What are the postulates of molecular orbit theory?

Answer 1

Molecular Orbital Theory (MOT):

•

Basic idea of MOT is that atomic orbitals of individual atoms combine to

form molecular orbitals. Electrons in molecule are present in the

molecular orbitals which are associated with several nuclei.

•

The molecular orbital formed by the addition of atomic orbitals is called

the bonding molecular orbital (

s ).

•

The molecular orbital formed by the subtraction of atomic orbital is called

anti-bonding molecular orbital (

s*).

•

The sigma (s ) molecular orbitals are symmetrical around the bond-axis

while pi (p ) molecular orbitals are not symmetrical.

•

Sequence of energy levels of molecular orbitals changes for diatomic

molecules like Li

2, Be2, B2, C2, N2 is 1s < *1s < 2s< *2s < ( 2px = 2py)

<

2pz < ( *2px= *2py) < *2pz

•Sequence of energy levels of molecular orbitals changes for diatomic

molecules like O

2, F2, Ne2 is 1s < *1s < 2s < *2s <2pz<( 2px = 2py)

<

( *2px= *2py) <*2pz

Bond order (b.o.) is defined as one half the difference between the number

of electrons present in the bonding and the anti-bonding orbitals.