Write the important conditions required for the linear combination of atomic orbitals to form molecular orbitals.
The given conditions should be satisfied by atomic orbitals to form molecular orbitals:
(a) The atomic orbital with one electron (completely half filled) can take part in combination or overlapping.
(b) During the time of overlap, the combining orbitals must have opposite spins of electrons.
(c) The combining atomic orbitals must have the same or nearly the same energy. This means that in a homonuclear molecule, the 1s-atomic orbital of an atom can combine with the 1s-atomic orbital of another atom, and not with the 2s-orbital.
(d) The combining atomic orbitals must have proper orientations to ensure that the overlap is maximum.
(e) The extent of overlapping should be large.