1 00:00:03,240 --> 00:00:06,320 Gold. This is what alchemists dreams were made of. 2 00:00:06,320 --> 00:00:09,760 The medieval thinkers spent their lives trying to find a way 3 00:00:09,760 --> 00:00:13,760 to turn cheap metals, such as this lead, into gold. 4 00:00:16,400 --> 00:00:19,320 Success would bring them fame and infinite fortune, 5 00:00:19,320 --> 00:00:21,720 but is such magic even possible? 6 00:00:21,720 --> 00:00:25,040 Join us in the search for the philosopher's stone. 7 00:00:46,480 --> 00:00:48,480 APPLAUSE 8 00:01:02,560 --> 00:01:05,680 The alchemists were obsessed with the idea of producing 9 00:01:05,680 --> 00:01:07,240 a philosopher's stone. 10 00:01:07,240 --> 00:01:12,040 A magical rock or powder that could turn metals into gold. 11 00:01:12,040 --> 00:01:15,960 There are even stories of espionage, kidnap and even murder 12 00:01:15,960 --> 00:01:18,720 in a bid to steal the secret of the stone. 13 00:01:18,720 --> 00:01:21,000 But what about the gold I just made? 14 00:01:23,240 --> 00:01:25,720 Well, I'm afraid we cheated. 15 00:01:25,720 --> 00:01:28,560 I'm not an alchemist. My name is Dr Peter Wothers 16 00:01:28,560 --> 00:01:32,080 and I'm a chemist from the University of Cambridge. 17 00:01:32,080 --> 00:01:33,600 I did start with lead. 18 00:01:33,600 --> 00:01:37,080 It was a specially prepared form of lead that reacts 19 00:01:37,080 --> 00:01:41,760 with the oxygen from the air to give this beautiful lead oxide. 20 00:01:41,760 --> 00:01:44,440 This yellowy orange compound here. 21 00:01:44,440 --> 00:01:46,760 So we did cheat here. 22 00:01:46,760 --> 00:01:49,080 And my philosopher's stone, well, 23 00:01:49,080 --> 00:01:53,560 it was just a hot coal which started this reaction. 24 00:01:53,560 --> 00:01:57,160 Some alchemists used this reaction to try to convince people 25 00:01:57,160 --> 00:02:01,280 that they could make gold. But is such a feat even possible? 26 00:02:01,280 --> 00:02:04,520 In the last of this year's Royal Institution Christmas lectures, 27 00:02:04,520 --> 00:02:06,080 I hope to find out. 28 00:02:06,080 --> 00:02:07,760 In the previous lectures, 29 00:02:07,760 --> 00:02:10,800 we've looked at the elements in the air, and water, and now we are 30 00:02:10,800 --> 00:02:14,440 going to look at the elements in the earth and how we can extract them. 31 00:02:14,440 --> 00:02:18,120 How we can use them and whether we can turn one into another. 32 00:02:18,120 --> 00:02:21,480 To help me, I have a giant periodic table made up 33 00:02:21,480 --> 00:02:25,600 of members from the audience here at the Royal Institution. 34 00:02:25,600 --> 00:02:28,880 Let's just look at the elements we have already talked about. 35 00:02:28,880 --> 00:02:31,520 We have lead, can you stand up, please, lead? Thank you. 36 00:02:31,520 --> 00:02:33,080 We were looking at you 37 00:02:33,080 --> 00:02:35,360 and you were reacting with the oxygen from the air. 38 00:02:35,360 --> 00:02:38,080 Can you stand up please, oxygen? OK. 39 00:02:38,080 --> 00:02:42,840 This is how we normally find our metals in the earth. 40 00:02:42,840 --> 00:02:44,880 We don't find them lying around, 41 00:02:44,880 --> 00:02:47,800 they are normally combined with the oxygen from the air. 42 00:02:47,800 --> 00:02:51,680 Or maybe sulphur, or occasionally other metals. Thank you very much. 43 00:02:51,680 --> 00:02:55,280 If we put our periodic tables down now, please. 44 00:02:55,280 --> 00:02:59,560 But occasionally, we can find metals just lying around. 45 00:02:59,560 --> 00:03:03,640 The classic case is gold. Where are you, gold? 46 00:03:03,640 --> 00:03:08,680 You are so special because sometimes you can be found just lying around. 47 00:03:08,680 --> 00:03:14,760 In fact, here's a piece of you here. This is a gold nugget. 48 00:03:14,760 --> 00:03:16,880 Thank you, periodic table, at ease. 49 00:03:16,880 --> 00:03:21,280 This is pure gold. And it can be found like this in nature. 50 00:03:21,280 --> 00:03:24,320 In fact, this is how it is normally found. 51 00:03:24,320 --> 00:03:28,160 Now the remarkable thing about gold is that it doesn't change over time. 52 00:03:28,160 --> 00:03:32,040 So you could leave it for tens, hundreds, even thousands 53 00:03:32,040 --> 00:03:37,120 of years and it'll still have this beautiful appearance. 54 00:03:37,120 --> 00:03:40,360 I've got a very old piece of gold to show you now. 55 00:03:40,360 --> 00:03:44,640 Would you please welcome, from the Museum of London, Meriel Jeater. 56 00:03:44,640 --> 00:03:46,640 APPLAUSE 57 00:03:52,320 --> 00:03:55,600 I gather that this is a piece of local gold, is that right? 58 00:03:55,600 --> 00:03:59,960 Exactly, yes. It was found in London, in Cannon Street in 1976. 59 00:03:59,960 --> 00:04:04,160 It's actually a Roman gold and emerald necklace. That's beautiful. 60 00:04:04,160 --> 00:04:07,400 This is pure gold wire running through these emeralds? 61 00:04:07,400 --> 00:04:10,720 That's right, yes. And you say this is from the early Roman times? 62 00:04:10,720 --> 00:04:14,920 This is how old? Nearly 2,000 years old, yes. 2,000 years old. 63 00:04:14,920 --> 00:04:17,160 Has this been heavily restored? 64 00:04:17,160 --> 00:04:19,800 It's been given a bit of a clean to get the mud off. 65 00:04:19,800 --> 00:04:24,160 Just the mud off and the gold itself was looking just like this? Exactly. 66 00:04:24,160 --> 00:04:26,760 That's why it's so wonderful for archaeologists. Exactly. 67 00:04:26,760 --> 00:04:29,960 For me as a chemist, I think it's incredible that you can find 68 00:04:29,960 --> 00:04:32,200 gold in this state and it doesn't tarnish over time. 69 00:04:32,200 --> 00:04:34,480 It doesn't combine with oxygen or water or anything. 70 00:04:34,480 --> 00:04:35,920 This is how you find it. 71 00:04:35,920 --> 00:04:38,080 You can see that clearly it was highly prized 72 00:04:38,080 --> 00:04:40,680 and I think maybe you should take it back to the museum. 73 00:04:40,680 --> 00:04:43,320 Thank you very much. Pleasure. Big round of applause, please. 74 00:04:43,320 --> 00:04:45,360 APPLAUSE 75 00:04:48,640 --> 00:04:52,440 This has lasted so well because it was so highly prized, 76 00:04:52,440 --> 00:04:56,560 so valued there but also because it didn't change over time. 77 00:04:56,560 --> 00:04:59,600 But, of course, we have a saying about the value of gold. 78 00:04:59,600 --> 00:05:02,680 Sometimes people are told, "You're worth your weight in gold." 79 00:05:02,680 --> 00:05:05,680 Have you ever been told you're worth your weight in gold? Yeah. 80 00:05:05,680 --> 00:05:07,920 Oh, you have! Oh, good. Who told you that? 81 00:05:07,920 --> 00:05:10,360 I can't remember. Probably a parent. 82 00:05:10,360 --> 00:05:14,560 Maybe we should ask gold. Where's gold sitting? Are you gold, yes? 83 00:05:14,560 --> 00:05:18,240 Have you been told that you're worth your weight in gold before? 84 00:05:18,240 --> 00:05:21,000 I think my parents... They've told you this, have they? 85 00:05:21,000 --> 00:05:25,000 I think we should see just how much gold that would be. 86 00:05:25,000 --> 00:05:27,400 Would you like to come down to the front, please? 87 00:05:27,400 --> 00:05:29,840 APPLAUSE 88 00:05:31,080 --> 00:05:32,720 Would you like to face the front here. 89 00:05:32,720 --> 00:05:35,120 Would you like to tell everyone your name? Emma. 90 00:05:35,120 --> 00:05:36,160 Take a seat on here. 91 00:05:36,160 --> 00:05:39,400 If you just carefully sit down on there. That's beautiful, lovely job. 92 00:05:39,400 --> 00:05:41,840 OK, right, are you sitting comfortably? 93 00:05:41,840 --> 00:05:45,520 Yep. Then we'll begin. This is where I get very excited. 94 00:05:45,520 --> 00:05:52,200 This is all real gold. And it's pretty good stuff, actually. 95 00:05:52,200 --> 00:05:54,800 Have you ever held a big block of gold before? 96 00:05:54,800 --> 00:05:57,080 No. No. Well, have a feel of this. 97 00:05:58,280 --> 00:06:01,440 That is pretty exciting, isn't it? Would you like to feel this as well? 98 00:06:01,440 --> 00:06:03,240 I'm afraid I can't let everybody have... 99 00:06:03,240 --> 00:06:05,160 I know, it's amazing, isn't it? 100 00:06:05,160 --> 00:06:10,480 This is actually about the same as six large bottles of fizzy pop. 101 00:06:10,480 --> 00:06:12,680 I'm just going to put this on here. 102 00:06:14,760 --> 00:06:18,200 OK, I think you need more than that. Let's keep going. 103 00:06:18,200 --> 00:06:21,440 Let's put this one on. It really is pretty good stuff, this. 104 00:06:22,960 --> 00:06:25,880 This is 24ct pure gold. 105 00:06:25,880 --> 00:06:28,120 And this one here. 106 00:06:29,440 --> 00:06:31,400 More. More still. 107 00:06:34,480 --> 00:06:38,520 Not quite. No. OK, let's try this one. 108 00:06:43,800 --> 00:06:46,520 I think it's almost level but not quite. 109 00:06:46,520 --> 00:06:49,320 I think we need just a little bit more. 110 00:06:49,320 --> 00:06:52,400 Has anyone else in the audience got any gold? 111 00:06:52,400 --> 00:06:54,320 LAUGHTER 112 00:06:54,320 --> 00:06:56,600 I found some on the way in. 113 00:06:56,600 --> 00:06:58,440 Oh, you've got some? 114 00:06:58,440 --> 00:07:02,240 Isn't that Nobel prize-winning chemist Prof Sir Harry Kroto? 115 00:07:02,240 --> 00:07:03,760 I think it is. 116 00:07:03,760 --> 00:07:05,800 APPLAUSE 117 00:07:14,040 --> 00:07:17,520 So what exactly...I think I might know what this is. 118 00:07:17,520 --> 00:07:22,400 Is this really your Nobel Prize? Yes, they give them away. 119 00:07:22,400 --> 00:07:27,480 This is solid gold, isn't it? It's solid gold. And I want it back. 120 00:07:27,480 --> 00:07:32,440 Well, of course, Harry. I trust you. Oh, thank you. 121 00:07:32,440 --> 00:07:35,360 Right, anyway, maybe this is just what we need. 122 00:07:35,360 --> 00:07:37,400 Let's just try that on there. 123 00:07:39,040 --> 00:07:42,040 Oh, I think that's pretty well balanced now. 124 00:07:42,040 --> 00:07:43,320 I think that's quite amazing. 125 00:07:43,320 --> 00:07:48,200 I think that is 43kg of gold and one Nobel Prize. 126 00:07:48,200 --> 00:07:50,920 Thank you very much. Big round of applause. 127 00:07:50,920 --> 00:07:52,800 Stay where you are for a moment. 128 00:07:52,800 --> 00:07:55,120 APPLAUSE 129 00:07:55,120 --> 00:07:59,120 Thank you, Prof Kroto, for saving the day. This is quite amazing. 130 00:07:59,120 --> 00:08:02,360 43kg, but it doesn't actually look too much there, does it, Emma? 131 00:08:02,360 --> 00:08:03,840 What do you think? 132 00:08:03,840 --> 00:08:05,840 As you say, it's very dense 133 00:08:05,840 --> 00:08:09,080 and this is why it doesn't actually take up much space. 134 00:08:09,080 --> 00:08:12,800 If you were made of gold, you would weigh 800kg, 135 00:08:12,800 --> 00:08:16,200 which is about as much as a small car. 136 00:08:16,200 --> 00:08:20,040 Which is quite a lot really, isn't it? So that's pretty impressive. 137 00:08:20,040 --> 00:08:23,480 How much do you think this is worth? How much do you think? Have a guess. 138 00:08:23,480 --> 00:08:25,960 Um...quite a lot. 139 00:08:25,960 --> 00:08:28,800 I think you're right there. Quite a lot, yes. 140 00:08:28,800 --> 00:08:31,840 Anyone have any other ideas? Shout it out. Yes? 141 00:08:31,840 --> 00:08:34,680 One million? One million, actually, you're not far off. 142 00:08:34,680 --> 00:08:36,880 It is even more than that. 143 00:08:36,880 --> 00:08:42,440 This is about £1.5 million worth of gold just sitting here. 144 00:08:42,440 --> 00:08:45,680 Which is pretty impressive, isn't it? All right, now. 145 00:08:45,680 --> 00:08:47,720 If you just stay where you are sitting, please. 146 00:08:47,720 --> 00:08:52,160 I need to unload this first of all. I'll just take that and... 147 00:08:52,160 --> 00:08:53,880 LAUGHTER 148 00:08:53,880 --> 00:08:56,840 Just going to put these over here. 149 00:09:00,080 --> 00:09:01,960 A few little bits left. 150 00:09:03,160 --> 00:09:06,760 There we are. That's fantastic. OK, thank you very much, Emma. 151 00:09:06,760 --> 00:09:08,080 Big round of applause. 152 00:09:08,080 --> 00:09:10,000 APPLAUSE 153 00:09:14,960 --> 00:09:19,360 Gold really is an incredibly dense substance. 154 00:09:19,360 --> 00:09:22,440 But actually, it's not the densest element. 155 00:09:22,440 --> 00:09:25,240 Could we just have cards up for a second, please? 156 00:09:25,240 --> 00:09:31,200 That honour goes to osmium. You are the densest thing in the universe. 157 00:09:31,200 --> 00:09:34,160 Well, at least on Earth. Did you know that? 158 00:09:34,160 --> 00:09:36,840 I don't mean that in a bad way. This is just you as an element. 159 00:09:36,840 --> 00:09:39,240 Osmium is incredibly dense indeed. 160 00:09:39,240 --> 00:09:42,600 Can we just keep the cards up for the people in the same row 161 00:09:42,600 --> 00:09:45,360 as osmium and gold. Everyone else down. 162 00:09:45,360 --> 00:09:48,880 Caesium stay up, barium stay up. All the way over to mercury. 163 00:09:48,880 --> 00:09:53,720 Why is it, then, that these elements are so incredibly dense? 164 00:09:53,720 --> 00:09:57,640 The most dense element is osmium, closely followed by iridium. 165 00:09:57,640 --> 00:10:00,920 Well, atoms after osmium, iridium, gold, 166 00:10:00,920 --> 00:10:02,880 all these other ones are getting heavier. 167 00:10:02,880 --> 00:10:04,880 So the atoms themselves are heavier 168 00:10:04,880 --> 00:10:07,880 and yet these ones are the most tightly packed. 169 00:10:07,880 --> 00:10:11,200 So it's not just to do with how heavy the atoms are. 170 00:10:11,200 --> 00:10:14,520 We also need to look at the bonding that we have between them. 171 00:10:14,520 --> 00:10:17,280 And this is what we can see in the graph here. 172 00:10:17,280 --> 00:10:20,520 This shows how much energy we need to put in to separate 173 00:10:20,520 --> 00:10:23,600 a certain number of atoms of these elements. 174 00:10:23,600 --> 00:10:26,840 And we see that we've got a peak around tungsten. 175 00:10:26,840 --> 00:10:29,720 This is why we use tungsten in light bulb filaments, 176 00:10:29,720 --> 00:10:32,080 because it's very difficult to pull them apart. 177 00:10:32,080 --> 00:10:34,000 And we have very high temperatures. 178 00:10:34,000 --> 00:10:38,200 But as we go beyond tungsten, the bonding isn't quite so strong 179 00:10:38,200 --> 00:10:40,440 but the atoms are getting heavier. 180 00:10:40,440 --> 00:10:43,760 And so it's bit of a balance between the strength of the bonds, 181 00:10:43,760 --> 00:10:47,200 how tightly they are packed, and how heavy the atoms are. 182 00:10:47,200 --> 00:10:51,600 This is why we reach a maximum for osmium and iridium. 183 00:10:51,600 --> 00:10:54,880 Gold, platinum and so on are still very dense afterwards, 184 00:10:54,880 --> 00:10:57,920 but the maximum is there for osmium and iridium. 185 00:10:57,920 --> 00:11:01,560 So osmium is even more expensive than gold, in fact. 186 00:11:01,560 --> 00:11:04,560 And if someone was really going to pay you a compliment 187 00:11:04,560 --> 00:11:07,920 they would say, "You are worth your weight in osmium." 188 00:11:07,920 --> 00:11:11,880 Actually, these metals are not the only precious things 189 00:11:11,880 --> 00:11:14,000 we can extract from the earth. 190 00:11:14,000 --> 00:11:18,560 There are even non-metals that we can sometimes find as well. 191 00:11:18,560 --> 00:11:20,760 Hello. Hello, Prof Kroto. 192 00:11:20,760 --> 00:11:25,120 I'm assuming you would like your Nobel Prize, would you? 193 00:11:25,120 --> 00:11:29,400 I'd swap it for those bigger ones. Yes, so would I, I think. 194 00:11:29,400 --> 00:11:32,080 Well, there we go. Thank you very much. 195 00:11:32,080 --> 00:11:36,400 Perhaps you could tell us what you won the Nobel Prize for. 196 00:11:36,400 --> 00:11:40,200 It's for discovering an alternative to these. 197 00:11:40,200 --> 00:11:43,600 This is graphite and this is diamond. These structures. 198 00:11:43,600 --> 00:11:45,640 These are actually the only ones that I knew about 199 00:11:45,640 --> 00:11:47,160 when I was at school. 200 00:11:47,160 --> 00:11:50,040 In the text books, there were just two types of carbon. 201 00:11:50,040 --> 00:11:51,960 Two different forms called allotropes. 202 00:11:51,960 --> 00:11:54,400 One has this arrangement. This one is the graphite. 203 00:11:54,400 --> 00:11:56,640 This is the sort of thing you find in your pencils. 204 00:11:56,640 --> 00:12:00,480 It's pretty soft and well, carbon, it's just an arrangement of carbon. 205 00:12:00,480 --> 00:12:03,040 Diamond looks very different though, doesn't it? 206 00:12:03,040 --> 00:12:06,360 I don't suppose...you've very kindly lent us your gold, 207 00:12:06,360 --> 00:12:09,080 I don't suppose you have a spare diamond on you, do you? 208 00:12:09,080 --> 00:12:12,600 I don't myself but my wife actually has one. 209 00:12:12,600 --> 00:12:16,400 A-ha! You don't want to take that as well, do you? Well, just borrow it. 210 00:12:19,760 --> 00:12:22,600 I hope I get it back. Thank you, Mrs Kroto. Of course, yes. 211 00:12:22,600 --> 00:12:25,360 You can trust me. 212 00:12:25,360 --> 00:12:30,880 This is a beautiful ring here. Is it an engagement ring or something? 213 00:12:30,880 --> 00:12:32,880 It's really quite lovely. 214 00:12:32,880 --> 00:12:35,080 The diamond comes out quite easily, doesn't it? Yes. 215 00:12:35,080 --> 00:12:36,440 LAUGHTER 216 00:12:36,440 --> 00:12:39,560 We can see it more clearly now. Look at that. It's beautiful. 217 00:12:39,560 --> 00:12:42,920 What a beautiful diamond. It is a real diamond though, is it? 218 00:12:42,920 --> 00:12:46,720 It as real as you can get. It's quite stunning. 219 00:12:46,720 --> 00:12:52,680 Of course, we want to show that this graphite is made up of carbon. 220 00:12:52,680 --> 00:12:54,120 There is one way we can do this. 221 00:12:54,120 --> 00:12:58,360 We can burn our carbon in oxygen and we'll get, what would we get? 222 00:12:58,360 --> 00:13:02,360 Carbon dioxide. See? He's pretty good. Carbon dioxide. 223 00:13:02,360 --> 00:13:05,880 And then if we bubble that through lime water? Calcium carbonate. 224 00:13:05,880 --> 00:13:08,800 Calcium carbonate. That's the test for carbon dioxide, of course. 225 00:13:08,800 --> 00:13:11,160 And it would be white. I didn't ask you that one. 226 00:13:11,160 --> 00:13:15,400 You are getting carried away now. Let's just see this over here. 227 00:13:15,400 --> 00:13:16,840 We have some apparatus. 228 00:13:16,840 --> 00:13:20,680 This is where we are going to burn some graphite 229 00:13:20,680 --> 00:13:23,320 and show that it is made of carbon. 230 00:13:23,320 --> 00:13:25,640 What's bubbling through here is just oxygen. 231 00:13:25,640 --> 00:13:29,320 This won't react with our lime water at all. 232 00:13:29,320 --> 00:13:33,280 We are going to see if we can light the graphite 233 00:13:33,280 --> 00:13:38,160 and get it burning inside the oxygen. There we are. Thank you. 234 00:13:38,160 --> 00:13:41,520 That's great. So now we have a hydrogen flame. 235 00:13:41,520 --> 00:13:44,840 This won't produce anything. It's only going to produce water. 236 00:13:44,840 --> 00:13:48,440 You can see the water just beginning to condense. 237 00:13:48,440 --> 00:13:51,160 Beautiful. I'm going to turn the flame off. 238 00:13:52,960 --> 00:13:55,600 Look at that. What do you think? It's brilliant. 239 00:13:55,600 --> 00:13:57,320 It is literally brilliant, yes. 240 00:13:57,320 --> 00:14:02,960 This is the carbon combining with oxygen that's flowing through here. 241 00:14:02,960 --> 00:14:06,600 Hopefully, we are going to see this changing colour, giving us 242 00:14:06,600 --> 00:14:10,040 a milky colour. Showing that there is carbon dioxide present. 243 00:14:10,040 --> 00:14:13,720 I think we should test diamond as well, don't you? What do you think? 244 00:14:13,720 --> 00:14:15,520 ALL: Yes! 245 00:14:15,520 --> 00:14:18,000 Yes? Does Mrs Kroto mind? 246 00:14:18,000 --> 00:14:21,120 OK. In the name of science. That's very kind of you. 247 00:14:21,120 --> 00:14:24,280 Harry seems a little nervous. Are you sure this is a real diamond? 248 00:14:24,280 --> 00:14:27,720 I think it's a real diamond, yes. Let's give it a go then. 249 00:14:27,720 --> 00:14:31,680 We will just put it on there. And again, we'll put this on here. 250 00:14:34,080 --> 00:14:39,720 Right, so we have our flame. Here we go. The moment of truth. 251 00:14:39,720 --> 00:14:44,960 Now can we get our diamond to burn in the oxygen? 252 00:14:46,200 --> 00:14:47,960 WATER BUBBLES 253 00:14:54,720 --> 00:14:57,680 Ah, look at that! 254 00:14:57,680 --> 00:15:00,520 I hope you can afford to pay for this. 255 00:15:00,520 --> 00:15:03,200 The good news is, Harry, it is a real diamond. 256 00:15:03,200 --> 00:15:04,680 LAUGHTER 257 00:15:04,680 --> 00:15:05,880 OK. 258 00:15:07,520 --> 00:15:09,600 I think this is absolutely stunning. 259 00:15:09,600 --> 00:15:13,920 That diamond there, it is burning in oxygen. 260 00:15:13,920 --> 00:15:16,280 It's combining with the oxygen of the air. 261 00:15:16,280 --> 00:15:19,280 Have you ever seen a diamond burning like that before? No, I haven't. 262 00:15:19,280 --> 00:15:21,560 It is quite stunning to see. That's right. 263 00:15:21,560 --> 00:15:23,960 There are no flames coming from this. 264 00:15:23,960 --> 00:15:28,680 So this is just the heat of the reaction as the carbon combines 265 00:15:28,680 --> 00:15:32,320 with the oxygen that's present, flowing through here, 266 00:15:32,320 --> 00:15:35,840 forming carbon dioxide. That is absolutely stunning. 267 00:15:35,840 --> 00:15:38,040 Just look at that. It's glowing all by itself. 268 00:15:38,040 --> 00:15:41,480 It's absolutely brilliant. I think that's amazing. 269 00:15:41,480 --> 00:15:45,520 And look, our lime water is going milky. 270 00:15:45,520 --> 00:15:49,000 It's the most expensive lime water I've ever seen. 271 00:15:49,000 --> 00:15:50,800 I think you are probably right there. 272 00:15:50,800 --> 00:15:53,720 It really is the most expensive lime water you've ever seen. 273 00:15:53,720 --> 00:15:57,680 Well, we are waiting for your diamond just to... Disappear. 274 00:15:57,680 --> 00:15:59,760 To disappear, yes. 275 00:15:59,760 --> 00:16:02,840 Maybe you could tell us about your Nobel Prize again. 276 00:16:02,840 --> 00:16:07,240 I think it has something to do with this. I think it does, yes. 277 00:16:07,240 --> 00:16:09,680 Would you like to come round to the front, actually. 278 00:16:09,680 --> 00:16:11,360 We'll compare it to these ones. 279 00:16:11,360 --> 00:16:15,200 This one was the graphite. This is the diamond. 280 00:16:15,200 --> 00:16:19,040 And this is the third form, the well-characterised form. 281 00:16:19,040 --> 00:16:23,600 It consists of 60 carbon atoms in the shape of a soccer ball. 282 00:16:23,600 --> 00:16:26,920 And it was such a fantastic surprise when we discovered it. 283 00:16:26,920 --> 00:16:32,040 One of the clues to its structure was Mr Fuller's geodesic domes. 284 00:16:32,040 --> 00:16:36,440 In Montreal, we had visited that. And I remembered it. 285 00:16:36,440 --> 00:16:38,120 It was in a book of mine 286 00:16:38,120 --> 00:16:43,000 and when we were trying to work out how a sheet of graphite like this, 287 00:16:43,000 --> 00:16:46,600 or a graphing sheet, might close up, 288 00:16:46,600 --> 00:16:50,920 what we discovered was, it could close up if it had 12 pentagons. 289 00:16:50,920 --> 00:16:54,800 You cannot close a sheet of hexagons up. It won't close up. 290 00:16:54,800 --> 00:16:57,040 But if you have 12 pentagons, it will. 291 00:16:57,040 --> 00:17:00,480 And you are all familiar with that in the case of the normal 292 00:17:00,480 --> 00:17:05,280 soccer ball with 12 black pentagons and 20 hexagons. 293 00:17:05,280 --> 00:17:09,360 And that's the magic that Mr Fuller knew, and other people as well. 294 00:17:09,360 --> 00:17:12,920 And I called it Buckminsterfullerene 295 00:17:12,920 --> 00:17:16,080 because there are double bonds as there are in benzene. 296 00:17:16,080 --> 00:17:20,040 So the "ene" ending was just a beautiful sort of ending 297 00:17:20,040 --> 00:17:21,840 to a great name. 298 00:17:21,840 --> 00:17:26,200 So since my time at school, the textbooks have to be rewritten 299 00:17:26,200 --> 00:17:30,000 with a new form of carbon discovered by this chap here. 300 00:17:30,000 --> 00:17:34,320 And colleagues in the States. And your co-workers in the States. 301 00:17:34,320 --> 00:17:37,480 We should have another look at your diamond here. 302 00:17:37,480 --> 00:17:40,440 It seems to have decreased in size. 303 00:17:40,440 --> 00:17:42,040 I think we should come clean. 304 00:17:42,040 --> 00:17:46,120 Don't worry, we didn't destroy Mrs Kroto's engagement ring. 305 00:17:46,120 --> 00:17:51,480 That really would be quite harsh. This is a pretty low-grade diamond. 306 00:17:51,480 --> 00:17:53,960 It still looks pretty good to the naked eye 307 00:17:53,960 --> 00:17:56,520 but the experts say it's not very valuable at all. 308 00:17:56,520 --> 00:17:58,160 But it is a real diamond. 309 00:17:58,160 --> 00:18:00,000 And it is combining with oxygen 310 00:18:00,000 --> 00:18:03,640 and I think that's a pretty stunning reaction. Thank you, Prof Kroto. 311 00:18:03,640 --> 00:18:06,080 It's a real privilege to have a Nobel Prize winner here, 312 00:18:06,080 --> 00:18:08,600 helping out with an experiment. Thank you very much. 313 00:18:08,600 --> 00:18:10,120 APPLAUSE 314 00:18:13,400 --> 00:18:18,240 So is it possible that we could take this worthless carbon dioxide 315 00:18:18,240 --> 00:18:21,000 and get our diamond back from that? 316 00:18:21,000 --> 00:18:24,080 I mean, that really would be the alchemist's dream. 317 00:18:24,080 --> 00:18:26,880 Recovering something precious from something worthless. 318 00:18:26,880 --> 00:18:31,080 We've got a demonstration here that shows that this may be possible. 319 00:18:31,080 --> 00:18:32,880 I'll just turn this round. 320 00:18:34,760 --> 00:18:39,200 Now this tank is filled with carbon dioxide gas. 321 00:18:39,200 --> 00:18:42,040 We've put some solid carbon dioxide in the bottom, 322 00:18:42,040 --> 00:18:45,280 which is slowly evaporating, turning into the gas. 323 00:18:45,280 --> 00:18:48,040 We can't see the gas because, of course, it's colourless. 324 00:18:48,040 --> 00:18:51,000 But it is there. How can we test for this? 325 00:18:51,000 --> 00:18:54,000 Does anyone know another use for carbon dioxide? Yes? 326 00:18:54,000 --> 00:18:56,520 To put out flames. To put out flames, yes, exactly. 327 00:18:56,520 --> 00:19:00,320 I wonder if we have a flame, please. Is there a flame anywhere? 328 00:19:00,320 --> 00:19:05,800 Ah, yes. Here is a flame that certainly needs putting out. 329 00:19:05,800 --> 00:19:08,560 If I just lower this into the tank... 330 00:19:11,280 --> 00:19:13,560 There we are. You can see that it goes out. 331 00:19:13,560 --> 00:19:17,400 This is because, of course, the tank is filled with carbon dioxide. 332 00:19:17,400 --> 00:19:20,200 And carbon dioxide doesn't support combustion. 333 00:19:21,560 --> 00:19:27,640 Right, now then. We have also placed in this tank some magnesium metal. 334 00:19:27,640 --> 00:19:30,200 I'm just going to fish this out. 335 00:19:33,240 --> 00:19:36,880 This is a little nest of magnesium metal. 336 00:19:36,880 --> 00:19:39,440 I'm going to light the magnesium here 337 00:19:39,440 --> 00:19:43,040 and it burns with a brilliant white flame. There we are. 338 00:19:43,040 --> 00:19:46,840 Now I'm going to lower this into the carbon dioxide. 339 00:19:46,840 --> 00:19:49,840 It seems to be burning even more vigorously now. 340 00:19:49,840 --> 00:19:52,080 The flame is still burning. 341 00:19:54,440 --> 00:19:58,800 But what about this? This one...well, this one still goes out. 342 00:20:00,320 --> 00:20:05,120 Our petrol is extinguished in the carbon dioxide, 343 00:20:05,120 --> 00:20:08,000 but the magnesium is reacting with it. 344 00:20:08,000 --> 00:20:13,040 The magnesium is stealing the oxygen away from the carbon dioxide 345 00:20:13,040 --> 00:20:16,320 and, well, we'll have a look at what we've got at the bottom 346 00:20:16,320 --> 00:20:19,480 but let me take this out. You can see magnesium oxide 347 00:20:19,480 --> 00:20:22,200 covered over what was the magnesium here, 348 00:20:22,200 --> 00:20:26,880 but look in the centre. What we've now got is black carbon. 349 00:20:28,880 --> 00:20:33,320 The magnesium removes the oxygen leaving behind the carbon 350 00:20:33,320 --> 00:20:35,200 from the carbon dioxide. 351 00:20:35,200 --> 00:20:38,680 We can get our carbon back from carbon dioxide 352 00:20:38,680 --> 00:20:43,320 but, well, it's not a diamond yet. 353 00:20:43,320 --> 00:20:47,960 Is it possible to turn that carbon into a diamond? 354 00:20:47,960 --> 00:20:52,840 Well, actually, this is what happens deep within the earth, 355 00:20:52,840 --> 00:20:56,120 and this is a diamond in a rock 356 00:20:56,120 --> 00:21:00,760 just as it would have come out of the earth. 357 00:21:00,760 --> 00:21:03,000 This is really quite beautiful indeed. 358 00:21:03,000 --> 00:21:06,960 Deep within the earth, the carbon is heated up 359 00:21:06,960 --> 00:21:09,920 and compressed with huge temperatures, huge pressures, 360 00:21:09,920 --> 00:21:12,920 and the carbon we saw there, the black carbon, 361 00:21:12,920 --> 00:21:16,760 is converted into diamond. 362 00:21:16,760 --> 00:21:20,080 Recently, chemists have learnt how to copy this process, 363 00:21:20,080 --> 00:21:24,880 how to turn graphite or other forms of carbon into diamond. 364 00:21:24,880 --> 00:21:29,080 I'd like a volunteer to help me out with this one, please. 365 00:21:29,080 --> 00:21:32,840 Would you like to come down to the front, please? 366 00:21:32,840 --> 00:21:35,320 APPLAUSE 367 00:21:35,320 --> 00:21:38,360 If you'd like to come down to the front. Your name is...? 368 00:21:38,360 --> 00:21:43,040 Lewis. Lewis, OK. Now, this is a diamond. 369 00:21:43,040 --> 00:21:46,080 Would you like to just hold this? 370 00:21:46,080 --> 00:21:48,520 What do you think, are you impressed? Yeah. 371 00:21:48,520 --> 00:21:52,120 Looks like a piece of glass, doesn't it? It actually really is a diamond. 372 00:21:52,120 --> 00:21:55,200 This is a synthetically grown diamond and this has been prepared 373 00:21:55,200 --> 00:21:59,040 not from the high temperature, high pressure system that we also use, 374 00:21:59,040 --> 00:22:02,000 this is a technique called chemical vapour deposition 375 00:22:02,000 --> 00:22:05,080 where the diamond is gradually built up a layer at a time. 376 00:22:05,080 --> 00:22:09,440 I'd like you to take this, not keep it, but bring it over here 377 00:22:09,440 --> 00:22:11,400 and just place it on top. 378 00:22:11,400 --> 00:22:14,720 This is some ice here. Hold it like this. 379 00:22:14,720 --> 00:22:19,680 Just put that on top of there and push through this ice. 380 00:22:19,680 --> 00:22:23,400 How does that feel? Cold. It feels very cold and what's happening? 381 00:22:23,400 --> 00:22:25,480 Water's coming off. 382 00:22:25,480 --> 00:22:28,920 This is ice, solid ice, and it seems to be going... 383 00:22:28,920 --> 00:22:32,040 You've chopped all the way through this quite cleanly there. 384 00:22:32,040 --> 00:22:33,800 As you say, it's got very cold. 385 00:22:33,800 --> 00:22:36,240 Do you know why it's got colder? No idea. 386 00:22:36,240 --> 00:22:39,160 It's used your energy to heat up this block of ice, 387 00:22:39,160 --> 00:22:42,400 so yes, you're getting cold because it's taking the energy 388 00:22:42,400 --> 00:22:44,960 from your fingers here. Let's try this again. 389 00:22:44,960 --> 00:22:48,400 If I just put this on here, it slices through like butter. 390 00:22:48,400 --> 00:22:51,080 It's really quite amazing. It feels very strange. 391 00:22:51,080 --> 00:22:55,000 I'm not sawing. It's not cutting because it's hard, 392 00:22:55,000 --> 00:22:58,440 it's cutting because it's a very good conductor of heat. 393 00:22:58,440 --> 00:23:01,640 Quite remarkable, so cleanly through this block of ice. 394 00:23:01,640 --> 00:23:04,720 Feels very strange. Thank you very much, thank you for that. 395 00:23:04,720 --> 00:23:07,720 APPLAUSE 396 00:23:09,120 --> 00:23:11,120 That remarkable property of diamond 397 00:23:11,120 --> 00:23:14,320 was because it's an incredible conductor of heat. 398 00:23:14,320 --> 00:23:17,280 To demonstrate this and explain why this is so, 399 00:23:17,280 --> 00:23:20,120 I'd like some other volunteers, please. 400 00:23:20,120 --> 00:23:23,480 I'd like six people so if we could have all of you, six of you, 401 00:23:23,480 --> 00:23:26,000 if you could come down to the front, please? 402 00:23:26,000 --> 00:23:30,800 In a row, facing the audience. Sit next to each other. 403 00:23:30,800 --> 00:23:33,920 I'd like all of you to face that direction, please, 404 00:23:33,920 --> 00:23:35,920 turn around and face that way. 405 00:23:35,920 --> 00:23:38,720 Just close up a little bit, a little bit friendlier. 406 00:23:38,720 --> 00:23:42,040 Come this way, please. Lovely job. Close up there 407 00:23:42,040 --> 00:23:45,680 and put your hands on the shoulders of the person in front. 408 00:23:45,680 --> 00:23:47,600 Face that way. That's good. 409 00:23:47,600 --> 00:23:51,400 Now, at the moment, these are all pretty weak bonds here. 410 00:23:51,400 --> 00:23:54,240 Watch what happens when I give a bit of energy this way. 411 00:23:54,240 --> 00:23:56,640 Don't do anything, just behave normally. 412 00:23:56,640 --> 00:23:59,520 Lucy, can you feel anything? 413 00:23:59,520 --> 00:24:02,400 It was very difficult to get this energy through there 414 00:24:02,400 --> 00:24:04,960 and this is because of all these weak bonds. 415 00:24:04,960 --> 00:24:08,560 What I'd like you to do is just spread yourselves out a little more 416 00:24:08,560 --> 00:24:11,280 and hold arms with very rigid arms. 417 00:24:11,280 --> 00:24:14,560 Rigid, straight arms. That's it. 418 00:24:14,560 --> 00:24:17,560 Now I'm just going to do the same thing again. 419 00:24:17,560 --> 00:24:22,280 Give you a jolt that end and now you can see you're certainly moving. 420 00:24:22,280 --> 00:24:25,720 Thank you very much indeed, thank you for all your help. 421 00:24:25,720 --> 00:24:27,960 APPLAUSE 422 00:24:27,960 --> 00:24:34,040 This is why our diamond is such a good conductor of thermal energy. 423 00:24:34,040 --> 00:24:38,840 It's because the bonds are so strong holding these carbon atoms together, 424 00:24:38,840 --> 00:24:43,600 they're so rigid, that this energy is very easily transmitted through. 425 00:24:43,600 --> 00:24:47,080 Diamond is the best conductor of heat of any substance known, 426 00:24:47,080 --> 00:24:51,120 until very recently when scientists discovered a new form of carbon, 427 00:24:51,120 --> 00:24:54,880 another form, called graphene, which is a single sheet of graphite. 428 00:24:54,880 --> 00:24:59,600 That is an even better conductor of heat. They're the best ones known. 429 00:25:01,840 --> 00:25:05,160 We've seen then that we can convert charcoal, 430 00:25:05,160 --> 00:25:09,280 we convert graphite into diamond under very high pressures 431 00:25:09,280 --> 00:25:12,240 or using the other technique of chemical vapour deposition. 432 00:25:12,240 --> 00:25:16,720 Surely if the alchemists had focused on that, they would have changed 433 00:25:16,720 --> 00:25:20,920 their attention away from trying to turn base metals into gold. 434 00:25:20,920 --> 00:25:24,000 But of course, they were focused on metals because metals 435 00:25:24,000 --> 00:25:26,960 were incredibly important and still are very important. 436 00:25:26,960 --> 00:25:29,280 It's only gold that has this unique property 437 00:25:29,280 --> 00:25:33,800 that we can find it lying around. Most metals we find in their ores. 438 00:25:33,800 --> 00:25:36,440 Ores like this here. 439 00:25:36,440 --> 00:25:41,480 This is the natural mineral - does anybody know what it is? 440 00:25:41,480 --> 00:25:43,280 It is an iron ore. 441 00:25:43,280 --> 00:25:47,160 Does anyone know what the name of the iron ore would be? 442 00:25:47,160 --> 00:25:49,560 Very good, you're doing well. Hematite it is. 443 00:25:49,560 --> 00:25:52,160 This is the mineral hematite. 444 00:25:52,160 --> 00:25:54,920 This is now our source for iron 445 00:25:54,920 --> 00:25:59,760 but it's locked up with the iron combined with oxygen. 446 00:25:59,760 --> 00:26:03,960 Somehow we have to learn how to extract the metal out of this. 447 00:26:03,960 --> 00:26:07,080 After all, it doesn't just fall from the skies. 448 00:26:07,080 --> 00:26:12,160 But remarkably, sometimes it does just fall from the skies 449 00:26:12,160 --> 00:26:14,960 and this is what we have here. 450 00:26:14,960 --> 00:26:17,640 This is actually very heavy as well. 451 00:26:17,640 --> 00:26:23,360 This is a lump of iron that did fall from the skies about 5,000 years ago 452 00:26:23,360 --> 00:26:27,000 and it landed in Australia. Look at this. 453 00:26:27,000 --> 00:26:30,360 What I wanted to show you here was the comparison 454 00:26:30,360 --> 00:26:32,080 between these two pieces. 455 00:26:32,080 --> 00:26:37,520 We can see that this is developing this reddish-brown colour, 456 00:26:37,520 --> 00:26:39,920 the same as the hematite. 457 00:26:39,920 --> 00:26:42,440 This contains iron. It is a slice of iron 458 00:26:42,440 --> 00:26:45,280 but it is gradually combining with oxygen 459 00:26:45,280 --> 00:26:47,520 to form this mineral hematite. 460 00:26:47,520 --> 00:26:49,960 We can show that it is a meteorite 461 00:26:49,960 --> 00:26:52,840 if we were to take a slice through this. 462 00:26:52,840 --> 00:26:55,640 If we took a slice through this, 463 00:26:55,640 --> 00:26:59,480 what we would see is something like this. 464 00:26:59,480 --> 00:27:06,000 This is a slice through a meteorite and it's really quite beautiful. 465 00:27:06,000 --> 00:27:08,440 This has been cut and we can see the side here. 466 00:27:08,440 --> 00:27:10,680 This is the outer surface of the meteorite 467 00:27:10,680 --> 00:27:14,120 and here it's been cut with this incredible pattern here. 468 00:27:14,120 --> 00:27:18,400 This pattern has been etched with acid. 469 00:27:18,400 --> 00:27:22,560 It etches away certain types of the minerals that are in here. 470 00:27:22,560 --> 00:27:25,720 The forms of the iron, it etches away certain of them 471 00:27:25,720 --> 00:27:28,760 and it reveals this beautiful crystal structure 472 00:27:28,760 --> 00:27:31,160 and this proves that it's a meteorite, 473 00:27:31,160 --> 00:27:34,880 because it's impossible to get this pattern here on Earth. 474 00:27:34,880 --> 00:27:37,040 That's because we need to cool down molten iron 475 00:27:37,040 --> 00:27:39,080 with a little bit of nickel in. 476 00:27:39,080 --> 00:27:41,960 We'd need to cool it down over such a slow rate, 477 00:27:41,960 --> 00:27:44,600 just one degree over thousands of years, 478 00:27:44,600 --> 00:27:47,440 if we wanted to see these crystals develop. 479 00:27:47,440 --> 00:27:51,520 This really is quite stunning indeed. 480 00:27:51,520 --> 00:27:55,840 Over time, the metal of this beautiful meteorite 481 00:27:55,840 --> 00:27:58,720 will turn into this ore here. 482 00:27:58,720 --> 00:28:01,480 We can't wait thousands of years to see that 483 00:28:01,480 --> 00:28:03,520 but we can speed this process up 484 00:28:03,520 --> 00:28:08,000 and we can show how iron combines with the oxygen to form iron oxide. 485 00:28:08,000 --> 00:28:10,880 I'd like a volunteer for this one, please. 486 00:28:10,880 --> 00:28:13,440 I'd like someone from this side, who shall we have? 487 00:28:13,440 --> 00:28:15,840 Would you like to come down to the front, please? 488 00:28:15,840 --> 00:28:19,080 APPLAUSE 489 00:28:19,080 --> 00:28:22,040 Would you like to tell us your name, please? Rose. 490 00:28:22,040 --> 00:28:25,600 Rose, OK, we have some iron over here. This is just iron wool. 491 00:28:25,600 --> 00:28:27,040 Would you like to feel this? 492 00:28:27,040 --> 00:28:29,880 It's just the sort of thing you would use to clean your pots 493 00:28:29,880 --> 00:28:31,920 and pans if you're helping out at home. 494 00:28:31,920 --> 00:28:33,760 Now, I'll put on my goggles 495 00:28:33,760 --> 00:28:37,400 and we're going to combine this with some oxygen. 496 00:28:37,400 --> 00:28:43,080 We want to see how much this weighs by itself. This weighs 15.9 grams. 497 00:28:43,080 --> 00:28:45,520 Now, the question is, what will happen 498 00:28:45,520 --> 00:28:48,160 when this combines with the oxygen from the air? 499 00:28:48,160 --> 00:28:50,400 How do you think its mass will change? 500 00:28:50,400 --> 00:28:52,600 Will it go up, go down, stay the same? 501 00:28:52,600 --> 00:28:54,680 What do you think, when it burns? 502 00:28:54,680 --> 00:28:57,320 It will go up? It will go up, and why's that? 503 00:28:57,320 --> 00:29:01,680 Because it will become more dense. It will become more dense. 504 00:29:01,680 --> 00:29:03,880 Let's have a look and see, shall we? 505 00:29:03,880 --> 00:29:06,280 I'm just going to apply a light here. 506 00:29:06,280 --> 00:29:10,080 This beautiful reaction is the iron combining with the oxygen 507 00:29:10,080 --> 00:29:12,520 and look what's happened to the mass. 508 00:29:12,520 --> 00:29:15,800 It's gone down. It's getting lower. 509 00:29:15,800 --> 00:29:19,680 -0.16, so whoever said it goes down, you're quite right. 510 00:29:19,680 --> 00:29:22,880 But look now what's happening. It's going up again. 511 00:29:22,880 --> 00:29:26,280 It's is getting heavier so whoever said it goes up, you're quite right. 512 00:29:26,280 --> 00:29:29,000 Everyone's right, that's good. Why did it go down? 513 00:29:29,000 --> 00:29:33,520 It went down initially because this iron wool was treated with oil, 514 00:29:33,520 --> 00:29:37,920 just to try and stop it combining with the oxygen from the air. 515 00:29:37,920 --> 00:29:41,160 Once this reaction has started, it is combining with oxygen 516 00:29:41,160 --> 00:29:44,360 and that's why it's getting heavier. You were quite right. 517 00:29:44,360 --> 00:29:48,200 It is getting heavier because the iron is forming iron oxide. 518 00:29:48,200 --> 00:29:50,440 Thank you very much indeed. 519 00:29:50,440 --> 00:29:53,360 APPLAUSE 520 00:29:55,360 --> 00:29:57,240 Iron is pretty reactive stuff. 521 00:29:57,240 --> 00:29:59,520 It reacts with oxygen and this is how 522 00:29:59,520 --> 00:30:03,280 we would normally find our metal, combined with oxygen. 523 00:30:03,280 --> 00:30:07,160 What about if you couldn't extract the iron from this? 524 00:30:07,160 --> 00:30:09,560 What about before we knew how to do this? 525 00:30:09,560 --> 00:30:12,480 The only iron that we would have had would have been iron 526 00:30:12,480 --> 00:30:14,960 from a natural source such as this meteorite. 527 00:30:14,960 --> 00:30:19,160 This sort of iron was used to make tools and so on. 528 00:30:19,160 --> 00:30:23,520 I think we have an example of a tool using some natural iron here. 529 00:30:23,520 --> 00:30:25,600 Would you please welcome Dr Caroline Smith 530 00:30:25,600 --> 00:30:27,880 from the Natural History Museum. 531 00:30:27,880 --> 00:30:30,280 APPLAUSE 532 00:30:32,160 --> 00:30:34,800 This is really beautiful. What exactly is this? 533 00:30:34,800 --> 00:30:39,080 This is an Inuit knife and it's made of walrus tusk, 534 00:30:39,080 --> 00:30:43,440 so walrus ivory, but in the end you can hopefully see 535 00:30:43,440 --> 00:30:46,080 it actually has an iron blade. 536 00:30:46,080 --> 00:30:49,040 When this was discovered, the Inuits hadn't yet learnt 537 00:30:49,040 --> 00:30:51,880 how to make iron, how to extract it from the ore. 538 00:30:51,880 --> 00:30:55,320 That's right. They had to have a source of metallic iron. 539 00:30:55,320 --> 00:30:58,560 At the time, it was thought that the iron in this knife 540 00:30:58,560 --> 00:31:02,120 was actually from a meteorite called the Cape York meteorite, 541 00:31:02,120 --> 00:31:05,080 a very large meteorite which was found in Greenland. 542 00:31:05,080 --> 00:31:07,400 This knife actually came from Greenland, 543 00:31:07,400 --> 00:31:09,760 but we're not actually sure that's right, now, 544 00:31:09,760 --> 00:31:12,000 we think it might be from somewhere else. 545 00:31:12,000 --> 00:31:14,840 I gather that you've performed an analysis on this 546 00:31:14,840 --> 00:31:18,480 and more research suggests that you are beginning to question 547 00:31:18,480 --> 00:31:21,720 whether this is a meteorite, but it has to be naturally occurring 548 00:31:21,720 --> 00:31:23,960 because they didn't have the technology. 549 00:31:23,960 --> 00:31:27,000 Exactly. They didn't have the technology to extract iron 550 00:31:27,000 --> 00:31:29,800 from things like hematite so they had to have a source 551 00:31:29,800 --> 00:31:31,680 of native iron, metallic iron. 552 00:31:31,680 --> 00:31:34,480 We think now that maybe this is actually from a place 553 00:31:34,480 --> 00:31:35,800 called Disko Island, 554 00:31:35,800 --> 00:31:38,560 which is an island off the west coast of Greenland, 555 00:31:38,560 --> 00:31:41,720 and it's one of the very few locations on earth 556 00:31:41,720 --> 00:31:45,760 where you get metallic iron existing in metallic form. 557 00:31:45,760 --> 00:31:49,320 You very kindly brought a couple of samples for us. 558 00:31:49,320 --> 00:31:52,600 These are from Disko Island. 559 00:31:52,600 --> 00:31:56,680 They look quite different but this one clearly looks very metallic. 560 00:31:56,680 --> 00:31:59,320 You can see this here, it's got quite a shine to it. 561 00:31:59,320 --> 00:32:02,080 It's quite a heavy specimen. It is very heavy. 562 00:32:02,080 --> 00:32:05,920 This looks like a piece of iron but this is naturally occurring iron? 563 00:32:05,920 --> 00:32:09,440 This is naturally occurring iron found at the surface of the Earth. 564 00:32:09,440 --> 00:32:12,000 In fact, tons of this iron has been found. 565 00:32:12,000 --> 00:32:15,720 But why hasn't this one corroded into the hematite? 566 00:32:15,720 --> 00:32:19,600 What we think happened is that about 55 million years ago, 567 00:32:19,600 --> 00:32:22,240 lava was erupted in this place, in Disko Island, 568 00:32:22,240 --> 00:32:24,280 and as the lava was coming up, 569 00:32:24,280 --> 00:32:28,640 it went through sedimentary rocks that have got a lot of carbon in, 570 00:32:28,640 --> 00:32:30,480 and the lava picked the carbon up 571 00:32:30,480 --> 00:32:33,960 and you've got a chemical reaction happening where the iron, 572 00:32:33,960 --> 00:32:37,160 which was bonded with oxygen just like here in the hematite, 573 00:32:37,160 --> 00:32:41,160 actually became metallic iron. It reduced the iron from the lava. 574 00:32:41,160 --> 00:32:44,600 We can see this is also a sample of iron, so this is iron. 575 00:32:44,600 --> 00:32:47,440 This is a sample of lava from Disko Island 576 00:32:47,440 --> 00:32:51,160 so there is some metal in there but not as big as that. 577 00:32:51,160 --> 00:32:54,360 This one is a very grey colour and that's due to the graphite 578 00:32:54,360 --> 00:32:55,800 and carbon in here? 579 00:32:55,800 --> 00:32:59,160 You can see a bit of a smudge on the paper. 580 00:32:59,160 --> 00:33:00,960 There's a black smear there. 581 00:33:00,960 --> 00:33:04,520 That's just from the carbon that's present in here, the graphite? 582 00:33:04,520 --> 00:33:08,520 That's right. Actually, we've got a clip of a blast furnace to show. 583 00:33:08,520 --> 00:33:11,000 This is how iron is now manufactured 584 00:33:11,000 --> 00:33:15,680 and this is using carbon to steal away the oxygen from the iron ore, 585 00:33:15,680 --> 00:33:16,920 from the hematite. 586 00:33:16,920 --> 00:33:19,760 This is how we're producing iron but what you're saying now is that... 587 00:33:19,760 --> 00:33:23,120 Nature beat us to it about 55 million years ago. 588 00:33:23,120 --> 00:33:25,440 Exactly. That is quite amazing. 589 00:33:25,440 --> 00:33:29,640 Thank you very much for bringing these samples on. 590 00:33:33,360 --> 00:33:37,000 Now, I really wanted to produce some molten iron for you 591 00:33:37,000 --> 00:33:40,480 here in the lecture theatre, but clearly we couldn't bring in 592 00:33:40,480 --> 00:33:43,520 a blast furnace, so we had to think of another way to do this. 593 00:33:43,520 --> 00:33:46,160 We can learn from what we did earlier, 594 00:33:46,160 --> 00:33:49,880 when we used the magnesium metal to steal the oxygen away 595 00:33:49,880 --> 00:33:51,680 from the carbon dioxide. 596 00:33:51,680 --> 00:33:54,440 We can do the same thing now with our iron oxide. 597 00:33:54,440 --> 00:33:56,640 We can use a more reactive metal 598 00:33:56,640 --> 00:33:59,760 and we are going to use the metal, aluminium. 599 00:33:59,760 --> 00:34:04,800 You may be wondering why there's a safe under here. 600 00:34:04,800 --> 00:34:08,200 This is because we have a bit of an embarrassing story here. 601 00:34:08,200 --> 00:34:14,760 We accidentally locked Andy's Christmas bonus in the safe. 602 00:34:14,760 --> 00:34:18,360 We tried getting into the safe and it's pretty hard. 603 00:34:18,360 --> 00:34:24,280 It's made of pretty solid stuff. We can't really get into this 604 00:34:24,280 --> 00:34:28,280 but the energy generated as the oxygen is taken away 605 00:34:28,280 --> 00:34:32,840 by the aluminium to form iron should be enough to get in here. 606 00:34:32,840 --> 00:34:34,880 Can we have a little look in here? 607 00:34:34,880 --> 00:34:38,360 Get the camera right in to show what's inside this vessel. 608 00:34:38,360 --> 00:34:42,400 This is made of a very tough form of carbon. This is made of graphite, 609 00:34:42,400 --> 00:34:45,080 and you may be able to see the orangey colour. 610 00:34:45,080 --> 00:34:49,720 That's our iron oxide. It's mixed with aluminium powder. 611 00:34:49,720 --> 00:34:53,400 The thing you see sticking out there is a little bit of magnesium 612 00:34:53,400 --> 00:34:55,640 I'm going to use to start this reaction. 613 00:34:55,640 --> 00:34:58,040 Hopefully, we should generate some iron 614 00:34:58,040 --> 00:35:00,480 and see if we can get through into the safe. 615 00:35:00,480 --> 00:35:04,160 Sounds like a good idea, doesn't it? If it's the only way to do it. 616 00:35:04,160 --> 00:35:08,880 I think we will need a safety screen around this, though. 617 00:35:08,880 --> 00:35:14,720 I'm going to need a glove as well. Thank you very much. 618 00:35:14,720 --> 00:35:18,360 Feeling confident? Yeah, I can't see what could go wrong. 619 00:35:18,360 --> 00:35:20,800 What could possibly go wrong? Exactly. 620 00:35:20,800 --> 00:35:24,440 Let's give it a go. You'll see a bright white light first of all. 621 00:35:24,440 --> 00:35:26,640 That's just the magnesium we saw earlier. 622 00:35:26,640 --> 00:35:29,520 The magnesium combining with the oxygen from the air. 623 00:35:32,120 --> 00:35:37,040 OK. We should know when it starts. I think it's started now! 624 00:35:37,040 --> 00:35:41,120 This is our little blast furnace here. Look at that, fantastic. 625 00:35:41,120 --> 00:35:44,360 We've got some molten metal there. Can we lose the safety screen? 626 00:35:44,360 --> 00:35:47,760 That would be good if we can possibly take this off. Lovely job. 627 00:35:47,760 --> 00:35:53,200 Right off the top very carefully. I'm just going to see... 628 00:35:53,200 --> 00:35:56,720 I'll give you that, see if we can pick up this. 629 00:35:56,720 --> 00:35:59,800 What have we got here? Yes, that's wonderful. 630 00:35:59,800 --> 00:36:02,800 It releases such an enormous amount of energy 631 00:36:02,800 --> 00:36:06,920 as the aluminium combines with the oxygen from the iron oxide. 632 00:36:06,920 --> 00:36:09,360 Good news, Andy. Good news and bad news. 633 00:36:09,360 --> 00:36:12,800 The good news is there's a hole in the top of the safe. 634 00:36:12,800 --> 00:36:16,480 The bad news is there's a lot of smoke coming from outside. 635 00:36:16,480 --> 00:36:19,760 I think I've just found the key as well! 636 00:36:19,760 --> 00:36:22,920 Now he finds the key! At least we got into the safe, well done. 637 00:36:22,920 --> 00:36:25,800 Thank you very much for that. 638 00:36:25,800 --> 00:36:27,840 APPLAUSE 639 00:36:27,840 --> 00:36:31,120 We formed there during that reaction aluminium oxide 640 00:36:31,120 --> 00:36:33,600 as the aluminium took the oxygen away. 641 00:36:33,600 --> 00:36:36,400 This is how we find aluminium in nature. 642 00:36:36,400 --> 00:36:40,320 We find it as aluminium oxide and here's a sample here. 643 00:36:40,320 --> 00:36:43,480 What do you think of that? 644 00:36:43,480 --> 00:36:47,920 It is light and this is because it's a very light metal, aluminium. 645 00:36:47,920 --> 00:36:52,640 How can we get our aluminium out of this rock? 646 00:36:52,640 --> 00:36:56,080 This, for a long time, was a great problem. 647 00:36:56,080 --> 00:37:00,160 It was only solved when chemists realised they could use 648 00:37:00,160 --> 00:37:04,280 an even more reactive metal and this was the metal over here, 649 00:37:04,280 --> 00:37:05,800 the metal potassium. 650 00:37:05,800 --> 00:37:09,080 When this was first discovered, it was a bit of a curiosity. 651 00:37:09,080 --> 00:37:11,520 There was this amazing substance, aluminium, 652 00:37:11,520 --> 00:37:13,960 and it did have very remarkable properties. 653 00:37:13,960 --> 00:37:16,600 I'll need another volunteer from the audience. 654 00:37:16,600 --> 00:37:18,000 We'll have someone this side. 655 00:37:18,000 --> 00:37:21,200 In the green, would you like to come down, please? 656 00:37:21,200 --> 00:37:23,000 APPLAUSE 657 00:37:26,160 --> 00:37:30,240 Your name is? Ailish. Ailish, OK, great. 658 00:37:30,240 --> 00:37:33,440 Obviously you've seen a lot of aluminium before, haven't you? 659 00:37:33,440 --> 00:37:35,920 It's very cheap now because now we have worked out 660 00:37:35,920 --> 00:37:38,520 how to extract it from the ores, but initially, 661 00:37:38,520 --> 00:37:42,360 it was incredibly difficult and that made it incredibly expensive. 662 00:37:42,360 --> 00:37:46,200 In fact, so valuable and so strange that this chap, 663 00:37:46,200 --> 00:37:48,040 this is Napoleon III, 664 00:37:48,040 --> 00:37:51,120 he had a whole cutlery set made from aluminium. 665 00:37:51,120 --> 00:37:54,160 I think we have some aluminium utensils here 666 00:37:54,160 --> 00:37:56,600 so you have a look at these. What do you think? 667 00:37:56,600 --> 00:37:58,960 Very light. They are very light, aren't they? 668 00:37:58,960 --> 00:38:00,640 This was the remarkable thing. 669 00:38:00,640 --> 00:38:03,640 With Napoleon's cutlery set, he had his cutlery, 670 00:38:03,640 --> 00:38:06,480 and it was so valuable that if he had a huge feast, 671 00:38:06,480 --> 00:38:10,640 he would give his most honoured guests the aluminium cutlery 672 00:38:10,640 --> 00:38:13,080 and all the rest had to make do with gold. 673 00:38:13,080 --> 00:38:14,920 OK, it seems strange to us now 674 00:38:14,920 --> 00:38:17,320 because we do know how to extract aluminium 675 00:38:17,320 --> 00:38:20,720 and it is incredibly abundant and we can find loads of it around 676 00:38:20,720 --> 00:38:22,840 but it was very difficult to get it out. 677 00:38:22,840 --> 00:38:25,440 Can I just say, it does feel very light indeed. 678 00:38:25,440 --> 00:38:27,880 That is one of the remarkable properties. 679 00:38:27,880 --> 00:38:30,880 It isn't actually the lightest metal that's known. 680 00:38:30,880 --> 00:38:34,720 Do you know what the lightest metal is? Lithium. 681 00:38:34,720 --> 00:38:38,480 Oh, yes, you're quite right. It is lithium. Give us a wave, lithium! 682 00:38:38,480 --> 00:38:41,880 Lithium is in fact a metal and it is incredibly light. 683 00:38:41,880 --> 00:38:46,200 We have made the world's first lithium spoon, 684 00:38:46,200 --> 00:38:49,640 which is very exciting. Here it is. 685 00:38:49,640 --> 00:38:52,960 This is our special RI spoon. 686 00:38:54,920 --> 00:38:58,160 Isn't that beautiful? Would you like to feel this? 687 00:38:58,160 --> 00:39:01,800 It's really light. It really is. It's amazingly light. 688 00:39:01,800 --> 00:39:05,440 It feels almost like plastic but it is solid metal. 689 00:39:05,440 --> 00:39:07,800 It is quite remarkable, don't you think? 690 00:39:07,800 --> 00:39:12,480 This is my dinner, I think. 691 00:39:12,480 --> 00:39:17,560 Some soup. Of course, cutlery sinks in it, 692 00:39:17,560 --> 00:39:22,160 but would you just drop it in and step back? 693 00:39:22,160 --> 00:39:23,920 Look at that? First of all, 694 00:39:23,920 --> 00:39:26,960 it is incredibly light and it's floating on the surface, 695 00:39:26,960 --> 00:39:28,440 but it's also reacting. 696 00:39:28,440 --> 00:39:31,880 I'm going to fish that out. It's very reactive indeed. 697 00:39:31,880 --> 00:39:35,440 I don't think lithium spoons are going to catch on at all, do you? 698 00:39:35,440 --> 00:39:38,480 This is because it's just too reactive. Too explosive. 699 00:39:38,480 --> 00:39:41,120 Exactly, thank you very much indeed. 700 00:39:41,120 --> 00:39:43,680 APPLAUSE 701 00:39:46,280 --> 00:39:49,320 A bit of coughing there just from the reaction 702 00:39:49,320 --> 00:39:51,960 as the lithium combines with the oxygen. 703 00:39:51,960 --> 00:39:54,640 It's reacting with the water vapour. 704 00:39:54,640 --> 00:39:57,760 COUGHING 705 00:39:57,760 --> 00:40:03,720 Yes, yes. Thank you. The lithium there, it floats on the surface. 706 00:40:03,720 --> 00:40:08,640 It is incredibly light but it's incredibly reactive as well. 707 00:40:08,640 --> 00:40:11,880 That may be the world's first lithium spoon 708 00:40:11,880 --> 00:40:16,360 but I think it's safe to say it's also going to be the world's last. 709 00:40:16,360 --> 00:40:20,920 It does show how reactive lithium is and maybe be can use this element 710 00:40:20,920 --> 00:40:23,800 to prepare new elements, and we can indeed. 711 00:40:23,800 --> 00:40:30,000 We have a reaction here to generate a new element from silicon dioxide. 712 00:40:30,000 --> 00:40:34,520 Does anyone know where we find silicon dioxide? 713 00:40:34,520 --> 00:40:36,920 Any ideas, right at the back? 714 00:40:36,920 --> 00:40:39,400 In sand, you're quite right. 715 00:40:39,400 --> 00:40:43,120 We find silicon dioxide, it is sand. 716 00:40:45,000 --> 00:40:48,240 We've got some lithium in here and some sand. 717 00:40:48,240 --> 00:40:51,880 We've mixed the two together, little lithium pelts and some sand, 718 00:40:51,880 --> 00:40:56,720 and I'm going to heat this up at the moment and see what happens. 719 00:40:56,720 --> 00:40:59,160 This is lithium with silicon dioxide 720 00:40:59,160 --> 00:41:02,440 and the silicon dioxide is a mineral, it's just sand. 721 00:41:02,440 --> 00:41:04,880 Quartz is the same stuff, silicon dioxide, 722 00:41:04,880 --> 00:41:08,960 so sand is smashed up pieces of quartz. 723 00:41:08,960 --> 00:41:12,000 I'm hoping that we should see a reaction take place 724 00:41:12,000 --> 00:41:14,640 and there we are. 725 00:41:14,640 --> 00:41:18,000 This is a very violent reaction again 726 00:41:18,000 --> 00:41:21,960 and this is as the lithium is stealing the oxygen away 727 00:41:21,960 --> 00:41:25,160 from the silicon dioxide that makes up the sand. 728 00:41:27,040 --> 00:41:31,320 Anyone have a guess at what we're going to make? Silicon, very good. 729 00:41:31,320 --> 00:41:35,560 We take the oxygen away from the silicon dioxide 730 00:41:35,560 --> 00:41:38,760 and we end up with silicon. 731 00:41:38,760 --> 00:41:43,440 Remarkably, this is a single crystal 732 00:41:43,440 --> 00:41:47,160 of a very purified silicon. 733 00:41:47,160 --> 00:41:50,000 It's very valuable and very precious 734 00:41:50,000 --> 00:41:53,040 and I need to put on some special gloves for this. 735 00:41:56,200 --> 00:42:00,440 It's hard, it's very solid. 736 00:42:00,440 --> 00:42:04,760 It's sort of like a metal and it's incredibly heavy. 737 00:42:04,760 --> 00:42:08,880 Actually, I can hardly lift this thing up, 738 00:42:08,880 --> 00:42:11,960 but it's grown in this very special way here. 739 00:42:11,960 --> 00:42:13,840 This is one crystal of silicon 740 00:42:13,840 --> 00:42:17,200 but it has a seam running all the way along the top here. 741 00:42:17,200 --> 00:42:21,160 This just proves that it is in fact one crystal. 742 00:42:21,160 --> 00:42:23,400 Why do people grow these? 743 00:42:23,400 --> 00:42:26,960 They grow them from the molten silicon. 744 00:42:26,960 --> 00:42:29,400 They would keep purifying it, heating it 745 00:42:29,400 --> 00:42:33,240 and allowing it to cool into this rather strange-looking shape. 746 00:42:33,240 --> 00:42:36,160 They do this because they're trying to make these, 747 00:42:36,160 --> 00:42:40,480 and this is a silicon wafer. 748 00:42:40,480 --> 00:42:44,400 It's just a sheet of silicon, just a slice from this, 749 00:42:44,400 --> 00:42:49,280 and these are used to make silicon chips. 750 00:42:49,280 --> 00:42:53,040 This is the same slice of silicon 751 00:42:53,040 --> 00:42:59,240 and then they're etching in and adding other reagents to this, 752 00:42:59,240 --> 00:43:02,240 gradually building up the silicon chips that we have 753 00:43:02,240 --> 00:43:07,400 in our mobile phones and in our computers. 754 00:43:10,080 --> 00:43:13,400 A fantastic use for this element, silicon. 755 00:43:13,400 --> 00:43:17,000 The element we extract from sand. 756 00:43:17,000 --> 00:43:20,360 Chemists are always finding new uses for the elements. 757 00:43:20,360 --> 00:43:23,640 Even though this has been known for well over 100 years, 758 00:43:23,640 --> 00:43:27,680 it is only relatively recently that we have found out 759 00:43:27,680 --> 00:43:30,760 how to use this element to make silicon chips. 760 00:43:30,760 --> 00:43:31,960 So far in the lecture, 761 00:43:31,960 --> 00:43:35,400 we swapped elements around to make different useful materials. 762 00:43:35,400 --> 00:43:38,480 We've stolen oxygen from iron oxide to make iron, 763 00:43:38,480 --> 00:43:40,080 and we've stolen it from sand. 764 00:43:40,080 --> 00:43:43,400 We've even rearranged the structures of carbon 765 00:43:43,400 --> 00:43:45,600 to turn graphite into diamond. 766 00:43:45,600 --> 00:43:51,040 What we still haven't done is turn one element into another. 767 00:43:51,040 --> 00:43:53,680 That's what the alchemists were trying to do, 768 00:43:53,680 --> 00:43:56,320 to turn lead into gold. Is this possible? 769 00:43:56,320 --> 00:43:58,760 Can we turn one element into another? 770 00:43:58,760 --> 00:44:03,240 Yes, this is the process of radioactivity, 771 00:44:03,240 --> 00:44:08,040 and this occurs deep in the Earth and indeed all around us. 772 00:44:08,040 --> 00:44:11,280 Can we have our periodic table up, please? 773 00:44:11,280 --> 00:44:14,560 Those of you, you elements who are radioactive, 774 00:44:14,560 --> 00:44:16,640 I'd like you to stand up, please. 775 00:44:16,640 --> 00:44:20,680 All the radioactive elements. That's all of this front row here. 776 00:44:20,680 --> 00:44:22,320 Yes, you're all radioactive. 777 00:44:22,320 --> 00:44:25,080 Bismuth, we're not sure about you, you're unknown, 778 00:44:25,080 --> 00:44:27,000 but actually you're so radioactive, 779 00:44:27,000 --> 00:44:29,040 you're no longer who you thought you were. 780 00:44:29,040 --> 00:44:31,640 You'd better sit down again. What does that mean? 781 00:44:31,640 --> 00:44:33,320 Why do you have to sit down again? 782 00:44:33,320 --> 00:44:36,080 It's because during radioactive decay, 783 00:44:36,080 --> 00:44:40,160 an element changes into another element. 784 00:44:40,160 --> 00:44:42,920 If we have cards down for a moment, please? 785 00:44:42,920 --> 00:44:46,600 Remember, what makes an element unique 786 00:44:46,600 --> 00:44:49,720 is the heart of the atom itself. 787 00:44:49,720 --> 00:44:54,040 That's the number of protons that it has within it. 788 00:44:54,040 --> 00:44:57,520 This represents what's inside an atom. 789 00:44:57,520 --> 00:45:01,600 This is its nucleus, and we have to count the number of the red spheres, 790 00:45:01,600 --> 00:45:03,360 these represent the protons, 791 00:45:03,360 --> 00:45:05,600 to work out what element this is. 792 00:45:05,600 --> 00:45:08,040 In fact, this is the element uranium. 793 00:45:08,040 --> 00:45:13,480 The thing about uranium is - oops - it's unstable, 794 00:45:13,480 --> 00:45:15,520 and bits drop off. 795 00:45:15,520 --> 00:45:17,600 The nucleus here just gets so large 796 00:45:17,600 --> 00:45:21,840 that it's very difficult for all these things to stay together 797 00:45:21,840 --> 00:45:25,120 and, yes, bits do drop off and when they drop off, 798 00:45:25,120 --> 00:45:27,440 it's changed into different element. 799 00:45:27,440 --> 00:45:31,760 It's the number of the red protons that define an element, 800 00:45:31,760 --> 00:45:33,040 so if we lose two, 801 00:45:33,040 --> 00:45:37,080 it's no longer what we thought it was to start off with. 802 00:45:37,080 --> 00:45:40,320 Can we find uranium in our periodic table. Where's uranium? 803 00:45:40,320 --> 00:45:44,800 Would you like to stand up? 804 00:45:44,800 --> 00:45:49,040 Uranium, you are radioactive, and bits do drop off. 805 00:45:49,040 --> 00:45:51,720 Quite slowly, don't worry, we won't notice. 806 00:45:51,720 --> 00:45:55,040 But actually when it does happen, when it does fall off, 807 00:45:55,040 --> 00:45:57,080 you change into a different element 808 00:45:57,080 --> 00:45:59,200 and you move a couple of spaces along. 809 00:45:59,200 --> 00:46:02,480 You become thorium, so maybe you should move over to thorium. 810 00:46:02,480 --> 00:46:07,480 Better put your card down because you're not "U" any more. Get it? 811 00:46:07,480 --> 00:46:10,400 You're no longer you, you're actually thorium. 812 00:46:10,400 --> 00:46:13,880 You'd better go over there, you are on thorium's space now. 813 00:46:13,880 --> 00:46:18,520 Actually, both thorium and uranium have also decayed, 814 00:46:18,520 --> 00:46:22,600 and if you decay now, you're going to become the element radon. 815 00:46:22,600 --> 00:46:25,960 You're also radioactive, I'm afraid, so if you decay, 816 00:46:25,960 --> 00:46:29,520 you lose a couple of protons in an alpha particle. 817 00:46:29,520 --> 00:46:33,120 You're not radon any more, you've become polonium. 818 00:46:33,120 --> 00:46:34,920 Can we see this in action? 819 00:46:34,920 --> 00:46:38,640 We can, using this apparatus here. 820 00:46:38,640 --> 00:46:42,160 This is known as a cloud chamber. 821 00:46:42,160 --> 00:46:49,920 The tank that we see here contains an atmosphere of alcohol vapour 822 00:46:49,920 --> 00:46:52,480 and it's got a lot of vapour in there 823 00:46:52,480 --> 00:46:55,680 and it's actually trying to form little droplets. 824 00:46:55,680 --> 00:46:57,520 There's a temperature gradient. 825 00:46:57,520 --> 00:47:00,720 There's a little heating wire at the top and it's cooled down 826 00:47:00,720 --> 00:47:03,160 from underneath, so it's gradually freezing. 827 00:47:03,160 --> 00:47:07,520 It wants to form droplets but actually it's much easier 828 00:47:07,520 --> 00:47:09,720 if there's something there to help it. 829 00:47:09,720 --> 00:47:12,720 Any charged particles can cause this. 830 00:47:12,720 --> 00:47:16,000 All the tracks that you can see now, 831 00:47:16,000 --> 00:47:18,840 all these little wispy white trails, 832 00:47:18,840 --> 00:47:24,040 are actually particles of radiation. 833 00:47:24,040 --> 00:47:28,400 This is natural radiation just in the air around us. 834 00:47:28,400 --> 00:47:32,120 We don't tend to think of radioactivity as being very natural, 835 00:47:32,120 --> 00:47:34,880 but of course, we're all weakly radioactive 836 00:47:34,880 --> 00:47:37,520 because of some of the radioactive elements in us. 837 00:47:37,520 --> 00:47:42,880 Here, we can see radiation in action here just in the air around us. 838 00:47:42,880 --> 00:47:48,640 I'm going to introduce into this a sample of a radioactive element 839 00:47:48,640 --> 00:47:52,120 called americium. 840 00:47:52,120 --> 00:47:57,440 Look at that. You can see the tracks forming here. 841 00:48:00,680 --> 00:48:06,640 Each little track that we see is the result of a charged particle 842 00:48:06,640 --> 00:48:12,280 being emitted from the element americium 843 00:48:12,280 --> 00:48:16,960 and the particles emitted are alpha particles. 844 00:48:16,960 --> 00:48:21,800 The alpha particle is two protons, two neutrons, 845 00:48:21,800 --> 00:48:26,040 and actually that is the heart of an atom of helium. 846 00:48:26,040 --> 00:48:31,600 What we're actually seeing here is the birth of helium atoms, 847 00:48:31,600 --> 00:48:37,440 which I think is quite remarkable. I'll just put this away. 848 00:48:37,440 --> 00:48:42,120 It is possible then to change one atom into another. 849 00:48:42,120 --> 00:48:45,720 Nature seems to do this, but can we? 850 00:48:45,720 --> 00:48:47,720 Actually, it is possible, 851 00:48:47,720 --> 00:48:51,480 and one of the first people to generate lots of different atoms 852 00:48:51,480 --> 00:48:54,520 was this chap here, Glenn Seaborg. 853 00:48:54,520 --> 00:48:58,560 In fact, he even has an element named after him. 854 00:48:58,560 --> 00:49:00,800 Where's seaborgium? There we are, 855 00:49:00,800 --> 00:49:03,440 right in the middle of the periodic table. 856 00:49:03,440 --> 00:49:08,400 In 1980, Seaborg did an amazing experiment. 857 00:49:08,400 --> 00:49:13,200 He took bismuth and he turned it into gold. 858 00:49:13,200 --> 00:49:16,520 This is what the alchemists had been dreaming of. 859 00:49:16,520 --> 00:49:18,520 He changed one element into gold. 860 00:49:18,520 --> 00:49:20,240 What he did was take bismuth - 861 00:49:20,240 --> 00:49:23,400 can we have our periodic table up for a second, please? 862 00:49:23,400 --> 00:49:28,240 He took the element bismuth and he fired atoms of carbon and neon 863 00:49:28,240 --> 00:49:32,440 at this and it knocked out a number of protons 864 00:49:32,440 --> 00:49:35,280 until we ended up with gold. 865 00:49:35,280 --> 00:49:39,040 Unfortunately, he only ended up with the few thousand atoms 866 00:49:39,040 --> 00:49:41,440 and this is not enough to get him rich. 867 00:49:41,440 --> 00:49:45,000 It was a very expensive experiment, took a lot of money to get this 868 00:49:45,000 --> 00:49:49,560 and all he made was a few atoms, but it is possible to do it. 869 00:49:49,560 --> 00:49:53,400 Radioactivity is a natural process but it can also be brought about 870 00:49:53,400 --> 00:49:55,920 by firing one atom at another, 871 00:49:55,920 --> 00:49:59,880 and changing it and creating new, heavier elements 872 00:49:59,880 --> 00:50:01,720 or even to make gold. 873 00:50:01,720 --> 00:50:03,520 Do we even want to make gold? 874 00:50:03,520 --> 00:50:06,160 Are there other things that fascinated the alchemists 875 00:50:06,160 --> 00:50:09,480 which modern scientists have taken one step further? 876 00:50:09,480 --> 00:50:12,120 This is another naturally occurring rock 877 00:50:12,120 --> 00:50:15,160 that has really quite remarkable properties. 878 00:50:15,160 --> 00:50:18,640 This one amazed the early alchemists. 879 00:50:18,640 --> 00:50:20,440 I'll show you why. 880 00:50:20,440 --> 00:50:23,920 Over here, our audience members have some paper clips. 881 00:50:23,920 --> 00:50:26,720 Have you got some paper clips? 882 00:50:26,720 --> 00:50:31,200 I'd like you to put your paper clips onto here, just onto the rock. 883 00:50:32,800 --> 00:50:35,800 They should stick by themselves. 884 00:50:35,800 --> 00:50:39,960 It's not a surprise to us because we've all seen magnets before, 885 00:50:39,960 --> 00:50:44,120 but just imagine if you were the first person to ever see a magnet. 886 00:50:44,120 --> 00:50:46,840 I have a book here from the 1530s 887 00:50:46,840 --> 00:50:51,480 that describes this magnetic rock, this lodestone. 888 00:50:51,480 --> 00:50:54,320 They really did find it quite remarkable. 889 00:50:54,320 --> 00:50:56,960 This here shows this magnetic rock. 890 00:50:56,960 --> 00:51:02,720 There's a ship sailing past a mountain that's supposedly made 891 00:51:02,720 --> 00:51:06,440 of this lodestone, this magnetic ore. 892 00:51:06,440 --> 00:51:10,080 You can see here, these are the nails from the ship. 893 00:51:10,080 --> 00:51:14,280 They've supposedly been sucked out of the ship, so this is 894 00:51:14,280 --> 00:51:18,520 a sort of warning that there's this incredibly strange magical material 895 00:51:18,520 --> 00:51:22,040 with these amazing properties which would suck the nails 896 00:51:22,040 --> 00:51:24,680 out of your ship and you'd be shipwrecked. 897 00:51:24,680 --> 00:51:28,880 There's a warning for you. OK, thank you. 898 00:51:28,880 --> 00:51:35,000 Nowadays, scientists have learned how to make even stronger magnets 899 00:51:35,000 --> 00:51:38,240 from the elements, and if we just have our periodic table up again, 900 00:51:38,240 --> 00:51:45,720 some of the strongest magnets now made use the element neodymium. 901 00:51:45,720 --> 00:51:49,600 Give us a wave, up there, very good. 902 00:51:49,600 --> 00:51:54,040 The strongest magnets in the world are made with neodymium. 903 00:51:54,040 --> 00:51:56,320 This element was discovered in the 1880s, 904 00:51:56,320 --> 00:52:00,960 but it was over 100 years later that scientists learnt how to use 905 00:52:00,960 --> 00:52:03,800 this element to create these magnets. 906 00:52:03,800 --> 00:52:06,080 Thank you very much, periodic table. 907 00:52:06,080 --> 00:52:08,120 I have a couple of these magnets here 908 00:52:08,120 --> 00:52:10,840 and they really are very strong indeed. 909 00:52:10,840 --> 00:52:13,600 These are little neodymium magnets. 910 00:52:13,600 --> 00:52:16,640 Here we are, just try to pull these apart? 911 00:52:16,640 --> 00:52:19,240 I can't. Are they stuck together? 912 00:52:19,240 --> 00:52:22,480 No, they're not stuck together. Try again. 913 00:52:22,480 --> 00:52:26,120 Give them to your neighbour, see if he can get them? 914 00:52:26,120 --> 00:52:28,400 Can you pull those apart? No. 915 00:52:28,400 --> 00:52:31,240 I promise you they're not stuck together. 916 00:52:31,240 --> 00:52:36,120 I could probably slide them or something if I push. Look at that. 917 00:52:36,120 --> 00:52:39,360 They're very strong magnets indeed. 918 00:52:39,360 --> 00:52:43,640 Even though the element neodymium has been known for over 100 years, 919 00:52:43,640 --> 00:52:47,720 these magnets have only recently been developed. 920 00:52:47,720 --> 00:52:49,760 Now, these really are quite strong 921 00:52:49,760 --> 00:52:54,920 and I think to show just how strong these are, I need another volunteer. 922 00:52:54,920 --> 00:52:58,480 I think we should have one from this side. 923 00:52:58,480 --> 00:53:02,480 Would you like to come down to the front, please? 924 00:53:02,480 --> 00:53:05,760 APPLAUSE 925 00:53:05,760 --> 00:53:09,600 OK, very good. Are you feeling strong? You are, that's good. 926 00:53:09,600 --> 00:53:12,240 Tell us your name, please. Marie. Marie. 927 00:53:12,240 --> 00:53:15,960 We're just going to bring down this rig here. 928 00:53:15,960 --> 00:53:19,440 We're going to suspend you from the ceiling 929 00:53:19,440 --> 00:53:23,240 using this little magnet here. That's the only magnet. 930 00:53:23,240 --> 00:53:26,080 This is a block of iron. It's not magnetic. 931 00:53:26,080 --> 00:53:27,920 I can show that with a paper clip, 932 00:53:27,920 --> 00:53:30,920 just holding the paper clip, it stays on it 933 00:53:30,920 --> 00:53:32,760 but it's not attracted to it. 934 00:53:32,760 --> 00:53:34,120 This is our magnet. 935 00:53:34,120 --> 00:53:37,680 I'm not going to put the paper clip on this, I'd never get it off again. 936 00:53:37,680 --> 00:53:39,920 If you'd like to come over here, please. 937 00:53:39,920 --> 00:53:43,360 I just need to very carefully put this in the middle. Perfect. 938 00:53:43,360 --> 00:53:47,000 Just clip this on as well. 939 00:53:47,000 --> 00:53:51,480 OK, so you're feeling strong? 940 00:53:51,480 --> 00:53:55,440 If you just hold on to here. That's it. 941 00:53:55,440 --> 00:53:58,040 Can you just raise up the winch then, please? 942 00:53:58,040 --> 00:54:01,840 Hold on strong, hold on tightly and we'll just see if we can lift you 943 00:54:01,840 --> 00:54:04,640 off the ground so you need to hold on very tightly. 944 00:54:04,640 --> 00:54:06,720 Might need to move forward a little bit. 945 00:54:06,720 --> 00:54:09,160 Keep holding on and just watch the feet. 946 00:54:09,160 --> 00:54:10,960 There we are, look at that! 947 00:54:10,960 --> 00:54:14,920 You are now suspended from the ceiling. That's fantastic! 948 00:54:14,920 --> 00:54:17,280 APPLAUSE 949 00:54:19,800 --> 00:54:22,160 It really is pretty strong magnets there. 950 00:54:22,160 --> 00:54:24,160 We can actually hang from them. 951 00:54:24,160 --> 00:54:27,640 It's just using the power of these new magnets 952 00:54:27,640 --> 00:54:30,880 but these are incredibly useful and they find uses for instance 953 00:54:30,880 --> 00:54:36,040 in turbines, but are also used in electric cars and so on as well. 954 00:54:36,040 --> 00:54:39,200 These new materials - very, very useful. 955 00:54:39,200 --> 00:54:43,320 We can create even more amazing materials using the elements. 956 00:54:43,320 --> 00:54:46,160 Can we just have our periodic table up for a moment? 957 00:54:46,160 --> 00:54:48,520 We were using magnets there to suspend 958 00:54:48,520 --> 00:54:50,920 and these were the neodymium magnets, 959 00:54:50,920 --> 00:54:54,040 but this, we're going to use some superconductors 960 00:54:54,040 --> 00:54:58,280 and the superconductors are made from the elements yttrium, 961 00:54:58,280 --> 00:55:01,360 just here. Give us a wave, yttrium. 962 00:55:01,360 --> 00:55:05,840 And from barium, so give us a wave, barium. Very good. 963 00:55:05,840 --> 00:55:09,400 And copper. OK, there's copper, 964 00:55:09,400 --> 00:55:12,520 and oxygen at the top there. 965 00:55:12,520 --> 00:55:17,280 Put you four elements together and we get these amazing materials - 966 00:55:17,280 --> 00:55:19,440 high-temperature superconductors. 967 00:55:19,440 --> 00:55:23,640 This is called a Mobius strip. It's a rather strange looking thing. 968 00:55:23,640 --> 00:55:27,680 How many sides has this got? Two. Well, you'd think so. 969 00:55:27,680 --> 00:55:31,600 Actually, if you start here and you keep on going round, 970 00:55:31,600 --> 00:55:34,280 you actually come back underneath. 971 00:55:34,280 --> 00:55:37,920 If you keep going round, you come back where you started from. 972 00:55:37,920 --> 00:55:40,800 It actually has one side, this mathematical shape, 973 00:55:40,800 --> 00:55:42,600 which is very unusual. 974 00:55:42,600 --> 00:55:46,440 I can show you this using our little superconductor. 975 00:55:46,440 --> 00:55:50,680 This Mobius strip is covered with these neodymium magnets, 976 00:55:50,680 --> 00:55:54,160 these very strong magnets. We've got a superconductor here 977 00:55:54,160 --> 00:55:56,760 and this is the superconductor 978 00:55:56,760 --> 00:56:01,680 that's made from the barium, the yttrium, the copper and the oxygen. 979 00:56:01,680 --> 00:56:05,280 This is the ceramic there. This is this disc in the centre. 980 00:56:05,280 --> 00:56:07,760 We are cooling it with liquid nitrogen 981 00:56:07,760 --> 00:56:11,440 in this little holding tray on the top. 982 00:56:11,440 --> 00:56:13,000 It levitates quite nicely. 983 00:56:18,280 --> 00:56:22,760 There we are, it's come back to where it was. 984 00:56:22,760 --> 00:56:26,760 Now it's actually hanging underneath this strip, 985 00:56:26,760 --> 00:56:28,280 but it needs to be cooled down 986 00:56:28,280 --> 00:56:30,560 so we are cooling it with liquid nitrogen. 987 00:56:30,560 --> 00:56:34,440 That's in order to enable these superconductors to work. 988 00:56:34,440 --> 00:56:36,840 They only work at these very low temperatures, 989 00:56:36,840 --> 00:56:40,480 so eventually it's going to warm up and it will fall off the track 990 00:56:40,480 --> 00:56:43,600 so you need to catch it when it does fall. 991 00:56:43,600 --> 00:56:45,920 You're meant to catch it! 992 00:56:45,920 --> 00:56:49,200 Just pass it to me straight away, thank you. That's lovely. 993 00:56:51,040 --> 00:56:54,480 Thank you very much. Thank you for all your help there. 994 00:56:54,480 --> 00:56:56,760 APPLAUSE 995 00:57:04,000 --> 00:57:07,680 Really quite remarkable properties then of this ceramic 996 00:57:07,680 --> 00:57:11,840 made out of the elements barium, yttrium, copper and oxygen. 997 00:57:11,840 --> 00:57:15,000 We've come a long way since the days of the alchemists 998 00:57:15,000 --> 00:57:20,000 when the whole world could be made from air, water, earth and fire. 999 00:57:20,000 --> 00:57:22,520 I hope you've enjoyed our quest to discover 1000 00:57:22,520 --> 00:57:25,160 what's really making up the world around us. 1001 00:57:25,160 --> 00:57:28,280 If you remember one thing from these lectures, 1002 00:57:28,280 --> 00:57:30,720 it's that the work of the chemist is not complete. 1003 00:57:30,720 --> 00:57:34,200 New combinations are being discovered all the time 1004 00:57:34,200 --> 00:57:37,960 and nobody knows what exciting properties they may have. 1005 00:57:37,960 --> 00:57:40,760 I'd like everyone to pick up your cards one last time 1006 00:57:40,760 --> 00:57:42,960 and have a look at your card. 1007 00:57:42,960 --> 00:57:47,040 Just remember what element you've got, and I want you to go home 1008 00:57:47,040 --> 00:57:49,120 and research about your element 1009 00:57:49,120 --> 00:57:52,200 and think what uses can we put this element to, 1010 00:57:52,200 --> 00:57:55,640 and what new possibilities could there be? Who knows? 1011 00:57:55,640 --> 00:57:59,120 You may be able to solve some of the challenges of the future 1012 00:57:59,120 --> 00:58:03,120 and maybe even make something more valuable than gold. 1013 00:58:03,120 --> 00:58:05,680 Thank you and goodnight. 1014 00:58:05,680 --> 00:58:06,560 APPLAUSE 1015 00:58:09,840 --> 00:58:12,760 Subtitles by Red Bee Media Ltd