Polar Covalent Bonds

Covalent bonds involve the sharing of electrons between atoms.

Consider the term "sharing". Does this mean equal sharing or unequal sharing?

Think about sharing a Kit Kat chocolate bar with a friend. Does this mean that both of you get 2 fingers from this chocolate bar or could you have 3 fingers and give your friend only 1 finger? Would that be sharing? Sure! Sharing does not mean that the sharing was done equally! The sharing could be equal or it could be unequal and still be called sharing.

So too with electrons. If the electron pair that is shared between two atoms spends equal time with each atom, then the electron pair is equally shared and we have a nonpolar covalent bond with no ionic character.

If the electron pair that is shared between two atoms spends more time with one atom than the other, then we have a polar covalent bond.

In a polar covalent bond, the atom that has the electron pair more of the time will be more negative than a neutral atom. It is said to be slightly negative and is given the label of (meaning slightly negative). The atom that gets the electron pair less of the time will be lacking a negative some of the time so it is given the label (meaning slightly positive). These labels are placed above the elements symbols when you draw a structural formula for a compound.