Lecture Notes: Skeletal Structure and Lewis Diagrams

Goals of the Lecture

• Understand how to convert a loose diagram into a skeletal structure.
• Learn to reinsert invisible hydrogens into a skeletal structure to revert it back to a Lewis diagram.

Example: Ketone Conversion

• Step 1: Identify the longest carbon chain.
  • Example given: Longest carbon chain is 6 carbons.
  • Draw a line with 6 segments to represent the chain.
• Step 2: Add functional groups to the carbon chain.
  • First carbon: add an -OH group.
  • Second carbon: add a double-bonded oxygen.
  • Continue adding groups per carbon chain details.
• Step 3: Note tetrahedral geometry.
  • Skeletal structures ignore specific directions of hydrogens and some groups due to tetrahedral geometry.

Rules for Skeletal Structures

• Do not draw hydrogens attached to carbons.

Reinserting Invisible Hydrogens

• Concept: Carbons form 4 bonds; missing bonds imply hydrogen presence.
• Application: Check each carbon for missing bonds and assume additional hydrogens.

Lewis Diagram

• Depicts all bonds in a molecule, including hydrogens.
• For the example, the Lewis diagram shows hexagonal carbon arrangement with one hydrogen per carbon.
• Comparison: Skeletal diagrams are faster to draw but omit hydrogens for simplicity.

Advantages of Skeletal Structures

• More efficient for drawing complex molecules like benzene.

Next Class

• Introduction to naming conventions for organic molecules.