Alkynes -

What are Alkynes:

These are the hydrocarbons in which carbon atoms are connected by triple bonds .

Example: Ethyne

  • Formula of Ethyne is C 2 H 2
  • There is a triple bond between 2 carbon atoms.
  • Since a carbon atom has 4 valence electrons and 3 of them are shared by another carbon atom, the remaining 1 electron is shared by a hydrogen atom each.
  • Hence there are a total of 1+1=2 Carbon Atoms and 1+1=2 hydrogen atoms .

STEPS SHOWING FORMATION OF ETHYNE - Teachoo.jpg

General formula for Alkynes

It Is C n H 2n-2

  • Where n is the number of carbon atoms.

 

Number of Carbon Atoms (n)

n=2

n=3

n=4

Name of Alkyne

Ethyne

Propyne

Butyne

Structure

   

 

 

Example : Butyne

  • In butyne, there are 4 carbon atoms.
  • So, the formula is:

C n H 2n-2

  • Putting n=4,

            C 4 H 2*4-2

            C 4 H 8-2

            C 4 H 6

BUTYNE - Teachoo.jpg

Name of Alkyne

Formula Derivation C n H 2n-2

Number of carbon atoms (n)

Ethyne

C 2 H 2

n=2

Propyne

C 3 H 4

n=3

Butyne

C 4 H 6

n=4

Pentyne

C 5 H 8

n=5

Hexyne

C 6 H 10

n=6

Heptyne

C 7 H 12

n=7

Octyne

C 8 H 14

n=8

Nonyne

C 9 H 16

n=9

Decyne

C 10 H 18

n=10

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo