Question

In some of the reactions, thallium resembles aluminum, whereas in other it resembles with group I mentals. Support this statement by giving some evidences.

Answer 1

Aluminium shows a uniform oxidation `+3`. Like aluminium, Tl also shows +3 oxidation state is some of its compounds like `TiCl_(3), Tl_(2)O_(3)` etc. Like `Al, Tl` also forms octahedral complexes : `[AlFe_(6)]^(3-)` and `[TlF_(6)]^(3-)`
Group 1 metals shows an oxidation state of +1. Like group 1 metals. Tl due to inert pair effect also shows +1 oxidation state in some of its compounds such as `Tl_(2)O, TlCl, TlClO_(4)`, etc.
Like group 1 oxides, `Tl_(2)O` is strongly basic.