Original subtitles

Gold. This is what alchemists dreams were made of.

The medieval thinkers spent their lives trying to find a way

to turn cheap metals, such as this lead, into gold.

Success would bring them fame and infinite fortune,

but is such magic even possible?

Join us in the search for the philosopher's stone.

APPLAUSE

The alchemists were obsessed with the idea of producing

a philosopher's stone.

A magical rock or powder that could turn metals into gold.

There are even stories of espionage, kidnap and even murder

in a bid to steal the secret of the stone.

But what about the gold I just made?

Well, I'm afraid we cheated.

I'm not an alchemist. My name is Dr Peter Wothers

and I'm a chemist from the University of Cambridge.

I did start with lead.

It was a specially prepared form of lead that reacts

with the oxygen from the air to give this beautiful lead oxide.

This yellowy orange compound here.

So we did cheat here.

And my philosopher's stone, well,

it was just a hot coal which started this reaction.

Some alchemists used this reaction to try to convince people

that they could make gold. But is such a feat even possible?

In the last of this year's Royal Institution Christmas lectures,

I hope to find out.

In the previous lectures,

we've looked at the elements in the air, and water, and now we are

going to look at the elements in the earth and how we can extract them.

How we can use them and whether we can turn one into another.

To help me, I have a giant periodic table made up

of members from the audience here at the Royal Institution.

Let's just look at the elements we have already talked about.

We have lead, can you stand up, please, lead? Thank you.

We were looking at you

and you were reacting with the oxygen from the air.

Can you stand up please, oxygen? OK.

This is how we normally find our metals in the earth.

We don't find them lying around,

they are normally combined with the oxygen from the air.

Or maybe sulphur, or occasionally other metals. Thank you very much.

If we put our periodic tables down now, please.

But occasionally, we can find metals just lying around.

The classic case is gold. Where are you, gold?

You are so special because sometimes you can be found just lying around.

In fact, here's a piece of you here. This is a gold nugget.

Thank you, periodic table, at ease.

This is pure gold. And it can be found like this in nature.

In fact, this is how it is normally found.

Now the remarkable thing about gold is that it doesn't change over time.

So you could leave it for tens, hundreds, even thousands

of years and it'll still have this beautiful appearance.

I've got a very old piece of gold to show you now.

Would you please welcome, from the Museum of London, Meriel Jeater.

APPLAUSE

I gather that this is a piece of local gold, is that right?

Exactly, yes. It was found in London, in Cannon Street in 1976.

It's actually a Roman gold and emerald necklace. That's beautiful.

This is pure gold wire running through these emeralds?

That's right, yes. And you say this is from the early Roman times?

This is how old? Nearly 2,000 years old, yes. 2,000 years old.

Has this been heavily restored?

It's been given a bit of a clean to get the mud off.

Just the mud off and the gold itself was looking just like this? Exactly.

That's why it's so wonderful for archaeologists. Exactly.

For me as a chemist, I think it's incredible that you can find

gold in this state and it doesn't tarnish over time.

It doesn't combine with oxygen or water or anything.

This is how you find it.

You can see that clearly it was highly prized

and I think maybe you should take it back to the museum.

Thank you very much. Pleasure. Big round of applause, please.

APPLAUSE

This has lasted so well because it was so highly prized,

so valued there but also because it didn't change over time.

But, of course, we have a saying about the value of gold.

Sometimes people are told, "You're worth your weight in gold."

Have you ever been told you're worth your weight in gold? Yeah.

Oh, you have! Oh, good. Who told you that?

I can't remember. Probably a parent.

Maybe we should ask gold. Where's gold sitting? Are you gold, yes?

Have you been told that you're worth your weight in gold before?

I think my parents... They've told you this, have they?

I think we should see just how much gold that would be.

Would you like to come down to the front, please?

APPLAUSE

Would you like to face the front here.

Would you like to tell everyone your name? Emma.

Take a seat on here.

If you just carefully sit down on there. That's beautiful, lovely job.

OK, right, are you sitting comfortably?

Yep. Then we'll begin. This is where I get very excited.

This is all real gold. And it's pretty good stuff, actually.

Have you ever held a big block of gold before?

No. No. Well, have a feel of this.

That is pretty exciting, isn't it? Would you like to feel this as well?

I'm afraid I can't let everybody have...

I know, it's amazing, isn't it?

This is actually about the same as six large bottles of fizzy pop.

I'm just going to put this on here.

OK, I think you need more than that. Let's keep going.

Let's put this one on. It really is pretty good stuff, this.

This is 24ct pure gold.

And this one here.

More. More still.

Not quite. No. OK, let's try this one.

I think it's almost level but not quite.

I think we need just a little bit more.

Has anyone else in the audience got any gold?

LAUGHTER

I found some on the way in.

Oh, you've got some?

Isn't that Nobel prize-winning chemist Prof Sir Harry Kroto?

I think it is.

APPLAUSE

So what exactly...I think I might know what this is.

Is this really your Nobel Prize? Yes, they give them away.

This is solid gold, isn't it? It's solid gold. And I want it back.

Well, of course, Harry. I trust you. Oh, thank you.

Right, anyway, maybe this is just what we need.

Let's just try that on there.

Oh, I think that's pretty well balanced now.

I think that's quite amazing.

I think that is 43kg of gold and one Nobel Prize.

Thank you very much. Big round of applause.

Stay where you are for a moment.

APPLAUSE

Thank you, Prof Kroto, for saving the day. This is quite amazing.

43kg, but it doesn't actually look too much there, does it, Emma?

What do you think?

As you say, it's very dense

and this is why it doesn't actually take up much space.

If you were made of gold, you would weigh 800kg,

which is about as much as a small car.

Which is quite a lot really, isn't it? So that's pretty impressive.

How much do you think this is worth? How much do you think? Have a guess.

Um...quite a lot.

I think you're right there. Quite a lot, yes.

Anyone have any other ideas? Shout it out. Yes?

One million? One million, actually, you're not far off.

It is even more than that.

This is about £1.5 million worth of gold just sitting here.

Which is pretty impressive, isn't it? All right, now.

If you just stay where you are sitting, please.

I need to unload this first of all. I'll just take that and...

LAUGHTER

Just going to put these over here.

A few little bits left.

There we are. That's fantastic. OK, thank you very much, Emma.

Big round of applause.

APPLAUSE

Gold really is an incredibly dense substance.

But actually, it's not the densest element.

Could we just have cards up for a second, please?

That honour goes to osmium. You are the densest thing in the universe.

Well, at least on Earth. Did you know that?

I don't mean that in a bad way. This is just you as an element.

Osmium is incredibly dense indeed.

Can we just keep the cards up for the people in the same row

as osmium and gold. Everyone else down.

Caesium stay up, barium stay up. All the way over to mercury.

Why is it, then, that these elements are so incredibly dense?

The most dense element is osmium, closely followed by iridium.

Well, atoms after osmium, iridium, gold,

all these other ones are getting heavier.

So the atoms themselves are heavier

and yet these ones are the most tightly packed.

So it's not just to do with how heavy the atoms are.

We also need to look at the bonding that we have between them.

And this is what we can see in the graph here.

This shows how much energy we need to put in to separate

a certain number of atoms of these elements.

And we see that we've got a peak around tungsten.

This is why we use tungsten in light bulb filaments,

because it's very difficult to pull them apart.

And we have very high temperatures.

But as we go beyond tungsten, the bonding isn't quite so strong

but the atoms are getting heavier.

And so it's bit of a balance between the strength of the bonds,

how tightly they are packed, and how heavy the atoms are.

This is why we reach a maximum for osmium and iridium.

Gold, platinum and so on are still very dense afterwards,

but the maximum is there for osmium and iridium.

So osmium is even more expensive than gold, in fact.

And if someone was really going to pay you a compliment

they would say, "You are worth your weight in osmium."

Actually, these metals are not the only precious things

we can extract from the earth.

There are even non-metals that we can sometimes find as well.

Hello. Hello, Prof Kroto.

I'm assuming you would like your Nobel Prize, would you?

I'd swap it for those bigger ones. Yes, so would I, I think.

Well, there we go. Thank you very much.

Perhaps you could tell us what you won the Nobel Prize for.

It's for discovering an alternative to these.

This is graphite and this is diamond. These structures.

These are actually the only ones that I knew about

when I was at school.

In the text books, there were just two types of carbon.

Two different forms called allotropes.

One has this arrangement. This one is the graphite.

This is the sort of thing you find in your pencils.

It's pretty soft and well, carbon, it's just an arrangement of carbon.

Diamond looks very different though, doesn't it?

I don't suppose...you've very kindly lent us your gold,

I don't suppose you have a spare diamond on you, do you?

I don't myself but my wife actually has one.

A-ha! You don't want to take that as well, do you? Well, just borrow it.

I hope I get it back. Thank you, Mrs Kroto. Of course, yes.

You can trust me.

This is a beautiful ring here. Is it an engagement ring or something?

It's really quite lovely.

The diamond comes out quite easily, doesn't it? Yes.

LAUGHTER

We can see it more clearly now. Look at that. It's beautiful.

What a beautiful diamond. It is a real diamond though, is it?

It as real as you can get. It's quite stunning.

Of course, we want to show that this graphite is made up of carbon.

There is one way we can do this.

We can burn our carbon in oxygen and we'll get, what would we get?

Carbon dioxide. See? He's pretty good. Carbon dioxide.

And then if we bubble that through lime water? Calcium carbonate.

Calcium carbonate. That's the test for carbon dioxide, of course.

And it would be white. I didn't ask you that one.

You are getting carried away now. Let's just see this over here.

We have some apparatus.

This is where we are going to burn some graphite

and show that it is made of carbon.

What's bubbling through here is just oxygen.

This won't react with our lime water at all.

We are going to see if we can light the graphite

and get it burning inside the oxygen. There we are. Thank you.

That's great. So now we have a hydrogen flame.

This won't produce anything. It's only going to produce water.

You can see the water just beginning to condense.

Beautiful. I'm going to turn the flame off.

Look at that. What do you think? It's brilliant.

It is literally brilliant, yes.

This is the carbon combining with oxygen that's flowing through here.

Hopefully, we are going to see this changing colour, giving us

a milky colour. Showing that there is carbon dioxide present.

I think we should test diamond as well, don't you? What do you think?

ALL: Yes!

Yes? Does Mrs Kroto mind?

OK. In the name of science. That's very kind of you.

Harry seems a little nervous. Are you sure this is a real diamond?

I think it's a real diamond, yes. Let's give it a go then.

We will just put it on there. And again, we'll put this on here.

Right, so we have our flame. Here we go. The moment of truth.

Now can we get our diamond to burn in the oxygen?

WATER BUBBLES

Ah, look at that!

I hope you can afford to pay for this.

The good news is, Harry, it is a real diamond.

LAUGHTER

OK.

I think this is absolutely stunning.

That diamond there, it is burning in oxygen.

It's combining with the oxygen of the air.

Have you ever seen a diamond burning like that before? No, I haven't.

It is quite stunning to see. That's right.

There are no flames coming from this.

So this is just the heat of the reaction as the carbon combines

with the oxygen that's present, flowing through here,

forming carbon dioxide. That is absolutely stunning.

Just look at that. It's glowing all by itself.

It's absolutely brilliant. I think that's amazing.

And look, our lime water is going milky.

It's the most expensive lime water I've ever seen.

I think you are probably right there.

It really is the most expensive lime water you've ever seen.

Well, we are waiting for your diamond just to... Disappear.

To disappear, yes.

Maybe you could tell us about your Nobel Prize again.

I think it has something to do with this. I think it does, yes.

Would you like to come round to the front, actually.

We'll compare it to these ones.

This one was the graphite. This is the diamond.

And this is the third form, the well-characterised form.

It consists of 60 carbon atoms in the shape of a soccer ball.

And it was such a fantastic surprise when we discovered it.

One of the clues to its structure was Mr Fuller's geodesic domes.

In Montreal, we had visited that. And I remembered it.

It was in a book of mine

and when we were trying to work out how a sheet of graphite like this,

or a graphing sheet, might close up,

what we discovered was, it could close up if it had 12 pentagons.

You cannot close a sheet of hexagons up. It won't close up.

But if you have 12 pentagons, it will.

And you are all familiar with that in the case of the normal

soccer ball with 12 black pentagons and 20 hexagons.

And that's the magic that Mr Fuller knew, and other people as well.

And I called it Buckminsterfullerene

because there are double bonds as there are in benzene.

So the "ene" ending was just a beautiful sort of ending

to a great name.

So since my time at school, the textbooks have to be rewritten

with a new form of carbon discovered by this chap here.

And colleagues in the States. And your co-workers in the States.

We should have another look at your diamond here.

It seems to have decreased in size.

I think we should come clean.

Don't worry, we didn't destroy Mrs Kroto's engagement ring.

That really would be quite harsh. This is a pretty low-grade diamond.

It still looks pretty good to the naked eye

but the experts say it's not very valuable at all.

But it is a real diamond.

And it is combining with oxygen

and I think that's a pretty stunning reaction. Thank you, Prof Kroto.

It's a real privilege to have a Nobel Prize winner here,

helping out with an experiment. Thank you very much.

APPLAUSE

So is it possible that we could take this worthless carbon dioxide

and get our diamond back from that?

I mean, that really would be the alchemist's dream.

Recovering something precious from something worthless.

We've got a demonstration here that shows that this may be possible.

I'll just turn this round.

Now this tank is filled with carbon dioxide gas.

We've put some solid carbon dioxide in the bottom,

which is slowly evaporating, turning into the gas.

We can't see the gas because, of course, it's colourless.

But it is there. How can we test for this?

Does anyone know another use for carbon dioxide? Yes?

To put out flames. To put out flames, yes, exactly.

I wonder if we have a flame, please. Is there a flame anywhere?

Ah, yes. Here is a flame that certainly needs putting out.

If I just lower this into the tank...

There we are. You can see that it goes out.

This is because, of course, the tank is filled with carbon dioxide.

And carbon dioxide doesn't support combustion.

Right, now then. We have also placed in this tank some magnesium metal.

I'm just going to fish this out.

This is a little nest of magnesium metal.

I'm going to light the magnesium here

and it burns with a brilliant white flame. There we are.

Now I'm going to lower this into the carbon dioxide.

It seems to be burning even more vigorously now.

The flame is still burning.

But what about this? This one...well, this one still goes out.

Our petrol is extinguished in the carbon dioxide,

but the magnesium is reacting with it.

The magnesium is stealing the oxygen away from the carbon dioxide

and, well, we'll have a look at what we've got at the bottom

but let me take this out. You can see magnesium oxide

covered over what was the magnesium here,

but look in the centre. What we've now got is black carbon.

The magnesium removes the oxygen leaving behind the carbon

from the carbon dioxide.

We can get our carbon back from carbon dioxide

but, well, it's not a diamond yet.

Is it possible to turn that carbon into a diamond?

Well, actually, this is what happens deep within the earth,

and this is a diamond in a rock

just as it would have come out of the earth.

This is really quite beautiful indeed.

Deep within the earth, the carbon is heated up

and compressed with huge temperatures, huge pressures,

and the carbon we saw there, the black carbon,

is converted into diamond.

Recently, chemists have learnt how to copy this process,

how to turn graphite or other forms of carbon into diamond.

I'd like a volunteer to help me out with this one, please.

Would you like to come down to the front, please?

APPLAUSE

If you'd like to come down to the front. Your name is...?

Lewis. Lewis, OK. Now, this is a diamond.

Would you like to just hold this?

What do you think, are you impressed? Yeah.

Looks like a piece of glass, doesn't it? It actually really is a diamond.

This is a synthetically grown diamond and this has been prepared

not from the high temperature, high pressure system that we also use,

this is a technique called chemical vapour deposition

where the diamond is gradually built up a layer at a time.

I'd like you to take this, not keep it, but bring it over here

and just place it on top.

This is some ice here. Hold it like this.

Just put that on top of there and push through this ice.

How does that feel? Cold. It feels very cold and what's happening?

Water's coming off.

This is ice, solid ice, and it seems to be going...

You've chopped all the way through this quite cleanly there.

As you say, it's got very cold.

Do you know why it's got colder? No idea.

It's used your energy to heat up this block of ice,

so yes, you're getting cold because it's taking the energy

from your fingers here. Let's try this again.

If I just put this on here, it slices through like butter.

It's really quite amazing. It feels very strange.

I'm not sawing. It's not cutting because it's hard,

it's cutting because it's a very good conductor of heat.

Quite remarkable, so cleanly through this block of ice.

Feels very strange. Thank you very much, thank you for that.

APPLAUSE

That remarkable property of diamond

was because it's an incredible conductor of heat.

To demonstrate this and explain why this is so,

I'd like some other volunteers, please.

I'd like six people so if we could have all of you, six of you,

if you could come down to the front, please?

In a row, facing the audience. Sit next to each other.

I'd like all of you to face that direction, please,

turn around and face that way.

Just close up a little bit, a little bit friendlier.

Come this way, please. Lovely job. Close up there

and put your hands on the shoulders of the person in front.

Face that way. That's good.

Now, at the moment, these are all pretty weak bonds here.

Watch what happens when I give a bit of energy this way.

Don't do anything, just behave normally.

Lucy, can you feel anything?

It was very difficult to get this energy through there

and this is because of all these weak bonds.

What I'd like you to do is just spread yourselves out a little more

and hold arms with very rigid arms.

Rigid, straight arms. That's it.

Now I'm just going to do the same thing again.

Give you a jolt that end and now you can see you're certainly moving.

Thank you very much indeed, thank you for all your help.

APPLAUSE

This is why our diamond is such a good conductor of thermal energy.

It's because the bonds are so strong holding these carbon atoms together,

they're so rigid, that this energy is very easily transmitted through.

Diamond is the best conductor of heat of any substance known,

until very recently when scientists discovered a new form of carbon,

another form, called graphene, which is a single sheet of graphite.

That is an even better conductor of heat. They're the best ones known.

We've seen then that we can convert charcoal,

we convert graphite into diamond under very high pressures

or using the other technique of chemical vapour deposition.

Surely if the alchemists had focused on that, they would have changed

their attention away from trying to turn base metals into gold.

But of course, they were focused on metals because metals

were incredibly important and still are very important.

It's only gold that has this unique property

that we can find it lying around. Most metals we find in their ores.

Ores like this here.

This is the natural mineral - does anybody know what it is?

It is an iron ore.

Does anyone know what the name of the iron ore would be?

Very good, you're doing well. Hematite it is.

This is the mineral hematite.

This is now our source for iron

but it's locked up with the iron combined with oxygen.

Somehow we have to learn how to extract the metal out of this.

After all, it doesn't just fall from the skies.

But remarkably, sometimes it does just fall from the skies

and this is what we have here.

This is actually very heavy as well.

This is a lump of iron that did fall from the skies about 5,000 years ago

and it landed in Australia. Look at this.

What I wanted to show you here was the comparison

between these two pieces.

We can see that this is developing this reddish-brown colour,

the same as the hematite.

This contains iron. It is a slice of iron

but it is gradually combining with oxygen

to form this mineral hematite.

We can show that it is a meteorite

if we were to take a slice through this.

If we took a slice through this,

what we would see is something like this.

This is a slice through a meteorite and it's really quite beautiful.

This has been cut and we can see the side here.

This is the outer surface of the meteorite

and here it's been cut with this incredible pattern here.

This pattern has been etched with acid.

It etches away certain types of the minerals that are in here.

The forms of the iron, it etches away certain of them

and it reveals this beautiful crystal structure

and this proves that it's a meteorite,

because it's impossible to get this pattern here on Earth.

That's because we need to cool down molten iron

with a little bit of nickel in.

We'd need to cool it down over such a slow rate,

just one degree over thousands of years,

if we wanted to see these crystals develop.

This really is quite stunning indeed.

Over time, the metal of this beautiful meteorite

will turn into this ore here.

We can't wait thousands of years to see that

but we can speed this process up

and we can show how iron combines with the oxygen to form iron oxide.

I'd like a volunteer for this one, please.

I'd like someone from this side, who shall we have?

Would you like to come down to the front, please?

APPLAUSE

Would you like to tell us your name, please? Rose.

Rose, OK, we have some iron over here. This is just iron wool.

Would you like to feel this?

It's just the sort of thing you would use to clean your pots

and pans if you're helping out at home.

Now, I'll put on my goggles

and we're going to combine this with some oxygen.

We want to see how much this weighs by itself. This weighs 15.9 grams.

Now, the question is, what will happen

when this combines with the oxygen from the air?

How do you think its mass will change?

Will it go up, go down, stay the same?

What do you think, when it burns?

It will go up? It will go up, and why's that?

Because it will become more dense. It will become more dense.

Let's have a look and see, shall we?

I'm just going to apply a light here.

This beautiful reaction is the iron combining with the oxygen

and look what's happened to the mass.

It's gone down. It's getting lower.

-0.16, so whoever said it goes down, you're quite right.

But look now what's happening. It's going up again.

It's is getting heavier so whoever said it goes up, you're quite right.

Everyone's right, that's good. Why did it go down?

It went down initially because this iron wool was treated with oil,

just to try and stop it combining with the oxygen from the air.

Once this reaction has started, it is combining with oxygen

and that's why it's getting heavier. You were quite right.

It is getting heavier because the iron is forming iron oxide.

Thank you very much indeed.

APPLAUSE

Iron is pretty reactive stuff.

It reacts with oxygen and this is how

we would normally find our metal, combined with oxygen.

What about if you couldn't extract the iron from this?

What about before we knew how to do this?

The only iron that we would have had would have been iron

from a natural source such as this meteorite.

This sort of iron was used to make tools and so on.

I think we have an example of a tool using some natural iron here.

Would you please welcome Dr Caroline Smith

from the Natural History Museum.

APPLAUSE

This is really beautiful. What exactly is this?

This is an Inuit knife and it's made of walrus tusk,

so walrus ivory, but in the end you can hopefully see

it actually has an iron blade.

When this was discovered, the Inuits hadn't yet learnt

how to make iron, how to extract it from the ore.

That's right. They had to have a source of metallic iron.

At the time, it was thought that the iron in this knife

was actually from a meteorite called the Cape York meteorite,

a very large meteorite which was found in Greenland.

This knife actually came from Greenland,

but we're not actually sure that's right, now,

we think it might be from somewhere else.

I gather that you've performed an analysis on this

and more research suggests that you are beginning to question

whether this is a meteorite, but it has to be naturally occurring

because they didn't have the technology.

Exactly. They didn't have the technology to extract iron

from things like hematite so they had to have a source

of native iron, metallic iron.

We think now that maybe this is actually from a place

called Disko Island,

which is an island off the west coast of Greenland,

and it's one of the very few locations on earth

where you get metallic iron existing in metallic form.

You very kindly brought a couple of samples for us.

These are from Disko Island.

They look quite different but this one clearly looks very metallic.

You can see this here, it's got quite a shine to it.

It's quite a heavy specimen. It is very heavy.

This looks like a piece of iron but this is naturally occurring iron?

This is naturally occurring iron found at the surface of the Earth.

In fact, tons of this iron has been found.

But why hasn't this one corroded into the hematite?

What we think happened is that about 55 million years ago,

lava was erupted in this place, in Disko Island,

and as the lava was coming up,

it went through sedimentary rocks that have got a lot of carbon in,

and the lava picked the carbon up

and you've got a chemical reaction happening where the iron,

which was bonded with oxygen just like here in the hematite,

actually became metallic iron. It reduced the iron from the lava.

We can see this is also a sample of iron, so this is iron.

This is a sample of lava from Disko Island

so there is some metal in there but not as big as that.

This one is a very grey colour and that's due to the graphite

and carbon in here?

You can see a bit of a smudge on the paper.

There's a black smear there.

That's just from the carbon that's present in here, the graphite?

That's right. Actually, we've got a clip of a blast furnace to show.

This is how iron is now manufactured

and this is using carbon to steal away the oxygen from the iron ore,

from the hematite.

This is how we're producing iron but what you're saying now is that...

Nature beat us to it about 55 million years ago.

Exactly. That is quite amazing.

Thank you very much for bringing these samples on.

Now, I really wanted to produce some molten iron for you

here in the lecture theatre, but clearly we couldn't bring in

a blast furnace, so we had to think of another way to do this.

We can learn from what we did earlier,

when we used the magnesium metal to steal the oxygen away

from the carbon dioxide.

We can do the same thing now with our iron oxide.

We can use a more reactive metal

and we are going to use the metal, aluminium.

You may be wondering why there's a safe under here.

This is because we have a bit of an embarrassing story here.

We accidentally locked Andy's Christmas bonus in the safe.

We tried getting into the safe and it's pretty hard.

It's made of pretty solid stuff. We can't really get into this

but the energy generated as the oxygen is taken away

by the aluminium to form iron should be enough to get in here.

Can we have a little look in here?

Get the camera right in to show what's inside this vessel.

This is made of a very tough form of carbon. This is made of graphite,

and you may be able to see the orangey colour.

That's our iron oxide. It's mixed with aluminium powder.

The thing you see sticking out there is a little bit of magnesium

I'm going to use to start this reaction.

Hopefully, we should generate some iron

and see if we can get through into the safe.

Sounds like a good idea, doesn't it? If it's the only way to do it.

I think we will need a safety screen around this, though.

I'm going to need a glove as well. Thank you very much.

Feeling confident? Yeah, I can't see what could go wrong.

What could possibly go wrong? Exactly.

Let's give it a go. You'll see a bright white light first of all.

That's just the magnesium we saw earlier.

The magnesium combining with the oxygen from the air.

OK. We should know when it starts. I think it's started now!

This is our little blast furnace here. Look at that, fantastic.

We've got some molten metal there. Can we lose the safety screen?

That would be good if we can possibly take this off. Lovely job.

Right off the top very carefully. I'm just going to see...

I'll give you that, see if we can pick up this.

What have we got here? Yes, that's wonderful.

It releases such an enormous amount of energy

as the aluminium combines with the oxygen from the iron oxide.

Good news, Andy. Good news and bad news.

The good news is there's a hole in the top of the safe.

The bad news is there's a lot of smoke coming from outside.

I think I've just found the key as well!

Now he finds the key! At least we got into the safe, well done.

Thank you very much for that.

APPLAUSE

We formed there during that reaction aluminium oxide

as the aluminium took the oxygen away.

This is how we find aluminium in nature.

We find it as aluminium oxide and here's a sample here.

What do you think of that?

It is light and this is because it's a very light metal, aluminium.

How can we get our aluminium out of this rock?

This, for a long time, was a great problem.

It was only solved when chemists realised they could use

an even more reactive metal and this was the metal over here,

the metal potassium.

When this was first discovered, it was a bit of a curiosity.

There was this amazing substance, aluminium,

and it did have very remarkable properties.

I'll need another volunteer from the audience.

We'll have someone this side.

In the green, would you like to come down, please?

APPLAUSE

Your name is? Ailish. Ailish, OK, great.

Obviously you've seen a lot of aluminium before, haven't you?

It's very cheap now because now we have worked out

how to extract it from the ores, but initially,

it was incredibly difficult and that made it incredibly expensive.

In fact, so valuable and so strange that this chap,

this is Napoleon III,

he had a whole cutlery set made from aluminium.

I think we have some aluminium utensils here

so you have a look at these. What do you think?

Very light. They are very light, aren't they?

This was the remarkable thing.

With Napoleon's cutlery set, he had his cutlery,

and it was so valuable that if he had a huge feast,

he would give his most honoured guests the aluminium cutlery

and all the rest had to make do with gold.

OK, it seems strange to us now

because we do know how to extract aluminium

and it is incredibly abundant and we can find loads of it around

but it was very difficult to get it out.

Can I just say, it does feel very light indeed.

That is one of the remarkable properties.

It isn't actually the lightest metal that's known.

Do you know what the lightest metal is? Lithium.

Oh, yes, you're quite right. It is lithium. Give us a wave, lithium!

Lithium is in fact a metal and it is incredibly light.

We have made the world's first lithium spoon,

which is very exciting. Here it is.

This is our special RI spoon.

Isn't that beautiful? Would you like to feel this?

It's really light. It really is. It's amazingly light.

It feels almost like plastic but it is solid metal.

It is quite remarkable, don't you think?

This is my dinner, I think.

Some soup. Of course, cutlery sinks in it,

but would you just drop it in and step back?

Look at that? First of all,

it is incredibly light and it's floating on the surface,

but it's also reacting.

I'm going to fish that out. It's very reactive indeed.

I don't think lithium spoons are going to catch on at all, do you?

This is because it's just too reactive. Too explosive.

Exactly, thank you very much indeed.

APPLAUSE

A bit of coughing there just from the reaction

as the lithium combines with the oxygen.

It's reacting with the water vapour.

COUGHING

Yes, yes. Thank you. The lithium there, it floats on the surface.

It is incredibly light but it's incredibly reactive as well.

That may be the world's first lithium spoon

but I think it's safe to say it's also going to be the world's last.

It does show how reactive lithium is and maybe be can use this element

to prepare new elements, and we can indeed.

We have a reaction here to generate a new element from silicon dioxide.

Does anyone know where we find silicon dioxide?

Any ideas, right at the back?

In sand, you're quite right.

We find silicon dioxide, it is sand.

We've got some lithium in here and some sand.

We've mixed the two together, little lithium pelts and some sand,

and I'm going to heat this up at the moment and see what happens.

This is lithium with silicon dioxide

and the silicon dioxide is a mineral, it's just sand.

Quartz is the same stuff, silicon dioxide,

so sand is smashed up pieces of quartz.

I'm hoping that we should see a reaction take place

and there we are.

This is a very violent reaction again

and this is as the lithium is stealing the oxygen away

from the silicon dioxide that makes up the sand.

Anyone have a guess at what we're going to make? Silicon, very good.

We take the oxygen away from the silicon dioxide

and we end up with silicon.

Remarkably, this is a single crystal

of a very purified silicon.

It's very valuable and very precious

and I need to put on some special gloves for this.

It's hard, it's very solid.

It's sort of like a metal and it's incredibly heavy.

Actually, I can hardly lift this thing up,

but it's grown in this very special way here.

This is one crystal of silicon

but it has a seam running all the way along the top here.

This just proves that it is in fact one crystal.

Why do people grow these?

They grow them from the molten silicon.

They would keep purifying it, heating it

and allowing it to cool into this rather strange-looking shape.

They do this because they're trying to make these,

and this is a silicon wafer.

It's just a sheet of silicon, just a slice from this,

and these are used to make silicon chips.

This is the same slice of silicon

and then they're etching in and adding other reagents to this,

gradually building up the silicon chips that we have

in our mobile phones and in our computers.

A fantastic use for this element, silicon.

The element we extract from sand.

Chemists are always finding new uses for the elements.

Even though this has been known for well over 100 years,

it is only relatively recently that we have found out

how to use this element to make silicon chips.

So far in the lecture,

we swapped elements around to make different useful materials.

We've stolen oxygen from iron oxide to make iron,

and we've stolen it from sand.

We've even rearranged the structures of carbon

to turn graphite into diamond.

What we still haven't done is turn one element into another.

That's what the alchemists were trying to do,

to turn lead into gold. Is this possible?

Can we turn one element into another?

Yes, this is the process of radioactivity,

and this occurs deep in the Earth and indeed all around us.

Can we have our periodic table up, please?

Those of you, you elements who are radioactive,

I'd like you to stand up, please.

All the radioactive elements. That's all of this front row here.

Yes, you're all radioactive.

Bismuth, we're not sure about you, you're unknown,

but actually you're so radioactive,

you're no longer who you thought you were.

You'd better sit down again. What does that mean?

Why do you have to sit down again?

It's because during radioactive decay,

an element changes into another element.

If we have cards down for a moment, please?

Remember, what makes an element unique

is the heart of the atom itself.

That's the number of protons that it has within it.

This represents what's inside an atom.

This is its nucleus, and we have to count the number of the red spheres,

these represent the protons,

to work out what element this is.

In fact, this is the element uranium.

The thing about uranium is - oops - it's unstable,

and bits drop off.

The nucleus here just gets so large

that it's very difficult for all these things to stay together

and, yes, bits do drop off and when they drop off,

it's changed into different element.

It's the number of the red protons that define an element,

so if we lose two,

it's no longer what we thought it was to start off with.

Can we find uranium in our periodic table. Where's uranium?

Would you like to stand up?

Uranium, you are radioactive, and bits do drop off.

Quite slowly, don't worry, we won't notice.

But actually when it does happen, when it does fall off,

you change into a different element

and you move a couple of spaces along.

You become thorium, so maybe you should move over to thorium.

Better put your card down because you're not "U" any more. Get it?

You're no longer you, you're actually thorium.

You'd better go over there, you are on thorium's space now.

Actually, both thorium and uranium have also decayed,

and if you decay now, you're going to become the element radon.

You're also radioactive, I'm afraid, so if you decay,

you lose a couple of protons in an alpha particle.

You're not radon any more, you've become polonium.

Can we see this in action?

We can, using this apparatus here.

This is known as a cloud chamber.

The tank that we see here contains an atmosphere of alcohol vapour

and it's got a lot of vapour in there

and it's actually trying to form little droplets.

There's a temperature gradient.

There's a little heating wire at the top and it's cooled down

from underneath, so it's gradually freezing.

It wants to form droplets but actually it's much easier

if there's something there to help it.

Any charged particles can cause this.

All the tracks that you can see now,

all these little wispy white trails,

are actually particles of radiation.

This is natural radiation just in the air around us.

We don't tend to think of radioactivity as being very natural,

but of course, we're all weakly radioactive

because of some of the radioactive elements in us.

Here, we can see radiation in action here just in the air around us.

I'm going to introduce into this a sample of a radioactive element

called americium.

Look at that. You can see the tracks forming here.

Each little track that we see is the result of a charged particle

being emitted from the element americium

and the particles emitted are alpha particles.

The alpha particle is two protons, two neutrons,

and actually that is the heart of an atom of helium.

What we're actually seeing here is the birth of helium atoms,

which I think is quite remarkable. I'll just put this away.

It is possible then to change one atom into another.

Nature seems to do this, but can we?

Actually, it is possible,

and one of the first people to generate lots of different atoms

was this chap here, Glenn Seaborg.

In fact, he even has an element named after him.

Where's seaborgium? There we are,

right in the middle of the periodic table.

In 1980, Seaborg did an amazing experiment.

He took bismuth and he turned it into gold.

This is what the alchemists had been dreaming of.

He changed one element into gold.

What he did was take bismuth -

can we have our periodic table up for a second, please?

He took the element bismuth and he fired atoms of carbon and neon

at this and it knocked out a number of protons

until we ended up with gold.

Unfortunately, he only ended up with the few thousand atoms

and this is not enough to get him rich.

It was a very expensive experiment, took a lot of money to get this

and all he made was a few atoms, but it is possible to do it.

Radioactivity is a natural process but it can also be brought about

by firing one atom at another,

and changing it and creating new, heavier elements

or even to make gold.

Do we even want to make gold?

Are there other things that fascinated the alchemists

which modern scientists have taken one step further?

This is another naturally occurring rock

that has really quite remarkable properties.

This one amazed the early alchemists.

I'll show you why.

Over here, our audience members have some paper clips.

Have you got some paper clips?

I'd like you to put your paper clips onto here, just onto the rock.

They should stick by themselves.

It's not a surprise to us because we've all seen magnets before,

but just imagine if you were the first person to ever see a magnet.

I have a book here from the 1530s

that describes this magnetic rock, this lodestone.

They really did find it quite remarkable.

This here shows this magnetic rock.

There's a ship sailing past a mountain that's supposedly made

of this lodestone, this magnetic ore.

You can see here, these are the nails from the ship.

They've supposedly been sucked out of the ship, so this is

a sort of warning that there's this incredibly strange magical material

with these amazing properties which would suck the nails

out of your ship and you'd be shipwrecked.

There's a warning for you. OK, thank you.

Nowadays, scientists have learned how to make even stronger magnets

from the elements, and if we just have our periodic table up again,

some of the strongest magnets now made use the element neodymium.

Give us a wave, up there, very good.

The strongest magnets in the world are made with neodymium.

This element was discovered in the 1880s,

but it was over 100 years later that scientists learnt how to use

this element to create these magnets.

Thank you very much, periodic table.

I have a couple of these magnets here

and they really are very strong indeed.

These are little neodymium magnets.

Here we are, just try to pull these apart?

I can't. Are they stuck together?

No, they're not stuck together. Try again.

Give them to your neighbour, see if he can get them?

Can you pull those apart? No.

I promise you they're not stuck together.

I could probably slide them or something if I push. Look at that.

They're very strong magnets indeed.

Even though the element neodymium has been known for over 100 years,

these magnets have only recently been developed.

Now, these really are quite strong

and I think to show just how strong these are, I need another volunteer.

I think we should have one from this side.

Would you like to come down to the front, please?

APPLAUSE

OK, very good. Are you feeling strong? You are, that's good.

Tell us your name, please. Marie. Marie.

We're just going to bring down this rig here.

We're going to suspend you from the ceiling

using this little magnet here. That's the only magnet.

This is a block of iron. It's not magnetic.

I can show that with a paper clip,

just holding the paper clip, it stays on it

but it's not attracted to it.

This is our magnet.

I'm not going to put the paper clip on this, I'd never get it off again.

If you'd like to come over here, please.

I just need to very carefully put this in the middle. Perfect.

Just clip this on as well.

OK, so you're feeling strong?

If you just hold on to here. That's it.

Can you just raise up the winch then, please?

Hold on strong, hold on tightly and we'll just see if we can lift you

off the ground so you need to hold on very tightly.

Might need to move forward a little bit.

Keep holding on and just watch the feet.

There we are, look at that!

You are now suspended from the ceiling. That's fantastic!

APPLAUSE

It really is pretty strong magnets there.

We can actually hang from them.

It's just using the power of these new magnets

but these are incredibly useful and they find uses for instance

in turbines, but are also used in electric cars and so on as well.

These new materials - very, very useful.

We can create even more amazing materials using the elements.

Can we just have our periodic table up for a moment?

We were using magnets there to suspend

and these were the neodymium magnets,

but this, we're going to use some superconductors

and the superconductors are made from the elements yttrium,

just here. Give us a wave, yttrium.

And from barium, so give us a wave, barium. Very good.

And copper. OK, there's copper,

and oxygen at the top there.

Put you four elements together and we get these amazing materials -

high-temperature superconductors.

This is called a Mobius strip. It's a rather strange looking thing.

How many sides has this got? Two. Well, you'd think so.

Actually, if you start here and you keep on going round,

you actually come back underneath.

If you keep going round, you come back where you started from.

It actually has one side, this mathematical shape,

which is very unusual.

I can show you this using our little superconductor.

This Mobius strip is covered with these neodymium magnets,

these very strong magnets. We've got a superconductor here

and this is the superconductor

that's made from the barium, the yttrium, the copper and the oxygen.

This is the ceramic there. This is this disc in the centre.

We are cooling it with liquid nitrogen

in this little holding tray on the top.

It levitates quite nicely.

There we are, it's come back to where it was.

Now it's actually hanging underneath this strip,

but it needs to be cooled down

so we are cooling it with liquid nitrogen.

That's in order to enable these superconductors to work.

They only work at these very low temperatures,

so eventually it's going to warm up and it will fall off the track

so you need to catch it when it does fall.

You're meant to catch it!

Just pass it to me straight away, thank you. That's lovely.

Thank you very much. Thank you for all your help there.

APPLAUSE

Really quite remarkable properties then of this ceramic

made out of the elements barium, yttrium, copper and oxygen.

We've come a long way since the days of the alchemists

when the whole world could be made from air, water, earth and fire.

I hope you've enjoyed our quest to discover

what's really making up the world around us.

If you remember one thing from these lectures,

it's that the work of the chemist is not complete.

New combinations are being discovered all the time

and nobody knows what exciting properties they may have.

I'd like everyone to pick up your cards one last time

and have a look at your card.

Just remember what element you've got, and I want you to go home

and research about your element

and think what uses can we put this element to,

and what new possibilities could there be? Who knows?

You may be able to solve some of the challenges of the future

and maybe even make something more valuable than gold.

Thank you and goodnight.

APPLAUSE

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