Enthalpy change of formation: the energy
transferred when one mole of the
compound is formed from its elements
under standard conditions with all of the
reactants and products in their standard
states
Enthalpy of atomisation: the
enthalpy change when I mole of
gaseous atoms is formed from
the element in its standard state
under standard conditions
Mean bond enthalpy: the enthalpy
change when mole of gaseous
molecules each breaks a covalent bond
to form two free radicals averaged over
a range of compounds.
First ionisation energy: the enthalpy change
when one mole of gaseous atoms is
converted to one mole of gaseous ions each
with a single posistive charge
Second ionisation energy: the enthalpy change
to remove one mole of electrons from one
mole of gaseous +1 ions to produce a mole of
gaseous +2 ions.
First electron affinity: the enthalpy change when one
mole of gaseous atoms is converted, by gaining a mole of
electrons, to a mole of gaseous ions each with a single
negative charge.
Second electron affinity: the enthalpy change
when one mole of electrons is added to a mole of
gaseous ions each with a single negative charge to
form ions with two negative charges
Lattic formation enthalpy: the enthalpy change
when one mole of solid ionic compound is formed
from its gaseous ions
Enthalpy of hydration: the enthalpy change when water
molecules surround one mole of gaseous ions.
Enthalpy of solution: the enthalpy change when one mole of
solute dissolves completely in sufficient solvent to form a
solution in which the molecules or ions are far enough apart
not to interact with each other.