Ch 5 Stereoisomerism

Question 1

Isomer

Answer 1

compounds that are constructed from the same atoms (same molecular formula) but still differ from each other They have different physical properties

Question 2

constitutional isomer

Answer 2

same molecular formula but different constitution (order of connectivity of atoms)

Question 3

Stereo-isomers

Answer 3

same molecular formula and constitution but different spatial arrangement of atoms

Question 4

super imposable

Answer 4

The ability for an object to be placed over another object, usually in such a way that both will be visible.

Question 5

Chiral

Answer 5

An object (not necessarily a molecule) which is not superposable on its mirror image.

Question 6

chiral center

Answer 6

An atom with three or more attachments, interchanging of two of these attachments leads to another stereoisomer. Most commonly, an sp3 (tetrahedral) carbon bearing four different attachments

Question 7

Enantiomer

Answer 7

when a compound is chiral, it will have one nonsuperimposable mirror image. a chiral compound will have exactly one enantiomer,never more and never less

Question 8

S-configuration

Answer 8

counterclockwise

Question 9

R-configuration

Answer 9

clockwise

Question 10

Designating Configuration using Cahn-Ingold-Prelog

Answer 10

1. Prioritize all four groups connected to the chirality center 2. If necessary, rotate the molecule so that the four priority group is on a dash. 3. determine whether the sequence 1-2-3 is clockwise or counterclockwise

Question 11

Plane polarized light

Answer 11

Light whose electric field oscillates in just one plane.

Question 12

Optically active

Answer 12

A substance which has optical activity

Question 13

Optically inactive

Answer 13

A substance which does not have optical activity

Question 14

Polarimeter

Answer 14

the rotation of plane-polarized light caused by optically active compounds are measured by using a polarimeter.

Question 15

dextorotatory

Answer 15

a compound exhibiting a positive rotation (+)

Question 16

levorotatory

Answer 16

a compound exhibiting a negative rotation (-)

Question 17

optically pure

Answer 17

a solution containing a single enantiomer

Question 18

racemic mixture

Answer 18

a solution containg equal amounts of both enantiomers

Question 19

diastereomers

Answer 19

stereoisomers that are not mirror image of one another. (cis-trans isomers)

Question 20

max number of stereoisomers

Answer 20

2ⁿ where n refers to the number of chirality centers

Question 21

a molecule with an axis of symmetry possesses

Answer 21

rotational symmetry

Question 22

a molecules with a plane of symmetry possesses

Answer 22

reflectional symmetry. Chirality is only dependent on the presence or absence of reflectional symmetry.

Question 23

Any compound that possesses a ____________in any conformation will be achiral.

Answer 23

any compound that possesses a plane of symmetry in any conformation will be achiral.

Question 24

meso compounds

Answer 24

a compound that exhibts reflectional symmetry will be achiral even though it has chirality senters. a meso compound will have fewer than 2ⁿ stereoisomers.