 We are all here because of chemical energy, and I said chemical energy is potential energy stored in chemical bonds. To start this conversation, I'm gonna throw some units at you that are used to measure chemical energy in food. So I'm gonna throw a unit at you just like molarity is a unit of concentration and meters are a unit of distance. This thing is a unit of energy. It's a measure of energy, and it's something that's very very familiar to you. Are you ready? A measure of the amount of chemical energy in food is the calorie and I capitalized it on purpose and I marked the capital. In fact, I'm going to also highlight the capital so that you know that I'm purposefully capitalizing this. This is a nutritional calorie and again, it's a measure of the amount of energy, potential energy stored in chemical bonds in food. I'm gonna give you a definition for a lower case calorie because an uppercase calorie is actually a kilo calorie. But a calorie is the amount of energy required to increase the temperature of one gram of water by one degree Celsius. Okay, one gram of water is a very small amount of water. It's like a little tiny cube of water. If you imagine applying a flame to that little cube of water and you had a little tiny thermometer in there, when the thermometer goes up one degree Celsius, you at that exact moment you put in one calorie of heat from the candle to warm up and really make those water molecules move faster. That's a transfer of energy. We took candle heat and we transferred it to molecule kinetic energy and we measured the amount by the temperature change. A lower case calorie does one tiny gram of water increased by one degree Celsius. A big calorie, which is a nutritional calorie. So this is the kind of calorie that's reported on your food. When you have a nutrition label and you're like, oh, how many calories am I gonna eat? It's actually kilocalories and that's the amount of energy required to increase the temperature of one kilogram of water by one degree Celsius. A kilogram of water, I was like, dude, what is a kilogram of water? It's about two gallon. Wait, two liters or two gallons? It might be two liters. I think it's two liters. And what I'm gonna tell you, I'm very curious. I can't remember the exact number. I know I wrote it down somewhere. Oh, it's about two gallons. No, I wrote, I did write it down. I just saw it in my notes over there. That was very efficient of me. So two milk jugs of water increased by one degree Celsius, that's one... Doesn't a kilocalorie, a nutritional calorie, seem really big? A gummy bear, one gummy bear, contains eight kilocalories. So if you burned up, you captured all the chemical energy inside that one gummy bear, you could heat two gallons of water by eight degrees Celsius, because it had eight calories in it. I understand if that, if you're like, nope, I call bulldokey on that. There's labs that you can do where you actually burn stuff up and measure the temperature of water and try to estimate how many calories are in things. Super interesting, beyond the scope of our class. So you get to trust me that this is, there is a lot of energy in the chemical bonds. How? What? Really how? I'm gonna do a demonstration for you. And what would be most amazing is if you went to grab two magnets, if you pushed pause right now and you went to grab two magnets and had magnets, I will put them on my neck so that you can see them because you can't see them if they're on my dress. There we go. I need like a spot. What? Here are my two magnets. So all that time you go get your own two magnets. If you imagine that these magnets are atoms, remember, chemical bonds are shared electrons. When when atoms share electrons with each other, they form a chemical bond. If you imagine these little guys moving around, they've got kinetic energy and they're representing atoms and they form a chemical bond when they connect. Here they are moving around, moving around, moving around and they form a chemical bond. Now because they connect and I can break that chemical bond by pulling them apart, but they always have kinetic energy, right? And so they're always moving around and they formed another chemical bond. Chemical bonds, where there's my pen, chemical bonds store energy in this way. When chemical bonds break, energy is required. So these are facts that you will memorize. I can never remember them unless I imagine magnets. Chemical, when chemical bonds form, energy is released. Okay, I would almost say that this, these two facts might be the most important facts in today's lecture. If you're going to break chemical bonds, you have to put energy in. And when chemical bonds form, energy is released. Now, depending on the stability of the chemical bond, breaking them might be really easy. Or it might be really hard. These magnets that I have are actually really strong. And I definitely, I'm not a weenie, but I'm telling you, I'm having to, like I'm trying to pull the magnets apart and they're not coming apart. So I'm contracting more there. I got them. I'm contracting my muscles more and more and more. I'm putting more and more energy in to break the bond. It requires energy to break those chemical bonds. But because all the atoms have kinetic energy, they will, if they get close enough to each other, they can reform that chemical bond without me doing anything. And I can actually capture that energy and use it to do work. Here they are doing their thing. If, this is the way I imagine it. I imagine one of them moving. I imagine a piece of paper between them and this magnet can do work on the paper, move the paper a distance without me doing any work at all. I'm not spending any energy. I'm just trying to demonstrate this for you. But this is the energy of the molecule itself. And I could capture that snap, that movement. The magnet moves a distance and I could capture that energy and use it to do work like a water wheel. Captures the energy of water moving and captures that energy and uses it to, I don't know, run a washing machine or whatever. Same thing with chemical energy. I can't visualize any of this unless I accept the magnet that they're like magnets. And I memorize that when chemical bonds break, I have to do work. I have to put energy in. And when they form, energy is released. This is how we're going to get energy out of chemical bonds. And to demonstrate this for us, I have a little visual, a little slideshow talking about the most important energy providing molecule. I always hate saying the, I mean, you can fight me on that. And I probably would fight myself on that as well. But a very important energy providing molecule for biological systems, which is adenosine, triphosphate, or ATP. So let's use ATP as our example of how these chemical bonds forming and breaking actually result in energy that the cell can use to do work.