Formal Charges and Resonance Structure Flashcards
1
Q
What is formal charge?
A
a figure that reflects the charge that would reside on the atom if all of the bonding electrons were shared equally.
Formal Charge = (# of valence electron) - (Non-Bonding Electrons) - (Bonds)
2
Q
What does it mean for an element to have a formal charge of zero?
A
An atom is following its normal valency (typical # of bonds and lone pair)
3
Q
Normal Valency for Boron
A
3 covalent bonds
0 lone pair
4
Q
Normal Valency for Carbon
A
4 covalent bonds
0 lone pairs
5
Q
Normal Valency for Nitrogen
A
3 covalent bonds
1 lone pair
6
Q
Normal Valency for Oxygen
A
2 Covalent Bonds
2 Lone Pairs
7
Q
Normal Valency for Fluorine
A
1 Covalent Bond
3 Lone Pairs
8
Q
Rules for Resonance
A
The tail of the arrow always begin at
- lone pair
-pi bond
BUT NEVER sigma bond
note: must obey octet rule
