(b) When applying the VSEPR model, we count a double or triple bond as a single electron domain. Why is this justified?

Verified step by step guidance

Step 1: Understand the VSEPR model, which stands for Valence Shell Electron Pair Repulsion theory. It is used to predict the geometry of molecules based on the repulsion between electron pairs in the valence shell of the central atom.

Step 2: Recognize that in the VSEPR model, electron domains are regions where electrons are likely to be found. These include lone pairs, single bonds, double bonds, and triple bonds.

Step 3: Note that a double or triple bond is considered a single electron domain because the electrons in these bonds are shared between the same two atoms, and thus, they occupy the same region of space.

Step 4: Consider that the VSEPR model focuses on the spatial arrangement of electron domains around the central atom, and since double and triple bonds do not create additional regions of electron density, they are counted as one domain.

Step 5: Understand that this simplification helps in predicting the molecular geometry more easily, as it reduces the complexity of counting multiple electron pairs within the same bond.

Key Concepts

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

VSEPR Model

The Valence Shell Electron Pair Repulsion (VSEPR) model is a theory used to predict the geometry of molecular structures based on the repulsion between electron pairs in the valence shell of central atoms. It posits that electron domains, which include lone pairs, single bonds, double bonds, and triple bonds, will arrange themselves to minimize repulsion, leading to specific molecular shapes.

Electron Domains

In the context of VSEPR, an electron domain refers to a region around a central atom where electrons are likely to be found. This includes lone pairs and bonds (single, double, or triple). Counting double and triple bonds as a single electron domain simplifies the model, as it reflects the overall spatial arrangement and repulsion effects without overcomplicating the geometry.

Bonding and Repulsion

The concept of bonding and repulsion is fundamental in understanding molecular geometry. Bonds, whether single, double, or triple, consist of shared electron pairs that create attractive forces between atoms. However, the presence of multiple bonds does not significantly increase the spatial requirements compared to a single bond, allowing them to be treated as one domain in the VSEPR model, which focuses on minimizing repulsive interactions.

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Valence Shell Electron Pair Repulsion Theory

Related Practice

Textbook Question

Consider the molecular orbitals of the P2 molecule. Assume that the MOs of diatomics from the third row of the periodic table are analogous to those from the second row. (c) For the P2 molecule, how many electrons occupy the MO in the figure?

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Textbook Question

The iodine bromide molecule, IBr, is an interhalogen compound. Assume that the molecular orbitals of IBr are analogous to the homonuclear diatomic molecule F2. (a) Which valence atomic orbitals of I and of Br are used to construct the MOs of IBr?

Textbook Question

The iodine bromide molecule, IBr, is an interhalogen compound. Assume that the molecular orbitals of IBr are analogous to the homonuclear diatomic molecule F2. (c) One of the valence MOs of IBr is sketched here. Why are the atomic orbital contributions to this MO different in size?

Textbook Question

An AB2 molecule is described as having a tetrahedral geometry. (a) How many nonbonding domains are on atom A?

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Textbook Question

An AB2 molecule is described as having a tetrahedral geometry. (b) Based on the information given, which of the following is the molecular geometry of the molecule: (i) linear, (ii) bent, (iii) trigonal planar, or (iv) tetrahedral?

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Textbook Question

Consider the following XF₄ ions: PF₄^-, BrF₄^-, ClF₄⁺, and AlF₄^-. (a) Which of the ions have more than an octet of electrons around the central atom?