Name____________________________________
Date:______________
Period:______
REVIEW Unit 2 Test (Chp 8,9): Bonding and Molecular Geometry
1.
How does oxygen demonstrate the “octet rule” when forming ionic bonds?
Oxygen atoms tend to _______________________________________________________________
_________________________________________________________________________________
2.
Ionic compounds of the greatest lattice energy form from cations that are __________ and
_________ and from anions that are _________ and __________.
___3. The electron-dot structure (Lewis structure) for which of the following molecules would have two
unshared pairs of electrons on the central atom?
(A) H2S
4.
(B) NH3
(C) CH4
(D) HCN
(E) CO2
Describe the trend in electronegativity in the periodic table.
___5. Of the bonds below, __________ is the least polar.
(A) Na-S
(B) P-S
(C) Na-Cl
(D) C-F
(E) Si-Cl
___6. Which of the following compounds has the least ionic character?
(A) PH3
(B) Na2O
(C) ZnS
(D) BeF2
(E) GaN
___7. Which of the following molecules has the shortest bond length?
(A) N2
(B) O2
(C) Cl2
(D) Br2
(E) I2
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Questions 8-11 refer to the following molecules.
(A) CO2
(B) CH4
(C) HF
(D) NH3
(E) F2
___8. Contains 2 π-bonds.
___9. Has the highest dipole moment.
___10. Has a molecular geometry that is trigonal pyramidal.
___11. Has the largest bond dissociation energy
___12. Which of the following has a zero dipole moment?
(A) HCN
(B) NH3
(C) SO2
(D) NO2
(E) PF5
CCl4, CO2, PCl3, PCl5, SF6
___13. Which of the following does not describe any of the molecules above?
(A) Linear
(B) Octahedral
(C) Square planar
(D) Tetrahedral
(E) Trigonal pyramidal
___14. Molecules that have planar configurations include which of the following?
I. BCl3
II. CHCl3
III. NCl3
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III
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___15. Types of hybridization exhibited by the C atoms in propene, CH3CHCH2, include which of the
following?
I. sp
II. sp2
III. sp3
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II, and III
___16. What is the molecular geometry of the SbCl5 molecule?
(A) tetrahedral
(B) T–shaped
(C) seesaw
(D) trigonal bipyramidal
(E) octahedral
17.
The hybridization of the carbon atom labeled x in the structure below is __________.
The H-C-H bond angle is __________.
The hybridization of the carbon atom labeled y in the structure below is __________.
The C-O-H bond angle is __________.
x
y
___18. There are __________ unhybridized p atomic orbitals in an sp3 hybridized carbon atom.
(A) 4
(B) 3
(C) 2
(D) 1
(E) 0
___19. In a molecule in which the central atom has six electron pairs around it, each of the six electron
domains is are directed toward the corners of
(A) a tetrahedron
(B) a square-based pyramid
(C) a trigonal bipyramid
(D) a square
(E) an octahedron
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___20. A typical triple bond…
(A)
(B)
(C)
(D)
(E)
21.
is longer than a single bond
is shorter than a double bond
is weaker than a single bond
has 1 sigma (σ) and 3 pi (π) bonds
consists of 6 electron pairs
Explain why the bond angle of SO2 is slightly less than 120o.
___22. Which of the following molecules contains bonds that have a bond order of 1.5?
(A) N2
(B) O3
(C) NH3
(D) CO2
(E) CH2CH2
23.
The molecular geometry of the XeF4 molecule is ___________________________.
24.
According to Valence Bond Theory, describe the hybridization of atomic orbitals and its results on
the ability of an atom to form bonds.
25.
Differentiate between ionic and covalent bonding.
26.
(single, double, triple)
Describe resonance and the delocalization of electrons as related to the character of a molecule’s bonds.
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Section II Free Response
CALCULATOR ALLOWED
Your responses to these questions will be graded on the basis of the accuracy and relevance of the
information cited. Explanations should be clear and well organized. Examples and equations may be
included in your responses where appropriate. Specific answers are preferable to broad, diffuse responses.
1. Answer the following questions about the structures of ions that contain only sulfur and fluorine.
(a) The compounds SF4 and BF3 are made to react to form an ionic compound according to the following
equation.
SF4 + BF3 → SF3BF4
(i) Draw a complete Lewis structure for the cation SF3+ in the compound SF3BF4. (1)
(ii) Identify the type of hybridization exhibited by sulfur in the SF3+ cation. (1)
(iii)Identify the geometry of the SF3+ cation that is consistent with the Lewis structure drawn in part
(a)(i). (1)
(iv) Predict whether the F-S-F bond angle in the SF3+ cation is larger than, equal to, or smaller than
109.5o. Justify your answer. (1)
(b) The compounds SF4 and CsF react to form an ionic compound according to the following equation.
SF4 + CsF → CsSF5
–
(i) Draw a complete Lewis structure for the SF5 anion in CsSF5. (1)
(ii) Identify the electron domain geometry exhibited by the SF4 molecule. (1)
–
(iii) Identify the geometry of the SF5 anion that is consistent with the Lewis structure drawn in
part (b)(i). (1)
–
(iv) Identify the formal charge of sulfur in the SF5 anion. (1)
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GeCl4
SeCl4
ICl4
–
ICl4
+
2. The species represented above all have the same number of chlorine atoms attached to the central atom.
(a) Draw the Lewis structure (electron-dot diagram) of each of the four species. Show all valence
electrons in your structures. (4)
(b) On the basis of the Lewis structures drawn in part (a), answer the following questions about the
particular species indicated.
(i) What is the Cl–Ge–Cl bond angle in GeCl4 ? (1)
(ii) Is SeCl4 polar? Explain. (1)
–
(iii) What is the geometric shape formed by the atoms in ICl4 ? (1)
(iv) What is the geometric shape formed by the atoms in ICl4+ ? (1)
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3. Using principles of chemical bonding and molecular geometry, explain each of the following
observations.
Lewis electron-dot diagrams and sketches of molecules may be helpful as part of your explanations. For
each observation, your answer must include references to both substances.
–
–
(a) The bonds in nitrite ion, NO2 , are shorter than the bonds in nitrate ion, NO3 . (2)
(b) The CH2F2 molecule is polar, whereas the CF4 molecule is not. (2)
(c) The atoms in a C2H4 molecule are located in a single plane, whereas those in a C2H6 molecule are not.
(2)
(d) The shape of a PF5 molecule differs from that of an IF5 molecule. (1)
(e) Draw two possible Lewis structures for the CH2O molecule and identify the most significant
structure. Justify your choice in terms of formal charge. (2)
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Answer Key
1.
2006 #7
2.
2006B #6
3.
2002B #6(a)-(d)
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