Lewis Structures and Molecular Shape

Shapes and Lewis Structures of Molecules

Background Information:

Everything is made out of different kinds of molecules. These molecules are made out of different combinations of atoms that are brought together by different kinds of bonds. We did this lab to better understand how these bonds are formed and what kind of molecules are made from these different bonds. These bonds occur when the electrons of an atom share themselves with those of another.

The best way to do this is to first make a lewis structure of the molecule you are inquiring. Lewis structures are diagrams that show the bonding between different atoms of a molecule, and the lone pairs of electrons that may exist in the molecule. It can be drawn for any covalently-bonded molecule. It was named after Gilbert N. Lewis, who introduced it in his 1916 article The Atom and the Molecule.

Reasoning For Experiment:

We did this experiment to better understand the way different molecules bond to one another and the shape they attain in the process. Analyzing the structure, you are able to obtain more information about its changes in properties and the polarity of the molecule.

Materials:

Here are is a picture of what we used to make our models for this lab

Procedure:

1. Build a model for each of the molecules listed on the data table on the back of this page.(Remember that some atoms can form multiple bonds.)
2. Draw the three-dimensional structure of each molecule in Table 1. (make a copy of Table 1 on your own paper) Use solid lines to represent bonds in the plane of the paper, and wedged lines for bonds that point of from the plane of the paper toward the viewer.
3. Note that the shape of each molecule in the third column of Table 1, the bond angles in column 4, whether or not they will be polar in column 5, and whether or not they exhibit resonance structure in column 6.

Results:


Here is a data table of 6 different molecules we decided to post. Included is the name of the Molecule, the Lewis Structure of it, the ball stick model, the shape, and the polarity of each. For the N2 molecule, we put in an incorrect structure in as an example. It should have a triple bond instead of a single bond. The SO3-2 Molecule was the only resonance structure included in this experiment. This means that it can have multiple ways of bonding and still result in to the same molecule and shape.

Click on Table for better clarity

Analysis Questions:

Explain how water's shape causes it to be polar.

Water is polar due to the fact that the hydrogen atoms only have their proton on the outside, where the electrons are bonded to the oxygen and the extra negative atoms of the oxygen are on the other side, making the molecule polar


Describe how water's properties would be different if the molecules were linear instead of bent.

If water was linear, there is a chance that the water would become non-polar, changing the way it reacts with other atoms and molecules.