
