You can see here President Diem near Damien on Dhe pra medium is round the back pra medium is element 61 between near Damien Elements 60 and Samaria MME Elements 62.

Now people realize that there must be an element between those two before permitting was discovered on the way that they argue this The way that they thought that there must be an element was by looking at atomic weights, relative atomic masses.

So this is a book from 1922 which I bought as the second hand book when I was a schoolboy.

Has a table of atomic numbers on atomic weights, and down here you can see the table of the atomic weights.

Now it's called relative atomic mass.

Between most of these elements, the difference in weight is somewhere between two and three units.

Occasionally it's a bit more, but most of the time it's two or three.

And when you come to near Dimi, um, and some Mariam, the difference is six.

So the gap just seemed too big, So people thought they must be an element there they went through many claims.

We have found elements 61 which turned out to be wrong and the reason why none of them found it with.

Because elements 61 pra medium is radioactive, its longest lived isotope has a lifetime of 3.7 years.

The most common one is even sort.

You mentioned that they deduced there must be one between neodymium and Samaria because of the gap in the in the waist.

Yet in the masses couldn't have done the same by looking at the the violence of Neodymium and Samaria What those things reacted with and figured out.

Hang on.

This one must have 60 electrons and this one must have 62.

Therefore there must be won with 61.

I think that when people started doing this, they didn't really know about electrons.

As far as I know, Mendeleev didn't believe in electrons on dhe.

The other thing is that these elements not so much premie theme, but the other ones can have variable Vaillant so they can make different numbers of it chlorides or oxide or oxides.

But it is true that one chemist deduced by looking at the reaction of hydrogen that near Damien reacted with two atoms of hydrogen.

Samari, um, reacted with none so that he thought there should be an element that would react with one atom of hydrogen.

So you see, Brady, you're really clever.

It was only when the Manhattan Project, the nuclear weapons project, started in the United States when there was a large amount of radioactive research being done, that enough radioactive isotopes were formed, that people had a chance off detecting it.

And in fact, the paper announcing the discovery of pra medium not by its name.

But his element 61 was published just a few weeks, probably only four weeks before I was born.

So I feel a certain residence with this element.

We were born and MME.

Or less the same time.

Still a very long time ago.

Aunt.

Yes.

So I've got the paper here on Dhe.

What's interesting about this paper is that it is extremely modest compared to modern papers describing discovery of a new element where their press conferences, big ceremonies.

You can see our video about some of these ceremonies here at the end of a paragraph.

It just says in this paper, is reported the successful separation of these three elements.

The first have been achieved with radio isotopes of near Damien.

And these are the four words that describe the new discovery on Development 61.

You can't get much lower key than that.

The paper is by three authors, Marin Ski Clendenin and Korea LL, who were working at the Clinton Laboratories at Oak Ridge, Tennessee.

This is a laboratory that has been involved with the birth of many elements.

Most recently, they participated in the synthesis of Element 117 Tennessean, which is named after Tennessee.

Now, the way that these three authors separated pra medium was by of what was then a very new technique called ion exchange chromatography, in which they had the column of essentially plastic beads that had acid groups on it.

On dhe, the element forms positive irons, which can interact with the acid to form assault on dhe.

If you have liquid flowing through the column in this case, it was a solution of assault.

Then, if you put in a mixture of metal lines at the top, they are.

The different elements are attracted with different strengths to the beads of this solid acid, and they come out different times at the bottom.

It turns out that the heaviest element comes up first on dhe.

They have graphs which so, how these different elements come out here.

This is the key graph where they so the number of liters going along here and the amount of radio activity that they measure on dhe there are different peaks on this is the peak for element 61.

Once they have isolated some solution with this element in it, they could distinguish it safe from near Dimi.

Um, because the radioactive decay has a different half life.

The energy of the electrons coming out is different and so on.

So they knew they had something different.

I really like reading this paper.

I read this one on the tram when I was going home.

I got really excited by the time the time got to the final stuff.

This element has had a number of different names when people have thought they discovered it and hadn't because in the old days there wasn't a committee that looked at the evidence before an element was named.

So it was called or people thought they would call it Illini, Um, presumably after Illinois.

Florent iam after Florence in Italy.

Cyclone ium, I don't know what about and finally Prometheus.

Prometheus comes from the Greek legendary figure Prometheus who stole fire from the gods.

The naming was a reference to the discovery of nuclear weapons on DDE in a way sort of stealing the power from the gods.

The opera medium is formed as a product from the nuclear fission of other elements.

And I think it's important to realize that when say, a uranium atom splits, not all the uranium atoms split the same way.

So there are a number of different pathways on one of them.

Fairly minor pathway leads to pra medium.

So once people started carrying out nuclear activities on the large scale nuclear reactors, then in the reaction products, the fission products, they accumulated significant quantities of prom medium so that you could start thinking about the uses on dhe.

There is one use which I think is fascinating of pra medium, which is fairly so lived.

It was a good technology, but it didn't last very long.

Was making batteries so called nuclear batteries, their number of applications where you want a battery to last as long as possible.

For example, heart pacemakers when you have an electrical unit embedded inside somebody's chest.

Thankfully, I don't have one, and you want the battery in that case, to last a long as possible.

Conventional batteries, even the ones in our phones really don't last very long.

As you probably know, you charge it up every day.

But the idea was to make so called nuclear batteries on dhe.

The idea of the pre meeting battery was that for a medium decays by beater decay that is emitting an electron, which in itself is promising for making a battery because the electrons don't go very far.

So it's easy to stop the electrons coming out off the battery.

So the idea is that you mix the prom idiom with a material which, if the atoms are hit by an electron, they give out light.

So called phosphor forceful CZ used to be used on old fashioned television screens where you had a coating which was bombarded by electrons and light came out so you could see the picture.

So the idea is that you have the mixture of pra medium and the forceful which glows.

Light comes out and you sandwich this between two photo sales on the photo sales.

Take the light and produce a voltage, and it has one enormous advantage over conventional batteries.

The conventional battery like this one, or the ones who have in your cars a very temperature dependent.

If the weather is very cold, it's difficult to start your car because the battery has lower voltage, the Promethean battery with much less temperature dependent so it could be cool to very low temperatures on dhe, potentially say on the spacecraft on dhe would still produce a very similar voltage because it was not relying on the chemical reaction, but on this photo electric effect.

The problem and the reason why the technology has no largely been superseded is that the half life of the promethean is very short.

So the amount of promethean in your battery decayed by half every two point something years.

So if you were trying to travel to a distant star, the battery would have gone flat long before you got there.

If you want one set of facts to impress your friends, you can tell them that permit him hydroxide is brown.

Permit him.

Chloride is yellow and primitive.