in this video we're going to talk about the different phases of matter these are sometimes also referred to as the states of matter so in the world around us they're all different kinds of stuff and there's a scientific word for stuff we call it matter matter is stuff anything that takes up space and has mass now has mass might sound a little unfamiliar so that just means that it weighs something all this stuff takes up space it weighs something so it's matter now if we look at all these different examples of matter we can put almost everything into one of three categories matter can be a solid a liquid or a gas these categories are known as the phases of matter now you might also know that there's some unusual phases of matter like plasma but we're not going to worry about those here now I bet you're pretty familiar with each of these phases from everyday life but we're going to look at them in a little bit more of a scientific or technical way well first look at some of the big picture characteristics of the different phases and then we'll look at a microscopic view of each phase we'll start with solids here's some examples a cube of metal a rock a bar of gold now we all sort of know what a solid is but how would you really Define it right a solid is hard a solid is solid well technically speaking we'd say that what makes a solid unique is that it has a definite shape and a definite volume definite means that it's certain that it can't easily change all these solids unless we bang them or crush them the shape isn't going to change that's what makes it definite and volume refers to the amount of space that something takes up and for a solid volume is definite too for example the cube has these dimensions of one centimeter by one centimeter by one centimeter its volume is one cubic centimeter move this Cube around roll it around the volume won't change it's definite now another important characteristic of solids is that they're incompressible this means that you cannot squeeze them into a smaller volume or a smaller amount of space you can try you can exert Force but it's not going to happen so these are the big picture characteristics the defy a solid now let's zoom into the solid and get a microscopic view zoom into anything billions and billions of times you'd see that it's made of tiny particles and for our purposes right now we'll show these as little circles or little balls here are the particles that make up this solid there are a couple things to point out first we see that they're closely packed together and we can't show it here but these particles would actually be moving they'd be vibrating in place sort of quivering here's a diagram just moving back and forth but these particles are fixed or stuck in one spot they're not moving around they're not moving to new locations they're just vibrating or jiggling in place that's very important here for the behavior of particles in a solid now the way these particles behave that affects the big picture characteristics okay so for example the reason why solids have a definite shape is because the particles in a solid are fixed in one spot they're stuck in one position right in order for the cube to change shape the particles that make it up would have to move into new locations imagine a brick house the bricks are kind of like the particles you can't easily push a brick house into a new shape because of the individual particles the individual bricks can't move it's the same way with the particles in a solid definite shape and as we said earlier solids are incompressible well now you can see why there's not really any extra space between the particles so even if you exert Force you can't pack the particles more closely together so you can't compress the solid so here's everything that we've learned about solid so far we'll build a nice little table for the different phases of matter and we'll move on to liquids okay so here we've got some what makes a liquid a liquid well technically a liquid has an indefinite shape but a definite volume let's see what that means a liquid flows freely it takes the shape of its container like this flask here the liquid has the shape of whatever container it's in so every time we pour this liquid into a new container like a glass or a bottle or a beaker it takes on a different shape that's why we say that shape is indefinite but the liquid still has a definite volume for instance in each of these containers here the shape changes but the volume the amount of space that the liquid takes up is the same 750 milliliters the volume doesn't change it's definite even though the shape does and liquids are incompressible this sometimes surprises people but it's true if you put a liquid in a syringe like this and you seal the end you cannot squeeze this plunger down the liquid just won't compress so you can't squeeze a liquid into a smaller volume and obviously these big picture characteristics that we talked about are true for all liquids now let's zoom in and see what the particles would look like in a liquid now compared to the particles of a solid you can see that the liquid particles are still pretty close together but there's a big difference in movement here the particles in a liquid are constantly moving around in a solid they're stuck vibrating in place but in a liquid they kind of swim or wiggle past each other you can kind of see that here in the diagram and as before there's a link between the behavior of the particles and these characteristics liquids have an indefinite shape because the particles can move around they can move into new locations that's how liquids pour all the particles just kind of tumble over each other and then move into a new shape or a new layout but we can see why liquids are still incompressible like solids the particles might be a little bit looser than in a solid but they're still not really much space between them so it's hard to squish them together any closer they remain incompressible and here now is everything that we've talked about with liquids we'll move on to our last phase of matter gases now gases can be a little bit weird because most of them are invisible like air only a few gases have a collar that you can see and sometimes people feel that gases aren't really matter but they definitely are gases take up space think of this balloon and gases have mass they weigh something a balloon full of air weighs more than an empty balloon SO gas is fulfilled both of these characteristics they're definitely matter okay so now for some specific characteristics a gas has an indefinite shape and an indefinite volume like a liquid the shape of a gas will change to fit any container that it's in so that's why the shape is indefinite but the volume of gas also changes right now the gas is taking up the volume of this flask but if we remove the top the gas would expand it would come out to fill up a larger volume gases can expand or contract to fill a container that's why the volume is also indefinite and unlike the other two phases of matter that we talked about gases are indeed compressible in a situation like this you exert some force on the top of this syringe and it compresses the gas you can squeeze it into a smaller volume and this is a summary of those characteristics now let's zoom in on our gas check it out particles are really far away from each other and we'd see that they are in constant rapid motion they're flying around really fast gases have an indefinite shape just like liquids because the particles can move around into new locations they also have an indefinite volume they can expand and contract and that's because these particles are far apart and they're constantly flying around when they have more space to take up the particles just fly further apart or give them less space and they can come in closer and now you can see why solids and liquids have a definite volume the particles are kind of stuck closely together and they don't separate they don't really come apart even though the particles in a liquid move around they don't really spread far apart from each other so these two phases of matter can't expand to take up more space and remember they're not compressible either so they can't contract to take up less space and that leads us to compressibility for gases gases are compressible because the particles are so far apart there's lots of extra space between them and it's very easy to squeeze them into a smaller volume here's our complete chart and now let's do a quick review everything we talked about first matter is anything that takes up space and has mass its physical stuff and these three phases of matter have different characteristics a solid has a definite shape and a definite volume its particles are closely packed together they vibrate in place but they don't move around solid is hard to compress a liquid has an indefinite shape but a definite volume it takes the shape of its container its particles are close together but they do move around liquids can flow but they're hard to compress and finally gases have no definite shape and no definite volume they take the shape and the volume of their container the particles in the gas are very far apart and they're flying around really quickly because there's a lot of space between the particles gases are easy to compress so that's an introduction to the three main phases of matter