Just How Small is an Atom?
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0:00 - 0:13(Music)
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0:13 - 0:15You probably already know that everything is made up of
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0:15 - 0:17little tiny things called atoms.
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0:17 - 0:20You might even know that each atom is made up of even smaller particles
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0:20 - 0:22called protons, neutrons and electrons.
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0:22 - 0:25And you've probably heard that atoms are small.
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0:25 - 0:28But I bet you haven't ever thought about how small atoms really are.
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0:28 - 0:33Well, the answer is that they are really, really, really small.
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0:33 - 0:36So you ask, just how small are atoms?
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0:36 - 0:39To understand this, let's ask this question:
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0:39 - 0:42How many atoms are in a grapefruit?
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0:42 - 0:45Well let's assume that the grapefruit is made up of only nitrogen atoms,
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0:45 - 0:49which isn't at all true, but there are nitrogen atoms in a grapefruit.
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0:49 - 0:52Well, to help you visualize this, let's blow up each of the atoms
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0:52 - 0:54to the size of a blueberry.
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0:54 - 0:57And then how big would the grapefruit have to be?
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0:57 - 1:01It would have to be the same size of -- well, actually, the Earth.
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1:01 - 1:05That's crazy! You mean to say that if I filled the Earth with blueberries,
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1:05 - 1:08I would have the same number of nitrogen atoms as a grapefruit?
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1:08 - 1:11That's right! So how big is the atom?
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1:11 - 1:14Well, it's really, really, really, really small.
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1:14 - 1:16And you know what?
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1:16 - 1:18It gets even more crazy.
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1:18 - 1:21Let's now look inside of each atom -- and thus the blueberry, right? --
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1:21 - 1:22What do you see there?
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1:22 - 1:25In the center of the atom is something called the nucleus,
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1:25 - 1:27which contains protons and neutrons,
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1:27 - 1:29and on the outside you'd see electrons.
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1:29 - 1:31So how big is the nucleus?
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1:31 - 1:34Well, if atoms are like blueberries in the Earth, how big would the nucleus be?
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1:34 - 1:37You might remember the old pictures of the atom from your science class,
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1:37 - 1:41where you saw this tiny dot on the page with an arrow pointing to the nucleus.
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1:41 - 1:44Well, those pictures, they're not drawn to scale,
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1:44 - 1:45so they're kind of wrong.
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1:45 - 1:47So how big is the nucleus?
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1:47 - 1:50So if you popped open the blueberry
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1:50 - 1:52and were searching for the nucleus,
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1:52 - 1:55you know what? It would be invisible.
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1:55 - 1:57It's too small to see!
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1:57 - 2:00OK. Let's blow up the atom -- the blueberry --
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2:00 - 2:02to the size of a house.
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2:02 - 2:05So imagine a ball that is as tall as a two-story house.
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2:05 - 2:08Let's look for the nucleus in the center of the atom.
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2:08 - 2:11And do you know what? It would just barely be visible.
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2:11 - 2:14So to get our minds wrapped around how big the nucleus is,
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2:14 - 2:19we need to blow up the blueberry, up to the size of a football stadium.
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2:19 - 2:22So imagine a ball the size of a football stadium,
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2:22 - 2:25and right smack dab in the center of the atom,
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2:25 - 2:27you would find the nucleus, and you could see it!
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2:27 - 2:31And it would be the size of a small marble.
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2:31 - 2:34And there's more, if I haven't blown your mind by now.
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2:34 - 2:38Let's consider the atom some more. It contains protons, neutrons and electrons.
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2:38 - 2:40The protons and neutrons live inside of the nucleus,
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2:40 - 2:42and contain almost all of the mass of the atom.
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2:42 - 2:45Way on the edge are the electrons.
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2:45 - 2:48So if an atom is like a ball the size of a football stadium,
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2:48 - 2:50with the nucleus in the center, and the electrons on the edge,
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2:50 - 2:53what is in between the nucleus and the electrons?
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2:53 - 2:56Surprisingly, the answer is empty space.
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2:56 - 2:59(Wind noise)
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2:59 - 3:02That's right. Empty!
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3:02 - 3:05Between the nucleus and the electrons, there are vast regions of empty space.
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3:05 - 3:08Now, technically there are some electromagnetic fields,
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3:08 - 3:11but in terms of stuff, matter, it is empty.
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3:11 - 3:14Remember this vast region of empty space
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3:14 - 3:16is inside the blueberry, which is inside the Earth,
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3:16 - 3:19which really are the atoms in the grapefruit.
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3:19 - 3:23OK, one more thing, if I can even get more bizarre.
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3:23 - 3:26Since virtually all the mass of an atom is in the nucleus --
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3:26 - 3:29now, there is some amount of mass in the electrons,
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3:29 - 3:31but most of it is in the nucleus --
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3:31 - 3:33how dense is the nucleus?
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3:33 - 3:35Well, the answer is crazy.
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3:35 - 3:37The density of a typical nucleus
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3:37 - 3:41is four times 10 to the 17th kilograms per meter cubed.
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3:41 - 3:44But that's hard to visualize. OK, I'll put it in English units.
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3:44 - 3:472.5 times 10 to the 16th
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3:47 - 3:49pounds per cubic feet.
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3:49 - 3:51OK, that's still kind of hard to figure.
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3:51 - 3:53OK, here's what I want you to do.
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3:53 - 3:56Make a box that is one foot by one foot by one foot.
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3:56 - 4:00Now let's go and grab all of the nuclei from a typical car.
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4:00 - 4:03Now, cars on average weigh two tons.
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4:03 - 4:06How many cars' nuclei would you have to put into the box
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4:06 - 4:09to have your one-foot-box have the same density of the nucleus?
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4:09 - 4:12Is it one car? Two? How about 100?
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4:12 - 4:15Nope, nope and nope.
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4:15 - 4:17The answer is much bigger.
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4:17 - 4:20It is 6.2 billion.
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4:20 - 4:23That is almost equal to the number of people in the Earth.
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4:23 - 4:26So if everyone in the Earth owned their own car --
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4:26 - 4:28and they don't --
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4:28 - 4:31and we put all of those cars into your box,
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4:31 - 4:35that would be about the density of a nucleus.
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4:35 - 4:40So I'm saying that if you took every car in the world and put it into your one-foot box,
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4:40 - 4:43you would have the density of one nucleus.
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4:43 - 4:45OK, let's review.
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4:45 - 4:48The atom is really, really, really small.
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4:48 - 4:52Think atoms in a grapefruit like blueberries in the Earth.
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4:52 - 4:55The nucleus is crazy small.
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4:55 - 4:59Now look inside the blueberry, and blow it up to the size of a football stadium,
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4:59 - 5:02and now the nucleus is a marble in the middle.
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5:02 - 5:06The atom is made up of vast regions of empty space.
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5:06 - 5:08That's weird.
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5:08 - 5:10The nucleus has a crazy-high density.
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5:10 - 5:13Think of putting all those cars in your one-foot box.
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5:13 - 5:16I think I'm tired.
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5:16 - 5:19(Yawning)
- Title:
- Just How Small is an Atom?
- Speaker:
- Jon Bergmann
- Description:
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Just how small are atoms? And what's inside them? The answers turn out to be astounding, even for those who think they know. This fast-paced animation uses spectacular metaphors (imagine a blueberry the size of a football stadium!) to give a visceral sense of the building blocks that make our world.
Lesson by Jonathan Bergmann, animation by Cognitive Media.
- Video Language:
- English
- Team:
closed TED
- Project:
- TED-Ed
- Duration:
- 05:28
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Krystian Aparta edited English subtitles for Just How Small is an Atom? | |
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Krystian Aparta commented on English subtitles for Just How Small is an Atom? | |
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Krystian Aparta edited English subtitles for Just How Small is an Atom? | |
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Mahmoud Aghiorly added a translation |
Krystian Aparta
The English transcript was updated on 2/13/2015.