Molecular Structures
Trevor B., Savannah A., Michael H.
Structural Formulas /
Lewis Structure
Structural Formulas are models using symbols of
elements to show positions of atoms when bonded.
Lewis Structures show estimated models of the
positions of both atoms and electrons in bonds.
What is the Structural formula of H2O?
What is the Lewis Structure of H2O?
Steps for drawing
Lewis Structures
1: Predict The Location of the Atoms
2: Determine The Number Of Electrons Available
3: Determine The Number Of Electrons used in Bonding
4: Draw bonded pairs
5: Determine electron pairs remaining
6: Draw in remaining atoms and determine middle atom
Structural
Formula/
Lewis Structure
Structural Formula of Water:
Lewis Structure of Water:
Types of Bonds
Single Bonds:
Double Bonds:
Triple Bonds
~Resonance~
Resonance: Condition where molecules can be
represented by more than one Lewis Structure
Examples: NO3 (Nitrate) and H3C2O (Acetate)
~Exceptions~
Odd Number Of Valence Electrons: Not enough
electrons to form full octets/bonds
Expanded Octet: More electrons than normal octet
Sub Octet: Less electrons than normal octet
Coordinate Covalent Bond: An atom donates 2
electrons to a hobo atom who needs them
Exception
Models
Sub Octet:
Expanded Octet:
Coordinated:
Resources/Activities:
http://chemsite.lsrhs.net/bonding/images/lewis%20do
t%20tutorial.swf
http://hyperphysics.phyastr.gsu.edu/hbase/pertab/perlewis.html
Resource: Book