AQA A LEVEL Chemistry
Relative atomic mass - Answer-The average mass of an atom of an element, relative to 1/12th of the
mass of an atom of Carbon-12
Relative molecular mass - Answer-Average mass of a molecule compared to 1/12th of the mass of a
carbon-12 atom
The Avogradro constant - Answer-the number of particles in a mole
ideal gas equation - Answer-pV = nRT
empirical formula - Answer-the simplest whole number ratio of atoms of each element in a compound
percentage atom economy - Answer-(Mass of desired product/total mass of reactants) x 100
ionic bonding - Answer-the electrostatic attraction between oppositely charged ions in a lattice
covalent bond - Answer-a shared pair of electrons between non-metal elements
co-ordinate bond - Answer-a shared pair of electrons where both electrons are supplied by one atom
repulsion in shapes of molecules - Answer-Lone pair-lone pair > lone pair-bonding pair > bonding pair-
bonding pair
, electronegativity - Answer-the power of an atom to attract the pair of electrons in a covalent bond
hess' law - Answer-Total enthalpy change for a reaction is independent of the route chosen
mean bond enthalpy - Answer-The energy required to break a covalent bond into gaseous atoms
averaged over different molecules
Bonds broken - bonds made
activation energy - Answer-The minimum amount of energy needed to start a chemical reaction
catalyst - Answer-A substance that increases the rate of a chemical reaction without being changed by
providing an alternative reaction pathway by lowering activation energy
Le Chatelier's principle - Answer-When a system in dynamic equilibrium is subjected to change, the
position of equilibrium will shift to oppose the change.
oxidising agents - Answer-electron acceptors
reducing agents - Answer-electron donors
Enthalpy of formation - Answer-Enthalpy change when one mole of a compound is formed from its
constituent elements under standard conditions in their standard states
Enthalpy of atomization - Answer-The energy required to produce one mole of gaseous atoms from an
element in its standard state
Relative atomic mass - Answer-The average mass of an atom of an element, relative to 1/12th of the
mass of an atom of Carbon-12
Relative molecular mass - Answer-Average mass of a molecule compared to 1/12th of the mass of a
carbon-12 atom
The Avogradro constant - Answer-the number of particles in a mole
ideal gas equation - Answer-pV = nRT
empirical formula - Answer-the simplest whole number ratio of atoms of each element in a compound
percentage atom economy - Answer-(Mass of desired product/total mass of reactants) x 100
ionic bonding - Answer-the electrostatic attraction between oppositely charged ions in a lattice
covalent bond - Answer-a shared pair of electrons between non-metal elements
co-ordinate bond - Answer-a shared pair of electrons where both electrons are supplied by one atom
repulsion in shapes of molecules - Answer-Lone pair-lone pair > lone pair-bonding pair > bonding pair-
bonding pair
, electronegativity - Answer-the power of an atom to attract the pair of electrons in a covalent bond
hess' law - Answer-Total enthalpy change for a reaction is independent of the route chosen
mean bond enthalpy - Answer-The energy required to break a covalent bond into gaseous atoms
averaged over different molecules
Bonds broken - bonds made
activation energy - Answer-The minimum amount of energy needed to start a chemical reaction
catalyst - Answer-A substance that increases the rate of a chemical reaction without being changed by
providing an alternative reaction pathway by lowering activation energy
Le Chatelier's principle - Answer-When a system in dynamic equilibrium is subjected to change, the
position of equilibrium will shift to oppose the change.
oxidising agents - Answer-electron acceptors
reducing agents - Answer-electron donors
Enthalpy of formation - Answer-Enthalpy change when one mole of a compound is formed from its
constituent elements under standard conditions in their standard states
Enthalpy of atomization - Answer-The energy required to produce one mole of gaseous atoms from an
element in its standard state
