Practice!

Sample Problem

Identify the ion out of the pair that has the smaller radius (enter 1 if the ion is in column 1 or 2 if the ion is in column 2)

1

2

Smaller radius

S-

S2-

 

F-

Cl-

 

O2-

P3-

 

 

Solution

More negatively charged anions are larger because they have gained additional electrons. The atomic trends for anions in the same group still apply, so ions higher up along a group are smaller. Hence, S-, F-, and O2- are smaller in their respective pair