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.