chem lesson 5

• Polyatomic ions


  Groups of atoms that tend to stay together and carry an overall ionic charge
• Polyatomic ions


  • Nitrate ion (NO3-)
  • Sulfate ion (SO4 2-)
• Polyatomic compound


  A compound that contains a polyatomic ion
• Name of Polyatomic Ion

  • Nitrate (NO3-)
  • Sulfate (SO4 2-)
  • Phosphate (PO4 3-)
  • Carbonate (CO3 2-)
  • Chlorate (ClO3 -)
  • Hydroxide (OH-)
  • Ammonium (NH4 +)
  • Cyanide (CN-)
  • Nitrite (NO2 -)
  • Sulfite (SO3 2-)
  • Hydrogen carbonate (bicarbonate) (HCO3 -)
• Polyatomic Compounds


  • Calcium carbonate (CaCO3)
  • Magnesium hydroxide (Mg(OH)2)
  • Sulfuric acid (H2SO4)
  • Copper (II) sulfate (CuSO4)
• Writing Formulas for Polyatomic Compounds

  1. Write the symbols of the metal and of the polyatomic ion

  2. Write the ionic charges above the symbols and crisscross them

  3. If there is more than one of the polyatomic ion, a bracket is needed
• Writing Formulas for Polyatomic Compounds

  • Sodium and sulfate ion (Na2SO4)
  • Magnesium phosphate (Mg3(PO4)2)
• Naming Polyatomic Compounds


  The name is simply a combination of the name of the metal and the name of the polyatomic ion. Don't forget the Roman numeral if the metal has more than one possible charge.
• Naming Polyatomic Compounds


  • Barium sulfate (BaSO4)
  • Aluminum carbonate (Al2(CO3)3)
  • Iron (II) hydroxide (Fe(OH)2)
  • Ammonium bicarbonate (NH4HCO3)
  • Mercury (II) nitrate (Hg(NO3)2)
  • Calcium phosphate (Ca3(PO4)2)
  • Copper (I) nitrate (CuNO3)