Page 1 of 1

### Resonance in SO4

Posted: Fri Oct 27, 2017 2:26 pm
Hi, Today in class we learnt that the resonant structure of SO4 (2-) is when S has 2 double bonds and 2 single bonds, calculated using the formal charge. Why isnt having 4 double bonds more stable since the FC will be 0 for all of the O atoms?

### Re: Resonance in SO4

Posted: Fri Oct 27, 2017 7:05 pm
Sulfur is not able to hold 16 valence electrons in its valence shell.

### Re: Resonance in SO4

Posted: Fri Oct 27, 2017 8:47 pm
Also I think we want the central atom to have a formal charge be zero, or at least as close to 0 as it can get. If we made all the oxygen atoms have a formal charge of 0, we would have the total formal charge of -2, but the structure would be less stable since the formal charge of sulfur would become -2.

### Re: Resonance in SO4

Posted: Fri Oct 27, 2017 9:42 pm
So the most important thing is to make sure the FC of the central atom is as close to 0 as possible?

### Re: Resonance in SO4

Posted: Fri Oct 27, 2017 10:24 pm
I think the goal is the have the formal charge of all atoms to be as low as possible but having 4 double bonds for S is not possible.

### Re: Resonance in SO4

Posted: Fri Oct 27, 2017 10:33 pm
The most ideal situation is...
1. Formal charge closest to zero
2. central atom w/o charge
3. charges (if any) distributed as evenly as possible among atoms (2- vs 1- and 1-)
Hope this helps!