CHEM2210 Chapter Notes - Chapter 2: Total Angular Momentum Quantum Number, Ground Expression, Term Symbol
Spin-Orbit Coupling
Coupling occurs between the resultant spin and orbital momenta of an
electron, which gives rise to J the total angular momentum quantum number.
Multiplicity occurs when several levels are close together and is given by the
formula (2S+1). The Russell Saunders term symbol that results from these
considerations is given by:
The Russell Saunders term symbols for the other free ion configurations:
Hund's Rules
The Ground Terms are deduced by using Hund's Rules. The two rules are:
1. The Ground Term will have the maximum multiplicity
2. If there is more than 1 Term with maximum multiplicity, then the
Ground Term will have the largest value of L.
To calculate S, simply sum the unpaired electrons using a value of ½ for
each. To calculate L, use the labels for each column to determine the value
of L for that box, then add all the individual box values together.
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Document Summary
Coupling occurs between the resultant spin and orbital momenta of an electron, which gives rise to j the total angular momentum quantum number. Multiplicity occurs when several levels are close together and is given by the formula (2s+1). The russell saunders term symbol that results from these considerations is given by: The russell saunders term symbols for the other free ion configurations: The ground terms are deduced by using hund"s rules. The two rules are: the ground term will have the maximum multiplicity, if there is more than 1 term with maximum multiplicity, then the. Ground term will have the largest value of l. To calculate s, simply sum the unpaired electrons using a value of for each. To calculate l, use the labels for each column to determine the value of l for that box, then add all the individual box values together. The other thing to note is the idea of the hole approach.
