AP Chemistry Question 29: Answer and Explanation

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Question: 29

6. The first ionization energy for a neutral atom of chlorine is 1.25 MJ/mol and the first ionization energy for a neutral atom of argon is 1.52 MJ/mol. How would the first ionization energy value for a neutral atom of potassum compare to those values?

  • A. It would be greater than both because potassium carries a greater nuclear charge then either chlorine or argon.
  • B. It would be greater than both because the size of a potassium atom is smaller than an atom of either chlorine or argon.
  • C. It would be less than both because there are more electrons in potassium, meaning they repel each other more effectively and less energy is needed to remove one.
  • D. It would be less than both because a valence electron of potassium is farther from the nucleus than one of either chlorine or argon.

Correct Answer: D

Explanation:

D Potassium's first valence electron is in the fourth energy level, but both chlorine and argon's first valence electron is in the third energy level.