Problem 1
(a) What is the lanthanoid contraction? (b) Explain how the lanthanoids can be separated from their ores.
Problem 2
Use Hund's rules to derive the ground state of the \(\mathrm{Ce}^{3+}\) ion, and calculate its magnetic moment. (The spin-orbit coupling constant for \(\mathrm{Ce}^{3+}\) is \(1000 \mathrm{cm}^{-1}\) and so the population of states other than the ground state can be neglected at \(298 \mathrm{K} .\) )
Problem 6
Comment on the observations that the electronic spectra of lanthanoid complexes contain many absorptions some of which are weak and sharp and similar to those of the gas-phase metal ions, and some of which are broad and are affected by the ligands present.
Problem 12
Suggest likely products in the following reactions: (a) \(\mathrm{UF}_{4}\) with \(\mathrm{F}_{2}\) at \(570 \mathrm{K} ;\) (b) \(\mathrm{Pa}_{2} \mathrm{O}_{5}\) with \(\mathrm{SOCl}_{2}\) followed by heating with \(\mathrm{H}_{2} ;(\mathrm{c}) \mathrm{UO}_{3}\) with \(\mathrm{H}_{2}\) at \(650 \mathrm{K} ;\) (d) heating \(\mathrm{UCl}_{5}\) (e) \(\mathrm{UCl}_{3}\) with \(\mathrm{NaOC}_{6} \mathrm{H}_{2}-2,4,6-\mathrm{Me}_{3}\).
Problem 16
Discuss the following statements: (a) Thorium forms iodides of formulae \(\mathrm{ThI}_{2}, \mathrm{ThI}_{3}\) and \(\mathrm{ThI}_{4}\). (b) In the solid state, salts of \(\left[\mathrm{UO}_{2}\right]^{2+}\) contain a linear cation. (c) Reactions of \(\mathrm{NaOR}\) with \(\mathrm{UCl}_{4}\) lead to monomeric \(\mathrm{U}(\mathrm{OR})_{4}\) complexes.
Problem 19
Discuss the following: (a) Many actinoid oxides are non-stoichiometric, but few lanthanoid oxides are. (b) The ion \(\left[\mathrm{NpO}_{6}\right]^{5-}\) can be made in aqueous solution only if the solution is strongly alkaline. (c) A solution containing Pu(IV) undergoes negligible disproportionation in the presence of an excess of \(\operatorname{molar} \mathrm{H}_{2} \mathrm{SO}_{4}\).
Problem 20
Give a short account of aspects of the organometallic compounds formed by the lanthanoids and actinoids and highlight major differences between families of organometallic complexes of the \(d\) - and \(f\) -block metals.
