Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

4. Alkanes and Cycloalkanes

Cis vs Trans

Organic Chemistry

4. Alkanes and Cycloalkanes

Cis vs Trans

Previous problemNext problem

6:29 minutes

Problem 56a,b

Textbook Question

a. Draw the structure of cis-CH₃CH=CHCH₂CH₃ showing the pi bond with its proper geometry.
b. Circle the six coplanar atoms in this compound.

Verified step by step guidance

Identify the structure of the compound: cis-CH3CH=CHCH2CH3. This is a pentene molecule with a double bond between the second and third carbon atoms.

Draw the carbon chain: Start by drawing a five-carbon chain. Label the carbons as C1, C2, C3, C4, and C5 from left to right.

Add the double bond: Place a double bond between C2 and C3. Since the compound is 'cis', ensure that the CH3 group on C1 and the CH2CH3 group on C4 are on the same side of the double bond.

Show the geometry of the pi bond: The double bond consists of a sigma bond and a pi bond. The pi bond is formed by the sideways overlap of p orbitals, which are perpendicular to the plane of the sigma bond. Draw the p orbitals on C2 and C3 to illustrate the pi bond.

Circle the six coplanar atoms: In a cis-alkene, the atoms involved in the double bond and the atoms directly attached to them are coplanar. Circle the atoms: C1, C2, C3, C4, and the two hydrogen atoms attached to C2 and C3, as these are the six coplanar atoms in the molecule.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

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

Cis-Trans Isomerism

Cis-trans isomerism is a form of stereoisomerism where the relative orientation of functional groups differs around a double bond. In cis isomers, similar groups are on the same side, while in trans isomers, they are on opposite sides. This affects the molecule's geometry and physical properties.

Pi Bond Geometry

Pi bonds are formed by the sideways overlap of p orbitals, creating a region of electron density above and below the plane of the atoms involved. In alkenes, the pi bond restricts rotation, resulting in a planar geometry around the double bond, which is crucial for understanding molecular shape and reactivity.

Coplanar Atoms

Coplanar atoms are atoms that lie in the same geometric plane. In molecules with double bonds, such as alkenes, the atoms directly involved in and adjacent to the double bond are typically coplanar due to the rigidity imposed by the pi bond, affecting the molecule's overall shape and interactions.