Resonance, bond angle, conformation

Homework 1. Chem. 220, 2005, Fall Due Oct. 11


1. (21 pts) Predict the approximate bond angles in each of the following molecules and assign
formal charge on each atom (other than H).

H ..
.O . . .. .
. Cl .
.. . .
C C
. .. .. . .. .. . H2 C C CH 2
H H .O
. .. O.
. Cl
. .. Si Cl .
H H Cl .. ..
Carbene Radical
.O.
. .. . . Cl .
. .. .

H H

C
.. C
H H H H
Anion Cation

2. (20 pts) Give each atom the appropriate formal charge.
H
CH3 CH3
O
.
.
... .
H .O.. H3C N CH3
.. . .
H.. .
O H 3B N CH3
. H 2C CH2

CH3 CH3
3. (18 pts) Draw resonance structures for the following species (Here some of the H atoms are
not labeled, but they are there).
C C
_
CH3NO2, CO32-, C C C C CH2

CH 2+ C C

H C
C H H
C+
_ C
C C C C
C _
C C C C C C
+
C


H




4. (10 pts) Account for the fact that H3C-Cl (dipole moment 1.94 D) and H3C-F (dipole
moment 1.82 D) have almost identical dipole moments, even though fluorine has a much larger
electronegativity than chlorine.
5. (15 pts) Indicating the hybridization state in each atom of the following compounds and draw
the conformation of molecules.
H3 C H3C

H N CH3 H3C C N

H H


6. (16 pts) Arrange the following compounds in the order of decreasing acidity.
Cl



COOH COOH COOH Cl COOH

c d
Cl
a b