M3 definitions

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions. (Units are kJ mol-1)

A measure of the energy required to remove each electron in turn.

Repeating trends in physical and chemical properties across different periods.

The amount of heat released (or absorbed) by a chemical reaction, carried out at constant pressure. Units kJmol-1

A reaction where heat energy is released to the surroundings. (ΔH is negative)

A reaction where heat energy is absorbed from the surroundings. (ΔH is positive)

The enthalpy change of a reaction depends only on the initial and final states and is independent of the route taken.

The average enthalpy change for the breaking of one mole of bonds in gaseous molecules (by homolytic fission).

A solution of known concentration.

Physical states under standard conditions.

• Temperature = 25 oC (298 K) • Pressure of gases = 1 atm (100 kPa) • Concentration of (aq) solutions = 1.00 moldm-3

The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states.

The enthalpy change that accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of H2O(l), under standard conditions.

The enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.

The enthalpy change when one mole of a substance reacts by complete combustion (with oxygen) under standard conditions, all reactants and products being in their standard states.

A reaction in which a more reactive element (halogen) displaces a less reactive element (halogen) from an aqueous solution of its halide ions.

A reaction in which the same element is both oxidised and reduced.