Periodic Trend: Atomic Radius

by Jules Bruno
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So remember we said the general trend is as we had from left to right and up a group are atomic radius will decrease. So remember, as we had up a group, we say that the number of shells is going to decrease, so this causes a decrease in my atomic radius at the same time as removing from left to right of the periodic table. We're going to say that the shell number stays constant, but the number of electrons within that shell is increasing. This causes greater attraction to the nucleus which compresses the atomic radius a bit. So if we take a look here, we can see that typically we have our atomic radius given to us within PICO meters. We can see that hydrogen is pretty small at 37 PICO meters and we can see that as we head from hydrogen to helium, there's a small decrease. Now off course, there's gonna be exceptions here and there. Ah, lot of them happen within the pit here with our transition. Metals also realized that the last world, the periodic table, those elements because they're so large and so heavy because they've been synthesized in laboratories. There a little bit unstable, so we don't have definitive information on terms of their atomic radius. So we just leave them out and realize that we have our other transition metals that are below this, our inner transition metals. They have the same issue. So when it comes to atomic radius, these are the ones that are most important. You're not expected to memorize these numbers, so don't worry. You just need to understand the general trend. And it is as we head towards the top right corner of the periodic table. Atomic Radius, for the most part, will decrease. So keep that in mind when looking at questions dealing with atomic radius.