The most amazing stuff. Radioactive metal and its properties

Among all the elements of the periodic system, a significant part belongs to those that most people talk about with fear. How else? After all, they are radioactive, which means a direct threat to human health.

Let's try to figure out exactly which elements are dangerous, and what they are, and also find out what their harmful effect on the human body is.

General concept of a group of radioactive elements

This group includes metals. There are quite a lot of them, they are located in the periodic system immediately after lead and up to the very last cell. The main criterion by which it is customary to attribute one or another element to the radioactive group is its ability to have a certain half-life.

In other words, it is the transformation of the metal nucleus into another, child, which is accompanied by the emission of radiation of a certain type. At the same time, transformations of one element into another take place.

A radioactive metal is one in which at least one isotope is radioactive. Even if there are six varieties in total, and only one of them will be the carrier of this property, the entire element will be considered radioactive.

Types of radiation

The main variants of radiation emitted by metals during decays are:

• alpha particles;
• beta particles or neutrino decay;
• isomeric transition (gamma rays).

There are two options for the existence of such elements. The first is natural, that is, when a radioactive metal occurs in nature and in the simplest way, under the influence of external forces, over time it is transformed into other forms (shows its radioactivity and decays).

The second group is metals artificially created by scientists, capable of rapid decay and powerful release of large amounts of radiation. This is done for use in certain areas of activity. Installations in which nuclear reactions are produced by the transformation of one element into another are called synchrophasotrons.

The difference between the two indicated methods of half-life is obvious: in both cases it is spontaneous, however, only artificially obtained metals give precisely nuclear reactions in the process of destructuring.

Fundamentals of designation of similar atoms

Since most elements have only one or two isotopes that are radioactive, it is customary to indicate a specific type in the designations, and not the entire element as a whole. For example, lead is just a substance. If we take into account that it is a radioactive metal, then it should be called, for example, "lead-207".

The half-lives of the particles under consideration can vary greatly. There are isotopes that exist for only 0.032 seconds. But on a par with them there are those that decay for millions of years in the bowels of the earth.

Radioactive metals: list

A complete list of all the elements belonging to the group under consideration can be quite impressive, because in total about 80 metals belong to it. First of all, these are all those standing in the periodic system after lead, including the group That is, bismuth, polonium, astatine, radon, francium, radium, rutherfordium, and so on in serial numbers.

Above the indicated border there are many representatives, each of which also has isotopes. However, some of them may be just radioactive. Therefore, it is important what varieties the Radioactive metal has, more precisely one of its isotopic varieties, almost every representative of the table has. For example, they have:

• calcium;
• selenium;
• hafnium;
• tungsten;
• osmium;
• bismuth;
• indium;
• potassium;
• rubidium;
• zirconium;
• europium;
• radium and others.

Thus, it is obvious that there are a lot of elements that exhibit the properties of radioactivity - the vast majority. Some of them are safe due to a too long half-life and are found in nature, while others are artificially created by man for various needs in science and technology and are extremely dangerous for the human body.

Characterization of radium

The name of the element was given by its discoverers - the spouses and Mary. It was these people who first discovered that one of the isotopes of this metal - radium-226 - is the most stable form, which has the special properties of radioactivity. This happened in 1898, and a similar phenomenon only became known. The spouses of chemists just took up a detailed study of it.

The etymology of the word takes its roots from the French language, in which it sounds like radium. A total of 14 isotopic modifications of this element are known. But the most stable forms with mass numbers are:

Form 226 has a pronounced radioactivity. By itself, radium is a chemical element at number 88. Atomic mass. How simple matter is capable of existence. It is a silvery-white radioactive metal with a melting point of about 670 0 C.

From a chemical point of view, it exhibits a fairly high degree of activity and is able to react with:

• water;
• organic acids, forming stable complexes;
• oxygen to form an oxide.

Properties and application

Radium is also a chemical element that forms a series of salts. Its nitrides, chlorides, sulfates, nitrates, carbonates, phosphates, chromates are known. Also available with tungsten and beryllium.

The fact that radium-226 can be hazardous to health was not immediately recognized by its discoverer Pierre Curie. However, he managed to verify this when he conducted an experiment: for a day he walked with a test tube with metal tied to the shoulder of his arm. A non-healing ulcer appeared at the site of contact with the skin, which the scientist could not get rid of for more than two months. The spouses did not refuse their experiments on the phenomenon of radioactivity, and therefore both died from a large dose of radiation.

In addition to the negative value, there are a number of areas in which radium-226 finds use and benefits:

1. Ocean water level shift indicator.
2. Used to determine the amount of uranium in the rock.
3. Included in lighting mixtures.
4. In medicine, it is used to form therapeutic radon baths.
5. Used to remove electrical charges.
6. With its help, flaw detection of casting is carried out and seams of parts are welded.

Plutonium and its isotopes

This element was discovered in the forties of the XX century by American scientists. It was first isolated from where it formed from neptunium. The latter is the result of the decay of the uranium nucleus. That is, they are all closely interconnected by common radioactive transformations.

There are several stable isotopes of this metal. However, the most common and practically important variety is plutonium-239. Known chemical reactions of this metal with:

• oxygen
• acids;
• water;
• alkalis;
• halogens.

In terms of its physical properties, plutonium-239 is a brittle metal with a melting point of 640 0 C. The main methods of influencing the body are the gradual formation of oncological diseases, accumulation in bones and causing their destruction, lung diseases.

The area of ​​use is mainly the nuclear industry. It is known that during the decay of one gram of plutonium-239, such an amount of heat is released that is comparable to 4 tons of burned coal. That is why this one finds such wide application in reactions. Nuclear plutonium is a source of energy in nuclear reactors and thermonuclear bombs. It is also used in the manufacture of electric energy accumulators, the service life of which can reach five years.

Uranus is a source of radiation

This element was discovered in 1789 by the German chemist Klaproth. However, people managed to explore its properties and learn how to put them into practice only in the 20th century. The main distinguishing feature is that radioactive uranium is capable of forming nuclei during natural decay:

• lead-206;
• krypton;
• plutonium-239;
• lead-207;
• xenon.

In nature, this metal is light gray in color, has a melting point of over 1100 0 C. It is found in the composition of minerals:

1. Uranium mica.
2. Uraninite.
3. Nasturan.
4. Otenitis.
5. Tuyanmunit.

Three stable natural isotopes and 11 artificially synthesized isotopes are known, with mass numbers from 227 to 240.

In industry, radioactive uranium is widely used, which can quickly decay with the release of energy. So, it is used:

• in geochemistry;
• mining;
• nuclear reactors;
• in the manufacture of nuclear weapons.

The effect on the human body is no different from the previous considered metals - accumulation leads to an increased dose of radiation and the occurrence of cancerous tumors.

Transuranium elements

The most important of the metals following uranium in the periodic table are those that were discovered very recently. Literally in 2004, sources were published confirming the birth of the 115th element of the periodic system.

They became the most radioactive metal of all known today - ununpentium (Uup). Its properties remain unexplored until now, because the half-life is 0.032 seconds! It is simply impossible to consider and reveal the details of the structure and the manifested features under such conditions.

However, its radioactivity is many times greater than the indicators of the second element in terms of this property - plutonium. Nevertheless, it is not ununpentium that is used in practice, but its "slower" comrades in the table - uranium, plutonium, neptunium, polonium and others.

Another element - unbibium - theoretically exists, but scientists from different countries have not been able to prove this in practice since 1974. The last attempt was made in 2005, but was not confirmed by the general council of chemists.

Thorium

It was discovered back in the 19th century by Berzelius and named after the Scandinavian god Thor. It is a weakly radioactive metal. Five of its 11 isotopes have this feature.

The main use in is not based on the ability to emit a huge amount of thermal energy when decaying. The peculiarity is that thorium nuclei are capable of capturing neutrons and turning into uranium-238 and plutonium-239, which already enter directly into nuclear reactions. Therefore, thorium can also be attributed to the group of metals we are considering.

Polonium

Silver-white radioactive metal number 84 in the periodic system. It was discovered by the same ardent researchers of radioactivity and everything connected with it, the spouses Marie and Pierre Curie in 1898. The main feature of this substance is that it freely exists for about 138.5 days. That is, this is the half-life of this metal.

It occurs naturally in uranium and other ores. It is used as a source of energy, and quite powerful. It is a strategic metal, as it is used to make nuclear weapons. The quantity is strictly limited and is under the control of each state.

It is also used for air ionization, elimination of static electricity in the room, in the manufacture of space heaters and other similar items.

Impact on the human body

All radioactive metals have the ability to penetrate human skin and accumulate inside the body. They are very poorly excreted with waste products, they are not excreted with sweat at all.

Over time, they begin to affect the respiratory, circulatory, nervous systems, causing irreversible changes in them. They affect cells, causing them to function incorrectly. As a result, the formation of malignant tumors, oncological diseases occur.

Therefore, each radioactive metal is a great danger to humans, especially if we talk about them in their pure form. You can not touch them with unprotected hands and be in the room with them without special protective devices.

Man has always sought to find materials that leave no chance for their competitors. Since ancient times, scientists have been looking for the hardest materials in the world, the lightest and heaviest. The thirst for discovery led to the discovery of an ideal gas and an ideal black body. We present you the most amazing substances in the world.

1. The blackest substance

The blackest substance in the world is called Vantablack and consists of a collection of carbon nanotubes (see carbon and its allotropic modifications). Simply put, the material consists of countless "hairs", hitting which, the light bounces from one tube to another. In this way, about 99.965% of the light flux is absorbed and only a negligible part is reflected back to the outside.
The discovery of Vantablack opens up broad prospects for the use of this material in astronomy, electronics and optics.

2. The most combustible substance

Chlorine trifluoride is the most flammable substance ever known to mankind. It is the strongest oxidizing agent and reacts with almost all chemical elements. Chlorine trifluoride can burn through concrete and easily ignites glass! The use of chlorine trifluoride is almost impossible due to its phenomenal flammability and the inability to ensure the safety of use.

3. The most poisonous substance

The most powerful poison is botulinum toxin. We know it under the name Botox, that is how it is called in cosmetology, where it has found its main application. Botulinum toxin is a chemical produced by the bacteria Clostridium botulinum. In addition to the fact that botulinum toxin is the most toxic substance, it also has the largest molecular weight among proteins. The phenomenal toxicity of the substance is evidenced by the fact that only 0.00002 mg min / l of botulinum toxin is enough to make the affected area deadly for humans for half a day.

4. The hottest substance

This is the so-called quark-gluon plasma. The substance was created using the collision of gold atoms at almost the speed of light. Quark-gluon plasma has a temperature of 4 trillion degrees Celsius. For comparison, this figure is 250,000 times higher than the temperature of the Sun! Unfortunately, the lifetime of a substance is limited to one trillionth of a trillionth of a second.

5. The most corrosive acid

Antimony fluoride H becomes the champion in this category. Antimony fluoride is 2×10 16 (two hundred quintillion) times more caustic than sulfuric acid. This is a very active substance that can explode when a small amount of water is added. The fumes of this acid are deadly poisonous.

6. The most explosive substance

The most explosive substance is heptanitrocuban. It is very expensive and is used only for scientific research. But a slightly less explosive HMX is successfully used in military affairs and in geology when drilling wells.

7. The most radioactive substance

Polonium-210 is an isotope of polonium that does not exist in nature, but is made by man. It is used to create miniature, but at the same time, very powerful energy sources. It has a very short half-life and is therefore capable of causing severe radiation sickness.

8. The heaviest substance

It is, of course, fullerite. Its hardness is almost 2 times higher than that of natural diamonds. You can read more about fullerite in our article The Hardest Materials in the World.

9. Strongest magnet

The world's strongest magnet is made up of iron and nitrogen. At present, details about this substance are not available to the general public, but it is already known that the new super-magnet is 18% more powerful than the strongest magnets currently in use - neodymium. Neodymium magnets are made from neodymium, iron and boron.

10. The most fluid substance

Superfluid Helium II has almost no viscosity at temperatures close to absolute zero. This property is due to its unique ability to seep and pour out of a vessel made of any solid material. Helium II has the potential to be used as an ideal thermal conductor in which heat does not dissipate.

Radiation, radioactivity and radio emission are concepts that even sound quite dangerous. In this article, you will learn why some substances are radioactive and what that means. Why is everyone so afraid of radiation and how dangerous is it? Where can we find radioactive substances and what threatens us?

The concept of radioactivity

I call radioactivity the “ability” of atoms of some isotopes to split and create radiation by this. The term "radioactivity" did not appear immediately. Initially, such radiation was called Becquerel rays, in honor of the scientist who discovered it in his work with the uranium isotope. Already now we call this process the term "radioactive radiation".

In this rather complicated process, the original atom is transformed into an atom of a completely different chemical element. Due to the ejection of alpha or beta particles, the mass number of the atom changes and, accordingly, this moves it along the table of D. I. Mendeleev. It is worth noting that the mass number changes, but the mass itself remains almost the same.

Based on this information, we can slightly rephrase the definition of the concept. So, radioactivity is also the ability of unstable nuclei of atoms to independently transform into other, more stable and stable nuclei.

Substances - what is it?

Before talking about what radioactive substances are, let's generally define what is called a substance. So, first of all, it is a kind of matter. It is also logical that this matter consists of particles, and in our case these are most often electrons, protons and neutrons. Here we can already talk about atoms, which consist of protons and neutrons. Well, molecules, ions, crystals, and so on are obtained from atoms.

The concept of a chemical substance is based on the same principles. If it is impossible to isolate a nucleus in matter, then it cannot be classified as a chemical substance.

About radioactive substances

As mentioned above, in order to exhibit radioactivity, an atom must spontaneously decay and turn into an atom of a completely different chemical element. If all the atoms of a substance are unstable to such an extent as to decay in this way, then you have a radioactive substance. In a more technical language, the definition would sound like this: substances are radioactive if they contain radionuclides, and in high concentration.

Where are the radioactive substances in the periodic table of D. I. Mendeleev?

A fairly simple and easy way to find out if a substance is radioactive is to look at the table of D. I. Mendeleev. Everything after the element lead is radioactive elements, as well as promethium and technetium. It is important to remember which substances are radioactive, because it can save your life.

There are also a number of elements that have at least one radioactive isotope in their natural mixtures. Here is a partial list of some of the most common elements:

• Potassium.
• Calcium.
• Vanadium.
• Germanium.
• Selenium.
• Rubidium.
• Zirconium.
• Molybdenum.
• Cadmium.
• Indium.

Radioactive substances are those that contain any radioactive isotopes.

Types of radioactive radiation

There are several types of radioactive radiation, which will be discussed now. Alpha and beta radiation have already been mentioned, but this is not the whole list.

Alpha radiation is the weakest radiation, which is dangerous if the particles enter directly into the human body. Such radiation is realized by heavy particles, and that is why it is easily stopped even by a sheet of paper. For the same reason, alpha rays do not travel more than 5 cm.

Beta radiation is stronger than the previous one. This is radiation by electrons, which are much lighter than alpha particles, so they can penetrate a few centimeters into human skin.

Gamma radiation is realized by photons, which quite easily penetrate even further to the internal organs of a person.

The most powerful penetrating radiation is neutron. It is quite difficult to hide from it, but in nature it, in fact, does not exist, except perhaps in close proximity to nuclear reactors.

The impact of radiation on humans

Radioactive substances can often be fatal to humans. In addition, radiation exposure has an irreversible effect. If you have been exposed to radiation, then you are doomed. Depending on the extent of the damage, a person dies within a few hours or over many months.

Along with this, it must be said that people are continuously exposed to radioactive radiation. Thank God it's weak enough to be fatal. For example, watching a football match on TV gives you 1 microrad of radiation. Up to 0.2 rad per year - this is generally the natural radiation background of our planet. 3 gift - your portion of radiation during x-rays of teeth. Well, exposure over 100 rad is already potentially dangerous.

Harmful Radioactive Substances, Examples and Warnings

The most dangerous radioactive substance is Polonium-210. Because of the radiation around it, you can even see a kind of luminous "aura" of blue color. It is worth mentioning that there is a stereotype that all radioactive substances glow. This is not at all the case, although there are options such as Polonium-210. Most radioactive substances are not outwardly suspicious at all.

Livermorium is currently considered the most radioactive metal. Its isotope Livermorium-293 takes 61 milliseconds to decay. This was discovered back in 2000. Ununpentium is slightly inferior to him. The decay time of Ununpentium-289 is 87 milliseconds.

Also an interesting fact is that the same substance can be both harmless (if its isotope is stable) and radioactive (if the nuclei of its isotope are about to collapse).

Scientists who studied radioactivity

Radioactive substances were not considered dangerous for a long time, and therefore they were freely studied. Unfortunately, sad deaths have taught us the need for caution and increased safety with such substances.

One of the first, as already mentioned, was Antoine Becquerel. This is a great French physicist, who owns the glory of the discoverer of radioactivity. For his services, he was awarded membership in the Royal Society of London. Due to his contribution to this area, he died quite young, at the age of 55. But his work is remembered to this day. The unit of radioactivity itself, as well as craters on the Moon and Mars, were named in his honor.

An equally great person was Marie Sklodowska-Curie, who worked with radioactive substances with her husband Pierre Curie. Maria was also French, albeit with Polish roots. In addition to physics, she was engaged in teaching and even active social activities. Marie Curie is the first woman to win the Nobel Prize in two disciplines at once: physics and chemistry. The discovery of such radioactive elements as Radium and Polonium is the merit of Marie and Pierre Curie.

Conclusion

As we can see, radioactivity is a rather complex process that does not always remain under the control of a person. This is one of those cases where people can be absolutely powerless in the face of danger. That is why it is important to remember that really dangerous things can be very deceptive on the outside.

To find out whether a substance is radioactive or not, most often you can already get under its influence. Therefore, be careful and attentive. Radioactive reactions help us in many ways, but we should also not forget that this is a force that is practically beyond our control.

In addition, it is worth remembering the contribution of great scientists to the study of radioactivity. They gave us an incredible amount of useful knowledge that is now saving lives, providing energy to entire countries and helping to cure terrible diseases. Radioactive chemicals are a danger and a blessing to mankind.

Radioactive metals are metals that spontaneously emit a stream of elementary particles into the environment. This process is called alpha(α), beta(β), gamma(γ) radiation or simply radioactive radiation.

All radioactive metals decay over time and turn into stable elements (sometimes going through a whole chain of transformations). For different elements radioactive decay can last from a few milliseconds to several thousand years.

Next to the name of a radioactive element is often indicated by its mass number. isotope. For example, Technetium-91 or 91Tc. Different isotopes of the same element, as a rule, have common physical properties and differ only in the duration of radioactive decay.

List of radioactive metals

Russian name	Name eng.	Most stable isotope	Decay period
Technetium	technetium	Tc-91	4.21 x 10 6 years
Promethium	Promethium	Pm-145	17.4 years
Polonium	Polonium	Po-209	102 years old
Astatine	Astatine	At-210	8.1 hours
France	francium	Fr-223	22 minutes
Radium	Radium	Ra-226	1600 years
Actinium	Actinium	Ac-227	21.77 years old
Thorium	Thorium	Th-229	7.54 x 10 4 years
Protactinium	Protactinium	Pa-231	3.28 x 10 4 years
Uranus	Uranium	U-236	2.34 x 10 7 years
Neptunium	Neptunium	Np-237	2.14 x 10 6 years
Plutonium	plutonium	Pu-244	8.00 x 10 7 years
Americium	americium	Am-243	7370 years
Curium	Curium	Cm-247	1.56 x 10 7 years
Berkelium	Berkelium	Bk-247	1380 years
Californium	california	Cf-251	898 years
Einsteinium	einsteinium	Es-252	471.7 days
Fermi	Fermium	Fm-257	100.5 days
Mendelevium	Mendelevium	Md-258	51.5 days
Nobelium	nobelium	No-259	58 minutes
Laurence	lawrencium	Lr-262	4 hours
resenfordium	Rutherfordium	Rf-265	13 hours
Dubnium	dubnium	Db-268	32 hours
Seaborgium	Seaborgium	Sg-271	2.4 minutes
Bory	Bohrium	Bh-267	17 seconds
Ganiy	Hassium	Hs-269	9.7 seconds
Meitnerius	Meitnerium	Mt-276	0.72 seconds
Darmstadium	Darmstadtium	Ds-281	11.1 seconds
X-ray	Roentgenium	Rg-281	26 seconds
Copernicius	Copernicium	cn-285	29 seconds
Ununtry	Ununtrium	Uut-284	0.48 seconds
Flerovium	Flerovium	Fl-289	2.65 seconds
Ununpentium	Ununpentium	Uup-289	87 milliseconds
Livermorium	Livermorium	Lv-293	61 milliseconds

Radioactive elements are divided into natural(existing in nature) and artificial(obtained as a result of laboratory synthesis). There are not many natural radioactive metals - these are polonium, radium, actinium, thorium, protactinium and uranium. Their most stable isotopes occur naturally, often as ore. All other metals on the list are man-made.

most radioactive metal

The most radioactive metal at the moment - livermorium. Its isotope Livermorium-293 disintegrates in just 61 milliseconds. This isotope was first obtained in Dubna in 2000.

Another highly radioactive metal is ununpentium. Isotope ununpentium-289 has a slightly longer decay period (87 milliseconds).

Of the more or less stable, practically used substances, the most radioactive metal is considered polonium(isotope polonium-210). It is a silvery white radioactive metal. Although its half-life reaches 100 or more days, even one gram of this substance heats up to 500 ° C, and the radiation can instantly kill a person.

What is radiation

Everyone knows that radiation very dangerous and it is better to stay away from radioactive radiation. It is difficult to argue with this, although in reality we are constantly exposed to radiation, wherever we are. There are quite a few in the ground radioactive ore, and from space to Earth constantly arrive charged particles.

In short, radiation is the spontaneous emission of elementary particles. Protons and neutrons are separated from the atoms of a radioactive substance, "flying away" into the external environment. At the same time, the nucleus of the atom gradually changes, turning into another chemical element. When all unstable particles are separated from the nucleus, the atom ceases to be radioactive. For example, thorium-232 at the end of its radioactive decay, it turns into a stable lead.

Science identifies 3 main types of radioactive radiation

alpha radiation(α) is the flow of alpha particles, positively charged. They are relatively large in size and do not pass well even through clothing or paper.

beta radiation(β) is the flux of negatively charged beta particles. They are quite small, easily pass through clothes and penetrate into skin cells, which causes great harm to health. But beta particles do not pass through dense materials such as aluminum.

Gamma radiation(γ) is high frequency electromagnetic radiation. Gamma rays have no charge, but contain a lot of energy. A cluster of gamma particles emits a bright glow. Gamma particles even pass through dense materials, making them very dangerous to living beings. They are stopped only by the densest materials, such as lead.

All these types of radiation are present in one way or another anywhere on the planet. They are not dangerous in small doses, but at high concentrations they can cause very serious damage.

The study of radioactive elements

The discoverer of radioactivity is Wilhelm Roentgen. In 1895, this Prussian physicist first observed radioactive radiation. Based on this discovery, a famous medical device was created, named after the scientist.

In 1896, the study of radioactivity continued Henri Becquerel, he experimented with uranium salts.

In 1898 Pierre Curie in its pure form received the first radioactive metal - radium. Curie, although he discovered the first radioactive element, however, did not have time to properly study it. And the outstanding properties of radium led to the quick death of the scientist, who carelessly carried his "brainchild" in his breast pocket. The great discovery took revenge on its discoverer - Curie died at the age of 47 from a powerful dose of radioactive radiation.

In 1934, an artificial radioactive isotope was synthesized for the first time.

Now many scientists and organizations are engaged in the study of radioactivity.

Extraction and synthesis

Even natural radioactive metals do not occur in nature in their pure form. They are synthesized from uranium ore. The process of obtaining pure metal is extremely laborious. It consists of several stages:

• concentration (crushing and separation of sediment with uranium in water);
• leaching - that is, transferring the uranium precipitate into solution;
• isolation of pure uranium from the resulting solution;
• conversion of uranium to a solid state.

As a result, only a few grams of uranium can be obtained from a ton of uranium ore.

The synthesis of artificial radioactive elements and their isotopes takes place in special laboratories, which create conditions for working with such substances.

Practical use

Most often, radioactive metals are used to generate energy.

Nuclear reactors are devices that use uranium to heat water and create a stream of steam that turns a turbine to generate electricity.

In general, the scope of radioactive elements is quite wide. They are used to study living organisms, diagnose and treat diseases, generate energy, and monitor industrial processes. Radioactive metals are the basis for the creation of nuclear weapons - the most destructive weapons on the planet.

Until the end of the 19th century, all chemical elements seemed to be constant and indivisible. There was no question about how immutable elements could be converted. But the discovery of radioactivity turned the world known to us upside down and paved the way for the discovery of new substances.

Discovery of radioactivity

The honor of discovering the transformation of elements belongs to the French physicist Antoine Becquerel. For one chemical experiment, he needed crystals of uranyl-potassium sulfate. He wrapped the substance in black paper and placed the package next to the photographic plate. After developing the film, the scientist saw the outlines of uranyl crystals in the picture. Despite the thick layer of paper, they were clearly distinguishable. Becquerel repeated this experiment several times, but the result was the same: the outlines of crystals containing uranium were clearly visible on photographic plates.

Becquerel announced the results of the discovery at a regular meeting held by the Paris Academy of Sciences. His report began with the words about "invisible radiation." This is how he described the results of his experiments. After that, the concept of radiation entered the everyday life of physicists.

Curie experiments

The results of Becquerel's observations interested the French scientists Marie and Paul Curie. They rightly considered that not only uranium could have radioactive properties. The researchers noticed that the remains of the ore from which this substance is mined are still highly radioactive. The search for elements that differ from the original ones led to the discovery of a substance with properties similar to uranium. The new radioactive element was named polonium. Marie Curie gave this name to the substance in honor of her homeland - Poland. Following this, radium was discovered. The radioactive element turned out to be a decay product of pure uranium. After that, an era of new, previously not found in nature chemical substances began in chemistry.

Elements

Most of the currently known nuclei of chemical elements are unstable. Over time, such compounds spontaneously decompose into other elements and various tiny particles. The heavier parent element is called the parent material in the physics community. The products formed during the decomposition of a substance are called daughter elements or decay products. The process itself is accompanied by the release of various radioactive particles.

isotopes

The instability of chemical elements can be explained by the existence of different isotopes of the same substance. Isotopes are varieties of some elements of the periodic table with the same properties, but with a different number of neutrons in the nucleus. Very many ordinary chemicals have at least one isotope. The fact that these elements are widely distributed and well studied confirms that they are in a stable state for an arbitrarily long time. But each of these "long-lived" elements contains isotopes. Their nuclei are obtained by scientists in the process of reactions carried out in the laboratory. An artificial radioactive element obtained synthetically cannot exist in a stable state for a long time and decays over time. This process can go in three ways. By the name of elementary particles, which are by-products of a thermonuclear reaction, all three types of decay got their names.

Alpha decay

A radioactive chemical element can be transformed according to the first decay scheme. In this case, an alpha particle is emitted from the nucleus, the energy of which reaches 6 million eV. In a detailed study of the results of the reaction, it was found that this particle is a helium atom. It carries away two protons from the nucleus, so the resulting radioactive element will have an atomic number in the periodic system two positions lower than that of the parent substance.

beta decay

The beta decay reaction is accompanied by the emission of one electron from the nucleus. The appearance of this particle in an atom is associated with the decay of a neuron into an electron, a proton and a neutrino. As the electron leaves the nucleus, the radioactive chemical element increases its atomic number by one and becomes heavier than its parent.

Gamma decay

During gamma decay, the nucleus emits a beam of photons with different energies. These rays are called gamma rays. In this process, the radioactive element is not modified. He just loses his energy.

In itself, the instability that this or that radioactive element possesses does not mean at all that in the presence of a certain number of isotopes, our substance will suddenly disappear, releasing colossal energy in the process. In reality, the disintegration of the nucleus resembles the preparation of popcorn - the chaotic movement of corn grains in a pan, and it is completely unknown which of them will open first. The law of the reaction of radioactive decay can only guarantee that in a certain period of time a number of particles will fly out of the nucleus, proportional to the number of nucleons remaining in the nucleus. In the language of mathematics, this process can be described by the following formula:

Here, there is a proportional dependence of the number of nucleons dN leaving the nucleus during the period dt on the number of all nucleons N present in the nucleus. The coefficient λ is the radioactivity constant of the decaying substance.

The number of nucleons remaining in the nucleus at time t is described by the formula:

N \u003d N 0 e -λt,

where N 0 is the number of nucleons in the nucleus at the beginning of the observation.

For example, the radioactive element halogen with atomic number 85 was discovered only in 1940. Its half-life is quite large - 7.2 hours. The content of radioactive halogen (astatine) on the entire planet does not exceed one gram of pure substance. Thus, in 3.1 hours, the amount of it in nature should, in theory, be halved. But the constant decay processes of uranium and thorium give rise to more and more astatine atoms, albeit in very small doses. Therefore, its quantity in nature remains stable.

Half life

The radioactivity constant is used to determine how quickly the element under study will decay. But for practical problems, physicists often use a quantity called the half-life. This indicator tells how long the substance will lose exactly half of its nucleons. For different isotopes, this period varies from tiny fractions of a second to billions of years.

It is important to understand that time in this equation does not add up, but multiplies. For example, if in a time interval t the substance has lost half of its nucleons, then in a period of 2t it will lose another half of the remaining ones - that is, one fourth of the original number of nucleons.

The emergence of radioactive elements

Naturally, radioactive substances are formed in the upper layers of the Earth's atmosphere, in the ionosphere. Under the action of cosmic radiation, gas at high altitude undergoes various changes that turn a stable substance into a radioactive element. The most common gas in our atmosphere, N 2 , for example, is converted from the stable isotope nitrogen-14 into the radioactive isotope carbon-14.

In our time, much more often a radioactive element occurs in a chain of man-made reactions of atomic fission. This is the name of the processes in which the nucleus of the parent substance decays into two child, and then into four radioactive "granddaughter" nuclei. The classic example is the uranium isotope 238. Its half-life is 4.5 billion years. Almost as long as our planet exists. After ten stages of decay, radioactive uranium turns into stable lead 206. An artificially obtained radioactive element does not differ in its properties from its natural counterpart.

The practical significance of radioactivity

After the Chernobyl disaster, many people started talking seriously about the curtailment of programs for the development of nuclear power plants. But in everyday terms, radioactivity brings great benefits to mankind. The study of the possibilities of its practical application is the science of radiography. For example, radioactive phosphorus is injected into a patient to obtain a complete picture of bone fractures. Nuclear energy also serves to generate heat and electricity. Perhaps in the future we are waiting for new discoveries in this amazing field of science.