1. POSTULATES Condition for bond formation Strength of the bond
Energy of orbitals
Spin of electrons
Unstability

2. Binding Force
Number of Covalent Bonds
Geometry of Molecules
Neutralisation of spins of electrons
Stability of covalent bonds

3. INTERACTING FORCES
e r e

5. OVERLAPPING OF ORBITALS
s – s overlap
Overlapping between two half filled s – orbitals of two different atoms containing unpaired electrons with opposite spins

6. s-s overlap

7. s – p overlap
Overlap of one half filled ‘ s ‘ and one half filled ‘ p ‘ orbital of two different atoms containing unpaired electrons with opposite spins

8. s-p overlap

9. p – p overlap
The overlap between half filled p orbital of one atom and half filled p orbital of another atom

10. p-p overlap

11. SIGMA BOND
Bond formed by axial overlapping of atomic orbitals

12. Pi BOND
Formed by sidewise overlapping of atomic orbitals

13. Comparison of Sigma & Pi bond
Sigma bond
Pi bond
Formed by axial overlapping of atomic orbitals
Formed by lateral
overlapping of atomic orbitals
Orbitals oriented along the internuclear axis
Orbitals oriented perpendicular to the internuclear axis
Extent of overlapping is more
Extent of overlapping is less

14. only p orbitals are involved
more energy is evolved
less energy is evolved
s and p orbitals are involved
only p orbitals are involved
Stronger than pi bond
weaker than sigma bond
Overlapping is symmetrical
Overlapping is unsymmetrical