Learn about Advanced Placement Chemistry, Chemical bond 5, in this comprehensive video by bannanaiscool.
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Rob Lederer: Do you think, however in ethane drawn here again we have the carbons, three Hybridize orbitals and one unhybridized orbital, here is the sigma bond here is the phi bond, here is the double bond. We think that these two orbital's now that they overlap and they have one electron end of these, so now they overlap and put 2 electrons in that bond. Do you think then that this orbital still have its same character and this one does truly, really just overlap and electrons are shared in overlap area probably not, so even hybridization doesn't really explain stuff really well no kidding. So we probably have this one hawking big orbital that actually contains the electrons in it. In the molecule, so we call it a molecular orbital a molecular orbital's actually help us to define not only were the electrons might be but look at this, that there was one orbital there and other next two orbital's. Well, each one will can hold two electrons so you know when these two come together and they are sharing two electrons really you could cram four electrons into that double now orbital, which is what the molecular orbital is. Molecular orbitals with there bonding and anti-bonding areas this is the bonding area were would you out electrons, now if you are trying to cram in here. You have to put them into positions that words in between the nuclear because you already got enough electrons here to cause two end repulsions. This molecular orbital can extend how to know lets say to the back of this carbon and each of this carbons so then you can put electrons into empty bonding positions which actually require more energy than putting them between the nuclei when the energy is lost, so here is what the energy level diagram might look like, when two elements come together to bond here is kind of a mini graph energy is going up that were you got the H2 there energy is going up and we got levels. Here is a low level of energy and here is the higher level of energy. Now let's take a hydrogen atom and a hydrogen atom and bring them together to bond them together. Now you know that hydrogen is 1S1 and here is hydrogen over here that is 1S1 as well. So, when they come together their orbitals are going to overlap from that molecular orbital and the electrons remember we get two electrons to form a bond. One electron and another electron are actually going to go into a low energy position to form a bond one electron from one combined with another electron from the another, now this level is filled with many electrons as we can have in this sigma bond of the one at 1S and so a low energy position is obtained when two hydrogen's come together energy is released, low energy position for H2 now look at. These are such a thing with H2 with the negative one charge well, how many electrons would that have? It would have three electrons total how do you account fro all that, if the two all atoms comes together two electrons are going to bond together being the bond and that's going to be in the sigma orbital's which are going to then hybridize. But then there is one electron left what is it goal, it can pull in between the two nuclei because now I got hydrogen here and hydrogen here you got already two electrons in their cram and the another one in there two many repulsions one spinning one by one spinning the other, and the other one is just turned in a whole lot. So the other one has to go into an anti-bonding orbital's somewhere else in the molecule and that empty bonding were goes a high energy type of orbital so it would go here but because we have in terms of the number of electrons in the bonding although which is two, we only have one of the anti-bonding orbital, which is one and then we divide by two because any orbital has two electrons in it. This gives you actually a number that is one half 2-1 is 1 divided by 2 is one half. It's positive one half and ladies and gentleman, when we take the number of bonding electrons hence attract the anti-bon