Question

why dont we write valency for D and F block elements​

Answer 1

Answer:

For the d-block and f-block elements, valency is determined not only on the basis of valence electrons but also on d and f orbital electrons. However, the general valencies of these d and f block elements are 2 and 3.

In transition elements the variation in oxidation state is due to involvement of incomplete d-orbitals in addition to electrons of ns orbital. ... Similarly, inner transition elements show variable valency due to incomplete filling of f-orbitals.

Answer 2

For the d-block and f-block elements, valency is determined not only on the basis of valence electrons but also on d and f orbital electrons. However, the general valencies of these d and f block elements are 2 and 3.

In transition elements the variation in oxidation state is due to involvement of incomplete d-orbitals in addition to electrons of ns orbital. ... Similarly, inner transition elements show variable valency due to incomplete filling of f-orbitals.