Question

question 9 of 10
what makes the atomic radius change down a column of the periodic table?

a. the greater number of total electrons, the larger the atomic radius.

b. the more sublevels occupied, the larger the atomic radius.

c. the larger the highest energy level number, the larger the atomic radius.

d. the more valence electrons listed, the larger the atomic radius.

Explanation:

To determine the correct answer, we analyze each option:

• Option A: Total electrons alone don't determine atomic radius. For example, isoelectronic species have different radii due to nuclear charge, so A is incorrect.
• Option B: Sublevels occupied is not the key factor. The number of principal energy levels (shells) is more relevant. So B is incorrect.
• Option C: Down a column (group) in the periodic table, the highest energy level number (principal quantum number, \(n\)) increases. As \(n\) increases, the electrons are in larger orbitals, so the atomic radius increases. This is the correct reason.
• Option D: Valence electrons down a group remain the same (same group has same valence electron configuration), so valence electrons don't cause the radius change down a group. Thus, D is incorrect.

Answer:

C. The larger the highest energy level number, the larger the atomic radius.