1. Draw the structure of cis-CH3CH=CHCH2CH3 showing the pi bond ...

Question

1. Draw the structure of cis-CH3CH=CHCH2CH3 showing the pi bond with its proper geometry.2. Draw the trans isomer, and circle the coplanar atoms. Are there still six?

Structure of trans-alkene with a methyl group and pi bond geometry.

Accepted Answer

Hey everyone, let's solve this problem. It says show the structure of cis cl ch double bonded to C C L ch two ch three with complete geometry around the double bond. Now by drawing the Transit steamer, compare the number of CO planer atoms in both. So first it's saying to draw both assists and trans. And then compare the number of co planer Adams. Well based on the word complainer, what do you think that means that their atoms in the same plane? Right. Co planer. So how do we know if atoms are in the same plane? Well if they're double bonded to each other, which is S. P two hybridized for carbons, then they will be in the same plane and the atoms that are directly attached to those. In this case, carbon sp two carbons will also be in the same plane. I'll show you and I'll give you a little analogy once we draw them out to show you how that works. So let's draw our Cis and trans. I summers and recall what CIS and trans means. So sis means our high priority groups are on the same side of the double bond. And you remember our high priority groups, we determined by atomic mass. Right? That's what johnny taught me and our trans I summer has those high priority groups on opposite sides of the double bond. So let's draw out our compounds. We have our two carbons double bond into each other and we're looking at when we say sides, we're looking on the say top and bottom of this double bond. So for the cIS compound are chlorine atoms are going to be our high priority groups. And those who go on the same side. And our first carbon has a hydrogen in our second carbon has an ethyl group which is two carbons. Right, Okay. And our trans compound, similar double bond except now our high priority chlorine groups will be on the opposite the opposite sides of that double bond. And then we have our hydrogen In CH two CH 3 R. S. O. Group. Okay. And this is our full bond line structure. But I'm going to show you the neat that's showing all the atoms. But our actual sorry bond line structure that we use in organic chemistry, we know doesn't show the carbons or hydrogen. We don't write out the carbons rather. So let's draw that. And our hydrogen would be over here invisible. And then we have our ethyl group, CH two ch three and our trans group, we have our chlorine zones and our ethyl group. Okay, so I just drew both. So you can see review how to compare those structures. Now we're looking at comparing the co planer atoms. Well, we said that we're looking at the atoms that are double bonded to each other. So we know we have they each have two. Okay. And the atoms that are directly bonded to those carbons. So the cIS compound has four atoms directly directly connected to those sp two hybridized carbons. And so does the trans iceman, right? That doesn't change, the only thing that changes is their orientation or which side they're on. So These compounds both have six co planer atoms. Okay, this is our sis compound, our trans compound. And when you look at the geometry, so the analogy that I was going to talk about is pretend like you are this structure, this double bond is your body and let's say that your shoulder is right here. Now usually if you have a good working shoulder you can raise your shoulder and you let's say this let's get visible, let's say this is your shoulder and this is your elbow. Now if you have a perfectly working arm and then this is your hand. Okay? So let's say you have a good working shoulder, good working elbow, you can raise your arm up by your shoulder. If you keep your elbow straight, you can raise your arm up and down and if you keep your shoulders straight and move along your elbow and rotate your arm, you can rotate your hand around in a circle by rotating your elbow right like in this direction. So think of this double bond, the carbon and the double bond is like your shoulder and it's rusty. It can't move right because it's in that double bond. But this sigma bond here will be able to rotate so you can picture that your hand or this end carbon will be able to draw a circle. If you if you attached an expo marker to it and you rotated this sigma bond over here in black, then you can draw a circle with that end carbon. And that shows that that end carbon is not going to be co planer. Right? So that's why only the atoms that are directly attached to the double bond will be co planer, not those external atoms. Okay, so I hope this video is helpful and thank you for watching. These are your final answers.

1. Draw the structure of cis-CH3CH=CHCH2CH3 showing the pi bond with its proper geometry.2. Draw the trans isomer, and circle the coplanar atoms. Are there still six?

Key Concepts

Cis-Trans Isomerism

Pi Bonds and Geometry

Coplanarity in Alkenes

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