(e) Which of the following statements about part (d) is correct: (i) The light excites an electron from a bonding orbital to an antibonding orbital, (ii) The light excites an electron from an antibonding orbital to a bonding orbital, or (iii) In the excited state there are more bonding electrons than antibonding electrons?

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Identify the nature of the electronic transition described in part (d) of the problem. Typically, light absorption involves the excitation of an electron from a lower energy orbital to a higher energy orbital.

Recall that bonding orbitals are lower in energy compared to antibonding orbitals. Therefore, an electron is usually excited from a bonding orbital to an antibonding orbital when light is absorbed.

Consider the implications of each statement: (i) suggests an electron is excited from a bonding to an antibonding orbital, which is a common scenario in electronic transitions.

Evaluate statement (ii), which suggests an electron is excited from an antibonding to a bonding orbital. This is less common as it would require energy release rather than absorption.

Analyze statement (iii), which implies that in the excited state, there are more bonding electrons than antibonding electrons. This would depend on the specific electronic configuration after excitation.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Molecular Orbitals

Molecular orbitals are formed from the combination of atomic orbitals when atoms bond together. They can be classified as bonding orbitals, which stabilize the molecule, and antibonding orbitals, which destabilize it. Understanding the distribution of electrons in these orbitals is crucial for predicting how molecules interact with light and undergo electronic transitions.

Electronic Transitions

Electronic transitions refer to the movement of electrons between different energy levels or orbitals within a molecule when it absorbs energy, such as light. When light is absorbed, an electron can be excited from a lower energy state (bonding orbital) to a higher energy state (antibonding orbital). This concept is fundamental in understanding how molecules absorb light and the resulting changes in their electronic structure.

Bonding vs. Antibonding Electrons

In molecular orbital theory, bonding electrons are those found in bonding orbitals, which contribute to the stability of the molecule, while antibonding electrons are located in antibonding orbitals and can weaken the bond. The ratio of bonding to antibonding electrons influences the overall stability and reactivity of the molecule. Analyzing these ratios is essential for understanding the implications of electronic transitions on molecular properties.

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Related Practice

Textbook Question

Consider the H₂⁺ ion. (c) Write the electron configuration of the ion in terms of its MOs. (d) What is the bond order in H₂⁺?

Textbook Question

Consider the H₂⁺ ion. (e) Suppose that the ion is excited by light so that an electron moves from a lower-energy to a higher-energy MO. Would you expect the excited-state H₂⁺ ion to be stable or to fall apart?

Textbook Question

Consider the H₂⁺ ion. (f) Which of the following statements about part (e) is correct: (i) The light excites an electron from a bonding orbital to an antibonding orbital, (ii) The light excites an electron from an antibonding orbital to a bonding orbital, or (iii) In the excited state there are more bonding electrons than antibonding electrons?

Textbook Question

Draw a picture that shows all three 2p orbitals on one atom and all three 2p orbitals on another atom. (a) Imagine the atoms coming close together to bond. How many σ bonds can the two sets of 2p orbitals make with each other?

Textbook Question

Draw a picture that shows all three 2p orbitals on one atom and all three 2p orbitals on another atom. (b) How many p bonds can the two sets of 2p orbitals make with each other?