topic 8 Flashcards
(11 cards)
1
Q
values of S and L define what is known as a term
A
- represented by a symbol
- 2S + 1 put to the power of L
- 2S + 1 is the spin multiplicity (number of orientation a systems total spin can take)
- L is represented by a letter
- can include J coupling value at the bottom
2
Q
total angular momentum quantum number, J
A
- resprents the combined effect of the orbital and spin angular momentum
- only unpaired electrons count
3
Q
each term as a spin degeneracy many electrons
A
- (2S+1)
- corresponding to the possible orientations of vector S
4
Q
for many electron atoms with unpaired electrons in degenerate orbitals
A
- no restriction on combination of L and S that can couple to form a valid term
5
Q
for many electron atoms with unpaired electrons in degenerate orbitals
A
- Pauli exclusion principle restricts the combination of L and S that can form a valid term
6
Q
for unpaired electrons in non denigrate orbitals the number of valid micro states is
A
= 4 (2l1 + 1)(2l2 +1)
7
Q
for unpaired electrons in degenerate orbitals (l1 = l2 = l) total number of micro states
A
- 2(2l+1) x (2(2l+1)-1) all dived by 2
- restrictions due to fewer ways of arranging second unpaired electron with respect to first due to Pauli exclusion principle
- division by a factor of 2 because 2 electrons are indistinguishable
8
Q
electron hole
A
- absence of an electron to form a filled sub shell
- positively charged and repel each other like electrons
- arrange holes in filled sub shell, same way you would arrange electrons in an empty sub shell
9
Q
predicting ground state term
A
- use hund’s rule (based on electron - electron interactions)
- ground state has maximum total spin S = max number of parallel unpaired spins
- among terms with equal max spin multiplicity, ground state = highest value of L
10
Q
selection rules for many - electron atoms
A
- total spin selection rule = change in S must be 0
11
Q
lowest term for a single electron is the same as
A
the lowest term for a single hole
