- Chemical periodicity and s- and p-block elements
- d- and f-block elements: Transition metals and Lanthanides and Actinides
- Coordination chemistry: Introduction, Werner's theory, IUPAC nomenclature, bonding and stereochemistry, and electronic spectra of coordination compounds
- Organometallic compounds: Structure, bonding, and reaction mechanisms
- Bioinorganic chemistry: Metal ions in biological systems, oxygen transport, electron transfer, and nitrogen fixation


- Thermodynamics: Laws, state and path functions, work and heat, reversible and irreversible processes, entropy, free energy, and spontaneity
- Chemical equilibrium: Equilibrium constants, Le Chatelier's principle, acids and bases, pH and buffer solutions, solubility product, and common ion effect
- Electrochemistry: Electrochemical cells, Nernst equation, conductance, and conductometric titrations
- Quantum chemistry: Principles of quantum mechanics, wave-particle duality, Schrödinger equation, atomic and molecular orbitals, and electronic spectroscopy
- Spectroscopy: Rotational, vibrational, electronic, and magnetic resonance spectroscopy


- Basic concepts: Structure, properties, and classification of organic compounds
- Stereochemistry: Optical isomerism, conformational analysis, and stereoselective reactions
- Reaction mechanisms: Substitution, addition, elimination, and rearrangement reactions
- Reactive intermediates: Carbocations, carbanions, free radicals, and carbenes
- Organic synthesis: Retrosynthetic analysis, functional group transformations, and protecting groups


- Principles of qualitative and quantitative analysis
- Gravimetric and volumetric analysis
- Electroanalytical methods: Potentiometry, conductometry, and polarography
- Spectroscopic methods: UV-Vis, IR, NMR, and Mass spectrometry
- Chromatographic methods: TLC, HPLC, GC, and Ion-exchange chromatography


- Environmental pollution: Sources, effects, and control measures
- Water and soil pollution: Analysis and treatment methods
- Atmospheric pollution: Acid rain, ozone depletion, and global warming
- Green chemistry: Sustainable practices and applications

It is important to note that the above list is not exhaustive, and the UPSC Chemistry Optional subject may cover additional topics or subtopics. It is advisable to refer to the official UPSC syllabus and previous years' question papers for a comprehensive understanding of the subject.