Chapter 23: Transition Metals and Coordination Chemistry

Students explore the d-block elements across periods four, five, and six, learning how electron configuration in d orbitals relates to chemical behavior, magnetic properties, and catalytic activity. The chapter introduces coordination chemistry concepts, including ligand types, coordination numbers, and the geometry of coordination complexes such as tetrahedral, square planar, and octahedral arrangements. Crystal field theory provides the theoretical framework for understanding how ligand fields split d-orbital energies, explaining color, magnetism, and stability of complexes. The formation and equilibrium of coordination complexes are examined through stability constants and complex ion formation reactions. Applications of transition metals span industrial catalysis, where metals like iron, nickel, and platinum drive essential chemical transformations, to biological systems where iron-containing hemoglobin and cobalt-based cobalamins perform critical functions. The chapter addresses coordination nomenclature, isomerism in complexes including geometric and optical isomerism, and the role of chelating agents in medical treatments and environmental remediation. Students also encounter practical industrial applications such as metal refining, production of dyes and pigments through coordination chemistry, and the use of transition metal catalysts in petroleum processing and organic synthesis. By integrating structure, bonding theory, and real-world applications, this chapter demonstrates how transition metals and their coordination compounds are central to modern chemistry, medicine, and materials science.