Inert gases, which are also called noble gases, 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 we consider the concept of inertia. Inertness is a weak severity or lack of ability to react with other chemical elements. It is practically impossible to induce a chemical reaction to form new bonds in such substances.
Accordingly, an inert gas is a rare noble monatomic gas with a high inertness, which is due to the energy-stable external level of the electron shell of the atom. For example, helium has two electrons in this shell, while other noble gases have eight. This explains their physical and chemical properties. All inert gases under normal conditions are colorless gases, odorless and poorly soluble in water. Their boiling and melting points increase in accordance with the increase in atomic sizes.
Until 1962, scientists were convinced that all the noble gases were completely inert. But the Canadian chemist N. Bartlett was able to prove the opposite by obtaining the first chemical compound of xenon, the so-called xenon hexafluoroplatinate. This compound is a solid orange crystal lattice substance . Subsequently, a number of compounds were significantly expanded.
Prevalence and education in nature
Of the noble gases, helium is most abundant in the Universe, and argon is the most abundant in terrestrial conditions (it occupies 0.934% in volume). In very small quantities, inert gases are found in rocks and in gases of natural combustible materials, and in dissolved form they can be found in oil and water.
Under natural conditions, noble gases can form as a result of various nuclear reactions. For example, a source of radon is radioactive uranium. Some of these chemical elements are of cosmogenic origin.
All inert gases except rhodon have a number of isotopes.
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 of electrical engineering. Argon, due to its inactivity and low thermal conductivity, is used in a mixture with nitrogen to fill electric lamps. Argon and neon are filled with tubes for illuminated signs, while they glow blue, and neon ones glow orange-red.
Still argon is used in chemical laboratory practice. In industry, it has found its application for the heat treatment of easily oxidized metals. Argon creates a protective atmosphere in which it is possible to weld or cut rare and non-ferrous metals, and to melt tungsten, titanium, zirconium. To control ventilation systems, a radioactive argon isotope is used.
Krypton and xenon have even lower thermal conductivity than argon, so electric lamps filled with them are more durable and more economical than those filled with nitrogen or argon.
Divers breathe a mixture of helium and oxygen, which can significantly lengthen their time under water and dramatically weaken 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 inertia of helium is used for welding in its atmosphere, for the production of ultrapure metals, and chromatography. And its high permeability allowed the creation of leak detectors in low and high pressure apparatuses.