hey my name is kayleigh and in this lesson we're going to learn about how heat
affects matter make sure you know the basics of matter by watching the video
what is matter let's get started
every gas fluid and solid thing is made up of matter and matter is made up of
tiny particles called atoms and molecules matter can exist in different
states you may have already studied some of these states we will focus this
lesson on the three most common states of matter solid liquid and gas this
simulation is from C k12 we can see how matter acts differently as a solid
liquid and gas the solids hold their shape and volume when moved to a new
container of a different shape in size
the liquid flows it changes shape to fit the new container but the amount of
space it takes up or the volume stays the same the gas acts much differently
once the lid is lifted the gas particles move to take up as much space as
possible some molecules don't even make it into the new container gases don't
keep their shape or volume when moved to a new container so let's act the way
they do because the atoms and molecules that make up their matter are tightly
packed together usually in a pattern and they hardly move they may vibrate or
jiggle but for the most part they are fixed in place that is why it is so hard
to compress or squish a solid liquids are able to flow and change their shape
because the atoms and molecules are not fixed they're able to slide pass each
other and they move faster than particles in a solid the particles in a
liquid have more free space between them than in a solid this makes it easier for
a liquid to flow and change shapes but since the particles are still close
together a liquid is hard to compress make smaller gases are able to change
their shape and their volume because the atoms and molecules can move freely
particles in a gas can vibrate but they also move at really high speeds there's
a lot of free space between gas particles and that's why it's easy to
compress a gas we can change the state the matter is in this is called a
transition recall that there are four main transitions melting which happens
when heat is applied to a solid and it transitions to a liquid freezing which
happens when a very cold temperature is applied to a liquid and it transitions
to a solid evaporation happens when heat is applied to a liquid and it
transitions to a gas and condensation happens when cold temperatures are
applied to a gas and it transitions to a liquid do you notice anything about all
four of these transitions every transition is caused but if I change in
temperature and a change in temperature is what we refer to as a change in
thermal energy if you've watched our videos on energy you may know that
energy cannot be created or destroyed so when atoms and molecules have
increased thermal energy they move faster this is called an energy transfer
but - what kind of energy kinetic energy the energy of motion
let's have over to a Phet game to see what effects thermal and kinetic energy
have on the states as matter so here we are in the Phet sim called states that
matter basics and we're in the second game called phase changes and you'll see
we have four different atoms and molecules that we can choose from and
there's also this handy phase diagram that we will use I'll show you how to
read it we can change the temperature here we have a thermometer here let's
either in Celsius or Kelvin we'll use Celsius we're going to use water and
really well no some of those temperature points there's also a pressure gauge
here so that's our compressibility with this finger we can push the lid up or
down and we also have a pump here that you can add by lifting it up and
bringing you back down more molecules into your container alright so let's get
started and see what happens with water I'm just gonna point out here with
Celsius the freezing point is zero so that would mean the water will be a
solid and as you can see here wherever the red line is that is what phase we
are in so this black dot will be when our solid turns to a liquid and up here
our liquid into a gas so here we see our red dot is still on the solid point so
as you can see our water molecules are vibrating and jiggling but for the
most part maintaining their shape so let's increase the temperature here see
I can lift it up and then bring it back down and then if I bring it back to that
zero point it holds it steady so now I'm at 1 degree Celsius at zero degrees is
the transition between solid and liquid so you can see now that our molecules
are moving a little bit faster and they're kind of spreading out right
they're taking up the shape here and what happens now if I bring the
temperature down look at these molecules how they're moving if I bring the lever
down let's say the negative 80 degrees Celsius what happened to the speed that
my molecules are moving with it's less now see they're just kind of barely
vibrating so let's add some heat again so I'm increasing my thermal energy I
made it 13 degrees Celsius now you see they're moving a little bit faster
they've spread out into the shape more of how a liquid would look now let's add
some more and see how their kinetic energy so how fast they're moving
changes so now I'm up here at 96 degrees Celsius so now I'm moving pretty fast
you'll see some of them are even getting an extra
boost because they're moving so fast they're spinning and you see how they
have a little bit more freedom they can slide past each other but right now I'm
still as a liquid just some of them are getting an extra boost let's see what
happens as we compress our liquid water so if I go down to kind of the beginning
of where they are you'll see my pressure is going up what happened to my
temperature my temperature is also increasing so that's because as this
pressure goes up the temperature increases and my little molecules are
moving even faster now so let's relieve our pressure on our
liquid water so I'll see my pressure gauge is going back down but these guys
are still moving pretty fast right my temperature was increased from that
let's add some more thermal energy so I'm turning up the temperature here you
see what's happening to my molecules are they moving faster or slower
yeah fast are they moving crazy and they're taking up a lot more space and
looking over at my phase diagram graph over here it looks like I'm just now
hitting the gas phase so I'm right at that transition point and I'll see these
guys are moving freely there's much more space between them now what happens if I
try to compress my water molecules as a gas
so my temperature increase my pressure increase the speed of my molecules
increased I can take you down a little more wow I got some really hot temps in
here my pressure is going up but look at how I can increase the pressure I can
compress my water molecules but my pressure gauge is kind of bouncing back
and forth but its overall getting lower because as a gas I can compress it even
more because there's space in here between these particles good let's lift
this back up so now you get a chance to play around with this you can use all
four of the different ones they all have different transition point temperatures
and you get to explore what they look like in their different states you've
learned so much science in this lesson keep exploring the states of matters
with our game and activities and have fun and remember to always be clever