Polyatomic Ions and
Ionic Bonding
What we know……………
 Ionic Bonds form between a metal and a non-metal
 In an ionic bond, electrons are transferred from the
metal (cation) to the non-metal (anion)
Polyatomic Ions
 An ion made up of two or more elements
 Elements stay together and act as one unit in chemical
reactions
 Together, the elements still carry charge
 Ex) hydroxide = OH-
Common Polyatomic Ions
Writing Formulas with
Polyatomics
 Follow the same procedure as we learned last class,
with one small exception.
 If more than one Polyatomic Ion is needed to balance the
charges, you must use parentheses around the ion before
writing subscript
 Ex: Magnesium Hydroxide (Mg+2, OH-1)
 Incorrect Formula: MgOH2
 Correct Formula: Mg(OH)2
Formula Examples
 Sodium Phosphate: Na+ + PO43- = Na3PO4
 Magnesium Phosphate: Mg2+ +
PO43- = Mg3(PO4)2
Naming with Polyatomics
 Good News! You just use the name of the polyatomic
ion!
 Ex: CaCO3
 Ca = calcium, CO3 = carbonate
 Name = calcium carbonate
Writing Polyatomics in
Formulas
 Write the formulas for the following compounds:
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Strontium Nitrite
Calcium Hydroxide
Iron (III) Carbonate
Copper (II) Sulfate
Ammonium Sulfide
Ammonium Nitrate
Naming with Polyatomic Ions
 Write the names of the following polyatomic ions:
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Mg(OH)2
Na2SO4
Al2(SO4)3
Pb3(PO4)4
NH4NO3
Mixed Practice - Naming
 Write the names for the following compounds
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AgCl3
Fr3N
Fe3(PO4)2
CuCO3
NaCl
Sn(CO3)2
NH4OH
Mixed Practice - Formulas
 Write the formulas for the following compounds
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Magnesium Peroxide
Tin (IV) Chromate
Ammonium Phosphate
Copper (II) Permanganate
Mercury (I) Chloride
Ammonium Oxide
Strontium Phosphide
Aluminum Iodide