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What elements were predicted by d and Mendeleev. Mendeleev

When compiling the periodic system, D.I.Mendeleev had to overcome many difficulties associated with the fact that some elements were not yet discovered at that time, the properties of others were little studied, the atomic masses of others were determined incorrectly. The scientist deeply believed in the correctness of the law he discovered, was firmly convinced that the periodic law reflects objective reality. On the basis of the periodic table, he corrected the atomic masses of a number of elements, predicted the existence in nature of several not yet discovered elements, and even described the properties of these elements and their compounds. These elements were discovered over the next fifteen years: in 1875, P.E. Lecoq de Boisbaudran discovered element number 31, calling it gallium; in 1879 LF Nilsson discovered element number 21 and named it scandium; in 1886, C.A.Winkler discovered element 32, which was named germanium.

Mendeleev predicted the physical and chemical properties of these three elements based on the properties of the elements surrounding them in the table. For example, he calculated the atomic mass and density of element number 21 as the arithmetic mean of the atomic masses and densities of boron, yttrium, calcium and titanium.

Below, as an example, are given the properties of element with atomic number 32 - germanium, which were predicted by Mendeleev and subsequently experimentally confirmed by Winkler.

Properties of element no. 32, Properties of germanium established

predicted by Mendeleev in 1871: empirically in 1886:

atomic mass - 72; atomic mass - 72.6;

gray refractory metal; gray refractory metal;

density - 5.5 g / cm3; density - 5.35 g / cm3;

should be obtained by reduction is obtained by reduction of oxide

hydrogen oxide; hydrogen;

the oxide formula is EO2; oxide formula - GeO2;

oxide density - 4.7 g / cm3; oxide density - 4.7 g / cm3;

chloride ECl4 - liquid; chloride GeCl4 - liquid;

the density of ECl4 is 1.9 g / cm3; GeCl4 density - 1.887 g / cm3;

the boiling point of ECl4 is 90 ° C. the boiling point of GeCl4 is 90 ° C.

The discovery of the elements foreseen by Mendeleev and the brilliant coincidence of the properties predicted by him with those established empirically led to the universal acceptance of the periodic law.

It should be noted that Mendeleev doubted the possibility of a sharp transition from such active non-metals as halogens to alkali metals. He believed that this transition should be smoother. Soon this scientific prediction came true: inert gases were discovered. There were no free places for these elements in the periodic table, and they were allocated into an independent group. In order to emphasize the great chemical inertness of these elements, the group was named zero.

At present, many variants of the periodic table of elements are known, but the most convenient is the table proposed by D.I.Mendeleev. Some additions were later made to the original version of the table. Some of them were made by the scientist himself.

To date, a number of compounds of heavy noble gases have been obtained, in which the oxidation state is +6 and +8 (XeF6, XeO3, XeO4, etc.). In this regard, inert gases are included in the eighth group of the periodic system, in which they constitute the main subgroup.

DI Mendeleev's periodic table.

The modern periodic table of elements has seven periods, of which I, II, and III are called small periods, and IV, V, VI and VI are called large periods. The I, II and III periods contain one row of elements, IV, V and VI - two rows, the VII period is unfinished. All periods, with the exception of I, which contains only two elements, begin with an alkali metal and end with a noble gas.

CHOREIA (from the Greek. Choreia - dance) (Vittova's dance), rapid involuntary uncoordinated movements, twitching of the limbs, etc.; type of hyperkinesis. Sign of organic brain damage in rheumatism (rheumatic, or small, chorea) or an independent hereditary disease.

DURRELL Gerald Malcolm (1925-1995), English zoologist and writer. Brother of L.J.Durrell. Organizer and participant of expeditions for animal collections to Africa, South. America, Australia. Created a zoo on about. Jersey (1958) for endangered animals. Popular books: "The Land of Rustles" (1961), "The Zoo in My Luggage" (1960), "The Ark on the Island" (1976), etc.

BULBENKOVA Olga Nikolaevna (1835-1918), the creator of a fashion workshop in St. Petersburg in the middle. 19th century, which existed until 1917, known as "Mrs. Olga". The most popular were the court ceremonial dresses made by this workshop, the so-called "trains". See also loop.

They were arranged in accordance with their similar properties in order of increasing atomic weight.

Unlike the works of his predecessors, Mendeleev proceeded from the assumption of the existence of not yet discovered elements on the basis of periodic changes in the physical and chemical properties of known elements. They were left empty cells in the table for not yet opened elements and their properties were predicted. To give the predicted elements "temporary" names, Mendeleev used the prefixes "eka", "dwi" and "three" (from the Sanskrit words "one", "two" and "three"), depending on how many positions down from of an already open element with similar properties, a predicted element was found. So, before its discovery in 1886, germanium was called "ekasilicium", and rhenium, discovered in 1926, was called "dvimarganese".

Already in the first version of the Periodic Table, published by D.I.Mendeleev in 1869, more elements were included than were discovered at that time. It contains four free cells for still unknown elements and indicates their atomic weights (in “shares” close in value to the mass of a hydrogen atom).

Developing the ideas of periodicity in 1869-1871, D.I. Mendeleev introduced the concept of the place of an element in the periodic system as a set of its properties in comparison with the properties of other elements. To predict the properties of simple substances and compounds, he proceeded from the fact that the properties of each element are intermediate between the corresponding properties of two neighboring elements in the group of the periodic table, two neighboring elements in a period and diagonal elements - the so-called "rule of the star". On this basis, in particular, based on the results of studying the sequence of changes in glass-forming oxides, he corrected the atomic masses of 9 elements. He predicted existence in 1870, calculated atomic masses and described the properties of three elements that were not yet discovered at that time - "ekaaluminium", "ekabor" and "ekasilicia". Then he predicted the existence of eight more elements, including "dvitellura" - polonium, "ekaiod" - astatine, "ekamarganese" - technetium, "ekatsia" - france.

Mendeleev's predictions caused skepticism and sharp criticism in the scientific world. Thus, the German physicochemist Wilhelm Ostwald, the future Nobel laureate, argued that it was not the law that was discovered, but the principle of classification of "something indefinite." Robert Bunsen, the discoverer of rubidium and cesium, wrote that Mendeleev fascinates chemists “ into a contrived world of pure abstraction”, And Hermann Kolbe in 1870 called Mendeleev's work speculative. Mendeleev's correctness was convincingly proved when the elements predicted by him were discovered: gallium (Paul Lecoq de Boisabaudran, 1875), scandium (Lars Nilsson, 1879) and germanium (Clemens Winkler, 1886) - respectively, ekaaluminium, ekabor and ecasilicium.

I think there is no need to insist on the enormous importance of confirming the theoretical conclusions of Mr. Mendeleev

The lightest of group zero gases, the first in the Periodic Table, was assigned a theoretical atomic mass of between 5.3 · 10 −11 and 9.6 · 10 −7. Particles of this gas, which he called Newtonium, Mendeleev attributed a kinetic velocity of the order of 2.5 · 10 6 m / s. Almost weightless, the particles of both of these gases, according to Mendeleev, should easily pass through the thickness of matter, practically without entering into chemical reactions. The high mobility and very low atomic mass of trans-hydrogen gases would lead to the fact that they could be very rarefied, while remaining dense in appearance.

Later Mendeleev published a theoretical development about the ether. The book, called The Chemical Concept of Ether, was published in 1904, and it again contained mention of two hypothetical inert gases lighter than hydrogen, coronium and newtonium. By "ethereal gas" Mendeleev understood the interstellar atmosphere, consisting of two trans-hydrogen gases with admixtures of other elements and formed as a result of internal processes going on in the stars.

Initial predictions (1869-1870)

Developing in 1869-1871 the ideas of periodicity, D.I. Mendeleev introduced the concept of the place of an element in the periodic system as a set of its properties in comparison with the properties of other elements. To predict the properties of simple substances and compounds, he proceeded from the fact that the properties of each element are intermediate between the corresponding properties of two neighboring elements in the group of the periodic table, two neighboring elements in a period and diagonal elements - the so-called "rule of the star". On this basis, in particular, relying on the results of studying the sequence of changes in glass-forming oxides, he corrected the atomic masses of 9 elements. He predicted existence in 1870, calculated atomic masses and described the properties of three elements that were not yet discovered at that time - "ekaaluminium", "ekabor" and "ekasilicia". Then he predicted the existence of eight more elements, including "dvitellura" - polonium, "ekaiod" - astatine, "ekamarganese" - technetium, "ekatsia" - france.

Triumph of the Periodic Law

Mendeleev identified the heavier of the two hypothetical trans-hydrogen elements with coronium, which was named after its association with the unexplained spectral line of the solar corona. An incorrect calibration of the instrument gave a wavelength of 531.68 nm, which was later corrected to 530.3 nm. This wavelength was correlated by Grotrian and Edlen in 1939 with the iron line.

Later Mendeleev published a theoretical development about the ether. The book, called The Chemical Concept of Ether, was published in 1904, and it again contained a reference to two hypothetical inert gases lighter than hydrogen, coronium and newtonium. By "ethereal gas" Mendeleev understood the interstellar atmosphere, consisting of two trans-hydrogen gases with admixtures of other elements and formed as a result of internal processes going on in the stars.

Notes

Kaji, Masanori (2002). “D.I.Mendeleev" s concept of chemical elements and The Principles of Chemistry”(PDF). Bulletin for the History of Chemistry. 27 (1): 4-16... Retrieved 2011-02-14.

According to legend, the thought of the system of chemical elements came to Mendeleev in a dream, but it is known that once, when asked how he discovered the periodic system, the scientist replied: “I have been thinking about it for maybe twenty years, but you think: I was sitting and suddenly ... done. "

Unexpected thought
March 1, 1869. It was cloudy and frosty in St. Petersburg that day. Trees creaked in the wind in the university garden, where the windows of Mendeleev's apartment looked out. While still in bed, Dmitry Ivanovich drank a mug of warm milk, then got up, washed himself and went to breakfast. He was in a wonderful mood.

At breakfast Mendeleev had an unexpected idea: to compare the close atomic masses of various chemical elements and their chemical properties.

Without thinking twice, he began to write chemical symbols on a random piece of paper, and then completely, interrupting breakfast, retired to his office. Closing, he took out a pack of business cards from the desk and began to write on their back the symbols of the elements and their main chemical properties. At that time, 63 of them were known. Having laid out these cards, Dmitry Ivanovich began to arrange them, rearrange them from place to place, and play them like a "chemical solitaire".

After a while, the household heard how from the office began to hear: “Oooh! Horned. Wow, how horny! I will overcome those. I'll kill you! " These exclamations meant that Dmitry Ivanovich had a creative inspiration.

On that day, the appearance of the future Periodic Table of Chemical Elements began to take shape. And after it the Periodic Law of Mendeleev.

Throughout the day, Mendeleev worked on the system of elements, taking a short break to play with his daughter Olga, have lunch and dinner.

On the evening of March 1, 1869, he rewrote the table he had compiled, and under the title "Experience of a system of elements based on their atomic weight and chemical similarity" sent it to the printing house, making notes for the typesetters and putting the date "February 17, 1869" (this is the old style). Later, Mendeleev sent the printed leaflets with the table of elements to many domestic and foreign chemists.

SO THE PERIODIC LAW WAS DISCOVERED, THE MODERN FORMULATION OF WHICH IS: "THE PROPERTIES OF SIMPLE SUBSTANCES, AS WELL AS THE FORMS AND PROPERTIES OF COMPOUNDS OF ELEMENTS ARE IN THE PERIODIC DEPENDENCE OF VERIOUS DEPENDENCE.

Mendeleev was then only 35 years old.

N.A. Yaroshenko. Portrait of Dmitry Mendeleev

On March 18, 1869, a short report on the Periodic Law was published on behalf of Mendeleev in the Journal of the Russian Chemical Society. At first, the report did not attract much attention from chemists, and the President of the Russian Chemical Society, Academician Nikolai Zinin (1812-1880) stated that Mendeleev was not doing what a real researcher should do. True, two years later, after reading Dmitry Ivanovich's article "The Natural System of Elements and Its Application to Indicating the Properties of Certain Elements", Zinin changed his mind and wrote to Mendeleev: "Very, very good, a lot of excellent convergence, even fun to read, God bless you in an experienced confirmation of your conclusions. Sincerely devoted to you and deeply respecting you, N. Zinin. "

DI Mendeleev's periodic law is extremely important. He laid the foundation for modern chemistry, made it a unified, integral science. Elements began to be considered interrelated, depending on what place they occupy in the periodic system. The discovery of the Periodic Law hastened the development of chemistry and the discovery of new chemical elements.

On the basis of the periodic law and the periodic system of D. I. Mendeleev, the theory of the structure of the atom developed rapidly. As ND Zelinsky pointed out, the periodic law was "the discovery of the mutual connection of all atoms in the universe."

Criticism from Western colleagues

Not all foreign chemists immediately appreciated the significance of Mendeleev's discovery. It changed a lot in the world of the prevailing ideas. Thus, the German physicochemist Wilhelm Ostwald, the future Nobel laureate, argued that it was not the law that was discovered, but the principle of classifying "something indefinite." The German chemist Robert Bunsen, who discovered in 1861 two new alkaline elements, rubidium Rb and cesium Cs, wrote that Mendeleev carried chemists "into the far-fetched world of pure abstractions."

Leipzig University professor Hermann Kolbe in 1870 called Mendeleev's discovery "speculative." Kolbe was distinguished by his rudeness and rejection of new theoretical views in chemistry. In particular, he was an opponent of the theory of the structure of organic compounds and at one time attacked the article by Jacob van't Hoff "Chemistry in Space". Later, Van't Hoff became the first Nobel laureate for his research. But Kolbe suggested such researchers as Van't Hoff, "to exclude from the ranks of real scientists and enroll them in the camp of spiritualists"!

Every year the Periodic Law has won an increasing number of supporters, and its discoverer - more and more recognition. High-ranking visitors began to appear in Mendeleev's laboratory, including even the Grand Duke Konstantin Nikolaevich, the head of the naval department.

Mendeleev's prediction and triumph

Chemistry, thanks to Mendeleev, ceased to be a descriptive science. With the discovery of the periodic law, scientific foresight became possible in it. Now it is possible to predict and describe new elements and their connections that have not yet been discovered. A brilliant example of this is D. I. Mendeleev's prediction of the existence of elements not yet discovered in his time, of which for three - Ga, Sc, Ge - he gave an accurate description of their properties.

Following unexpected criticism from Western colleagues, the time for triumph finally came.

In 1875, the French chemist Paul-Emile Lecoq de Boisbaudran discovered wurtzite, predicted by Mendeleev "ekaaluminium" and named it in honor of his homeland gallium Ga (the Latin name for France is "Gaul"). The humble French wrote:

“I THINK THERE IS NO NEED TO INSIST ON THE HUGE VALUE OF CONFIRMATION OF THE THEORETICAL CONCLUSIONS OF MRS. MENDELEEV.”

Note that the name of the element also hints at the name of Boisbaudran himself. The Latin word "gallus" means rooster, and in French the rooster means "le coke". This word is also in the name of the discoverer. What Lecoq de Boisbaudran had in mind when he gave the name to the element - himself or his country - this, apparently, will never be clear.

It is known for certain that Dmitry Ivanovich Mendeleev accurately predicted the properties of eka-aluminum: its atomic mass, metal density, the formula of the oxide El2O3, chloride ElCl3, sulfate El2 (SO4) 3. After the discovery of gallium, these formulas began to be written as Ga2O3, GaCl3 and Ga2 (SO4) 3. Mendeleev predicted that it would be a very low-melting metal, and indeed, the melting point of gallium turned out to be 29.8 ° C. In terms of low melting point, gallium is second only to mercury Hg and cesium Cs.

In 1879, Swedish chemist Lars Nilsson discovered scandium, predicted by Mendeleev as ekabor Eb. Nilsson wrote:

“THERE IS NO DOUBT THAT AN ECABOR WAS OPENED IN SCANDIA ...

Scandium was named after Nilson's homeland of Scandinavia, and he discovered it in the complex mineral gadolinite.

In 1886, a professor at the Mining Academy in Freiburg, German chemist Clemens Winkler, while analyzing a rare mineral, argyrodite, discovered another element predicted by Mendeleev. Winkler named the element Ge, which he discovered, after his homeland, but for some reason this caused sharp objections from some chemists. They began to accuse Winkler of nationalism, of appropriating the discovery made by Mendeleev, who had already given the element the name "ekasiliciy" and the symbol Es. Discouraged, Winkler turned to Dmitry Ivanovich himself for advice. He explained that it was the discoverer of the new element that should give it a name.

IN 1905 MENDELEEV WRITTEN: "APPARELY, TO A PERIODIC LAW THE FUTURE IS NOT THREATENED WITH DESTRUCTION, BUT ONLY SUPERSTRUCTIONS AND DEVELOPMENT PROMISES, ALTHOUGH AS THE RUSSIAN ME WANTED NOT TO BE LOST."

Why did not receive the Nobel Prize

As you know, Mendeleev, like Tolstoy, Chekhov, Gorky, unexpectedly for everyone, were not awarded the international Nobel Prize. On this occasion, even at a meeting of the Bureau of the Division of Physical and Mathematical Sciences of the Academy of Sciences of the USSR on November 1, 1955, a refusal to nominate Soviet scientists for the Nobel Prize in 1956 was announced (in the minutes this is item 19). The motive is this:

“This prize cannot be considered international in view of the fact that the Nobel Committee at one time did not consider it necessary to award this prize to outstanding figures in science and culture of our country (D. I. Mendeleev, L. N. Tolstoy, A. P. Chekhov, M. Gorky ) "

The motive is very compelling. But the authors of this statement did not take into account an interesting fact, which is usually not spoken about out loud. To be more precise, they could not have known about it, because the secrecy label was removed much later and what happened in the first decade of the XX century in the Nobel Committee became known only in the 1960s.

It was found that the great chemist Dmitry Ivanovich Mendeleev, who died 73 years old on February 2, 1907, was nominated (exhibited) for the Nobel Prize (which, we recall, has been awarded since 1901) three times - in 1905, 1906 and 1907. However, in a secret ballot, which was held by members of the Imperial Academy of Sciences, his candidacy was constantly failed, and one of the most compelling reasons - the creator of the Periodic Table of the Elements was nominated exclusively by foreigners, not compatriots. All of this is reflected in the archives of the Royal Academy of Sciences in Stockholm.

It so happened that only foreign connoisseurs of his work, the Swedes, first of all, defended the great discovery and priority of the Russian thinker. As for the domestic scientific community, according to S.Yu. Witte, it stirred up

"ONLY WHEN HE DIED" AND WHEN "STARTED TO SCREAM THAT WE HAVE LOST THE GREAT RUSSIAN SCIENTIST. IT'S GOOD THAT THE RUSSIANS GAVE THIS HONOR TO HIM AFTER HIS DEATH, ALTHOUGH IT WOULD BE PLEASANT FOR MENDELEEV IF HIS DIGNITIES WERE ESTIMATED DURING HIS LIFE "

One of the main reasons why there was not a single compatriot among its nominators (scientists entitled to nominate candidates) were the envy of ill-wishers and the rather difficult character of the scientist. Finance Minister Witte also mentioned this in his memoirs.

But there was something else besides the complexity of character.

Mendeleev was a patriot of his country and free in the search for truth and therefore inconvenient for power. Few people know that a world-famous scientist, author of fundamental research in chemistry, physics, metrology, aeronautics, meteorology, agriculture, economics and chemical technology was expelled back in 1880 (according to another version - he left) from the university because of conflict with the Minister of Education, who, during the student unrest, refuses to accept the students' petition from Mendeleev.

I. N. Kramskoy. D.I.Mendeleev. 1878.

However, there was also a completely objective component that limited the possibility of his nomination for the Nobel Prize. The fact is that one of the main requirements during the first four decades of the functioning of the Nobel institutions was the inevitable novelty of the discovery. This requirement, repeated in the charter, was provided for by Alfred Nobel himself in his will. And that is why Mendeleev's scientific breakthrough in the creation of the Periodic Table of Elements, dated 1869, when he published his "Experience of a system of elements based on their atomic weight and chemical affinity", did not fit into the Procrustean bed of the strictly followed charter.

But there is another version why Mendeleev did not receive the award.

Fighting the predatory consumption of hydrocarbons, Mendeleev also comes into conflict with Ludwig Nobel, the elder brother of the famous Alfred, and his associates. Taking advantage of the oil crisis and striving for a monopoly on the production and distillation of Baku oil, the Nobels speculated on rumors of its depletion. Mendeleev proved the unfoundedness of such rumors, to the displeasure of Nobel. By the way, it was Mendeleev who, back in the 1860s, proposed the construction of oil pipelines and the delivery of crude oil to Central Russia with their help. However, the Nobels, well aware of the benefits of this for the Russian state, reacted extremely negatively to his proposal, since they saw this as damage to their own monopoly. However, exactly 20 years later, the Nobels successfully implemented Mendeleev's proposal as their own.

DI Mendeleev's scientific authority was enormous. The list of titles and titles includes more than one hundred titles. Almost all Russian and most of the most respected foreign academies, universities and scientific societies, he was elected as their honorary member. Nevertheless, he signed his works, private and official appeals without indicating any involvement in them: “D. Mendeleev "or" Professor Mendeleev ", rarely mentioning any honorary titles awarded to him.

In a private letter to S. Yu. Witte, which remained unsent, D. I. Mendeleev, stating and evaluating his many years of activity, calls "three services to the Motherland":

“The fruits of my labors are, first of all, scientific fame, which is my pride - not only my personal, but also the general Russian ... When meeting them, I always heard that the seed was good in them, and not a simple service ... My third service to the Motherland is the least visible, although it worried me from a young age until now. This is a service to the best of our ability and opportunity for the benefit of the growth of Russian industry ... "

On January 20, at 5 hours 20 minutes, the heart of the great Russian man and great scientist stopped ...

The thaw struck on the day of the funeral. The snow turned into wet mush. Lanterns, entwined with a black veil, flickered dimly through the misty haze. ”The procession of many thousands stretched for a long time through the streets of St. Petersburg to the Volkov cemetery. And when everyone gathered at the grave, it was already the early twilight of a short northern day.

“Great teacher! Glory to the Russian land! - said at the grave D. Konovalov, a student of Mendeleev. - Your covenants will not die. Your spirit will always live between us and will always instill faith in a bright future. May your native land be easy for you! "

It began to darken quickly. The crowd began to slowly disperse, and soon at the burial site there was a small elevation of frozen ground, buried in flowers and wreaths. Nearby, leaning against the wall of the crypt, proudly towering over the flowers, was a cardboard table with the periodic table, torn by students of the Institute of Technology from the classroom wall. And this unusual neighborhood of gray dull cardboard with flowers and upturned earth gave exciting significance and solemnity to what had happened.

Exactly one year later, relatives, friends and colleagues gathered for a memorial service at Mendeleev's grave. In mournful silence they crowded around a cement crypt slightly elevated above the ground, surrounded by granite pedestals with iron chains. A granite block topped with a massive cross towered over the grave. Because of the severe frosts, the masons managed to knock out only three words on the granite: Dmitry Ivanovich MENDELEEV.

The dowager Anna Ivanovna was especially embarrassed by this imperfection. And suddenly, right behind her, someone said: "It's so good that there is nothing on the monument except the name - Dmitry Ivanovich Mendeleev - it is on this grave that you don't need to write anything else."

And neither a bust of Dmitry Ivanovich, nor a bas-relief, nor quotes, nor a full title appeared on the monument, which he never wished to sign during his lifetime ...

Dmitri Ivanovich Mendeleev
(January 27, 1834, Tobolsk - January 20, 1907, St. Petersburg)

Russian encyclopedic scientist: chemist, physicochemist, physicist, metrologist, economist, technologist, geologist, meteorologist, oilman, teacher, aeronaut, instrument-maker. Professor of St. Petersburg University; Corresponding member of the category "physical" of the Imperial St. Petersburg Academy of Sciences. Among the most famous discoveries is the periodic law of chemical elements, one of the fundamental laws of the universe, inherent in all natural science. The author of the classic work "Fundamentals of Chemistry".

Mendeleev was then only 35 years old.

Mendeleev sent the printed leaflets with the table of elements to many domestic and foreign chemists, and only after that he left Petersburg to inspect the cheese dairy.
Before leaving, he still managed to hand over to NA Menshutkin, an organic chemist and future historian of chemistry, the manuscript of the article "Correlation of properties with the atomic weight of elements" - for publication in the Journal of the Russian Chemical Society and for communication at the upcoming meeting of the society.

On March 18, 1869, Menshutkin, who at that time was the clerk of the society, made a short report on the Periodic Law on behalf of Mendeleev. At first, the report did not attract much attention from chemists, and the President of the Russian Chemical Society, Academician Nikolai Nikolayevich Zinin (1812-1880) stated that Mendeleev was not doing what a real researcher should do. True, two years later, after reading Dmitry Ivanovich's article "The Natural System of Elements and Its Application to Indicating the Properties of Certain Elements", Zinin changed his mind and wrote to Mendeleev: "Very, very good, a lot of excellent convergence, even fun to read, God bless you in experimental confirmation of your conclusions. Sincerely devoted to you and deeply respecting you N. Zinin. "

So what is periodicity?

This is the repeatability of the chemical properties of simple substances and their compounds when the ordinal number of an element changes. Z and the appearance of a number of properties of maxima and minima, depending on the value of the ordinal (atomic) number of the element.

For example, what makes it possible to combine all alkaline elements into one group?

First of all, repeatability at some intervals of values Z electronic configuration. The atoms of all alkaline elements have only one electron in the outer atomic orbital, and therefore in their compounds they exhibit the same oxidation state, equal to + I. The formulas of their compounds are of the same type: for chlorides MCl, for carbonates - M 2 CO 3, for acetates - CH 3 COOM and so on (here the letter M denotes an alkaline element).

After the discovery of the Periodic Law, Mendeleev still had a lot to do. The reason for the periodic change in the properties of the elements remained unknown, and the very structure of the Periodic Table itself, where the properties were repeated after seven elements in the eighth, could not be explained. However, the first veil of mystery was removed from these numbers: in the second and third periods of the system, there were just seven elements each.

Not all elements were arranged by Mendeleev in the order of increasing atomic masses; in some cases he was more guided by the similarity of chemical properties. So, at cobalt Co atomic mass is greater than that of nickel Ni, y tellurium Te it is also larger than that of iodine I, but Mendeleev placed them in the order Co - Ni, Te - I, and not vice versa. Otherwise tellurium would fall into the group halogens, and iodine became a relative selena Se.

The most important thing in the discovery of the Periodic Law is prediction existence of not yet discovered chemical elements. Under aluminum Al Mendeleev left room for his analogue " ekaaluminium", under boron B - for " ekabora"and under silicon Si - for " ekasilicon"That is how Mendeleev called the not yet discovered chemical elements. He even gave them the symbols El, Eb and Es.

Regarding the element "ekasilitsiya" Mendeleev wrote: "It seems to me that the most interesting of the undoubtedly missing metals will be the one that belongs to the IV group of carbon analogs, namely, the III row. This will be the metal immediately following silicon, and therefore we will call its ekasilicon ". Indeed, this not yet open element was supposed to become a kind of "lock" connecting two typical non-metals - carbon C and silicon Si - with two typical metals - tin Sn and lead Pb.

Not all foreign chemists immediately appreciated the significance of Mendeleev's discovery. It changed a lot in the world of the prevailing ideas. Thus, the German physicochemist Wilhelm Ostwald, the future Nobel laureate, argued that it was not the law that was discovered, but the principle of classifying "something indefinite." German chemist Robert Bunsen, who discovered two new alkaline elements in 1861, rubidium Rb and cesium Cs, wrote that Mendeleev carried chemists "into the contrived world of pure abstractions."

Professor of Leipzig University Hermann Kolbe in 1870 called Mendeleev's discovery "speculative". Kolbe was distinguished by his rudeness and rejection of new theoretical views in chemistry. In particular, he was an opponent of the theory of the structure of organic compounds and at one time attacked the article by Jacob van't Hoff "Chemistry in Space". Later, Van't Hoff became the first Nobel laureate for his research. But Kolbe suggested such researchers as Van't Hoff "exclude from the ranks of real scientists and enroll them in the camp of spiritualists"!

Triumph

Finally, it was time for triumph. In 1875, the French chemist Paul-Émile Lecoq de Boisbaudran discovered in the mineral wurtzite - zinc sulfide ZnS - predicted by Mendeleev " ekaaluminum"and named him after his homeland gallium Ga (the Latin name for France is "Gaul"). He wrote: "I think there is no need to insist on the great importance of confirming the theoretical conclusions of Mr. Mendeleev."

Note that in the name of the element there is a hint of the name of Boisbaudran himself. The Latin word "gallus" means rooster, and in French the rooster means "le coke". This word is also in the name of the discoverer. What Lecoq de Boisbaudran had in mind when he gave the name to the element - himself or his country - this, apparently, will never be clear.

Mendeleev accurately predicted the properties of eka-aluminum: its atomic mass, metal density, the formula of the oxide El 2 O 3, chloride ElCl 3, sulfate El 2 (SO 4) 3. After the discovery of gallium, these formulas began to be written as Ga 2 O 3, GaCl 3 and Ga 2 (SO 4) 3. Mendeleev predicted that it would be a very low-melting metal, and indeed, the melting point of gallium turned out to be equal to 29.8 ° C. In terms of low melting point, gallium is second only to mercury Hg and cesium Cs.

In 1879, the Swedish chemist Lars Nilsson discovered scandium, which Mendeleev predicted as ekabor Eb. Nilsson wrote: "There is no doubt that in scandia open ekabor... This is how the considerations of the Russian chemist are vividly confirmed, which not only made it possible to predict the existence of scandium and gallium, but also to foresee their most important properties in advance. " composition Be 2 (Y, Sc) 2 FeO 2 (SiO 4) 2.

In 1886, a professor at the Mining Academy in Freiburg, German chemist Clemens Winkler, while analyzing a rare mineral argyrodite of the composition Ag 8 GeS 6, discovered another element predicted by Mendeleev. Winkler named the element he discovered germany Ge in honor of his homeland, but for some reason this caused strong objections from some chemists. They began to accuse Winkler of nationalism, of appropriating the discovery made by Mendeleev, who had already given the name to the element " ekasilicon"and the symbol E. The discouraged Winkler turned to Dmitry Ivanovich himself for advice. He explained that it was the discoverer of the new element who should give it a name.

Mendeleev could not predict the existence of a group of noble gases, and at first there was no place for them in the Periodic Table.
Opening argon English scientists W. Ramsay and J. Rayleigh in 1894 immediately caused heated discussions and doubts about the Periodic Law and the Periodic Table of Elements. Mendeleev at first considered argon to be an allotropic modification of nitrogen and only in 1900, under the pressure of immutable facts, agreed with the presence in the Periodic Table of the "zero" group of chemical elements, which was occupied by other noble gases, which were discovered after argon. This group is now known under the number VIIIA.

In 1905, Mendeleev wrote: "Apparently, the future does not threaten the periodic law with destruction, but only promises superstructures and development, although they wanted to wipe me out as a Russian, especially the Germans."

The discovery of the Periodic Law hastened the development of chemistry and the discovery of new chemical elements.

Initial predictions (1869-1870)

Triumph of the Periodic Law

Notes

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