1. Wrapping Up Covalent Bonding

2. Bond Disassociation Energy
When atoms combine, heat is released
The product is more stable that the reacts
Bond Dissociation Energy:
Then energy needed to break one mole of bonds
1 mole = 6.02 x 1023 bonds
Larger bond disassociation energy = stronger covalent bond
Examples:
Bond
Bond Disassociation Energy
C-C single bond
347 kJ/mol
H-H single bond
435 kJ/mol

3. Resonance An ozone molecule has two possible electron dot structures:
Ozone is a mixture of the two forms
Resonance structure:
A structure that occurs when it is possible to draw two or more valid electron dot structures that have the same number of e- pairs for a molecule or ion

4. Exceptions to the Octet Rule
The octet rule cannot be satisfied in molecules whose total number of valence e- is an odd number
Some molecules have fewer or more than a complete octet
Example: NO2

5. Other Oddities…
Boron
Example:
BF4
PCl5 (10 valence)

6. Naming Molecular Compounds

7. PreFixes Number Prefix 1 Mono- 2 Di- 3 Tri- 4 Tetra- 5 Penta- 6 Hexa-7
Hepta- 8
Octa- 9
Nona- 10
Deca-

8. Rules:
The name of a molecular compound indicates how many atoms of each type of element are present in the compound.
If there is only one atom of the first element, no prefix is used.
The prefix for one atom is used on the second element with mono-.
For example:
CO is carbon monoxide rather than carbon oxide.

9. Rules Continued Cation (1st) Anion (2nd) in the name
Example: Hydrogen (cation) Floride) (anion)
Anion takes the –ide ending

10. Let’s Practice
SO2
SF6
CCl4
NI3

11. More Practice…
CF4
SiO2
SO3
P4S3