What happens to the ionization energy of elements as you move from left to right across a period in the periodic table?

• A. Ionization energy remains constant.
• B. Ionization energy increases.
• C. Ionization energy decreases.
• D. Ionization energy first increases, then decreases.

Answer: (B)

Verified step by step guidance

1. Understand that ionization energy is the energy required to remove an electron from a gaseous atom or ion.
2. Recall that as you move from left to right across a period in the periodic table, the number of protons in the nucleus increases, which increases the nuclear charge.
3. Recognize that the increased nuclear charge pulls the electrons closer to the nucleus, making it harder to remove an electron.
4. Note that the shielding effect remains relatively constant across a period because electrons are added to the same principal energy level, so the increased nuclear charge is not significantly offset.
5. Conclude that because of the stronger attraction between the nucleus and the electrons, the ionization energy generally increases as you move from left to right across a period.