Hello

The transition elements are those elements having a partially filled d or f subshell in any common oxidation state. The term transition elements most commonly refers to the d-block transition elements.

In general the electronic configuration of these elements is (n-1)d1-10 ns1-2. The (n-1) stands for the inner d orbitals which may have one to ten electrons and the outermost ns orbital may have one or two electrons.

Chromium is the hardest transition metal

Thankyou