Among all the elements of the periodic table, 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 he alth.
Let's try to figure out exactly what 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 classify an element as a radioactive one is its ability to have a certain half-life.
In other words, radioactive decay is the transformation of a metal nucleus into another, child, which is accompanied by the emission of radiation of a certain type. At the same time, some elements are transformed into others.
A radioactive metal is one in which at least one isotope is radioactive. Even if all varietiesthere will be six, and at the same time only one of them will be the carrier of this property, the entire element will be considered radioactive.
Types of radiation
The main types of radiation emitted by metals during decay are:
- alpha particles;
- beta particles or neutrino decay;
- isomer 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 exactly nuclear reactions in the process of destructuring.
Basic 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, thenshould be called, for example, "lead-207".
The half-lives of the particles in question can vary greatly. There are isotopes that only exist for 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 elements belonging to the group under consideration can be quite impressive, because in total it includes about 80 metals. First of all, these are all those standing in the periodic system after lead, including the group of lanthanides and actinides. 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 a chemical element has. A radioactive metal, or rather one of its isotopic varieties, is found in almost every representative of the table. For example, they have:
- 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 created artificially by man.for various needs in science and technology and is extremely dangerous for the human body.
Characterization of radium
The name of the element was given by its discoverers - the Curie spouses, Pierre and Maria. 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:
The form 226 has a pronounced radioactivity. Radium itself is a chemical element with number 88. Atomic mass . How simple matter is capable of existence. It is a silvery-white radioactive metal with a melting point of about 6700C.
From a chemical point of view, it exhibits a fairly high degree of activity and is able to react with:
- organic acids, forming stable complexes;
- oxygen forming oxide.
Properties and Applications
Also, radium is a chemical element that forms a series of s alts. Its nitrides, chlorides, sulfates, nitrates, carbonates, phosphates, chromates are known. There are also double s alts with tungsten andberyllium.
The fact that radium-226 can be hazardous to he alth, its discoverer Pierre Curie did not immediately recognize. 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 being negative, there are a number of areas in which radium-226 finds use and benefits:
- Ocean water level shift indicator.
- Used to determine the amount of uranium in the rock.
- Included in lighting blends.
- Used in medicine to form therapeutic radon baths.
- Used to remove electrical charges.
- With its help, flaw detection of castings 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 uranium ore, in which it formed from neptunium. The latter is the result of the decay of the uranium nucleus. That is, all of them are 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 thismetal c:
In terms of its physical properties, plutonium-239 is a brittle metal with a melting point of 6400C. The main methods of influencing the body are the gradual formation of oncological diseases, accumulation in the 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 type of metal is so widely used 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 storage batteries, the service life of which can reach five years.
Uranium 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:
In nature, this metal is light gray in color, has a melting point of over 11000C. Found in minerals:
- Uranium mica.
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, capable of rapidly decaying with the release of energy. So, it is used:
- in geochemistry;
- 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.
The most important of the metals following uranium in the periodic table are those that were discovered quite 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 higher 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 to prove itpractically scientists from different countries cannot since 1974. The last attempt was made in 2005, but was not confirmed by the general council of chemists.
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 application in nuclear power is not based on the ability to emit a huge amount of thermal energy during decay. The peculiarity is that thorium nuclei are able to capture neutrons and turn 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.
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 is found in nature as part of 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.
Also used for air ionization, eliminating static electricity in the room, in the manufacture of spaceheaters and other similar items.
Effect 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, every radioactive metal is a great danger to humans, especially if we talk about them in their pure form. Do not touch them with unprotected hands and be indoors with them without special protective equipment.