重水之所以重是因为水中氢的重量是普通氢的两倍（它的原子核中有一个质子和一个中子，而不仅仅是一个质子）。

Heavy water is heavy because the hydrogen in it weighs twice as much as ordinary hydrogen (it has a proton and a neutron in its nucleus, instead of just a proton).

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从该液体中最先逸出的气泡是空气和氢的混合物。

The first bubbles to escape from the liquid are a mixture of air and hydrogen.

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此外，氢的来源也是个问题。

And there is the problem of where to get the hydrogen.

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HBr So for example, if I want to look at HBr there's a simple case, right, hydrogen bromine.

如果我想研究,这是个简单的例子，溴化氢。

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If we take hydrogen peroxide in the liquid state, it can break down to form water and oxygen.

如果我们有一些液态的过氧化氢，它会分解成水和氧气。

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It is a double column, You can see, it starts with hydrogen and goes to mercury in ascending order of atomic mass.

双纵栏，你们看到，从氢开始,然后到水银，按原子质量的升序排列。

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