Question 1

All of the following statements concerning molecular orbital (MO)theory are correct EXCEPT
A) the Pauli exclusion principle is obeyed.
B) Hund's rule is obeyed.
C) electrons are assigned to orbitals of successively higher energy.
D) a bonding molecular orbital is lower in energy than its parent atomic orbitals.
E) the combination of two atomic orbitals creates only one molecular orbital.

Accepted Answer

The combination of two atomic orbitals can create two molecular orbitals: one bonding and one antibonding.

Question 2

A molecular orbital that decreases the electron density between two nuclei is said to be ____.
A) hybridized
B) bonding
C) antibonding
D) pi-bonding
E) nonpolar

Accepted Answer

Antibonding molecular orbitals have nodes, or regions of zero electron density, between the nuclei. This means that they do not contribute to bonding and can in fact weaken existing bonds.

Question 3

Which of the labeled carbon atoms (C₁-C₄)is/are sp hybridized? A) C₁ B) C₁ and C₂ C) C₃ D) C₂ and C₄ E) C₁ and C₃

Accepted Answer

The answer of Which of the labeled carbon atoms (C₁-C₄)is/are...

Question 4

Refer to Diagram 9-1.According to molecular orbital theory,which of the following species will be paramagnetic? A) Li₂ B) C₂ C) C₂- D) F₂ E) O₂2+

Accepted Answer

According to molecular orbital theory, if a species has unpaired electrons in its molecular orbitals, it will be paramagnetic. In species A, B, D, and E, all electrons are paired, so they will be diamagnetic. In species C, there is an extra electron placed in the antibonding π* orbital, which is not paired, making it paramagnetic.

Question 5

Refer to Diagram 9-1.Consider the molecules B₂,C₂,N₂ and F₂.Which two molecules have the same bond order? A) B₂ and C₂ B) B₂ and F₂ C) C₂ and N₂ D) C₂ and F₂ E) N₂ and F₂

Accepted Answer

The answer of Refer to Diagram 9-1.Consider the molecules B₂,C₂,N₂...

Question 6

Atomic orbitals combine most effectively to form molecular orbitals when
A) electrons in the orbitals have no spins.
B) electrons in the orbitals have the same spin.
C) the atoms have an equal number of valence electrons.
D) the atomic orbitals have similar energies.
E) only d-orbitals are used in bonding.

Accepted Answer

Atomic orbitals that have similar energies combine most effectively because the energy levels of the atomic orbitals determine the potential energy of the electrons and their likelihood of interacting to form a stable molecule. If the energy levels are too different, the electrons will not be able to form stable bonds.

Question 7

Refer to Diagram 9-1.According to molecular orbital theory,which of the following species will have only one unpaired electron? A) C₂ B) Ne₂2+ C) O₂2- D) N2 E) O₂+

Accepted Answer

The species O₂+ (O2+) will have only one unpaired electron according to molecular orbital theory. This is because when you remove an electron from the molecular oxygen (O2), which normally has two unpaired electrons in its π*2p molecular orbitals, it results in a species (O2+) with only one unpaired electron.

Question 8

Refer to Diagram 9-1.According to molecular orbital theory,which of the following species will have the lowest bond order? A) He₂+ B) H₂ C) C₂+ D) F₂2+ E) F₂

Accepted Answer

The bond order can be calculated using the formula: Bond Order = (Number of bonding electrons - Number of antibonding electrons) / 2. The species with the lowest bond order will have the highest number of antibonding electrons relative to bonding electrons. He₂+ has no electrons in bonding molecular orbitals and thus has the lowest bond order, effectively making it a species with no bond (bond order = 0).

Question 9

What is the hybridization of oxygen atom O? A) sp B) sp² C) sp³ D) sp⁴ E) none

Accepted Answer

Oxygen in its ground state has two unpaired electrons in the p orbital. In hybridization theory, the s and p orbitals combine to form hybrid orbitals. One s and one p combine to make sp hybrid orbitals, which give two hybrid orbitals with one unpaired electron each. The remaining two p orbitals combine to make two more hybrid orbitals, each with two unpaired electrons. So, the hybridization of oxygen is sp², where "S" represents a single hybrid orbital, "P" represents a doubly hybridized orbital, "1U1" means one unpaired electron in the hybrid orbital, and "2" means two unpaired electrons in the hybrid orbital.

Question 10

Refer to Diagram 9-1.According to molecular orbital theory,what is the bond order of Ne₂2+? A) 0 B) 0.5 C) 1 D) 1.5 E) 2

Accepted Answer

The bond order of Ne₂2+ is 0. This is because the number of bonding electrons (6) is equal to the number of antibonding electrons (6).

Question 11

Ammonia reacts with oxygen and water to produce nitric acid.What change in hybridization of the nitrogen atom occurs in this reaction? A) sp³ to sp² B) sp³ to sp C) sp² to sp³ D) sp² to sp E) no change

Accepted Answer

In ammonia (NH3), nitrogen is sp³ hybridized. In nitric acid (HNO3), the nitrogen is sp² hybridized due to the formation of a double bond with oxygen.

Question 12

Which of the underlined atoms (C₁,C₂,N,and O)are sp² hybridized? A) N and O B) C1 and N C) C1 and O D) C2 and N E) C1 and C2

Accepted Answer

The answer of Which of the underlined atoms (C₁,C₂,N,and O)are...

Question 13

For which of the following compounds is it possible for cis and trans isomers to exist? 
A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3

Accepted Answer

The answer of For which of the following compounds is...

Question 14

Upon combustion,ethene (C₂H₄)is converted to carbon dioxide and water.What change occurs in the hybridization of carbon atoms in this reaction? A) sp to sp² B) sp² to sp³ C) sp³ to sp D) sp² to sp E) sp³ to sp²

Accepted Answer

The hybridization of carbon atoms in ethene is sp2. During the combustion, ethene is oxidized to carbon dioxide, which has sp hybridization. The hybridization of water is sp3. Therefore, the hybridization of carbon atoms in ethene changes from sp2 to sp in carbon dioxide. As a result, the correct choice is D, "sp2 to sp".

Question 15

Nitric acid,HNO₃,dissociates in water to form nitrate ions and hydronium ions.What change in hybridization of the nitrogen atom occurs in this dissociation? A) sp² to sp³ B) sp² to sp C) sp³ to sp D) sp to sp³ E) no change

Accepted Answer

In nitric acid, the nitrogen atom is already sp² hybridized, and this hybridization does not change upon dissociation into nitrate ions and hydronium ions.

Question 16

Refer to Diagram 9-1.According to molecular orbital theory,which of the following lists ranks the fluorine species in terms of increasing bond order? A) F₂²⁺ < F₂^2- < F₂ B) F₂^2- < F₂ < F₂²⁺ C) F₂ < F₂²⁺ < F₂^2- D) F₂ < F₂^2- < F₂²⁺ E) F₂²⁺ < F₂ < F₂^2-

Accepted Answer

The answer of Refer to Diagram 9-1.According to molecular orbital...

Question 17

Refer to Diagram 9-1.According to molecular orbital theory,which of the following species will have the highest bond order? A) H₂- B) Li₂ C) C₂+ D) N₂ E) H₂

Accepted Answer

The bond order in molecular orbital theory is calculated as (bonding electrons - antibonding electrons)/2. The species with the highest bond order will have the greatest difference between the number of bonding and antibonding electrons, indicating a stronger bond. Without the specific details from Diagram 9-1, we rely on general knowledge that N2 (which D seems to represent if we correct the notation to N2) has a triple bond in its diatomic form, indicating a high bond order, typically higher than that of other diatomic molecules formed by elements in similar periods.

Question 18

Refer to Diagram 9-1.According to molecular orbital theory,which of the following species will be diamagnetic? A) O₂ B) C₂+ C) F₂- D) H₂ E) Li₂+

Accepted Answer

According to molecular orbital theory, if all the electrons in a species are paired, then the species is diamagnetic. In Option D, the H2 molecule has only two electrons, which are paired in the σ1s molecular orbital, making it diamagnetic. Options A, B, C, and E all have unpaired electrons, making them paramagnetic.

Question 19

Which of the following hybridized atoms is impossible to form? A) An sp hybridized nitrogen atom B) An sp² hybridized oxygen atom C) An sp³ hybridized boron atom D) An sp³ hybridized phosphorus atom E) An sp³ hybridized hydrogen atom

Accepted Answer

Hydrogen has only one electron and can form a maximum of one covalent bond, making it impossible to achieve hybridization states that require more than one electron to participate, such as sp^3.

Question 20

Refer to Diagram 9-1.According to molecular orbital theory,what is the bond order of O₂-? A) 1 B) 1.5 C) 2 D) 2.5 E) 3

Accepted Answer

The answer of Refer to Diagram 9-1.According to molecular orbital...

Quiz 10: Bonding and Molecular Structure Orbital Hybridization and Molecular Orbitals

All of the following statements concerning molecular orbital (MO) theory are correct EXCEPT

A molecular orbital that decreases the electron density between two nuclei is said to be ____.

Which of the labeled carbon atoms (C₁-C₄) is/are sp hybridized?

Refer to Diagram 9-1.According to molecular orbital theory,which of the following species will be paramagnetic?

Refer to Diagram 9-1.Consider the molecules B₂,C₂,N₂ and F₂.Which two molecules have the same bond order?

Atomic orbitals combine most effectively to form molecular orbitals when

Refer to Diagram 9-1.According to molecular orbital theory,which of the following species will have only one unpaired electron?

Refer to Diagram 9-1.According to molecular orbital theory,which of the following species will have the lowest bond order?

What is the hybridization of oxygen atom O?

Refer to Diagram 9-1.According to molecular orbital theory,what is the bond order of Ne₂2+?

Ammonia reacts with oxygen and water to produce nitric acid.What change in hybridization of the nitrogen atom occurs in this reaction?

Which of the underlined atoms (C₁,C₂,N,and O) are sp² hybridized?

For which of the following compounds is it possible for cis and trans isomers to exist?

Upon combustion,ethene (C₂H₄) is converted to carbon dioxide and water.What change occurs in the hybridization of carbon atoms in this reaction?

Nitric acid,HNO₃,dissociates in water to form nitrate ions and hydronium ions.What change in hybridization of the nitrogen atom occurs in this dissociation?

Refer to Diagram 9-1.According to molecular orbital theory,which of the following lists ranks the fluorine species in terms of increasing bond order?

Refer to Diagram 9-1.According to molecular orbital theory,which of the following species will have the highest bond order?

Refer to Diagram 9-1.According to molecular orbital theory,which of the following species will be diamagnetic?

Which of the following hybridized atoms is impossible to form?

Refer to Diagram 9-1.According to molecular orbital theory,what is the bond order of O₂-?