Class 10 Chemistry



Carbon and Its Compounds

Unsaturated Hydrocarbons

Alkene: Hydrocarbons having at least one double bond between two carbon atoms are known as ALKENE. General formula of alkene is CnH2n; where n is number of carbon atoms.

If C = 1 then CnH2n = C1H2x1 = CH2

Name of this compound: Since, hydrocarbon having one carbon atom is known as Methane. Thus, Methane – ane + ene = Methene. But, alkene does not exist with one carbon atom, thus, methene does not exist.

If C = 2 then CnH2n = C2H2x2 = C2H4

Name of this compound is: ethane − ane + ene = ethene. This molecule can be shown by following structural formula.

structural formula ethene

If C = 3 then CnH2n = C3H2x3 = C3H6

Name of this compound is: butane − ane + ene = butene. This molecule can be shown by following structural formula.

structural formula butene

Other alkenes are formed in similar way.

Alkyne

Hydrocarbons having at least one triple bond between two carbon atoms are known as alkyne. (Alkane – ane + yne = Alkyne). Similarly;

Ethane – ane + yne = Ethyne
Propane – ane + yne = Propyne
Butane – ane + yne = Butyne
Pentane – ane + yne = Pentyne

General formula of alkyne is CnH2n − 2. As in case of alkene, minimum two carbon atoms are required to form alkyne.

If C = 2, then; CnH2n − 2 = C2H2x2 − 2 = C2H2

The name of this compound is ethyne. This can be shown by following structural formula.

structural formula ethyne

If C = 3, then; CnH2n − 2 = C3H2x3 − 2 = C3H4

The name of this compound is propyne. This can be shown by following structural formula.

structural formula propyne

If C = 4, then; CnH2n − 2 = C4H2x4 − 2 = C4H6

The name of this compound is butyne. This can be shown by following structural formula.

structural formula butyne

Other alkynes are formed in similar way.


Cyclic Hydrocarbon:

Carbon can form cyclic structure combining with carbon atoms. Such hydrocarbons are known as cyclic hydrocarbon. Structural formulae of some of the cyclic hydrocarbons are as follows:

structural formula cyclopentane
structural formula cyclohexane structural formula benzene
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Carbon: Intro

Alkane

Nomenclature

Nomenclature 2

Chemical Properties

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NCERT Intext Solution-2

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