VSEPR Worksheet
1)
What is the main idea behind VSEPR theory?
2)
For each of the following compounds, determine the molecular shapes and bond angles
for the central atom. Draw the Lewis dot formula to begin with and use the VESPR
Molecular Shape Chart to help you.
a)
carbon tetrachloride (hint: tetra means "four")
b)
BH3
c)
silicon disulfide (hint: di means two)
d)
C2H2
e)
PF3
VSEPR Molecular Shape Table
The table below summarizes the molecular and electron-pair geometries for different
combinations of bonding groups and nonbonding pairs of electrons on the central atom.
Sn = Steric Number
n
# of lone pair
electrons on
'central' atom
0
0
1
0
1
2
0
1
2
3
0
1
2
m
# of atoms bound
Sn = m Electronto the 'central'
Molecular
+n
pair
atom
Geometry
Geometry
2
2
linear
Linear
3
trigonal
trigonal
3
planar
planar
3
trigonal
2
bent
planar
4
4
tetrahedral tetrahedral
trigonal
3
4
tetrahedral
pyramidal
2
4
tetrahedral
bent
trigonal
trigonal
5
4
bipyramid
pyramidal
al
trigonal
4
5
bipyramid seesaw
al
trigonal
3
5
bipyramid T-shaped
al
trigonal
2
5
bipyramid
linear
al
6
6
octahedral octahedral
square
5
6
octahedral
pyramidal
square
4
6
octahedral
planar
Bond
Angle
Ex.
180
BeH2
120
BH3
less than
120
109.5
SO2
CH4
107
NH3
105
H2O
90, 120 and
180
NH3
90, 120 and
180
SF4
90 and 180
ClF3
180
PCl5
90 and 180
SF6
90 and 180
BrF5
90 and 180
XeF4