1. Chapter 14 pp. 373 - 386 Chapter 5 pp. 109 - 130
Ionic Compounds
Chapter 14 pp
Chapter 5 pp

2. Ionic Bonding
The forces of attraction that bind oppositely charged ion together
Q: Where does this attraction come from?
A: Positively charged ions and Negatively charged ions
Ionic compounds are electrically neutral
Also called salts

3. Formula Unit Chemical formula for ionic compounds
The smallest sample of an ionic compound that has the composition of the compound.
NaCl = 1 Na atom + 1 Cl atom

4. How do we know how many of each ion combine with another ion?
Remember, charges in an ionic compound must be neutral
Example
Br -1
AlBr3 Al3+ Br -1 e- e- e-

5. Let’s look at page 381
Try questions 9, 10, & 11

6. Properties of Ionic Compounds
When looking at ionic compounds we often will see that they are crystalline
A repeating dimensional pattern is formed…

7. Coordination Number
The number of ions of opposite charge that surround each ion in a crystal
Example
NaCl - 6

8. How do we know the coordination number?
X-ray crystallography
Patterns form when X-rays pass through a crystal onto X-ray film
Patterns are used to calculate the position of ions in the crystal

9. Electric Current
Some compounds conduct electric current when dissolved in solution.
Some compounds conduct an electric current in the molten state.
How does this happen?
When a current is passed through a solution cations and anions polarize or migrate to one electrode

10. Electric Current continued.
Ions move to the poles opposite to their charge.
The current is passed between two electrodes
Let’s take a look at a demonstration...

11. Metallic Bonding
Consist of the attraction of free-floating valence electrons for the positively charged metal cations
These electrons are floating around the cations
These moving electrons effect the physical and chemical properties of metals

12. Metallic Bonding cont’d.
Metals can change shape because of electrons surrounding the ions
Example: ductility
Ionic crystals break in “cleavage plains” because particles of the same charge come near each other, thus repelling one another

13. Metals and Electrical Conductivity
Metals conduct electricity because electrons are passed from one end of the metal to another
As e- are added to one end of the metal, more e- are leaving at the other end of the metal

14. Shapes of Metals Body-centered cubic Face-centered cubic
every atom has 8 neighbors
Face-centered cubic
every atom has 12 neighbors
Hexagonal close-packed
every atom has 12 neighbors, but different arrangement from Face-centered
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