Chemical properties of oxygen for living organisms. Oxygen cycle. Biological significance of oxygen. Reserve fund of the oxygen cycle, sources of oxygen supply to the biosphere. Use of oxygen in life

Sea and fresh waters contain a huge amount of bound oxygen - 85.82% (by mass). More than 1,500 compounds in the earth's crust contain oxygen.

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Federal State Budgetary Educational Institution of Higher Professional Education “Mordovian State University named after. N. P. Ogareva"

Medical Institute

Department of Analytical Chemistry

Essay

on the topic of:

"Biological role of oxygen."

Completed:

1st year student

104 specialty groups

"Medicine"

Belyaeva Maria

Checked:

PhD in Chemistry

Gurvich Lyudmila Govseevna

Saransk 2015-2016

Introduction

Oxygen is an element of the 16th group (according to the outdated classification - the main subgroup of group VI), the second period of the periodic table of chemical elements of D.I. Mendeleev, with atomic number 8. It is designated by the symbol O (lat. Oxygenium). Oxygen is a chemically active non-metal and is the lightest element from the group of chalcogens. The simple substance oxygen (CAS number: 7782-44-7) under normal conditions is a colorless, tasteless and odorless gas, the molecule of which consists of two oxygen atoms (formula O2), for which reason it is also called dioxygen. Liquid oxygen is light blue in color, while solid oxygen is light blue crystals.

There are other allotropic forms of oxygen, for example, ozone (CAS number: 10028-15-6) - under normal conditions, a blue gas with a specific odor, the molecule of which consists of three oxygen atoms (formula O3).

History of the discovery of oxygen.

It is officially believed that oxygen was discovered by the English chemist Joseph Priestley on August 1, 1774 by decomposing mercuric oxide in a hermetically sealed vessel (Priestley directed sunlight at this compound using a powerful lens).

2HgO (t) → 2Hg + O 2

However, Priestley initially did not realize that he had discovered a new simple substance; he believed that he had isolated one of the constituent parts of air (and called this gas “dephlogisticated air”). Priestley reported his discovery to the outstanding French chemist Antoine Lavoisier. In 1775, A. Lavoisier established that oxygen is a component of air, acids and is found in many substances.

A few years earlier (in 1771), oxygen was obtained by the Swedish chemist Karl Scheele. He calcined saltpeter with sulfuric acid and then decomposed the resulting nitric oxide. Scheele called this gas “fire air” and described his discovery in a book published in 1777 (precisely because the book was published later than Priestley announced his discovery, the latter is considered the discoverer of oxygen). Scheele also reported his experience to Lavoisier.

An important stage that contributed to the discovery of oxygen was the work of the French chemist Peter Bayen, who published works on the oxidation of mercury and the subsequent decomposition of its oxide.

Finally, A. Lavoisier finally figured out the nature of the resulting gas, using information from Priestley and Scheele. His work was of enormous importance because thanks to it, the phlogiston theory, which was dominant at that time and hampered the development of chemistry, was overthrown. Lavoisier conducted experiments on the combustion of various substances and disproved the theory of phlogiston, publishing results on the weight of the elements burned. The weight of the ash exceeded the original weight of the element, which gave Lavoisier the right to claim that during combustion a chemical reaction (oxidation) of the substance occurs, and therefore the mass of the original substance increases, which refutes the theory of phlogiston.

Thus, the credit for the discovery of oxygen is actually shared between Priestley, Scheele and Lavoisier.

Being in nature

Oxygen is the most common element in the earth's crust, its share (in various compounds, mainlysilicates ) accounts for about 47% of the solid massearth's crust . Sea and fresh waters contain a huge amount of bound oxygen - 85.82% (by mass). More than 1,500 compounds in the earth's crust contain oxygen.

Oxygen is the main biogenic element that is part of the molecules of all the most important substances that provide the structure and function of cells - proteins, nucleic acids, carbohydrates, lipids, as well as many low-molecular compounds. Every plant or animal contains much more oxygen than any other element (on average about 70%). Human muscle tissue contains 16% oxygen, bone tissue - 28.5%; In total, the body of an average person (body weight 70 kg) contains 43 kg of oxygen. Oxygen enters the body of animals and humans mainly through the respiratory organs (free oxygen) and with water (bound oxygen). The body's need for oxygen is determined by the level (intensity) of metabolism, which depends on the mass and surface of the body, age, gender, nature of nutrition, external conditions, etc. In ecology, the ratio of total respiration (that is, total oxidative processes) of a community is determined as an important energy characteristic organisms to its total biomass.

Small amounts of oxygen are used in medicine: oxygen (from so-called oxygen pillows) is given to patients who have difficulty breathing for some time. However, it must be borne in mind that prolonged inhalation of air enriched with oxygen is dangerous to human health. High concentrations of oxygen cause the formation of free radicals in tissues, disrupting the structure and function of biopolymers. Ionizing radiation has a similar effect on the body. Therefore, a decrease in the oxygen content (hypoxia) in tissues and cells when the body is irradiated with ionizing radiation has a protective effect - the so-called oxygen effect. This effect is used in radiation therapy: increasing the oxygen content in the tumor and decreasing its content in the surrounding tissues increases radiation damage to tumor cells and reduces damage to healthy ones. For some diseases, saturation of the body with oxygen under high pressure is used - hyperbaric oxygenation.

Plan:

History of discovery

Origin of name

Being in nature

Receipt

Physical properties

Chemical properties

Application

Biological role of oxygen

Toxic oxygen derivatives

10. Isotopes

Oxygen

Oxygen- element of the 16th group (according to the outdated classification - the main subgroup of group VI), the second period of the periodic system of chemical elements of D.I. Mendeleev, with atomic number 8. Denoted by the symbol O (lat. Oxygenium). Oxygen is a chemically active non-metal and is the lightest element from the group of chalcogens. Simple substance oxygen(CAS number: 7782-44-7) under normal conditions is a colorless, tasteless and odorless gas, the molecule of which consists of two oxygen atoms (formula O 2), and therefore it is also called dioxygen. Liquid oxygen has a light blue color, and solid crystals are light blue in color.

There are other allotropic forms of oxygen, for example, ozone (CAS number: 10028-15-6) - under normal conditions, a blue gas with a specific odor, the molecule of which consists of three oxygen atoms (formula O 3).

1. History of discovery

It is officially believed that oxygen was discovered by the English chemist Joseph Priestley on August 1, 1774 by decomposing mercuric oxide in a hermetically sealed vessel (Priestley directed sunlight at this compound using a powerful lens).

However, Priestley initially did not realize that he had discovered a new simple substance; he believed that he had isolated one of the constituent parts of air (and called this gas “dephlogisticated air”). Priestley reported his discovery to the outstanding French chemist Antoine Lavoisier. In 1775, A. Lavoisier established that oxygen is a component of air, acids and is found in many substances.

A few years earlier (in 1771), oxygen was obtained by the Swedish chemist Karl Scheele. He calcined saltpeter with sulfuric acid and then decomposed the resulting nitric oxide. Scheele called this gas “fire air” and described his discovery in a book published in 1777 (precisely because the book was published later than Priestley announced his discovery, the latter is considered the discoverer of oxygen). Scheele also reported his experience to Lavoisier.

An important step that contributed to the discovery of oxygen was the work of the French chemist Pierre Bayen, who published works on the oxidation of mercury and the subsequent decomposition of its oxide.

Finally, A. Lavoisier finally figured out the nature of the resulting gas, using information from Priestley and Scheele. His work was of enormous importance because thanks to it, the phlogiston theory, which was dominant at that time and hampered the development of chemistry, was overthrown. Lavoisier conducted experiments on the combustion of various substances and disproved the theory of phlogiston, publishing results on the weight of the burned elements. The weight of the ash exceeded the original weight of the element, which gave Lavoisier the right to claim that during combustion a chemical reaction (oxidation) of the substance occurs, and therefore the mass of the original substance increases, which refutes the theory of phlogiston.

Thus, the credit for the discovery of oxygen is actually shared between Priestley, Scheele and Lavoisier.

1. origin of name

The word oxygen (also called “acid solution” at the beginning of the 19th century) owes its appearance in the Russian language to some extent to M.V. Lomonosov, who introduced the word “acid”, along with other neologisms; Thus, the word “oxygen”, in turn, was a tracing of the term “oxygen” (French oxygène), proposed by A. Lavoisier (from ancient Greek ὀξύς - “sour” and γεννάω - “giving birth”), which is translated as “generating acid”, which is associated with its original meaning - “acid”, which previously meant substances called oxides according to modern international nomenclature.

1. Being in nature

Oxygen is the most common element on Earth; its share (in various compounds, mainly silicates) accounts for about 47.4% of the mass of the solid earth's crust. Sea and fresh waters contain a huge amount of bound oxygen - 88.8% (by mass), in the atmosphere the content of free oxygen is 20.95% by volume and 23.12% by mass. More than 1,500 compounds in the earth's crust contain oxygen.

Oxygen is part of many organic substances and is present in all living cells. In terms of the number of atoms in living cells, it is about 25%, and in terms of mass fraction - about 65%.

The discovery of oxygen happened twice, in the second half of the 18th century, several years apart. In 1771, oxygen was obtained by Swede Karl Scheele by heating saltpeter and sulfuric acid. The resulting gas was called "fire air". In 1774, the English chemist Joseph Priestley carried out the process of decomposing mercuric oxide in a completely closed vessel and discovered oxygen, but mistook it for an ingredient in air. Only after Priestley shared his discovery with the Frenchman Antoine Lavoisier did it become clear that a new element (calorizator) had been discovered. Priestley takes the lead in this discovery because Scheele published his scientific work describing the discovery only in 1777.

Oxygen is an element of group XVI of period II of the periodic table of chemical elements by D.I. Mendeleev, has atomic number 8 and atomic mass 15.9994. It is customary to denote oxygen by the symbol ABOUT(from Latin Oxygenium- generating acid). In Russian the name oxygen became a derivative of acids, a term that was introduced by M.V. Lomonosov.

Being in nature

Oxygen is the most common element found in the earth's crust and the World Ocean. Oxygen compounds (mainly silicates) make up at least 47% of the mass of the earth's crust; oxygen is produced during photosynthesis by forests and all green plants, most of which comes from phytoplankton in marine and fresh waters. Oxygen is an essential component of any living cells and is also found in most substances of organic origin.

Physical and chemical properties

Oxygen is a light non-metal, belongs to the group of chalcogens, and has high chemical activity. Oxygen, as a simple substance, is a colorless, odorless and tasteless gas; it has a liquid state - light blue transparent liquid and a solid state - light blue crystals. Consists of two oxygen atoms (denoted by the formula O₂).

Oxygen is involved in redox reactions. Living things breathe oxygen from the air. Oxygen is widely used in medicine. In case of cardiovascular diseases, to improve metabolic processes, oxygen foam (“oxygen cocktail”) is injected into the stomach. Subcutaneous administration of oxygen is used for trophic ulcers, elephantiasis, and gangrene. Artificial ozone enrichment is used to disinfect and deodorize air and purify drinking water.

Oxygen is the basis of the life activity of all living organisms on Earth and is the main biogenic element. It is found in the molecules of all the most important substances that are responsible for the structure and functions of cells (lipids, proteins, carbohydrates, nucleic acids). Every living organism contains much more oxygen than any element (up to 70%). For example, the body of an average adult human weighing 70 kg contains 43 kg of oxygen.

Oxygen enters living organisms (plants, animals and humans) through the respiratory system and the intake of water. Remembering that in the human body the most important respiratory organ is the skin, it becomes clear how much oxygen a person can receive, especially in the summer on the shore of a reservoir. Determining a person’s need for oxygen is quite difficult, because it depends on many factors - age, gender, body weight and surface area, nutrition system, external environment, etc.

Use of oxygen in life

Oxygen is used almost everywhere - from metallurgy to the production of rocket fuel and explosives used for road work in the mountains; from medicine to the food industry.

In the food industry, oxygen is registered as a food additive, as a propellant and packaging gas.

In the previous material, we gained an understanding of where a person gets it from. To understand the processes of the antioxidant system, which also has great functionality in improving the health of the body, one should understand the importance of oxygen for human health and life.

If we consider the air according to its components, we will see that among what we inhale it contains the following:

• 78% nitrogen;
• 21% oxygen;
• other gases 1% and contain 0.03% CO2.

Chemical elements with different abilities attract additional electrons; this ability depends on the position of any element in the periodic table. This attraction, called electronegativity, is expressed by its conventional units, and the higher they are, the greater the ability to attract electrons.

When two different atoms interact with each other, a pair of electrons will shift to the most electronegative atom. Oxygen is one of the most electronegative elements. It is also the most sought after component on Earth.

Oxygen is divided into two forms of existence: oxygen (O2) and ozone (Oz). It is a colorless gas, odorless, and acts as a vital substance.
Interacting with each element of the periodic table, it creates a huge number of compounds.

Oxygen is a necessary component to provide a person with life energy

The Earth stores free oxygen in its atmosphere. Bound oxygen is stored in the earth's crust, as well as in fresh and sea water. Oxygen provides the respiratory process, then, after the oxidation of organic compounds, it forms carbon dioxide and water, during which energy is released.

In other words, we receive the energy that is required every minute in our life, which is the result of the breakdown of the food we eat. The breakdown of food occurs under the influence of inhaled oxygen.

Now oxygen and physiology.

The most complex complex of changes occurring in the body at the physical, biological and physiological levels, in which the body receives and transforms substances and energy, and constantly exchanges them in the environment, is METABOLISM and energy. This process underlies the conversion of energy from free energy received
with complex organic compounds, electrical, mechanical and thermal. The relationship between the metabolism of fats, carbohydrates and proteins, accompanied by biochemical processes that regulate hormones, allows us to provide our cells with maximum energy.

Did you know that a person’s weight is 62% filled with oxygen?
For example, if your weight is 70 kg, then 43 kg of it is oxygen. I'll give you an interesting fact, for
Every day we eat 2 kg of oxygen and inhale 900 grams of air. For those who don’t know, information for you - Oz (ozone), as an oxygen form, is toxic.

Who doesn't need oxygen to live?

There is no need for oxygen in anaerobic bacteria and deep-sea inhabitants (their energy is based
substances obtained as a result of volcanic activity) All other living things need oxygen. Life on the planet is impossible without it. Its only 5-7 minute absence causes hypoxia (oxygen starvation) of tissues and causes death.

Food brings electrons and hydrogen protons to the body. Protons, for example, come from food in organic acids, and electrons are supplied by metals with variable valence and vitamins, in particular C and E. Biological oxidation receives the necessary substrate, consisting of glucose, and easily digestible dietary carbohydrates are converted into it, in turn.

Simply put, electrons are supplied by oxygen, and protons are supplied by hydrogen. Together, protons and electrons create covalent bonds (biosynthesis of a molecule). The vital elements of the body (proteins, nucleic acids, etc.) are also filled with oxygen. Breathing without it is meaningless; the oxidation of fats, proteins, amino acids, carbohydrates and other biochemical processes is also impossible without oxygen.

During the day, when we are alert, we consume a large amount of oxygen. It enters our body naturally and is inhaled through the lungs. Next, the precious biocomponent entering the blood begins to absorb hemoglobin, converting it into oxyhemoglobin, and then it is distributed throughout all our components (tissues and organs). But also
it also comes in bound form when we drink water. Having received oxygen, tissues spend it on the metabolic process, for the oxidation of various elements. The further path of oxygen is aimed at its metabolism to CO2 (carbon dioxide) and H2O (water) and ultimately it is excreted by the body - the kidneys and lungs.