Question

Why do the d-block elements exhibit a larger number of oxidation states than the f-block elements?

Explain the following:

d-block elements exhibit more oxidation states than f-block elements.

Answer 1

1. d-block elements have (n − 1)d and ns orbitals close in energy, allowing variable involvement of these electrons in bonding.
2. They can lose different numbers of (n − 1)d and ns electrons, leading to multiple oxidation states.
3. In contrast, f-block elements have electrons in the more inner 4f or 5f orbitals, which are more deeply buried and less available for bonding.
4. f-electrons are well shielded and have similar energy, limiting the range of stable oxidation states.
5. Actinoids (f-block) show more oxidation states than lanthanoids due to involvement of 5f and 6d orbitals, but still fewer than d-block.

Hence, the accessibility and energy proximity of d and s electrons in d-block elements result in a larger variety of oxidation states compared to f-block elements.