10/7/2014
ALEKS Alex H. Yuan - 10/07/2014 7:51:12 PM EDT - Copyright © 2014 UC Regents and ALEKS Corporation
Alex H. Yuan - 10/07/2014 7:51:12 PM EDT
General Chemistry (First Semester) / Chem 110 FA 2014 – CH110 FA14 S25-36 (Dr.
Barber)
1.
Identifying carbon hybridization in simple organic molecules
Tag all the carbon atoms with pi bonds in this molecule.
H
H
C
C
C
H
H
You can solve this problem by using two general rules from the Valence Bond (VB) model
of chemical bonding.
The number of sigma and pi bonds around an atom can be deduced by adding up the
contributions from each single, double or triple bond, like so:
bond
contribution
single
sigma
double
sigma
pi
triple
sigma
pi
The hybridization of an atom can be determined by counting the number of sigma
bonds and lone pairs around it.
sigma bonds
plus lone pairs
hybridization
sp3
sp2
sp
https://secure.aleks.com/alekscgi/x/Isl.exe/1o_u-IgNsIkr7j8P3jH-lJiYsPgPQIfQokR4hWMNIe-wKsFh3XosSqwNh1O1sK3cu7UHLPc_x5q5Jb90xQ-XFp…
1/3
10/7/2014
ALEKS Alex H. Yuan - 10/07/2014 7:51:12 PM EDT - Copyright © 2014 UC Regents and ALEKS Corporation
Here is a summary of the results for carbon in its common bonding situations:
structure
hybridization
C
sp3
C
sp
C
sp
C
pi bonds
sp2
C
C
sigma bonds
sp3
sp2
This is a good table to commit to memory. If you do, you'll be able to quickly identify the
number of sigma and pi bonds, and the hybridization, of any carbon atom in any common
molecule. You'll just need to recognize one of the Lewis structure fragments from the first
https://secure.aleks.com/alekscgi/x/Isl.exe/1o_u-IgNsIkr7j8P3jH-lJiYsPgPQIfQokR4hWMNIe-wKsFh3XosSqwNh1O1sK3cu7UHLPc_x5q5Jb90xQ-XFp…
2/3
10/7/2014
ALEKS Alex H. Yuan - 10/07/2014 7:51:12 PM EDT - Copyright © 2014 UC Regents and ALEKS Corporation
column of this table.
Here is the answer.
H
H
C
C
C
H
H
Copyright © 2014 UC Regents and ALEKS Corporation
https://secure.aleks.com/alekscgi/x/Isl.exe/1o_u-IgNsIkr7j8P3jH-lJiYsPgPQIfQokR4hWMNIe-wKsFh3XosSqwNh1O1sK3cu7UHLPc_x5q5Jb90xQ-XFp…
3/3