CHEM 1411. Chapter 8.Molecular Geometry and Bonding

1 CHEM 1411. Chapter 8.Molecular Geometry and Bonding Theories (Homework) W

CHEM 1411. Chapter 8.Molecular Geometry and Bonding Theories (Homework) W

Multiple Choice

Identify the choice that best completes the statement or answers the question.

____ 1. The electrons in the outer shell of an atom are involved in bonding. Another name for the outer shell is ____.

a. valence shell

b. VSEPR shell

c. bonding shell

d. hybridized shell

e. Lewis shell

____ 2. What angle(s) are associated with a central atom that has trigonal bipyramidal electronic geometry?

a. 90 and 180

b. 120 and 180

c. 120

d. 90 and 120

e. 109.5

____ 3. Which one of the following molecules is polar?

a. P4

b. H2O

c. CO2

d. Cl2

e. N2

____ 4. The ONO bond angles associated with the nitrate ion, NO3, are all 120. The hybridization at the nitrogen

atom is ____.

a. sp3d

b. sp3

c. sp3d

2

d. sp

e. sp2

____ 5. Which of the following statements about polar molecules is false?

a. A molecule with polar bonds can be polar.

b. A molecule with 120 bond angles can be polar.

c. A molecule with only nonpolar bonds can be polar.

d. A molecule with polar bonds can be nonpolar.

e. A molecule with 180 bond angles can be polar.

____ 6. Which one of the following molecules has sp hybridization at the central atom?

a. BF3

b. SeF6

c. PF5

d. CF4

e. BeF2

____ 7. Which of the following molecules has 120 bond angles?


a. BCl3

b. H2S

c. BeI2

d. NF3

e. CH4

____ 8. Which of the following molecules has 120 bond angles?

a. CF4

b. BI3

c. H2O

d. BF4

e. NH4+

____ 9. Which of the following is a false statement about BF3?

a. The B atom does not satisfy the octet rule.

b. BF3 has trigonal pyramidal electronic geometry.

c. All three bond angles in BF3 are 120.

d. BF3 has trigonal planar molecular geometry.

e. Although the electronegativity difference between B and F is large (2.0 units), BF3 is a

covalent compound.

____ 10. Which response contains all the characteristics listed that should apply to silicon tetrafluoride, SiF4, and no

other characteristics?

I. tetrahedral

II. 120 bond angles

III. sp hybridized at C

IV. polar molecule

V. one unshared pair of electrons on Si

a. II and III

b. I

c. I and V

d. II, IV, and V

e. none of these

____ 11. Molecules such as NF3 are best described by assuming what kind of hybridization at the central atom?

a. sp

b. sp3d

2

c. sp3d

d. sp3

e. sp2

____ 12. Four of the following statements about the ammonia molecule, NH3, are correct. One is not. Which one?

a. The ammonia molecule is tetrahedral.

b. The bond dipoles re-enforce the effect of the unshared pair of electrons on the nitrogen

atom.

c. The bond angles in the ammonia molecule are less than 109.

d. Since nitrogen is more electronegative than hydrogen, the bond dipoles are directed

toward the nitrogen atoms.

e. The nitrogen atom can be described as utilizing sp3 hybrid orbitals in the ammonia


molecule.

____ 13. Four of the following statements about the ammonia molecule, NH3, and the nitrogen trifluoride molecule,

NF3, are correct. One is not. Which one?

a. The nitrogen atom can be described as utilizing sp3 hybrid orbitals in the nitrogen

trifluoride molecule.

b. The bond dipoles in NF3 are directed toward the more electronegative fluorine atoms.

c. Fluorine atoms are larger than hydrogen atoms, and therefore the bond angles in NF3 are

greater than in NH3.

d. The bond dipoles in NF3 oppose the effect of the unshared pair of electrons.

e. The NH3 molecule is more polar than the NF3 molecule.

____ 14. What is the hybridization at the central atom (P) of PF3Cl2?

a. sp

b. sp3d

2

c. sp3

d. sp3d

e. sp2

____ 15. How many unshared electrons are there in the highest energy level of phosphorus in the covalent compound

PF5? (HINT: Draw Lewis dot formula.)

a. five

b. two

c. three

d. none

e. eight

____ 16. Which of the following statements about AsF5 is false?

a. As has one lone pair.

b. As is sp3d hybridized.

c. Bonding angles are 90, 120 or 180.

d. The molecular geometry is trigonal bipyramidal.

e. The electronic geometry is trigonal bipyramidal.

____ 17. Which response includes all the polar molecules listed and no nonpolar molecules?

BCl3, AsF5, NF3, H2S

a. BCl3, NF3

b. AsF5, NF3, H2S

c. BCl3, AsF5

d. BCl3, H2S

e. NF3, H2S

____ 18. Which of the following statements about molecules with octahedral electronic geometry is false?

a. If there are two lone pairs of electrons on the central atom they will be 180 apart.

b. The molecular geometry is square planar if there are two lone pairs of electrons on the

central atom.

c. They are sp3d

2 hybridized.

d. The bond angles are 90, 120 or 180.

e. Octahedral geometry is symmetrical.


____ 19. Which of the following statements about multiple bonds is true?

a. A double bond consists of two sigma bonds.

b. A sigma bond results from the side-on overlap of p atomic orbitals.

c. sp2 hybridization in carbon is associated with one double bond and two single bonds.

d. sp3 hybridization in carbon is associated with one double bond and two single bonds.

e. A pi bond results from the head-on overlap of p atomic orbitals.

____ 20. How many sigma ()bonds and how many pi () bonds does the ethene molecule contain?

a. 5 , 1

b. 4 , 2

c. 5 , 2

d. 5 , 0

e. 8 , 2

____ 21. What is the hybridization of a carbon atom involved in a double bond?

a. sp3d

b. sp

c. sp2

d. sp3d

2

e. sp3

____ 22. How many sigma () bonds and how many pi () bonds does the acetylene molecule contain?

a. 3 and 2

b. 2 and 2

c. 3 and 1

d. 2 and 3

e. 5 and 1

____ 23. What is the hybridization of a carbon atom involved in a triple bond?

a. sp3d

b. sp3

c. sp

d. sp2

e. sp3d

2

____ 24. What is the geometry of a carbon atom involved in a triple bond?

a. tetrahedral

b. octahedral

c. trigonal planar

d. trigonal bipyramidal

e. linear

____ 25. Which of the following responses contains all of the true statements for ethyne?

I. The ethyne molecule has a double bond between its 2 carbon atoms.

II. The ethyne molecule has a triple bond between its 2 carbon atoms.


III. One pi bond is formed between the 2 carbon atoms by head-on overlap of the sp hybrid

orbitals.

IV. One sigma bond is formed between the 2 carbon atoms by head-on overlap of the sp2

hybrid orbitals.

V. The ethyne molecule is linear.

a. I and III

b. II and IV

c. I and IV

d. II and V

e. II and III

____ 26. Choose the species that is incorrectly matched with the electronic geometry about the central atom.

Ion / Electronic Geometry

a. BrO4 / tetrahedral

b. NO2 / trigonal planar

c. SO32

/ pyramidal

d. ClO3 / tetrahedral

e. ClO4 / tetrahedral

____ 27. Which molecule is incorrectly matched with the molecular geometry?

Molecule / Molecular Geometry

a. CCl4 / tetrahedral

b. PH3 / pyramidal

c. SO2 / linear

d. BeCl2 / linear

e. BBr3 / trigonal planar



a. SbH3 / pyramidal

b. SF4 / tetrahedral

c. CCl4 / tetrahedral

d. SO3 / pyramidal

e. SeF6 / octahedral



a. H2S / linear

b. BCl3 / trigonal planar

c. SF6 / octahedral

d. AsH3 / pyramidal

e. AsF5 / trigonal bipyramidal

____ 30. Which of the following molecules does not have tetrahedral electronic geometry?

a. ClO3


b. CCl2F2

c. SO32

d. ClO2

e. SF4

____ 31. Which, if any, of the compounds listed are not sp3 hybridized at the central atom?

I. CF4

II. H2O

III. SiF4

IV. CHCl3

V. NH3

a. III and IV

b. I, II, and III

c. II, IV, and V

d. III and V

e. all are sp3 hybridized

____ 32. Which, if any, of the compounds listed are not sp3d hybridized at the central atom?

I. BF3

II. AsI5

III. SF4

IV. BrF5

V. XeF4

a. III and IV

b. I, II, and III

c. I, IV, and V

d. III and V

e. all are sp3d hybridized

____ 33. Which species is incorrectly matched with bond angles?

Molecule / Bond Angles

a. SeO4 / 109.5

b. NH3 / 107

c. SnCl4 / 90, 120 (and 180)

d. ClO3 / slightly less than 109

e. HCl / 180

____ 34. What is the bond angle in a trigonal planar molecule or ion? a. 109° b. 72° c. 180° d. 120° e. 90°

____ 35. How many sigma and pi bonds are in the molecule pictured below?


a. eleven sigma bonds and two pie bonds b. five sigma bonds and eleven pie bonds c. thirteen sigma bonds and one pi bond d. thirteen sigma bonds and two pie bonds e. eleven sigma bonds and five pie bonds

Use the following Lewis structure for acetic acid to answer the following questions:

____ 36. The ideal value for the H-C-H bond angle about atom 1 is: a. 90

o b. 120

o c. 109.5

o d. 180

o e. 60

o

____ 37. Draw the Lewis structure for SbF3 to decide whether it is polar or nonpolar. a. polar b. nonpolar

____ 38. What does the following figure represent?

a. the overlap of a 1s orbital and a 2p orbital to form a pi bond

b. the overlap of two 1s orbitals to form a pi bond

c. the overlap of a 1s orbital and a 2p orbital to form a sigma bond

d. the overlap of two 2p orbitals to form a sigma bond

e. the overlap of two 2p orbitals to form a pi bond

____ 39. What does the following figure represent?

a. the overlap of a 1s orbital and a 2s orbital to form a pi bond


b. the overlap of two 2p orbitals to form a sigma bond

c. the overlap of two 1s orbitals to form a sigma bond

d. the overlap of two 1s orbitals to form a pi bond

e. the overlap of a 1s orbital and a 2s orbital to form a sigma bond

____ 40. What type of hybridization is represented in the figure below?

a. sp

3d b. sp

3 c. sp d. sp

2 e. sp

3d

2

Short Answer

Use the figures below to answer the following questions:

A B C

D E

1. Which of the figures represents sp hybridization?

2. Which of the figures represents sp2 hybridization?

3. Which of the figures represents sp3 hybridization?

4. Which of the figures represents sp3d hybridization?

5. Which of the figures represents sp3d

2 hybridization?

Other

1. The actual bond angle in the water molecule is about 104. Discuss the likelihood the electronic geometry of

the water molecule is square planar instead of tetrahedral.

2. Explain why sulfur can share 10 or 12 electrons, yet oxygen, in the same group, cannot.

3. Discuss how the Valence Bond theory explains why Be can make 2 and only 2 bonds.

4. In terms of the geometry of the orbitals, explain why a quadruple bond is not possible.


5. Double bonds count as only one region of high electron density instead of two. Comment on how the fact that

CO2 is nonpolar confirms this.

6. Consider a theoretical XeF6 molecule. What would you predict for hybridization of the orbitals? Can you

think of a possible geometry?


CHEM 1411. Chapter 8.Molecular Geometry and Bonding Theories (Homework) W

Answer Section

MULTIPLE CHOICE

1. ANS: A PTS: 1 OBJ: Define valence shell.

TOP: Valence Electrons

2. ANS: D PTS: 1

OBJ: Identify the angles between electron groups given the electron geometry.

TOP: Valence Shell Electron Pair Repulsion (VSEPR) Theory

3. ANS: B PTS: 1 OBJ: Identify the polar molecule.

TOP: Polar Molecules: The Influence of Molecular Geometry

4. ANS: E PTS: 1

OBJ: Identify the central atom hybridization given the bond angles around the central atom.

TOP: Valence Bond (VB) Theory

5. ANS: C PTS: 1

OBJ: Understand the connection between molecular geometry, polar bonds, and polarity of a molecule.

TOP: Valence Bond (VB) Theory

6. ANS: E PTS: 1

OBJ: Identify the formula consistent with the given central atom hybridization.

TOP: Linear Electronic Geometry: AB2 Species

7. ANS: A PTS: 1

OBJ: Identify the formula consistent with the given bond angles.

TOP: Trigonal Planar Electronic Geometry

8. ANS: B PTS: 1

OBJ: Identify the formula consistent with the given bond angles.


9. ANS: B PTS: 1 OBJ: Apply VSEPR and VB theory given the formula.


10. ANS: B PTS: 1 OBJ: Apply VSEPR and VB theory given the formula.

TOP: Tetrahedral Electronic Geometry: AB4 Species

11. ANS: D PTS: 1 OBJ: Identify the central atom hybridization given the formula.

TOP: Tetrahedral Electronic Geometry: AB3U Species

12. ANS: A PTS: 1 OBJ: Apply VSEPR and VB theory given the formula.


13. ANS: C PTS: 1 OBJ: Apply VSEPR and VB theory given the formula.


14. ANS: D PTS: 1 OBJ: Identify the central atom hybridization given the formula.

TOP: Trigonal Bipyramidal Electronic Geometry: AB5, AB4U, AB3U2, and AB2U3

15. ANS: D PTS: 1

OBJ: Determine the number of central atom lone pairs given a formula.


16. ANS: A PTS: 1 OBJ: Apply VSEPR and VB theory given the formula.



17. ANS: E PTS: 1 OBJ: Identify the formulas of polar molecules.


18. ANS: D PTS: 1

OBJ: Apply VSEPR and VB theory given the central atom electron geometry.

TOP: Octahedral Electronic Geometry: AB6, AB5U, and AB4U2

19. ANS: C PTS: 1 OBJ: Understand the VBT interpretation of multiple bonds.

TOP: Compounds Containing Double or Triple Bonds

20. ANS: A PTS: 1

OBJ: Determine the number of sigma and pi bonds given the Lewis structure.


21. ANS: C PTS: 1

OBJ: Identify the hybridization of an atom in a molecule given its bonding.


22. ANS: A PTS: 1

OBJ: Determine the number of sigma and pi bonds given the molecule name.

TOP: Compounds Containing Triple Bonds

23. ANS: C PTS: 1

OBJ: Identify the central atom hybridization given the bonding of an atom in a molecule.


24. ANS: E PTS: 1

OBJ: Identify the central atom geometry given the bonding of an atom in a molecule.


25. ANS: D PTS: 1 OBJ: Apply VSEPR and VB theory given the molecule name.


26. ANS: C PTS: 1

OBJ: Determine if a formula is consistent with the given electron geometry.

TOP: A Summary of Electronic and Molecular Geometries

27. ANS: C PTS: 1

OBJ: Determine if a formula is consistent with the given molecular geometry.


28. ANS: B PTS: 1



29. ANS: A PTS: 1



30. ANS: E PTS: 1

OBJ: Identify the formula not consistent with given electron geometry.


31. ANS: E PTS: 1

OBJ: Identify the formulas not consistent with the given central atom hybridization.


32. ANS: C PTS: 1

OBJ: Identify the formulas not consistent with the given central atom hybridization.


33. ANS: C PTS: 1

OBJ: Identify the formulas not consistent with the given bond angles.



34. ANS: D PTS: 1 DIF: Easy

OBJ: Identify the bond angle of a particular molecular geometry.

TOP: A Summary of Electronic and Molecular Geometries NOT: Dynamic Question

35. ANS: C PTS: 1 DIF: Easy

OBJ: Determine the number of sigma and pi bonds in the molecule given the Lewis structure.

TOP: Compounds Containing Double or Triple Bonds NOT: Dynamic Question

36. ANS: C PTS: 1 OBJ: Identify the ideal bond angle.

TOP: Valence Shell Electron Pair Repulsion (VSEPR) Theory NOT: OWL

37. ANS: A PTS: 1

OBJ: Draw the Lewis structure given the formula and infer the molecule polarity from the Lewis structure.

TOP: Polar and Nonpolar Molecules NOT: OWL

38. ANS: D PTS: 1 OBJ: Identify the correct description of sigma orbital overlap.

TOP: Valence Bond (VB) Theory NOT: OWL

39. ANS: D PTS: 1 OBJ: Identify the correct description of sigma orbital overlap.


40. ANS: B PTS: 1 OBJ: Identify the hybrid orbital.


SHORT ANSWER

1. ANS:

A

PTS: 1 OBJ: Identify the correct hybridized orbital.


2. ANS:

B



3. ANS:

C



4. ANS:

D



5. ANS:

E




OTHER

1. ANS:

Answer not provided.

PTS: 1 OBJ: Explain the factors responsible for the tetrahedral molecular geometry.

TOP: Valence Shell Electron Pair Repulsion (VSEPR) Theory | Valence Bond (VB) Theory

MSC: Conceptual question

2. ANS:


PTS: 1 OBJ: Explain the origin of the exceptions to the octet rule.

TOP: Valence Bond (VB) Theory | Lewis Structures MSC: Conceptual question

3. ANS:


PTS: 1 OBJ: Explain how VBT limits the number of bonds in a molecule.

TOP: Valence Bond (VB) Theory MSC: Conceptual question

4. ANS:


PTS: 1 OBJ: Describe the orbital atomic geometry required to form a quadruple bond.

TOP: Compounds Containing Double or Triple Bonds | Compounds Containing Triple Bonds | Valence

Bond (VB) Theory MSC: Conceptual question

5. ANS:


PTS: 1 OBJ: Explain why multiple bonds are treated as a single electron group in VSEPR

TOP: Valence Shell Electron Pair Repulsion (VSEPR) Theory MSC: Conceptual question

6. ANS:


PTS: 1

OBJ: Describe the central atom electronic and molecular geometry, and hybridization of theoretical

molecule.

TOP: Valence Shell Electron Pair Repulsion (VSEPR) Theory | Valence Bond (VB) Theory

MSC: Conceptual question

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CHEM 1411. Chapter 8.Molecular Geometry and Bonding