a) Explain why fluorine has a smaller atomic radius than oxygen. b) Explain why fluorine has a smaller atomic radius than chlorine.

Answer 1

Both F and O are in period 2 meaning they both have 2 shells of electrons. But, F has 9 protons attracting those other electrons wheres O has only 8 protons attracting those outer electrons, This will tend to make F a little smaller in radius than O.

F and Cl are in the same group, but F is in period 2 and Cl is in period 3. This means that F has 2 shells but Cl has 3 shells and the 3rd shell is further from the nucleus than is the 2nd shell, so Cl will have a larger radius than F.