Chemistry lab molecular models

Organic Chemistry

Molecular Model Lab

Objective: To employ molecular models to investigate the bonding of the carbon atom in various types of organic compounds. The geometry, bond flexibility / rotation, and the arrangement and / or connectivity of various atoms around the carbon will be explored.

Atoms: The following atoms will be used for this experiment:

Carbon = black ball

Hydrogen = white ball

Oxygen = red ball

Nitrogen = blue ball

Halogen (F, Cl, Br, or I) = green ball

Terminology:

Hybridization: The combination of atomic orbitals of different types. The hybridization depends on the electron geometry of a molecule

Isomer: Different compounds or representation of a compound with the same molecular formula

Constitutional (Structural)

Stereoisomers (Geometric or Optical)

Conformational

Sigma bond (σ): A bond where the electron density lies between two nuclei, along the axis joining them, and is cylindrically symmetric about the axis.

Pi bond (П): A bond formed between overlapping p orbitals.

Procedure:

Students will make models of the various organic compounds. Each group will collect 5 carbons, 12 hydrogens, 1oxygen, 3 halogens and 1nitrogen. For all of the compounds listed, use the math concept to determine the number of bonds required. Draw out these structures.

1. Compound # 1: CH4

· Replace one of the H with a halogen. What is the formula of this new compound? Are the compounds the same?

· Replace another H with a halogen. What is the new formula? Describe how this compound is similar and different from the other compounds.

· Replace another hydrogen with a halogen. What is the formula for the compound? Define the polarity of the above three compounds.

2. Compound #2: C2H6

· Rotate the C-C bonds 60º (6x).

· Replace one of the H with a halogen. What is the formula with the halogen added to the structure?

· Replace another H on the same C with another halogen. What is the formula?

· Replace an H on both carbons with a halogen? What is the formula?

· Rotate this model C-C bond by 60º (6x)

· Compare this model to the previous model where both halogens were bonded to the same carbon. How do these two di-halogen molecules compare and differ?

3. Compound # 3: C3H6O

· Bring these atoms together according to their bonding capabilities. How many compounds can be formed from these atoms? Discuss their similarities (besides formula) and differences

4. Compound #4: C4H10

· Connect the atoms in the molecule. Rotate the C2-C3 bonds 60º (6x).

· Discuss the impact on the rotation for this molecule. Are there any rotations which you feel are favored and disfavored by the molecule?

5. Compound #5: C4H8

· Connect the atoms in this molecule.

· How many different compounds can come from this formula? Describe the similarities and differences between these compounds.

6. Compound #6: C4H6

· Connect the atoms in this molecule.

· How many different compounds can come from this formula? Describe the similarities and differences between these compounds.