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

• A. Na (Sodium)
• B. K (Potassium)
• C. Ne (Neon)
• D. Li (Lithium)

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) and decreases down a group (top to bottom).
3. Identify the positions of the elements: Na (Sodium), K (Potassium), and Li (Lithium) are all in Group 1 (alkali metals), while Ne (Neon) is a noble gas in Group 18, at the end of the same period as Na.
4. Since Ne is a noble gas with a full valence shell, it has a much higher ionization energy compared to alkali metals, which have only one valence electron and tend to lose it easily.
5. Conclude that among the given elements, Ne (Neon) has the highest first ionization energy due to its stable electron configuration and position on the periodic table.