Question

Sc(Z = 21) is a transition element but Zn (Z = 30) is not because :

• A. Both $Sc^{3+}$ and $Zn^{2+}$ ions are colourless and form white compounds
• B. In case of $Sc, 3d$ orbitals are partially filled but in $Zn$ these are filled
• C. Last electron is assumed to be added to 4s level in case of Zn
• D. Both Sc and Zn do not exhibit variable oxidation states

Answer 1

The Correct Option is B

The question asks why Scandium (Sc) is considered a transition element whereas Zinc (Zn) is not, and provides options related to their electronic configurations and properties.

To determine why Scandium is a transition element and Zinc is not, we should examine their electronic configurations:

• Scandium (Sc): Atomic number \(Z = 21\). The electronic configuration is \( \text{[Ar]} \, 3d^1 \, 4s^2\).
• Zinc (Zn): Atomic number \(Z = 30\). The electronic configuration is \( \text{[Ar]} \, 3d^{10} \, 4s^2\).

From these configurations, we can see:

• Scandium has a partially filled 3d orbital (\(3d^1\)), which is a characteristic of transition elements. Transition elements typically have partially filled d orbitals that allow them to form various oxidation states and often form colored compounds.
• Zinc has a completely filled 3d orbital (\(3d^{10}\)), meaning it does not typically exhibit the characteristic properties of transition metals such as multiple oxidation states (Zn mostly exhibits +2) or the formation of colored compounds.

Hence, the correct reason why Scandium is a transition metal while Zinc is not is: In case of $Sc, 3d$ orbitals are partially filled but in $Zn$ these are filled.