Revision Notes for Board Exams | Carbon and it’s Compounds

Carbon and Compounds is one of the most important chapter for 10th class Chemistry board examination! Here, is a simplified version of this chapter to help you with your board preparation.

Introduction :

• The element carbon is non-metal. Its symbol is C.

• Carbon is versatile element present in earth crust in form of mineral is
0.02% and atmosphere as CO2 is 0.03%.

• All the living things, plants and animals are made up of carbon based
compounds.

Carbon always form covalent bonds :
The atomic number of carbon is 6.
Electronic configuration :
 K           L

 2           4          C(6)

How carbon attain noble gas configuration ?

(i) Carbon is tetravalent, it does not form ionic bond by either losing four
electrons (C4+) or by gaining four electrons (C4−). It is difficult to hold
four extra electron and would require large amount of energy to remove
four electrons. So, carbon can form bond by sharing of its electrons with
the electrons of other carbon atom or with other element and attain noble
gas configuration.
(ii) The atoms of other elements like hydrogen, oxygen and nitrogen,
chlorine also form bonds by sharing of electrons.
(iii) The bond formed by sharing of electrons between same or different
atoms is covalent bond.

Physical Properties of Covalent Compounds
(a) Covalent compounds have low melting and boiling points as they have
weak intermolecular force.
(b) They are generally poor conductor of electricity as electrons are shared
between atoms and no charged particles are formed.

 

 

Versatile Nature of Carbon

The two characteristic properties of carbon element which lead to the forma-
tion of large number of compounds :

(i) Catenation : Carbon can link with carbon atoms by means of covalent
bonds to form long chains, branched chains and closed ring. Compound
Carbon atoms may be linked by single, double or triple bonds.
(ii) Tetravalency : Carbon has 4 valence electrons. Carbon can bond with
four carbon atoms, monovalent atoms, oxygen, nitrogen and sulphur.

 

Saturated and Unsaturated Carbon Compounds
Compounds made up of hydrogen and carbon are called hydrocarbon.

 

 

                                                                          

These three above compounds has same molecular formula but different
structures are called structural isomers and phenomenon is structural isomerism.

Functional Groups
• In hydrocarbon chain, one or more hydrogen atom is replaced by other
atoms in accordance with their valancies. These are heteroatom.
• These heteroatom or group of atoms which make carbon compound
reactive and decides its properties are called functional groups.

 

 

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Homologous Series

It is series of compounds in which the some functional group substitutes for
the hydrogen in a carbon chain.
E.g., Alcohols – CH3OH, C2H5OH, C3H7OH, C4H9OH
• Have same general formula.
• Any two homologues differ by – CH2 group and difference in molecular
mass is 14μ.
• Have same chemical properties but show gradual change in physical
properties.

Nomenclature of Carbon Compounds

(i) Identify the number of carbon atoms in compounds.
(ii) Functional group is indicated by suffix or prefix.

 

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Chemical Properties of Carbon Compounds
(a) Combustion

• Carbon and its compounds are used as fuels because they burn in air
releasing lot of heat energy.
• Saturated hydrocarbon generally burn in air with blue and non-sooty
flame.
• Unsaturated hydrocarbon burns in air with yellow sooty flame because
percentage of carbon is higher than saturated hydrocarbon which does
not get completely oxidized in air.
(b) Oxidation
Alcohols can be converted to carboxylic acid in presence of oxidizing agent
alkaline KMnO4 (potassium permangnate) or acidic potassium dichromate.                                                                                                           

Unsaturated hydrocarbon add hydrogen in the presence of catalyst palladium
or nickel. Vegetable oils are converted into vegetable ghee using this process. It
is also called hydrogenation of veetable oils.
(d) Substitution Reaction :

 

Important Carbon Compounds : Ethanol and Ethanoic acid
Physical Properties of Ethanol
• Colorless, pleasant smell and burning taste.                                                                                                                                                                             • Soluble in water.
• Volatile liquid with low boiling point of 351 K.
• Neutral compound.
Chemical Properties
(i) Reaction with Sodium :
2Na + CH3CH2OH → 2CH3CH2ONa+ + H2
(Sodium ethoxide)
This reaction is used as a test for ethanol by evolution of H2 gas (Burn with
pop sound)

(ii) Dehydration

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Physical Properties of Ethanoic acid
• Colourless liquid having sour taste and have smell of vinegar.
• Boiling point is 391 K.
• When pure CH3COOH is freezed, it forms colourless ice like solid. So it
is called glacial acetic acid.
Chemical Properties
(i) Esterification :

(ii) Reaction with base :
NaOH + CH3COOH → CH3COONa + H2O
(Sod. acetate)                                                                                                                                                                                       (iii) Reaction with (iii)Reaction with carbonates and hydrogen carbonates :
2CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2
CH3COOH + NaHCO3 → CH3COONa + H2O + CO2
(Sod. acetate)

 

 

Soaps and Detergents
• Soap is sodium or potassium salt of long chain carboxylic acid. E.g.,
C17H35COONa+
• Soaps are effective only in soft water.
• Detergents are ammonium or sulphonate salt of long chain of carboxylic
acid.
• Detergents are effective in both hard and soft water.
Soap molecule has :
(i) Ionic (hydrophyllic) part
(ii) Long hydrocarbon chain (hydrophobic) part

Cleansing Action of Soap
• Most dirt is oily in nature and hydrophobic end attaches itself with dirt
and the ionic end is surrounded with molecule of water. This result in
formation of a radial structure called micelles.
• Soap micelles helps to dissolve dirt and grease in water and cloth gets cleaned.

• The magnesium and calcium salt present in hard water react with soap
molecule to form insoluble product called scum. This scum create
difficulty in cleansing action.
• By use of detergent, insoluble scum is not formed with hard water and
cloths get cleaned effectively.

 

ALSO SEE : 

Metals and Non-Metals

 

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