Welcome back, fellow scientists! Justin here. Are you ready to dive back into some matter?
I was. Literally. Uh, see, yesterday I wanted to go for a swim in my favorite pond, but when I got
there, it was completely frozen. And that got me thinking; why can't we go swimming in a frozen
pond? No, I'm serious. Think about it. Ice and water are all made up of the same stuff, right? So
why is it easy to move through water, but ice is all hard and tough? Well, to answer that question,
we're going to need to learn more about the states of matter. By the end of today's lesson, you will
be able to identify the four states of matter and describe their properties. Let's get into it.
In our last lesson, we learned that matter is anything that has mass and volume. This
means that wildly different things can all be matter, from an aardvark to pineapple
juice to the hydrogen and helium gases that form the stars of our universe.
So, as you can see, matter comes in all sorts of shapes and sizes - and states.
What is a state? Well, state is one of those words with more than one definition,
but in this case, it means the form that matter is in. Matter comes in four different states:
solid, liquid, gas, and plasma. Each of these states have certain properties that will tell
us how the matter will behave. These properties come from all the way down at the atomic level.
Remember in the last lesson when we learned that all matter was made up of teeny tiny atoms? Well,
it's how these atoms are arranged that will tell us what state the matter is in.
Let's take a look at solids first. A pencil, a baseball, and the device you're currently using
to watch this video are all great examples of solids. Solids all have a definite or fixed volume
and shape. Think about it this way; this rock is a solid, right? Unless an outside force acts on it,
it will always keep its same rocky size and same rocky shape. The reason for the rock's
definite shape and volume is the arrangement of its atoms. A solid's atoms are packed extremely
close together. Now, let's learn how the atoms in a solid move by observing this rock.
Fascinating. Now, you might think that solids don't really move much - and you'd be right - but
once again, if we take a much closer look, you'll see that the atoms are actually moving. Now,
the atoms are really packed tightly together so they can't move much,
but the atoms in a solid are all constantly vibrating just a little bit. You can think of
solids like a really tightly packed elevator. The people in the elevator are all cramped in there
so they can't really move, but they're all still kind of shuffling around just to get comfortable.
So, solids have a fixed shape and volume, their atoms are packed very closely together,
and they're always vibrating. Hmm, what examples of matter in the solid state can I think of?
Well, a donut is a solid, my pencil sharpener is a solid, and those really cool glasses that
I got for the last lesson are also a solid. Why don't you pause the video here and jot
down some of your own examples of the solids you can see around you in your guided notes.
If you've had anything to drink today then you have already come across our next state of matter,
liquid. Things like juice, syrup, oil, and lotion are all typically in the liquid states when we
use them. Liquids have a definite volume, so they always take up the same amount of space. However,
they don't have a fixed shape. If you pour a liquid into a cylindrical container,
it will take the shape of a cylinder. Pour it into a bear-shaped container and it'll take the shape
of a bear. Liquids take the shape of whatever container they're in. This is because the atoms
in a liquid are more loosely packed than a solid. Because the atoms are more spread out, they can
move faster and they're able to slide past each other. This is what allows a liquid to flow and be
poured, like when you pour milk into your cereal bowl. If solids are like a crowded elevator, then
liquids are kind of like a race; it's still pretty crowded, but people are able to pass each other
or fall behind and they are definitely moving faster than those people stuck in the elevator.
To recap, matter in the liquid state has a definite volume but no definite shape. Its
atoms are more loosely packed, allowing them to move faster and slide past each other.
Pause the video now and write down some examples of liquids in your guided notes.
Our next state of matter is gas. Gas constantly surrounds us. We use helium gas to fill up
balloons, steam gas to iron out the wrinkles in our clothes, and of course, we all rely on
the oxygen gas in the atmosphere to breathe. Gases have no fixed volume or shape. In fact, gases will
expand into whatever space is available to them, whether that's a car's tires or an entire room.
Gases behave this way because their atoms are very spread out. The atoms are moving
super quickly past each other. They're kind of like kids running around the playground;
they're spread out, they're moving quickly in every direction, and they might sometimes
bump into each other but that doesn't happen too often. So, gas has no definite volume or shape;
its atoms are all spaced out and moving around really quickly. Pause the video now to come up
with some of your own examples of matter in the gas state in your guided notes.
Solids, liquids, and gases account for most of the matter that we see here on Earth. However,
about 99 percent of all matter in the universe is actually in the fourth state of matter - plasma.
Plasma is the outcome of adding a lot of energy to a gas, usually in the form of heat. All that
energy causes pieces of the atoms themselves to break off, resulting in something like an
electrified gas. The sun and other stars in our universe are mostly made of plasma. However,
we can see examples of plasma here on Earth in things like lightning, fire,
and the Aurora Borealis, also called the Northern Lights. There are also artificial
examples of plasma here, too, like in neon signs or fluorescent light bulbs.
Now that we've explored the states of matter,
let's review everything we learned today. We now know that matter exists in four states:
solid, liquid, gas, and plasma, although that one is a lot less common to find on Earth.
Each state of matter has properties that determine how it behaves. A solid has a definite volume and
a shape and its atoms are tightly packed and slightly vibrating. A liquid has a definite
volume but not a definite shape. Its atoms are more loosely packed and they flow past each other
with more speed. And a gas has no definite volume or shape. Its atoms are spread out,
moving quickly past each other. To find out more about the states of matter, be sure to check out
the activities and practice questions that go with this lesson. All right, that's it for me today.
Thank you so much for joining us and remember, science is all around us. See you next time!