Download VSEPR practice problems answer key

VSEPR practice problems
– ANSWER KEY –
1)
2)
3)

Draw the 2-D LEWIS structure below the molecular formula.

Determine both electron-domain (ED) and molecular geometry.

Determine whether bond angles are ideal (90o, 109.5o, 120o, 180o) or distorted
due to lone pair – bonding pair repulsion.

From the overall molecular geometry and the presence and arrangement of
polar bonds (if any), determine if a molecule is polar. (Polarity does not apply to
polyatomic ions.)
PF3
PF5
SF4
ED geometry:
tetrahedral
Molecular geometry:
trigonal pyramidal
Bond angles:
< 109.5
Angles distorted?
yes
Is the molecule polar?
yes
ED geometry:
trigonal bipyramidal
Molecular geometry:
trigonal bipyramidal
Bond angles:
90, 120
Angles distorted?
no
Is the molecule polar?
no
ED geometry:
trigonal bipyramidal
Molecular geometry:
see-saw
Bond angles:
< 90, < 120
Angles distorted?
yes
Is the molecule polar?
yes
4)
5)
6)
7)
8)
SF6
CH3+
ClO-
ClO2-
ClO3-
ED geometry:
octahedral
Molecular geometry:
octahedral
Bond angles:
90
Angles distorted?
no
Is the molecule polar?
no
ED geometry:
trigonal planar
Molecular geometry:
trigonal planar
Bond angles:
120
Angles distorted?
no
Is the molecule polar?
n/a
ED geometry:
linear
Molecular geometry:
linear
Bond angles:
n/a
Angles distorted?
n/a
Is the molecule polar?
n/a
ED geometry:
tetrahedral
Molecular geometry:
bent
Bond angles:
< 109.5
Angles distorted?
yes
Is the molecule polar?
n/a
ED geometry:
tetrahedral
Molecular geometry:
trigonal pyramidal
Bond angles:
< 109.5
Angles distorted?
yes
Is the molecule polar?
n/a
9)
10)
11)
12)
ClO4-
KrF2
XeF4
XeF6
ED geometry:
tetrahedral
Molecular geometry:
tetrahedral
Bond angles:
109.5
Angles distorted?
no
Is the molecule polar?
n/a
ED geometry:
trigonal bipyramidal
Molecular geometry:
linear
Bond angles:
180
Angles distorted?
no
Is the molecule polar?
no
ED geometry:
octahedral
Molecular geometry:
square planar
Bond angles:
90
Angles distorted?
no
Is the molecule polar?
no
ED geometry:
octahedral
Molecular geometry:
octahedral
Bond angles:
90
Angles distorted?
yes, but not statically
Is the molecule polar?
no
http://en.wikipedia.org/wiki/Xenon_hexafluoride
The structure is best described in terms of a mobile electron pair that moves over the faces and edges of
the octahedron and thus distorts it in a dynamic manner.
13)
XeO3
ED geometry:
tetrahedral
Molecular geometry:
trigonal pyramidal
Bond angles:
< 109.5
Angles distorted?
yes
Is the molecule polar?
yes
14)
15)
16)
17)
18)
XeO2F2
CS2
NO3-
CO32-
BH3
ED geometry:
trigonal bipyramidal
Molecular geometry:
seesaw
Bond angles:
< 90, < 120, < 180
Angles distorted?
yes
Is the molecule polar?
yes
ED geometry:
linear
Molecular geometry:
linear
Bond angles:
180
Angles distorted?
no
Is the molecule polar?
no
ED geometry:
trigonal planar
Molecular geometry:
trigonal planar
Bond angles:
120
Angles distorted?
no
Is the molecule polar?
n/a
ED geometry:
trigonal planar
Molecular geometry:
trigonal planar
Bond angles:
120
Angles distorted?
no
Is the molecule polar?
n/a
ED geometry:
trigonal planar
Molecular geometry:
trigonal planar
Bond angles:
120
Angles distorted?
no
Is the molecule polar?
no
19)
20)
21)
22)
23)
XeF3+
BrF3
IF5
HCN
NH3Cl+
ED geometry:
trigonal bipyramidal
Molecular geometry:
T-shaped
Bond angles:
< 90, < 180
Angles distorted?
yes
Is the molecule polar?
n/a
ED geometry:
trigonal bipyramidal
Molecular geometry:
T-shaped
Bond angles:
< 90, < 180
Angles distorted?
yes
Is the molecule polar?
yes
ED geometry:
octahedral
Molecular geometry:
square planar
Bond angles:
< 90
Angles distorted?
yes
Is the molecule polar?
yes
ED geometry:
linear
Molecular geometry:
linear
Bond angles:
180
Angles distorted?
no
Is the molecule polar?
yes
ED geometry:
tetrahedral
Molecular geometry:
tetrahedral
Bond angles:
109.5
Angles distorted?
yes
Is the molecule polar?
n/a
24)
25)
26)
I3-
N3-
BHCl2
ED geometry:
trigonal bipyramidal
Molecular geometry:
linear
Bond angles:
180
Angles distorted?
no
Is the molecule polar?
n/a
ED geometry:
linear
Molecular geometry:
linear
Bond angles:
180
Angles distorted?
no
Is the molecule polar?
n/a
ED geometry:
trigonal planar
Molecular geometry:
trigonal planar
Bond angles:
120
Angles distorted?
yes
Is the molecule polar?
yes