Which atoms increase in size when they become ions? Explain you answer. Cs, I, Zn, O, Sr, Al

Hello,

Atoms increase in size when they become negative ions. The negative indicates than the electrons repel each other to a greater extent and overpower the positive pull of the nucleus, spreading out farther.

The ones that become negative ions are I and O. They become I- and O2-, and increase in size. <<

The list of above elements can be divided into two groups:
metals - Cs, Zn, Sr, Al
and
nonmetals - I, O
Metals are atoms that tend to lose their valence electrons. When they do, they lose their entire valence shells. Consequently, their (positive) ions are smaller than their (neutral) atoms because their ions have one less shell than their atoms.
Nonmetals are atoms that tend to gain electrons to complete their valence shells). When that happens, their valence shells are fuller, and the added repulsion between negatively charged electrons makes their valence shells swell up. Consequently, their (negative) ions are larger than their (neutral) atoms.

I won't answer which ones because you won't learn, but I will say this: atoms that become ions by GAINING an electron always become bigger because the electrons have to compensate for increased repulsive force, so the electron shells become bigger.