Final answer:
Sulfur (S) has the largest atomic radius while argon (Ar) has the largest ionization energy and sulfur (S) has the highest electron affinity among the two.
Step-by-step explanation:
Considering sulfur (S) and argon (Ar), we can determine which has the largest radius, the largest ionization energy, and the highest electron affinity based on their positions in the periodic table. As we move down a group in the periodic table, the atomic radius increases because additional electron shells are added. However, as we move across a period from left to right, the atomic radius generally decreases due to the increasing nuclear charge pulling electrons closer to the nucleus. Therefore, S has a larger radius than Ar because it is one period above Ar. The ionization energy increases across a period from left to right and decreases down a group. Hence, Ar has the largest ionization energy because it is further to the right in the same period as S. Lastly, electron affinity generally becomes more negative (indicating a greater energy release when an electron is added) across a period until reaching the noble gases, which have a complete valence shell and are not inclined to gain additional electrons. Thus, S has the highest electron affinity because it can gain an electron to achieve a full valence shell, unlike Ar, which already has a full shell.