The document discusses spectroscopic term symbols, which represent the energy, angular momentum, and spin multiplicity of atoms, particularly in relation to hydrogen. It details how these symbols are defined for different atomic orbitals (s, p, d, f) and explains the splitting of d and f terms in an octahedral field. Additionally, it includes information on determining term symbols and presents Orgels diagrams for illustrating these concepts.

1. Spectroscopic
Term symbols
Mr. Mithil Fal Desai, Ph. D.
Assistant Professor in Chemistry
Shree Mallikarjun and Shri Chetan Manju
Desai College
Canacona, Goa

2. 2
The term symbols are a symbolic representation of energy,
angular momentum and spin multiplicity of an atom.
For a Hydrogen atom it is defined as S, P, D, F states,
depending upon the electron occupancy in s, p, d and f
orbitals.
Term Symbol

3. L 0 1 2 3
Ground term S P D F
Components in
octahedral field
A1g T1g T2g, Eg A2g, T1g, T2g
Splitting of dn terms in an octahedral field
3

4. No. of d
electrons
l
Orbital
momentu
m
Term Total spin (S)
Free
ion
ground
state
Ground
term in
octahedral
field
Excited state
term with
same spin
multiplicity
2 1 0 -1 -2 Σl=L Σs=S 2S+1 2S+1L
1 ↑ - - - - 2 D 1/2*1 2 2D 2T2g
2Eg
2 ↑ ↑ - - - 3 F 1/2*2 3 3F 3T1g
3T2g,3A2g, 3T1g(P)
3 ↑ ↑ ↑ - - 3 F 1/2*3 4 4F 4A2g
4T2g,4T1g, 4T1g(P)
4 ↑ ↑ ↑ ↑ - 2 D 1/2*4 5 5D 5Eg
5T2g
5 ↑ ↑ ↑ ↑ ↑ 0 S 1/2*5 6 6S 6A1g None
6 ↑↓ ↑ ↑ ↑ ↑ 2 D 1/2*4 5 5D 5T2g
5Eg
7 ↑↓ ↑↓ ↑ ↑ ↑ 3 F 1/2*3 4 4F 4T1g
4T2g,4A2g, 4T1g(P)
8 ↑↓ ↑↓ ↑↓ ↑ ↑ 3 F 1/2*2 3 3F 3A2g
3T2g,3T1g, 3T1g(P)
9 ↑↓ ↑↓ ↑↓ ↑↓ ↑ 2 D 1/2*1 2 2D 2Eg
2T2g
Determination of term symbols
4

5. D
T2g
Eg
F
T1g
A2g
T2g
Splitting of ground terms by an octahedral field
d1
d2
5

6. Eg
Splitting of D term by an octahedral field
T2g
T2g
Eg
d1 and d6
d4 and d9
2D
Dq
Orgel diagram
6

7. A2g
T2g
Splitting of F term by an octahedral field
T1g
T1g
d2 and d7
d3 and d8
Dq
T2g
A2g
T1g (P)
(P)
(F)
T1g (P)
Orgel diagram
7