The Foundations of Chemistry

Exercises 1105

CONCEPTUAL EXERCISES

*121.Suggest why the C 6 ring in cyclohexane is not planar.

*122.Can an aromatic compound also be a saturated com-

pound?

BUILDING YOUR KNOWLEDGE

*123.(a) How do the melting points and boiling points of the

alkanes vary with molecular weight? (b) Do you expect

them to vary in this order? (c) Why or why not? Use

intermolecular forces to explain your answer.

*124.Write a Lewis formula for butanone.

*125.(a) What are resonance structures? (b) Draw resonance

structures for benzene. (c) What do we mean when we

say that the electrons associated with the bonds in ben-

zene are delocalized over the entire ring?

*126.Lidocaine has replaced Novocain (procaine) as the

favored anesthetic in dentistry. What functional group do

the two compounds have in common?

H 2 N

O

COCH 2 CH 2 N(CH 2 CH 3 ) 2

Novocain

NH

CH 3

O

CH 3

CCH 2 N(CH 2 CH 3 ) 2

lidocaine