1. BOND CHARACTERSTICS
LESSON 3
PART-1

2. TOPICS WE HAVE TO COVER IN BOND CHARACTERSTICS
PART -1:
1) BOND LENGTH
2)BOND ANGLE
3)BOND ENTHAPLY

3. 1)BOND LENTH
1) It is the equilibrium distance between two bonded atoms in a
molecule.
2) Each atom of the bonded pair contributes equal to the bond length.
3) It is expressed in terms of angstrom(A*) or picometer (pm).
Similarly , in a covalent compound , bond length is obtained by adding
up the covalent radii of two bonded atoms.
The covalent radius is half of the distance between two similar atoms
joined by a covalent bond in the same molecule.

6. VANDEWAAL RADII
The half of the bond length between two non- bonded atoms
hold together by vander waal force of attraction.

7. SOME POINTS REGARDING BOND PARAMETERS:
(1)Triple bonds are considered to be the strongest
bonds followed by double and single bonds and
as we know, bond length decreases as the bond
strength increases (due to increased attractions
or due to formation of more bonds)
(2)The bond length of the homonuclear diatomic
molecules are twice the covalent radii.

8. (3) BOND ENTHAPLY
It is defined as amount of energy required to break one mole of
bonds of a particular type between two atoms in gaseous state.
The unit of bond of enthalpy is in KJ/mol.
Stronger the bond larger bond enthalpy we
required.

9. SOME POINTS REGARDING BOND strength:
(1) Strength of sigma bond is more than pi bond.
(2)Resonance in the molecule affect the bond
energy.
(3)Bond energy decreases down the group in case of
similar molecules
(4)Bond energy increase in the following order:
s < p < sp < sp2 < sp3
(5)Bond energy decresae with the increase in the
number of lone pair.
C – C > N – N > O – O
(No lone pair) (One lone pair) (Two
lone pair)

10. (2) BOND ANGLE
(1) It is defined as the angle between the orbitals containing bonding electron pairs
around the central molecule.
(2) It help us in determining it’s shape.
For example H-O-H bond angle in water can be represented as

11. (1) Lone pair repulsion: Bond angle is affected by the
presence of lone pair of electrons at the central atom. A
lone pair of electrons at the central atom always tries to
repel the shared pair (bonded pair) of electrons. Due to
this, the bonds are displaced slightly inside resulting in a
decrease of bond angle.
(2) If the electronegativity of the central
atom decreases, bond angle decreases.
(3) Hybridization: Bond angle depends on the state of hybridization of the central atom
Hybridization: sp3, Bond angle: 109∘29Example: CH4
Hybridization: sp2, Bond angle: 120∘, Example: BCl3
Hybridization: sp,Bond angle: 180∘, Example: BeCl2
Generally s- character increase in the hybrid bond, the bond angle increases

12. Relation between bond order, bond
length, bond enthalpy