Question

each of these atoms are in group 2. which atom will have the smallest atomic radius?
magnesium, mg (3 energy levels)
barium, ba (6 energy levels)
beryllium, be (2 energy levels)

Explanation:

Step1: Understand atomic radius trend

Atomic radius increases down a group as the number of energy levels increases.

Step2: Compare energy levels

Beryllium (Be) has 2 energy levels, magnesium (Mg) has 3, and barium (Ba) has 6.

Answer:

Beryllium, Be (2 energy levels)