CHE 1401 - Fall 2011 - Chapter 8
Homework 8 (Chapter 8: Basic concepts of chemical bonding)
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MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the
question.
1) Of the bonds below, __________ is the least polar.
A) Na, S
B) C, F
C) P, S
D) Si, Cl
1)
E) Na, Cl
2) Bond enthalpy is __________.
A) sometimes positive, sometimes negative
B) always negative
C) always zero
D) always positive
E) unpredictable
2)
3) Of the atoms below, __________ is the least electronegative.
A) F
B) Cl
C) Si
D) Ca
3)
E) Rb
4) Why don't we draw double bonds between the Be atom and the Cl atoms
in BeCl2?
A) That would result in more than eight electrons around beryllium.
B) There aren't enough electrons.
C) That would give positive formal charges to the chlorine atoms and a
negative formal charge to the beryllium atom.
D) That would result in more than eight electrons around each chlorine atom.
E) That would result in the formal charges not adding up to zero.
4)
5) A valid Lewis structure of __________ cannot be drawn without violating the
octet rule.
A) NF3
B) SiF4
C) SeF4
D) CF4
E) PO43-
5)
6) Which of the following does not have eight valence electrons?
A) Xe
B) Rb+1
C) ClD) Sr+1
6)
E) Ti+4
7) Given that the average bond energies for C-H and C-Br bonds are 413 and 276
kJ/mol, respectively, the heat of atomization of bromoform (CHBr3) is
__________ kJ/mol.
A) 1378
B) 1241
C) -689
D) -1378
E) 689
1
7)
8) Of the possible bonds between carbon atoms (single, double, and triple),
__________.
A) a double bond is stronger than a triple bond
B) a single bond is stronger than a triple bond
C) a triple bond is longer than a single bond
D) a single bond is stronger than a double bond
E) a double bond is longer than a triple bond
8)
9) In the nitrite ion (NO2-), __________.
A) one bond is a double bond and the other is a single bond
B) both bonds are double bonds
C) both bonds are the same
D) both bonds are single bonds
E) there are 20 valence electrons
9)
10) Most explosives are compounds that decompose rapidly to produce __________
products and a great deal of __________.
A) gaseous, gases
B) liquid, heat
C) soluble, heat
D) solid, gas
E) gaseous, heat
10)
11) A valid Lewis structure of __________ cannot be drawn without violating the
octet rule.
A) CO 2
B) PCl3
C) SO3
D) CCl4
E) ClF3
11)
12) Of the molecules below, the bond in __________ is the most polar.
A) HBr
B) HI
C) HF
D) H2
12)
E) HCl
13) Based on the octet rule, boron will most likely form a __________ ion.
A) B2+
B) B3C) B1+
D) B3+
E) B2-
13)
14) The oxidation number of phosphorus in PF3 is __________.
A) +1
B) -2
C) +3
D) +2
14)
15) Resonance structures differ by __________.
A) placement of atoms only
B) number of atoms only
C) placement of electrons only
D) number and placement of electrons
E) number of electrons only
2
E) -3
15)
16) Which two bonds are most similar in polarity?
A) BF and ClF
B) AlCl and IBr
C) ClCl and BeCl
D) OF and ClF
E) IBr and SiCl
16)
17) Which of the following has the bonds correctly arranged in order of increasing
polarity?
A) OF, NF, BeF, MgF
B) NF, BeF, MgF, OF
C) MgF, BeF, NF, OF
D) OF, BeF, MgF, NF
E) BeF, MgF, NF, OF
17)
18) Of the ions below, only __________ has a noble gas electron configuration.
A) KB) I+
C) O2+
D) S3E) Cl-
18)
19) Which of the following has eight valence electrons?
A) Na+
19)
B) Kr
C) ClD) Ti4+
E) all of the above
20) Of the atoms below, __________ is the most electronegative.
A) Cl
B) O
C) Br
D) F
20)
E) N
21) For resonance forms of a molecule or ion, __________.
A) the observed structure is an average of the resonance forms
B) the same atoms need not be bonded to each other in all resonance forms
C) there cannot be more than two resonance structures for a given species
D) one always corresponds to the observed structure
E) all the resonance structures are observed in various proportions
21)
22) Which atom can accommodate an octet of electrons, but doesn't necessarily
have to accommodate an octet?
A) H
B) C
C) B
D) O
E) N
22)
3
For the questions that follow, consider the BEST Lewis structures of the following oxyanions:
(i) NO2- (ii) NO3- (iii) SO32- (iv)SO42- (v) BrO323) There can be four equivalent best resonance structures of __________.
A) (i)
B) (ii)
C) (iii)
D) (iv)
E) (v)
23)
24) In which of the ions do all X-O bonds (X indicates the central atom) have the
same length?
A) none
B) all
C) (i) and (ii)
D) (iii) and (v)
E) (iii), (iv), and (v)
24)
25) As the number of covalent bonds between two atoms increases, the distance
between the atoms __________ and the strength of the bond between them
__________.
A) increases, increases
B) decreases, decreases
C) increases, decreases
D) decreases, increases
E) is unpredictable
25)
26) The chloride of which of the following metals should have the greatest lattice
energy?
A) cesium
B) lithium
C) sodium
D) potassium
E) rubidium
26)
27) A valid Lewis structure of __________ cannot be drawn without violating the
octet rule.
A) SO32B) NF3
C) CF4
D) BeH2
E) SO2
27)
4
28) The Lewis structure of the CO32- ion is __________.
A)
28)
B)
C)
D)
E)
29) A valid Lewis structure of __________ cannot be drawn without violating the
octet rule.
A) SiF4
B) NI3
C) SO2
D) ICl5
E) CO 2
5
29)
30) Of the following, __________ cannot accommodate more than an octet of
electrons.
A) I
B) P
C) S
D) O
E) As
30)
31) In the Lewis symbol for a sulfur atom, there are __________ paired and
__________ unpaired electrons.
A) 2, 4
B) 0, 6
C) 2, 2
D) 4, 2
E) 5, 1
31)
32) The electron configuration [Kr]4d10 represents __________.
A) Te+2
B) Sn+2
C) Sr+2
D) Rb+1
32)
E) Ag+1
33) Using the Born-Haber cycle, the ΔHf° of KBr is equal to __________.
A) ΔHf°[K (g)] + ΔHf°[Br (g)] + I1(K) + E(Br) + ΔHlattice
B) ΔHf°[K (g)] + ΔHf°[Br (g)] - I1 - E(Br) + ΔHlattice
C) ΔHf°[K (g)] - ΔHf°[Br (g)] + I1(K) - E(Br) + ΔHlattice
33)
D) ΔHf°[K (g)] - ΔHf°[Br (g)] - I1(K) - E(Br) - ΔHlattice
E) ΔHf°[K (g)] + ΔHf°[Br (g)] + I1(K) + E(Br) - ΔHlattice
34) In ionic bond formation, the lattice energy of ions ________ as the magnitude of
the ion charges _______ and the radii __________.
A) decreases, increase, increase
B) increases, increase, increase
C) increases, decrease, decrease
D) increases, decrease, increase
E) increases, increase, decrease
34)
35) The Lewis structure of N2H2 shows __________.
35)
A) a nitrogen-nitrogen single bond
B) each nitrogen has two nonbonding electron pairs
C) a nitrogen-nitrogen triple bond
D) each nitrogen has one nonbonding electron pair
E) each hydrogen has one nonbonding electron pair
36) Which of the following names is/are correct for the compound SnCl4?
A) tin (IV) tetrachloride
B) tin tetrachloride and tin (IV) chloride
C) tin chloride
D) tin (II) chloride and tin (IV) chloride
E) tin chloride and tin (II) tetrachloride
6
36)
37) The type of compound that is most likely to contain a covalent bond is
__________.
A) one that is composed of only nonmetals
B) one that is composed of a metal from the far left of the periodic table and a
nonmetal from the far right of the periodic table
C) held together by the electrostatic forces between oppositely charged ions
D) a solid metal
E) There is no general rule to predict covalency in bonds.
37)
38) Which of the following names is/are correct for the compound TiO2?
A) titanium dioxide and titanium (IV) oxide
B) titanium (IV) dioxide
C) titanium oxide and titanium (IV) dioxide
D) titanium oxide
E) titanium (II) oxide
38)
39) Dynamite consists of nitroglycerine mixed with __________.
A) damp KOH
B) TNT
C) diatomaceous earth or cellulose
D) potassium nitrate
E) solid carbon
39)
40) The central atom in __________ does not violate the octet rule.
A) KrF2
B) CF4
C) XeF4
D) ICl4-
40)
7
E) SF4