Why does lattice enthalpy decrease down the group?

Lattice Enthalpy:

1. As we move down the group, the lattice energy decreases.
2. This is due to the fact that with the increase in atomic size, the distance between their nuclei increases.
3. Therefore, decreasing the force of attraction and increasing the inter-electronic repulsion between them.
4. Finally, less lattice energy is released during the process.

Hence, lattice enthalpy decreases down the group.