0:00:02 > 0:00:05Gold. This is what alchemists' dreams were made of.
0:00:05 > 0:00:09The medieval thinkers spent their lives trying to find a way
0:00:09 > 0:00:13to turn cheap metals, such as this lead, into gold.
0:00:15 > 0:00:18Success would bring them fame and infinite fortune,
0:00:18 > 0:00:21but is such magic even possible?
0:00:21 > 0:00:24Join us in the search for the philosopher's stone.
0:00:45 > 0:00:48APPLAUSE
0:01:01 > 0:01:05The alchemists were obsessed with the idea of producing
0:01:05 > 0:01:06a philosopher's stone.
0:01:06 > 0:01:11A magical rock or powder that could turn metals into gold.
0:01:11 > 0:01:15There are even stories of espionage, kidnap and even murder
0:01:15 > 0:01:18in a bid to steal the secret of the stone.
0:01:18 > 0:01:20But what about the gold I just made?
0:01:22 > 0:01:24Well, I'm afraid we cheated.
0:01:24 > 0:01:27I'm not an alchemist. My name is Dr Peter Wothers
0:01:27 > 0:01:31and I'm a chemist from the University of Cambridge.
0:01:31 > 0:01:33I did start with lead.
0:01:33 > 0:01:36It was a specially prepared form of lead that reacts
0:01:36 > 0:01:41with the oxygen from the air to give this beautiful lead oxide.
0:01:41 > 0:01:43This yellowy orange compound here.
0:01:43 > 0:01:46So we did cheat here.
0:01:46 > 0:01:48And my philosopher's stone, well,
0:01:48 > 0:01:52it was just a hot coal which started this reaction.
0:01:52 > 0:01:56Some alchemists used this reaction to try to convince people
0:01:56 > 0:02:00that they could make gold. But is such a feat even possible?
0:02:00 > 0:02:03In the last of this year's Royal Institution Christmas lectures,
0:02:03 > 0:02:05I hope to find out.
0:02:05 > 0:02:07In the previous lectures,
0:02:07 > 0:02:10we've looked at the elements in the air, and water, and now we are
0:02:10 > 0:02:13going to look at the elements in the earth and how we can extract them.
0:02:13 > 0:02:17How we can use them and whether we can turn one into another.
0:02:17 > 0:02:20To help me, I have a giant periodic table made up
0:02:20 > 0:02:24of members from the audience here at the Royal Institution.
0:02:24 > 0:02:28Let's just look at the elements we have already talked about.
0:02:28 > 0:02:30We have lead, can you stand up, please, lead? Thank you.
0:02:30 > 0:02:32We were looking at you
0:02:32 > 0:02:34and you were reacting with the oxygen from the air.
0:02:34 > 0:02:37Can you stand up please, oxygen? OK.
0:02:37 > 0:02:42This is how we normally find our metals in the earth.
0:02:42 > 0:02:44We don't find them lying around,
0:02:44 > 0:02:47they are normally combined with the oxygen from the air.
0:02:47 > 0:02:51Or maybe sulphur, or occasionally other metals. Thank you very much.
0:02:51 > 0:02:54If we put our periodic tables down now, please.
0:02:54 > 0:02:58But occasionally, we can find metals just lying around.
0:02:58 > 0:03:02The classic case is gold. Where are you, gold?
0:03:02 > 0:03:08You are so special because sometimes you can be found just lying around.
0:03:08 > 0:03:14In fact, here's a piece of you here. This is a gold nugget.
0:03:14 > 0:03:16Thank you, periodic table, at ease.
0:03:16 > 0:03:20This is pure gold. And it can be found like this in nature.
0:03:20 > 0:03:23In fact, this is how it is normally found.
0:03:23 > 0:03:27Now the remarkable thing about gold is that it doesn't change over time.
0:03:27 > 0:03:31So you could leave it for tens, hundreds, even thousands
0:03:31 > 0:03:36of years and it'll still have this beautiful appearance.
0:03:36 > 0:03:39I've got a very old piece of gold to show you now.
0:03:39 > 0:03:44Would you please welcome, from the Museum of London, Meriel Jeater.
0:03:44 > 0:03:46APPLAUSE
0:03:51 > 0:03:55I gather that this is a piece of local gold, is that right?
0:03:55 > 0:03:59Exactly, yes. It was found in London, in Cannon Street in 1976.
0:03:59 > 0:04:03- It's actually a Roman gold and emerald necklace.- That's beautiful.
0:04:03 > 0:04:06This is pure gold wire running through these emeralds?
0:04:06 > 0:04:10- That's right, yes.- And you say this is from the early Roman times?
0:04:10 > 0:04:14- This is how old?- Nearly 2,000 years old, yes.- 2,000 years old.
0:04:14 > 0:04:16Has this been heavily restored?
0:04:16 > 0:04:19It's been given a bit of a clean to get the mud off.
0:04:19 > 0:04:23- Just the mud off and the gold itself was looking just like this?- Exactly.
0:04:23 > 0:04:26- That's why it's so wonderful for archaeologists.- Exactly.
0:04:26 > 0:04:29For me as a chemist, I think it's incredible that you can find
0:04:29 > 0:04:31gold in this state and it doesn't tarnish over time.
0:04:31 > 0:04:33It doesn't combine with oxygen or water or anything.
0:04:33 > 0:04:35This is how you find it.
0:04:35 > 0:04:37You can see that clearly it was highly prized
0:04:37 > 0:04:40and I think maybe you should take it back to the museum.
0:04:40 > 0:04:42- Thank you very much.- Pleasure. - Big round of applause, please.
0:04:42 > 0:04:44APPLAUSE
0:04:47 > 0:04:51This has lasted so well because it was so highly prized,
0:04:51 > 0:04:55so valued there but also because it didn't change over time.
0:04:55 > 0:04:58But, of course, we have a saying about the value of gold.
0:04:58 > 0:05:02Sometimes people are told, "You're worth your weight in gold."
0:05:02 > 0:05:05- Have you ever been told you're worth your weight in gold?- Yeah.
0:05:05 > 0:05:07Oh, you have! Oh, good. Who told you that?
0:05:07 > 0:05:09- I can't remember.- Probably a parent.
0:05:09 > 0:05:13Maybe we should ask gold. Where's gold sitting? Are you gold, yes?
0:05:13 > 0:05:17Have you been told that you're worth your weight in gold before?
0:05:17 > 0:05:20- I think my parents... - They've told you this, have they?
0:05:20 > 0:05:24I think we should see just how much gold that would be.
0:05:24 > 0:05:26Would you like to come down to the front, please?
0:05:26 > 0:05:29APPLAUSE
0:05:30 > 0:05:32Would you like to face the front here.
0:05:32 > 0:05:34- Would you like to tell everyone your name?- Emma.
0:05:34 > 0:05:35Take a seat on here.
0:05:35 > 0:05:38If you just carefully sit down on there. That's beautiful, lovely job.
0:05:38 > 0:05:41OK, right, are you sitting comfortably?
0:05:41 > 0:05:44- Yep.- Then we'll begin. This is where I get very excited.
0:05:44 > 0:05:51This is all real gold. And it's pretty good stuff, actually.
0:05:51 > 0:05:54Have you ever held a big block of gold before?
0:05:54 > 0:05:56- No.- No. Well, have a feel of this.
0:05:57 > 0:06:00That is pretty exciting, isn't it? Would you like to feel this as well?
0:06:00 > 0:06:02I'm afraid I can't let everybody have...
0:06:02 > 0:06:04I know, it's amazing, isn't it?
0:06:04 > 0:06:09This is actually about the same as six large bottles of fizzy pop.
0:06:09 > 0:06:12I'm just going to put this on here.
0:06:14 > 0:06:17OK, I think you need more than that. Let's keep going.
0:06:17 > 0:06:20Let's put this one on. It really is pretty good stuff, this.
0:06:22 > 0:06:25This is 24ct pure gold.
0:06:25 > 0:06:27And this one here.
0:06:28 > 0:06:30More. More still.
0:06:33 > 0:06:37Not quite. No. OK, let's try this one.
0:06:43 > 0:06:45I think it's almost level but not quite.
0:06:45 > 0:06:48I think we need just a little bit more.
0:06:48 > 0:06:51Has anyone else in the audience got any gold?
0:06:51 > 0:06:53LAUGHTER
0:06:53 > 0:06:56I found some on the way in.
0:06:56 > 0:06:57Oh, you've got some?
0:06:57 > 0:07:01Isn't that Nobel prize-winning chemist Prof Sir Harry Kroto?
0:07:01 > 0:07:03I think it is.
0:07:03 > 0:07:05APPLAUSE
0:07:13 > 0:07:16So what exactly...I think I might know what this is.
0:07:16 > 0:07:21- Is this really your Nobel Prize? - Yes, they give them away.
0:07:21 > 0:07:26- This is solid gold, isn't it? - It's solid gold. And I want it back.
0:07:26 > 0:07:31- Well, of course, Harry. - I trust you.- Oh, thank you.
0:07:31 > 0:07:34Right, anyway, maybe this is just what we need.
0:07:34 > 0:07:36Let's just try that on there.
0:07:38 > 0:07:41Oh, I think that's pretty well balanced now.
0:07:41 > 0:07:42I think that's quite amazing.
0:07:42 > 0:07:47I think that is 43kg of gold and one Nobel Prize.
0:07:47 > 0:07:50Thank you very much. Big round of applause.
0:07:50 > 0:07:52Stay where you are for a moment.
0:07:52 > 0:07:54APPLAUSE
0:07:54 > 0:07:58Thank you, Prof Kroto, for saving the day. This is quite amazing.
0:07:58 > 0:08:0143kg, but it doesn't actually look too much there, does it, Emma?
0:08:01 > 0:08:03What do you think?
0:08:03 > 0:08:05As you say, it's very dense
0:08:05 > 0:08:08and this is why it doesn't actually take up much space.
0:08:08 > 0:08:12If you were made of gold, you would weigh 800kg,
0:08:12 > 0:08:15which is about as much as a small car.
0:08:15 > 0:08:19Which is quite a lot really, isn't it? So that's pretty impressive.
0:08:19 > 0:08:22How much do you think this is worth? How much do you think? Have a guess.
0:08:22 > 0:08:25Um...quite a lot.
0:08:25 > 0:08:28I think you're right there. Quite a lot, yes.
0:08:28 > 0:08:31Anyone have any other ideas? Shout it out. Yes?
0:08:31 > 0:08:34- One million?- One million, actually, you're not far off.
0:08:34 > 0:08:36It is even more than that.
0:08:36 > 0:08:41This is about £1.5 million worth of gold just sitting here.
0:08:41 > 0:08:45Which is pretty impressive, isn't it? All right, now.
0:08:45 > 0:08:47If you just stay where you are sitting, please.
0:08:47 > 0:08:51I need to unload this first of all. I'll just take that and...
0:08:51 > 0:08:53LAUGHTER
0:08:53 > 0:08:56Just going to put these over here.
0:08:59 > 0:09:01A few little bits left.
0:09:02 > 0:09:06There we are. That's fantastic. OK, thank you very much, Emma.
0:09:06 > 0:09:07Big round of applause.
0:09:07 > 0:09:09APPLAUSE
0:09:14 > 0:09:18Gold really is an incredibly dense substance.
0:09:18 > 0:09:21But actually, it's not the densest element.
0:09:21 > 0:09:24Could we just have cards up for a second, please?
0:09:24 > 0:09:30That honour goes to osmium. You are the densest thing in the universe.
0:09:30 > 0:09:33Well, at least on Earth. Did you know that?
0:09:33 > 0:09:36I don't mean that in a bad way. This is just you as an element.
0:09:36 > 0:09:38Osmium is incredibly dense indeed.
0:09:38 > 0:09:41Can we just keep the cards up for the people in the same row
0:09:41 > 0:09:44as osmium and gold. Everyone else down.
0:09:44 > 0:09:48Caesium stay up, barium stay up. All the way over to mercury.
0:09:48 > 0:09:53Why is it, then, that these elements are so incredibly dense?
0:09:53 > 0:09:57The most dense element is osmium, closely followed by iridium.
0:09:57 > 0:10:00Well, atoms after osmium, iridium, gold,
0:10:00 > 0:10:02all these other ones are getting heavier.
0:10:02 > 0:10:04So the atoms themselves are heavier
0:10:04 > 0:10:07and yet these ones are the most tightly packed.
0:10:07 > 0:10:10So it's not just to do with how heavy the atoms are.
0:10:10 > 0:10:13We also need to look at the bonding that we have between them.
0:10:13 > 0:10:16And this is what we can see in the graph here.
0:10:16 > 0:10:19This shows how much energy we need to put in to separate
0:10:19 > 0:10:22a certain number of atoms of these elements.
0:10:22 > 0:10:26And we see that we've got a peak around tungsten.
0:10:26 > 0:10:29This is why we use tungsten in light bulb filaments,
0:10:29 > 0:10:31because it's very difficult to pull them apart.
0:10:31 > 0:10:33And we have very high temperatures.
0:10:33 > 0:10:37But as we go beyond tungsten, the bonding isn't quite so strong
0:10:37 > 0:10:39but the atoms are getting heavier.
0:10:39 > 0:10:43And so it's bit of a balance between the strength of the bonds,
0:10:43 > 0:10:46how tightly they are packed, and how heavy the atoms are.
0:10:46 > 0:10:50This is why we reach a maximum for osmium and iridium.
0:10:50 > 0:10:54Gold, platinum and so on are still very dense afterwards,
0:10:54 > 0:10:57but the maximum is there for osmium and iridium.
0:10:57 > 0:11:00So osmium is even more expensive than gold, in fact.
0:11:00 > 0:11:03And if someone was really going to pay you a compliment
0:11:03 > 0:11:07they would say, "You are worth your weight in osmium."
0:11:07 > 0:11:11Actually, these metals are not the only precious things
0:11:11 > 0:11:13we can extract from the earth.
0:11:13 > 0:11:17There are even non-metals that we can sometimes find as well.
0:11:17 > 0:11:20Hello. Hello, Prof Kroto.
0:11:20 > 0:11:24I'm assuming you would like your Nobel Prize, would you?
0:11:24 > 0:11:28- I'd swap it for those bigger ones. - Yes, so would I, I think.
0:11:28 > 0:11:31Well, there we go. Thank you very much.
0:11:31 > 0:11:35Perhaps you could tell us what you won the Nobel Prize for.
0:11:35 > 0:11:39It's for discovering an alternative to these.
0:11:39 > 0:11:42This is graphite and this is diamond. These structures.
0:11:42 > 0:11:45These are actually the only ones that I knew about
0:11:45 > 0:11:46when I was at school.
0:11:46 > 0:11:49In the text books, there were just two types of carbon.
0:11:49 > 0:11:51Two different forms called allotropes.
0:11:51 > 0:11:53One has this arrangement. This one is the graphite.
0:11:53 > 0:11:56This is the sort of thing you find in your pencils.
0:11:56 > 0:11:59It's pretty soft and well, carbon, it's just an arrangement of carbon.
0:11:59 > 0:12:02Diamond looks very different though, doesn't it?
0:12:02 > 0:12:05I don't suppose...you've very kindly lent us your gold,
0:12:05 > 0:12:08I don't suppose you have a spare diamond on you, do you?
0:12:08 > 0:12:11I don't myself but my wife actually has one.
0:12:11 > 0:12:15- A-ha!- You don't want to take that as well, do you?- Well, just borrow it.
0:12:19 > 0:12:21- I hope I get it back.- Thank you, Mrs Kroto. Of course, yes.
0:12:21 > 0:12:24You can trust me.
0:12:24 > 0:12:30This is a beautiful ring here. Is it an engagement ring or something?
0:12:30 > 0:12:32It's really quite lovely.
0:12:32 > 0:12:34The diamond comes out quite easily, doesn't it? Yes.
0:12:34 > 0:12:35LAUGHTER
0:12:35 > 0:12:38We can see it more clearly now. Look at that. It's beautiful.
0:12:38 > 0:12:42What a beautiful diamond. It is a real diamond though, is it?
0:12:42 > 0:12:46- It as real as you can get. - It's quite stunning.
0:12:46 > 0:12:52Of course, we want to show that this graphite is made up of carbon.
0:12:52 > 0:12:53There is one way we can do this.
0:12:53 > 0:12:57We can burn our carbon in oxygen and we'll get, what would we get?
0:12:57 > 0:13:01- Carbon dioxide.- See? He's pretty good. Carbon dioxide.
0:13:01 > 0:13:05- And then if we bubble that through lime water?- Calcium carbonate.
0:13:05 > 0:13:08Calcium carbonate. That's the test for carbon dioxide, of course.
0:13:08 > 0:13:10- And it would be white. - I didn't ask you that one.
0:13:10 > 0:13:14You are getting carried away now. Let's just see this over here.
0:13:14 > 0:13:16We have some apparatus.
0:13:16 > 0:13:19This is where we are going to burn some graphite
0:13:19 > 0:13:22and show that it is made of carbon.
0:13:22 > 0:13:25What's bubbling through here is just oxygen.
0:13:25 > 0:13:28This won't react with our lime water at all.
0:13:28 > 0:13:32We are going to see if we can light the graphite
0:13:32 > 0:13:37and get it burning inside the oxygen. There we are. Thank you.
0:13:37 > 0:13:40That's great. So now we have a hydrogen flame.
0:13:40 > 0:13:44This won't produce anything. It's only going to produce water.
0:13:44 > 0:13:47You can see the water just beginning to condense.
0:13:47 > 0:13:50Beautiful. I'm going to turn the flame off.
0:13:52 > 0:13:54- Look at that. What do you think? - It's brilliant.
0:13:54 > 0:13:56It is literally brilliant, yes.
0:13:56 > 0:14:02This is the carbon combining with oxygen that's flowing through here.
0:14:02 > 0:14:06Hopefully, we are going to see this changing colour, giving us
0:14:06 > 0:14:09a milky colour. Showing that there is carbon dioxide present.
0:14:09 > 0:14:13I think we should test diamond as well, don't you? What do you think?
0:14:13 > 0:14:14ALL: Yes!
0:14:14 > 0:14:17Yes? Does Mrs Kroto mind?
0:14:17 > 0:14:20- OK.- In the name of science. That's very kind of you.
0:14:20 > 0:14:23Harry seems a little nervous. Are you sure this is a real diamond?
0:14:23 > 0:14:27- I think it's a real diamond, yes. - Let's give it a go then.
0:14:27 > 0:14:31We will just put it on there. And again, we'll put this on here.
0:14:33 > 0:14:38Right, so we have our flame. Here we go. The moment of truth.
0:14:38 > 0:14:44Now can we get our diamond to burn in the oxygen?
0:14:45 > 0:14:47WATER BUBBLES
0:14:54 > 0:14:57Ah, look at that!
0:14:57 > 0:14:59I hope you can afford to pay for this.
0:14:59 > 0:15:02The good news is, Harry, it is a real diamond.
0:15:02 > 0:15:04LAUGHTER
0:15:04 > 0:15:05OK.
0:15:06 > 0:15:08I think this is absolutely stunning.
0:15:08 > 0:15:13That diamond there, it is burning in oxygen.
0:15:13 > 0:15:15It's combining with the oxygen of the air.
0:15:15 > 0:15:18- Have you ever seen a diamond burning like that before?- No, I haven't.
0:15:18 > 0:15:20- It is quite stunning to see. - That's right.
0:15:20 > 0:15:23There are no flames coming from this.
0:15:23 > 0:15:28So this is just the heat of the reaction as the carbon combines
0:15:28 > 0:15:31with the oxygen that's present, flowing through here,
0:15:31 > 0:15:35forming carbon dioxide. That is absolutely stunning.
0:15:35 > 0:15:37Just look at that. It's glowing all by itself.
0:15:37 > 0:15:40It's absolutely brilliant. I think that's amazing.
0:15:40 > 0:15:44And look, our lime water is going milky.
0:15:44 > 0:15:48It's the most expensive lime water I've ever seen.
0:15:48 > 0:15:50I think you are probably right there.
0:15:50 > 0:15:53It really is the most expensive lime water you've ever seen.
0:15:53 > 0:15:57- Well, we are waiting for your diamond just to...- Disappear.
0:15:57 > 0:15:59To disappear, yes.
0:15:59 > 0:16:02Maybe you could tell us about your Nobel Prize again.
0:16:02 > 0:16:06- I think it has something to do with this.- I think it does, yes.
0:16:06 > 0:16:09Would you like to come round to the front, actually.
0:16:09 > 0:16:10We'll compare it to these ones.
0:16:10 > 0:16:14This one was the graphite. This is the diamond.
0:16:14 > 0:16:18And this is the third form, the well-characterised form.
0:16:18 > 0:16:22It consists of 60 carbon atoms in the shape of a soccer ball.
0:16:22 > 0:16:26And it was such a fantastic surprise when we discovered it.
0:16:26 > 0:16:31One of the clues to its structure was Mr Fuller's geodesic domes.
0:16:31 > 0:16:35In Montreal, we had visited that. And I remembered it.
0:16:35 > 0:16:37It was in a book of mine
0:16:37 > 0:16:42and when we were trying to work out how a sheet of graphite like this,
0:16:42 > 0:16:45or a graphing sheet, might close up,
0:16:45 > 0:16:50what we discovered was, it could close up if it had 12 pentagons.
0:16:50 > 0:16:53You cannot close a sheet of hexagons up. It won't close up.
0:16:53 > 0:16:56But if you have 12 pentagons, it will.
0:16:56 > 0:16:59And you are all familiar with that in the case of the normal
0:16:59 > 0:17:04soccer ball with 12 black pentagons and 20 hexagons.
0:17:04 > 0:17:08And that's the magic that Mr Fuller knew, and other people as well.
0:17:08 > 0:17:12And I called it Buckminsterfullerene
0:17:12 > 0:17:15because there are double bonds as there are in benzene.
0:17:15 > 0:17:19So the "ene" ending was just a beautiful sort of ending
0:17:19 > 0:17:21to a great name.
0:17:21 > 0:17:25So since my time at school, the textbooks have to be rewritten
0:17:25 > 0:17:29with a new form of carbon discovered by this chap here.
0:17:29 > 0:17:33- And colleagues in the States.- And your co-workers in the States.
0:17:33 > 0:17:36We should have another look at your diamond here.
0:17:36 > 0:17:39It seems to have decreased in size.
0:17:39 > 0:17:41I think we should come clean.
0:17:41 > 0:17:45Don't worry, we didn't destroy Mrs Kroto's engagement ring.
0:17:45 > 0:17:50That really would be quite harsh. This is a pretty low-grade diamond.
0:17:50 > 0:17:53It still looks pretty good to the naked eye
0:17:53 > 0:17:55but the experts say it's not very valuable at all.
0:17:55 > 0:17:57But it is a real diamond.
0:17:57 > 0:17:59And it is combining with oxygen
0:17:59 > 0:18:03and I think that's a pretty stunning reaction. Thank you, Prof Kroto.
0:18:03 > 0:18:05It's a real privilege to have a Nobel Prize winner here,
0:18:05 > 0:18:08helping out with an experiment. Thank you very much.
0:18:08 > 0:18:09APPLAUSE
0:18:12 > 0:18:17So is it possible that we could take this worthless carbon dioxide
0:18:17 > 0:18:20and get our diamond back from that?
0:18:20 > 0:18:23I mean, that really would be the alchemist's dream.
0:18:23 > 0:18:26Recovering something precious from something worthless.
0:18:26 > 0:18:30We've got a demonstration here that shows that this may be possible.
0:18:30 > 0:18:32I'll just turn this round.
0:18:34 > 0:18:38Now this tank is filled with carbon dioxide gas.
0:18:38 > 0:18:41We've put some solid carbon dioxide in the bottom,
0:18:41 > 0:18:44which is slowly evaporating, turning into the gas.
0:18:44 > 0:18:47We can't see the gas because, of course, it's colourless.
0:18:47 > 0:18:50But it is there. How can we test for this?
0:18:50 > 0:18:53Does anyone know another use for carbon dioxide? Yes?
0:18:53 > 0:18:55- To put out flames. - To put out flames, yes, exactly.
0:18:55 > 0:18:59I wonder if we have a flame, please. Is there a flame anywhere?
0:18:59 > 0:19:05Ah, yes. Here is a flame that certainly needs putting out.
0:19:05 > 0:19:08If I just lower this into the tank...
0:19:10 > 0:19:12There we are. You can see that it goes out.
0:19:12 > 0:19:16This is because, of course, the tank is filled with carbon dioxide.
0:19:16 > 0:19:19And carbon dioxide doesn't support combustion.
0:19:20 > 0:19:27Right, now then. We have also placed in this tank some magnesium metal.
0:19:27 > 0:19:29I'm just going to fish this out.
0:19:32 > 0:19:36This is a little nest of magnesium metal.
0:19:36 > 0:19:38I'm going to light the magnesium here
0:19:38 > 0:19:42and it burns with a brilliant white flame. There we are.
0:19:42 > 0:19:46Now I'm going to lower this into the carbon dioxide.
0:19:46 > 0:19:49It seems to be burning even more vigorously now.
0:19:49 > 0:19:51The flame is still burning.
0:19:53 > 0:19:58But what about this? This one...well, this one still goes out.
0:19:59 > 0:20:04Our petrol is extinguished in the carbon dioxide,
0:20:04 > 0:20:07but the magnesium is reacting with it.
0:20:07 > 0:20:12The magnesium is stealing the oxygen away from the carbon dioxide
0:20:12 > 0:20:15and, well, we'll have a look at what we've got at the bottom
0:20:15 > 0:20:18but let me take this out. You can see magnesium oxide
0:20:18 > 0:20:21covered over what was the magnesium here,
0:20:21 > 0:20:26but look in the centre. What we've now got is black carbon.
0:20:28 > 0:20:32The magnesium removes the oxygen leaving behind the carbon
0:20:32 > 0:20:34from the carbon dioxide.
0:20:34 > 0:20:38We can get our carbon back from carbon dioxide
0:20:38 > 0:20:42but, well, it's not a diamond yet.
0:20:42 > 0:20:47Is it possible to turn that carbon into a diamond?
0:20:47 > 0:20:52Well, actually, this is what happens deep within the earth,
0:20:52 > 0:20:55and this is a diamond in a rock
0:20:55 > 0:21:00just as it would have come out of the earth.
0:21:00 > 0:21:02This is really quite beautiful indeed.
0:21:02 > 0:21:06Deep within the earth, the carbon is heated up
0:21:06 > 0:21:09and compressed with huge temperatures, huge pressures,
0:21:09 > 0:21:12and the carbon we saw there, the black carbon,
0:21:12 > 0:21:16is converted into diamond.
0:21:16 > 0:21:19Recently, chemists have learnt how to copy this process,
0:21:19 > 0:21:24how to turn graphite or other forms of carbon into diamond.
0:21:24 > 0:21:28I'd like a volunteer to help me out with this one, please.
0:21:28 > 0:21:32Would you like to come down to the front, please?
0:21:32 > 0:21:34APPLAUSE
0:21:34 > 0:21:37If you'd like to come down to the front. Your name is...?
0:21:37 > 0:21:42- Lewis.- Lewis, OK. Now, this is a diamond.
0:21:42 > 0:21:45Would you like to just hold this?
0:21:45 > 0:21:47- What do you think, are you impressed?- Yeah.
0:21:47 > 0:21:51Looks like a piece of glass, doesn't it? It actually really is a diamond.
0:21:51 > 0:21:54This is a synthetically grown diamond and this has been prepared
0:21:54 > 0:21:58not from the high temperature, high pressure system that we also use,
0:21:58 > 0:22:01this is a technique called chemical vapour deposition
0:22:01 > 0:22:04where the diamond is gradually built up a layer at a time.
0:22:04 > 0:22:08I'd like you to take this, not keep it, but bring it over here
0:22:08 > 0:22:10and just place it on top.
0:22:10 > 0:22:14This is some ice here. Hold it like this.
0:22:14 > 0:22:19Just put that on top of there and push through this ice.
0:22:19 > 0:22:22- How does that feel?- Cold.- It feels very cold and what's happening?
0:22:22 > 0:22:24Water's coming off.
0:22:24 > 0:22:28This is ice, solid ice, and it seems to be going...
0:22:28 > 0:22:31You've chopped all the way through this quite cleanly there.
0:22:31 > 0:22:33As you say, it's got very cold.
0:22:33 > 0:22:35- Do you know why it's got colder? - No idea.
0:22:35 > 0:22:38It's used your energy to heat up this block of ice,
0:22:38 > 0:22:41so yes, you're getting cold because it's taking the energy
0:22:41 > 0:22:44from your fingers here. Let's try this again.
0:22:44 > 0:22:47If I just put this on here, it slices through like butter.
0:22:47 > 0:22:50It's really quite amazing. It feels very strange.
0:22:50 > 0:22:54- I'm not sawing.- It's not cutting because it's hard,
0:22:54 > 0:22:57it's cutting because it's a very good conductor of heat.
0:22:57 > 0:23:01Quite remarkable, so cleanly through this block of ice.
0:23:01 > 0:23:04Feels very strange. Thank you very much, thank you for that.
0:23:04 > 0:23:07APPLAUSE
0:23:08 > 0:23:10That remarkable property of diamond
0:23:10 > 0:23:13was because it's an incredible conductor of heat.
0:23:13 > 0:23:16To demonstrate this and explain why this is so,
0:23:16 > 0:23:19I'd like some other volunteers, please.
0:23:19 > 0:23:22I'd like six people so if we could have all of you, six of you,
0:23:22 > 0:23:25if you could come down to the front, please?
0:23:25 > 0:23:30In a row, facing the audience. Sit next to each other.
0:23:30 > 0:23:33I'd like all of you to face that direction, please,
0:23:33 > 0:23:35turn around and face that way.
0:23:35 > 0:23:38Just close up a little bit, a little bit friendlier.
0:23:38 > 0:23:41Come this way, please. Lovely job. Close up there
0:23:41 > 0:23:45and put your hands on the shoulders of the person in front.
0:23:45 > 0:23:47Face that way. That's good.
0:23:47 > 0:23:50Now, at the moment, these are all pretty weak bonds here.
0:23:50 > 0:23:53Watch what happens when I give a bit of energy this way.
0:23:53 > 0:23:55Don't do anything, just behave normally.
0:23:55 > 0:23:58Lucy, can you feel anything?
0:23:58 > 0:24:01It was very difficult to get this energy through there
0:24:01 > 0:24:04and this is because of all these weak bonds.
0:24:04 > 0:24:07What I'd like you to do is just spread yourselves out a little more
0:24:07 > 0:24:10and hold arms with very rigid arms.
0:24:10 > 0:24:13Rigid, straight arms. That's it.
0:24:13 > 0:24:16Now I'm just going to do the same thing again.
0:24:16 > 0:24:21Give you a jolt that end and now you can see you're certainly moving.
0:24:21 > 0:24:25Thank you very much indeed, thank you for all your help.
0:24:25 > 0:24:27APPLAUSE
0:24:27 > 0:24:33This is why our diamond is such a good conductor of thermal energy.
0:24:33 > 0:24:38It's because the bonds are so strong holding these carbon atoms together,
0:24:38 > 0:24:42they're so rigid, that this energy is very easily transmitted through.
0:24:42 > 0:24:46Diamond is the best conductor of heat of any substance known,
0:24:46 > 0:24:50until very recently when scientists discovered a new form of carbon,
0:24:50 > 0:24:54another form, called graphene, which is a single sheet of graphite.
0:24:54 > 0:24:59That is an even better conductor of heat. They're the best ones known.
0:25:01 > 0:25:04We've seen then that we can convert charcoal,
0:25:04 > 0:25:08we convert graphite into diamond under very high pressures
0:25:08 > 0:25:11or using the other technique of chemical vapour deposition.
0:25:11 > 0:25:16Surely if the alchemists had focused on that, they would have changed
0:25:16 > 0:25:20their attention away from trying to turn base metals into gold.
0:25:20 > 0:25:23But of course, they were focused on metals because metals
0:25:23 > 0:25:26were incredibly important and still are very important.
0:25:26 > 0:25:28It's only gold that has this unique property
0:25:28 > 0:25:33that we can find it lying around. Most metals we find in their ores.
0:25:33 > 0:25:35Ores like this here.
0:25:35 > 0:25:40This is the natural mineral - does anybody know what it is?
0:25:40 > 0:25:42It is an iron ore.
0:25:42 > 0:25:46Does anyone know what the name of the iron ore would be?
0:25:46 > 0:25:48Very good, you're doing well. Hematite it is.
0:25:48 > 0:25:51This is the mineral hematite.
0:25:51 > 0:25:54This is now our source for iron
0:25:54 > 0:25:59but it's locked up with the iron combined with oxygen.
0:25:59 > 0:26:03Somehow we have to learn how to extract the metal out of this.
0:26:03 > 0:26:06After all, it doesn't just fall from the skies.
0:26:06 > 0:26:11But remarkably, sometimes it does just fall from the skies
0:26:11 > 0:26:14and this is what we have here.
0:26:14 > 0:26:17This is actually very heavy as well.
0:26:17 > 0:26:22This is a lump of iron that did fall from the skies about 5,000 years ago
0:26:22 > 0:26:26and it landed in Australia. Look at this.
0:26:26 > 0:26:29What I wanted to show you here was the comparison
0:26:29 > 0:26:31between these two pieces.
0:26:31 > 0:26:36We can see that this is developing this reddish-brown colour,
0:26:36 > 0:26:39the same as the hematite.
0:26:39 > 0:26:41This contains iron. It is a slice of iron
0:26:41 > 0:26:44but it is gradually combining with oxygen
0:26:44 > 0:26:46to form this mineral hematite.
0:26:46 > 0:26:49We can show that it is a meteorite
0:26:49 > 0:26:52if we were to take a slice through this.
0:26:52 > 0:26:55If we took a slice through this,
0:26:55 > 0:26:58what we would see is something like this.
0:26:58 > 0:27:05This is a slice through a meteorite and it's really quite beautiful.
0:27:05 > 0:27:07This has been cut and we can see the side here.
0:27:07 > 0:27:10This is the outer surface of the meteorite
0:27:10 > 0:27:13and here it's been cut with this incredible pattern here.
0:27:13 > 0:27:17This pattern has been etched with acid.
0:27:17 > 0:27:21It etches away certain types of the minerals that are in here.
0:27:21 > 0:27:25The forms of the iron, it etches away certain of them
0:27:25 > 0:27:28and it reveals this beautiful crystal structure
0:27:28 > 0:27:30and this proves that it's a meteorite,
0:27:30 > 0:27:34because it's impossible to get this pattern here on Earth.
0:27:34 > 0:27:36That's because we need to cool down molten iron
0:27:36 > 0:27:38with a little bit of nickel in.
0:27:38 > 0:27:41We'd need to cool it down over such a slow rate,
0:27:41 > 0:27:44just one degree over thousands of years,
0:27:44 > 0:27:46if we wanted to see these crystals develop.
0:27:46 > 0:27:50This really is quite stunning indeed.
0:27:50 > 0:27:55Over time, the metal of this beautiful meteorite
0:27:55 > 0:27:58will turn into this ore here.
0:27:58 > 0:28:00We can't wait thousands of years to see that
0:28:00 > 0:28:02but we can speed this process up
0:28:02 > 0:28:07and we can show how iron combines with the oxygen to form iron oxide.
0:28:07 > 0:28:10I'd like a volunteer for this one, please.
0:28:10 > 0:28:12I'd like someone from this side, who shall we have?
0:28:12 > 0:28:15Would you like to come down to the front, please?
0:28:15 > 0:28:18APPLAUSE
0:28:18 > 0:28:21- Would you like to tell us your name, please?- Rose.
0:28:21 > 0:28:24Rose, OK, we have some iron over here. This is just iron wool.
0:28:24 > 0:28:26Would you like to feel this?
0:28:26 > 0:28:29It's just the sort of thing you would use to clean your pots
0:28:29 > 0:28:31and pans if you're helping out at home.
0:28:31 > 0:28:33Now, I'll put on my goggles
0:28:33 > 0:28:36and we're going to combine this with some oxygen.
0:28:36 > 0:28:42We want to see how much this weighs by itself. This weighs 15.9 grams.
0:28:42 > 0:28:44Now, the question is, what will happen
0:28:44 > 0:28:47when this combines with the oxygen from the air?
0:28:47 > 0:28:49How do you think its mass will change?
0:28:49 > 0:28:52Will it go up, go down, stay the same?
0:28:52 > 0:28:54What do you think, when it burns?
0:28:54 > 0:28:56- It will go up?- It will go up, and why's that?
0:28:56 > 0:29:01- Because it will become more dense. - It will become more dense.
0:29:01 > 0:29:03Let's have a look and see, shall we?
0:29:03 > 0:29:05I'm just going to apply a light here.
0:29:05 > 0:29:09This beautiful reaction is the iron combining with the oxygen
0:29:09 > 0:29:11and look what's happened to the mass.
0:29:11 > 0:29:15It's gone down. It's getting lower.
0:29:15 > 0:29:19-0.16, so whoever said it goes down, you're quite right.
0:29:19 > 0:29:22But look now what's happening. It's going up again.
0:29:22 > 0:29:25It's is getting heavier so whoever said it goes up, you're quite right.
0:29:25 > 0:29:28Everyone's right, that's good. Why did it go down?
0:29:28 > 0:29:32It went down initially because this iron wool was treated with oil,
0:29:32 > 0:29:37just to try and stop it combining with the oxygen from the air.
0:29:37 > 0:29:40Once this reaction has started, it is combining with oxygen
0:29:40 > 0:29:43and that's why it's getting heavier. You were quite right.
0:29:43 > 0:29:47It is getting heavier because the iron is forming iron oxide.
0:29:47 > 0:29:49Thank you very much indeed.
0:29:49 > 0:29:52APPLAUSE
0:29:54 > 0:29:56Iron is pretty reactive stuff.
0:29:56 > 0:29:58It reacts with oxygen and this is how
0:29:58 > 0:30:02we would normally find our metal, combined with oxygen.
0:30:02 > 0:30:06What about if you couldn't extract the iron from this?
0:30:06 > 0:30:08What about before we knew how to do this?
0:30:08 > 0:30:11The only iron that we would have had would have been iron
0:30:11 > 0:30:14from a natural source such as this meteorite.
0:30:14 > 0:30:18This sort of iron was used to make tools and so on.
0:30:18 > 0:30:22I think we have an example of a tool using some natural iron here.
0:30:22 > 0:30:24Would you please welcome Dr Caroline Smith
0:30:24 > 0:30:27from the Natural History Museum.
0:30:27 > 0:30:29APPLAUSE
0:30:31 > 0:30:34This is really beautiful. What exactly is this?
0:30:34 > 0:30:38This is an Inuit knife and it's made of walrus tusk,
0:30:38 > 0:30:42so walrus ivory, but in the end you can hopefully see
0:30:42 > 0:30:45it actually has an iron blade.
0:30:45 > 0:30:48When this was discovered, the Inuits hadn't yet learnt
0:30:48 > 0:30:51how to make iron, how to extract it from the ore.
0:30:51 > 0:30:54That's right. They had to have a source of metallic iron.
0:30:54 > 0:30:57At the time, it was thought that the iron in this knife
0:30:57 > 0:31:01was actually from a meteorite called the Cape York meteorite,
0:31:01 > 0:31:04a very large meteorite which was found in Greenland.
0:31:04 > 0:31:06This knife actually came from Greenland,
0:31:06 > 0:31:09but we're not actually sure that's right, now,
0:31:09 > 0:31:11we think it might be from somewhere else.
0:31:11 > 0:31:14I gather that you've performed an analysis on this
0:31:14 > 0:31:17and more research suggests that you are beginning to question
0:31:17 > 0:31:21whether this is a meteorite, but it has to be naturally occurring
0:31:21 > 0:31:23because they didn't have the technology.
0:31:23 > 0:31:26Exactly. They didn't have the technology to extract iron
0:31:26 > 0:31:29from things like hematite so they had to have a source
0:31:29 > 0:31:30of native iron, metallic iron.
0:31:30 > 0:31:33We think now that maybe this is actually from a place
0:31:33 > 0:31:35called Disko Island,
0:31:35 > 0:31:37which is an island off the west coast of Greenland,
0:31:37 > 0:31:41and it's one of the very few locations on earth
0:31:41 > 0:31:45where you get metallic iron existing in metallic form.
0:31:45 > 0:31:48You very kindly brought a couple of samples for us.
0:31:48 > 0:31:51These are from Disko Island.
0:31:51 > 0:31:56They look quite different but this one clearly looks very metallic.
0:31:56 > 0:31:58You can see this here, it's got quite a shine to it.
0:31:58 > 0:32:01- It's quite a heavy specimen. - It is very heavy.
0:32:01 > 0:32:05This looks like a piece of iron but this is naturally occurring iron?
0:32:05 > 0:32:08This is naturally occurring iron found at the surface of the Earth.
0:32:08 > 0:32:11In fact, tons of this iron has been found.
0:32:11 > 0:32:15But why hasn't this one corroded into the hematite?
0:32:15 > 0:32:18What we think happened is that about 55 million years ago,
0:32:18 > 0:32:21lava was erupted in this place, in Disko Island,
0:32:21 > 0:32:23and as the lava was coming up,
0:32:23 > 0:32:28it went through sedimentary rocks that have got a lot of carbon in,
0:32:28 > 0:32:29and the lava picked the carbon up
0:32:29 > 0:32:33and you've got a chemical reaction happening where the iron,
0:32:33 > 0:32:36which was bonded with oxygen just like here in the hematite,
0:32:36 > 0:32:40actually became metallic iron. It reduced the iron from the lava.
0:32:40 > 0:32:44We can see this is also a sample of iron, so this is iron.
0:32:44 > 0:32:46This is a sample of lava from Disko Island
0:32:46 > 0:32:50so there is some metal in there but not as big as that.
0:32:50 > 0:32:53This one is a very grey colour and that's due to the graphite
0:32:53 > 0:32:55and carbon in here?
0:32:55 > 0:32:58You can see a bit of a smudge on the paper.
0:32:58 > 0:33:00There's a black smear there.
0:33:00 > 0:33:03That's just from the carbon that's present in here, the graphite?
0:33:03 > 0:33:07- That's right.- Actually, we've got a clip of a blast furnace to show.
0:33:07 > 0:33:10This is how iron is now manufactured
0:33:10 > 0:33:14and this is using carbon to steal away the oxygen from the iron ore,
0:33:14 > 0:33:16from the hematite.
0:33:16 > 0:33:19This is how we're producing iron but what you're saying now is that...
0:33:19 > 0:33:22Nature beat us to it about 55 million years ago.
0:33:22 > 0:33:24- Exactly.- That is quite amazing.
0:33:24 > 0:33:29Thank you very much for bringing these samples on.
0:33:32 > 0:33:36Now, I really wanted to produce some molten iron for you
0:33:36 > 0:33:39here in the lecture theatre, but clearly we couldn't bring in
0:33:39 > 0:33:42a blast furnace, so we had to think of another way to do this.
0:33:42 > 0:33:45We can learn from what we did earlier,
0:33:45 > 0:33:49when we used the magnesium metal to steal the oxygen away
0:33:49 > 0:33:51from the carbon dioxide.
0:33:51 > 0:33:53We can do the same thing now with our iron oxide.
0:33:53 > 0:33:56We can use a more reactive metal
0:33:56 > 0:33:59and we are going to use the metal, aluminium.
0:33:59 > 0:34:04You may be wondering why there's a safe under here.
0:34:04 > 0:34:07This is because we have a bit of an embarrassing story here.
0:34:07 > 0:34:14We accidentally locked Andy's Christmas bonus in the safe.
0:34:14 > 0:34:17We tried getting into the safe and it's pretty hard.
0:34:17 > 0:34:23It's made of pretty solid stuff. We can't really get into this
0:34:23 > 0:34:27but the energy generated as the oxygen is taken away
0:34:27 > 0:34:32by the aluminium to form iron should be enough to get in here.
0:34:32 > 0:34:34Can we have a little look in here?
0:34:34 > 0:34:37Get the camera right in to show what's inside this vessel.
0:34:37 > 0:34:41This is made of a very tough form of carbon. This is made of graphite,
0:34:41 > 0:34:44and you may be able to see the orangey colour.
0:34:44 > 0:34:49That's our iron oxide. It's mixed with aluminium powder.
0:34:49 > 0:34:52The thing you see sticking out there is a little bit of magnesium
0:34:52 > 0:34:54I'm going to use to start this reaction.
0:34:54 > 0:34:57Hopefully, we should generate some iron
0:34:57 > 0:34:59and see if we can get through into the safe.
0:34:59 > 0:35:03- Sounds like a good idea, doesn't it? - If it's the only way to do it.
0:35:03 > 0:35:08I think we will need a safety screen around this, though.
0:35:08 > 0:35:14I'm going to need a glove as well. Thank you very much.
0:35:14 > 0:35:17- Feeling confident?- Yeah, I can't see what could go wrong.
0:35:17 > 0:35:20What could possibly go wrong? Exactly.
0:35:20 > 0:35:23Let's give it a go. You'll see a bright white light first of all.
0:35:23 > 0:35:25That's just the magnesium we saw earlier.
0:35:25 > 0:35:28The magnesium combining with the oxygen from the air.
0:35:31 > 0:35:36OK. We should know when it starts. I think it's started now!
0:35:36 > 0:35:40This is our little blast furnace here. Look at that, fantastic.
0:35:40 > 0:35:43We've got some molten metal there. Can we lose the safety screen?
0:35:43 > 0:35:47That would be good if we can possibly take this off. Lovely job.
0:35:47 > 0:35:52Right off the top very carefully. I'm just going to see...
0:35:52 > 0:35:56I'll give you that, see if we can pick up this.
0:35:56 > 0:35:59What have we got here? Yes, that's wonderful.
0:35:59 > 0:36:02It releases such an enormous amount of energy
0:36:02 > 0:36:06as the aluminium combines with the oxygen from the iron oxide.
0:36:06 > 0:36:08Good news, Andy. Good news and bad news.
0:36:08 > 0:36:12The good news is there's a hole in the top of the safe.
0:36:12 > 0:36:15The bad news is there's a lot of smoke coming from outside.
0:36:15 > 0:36:19I think I've just found the key as well!
0:36:19 > 0:36:22Now he finds the key! At least we got into the safe, well done.
0:36:22 > 0:36:25Thank you very much for that.
0:36:25 > 0:36:27APPLAUSE
0:36:27 > 0:36:30We formed there during that reaction aluminium oxide
0:36:30 > 0:36:33as the aluminium took the oxygen away.
0:36:33 > 0:36:35This is how we find aluminium in nature.
0:36:35 > 0:36:39We find it as aluminium oxide and here's a sample here.
0:36:39 > 0:36:42What do you think of that?
0:36:42 > 0:36:47It is light and this is because it's a very light metal, aluminium.
0:36:47 > 0:36:52How can we get our aluminium out of this rock?
0:36:52 > 0:36:55This, for a long time, was a great problem.
0:36:55 > 0:36:59It was only solved when chemists realised they could use
0:36:59 > 0:37:03an even more reactive metal and this was the metal over here,
0:37:03 > 0:37:05the metal potassium.
0:37:05 > 0:37:08When this was first discovered, it was a bit of a curiosity.
0:37:08 > 0:37:10There was this amazing substance, aluminium,
0:37:10 > 0:37:13and it did have very remarkable properties.
0:37:13 > 0:37:15I'll need another volunteer from the audience.
0:37:15 > 0:37:17We'll have someone this side.
0:37:17 > 0:37:20In the green, would you like to come down, please?
0:37:20 > 0:37:22APPLAUSE
0:37:25 > 0:37:29- Your name is?- Ailish. - Ailish, OK, great.
0:37:29 > 0:37:32Obviously you've seen a lot of aluminium before, haven't you?
0:37:32 > 0:37:35It's very cheap now because now we have worked out
0:37:35 > 0:37:37how to extract it from the ores, but initially,
0:37:37 > 0:37:41it was incredibly difficult and that made it incredibly expensive.
0:37:41 > 0:37:45In fact, so valuable and so strange that this chap,
0:37:45 > 0:37:47this is Napoleon III,
0:37:47 > 0:37:50he had a whole cutlery set made from aluminium.
0:37:50 > 0:37:53I think we have some aluminium utensils here
0:37:53 > 0:37:56so you have a look at these. What do you think?
0:37:56 > 0:37:58- Very light.- They are very light, aren't they?
0:37:58 > 0:37:59This was the remarkable thing.
0:37:59 > 0:38:03With Napoleon's cutlery set, he had his cutlery,
0:38:03 > 0:38:05and it was so valuable that if he had a huge feast,
0:38:05 > 0:38:09he would give his most honoured guests the aluminium cutlery
0:38:09 > 0:38:12and all the rest had to make do with gold.
0:38:12 > 0:38:14OK, it seems strange to us now
0:38:14 > 0:38:16because we do know how to extract aluminium
0:38:16 > 0:38:20and it is incredibly abundant and we can find loads of it around
0:38:20 > 0:38:22but it was very difficult to get it out.
0:38:22 > 0:38:24Can I just say, it does feel very light indeed.
0:38:24 > 0:38:27That is one of the remarkable properties.
0:38:27 > 0:38:30It isn't actually the lightest metal that's known.
0:38:30 > 0:38:34- Do you know what the lightest metal is?- Lithium.
0:38:34 > 0:38:37Oh, yes, you're quite right. It is lithium. Give us a wave, lithium!
0:38:37 > 0:38:41Lithium is in fact a metal and it is incredibly light.
0:38:41 > 0:38:45We have made the world's first lithium spoon,
0:38:45 > 0:38:49which is very exciting. Here it is.
0:38:49 > 0:38:52This is our special RI spoon.
0:38:54 > 0:38:57Isn't that beautiful? Would you like to feel this?
0:38:57 > 0:39:01- It's really light. - It really is. It's amazingly light.
0:39:01 > 0:39:04It feels almost like plastic but it is solid metal.
0:39:04 > 0:39:07It is quite remarkable, don't you think?
0:39:07 > 0:39:11This is my dinner, I think.
0:39:11 > 0:39:16Some soup. Of course, cutlery sinks in it,
0:39:16 > 0:39:21but would you just drop it in and step back?
0:39:21 > 0:39:23Look at that? First of all,
0:39:23 > 0:39:26it is incredibly light and it's floating on the surface,
0:39:26 > 0:39:27but it's also reacting.
0:39:27 > 0:39:31I'm going to fish that out. It's very reactive indeed.
0:39:31 > 0:39:34I don't think lithium spoons are going to catch on at all, do you?
0:39:34 > 0:39:37- This is because it's just too reactive.- Too explosive.
0:39:37 > 0:39:40Exactly, thank you very much indeed.
0:39:40 > 0:39:43APPLAUSE
0:39:45 > 0:39:48A bit of coughing there just from the reaction
0:39:48 > 0:39:51as the lithium combines with the oxygen.
0:39:51 > 0:39:54It's reacting with the water vapour.
0:39:54 > 0:39:57COUGHING
0:39:57 > 0:40:03Yes, yes. Thank you. The lithium there, it floats on the surface.
0:40:03 > 0:40:08It is incredibly light but it's incredibly reactive as well.
0:40:08 > 0:40:11That may be the world's first lithium spoon
0:40:11 > 0:40:15but I think it's safe to say it's also going to be the world's last.
0:40:15 > 0:40:20It does show how reactive lithium is and maybe be can use this element
0:40:20 > 0:40:23to prepare new elements, and we can indeed.
0:40:23 > 0:40:29We have a reaction here to generate a new element from silicon dioxide.
0:40:29 > 0:40:33Does anyone know where we find silicon dioxide?
0:40:33 > 0:40:36Any ideas, right at the back?
0:40:36 > 0:40:38In sand, you're quite right.
0:40:38 > 0:40:42We find silicon dioxide, it is sand.
0:40:44 > 0:40:47We've got some lithium in here and some sand.
0:40:47 > 0:40:51We've mixed the two together, little lithium pelts and some sand,
0:40:51 > 0:40:56and I'm going to heat this up at the moment and see what happens.
0:40:56 > 0:40:58This is lithium with silicon dioxide
0:40:58 > 0:41:01and the silicon dioxide is a mineral, it's just sand.
0:41:01 > 0:41:04Quartz is the same stuff, silicon dioxide,
0:41:04 > 0:41:08so sand is smashed up pieces of quartz.
0:41:08 > 0:41:11I'm hoping that we should see a reaction take place
0:41:11 > 0:41:14and there we are.
0:41:14 > 0:41:17This is a very violent reaction again
0:41:17 > 0:41:21and this is as the lithium is stealing the oxygen away
0:41:21 > 0:41:24from the silicon dioxide that makes up the sand.
0:41:26 > 0:41:30Anyone have a guess at what we're going to make? Silicon, very good.
0:41:30 > 0:41:34We take the oxygen away from the silicon dioxide
0:41:34 > 0:41:38and we end up with silicon.
0:41:38 > 0:41:42Remarkably, this is a single crystal
0:41:42 > 0:41:46of a very purified silicon.
0:41:46 > 0:41:49It's very valuable and very precious
0:41:49 > 0:41:52and I need to put on some special gloves for this.
0:41:55 > 0:41:59It's hard, it's very solid.
0:41:59 > 0:42:04It's sort of like a metal and it's incredibly heavy.
0:42:04 > 0:42:08Actually, I can hardly lift this thing up,
0:42:08 > 0:42:11but it's grown in this very special way here.
0:42:11 > 0:42:13This is one crystal of silicon
0:42:13 > 0:42:16but it has a seam running all the way along the top here.
0:42:16 > 0:42:20This just proves that it is in fact one crystal.
0:42:20 > 0:42:22Why do people grow these?
0:42:22 > 0:42:26They grow them from the molten silicon.
0:42:26 > 0:42:28They would keep purifying it, heating it
0:42:28 > 0:42:32and allowing it to cool into this rather strange-looking shape.
0:42:32 > 0:42:35They do this because they're trying to make these,
0:42:35 > 0:42:39and this is a silicon wafer.
0:42:39 > 0:42:43It's just a sheet of silicon, just a slice from this,
0:42:43 > 0:42:48and these are used to make silicon chips.
0:42:48 > 0:42:52This is the same slice of silicon
0:42:52 > 0:42:58and then they're etching in and adding other reagents to this,
0:42:58 > 0:43:01gradually building up the silicon chips that we have
0:43:01 > 0:43:06in our mobile phones and in our computers.
0:43:09 > 0:43:12A fantastic use for this element, silicon.
0:43:12 > 0:43:16The element we extract from sand.
0:43:16 > 0:43:19Chemists are always finding new uses for the elements.
0:43:19 > 0:43:23Even though this has been known for well over 100 years,
0:43:23 > 0:43:27it is only relatively recently that we have found out
0:43:27 > 0:43:30how to use this element to make silicon chips.
0:43:30 > 0:43:31So far in the lecture,
0:43:31 > 0:43:34we swapped elements around to make different useful materials.
0:43:34 > 0:43:37We've stolen oxygen from iron oxide to make iron,
0:43:37 > 0:43:39and we've stolen it from sand.
0:43:39 > 0:43:42We've even rearranged the structures of carbon
0:43:42 > 0:43:45to turn graphite into diamond.
0:43:45 > 0:43:50What we still haven't done is turn one element into another.
0:43:50 > 0:43:53That's what the alchemists were trying to do,
0:43:53 > 0:43:55to turn lead into gold. Is this possible?
0:43:55 > 0:43:58Can we turn one element into another?
0:43:58 > 0:44:02Yes, this is the process of radioactivity,
0:44:02 > 0:44:07and this occurs deep in the Earth and indeed all around us.
0:44:07 > 0:44:10Can we have our periodic table up, please?
0:44:10 > 0:44:13Those of you, you elements who are radioactive,
0:44:13 > 0:44:15I'd like you to stand up, please.
0:44:15 > 0:44:19All the radioactive elements. That's all of this front row here.
0:44:19 > 0:44:21Yes, you're all radioactive.
0:44:21 > 0:44:24Bismuth, we're not sure about you, you're unknown,
0:44:24 > 0:44:26but actually you're so radioactive,
0:44:26 > 0:44:28you're no longer who you thought you were.
0:44:28 > 0:44:30You'd better sit down again. What does that mean?
0:44:30 > 0:44:32Why do you have to sit down again?
0:44:32 > 0:44:35It's because during radioactive decay,
0:44:35 > 0:44:39an element changes into another element.
0:44:39 > 0:44:42If we have cards down for a moment, please?
0:44:42 > 0:44:45Remember, what makes an element unique
0:44:45 > 0:44:48is the heart of the atom itself.
0:44:48 > 0:44:53That's the number of protons that it has within it.
0:44:53 > 0:44:56This represents what's inside an atom.
0:44:56 > 0:45:00This is its nucleus, and we have to count the number of the red spheres,
0:45:00 > 0:45:02these represent the protons,
0:45:02 > 0:45:04to work out what element this is.
0:45:04 > 0:45:07In fact, this is the element uranium.
0:45:07 > 0:45:12The thing about uranium is - oops - it's unstable,
0:45:12 > 0:45:14and bits drop off.
0:45:14 > 0:45:16The nucleus here just gets so large
0:45:16 > 0:45:21that it's very difficult for all these things to stay together
0:45:21 > 0:45:24and, yes, bits do drop off and when they drop off,
0:45:24 > 0:45:26it's changed into different element.
0:45:26 > 0:45:31It's the number of the red protons that define an element,
0:45:31 > 0:45:32so if we lose two,
0:45:32 > 0:45:36it's no longer what we thought it was to start off with.
0:45:36 > 0:45:39Can we find uranium in our periodic table. Where's uranium?
0:45:39 > 0:45:44Would you like to stand up?
0:45:44 > 0:45:48Uranium, you are radioactive, and bits do drop off.
0:45:48 > 0:45:51Quite slowly, don't worry, we won't notice.
0:45:51 > 0:45:54But actually when it does happen, when it does fall off,
0:45:54 > 0:45:56you change into a different element
0:45:56 > 0:45:58and you move a couple of spaces along.
0:45:58 > 0:46:01You become thorium, so maybe you should move over to thorium.
0:46:01 > 0:46:06Better put your card down because you're not "U" any more. Get it?
0:46:06 > 0:46:09You're no longer you, you're actually thorium.
0:46:09 > 0:46:13You'd better go over there, you are on thorium's space now.
0:46:13 > 0:46:17Actually, both thorium and uranium have also decayed,
0:46:17 > 0:46:21and if you decay now, you're going to become the element radon.
0:46:21 > 0:46:25You're also radioactive, I'm afraid, so if you decay,
0:46:25 > 0:46:28you lose a couple of protons in an alpha particle.
0:46:28 > 0:46:32You're not radon any more, you've become polonium.
0:46:32 > 0:46:34Can we see this in action?
0:46:34 > 0:46:38We can, using this apparatus here.
0:46:38 > 0:46:41This is known as a cloud chamber.
0:46:41 > 0:46:49The tank that we see here contains an atmosphere of alcohol vapour
0:46:49 > 0:46:51and it's got a lot of vapour in there
0:46:51 > 0:46:55and it's actually trying to form little droplets.
0:46:55 > 0:46:56There's a temperature gradient.
0:46:56 > 0:47:00There's a little heating wire at the top and it's cooled down
0:47:00 > 0:47:02from underneath, so it's gradually freezing.
0:47:02 > 0:47:06It wants to form droplets but actually it's much easier
0:47:06 > 0:47:09if there's something there to help it.
0:47:09 > 0:47:12Any charged particles can cause this.
0:47:12 > 0:47:15All the tracks that you can see now,
0:47:15 > 0:47:18all these little wispy white trails,
0:47:18 > 0:47:23are actually particles of radiation.
0:47:23 > 0:47:27This is natural radiation just in the air around us.
0:47:27 > 0:47:31We don't tend to think of radioactivity as being very natural,
0:47:31 > 0:47:34but of course, we're all weakly radioactive
0:47:34 > 0:47:36because of some of the radioactive elements in us.
0:47:36 > 0:47:42Here, we can see radiation in action here just in the air around us.
0:47:42 > 0:47:48I'm going to introduce into this a sample of a radioactive element
0:47:48 > 0:47:51called americium.
0:47:51 > 0:47:56Look at that. You can see the tracks forming here.
0:48:00 > 0:48:06Each little track that we see is the result of a charged particle
0:48:06 > 0:48:11being emitted from the element americium
0:48:11 > 0:48:16and the particles emitted are alpha particles.
0:48:16 > 0:48:20The alpha particle is two protons, two neutrons,
0:48:20 > 0:48:25and actually that is the heart of an atom of helium.
0:48:25 > 0:48:31What we're actually seeing here is the birth of helium atoms,
0:48:31 > 0:48:36which I think is quite remarkable. I'll just put this away.
0:48:36 > 0:48:41It is possible then to change one atom into another.
0:48:41 > 0:48:45Nature seems to do this, but can we?
0:48:45 > 0:48:47Actually, it is possible,
0:48:47 > 0:48:50and one of the first people to generate lots of different atoms
0:48:50 > 0:48:53was this chap here, Glenn Seaborg.
0:48:53 > 0:48:58In fact, he even has an element named after him.
0:48:58 > 0:49:00Where's seaborgium? There we are,
0:49:00 > 0:49:02right in the middle of the periodic table.
0:49:02 > 0:49:07In 1980, Seaborg did an amazing experiment.
0:49:07 > 0:49:12He took bismuth and he turned it into gold.
0:49:12 > 0:49:15This is what the alchemists had been dreaming of.
0:49:15 > 0:49:17He changed one element into gold.
0:49:17 > 0:49:19What he did was take bismuth -
0:49:19 > 0:49:22can we have our periodic table up for a second, please?
0:49:22 > 0:49:27He took the element bismuth and he fired atoms of carbon and neon
0:49:27 > 0:49:31at this and it knocked out a number of protons
0:49:31 > 0:49:34until we ended up with gold.
0:49:34 > 0:49:38Unfortunately, he only ended up with the few thousand atoms
0:49:38 > 0:49:40and this is not enough to get him rich.
0:49:40 > 0:49:44It was a very expensive experiment, took a lot of money to get this
0:49:44 > 0:49:48and all he made was a few atoms, but it is possible to do it.
0:49:48 > 0:49:52Radioactivity is a natural process but it can also be brought about
0:49:52 > 0:49:55by firing one atom at another,
0:49:55 > 0:49:59and changing it and creating new, heavier elements
0:49:59 > 0:50:01or even to make gold.
0:50:01 > 0:50:02Do we even want to make gold?
0:50:02 > 0:50:05Are there other things that fascinated the alchemists
0:50:05 > 0:50:08which modern scientists have taken one step further?
0:50:08 > 0:50:11This is another naturally occurring rock
0:50:11 > 0:50:14that has really quite remarkable properties.
0:50:14 > 0:50:18This one amazed the early alchemists.
0:50:18 > 0:50:19I'll show you why.
0:50:19 > 0:50:23Over here, our audience members have some paper clips.
0:50:23 > 0:50:26Have you got some paper clips?
0:50:26 > 0:50:30I'd like you to put your paper clips onto here, just onto the rock.
0:50:32 > 0:50:35They should stick by themselves.
0:50:35 > 0:50:39It's not a surprise to us because we've all seen magnets before,
0:50:39 > 0:50:43but just imagine if you were the first person to ever see a magnet.
0:50:43 > 0:50:46I have a book here from the 1530s
0:50:46 > 0:50:50that describes this magnetic rock, this lodestone.
0:50:50 > 0:50:53They really did find it quite remarkable.
0:50:53 > 0:50:56This here shows this magnetic rock.
0:50:56 > 0:51:02There's a ship sailing past a mountain that's supposedly made
0:51:02 > 0:51:05of this lodestone, this magnetic ore.
0:51:05 > 0:51:09You can see here, these are the nails from the ship.
0:51:09 > 0:51:13They've supposedly been sucked out of the ship, so this is
0:51:13 > 0:51:17a sort of warning that there's this incredibly strange magical material
0:51:17 > 0:51:21with these amazing properties which would suck the nails
0:51:21 > 0:51:24out of your ship and you'd be shipwrecked.
0:51:24 > 0:51:28There's a warning for you. OK, thank you.
0:51:28 > 0:51:34Nowadays, scientists have learned how to make even stronger magnets
0:51:34 > 0:51:37from the elements, and if we just have our periodic table up again,
0:51:37 > 0:51:45some of the strongest magnets now made use the element neodymium.
0:51:45 > 0:51:48Give us a wave, up there, very good.
0:51:48 > 0:51:53The strongest magnets in the world are made with neodymium.
0:51:53 > 0:51:55This element was discovered in the 1880s,
0:51:55 > 0:52:00but it was over 100 years later that scientists learnt how to use
0:52:00 > 0:52:03this element to create these magnets.
0:52:03 > 0:52:05Thank you very much, periodic table.
0:52:05 > 0:52:07I have a couple of these magnets here
0:52:07 > 0:52:10and they really are very strong indeed.
0:52:10 > 0:52:12These are little neodymium magnets.
0:52:12 > 0:52:16Here we are, just try to pull these apart?
0:52:16 > 0:52:18I can't. Are they stuck together?
0:52:18 > 0:52:21No, they're not stuck together. Try again.
0:52:21 > 0:52:25Give them to your neighbour, see if he can get them?
0:52:25 > 0:52:27- Can you pull those apart?- No.
0:52:27 > 0:52:30I promise you they're not stuck together.
0:52:30 > 0:52:35I could probably slide them or something if I push. Look at that.
0:52:35 > 0:52:38They're very strong magnets indeed.
0:52:38 > 0:52:42Even though the element neodymium has been known for over 100 years,
0:52:42 > 0:52:46these magnets have only recently been developed.
0:52:46 > 0:52:48Now, these really are quite strong
0:52:48 > 0:52:54and I think to show just how strong these are, I need another volunteer.
0:52:54 > 0:52:57I think we should have one from this side.
0:52:57 > 0:53:01Would you like to come down to the front, please?
0:53:01 > 0:53:05APPLAUSE
0:53:05 > 0:53:08OK, very good. Are you feeling strong? You are, that's good.
0:53:08 > 0:53:11- Tell us your name, please. - Marie.- Marie.
0:53:11 > 0:53:15We're just going to bring down this rig here.
0:53:15 > 0:53:18We're going to suspend you from the ceiling
0:53:18 > 0:53:22using this little magnet here. That's the only magnet.
0:53:22 > 0:53:25This is a block of iron. It's not magnetic.
0:53:25 > 0:53:27I can show that with a paper clip,
0:53:27 > 0:53:30just holding the paper clip, it stays on it
0:53:30 > 0:53:32but it's not attracted to it.
0:53:32 > 0:53:33This is our magnet.
0:53:33 > 0:53:37I'm not going to put the paper clip on this, I'd never get it off again.
0:53:37 > 0:53:39If you'd like to come over here, please.
0:53:39 > 0:53:42I just need to very carefully put this in the middle. Perfect.
0:53:42 > 0:53:46Just clip this on as well.
0:53:46 > 0:53:50OK, so you're feeling strong?
0:53:50 > 0:53:54If you just hold on to here. That's it.
0:53:54 > 0:53:57Can you just raise up the winch then, please?
0:53:57 > 0:54:01Hold on strong, hold on tightly and we'll just see if we can lift you
0:54:01 > 0:54:03off the ground so you need to hold on very tightly.
0:54:03 > 0:54:05Might need to move forward a little bit.
0:54:05 > 0:54:08Keep holding on and just watch the feet.
0:54:08 > 0:54:10There we are, look at that!
0:54:10 > 0:54:14You are now suspended from the ceiling. That's fantastic!
0:54:14 > 0:54:16APPLAUSE
0:54:19 > 0:54:21It really is pretty strong magnets there.
0:54:21 > 0:54:23We can actually hang from them.
0:54:23 > 0:54:26It's just using the power of these new magnets
0:54:26 > 0:54:30but these are incredibly useful and they find uses for instance
0:54:30 > 0:54:35in turbines, but are also used in electric cars and so on as well.
0:54:35 > 0:54:38These new materials - very, very useful.
0:54:38 > 0:54:42We can create even more amazing materials using the elements.
0:54:42 > 0:54:45Can we just have our periodic table up for a moment?
0:54:45 > 0:54:47We were using magnets there to suspend
0:54:47 > 0:54:50and these were the neodymium magnets,
0:54:50 > 0:54:53but this, we're going to use some superconductors
0:54:53 > 0:54:57and the superconductors are made from the elements yttrium,
0:54:57 > 0:55:00just here. Give us a wave, yttrium.
0:55:00 > 0:55:05And from barium, so give us a wave, barium. Very good.
0:55:05 > 0:55:08And copper. OK, there's copper,
0:55:08 > 0:55:11and oxygen at the top there.
0:55:11 > 0:55:16Put you four elements together and we get these amazing materials -
0:55:16 > 0:55:18high-temperature superconductors.
0:55:18 > 0:55:22This is called a Mobius strip. It's a rather strange looking thing.
0:55:22 > 0:55:26- How many sides has this got?- Two. - Well, you'd think so.
0:55:26 > 0:55:30Actually, if you start here and you keep on going round,
0:55:30 > 0:55:33you actually come back underneath.
0:55:33 > 0:55:37If you keep going round, you come back where you started from.
0:55:37 > 0:55:40It actually has one side, this mathematical shape,
0:55:40 > 0:55:41which is very unusual.
0:55:41 > 0:55:45I can show you this using our little superconductor.
0:55:45 > 0:55:49This Mobius strip is covered with these neodymium magnets,
0:55:49 > 0:55:53these very strong magnets. We've got a superconductor here
0:55:53 > 0:55:55and this is the superconductor
0:55:55 > 0:56:01that's made from the barium, the yttrium, the copper and the oxygen.
0:56:01 > 0:56:04This is the ceramic there. This is this disc in the centre.
0:56:04 > 0:56:07We are cooling it with liquid nitrogen
0:56:07 > 0:56:10in this little holding tray on the top.
0:56:10 > 0:56:12It levitates quite nicely.
0:56:17 > 0:56:22There we are, it's come back to where it was.
0:56:22 > 0:56:26Now it's actually hanging underneath this strip,
0:56:26 > 0:56:27but it needs to be cooled down
0:56:27 > 0:56:29so we are cooling it with liquid nitrogen.
0:56:29 > 0:56:33That's in order to enable these superconductors to work.
0:56:33 > 0:56:36They only work at these very low temperatures,
0:56:36 > 0:56:39so eventually it's going to warm up and it will fall off the track
0:56:39 > 0:56:43so you need to catch it when it does fall.
0:56:43 > 0:56:45You're meant to catch it!
0:56:45 > 0:56:48Just pass it to me straight away, thank you. That's lovely.
0:56:50 > 0:56:53Thank you very much. Thank you for all your help there.
0:56:53 > 0:56:56APPLAUSE
0:57:03 > 0:57:07Really quite remarkable properties then of this ceramic
0:57:07 > 0:57:11made out of the elements barium, yttrium, copper and oxygen.
0:57:11 > 0:57:14We've come a long way since the days of the alchemists
0:57:14 > 0:57:19when the whole world could be made from air, water, earth and fire.
0:57:19 > 0:57:21I hope you've enjoyed our quest to discover
0:57:21 > 0:57:24what's really making up the world around us.
0:57:24 > 0:57:27If you remember one thing from these lectures,
0:57:27 > 0:57:30it's that the work of the chemist is not complete.
0:57:30 > 0:57:33New combinations are being discovered all the time
0:57:33 > 0:57:37and nobody knows what exciting properties they may have.
0:57:37 > 0:57:39I'd like everyone to pick up your cards one last time
0:57:39 > 0:57:42and have a look at your card.
0:57:42 > 0:57:46Just remember what element you've got, and I want you to go home
0:57:46 > 0:57:48and research about your element
0:57:48 > 0:57:51and think what uses can we put this element to,
0:57:51 > 0:57:55and what new possibilities could there be? Who knows?
0:57:55 > 0:57:58You may be able to solve some of the challenges of the future
0:57:58 > 0:58:02and maybe even make something more valuable than gold.
0:58:02 > 0:58:04Thank you and goodnight.
0:58:04 > 0:58:06APPLAUSE
0:58:09 > 0:58:12Subtitles by Red Bee Media Ltd