Organic Chemistry 101
Problems #1
Due Wednesday Sept. 8
Answers
Give the ground-state electronic configuration for each of the following atoms or ions. Use individual orbital populations
1.
showing electron spin.
a) P
c) K
b) O2-
1s2 2s2 2p6 3s2 3p3
3p
3s
d) Ca2+
1s2 2s2 2p6
1s2 2s2 2p6 3s2 3p6 4s1
1s2 2s2 2p6 3s2 3p6
2p
4s
3p
2s
3p
3s
3s
2p
2p
1s
2s
2p
1s
2s
2s
1s
1s
2.
Draw a proper Lewis structure for each of the following, including all formal charges. Use only octet structures where
possible. When more than one form is possible, choose the best (most stable) form.
H
a)
H
C
b)
.. O
.. :
c)
..
:S
H
(methoxide)
d)
H
C
+
N
.. N
H
e)
H
C
H
+
C C
H
N:
..
N
N
:O:
..
O
..
+
N
h)
.. _
:
O
..
H
H
H
:O:
C
C
.. _
O
.. :
H
H
(ammonium acetate)
.. :
O
..
H
f)
H
C
+
N
C:
H
H
(methyl nitrate)
(diazomethane)
H
+
(thiocyanate ion)
H
g)
C
-
H
(methyl isonitrile)
+
:N
O:
H
(nitrousonium ion)
(acetonitrile N-oxide)
3.
a) What is the hybridization of each non-hydrogen atom in 2c, 2f and 2g ?
b) What are the bond angles about each C and N in 2c and 2f and 2g?
2c) N – sp3(109.5°), CH3 – sp3(109.5°), C(O2) – sp2(120°);
2f) CH3 – sp3(109.5°), N – sp (180°), C- - sp (no real angle here but could say 180°)
2g) CH3 – sp3(109.5°), C(N) – sp, N – sp (180°), O – sp3
4.
Draw the two most reasonable resonance forms for 2d. Pick the one that would contribute most to the resonance hybrid and
explain your choice.
.. +
- .. N+ N
H C
H C
N N
H
1
H
2
Structure 1 is more stable and will contribute more to the resonance hybrid, since it has the negative
charge on the more electronegative atom nitrogen compared to carbon in 2
5.
Draw line-bond structural formulas for all the constitutional isomers with the formula C3H6O. These are actually
skeletal structures (bond-line structures).
O
OH
O
OH
O
O
O
H
6.
OH
Draw line-bond formulas for the two isomers (non-cyclic) of C3H4. What are the hybridization and bond angles about each
carbon in these two structures?
180°
H
H
H
sp
C
C
C
H
H
C
C
C
H
1
2
H
H
sp3
109.5°
sp2
120°
sp
180°
O
7.
Pyruvic acid is an intermediate in metabolism (C3H4O3). It’s structure has a CH3 group and two C=O groups. Draw the
O
C
H
line-bond formula for this compound.
C
C
H
8.
Which of the following formulas represent unstable/improbable species? Explain
H
a)
b)
c)
d)
9.
C2H7
C2H4Cl
C3H8N
C3H4ClN
OH
Improbable as carbon would need 5 bonds, or hydrogen 2 bonds.
Unstable as carbon would have a vacant valence
Unstable as C or N would have to have an odd valence. Formula requires odd # H
Yes this is possible
Draw the line-bond formula for the following bond-line structure.
H
H
C
N
C
O
H
C
C
N
C
H
C
C
C
H
H
O
H