Which atom forms an ion with a radius larger than the atomic radius?

NY Regents Chemistry Exam August 2023

13. Which atom forms an ion with a radius larger than the atomic radius?

(1) calcium atom

(2) oxygen atom

(3) lead atom

(4) tin atom

Solution: An atom that gains electrons will have a larger ionic radius than the atomic radius. We can look at the Periodic Table on the Reference Table to find the oxidation numbers (top right corner) for the elements listed.

Ca = +2 (loses 2 electrons)

O = -2 (gains 2 electrons)

Pb = +2 (loses 2 electrons)

Sn = +2 (loses 2 electrons)

Oxygen gains two electrons to become O^2- and is the correct answer (2)

Prepare for the Chemistry Regents Exam: HERE 

Contact us for Chemistry Tutoring: HERE