How is the sequence of energy levels of molecular orbitals written in case of heavier diatomic molecules?

How is the sequence of energy levels of molecular orbitals written in

1.	How is the sequence of energy levels of molecular orbitals written in case of heavier diatomic molecules?
Answer» Solution :For heavier DIATOMIC molecules , the ORDER of energy levels of `sigma_(2)p_(z) , pi_(2)p_(X), pi_(2)p_(y)` is reversed , (i.e.) `sigma_(2)p_(z)` has lesser energy than `pi_(2)p_(x)` and `pi_(2)p_(y)`. HENCE , the order of increasing energies of Mos is , `sigma_(1S) lt sigma_(as)^() lt sigma_(2s) lt sigma_(2s)^() lt sigma_(2)p_(z) lt pi_(2)p_(x) = pi_(2)p_(y) lt pi_(2)^() p_(x) = pi_(2)^()p_(y) lt sigma_(2)p_(z)`.