A chemical element with atomic number seven is indicated by the symbol N (Nitrogenium). Its name - “zot” - from ancient Greek is translated as “lifeless”. This term, according to one of the theories of its occurrence, was proposed by Antoine Lavoisier in 1787, instead of the previous ones “phlogistic”, “spoiled” and “mephitic” air. It was then that a group of French scientists, in whose work Lavoisier took an active part, was developing the principles of chemical nomenclature. Even then, the property of nitrogen to not support either combustion or respiration was noticed.
According to another version, the word "nitrogen" was not invented by Lavoisier with colleagues. It was found in alchemical literature at the dawn of the Middle Ages to refer to the so-called "primary matter of metals", and it was attributed to it, no less, but the property of "alpha and omega" of all that exists.
In nature, nitrogen can be contained as a simple substance with the formula N2, it is a fairly inert gas without taste, color and smell. Three quarters of the Earth’s atmosphere is made up of nitrogen. This element plays a very important role in the existence of plants and animals. In the composition of proteins, its percentage is 16-18% by weight. It is also included in the structure of nucleic acids, nucleoproteins, amino acids, chlorophyll, hemoglobin. In living cells, nitrogen occupies about 2% in the number of atoms, and in terms of mass fraction, this indicator increases to 2.5%. Element N takes fourth place in importance after the main elements of organic chemistry - hydrogen, carbon and oxygen.
Basically, the nitrogen cycle in nature is based on chemical reactions in the air. Among them, oxidation dominates. Also, a significant proportion of nitrogen interactions is occupied by chemical reactions in the biosphere. The main place of N2 in nature is the atmosphere. And plants play an important role, in fact, they begin the nitrogen cycle in nature. The plant world of our planet performs the function of protein synthesis. As materials, nitrates are used that are in the soil. The source of natural nitrates is atmospheric nitrogen and ammonium salts. The mechanism of conversion of a simple substance into a form available for assimilation by plants is called nitrogen binding.
There are two mechanisms for the binding of nitrogen. In the first embodiment, during the lightning discharges, a certain amount of nitrogen oxides is formed. Diluting in water, they provoke the appearance of nitric acid, which gives impetus to the appearance of nitrates in the soil. In the second embodiment, ammonia forms. It is processed by bacteria into nitrates, usually they are located in the nodules of the roots of tuberous plants. This mechanism is also called nitrification.
The death of a plant leads to the formation of ammonium compounds. Bacteria work on them, turning them into nitrates and nitrogen, which returns to the atmosphere. Nitrogen fixation, nitrification, and denitrification are components of a complex mechanism that performs the nitrogen cycle in nature. The scheme of this process is that there is an exchange between nitrogen fixation and its denitrification.
Nitrogen fixation occurs when plants absorb nitrogen compounds from the air, many bacteria and cyanobacteria are involved in this process. Nitrogen fixation products are ammonia, nitrates or nitrites.
The nitrogen cycle in nature with the transition to nitrification takes the next step from fixation. Now ammonia is converted to nitrates and nitrites. During denitrification, the nitrogen cycle in nature ends, with nitrates decomposing to nitrogen. Pseudomonas, rod-shaped bacteria and other microorganisms take an active part in the process.
During denitrification, several intermediates may appear. The most important of these is nitrous oxide, a persistent greenhouse gas.
Opening the topic, it is worth understanding the meaning of the concepts of assimilation and mineralization. Assimilation is the process of the transition of inorganic nitrogen to its organic form. Mineralization refers to the conversion of organic nitrogen to inorganic compounds. Antagonists assimilation and mineralization are an important form of transformation of substances during which the nitrogen cycle in nature occurs.
The presentation of the report on this topic is most successfully carried out using tables and diagrams.