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Sulfite Ion example in class

Posted: Sat Nov 16, 2019 12:56 pm
by Amina Durrani 3G
In my notes I wrote that the bond angles of O-S-O are 106 degrees not 109.5 degrees, but why is this?

Re: Sulfite Ion example in class

Posted: Sat Nov 16, 2019 1:02 pm
by Angus Wu_4G
This is because the sulfur atom in the sulfite ion has a lone pair, and the lone pair present causes electron-electron repulsion, and therefore forces all the other bonds to be just slightly closer to each other. This is why the bond angle is 106, slightly less than the standard value of 109.5, which is the bond angle one would find in a tetrahedral with no lone pairs.

Re: Sulfite Ion example in class

Posted: Sat Nov 16, 2019 2:33 pm
by Robert Tran 1B
The lone pairs in the sulfite ion cause the bond angles to be slightly smaller because the electron-electron repulsion pushes the bonds closer together.

Re: Sulfite Ion example in class

Posted: Sat Nov 16, 2019 2:36 pm
by Rodrigo2J
Remember that in a sulfite ion there is a lone pair of electrons attached to the sulfur atom. Because lone pairs are more repulsive than atoms, they slightly change the bond angles between the atoms to slightly less than 109.5 degrees. We don't have know the exact bond angles, we just say that they are slightly less or slightly more than whatever the bond angle in question is. At least I think so.

Re: Sulfite Ion example in class

Posted: Sat Nov 16, 2019 3:22 pm
by AlyssaYeh_1B
Since lone pair electrons have stronger repulsion force, bonded atoms will be pushed further from it and gather closer to each other. This is more stable, since atom-atom repulsion is weaker than lone pair-atom repulsion. We don't need to memorize that the particular bond angle is 106 degrees. We only need to be able to understand that this structure has a lone pair, and thus the bond angles must be smaller than the expected tetrahedral bond angle (109.5)

Re: Sulfite Ion example in class

Posted: Sat Nov 16, 2019 3:43 pm
by Sadhana_Dicussion_4A
Since the sulfite ion has a lone pair, this causes a little more repulsion, causing the bond angles to be slightly less than 109 degrees.

Re: Sulfite Ion example in class

Posted: Sat Nov 16, 2019 3:48 pm
by Megan Ngai- 3B
The lone pair creates an electron electron repulsion. Therefore, it'll push the bonded atoms away from it but push them closer to each other.