Ch4

Question 1

two types of isomers

Answer 1

constitutional isomer, stereoisomers

Question 2

Constitutional isomer

Answer 2

differ int he way their atoms are connected / connected differently

Question 3

stereoisomer

Answer 3

connected in the same way, differ in the way their atoms are arranged in space.

Question 4

two kinds of stereoisomer

Answer 4

conformational isomers and configurational isomers.

Question 5

conformational isomers

Answer 5

conformers/ stereoisomers that rapidly interconvert at room temperature, because they interconvert they cannot be separated

Question 6

configurational isomers

Answer 6

stereoisomers that cannot interconvert unless covalent bonds are broken, because they cannot interconvert configurational isomers can be separated.

Question 7

two kinds of conformational isomer

Answer 7

rotation about carbon-carbon single bonds/ amine inversion

Question 8

two kinds of configurational isomers

Answer 8

cis-trans isomers, and isomers that contain asymmetric centers

Question 9

other name of the cis-trans isomers

Answer 9

geometric isomer

Question 10

the ____ isomer has its substituents on the same side of the ring; the ____ isomer has its substituents on opposite sides of the ring

Answer 10

cis, trans

Question 11

rotation about a double bond occurs only when?

Answer 11

only if the pi bond breaks

Question 12

the compound with the hydrogens on the same side of the double bond is called the ____ isomer

Answer 12

cis

Question 13

the compound with the hydrogens on the opposite side of the double bond is called the ____ isomer

Answer 13

trans

Question 14

cis and trans isomers have the same molecular formula and the same bonds but have different _______ they differ in the way their atoms are oriented in space

Answer 14

configurations

Question 15

if one of the sp^2 carbons is attached to two identical substituents, then the compound cannot have ________________

Answer 15

cis and trans isomers

Question 16

cis and trans isomers can be separated from each other because they are different compounds with different______

Answer 16

physical properties

Question 17

____________ is used to name alkenes that do not have a hydrogen attached to each of the sp^2 carbons

Answer 17

E,Z system

Question 18

Z isomer

Answer 18

has the high-priority groups on the same side of the double bond

Question 19

E isomer

Answer 19

has the high-priority groups on opposite sides of the double bond

Question 20

object with a right-handed and a left-handed form is said to be ?

Answer 20

chiral

Question 21

a chiral object has a

Answer 21

nonsuperimposable mirror image, in other words its mirror image does not look the same as an image of the object itself.

Question 22

objects that are not chiral are said to be?

Answer 22

achiral, an achiral object has a superimposable mirror image

Question 23

______________ is an atom bonded to four different groups.

Answer 23

asymmetric center

Question 24

a compound with one asymmetric center can exist as

Answer 24

two stereoisomers

Question 25

molecules that are nonsuperimposable mirror images of each other are called?

Answer 25

enantiomers

Question 26

asymmetric center is also called?

Answer 26

stereocenter, stereogenic center however, stereocenter is an atom at which the interchange of two groups produces a stereoisomer, thus stereocenters include both asymmetric centers and the sp^2 carbons of an alkene or the sp^3 carbons of a cyclic compound, where the interchange of two groups converts a cis isomer to a trans isomer or vice versa.

Question 27

although all _________ are stereocenters, not all stereocenters are _________

Answer 27

asymmetric center

Question 28

a system of nomenclature for enantiomer pairs

Answer 28

R configuration and S configuration

Question 29

R configuration _____________arrow, S configuration ______________arrow

Answer 29

clockwise, counterclockwise

Question 30

Enantiomers share many of the same properties, including the same bp, melting point, solubilities except those that stem from _________________________

Answer 30

how the groups bonded to the asymmetric center are arranged in space / Eg: the way they interact with plane-polarized light

Question 31

when plane-polarized light passes through a solution of achiral molecules, the light emerges from the solution with its plane of polarization _______

Answer 31

unchanged

Question 32

when plane-polarized light passes through a solution of chiral molecules, the light emerges from the solution with its plane of polarization _______

Answer 32

rotated either clockwise or counterclockwise

Question 33

a compound that rotates the plane of polarization of plane-polarized light is said to be ______

Answer 33

optically active

Question 34

achiral compounds are optically ?

Answer 34

inactive

Question 35

if an optically active compound rotates the plane of polarization clockwise, then the compound is said to be?

Answer 35

dextrorotatory( indicated by +)

Question 36

if an optically active compound rotates the plane of polarization counterclockwise, then the compound is said to be?

Answer 36

levorotatory( indicated by -)

Question 37

the direction and amount an optically active compound rotates the plane of polarization of plane- polarized light can be measured with an instrument called?

Answer 37

polarimeter

Question 38

observed rotation is dependent on

Answer 38

concentration of the sample, and the length of the sample tube, the rotation also depends on the temperature and the wavelength of the light source

Question 39

if one enantiomer has a specific rotation of +5.75 the other has?

Answer 39

-5.75

Question 40

racemic mixture or racemate

Answer 40

a mixture of equal amounts of two enantiomers

Question 41

racemic mixtures are optically _____

Answer 41

inactive, because for every molecule in a racemic mixture that rotates the plane of polarization in one direction, there is a mirror-image molecule that rotates the plane in the opposite direction.

Question 42

the enantiomeric excess also called the optical purity tells us?

Answer 42

how much of an excess of one enantiomer is in the mixture

Question 43

if we know the number of asymmetric centers we can calculate?

Answer 43

the maximum number of stereoisomers for that compound: a compound can have a maximum of 2^n stereoisomers

Question 44

diastereomers

Answer 44

stereoisomers that are not identical and not mirror images of each other

Question 45

when fischer projections are drawn for stereoisomers with two adjacent asymmetric centers, the enantiomers with the hydrogens on the same side of the carbon chain are called the? , whereas those with the hydrogens on opposite sides are called the?

Answer 45

erythro enantiomers/ threo enantiomers

Question 46

enatiomers have _____ physical properties and chemical properties whereas diastereomers are

Answer 46

identical, different

Question 47

if one of the four groups attached to nitrogen is a lone pair, the enantiomers cannot be separated because they interconvert rapidly at room temperature. this rapid interconversion is called?

Answer 47

amine inversion

Question 48

enantiomers can be separated by a technique called

Answer 48

chromatography

Question 49

chiral probe

Answer 49

something capable of distinguishing between enantiomers.