Chemical periodicity of other elements

Need to know

What you need to know

• Based on this definition, Scandium (Sc) and Zinc (Zn) are d-block elements but are not considered true transition elements.
• Scandium's only stable ion is $Sc^{3+}$, which has the configuration $[Ar] 3d^0$ (an empty d sub-shell).
• Zinc's only stable ion is $Zn^{2+}$, which has the configuration $[Ar] 3d^{10}$ (a full d sub-shell).
• Elements like Copper ($Cu \rightarrow Cu^{2+} [Ar] 3d^9$) and Iron ($Fe \rightarrow Fe^{2+} [Ar] 3d^6$) are classic examples of transition elements.

Explanation

The Periodic Table's Specialists

1. Transition metals are d-block elements with a partially filled d subshell in at least one stable ion. This structure leads to variable oxidation states and the formation of coloured compounds.
2. Their ability to switch between oxidation states allows them to act as catalysts, providing an alternative reaction pathway with lower activation energy. Key examples are Iron in the Haber process and Vanadium(V) oxide in the Contact process.
3. Unlike the predictable trends in Groups 1, 2, and 17 (e.g., reactivity increasing down Group 1), transition metals show more subtle variations. Their properties contrast sharply with the highly reactive alkali metals and halogens.
4. Across the first d-block row (Sc to Zn), atomic radii remain relatively constant due to the poor shielding of 3d electrons. Their general electronic configuration is [Ar] 3dⁿ 4s², but elements like Zinc, with a full d-subshell, don't behave as typical transition metals.