Textbook Question
(b) An AB4 molecule has two lone pairs of electrons on the A atom (in addition to the four B atoms). What is the electron-domain geometry around the A atom?
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Ch.9 - Molecular Geometry and Bonding Theories
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970
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Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement111
- Ch.2 - Atoms, Molecules, and Ions166
- Ch.3 - Chemical Reactions and Reaction Stoichiometry138
- Ch.4 - Reactions in Aqueous Solution127
- Ch.5 - Thermochemistry104
- Ch.6 - Electronic Structure of Atoms109
- Ch.7 - Periodic Properties of the Elements107
- Ch.8 - Basic Concepts of Chemical Bonding102
- Ch.9 - Molecular Geometry and Bonding Theories120
- Ch.10 - Gases122
- Ch.11 - Liquids and Intermolecular Forces79
- Ch.12 - Solids and Modern Materials102
- Ch.13 - Properties of Solutions99
- Ch.14 - Chemical Kinetics153
- Ch.15 - Chemical Equilibrium83
- Ch.16 - Acid-Base Equilibria109
- Ch.17 - Additional Aspects of Aqueous Equilibria117
- Ch.18 - Chemistry of the Environment60
- Ch.19 - Chemical Thermodynamics109
- Ch.20 - Electrochemistry113
- Ch.21 - Nuclear Chemistry79
- Ch.22 - Chemistry of the Nonmetals52
- Ch.23 - Transition Metals and Coordination Chemistry57
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry7
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Not the one you use?Change textbook
Chapter 9, Problem 18
Describe the bond angles to be found in each of the following molecular structures: (a) trigonal planar, (b) tetrahedral, (c) octahedral, (d) linear.
Verified step by step guidance1
Identify the molecular geometry for each structure: (a) trigonal planar, (b) tetrahedral, (c) octahedral, (d) linear.
Recall that the bond angles are determined by the electron pair geometry around the central atom.
For (a) trigonal planar, the bond angles are typically 120° due to the arrangement of three electron pairs around the central atom.
For (b) tetrahedral, the bond angles are typically 109.5° as four electron pairs are arranged in a three-dimensional space.
For (c) octahedral, the bond angles are typically 90° because six electron pairs are symmetrically arranged around the central atom, and for (d) linear, the bond angles are 180° as two electron pairs are directly opposite each other.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Molecular Geometry
Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. It is determined by the number of bonding pairs and lone pairs of electrons around the central atom, which influences the shape and angles between bonds. Understanding molecular geometry is crucial for predicting bond angles and the overall structure of molecules.
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01:33
Molecular Geometry with Two Electron Groups
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 to minimize repulsion, leading to specific bond angles characteristic of different molecular shapes, such as trigonal planar or tetrahedral.
Recommended video:
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02:13Molecular Shapes and VSEPR
Bond Angles
Bond angles are the angles formed between adjacent bonds in a molecule, which are influenced by the molecular geometry. For example, in a trigonal planar structure, bond angles are approximately 120 degrees, while in a tetrahedral structure, they are about 109.5 degrees. Understanding these angles is essential for predicting the behavior and reactivity of molecules.
Recommended video:
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01:53Bond Angles
Related Practice
Textbook Question
b. The NH3 molecule is trigonal pyramidal, while BF3 is trigonal planar. Which of these molecules is flat?
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Textbook Question
For each of these contour representations of molecular orbitals, identify (c) whether the MO is bonding or antibonding (i)
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Textbook Question
a. Methane (CH4) and the perchlorate ion (ClO4−) are both described as tetrahedral. What does this indicate about their bond angles?
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Textbook Question
In which of the following molecules can you confidently predict the bond angles about the central atom, and for which would you be a bit uncertain? Explain in each case. (a) H2S, (b) BCl3, (c) CH3I, (d) CBr4, (e) TeBr4.
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