October 09, 2024, 04:15:57 PM
Forum Rules: Read This Before Posting


Topic: Molecular Symmetry  (Read 5316 times)

0 Members and 1 Guest are viewing this topic.

Offline zeshkani

  • Full Member
  • ****
  • Posts: 99
  • Mole Snacks: +2/-17
  • Chemist ?
Molecular Symmetry
« on: January 26, 2007, 08:03:55 PM »
hi there

can anybody explain Molecular symmetry, like the n folding, rotation operation, and improper rotation, inversion,  i mean the teacher did cover it, but it was so difficult to understand, and he went through it to fast.
anybody that can help or advise something, would be great thanks

Offline Bakegaku

  • Full Member
  • ****
  • Posts: 269
  • Mole Snacks: +20/-5
  • Gender: Male
  • Hydrogen peroxide is my miracle cure to everything
Re: Molecular Symmetry
« Reply #1 on: January 26, 2007, 10:31:32 PM »
We'd like to help you, but something as vague as that will be difficult to answer.  Try searching for molecular symmetry on google, then coming back with some specific questions on the matter.

7&8:
http://www.chemicalforums.com/index.php?page=forumrules
"True knowledge exists in knowing that you know nothing"
-Socrates

"I see, I forget.  I hear, I remember.  I do, I understand"
-Confucius

"Nothing will benefit human health and increase chances for survival of life on Earth as much as the evolution to a vegetarian diet."
- Albert Einstein?

"American cartoons place characters in situations; anime
places situations around characters.  Anime characters
are not like fictional characters but more like fictional
people; their actions stem directly from their personalities,
and not just as a means to move the story's plot
forward.  We are made to sympathize with them, and
not simply be entertained by them."
~John Oppliger~

Offline enahs

  • 16-92-15-68 32-7-53-92-16
  • Retired Staff
  • Sr. Member
  • *
  • Posts: 2179
  • Mole Snacks: +206/-44
  • Gender: Male
Re: Molecular Symmetry
« Reply #2 on: January 26, 2007, 10:31:46 PM »
I would start here and review with this:
http://www.ch.ic.ac.uk/local/symmetry/

Then ask again with what you need more clarification with.

Offline Goldfingers

  • New Member
  • **
  • Posts: 5
  • Mole Snacks: +0/-0
Re: Molecular Symmetry
« Reply #3 on: February 10, 2007, 08:44:05 PM »
A good way to learn to identify symmetry elements in a point group is to construct some complexes with a chemical model set, find out what point group they belong to to and look it up in a character table (can be found in any inorganic chemistry book, atkins phys. chem etc). It will give you all the members of that symmetry group, i.e. all elements of the form Cn, Sn, I, sigma h's, v's and d's.

Start with simple molecules like water, ammonium, benzene. (C2v, C3v and D6h). Build, them with a chemical model set and play around with them and try to identify the symmetry elements that are in the character table . After you have learnt to identify symmetry elements, build some inorganic octahedral and tetrahedal complexes and try to ligate them in as many ways you can. After a bit of practise, you should be fine.

The basic concepts of proper and improper rotations, mirror planes and centers of symmetry can be found in almost any inorganic or physical chemistry course book. However one book that is ofter used and provides a very simple  step by step guide to chemical group theory is (inexpensive paperback):

Molecular Symmetry and Group Theory : A Programmed Introduction to Chemical Applications, 2nd Edition  by Alan Vincent

The best advanced text book (very valuable as reference), that also provides you with the basic mathematical machinery of group theory, and is the classic in this subject is:

Chemical Applications of Group theory by Albert Cotton, (now in 3rd edition i believe). You can probably get hold of it from your university library.

Many people have a very hard time to learn molecular symmetry from a blackboard, not only you, so practise with real 3d structures help a lot. As previously said, you can probably get the answers to your questions from the above links, dont hesitate to ask if you need clarifacation on any concepts.

Sponsored Links