All right we're going to get back in action here with another presentation and this time we're going to talk about states have matter and how substances can change from one state to another with a-changing owes energy and we'll get into that rate now so we're gonna basically be dealing with the three main states that matter.
There are five but we're going to deal with the basic three and I'm sure you are familiar with solids liquids and gases now I've used medals for all these so for solid and get some gold bars there for liquid have got some liquid mercury and you might wonder why I have a late Bob there this kind have labeled is actually called a mercury vapor light pole so there's actually vaporized mercury inside that late Bob so mercury as a gas and a I'm not going to get into the physics is how that works but so just want you to realize that quite often when we think I've stated matter we go to water it always seems to be water
Okay we talk about a sweet or liquid water we talk about steam so I want you to realize that most pure substances will undergo these changes as well not just water so will try to avoid using water as an example but I'm sure I won't be able to avoid it totally we'll see what happens so let's start by talking about the behaviour the particles when they're in different states have matter so we'll start with solid and here get a little animation and the little red dots they represent particles.
In a solid and he concedes these particles a packed tightly together okay so there is no room between the particles you can't be pushed together anymore and they're connected so they can't really be pulled apart either because the particles are should have attracted to 10 this what's called intermolecular bond now that's not as strong as a bond it's between Adams in a compound but this this bond does sort of keep these particles attracted to one another so since these particles are packed tightly together and they can't be pushed together a pull-apart they have a definite volume they can see the particles are sorted sitting there vibrating in place in this is obviously quite exaggerated but you give to you get the idea so the vibrating in place but they don't move around one another so the particles do not move relative to one another and what I mean by that so if we look at the top the particle in the top left hand corner.
I it stays where it is it doesn't move around you can see these other three particles that are near it they stay in the same position relative to one another they don't move around one another and it's all because that salads have a definite shape so this definite shape is because the particles do not move around one another so we take a look at liquids, its kind a similar to a solid in net those particles are packed tightly togetherso again they're packed really tightly together just like you were in a solid so they have a definite value they can't be compressed and they can't be expanded the one thing they do differently than a solid is those particles do move around one another in since they do that they take the shape of the container that they're in so they do not have a definite value and now look at gases and they're quite different from solids and liquids you can see the particles it kind a zip in all over the place and new space between them so it's very different the particles move around a lot like liquids but the the change position relative to one another but unlike liquid steers sorta there is space between those particles so the particles actually spread out as far as they can go so they actually take to shape up the entire container that there's stored in and they also take the volume up that container now if we could compress this container make it smaller the gas particles would still spread out and fill up the container but they were just getting you closer together and likewise if we were to able to make this container larger in expand the container those particles would move throughout their container and fill it up so the volume of a gas is not constant you can change it by changing the pressure on it or you know basically the size of the container that in in there are fewer famous gas laws that we're not going to get into but they do explain the relationship between the pressure on a gas in the volume a bit so now that we have an idea of how these particles behave
Let's talk about how we can change the behavior of particles so when the particles behavior changes the substance will change state so we can change is stated matter through the use of what's called thermal energy in what thermal energy is just a it's the energy that is substance has because the motion ovens particles so it's also can be thought of as heat energy it's often referred to is that and we can think of it as the faster the particles are moving harder the substances so only heat substances up the particles begin to move more in the move faster so they have a higher thermal energy and if we hit them up enough they're gonna change from one state to another so if we look at the animations that we had before here's that solid in that substances at a low temperature but if we are to raise the temperature of that substance to high temperature the particles move around a lot faster and this would represent a gas so that same substance at a higher temperature had the particles are moving faster has more thermal energy and it's in a different states so let's take a look at an animation is shooting a substance up and changing it from one state to another so here we have some particles and we're gonna increase the thermal energy and it's going to cause a change in state CC little blue bar rising there and a as that rises the temperature is representing the temperature rising so watch the particles move a little bit faster in pretty soon they're going to sort a break free of one another and once they do that melting will start to occur and you'll notice that when it reaches the melting point rate about here the temperature stops changing in the particles go into a liquid state so their first broke the broken free if one another in their moving around one another and now that it's all liquid the temperature can continue to rise in 12 reaches the boiling point .
You'll notice the temperature stops again in the particles begin to break free up the liquid and rise up into a gas state and that temperature again stay
there until all the liquid is gone in its all a gas in the reason for the that temperature staying the same is it would be impossible to have a solid at a temperature higher than its melting point so until all that solid is gone that substance is going to stay rate at the melting point and once it all the
the entire substance reaches the melting point it would be all liquid so someone that substance begins to become a gas but until all if it becomes a gas the temperature can rise past that boiling point because there's still some liquid there that's hasn't gone above the boiling point it's a little weird but I think a summer the activities that we didn't class would probably help clarify that a little bit so let's take a look at some of the types of changes that matter can go through the first one will talk about is freezing I think we're all familiar with that it's where a liquid becomes a solid so it's important to remember what has to happen for that to occur is you need to decrease the thermal energy of the substance so we're decreasing the motion of the particles until their they slow down enough in there if they don't move around one another freely anymore know the type to change we looked at was mounting so here we have a solid becoming a liquid so we increase the thermal energy the particles in a solemn any causes them to you break free of one another in move around the container a little bit more vaporization is what occurs when a liquid becomes a gas so we increase the thermal energy of the particles enough in that substance where they break free love one another in come out in the liquid state and they've particles begin to fly around one another and condensation is where liquid becomes a gas now the picture that we have here is something is probably familiar to everyone you know when you get on the shower usually the mirror is covered in water the reason for that is when you're in the shower here you've got hot water and some that hot water becomes a vapor and it's floating around in the air in the bathroom in when it gets near the class if the mirror the class is called so it cools that gas down enough where the particles become a liquid again so what you end up having on the on your mirror their is a sorta she dove liquid water so we've decrease the thermal energy than gas to make it become a liquid the next two types of changes might not be quite as familiar to you there's something called sublimation and that's when a solid becomes a gas so we increase the thermal energy have a solid enough in quick enough where it will become a gas right away so it doesn't go through that melting stage not too many substances do this very easily but one that you're probably very familiar with is something called dry ice.
I'm sure you've seen that before what dry ice is frozen carbon dioxide so carbon dioxide undergoes sublimation relatively easily so what ends up happening to this frozen carbon dioxide is the particles that are on the surface of the solid break free of the solid quickly and escape is a gas without going into a liquid state now I referred to this is dry ice before in the reason I referred to it is dry ice was because that's exactly what it is it's ice that doesn't melt it just turns directly into a gas so it sub lines would be the word so you can pack things in in dry ice and rather than the ice melting in becoming a liquid in making a mess.
I love everything it just turns directly into a gas and everything stays dry hence dry ice now the opposite of sublimation is something called deposition it's also referred to as crystallization this is where gas becomes a solid so you've got a rapid decrease in thermal energy again you might not think you're very familiar with it but if you've ever woken up on a cold morning and seen this on your window that's what happened there was water vapor in the air either inside or outside of the house and it got to a cold window and rather than sticking to the win on becoming a liquid and then becoming a solid it went directly into the solid-state so no need to talk about the output page for this presentation what I want you to do is I want you to create a diagram that shows the different changes from one state manner to another and again we're only going to deal with solid liquid gas so I want you to you know come up with the diagram and I'll give you sort of a little a very very basic version of what I think you might come up with because you know I want you to do your work and be creative so maybe you could have solid liquid and gas in you know maybe use images for this and what you could do is so drawn lines between these game I've done here is a dues blue lines to represent decreasing thermal energy in red lines to represent increasing thermal energy so maybe on those lines you can actually put what that change would be so where it got the red line going from solid to liquid maybe I could label that melting because that would be the phase change that occurs when the thermal energies increased a solid when it becomes liquid I hope that makes sense and if it doesn't we can talk about it in class tomorrow or we can use at moto or whatever else we want to do to get this thing done