The 4d and 5d series of transition metals have more frequency metal-metal bonding in their compounds than do the 3d metals. Explain.

Explanation

In the same group of d-block elements, the 4d and 5d transition elements have larger size than that of 3d-element. Therefore, their valence electrons are less tightly held and can form metal-metal bond more frequently. This is the reason that melting points and enthalpies of atomisation of elements of 4d and 5d-series are higher than those of 3d series.