1. Polyatomic Ionic Formulas

2. Polyatomic Ions + N H H H H What does NH4+ mean?
Ion contains: 1 Nitrogen H H N
Ion contains: 4 Hydrogens H H
Overall Charge: +1

3. Symbols for Polyatomic Ions
This charge applies to the ENTIRE ION
Symbol:
Ion Charge
NH4 +

4. Writing Formulas – Equal Charges
If the charge on the cation and anion are ________, drop the charges and put the two ions together
equal
Example) Al3+ PO  AlPO4

5. Polyatomic Ions – Unequal Charges
Let’s just look at an example with a polyatomic ion.
Write the ionic formula for:
Barium Nitrate
What’s the problem?
How could we fix it?

6. Writing Ionic Formulas-Polyatomic Ions
STEP
EXAMPLE
1) Write the cation first, then the anion.
Barium Nitrate Ba2+ NO3-
Same as before

7. Writing Ionic Formulas – Polyatomic Ions
STEP
EXAMPLE
2) Put parenthesis ( ) around the polyatomic ion or ions. Leave the charge on the outside!
Barium Nitrate Ba2+ (NO3)-
New Step!!

8. Writing Ionic Formulas – Polyatomic Ions
STEP
EXAMPLE
3) Drop the + and – (but NOT the numbers!!)
Barium Nitrate Ba2 (NO3)1
Same as before

9. Writing Ionic Formulas – Polyatomic Ions
STEP
EXAMPLE
4) Cross the charges. Leave the crossed charges on the outside!!
Barium Nitrate Ba2 (NO3)1
Ba1(NO3)2
Same as before – with a twist!!

10. Writing Ionic Formulas – Polyatomic Ions
STEP
EXAMPLE
5) Drop any “1”. ALSO: If you drop a “1” for a polyatomic ion, you may also drop parenthesis ( )
Barium Nitrate Ba1(NO3)2
Ba(NO3)2
Same as before – with a twist!!

11. Another Look Ba(NO3)2 1 Ba 2 SETS of NO3 1 Ba 2 N 6 O
What does this mean?
Ba(NO3)2
1 Ba 2 SETS of NO3
1 Ba 2 N
6 O

12. Writing Ionic Formulas-Polyatomic Ions
STEP
EXAMPLE
1) Write the cation first, then the anion.
Ammonium Phosphate NH4+ PO43-
Same as before

13. Writing Ionic Formulas – Polyatomic Ions
STEP
EXAMPLE
2) Put parenthesis ( ) around the polyatomic ion or ions. Leave the charge on the outside!
Ammonium Phosphate (NH4)+ (PO4)3-
New Step!!

14. Writing Ionic Formulas – Polyatomic Ions
STEP
EXAMPLE
3) Drop the + and – (but NOT the numbers!!)
Ammonium Phosphate (NH4)1 (PO4)3
Same as before

15. Writing Ionic Formulas – Polyatomic Ions
STEP
EXAMPLE
4) Cross the charges. Leave the crossed charges on the outside!!
Ammonium Phosphate (NH4)1 (PO4)3
(NH4)3(PO4)1
Same as before – with a twist!!

16. Writing Ionic Formulas – Polyatomic Ions
STEP
EXAMPLE
5) Drop any “1”. ALSO: If you drop a “1” for a polyatomic ion, you may also drop parenthesis ( )
Ammonium Phosphate (NH4)3(PO4)1
(NH4)3PO4
Same as before – with a twist!!

17. Writing Ionic Formulas – Polyatomic Ions
EXAMPLE
Magnesium Hydroxide
Mg2+ OH-
Mg2+ (OH)-
Mg2 (OH)1
Mg1(OH)2
Mg(OH)2

18. Writing Ionic Formulas – Polyatomic Ions
EXAMPLE
Lead (IV) Carbonate
Pb4+ CO32-
Pb4+ (CO3)2-
Pb4 (CO3)2
Pb2(CO3)4
Pb(CO3)2

19. Writing Ionic Formulas – Polyatomic Ions
EXAMPLE
Silver Chlorate
Ag+ ClO3-
Notice: The cation charge is +1 and the anion is -1
AgClO3

20. (NH4)2O NH4+ O2- Ammonium Oxide
Names – Example 1
(NH4)2O NH4+ O2- Ammonium Oxide

21. BaCrO4 Ba2+ CrO42- Barium Chromate
Names – Example 2
BaCrO4 Ba2+ CrO42- Barium Chromate

22. Fe2(C2O4)3 Fe3+ C2O42- Iron (III) Oxalate
Names – Example 3
Fe2(C2O4)3 Fe3+ C2O42- Iron (III) Oxalate

23. K3PO4 K+ (PO4)3- Potassium phosphate
Names – Example 4
K3PO4 K+ (PO4)3- Potassium phosphate

24. Group Practice
Ionic Formulas and Names – Polyatomic Ions – Group Practice

25. Group Practice - Check Station Cation Anion Ionic Formula Ionic Name 1
Aluminum
CO32- 2
NH4+
PO43- 3
Ba2+
Nitrate 4
Iron (III)
SO32- 5
Li+
BrO3- 6
Nitride

26. Group Practice - Check Station Cation Anion Ionic Formula Ionic Name 7
Cu2+
CO32- 8
Al3+
Phosphate 9
Pb2+
OH- 10
Pb4+
SO32-

27. Group Practice - Check Station Cation Anion Ionic Formula Ionic Name 1
Al3+
CO32-
Al2(CO3)3
Aluminum carbonate 2
NH4+
PO43-
(NH4)3PO4
Ammonium Phosphate 3
Ba2+
Nitrate
Ba(NO3)2
Barium Nitrate 4
Iron (III)
SO32-
Fe2(SO3)3
Iron (III) Sulfite 5
Li+
BrO3-
LiBrO3
Lithium Bromate 6
N3-
(NH4)3N
Ammonium nitrate

28. Group Practice - Check Station Cation Anion Ionic Formula Ionic Name 7
Cu2+
CO32-
CuCO3
Copper (II) Carbonate 8
Al3+
PO43-
AlPO4
Aluminum Phosphate 9
Pb2+
OH-
Pb(OH)2
Lead (II) Hydroxide 10
Pb4+
SO32-
Pb(SO3)2
Lead (IV) Sulfite

29. Group Practice - Check (NH4)3N Ammonium Nitrate FeSO3 Iron(II) Sulfite
Fe2(SO3)3 Iron(III) Sulfite
KNO3 Potassium Nitrate
Cd3(BO3)2 Cadmium Borate

30. Independent Practice
Ionic Formulas and Names – Polyatomic Ions – Individual Practice
Let me know if you have any questions!!!