Question

the atomic radius of aluminum is greater than ______.

a thallium

b gallium

c boron

d none of the above

Explanation:

To determine the atomic radius relationship, we use the periodic table trends. Atomic radius generally increases down a group (as more electron shells are added) and decreases across a period. Boron (B), Aluminum (Al), Gallium (Ga), and Thallium (Tl) are in Group 13. The order down the group is B < Al < Ga < Tl (considering typical trends, though Ga has a slight anomaly, but overall Al's radius is less than Ga and Tl, and greater than B). So Al's atomic radius is greater than Boron's.

Answer:

c. Boron