Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Hemidol on November 06, 2009, 10:33:18 PM

Title: Sigma/pi bonding
Post by: Hemidol on November 06, 2009, 10:33:18 PM: Draw two equivalent resonance forms for nitric acid, HNO3. How many sigma bonds are there? How
many pi bonds?

The structures I imagine will look like...

O=N-O-H
||
O

with a net overall charge of 0... not sure where the charges on atoms would be.

I'm really confused about sigma and pi bonds...
Title: Re: Sigma/pi bonding
Post by: UG on November 06, 2009, 10:35:36 PM: You know how NO₃^- looks like? Add an H and you have yourself HNO₃
Title: Re: Sigma/pi bonding
Post by: blstrs on November 06, 2009, 11:17:20 PM: Most simply, every single bond is a sigma bond. Each additional shared pair between two atoms is a pi bond.
Title: Re: Sigma/pi bonding
Post by: Ranadeep on November 07, 2009, 09:22:40 PM: The structure you imagined contains oxygen with 4 bonds which i think is not possible and also all Oxygens are attached to Nitrogen and no Peroxy bonds : )

NO₃^- is Resonance Hybridized [PM me for Structure : ) ] .. and it accepts a H⁺ and it may be added to any O^- randomly .. Then you get the stricture Like ..

   OH
   /
   O<--N=O 1. nitrogen is SP² hybrdized,bonds in 120 with each other
   2. SP²-P Sigma Coordinate Covalent Bond
   3. SP₂-P , one Sigma and one Pi
   4. SP₂-P , bond with O^- which again bonded to h+

Browse for CO₃^-2 for similarity so that you can be more clear .. it accepts to 2H⁺ and forums H₂CO₃

Hope it Helped and i am correct : )
Title: Re: Sigma/pi bonding
Post by: Hemidol on November 08, 2009, 01:28:42 AM: AH I see now. Thus this structure will have a total of 4 sigma bonds and 1 pi bond (as the double bond can indeed be considered sigma)--correct?
Title: Re: Sigma/pi bonding
Post by: Ranadeep on November 10, 2009, 08:37:37 AM: Yeah 4 Sigma and 1 pi bond : ) .. yea a double bond = 1 Sigma + 1 Pi . : )