Uranium, a chemical element: the history of discovery and the reaction of nuclear fission

The article tells about when such a chemical element as uranium was discovered, and in what industries today this substance is used.

Uranium is a chemical element of the energy and military industry

At all times people have tried to find highly efficient sources of energy, and ideally - to create a so-called perpetual motion machine. Unfortunately, the impossibility of its existence was theoretically proved and substantiated in the XIX century, but scientists still never lost hope of realizing the dream of a kind of device that would be able to give out a large amount of "clean" energy for a very long time.

In part, it was possible to realize this with the discovery of a substance such as uranium. A chemical element with this name formed the basis for the development of nuclear reactors, which nowadays provide energy to entire cities, submarines, polar ships and so on. True, their energy can not be called "clean", but in recent years many companies have been developing compact "atomic batteries" based on tritium for wide sale - they have no moving parts and they are safe for health.

However, in this article, we will discuss in detail the history of the discovery of a chemical element called uranium and the fission reaction of its nuclei.

Definition

Uranium is a chemical element that has an atomic number of 92 in the periodic table of Mendeleyev. Its atomic mass is 238,029. It is denoted by the symbol U. Under normal conditions it is a dense, heavy metal of silvery color. If we talk about its radioactivity, then uranium itself is an element with weak radioactivity. Also, it does not have completely stable isotopes. And the most stable of existing isotopes is uranium-338.

With what this element represents, we have figured out, and now we will consider the history of its discovery.

History

Such a substance as natural uranium oxide is known to people since ancient times, and its ancient masters used to make glazes covered with various ceramics for watertightness of vessels and other products, as well as their decoration.

An important date in the history of the discovery of this chemical element was in 1789. It was then that the chemist and German by origin, Martin Klaproth, was able to obtain the first metal-like uranium. And the new element has received the name in honor of an open planet eight years earlier.

Almost 50 years then the uranium obtained was considered to be pure metal, however, in 1840 a chemist from France Eugene Melquior Peligo was able to prove that the material obtained by Klaproth, despite suitable external signs, is not a metal, but uranium oxide. A little later, the same Peligo received a real uranium - a very heavy metal of gray color. It was then that the atomic weight of a substance such as uranium was first determined. The chemical element in 1874 was placed by Dmitry Mendeleev in his famous periodic system of elements, and Mendeleev doubled the atomic weight of the substance in half. And only 12 years later, it was proved by experience that the great chemist was not mistaken in his calculations.

Radioactivity

But a truly broad interest in this element in the scientific community began in 1896, when Becquerel discovered the fact that uranium emits rays that were named after the researcher-the rays of Becquerel. Later, one of the most famous scientists in this field - Maria Curie, called this phenomenon radioactivity.

The next important date in the study of uranium is considered to be the year 1899: it was then that Rutherford discovered that the radiation of uranium is inhomogeneous and is divided into two types - alpha and beta rays. A year later, Paul Villar (Viillard) discovered the third, the last type of radioactive radiation known to us to date, the so-called gamma rays.

Seven years later, in 1906, Rutherford, on the basis of his theory of radioactivity, conducted the first experiments, the purpose of which was to determine the age of various minerals. These studies have begun, including the formation of the theory and practice of radiocarbon analysis.

Fission of uranium nuclei

But perhaps the most important discovery, thanks to which the wide extraction and enrichment of uranium began for both peaceful and military purposes, is the process of fission of uranium nuclei . This happened in 1938, the discovery was carried out by the forces of German physicists Otto Ghana and Fritz Strassmann. Later this theory received scientific confirmation in the works of several German physicists.

The essence of the mechanism discovered by them was as follows: if one irradiates the nucleus of the uranium-235 isotope with a neutron, then, by capturing a free neutron, it begins to divide. And, as we all now know, this process is accompanied by the allocation of a colossal amount of energy. This is mainly due to the kinetic energy of the radiation itself and the fragments of the nucleus. So now we know how the fission of uranium nuclei takes place.

The discovery of this mechanism and its results is the starting point for the use of uranium for both peaceful and military purposes.

If we talk about its use for military purposes, then for the first time the theory that it is possible to create conditions for such a process as a continuous reaction of fission of the uranium nucleus (since enormous energy is needed to undermine a nuclear bomb), Soviet physicists Zeldovich and Khariton proved. But in order to create such a reaction, uranium must be enriched, since in its usual state it does not possess the necessary properties.

We have read the history of this element, now we will understand where it is applied.

Application and types of uranium isotopes

After the discovery of such a process as the reaction of the chain division of uranium, the question was raised before physicists, where can it be used?

At present, there are two main directions, where uranium isotopes are used. This is a peaceful (or energy) industry and a military one. Both the first and second use the fission reaction of the isotope nuclei of uranium-235, only the output power is different. Simply put, in an atomic reactor, there is no need to create and maintain this process with the same capacity as is necessary for an explosion of a nuclear bomb.

So, the main branches in which the fission reaction of uranium is used were listed.

But obtaining the uranium-235 isotope is an extraordinarily complex and costly technological task, and not every state can afford to build concentrators. For example, to produce 20 tons of uranium fuel, in which the uranium isotope 235 content will be from 3-5%, it will be necessary to enrich more than 153 tons of natural, "raw" uranium.

The uranium-238 isotope is mainly used in the constructive scheme of nuclear weapons to increase its power. Also, when he captures a neutron with the subsequent beta-decay process, this isotope can eventually be converted into plutonium-239, a common fuel for most modern nuclear reactors.

Despite all the shortcomings of such reactors (high cost, complexity of service, danger of failure), their operation pays off very quickly, and they produce incomparably more energy than classical thermal or hydroelectric power stations.

Also, the reaction of fission of the uranium core allowed the creation of nuclear weapons of mass destruction. It differs tremendous power, relative compactness and that it is capable of making large areas of land unsuitable for living. True, modern nuclear weapons use plutonium, not uranium.

Depleted uranium

There is also a kind of uranium, as depleted. It has a very low level of radioactivity, which means it is not dangerous for people. It is used again in the military sphere, for example, it is added to the armor of the American tank Abrams to give it an additional fortress. In addition, in almost all high-tech armies, you can find various shells with depleted uranium. In addition to the high mass, they have another very interesting property: after the destruction of the projectile, its fragments and metallic dust self-ignite. And by the way, for the first time such a shell was used during the Second World War. As we see, uranium is an element that has been used in various fields of human activity.

Conclusion

According to the scientists' forecasts, in about 2030 all large uranium deposits will be completely depleted, after which the development of hard-to-reach layers of it will start and the price will increase. By the way, uranium ore itself is absolutely harmless for people - some miners work on its extraction by whole generations. Now we have understood the history of the discovery of this chemical element and how the fission reaction of its nuclei is applied.

By the way, an interesting fact is known - uranium compounds were used for a long time as paints for porcelain and glass (so-called uranium glass) until the 1950s.