Hi guys, welcome back to another video. Yesterday we looked at graphite and how graphite is arranged in these sheets. Each carbon atom spawned with three others leaving one electron de-localized and free to move. The electron has a charge, it's got a negative charge and it's moving. Moving charge means electricity. Graphite can conduct electricity extremely well because of these electrons moving in between the sheets of graphene. Today we're looking at diamonds. So diamonds. Diamond is made from carbon atoms. Each carbon atom is covalently bonded to four others in a tetrahedral arrangement. Tetrahedral, it's a new word. It won't be a new word by the end of this topic. Tetrahedral means it's bonded to four others carbon atoms. So tetra in Latin means four. Tetrahedral means four arrangement. So it's a tetrahedral arrangement. This forms a covalent network solid. So diamond is a covalent network. These covalent bonds are extremely strong and require a large amount of energy to break, which gives diamond an extremely high melting point. So these notes pause the video and please write these down in your notebooks for the exams for the inner theatre. So pause the video now and you can write them down. I'll put this video up on Google Classroom Peter Watch, SciShow, Great YouTube Channel. As all of diamonds electrons are involved in bonding, none of them are free to carry a charge. This makes diamond a perfect insulator. No electricity can get passed through it. Many artificial diamonds are used in electronics. Your phone, believe it or not, has tiny little diamonds in it in the illicit circuitry. They're not worth anything because they're so tiny, but they stop electrical charge from going where it doesn't need to go. This is what the arrangement of a diamond looks like. Each of these starts a carbon atoms and as you can see they're bonded to four others. This is a very small close-up view. These ones at the end you wanted to form more in arrangements billions of atoms wide. So they bonded to four others, all the electrons are involved in bonding, meaning none of them are free to carry a charge. These are also notes that you can run in your book. This is background information. You don't really need to know this, but just Ella tropes, you word. Ella tropes are the different physical form of which an element can exist. So graphite, charcoal and diamond are all Ella tropes of carbon. These are all made of nothing but carbon, but they're just arranged slightly differently to give them different properties in different forms. Another Ella tropes of carbon is called Buckman's the Philorine, also known as Buckyballs. This is C60. Each molecule has 60 carbon atoms arranged in a soccer ball-like shape. This was discovered about 10 years ago and has some very cool properties. Extremely strong. Ella tropes of carbon, you got graphite here, you got diamond here, diamond and you got some... Unless you've got this, it's been a while since I've made these slides, but some other form of carbon there. So we look at the melting points, extremely high melting points, because they're made of strong covalent bonds. It takes a lot of energy in the form of heat to break. Conductivity, turns electricity, diamonds and insulator, well graphites a conductor. And hardness, diamonds, one of the hardest, what it is the hardest known material. And graphite's very soft, it's used in pencils, you can write with it. Silicon dioxide, covalent network. So silicon dioxide is the last covalent network we're looking at. Silicon dioxide consists of silicon and oxygen atoms held together by covalent bonds in a tetrahedral arrangement. So it's covalent network solid. This is the last notes for the video to put in your book. So this is a typical exam question. Complete the table below by choosing the appropriate type of solid that matches the properties shown in the table. Let's take a look at this. A, we've got a pretty low melting point, I mean, 290, it's kind of still hot. So medium melting point, medium burning point, conduct electricity. As a solid, it doesn't. As a molten, it does conduct electricity. So you build in water. Yes, and the solution conducts electricity. What this says to me is it tells me we've got a salt and it's an ionic solid. Because ionic solids do not conduct electricity when they're solid because the ions are stuck in place, they cannot move. When the ions are dissolved in solution, the sodium ions and the chloride ions and the potassium ions can all move around in the solution. Their charge particles moving, they can carry a charge. So A is ionic. Let's look at D now. D, 660 melting point, very high boiling point conducts electricity as solid and molten. So being solid and molten conducts electricity, solid will not work. To me, this looks like metallic solid. As a solid metal, conduct electricity like copper wires, but also molten metal can also conduct electricity. These two are very similar and C, the only difference is conduct electricity. C is our covalent network and it's actually diamond in this case. So this question is not written the best because covalent networks can sometimes conduct electricity that graphite can. But if we just go back here, I think this is diamond because very high melting point does not conduct electricity. It's not solid, but in water. So C will be covalent network. And B, lowest melting point, low boiling point is molecular. We haven't seen molecular solids yet, but we will see them next week as the last type of solid we're looking at. Alright, so this will be next week. Sneak preview of the slides. Cool. Thanks guys.