VKC Mains Notes for UPSC Chemistry
One set of notes per topic, written once for Civil Services, IFoS and Geo-Scientist Mains. Each note tags every past-year question of all three exams, with diagrams you can draw in the hall and a one- or two-page short-notes version for revision.
Preparing for Geo-Scientist Prelims? Read the Prelims notes, unit by unit.
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Topics
All 73 syllabus topics, grouped by area. Search a word or pick your exam; every topic has full notes and a short-notes version. Updates are announced on Telegram.
Physical chemistry 23 topics
- 1.1Postulates of quantum mechanics: operators, eigenfunctions, Hermitian operators and acceptable wave functionsQuantum chemistry · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 11 PYQ parts, 78 marks (2021–2025)CSEIFoSGeo Mains
- 1.2Uncertainty principle, de Broglie relation and wave–particle dualityQuantum chemistry · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 7 PYQ parts linked (2021–2025)CSEIFoSGeo Mains
- 1.3Particle in a one-dimensional boxAtomic structure · Civil Services Paper I (also IFoS Paper I, Geo-Scientist Paper II) · 6 PYQ parts, 75 marksCSEIFoSGeo Mains
- 1.4Hydrogen atom: Schrödinger equation, quantum numbers, radial distribution, nodes and orbital shapesQuantum chemistry · Civil Services Paper I, IFoS Paper I · 8 PYQ parts, 68 marks (2021–2025)CSEIFoS
- 3.1Crystal systems, Miller indices, Bragg's law and radius ratioSolid state · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 34 PYQ parts, 296 marks (2021–2025)CSEIFoSGeo Mains
- 3.2Defects in solids, non-stoichiometry and semiconductorsSolid state · Civil Services Paper I, IFoS Paper I, Geo-Scientist Papers I and II · 24 PYQ parts, 177 marks (2021–2025)CSEIFoSGeo Mains
- 4.1Real gases: van der Waals equation, critical constants, Boyle temperatureGaseous state · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 28 PYQ parts, 215 marks (2021–2025) + 5 Geo Prelims questionsCSEIFoSGeo PrelimsGeo Mains
- 4.2Kinetic theory of gases: Maxwell distribution, collisions, mean free path, effusion and transportGaseous state · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 12 PYQ parts, 95 marks (2021–2025)CSEIFoSGeo Mains
- 4.3Liquid state: surface tension, Kelvin equation, capillary action, viscosity and liquid crystalsLiquid state · Civil Services Paper I, IFoS Paper I · 9 PYQ parts, 75 marks (2021–2025) + 1 Geo Prelims questionCSEIFoSGeo Prelims
- 5.1First law of thermodynamics: work, heat, enthalpy, adiabatic changes, Joule–Thomson effect, thermochemistryThermodynamics · Civil Services Paper I, IFoS Paper I, Geo-Scientist Prelims · 9 PYQ parts, 73 marks (2021–2025) + 35 Geo Prelims questionsCSEIFoSGeo PrelimsGeo Mains
- 6.1Second and third laws: entropy, Gibbs and Helmholtz energies, Maxwell relationsThermodynamics · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 15 PYQ parts, 139 marks (2021–2025) + 30 Geo Prelims questionsCSEIFoSGeo PrelimsGeo Mains
- 6.2Chemical potential, partial molar quantities, Gibbs–Duhem equation, fugacity and activityThermodynamics · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 14 PYQ parts, 115 marks (2021–2025)CSEIFoSGeo Mains
- 6.3Chemical equilibrium: ΔG° and K, Kp, Kc and Kx, van ’t Hoff isochore and isobarThermodynamics · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 12 PYQ parts, 98 marks (2021–2025) + 2 Geo Prelims questionsCSEIFoSGeo PrelimsGeo Mains
- 6.4Statistical thermodynamics: Boltzmann distribution, partition functions, Sackur–Tetrode equationStatistical thermodynamics · IFoS Paper I · 5 PYQ parts, 55 marks (2021–2025)IFoS
- 7.1Phase rule, phase diagrams, Clausius–Clapeyron equation, eutectics and partially miscible liquidsPhase equilibria · Civil Services Paper I, IFoS Paper I · 15 PYQ parts, 176 marks (2021–2025) + 1 Geo Prelims questionCSEIFoSGeo Prelims
- 7.2Solutions: Raoult’s and Henry’s laws, colligative properties, van ’t Hoff factor and activityPhase equilibria and solutions · Geo-Scientist Prelims, Civil Services Paper I, IFoS Paper I · 42 Geo Prelims questions (2021–2026) + 1 IFoS Mains partCSEIFoSGeo PrelimsGeo Mains
- 8.2Electrochemical cells: Nernst equation, emf and electrodesElectrochemistry · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 39 PYQ parts, 326 marks (2021–2025)CSEIFoSGeo PrelimsGeo Mains
- 8.3Electrolytes: conductance, Kohlrausch, Debye–Hückel and transport numbersElectrochemistry · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II and Prelims · 14 Mains parts (124 marks) and 44 Prelims questionsCSEIFoSGeo PrelimsGeo Mains
- 8.4Electrode kinetics: double layer, overpotential, Butler–Volmer and Tafel equations, polarography and voltammetryElectrochemistry · Civil Services Paper I, IFoS Paper I · 6 PYQ parts, 53 marks (2021–2025)CSEIFoS
- 9.1Rate laws and order: integrated rate equations, half-life, reversible, parallel and consecutive reactionsChemical kinetics · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 25 PYQ parts, 211 marks (2021–2025)CSEIFoSGeo Mains
- 9.2Theories of reaction rate: Arrhenius, collision and transition-state theoryChemical kinetics · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 21 PYQ parts, 190 marks (2021–2025)CSEIFoSGeo Mains
- 10.1Photochemistry: quantum yield, Jablonski diagram, H₂–halogen reactionsPhotochemistry · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 40 PYQ parts, 320 marks (2021–2025)CSEIFoSGeo Mains
- 11.2Adsorption, heterogeneous catalysis and colloidsSurface chemistry · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper II · 25 PYQ parts, 218 marks (2021–2025)CSEIFoSGeo Mains
Inorganic chemistry 17 topics
- 2.2VSEPR, hybridisation and Bent's ruleChemical bonding · Civil Services Paper I, IFoS Paper I, Geo-Scientist Prelims · 14 Mains parts, 134 marks (2021–2025) and 21 Prelims questionsCSEIFoSGeo PrelimsGeo Mains
- 2.11Molecular orbital theory: LCAO, homonuclear and heteronuclear diatomics (O₂, N₂, CO, NO, CN⁻, HF), bond order and magnetismChemical bonding · Civil Services Paper I, IFoS Paper I · 9 PYQ parts, 100 marks (2021–2025)CSEIFoS
- 3.3Inorganic solids: perovskite, spinel, ReO₃, corundum and high-Tc superconductorsInorganic solids · Geo-Scientist Paper I, IFoS Paper I · 11 PYQ parts, 87 marks (2021–2025)IFoSGeo Mains
- 3.4Ionic bonding: lattice energy, Born–Haber cycle, Born–Landé and Kapustinskii equations, Fajans’ rulesIonic bonding · Civil Services Paper I, IFoS Paper I · 6 PYQ parts, 46 marks (2021–2025)CSEIFoS
- 12.2Bio-inorganic chemistry: haemoglobin, cytochromes, Fe–S proteinsBio-inorganic chemistry · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper I · 21 PYQ parts, 231 marks (2021–2025)CSEIFoSGeo Mains
- 13.2Crystal field theoryCoordination chemistry · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper I · 28 PYQ parts, 255 marks (2021–2025)CSEIFoSGeo Mains
- 13.3Werner theory, isomerism, IUPAC names and VBT of complexesCoordination chemistry · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper I · 21 PYQ parts, 187 marks (2021–2025)CSEIFoSGeo Mains
- 13.4Organometallics: 18-electron rule, oxidative addition, Wilkinson's catalystOrganometallics · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper I · 19 PYQ parts, 180 marks (2021–2025)CSEIFoSGeo Mains
- 13.5Metal carbonyls, nitrosyls, 18-electron rule and metal clustersMetal carbonyls and clusters · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper I · 26 PYQ parts, 244 marks (2021–2025)CSEIFoSGeo Mains
- 13.6Substitution in complexes: labile and inert, trans effect, stability constantsReaction mechanisms of complexes · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper I · 14 PYQ parts, 120 marks (2021–2025)CSEIFoSGeo Mains
- 13.7Electronic spectra of complexes: term symbols, selection rules, charge transferElectronic spectra of complexes · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper I · 10 PYQ parts, 88 marks (2021–2025)CSEIFoSGeo Mains
- 14.1Periodic properties: Slater's rules, radii, ionisation and electron-gain enthalpy, electronegativityInorganic chemistry · Geo-Scientist Paper I, IFoS Paper I · 2 PYQ parts, 20 marks (2021–2025)IFoSGeo Mains
- 14.2Non-aqueous solvents: liquid NH₃, HF, H₂SO₄, SO₂, BrF₃ and superacidsNon-aqueous solvents · IFoS Paper I, Civil Services Paper I · 11 PYQ parts, 92 marks (2021–2025)CSEIFoS
- 14.3Transition elements: 3d, 4d and 5d compared (radii, oxidation states, redox)d-block elements · Geo-Scientist Paper I, IFoS Paper I · 8 PYQ parts, 65 marks (2021–2025)IFoSGeo Mains
- 14.4Main group chemistry: boranes, borazine, phosphazenes, silicates, silicones, interhalogens, xenon and S–N compoundsMain group chemistry · Civil Services Paper I, Geo-Scientist Paper I · 16 PYQ parts, 145 marks (2021–2025)CSEGeo Mains
- 15.1Lanthanides and actinides: contraction, magnetism, spectra, separationf-block elements · Civil Services Paper I, IFoS Paper I, Geo-Scientist Paper I · 27 PYQ parts, 261 marks (2021–2025)CSEIFoSGeo Mains
- 16.1Nuclear chemistry: decay, binding energy and the GM counterNuclear chemistry · Geo-Scientist Paper I · 23 PYQ parts, 200 marks (2021–2025)Geo Mains
Organic chemistry 15 topics
- 2.1Aromaticity: Hückel rule, antiaromaticity, annulenes, azulene, tropolone, fulvene, sydnonesDelocalised covalent bonding · Civil Services Paper II, IFoS Paper II · 18 PYQ parts, 110 marks (2021–2025)CSEIFoS
- 2.3Reactive intermediates: carbocations, carbanions, radicals, carbenes, nitrenes, benzyneReaction mechanisms · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 30 PYQ parts, 203 marks (2021–2025)CSEIFoSGeo PrelimsGeo Mains
- 2.4Addition to C=C and C≡C: Markovnikov, stereochemistry, dienesAddition reactions · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 35 PYQ parts, 196 marks (2021–2025)CSEIFoSGeo PrelimsGeo Mains
- 2.5Aromatic substitution: electrophilic, nucleophilic and heterocyclesSubstitution reactions · Civil Services Paper II, IFoS Paper II, Geo-Scientist Prelims · 27 PYQ parts, 180 marks (2021–2025) + 13 PrelimsCSEIFoSGeo Prelims
- 2.6Molecular rearrangementsReaction mechanisms · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 34 PYQ parts, 265 marks (2021–2025)CSEIFoSGeo Mains
- 2.7Methods of studying reaction mechanisms: isotopes, crossover, trapping, kinetic isotope effectReaction mechanisms · Civil Services Paper II, IFoS Paper II · 15 PYQ parts, 100 marks (2021–2025)CSEIFoS
- 2.8Aliphatic nucleophilic substitution: SN1, SN2, SNi and neighbouring group participationSubstitution reactions · Civil Services Paper II, IFoS Paper II · 21 PYQ parts, 155 marks (2021–2025)CSEIFoS
- 2.9Elimination reactions: E1, E2, E1cB, Saytzeff and Hofmann orientation, syn eliminationsElimination reactions · Civil Services Paper II, IFoS Paper II · 19 PYQ parts, 150 marks (2021–2025)CSEIFoS
- 2.10Stereochemistry and conformational analysis: R/S, E/Z, Fischer and Newman projections, cyclohexaneStereochemistry · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 16 PYQ parts, 128 marks (2021–2025)CSEIFoSGeo Mains
- 7.1Carbonyl additions and condensationsChemistry and mechanism of reactions · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 60 PYQ parts, 451 marks (2021–2025), plus PrelimsCSEIFoSGeo PrelimsGeo Mains
- 8.1Pericyclic reactionsCivil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 59 PYQ parts, 425 marks (2021–2025), the most asked organic topicCSEIFoSGeo PrelimsGeo Mains
- 9.1Polymers: polymerisation, Ziegler–Natta and molar massPolymers · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 36 PYQ parts, 240 marks (2021–2025)CSEIFoSGeo PrelimsGeo Mains
- 10.1Biopolymers: proteins, peptides, DNA and RNABiopolymers · Civil Services Paper II, IFoS Paper II · 18 PYQ parts, 135 marks (2021–2025)CSEIFoS
- 11.1Reagents for oxidation, reduction and hydroborationSynthetic uses of reagents · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 56 PYQ parts, 448 marks (2021–2025), plus PrelimsCSEIFoSGeo PrelimsGeo Mains
- 12.1Organic photochemistry: Norrish reactionsPhotochemistry · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 37 PYQ parts, 251 marks (2021–2025)CSEIFoSGeo Mains
Spectroscopy 8 topics
- 13.1UV spectroscopy and Woodward–Fieser rulesSpectroscopy · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 25 PYQ parts, 172 marks (2021–2025)CSEIFoSGeo Mains
- 13.2Infrared spectroscopy: group frequencies, carbonyl stretching and hydrogen bondingSpectroscopy · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 24 PYQ parts, 163 marks (2021–2025)CSEIFoSGeo Mains
- 13.3¹H and ¹³C NMR: chemical shift, spin–spin coupling and coupling constantsSpectroscopy · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 30 PYQ parts, 192 marks (2021–2025)CSEIFoSGeo Mains
- 13.4Mass spectrometry: molecular ion, metastable peak and McLafferty rearrangementSpectroscopy · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 26 PYQ parts, 166 marks (2021–2025)CSEIFoSGeo Mains
- 13.5Structure from combined spectra: IR, NMR and massSpectroscopy · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper III · 26 PYQ parts, 253 marks (2021–2025)CSEIFoSGeo Mains
- 13.6Rotational (microwave) and Raman spectraSpectroscopy · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper II · 26 PYQ parts, 170 marks (2021–2025)CSEIFoSGeo Mains
- 13.7Vibrational and electronic spectra: anharmonicity and Franck–CondonSpectroscopy · Civil Services Paper II, IFoS Paper II, Geo-Scientist Paper II · 19 PYQ parts, 140 marks (2021–2025)CSEIFoSGeo Mains
- 13.10ESR (EPR) spectroscopy: g-value, hyperfine splitting, radical anions, metal ions and spin labelsSpectroscopy · IFoS Paper II · 5 PYQ parts, 25 marks (2021–2025)IFoS
Analytical chemistry 10 topics
- 13.8Spectroscopic instruments: UV–vis, IR, Beer–Lambert, AAS and flame emissionAnalytical chemistry · Geo-Scientist Paper III · 28 PYQ parts, 220 marks (2021–2025)Geo Mains
- 13.9X-ray methods (XRD, XRF) and ICP-OES / ICP-MSAnalytical chemistry · Geo-Scientist Paper III · 22 PYQ parts, 175 marks (2021–2025)Geo Mains
- 17.1Acid–base titrations: curves, indicators, buffersAnalytical chemistry · Geo-Scientist Paper I (and Paper II) · 20 PYQ parts, 195 marks (2021–2025)Geo Mains
- 17.2Redox titrations: equivalence potential, indicators, iodometryAnalytical chemistry · Geo-Scientist Paper I (and Paper II) · 20 PYQ parts, 190 marks (2021–2025)Geo Mains
- 17.3Complexometric (EDTA) titrations: conditional constants, indicators, maskingAnalytical chemistry · Geo-Scientist Paper I · 18 PYQ parts, 170 marks (2021–2025)Geo Mains
- 17.4Gravimetric analysis: solubility product, precipitation, co-precipitation, organic precipitantsAnalytical chemistry · Geo-Scientist Paper I · 19 PYQ parts, 160 marks (2021–2025)Geo Mains
- 17.5Errors in chemical analysis: accuracy, precision, standard deviation, Q-test, t-test, F-testAnalytical chemistry · Geo-Scientist Paper III · 11 PYQ parts, 75 marks (2021–2025)Geo Mains
- 17.6Chromatography (HPLC, GLC, TLC, ion exchange) and solvent extractionAnalytical chemistry · Geo-Scientist Paper III · 15 PYQ parts, 125 marks (2021–2025)Geo Mains
- 17.7Analysis of ores, alloys, petroleum, coal and cokeAnalytical chemistry · Geo-Scientist Paper III · 19 PYQ parts, 140 marks (2021–2025)Geo Mains
- 17.8Thermal methods: thermogravimetry (TG), DTG and DTA, with Ca and Mg analysisAnalytical chemistry · Geo-Scientist Paper III · 10 PYQ parts, 65 marks (2021–2025)Geo Mains
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Looking for one exam only? Each paper's Notes page lists the topics of its syllabus: Civil Services Paper I · Civil Services Paper II · IFoS Paper I · IFoS Paper II · Geo-Scientist Paper I · Geo-Scientist Paper II · Geo-Scientist Paper III.