Chemical Bonding: HCN Lewis Structure

Drawing the Lewis Structure for HCN

Viewing Notes:

• Make sure you put the correct atom at the center of the HCN molecule.
• With the Lewis Structure for HCN you’ll need to share more than one pair of electrons between the Carbon and the Nitrogen atoms.
• Be sure that you don't use more than the ten valence electrons available.

Transcript: For the HCN Lewis structure we have one valence electron for Hydrogen, we have four for Carbon, and we have five for Nitrogen, for a total of ten valence electrons for the HCN Lewis structure. We'll put the Carbon in the center, because it's less electronegative than the Nitrogen, and Hydrogens always go on the outside of Lewis structures. We have a total of ten valence electrons for the HCN Lewis structure. We'll put two between atoms to form chemical bonds, so we've used four, then we'll go around the Nitrogen, six, eight, and ten.

So when we look at the Lewis structure, Nitrogen had eight valence electrons, but the Carbon only has four. So we're going to need to move some valence electrons from the center to form a double bond with Carbon. Let's try and do that.

Now you can see that Nitrogen has eight valence electrons and Carbon has six. So let's move another pair to the center. So we're still using ten valence electrons for the HCN Lewis structure, but Nitrogen has an octet with eight valence electrons, Carbon has eight valence electrons, Hydrogen has only two but that's all it needs for a full outer shell.

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