1. Ch. 15 and 6 Polyatomic Ions

2. Polyatomic Ions
Tightly bound groups of atoms that behave as a unit and carry a charge.
Examples:
Ammonium
NH4+
Cyanide
CN-
Sulfite
SO32-

3. Common Polyatomic Ions with a -1 charge
ClO-1 hypochlorite
ClO2-1 chlorite
ClO3-1 chlorate
ClO4-1 perchlorate
CN-1 cyanide
MnO4-1 permanganate
NO3-1 nitrate
NO2-1 nitrite

4. -1 polyatomic ions cont. OH-1 hydroxide HCOO-1 formate
HCO3-1 hydrogen carbonate
HSO3-1 hydrogen sulfite
HSO4-1 hydrogen sulfate
CH3COO-1 or C2H3O2-1 acetate

5. -2 polyatomic ions C2O4-2 oxalate CO3-2 carbonate Cr2O7-2 dichromate
CrO4-2 chromate
SO4-2 sulfate
SO3-2 sulfite

6. -3 polyatomic ion
PO4-3 phosphate
PO3-3 phosphite

7. +1 polyatomic ions
NH4+1 ammonium
H3O+1 hydronium

8. Polyatomic Ions SO42- Sulfate Examine Relationships
Most end in –ite / -ate
Trick to remember:
The bigger number ate the little number!
SO42-
Sulfate
SO32-
Sulfite

9. The big number ate the little number!
NO3-
Nitrate
NO2-
Nitrite
PO43-
Phosphate
PO33-
Phosphite

10. Writing Formulas for Ternary Ionic Compounds
A. Contain a polyatomic ion
B. Same rules as for binary ionic compounds.
One addition – Use parenthesis if there is more than one polyatomic ion
Examples:
Calcium Hydroxide
Calcium - Ca2+ OH- –Hydroxide
Formula for compound – Ca(OH)2

11. Magnesium Dichromate Mg+2 Cr2O7-2 Mg2(Cr2O7)2 MgCr2O7 Boron acetate
B3+ C2H3O2-1
B(C2H3O2)3
Magnesium Dichromate
Mg+2 Cr2O7-2
Mg2(Cr2O7)2
MgCr2O7 11

12. Examples (cont.)
Magnesium Nitrate
Magnesium – Mg2+
Nitrate - ????
Write the formula for the compound

13. Practice Problems
Write formulas for the following ternary ionic compounds:
Calcium Carbonate
Potassium Sulfate
Barium Nitrite
Magnesium Phosphate
CaCO3
K2SO4
Ba(NO2)2
Mg3 (PO4)2

14. Naming Ternary Ionic Compounds
Same rules as for naming binary ionic compounds:
Name the cation – Use a Roman numeral if necessary
Name the anion
Do not use the word “ion” in the compound name

15. Practice Problems: Name the following ternary ionic compounds: NaCN
KClO
Li2SO3
CaC2O4
Al(OH)3
Sn3(PO4)2
Sodium cyanide
Potassium hypochlorite
Lithium sulfite
Calcium oxalate
Aluminum hydroxide
Tin (II) phosphate

16. Ionic Compounds- Polyatomic Ions Due at the end of class, CompletedOH
SO4
PO4
NO3
Zn+2
NH4 K Ca
Fe+3 -1 -1 -2 -3 -1 + + +2