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元素周期表之神奇的氦元素 – 译学馆
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元素周期表之神奇的氦元素

Helium (some extra stuff) - Periodic Table of Videos

现在最为人所熟知的稀有气体氦……
Now, of course, the most famous thing about helium…
这么说吧 众所周知的氦的最新功能是
Or at least the thing that most people know,
如果你吸入氦 会让你的声音变化
is if you breathe in helium, it makes your voice change.
让它变得尖锐
Makes it go squeaky.
我从未尝试过……所以
I’ve never tried this… So,
我觉着在Neil和Brady的帮助下
I decided that it’d be rather fun to try this time
这次尝试会很有意思
with Neil and Brady helping me.
Brady:你紧张吗?
[Brady ] Are you nervous then? Erm.
呃 不 我还不紧张
No, I’m not nervous yet. Well,
呃 现在紧张了
I am nervous,
我刚刚在维基百科上看到有人吸氦吸死了
I’ve just read on Wikipedia that somebody died after breathing helium.
但我不希望这在我身上发生
But I hope it won’t happen now.
毕其功于一役
Make a good video if it does.
[吸氦气中]
*takes a breath of helium from balloon*
[高音]你好 我正含着氦气说话
*higher pitched* Hello, I’m now talking with helium in my voice.
效果很快就消失了
And it quickly goes away.
这是我第一次尝试
And the first time I did it,
我吸得不够多所以声音变化不大
I didn’t breathe deeply enough so my voice didn’t change very much.
但第二次 它确实有明显的变化
But the second time, it did change really quite significantly.
[吸了第二口氦气]
*takes second breath of helium from balloon*
[更高音调]有超过115个视频能观看
*an even higher pitch* There are a hundred and fifteen more videos to watch.
哦 事实上是117个
In fact, there are a hundred and seventeen more videos to watch.
这有区别吗
Was that different?
当你这么做以后
When you’re doing it, it just
感觉就像你正常说话
feels as if you’re talking normally,
但声调就是不一样了
but somehow your voice comes out differently.
我想它就像你因为
I suppose it’s like when you have
重感冒之类的
a very bad cold or something like that that,
改变了你的声音
your voice changes as well.
我不认为这是个你能
I don’t think that this is a good experiment
自己尝试的实验
for you to try yourselves.
当然我不认为你吸一次就有危险
I don’t think it’s dangerous if you do it just once.
但如果持续吸入 后果可能很严重
But if you keep on breathing helium, it can be really quite dangerous.
实际上我真看到有人吸过多氦气
And in fact, I read recently about somebody who died
而死亡
after breathing too much.
但你仅做尝试地吸 还是很安全的
But if you breathe helium under controlled conditions, it’s quite safe.
还有 它被用于深海潜水者身上
And in fact, it’s used for deep-sea divers.
这个例子是 你处于深海时……
One of the problems if you’re diving very deep under the sea…
要呼吸高压气体
Is that, you have to breathe air that’s under pressure;
不然你就没法呼吸了
otherwise you can’t open and shut your lungs.
在高压下 空气里的氮气溶解于血液中
Under pressure, the nitrogen in the air dissolves in your blood. Now,
潜在海中时这问题可能无关紧要
this doesn’t matter when you’re down at the bottom.
但你上浮时 浮得太快
But as you come up, if you surface too quickly,
会导致氮气泡从血液中溢出
the nitrogen can come out as bubbles in your blood.
同时导致非常严重的后果……
And cause a very painful condition…
这种现象 潜水员把这叫”减压病”
Which for some reason, the divers called the”bends”.
科学研究表明如果你把
And it’s been found that if you replace
潜水员氧气瓶里
the nitrogen in the divers breathing air, or
绝大多数的氮气换成氦气……
at least most of the nitrogen with helium…
他们就不会得”减压病”了
Then they don’t suffer from”bends”.
[美联社档案画外音]“在150英尺下 体表压力骤增
[AP Archive voice over]”Below 150 feet, the pressure on the body rises dramatically
潜水员必须呼吸氦氧混合气”
and divers must operate on a mixture of helium and oxygen.”
但这样 他们的声调肯定会变高……
But of course their voices go squeaky…
所以在潜水员无线电另一边的人
So the people on the other end of the telephone,
都需要在
talking to the divers, need to
无线电上装滤波器……
have some sort of electronic filter…
滤波器能使他们的声音还原
So that the divers’ voices are transposed
所以他们就能听懂潜水员讲什么了
and they can still understand what they’re saying.
氦气下音调改变的原因可能有多方面
The reason why your voice changes is probably due to a number of factors.
其中一个可能是声音在氦气中的速度高于
One of the factors is that the speed of sound is much greater
它在空气中的速度
in helium than it is in air.
还有可能是声速与
The reason for this, is that the speed of
它要通过的气体的密度
sound is related to the mass of the molecules in
有一定程度上的关系
the gas that the sound is going through.
还有氦气分子在空气中比氮气和氧气
And the helium molecule is much lighter than nitrogen or oxygen,
轻多了
which you find in air.
当然你可以试试氢气
Of course if you breathed hydrogen, it
声速应该会更快
would be even faster the speed of sound,
但你可能会自爆
but you then blow yourself up.
所以这不是任何人都能尝试的
So this is not something that anybody should try.
另外 人类的大脑结构中
The other point, is that inside the Human head,
事实上 所有动物的大脑中
in fact, the head of all animals,
有很多结构让震动变得很复杂
there are complicated resonances caused by the different spaces.
你感冒的时候 声音变化就是因为
And that’s why your voice changes when you have a cold,
一些导管堵塞
because some of the tubes are blocked. So,
我有个想法…
I had the idea…
也许你把放着歌的iPhone
that perhaps, if you put an iPhone playing music
放进氦气 声音也会变化
in helium, that the sound might change.
尽管其中不存在太多共振
Though there isn’t much to resonate in an iPhone.
[iPhone中传来音乐]
*music from iPhone*
但Neil和Brady很想试试
But Neil and Brady were quite keen to try.
来看看我们的第一个用塑料袋做的实验
And our first experiments
有点失败
with a small plastic bag were a bit of a failure.
所以Neil拿了个大塑料袋并装满氦气
So then Neil got a really big plastic bag and filled it with helium.
你把袋子套上iPhone时
And when you put it over the iPhone.
令人惊讶的是
Most surprisingly,
声调没有变化 但声音变小了
the notes didn’t change, but the sound was attenuated much more.
[音乐持续中]
*music continues*
它的声音更小了
So it sounded much quieter.
[音乐持续中]
*music continues*
我不知道这是为什么
I’m not sure why this is,
但结果令人惊奇
but it was quite a striking effect.
随着Neil把袋子套上摘下
And Neil put the bag on and off.
[音乐持续中]
*music continues*
你可以听到袋子摘掉时
And you could hear the music getting louder
声音变大 套上时
when the bag was not there and going
变小
quieter again when he put it back.
[音乐持续中]
*music continues*
我们用一个袋子装空气
And we did a control experiment with a
用它作对照实验
bag of air, and it wasn’t
与充满氦气的袋子不同
the bag it definitely was the helium.
但我最喜欢的是Neil
But the thing I liked best was that Neil
放开了袋子然后
then let go of the bag, and it
它飘起来直到停在房顶上
went up to the ceiling and stayed there.
尽管袋子底部打开着
Even though the bottom of the bag was completely open.
但氦气还是保留在翻转的袋子中
So once the helium is trapped in an upturned plastic bag,
它会在那停留很久
it will sit there for quite a long time.
[音乐持续中]
*music continues*
因为氦气是惰性气体……
Because helium is an inert gas…
因为他有一对成对电子……
Because it has two electrons that are paired…
它与常见化合物不同
It doesn’t form conventional chemical compounds in the way
比如说氢和钠
that say hydrogen does or sodium.
但几个月前
But there’s a very recent
有报告说
paper published just a few months ago,
这报告写着“惰性气体化合:氦遇上钠”
in this journal here, where you can see it says”Noble gas compounds: when helium met sodium”.
这些人设计了一个特别的实验
And the people here have done a really extraordinary experiment,
他们把金属钠和氦气混进金刚石压砧里
where they mixed sodium metal in helium gas in a diamond anvil cell.
我们有一个介绍它的运转方式的视频
We have a video that explains how these work.
通过这些压腔 可以得到很高的压力
But in these cells, you can get really high pressures.
在这种情况下它能达到
In their case, they went up to a pressure
近三百万个大气压
of nearly three million atmospheres.
正常气压的三百万倍
Three million times higher than atmospheric pressure.
他们成功地做到了 然后金属钠……
And when they did this they found, remarkably, that sodium metal…
就和氦气结合了
forms a compound with helium.
但氦还是中性分子 没有氦正或负离子
Where there is helium which is still chemically neutral: not helium plus or helium minus.
钠在晶胞中就在两个氦原子间 两个电子
And sodium and in the lattice between them, there are two electrons,
处于它们之间 现在讲金属钠
which are sitting there. Now normally in sodium metal,
它是一种金属 里面的电子是
because it’s a metal, the electrons are,
容易失去的 从而使结构稳定
if you like smeared out, de-localized through the structure,
这个是因为钠的金属性
that’s what gives it its metallic properties.
但在这个晶胞内:Na2He
But in this salt: Na2He.
两个钠原子与一个氦原子结合
Two sodium atoms for each helium atom,
我们可以预测
the electrons are localized and they predicted,
但观察不了里面的电子的位置
but they weren’t able to observe…
钠氦化合物在高压下的结构应该会更清晰
That actually under these high pressures the sodium and helium mixture should become transparent.
确实有意思
So it’s really quite exciting.
因为当化学老师告诉你氦气没有化合物
So if your teachers tell you that helium doesn’t form compounds.
这种说法既对也错
They’re both right and wrong.
对是因为它无法在常压下形成
They’re right, because it doesn’t form compounds under
化合物 错是因为在三百万个大气压下
normal conditions, but they’re wrong because at three million atmospheres,
可以形成
Yes, you can get some.
之所以氦在太阳内
The reason why there is helium in the Sun.
存在 是因为太阳里发生的核反应
Is partly because the nuclear reactions that take place in the Sun…
创造了氦原子
are responsible for creating helium.
氢原子在极限高压高温时
Hydrogen atoms, under these enormously high pressures and temperature,
会聚合在一起
the hydrogen atoms can fuse together,
这过程称为核聚变 最终产生氦原子
by a process called fusion, to generate helium.
我们在正常情况下
Now and the normal circumstances,
没有办法在地球上发生这样的反应
it’s not possible to do this on Earth.
但假如你有一个核弹
But if you take a nuclear bomb,
你可以用核弹触发这次聚变
you can use an atom bomb to trigger the fusion of,
通常用氘或氚等……
usually deuterium or tritium…
这些是氢的同位素 他们能够
these are isotopes of hydrogen and they can
通过聚合生成氦
be made to fuse to create helium.
[美联社档案画外音]”漂在比基尼泻湖不显眼的驳船上
[Archive voice over]”On this rather unimpressive barge, floating in the Bikini Lagoon,
栖息着承载着希望的设备
rests the device which carried the hopes
也代表了武器发展过程中的一大进步”
for a large step forward in the weapons development program.”
[低沉的核爆炸声]
*muffled sound of a nuclear explosion*
“航拍器隔着50英里 照片规格14×18英里
“The distance of the camera aircraft is 50 miles. The frame size of the picture is 14 by 18 miles,
视频以正常速度播放”
the film is running at normal speed.”
我们仍然有望通过拖卡马克装置控制反应
There is also hope that you can do controlled fusion in reactors called Tokamaks.
在最后也有可能通过聚合
Where eventually, it may be possible to use the fusion
氢来制造氦原子……
of hydrogen atoms to make helium…
产生一种清洁电能 然而
as a way of generating very clean electricity. However,
通过我近一生的实验
experiments have been going on for most of my lifetime,
尽管结果是有希望的
and although the results are promising,
但它们远远无法达到商业化发电的效果
they’re nowhere near being commercial production of electricity.
最常见氦原子同位素是氦-4:含有两个质子两个中子
The most common isotope of helium is helium-4: with two protons and two neutrons.
还有种稀有同位素 氦-3
There is a very rare isotope, helium-3,
含有两个质子一个中子
which has two protons and one neutron.
液态氦-3的性质明显不同于
And the properties of liquid helium-3 are significantly different
液态氦-4的性质
from the properties of liquid helium-4.
因为这些液体在低温下
Because at the very low temperatures of these liquids,
量子效应产生的效果非常明显
the quantum effects become very important.
事实上 我刚读到
In fact, I’ve read,
我不知道是不是真的 氦-3和氦-4
and I don’t know if it’s true, that liquid helium-3 and liquid helium-4
是不互溶的 这不奇怪吗?
are immiscible, they don’t mix together, which is really quite weird?
氦-3具有超流体性
Helium-3 can also behave as are superfluid,
这意味着它能爬上盛它的容器 相反
which means that it can creep upwards out of its container. Whereas,
在正常情况下 我们把一种液体
normally, if we put a liquid, say
比如说茶倒入茶杯不会流出来 但想象着
tea into my cup, it stays there, but imagine
如果它爬上杯壁然后流出来
if it crept up the sides and went out.
氦着实是一种令人兴奋的元素
So helium is a really very exciting element.
Brady:好了 还是让我们播放音乐吧
[Brady] Alright, let me start the music…

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视频概述

氦元素作为稀有气体以其稳定的性质而总被人们抛弃对于它的研究,如今,对于氦气性质与应用的探究,值得为我们所了解。

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视频来源

https://www.youtube.com/watch?v=ak_kvs4iQpk

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