mechanism of alkenes

Question 1

what are alkenes

Answer 1

they are unsaturated hydrocarbons with at least one double carbon carbon bond

Question 2

smallest alkene

Answer 2

ethene

Question 3

structure of alkenes

Answer 3

120 angle

trigonal planar

Question 4

Why a double bond cannot rotate

Answer 4

The p orbital contains a electron in each carbon. These oribitals overlaps to form a pi bond. The pi bond is electron dense cloud above and below the bond. Thise presence causes restricted rotation.

Question 5

types of isomerism in alkenes

Answer 5

geometric

positional

Question 6

Position isomers

Answer 6

These are isomers with the double bond in different positions, between carbons in carbon chain.

Question 7

Geometrical isomers

Answer 7

type of stereoisomerism.

bonds are arranged differently in space

e and z

Question 8

alkenes are not polar because

Answer 8

the electronegavity of hydrogen and carbon is similar.

Question 9

do alkenes have van der waal forces

Answer 9

very weak yes

Question 10

do alkenes dissolve in water

Answer 10

no. hydrogen bonds between water molecules are stronger than the alkenes wan der waal forces

Question 11

what is an electrophile

Answer 11

species that accept electrons. they are usually partially positive or cation

Question 12

steps of electrophillic addition

Answer 12

I The electrophile is attracted to the double bond.

2 Elcctrophiles accept a pair of electrons
from the double bond.

3 A carbocation is formed.

4 A negatively charged ion forms a bond with the carbocation.

Question 13

characteristic of carbocation

Answer 13

The electrophilc may be a positively

charged ion or have a positively charged area.

Question 14

condition for electrophillic addition with Br

Answer 14

aqeous

reagant Br2

Question 15

condition for electrophillic addition in water

Answer 15

h20 with strong acid

Question 16

condition for electrophilic addition with HBR

Answer 16

HBR as reagant

Question 17

condition for electrophillic addition with H2S04

Answer 17

H2S04 as reagent.

concentrated H2S04 with cold room temperature

Question 18

what conditions do primary haloalkanes prefer

Answer 18

subsitition

Question 19

what conditions do tertiary haloalkanes prefer

Answer 19

elimination

Question 20

what is the positive inductive effect

Answer 20

the ability to release electrons

Question 21

what does the ability to release electrons do to effect the stability of carbocations.

Answer 21

This electron-releasing effect tends to stabilise the positive charge of carbocation. The more alkyl groups there are attached to the positively charged carbon atom, the more stable the carbocation.

Question 22

how do br2 becomes polar

Answer 22

as br2 gets closer to the c=c bonds the electron dense clouds repel the electrons in one of the br.

This induces a dipole.