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.
00:26
You probably already know
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everything is made up
of little tiny things called atoms
of little tiny things called atoms
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or even that each atom
is made up of even smaller particles
is made up of even smaller particles
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called protons, neutrons and electrons.
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And you've probably heard
that atoms are small.
that atoms are small.
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But I bet you haven't ever thought
about how small atoms really are.
about how small atoms really are.
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Well, the answer is
that they are really, really small.
that they are really, really small.
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So you ask, just how small are atoms?
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To understand this,
let's ask this question:
let's ask this question:
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How many atoms are in a grapefruit?
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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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which isn't at all true, but there
are nitrogen atoms in a grapefruit.
are nitrogen atoms in a grapefruit.
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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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to the size of a blueberry.
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And then how big
would the grapefruit have to be?
would the grapefruit have to be?
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It would have to be the same size of
-- well, actually, the Earth.
-- well, actually, the Earth.
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That's crazy!
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You mean to say that if I filled
the Earth with blueberries,
the Earth with blueberries,
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I would have the same number
of nitrogen atoms as a grapefruit?
of nitrogen atoms as a grapefruit?
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01:21
That's right!
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So how big is the atom?
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Well, it's really, really small!
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And you know what?
It gets even more crazy.
It gets even more crazy.
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Let's now look inside of each atom
-- and thus the blueberry, right? --
-- and thus the blueberry, right? --
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What do you see there?
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In the center of the atom
is something called the nucleus,
is something called the nucleus,
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which contains protons and neutrons,
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and on the outside, you'd see electrons.
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So how big is the nucleus?
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If atoms are like blueberries
in the Earth,
in the Earth,
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how big would the nucleus be?
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You might remember the old pictures
of the atom from science class,
of the atom from science class,
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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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Well, those pictures,
they're not drawn to scale,
they're not drawn to scale,
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so they're kind of wrong.
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So how big is the nucleus?
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So if you popped open the blueberry
and were searching for the nucleus ...
and were searching for the nucleus ...
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You know what? It would be invisible.
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It's too small to see!
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02:10
OK. Let's blow up the atom --
the blueberry --
the blueberry --
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to the size of a house.
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So imagine a ball that is as tall
as a two-story house.
as a two-story house.
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Let's look for the nucleus
in the center of the atom.
in the center of the atom.
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And do you know what?
It would just barely be visible.
It would just barely be visible.
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So to get our minds wrapped
around how big the nucleus is,
around how big the nucleus is,
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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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So imagine a ball the size
of a football stadium,
of a football stadium,
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and right smack dab
in the center of the atom,
in the center of the atom,
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you would find the nucleus,
and you could see it!
and you could see it!
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02:41
And it would be the size
of a small marble.
of a small marble.
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02:45
And there's more, if I haven't
blown your mind by now.
blown your mind by now.
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Let's consider the atom some more.
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It contains protons,
neutrons and electrons.
neutrons and electrons.
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The protons and neutrons
live inside of the nucleus,
live inside of the nucleus,
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and contain almost
all of the mass of the atom.
all of the mass of the atom.
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Way on the edge are the electrons.
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So if an atom is like a ball
the size of a football stadium,
the size of a football stadium,
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with the nucleus in the center,
and the electrons on the edge,
and the electrons on the edge,
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what is in between the nucleus
and the electrons?
and the electrons?
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Surprisingly, the answer is empty space.
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(Wind noise)
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That's right. Empty!
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Between the nucleus and the electrons,
there are vast regions of empty space.
there are vast regions of empty space.
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Now, technically there are
some electromagnetic fields,
some electromagnetic fields,
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but in terms of stuff,
matter, it is empty.
matter, it is empty.
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Remember this vast region of empty space
is inside the blueberry,
is inside the blueberry,
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which is inside the Earth,
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which really are the atoms
in the grapefruit.
in the grapefruit.
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03:32
OK, one more thing,
if I can even get more bizarre.
if I can even get more bizarre.
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Since virtually all the mass
of an atom is in the nucleus --
of an atom is in the nucleus --
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now, there is some amount
of mass in the electrons,
of mass in the electrons,
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but most of it is in the nucleus --
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how dense is the nucleus?
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Well, the answer is crazy.
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The density of a typical nucleus
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is four times 10 to the 17th
kilograms per meter cubed.
kilograms per meter cubed.
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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 times 10 to the 16th pounds
per cubic feet.
per cubic feet.
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04:02
OK, that's still kind of hard to figure.
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04:04
OK, here's what I want you to do.
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Make a box that is one foot
by one foot by one foot.
by one foot by one foot.
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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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Now, cars on average weigh two tons.
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How many cars' nuclei would you
have to put into the box
have to put into the box
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to have your one-foot-box have
the same density of the nucleus?
the same density of the nucleus?
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Is it one car? Two?
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How about 100?
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Nope, nope and nope.
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The answer is much bigger.
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It is 6.2 billion.
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That is almost equal to the number
of people in the Earth.
of people in the Earth.
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So if everyone in the Earth
owned their own car --
owned their own car --
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and they don't --
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(Cars honking)
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and we put all of those
cars into your box ...
cars into your box ...
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That would be about
the density of a nucleus.
the density of a nucleus.
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So I'm saying that if you took
every car in the world
every car in the world
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and put it into your one-foot box,
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you would have the density of one nucleus.
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OK, let's review.
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The atom is really,
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really, really small.
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Think atoms in a grapefruit
like blueberries in the Earth.
like blueberries in the Earth.
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The nucleus is crazy small.
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Now look inside the blueberry,
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and blow it up to the size
of a football stadium,
of a football stadium,
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and now the nucleus
is a marble in the middle.
is a marble in the middle.
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The atom is made up
of vast regions of empty space.
of vast regions of empty space.
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That's weird.
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The nucleus has a crazy-high density.
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Think of putting all those cars
in your one-foot box.
in your one-foot box.
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I think I'm tired.
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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