AIIMS Chemistry Syllabus 2025 – Detailed Chapters & Weightage

Chapter Name

SubTopics

Some Basic Concepts in Chemistry

• Matter and its Nature

• Laws of chemical combination, Dalton’s atomic theory: concept of elements, atoms and molecules.

• Atomic and molecular masses. Mole concept and molar mass; percentage composition and empirical and molecular formula; chemical reactions, stoichiometry.

Atomic Structure

• Nature of electromagnetic radiation, photoelectric effect; Spectrum of the hydrogen atom.

• Bohr model of a hydrogen atom - its postulates, derivation of the relations for the energy of the electron and radii of the different orbits, limitations of Bohr's model;

• Dual nature of matter, de Broglie's relationship. Heisenberg uncertainty principle. Elementary ideas of quantum mechanics, quantum mechanics, the quantum mechanical model of the atom, its important features.

• Concept of atomic orbitals as one-electron wave functions: Variation of Ψ and Ψ 2 with r for 1s and 2s orbitals: various quantum numbers (principal, angular momentum, and magnetic quantum numbers) and their significance; shapes of s, p, and d - orbitals, electron spin and spin quantum number:

• Rules for filling electrons in orbits - Aufbau principle. Pauli's exclusion principle and Hund's rule, electronic configuration of elements, and extra stability of half-filled and completely filled orbitals.

Chemical Bonding and Molecular Structure

• Kossel - Lewis approach to chemical bond formation, the concept of ionic and covalent bonds.

• Ionic Bonding: Formation of ionic bonds, factors affecting the formation of ionic bonds; calculation of lattice enthalpy.

• Covalent Bonding: Concept of electronegativity. Fajan's rule, dipole moment: Valence Shell Electron Pair Repulsion (VSEPR) theory and shapes of simple molecules.

• Quantum mechanical approach to covalent bonding: Valence bond theory - its important features. the concept of hybridisation involving s, p, and d orbitals; Resonance.

• Molecular orbital Theory - Its important features. LCAOs, types of molecular orbitals (bonding, antibonding), sigma and pi-bonds, molecular orbital electronic configurations of homonuclear diatomic molecules, the concept of bond order, bond length, and bond energy.

• Elementary idea of metallic bonding. Hydrogen bonding and its applications.

Chemical Thermodynamics

• Fundamentals of thermodynamics: System and surroundings, extensive and intensive properties' state functions, types of processes.

• The First Law of Thermodynamics - Concept of work, heat internal energy and enthalpy, heat capacity, molar heat capacity; Hess's law of constant heat summation; Enthalpies of bond dissociation, combustion' formation, atomisation. sublimation. phase transition, hydration. ionisation. and solution.

• The Second Law of Thermodynamics - Spontaneity of processes: S of the universe and of the system as criteria for spontaneity. Standard Gibbs energy change and equilibrium constant.

Solutions

• Different methods for expressing the concentration of solution - molality, molarity, mole fraction. percentage (by volume and mass), the vapor pressure of solutions and Raoult's law - Ideal and non-ideal solutions.

• vapour pressure - composition, plots for ideal and non-ideal solutions: colligative properties of dilute solutions - a relative lowering of vapour pressure, depression of freezing point, the elevation of boiling point and osmotic pressure

• Determination of molecular mass using colligative properties; Abnormal value of molar mass, Van't Hoff Factor and its significance.

Equilibrium

• Meaning of equilibrium, the concept of dynamic equilibrium.

• Equilibria involving physical processes: Solid-liquid, liquid - gas and solid-gas equilibria, Henry's law. General characteristics of equilibrium involving physical processes.

• Equilibrium involving chemical processes: Law of chemical equilibrium, equilibrium constants (Kp and Kc) and their significance, the significance of ΔG and ΔG° in chemical equilibrium, factors affecting equilibrium concentration, pressure, temperature, the effect of catalyst; Le Chatelier's principle.

• Ionic equilibrium: weak. and strong electrolytes, ionisation of electrolytes, various concepts of acids and bases (Arrhenius and Bronsted - Lowry and Lewis) and their ionisation, acid-base equilibria (including multi stage ionisation) and ionisation constants, ionisation of water. 

• PH scale, common ion effect, hydrolysis of salts and PH of their solutions, the solubility of sparingly soluble salts and solubility products, buffer solutions.

Redox Reaction and ElectroChemistry

• Electronic concepts of oxidation reduction, redox reactions, oxidation numbers, rules for assigning oxidation number, balancing of redox reactions.

• Electrolytic and metallic conduction, conductance in electrolytic solutions, molar conductivities and their variation with concentration, Kohlrausch's law and its applications.

• Electrochemical Cells - Electrolytic and Galvanic cells, different types of electrodes, electrode potentials including standard electrode potential, half-cell and cell reactions, emf of a Galvanic cell and its measurement: Nernst equation and its applications; Relationship between cell potential and Gibbs' energy change: Dry cell and lead accumulator; Fuel cells.

Chemical Kinetics

• Rate of a chemical reaction, factors affecting the rate of reactions: concentration, temperature, pressure and catalyst; elementary and complex reactions order and molecularity of reactions

• Rate law, rate constants and its units, differential and integral forms of zero and first-order reactions, their characteristics and half-lives, the effect of temperature on the rate of reactions, Arrhenius theory, activation energy and its calculation, collision theory of bimolecular gaseous reactions (no derivation)

Chapter Name

SubTopics

Classification of Elements and Periodicity in Properties

• Modern periodic law and present form of periodic table, s, p, d and f block elements, periodic trends in properties of elements atomic and ionic radii

• Ionisation enthalpy, electron gain enthalpy, valence, oxidation states, and chemical reactivity.

p-block Elements

• Group 13 to Group 18 Elements

• General Introduction: Electronic configuration and general trends in physical and chemical properties of elements across the periods and down the groups.

• unique behavior of the first element in each group.

d- and f-block Elements

Transition Elements

• General introduction, electronic configuration, occurrence and characteristics, general trends in properties, of the first-row transition elements - physical properties, ionisation enthalpy, oxidation states, atomic radii, colour, catalytic behaviour, magnetic properties, complex formation, interstitial compounds, alloy formation; Preparation, properties and uses of $K_2​Cr_2​O_7$​ and $KMnO_4$

• Inner Transition Elements

Lanthanoids - Electronic configuration, oxidation states, and lanthanoid contraction.

Actinoids - Electronic configuration and oxidation states.

Coordination Compounds

• Introduction to coordination compounds Werner's theory; ligands, coordination number. denticity. chelation; IUPAC nomenclature of mononuclear coordination compounds, isomerism

• Bonding-Valence bond approach and basic ideas of Crystal field theory, colour and magnetic properties;the  importance of coordination compounds (in qualitative analysis. extraction of metals and in biological systems.

Chapter Name

SubTopics

Purification and Characterisation of Organic Compounds

• Purification - Crystallisation. sublimation, distillation, differential extraction, chromatography - principles and their applications.

• Qualitative analysis - Detection of nitrogen, sulphur, phosphorus and halogens.

• Quantitative analysis (basic principles only) - Estimation of carbon, hydrogen, nitrogen, halogens, sulphur, and phosphorus.

• Calculations of empirical formula and molecular formulae: Numerical problems in organic quantitative analysis.

Some Basic Principles of Organic Chemistry

• Tetravalency of carbon: Shapes of simple molecules - hybridisation (s and p): classification of organic compounds based on functional groups: and those containing halogens, oxygen, nitrogen and sulphur; Homologous series: Isomerism - structural and stereoisomerism.

• Nomenclature (Trivial and IUPAC) - Covalent bond fission - Homolytic and heterolytic: free radicals. carbocations. and carbanions: stability of carbocations and free radicals. electrophiles. and nucleophiles.

• Electronic displacement in a covalent bond- Inductive effect, electromeric effect. resonance and hyperconjugation.Common types of organic reactions- Substitution. addition. elimination, and rearrangement.

Hydrocarbons

• Classification, isomerism. IUPAC nomenclature, general methods of preparation, properties, and reactions.

Alkanes - Conformations: Sawhorse and Newman projections (of ethane): Mechanism of halogenation of alkanes, projections (of ethane).

Alkenes - Geometrical isomerism: Mechanism of electrophilic addition: addition of hydrogen. halogens, water. hydrogen halides (Markownikoffs and peroxide effect): Ozonolysis and polymerisation.

Alkynes - Acidic character: Addition of hydrogen, halogens, water, and hydrogen halides: Polymerisation.

• Aromatic hydrocarbons - Nomenclature. benzene - structure and aromaticity: Mechanism of substitution: halogenation, nitration.

Friedel-Crafts alkylation and acylation, directive influence of the functional group in mono-substituted benzene.

Organic Compounds Containing Halogens

• General methods of preparation, properties, and reactions; Nature of C-X bond: Mechanisms of substitution reactions

Uses; Environmental effects of chloroform, iodoform freons, and DDT

Organic Compounds Containing Oxygen

• General methods of preparation, properties, reactions, and uses.

Alcohols: Identification of primary, secondary, and tertiary alcohols: mechanism of dehydration.

• Phenols - Acidic nature, electrophilic substitution reactions: halogenation. nitration and sulphonation. Reimer - Tiemann reaction.

• Ethers: Structure.

• Aldehyde and Ketones - Nature of carbonyl group; Nucleophilic addition to >C=O group, relative reactivities of aldehydes and ketones; Important reactions such as - Nucleophilic addition reactions (addition of HCN. NH3 and its derivatives), Grignard reagent; oxidation: reduction (Wolf Kishner and Clemmensen); the acidity of α-hydrogen. aldol condensation, Cannizzaro reaction. Haloform reaction, Chemical tests to distinguish between aldehydes and Ketones.

• Carboxylic Acids - Acidic strength and factors affecting it.

Organic Compounds Containing Nitrogen

• General methods of preparation. Properties, reactions, and uses.

• Amines: Nomenclature, classification structure, basic character, and identification of primary, secondary, and tertiary amines and their basic character.

• Diazonium Salts: Importance in Synthetic Organic Chemistry.

Biomolecules

• General introduction and importance of biomolecules.

• CARBOHYDRATES - classification; aldoses and ketoses: monosaccharides (glucose and fructose) and constituent monosaccharides of oligosaccharides (sucrose, lactose, and maltose)

• PROTEINS - Elementary Idea of α-amino acids, peptide bonds, polypeptides. Proteins: primary. secondary, tertiary, and quaternary structure (qualitative idea only), denaturation of proteins enzymes.

• VITAMINS - Classification and functions

• NUCLEIC ACIDS - Chemical constitution of DNA and RNA, Biological functions of nucleic acids Hormones (General Introduction)

Principles Related to Practical Chemistry

• Detection of extra elements (Nitrogen, sulphur, halogens), in organic compounds; Detection of the following functional group, hydroxyl (alcoholic and phenolic), carbonyl (aldehyde and ketones) carboxyl, and amino groups in organic compounds.

• The Chemistry involved in the preparation of the following:

• Inorganic compounds: Mohr's salt. potash alum

• Organic compounds: Acetanilide. p-nitro acetanilide, aniline yellow, iodoform

• The Chemistry involved in the titrimetric exercises - Acids. bases and the use of indicators. oxalic-acid vs

• $KMnO_4$​. Mohr's salt vs $KMnO_4$​

• Chemical principles involved in the qualitative salt analysis:

• Cations:Pb2+,Cu2+,Al3+,Fe3+,Zn2+,Ni2+,Ca2+,Ba2+,Mg2+,NH4+

• Anions: CO32−​,S2−,SO42−​,NO3−, Cl−,Br−,I− (Insoluble salts excluded)

• Chemical principles involved in the following experiments:

• Enthalpy of solution of $CuSO_4​$

• Enthalpy of neutralization of strong acid and strong base

• Preparation of lyophilic and lyophobic sols

• Kinetic study of the reaction of iodide ions with hydrogen peroxide at room temperature.

Section

Weightage (%)

Expected No. of Questions (Out of 45)

Physical Chemistry

30%

13–14

Inorganic Chemistry

35%

15–16

Organic Chemistry

35%

15–16

S. No

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