text: This lattice calculation is complex. To make gaseous ions from elements it is necessary to atomise the elements (turn each into gaseous atoms) and then to ionise the atoms. If the element is normally a molecule then we first have to consider its bond dissociation enthalpy (see also bond energy). The energy required to remove one or more electrons to make a cation is a sum of successive ionization energies; for example, the energy needed to form Mg2+ is the ionization energy required to remove the first electron from Mg, plus the ionization energy required to remove the second electron from Mg+. Electron affinity is defined as the amount of energy released when an electron is added to a neutral atom or molecule in the gaseous state to form a negative ion.
  The Born–Haber cycle applies only to fully ionic solids such as certain alkali halides. Most compounds include covalent and ionic contributions to chemical bonding and to the lattice energy, which is represented by an extended Born–Haber thermodynamic cycle. The extended Born–Haber cycle can be used to estimate the polarity and the atomic charges of polar compounds.
  Examples
  Formation of LiF
  The enthalpy of formation of lithium fluoride (LiF) from its elements in their standard states (Li(s) and F2(g)) is modeled in five steps in the diagram:
  Atomization enthalpy of lithium
  Ionization enthalpy of lithium
  Atomization enthalpy of fluorine
  Electron affinity of fluorine
  Lattice enthalpy
  The sum of the energies for each step of the process must equal the enthalpy of formation of lithium fluoride, .
  is the enthalpy of sublimation for metal atoms (lithium)