Overview
This lecture covers the names, formulas, and charges of common polyatomic ions essential for honors-level chemistry.
Common Polyatomic Ions and Their Formulas
- Acetate: C₂H₃O₂⁻ or CH₃COO⁻
- Ammonium: NH₄⁺
- Carbonate: CO₃²⁻
- Bicarbonate (Hydrogen carbonate): HCO₃⁻
- Chlorate: ClO₃⁻
- Chlorite: ClO₂⁻
- Chromate: CrO₄²⁻
- Dichromate: Cr₂O₇²⁻
- Cyanide: CN⁻
- Hydroxide: OH⁻
- Nitrate: NO₃⁻
- Nitrite: NO₂⁻
- Permanganate: MnO₄⁻
- Phosphate: PO₄³⁻
- Hydrogen phosphate: HPO₄²⁻
- Dihydrogen phosphate: H₂PO₄⁻
- Sulfate: SO₄²⁻
- Sulfite: SO₃²⁻
- Hydrogen sulfate (bisulfate): HSO₄⁻
- Hydrogen sulfite (bisulfite): HSO₃⁻
Charges of Key Polyatomic Ions
- Most ions listed carry charges of -1, -2, or -3.
- Ammonium is a unique positive polyatomic ion (NH₄⁺).
- Phosphate family has -1 to -3 charges depending on hydrogen content.
Key Terms & Definitions
- Polyatomic Ion — A charged particle composed of two or more atoms covalently bonded.
- Acetate — C₂H₃O₂⁻; a common anion found in vinegar.
- Ammonium — NH₄⁺; the only common polyatomic cation.
- Carbonate — CO₃²⁻; an important ion in geology and biology.
- Chlorate — ClO₃⁻; an oxidizing agent.
- Dichromate — Cr₂O₇²⁻; used in cleaning and as an oxidizing agent.
Action Items / Next Steps
- Memorize each polyatomic ion's name, formula, and charge.
- Practice writing and recognizing these ions in chemical formulas.
- Prepare for quizzes or exams covering polyatomic ions.