Name: フランシウム - 動画の周期表 (Francium - Periodic Table of Videos)
Uploaded: 2021-01-14T10:15:15.000Z
Duration: 12 min 59 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Francium is the heaviest of the alkali metals.

基礎受動態

At least until element 119 is synthesized.

It also has the biggest atom of any element

in the whole periodic table. Now some of you may have seen on YouTube,

there are videos that pretend to be huge explosions of francium

And I'm never quite sure whether I should be really pleased about this,

because it shows that people are using the periodic table in the right way,

and deducing that francium should be really very reactive

Or whether I should be tearing out my hair.

Because the videos are fake, and they are chemically wrong

But most of all they miss the really exciting part about francium.

Which is the really moving story about Marguerite Perey

the woman who discovered francium at the beginning of the 20th century

it was obvious that they ought to be an element at the bottom of the

Alkali metals and so lots of people were looking for it the American professor Fred Allison

in Alabama, the one who thought he'd discovered element 85,

Method that he was using which is quite complicated, so I won't explain it now was fundamentally flawed

It was wrong, and he wasn't measuring anything

Except something psychological in his mind. It was realized fairly early on

That element 87 could be made from element 89 actinium

by emission of an alpha particle an alpha particle is two protons and two neutrons,

so if you take two away from 89 you get 87

is quite a rare element and was very difficult to get hold of a sample it had been discovered by Andre Debierne

Around about 1900 he was working in the same Institute as Marie Curie

Started as a lab assistant with Marie Curie, and she was put to purifying

actinium. You would begin with literally tons of impure ore.

Probably of uranium, and then you would gradually

Extract material until you ended up with just a few milligrams of the material you wanted.

The other problem was that nobody realized how dangerous radioactivity was.

So they were all working in the lab with very few precautions the upshot of this was that

Margaret Perey became a real expert in handling actinium

and separating it four years after she started Madame Curie died. She started working simultaneously

for Andre Debierne, the professor who had discovered

Irène Curie Joliot you for some completely unknown reason these two people didn't realize they were both

directing the work of the same person the aim was to get the purest possible sample of actinium

and then measured the radioactivity coming from it the way the actinium decays

is entirely due to the physics of the nucleus the reason for purifying it is to get rid of all the other radioactive

Impurities which might send out signals that would completely mask the effect you were looking for so what

solution of actinium and measured the radioactivity very rapidly for the first two hours the

radioactivity of the solution increased and then it came approximately constant, and so she deduced that what was happening

Actinium was decaying to form a new element

which itself was decaying and giving out much stronger radiation the reason you saw this buildup was because

And you got to a stage where it was being formed at the same rate as at which it was decaying

She also discovered that this radioactivity could be precipitated by

adding caesium salt and then precipitating the caesium salt as a

Element 87 should have similar chemical properties

So you expect them to precipitate together whence it precipitated you could show that the precipitate was radioactive

Rather than the solution and the half-life was about 21 minutes

The upshot was that she had discovered element 87

In 1939 she published her paper on element 87 derived from Actinium

Now there was a really exciting and interesting situation

Marguerite was a lab assistant. She had no chemical qualifications

But she had enough material for a doctorate

But she couldn't submit this material for a doctorate

Because she didn't have a chemistry degree what happened was that she was allowed to go and study

During the Second World War to get the necessary

her main discovery for doctoral thesis now the interesting thing about this paper

And there's the name here of Jean Pepin the person who actually submitted this paper to the journal on her behalf

What's interesting that neither of the two professors have their names on the papers and

apparently after the discovery had been made

Marguerite was as it were double-timing them and working with both of them and neither of them could agree

And eventually they decided that she should publish just alone it was probably a misunderstanding

and perhaps a reflection of the way that lab assistants were treated

And nobody actually asked her who she was working for they were both ordering her about now in

she was asked what name she wanted for the element

And she suggested that she should call it catium,

because she believed that being at the bottom of the periodic table

it would form cation a positive ion more easily than any other element

who spoke English, said she thought it was a bad name because English speakers would think it was something to do with cats,

the furry animals, therefore it wasn't appropriate for name for an element so instead the second choice was

In fact Seaborg wrote to Margaery purée to ask which was the correct symbol

impressive career. She was made a professor of chemistry

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フランシウム - 動画の周期表 (Francium - Periodic Table of Videos)

chronic

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realize

expect