22.1 Lattice enthalpy

• Lattice enthalpy is the measure of ionic bond strength in a giant ionic lattice
• Lattice enthalpy is the enthalpy change that accompanies the formation of 1 mole of an ionic compound from its gaseous ions in standard conditions
• Lattice enthalpy is calculated using a Born-Haber cycle
• The standard enthalpy change of atomisation is the enthalpy change for the formation of one mole of gaseous atoms from the element in its standard state under standard conditions
• First ionisation energy is the enthalpy change for the removal of one electron from each atom in one mole of gaseous atoms to form one mole of 1+ gaseous ions
• First electron affinity is the enthalpy change for the addition of one electron to each atom in one mole of gaseous atoms to form one mole of gaseous 1- ions
• Enthalpy change of formation is the enthalpy change for the formation of one mole of a compounds from its elements in their standard states under standard conditions
• In a Born-Haber cycle, energy changes connect elements in their standard states with gaseous atoms, gaseous ions and the solid ionic lattice
• Some Born-Haber Cycles require first and second ionisation energies
• Some Born-Haber Cycles require first and second electron affinities
• Second electron affinity is endothermic

  • electron is already gained which repels the negative electron
  • energy is needed to force the negatively charged electron onto the negative ion