Which of the following correctly ranks the atoms Rb, F, Mg, B, and N in order of decreasing atomic radius (largest to smallest)?

• A. Rb > B > Mg > N > F
• B. Mg > Rb > B > N > F
• C. F > N > B > Mg > Rb
• D. Rb > Mg > B > N > F

Answer: (D)

Verified step by step guidance

1. Recall that atomic radius generally increases as you move down a group in the periodic table because additional electron shells are added, making the atom larger.
2. Recall that atomic radius generally decreases as you move from left to right across a period due to increasing nuclear charge pulling electrons closer to the nucleus.
3. Identify the positions of the atoms Rb, Mg, B, N, and F on the periodic table: Rb is in Group 1, Period 5; Mg is in Group 2, Period 3; B, N, and F are in Period 2 with B in Group 13, N in Group 15, and F in Group 17.
4. Use the trends to rank the atoms: since Rb is the furthest down and to the left, it has the largest radius; Mg is next down and left; B, N, and F are in the same period with radius decreasing from B to N to F due to increasing nuclear charge.
5. Combine these observations to write the order of decreasing atomic radius as: \(\mathrm{Rb} > \mathrm{Mg} > \mathrm{B} > \mathrm{N} > \mathrm{F}\).