Drawing the Lewis Structures for CH4OTranscript: For the CH4O Lewis structure, we have 14 valence electrons. So there are a number of ways to draw the Lewis structure for CH4O in which each of the atoms has a full outer shell and we only use 14 valence electrons. So I've drawn three here. When I look at these structures, my experience tells me that it's sort of odd to see a lone pair of electrons on those Carbon atoms. The Oxygen, I'm more used to seeing, but I don't see them so often on Carbon. So that makes me think that this structure may be the best Lewis structure. However, what I can do is calculate formal charges for each of the atoms to get more information about what might be the best Lewis structure. When I calculate the formal charges, this is what I find. Now, in the structure at the top, we have a negative for Carbon, and a plus two for Oxygen. Now I know Oxygen is more electronegative than Carbon, so this doesn't make sense to me. And I want my formal charges to be as close to zero as possible, so that structure doesn't make sense. The structure on the bottom's a little closer: the negative's on the Oxygen, the positive's on the Carbon; but still, I'd like my formal charges to be as close to zero as possible. The structure on the left is the one that really achieves that and really is the most appropriate Lewis structure for CH4O. So that's the Lewis structure for CH4O. This is Dr. B., and thanks for watching. |
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