Here it is to draw a structural formula for C2H6. Alright, so this molecule or compound has two carbons within it. We can show these two carbons bonding to one another. Now we have 6 hydrogens and two carbons. To keep things fair, each one can get three hydrogens apiece.
Now here this carbon would have 3 hydrogens and this one would have 3 hydrogens. This comes out to be our structural formula for C2H6, and in fact, this is the only structural formula we could draw. Remember, hydrogens can only make one bond, so we couldn't put any of them in the center, which means our two carbons must go in the center.
Carbon ideally wants to make four bonds by drawing it this way. They're all making four bonds, which means we cannot draw a double bond between them or a triple bond, because that would exceed the four bonds that carbon ideally wants to make, right? So this will represent our structural formula for C2H6.