Textbook Question
Draw orbital pictures of the pi bonding in the following compounds:
f. CH3CH=NCH=C=O
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1. A Review of General Chemistry
Molecular Orbitals
3:58 minutesProblem 26a,b
Textbook Question
Indicate the kind of molecular orbital (σ, σ*, π, or π*) that results when the two atomic orbitals are combined:
a. <IMAGE>
b. <IMAGE>
Verified step by step guidance1
Step 1: Analyze the image labeled 'A'. The two atomic orbitals are overlapping end-to-end along the internuclear axis. This type of overlap typically results in the formation of a sigma (σ) molecular orbital.
Step 2: Consider the bonding interaction in 'A'. Since the lobes of the orbitals are overlapping constructively (same phase), this indicates the formation of a bonding sigma (σ) orbital.
Step 3: Analyze the image labeled 'B'. The two atomic orbitals are overlapping end-to-end along the internuclear axis, but the lobes are overlapping destructively (opposite phases). This type of interaction results in the formation of an antibonding sigma star (σ*) molecular orbital.
Step 4: Understand the concept of molecular orbitals. Sigma (σ) orbitals are formed by constructive overlap of atomic orbitals along the internuclear axis, while sigma star (σ*) orbitals are formed by destructive overlap.
Step 5: Summarize the results: 'A' corresponds to a bonding sigma (σ) orbital, and 'B' corresponds to an antibonding sigma star (σ*) orbital.
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Video duration:
3mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Molecular Orbitals
Molecular orbitals (MOs) are formed when atomic orbitals combine during the bonding process. They can be classified into bonding and antibonding orbitals. Bonding orbitals, such as σ and π, stabilize the molecule, while antibonding orbitals, like σ* and π*, destabilize it. Understanding the shapes and orientations of these orbitals is crucial for predicting molecular behavior.
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Bonding and Antibonding Orbitals
Bonding orbitals (σ and π) result from the constructive interference of atomic orbitals, leading to increased electron density between nuclei, which stabilizes the molecule. Antibonding orbitals (σ* and π*) arise from destructive interference, resulting in decreased electron density between nuclei and increased energy. Identifying whether the combination of atomic orbitals leads to bonding or antibonding orbitals is essential for understanding molecular stability.
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Orbital Symmetry and Orientation
The symmetry and orientation of atomic orbitals play a critical role in determining the type of molecular orbital formed. For example, the overlap of two p orbitals can create π or π* orbitals depending on their relative orientation. Recognizing how the shapes of orbitals interact helps predict the resulting molecular orbital type, which is key to answering the question posed.
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