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Ch.11 - Chemical Bonding II: Molecular Shapes, VSEPR & MO Theory
Tro - Chemistry: A Molecular Approach 6th Edition
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217Not the one you use?Change textbook
All textbooksTro 6th EditionCh.11 - Chemical Bonding II: Molecular Shapes, VSEPR & MO TheoryProblem 9
Chapter 11, Problem 9

For each compound, draw the Lewis structure, determine the geometry using VSEPR theory, determine whether the molecule is polar, identify the hybridization of all interior atoms, and make a sketch of the molecule according to valence bond theory, showing orbital overlap. a. IF5 b. CH2CHCH3 c. CH3SH

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For each compound, start by drawing the Lewis structure: a. For IF5, count the valence electrons (Iodine has 7, each Fluorine has 7, total 42 electrons). Arrange them to satisfy the octet rule for each atom. b. For CH2CHCH3, identify the connectivity (CH2=CH-CH3) and count the valence electrons (Carbon has 4, Hydrogen has 1). c. For CH3SH, count the valence electrons (Carbon has 4, Hydrogen has 1, Sulfur has 6).
Determine the geometry using VSEPR theory: a. For IF5, with 5 bonding pairs and 1 lone pair on Iodine, the geometry is square pyramidal. b. For CH2CHCH3, the geometry around each carbon is determined by the number of bonds: sp2 hybridized carbons are trigonal planar, sp3 hybridized carbons are tetrahedral. c. For CH3SH, the geometry around the sulfur is bent due to the lone pairs.
Assess the polarity of each molecule: a. IF5 is polar due to the asymmetrical distribution of electrons and the presence of a lone pair. b. CH2CHCH3 is nonpolar overall, but the C=C bond is polar. c. CH3SH is polar due to the S-H bond and the bent shape.
Identify the hybridization of all interior atoms: a. In IF5, Iodine is sp3d2 hybridized. b. In CH2CHCH3, the first two carbons are sp2 hybridized, and the last carbon is sp3 hybridized. c. In CH3SH, the carbon is sp3 hybridized, and the sulfur is also sp3 hybridized.
Sketch the molecule according to valence bond theory, showing orbital overlap: a. For IF5, show the overlap of sp3d2 hybrid orbitals of Iodine with p orbitals of Fluorine. b. For CH2CHCH3, show the overlap of sp2 orbitals in the double bond and sp3 orbitals in the single bonds. c. For CH3SH, show the overlap of sp3 orbitals of Carbon and Sulfur with Hydrogen's s orbitals.

Key Concepts

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

Lewis Structures

Lewis structures are diagrams that represent the bonding between atoms in a molecule and the lone pairs of electrons that may exist. They are drawn by placing dots around the chemical symbols of the elements to indicate valence electrons, and lines are used to represent bonds. Understanding how to draw Lewis structures is essential for predicting molecular geometry and reactivity.
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VSEPR Theory

Valence Shell Electron Pair Repulsion (VSEPR) theory is a model used to predict the geometry of individual molecules based on the repulsion between electron pairs in the valence shell of the central atom. According to VSEPR, electron pairs will arrange themselves as far apart as possible to minimize repulsion, leading to specific molecular shapes such as linear, trigonal planar, or tetrahedral.
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Hybridization

Hybridization is the concept of mixing atomic orbitals to form new hybrid orbitals that can accommodate the bonding and lone pairs of electrons in a molecule. This process helps explain the geometry and bonding properties of molecules. For example, sp3 hybridization corresponds to a tetrahedral arrangement, while sp2 and sp hybridizations correspond to trigonal planar and linear geometries, respectively.
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Related Practice
Textbook Question

A molecule with the formula AB3 has a trigonal pyramidal geometry. How many electron groups are on the central atom (A)?

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Textbook Question

A molecule with the formula AB2 has a linear geometry. How many electron groups are on the central atom?

Textbook Question

For each molecular geometry, list the number of total electron groups, the number of bonding groups, and the number of lone pairs on the central atom. (c)

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