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D Atomic and Molecular Term Symbols
for naming terms. We can also see that all electrons are paired in this configuration,
so that the total electronic spin S will be zero, and hence the term is a singlet term.
This gives us the term symbol 1 A 1 for the H 2 O molecule. For the NH 2 radical
(molecule), everything is the same except that the highest energy MO has only one
electron in it: hence, the electron configuration up to the half-occupied 1b 1 MO
gives a 1 symmetry, so that the outer product of this a 1 symmetry with the singly
occupied 1b 1 MO gives b 1 symmetry, which we assign as the term B 1 . There is a
single unpaired valence electron for NH 2 , so that the total electronic spin is
1
2 and
we have a doublet molecule, with term symbol 2 B 1 .
D Atomic and Molecular Term Symbols
for naming terms. We can also see that all electrons are paired in this configuration,
so that the total electronic spin S will be zero, and hence the term is a singlet term.
This gives us the term symbol 1 A 1 for the H 2 O molecule. For the NH 2 radical
(molecule), everything is the same except that the highest energy MO has only one
electron in it: hence, the electron configuration up to the half-occupied 1b 1 MO
gives a 1 symmetry, so that the outer product of this a 1 symmetry with the singly
occupied 1b 1 MO gives b 1 symmetry, which we assign as the term B 1 . There is a
single unpaired valence electron for NH 2 , so that the total electronic spin is
1
2 and
we have a doublet molecule, with term symbol 2 B 1 .