Name the factors which affect the ionization energy of an element
Answers
There are basically three:
Nuclear charge: The larger the atomic number, the higher the amount of charge at the nuclei, and therefore the strongest the attraction that it exerts into its electrons. This therefore implies a higher ionization energy.
The number of energy levels filled: Ionization will always occur from the highest in energy atomic orbital occupied, that is the most external. Therefore, the higher the number of energy cores filled, the lowest the ionization energy.
Electronic repulsion: The highest the electronic charge of an atom, the highest the electronic repulsion it will present and therefore it will be more favored to release one of those electrons to reduce the electronic density.
There are other effects to take into account in specifically cases (full or semi-full valency core configurations), but in general these three are the main effects with which one can explain ionization energy differences between all elements in the periodic table.