1. Aim: What properties do Ionic Compounds have?
Do Now:
What types of ions are in involved in ionic compounds?
What types of elements are usually involved in forming ionic bonds?
Explain, in terms of electrons, how ionic bonds are formed.

2. Ionic Bonding Process

4. Individual Practice
Show the electron transfer between atoms of potassium and nitrogen. Determine how many atoms of each element are required.
Draw the dot structure for the compound formed above.
*3. What would be the chemical formula for the above compound?

5. Properties of Ionic Compounds
Ionic substances form giant ionic crystals containing
oppositely charged ions.
High melting and boiling points - Ionic bonds are very strong - a lot of energy is needed to break them. So ionic compounds have high melting and boiling points
Ionic Compounds are neutral
Adding the charges of all the number of ions should equal zero

6. Properties continued
Conductive when liquid - Ionic compounds can only conduct electricity if their ions are free to move. Ionic compounds do not conduct electricity when they are solid - only when dissolved in water or melted.
A compound that conducts electricity is called an electrolyte.

7. Writing a chemical formula
A chemical formula tells us the number of atoms of each element in a compound. It contains the symbols of the atoms of the elements present in the compound, as well as how many there are for each element in the form of subscripts.

8. Example: Aluminum Chloride
Predicting Chemical Formula of Ionic Compounds
Criss-Cross Rule
Example: Aluminum Chloride
Step 1:
write out name with space
Al Cl 3+ 1-
Step 2:
write symbols & charge of elements
Al Cl
Step 3: 1 3
criss-cross charges as subscripts
Step 4: AlCl 3
combine as formula unit
(“1” is never shown)

9. Example: Aluminum Chloride
Criss-Cross Rule
Example: Aluminum Chloride
Step 1: Aluminum Chloride
Step 2: Al Cl1-
Step 3: Al Cl 1 3
Step 4: AlCl 3

10. Example: Aluminum Oxide
Criss-Cross Rule
Example: Aluminum Oxide
Step 1: Aluminum Oxide
Step 2: Al O2-
Step 3: Al O 2 3
Step 4: Al2O3

11. Example: Magnesium Oxide
Criss-Cross Rule
Example: Magnesium Oxide
Step 1: Magnesium Oxide
Step 2: Mg O2-
Step 3: Mg O 2 2
Step 4: Mg2O2
Step 5: MgO

12. Practice Using Criss-Cross Method to Predict Ionic Formulas
Predict the formulas of the ionic compounds formed form the following elements.
Potassium and oxygen
Magnesium and nitrogen
K O-2
K2O
Mg+2 N-3
Mg3N2

14. Practice: Write the chemical formulas for the compound formed between the following atoms
Barium and fluorine
Barium and oxygen
Aluminum and phosphorus
Lead (II) and sulfur
Lead (II) and chlorine
**Roman Numeral indicates charge for transition metal**