Memorizing Polyatomic Ions

Importance of Polyatomic Ions

• Essential for Chemistry courses.
• Necessary for writing formulas and balancing equations.
• Early knowledge aids future understanding.

Key Polyatomic Ions

Nitrogen-based Ions

1. NO3⁻ - Nitrate
2. NO2⁻ - Nitrite
3. N³⁻ - Nitride (Monoatomic ion)
   • Note: "ate" has one more oxygen than "ite".

Sulfur-based Ions

1. SO4²⁻ - Sulfate
2. SO3²⁻ - Sulfite
3. S²⁻ - Sulfide (Monoatomic ion)
   • Note: Suffix "ide" typically indicates lack of oxygen.

Phosphorus-based Ions

1. PO4³⁻ - Phosphate
2. P³⁻ - Phosphide (Monoatomic ion)
3. P3²⁻ - Phosphite
   • Match "ate" and "ite" rules.

Chlorine-based Ions

1. Cl⁻ - Chloride
2. ClO3⁻ - Chlorate
3. ClO2⁻ - Chlorite
4. ClO4⁻ - Perchlorate
5. ClO⁻ - Hypochlorite
   • Note: Prefix "per" indicates one more oxygen than "ate"; prefix "hypo" indicates one less.

Bromine-based Ions

1. Br⁻ - Bromide
2. BrO2⁻ - Bromite
3. BrO3⁻ - Bromate
4. BrO4⁻ - Perbromate

Iodine-based Ions

1. I⁻ - Iodide
2. IO2⁻ - Iodite
3. IO3⁻ - Iodate
4. IO4⁻ - Periodate

Other Important Ions

1. CO3²⁻ - Carbonate
2. HCO3⁻ - Hydrogen Carbonate (Bicarbonate)
3. C2H3O2⁻ - Acetate
4. C2O4²⁻ - Oxalate
5. CrO4²⁻ - Chromate
6. Cr2O7²⁻ - Dichromate
7. MnO4⁻ - Permanganate
8. OH⁻ - Hydroxide
9. NH4⁺ - Ammonium
   • Note: NH3 is ammonia, not an ion.

Naming Patterns

• Ate = More oxygen
• Ite = Less oxygen
• Ide = Monoatomic ions, typically lack oxygen
• Hydrogen prefix = Addition of H⁺ increases the charge by +1
  • Ex: HSO4⁻ = Hydrogen Sulfate

Review and Practice

• Quiz yourself on naming and identifying the formulas of various polyatomic ions.
• Examples: Write down formulas for ions such as sulfate, sulfite, nitride, etc.
• Important formulas to remember:
  • Sulfate -> SO4²⁻
  • Sulfite -> SO3²⁻
  • Hydrogen Sulfate -> HSO4⁻
  • Phosphate -> PO4³⁻
  • Hydronium -> H3O⁺

Common Mistakes

• Don't confuse polyatomic ions with their monoatomic counterparts (e.g., NH4⁺ vs. NH3).
• Be cautious with prefixes and suffixes to avoid naming errors.