Molecular orbital theory explanation

Molecular Orbital Theory (MOT):

 

  1) Electrons in a molecule are present in various molecular orbitals as the electrons of atoms are present in various atomic orbitals.

 
  2)  Atomic orbitals of comparable energies and proper symmetry combine to form molecular orbitals.

 
  3)  While an electron in an atomic orbital is influenced by one nucleus, in a molecular orbital it is influenced by two or more nuclei depending on the number of atoms in the molecule. 
        Thus, an atomic orbital is monocentric, while a molecular orbital is polycentric.

 
  4) The number of molecular orbitals formed is equal to the number of combining atomic orbitals. 

   5)  When two atomic orbitals combine, two molecular orbitals are formed. One is known as bonding molecular orbital, while the other is called antibonding molecular orbital.
        The bonding molecular orbital has lower energy and hence greater stability than the corresponding antibonding molecular orbital.

   6) Just as the electron probability distribution around a nucleus in an atom is given by an atomic orbital, the electron probability distribution around a group of nuclei in a molecule is given by a molecular orbital.
         

    7)The molecular orbitals such as atomic orbitals are filled in accordance with the aufbau principle obeying the Pauli’s exclusion principle and the Hund’s rule.