Periodic Trend: Ionization Energy

now ionization energy is the energy absorbed to remove an electron from a gaseous atom or ion based on position in killing jewels? Now we're going to say, Here we have nitrogen in its gashes state. We need to remove its electron. When I remove its electron, it becomes positively charged, and here we would illustrate the electron that's been moved by placing it also as a product. We said energy is absorbed, so we're taking in energy. We're gaining energy, so ionization energy will always be a value that's greater than zero. It will be a positive number now what? We also need to realize that since we're absorbing energy, oftentimes you'll hear this being called an Indo thermic reaction. In these reactions, energy is absorbed in order to break a bond. Here, we're breaking the connection of the electron to the element. Also, what we need to realize here is that ionization energy equals the potential energy off a given electron. Later on, we'll try to connect this whole idea of potential energy toe ionization energy. But for now, just realize we're moving an electron from a gaseous ion or Adam to create a mawr positively charged species

in terms of ionization energy. The periodic trend is ionization. Energy will increase as we're moving from left to right across a period and upper group. So as we're heading towards the upper right corner of the periodic table, ionization energy goes up here. If we take a look, we can see that the one with lowest ionization energy is Francie um, which makes the most sense because it's on the exact opposite, um, pattern of the periodic trend. And we can see here that the one with the highest is helium. It's to the most top right corner of the periodic table. Now, of course, there's gonna be a little bit of, um, some exceptions to this trend. We'll go into further detail about them. You'll notice here that nitrogen has a lower, higher ionization energy than oxygen. You also notice here that beryllium has, ah higher ionization energy than boron. There are other little subtle exceptions, but these four elements are the most commonly discussed when it comes to exceptions in ionization energy. So just realize that overall, as we head to the top right corner of the periodic table, ionization energy goes up

here, it says. Which of the following Adams has the smallest ionization energy. Remember, the general trend is as we're heading towards the top right corner, your ionization energy should be increasing. So if we take a look, we have phosphorus. We have flooring, potassium, chromium and bro me. We want the smallest ionization energy, so we're looking for something that's closer to the left side and lower down for the periodic table. Out of the choices presented, the one that fits that definition the best is potassium. It's the one most to the left and lowest down in terms of the periodic table and therefore to have the smallest ionization energy.

now, when it comes to exceptions in ionization energy, one of them, we can say, is when in the same period or, oh, Group 68 elements have a lower ionization energy than Group 58 Element. The explanation is that piece of shell orbital's are most stable when half filled or totally filled with electrons. If we look here, we have nitrogen versus oxygen. Oxygen is more to the right of the periodic table, so you would assume it should have a higher ionization energy. But in fact it doesn't. The reason is here. Nitrogen is already in a stable state. It's P orbital's are half filled, right. We have three electrons here. When I remove one electron from nitrogen, it becomes helium to s to to p two, and now, as a result, my P orbital's are no longer half filled and therefore not as stable for oxygen. On the other hand, here it's almost half filled for the two p orbital's. But we have one too many electrons. Oxygen will be willing to give up its electron to become to us to to p three, and in that way becomes half filled for its P Orbital's and more stable. Since oxygen is freely willing to give up these, this electron less energy is required to remove it. That's why it's ionization. Energy would be lower than nitrogen. So remember P Orbital's are most stable when they're either half filled or totally filled.

now, another exception that exists with ionization energy has to do with the fact, then when in the same period row Group three A. Elements have a lower ionization energy than Group two elements. The reason here being that s sub shell orbital's are most stable, one totally filled. So the most common example for this is between beryllium and boron, boron ISMM or to the right of the periodic table. So you would expect it to have a higher ionization energy. But in fact, that's not true. Here. Beryllium is already in a stable state. It's as orbital electrons are completely filled in. So this orbital's totally filled in and it's very stable. That means if I come in and try to remove an electron, it becomes to s one. We're no longer in a stable state as we want. Remember, as orbital electrons are most stable when they're totally filled in born, on the other hand, is helium to us to to p one. If we could lose this one electron from two p, all we'll be left with is a two s two orbital, which is very stable. So that's what's gonna happen. So it becomes helium to s to once I remove that electron. And now I have an s set off orbital electrons that are totally filled in and therefore it's more stable. As a result, this means that boron has a lower ionization energy than beryllium.