1. Ionic Compounds with Polyatomic Ions
Chemistry Part 8
Ionic Compounds with Polyatomic Ions

2. Polyatomic Ions An ion made up of 2 or more different atoms.
Covalent (non-ionic) bonds are between the atoms.
The charge belongs to the entire ion.
Names end in “ate” or “ite”.
See the back of your periodic table.

3. Polyatomic Ions Examples: Ammonium (only one with a positive charge)
NH41+
The charge is for the entire compound.
Phosphate
PO43-
Phosphite
PO33-

4. Formula Writing
Same process as before, but the polyatomic ion must be placed in brackets if it requires a subscript (more than one).

5. Formula Writing Example: Magnesium nitrate Mg  2+ NO3  1- Mg(NO3)2

6. Formula Writing
Example:
Iron (II) sulfate
Fe  2+
SO4  2-
FeSO4

7. Formula Writing
Example:
Ammonium sulfide
NH41+ and S2-
(NH4)2S

8. Formula Writing
Example:
Iron (II) nitrate
Pb2+ and NO31-
Pb(NO3)2

9. Nomenclature
Write the name of the metal (cation) If it is a transition metal, follow those rules.
Write the name of the polyatomic ion.

10. Nomenclature
Example:
NaNo3
Sodium nitrate
Ca(OH)2
Calcium hydroxide

11. Nomenclature Example: Fe(OH)3 1- Iron must have a 3+ charge
Iron (III) hydroxide 1- 1- 1-

12. Nomenclature Example: CuSO4 2- Copper must have a 2+ charge
Copper (II) sulfate 2-

13. Nomenclature
Example:
(NH4)2SO4
Ammonium sulfate

14. Practice
Worksheet
Page 127 # 17, 18