Hydrogen is that matter? Chemical and physical properties of hydrogen

Every chemical element in the periodic systemIt has its own specific position, which reflects the properties it exhibits and speaks of its electronic structure. However, among all there is one special atom that occupies two cells at once. It is located in two groups of elements that are completely opposite in the properties shown. This is hydrogen. Such features make it unique.

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

Hydrogen as a chemical element

Hydrogen is an element of the first group of the mainsubgroups, 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 under consideration. We describe the main features of the position of hydrogen in the periodic system.

1. The sequence number of hydrogen is 1, the numberelectrons is the same, respectively, the same protons. 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 the increase in mass even by one for hydrogen is immediately double.
2. That on the outer energy level hecontains only one electron, allows it to successfully show both oxidizing and reducing properties. In addition, after the recoil of an electron, it remains a free orbital, which takes part in the formation of chemical bonds by the donor-acceptor mechanism.
3. Hydrogen is a strong reducing agent. Therefore, its main place is considered the first group of the main subgroup, where it heads the most active metals - alkaline.
4. However, when interacting with strongreducing agents, such as, for example, metals, it can be an oxidizing agent, taking an electron. These compounds are called hydrides. On this basis, he heads the subgroup of halogens, which is similar.
5. Due to the very small atomic mass, hydrogen is considered the lightest element. In addition, its density is also very small, so it is also the benchmark of lightness.

Thus, it is obvious that a hydrogen atom iscompletely unique, unlike any other element. Consequently, its properties are also special, and the simple and complex substances formed are very important. Consider them further.

Simple substance

If we speak of this element as a molecule, then it must be said that it is diatomic. That is, hydrogen (simple substance) is a gas. His empirical formula will be written as H₂, and graphic - through a single sigma-link HH. The mechanism of bonding between atoms is a covalent non-polar.

Even Henry Cavendish in 1766 managed to openthis substance. It was he who proved that hydrogen is a gas, and one that can explode in air. Later properties were well studied, it became clear that this substance is the lightest known.

Even later, Lavoisier gave the name (as an elementso and the substance based on it) in Latin - hydrogenium, which means "giving birth to water." In 1781, Henry Cavendish, the discoverer of this element, proved that water is a combination of hydrogen and oxygen, that is, it is the product of their interaction. And the fact that light gas is also very flammable, was known in the XVI century, this was reflected in the records of Paracelsus.

So molecular hydrogen is verycommon in nature and naturally occurring gaseous compound consisting of two atoms, which can explode in air. In addition, the molecule can decay into atoms, which take part in nuclear reactions, turning into helium nuclei. These processes occur continuously on the Sun and in space, which are the main suppliers of this compound.

Hydrogen is a substance that is able to manifest itself as both an oxidizing agent and a reducing agent. It also finds a very wide application in human activity.

Physical properties

Physical parameters of hydrogen is as follows:

1. Boiling point - (-252,76 ⁰FROM).
2. Melting point - (-259.2 ⁰FROM).
3. In the indicated temperature range it is a colorless, odorless liquid.
4. At very high pressure, there are snow-like crystals of solid hydrogen.
5. Under certain conditions (high pressure and low temperatures) it is able to pass into the metallic state.
6. Practically insoluble in water, so it is possible to collect the method of water displacement upon receipt in laboratory conditions.
7. Under normal conditions, hydrogen is an odorless, colorless, and tasteless gas.
8. It is flammable and explosive.
9. It dissolves well in metals, as it can diffuse through their thickness.
10. About 14.5 times this gas is lighter than air.

The crystal lattice of a simple substance is molecular, the bonds are weak, and therefore easily destroyed.

Chemical properties

As mentioned above, hydrogen is capableshow both reducing and oxidizing properties. Possible oxidation states of the element +1; -one. Therefore, it is often used in industry for syntheses and various reactions.

Oxidizing properties of hydrogen

1. Interaction with active metals (alkali and alkaline earth metals) under normal conditions leads to the formation of salt-like compounds, called hydrides. For example: LiH, CaH₂, KH, MgH₂ and others.
2. Compounds with low-active metals under the influence of high temperatures or high illumination (photochemical initiation of reactions) also form hydrides.

Hydrogen reduction properties

1. Interaction under normal conditions only with fluorine (as a strong oxidizing agent). As a result, hydrogen fluoride or hydrofluoric acid HF is formed.
2. Interaction with almost all non-metals, but under certain rather tough conditions. Connection examples: H₂S, NH₃, H₂O ph₃SiH₄ and others.
3. Restores metals from their oxides to simple substances. This is one of the industrial methods of producing metals, called hydrogenthermia.

Separately, it is necessary to distinguish the reactions thatused in organic syntheses. They are called hydrogenation - hydrogen saturation and dehydrogenation, that is, its cleavage from the molecule. Based on these conversion methods, a variety of hydrocarbons and other organic compounds are obtained.

Being in nature

Hydrogen is the most common substance onour planet and beyond. After all, almost all interstellar space and stars are composed precisely of this compound. In space, it can exist in the form of:

• plasma;
• gas;
• ions;
• atoms;
• molecules.

There are several types of clouds of different densities, consisting precisely of this substance.

If we talk about the distribution specifically inthe earth's crust, then hydrogen is in second place by the number of atoms after oxygen, about 17%. In the free form is rare, only in small quantities in the composition of dry air. The most common compound of this element is water. It is in its composition that it is found on the planet.

Hydrogen is also an obligatory compound.part of any living organism. Moreover, in the human body the share of this atom accounts for 63%. Hydrogen is an organogenic element, therefore it forms molecules of proteins, fats, carbohydrates and nucleic acids, as well as many other vital compounds.

Receiving

There are different ways to get the gas under consideration. These include several industrial and laboratory synthesis options.

Industrial methods for producing hydrogen:

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

Laboratory methods for producing hydrogen:

1. Hydrolysis of metal hydrides.
2. The effect of diluted acids on active metals and medium activity.
3. The interaction of alkali and alkaline earth metals with water.

To collect the hydrogen produced, it is necessarykeep the tube upside down. After all, this gas can not be collected as, for example, carbon dioxide. This is hydrogen, it is much lighter than air. Rapidly disappears, and in large quantities when mixed with air it explodes. Therefore, the tube should be inverted. After its filling, it must be closed with a rubber stopper.

To check the purity of the collected hydrogen,should bring a lit match to the neck. If the cotton is deaf and quiet, then the gas is clean, with minimal air impurities. If loud and whistling - dirty, with a large proportion of foreign components.

Areas of use

During the combustion of hydrogen is so mucha large amount of energy (heat) that the gas is considered the most profitable fuel. Also environmentally friendly. However, today its use in this area is limited. This is due to the unreasonable 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 of residential buildings.

After all, the methods of obtaining this gas is enoughexpensive, so first it is necessary to develop a special method of synthesis. One that will allow you to get a product in large volume and with minimal cost.

There are several main areas in which the gas under consideration is used.

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

It is obvious that hydrogen is just as important as it is common in nature. Another important 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. This 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 that has an empirical formula HCL and is one of the largest in terms of production in our country annually. Also hydrogen halides include hydrogen iodide, hydrogen fluoride and hydrogen bromide. They all form the corresponding acids.
2. Volatile hydrogen compounds of non-metals. Virtually all of them are quite poisonous gases. For example, hydrogen sulfide, methane, silane, phosphine and others. It is very flammable.
3. Hydrides - compounds with metals. Belong to the class of salts.
4. Hydroxides: bases, acids and amphoteric compounds. Their composition necessarily includes hydrogen atoms, one or more. Example: NaOH, K₂[AL (OH)₄] H₂CO₄ and others.
5. Hydrogen hydroxide. This compound is more commonly known as water. Another name is hydrogen oxide. The empirical formula looks like this - H₂ABOUT.
6. Hydrogen peroxide. It is the strongest oxidizing agent whose formula is H₂ABOUT₂.
7. Numerous organic compounds: hydrocarbons, proteins, fats, lipids, vitamins, hormones, essential oils and other.

It is obvious that the variety of compounds of the element under consideration is very large. This once again confirms its high value for nature and man, as well as for all living beings.

Hydrogen oxide is the best solvent.

Как уже упоминалось выше, простонародное название this substance is water. It consists of two hydrogen atoms and one oxygen, interconnected by covalent polar bonds. A water molecule is a dipole, this explains many of the properties it exhibits. In particular, the fact that it is a universal solvent.

It is in the aquatic environment that almost all chemical processes occur. 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 important substance on the planet. It is known that no living organism can live without it. On Earth, it can exist in three aggregative states:

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

Depending on the isotope of hydrogen, which is part of the molecule, there are three types of water.

1. Easy or protievy. Isotope with mass number 1. Formula - H₂A. It is a habitual form that all organisms use.
2. Deuterium or heavy, its formula is D₂O. Contains isotope ²N.
3. Super heavy or tritium. The formula looks like T₃Oh, isotope - ³N.

Very important reserves of fresh water on the planet. Already in many countries there is a lack of it. Developed ways to handle salt water in order to get drinking.

Hydrogen peroxide is a universal remedy.

This compound, as mentioned above,fine oxidizer. However, with strong representatives can behave as a reducing agent, 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 the crystalline hydrate of the compound in question is a medical medicine that is used for treating small wounds in order to disinfect them. However, it has been proven that with this, the healing of injuries increases over time.

Also, hydrogen peroxide is used in rocketfuel, in industry for disinfection and bleaching, as a foaming agent for the production of appropriate materials (foam, for example). In addition, peroxide helps clean the aquariums, bleach hair and whiten your teeth. However, it damages the tissues, so experts are not recommended for this purpose.