VSEPR Introductory Lab Activity
Procedure:
1) Draw the Lewis structure for each molecule.
2) Use the model kit to make a 3-D model of the structure using the correct number of atoms of each element.
Black = carbon
Blue = nitrogen
Green = halogens
Red = oxygen
White = hydrogen
3) Sketch an image of the 3-D model for each compound. Use crayons to indicate the types of atoms. Make sure
to illustrate in your drawing whether you used a single, double bond, or triple bond.
Formula
HI
OCl2
CH4
NH3
O2
Lewis dot structure
3-D drawing
(include measure of bond angles
on some of them)
VSEPR shape
CCl4
CH2O
NCl3
CH3Cl
N2
CO2
HCN
H2O
Summary:
Put the molecules into categories according to who has similar shapes.
Use the following criteria to aid you:
 How many atoms are around the central atom?
 Are the atoms all in the same plane or is the molecule 3d?
 What are the bond angles?
Under each category, list the characteristics that each of those molecules has in common with the others in the same
category.
The names of the VSEPR shapes are linear, tetrahedral, trigonal planar, trigonal pyramidal, and bent. Try to match up
those shapes with the categories you came up with.
Compare and contrast the following pairs (include comparisons between Lewis structures and 3D shapes) – include
similarities and differences:
H2O and CO2
NCl3 and CH2O
Teacher’s Guide
This is an introduction to VSEPR. Students should have prior knowledge of how to draw Lewis structures. I
use this before a lesson on molecular geometry and VSEPR.
Students draw the Lewis structures, then make the shapes with the ball and stick models and draw the shapes
from the models. If you want them to use a protractor to measure bond angles on a few, that helps them
recognize where those numbers come from when you teach that. I have them leave the VSEPR column blank
during the lab activity.
They then go through the questions with their group to notice the patterns – how the Lewis structures predict
the 3-d shape. Students really want to focus on single versus double versus triple bonds and I have to
remind them not to – to focus on the arrangements of the ATOMS around each other.
The lesson on VSEPR is based off of the summary questions at the end – we look at the 3D model, the Lewis
structure, and discuss it together. Then, after I’ve taught the VSEPR names, they fill in the last column as a
review.
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