Hydrogen H is a chemical element, one of the most common in our universe. The mass of hydrogen as an element in the composition of substances is 75% of the total content of atoms of another type. It is included in the most important and vital connection on the planet - water. A distinctive feature of hydrogen is also that it is the first element in the periodic system of chemical elements of D. I. Mendeleev.
Discovery and exploration
The first references to hydrogen in the writings of Paracelsus date back to the sixteenth century. But its isolation from the gas mixture of air and the study of combustible properties were already made in the seventeenth century by the scientist Lemery. Hydrogen was thoroughly studied by the English chemist, physicist and naturalist Henry Cavendish, who experimentally proved that the mass of hydrogen is the smallest in comparison with other gases. In the subsequent stages of the development of science, many scientists worked with him, in particular Lavoisier, who called him "giving birth to water."
Characteristic according to the position in the PSHE
Element that opensperiodic table of D. I. Mendeleev, is hydrogen. The physical and chemical properties of the atom show some duality, since the hydrogen is simultaneously assigned to the first group, the main subgroup, if it behaves like a metal and gives up a single electron in the process of a chemical reaction, and to the seventh - in the case of complete filling of the valence shell, that is, reception negative particle, which characterizes it as similar to halogens.
Features of the electronic structure of the element
The properties of the hydrogen atom, the complex substances it is part of, and the simplest substance H2 are primarily determined by the electron configuration of the hydrogen. The particle has one electron with Z=(-1), which rotates in its orbit around the nucleus, containing one proton with unit mass and positive charge (+1). Its electronic configuration is written as 1s1, which means the presence of one negative particle in the very first and only s-orbital for the hydrogen.
When an electron is detached or given away, and an atom of this element has such a property that it is related to metals, a cation is obtained. In fact, the hydrogen ion is a positive elementary particle. Therefore, a hydrogen devoid of an electron is simply called a proton.
Physical properties
If we briefly describe the physical properties of hydrogen, then it is a colorless, slightly soluble gas with a relative atomic mass equal to 2, 14.5 times lighter than air, with a temperatureliquefaction of -252.8 degrees Celsius.
You can easily see from experience that H2 is the easiest. To do this, it is enough to fill three balls with various substances - hydrogen, carbon dioxide, ordinary air - and simultaneously release them from your hand. The one filled with CO2 will reach the ground faster than anyone else, after it the inflated air mixture will descend, and the one containing H2 will rise to the ceiling.
The small mass and size of hydrogen particles justify its ability to penetrate through various substances. On the example of the same ball, this is easy to verify, in a couple of days it will deflate itself, since the gas will simply pass through the rubber. Also, hydrogen can accumulate in the structure of some metals (palladium or platinum), and evaporate from it when the temperature rises.
The low solubility property of hydrogen is used in laboratory practice for its isolation by the method of water displacement. The physical properties of hydrogen (the table below contains the main parameters) determine the scope of its application and methods of production.
| Parameter of an atom or molecule of a simple substance | Meaning |
| Atomic mass (molar mass) | 1.008 g/mol |
| Electronic configuration | 1s1 |
| Crystal lattice | Hexagonal |
| Thermal conductivity | (300 K) 0.1815 W/(m K) |
| Density at n. y. | 0, 08987 g/l |
| Boiling point | -252, 76 °C |
| Specific calorific value | 120, 9 106 J/kg |
| Melting point | -259, 2 °C |
| Water solubility | 18, 8ml/l |
Isotopic composition
Like many other representatives of the periodic system of chemical elements, hydrogen has several natural isotopes, that is, atoms with the same number of protons in the nucleus, but a different number of neutrons - particles with zero charge and unit mass. Examples of atoms that have this property are oxygen, carbon, chlorine, bromine and others, including radioactive ones.
Physical properties of hydrogen 1H, the most common of the representatives of this group, differ significantly from the same characteristics of its counterparts. In particular, the characteristics of the substances in which they are included differ. So, there is ordinary and deuterated water, containing in its composition instead of a hydrogen atom with a single proton, deuterium 2H - its isotope with two elementary particles: positive and uncharged. This isotope is twice as heavy as ordinary hydrogen, which explains the fundamental difference in the properties of the compounds they make up. In nature, deuterium is 3200 times rarer than hydrogen. The third representative is tritium 3Н, in the nucleus it has two neutrons and one proton.
Methods of obtaining and selecting
Laboratory and industrial methods for producing hydrogen are very different. Yes, in small quantitiesgas is produced primarily through reactions involving minerals, while large-scale production uses organic synthesis to a greater extent.
The following chemical interactions are used in the laboratory:
- The reaction of alkali and alkaline earth metals with water to form alkali and the desired gas.
- Electrolysis of an aqueous electrolyte solution, H2↑ is released at the anode, and oxygen is released at the cathode.
- Decomposition of alkali metal hydrides with water, the products are alkali and, accordingly, gas H2↑.
- Reaction of dilute acids with metals to form s alts and H2↑.
- The action of alkalis on silicon, aluminum and zinc also promotes the release of hydrogen in parallel with the formation of complex s alts.
In industrial interests, gas is obtained by methods such as:
- Thermal decomposition of methane in the presence of a catalyst to its constituent simple substances (350 degrees reaches the value of such an indicator as temperature) - hydrogen H2↑ and carbon C.
- Passing vaporous water through coke at 1000 degrees Celsius to form carbon dioxide CO2 and H2↑ (the most common method).
- Conversion of gaseous methane on a nickel catalyst at temperatures reaching 800 degrees.
- Hydrogen is a byproduct of the electrolysis of aqueous solutions of potassium or sodium chlorides.
Chemicalinteractions: generalities
The physical properties of hydrogen largely explain its behavior in reaction processes with one or another compound. The valency of the hydrogen is 1, since it is located in the first group in the periodic table, and the degree of oxidation shows a different one. In all compounds, except for hydrides, hydrogen in s.o.=(1+), in molecules like ХН, ХН2, ХН3 – (1-).
A hydrogen gas molecule, formed by creating a generalized electron pair, consists of two atoms and is quite stable energetically, which is why under normal conditions it is somewhat inert and enters into reactions when normal conditions change. Depending on the degree of oxidation of hydrogen in the composition of other substances, it can act both as an oxidizing agent and a reducing agent.
Substances with which it reacts and forms hydrogen
Elemental interactions to form complex substances (often at elevated temperatures):
- Alkaline and alkaline earth metal + hydrogen=hydride.
- Halogen + H2=hydrogen halide.
- Sulfur + hydrogen=hydrogen sulfide.
- Oxygen + H2=water.
- Carbon + hydrogen=methane.
- Nitrogen + H2=ammonia.
Interaction with complex substances:
- Producing synthesis gas from carbon monoxide and hydrogen.
- Recovery of metals from their oxides using H2.
- Hydrogen saturation of unsaturated aliphatichydrocarbons.
Hydrogen bond
The physical properties of hydrogen are such that they allow it, being in combination with an electronegative element, to form a special type of bond with the same atom from neighboring molecules that have unshared electron pairs (for example, oxygen, nitrogen and fluorine). The clearest example on which it is better to consider such a phenomenon is water. It can be said that it is stitched with hydrogen bonds, which are weaker than covalent or ionic ones, but due to the fact that there are many of them, they have a significant effect on the properties of the substance. Essentially, hydrogen bonding is an electrostatic interaction that binds water molecules into dimers and polymers, giving rise to its high boiling point.
Hydrogen in mineral compounds
The composition of all inorganic acids includes a proton - a cation of such an atom as hydrogen. A substance whose acid residue has an oxidation state greater than (-1) is called a polybasic compound. It contains several hydrogen atoms, which makes dissociation in aqueous solutions multi-stage. Each subsequent proton breaks away from the rest of the acid more and more difficult. According to the quantitative content of hydrogens in the medium, its acidity is determined.
Hydrogen also contains hydroxyl groups of bases. In them, hydrogen is connected to an oxygen atom, as a result, the oxidation state of this alkali residue is always equal to (-1). The content of hydroxyls in the medium determines its basicity.
Application in human activities
Cylinders with a substance, as well as containers with other liquefied gases, such as oxygen, have a specific appearance. They are painted dark green with a bright red "Hydrogen" lettering. Gas is pumped into a cylinder under a pressure of about 150 atmospheres. The physical properties of hydrogen, in particular the lightness of the gaseous state of aggregation, are used to fill it in a mixture with helium balloons, balloons, etc.
Hydrogen, the physical and chemical properties of which people learned to use many years ago, is currently used in many industries. Most of it goes to the production of ammonia. Hydrogen is also involved in the production of metals (hafnium, germanium, gallium, silicon, molybdenum, tungsten, zirconium, and others) from oxides, acting in the reaction as a reducing agent, hydrocyanic and hydrochloric acids, methyl alcohol, and artificial liquid fuel. The food industry uses it to turn vegetable oils into solid fats.
Determined the chemical properties and use of hydrogen in various processes of hydrogenation and hydrogenation of fats, coals, hydrocarbons, oils and fuel oil. It is used to produce precious stones, incandescent lamps, forging and welding of metal products under the influence of an oxygen-hydrogen flame.
