1. Ionic Compounds #4 Polyatomic Ions
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Publishing as Benjamin Cummings

2. Polyatomic Ions A polyatomic ion
Is a group of atoms that formed by sharing their electrons.
As a group or unit, they have an overall + or - charge
Some examples of polyatomic ions:
NH4+ ammonium OH− hydroxide
NO3− nitrate NO2− nitrite
CO32− carbonate PO43− phosphate
HCO3− hydrogen carbonate
( also called bicarbonate)

3. Some Compounds with Polyatomic Ions
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Publishing as Benjamin Cummings

4. You are getting a polyatomic ion sheet to use for the year!
Attach it to the BACK of your Periodic Table so that you always have it handy!!

5. More Names of Polyatomic Ions
The names of common polyatomic anions…
End in -ate.
NO3− nitrate PO43− phosphate
If they have one oxygen less end in -ite.
NO2− nitrite PO33− phosphite
With hydrogen attached use prefix hydrogen (or bi).
HCO3− hydrogen carbonate (bicarbonate)
HSO3− hydrogen sulfite (bisulfite)

6. Names and Formulas of Common Polyatomic Ions
Copyright © by Pearson Education, Inc.
Publishing as Benjamin Cummings

7. Names and Formulas of Common Polyatomic Ions
Copyright © by Pearson Education, Inc.
Publishing as Benjamin Cummings

8. Prefixes for Names of Polyatomic Ions of Halogens
Polyatomic ions containing halogens may require prefixes.
An example:
ClO4− perchlorate one oxygen more
ClO3− chlorate most common form
ClO2− chlorite one oxygen less
ClO− hypochlorite two oxygens less

9. Some Compounds with Polyatomic Ions
Table 5.7
Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings

10. Writing Formulas with Polyatomic Ions
The formula of an ionic compound
Containing a polyatomic ion must have a charge balance that equals zero(0).
Na+ and NO3− → NaNO3
If you need two or more polyatomic ions to balance the charges, you MUST enclose the polyatomic ions in parentheses.
Mg2+ and 2NO3− → Mg(NO3)2
subscript 2 to balance the charges

11. To write the formula from the name…
Identify the cation; refer to the periodic table to look up its charge OR if it’s got a Roman numeral, that IS its charge
--Watch out for ammonium NH4+ because it is a cation that is also polyatomic…you won’t find it on your periodic table!

12. To write the formula from the name…
Identify the anion; refer to the periodic table (especially if it ends in –ide) to look up its charge OR look it up on your polyatomic ion sheet.
Remember, most polyatomic ions are anions

13. To write the formula from the name…
3. Balance your charges…how many do you need of each ion?
Do you need more than one of a polyatomic ion? If so, put parentheses around it, with the appropriate subscript indicating how many are needed.
Be sure your cation/s is/are first and your anion/s is/are last.

14. Learning Check—TRY THESE!
Select the correct formula for each:
A. aluminum nitrate
1) AlNO ) Al(NO) ) Al(NO3)3
B. copper(II) nitrate
1) CuNO3 2) Cu(NO3)2 3) Cu2(NO3)
C. iron (III) hydroxide
1) FeOH 2) Fe3OH 3) Fe(OH)3
D. tin(IV) hydroxide
1) Sn(OH)4 2) Sn(OH) ) Sn4(OH)

15. Solution Select the correct formula for each: A. aluminum nitrate
3) Al(NO3)3
B. copper(II) nitrate
2) Cu(NO3)2
C. iron(III) hydroxide
3) Fe(OH)3
D. tin(IV) hydroxide
1) Sn(OH)4

16. Learning Check Write the correct formula for each:
A. potassium bromate
B. calcium carbonate
C. sodium phosphate
D. iron(III) oxide
E. iron (II) nitrite

17. Solution Write the correct formula for each:
A. potassium bromate KBrO3
B. calcium carbonate CaCO3
C. sodium phosphate Na3PO4
D. iron(III) oxide Fe2O3
E. iron (II) nitrite Fe(NO2)2

18. Naming Compounds with Polyatomic Ions
The positive ion (cation) is named first followed by the name of the polyatomic anion.
Transition metals (except Ag, Cd, and Zn), tin, and lead must still have a roman numeral to indicate which ion is in the compound…if you notice the cation is one of these metals, start with the ANION to help you to figure out the charge/roman numeral of the cation:
NaNO3 sodium nitrate
K2SO4 potassium sulfate
Fe(HCO3)3 iron(III) bicarbonate
or iron(III) hydrogen carbonate

19. Learning Check Match each formula with the correct name:
A. MgS 1) magnesium sulfite
MgSO3 2) magnesium sulfate
MgSO4 3) magnesium sulfide
B. Ca(ClO3)2 1) calcium chlorate
Ca(ClO)2 2) calcium chlorite
Ca(ClO2)2 3) calcium hypochlorite

20. Solution Match each formula with the correct name:
A. MgS 3) magnesium sulfide
MgSO3 1) magnesium sulfite
MgSO4 2) magnesium sulfate
B. Ca(ClO3)2 1) calcium chlorate
Ca(ClO)2 3) calcium hypochlorite
Ca(ClO2)2 2) calcium chlorite

21. Learning Check Name each of the following compounds: A. Mg(NO3)2
B. Cu(ClO3)2
C. PbO2
D. Fe2(SO4)3
E. Ba3(PO3)2

22. Solution Name each of the following compounds:
A. Mg(NO3)2 magnesium nitrate
B. Cu(ClO3)2 copper(II) chlorate
C. PbO2 lead (IV) oxide
D. Fe2(SO4)3 iron(III) sulfate
E. Ba3(PO3)2 barium phosphite

23. Naming Ionic Compounds--Summary
Table 5.8
Copyright © by Pearson Education, Inc. Publishing as Benjamin Cummings

24. Flowchart for Naming
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25. Learning Check Name the following compounds: A. Ca3(PO4)2 B. FeBr3
C. Al2S3
D. Mn(NO2)2
E. NaHCO3

26. Solution Name the following compounds:
A. Ca3(PO4) Ca2+ PO43− calcium phosphate
B. FeBr Fe3+ Br − iron(III) bromide
C. Al2S Al3+ S2− aluminum sulfide
D. Mn(NO2) Mn2+ NO2− manganese(II) nitrite
E. NaHCO Na+ HCO3− sodium hydrogen carbonate
sodium bicarbonate

27. Learning Check Write the formulas for the following:
A. calcium nitrate
B. iron(II) hydroxide
C. aluminum carbonate
D. copper(II) hypobromite
E. lithium phosphate

28. Solution Write the formulas for the following:
A. calcium nitrate Ca2+, NO3− Ca(NO3)2
B. iron(II) hydroxide Fe2+, OH− Fe(OH)2
C. aluminum carbonate Al3+, CO32− Al2(CO3) 3
D. copper(II) hypobromite Cu2+, BrO− Cu(BrO)2
E. lithium phosphate Li+, PO43− Li3PO4