Which of the following species will have the highest ionization energy?

• A. Mg
• B. Al
• C. Na
• D. Ne

Answer: (D)

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) in the periodic table and decreases down a group (top to bottom).
2. Identify the position of each species in the periodic table: Na (sodium) is in Group 1, Period 3; Mg (magnesium) is in Group 2, Period 3; Al (aluminum) is in Group 13, Period 3; Ne (neon) is in Group 18, Period 2.
3. Understand that noble gases like Ne have completely filled valence shells, which makes them very stable and thus have very high ionization energies compared to metals like Na, Mg, and Al.
4. Compare the ionization energies by considering effective nuclear charge and electron configuration: Ne has a full octet and a higher effective nuclear charge experienced by its valence electrons, making it harder to remove an electron.
5. Conclude that among the given species, Ne will have the highest ionization energy because it is a noble gas with a full valence shell and a strong attraction between its nucleus and electrons.