In fact, the German physicist Johann Wolfgang Dobereiner noticed the grouping of elements as early as 1817. In those days, chemists had not yet fully understood the nature of atoms, as described by John Dalton in 1808. In his "New System of Chemical Philosophy", Dalton explained chemical reactions by assuming that each elemental substance is composed of a particular type of atom.

Dalton suggested that chemical reactions produced new substances when atoms were separated or combined. He believed that any element consists exclusively of one type of atom, which differs from others in weight. Oxygen atoms weighed eight times more than hydrogen atoms. Dalton believed that carbon atoms are six times heavier than hydrogen. When elements combine to create new substances, the amount of reactants can be calculated from these atomic weights.

Dalton was wrong about some masses - oxygen is actually 16 times heavier than hydrogen, and carbon is 12 times heavier than hydrogen. But his theory made the idea of ​​atoms useful, inspiring a revolution in chemistry. Accurate measurement of atomic mass became a major problem for chemists for decades to come.

Reflecting on these scales, Dobereiner noted that certain sets of three elements (he called them triads) show an interesting relationship. Bromine, for example, had an atomic mass somewhere between that of chlorine and iodine, and all three of these elements exhibited similar chemical behavior. Lithium, sodium and potassium were also a triad.

Other chemists noticed links between atomic masses and , but only in the 1860s. atomic masses have become well enough understood and measured to develop a deeper understanding. The English chemist John Newlands noticed that the arrangement of known elements in order of increasing atomic mass led to the repetition of the chemical properties of every eighth element. This model he called the "law of octaves" in an 1865 paper. But Newlands' model did not hold up very well after the first two octaves, leading critics to suggest that he alphabetize the elements. And as Mendeleev soon realized, the relationship between the properties of elements and atomic masses was a little more complex.

Organization of chemical elements

Mendeleev was born in Tobolsk, Siberia, in 1834, the seventeenth child of his parents. He lived a colorful life, pursuing different interests and traveling along the road to outstanding people. At the time of receipt higher education at the Pedagogical Institute in St. Petersburg, he almost died from a serious illness. After graduation, he taught in secondary schools (this was necessary in order to receive a salary at the institute), simultaneously studying mathematics and natural Sciences for a master's degree.

He then worked as a teacher and lecturer (and wrote scientific work), until he received a scholarship for an extended research tour in the best chemical laboratories in Europe.

Back in St. Petersburg, he found himself out of a job, so he wrote an excellent guide to programming in the hope of winning a big cash prize. In 1862 it won him the Demidov Prize. He also worked as an editor, translator and consultant in various chemical fields. In 1865 he returned to research, received a doctorate and became a professor at St. Petersburg University.

Shortly thereafter, Mendeleev began teaching inorganic chemistry. Preparing to master this new (for him) field, he was dissatisfied with the available textbooks. So I decided to write my own. The organization of the text required the organization of the elements, so the question of their best arrangement was constantly on his mind.

By early 1869, Mendeleev had made enough progress to realize that certain groups of similar elements exhibited a regular increase in atomic masses; other elements with roughly the same atomic masses had similar properties. It turned out that ordering the elements by their atomic weight was the key to their classification.

Periodic table of D. Meneleev.

In Mendeleev's own words, he structured his thinking by writing down each of the 63 elements then known on a separate card. Then, through a kind of chemical solitaire game, he found the pattern he was looking for. Arranging cards in vertical columns with atomic masses from low to high, he placed elements with similar properties in each horizontal row. The periodic table of Mendeleev was born. He drafted a draft on March 1, sent it to print, and included it in his soon-to-be-published textbook. He also quickly prepared a paper for presentation to the Russian Chemical Society.

"Elements ordered by the size of their atomic masses show clear periodic properties," Mendeleev wrote in his work. "All the comparisons I have made have led me to the conclusion that the size of the atomic mass determines the nature of the elements."

Meanwhile, the German chemist Lothar Meyer was also working on organizing the elements. He prepared a table similar to Mendeleev's, perhaps even earlier than Mendeleev's. But Mendeleev published his first.

However, much more important than defeating Meyer was how Mendeleev used his table to make about undiscovered elements. In preparing his table, Mendeleev noticed that some cards were missing. It had to leave empty spaces so known elements could align properly. Even during his lifetime, three empty spaces were filled with previously unknown elements: gallium, scandium and germanium.

Mendeleev not only predicted the existence of these elements, but also correctly described their properties in detail. Gallium, for example, discovered in 1875, had an atomic mass of 69.9 and a density six times that of water. Mendeleev predicted this element (he called it ekaaluminum) only from this density and atomic mass 68. His predictions for ekasilicon closely matched germanium (discovered in 1886) in atomic mass (72 predicted, 72.3 actual) and density. He also correctly predicted the density of germanium compounds with oxygen and chlorine.

The periodic table has become prophetic. It seemed that at the end of this game this solitaire of the elements would reveal. At the same time, Mendeleev himself was a master in using his own table.

Mendeleev's successful predictions earned him legendary status as a master of chemical wizardry. But historians today debate whether the discovery of the predicted elements solidified the adoption of his periodic law. The passage of a law may have had more to do with its ability to explain established chemical bonds. In any case, Mendeleev's predictive accuracy certainly drew attention to the merits of his table.

By the 1890s, chemists widely recognized his law as a milestone in chemical knowledge. In 1900, the future Nobel laureate in chemistry, William Ramsay called it "the greatest generalization ever made in chemistry". And Mendeleev did it without understanding how.

math map

In many cases in the history of science, great predictions based on new equations have turned out to be correct. Somehow, mathematics reveals some of nature's secrets before experimenters discover them. One example is antimatter, another is the expansion of the universe. In Mendeleev's case, predictions of new elements arose without any creative mathematics. But in fact, Mendeleev discovered a deep mathematical map of nature, since his table reflected the meaning of , the mathematical rules that govern atomic architecture.

In his book, Mendeleev noted that "the internal differences in the matter which make up the atoms" may be responsible for the periodically repeating properties of the elements. But he did not follow this line of thinking. In fact, for many years he pondered how important atomic theory was to his table.

But others were able to read the inner message of the table. In 1888, German chemist Johannes Wieslicen announced that the periodicity of the properties of elements ordered by mass indicates that atoms are composed of regular groups of smaller particles. Thus, in a sense, the periodic table did foresee (and provided evidence for) the complex internal structure of atoms, while no one had the faintest idea of ​​what the atom actually looked like or if it had any internal structure at all.

By the time of Mendeleev's death in 1907, scientists knew that atoms are divided into parts: , plus some positively charged component that makes the atoms electrically neutral. The key to how these parts line up came in 1911, when physicist Ernest Rutherford, working at the University of Manchester in England, discovered the atomic nucleus. Shortly thereafter, Henry Moseley, working with Rutherford, demonstrated that the amount of positive charge in a nucleus (the number of protons it contains, or its "atomic number") determines correct order elements in the periodic table.

Henry Moseley.

Atomic mass was closely related to Moseley's atomic number—close enough that the ordering of the elements by mass differed only in a few places from the ordering by number. Mendeleev insisted that these masses were wrong and needed to be measured again, and in some cases he was right. There are a few discrepancies left, but Moseley's atomic number fit nicely into the table.

Around the same time, the Danish physicist Niels Bohr realized that quantum theory determines the arrangement of the electrons surrounding the nucleus, and that the outermost electrons determine Chemical properties element.

Similar arrangements of outer electrons will be repeated periodically, explaining the patterns that the periodic table originally revealed. Bohr created his own version of the table in 1922, based on experimental measurements electron energies (along with some clues from the periodic law).

Bohr's table added elements discovered since 1869, but it was the same periodic order discovered by Mendeleev. Without having the slightest idea of ​​\u200b\u200b, Mendeleev created a table reflecting the atomic architecture that quantum physics dictated.

Bohr's new table was neither the first nor the last version of Mendeleev's original design. Hundreds of versions of the periodic table have since been developed and published. The modern form - in a horizontal design as opposed to Mendeleev's original vertical version - did not become widely popular until after World War II, largely due to the work of the American chemist Glenn Seaborg.

Seaborg and his colleagues have created several new elements synthetically, with atomic numbers after uranium, the last natural element on the table. Seaborg saw that these elements, transuranic (plus the three elements that preceded uranium), required a new line in the table that Mendeleev had not foreseen. Seaborg's table added a row for those elements under the similar row of rare earth elements that also did not have a place in the table.

Seaborg's contribution to chemistry earned him the honor of naming his own element, seaborgium, number 106. It is one of several elements named after famous scientists. And in this list, of course, there is element 101, discovered by Seaborg and his colleagues in 1955 and named mendelevium - in honor of the chemist who, above all others, deserved a place in the periodic table.

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2.2. The history of the creation of the Periodic system.

In the winter of 1867-68, Mendeleev began to write the textbook "Fundamentals of Chemistry" and immediately encountered difficulties in systematizing the factual material. By mid-February 1869, while pondering the structure of the textbook, he gradually came to the conclusion that the properties simple substances(and this is a form of existence chemical elements in a free state) and the atomic masses of the elements are connected by a certain regularity.

Mendeleev did not know much about the attempts of his predecessors to arrange the chemical elements in order of increasing atomic masses and about the incidents that arose in this case. For example, he had almost no information about the work of Chancourtois, Newlands, and Meyer.

The decisive stage of his thoughts came on March 1, 1869 (February 14, old style). A day earlier, Mendeleev wrote a request for a ten-day vacation to inspect artel cheese factories in the Tver province: he received a letter with recommendations on studying cheese production from A. I. Khodnev, one of the leaders of the Free Economic Society.

Petersburg that day was cloudy and frosty. The 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. His mood was wonderful.

At breakfast, Mendeleev had an unexpected idea: to compare close atomic masses of various chemical elements and their chemical properties. Without thinking twice, on the reverse side of Khodnev's letter, he wrote down the symbols for chlorine Cl and potassium K with fairly similar atomic masses, equal to 35.5 and 39, respectively (the difference is only 3.5 units). In the same letter, Mendeleev sketched symbols of other elements, looking for similar "paradoxical" pairs among them: fluorine F and sodium Na, bromine Br and rubidium Rb, iodine I and cesium Cs, for which the mass difference increases from 4.0 to 5.0 and then to 6.0. At that time Mendeleev could not have known that the "indefinite zone" between explicit non-metals and metals contained elements - noble gases, the discovery of which would later significantly modify the Periodic Table.

After breakfast, Mendeleev closed himself in his office. He took out a pack of business cards from the desk and began to write the symbols of the elements and their main chemical properties on their reverse side. After a while, the household heard how it began to be heard from the office: "Uuu! Horned one. Wow, what a horned one! I will overcome them. I will kill them!" These exclamations meant that Dmitry Ivanovich had a creative inspiration. Mendeleev shifted the cards from one horizontal row to another, guided by the values ​​of the atomic mass and the properties of simple substances formed by atoms of the same element. Once again, thorough knowledge came to his aid inorganic chemistry. Gradually, the appearance of the future Periodic Table of chemical elements began to take shape. So, at first he put a card with the element beryllium Be (atomic mass 14) next to the card of the aluminum element Al (atomic mass 27.4), according to the then tradition, taking beryllium for an analogue of aluminum. However, then, comparing the chemical properties, he placed beryllium over magnesium Mg. Having doubted the then generally accepted value of the atomic mass of beryllium, he changed it to 9.4, and changed the formula of beryllium oxide from Be 2 O 3 to BeO (like magnesium oxide MgO). By the way, the "corrected" value of the atomic mass of beryllium was confirmed only ten years later. He acted just as boldly on other occasions.

Gradually, Dmitry Ivanovich came to the final conclusion that the elements, arranged in ascending order of their atomic masses, show a clear periodicity in physical and chemical properties. Throughout the day, Mendeleev worked on the system of elements, taking short breaks to play with his daughter Olga, have lunch and dinner.

On the evening of March 1, 1869, he whitewashed the table he had compiled and, under the title "Experiment of a system of elements based on their atomic weight and chemical similarity," sent it to the printer, making notes for typesetters and putting the date "February 17, 1869" (this is according to the old style).

This is how the Periodic Law was discovered, the modern formulation of which is as follows: The properties of simple substances, as well as the forms and properties of compounds of elements, are in a periodic dependence on the charge of the nuclei of their atoms.

Mendeleev sent printed sheets with a table of elements to many domestic and foreign chemists, and only after that he left St. Petersburg to inspect cheese factories.

Before his departure, he still managed to hand over to N. A. Menshutkin, an organic chemist and future historian of chemistry, the manuscript of the article "Relationship 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 small report on the Periodic Law on behalf of Mendeleev. The report at first did not attract much attention of 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 an article by Dmitry Ivanovich " natural system elements and its application to indicate the properties of certain elements, "Zinin changed his mind and wrote to Mendeleev: "Very, very good, very excellent approximations, even fun to read, God bless you in experimental confirmation of your conclusions. N. Zinin, sincerely devoted to you and deeply respecting you." Mendeleev did not place all the elements in ascending order of atomic masses; in some cases, he was more guided by the similarity of chemical properties. So, cobalt Co has an atomic mass greater than nickel Ni, 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 halogen group, and iodine would become a relative of selenium Se.

To his wife and children. Or maybe he knew that he was dying, but did not want to disturb and excite the family in advance, whom he loved passionately and tenderly. At 5:20 a.m. January 20, 1907 Dmitry Ivanovich Mendeleev died. He was buried at the Volkovsky cemetery in St. Petersburg, not far from the graves of his mother and son Vladimir. In 1911, the Museum of D.I. Mendeleev, where ...

Moscow metro station, research ship for oceanographic research, 101st chemical element and mineral - mendeleevite. Russian-speaking scientists-jokers sometimes ask: "Isn't Dmitry Ivanovich Mendeleev a Jew, a painfully strange surname, didn't it come from the surname "Mendel"?" The answer to this question is extremely simple: "All four sons of Pavel Maksimovich Sokolov, ...

Lyceum exam, where old Derzhavin blessed the young Pushkin. The role of the meter happened to be played by Academician Yu.F. Fritsshe, a well-known specialist in organic chemistry. PhD thesis D.I. Mendeleev graduated from the Chief Pedagogical Institute in 1855. The Ph.D. thesis "Isomorphism in connection with other relations of crystalline form to composition" became his first major scientific ...

Mostly on the issue of capillarity and surface tension of liquids, and he spent his leisure time in the circle of young Russian scientists: S.P. Botkin, I.M. Sechenov, I.A. Vyshnegradsky, A.P. Borodina and others. In 1861, Mendeleev returned to St. Petersburg, where he resumed lecturing on organic chemistry at the university and published a textbook remarkable for that time: " Organic chemistry", in...

How it all began?

Many well-known eminent chemists at the turn of the XIX-XX centuries have long noticed that the physical and chemical properties of many chemical elements are very similar to each other. For example, Potassium, Lithium and Sodium are all active metals, which, when interacting with water, form active hydroxides of these metals; Chlorine, Fluorine, Bromine in their compounds with hydrogen showed the same valence equal to I and all these compounds are strong acids. From this similarity, the conclusion has long been suggested that all known chemical elements can be combined into groups, and so that the elements of each group have a certain set of physicochemical characteristics. However, such groups were often incorrectly compiled from different elements by various scientists, and for a long time one of the main characteristics of the elements was ignored by many - this is their atomic mass. It was ignored because it was and is different for different elements, which means it could not be used as a parameter for grouping. The only exception was the French chemist Alexander Emile Chancourtua, who tried to arrange all the elements in a three-dimensional model along a helix, but his work was not recognized by the scientific community, and the model turned out to be cumbersome and inconvenient.

Unlike many scientists, D.I. Mendeleev took the atomic mass (in those days, even " Atomic weight") as a key parameter in the classification of elements. In his version, Dmitry Ivanovich arranged the elements in ascending order of their atomic weights, and here a pattern emerged that at certain intervals of elements their properties periodically repeat. True, exceptions had to be made: some elements were swapped and not corresponded to the increase in atomic masses (for example, tellurium and iodine), but they corresponded to the properties of the elements.Further development of the atomic and molecular theory justified such shifts and showed the validity of this arrangement.You can read more about this in the article "What is the discovery of Mendeleev"

As we can see, the arrangement of elements in this version is not at all what we see in the modern form. Firstly, groups and periods are reversed: groups horizontally, periods vertically, and secondly, there are a bit too many groups in it - nineteen, instead of eighteen accepted today.

However, just a year later, in 1870, Mendeleev formed a new version of the table, which is already more recognizable to us: similar elements are lined up vertically, forming groups, and 6 periods are arranged horizontally. It is especially noteworthy that in both the first and second versions the tables are visible significant achievements that his predecessors did not have: places were carefully left in the table for elements that, according to Mendeleev, had yet to be discovered. The corresponding vacancies are indicated by him with a question mark and you can see them in the picture above. Subsequently, the corresponding elements were indeed discovered: Galium, Germanium, Scandium. Thus, Dmitry Ivanovich not only systematized the elements into groups and periods, but also predicted the discovery of new, not yet known, elements.

Later, after resolving many of the topical mysteries of chemistry of that time - the discovery of new elements, the isolation of a group of noble gases together with the participation of William Ramsay, the establishment of the fact that Didymium is not an independent element at all, but is a mixture of two others - more and more new and new versions of the table, sometimes even having a non-table view at all. But we will not give them all here, but we will give only the final version, which was formed during the life of the great scientist.

Transition from atomic weights to nuclear charge.

Unfortunately, Dmitry Ivanovich did not live to see the planetary theory of the structure of the atom and did not see the triumph of Rutherford's experiments, although it was with his discoveries that a new era began in the development of the periodic law and the entire periodic system. Let me remind you that from the experiments conducted by Ernest Rutherford, it followed that the atoms of elements consist of a positively charged atomic nucleus and negatively charged electrons revolving around the nucleus. After determining the charges of the atomic nuclei of all the elements known at that time, it turned out that in the periodic system they are located in accordance with the charge of the nucleus. BUT periodic law took on a new meaning, now it began to sound like this:

"The properties of chemical elements, as well as the forms and properties of the simple substances and compounds they form, are in a periodic dependence on the magnitude of the charges of the nuclei of their atoms"

Now it became clear why some of the lighter elements were put by Mendeleev behind their heavier predecessors - the whole point is that this is how they stand in the order of the charges of their nucleus. For example, tellurium is heavier than iodine, but it is earlier in the table, because the charge of the nucleus of its atom and the number of electrons is 52, while iodine has 53. You can look at the table and see for yourself.

After the discovery of the structure of the atom and the atomic nucleus, periodic system underwent several more changes, until, finally, it reached the form already familiar to us from school, the short-period version of the periodic table.

In this table, we already know everything: 7 periods, 10 series, side and main subgroups. Also, with the time of the discovery of new elements and the filling of the table with them, elements like Actinium and Lanthanum had to be placed in separate rows, all of them were respectively named Actinides and Lanthanides. This version of the system existed for a very long time - in the world scientific community almost until the end of the 80s, the beginning of the 90s, and in our country even longer - until the 10s of this century.

A modern version of the periodic table.

However, the option that many of us went through at school actually turns out to be very confusing, and the confusion is expressed in the division of subgroups into main and secondary ones, and remembering the logic of displaying the properties of elements becomes quite difficult. Of course, despite this, many studied it, became doctors of chemical sciences, but still, in modern times, it has been replaced by a new version - a long-term one. I note that this particular option is approved by IUPAC (International Union of Pure and Applied Chemistry). Let's take a look at it.

The eight groups were replaced by eighteen, among which there is no longer any division into main and secondary, and all groups are dictated by the arrangement of electrons in the atomic shell. At the same time, they got rid of two-row and single-row periods, now all periods contain only one row. How convenient is this option? Now the periodicity of the properties of elements is viewed more clearly. The group number, in fact, indicates the number of electrons in the outer level, and therefore all the main subgroups of the old version are located in the first, second and thirteenth to eighteenth groups, and all the "former side" groups are located in the middle of the table. Thus, it is now clearly seen from the table that if this is the first group, then these are alkali metals and no copper or silver for you, and it is clear that all transit metals demonstrate well the similarity of their properties due to the filling of the d-sublevel, which affects to a lesser extent external properties, as well as lanthanides and actinides, exhibit similar properties due to only the f-sublevel being different. Thus, the whole table is divided into the following blocks: s-block, on which s-electrons are filled, d-block, p-block and f-block, with filling d, p, and f-electrons, respectively.

Unfortunately, in our country this option has been included in school textbooks only in the last 2-3 years, and even then not in all. And very wrong. What is it connected with? Well, firstly, with stagnant times in the dashing 90s, when there was no development at all in the country, not to mention the education sector, namely in the 90s, the world chemical community switched to this option. Secondly, with a slight inertia and difficulty in perceiving everything new, because our teachers are accustomed to the old, short-term version of the table, despite the fact that it is much more difficult and less convenient when studying chemistry.

Expanded version of the periodic system.

But time does not stand still, science and technology too. The 118th element of the periodic system has already been discovered, which means that the next, eighth, period of the table will soon have to be discovered. In addition, a new energy sublevel will appear: the g-sublevel. The elements of its constituents will have to be moved down the table, like lanthanides or actinides, or this table will be expanded twice more, so that it will no longer fit on an A4 sheet. Here I will give only a link to Wikipedia (see Extended Periodic System) and will not repeat the description of this option once again. Anyone who is interested can follow the link and have a look.

In this version, neither f-elements (lanthanides and actinides) nor g-elements ("elements of the future" from Nos. 121-128) are listed separately, but make the table wider by 32 cells. Also, the element Helium is placed in the second group, since it is included in the s-block.

In general, it is unlikely that future chemists will use this option, most likely the periodic table will be replaced by one of the alternatives that are already put forward by brave scientists: the Benfey system, Stewart's "Chemical Galaxy" or another option. But this will be only after the achievement of the second island of stability of chemical elements and, most likely, it will be necessary more for clarity in nuclear physics than in chemistry, but for now, the good old Dmitry Ivanovich's periodic system will suffice.

Instruction

The periodic system is a multi-storey "house" in which the a large number of apartments. Each "tenant" or in his own apartment under a certain number, which is permanent. In addition, the element has a "surname" or name, such as oxygen, boron or nitrogen. In addition to these data, each "apartment" or information such as relative atomic mass is indicated, which may have exact or rounded values.

As in any house, there are "entrances", namely groups. Moreover, in groups, elements are located on the left and right, forming . Depending on which side there are more of them, that side is called the main one. The other subgroup, respectively, will be secondary. Also in the table there are "floors" or periods. Moreover, the periods can be both large (consist of two rows) and small (they have only one row).

According to the table, you can show the structure of the atom of an element, each of which has a positively charged nucleus, consisting of protons and neutrons, as well as negatively charged electrons rotating around it. The number of protons and electrons coincides numerically and is determined in the table by the ordinal number of the element. For example, the chemical element sulfur has #16, so it will have 16 protons and 16 electrons.

To determine the number of neutrons (neutral particles also located in the nucleus), subtract its serial number from the relative atomic mass of an element. For example, iron has a relative atomic mass of 56 and an atomic number of 26. Therefore, 56 - 26 = 30 protons in iron.

The electrons are located at different distances from the nucleus, forming electronic levels. To determine the number of electronic (or energy) levels, you need to look at the number of the period in which the element is located. For example, aluminum is in period 3, so it will have 3 levels.

By the group number (but only for the main subgroup), you can determine the highest valence. For example, the elements of the first group of the main subgroup (lithium, sodium, potassium, etc.) have a valence of 1. Accordingly, the elements of the second group (beryllium, magnesium, calcium, etc.) will have a valence of 2.

You can also analyze the properties of elements using the table. From left to right, the metallic properties decrease and the non-metallic properties increase. This is clearly seen in the example of 2 periods: it begins alkali metal sodium, then the alkaline earth metal magnesium, after it the amphoteric element aluminum, then the non-metals silicon, phosphorus, sulfur and the period ends gaseous substances- chlorine and argon. In the next period, a similar dependence is observed.

From top to bottom, a pattern is also observed - metallic properties are enhanced, and non-metallic ones are weakened. That is, for example, cesium is much more active than sodium.

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Anyone who went to school remembers that one of the required subjects to study was chemistry. She could like it, or she could not like it - it does not matter. And it is likely that much knowledge in this discipline has already been forgotten and is not applied in life. However, everyone probably remembers the table of chemical elements of D. I. Mendeleev. For many, it has remained a multi-colored table, where certain letters are inscribed in each square, denoting the names of chemical elements. But here we will not talk about chemistry as such, and describe hundreds of chemical reactions and processes, but we will talk about how the periodic table appeared in general - this story will be of interest to any person, and indeed to all those who are hungry for interesting and useful information.

A little background

Back in 1668, the outstanding Irish chemist, physicist and theologian Robert Boyle published a book in which many myths about alchemy were debunked, and in which he talked about the need to search for indecomposable chemical elements. The scientist also gave a list of them, consisting of only 15 elements, but allowed the idea that there may be more elements. This became the starting point not only in the search for new elements, but also in their systematization.

One hundred years later, the French chemist Antoine Lavoisier compiled a new list, which already included 35 elements. 23 of them were later found to be indecomposable. But the search for new elements continued by scientists around the world. And leading role the famous Russian chemist Dmitry Ivanovich Mendeleev played in this process - he was the first to put forward the hypothesis that there could be a relationship between the atomic mass of elements and their location in the system.

Thanks to painstaking work and comparison of chemical elements, Mendeleev was able to discover a relationship between elements in which they can be one, and their properties are not something taken for granted, but are a periodically repeating phenomenon. As a result, in February 1869, Mendeleev formulated the first periodic law, and already in March, his report “The relationship of properties with the atomic weight of elements” was submitted to the Russian Chemical Society by the historian of chemistry N. A. Menshutkin. Then in the same year, Mendeleev's publication was published in the journal Zeitschrift fur Chemie in Germany, and in 1871 a new extensive publication of the scientist dedicated to his discovery was published by another German journal Annalen der Chemie.

Creating a Periodic Table

The main idea by 1869 had already been formed by Mendeleev, and for quite a short time, but for a long time he could not arrange it into some sort of ordered system that clearly displays what's what. In one of the conversations with his colleague A. A. Inostrantsev, he even said that everything had already worked out in his head, but he could not bring everything to the table. After that, according to Mendeleev's biographers, he began painstaking work on his table, which lasted three days without a break for sleep. All sorts of ways to organize the elements in a table were sorted out, and the work was complicated by the fact that at that time science did not yet know about all the chemical elements. But, despite this, the table was still created, and the elements were systematized.

Legend of Mendeleev's dream

Many have heard the story that D. I. Mendeleev dreamed of his table. This version was actively distributed by the aforementioned colleague of Mendeleev, A. A. Inostrantsev, as a funny story with which he entertained his students. He said that Dmitry Ivanovich went to bed and in a dream he clearly saw his table, in which all the chemical elements were arranged in the right order. After that, the students even joked that 40° vodka was discovered in the same way. But there were still real prerequisites for the sleep story: as already mentioned, Mendeleev worked on the table without sleep and rest, and Inostrantsev once found him tired and exhausted. In the afternoon, Mendeleev decided to take a break, and some time later, he woke up abruptly, immediately took a piece of paper and depicted a ready-made table on it. But the scientist himself refuted this whole story with a dream, saying: “I’ve been thinking about it for maybe twenty years, and you think: I was sitting and suddenly ... it’s ready.” So the legend of the dream may be very attractive, but the creation of the table was only possible through hard work.

Further work

In the period from 1869 to 1871, Mendeleev developed the ideas of periodicity, to which the scientific community was inclined. And one of the important stages of this process was the understanding that any element in the system should be located based on the totality of its properties in comparison with the properties of other elements. Based on this, and also based on the results of research in the change of glass-forming oxides, the chemist managed to amend the values ​​of the atomic masses of some elements, among which were uranium, indium, beryllium and others.

Of course, Mendeleev wanted to fill the empty cells that remained in the table as soon as possible, and in 1870 he predicted that they would soon be opened unknown to science chemical elements, the atomic masses and properties of which he was able to calculate. The first of these were gallium (discovered in 1875), scandium (discovered in 1879) and germanium (discovered in 1885). Then the forecasts continued to be realized, and eight more new elements were discovered, including: polonium (1898), rhenium (1925), technetium (1937), francium (1939) and astatine (1942-1943). By the way, in 1900, D. I. Mendeleev and the Scottish chemist William Ramsay came to the conclusion that the elements of the zero group should also be included in the table - until 1962 they were called inert, and after - noble gases.

Organization of the periodic system

The chemical elements in the table of D. I. Mendeleev are arranged in rows, in accordance with the increase in their mass, and the length of the rows is chosen so that the elements in them have similar properties. For example, noble gases such as radon, xenon, krypton, argon, neon, and helium do not easily react with other elements, and also have low chemical activity, which is why they are located in the far right column. And the elements of the left column (potassium, sodium, lithium, etc.) react perfectly with other elements, and the reactions themselves are explosive. To put it simply, within each column, the elements have similar properties, varying from one column to the next. All elements up to No. 92 are found in nature, and with No. 93 artificial elements begin, which can only be created in the laboratory.

In its original version, the periodic system was understood only as a reflection of the order existing in nature, and there were no explanations why everything should be that way. And only when it appeared quantum mechanics, the true meaning of the order of elements in the table became clear.

Creative Process Lessons

Speaking about what lessons of the creative process can be drawn from the entire history of the creation of the periodic table of D. I. Mendeleev, one can cite as an example the ideas of an English researcher in the field creative thinking Graham Wallace and the French scientist Henri Poincaré. Let's take them briefly.

According to Poincaré (1908) and Graham Wallace (1926), there are four main stages in creative thinking:

• Training- the stage of formulating the main task and the first attempts to solve it;
• Incubation- the stage during which there is a temporary distraction from the process, but work on finding a solution to the problem is carried out at a subconscious level;
• insight- the stage at which the intuitive solution is found. Moreover, this solution can be found in a situation that is absolutely not relevant to the task;
• Examination- the stage of testing and implementation of the solution, at which the verification of this solution and its possible further development takes place.

As we can see, in the process of creating his table, Mendeleev intuitively followed these four stages. How effective this is can be judged by the results, i.e. because the table was created. And given that its creation was a huge step forward not only for chemical science, but for the whole of humanity, the above four stages can be applied both to the implementation of small projects and to the implementation of global plans. The main thing to remember is that not a single discovery, not a single solution to a problem can be found on its own, no matter how much we want to see them in a dream and no matter how much we sleep. In order to succeed, whether it is the creation of a table of chemical elements or the development of a new marketing plan, you need to have certain knowledge and skills, as well as skillfully use your potential and work hard.

We wish you success in your endeavors and successful implementation of your plans!