DEFINITIONS Flashcards
Activation Energy
the minimum energy required to start a reaction by the breaking of bonds
Addition polymer
a very long molecular chain, formed by repeated addition reactions of many unsaturated alkene molecules (monomers)
Addition Polymerisation
the process in which unsaturated alkene molecule (monomers) add on to a growing polymer chain one at a time to form a very long saturated molecular chain (the addition polymer)
Addition reaction
a reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule
Alicyclic hydrocarbon
a hydrocarbon with carbon atoms joined together in a ring structure
Aliphatic hydrocarbon
a hydrocarbon with carbon atoms joined together in straight or branched chains
Alkyl group
an alkane with a hydrogen atom removed, e.g. CH3, C2H5; alkyl groups are often shown as R
Anhydrous
a substance containing no water molecules
Atom economy
(molecular mass of the desired product/ sum of molecular masses of all products) x100
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
Bond enthalpy
the enthalpy change that takes place when breaking by homolytic fission 1 mole of a given bond in the molecules of a gaseous species
Catalyst
A substance that increases the rate of reaction by lowering the activation energy
Cis-trans isomerism
a special type of E/Z isomerism in which there is a non-hydrogen group and a hydrogen on each C of a C=C double bond: the cis isomer (Z isomer) has the H atoms on each carbon on the same side; the Trans isomer has the H atoms on opposite sides
Compound
a substance formed from two or more chemically bonded elements in a fixed ratio, usually shown by a chemical formula
Covalent bond
a bond formed by a shared pair of electrons
Cracking
the breaking down of long-chained saturated hydrocarbons to form a mixture of shorter-chained alkanes and alkenes
Dative covalent bond
a shared pair of electrons which has been provided by one of the bonding atoms only; also called a coordinate bond
Dehydration
an elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule
Delocalised electrons
electrons that are shared between more than two atoms
Displacement reaction
a reaction in which a more reactive element displaces a less reactive element from an aqueous solution of the latter’s ions
Displayed formula
a formula showing the relative positioning of all the atoms in a molecule and the bonds between them
Disproportionation
the oxidation and reduction of the same element in a redox reaction
Dynamic equilibrium
the equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction
