Among all the elements of the periodic system belongs to such a significant portion of which most people say fear.And how could it be otherwise?Because they are radioactive, which means a direct threat to human health.
try to understand what exactly the elements are dangerous and that they are, and find out what their harmful effects on the human body.
general concept of a group of radioactive elements
This group includes metals.They are many, they are located in the periodic table, and immediately after the lead up to the last cell.The main criterion by which decided to attribute this or that element of the group of radioactive - is its ability to have a certain half-life.
In other words, the radioactive decay - the transformation of the metal core to another subsidiary, which is accompanied by the emission of radiation of a certain type.This transformation occurs one element into another.
radioactive metals - is one that has at least one isotope is not.Even if all species will have six, and thus only one of them will support this property, the whole element will be considered radioactive.
types of radiation
main variants of radiation that is emitted from the decay of metals are:
- alpha particles;
- beta particle or neutrino decay;
- isomeric transition (gamma rays).
There are two variants of the existence of such elements.First - this is a natural, ie, when the radioactive metal found in nature, and the easiest way under the influence of external forces over time is converted into other forms (manifests its radioactivity decays).
second group - is artificially created by scientists metals capable of rapid disintegration and powerful release of large amounts of radiation.This is done for use in certain areas.Plants in which the nuclear reactions produced by the transformation of one element into another, called synchrotron.
marked difference between the two ways half-life is obvious: in both cases, it is spontaneous, but only artificially produced metal give it nuclear reactions in the process of deconstruction.
Basics designate like atoms
Since most of the elements of only one or two isotopes are radioactive, taken to indicate when a particular type of notation, not the entire unit as a whole.For example, the lead - it's just stuff.If take into account that it - a radioactive metal, then it should be called, for example, "Lead-207."
The half-lives of the particles can vary.There are isotopes which exist only 0.032 seconds.But along with them there are also those that fall for millions of years in the Earth's interior.
radioactive metals: List
complete list of all belonging to the considered group of elements can be quite impressive, because it includes all 80 metals.First of all it's standing in the periodic table after the lead, including the group of lanthanides and actinides.That is, bismuth, polonium, astatine, radon, francium, radium, Rutherford and so on through the serial number.
above the marked boundary is a set of representatives, each of whom also has isotopes.However, some of them may be just radioactive.Therefore, it is important what species has chemical element.The radioactive metal, or rather one of its isotopic species have virtually every member of the table.For example, they have:
- calcium;
- selenium;
- hafnium;
- tungsten;
- osmium;
- bismuth;
- indium;
- potassium;
- rubidium;
- zirconium;
- Europe;
- radium and others.
Thus, it is obvious that the elements that exhibit properties of radioactivity, so many - the vast majority.Some of them are safe because of the very long half-life and found in nature, while the other is artificially created by man for a variety of needs in science and technology and is extremely dangerous for the body of people.
features radium
element name given by its discoverer - the Curies, Pierre and Marie.These people first discovered that one of the isotopes of the metal - radium-226 - is the most stable form, have special properties of radioactivity.This happened in 1898, and a similar phenomenon only became known.Details of his study just do spouses chemists.
etymology takes roots in the French language, which it sounds like radium.Total 14 known isotopic modifications of the element.But the most stable forms of mass numbers:
- 220;
- 223;
- 224;
- 226;
- 228.
clearly expressed form of radioactivity has 226. By itself, radium - a chemical element at number 88. The atomic mass of [226].As simple substance capable of existence.It is a silvery-white radioactive metal with a melting point of about 6700S.
From a chemical point of view shows a sufficiently high degree of activity and is able to react with:
- water;
- organic acids to form stable complexes;
- oxygen to form an oxide.
Properties and application
also radium - a chemical element that forms a number of salts.Known its nitrides, chlorides, sulfates, nitrates, carbonates, phosphates, chromates.There is also a double salts with tungsten and beryllium.
What radium-226 can be hazardous to health, its discoverer Pierre Curie learned immediately.However, I managed to see this, when conducted an experiment: he went to the night tied to the upper arm tubes with metal.At the point of contact with the skin there was not healing ulcer, which get rid of the scientist could not more than two months.From their experiments on the phenomenon of radioactivity wife have not given up, however, and died, both from a large dose of radiation.
addition to a negative value, there are a number of areas where radium-226 is used and benefits:
- indicator level shifting ocean waters.
- used to determine the amount of uranium in the rock.
- Included in the lighting blends.
- The medicine is used to generate therapeutic radon baths.
- is used to remove the electric charges.
- With it carried out inspection of casting and welded seams detail.
Plutonium and its isotopes
This element was discovered in the forties of the XX century American scientists.It was first isolated from the uranium ore in which it was formed from Neptune.Last in this case - the result of the collapse of the uranium nucleus.That is, they are all closely linked to each other by common radioactive transformations.
There are several stable isotopes of the metal.However, the most common and important species are virtually plutonium-239.There are chemical reactions of metal:
- oxygen,
- acids;
- water;
- alkalis;
- halogens.
The physical properties of plutonium-239 is a brittle metal with a melting point 6400S.The main methods of influence on the body - is the gradual formation of cancer, the accumulation in the bones and the evocation of destruction of lung disease.
Field of use - mostly nuclear industry.It is known that the decay of plutonium-239 grams allocated an amount of heat which is comparable with 4 tons of coal burnt.That is why this type of metal is widely used in such reactions.Nuclear-grade plutonium - a source of energy in nuclear reactors and thermonuclear bombs.It is also used in the production of electrical energy storage devices, the service life can reach five years.
Uranus - radiation source
This element was discovered in 1789 by a chemist from Germany Klaproth.However, to investigate its properties and learn how to apply them in practice people have managed only in the XX century.The main distinguishing feature is that radioactive uranium is capable of forming the natural decay of the nucleus:
- lead-206;
- krypton;
- plutonium-239;
- lead-207;
- xenon.
In nature, this metal is light gray in color, has a melting point of over 11000S.It is found in the composition of minerals:
- Uranium micaceous hematite.
- Uraninite.
- pitchblende.
- Autun.
- Tyuyanmunit.
are three stable isotopes of natural and artificially synthesized 11, with mass numbers from 227 to 240.
The industry is widely used radioactive uranium that can quickly disintegrate, releasing energy.For example, it is used:
- in geochemistry;
- mining;
- nuclear reactors;
- in the manufacture of nuclear weapons.
Influence on the human body is no different from the previous review - metal accumulation leading to increased radiation dose and the occurrence of cancer.
transuranic elements
The most important metal standing behind uranium in the periodic table are those that have been opened recently.Just in 2004, came out sources confirming the birth of the light element 115 of the periodic system.
They became the most radioactive metal from all known today - Ununpentium (Uup).Its properties are not studied until now, because the half-life of 0.032 seconds!Review and identify the details of the structure and are particularly under such conditions is impossible.
However, its radioactivity is many times greater than the second performance on the property element - plutonium.However, in practice not used Ununpentium and a "slow" it mates table - uranium, plutonium, neptunium, polonium, and others.
Another element - unbiby - theoretically exists, but to prove it practically scientists from different countries can not since 1974.The last attempt was made in 2005, but was not confirmed by the general council chemists.
Thorium was discovered in the XIX century, Berzelius and named after the Norse god Thor.It is weakly radioactive metal.This feature have five of his 11-year-isotopes.
main application of nuclear power is not based on the ability to emit large amounts of heat from the decay.The peculiarity is that the thorium nucleus capable of capturing neutrons and transformed into uranium-238 and plutonium-239, which is already directly and enter into nuclear reactions.Therefore, thorium can be attributed to the group under consideration metals.
Polonius
silvery-white radioactive metal at number 84 in the periodic table.Was opened by the same ardent researchers radioactivity and everything connected with it, the couple Marie and Pierre Curie in 1898.The main feature of this material is that it is free, there are about 138.5 days.That is, this is the half-life of a given metal.
occurs naturally as a part of uranium and other ores.It is used as an energy source, and quite powerful.It is a strategic metal, as used for the manufacture of nuclear weapons.The number is strictly limited and is under the control of each state.
also used to ionize the air, eliminate static electricity in the room, in the manufacture of space heaters and other similar items.
effect on the human
All radioactive metals have the ability to penetrate human skin and accumulate in the body.They are very poorly displayed with waste products, do not appear to sweat.
With time beginning to infect the respiratory, circulatory, nervous system, causing irreversible changes in them.Effects on cells, causing them to not function properly.The result is the formation of malignant tumors, cancers arise.
Therefore, each radioactive metal - a great danger to humans, especially if we talk about them in a pure form.Do not touch them with bare hands and stay in the room with them without any special protective devices.
