Oxygen is ... The oxygen formula. Oxygen molecule

Among all the substances on Earth, a special place is occupied by what life provides-oxygen gas. It is his presence that makes our planet unique among all others, special. Thanks to this substance in the world there are so many beautiful creatures: plants, animals, people. Oxygen is an absolutely irreplaceable, unique and extremely important compound. Therefore, try to find out what it is, what characteristics it has.

Chemical element oxygen: characteristic

To begin with, we characterize the location of this element in the periodic table. This can be done by several items.

1. The serial number is 8.
2. The atomic mass is 15.99903.
3. It is located in the sixth group of the main subgroup of the second period of the system.
4. The charge of the nucleus is +8, the number of protons is 8, the number of electrons is 8, and the number of neutrons is 8. Thus, a double magic number is obtained, so that the stability of the main isotopic form of ¹⁶ O is observed.
5. The Latin name of the element is oxygen. Russian - oxygen, this name is formed from the phrase "giving birth to acids." There is also a synonym, sometimes it is called an oxygen.

Special attention should be paid to the analysis of the electronic structure of the atom, since it explains the stability of the molecule and the physical and chemical properties exhibited.

The structure of the molecule

The electronic configuration of the atom is represented by the formula 1s ² 2s ² 2p ⁴ . From this record it is obvious that before the completion of the energy level and the creation of the covenant octet, oxygen lacks two electrons. This explains its following characteristics:

• The oxygen molecule is diatomic;
• The degree of oxidation of the element is always -2 (except peroxides and fluorine oxide, in which it changes by -1 and +2, respectively);
• Is the strongest oxidant;
• Easy to react even under normal conditions;
• Is capable of forming explosive compounds.

Now consider the question of the structure. How is an oxygen molecule formed? First, the mechanism of formation is covalent nonpolar, that is, due to the socialization of the electrons of each atom. Thus, the bond is also covalent nonpolar. In this case, it is double, since each of the atoms has two unpaired electrons at the outer level. You can very simply picture what oxygen looks like. The formula is as follows: O ₂ or O = O.

Due to the presence of such a bond, the molecule is very stable. For many reactions involving her, special conditions are required: increased pressure, heating, the use of catalysts.

As a chemical element, oxygen is an atom that has three naturally stable isotopes. Their mass numbers are 16, 17, 18, respectively. However, the percentage ratio is very different, since ¹⁶ О 99,759%, and the rest is less than 0,5%. Therefore, the most common and stable isotope is precisely with a mass number of 16.

Simple oxygen substance

If we talk about this element as a simple connection, then immediately it is necessary to designate an aggregate state under ordinary conditions. Oxygen is a gas that has neither taste, color, nor smell. A diatomic molecule, which is the most abundant substance on the planet, after hydrogen and a noble gas of helium.

There are other aggregate states of this substance. Thus, at a negative temperature of -183 ^° C, oxygen condenses into a beautiful blue liquid. If the threshold is exceeded at -200 ⁰ C, the liquid will outgrow into bright blue crystals of a monoclinic needle-like shape.

There are three main types of existence of oxygen in the solid state.

1. Alpha form (α-O ₂ ). It exists at a temperature below 200 ⁰ С.
2. Beta form (β-O ₂ ). The temperature interval is -200-400 ^° C.
3. Gamma form (γ-O ₂ ). The interval from -400 to -500 ⁰ C.

Oxygen is one of the most important and significant gases. Not only for the life of living beings on the planet, but for nature as a whole. It is difficult to name a natural mineral or compound, in which it would not be included as an element.

History of the discovery

The first mention of the fact that in the air there is some gas that supports combustion processes, appeared in the VIII century. However, then to study it, to prove existence and to open it was not a technical possibility. Only after nearly a millennium, in the 18th century this was done, thanks to the work of several scientists.

1. 1771 Karl Scheele experimentally established the air composition and found out that the main two gases are oxygen and nitrogen.
2. Pierre Bayen conducts experiments on the decomposition of mercury and its oxide and officially records the results.
3. 1773 Sheele officially opens the element of oxygen, but does not receive it in its pure form.
4. 1774 Priestley, regardless of Scheele, does the same as he does, and gets pure oxygen by decomposing the mercury oxide.
5. 1775 Antoine Lavoisier gives the name to this element and creates a combustion theory that has existed for more than one hundred years.
6. 1898 Thompson makes the society think that the oxygen of the air can end because of the large emissions of carbon dioxide into the atmosphere.
7. In the same year Timiryazev proves the opposite, because he explains that the supplier of oxygen is the green plants of the planet.

Thus, it became known what oxygen is, what an important and meaningful gas it is. After all the physical and chemical properties of the substance were studied, the methods of its preparation were considered, the approximate content in water, earth crust, atmosphere and other places of the planet was calculated.

Physical properties

We give the main physical parameters by which the compound in question can be characterized.

1. Oxygen is a gas under ordinary conditions, being an integral part of the air (21%). It has no color, taste and smell. Lighter than air, poorly soluble in water.
2. Actively absorbed by coal and metal powders, soluble in organic substances.
3. The boiling point is -183 ^° C.
4. Melting: -218.35 ^° C.
5. The density is 0.0014 g / cm ³ .
6. The crystal lattice is molecular.

Oxygen has paramagnetic properties in the liquid state.

Chemical properties

About how active the gas in question, how it behaves in reactions with other substances, is told in detail by chemistry. Oxygen is able to exhibit several degrees of oxidation, although the most frequent is -2, which is considered to be constant. In addition, there are compounds in which the values are as follows:

• -1;
• -0.5;
• -1/3;
• +0.5;
• +1;
• +2.

The chemical activity is explained by the high affinity for the electron, since the value of electronegativity according to Polling is 3.44. Higher only in fluoride (4). Therefore, oxygen is a very strong oxidant. At the same time, in reactions with even more powerful oxidants behaves as a reducing agent, exhibiting a positive oxidation state. For example, in fluoride oxide O ⁺² F ₂ ^- .

There is a huge number of compounds, which include oxygen. These are the classes of substances, such as:

• Oxides;
• Peroxides;
• Ozonides;
• Superperoxides;
• Acids;
• Bases;
• Salts;
• Organic molecules.

With all elements, oxygen is able to react under normal conditions, except for noble metals, helium, neon and argon and halogens. With inert gases, it does not interact under any conditions.

Obtaining in industry

The oxygen content in air and water is so great (21 and 88%, respectively), that the main industrial method of its synthesis is fractional distillation of liquid air and electrolysis of water.

The first method is especially often used. After all, a lot of this gas can be isolated from the air. However, it will not be completely clean. If a product of a higher quality is required, then electrolysis processes are started up. The raw material for this is either water or alkali. Sodium or potassium hydroxide is used to increase the electrical conductivity of the solution. In general, the essence of the process is reduced to the decomposition of water.

Getting in the lab

Among the laboratory methods, the method of heat treatment has become widespread:

• Peroxides;
• Salts of oxygen-containing acids.

At high temperatures they decompose with the liberation of gaseous oxygen. The process is most often catalyzed by manganese oxide (IV). The oxygen is collected by displacement of water, and it is found out - by a smoldering lobe. As you know, in an oxygen atmosphere, the flame flares very brightly.

Another substance used to produce oxygen in school chemistry lessons is hydrogen peroxide. Even 3% solution under the influence of the catalyst instantly decomposes with the release of pure gas. It only needs to be collected. The catalyst is the same - manganese oxide MnO ₂ .

Among the salts most often used are:

• Bertholets salt, or potassium chlorate;
• Potassium permanganate, or manganese.

To describe the process, we can give an equation. Oxygen is sufficient for laboratory and research needs:

2KClO ₃ = 2KCl + 3O ₂ ↑.

Allotropic modifications of oxygen

There is one allotropic modification that oxygen has. The formula for this compound is O ₃ , it is called ozone. It is a gas that is formed in natural conditions under the influence of ultraviolet and lightning discharges on the oxygen of the air. Unlike O _{2 itself} , ozone has a pleasant smell of freshness, which is felt in the air after the rain with lightning and thunder.

The difference between oxygen and ozone is not only the number of atoms in the molecule, but also in the structure of the crystal lattice. Chemically, ozone is an even stronger oxidizer.

Oxygen is a component of air

The distribution of oxygen in nature is very wide. Oxygen is found in:

• Rocks and minerals;
• Water salty and fresh;
• Soil;
• Plant and animal organisms;
• Air, including the upper atmosphere.

Obviously, it is occupied by all the Earth's shells - the lithosphere, the hydrosphere, the atmosphere and the biosphere. Particularly important is its content in the air. After all, it is this factor that allows life forms, including man, to exist on our planet.

The composition of the air we breathe is extremely heterogeneous. It includes both constant components and variables. The unchanged and always present are:

• carbon dioxide;
• oxygen;
• nitrogen;
• Noble gases.

Variables include water vapor, dust particles, extraneous gases (exhaust, combustion products, rotting, etc.), plant pollen, bacteria, fungi and others.

The importance of oxygen in nature

It is very important how much oxygen is contained in nature. It is known that on some satellites of large planets (Jupiter, Saturn) trace amounts of this gas were discovered, but there is no obvious life there. Our Earth has a sufficient amount of it, which, in combination with water, makes it possible for all living organisms to exist.

In addition to being an active participant in breathing, oxygen still conducts countless oxidation reactions, which release energy for life.

The main suppliers of this unique gas in nature are green plants and some types of bacteria. Thanks to them, a constant balance of oxygen and carbon dioxide is maintained. In addition, ozone builds a protective shield over the entire Earth, which does not allow penetration of a large amount of ultraviolet radiation that destroys it.

Only some types of anaerobic organisms (bacteria, fungi) are able to live outside the oxygen atmosphere. However, there are far fewer of them than those who really need it.

Use of oxygen and ozone in industry

The main areas of use of allotropic oxygen modifications in industry are as follows.

1. Metallurgy (for welding and cutting metals).
2. Medicine.
3. Agriculture.
4. As a rocket fuel.
5. Synthesis of many chemical compounds, including explosives.
6. Purification and disinfection of water.

It is difficult to name even one process in which this great gas, a unique substance - oxygen does not take part.