Honors Chemistry
Mrs. Klingaman
Chapter 9:
Molecular
GEOMETRY
Name: _______________________________________________
Mods: _____________________________
Chapter 9: Molecular Geometry
1. VSEPR theory enables us to predict the shape (molecular geometry) of molecules based on
the representative Lewis structure for each molecule. VSEPR stands for:
V- _________________________
P- _________________________
S- _________________________
R- _________________________
E- _________________________
2. VSEPR theory predicts the _________________________ of molecules based on the fact that
there is ____________________________ between the valence electrons surrounding the
central atom of molecule.
a. Bonding electrons pairs (single/double/triple bonds) take up space in a molecule and
repel one another
b. Nonbonding electron pairs also take up space in a molecule and repel electrons
__________________ strongly than bonding electron pairs
c.
As a result of this repulsion, the atoms in a molecule space themselves out
____________________________________ from one another as possible. ***
VSEPR  “The best arrangement of a given number of electron domains is the one
that minimizes the repulsions among them.”
3. Fill in the table below:
Name &
Formula
Lewis
structure
#
atoms
bonded
to
central
# nonbonding
electron
pairs
around
central
# of
domains
around
central
ABN type*
Molecular Shape
Methane
CH4
Ammonia
NH3
Water
H2O
* Write the ABN formula for each of these molecules.
A= central atom, B= number of attached atoms, N= Number of nonbonding electron pairs.
Use this notation to determine the shape of each molecule and fill in your answer in the table.
4. Molecular Polarity:

We know (from chapter 8) that polar _______________ result from having a significant
difference in the electronegativity of the 2 bonding atoms

When it comes to an entire molecule being polar, we consider both the polarity of the
____________ within the molecule as well as its 3D ______________
a. Molecules are either considered polar or nonpolar

A polar molecule is one which can visually be split in half to reflect one half of the
molecule that is more negative and one half that is more positive
b. Keys for finding Molecular Polarity:

Molecules that are three dimensionally symmetrical are often considered
_______________________
When the molecule is symmetrical, any polar bonds that may exist can cancel
out with one another

Molecules that are three dimensionally asymmetrical (not the same on all sides) are
often considered ____________________________.
Asymmetrical molecules are typically polar because their polar bonds cannot
cancel, thus one side of the molecule ends up being slightly more negative than
the other side, allowing the molecules to be “split” into two different poles!
Many times, a molecule with __________________________ electron pairs
on the central atom will end up being polar due to asymmetry.
5. Based on molecular shape and 3D symmetry, predict if the molecules below are polar or
nonpolar:

Methane =
______________________________

Ammonia =
______________________________

Water =
_____________________________
Now You Try:
Molecule
Lewis Dot Structure
# of
Atoms
Bonded
to
Central
# of
Nonbonding
e– Pairs
# of
domains
around
central
ABN type
Molecular Shape
ClO3–
CHO–
Based on molecular shape and symmetry, circle the correct polarity of each molecule:
ClO3– :
polar
or
nonpolar
CHO– :
polar
or
nonpolar
The chart at the front of this packet lists possible shapes of molecules, based on their Lewis
structure and ABN type.
Be comfortable with interpreting this information…like you just did!
The website below is excellent for visualizing the 3D orientation of each different molecular
geometry or for building example molecules
Online Simulator: http://phet.colorado.edu/en/simulation/molecule-shapes
VSEPR – Predicting Molecular Shapes
Directions: Fill in the table below by drawing the Lewis Structure of the molecule and determining its
ABN type and molecular shape
Molecule
CCl4
CO2
ClF3
XeBr2
Lewis Dot Structure
# of
atoms
bonded
to central
# of nonbonding e–
pairs on
central
# of
domains
around
central
ABN Type
Molecular Shape
Molecule
IBr5
PH5
NO2–
SCl6
XeF4
Lewis Dot Structure
# of
atoms
bonded
to central
# of nonbonding e–
pairs on
central
# of
domains
around
central
ABN Type
Molecular Shape
Molecule
HCN
CHBr3
HCl
O3
I3–
Lewis Dot Structure
# of
atoms
bonded
to central
# of nonbonding e–
pairs on
central
# of
domains
around
central
ABN Type
Molecular Shape