AQA A Level Chemistry Definitions
Questions with Complete Solutions
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
E/Z Isomerism A type of stereoisomerism in which different groups attached to each carbon
of a C=C double bond may be arranged differently in space because of the restricted rotation of
the C=C bond
Electron Configuration The arrangement of electrons in an atom
Electronegativity A measure of the attraction of a bonded atom for the pair of electrons in a
covalent bond
Electron Shielding The repulsion between electrons in different inner shells. Shielding
reduces the net attractive force from the positive nucleus on the outer shell of electrons
, Electrophile An atom (or group of atoms) that is attracted to an electron-rich centre or atom,
where it accepts a pair of electrons to form a new covalent bond
Electrophilic Addition A type of addition reaction in which an electrophile is attracted to an
electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond
Elimination Reaction The removal of a molecule from a saturated molecule to make an
unsaturated molecule
Empirical Formula The simplest whole-number ratio of atoms of each element present in a
compound
Endothermic Reaction A reaction in which the enthalpy of the products is greater than the
enthalpy of the reactants, resulting in heat being taken in from the surroundings
Enthalpy The heat content that is stored in a chemical system
Questions with Complete Solutions
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
E/Z Isomerism A type of stereoisomerism in which different groups attached to each carbon
of a C=C double bond may be arranged differently in space because of the restricted rotation of
the C=C bond
Electron Configuration The arrangement of electrons in an atom
Electronegativity A measure of the attraction of a bonded atom for the pair of electrons in a
covalent bond
Electron Shielding The repulsion between electrons in different inner shells. Shielding
reduces the net attractive force from the positive nucleus on the outer shell of electrons
, Electrophile An atom (or group of atoms) that is attracted to an electron-rich centre or atom,
where it accepts a pair of electrons to form a new covalent bond
Electrophilic Addition A type of addition reaction in which an electrophile is attracted to an
electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond
Elimination Reaction The removal of a molecule from a saturated molecule to make an
unsaturated molecule
Empirical Formula The simplest whole-number ratio of atoms of each element present in a
compound
Endothermic Reaction A reaction in which the enthalpy of the products is greater than the
enthalpy of the reactants, resulting in heat being taken in from the surroundings
Enthalpy The heat content that is stored in a chemical system
