Why it is difficult to interpret the paramagnetic behaviour of actinides?
Answers
Explanation:
Lanthanides and Actinides both show close resemblance because these involve filling of f-subshells. Both have colored ions, low electronegativity, high re-activity and show magnetic properties. However, these also differ from each other as shown in the following explanation.
Lanthanides
Binding energies of 4f electrons are higher.
Maximum oxidation satate exhibited by lanthanides is +4 e.g. Ce4+
4f electrons have greater shielding effect.
Most of their ions are colourless.
They are paramagnetic but magnetic properties can be easily explained.
They do not form complexes easily.
Except promethium, they are non-radioactive.
Their compounds are less basic.
They do not form oxocations.
Actinides
Binding energies of 5f electrons are lower.
Due to lower binding energies they show higher oxidation states such as +4, +5 and +6. Uranium exhibits +6 oxidation state in UF6 and UO2Cl2
5f electrons have poor shielding effect.
Most of their ions are coloured U3+ (red), U4+ (green) and UO22+ (yellow)
They are also paramagnetic but their magnetic properties are very difficult to interpret.
They have much greater tendency to form complexes.
All of them are radioactive.
Their compounds are more basic.
They form oxocations such as UO22+, UO+, NpO2+, PuO2+.