Question

Why does ionization potential decreases on moving down the group ?​

Answer 1

Answer:

When moving to the right of a period, the number of electrons increases and the strength of shielding increases. As a result, it is easier for valence shell electrons to ionize, and thus the ionization energy decreases down a group. Electron shielding is also known as screening. This is due to valence shell stability.

Answer 2

Answer:

This is because the size of the atom increases as we move down the group.