UPSC: Chemistry Optional Syllabus for UPSC involves core chemistry topics and the syllabus is suitable for candidates who have studied Chemistry at the graduate level. The syllabus of the Chemistry Optional exam focuses on the atomic structure, states of matter, different kinds of reactions among others. It is recommended that candidates should primarily be thorough with the syllabus before choosing any optional.

In this article, you will read all about the chemistry optional for the IAS mains exam – strategy for both papers, syllabus, toppers, etc.

How many take Chemistry optional-?

The number of candidates who opt for chemistry as their optional is not very high unlike subjects like pub ad or geography. But on an average, anywhere between 70 and 120 people take up this optional. In 2016, as per the latest available data, 124 candidates had taken chemistry out of which only 7 made it.

Chemistry optional pros and cons

There are advantages and disadvantages in taking a core science subject like chemistry as the optional in the IAS mains. Some of the major points are discussed below.

Chemistry optional pros

Science subject

Chemistry is considered a scoring subject as it is a precise science unlike the humanities or social sciences. The concepts cannot be interpreted in multiple ways and nothing is subjective. This makes the marking more predictable.

Scoring subject

Chemistry is a scoring subject because there is ample scope for diagrams and equations. You also have numericals in this paper which when done correctly can fetch you maximum marks for the question. Additionally, with conceptual clarity, you can write good answers and get high marks. Many candidates have secured 300+ in this optional which is very rare in humanities optionals.

Static portions

Most of the syllabus is entirely static.

Less competition

Because of the less number of candidates who opt for this optional, the competition you will face with this optional is quite less.

Overlap

There is a minor overlap with GS papers particularly in topics such as environment, climate change, new scientific technologies like nanotechnology, fibre optics, etc.

Chemistry optional cons

You should have a background in chemistry if you wish to take up this optional.

You should genuinely have an interest in reading chemistry otherwise it would be very difficult to complete the syllabus.

The syllabus will take at least 6 months to complete.

There is very little overlap with the general studies papers.

You have to write precise answers as it is a core science subject. You cannot beat about the bush in any answer and hope to get minimum marks.

Chemistry optional syllabus

Let us take a look at the syllabus for chemistry for the UPSC mains exam.

There are two optional papers in the UPSC exam pattern. Both the papers are for a total of 250 marks making the total optional marks to 500.

Download the Chemistry syllabus PDF.-SubodhCheM

Chemistry optional strategy

General tips for chemistry optional

The most important step in your chemistry optional preparation is to be well-versed with the syllabus. Have a copy of the UPSC syllabus for chemistry optional ready by your side always.

Before you start the detailed topic-wise preparation of this subject, you must be prepared with the basics first. For this, you can start with the XI and XII NCERT textbooks of chemistry. This is especially for those candidates who have had lost their touch with the subject.

Go through the previous years’ UPSC question papers and understand what are the portions of the syllabus from where questions are asked repeatedly. It is advisable that you complete the entire syllabus, but, this exercise will help you know which portions can be given more importance.

Make short notes and mnemonics to remember certain things like the periodic table, etc.

Regular revision is extremely important in a paper like chemistry. There are a lot of theories, concepts, equations, etc. to study.

Numericals are tricky. In case you present the correct answer with sufficient background theory, you may get full marks for the question. But if the answer is incorrect, you may lose the entire marks.

In the next section, we discuss topic-wise preparation strategy for chemistry optional.

Chemistry paper I

Atomic structure – this is a relatively easy topic. There are some basic concepts. You can refer to ‘Principles of Physical Chemistry’ by Puri, Sharma & Pathania for this section. Do go through the previous question papers for this section.

Chemical bonding – this is the most important topic in this paper. For this section, you can read Physical Chemistry by KL Kapoor. Stick to the syllabus because this is a very vast topic which involves high level of mathematics (which is not at all relevant for UPSC). Some problematic topics in this section are molecular orbital theory and valence bond theory and their mathematical aspects. To tackle these, go through previous question papers and try to find out the answers from KL Kapoor, this would be sufficient.

Example question:

What is an orbital and how is it related to probability density? (5 marks, 2018)

Determine the geometry of [Ni(H2O)6]2+ (paramagnetic complex with two unpaired electrons) using valence bond theory. (5 marks, 2018)

Point out the main features of the Valence Bond and Molecular Orbital theories. For the H2 molecule, write down the wave function using: (10 marks, 2014)

(i) Valence Bond Theory

(ii) Molecular Orbital Theory

3. Solid state – this is an easy topic and KL Kapoor would be enough for it. You can also refer to the NCERTs for this section as it explains the concepts in a simple manner.

4. Gaseous State and Transport Phenomenon – this is also an easy chapter and the UPSC has always asked very basic questions from here. The most important source for this section is Puri, Sharma and Pathania. In this section, collision theory is very important and even numericals are asked from this.

5. Liquid State – you can easily do it from KL Kapoor.

6. Thermodynamics – for this section, you can refer to Puri, Sharma and Pathania. Again, only basic questions are asked.

Example question:

At constant pressure, the temperature of a fixed amount of hot tea in a cup decreases spontaneously to room temperature. What will be the sign of (I) ΔH and (II) ΔG of this process? Give reasons in support of your answer. (10 marks, 2018)

7. Phase Equilibria and Solutions – many candidates tend to ignore this section. That would be a mistake.

8. Electrochemistry – this is a very vast portion of the syllabus. You can refer to Puri, Sharma and Pathania or KL Kapoor for this section.

9. Chemical Kinetics – this section is generally easy. Sometimes, numericals are asked from the activation energy topic. Any basic book will cover this section.

Example question:

What are the characteristics, essential for catalysis with specific reference to surface catalysis? (10 marks, 2018)

Define activation energy, Ea of a chemical reaction. A gas-phase reaction completes 25% in 30 min at 27oC and in 10 min at 37oC. Determine the Ea in SI unit. (15 marks, 2018)

10. Photochemistry – this is largely based on chemical kinetics section. Even though not mentioned explicitly in the syllabus, do read Grotthuss–Draper law and Einstein’s law. Questions have been asked from these topics.

11. Surface Phenomena and Catalysis – you should study the derivations of all the theories here. You can refer to either KL Kapoor or Puri, Sharma and Pathania.

The above sections dealt with physical chemistry. The following deals with inorganic chemistry.

12. Bio-inorganic Chemistry – you can refer to Inorganic Chemistry by James Huheey. This is a very important book for entire inorganic chemistry.

13. Coordination Compounds – Huheey is sufficient for this topic.

Example questions:

What is meant by EAN rule applied to complexes? Apply the concept of EAN rule on the following two complexes [Fe(CN)6]4- and [Fe(CN)6]3- and draw your conclusion about the validity of the rule. (10 marks, 2017)

14. Main Group Chemistry – for this section, NCERTs and Huheey are important.

15. General Chemistry of ‘f’ Block Elements – Huheey is sufficient for this topic.

Chemistry Paper II

Paper II deals with organic chemistry. This is a crucial section because with a little extra practice and conceptual clarity, you can score high marks.

Delocalised Covalent Bonding – you can refer to Peter Sykes for Organic Chemistry.

Reaction Mechanisms – this is a very important chapter in organic chemistry. In fact, it is very important to understand this concept as many topics are related to this. Peter Sykes is a good reference book for this topic.

In rearrangements and named reactions, you must focus on why the reaction is happening. Understand every step of the reaction. This will help you answer questions on them. You must literally mug up the named reactions for the exam.

Example questions:

With suitable example, comment whether Fries Rearrangement proceeds intermolecularly or intramolecularly. Give evidence in favour of your answer. (5 marks, 2018)

3. Pericyclic Reactions – you can refer to Organic Chemistry by Clayden or Peter Sykes for this topic.

4. Polymers – questions are asked every year from this section. Do not leave any topic from here.

Example questions:

Give the synthetic schemes including reaction conditions for the preparation of the following polymers from their monomers: (15 marks, 2018)

(i) Nylon 66

(ii) Teflon

(iii) Terylene

Distinguish between RNA and DNA with regard to their nucleotide structures, location in the cells and functions. (10 marks, 2018)

5. Synthetic Uses of Reagents – this is a very easy and scoring section. Questions are asked every year mostly.

6. Photochemistry – you must practice questions for this section specifically. This is tricky as it deals with free radicals and they can react anytime with anything! But, practice should help you here, and also the UPSC does not ask very vague questions from here. Photochemistry and Pericyclic Reactions by Jagdamba Singh is good for this.

7. Spectroscopy – refer to previous question papers to understand the type of questions asked from here. The book recommended for this is Spectroscopy of Organic Compounds by PS Kalsi. Here, some question types that are repeated are to calculate the lambda max, mass spectra, NMR (structure and signals), and IR spectra reasoning.

Chemistry optional books

Principles of Physical Chemistry by Puri, Sharma & Pathania

Physical Chemistry by KL Kapoor/PSP/ATKINS/MCQ/R.K.PRASAD

Inorganic Chemistry by James Huheey/JD LEE/HOUSE CRAFT/MASSLAR TARR

Organic Chemistry by Peter Sykes

Organic Chemistry by Clayden/M.CARRUTHER/M.NANTZ/J SANDBURG

Photochemistry and Pericyclic Reactions by Jagdamba Singh

An Introduction to Electrochemistry by Samuel Glasstone/ATKINS

Concise Inorganic Chemistry by J.D. Lee

Spectroscopy of Organic Compounds by PS Kalsi/PAVIA/C.N.BANEWELL

NCERT textbooks of classes XI and XII for Chemistry/12TH-O.P.TONDON-/O.P.AGRAWAL/INORGANIC/ORGANIC/PHYSICAL

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UPSC Optional Syllabus for Chemistry- Paper I 

1-Atomic Structure:

Heisenberg's uncertainty principle, Schrodinger wave equation (time-independent); 

Interpretation of wave function, particle in one-dimensional box, quantum numbers, hydrogen atom wave functions; Shapes of s, p and d orbitals.

2-Chemical Bonding:

Ionic bond, characteristics of ionic compounds, lattice energy, Born-Haber cycle; covalent bond and its general characteristics, polarities of bonds in molecules and their dipole moments; 

Valence bond theory, concept of resonance and resonance energy; Molecular orbital theory (LCAO method); bonding in H2+, H2, He2+ to Ne2, NO, CO, HF, and CN-;

Comparison of valence bond and molecular orbital theories, bond order, bond strength and bond length.

3-Solid State: 

Crystal systems; Designation of crystal faces, lattice structures and unit cell; Bragg's law; 

X-ray diffraction by crystals; Close packing, radius ratio rules, calculation of some limiting radius ratio values; 

Structures of NaCl, ZnS, CsCl and CaF2; Stoichiometric and nonstoichiometric defects, impurity defects, semi-conductors.

The Gaseous State and Transport Phenomenon: 

Equation of state for real gases, intermolecular interactions and critical phenomena and liquefaction of gases, Maxwell's distribution of speeds, intermolecular collisions, collisions on the wall and effusion; 

Thermal conductivity and viscosity of ideal gases.

Liquid State: 

Kelvin equation; Surface tension and surface energy, wetting and contact angle, interfacial tension and capillary action.

Thermodynamics: Work, heat and internal energy; first law of thermodynamics. Second law of thermodynamics; entropy as a state function, entropy changes in various processes, entropy-reversibility and irreversibility, Free energy functions; Thermodynamic equation of state; Maxwell relations; Temperature, volume and pressure dependence of U, H, A, G, Cp and Cv α and β; J-T effect and inversion temperature; criteria for equilibrium, relation between equilibrium constant and thermodynamic quantities; Nerns theat theorem, introductory idea of third law of thermodynamics.

Phase Equilibria and Solutions: 

Clausius-Clapeyron equation; phase diagram for a pure substance; phase equilibria in binary systems, partially miscible liquids-upper and lower critical solution temperatures; partial molar quantities, their significance and determination; excess thermodynamic functions and their determination.

Electrochemistry: 

Debye-Huckel theory of strong electrolytes and Debye-Huckel limiting Law for various equilibrium and transport properties. Galvanic cells, concentration cells; electrochemical series, measurement of e.m.f. of cells and its applications fuel cells and batteries. Processes at electrodes; double layer at the interface; rate of charge transfer, current density; overpotential; electro-analytical techniques: Polarography, amperometry, ion selective electrodes and their uses.

Chemical Kinetics:

Differential and integral rate equations for zeroth, first, second and fractional order reactions; Rate equations involving reverse, parallel, consecutive and chain reactions; branching chain and explosions; 

effect of temperature and pressure on rate constant; Study of fast reactions by stop-flow and relaxation methods; Collisions and transition state theories.

Photochemistry:

Absorption of light; decay of excited state by different routes; photochemical reactions between hydrogen and halogens and their quantum yields.Surface Phenomena and Catalysis:Absorption from gases and solutions on solid adsorbents, Langmuir and B.E.T. adsorption isotherms; determination of surface area, characteristics and mechanism of reaction on heterogeneous catalysts.

Bio-inorganic Chemistry:

Metal ions in biological systems and their role in ion transport across the membranes (molecular mechanism), oxygenuptake proteins, cytochromes and ferredoxins.

Coordination Compounds:

(i) Bonding theories of metal complexes; Valence bond theory, crystal field theory and its modifications; applications of theories in the explanation of magnetism and electronic spectra of metal complexes. 

(ii) Isomerism in coordination compounds; IUPAC nomenclature of coordination compounds; stereochemistry of complexes with 4 and 6 coordination numbers; chelate effect and polynuclear complexes; trans effect and its theories; kinetics of substitution reactions in square-planer complexes; thermodynamic and kinetic stability of complexes. 

(iii) EAN rule, Synthesis structure and reactivity of metal carbonyls; carboxylate anions, carbonyl hydrides and metal nitrosyl compounds. 

(iv) Complexes with aromatic systems, synthesis, structure and bonding in metal olefin complexes, alkyne complexes and cyclopentadienyl complexes; coordinative unsaturation, oxidative addition reactions, insertion reactions, fluxional molecules and their characterization; Compounds with metal-metal bonds and metal atom clusters.

Main Group Chemistry: 

Boranes, borazines, phosphazenes and cyclic phosphazene, silicates and silicones, Interhalogen compounds; Sulphur - nitrogen compounds, noble gas compounds.

General Chemistry of 'f' Block Elements: 

Lanthanides and actinides; separation, oxidation states, magnetic and spectral properties; lanthanide contraction.

UPSC Optional Syllabus for Chemistry- Paper --II

Delocalised Covalent Bonding:

Aromaticity, anti-aromaticity; annulenes, azulenes, tropolones, fulvenes, sydnones.

 (i) Reaction Mechanisms: General methods (both kinetic and non-kinetic) of study of mechanism of organic reactions: isotopic method, cross-over experiment, intermediate trapping, stereochemistry; energy of activation; thermodynamic control and kinetic control of reactions.

(ii) Reactive Intermediates: Generation, geometry, stability and reactions of carbonium ions and carbanions, free radicals, carbenes, benzynes and nitrenes.

(iii) Substitution Reactions: SN1, SN2 and SNi mechanisms; neighbouring group participation; electrophilic and nucleophilic reactions of aromatic compounds including heterocyclic compounds-pyrrole, furan, thiophene and indole.

(iv) Elimination Reactions: E1, E2 and E1cb mechanisms; orientation in E2 reactions-Saytzeff and Hoffmann; pyrolytic syn elimination - Chugaev and Cope eliminations.

(v) Addition Reactions: Electrophilic addition to C=C and C=C; nucleophilic addition to C=0, C=N, conjugated olefins and carbonyls.

(vi) Reactions and Rearrangements:

(a) Pinacol-pinacolone, Hoffmann, Beckmann, Baeyer-Villiger, Favorskii, Fries, Claisen, Cope, Stevens and WagnerMeerwein rearrangements.

(b) Aldol condensation, Claisen condensation, Dieckmann, Perkin, Knoevenagel, Witting, Clemmensen, Wolff-Kishner, Cannizzaro and von Richter reactions; Stobbe, benzoin and acyloin condensations; Fischer indole synthesis, Skraup synthesis, Bischler-Napieralski, Sandmeyer, Reimer-Tiemann and Reformatsky reactions.

Pericyclic Reactions:

Classification and examples; 

Woodward Hoffmann rules - electro cyclic reactions, cycloaddition reactions [2+2 and 4+2] and sigma tropic shifts [1, 3; 3, 3 and 1, 5] FMO approach.

(i) Preparation and Properties of Polymers: Organic polymers-polyethylene, polystyrene, polyvinyl chloride, teflon, nylon, terylene, synthetic and natural rubber.

(ii) Biopolymers: Structure of proteins, DNA and RNA.

Synthetic Uses of Reagents: 

OsO4, HIO4, CrO3, Pb(OAc)4, SeO2, NBS, B2H6, Na-Liquid NH3, LiAlH4, NaBH4, n-BuLi and MCPBA.

Photochemistry: 

Photochemical reactions of simple organic compounds, excited and ground states, singlet and triplet states, Norrish-Type I and Type II reactions.

Spectroscopy: Principle and applications in structure elucidation: 

(i) Rotational: Diatomic molecules; isotopic substitution and rotational constants.

(ii) Vibrational: Diatomic molecules, linear triatomic molecules, specific frequencies of functional groups in polyatomic molecules.

(iii) Electronic: Singlet and triplet states; N→π* and ππ*→ transitions; application to conjugated double bonds and conjugated carbonyls-Woodward-Fieser rules; Charge transfer spectra.

(iv) Nuclear Magnetic Resonance (1H NMR): Basic principle; chemical shift and spin-spin interaction and coupling constants.

(v) Mass Spectrometry: Parent peak, base peak, metastable peak, McLafferty rearrangement.