Question

On what grounds can you say that scandium $(\text{Z}=21)$ is a transition element but zinc $(\text{Z}=30)$ is not one?

• A. Incompletely filled 3d orbitals in Sc
• B. Coloured compounds
• C. Variable oxidation state
• D. None of the above

Answer 1

Answer: (A)

Scandium is one of the two elements in the first transition metal period which has only one oxidation state (zinc is the other, with an oxidation state of +2).

On the basis of incompletely filled 3d orbitals, scandium $\left(3d^1\right)$ has incompletely filled d-orbitals $(3{\left(\text{d}\right)}^1)$ in its ground state, so it is regarded as a transition element.

On the other hand, zinc $(\text{Z}=30)$ has completely filled d-orbitals $\left(3{\mathrm{d}}^{10}\right)$ in its ground state.