9701 A2 Chemistry - Table of definitions (2022)
Term
Definition
Standard enthalpy of
atomisation (ΔHatm)
The enthalpy change when one mole of gaseous atoms is formed from the elements in their standard states. (Endothermic)
AG
Lattice enthalpy (ΔHlattice)
The energy released when one mole of a solid (ionic) lattice is formed from its constituent gaseous ions under standard
conditions.
Enthalpy change of
solution (ΔHsol)
The enthalpy change when one mole of an ionic solid in sufficient water to form an infinitely dilute solution.
Enthalpy change of
hydration (ΔHhyd)
First electron affinity
Entropy
Activation energy (Ea)
Rate of reaction
Catalyst
Homogeneous
Heterogeneous
Order (reactant)
Overall order
Half life
Rate determining step
The enthalpy change when one mole of a gaseous ion dissolves in sufficient water to form an infinitely dilute solution.
The enthalpy change when one mole of electrons is added to one mole of gaseous atoms to form one mole of 1- gaseous
ions under standard conditions.
The number of possible arrangements of the particles and their energy in a given system.
The minimum energy needed for a collision to be effective
The change in concentration of a substance with respect to time
A reagent that increases the rate of a reaction by providing an alternative pathway/mechanism with lower activation energy.
It is regenerated (not used up) at the end of the reaction
In the same phase/state as the reactants
In a different phase/state to the reactants
The power to which the concentration of a reactant is raised in the rate equation
The sum of the individual orders of each reactant in the rate equation
The time taken for the concentration of a reactant to halve.
The slowest step in the reaction mechanism
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Term
Definition
Equivalence point
(titration)
The point (volume) at which the amount (mol) of acid added is equal to the amount (mol) of alkali (or vice versa)
End point (titration)
AG
The point (volume) at which the indicator changes colour.
Partition coefficient (Kpc)
The ratio of the concentrations of a solute in two immiscible solvents at equilibrium.
Standard electrode/
Reduction potential (Eϴ)
Voltage of an electrode/half-cell relative to the standard hydrogen electrode measured at 298 K, 1 atm pressure using 1 moldm-3
solutions
Standard cell potential
(Eϴcell)
The potential difference between the anode and the cathode measured at 298 K, 1 atm pressure using 1 moldm-3 solutions
Dative covalent (Coordinate) bond
A covalent bond in which both the electrons in the bond are donated by same species.
Transition element (CAIE
definition)
An element that forms at least one stable ion with a partially filled d-subshell/d-orbitals.
Degenerate orbitals
Orbitals at the same energy.
Non-degenerate orbitals
Orbitals at different energies.
Ligand
A species that donates a lone pair of electrons to form a dative covalent/coordinate bond to a central metal atom/ion (to form a
complex)
Complex (ion)
A species that consists of a central metal atom/ion bonded to one or more ligands
Stability constant (Kstab)
The equilibrium constant for the formation of the complex ion in a solvent (from its constituent ions or molecules)
Enantiomers
Two molecules that are non-superimposable mirror images of each other.
Optically active
(substance)
Racemic mixture
The ability (of a substance) to rotate the plane of plane polarised light.
A mixture of equal quantities of two enantiomers
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