Covalent Bonding Chemistry Worksheet With Answers Page 4
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671. C, O, H, S, N, F, Cl: These elements
are all nonmetals.
Critical Thinking
Concept Challenge
72. Answers will vary. Table 8.3 sug-
71.
Make a list of the elements found in Table 8.2 on
77.
The electron structure and geometry of the
gests there is no clear difference.
page 224. What do the elements that form cova-
methane molecule (CH
) can be described by a
4
The student’s argument could be
lent bonds have in common?
variety of models, including electron dot struc-
based on chemical properties,
ture, simple overlap of atomic orbitals, and
Is there a clear difference between a very polar
72.
orbital hybridization of carbon. Write the elec-
such as conductivity of the com-
covalent bond and an ionic bond? Explain.
tron dot structure of CH
. Sketch two molecular
pound in the liquid state.
4
Although the relative positions of the atoms are
73.
orbital pictures of the CH
molecule. For your
4
73. a. two covalent bonds to both
correct in each of these molecules there are one
2
first sketch, assume that one of the paired 2s
or more incorrect bonds in each of the electron
hydrogens; double bond between
electrons of carbon has been promoted to the
dot structures. Identify the incorrect bonds.
carbons
H
C C
H
empty 2p orbital. Overlap each half-filled atomic
Write the correct electron dot structure for each
orbital of carbon to a half-filled 2s orbital of
b. Fluorine and oxygen have only
molecule.
hydrogen. What is the predicted geometry of the
four electrons.
F O H
HwCwCwH
a.
CH
molecule, using this simple overlap
4
:F⎯O⎯H
b.
c. Halogens form one covalent
method? In your second sketch, assume hybrid-
c.
: I :::Cl :
I Cl
bond, not three.
ization of the 2s and 2p orbitals of carbon. Now
d.
H⎯N ::: N⎯H
what geometry would you predict for CH
?
d. Nitrogen forms three covalent
4
74.
Ethyl alcohol and dimethyl ether each have the
Which picture is preferable based on the facts
bonds, not four.
H
N N
H
same molecular formula, C
H
O. Ethyl alcohol
that all H⎯C⎯H bond angles in CH
are 109.5°
2
6
4
74. Ethyl alcohol can form intermolecu-
has a much higher boiling point (78°C) than
and all C⎯H bond distances are identical?
dimethyl ether ( 25°C). Propose an explanation
lar hydrogen bonds between its
There are some compounds in which one atom
78.
for this difference.
polar –OH groups, but dimethyl
has more electrons than the corresponding
What shape do you expect for a molecule with a
75.
noble gas. Examples are PCl
, SF
, and IF
. Write
ether can not form hydrogen bonds.
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6
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central atom and the following?
the electron dot structures of P, S, and I atoms
75. a. bent
a.
two bonding pairs of electrons and two non-
and of these compounds. Considering the outer
b. tetrahedral
bonding pairs of electrons.
shell configuration of P, S, and I, develop an
c. pyramidal
b.
four bonding pairs and zero nonbonding pairs.
orbital hybridization scheme to explain the
three bonding pairs and one nonbonding pair.
c.
76. False. The bond dissociation ener-
existence of these compounds.
76.
Is this statement true or false? “As the electrone-
gies exhibit no particular trend
Draw the electron dot structure of formic acid,
79.
gativity difference between covalently bonded
H
CO
. The carbon is the central atom, and all
and, in fact, are fairly constant.
2
2
atoms increases, the strength of the bond
the atoms are attached to the carbon except for
increases.” Use the table below to justify your
a hydrogen bonded to an oxygen.
answer.
Oxalic acid, C
H
O
, is used in polishes and rust
80.
2
2
4
removers. Draw the electron dot structure for
H
Bond
Electronegativity
Bond
77.
oxalic acid given that the two carbons are
Difference
Dissociation
Energy(kJ/mol)
bonded together but neither of the hydrogen
H
90
?
C ⎯ C
2.5
2.5
0.0
347
atoms is bonded to a carbon atom.
H C
H
H
H
C
90
C ⎯ H
Draw as many resonance structures as you can
H
2.5
2.1
0.4
393
81.
H
for HN
. (Hint: the three nitrogen atoms are
H
C ⎯ N
3.0
2.5
0.5
305
3
bonded in a row and the hydrogen atom is
C ⎯ O
3.5
2.5
1.0
356
109.5
109.5
bonded to a nitrogen atom at the end of the row
of nitrogens.)
H
C
H
Draw an electron dot structure for each mol-
82.
109.5
109.5
H
ecule and explain why it fails to obey the octet
The first sketch shows carbon’s three
rule.
p orbitals oriented at 90˚angles, re-
BeF
SiF
ClO
BF
XeF
a.
b.
c.
d.
e.
2
6
2
3
2
sulting in a pyramidal structure for
Assessment
249
the carbon atom with three hydro-
gen atoms. The 4th C-H bond, formed
with carbon’s 2s orbital and a hydro-
gen atom’s 1s orbital, is at unspecified
78.
81.
H N
N
N
H
N
N
N
F
Cl
F
angles to the other three C-H bonds.
F
F
Cl
Cl
F
F
The second sketch is tetrahedral. The
P
S
F
I F
82. a. Be has only 4 valence electrons.
F
F
bond angles in the first sketch are not
Cl
Cl
F
F
F Be F
F
O
all the same; some are 90°. The bond
3
P forms 5 hybrid orbitals (dsp
), S forms 6
c. Cl has only 7 valence electrons.
Cl
angles in the second sketch are all
O
2
3
hybrid orbitals (d
sp
), and I forms 7 hybrid
109.5° The second sketch is correct.
3
3
F
orbitals (d
sp
).
(Note: The wedge-shaped lines come
B
O
d. B has only 6 valence electrons.
out of the page; the dotted lines re-
F
F
79.
cede into the page.)
H
C O
H
e. Xe has 10 valence electrons.
F Xe F
O O
80.
H
O
C C
O
H
Covalent Bonding
249
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