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?

Verified step by step guidance

1. Step 1: Understand the concept of bonding and antibonding orbitals. Bonding orbitals are formed by the constructive interference of atomic orbitals, and electrons in these orbitals help to hold the two atoms together, thus creating a bond. Antibonding orbitals, on the other hand, are formed by the destructive interference of atomic orbitals, and electrons in these orbitals can destabilize the bond between atoms.
2. Step 2: Recognize that the H2+ ion is in its ground state before the light is shone on it. In the ground state, electrons occupy the lowest energy levels available, which are the bonding orbitals.
3. Step 3: Understand that when light is shone on the H2+ ion, it provides energy that can excite an electron. This means that the electron can absorb the energy from the light and move to a higher energy level.
4. Step 4: Realize that the higher energy levels are the antibonding orbitals. Therefore, the light excites an electron from a bonding orbital to an antibonding orbital.
5. Step 5: Understand that in the excited state, there are not more bonding electrons than antibonding electrons. The excitation of the electron has moved it from a bonding to an antibonding orbital, so the number of bonding electrons has decreased.

Key Concepts

Molecular Orbitals

Molecular orbitals are formed by the combination of atomic orbitals when atoms bond together. In diatomic molecules like H2+, electrons occupy these orbitals, which can be classified as bonding (lower energy, stabilizing) or antibonding (higher energy, destabilizing). Understanding the distribution of electrons in these orbitals is crucial for predicting the behavior of molecules when they absorb light.

Excitation of Electrons

When a molecule absorbs light, it can provide enough energy to excite an electron from a lower energy state (such as a bonding orbital) to a higher energy state (such as an antibonding orbital). This process alters the electron configuration of the molecule, which can affect its stability and reactivity. The specific transitions depend on the energy levels of the molecular orbitals involved.

Bonding vs. Antibonding Electrons

In a molecular ion like H2+, the balance between bonding and antibonding electrons determines the stability of the molecule. Bonding electrons contribute to the attraction between nuclei, while antibonding electrons can weaken this attraction. Analyzing the number of electrons in each type of orbital is essential for understanding the overall bond order and stability of the ion in its excited state.