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### Topic: Questions on plane of symmetry  (Read 10175 times)

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#### batmankiller

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##### Questions on plane of symmetry
« on: December 06, 2009, 12:35:16 PM »
Now I understand the concept of rotating an ethane into staggered/eclipse and i also understand some of the concepts of rotation of the methyl groups to form symmetry. But could someone provide a link or something to help me understand planes of symmetry more? For example like how does staggered have 3 planes of symmetry and how would you go about it. Is it just picking the 3 seperate hydrogens of the ethane and they would all be inversion symmetry? I'm also not very sure how to like find inversion symmetry. Because couldn't cut the ethane eclipsed confromation straight down the middle and you would have two mirror images but eclipsed has no center of symmetry.. why? Am i getting the definition wrong? and if so how would ethane have it's plane of symmetry? I understand axis of symmetry being just the number of rotations of a group to get back to the "original" form but it's just all confusing. My textbook is trash in that it's short and only 500 pages and doesn't go in-depth in anything.

I read http://www.chemicalforums.com/index.php?topic=6666.0, but still not very sure.

Thanks!

#### Markovnikov

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##### Re: Questions on plane of symmetry
« Reply #1 on: December 06, 2009, 02:13:58 PM »
http://en.wikipedia.org/wiki/Molecular_symmetry
http://symmetry.otterbein.edu/tutorial/ethane.html
is a good place to start.

A plane of symmetry is a plane through the molecule where each side of the molecule is exactly the same as the one of the other plane. For the staggered ethane molecule planes of symmetry stretches from one hydrogen of one of the carbons to the hydrogen on the carbon one the opposite side.

Inversion symmetry is available with all structures that can perform a S2. That is a C2 rotation and a reflection orthogonal of the rotational axis. The staggered structure has an point of inversion while the eclipsed structure does not. If you aren't able to see it, I would advise you to build a 3D model (or click on the second link I posted)
« Last Edit: December 06, 2009, 02:34:56 PM by Markovnikov »