Answer
🧪 Lewis Structure of 2-Aminopropionic Acid (Alanine)
1. Molecular Formula and Overview
- Molecular formula: C₃H₇NO₂
- Common name: Alanine
- Structure: CH₃–CH(NH₂)–COOH
- Alanine includes an amino group, a carboxylic acid group, and a central carbon bonded to a methyl group and hydrogen.
2. Valence Electron Calculation (Electron Budget)
| Atom | Quantity | Valence Electrons | Total Contribution |
|---|---|---|---|
| Carbon (C) | 3 | 4 | 12 |
| Hydrogen (H) | 7 | 1 | 7 |
| Nitrogen (N) | 1 | 5 | 5 |
| Oxygen (O) | 2 | 6 | 12 |
| Total Valence Electrons | 36 | ||
3. Skeleton Structure
Alanine’s backbone includes:
- Alpha carbon bonded to –CH₃, –H, –NH₂, and –COOH
H H
\\ /
H₃C – C – C = O
| \\
NHâ‚‚ OH
\\ /
H₃C – C – C = O
| \\
NHâ‚‚ OH
4. Octet Rule and Bonding
- Each carbon forms 4 covalent bonds
- Hydrogen atoms form 1 bond
- Nitrogen forms 3 bonds and 1 lone pair
- Oxygens in the carboxylic acid: one double bonded to C, the other single bonded to both C and H (OH group)
5. Final Lewis Structure Summary
The correct Lewis structure ensures that all atoms follow the octet rule (except H). It represents:
- 36 total valence electrons
- Functional groups: amino (–NH₂), carboxyl (–COOH)
- Molecular geometry needed for interactions such as hydrogen bonding and peptide bond formation
✅ Final Notes
The Lewis structure of alanine reflects the correct bonding arrangement and valence electrons for a biologically relevant amino acid. This foundational understanding is critical for analyzing acid-base behavior, zwitterion formation, and peptide synthesis.