1. bond angles: the angles made by the lines joining
the nuclei of a molecule’s atoms
carbon dioxide
methane
formaldehyde
CO2
CH4
CH2O
180o
109.5o
120o

2. .. .. VSEPR electron domain: a region in which at least two
electrons are found
-- they repel each other because… they are all (–)
bonding domain: 2-to-6 e– that are shared by two
atoms; they form a… covalent bond
nonbonding domain: 2 e– that are located on a single
atom; also called a… lone pair
For ammonia, there are
three bonding domains and
one nonbonding domain.
NH3 N –H H– H ..
4 e– domains N H ..
Domains arrange themselves so
as to minimize their repulsions.

3. .. .. N The electron-domain geometry is one H
of five basic arrangements of domains.
-- it depends only on the total # of e– domains,
NOT the kind of each domain
The molecular geometry describes the
orientation of the atoms in space. ..
-- it depends on how many of each
kind of e– domain

4. Electron-Domain Geometry Possible Molecular Geometries
Total # of Domains
Electron-Domain Geometry
Possible Molecular Geometries 2 3 4 5 6
linear
linear (CO2)
trigonal
planar
trigonal planar (BF3), bent (NO2)
tetrahedral
tetrahedral (CH4),
trigonal pyramidal (NH3), bent (H2O)
trig. bipyramidal (PCl5), linear (XeF2)
seesaw (SF4), T-shaped (ClF3)
trigonal
bipyramidal
octahedral
octahedral (SF6), sq. pyr. (BrF5),
square planar (XeF4)

5. [ ] .. .. .. .. To find the electron-domain geometry (EDG) and/or
molecular geometry (MG), draw the Lewis structure.
Multiple bonds count as a single domain.
Predict the EDG and MG of each of the following.
[ ] Sn
–Cl
Cl– .. Cl –
SnCl3–
EDG: tetrahedral
MG: trig. pyramidal
26 e– .. O –O O= .. O O– O= O3
EDG: trig. planar
18 e–
MG: bent
Cl–Se–Cl ..
SeCl2
EDG: tetrahedral
20 e–
MG: bent

6. [ ] .. .. .. .. .. .. .. C= O O– 2– CO32– EDG: trig. planar (res.)
[ ] C= O O– .. 2–
CO32–
EDG: trig. planar
(res.)
MG: trig. planar
24 e– .. S –F F– F
SF4
EDG: trig. bipyr. ..
MG: seesaw
34 e– I .. F –F F–
IF5
EDG: octahedral ..
MG: sq. pyramidal
42 e– Cl –F F– .. F
ClF3
EDG: trig. bipyr. ..
MG: T-shaped
28 e–

7. [ ] .. .. .. .. I –Cl Cl– Cl – ICl4– EDG: octahedral MG: sq. planar
[ ] .. I
–Cl
Cl– Cl –
ICl4–
EDG: octahedral
MG: sq. planar
36 e–
For molecules with more than one central atom,
simply apply the VSEPR model to each part.
Predict the EDG and MG around the three interior
atoms of ethanoic (acetic) acid.
CH3COOH
PORTION
EDG MG
H–C–C–O–H .. H O
–CH3
tetra.
tetra.
C=O – ..
trig. plan.
trig. plan.
–OH ..
tetra.
bent

8. .. .. .. Nonbonding domains are attracted to only one nucleus;
therefore, they are more spread out than are bonding
domains. The effect is that nonbonding domains
(i.e., “lone pairs”) compress bond angles. Domains for
multiple bonds have a similar effect.
e.g.,
CH4 NH H2O
the ideal bond angle for the tetrahedral
EDG is 109.5o
COCl2 N H .. O H .. .. Cl
O=C C H
124.3o
104.5o
111.4o
107.0o
109.5o
124.3o
EDG = trig. plan.
ideal = 120o

9. Polarity of Molecules
A molecule’s polarity is determined by its overall
dipole, which is the vector sum of the dipoles of
each of the molecule’s bonds.
Consider CO2 v. H2S...
bond dipoles
bond dipoles S H ..
O=C=O ..
overall dipole =
zero
overall dipole =
(NONPOLAR)
(POLAR)

10. .. .. Classify as polar or nonpolar: PCl3 Cl– P –Cl polar BCl3 26 e–
Boron can be extracted by
the electrolysis of molten
boron trichloride. Boron is
an essential nutrient for
plants, and is also a primary
component of control rods
in nuclear reactors.