###### Answer: It is a measure of the strength of the bonds between ions

is an arbitrary lattice vector. Such a model is sensible because crystal ions that form the lattice structure are typically on the order of tens of thousands of times more massive than electrons making it safe to replace them with a fixed potential structure and the macroscopic dimensions of a crystal are typically far greater than a single lattice spacing making edge effects negligible.

Unit cell. Crystal structure is described in terms of the geometry of arrangement of particles in the unit cell. The unit cell is defined as the smallest repeating unit having the full symmetry of the crystal structure. The geometry of the unit cell is defined as a parallelepiped providing six lattice parameters taken as the lengths of the cell edges (a b c) and the angles between them (α …

The Born–Landé equation is a means of calculating the lattice energy of a crystalline ionic compound.In 1918 Max Born and Alfred Landé proposed that the lattice energy could be derived from the electrostatic potential of the ionic lattice and a repulsive potential energy term. = − + − (−) where: N A = Avogadro constant;; M = Madelung constant relating to the geometry of the crystal ;

Perfect crystals. In a crystal the constitutive particles are arranged periodically with translational symmetry forming a lattice .The crystal structure can be described as a Bravais lattice with a group of atoms called the basis placed at every lattice point; that is [ crystal stru…