Question

Why does ionization energy increase across a period

Answer 1

electrons

Step-by-step explanation:

more electrons hold the valence electrons more tightly to the nucleus

valence electrons are the electrons on the outer most ring in the electron cloud

Answer 2

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).

Step-by-step 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).