ENERGETICS AS/A2 KEYWORDS

Keyword	Definition
Hess's Law	The enthalpy change for a reaction regardless of the route taken to get from reactants to products (and vice versa.)
Temperature	The kinetic energy of particles in a system. The kinetic energy that any one particle could have.
Heat	The total energy of a given amount of substance.
Standard Conditions	101,000 Pa and 298K
Mean Bond Enthalpy	The energy required to break/overcome 1 mole of gaseous covalent bonds - averaged across many other (different) compounds containing the same bond.
1st Ionisation Enthalpy	The heat energy required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous 1+ cations.
2nd Ionisation Enthalpy	The heat energy required to remove 1 mole of electrons from 1 mole of gaseous 1+ cations to form 1 mole of gaseous 2+ cations.
1st Electron Affinity	The enthalpy change when 1 mole of atoms gains 1 mole of electrons to form 1 mole of gaseous 1- anions.
2nd Electron Affinity	The enthalpy change when 1 mole of 1- anions gains 1 mole of electrons to form 1 mole of gaseous 2- anions.
Enthalpy Change	The heat energy change measured at a constant pressure.
Enthalpy of Formation	The heat energy change when 1 mole of a compound is formed from its constituent elements where both the reactants and products are in their standard states.
Enthalpy of Combustion	The heat energy change when 1 mole of a compound completely reacts with oxygen and all products and reactants are in their standard states.
Enthalpy of Atomisation *	The enthalpy change when an element in its standard state is transformed into one mole of gaseous atoms.
Lattice Enthalpy of Formation *	The enthalpy change when 1 mole of a solid ionic compound is formed from its constituent ions in the gas phase.
Lattice Enthalpy of Dissociation	The enthalpy change when 1 mole of an ionic solid compound dissociates/broken up into its constituent ions in the gas phase.
Enthalpy of Hydration	The enthalpy change when 1 mole of aqueous ions are formed from the same ions in the gas phase.
Enthalpy of Solution	The enthalpy change when 1 mole of an ionic solid compound completely dissolves in a large enough amount of water such that its dissociated/dissolved ions are well spread out/separated in the solution - i.e. they do not interact.