Periodic table trends
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Voiceover: What I want to do in this video is discuss what it means to be a metal, or metallic in nature. First, let's just think about the metals that we encounter in everyday life, or based on our experience the things that we associate with being a metal. The elements that really jump out at us as metals or we always refer to, "Hey, that's a metal, "or that's metallic," are things like iron, or nickel, or copper, or silver, or gold, or aluminum, or at least for me, these are the ones that immediately pop out. I've seen these things before, and they all feel like metals to me, but also think about what's true about these things and as we'll see many other elements on the periodic table that give them this metallic nature. What do we associate with having a metallic nature? One is that these things can be shiny. These things tend to be shiny. There's kind of a gloss when light shines on it. They're not just kind of a matte color. They look metallic literally. That's sometimes a word that's used for it. It has a metallic shininess to it. Another thing that we associate with it is that they tend to be fairly dense. If I take a metal, a block of a metal and if I drop it into water, I imagine that sinking, not floating on top of the water. We also imagine them having a very high melting point, that they tend to be solid at room temperature. Solid at room temperature. As we'll see, this is true of all metals except for one of them which is mercury which is shiny but at room temperature as you might be familiar is in its liquid form. Now the other things that I associate with a metal is that I can make things out of them. I can bend them and shape them in different ways. I think of aluminum foil. I can bend it. It's not just going to crack. I can bend it and put it into different shapes. Even things like iron it might take a lot of pressure to do it, but they're bendable, they're malleable, and definitely things like gold and silver and copper you can actually mold into different types of jewelry. If you put pressure on it, it's more likely to bend than crack and just kind of shear off. So let's put malleability. They're malleable. The other thing I associate with metals is that they conduct electricity well. Conduct electricity. A place that you'll see metal in your life is if you open up your electronics you'll see wires that might be made out of copper, or you might have components that are made out of other metals like gold, or silver, or whatever else. Given that these are some of the properties that we associate with metals, let's think about what's happening at the atomic level to give these elements these properties. The way I think about it let's just go with copper for a second. Let's just imagine a block of copper at the atomic level. Let's say this is one copper nucleus right over there, and it has its sea of electrons. It has its sea of electrons, or not its sea of electrons. It has all of its electrons in their various orbitals. We'll talk about sea of electrons in a second, but this is kind of its cloud of electrons I should say. So this is electron cloud. The electrons are just jumping around in this cloud. It's really a probability density, or there's kind of a certain probability that could be at any point in that cloud. Let's imagine a big solid piece of copper. You would have a bunch of these. You would have a bunch of these all together, all forming the solid. What allows metals to be malleable, to do things like conduct electricity which is the movement of electrons, is essentially that they're very willing to share electrons with each other. By sharing electrons, so you can imagine this is one copper atom and that's another, let's say they're sharing some electrons, that's what allows the electricity or this flow of electrons to happen. If these electrons are loosely bound, then if you put a potential difference of voltage, let's say that you put a potential difference so that this side is more negative, and then this side is more positive, then the electrons are going to want to get away from the negative charge, and move towards the positive charge. If they're relatively freely bound, they can kind of move from one cloud to the next. You kind of end up having what's often called a sea of electrons. Let me write that down. You have a sea of electrons which would make this conductive and that's why you see so much wire made out of copper. The sea of electrons is also what makes it malleable. If someone on this side were to put a lot of pressure this way, and on that side put a lot of pressure that way, things that are rigid would just kind of crack and break, right, would just break right over there, but because you have the sea of electrons it allows it to be malleable. This part might just bend down a little bit, that part might bend up, but they're not going to, the metallic bond is not going to break. Given that this metallic nature really comes from the willingness of these atoms to share electrons with each other, to create the sea of electrons, I encourage you to pause this video and think about which atoms on the periodic table, or which elements are more likely to do that, to share electrons with others and with each other. Really, this is the same principle that we thought about ionization energy, and electronegativity. So pause the video. I'm assuming you've had a go at it. So which elements are most likely to share electrons? We've already seen that if we're on the left side of the periodic table of elements, Group One for example, they only have one valence electron. It would be very hard for them to get enough electrons to complete that outer shell. If they get rid of that one valence electron, they can go to a more stable state. They really want to give away electrons, and the ones over here, they're so close if we talk about the halogens, they're one electron away from completing their outer shell. They're greedy. They want to hog these electrons. They tend to be electronegative. The noble gases, they're done. They definitely don't want to share electrons with anyone. They're kind of in a very stable state. Now, the other thing that we've talked about is as we go down a group, our atoms are getting larger, and larger, and larger. So the outermost, that 55th electron in cesium is much more loosely bound because it's further away than say the third electron in lithium. So just as we saw as the elements in this bottom left have a very low ionization energy. It doesn't take much energy to remove an electron from them, these are the ones that are most likely to share electrons, and these actually have the highest metallic nature. So high metallic, high metallic nature. The ones on the top right, these are going to be the opposite. They're very unlikely to share electrons. They're very electronegative. They have a very high ionization energy. They have a low metallic nature. I could imagine some things are popping into your brain at this point. We started thinking of the elements that in our everyday life we associate with metals, but what I'm saying is that these things over have an even higher metallic nature, but what about something like calcium. Every day what I imagined when I typically, or when a lot of people imagine calcium, they think of kind of a chalky, a white chalky substance, very rigid, not very malleable, not very good, not very shiny, not very good at conducting electricity. Based on what I just told you, this would have a higher metallic nature than something like aluminum. What you have to remind yourself is that what you see is not actually pure calcium, that kind of chalky thing. That's calcium carbonate. Pure calcium, actually, this is actually a picture of pure calcium. It is shiny. It does have these metallic properties. The general trend here is that all of these, these are very high in metallic nature, and these are very low metallic nature which also makes you probably realize while most of the periodic table is a metal of some form. If aluminum is a metal, and all of these things have a higher, have a higher metallic nature than all of this stuff, all of this stuff are metals, and that is the case. The S block, the D block, the F block, these are all metals. Then a good chunk of the P block, a good chunk of the P block are considered metals, and then these are kind of sometimes referred to as metalloids, Only this section of the periodic table is not considered a metal. That makes sense. Nobel gases, they are gases. They don't, they're not very reactive. they don't bond so they don't form kind of a structure that can even do this type of thing. These other ones over here even carbon when it is formed a lattice, it does not conduct electricity well. It tends to not be so malleable if you think about something like a diamond, or if you think about, well, a diamond might be the best example of that. Anyway, hopefully this gives you a sense of metallic nature and the trends in the periodic table. High metallic nature, and as you go to the top right, lower and lower metallic nature.