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CHAPTER – 4

CARBON AND ITS COMPOUNDS
q

Carbon is a versatile element
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02% and found in form of minerals
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03% of Carbon dioxide
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Covalent Bond in Carbon
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The atomic number of carbon is 6 and its electronic configuration is 2, 4
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Gain 4 electrons
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2
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But it would require a large amount of energy to remove
4 electrons
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Carbon attains the noble gas configuration by sharing its valence electrons
with other atoms
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Formation of H2, O2 and N2 is shown as below :

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It is evident that the number of shared pair of electrons can be one, two or
three
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Bond formed by the sharing of an electron pair between two atoms is called
covalent bond
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These molecules are generally poor conductor of electricity since no charged
particles are formed
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CATENATION : property of carbon atom to form bond with other atoms of
carbon is called catenation
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TETRAVALENCY : Having a valency of 4, carbon atom is capable of bonding
with atoms of oxygen, hydrogen, nitrogen, sulphur, chlorine and other elements
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Saturated and Unsaturated Carbon Compounds

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ALKANE : CnH2n+2

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ALKENE : CnH2n

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ALKYNE : CnH2n–2

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Electron dot structure of a saturated carbon compound, ethane is as follows:

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Electron dot structure of an unsaturated cabon compound, ethene is as follows:

TRY DRAWING THE ELECTRON DOT STRUCTURE OF ETHYNE
Formulae and Structures of Saturated Compounds of Carbon and Hydrogen

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On the basis of structures the hydrocarbons can be:

Structural isomers : these are the compounds having identical molecular formula
but different structures
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Heteroatom and Functional Group :
*In hydrocarbon chain, one or more hydrogen atoms can be replaced by other
atoms in accordance with their valencies
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*These heteroatoms and the group containing them impart chemical properties to
the compound and hence are called functional groups
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For instance, the ALCOHOLSs: CH3 OH, C2H5 OH, C3H7 OH, C4H9 OH
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The chemical properties are imparted by the functional group thus all members
have similar chemical properties
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The physical properties vary among the members of homologous series due
to difference in their molecular mass
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Nomenclature of Carbon Compounds:
1
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2
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Functional Group
Suffix
Prefix
Alkene
ene
Alkyne
yne
Alcohol
ol
Aldehyde
al
Ketone
one
Carboxylic acid
oic acid
chlorine
chloro
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3
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methanol
(methane-e = methan + ol)
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COMBUSTION :

*Carbon compounds generally burn (oxidize) in air to produce carbon dioxide and
water, and release heat and light energy
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*Sooty flame is seen when unsaturated hydrocarbons are burnt
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2
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CH 3 - CH 2 OH

3
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Vegetable oils are converted into vegetable ghee using this process
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4
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→
CH4 + Cl2  CH3Cl + HCl (sunlight required)

IMPORTANT CARBON COMPOUNDS : Ethanol and Ethanoic Acid
Ethanol :

*Consumption of dilute ethanol causes serious health issues and intake of pure
alcohol is lethal
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*Pure acetic acid is called glacial acetic acid
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Hydrolysis :
On heating with an acid or a base the ester forms back the original alcohol and
carboxylic acid
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H 2 SO 4

→
HEAT

CH3COOH + CH3-CH2OH

*Alkaline hydrolysis of ester is also called saponification
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Soaps are effective with soft water only and ineffective with hard water
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They are effective with both soft as well as hard water
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Structure of a Soap Molecule
Cleansing Action of Soaps :
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Most dirt is oily in nature and the hydrophobic end attaches itself with dirt,
while the ionic end is surrounded with molecules of water
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An emulsion is thus formed by soap molecule
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Scum : The magnesium and calcium salts present in hard water reacts with
soap molecule to form insoluble products called scum, thus obstructing the
cleansing action
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EXERCISE
(Question Bank)
1MARK
1
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Draw the electron dot structure of a molecule of water
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Define catenation
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The kerosene/gas stove used at home has inlets for air
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5
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Sulphuric acid
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Write the number of covalent bonds present in propane
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Define the term: oxidising agent
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Write the formula for first member of ketone
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Would you be able to check if water is soft by using a soap?

10
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2 MARKS
1
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Write a chemical equation for it
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Covalent compounds generally don't conduct electricity
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Specify the condition in which ethanol undergo oxidation to form ethanoic
acid
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4
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Draw the structures of the two isomers of butane
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Identify the functional group present in the following compounds: HCOOH,
HCHO, CH3Br and C10H21OH

3 MARKS
1
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2
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5 MARKS
1
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2
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This compound reacts with ethanol to form a sweet smelling
compound 'B'
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ii)

Write the chemical equation for its reaction with ethanol to form
compound 'B'
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iv)

Which gas is produced when compound 'A' reacts with washing soda?
Write the chemical equation

v)

How can vinegar be obtained from compound 'A'?

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CARBON AND ITS COMPOUNDS IN BRIEF
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Carbon is a versatile non-metal
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Carbon forms large number of compounds due to catenation and tetravalency
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The compounds of hydrogen and carbon are called hydrocarbons, which can
be saturated or unsaturated
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Difference in Structural arrangement of same molecule gives rise to isomerism
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Homologous series is a series of compounds with same general formula and
same chemical properties but different physical properties
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Ethanol is an important industrial compound
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Ethanoic acid is another important compound
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Soaps and detergents are used as cleansing agents
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