Question

Why do the negative ions have larger radii than the positive ions?

Answer 1

since negative ions(anions) are formed due to gain of electrons......but there is no change in effective nuclear charge...since protons no. are same...hence nucleus has less tendency to pull the outermost recently added electrons.....and radii is larger then before..

while in case of positive ions(cations) it is formed by loosing an electron....but effective nuclear charge is not change....as electron are less now as compare to earlier one the force exerted by nucleus is now more on outermost electron to pull it towards itself...hence the radii becomes less then earlier one....