MOLECULAR MODEL KITS – THE SHAPES OF MOLECULES
Purpose: To use a molecular model kit to determine the shapes of various molecules.
Materials: molecular model kit
Method: First of all, organize your molecular model kit by making sure you have the parts you
will need:
6 chlorine
green - 1 hole
18 hydrogen white (or silver)- 1 hole
6 oxygen
red
- 2 holes
5 carbon
1 nitrogen
1 boron
black - 4 holes
silver - 3 holes
purple - 3 holes
25 white or purple short sticks to represent single bonds
6 white, longer, flexible sticks – use two of these for each double bond
Please note that there will be other parts in the kit that you will not be using. They are
used by other classes that build different molecules. Keep them in your kit.
Next, do the following for each molecule in the observations and conclusions table:
1) Draw the Lewis Structure for the molecule in the space provided in the table.
2) Construct a model of the molecule using the parts from the molecular model kit.
Refer to the Lewis Structure to see how those parts should be connected.
3) Draw a diagram of the model in the space provided in the table. Consider the way
that the atoms are arranged in the model. Refer to the shapes in the section at the
bottom of this page. Then write down the name of the shape or the names of the
shapes which the molecule consists of.
(Please note that some of the molecules consist of two of the shapes joined together
by a shared bond. Also, it is the nature of this kind of kit that the double bonds curve
when they are used to join parts together. When you are drawing a diagram of or
naming the shape of a molecule with double bonds in it, realize that the double
bond goes straight between the atoms that it joins together.)
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The following list contains the names and representations of some of the common
shapes of molecules. A molecule can consist of one of the shapes or a combination of the
shapes. There are other shapes but the following ones are sufficient for introductory purposes.
trigonal
linear
pyramidal
or
bent or
angular
trigonal
planar
square
planar
tetrahedral
Observations and Conclusions:
Name______________________
A complete set of molecular models was built. ________ (Teacher must initial in this space.)
Substance Chemical
Formula
chlorine
gas
Cl2
water
H20
carbon
tetrachloride
CCl4
ammonia
NH3
boron
trihydride
BH3
hydrogen
peroxide
H202
ethanol
CH30H
carbon
dioxide
C02
ethene
C2H4
Lewis
Structure
Diagram of Shape and
Name(s) of Shape(s)