Polarity and Molecular Shape Lab

Lewis Structures and Ball/Stick Models


Triangular Planar, 90-109.5, non-polar




Tetrahedron, 109.5, non-polar




Trianguler Planar, 109.5, non-polar



Octahedral, 90, non-polar



Tetrahedral, 109.5, non-polar


Linear, 90-109.5, polar



Tetrahedral, 109.5, non-polar

Daniel Webster
Kody Berget

Polarity and Molecular Shape Lab

A. Statement of the Problem
1. How shape affects polarity
2. How to make ball/stick models of Lewis structures of molecular formula

We know that a molecules electronegativity difference affects it's polarity. Now we are going to see how an atom's shape affects it so, by contructing ball/stick models based on the Lewis structures of the molescules


B. Hypothesis
1. I hypothesize that the shape of the covalently bonded molecule will affect the polarity of the molecule. I will build ball/stick models to help prove this. I know that electronegativity difference affects a molecules polarity, and I will find if the shape of a molecule will.

C. Objectives
1. Construct models of molecules from their Lewis Structures
2. Determine polarity of molecules
3. Predict polarity of molecules
D. Procedure
1. Built model for each of the listed molecules on the data table and drew the Lewis structures.
2.. Drew the structures on the paper, using solid lines to represent bonds in the plane of the paper, and dashed lines for bonds that point back or forward from the plane of the paper.
3. Determined whether the molecular shape, bond angle, if its polar or not, and resonance.
4. Materials:










E. Results
1. The pictures of the models are in the above section.
2.



















Conclusion:

The shape does affect the polarity of the model, and a molecule must have two halves to be polar, one negative and one positive. The real difference thought between polar and non-polar molecules lies in the electronegativity difference, which also affects the orientation of the molecules shapes and angles. In conclusion, this lab was really helpful way to help us understand a molecules shape, and its polarity.

1)Explain how water's shape causes it to be polar
The two ends are both positive and and the shape is not linear, but bent.
2)Describes how water's properties would be different if the molecules were linear instead of bent.
It would probably be less polar, and the shape would of course be linear.

Discussion:
Daniel: This lab really helped us understand Lewis structure and shapes in covalent molecules. It helped us understand the relation between an atoms shape and its polarity. In another lab, we could also shape ionic molecules to help us understand the difference between the two types of molecules, and maybe next time use an electonegativity chart to help us with our lab.
Kody: In addition to what Daniel said I would like to note how this lab really help me, being a kid with ADD. The book stuff really didn't click to good for me, I mean I understood it for the most part but not 100 percent. When we did this lab it was some hands on learning so I found it to be more easily understood.