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If dark matter particles exist, scientists say, they should be able to observe a small amount of light given off when they hit the nucleus of a xenon atom.
VOA: special.2009.07.21
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Let's look at the energetics of one of those electrons crashing into a hydrogen atom inside the gas tube.
我们一起来考察一下,其中的一个电子的能量,在阴极射线管中,撞击到氢原子上。
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Sometimes we have a very electronegative atom that's going to take more of its equal share of electron density.
有时候我们会有一个电负性很高的原子,它将会获取更多的共用电子密度。
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So, last date we were looking at some early taxonomy, and then on to a little bit more about the interior of the atom.
因此，最近我们了解了一下早期的分类法，以便加深,对原子内部的理解。
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Suppose we've got some sort of radioactive atom, which has a certain chance of decaying.
假定我们有某种放射性原子,它们以一定的几率衰变
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So we're going to feel a higher z effective in the case of the ion compared to the neutral atom.
因此，我们在离子中,会比在中性原子中感受到更高的有效核电量。
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Right, we had one from each atom, so that means we need a total of two in our molecular orbital.
对吧，每个原子有一个电子，这意味着在分子轨道里我们一共需要两个电子。
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Because what it tells is that we can figure out exactly what the radius of an electron and a nucleus are in a hydrogen atom.
我们可以,准确的算出,氢原子中,电子。
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He introduced the concept of electronegativity which was a measure, therefore, it is quantitative, of the atom's ability to attract electrons within a covalent bond and developed a scale of electronegativity.
他引入了电负性这一概念,一个反映着原子在成共价键时吸引电子的能力的数据标度，因此这是数量上的，在共价电子中,电子原子能吸引电子,并发展为一定规模的电负性。
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So if we're talking about the fourth excited state, and we talk instead about principle quantum numbers, what principle quantum number corresponds to the fourth excited state of a hydrogen atom.
如果我们说的是,第四激发态，我们用,主量子数来描述，哪个主量子数对应了,氢原子的第四激发态？
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And, that's a good thing to know because if you come out with an answer that's somewhere near the diameter of the universe and it's supposed to be the diameter of an atom, then you will know that you probably made a mistake.
这是我们需要知道的,因为当你做一道题得到的答案,是宇宙的直径,而正确答案是原子直径时，你能很快发现你的错误。
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It turns out, and we're going to get the idea of shielding, so it's not going to actually +18 feel that full plus 18, but it'll feel a whole lot more than it will just feel in terms of a hydrogen atom where we only have a nuclear charge of one.
结果是我们会有,屏蔽的想法,所以它不会是完整的，但是它会比原子核电荷量,吸引力要大很多,只有1的氢原子的。
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Furthermore, the electron has a very tiny mass in comparison to that of the overall atom.
进一步，电子的质量很小,相比于整个原子。
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We're going to be looking at the solutions to the Schrodinger equation for a hydrogen atom, and specifically we'll be looking at the binding energy of the electron to the nucleus.
我们将研究下氢原子薛定谔方程的解,特别是电子和核子的结合能,我们将研究这部分。
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So in terms of the first step of skeletal structure, this is actually going to be easier because we don't have a central atom, we just have carbon and nitrogen here.
对于第一步画出骨架，其实比刚才更容易,因为我们没有一个中心原子，我们这里只有碳和氮两个原子。
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In terms of where different atoms are in a molecule, if you have a hydrogen atom or a fluorine atom, you can pretty much guarantee they're always going to be terminal atoms.
对于不同原子在分子中的位置，如果你有一个氢原子或者一个氟原子，那你基本可以保证,它们总是最末端的原子。
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So you can think about how these 2 things combined are going to be electronegativity, which is a measure of how much an atom wants to pull electron density away from another atom.
因此你可以想象出,这两样性质合起来就是电负性，也就是一个度量，关于一个原子,有多希望把另一个原子的电子密度拉过来的。
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Right, this makes a lot of sense because if the entire atom was made up of nuclei, then we would have 100% probability of hitting one of these nuclei and having things bounce back.
因为如果整个原子,都是原子核，那我们就有100%概率,撞到一个原子核并被弹回来,所以如果我们。
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What I just spent many lectures discussing is the fact that we can not know how far away an electron is from the nucleus, so we can't actually know the radius of a certain atom.
我花了这么多课时所讨论的正是我们,不可能知道电子离原子核有多远这一事实，因此我们不可能知道某个原子的半径。
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So again, we should be able to check all of our formal charges and make sure they add up to 0, which they do, and that makes sense, because we have a neutral atom in terms of thionyl chloride.
因此同样地，我们可以检验一下,我们所有的形式电荷是否正确,确保它们加起来等于零，而它们确实是这样，这是合理的，因为亚硫酰氯是一个中性原子。
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I mean they take up a teeny bit but essentially when we're thinking about the set up of the atom, we don't have to account for them as using up a lot of the mass we're discussing.
所以我们可以假设电子没有质量,它们占据了，非常小的一部分,所以当我们考虑,原子的构造的时候,不用考虑它们的质量。
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If we want to talk about two hydrogen atoms, then we just need to double that, so that's going to be negative 2 6 2 4 kilojoules per mole that we're talking about in terms of a single hydrogen atom.
而要讨论两个氢原子，我们只需要把它乘以二，因此应该是负的，2624，千焦每摩尔,这就是单个的氢原子的情况。
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So, basically any time we have a really high positive number of electron affinity, it means that that atom or ion really wants to gain another electron, and it will be very stable and happy if it does so.
因此，基本上无论什么时候,只要我们有一个很大的正的电子亲和能，这就意味着这个原子,或离子非常希望得到一个电子，如果它得到了，会变得更稳定更开心。
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So, this allows us to look at a bunch of different atoms, of course, limited to the fact that it has to be a 1 electron atom.
所以这让我们可以研究很多原子，只要它们都只有一个电子。
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So it's just a measure of how much does one given atom want to pull away electron density from, let's say, an adjacent atom.
因此，它就是度量一个给定原子有多么,想把电子密度拉过来，可以说，从相邻的一个原子那里。
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n l m s Once we have chosen a certain mix of n, l, m and s, it is used once for that particular atom.
一旦我们选定了一组量子数，它就只能被一个固定原子所有。
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The ability of an atom to attract electrons, and in particular, in a covalent bond.
原子对电子的吸引能力，特别是在共价键中。
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So, essentially you've got a positive ball which is identical to the size of the atom.
首先你要有一个和原子差不多大小的,带正电荷的球。
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So, what this lets us do now is directly compare, for example, the strength of a bond in terms of a hydrogen atom and hydrogen molecule, compared to any kind of molecule that we want to graph on top of it.
因此，这让我们现在可以做到直接进行比较，比如，将一个氢原子，和一个氢分子的键的强度，与任何其它类型的分子进行比较,我们只需要把它的曲线也画在这幅图上。
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So, one difference between photoelectron spectroscopy and, for example, the photoelectric effect is that in this case, we're not just looking at one energy level, which is what we were looking at from the surface of a metal, now we're talking about this gaseous atom.
光电子能谱与光电效应的不同点在于，以这种情况为例，我们不只关心一个能级，就像原来在金属表面那样，现在我们研究的是气体原子，所以，我们可以从原子中。
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