how to find Na and Nb in any molecule like Li2,C2,He2 like that?????????? ans me quick
Na is the number of electrons present in antibonding orbital while Nb is the number of electrons present in the bonding orbital.
Antibonding orbital is represented by the star mark.
Lets take an example of lithium.
Lithium Molecule (Li2)
Li-atom : 1s2 2s1
Li2 : (σ1s)2 (σ*1s)2 (σ2s)2
There are two electrons which are present in antibonding orbital (represented by the star) and 4 electrons which are present in the bonding orbital.
or, KK(σ2s)2, where KK = closed K shell structure (σ1s)2 (σ*1s)2
Bond order =
Similarly, you can try for the other molecules.