1900: A physics genius wandering around Europe

Chapter 684 The Transuranium Controversy! Lanthanum-Acetene Diodes! Each Using Their Own Methods! Finding Alternative Paths! Marie Curie's Biji
France, Radium Institute.

The Elena couple are conducting research on transuranium.

This experiment is a typical example of a combination of physics and chemistry.

Bombarding uranium with neutrons is a physical process, but separating the products of a nuclear reaction is a chemical process.

Thanks to the birth of quantum mechanics, chemistry has made rapid progress.

The most important breakthrough was that chemists gained a deeper understanding of the elements on the periodic table.

That is, by studying the arrangement of electrons outside the nucleus, the properties of an element can be predicted theoretically.

This was unimaginable before.

For example, chlorine gas is toxic and extremely reactive because chlorine atoms have a very strong oxidizing ability.

Oxidizing power refers to the ease with which an electron can be captured.

The easier it is for an element to lose electrons from the outside, the stronger its oxidizing power.

But why does chlorine have oxidizing power, and why is its oxidizing power stronger than that of oxygen?
With the theory of electron configuration outside the nucleus, this can be explained.

A chlorine atom has 7 electrons in its outermost shell, while an oxygen atom has 6 electrons in its outermost shell.

Atoms tend to maintain a stable state of electrons outside the nucleus, and eight electrons constitute a stable state.

Therefore, chlorine atoms have a stronger ability to steal electrons than oxygen atoms.

Therefore, chlorine atoms have a stronger oxidizing power.

Based on this theory, chemists have conducted a systematic analysis of all the elements in the periodic table.

They discovered a strange phenomenon.

In the periodic table, from element 57 (lanthanum) to element 71 (lutetium), these 15 elements have slight differences in their electron configurations, but their chemical properties are extremely similar.

Therefore, chemists grouped these elements into a separate series, occupying the same position in the periodic table.

This is the famous lanthanide group.

Including: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

At first glance, it seems quite unfamiliar.

But they also have another name that everyone is familiar with: rare earth elements.

The lanthanides are all members of the rare earth elements, and they play a very important role in high-tech fields, especially in defense, electronics, and new energy.

The state strictly regulates the trade of rare earth elements.

Rare earth elements are precious because, on the one hand, these elements are extremely dispersed in the Earth's crust and are present in very small amounts.

On the other hand, the separation and purification process is extremely difficult.

Because their chemical properties are very similar, they are difficult to separate using conventional methods.

In addition to the lanthanides, chemists have discovered another similar group of elements, namely the actinides.

Currently, there are only four actinide elements: actinium, thorium, protactinium, and uranium.

In later generations, the complete set of actinide elements also consisted of 15 elements, from element 89 [actinium] to element 103 [ruthenium].

Including: actinium, thorium, protactinium, uranium, neptunium, plutonium, americium, curium, berberine, californium, einium, fermium, mendelianium, nobe, and ruthenium.

As mentioned earlier, the first six elements of the actinides are naturally occurring in the universe, while the latter are artificially synthesized.

When Fermi discovered transuranic elements, chemists drew parallels with the lanthanides and naturally concluded that transuranic elements 93 and 94 must also belong to the actinides.

Therefore, the chemical properties of transuranium should be similar to those of actinium, thorium, protactinium, and uranium.

This makes separation extremely difficult, and even top chemists cannot guarantee it.

Perhaps all the hard work over a year or two will be in vain.

Therefore, everyone understands that Fermi published his paper without actually purifying transuranium.

More than half a year has passed since transuranium was first proposed, and researchers have put forward several feasible separation methods.

The first method is "extraction".

This method utilizes the difference in solubility of elements in two immiscible solvents to achieve separation.

For example, assuming the reaction products are sugar and fat, they can be placed in a mixed solution of oil and water and then left to stand until the water and oil separate into layers.

At this point, the sugar dissolves in the water, while the fat dissolves in the oil, thus separating the two products.

Then, other methods are used to remove the sugar from the water and the fat from the oil.

The second method is the "precipitation method".

As the name suggests, it is about finding a way to separate transuranic elements dissolved in a solvent into precipitates.

For example, if sodium carbonate is added to a calcium chloride solution, the calcium element will precipitate out as calcium carbonate, which can then be separated.

The third method is "ion exchange method", also known as "adsorption method".

Some special substances, such as resins, have a strong adsorption capacity for heavy metal ions.

This adsorption property comes from the special molecular structure of the resin, which requires a specific metal ion to maintain stability.

Therefore, the resin adsorbs heavy metal ions and exchanges the atoms it carries.

Of course, besides the three methods mentioned above, there are some other strange and unusual methods. The characteristic of chemistry is its complexity and change.

There is no single best one.

However, regardless of the method used, the challenge of similar properties among actinide elements remains.

For example, in the extraction method, transuranic elements and uranium elements may dissolve in the same solvent, such as water, in which case the extraction method will fail.

But similarity is not the same as identicality; there are always some differences.

Perhaps transuranic elements can dissolve in oil in very small amounts.

Therefore, this method requires painstaking effort and puts a great deal of patience on the experimenter.

More importantly, the products of neutron bombardment of uranium include not only uranium and transuranic elements, but also potentially nuclear fission elements ranging from element 82 (lead) to element 91 (protactinium).

In short, isolating transuranic elements is extremely complex and difficult.

At this moment, what Elena and Jolio need to do is find a way to separate the transuranium element from the product, even if it's just a tiny bit.

Unfortunately, they failed once again.

Jolio scratched his head and smiled wryly:
"No wonder Professor Fermi was so troubled; separating transuranic elements is indeed too difficult."

"So much time has passed, and no one has published a paper on it."

Elena did not reply; since returning from Borneo, she had become more mature and composed.

She suddenly said:
"Is it possible to measure the product directly without chemical separation?"

ha?
Jolio was startled.

"How do I measure it?"

Elena replied:
"Acetide elements are all naturally radioactive, therefore transuranic elements should also be radioactive."

"If we can measure a half-life that is different from that of existing elements, wouldn't that indicate that it is a new element?"

Wow!
Upon hearing this, Jolio suddenly understood!
"This is a good idea!"

"Measuring half-life is much simpler than chemical separation."

The couple acted immediately.

They quickly came to a conclusion.

However, the result was somewhat strange.

Jolio looked at the data in his hand and murmured:
A new element with a half-life of 3.5 hours

"This looks a bit like an isotope of element 90, thorium."

"Could the product be thorium instead of transuranic elements?"

Currently, everyone is using neutron bombardment streams generated by natural radioactive sources.

Therefore, the neutron quantity, velocity, and other properties of each research team are different.

Even two experiments conducted by the same team may differ, because the impact process itself is uncontrollable.

This results in each experiment being entirely new and having little reference value.

Jolio was horrified by his own guess.

As a member of the Radium Institute, he had a thorough understanding of the properties of various radioactive elements.

The half-life of each element is different.

Therefore, if the same half-life appears, it is highly likely that it is the same element.

According to Bohr's droplet model, neutrons should have difficulty breaking open uranium nuclei to produce thorium. However, the half-life data shows that they have indeed detected thorium.

This means that the neutron bombarded the uranium nucleus, ejecting two protons, so uranium number 92 became thorium number 90.

Elena was overjoyed.

She believed in Bohr's model, but she also believed in her own results.

The fact that the two conflict means that one of them must be wrong.

As for transuranium, Elena still believes in its existence.

It's just that this experiment didn't produce any results.

So she said:

"Let's compile the results into a paper and publish it first."

"As for the theory, let Bohr and his colleagues have that headache."

Jolio smiled knowingly.

They are experimental physicists, responsible only for discovering new phenomena; how to explain them is left to theoretical physicists.

As a result, their paper was quickly published in a nuclear physics journal.

The article immediately attracted the attention of leading figures in the field of nuclear physics.

Denmark.

When Bohr saw the paper, his first reaction was disbelief.

His droplet model was derived through rigorous theoretical derivation.

However, he also trusted Elena, whose experimental abilities were beyond question.

"Is there something about my model that needs improvement?"

Italy.

After reading the paper, Fermi frowned slightly.

Since the conclusion of the Fifth Bruce Conference and his return to Italy from Borneo, he had been in a state of tension.

Because he has received so many honors in the country.

The entire nation regarded him as a hero.

Fermi couldn't imagine how embarrassing it would be if his transuranium element turned out to be a blunder.

He probably has no choice but to go and dive into the Mariana Trench.

Moreover, after he returned to China, many prominent chemists publicly opposed transuranium.

Almost all of them questioned the sufficiency of his evidence.

However, the opposition also failed to produce sufficient evidence to refute their claims.

Experiments involving neutron bombardment of uranium vary each time, and Irene's results cannot rule out the possibility of transuranium.

Fermi was, after all, good at theory.

He thought:

"What if the droplet model is wrong?"

"So it is indeed possible for a neutron to collide and create fragments."

"All I can say is that anything is possible."

Germany.

Hahn was astonished when he saw Elena and her husband's paper.

This is quite different from Fermi's results on transuranium.

Hahn remarked:
"I never expected that Elena would use physical methods to test the product."

In this life, as Li Qiwei's top student, Hahn dared not slander or look down on Elena in private.

If word gets out, he'll probably have nowhere to go in academia.

Meitner didn't react much to this.

"This result proves nothing."

"Perhaps transuranic elements have the same half-life as thorium."

"Hahn, we need to speed things up."

"We still have a lot of advantages compared to the Curies."

Hahn nodded.

Separating elements is a field of chemistry, and the chemical institute where he works is one of the top in Germany.

Therefore, he was very confident.

Elena's published paper has made the already hot topic of transuranium even more heated.

Some people hope it's true, some hope it's false, and others just want to watch the show.

Elena herself was not satisfied with her discovery.

She knew she had only taken a shortcut; to truly study transuranic elements, she still needed to separate them.

That afternoon, during her rest, Irene lay in a chair and read her mother Marie Curie's notes.

Suddenly, she saw the process by which her mother discovered radium, and a flash of inspiration struck her.

Elena said in surprise:

"My God!"

"How could I forget this!"

Jolio, who was standing nearby, quickly asked:

"what happened?"

Elena asked with a smile:

Do you know how my mother purified radium?

As an expert on Marie Curie, Joliot is extremely knowledgeable about all aspects of Marie Curie's life.

"Of course!"

"Radium exists in the form of sulfate."

"The lady initially mixed radium sulfate solution with solid barium sulfate and adjusted the pH value of the solution to cause radium and barium to co-precipitate."

"Coprecipitation refers to the simultaneous precipitation of two elements under specific conditions."

"Then the radium barium precipitate is dissolved in sodium hydroxide solution, and radium is further separated using ion exchange."

"Finally, high-purity radium is obtained through electrolysis."

"The whole process is extremely complicated, and the solubility of radium is limited, so only a small amount can be purified each time."

This is why radium was so precious back then.

Marie Curie spent countless days and nights working tirelessly through this tedious experimental process to finally purify just a few grams of ore from thousands of tons of ore.

Finally, she donated it all without reservation.

Elena listened with rapt attention.

It's interesting that she, despite being Marie Curie's daughter, always enjoyed listening to others tell stories about her mother.

As soon as Jolio finished speaking, he suddenly thought of something.

"Oh I see!"

"You mean you're considering using the coprecipitation method?"

Irena said:
"That's right!"

"Barium and radium can form a coprecipitate because they are in the same column of the periodic table, with barium directly above radium."

"And since the lanthanides are directly above the actinides, perhaps lanthanides and actinides can also form co-precipitates."

Wow!
Jolio suddenly understood.

"What a brilliant idea!"

Coprecipitation is also a type of precipitation method, but it is obviously more sophisticated, at least you don't have to rack your brains to choose a precipitant.

If transuranic elements are indeed present, they may be co-precipitated by lanthanum, making analysis easier at that point.

This time, their discovery will cause a huge storm in the field of transuranium research!
(End of this chapter)