Let x be a hypothetical element. Which of the following would have the largest atomic radius?

• A. x in Group 17, Period 2
• B. x in Group 2, Period 3
• C. x in Group 16, Period 4
• D. x in Group 1, Period 5

Answer: (D)

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, making the atom larger.
2. Recognize that atomic radius generally decreases as you move from left to right across a period (row) due to increasing nuclear charge pulling electrons closer to the nucleus.
3. Analyze each option by identifying its group and period to estimate relative atomic size: Group 17, Period 2; Group 2, Period 3; Group 16, Period 4; and Group 1, Period 5.
4. Compare the periods first: Period 5 elements have more electron shells than Periods 2, 3, and 4, so they tend to have larger atomic radii.
5. Consider the group positions: Group 1 elements have the smallest effective nuclear charge in their period, leading to less pull on the outer electrons and thus a larger atomic radius compared to elements in Groups 2, 16, or 17 of the same or lower periods.