Answer: effective nuclear charge increases as electron shielding remains constant. ... The increased distance weakens the nuclear attraction to the outer-most electron, and is easier to remove (requires less energy).
Explanation:
In general, ionization energy increases across a period and decreases down a group. Across a period, effective nuclear charge increases as electron shielding remains constant. ... The increased distance weakens the nuclear attraction to the outer-most electron, and is easier to remove (requires less energy).
