Probably not on earth such a person who would not hear about isotopes. But not everyone knows what it is. The phrase “radioactive isotopes” sounds particularly frightening. These incomprehensible chemical elements terrify humanity, but in fact they are not as terrible as it may seem at first glance.
To understand the concept of radioactive elements, it is necessary to begin with to say that isotopes are samples of the same chemical element, but with different mass. What does it mean? Questions will disappear if we start by remembering the structure of the atom. It consists of electrons, protons and neutrons. The number of the first two elementary particles in the nucleus of an atom is always constant, whereas neutrons, having their own mass, can occur in the same substance in different quantities. This circumstance creates a variety of chemical elements with different physical properties.
Now we can give a scientific definition of the concept under study. So, isotopes are a cumulative set of chemical elements with similar properties, but with different mass and physical properties. According to more modern terminology, they are called the pleiad of nucleotides of a chemical element.
A bit of history
At the beginning of the last century, scientists discovered that the same chemical compound under different conditions can exhibit different masses of electron nuclei. From a purely theoretical point of view, such elements could be considered new and begin to fill in empty cells with them in the periodic table of D. Mendeleev. But there are only nine free cells in it, and scientists discovered dozens of new elements. Moreover, mathematical calculations showed that the detected compounds could not be considered previously unknown, because their chemical properties fully corresponded to the characteristics of existing ones.
After lengthy discussions, it was decided to call these elements isotopes and put them in the same cell as those whose nuclei contain the same number of electrons with them. Scientists have succeeded in determining that isotopes are just some variations of chemical elements. However, the causes of their occurrence and longevity have been studied for almost a century. Even at the beginning of the 21st century, it is impossible to assert that mankind knows absolutely everything about isotopes.
Persistent and unstable variations
Each chemical element has several isotopes. Due to the fact that there are free neutrons in their nuclei, they do not always enter into stable bonds with the other components of the atom. After some time, the free particles leave the core, due to which its mass and physical properties change. This way other isotopes are formed, which eventually leads to the formation of a substance with an equal number of protons, neutrons and electrons.
Those substances that decay very quickly are called radioactive isotopes. They release into space a large number of neutrons, forming a powerful ionizing gamma radiation, known for its strong penetrating power, which adversely affects living organisms.
More stable isotopes are not radioactive, since the amount of free neutrons emitted by them is not capable of generating radiation and significantly affect other atoms.
For quite a long time, scientists established one important pattern: each chemical element has its own isotopes, persistent or radioactive. Interestingly, many of them were obtained in the laboratory, and their presence in its natural form is small and not always fixed by instruments.
Spread in nature
Under natural conditions, substances are most often encountered, the mass of the isotope of which is directly determined by its ordinal number in D. Mendeleev’s table. For example, hydrogen, denoted by the symbol H, has the sequence number 1, and its mass is equal to one. Its isotopes, 2H and 3H, are extremely rare in nature.
Even the human body has a certain amount of radioactive isotopes. They get inside through food in the form of carbon isotopes, which, in turn, is absorbed by plants from the soil or air and becomes organic in the process of photosynthesis. Therefore, man, animals, and plants emit a certain radiation background. Only he is so low that it does not interfere with the normal functioning and growth.
Sources that contribute to the formation of isotopes are the inner layers of the earth’s core and radiation from space.
As you know, the temperature on the planet depends largely 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 are involved.
Since isotopes are unstable formations, it can be assumed that they eventually decay into more permanent nuclei of chemical elements. This statement is true because scientists have not been able to detect in the nature of a huge number of radioactive isotopes. Yes, and most of those that were mined in laboratories existed for a couple of minutes to several days, and then again turned into ordinary chemical elements.
But in nature there are such isotopes that are very resistant to decay. They may exist billions of years. Such elements were formed in those days when the earth was still forming, and on its surface there was not even a hard crust.
Radioactive isotopes decay and re-form very quickly. Therefore, in order to facilitate the assessment of the resistance of the isotope, the scientists decided to consider the category of its half-life.
Not all readers can immediately understand what is meant by this concept. We define it. The half-life of an isotope is the time over which the conditional half of the substance taken will cease to exist.
This does not mean that the rest of the connection will be destroyed in the same amount of time. In relation to this half, it is necessary to consider a different category - the period of time in which its second part, that is, a quarter of the initial amount of a substance, disappears. And this consideration continues indefinitely. It can be assumed that the time for complete disintegration of the initial amount of a substance is simply impossible to calculate, since this process is almost endless.
However, scientists, knowing the half-life, can determine how much substance existed at the beginning. This data is successfully used in related sciences.
In the modern scientific world, the concept of total decay is practically not used. With respect to each isotope, it is customary to indicate its half-life, which varies from a few seconds to many billions of years. The lower the half-life, the greater the radiation coming from the substance and the higher its radioactivity.
In some branches of science and technology, the use of a relatively large amount of radioactive substances is considered mandatory. But at the same time in natural conditions there are very few such compounds.
It is known that isotopes are not common variants of chemical elements. Their number is measured by a few percent of the most resistant variety. That is why scientists need to artificially enrich fossil materials.
Over 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 influence another. As a result, heavy nuclei break up into lighter ones and new chemical elements are obtained.
This phenomenon is called the chain reaction, as a result of which it is possible to obtain more persistent, but less common isotopes, which are later used in the national economy.
Application of decay energy
Also, scientists have found that during the decay of a radioactive isotope, a huge amount of free energy is released. Its quantity is usually measured by a Curie unit equal to the fission time of 1 g of radon-222 per 1 second. The higher this indicator, the more energy is released.
This was the reason for developing ways to use free energy. So there were atomic reactors in which the radioactive isotope is placed. Most of the energy released by them is collected and converted into electricity. Based on these reactors, nuclear power plants are being built that provide the cheapest electricity. Reduced versions of such reactors put on self-propelled mechanisms. Given the danger of accidents, most often such machines are submarines. In the event of a reactor failure, the number of victims on a submarine will be easier to minimize.
Another very scary option for using half-life energy is atomic bombs. During World War II, they were tested on humanity in the Japanese cities of Hiroshima and Nagasaki. The consequences were very sad. Therefore, the world has an agreement on the non-use of these dangerous weapons. In a place with the big states with a focus on militarization, and today continue to research in this industry. In addition, many of them secretly make atomic bombs from the world community, 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. Directing radiation to the affected area of the body, you can stop the course of the disease or help the patient to fully recover.
But more often radioactive isotopes are used for diagnostics. The fact is that their movement and the nature of the cluster is easiest to record by the radiation that they produce. Thus, a certain non-hazardous amount of radioactive substance is injected into the human body, and the doctors use the instruments to observe how and where it goes.
Thus, diagnostics of the work of the brain, the nature of cancerous tumors, and 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-life of the isotope of which is 5570 years. In addition, scientists know how much of this element is contained in the body until its death. This means that all the cut trees emit the same amount of radiation. Over time, the radiation intensity decreases.
This helps archaeologists determine how long the tree from which they built the galley or any other ship, and hence the construction time itself, died. This research method is called radioactive carbon analysis. Thanks to him, it is easier for scientists to establish a chronology of historical events.