Physical Science
Lab #3
Three Dimensional Models of Covalent Molecules
DO NOT DO THIS LAB IN PEN!!!!! YOU WILL MESS IT UP
AND YOU DO NOT GET ANOTHER LAB PACKET.
Pre Lab Discussion
When learning how to draw structural formulas it is difficult to visualize the actual
geometry or shape of the molecule when it is drawn on paper. When you draw a molecule
on paper, you are only seeing a 2 dimensional representation of it. . Molecular model kits
allow you the opportunity to gain a more accurate perception of a molecule’s actual
geometry in three dimensions.
Purpose
The purpose of this lab is to use electron dot diagrams to predict the structural
formulas and use them to visualize a three dimensional representation for given molecules.
You will use molecular models to build the molecules to help you with this determination.
Equipment and Materials
Pencil
Molecular model kit
Model Kit color codes
Black = Carbon
White = Hydrogen
Green = Halogens (Cl, F, Br)
Blue = Nitrogen
Red = Oxygen/Sulfur
Short gray connector = single bond
long gray bond = double and triple bonds
Directions
Carefully reading ALL directions will help you NOT make common mistakes.
1. Use the colored “atoms” and gray connectors to “build” each atom on the following
table. MAKE SURE TO USE AS MANY CONNECTORS AS YOU HAVE BONDS OR SHAPES WILL BE
WRONG!!!!!!! Use the short gray connectors (bonds) for single bonds and use the long gray
connectors for double and triple bonds. The central atom of non-diatomic molecules are
underlined.
2. You must do the electron dot drawings and structural formulas for each molecule before
you build it OR YOU MAY DO IT INCORRECTLY!
OBSERVATIONS AND DATA (1)
Formula
Electron Dot Drawing
(1 point each)
1
H2
H  H
2
H2S
3
CH4
4
F2
5
NH3
6
HBr
7
N2
Name___________________________
Structural formula
(1 point each)
H
H
3D sketch of molecule
(2 points each)
OBSERVATIONS AND DATA (2)
8
O2
9
C2H2
10
C2H4
11
CO2
12
H2O2
13
CH2O
14
HCN
Name___________________________
QUESTIONS-make a separate page and answer in full sentences except for tables.
1. How is the formation for covalent bonds different from ionic bonds? (4 pts)
2. How do properties differ for covalent and ionic compounds? (4 pts)
3. What is a double bond and what is a triple bond? Explain fully! (4 pts)
4. What is the octet rule and how does it affect metals versus nonmetals? What is the
exception to it? (5 pts)
5. List three compounds each from this lab that contained double and triple bonds
Place them in a table like shown below (3 pts)
Bond Type
Compounds
Double bond(s)
Triple Bond(s)
6. What is an obvious way to know a molecule is non-polar? List 4 examples of non-polar
molecules from this lab. (5 pts)
ILLUSTRATION-make a separate page
On its own page and using electron dots (orange for Ca and Green for Cl), draw the
formation of the bond for CaCl2 making sure to draw the resulting structure. Make sure to
have the correct number of atoms shown.
CONCLUSION-make a separate page
Write a conclusion describing what you have learned from this lab. If you didn’t learn
anything, you probably didn’t follow directions. (10 pts)
Physical Science
LAB #3 Grade Sheet
Page Number
Description
Points
Possible
1
Title Page
2
2
Purpose, Equipment and Materials
(not model colors)
4
3
Observations and Data
52
4
Questions
25
5
Illustration
6
6
Conclusion
10
7
Grade Sheet
1
Totals
100
Points
Earned