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

1. A Review of General Chemistry

Resonance Structures

Organic Chemistry

1. A Review of General Chemistry

Resonance Structures

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5:53 minutes

Problem 6f

Textbook Question

Draw resonance contributors for each of the following species and rank them in order of decreasing contribution to the resonance hybrid. Then draw the resonance hybrid.
f.

Verified step by step guidance

Identify the species in question and determine if it has resonance structures. Resonance occurs when there are delocalized electrons, such as lone pairs, π-bonds, or charges, that can be redistributed across the molecule.

Draw all possible resonance contributors for the species. Use curved arrows to show the movement of electrons between resonance forms. Ensure that each resonance structure follows the rules of valence and does not violate the octet rule (except for exceptions like hypervalent atoms).

Evaluate the stability of each resonance contributor. Consider factors such as: (1) the number of covalent bonds (more bonds = more stable), (2) the presence of formal charges (fewer charges = more stable), (3) the placement of charges (negative charges on more electronegative atoms and positive charges on less electronegative atoms are more stable), and (4) the avoidance of charge separation.

Rank the resonance contributors in order of decreasing stability based on the evaluation in the previous step. The most stable contributor will contribute the most to the resonance hybrid, while less stable contributors will contribute less.

Draw the resonance hybrid by combining the resonance contributors. Use dashed lines to represent delocalized π-bonds or partial charges to indicate the distribution of charge across the molecule. The resonance hybrid reflects the weighted average of all contributors, with the most stable contributors having the greatest influence.

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Key Concepts

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

Resonance Structures

Resonance structures are different Lewis structures for the same molecule that depict the same arrangement of atoms but differ in the placement of electrons. These structures help illustrate the delocalization of electrons within a molecule, which contributes to its stability and reactivity. The actual structure of the molecule is a resonance hybrid, a weighted average of all valid resonance forms.

Resonance Hybrid

The resonance hybrid is the actual structure of a molecule that is represented as a combination of its resonance contributors. It reflects the delocalization of electrons across the molecule, resulting in bond lengths and angles that are intermediate between those predicted by individual resonance structures. The resonance hybrid is often more stable than any single resonance contributor due to this electron delocalization.

Stability of Resonance Contributors

The stability of resonance contributors is determined by factors such as the octet rule, charge distribution, and the presence of formal charges. Contributors that have full octets, minimal formal charges, and charge separation are generally more stable and thus contribute more to the resonance hybrid. Ranking these contributors involves assessing their stability to determine which structures are more significant in representing the molecule's true electronic structure.

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Draw resonance contributors for each of the following species and rank them in order of decreasing contribution to the resonance hybrid. Then draw the resonance hybrid. f.

Key Concepts

Resonance Structures

Resonance Hybrid

Stability of Resonance Contributors

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Draw resonance contributors for each of the following species and rank them in order of decreasing contribution to the resonance hybrid. Then draw the resonance hybrid.
f.