 Okay, guys. If you don't mind, you could this it up for a second. So I know, and I figured that this would happen, that there is probably a lot of questions and issues about the AL system right now. I actually don't have any office hours today, but Inaz will hopefully be able to be tutoring tomorrow. And that is going to be in HSE 121C. Is that where that's going to be? No, she wants us all in the main tutoring center over there. Okay, so it's going to be continuing education. Yeah, on faculty. The rest of the time I'll be down here. Okay, so the continuing education center. Is there a room number do you know? 100. 100. And you're going to be there for three hours, you think? No. Okay, from 10 to 1. So 10 a.m. to 1 p.m. And that's will be tutoring. Trouble with the AL by doing some stuff. I know that it's kind of finicky putting the right things in. If you guys haven't started yet, I would definitely recommend you start tonight because more than likely you will have a little bit of issues. It shouldn't be taking you 10 hours to do the initial assignment. It should only be taking you a couple of hours for each assignment. Maybe up to five or six for the week. But not too much more than that. Yeah, I think what it's going to come down to is you guys are going to learn the symbols. Learn the executions. And then once you do that, it'll start rolling quite a long time. Are you talking about that? Yeah, so that's the required homework, everybody. That's the required homework is the AL. So where I say recommended homework assignments, that's just recommended. That's just supplemental for your own stuff. And then of course I have extra homework assignments or extra homework sets that I have all the answers written out to. And of course also on top of that I have videos where I show you in detail how to do certain problems. And that's what my office hours are like. My office hours are always in here doing those types of problems. I'm assuming since I've had four office hours and I've had nobody come to office hours that nobody's having trouble with the class. That's the only assumption I can make. Once you guys start coming and telling me, oh, I'm not understanding how to do this problem. I'm not understanding how to do that. Then I'll have more of an idea. But right now I think that everybody's doing well. So if you don't come to me and tell me, I have no other way of knowing. To be using Blackboard, I put all of your assignment due dates. I put the exam dates. I put the quiz dates. Everything up on the calendar in Blackboard. So there's a calendar function. Is anybody not familiar with the calendar function in Blackboard? So everything's set in that calendar function now. So you guys can look at it. I've also put a printout of the calendars on my office door. So if you're not familiar or you don't have a computer with you or something like that, you want to go check. You can just run to my office door and look. So the whole schedule, or at least the schedule for August and September is up there right now because my door isn't big enough for the whole of the schedule. So hopefully everybody has read chapter one by now. If you haven't, then I would suggest you do that. And I think we got to about right here, right? Okay, so if there's no questions before we start in, do we got any questions or comments or anything? Okay, cool. I'll be here for a few minutes after class, too. So if you guys want to come and talk to me, tell me whatever. That would be an appropriate time to do it. Okay, so let's get started today. There's an ascended sheet passing around. Make sure you assign that ascended sheet. Okay, so we were talking about pure substances and molecules. The very last thing we talked about were the differences between pure substances and molecules. So if I have a bottle of water, pure water, like distilled water, that would be a pure substance. Many of the same type of molecule within volume of substance. No mixture of different types of molecules, if you will. So the pure substance, we're talking about the bulk of the solution. Okay, we're talking about the bulk of the material. We're not talking about the individual particles that compromise that bulk, okay? Those individual particles are known as molecules. So those are the smallest portions of the pure substance, okay? So maybe little particles that's a combination of atoms we call a molecule. So here we see oxygen. I don't know if you guys can make that out, but it's two little red balls stuck together, okay? And we call that O2. So that's a molecule, okay? That's a molecule. The next substance we have here is carbon monoxide. Its chemical formula is, well, there's a red ball stuck to a black ball. C is the black ball. O is the red ball, okay? This is also a molecule, okay? And then we'll look at the other one, carbon dioxide, two red balls stuck to a black ball, CO2, okay? This is also a molecule, okay? Now we can say, well, there's a difference between this, this, this one, and these two, right? This one's composed of two of the same types of atoms, okay? Two oxygen atoms, no other types of atoms. The only classification we can say with this, this is a molecule. Here, notice, we've got two different atoms in combination with each other. We said it's a molecule, yes, and it is, because it's the smallest particle of a pure substance, but we also call this the compound, okay? Because it's composed of at least two different atoms. So not only is this a molecule, it's a compound, okay? Think about this, guys. Do you think this is going to be a compound as well? Yeah, why is that? It's got at least two different types of atoms, okay? So it's going to be called a compound. So it's both a molecule and a compound. All of these are particles as well, okay? Individual particles. Helium, for example, helium doesn't bond with anything. Okay? So we can't really call it a molecule because it's not a combination of different atoms bonded together, okay? Or separate atoms bonded together. We'll just call this an atom or a particle, just like we could call all of these particles, okay? So there's a difference between the types of substances you could find in nature. Okay, so let's talk about the atomic theory really quick. So this guy's name is Dalton. He came up with the atomic theory. He was actually just kind of a high school chemistry teacher, ironically enough. But he was very learned in reading the current chemical literature of design. So he took all of these papers that he was reading and realized that he could put them together and come up with an entire theory of how atoms, compounds, and stuff worked, okay? So what he postulated was that all matter consists of atoms. And in fact, he came up with this quite some time ago, a couple hundred years ago. And most of the postulates still hold true today, okay? So it's quite a groundbreaking piece of work, if you will. Okay, so all matter consists of atoms. A particular element are identical in mass and other properties and are different from atoms of any other element. So what does that mean? So if I have a helium atom to another helium atom, okay? What does that mean? That means that those two atoms are exactly the same, okay? For each of them. And they're identical in all other properties. They'll all make my voice very high if I suck them in, okay? Same kind of thing. But if I compare it to neon, it's going to be different than all of the time. We'll go into little details about when it does hold true, but for the most part it does. So for all of these things, for right now I want you to do just little details that might be a little different now. Okay, so something we just talked about, compounds result from the chemical combination of a specific ratio of atoms of different elements, okay? So what does that mean? The specific ratio, we have to have atoms of different elements. Would be considered a compound then? Oh, right, why not? CO2, those are compounds because they're composed of two different types of atoms. And what does the rest of this mean? The combination of a specific ratio of atoms, okay? So what that means is every compound, or every particle of carbon monoxide you find is going to be composed of one to one ratio of C to O, okay? That's what that's saying, okay? Just like when we look at CO2, this is a different compound than carbon monoxide. Of course, you might know this, people get poisoned by carbon monoxide quite readily and then they keel over, carbon dioxide won't poison you, okay? So they have different chemical properties, different physical properties. This compound is always going to be a one to two ratio, okay? So that's what that's talking about. Does everybody understand that? So it's kind of convoluted terms, but it's really not something that's ground breaking or what, okay? So, and again, different elements. So every molecule of a particular compound always contains the same number and same type of atoms as any other molecule of that compound. Again, if I grab one CO molecule with one hand and one CO molecule with the other hand, I look at them and I compare them, they will look and behave identically. That's what this is saying, okay? Does that make sense to everybody? Okay, cool. The last postulate is that atoms can be rearranged, separated, combined, but cannot be created, destroyed, or converted into atoms of any other element. There's a little bit of falsehood in this statement, but not very much, okay? Essentially, you can believe this wholeheartedly unless you're doing nuclear reactions, okay? So I was going to, you know, look at what's happening in the sun or look at what happened when the bomb dropped on Hiroshima or something like that. That would be kind of not going along with this postulate, but those are very, very specific situations, okay? For the most part, if you're not talking about nuclear reactions, this is always true, okay? And we know that, right? So atoms can be rearranged, separated, combined, but cannot be created, destroyed, or converted into other atoms. So what you'll find is it's easier to balance this other equation. H2O, we can take water and electrolysis, break it up into its constituent elements, right? So if we put a charge through this, it'll break it up into hydrogen plus oxygen. Okay, what we want to make sure we do is when we do a chemical reaction, we have to balance that reaction completely, because if we don't do that, we're implying that we've either created or destroyed atoms, okay? So here we've got two hydrogens, right? Here we've got two hydrogens, so that's okay. Here we've got two oxygens, but here we've only got one oxygen. Does everybody see that? So what we need to do is put a two in front of the water altogether, okay? We'll go into balancing equations ad nausea later, okay? I'm just doing this for your own benefit so you can see right now, okay? So you don't have to really focus on this super much, okay? So but now we've got four hydrogen atoms here, right? Does everybody see that? Two times two is four. So we've only got two on this side, so we've got to put a two in front of that H2, okay? So now we say, okay, we've got four hydrogens here, four hydrogens here, two oxygens here, and two oxygens here. So now we can say that matter has neither been created or destroyed through this chemical reaction. It's only been rearranged to make different types of molecules. Does everybody understand that? Okay, cool. So in order to emphasize this rule, you're going to need to be able to balance all of your chemical equations, okay? And again, we'll be learning how to do that in subsequent chapters. Don't harp too much on it right now because I know right now it might be a little difficult for you to do, okay? But we'll do it so much that you guys will be doing it in your sleep. I promise you that, okay? Okay, you'll be not wanting to do it in your sleep because you're doing it so much in your sleep. I'm serious. Okay, so molecules can, of course, be two different types of molecules, only one type of atom or heterotomic molecules, which are molecules made up of different types of atoms. So what is another name for heterotomic molecules? Sounds, yeah, very good. Everybody knows that, right? Everybody knows that. I know it's so early in the morning, but let's try it again. What's another name for heterotomic molecules, guys? Compounds. I understand the difference between homoatomic molecules, which we can just call molecules, okay? Or heterotomic molecules, which we can call compounds. Okay, two atoms we call diatomic molecules. Okay, di means two in atomic molecules. How many do you think those are made up of? Three. Made up of more than one, good job, right? Yeah, made up of more than one because poly means many, okay? So there's different classifications of compounds, molecules, et cetera. So let's try, this is triatomic. Does everybody see that? Those of you who aren't answering, you understand? Okay, because this is very important stuff. It's all very important. I shouldn't have to say that. You can see some more examples of different, so this would be like a polyatomic, polyatomic, polyatomic, diatomic. Okay, so it's not about matter a little bit now. Let's classify matter about the individual particles anymore. Let's look at the bulk of the matter now, okay? So what we can see with our eyes, not just has volume and has mass, is matter. And homogenous matter, some people like to say that. Homogenous substance would be like a mixture of substances. Okay, so like the coffee drink that I see right now, or salt water, a lot of them. Air is heterogeneous matter. It's homogenous matter. So you can imagine if you had heterogeneous matter, you can take the two pieces, two or more pieces, and physically separate them out to make each of them be a pure substance. So how would I do that? Say I had salt water. How could I... Water, does everybody agree with me that salt water is heterogeneous matter, right? It's got salt and water in it. Those two components. To boil it, and what would that do? Evaporate the water and leave the salt, right? I could collect that water, and then I would have the two substances physically separated. Does that make sense? So I took them from being heterogeneous matter to having two bulk of homogenous matter. Does that make sense? Does that make sense? Okay, cool. So, it's matter. And pure substances are very, very similar, okay? Solutions, homogenous matter, we're just going to think of it as pure substances, okay? And then pure substances can be separated into compounds and elements, okay? Pure substances can then be separated into compounds and elements. Of course, we've got elements here, compounds here. A pure substance is a substance that has only one component. A pure substance is a combination of two or more pure substances in which each retains its own identity, not undergoing a chemical reaction. A pure substance can be either an element or a compound. An element is a pure substance that cannot be changed in the simpler form of matter by any chemical reaction, right? So, you've got a copper atom. You can't change that into a gold atom, okay? You can't change that into a hydrogen atom. You've got a compound though. You could potentially change that into simpler substances by breaking it apart and taking it into a test, okay? We could also have a mixture, a heterogeneous mixture, which would be non-uniform composition, random placement, okay? So, that would be like if we had sand and metal filings. It would be non-uniform mixture. We could pick things out, okay? Pick them out. The mixture is really up here. I should have brought something. But you can imagine. A homogenous mixture, on the other hand, would be like a solution, okay? Like a salt water solution. Where we can't pick the salt out and the water out unless we physically separate them by doing some sort of physical separation means like distillation or something like that. So, every piece of that bulk solution will have the same concentrations of different molecules no matter how big of a piece you take out, okay? So, like a heterogeneous mixture. Let's see if I can come up with something. Right? Okay, I got... Do you think if I go ahead, probably not, okay? It would be if I took out something and it would be the exact same thing every time, okay? Does that make sense? Does that make sense to do it? Pass this around. Do you guys understand this stuff? It would be like the salt water or the Coke. All those things. And here's some more examples, of course. This is what? A homogenous or heterogeneous? This thing here. Heterogeneous, right? One is a pure substance, right? It's only water. Notice here, this is a salt water solution. This is a homogenous mixture, okay? Every drink I take will taste just as salty as the last drink. Oh, there's only one molecule. One type of molecule. So, you can call it a compound or a pure substance would be the better way of saying it right now, okay? Pure substance. Look here, we've got two different substances. So, this is a mixture of stuff, right? This is a solution, actually. This is like vodka, actually, because this is ethanol and water, which are the components of vodka. Okay, so this would be like a shot of vodka or something like that. So, would that be a homogenous or heterogeneous mixture? Homogenous mixture, right? If not, what, be selling much vodka, right? Because like the last drink might not have as much alcohol as the first drink, okay? So, this is a mixture, a homogenous mixture. What about this granite rock here? You see, and you can't really see, but there's like black streaks here, red streaks here, white streaks there. Is this a mixture or pure substance? It's a mixture, it's a mixture, it's a solid mixture. Is it a homogenous mixture? Not, because if I take this little piece off, I won't have any of this white streaking, right? I might not even have any of that black stuff in it, okay? So, every piece I take off, it's going to be different, just like I was grabbing out of the chalk box, okay? So, we've got a pure substance, mixture, mixture. This is a compound, this is a homogenous mixture, heterogeneous mixture. Does that make sense to everybody? What about these guys? Is this a pure substance, a copper python? Yeah, it looks like it, huh? What about sugar by itself? Sugar, just sugar? You guys probably don't know, sugar is just one type of molecule, okay? So, let's just pretend sugar is one type of molecule, so what would it be? Pure substance, yeah, and a compound, right? Is this a compound here, copper? Uh-uh, what is it? An element, or a series of atoms, you could say, an element might be even the best way to think about it. What about this soft drink over here, this toast? Is that a mixture? Is that a mixture? Is it a heterogeneous mixture? Uh-uh, what type of mixture is it? Homogenous, yeah, you guys are rocking this one, that's awesome. What about this stuff, oil and water, is that a mixture? It is a mixture, it is a mixture, you can mix it up, you know, you can mix it up, but as it is now, right, is it a homogeneous or heterogeneous mixture? Heterogeneous, okay? It is a mixture, I know this top part, then it wouldn't be a mixture, and if we were only looking at this bottom part, it wouldn't be a mixture, okay? But since we're looking at the bulk of the thing, it is a mixture, okay? Okay, so does everybody understand the classifications of manner, or at least tenuous leap at this point? Okay, go back and read, and I'm sure you'll understand it even in more detail, okay? So let's talk about different types of observations, so we can... So in order to deduce principles that the world runs by, very curious, make observations, you know, a number of observations right now. I'm sure you guys are as well, right? Like, who's around? In fact, all of those observations that I just made are known as qualitative observations, okay? Because they don't give a certain number with the observation that I'm making, okay? Just like here, I can say this is red, or this tastes good. So it's described in informal terms, if you will, okay? I'm going to compare that to quantitative observations. Quantitative observations are made with observation and process that observation with numbers, okay? I could say, well, we've got 16 miles to go. Quantitative observation, because we have both a number that I'm using and a unit, the number being 416, the unit being miles. I could also say, well, man, we've got a long way to go, right? That would be a qualitative observation. It would be the same observation, just one of them I'm using informal terms, the other one I'm using very formal terms, okay? In chemistry class, we're going to be using both qualitative and quantitative observations. Any science is to learn more and more and more about the natural world, okay? And with quantitative observations, we can actually start making assumptions and predictions about what's going to happen. We can take those observations and say, oh, well, if we have this other situation, I'll bet you I can predict what's going to happen because I have all these numbers backing me up, okay? Another quantitative observations would be like, I don't know, mass. 225, that would be a number and a unit. Time to go is that that's not a quantitative observation, right? That's a qualitative observation. It's not almost time to go. But as I said, it's 938 quantitative observations because the number would be 938, the unit would be AM or o-clock or whatever you want, okay? Does that make sense to everybody? Okay, cool. So some people may be from a different country and that might be great because hopefully if you are from a different country they use the metric system in that country and you won't have to worry about converting from English to metric to actually have some idea about what's going on. Those of you life are probably so familiar with English units that metric units are very, very foreign to you. Unfortunately for myself and those of you who are like that using the metric system almost exclusively in this class. At the beginning of the class we'll be learning to convert from English to metric through dimensional analysis, okay? Any problems you will be doing will be similar to, okay? So just mostly kind of these conversion factors, okay? Dimensional analysis is what it's called. The English system is not based on any sort of rhyme or decided that an inch was like or something like that and then they just set it down like that. That's an inch. A foot was the length from his wrist to his forearm or to his elbow, okay? So that's a foot. So these are measurements that are based off of very strange things, okay? The metric system, on the other hand, is units that are based relative to each other. One meter will be a power of 10 away from one meter equals 100 centimeters. But if we look at feet to inches, one foot to 12 inches to 0.33 yards, right? So we got one to 10 to 100 to 1,000 next. So it's a much easier conversion system, okay? But, again, at the beginning, if you're very familiar with the English units, it might be strange to start converting into metric. But once you get the hang of it, it really does start going pretty quickly, okay? And it really does help you guys out. So much more. It's like, these weren't very good at math, okay? They couldn't do very many good calculations. But the Eastern people, they were very good at math, okay? They could do all these crazy calculations. And why is that? So the numbers that we use today, we'll go one, two, three, four, those symbols that you're very used to. Could you imagine trying to do higher math with Roman numerals? Has anybody ever seen Roman numerals? You know, like Super Bowl 42 or something like that, right? I don't even know, you know? What is that, XX211 or something? You know, I don't even know. VX, well, I don't know, right? You can imagine it would be very difficult to do calculus or something like that with those types of numbers, okay? So really, you want to think about it that way. If you're not using the real, the best system to figure things out, it'll be very difficult for you guys to make progress in understanding things, just like the Romans had a really hard time understanding things mathematically because they had such a poor numbering system. Once they adopted the Arabic numbering system or the Phoenician numbering system, it really started working out a lot better for them, okay? And they started building stuff a lot easier. And that's what we're going to do here. So we're going to take our English system that has really no good basis of why these measurements are the way they are, and convert our thinking to the metric system which gives us better basis of it, okay? So in the metric system, are going to be quantities without any metric prefixes, okay? This would be like a gram, a meter, or a liter. Let's compare these two things with prefixes. A kilogram, okay? A kilogram, so one gram is 1,000. This is that we have 1,000 grams. Multipliers of that basic unit, okay? So kilo is 1,000 times that basic unit. Centi is 1,100 times that basic unit. Millie is 1,1000 and so on and so forth. Do you guys see these arrows that I have here? Those are the prefixes that I want you guys to memorize and be very, very familiar with, okay? Because, again, we're doing chemistry. We're doing chemistry which deals with things on a very, very, very small scale. So we're not going to be caring about so much about these mega, these very big numbers, okay? We're going to be caring much, much, much more about very, very small numbers, okay? So we need to know these pico-nano-micromilicenti. Kilo, I want you to know because it's so calm. You can see some common metric units, length, volume, mass, temperature, energy, and time. Let's talk about significant figures now. Significant figures are information-bearing digits of a number, okay? So we make a quantitative observation. We got to know which digits are significant, okay? So the significant figures are only found by the measuring device that you use, okay? So all that's going to be the number of graduations, okay? Plus one, and so the number of certain figures, plus one, uncertain. So if we see this, can you guys see this ruler kind of thing here? I know it's a little small. But we see that our length is right there, that red line, okay? That red line is what we're measuring. Well, we see that it's somewhere in between, what? Five and six there, you guys see that? So what we say, well, that red line is five centimeters long. Will we say that? No. No, will we say it was six centimeters long? No, we wouldn't say that either. We'd probably say it's about five and a half, right? Five point five, or in this example I think they use five point four. So what are we doing with that last digit? We're estimating it, right? We're estimating it because we don't know, we know it's in between there, but we can't really estimate it to any more precision than that. Does that make sense? Okay. So what we find is we know for certain that the first digit is correct. We know for certain it's five something, right? So that's the certain digit. And then whenever we do a measurement, we're always going to have just one more digit and that's going to be the digit that we're kind of sure of, but uncertain, okay? So when we're talking about significant figures, we're talking about all the certain digits plus one uncertain digit, okay? So here we see we've got these graduations that just go one, two, three, four, five, six. So we can only be certain that the first number, which is five, and then we have to estimate the other one giving us two significant figures. Let's look at this ruler now, the same red line, but notice we have what more demarcations, more graduations in that ruler, okay? Because we've got more graduations, we can estimate that number to a more certain figure, okay? More significant digits, okay? So in this case, we can say for certain that we've, well, now we know it goes five point one, two, three. Okay, so now we know for certain five and three are certain digits. Now we've got to estimate that last digit, which now I think they say five point three, six, okay? So that's a more precise number than the five point four. Why is that? Because our measuring device had more graduations on it, okay? But here, how many certain digits do we have now? Two, how many uncertain? One. So how many significant figures do we have? Three. Three, okay? Does everybody get that? So for the first one, we had one certain, one uncertain, two significant. The second one, two certain, one uncertain, three significant. Okay, this happens with every measuring device, even if it's a digital readout, right? Like I go on the scale, or I put this on the balance, right? And it says three, four, two, and three are certain digits. But there's four, I don't know, maybe you've seen this before when you put something on a balance. That last digit kind of fluctuates sometimes. Okay, that's because it's not really sure of what it is, okay? So it happens with every measuring device you use, okay? So in this case, how many significant figures would we have? Three. Three. How many certain digits would we have? Two. And how many uncertain? One. One, always, okay? Always going to be one uncertain digit at the end. Does that make sense to everybody? Okay, good. Before we go, let's just go through the zero rules for the significant digits. So all non-zero digits are significant. Remember, this is a measurement. So here we've got three certain, one uncertain, but four significant, okay? Here we also have four significant because there's four non-zero numbers, okay? Captive zeros, those are zeros located in between non-zero digits. So as we have here in this number, 60.052, captive zeros are significant, okay? So this number has five significant digits, four certain digits, one uncertain digit. Trailing zeros are significant if they're after the decimal point. So if the zero is after the decimal point, then it's significant. Trailing zeros are insignificant if they're not, don't contain a decimal point in that number. Like here, this number of 100 without a decimal point only has one digit, okay? This would be like, because if we were measuring something, 200 and zero, and our measurement was like this, okay? So we could only do that estimation as a 100, okay? Does that make sense? Look here, and the difference, here we've got that decimal point there. That makes those zeros significant, okay? Okay, so in that second number we've got three significant digits. In that first number we have one, and any zeros to the left of a non-zero number are insignificant, okay? So go over these zero rules. You can do these questions here on your own, okay? Make sure you send in that quiz one by today, okay? By five o'clock if you haven't sent it to me. And our intro, math and survey are due next Monday, okay? The end of the day next Monday, so make sure you guys get all that done. If you're having trouble, and Ed is having office hours or tutoring hours from ten to one on Saturday, okay guys? Thank you.