Assign reasons for the following:
i) Copper(+1) ion is not known in aqueous solution.
ii) Actinoids exhibit a greater range of oxidation states than lanthanoids.
i) Copper(+1) ion is not known in aqueous solution.
ii) Actinoids exhibit a greater range of oxidation states than lanthanoids.
Solution
(i) Aqueous Cu immediately disproportionates:
because the high hydration enthalpy of Cu more than offsets copper's second ionisation enthalpy — so Cu(+1) is not found in water.
(ii) In the actinoids the 5f, 6d and 7s orbitals are very close in energy; electrons from all of them can be used in bonding, giving states from +3 up to +7. Lanthanoid 4f electrons are deeply buried, confining them essentially to +3.
because the high hydration enthalpy of Cu more than offsets copper's second ionisation enthalpy — so Cu(+1) is not found in water.
(ii) In the actinoids the 5f, 6d and 7s orbitals are very close in energy; electrons from all of them can be used in bonding, giving states from +3 up to +7. Lanthanoid 4f electrons are deeply buried, confining them essentially to +3.
CBSE Class 12 Board · 2011 · Delhi · Subjective