1. Sponge Give the ionic compound for the following: K+ + O2- Sr2+ + Cl-
Na+ + F-
Fe3+ + Cl-

2. Ionic Bonding Part 2
Chemistry
Unit 3, Day 2

3. Properties of Ionic Compounds
Crystal Lattice Structure
Each positive ion is surrounded by negatives
Each negative ion is surrounded by positives
Strong Bonds
Require large amounts of energy to break apart
High melting points
High boiling points
Hard, Rigid, Brittle solids

4. Strength of the Bond
Energy required to separate one mole of the ions of an ionic compound is referred to as Lattice Energy
The more negative the energy, the stronger the force of attraction, the harder to separate ions
Compound
Lattice Energy (kJ/mol)
KBr
-671
NaBr
-732
AgCl
-910
SrCl2
-2142

5. RECALL: Writing Formula Units
The formula unit (product) must be neutral (zero charge)
Add the ions involved
The cation is written first, then the anion
Li+ and O2- +1 -2
= -1 charge, need +
Li+ + O2- + Li+
= 0 charge, check!
Li2O

6. Oxidation Numbers
The charge on the ion is called its oxidation number or oxidation state
Atoms can have more than one oxidation number

7. Naming Monatomic Ionic Compounds
Monatomic- an ion made up of one type of atom (Li+, Na+, O2-, etc.)
The cation is given its full name
The anion uses the suffix –ide
For example, Li+ and O2-
Lithium Oxide
For example, Na+ and Cl-
Sodium Chloride

8. Think-Pair-Share: complete the chart by creating the formula unit
Think-Pair-Share: complete the chart by creating the formula unit. Leave room to also include the name of the compound. F-
O2-
N3-
S2-
Na+ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Na2O
Sodium Oxide
Na2S
Sodium Sulfide
NaF
Sodium Fluoride
Na3N
Sodium Nitride
LiF
Lithium Fluoride
Li2O
Lithium Oxide
Li3N
Lithium Nitride
Li+
Li2S
Lithium Sulfide
MgF2
Magnesium Fluoride
MgO
Magnesium Oxide
Mg3N2
Magnesium Nitride
MgS
Magnesium Sulfide
Mg2+
BeF2
Beryllium Fluoride
BeO
Beryllium Oxide
Be3N2
Beryllium Nitride
BeS
Beryllium Sulfide
Be2+

9. Guided Practice – reading charts
Compound
Lattice Energy (kJ/mol)
Melting Point (˚C) KI
-632
681 KF
-808
858
Which is a stronger bond? Why?
KF, more negative energy
Which has a higher melting point? KF
What is the relationship between ionic bond strength and melting point?
The stronger the bond, the higher the melting point!