Using the data reported in the figure below, explain:

a$)$ how ionic radii change with atomic number for s and p$-$block elements;

b$)$ how radii change for an isoelectronic cation series $($select one series at your will$)$;

c$)$ for any element with more than one oxidation state, describe how cation radius

changes with increasing oxidation number;

d$)$ how the cation radius changes with coordination number.

Consider the Shannon$-$Prewitt model and explain which contribution it provides to rationalize the

trends reported above.

$($Values of radii on the ordinate are expressed in angstrom, $1=10-10$ m$)$