MO Theory: Bond Order

molecular orbital diagrams can be used to determine the bond order of a molecule. Now, bond order itself is just a measurement of the number of electrons involved in bonds between two elements. We're going to stay here. A bond order of greater than zero means that the compound is stable and it exists. And we can also say that as the bond order increases the stability and strength of a bond also increases. Now remember there is an inverse relationship between the strengthening of the bond and the length of a bond. So if your strength is increasing, that means that the length of your bond is decreasing. Now we're also going to say that a bond order of zero means that the compound is unstable and it doesn't exist now. How exactly do we calculate our bond order? Well, we set up a molecular orbital diagram and we distribute our electrons within the bonding molecular orbital's and the anti bonding molecular orbital. And once we do this we can use the bond order formula. And here it says that the bond order equals half your bonding electrons. So those electrons found within molecular bonding orbital's minus your anti bonding electrons. These are your electrons that are found within your anti bonding molecular orbital. So again, once you set up your M. O diagram, you'd use that to help fill in this bond order formula to find the bond order of any particular molecule

determine the bond order of the N. O minus. I'll So here remember we're going to set up our molecular orbital diagram and will be based on the less electro negative element nitrogen is less electro negative than oxygen. So we're gonna use the molecular orbital diagram for nitrogen to set that up. We're gonna have here sigma to us, Sigma star to us. Then we're going to have pi to peep And then we're gonna have here σ two p. Then we're gonna have here pi star to pee and then finally we're gonna have up here sigma star to pee. Now if we take a look here nitrogen in Group five A. So it has five valence electrons, oxygen is in Group six A. So it has six valence electrons and then minus one means we've gained an additional electrons. So that's gonna be another electron on top. So this comes out to 12 valence electrons. So we start filling this in. So it be one too 56, 7, 8, 9, 10, 11 and 12. So we fill this in. And remember that the bond order formula. So bond order we're gonna bring it to be oh equals half of your bonding electrons minus your anti bonding electrons. So here we say half of so you're bonding electrons are 2468. So we have eight minus your anti bonding ones are the ones with the stars. So that's going to be two four anti bonding. So that's 8 -4 which is 44 times a half is equal to two. So the bond order here for this particular molecule will be too.

now recall that the bond order can determine how many bonds formed between two elements in a compound. And if we have a visual representation of our molecule, we can look at the connections between two elements and simply determine the bond order from that. So if we look at a molecule and we see a single bond between two elements, that means the bond order between them would be one. If we see a double bond between two elements, then their bond order would be to. So if I gave you, for example, here I give you carbon triple bonded to nitrogen, we see a triple bond there. So the body order would simply be three. So again we can calculate bond order by setting up a molecular orbital diagram and then figuring out the number of bonding and anti bonding electrons. Or if they give you the actual lewis dot structure of a molecule, you can look at the bond between the two elements and simply say what the bond order is from that as well.

using Ml theory and bond order determine the number of bonds connecting the nitrogen atoms within the end to two minus ion. Alright, so remember we said that if you have a single bond, it's one. If it's double bond it's too here though, we don't have an actual visualization of the bond between the two nitrogen. So we're gonna have to use our M. O. Diagram since we're dealing with nitrogen. Remember that would be what sigma to us. Sigma star to us, pi two P sigma to pete pi star to pee and then finally sigma star to pee here, nitrogen group five days what has five valence electrons and there are two nitrogen. So that's five times two which is 10. And then we have an additional two electrons so add to two, this is 12. So all we gotta do now is fill in those electrons 12, aN:aN:000NaN 3456789, 10, 11. And then 12. And then remember here bond order which we're gonna abbreviate his B. O. Equals half of your bonding electrons. So you're bonding electrons would be too 468. So you have eight bonding electrons minus your anti bonding electrons, the ones with the star. So too four. So we do 8 -4, which is four times a half gives me too. So the bond order between the two nitrogen would be too and if we wanted, if I wanted to show you what this would look like it looks like this. This is what the ion actually looks like. And we can clearly see that there's a double bond between the nitrogen. So this visualization is definitely reinforced by the fact that we found a bond order of two. So that means there's a double bond between the two nitrogen, right? So we'd say that determine the number of bonds connecting the two nitrogen would say that they're connected by a double bond.