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Name:  Monica
Status: other
Grade: other
Location:CT
Country: N/A
Date: 1/3/2006


Question:
Why is molecular geometry so important?


Replies:
Good Day,

Molecular Geometry of a compound can be predicted based on the elements present, the coordination number and the orbital hybridization. The Molecular Geometry of the compound can be used to help make predictions about crystal structures, dipole moment, reactivity, bond lengths and angles. The Molecular Geometry can be used to determine specific symmetry elements present, which in turn can predict IR and Raman bending or stretching modes which can help verify, spectroscopically, the structure of the compound of interest. Molecular geometry can also help the scientist visualize reactions of interest, reaction pathways, products or means of improving on the reaction of interest. The Molecular Geometry of well characterized compounds can be utilized in the efforts to explore new analytical spectroscopic techniques.

A strong understanding of Molecular Geometry can significantly help the Chemist.

Fred Boeheim


Monica,

At a molecular level, there are three things that control chemical reactions: (1) rate of collisions - how often the molecules come into contact, (2) the orientation of those collisions - whether the molecules come into contact in the right locations on the molecule, and (3) energy of those collisions - whether when the molecules come into contact that the energy is appropriate for a reaction to take place. #2 should indicate to you that the shape of a molecule is -in a very general way- a factor in the rate of chemical reactions.

We can go into more specifics such as: (a) if a molecule's reactive site is blocked by other parts of the molecule, then the molecule is not very reactive, (b) if a molecule is of a particular shape and will react only with other molecules of a specific shape - the way a left hand will only fit well into a left-handed glove, (c) if the target product will only come out from a specific starting shape -sort of like, you can only expect to get a left handed glove off of a left hand, etc. ---but all of these go back to #2 above.

Greg (Roberto Gregorius)



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