Yea, I meant group III. According to my professor, the electron added from Group II to Group III in the p orbital actually has a lower force of attraction to the nucleus because the previous s orbital electrons (which have higher penetration based on radial probability graphs) shield that electron in the p orbital. I just thought since that one electron in the p orbital is not as attracted to the nucleus than the electrons in the s orbitals in the previous element in Group II, it would move away from the nucleus and increase the atomic radius.