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Current time:0:00Total duration:13:09

Video transcript

we humans have known for thousands of years just looking at our environment around us that there are different substances and these different substances tend to have different properties and not only do they have different properties one might reflect light in a certain way or not reflect light or be a certain color or be have a certain at a certain temperature be liquid or a gas or be a solid but we also start to observe how they react with each other in certain circumstances and here's pictures of some of these substances this right here is carbon and this is in the in its graphite form this right here is lead this right here is gold and all of the ones that I've drawn that I've shown pictures up here and I got them all from this website right over there all of these are in their solid form but we also know that we it looks like there's certain types of air and and you know certain types of air particles and depending on what type of air particles you're looking at whether it is carbon or oxygen or nitrogen that seems to have different types of properties or there's other things that can be liquid or even if you raise the temperature high enough on these things you could if you raise a high temperature high enough on gold or LED you could get a liquid or if you if you kind of if you if you burn this carbon you can get it to a gaseous state you can release it into the atmosphere you can break its structure so these are things that we've all kind of that that humanity has observed for thousands of years but it leads to a natural question that would used to be a philosophical question but now we can enter it a little bit better and that question is is if you keep breaking down this carbon into smaller and smaller chunks is there some smallest chunk some smallest unit of this stuff of this substance that still has the properties of carbon and if you were to somehow you break that down even further somehow you would lose the properties of the carbon and the answer is there is and so just to get our terminology we call these different substances that these pure substances that have these specific properties at certain temperatures and react in certain ways we call them elements we call them elements carbon is an element lead is an element Gold is an element you might say that water is an element and in in in history people have referred to an element but now we know that water is made up of more basic elements it's made of oxygen and of hydrogen and all of our elements and all of our elements are listed here in the periodic table of elements C stands for carbon I'm just going through the ones that are very relevant to humanity but over time you'll probably familiarize yourself with all of these this is oxygen this is nitrogen this is silicon this is au is gold this is lead and that most basic unit of any of these elements is and that is the atom is the atom so if you were to if you were to keep digging in and keep taking smaller and smaller chunks of this eventually you would get to a carbon atom do the same thing over here eventually you would get to a Gold atom you did the same thing over here eventually you'd get some this little small for lack of a better word particle that you would call a lead atom and you wouldn't be able to break that down anymore and still call that lead it for it to still have the properties of lead and just to give you an idea and this is really something that I have trouble imagining is that atoms are unbelievably small really unimaginably small so for example carbon my hair is also made out of carbon in fact most of me is made out of carbon most of in fact most of all living things are made out of carbon and so if you took my hair and so my hair is carbon my hair is mostly carbon so if you took my hair right over here and my hair isn't yellow but it contrasts nicely with the black my hair is black but if I did that you wouldn't be able to see it on the screen but if you took my hair here and I were to ask you how many carbon atoms wide is my hair what is the dye so if you took a cross section of my hair not the length the the width of my hair and said how many carbon atoms wide is that and you might guess Oh me you know I salary told me it's a it's a they're very small so maybe there's a thousand carbon atoms there are ten thousand or a hundred thousand I would say no there are 1 million carbon atoms or you could string 1 million carbon atoms across the width of the average human hair and that's obviously an approximation it's not exactly 1 million but that gives you a sense of how small an atom is you know like a hair out of your head and just imagine putting a million things next to each other across across the hair not the wit not the length of the hair the width of the hair it's even hard to see the width of hair and there would be a million carbon atoms just going along it now it would be pretty cool in in and of itself that we've we do know that there is this most basic building block of carbon this most basic building block of any element but what's even neater is that those basic building blocks are related to each other that they're that eat a carbon atom is made up of even more fundamental particles a gold a gold atom is made up of even more fundamental part fundamental particles and depending and they're actually defined by the arrangement of those fundamental particles and if you were to change the number of fundamental particles you have you could change the properties of that element how it would react or you could even change the element itself and just to understand it a little bit better let's talk about those fundamental elements so you have the proton you have the proton and the proton is actually the defining the number of protons in the nucleus of an atom and I'll talk about the nucleus in a second that is what defines the element so this is what defines an element of the when you look at the periodic table right here they're actually written in order of atomic number and the atomic number is literally just the number of protons in the element so by definition hydrogen has 1 proton helium has two protons carbon has 6 protons you cannot have carbon with 7 protons if you did it would be nitrogen it would not be carbon anymore oxygen has 8 protons if somehow you were to add another proton to there it wouldn't be oxygen anymore it would be fluorine so it defines the element it defines the element and the atomic number the number of protons number of protons and remember that's the number that's written right at the top here it for each of these elements in the periodic table the number of protons is equal to the atomic number is equal to the atomic number it's a suit and they put that number up here because that is the defining characteristic of an element the other two constituents of an of an atom I guess we could call it that way are the electron are the electron and the neutron and the neutron and the model you can start to build in your head and this model as well as we go through chemistry we'll see can again it'll get a little bit more abstract and really hard to conceptualize but one way to think about it is you have the protons and the neutrons that are at the center of the atom there the nucleus of the atom so for example carbon we know has six protons so one two three four five six nor carbon-12 which is a version of carbon will also have six neutrons you can have versions of carbon that have a different number of neutrons so the neutrons can change the electrons can change you can still have the same element the protons can't change you change the protons you got a different element so let me draw a carbon-12 nucleus so one two three four five six so this right here is the nucleus of carbon-12 and sometimes it'll be written like this and sometimes they'll actually write the number of protons as well and the reason why we write it carbon-12 you know I kinda doubt I counted out six neutrons is that this is the total you could view this as the total number of one way to view it and we'll get a little bit nuanced in the future is that this is the total number of protons and neutrons inside of its nucleus and this carbon by definition has an atomic number of six but we can rewrite it here just so that we can remind ourselves so at the centre of a carbon atom we have this nucleus and carbon-12 will have six protons and six neutrons another version of carbon carbon-14 will still have six protons but then it would have eight neutrons so the number of neutrons can change but this is carbon-12 right over here and if carbon-12 is neutral and I'll I'll give a little nuance on this word in a second as well if it is neutral it'll also have six electrons so let me draw those six electrons one two three four five six and one way and this is maybe the first order way of thinking about the relationship relationship between the electrons and the nucleus is that you can imagine the electrons are kind of moving around buzzing around this nucleus one model is you could kind of thinking of them as orbiting around the nucleus but that's not quite right they don't orbit the way that a planet's a orbits around the Sun but that is a that's a good starting point another way is to kind of they're kind of jumping around the nucleus or they're buzzing around the nucleus and it's just because reality just gets very strange at this level and will actually have to go into quantum physics to really understand what the electron is doing but a first mental model in your head is at the center of this atom of this carbon-12 atom you have this nucleus you have this nucleus right over there and these electrons are jumping around this is this nucleus and the reason why these electrons don't just go off away from this nucleus why they're kind of bound to this nucleus and they form part of this atom is that protons have a positive charge have a positive charge and electrons have a negative charge and it's one of these part it's one of these properties of these fundamental particles when you start thinking about what is a charge fundamentally other than a label and it starts to get kind of deep but the one thing that we know when we talk about electromagnetic force is that unlike charges attract each other so the best way to think about it is protons and electrons because they have different charges they attract each other neutrons are neutral so they're really they're really just sitting here inside of the nucleus and they do affect the properties on some level of some of these for some at for some atoms of certain elements but the reason why we have the electrons not just flying off on their own is because they are they are attracted they are attracted towards towards the nucleus and they also have an unbelievably high velocity it's actually hard for and we start touching once again on a very strange part of physics once we start talking about what an electron actually is doing but it has enough its I guess you could say it's jumping around enough that doesn't want to just fall into the nucleus I guess is one way of thinking about it and so and so I mentioned carbon-12 right over here defined by the number of protons oxygen would be not defined by having eight protons but once again electrons can interact with other electrons or they can be taken away by other atoms and that actually is forms a lot of our understanding of chemistry is based on how many electrons an atom has or a certain element has and how those electrons are configured and how and how this and and how the electrons of other elements are configured or maybe other other atoms of that same element we can start we can start to predict how an atom of one element can react with another atom of that same element or an atom of one element could begin how it could react or how it could bond or not bond or be attracted to a repel another atom of another element so for example and we'll learn a lot more about this in the future is it is possible for another another atom someplace that to swipe away an electron from a carbon just because for whatever reason it's it's and we'll talk about certain elements certain neutral atoms of certain elements have a larger affinity for electrons than others so one may be one of those swipes and electron away from a carbon and then this carbon will be having less electrons than protons so that would have five electrons and six protons and then it would have a net positive charge so in this carbon-12 the first version I did I had six protons six electrons the charge is canceled out if I lose an electron that I only have five of these and then I would have a net positive charge and we're going to talk a lot more about all of this throughout the chemistry playlist but hopefully you have an appreciation that this is already starting to get really cool once we can argue we can already get to this really fundamental this fundamental building block called the atom and what's even neater is that the this fundamental building block is built of is built of even more fundamental building blocks and these things can all be swapped around to change the properties of an atom or to even go from an atom of one element to an atom of another element