Textbook Question
If the dipole moment of CH3F is 1.847 D and the dipole moment of CD3F is 1.858 D, which is more electronegative: hydrogen or deuterium?
Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)
Bruice8th EditionOrganic ChemistryISBN: 9780135213711
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Table of contents
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 1)31
- Ch. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)65
- Ch. 2 - Acids and Bases: Central to Understanding Organic Chemistry84
- Ch. 3 - An Introduction to Organic Compounds:Nomenclature, Physical Properties, and Structure183
- Ch. 4 - Isomers: The Arrangement of Atoms in Space121
- Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics83
- Ch. 6 - The Reactions of Alkenes • The Stereochemistry of Addition Reactions175
- Ch. 7 - The Reactions of Alkynes • An Introduction to Multistep Synthesis119
- Ch. 8 - Delocalized Electrons: Their Effect on Stability, pKa, and the Products of a Reaction • Aromaticity and Electronic Effects: An Introduction to the Reactions of Benzene148
- Ch. 9 - Substitution and Elimination Reactions of Alkyl Halides212
- Ch. 10 - Reactions of Alcohols, Ethers, Epoxides, Amines, and Sulfur-Containing Compounds131
- Ch. 11 - Organometallic Compounds60
- Ch. 12 - Radicals90
- Ch. 13 - Mass Spectrometry; Infrared Spectroscopy; UV/Vis Spectroscopy62
- Ch. 14 - NMR Spectroscopy95
- Ch. 15 - Reactions of Carboxylic Acids and Carboxylic Acid Derivatives123
- Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives141
- Ch. 17 - Reactions at the Alpha-Carbon101
- Ch. 18 - Reactions of Benzene and Substituted Benzenes144
- Ch. 19 - More About Amines • Reactions of Heterocyclic Compounds49
- Ch. 20 - The Organic Chemistry of Carbohydrates80
- Ch. 21 - Amino Acids, Peptides, and Proteins57
- Ch. 22 - Catalysis in Organic Reactions and in Enzymatic Reactions35
- Ch. 23 - The Organic Chemistry of the Coenzymes—Compounds Derived from Vitamins1
- Ch. 28 - Pericyclic Reactions58
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Bruice 8th EditionCh. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)Problem 46d,e,f
Bruice 8th EditionCh. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)Problem 46d,e,fChapter 2, Problem 46d,e,f
Which of the following molecules would you expect to have a dipole moment of zero?
d. NH3
e. H2C═CH2
f. H2C═CHBr
Verified step by step guidance1
Analyze the molecular geometry of each molecule. The dipole moment depends on the shape of the molecule and the distribution of electron density. For NH₃, the geometry is trigonal pyramidal due to the lone pair on nitrogen, which creates an asymmetrical distribution of charge.
For H₂C═CH₂ (ethylene), examine the molecular geometry. The molecule is planar, and the two carbon atoms are sp² hybridized. The symmetry of the molecule causes the dipole moments of the C-H bonds to cancel out.
For H₂C═CHBr, consider the geometry and the presence of the bromine atom. Bromine is more electronegative than hydrogen, creating a polar bond. The molecule is not symmetrical, so the dipole moments do not cancel out.
Compare the symmetry and electronegativity differences in each molecule. Molecules with symmetrical geometries and equal distribution of electronegativity (like H₂C═CH₂) will have a dipole moment of zero, while asymmetrical molecules (like NH₃ and H₂C═CHBr) will have a net dipole moment.
Conclude that H₂C═CH₂ is the molecule with a dipole moment of zero due to its symmetrical planar geometry and equal distribution of charge.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Dipole Moment
A dipole moment is a measure of the separation of positive and negative charges in a molecule. It occurs when there is an uneven distribution of electron density, leading to a polar bond. Molecules with a dipole moment have a positive end and a negative end, while those with a dipole moment of zero are nonpolar, meaning their charge distribution is symmetrical.
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How dipole-dipole forces work.
Molecular Geometry
Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. The shape of a molecule significantly influences its dipole moment. For example, molecules with symmetrical shapes, such as linear or tetrahedral arrangements, often have dipole moments of zero, as the individual bond dipoles cancel each other out.
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Polarity of Bonds
The polarity of bonds is determined by the difference in electronegativity between the atoms involved. When two atoms with different electronegativities form a bond, the more electronegative atom attracts the shared electrons more strongly, creating a polar bond. In contrast, bonds between identical atoms or atoms with similar electronegativities are nonpolar, contributing to the overall polarity of the molecule.
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Related Practice
Textbook Question
Predict the approximate bond angles for
c. the H—C—N bond angle in (CH3)2NH.
d. the H—C—O bond angle in CH3OCH3
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Textbook Question
Which of the following molecules would you expect to have a dipole moment of zero?
a. CH3CH3
b. H2C═O
c. CH2Cl2
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Textbook Question
What is the hybridization of each of the C, N, and O atoms in the following compounds:
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Textbook Question
Which of the following molecules would you expect to have a dipole moment of zero?
g. BeCl2
h. BF3
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Textbook Question
Account for the difference in the shape and color of the potential maps for ammonia and the ammonium ion in Section 1.11.
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