Sketch the bonding and antibonding molecular orbitals that result from linear combinations of the 2p_z atomic orbitals in a homonuclear diatomic molecule. (The 2p_z orbitals are those whose lobes are oriented perpendicular to the bonding axis.) How do these molecular orbitals differ from those obtained from linear combinations of the 2p_y atomic orbitals? (The 2p_y orbitals are also oriented perpendicular to the bonding axis, but also perpendicular to the 2p_z orbitals.)

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hey everyone today we're dealing with molecular orbital's specifically were asked to draw the bonding and anti bonding molecular orbital that form As a result of interactions between two p orbital's either along the inter nuclear axis or perpendicular to the nuclear winter nuclear access. So before actually drawing them out, I'd really quickly just like to review that P overhauls can be either horizontal or vertical and they will look like this sort of like two balloons tied to each other at the ends. And I would also like to mention that bonding and anti bonding molecular orbital seems sort of counterintuitive but it bears mention that The interaction between Orbital's aren't just on paper they're happening in space. They're happening in three dimensions. So 4 2 orbital's to interact properly. They need to be aligned properly and need to be in the optimal position to interact and bond. It's when this doesn't happen it's that probability of it not happening that we see are anti bonding molecular orbital. Is the probability of it bonding that we see in our bonding molecular orbital with this in mind. Let's dove into the question. Let's start with part A. Were the atomic orbital's the atomic orbital's R. two p. S are aligned along the inter nuclear axis. So they will be oriented something like this. So the interaction only happens between one of the two lobes on each of the p orbital's. So because it's only a single lobe interaction, we will get sigma molecular orbital's let's try this out. Starting with the anti bonding because it would be a destructive interference and it looks something like this? No, down the center and this is sigma anti bonding to p Meanwhile the bonding would be the exact opposite because now they're actually bonding. So we'll end up with something like this where the lobes interact and the outermost lobes will look a little smaller. But but now we can see that physically the orbital's have bonded along the inter nuclear axis. So this is our sigma bonding, we can tell that it's our bonding orbital because I'm not adding an asterisk next to it, A sigma bonding orbital. So that's that. Let's take a look at part B Now now the orbital's are oriented perpendicular to the inter nuclear axis. In other words, they are vertical like. So and because they're vertical, we can now see that the interactions that will take place if they do are actually occurring between all of the lobes, both lobes of one orbital are interacting with both lobes of the other orbital. So it's a double lobe interactions. So we will end up with pie molecular orbital's looking at this in more detail. The pie anti bonding orbital. Well, look something like this and let's draw our node, we can see it almost shy away from each other. They won't interact. There will be no real constructive bonding happening here. They are trying to not interact. It's the probability of them not interacting and not bonding. Meanwhile, if they are to bond it would look more like this as our pi bonding orbital. So the key takeaway to understand from this is that or is the concept that anti bonding and bonding molecular orbital's are essentially counter active to each other, but represent how the orbital's require the proper configuration in space to actually bond with each other. And that if the there's only one lobe interacting, if there's only single lobe interaction, you will get sigma, you will get sigma molecular orbital's and if there's double lobe interaction then you will get pi molecular orbital.

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Key Concepts

Molecular Orbitals

Linear Combination of Atomic Orbitals (LCAO)

Orbital Orientation and Symmetry