Lanthaniden en actiniden

Vakinformatie

Mastervak gedoceerd door Koen Binnemans. Tien punten zijn te verdienen door het schrijven van een grote paper. Het onderwerp hiervan verandert jaarlijks. De andere tien punten staan op het examen waar je nog enkele vragen krijgt over je paper. Niet al te moeilijk voor 6 studiepunten.

Examenvragen

24 januari 2013

1. Discuss the different oxidation states of the actinides and compare with the lanthanides.
2. Discuss the PUREX process
3. A solution of Eu(ClO4)3 in water shows a weak luminescence upon irradiation with light of a wavelength of 393 nm. Upon addition of the sodium salt of pyridine 2,6-dicarboxic acid (dipicalinic acid), a steady increase of the luminescence intensity is observed until the metal to ligand ratio is 1:3. Further addition of the ligand does not appreciably change the luminescence output. However, the luminescence becomes much stronger upon changing the excitation wavelength from 393 to 266 nm.
4. What are MRI contrast agents? What are the requirements for a good MRI contrast agent?
5. Write balanced chemical equations for the following reactions:
   • Reduction of ScF3 by calcium metal
   • reaction between hydrated holmium (III)chloride and thionyl chloride
   • thermal decomposition of (NH4)3NdCl6
   • reaction between Sm metal and 1,2-diiodoethane
6. korte bespreking van het artikel met enkele kleine vraagjes

onbekende datum 2

1. (a) MgCl2 smelt bij 712°C en kookt bij 1712°C; ScCl2 sublimeert bij 800°C; AlCl3 sublimeert bij 178°C. Verklaar deze resultaten aan de hand van het covalent karakter van de binding.(b) ScH2 is een goede geleider. Verklaar.
2. (a) Waarom zijn yttriumverbindingen goede hostmaterialen voor de zwaardere Ln3+-ionen? (b) In welke toepassingen worden deze gedoteerd worden met Eu3+?
3. Bespreek 3 manieren om de lanthaniden te plaatsen in de tabel van Mendeleev.
4. Bespreek 'sensitized luminescence' bij Ln3+-ionen.
5. Welke stoichiometriën vinden we terug bij beta-diketonaatcomplexen. Welke zijn de meest gebruikte?

onbekende datum 3

1. Work out the ground states for Nd3+, Gd3+, Tb3+ and Yb2+.
2. (a) What are MRI contrast agents?(b) What are the requirements for a good MRI contrast agent?
3. (a) Why is the name “rare earths” misleading?(b) What are the rarest elements of the rare earths? (c) What trend can be observed for the abundance of the lanthanide ions over the lanthanide series?
4. (a) Why do La3+, Lu3+ and Gd3+ compounds not show visible luminescence? (b) Explain why f-f transitions in the electronic spectra of lanthanide complexes are weaker than d-d transitions in the corresponding spectra of transition metal complexes.
5. Write the equations for (i) reduction of ScF3 by calcium, (ii) scandium oxide dissolving in potassium hydroxide, (iii) the thermal decomposition of (NH4)3ScCl6. (b) Why is the thermal decomposition of (NH4)3ScCl6 a good way of making pure ScCl3?

onbekende datum 4

1. Work out the ground states for Eu2+, Pm4+, Eu3+, Pr3+ and Er3+.
2. Explain why the electronic spectra of Pr3+ consist of a number of weak, sharp lines, whereas those in the spectrum of V3+ are stronger and broader and less numerous.
3. Ln[N(SiMe3)2]3 are pentane-soluble and sublime in vacuum at 100°C, whereas the much lighter LnCl3 have high melting and boiling points and do not dissolve in organic solvents. Explain why.
4. Something about luminescence and quenching of an Eu3+-complex
5. Write the equations for:
   • reduction of ScF3 by calcium
   • the thermal decomposition of (NH4)3NdCl6
   • the reaction of Sm with 1,2-diiodoethane
   • reaction of hydrated holmiumchloride with thionylchloride</text>