Video Solution: In each of the following pairs, determine whether the two re...

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In each of the following pairs, determine whether the two represent resonance contributors of a single species or depict different substances. If two structures are not resonance contributors, explain why. 

Video Transcript

So, let's go ahead and pay attention to these two molecules up here, this pair and figure out if they're resonance structures of if they're entirely different molecules. Remember, for resonance structures a couple of rules that we need to follow, right? one we can't have our atoms moving around right, only electrons move, the next rule is that we have the same number of electrons and as a consequence to that our net charge on the molecule will stay the same, right? No matter what arrangement it's in, you can have two negatives and a positive but you have a negative one charge net, right? You should expect the negative one charge to remain throughout all your other resonance structures for example, right? It could be any charge, so now let's go ahead and take a look and figure out our formal charges, so this one has three lone pairs and one bond, right? We know the nitrogen likes to have three bonds and one lone pair, so this has a two negative charge, right? this guy over here, we can also do our sticks plus dots, right? So, our group number is five minus 1 stick and 6 dots, right? So that's five minus seven, that's going to give us negative two, this next one over here, nitrogen likes to have three bonds and one lone pair but it's got four bonds here, so it's got a positive charge, right? And then this next one has a 1, 2, 3, right? 3 bonds and a lone pair, which is exactly what it wants so it's got a net zero charge, okay? So this whole thing, this whole molecule has a net charge of negative one. Alright, so now this next one here, this has two bonds and two lone pairs, so it's got a negative charge, this one has a positive charge, so it's also got four bonds just like this one, right? And then this one over here has a negative charge, so the net of this molecule is a negative charge, so what does that tell me? that tells me guys that these are resonance structures, okay? So if you have any questions please feel free to let me know, if not, let's move on to the next problem.

Draw all of the resonance forms in complete skeletal form for the following molecule. Label the BEST resonance form.

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Which structures below are resonance forms of the carbocation shown in the box below?

a) III only

b) I and II only

c) I and III only

d) II and IV only

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Consider the molecule below:

a) Name the molecule. 

b) Draw another resonance contributor; use the correct arrows to show electron movement and the relationship between the contributors.

c) Draw the molecular dipole.

d) Draw a hydroxide ion and show how this ion could "attack" the molecule that you've named. Use the correct arrows to show electron attack and the equilibrium between the two species. 

e) Use the correct arrows to indicate the resonance contributor.

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Which of the following resonance forms best represent the molecule diazomethane?

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Draw two additional resonance structures for the following compound.

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Draw all of the reasonable resonance structures for the following molecule. 

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In the spaces provided, draw all the important resonance contributing structures of the indicated species. We have provided template molecules to help you do this more quickly. You must draw all pi bonds, all lone pairs of electrons and all formal charges on each of your structures. You DO NOT need to draw arrows to show electron movement.

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Amides are best represented as the hybrid of three contributing structures. Draw the second and third important contributing structures in the spaces provided, including all lone pairs and formal charges. For the two structures on the left in each problem, use arrows to indicate the movement of electrons to give the structures you drew. There is no need to draw any circles around any of these contributing strucures. You might want to read these directions again to make sure you know what we want

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Draw the important resonance structues for the following ion. Using arrows, show all electron movements. 

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Draw the important resonance structues for the following ion. Using arrows, show all electron movements. 

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Draw two major resonance forms for the following molecule.

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Consider the anion below, which is a resonance hybrid. Only one important resonance structure is given – each additional important resonance structure only has one atom with a nonzero formal charge. Several of the carbon atoms in the given resonance structure are labeled. Which of these carbon atoms has a  negative formal charge on it in  any of the additional important resonance structures that are not shown? Pick the one choice below which best answers this question.

A. I only

B. II only

C. III only

D. IV only

E. I and III

F. II and IV

G. I and II

H. III and IV

I. I, II, III, and IV

J. None of these

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Which choice best describes the relationship that exists between the pair of structures?

A. Identical 

B. Constitutional isomers

C. Resonance structures 

D. No relationship exists

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Which choice best describes the relationship that exists between the pair of structures?

A. Identical

B. Constitutional isomers

C. Resonance structures

D. No relationship exists

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What is the total number of valence electrons that should be shown explicitly as bonding pairs and/or lone pairs in each contributing resonance structure of HCO 3– ?

A. 24

B. 25

C. 26

D. 27

E. 28

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Starting from the structure below, draw three (3) additional resonance forms that are also  more significant contributors. Clearly circle the  most important resonance form. 

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Draw  three  other important resonance contributors for the molecule below.

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Which pair consists of resonance structures?

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Onto which of the numbered atoms in the following structure can the negative charge be moved by drawing resonance structures?

a) 1, 3, 5 only

b) 2, 4, 6 only

c) 2, 4, 6, 8

d) 1, 3, 5, 7

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Draw the three formal resonance structures of the carbonate ion  (CO 32-) below.

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What is the definition of a resonance structure?

a) Compounds with the same molecular formula

b) Compounds with different carbon frameworks

c) Structues that differ only in the placement of pi and nonbonding electrons

d) Structures that differ only in the locations of bonds

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Draw as many resonance structures as you can for the following compounds (Do not draw the same resonance structure twice). Circle the weaker base, and briefly justify your answer. 

 

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Identify the false statement

(A) p molecular orbitals are formed by overlap of p atomic orbitals.

(B) Orbitals are mathematical functions describing the energy of an electron in an atom.

(C) Contributing structures are in equilibrium with each other.

(D) Contributing structures have the same arrangement of atoms but a different arrangement of electrons.

(E) Functional groups are the sites of greatest reactivity in an organic molecule. 

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Draw two resonance structures for the species below.

 

 

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Draw in the appropriate arrows for the following resonance structures. 

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Which pair represents resonance structures?

a. I

b. II

c. III

d. IV

e. More than one of the above

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Which is (are) correct resonance structure(s) for the following organic compound:

a. I

b. II and III

c. I and II

d. All of the above

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Which is (are) correct resonance structure(s) for the following organic compound:

a. I

b. II and III

c. I and III

d. All of the above

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