Probably there is not a person on earth who does not hear about isotopes. But not everyone knows what it is. Especially frightening is the phrase "radioactive isotopes". These incomprehensible chemical elements are catching up on the horror of humanity, but in fact they are not as terrible as it might seem at first glance.
In order to understand the concept of radioactive elements, it is necessary first to say that isotopes are samples of the same chemical element, but with different masses. What does it mean? The questions disappear, if for a start we remember the structure of the atom. It consists of electrons, protons and neutrons. The number of the first two elementary particles in the nucleus of the atom is always constant, while the neutrons having their own mass can meet in the same substance in different amounts. This circumstance also generates a variety of chemical elements with different physical properties.
Now we can give a scientific definition to the concept under investigation. So, isotopes - a cumulative set of similar in properties chemical elements, but having a different mass and physical properties. According to more modern terminology, they are called a pleiad of nucleotides of a chemical element.
A bit of history
At the beginning of the last century, scientists have discovered that different masses of electron nuclei can be observed in the same chemical compound under different conditions. From a purely theoretical point of view, such elements could be considered new and begin to fill empty cells in the periodic table of D. Mendeleyev. But there are only nine free cells in it, and scientists have discovered dozens of new elements. In addition, mathematical calculations have shown that the compounds found can not be considered previously unknown, because their chemical properties fully corresponded to the characteristics of those already existing.
After lengthy discussions, it was decided to call these elements isotopes and place them in a single cell with those whose nuclei contain the same number of electrons with them. Scientists managed to determine that isotopes are just some variations of chemical elements. However, the reasons for their occurrence and the duration of life have been studied for almost a century. Even at the beginning of the 21st century, it is impossible to assert that humanity knows absolutely everything about isotopes.
Persistent and unstable variations
Each chemical element has several isotopes. Because there are free neutrons in their nuclei, they do not always enter into stable bonds with the rest of the atoms. After some time, free particles leave the core, because of what changes its mass and physical properties. In this way, other isotopes are formed, which ultimately leads to the formation of a substance with an equal number of protons, neutrons, and electrons.
Those substances that decay very rapidly are called radioactive isotopes. They release into space a large number of neutrons, forming a powerful ionizing gamma-radiation, known for its strong penetrating ability, which adversely affects living organisms.
The more stable isotopes are not radioactive, since the amount of free neutrons released by them is not capable of generating radiation and significantly affecting other atoms.
For quite some time scientists have established one important regularity: each chemical element has its own isotopes, persistent or radioactive. Interestingly, many of them were obtained under laboratory conditions, and their presence in the natural form is small and not always fixed by instruments.
Distribution in nature
Under natural conditions, most often there are substances whose isotope mass is directly determined by its ordinal number in the table of D. Mendeleyev. For example, hydrogen, designated by the symbol H, has the serial number 1, and its mass is equal to one. Its isotopes, 2H and 3H, are extremely rare in nature.
Even the human body has some radioactive isotopes. They get inside through food in the form of carbon isotopes, which, in turn, is absorbed by plants from soil or air and becomes a part of organic substances in the process of photosynthesis. Therefore, man, animals, and plants radiate a certain radiation background. Only it is so low that it does not interfere with normal functioning and growth.
Sources that contribute to the formation of isotopes are the inner layers of the earth's core and radiation from outer space.
As you know, the temperature on the planet largely depends on its hot core. But only recently it became clear that the source of this heat is a complex thermonuclear reaction, in which radioactive isotopes participate.
The decay of isotopes
Since isotopes are unstable formations, it can be assumed that, after a time, they always break up into more permanent nuclei of chemical elements. This statement is true, because scientists have not been able to detect in nature a huge number of radioactive isotopes. And most of those that were extracted in laboratories lasted from a couple of minutes to several days, and then again turned into ordinary chemical elements.
But there are also such isotopes in nature that are very resistant to decay. They can exist for billions of years. Formed such elements in those early times when the earth was still being formed, and on its surface there was not even a solid crust.
Radioactive isotopes decay and re-form very quickly. Therefore, in order to facilitate the assessment of the stability of the isotope, scientists decided to consider the category of its half-life.
Not all readers can immediately understand what is meant by this concept. Let us define it. The half-life of the isotope is the time for which the conditional half of the taken substance ceases to exist.
This does not mean that the remainder of the connection will be destroyed in the same amount of time. With regard to this half, another category should be considered - the period of time for which its second part will disappear, that is, a quarter of the original quantity of matter. And this examination goes on and on. It can be assumed that it is simply impossible to calculate the time for the complete decay of the initial amount of a substance, since this process is practically infinite.
However, scientists, knowing the half-life, can determine what amount of substance existed at the beginning. These data are successfully used in related sciences.
In the modern scientific world, the concept of complete decay is practically not used. Concerning each isotope, it is customary to indicate its half-life, which varies from a few seconds to many billions of years. The smaller the half-life, the greater the radiation emanates from the substance and the higher its radioactivity.
Enrichment of minerals
In some branches of science and technology, the use of relatively large quantities of radioactive substances is considered mandatory. But in this case under natural conditions there are very few such connections.
It is known that isotopes are unrestricted variants of chemical elements. The number of them is measured by several percent of the most resistant species. That is why scientists need to carry out artificial enrichment of fossil materials.
During the years of research it was possible to learn that the decay of an isotope is accompanied by a chain reaction. The released neutrons of one substance begin to affect the other. As a result, heavy nuclei decay into lighter ones and new chemical elements are obtained.
This phenomenon was called the chain reaction, as a result of which it is possible to obtain more stable, but less common isotopes, which are subsequently used in the national economy.
Application of Decay Energy
Also scientists have found out that during the decay of a radioactive isotope, a huge amount of free energy is released. Its amount is usually measured by the Curie unit, equal to the dividing time of 1 g radon-222 per 1 second. The higher this figure, the more energy is released.
This was the reason for developing ways to use free energy. Thus, nuclear reactors appeared, in which a radioactive isotope is placed. Most of the energy allocated to it is collected and converted into electricity. On the basis of these reactors, nuclear power plants are created that provide the cheapest electricity. Reduced versions of such reactors are put on self-propelled mechanisms. Given the danger of accidents, most often these machines are submarines. In case of reactor failure, the number of victims on the submarine will be easier to minimize.
Another very terrible option of using half-life energy is atomic bombs. During the Second World War, they were tested on humanity in the Japanese cities of Hiroshima and Nagasaki. The consequences were very sad. Therefore, in the world there is an agreement on the non-use of this dangerous weapon. At the same time, large states with a focus on militarization continue to continue research in this field. In addition, many of them secretly from the world community make atomic bombs, which are thousands of times more dangerous than those used in Japan.
Isotopes in medicine
For peaceful purposes, the decay of radioactive isotopes has been learned to use in medicine. By directing radiation to the affected area of the body, you can suspend the course of the disease or help the patient completely recover.
But more often radioactive isotopes are used for diagnostics. The thing is that their movement and the nature of the cluster are easiest to fix on the radiation that they produce. So, in the human body is introduced a certain non-hazardous amount of radioactive material, and according to the instruments, physicians observe how and where it will fall.
Thus, the diagnosis of the brain, the nature of cancerous tumors, the peculiarities of the glands of internal and external secretion are carried out.
Application in archeology
It is known that in living organisms there is always radioactive carbon-14, the half-decay of which is 5570 years. In addition, scientists know how much this element contains in the body before the time of his death. This means that all the spilled trees emit the same amount of radiation. With time, the intensity of radiation decreases.
This helps archaeologists determine how long the tree died, from which a galley or any other ship was built, and hence the very time of construction. This method of investigation was called the radioactive carbon analysis. Thanks to him, it is easier for scientists to establish a chronology of historical events.