Intro to Chemistry Chem1020 Lab
Molecular Models:
Lewis Structure and VSEPR Theory
Chemistry Department
Minneapolis Community & Technical College
1
Overview
• Part I
Molecular modeling kit
• Part II
Data sheet
2
Part I. Molecular Modeling Kit
Cover
Content
3
Atoms
4 holes
C, N, O, or F
4 holes
C, N, O, or F
4 holes
C, N, O, or F
1 hole
Hydrogen
(Note: The underlined element(s) is/are the preferred one(s)
representing that specific color.)
Attachments
One nonbonding
(or lone) pair
Single bond
(short and rigid)
One of the multiple bonds
(long and flexible)
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Part II. Data Sheet
You will obtain a data sheet at the beginning of the lab. The sheet includes
10 species that contain covalent bonds. For each species, you need to:
1. count the total number of valence electrons from all atoms present;
2. draw its Lewis structure;
3. make its 3D model using the molecular modeling kit;
4. determine the total number of electron regions around the central atom;
5. describe its electronic geometry in words;
6. determine the number of bonding regions around the central atom;
7. determine the number of nonbonding regions around the central atom;
8. describe its molecular geometry in words;
9. sketch its 3D structure.
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Example: H2O
Total valence e-
6 + 1×2 = 8 e-
Lewis structure
H
O
3D Model
H
# of bonding
regions around
central atom
# of nonbonding
regions around
central atom
Molecular
geometry
2
2
V-shape
(or bent)
Total e- regions
around central
atom
Electronic
geometry
4
Tetrahedral
Sketch
O
H
H
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• Dissemble all of molecule models and put pieces back to the
kit container according to the picture on page 3.
• Ask your instructor to sign you out….then you are ready to
leave.
• Finish the data sheet after the lab. Feel free to ask instructors
questions, but never ever copy other students’ answers.
• Turn in the data sheet the next time when you are expected to
come to the lab.
• Don’t forget to prepare for the next lab before you come next
time.
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