 We have this glass of water and we will submerge this stone inside the water and when we do that we must have seen that the level of the water rises, right? Even if you insert your finger in this in this glass of water, the level of the water will rise. But now if we have the same glass of water and if we now put in some salt, some salt into it and we start mixing it. After some time the the color of the water might change. It will seem a little a little cloudy. But the level of the water will not rise. Why is that? Isn't salt matter? Well, just like just like the piece of stone. It's also solid, right? So why isn't the level of the water rising? Well, to answer that we'll have to zoom in. So when we zoom in we see we see water molecules and I'm showing that showing that like this. We have all these water molecules and there are there are some spaces in between these water molecules and the salt the salt molecules they occupy the spaces between the water molecules. So when the salt dissolves it occupies the spaces in between the water molecules and the level of the water does not rise. Now this really shows this really shows that particles of matter have space between them. Alright, now let's look at some more some more common daily life examples. Whenever there are some incense sticks burning in a room you must have felt that as soon as they burn you can start smelling the incense sticks. Why does that happen? Also, if if you dissolve if you dissolve something in water like let's say if you place a compound like potassium permanganate, it starts moving around in water. Or if I if I try to mix this food color in water, look at how the food color starts moving inside the water. Finally, you also must have seen dust particles dancing around whenever sunlight is coming into your room through a window. Again, why does this happen? So all of these examples, they really show they really show that particles of matter they are moving they are moving continuously. Particles of matter are continuously moving and especially in a liquid or a gas a particle of matter will move in any random in any random direction. That is why you see dust particles dancing around because they are colliding with the particles of the air and you can understand how the particles in air move just by looking at how the dust particles are moving. Dust particles are moving randomly because they are constantly colliding with the air particles. Now because the particles are continuously moving, we say that they have a certain kinetic energy of their own and because they have a kinetic energy they have a certain temperature. Every every substance have has a temperature of its own. If you increase the temperature the particles start moving faster. That is their kinetic energy increases. Now if you think about a solid, if you think about a piece of stone particles aren't really moving in this solid like they do in fluids that is gas or liquids. But particles are still vibrating at their positions. They are still vibrating at their positions. If you zoom in that is how the particles will behave. They are still vibrating. If you increase the temperature, they will vibrate even faster. This is a reason why a potassium per magnet started moving around in water because every particle of potassium per magnet is striking a particle of water and that is helping it mix or spread throughout the body of the water. The same reason why we can smell incense sticks whenever they are burning in any corner of a room. Now we can talk about one more thing over here and that is when potassium per magnet is mixing in this body of water. Let's see what's really happening. Let's try and zoom in. So when we zoom in, when we zoom in, we have, we have these particles of particles of water. They're all these particles of water and potassium per magnet takes up the space between these water molecules. It takes up the space between these water molecules. Now not just in this example, even the other three examples that we saw, particles of matter are mixing on their own with each other and they do this by getting into the spaces between the particles. This intermixing of particles of two different types of atoms is called diffusion and it happens on its own. So the particles of the incense sticks, they took up the space between the air particles, which then they are all continuously moving, the particles of potassium per magnet, they take up the space between the water molecules. So we can say that diffusion is happening here. Alright, now lastly whenever you throw water on the floor, you must have seen water getting collected like this on the floor. Why does this happen? Well, turns out particles of matter, they have, they really pull each other or we can say attract each other and these forces, they attract, they attract each other with a force. These forces are called intermolecular forces. So that is why, that is why one of the reason of a raindrop being spherical is because all the particles of water, they are pulling, they are pulling each other. They are pulling each other and that makes the raindrop take up a spherical shape. You will learn more about this in physics under the topic surface tension. But every particle of matter, they attract each other. They have these intermolecular forces. They are pulling each other with some force. Alright, so these three are the characteristics of particles in matter. They have spaces between them. They are continuously moving and they attract each other.