hello greetings welcome to another video with me Miss Martins I'm a physical sciences and a math teacher so if you want to see more physics chemistry and math videos please let me know in the comments below what topic you want to see don't forget to give this video a thumbs up and subscribe so that I know that you want more things I'm planning on doing a whole exam prep Series where I go through past papers so let me know what you want to see in the comments below today we're going to go over the kinetic molecular theory a brief introduction I know some of you have been asking for this so let's do it the kinetic molecular theory says that all matter my coffee cup my cell phone me you your computer your phone whatever you're watching this on everything is made up of atoms and particles and particles are always moving even if you think they're not they are in a solid you may not see the particle movement but at a microscopic level atoms and particles possess kinetic energy which means they possess velocity which means that they are moving in a solid it might not be obvious but particles are vibrating in fixed positions as we move on to other phases of matter or states of matter like liquid gas plasma these particles gain more energy therefore the kinetic energy increases and the particles move faster it's these sort of things that you need to know and understand when it comes to the kinetic molecular theory but in a nutshell what you need to know is that movement how fast the particles are moving their velocity their kinetic energy that determines the phase of the matter whether it's solid liquid or gas here is a brief illustration of the differences between solid liquid and gas in solid States you can see the particles are close together higher density they packed in fixed positions they vibrate or move in fixed positions in liquid the matter maintains a fixed volume so if I pour water into a cup versus a box that liquid that water will take the shape that it'll make it'll mold itself to the volume to that shape of that container in a gas State however the matter expands to occupy whatever volume is available and that's why if you spray air freshener on the one side of the room the person on the other side may not smell it initially but give a Time those little particles expand to occupy the whole volume of the room in gases the particles also move very quickly bounce against the container walls bounce against each other and that's why the pressure for gases is higher you can compress gases but you can't compress a solid here's another illustration of a solid versus a liquid versus a gas now it's very important to understand that a state in which a substance exists so whether it's liquid solid or gas depends on the kinetic energy of its particles and kinetic energy is related to speed you will learn in further sections later on in grade 10 11 and 12 that kinetic energy the formula for kinetic energy is half times mass times velocity squared so you can see velocity is speed so how fast the particles move their speed determines the kinetic energy we know that gases the particles move a lot faster than solids for example and the intermolecular forces so those are the forces that hold particles together in solids and liquid phases in gas phases intermolecular forces are almost non-existent or very very weak now it's very important to note that temperature and heat are not exactly the same thing we won't really get into it into this video but the temperature of a substance is a measure of a particle's average kinetic energy or the the particles in the substances average kinetic energy that's very important you need to know that if we have a higher temperature the particles move a lot faster they have a higher kinetic energy now how do I make a substance change phase How does it go from a solid to a liquid to a gas that happens when I add heat or add energy now remember I did mention that heat is not exactly the same as temperature so I can add heat to a substance and its temperature can stay the same this sounds a little bit weird but when we do the heating curve it will make sense to you but for now just focus on the fact that if I add heat or energy if I increase it or if I decrease it I can cause a phase change see if you can fill in these phase changes with me so if I go from a solid to a liquid that is called malting okay so we take a solid think about ice if I go from solid ice solid water ice to liquid water melting if I go the other way around liquid to solid it's called freezing you do need to know the names of these phase changes within the kinetic molecular theory if I go from liquid to gas it's either called boiling think about boiling a kettle or it is called evaporation evaporation either or boiling or evaporation if I go the other way so a gas back to a liquid it's called condensation and we can see that inside a kettle when we boil something we see the little water droplets condensing the gas going back into a liquid form on the sides of the kettle then we've got if I go straight from a solid directly to a gas with no intermediate liquid phase in between so the keyword is directly that is called sublimation and you do need to know that sublimation and now I remember sublimation is we're going from a solid to a gas solid sublimation solid directly to a gas and then the reverse going from a gas back to a solid is called deposition so those are called phase changes phase changes and yes you do need to know them just be careful because if a question in the exam asks you to State the phase then you have to say solid liquid or gas if they say the phase change you have to give me malting freezing condensation one of those so I love this photo it kind of summarizes everything very very nicely and you can see that as I go from the solid face to the gas face I'm adding heat energy just so you know plasma is another phase of matter it's a state of matter in which gaseous substances become ionized and basically the electrons escape from the atoms and it leaves positively charged protons free electrons free Pro protons that is where we get the ionized gas phase and it's called plasma we also get this really cool thing just as a side note it's called Oobleck it's a non-Newtonian fluid or liquid and the state that of matter that it's in so whether it's more solid or whether it's more liquid depends on the pressure that you apply to the substance itself so if I squeeze the substance it becomes a solid if I relax the pressure if I remove the pressure it turns into a liquid let me know in the comments below if you'd like me to make some of this on my YouTube channel here of all the differences between solid solid liquid and gas they can ask this in an exam they can ask you to tabulate it they can ask you to list differences so I would pick three maybe four learn the differences and there we go you're all set for your exam in the next video we will be looking at the heating curve if you guys want it let me know down below if you'd like to see me go over the heating curve and don't forget to subscribe let me know whatever else you want me to do whatever else you want me to see on this channel I'm making content to help you guys so thank you for watching and I hope you enjoyed the video