why do transition metals have variable oxidation states?
they form ions by losing electrons from 4s and 3d orbitals which are at similar energy levels so require a similar amount of energy to remove electrons
there's also a small increase in successive ionisation energies so multiple electrons can be removed from orbitals to form stable ions
why s-block metals don't have variable oxidation states
there's a large jump in ionisation energies after s electrons have been removed
maximum oxidation states
number of 4s electrons + number of unpaired 3d electrons
effect of nuclear charge
increases from Fe across s don't lose electrons as readily due to greater ionisation energy so have fewer and lower oxidation states
showing variable oxidation states
shake solution of ammonium vanadate (v) in dilutesulfuric acid and zinc
different colours produced depending on oxidation number~
