100 likes | 604 Views
Calculating formal charge:. FC = Ve – (LP’s + ½ Be’s ) Formal charge is used to find the most stable structure for a molecule. The arrangement that has the lowest range of formal charges on it’s atoms is the most stable. FC = formal charge Ve = valence electrons
E N D
Calculating formal charge: FC = Ve – (LP’s + ½ Be’s) Formal charge is used to find the most stable structure for a molecule. The arrangement that has the lowest range of formal charges on it’s atoms is the most stable. FC = formal charge Ve = valence electrons LP = lone pair electrons Be = bonding pair electrons
Calculating formal charge: FC = Ve – (LP’s + ½ Be’s) Calculate each atom separately Oxygen Ve = 6 Lpe = 4 Bpe = 4 FC = 6 – (4+(1/2 x 4) = 0 Carbon Ve = 4 Lpe = 0 Bpe = 8 FC = 4 – (0+(1/2 x 8) = 0 O C O O C
Calculating formal charge: FC = Ve – (LP’s + ½ Be’s) Calculate each atom separately Oxygen 1 Ve = 6 Lpe= 4 Bpe= 4 FC = 6 – (4+(1/2 x 4) = 0 Oxygen 2 Ve = 6 Lpe = 0 Bpe = 8 FC = 6 – (0+(1/2 x 8) = 2 Carbon Ve = 4 Lpe= 4 Bpe= 4 FC = 4 – (4+(1/2 x 4) = -2 O O C O O C
Calculating formal charge: • Range of formal charge for • 0 2 -2 • Range = 2 - -2 = 4 • Range of formal charge for • 0 0 0 • Range = 0 O C O O O C
Calculating formal charge: • Step 1 Write equation • Step 2 Calculate the formal charge for each atom • Step 3 repeat until FC of every atom is found • Step 4 Find the range in formal charge for the molecule ( most positive – most negative) • Step 5 Compare FC for different configurations lowest range is most stable