1. Ionic Bonding
By: Kiri Tamte-Horan

2. Before we talk about ionic bonds…
Understand that ionic bonding is a form of chemical bonds
Chemical bonds are formed by the joining of two or more atoms
Other forms of chemical bonds include:
Covalent Bonds
Metallic Bonds

3. What are ionic bonds?
Electrostatic forces that bind oppositely charged ions together
FOR EXAMPLE, NaCl
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4. What’s the difference between Ionic and Covalent bonding?
The difference is in the electronegativity
Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons
Most bonds are a combination of both Ionic and Covalent Bonds
“True” Covalent Bond  (pure covalent)
50:50 Bond 1.67
Greater than 1.67 is ionic (number varies)
Less than 1.67 is covalent (polar)

5. Coulomb’s Law where: F = force K = constant q1 & q2 = charges
d = distance between centers
*as the charges increase force increases
*as the distance between the centers increase force decreases

6. Lewis-dot Symbols They only depict valence electrons (octet)
Electrons are represented as dots
The number of valence electrons are shown by the dots surrounding the element
The electrons are added clockwise around the element
Remember the Aufbau Principle!
If you forget what that means, it means that you must fill the fill the lowest energy states first

7. Lewis-dot Symbols cont…
Lewis Dot Diagrams of Selected Elements

8. Properties of Ionic Bonds
Crystalline solids “crystal lattice” (unit cells)
Very high melting point
Do not conduct as a solid
But, do conduct as a liquid
Dissolve in Water
Commonly called salts

9. Ionic Reactions 2 Na Let’s bond Na and Cl!
The one valence electron from Na is transferred to Cl, making Cl have the electron configuration of a noble gas.
Na becomes 1+
Cl becomes 1- 2 Na

10. Born Haber Calculations
The Born Haber Cycle is a thermodynamic cycle that analyzes lattice energy
Lattice Energy is an estimate of the strength of the bonds in an ionic compound
To find the lattice energy we must use the BORN HABER CYCLE
Let’s find out what that is!

11. Born Haber Cycle Let’s use this example!
4Ga + 3 O2  2 Ga2O3
First we must DIVIDE through by the coefficient of the compound formed
In this case, that number is 2
So, 2Ga + 3/2 O2  Ga2O3
Now let’s go through the steps of the Cycle!

12. Step One
Vaporize the metal into the gaseous state using Heat of Sublimation
Since our metal is Ga, we must find the value for the Heat of Sublimation for Ga. In this case, the number is 262 KJ
Now, since there are 2 Ga, we must multiply 262 by 2!
The equation looks like this
2Ga(s)  2Ga(g)
Make sure you write in the states of matter!

13. Step Two
Ionize the metal atom to the state of charges using the Ionization Energy
We use the vaporized metal from Step One  2Ga(g)
For this step, we must first find out how many electrons Ga loses, which turns out to be three
Then, look up the Ionization energy for Ga, which is 2989 KJ
Like the previous step, we must multiply this number by two, since Ga has a coefficient of 2
2Ga(g)  2Ga e-
You get the 6e- from multiplying the coefficient by the number of electrons lost

14. Step Three
Dissociate the non-metal molecule into individual atoms by using the Bond Dissociation Energy
First, let’s look up the Bond Dissociation Energy for our non-metal, which is O2  495 KJ
3/2 O2(g)  30(g)
Since the first coefficient of O2 is 3/2, we must multiply our Bond Dissociation Energy, 495, by it

15. Step Four
Ionize the nonmetal atom by electron gain by using Electron Affinity Energy
Now we use the dissociated non-metal from step three
First we need to find out how many electrons O is gaining, which is 2
Then look up the value fore Electron Affinity Energy for O 737 KJ
Since our coefficient for O is 3, we must multiply this number by 3
3O + 6e-  3O 2-
To find the number of electrons, we multiply the number of electrons lost by O’s efficient

16. Step Five
Now we need to add together the equations from steps two and four to form the crystalline lattice structure. This releases the lattice energy
2Ga O 2-  Ga2O3(s)
Then we look up the lattice energy for Ga2O3, which is KJ

17. Finally!
Now, to find the heat of reaction, we must add up the sum of each step!
STEP ONE: 2 X 262 KJ
STEP TWO: 2 X 2989 KJ
STEP THREE: 3/2 X 495
STEP FOUR: 3 X 737 KJ
STEP FIVE:
SUM= KJ