Question 1

Which molecular representation provides the most information about the connectivity and geometry of a molecule such as amoxicillin?

Accepted Answer

Bond-line (skeletal) structure

Question 2

Why is the molecular formula insufficient for distinguishing between propanol and isopropanol?

Accepted Answer

It does not indicate the connectivity of atoms

Question 3

In a bond-line structure, how are carbon atoms represented?

Accepted Answer

By the endpoints and corners of lines

Question 4

How many hydrogen atoms are implied on a carbon atom in a bond-line structure that is bonded to two other carbons and no heteroatoms?

Accepted Answer

$$2$$

Question 5

Which rule must always be followed when drawing bond-line structures for organic molecules?

Accepted Answer

Never draw more than four bonds to a carbon atom

Question 6

Which functional group transformation is most easily identified using bond-line structures compared to condensed formulas?

Accepted Answer

Alkane to alkene

Question 7

A carbon atom with a positive formal charge (carbocation) will have:

Accepted Answer

$$3$$ bonds and one empty orbital

Question 8

Which of the following is TRUE about lone pairs in bond-line structures?

Accepted Answer

Lone pairs are often omitted, but their presence is implied by formal charge

Question 9

In a 3D bond-line structure, what does a solid wedge represent?

Accepted Answer

A bond coming out of the plane of the paper toward the viewer

Question 10

Which of the following statements about resonance is correct?

Accepted Answer

Resonance delocalizes electrons in overlapping p orbitals

Question 11

Which curved arrow movement is NOT allowed when drawing resonance structures?

Accepted Answer

Breaking a single (sigma) bond

Question 12

Which of the following resonance patterns involves a lone pair adjacent to a carbocation?

Accepted Answer

Lone pair adjacent to a carbocation

Question 13

Which resonance contributor is most significant according to the rules for assessing resonance structures?

Accepted Answer

The structure with the greatest number of filled octets

Question 14

A resonance structure with a negative charge on an oxygen atom and a full octet is generally:

Accepted Answer

More significant than a structure with a negative charge on carbon

Question 15

Which of the following best describes a resonance hybrid?

Accepted Answer

A blend of all resonance contributors, representing the actual structure

Question 16

In the allyl carbocation, how is the positive charge distributed according to molecular orbital theory?

Accepted Answer

Delocalized over both terminal carbon atoms

Question 17

Which of the following statements about delocalized lone pairs is correct?

Accepted Answer

Delocalized lone pairs must be adjacent to an atom with an unhybridized p orbital

Question 18

Which general guideline helps determine if a lone pair is localized or delocalized?

Accepted Answer

If the atom has both a pi bond and a lone pair, only one will participate in resonance

Question 19

Which resonance pattern is present in benzene?

Accepted Answer

Conjugated pi bonds in a ring

Question 20

A student draws a resonance structure for a molecule with a second-row element (carbon) having nine electrons in its valence shell. What is wrong with this structure?

Accepted Answer

It violates the octet rule for second-row elements

Chapter 2: Molecular Representations – Study Notes

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