How would you account for the following :
Among lanthanoids, Ln (III) compounds are predominant. However occasionally in solutions or in solid compounds +2 and +4 ions are also obtained.
Lanthanoids exhibit occasionally +2, +4 ions because of extra stability of empty, half-filled and completely filled 4f- subshell respectively i e, 4f0,4f7 , 4f14 configuration.
