# Step-by-Step Solution: Completing the Lewis Structure of C₈H₈NO⁻ ## 1. **Given Information** - Formula: **C₈H₈NO⁻** - Skeleton provided (usually, this is a carbon framework with O and N attached, hydrogens not shown) - **Oxygen** must carry a **-1 formal charge** - Need to add: - All hydrogens - All π bonds (double/triple bonds) - All valence electrons (lone pairs and bonds) --- ## 2. **Count Valence Electrons** - C (carbon): 4 valence electrons × 8 = **32** - H (hydrogen): 1 valence electron × 8 = **8** - N (nitrogen): **5** - O (oxygen): **6** - Charge: **-1** (add 1 electron) - **Total:** 32 + 8 + 5 + 6 + 1 = **52 valence electrons** --- ## 3. **General Approach** - Draw all single bonds based on the skeleton (assumed aromatic ring, perhaps a benzene derivative). - Add π bonds typical for aromatic stabilization if a benzene ring is present. - Place hydrogens to complete carbon valences (4 bonds each). - Add lone pairs to O and N as needed to fulfill their octets and the formal charge requirement. --- ## 4. **Possible Skeleton** Without an image, a common C₈H₈NO⁻ anion from this formula is the **deprotonated form of 8-hydroxyquinoline** or a **substituted benzene** (like para-aminobenzoate). For this example, let's use the **para-aminobenzoate anion** (p-aminobenzoic acid, with carboxylate as the -1 site): ``` NH2 | | C6---C1----C2 | | C5 C3 | | C4---------C7--COO⁻ ``` Where: - Benzene ring is C1–C6 - NH₂ group at para to CO₂⁻ (on C1 and C4) - Carboxylate (COO⁻) at C7 --- ## 5. **Draw Bonds and Atoms** ### **Aromatic Ring** - Each C in benzene ring gets 1 H except where substituted (NH₂, COO⁻). - Alternate double bonds for aromaticity. ### **Substituents** - **NH₂** on C1: N attached to C, two hydrogens on N, N has a lone pair. - **COO⁻** on C7: C double bonded to one O (with two lone pairs), single bonded to the other O (with three lone pairs, carrying the -1 charge). --- ## 6. **Add Hydrogens** - **Benzene ring**: 4 H (since two positions have substituents). - **NH₂**: 2 H on N. - **COO⁻**: no H. --- ## 7. **Add π Bonds and Lone Pairs** - **Aromatic ring**: three double bonds. - **COO⁻**: one C=O double bond, one C–O⁻ single bond. - **Oxygens**: each O has enough lone pairs to complete octet. - **NH₂**: N has one lone pair. --- ## 8. **Formal Charges** - O with three lone pairs and one single bond (COO⁻): formal charge = -1 --- ## 9. **Final Structure** ### **Lewis Structure Overview** ```plaintext H H | | H–C6=C1–C2–H | | C5 C3 | | H–C4=C7–COO⁻ | NH2 ``` - **Aromatic ring**: alternate double bonds, hydrogens on non-substituted carbons. - **NH₂** on C1: N attached to two H, one lone pair. - **COO⁻** on C7: one O double bonded (two lone pairs), one O single bonded (three lone pairs, formal charge -1). --- ## 10. **Electron Count Check** - All atoms have complete octets (except H). - Total electrons: match calculated valence. --- ## 11. **Final Answer (Description)** - **C₈H₈NO⁻ anion** is best represented as the deprotonated form of para-aminobenzoic acid. - **Structure:** - Benzene ring with NH₂ at para position to COO⁻ group. - COO⁻ group: one O with three lone pairs and -1 charge, one O with two lone pairs (C=O). - All hydrogens, π bonds, and lone pairs properly placed. - **The -1 charge is located on the singly bonded oxygen of the carboxylate group.** --- ### **[See example structure below:]**  --- ## 12. **Summary Table** | Atom / Group | Bonds/Lone Pairs | Hydrogens | Charge | |---------------------|------------------|-----------|--------| | Aromatic Carbons | 3 bonds + 1 H | 4 total | | | NH₂ (on ring) | 2 N–H, 1 lone pair | 2 | | | COO⁻ (on ring) | 1 C=O, 1 C–O⁻, 2/3 lone pairs | | -1 (on O⁻) | --- ## **Final Answer** **The completed Lewis structure of C₈H₈NO⁻ (para-aminobenzoate anion) features:** - A benzene ring with alternating double bonds, - An NH₂ group at the para position, - A carboxylate group (COO⁻) with one oxygen carrying the -1 charge (three lone pairs), - All hydrogens, π bonds, and lone pairs explicitly drawn. **The -1 formal charge is located on the single-bonded oxygen of the carboxylate group.**