Lecture Notes on d-block and f-block Elements

Introduction to d-block and f-block Elements

• d-block elements: Groups 3-12, d orbitals filled progressively.
• f-block elements: 4f and 5f orbitals filled, located at the bottom of the periodic table.
• Transition metals: d-block, incomplete d subshell in neutral atoms or ions.
• Inner transition metals: f-block, includes lanthanoids (4f) and actinoids (5f).

Characteristics of Transition Elements

• Transition metals have partially filled d orbitals.
• Exhibit multiple oxidation states, form colored compounds, and have magnetic properties.
• High melting and boiling points due to strong metallic bonding.
• Generally hard and dense.

Electronic Configurations

• General configuration for d-block:
  • (n-1)d1–10 ns1–2, exceptions exist due to stability (e.g., Cr 3d5 4s1).
• f-block elements have configurations with variations due to 4f and 5f orbitals.

Position in Periodic Table

• d-block located between s and p blocks.
• f-block placed separately at the bottom.

Oxidation States

• Transition metals display a range of oxidation states.
• Common oxidation states in first row: +2, +3, +4, etc.
• Higher oxidation states possible due to electron sharing.
• Mn shows maximum +7.

Physical Properties

• High tensile strength, ductility, and conductivity.
• Metallic structures, high melting points explained by (n-1)d electron bonding.
• Lattice structures vary: bcc, hcp, ccp.

Trends in Atomic and Ionic Sizes

• Atomic radii decrease across a period due to ineffective shielding of d electrons.
• Lanthanoid contraction: decrease in atomic size across lanthanoids.

Ionisation Enthalpies

• Successive ionisation enthalpies increase gradually.
• Variation in ionisation energy is more regular in transition metals compared to main group elements.

Chemical Reactivity and Electrode Potentials

• Transition metals can form divalent and higher state ions.
• Display catalytic properties due to multiple oxidation states.

Formation of Complexes

• Transition metals form complexes with ligands due to small size and high charge.

Catalytic Properties

• Transition metals and compounds act as catalysts (e.g., V2O5 in Contact Process).

Inner Transition Elements

• Lanthanoids: Similar chemical behavior, single oxidation state (+3).
• Actinoids: Complex chemistry, multiple oxidation states, radioactivity.

Applications

• d-block elements vital in steel production, catalysts, and electronic applications.

Exercises

• Examples and exercises provided to understand electronic configurations, oxidation states, and preparation of compounds like K2Cr2O7 and KMnO4.

Summary

• d-block elements exhibit typical metallic properties; f-block has complex chemistry due to orbital filling.
• Understanding of these elements crucial for various industrial applications.