Which of the following atoms would you expect to have the largest atomic radius?

• A. Li
• B. K
• C. Rb
• D. Na

Answer: (B)

Verified step by step guidance

1. Understand that atomic radius generally increases as you move down a group (column) in the periodic table because additional electron shells are added, increasing the size of the electron cloud.
2. Identify the group to which the given elements belong. Li, Na, K, and Rb are all in Group 1 (alkali metals), so their atomic radius trend will follow the group trend.
3. Compare the positions of the elements in the periodic table: Li is in period 2, Na in period 3, K in period 4, and Rb in period 5.
4. Since atomic radius increases down a group, the element with the largest atomic radius will be the one in the lowest period (highest period number) among the options.
5. Conclude that Rb, being in period 5, should have the largest atomic radius, followed by K, Na, and Li in decreasing order.