Distribution of chemical elements in space. Which chemical element is the most common and why? In the solar atmosphere, there is one atom of oxygen per
The prevalence of elements in space is studied by cosmochemistry, and their distribution on earth is studied by geochemistry. In interstellar space there are ions and atoms of various elements, as well as groups of atoms, radicals and even molecules. There are especially many Ca ions in interstellar space. In addition to it, H, K, C atoms, sodium, O, titanium ions and other particles are scattered in space. The first place in abundance in the universe belongs to hydrogen. Chem. The composition of stars depends on many factors, including temperature. As the temperature increases, the composition of particles existing in the star's atmosphere becomes simpler. Thus, spectral analysis of stars with T = 10000-50000 shows lines of ionized hydrogen and helium and metal ions in their atmospheres. Radicals are already found in the atmospheres of stars with T=5000, and even oxide molecules are found in the atmospheres of stars with T=3800. Young red giant stars contain increased amounts of heavy metals. The chemical composition of a star reflects the influence of two factors: the nature of the interstellar medium and those nuclear reactions that develop in the star during its life. The initial composition of the star is close to the composition of the interstellar matter (gas and dust cloud) from which the star arose. There are stars in which hydrogen has turned into helium. Their atmosphere consists of helium. Carbon stars are relatively cool stars, their T=5000-6000. As the atomic mass of an element increases, its abundance decreases; even elements are more common than odd elements. Prevalence of elements in solar system. The atmosphere of the sun is in constant motion. 72 elements detected. Most of all H-75%, Non-24%, 1.2% for other elements. Quite a lot of O, C, nitrogen, sodium, iron, nickel, little lithium.
Clarks.
Clarks of elements are numbers expressing the average content of elements in the earth’s crust, the hydrosphere of the earth as a whole, cosmic bodies and other geochemical and cosmic systems. There are weight and atomic clarks. Elements with an even order make up 87% of the mass of the earth's crust, and with odd numbers only 13%, average chemical composition Earth as a whole was calculated based on data on the content of elements in meteorites. Clark serves as a standard for comparing lower or higher concentrations of elements in semi-deposited rocks or entire regions. Knowing them is important when searching for and industrially assessing agricultural deposits. Main elements: O, S, Al, Fe, Ca, Na, K, Mg, Ti, Mn. The amount of clarke decreases as the element number increases; the amount of light elements to iron decreases faster than heavy ones.
In the earth's crust: O2 – 47 Si – 29 Al – 8 Fe – 5 Ca – 3 Na – 3 K – 3 Mg – 2 Ti 0.5 Mn – 0.1
Concentration and dispersion of elements.
All elements are present everywhere, in every gram of water, rock, we are only talking about the lack of sensitive modern methods analysis. This is the proposition about the general dispersion of elements. Factors for dispersion of elements:
1. inability to produce compounds (He, Ar, Kr, Xe).
2. low melting and boiling points, as a result of which such peak elements turn into a gaseous state and dissipate.
3. low ionization potentials, as a result of which ions easily pass into an excited state.
4. low valence
5. high solubility of the main salts and compounds of this element.
Concentration factors:
1. average (high) values of elements
2. high temperatures melting and boiling
3. average valency and especially even
4. average, rather low values of the radii of atoms and ions
5. average ionization potential
6. parity of atomic ions
7. high density
Substance concentration in natural systems 0 Vernadsky's law on the dispersion of elements. Everything is everywhere. Substance concentration in natural systems 0 Meteorites. Meteorites are fragments of cosmic matter, of 2 types: stone and iron, or silicate and metal. Their substance contains 3 phases: 1. iron-nickel or metal 2. sulfide or troilite 3. stone or silicate. Stones are divided into chondrites and achondrites. Chondrites, a primitive type of meteorite, are products of much more complex processes of chemical differentiation of matter. They consist of olivine, pyroxene, nickel iron and plagioclase. Achondrites are a group of stony meteorites characterized by great diversity. They have a crystalline structure, many of them are very similar to igneous rocks on earth. They are divided into 2 groups: calcium-poor and calcium-rich. 16-1 Differences in the elemental composition of the earth’s lithosphere from the composition of the surface of the moon, Mars, Venus and the giant planets. Venus is close in size and average density to the earth. It has the densest and most powerful atmosphere of all the inner planets. The atmosphere of the planet consists almost entirely of CO2 (93-97%), the presence of oxygen, nitrogen, water has been detected, the nitrogen content along with inert gases reaches 2-5%, and the amount of O is 0.4%, T = 747 K, and P =90*10^5 Pa. Mars has the lowest density, there is a rarefied atmosphere, the atmospheric pressure at the surface does not exceed 800 Pa, 2 orders of magnitude less than on earth. The main component of the atmosphere is CO2, the content of NO2 impurities was found, the content of O2 and O3 is negligible. The moon is devoid of atmosphere. Increased gravity anomalies in areas of the lunar seas. Based on indirect data, it can be assumed that the outer planets contain a lot of helium. In the central parts of the outer planets there is helium (Uranus, Neptune, Jupiter, Saturn). Municipal Educational Institution Secondary School No. 7 Buguruslan, Orenburg region Essay
on the topic of:
"Space Chemistry"
Completed Utegenov Timur Student of class 7A 2011
Introduction
If it attracts you with its harmony And amazes with its immensity - It means you have a living heart beating in your chest, This means it will be able to resonate with the innermost, words about life in space. B Unfortunately, man has learned to use only those materials that are on the surface of the Earth, but the earth's resources are depleted. From there the question: “Are there any chemical elements in space that are at least a little similar to those on Earth and can they be used for our own purposes?” This is the relevance of my chosen topic. Goals of work: 1. Explores the chemistry of planets, stars, interstellar space. 2. Get acquainted with the science of Cosmochemistry. 3.Learn and talk about new and interesting facts regarding space chemistry. 4. Use the acquired knowledge in the future. Today there is even a separate science, cosmochemistry. Cosmochemistry is the science of the chemical composition of cosmic bodies, the laws of abundance and distribution of chemical elements in the Universe, the processes of combination and migration of atoms during the formation of cosmic matter. The most studied part of Cosmochemistry is geochemistry. Cosmochemistry studies predominantly “cold” processes at the level of atomic-molecular interactions of substances, while “hot” nuclear processes in space - the plasma state of matter, nucleogenesis (the process of formation of chemical elements) inside stars, etc. - are mainly dealt with by physics. Cosmochemistry is a new field of knowledge that received significant development in the 2nd half of the 20th century. mainly due to the successes of astronautics. Previously, studies of chemical processes in outer space and the composition of cosmic bodies were carried out mainly through spectral analysis of the radiation of the Sun, stars and, partly, the outer layers of planetary atmospheres. This method allowed the element helium to be discovered on the Sun before it was discovered on Earth. 1. Chemistry of the Earth. For geologists studying our planet, it is most important to know the most general laws that determine the behavior of matter on the surface of the earth's crust, in its thickness and in the depths of the globe. A geologist cannot search blindly. He must know in advance where he can find iron, where uranium, where phosphorus, where potassium. He must know what conditions create carbon deposits on Earth: where to look for coal, where for graphite and where for diamonds. A geologist needs to know which elements accompany each other in the earth's crust, he must know the laws of formation of joint deposits of various elements. In complex, enormous chemical processes that have been occurring in the earth’s crust and on its surface for hundreds of millions of years, continuing to this day, elements similar in their position in the periodic table have similar geochemical fates. This allows geochemists to trace their movement in the earth's crust and find out the laws that distribute them on the Earth's surface. The composition of the earth's crust includes: If we compare the quantities of iron, cobalt and nickel available throughout the Earth - elements that stand side by side in the eighth group of the periodic system, it turns out that the globe consists of 36.9% iron (atomic number 26), cobalt (atomic number 27) 0.2%, nickel (atomic number 28) by 2.9%. The geochemical behavior of various elements is determined, first of all, by the structure of the outer electron shells in their atoms, the sizes of the atoms and the corresponding ions. Elements with complete outer electron shells (noble gases) exist only in the atmosphere; They do not enter into chemical compounds under natural conditions. Even helium and radon, formed during radioactive decay, are not completely captured by rocks, but are continuously released from them into the atmosphere. Rare earths that appear in the same cell of the table are almost always found together in nature. The same ores always contain both zirconium and hafnium together. Geologists know well that osmium and iridium should be looked for in the same place as platinum. In the periodic table of Mendeleev they stand together in the eighth group, and are also inseparable in nature. Deposits of nickel and cobalt accompany iron, and in the table they are in the same group and in the same period. The main thickness of the earth's crust consists of a few minerals; all these are chemical compounds of elements located mainly in short periods and at the beginning and end of each of the long periods of the table. Moreover, light elements with low serial numbers predominate among them. These elements make up the bulk of silicate rocks. Elements that stand in the middle of long periods in the periodic table form ore deposits, most often sulfide deposits. Many of these elements are found in a native state. Both the abundance and the geochemical behavior of an element (its migration in the earth’s crust) are determined by its position in the periodic table. The abundance depends on the structure of the atomic nucleus, and the geochemical behavior depends on the structure of the electron shell. Therefore, the periodic table of elements is necessary for a geochemist. Without it, geochemistry could not have arisen and developed. This science establishes general patterns in the mutual coexistence of chemical elements in rocks and ores. It allows a geologist to find mineral deposits in the earth's crust. Mendeleev's periodic law is a reliable and proven compass for the geochemist and geologist. At the beginning of my work, I said that we would talk about the chemistry of space, but for some reason I started talking about the chemical composition of the Earth... But, firstly, the Earth is also a celestial body, and, secondly, you need to know the chemical composition of the Earth in order compare it with the composition of meteorites and other cosmic bodies flying to us on Earth from the mysterious depths of outer space. TO iron 91.0%, cobalt 0.6%, nickel 8.4%. If we compare these numbers with the relative distribution of these elements on the globe, given above, we get an absolutely amazing coincidence: it turns out that on Earth, of these three elements, we account for iron 92%, cobalt 0.5%, nickel 7.5%, T Each of the elements both on Earth and in meteorites has almost the same isotopic composition. For example, repeated analyzes of the isotopic composition of sulfur extracted from the ash and lava of numerous volcanoes located in different parts of the globe have shown that sulfur is the same everywhere. Everywhere the relationship between the amounts of stable isotopes of sulfur -32 and sulfur-34 is the same. It is equal to 22,200. The isotopic composition of sulfur from meteorites - the only representatives of the Cosmos accessible to direct study - is exactly the same as on Earth. It further turned out that the most common elements are the same. Even the relationship between them is the same here and there. The alternation of elements with even and odd atomic numbers in the periodic table is also observed in the same way both here and there. One could, of course, give many more examples showing the great similarity in the behavior of chemical elements on Earth and in outer space, and note many more general patterns. Could this be random? Of course not. No matter where random guests from the Universe fly to us on Earth - perhaps these are parts of comets that belonged to the solar system; perhaps these are fragments of small planets; perhaps these are messengers from an alien stellar world - one thing is important: by their chemical composition, by the relationship between elements, by the chemical compounds that are found in meteorites, they tell us that the action of the great law of Mendeleev is not limited to the boundaries of our planet. It is the same for the entire Universe, where atoms with their electron shell can exist. From this the conclusion is: “Matter is united everywhere.” 3. Chemical composition of stars.
In the depths of stars, under conditions unimaginable for Earth, at temperatures of hundreds of millions of kelvins and incomprehensibly enormous pressures, many different nuclear chemical reactions take place. Nowadays, there is already a vast field of science, the fascinating chemistry of the inaccessible - nuclear astrochemistry. It clarifies the most important questions for all science: how the elements were formed in the Universe, where and what elements arise, what is their fate in the eternal development of the universe. The methods of this science are unusual. She uses both observation - she studies the composition of stellar atmospheres using spectroscopy - and experiment - she studies the reactions of fast particles in terrestrial accelerators. Theoretical calculations allow scientists to look into the depths of stars, where a lot of interesting things have already been discovered and a lot of mysterious things lie hidden. It has been found, for example, that in the central regions of stars, at ultra-high temperatures and pressures, where the rate of hydrogen “burnout” is especially high, where its quantity is small, and the helium content is high, reactions between helium nuclei are possible. Mysterious beryllium nuclei - 8 are born there (they cannot exist at all on Earth), and the strongest nuclei appear there: carbon - 12, oxygen - 16, neon - 20 and other nuclei of the “helium” cycle. Nuclear chemical reactions that produce neutrons have also been found in stars. And if there are neutrons, then we can understand how almost all other elements appear in stars. But science still faces many mysteries along this path. The variety of stars in the Universe is incomprehensibly huge. IN It was also possible to trace the amazing mechanisms of the formation of new nuclei. It turns out that not only due to ultra-high temperatures, nuclei have such high energy that they are able to overcome electrostatic repulsion and react with each other. Many elements could not be formed in this way at all. Deuterium, lithium, beryllium, boron at the high temperature that exists inside stars react very quickly with hydrogen and are instantly destroyed. These elements in the universe are “cooked” in cold “kitchens,” perhaps on the surface of stars in stellar atmospheres, where powerful electric and magnetic fields arise, accelerating particles to ultra-high energies. Stellar "factories" where elements are created pose strange mysteries for scientists related to mysterious neutrino particles. Scientists are beginning to suspect that the role of these elusive ghost particles is not as insignificant as it seemed quite recently. It turned out that nuclear chemical processes are possible in which most of the energy generated in a star is carried away not in the form of radiation, but only with neutrinos. But for the star this means disaster. A star exists in a state of equilibrium due to the pressure of stellar gas and light pressure, which balance the gravitational forces. If energy begins to be carried away from the interior of the star only with neutrinos, which penetrate the thickness of stellar bodies without resistance, at the speed of light, then the star will instantly be compressed by the forces of gravitational attraction. Perhaps this is how still incomprehensible stars are formed - white dwarfs, the density of matter in which can reach many thousands of tons per 1 cm3. Perhaps such processes also give rise to those gigantic catastrophes during which Supernovae are born. But there is no doubt that this, one of the greatest mysteries of nature, will be solved. We will also learn the secret of hydrogen reserves in stars and in cosmic space; the processes leading to its formation and to the formation of “young” hydrogen stars will be found. The question of the appearance of Supernovae in the universe is extremely important. The mystery of how such a colossal amount of energy is generated that is capable of scattering a star and turning it into a nebula must be solved. This is exactly what happened, for example, in 1054. A Supernova broke out in the constellation Taurus and, fading, turned into the Crab Nebula. In our time, this nebula already extends over hundreds of billions (1012) kilometers. The most interesting thing is that the Supernova explosion, gradually fading, loses its brightness as if it consisted of the isotope California-254. Its half-life is 55 days. – exactly coincides with the period of decrease in the brightness of Supernovae. But, perhaps, the main task of astrochemistry is to find out how hydrogen appears in the Universe. Indeed, in countless stellar worlds there is a continuous destruction of hydrogen, and its total reserves in the Universe must decrease. And many scientists in the West have come to the difficult and gloomy conclusion about the “hydrogen death” of the Universe. They believe that in the Universe, one after another, stars are extinguishing, having exhausted their hydrogen reserves. And these previously brightly shining luminaries, one after another, turn into cold, dead worlds, destined to forever float around in outer space. The gloomy conclusion about the “hydrogen death” of the Universe is logically flawed and incorrect. It is refuted by experimental facts and the achievements of modern science - the chemistry of the Universe. The achievements of science, which introduced us to the secrets of inaccessible stars, their composition, nature, mysterious processes occurring in their depths, are based on knowledge of the nature of the atom and its structure. This knowledge is embodied in Mendeleev's periodic law. But one should not think that the periodic law will forever remain frozen and unchanged. No, it itself develops, including more and more content, more deeply and more accurately reflecting the truth of the laws of nature. The law of periodicity is also characteristic of the structure of atomic nuclei. This allows us to hope for a final decision about the relative stability of the elements in the world and about the composition of all celestial bodies. Not so long ago, science accepted that interstellar space was empty. All the matter in the Universe is concentrated in the stars, and there is nothing between them. Only within the solar system, somewhere along unknown paths, do meteorites and their mysterious cousins, comets, wander. The paths to the emergence of one of the sciences of the future - outer space chemistry - are surprisingly complex and unexpected. In the dark and terrible years of the fascist occupation in the small Dutch town of Leiden, at a secret meeting of an underground scientific circle, the young student Van de Holst made a report. Based on the theory of atomic structure (which, as we already know, was developed by science on the basis of Mendeleev’s periodic law), he calculated what the longest wave in the spectrum of hydrogen radiation should be. It turned out that the length of this wave is 21 cm. It belongs to short radio waves. Unlike the well-studied visible spectrum emitted by hot hydrogen, its radio emission can also occur at low temperatures. Van de Holst calculated that on Earth such radiation in a hydrogen atom is unlikely. It is necessary to wait many millions of years until electrons move in a hydrogen atom, which is accompanied by the emission of radio waves 21 cm long. In his report, the young scientist made an assumption: if hydrogen is present in the boundless cosmic space, one can hope to detect it by radiation at a wave of 21 cm. This prediction was justified. It turned out that from the vast depths of the Universe, amazing radio messages about the secrets of the universe that interstellar hydrogen brings to us always come to us on Earth, without stopping either night or day, on a wave of 21 cm. A 21 cm wave rushes towards our planet from such distant corners of the Universe that it takes thousands and millions of years until it reaches the antennas of radio telescopes. She told scientists that there is no void in space, that there are invisible clouds of cosmic hydrogen in it that extend from one star system to another. It was even possible to determine the extent and shape of these hydrogen accumulations. For a wave of 21 cm, there are no obstacles in space. Even the black, impenetrable clouds of cosmic dust that hide vast areas of the Milky Way from the view of the researcher are completely transparent to the cold radiation of hydrogen. And these waves now help scientists understand the nature of the substance from which the distant stars of not only the Milky Way are built, but also the most distant nebulae lying at the very edge of the part of the Universe accessible to us. Vast star worlds, separated by distances in empty boundless space, now find themselves connected into a single whole by giant hydrogen clouds. It is difficult to trace continuity in the development of scientific ideas, but there is no doubt that there is a direct and continuous connection between the bold prediction of the young Dutch student and the great idea of Mendeleev. This is how hydrogen was found in interstellar space. Boundless world space cannot be considered empty. Now, in addition to hydrogen, many other elements have been found in it. The chemistry of space is very peculiar. This is ultra-high vacuum chemistry. The average density of matter in space is only 10-24 g/cm3. Such a vacuum cannot yet be created in physics laboratories. Atomic hydrogen plays the most important role in the chemistry of outer space. The next most common is helium, it is ten times less; Oxygen, neon, nitrogen, carbon, silicon have already been found - there are negligibly few of them in outer space. It turned out that the role of interstellar matter in the universe is enormous. It accounts, at least within our Galaxy, for almost half of all matter, the rest is in stars. In recent years, absolutely amazing discoveries have been made in the chemistry of interstellar space. It all started with the unexpected discovery of a complex molecule called ceanoacetylene (HC3N) in space. Before cosmochemists had time to explain how an organic molecule of such a complex composition and structure arises in interstellar space, suddenly, with the help of a radio telescope in the constellation Sagittarius, giant clouds of the most common chemical compound on Earth and completely unexpected for space - formic acid (HCOOH) were discovered. The next discovery was even more unexpected. It turned out that there are clouds of formaldehyde (HCOH) in outer space. This in itself is already quite surprising, but the fact that different cosmic formaldehyde clouds have different isotopic compositions remains completely inexplicable. It is as if the history of the interstellar medium is different in different parts of the Galaxy. Then came an even stranger discovery: ammonia (NH3) was discovered in a small cloud of interstellar dust lying somewhere towards the center of our Galaxy. Based on the intensity of radio emission from cosmic ammonia, it was even possible to measure the temperature of this region of space (25 K). The mystery of cosmic ammonia is that it is unstable under these conditions and is destroyed under the influence of ultraviolet radiation. This means that it intensively arises - is formed in space. But how? This is unknown for now. The chemistry of interstellar space turns out to be surprisingly complex. Formamide molecules have already been found - six-atom molecules consisting of atoms of four different elements. How do they arise? What is their fate? Molecules of methylceanide (CH 3 CN), carbon disulfide (CS 2), carbon sulphide (COS), and silicon oxide (SiO) were also found. In addition, the simplest radicals were discovered in space: for example, methine (CH), hydroxyl (OH). When the existence of hydroxyl was established, a search for water was undertaken. Where there is hydroxyl, there must be water, and it has actually been found in interstellar space. This discovery is particularly interesting and important. In space there is water, there are organic molecules (formaldehyde), there is ammonia. These compounds, reacting with each other, can lead to the formation of amino acids, which has been confirmed experimentally under terrestrial conditions. What else will be discovered in the interstellar “emptiness”? More than 20 complex chemical compounds were found in it. Probably, amino acids will also be discovered. Amazing cosmic clouds of organic compounds, such as the cloud of cyanoacetylene in the constellation Sagittarius, are quite dense and extensive. Calculations show that such clouds should be compressed under the influence of gravity. Might it not be possible that the absolutely fantastic assumption is that the planets, during their formation, already contain complex organic compounds - the basis of primitive forms of life? Perhaps, it becomes quite acceptable to seriously discuss the seemingly completely impossible question: “What is older - the planets or the life on them?” Of course, it is difficult to guess what the answer will be. One thing is clear: there are no unsolvable questions for science. A new science is emerging before our eyes. It is difficult to foresee the path of its development and to predict what even more amazing discoveries cosmic chemistry will lead to. M Time passed. Information about the Moon became more and more accurate. In 1840, the lunar surface was first displayed on a photographic plate. In October 1959, the Soviet space station Luna 3 transmitted an image of the far side of the Moon to Earth. And so on July 21, 1969, a human footprint was imprinted on the surface of the Moon. American cosmonauts, and then Soviet automatic stations, brought lunar rocks to Earth. Moonstones are special - their composition is affected by a lack of oxygen. Metals are not found in their highest oxidation states; only ferrous iron is found. There was no free water or atmosphere on the Moon. All volatile compounds that arose during magmatic processes flew into space, and a secondary atmosphere could not arise. In addition, on the Moon, the process of melting (formation of the crust) proceeded very quickly and at higher temperatures: 1200 - 1300 ° C, while these processes on Earth took place at 1000 - 1100 ° C. The Moon always faces the same side towards the Earth. On a clear night you can see dark spots on it - the lunar “seas”, which Galileo discovered. They occupy about a third of the visible side of the Moon. The rest of its surface is highlands. Moreover, on the other side, invisible to us, there are almost no “seas”. The rocks that make up the high-mountain back side of the night star and the “continent” of the side visible to us are lighter than the rocks of the “seas”. N And the Lunar mountains, and the craters, and the lunar “seas” form the “lunar landscape”. It is very possible that the Earth in the early era of its geological history was eaten away by craters and was similar in landscape to the present Moon. But the powerful processes of rock destruction inherent to the Earth buried the primary relief under a layer of sediment. The destruction of terrestrial rocks - weathering - occurs under the influence of water, living organisms, oxygen, carbon dioxide and other chemical factors, as well as temperature changes. There is no atmosphere on the Moon, no water, and no organisms, which means that the oxidation process, like other chemical reactions, is almost absent there. Therefore, lunar rocks mainly experience physical and mechanical fragmentation, while terrestrial rocks, when destroyed, undergo a deep chemical restructuring. Moon rocks turn to dust under the influence of a sharp change in temperature between lunar day and lunar night. Rocks are affected by both galactic radiation and the “solar wind” - radiation from the Sun. We must not forget the meteorites crashing into the surface of the Moon at tremendous speed. As a result of all these processes, a layer of fine-grained lunar soil appeared on the dense rocks of the Moon. It covers the “seas” with a thick layer. It also exists on the surface of the highland, continental regions of the Moon. Galactic radiation penetrates about a meter into the body of the Moon, and nuclear transformations occur in the rocks under the influence of protons. Thanks to proton bombardment, radioactive isotopes (23AI, 22Na, etc.) are common on the Moon, which are almost absent in earthly rocks. There are other differences too. For example, lunar rocks contain more argon than terrestrial rocks. And one more chemical feature - in all likelihood, there are no mineral deposits on the Moon. The fact is that the formation of ore bodies requires hydrothermal solutions, and there has never been free water in the thickness of the Moon. But some lunar rocks contain about 10% titanium. Stones from space - meteorites - have been familiar to people for a long time. But the first pieces of rock from the Moon came to us quite recently. They were delivered to Earth by astronauts of the American Apollo spacecraft and the Soviet automatic stations Luna - 16 and Luna - 20. It's amazing to hold a piece of the Moon in your hands! Scientists have been talking about the moonstone for centuries, poets have sung about it, so much has been written about it! And only in our days has man been given an exceptional opportunity to compare the material composition of terrestrial, meteorite and lunar stones. Stone meteorites are mainly composed of simple silicates, the number of minerals in them barely reaches a hundred. There are slightly more minerals in lunar rocks than in meteorites—probably several hundred. And more than 3 thousand minerals have been discovered on the surface of the Earth. This indicates the complexity of terrestrial chemical processes compared to lunar ones. It is appropriate to recall here that the chemical elemental composition of stony meteorites (chondrites) is very similar to the composition of the Sun. In stony meteorites and on the Sun, the abundance of chemical elements and the ratios between them are almost the same (with the exception of gases that evaporated during the formation of meteorites). All chemical elements found in the Sun are also found in meteorites. In addition, the Si/Mg ratio is the same both on the Sun and in meteorites, and is close to unity. When it turned out that the stones brought from the lunar “seas” turned out to be fragments of basaltic rocks, it became clear that the lunar crust has a lot in common with the Earth. The basalts of the Moon, erupted during lunar volcanism, have a slightly different chemical composition than chondrites. Thus, the Si/Mg ratio in them is not equal to one, but approximately 6 (as in terrestrial basalts). The composition of these rocks no longer corresponds to the primary composition of the Sun, but they were melted from lunar material very close to stony meteorites. Suffice it to say that the average density of the Moon is the same as that of stony meteorites - 3.34 g/cm3. The earth has a density of more than 5, and yet the earth’s crust is mainly composed of basalts. This means that the Moon probably lacks a heavy iron core. AND In the highlands of the Moon, it is not basalts that predominate, but other rocks, the so-called anorthosites, consisting mainly of the mineral anorthite. On Earth, such rocks are found among the most ancient rocks on mountain shields. Terrestrial anorthosites have a venerable age - they are up to 3.5 billion years old. All anorthosites, including lunar ones, contain a lot of aluminum and calcium and some iron, vanadium, manganese, and titanium. Meanwhile, in “marine” lunar basalts the content of iron and titanium is very high. The discovery of the mode of formation of lunar anorthosites would clarify terrestrial geological processes of the distant past. It can be assumed that anorthosites arise during the crystallization differentiation of gabbro-basaltic magma. On the Moon, anorthosite crystallizes during the very rapid outpouring of magma in the vacuum of space. Everything suggests that the formation of anorthosite requires water and high temperature. The lunar magma was hot, however, there are signs that it contained few volatile components: water, gases, carbon dioxide. True, such volatile compounds could easily escape from the Moon into space. There is still much that is unclear about the origin of anorthosites, but the discovery of these rocks in the lunar highlands has revived old geological ideas about the primary anorthosite crust of the Earth. The concentration of nickel in the rocks of the Moon is very interesting. It is scarce in monolithic marine basalts. But in the soil (crushed rock) there is half an order of magnitude more of it. And the anorthosites of the continental regions of the Moon contain a lot of nickel not only in the soil, but also in pieces of rock. And the most interesting thing is that sprayed metallic iron containing nickel was found in the soil. In all likelihood, these are particles of the metal phase of meteorites. It was possible to calculate that the lunar soil contains 0.25% of this iron alloy, or 2.5% of the stone meteorite substance. This means that many millions of tons of matter were brought to the Moon from space. With the help of moon rocks delivered to Earth, the absolute “geological” age of our night star was determined. It turned out that the Moon is about 4.6 * 109 years old, i.e. she is the same age as Earth. At the same time, individual crystalline rocks (mainly basalts of the lunar “seas”) are a billion years younger: they are about 3.0 * 109 years old. 6. Chemical composition of the planets. WITH Mercury- the planet closest to the Sun. But we still know very roughly what is happening on the planet. Its mass is too small (0.054 Earth's), the temperature on the solar side is too high (more than 400 ° C), and molecules of any gas leave the surface of the planet at enormous speed, flying into outer space. Mercury is probably covered with silicate rocks similar to those on Earth. On Venus Soviet scientists sent several automatic laboratories. T The Soviet automatic interplanetary stations "Venera - 4", "Venera - 5" and "Venera - 6" sent from Earth made a direct analysis of the composition of atmospheric gases, measured pressure and temperature. The information received was transmitted to Earth. The composition of the atmosphere of this planet is now reliably known: carbon dioxide (CO 2 ) about 97%, nitrogen (N 2) no more than 2%, water vapor (H 2 O) about 1%, oxygen (O 2) no more than 0.1%. Life is impossible on the surface of Venus. The space laboratory thermometer showed a temperature of about 500 o C, and the pressure was about 100 atm. The surface of Venus is (almost certainly) a hot rocky desert. WITH The most interesting, amazing and mysterious planet from the point of view of chemistry is Jupiter. Radio emission from Jupiter has recently been discovered. What processes can generate radio waves on this cold giant is a mystery. Theorists have calculated that the planet's core should be liquid. It is surrounded by a shell of metallic hydrogen, and pressures of a million atmospheres reign there. Scientists are persistently trying to obtain metallic hydrogen in laboratories. Based on thermodynamic calculations, they are confident of success. Jupiter is shrouded in a dense atmosphere tens of thousands of kilometers thick. Chemists have discovered many different compounds in Jupiter's atmosphere. All of them, of course, are built in full accordance with the periodic law. Jupiter is 98% hydrogen and helium. Water and hydrogen sulfide were also detected. Signs of methane and ammonia were found. The average density of Jupiter is very low - 1.37 g/cm3. F The outer surface of Jupiter is very cold - from -90 to -120°C. Consequently, inside its atmosphere there must be areas where conditions differ little from those on Earth. The thickness of such a zone is by no means small, about 3000 km. In this zone, temperature fluctuations range from -5 to +100°C. The water here should be liquid, and other atmospheric compounds should be gaseous. Astronomers believe that the outside of Jupiter is covered with a cloudy shell consisting of solid particles of ice and ammonia. That's why it shines so brightly in the sky. Through a telescope, stripes of mysterious clouds floating at gigantic speeds are clearly visible on the surface of Jupiter. This is the kingdom of hurricanes and monstrous thunderstorms. Scientists tried to recreate the conditions of Jupiter's atmosphere in the laboratory. The results were unexpected. Under the influence of electrical discharges (thunderstorms), ionizing and ultraviolet radiation (sunlight and cosmic rays) in a gaseous environment similar in composition to the atmosphere of Jupiter, complex organic compounds arose: urea, adenine, carbon dioxide, even some amino acids and complex hydrocarbons. In addition, red and orange cyanopolymers were obtained. Their spectra turned out to be similar to the spectrum of the mysterious red spot on Jupiter. Scientists have a question: is there life on Jupiter? For our earthly organisms, the atmosphere of this planet is poison. But maybe this is a zone of primary forms of life, an ocean of pre-biological compounds necessary for the emergence of the most primitive, simplest forms of life? Or maybe they have already appeared there? WITH WITH Chemical composition Pluto also unknown, but its density (about 2 g/cm3) indicates that it is likely composed of a mixture of 70% rock and 30% water ice, much like Triton. The light areas on the surface are possibly covered with nitrogen ice and small additions of (solid) methane, ethane and carbon monoxide. The composition of the dark regions of Pluto's surface is unknown, but it may be created from primordial organic material or through photochemical reactions caused by cosmic rays. Little is known about Pluto's atmosphere, but it is likely composed mostly of nitrogen with minor amounts of carbon monoxide and methane. A The amazing achievements of space chemistry have made it possible to begin research into the processes occurring on the surface of distant, as yet inaccessible worlds. This leads to a very important conclusion: the most beautiful planet is our native Earth. It is the duty of every person to take care of all its riches and beauty. Conclusion Our knowledge of the chemical composition of the Universe comes from spectroscopic studies of radiation from the Sun and stars, analysis of meteorites, and from what we know about the composition of the Earth and other planets. Spectroscopic observations make it possible to identify the elements responsible for the emissions, and from careful analysis of the intensities of the spectral lines, rough estimates can be made of the relative quantities of the various elements present in the outer parts of the emitted body. The data obtained in this way confirms the assumption that the Universe consists of the same elements. And the data provided proves this. Bibliography.
1. Internet; 2. G. Hancock, R. Bauval, J. Grigsby “Secrets of Mars” 3. V. N. Demin “Secrets of the Universe” Modern astronomers know about three and a half thousand exoplanets, which are located at a distance from us from four to twenty-eight thousand light years. Some of them are very . It will be difficult to get to any of them in the foreseeable future - unless humanity makes a huge technological leap. Nevertheless, exoplanets are already of great interest from the point of view of astrochemistry. This is our new material, written in partnership with the Ural Federal University. The bulk of the matter of the Universe (if we talk about baryonic matter) is hydrogen - about 75 percent. Helium comes in second place (about 23 percent). However, a wide variety of chemical elements and even complex molecular compounds, including organic ones, can be found in space. Astrochemistry studies the processes of formation and interaction of chemical compounds in space. Representatives of this specialty are very interested in studying exoplanets, because a variety of scenarios can be realized on them, which will lead to the appearance of unusual compounds. The main tool for obtaining information about the chemical composition of distant objects is spectroscopy. It uses the fact that atoms of chemical elements (or molecules of compounds) can emit or absorb light only at certain frequencies corresponding to the transitions of the system between different energy levels. As a result, an emission (or absorption) spectrum is formed, from which the substance can be unambiguously identified. It's like fingerprints, but for atoms. A clear example of the decomposition of light into a spectrum is a rainbow. To us, transitions from one color to another seem smooth and continuous, but in fact, some colors are not in the rainbow, because certain wavelengths are absorbed by the hydrogen and helium contained in the Sun. By the way, helium was first discovered precisely by observing the spectrum of the Sun (that’s why it is called “helium”, from the ancient Greek ἥλιος - “sun”), and it was isolated in the laboratory only 27 years later. This was the first successful example of using spectroscopy to study stars. Fraunhofer absorption lines against the background of the continuous spectrum of the solar photosphere. Wikimedia commons In the simplest case of a hydrogen atom, the emission spectrum is a series of lines corresponding to transitions between levels with different values of the principal quantum number n (this picture is well described by the Rydberg formula). The most famous and convenient for observations is the Balmer Hα line, which has a wavelength of 656 nanometers and lies in the visible spectrum. For example, on this line, astronomers observe distant galaxies and recognize clouds of molecular gas, which for the most part consist of hydrogen. The following series of lines (Paschen, Brackett, Pfund, and so on) lie entirely in the infrared range, and the Lyman series is located in the ultraviolet region. This makes observations somewhat difficult. At the same time, molecules of complex compounds have another way to emit light quanta, in some sense even simpler. It is connected with the fact that the rotational energy of a molecule is quantized, which also allows them to emit in lines (in addition, they can emit a continuous spectrum). The energy of such light quanta is not very high, so their frequency is already in the radio range. One of the simplest rotational spectra belongs to the carbon monoxide molecule CO, from which astronomers also often recognize clouds of cold gas when they cannot see hydrogen in them. Radio astronomy methods have also made it possible to find methanol, ethanol, formaldehyde, hydrocyanic and formic acid, as well as other elements, in molecular clouds. For example, it was with the help of a radio telescope that scientists discovered alcohol in the tail of Comet Lovejoy. The easiest way to use spectroscopy methods is to study the chemical composition of stars. In this case, astronomers study the absorption spectra rather than the emission spectra of the elements. In fact, the light from them is easy to observe, especially in the visible range. True, the chemical composition of stars in themselves is usually not very interesting: for the most part they consist of hydrogen and helium with a small admixture of heavy elements. Heavier elements are produced in supernova explosions and can also be observed. For example, some scientists argue that the recent merger of two neutron stars should have produced huge amounts of gold, platinum and other elements from the last rows of the periodic table. But one way or another, very complex or organic compounds cannot exist in stars, since they necessarily disintegrate due to high temperatures. Clouds of cold interstellar gas are another matter. They are very rarefied and emit much weaker radiation than stars, but they themselves are much larger. And their composition is more interesting. You can find a huge number of different molecules in them - from simple diatomic ones to relatively complex polyatomic organic compounds. Among complex molecules, it is especially worth highlighting “prebiotic” compounds, for example, aminoacetonitrile, which can participate in the formation of glycine, the simplest amino acid. Some scientists suggest that ribose, one of the basic building blocks of organic life, may also form in molecular clouds. If such compounds find themselves in favorable conditions, this will already be a stepping stone for the emergence of life. Image of the Orion Nebula M42 obtained by the Kourovsky Astronomical Observatory of UrFU. The red color is the result of recombination in the Hα emission line at a wavelength of 656.3 nanometers. Unfortunately, it is difficult to use spectroscopy to determine the chemical composition of exoplanets. Still, to do this, you need to register the light from them, and the star around which the planet revolves prevents this from being done, since it shines much brighter. Trying to observe such a system is like looking at the light of a match against a spotlight. However, some information about an exoplanet can be obtained without directly measuring its emission spectrum. The trick is this. If a planet has an atmosphere, it should absorb some of the star's radiation, and in different spectral ranges in different ways. Roughly speaking, at one wavelength the planet will appear slightly smaller, and at another wavelength it will appear slightly larger. This allows us to make assumptions about the properties of the atmosphere, in particular, its chemical composition. This type of observation works especially well on hot planets close to their stars because their radii are easier to measure. In addition, the chemical composition of the planet must be related to the composition of the gas and dust cloud from which it formed. For example, in clouds with a high ratio of carbon atoms to oxygen atoms, the resulting planets will consist predominantly of carbonates. On the other hand, the chemical composition of a star formed from such a cloud should also reflect its composition. This allows us to make some assumptions based on studying the spectrum of just one star. Thus, astronomers from Yale University analyzed data on the chemical composition of 850 stars and found that in 60 percent of the systems, the concentrations of magnesium and silicon in the star indicate that rocky planets similar to Earth may be near it. In the remaining 40 percent, the chemical composition of the stars tells us that the composition of the planets around them must be significantly different from Earth's. Generally speaking, recently direct spectroscopy of especially hot planets against the background of dim stars has become possible thanks to the increased accuracy of measuring instruments. In this case, it is already possible to search in their light for traces of various chemical elements and complex compounds. For example, using the CONICA infrared spectrograph mounted on the VLT telescope and combined with the NAOS adaptive optics system, scientists were able to measure the spectrum of the exoplanet HR 8799 c, which orbits a white dwarf and is so hot that it emits light itself. In particular, from an analysis of its spectrum it followed that the planet’s atmosphere contained less methane and carbon monoxide than expected. Also, just recently, astronomers measured the spectrum of another “hot Jupiter” with titanium oxide in its atmosphere. However, directly measuring the spectrum of cooler rocky planets (where life is more likely to exist) is still very difficult. Image of the HR 8799 system. Planet HR 8799 c is in the upper right corner Jason Wang et al / NASA NExSS, W. M. Keck Observatory The composition of a planet can also be determined indirectly by calculating its density. To do this, you need to know the radius and mass of the planet. The mass can be found by observing the gravitational interaction of a planet with a star or other planets, and the radius can be estimated by the change in the brightness of a star as a planet passes across its disk. Obviously, gas planets should have a lower density compared to rocky ones. For example, the average density of the Earth is approximately 5.5 grams per cubic centimeter, and astronomers rely on this value to search for habitable planets. At the same time, the density of the “loosest hot Jupiter” is 0.1 grams per cubic centimeter. On the other hand, exoplanets can be studied without leaving the laboratory at all, no matter how strange it may sound. We are talking about modeling (mostly numerical) the chemical and physical processes that should occur on them. Due to the fact that the conditions on exoplanets can be the most exotic (pardon the pun), substances on them can also be formed in the most unusual, “impossible” conditions under our usual conditions. Most discovered exoplanets belong to “hot Jupiters” - gas giants that are very heated due to their short distance to the star. Of course, this does not necessarily mean that such planets predominate in star systems, just that they are easy to find. The temperature of the atmosphere of such giants can exceed a thousand degrees Celsius, and it consists mainly of silicate and iron vapors (at this temperature it begins to evaporate, but does not yet boil). At the same time, the pressure inside these planets must reach enormous values, at which hydrogen and other gases familiar to us turn into solid aggregate states. Experiments to simulate such extreme conditions have been carried out for a long time, but for the first time metallic hydrogen was used only in January of this year. On the other hand, in the depths of rocky planets, high pressures and temperatures can also be reached, and the “zoo” of chemical elements there can be even larger. For example, according to some estimates, the pressure inside rocky planets with masses of several Earth masses can reach values of up to 30 million atmospheres (inside the Earth the pressure does not exceed four million atmospheres). With the help of computer modeling, it was possible to find out that under such conditions exotic compounds of magnesium, silicon and oxygen begin to form (of which there should be a lot of rocky planets). For example, at pressures of more than 20 million atmospheres, not only the familiar silicon oxide SiO 2 becomes stable, but also the “impossible” SiO and SiO 3. It is also interesting that in the depths of especially massive planets (up to 20 Earth masses) MgSi 3 O 12 can be formed - an oxide with the properties of an electrical conductor. Non-standard conditions can be simulated not only on a computer, but also in the laboratory, although not for such a wide range of pressures and temperatures. Using a diamond anvil, pressures of up to 10 million atmospheres can be obtained, which exactly correspond to the conditions in the interior of planets, and the sample can be heated to high temperatures using a laser. Experiments to simulate such conditions have indeed been actively carried out recently. For example, in 2015, a group of scientists, which included Russian researchers, experimentally observed the formation of magnesium peroxide MgO 2 already at pressures of about 1.6 thousand atmospheres and temperatures of more than two thousand degrees Celsius. You can read in detail about studies of the behavior of matter at high pressures in. X-ray spectroscopy of a sample consisting of magnesium and oxygen atoms, at a pressure of about ten thousand atmospheres and a temperature of about two thousand Kelvin. The dotted line marks the area with high oxygen content. S. Lobanov et al / Scientific Reports UrFU has a group of scientists who study protoplanetary matter in deep space and the solar system. We asked Vadim Krushinsky, leading specialist at the Kourovsky Astronomical Observatory of UrFU, to talk in more detail about the study of exoplanets. N +1: Why do we study exoplanets? Vadim Krushinsky: Even 25 years ago, we knew about the existence of a single planetary system - the Solar system. Now we are sure that a huge number of stars have planets, perhaps almost every star in the Universe. The progress of technologies for obtaining and processing data has led to the fact that even an advanced amateur astronomer can find his exoplanet. The discovery of another “hot Jupiter” is the discovery of an entire planetary system, we just see only the most noticeable part of it. Planets that are smaller in size or located further from their parent star are discovered much less frequently, this is an effect of observational selection. Vadim Krushinsky, as part of a group of scientists at the Ural Federal University, is working on a project to study protoplanetary matter in deep space, the solar system and on Earth. This is one of six breakthrough scientific projects of the university, it is being carried out by the strategic academic unit (SAU) - the Institute of Natural Sciences and Mathematics of UrFU - together with academic and industrial partners from Russia and other countries. The university’s position in Russian and international rankings, primarily in subject rankings, depends on the success of researchers. A single experiment does not allow drawing conclusions about the observed phenomenon. The experiment must be repeated many times and independently. Each discovered exoplanet system is a separate independent experiment. And the more of them are known, the more reliably the general laws of the origin and evolution of planetary systems can be traced. We need to collect statistics! What can you learn about exoplanets by observing them from such great distances? First of all, we need to determine the properties of the parent star. This allows one to calculate the sizes of planets, their masses and orbital radii. Knowing the luminosity of the parent star and the radius of the orbit, one can estimate the surface temperature of the exoplanet. In addition, the atmospheres of planets have different transparency in different spectral ranges (Lomonosov wrote about this). To an observer, this looks like a different diameter of the planet when observed in different filters. This makes it possible to detect the atmosphere and estimate its thickness and density. The light from the parent star passing through the planet's atmosphere during transit carries information about the composition of its atmosphere. And during a secondary eclipse, when the planet hides behind its star, we can observe changes in the spectrum associated with reflection from the atmosphere and surface of the planet. Just like the Moon, phases can be observed in exoplanets. If the changes in the system's brightness caused by this effect are not constant, then this suggests that the planet's albedo (ability to reflect light) is changing. For example, due to the movement of clouds in its atmosphere. The properties of exoplanets must be related to the properties of their parent clouds. By studying matter at the stage of star formation, we contribute to the understanding of the evolution of planetary systems. Unfortunately, the Earth has undergone significant changes in the course of history, and no longer resembles the protoplanetary substance from which it was once born. But meteorites and comets are flying very close to us. Some of them even fall to Earth and end up in laboratories. Some of them can be reached by spacecraft. We have an excellent research object right in front of us! It remains only to prove that other planetary systems have evolved in the same way as ours. Is it possible to find life on other planets? To do this, you need to detect biomarkers - manifestations of the vital activity of organisms. The best biomarker would be the broadcasts of the conditional “Channel One”, but the presence of oxygen will do. Without life, oxygen on Earth would be bound and disappear from the atmosphere within tens of thousands of years. Having discovered oxygen in the atmospheres of exoplanets, we can say that we are not alone in the Universe. How to find it was described above. But there are no devices with sufficient sensitivity yet. A breakthrough in this direction is expected after the launch of the space telescope. James Webb (JWST). What can scientists from Russia and, in particular, from UrFU do in this area? Despite the fact that Russia lags behind the rest of the scientific community in terms of studying exoplanets, we have the opportunity to close this gap. Relatively low-budget programs for searching for exoplanetary systems (pilot project KPS at the Kourovo Observatory of UrFU) will allow you to take the first step and help in collecting data for statistical analysis. High-precision photometric measurements can be carried out using existing equipment, this makes it possible to search for the atmospheres of some exoplanets. Spectral observations during transits and secondary eclipses are relatively accessible for the largest telescopes in Russia. What you need to do to start these programs is to find interested people and pay for their work. Invest a little in equipment. The second direction is modeling and interpretation of observed effects. This can be both theoretical work and experimental work - a study of the behavior and properties of samples in space conditions and comparison with observed effects. To do this, it is necessary to create an installation that simulates the conditions of outer space. Meteorites from the UrFU collection can be used as samples. Dmitry Trunin There is nothing in the terrestrial environment around us that even remotely resembles the super-rarefied interstellar medium. Air is usually considered the lightest substance. However, compared to any interstellar nebula, the air appears to be an unusually dense formation. A cubic centimeter of room air has a mass close to one milligram; the mass of the Orion Nebula in the same volume is 100,000,000,000,000,000 (10 17) times less. This number is not easy to read. But it is even more difficult to visualize such a great degree of rarefaction of matter. The density of interstellar gas nebulae (10-20 g/cm3) is so negligible that a gas cloud with a volume of 100 cubic kilometers would have a mass of one milligram! In technology, in some cases, they strive to obtain a vacuum - a very rarefied state of gases. Using rather complex tricks, it is possible to reduce the density of room air by 10 billion times. But even such a “technical void” still turns out to be a million times denser than any gas nebula! There are so many molecules in room air that they constantly have to collide with each other. None of them can fly more than a thousandth of a centimeter without colliding with one of their neighbors. There is much more space in gaseous nebulae. Each atom can safely fly millions of kilometers here without fear of colliding with another atom. Not only on Earth, but also within the solar system, we do not know any formations that, in their rarefaction, could compete with gaseous nebulae. Even comets appear next to nebulae as dense as steel compared to air. The density of gases in the heads of comets is thousands of times greater than the density of interstellar nebulae. It may seem strange why such a rarefied medium in photographs appears to be a continuous and even dense luminous cloud, while the air is so transparent that it almost does not distort the picture of the Universe observed through it. The reason is, of course, the size of the nebulae. They are so grandiose that it is no easier to imagine the volume they occupy than their insignificant density. On average, nebulae have diameters measured in light years or even tens of light years. This means that if the Earth were reduced to the size of a pinhead, then at that scale the Orion Nebula would appear as a cloud the size of the globe! Therefore, despite the insignificant density of the gases that make it up, the substance of the Orion Nebula would still be quite enough to “manufacture” several hundred stars like our Sun. We are at a distance from the Orion Nebula that light takes 1,800 years to travel. Thanks to this, we see it all as a whole. If in the future, during interstellar flights, travelers find themselves inside the Orion Nebula, then it will not be easy to notice - this wonderful nebula viewed “from the inside” will seem almost perfectly transparent. The glow of gas nebulae can be caused by various reasons. In cases where the star adjacent to the nebula is very hot (with a surface temperature greater than 20,000 K), the atoms of the nebula re-radiate the energy received from the star, and the glow process has the character of luminescence. On the other hand, constantly moving gas clouds sometimes collide with each other and the collision energy is partially converted into radiation. Of course, these reasons can also act together. No matter how ephemeral gas nebulae are in their density, the interstellar medium is ten thousand times more rarefied. Agree that the name “visible nothingness” is much more suitable for the interstellar gaseous medium than for comets. The prevalence of elements in space is studied by cosmochemistry. Studying the abundance of elements in space is a rather difficult task, since matter in outer space is in different states (stars, planets, dust clouds, interstellar space, etc.). Sometimes the state of a substance is difficult to imagine. For example, it is difficult to talk about the state of matter and elements in neutron stars, white dwarfs, and black holes at colossal temperatures and pressures. Nevertheless, science knows quite a lot about what elements and in what quantities are present in space. In interstellar space there are ions and atoms of various elements, as well as groups of atoms, radicals and even molecules, for example molecules of formaldehyde, water, HCN, CH3CN, CO, SiO2, CoS, etc. There are especially many calcium ions in interstellar space. In addition to it, atoms of hydrogen, potassium, carbon, sodium ions, oxygen, titanium and other particles are scattered in space. The first place in abundance in the Universe belongs to hydrogen. The chemical composition of stars depends on many factors, including temperature. As the temperature increases, the composition of particles existing in the star's atmosphere becomes simpler. Thus, spectral analysis of stars with temperatures of 10,000-50,000 ° C shows lines of ionized hydrogen and helium and metal ions in their atmospheres. Radicals are already found in the atmospheres of stars with a temperature of 5000° C, and even oxide molecules are found in the atmospheres of stars with a temperature of 3800° C. The chemical composition of some stars with temperatures of 20,000-30,000 ° C is given in Table. 1.1. It can be seen that, for example, in the y-Pegasus star, for 8700 hydrogen atoms there are 1290 helium atoms, 0.9 nitrogen atoms, etc. The spectra of stars of the first 4 classes (the hottest) are dominated by lines of hydrogen and helium, but as the temperature decreases, lines of other elements and even lines of compounds appear. These are also simple compounds: oxides of zirconium, titanium, as well as radicals CH, OH, NH, CH2, C2, C3, CaH, etc. The outer layers of stars consist mainly of hydrogen. On average, for every 1,0000 hydrogen atoms there are about 1,000 helium atoms, 5 oxygen atoms and less than 1 atom of other elements. There are stars with a high content of one or another element: silicon, iron, manganese, carbon, etc. Stars with an anomalous composition are quite diverse. Young red giant stars contain increased amounts of heavy elements. Thus, one of these stars contains 26 times more molybdenum than the Sun. The chemical composition of a star reflects the influence of two factors: the nature of the interstellar medium and those nuclear reactions that develop in the star during its life. The initial composition of the star is close to the composition of the interstellar matter (cloud of gas and dust) from which the star arose. And the composition of the gas and dust clouds is not the same, which could lead to differences in the composition of the elements contained in the star. Spectral analysis shows that the presence of many elements in the composition of stars can only be caused by nuclear reactions occurring in them (barium, zirconium, technetium). There are stars in which hydrogen has turned into helium. Their atmosphere consists of helium. IN Chemical composition of some class B stars Relative number of atoms in a star t Scorpio Oxygen Aluminum Carbon, neon, titanium, nitrogen, oxygen, silicon, and magnesium have been discovered in such helium stars. Helium stars are known that contain practically no hydrogen, which burned up as a result of nuclear reactions. Carbon stars are very interesting. These are relatively cool stars (giants and supergiants), their surface temperatures range from 2500-6000 ° C. At temperatures below 3500 ° C, with equal amounts of oxygen and carbon in the atmosphere, most of these elements are bound into carbon monoxide CO. Among other carbon compounds, CN and CH radicals are present in the atmospheres of such stars. A study of the abundance of elements in space showed that as the atomic mass of an element increases, its abundance decreases. In addition, elements with even ordinal numbers are more common than those with odd numbers. The abundance of elements in space is shown in Fig. 3.1. Logarithm of relative abundance (per 1012 H atoms) Rice. 3.1. Prevalence of elements in space
Plan:
Introduction;
Bibliography.
Chemistry of the Earth;
Chemical composition of meteorites;
Chemical composition of stars;
Chemistry of interstellar space;
Beginning of lunar chemistry;
Chemical composition of planets;
If you like to look at the starry sky,
Space chemistry sounds funny, but chemistry is directly related to many human achievements in space exploration.
Without the efforts of numerous chemists, technologists, and chemical engineers, amazing structural materials that allow spacecraft to overcome gravity, super-powerful fuel that helps engines develop the necessary power, and the most precise instruments, instruments and devices that ensure the operation of space orbital stations would not have been created. .
Total - 98.59%
2. Chemical composition of meteorites.
The most precise chemical analyzes of a huge number of meteorites that fell on our planet have yielded remarkable results. It turned out that if we calculate the average content of the most common elements on Earth in all meteorites: iron, oxygen, silicon, magnesium, aluminum, calcium, then their share falls exactly 94%, i.e. there are the same amount of them in meteorites how much is in the composition of the globe. 
In addition, it turned out that in iron meteorites
. That is, both on Earth and in meteorites these elements are found in approximately the same proportions. These and many other discovered coincidences gave scientists reason to conclude: the matter on Earth and the matter in celestial space are the same. It consists of the same elements.
Element
Quantity (approx.)
Hydrogen
8300
Helium
1700
Carbon
1,5
Nitrogen
0,9
Oxygen
9,0
Fluorine
0,028
Neon
3,4
Magnesium
0,49
Aluminum
0,05
Silicon
0,77
Phosphorus
0,0028
Sulfur
0,25
Chlorine
0,014
Argon
0,07
This table shows only approximate numbers, but there are stars that have a high content of one or another element. Thus, there are known stars with a high content of silicon (silicon stars), stars in which there is a lot of iron (iron stars), manganese (manganese), carbon (carbon stars), etc. Stars with an anomalous composition of elements are quite diverse. Increased abundances of heavy elements have been discovered in young red giant stars. In one of them, an increased content of molybdenum was found, 26 times higher than its content in the Sun.
Probably, in all stars accessible to our observation, hydrogen predominates, but the content of other elements of the stars varies greatly: in some stars such a high content of individual elements was found compared to ordinary stars that they are even called in astrophysics: “magnesium”, “ silicon", "iron", "strontium", "carbon" stars. Even “lithium” and “phosphorus” stars have recently been discovered. These mysterious differences in stellar compositions still await explanation.
4. Chemistry of interstellar space.
5. The beginning of lunar chemistry.
Many years ago, in 1609, Galileo Galilei first pointed a telescope into the sky. The lunar “seas” appeared to him framed by shores of white stone. After Galileo’s observations, it was believed for a long time that the lunar “seas” were filled with water. They even said that it was more pleasant to live on the Moon than on Earth. Famous astronomer of the 18th century. William Herschel wrote: “As for me, if I had to choose whether to live on the Earth or the Moon, I would not hesitate for a moment to choose the Moon.”
and the Moon does not have long linear ridges like the Earth. Ring structures rise there - high (up to several kilometers) walls of huge volcanic circuses - craters. Large craters, several kilometers in diameter, trace their origins to volcanoes. Their lava, pouring into low places, formed colossal lava lakes - these are the lunar “seas”. Many craters less than a kilometer in diameter were probably created by the fall of meteorites or rocks raised by explosive volcanism on the Moon. This assumption was confirmed in 1972. A meteorite fell on the Moon and formed a new crater with a diameter of 100 m. The meteorite activated seismic instruments installed on the Moon. This makes it possible to determine the thickness of the lunar crust and learn about its deep structure.
Thus, the lunar “seas” are composed of basaltic lava and covered with fine-grained soil of the same composition. But in detail, one “sea” differs from another. The Sea of Plenty, for example, consists of basalts with about 3% titanium, and the basalts of the Sea of Tranquility contain up to 10% titanium. It is found here in the form of the mineral ilmenite. Marine lunar basalts are rich in iron - up to 18%, while in terrestrial basalts it is usually about 7%. Compared to terrestrial basalts, lunar basalts have a higher content of uranium, thorium and potassium. These radioactive elements cause lunar volcanism.
knowledge about planetary chemistry is growing very quickly. In recent years, we have learned a lot about the laws of chemical transformations of matter and its composition on mysterious distant worlds - our neighbors in the Universe.
Reliable information has now been obtained about the chemical composition of its atmosphere and the conditions on its surface.
Soviet and American scientists sent automatic research stations to Mars. Even though separated by tens of millions of miles of empty space, Mars and Earth share a mysterious connection. It has been established that the atmosphere of this planet consists almost of carbon dioxide, with some nitrogen, oxygen and water vapor. The atmosphere of Mars is very rarefied, its surface pressure is more than 100 times less than on Earth. Temperatures below 0 o C prevail on Mars; huge daily temperature fluctuations cause terrible dust storms. The surface of the planet, like the Moon, is covered with many craters. Mars is a cold, lifeless, dusty desert.
Scientists have calculated that Jupiter's inner core must be very hot. It receives little heat from the Sun - 27 times less than the Earth, and at the same time reflects 40% back into space. But it emits four times more than it absorbs. Where Jupiter gets the extra energy from and how it arises is unknown. Thermonuclear processes are impossible on it. Perhaps this excess energy is the energy of the planet’s compression?
blue color Uranus is the result of absorption of red light by methane in the upper atmosphere. Clouds of other colors probably exist, but they are hidden from observers by an overlying layer of methane. The atmosphere of Uranus (but not Uranus as a whole!) consists of approximately 83% hydrogen, 15% helium and 2% methane. Like other gas planets, Uranus has bands of clouds that move very quickly. But they are too poorly distinguishable and are visible only in high-resolution images taken by Voyager 2. Recent observations from HST have revealed large clouds. There is an assumption that this possibility appeared in connection with seasonal effects, because as you might imagine, winter and summer on Uranus differ greatly: the entire hemisphere hides from the Sun for several years in winter! However, Uranus receives 370 times less heat from the Sun than Earth, so it doesn't get hot there in the summer either. In addition, Uranus emits no more heat than it receives from the Sun, therefore, it is most likely cold inside
triplication and set of components Neptune elements are probably similar to Uranus: various "ices" or solidified gases containing about 15% hydrogen and a small amount of helium Like Uranus, and unlike Jupiter and Saturn, Neptune may not have a clear internal stratification. But most likely, it has a small solid core (equal in mass to the Earth). Neptune's atmosphere is mostly methane: Neptune's blue color results from the absorption of red light in the atmosphere by this gas, as on Uranus. Like a typical gas planet, Neptune is famous for large storms and eddies, fast winds blowing in limited bands parallel to the equator. Neptune has the fastest winds in the solar system, reaching speeds of up to 2,200 km/h. The winds blow on Neptune in a westerly direction, against the planet's rotation. Note that for giant planets, the speed of flows and currents in their atmospheres increases with distance from the Sun. This pattern has no explanation yet. In the pictures you see clouds in Neptune's atmosphere. Like Jupiter and Saturn, Neptune has an internal heat source - it emits more than two and a half times more energy than it receives from the Sun.
Saturn's atmosphere is mainly hydrogen and helium. But due to the peculiarity of the formation of the planet, part of Saturn is larger than on Jupiter and consists of other substances. Voyager 1 found that about 7 percent of the volume of Saturn's upper atmosphere is helium (compared with 11 percent in Jupiter's atmosphere), while almost everything else is hydrogen.Rainbow in the service of astronomers
What can you find in space
A little closer to the planets
"Impossible" connections
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