Tip:
Highlight text to annotate it
X
到目前为止 我们已经学习了一些 So far, we've learned a little bit
关于决定电子构型的知识 about determining electron configurations.
来看看能否用这些知识把周期表上的元素进行归类 Let's see if we can use that information to group elements
然后来推测一下 on the periodic table and then guess as to what they might do
它们是怎样和其它元素进行反应的 when they react with other elements.
现在让我们通过一些练习 So let's just figure out the electron configurations
来写出几个元素的电子构型 of a couple of elements just for a little bit of practice.
现在让我们来看看Li So, lithium, right there.
它看起来像什么呢 What does it look like?
这是Li的电子构型 Lithium's electron configuration.
第一层 1s2 You get the first shell, is 1s2.
有两个电子 Two electrons there.
然后是2s1 And then you have 2s1.
有时为了节省时间 为了标记 And sometimes, just to be quick, to get the notation,
你可以想象一下Li的电子构型 is you can imagine lithium's electron configuration
有一部分是跟He完全一样的 is the exact same thing as helium's electron configuration
这是He的电子构型 再加上2s1 -- this is helium's electron configuration-- plus the 2s1.
Li的电子构型也可以写作——用浅蓝色表示—— This could have also been written as-- do that in light blue
也可以写成[He]2s1 -- could also have been written as helium, 2s1.
这在本质上意味着Li的电子构型 Which essentially means that lithium's electron configuration
就跟我们之前写的 is exactly what you would have written
He的电子构型 for helium's electron configuration,
加上2s1 and then you'd have written 2s1.
你可以在很多地方用到 You could do that a bunch of times.
比如当我们想写出 Let's say if we wanted to figure out
Fe的电子构型时 the electron configuration of iron.
不是写出所有的亚层 Instead of going through the whole thing, you know,
比如先写1s2 接着2s2 然后2p6 it's 1s2, and then it's 2s2, and 2p6.
不需要写这些 你可以说 Instead of doing that whole thing, you could just say,
Fe有着跟其他元素同样电子结构的部分 OK, iron has the same electron configuration.
所以 Fe的电子结构是 So you could say iron's electron configuration
跟Ar的差不多 is the same thing as argon's.
有一部分跟Ar的电子构型一样 is the same thing as argon's electron configuration.
所以你可以把Ar写在方括号里 So I'll just put argon in brackets.
然后在后面写4s2 And then you get 4s2. 4s2.
然后是 1 2 3 4 5 6 And then you have one, two, three, four, five, six.
d6 So d6.
因此我们知道在d亚层 And we learned that when you're in the d subshell,
或者说在周期表的d区 or when you're in the d-block of the periodic table,
实际上是电子在回填到上一能层 you are actually backfilling the previous shell.
在第四周期里 So when we're in the fourth period,
其中d区中的元素 会去回填第三能层的电子 in the d-block, we're backfilling the third shell.
所以就是3d6 So 3d6.
有人就会问一个有趣的问题 And someone had asked-- and this is an interesting question
为什么会这样呢 -- why does it do that?
为什么不接着占据外面轨道呢 Why does it not just continue?
为什么电子不填充第四层的d轨道呢 Why doesn't it fill the fourth d shell?
我是这样想的——从直观上来讲 And the way I think about it-- and this is all intuition,
原子世界的事很多都是这样 and things at the atomic level really start to become,
仅是在一些方面不是直观的 on some levels, non-intuitive-- but the way
我个人是这么认为的 随着原子越来越大 I think about is as the atom grows larger and larger,
先前的轨道之间有了更多的间隙 there are more spaces between the previous orbitals.
举个例子 可以这么想象 For example, this is just how I visualize it.
第一能层是这样的 If my first shell looks like this.
s亚层是这样的 Let's say the s looks like this.
接着我把它切割掉 And then, if I just cut it out,
这就是p亚层 let's say the p's look like something like this.
这可看作是第二能层 This is maybe the second shell.
p亚层是这样的 The p's look like this.
然后电子接下来想填入的 And then the next place an electron might want to be
就是第三能层了对吗 might be in the third shell, right?
所以第三能层是这样的 So the third shell would be like this.
然后第三能层的p轨道被填满 And then you fill out the third p shell.
这只是一个直观的印象 This is just an intuition.
当然电子不真的是这样填充的 This isn't exactly what an electron would look like.
第三层的p轨道有可能类似于这样 Maybe the third p shell would look something like that.
看起来跟这个一样 Look something like that.
像这个一样 And then look something like that.
然后到了第四能层 And then you're in the fourth shell.
到了第四能层 So you're doing the fourth shell.
s亚层是这样的 The s subshell might look something like that.
电子不是继续填满下一个p轨道 And then instead of immediately starting the next p shell,
现在轮到了d区的元素 you're in the d-block now.
所以这是——让我做些标记——4s亚层 So this is-- let me just write some labels-- 4s.
这是3s亚层 This is 3s.
这是3p亚层 This is 3p.
这是2p层 This is 2p.
这是2s层 This is 2s.
1s在2s内层 And then 1s is inside of 2s.
所以不用考虑太多 So you don't have to worry about that too much.
但我对d轨道被回填原因的直观感觉 But my intuition behind why the d orbital gets backfilled
是因为原子变得越来越大了 is because now, as the atom gets larger and larger,
因为这些轨道之间存在间隙 you have these spaces in between the previous orbital.
现在 填满4s轨道后 So now, after filling the 4s subshell, or the 4s orbital
这是4s轨道 -- so this is 4s here-- out here,
又回去重新填3d轨道 we go back and we fill in the 3d orbital.
我们回去 So we're going back
去填这些间隙 and we're filling these spaces right here.
这里的能量比这里更低一些 So this is a lower energy state than this.
需要更多能量去塞电子 It takes more energy to cram an electron
回到3d亚层 回到那儿 back into the 3d shell, back there.
填完3d亚层之后 But then once you do that, now you're ready to
就会又回到了4p亚层 像这样 then go to the 4p shell, which might look something like this.
所以电子更倾向于到另一能层 So an electron would rather go to another shell,
也就是第四能层 而不是回填3d亚层 which is the fourth shell, rather than backfill the 3d shells.
一旦填完第四能层 But once it fills out the fourth shell,
电子也填补了其中的间隙 it fills in those spaces in between.
随着电子数越来越大 And as the electron gets bigger and bigger,
中间有越来越多的间隙 there's more and more spaces in between.
最后 当原子足够大时 So eventually, when the electron gets big enough,
d层之间会有间隙 there's going to be spaces between the d shells,
这就是d轨道 and that's where the d orbitals
这就是f轨道存在的地方 and that's where the f orbitals will go.
这就是我对于电子排布的猜想 That's my intuition behind its working.
很显然 我们到达了原子的标度 And obviously, when we're dealing at the atomic scale,
在我看来 我只能做到这些了 as far as I'm concerned, that's the best that I can do.
但可以这么说 But fair enough.
虽然这不是我想要说的 但这是个好问题 That's not what I want to do here, but that was a good question,
就是为什么在第四周期的元素 as to why do you go and backfill the third shell
电子要回填第三层呢 when we're in the fourth period?
好了 Fair enough.
这是写出Fe的电子构型的简单方法 This is an easy way to write iron's electron configuration.
我说这些就是为了说明 The reason why I'm doing all of this is to figure out
最外层的电子数是多少 how many electrons you have in the outermost shell.
对于Li来说 In the case of lithium,
最外层有一个电子 you have one electron in your outermost shell, right?
这是最外层轨道 This is your outermost shell right here.
有一个电子 You have one electron.
这里也是一样的 And you could have done the same thing right there.
而对于Fe来说 In the case of iron,
最外层有多少电子呢 how many electrons in the outermost shell?
记住 最外层是元素所在的周期 Remember, the outermost shell is the period you're in.
这是最外层 And this is the outermost shell.
虽然这些是能量更高的电子 So even though these are higher energy electrons--
需要更多的能量 it took more energy to backfill those
去填入较低的能级 into the lower energy shell--
这些是最外层的能层 it's these that are on the outside energy shell,
第四能层 是参与化学反应的一层 the fourth shell,that are going to be the ones that are reacting.
有多少个电子呢 And how many are there?
有两个 There are two.
这是一件很重要的事 And this is an important thing.
有两个 So there's two here.
最外层有两个电子 There's two on the outside shell here.
事实上 And actually, there's going to be two
每个粉色的元素最外层都有两个电子 for any of these in pink right here.
每一个处于d区的元素都是两个 会怎样呢 Any of the ones in the d-block, what happens?
不管在哪个周期 You fill whatever period you're in.
比如第五周期 Let's say that you're in period five here.
对吧 Right?
将有5s1 You're going to have 5s1.
5s2 5s2.
然后要回去 And then you're going to go back
填充第四层 and you're going to fill the 4d shell.
对吧 Right?
当说到外层有多少电子时 But in terms of how many electrons you have on the outside shell,
像这样在第五层 in this case the fifth shell,
将会看到两个电子 you are going to have two electrons.
所以所有这些都将会有 So all of these are going to have
两个电子在最外层 two electrons in their outermost shell.
这种情况下 最外层电子 In the case of these, the outermost electrons
将会是4s2 对吧 are going to be 4s2, right?
因为即使要回去填充3d轨道 Because then you go back and fill the 3d,
但最外层仍是4s2 but the outer ones are 4s2.
所以这个还是有两个电子在最外层 So this one also has two electrons in its outermost shell.
这一族有多少个呢 How many does this group have?
我刚刚用了一个词 And I've just used a word
我不记得我之前定义过没有 that I don't know if I've defined before,
族就是周期表中的列 but the group are the columns in the periodic table.
你们可以发现 它们都有相同的性质 And as you can see, they all have patterns to them.
第一族的每一个元素 Everything in this first group
最外层都有一个电子 has one electron in its outermost shell.
如果你不相信 看看H元素 If you don't believe me, look at hydrogen.
H的电子构型的1s1 Hydrogen's electron configuration is 1s1.
它的最外层是1s Its outermost shell is 1s.
其中有一个电子 It has one electron there.
对吧 Right?
这些都是这样 And that's true for all of these.
所有这些元素都有两个电子 All of these guys have two electrons
在最外层 in their outermost shell.
这些元素有相同的两个电子 These guys have those same two electrons.
我们可以这样认为 这两个电子在每个元素的最外层 We can view it that way, in their outermost shell,
之后电子就回填d亚层 but then they go and backfill the d shell.
但对于他们的最外层电子层来讲 But in terms of their outermost shell,
只有两个电子 only two electrons.
然后你一旦填完d亚层 就是一旦回填完 Than once you fill the d-block, or you go backfill,
对于第四周期元素 in the case of the fourth period,
回填的是3d亚层 you go and backfill the third d sub-orbital.
填满后再去填第四能层 Then you go back to filling the fourth shell again.
现在就是p区元素了对吗 Now the p block, right?
所以这个元素将有 So this one's going to have
三个电子在最外层 three electrons in its outside orbital.
或者说有三个价电子 Or you could say three valence electrons.
这个是4 5 6 7 8 This is four, five, six, seven, and eight.
让我再来说一个 以免你们不相信我 Let me do one more, just in case you don't believe me.
Sn的电子构型是什么呢? What's the electron configuration for Sn.
这是Se吗? 【译者注:他把锡说成硒了】 This is, what, selenium?
我不太确定 I'm not even sure.
就说Sn吧 But let's say Sn.
它的电子构型是什么呢 What's the electron configuration?
它和Kr构型有一样的地方 It's going to have the same electron configuration as krypton.
这就是Kr Yes, that element is krypton.
这就是那个元素 There is such an element.
Sn有跟Kr一样的部分 So it will have the same electron configuration as krypton.
所以我可以说出Kr的电子构型 So I could have figured out krypton's electron configuration
仅仅是通过整个元素周期表 just by going through the whole periodic table,
但这只是一个比较快的方法 but this is just a faster way of doing it.
前面跟Kr一样 然后是5s2 5s2 Same thing as krypton, and then it has 5s2. 5s2.
接着回填d区 Then it goes back and backfills the d-block.
有十个电子 So then there's 10 there.
就是4d10 So 4d10. 4d10.
然后开始填p区电子 And then it starts filling up the p-block
填第五能层的 in the fifth shell again.
5p2 So 5p2. 5p2.
所以它有几个价电子呢 So how many valence electrons does it have?
价电子 或者说是最外层电子 Valence electrons, or electrons in the outermost shell?
哪个是最外层 Well, what's the outermost shell?
是第五能层 It's the fifth shell.
所以是这些和这些 So these and these.
这些电子有更高的能量 These electrons have a higher energy state than that.
就需要更多一点的能量 It took a little bit more energy
把它们塞回之前的电子层 to cram them back into that previous shell
比起把它们放到s轨道要多 than it took to put these on the s orbital.
但当我们提到参与化学反应的电子 But if you talk about the electrons that will react,
这是我要强调的地方 and that's why I'm emphasizing these, these are the electrons
和其他原子反应的是电子 that are going to react with other atoms.
或者有时是跟其他电子反应 Or sometimes with just other electrons, even.
这个元素有四个外层电子 This one has four outside electrons.
你可以看到 And you see that right there.
四个外层电子 Four outside electrons.
由于外层电子是我们大部分时候 And since the outside electrons, for the most part,
会去关心的东西 are the ones that you're going to care about,
这儿有一个——我想你可以说 there's a-- I guess you could say,
一种可以只表示出外层电子的表示方法 a notation where you only draw the outermost electrons.
所以说 H 我们可以这样写 So, let's say, for hydrogen, you could write it like this.
你只写出了最外层电子 也就是价电子 Where you're only drawing the outermost, valence electrons.
价电子就是最外层电子 Valence electrons are just the outermost electrons.
你可以这样写 You could write it like that.
写成这样 You could write it like that.
但你可能会说 But this says, hey, I just have
H外围只有一个电子 one outside electron for hydrogen.
那Fe的应该怎么写呢 If I wanted to draw it for iron?
Fe 在这儿 怎么写呢 Iron, right here? How would I do that?
最外层有两个电子 I have two electrons in my outermost shell,
所以Fe可以这样写 so iron I could just do like this.
电子有配对的趋势 And electrons, they tend to be paired.
然后我想举一个例子 So if I have, let's say I wanted to take the example of,
如果这是Sn 这是Se if this is Sn, this is selenium.
让我们说说C Let me do carbon.
C最外层有四个电子 Carbon, I have four electrons in my outermost shell.
所以可以写成这样 So carbon I could write like this.
C 写成这样 Carbon, I could write like that.
如果不想让他们配对 Or if I didn't want to pair them,
理论上我也可以写成 in theory I could write them like that as well.
现在它们可以和其他物质反应了 And now they're ready to react with other things.
这一点告诉我 Now what does this tell me about, you know,
这个元素最外层有一个电子 this one has one electron in its outermost shell.
这些蓝色的 这些惰性气体 These blue, these noble gases--
让我们简单来介绍一下 and we'll talk a little bit about them in a second
它们最外层有八个电子 These have eight electrons in the outermost shell.
这些对我研究 How does that help me when I'm actually trying to
化学反应有什么帮助呢 figure out how things react?
这说明所有的原子 Well, it turns out that all atoms want to
都趋于最外层达到八个电子 have eight electrons in their outermost shell.
这是一个重要的数字 And that number is important.
八 Eight.
这些元素趋于形成八个电子 They want to have eight electrons
在最外层 in their outermost shell.
这是原子最稳定的构型 This is the most stable configuration for atoms.
我猜你们会说 某种程度上讲 Or I guess you could say, to some degree,
原子更稳定的能量状态 a better energy state for the atom.
为什么是八个电子呢 And why is it the number eight?
让我们想一想 Well, that's something to think about.
这是另一个基本的数字 This is another fundamental number
在自然界中 that just pops out of nature.
我刚刚想过一些 And I've thought a little bit about it.
这肯定跟原子的最外层有关 It must be something about the atoms in the outermost shell,
当有八个电子时 它们之间能很好地共存 when you have eight, they resonate well with each other.
它们之间不会相互妨碍 And they somehow don't get in the way of each other.
或者说不会互相排斥 Or don't want to push away from each other.
我也不知道原因 I don't know the answer to that.
坦白地讲 And frankly, if someone could really
如果真的有人可以准确地解释 answer the question of why eight,
为什么是八 他们在物理和化学领域 exactly why eight, they would make a good career
事业前景将一片大好 for themselves in physics or chemistry.
但这是已经在实验中证实了的 But through experimentation, it has been well established
原子有形成8个电子的趋势 that atoms want to have eight electrons
在最外层 in their outermost shell.
所以问题是 当你要研究 So the question is, if you're dealing with something like,
比方说当你要研究K时 let's say you're dealing with potassium.
对吧 Right?
K最外层有一个电子 Potassium has one electron in its outermost shell.
这时又有Cl的存在 Let's say you have stuff like chlorine,
最外层有七个电子 that has seven electrons in its outermost shell.
你觉得会发生什么呢 What do you think's going to happen
当你把K放在Cl旁边时 if you put some potassium near some chlorine?
会发生什么呢 What's going to happen?
把Cl会变成八电子结构 Well, what's the easiest way
最简单的方法是什么呢 for the chlorine to get eight electrons?
它最外层有七个电子 Well it has seven in its outermost shell.
什么方法最简单呢 What's the easiest way?
它是很想很想获得一个电子 Well, it'll want to gain an electron really, really badly.
对于K来说 最简单的方法 And what's the easiest way for potassium to have
使最外层有八个电子是什么呢 eight electrons in its outermost shell?
如果它失去一个电子 Well, if it lost that one electron,
他的最外层就有八个电子了对吗 then it will have eight electrons in its outermost shell, right?
它的最外层的电子层就不是第四能层了 Its outermost shell won't be the fourth shell anymore.
将是第三能层 It'll be the third shell.
它的第三能层将会有八个电子 But it'll have eight electrons in the third shell.
它的构型会像Ar一样 Its configuration will then look like argon
如果它失去那个电子 if it loses that one electron.
就会形成更稳定的状态 So it'll be a more stable state.
那么当你把Na放在Cl前面时 So if you put sodium in the presence of chlorine,
会发生什么呢? what's going to happen?
电子将会有很强的脱离Na的趋势 This electron wants to jump off of sodium real bad
这样Na的最外层就会有八个电子了 so that sodium can have eight electrons in its outermost shell,
电子构型像Ar一样 or have an electron configuration like argon.
而这个电子被Cl吸引过去 And that electron is going to jump to chlorine,
这时Cl就 and then chlorine will have
在最外层有八个电子 eight electrons in its outermost shell,
也会形成像Ar那样稳定的构型 and also have an electron configuration like argon.
然后你可以想象得到 这一族 And so, as you can imagine, this group right here,
也叫作碱金属 which are called the alkali metals.
我们可能会在下一个视频中 And we'll talk probably in the next video
解释为什么它们被叫作金属 why they're called metals.
这一族 碱金属 This group here, alkali metals.
他们中不包括H And they tend to exclude hydrogen,
我们将要介绍这点 and we'll talk about that.
这些碱金属有失去电子的趋势 These really want to give away electrons.
正因为如此 它们的化学性质非常活跃 And because of that, they're highly, highly reactive,
尤其是当它们处在这些元素前时 especially if you put them in the presence of these elements,
这些黄色的元素 these yellow elements right here,
它们被叫作卤素 which are called the halogens.
它们有很强地吸引电子的趋势 These really, really want to take electrons from other things,
因为它们只需要一个就可以达到八电子结构 because they just need one to get to eight.
它们想失去电子 They usually want to give away electrons,
因为它们只需要一个电子就可以达到八个 because they just have to give away one to get to eight.
至于为什么H And the reason why hydrogen, actually,
不属于碱金属 是因为 isn't included is because hydrogen doesn't want to
H原子没有像它们那么强的失去电子的趋势 give away its electron as bad as these guys.
想要达到八电子结构的这一规则 This rule that your outermost shell wants to get to eight,
对于所有元素都适用 that's true for everything
除了H和He except for hydrogen and helium.
H和He 因为它们只有一个电子层 Hydrogen and helium, just because they have one shell,
当它们有两个电子时就很开心了 they're happy with just two electrons.
确实对于H来说 它可以失去一个电子 And so with hydrogen, sure, it could lose an electron,
但它更乐意接受一个电子来达到稳定 but could just as easily gain an electron and be happy,
因为这样也可以填满第一能层 because it'll have a full first shell.
但对于其他碱金属来说 But all of these other ones, these alkali metals,
它们非常想失去电子 they want to give away electrons really bad.
当学化学的人谈论起金属的性质时 When people in chemistry talk about metallic nature,
他们实际上是在说 they're really talking about
它们失去电子的能力 how badly something wants to give away electrons.
好了 时间差不多了 Anyway, I'm all out of time now.
再下一个视频中 我们将 In the next video, we'll continue
继续探讨周期表中的族 discussing the groups in the periodic tables
和我们可从中获得的信息 and any trends we can ascertain from them.