increases and electron electron repulsions repulsion increases .
c . Lanthanoid Contraction : The steady decrease in the atomic and ionic radii of the transition metals as the atomic number increases . This is because of filling of 4f orbitals before the 5d orbitals . This contraction is size is quite regular . This is called lanthanoid contraction . It is because of lanthanoid contraction that the atomic radii of the second row of transition elements are almost similar to those of the third row of transition elements .
d . Ionisation enthalpy : There is slight and irregular variation in ionization energies of transition metals due to irregular variation of atomic size . The I . E . of 5d transition series is higher than 3d and 4d transition series because of Lanthanoid Contraction .
e . Oxidation state : Transition metals show variable oxidation states due to tendency of ( n-1 ) d as well as ns electrons to take part in bond formation .
f . Magnetic properties : Most of transition metals are paramagnetic in nature due to presence of unpaired electrons . It increase s from Sc to Cr and then decreases because number of unpaired and then decrease because