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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: autopsy on September 13, 2007, 09:53:05 AM

Title: C2H2Cl2 molecular geometry
Post by: autopsy on September 13, 2007, 09:53:05 AM
Hey all,
     I am taking chemistry in college for the first time, i feel I will do well although I am having a bit of trouble. For homework I am to come up with the 3 lewis structures for C2H2Cl2.  I have done this and have come up with 2 that are polar with chlorine pulling the electrons in whatever way the are set up, and one that is non polar because they will cancel one another out because they are on opposite corners.  I believe this is correct. He wants the bond angle and molecular geometry, this is what im unsure about.  I think it is linear because there are no lone electrons on the carbons. But at the same time the way i have it drawn makes it look bent! im really confused about that if someone would help me, i would really appreciate it so much. Thanks!
                                                                      Steph
Title: Re: C2H2Cl2 molecular geometry
Post by: Yggdrasil on September 13, 2007, 10:13:51 AM
The following wikipedia article may be helpful to read through, especially the diagram.  If you still have questions after reading the article, feel free to ask:

http://en.wikipedia.org/wiki/VSEPR
Title: Re: C2H2Cl2 molecular geometry
Post by: AWK on September 13, 2007, 10:32:47 AM
CH2Cl2 has three isomers (hint - all are flat, but not linear)
Title: Re: C2H2Cl2 molecular geometry
Post by: autopsy on September 13, 2007, 10:51:07 AM
Thank you guys for the quick responses. And thank you for the link, only i still don't understand fully. I have drawn the 3 isomers of dichloroethylene.  But in my book when we went over molecular geometry it doesn't mention anything about flat. It tells us linear, trigonal planar, tetrahedral, triagonal pyramidal, and bent.  But maybe the answer is flat, and our teacher is just throwing us a curveball.
Title: Re: C2H2Cl2 molecular geometry
Post by: AWK on September 13, 2007, 10:54:31 AM
You have two carbon trigonal planar, and both triangles are coplanar. This cause the whole molecule is flat.
Title: Re: C2H2Cl2 molecular geometry
Post by: autopsy on September 13, 2007, 10:58:57 AM
Thank you AWK :) . So because you have two tiagonal planars, it causes the whole entire molecule to be considered flat?