Actinides exhibit more number of oxidation states than lanthanides because of lesser energy difference between the 5f and 6d orbitals than that between the 4f and 5d orbitals. Related Theory Actinides have a very small energy gap between 5f and 6d orbitals, so they can easily form a variety of configurations and hence they are found to be stable in various oxidation states. Lanthanides are comparatively less electropositive than actinides and due to that reason, they are less reactive than actinides.