A potential replacement for the chlorofluorocarbon refrigerants that harm the Earth's protective ozone layer is a compound called E143a, or trifluoromethyl methyl ether, F3COCH3. Draw an electron-dot structure for F3COCH3, and predict the geometry around both the carbons and the oxygen.

Video transcript

Hello. Everyone in this video. We're given this molecule here. What we want to do is find the lowest structure of this molecule and determine the geometry of auction and carbon items in this molecule. So we're given the formula of this molecule being C three H four, F 40. So we'll go ahead and use that to go ahead and calculate the number of valence electrons in this molecule. So for carbon carbon and group 48. So we have four valence electrons per atom in this molecule, we have three of those carbon atoms. So four times three gives those 12 total valence electrons from carbon. So we do the exact same thing for the other atoms. So for hydrogen is in group one aim. So we have one valence electron per atom here in this molecule we have a total of four hydrogen atoms. So one times four is four. Next for flooring It's in group 78. So we have some advanced electron per atom. We have four foreign atoms here. So seven times four is 28. And lastly for oxygen is in group six a. So we have six bands electrons per atom in this molecule. We only have one oxygen atom. So six times one gives us six. So if we take these some of this we get a total of 50 fans electrons in this molecule. So then drawing the Lewis structure. So we have a carbon carbon Bond here and then we have our four florian Adams. Then we have an auction because we have a ether here. So it has to be in the middle like so and then we have a methyl group at the end and metal group has three hydrogen atoms. The last one has to be on the left side here. So we know that carbon likes to be the central atom and also likes to have four bonds. So it's placed there and their auction likes to have two long pairs and two bonds. So it's located there and it's an either. So that gives us a big hint. Then our Florence here likes to have one bond and three long pairs. So we'll go ahead and add that to fulfill all the foreign atoms octet. Alright so we drew the lewis structure for this molecule here. Let's go ahead and circle that. Alright then we're being asked for the geometry of our carbon atoms and our auction atoms. So for carbon we take a look at the structure here. We said that they all have four electron groups. Let's take into account this one for example. So we have two connections to foreign one energy or electron group from hydrogen and then one from carbon. So a total of four electron groups. So if we have four electron groups. This shape then is going to be tetra Alright next for oxygen. We see here that well we just have one oxygen. So we just need to look at that as an example. So we have two atoms bonded and then we have two lone pairs. So two bonds and two lone pairs. This gives us a two or a geometry then of being bent, so we do have four electron groups, but two of them is going to be lone pairs. Therefore we have a bent structure. So this right here is going to be my final answer for this problem.