Why is chloroethene said to be a conjugated system?

Why is chloroethene said to be a conjugated system?Is it because of p orbitals present in chlorine or something?




Conjugation can be between pi-bond and another pi-bond, lone pair of electrons and a pi-bond(as in your case) and pi-bond and a vacant orbital(p or d).


 4

Chloroethene is said to be a conjugated system because the lone pair on the chlorine atom in in conjugation with the double bond between the 2 carbon atoms.


See [this](http://www.expertsmind.com/CMSImages/2061_properties%20of%20vinyl%20chloride1.png) image for the resonating structures.


 -2

Chloro ethane is a conjugated system because of the +M effect of chlorine with the double bond of ethene. Chlorine has a tendency to resonate with a double bond by donating its lone pair. What this means is that the lone pair of chlorine is in an unhybridised atomic p orbital in the same plane as the p orbital of the adjacent double bonded carbon atom, due to which, the lone pair "jumps" from the p orbital of chlorine to the adjacent carbon (forming a double bond) and displaces the original double bond to the next carbon.


[![](https://i.stack.imgur.com/nRApv.png)](https://i.stack.imgur.com/nRApv.png)


resonates to


[![](https://i.stack.imgur.com/LMVvu.png)](https://i.stack.imgur.com/LMVvu.png)


 -2