Organic Chemistry Practice Problems and Problem Sets
formal charge
For each molecule, determine the formal charge of the indicated atom.
Remember that when calculating formal charge, you count both electrons in a lone pair but only half of the electrons in a bonding pair. This is why a helpful formula is:
For example, in the first compound (the protonated oxygen), the oxygen has one lone pair ("2 dots") and three bonding pairs ("3 sticks"). Oxygen has a valence of 6, so its formal charge in this species is 6 - 5 = 1 or +1.
MendelSet practice problem # 310 submitted by Matt on June 7, 2011.