Which of the following elements has the largest ionization energy?

• A. Ne (neon)
• B. K (potassium)
• C. Na (sodium)
• D. Li (lithium)

Answer: (A)

Verified step by step guidance

1. Understand that ionization energy is the energy required to remove an electron from a gaseous atom or ion. It generally increases across a period (left to right) in the periodic table and decreases down a group (top to bottom).
2. Identify the positions of the given elements in the periodic table: Li, Na, and K are all alkali metals in Group 1, with Li at the top, Na below it, and K further down. Ne (neon) is a noble gas in Group 18, located at the far right of the same period as Na.
3. Recall that noble gases have very high ionization energies because they have a full valence shell, making them very stable and less willing to lose electrons.
4. Compare the ionization energies based on their positions: since ionization energy increases across a period and decreases down a group, Ne will have a higher ionization energy than Li, Na, and K.
5. Conclude that among the given elements, Ne has the largest ionization energy due to its full valence shell and position on the periodic table.