1. Bonding
Chapters 7-8

2. Octet Rule
Atoms tend to lose or gain electrons to achieve a full valence shell (8)
Exception: First Energy Level is full with 2 electrons

3. Electron Dot Structures
Diagrams that show valence electrons, usually as dots
AKA Lewis Electron Dot Diagrams
Rules
Start on any side
First two get paired together
Next three are separated
Fill in as needed O

4. Compounds Two Main Types of Compounds
Ionic
Molecular (Covalent)
Based on type of bonding involved

5. Bonding Bond Three Main Types
Shared or exchanged electrons that hold two atoms together
Three Main Types
Covalent
Ionic
Metallic

6. Covalent Bonds
Electrons are shared between two atoms to hold them together
Each atom will try to achieve a full valence shell
2 nonmetals
Two types of covalent bonds
Non-Polar Covalent – Shared equally
Polar Covalent – Shared unequally

7. Determining Bond Type
Whether electrons are shared equally or unequally is based on electronegativity difference between two bonding atoms
Nonpolar Covalent Bond
2 same Nonmetals (no difference in electronegativity)
Polar Covalent Bond
2 different Nonmetals (small difference in electronegativity)

8. Covalent Bonding H2 H H H
Single Bond

9. Covalent Bonding
H2O
Bond O H H
Bond H H

10. More Examples O2 O O O
Double Bond

11. More Examples N2 N N N
Triple Bond

12. More Examples Cl H
HCl
NH3 N H

13. More Examples
CH4
CO2 C H C C O

15. Bonding
Ionic Bond
Electrons are transferred from one atom to another (one loses, one gains)
Metal and nonmetal, NaCl
Large electronegativity difference

16. Properties Ionic Compounds
Most ionic compounds are hard, crystalline solids at room temperature
High melting points
Mostly soluble in water
Can conduct an electric current when melted or dissolved in water(aq).

17. Properties Covalent Compounds
Most molecular compounds tend to have relatively lower melting and boiling points than ionic compounds.

18. Ionic Compounds
NaCl

19. [ ] Cl Na+ Cl- - Dot Structures Shows valence electrons
Must show charge for Ions
NaCl Cl
[ ] -
Na+
Cl-

20. Dot Structures
MgO
Mg+2
O-2

21. Dot Structures
CaF2
Ca+2 F-

23. Network Solids
All atoms in a network solid are covalently bonded together
Network solids have very high melting and boiling points, since melting requires the breaking of many bonds throughout the compound.
Some of the strongest materials known to man are network solids.

24. Network Solids Diamonds (C) Graphite (C) Silicon Dioxide (SiO2)
Silicon Carbide (SiC)

25. Metallic Bonding
Bonding within metallic samples is due to highly mobile valence electrons
Free flowing valence electrons
“Sea of Electrons”

26. Bond Energy When two atoms form a bond, energy is released
Example: Cl + Cl  Cl2 + energy
Energy needs to be added to break a bond
Example: Cl2 + energy  Cl + Cl