Organic Chemistry – Some Basic Principles and Techniques — Class 11 Chemistry

This foundational unit sets out the principles needed to study carbon compounds, beginning with the historical collapse of the vital-force theory after Wöhler synthesised urea in the laboratory. Carbon's tetravalence and its unique ability to catenate, explained through sp, sp and sp hybridisation, govern the tetrahedral, planar and linear shapes of organic molecules and the features of pi bonds. Structures are represented by complete, condensed and bond-line formulae, by three-dimensional wedge-and-dash notation and by molecular models. Organic compounds are classified as acyclic (aliphatic), alicyclic, aromatic and heterocyclic, and are grouped by functional group into homologous series whose successive members differ by a CH unit. The IUPAC system names a compound from its parent chain, principal functional group, substituent prefixes and lowest locants. Isomerism is divided into structural (chain, position, functional and metamerism) and stereoisomerism (geometrical and optical). The fundamentals of reaction mechanism cover the homolytic and heterolytic fission of covalent bonds, giving free radicals, carbocations and carbanions; the distinction between nucleophiles and electrophiles; the curved-arrow notation for electron movement; and the electron-displacement effects of induction, resonance, the electromeric effect and hyperconjugation. The unit also introduces the main types of organic reactions and the laboratory techniques of purification (crystallisation, distillation, chromatography) and qualitative and quantitative elemental analysis.