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  • - [Instructor] In a previous video,

  • we introduced ourselves to the idea of bonds between atoms,

  • and we talked about the types of bonds,

  • ionic, covalent

  • and metallic.

  • In this video we're going to dig a little bit deeper

  • and talk about the types of bonds

  • that are likely to be formed between different elements.

  • And to understand that, I'm going to introduce

  • a broad classification of the elements,

  • and in general, we're just going to think about things

  • as metals and as nonmetals.

  • So before I even point out on the periodic table of elements

  • what are the metals and what are the nonmetals

  • and maybe what are the ones that are in between,

  • what are the properties of metals?

  • Well, generally speaking, they conduct electricity.

  • Conduct electricity.

  • They tend to be malleable, which is just a fancy way

  • of saying that you can bend them without breaking.

  • And generally speaking, and there's exceptions to this,

  • they are solid at room temperature.

  • So I'll say solid at room temperature.

  • Now what do you think the properties

  • of nonmetals are going to be?

  • Well generally speaking,

  • they're going to be the opposite of this.

  • Nonmetals, generally speaking,

  • at room temperature are often not solid,

  • they're often times gasses.

  • They are not going to conduct electricity well.

  • Now when you look at a periodic table of elements,

  • how do you divide the metals from the nonmetals?

  • Well that's what this little scratchy yellow line

  • I'm drawing is trying to indicate.

  • So everything above and to the right of this yellow line

  • is a nonmetal and if you look at the color code

  • from the folks who made this periodic table of elements,

  • everything in this yellow color that we have here,

  • so hydrogen and carbon and nitrogen

  • and oxygen and fluorine, chlorine, I could keep going,

  • these are all nonmetals.

  • And it is the case that generally speaking

  • at room temperature, they will be in a gas form

  • and they will not conduct electricity well.

  • These things in blue we've talked about in other videos,

  • these are the noble gasses.

  • So these are also nonmetals.

  • The people who made this periodic table of elements

  • put them in their own color

  • 'cause then you could view them as a subclass of nonmetals

  • and they tend to be very inert,

  • they don't interact with other things.

  • They don't tend to form any of these bonds.

  • Now everything else, you can consider

  • in some form to be a metal

  • and the reason why this periodic table of elements

  • has different colors is that there's subclassifications

  • of the metals

  • but generally speaking, all of these things

  • that you see right over here

  • below this scratchy yellow line

  • have the properties, generally speaking,

  • of conducting electricity, being malleable,

  • being solid at room temperature.

  • And these things that straddle

  • this yellow line right over here,

  • these things that are in this kind

  • of bluish-green kind of color,

  • these are sometimes viewed as metalloids

  • because they have some properties of metals

  • and some properties of nonmetals.

  • But generally speaking, if you know whether

  • the things reacting are metals or nonmetals,

  • you can oftentimes predict what type of bond

  • is going to form.

  • So for example, if I have a bond between a metal,

  • a metal and a nonmetal, and a nonmetal,

  • what type of bond do you think is going to form?

  • Well when you bond between a net metal

  • and a nonmetal, and we saw an example of that

  • in that first video on bonding,

  • say a metal like sodium, and then a nonmetal like chlorine,

  • we saw that that chlorine will swipe an electron,

  • the sodium might lose one,

  • then the chlorine atom becomes a chloride anion,

  • and then the sodium atom becomes a sodium cation

  • and then they become attracted to each other

  • and then you form an ionic bond.

  • So this tends to form ionic bonds.

  • Now what if you were to have a nonmetal with a nonmetal?

  • Nonmetal times two,

  • so two nonmetals bind,

  • bound, I'm having trouble saying it,

  • two nonmetals bonding to each other.

  • What do you think is going to happen?

  • Well we saw as an example in that first video

  • where we say well what happens if oxygen bonds to oxygen?

  • Well we saw that was a covalent bond

  • and that is generally the case

  • when you have two nonmetals form bonds, it is covalent.

  • And then last but not least,

  • and this might be the most obvious one of them all,

  • what do you think happens when you have

  • two metals forming a bond?

  • Well you can imagine that will be a metallic bond

  • where they contribute electrons to this kind

  • of sea of electrons and that's what makes them

  • conduct electricity so well and malleable.

  • So I'll leave you there.

  • There are exceptions to everything I just talked about

  • but generally speaking,

  • these notions will serve you well,

  • especially in an introductory chemistry class.

- [Instructor] In a previous video,

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B1 中級

結合の種類を予測する(金属と非金属)|AP化学|カーンアカデミー (Predicting bond type (metals vs. nonmetals) | AP Chemistry | Khan Academy)

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    林宜悉 に公開 2021 年 01 月 14 日
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