module 3

• Second Ionisation Energy: The energy required to remove one electron from each 1+ ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions
• Successive Ionisation Energy: A measure of the energy required to remove each electron in turn
• Enthalpy change ΔH: The amount of heat released (or absorbed) by a chemical reaction, carried out at constant pressure, units = kJ mol-1
• Standard enthalpy change of reaction, ΔrHθ: The enthalpy change that accompanies a reaction in molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states
• Hess’ Law: The enthalpy change of a reaction depends only on the initial and final states and is independent of the route taken
• Periodicity: The repeating trends in physical and chemical properties (1) Elements are arranged by:

  – Increasing atomic (proton) number (1)

  – In groups with similar chemical properties (1)

  s/p/d Elements: Example: S-block element - A s-block element has its highest energy electron in a s subshell
• First Ionisation Energy: The energy required to remove one electron from each atom (1) in one mole of gaseous atoms to form one mole of gaseous 1+ ions (1)
• Exothermic Reaction: A reaction where heat energy is released to the surroundings (ΔH is negative) (1)

  Endothermic Reaction: A reaction where heat energy is absorbed from the surroundings (ΔH is positive) (1)
• Average bond enthalpy, ΔEHθ: The average enthalpy change for the breaking of 1 mole of bonds in gaseous molecules (by homolytic fission)
• Standard Conditions: are Temperature = 25oC (298K), Pressure 1 atm (100 kPa) and all solutions must have a concentration = 1.00 mol dm-3 (1)
• Standard enthalpy change of neutralisation, ΔneutHθ: The enthalpy change that accompanies the formation of one mole of H2O(l) from neutralisation, under standard conditions
• Standard enthalpy change of formation, ΔfHθ: The enthalpy change when one mole of a compound is formed from its elements in their standard states under standard conditions
• Standard enthalpy change of combustion, ΔcHθ: The enthalpy change for complete combustion of one mole of a substance under standard conditions, all reactants and products being in their standard states
• Rate of Reaction: The change in concentration of a reactant or a product per unit time
• Activation Energy: The minimum energy required to start a reaction by breaking bonds
• Heterogeneous catalysis: Catalysis of a reaction in which the catalyst has a different physical state from the reactants (1)

  Homogeneous catalysis: Catalysis of a reaction in which the catalyst and the reactants are in the same physical state (1)
• Dynamic Equilibrium: Exists in a closed system (1) when the rate of the forward reaction is equal to the rate of the reverse reaction (1) and the concentrations of reactants and products do not change (1)
• Le Chatelier’s principle: When a system in dynamic equilibrium is subjected to change, the equilibrium position will shift to minimise the change (1)