Essential Organic Chemistry, 2e (Bruice)
1
Chapter 1
1
Electronic Structure and Covalent Bonding
1
1)
1
Atoms with the same number of protons but different numbers of neutrons are called ______.
1
Answer:
1
isotopes
1
Section:
1
1.1
1
2)
1
What isotope of chlorine has the same number of neutrons as Argon-38?
1
A)
1
17Cl
1
B)
1
35Cl
1
C)
1
36Cl
1
D)
1
37Cl
1
E)
1
38Cl
1
Answer:
1
D
1
Section:
1
1.1
1
3)
1
Which statement is incorrect about the atomic number of an atom?
1
A)
1
It equals the number of protons in its nucleus.
1
B)
1
It equals the number of electrons outside the nucleus.
1
C)
1
It equals the sum of its protons and neutrons..
1
D)
1
It is a whole number.
1
E)
1
It is given on the Periodic Table.
1
Answer:
1
C
1
Section:
1
1.1
1
4)
1
Which of the following elements does this electronic configuration represent?
1s2 2s2 2p5
1
A)
1
F
1
B)
1
C
1
C)
1
N
1
D)
1
Al
1
E)
1
O
1
Answer:
1
A
1
Section:
1
1.2
1
5)
1
Which of the following is the electronic configuration of the element Fe?
1
A)
1
1s2 2s2 2p6 3s2 3p6 4s2 3d6
1
B)
1
1s2 2s2 2p6 3s2 3p8 3d6
1
C)
1
1s2 2s2 2p8 3s2 3p6 4s2 3d6
1
D)
1
1s2 2s2 2p6 3s2 3p6 4s2 4d6
1
E)
1
1s2 2s2 2p6 3s2 3p6 4s2 4p6
1
Answer:
1
A
1
Section:
1
1.2
1
6)
1
Ar, K+, Cl- are isoelectronic elements (elements with the same number of electrons). What orbital does the last electron occupy?
1
Answer:
1
3p orbital
1
Section:
1
1.2
1
7)
1
The atomic number of boron is 5. The correct electronic configuration of boron is ______.
1
A)
1
1s2 2s3
1
B)
1
1s2 2p3
1
C)
1
1s2 2s2 2p1
1
D)
1
2s2 2p3
1
E)
1
1s2 2s2 3s1
1
Answer:
1
C
1
Section:
1
1.2
1
8)
1
Which of the following statements correctly describes the third electron shell that surrounds the nucleus of an atom?
1
A)
1
The third shell contains only s and p atomic orbitals.
1
B)
1
The maximum number of electrons that can occupy the third shell is 18.
1
C)
1
The total number of atomic orbitals present in the third shell is 16.
1
D)
1
The third shell can contain f orbitals.
1
E)
1
none of the above
1
Answer:
1
B
1
Section:
1
1.2
1
9)
1
Which of the following describes a hydride ion?
1
A)
1
a negatively charged hydrogen ion containing a pair of electrons
1
B)
1
a positively charged hydrogen ion
1
C)
1
a hydrogen ion containing a single electron
1
D)
1
a negatively charged OH ion
1
E)
1
a proton containing an extra electron
1
Answer:
1
A
1
Section:
1
1.3
1
10)
1
Rank the following atoms in increasing electronegativity.
1
A)
1
N, Na, Si, O, C
1
B)
1
C, N, O, Na, Si
1
C)
1
O, N, C, Si, Na
1
D)
1
Si, C, N, O, Na
1
E)
1
Na, Si, C, N, O
1
Answer:
1
E
1
Section:
1
1.3
1
11)
1
Using the symbol δ+ and δ-, indicate the direction of the polarity in the indicated bond.
1
Answer:
1
1
Section:
1
1.3
1
12)
1
Covalent bonds may be polar or nonpolar. What property of the atoms forming a given bond accounts for this fact?
1
Answer:
1
electronegativity
1
Section:
1
1.3
1
13)
1
The compound methylamine, H3C-NH2, contains a C-N bond. In this bond, which of the following best describes the charge on the nitrogen atom?
1
A)
1
+1
1
B)
1
slightly positive
1
C)
1
uncharged
1
D)
1
slightly negative
1
E)
1
-1
1
Answer:
1
D
1
Section:
1
1.3
1
14)
1
Which of the compounds below bond predominantly via ionic bonding?
1
A)
1
KCl
1
B)
1
CF4
1
C)
1
NH3
1
D)
1
both A and B
1
E)
1
both B and C
1
Answer:
1
A
1
Section:
1
1.3
1
15)
1
What type of bonding is most important in CH3CH2CH2CH2CH2CH3?
1
A)
1
ionic
1
B)
1
hydrogen
1
C)
1
covalent
1
D)
1
polar
1
Answer:
1
C
1
Section:
1
1.3
1
16)
1
Which of the following contains polar covalent bonds?
1
A)
1
NH3
1
B)
1
Na2O
1
C)
1
H2
1
D)
1
KF
1
E)
1
both A and C
1
Answer:
1
A
1
Section:
1
1.3
1
17)
1
What is the name given for a species that contains a positively charged carbon atom?
1
A)
1
carbanion
1
B)
1
carbocation
1
C)
1
methyl radical
1
D)
1
carbon radical
1
E)
1
free radical
1
Answer:
1
B
1
Section:
1
1.4
1
18)
1
Which of the following is the most likely (i.e., most stable) electronic structure for C2H2?
1
A)
1
1
B)
1
1
C)
1
1
D)
1
HCCH
1
E)
1
1
Answer:
1
D
1
Section:
1
1.4
1
19)
1
Which of the following structures, including formal charges, is correct for diazomethane, H2CN2?
1
A)
1
:H2CNN:
1
B)
1
1
C)
1
1
D)
1
1
E)
1
1
Answer:
1
D
1
Section:
1
1.4
1
20)
1
What are the formal charges on nitrogen and the starred oxygen atom in the following molecule?
1
A)
1
N =-1, O = 0
1
B)
1
N =+1, O =-1
1
C)
1
N =+1, O =+1
1
D)
1
N =-1, O =-1
1
E)
1
N=+1, O = 0
1
Answer:
1
E
1
Section:
1
1.4
1
1
21)
1
Draw the Kekulé structure for each of the following:
a.CH3CH2OH b.CH3CHO c.(CH3)3C+
1
Answer:
1
1
Section:
1
1.4
1
22)
1
What is the formal charge on the phosphorus in the PO43- polyatomic ion?
1
A)
1
-3
1
B)
1
-2
1
C)
1
-1
1
D)
1
0
1
E)
1
+1
1
Answer:
1
E
1
Section:
1
1.4
1
23)
1
The formal charge on nitrogen in the compound below is ______.
1
A)
1
+2
1
B)
1
+1
1
C)
1
0
1
D)
1
-1
1
E)
1
-2
1
Answer:
1
B
1
Section:
1
1.4
1
24)
1
The Kekulé structure of pentane is shown below. Draw the condensed structural formula which corresponds to this Lewis structure.
1
Answer:
1
CH3(CH2)3CH3
1
Section:
1
1.4
1
25)
1
Draw condensed structures for the four compounds with formula C3H9N.
1
Answer:
1
CH3CH2CH2NH2
CH3CH2NHCH3
(CH3)2CHNH2
(CH3)3N
1
Section:
1
1.4
1
26)
1
Write a Lewis structure for the molecule given below.
CH2O
1
Answer:
1
1
Section:
1
1.4
1
27)
1
Expand the condensed structure below to show the covalent bonds and the lone-pair electrons.
(CH3)2CHCH2CHO
1
Answer:
1
1
Section:
1
1.4
1
28)
1
Draw the shape of a 2p orbital.
1
Answer:
1
1
Section:
1
1.5
1
29)
1
What is the name given to a three-dimensional region where an electron is found?
1
A)
1
nucleus
1
B)
1
ion
1
C)
1
sphere
1
D)
1
orbital
1
E)
1
cloud
1
Answer:
1
D
1
Section:
1
1.5
1
30)
1
How many distinct p orbitals exist in the second electron shell?
1
A)
1
0
1
B)
1
1
1
C)
1
2
1
D)
1
3
1
E)
1
4
1
Answer:
1
D
1
Section:
1
1.5
1
31)
1
Which describes the bond strength or bond dissociation energy?
1
A)
1
energy required to break a bond
1
B)
1
energy released when a bond breaks
1
C)
1
energy released when a bond is formed
1
D)
1
A and B
1
E)
1
A and C
1
Answer:
1
E
1
Section:
1
1.6
1
32)
1
Which statement is correct?
1
A)
1
Energy is released when a bond breaks.
1
B)
1
A sigma bond results from attraction of protons and electrons.
1
C)
1
Energy is released when a bond forms.
1
D)
1
Protons and electrons are repulsive.
1
E)
1
A carbanion is positively charged.
1
Answer:
1
C
1
Section:
1
1.6
1
33)
1
Both sigma (σ) and pi (π) bonds can be formed by overlapping p orbitals. Describe the difference.
1
Answer:
1
Sigma bonds are formed from the overlap of atomic orbitals along a circular axis of symmetrical nature, i.e., head-on overlap. All single bonds are sigma bonds.
Pi bonds are formed from the overlap of atomic orbitals along a non-symmetrical (parallel) axis, i.e., side-to-side overlap. Double and triple bonds are pi bonds.
1
Section:
1
1.6 and 1.8
1
34)
1
Choose the correct hybridization for the atom indicated in the molecule below.
CH3CH2CH2CH3
↑
1
A)
1
sp
1
B)
1
sp2
1
C)
1
sp3
1
D)
1
none of the above
1
Answer:
1
C
1
Section:
1
1.7
1
35)
1
What orbitals are used to form the covalent bonds in butane (CH3CH2CH2CH3)?
1
Answer:
1
The carbon-carbon σ bonds are formed by the overlap of two carbon sp3 hybrid atomic orbitals. The carbon-hydrogen σ bonds are formed by the overlap of a carbon sp3 hybrid atomic orbital and a hydrogen s orbital.
1
Section:
1
1.7
1
36)
1
Which of the following is a nonpolar molecule?
1
A)
1
HCl
1
B)
1
CH3Cl
1
C)
1
H2
1
D)
1
CO
1
E)
1
NH3
1
Answer:
1
C
1
Section:
1
1.3 and 1.7
1
37)
1
Which of the following is a correct formula for a compound?
1
A)
1
CH3CH2(CH3)2CH2CH3
1
B)
1
CH2CH2(CH3)CH2CH3
1
C)
1
CH3CH(CH3)CH2CH3
1
D)
1
CH3CH2(CH3)2
1
E)
1
C
1
Answer:
1
C
1
Section:
1
1.7
1
38)
1
Which of the following results from the combining of atomic orbitals?
1
A)
1
s orbital
1
B)
1
nonpolar molecule
1
C)
1
hybrid orbitals
1
D)
1
polar molecule
1
E)
1
sigma bond
1
Answer:
1
C
1
Section:
1
1.7
1
39)
1
How many electrons are involved in a carbon-carbon double bond?
1
A)
1
1
1
B)
1
2
1
C)
1
3
1
D)
1
4
1
E)
1
5
1
Answer:
1
D
1
Section:
1
1.8
1
40)
1
Which of the following describes a triple bond?
1
A)
1
two sigma bonds and two pi bonds
1
B)
1
three pi bonds
1
C)
1
one sigma bond and one pi bond
1
D)
1
two sigma bonds and one pi bond
1
E)
1
one sigma bond and two pi bonds
1
Answer:
1
E
1
Section:
1
1.9
1
41)
1
Which carbon(s) in the following molecule is (are) sp hybridized?
1
A)
1
carbon 1
1
B)
1
carbon 2
1
C)
1
carbon 1, 3
1
D)
1
carbon 4
1
E)
1
carbon 4, 5
1
Answer:
1
E
1
Section:
1
1.9
1
42)
1
Which of the following is an sp2 hybridized carbon?
1
A)
1
1
B)
1
∙ CH3
1
C)
1
1
D)
1
A and B
1
E)
1
A, B and C
1
Answer:
1
A
1
Section:
1
1.10
1
43)
1
What orbitals overlap to create the H-C bond in CH3+?
1
A)
1
sp3-sp3
1
B)
1
sp2-sp3
1
C)
1
s-p
1
D)
1
s-sp2
1
E)
1
s-sp3
1
Answer:
1
D
1
Section:
1
1.10
1
44)
1
The lone-pair electrons of the methyl anion occupy a ______orbital.
1
A)
1
s
1
B)
1
p
1
C)
1
sp
1
D)
1
sp2
1
E)
1
sp3
1
Answer:
1
E
1
Section:
1
1.10
1
45)
1
Explain why the water molecule has a bent shape and a bond angle less than 109.5°.
1
Answer:
1
The electron replusion between the two lone pairs of electrons on the oxygen of water causes the O-H bonds to squeeze close together.
1
Section:
1
1.11
1
46)
1
Which of the following is closest to the C-O-C bond angle in CH3-O-CH3?
1
A)
1
180°
1
B)
1
120°
1
C)
1
109.5°
1
D)
1
90°
1
E)
1
160°
1
Answer:
1
C
1
Section:
1
1.11
1
47)
1
Triethylamine [(CH3CH2)3N] is a molecule in which the nitrogen atom is ______hybridized and the CNC bond angle is ______.
1
A)
1
sp2; 109.5°
1
B)
1
sp2; 109.5°
1
C)
1
sp3; 109.5°
1
D)
1
sp3; 109.5°
1
E)
1
sp; 109.5°
1
Answer:
1
D
1
Section:
1
1.12
1
48)
1
The N-H bond in the ammonium ion, NH4+, is formed by the overlap of what two orbitals?
1
A)
1
sp3-sp3
1
B)
1
sp3-sp2
1
C)
1
sp2-sp2
1
D)
1
sp2-s
1
E)
1
sp3-s
1
Answer:
1
E
1
Section:
1
1.12
1
49)
1
Among the hydrogen halides, the strongest bond is found in ______and the longest bond is found in ______.
1
A)
1
HF; HF
1
B)
1
HF; HI
1
C)
1
HI; HF
1
D)
1
HI; HI
1
E)
1
HCl; HBr
1
Answer:
1
B
1
Section:
1
1.13
1
50)
1
Which bond in the following molecule is the shortest?
1
A)
1
bond 1
1
B)
1
bond 2
1
C)
1
bond 3
1
D)
1
bond 4
1
E)
1
bond 5
1
Answer:
1
E
1
Section:
1
1.14
1
51)
1
Which of the following species have tetrahedral bond angles?
1
A)
1
A, D and E
1
B)
1
A, D, E and F
1
C)
1
A and E
1
D)
1
D only
1
E)
1
A, B and E
1
Answer:
1
B
1
Section:
1
1.14
1
52)
1
The carbon-carbon double bond in ethene is ______and ______than the carbon-carbon triple bond in ethyne.
1
A)
1
stronger; shorter
1
B)
1
stronger; longer
1
C)
1
weaker; shorter
1
D)
1
weaker; longer
1
E)
1
stronger; more polar
1
Answer:
1
D
1
Section:
1
1.14
1
53)
1
Draw the structure of a molecule which contains only carbon and hydrogen atoms (only three of which are carbon) and in which two of the carbons are sp2 hybridized and the other is sp hybridized.
1
Answer:
1
H2CCCH2
1
Section:
1
1.14
1
54)
1
What is the CNN bond angle in the compound shown below?
1
A)
1
~60°
1
B)
1
~90°
1
C)
1
~110°
1
D)
1
~120°
1
E)
1
~180°
1
Answer:
1
D
1
Section:
1
1.14
1
55)
1
Why is the CH bond in ethene (H2CCH2) shorter and stronger than the CH bond in ethane(H3C-CH3)?
1
Answer:
1
The length and strength of a CH bond depends on the hybridization of the carbon atom. The more s character in the hybrid orbital used by carbon to form the bond, the shorter and stronger the bond. This is because an s orbital is closer to the nucleus than is a p orbital. Ethene uses carbon sp2 hybridized orbitals (1/3 s character) to make its carbon-hydrogen bonds while ethane uses carbon sp3 (1/4 s character) orbitals.
1
Section:
1
1.14
1
56)
1
What is the predicted shape, bond angle, and hybridization for +CH3?
1
A)
1
trigonal planar, 120°, sp2
1
B)
1
trigonal planar, 120°, sp3
1
C)
1
trigonal planar, 109.5°, sp2
1
D)
1
trigonal pyramidal, 120°, sp2
1
E)
1
trigonal pyramidal, 109.5°, sp2
1
Answer:
1
A
1
Section:
1
1.8, 1.10, and 1.14
1