Representing Formulas of Organic Compounds

Overview

• Organic compounds can be represented using different formula types:
  • Empirical
  • Molecular
  • Structural
  • Condensed Structural
  • Skeletal
  • Stereochemical

Types of Formulas

Empirical Formula

• Shows the simplest whole-number ratio of atoms in a compound.
• Example: Hydrogen peroxide (H2O2) -> empirical formula is HO.

Molecular Formula

• Displays the actual number of atoms in a molecule.
• Example: Butane (C4H10) and Butene (C4H8).

Worked Example

• Example compound: C2H4Cl2
  • Molecular formula: C2H4Cl2
  • Empirical formula: CH2Cl

Structural Formula

• Portrays the spatial arrangement of all atoms and bonds.
• Example: 2-methylbutane.

Condensed Structural Formula

• Displays enough info for clarity, omitting most covalent bonds.
• Example: Hexane - Full formula vs. Condensed formula.

Skeletal Formula

• Simplifies representation using straight lines for carbon bonds.
• Only shows functional groups and atoms other than carbon explicitly.

Worked Examples

Skeletal Formula Example

• Example molecules:
  1. CH3(CH2)3OH
  2. (CH3)2CHCH2OH
  3. CH3CH2OCH2CH3

Stereochemical Formula

• Illustrates 3D arrangement around chiral carbon, using:
  • Solid lines (in the plane)
  • Solid wedges (coming out of the plane)
  • Dashed wedges (going behind the plane)
• Chiral carbon has four different groups attached, forming a tetrahedral shape.

Diagram Example

• Demonstrates the use of lines and wedges to show spatial orientation.

Additional Notes

• Methane does not have a skeletal formula as it only has one carbon.
• Skeletal formulas rely on carbon-carbon bonds, important in distinguishing from structural formulas.

Author

• Richard Boole, Chemistry Content Creator, with over 15 years of teaching experience.
• Emphasizes helping students learn effective study techniques.