@YouKnowMe D

All four ions are going to the same noble gas configuration

more will be the negative charge on the ion, the bigger it will become, as the effective nuclear charge on the valence electrons will go down

more is the positive charge on an ion, effective nuclear charge on valence shell increase and hence size decreases

@YusufHasan More negative charge means that the atom has accepted Electrons?

So there would more attraction between nucleus and electrons which would result in smaller ironic radius.

But more Electrons would also result in shielding effect.

I don't know how to know which factor is greater.

@YusufHasan I do understand the answer. Thanks :-)

But I think my concept is not clear.

More negative charge means that you have stuffed more electrons into the atom than the number of protons. The shielding stays the same, because shielding is done by inner electrons on the outer electrons, so if electrons are being filled in the outermost shell itself (known commonly as valence shell) then obviously shielding stays the same, right?

The thing which changes is this: more electrons in the outer shell means that electrons now outnumber protons, so the attractive effect of the nucleus will be severely hampered, as there are simply not enough protons to setup equivalent coumlombic interactions with the newly added electrons

@YusufHasan Book says B

@YusufHasan Right

On top of that, the newly added electrons bring a nuisance with them- more electron-electron repulsion, as more electrons have been stuffed in the same volume. This repulsion will ultimately motivate the electrons to move away from each other, and essentially, spread out over a larger volume. And an increased volume directly relates to an increased radius

@YouKnowMe The book is wrong, the answer is D

So in totality, more electron electron repulsions, and a reduced attractive hold of the nucleus over the newly added electrons in the valence shell will lead to a net increase in ionic radius

Okay till here?

Wait

@YusufHasan So shielding effect is larger than nuclear attraction.

@YouKnowMe There is no idea of "larger" or "smaller" here...The shielding effect doesn't change in going from a neutral atom to an anion, as shielding is done by inner electrons, and so any variation in shielding will only occur if you somehow were disturbing the inner electrons(those jusr behind the valence shell). But electrons are being added to the valence shell, that is, the outermost shell...So the shielding received by them is more or less similar as before

it may have become a bit worse, but certainly not become more prominent. More important is looking at the nuclear charge, that is, how much can it attract the valence shell

Since their is an imbalance in the number of attracting particles

so, overall, the repulsive interactions b/w electrons dominate

and lead to an overall increase in anionic size

it's all a game of numbers here

Does it make sense?

@YusufHasan Hmmm

or are you still not convinced?

@YusufHasan I am convinced 95%.

what's the 5%?

I have to practice more questions like this.

Yeah okay,....and in a similar manner, the cation's size decreases, because now, protons outnumber electrons, and so number of proton electron attractive interactions become more than electron electron repulsion

@YusufHasan Thanks a Lot.