Depending on the relative electronegativities of the two atoms sharing electrons, there may be partial transfer of electron density from one atom to the other. When the electronegativities are not equal, electrons are not shared equally and partial ionic charges develop.
The greater the electronegativity difference, the more ionic the bond is. Bonds that are partly ionic are called polar covalent bonds.
Nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.
Nonpolar Covalent Bond
-A bond between 2 nonmetal atoms that have the same electronegativity and therefore have equal sharing of the bonding electron pair
Polar Covalent Bond
-A bond between 2 nonmetal atoms that have different electronegativities and therefore have unequal sharing of the bonding electron pair
-The result is a bond where the electron pair is displaced toward the more electronegative atom. This atom then obtains a partial-negative charge while the less electronegative atom has a partial-positive charge.This separation of charge or bond dipole can be illustrated using an arrow with the arrowhead directed toward the more electronegative atom.
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