Unit- 12. Basic Concept of Organic Chemistry : 6 teaching hours

Unit 12: Basic Concept of Organic Chemistry (6 Teaching Hours)

1. Introduction to Organic Chemistry and Organic Compounds

   • Definition
     • Organic chemistry: Study of carbon-containing compounds, primarily hydrocarbons and their derivatives.
     • Organic compounds: Contain C–C or C–H bonds; examples include methane (CH₄), ethanol (C₂H₅OH).

2. Reasons for the Separate Study of Organic Compounds from Inorganic Compounds

   • Reasons
     • Large number of organic compounds due to carbon’s unique bonding properties.
     • Complex structures, isomerism, and diverse reactions compared to inorganic compounds.
     • Covalent bonding in organic compounds vs. ionic in many inorganic compounds.
     • Slower reaction rates and specific reaction mechanisms in organic chemistry.

3. Tetra-covalency and Catenation Properties of Carbon

   • Tetra-covalency
     • Carbon has four valence electrons, forms four covalent bonds (e.g., CH₄ with four C–H bonds).
   • Catenation
     • Carbon’s ability to form long chains or rings by bonding with other carbon atoms (e.g., hydrocarbons like C₆H₁₄).
     • Figure 1: Tetra-covalency and Catenation of Carbon (Diagram showing CH₄ structure and carbon chain in hexane).

4. Classification of Organic Compounds

   • Classification
     • Hydrocarbons: Alkanes (e.g., CH₄), alkenes (e.g., C₂H₄), alkynes (e.g., C₂H₂), aromatic (e.g., C₆H₆).
     • Non-hydrocarbons: Alcohols (e.g., C₂H₅OH), aldehydes (e.g., CH₃CHO), carboxylic acids (e.g., CH₃COOH).
     • Open chain (aliphatic) vs. cyclic compounds (e.g., cyclohexane).
     • Figure 2: Classification of Organic Compounds (Diagram showing flowchart of organic compound types).

5. Alkyl Groups, Functional Groups, and Homologous Series

   • Alkyl Groups
     • Hydrocarbon groups derived by removing one H from alkanes (e.g., methyl: CH₃–, ethyl: C₂H₅–).
   • Functional Groups
     • Atoms or groups responsible for characteristic properties (e.g., –OH in alcohols, –COOH in carboxylic acids).
   • Homologous Series
     • Series of compounds with same functional group, differing by –CH₂– unit (e.g., CH₄, C₂H₆, C₃H₈).
     • Figure 3: Functional Groups and Homologous Series (Diagram showing examples of alkyl groups and homologous series).

6. Idea of Structural Formula, Contracted Formula, and Bond Line Structural Formula

   • Structural Formula
     • Shows arrangement of atoms and bonds (e.g., ethanol: CH₃–CH₂–OH).
   • Contracted Formula
     • Simplified representation grouping atoms (e.g., ethanol: C₂H₅OH).
   • Bond Line Structural Formula
     • Uses lines for bonds, vertices for carbon atoms (e.g., ethanol: zigzag line with –OH at end).
     • Figure 4: Types of Organic Formulas (Diagram showing structural, contracted, and bond line formulas of ethanol).

7. Preliminary Idea of Cracking and Reforming, Quality of Gasoline, Octane Number, Cetane Number, and Gasoline Additive

   • Cracking
     • Breaking large hydrocarbons into smaller, useful molecules (e.g., thermal cracking: C₁₀H₂₂ → C₅H₁₂ + C₅H₁₀).
   • Reforming
     • Rearranging hydrocarbons to improve quality (e.g., converting straight-chain alkanes to branched or aromatic compounds).
   • Quality of Gasoline
     • Determined by anti-knocking properties, measured by octane number.
   • Octane Number
     • Measures gasoline’s resistance to knocking; iso-octane = 100, n-heptane = 0.
   • Cetane Number
     • Measures diesel fuel’s ignition quality; cetane = 100, low cetane = poor ignition.
   • Gasoline Additive
     • Enhances fuel performance (e.g., tetraethyl lead (banned), MTBE for anti-knocking).
     • Figure 5: Cracking and Reforming Processes (Diagram showing cracking and reforming setups).