Lattice Energy A Theoretical Evaluation

Lattice energy is the energy change that accompanies the process in which the isolated gaseous ions of a compound come together to form 1 mol of the ionic solid. For a solid composed of monoatomic, singly charged ions, such as sodium chloride, the lattice 

How can we approach a theoretical evaluation of the lattice energy The simplest starting point is the electrostatic interaction within an ion pair made up of one sodium cation and one chloride anion. Assuming the energy of the isolated gaseous ions is taken to be zero, the potential energy of the ion pair is given by Coulomb s law and is shown in Equation (8.2)  

If we want the interionic distance to be in Angstrom units and the energy to be in kilojoules (kj), the exact relationship for Coulomb s law for one Na Cl ion pair is as given in Equation (8.3)  

First noting that in NaCl, Z = — Z, rearrangement yields Equation (8.5)  

Madelung Constants for Some Common Crystal Structures 

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