Chemical Bonding: HSO₄^- Lewis Structure

Drawing the Lewis Structure for HSO₄^-

Viewing Notes:

• In HSO₄^- Lewis structure Sulfur is least electron electronegative atom and goes in the center of the Lewis structure.
• For the Lewis structure for HSO₄^- 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 HSO₄^- there are a total of 32 valence electrons.

Transcript: This is the HSO4- Lewis structure. When we see this H here in front of the Lewis structure with a polyatomic ion attached, we know that that Hydrogen atom is going to be attached to the outside of one of the Oxygens. So we'll put Sulfur in the center, that's the least electronegative. We have four Oxygens, we'll put them around the Sulfur atom, and then that Hydrogen will go on the outside of one of the Oxygens, like we said. For the HSO4- Lewis structure, we have a total of 32 valence electrons. That includes this one up here.

We'll put a pair of electrons between atoms to form chemical bonds--we've used 8 and 10. Then we'll go around and fill the octets for the Oxygen; 12, 14, and 32. So we've used all 32 valence electrons. Sulfur has 8 valence electrons, each of the Oxygens has an octet, and the Hydrogen, here, it has 2, so its outer shell is full. This looks like a really good Lewis structure for HSO4- but Sulfur is in period 3 on the periodic table, so it's a good idea to check the formal charges on each atom to make sure they're as close to zero as possible.

When we check the formal charges, we'll see that the Sulfur in the center has a +2 charge, where each of these Oxygens has a -1 charge. We'd like those formal charges to be closer to zero if possible. If we take a pair of electrons from the outside of the Oxygen and form a double bond with the Sulfur, that will change the formal charges so that this Oxygen now has a formal charge of 0 and the Sulfur has a charge of +1.

So let's do that again over here. By forming this other double bond here, we now have a formal charge of 0 on this Oxygen and the Sulfur is 0. That leaves us with a -1 formal charge on this Oxygen here. That makes sense because we have a negative charge up here. So the overall charge on this is -1, just like in the HSO4- chemical formula right here. One last thing we do need to do is put brackets around this, since it has a negative charge.

So this is the most stable Lewis structure for HSO4-. This is Dr. B., and thanks for watching.