Butan                Buten(2)                Butin(2)

           H H H H               H H H H                 H     H		
           I I I I               I I I I                 I     I
         H-C-C-C-C-H           H-C-C=C-C-H             H-C-C=C-C-H 
           I I I I               I     I                 I     I
           H H H H               H     H                 H     H