What is electronegativity?

Explanation

The relative tendency of an atom in a covalent molecule to attract the shared pair of electrons towards itself is called its 'electronegativity'.
Pauling's scale : In this method, E.N. is calculated from the bond energies. The following expression is used
`X_(A) - X_(B) = 0.208sqrt(Delta)`
Where `X_(A)` = E.N. of atom `A, X_(B)` = E.N. of atom `B, Delta` = Bond polarity, where `Delta` is in `"kcal"//"mole"`.
Bond polarity = Experimental bond energy - Theoretical bond energy.
`Delta = E_(A-B) - 1/2 (E_(A-A) + E_(B-B)` where
`E_(A_B)` = Bond energy of A-B moleules (experimental)
`E_(A-A)` = Bond energy of A-A molecule
`E_(B-B)` = Bond energy of B-B molecule
Metals are electropositive. So they possess low E.N. values. Non-metals are eletronegative. So they possess high E.N. values.