Question 1

In H₂⁺, how many nodes does the 1s_u* orbital have along the internuclear axis?

Accepted Answer

The 1s_u* orbital in H₂⁺ is an antibonding molecular orbital, which typically has one node along the internuclear axis.

Question 2

If you excited the electron in H₂⁺ from the 1s_g state to the 1s_u* what would expect to happen to the molecule?

Accepted Answer

Exciting the electron from the 1s_g bonding state to the 1s_u* antibonding state weakens the bond, leading to dissociation into an H atom and H⁺ ion.

Question 3

At large internuclear distances the 1p_g orbital in H₂⁺ resembles

Accepted Answer

D

Question 4

Which of the following describe the 1s_u* orbital in H₂⁺?

Accepted Answer

The 1s_u* orbital in H₂⁺ is an antibonding orbital (A), has a node along the internuclear axis (B), and is odd with respect to inversion (C).

Question 5

Which will have a longer bond length, H₂ or He₂⁺?

Accepted Answer

He₂⁺ has a longer bond length because it has fewer electrons in the bonding molecular orbital compared to H₂, resulting in a weaker bond and thus a longer bond length.

Question 6

Which of the following has the highest bond order O₂, O₂⁺, N₂, N₂⁺?

Accepted Answer

N₂ has the highest bond order of 3, due to its triple bond, compared to the other molecules listed.

Question 7

What is the bond order in Cl₂?

Accepted Answer

The bond order of Cl2 is 1 because it forms a single covalent bond between the two chlorine atoms.

Question 8

To be paramagnetic a molecule must have

Accepted Answer

A molecule is paramagnetic if it has at least one unpaired electron, which causes it to be attracted to a magnetic field.

Question 9

If you remove one of the electrons from N₂ what will happen to its bond length?

Accepted Answer

Removing an electron from N₂ results in a positive ion (N₂⁺), which has a weaker bond due to the removal of an electron from a bonding molecular orbital, leading to an increase in bond length.

Question 10

In the correlation diagram for HF the molecular orbitals are formed by mixing the 1s on the hydrogen with a 2p orbital in fluorine because

Accepted Answer

The answer of In the correlation diagram for HF the...

Question 11

In photoelectron spectroscopy if an electron is removed from a bonding orbital the vibrational fine structure will exhibit a

Accepted Answer

Removing an electron from a bonding orbital weakens the bond, leading to a lower vibrational frequency compared to the parent molecule.

Question 12

The orbital energy of core electrons in a molecule are

Accepted Answer

Core electrons are not significantly affected by bonding and thus their energy levels remain nearly identical to those in the unbonded atom.

Question 13

In a photoelectron spectrum of N₂, you would expect the electrons coming off with the highest kinetic energy to be associated with which MO?

Accepted Answer

The answer of In a photoelectron spectrum of N₂, you...

Question 14

Why does the VB model predict there will be no bonding in BeH₂?

Accepted Answer

In the valence bond (VB) model, bonding requires unpaired electrons to form bonds. Beryllium (Be) in its ground state has no unpaired electrons, which means it cannot form bonds with hydrogen (H) without hybridization or excitation.

Question 15

A simple VB wavefunction for Na₂ would be

Accepted Answer

The correct wavefunction for Na2 involves the bonding of the outermost electrons, which are in the 3s orbitals for sodium. The symmetric combination (Yg) of these orbitals is represented by option D.

Question 16

What would the VB model predict for the valency of C without "promotion" or "hybridization"?

Accepted Answer

The valency of carbon without promotion or hybridization is 2, as it would only use its two unpaired electrons in the 2p orbitals for bonding.

Question 17

What are the VB wavefunctions for the bonds in NH₃?

Accepted Answer

The answer of What are the VB wavefunctions for the...

Question 18

What do you predict for the hybridization of the central atom in CCl₃?

Accepted Answer

The central carbon atom in CCl₃ has four electron groups around it (three C-Cl bonds and one lone pair). According to the VSEPR theory, the electron groups will adopt a tetrahedral arrangement to minimize repulsion. This requires the carbon atom to be sp³ hybridized.

Question 19

In the molecule, H-CºN, the VB model would describe the sigma bond between the C and the N as a combination of

Accepted Answer

The sigma bond between carbon and nitrogen in H-CºN is formed by the overlap of an sp hybridized orbital on carbon and a 2p orbital on nitrogen.

Question 20

In the molecule, H-CºN, the VB model would predict how many s and p bonds?

Accepted Answer

The answer of In the molecule, H-CºN, the VB model...

Quiz 6: Quantum Mechanics and Molecular Structure

In H2+, how many nodes does the 1su* orbital have along the internuclear axis?

If you excited the electron in H2+ from the 1sg state to the 1su* what would expect to happen to the molecule?

At large internuclear distances the 1pg orbital in H2+ resembles

Which of the following describe the 1su* orbital in H2+?

Which will have a longer bond length, H2 or He2+?

Which of the following has the highest bond order O2, O2+, N2, N2+?

What is the bond order in Cl2?