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Organic Chemistry: Some Basic Principles and Techniques

NCERT Class 11 Chemistry Chapter 8

Organic Chemistry basics for Class 11, JEE and NEET: IUPAC naming, isomerism, inductive and resonance effects, mechanisms, purification and analysis.

10 topics Updated 8 Nov 2026

For: Class 11, JEE and NEET, unless a topic says otherwise

In the syllabus: JEE Class 11 syllabus, NEET Class 11 syllabus

With your textbook

NCERT Chemistry Part II (Class 11), Chapter 8 “Organic Chemistry – Some Basic Principles and Techniques”, reprint 2026-27.

Open the official NCERT chapter (PDF, 4.5 MB, ncert.nic.in)

Checked on 19 Oct 2026.

Learn in this order

  1. General introduction to organic chemistry

    What it studies, catenation, the vital force theory, Wöhler’s synthesis of urea, Kolbe and Berthelot, with solved examples.

    Class 11 only NCERT Section 8.1 9 min read 4 solved examples 8 practice questions

  2. Tetravalence of carbon: shapes of organic compounds

    Sp, sp and sp shapes, s character, π bonds and restricted rotation, with NCERT problems solved.

    NCERT Section 8.2 10 min read 4 solved examples 8 practice questions

  3. Structural representations of organic compounds

    Complete, condensed and bond-line formulas, wedge-dash 3-D drawings and molecular models, with problems.

    NCERT Section 8.3 12 min read 4 solved examples 8 practice questions

  4. Classification of organic compounds

    Acyclic, alicyclic and aromatic compounds, functional groups and homologous series.

    NCERT Section 8.4 10 min read 4 solved examples 8 practice questions

  5. Nomenclature of organic compounds

    Naming rules for branched alkanes, functional group priority, rings and benzene derivatives, with examples.

    NCERT Section 8.5 16 min read 6 solved examples 10 practice questions

  6. Isomerism

    Chain, position and functional group isomers, metamers, geometrical and optical isomerism, with solved examples.

    NCERT Section 8.6 11 min read 5 solved examples 8 practice questions

  7. Fundamental concepts in organic reaction mechanism

    Bond fission, carbocations, nucleophiles, inductive and resonance effects, hyperconjugation.

    NCERT Section 8.7 23 min read 6 solved examples 9 practice questions

  8. Methods of purification of organic compounds

    Sublimation, crystallisation, simple, fractional and steam distillation, TLC and Rf values.

    NCERT Section 8.8 14 min read 4 solved examples 9 practice questions

  9. Qualitative analysis of organic compounds

    Tests for C, H, N, S, halogens and P, with solved examples.

    NCERT Section 8.9 12 min read 5 solved examples 8 practice questions

  10. Quantitative analysis of organic compounds

    Estimating C, H, N (Dumas, Kjeldahl), halogens, S, P and O, with NCERT problems.

    NCERT Section 8.10 17 min read 6 solved examples 9 practice questions

Key formulas in this chapter

General introduction to organic chemistry

  • Wöhler (1828): NHCNO → NHCONH on heating (both CHNO)
  • Kolbe (1845): acetic acid; Berthelot (1856): methane

Tetravalence of carbon and shapes

  • σ bonds around carbon: 4 → sp (109.5°), 3 → sp (120°), 2 → sp (180°)
  • s character: sp 50% > sp 33% > sp 25%
  • Single bond = 1 σ; double = 1 σ + 1 π; triple = 1 σ + 2 π

Structural representations

  • Hydrogens on a bond-line carbon = 4 − bonds drawn to it (double line = 2, triple line = 3)
  • Single bonds only: line end = CH; two lines = CH; three lines = CH; four lines = C

Classification of organic compounds

  • Alkanes: CnH2n+2; alkenes: CnH2n; alkynes: CnH2n−2
  • Successive homologues differ by CH = 14 u

IUPAC nomenclature of organic compounds

  • Name = prefixes with locants + root + -ane/-ene/-yne + suffix
  • ortho = 1,2; meta = 1,3; para = 1,4

Isomerism

  • Isomers: same molecular formula, different structure or arrangement in space
  • Alkane structural isomers: CH 2, CH 3, CH 5, CH 9 (11 with mirror-image forms)

Organic reaction mechanism

  • Carbocation stability: CH < CHCH < (CH)CH < (CH)C
  • Hyperconjugating C–H bonds: 0, 3, 6, 9
  • Inductive effect: −I (halogens, NO, CN, COOH); +I (alkyl groups)

Purification of organic compounds

  • Rf = distance moved by substance/distance moved by solvent (both from the base line)
  • Steam distillation: p = p1 + p2

Qualitative analysis of organic compounds

  • Na + C + N → NaCN; 2Na + S → NaS; Na + X → NaX
  • 3[Fe(CN)] + 4Fe → Fe[Fe(CN)] (Prussian blue)
  • S + Pb → PbS (black); X + Ag → AgX

Quantitative analysis

  • % C = 12 × m2 × 100/(44 × m); % H = 2 × m1 × 100/(18 × m)
  • Dumas: % N = 28 × V × 100/(22 400 × m), V at STP
  • Kjeldahl: % N = 1.4 × M × 2(V − V1/2)/m
  • % X = atomic mass of X × m1 × 100/(molar mass of AgX × m)
  • % S = 32 × m1 × 100/(233 × m)

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