What best accounts for the periodic trends seen in ionization energy?

The Ionization energy relies on the atomic size, in light of the fact that with increment in size, the separation among core and valence electrons increments and subsequently attraction force among core and valence electron diminishes.

Ionization energy is the energy required to expel an electron from an impartial atom in its gaseous stage. The lower this vitality is, the more promptly the molecule turns into a cation. Consequently, the higher this energy is, the more impossible it is that the molecule turns into a cation.

By and large, components on the right side of the periodic table have a higher ionization vitality in light of the fact that their valence shell is almost filled.
Components on the left half of the periodic table have low ionization energies as a result of their readiness to lose electrons and become cations.
Another factor that influences ionization vitality is electron protecting. Electron protecting portrays the capacity of a molecule's internal electrons to shield its decidedly charged core from its valence electrons.
When moving to one side of a period, the quantity of electrons increments and the quality of protecting increments.
Accordingly, it is simpler for valence shell electrons to ionize, and in this manner the ionization vitality diminishes down a gathering. Electron protecting is otherwise called screening.
The ionization energy of the components inside a period for the most part increments from left to right. This is because of valence shell security.
The ionization energy of the components inside a gathering by and large diminishes through and through. This is because of electron protecting.
The noble gases have extremely high ionization energies in light of their full valence shells as demonstrated in the chart. Note that helium has the most noteworthy ionization vitality of the considerable number of components.