1. Chapter VII

2. 7.1. Types of bonding

3. 7.2. Lewis structures, the octet rule
Lewis Structure: Representation of a molecule that shows how the valence electrons are arranged among the atoms in the molecule.
Bonding involves the valence electrons of atoms.
Example: Na●

5. Lewis structures of elements
Dots around elemental symbol
Symbolize valence electrons
Thus, one must know valence electron configuration

6. Rules for Lewis structures of molecules
Write out valence electrons for each atom
Connect lone electrons because lone electrons are destabilizing
Become two shared electrons
Called a “bond”
Check to see if octet rule is satisfied
Recall electron configuration resembling noble gas
In other words, there must be 8 electrons (bonded or non-bonded) around atom
Non-bonded electron-pair
Called “lone pair”

7. Let’s do some examples on the board
Duet rule H2
Octet rule F2 O2 N2

8. Lewis structures Example
Write the Lewis Structure for the following molecules:
H2O
CCl4
PH3
H2Se
C2H6

9. Lewis structures continued
C2H4
C2H2
SiO2

10. 7.3. Valence shell expansion and deficiency
A hypervalent molecule
(the phenomenon is sometimes colloquially known as expanded octet)
is a molecule that contains one or more main group elements formally bearing more than eight electrons in their valence shells.

11. Let us apply the rules to this case: Step 1: .
Example 1 6
Let us apply the rules to this case:
Step 1:
Total valence electrons = = 48
Step 2:
Total electrons needed for octets = 7 8 = 56
Step 3:
Total shared/bonding electrons = = 8.

12. For the next example, consider the ion ClO
Now, if we follow the rules of Lewis structures, we would obtain
Step 1:
Number of valence electrons  .
Step 2:
Number of electrons for octets  .
Step 3:
Number of shared electrons  .

13. 7.4. Resonance structure
Inchemistry, resonance or mesomerism  is a quantum superposition of wave functions built from Lewis structures as a way of describing delocalized electrons within certain molecules or polyatomic ions.
A molecule or ion with such delocalized electrons is represented by several contributing structures  (also called resonance structures or canonical forms).

16. 7.5. Formal charge calculations

19. 7.5. Molecular geometry and hybridization
All theory for explaining bonding
Valence bond theory
Valence Shell Electron Pair Repulsion Theory
Theory and Orbital Hybridization
Molecular Orbital (MO) Theory

20. .

22. Table 11.1 Composition and Orientation of Hybrid Orbitals.

25. 7.5. Molecular geometry and hybridization

26. 7.6. Polarity of molecules