1. (2.2) IONIC COMPOUNDS- POLYATOMIC
NAMES & FORMULAS…MORE

2. Polyatomic Ions A polyatomic ion:
is an ion that is made up of two or more atoms
has a positive or negative charge

3. Polyatomic Ions Example: nitrate ion NO31- This ion has a charge of -1

4. Polyatomic Ions We use polyatomic compounds in our daily life!
ex. ammonium nitrate NH4NO (fertilizer)
calcium carbonate CaCO (chalk)

5. Some Common Polyatomic Ions
Name of ion
Formula
Charge
ammonium
NH41 +1
hydroxide
OH1- -1
nitrate
NO31-
carbonate
CO32- -2
sulfate
SO42-

6. Writing Formulas
To write a formula for a polyatomic compound use the “criss-cross” method.
Examples:
a) sodium nitrate NaNO3
b) calcium hydroxide
c) ammonium nitrate
d) potassium carbonate
NOTE: (use brackets where needed)

7. Writing Formulas
To write a formula for a polyatomic compound use the “criss-cross” method.
Examples:
a) sodium nitrate NaNO3
b) calcium hydroxide Ca(OH)2
c) ammonium nitrate NH4NO3
d) potassium carbonate K2CO3
NOTE: (use brackets where needed)

8. Let’s review Some videos The Formation of Metal Ions
Writing a Chemical Formula based on a Name: Aluminum Oxide

9. PRACTICE Worksheet 2.2 (B) compound naming Did You Complete? Workbook
Quiz tomorrow Ionic Compounds