What number is the atomic number of hydrogen. What kind of substance is hydrogen? Chemical and physical properties of hydrogen

Hydrogen(lat.hydrogenium), H, chemical element, the first by the ordinal number in the periodic system of Mendeleev; atomic mass 1.00797. At normal conditions V. - gas; has no color, smell or taste.

Historical reference. In the works of chemists of the 16th and 17th centuries. the release of combustible gas under the action of acids on metals has been repeatedly mentioned. In 1766 G. Cavendish collected and investigated the released gas, calling it "combustible air". Being a supporter of the theory phlogiston, Cavendish believed that this gas is pure phlogiston. In 1783 A. Lavoisier by analyzing and synthesizing water, he proved the complexity of its composition, and in 1787 he defined "combustible air" as a new chemical element (B.) and gave it the modern name hydrog e ne (from the Greek hydor - water and genn ao - I give birth), which means "Giving birth to water"; this root is used in the names of B.'s compounds and processes with its participation (for example, hydrides, hydrogenation). The modern Russian name "V." was proposed by M.F.Soloviev in 1824.

Prevalence in nature ... V. is widespread in nature; its content in the earth's crust (lithosphere and hydrosphere) is 1% by mass and 16% by the number of atoms. V. is a part of the most widespread substance on Earth - water (11.19% of V. by mass), in the composition of compounds that make up coals, oil, natural gases, clays, as well as organisms of animals and plants (that is, in the composition of proteins, nucleic acids, fats, carbohydrates, etc.). In a free state, V. is extremely rare, in not large quantities it is found in volcanic and other natural gases. Minor amounts of free V. (0.0001% in terms of the number of atoms) are present in the atmosphere. In near-earth space, V. in the form of a flux of protons forms an internal ("proton") radiation belt of the earth... In space, V. is the most widespread element. As plasma it makes up about half the mass of the Sun and most stars, the bulk of the gases of the interstellar medium and gaseous nebulae. V. is present in the atmosphere of a number of planets and in comets in the form of free h 2, methane ch 4, ammonia nh 3, water h 2 o, radicals such as ch, nh, oh, sih, ph, etc. In the form of a flux of protons, V. is part of the corpuscular radiation of the sun and cosmic rays.

Isotopes, atom and molecule. Ordinary V. consists of a mixture of two stable isotopes: light V., or protium (1 h), and heavy V., or deuterium(2 h, or d). In natural hydrogen compounds, there are, on average, 6800 atoms 1 h per 1 atom 2 h. An artificially obtained radioactive isotope - superheavy V., or tritium(3 h, or T), with soft γ-radiation and half-life t 1/2= 12.262 years. In nature, tritium is formed, for example, from atmospheric nitrogen under the action of cosmic ray neutrons; in the atmosphere, it is negligible (4 · 10 -15% of the total number of V. atoms). The extremely unstable isotope 4 h was obtained. The mass numbers of isotopes 1 h, 2 h, 3 h and 4 h, respectively 1,2, 3 and 4, indicate that the nucleus of the protium atom contains only 1 proton, deuterium - 1 proton and 1 neutron, tritium - 1 proton and 2 neutrons, 4 h - 1 proton and 3 neutrons. The large difference in the masses of the isotopes of V. results in a more noticeable difference in their physical and chemical properties than in the case of isotopes of other elements.

Atom V. has the simplest structure among the atoms of all other elements: it consists of a nucleus and one electron. The binding energy of an electron with a nucleus (ionization potential) is 13.595 ev... A neutral atom B. can also attach a second electron, forming negative ion H -; in this case, the binding energy of the second electron with a neutral atom (electron affinity) is 0.78 ev. Quantum mechanics allows you to calculate all possible energy levels atom V., and therefore, give a complete interpretation of its atomic spectrum... The atom of V. is used as a model one in quantum-mechanical calculations of the energy levels of other, more complex atoms. Molecule B. h 2 consists of two atoms connected by a covalent chemical bond. The energy of dissociation (i.e. decay into atoms) is 4.776 ev(1 ev= 1.60210 10 -19 j). The interatomic distance at the equilibrium position of the nuclei is 0.7414 · a. At high temperatures, molecular V. dissociates into atoms (the degree of dissociation at 2000 ° C is 0.0013, and at 5000 ° C is 0.95). Atomic V. is also formed in various chemical reactions (for example, the action of zn on hydrochloric acid). However, the existence of V. in the atomic state lasts only a short time, the atoms recombine into molecules h 2.

Physical and Chemical properties ... V. - the lightest of all known substances (14.4 times lighter than air), density 0.0899 g / l at 0 ° C and 1 atm... V. boils (liquefies) and melts (solidifies) at -252.6 ° C and -259.1 ° C, respectively (only helium has lower melting and boiling points). The critical temperature of B. is very low (-240 ° C), and therefore its liquefaction is fraught with great difficulties; critical pressure 12.8 kgf / cm 2 (12,8 atm), critical density 0.0312 g / cm 3. Of all gases, V. has the highest thermal conductivity, equal at 0 ° C and 1 atm 0,174 Tue /(m· TO), i.e. 4.16 · 0 -4 feces /(with· cm· ° C). The specific heat capacity of V. at 0 ° C and 1 atmC p 14.20810 3 j /(Kg· TO), i.e. 3.394 feces /(G· ° C). B. slightly soluble in water (0.0182 ml / g at 20 ° C and 1 atm), but good - in many metals (ni, pt, pd, etc.), especially in palladium (850 volumes per 1 volume pd). The solubility of V. in metals is associated with its ability to diffuse through them; diffusion through a carbonaceous alloy (for example, steel) is sometimes accompanied by the destruction of the alloy due to the interaction of carbon with carbon (the so-called decarbonization). Liquid V. is very light (density at -253 ° C 0.0708 g / cm 3) and fluid (viscosity at - 253 ° C 13.8 spoise).

In most compounds, valence (more precisely, the oxidation state) +1, like sodium and other alkali metals; usually it is considered as an analogue of these metals, heading 1 gr. systems of Mendeleev. However, in metal hydrides, the hydrogen ion is negatively charged (oxidation state -1), i.e., the hydride na + h - is constructed like the chloride na + cl -. This and some other facts (the closeness of the physical properties of V. and halogens, the ability of halogens to replace V. in organic compounds) give reason to assign V. also to the vii group of the periodic system. Under ordinary conditions, molecular V. is comparatively little active, combining directly only with the most active non-metals (with fluorine, and in the light and with chlorine). However, when heated, it reacts with many elements. Atomic V. has increased chemical activity in comparison with molecular one. With oxygen, V. forms water: h 2 + 1/2 o 2 = h 2 o with the release of 285.937 · 10 3 j / mol, i.e. 68.3174 kcal / mol heat (at 25 ° C and 1 atm). At ordinary temperatures, the reaction proceeds extremely slowly, above 550 ° C - with an explosion. The explosion limits of the hydrogen-oxygen mixture are (by volume) from 4 to 94% h 2, and the hydrogen-air mixture - from 4 to 74% h 2 (a mixture of 2 volumes of h 2 and 1 volume of O 2 is called oxyhydrogen gas). V. is used for the reduction of many metals, since it takes oxygen from their oxides:

cuo + H 2 = cu + h 2 o,

fe 3 o 4 + 4h 2 = 3fe + 4h 2 o, etc.

With halogens, V. forms hydrogen halides, for example:

h 2 + cl 2 = 2hcl.

At the same time, V. explodes with fluorine (even in the dark and at -252 ° C), reacts with chlorine and bromine only when illuminated or heated, and with iodine only when heated. V. interacts with nitrogen to form ammonia: 3h 2 + n 2 = 2nh 3 only on the catalyst and at elevated temperatures and pressures. When heated, V. reacts vigorously with sulfur: h 2 + s = h 2 s (hydrogen sulfide), much more difficult with selenium and tellurium. With pure carbon V. can react without a catalyst only at high temperatures: 2h 2 + C (amorphous) = ch 4 (methane). V. directly reacts with certain metals (alkali, alkaline-earth, etc.), forming hydrides: h 2 + 2li = 2lih. Of great practical importance are the reactions of iron with carbon monoxide, in which, depending on the temperature, pressure, and catalyst, various organic compounds, for example hcho, ch 3 oh, etc. Unsaturated hydrocarbons react with V., passing into saturated ones, for example:

c n h 2 n + h 2 = c n h 2 n +2.

The role of V. and its compounds in chemistry is exceptionally great. V. conditions acidic properties so-called protic acids. V. is inclined to form with some elements the so-called hydrogen bond, which has a decisive influence on the properties of many organic and inorganic compounds.

Receiving ... The main types of raw materials for industrial production of V. - natural combustible gases, coke oven gas(cm. Coke chemistry) and refinery gases and also products of gasification of solid and liquid fuels (mainly coal). V. is also obtained from water electrolysis (in places with cheap electricity). The most important methods of production of V. from natural gas are the catalytic interaction of hydrocarbons, mainly methane, with steam (conversion): ch 4 + h 2 o = co + 3h 2, and incomplete oxidation of hydrocarbons with oxygen: ch 4 + 1/2 o 2 = co + 2h 2. The resulting carbon monoxide also undergoes conversion: co + h 2 o = co 2 + h 2. V., extracted from natural gas, is the cheapest. A very widespread method of producing coal is from water and steam-air gases produced by coal gasification. The process is based on the conversion of carbon monoxide. Water gas contains up to 50% h 2 and 40% co; in the vapor-air gas, in addition to h 2 and co, there is a significant amount of n 2, which is used together with the obtained V. for the synthesis of nh 3. V. is isolated from coke oven gas and petroleum-refining gases by removing the remaining components of the gas mixture, which are liquefied more easily than V. by deep cooling. Water electrolysis is carried out direct current by passing it through a koh or naoh solution (acids are not used to avoid corrosion of the steel apparatus). In laboratories, V. is obtained by electrolysis of water, and also by the reaction between zinc and hydrochloric acid. However, more often they use ready-made factory V. in cylinders.

Application ... V. began to be produced on an industrial scale at the end of the 18th century. for filling balloons. At present, V. is widely used in the chemical industry, mainly for the production of ammonia... A large consumer of alcohol is also the production of methyl and other alcohols, synthetic gasoline (synthine), and other products obtained by synthesis from alcohol and carbon monoxide. V. is used for the hydrogenation of solid and heavy liquid fuels, fats, etc., for the synthesis of hcl, for the hydrotreating of petroleum products, in welding and cutting metals with an oxygen-hydrogen flame (temperatures up to 2800 ° C), and in atomic hydrogen welding(up to 4000 ° C). Vitamin isotopes — deuterium and tritium — have found very important applications in atomic energy.

Lit .: Nekrasov B.V., Course of General Chemistry, 14th ed., M., 1962; Remy G., Course in inorganic chemistry, trans. from it., t. 1, M., 1963; Egorov A.P., Shereshevsky D.I., Shmanenkov I.V., General chemical technology not organic matter, 4th ed., M., 1964; General chemical technology. Ed. S. I. Volfkovich, t. 1, M., 1952; Lebedev VV, Hydrogen, its receipt and use, M., 1958; Nalbandyan A.B., Voevodsky V.V., Mechanism of oxidation and combustion of hydrogen, M. - L., 1949; Brief chemical encyclopedia, vol. 1, M., 1961, p. 619-24.

The most abundant chemical element in the Universe is hydrogen. This is a kind of starting point, because in the periodic table, its atomic number is equal to one. Humanity hopes to be able to learn more about it as one of the most possible vehicles in the future. Hydrogen is the simplest, lightest, most widespread element, there is a lot of it everywhere - seventy-five percent of the total mass of matter. It is found in any star, especially a lot of hydrogen in gas giants. Its role in stellar fusion reactions is key. Without hydrogen, there is no water, which means there is no life. Everyone remembers that a water molecule contains one oxygen atom, and two atoms in it - hydrogen. This is for everyone famous formula H 2 O.

How we use it

Discovered hydrogen in 1766 by Henry Cavendish when he was analyzing the oxidation reaction of a metal. After several years of observation, he realized that in the process of burning hydrogen, water is formed. Previously, scientists isolated this element, but did not consider it independent. In 1783, hydrogen received the name hydrogen (translated from the Greek "hydro" - water, and "gene" - to give birth). The element that generates water is hydrogen. It is a gas whose molecular formula is H 2. If the temperature is close to room temperature, and the pressure is normal, this element is imperceptible. Hydrogen may not even be caught by human senses - it is tasteless, colorless, odorless. But under pressure and at a temperature of -252.87 C (very cold!), This gas liquefies. This is how it is stored, since it takes up much more space in the form of gas. It is liquid hydrogen that is used as propellant.

Hydrogen can become solid, metallic, but this requires ultra-high pressure, and this is what the most prominent scientists - physicists and chemists - are doing now. Already now this element serves alternative fuel for transport. Its use is similar to how an internal combustion engine works: when hydrogen is burned, a lot of its chemical energy is released. A method for creating a fuel cell based on it has also been practically developed: when combined with oxygen, a reaction occurs, and through this, water and electricity are formed. Perhaps, soon transport will "switch" instead of gasoline to hydrogen - a lot of car manufacturers are interested in the creation of alternative combustible materials, there are also successes. But a purely hydrogen engine is still in the future, there are many difficulties here. However, the advantages are such that the creation of a fuel tank with solid hydrogen is in full swing, and scientists and engineers are not going to retreat.

Basic information

Hydrogenium (lat.) - hydrogen, the first serial number in the periodic table, denoted by H. The hydrogen atom has a mass of 1.0079, it is a gas that under normal conditions has neither taste, nor smell, nor color. Chemists since the sixteenth century have described a certain combustible gas with different names. But it turned out for everyone under the same conditions - when an acid acts on the metal. For many years, hydrogen was simply called "combustible air" by the Cavendish himself. Only in 1783 Lavoisier proved that water has a complex composition, through synthesis and analysis, and four years later he also gave "combustible air" its modern name. The root of this complex word is widely used when it is necessary to name the compounds of hydrogen and any processes in which it participates. For example, hydrogenation, hydride, and the like. And the Russian name was suggested in 1824 by M. Solovyov.

In nature, the distribution of this element is unmatched. In the lithosphere and hydrosphere of the earth's crust, its mass is one percent, but hydrogen atoms are as much as sixteen percent. The most widespread on Earth is water, and 11.19% by mass in it is hydrogen. It is also invariably present in almost all compounds of which oil, coal, all natural gases, and clay are composed. There is hydrogen in all organisms of plants and animals - in the composition of proteins, fats, nucleic acids, carbohydrates, and so on. The free state for hydrogen is not typical and almost never occurs - there is very little of it in natural and volcanic gases. An absolutely insignificant amount of hydrogen in the atmosphere - 0.0001%, by the number of atoms. On the other hand, whole streams of protons represent hydrogen in near-earth space, it consists of the inner radiation belt of our planet.

Space

In space, no element occurs as often as hydrogen. The volume of hydrogen in the elements of the Sun is more than half of its mass. Most stars form hydrogen, which is in the form of plasma. The bulk of the various gases in nebulae and in the interstellar medium also consist of hydrogen. It is present in comets, in the atmosphere of a number of planets. Naturally, not in its pure form, either as free H 2, then as methane CH 4, then as ammonia NH 3, even as water H 2 O. Radicals CH, NH, SiN, OH, PH and the like are very common. As a flux of protons, hydrogen is part of the corpuscular solar radiation and cosmic rays.

In ordinary hydrogen, a mixture of two stable isotopes is light hydrogen (or protium 1 H) and heavy hydrogen (or deuterium - 2 H or D). There are other isotopes: radioactive tritium - 3 H or T, otherwise - superheavy hydrogen. And also a very unstable 4 N. In nature, a hydrogen compound contains isotopes in the following proportions: there are 6800 protium atoms per deuterium atom. Tritium is formed in the atmosphere from nitrogen, which is influenced by cosmic ray neutrons, but is negligible. What do isotope mass numbers stand for? The figure indicates that the protium nucleus has only one proton, while deuterium has not only a proton, but also a neutron in the atomic nucleus. Tritium in the nucleus has two neutrons to one proton. But 4 N contains three neutrons per proton. That's why physical properties and chemical isotopes of hydrogen are very different in comparison with isotopes of all other elements - too great a difference in mass.

Structure and physical properties

The structure of the hydrogen atom is the simplest in comparison with all other elements: one nucleus - one electron. Ionization potential - the binding energy of a nucleus with an electron - 13.595 electron volts (eV). It is because of the simplicity of this structure that the hydrogen atom is convenient as a model in quantum mechanics when it is necessary to calculate the energy levels of more complex atoms. In the H2 molecule there are two atoms that are connected by a chemical covalent bond... The decay energy is very high. Atomic hydrogen can be formed in chemical reactions such as zinc and hydrochloric acid. However, there is practically no interaction with hydrogen - the atomic state of hydrogen is very short, the atoms immediately recombine into H2 molecules.

From a physical point of view, hydrogen is lighter than all known substances - more than fourteen times lighter than air (remember the balloons flying away at the holidays - they have just hydrogen inside). However, he knows how to boil, liquefy, melt, solidify, and only helium boils and melts at more low temperatures... It is difficult to liquefy it, you need a temperature below -240 degrees Celsius. But it has a very high thermal conductivity. It almost does not dissolve in water, but the interaction with hydrogen of metals is excellent - it dissolves in almost all, best of all in palladium (one volume of hydrogen takes eight hundred and fifty volumes). Liquid hydrogen is light and fluid, and when it dissolves in metals, it often destroys alloys due to interaction with carbon (steel, for example), diffusion, decarbonization occurs.

Chemical properties

In compounds, for the most part, hydrogen shows an oxidation state (valence) of +1, like sodium and other alkali metals. He is considered as their analogue, standing at the head of the first group of the Mendeleev system. But the hydrogen ion in metal hydrides is negatively charged, with an oxidation state of -1. Also, this element is close to halogens, which are even capable of replacing it in organic compounds. This means that hydrogen can be attributed to the seventh group of the Mendeleev system. Under normal conditions, hydrogen molecules do not differ in activity, combining only with the most active non-metals: good with fluorine, and if light - with chlorine. But when heated, hydrogen becomes different - it reacts with many elements. Compared to molecular hydrogen, atomic hydrogen is very active chemically, because in connection with oxygen, water is formed, and energy and heat are released along the way. At room temperature, this reaction is very slow, but when heated above five hundred and fifty degrees, an explosion occurs.

Hydrogen is used to reduce metals, because it takes oxygen away from their oxides. With fluorine, hydrogen forms an explosion even in the dark and at minus two hundred and fifty-two degrees Celsius. Chlorine and bromine excite hydrogen only when heated or illuminated, and iodine only when heated. Hydrogen with nitrogen forms ammonia (this is how most fertilizers are produced). When heated, it very actively interacts with sulfur, and hydrogen sulfide is obtained. Tellurium and selenium are difficult to react with hydrogen, but pure carbon reacts at very high temperatures to produce methane. With carbon monoxide, hydrogen forms various organic compounds, pressure, temperature, catalysts affect here, and all this is of great practical importance. And in general, the role of hydrogen, as well as of its compounds, is extremely great, since it gives acidic properties to protic acids. A hydrogen bond is formed with many elements, which affects the properties of both inorganic and organic compounds.

Receiving and using

Hydrogen is obtained on an industrial scale from natural gases - combustible, coke oven, petroleum refining gases. It can also be obtained by electrolysis where electricity is not too expensive. However, the most important method of hydrogen production is the catalytic interaction of hydrocarbons, mostly methane, with steam when conversion is obtained. The method of oxidation of hydrocarbons with oxygen is also widely used. Extraction of hydrogen from natural gas is the cheapest method. The other two are the use of coke oven gas and refinery gas - hydrogen is released when the remaining components are liquefied. They lend themselves more easily to liquefaction, and for hydrogen, as we remember, you need -252 degrees.

Hydrogen peroxide is very popular in use. Treatment with this solution is used very often. Molecular Formula H 2 O 2 is unlikely to be named by all those millions of people who want to be blonde and lighten their hair, as well as those who love cleanliness in the kitchen. Even those who treat scratches from playing with a kitten are often unaware that they are using hydrogen treatment. But everyone knows the story: since 1852, hydrogen has been used for a long time in aeronautics. The airship, invented by Henry Giffard, was based on hydrogen. They were called zeppelins. The rapid development of aircraft construction drove the zeppelins out of the sky. In 1937, there was a major accident when the Hindenburg airship burned down. After this incident, the zeppelins were never used again. But at the end of the eighteenth century, the proliferation of balloons filled with hydrogen was widespread. In addition to the production of ammonia, today hydrogen is needed for the manufacture of methyl alcohol and other alcohols, gasoline, hydrogenated heavy fuel oils and solid fuels. You cannot do without hydrogen when welding, when cutting metals - it can be oxygen-hydrogen and atomic-hydrogen. And tritium and deuterium give life to nuclear power. These are, as we remember, isotopes of hydrogen.

Neumyvakin

Hydrogen as a chemical element is so good that it could not help but have its own fans. Ivan Pavlovich Neumyvakin is a doctor of medical sciences, professor, laureate of the State Prize and he has many more titles and awards, among them. As a traditional medicine doctor, he was named the best folk healer in Russia. It was he who developed many methods and principles of providing medical assistance to astronauts in flight. It was he who created a unique hospital - a hospital on board a spacecraft. At the same time, he was the state coordinator for the field of cosmetic medicine. Space and cosmetics. His passion for hydrogen is not aimed at making big money, as is now the case in domestic medicine, but, on the contrary, is to teach people to cure anything from literally a penny means, without additional visits to pharmacies.

He promotes treatment with a drug that is present in literally every home. This is hydrogen peroxide. You can criticize Neumyvakin as much as you want, he will still insist on his own: yes, indeed, literally everything can be cured with hydrogen peroxide, because it saturates the internal cells of the body with oxygen, destroys toxins, normalizes acid and alkaline balance, and from here tissues are regenerated, the whole organism. So far, no one has seen the cured with hydrogen peroxide, much less examined, but Neumyvakin claims that using this remedy, you can completely get rid of viral, bacterial and fungal diseases, prevent the development of tumors and atherosclerosis, defeat depression, rejuvenate the body and never get sick SARS and colds.

Panacea

Ivan Pavlovich is sure that with the correct use of this simplest drug and with the observance of all the simple instructions, it is possible to defeat many diseases, among which there are very serious ones. The list is huge: from periodontal disease and tonsillitis to myocardial infarction, strokes and diabetes mellitus. Such trifles as sinusitis or osteochondrosis fly away from the first treatment sessions. Even cancerous tumors get scared and flee from hydrogen peroxide, because immunity is stimulated, the life of the body and its defenses are activated.

Even children can be treated in this way, except that it is better for pregnant women to refrain from using hydrogen peroxide for the time being. Also, this method is not recommended for people with transplanted organs due to possible tissue incompatibility. The dosage should be strictly observed: from one drop to ten, adding one every day. Three times a day (thirty drops of a three percent hydrogen peroxide solution per day, wow!) Half an hour before meals. The solution can be administered intravenously and under medical supervision. Sometimes hydrogen peroxide is combined for a more powerful effect with other drugs. Inside, the solution is used only in a diluted form - with clean water.

Outwardly

Compresses and rinses, even before Professor Neumyvakin created his methods, were very popular. Everyone knows that, just like alcohol compresses, hydrogen peroxide cannot be used in its pure form, because it will burn the tissues, but warts or fungal lesions are lubricated locally and with a strong solution - up to fifteen percent.

With skin rashes, with headaches, procedures are also performed in which hydrogen peroxide is involved. The compress should be done with a cotton cloth dipped in a solution of two teaspoons of three percent hydrogen peroxide and fifty milligrams pure water... Cover the fabric with foil and wrap it with wool or a towel. The time of action of the compress is from a quarter of an hour to an hour and a half in the morning and in the evening until recovery.

Opinion of doctors

Opinions are divided, not everyone is amazed by the properties of hydrogen peroxide, moreover, they are not only not believed, they are laughed at. Among the doctors are also those who supported Neumyvakin and even picked up the development of his theory, but they are in the minority. Most doctors consider such a treatment plan not only ineffective, but also often destructive.

Indeed, there is not yet a single officially proven case when a patient would have been cured with hydrogen peroxide. At the same time, there is no information about the deterioration of health in connection with the use of this method. But precious time is lost, and a person who has received one of the serious diseases and has completely relied on Neumyvakin's panacea runs the risk of being late for the start of his real traditional treatment.

Liquid

Hydrogen(lat. Hydrogenium; denoted by the symbol H) - the first element of the periodic table of elements. Widely distributed in nature. The cation (and nucleus) of the most abundant hydrogen isotope, 1 H, is the proton. The properties of the 1 H nucleus make it possible to widely use NMR spectroscopy in the analysis of organic substances.

Three isotopes of hydrogen have their own names: 1 H - protium (H), 2 H - deuterium (D) and 3 H - tritium (radioactive) (T).

Simple substance hydrogen - H 2 - light colorless gas. It is flammable and explosive when mixed with air or oxygen. Non-toxic. Let's dissolve in ethanol and a number of metals: iron, nickel, palladium, platinum.

History

The release of combustible gas during the interaction of acids and metals was observed in the 16th and 17th centuries at the dawn of the formation of chemistry as a science. Mikhail Vasilyevich Lomonosov also directly pointed to its separation, but already definitely realizing that it was not phlogiston. The English physicist and chemist Henry Cavendish investigated this gas in 1766 and called it "combustible air." When burned, the "combustible air" produced water, but Cavendish's adherence to the phlogiston theory prevented him from drawing correct conclusions. The French chemist Antoine Lavoisier, together with the engineer J. Meunier, using special gas meters, in 1783 synthesized water, and then analyzed it, decomposing water vapor with hot iron. Thus, he established that "combustible air" is part of water and can be obtained from it.

origin of name

Lavoisier gave hydrogen the name hydrogène - "giving birth to water." The Russian name "hydrogen" was proposed by the chemist M.F.

Prevalence

Hydrogen is the most abundant element in the universe. It accounts for about 92% of all atoms (8% are helium atoms, the share of all other elements taken together is less than 0.1%). Thus, hydrogen is the main component stars and interstellar gas. Under conditions of stellar temperatures (for example, the surface temperature of the Sun is ~ 6000 ° C), hydrogen exists in the form of plasma; in interstellar space, this element exists in the form of individual molecules, atoms and ions and can form molecular clouds that differ significantly in size, density and temperature.

Earth's crust and living organisms

The mass fraction of hydrogen in the earth's crust is 1% - this is the tenth most abundant element. However, its role in nature is determined not by mass, but by the number of atoms, the proportion of which among other elements is 17% (second place after oxygen, the proportion of atoms of which is ~ 52%). Therefore, the importance of hydrogen in the chemical processes taking place on Earth is almost as great as oxygen. Unlike oxygen, which exists on Earth in both bound and free states, practically all hydrogen on Earth is in the form of compounds; only a very small amount of hydrogen in the form of a simple substance is contained in the atmosphere (0.00005% by volume).

Hydrogen is a part of almost all organic substances and is present in all living cells. In living cells, hydrogen accounts for almost 50% of the number of atoms.

Receiving

Industrial methods of obtaining simple substances depend on the form in which the corresponding element is found in nature, that is, what can be the raw material for its production. So, oxygen, which is available in a free state, is obtained by a physical method - by separation from liquid air. Almost all hydrogen is in the form of compounds, therefore, chemical methods are used to obtain it. In particular, decomposition reactions can be used. One of the methods for producing hydrogen is the reaction of water decomposition by electric current.

The main industrial method for producing hydrogen is the reaction of methane with water, which is part of natural gas. It is carried out at high temperature(it is easy to make sure that when methane is passed even through boiling water, no reaction occurs):

CH 4 + 2H 2 O = CO 2 + 4H 2 −165 kJ

In the laboratory, to obtain simple substances, they do not necessarily use natural raw materials, but select those starting materials from which it is easier to isolate the required substance. For example, in a laboratory, oxygen is not obtained from the air. The same applies to the production of hydrogen. One of the laboratory methods for producing hydrogen, which is sometimes used in industry, is the decomposition of water with an electric current.

Usually in the laboratory, hydrogen is produced by the interaction of zinc with hydrochloric acid.

In industry

1.Electrolysis aqueous solutions salts:

2NaCl + 2H 2 O → H 2 + 2NaOH + Cl 2

2.Passing water vapor over red-hot coke at a temperature of about 1000 ° C:

H 2 O + C? H 2 + CO

3.From natural gas.

Steam conversion:

CH 4 + H 2 O? CO + 3H 2 (1000 ° C)

Catalytic oxidation with oxygen:

2CH 4 + O 2? 2CO + 4H 2

4. Cracking and reforming of hydrocarbons in the process of oil refining.

In the laboratory

1.The action of dilute acids on metals. To carry out such a reaction, zinc and dilute hydrochloric acid are most often used:

Zn + 2HCl → ZnCl 2 + H 2

2.Interaction of calcium with water:

Ca + 2H 2 O → Ca (OH) 2 + H 2

3.Hydrolysis of hydrides:

NaH + H 2 O → NaOH + H 2

4.The action of alkalis on zinc or aluminum:

2Al + 2NaOH + 6H 2 O → 2Na + 3H 2

Zn + 2KOH + 2H 2 O → K 2 + H 2

5.By electrolysis. During the electrolysis of aqueous solutions of alkalis or acids, hydrogen is evolved at the cathode, for example:

2H 3 O + + 2e - → H 2 + 2H 2 O

Physical properties

Hydrogen can exist in two forms (modifications) - in the form of ortho- and para-hydrogen. Orthohydrogen molecule o-H 2 (m.p. -259.10 ° C, bp. -252.56 ° C) nuclear spins are directed in the same way (parallel), p-H 2 (m.p. -259.32 ° C, bp. -252.89 ° C) - opposite to each other (antiparallel). Equilibrium mixture o-H 2 and p-H 2 at a given temperature is called equilibrium hydrogen e-H 2.

Hydrogen modifications can be separated by adsorption on active carbon at liquid nitrogen temperature. At very low temperatures, the equilibrium between orthohydrogen and parahydrogen is almost entirely shifted towards the latter. At 80 K, the ratio of forms is approximately 1: 1. Desorbed parahydrogen on heating is converted into orthohydrogen until a mixture equilibrium at room temperature is formed (ortho-pair: 75:25). Without a catalyst, the transformation occurs slowly (under conditions of the interstellar medium - with characteristic times up to cosmological), which makes it possible to study the properties of individual modifications.

Hydrogen is the lightest gas; it is 14.5 times lighter than air. It is obvious that the smaller the mass of the molecules, the higher their speed at the same temperature. As the lightest, hydrogen molecules move faster than molecules of any other gas and thus can transfer heat faster from one body to another. It follows that hydrogen has the highest thermal conductivity among gaseous substances. Its thermal conductivity is about seven times higher than the thermal conductivity of air.

The hydrogen molecule is diatomic - Н 2. Under normal conditions, it is a colorless, odorless and tasteless gas. Density 0.08987 g / l (n.u.), boiling point −252.76 ° C, specific heat of combustion 120.9 × 10 6 J / kg, slightly soluble in water - 18.8 ml / l. Hydrogen is readily soluble in many metals (Ni, Pt, Pd, etc.), especially in palladium (850 volumes per 1 volume of Pd). The solubility of hydrogen in metals is associated with its ability to diffuse through them; diffusion through a carbonaceous alloy (for example, steel) is sometimes accompanied by the destruction of the alloy due to the interaction of hydrogen with carbon (the so-called decarbonization). Practically insoluble in silver.

Liquid hydrogen exists in a very narrow temperature range from -252.76 to -259.2 ° C. It is a colorless liquid, very light (density at -253 ° C 0.0708 g / cm 3) and fluid (viscosity at -253 ° C 13.8 cpoise). The critical parameters of hydrogen are very low: the temperature is −240.2 ° C and the pressure is 12.8 atm. This explains the difficulties in liquefying hydrogen. In the liquid state, equilibrium hydrogen consists of 99.79% para-H 2, 0.21% ortho-H 2.

Solid hydrogen, melting point −259.2 ° C, density 0.0807 g / cm 3 (at −262 ° C) - snow-like mass, crystals of hexagonal system, space group P6 / mmc, cell parameters a=3,75 c= 6.12. At high pressure hydrogen transforms into a metallic state.

Isotopes

Hydrogen occurs in the form of three isotopes, which have individual names: 1 H - protium (H), 2 H - deuterium (D), 3 H - tritium (radioactive) (T).

Protium and deuterium are stable isotopes with mass numbers 1 and 2. Their content in nature is, respectively, 99.9885 ± 0.0070% and 0.0115 ± 0.0070%. This ratio may vary slightly depending on the source and method of producing hydrogen.

The hydrogen isotope 3 H (tritium) is unstable. Its half-life is 12.32 years. Tritium is found in nature in very small quantities.

The literature also provides data on hydrogen isotopes with mass numbers 4–7 and half-lives of 10–22–10–23 s.

Natural hydrogen consists of H 2 and HD (hydrogen deuteride) molecules in a ratio of 3200: 1. The content of pure deuterium hydrogen D 2 is even less. The ratio of the concentrations of HD and D 2 is approximately 6400: 1.

Of all the isotopes of chemical elements, the physical and chemical properties of hydrogen isotopes differ from each other the most. This is due to the largest relative change in atomic masses.

	Temperature melting, K	Temperature boiling, K	Triple point, K / kPa	Critical point, K / kPa	Density liquid / gas, kg / m³

Deuterium and tritium also have ortho and para modifications: p-D 2, o-D 2, p-T 2, o-T 2. Heteroisotopic hydrogen (HD, HT, DT) have no ortho and para modifications.

Chemical properties

Fraction of dissociated hydrogen molecules

The hydrogen molecules H 2 are quite strong, and a lot of energy must be expended in order for hydrogen to react:

H 2 = 2H - 432 kJ

Therefore, at ordinary temperatures, hydrogen reacts only with very active metals, for example with calcium, forming calcium hydride:

Ca + H 2 = CaH 2

and with the only non-metal - fluorine, forming hydrogen fluoride:

With most metals and non-metals, hydrogen reacts at elevated temperatures or under other influences, for example, under lighting:

О 2 + 2Н 2 = 2Н 2 О

It can “take” oxygen from some oxides, for example:

CuO + H 2 = Cu + H 2 O

The written equation reflects the reducing properties of hydrogen.

N 2 + 3H 2 → 2NH 3

Forms hydrogen halides with halogens:

F 2 + H 2 → 2HF, the reaction proceeds with an explosion in the dark and at any temperature,

Cl 2 + H 2 → 2HCl, the reaction proceeds with an explosion, only in the light.

Reacts with soot under strong heating:

C + 2H 2 → CH 4

Interaction with alkali and alkaline earth metals

When interacting with active metals, hydrogen forms hydrides:

2Na + H 2 → 2NaH

Ca + H 2 → CaH 2

Mg + H 2 → MgH 2

Hydrides- salty, solid substances, easily hydrolyzed:

CaH 2 + 2H 2 O → Ca (OH) 2 + 2H 2

Interaction with metal oxides (usually d-elements)

Oxides are reduced to metals:

CuO + H 2 → Cu + H 2 O

Fe 2 O 3 + 3H 2 → 2Fe + 3H 2 O

WO 3 + 3H 2 → W + 3H 2 O

Hydrogenation of organic compounds

Molecular hydrogen is widely used in organic synthesis for the reduction of organic compounds. These processes are called hydrogenation reactions... These reactions are carried out in the presence of a catalyst at high blood pressure and temperature. The catalyst can be either homogeneous (e.g. Wilkinson's catalyst) or heterogeneous (e.g. Raney nickel, palladium-carbon).

So, in particular, during the catalytic hydrogenation of unsaturated compounds such as alkenes and alkynes, saturated compounds are formed - alkanes.

Hydrogen Geochemistry

Free hydrogen H 2 is relatively rare in terrestrial gases, but in the form of water it plays an extremely important role in geochemical processes.

Hydrogen can be included in minerals in the form of ammonium ion, hydroxyl ion and crystal water.

In the atmosphere, hydrogen is continuously formed as a result of the decomposition of water by solar radiation. Having a small mass, hydrogen molecules have a high speed of diffusion motion (it is close to the second cosmic speed) and, falling into the upper layers of the atmosphere, can fly into outer space.

Features of treatment

When mixed with air, hydrogen forms an explosive mixture - the so-called explosive gas. This gas is most explosive when the volume ratio of hydrogen and oxygen is 2: 1, or hydrogen and air is approximately 2: 5, since the air contains about 21% oxygen. Also hydrogen is fire hazardous. Liquid hydrogen can cause severe frostbite if it comes into contact with the skin.

Explosive concentrations of hydrogen with oxygen occur from 4% to 96% by volume. When mixed with air from 4% to 75 (74)% by volume.

Economy

The cost of hydrogen for large-scale wholesale supplies fluctuates in the range of $ 2-5 per kg.

Application

Atomic hydrogen is used for atomic hydrogen welding.

Chemical industry

• In the production of ammonia, methanol, soap and plastics
• In the production of margarine from liquid vegetable oils
• Registered as a food additive E949(packing gas)

Food industry

Aviation industry

Hydrogen is very light and always rises up in the air. Once airships and Balloons filled with hydrogen. But in the 30s. XX century there were several disasters, during which the airships exploded and burned. Nowadays, airships are filled with helium, despite its significantly higher cost.

Fuel

Hydrogen is used as propellant.

Research is underway on the use of hydrogen as a fuel for cars and trucks. Hydrogen engines don't pollute the environment and emit only water vapor.

Hydrogen-oxygen fuel cells use hydrogen to directly convert energy chemical reaction into electric.

"Liquid hydrogen"("LH") is a liquid aggregate state of hydrogen, with a low specific density of 0.07 g / cm³ and cryogenic properties with a freezing point of 14.01 K (−259.14 ° C) and a boiling point of 20.28 K (−252.87 ° C). It is a colorless, odorless liquid which, when mixed with air, is classified as explosive with a flammability range of 4-75%. The spin ratio of isomers in liquid hydrogen is: 99.79% - parahydrogen; 0.21% - orthohydrogen. The expansion coefficient of hydrogen when changing the state of aggregation to gaseous is 848: 1 at 20 ° C.

As with any other gas, hydrogen liquefaction leads to a decrease in its volume. After liquefaction, "LH" is stored in thermally insulated containers under pressure. Liquid hydrogen (rus. Liquid hydrogen, LH2, LH 2) is actively used in industry, as a form of gas storage, and in the space industry, as a rocket fuel.

History

The first documented use of artificial cooling in 1756 was carried out by the English scientist William Cullen, Gaspard Monge was the first to obtain the liquid state of sulfur oxide in 1784, Michael Faraday was the first to obtain liquefied ammonia, the American inventor Oliver Evans was the first to develop refrigeration compressor in 1805, Jacob Perkins was the first to patent a cooling machine in 1834 and John Gorey was the first to patent an air conditioner in the United States in 1851. Werner Siemens proposed the concept of regenerative cooling in 1857, Karl Linde patented equipment for producing liquid air using the cascade Joule-Thomson expansion effect and regenerative cooling in 1876. In 1885, the Polish physicist and chemist Sigmund Wrobblewski published a critical temperature of 33 K for hydrogen and a critical pressure of 13.3 atm. and a boiling point at 23 K. Hydrogen was first liquefied by James Dewar in 1898 using regenerative refrigeration and his invention, the Dewar flask. The first synthesis of the stable isomer of liquid hydrogen - parahydrogen - was carried out by Paul Hartek and Karl Bonhoeffer in 1929.

Spin isomers of hydrogen

Hydrogen at room temperature consists mainly of the spin isomer, orthohydrogen. After production, liquid hydrogen is in a metastable state and must be converted to a parahydrogenic form in order to avoid the explosive exothermic reaction that occurs when it changes at low temperatures. Conversion to the parahydrogen phase is usually performed using catalysts such as iron oxide, chromium oxide, activated carbon, platinum-coated asbestos, rare earth metals, or by using uranium or nickel additives.

Usage

Liquid hydrogen can be used as a form of fuel storage for internal combustion engines and fuel cells. Various submarines (projects 212A and 214, Germany) and hydrogen transport concepts have been created using this aggregate form of hydrogen (see for example "DeepC" or "BMW H2R"). Due to the proximity of the structures, the creators of the equipment at the "ZhV" can use or only modify the systems using liquefied natural gas ("LNG"). However, due to the lower volumetric energy density, combustion requires a higher volume of hydrogen than natural gas. If liquid hydrogen is used instead of "CNG" in reciprocating engines, a more cumbersome fuel system is usually required. With direct injection, the increased intake losses reduce the cylinder filling.

Liquid hydrogen is also used to cool neutrons in neutron scattering experiments. The masses of the neutron and the hydrogen nucleus are practically equal; therefore, the energy exchange in an elastic collision is most effective.

Advantages

The advantage of using hydrogen is the "zero emission" of its use. The product of its interaction with air is water.

Obstacles

One liter of "ZhV" weighs only 0.07 kg. That is, its specific gravity is 70.99 g / l at 20 K. Liquid hydrogen requires cryogenic storage technology, such as special thermally insulated containers, and requires special handling, which is typical for all cryogenic materials. It is close in this respect to liquid oxygen, but requires more caution due to the fire hazard. Even with thermally insulated containers, it is difficult to keep it at the low temperature required to keep it liquid (it usually evaporates at a rate of 1% per day). When handling it, you must also follow the usual safety precautions when working with hydrogen - it is cold enough to liquefy air, which is explosive.

Rocket fuel

Liquid hydrogen is a common component of rocket fuels that is used for jet acceleration of launch vehicles and spacecraft. In most hydrogen-fueled liquid propellant rocket engines, it is first used to regeneratively cool the nozzle and other parts of the engine, before mixing it with an oxidizer and burning it to produce thrust. Used modern H 2 / O 2 engines consume a re-enriched fuel mixture, which results in some unburned hydrogen in the exhaust. In addition to increasing the specific impulse of the engine by reducing the molecular weight, it further reduces the erosion of the nozzle and combustion chamber.

Such obstacles to the use of "LH" in other areas, such as cryogenic nature and low density, are also a limiting factor for use in this case. For 2009, there is only one launch vehicle (LV "Delta-4"), which is entirely a hydrogen rocket. Basically, "ZhV" is used either on the upper stages of rockets, or on blocks, which perform a significant part of the work on putting the payload into space in a vacuum. As one of the measures to increase the density of this type of fuel, there are proposals to use slushy hydrogen, that is, the semi-frozen form of "ZhV".

Hydrogen is the lightest and most abundant chemical element. In our time, everyone has heard of him, and in fact, quite recently, he was a great secret even for the best scientists. Agree, this is enough to learn more about the chemical element hydrogen.

Hydrogen: distribution in nature

As we said above, hydrogen is the most abundant element. And not only on Earth, but throughout the entire Universe! The sun is almost half composed of this chemical element, and most stars are based on hydrogen. In interstellar space, hydrogen is also the most abundant element. On Earth, hydrogen is in the form of compounds. It is a part of oil, gases, even living organisms. The World Ocean contains about 11% hydrogen by mass. There is very little of it in the atmosphere, only about 5 ten-thousandths of a percent.

The history of the discovery of hydrogen

Even medieval alchemists guessed the existence of hydrogen. So, Paracelsus in his writings pointed out that under the action of acid and iron, bubbles of "air" are released. But what kind of "air" he could not understand. In those days, scientists thought that in every combustible substance there is some kind of mystical fiery component that supports combustion. This conjecture is called the "phlogiston" theory. Alchemists believed, for example, that wood was composed of ash, which remains after burning, and phlogiston, which is released when burned.
The properties of hydrogen were first studied by English chemists Henry Cavendish and Joseph Priestley in the 18th century. But they did not fully grasp the essence of their discovery. They thought that a light gas (and hydrogen is 14 times lighter than air) is nothing more than a mystical phlogiston.
And only Antoine Lavoisier proved that hydrogen is not phlogiston at all, but a real chemical element. During his experiments, he managed to get hydrogen from water and then proved that water is obtained back by burning hydrogen. Therefore, this chemical element has received such a name - "giving birth to water".

Chemical properties of hydrogen

Hydrogen is the very first chemical element, in the periodic table it is indicated by the symbol H. It is a light, odorless and colorless gas. Solid hydrogen is the lightest solid, and liquid hydrogen is the lightest liquid. In addition, liquid hydrogen can cause severe frostbite if it comes into contact with the skin. The atoms and molecules of hydrogen are the smallest. Therefore, a balloon inflated with this gas deflates very quickly - hydrogen seeps through the rubber. When hydrogen is mixed with oxygen in the air, a highly explosive mixture is formed. It's called "oxyhydrogen gas".
When the gas is inhaled, the frequency of the voice becomes much higher than normal. For example, a masculine rough bass will sound like Chip and Dale's voices. However, similar chemical experiments it is not worth it, for the reason indicated above. Hydrogen and oxygen form an explosive gas, which can easily explode when exhaled!

Application of hydrogen

Despite its flammability, hydrogen is widely used in many industries. It is mainly used in the production of ammonia for mineral fertilizers and in the production of alcohol and plastics. Once airships and balloons were filled with hydrogen, this light gas lifted them into the air without difficulty. But now in aviation and space technology it is only used as fuel for space rockets. Hydrogen-fueled engines for automobiles have been created. They are the most environmentally friendly, because only water is released during combustion. However on this moment hydrogen engines have a number of significant drawbacks, I do not fully meet the safety requirements, so their use is still completely negligible. V Food Industry hydrogen is used in the production of margarine, as well as for packaging products. It is even registered as a food additive E949. In the power industry, hydrogen is used to cool generators and to generate electricity in hydrogen-oxygen fuel cells.

In the periodic table, it has its definite place of position, which reflects the properties manifested by it and speaks of its electronic structure. However, there is one special atom among all, which occupies two cells at once. It is located in two groups of elements that are completely opposite in terms of the manifested properties. This is hydrogen. These features make it unique.

Hydrogen is not just an element, but also a simple substance, as well as a component of many complex compounds, a biogenic and organogenic element. Therefore, we will consider its characteristics and properties in more detail.

Hydrogen as a chemical element

Hydrogen is an element of the first group of the main subgroup, as well as the seventh group of the main subgroup in the first small period. This period consists of only two atoms: helium and the element we are considering. Let us describe the main features of the position of hydrogen in the periodic table.

1. The ordinal number of hydrogen is 1, the number of electrons is the same, respectively, the number of protons is the same. The atomic mass is 1.00795. There are three isotopes of this element with mass numbers 1, 2, 3. However, the properties of each of them are very different, since an increase in mass even by one for hydrogen is immediately double.
2. The fact that it contains only one electron on the outside allows it to successfully exhibit both oxidizing and reducing properties. In addition, after the donation of an electron, it has a free orbital, which takes part in the formation of chemical bonds by the donor-acceptor mechanism.
3. Hydrogen is a powerful reducing agent. Therefore, its main place is considered the first group of the main subgroup, where it is headed by the most active metals - alkali.
4. However, when interacting with strong reducing agents, such as, for example, metals, it can also be an oxidizing agent, accepting an electron. These compounds are called hydrides. On this basis, he heads the subgroup of halogens, with which he is similar.
5. Due to its very small atomic mass, hydrogen is considered the lightest element. In addition, its density is also very low, so it is also the benchmark for lightness.

Thus, it is obvious that the hydrogen atom is completely unique, unlike all other elements. Consequently, its properties are also special, and the simple and complex substances formed are very important. Let's consider them further.

Simple substance

If we talk about this element as a molecule, then it must be said that it is diatomic. That is, hydrogen (a simple substance) is a gas. Its empirical formula will be written as H 2, and its graphical formula - through a single sigma-relationship H-H. The mechanism of bond formation between atoms is covalent non-polar.

1. Steam conversion of methane.
2. Coal gasification - the process involves heating coal to 1000 0 C, resulting in the formation of hydrogen and high-carbon coal.
3. Electrolysis. This method can be used only for aqueous solutions of various salts, since the melts do not lead to the discharge of water at the cathode.

Laboratory methods for producing hydrogen:

1. Hydrolysis of metal hydrides.
2. The action of dilute acids on active metals and medium activity.
3. Interaction of alkali and alkaline earth metals with water.

To collect the generated hydrogen, the tube must be held upside down. After all, this gas cannot be collected as, for example, carbon dioxide... This is hydrogen, it is much lighter than air. Evaporates quickly, and explodes in large quantities when mixed with air. Therefore, the tube should be inverted. After filling it, it must be closed with a rubber stopper.

To check the purity of the collected hydrogen, you should bring a lighted match to the neck. If the cotton is dull and quiet, then the gas is clean, with minimal air impurities. If it is loud and whistling, it is dirty, with a large proportion of extraneous components.

Areas of use

When hydrogen burns, so much energy (heat) is released that this gas is considered the most profitable fuel... Moreover, it is environmentally friendly. However, to date, its application in this area is limited. This is due to the ill-conceived and unsolved problems of the synthesis of pure hydrogen, which would be suitable for use as fuel in reactors, engines and portable devices, as well as heating boilers residential buildings.

After all, the methods of obtaining this gas are quite expensive, therefore, first it is necessary to develop a special synthesis method. One that will allow you to get a product in large quantities and at minimal cost.

There are several main areas in which the gas we are considering finds application.

1. Chemical syntheses. Hydrogenation produces soaps, margarines, and plastics. With the participation of hydrogen, methanol and ammonia, as well as other compounds, are synthesized.
2. In the food industry - as an additive E949.
3. Aviation industry (rocketry, aircraft construction).
4. Power engineering.
5. Meteorology.
6. Environmentally friendly fuel.

Obviously, hydrogen is just as important as it is in nature. An even greater role is played by the various compounds formed by it.

Hydrogen compounds

These are complex substances containing hydrogen atoms. There are several main types of such substances.

1. Hydrogen halides. The general formula is HHal. Of particular importance among them is hydrogen chloride. It is a gas that dissolves in water to form a hydrochloric acid solution. This acid is widely used in almost all chemical syntheses. And both organic and inorganic. Hydrogen chloride is a compound with the empirical formula HCL and is one of the largest in terms of production in our country every year. Hydrogen halides also include hydrogen iodide, hydrogen fluoride and hydrogen bromide. They all form the corresponding acids.
2. Volatile Almost all of them are quite poisonous gases. For example, hydrogen sulfide, methane, silane, phosphine and others. Moreover, it is very flammable.
3. Hydrides are compounds with metals. They belong to the class of salts.
4. Hydroxides: bases, acids and amphoteric compounds. They necessarily include hydrogen atoms, one or more. Example: NaOH, K 2, H 2 SO 4 and others.
5. Hydrogen hydroxide. This compound is better known as water. Another name for hydrogen oxide. The empirical formula looks like this - H 2 O.
6. Hydrogen peroxide. It is the strongest oxidizing agent, the formula of which is Н 2 О 2.
7. Numerous organic compounds: hydrocarbons, proteins, fats, lipids, vitamins, hormones, essential oils and others.

It is obvious that the variety of compounds of the element we are considering is very great. This once again confirms its high importance for nature and man, as well as for all living beings.

is the best solvent

As mentioned above, the common name for this substance is water. Consists of two hydrogen and one oxygen atoms connected by covalent polar bonds... The water molecule is a dipole, which explains many of its properties. In particular, it is a universal solvent.

Exactly at aquatic environment almost everything happens chemical processes... Internal reactions of plastic and energy metabolism in living organisms are also carried out with the help of hydrogen oxide.

Water is considered to be the most essential substance on the planet. It is known that no living organism can live without it. On Earth, it is able to exist in three states of aggregation:

• liquid;
• gas (steam);
• solid (ice).

There are three types of water depending on the hydrogen isotope that is part of the molecule.

1. Lightweight or protium. An isotope with a mass number of 1. Formula - H 2 O. This is a common form used by all organisms.
2. Deuterium or heavy, its formula is D 2 O. Contains the isotope 2 H.
3. Super heavy or tritium. The formula looks like T 3 O, the isotope is 3 N.

The reserves of fresh protium water on the planet are very important. Already now in many countries there is a lack of it. Methods are being developed for the treatment of salt water in order to obtain drinking water.

Hydrogen peroxide is a versatile remedy

This compound, as mentioned above, is an excellent oxidizing agent. However, with strong representatives it can behave as a restorer too. In addition, it has a pronounced bactericidal effect.

Another name for this compound is peroxide. It is in this form that it is used in medicine. A 3% solution of crystalline hydrate of the compound in question is a medical medicine that is used to treat small wounds in order to disinfect them. However, it has been proven that in this case, wound healing increases over time.

Hydrogen peroxide is also used in rocket fuel, in industry for disinfection and bleaching, as a foaming agent to obtain appropriate materials (foam, for example). In addition, peroxide helps clean aquariums, bleach hair, and whiten teeth. However, at the same time it damages the tissues, so it is not recommended by specialists for these purposes.