Question

Are d electrons considered valence electrons?

Answer 1

Generally, no. But the situation gets a bit complex for high values of `n`

Explanation:

`d-`orbitals begin at a principle quantum number of `n=3`, and d electrons are not always valence electrons.

However, at higher values of `n` (such as in the lanthanides/actinides), it is possible for them to become involved in bonding, because the difference in energy between `d-`orbitals and the rest of the nearby orbitals becomes quite small, allowing for easier access to those `d` electrons.