Deck 9: Molecular Geometry: Shape Determines Function

Question 1

Why does the seesaw molecular geometry (ss) have a lower energy than the trigonal pyramidal molecular geometry (tp) in an AB₄ molecule with a trigonal bipyramidal electron-pair geometry?

A)The ss geometry has fewer lone-pair bonding-pair interactions at 90^o.
B)The ss geometry has fewer lone-pair bonding-pair interactions at 120^o.
C)The ss geometry has fewer bonding-pair bonding-pair interactions at 120^o.
D)The ss geometry has fewer bonding-pair bonding-pair interactions at 90^o.
E)The ss geometry has fewer lone-pair lone-pair interactions at 90^o.

Answer 1

The ss geometry has fewer lone-pair bonding-pair interactions at 90^o.

Question 2

Which electron-pair geometry corresponds to a steric number of 6?

A)linear
B)trigonal planar
C)tetrahedral
D)trigonal bipyramidal
E)octahedral

Answer 2

octahedral

Question 3

Predict the bond angle indicated in SF₄.

A)120 ^$\circ$
B)90 ^$\circ$
C)greater than 120 ^$\circ$
D)less than 120 ^$\circ$
E)109.5 ^$\circ$

Answer 3

greater than 120 ^$\circ$

Question 4

A ________ geometry corresponds to a steric number of ________.

A)linear; 1
B)trigonal planar; 2
C)tetrahedral; 3
D)trigonal bipyramidal; 5
E)octahedral; 4

Question 5

Which one of the statements A-D about electron-pair geometry and molecular geometry is not correct?

A)The electron-pair geometry identifies the relative positions of the bonding regions of electrons and the lone pairs of electrons around a central atom in a molecule.
B)The molecular geometry identifies the relative positions of the atoms around a central atom in a molecule.
C)If there are no lone pairs, then the electron-pair geometry and the molecular geometry are the same.
D)The molecular geometry differs from the electron-pair geometry when the number of atoms around the central atom is smaller than the number of regions of electron density.
E)Statements A-D are all correct.

Question 6

Which statement about VSEPR theory is not correct?

A)VSEPR is an acronym for valence-shell electron-pair repulsion.
B)In VSEPR theory, the shape or geometry of a molecule is determined by electron-electron repulsion.
C)The steric number of a central atom is the sum of the number of bonds and lone pairs around the atom.
D)The steric number has five values from 2 to 6.
E)The molecular shape or geometry always is the same as the electron-pair geometry.

Question 7

Which electron-pair geometry corresponds to a steric number of 5?

A)linear
B)trigonal planar
C)tetrahedral
D)trigonal bipyramidal
E)octahedral

Question 8

Select which of the following repulsive interactions between electron pairs would be smallest.

A)
B)
C)
D)
E)All involve equal repulsive forces.

Question 9

In VSEPR theory, molecular geometry is determined by ________

A)electron-proton attractive forces.
B)electron-electron attractive forces.
C)electron-electron repulsive forces.
D)proton-proton repulsive forces.
E)electron-nucleus attractive forces.

Question 10

Which statement about VSEPR theory is not correct?

A)The molecular shape or geometry is determined by the positions of the atoms in the molecule.
B)In VSEPR theory, the shape or geometry of a molecule is determined by electron-electron repulsion.
C)The steric number of a central atom is the sum of the number of bonds around the atom.
D)The steric number has five values from 2 to 6.
E)The electron-pair geometry is determined by the positions of the bonds and lone pairs in a molecule.

Question 11

Which electron-pair geometry has the lowest electron-electron repulsive forces?

A)linear
B)trigonal planar
C)tetrahedral
D)trigonal bipyramidal
E)octahedral

Question 12

Arrange the interactions between pairs of electrons in order of increasing strength.

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

Question 13

A ________ geometry corresponds to a steric number of ________.

A)linear; 3
B)trigonal planar; 6
C)tetrahedral; 4
D)trigonal bipyramidal; 7
E)octahedral; 8

Question 14

Select which of the following repulsive interactions between electron pairs would be greatest.

A)
B)
C)
D)
E)All involve equal repulsive forces.

Question 15

Which statement about the shape or geometry of a molecule is not correct?

A)Physical properties of a substance are not affected by the shape of the molecules.
B)The shape of a molecule refers to the three-dimensional arrangement of the atoms in space.
C)Solubility of a substance in a solvent is affected by the shape of the molecules.
D)Taste and aroma of a substance are affected by the shape of the molecules.
E)Biological activity and chemical reactivity of a substance are affected by the shape of the molecules.

Question 16

Which electron-pair geometry corresponds to a steric number of 3?

A)linear
B)trigonal planar
C)tetrahedral
D)trigonal bipyramidal
E)octahedral

Question 17

Which bond angle is the smallest?

A)H-C-H in CH₄
B)H-C-H in C₂H₄
C)H-C-H in H₂CO
D)H-C-C in C₂H₂
E)H-C-O in H₂CO

Question 18

Which statement A-D about VSEPR theory is not correct?

A)The molecular shape or geometry can differ from the electron-pair geometry.
B)In VSEPR theory, the shape or geometry of a molecule is determined by electron-electron repulsion.
C)The steric number of a central atom is the sum of the number of bonds and lone pairs around the atom.
D)The steric number has five values from 2 to 6.
E)Statements A-D are all correct.

Question 19

Which electron-pair geometry has the largest electron-electron repulsive forces?

A)linear
B)trigonal planar
C)tetrahedral
D)trigonal bipyramidal
E)octahedral

Question 20

Predict the bond angle indicated in SF₄.

A)120 ^$\circ$
B)90 ^$\circ$
C)greater than 120 ^$\circ$
D)less than 120 ^$\circ$
E)109.5 ^$\circ$

Question 21

Which of the following molecules is T-shaped?

A)NCl₃
B)PCl₃
C)SbCl₃
D)ICl₃
E)COCl₂

Question 22

Which of the following compounds has a square pyramid geometry?

A)ICl₃
B)BrF₅
C)PCl₅
D)PH₃
E)SiF₄

Question 23

Which of the following molecules or ions has a linear molecular geometry?

A)H₂O
B)H₂S
C)ICl₃
D)I₃^-
E)SO₂

Question 24

For the series methane, ammonia, and water, the bond angle increases in the following order: H₂O < NH₃ < CH₄. This trend is due to ________

A)a decreasing effective nuclear charge.
B)a decrease in the number of lone pairs.
C)an increase in atomic radius.
D)an increase in the polarity of the molecules.
E)an increasing effective nuclear charge.

Question 25

Which of the following compounds has the same molecular shape as CCl₃H?

A)SiF₄
B)KrF₄
C)SF₄
D)C₂H₄
E)C₂H₂

Question 26

Which of the following has the largest bond angle?

A)CF₄
B)NF₃
C)F₂O
D)NF₂^-
E)NH₃

Question 27

Which of the following ions is linear?

A)SCN^-
B)NO₂^-
C)SO₃^2-
D)NH₄⁺
E)SO₂^2-

Question 28

A triatomic molecule with a bond angle close to 120^o could be ________

A)SO₂.
B)N₂O.
C)HCN.
D)CO₂.
E)BeH₂.

Question 29

Determine the molecular geometry of CF₂Cl₂.

A)linear
B)bent
C)trigonal bipyramidal
D)tetrahedral
E)trigonal pyramidal

Question 30

Which of the following compounds has a trigonal bipyramidal shape?

A)ICl₃
B)BrF₅
C)PCl₅
D)PH₃
E)SiF₄

Question 31

What is the molecular geometry of SF₄?

A)tetrahedral
B)square pyramidal
C)seesaw
D)square planar
E)T-shaped

Question 32

Which of the following is a planar molecule?

A)NH₃
B)PCl₅
C)KrF₄
D)CH₃COOH
E)SiH₄

Question 33

What is the molecular geometry of SF₄O?

A)pentagonal
B)tetrahedral
C)trigonal bipyramidal
D)trigonal planar
E)square pyramidal

Question 34

Which of the following compounds has the same geometry as SO₂?

A)H₂O
B)HCN
C)ICl₃
D)OCS
E)CO₂

Question 35

The bond angle in a trigonal planar structure is ________

A)90 ^$\circ$ .
B)180 ^$\circ$ .
C)109.5 ^$\circ$ .
D)120 ^$\circ$ .
E)105 ^$\circ$ .

Question 36

The tetrahedral bond angle is ________

A)90 ^$\circ$ .
B)180 ^$\circ$ .
C)109.5 ^$\circ$ .
D)120 ^$\circ$ .
E)105 ^$\circ$ .

Question 37

The correct H-N-H bond angle in NH₃ is ________

A)the same as the H-O-H angle in water.
B)exactly 109.5 ^$\circ$ .
C)greater than 109.5 ^$\circ$ .
D)less than 109.5 ^$\circ$ .
E)120 ^$\circ$ .

Question 38

What is the molecular geometry of the triiodide ion (I₃^-)?

A)linear
B)bent
C)tetrahedral
D)trigonal pyramidal
E)trigonal planar

Question 39

What angles are present between atoms in a molecule with octahedral geometry?

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

Question 40

Which of the following molecules or ions has a trigonal pyramid shape?

A)KrF₄
B)COCl₂
C)SeO₃^2-
D)NH₄⁺
E)O₃

Question 41

Which bond is the least polar?

A)H-C
B)H-N
C)H-O
D)H-Cl
E)H-F

Question 42

Which bond is the least polar?

A)carbon-oxygen
B)carbon-sulfur
C)carbon-nitrogen
D)carbon-fluorine
E)carbon-chlorine

Question 43

What is the molecular geometry around a central atom having four single bonds and two lone pairs (i.e., nonbonding pair)?

A)square pyramidal
B)square planar
C)trigonal bipyramidal
D)octahedral
E)seesaw

Question 44

All homonuclear diatomic molecules ________

A)have polar bonds.
B)are polar.
C)are nonpolar.
D)cannot vibrate.
E)are liquids.

Question 45

Which of the following shows the orientation of the net dipole for OCS?

A)
B)
C)
D)

Question 46

For which of the following molecules is the electron pair geometry tetrahedral and the molecular geometry pyramidal?

A)SF₄
B)SiH₄
C)BF₃
D)PH₃
E)ClF₃

Question 47

Which of the following molecules or ions is not polar?

A)O₃
B)H₂O
C)SO₂
D)I₃^-
E)S₃

Question 48

Identify the polar molecule.

A)CF₄
B)SiH₄
C)CHCl₃
D)CS₂
E)CO₂

Question 49

In the following reaction, what is the change in geometry of the silicon-containing compound?
SiH₄(g) + 2O₂(g) $\to$ H₂SiO(g) + 2H(g)

A)tetrahedral to tetrahedral
B)square planar to pyramidal
C)tetrahedral to trigonal planar
D)seesaw to tetrahedral
E)trigonal bipyramidal to bent

Question 50

What is the molecular geometry of XeF₂?

A)tetrahedral
B)bent
C)linear
D)seesaw
E)trigonal planar

Question 51

Which bond is the most polar?

A)H-C
B)H-N
C)H-O
D)H-Cl
E)H-F

Question 52

Which bond is the most polar?

A)carbon-oxygen
B)carbon-sulfur
C)carbon-nitrogen
D)carbon-silicon
E)carbon-fluorine

Question 53

What is the molecular geometry around a central atom having three single bonds and two lone pairs (i.e., nonbonding pairs)?

A)T-shaped
B)trigonal planar
C)trigonal bipyramidal
D)tetrahedral
E)seesaw

Question 54

For which of the following molecules is the electron pair geometry octahedral and the molecular geometry square planar?

A)SF₆
B)ClF₃
C)XeF₄
D)BrF₆
E)I₃^-

Question 55

What is the molecular geometry around a central atom having four single bonds and one lone pair (i.e., nonbonding pair)?

A)T-shaped
B)square planar
C)trigonal pyramidal
D)tetrahedral
E)seesaw

Question 56

Which of the following molecules or ions is not polar?

A)BF₃
B)CHCl₃
C)H₂CO
D)NH₃
E)SF₄

Question 57

What is the molecular geometry of the ClF₄^- ion?

A)square planar
B)square pyramidal
C)trigonal pyramidal
D)tetrahedral
E)seesaw

Question 58

In the following reaction, what is the change in geometry of the carbon-containing compound? COCl₂(g) + H₂O(g) $\to$ CO₂(g) + 2HCl(g)

A)tetrahedral to linear
B)trigonal planar to linear
C)T-shaped to linear
D)trigonal planar to bent
E)tetrahedral to bent

Question 59

Which of the following diagrams shows the correct orientation of the dipole in sulfur dioxide?

A)
B)
C)
D)

Question 60

In the following reaction, what is the change in geometry of the silicon-containing compound

A)tetrahedral to octahedral
B)tetrahedral to trigonal bipyramidal
C)T-shaped to octahedral
D)seesaw to octahedral
E)seesaw to square pyramidal

Question 61

Which of the following statements about bonds between two carbon atoms is/are correct? (I) Bond strength increases as more electrons are shared between the atoms.
(II) Bond strength increases as the overlap between atomic orbitals increases.
(III) Hybrid orbitals are used to describe (account for) the geometry (bond angles) around each carbon atom.

A)I
B)II
C)III
D)Only two of these are correct statements.
E)All three are correct statements.

Question 62

Which of the following molecules has a central atom that is sp³ hybridized?

A)C₂H₂
B)H₂CO
C)H₂S
D)C₂H₄
E)C₂H₂Cl₂

Question 63

Which of the following has a central atom with the same hybridization as the carbon in formaldehyde (CH₂O)?

A)SO₂
B)OCS
C)ICl₃
D)I₃^-
E)C₂H₂

Question 64

Which of the following molecules has a carbon atom that is sp³ hybridized?

A)C₂H₂
B)H₂CO
C)CH₃Cl
D)C₂H₄
E)C₂H₂Cl₂

Question 65

Which of the following compounds has the smallest dipole moment?

A)CF₂Cl₂
B)CF₃Cl
C)CF₄
D)CFCl₃
E)CHFCl₂

Question 66

Identify the hybridization of the three carbon atoms labeled in the following molecule. I II III I II III

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

Question 67

Identify the hybridization of the three carbon atoms labeled in the following molecule. I II III I II III

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

Question 68

Which statement A-D about valence bond theory is not correct?

A)Valence bond theory describes a bond as the overlap of atomic orbitals between two atoms.
B)Enhanced electron density between two positively charged nuclei attracts the nuclei together and forms the bond.
C)Hybridization of atomic orbitals is necessary to account for the molecular geometry.
D)In valence bond theory, hybridization determines the molecular shape or geometry.
E)Statements A-D are all correct.

Question 69

What is the hybridization of the bromine atom in BrF₅?

A)sp³
B)sp³d
C)sp³d ²
D)sp
E)sp²

Question 70

Which of the following compounds is the most polar?

A)NH₃
B)PH₃
C)AsH₃
D)SbH₃
E)BiH₃

Question 71

What is the hybridization of the central iodine atom in I₃^-?

A)sp
B)sp²
C)sp³d
D)sp³d ²
E)sp³

Question 72

Which of these molecules do not have a dipole moment?

A)PCl₅ and SiCl₄
B)POCl₃, SO₂Cl₂, and SO₃
C)POCl₃ and SO₂Cl₂
D)PCl₅, POCl₃, SOCl₂, SO₃, and SiCl₄
E)PCl₅, SF₆, SO₃, and SiCl₄

Question 73

What is the hybridization of the carbon atom in CS₂?

A)sp³
B)sp³d
C)sp³d ²
D)sp
E)sp²

Question 74

Which of the following has a central atom with the same hybridization as the oxygen in water?

A)SO₂
B)OCS
C)CS₂
D)NH₃
E)CO₂

Question 75

What is the hybridization of the oxygen in the H₃O⁺ ion?

A)sp²
B)sp³
C)sp³d
D)sp
E)sp³d ²

Question 76

What hybridization is needed to describe the square planar molecular geometry of KrF₄?

A)sp³
B)sp³d
C)sp³d ²
D)sp²
E)sp

Question 77

What are the hybridizations of the carbon atoms in CH₃CH₂(CO)H, in order from left to right? Note that the C O bond is a double bond.

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

Question 78

Which statement concerning benzene is not correct?

A)A second resonance structure is needed to describe benzene.
B)All the $\pi$ bonds originate from p atomic orbitals.
C)Benzene does not have a dipole moment.
D)The carbon atomic orbitals are sp² hybridized.
E)Benzene has both long and short carbon-carbon bonds.

Question 79

Which of the following diagrams shows the correct orientation of the dipole in sulfur tetrafluoride?

A)
B)
C)
D)
E)

Question 80

Which of these molecules have a dipole moment?

A)PCl₅ and SiCl₄
B)POCl₃, SO₂Cl₂, and SO₃
C)POCl₃ and SO₂Cl₂
D)PCl₅, POCl₃, SOCl₂, SO₃, and SiCl₄
E)PCl₅, SF₆, SO₃, and SiCl₄