Deck 11: Chemical Bonding Ii: Valence Bond and Molecular Orbital Theories

Question 1

Molecular orbitals can be formed by adding and subtracting atomic orbitals.

Answer 1

True

Question 2

Which statement is correct for the structure shown?

A)Carbon no.1 is described by sp³ hybridization.
B)The molecule contains 19 σ bonds.
C)Carbon no.2 is described by sp² hybridization.
D)The molecule contains a total of five π bonds.
E)Carbon no.7 is described by sp hybridization.

Answer 2

Carbon no.2 is described by sp² hybridization.

Question 3

For BeCl₂,the dipole moment of the molecule,hybridization on the central atom,and number of lone pairs on the central atom,respectively,are:

A)toward Be,sp²,none
B)away from Be,sp²,one
C)none,sp,none
D)toward Be,sp,one
E)none,sp³,two

Answer 3

none,sp,none

Question 4

Which combination of hybrid orbital descriptions and electron-group geometry descriptions is INCORRECT?

A)sp/linear
B)sp²/trigonal planar
C)sp³/tetrahedral
D)sp^3d/square planar
E)sp^3d2/octahedral

Question 5

Which hybrid orbitals are impossible in electrically neutral molecules containing only the elements shown?

A)sp³/Al and H
B)sp²/B and F
C)sp/C and H
D)sp²/N and O
E)sp³/O and F

Question 6

Unhybridized p orbitals must be present for electron delocalization to occur.

Question 7

Which of the pairs of molecules below have the same hybridization on the central atom? (The central atom is underlined. )

A)HOCl,ClF₃
B)H₂O,HNO
C)HCN,CO₂
D)BeH₂,NH₃
E)H₃COH,CH₂O

Question 8

According to the principles of VSEPR applied on ICl₅,which of the following is INCORRECT?

A)VSEPR formula = AX₅E
B)molecular geometry = square pyramidal
C)hybridization = sp^3d
D)electron-group geometry = octahedral
E)one lone pair and 5 bonding pairs

Question 9

Which statement regarding VB theory is INCORRECT?

A)d orbitals are not included in hybrid orbitals.
B)Hybrid orbitals use atomic orbitals from the outermost shell.
C)Sigma bonds are formed by the end-to-end overlap of orbital lobes.
D)Pi bonds are overlaps of parallel p orbitals.
E)A double bond is a sigma bond and a pi bond.

Question 10

A double bond is two sigma bonds.

Question 11

Which of the following statements concerning the carbon dioxide molecule is correct?

A)The molecule contains two lone pairs of valence electrons.
B)The molecule contains two σ bonds.
C)The molecule contains four π bonds.
D)The carbon is described by sp² hybridization.
E)Each oxygen is described by sp³ hybridization.

Question 12

Three of the molecular shapes which a sp^3d hybridized molecule can have are:

A)triangular,trigonal bipyramid,linear
B)linear,square planar,T-shaped
C)irregular tetrahedron,T-shaped,bent
D)T-shaped,linear,trigonal bipyramid
E)linear,tetragonal pyramid,octahedral

Question 13

Resonance structures and delocalized orbitals are different ways to describe the same bonding.

Question 14

Which statement is correct for the structure shown?

A)The molecule contains a total of 16 σ bonds.
B)Carbon no.1 is described by sp hybridization.
C)The molecule contains a total of four π bonds.
D)Carbon no.3 is described by sp³ hybridization.
E)The molecule contains a delocalized π bond system.

Question 15

The valence-bond method describes covalent bonding as the overlap of partially filled orbitals.

Question 16

Which statement is INCORRECT?

A)The bond length is the internuclear distance.
B)The covalent bond is a region of high electron charge density between two atoms.
C)Hybrid orbitals are combinations of atomic orbitals.
D)There are the same number of hybrid orbitals produced as the number of atomic orbitals combined.
E)An sp hybridization produces a tetrahedral molecule.

Question 17

According to principles of VSEPR theory applied on AsCl₅^2-,which of the following is INCORRECT?

A)VSEPR formula = AX₅E
B)molecular geometry = square planar
C)electron-group geometry = octahedral
D)hybridization = sp^3d2
E)one lone pair and 5 bonding pairs

Question 18

The valence-bond method provides energy information about molecules.

Question 19

The description of covalent bond formation as a region of high electronic charge density resulting from overlap of atomic orbitals between the two bonded atoms is referred to as:

A)atomic orbital theory
B)the electron-sea model
C)hybridization theory
D)valence-bond method
E)VSEPR method

Question 20

A triple bond is two sigma bonds and one pi bond.

Question 21

Which of the following carbon molecules has sp hybridization?

A)CH₄
B)C₂H₂
C)Cl₂CS
D)CH₃^-
E)CO₂

Question 22

Choose the INCORRECT statement about PCl₅.

A)There are no π bonds.
B)P has one lone pair.
C)P has sp^3d hybridization.
D)Each Cl has 3 lone pairs.
E)There are 5 σ bonds.

Question 23

Which statement regarding VB theory is INCORRECT?

A)A single bond is a sigma bond.
B)A triple bond is two sigma bonds and a pi bond.
C)A double bond requires each atom to have an unhybridized p orbital.
D)Both atoms in a triple bond have linear geometry.
E)sp³ hybridization produces tetrahedral geometry.

Question 24

Find the correct statements about the bonding in methane,CH₄.
I.The carbon s and p orbitals combine to form four equivalent sp³ orbitals
II.All C-H bonds have the same strength
III.Molecular geometry is different from electron group geometry
IV.Four C sp³ orbitals combine with the s orbitals of the hydrogens to form bonds

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

Question 25

According to VB theory,sigma bonds are:

A)always present in double bonds
B)formed only by p orbitals
C)formed only by hybrid orbitals
D)formed only by s orbitals
E)formed only by unhybridized orbitals

Question 26

A pi bond is:

A)formed from two s orbitals
B)formed from two p orbitals
C)formed from hybridized orbitals
D)formed from one s and one p orbital
E)stronger than a sigma bond

Question 27

For the molecule

A)the hybridization for C is sp³
B)the hybridization for N is sp²
C)the hybridization for O is sp³
D)N is not hybridized
E)the hybridization for C is sp²

Question 28

Choose the INCORRECT statement about AsF₆^-.

A)The hybridization is sp^3d2.
B)The molecule is octahedral.
C)There are no π bonds.
D)There is one lone pair of electrons.
E)There are six σ bonds.

Question 29

Choose the INCORRECT statement about NH₄⁺.

A)The hybridization of N is sp³.
B)The molecule is tetrahedral.
C)There is one lone pair of electrons on N.
D)There are no π bonds.
E)There are four σ bonds.

Question 30

Choose the INCORRECT statement about SnCl₂.

A)The hybridization of Sn is sp².
B)The molecule is linear.
C)There is one lone pair of electrons on Sn.
D)There are no π bonds.
E)There are two σ bonds.

Question 31

Choose the INCORRECT statement about H₃O⁺.

A)There is one π bond.
B)There are 3 σ bonds.
C)There is one lone pair of electrons on O.
D)The hybridization on O is sp³.
E)The OH bonds are O(sp³)- H(1s).

Question 32

π bonds:

A)are the only kind of bonds present in double bonds
B)have very little electron density along the internuclear axis
C)are formed by endwise overlap of p orbits
D)are formed from hybrid orbitals
E)are formed from s orbitals

Question 33

According to VB theory,a double bond that results from the sharing of four electrons consists of:

A)2 sigma bonds
B)one sigma and one pi bond
C)one sigma bond
D)two pi bonds
E)one sigma bond and one coordinate bond

Question 34

The double covalent bond between two carbon atoms in ethylene (C₂H₄):

A)is free to rotate because of delocalized electrons
B)is a sigma bond
C)consists of one sigma and one pi bond
D)has a low electron density
E)includes a "lone pair" of electrons on one of the carbons

Question 35

A σ bond:

A)can only be formed by s orbitals
B)is weaker than a pi bond
C)has high electron probability along the axis between atoms
D)cannot be formed by two p orbitals
E)is formed through side-on overlap of two atomic orbitals

Question 36

Choose the INCORRECT statement about NH₂^-

A)There are no π bonds.
B)There are two σ bonds.
C)N is sp³ hybridization.
D)The molecule is bent.
E)There is one lone pair on N.

Question 37

Which of the pairs of molecules below have the same hybridization on the central atom? (The central atom is underlined in each molecule. )

A)CO₂,CH₄
B)H₂CO,BeH₂
C)BCl₃,HNO
D)H₂O,HF
E)NH₃,HNO

Question 38

Choose the INCORRECT statement about HCN.

A)There are two π bonds.
B)There are two σ bonds.
C)N has a lone pair.
D)The molecule is bent.
E)C has sp hybridization.

Question 39

For the molecule

A)the geometry about O is linear
B)the hybridization on O is sp
C)O is not hybridized
D)both carbons are sp² hybridized
E)there are two π bonds between the two carbons

Question 40

Choose the INCORRECT statement about CO₂.

A)There are two π bonds.
B)There are two σ bonds.
C)C has one lone pair.
D)The hybridization on C is sp.
E)The molecule is linear.

Question 41

According to molecular orbital (MO)theory,which statement below is true?

A)A molecule with an even number of electrons must be diamagnetic.
B)There are as many sigma bonds as pi bonds in a molecule.
C)There are as many molecular orbitals as there are atomic orbitals.
D)There are as many bonding as antibonding electrons in a molecule.
E)All molecules contain pi bonds.

Question 42

Which of the following statements is INCORRECT?

A)A double bond is stronger than a single bond for the same atoms.
B)A double bond is less than twice as strong as a single bond for the same atoms.
C)Bonded atoms cannot rotate freely around a double bond.
D)Molecular geometry depends on the σ bond framework.
E)There are no hybridized orbitals in multiple bonds.

Question 43

According to MO theory,which is an INCORRECT statement for ?

A)The B.O.is 1/2.
B)There are no unpaired electrons.
C)The σ_1s^* orbital has one electron.
D)The molecule is paramagnetic.
E)There are 3 electrons in the molecular orbitals.

Question 44

Which of the following species is paramagnetic?

A)B₂
B)C₂
C)N₂
D)CO

Question 45

According to MO theory,all of the following have a bond order of 2 EXCEPT:

A)NO
B)CN⁺
C)C₂
D)O₂

Question 46

Choose the INCORRECT statement about NO₂⁺.

A)There is one π bond.
B)There are two σ bonds.
C)The hybridization is sp.
D)There are no lone pairs on N.
E)There are two lone pairs on each O.

Question 47

Which of the following does NOT involve any delocalized π bonds?

A)acetate ion
B)carbonate ion
C)nitric acid
D)nitrous acid
E)ozone

Question 48

According to MO theory,which is the INCORRECT statement for ?

A)The BO is 2.5.
B)There is one unpaired electron.
C)The σ_2p orbital has one electron in it.
D)The molecule is diamagnetic.
E)There are 9 electrons in the molecular orbitals.

Question 49

Which of the following involves delocalized π bonds?

A)acetylene (C₂H₂)
B)benzene (C₆H₆)
C)carbon tetrachloride (CCl₄)
D)dichlorodifluoromethane (CF₂Cl₂)
E)ethylene (C₂H₄)

Question 50

Which of the following statements concerning the relative energy levels of molecular orbitals for the O₂ molecule is INCORRECT?

A)σ_1s < σ_1s^*
B)σ_2s < σ_2p
C)π_2p < σ_2p
D)π_2p^* < σ_2p^*
E)σ_1s^* < σ_2s

Question 51

According to the molecular orbital (MO)theory,when two oxygen atoms bond together,their 2p orbitals combine to form:

A)two sigma molecular orbitals (MOs)and four pi MOs
B)two sigma MOs and two pi MOs
C)four pi MOs only
D)one sigma and one pi MO
E)a delocalized set of MO

Question 52

How would replacing one of benzene's C atoms and the H atom attached to it with an N atom (C₅H₅N)affect the delocalized electrons?

A)The molecule would not be stable.
B)The N can have delocalized electrons like C.
C)Only the five C atoms would be included in the delocalized electrons.
D)There would be no delocalized electrons but a double bond between the N and a C.
E)There would be no delocalized electrons but a double bond between the N and the C on each side of the N.

Question 53

The structure of aspirin is given below.(Note that lone pairs of electrons are not shown. )
Which set of hybrid orbitals best describes the O-C bond,labeled "a," "b," in aspirin?

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

Question 54

According to MO theory,assuming that the molecular orbitals are the same as a diatomic molecule,which is an INCORRECT statement for CN^-?

A)The BO is 2.
B)There are no unpaired electrons.
C)The σ_2p is the highest filled level.
D)The molecule is diamagnetic.
E)There are 10 electrons in the n = 2 level orbitals.

Question 55

If the HCOO^- ion is described using delocalized electrons,why can the oxygen atoms not have sp³ hybrids?

A)There must be an unhybridized p orbital to form the pi bond system.
B)The s orbital must be unhybridized to form the pi bond system.
C)There is no hybridization in systems with delocalized electrons.
D)Molecular orbital theory does not include hybridization.
E)The four lobes repel each other too strongly.

Question 56

The extra stability that a molecule gains due to electron delocalizations (the electrons being free to move throughout large parts of the molecule)is called:

A)ionization energy
B)lattice energy
C)covalent strength
D)resonance energy
E)bond energy

Question 57

According to MO theory,which is the INCORRECT statement for ?

A)The BO is 2.5.
B)There is one unpaired electron.
C)The σ_2p orbital has two electrons.
D)The molecule is paramagnetic.
E)There are 9 electrons in the molecular orbitals.

Question 58

Which of the following statements concerning molecular orbital (MO)theory is FALSE?

A)The number of MOs formed equals the number of atomic orbitals combined.
B)Any set of MOs from 2 atomic orbitals involves 1 bonding and 1 antibonding orbital.
C)Electrons normally enter the lowest energy MO available to them.
D)No more than two electrons can enter a particular MO.
E)Electrons enter MOs of identical energies in pairs before any enter singly.

Question 59

Which statement is INCORRECT about molecular orbital theory?

A)The number of molecular orbitals produced is equal to the number of atomic orbitals combined.
B)Each pair of sigma molecular orbitals is a bonding orbital and an antibonding orbital.
C)The antibonding orbital is at a lower energy than the bonding orbital.
D)The bond order (BO)is .
E)Hund's rule says that each orbital of identical energy has one electron before pairs are formed.

Question 60

The concept of an anti-bonding orbital is unique to the:

A)theory of bond hybridization
B)valence bond theory
C)molecular orbital theory
D)concept of resonance
E)electrostatic repulsion theory

Question 61

What would be the hybridization of the N in the benzene-like molecule (C₅H₅N)?

A)sp
B)sp³
C)sp^3d2
D)sp^3d
E)sp²

Question 62

Which is the correct molecular orbital diagram for O₂^- ion?

A)(_{σ 2s} ↑ _{↓ σ 2s}^* ↑ ↓ σ_2p ↑ ↓ π_2p ↑ ↓ π_2p^* ↑ ↓,↑)
B)(_{σ 2s} ↑ _{↓ σ 2s}^* ↑ ↓ σ_2p ↑ ↓ π_2p ↑ ↓,↑ ↓ π_2p^* ↑ ↑,↑)
C)(_{σ 2s} ↑ _{↓ σ 2s}^* ↑ ↓ σ_2p ↑ π_2p ↑ ↓,↑ ↓ π_2p^* ↑ ↓)
D)(_{σ 2s} ↑ _{↓ σ 2ss}^* ↑ ↓ σ_2p ↑ ↓ π_2p ↑ ↓,↑ ↓ π_2p^* ↑))
E)(_{σ 2s} ↑ _{↓ σ 2ss}^* ↑ σ_2p ↑ ↓ π_2p ↑ ↓,↑ ↓,↑ ↓ π_2p^* ↑)

Question 63

If the wave functions describing the 2s and two of the 2p orbitals are combined,the identical orbitals derived form bond angles of ________.

A)90°
B)120°
C)180°
D)109.5°
E)360°

Question 64

How many σ bonds and how many π bonds are present in the carbonic acid molecule,H₂CO₃?

A)2σ/4π
B)3σ/3π
C)4σ/2π
D)5σ/1π
E)6σ/0π

Question 65

What is the hybridization of the Xe atom in XeF₂?

A)sp³d
B)sp
C)sp³
D)sp²

Question 66

The octahedral hybrid configuration is composed of which orbital combination?

A)sp^3d2
B)sp^2d3
C)spd²
D)sp^3d
E)sp³

Question 67

The structure of aspirin is given below.(Note that lone pairs are not shown. )
What is the O-C-C bond angle,"x," in aspirin?

A)~120°
B)~109°
C)~90°
D)~180°

Question 68

Which is the correct molecular orbital diagram for carbon monoxide?

A)(_{σ 2s} ↑ _{↓ σ 2s}^* ↑ _↓ π_2p ↑ _↓,↑ _↓ σ_2p ↑ _↓)
B)(_{σ 2s} ↑ _{↓ σ 2s}^* ↑ _↓ π_2p ↑ _↓,↑ _↓ σ_2p ↑ π_2p* ↑)
C)(_{σ 2s} ↑ _{↓ σ 2s}^* ↑ _↓ π_2p ↑ _↓,σ_2p ↑ _↓ π_2p* ↑ _↓)
D)(_{σ 2s} ↑ _{↓ σ 2s}^* ↑ _↓ π_2p ↑,↑,σ_2p ↑ _↓ π_2p* ↑ _↓)
E)(_{σ 2s} ↑ _{↓ σ 2s}^* ↑ _↓ π_2pp ↑ _↓,↑ _↓ π_2p* ↑ _↓)

Question 69

One resonance structure of N₂O is
The hybridized atomic orbitals of the central nitrogen atom which are consistent with this structure are ________.

A)four sp³ orbitals
B)three sp² orbitals and a p orbital
C)two sp² orbitals and two sp orbitals
D)two sp orbitals and two p orbitals
E)one sp orbital and two p orbitals

Question 70

The geometry of sp² hybridized orbitals is ________.

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

Question 71

According to the valence bond theory,in the ion NH₄⁺,nitrogen is using which orbitals for bonding?

A)sp³
B)p
C)sp^2d
D)sp
E)s

Question 72

The hybridization on Xe in XeF₄ is ________.

A)not hybridized
B)sp³
C)sp^3d
D)sp^3d2
E)sp^2d

Question 73

The HCOO^- ion can be described by using delocalized electrons.What is the hybridization of the C atom?

A)sp
B)sp³
C)sp^2d
D)sp^3d
E)sp²

Question 74

How many π-electrons are there in S₂O where S is the central atom?

A)4
B)2
C)6
D)0

Question 75

What is the hybridization of the S atom in SF₄?

A)sp³d
B)sp³
C)sp³d²
D)spd²

Question 76

The hybridization of N in NO₂^- is ________.

A)sp
B)sp²
C)sp^3d
D)sp³
E)sp^3d2

Question 77

For XeF₄,what are the dipole moment orientation,hybridization on the central atom,and the number of lone pairs,respectively,on the central atom?

A)none,sp^3d2,two
B)none,sp³,none
C)away from one pair,sp^3d,one
D)toward one pair,sp^3d,one
E)toward Xe,sp^3d2,one

Question 78

What are the ideal bond angles for H₂O?

A)120°
B)109.5°
C)90°
D)180°
E)75°

Question 79

How many σ- and π-bonds,respectively,are there in phenylisothiocyanate,C₆H₅NCS? Ignore the C-H bonds in your counting.

A)9 and 5
B)8 and 4
C)5 and 5
D)9 and 2

Question 80

The three molecular shapes an sp³ hybridized molecule can have are ________.

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