14.6 Stereoisomerism

Question 1

What are stereoisomers

Answer 1

These are compounds whose molecules have the same atoms bonded to each other in the same way but with different arrangement of atoms in space so that molecules cannot be superimposed on each other

Question 2

What are the two types of stereisomerism

Answer 2

1.geometrical(cis/trans) isomerism
2. Optical isomerism

Question 3

What is one of the differences between C-C bond and C=C bond

Answer 3

There is no free rotation about C=C bond because of the presence of a pi bond

Question 4

What is geometrical isomerism

Answer 4

Displayed by unsaturated or ring compounds with the same molecular formula and order of atoms but different shapes.

Question 5

What is added in front of the name of geometrical isomer of a molecule

Answer 5

Cis and Trans

Question 6

Why do the two stereoisomers with geometrical isomerism gave different physical properties

Answer 6

Because they have different arrangements of atoms in space so they are different compounds

Question 7

Stereoisomers in geometrical isometric can also have different chemical properties such as

Answer 7

Different rates if reactions

Question 8

Why is geometrical isomerism also possible in substituted cyclic compounds

Answer 8

Because of the limited rotation about C-C atoms that make up the rings

Question 9

Why is geometrical isomerism also possible in substituted cyclic compounds

Answer 9

Because of the limited rotation about C-C atoms that make up the rings

Question 10

We usually show cis and trans atoms using

Answer 10

A combination of skeletal and 3d formulae

Question 11

What is optical isomerism

Answer 11

If a molecule that contains a carbon atom that is bonded to four different atoms or groups of atoms can form two optical isomers

Question 12

What is the carbon atom with four different atoms or groups of atoms attached called. What is it referred as?

Answer 12

Chiral centre; ‘assymetric)

Question 13

The two different optical isomers are called

Answer 13

Enantiomers

Question 14

What are enantiomers

Answer 14

A pair of optically active molecules whose mirror image cannot be superimposed

Question 15

Normal light is unpolarised, what does this mean

Answer 15

It can be thought of as fluctuating magnetic or electric field, vibrating at right angles to each other in every direction possible.

Question 16

How is polarized light formed

Answer 16

By passing the unpolarised light through a polariser

Question 17

What is the feature of polarised light

Answer 17

It vibrates in only one plane

Question 18

What effect does a pair of optical isomers have on polarised light

Answer 18

A pair of optical isomers will rotate the pair of polarised light in equal amounts but in opposite directions. (Clockwise and anti-clockwise)

Question 19

If an organic molecule has two chiral centres

Answer 19

Then there are four possible optical isomers

Question 20

Substituted cyclic molecules can also have

Answer 20

Chiral centres

Question 21

Why do symmetrical substituted cyclic molecules will not have a chiral centre

Answer 21

Starting from carbon atom bonded to the group substituted into the ring or bonded to the group, you will find two identical groups going around the ring in both clockwise and anti-clockwise direction. Therefore no carbon atom has four different groups attached to it.