Periodic table chemical elements(Mendeleev table)- classification of chemical elements that establishes the dependence various properties elements from charge atomic nucleus. The system is a graphical expression periodic law, established by the Russian chemist D.I. Mendeleev in 1869. Its original version was developed by D.I. Mendeleev in 1869-1871 and established the dependence of the properties of elements on their atomic weight (in modern terms, on atomic mass). In total, several hundred options for depicting the periodic table (analytical curves, tables, geometric shapes and so on.). In the modern version of the system, it is assumed that elements are brought together into a two-dimensional table, in which each column (group) defines the main physicochemical characteristics, and the lines represent periods that are somewhat similar to each other.
Periodic table of chemical elements by D.I. Mendeleev
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The discovery made by the Russian chemist Mendeleev played (by far) the most important role in the development of science, namely in the development of atomic-molecular science. This discovery made it possible to obtain the most understandable and easy-to-learn ideas about simple and complex chemical compounds. Only thanks to the table do we have the concepts about the elements that we use in modern world. In the twentieth century, the predictive role of the periodic system in assessing chemical properties, transuranium elements, shown by the creator of the table.
Developed in the 19th century, Mendeleev's periodic table in the interests of the science of chemistry provided a ready-made systematization of the types of atoms for the development of PHYSICS in the 20th century (physics of the atom and the atomic nucleus). At the beginning of the twentieth century, physicists, through research they established that the atomic number (also known as atomic number) is also a measure electric charge atomic nucleus of that element. And the number of the period (i.e., horizontal series) determines the number of electron shells of the atom. It also turned out that the number of the vertical row of the table determines the quantum structure outer shell element (thus, elements of the same series are due to the similarity of chemical properties).
The discovery of the Russian scientist marked new era in the history of world science, this discovery not only made it possible to make a huge leap in chemistry, but was also invaluable for a number of other areas of science. The periodic table provided a coherent system of information about the elements, based on it, it became possible to draw scientific conclusions, and even anticipate some discoveries.
Periodic tableOne of the features periodic table Mendeleev, is that the group (column in the table) has more significant expressions of the periodic trend than for periods or blocks. Nowadays, the theory of quantum mechanics and atomic structure explains the group essence of elements by the fact that they have the same electronic configurations of valence shells, and as a result, elements that are located within the same column have very similar (identical) features of the electronic configuration, with similar chemical properties. There is also a clear tendency for a stable change in properties as the atomic mass increases. It should be noted that in some areas of the periodic table (for example, in blocks D and F), horizontal similarities are more noticeable than vertical ones.
The periodic table contains groups that are assigned serial numbers from 1 to 18 (from left to right), according to the international group naming system. In the past, Roman numerals were used to identify groups. In America, there was a practice of placing after the Roman numeral, the letter “A” when the group is located in blocks S and P, or the letter “B” for groups located in block D. The identifiers used at that time are the same as the latter the number of modern indexes in our time (for example, the name IVB corresponds to elements of group 4 in our time, and IVA is the 14th group of elements). IN European countries At that time, a similar system was used, but here, the letter “A” referred to groups up to 10, and the letter “B” - after 10 inclusive. But groups 8,9,10 had ID VIII, as one triple group. These group names ceased to exist after the 1988 new system IUPAC notation, which is still used today.
Many groups received unsystematic names of a herbal nature (for example, “alkaline earth metals”, or “halogens”, and other similar names). Groups 3 to 14 did not receive such names, due to the fact that they to a lesser extent are similar to each other and have less compliance with vertical patterns; they are usually named either by number or by the name of the first element of the group (titanium, cobalt, etc.).
Chemical elements belonging to the same group of the periodic table show certain trends in electronegativity, atomic radius and ionization energy. In one group, from top to bottom, the radius of the atom increases as the energy levels are filled, the valence electrons of the element move away from the nucleus, while the ionization energy decreases and the bonds in the atom weaken, which simplifies the removal of electrons. Electronegativity also decreases, this is a consequence of the fact that the distance between the nucleus and valence electrons increases. But there are also exceptions to these patterns, for example, electronegativity increases, instead of decreasing, in group 11, in the direction from top to bottom. There is a line in the periodic table called “Period”.
Among the groups, there are those in which horizontal directions are more significant (unlike others in which higher value have vertical directions), such groups include block F, in which lanthanides and actinides form two important horizontal sequences.
Elements show certain patterns in atomic radius, electronegativity, ionization energy, and electron affinity energy. Due to the fact that for each subsequent element the number of charged particles increases, and electrons are attracted to the nucleus, the atomic radius decreases from left to right, along with this the ionization energy increases, and as the bond in the atom increases, the difficulty of removing an electron increases. Metals located on the left side of the table are characterized by a lower electron affinity energy indicator, and accordingly, on the right side the electron affinity energy indicator is higher for non-metals (not counting the noble gases).
Different regions of the periodic table, depending on which shell of the atom the last electron is located on, and in view of the importance of the electron shell, are usually described as blocks.
The S-block includes the first two groups of elements (alkali and alkaline earth metals, hydrogen and helium).
The P-block includes the last six groups, from 13 to 18 (according to IUPAC, or according to the system adopted in America - from IIIA to VIIIA), this block also includes all metalloids.
Block - D, groups 3 to 12 (IUPAC, or IIIB to IIB in American), this block includes all transition metals.
Block - F, is usually placed outside the periodic table, and includes lanthanides and actinides.
Anyone who went to school remembers that one of the compulsory subjects to study was chemistry. You might like her, or you might not like her - it doesn't matter. And it is likely that much knowledge in this discipline has already been forgotten and is not used in life. However, everyone probably remembers D.I. Mendeleev’s table of chemical elements. For many, it has remained a multi-colored table, where certain letters are written in each square, indicating 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 tell you how the periodic table appeared in the first place - this story will be interesting 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 discussed the need to search for indecomposable chemical elements. The scientist also gave a list of them, consisting of only 15 elements, but admitted 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.
A 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 main role The famous Russian chemist Dmitry Ivanovich Mendeleev played a role 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 the connection between the elements, in which they can be one, and their properties are not something taken for granted, but represent a periodically repeating phenomenon. As a result, in February 1869, Mendeleev formulated the first periodic law, and already in March his report “Relationship of properties with the atomic weight of elements” was presented 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, another German journal “Annalen der Chemie” published a new extensive publication by the scientist dedicated to his discovery.
Creating the periodic table
By 1869, the main idea had already been formed by Mendeleev, and quite quickly. a short time, but for a long time he could not arrange it into any orderly system that would clearly display what was what. In one of the conversations with his colleague A.A. Inostrantsev, he even said that he had everything already worked out in his head, but he couldn’t put everything into a table. After this, according to Mendeleev’s biographers, he began painstaking work on his table, which lasted three days without breaks for sleep. They tried all sorts of ways to organize elements into a table, and the work was also 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.
The legend of Mendeleev's dream
Many have heard the story that D.I. Mendeleev dreamed about his table. This version was actively disseminated by the aforementioned Mendeleev’s associate 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 clearly saw his table, in which all the chemical elements were arranged in the right order. After this, the students even joked that 40° vodka was discovered in the same way. But there were still real prerequisites for the story with sleep: as already mentioned, Mendeleev worked on the table without sleep or rest, and Inostrantsev once found him tired and exhausted. During the day, Mendeleev decided to take a short rest, and some time later, he woke up abruptly, immediately took a piece of paper and drew a ready-made table on it. But the scientist himself refuted this whole story with the dream, saying: “I’ve been thinking about it, maybe for 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
Between 1869 and 1871, Mendeleev developed the ideas of periodicity toward which the scientific community was inclined. And one of important stages This process was the understanding that any element in the system should have, based on the totality of its properties in comparison with the properties of other elements. Based on this, and also relying on the results of research into changes in glass-forming oxides, the chemist was able to make corrections to the values of the atomic masses of some elements, including uranium, indium, beryllium and others.
Mendeleev, of course, wanted to quickly fill the empty cells that remained in the table, and in 1870 he predicted that chemical elements unknown to science would soon be discovered, 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 table should also include elements of group zero - until 1962 they were called inert gases, and after that - noble gases.
Organization of the periodic table
Chemical elements in D.I. Mendeleev’s table are arranged in rows, in accordance with the increase in their mass, and the length of the rows is selected so that the elements in them have similar properties. For example, noble gases such as radon, xenon, krypton, argon, neon and helium are difficult to react with other elements and also have low chemical reactivity, which is why they are located in the far right column. And the elements in the left column (potassium, sodium, lithium, etc.) react well with other elements, and the reactions themselves are explosive. Simply put, within each column, elements have similar properties that vary from one column to the next. All elements up to No. 92 are found in nature, and from No. 93 artificial elements begin, which can only be created in laboratory conditions.
In its original version, the periodic system was understood only as a reflection of the order existing in nature, and there were no explanations as to why everything should be this way. And only when she appeared quantum mechanics, the true meaning of the order of elements in the table became clear.
Lessons in the creative process
Talking about what lessons creative process can be extracted from the entire history of the creation of the periodic table by D.I. Mendeleev; one can cite as an example the ideas of the English researcher in the field of creative thinking Graham Wallace and the French scientist Henri Poincaré. Let's give them briefly.
According to the studies of Poincaré (1908) and Graham Wallace (1926), there are four main stages of creative thinking:
- Preparation– the stage of formulating the main problem and the first attempts to solve it;
- Incubation– a stage during which there is a temporary distraction from the process, but work on finding a solution to the problem is carried out on a subconscious level;
- Insight– the stage at which the intuitive solution is located. Moreover, this solution can be found in a situation that is completely unrelated to the problem;
- Examination– the stage of testing and implementation of a solution, at which this solution is tested and its possible further development.
As we can see, in the process of creating his table, Mendeleev intuitively followed precisely these four stages. How effective this is can be judged by the results, i.e. by the fact that the table was created. And given that its creation was a huge step forward not only for chemical science, but also for all 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 for something to work out, it doesn’t matter whether it’s creating a table of chemical elements or developing 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!
The periodic table is one of greatest discoveries humanity, which made it possible to organize knowledge about the world around us and discover new chemical elements. It is necessary for schoolchildren, as well as for anyone interested in chemistry. Besides, this scheme is indispensable in other areas of science.
This diagram contains everything known to man elements, and they are grouped depending on atomic mass and serial number
. These characteristics affect the properties of the elements. In total, there are 8 groups in the short version of the table; the elements included in one group have very similar properties. The first group contains hydrogen, lithium, potassium, copper, whose Latin pronunciation in Russian is cuprum. And also argentum - silver, cesium, gold - aurum and francium. The second group contains beryllium, magnesium, calcium, zinc, followed by strontium, cadmium, barium, and the group ends with mercury and radium.
The third group includes boron, aluminum, scandium, gallium, followed by yttrium, indium, lanthanum, and the group ends with thallium and actinium. The fourth group begins with carbon, silicon, titanium, continues with germanium, zirconium, tin and ends with hafnium, lead and rutherfordium. The fifth group contains elements such as nitrogen, phosphorus, vanadium, below are arsenic, niobium, antimony, then comes tantalum, bismuth and completes the group with dubnium. The sixth begins with oxygen, followed by sulfur, chromium, selenium, then molybdenum, tellurium, then tungsten, polonium and seaborgium.
In the seventh group, the first element is fluorine, followed by chlorine, manganese, bromine, technetium, followed by iodine, then rhenium, astatine and bohrium. The last group is the most numerous. It includes gases such as helium, neon, argon, krypton, xenon and radon. This group also includes metals iron, cobalt, nickel, rhodium, palladium, ruthenium, osmium, iridium, and platinum. Next come hannium and meitnerium. The elements that form the actinide series and lanthanide series. They have similar properties to lanthanum and actinium.
This scheme includes all types of elements that are divided into 2 large groups – metals and non-metals, having different properties. How to determine whether an element belongs to one group or another will be helped by a conventional line that must be drawn from boron to astatine. It should be remembered that such a line can only be drawn in full version tables. All elements that are above this line and are located in the main subgroups are considered non-metals. And those below, in the main subgroups, are metals. Metals are also substances found in side subgroups. There are special pictures and photos in which you can familiarize yourself in detail with the position of these elements. It is worth noting that those elements that are on this line exhibit the same properties of both metals and non-metals.
A separate list is made up of amphoteric elements, which have dual properties and can form 2 types of compounds as a result of reactions. At the same time, they manifest both basic and acid properties. The predominance of certain properties depends on the reaction conditions and substances with which the amphoteric element reacts.
It is worth noting that this scheme, in its traditional design of good quality, is colored. Wherein different colors for ease of orientation are indicated main and secondary subgroups. Elements are also grouped depending on the similarity of their properties.
However, nowadays, along with the color scheme, the black and white periodic table of Mendeleev is very common. This type is used for black and white printing. Despite its apparent complexity, working with it is just as convenient if you take into account some of the nuances. So, in this case, you can distinguish the main subgroup from the secondary one by differences in shades that are clearly visible. In addition, in the color version, elements with the presence of electrons on different layers are designated different colors.
It is worth noting that in a single-color design it is not very difficult to navigate the scheme. For this purpose, the information indicated in each individual cell of the element will be sufficient.
The Unified State Exam today is the main type of test at the end of school, which means that preparation for it must be given Special attention. Therefore, when choosing final exam in chemistry, you need to pay attention to materials that can help you pass it. As a rule, schoolchildren are allowed to use some tables during the exam, in particular, the periodic table in good quality. Therefore, in order for it to bring only benefits during testing, attention should be paid in advance to its structure and the study of the properties of the elements, as well as their sequence. You also need to learn use the black and white version of the table so as not to encounter some difficulties in the exam.
In addition to the main table characterizing the properties of elements and their dependence on atomic mass, there are other diagrams that can help in the study of chemistry. For example, there are tables of solubility and electronegativity of substances. The first can be used to determine how soluble a particular compound is in water at normal temperature. In this case, anions are located horizontally - negatively charged ions, and cations - that is, positively charged ions - are located vertically. To find out degree of solubility of one or another compound, it is necessary to find its components using the table. And at the place of their intersection there will be the necessary designation.
If it is the letter “p”, then the substance is completely soluble in water under normal conditions. If the letter “m” is present, the substance is slightly soluble, and if the letter “n” is present, it is almost insoluble. If there is a “+” sign, the compound does not form a precipitate and reacts with the solvent without residue. If a "-" sign is present, it means that such a substance does not exist. Sometimes you can also see the “?” sign in the table, then this means that the degree of solubility of this compound is not known for certain. Electronegativity of elements can vary from 1 to 8; there is also a special table to determine this parameter.
Another one useful table– activity series of metals. All metals are located in it according to increasing degrees of electrochemical potential. The series of metal voltages begins with lithium and ends with gold. It is believed that the further to the left a metal occupies a place in a given row, the more active it is in chemical reactions. Thus, the most active metal Lithium is considered an alkaline metal. The list of elements also contains hydrogen towards the end. It is believed that the metals located after it are practically inactive. These include elements such as copper, mercury, silver, platinum and gold.
Periodic table pictures in good quality
This scheme is one of the largest achievements in the field of chemistry. Wherein there are many types of this table – short version, long, as well as extra-long. The most common is a short table; it is also common to see long version scheme. It is worth noting that the short version of the circuit is not currently recommended for use by IUPAC.
In total there were More than a hundred types of tables have been developed, differing in presentation, form and graphical presentation. They are used in different areas science, or are not applied at all. Currently, new circuit configurations continue to be developed by researchers. The main option is either a short or long circuit in excellent quality.
Knowing the formulation of the periodic law and using D.I. Mendeleev’s periodic system of elements, one can characterize any chemical element and its compounds. It is convenient to put together such a characteristic of a chemical element according to plan.
I. Symbol of a chemical element and its name.
II. The position of the chemical element in periodic table elements D.I. Mendeleev:
- serial number;
- period number;
- group number;
- subgroup (main or secondary).
III. Structure of an atom of a chemical element:
- charge of the nucleus of an atom;
- relative atomic mass of a chemical element;
- number of protons;
- number of electrons;
- number of neutrons;
- number of electronic levels in an atom.
IV. Electronic and electron-graphic formulas of an atom, its valence electrons.
V. Type of chemical element (metal or non-metal, s-, p-, d- or f-element).
VI. Formulas of the highest oxide and hydroxide of a chemical element, characteristics of their properties (basic, acidic or amphoteric).
VII. Comparison of the metallic or non-metallic properties of a chemical element with the properties of neighboring elements by period and subgroup.
VIII. The maximum and minimum oxidation state of an atom.
For example, we will provide a description of a chemical element with serial number 15 and its compounds according to their position in D.I. Mendeleev’s periodic table of elements and the structure of the atom.
I. We find in D.I. Mendeleev’s table a cell with the number of a chemical element, write down its symbol and name.
Chemical element number 15 is Phosphorus. Its symbol is R.
II. Let us characterize the position of the element in D.I. Mendeleev’s table (period number, group, subgroup type).
Phosphorus is found in main subgroup Group V, in the 3rd period.
III. We will provide a general description of the composition of an atom of a chemical element (nuclear charge, atomic mass, number of protons, neutrons, electrons and electronic levels).
The nuclear charge of the phosphorus atom is +15. The relative atomic mass of phosphorus is 31. The nucleus of an atom contains 15 protons and 16 neutrons (31 - 15 = 16). The phosphorus atom has three energy levels containing 15 electrons.
IV. We compose the electronic and electron-graphic formulas of the atom, marking its valence electrons.
The electronic formula of the phosphorus atom is: 15 P 1s 2 2s 2 2p 6 3s 2 3p 3.
Electron graphic formula of the outer level of the phosphorus atom: on the third energy level on the 3s sublevel there are two electrons (two arrows having the opposite direction are written in one cell), on three p sublevels there are three electrons (one arrow having the same direction is written in each of the three cells).
Valence electrons are electrons of the outer level, i.e. 3s2 3p3 electrons.
V. Determine the type of chemical element (metal or non-metal, s-, p-, d-or f-element).
Phosphorus is a non-metal. Since the latter sublevel in the phosphorus atom, which is filled with electrons, is the p-sublevel, Phosphorus belongs to the family of p-elements.
VI. We compose formulas of higher oxide and hydroxide of phosphorus and characterize their properties (basic, acidic or amphoteric).
Higher phosphorus oxide P 2 O 5 exhibits properties acid oxide. Hydroxide corresponding higher oxide, H 3 PO 4, exhibits the properties of an acid. Let us confirm these properties with equations of the types of chemical reactions:
P 2 O 5 + 3 Na 2 O = 2Na 3 PO 4
H 3 PO 4 + 3NaOH = Na 3 PO 4 + 3H 2 O
VII. Let's compare the non-metallic properties of phosphorus with the properties of neighboring elements by period and subgroup.
Phosphorus' subgroup neighbor is nitrogen. Phosphorus' period neighbors are silicon and sulfur. The nonmetallic properties of atoms of chemical elements of the main subgroups with increasing atomic number increase in periods and decrease in groups. Therefore, the non-metallic properties of phosphorus are more pronounced than those of silicon and less pronounced than those of nitrogen and sulfur.
VIII. We determine the maximum and minimum oxidation state of the phosphorus atom.
The maximum positive oxidation state for chemical elements of the main subgroups is equal to the group number. Phosphorus is in the main subgroup of the fifth group, so the maximum oxidation state of phosphorus is +5.
The minimum oxidation state for nonmetals in most cases is the difference between the group number and the number eight. Thus, the minimum oxidation state of phosphorus is -3.
MENDELEEV'S PERIODIC TABLE
The construction of Mendeleev's periodic table of chemical elements corresponds to the characteristic periods of number theory and orthogonal bases. The addition of Hadamard matrices with matrices of even and odd orders creates a structural basis of nested matrix elements: matrices of the first (Odin), second (Euler), third (Mersenne), fourth (Hadamard) and fifth (Fermat) orders.
It is easy to see that there are 4 orders k Hadamard matrices correspond to inert elements with an atomic mass that is a multiple of four: helium 4, neon 20, argon 40 (39.948), etc., but also the basics of life and digital technology: carbon 12, oxygen 16, silicon 28, germanium 72.
It seems that with Mersenne matrices of orders 4 k–1, on the contrary, everything active, poisonous, destructive and corrosive is connected. But these are also radioactive elements - energy sources, and lead 207 (the final product, poisonous salts). Fluorine, of course, is 19. The orders of the Mersenne matrices correspond to the sequence of radioactive elements called the actinium series: uranium 235, plutonium 239 (an isotope that is a more powerful source of atomic energy than uranium), etc. These are also alkali metals lithium 7, sodium 23 and potassium 39.
Gallium – atomic weight 68
Orders 4 k–2 Euler matrices (double Mersenne) correspond to nitrogen 14 (the basis of the atmosphere). Table salt is formed by two “mersenne-like” atoms of sodium 23 and chlorine 35; together this combination is characteristic of Euler matrices. The more massive chlorine with a weight of 35.4 falls just short of the Hadamard dimension of 36. Table salt crystals: a cube (! i.e. a docile character, Hadamards) and an octahedron (more defiant, this is undoubtedly Euler).
IN atomic physics transition iron 56 - nickel 59, this is the boundary between elements that provide energy during the synthesis of a larger nucleus ( H-bomb) and decay (uranium). Order 58 is famous for the fact that not only does it not have analogues of Hadamard matrices in the form of Belevich matrices with zeros on the diagonal, it also does not have many weighted matrices - the nearest orthogonal W(58,53) has 5 zeros in each column and row (deep gap ).
In the series corresponding to the Fermat matrices and their substitutions of order 4 k+1, by the will of fate it costs Fermium 257. You can’t say anything, an exact hit. Here there is gold 197. Copper 64 (63.547) and silver 108 (107.868), symbols of electronics, do not, as can be seen, reach gold and correspond to more modest Hadamard matrices. Copper, with its atomic weight not far from 63, is chemically active - its green oxides are well known.
Boron crystals under high magnification
WITH golden ratio boron is bound - the atomic mass among all other elements is closest to 10 (more precisely 10.8, the proximity of the atomic weight to odd numbers also has an effect). Boron is a rather complex element. Boron plays an intricate role in the history of life itself. The structure of the framework in its structures is much more complex than in diamond. Unique type chemical bond, which allows boron to absorb any impurity, is very poorly understood, although research related to it, a large number of scientists have already received Nobel Prizes. The boron crystal shape is an icosahedron, with five triangles forming the apex.
The mystery of Platinum. The fifth element is, without a doubt, noble metals such as gold. Superstructure over Hadamard dimension 4 k, 1 large.
Stable isotope uranium 238
Let us remember, however, that Fermat numbers are rare (the closest is 257). Crystals of native gold have a shape close to a cube, but the pentagram also sparkles. Its nearest neighbor, platinum, a noble metal, is less than 4 atomic weight away from gold 197. Platinum has an atomic weight not of 193, but slightly higher, 194 (the order of the Euler matrices). It's a small thing, but it brings her into the camp of somewhat more aggressive elements. It is worth remembering, in connection with its inertness (dissolves, perhaps, in aqua regia), platinum is used as an active catalyst chemical processes.
Spongy platinum at room temperature ignites hydrogen. Platinum’s character is not at all peaceful; iridium 192 (a mixture of isotopes 191 and 193) behaves more peacefully. It's more like copper, but with the weight and character of gold.
Between neon 20 and sodium 23 there is no element with atomic weight 22. Of course, atomic weights are an integral characteristic. But among the isotopes, in turn, there is also an interesting correlation of properties with the properties of numbers and the corresponding matrices of orthogonal bases. As nuclear fuel The most widely used isotope is uranium 235 (order of Mersenne matrices), in which a self-sustaining chain chain is possible nuclear reaction. In nature, this element occurs in the stable form uranium 238 (Eulerian matrix order). There is no element with atomic weight 13. As for chaos, the limited number of stable elements of the periodic table and the difficulty of finding high-order level matrices due to the barrier observed in thirteenth-order matrices correlate.
Isotopes of chemical elements, island of stability
