Transition Metals and Their Properties - SS3 Chemistry Lesson Note

Transition metals are a group of elements found in the d-block of the periodic table. They are called "transition" metals because they form a transition between the highly reactive alkali metals and alkaline earth metals (found in Groups 1 and 2) and the less reactive metals found in the p-block of the periodic table. Transition metals have unique properties and play essential roles in various chemical and industrial processes. Let's explore the properties and characteristics of transition metals in detail:

Electron Configuration: Transition metals have partially filled d-orbitals, which contribute to their characteristic properties. Their general electron configuration is (n-1)d^(1-10) ns^(1-2), where n represents the principal quantum number of the outermost electron shell.

Variable Valency: Transition metals often exhibit variable valency, meaning they can form ions with different charges by losing different numbers of electrons from their d-orbitals. This property makes them versatile in forming various complex compounds and coordination complexes.

Formation of Complexes: Transition metals have a strong tendency to form coordination complexes with ligands. These complexes are characterised by the coordination of ligands (such as water, ammonia, or chloride ions) to the central metal ion. The formation of complexes imparts distinct colours to transition metal compounds, making them often brightly coloured.

High Melting and Boiling Points: Transition metals generally have high melting and boiling points compared to the s-block and p-block elements. This is due to the presence of strong metallic bonds resulting from the delocalization of electrons in the d-orbitals.

High Density: Transition metals tend to have high densities, which is a consequence of their relatively large atomic masses and closely packed crystal structures.

Malleability and Ductility: Like other metals, transition metals are malleable (can be hammered into thin sheets) and ductile (can be drawn into thin wires) due to their metallic bonding.

Catalytic Activity: Many transition metals, especially in their ionic forms, exhibit excellent catalytic activity. They participate in catalysis by providing active sites for chemical reactions to occur.

Magnetic Properties: Several transition metals and their compounds display magnetic properties due to the presence of unpaired electrons in their d-orbitals. Some transition metals are ferromagnetic (e.g., iron), while others are paramagnetic or antiferromagnetic.

Alloy Formation: Transition metals are widely used in alloy formation, where they are combined with other elements to enhance specific properties, such as strength, hardness, and corrosion resistance.

Use in Industrial Processes: Transition metals are vital in various industrial processes, including the production of steel (iron and chromium), catalytic converters (platinum and palladium), and electrical wiring (copper).

Biological Roles: Several transition metals are essential micronutrients in biological systems, playing crucial roles as cofactors in enzymes and electron transport processes.

Overall, transition metals exhibit a rich variety of properties that make them indispensable in numerous applications, ranging from metallurgy and electronics to catalysis and medicine. Their ability to form complex compounds and participate in redox reactions gives them a unique place in the world of chemistry and materials science.