Lecture Notes: Introduction to Organic Chemistry

Overview

• Transitioning from basic chemistry to organic chemistry.
• Focus on carbon-based compounds.

Importance of Carbon

• Carbon's valence of four allows it to form up to four covalent bonds.
• Essential for complex molecule formation such as proteins, DNA, carbohydrates, and lipids.

Definition and Scope of Organic Chemistry

• Study of carbon-containing compounds.
• Includes both small molecules and large macromolecules.
• Debate on whether hydrogen must be present alongside carbon for a compound to be considered organic.

Historical Perspective: Vitalism vs. Mechanism

• Vitalism: Early belief that life-force outside physical and chemical laws was necessary for life.
• Mechanism: Current view that physical/chemical laws govern all natural phenomena.

Key Historical Experiments

• German Chemist's Experiment: Accidental synthesis of urea in an abiotic system.
• Stanley Miller's Experiment: Simulated early Earth conditions, produced amino acids abiotically.
  • Used a set-up mimicking pre-life Earth with water, methane, ammonia, hydrogen, and electric sparks.
  • Demonstrated the possibility of organic molecule formation without life.

Carbon's Electron Configuration

• Carbon has 6 electrons: 2 in the first shell, 4 in the valence shell.
• Can share electrons to fulfill the octet rule, allowing complex molecules.

Shapes and Structures of Organic Molecules

• Tetrahedral Shape: Common in simple organic molecules like methane and ethane.
• Single vs. Double Bonds:
  • Single bonds allow rotation (e.g., ethane).
  • Double bonds prevent rotation, flattening the molecule (e.g., ethene).

Isomers

• Importance of molecular arrangement and the impact of double bonds on molecular structure.

Carbon's Binding Partners

• Prefers forming bonds with hydrogen, oxygen, and nitrogen.
• These elements make up 96% of living organisms.

Examples of Carbon-Based Molecules

• Carbon Dioxide (CO2): Carbon double bonded to oxygen, relevant for respiration and photosynthesis.
• Urea: Contains carbon and nitrogen, component of urine, showcases diverse bonding in organic molecules.

Conclusion

• Carbon's versatility in bonding allows for the diversity of organic compounds essential for life.