Alkenes

Question 1

why are alkenes highly reactive

Answer 1

the double bond is an area of high electron density

Question 2

what does the double bond result from

Answer 2

the overlap of the spare unbonded singly filled p orbitals present on each carbon atom in the bond

Question 3

what does the overlap of the p orbitals produce

Answer 3

a cloud of electron density above and below the molecule forming a pi bond

Question 4

what’s the rotation like around the c=c bond

Answer 4

there’s no free rotation around the c=c bond

Question 5

what shape is the c=c bond and what’s the bond angle

Answer 5

planar

120°

Question 6

what are the 2 types of isomers

Answer 6

structural

and

stereoisomers

Question 7

give the definition for stereoisomers

Answer 7

same structural formula but different arrangment in space

Question 8

give the 2 forms of stereoisomers

Answer 8

e-z isomerism (geometric)

optical isomerism

Question 9

give 2 reasons for geometric isomerism to exist

Answer 9

• the restricted rotation about the carbon to carbon double bond
• 2 different atoms/groups attached to each carbon in the double bond

Question 10

what is E isomerism

Answer 10

it means the 2 highest priority groups are on OPPOSITE sides of the double bond

Question 11

what is Z isomerism

Answer 11

the 2 highest priority groups are on the SAME side of the double bind

Question 12

how do we determine priority of groups for e-z isomerism

Answer 12

by looking at atomic number

Question 13

the double bond is an area of high electron density therefore what is it attacked by

Answer 13

electrophiles

Question 14

the double bond is an area of high electron density therefore what is it attacked by

Answer 14

electrophile

Question 15

what are electrophiles

Answer 15

electron pair acceptors

Question 16

learn all of electrophillic addition in notes bc it’s too much for flashcards

Answer 16

now

Question 17

how many products are formed with symmetrical alkenes

Answer 17

1

Question 18

how many products formed with unsymmetrical alkenes in electrophillic addition

Answer 18

2

a major product
a minor product

Question 19

what’s the major product

Answer 19

forms the most stable carbocation

Question 20

which carbocation is most stable: primary or tertiary

Answer 20

tertiary

Question 21

what do the alkyl groups do to the carbonation

Answer 21

alkyl groups like methyl and ethyl groups are electron donating through the positive inductive effect.

the alkyl groups push electron density towards the positively charged carbon atom, helping to stabilise the carbocation

therefore more alkyl groups, more stability

Question 22

what do the 2 carbocation intermediates lead to?

Answer 22

they lead to 2 products being formed ( a major and minor product)

Question 23

are the products from unsymmetrical alkenes in a 50/50 ratio

Answer 23

no , the most stable carbocation will form more product

Question 24

what’s the uses for poly(ethene)

Answer 24

plastic bags

washing up bowls

Question 25

what’s the uses for poly(propene)

Answer 25

rope