Question

How would you account for the following:

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

Answer 1

1. The 4d and 5d transition metals have larger atomic sizes and more diffuse d-orbitals compared to 3d metals, allowing better overlap of d-orbitals.
2. This greater overlap facilitates stronger metal-metal covalent bonding in 4d and 5d metals.
3. Also, 4d and 5d metals have higher enthalpies of atomization, indicating stronger interatomic bonding than 3d metals.
4. The stronger interatomic interactions lead to more frequent metal-metal bonding in their compounds.
5. In contrast, 3d metals have more contracted d-orbitals, resulting in weaker orbital overlap and less metal-metal bonding.

Thus, larger, more diffuse orbitals and stronger metallic bonding in 4d and 5d metals cause their compounds to show more metal-metal bonds than 3d metals.