In: Chemistry
What spin functions are allowed for the inner pair of electrons (1s2) in the 1s22s configuration of Li? What spin functions are allowed for the outer electron (2s) in the same configuration?
Lithium has atomic number, Z = 3
Electronic arrangement is 2,1 and configuration 1s2 2s2 in the ground state
According to Pauli’s exclusion principle, ‘no two electrons in atom can have identical set of quantum numbers ‘ ; this emphasizes the fact that an orbital can accommodate maximum two electrons.
On the basis of quantum mechanical model, Linear Combination of Atomic Orbitals is used to arrive the symmetric and antisymmetric functions ( both spatial and spin)
1
Ψ (r1,r2) = --- [ ψ1s ά ( r1) ψ1s β (r2)] - [ ψ1s ά ( r2) ψ1s β (r1)] for 1s2
√2
For the 2s1 electron, ψ2s function is to be used
The quantum numbers are : n ln ml s
1s2 1 0 0 + ½
1 0 0 - ½
2s1 2 0 0 + ½ or – ½