Mendeleev's thoughts on the structure of the atom. Mendeleev

(1834-1907) - a great Russian scientist, famous for his work in the fields of chemistry, physics, geology, economics and meteorology. Also an excellent teacher and popularizer of science, a member of a number of European academies of sciences, one of the founders of the Russian Physical and Chemical Society. In 1984, the United Nations Educational, Scientific and Cultural Organization (UNESCO) named Mendeleev the greatest scientist of all time.

Personal data

D.I. Mendeleev was born in the Siberian city of Tobolsk in 1834 in the family of the director of the gymnasium Ivan Pavlovich Mendeleev and his wife Maria Dmitrievna. He was their last, seventeenth child.

At the gymnasium, Dmitry did not study very well, he had low grades in all subjects, Latin was especially difficult for him. After the death of his father, the family moved to St. Petersburg.

In the capital, Dmitry entered the Pedagogical Institute, from which he graduated in 1855 with a gold medal. Almost immediately after graduating from the institute, Mendeleev fell ill with pulmonary tuberculosis. The doctors' prognosis was disappointing, and he hastily went to Simferopol, where the famous surgeon N.I. worked at that time. Pirogov .

When Pirogov examined Dmitry, he made an optimistic diagnosis: he said that the patient would live for a very long time. The great doctor turned out to be right - Mendeleev soon fully recovered. Dmitry returned to the capital to continue his scientific work, and in 1856 he defended his master's thesis at St. Petersburg University.

Work history

Having become a master, Dmitry received the position of private assistant professor and began giving a course of lectures on organic chemistry. His talent as a teacher and scientist was highly appreciated by his leadership, and in 1859 he was sent on a two-year scientific trip to Germany. Returning to Russia, he continued lecturing and soon discovered that students lacked good textbooks. And so in 1861, Mendeleev himself published a textbook - “Organic Chemistry”, which was soon awarded the Demidov Prize by the St. Petersburg Academy of Sciences. In 1864, Mendeleev was elected professor of chemistry at the Technological Institute. And the following year he defended his doctoral dissertation “On the combination of alcohol with water.” Two years later, he already headed the department of inorganic chemistry at the university. Here Dmitry Ivanovich begins to write his great work - “Fundamentals of Chemistry”.

In 1869, he published a table of the elements entitled “An Essay on a System of Elements Based on Their Atomic Weight and Chemical Similarity.” He compiled his table based on the Periodic Law he discovered. During Dmitry Ivanovich’s lifetime, “Fundamentals of Chemistry” was republished 8 times in Russia and 5 times abroad, in English, German and French. In 1874, Mendeleev derived the general equation of state of an ideal gas, including, in particular, the dependence of the gas state on temperature, discovered in 1834 by the physicist B.P.E. Clapeyron (Clapeyron - Mendeleev equation).

Mendeleev also suggested the existence of a number of elements unknown at that time. His ideas were confirmed, as documented. The great scientist was able to accurately predict the chemical properties of gallium, scandium and germanium.

In 1890, Mendeleev left St. Petersburg University due to a conflict with the Minister of Education, who, during student unrest, refused to accept a student petition from Mendeleev. After leaving the university, Dmitry Ivanovich in the period 1890-1892. took part in the development of smokeless gunpowder. Since 1892, Dmitry Ivanovich Mendeleev has been the scientist-custodian of the “Depot of Exemplary Weights and Scales,” which in 1893, on his initiative, was transformed into the Main Chamber of Weights and Measures (now the All-Russian Research Institute of Metrology named after D.I. Mendeleev). In his new field, Mendeleev achieved good results, creating the most accurate weighing methods for that time. By the way, the name of Mendeleev is often associated with the choice of vodka with a strength of 40°.

Mendeleev developed a new technology for oil refining, was involved in the chemicalization of agriculture, and created a device (pycnometer) for determining the density of liquids. In 1903, he was the first State Admissions Committee of the Kyiv Polytechnic Institute.

In addition to science, Mendeleev was well versed in economics. He once joked: “What kind of chemist I am, I am a political economist. What about “Fundamentals of Chemistry”, but “Sensible Tariff” is another matter.” It was he who proposed a system of protectionist measures to strengthen the economy of the Russian Empire. He consistently defended the need to protect Russian industry from competition from Western countries, linking the development of Russian industry with customs policy. The scientist noted the injustice of the economic order, which allows countries processing raw materials to reap the fruits of the labor of workers in countries that supply raw materials.

Mendeleev also developed a scientific basis for promising ways of economic development. Shortly before his death, in 1906, Mendeleev published his book “Towards an Understanding of Russia,” in which he summarized his views on the prospects for the country’s development.

Information about relatives

Dmitry Ivanovich Mendeleev's father, Ivan Pavlovich Mendeleev, came from a priest's family and himself studied at a theological school.

Mother - Maria Dmitrievna, came from an old but impoverished merchant family of the Kornilievs.

Dmitry Ivanovich's son from his first marriage, Vladimir (1865-1898), chose a naval career. He graduated with honors from the Naval Cadet Corps, sailed on the frigate “Memory of Azov” around Asia and along the Far Eastern shores of the Pacific Ocean (1890-1893). He also took part in the entry of the Russian squadron into France. In 1898, he retired and began to develop the “Project for raising the level of the Sea of ​​Azov by damming the Kerch Strait.” His work clearly demonstrated the talent of a hydrological engineer, but Mendeleev’s son was not destined to achieve major scientific successes - he died suddenly on December 19, 1898.

Olga is the sister of Vladimir (1868-1950), graduated from high school and married Alexei Vladimirovich Trirogov, who studied with her brother in the Naval Cadet Corps. She devoted almost her entire long life to her family. Olga wrote a book of memoirs, “Mendeleev and His Family,” which was published in 1947.

In his second marriage, Mendeleev had four children: Lyubov, Ivan and twins Maria and Vasily.

Of all the descendants of Dmitry Ivanovich, Lyuba turned out to be a person who became known to a wide circle of people. And first of all, not as the daughter of a great scientist, but as a wife Alexandra Blok- the famous Russian poet of the Silver Age and as the heroine of his cycle “Poems to a Beautiful Lady”.

Lyuba graduated from the “Higher Women's Courses” and for some time was interested in theatrical art. In 1907-1908 she played in the troupe of V.E. Meyerhold and in the Theater of V.F. Komissarzhevskaya. The Bloks' married life was chaotic and difficult, and Alexander and Lyubov are equally to blame for this. However, in the last years of the poet’s life, his wife always remained by his side. By the way, she became the first public performer of the poem “The Twelve.” After Blok’s death, Lyubov studied the history and theory of ballet art, studied the teaching school of Agrippina Vaganova and gave acting lessons to the famous ballerinas Galina Kirillova and Natalya Dudinskaya. Lyubov Dmitrievna died in 1939.

Ivan Dmitrievich (1883-1936) graduated from the gymnasium in 1901 with a gold medal, entered the St. Petersburg Polytechnic Institute, but soon transferred to the university’s Faculty of Physics and Mathematics. He helped his father a lot, performing complex calculations for his economic works. Thanks to Ivan, the posthumous edition of the scientist’s work “Addition to the Knowledge of Russia” was published. After the death of Dmitry Ivanovich, his son’s life changed dramatically. He lived in France for several years, then settled on the Mendeleev estate Boblovo, organizing a school there for peasant children.

From 1924 until his death, Ivan worked in the “Main Chamber of Weights and Measures,” continuing the work of his father, who published a number of works in the field of the theory of weights and measures. Here he conducted research on the theory of scales and the design of thermostats. He was one of the first in the USSR to study the properties of “heavy water”. From a young age, Ivan studied philosophy. He outlined his ideas in the books “Thoughts on Knowledge” and “Justification of Truth,” which were published in 1909-1910. In addition, Ivan wrote memoirs about his father. They were published in full only in 1993. One of the scientist’s biographers, Mikhail Nikolaevich Mladentsev, wrote that between the son and father “there was a rare friendly relationship. Dmitry Ivanovich noted his son’s natural talents and in his person he had a friend, an adviser, with whom he shared ideas and thoughts.”

Little information has been preserved about Vasily. It is known that he graduated from the Marine Technical School in Kronstadt. He had a knack for technical creativity and developed a model of a super-heavy tank. After the revolution, fate brought him to Kuban, to Ekaterinodar, where he died of typhus in 1922.

Maria studied at the “Higher Women's Agricultural Courses” in St. Petersburg, then for a long time she taught at technical schools. After the Great Patriotic War, she became the head of the D.I. Mendeleev Museum-Archive at Leningrad University. A year before Maria Dmitrievna’s death, the first collection of archival information about Mendeleev, on which she worked, was published - “The Archive of D.I. Mendeleev” (1951).

Personal life

In 1857, Dmitry Mendeleev proposes to Sofya Kash, whom he knew back in Tobolsk, gives her an engagement ring, and seriously prepares for marriage to the girl he loves very much. But unexpectedly, Sophia returned the wedding ring to him and said that there would be no wedding. Mendeleev was shocked by this news, fell ill and did not get out of bed for a long time. His sister Olga Ivanovna decided to help her brother organize his personal life and insisted on his engagement to Feozva Nikitichnaya Leshcheva (1828-1906), whom Mendeleev knew back in Tobolsk. Feozva, the adopted daughter of Mendeleev’s teacher, poet Pyotr Petrovich Ershov, author of the famous “The Little Humpbacked Horse,” was six years older than the groom. On April 29, 1862 they got married.

In this marriage three children were born: daughter Maria (1863) - she died in infancy, son Volodya (1865) and daughter Olga. Mendeleev loved children very much, but his relationship with his wife did not work out. She did not understand her husband at all, who was absorbed in scientific research. There were often conflicts in the family, and he felt unhappy, which he told his friends about. As a result, they separated, although they formally remained married.

At 43, Dmitry Ivanovich fell in love with 19-year-old Anna Popova, a beauty who often visited the Mendeleevs’ house. She was fond of painting, was well educated, and easily found a common language with famous people who gathered at Dmitry Ivanovich. They began a relationship, although Anna's father was categorically against this union and demanded that Mendeleev leave his daughter alone. Dmitry Ivanovich did not agree, and then Anna was sent abroad, to Italy. However, Dmitry Ivanovich followed her. A month later they returned home together and got married. This marriage turned out to be very successful. The couple got along well and understood each other perfectly. Anna Ivanovna was a good and attentive wife, living in the interests of her famous husband.

Hobbies

Dmitry Ivanovich loved painting, music, and was fond of fiction, especially novels Jules Verne. Despite his busy schedule, Dmitry Ivanovich made boxes, made suitcases and frames for portraits, and bound books. Mendeleev took his hobby very seriously, and the things he made with his own hands were of high quality. There is a story about how once Dmitry Ivanovich was buying materials for his crafts, and supposedly one seller asked another: “Who is this honorable gentleman?” The answer was quite unexpected: “Oh, this is the master of suitcases - Mendeleev!”

It is also known that Mendeleev sewed his own clothes, considering store-bought ones inconvenient.

Enemies

Mendeleev's real enemies were those who voted against his election as an academician. Despite the fact that Mendeleev was recommended for the post of academician by the great scientist A.M. Butlerov and despite the fact that Dmitry Ivanovich was already world famous and recognized as a scientific leader, the following voted against his election: Litke, Veselovsky, Helmersen, Schrenk, Maksimovich, Strauch, Schmidt, Wild, Gadolin. Here it is, a list of obvious enemies of the Russian scientist. Even Beilstein, who became an academician instead of Mendeleev by a margin of just one vote, often said: “In Russia we no longer have talents as powerful as Mendeleev.” However, the injustice was never corrected.

Companions

A close friend and ally of Mendeleev was the rector of St. Petersburg University A.N. Beketov- grandfather of Alexander Blok. Their estates were located near Klin, not far from one another. Also, Mendeleev's scientific associates were members of the St. Petersburg Academy of Sciences - Bunyakovsky, Koksharov, Butlerov, Famintsyn, Ovsyannikov, Chebyshev, Alekseev, Struve and Savi. Among the scientist's friends were great Russian artists Repin , Shishkin , Kuindzhi .

Weaknesses

Mendeleev smoked a lot, carefully selecting tobacco and rolling his own cigarettes; he never used a cigarette holder. And when friends and doctors advised him to quit, pointing to his poor health, he said that you could die without smoking. Another weakness of Dmitry Ivanovich, along with tobacco, was tea. He had his own channel for delivering tea home from Kyakhta, where it arrived in caravans from China. Mendeleev, through “scientific channels,” agreed to order tea for himself by mail directly from this city directly to his home. He ordered it for several years at once, and when the tsibiki were delivered to the apartment, the whole family began sorting and packaging the tea. The floor was covered with tablecloths, the cibiks were opened, all the tea was poured onto the tablecloth and quickly mixed. This had to be done because the tea in the cibiks lay in layers and it had to be mixed as quickly as possible so that it did not dry out. Then the tea was poured into huge glass bottles and sealed tightly. All family members took part in the ceremony, and all household members and relatives shared tea. Mendeleev's tea earned great fame among his acquaintances, and Dmitry Ivanovich himself, not recognizing any other, did not drink tea when visiting.

According to the recollections of many people who knew the great scientist closely, he was a tough, harsh and unrestrained person. Oddly enough, even being a very famous scientist, he was always nervous at demonstrations of experiments, afraid of “getting into embarrassment.”

Strengths

Mendeleev worked in various fields of science and achieved excellent results everywhere. Even a few ordinary human lives would not be enough for such a colossal expenditure of intelligence and spiritual strength. But the scientist had phenomenal performance, incredible endurance and dedication. He managed to be many years ahead of his time in many areas of science.

Throughout his life, Mendeleev made various forecasts and foresights, which almost always came true, since they were based on natural intelligence, significant knowledge and unique intuition. There are many testimonies of his relatives and friends, shocked by the genius scientist’s gift to anticipate events, to literally see the future, not only in science, but also in other areas of life. Mendeleev had excellent analytical skills, and his predictions, even related to political issues, were brilliantly confirmed. For example, he accurately predicted the beginning of the Russian-Japanese War of 1905 and the dire consequences of this war for Russia.

The students he taught loved their illustrious professor very much, but they said that he had a hard time passing exams. He did not make concessions to anyone, did not tolerate poorly prepared answers, and was intolerant of careless students.

Tough and harsh in everyday life, Mendeleev treated children very kindly and loved them incredibly tenderly.

Merits and failures

Mendeleev's services to science have long been recognized by the entire scientific world. He was a member of almost all the most authoritative academies that existed in his time and an honorary member of many scientific societies (the total number of institutions that considered Mendeleev an honorary member reached 100). His name enjoyed particular honor in England, where he was awarded the Davy, Faraday and Copylean medals, where he was invited (1888) as a Faraday lecturer, an honor that falls to only a few scientists.

In 1876, he was a corresponding member of the St. Petersburg Academy of Sciences; in 1880, he was nominated as an academician, but Beilstein, the author of an extensive reference book on organic chemistry, was accepted instead. This fact caused indignation in wide circles of Russian society. A few years later, when Mendeleev was again asked to run for the Academy, he refused.

Mendeleev is certainly an outstanding scientist, but even the greatest people make mistakes. Like many scientists of that time, he defended the erroneous concept of the existence of “ether” - a special entity that fills cosmic space and transmits light, heat and gravity. Mendeleev assumed that ether could be a specific state of gases at high rarefaction or a special gas with very low weight. In 1902, one of his most original works, “An Attempt at a Chemical Understanding of the World Ether,” was published. Mendeleev believed that “the world ether can be imagined like helium and argon, incapable of chemical compounds.” That is, from a chemical point of view, he considered ether as an element preceding hydrogen, and to place it in his table he introduced it into the zero group and zero period. The future showed that Mendeleev's concept of the chemical understanding of ether turned out to be erroneous, like all similar concepts.

It was not long before Mendeleev was able to understand the significance of such fundamental achievements as the discovery of the phenomenon of radioactivity, the electron, and subsequent results directly related to these discoveries. He complained that chemistry had become "entangled in ions and electrons." Only after visiting the Curie and Becquerel laboratories in Paris in April 1902 did Mendeleev change his point of view. Some time later, he instructed one of his subordinates in the House of Weights and Measures to conduct a study of radioactive phenomena, which, however, had no consequences due to the death of the scientist.

Compromising evidence

When Mendeleev wanted to formalize his relationship with Anna Popova, he encountered great difficulties, since official divorce and remarriage were complex processes in those years. To help the great man arrange his personal life, his friends convinced Mendeleev’s first wife to agree to a divorce. But even after her consent and subsequent divorce, Dmitry Ivanovich, according to the laws of that time, had to wait another six years before entering into a new marriage. The Church imposed a “six-year penance” on him. In order to obtain permission for a second marriage, without waiting for the expiration of the six-year period, Dmitry Ivanovich bribed the priest. The amount of the bribe was huge - 10 thousand rubles, for comparison - Mendeleev’s estate was estimated at 8 thousand.

Dmitry Ivanovich Mendeleev is a Russian scientist, a brilliant chemist, physicist, researcher in the field of metrology, hydrodynamics, geology, a deep expert in industry, instrument maker, economist, aeronaut, teacher, public figure and original thinker.

Childhood and youth

The great scientist was born in 1834, on February 8, in Tobolsk. Father Ivan Pavlovich was the director of district schools and the Tobolsk gymnasium, descended from the family of priest Pavel Maksimovich Sokolov, Russian by nationality.

Ivan changed his last name in childhood, while a student at the Tver Seminary. Presumably, this was done in honor of his godfather, the landowner Mendeleev. Later, the question of the nationality of the scientist’s surname was repeatedly raised. According to some sources, she testified to Jewish roots, according to others, to German ones. Dmitry Mendeleev himself said that his last name was assigned to Ivan by his teacher from the seminary. The young man made a successful exchange and thereby became famous among his classmates. With two words - “to do” - Ivan Pavlovich was included in the educational record.

Mother Maria Dmitrievna (nee Kornilieva) was involved in raising children and housekeeping, and had a reputation as an intelligent and smart woman. Dmitry was the youngest in the family, the last of fourteen children (according to other information, the last of seventeen children). At the age of 10, the boy lost his father, who became blind and soon died.

While studying at the gymnasium, Dmitry did not show any abilities; Latin was the most difficult for him. His mother instilled a love for science, and she also participated in the formation of his character. Maria Dmitrievna took her son to study in St. Petersburg.

In 1850, in St. Petersburg, the young man entered the Main Pedagogical Institute at the department of natural sciences, physics and mathematics. His teachers were professors E. H. Lenz, A. A. Voskresensky and N. V. Ostrogradsky.

While studying at the institute (1850-1855), Mendeleev demonstrated extraordinary abilities. As a student, he published an article “On Isomorphism” and a series of chemical analyzes.

The science

In 1855, Dmitry received a diploma with a gold medal and a referral to Simferopol. Here he works as a senior teacher at the gymnasium. With the outbreak of the Crimean War, Mendeleev moved to Odessa and received a teaching position at the Lyceum.

In 1856 he was again in St. Petersburg. He studies at the university, defends his dissertation, teaches chemistry. In the fall, he defends another dissertation and is appointed as a private assistant professor at the university.

In 1859, Mendeleev was sent on a business trip to Germany. Works at the University of Heidelberg, sets up a laboratory, studies capillary liquids. Here he wrote articles “On the temperature of absolute boiling” and “On the expansion of liquids”, and discovered the phenomenon of “critical temperature”.

In 1861, the scientist returned to St. Petersburg. He creates the textbook “Organic Chemistry”, for which he was awarded the Demidov Prize. In 1864 he was already a professor, and two years later he headed the department, teaching and working on the “Fundamentals of Chemistry.”

In 1869, he introduced the periodic system of elements, to the improvement of which he devoted his entire life. In the table, Mendeleev presented the atomic masses of nine elements, later adding a group of noble gases to the table and leaving room for elements that had yet to be discovered. In the 90s, Dmitry Mendeleev contributed to the discovery of the phenomenon of radioactivity. The periodic law included evidence of the connection between the properties of elements and their atomic volume. Now next to each table of chemical elements there is a photo of the discoverer.

In 1865–1887 he developed the hydration theory of solutions. In 1872 he began to study the elasticity of gases, and two years later he derived the ideal gas equation. Among Mendeleev's achievements of this period was the creation of a scheme for fractional distillation of petroleum products, the use of tanks and pipelines. With the assistance of Dmitry Ivanovich, the burning of black gold in furnaces completely stopped. The scientist’s phrase “Burning oil is like burning a stove with banknotes” has become an aphorism.

Another area of ​​activity of the scientist was geographical research. In 1875, Dmitry Ivanovich attended the Paris International Geographical Congress, where he presented his invention - a differential barometer-altimeter. In 1887, the scientist took part in a balloon trip into the upper atmosphere to observe a total solar eclipse.

In 1890, a quarrel with a high-ranking official caused Mendeleev to leave the university. In 1892, a chemist invents a method for producing smokeless gunpowder. At the same time, he is appointed keeper of the Depot of Exemplary Weights and Measures. Here he renews the prototypes of the pound and arshin, and makes calculations comparing Russian and English standards of measures.

On the initiative of Mendeleev, in 1899 the metric system of measures was optionally introduced. In 1905, 1906 and 1907, the scientist was nominated as a candidate for the Nobel Prize. In 1906, the Nobel Committee awarded the prize to Mendeleev, but the Royal Swedish Academy of Sciences did not confirm this decision.

Mendeleev, who was the author of more than one and a half thousand works, had enormous scientific authority in the world. For his services, the scientist was awarded numerous scientific titles, Russian and foreign awards, and was an honorary member of a number of scientific societies at home and abroad.

Personal life

In his youth, an unpleasant incident happened to Dmitry. His courtship with the girl Sonya, whom he had known since childhood, ended in an engagement. But the pampered beauty never went to the crown. On the eve of the wedding, when preparations were already in full swing, Sonechka refused to get married. The girl thought that there was no point in changing anything if life was already good.

Dmitry was painfully worried about the breakup with his fiancée, but life went on as usual. He was distracted from his heavy thoughts by a trip abroad, lecturing and loyal friends. Having renewed his relationship with Feozva Nikitichnaya Leshcheva, whom he had known previously, he began dating her. The girl was 6 years older than Dmitry, but looked young, so the age difference was unnoticeable.

In 1862 they became husband and wife. The first daughter Masha was born in 1863, but lived only a few months. In 1865, a son, Volodya, was born, and three years later, a daughter, Olya. Dmitry Ivanovich was attached to children, but devoted little time to them, since his life was devoted to scientific activity. In a marriage concluded on the principle of “endure and fall in love,” he was not happy.

In 1877, Dmitry met Anna Ivanovna Popova, who became for him a person capable of supporting him with a smart word in difficult times. The girl turned out to be a creatively gifted person: she studied piano at the conservatory, and later at the Academy of Arts.

Dmitry Ivanovich hosted youth “Fridays”, where he met Anna. “Fridays” were transformed into literary and artistic “environments”, the regulars of which were talented artists and professors. Among them were Nikolai Wagner, Nikolai Beketov and others.

The marriage of Dmitry and Anna took place in 1881. Soon their daughter Lyuba was born, son Ivan appeared in 1883, twins Vasily and Maria - in 1886. In his second marriage, the scientist’s personal life was happy. Later, the poet became Dmitry Ivanovich's son-in-law, having married the daughter of the scientist Lyubov.

Death

At the beginning of 1907, a meeting between Dmitry Mendeleev and the new Minister of Industry Dmitry Filosofov took place in the Chamber of Weights and Measures. After touring the ward, the scientist fell ill with a cold, which caused pneumonia. But even being very ill, Dmitry continued to work on the manuscript “Towards the Knowledge of Russia”, the last words he wrote in which were the phrase:

“In conclusion, I consider it necessary, at least in the most general terms, to express...”

Death occurred at five o'clock in the morning on February 2 due to cardiac paralysis. The grave of Dmitry Mendeleev is located at the Volkov cemetery in St. Petersburg.

The memory of Dmitry Mendeleev is immortalized by a number of monuments, documentaries, and the book “Dmitry Mendeleev. The author of the great law."

• Many interesting biographical facts are associated with the name of Dmitry Mendeleev. In addition to his activities as a scientist, Dmitry Ivanovich was engaged in industrial exploration. In the 70s, the oil industry began to flourish in the United States, and technologies appeared that made the production of petroleum products cheaper. Russian manufacturers began to suffer losses in the international market due to their inability to compete on price.
• In 1876, at the request of the Russian Ministry of Finance and the Russian Technical Society, which collaborated with the military department, Mendeleev went overseas to an exhibition of technical innovations. On site, the chemist learned innovative principles for making kerosene and other petroleum products. And using ordered reports from European railway services, Dmitry Ivanovich tried to decipher the method of making smokeless gunpowder, which he succeeded in.

• Mendeleev had a hobby - making suitcases. The scientist sewed his own clothes.
• The scientist is credited with the invention of vodka and the moonshine still. But in fact, Dmitry Ivanovich, in the topic of his doctoral dissertation “Discourse on the combination of alcohol with water,” studied the issue of reducing the volume of mixed liquids. There was not a word about vodka in the scientist’s work. And the standard of 40° was established in Tsarist Russia back in 1843.
• He came up with pressurized compartments for passengers and pilots.
• There is a legend that the discovery of Mendeleev’s periodic system happened in a dream, but this is a myth created by the scientist himself.
• He rolled his own cigarettes using expensive tobacco. He said that he would never quit smoking.

Discoveries

• He created a controlled balloon, which became an invaluable contribution to aeronautics.
• He developed a periodic table of chemical elements, which became a graphic expression of the law established by Mendeleev during his work on the “Fundamentals of Chemistry”.
• He created a pycnometer, a device capable of determining the density of a liquid.
• Discovered the critical boiling point of liquids.
• Created an equation of state for an ideal gas, establishing the relationship between the absolute temperature of an ideal gas, pressure and molar volume.
• He opened the Main Chamber of Weights and Measures - the central institution of the Ministry of Finance, which was in charge of the verification department of the Russian Empire, subordinate to the trade department.

The periodic law and the periodic system of chemical elements of D. I. Mendeleev based on ideas about the structure of the atom.

1. formulation of the periodic law

D.I. Mendeleev in the light of the theory of atomic structure.

The discovery of the periodic law and the development of the periodic system of chemical elements by D. I. Mendeleev were the pinnacle of the development of chemistry in the 19th century. A vast amount of knowledge about the properties of 63 elements known at that time was brought into order.

D.I. Mendeleev believed that the main characteristic of elements is their atomic weights, and in 1869 he first formulated the periodic law.

The properties of simple bodies, as well as the forms and properties of compounds of elements, are periodically dependent on the atomic weights of the elements.

Mendeleev divided the entire series of elements, arranged in order of increasing atomic masses, into periods, within which the properties of the elements change sequentially, placing the periods so as to highlight similar elements.

However, despite the enormous significance of such a conclusion, the periodic law and Mendeleev’s system represented only a brilliant generalization of facts, and their physical meaning remained unclear for a long time. Only as a result of the development of physics of the 20th century - the discovery of the electron, radioactivity, the development of the theory of atomic structure - the young, talented English physicist G. Mosle established that the magnitude of the charges of atomic nuclei consistently increases from element to element by one. With this discovery, Mosle confirmed the brilliant guess of Mendeleev, who in three places of the periodic table moved away from the increasing sequence of atomic weights.

Thus, when compiling it, Mendeleev placed 27 Co in front of 28 Ni, 52 Ti in front of 5 J, 18 Ar in front of 19 K, despite the fact that this contradicted the formulation of the periodic law, that is, the arrangement of elements in order of increasing atomic weights.

According to Mosle's law, the charges of nuclei of these elements corresponded to their position in the table.

In connection with the discovery of Mosle's law, the modern formulation of the periodic law is as follows:

the properties of elements, as well as the forms and properties of their compounds, are periodically dependent on the charge of the nucleus of their atoms.

The connection between the periodic law and the periodic system and the structure of atoms.

So, the main characteristic of an atom is not the atomic mass, but the magnitude of the positive charge of the nucleus. This is a more general accurate characteristic of an atom, and therefore an element. All properties of the Element and its position in the periodic table depend on the magnitude of the positive charge of the atomic nucleus. Thus, The serial number of a chemical element numerically coincides with the charge of the nucleus of its atom. The periodic table of elements is a graphic representation of the periodic law and reflects the structure of the atoms of the elements.

The theory of atomic structure explains the periodic changes in the properties of elements. An increase in the positive charge of atomic nuclei from 1 to 110 leads to a periodic repetition of the structural elements of the external energy level in atoms. And since the properties of elements mainly depend on the number of electrons at the outer level; then they repeat periodically. This is the physical meaning of the periodic law.

As an example, consider the change in properties of the first and last elements of periods. Each period in the periodic system begins with elements of atoms, which at the outer level have one s-electron (incomplete outer levels) and therefore exhibit similar properties - they easily give up valence electrons, which determines their metallic character. These are alkali metals - Li, Na, K, Rb, Cs.

The period ends with elements whose atoms at the outer level contain 2 (s 2) electrons (in the first period) or 8 (s 1 p 6) electrons (in all subsequent ones), that is, they have a completed external level. These are noble gases He, Ne, Ar, Kr, Xe, which have inert properties.

It is precisely because of the similarity in the structure of the external energy level that their physical and chemical properties are similar.

In each period, with an increase in the ordinal number of the elements, the metallic properties gradually weaken and non-metallic properties increase, and the period ends with an inert gas. In each period, with an increase in the ordinal number of the elements, the metallic properties gradually weaken and non-metallic properties increase, and the period ends with an inert gas.

In the light of the doctrine of the structure of the atom, the division of all elements into seven periods made by D. I. Mendeleev becomes clear. The period number corresponds to the number of energy levels of the atom, that is, the position of elements in the periodic table is determined by the structure of their atoms. Depending on which sublevel is filled with electrons, all elements are divided into four types.

1. s-elements. The s-sublayer of the outer layer (s 1 - s 2) is filled. This includes the first two elements of each period.

2. p-elements. The p-sublevel of the external level is filled (p 1 -- p 6) - This includes the last six elements of each period, starting from the second.

3. d-elements. The d-sublevel of the last level (d1 - d 10) is filled, and 1 or 2 electrons remain at the last (outer) level. These include elements of plug-in decades (10) of large periods, starting from the 4th, located between the s- and p-elements (they are also called transition elements).

4. f-elements. The f-sublevel of the deep (one third of it outside) level is filled (f 1 -f 14), and the structure of the external electronic level remains unchanged. These are lanthanides and actinides, located in the sixth and seventh periods.

Thus, the number of elements in periods (2-8-18-32) corresponds to the maximum possible number of electrons at the corresponding energy levels: in the first - two, in the second - eight, in the third - eighteen, and in the fourth - thirty-two electrons. The division of groups into subgroups (main and secondary) is based on the difference in the filling of energy levels with electrons. The main subgroup consists s- and p-elements, and a secondary subgroup - d-elements. Each group combines elements whose atoms have a similar structure of the external energy level. In this case, the atoms of the elements of the main subgroups contain at the outer (last) levels a number of electrons equal to the group number. These are the so-called valence electrons.

For elements of side subgroups, the valence electrons are not only the outer ones, but also the penultimate (second outer) levels, which is the main difference in the properties of the elements of the main and side subgroups.

It follows that the group number usually indicates the number of electrons that can participate in the formation of chemical bonds. This is physical meaning of the group number.

From the standpoint of the theory of atomic structure, the increase in the metallic properties of elements in each group with increasing charge of the atomic nucleus is easily explained. Comparing, for example, the distribution of electrons by levels in atoms 9 F (1s 2 2s 2 2р 5) and 53J (1s 2 2s 2 2р 6 3s 2 Зр 6 3d 10 4s 2 4 p 6 4d 10 5s 2 5p 5) it can be noted that they have 7 electrons in the outer level, which indicates similar properties. However, the outer electrons in an iodine atom are further away from the nucleus and are therefore less tightly held. For this reason, iodine atoms can donate electrons or, in other words, exhibit metallic properties, which is not typical for fluorine.

So, the structure of atoms determines two patterns:

a) change in the properties of elements horizontally - in a period, from left to right, metallic properties are weakened and non-metallic properties are enhanced;

b) change in the properties of elements vertically - in a group, with increasing serial number, metallic properties increase and non-metallic properties weaken.

Thus: As the charge of the nucleus of atoms of chemical elements increases, the structure of their electronic shells periodically changes, which is the reason for the periodic change in their properties.

3. Structure periodic Systems of D. I. Mendeleev.

The periodic system of D.I. Mendeleev is divided into seven periods - horizontal sequences of elements arranged in increasing order of atomic number, and eight groups - sequences of elements with the same type of electronic configuration of atoms and similar chemical properties.

The first three periods are called small, the rest - large. The first period includes two elements, the second and third periods - eight each, the fourth and fifth - eighteen each, the sixth - thirty-two, the seventh (incomplete) - twenty-one elements.

Each period (except the first) begins with an alkali metal and ends with a noble gas.

Elements of periods 2 and 3 are called typical.

Small periods consist of one row, large ones - of two rows: even (upper) and odd (lower). Metals are located in even rows of large periods, and the properties of the elements change slightly from left to right. In odd rows of large periods, the properties of the elements change from left to right, as in the elements of periods 2 and 3.

In the periodic system, for each element its symbol and serial number, the name of the element and its relative atomic mass are indicated. The coordinates of the element's position in the system are the period number and the group number.

Elements with serial numbers 58-71, called lanthanides, and elements with numbers 90-103 - actinides - are placed separately at the bottom of the table.

Groups of elements, designated by Roman numerals, are divided into main and secondary subgroups. The main subgroups contain 5 elements (or more). The secondary subgroups include elements of periods starting from the fourth.

The chemical properties of elements are determined by the structure of their atom, or rather the structure of the electron shell of the atoms. Comparison of the structure of electronic shells with the position of elements in the periodic table allows us to establish a number of important patterns:

1. The period number is equal to the total number of energy levels filled with electrons in the atoms of a given element.

2. In small periods and odd series of large periods, as the positive charge of the nuclei increases, the number of electrons in the external energy level increases. This is associated with the weakening of metallic and strengthening of non-metallic properties of elements from left to right.

The group number indicates the number of electrons that can participate in the formation of chemical bonds (valence electrons).

In subgroups, as the positive charge of the nuclei of elemental atoms increases, their metallic properties become stronger and their non-metallic properties weaken.

More from the Chemistry section:

• Abstract: Study of the basic patterns of chemical reactions

DI. Mendeleev on public education

He constantly pursued the idea that the school is a huge force that determines the destinies of peoples and states, and believed that without expanding public education, the very development of Russia is impossible.

In articles and speeches on the state and development of education in Russia, D. I. Mendeleev expressed the following fundamental considerations: public education is the duty of the state to the lower classes. Meanwhile, the country does not even have basic general education for the majority of the child population, especially in villages. A national plan for the development of a network of schools must be developed and a special monetary fund must be available for the implementation of this plan; The fundamental principles of the organization of public education are its universality, compulsoryness and freeness.

Mendeleev was a spontaneous materialist, a revolutionary in science, fought against scholasticism, metaphysics, ignorance and called himself a realist. Dmitry Ivanovich believed that education should be based on “life realism” instead of classicism, and was an advocate of expanding the course of natural sciences at the expense of ancient languages. In his opinion, the basis of general education should be the Russian language, mathematics and natural science. D.I. Mendeleev argued that it is necessary to teach not for personal, but for public purposes. He constantly repeated: “The scientific sowing will come up for the people’s harvest.”

Back in 1871, D.I. Mendeleev wrote that educational institutions can bring the greatest benefit only if there is continuity of education: “By this I mean the opportunity for talented students of lower schools to have an unhindered transition to higher institutions.” He formulated two principles of continuity in training and education: firstly, independence and stability of the content of education at each stage; secondly, the close relationship between primary, secondary and higher education.

D.I. Mendeleev insisted on the introduction of compulsory primary education and state funding of education. Could he have imagined that secondary education would be compulsory these days?

D.I. Mendeleev believed that education should be accessible to all classes.

DI. Mendeleev about secondary school

DI. Mendeleev believed that the main task of secondary education is the development of students’ personality, a conscious attitude towards the environment, hard work, observation, and the ability to discuss important issues. He was a supporter of a strictly thought-out plan of study in secondary school and demanded a certain system of classes and a constant schedule.

The scientist sought to expel from secondary school all manifestations of formalism, rote learning, dead languages ​​(Latin and Greek), and inclusion of vital subjects in the curriculum. Mendeleev believed that teaching should be based on the study of the surrounding reality through experience, observation, analysis and generalization, that is, he advocated intensifying the learning process. D. I. Mendeleev emphasized that reasoning without experimental verification always leads to self-deception and illusions, to a discrepancy between words and deeds, to careerist egoism, which the state does not need at all and leads a lot of people to daydreaming and inactivity, and sometimes to disappointment and despair .

Dmitry Ivanovich’s attitude towards exams in high school is interesting. In the article “Exams” he wrote “... oral, mass exams during training should be abolished, and entrance exams should be looked at only as an inevitable necessity determined by the relationship between demand and supply.”

“...exams, especially oral ones, are always more or less a lottery...it’s time to end this”

Mendeleev was especially outraged by the assessment of teachers' work based on the exam results of their students. He emphasized that testing of teachers is, of course, necessary, but it should, first of all, be carried out when choosing teachers. Teachers should be tested not during exams, but during teaching.

D.I. Mendeleev, highly appreciating the work of the teacher, made the most serious demands on him. He believed that a candidate for a teacher position must have thorough knowledge of the methods of teaching chemistry, and proposed establishing a department of pedagogy at every university. Now every educational institution has a methodological commission on chemistry. “The true work of a teacher,” Mendeleev wrote, “is done exclusively by nerves... dry reasoning alone - even with complete conscientiousness - nothing can be done in teaching, you won’t leave a kind word, the work of nerves is needed...”

Dmitry Ivanovich called teachers lamps and educators, insisted that they follow science, be directly involved in it,

because only that teacher can fruitfully influence his students, replenish their knowledge, who is himself strong in science.

D.I. Mendeleev especially emphasized the educational role of the teacher, that he must know each student, his abilities, inclinations and character in order to comprehensively develop his existing inclinations. In his personal life, a teacher should be an example for students. Trust in the teacher is the basis of all education.

#Dmitriy Mendeleev#story #greatRussian#Mendeleev #chemistry #education

Dmitry Ivanovich Mendeleev was born in February 1834 in the city of Tobolsk, in the family of the director of a local gymnasium. His father, in the year of Dmitry’s birth, became blind in both eyes and, due to this, had to leave the service and go on a meager pension. Raising children and all concerns about a large family fell entirely on the shoulders of the mother, Maria Dmitrievna, an energetic and intelligent woman who, in order to improve the family’s financial situation, took over the management of her brother’s glass factory 25 km from Tobolsk. In 1848, the glass factory burned down, and the Mendeleevs moved to Moscow to live with their mother’s brother. In 1850, after much trouble, Dmitry Ivanovich entered the physics and mathematics department of the St. Petersburg Pedagogical Institute. In 1855, he graduated with a gold medal and was sent as a gymnasium teacher, first to Simferopol, and then to Odessa. However, Mendeleev did not remain in this position for long.

Already in 1856, he went to St. Petersburg and defended his master’s thesis on the topic “On specific volumes,” after which at the beginning of 1857 he was accepted as a private assistant professor in the department of chemistry at St. Petersburg University. 1859 - 1861 he spent on a scientific trip to Germany, at the University of Heidelberg, where he was fortunate to work under the guidance of outstanding scientists Bunsen and Kirchhoff. In 1860, Mendeleev took part in the first international chemical congress in Karlsruhe. Here he was keenly interested in the report of the Italian chemist Cannizzaro. “The decisive moment in the development of my thoughts about the periodic law,” he said many years later, “I consider 1860, the congress of chemists in Karlsruhe... and the ideas expressed at this congress by the Italian chemist Cannizzaro. I consider him to be my real predecessor, since the atomic weights he established provided the necessary fulcrum... The idea of ​​a possible periodicity of the properties of elements with increasing atomic weight, in essence, already appeared to me internally..."

Upon returning to St. Petersburg, Mendeleev began vigorous scientific activity. In 1861, in a few months he wrote the first textbook on organic chemistry in Russia. The book turned out to be so successful that its first edition sold out in a few months and a second edition had to be made the following year. In the spring of 1862, the textbook was awarded the full Demidov Prize. With this money, Mendeleev made a trip abroad in the summer with his young wife Feozva Nikitichnaya Leshcheva. (This marriage was not very successful - in 1881 Mendeleev divorced his first wife, and in April 1882 he married the young artist Anna Ivanovna Popova.) In 1863 he received a professorship at the St. Petersburg Institute of Technology, and in 1866 - at St. Petersburg University, where he lectured on organic, inorganic and technical chemistry. In 1865, Mendeleev defended his doctoral dissertation on the topic “On the combination of alcohol with water.”

In 1866, Mendeleev acquired the Boblovo estate near Klin, with which his entire future life was then connected. Many of his works were written here. In his free time, he was very enthusiastic about farming on the experimental field he had established, where he tested various fertilizers. The old wooden house was dismantled over the course of several years, and a new stone one was built in its place. A model barnyard, dairy, and stable appeared. The threshing machine ordered by Mendeleev was brought to the estate.

In 1867, Mendeleev moved to St. Petersburg University as a professor of chemistry and was supposed to lecture on inorganic chemistry.

Having started preparing lectures, he discovered that neither in Russia nor abroad there was a course in general chemistry worthy of being recommended to students. And then he decided to write it himself. This fundamental work, called “Fundamentals of Chemistry,” was published in separate issues over several years. The first issue, containing an introduction, consideration of general issues of chemistry, description of the properties of hydrogen, oxygen and nitrogen, was completed relatively quickly - it appeared in the summer of 1868. But while working on the second issue, Mendeleev encountered great difficulties associated with the systematization and consistency of presentation of the material . At first he wanted to group all the elements he described by valence, but then he chose a different method and combined them into separate groups, based on the similarity of properties and atomic weight. Reflection on this question brought Mendeleev closely to the main discovery of his life.

The fact that some chemical elements exhibit obvious similarities was not a secret to any chemist of those years. The similarities between lithium, sodium and potassium, between chlorine, bromine and iodine, or between calcium, strontium and barium were striking to anyone. In 1857, the Swedish chemist Lensen combined several “triads” by chemical similarity: ruthenium - rhodium - palladium; osmium - platinum ~ - iridium; manganese - iron - cobalt. Even attempts have been made to compile tables of the elements. The Mendeleev library contained a book by the German chemist Gmelin, who published such a table in 1843. In 1857, the English chemist Odling proposed his own version.

However, none of the proposed systems covered the entire set of known chemical elements. Although the existence of separate groups and separate families could be considered an established fact, the connection between these groups remained completely unclear.

Mendeleev managed to find it by arranging all the elements in order of increasing atomic mass. Establishing a periodic pattern required an enormous amount of thought from him. Having written on separate cards the names of elements indicating their atomic weight and fundamental properties, Mendeleev began to arrange them in various combinations, rearranging and changing places. The matter was greatly complicated by the fact that many elements had not yet been discovered at that time, and the atomic weights of those already known were determined with great inaccuracies. Nevertheless, the desired pattern was soon discovered. Mendeleev himself spoke in this way about his discovery of the periodic law: “Having suspected the existence of a relationship between elements back in my student years, I never tired of thinking about this problem from all sides, collecting materials, comparing and contrasting figures. Finally, the time came when the problem was ripe, when the solution seemed about to take shape in my head. As has always happened in my life, the premonition of an imminent resolution of the question that was tormenting me led me to an excited state. For several weeks I slept in fits and starts, trying to find that magical principle that would immediately put in order the entire pile of material accumulated over 15 years. And then one fine morning, having spent a sleepless night and despairing of finding a solution, I lay down on the sofa without undressing in the office and fell asleep. And in a dream, a table appeared to me quite clearly. I immediately woke up and sketched out the table I saw in a dream on the first piece of paper that came to hand.”

In February 1869, Mendeleev sent out to Russian and foreign chemists, printed on a separate sheet of paper, “An experiment on a system of elements based on their atomic weight and chemical similarity.” On March 6, at a meeting of the Russian Chemical Society, a message was read out about the classification of elements proposed by Mendeleev. This first version of the periodic table was quite different from the periodic table we were accustomed to from school.

The groups were arranged horizontally rather than vertically. The backbone of the table consisted of adjacent groups of alkali metals and halogens. Above the halogens was an oxygen group (sulfur, selenium, tellurium), above it was a nitrogen group (phosphorus, arsenic, antimony, bismuth). Even higher is the carbon group (silicon and tin, between which Mendeleev left an empty cell for an unknown element with an approximate mass of 70 a.u., which was later occupied by germanium with a mass of 72 a.u.) Above the carbon group were placed the boron and beryllium groups. Under the alkali metals there was a group of alkaline earth metals, etc. Several elements, as it turned out later, were placed out of place in this first version. Thus, mercury fell into the group of copper, uranium and gold - into the group of aluminum, thallium - into the group of alkali metals, manganese - into the same group with rhodium and platinum, and cobalt and nickel generally ended up in the same cell. But all these inaccuracies should not at all detract from the importance of the conclusion itself: by comparing the properties of the elements included in the vertical columns, one could clearly see that they change periodically as the atomic weight increases. This was the most important thing in Mendeleev’s discovery, which made it possible to connect together all the previously seemingly disparate groups of elements. Mendeleev quite correctly explained the unexpected disruptions in this periodic series by the fact that not all chemical elements are known to science. In his table, he left four blank cells, but predicted the atomic weight and chemical properties of these elements. He also corrected several inaccurately determined atomic masses of elements, and further research completely confirmed his correctness.

The first, still imperfect draft of the table was reconstructed in the following years. Already in 1869, Mendeleev placed the halogens and alkali metals not in the center of the table, but along its edges (as is done now). All other elements ended up inside the structure and served as a natural transition from one extreme to the other. Along with the main groups, Mendeleev began to distinguish subgroups (thus, the second row was formed by two subgroups: beryllium - magnesium - calcium - strontium - barium and zinc - cadmium - mercury). In the following years, Mendeleev corrected the atomic weights of 11 elements and changed the location of 20. As a result, in 1871, the article “Periodic Law for Chemical Elements” appeared, in which the periodic table took on a completely modern form. The article was translated into German and copies of it were sent to many famous European chemists. But, alas, Mendeleev did not expect from them not only a competent judgment, but even a simple answer. None of them appreciated the importance of the discovery he made. The attitude towards the periodic law changed only in 1875, when Lecoq de Boisbaudran discovered a new element - gallium, the properties of which strikingly coincided with the predictions of Mendeleev (he called this still unknown element equiluminum).

Mendeleev's new triumph was the discovery of scandium in 1879, and germanium in 1886, the properties of which also fully corresponded to Mendeleev's descriptions.

The ideas of the periodic law determined the structure of the “Fundamentals of Chemistry” (the last edition of the course with the periodic table attached to it was published in 1871) and gave this work amazing harmony and fundamentality. In terms of the power of influence on scientific thought, Mendeleev’s “Principles of Chemistry” can easily be compared with such outstanding works of scientific thought as Newton’s “Principles of Natural Philosophy,” Galileo’s “Conversations on the Two Systems of the World,” and Darwin’s “The Origin of Species.” All the vast factual material accumulated by this time on various branches of chemistry was presented here for the first time in the form of a coherent scientific system. Mendeleev himself spoke about the monograph textbook he created: “These “Fundamentals” are my favorite brainchild. They contain my image, my experience as a teacher and my sincere scientific thoughts.” The enormous interest that contemporaries and descendants showed in this book is entirely consistent with the opinion of the author himself. During Mendeleev’s lifetime alone, “Fundamentals of Chemistry” went through eight editions and was translated into major European languages.

In subsequent years, several more fundamental works on various branches of chemistry were published from the pen of Mendeleev. (His complete scientific and literary heritage is enormous and contains 431 published works.) In the mid-80s. he studied solutions for several years, the result of which was the “Study of Aqueous Solutions by Specific Gravity,” published in 1887, which Mendeleev considered one of his best works. In his theory of solutions, he proceeded from the fact that a solvent is an indifferent medium in which it is rarefied a dissolving body, but an actively acting reagent that changes during the dissolution process, and that dissolution is not a mechanical process, but a chemical one. Proponents of the mechanical theory of the formation of solutions, on the contrary, believed that no chemical compounds arise during dissolution, and water molecules, combining in strictly defined proportions with the molecules of the substance, first form a concentrated solution, the mechanical mixture of which with water gives a diluted solution.

Mendeleev imagined this process differently - when combining with molecules of a substance, water molecules form many hydrates, some of which, however, are so fragile that they immediately disintegrate - dissociate. The products of this decomposition again combine with the substance, with the solvent and other hydrates, some of the newly formed compounds dissociate again, and the process continues until a mobile - dynamic - equilibrium is established in the solution.

Mendeleev himself was confident in the correctness of his concept, but, contrary to expectations, his work did not cause much resonance among chemists, since in the same 1887 two more theories of solutions appeared - Van't Hoff's osmotic and Arrhenius's electrolytic - which perfectly explained many of the observed phenomena. For several decades they completely established themselves in chemistry, pushing Mendeleev’s theory into the shadows. But in subsequent years it turned out that both the van't Hoff theory and the Arrhenius theory had a limited scope of application. Thus, Van't Hoff's equations gave excellent results only for organic substances. The Arrhenius theory (according to which decomposition - dissociation - of electrolyte molecules (salts, acids and alkalis) into positively and negatively charged ions occurs in a liquid) turned out to be valid only for weak solutions of electrolytes, but did not explain the main thing - how and due to what forces the splitting occurs the strongest molecules when they enter water. After Mendeleev’s death, Arrhenius himself wrote that the hydrate theory deserves detailed study, because it is it that can provide the key to understanding this, the most difficult issue of electrolytic dissociation. Thus, Mendeleev’s hydration theory, along with the solvate theory of van’t Hoff and the electrolytic theory of Arrhenius, has become an important part of the modern theory of solutions.

Mendeleev's works received wide international recognition. He was elected a member of the American, Irish, Yugoslav, Roman, Belgian, Danish, Czech, Krakow and many other academies of sciences, and an honorary member of many foreign scientific societies. Only the Russian Academy of Sciences voted him out in the elections of 1880 due to some kind of internal intrigue.

After retiring in 1890, Mendeleev took an active part in the publication of the Brockhaus and Efron Encyclopedic Dictionary, then for several years he was a consultant in the gunpowder laboratory at the Naval Ministry. Before this, he had never been specifically involved in explosives, but after conducting the necessary research, in just three years he developed a very effective composition of smokeless gunpowder, which was put into production. In 1893, Mendeleev was appointed custodian (manager) of the Main Chamber of Weights and Measures. He died in February 1907 from pneumonia.