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  • - [Instructor] In many videos

  • we have already talked about electron configuration

  • and now in this video

  • we're going to extend that understanding

  • by thinking about the electron configuration of ions.

  • These are going to be charged atoms.

  • Let's just start looking at some examples.

  • Let's say we are dealing with fluorine.

  • Now, we know what a neutral fluorine atom's

  • electron configuration would be.

  • In fact, if you want a little bit of practice,

  • try to pause this video

  • and think about what is the electron configuration

  • of a neutral fluorine atom?

  • All right, now let's work through this together.

  • A neutral fluorine atom has nine electrons,

  • and we could just use our Periodic Table of Elements.

  • So first, we're going to have two electrons in 1s.

  • So we'll have 1s two.

  • And then we're going to go to the second shell.

  • So then we go to 2s two.

  • So far we have filled in four electrons.

  • And next we got to the 2p sub-shell.

  • And we are going to have,

  • we're talking about a neutral fluorine,

  • we are going to have one two three four five electrons

  • in that 2p sub-shell.

  • So it's 2p five.

  • So if that's the electron configuration for fluorine,

  • what do you think the electron configuration

  • for fluoride would be?

  • This is just the anion that has one extra electron.

  • It is a negatively charged ion.

  • Pause this video and try to figure it out.

  • Well, here you're now going to have one extra electron.

  • The fluorine has nabbed an electron from someplace

  • and so where will that extra electron go?

  • Well our 2p sub-shell has space for one more electron.

  • So that's where it will go.

  • So the fluoride anion is going to have

  • an electron configuration of 1s two, 2s two, 2p,

  • now it's going to have an extra electron here, 2p six.

  • 2p six.

  • Now let's do another example.

  • Let's say we wanted to figure out the electron configuration

  • of a part positively charged calcium ion.

  • So calcium, let's make it two plus.

  • It has a positive charge of two.

  • You could do this as a neutral calcium

  • that has lost two electrons.

  • What would be its electron configuration?

  • Pause this video and try to figure that out.

  • All right, well one way to figure this out is

  • first we could figure out the electron configuration

  • of a neutral calcium atom

  • and then from that, we can take two

  • of the highest energy electrons away.

  • And so neutral calcium, you could view it,

  • actually let's do it in noble gas configuration.

  • Neutral calcium, the noble gas that comes

  • right before calcium is argon.

  • So it's going to have the electron configuration of argon

  • and then we are going to have two electrons

  • for that fourth shell.

  • It's going to fill in the 4s sub-shell.

  • And so we're going to have argon

  • and then we're going to have, let me do this in a new color,

  • let's call this 4s two.

  • Now what do you think is going to happen

  • if we were to lose two electrons?

  • Well those two electrons in that 4s sub-shell,

  • in the fourth shell, are gonna go away.

  • And so the electron configuration here

  • for calcium with a positive two charge,

  • this calcium cation, is going to be

  • the electron configuration of argon and no 4s two.

  • So it's actually going to have

  • the exact same electron configuration as argon.

  • So I will leave you there, just a couple of examples.

  • And I encourage you, if you're in the mood,

  • just pick any of these atoms, any of these elements,

  • and think about what would happen

  • if they gained or lost an electron

  • and what their electron configurations might be.

- [Instructor] In many videos

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B2 中上級

イオンの電子配置|原子の構造と性質|AP化学|カーンアカデミー (Electron configurations of ions | Atomic structure and properties | AP Chemistry | Khan Academy)

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    林宜悉 に公開 2021 年 01 月 14 日
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