Textbook Question
For each of the following compounds, draw the important resonance forms. Indicate which structures are major and minor contributors or whether they have the same energy.
(d) [H2CNO2]–
3
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Ch.1 - Structure and Bonding
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 1, Problem 7d,e,f
Draw the important resonance forms for the following molecules and ions.
(d) NO3–
(e) NO2–
(f) 
Verified step by step guidance1
Identify the molecule or ion for which you need to draw resonance structures. For NO3- (nitrate ion), NO2- (nitrite ion), and HCOCH=CHCH2- (a carbonyl compound with an allylic anion), start by drawing the Lewis structure.
For NO3-, draw the central nitrogen atom bonded to three oxygen atoms. Include a negative charge on one of the oxygen atoms. Consider the possibility of delocalizing the negative charge across the oxygen atoms to form resonance structures.
For NO2-, draw the central nitrogen atom bonded to two oxygen atoms. Place a negative charge on one of the oxygen atoms. Explore the resonance structures by moving the negative charge and forming double bonds with the nitrogen atom.
For HCOCH=CHCH2-, identify the allylic position (the carbon atom adjacent to the double bond) where the negative charge is located. Draw resonance structures by moving the pi electrons of the double bond to form new double bonds and shift the negative charge.
Ensure that all resonance structures obey the rules of resonance: atoms must remain in the same positions, only electrons move, and the overall charge of the molecule or ion remains constant. Check that each structure has valid Lewis structures with complete octets where applicable.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Resonance
Resonance in organic chemistry refers to the phenomenon where a molecule or ion can be represented by two or more valid Lewis structures, known as resonance forms. These forms differ only in the placement of electrons, not atoms, and help depict the delocalization of electrons within the molecule, providing a more accurate representation of its electronic structure.
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Formal Charge
Formal charge is a concept used to determine the charge distribution within a molecule. It is calculated by assuming equal sharing of electrons in bonds and comparing the number of valence electrons in an isolated atom to those assigned in the molecule. Understanding formal charge helps in identifying the most stable resonance structures, as structures with minimized formal charges are generally more stable.
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01:34Calculating formal and net charge.
Electron Delocalization
Electron delocalization is the spreading of electron density across multiple atoms, which occurs in molecules with conjugated systems or resonance. This delocalization stabilizes the molecule by lowering its energy, and is often depicted in resonance structures. Recognizing electron delocalization is crucial for drawing resonance forms, as it explains the distribution of electrons across the molecule.
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Related Practice
Textbook Question
Draw the important resonance forms for the following molecules and ions.
(a) CO32–
(b)
(c)
1
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Textbook Question
Draw Lewis structures for the following compounds and ions, showing appropriate formal charges.
(e) +CH3
(f) –CH3
(g) NaBH4
(h) NaBH3CN
1
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Textbook Question
For each of the following compounds, draw the important resonance forms. Indicate which structures are major and minor contributors or whether they have the same energy.
(c) [H2COCH3]+
2
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Textbook Question
Draw Lewis structures for the following compounds and ions, showing appropriate formal charges.
(i) (CH3)2O—BF3
(j) [HONH3]+
(k) KOC(CH3)3
(l) [H2C=OH]+
8
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Textbook Question
For each of the following compounds, draw the important resonance forms. Indicate which structures are major and minor contributors or whether they have the same energy.
(e) [CH3C(OH)2]+
(f) [CH2CHNH]–
1
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