Frequently Asked Question

To determine the term symbol for an atom, follow these steps:
1. Identify the electronic configuration: Determine the electron configuration of the atom in its ground state.
2. Find the total spin angular momentum (S): Sum the spin quantum numbers (ms) of all the electrons. For each electron, ms = +1/2 or -1/2. The total spin angular momentum (S) is the sum of these values.
3. Find the total orbital angular momentum (L): Sum the orbital quantum numbers (l) for all the electrons. The total orbital angular momentum (L) is the sum of these values.
4. Determine the multiplicity (2S+1): Calculate the multiplicity using the total spin angular momentum (S).
5. Determine the term symbol: The term symbol is represented as ^(2S+1)L_J.

L = 0, 1, 2, 3... corresponds to S, P, D, F... respectively.

J = |L - S| to |L + S| (in integer steps). J is the total angular momentum.
6. Apply Hund's rules (if necessary): If there are multiple possible term symbols, Hund's rules can be used to determine the ground state term symbol.
Example:
For a nitrogen atom (N), the electronic configuration is 1s²2s²2p³.
S = (1/2) + (1/2) + (1/2) = 3/2
L = 1 + 1 + 1 = 3 (which corresponds to F)
Multiplicity = (2
3/2 + 1) = 4
J = |3 - 3/2| to |3 + 3/2| = 3/2, 5/2, 7/2, 9/2
Therefore, the possible term symbols are ⁴F3/2, ⁴F5/2, ⁴F7/2, ⁴F9/2.
Note: Hund's rules would further indicate that the ground state term symbol for nitrogen is ⁴F3/2.