,  l Must-Know Polyatomic Ions for Gen Chem
1. Positive ion (cation):
• Ammonium – NH₄⁺
.
2. Negative ions (anions):
Oxyanions (with oxygen):
• Nitrate – NO₃⁻
• Nitrite – NO₂⁻
• Sulfate – SO₄²⁻
• Sulfite – S O₃²⁻
• Phosphate – PO₄³⁻
• Hydrogen phosphate – HPO₄²⁻
• Dihydrogen phosphate – H₂PO₄⁻
• Carbonate – CO₃²⁻
• Bicarbonate (hydrogen carbonate) – HCO₃⁻
• Hydroxide – OH⁻
• Chromate – CrO₄²⁻
• Dichromate – Cr₂O₇²⁻
• Permanganate – MnO₄⁻
Halogen-based oxyanions (pattern is important):
• Hypochlorite – ClO⁻
• Chlorite – ClO₂⁻
• Chlorate – ClO₃⁻
• Perchlorate – ClO₄⁻
(⚡ The same pattern applies to BrO⁻/IO⁻ if needed: hypo-, -ite, -ate, per-…ate)
1. Positive ion (cation):
• Ammonium – NH₄⁺
.
2. Negative ions (anions):
Oxyanions (with oxygen):
• Nitrate – NO₃⁻
• Nitrite – NO₂⁻
• Sulfate – SO₄²⁻
• Sulfite – S O₃²⁻
• Phosphate – PO₄³⁻
• Hydrogen phosphate – HPO₄²⁻
• Dihydrogen phosphate – H₂PO₄⁻
• Carbonate – CO₃²⁻
• Bicarbonate (hydrogen carbonate) – HCO₃⁻
• Hydroxide – OH⁻
• Chromate – CrO₄²⁻
• Dichromate – Cr₂O₇²⁻
• Permanganate – MnO₄⁻
Halogen-based oxyanions (pattern is important):
• Hypochlorite – ClO⁻
• Chlorite – ClO₂⁻
• Chlorate – ClO₃⁻
• Perchlorate – ClO₄⁻
(⚡ The same pattern applies to BrO⁻/IO⁻ if needed: hypo-, -ite, -ate, per-…ate)
