Assign oxidation numbers to the underlined portion of each of the following: Na2S2O3 - S2O3 is the underlined portion for this compound.

Question

anonymous · Answer

The answer is -2 but I don't get why S2O3's oxidation number is -2...

anonymous · Answer

Ok. Both oxygen and sulfur are in the 16 group and carry a -2. Meaning their valence shells have 6 total electrons. As a polyatomic ion they are covalently bonded.

   . .        . .       . .
:  O  :    : S :   : O :

Forgive my horrid Lewis dot structures, but they are for the individual elements to illustrate the point. Draw out the structures for the whole ion and it should make some sense.

anonymous · Answer

I drew the Lewis dot structure, and then what?

anonymous · Answer

The lewis structure, will show that you have 5 atoms seeking to fill an octet. That octet is met by most of them and 2 open slots are left.

anonymous · Answer

Your structure should be similar to the one in this vid. http://www.youtube.com/watch?v=K7EAteDWxPQ