Boop. It started in a few just whenever the projector decided it wants to project. I hear it, just...
speak to determine like every lecture i have to call instructional support because there's something that'll work My name is Alex Estrada and SBSB 2111. I need a hand. I'm trying to get the projector going, but it ain't going. Yeah, pretty much I have it displaced at the on. It's on PC and it's not playing anything on the projector. Let's give it a light.
It's running. We should be going. I didn't seem to be doing much. 11, yep. Yeah, appreciate it.
Thank you. Okay, well then I guess we got to do with the old fashioned. For now we'll avoid technology because it doesn't seem to agree with me.
There's a couple more things I want to touch on for chapter one before we formally get started into chapter two. First one is really kind of dealing with units and how we handle units and calculations. For example, we've been talking about this whole dimensional analysis thing.
So if I were to put 17.5 centimeters and convert this over to meters, well, there's, let's see, it's 10 to the minus 2 meters and 1 centimeter. You could also write this. This is if you really wanted to think about it in a different way. this is the same thing as one meter contains 100 centimeters, right?
So it's 10 to the minus 2 with minus 2 on top, or this is also functionally the same as 1 over 10 to the square meters. There's all different ways of writing the same mathematical expression, and just like we've been talking about, if you take two units and divide them into each other, they cancel out. Why?
Because anything divided by itself is equal to one, right? So centimeter divided by centimeter is equal to one. It's kind of the same idea as what we've been, as what you've learned about when tackling, um, same idea as what we've been talking about in terms of what you learned about in terms of variables.
So what do I mean by that? Well, if you take x times x, what is this? x squared, right?
x squared. And of course, if you take x divided by x, as I just mentioned, this is one. What if you take x cubed and divide it by x?
What's the answer here? X squared. Very good. All right.
So, likewise, if I were to give you something that is, say, I don't know, centimeters cubed and divided by centimeters, what is my unit right here? Centimeters squared. Excellent. Okay.
So, with that in mind, what if I told you that this room is, I don't know, I'm going to make up a number here, 6.83 meters cubed, and I wanted you to convert this into milliliters, all right? There's one thing I kind of glossed over, and I talked about it a little bit before. It's certainly in your book, but the main idea is that for this, you're going to need a couple of conversion factors. And the one that's kind of hidden, the one that isn't really well known, is that one centimeter cubed is equal to one milliliter. So one cubic centimeter is one milliliter, and this is exact.
So infinite sig figs there. Those of you who are perhaps looking into nursing or something like that, A cubic centimeter cc is a milliliter. So you know or you're watching I don't know House or something is like get like 50 cc of whatever. That's what he means.
He just means 50 milliliters. All right. So, okay, good. In there.
So, how do I even approach this? Right. Well, we already know, we kind of have a guess that to go from meter cubed to milliliter, we're going to have to take a little pit stop at centimeter cubed. Right. Okay.
So, let's go ahead. 6.83 meter cubed. And what do you reckon might be my first dimensional analysis step here? But it's what?
So, okay, we want to work towards centimeters cubed, right? Unfortunately, something like this, not quite so easy, right? Well. Actually, it is kind of easy.
I can tell you right now it's, let me think, there's 100 centimeters per meter, so 1, 0, 0, 0, 0, 0, 0. I could tell you that in one meter cubed, there's 1, 1, 2, 3, 4, 5, 6 centimeters cubed. Yes. Like it was a projection? Yes, over here. Okay.
Thank you. So. I could tell you this, and you could commit this to memory if you so chose, but why would you, right? You guys already have these fancy SI prefix table that you guys have already memorized. What the hell?
How? Cool. I swear I'm not an idiot. No, no, no, not at all. This happens all the time.
Okay, cool. I appreciate it. Thank you. You're welcome.
Okay. Thank you. You too.
Okay, so let's ignore that and let's finish up over here on the board. Okay, so you could commit this to memory if you so chose. I think that's a waste of headspace, okay? Instead, what you can do is you can actually do the conversion, 6.83 centimeter cubed, in a stepwise fashion. What do I mean by that?
Well, I know that, okay, in one meter, there is, oh, I did this, no, I'm in meter speed right now. That's where I'm at. In one meter.
How many centimeters do I have? 100 centimeters, right? Centi means 100. That's a good, easy way to remember it.
So 100 centimeters per meter. Where does this get us? This gets us. So this meter is going to cancel out one of these. And you're going to be left with meters squared and centimeters.
Not quite there, though. We need to do it two more times, right? Because we got two more meters to cancel. So let's do it two more times. That's going to be 100 centimeters per one meter.
And this meter will cancel one of those. And then we're going to have 100 centimeters per one meter last time. And this meter will cancel the final meter. So it's other work.
Yes. For the first part, we put one and three. Why didn't they cancel out the...
and three at the time right because uh basically i'm trying to i'm trying to go in like a stepwise fashion so let's let's let's go back here right if we take uh x cubed divided by x we're left with x squared right same idea for units centimeter cubed divided by centimeter gets us to centimeter squared and here if we start with meter cubed divided by meter what does that get us to meter squared right so this is where we're at when we're doing this one right now and then meter into meter squared gets us what just a meter right and then we do it one last time meter into meter gets us one the unit is successfully cancelled okay so the first the first part of the equation that's just the setup of it this one yeah So, if we look at it, right, because I was saying that, oh, yeah, you know, you could commit this conversion to memory, but why would you when you know your SI prefixes already, and you can just chain them together and not have to worry about memorizing this thing. Following your units is a much easier way to approach problems like this than committing random... Conversion factors to memory. Thank you, Satan. Okay.
So, we are out of, we canceled the meters cubed. We're done with meters cubed. What are we in right now?
Centimeters cubed, right? So, we have centimeter times centimeter times centimeter. This is going to be centimeters cubed.
And I'm going to be a little bit lazy. Actually, not really all that lazy. I'm just going to leave this in scientific notation.
Keep in mind. that this is 10 to the 2. That's what that value is there. This is 10 to the 2. This is 10 to the 2. So, what's 10 to the 2 times 10 to the 2 times 10 to the 2?
Another 6. You just add up your exponents. Very good. Add up your exponents.
You end up with 10 to the 6 centimeters cubed. All right? So, be very careful because when you do a problem like this, hint, hint, hint.
You're not just going to do this conversion once. You need to do it three times to make sure you fully get all three meters out of there. Okay?
But are we done yet? Not quite. We're not in the unit that we're after. We're still looking for milliliters. Right?
Okay. What's my conversion factor here? All right.
Exactly. One cc is one milliliter, so we just finish it off real quick. Not all that much left to do.
Cubic centimeter is times one milliliter, one cubic centimeter. Ccs cancel out, leaving us with 6.83 times 10 to the 6 milliliters. Okay. What about if I give you, so yeah, basically the main idea is that units like this, when you multiply them or divide them, if you multiply them together, they become more powerful. They get bigger in power.
And if you divide them, like what we're doing here, they lower in power. Okay. But what about addition and subtraction?
So, this was one that I didn't notice a couple times, and that's okay. We're here to learn. What if I gave you the expression 5x plus 2x?
What is this? 7x, right? 7x.
And if I gave you the expression 3y? minus negative 2y, this is 5y. Good.
All right. What if I gave you the expression 5x plus 3y? Can't. Just can't because x and y are two different things. I can't factor them out because they're two different variables.
They may not be the same thing. Turns out... Same idea also holds when we're working with units.
So if I give you 5 centimeters plus 2 centimeters, what's my answer? 7 centimeters, right? Keep in mind that this is centimeters to the first power. They don't get more powerful like they do with multiplication.
The power stays the same. It's like you're kind of factoring these things out. Mathematically speaking, it would be 5 plus 2 centimeters. Same thing with subtraction. If there were, I don't know, 17.2 milliliters minus 6.1 milliliters, what's my answer here?
11.1, I think. 11.1 Milliliters. So again, addition and subtraction doesn't cancel out your units. It just more like it factors them. So it's more like 17.2 minus 6.1 milliliters.
Okay. Questions on the units here. Last but certainly not least, occasionally, actually probably pretty frequently going into the future. you will run into units where you kind of start to mix and match things, and that's okay.
So density is a physical property, and it's just the amount, the mass of something divided by its volume, right? So if we do this, mass is usually in grams. Volume is, I don't know, milliliters is pretty good.
Grams per milliliter. Will these units cancel out? Nah. So your units for something like density is going to be grams per milliliter.
All right. There eventually will build up to some kind of crazy guys. Specifically, there's one number that will run into the future in the future.
I think it's like 0.8. I can't remember. 8, 3, 1, 4. And then this will be liter atmosphere Kelvin.
No, no, no. per Kelvin mole, per Kelvin mole. All this thing has four units stuck inside of it. They don't cancel out. And really their only purpose, this is known as the ideal gas constant. If I got it right, I kind of can't remember it for right now.
But the main idea is that these units are all here in this one variable to cancel out other units that are in that equation. We'll talk about it later, but just know. that you're not always going to get nice clean, you know, milliliter or gram units.
Sometimes you'll end up with mixtures of units. Questions on that? All right, so cool.
Race the board and then I think we'll jump into chapter two. Sounds like a good idea to me. I'm not appreciating how much of a fool that guy made me look.
Slightly better. Okay, cool. So we're done. We have our screen back. Okay, so chapter two.
Here we go. And we're going to be talking. I don't actually think that this chapter is called early atomic theory.
But we're certainly going to be getting toward that topic. And don't pay no attention to the man behind the pen. I want the pen.
Give me my pen. I'm not going to want the pen. Oh, because I need it. I need it.
I need it. this or that and i don't even know what week it is anymore okay so um formation of the elements is where we're going to start for today and uh turns out that elements have not always been around um rather most of the elements that we uh we know about today were generated during uh what is known as the big bang aka the start of the university right um main idea is that pretty much lots of energy and lots of matter were confined in a very, very, very small space. And basically, for whatever reason, we don't quite know why yet, at least I don't.
At some point, all of this energy and all of this matter just kind of decided to disperse itself in a fantastic explosion throughout the known universe. And main idea is that very quickly, so very shortly after this expansion occurred, we get the formation of fundamental particles, so things like strings and forks. and all the other fun ones that the news likes to say. Shortly after that, we get the formation of protons and neutrons. These will be important to us shortly.
Then, as time goes on, this time I don't really know, but eventually we get gases, big gas clouds of hydrogen and helium. They gather, they form stars, and basically these stars fuse larger elements. What do I mean by that?
So main idea is that, and we'll talk about this in a bit, but a hydrogen atom, hydrogen atom, is pretty much what is known as one proton. And that is to say it's a particle with a positive, positive electric charge. And the main idea, what stars do, is they take a couple of these hydrogen atoms, so atoms now, and they basically fuse them together.
So here, now we have two protons together. We'll talk about the namings in a bit. when you have two protons together, two protons together, you get a helium atom.
Now, this is a bit strange because, well, what do you guys know about electric charges? Why might this process seem a little odd? Yeah? I'll pay for scissors.
Okay, I saw you first, gentlemen. I mean, generally, like... Exactly, right?
I don't know if you guys are taking visits quite yet, but the main idea is that if you try to put a positive charge next to a positive charge, usually... They repel each other. They don't like being close to each other. Same thing with a negative charge and a negative charge.
They will tend to repel. It's kind of like with magnets. If you try to get the same polarity, a north pole to a north pole, they're going to repel each other. South pole to a south pole, they're going to repel.
North and south, though, they are okay being next to each other. Same with electric charges. Positive and negative also like to be together.
So, if we need to... smash to get two of these positive charges together to make a new atom, that pretty much means that we need to give it a lot, lots of pressure and energy. In other words, we need to pump in a lot of energy and a lot of pressure into this process to get...
these two things not only together, but also stuck together to make our new atom. And this is basically the process that happens in stars, including our own sun. They are essentially element-making factories that go and take smaller particles, a hydrogen and a hydrogen, and make bigger ones such as helium.
And then you can take two heliums to make a boron. Boron? No. lithium beryllium to make a beryllium, or you can give it another hydrogen to make a bora, uh, to make a lithium, so on and so forth. But the main idea, you take smaller ones in a star, give them a crap load of energy and heat, and you make bigger atoms from there.
Okay? So, um, now we're gonna jump into what is known as Dalton's atomic theory. Uh, one thing to note, do I have a date on here?
No, I do not. Keep in mind that Dalton is, he was one of the old school chemists. I think he was around somewhere in the 1800s. I'd have to double check that.
So his understanding of the universe and chemistry was a little rudimentary. He wasn't totally wrong, but he also wasn't totally right about some things either. I'll get there when I get there.
For now, though, he was looking at a bunch of... different materials and he came up with a couple different rules. The first one is that each element is made up of tiny individual particles known as atoms.
So in other words, you can take a fraction of this and chop it, chop it, chop it, chop it, chop it, chop it, chop it, chop it. Eventually, you will end up with a small indivisible, I guess I should have made that yellow, huh? Indivisible particle known as an atom if you chop it up enough. And this one will be a sulfur.
Atom that you that is the smallest in the visible part of same thing here So you can chop chop chop and then you'll end up with a carbon atom carbon atom and Bismuth will also do something similar so that you end up with a bismuth atom. All right Atoms cannot be created or destroyed this suits us for the most part, at least for the intents and purposes of this class. But keep in mind that what I just said, if you give a couple of atoms enough pressure and enough heat, like if you stick them in a star, they will lose their previous identities and create an atom with a new identity to it.
So again, this was before Dalton really knew what was going on, and that's okay, we forgive him for it. He also didn't really know about the process of nuclear fission and nuclear fusion, those things necessary for nuclear armaments. So yeah, he thought that these things were immutable and could not be changed. It turns out if you give them the right conditions, they can be.
All right. All atoms of one element are identical. So what does this mean? He's trying to say here that all... sulfur atoms are the same and all carbons are the same.
Same thing with business, same thing with everything in the periodic table. If it's an element, each atom is going to be the same. This one also is old. So I'm going to circle this guy here. not you go away this is an old point mostly true until we talk about until we talk about isotopes so this is mostly true for the most part there are one or two instances where it's not but They don't have an effect on the element itself that we'll talk about.
All right. Atoms of one element are different from atoms of other elements. This one is, this one's a good one. This one's good.
No argument there, not even in today's present age. An atom of oxygen is going to be different from an atom of uranium, is going to be different from an atom of technetium, rhodium. They're all going to be different. So this one is okay.
and then atoms of one element combine with atoms of other elements to form chemical compounds. So in other words, you can take carbon and combine it with atoms of oxygen, and you can make molecules of other compounds. That one is also okay. Questions?
All right, so next that brings us to what is known as the law of multiple proportions. And really, all this is trying to say It's a little bit word sally, I'll admit. But whenever you take two elements, let's say A and B, they're going to combine in some whole number ratio. So for instance, if we end up with the compound A and B, or AB, this just means that we have one A atom to one B atom. And all ABs are going to be...
are going to have one A atom to one B atom. That's all it means, all right? Next, so in other words, we can also combine it in such a way that AB2, this means that we have one A atom to two B atoms.
and all AB2s are going to behave the same way. One example of this is actually coming up. So, in other words, an example of AB here could be the molecule carbon monoxide, CO gas. This is one carbon atom and one oxygen atom. Meanwhile, we can also consider the molecule CO2, carbon dioxide, and this is going to be one carbon.
atom to two oxygen atoms. That's all we really mean. Excuse me.
That's all we really mean is that these things are going to combine in whole number ratios. One to two, one to three, one to four, two to three, two to four. Well, that's the same thing as one to two, but you get what I mean, right? Questions?
Okay. Let's not worry about the other one quite yet, that second half. Yeah, it's carbon monoxide, carbon dioxide, 1 to 1 ratio versus 1 to 2 ratio, right? So let's think about this in terms of masses, right?
So what do I mean by that? Let's say we have a sample of carbon monoxide, CO gas. And in this sample, we have 12 grams of carbon and 16 grams of oxygen, right?
So in other words, we have one carbon atom to one oxygen atom. And then if I'm going to think about it in terms of masses, that's going to be 12 grams of carbon to 16 grams of oxygen. But what if... What if I then made a new molecule where I doubled the amount of oxygen? Well, if we're going to think about this scenario, right, if we're going to take this idea and double the oxygen, double oxygen, well, let me ask you, what happens to my mass of carbon?
Does it change? Nah. my mass of carbon doesn't change. I'm not touching carbon, all right?
So it's still going to be 12 grams of carbon. But if I'm doubling the number of oxygen atoms, what do you think is going to happen to the mass of oxygen? Also doubled, right?
So what would you expect to see for the mass of oxygen now? 32 grams of oxygen. Why?
Because now we're going from one carbon atom to two. oxygen atoms. So in other words, this is sort of our weird little one-to-one ratio, and if we change it from one-to-one to one-to-two, we see a reflection of that in our masses. This isn't really one to worry about too much. I care more that you realize these are in whole number ratios.
We can worry about calculating the masses of these things later on. But just know that these ratios are reflected. in the mass as well. Okay? Okay.
So, right, and here we go. This is basically a more visual representation of the world according to Dalton. Yeah, we're just going to keep pressing on here.
Oh, that's fancy. Okay, so let's actually talk about atoms themselves. And the main idea is that, okay, atoms are... Well, I know that in this picture here, we're kind of showing atoms as these hard, imalueable, imalueable, I don't know how to spell imalueable, was there two l's?
I don't remember. Imalueable sphere. And actually this isn't the best representation. Truthfully, an atom has a very, very, very, very small core. This is known as the nucleus.
Nucleus. And this is surrounded by a sort of cloudy, cloudy shell that is also soft, right? So this thing can expand, it can contract as needed.
But the main idea is that normally when we think of the atom we're kind of thinking out here, although really the only hard part of the atom is the core all the way at the very center known as the nucleus. It's nucleus, not nucleus. Nucleus. And it's also not nuclear weapon.
They're nuclear weapons. It drives me mad. Okay.
So, in other words, right, we have this nucleus right there, and here's sort of the cloudy, with a chance of meatball, shell. And the main idea is that in the nucleus, nucleus actually has two kinds of particles. The first kind of particle is our proton.
Proton. And these protons have, electrically speaking, a positive one charge. Charge. Charge.
Electric charge. Let me write this better. Positive one. electric charge. There we go.
And we're going to say that that's the red one. The red one is the proton here by convention. We also have these gray ones over here.
These are going to be known as neutrons, N-E-U-T-R-O-N-S. These actually have zero electric charge. They are neutral, hence neutron. Electric.
charge. Okay, that's all well and good. So the nucleus has protons and neutrons, bless you. Protons have plus one electric charge. Neutrons are neutral.
But there is one more fundamental particle for us to talk about, and it's the person, it's the particle that is living out here in the cloudy shell. This one is known as your electron. Electron. And this thing is pretty much the polar opposite of your proton.
It has, whoops, not positive. It carries a negative one electric charge. So, for an atom, well, I guess we'll talk about some of that stuff in a bit. But yeah, these are the three fundamental particles. You have your negatively charged electrons living in this kind of cloudy shell.
You have your positively charged nucleus. Why is it positively charged? It's positively charged because we have protons there. Protons get positive charge. All right?
And then also mixed up with the protons, we have their neighbors, the neutrons. Okay? Some of them may be named Jimmy. I don't know.
But okay. Ideally... For a random atom, if I were to just isolate a particular atom, each atom, unless otherwise stated, should be electrically neutral.
That is to say, my atom should have number of protons equal to number of... electrons. And the main idea here is, well, let's say the main idea is that one positive charge cancels, in a way, or at least, can I spell cancel?
Cancels one negative charge. So if we want these things to be balanced, if we want them to be equal to each other, if we want a neutral atom, number of protons needs to be equal to number of electrons. Keep this in the back of your mind for now as we move forward. Before we start really talking about, you know, some of the specifics in terms of the atom, I do want to at least mention a little bit about... how we got to this particular theory, and it is a theory so far, let's go back in time a bit, right?
Let's really paint the picture here, because one of the first theories of the atom that people thought, oh yeah, this is how atoms work, this is how matter is made up of in the universe, was known as the plum pudding model, still named because whoever came up with this ugly drawing. thought to themselves, oh, this kind of looks a bit like this ugly bread. I have no idea if plum pudding is any good. Never had it.
If you'd like to bring some in and share, I'd be more than happy to try. But the main idea is that... Positive charges, positive charges, where your bread or your pudding, and this is like, this is British pudding, not American pudding.
So British pudding, like it's actually bread. It's weird. Go watch the Great British Bake Off if you don't believe me. But yeah, the positive charge is kind of like your bread. And then.
the negative charges, your electrons, are actually just kind of swimming in your bread, and they're just kind of evenly distributed. Evenly distributed. All right, so this was the first main concept of the atom, one of the more memorable ones at least because of It's food, and food is good. Turns out a guy by the name of Rutherford saw this model, and he was like, okay, all right, let's put this model to the test.
I think he was a fan of Lavoisier, because he certainly liked to put models to the test. And he thought to himself, okay, I'm going to take a thin piece of material, some sort of substance here. Substance.
Don't know really what it is. I think it was a gold foil. Gold foil. And he thought to himself, okay, if plum pudding theory is true, then this gold foil should be more or less just a wall of positive charge. Right?
Because we have an atom and then the red is positive. It's positively charged. So this is positive. positive, positive, and it's only these little plums that are in there that are the negative ones, right?
So, we're not really working in a star, and the main idea is that if he takes a positively charged, positively charged particle, pos-charged-icle, and shoots it at this thin wall of gold foil, well, positive repels positive, it should pretty much just bounce right off of the wall and go backwards, right? Sense? Decent enough.
Theory? What did he see instead, though? Is there a question?
Yeah, okay. Question? Or any, what are your thoughts?
I remember reading about it so when he was shooting at it, like most I think he was saying like most of it of the particles went through it, but only a small amount bounced back. That's exactly what he saw. So this was kind of like what his experiment looked like. Right.
So here's the gold foil that's right there. And this is the positive charge source. And the main idea was that, OK, my positive charge is going to go here.
And in theory, it should hit the gold foil, bounce right. back away. What did he see? Most things, most of the particles that he shot, undeflected. They went right through the gold foil, did not give a damn, right?
This was most of them. And small amounts took a small little detour and very rarely... did these particles bounce back towards him.
What did this suggest? This suggested that instead of having this big orb of positive charge, that instead there's actually only a little teeny tiny positive zone in each one of these atoms. Why did he think this?
Well, most of the particles just kind of went right through. They didn't really care, they just passed right through the gold foil completely undeflected, right? Which kind of suggests that in between these zones here, lots of just empty space. Empty space. Now, every once in a while, one of these particles might accidentally graze one of these hard spheres and get lightly deflected.
which is what we see here, the deflected alpha particles here. And even more rarely, one of them will hit dead on and then get reflected backwards. But basically, majority of the particles that he shot went right through, and only very few of them came back, as would be suggested by the plum pudding.
Which is why he then posited his theory, saying, okay, you know what? Most of these atoms, it's not plum pudding. It's more what we're looking at right here. And for now... keep reading chapter two, make sure you understand the fundamentals of chapter one.
If you haven't already, please be sure to print out the activity sheet for today's activities. I will see you then. Otherwise, be good and stay hydrated.