Chemistry Optional Syllabus

Here is the official UPSC Chemistry Optional syllabus for Paper I and Paper II, arranged paper by paper and unit by unit. Under each unit we give the official text first, then break it into numbered topics, so you can track your preparation and match every previous year question to its topic.

Source. UPSC Civil Services Examination 2026 notification (Examination Notice No. 05/2026-CSE, dated 04.02.2026, pp. 50–53), upsc.gov.in. The Chemistry syllabus has been unchanged in recent years.

Scheme. Two papers of 250 marks each (total 500), 3 hours each. Each paper has two sections (A and B) of four questions each; Questions 1 and 5 are compulsory, and three more are attempted with at least one from each section. The syllabus itself is not divided into sections. Paper I has fifteen numbered units (physical and inorganic chemistry, from Atomic Structure to General Chemistry of ‘f’ Block Elements); Paper II has seven (organic chemistry and spectroscopy, from Delocalised covalent bonding to Spectroscopy), some divided into sub-heads (i), (ii) ….

Syllabus at a glance

Paper	Unit	Topics
Paper I	1. Atomic Structure	2
Paper I	2. Chemical bonding	3
Paper I	3. Solid state	3
Paper I	4. The gaseous state and Transport Phenomenon	2
Paper I	5. Liquid State	1
Paper I	6. Thermodynamics	4
Paper I	7. Phase equilibria and solutions	2
Paper I	8. Electrochemistry	3
Paper I	9. Chemical kinetics	4
Paper I	10. Photochemistry	1
Paper I	11. Surface phenomena and catalysis	2
Paper I	12. Bio-inorganic chemistry	2
Paper I	13. Coordination chemistry	7
Paper I	14. Main Group Chemistry	5
Paper I	15. General Chemistry of ‘f’ Block Element	2
Paper II	1. Delocalised covalent bonding	2
Paper II	2. Reaction mechanisms	8
Paper II	3. Pericyclic reactions	3
Paper II	4. Polymers	2
Paper II	5. Synthetic Uses of Reagents	3
Paper II	6. Photochemistry	1
Paper II	7. Spectroscopy	5

Paper I

1. Atomic Structure

1.1 Uncertainty principle and Schrödinger equation

• Heisenberg’s uncertainty principle
• Schrödinger wave equation (time independent)
• Interpretation of wave function

1.2 Particle in a box and hydrogen atom

• Particle in one-dimensional box
• Quantum numbers
• Hydrogen atom wave functions
• Shapes of s, p and d orbitals

2. Chemical bonding

2.1 Ionic bonding

• Characteristics of ionic compounds
• Lattice energy
• Born-Haber cycle

2.2 Covalent bond and valence bond theory

• General characteristics of covalent bond
• Polarities of bonds and dipole moments
• Valence bond theory
• Resonance and resonance energy

2.3 Molecular orbital theory

• LCAO method
• Bonding in H2+, H2, He2+ to Ne2, NO, CO, HF, CN–
• Comparison of VB and MO theories
• Bond order, bond strength and bond length

3. Solid state

3.1 Crystal systems and X-ray diffraction

• Crystal systems
• Designation of crystal faces, lattice structures and unit cell
• Bragg’s law
• X-ray diffraction by crystals

3.2 Close packing and ionic structures

• Close packing
• Radius ratio rules and limiting radius ratios
• Structures of NaCl, ZnS, CsCl, CaF2

3.3 Defects and semiconductors

• Stoichiometric and nonstoichiometric defects
• Impurity defects
• Semi-conductors

4. The gaseous state and Transport Phenomenon

4.1 Real gases and critical phenomena

• Equation of state for real gases
• Intermolecular interactions
• Critical phenomena and liquefaction of gases

4.2 Kinetic theory and transport

• Maxwell’s distribution of speeds
• Intermolecular collisions, collisions on the wall and effusion
• Thermal conductivity and viscosity of ideal gases

5. Liquid State

5.1 Surface tension and capillarity

• Kelvin equation
• Surface tension and surface energy
• Wetting and contact angle
• Interfacial tension and capillary action

6. Thermodynamics

6.1 First law of thermodynamics

• Work, heat and internal energy
• First law

6.2 Second law and entropy

• Second law
• Entropy as a state function
• Entropy changes in various processes
• Reversibility and irreversibility

6.3 Free energy and Maxwell relations

• Free energy functions
• Thermodynamic equation of state
• Maxwell relations
• Dependence of U, H, A, G, Cp, Cv, α and β on T, V and P
• J-T effect and inversion temperature

6.4 Equilibrium and third law

• Criteria for equilibrium
• Equilibrium constant and thermodynamic quantities
• Nernst heat theorem
• Third law of thermodynamics

7. Phase equilibria and solutions

7.1 Phase equilibria

• Clausius-Clapeyron equation
• Phase diagram for a pure substance
• Phase equilibria in binary systems
• Partially miscible liquids and critical solution temperatures

7.2 Partial molar and excess quantities

• Partial molar quantities, significance and determination
• Excess thermodynamic functions and their determination

8. Electrochemistry

8.1 Debye-Hückel theory

• Strong electrolytes
• Debye-Hückel limiting law
• Equilibrium and transport properties

8.2 Galvanic cells and e.m.f.

• Galvanic and concentration cells
• Electrochemical series
• Measurement of e.m.f. and applications
• Fuel cells and batteries

8.3 Electrode processes and electroanalytical techniques

• Double layer
• Rate of charge transfer, current density
• Overpotential
• Amperometry
• Ion selective electrodes

9. Chemical kinetics

9.1 Rate equations and order of reaction

• Differential and integral rate equations
• Zeroth, first, second and fractional order reactions

9.2 Complex reactions

• Reverse, parallel, consecutive and chain reactions
• Branching chain and explosions

9.3 Temperature and pressure effects; theories of reaction rates

• Effect of temperature and pressure on rate constant
• Collision theory
• Transition state theory

9.4 Fast reactions

• Stop-flow method
• Relaxation methods

10. Photochemistry

10.1 Photochemistry

• Absorption of light
• Decay of excited state by different routes
• Hydrogen–halogen photochemical reactions
• Quantum yields

11. Surface phenomena and catalysis

11.1 Adsorption and surface area

• Adsorption from gases and solutions on solids
• Langmuir and B.E.T. isotherms
• Determination of surface area

11.2 Heterogeneous catalysis

• Characteristics and mechanism of reaction on heterogeneous catalysts

12. Bio-inorganic chemistry

12.1 Metal ions in biological systems

• Role in ion-transport across membranes (molecular mechanism)

12.2 Oxygen-uptake proteins, cytochromes and ferredoxins

13. Coordination chemistry

13.1 Bonding, magnetism and spectra of complexes

• Valence bond theory
• Crystal field theory and its modifications
• Magnetism
• Electronic spectra of metal complexes

13.2 Isomerism, nomenclature and stereochemistry

• Isomerism in coordination compounds
• IUPAC nomenclature
• Stereochemistry of 4- and 6-coordinate complexes

13.3 Stability and reaction mechanisms of complexes

• Chelate effect and polynuclear complexes
• Trans effect and its theories
• Substitution in square-planar complexes
• Thermodynamic and kinetic stability

13.4 Metal carbonyls and nitrosyls

• EAN rule
• Synthesis, structure and reactivity of metal carbonyls
• Carboxylate anions and carbonyl hydrides
• Metal nitrosyl compounds

13.5 Organometallic complexes

• Complexes with aromatic systems
• Metal olefin and alkyne complexes
• Cyclopentadienyl complexes

13.6 Organometallic reactions and fluxional molecules

• Coordinative unsaturation
• Oxidative addition reactions
• Insertion reactions
• Fluxional molecules and their characterization

13.7 Metal–metal bonds and clusters

• Compounds with metal–metal bonds
• Metal atom clusters

14. Main Group Chemistry

14.1 Boranes and borazines

14.2 Phosphazenes

• Phosphazenes and cyclic phosphazene

14.3 Silicates and silicones

14.4 Interhalogen and noble gas compounds

• Interhalogen compounds
• Noble gas compounds

14.5 Sulphur–nitrogen compounds

15. General Chemistry of ‘f’ Block Element

15.1 Lanthanides and actinides

• Separation
• Oxidation states
• Magnetic and spectral properties

15.2 Lanthanide contraction

Paper II

1. Delocalised covalent bonding

1.1 Aromaticity, anti-aromaticity and annulenes

• Aromaticity
• Anti-aromaticity
• Annulenes

1.2 Non-benzenoid aromatic systems

• Azulenes
• Tropolones
• Fulvenes
• Sydnones

2. Reaction mechanisms

2.1 Methods of study of mechanisms

• Kinetic and non-kinetic methods
• Isotopic method, cross-over experiment, intermediate trapping, stereochemistry
• Energy of activation
• Thermodynamic and kinetic control

2.2 Reactive intermediates

• Carbonium ions and carbanions
• Free radicals
• Carbenes
• Benzynes and nitrenes

2.3 Aliphatic nucleophilic substitution

• SN1, SN2 and SNi mechanisms
• Neighbouring group participation

2.4 Aromatic substitution and heterocycles

• Electrophilic and nucleophilic aromatic substitution
• Pyrrole, furan, thiophene and indole

2.5 Elimination reactions

• E1, E2 and E1cb mechanisms
• Saytzeff and Hoffmann orientation
• Pyrolytic syn elimination: acetate pyrolysis, Chugaev and Cope eliminations

2.6 Addition reactions

• Electrophilic addition to C=C and C≡C
• Nucleophilic addition to C=O, C≡N, conjugated olefins and carbonyls

2.7 Rearrangements

• Pinacol-pinacolone, Hoffmann, Beckmann, Baeyer-Villiger, Favorskii, Fries, Claisen, Cope, Stevens and Wagner-Meerwein rearrangements

2.8 Named reactions and condensations

• Aldol, Claisen, Dieckmann, Perkin, Knoevenagel, Stobbe, benzoin and acyloin condensations
• Wittig, Clemmensen, Wolff-Kishner, Cannizzaro and von Richter reactions
• Fischer indole, Skraup and Bischler-Napieralski syntheses
• Sandmeyer, Reimer-Tiemann and Reformatsky reactions

3. Pericyclic reactions

3.1 Electrocyclic reactions

• Classification and examples
• Woodward-Hoffmann rules
• FMO approach

3.2 Cycloaddition reactions

• [2+2] and [4+2] cycloadditions

3.3 Sigmatropic shifts

• [1,3], [3,3] and [1,5] shifts

4. Polymers

4.1 Synthetic polymers

• Preparation and properties
• Polyethylene, polystyrene, polyvinyl chloride, teflon
• Nylon, terylene
• Synthetic and natural rubber

4.2 Biopolymers

• Structure of proteins
• DNA and RNA

5. Synthetic Uses of Reagents

5.1 Oxidising reagents

• OsO4, HIO4, CrO3, Pb(OAc)4, SeO2, MCPBA

5.2 Hydride, borane and dissolving-metal reagents

• B2H6
• LiAlH4
• NaBH4
• Na-liquid NH3

5.3 NBS and n-BuLi

6. Photochemistry

6.1 Organic photochemistry

• Photochemical reactions of simple organic compounds
• Excited and ground states, singlet and triplet states
• Norrish Type I and Type II reactions

7. Spectroscopy

7.1 Rotational spectroscopy

• Diatomic molecules
• Isotopic substitution and rotational constants

7.2 Vibrational (IR) spectroscopy

• Diatomic and linear triatomic molecules
• Functional group frequencies

7.3 Electronic (UV-visible) spectroscopy

• Singlet and triplet states
• n→π* and π→π* transitions
• Woodward-Fieser rules
• Charge transfer spectra

7.4 NMR spectroscopy

• ¹H NMR basic principle
• Chemical shift
• Spin-spin coupling and coupling constants

7.5 Mass spectrometry

• Parent, base and metastable peaks
• McLafferty rearrangement

Total: 67 numbered topics across 22 units.

Last updated: 30 October 2026