Chapter 5

Question 1

Define isomers

Answer 1

Different compounds with the same molecular formula

Question 2

What are the two different types of isomers?

Answer 2

Constitutional and stereoisomers

Question 3

Characteristics of constitutional isomers

Answer 3

• different IUPAC names

- different physical and chemical properties

Question 4

Characteristics of stereoisomers

Answer 4

same exact molecule just different spatial arrangement of their atoms

*different from stereochemistry

Question 5

Define configuration

Answer 5

3D arrangement

Question 6

Define superimposable

Answer 6

to align all parts of a molecule with its mirror image

ex: right and left socks are the same shape or each other

Question 7

Define achiral

Answer 7

a molecule that is superimposable

Question 8

Define chiral

Answer 8

a molecule that is non-superimposable

Question 9

What are the two types of stereoisomers?

Answer 9

Enantiomers and diastereomers

Question 10

Define enantiomers

Answer 10

A chiral stereoisomer which mirror image is not superimposable

Question 11

Define diastereomers

Answer 11

Stereoisomers that are not an enantiomer or a mirror image. May or may not be chiral

Question 12

Define a tetrahedral stereogenic center

Answer 12

A carbon atom bonded to four different groups

Question 13

Are cis and trans an enantiomer or a diastereomer?

Answer 13

ALWAYS a diastereomer

Question 14

When will a molecule be achiral?

Answer 14

when there is no stereogenic center

Question 15

If a molecule only has one stereogenic center, what is it always?

Answer 15

Chiral, nonsuperimposable enantiomer

Question 16

If a molecule has two or more stereogenic centers, is it chiral or achiral?

Answer 16

It depends

Question 17

Chiral centers have what type of hybridization?

Answer 17

Sp3

Question 18

What are the purpose of R and S

Answer 18

To differentiate between enantiomer pairs

Question 19

What is the first step in labeling R and S pairs?

Answer 19

Label the atom with the highest atomic number as 1 and work down atomic numbers

Question 20

What is rule #2 when labeling R or S

Answer 20

If there are two of the same atoms on the stereogenic center, the one that has branches w higher atomic numbers is higher in priority

Question 21

What makes a R configuration?

Answer 21

• H is in the back and 1-2-3-4 is clockwise

- H is in the front and 1-2-3-4 is counterclockwise

Question 22

What makes a S configuration?

Answer 22

• If H is in the back, and 1-2-3-4 is counterclockwise

- H is in front and 1-2-3-4 is clockwise

Question 23

How do you determine the max # of stereoisomers?

Answer 23

2^# of chiral centers

Question 24

Define mesocompound

Answer 24

A molecule with chiral centers but is achiral bc of mirror plane (perfect symmetry)

Question 25

What is important about mesocompounds?

Answer 25

The only have R vs. S groups... no r v. r or s v. s

Question 26

What is alpha in optical activity of chiral molecules?

Answer 26

Alpha is the angle of difference of light going into sample and light coming out

Question 27

Define dextrorotatory

Answer 27

Rotation to the right (+)

Question 28

Define levorotatory

Answer 28

Rotation to the left (-)

Question 29

What is the same about the rotation of a R and S enantiomer?

Answer 29

the magnitude of alpha is the same

Question 30

Define racemic mixtures

Answer 30

An equal amount of two enantiomers