Drawing the Lewis Structure for H2CO

Viewing Notes:

  • There are a total of 12 valence electrons in the H2CO Lewis structure.
  • H2CO is also called Formaldehyde. H2CO is the simpliest example of the organic functional group called the Aldehydes.
  • Carbon (C) is the least electronegative atom and goes at the center of the H2CO Lewis structure.
  • With H2CO you'll need to form a double bond between one of the Oxygen atom and the Carbon atom to fill the octets and still use only the 12 valence electrons available for the molecule.

Transcript: This is the H2CO Lewis structure. We have a total of 12 valence electrons for this H2CO Lewis structure. We'll start by putting Carbon in the middle, and then Hydrogens always go on the outside, and then Oxygen will go up here. We have 12 valence electrons. We'll put 2 between atoms to form chemical bonds and then on the outside to fill the octet of the Oxygen. So we have 2, 4, 6, 8, 10, and 12.

At this point, everything has a full outer shell except Carbon, which only has six valence electrons. We can take these 2 valence electrons from Oxygen and share them to form a double bond. Now the Oxygen has 8 valence electrons, still has 8, but the Carbon has 8. Then the Hydrogens, they only need 2 for a full outer shell, so they're OK. So in our Lewis structure for H2CO, we've completed the octets for each of the atoms, and we've used only 12 valence electrons.

One thing to note: whenever you see the term, "aldehyde", you have a very specific functional group. Aldehydes have a Hydrogen attached to a Carbon with a double bonded Oxygen on the Carbon. This R means the rest of the molecule. Formaldehyde is the simplest aldehyde. We have our double-bonded Oxygen and our Hydrogen, and then we just have another Hydrogen out here for the rest of the molecule.

So that's the Lewis structure for H2CO. This is Dr. B., and thanks for watching.