Structure 3.2.1
Types of Formulas
Organic compounds can be represented by different types of formulas: empirical, molecular, structural (full and condensed), stereochemical, and skeletal.
1. Hierarchy of Formulas
| Type | Definition | Example (Butanoic Acid) |
|---|---|---|
| Empirical | Simplest whole number ratio of atoms. | |
| Molecular | Actual number of atoms of each element. | |
| Structural (Full) | Shows every bond and every atom (Lewis structure style). | All lines drawn |
| Structural (Condensed) | Shows the arrangement without drawing bonds. | |
| Skeletal | Zig-zag lines. Carbon atoms at corners/ends. Hydrogens on carbons are hidden. | Zig-zag line ending in OH |
2. Skeletal Formulas: The Rules
What to Draw
- Lines represent bonds.
- Ends of lines and corners represent Carbon atoms.
- Heteroatoms (O, N, Cl, Br, etc.) MUST be drawn.
- Hydrogens attached to Heteroatoms (e.g., -OH, -NH) MUST be drawn.
What NOT to Draw
- Do not write 'C' for carbons in the chain (unless explicitly needed for clarity).
- Do not draw Hydrogens attached to Carbons. They are implied to satisfy carbon's valency of 4.