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He says the methane discovery presents scientists with a mystery because it is still not clear how the gas is being produced.
VOA: special.2009.12.30
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So, what will start with on Monday is doing the most simple example of methane using these Lewis structure rules.
因此，下周一上课,我们会先以最简单的例子--甲烷开始,使用这些路易斯结构的规则。
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Methane, there are certainly some solid bonds there, but breaking those to form CO2 and water, well it's worth it, right, energetically.
酒精中的确含有很强的化学键，但是打断这些化学键然后生成二氧化碳和水，从能量上来看是值得的。
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Currently,the best explanation for the loss of methane is that it chemically reacts with dust in the atmosphere.
VOA: special.2009.12.30
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It's 109 . 5 is what we would expect for methane because it's tetravalent, but here we're just seeing something that's divalent, and they're both in p orbitals that are perpendicular to each other.
因为甲烷是四价的，我们预测是109。,但这里我们，看到的是二价的，它们都在。
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In January,a team of NASA and university scientists announced that they had found methane gas on Mars.
VOA: special.2009.12.30
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Burn coal to make it, catalytic decomposition of methane, you get the hydrogen, where does the carbon go?
通过烧煤得到，催化分解甲烷，可以得到氢，碳去哪儿了？
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But Michael Meyer notes that methane also can come from a purely non-biological process called serpentinization.
VOA: special.2009.12.30
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You burn methane, and it combines with oxygen to form water, to form CO2.
燃烧酒精，酒精分子和氧气结合形成水和二氧化碳。
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The gas is mainly methane. It produces half the carbon dioxide of other fossil fuels.
VOA: special.2009.10.23
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So, just to go through a basic example, let's just look at the burning of methane.
那么我们来推导一些，基本的例子，让我们。
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This suggests processes that both supply and remove methane from the atmosphere in certain places.
VOA: special.2009.12.30
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As we see a little bit later, I could talk about the carbon-hydrogen bond in methane where there is a plurality of bonds. In this case, there is only the one bond but I just want to get the formulas.
因为我们后来看到一点点，我能讨论甲烷中的碳氢共价键,那有许多共价键，这种情况下，这只有一条共价键,但我想得到氟。
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We also talk to a NASA expert about the discovery of methane gas on Mars.
VOA: special.2009.12.30
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So this should immediately look like a problem because we know, in fact, that methane is tetravalent, and this is telling us it's only divalent.
显然这看起来是一个问题,因为我们知道实际上，甲烷是四价的，而这告诉我们它仅仅是二价的。
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The orbiter could finally provide evidence about how methane on Mars is created and destroyed.
VOA: special.2009.12.30
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Here is the question. Is methane a polar molecule or a nonpolar molecule? Let's look carefully.
问题是，甲烷是一个极性分子还是非极性分子,我们仔细看看。
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Martian methane is also unusual because it is not evenly spread over the planet.
VOA: special.2009.12.30
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So, using our simple valence bond theory, what we would expect is that we want to pair up any unpaired electrons in methane with unpaired electrons from hydrogen and form bonds.
利用简单的价电子成键理论，我们预计,要把所有甲烷中没有配对的电子,和氢原子中没有配对的电子配对来形成键。
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For example,animal waste and cattle digestive systems release methane gas.
VOA: special.2010.01.05
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Let's try something like four, which is what? Methane.
试试配位原子有4个的，那是什么东西，甲烷。
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On Earth,biological activity is very effective in making methane.
VOA: special.2009.12.30
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All right, so let's consider our methane situation now that we have our hybrid orbitals.
好，让我们考虑甲烷的情形,既然我们有了杂化轨道。
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Methane is better known as natural gas.
VOA: special.2009.12.30
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Let's go back to methane and see what happens there.
让我们回到甲烷，看看发生了什么。
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He calls it "cow power to horsepower." Leonhardt says the challenge is to cost-effectively remove impurities from the manure-derived methane.
VOA: standard.2010.02.23
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We were talking about methane, which has only one central atom.
我们讨论的甲烷，只有一个中心原子。
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Manure from about 1,000 cows goes in one end and then, controlled decomposition yields methane gas at the other.
VOA: standard.2010.02.23
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So let's think about methane using valence bond theory.
让我们用价电子成键理论来看一看甲烷。
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Methane we can draw. It looks like this.
我们可以画出甲烷，就是这样子。
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