Drawing the Lewis Structure for HSO3-

Viewing Notes:

  • In HSO3- Lewis structure Sulfur is least electron electronegative atom and goes in the center of the Lewis structure.
  • For the Lewis structure for HSO3- you should take formal charges into account to find the best Lewis structure for the molecule. Also note that you should put the HSO4- Lewis structure in brackets with as 1- on the outside to show that it is an ion with a negative one charge.
  • In the Lewis structure for HSO3- there are a total of 26 valence electrons.

Transcript: This is the HSO3- Lewis structure. When we see the H out in front, we know that it's going to be attached to the outside of one of these Oxygens when we draw the Lewis structure. We'll put the Sulfur in the middle--it's the least electronegative. Oxygens around it, three of them; and then that Hydrogen we said would go on the outside of one of the Oxygens. For the HSO3- Lewis structure, we have a total of 26 valence electrons. We'll put 2 between atoms to form chemical bonds, we've used 8, and then around the Oxygens to fill their octets. 10, 12, and 24. So we've used 24. We have 26. We'll put the last 2 on the central atom, the Sulfur.

We've used all the valence electrons. At this point, the Sulfur has 8 valence electrons. The Oxygens each have 8, so their octets are full. Hydrogen has 2, so its outer shell is full, as well. So this looks like a pretty good structure. However, when you look at the periodic table, Sulfur is in period 3. That means it can hold more than 8 valence electrons. So we really want to look at the formal charges here. When we calculate the formal charges, we see that the Sulfur has a +1, and then these Oxygens each here have a -1. We'd like our formal charges to be as close to zero as possible.

So what we can do is take 2 valence electrons here and share them in the center to form a double bond. When we do that, the formal charge on the Oxygen changes to zero, and the Sulfur goes to zero. So now we have a -1 here, but we're going to leave that because it is a negative ion. So that makes this the most stable Lewis structure for HSO3-. Since it is an ion, we'll need to put brackets around it and a negative charge.

So that's the Lewis structure for HSO3-. This is Dr. B., and thanks for watching.