Chemistry

Question Analysis
This question evaluates the student's ability to compare and arrange elements based on their atomic radii and to understand the underlying reasons for the differences.

Key Concept Explanation
The atomic radius is influenced by the nuclear charge and electron shielding. Chlorine has a higher nuclear charge and similar electron shielding compared to sulfur, making its atomic radius smaller. Sulfur has fewer protons and less nuclear charge, resulting in a larger atomic radius. Argon, being a noble gas, is measured by van der Waals radius, which is larger due to weaker intermolecular forces.

Step-by-step Solution
1. Identify the elements: Sulfur (S), Chlorine (Cl), and Argon (Ar).
2. Compare the nuclear charges: Cl (17 protons) > S (16 protons) > Ar (18 protons, but measured by van der Waals radius).
3. Consider the electron shielding: S and Cl have similar electron configurations, but Cl has a higher nuclear charge, pulling the electrons closer.
4. Note that Ar, being a noble gas, is measured by van der Waals radius, which is larger due t...