Deck 9: The Chemical Bond

Question 1

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

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

Answer 1

D

Question 2

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

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 up

Answer 2

B

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?

A) Tetrahedral
B) Irregular tetrahedral
C) See-saw
D) Square planar

Answer 3

D

Question 4

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

A) 4
B) 8
C) 9
D) 18

Question 5

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

A) _g
B) _u
C) _g
D) _u

Question 6

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

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

Question 7

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

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_u²

Question 8

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.

A) -2√2α
B) -√2α
C) +√2α
D) +2√2α

Question 9

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

A) √2α
B) α
C) 2√2α
D) 2α

Question 10

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.

A) 326 nm
B) 526 nm
C) 263 nm
D) 201 nm