Which element in each pair has atoms with a larger atomic radius selenium oxygen?

Answer 1

For the representative elements (main group elements), atomic radius generally decreases from left to right across a period.

Example:

B and Fl: Fl has the smaller atomic radius

Li and Be: Be has the smaller atomic radius

Answer 2

Selenium (115 pm) has a larger atomic radius than oxygen (60 pm).

Answer 3

Sodium has the larger radius.