Which of the following best describes the effect of a larger shielding effect on the ionization energy of an atom?

• A. It increases the ionization energy.
• B. It causes the ionization energy to fluctuate unpredictably.
• C. It has no effect on the ionization energy.
• D. It decreases the ionization energy.

Answer: (D)

Verified step by step guidance

1. Understand that ionization energy is the energy required to remove an electron from an atom in its gaseous state.
2. Recognize that the shielding effect occurs when inner electrons reduce the effective nuclear charge felt by the outer (valence) electrons.
3. Know that a larger shielding effect means the outer electrons experience less attraction from the nucleus because inner electrons block some of the positive charge.
4. Since the outer electrons are held less tightly due to increased shielding, it requires less energy to remove one, meaning the ionization energy decreases.
5. Therefore, a larger shielding effect leads to a decrease in ionization energy, as the outer electrons are easier to remove.