Among the substances on Earth occupies a special place that provides life - oxygen gas.It was his presence makes our planet unique among all others, especially.Due to the substance of the world lives as beautiful creatures: plants, animals, people.Oxygen - it is absolutely irreplaceable, unique and extremely important connection.So we try to find out what it is, what characteristics has.
element oxygen: characterization
to describe the location of the start of the element in the periodic system.This can be done a few points.
- Number - 8.
- atomic mass - 15.99903.
- Located in the sixth group of the main subgroup of the second period.
- charge of the nucleus - eight, the number of protons - 8, electron - 8 neutrons - 8. Thus, a double magic number, so there is stability of the main forms of 16O isotope.
- Latin name of the element - oxygen.Russian - oxygen is name comes from "giving birth to acid."There is also a synonym, sometimes called oxygenic.
Special attention is given the analysis of the electronic structure of the atom, as it is explained by the stability of the molecule and exhibit physical and chemical properties.
structure of the molecule
electronic configuration of atoms represented by formula 1s22s22p4.From this listing it is evident that until the completion of the energy level and the promised creation octet oxygen is missing two electrons.This explains its following characteristics:
- diatomic molecule of oxygen;
- oxidation -2 element always (except peroxides oxide and fluorine, in which it is changed to 1 and 2, respectively);
- is a strong oxidant;
- easily reacts even under normal conditions;
- able to form explosive compounds.
Now consider the question of the structure.As the oxygen molecule is formed?First, the mechanism of formation of a covalent non-polar, that is by sharing of electrons each atom.Thus, the non-polar covalent bond well.However, it is double, since each atom has two unpaired electrons in the outer level.It can be very easy to portray what it looks like oxygen.The formula is: O 2 or O = O.
Due to the presence of such a relationship is very stable molecule.For many reactions involving it requires special conditions: pressurizing, heating, the use of catalysts.
As oxygen is a chemical element - an atom having three stable isotope existing in nature.Their mass numbers are respectively 16, 17, 18. However, the percentage is very different, as the 16 O 99.759%, and the remaining less than 0.5%.Therefore, the most common and stable isotope - that of mass number 16.
simple substance oxygen
If we talk about this element as a simple connection, you should immediately designate the aggregate state under normal conditions.Oxygen - a gas that has no taste, no color, no odor.Diatomic molecule, which is the most abundant substance on the planet, after hydrogen and noble gas helium.
There are also other states of aggregation of the substance.Thus, at temperatures below freezing -1830S oxygen is condensed into a beautiful blue liquid.If you exceed the threshold -2000S, the liquid turn into a bright blue crystals monoclinic needle-shaped.
total there are three main types of the existence of oxygen in the solid state.
- alpha form (α-O2).There is at a temperature below 200 0C.
- Beta-form (β-O2).The temperature range -200-4000S.
- Gamma-form (γ-O2).The interval from -400 to -5000S.
Oxygen - this is one of the most important and significant emissions.Not only for the life of living beings on the planet, but also for nature in general.Hardly a natural mineral or compound, which he had not entered as an element.
History of discovery
first mention of the fact that in the air there is any gas that supports combustion processes, has appeared in the VIII century.But then explore it, to prove the existence and discover there was no technical possibility.Only after almost a millennium, in the XVIII century it was done through the work of several scientists.
- 1771 Carl Scheele empirically established the composition of the air and found that the two main gas - it is oxygen and nitrogen.
- Pierre Bayen conducting experiments on the decomposition of mercury and mercury oxide and officially records the results.
- 1773 Scheele officially opens the element oxygen, but does not get it in pure form.
- 1774 Priestley regardless Scheele doing the same as he was opening, and gets pure oxygen decomposition of mercury oxide.
- 1775 Antoine Lavoisier gives the name of this element and makes the theory of combustion that lasted more than one hundred years.
- 1898 Thompson makes society think about the fact that the oxygen in the air can result because of the large emissions of carbon dioxide into the atmosphere.
- In the same year Timiryazev proves the opposite, as it explains that the oxygen supplier are green plants of the planet.
Thus, it became known that a is oxygen, which is an important and significant for the life of this gas.Once studied all the physical and chemical properties of the substance, considered methods for its preparation, counted approximate content in the water, the earth's crust, atmosphere and other places of the planet.
physical properties
present the basic physical parameters, which can be characterized by the objective compound.
- oxygen - the gas under normal conditions, which is an integral part of the air (21%).It has no color, taste and smell.Lighter than air, is poorly soluble in water.
- actively absorb carbon and metal powders, soluble organic substances.
- boiling point of -1830S.
- Melting -218,350S.
- density of 0.0014 g / cm3.
- Crystalline molecular.
oxygen has paramagnetic properties in the liquid state.
chemical properties
Just how active consideration gas, how it behaves in the reactions with other substances, recounts chemistry.Oxygen is able to exercise some degree of oxidation, although the most common is -2, which is assumed to be constant.In addition it found compounds in which the following values:
- -1;
- -0,5;
- -1/3;
- +0,5;
- +1;
- +2.
chemical activity due to the high electron affinity, since the value of electronegativity on Pauling had 3.44.Only at higher fluoride (4).Therefore, oxygen is a strong oxidizing agent.At the same time, the reactions with more strong oxidants behaves as a reductant, showing a positive oxidation state.For example, a fluorine oxide O 2 + F2-.
There is a huge number of compounds which include oxygen.These are the classes of substances such as:
- oxides;
- peroxides;
- ozonides;
- superoxide;
- acid;
- base;
- salt;
- organic molecules.
with all the elements oxygen can react under normal conditions, except for precious metals, helium, neon and argon and halogen.With inert gases, he does not react under any circumstances.
Preparation industry
oxygen content in the air and water is so large (21 and 88% respectively), the main industrial way of its synthesis is fractional distillation of liquid air and water electrolysis.
most often used the first method.It can be distinguished from the air a lot of gas.However, it is not entirely clear.If the product requires a higher quality, then allowed to stroke electrolysis processes.The raw material for this purpose is either water or alkali.Sodium or potassium hydroxide is used to increase the strength of the electrical conductivity of the solution.In general, the essence of the process is reduced to the decomposition of water.
obtained in the laboratory
Among the laboratory techniques became widespread method of heat treatment:
- peroxides;
- salts of oxygen-containing acids.
At high temperatures, they decompose with release of gaseous oxygen.Catalyze the process often manganese oxide (IV).Collect oxygen displacement of water, and discover - smoldering splinter.As you know, in an atmosphere of oxygen flame flares up brightly.
Another substance used to produce oxygen on school chemistry lessons - hydrogen peroxide.Even a 3% solution under the action of the catalyst instantly decomposes to release the pure gas.It must be a time to gather.The catalyst was the same - a manganese oxide MnO2.
Among salts are most commonly used:
- bertoletova salt or potassium chlorate;
- potassium permanganate or potassium permanganate.
to describe the process, you can bring the equation.Oxygen is released enough for the laboratory and research needs:
2KClO3 = 2KCl + 3O2 ↑.
allotropic modification of oxygen
There is one allotropic modification, which is oxygen.The formula of this compound O3, it is called ozone.This gas, which is produced in nature when exposed to ultraviolet radiation and lightning on oxygen in the air.Unlike most O2, ozone has a pleasant smell of freshness that is felt in the air after the rain with lightning and thunder.
difference of oxygen and ozone is not only the number of atoms in the molecule, but in the structure of the crystal lattice.Chemically, ozone - even more powerful oxidant.
Oxygen - a component of the air with oxygen
Spread in nature very well.Oxygen is found in:
- rocks and minerals;
- salt and fresh water;
- soil;
- plant and animal organisms;
- air, including the upper atmosphere.
Obviously, they are busy all the Earth's shell - the lithosphere, hydrosphere, atmosphere and biosphere.Particularly important is the content in the composition of air.After all, this factor makes it possible to exist on our planet life forms, including humans.
composition of the air we breathe, are extremely heterogeneous.It includes both the constant components and variables.By constant and ever present concern:
- carbon dioxide;
- oxygen;
- nitrogen;
- noble gases.
Variables include water vapor, dust, extraneous gases (exhaust products of combustion, rotting, etc.), plant pollen, bacteria, fungi and other.
value of oxygen in nature
It is very important how much oxygen is in the nature.It is known that some satellites of the major planets (Jupiter, Saturn) were detected trace amounts of gas, but it is clear there is no life.Our Earth has a sufficient amount, which is combined with water makes it possible to exist in all living organisms.
In addition, he is an active member of breathing oxygen still spends countless oxidation reactions that result in released energy for life.
main suppliers of this unique gas in nature are green plants and certain bacteria.Thanks to them, maintained a constant balance of oxygen and carbon dioxide.In addition, ozone builds a protective shield over the entire Earth, which does not allow plenty of destructive ultraviolet radiation.
Only some types of anaerobic organisms (bacteria, fungi) are able to live outside the atmosphere of oxygen.However, they are much less than those who really need it.
use of oxygen and ozone in the industry
main allotropic modifications of the use of oxygen in the industry follows.
- Metallurgy (for welding and cutting metals).
- Medicine.
- Agriculture.
- as rocket fuel.
- synthesis of many chemical compounds, including explosives.
- Cleansing and disinfection of water.
difficult to name at least one process which does not take part of this great gas, a unique ingredient - oxygen.
