Why does hg2+ have a negative standard entropy
(-32.2j. k-1mol-1) and hg
22+have a positive standard entropy
(84.5j. k-1mol-1)?

Hg∧2+ has a negative standard entropy because the ions are highly solvated in aqueous phase; smaller the ionic size, the more highly it is surrounded by solvated ions. Therefore it will be in highly ordered state hence the entropy decreases.

Hg2 ^2+ has a positive standard entropy because the ionic size of Hg^2+ is smaller than Hg2 ^2+, so therefore the Hg^2+ is highly solvated and that means that it is in highly ordered state.  Hg2 ^2+  is not highly solvated so it will have a positive entropy

Explanation:

The values of standard entropy of aqueous ions has a negative standard entropy because the ions are highly solvated in aqueous phase; smaller the ionic size, the more highly it is surrounded by solvated ions. Therefore it will be in highly ordered state hence the entropy decreases.

Hg2 ^2+ has a positive standard entropy because the ionic size of Hg^2+ is smaller than Hg2 ^2+, so therefore the Hg^2+ is highly solvated and that means that it is in highly ordered state.  Hg2 ^2+  is not highly solvated so it will have a positive entropy

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."