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Hund's rules (Read 2684 times)
Gerrit-Jan Linker
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Hund's rules
02.04.09 at 08:43:30
 
Hund's rules
 
Quote:
A rule for building up the electronic configuration of atoms and molecules. Where a species possesses degenerate orbitals one electron is placed into each of these before two electrons are placed in any one of the degenerate set, and the electrons in the singly occupied orbitals have parallel spins.  Thus, the ground state electron configuration of the nitrogen atom is represented by N(1S22S22px12py12pz1).

 
Quote:
Hund's rules. The three rules are:

1. For a given electron configuration, the term with maximum multiplicity has the lowest energy. Since multiplicity is equal to 2S+1, this is also the term with maximum S.
2. For a given multiplicity, the term with the largest value of L has the lowest energy.
3. For a given term, in an atom with outermost subshell half-filled or less, the level with the lowest value of  J lies lowest in energy. If the outermost shell is more than half-filled, the level with highest value of J is lowest in energy.

 
Sources:
IUPAC: GLOSSARY OF TERMS USED IN THEORETICAL ORGANIC CHEMISTRY
http://old.iupac.org/publications/pac/1999/71_10_pdf/7110mirkin_1919.pdf
List of Hund's rules
http://en.wikipedia.org/wiki/List_of_Hund's_rules
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« Last Edit: 02.04.09 at 09:16:23 by Gerrit-Jan Linker »  

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