Which of the following atoms has the highest ionization energy?

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

Answer: (C)

Verified step by step guidance

1. Recall 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) and decreases down a group (top to bottom) in the periodic table.
2. Identify the positions of the given elements in the periodic table: Li (Lithium) is in period 2, group 1; Na (Sodium) is in period 3, group 1; K (Potassium) is in period 4, group 1; Ne (Neon) is in period 2, group 18 (a noble gas).
3. Understand that noble gases like Neon 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 by considering both the group and period trends: elements in group 1 have lower ionization energies compared to noble gases in the same or nearby periods.
5. Conclude that Neon (Ne), being a noble gas with a full outer shell and located in period 2, will have the highest ionization energy among the given options.