The ground-state term of an atom

The lowest-energy term, the ground-state term, is easily found by using Hund s first and second rules  

The term with the lowest energy has the highest multiplicity, equivalent to the highest total spin quantum number, S. 

For terms with the same value of multiplicity, the term with the highest value of L is lowest in energy. 

There is a simple method of determining the ground state of any atom or ion. The procedure is as follows. 

A number of Madelung constants for a compound appear in the literature. These usually differ from each other in the molecular unit chosen for evaluation (e.g. M X or MX / ) and whether the ionic charges are included in the constant. If 

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