Question

Why transition metals are called transition metals 2?

Answer 1

They are called the "inner transition metals." The transition elements are unique in that they can have an incomplete inner subshell allowing valence electrons in a shell other than the outer shell. Other elements only have valence electrons in their outer shell.

Answer 2

transition metals have an empty or partially vacant d orbital.....so the electrons enter the penultimate shell(n-1) ....also they allow transition between electrons on the d orbital and s orbital...hence are called transition elements