Homologous Series
A series of organic molecules which contain the same functional group where each successive member differs by a -CH2 group.
Functional Group
A group of atoms responsible for the chemical reactions of a compound.
General Formula
The simplest algebraic formula of a homologous series.
Empirical Formula
The simplest whole number ratio of atoms of each element in a molecule.
Molecular Formula
The actual number of atoms of each element in a molecule.
Structural Formula
Shows how atoms are bonded together in a molecule (minimum detail).
Displayed Formula
Shows all covalent bonds and all atoms present in a molecule.
Structural Isomerism
Where molecules have the same molecular formula but a different structural formula.
Stereoisomerism
Molecules that have the same molecular and structural formula but a different arrangement of atoms in space.
E/Z isomerism
A type of stereoisomerism due to restricted rotation about a C=C double bond. Two different groups must be attached to each carbon atom in the C=C group.
Hydrocarbon
A compound of hydrogen and carbon only.
Saturated hydrocarbon
Compounds containing only single C-C bonds.
Unsaturated hydrocarbons
Compounds containing one or more double C=C bonds.
Homolytic Fission
When a covalent bond breaks, each atom retains one of the bonding pair of electrons (forming radicals).
Heterolytic Fission
When a covalent bond breaks, one atom takes both the bonding electrons in the bonding pair (to form a positive and a negative ion).
Nucleophile
A species which can donate a pair of electrons - (it is attracted to areas of relative positive charge).
Electrophile
A species which can accept a pair of electrons - (it is attracted to areas of relative negative charge).
Free Radical
An atom or group of atoms with an unpaired electrons.
Addition polymerisation
Where small unsaturated molecules (monomers) join together to form a long molecular chain.
Curly Arrow
Indicates the movement of an electron pair to show either breaking or formation of a covalent bond.
Reflux
A continuous cycle of evaporation and condensation used to prevent the escape of volatile components.
Volatility
How easily a substance evaporates - a highly volatile substance evaporates easily.
Fractional Distillation
The separation of components from a mixture using their different boiling points.