MS 902 - Formal Charge and Resonance

Submitted by Matt on August 6, 2011.

Textbook and Chapter: Carey and Giuliano 8th Ed. (2010), Chapter 1

Keywords: formal charge, Lewis structures, resonance

Description: This mendel set goes through the basics of structure:

Converting between formulas and carbon skeleton diagrams ("Zig-zag" structures)
Determining formal charge
Identifying implicit hydrogens and lone pairs
Resonance and arrow pushing

Total Problems: 7

Printer-friendly version

Problem # 309

Convert each formula to a carbon skeleton diagram, or vice-versa.
Solution

Problem Details
MendelSet practice problem # 309 submitted by Matt on June 7, 2011.
Subject: Organic Chemistry
Subject Topic(s): Lewis Structures, Formal Charges, and Resonance
Question Type: Concept (explain why this is so..)
Keyword(s): Lewis structures
Problem # 310

For each molecule, determine the formal charge of the indicated atom.
Solution
Remember that when calculating formal charge, you count both electrons in a lone pair but only half of the electrons in a bonding pair. This is why a helpful formula is:

formal charge = (# of valence e^-) - ("sticks + dots")

For example, in the first compound (the protonated oxygen), the oxygen has one lone pair ("2 dots") and three bonding pairs ("3 sticks"). Oxygen has a valence of 6, so its formal charge in this species is 6 - 5 = 1 or +1.

Problem Details
MendelSet practice problem # 310 submitted by Matt on June 7, 2011.
Subject: Organic Chemistry
Subject Topic(s): Lewis Structures, Formal Charges, and Resonance
Question Type: Concept (explain why this is so..)
Keyword(s): formal charge
Problem # 311

For each molecule below, draw in all implied lone pairs and/or protons (hydrogens) based on the formal charge shown.
Solution
Being able to determine implied lone pairs and/or hydrogens is a good skill to have, as its likely that much of the time your professor or TA will not write in all lone pairs, and will almost never draw in the implicit hydrogens. Until you are very comfortable with formal charges, you should always draw in all lone pairs and hydrogens on each atom.

Problem Details
MendelSet practice problem # 311 submitted by Matt on June 7, 2011.
Subject: Organic Chemistry
Subject Topic(s): Lewis Structures, Formal Charges, and Resonance
Question Type: Concept (explain why this is so..)
Keyword(s): formal charge
Problem # 312

Draw all possible resonance forms for each structure below. Use curved arrows.

Note that some structures only show charge, and not implied protons or lone pairs!
Solution

Problem Details
MendelSet practice problem # 312 submitted by Matt on June 7, 2011.
Subject: Organic Chemistry
Subject Topic(s): Lewis Structures, Formal Charges, and Resonance
Question Type: Concept (explain why this is so..)
Keyword(s): resonance
Problem # 313

Draw all possible resonance forms for each structure below. Use curved arrows.

Note that some structures only show charge, and not implied protons or lone pairs!
Solution

Problem Details
MendelSet practice problem # 313 submitted by Matt on June 7, 2011.
Subject: Organic Chemistry
Subject Topic(s): Lewis Structures, Formal Charges, and Resonance
Question Type: Concept (explain why this is so..)
Keyword(s): resonance, carbanion
Problem # 314

Draw all possible resonance forms for each structure below. Use curved arrows.

Note that some structures only show charge, and not implied protons or lone pairs!
Solution

Problem Details
MendelSet practice problem # 314 submitted by Matt on June 7, 2011.
Subject: Organic Chemistry
Subject Topic(s): Lewis Structures, Formal Charges, and Resonance
Question Type: Concept (explain why this is so..)
Keyword(s): resonance
Problem # 315

Draw all possible resonance forms for each structure below. Use curved arrows.

Note that some structures only show charge, and not implied protons or lone pairs!
Solution
Notice that when drawing resonance forms with positive charges, the arrows never come from the positive charge. Arrows only come from π (pi) electrons- lone pairs or double/triple bonds.

Problem Details
MendelSet practice problem # 315 submitted by Matt on June 7, 2011.
Subject: Organic Chemistry
Subject Topic(s): Lewis Structures, Formal Charges, and Resonance
Question Type: Concept (explain why this is so..)
Keyword(s): resonance, carbocation

Follow MendelSet on Twitter, become a fan on Facebook.

Printer-friendly version

MS 902 - Formal Charge and Resonance

MS 902 - Formal Charge and Resonance

Login