Question 1

Using the Hückel method, the energies of the  orbitals of the allyl radical, C3H4, are calculated to be
,α and α±√2 β
Calculate the energy of the delocalised  system relative to the energy of electrons in isolated p orbitals.

Accepted Answer

A)   -2√2α
B)   -√2α
C)   +√2α
D)   +2√2αE) B) and C)
F) None of the above

Question 2

Hückel theory predicts that the energies of the  orbitals of 1,3-butadiene, C4H6, are
E1=α+1.62α
E2=α+1.62α
E3=α-1.62α
E4=α-1.62α
Predict the wavelength of the lowest energy transition in the electronic spectrum of butadiene, given that  = -3.8 eV.

Accepted Answer

A)   326 nm
B)   526 nm
C)   263 nm
D)   201 nmE) C) and D)
F) All of the above C

Question 3

The bonding within xenon tetrafluoride, XeF4, is best described, using valence-bond and valence-shell electron-pair repulsion theory, as resulting from formation of sp3d2 hybrid orbitals on the xenon atom, four of which form  bonds to fluorine atoms. Which of the following structures is consistent with this model?

Accepted Answer

A)   Tetrahedral
B)   Irregular tetrahedral
C)   See-saw
D)   Square planarE) None of the above
F) A) and C)

Question 4

What is the separation between the highest occupied and lowest unoccupied molecular orbitals of benzene?

Accepted Answer

A)   √2α
B)   α
C)   2√2α
D)   2αE) None of the above
F) All of the above D

Question 5

Which of the following spin functions represents a valid spin wavefunction for two paired electrons?

Accepted Answer

A)   (1) (2) 
B)   (1) (2) 
C)   (1) (2)  +(1) (2) 
D)   (1) (2)  -(1) (2) E) A) and B)
F) A) and C)

Question 6

Which of the following describes the electronic configuration of the electronic ground state of the F2 molecule?

Accepted Answer

A)   1g21u22g21u41g4
B)   1g21u21u42g22u21g2
C)   1g21u21u42g21g4
D)   1g21u21u42g21g22u2E) B) and C)
F) A) and D) A

Question 7

Which of the following represents the best description of the bonding in an octahedral molecule such as sulfur hexafluoride, SF6, using valence-bond theory.

Accepted Answer

A)   Six spd4 hybrid orbitals formed by the central sulfur atom, each making up a  bond.
B)   Six equivalent sp3d2 hybrid orbitals formed by the central sulfur atom, each making up a  bond.
C)   Six p3d3 hybrid orbitals formed by the central sulfur atom, each making up a  bond.
D)   Seven equivalent pd6 hybrid orbitals formed by the central sulfur atom, with six making upE) B) and D)
F) B) and C)

Question 8

Use molecular orbital theory to determine whether the Ne2+ ion is likely to be bound, and if so, to predict its bond order.

Accepted Answer

A)   Not bound, bond order b = 0
B)   Bound, bond order b = ½
C)   Bound, bond order b = 1
D)   Bound, bond order b = 2E) B) and D)
F) B) and C)

Question 9

How many molecular orbitals can be built from the valence atomic orbitals of molecular bromine, Br2?

Accepted Answer

A)   4
B)   8
C)   9
D)   18E) None of the above
F) C) and D)

Question 10

What is the symmetry of the bonding molecular orbital formed by a linear combination of the px  or py atomic orbitals in a homonuclear diatomic molecule?

Accepted Answer

A)   g
B)   u
C)   g
D)   uE) A) and B)
F) B) and D)

Exam 9: The Chemical Bond

Using the Hückel method, the energies of the  orbitals of the allyl radical, C₃H₄, are calculated to be ,α and α±√2 β Calculate the energy of the delocalised  system relative to the energy of electrons in isolated p orbitals.

Correct Answer
verified

Hückel theory predicts that the energies of the  orbitals of 1,3-butadiene, C₄H₆, are E₁=α+1.62α E₂=α+1.62α E₃=α-1.62α E₄=α-1.62α Predict the wavelength of the lowest energy transition in the electronic spectrum of butadiene, given that  = -3.8 eV.

Correct Answer
verified
C

Correct Answer
verified

What is the separation between the highest occupied and lowest unoccupied molecular orbitals of benzene?

Correct Answer
verified
D

Which of the following spin functions represents a valid spin wavefunction for two paired electrons?

Correct Answer
verified

Which of the following describes the electronic configuration of the electronic ground state of the F₂ molecule?

Correct Answer
verified
A

Which of the following represents the best description of the bonding in an octahedral molecule such as sulfur hexafluoride, SF₆, using valence-bond theory.

Correct Answer
verified

Use molecular orbital theory to determine whether the Ne₂⁺ ion is likely to be bound, and if so, to predict its bond order.

Correct Answer
verified

How many molecular orbitals can be built from the valence atomic orbitals of molecular bromine, Br₂?

Correct Answer
verified

What is the symmetry of the bonding molecular orbital formed by a linear combination of the p_x or p_yatomic orbitals in a homonuclear diatomic molecule?

Correct Answer
verified

Exam 9: The Chemical Bond

Using the Hückel method, the energies of the  orbitals of the allyl radical, C3H4, are calculated to be ,α and α±√2 β Calculate the energy of the delocalised  system relative to the energy of electrons in isolated p orbitals.

Correct AnswerverifiedShow Answer

Hückel theory predicts that the energies of the  orbitals of 1,3-butadiene, C4H6, are E1=α+1.62α E2=α+1.62α E3=α-1.62α E4=α-1.62α Predict the wavelength of the lowest energy transition in the electronic spectrum of butadiene, given that  = -3.8 eV.

Correct AnswerverifiedC

Correct AnswerverifiedShow Answer

What is the separation between the highest occupied and lowest unoccupied molecular orbitals of benzene?

Correct AnswerverifiedD

Which of the following spin functions represents a valid spin wavefunction for two paired electrons?

Correct AnswerverifiedShow Answer

Which of the following describes the electronic configuration of the electronic ground state of the F2 molecule?

Correct AnswerverifiedA

Which of the following represents the best description of the bonding in an octahedral molecule such as sulfur hexafluoride, SF6, using valence-bond theory.

Correct AnswerverifiedShow Answer

Use molecular orbital theory to determine whether the Ne2+ ion is likely to be bound, and if so, to predict its bond order.

Correct AnswerverifiedShow Answer

How many molecular orbitals can be built from the valence atomic orbitals of molecular bromine, Br2?

Correct AnswerverifiedShow Answer

What is the symmetry of the bonding molecular orbital formed by a linear combination of the px or py atomic orbitals in a homonuclear diatomic molecule?

Correct AnswerverifiedShow Answer

Using the Hückel method, the energies of the  orbitals of the allyl radical, C₃H₄, are calculated to be ,α and α±√2 β Calculate the energy of the delocalised  system relative to the energy of electrons in isolated p orbitals.

Correct Answer
verified

Hückel theory predicts that the energies of the  orbitals of 1,3-butadiene, C₄H₆, are E₁=α+1.62α E₂=α+1.62α E₃=α-1.62α E₄=α-1.62α Predict the wavelength of the lowest energy transition in the electronic spectrum of butadiene, given that  = -3.8 eV.

Correct Answer
verified
C

Correct Answer
verified

Correct Answer
verified
D

Correct Answer
verified

Which of the following describes the electronic configuration of the electronic ground state of the F₂ molecule?

Correct Answer
verified
A

Which of the following represents the best description of the bonding in an octahedral molecule such as sulfur hexafluoride, SF₆, using valence-bond theory.

Correct Answer
verified

Use molecular orbital theory to determine whether the Ne₂⁺ ion is likely to be bound, and if so, to predict its bond order.

Correct Answer
verified

How many molecular orbitals can be built from the valence atomic orbitals of molecular bromine, Br₂?

Correct Answer
verified

What is the symmetry of the bonding molecular orbital formed by a linear combination of the p_x or p_yatomic orbitals in a homonuclear diatomic molecule?

Correct Answer
verified