122_General Chemistry Exam 4

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General Chemistry Exam
100 pts
Name ______________________
Chemical Bonding and Molecular Architecture
Chapters 8, 9
Multiple Choice (2 pts each)
1. Of the atoms below, _?_ is the most electronegative.
A. Cl
B. N
C. O
D. Br
E. F
2.
Of the ions below, _?_ has a noble gas electron configuration.
A. K-1
B. S-3
C. Cl-1
D. O+2
E. I+1
3.
The chloride of _?_ should have the greatest lattice energy.
A. lithium
B. sodium
C. potassium
D. rubidium
E. cesium
4.
Of the following, _?_ cannot accommodate more than an octet of electrons.
A. As
B. S
C. P
D. I
E. O
5.
In the nitrite ion, NO2-1, _?_.
A. both bonds are double bonds
B. there are 20 valence electrons
C. both bonds are single bonds
D. one bond is a double covalent bond and the other is a single covalent bond
E. None of the above.
6.
A valid Lewis structure of _?_ cannot be drawn without violating the octet rule.
A. SO2
B. ICl5
C. NI3
D. SiF4
E. CO2
The diagram below shows the energy changes in the Born-Haber cycle for the formation
of crystalline lithium fluoride, LiF(s). The overall enthalpy change, as shown, is -608
kilojoules per mole.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
7.
The missing lattice energy for LiF is _?_.
A. -1128 kJ
B. 520 kJ
C. 88 kJ
D. -88 kJ
E. 1128 kJ
8.
When considering the resonance forms of a molecule or ion, _?_
A. there cannot be more than two resonance structures for a given specie.
B. all the resonance structures are observed in various proportions.
C. the observed structure is an average of the resonance forms.
D. the same atoms need not be bonded to each other in all resonance forms.
E. one always corresponds to the observed structure.
9.
Which of the molecules below has the shortest carbon-carbon bond distance?
A. C3H8
B. C2H6
C. C2H2
D. C2H4
10. The Lewis structure for the carbonate ion, CO3-2, reveals _?_ valence electrons.
A. 20
B. 22
C. 24
D. 26
E. 28
11. Of the molecules below, the bond in _?_ is the most polar.
A. HF
B. H2
C. HBr
D. HI
E. HCl
12. The electron domain geometry for a molecule or ion and its corresponding molecular
geometry are _?_.
A. never the same
B. not related
C. sometimes the same
D. always the same
13. Of the following species, which will have bond angles of 120°?
A. ClF3
B. NCl3
C. BCl3
D. PH3
E. All of these will have bond angles of 120°.
14. The structural formula for malonic acid, C3H4O4, is shown in the ball-and-stick
model below. The hybridization of the carbon atom (farthest right) in the structure is
_?_ and the C-C-O bond angle associated with this carbon is _?_.
A. sp3; 109.5°
B. sp3; 120°
C. sp2; slightly less than 120°
D. sp; 120°
QuickTime™ and a
E. sp; 109.5°
TIFF (Uncompressed) decompressor
are needed to see this picture.
15. The geometry associated with the central carbon in malonic acid (above) is _?_.
A. trigonal planar
B. tetrahedral
C. octahedral
D. trigonal bipyramidal
E. T-shaped
16. The fluoride ion, F-1, has the same electron configuration as which positive ion?
A. Ca+2
C. Mg+2
E. Sc+3
B. Li+1
D. K+1
17. The total number of lone pairs of electrons in the nitrogen molecule, N2, is _?_.
A. 1
B. 2
C. 3
D. 4
E. 5
18. The molecular geometry of sulfur hexafluoride, SF6, is _?_, and the hybridization of
sulfur in this molecule is _?_.
A. octahedral; sp3
B. tetrahedral; sp3
C. trigonal bipyramidal; sp3d2
D. octahedral; sp3d2
E. octahedral; sp3d
19. There are _?_ unhybridized p atomic orbitals in an sp-hybridized carbon atom.
A. 0
B. 1
C. 2
D. 3
E. 4
20. Using the VSEPR model, the molecular geometry of the central atom in XeF2 is _?_.
A. bent
B. linear
C. trigonal planar
D. trigonal pyramidal
E. tetrahedral
True or False (2 pts each)
21. Atoms surrounded by eight valence electrons tend to lose electrons.
22. The bond angles in the carbonate ion, CO3-2, are all 109.5°.
23. The possible molecular shapes associated with AB4 are tetrahedral, seesaw, and
square planar.
24. Lattice energy is the energy required to pull one mole of an ionic substance apart
into gaseous ions. The energy requirement increases as the charge on the ions
increases and as the ionic radii decreases.
25. According to valence bond theory, atoms are joined in bonding when orbitals
overlap to share electrons. Sigma () bonds result when orbitals overlap sideways
and pi (π) bonds result when orbitals overlap head-on or end-to-end.
Multiple Choice (2 pts each)
26. The type of compound that is most likely to contain a covalent bond is _?_.
A. a solid metal
B. one that is composed of a metal from columns 1 or 2 of the periodic table and a
nonmetal from column 16 or 17.
C. one that is composed of only nonmetals
D. held together by electrostatic forces between oppositely-charged ions
E. There is no general rule to predict covalency in bonds.
27. A triple covalent bond _?_.
A. consists of one  bond and two π bonds
B. consists of six electron pairs
C. consists of two  bond and one π bond
D. consists of three shared electrons
E. is longer than a single bond
28. According to valence bond theory, which orbitals overlap in the formation of the
bond in HBr?
A. 1s on H and 4p on Br
B. 1s on H and 3p on Br
C. 2s on H and 3p on Br
D. 1s on H and 4s on Br
E. 2s on H and 4p on Br
Consider the following molecules when answering question 29:
(i) PCl3
(ii) CCl4
(iii) TeCl4
(iv) XeF4
(v) SF6
29. For which of the following molecules is the molecular geometry the same as the
VSEPR electron domain arrangement?
A. (i) and (ii)
B. (i) and (iii)
C. (ii) and (v)
D. (iv) and (v)
E. (v) only
30. An electron domain consists of a _?_.
A. nonbonding pair of electrons
B. single bond
C. multiple bond
D. B and C only
E. A, B, and C
True or False (2 pts each)
31. Electrons in core orbitals contribute to the bonding of atoms.
32. A molecular may be nonpolar even if polar bonds exist within the molecule.
33. Atoms tend to gain, lose, or share electrons until they acquire eight valence electrons.
34. Atomic size has very little to do with an element’s electronegativity and the means by
which it bonds to other atoms.
35. The formal charge associated with bromine in the bromate ion, BrO3-1, is +2.
Lewis Structures (Questions 35-38 are valued at 8 points apiece.)
Draw (a) Lewis structures for the following molecules or ions below. Indicate for each
specie, (b) the electron domain geometry; (c) the molecular geometry; and (d) the
hybridization associated with the central atom.
36. (a) PCl5
(b)
(c)
(d)
37. (a) NO3-1
(b)
(c)
(d)
38. (a) TeCl4
(b)
(c)
(d)
39. (a) NH3
(b)
(c)
(d)
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