1. Chemistry
Chapter 9
9.1/9.2 Notes Part 2

2. Review Covalent Bonds Sharing of valence electrons
Still atoms are trying to meet the octet rule
# of unpaired valence electrons decides how many bonds an atom can make
Use electron dot structures to see how many unpaired electrons there are in an atom
Bonds can be single, double, or triple

3. Single Bonds One shared pair of electrons Total of 2 e- in the bond
Also called a “sigma” bond
It just refers to the fact that there is a direct overlap between the outer energy levels of the atoms that are sharing e-

4. Multiple Bonds Double Bond Triple Bond 2 shared pair 4 e- total
1 sigma
1 pi
Triple Bond
3 shared, 6 e-
2 Pi (parallel overlap)
Double bond –
Red in the center = sigma
Green = Pi (above & below)

5. Strength of Bonds Bond Length Bond Dissociation Energy
The closer the nuclei are, the stronger the bond
More shared pair = closer the nuclei are
Bond Dissociation Energy
Amount of energy it takes to break a covalent bond
As bond length decreases, the bond dissociation energy increases

6. Covalent Compounds Properties Nonconductors Low melting
Low boiling point
Mostly gas at room temp
Solids are soft and brittle

7. Covalent Network Solids
Graphite V. Diamond
(allotropes)
Covalent Network Solids
Examples: diamond and Quartz
Covalently bonded in a crystal lattice (like an ionic compound) - a continuously bonded structure
Hard, rigid
High melting and boiling points
nonconductors

8. Lewis Structures
Electron diagrams of multiple atoms to show how they are arranged in molecules
Ex. H H2O Ammonia
Methane O2 CO2