hi and welcome to the section of the chemistry tutor in this section we're going to cover an incredibly central part of chemistry very very important that's the concept of the atomic theory of matter in this section I'm going to explain what the atomic theory of matter is to you give you a few things that are incredibly important for you to know in the next section we're going to apply what we've done here and work a lot of problems to give you some some good confidence with what we're talking about the atomic theory of matter has a long history you can open your chemistry book and you can see what people have been trying to figure out the ideas behind matter and chemical reactions for a very long time because after all chemical reactions are all around us you can see that iron rust you can see lots of other chemical reactions so through the centuries people have been trying to figure out how this stuff works how do you think combined how do things change from one substance into another so there was a whole part of history in alchemy where people were trying to convert something you know lead into gold for instance so they could become a rich and so on so throughout the ages people put forth different theories for how substances basically react how do they change of course they didn't have microscopes they didn't have the internet they didn't have a lot of knowledge before them as far as getting on the right path so it's it's a really amazing that people were able to come up with these theories so long ago before the advent of what we would consider modern technology the first atomic theory that really made a lot of sense in comparison to what we know to be true is John Dalton's atomic theory so in your chemistry book you'll probably see a little historical section of how it all evolved but eventually you land on Dalton's atomic theory because that's really what we know too big to be more or less true so what we're going to start talking about here is Dalton's atomic theory and all that stuff now one thing I'll say before we get started don't get worried about it most of the stuff you already know we're just going to formulate it in a bulletproof way and the things that you don't know I promise you they'll make so much sense that you'll wonder why you didn't know them in the first place alright first thing is and I'm going to write these down because they're very very important I could just tell you but I think there's something to be by seeing it written down so for for John Dalton's atomic theory here we go here are the bullet points all matter and that means everything gases liquids wood metal every single thing you've ever touched is made of small particles called and you guessed it atoms and you know it's hard for us here in in the 21st century to realize how incredible of a jump this was for people to know that to be true because when you look at the sheet of paper absolutely nothing about it tells you that it should be made of small teeny tttt tiny little indivisible things we call atoms nothing at all they didn't have microscopes to be able to really examine them when microscopes were invented they were they were have very limited power and even today we have a hard time imaging individual atoms it's something that's not easy to do so to be able to come up with a theory and boldly say that everything is made of these things called atoms is a tremendous tremendous tremendous leap forward so that's bullet point number one okay second thing all atoms of a given element and when we say element we're talking about elements on the periodic table all atoms of a given element are alike in mass and other