**Lattice Energy (Crystal Energy)**

The lattice energy is the amount of energy evolved when gaseous ions of opposite charges are brought together to form an ionic crystal composed of 1 mole of formula units of a compound.

**OR**

** **Lattice energy is defined as the amount of energ’y required to convert one mole of an ionic solid to its gaseous ions.

The concept of Lattice energ’y was originally developed for rock-salt structured and Sphalerite structure.The sphalerite structure is made up of zinc and sulfur.The compounds like Na-Cl and Zns ,where the ions occupy high symmetry crystal lattice sites.

- Na
^{+}+ Cl^{−}→ Na Cl

##### lattice energy is depend upon

The lattice energ’y is depend upon the strength of the interaction between the particles in the solid and in the geometry of the crystal structure.It is a measure of the stability of an ionic solid. The greater the lattice energ’y,the stronger the bond.

### Lattice energy maybe determined in two different ways:

**By theoretical calculation****By experimental measurement**

The theoretical approach involves the calculation of interaction energies among all the particles in a crystal.The calculation gives a result which is simply represented as follows;

**q+**and

**q-**are the charges on the ions , r+ and r- are the ionic radii.Where B is an small constant of repulsion.

**ionic radii.**