TED-Ed
Jon Bergmann: Just how small is an atom?
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Just how small are atoms? Really, really, really small. This fast-paced animation from TED-Ed uses metaphors (imagine a blueberry the size of a football stadium!) to give a visceral sense of just how small atoms are. Lesson by Jon Bergmann, animation by Cognitive Media.
Jon Bergmann - Educator
Jon Bergmann co-wrote the book on the "flipped classroom" -- using video to help students master new ideas outside the traditional class setting. Full bio
Jon Bergmann co-wrote the book on the "flipped classroom" -- using video to help students master new ideas outside the traditional class setting. Full bio
Double-click the English transcript below to play the video.
（音乐）
你也许已经知道所有的东西
00:26
You probably already know
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00:28
everything is made up
of little tiny things called atoms
of little tiny things called atoms
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都是由微小的原子组成。
你可能还知道每一个原子是由更小的
00:30
or even that each atom
is made up of even smaller particles
is made up of even smaller particles
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叫做质子，中子和电子的微粒组成
00:33
called protons, neutrons and electrons.
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也许你听说过原子很小。
00:35
And you've probably heard
that atoms are small.
that atoms are small.
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我打赌，你从未想过它究竟有多小。
00:38
But I bet you haven't ever thought
about how small atoms really are.
about how small atoms really are.
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答案是，它们非常非常非常小。
00:42
Well, the answer is
that they are really, really small.
that they are really, really small.
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你提出问题了，到底原字有多小呢?
00:46
So you ask, just how small are atoms?
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为了去理解它，让我们先提出一个问题：
00:49
To understand this,
let's ask this question:
let's ask this question:
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一个柚子包含多少原子？
00:53
How many atoms are in a grapefruit?
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首先我们假设柚子完全由氮原子构成，
00:55
Well, let's assume that the grapefruit
is made up of only nitrogen atoms,
is made up of only nitrogen atoms,
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虽然不准确，但柚子中确实有氮原子。
00:59
which isn't at all true, but there
are nitrogen atoms in a grapefruit.
are nitrogen atoms in a grapefruit.
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为了便于观察，我们把原子放大到
01:02
To help you visualize this,
let's blow up each of the atoms
let's blow up each of the atoms
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一个蓝莓大小。
01:05
to the size of a blueberry.
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那总体柚子又会是多大呢？
01:07
And then how big
would the grapefruit have to be?
would the grapefruit have to be?
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它会跟地球的个头差不多。
01:10
It would have to be the same size of
-- well, actually, the Earth.
-- well, actually, the Earth.
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天啊！难道地球装满蓝莓的数量
01:14
That's crazy!
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01:16
You mean to say that if I filled
the Earth with blueberries,
the Earth with blueberries,
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会和柚子中的氮原子一样多？
01:18
I would have the same number
of nitrogen atoms as a grapefruit?
of nitrogen atoms as a grapefruit?
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的确如此！那么原子究竟有多小？
01:21
That's right!
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01:23
So how big is the atom?
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它小到
01:25
Well, it's really, really small!
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超出了你的
01:28
And you know what?
It gets even more crazy.
It gets even more crazy.
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想象。
01:31
Let's now look inside of each atom
-- and thus the blueberry, right? --
-- and thus the blueberry, right? --
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现在让我们看看原子内部，也就是蓝莓。
你会发现
01:34
What do you see there?
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原子有一个核心。
01:35
In the center of the atom
is something called the nucleus,
is something called the nucleus,
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其中包含着质子和中子，
01:38
which contains protons and neutrons,
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外围的是电子。
01:40
and on the outside, you'd see electrons.
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如果原子是地球中的蓝莓，
01:42
So how big is the nucleus?
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那么原子核又有多大呢？
01:44
If atoms are like blueberries
in the Earth,
in the Earth,
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01:46
how big would the nucleus be?
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你可能在物理书上看过原子的描绘，
01:48
You might remember the old pictures
of the atom from science class,
of the atom from science class,
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原子核是箭头所指的小点。
01:51
where you saw this tiny dot on the page
with an arrow pointing to the nucleus.
with an arrow pointing to the nucleus.
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这些图不是按比例画的，
01:55
Well, those pictures,
they're not drawn to scale,
they're not drawn to scale,
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所以并不准确。
01:57
so they're kind of wrong.
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那么真实的原子核多大呢？
01:59
So how big is the nucleus?
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如果你在蓝莓的内部
02:01
So if you popped open the blueberry
and were searching for the nucleus ...
and were searching for the nucleus ...
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搜索原子核，
结果是一无所获。
02:06
You know what? It would be invisible.
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因为我们看不到它！
02:08
It's too small to see!
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如果我们把原子，也就是蓝莓
02:10
OK. Let's blow up the atom --
the blueberry --
the blueberry --
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放大到房子的尺寸。
02:13
to the size of a house.
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02:15
So imagine a ball that is as tall
as a two-story house.
as a two-story house.
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想象下有两层房屋那么高。
我们在其中寻找原子核，
02:18
Let's look for the nucleus
in the center of the atom.
in the center of the atom.
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它就如一粒尘埃。
02:21
And do you know what?
It would just barely be visible.
It would just barely be visible.
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所以想要真正看清原子核，
02:25
So to get our minds wrapped
around how big the nucleus is,
around how big the nucleus is,
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还要把蓝莓放大到橄榄球场大小。
02:27
we need to blow up the blueberry,
up to the size of a football stadium.
up to the size of a football stadium.
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02:32
So imagine a ball the size
of a football stadium,
of a football stadium,
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想象一下，橄榄球场大小的原子。
02:35
and right smack dab
in the center of the atom,
in the center of the atom,
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在它的正中间，
02:38
you would find the nucleus,
and you could see it!
and you could see it!
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你终于找到了原子核！
而它只有玻璃弹子大小。
02:41
And it would be the size
of a small marble.
of a small marble.
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如果现在你都没有被震撼到，
02:45
And there's more, if I haven't
blown your mind by now.
blown your mind by now.
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那再来设想下原子中的质子，中子，电子。
02:47
Let's consider the atom some more.
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02:49
It contains protons,
neutrons and electrons.
neutrons and electrons.
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质子和中子组成了原子核，
02:51
The protons and neutrons
live inside of the nucleus,
live inside of the nucleus,
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几乎占了原子全部比重。
02:54
and contain almost
all of the mass of the atom.
all of the mass of the atom.
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在原子边缘的是电子。
02:56
Way on the edge are the electrons.
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02:58
So if an atom is like a ball
the size of a football stadium,
the size of a football stadium,
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一个橄榄球场大小的原子，
03:01
with the nucleus in the center,
and the electrons on the edge,
and the electrons on the edge,
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原子核在中心，而电子在边缘，
那么两者之间又是什么呢？
03:03
what is in between the nucleus
and the electrons?
and the electrons?
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虚空。
03:07
Surprisingly, the answer is empty space.
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（风声）
03:10
(Wind noise)
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没错，空无一物！
03:13
That's right. Empty!
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03:15
Between the nucleus and the electrons,
there are vast regions of empty space.
there are vast regions of empty space.
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在原子核和电子之间存在着大片空洞区域。
严格的说来还有电磁场，
03:19
Now, technically there are
some electromagnetic fields,
some electromagnetic fields,
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但从物质的角度看，还是空洞。
03:21
but in terms of stuff,
matter, it is empty.
matter, it is empty.
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而这空洞区域正是在
03:24
Remember this vast region of empty space
is inside the blueberry,
is inside the blueberry,
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蓝莓之中，而蓝莓又是在
03:28
which is inside the Earth,
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如地球大小的柚子之中。
03:30
which really are the atoms
in the grapefruit.
in the grapefruit.
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更奇异的是，
03:32
OK, one more thing,
if I can even get more bizarre.
if I can even get more bizarre.
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事实上原子的大部分质量集中在原子核，
03:36
Since virtually all the mass
of an atom is in the nucleus --
of an atom is in the nucleus --
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虽然电子也有一定质量，
03:40
now, there is some amount
of mass in the electrons,
of mass in the electrons,
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但是可以忽略。
03:43
but most of it is in the nucleus --
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那么原子核的密度是多少？
03:45
how dense is the nucleus?
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你会觉得不可思议。
03:46
Well, the answer is crazy.
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典型的原子的密度是
03:48
The density of a typical nucleus
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4乘以10的17次方千克/立方米。
03:50
is four times 10 to the 17th
kilograms per meter cubed.
kilograms per meter cubed.
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很难设想，那么换作英制单位是
03:54
But that's hard to visualize.
OK, I'll put it in English units.
OK, I'll put it in English units.
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2.5乘以10的16次方
03:57
2.5 times 10 to the 16th pounds
per cubic feet.
per cubic feet.
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磅/立方英尺。
如果还是很难想象，
04:02
OK, that's still kind of hard to figure.
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那么打个比方。
04:04
OK, here's what I want you to do.
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一个30厘米立方的盒子，
04:06
Make a box that is one foot
by one foot by one foot.
by one foot by one foot.
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一辆重两吨的汽车，
04:10
Now let's go and grab
all of the nuclei from a typical car.
all of the nuclei from a typical car.
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我们需要多少量汽车的原子核
04:14
Now, cars on average weigh two tons.
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装在一个盒子里
04:16
How many cars' nuclei would you
have to put into the box
have to put into the box
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才能达到一个原子核的密度？
04:20
to have your one-foot-box have
the same density of the nucleus?
the same density of the nucleus?
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一辆，两辆，还是一百辆？
04:23
Is it one car? Two?
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04:24
How about 100?
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都不是。
04:26
Nope, nope and nope.
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结果大得多。
04:28
The answer is much bigger.
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需要62亿辆。
04:30
It is 6.2 billion.
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这差不多是世界人口总数。
04:34
That is almost equal to the number
of people in the Earth.
of people in the Earth.
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所以如果每个人都拥有一辆车，
04:37
So if everyone in the Earth
owned their own car --
owned their own car --
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我们假象，
04:39
and they don't --
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04:40
(Cars honking)
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把这些车都装进盒子里，
04:42
and we put all of those
cars into your box ...
cars into your box ...
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就差不多相当于一个原子核的密度。
04:46
That would be about
the density of a nucleus.
the density of a nucleus.
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把世界上每一辆车都装进一30厘米立方的盒子中，
04:49
So I'm saying that if you took
every car in the world
every car in the world
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04:52
and put it into your one-foot box,
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你才得到原子核的密度。
04:54
you would have the density of one nucleus.
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我们回顾一下。
04:57
OK, let's review.
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原子极其渺小。
04:58
The atom is really,
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04:59
really, really small.
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柚子中的原子是地球中的蓝莓。
05:02
Think atoms in a grapefruit
like blueberries in the Earth.
like blueberries in the Earth.
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原子核更是出奇的小。
05:06
The nucleus is crazy small.
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把蓝莓放到大橄榄球场大小，
05:09
Now look inside the blueberry,
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05:10
and blow it up to the size
of a football stadium,
of a football stadium,
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原子核就是其中的玻璃弹子。
05:13
and now the nucleus
is a marble in the middle.
is a marble in the middle.
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原子内存在广阔的虚空。
05:16
The atom is made up
of vast regions of empty space.
of vast regions of empty space.
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很不寻常。
05:20
That's weird.
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原子核有极高的密度。
05:21
The nucleus has a crazy-high density.
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想想盒子里装的那些车。
05:23
Think of putting all those cars
in your one-foot box.
in your one-foot box.
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我洗洗睡了。
05:27
I think I'm tired.
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（打哈欠）
ABOUT THE SPEAKER
Jon Bergmann - EducatorJon Bergmann co-wrote the book on the "flipped classroom" -- using video to help students master new ideas outside the traditional class setting.
Why you should listen
Jon Bergmann is considered one of the pioneers in the Flipped Class Movement -- in fact, he co-wrote the book on the Flipped Classroom, available from ISTE Press in June 2012. Bergmann believes educators should ask one guiding question: What is best for my students in my classroom? To the best of his abilities he has done this in his two-plus decades as a high school science teacher. He received the Presidential Award for Excellence for Math and Science Teaching in 2002 and was named Semi-Finalist for Colorado Teacher of the Year in 2010. He blogs at flipped-learning.com.
He is the Lead Technology Facilitator for the Joseph Sears School in Kenilworth, Illinois.
Read about the making of "How Small Is an Atom?" >>
Jon Bergmann | Speaker | TED.com