Question

Why are Ni (II) compounds more stable than Pt (II) compounds, but Ni (IV) compounds are less stable than Pt (IV) compounds?

Answer 1

1. Ni (II) compounds are more stable than Pt (II) compounds because Ni requires less energy to lose two electrons; its first two ionization enthalpies are lower than those of Pt.
2. Pt (IV) compounds are more stable than Ni (IV) compounds because the total energy needed to remove four electrons from Pt is less than that for Ni.
3. This difference in stability arises from the ionization enthalpies of Ni and Pt in these oxidation states.

Thus, Ni(II) is more stable; Pt(IV) is more stable due to differences in ionization energies.