1. Carbon exists in Earth's crust and atmosphere and forms millions of compounds due to its ability to catenate and be tetravalent. Organic chemistry studies carbon compounds except oxides, carbonates, and bicarbonates.
2. Berzelius proposed that organic compounds could only be synthesized in living organisms, but Wohler synthesized urea in the laboratory in 1828, disproving this vital force theory.
3. Carbon forms covalent bonds by sharing electrons in stable octet configurations, allowing it to form diverse chains, rings, and functional groups that exhibit properties ranging from nonpolar to ionic.
2. ● Earth’s crust has 0.02% of carbon in the form of
minerals (like carbonates, hydrogen carbonates,
coal and petroleum)
● Atmosphere has 0.03% of carbon dioxide.
● The branch of chemistry that deals with the study
of carbon and its compounds ( except for oxides
of carbon, carbonate and bicarbonate) is known
as Organic Chemistry.
3. Properties of carbon compounds
● Most carbon compounds are poor conductors
of electricity.
● Bonding in these compounds does not give
rise to any ions.
● Force of attraction between the molecules is
not very strong.
4. Vital force theory
● In 1815 AD, a Swedish chemist J.J. Berzelius put forward vital force theory to
explain the origin of organic compound.
● According to this theory, organic compound are formed and synthesized only
within living species( plants and animals ). The word ‘vital’ is derives from
Latin term ‘vita’ which means life. This theory does not account synthesis of
organic compounds in laboratory.
● However, in 1828 AD, a German chemist Friedrich Wohler synthesized
organic compound ‘urea’ from simple inorganic compound ammonium
cyanate. This theory defied the vital force theory.
5. Bonding in Carbon compounds
● Carbon could gain four electrons to form C4- anion. But it
will be difficult for the nucleus with six protons to hold on
to the ten electrons,ie, the extra four electrons.
● Carbon could lose four electrons and form C4+ cation. But
it requires large amount of Ionisation energy to remove
four electrons leaving behind a carbon with six protons in
its nucleus holding on to just two electrons
6. Covalent Bonding
A chemical bond formed by sharing of valence shell electrons so that each atoms
acquires the nearest noble gas configuration is known as covalent bond and
compounds formed by sharing of electrons are known as covalent compounds.
Eg: Formation of methane
Bonding in hydrogen Bonding in oxygen Bonding in nitrogen
Single bond Double bond Triple bond
7. Electron dot structure for methane
● Methane is widely used as a fuel
● Major component of biogas and CNG
10. Characteristic of covalently bonded compounds
● Covalently bonded molecules have strong bonds within
the molecule but intermolecular forces are small. This give
rise to low MP and BP.
● Since electrons are shared between atoms, no charged
particles are formed. Such covalent compounds are
generally poor conductors of electricity.
● Covalent compounds are generally insoluble in water.
11. Allotrope
● Property of some chemical elements to exist in two or more different forms, in
the same physical state, is called allotropy and each state is known as an
allotrope. Eg: Carbon - Graphite, Diamond, Buckminsterfullerene (C-60).
● They have different physical properties but have same chemical properties.
Graphite Diamond Buckminsterfullerene (C-60)
12. Versatile nature of Carbon
● More than 3 million compounds of carbon are
known to the chemist.
● Carbon form enormous number of compounds
due to
- Catenation
- Tetravalency
13. 1. Catenation
● Carbon has unique ability to form bonds with other atoms
of carbon.
● These compounds can be long chained, branched or
rings.
● Carbon atoms may be linked by single, double or triple
bonds.
● Carbon compounds with only single bonds between
carbon atoms are called saturated compounds.
● Carbon compounds with double or triple bond between
carbon atoms are called unsaturated compounds.
14. 2. Tetravalency
● Carbon has four valence with which it forms bond with
other atoms of carbon or atoms of some monovalent
element.
● Compounds of carbon are formed with Oxygen, Nitrogen,
Hydrogen, Sulphur, Chlorine and many other elements
giving rise to compounds with specific properties, which
depend on elements other than carbon present in the
molecule.
15. Other reasons
● Bonds formed between carbon and atoms of other
elements are exceptionally strong and stable.
● Strong bonds are formed due to the small size of the
carbon, which enables the nucleus to hold on to the
shared pair of electrons strongly.
16. Hydrocarbons
● Compounds of carbon having only carbon and hydrogen
are called hydrocarbons.
● Oil reserves in sedimentary rocks are the source of
hydrocarbons for the energy, transport and petrochemical
industries.
● Economically important hydrocarbons include fossil fuels
such as coal, petroleum and natural gas, and its
derivatives such as plastics, paraffin, waxes, solvents and
oils.
18. Saturated Hydrocarbons - Alkanes
● Hydrocarbons in which the carbon atoms are
connected by only single bond is called a
saturated hydrocarbon or alkanes
● The names of all saturated hydrocarbons ends
with ‘ane’
● The general formula of saturated hydrocarbons
or alkanes is CnH2n+2 , where n represents the
number of carbon atoms in the molecule.
19. Names of the first ten members of the alkane family and their structures
20. Unsaturated Hydrocarbons
● A hydrocarbon in which the two carbon atoms are
connected by a double or a triple bond is called an
unsaturated hydrocarbon.
● Unsaturated hydrocarbons are of two types
a. Alkenes
b. Alkynes
21. Alkenes
● The unsaturated hydrocarbons in which the two
carbon atoms are connected by a double bond is
called an alkene.
● The general formula alkenes are CnH2n , where n
represents the number of carbon atoms in the
molecule.
● There is no alkene with one carbon atom.
22.
23.
24. Isomerism
● The organic compounds having same molecular formula but different
structures are known as isomers. This phenomenon is known as isomerism.
● Isomers of butane
29. Characteristics of isomers
● Same molecular formula
● Different structural formula
● All the physical and chemical properties of isomers of a
compound differ from each other.
30. Alkynes
● An unsaturated hydrocarbon in which two carbon atoms
are connected by a triple bond is called an alkyne.
● They are represented by the general formula CnH2n-2.
● Alkenes and alkynes are chemically more reactive than
alkanes.
● Arrangement in terms of decreasing order of stability,
Alkanes > Alkenes > Alkynes.
31.
32. Alkyl Group (CnH2n+1)
● The group formed by the removal of one hydrogen atom
from an alkane molecule is called an alkyl group.
● The free line indicates that one valency is free in the alkyl
group.
33. Cyclic Hydrocarbons
● The hydrocarbons in which the carbon atoms are
arranged in the form of a ring are called cyclic
hydrocarbons.
● It can be saturated or unsaturated.
● Saturated hydrocarbons are called cyclo alkanes
● Cyclo alkanes are represented by the general formula
CnH2n
● The first member starts with 3 carbon atoms.
35. Aromatic hydrocarbons - Arenes
Arenes are compounds contains one or more benzene ring as a part of their
structure. The double bonds are delocalized.
They are called aromatic because of their fragrant smell.
36. Simplest aromatic hydrocarbon - Benzene
● Benzene is an unsaturated cyclic hydrocarbon.
● It has 3 (C-C)
● 3 (C=C)
● 6 (C-H)
37.
38. Homologous Series
● A series of closely related members with same functional
group, having similar structure and chemical properties, in
which the successive members differ by a >CH2 group.
● The various organic compounds of the homologous series
are called homologue.
41. Functional Groups
● The hydrogen atom in a hydrocarbon
can be replaced by a heteroatom.
● These heteroatoms and groups
containing these confer specific
properties to the compounds,
regardless of the length and nature of
the carbon chain and hence are
called functional groups.
● It is a group that determines the chemical nature of an
organic compound.
46. Chemical properties of carbon compounds
1. Combustion - Carbon burns in oxygen to give carbon
dioxide along with the release of heat and light.
47. Test for unsaturation - 1
● Saturated hydrocarbons will give a clean flame when
introduced into the flame.
● Unsaturated hydrocarbons will give a yellow flame with a
lots of black smoke, because the percentage of carbon is
comparatively higher than alkanes, which does not burn
completely in air.
● Limiting the supply of air results in incomplete combustion
of even unsaturated hydrocarbons giving a sooty flame.
● Flame is only produced when gaseous substance burns.
48. Important points to remember.
● If a mixture of acetylene (ethyne) and pure oxygen is
burned, acetylene burns completely producing a blue
flame. The oxygen acetylene flame (oxyacetylene flame)
is extremely hot and produces very high temperature
which is used for welding metals.
● LPG (ethane + Propane + Butane(main component)) is an
excellent fuel because the burns in air to produce a lot of
heat energy.
49. Oxidation reaction
Oxidation is the reaction in which carbon compounds take up
oxygen in presence of oxidising agents to give another
carbon compound.
Eg : Alcohols are oxidised to acids in the presence of alkaline
potassium permanganate or acidified potassium dichromate
(Oxidising agents).
50. Addition reaction ( Catalytic hydrogenation)
● Unsaturated hydrocarbons add hydrogen in presence of Ni,Pt or Pd catalyst
to produce saturated hydrocarbons.
● It is commonly used in the hydrogenation of vegetable oils using Ni catalyst.
● Vegetable oils are generally long unsaturated carbon chains while animal fats
have saturated carbon chain.
51. Test for unsaturation - 2
Add few drops of bromine water to unsaturated compound. If
it gets decolourised it is an unsaturated compound.
52. Substitution reaction
● Saturated hydrocarbons are fairly unreactive and inert in the presence of
most reagents.
● In a substitution reaction, an atom or a group of atoms present in a compound
is replaced by another atom or a group without the compound undergoing any
change in its structure. If substitution takes place by using halogens it is
called halogenation reaction.
● Eg: In presence of sunlight chlorine is added to hydrocarbons, H is
substituted by Cl and methyl chloride is formed. If the substitution takes place
by chlorine, it is also called chlorination.
54. Ethanol (C2H5OH) - Ethyl alcohol
● Colourless liquid with a pleasant smell and a burning taste
.It is an active ingredient in all alcoholic drinks.
● It is volatile and has low boiling point (78oC)
● Highly soluble in water.
● It is neutral and has no effect on any litmus solution.
● Ethanol containing 5% water is called rectified spirit
(Commercial alcohol)
● 100% pure ethanol is called absolute alcohol.
● It is a good solvent and hence used in many medicines
like tincture of iodine, cough syrups and many tonics.
55. Chemical properties of ethanol
● Reaction with sodium - Ethanol reacts with sodium to
produce sodium ethoxide and hydrogen gas.
56.
57. Reaction to form unsaturated hydrocarbons
Heating ethanol at 443K with excess concentrated sulphuric
acid results in the dehydration of ethanol to give ethene.
Conc. Sulphuric acid is used as a dehydrating agent which
removes water from ethanol.
59. Alcohol as fuel
● Sugarcane juice is used to prepare molasses which is
fermented to give alcohol (ethanol).
● Some countries now use alcohol as an additive in petrol
since it is a cleaner fuel which gives rise to only carbon
dioxide and water on burning in sufficient air (oxygen).
60. Denatured alcohol or methylated spirit
Denatured alcohol, also called methylated spirits or
denatured rectified spirit, is ethanol that has additives to
make it poisonous, bad tasting, foul smelling or nauseating,
to discourage recreational consumption. In some cases it is
also dyed.
61. Ethanoic acid - CH3-COOH (Acetic acid)
● Belongs to the family of carboxylic acid. It is a weak acid.
That is it do not completely ionise in solution.
● 5-8% solution of acetic acid in water is called vinegar
which is widely used as preservative in pickles.
● The melting point of pure ethanoic acid is 290K and often
freezes during winter in cold climates. Hence called
Glacial acetic acid.
62. Reactions of ethanoic acid
Esterification reaction - Ethanoic acid
reacts with ethanol in presence of acid
catalyst to form esters.
Ethyl ethanoate
63. ● Esters are sweet smelling substances.
● They are used in making perfumes and as flavouring
agents.
● On treating with NaOH, esters are converted back to
alcohol and sodium salt of carboxylic acid. This reaction is
called Saponification reaction because it is used in the
preparation of soap.
64. 2. Reaction with a base.
● Ethanoic acid reacts with a base like NaOH to give a
salt(Sodium ethanoate or sodium acetate) and water.
65. 3. Reaction with Carbonates and Bicarbonates
Ethanoic acid reacts with carbonates and hydrogen
carbonates to give rise to salt, water and carbon dioxide. The
salt produced is sodium acetate.
71. Detergents
● Hardness of water is due to the presence of bicarbonates, chlorides or
sulphates of Ca2+ and Mg2+ ions.
● Soap reacts with hard water and produces insoluble precipitates called Scum.
● Detergents are generally ammonium or sulphonate salts of long chain
carboxylic acids.
● The charged ends of these compounds do not form insoluble precipitates with
the calcium and magnesium ions in hard water. Thus, they remain effective in
hard water.
● Detergents are usually used to make shampoos and products for cleaning
clothes.
