1. Molecular Models and Chemical Bonds - Experiment

2. Performance Objectives
1.To construct models of molecules with single, double, and triple bonds. 2. To draw the structural formula for a molecule based on the molecular model. 3. To draw the electron dot formula corresponding to the structural formula. 4. To draw the structural and electron dot formulas for unknown molecular models.

3. Discussion
What is a chemical bond? A chemical bond is defined to be the attraction between two atoms in a molecule. What type of bonding give rise to the formation of a molecule? A covalent bonding. What is a covalent bond? A mutual sharing of valence electrons. The periodic table provide information for the valence electrons.

4. discussion
What type of bonding make-up Chloroform, CHCl3? A single bond. A single bond shares two electrons, and each connector represents an electron pair.
What types of bonding make-up Formaldehyde , H2CO ? A double and single bonds. A double bond shares two pairs of electrons. A molecular model is constructed using two connectors.
3. What types of bonding make-up Hydrogen Cyanide, HCN? A triple and single bond. A triple bond shares three pairs of electrons. A molecular model is constructed using three connectors to represent the triple bond.

5. Equipment and chemicals
Molecular Model Kit Directions for Using Molecular Models When constructing a model, a hole in a ball represents a missing electron that is necessary to complete an octet. Two balls joined by one connector, the connector represents a single bond. If two balls are joined by two connectors the bond is double bond. If two balls are joined by three connectors the bond is triple bond. One rigid connector – single bond Two flexible connectors – double bond and three flexible connectors - triple bond

6. Color coding elements
Yellow/White – Hydrogen (one hole) Black ball – Carbon (four holes) Red ball – Oxygen (two holes) Green ball – Chlorine (one hole) Orange ball – Bromine (one hole) Purple ball – Iodine (one hole) Blue ball – Nitrogen (three holes) If blue nitrogen ball has more than three holes, use a small peg or tape to fill the additional hole(s). All the holes in each ball must have a connector for a model to be built correctly.

7. Procedure
Construct models for each of the molecules on the following page. Sketch the molecular model in the Data Table, showing its three-dimensional structure.
2. Draw the structural formula corresponding to the molecular model.
3. Draw the electron dot formula corresponding to the structural formula. Complete the octet by surrounding each atom with 8 electrons (2 electrons for a hydrogen atom).
4. Verify each electron dot formula by summing the valence electrons for the molecule, using the periodic table. This sum should equal the total number of dots in the electron dot formula.

8. Procedure Molecular Models with Single Bonds
Molecular Models with Double Bonds
C. Molecular Models with Triple Bonds
Molecular Models with Two Double Bonds
E. Unknown Molecular Models