Electronegativity is a measure of the attraction of a bonded atom for the pair of electrons in a covalent bond.
A permanent dipole is a small charge difference across a bond that results a difference in the electronegativities of the bonded atoms.
A polar molecule has an overall dipole, when you take into account any dipoles across the bonds.
Polar and non-polar bonds
In a molecule of hydrogen, H2, the two bonding atoms are identical. Each hydrogen atom has an equal share of the pair of electrons in the bond, resulting in a perfect 100% covalent bond.
The nucleus of each bonded atom is attracted to the bonding electron pair.
We say that a H-H bond is non-polar - the electrons in the bond are evenly distributed between the atoms that make up the bond.
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