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The balloons contain helium and oxygen so that they float around with the air currents.
VOA: special.2010.09.05
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z So, this is what we find the actual z effective is for an electron in the helium atom.
所以这就是我们得到了实际有效的,对于一个氦原子的电子。
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So let's take two cases of shielding if we're talking about, for example, the helium, a helium nucleus or a helium atom.
所以我们来对屏蔽举两个例子,如果我们在讨论氦，举例来说一个氦原子核或者氦原子。
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At first,the red men of Helium thought we were an attacking army.
VOA: special.2010.07.31
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It could be hydrogen, it could be helium plus, it could be lithium double plus and so on.
它可能是氢，可能是带一个正电荷的氦，也可能是带两个正电荷的锂，等等。
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You can see huge helium balloons, bands and costumed marchers.
VOA: special.2011.04.08
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We use a liquid helium. And so in order to make a liquid helium, you can't take helium at room temperature and do this, because if you did, you would just heat it up, because the room temperature is above the inversion temperature, so Joule-Thomson would heat up the helium.
为了得到液氦,不能再常温,做这个实验,否则就是加热氦气，因为室温高于它的转变温度,所以焦耳-汤姆孙，实验会加热氦气。
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All right. Let's consider now the second extreme case, or extreme case b, b for our helium atom.
好的让我们现在来考虑,一下第二种极端案例，或者极端案例。
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Versus looking at, for example, helium or neon or argon, these are all inert gases, inert meaning essentially do not react, those were grouped together in the periodic table.
相反，他发现氦，氖，氩，都是惰性气体，惰性的意思是基本不参与化学反应，因此把它们放在周期表中的同一类里。
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He's trying to put eight electrons around helium, and it isn't working. But look down here.
他尝试把8个电子放在氦的周围，但那不行，但注意到这里。
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I would say with the aid of an energy level diagram explain the fact that helium is found as atomic gas and not molecular. How about this one?
我要说的是，在能级图的帮助下,可以解释氦气是单原子气体,而不是分子气体这一事实,那么这个呢？
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s2 And, in this case, I start with helium -is 1s2.
在这种情况心爱，氦开始的是。
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Alpha particles are these helium nuclei, and they are the result of radioactive decay.
阿尔法粒子是氦核，它们是放射性衰变的产物。
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Similarly we see as we go down the table, so as we're going from one row to the next row, so, for example, between helium and lithium, we see a drop; the same with neon to sodium, we see a drop here.
同样地，我们来看看沿着周期表往下走，当我们从一行到下一行时，比如，从氦到锂，我们看到了一个下落;,从氖到钠也一样，我们看到这里有个下落。
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Yeah, good. So, they're actually helium atoms, helium ions. And this wasn't really important for the studies, it didn't matter that didn't know what they are but it's nice to kind of know now - that we do know what they were using.
氦粒子，这对他们的研究并不重要,他们并不需要知道它是什么,但我们最好知道,他们当时用的是什么。
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He goes back and redoes the calculation, only in this case he says what I am going to do is I am going to redo the calculation for helium, but I am going to consider not just the mass of the electron but the reduced mass of the system.
他回去重新做了计算，仅在这种情况下他才会说说我将要,为氦重做计算，但我认为,不只是电子的质量,还有系统质量的减少量。
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We have a helium nucleus and one electron.
我们有一个氦核和一个电子。
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If helium loses on electron, what do we have?
如果氦原子失去了一个电子，我们得到了什么？
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So you need first to take the liquid helium and cool it below 53 degrees Kelvin before you can do the Joule-Thomson to cool it even further to make liquid helium.
我们首先需要,把温度江都53k一下,然后利用焦耳-汤姆孙实验,来继续冷却它。
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Whatever the n number is, with the exception of helium, helium is the oddity because there's only two elements in n equals one shell.
无论n是多少，除了氦之外，氦是个特例,因为只有两个元素,在n为1的这一层。
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And He2 plus is observed in helium plasmas at high pressure, He2 but not neutral He2.
因此He2+能在高压的氦气等离子体中,被观察到，而不是中性的。
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You take your room temperature liquid helium and you cool it with liquid nitrogen to 77 degrees Kelvin, the new, you're not quite there yet 77k unfortunately right? Then you take hydrogen you cool it would liquid nitrogen to 77, then you can use your hydrogen gas.
首先要有常温的氦气,拿液氮把它冷却到77k，那个新来的7,你不坐在那儿，对吧？,然后用液氮把氢气降温到,然后就可以使用这个氢气了，想要用氢气来做焦耳-汤姆孙实验。
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And there he was able to identify the alpha particle as the helium nucleus.
他证实了,阿尔法粒子就是氦核。
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So, all that's left is the helium nucleus, two protons, two neutrons.
仅留下氦核，两个质子，两个中子。
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If you think about what happens when we go from hydrogen to helium, now instead of one electron, we have to describe two electrons, so now we have six position variables that we need to plug into our Schrodinger equation.
如果你们考虑,当我们从氢到氦会发生些什么，现在我们不是要描述一个电子，我们将要描述两个电子，所有我们现在将有6个位置变量,需要加入至薛定谔方程。
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So what is the charge on a helium nucleus?
那么氦原子核的电荷量是多少呢？
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So, helium plus is a one electron system.
所以氦正离子是一个单电子系统。
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It's helium denuded of both of its electrons.
即氦气脱去外层的电子。
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Well, this is isoelectronic with helium, right, and so is this, isoelectronic with helium.
而且这是He的等电子体，对吧，这就是He的等电子体。
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If we look at n equals one, here is n equals one, hydrogen and helium.
先看n等于1的情况，这里有个n等于1的例子，氢和氦。
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