Lecture Notes: Drawing Lewis Dot Structures and Condensed Structures

Introduction

• Molecular Formula: C₃H₈O
• Objective: Draw and understand different representations of the molecular structure.

Lewis Dot Structure

• Example Provided:
  • 3 Carbon atoms
  • 1 Oxygen atom
  • 8 Hydrogen atoms
• Characteristics:
  • Shows all bonds explicitly.
  • Time-consuming to draw.

Condensed Structures

Partially Condensed Structure

• Focus on Central Carbon (Red):
  • Bonded to an OH group.
  • Bonded to a Hydrogen.
  • Bonded to another Carbon (Magenta) which is bonded to three Hydrogens (CH₃).
• Left Carbon (Blue):
  • Bonded to three Hydrogens (another CH₃).
• Representation:
  • Highlights connectivity without showing all bonds.
  • Contains same information as Lewis structure.

Fully Condensed Structure

• Central Carbon (Red):
  • Bonded to two CH₃ groups.
  • Bonded to a Hydrogen.
  • Bonded to an OH group.
• Representation Format:
  • e.g., (CH₃)₂CHOH
  • No bonds drawn, bonding inferred by structure.

Converting Between Structures

From Condensed to Lewis Structure

1. Start with Condensed Formula:
   • Example: CH₃₃COCH₃
2. Draw Partially Condensed Structure:
   • Central carbon bonded to three CH₃ groups and one Oxygen.
   • Oxygen bonded to another CH₃ group.
3. Expand to Full Lewis Structure:
   • Include all bonds and lone pairs.
   • Example depicted with CH₃ groups fully expanded.

Skills and Applications

• Conversion Flexibility:
  • Ability to convert between condensed, partially condensed, and full Lewis structures.
  • Useful for small molecules.
• Limitations for Large Molecules:
  • More complex organic molecules often use bond line structures.

Conclusion

• Understanding different structural representations aids in better comprehension of molecular geometry and connectivity.
• Future lessons will cover bond line structures for larger molecules.