Explanations 
Textbooks 
Flashcards 
91影视 AI 
Notes 
Study Plans 
Study Sets 
Find a degree 
Magazine Chapter 4: Problem 120
The molecules that will have dipole moment: (1) 2, 2-dimethylpropane (2) Trans-1-pent-2-ene (3) Cis-hex-3-ene (4) 2, 2, 3, 3-tetramethylbutane (a) 2,3 (b) 1,3 (c) \(1,2,3\) (d) all of these
Short Answer
Expert verified
(b) 1,3 only cis-hex-3-ene has a dipole moment.
Step by step solution
01
Understand Dipole Moment
Dipole moment arises when there is an asymmetrical charge distribution within a molecule. This typically happens when there are polar bonds and asymmetrical geometries (no symmetry that cancels polarity out). We need to check each given molecule for these features.
02
Analyze 2,2-Dimethylpropane
2,2-Dimethylpropane is a branch-structured hydrocarbon with plenty of symmetry, as all of its C-C bonds and C-H bonds are nonpolar. Therefore, this molecule is nonpolar and has a dipole moment of zero.
03
Analyze Trans-1-Pent-2-ene
Trans isomers have a symmetry that often cancels out their dipole moments. In trans-1-pent-2-ene, the large groups are across from each other on the double bond, leading to symmetric charge distribution and no overall dipole moment.
04
Analyze Cis-Hex-3-ene
Cis isomers do not have symmetry that cancels out dipole moments because groups are on the same side of the double bond. In cis-hex-3-ene, the positioning causes an asymmetrical distribution of charge, resulting in a net dipole moment.
05
Analyze 2,2,3,3-Tetramethylbutane
Like 2,2-dimethylpropane, 2,2,3,3-tetramethylbutane is highly symmetrical. All the substituents are arranged symmetrically, and the molecule is nonpolar with a net dipole moment of zero.
06
Determine Which Have a Dipole Moment
From the analysis, the molecules with dipole moments are those that lack symmetry that can cancel out polarity. Only cis-hex-3-ene fits this description, as it has an asymmetrical charge distribution.
Unlock Step-by-Step Solutions & Ace Your Exams!
-
Full Textbook Solutions
Get detailed explanations and key concepts
-
Unlimited Al creation
Al flashcards, explanations, exams and more...
-
Ads-free access
To over 500 millions flashcards
-
Money-back guarantee
We refund you if you fail your exam.
Over 30 million students worldwide already upgrade their learning with 91影视!
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Molecular Symmetry
Understanding molecular symmetry is crucial in determining if a molecule has a dipole moment. A molecule is symmetrical when its parts are arranged in a balanced way around a central point or along a central axis. This symmetry can greatly influence the molecule's properties. When a molecule is symmetrical, the forces or charges may cancel out.
For instance:
For instance:
- In symmetrical molecules, like 2,2-dimethylpropane and 2,2,3,3-tetramethylbutane, the symmetry ensures that any charge distribution is evenly spread, leading to a net dipole moment of zero.
- For asymmetrical molecules, the charge distribution is uneven, leading to a net dipole moment. This is seen in cis-hex-3-ene, where the lack of symmetry results in a molecule that has a dipole moment due to an uneven charge distribution.
Polar Bonds
Polar bonds occur when there is a difference in electronegativity between two bonded atoms. Electronegativity is a measure of how strongly an atom attracts electrons in a bond. When an atom with a higher electronegativity bonds with one of lower electronegativity, electrons tend to be more pulled towards the more electronegative atom, creating a polar bond.
Key points about polar bonds:
Key points about polar bonds:
- Polar bonds have a dipole, where one end is slightly positive (less electronegative atom) and the other is slightly negative (more electronegative atom).
- These types of bonds contribute to the overall dipole moment of a molecule. If polar bonds are symmetrically arranged, their effects may cancel out, resulting in a nonpolar molecule despite the presence of polar bonds.
- In molecules like cis-hex-3-ene, the polar bonds contribute to a net dipole moment because their asymmetrical arrangement prevents cancellation.
- In symmetric molecules like trans-1-pent-2-ene, any polarity in individual bonds is canceled, rendering the overall molecule nonpolar.
Cis-Trans Isomerism
Cis-trans isomerism is a type of stereoisomerism found in alkenes, where similar groups are positioned differently around a double bond. This bonding creates two possibilities: **cis**, where similar groups are on the same side, and **trans**, where they are on opposite sides.
Differences between cis and trans isomers:
Differences between cis and trans isomers:
- **Cis isomers** can result in a polar molecule due to asymmetrical arrangement. For example, in cis-hex-3-ene, substituents are on the same side of the double bond, causing an uneven charge distribution and resulting in a dipole moment.
- **Trans isomers,** like trans-1-pent-2-ene, often lead to nonpolar molecules because the placement of groups across the double bond balances out any charge distribution, often leading to no net dipole moment.
