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OK, today we're going to talk about the mole.
今天我们来谈一下摩尔。
Now, I know what you're thinking: "I know what a mole is, it's a small furry creature that digs holes in the ground and destroys gardens."
我知道你现在在想：“我知道摩尔是什么，它是毛茸茸的小生物，挖洞和破坏花园。”
And some of you might be thinking that it's a growth on your aunt's face with hairs sticking out of it.
有些人也许会认为它是阿姨脸上带有几根细毛的痣。
Well, in this case, a mole is a concept that we use in chemistry to count molecules, atoms, just about anything extremely small.
但今天所讲的摩尔，是化学中的一个概念，用来计算分子、或是任何极小物质的数量。
Have you ever wondered how many atoms there are in the universe? Or in your body? Or even in a grain of sand?
你曾经想过这个宇宙，或是你的身体、或是一粒沙子里到底有多少原子吗？
Scientists have wanted to answer that question, but how do you count something as small as an atom?
科学家想解决这个问题，但是你要如何计算小到像原子一样的东西？
Well, in 1811, someone had an idea that if you had equal volumes of gases, at the same temperature and pressure, they would contain an equal number of particles.
在1811年，有个人突发奇想，认为如果气体体积相同，在同等温度及压力下，它们应该会有相同的分子数量。
His name was Lorenzo Romano Amedeo Carlo Avogadro.
这个人的名字是阿莫迪欧阿伏加德罗。
I wonder how long it took him to sign autographs.
我很好奇他签个名要花多长时间。
Unfortunately for Avogadro, most scientists didn't accept the idea of the atom, and there was no way to prove he was right.
不幸的是，大部分科学家不接受这个想法，而他也没有方法可以证明他是对的。
There was no clear difference between atoms and molecules.
原子和分子之间并没有明显的差异。
Most scientists looked at Avogadro's work as purely hypothetical, and didn't give it much thought.
大多数科学家认为阿伏加德罗的理论纯粹是个假说，并没有特别去思考这件事。
But it turned out he was right! By late 1860, Avogadro was proven correct, and his work helped lay the foundation for the atomic theory. Unfortunately, Avogadro died in 1856.
但事实证明他是对的！1860年底，阿伏加德罗的想法被证明是对的，而且他的努力奠定了原子理论的基石。不幸的是，阿伏加德罗死于1856年。
Now the thing is that the amount of particles in even small samples is tremendous.
现在的问题是，即使是小东西，它上面的分子总数也是非常巨大的。
For example, if you have a balloon of any gas at zero degrees Celcius, and at a pressure of one atmosphere, then you have precisely six hundred and two sextillion gas particles.
比如，假使你有一个装有任何气体的汽球，在零摄氏度和一大气压的条件下，那你会有602乘10的21次方个气体分子。
That is, you have six with 23 zeros after it particles of gas in the container.
就是6后面带有23个0，这么多个分子在里面。
Or in scientific notation, 6.02 times10 to the 23rd particles.
或用科学记号表示为6.02×10的23次方个分子。
This example is a little misleading, because gases take up a lot of space due to the high kinetic energy of the gas particles, and it leaves you thinking atoms are bigger than they really are.
这个例子有点儿误导人，因为高动能的气体分子会占用较大的空间，这让你感觉原子比原来的大。
Instead, think of water molecules.
相对地，我们看一下水分子。
If you pour 18.01grams of water into a glass, which is 18.01 milliliters, which is like three and a half teaspoons of water, you'll have 602 sextillion molecules of water.
如果你倒18.01克的水到杯子里，就是18.01毫升，大约是三个半茶匙的水，你就有602乘以10的21次方个水分子。
Since Lorenzo Romano, uh, never mind, Avogadro was the first one to come up with this idea, scientists named the number 6.02 times 10 to the 23rd after him.
自从洛伦佐·罗马诺...嗯，算了。阿伏加德罗是第一位提出这个想法的人，科学家用他的名字来命名6.02乘以10的23次方这个数字。
It is simply known as Avogadros's number.
这就是熟知的阿伏加德罗常数。
