4.1 LEWIS STRUCTURE

TYPES OF BONDING

DOUBLE BOND

Two bonding pairs of electrons
2 atoms share 4 electrons

●● ●● or ●●O●●●●●● ●●

OO O

●● ●● ●●

TRIPLE BOND

Three bonding pairs of electrons
2 atoms share 6 electrons

●● N N●● or ● N●●●●●● N ●
● ●

BOND LENGTH

Distance between nuclei of two covalently bonded
atoms in a molecule  For a given pair of atoms,

C—C > C═C > C≡C
(154 pm) (134 pm) (121 pm)

RELATION OF BOND ORDER, BOND LENGTH,
AND BOND ENERGY

bond order increase
shorter bond
stronger bond

A higher bond order results in
a shorter bond length and a higher bond energy.

EXAMPLE – 01

Rank the bonds in each set in order of
decreasing bond length:
a) C ═ O, C – O, C ≡ O

Rank the bonds in each set in order of
increasing bond strength:
b) N ═ N, N – N, N ≡ N

Ans; EXAMPLE – 01

a) C=O, C–O, C≡O
Decrease Bond length: C-C > C=C > C≡C

b) N=N, N–N, N≡N
Increase Bond strength: N-N < N=N < N≡N