IMPORTANT POINTS FOR MCQS

VALENCE BOND THEORY (VBT)

(ORBITAL CONCEPT ABOUT COVALENT BOND)

This theory explains the concept of covalent bond.

1;According to this theory covalent bond is formed by the overlapping of atomic orbitals.

In overlapping orbitals, electrons become paired with opposite spin and become more stable.

2; Only half filled orbitals can overlap to form covalent bond.

☻The strength of covalent bond depends on the existing of overlapping.  Greater overlapping mean stronger the bond.

☻;Two types of bonds are formed by the overlapping of atomic orbitals i.e. sigma and Pi bonds.

☻.S – S, S – P and P – P head to head overlapping form sigma bond while P – P sidewise or  parallel overlapping form Pi – bond.

(1)        S – S Overlapping. (Formation of H₂ – molecules) E.C of H₁ = 1S

            It always form sigma bonds

(2)        S – P overlapping formation of HCl molecule.          Sigma bond is formed

(3)        P–P head to head overlapping (Formation of F₂ – molecules. Sigma bonds are formed

P – P Sidewise (Parallel overlapping) formation of O₂ and N₂ Pi bond is formed