Both the
dichromate and the permanganate ions are strong oxidising agents The two series of inner transition elements, lanthanoids and actinoids constitute
the f-block of the periodic table With the successive filling of the inner orbitals, 4f, there
is a gradual decrease in the atomic and ionic sizes of these metals along the series
(lanthanoid contraction) This has far reaching consequences in the chemistry of the
elements succeeding them