Inert gases, which are also called noble,occupy the main subgroup of the eighth group of the periodic system. There are only six of them: helium (He), neon (Ne), argon (Ar), xenon (Xe) and radon (Rn). To understand nature, first consider the concept of inertia. Inertness is a weak expression or lack of ability to react with other chemical elements. To cause a chemical reaction for the formation of new bonds in such substances is almost impossible.
Accordingly, inert gas is rarenoble monatomic gas with high inertness, which is caused by the energy-stable external level of the electron shell of an atom. For example, in helium, there are two electrons in this shell, and eight in other noble gases. This explains their physical and chemical properties. All inert gases under normal conditions are colorless, odorless and poorly soluble in water. Their boiling and melting points increase as the size of atoms increases.
Until 1962, scientists were confident that allnoble gases are completely inert. But the Canadian chemist N. Bartlett was able to prove the opposite, having received the first chemical compound of xenon, the so-called xenon hexafluoroplatinate. This compound is an orange solid with a crystal lattice. In the future, a number of compounds was significantly expanded.
Prevalence and education in nature
In the universe of noble gases mostHelium is common, and in terrestrial conditions - argon (by volume, it occupies 0.934%). In very small quantities, inert gases are found in rocks and gases of natural combustible materials, and in a dissolved form they can be found in oil and water.
Under natural conditions, noble gases canformed as a result of various nuclear reactions. For example, the source of radon are radioactive uranium preparations. Some of these chemical elements are of cosmogenic origin.
All inert gases, except rhodon, have a number of isotopes.
The reserves of these gases are not reduced. Only helium gradually, very slowly, dissipates in interstellar space.
Application
Inert gases are widely used in the field ofelectrical engineering. Argon, due to its inactivity and low thermal conductivity, is used in a mixture with nitrogen for filling electric lamps. Argon and neon fill tubes for illuminated advertisements, while they glow blue, and neon - orange-red.
Argon is also used in the chemical laboratory.practice. In industry, it has found its application for the heat treatment of easily oxidizable metals. Argon creates a protective atmosphere in which it is possible to weld or cut rare and non-ferrous metals, to melt tungsten, titanium, and zirconium. To control the ventilation systems used radioactive isotope argon.
Krypton and xenon have even lower thermal conductivity than argon, therefore the electric lamps filled by them are more durable and more economical than those filled with nitrogen or argon.
Divers breathe a mixture of helium and oxygen thatallows you to significantly lengthen the time of their stay under water and dramatically reduces the painful phenomena caused by pressure changes when rising to the surface.
Liquid helium is used as a refrigerant in various studies, since the boiling point of this gas is -268.9 ° C.
The property of complete inertness of helium is used forconducting welding in its atmosphere, for the production of ultrapure metals, chromatography. And its high permeability allowed to create leak detectors in low and high pressure devices.
