Drawing the Lewis Structure for HCOOH

Viewing Notes:

  • HCOOH is called Methanoic Acid or Formic Acid.
  • When you see COOH in a Lewis structure it is called a carboxylic acid functional group (see video for Lewis structure).
  • The carboxylic acid functional group is commonly seen in organic and biochemistry courses.
  • HCOOH is the simpliest structure containing a carboxylic acid functional group.
  • There are a total of 18 valence electrons for the HCOOH Lewis structure.

Transcript: This is the HCOOH Lewis structure: methanoic acid. The way it's written gives us quite a bit of information about HCOOH. First of all, we have an H in front, and that means it's going to be an acid. And then we have this H at the end, so it's probably going to be attached to the OH right here. So HCOOH: in this Lewis structure, we have a total of 18 valence electrons. Let's put the Carbon at the center; and we have this H here, let's put it out here; and then we have two Oxygens. So let's put an O and an H over here, and then I'll put the other Oxygen right there.

We'll put two electrons between atoms to form chemical bonds. So we've used 8 valence electrons there. And then let's go around the outer atoms and complete the octets. So we have 8, 10, 12, 14, 16, and 18 valence electrons. So we've used all 18 valence electrons. So, in this structure, the Oxygens have 8, so the octets are full, and the Hydrogens only need 2. Their outer shells are full, as well. The Carbon has 6 and it needs two more. We can take these two valence electrons here and move them to the center, sharing them to form a double bond. So now the Oxygen has 8, and the Carbon has 8.

So we've used 18 valence electrons and we have full outer shells for all the atoms in the HCOOH Lewis structure. So this is the correct Lewis structure for HCOOH. One last thing to note, though: whenever you see COOH written like that, that's going to be called a carboxylic acid functional group. You'll see it quite often when you're studying organic chemistry. It's a very important group. So if we draw it out, it'll look like this right here. You can see you have a double bond right here, that's your double bond there. You have your OH here, and here's your OH over here, with your Carbon right in the center.

It's likely you'll see the carboxylic acid functional group quite frequently if you go on in chemistry. At any rate, here's the Lewis structure for HCOOH. This is Dr. B., and thanks for watching.