Why are sigma bond more stronger than pi bond ?

 Why are sigma bond more stronger than pi bond?

 A sigma bond is formed by the face to face overlapping of two 's' orbitals,one 's' and one 'p' orbitals or between two 'p' orbitals. 

On the other hand a pi bond is formed by the side wise or parallel  overlapping of two pure 'p' orbitals . 

Now, the strength of covalent bond depends on the extent of overlapping area of two orbitals. 

Since the  extent of overlapping area due to formation of sigma ❲𝞂❳ bond is greater than pi❲ π ❳ bond , so 𝞂 bond is more stronger than π bond.            

What is a sigma bond ?

The bond which formed by the face to face  overlapping  between two atomic orbital’s ( between s – s orbital’s , p – p orbital’s or s – p orbital’s ) , is called  sigma bond. 

What is a pi bond ?

The bond which formed by side wise or parallel overlapping  between two pure atomic p_y-p_y orbital’s  or p_z-p_z orbital’s , is called  sigma bond. 

What is difference between sigma and pi bond ?

Sigma bond 

(I) Sigma bond is formed  by the  face to face  overlapping  between two atomic orbital’s.

(II)  Sigma bond is formed  by the  face to face  overlapping  between two ‘s’ orbital , two ‘p’ orbital or one ‘s’ and one ‘p’ orbital’s .

( III) Sigma bond is more stable with lower energy .

(IV) It shows no bond resonance or hyper-conjugation but don't show resonance.

(V) In sigma bond electron pairs are confined between two atoms which makes it localized bonding.

(VI) Sigma bond is more stronger than other bonds. 

(VII) Compounds having localized sigma bonding are fully described by a single Lewis structure and their properties such as bond lengths, bond energies and dipole moment can be predicted easily.

(VIII) Sigma bond don't form conjugated systems because all conjugated systems have alternate single and double or triple bonds.

Pi bond

(I) Pi bond is formed due to parallel overlapping of two atomic orbital’s .

(II) Pi bond is formed due to parallel overlapping of two pure ‘p’-orbital’s ( P_Y-P_Y , P_Z-P_Z ).

(III) Pi bond is less stable with higher energy .

(IV)  Pi bond participate in resonance , but does not show hyper-conjugation .

(V) In pi bond one or more electron pairs can move from one atom to another atom which makes it delocalized chemical bonding.

(VI) Electron pair in pi bond is loosely bounded . So it is a weak bond .

(VII) Due to resonance it's stability increases and makes compounds stable.

(VIII) Pi bond show the feature of conjugated systems as all conjugated systems have alternate single and double or triple bonds.

Practice problem

• What is a sigma bond ?
• What is a bond ? 
• What is difference between sigma and pi bond ? 
• Which bond is more active between sigma and pi ? 
• Why pi bond is more active than sigma bond ?

What is pseudo tropism ?