Scandium (z = 21) is a transition element but zinc (z = 30) is not. Explain.

Explanation

`Sc (Z=21)` has electronic configuration : `[Ar] 3d^1 4s^2`
`Zn (Z = 30)` has electronic configuration : `[Ar] 3d^10 4s^2`

As Sc has incompletely filled 3d-orbitals in its ground state, it is regarded as a transition elements On the other hand Zn atom has completely filled, d-orbitals `(3d^10)` in its ground state as well as in its oxidised state (`Zn^(2+)` with `3d^(10)` configuration) hence it is not regarded as a transition element.