What is Multiplicity?
Spin multiplicity is a quantum mechanical concept that describes the number of possible orientations of the total electron spin in an atom or molecule. It is given by the formula 2S + 1, where S is the total spin angular momentum.
Common Terms
Important multiplicity terms:
- Singlet: All electrons paired (M = 1)
- Doublet: One unpaired electron (M = 2)
- Triplet: Two unpaired electrons (M = 3)
- Quartet: Three unpaired electrons (M = 4)
- Quintet: Four unpaired electrons (M = 5)
Applications
Multiplicity is important in:
- Spectroscopy
- Magnetic properties
- Chemical reactivity
- Photochemistry
- Molecular orbital theory
Term Symbols
Components of term symbols:
- Spin (S): Total spin angular momentum
- Orbital (L): Total orbital angular momentum
- Total (J): Total angular momentum
- Notation: ²ˢ⁺¹L_J