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 .
General formula for Alkynes
It Is C _{ n } H _{ 2n2 }
 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 _{ 2n2 }
 Putting n=4,
C _{ 4 } H _{ 2*42 }
C _{ 4 } H _{ 82 }
C _{ 4 } H _{ 6 }
_{ }
Name of Alkyne 
Formula Derivation C n H 2n2 
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 