Briefly explain why the Zinc and scandium are not classified among the transition elements.

✓ Both have no ion that has a partially filled d-orbital .

Zinc

• Forms only one ion ( other transition elements forms two or more )
• Zn²+ has a completely full 3d sub-shell .
• Zn²+ has the following electronic configuration 1s²2s²3s²3p⁶3d¹⁰ or [Ar] 3d¹⁰ .

Scandium

• Forms only one ion .
• Sc³+ has no 3d or 4s electrons.
• Sc³+ has electronic configuration 1s²2s²3s²3p⁶

In making ions of transition elements, the ns electrons are removed first.