Lattice energy is the amount of energy released when one mole of an ionic solid is formed from its constituent gaseous ions. This amount of energy released is due to electrostatic force of attraction produced by the `3 D` rearrangement of the constituent ions.

`Na^(+) (g)+Cl^(-) (g)-> Na^(+) Cl^(-) (s) + U`;

where `U` is the lattice energy.

The electrostatic attraction in the ionic bond always follows coulomb's law, which is given by

`F = (q_1q_2)/r^2`

where `r` is the interionic distance and `q_1` & `q_2` are magnitude of charges.

Hence, the magnitude of lattice energy depends on two factors.