Unshared, or lone, electron pairs play an important role in determining the chemical and physical properties of organic compounds. Thus, it is important to know which atoms carry unshared pairs. Use the structural formulas below to determine the number of unshared pairs at each designated atom. Be sure your answers are consistent with the formal charges on the formulas. The number of unshared pairs at atom a is .

The number of unshared pairs at atom b is .

The number of unshared pairs at atom c is .