What happens to the number of protons in the nucleus as you go across a period? Use this to explain the trends in atomic radius and ionization energy across a period.

The number of protons increase as you go across a period.

Atomic radius decreases as we go across the period as the number of protons increase and due to that the charge increases which leads to the decrease in size of atomic radius. Similarly due to increase in charge, removal of electron becomes harder thus the more energy is required ti detach the electron which leads to increase in ionization energy.