AQA A-LEVEL CHEMISTRY 7405/3 Paper 3
Relative Atomic Mass - ANSWER The weighted mean mass of an atom of an
element relative to 1/12 of the mass of one atom of carbon-12
First Ionisation energy - ANSWER The energy required to remove an electron from
each atom in one mole of gaseous atoms
Acid - ANSWER A species that is a proton donor
Activation Energy - ANSWER The minimum energy required to start a reaction by
the breaking of bonds
Addition Polymer - ANSWER The process in which unsaturated alkene molecules
ass on to a growing polymer chain one at a time to form a very long saturated
molecule chain
Addition Reaction - ANSWER A reaction in which a reactant is added to an
unsaturated molecule to make a saturated molecule
Adsorption - ANSWER The process that occurs when a gas, liquid or solid is held to
the surface of a solid, or, more rarely, a liquid
Alicyclic Hydrocarbon - ANSWER A hydrocarbon with carbon atoms joined together
in a ring structure
Aliphatic Hydrocarbon - ANSWER A hydrocarbon with carbon atoms joined together
in straight or branched chains
Alkali - ANSWER A type of base that dissolves in water forming hydroxide ions
Alkanes - ANSWER The homologous series with the general formula CnH2n+2
Alkyl Group - ANSWER An alkane with a hydrogen ion removed. Alkyl groups are
often shown as 'R'
Amount of Substance - ANSWER The quantity whose unit is the mole
Anhydrous - ANSWER A substance containing no water molecules
Anion - ANSWER A negatively charged ion
Atom Economy - ANSWER (molecular mass of the desired product/sum of
molecular masses of all products) x100
Atomic Orbital - ANSWER A region within an atom that can hold up to two electrons,
with opposite spins
, Atomic Number - ANSWER The number of protons in the nucleus of an atom
Average Bond Enthalpy - ANSWER 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 substance
Avogadro Constant - ANSWER The number of atoms per mole of the carbon-12
isotope. (6.02 x 10^23)
Base - ANSWER A species that is a proton acceptor
Biodegradable Material - ANSWER A substance that is broken down naturally in the
environment of a living organism
Boltzmann Distribution - ANSWER The distribution of energies of molecules at a
particular temperature, usually shown as a graph.
Bond Enthalpy - ANSWER The enthalpy change hat takes place when breaking by
homolytic fission 1 mol of a given bond in the molecules of a gaseous species
Carbanion - ANSWER An organic ion in which a carbon atom has a negative charge
Carbocation - ANSWER An organic ion in which a carbon ion has a positive charge.
Catalyst - ANSWER A substance that increases the rate of a chemical reaction
without it being used up
Cation - ANSWER A positively charged ion
Cis-Trans Isomerism - ANSWER 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 has the H atom of each carbon on the same side, the trans isomer has the H
atom of each carbon on different sides
Compound - ANSWER A substance formed from two or more chemically bonded
elements in a fixed ratio, usually shown by a chemical formula.
Concentration - ANSWER The amount of solute, in mol, per 1 dm^2
Coordinate Bond - ANSWER A shared pair of electrons which has been provided by
one of the bonding atoms only; also called a dative covalent bond.
Covalent Bond - ANSWER A bond formed by a shared pair of electrons
Cracking - ANSWER The breakdown of long-chained saturated hydrocarbons to
form a mixture of shorter-chained alkanes and alkenes
Curly Arrow - ANSWER A symbol used in reaction mechanisms to show the
movement of an electron pair in the breaking or formation of the molecule
Relative Atomic Mass - ANSWER The weighted mean mass of an atom of an
element relative to 1/12 of the mass of one atom of carbon-12
First Ionisation energy - ANSWER The energy required to remove an electron from
each atom in one mole of gaseous atoms
Acid - ANSWER A species that is a proton donor
Activation Energy - ANSWER The minimum energy required to start a reaction by
the breaking of bonds
Addition Polymer - ANSWER The process in which unsaturated alkene molecules
ass on to a growing polymer chain one at a time to form a very long saturated
molecule chain
Addition Reaction - ANSWER A reaction in which a reactant is added to an
unsaturated molecule to make a saturated molecule
Adsorption - ANSWER The process that occurs when a gas, liquid or solid is held to
the surface of a solid, or, more rarely, a liquid
Alicyclic Hydrocarbon - ANSWER A hydrocarbon with carbon atoms joined together
in a ring structure
Aliphatic Hydrocarbon - ANSWER A hydrocarbon with carbon atoms joined together
in straight or branched chains
Alkali - ANSWER A type of base that dissolves in water forming hydroxide ions
Alkanes - ANSWER The homologous series with the general formula CnH2n+2
Alkyl Group - ANSWER An alkane with a hydrogen ion removed. Alkyl groups are
often shown as 'R'
Amount of Substance - ANSWER The quantity whose unit is the mole
Anhydrous - ANSWER A substance containing no water molecules
Anion - ANSWER A negatively charged ion
Atom Economy - ANSWER (molecular mass of the desired product/sum of
molecular masses of all products) x100
Atomic Orbital - ANSWER A region within an atom that can hold up to two electrons,
with opposite spins
, Atomic Number - ANSWER The number of protons in the nucleus of an atom
Average Bond Enthalpy - ANSWER 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 substance
Avogadro Constant - ANSWER The number of atoms per mole of the carbon-12
isotope. (6.02 x 10^23)
Base - ANSWER A species that is a proton acceptor
Biodegradable Material - ANSWER A substance that is broken down naturally in the
environment of a living organism
Boltzmann Distribution - ANSWER The distribution of energies of molecules at a
particular temperature, usually shown as a graph.
Bond Enthalpy - ANSWER The enthalpy change hat takes place when breaking by
homolytic fission 1 mol of a given bond in the molecules of a gaseous species
Carbanion - ANSWER An organic ion in which a carbon atom has a negative charge
Carbocation - ANSWER An organic ion in which a carbon ion has a positive charge.
Catalyst - ANSWER A substance that increases the rate of a chemical reaction
without it being used up
Cation - ANSWER A positively charged ion
Cis-Trans Isomerism - ANSWER 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 has the H atom of each carbon on the same side, the trans isomer has the H
atom of each carbon on different sides
Compound - ANSWER A substance formed from two or more chemically bonded
elements in a fixed ratio, usually shown by a chemical formula.
Concentration - ANSWER The amount of solute, in mol, per 1 dm^2
Coordinate Bond - ANSWER A shared pair of electrons which has been provided by
one of the bonding atoms only; also called a dative covalent bond.
Covalent Bond - ANSWER A bond formed by a shared pair of electrons
Cracking - ANSWER The breakdown of long-chained saturated hydrocarbons to
form a mixture of shorter-chained alkanes and alkenes
Curly Arrow - ANSWER A symbol used in reaction mechanisms to show the
movement of an electron pair in the breaking or formation of the molecule
