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]–
767
views
Ch.1 - Structure and Bonding
Wade9th EditionOrganic ChemistryISBN: 9780135213728
Not the one you use?Change textbookSelect a different textbook
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 7a,b,c
Draw the important resonance forms for the following molecules and ions.
(a) CO32–
(b) 
(c) 
Verified step by step guidance1
Identify the molecule or ion for which you need to draw resonance forms. In this case, we have carbonate ion (CO32-) and the allyl radical (H2C=CH—CH2).
For CO32-, recognize that it is a polyatomic ion with a charge of -2. The central carbon atom is bonded to three oxygen atoms. Start by drawing the Lewis structure with one double bond and two single bonds to the oxygen atoms.
Consider the movement of electrons to create resonance structures for CO32-. The double bond can shift between the oxygen atoms, creating equivalent resonance forms. Use arrows to indicate the movement of electrons from the double bond to form a new double bond with another oxygen atom, while the original double bond becomes a lone pair on the first oxygen.
For the allyl radical (H2C=CH—CH2), identify the pi bond between the first two carbon atoms and the unpaired electron on the third carbon. The resonance involves the movement of the pi electrons to form a new pi bond between the second and third carbon atoms, while the unpaired electron moves to the first carbon.
Draw the resonance structures for the allyl radical, showing the movement of electrons with curved arrows. Ensure that each resonance form maintains the correct number of electrons and follows the rules of resonance, such as conserving the total charge and maintaining the same number of unpaired electrons.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
8mWas this helpful?
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 a molecule or ion that depict the same arrangement of atoms but differ in the distribution of electrons. They are used to represent delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by a single Lewis structure. Understanding resonance is crucial for predicting the stability and reactivity of molecules.
Recommended video:
Guided course
03:04
Drawing Resonance Structures
Delocalization of Electrons
Delocalization refers to the spreading of electron density across multiple atoms, which occurs in molecules with conjugated systems or resonance. This phenomenon stabilizes the molecule by allowing electrons to be shared over several atoms, reducing electron-electron repulsion and lowering the overall energy. Delocalization is a key factor in the stability of resonance structures.
Recommended video:
Guided course
03:54The 18 and 16 Electron Rule
Formal Charge Calculation
Formal charge is a theoretical charge assigned to atoms in a molecule, calculated by assuming equal sharing of electrons in bonds. It is determined using the formula: Formal Charge = (Valence electrons) - (Non-bonding electrons) - (Bonding electrons/2). Calculating formal charges helps identify the most stable resonance structure, as structures with formal charges closest to zero are generally more stable.
Recommended video:
Guided course
01:34Calculating formal and net charge.
Related Practice
Textbook Question
Use electronegativities to predict the direction of the dipole moments of the following bonds.
(f) N—Cl
(g) N—O
(h) N—S
(i) N—B
(j) B—Cl
2459
views
Textbook Question
Draw the important resonance forms for the following molecules and ions.
(d) NO3–
(e) NO2–
(f)
1278
views
Textbook Question
Draw Lewis structures for the following compounds and ions, showing appropriate formal charges.
(e) +CH3
(f) –CH3
(g) NaBH4
(h) NaBH3CN
2205
views
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]+
757
views
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]+
2250
views