Page 1
? HISTORY :
In 1675, Nicholas Lemery had devided chemical substances into 3 parts.
(i) Mineral substance : which are obtained from minerals. eg. gold, silver, iron etc.
(ii) Vegetable substance : which are obtained from vegetables. eg. sugar, citric acid etc.
(iii) Animal substance : which are obtained from animals. eg. albumin, gilatin etc.
After some time when many of the chemical substance were discovered, it was found that some of them
can be obtained from both vegetables and animals. So this classification was failed. So chemical substance
were then divided into two parts :
(i) Organic compounds : which are obtained from living organism.
(ii) Inorganic compounds : compounds which are obtained from any other sources except living organisms.
VFT(Vital Force Theory) : By Berzelius in 1815. Upto 1815, any organic compound could not be
synthesized in lab. So Berzelius suggested that there is a mysterious force in living organisms which was named
as Vital Force and said that organic compounds cannot be synthesized in lab. This theory was called as VFT.
But in 1828 a German scientist Wholar synthesized an organic compound in lab. Which was 'urea'. So VFT
was failed. Urea was synthesized in lab by heating of Ammonium cyanate (NH
4
CNO).
NH
4
CNO
Rearrangement
?
?? ? ? ? ? ? ?
C
O
NH
2
NH
2
Ammonium cyanate Urea
Organic Compounds : Hydrocarbons and their derivatives are called as organic compounds.
Ex : Why are organic compounds found in larger no.? or Why are they studied as a separate subject ?
S o l . ( i ) Catenation Property : Carbon atom has a property by which it can join with other C–atoms and form
a long chain or a ring of different size and shapes.If covalency of atom is more, then catenation property
is also more.
(i i) Organic compound shows isomerism.
(iii) Exhibits Homologous Series.
( i v) Same Empirical Formulae.
( v ) Polymerisation.
? Characteristics of C-Atoms
(a) Tetra valency : Atomic number of carbon atom is 6 and it have four valency electrons so C-Atom is
tetravalent. It is explained by promotion rule
In ground state (here covalency of carbon is 2)
Available for bond form ation
2s 2p
First excited state (here covalency of carbon is 4)
(b) Tendency to form multiple bonds : Carbon atom forms following type of bonds, such as
C , C
C C
, C C ,
C C C
NOMENCLATURE OF ORGANIC COMPOUNDS
JEEMAIN.GURU
Page 2
? HISTORY :
In 1675, Nicholas Lemery had devided chemical substances into 3 parts.
(i) Mineral substance : which are obtained from minerals. eg. gold, silver, iron etc.
(ii) Vegetable substance : which are obtained from vegetables. eg. sugar, citric acid etc.
(iii) Animal substance : which are obtained from animals. eg. albumin, gilatin etc.
After some time when many of the chemical substance were discovered, it was found that some of them
can be obtained from both vegetables and animals. So this classification was failed. So chemical substance
were then divided into two parts :
(i) Organic compounds : which are obtained from living organism.
(ii) Inorganic compounds : compounds which are obtained from any other sources except living organisms.
VFT(Vital Force Theory) : By Berzelius in 1815. Upto 1815, any organic compound could not be
synthesized in lab. So Berzelius suggested that there is a mysterious force in living organisms which was named
as Vital Force and said that organic compounds cannot be synthesized in lab. This theory was called as VFT.
But in 1828 a German scientist Wholar synthesized an organic compound in lab. Which was 'urea'. So VFT
was failed. Urea was synthesized in lab by heating of Ammonium cyanate (NH
4
CNO).
NH
4
CNO
Rearrangement
?
?? ? ? ? ? ? ?
C
O
NH
2
NH
2
Ammonium cyanate Urea
Organic Compounds : Hydrocarbons and their derivatives are called as organic compounds.
Ex : Why are organic compounds found in larger no.? or Why are they studied as a separate subject ?
S o l . ( i ) Catenation Property : Carbon atom has a property by which it can join with other C–atoms and form
a long chain or a ring of different size and shapes.If covalency of atom is more, then catenation property
is also more.
(i i) Organic compound shows isomerism.
(iii) Exhibits Homologous Series.
( i v) Same Empirical Formulae.
( v ) Polymerisation.
? Characteristics of C-Atoms
(a) Tetra valency : Atomic number of carbon atom is 6 and it have four valency electrons so C-Atom is
tetravalent. It is explained by promotion rule
In ground state (here covalency of carbon is 2)
Available for bond form ation
2s 2p
First excited state (here covalency of carbon is 4)
(b) Tendency to form multiple bonds : Carbon atom forms following type of bonds, such as
C , C
C C
, C C ,
C C C
NOMENCLATURE OF ORGANIC COMPOUNDS
JEEMAIN.GURU
(c) Tetrahedral shape : The four covalent bond are directed
towards the four corners of a regular tetrahedron
C
109°28'
Bond angle 109
0
28' or 109.5'
(d) Catenation : Self linking property of C-atom is known as catenation. It is responsible for the variety
and large number of organic compounds. It may also give rise to open chain and closed chain nature
of compounds. Bond energy for catenation of C is maximum.
Bond energy in Kcal : C — C Si—Si N — N P — P
85 54 39 50
(e) Hybridisation : The orbitals of different shape but almost of equal energies blend up to give the
same number of new orbitals of another shape and of identical energies.
Str uc tu re ? & ? ? bonds Hybridisation Bond angle S h a p e
C 4,0 sp
3
109°28' Tetrahedral
C
3,1 sp
2
120° Planar (Trigonal)
C
2,2 sp 180° Linear
C
2,2 sp 180° Linear
? - (sigma) bonds : The molecular orbital formed by the overlapping of two-s atomic orbtials or one s
and one p atomic orbitals or co-axial overlapping of p-orbitals is called a ? bond.
or
s p
or
p p
Note : (i) Overlapping of hybrid orbitals also give ? bonds. ? bonds are stronger, as they are resulted ed
from the effective axial overlapping.
(ii) More the directional character (p) in covalent bond more is the strength of the bond.
sp
3
- sp
3
> sp
3
- sp
2
> sp
2
- sp
2
> sp - sp
?(Pi) bonds : ? ? bond is formed by the
+
lateral overlapping of two p-atomic
orbitals. It is weaker than ? bond, as there
is only partial overlapping.
JEEMAIN.GURU
Page 3
? HISTORY :
In 1675, Nicholas Lemery had devided chemical substances into 3 parts.
(i) Mineral substance : which are obtained from minerals. eg. gold, silver, iron etc.
(ii) Vegetable substance : which are obtained from vegetables. eg. sugar, citric acid etc.
(iii) Animal substance : which are obtained from animals. eg. albumin, gilatin etc.
After some time when many of the chemical substance were discovered, it was found that some of them
can be obtained from both vegetables and animals. So this classification was failed. So chemical substance
were then divided into two parts :
(i) Organic compounds : which are obtained from living organism.
(ii) Inorganic compounds : compounds which are obtained from any other sources except living organisms.
VFT(Vital Force Theory) : By Berzelius in 1815. Upto 1815, any organic compound could not be
synthesized in lab. So Berzelius suggested that there is a mysterious force in living organisms which was named
as Vital Force and said that organic compounds cannot be synthesized in lab. This theory was called as VFT.
But in 1828 a German scientist Wholar synthesized an organic compound in lab. Which was 'urea'. So VFT
was failed. Urea was synthesized in lab by heating of Ammonium cyanate (NH
4
CNO).
NH
4
CNO
Rearrangement
?
?? ? ? ? ? ? ?
C
O
NH
2
NH
2
Ammonium cyanate Urea
Organic Compounds : Hydrocarbons and their derivatives are called as organic compounds.
Ex : Why are organic compounds found in larger no.? or Why are they studied as a separate subject ?
S o l . ( i ) Catenation Property : Carbon atom has a property by which it can join with other C–atoms and form
a long chain or a ring of different size and shapes.If covalency of atom is more, then catenation property
is also more.
(i i) Organic compound shows isomerism.
(iii) Exhibits Homologous Series.
( i v) Same Empirical Formulae.
( v ) Polymerisation.
? Characteristics of C-Atoms
(a) Tetra valency : Atomic number of carbon atom is 6 and it have four valency electrons so C-Atom is
tetravalent. It is explained by promotion rule
In ground state (here covalency of carbon is 2)
Available for bond form ation
2s 2p
First excited state (here covalency of carbon is 4)
(b) Tendency to form multiple bonds : Carbon atom forms following type of bonds, such as
C , C
C C
, C C ,
C C C
NOMENCLATURE OF ORGANIC COMPOUNDS
JEEMAIN.GURU
(c) Tetrahedral shape : The four covalent bond are directed
towards the four corners of a regular tetrahedron
C
109°28'
Bond angle 109
0
28' or 109.5'
(d) Catenation : Self linking property of C-atom is known as catenation. It is responsible for the variety
and large number of organic compounds. It may also give rise to open chain and closed chain nature
of compounds. Bond energy for catenation of C is maximum.
Bond energy in Kcal : C — C Si—Si N — N P — P
85 54 39 50
(e) Hybridisation : The orbitals of different shape but almost of equal energies blend up to give the
same number of new orbitals of another shape and of identical energies.
Str uc tu re ? & ? ? bonds Hybridisation Bond angle S h a p e
C 4,0 sp
3
109°28' Tetrahedral
C
3,1 sp
2
120° Planar (Trigonal)
C
2,2 sp 180° Linear
C
2,2 sp 180° Linear
? - (sigma) bonds : The molecular orbital formed by the overlapping of two-s atomic orbtials or one s
and one p atomic orbitals or co-axial overlapping of p-orbitals is called a ? bond.
or
s p
or
p p
Note : (i) Overlapping of hybrid orbitals also give ? bonds. ? bonds are stronger, as they are resulted ed
from the effective axial overlapping.
(ii) More the directional character (p) in covalent bond more is the strength of the bond.
sp
3
- sp
3
> sp
3
- sp
2
> sp
2
- sp
2
> sp - sp
?(Pi) bonds : ? ? bond is formed by the
+
lateral overlapping of two p-atomic
orbitals. It is weaker than ? bond, as there
is only partial overlapping.
JEEMAIN.GURU
Ex. 1 ?
sp
?
sp
?
sp
2
?
sp
3
?
sp
2
HC ? C CH CH CH
3
Ex. 2
H H
? ?
C C
H
?
C H
?
C
C
H
?
C
H
?
120°
Flat hexagonal structure due to sp
2
hybridised
C-atom in benzene
? Note :
(A) ? electrons are mobile hence ? bond is more reactive. ? bond is formed by the collateral overlapping ng
of sp
2
orbitals.
(B) sp
2
hybridised orbitals overlap with each other and with s orbitals of six H-atoms forming C–C and
C-H ? bonds.
(C) Six 2p unhybridised orbitals of 6 C-atom in benzene form 3 ? bonds by lateral overlapping with each
other. These six ? electrons are free to move over all the six carbon atoms. Since delocalised electrons
have lower energy than localised.
(D) The relative sizes of hybrid orbital follows the order sp
3
> sp
2
> sp
(E) The electronegativity of hybrid orbitals follows the order sp > sp
2
> sp
3
s – sp
sp– s
3
? Bond
Methane
3
H H
H
H
H
?
?
?
Ethyne
H
?
H sp
sp
sp
sp
?
?
p
z
p
z
p
y
?
p
y
sp
?
?
sp
2
sp
2
sp
2
?
?
?
Ethene
p
H
H
?
sp
2
sp
2
?
p
z
H
H
(Orbital diagram of methane, ethane, ethene and ethyne)
p– sp
3 3
Ethane
s – sp
3
s
H
H
H
H
sp– s
3
H
H
2
z
JEEMAIN.GURU
Page 4
? HISTORY :
In 1675, Nicholas Lemery had devided chemical substances into 3 parts.
(i) Mineral substance : which are obtained from minerals. eg. gold, silver, iron etc.
(ii) Vegetable substance : which are obtained from vegetables. eg. sugar, citric acid etc.
(iii) Animal substance : which are obtained from animals. eg. albumin, gilatin etc.
After some time when many of the chemical substance were discovered, it was found that some of them
can be obtained from both vegetables and animals. So this classification was failed. So chemical substance
were then divided into two parts :
(i) Organic compounds : which are obtained from living organism.
(ii) Inorganic compounds : compounds which are obtained from any other sources except living organisms.
VFT(Vital Force Theory) : By Berzelius in 1815. Upto 1815, any organic compound could not be
synthesized in lab. So Berzelius suggested that there is a mysterious force in living organisms which was named
as Vital Force and said that organic compounds cannot be synthesized in lab. This theory was called as VFT.
But in 1828 a German scientist Wholar synthesized an organic compound in lab. Which was 'urea'. So VFT
was failed. Urea was synthesized in lab by heating of Ammonium cyanate (NH
4
CNO).
NH
4
CNO
Rearrangement
?
?? ? ? ? ? ? ?
C
O
NH
2
NH
2
Ammonium cyanate Urea
Organic Compounds : Hydrocarbons and their derivatives are called as organic compounds.
Ex : Why are organic compounds found in larger no.? or Why are they studied as a separate subject ?
S o l . ( i ) Catenation Property : Carbon atom has a property by which it can join with other C–atoms and form
a long chain or a ring of different size and shapes.If covalency of atom is more, then catenation property
is also more.
(i i) Organic compound shows isomerism.
(iii) Exhibits Homologous Series.
( i v) Same Empirical Formulae.
( v ) Polymerisation.
? Characteristics of C-Atoms
(a) Tetra valency : Atomic number of carbon atom is 6 and it have four valency electrons so C-Atom is
tetravalent. It is explained by promotion rule
In ground state (here covalency of carbon is 2)
Available for bond form ation
2s 2p
First excited state (here covalency of carbon is 4)
(b) Tendency to form multiple bonds : Carbon atom forms following type of bonds, such as
C , C
C C
, C C ,
C C C
NOMENCLATURE OF ORGANIC COMPOUNDS
JEEMAIN.GURU
(c) Tetrahedral shape : The four covalent bond are directed
towards the four corners of a regular tetrahedron
C
109°28'
Bond angle 109
0
28' or 109.5'
(d) Catenation : Self linking property of C-atom is known as catenation. It is responsible for the variety
and large number of organic compounds. It may also give rise to open chain and closed chain nature
of compounds. Bond energy for catenation of C is maximum.
Bond energy in Kcal : C — C Si—Si N — N P — P
85 54 39 50
(e) Hybridisation : The orbitals of different shape but almost of equal energies blend up to give the
same number of new orbitals of another shape and of identical energies.
Str uc tu re ? & ? ? bonds Hybridisation Bond angle S h a p e
C 4,0 sp
3
109°28' Tetrahedral
C
3,1 sp
2
120° Planar (Trigonal)
C
2,2 sp 180° Linear
C
2,2 sp 180° Linear
? - (sigma) bonds : The molecular orbital formed by the overlapping of two-s atomic orbtials or one s
and one p atomic orbitals or co-axial overlapping of p-orbitals is called a ? bond.
or
s p
or
p p
Note : (i) Overlapping of hybrid orbitals also give ? bonds. ? bonds are stronger, as they are resulted ed
from the effective axial overlapping.
(ii) More the directional character (p) in covalent bond more is the strength of the bond.
sp
3
- sp
3
> sp
3
- sp
2
> sp
2
- sp
2
> sp - sp
?(Pi) bonds : ? ? bond is formed by the
+
lateral overlapping of two p-atomic
orbitals. It is weaker than ? bond, as there
is only partial overlapping.
JEEMAIN.GURU
Ex. 1 ?
sp
?
sp
?
sp
2
?
sp
3
?
sp
2
HC ? C CH CH CH
3
Ex. 2
H H
? ?
C C
H
?
C H
?
C
C
H
?
C
H
?
120°
Flat hexagonal structure due to sp
2
hybridised
C-atom in benzene
? Note :
(A) ? electrons are mobile hence ? bond is more reactive. ? bond is formed by the collateral overlapping ng
of sp
2
orbitals.
(B) sp
2
hybridised orbitals overlap with each other and with s orbitals of six H-atoms forming C–C and
C-H ? bonds.
(C) Six 2p unhybridised orbitals of 6 C-atom in benzene form 3 ? bonds by lateral overlapping with each
other. These six ? electrons are free to move over all the six carbon atoms. Since delocalised electrons
have lower energy than localised.
(D) The relative sizes of hybrid orbital follows the order sp
3
> sp
2
> sp
(E) The electronegativity of hybrid orbitals follows the order sp > sp
2
> sp
3
s – sp
sp– s
3
? Bond
Methane
3
H H
H
H
H
?
?
?
Ethyne
H
?
H sp
sp
sp
sp
?
?
p
z
p
z
p
y
?
p
y
sp
?
?
sp
2
sp
2
sp
2
?
?
?
Ethene
p
H
H
?
sp
2
sp
2
?
p
z
H
H
(Orbital diagram of methane, ethane, ethene and ethyne)
p– sp
3 3
Ethane
s – sp
3
s
H
H
H
H
sp– s
3
H
H
2
z
JEEMAIN.GURU
CLASSIFICATION OF ORGANIC COMPOUNDS
O R GANIC CO M P O UND
Open – chain, acyclic
Closed – Chain or
Cyclic compound
or aliphatic compounds
S atu rated
Hom ocyclic
compou nd
Heterocyclic
com pou nd
Alicyclic
com pou nd s
Unsa tu ra ted
Arom a tic
com pou nd s
Non b enzenoid
a lk ene
alkyne
a lkane
CH –CH –CH
3 2 3
Propane
CH –CH= CH
3 2
Propene
HC CH ?
Ethyne
Pentahydropyran
o
Pyridine
N
..
Alicyclic
com pou nd s
Cyclo
hexane
Benzenoid
Cyclo
butene
com pou nd s
*Arom a tic
(Benzene ring
containing compounds)
(Without any Benzene ring
containing compounds)
annulene [18]
Benzene
annulene [18]
Benzene Naphthalene
com pound s
*Arom atic
JEEMAIN.GURU
Page 5
? HISTORY :
In 1675, Nicholas Lemery had devided chemical substances into 3 parts.
(i) Mineral substance : which are obtained from minerals. eg. gold, silver, iron etc.
(ii) Vegetable substance : which are obtained from vegetables. eg. sugar, citric acid etc.
(iii) Animal substance : which are obtained from animals. eg. albumin, gilatin etc.
After some time when many of the chemical substance were discovered, it was found that some of them
can be obtained from both vegetables and animals. So this classification was failed. So chemical substance
were then divided into two parts :
(i) Organic compounds : which are obtained from living organism.
(ii) Inorganic compounds : compounds which are obtained from any other sources except living organisms.
VFT(Vital Force Theory) : By Berzelius in 1815. Upto 1815, any organic compound could not be
synthesized in lab. So Berzelius suggested that there is a mysterious force in living organisms which was named
as Vital Force and said that organic compounds cannot be synthesized in lab. This theory was called as VFT.
But in 1828 a German scientist Wholar synthesized an organic compound in lab. Which was 'urea'. So VFT
was failed. Urea was synthesized in lab by heating of Ammonium cyanate (NH
4
CNO).
NH
4
CNO
Rearrangement
?
?? ? ? ? ? ? ?
C
O
NH
2
NH
2
Ammonium cyanate Urea
Organic Compounds : Hydrocarbons and their derivatives are called as organic compounds.
Ex : Why are organic compounds found in larger no.? or Why are they studied as a separate subject ?
S o l . ( i ) Catenation Property : Carbon atom has a property by which it can join with other C–atoms and form
a long chain or a ring of different size and shapes.If covalency of atom is more, then catenation property
is also more.
(i i) Organic compound shows isomerism.
(iii) Exhibits Homologous Series.
( i v) Same Empirical Formulae.
( v ) Polymerisation.
? Characteristics of C-Atoms
(a) Tetra valency : Atomic number of carbon atom is 6 and it have four valency electrons so C-Atom is
tetravalent. It is explained by promotion rule
In ground state (here covalency of carbon is 2)
Available for bond form ation
2s 2p
First excited state (here covalency of carbon is 4)
(b) Tendency to form multiple bonds : Carbon atom forms following type of bonds, such as
C , C
C C
, C C ,
C C C
NOMENCLATURE OF ORGANIC COMPOUNDS
JEEMAIN.GURU
(c) Tetrahedral shape : The four covalent bond are directed
towards the four corners of a regular tetrahedron
C
109°28'
Bond angle 109
0
28' or 109.5'
(d) Catenation : Self linking property of C-atom is known as catenation. It is responsible for the variety
and large number of organic compounds. It may also give rise to open chain and closed chain nature
of compounds. Bond energy for catenation of C is maximum.
Bond energy in Kcal : C — C Si—Si N — N P — P
85 54 39 50
(e) Hybridisation : The orbitals of different shape but almost of equal energies blend up to give the
same number of new orbitals of another shape and of identical energies.
Str uc tu re ? & ? ? bonds Hybridisation Bond angle S h a p e
C 4,0 sp
3
109°28' Tetrahedral
C
3,1 sp
2
120° Planar (Trigonal)
C
2,2 sp 180° Linear
C
2,2 sp 180° Linear
? - (sigma) bonds : The molecular orbital formed by the overlapping of two-s atomic orbtials or one s
and one p atomic orbitals or co-axial overlapping of p-orbitals is called a ? bond.
or
s p
or
p p
Note : (i) Overlapping of hybrid orbitals also give ? bonds. ? bonds are stronger, as they are resulted ed
from the effective axial overlapping.
(ii) More the directional character (p) in covalent bond more is the strength of the bond.
sp
3
- sp
3
> sp
3
- sp
2
> sp
2
- sp
2
> sp - sp
?(Pi) bonds : ? ? bond is formed by the
+
lateral overlapping of two p-atomic
orbitals. It is weaker than ? bond, as there
is only partial overlapping.
JEEMAIN.GURU
Ex. 1 ?
sp
?
sp
?
sp
2
?
sp
3
?
sp
2
HC ? C CH CH CH
3
Ex. 2
H H
? ?
C C
H
?
C H
?
C
C
H
?
C
H
?
120°
Flat hexagonal structure due to sp
2
hybridised
C-atom in benzene
? Note :
(A) ? electrons are mobile hence ? bond is more reactive. ? bond is formed by the collateral overlapping ng
of sp
2
orbitals.
(B) sp
2
hybridised orbitals overlap with each other and with s orbitals of six H-atoms forming C–C and
C-H ? bonds.
(C) Six 2p unhybridised orbitals of 6 C-atom in benzene form 3 ? bonds by lateral overlapping with each
other. These six ? electrons are free to move over all the six carbon atoms. Since delocalised electrons
have lower energy than localised.
(D) The relative sizes of hybrid orbital follows the order sp
3
> sp
2
> sp
(E) The electronegativity of hybrid orbitals follows the order sp > sp
2
> sp
3
s – sp
sp– s
3
? Bond
Methane
3
H H
H
H
H
?
?
?
Ethyne
H
?
H sp
sp
sp
sp
?
?
p
z
p
z
p
y
?
p
y
sp
?
?
sp
2
sp
2
sp
2
?
?
?
Ethene
p
H
H
?
sp
2
sp
2
?
p
z
H
H
(Orbital diagram of methane, ethane, ethene and ethyne)
p– sp
3 3
Ethane
s – sp
3
s
H
H
H
H
sp– s
3
H
H
2
z
JEEMAIN.GURU
CLASSIFICATION OF ORGANIC COMPOUNDS
O R GANIC CO M P O UND
Open – chain, acyclic
Closed – Chain or
Cyclic compound
or aliphatic compounds
S atu rated
Hom ocyclic
compou nd
Heterocyclic
com pou nd
Alicyclic
com pou nd s
Unsa tu ra ted
Arom a tic
com pou nd s
Non b enzenoid
a lk ene
alkyne
a lkane
CH –CH –CH
3 2 3
Propane
CH –CH= CH
3 2
Propene
HC CH ?
Ethyne
Pentahydropyran
o
Pyridine
N
..
Alicyclic
com pou nd s
Cyclo
hexane
Benzenoid
Cyclo
butene
com pou nd s
*Arom a tic
(Benzene ring
containing compounds)
(Without any Benzene ring
containing compounds)
annulene [18]
Benzene
annulene [18]
Benzene Naphthalene
com pound s
*Arom atic
JEEMAIN.GURU
? Aliphatic or Open chain compounds :
Those compounds in which first & last carbon atoms are not connected with each other. Branched or unbranched
chains are possible in these compounds.
For example :
CH–CH–CH–CH
3 2 2 3
,
CH–CH– CH –CH
3 2 3
CH
3
,
CH–C–CH
3 3
CH
3
CH
3
(Unbranched) (Branched)
There are two varieties in these compounds -
? Saturated Hydrocarbons :
(a) In such type, adjacent carbon are attached with single bonds.
Example - CH
3
–CH
2
–CH
3
(b) General formula of these compounds are C
n
H
2n+2
(c) These are also called as paraffins (Parum + Affins i.e. little reactivity) because these are less reactive
due to absence of ?-bonds.
? Unsaturated Hydrocarbons :
(a) There will be a double bond or a triple bond between any two carbon atoms,
CH
2
= CH – CH
3
Propene
CH ? ? C – CH
3
Propyne
(b) General formula is C
n
H
2n
or C
n
H
2n–2
(c) These are also called as olefins because they reacts with halogens to form oily substances olefins
(Oleum + fines i.e. Oil forming).
(d) Due to presence of ? bonds these are more reactive.
? Closed chain compounds :
In these compounds first & last carbon are attached with each other.
Example.
CH
2
CH
2
CH
2
cyclopropane.
? Homocyclic compounds :
These are the compounds in which the complete ring is formed by carbon atoms only. These are also of
two types
( A ) Alicyclic compounds : These are the compounds having the properties like aliphatic compounds.
These may be saturated or unsaturated like aliphatic compounds.
cyclopropane cyclopropene cyclobutene
( B ) Aromatic compounds : Conditions for a compound to be aromatic -
(i) Compound should be cyclic.
(ii) Compound should be planar. (All carbon in ring should be sp
2
hybridised)
JEEMAIN.GURU
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