Molecular Shapes Lab

Molecular Shapes and Polarity

Problem Statement:

• Determine Molecule Shapes

• Construct Models of Molecules

• Predict Polarity of Molecules

1. Background Information:

• The most common type of bond between two atoms is a covalent bond which is formed when two atoms share a pair of electrons. This bond will be nonpolar covalent if both atoms have the same electronegativity.On the other hand if these atoms have different electronegativities the bond between them is considered to be a polar covalent bond.
• Molecules made up of covalently bonded atoms may be polar or nonpolar. If the polar bonds are symmetrical around the central atom, the bonds are offest by each other thus making the molecule nonpolar. If the polar bonds are not symmetrical, the electrons will be pulled to one end of the molecule making it polar.
• Many physical properties of matter are the result of the shape and polarity of molecules. Water, for example, has unusual properties that can be explained by the shape of its molecule and the distribution of charge on the molecule.

Hypothesis

• This experiment will produce results showing nonpolar or polar makeups depending on each individual atom’s electronegativity.

Materials

• Molecule Model Kit

Lab Procedures

Draw the 3D structure of each molecule in table

Obtain needed materials.

Build a model for each of the molecules listed in the lab table

Take note of each model and list its shape, bond angle, Polarity, and resonance.

C3H8
-Tetrahedral- -109.5 degrees- -No- -No-

H20
-Angular- -90-109.5 degrees- -Yes- -No-



HF
-Linear- -180 degrees- -Yes- -No-



IF3
-Pyramidal- -90/109.5 degrees- -Yes- -No-

SF6
-Square Pyramidal- -90 degrees- -Yes- -No-

CO2
-Linear- -180 degrees- -Yes- -No-

SO3 [-2]
-SeeSaw- -120/90 degrees- -Yes- -Yes-

The shapes of the adjacent molecules corresponded with the octet rule which is fulfilled in each molecular shape.

Conclusion

Q- Based on the results of this experiment, list the molecules that would be water-soluble.
A- C2H4, H20, HF

Q- Explain how water's Shape causes it to be polar.
A- Its polarity is caused by the negative and positive being on different ends of the molecule.

Q- Describe how water's properties would be different if the molecules were linear instead of bent.
A- It would simply float away like a gas.