Chemistry Class 11 Chapter 4 Chemical Bonding and Molecular Structure | Page 4

Dipole moment : The product of the magnitude of the charge and the distance between the centres of positive and negative charge . It is a vector quantity and is represented by an arrow with its tail at the positive centre and head pointing towards a negative centre . Dipole moment ( μ ) = charge ( Q ) × distance of separation ( r )

SIGMA BOND : A covalent bond formed due to the overlapping of orbitals of the two atoms along the line joining the two nuclei ( orbital axis ) is called sigma ( σ ) bond . For example , the bond formed due to s-s and s-p , p-p overlapping along the orbital axis are sigma bonds .

Pi- BOND : A covalent bond formed by the side wise overlapping of p- or d- orbitals of two atoms is called as pi ( π ) bond . For example , the bond formed due to the sideways overlapping of the two p- orbitals is a pi- bond .

HYDROGEN BOND : The bond between the hydrogen atom of one molecule and a more electro- negative element of same or another molecule is called as hydrogen bond .

HYBRIDIZATION : The process of mixing of the atomic orbitals to form new hybrid orbitals is called hybridization . All hybrid orbitals of a particular kind have equal energy , identical shapes and are symmetrically oriented in shape .

The hybrid orbitals are designed according to the type and the atomic orbitals merging together , e . g .,

Molecule Type Example

AX 2 E 1

AX 2 E 2

NO 2 − , SO 2 , O 3 , CCl 2

H 2 O , OF 2

2− , NO3

− , SO3

AX3E1

NH 3 , PCl 3