Imagining The Shapes Of Molecules Using Marshmallows printable pdf download

Name: ________________________________________________ Block: _____ Date: ______________

Imagining the Shapes of Molecules Using Marshmallows

Objective: By the end of this activity, you will be able to use valence shell electron pair repulsion theory (VSEPR) to

predict the molecular geometry of simple molecules

Background: In order to fully understand the nature of molecules, one must be able to imagine them in three

dimensions. Though Lewis dot structures are helpful, they’’re limited due to their two dimensionality. In this activity,

you will be using marshmallows and toothpicks to model certain familiar molecules in 3D. The molecules you will be

constructing will encompass the five molecular shapes you will be responsible for knowing in this class.

For each molecule in the chart below:

1. Fill in their respective Lewis Dot Structures in the space provided.

2. Obtain marshmallows to represent atoms and toothpicks to represent electrons.

3. Use the marshmallows and toothpicks to construct 3D models of the molecules. Make each toothpick count for

two electrons. It could be either a shared or unshared pair (i.e., a ““lone pair””). A lone pair would be a toothpick

with nothing at one end, while a bonding pair would be a toothpick with a marshmallow at both ends. Though

the two electrons in a pair will stay together, each pair will repel other pairs due to the electromagnetic force.

Be sure pairs of electrons (toothpicks) are as far apart as possible, except for double or triple bonds, which must

be together.

4. When you’’ve constructed a shape and everyone in the group agrees that the electron pairs are as far apart as

possible, you might want to check in with the teacher before continuing.

5. Once you’’re confident in each shape, come up with a name for it. Make it as descriptive of the shape as

possible. Put the name into the space provided in your chart.

6. Make a drawing of the shape of the molecule. Is there a way you can better express the 3D geometry of each

molecule’’s shape in two dimensions? Unless the molecule is flat, you may need to use some perspective tools in

your drawing.

Molecule

Lewis structure

Name of shape

Drawing of shape

Imagining The Shapes Of Molecules Using Marshmallows