Textbook Question
Use the symbols δ+ and δ− to show the direction of the polarity of the indicated bond in each of the following compounds:
g. I—Cl
h. H2N—OH
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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 13
Bruice 8th EditionCh. 1 - Remembering General Chemistry: Electronic Structure and Bonding (Part 2)Problem 13Chapter 2, Problem 13
Explain why HCl has a smaller dipole moment than HF, even though the H—Cl bond is longer than the H—F bond.
Verified step by step guidance1
Dipole moment (μ) is calculated using the formula: , where is the magnitude of the charge separation and is the bond length. While bond length () is a factor, the magnitude of the charge separation () plays a critical role in determining the dipole moment.
The electronegativity of fluorine (F) is significantly higher than that of chlorine (Cl). This means that the electron density in the H—F bond is pulled more strongly toward the fluorine atom, resulting in a larger charge separation () compared to the H—Cl bond.
Although the H—Cl bond is longer than the H—F bond, the smaller charge separation in the H—Cl bond due to chlorine's lower electronegativity reduces its contribution to the dipole moment.
In the case of H—F, the combination of a shorter bond length and a much larger charge separation results in a higher dipole moment compared to H—Cl.
Thus, the smaller dipole moment of HCl is primarily due to the lower electronegativity of chlorine, which leads to a smaller charge separation, even though the bond length is longer.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Electronegativity
Electronegativity is a measure of an atom's ability to attract and hold onto electrons in a chemical bond. In the case of HCl and HF, fluorine is more electronegative than chlorine, which means that the H—F bond has a greater polarity. This difference in electronegativity contributes significantly to the dipole moment, as the more electronegative atom (F) pulls the electron density closer, creating a stronger dipole.
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Electronegativity
Bond Length and Dipole Moment
The dipole moment of a molecule is influenced by both the bond length and the difference in electronegativity between the bonded atoms. Although H—Cl is longer than H—F, the dipole moment is not solely determined by bond length. The greater electronegativity of fluorine results in a stronger dipole moment in HF, despite the shorter bond length, leading to a higher overall dipole moment compared to HCl.
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Vector Nature of Dipole Moments
Dipole moments are vector quantities, meaning they have both magnitude and direction. The overall dipole moment of a molecule is the vector sum of the individual bond dipoles. In HCl, the bond dipole is less significant due to the lower electronegativity of chlorine compared to fluorine, resulting in a smaller net dipole moment for HCl, despite the longer bond length.
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Related Practice
Textbook Question
Use the symbols δ+ and δ− to show the direction of the polarity of the indicated bond in each of the following compounds:
e. HO—Br
f. H3C—Li
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Textbook Question
Draw two Lewis structures for C2H6O.
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Textbook Question
Use the symbols δ+ and δ− to show the direction of the polarity of the indicated bond in each of the following compounds:
c. H3C—NH2
d. H3C—Cl
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Textbook Question
After examining the potential maps for LiH, HF, and H2, answer the following questions:
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a. Which compounds are polar?
b. Why does LiH have the largest hydrogen?
c. Which compound has the hydrogen that would be most apt to attract a negatively charged molecule?
Textbook Question
Draw the Lewis structure for each of the following:
f. NaOH
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