Chem 127
Dr. Baxley
Bonding Energy, Lewis Structures, and VSEPR Worksheet
1. Calculate the enthalpy for the following reaction. Show all your work.
H
H C
Bond
C−C
C−N
C=N
C N
C−H
H−H
N−H
N−N
N−O
N=N
N
+ 2H
H
H
C
N
H
H
H
ΔH˚rxn = ?
Energy in kJ/mol
347
305
615
891
413
432
391
160
201
418
2. Fill in the tables below for each of the species shown. You must draw the Lewis Structure
first. The central atom does not necessarily have to follow the octet rule. Make sure to
include formal charge and possible resonance structures. Also remember that double and
triple bonds count the same as single bonds when determining geometries. There are a lot of
these in the book (CH 10 Homework), so do those for more practice!
a) CCl2H2
Total # of valence electrons:
Lewis Structure, complete with formal charges
(show any possible resonance structures too!)
Total # of electron groups around the central
atom:
Electron Pair Geometry:
# of bonded groups around the central atom
(connected to actual atoms):
VSEPR Sketch that shows 3-D shape of molecule
Molecular Geometry:
Bond Angle(s):
Polar or not?
Chem 127
Dr. Baxley
b) ClNO
Total # of valence electrons:
Lewis Structure, complete with formal charges
(show any possible resonance structures too!)
Total # of electron groups around the central
atom:
Electron Pair Geometry:
# of bonded groups around the central atom
(connected to actual atoms):
VSEPR Sketch that shows 3-D shape of molecule
Molecular Geometry:
Bond Angle(s):
Polar or not?
c) PF6−
Total # of valence electrons:
Lewis Structure, complete with formal charges
(show any possible resonance structures too!)
Total # of electron groups around the central
atom:
Electron Pair Geometry:
# of bonded groups around the central atom
(connected to actual atoms):
VSEPR Sketch that shows 3-D shape of molecule
Molecular Geometry:
Bond Angle(s):
Polar or not?
Chem 127
d) SbF4−
Total # of valence electrons:
Lewis Structure, complete with formal charges
(show any possible resonance structures too!)
Dr. Baxley
Total # of electron groups around the central
atom:
Electron Pair Geometry:
# of bonded groups around the central atom
(connected to actual atoms):
VSEPR Sketch that shows 3-D shape of molecule
Molecular Geometry:
Bond Angle(s):
Polar or not?
e) NO2−
Total # of valence electrons:
Lewis Structure, complete with formal charges
(show any possible resonance structures too!)
Total # of electron groups around the central
atom:
Electron Pair Geometry:
# of bonded groups around the central atom
(connected to actual atoms):
VSEPR Sketch that shows 3-D shape of molecule
Molecular Geometry:
Bond Angle(s):
Polar or not?
Chem 127
Dr. Baxley
Answer Key
1. –158 kJ
2. a. electron pair geometry: tetrahedral
molecular geometry: tetrahedral
bond angle: 109.5º
polar
Cl
H C Cl
H
b. electron pair geometry: trigonal planar
molecular geometry: bent
bond angle: <120º
polar
Cl N O
c. electron pair geometry: octahedral
molecular geometry: octahedral
bond angle: 90º
nonpolar
d. electron pair geometry: trigonal bipyramidal
molecular geometry: see-saw
bond angle: 90º & <120º
polar
F
F
S
F
F
e. electron pair geometry: trigonal planar
molecular geometry: bent
bond angle: <120º
polar
O N O
O N O