CHM136 Problem Set 1 – Introduction of Organic Compounds: Carbon, Compounds,
and Nomenclature
To be attempted after completion of slide deck 1.
A. Shapes, Lewis Structures, Hybridization
1. Decide whether the following statements are TRUE or FALSE and provide a BRIEF (1-2 sentence)
explanation:
(a) Head-on overlap of two sp2 hybrid orbitals leads to a pi-bond. TRUE FALSE
Explanation:
Head-on overlap of two orbitals leads to a sigma-bond and side-on overlap leads to a pi-bond.
(b) A carbon-fluorine bond has a large dipole moment. TRUE FALSE
Explanation:
Carbon (EN = 2.5) and fluorine (EN = 4.0) have a large difference in their electronegativities that results in a
large bond dipole polarized towards fluorine.
(c) Carbon dioxide (CO2) has no net dipole. TRUE FALSE
Explanation:
CO2 is symmetrical so the two C=O bond dipoles are in opposite directions and thus cancel each other out.
(d) The carbon atom in carbon dioxide is sp hybridized. TRUE FALSE
Explanation:
The carbon atom in CO2 forms two sigma bonds to the oxygen atoms using two sp orbitals and two pi-bonds to
the oxygen atoms with two unhybridized p-orbitals.
PROBLEM SET 1 © DEPARTMENT OF CHEMISTRY UNIVERSITY OF TORONTO PAGE 1 OF 22
,Answer questions 2-5 about Compound 1 shown below:
N H H
C N H O
a H
O
Cl
Compound 1
2. How many valence lone pairs of electrons are present on Compound 1?
(a) (b) (c) (d) (e)
6 7 8 9 10
3. How many carbon atoms are best described as being sp2 hybridized in Compound 1?
(a) (b) (c) (d) (e)
6 7 8 9 10
4. The sigma bond between the carbon atoms labeled with an arrow on Compound 1 is best described
as being formed by the overlap of which type of orbitals?
(a) (b) (c) (d) (e)
C sp – C sp3 C sp2 – C sp3 C sp3 – C sp3 C sp2 – C sp2 C sp – C sp2
5. What is the molecular geometry of the carbon atom labeled “a” on the structure?
(a) (b) (c) (d) (e)
sp3 sp2 tetrahedral trigonal planar linear
PROBLEM SET 1 © DEPARTMENT OF CHEMISTRY UNIVERSITY OF TORONTO PAGE 2 OF 22
, Answer questions 6 and 7 about the structure of Pyrethrin (a natural insecticide made by
chrysanthemum Ulowers) shown below:
O
D
B O A
O
C
Pyrethrin
6. How many carbons are best described as sp2 hybridized in Pyrethrin?
(a) (b) (c) (d) (e)
6 8 10 12 14
7. Which of the following statements is TRUE about Pyrethrin?
(a) The angle labelled (A) is approximately 120°
(b) The carbon labelled (B) is secondary (2°)
(c) The oxygen labelled (C) is sp2 hybridized
(d) The carbon labelled (D) is sp2 hybridized
(e) The geometry of the carbon labeled B is trigonal planar
8. The following molecule is a derivative of moclobemide; a drug used to treat anxiety and depression.
O
N
H
Cl
The bond indicated by the arrow is best described as being formed from the overlap of which two
orbitals?
(a) N sp3 – C sp3
(b) N sp2 – C sp3
(c) N sp3 – C sp2
(d) N sp – C sp3
(e) N sp2 – C sp
PROBLEM SET 1 © DEPARTMENT OF CHEMISTRY UNIVERSITY OF TORONTO PAGE 3 OF 22
and Nomenclature
To be attempted after completion of slide deck 1.
A. Shapes, Lewis Structures, Hybridization
1. Decide whether the following statements are TRUE or FALSE and provide a BRIEF (1-2 sentence)
explanation:
(a) Head-on overlap of two sp2 hybrid orbitals leads to a pi-bond. TRUE FALSE
Explanation:
Head-on overlap of two orbitals leads to a sigma-bond and side-on overlap leads to a pi-bond.
(b) A carbon-fluorine bond has a large dipole moment. TRUE FALSE
Explanation:
Carbon (EN = 2.5) and fluorine (EN = 4.0) have a large difference in their electronegativities that results in a
large bond dipole polarized towards fluorine.
(c) Carbon dioxide (CO2) has no net dipole. TRUE FALSE
Explanation:
CO2 is symmetrical so the two C=O bond dipoles are in opposite directions and thus cancel each other out.
(d) The carbon atom in carbon dioxide is sp hybridized. TRUE FALSE
Explanation:
The carbon atom in CO2 forms two sigma bonds to the oxygen atoms using two sp orbitals and two pi-bonds to
the oxygen atoms with two unhybridized p-orbitals.
PROBLEM SET 1 © DEPARTMENT OF CHEMISTRY UNIVERSITY OF TORONTO PAGE 1 OF 22
,Answer questions 2-5 about Compound 1 shown below:
N H H
C N H O
a H
O
Cl
Compound 1
2. How many valence lone pairs of electrons are present on Compound 1?
(a) (b) (c) (d) (e)
6 7 8 9 10
3. How many carbon atoms are best described as being sp2 hybridized in Compound 1?
(a) (b) (c) (d) (e)
6 7 8 9 10
4. The sigma bond between the carbon atoms labeled with an arrow on Compound 1 is best described
as being formed by the overlap of which type of orbitals?
(a) (b) (c) (d) (e)
C sp – C sp3 C sp2 – C sp3 C sp3 – C sp3 C sp2 – C sp2 C sp – C sp2
5. What is the molecular geometry of the carbon atom labeled “a” on the structure?
(a) (b) (c) (d) (e)
sp3 sp2 tetrahedral trigonal planar linear
PROBLEM SET 1 © DEPARTMENT OF CHEMISTRY UNIVERSITY OF TORONTO PAGE 2 OF 22
, Answer questions 6 and 7 about the structure of Pyrethrin (a natural insecticide made by
chrysanthemum Ulowers) shown below:
O
D
B O A
O
C
Pyrethrin
6. How many carbons are best described as sp2 hybridized in Pyrethrin?
(a) (b) (c) (d) (e)
6 8 10 12 14
7. Which of the following statements is TRUE about Pyrethrin?
(a) The angle labelled (A) is approximately 120°
(b) The carbon labelled (B) is secondary (2°)
(c) The oxygen labelled (C) is sp2 hybridized
(d) The carbon labelled (D) is sp2 hybridized
(e) The geometry of the carbon labeled B is trigonal planar
8. The following molecule is a derivative of moclobemide; a drug used to treat anxiety and depression.
O
N
H
Cl
The bond indicated by the arrow is best described as being formed from the overlap of which two
orbitals?
(a) N sp3 – C sp3
(b) N sp2 – C sp3
(c) N sp3 – C sp2
(d) N sp – C sp3
(e) N sp2 – C sp
PROBLEM SET 1 © DEPARTMENT OF CHEMISTRY UNIVERSITY OF TORONTO PAGE 3 OF 22
