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In the video on solubility, I draw little pictures of sodium

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and chloride ions when sodium chloride dissolves or

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disassociates into water.

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This is sodium and this is chloride.

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And my simple brain, when I looked at it, I said, OK, how

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should I draw these things?

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I said, well, they're in the same period, and sodium is a

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Group 1 element.

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It's an alkali metal, while chlorine is a halogen, so

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chlorine's going to have a smaller atomic radius.

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And the logic there, just to review from the atomic table

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trends, is that both of their valence electrons are in the

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third shell.

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Sodium only has 11 protons pulling in the center.

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It has 11 in the center, and it has only one electron out

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there in its valence shell.

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So the attraction isn't as strong as the case of

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chlorine, which has 17 protons in the center.

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Although it has more valence electrons-- it has 7 of them--

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these protons are going to have a stronger

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attraction on them.

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So if you just look at the trend in the periodic table,

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you'd expect the sodium neutral atom to be bigger than

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the chlorine neutral atom.

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Because this guy has more protons pulling everything in.

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And that's how I drew the ions in that video.

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I said, oh, when I disassociate in water, I'll

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have a big sodium ion and a smaller chlorine

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ion, which is incorrect.

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Because think about-- and this was pointed out to me by one

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of the viewers, and they're correct, and I should have

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realized it.

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What happens when you ionize these things?

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This guy will lose an electron, right?

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He gives the electron to this guy.

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So his electron configuration is actually going to look a

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lot more like neon.

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He now will have no electrons in that third shell, in the

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third energy state.

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So now he's going to have an atomic radius that's actually

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much more similar to neon here, right?

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Because he's going to have filled up the second shelf.

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So actually, the sodium ion, this is completely incorrect.

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The sodium ion is going to have an atomic radius not that

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different than neon.

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Actually, it will be even a little smaller than neon

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because it has the same electron configuration, but it

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has one more proton.

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So the sodium ion is actually going to be smaller.

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Because it gets rid of the electron in that third shell,

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and the chlorine cation, gained an electron, so it has

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completely completed its third shell.

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So here you have where the chlorine ion

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is going to be bigger.

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So in that solubility video, I should've actually switched

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the places between the sodium and the

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chlorine, at least in size-wise.

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And, of course, I showed how they disassociate in water,

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and this would be attracted to the oxygen end of the water,

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and you have the hydrogen end and all that.

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But you can watch the solubility video for that.

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It doesn't change the real takeaway from the video.

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But I think this is a really interesting point that it

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brings up, that when you ionize these neutral atoms, it

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can significantly change, especially significantly

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change their relative atomic sizes.

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Anyway, hopefully, you found that interesting.

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