Acrylonitrile 1C3H3N2 is a molecule that is polymerized to make carpets and fabrics. The connections between atoms are shown.

(d) Identify the shortest bond in the molecule.

Video transcript

welcome back everyone. A chemical called vinyl acetylene C four H four is used in the polymer industry. The relationships between atoms are displayed identify the molecules shortest bond. So we're going to begin by making sure that our structure is complete. So beginning by calculating total valence electrons, we see according to our formula that we have four carbon atoms and four hydrogen atoms. Recognized that on the periodic table, carbon is located in group four A Corresponding to four valence electrons. And because we know we have four atoms that would give us a total of 16 valence electrons, we multiply by our four atoms. Now moving on to our hydrogen atom, we see that on the periodic table. It's located in group one a corresponding to just one valence electron. and so multiplying this by our four hydrogen atoms according to our formula. This would give us a total of four electrons contributed from our hydrogen. And so adding this total up, we would have a total of 20 electrons for our Lewis structure. And so counting up what's used in the image. We have 24 because we recall that a bond is made up of two electrons. So 2468, 10, 12, 14 electrons used. Let's take that difference. And that would leave us with six electrons left over for our structure. And if we know we have six electrons left over and we know that hydrogen can only have one bond since it only has one valence electron, those remaining electrons are likely just going to be bonds on our carbon atoms. And so if we have six electrons left over, we would have enough electrons left to make three bonds. So we're gonna need to add three bonds to our structure. What we next need to think of is bonding preference. And our octet rule. When it comes to carbon recall that carbon should have four bonds to have a full octet of eight electrons, hydrogen on the other hand follows the duet rule because it only has one bands electron, so it can only form one bond as its bonding preference. And so looking at our carbon atoms, specifically at carbon A. We only have two bonds as well as carbon B. And so we're going to need to fix that by adding a triple bond between carbon A. And B. Which would use up two of our three bonds that we can make. And now adding our third bond, we can see that for a full octet for carbon C and D. We're going to need to place a double bond between carbon C. And D. And that would use up our third bond that we can make using up all six of our electrons that are left over. And let's erase this. So now that we have our bonds added and we have a complete structure of our vinyl ceiling. We need to determine the shortest bond length. So we're going to be comparing between hybridization of our atoms to determine the shortest bond length. And we want to recall that when it comes to bond length, we can base that off of hybridization where sp corresponds to the shortest bond length where sp two has an even shorter bond length and then we have sp three hybridized atoms which should have the longest bond length. So again S. P. Corresponds to shortest bond length. S. P. Two is a little bit longer than sp and sp three would be the longest in bond length. So with this in mind we now want to look at our carbon atoms. Since that is what we are basing this answer off of and we can see that we have a triple bond between carbons A. And B. Where we would recognize that carbons A. And B. Are bonded to two atoms each, we have this carbon bonded to hydrogen and this other carbon carbon B. And then carbon B. Is bonded to carbon A. And carbon C. So two atoms. So because we have, and let's note this down, Carbon A. And carbon B Bonded to two Atoms and a triple bond. This would correspond to sp hybridization. So we can label that in for carbon A. S. S. P. And carbon B. S. Sp hybridized, meaning that so far we can say carbon A. And B. Have the shortest bond length because they have that triple bond. And now we would look at carbon C. And D. And determine their hybridization. So looking at carbons C. And carbon D. Based on their bonding, we have carbon C bonded to 1 to 3 other atoms and carbon di is bonded to 1 to 3 other atoms to. So we can note down that carbon C. And D. Are bonded 23 atoms and have a double bond. And so this is going to correspond to what we recognize as sp two hybridization. And so that means that the bond between carbon C. And D. Is a bit longer than our triple bond here, which has a much shorter length. So to complete this example, we would say that for a final answer because carbons A and B are sp hybridized, therefore they have the shortest bond. And so in summary carbons and be with their triple bond in our structure of final Celine corresponds to being the shortest bond. I hope that everything I explained was clear. If you have any questions, please leave them down below. What's highlighted in yellow is our final answer and I'll see everyone in the next video