AQA A Level Chemistry Definitions /
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Terms in this set (101)
Relative Atomic Mass 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 The energy required to remove an electron from each atom in
one mole of gaseous atoms
Acid A species that is a proton donor
Activation Energy The minimum energy required to start a reaction by the
breaking of bonds
The process in which unsaturated alkene molecules ass
Addition Polymer on to a growing polymer chain one at a time to form a
very long saturated molecule chain
, Addition Reaction A reaction in which a reactant is added to an unsaturated
molecule to make a saturated molecule
Adsorption 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 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
Alkali A type of base that dissolves in water forming hydroxide ions
Alkanes The homologous series with the general formula
CnH2n+2
Alkyl Group An alkane with a hydrogen ion removed. Alkyl groups are often
shown as 'R'
Amount of Substance The quantity whose unit is the mole
Anhydrous A substance containing no water molecules
Anion A negatively charged ion
Atom Economy (molecular mass of the desired product/sum of molecular
masses of all products) x100
Atomic Orbital A region within an atom that can hold up to two electrons, with
opposite spins
Atomic Number The number of protons in the nucleus of an atom
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 substance
Avogadro Constant The number of atoms per mole of the carbon-12 isotope.
(6.02 x 10^23)
Base A species that is a proton acceptor
Actual Exam Questions Bank with Definitive
Explanations of Answers / Newest 2025/2026.
Practice questions for this set
Learn
Studied terms
Nice work, you're crushing it
Continue studying in Learn
Terms in this set (101)
Relative Atomic Mass 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 The energy required to remove an electron from each atom in
one mole of gaseous atoms
Acid A species that is a proton donor
Activation Energy The minimum energy required to start a reaction by the
breaking of bonds
The process in which unsaturated alkene molecules ass
Addition Polymer on to a growing polymer chain one at a time to form a
very long saturated molecule chain
, Addition Reaction A reaction in which a reactant is added to an unsaturated
molecule to make a saturated molecule
Adsorption 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 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
Alkali A type of base that dissolves in water forming hydroxide ions
Alkanes The homologous series with the general formula
CnH2n+2
Alkyl Group An alkane with a hydrogen ion removed. Alkyl groups are often
shown as 'R'
Amount of Substance The quantity whose unit is the mole
Anhydrous A substance containing no water molecules
Anion A negatively charged ion
Atom Economy (molecular mass of the desired product/sum of molecular
masses of all products) x100
Atomic Orbital A region within an atom that can hold up to two electrons, with
opposite spins
Atomic Number The number of protons in the nucleus of an atom
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 substance
Avogadro Constant The number of atoms per mole of the carbon-12 isotope.
(6.02 x 10^23)
Base A species that is a proton acceptor
