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Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: 2810713 on March 08, 2005, 04:36:39 AM

Title: "Exchange Energy"?
Post by: 2810713 on March 08, 2005, 04:36:39 AM

 I had a question that why are half filled and completely filled orbitals are more stable , I got the answer that the electrons in an orbit change exchange their positions with other electrons of the same orbit or same energy [ more correctly as s& p have different energies] , while this exchange proceeds they release some energy called as EXCHANGE ENERGY , In the half filled or completely filled orbitals the no. of exchanges possible is more , so more energy is released to  attain more stability, but from where does this energy come from??? Why should an electron release energy due to exchange???

hrushikesh

Title: Re:"Exchange Energy"?
Post by: Demotivator on March 08, 2005, 02:50:37 PM

"Exchange energy" is probably a misnomer. It refers to a quantum mechanical principle of Pauli which states that "a wavefunction which describes the pair must be antisymmetric with respect to exchange of the electrons ."  This has consequences in terms of reduced shielding of the nucleus by the other electrons thus lowering the potential energies.

http://hyperphysics.phy-astr.gsu.edu/hbase/atomic/atstruct.html#c2

http://hyperphysics.phy-astr.gsu.edu/hbase/atomic/hund.html#c2

Title: Re:"Exchange Energy"?
Post by: 2810713 on March 09, 2005, 04:34:11 AM

 Thank you very much! The link was extremely excellent!!!

hrushikesh

Title: Re:"Exchange Energy"?
Post by: Mitch on March 11, 2005, 01:32:41 AM

Did I hear someone say stable? ;)

Title: Re:"Exchange Energy"?
Post by: 2810713 on March 12, 2005, 10:02:39 AM

 ???   ;)!!!

hrushikesh