Deck 9: Molecular Structure

Question 1

For which molecule will the electron-pair geometry be different than the molecular geometry?

A) NH₄⁺
B) CO
C) CH₄
D) BH₃
E) H₂O

Answer 1

H₂O

Question 2

Use the VSEPR model to predict the electron-pair geometry and the O-C-O bond angles for CO₃^2-.

A) tetrahedral, 90 ^$\circ$
B) triangular planar, 120 ^$\circ$
C) bent, 120 ^$\circ$
D) linear, 180 ^$\circ$
E) bent, 180 ^$\circ$

Answer 2

triangular planar, 120 ^$\circ$

Question 3

The VSEPR model attempts to ____ electron-pair ____.

A) eliminate; repulsions
B) minimize; collisions
C) minimize; repulsions
D) maximize; attractions
E) maximize; repulsions

Answer 3

minimize; repulsions

Question 4

For which molecule will the electron-pair geometry be the same as the molecular geometry?

A) NO₂^-
B) SeH₂
C) NF₃
D) ClF₃
E) ICl₆⁺

Question 5

According to the VSEPR model

A) The size of the electrons in the valence shell of a molecule determines the shape of the molecule.
B) The velocity of the electrons in the valence shell of a molecule determines the shape of the molecule.
C) The repulsion of electrons in the valence shell of a molecule determines the shape of the molecule.
D) The attraction of electrons in the valence shell of a molecule determines the shape of the molecule.
E) The mass of the electrons in the valence shell of a molecule determines the shape of the molecule.

Question 6

Use the VSEPR model to predict the electron-pair geometry and bond angles of PF₄⁺.

A) octahedral, 90 ^$\circ$
B) square planar, 90 ^$\circ$
C) tetrahedral, 109.5 ^$\circ$
D) triangular pyramidal, 90 ^$\circ$
E) tetrahedral, 90 ^$\circ$

Question 7

Which does not provide visual insight into the three-dimensional structure of a molecule?

A) VSEPR model
B) ball-and-stick model
C) space-filling model
D) computer-generated model
E) molecular orbital model

Question 8

Use the VSEPR model to predict the electron-pair geometry of O₃.

A) linear
B) tetrahedral
C) triangular bipyramidal
D) bent
E) triangular planar

Question 9

Which statement about a central atom that has six electron pairs is false?

A) The central must have an expanded octet.
B) The central atom can be a nonmetal.
C) The central atom must be from the third or subsequent periods.
D) The central atom can be a transition metal.
E) The central atom must have an octahedral molecular geometry.

Question 10

Use the VSEPR model to predict the geometry for two, three, four, five, and six electron pair domains, respectively.

A) linear, triangular pyramidal, tetrahedral, triangular bipyramidal, octahedral
B) linear, triangular planar, tetrahedral, square pyramidal, octahedral
C) bent, triangular pyramidal, tetrahedral, triangular pyramidal, octahedral
D) linear, triangular planar, tetrahedral, T-shaped, hexagonal
E) linear, triangular planar, tetrahedral, triangular bipyramidal, octahedral

Question 11

Use the VSEPR model to predict the electron-pair geometry of IF₂^-.

A) linear
B) bent
C) triangular bipyramidal
D) tetrahedral
E) T-shaped

Question 12

Use the VSEPR model to predict the electron-pair geometry, the molecular geometry, and the smallest approximate F-Cl-F bond angle of ClF₃.

A) triangular bipyramidal, T-shaped, 90 ^$\circ$
B) tetrahedral, triangular planar, 109.5 ^$\circ$
C) triangular bipyramidal, triangular pyramidal, 109.5 ^$\circ$
D) triangular bipyramidal, triangular planar, 120 ^$\circ$
E) triangular planar, triangular planar, 120 ^$\circ$

Question 13

Use the VSEPR model to predict the correct molecular shapes for ICl₃ and NO₂^-.

A) triangular planar, linear
B) triangular pyramidal, triangular planar
C) see-saw, linear
D) T-shaped, bent
E) triangular bipyramidal, triangular planar

Question 14

When sketching a molecule, an atom connected by a dashed line means that

A) the atom has a negative formal charge.
B) the atom has a negative ionic charge.
C) the atom lies behind the plane of the paper.
D) the bond is longer than indicated by the drawing.
E) some atoms have been left out for clarity.

Question 15

Use the VSEPR model to predict the X-A-X angles for the following compounds: CO₂, GeF₄, BCl₃.

A) 109.5 ^$\circ$ , 109.5 ^$\circ$ , 109.5 ^$\circ$
B) 109.5 ^$\circ$ , 90 ^$\circ$ , 90 ^$\circ$
C) 109.5 ^$\circ$ , 90 ^$\circ$ , 109.5 ^$\circ$
D) 180 ^$\circ$ , 109.5 ^$\circ$ , 120 ^$\circ$
E) 180 ^$\circ$ , 90 ^$\circ$ , 120 ^$\circ$

Question 16

In the VSEPR model, under which condition will the electron-pair geometry be the same as the molecular geometry?

A) in molecules with at least one lone pair of electrons on the central atom
B) in molecules with no lone pairs of electrons on the substituent atoms
C) in molecules with a central atom which is a nonmetal
D) in molecules with no lone pairs of electrons on the central atom
E) in molecules with more than one octet around the central atom

Question 17

How many lone pairs of electrons does the Lewis dot structure of H₂S have around its central atom and what is the shape of the molecule?

A) 0, linear
B) 0, bent
C) 1, triangular planar
D) 2, tetrahedral
E) 2, bent

Question 18

Use the VSEPR model to predict the molecular geometry of XeF₂.

A) linear
B) bent
C) tetrahedral
D) triangular bipyramidal
E) T-shaped

Question 19

Use the VSEPR model to predict the electron-pair geometry, the molecular geometry, and the H-N-H bond angle for NH₃.

A) square planar, square planar, 90 ^$\circ$
B) tetrahedral, triangular pyramidal 109.5 ^$\circ$
C) tetrahedral, square planar, 109.5 ^$\circ$
D) triangular bipyramidal, tetrahedral 90 ^$\circ$
E) tetrahedral, tetrahedral, 109.5 ^$\circ$

Question 20

Which of the following central atoms would be expected to accommodate more than four electron pairs in some of its compounds?

A) fluorine
B) boron
C) krypton
D) carbon
E) helium

Question 21

Use the VSEPR model to predict the electron-pair geometry and the molecular geometry of CO₂.

A) tetrahedral, linear
B) tetrahedral, tetrahedral
C) linear, bent
D) bent, linear
E) linear, linear

Question 22

Label the hybridization at C#1, C#2, C#3, and C#4 in the molecule. C1 C2 C3 C4

A) sp sp sp³ sp³d
B) sp sp sp² sp³
C) sp sp² sp² sp²
D) sp² sp² sp³ sp³
E) sp³ sp³ sp³ sp³

Question 23

The carbon-carbon bond in ethane, CH₃CH₃, results from the overlap of which of the following?

A) s atomic orbitals
B) p atomic orbitals
C) sp hybrid orbitals
D) sp² hybrid orbitals
E) sp³ hybrid orbitals

Question 24

Which molecule is polar?

A) BF₃
B) H₂Se
C) N₂
D) GeF₄
E) CO₂

Question 25

Which best describes the nature of the Si to Si bonds in a disilyne (Si₂H₂)?

A) three sigma
B) three pi
C) one sigma and one pi
D) two sigma and one pi
E) one sigma and two pi

Question 26

Which description of a pi bond is false?

A) orbital overlap above and below the bonding axis
B) sideways orbital overlap
C) orbital overlap is between parallel orbitals
D) greater orbital overlap than sigma bonds
E) electron density is not along the interatomic axis

Question 27

Which accurately describes a molecule with all polar bonds?

A) It is always a polar molecule.
B) It is never a polar molecule.
C) It may be a polar molecule.
D) It may be an ionic molecule.
E) It cannot be a nonpolar molecule.

Question 28

Which correctly lists the relative strengths of electron-pair repulsions?

A) bonding pair-bonding pair > lone pair-bonding pair > lone pair-lone pair
B) lone pair-lone pair > lone pair-bonding pair > bonding pair-bonding pair
C) lone pair-lone pair > bonding pair-bonding pair > lone pair-bonding pair
D) lone pair-bonding pair > lone pair-lone pair > bonding pair-bonding pair
E) bonding pair-bonding pair > lone pair-lone pair > lone pair-bonding pair

Question 29

Which compound does not have tetrahedral electron-pair geometry?

A) CCl₄
B) NO₂^-
C) H₃O⁺
D) PCl₃
E) H₂O

Question 30

Which has the smallest bond angle?

A)
B) H₂S
C) AsCl₃
D) SiF₄
E)

Question 31

Which molecule is nonpolar?

A) NCl₃
B) SO₂
C) PH₃
D) IF
E) CF₄

Question 32

The carbon-carbon p bond in ethylene, CH₂CH₂, results from the overlap of which of the following?

A) s atomic orbitals
B) p atomic orbitals
C) sp hybrid orbitals
D) sp² hybrid orbitals
E) sp³ hybrid orbitals

Question 33

Which substances have triangular pyramidal molecular geometry? I. nitrite ion
II. hydronium ion
III. sulfite ion
IV. carbonate ion

A) I and II
B) I and III
C) II and III
D) II and IV
E) III and IV

Question 34

If the molecular geometry of a substance is linear, the electron-pair geometry could be ____ with the central atom having ____ lone pairs.

A) triangular planar; one
B) tetrahedral; two
C) tetrahedral; four
D) triangular bipyramidal; two
E) triangular bipyramidal; three

Question 35

Which statement is false? A molecule may be polar if

A) it has polar bonds
B) it has does not have nonpolar bonds
C) it is not symmetrical
D) it has a permanent dipole
E) it has all nonpolar bonds

Question 36

Determine the hybridization around each central atom.

A) sp² sp² sp
B) sp² sp³ sp
C) sp² sp³ sp²
D) sp³ sp² sp²
E) sp³ sp³ sp²

Question 37

Which description of a sigma bond is false?

A) head-to-head orbital overlap
B) electron density always lies along the bonding axis
C) orbital overlap is always between hybridized orbitals
D) valence electrons are involved
E) orbital overlap is always along the interatomic axis

Question 38

In a molecule with triangular bipyramidal electron-pair geometry, where are any lone pairs on the central atom preferentially placed?

A) axially
B) equatorially
C) there is no preferential placement of lone pairs
D) there can be no lone pairs on the central atom to obtain a bipyramidal electron-pair geometry
E) the placement depends on the atoms involved

Question 39

How many atoms are bonded to the central atom when the molecular geometry is T-shaped?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 40

Determine the hybridization around each central atom.

A) sp sp² sp²
B) sp sp² sp³
C) sp² sp³ sp³d
D) sp² sp³ sp³d²
E) sp³ sp³ sp³

Question 41

Which substance experiences dipole-dipole interactions between its molecules?

A) N₂
B) ClF₃
C) SiH₄
D) CO₂
E) PCl₅

Question 42

Which interaction(s) exist(s) between CO molecules?

A) I only
B) II only
C) IV only
D) I and II
E) I and IV

Question 43

Because of London forces, molecules with ____ molecular weights tend to have ____ melting points.

A) lower; higher
B) higher; lower
C) higher; higher
D) even; higher
E) odd; higher

Question 44

Which of the molecules below undergo extensive hydrogen bonding?

A) HBr, HCl, HF, H₂O
B) H₂O, HF, NH₃
C) CH₄, H₂O, HF, NH₃
D) H₂S, H₂O, HCl, HF
E) AsH₃, NH₃, HF, H₂S

Question 45

Which compound experiences hydrogen bonding as one of its intermolecular forces?

A) O₂
B) SiH₄
C) AsH₃
D) HI
E) CH₃OH

Question 46

What is the major type of force that must be overcome to allow the boiling of carbon tetrachloride?

A) ion-dipole forces
B) dipole-dipole attractions
C) hydrogen bonding
D) covalent bonds
E) London forces

Question 47

Which interaction(s) exist(s) between ClF₃ molecules?
I. London forces.
II. ion-dipole forces
III. dipole-dipole attractions
IV. Hydrogen bonding

A) I only
B) I and III
C) II and III
D) III only
E) III and IV

Question 48

Characterize the polarity of these molecules, in the order written.

A) nonpolar, nonpolar, nonpolar
B) nonpolar, nonpolar, polar
C) polar, nonpolar, polar
D) polar, polar, nonpolar
E) polar, polar, polar

Question 49

Which compound has the lowest boiling point?

A) NH₃
B) CH₄
C) H₂O
D) HCl
E) H₂Se

Question 50

What is the major type of force that must be overcome to allow each of the processes below? I. the evaporation of propanal (CH₃CH₂CH₂OH)
II. the boiling of liquid CH₂Cl₂
III. the melting of solid Br₂
IV. the boiling of liquid BF₃

A) hydrogen bonding, London forces, dipole-dipole, dipole-dipole
B) hydrogen bonding, dipole-dipole, London forces, London forces
C) dipole-dipole, dipole-dipole, London forces, London forces
D) London forces, covalent bonding, dipole-dipole, dipole-dipole
E) London forces, London forces, London forces, London forces

Question 51

London forces exist

A) for all molecules.
B) only for molecules with nonpolar bonds.
C) only for molecules with polar bonds.
D) only for molecules with metallic bonds.
E) only for molecules with hydrogen bonding.

Question 52

Samples of which substance experience only London intermolecular forces?

A) HF
B) OF₂
C) PF₃
D) CCl₄
E) CH₃Cl

Question 53

Which molecule(s) is (are) polar?

A) I only
B) II only
C) I and II
D) I, II, and III
E) II, III, and IV