Now we're going to draw the lewis down structure for our formaldehyde. So our first step is to count the number of balanced electrons. Balanced electrons, once again, of those electrons that come from the outermost shells of our atoms. So oxygen has six valence electrons, carbon has four valence electrons, and h has one each. We have two h, and so two valence electrons come from our two HS. So we have a total of twelve balanced electrons.