ELECTRONEGATIVITY

Electronegativity

It is a withdrawing capacity of bonded atom within a molecule.

For example in AB molecule if electronegativity of A is more than B, then A-B  is polar molecule and A atom gets partially negative charge and B atom gets partially positive charge.

In periodic table Fluorine (F)is highest electronegative element its electronegativity is4.0 according to pauling scale.

Some important electronegativity value of some nonmetal according to pauling scale

H-2.1

C-2.5

N-3.0

O-3.5

F-4.0

Cl-3.0

Etc.

Due to electronegativity difference a molecule become polar .Some polar polar attractive forces are H-bonding (one of the bonded atom is hydrogen),dipole dipole attraction etc.This attractive force again responsible for exist in differnt state(i.e,
Solid,liquidor gasious).

Acidity of a molecule depend on the electronegativity of the atom which is bond with hydrogen atom.If the electronegativity of this atom is high then this bond is highly polar so hydrogen easily liberated i.e acidity is high.