2.8 characteristic of organic reactions

Question 1

reaction mechanism

meaning

Answer 1

the detailed description of how bonds are broken and formed as reactant is converted to product

Question 2

curly arrows

meaning

Answer 2

it shows a sequence of steps, showing the path taken by electrons in a reaction

full: movement of 2 electrons
half: movement of 1 electron

Question 3

breaking covalent bond

known as?

Answer 3

bond fission

Question 4

how many types of bond fission

Answer 4

2 types

homolytic fission: splitting of a covalent bond where one electron goes to each atom. thus, radicals are formed

heterolytic fission: splitting of a covalent bond where one of the atom retains both the bonding electrons. thus, ions are formed

ions formed: electrophiles( electron pair acceptor ), nucleophiles( electron pair donor)

Question 5

alkyl molecules carries a + charge is called as carbocation

carbocations are unstable due to elctron deficient and only has three covalent bond

shape is trigonal planar and bond angle of 120

name three types of carbocation

Answer 5

primary : least stable

secondary:
tertiary: most stable

Question 6

type of chemical species: can be atom, molecule, ion or part of molecule

name the three

Answer 6

free radicals

electrophiles

nucleophiles

Question 7

free radical

meaning and example

Answer 7

a chemical species with an unpaired electron

cl, ch3, clO*

Question 8

electrophile

meaning and example

Answer 8

a chemical species that accepts a lone pair of electtons to form dative covalent bond

ions: H+
slightly + atoms in molecule: H-Br, the slightly + H
neutral molecule that can be polarised: Br—Br

Question 9

nucleophile

meaning and example

Answer 9

a chemical species that can donate a lone pair of electrons to form a dative covalent bond

ions: Cl-, OH-, CN-
neutral molecules containing O or N: H2O. NH3

Question 10

dot and cross diagram for chlorine

molecule
atom
free radical
electrophile
nucleophile

Answer 10

refer to notes pg 3

Question 11

identify the chemical species of nitrogen monoxide

Answer 11

free radical

has unpaired electron

Question 12

H2, H+, OH-

which is a nucleophile

Answer 12

OH-

it is attracted to slightly + C
donate a lone pair of electrons

Question 13

H2, H+, OH-

which is a electrophile

Answer 13

H+

it has one less electron in its outer shell
accept a lone pair of electrons to form dative covalent bond

Question 14

3 types of the main organic reactions

and reagent used

Answer 14

nucleophilic: nucleophiles
elctrophilic: electrophiles

free radical: free radial

Question 15

what happens when the 3 organic reactions are over

Answer 15

addition

substitution

elimination

redox

hydrolysis

Question 16

addition reaction

meaning
example of reactions

Answer 16

refer notes

Question 17

substitution reaction

meaning
example of reactions

Answer 17

refer notes

Question 18

elimination reaction

meaning
example of reactions

Answer 18

refer notes

Question 19

oxidation reaction

meaning
example of reactions

Answer 19

refer notes

Question 20

reduction reaction

meaning
example of reactions

Answer 20

refer notes

Question 21

hydrolysis reaction

meaning
example of reactions

Answer 21

refer notes

Question 22

polymerisation reaction

meaning
example of reactions

Answer 22

refer notes

Question 23

slightly + C —-CL in halogenoalkanes

polarity
reagent
type of reaction

Answer 23

polar

nucleophile

nucleophilic reaction

Question 24

C–C in alkanes

polarity
reagent
type of reaction

Answer 24

non polar

free radical

free radical substitution

Question 25

C = C in alkenes

polarity
reagent
type of reaction

Answer 25

non polar ( electron riched )

electrophile

electrophile addition

Question 26

why primary carbocation is the least stable?

Answer 26

Alkyl groups do precisely the opposite and, rather than draw electrons towards themselves, tend to “push” electrons away

The arrow shows the electrons being “pushed” away from the CH3 group. The plus sign on the left-hand end of it shows that the CH3 group is becoming positive. The symbols + and - simply reinforce that idea.

You will see that the electron pushing effect of the CH3 group is placing more and more negative charge on the positive carbon as you go from primary to secondary to tertiary carbocations. The effect of this, of course, is to cut down that positive charge.

At the same time, the region around the various CH3 groups is becoming somewhat positive. The net effect, then, is that the positive charge is being spread out over more and more atoms as you go from primary to secondary to tertiary ions.

The more you can spread the charge around, the more stable the ion becomes.

This means that it is going to take more energy to make a primary carbocation than a secondary one