Which of the following elements has the highest first ionization energy?

• A. Na (Sodium)
• B. Mg (Magnesium)
• C. Ne (Neon)
• D. Al (Aluminum)

Answer: (C)

Verified step by step guidance

1. Understand that the first ionization energy is the energy required to remove one electron from a neutral atom in the gaseous state.
2. Recall the general trend in the periodic table: ionization energy increases across a period (left to right) due to increasing nuclear charge attracting electrons more strongly.
3. Identify the elements given: Na (Sodium), Mg (Magnesium), Al (Aluminum), and Ne (Neon), all in the same period (Period 3).
4. Compare their positions: Sodium is group 1, Magnesium group 2, Aluminum group 13, and Neon group 18 (noble gas). Since Neon is a noble gas with a full valence shell, it has a much higher ionization energy than the others.
5. Conclude that Neon has the highest first ionization energy among the listed elements because of its stable electron configuration and strong effective nuclear charge.