Which element has the largest first ionization energy among O, F, Ne, N?

Which element has the largest first ionization energy among O, F, Ne, N?

• A. Oxygen
• B. Neon
• C. Fluorine
• D. Nitrogen

Answer: (B)

First ionization energy is the energy required to remove the outermost electron from a neutral atom. Across a period, this energy tends to increase because the nuclear charge grows while the shielding effect stays similar, pulling the outer electrons closer and making them harder to remove. Neon has the highest energy here because it has a complete valence shell (2s2 2p6), giving it exceptional stability. Removing one electron would disrupt that full shell, which requires a lot more energy than removing an electron from the other elements with only partially filled p subshells. Fluorine, nitrogen, and oxygen all lose an electron more readily than neon because their outer shells are not closed, even though fluorine is highly electronegative. So neon's closed-shell configuration makes its first ionization energy the largest among these elements.

First ionization energy is the energy required to remove the outermost electron from a neutral atom. Across a period, this energy tends to increase because the nuclear charge grows while the shielding effect stays similar, pulling the outer electrons closer and making them harder to remove. Neon has the highest energy here because it has a complete valence shell (2s2 2p6), giving it exceptional stability. Removing one electron would disrupt that full shell, which requires a lot more energy than removing an electron from the other elements with only partially filled p subshells. Fluorine, nitrogen, and oxygen all lose an electron more readily than neon because their outer shells are not closed, even though fluorine is highly electronegative. So neon's closed-shell configuration makes its first ionization energy the largest among these elements.