NAME______________________________________________PERIOD_________
MOLECULAR GEOMETRY ACTIVITY
DIRECTIONS:
1.
2.
3.
4.
5.
Log onto a computer and navigate to this web page: www.phet.colorado.edu
Click “play with SIMULATIONS”, then select the CHEMISTRY simulations.
Open the “MOLECULE SHAPES” Simulation and run it.
Click MODEL.
Toggle the check boxes for: MOLECULE GEOMETRY, ELECTRON GEOMETRY, and SHOW BOND ANGLE.
Your task is to build molecules with varying numbers of DOMAINS. A DOMAIN is a group of electrons attached to a
central atom. Single bonds, double bonds and triple bonds are each a single domain. Also lone pairs are a domain.
according to the directions supplied. For each molecule, note its Molecular Geometry, ELECTRON GEOMETRY, and
its BOND ANGLE. Also make a simple sketch of the molecule. The molecule can be rotated for easier viewing. Once
you’ve completed each section, you’ll be asked to draw some conclusions.
TOTAL
Bonds on
DOMAINS Central
Atom
1
1
Lone
Pairs on
Central
Atom
O
2
2
0
1
1
3
0
2
1
1
2
4
0
3
1
3
4
2
1
Electron Geometry
Molecule
Geometry
Sketch and Bond Angle(s)
Note that NO bond angle exists unless
there are at least 2 different bonds to
central atom.
NAME______________________________________________PERIOD_________
MOLECULAR GEOMETRY ACTIVITY
TOTAL
Bonds on Lone
Electron Geometry Molecule
DOMAINS Central
Pairs on
Geometry
Atom
Central
Atom
5
5
0
Sketch and Bond Angle(s)
Note that NO bond angle exists unless
there are at least 2 different bonds to
central atom.
4
6
QUESTIONS:
1. For a given number of domains, which characteristic is common to EVERY molecule? _____________________
2. Sometimes the molecular geometry and the electron geometry are the same for a molecule, sometimes they are
different. Write two general rules that describe the pattern seen.
Molecular and Electron geometry of a molecule are the same when…
Molecular geometry differs from electron geometry for a molecule when…
NAME______________________________________________PERIOD_________
MOLECULAR GEOMETRY ACTIVITY
QUESTIONS CONTINUED…
3. Explain why it’s important in determining the geometry of a molecule to know about both bonds AND lone pairs
on the central atom?
4. Lewis dot structures are good tools for showing the arrangement of valence electrons in a molecule. They don’t
however convey correct information about the shape of a molecule. A student described the shapes of the
molecules shown below. Both are incorrect. Write an explanation for this student explaining what he did wrong
and giving the correct shape of each molecule based on VSEPR theory.
Lewis Structure
Student identified molecule geometry as…
Linear
WATER
Square planar
METHANE