Padikam lessons

ORIGINAL STUDY COMPANION PADIKAM CLASS 11 | SCIENCE Chemistry CBSE / NCERT core lessons | Academic year 2026-27 11 chapter lessons Quick explanations, core points, exam practice and chapter-specific notation in one consistent format. Padikam explanations are independently written. Official textbooks are used as the coverage map, chapter sequence and terminology reference. PADIKAM | CBSE NCERT CLASS 11 1

Contents 01 Some Basic Concepts of Chemistry 02 Structure of Atom 03 Classification of Elements and Periodicity 04 Chemical Bonding and Molecular Structure 05 Thermodynamics 06 Equilibrium 07 Redox Reactions 08 Organic Chemistry: Some Basic Principles and Techniques 09 Hydrocarbons 10 Formative Reading: The Gaseous State 11 Formative Reading: s- and p-Block Elements Study rhythm Read the quick explanation, recall the core points aloud, then answer the prompts without looking back. Use the official textbook links for full prescribed readings, activities and diagrams. Textbook and verification links

1. https://cbseacademic.nic.in/web_material/CurriculumMain27/SecPart2/Chemistry_SecP2_2026-27.pdf
2. https://ncert.nic.in/textbook.php
3. https://cbseacademic.nic.in/curriculum_2027.html PADIKAM | CBSE NCERT CLASS 11 2

CHAPTER 01 Some Basic Concepts of Chemistry Quick understanding Use the mole to connect microscopic particles with measurable mass, volume and concentration. Core points Check your learning Balance equations before using stoichiometric ratios. Find the empirical formula from percentage composition. The limiting reagent fixes the maximum product. Calculate limiting reagent and Keep significant figures and units through every percentage yield. step. Equation and notation n = m/M N = nN_A Molarity = moles of solute / volume of solution in L SYMBOLS AND UNITS n: amount (mol) M: molar mass (g mol⁻¹) N_A: Avogadro constant m: sample mass (g) N: number of particles Volume in molarity: litre (L) One-line recall Balance equations before using stoichiometric ratios. PADIKAM | CBSE NCERT CLASS 11 3

CHAPTER 02 Structure of Atom Quick understanding Follow atomic models from spectra to quantum numbers and electronic configuration. Core points Check your learning Orbitals are probability distributions, not fixed paths. Write quantum numbers for the last electron of an element. No two electrons in an atom share all four quantum numbers. Calculate wavelength or energy of radiation. Aufbau, Pauli and Hund rules guide configuration. Equation and notation E = hν = hc/λ λ = h/mv ΔxΔp ≥ h/4π SYMBOLS AND UNITS h: Planck constant ν: frequency (s⁻¹) λ: wavelength (m) c: speed of light (m s⁻¹) m: particle mass (kg) v: particle speed (m s⁻¹) Δx: position uncertainty (m) Δp: momentum uncertainty (kg m s⁻¹) One-line recall Orbitals are probability distributions, not fixed paths. PADIKAM | CBSE NCERT CLASS 11 4

CHAPTER 03 Classification of Elements and Periodicity Quick understanding Use electronic configuration to explain recurring trends across the periodic table. Core points Check your learning Effective nuclear charge generally increases across Compare sizes of an atom and its ions. a period. Explain an apparent exception in Atomic radius generally decreases across a period ionisation enthalpy. and increases down a group. Ionisation enthalpy, electron-gain enthalpy and electronegativity have related but distinct meanings. One-line recall Effective nuclear charge generally increases across a period. PADIKAM | CBSE NCERT CLASS 11 5

CHAPTER 04 Chemical Bonding and Molecular Structure Quick understanding Explain stability and shape through ionic, covalent and coordinate bonding, VSEPR and orbital overlap. Core points Check your learning Lewis structures track valence electrons and formal Predict shape and hybridisation of NH₃, charge. H₂O and SF₆. Lone-pair repulsion changes ideal bond angles. Calculate bond order using molecular orbitals. Hybridisation and molecular orbital theory answer different structural questions. Equation and notation Formal charge = V − L − ½B Bond order = ½(N_b − N_a) SYMBOLS AND UNITS V: valence electrons L: nonbonding electrons B: bonding electrons N_b: electrons in bonding molecular orbitals N_a: electrons in antibonding molecular orbitals Bond order and formal charge: dimensionless One-line recall Lewis structures track valence electrons and formal charge. PADIKAM | CBSE NCERT CLASS 11 6

CHAPTER 05 Thermodynamics Quick understanding Measure energy changes in chemical systems and connect enthalpy, entropy and spontaneity. Core points Check your learning State functions depend only on initial and final Use bond enthalpies to estimate ΔH. states. Predict spontaneity from ΔH and ΔS. Hess’s law follows from enthalpy being a state function. Negative Gibbs energy indicates thermodynamic possibility, not reaction speed. Equation and notation ΔU = q + w ΔH = ΔU + Δ(PV) ΔG = ΔH − TΔS SYMBOLS AND UNITS ΔH: enthalpy change (kJ mol⁻¹) ΔS: entropy change (J mol⁻¹ K⁻¹) ΔG: Gibbs energy change ΔQ or q: heat supplied to the system (J) ΔU: internal-energy change (J) ΔW or w: work (J) P: pressure (Pa) V: volume (m³) n: amount of gas (mol) R: molar gas constant (J mol⁻¹ K⁻¹) T: absolute temperature (K) Q_H: heat absorbed from hot reservoir (J) One-line recall State functions depend only on initial and final states. PADIKAM | CBSE NCERT CLASS 11 7

CHAPTER 06 Equilibrium Quick understanding Treat physical and chemical equilibria as dynamic states and predict shifts and ionic behaviour. Core points Check your learning At equilibrium forward and reverse rates are equal. Write Kc and Kp for a reaction. K changes with temperature, not with catalyst or Calculate pH or solubility product in a initial concentration. simple system. Buffers resist pH change through a conjugate acid- base pair. Equation and notation K_p = K_c(RT)^Δn pH = −log[H⁺] K_w = [H⁺][OH⁻] SYMBOLS AND UNITS K_c: concentration equilibrium constant K_p: pressure equilibrium constant R: gas constant T: absolute temperature (K) Δn: gaseous-product moles minus gaseous-reactant [H+], [OH-]: molar concentrations (mol L⁻¹) moles pH: dimensionless One-line recall At equilibrium forward and reverse rates are equal. PADIKAM | CBSE NCERT CLASS 11 8

CHAPTER 07 Redox Reactions Quick understanding Track electron transfer through oxidation number and balance redox equations systematically. Core points Check your learning Oxidation raises oxidation number; reduction lowers Assign oxidation numbers in a it. polyatomic ion. Oxidising agent is reduced; reducing agent is Balance a redox equation in acidic or oxidised. basic medium. Charge and atoms must both balance. One-line recall Oxidation raises oxidation number; reduction lowers it. PADIKAM | CBSE NCERT CLASS 11 9

CHAPTER 08 Organic Chemistry: Some Basic Principles and Techniques Quick understanding Build a language for carbon compounds using structure, naming, electronic effects and purification. Core points Check your learning Identify the longest chain and principal functional Give IUPAC names and structural group before naming. isomers. Inductive, resonance and hyperconjugative effects Compare stability of reaction influence stability and reactivity. intermediates. Reaction intermediates include carbocations, carbanions and free radicals. Watch this Do not choose numbering before identifying the principal functional group. One-line recall Identify the longest chain and principal functional group before naming. PADIKAM | CBSE NCERT CLASS 11 10

CHAPTER 09 Hydrocarbons Quick understanding Compare alkanes, alkenes, alkynes and aromatic compounds through preparation, structure and reactions. Core points Check your learning Alkanes mainly undergo substitution and Predict products of addition to an combustion. unsymmetrical alkene. Unsaturated hydrocarbons undergo addition; Explain aromatic substitution in benzene. orientation may follow Markovnikov’s rule. Benzene favours electrophilic substitution because aromaticity is stabilising. Equation and notation Alkanes: CₙH₂ₙ₊₂ Alkenes: CₙH₂ₙ Alkynes: CₙH₂ₙ₋₂ SYMBOLS AND UNITS n: number of carbon atoms; n is a positive integer Subscripts: number of atoms of each element in one molecule One-line recall Alkanes mainly undergo substitution and combustion. PADIKAM | CBSE NCERT CLASS 11 11

CHAPTER 10 Formative Reading: The Gaseous State Quick understanding Extend gas behaviour through ideal assumptions, gas laws and molecular interpretation. Core points Check your learning Use kelvin temperature in every gas-law calculation. Solve a combined gas-law problem. The ideal-gas equation combines pressure, volume, Explain one cause of deviation from ideal amount and temperature. behaviour. Real gases approach ideal behaviour most closely at low pressure and high temperature. Equation and notation PV = nRT P₁V₁/T₁ = P₂V₂/T₂ SYMBOLS AND UNITS P: pressure (Pa) V: volume (m³) n: amount of gas (mol) R: gas constant (J mol⁻¹ K⁻¹) T: absolute temperature (K) One-line recall Use kelvin temperature in every gas-law calculation. PADIKAM | CBSE NCERT CLASS 11 12

CHAPTER 11 Formative Reading: s- and p-Block Elements Quick understanding Relate valence-shell configuration to characteristic properties and trends of representative elements. Core points Check your learning s-block elements have differentiating electrons in an Compare two group trends with reasons. s subshell; p-block elements in a p subshell. Explain anomalous behaviour of the first Group trends reflect changing size, ionisation element of a group. enthalpy and oxidation-state stability. Important compounds should be understood through preparation, structure, properties and use rather than isolated equations. Watch this This enrichment lesson is formative reading; follow the current school assessment notice for summative scope. One-line recall s-block elements have differentiating electrons in an s subshell; p-block elements in a p subshell. PADIKAM | CBSE NCERT CLASS 11 13