Na+ and Al3+ are isoelectronic but ionic radius Al3+ is less than that of Na+. — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Step 1: Recall the atomic numbers of the elements belonging to Group 16 (the oxygen family/chalcogens). Step 2: The first element is Oxygen with Z=8. Add magic numbers to find subsequent group members: 8 + 8 = 16 (Sulfur); 16 + 18 = 34 (Selenium); 34 + 18 = 52 (Tellurium). Step 3: Comparing the sets of atomic numbers, the set containing 8, 16, 34, 52 corresponds exactly to Group 16.