Lecture3

Lecture Overview

  • Date: January 09, 2025

  • Lecture Number: 3

  • Chapter: 4

  • Pages: 56-65

  • Edition: 11th

  • Instructor: Amancio José de Souza

Carbon: The Backbone of Life

  • Carbon is a fundamental element in organic compounds.

Organic Chemistry Basics

  • Definition: Study of carbon-containing compounds.

  • Historical Context:

    • Began in the 1800s

    • First synthetic organic compound: urea by Wöhler.

    • Originally thought organic compounds arose only from biological sources.

  • Presently, complex organic compounds can be synthesized artificially.

Diversity of Organic Molecules

  • Organic compounds vary from simple to extremely complex molecules.

  • Key Experiment: 1953 Stanley Miller Experiment mimicking early Earth conditions to synthesize biological molecules abiotically.

Carbon's Unique Properties

  • Bonding Capabilities: Carbon can bond with four other atoms due to its four valence electrons.

    • This property enables the formation of diverse, complex molecules.

Electron Configuration

  • Determines how many bonds an atom can form, influencing the molecule's overall structure.

Valence Electrons of Key Elements

  • Hydrogen: Valence = 1

  • Oxygen: Valence = 2

  • Nitrogen: Valence = 3

  • Carbon: Valence = 4

Molecular Structure Examples

  • Methane (CH4): Fundamental hydrocarbon.

  • Ethane (C2H6): Two carbon atoms.

  • Ethene (C2H4): Presence of a double bond.

Drawing Organic Compounds

  • Use of implicit hydrogens in molecular structures.

  • Different types of representations: Line-angle formulas, Lewis structures.

Hydrocarbons

  • Definition: Organic molecules made only of carbon and hydrogen.

  • Examples: Fats that contain hydrocarbon components.

  • Hydrocarbons can release significant energy during reactions.

Carbon Skeleton Diversity

  • Varieties include:

    • Length (e.g., Ethane, Propane)

    • Branching (e.g., Butane vs. Isobutane)

    • Double bond position (e.g., 1-Butene vs. 2-Butene)

    • Presence of rings (e.g., Cyclohexane, Benzene)

Isomers

  • Definition: Compounds with identical molecular formulas but different atom arrangements.

  • Types of Isomers:

    1. Structural Isomers

    2. Cis/Trans Isomers

    3. Enantiomers (mirror images, typically involving asymmetric carbon)

Functional Groups

  • Functional groups contribute to the molecule's characteristics, including:

    1. Hydroxyl (–OH): Found in alcohols, forms hydrogen bonds.

    2. Carbonyl (C=O): Has ketones (within molecule) and aldehydes (at molecule's end).

    3. Carboxyl (–COOH): Highly polar, acts as acid by donating hydrogen ion (H+).

    4. Amino (–NH2): Polar, accepts H+ in solutions, found in amino acids.

    5. Sulfhydryl (–SH): Found in cysteine, forms thiols.

    6. Phosphate (–PO4): Polar, present in nucleotides like ATP.

    7. Methyl (–CH3): Hydrophobic, significant role in DNA.

Summary of Key Concepts

  • Carbon: Has a valence of 4 enabling various compound formations.

  • Isomers: Structural, cis/trans, and enantiomers contribute to molecular diversity.

  • Functional Groups: Importance in recognizing molecule types and impacting carbon skeleton properties.

Upcoming Topics

  • Discussion on Macromolecules (Chapter 5) includes:

    • Carbohydrates

    • Lipids

    • Proteins

    • Nucleic acids

    • Understanding their properties and recognition.