D in the periodic table. Periodic system of Mendeleev

He drew on the work of Robert Boyle and Antoine Lavouzier. The first scientist advocated the search for indecomposable chemical elements. 15 of those Boyle listed back in 1668.

Lavuzier added 13 more to them, but a century later. The search dragged on because there was no coherent theory of the connection between the elements. Finally, Dmitry Mendeleev entered the "game". He decided that there is a connection between the atomic mass of substances and their place in the system.

This theory allowed the scientist to discover dozens of elements without discovering them in practice, but in nature. This was placed on the shoulders of posterity. But now it's not about them. Let's dedicate the article to the great Russian scientist and his table.

The history of the creation of the periodic table

periodic table began with the book "Relationship of properties with the atomic weight of the elements." The work was issued in the 1870s. At the same time, the Russian scientist spoke to the chemical society of the country and sent the first version of the table to colleagues from abroad.

Before Mendeleev, 63 elements were discovered by various scientists. Our compatriot began by comparing their properties. First of all, he worked with potassium and chlorine. Then, he took up the group of metals of the alkaline group.

The chemist got a special table and element cards to lay them out like solitaire, looking for the right matches and combinations. As a result, an insight came: - the properties of the components depend on the mass of their atoms. So, elements of the periodic table lined up in ranks.

The discovery of the maestro of chemistry was the decision to leave voids in these ranks. The periodicity of the difference between atomic masses led the scientist to assume that not all elements are known to mankind yet. The gaps in weight between some of the "neighbors" were too large.

So, periodic table of Mendeleev became like a chessboard, with an abundance of "white" cells. Time has shown that they really were waiting for their "guests". They, for example, became inert gases. Helium, neon, argon, krypton, radioact and xenon were discovered only in the 30s of the 20th century.

Now about myths. It is widely believed that periodic table of chemistry appeared to him in a dream. These are the intrigues of university teachers, more precisely, one of them - Alexander Inostrantsev. This is a Russian geologist who lectured at the St. Petersburg University of Mining.

Inostrantsev knew Mendeleev and visited him. Once, exhausted by the search, Dmitry fell asleep right in front of Alexander. He waited until the chemist wakes up and saw how Mendeleev grabs a piece of paper and writes down the final version of the table.

In fact, the scientist simply did not have time to do this before Morpheus captured him. However, Inostrantsev wanted to amuse his students. Based on what he saw, the geologist came up with a bike, which grateful listeners quickly spread to the masses.

Features of the periodic table

Since the first version in 1969 ordinal periodic table improved many times. So, with the discovery of noble gases in the 1930s, it was possible to derive a new dependence of the elements - on their serial numbers, and not on the mass, as the author of the system stated.

The concept of "atomic weight" was replaced by "atomic number". It was possible to study the number of protons in the nuclei of atoms. This number is the serial number of the element.

Scientists of the 20th century also studied the electronic structure of atoms. It also affects the periodicity of elements and is reflected in later editions. periodic tables. A photo The list shows that the substances in it are arranged as the atomic weight increases.

The fundamental principle was not changed. Mass increases from left to right. At the same time, the table is not single, but divided into 7 periods. Hence the name of the list. Period is a horizontal row. Its beginning is typical metals, the end is elements with non-metallic properties. The decline is gradual.

There are big and small periods. The first ones are at the beginning of the table, there are 3 of them. It opens a list with a period of 2 elements. Following are two columns, in which there are 8 items. The remaining 4 periods are large. The 6th is the longest, it has 32 elements. In the 4th and 5th there are 18 of them, and in the 7th - 24.

Can be counted how many elements in the table Mendeleev. There are 112 titles in total. Names. There are 118 cells, but there are variations of the list with 126 fields. There are still empty cells for undiscovered elements that do not have names.

Not all periods fit on one line. Large periods consist of 2 rows. The amount of metals in them outweighs. Therefore, the bottom lines are completely devoted to them. A gradual decrease from metals to inert substances is observed in the upper rows.

Pictures of periodic table divided vertically. This is groups in the periodic table, there are 8 of them. Elements similar in chemical properties are arranged vertically. They are divided into main and secondary subgroups. The latter begin only from the 4th period. The main subgroups also include elements of small periods.

The essence of the periodic table

Names of elements in the periodic table is 112 positions. The essence of their arrangement in a single list is the systematization of primary elements. They began to fight over this even in ancient times.

Aristotle was one of the first to understand what everything that exists was made of. He took as a basis the properties of substances - cold and heat. Empidocles singled out 4 fundamental principles according to the elements: water, earth, fire and air.

Metals in the periodic table, like other elements, are the very fundamental principles, but from a modern point of view. The Russian chemist managed to discover most of the components of our world and to suggest the existence of still unknown primary elements.

It turns out that pronunciation of the periodic table- voicing a certain model of our reality, decomposing it into components. However, learning them is not easy. Let's try to make the task easier by describing a couple of effective methods.

How to learn the periodic table

Let's start with the modern method. Computer scientists have developed a number of flash games that help memorize Mendeleev's list. Project participants are offered to find elements by different options, for example, name, atomic mass, letter designation.

The player has the right to choose the field of activity - only part of the table, or all of it. In our will, also, exclude the names of elements, other parameters. This complicates the search. For the advanced, a timer is also provided, that is, training is carried out at speed.

Game conditions make learning element numbers in the periodic table not boring, but entertaining. Excitement wakes up, and it becomes easier to systematize knowledge in the head. Those who do not accept computer flash projects offer a more traditional way of memorizing a list.

It is divided into 8 groups, or 18 (according to the 1989 edition). For ease of remembering, it is better to create several separate tables, rather than working on a whole version. Visual images matched to each of the elements also help. Rely on your own associations.

So, iron in the brain can be correlated, for example, with a nail, and mercury with a thermometer. The name of the element is unfamiliar? We use the method of suggestive associations. , for example, we will compose from the beginnings of the words "taffy" and "speaker".

Characteristics of the periodic table don't study in one sitting. Lessons are recommended for 10-20 minutes a day. It is recommended to start by remembering only the basic characteristics: the name of the element, its designation, atomic mass and serial number.

Schoolchildren prefer to hang the periodic table above the desktop, or on the wall, which is often looked at. The method is good for people with a predominance of visual memory. Data from the list is involuntarily remembered even without cramming.

This is also taken into account by teachers. As a rule, they do not force you to memorize the list, they allow you to look at it even on the control ones. Constantly looking at the table is tantamount to the effect of printing on the wall, or writing cheat sheets before exams.

Starting the study, let us recall that Mendeleev did not immediately remember his list. Once, when the scientist was asked how he opened the table, the answer was: “I’ve been thinking about it for maybe 20 years, but you think: I sat and, suddenly, it’s ready.” The periodic system is painstaking work that cannot be mastered in a short time.

Science does not tolerate haste, because it leads to delusions and annoying mistakes. So, at the same time as Mendeleev, the table was compiled by Lothar Meyer. However, the German did not finish the list a bit and was not convincing in proving his point of view. Therefore, the public recognized the work of the Russian scientist, and not his fellow chemist from Germany.

More than 400 variants of tables of the periodic system are known, differing in the placement of individual groups of analogue elements, in the way the periodic law is displayed. In some of them, the group of "inert" gases is located on the right side (these elements end the periods in the system), in others - on the left side (they begin periods), in the third - in the middle of the table. There are tables where the elements are not arranged in the order of filling the electronic levels in atoms, but in the order of sequential arrangement on the left side of the table of groups of s- and p-elements, on the right side of all groups of d-elements, and then f-elements. Variants are known in which the elements of the first period are located at the bottom of the table, and above them are the elements of subsequent periods, which symbolizes the gradual complication of the electron shell of atoms. The authors of a number of tables divide the groups of elements into 3 or 4 subgroups, introducing f-elements into these "additional" subgroups.

However, most of these tables, emphasizing the periodicity of changes in certain properties of elements and their compounds, do not introduce anything fundamentally new into the design of the periodic system. The change in the properties of the elements is associated with the structure of the electron shell of the atom, more precisely, with the capacity of the electronic levels equal to 8, 18 and 32. From here, naturally, three main variants of the cellular image of the system of elements follow, arranged in order of increasing charge of the atomic nucleus or the number of electrons in its shell. Tables, depending on which 8-, 18- or 32-element period is the basis for their construction, are divided into 8-, 18- and 32-cell.

We have already considered the thirty-two-cell table (see Table 26) - this is a long-period table. The advantages of this natural form of the table have been noted above. Of course, this form is less compact than other forms of the table, but there is no reason to consider this a disadvantage of the table. A small number of scientists refer to the shortcomings of this table that "allegedly" it breaks the connection between the elements-analogues of the main and secondary subgroups. Such an opinion cannot be considered justified, since, from the point of view of the structure of the atom, analogous elements should be characterized by the same value of the configuration index, which is fully implemented in this version of the table (the exceptions are the configuration indices of lanthanum and actinium, but this will be discussed in detail below).

The semi-long table (Table 33) is eighteen-celled. In such a table, 14 f-elements of the sixth period - lanthanides (occupying places 58-71) and 14 f-elements of the seventh period - actinides (occupying places 90-103) are placed in separate lines below the table. By this method, the authors want to make the table more compact and bring the elements of the IIIB and IVB groups closer together. Such a table is, as it were, a classification of s-, p- and d-elements; f-elements are removed from the general table and are considered separately (the families of lanthanides and actinides).

In this table, there are two gaps in the arrangement of elements by serial numbers: after the 57th element, the 72nd element is placed, and after the 89th, the 104th element. This gap should always be kept in mind, since it does not allow one to logically use the shift rule when considering radioactive decay processes leading to the mutual transition of atomic nuclei from 57 to 58, from 71 to 72, from 89 to 90 and from 103 to 104 or vice versa. In the chemical aspect, this table is inconvenient in that it is difficult to trace the reason for the difference in the properties of elements with numbers 72-80 from the properties of elements 40-48 located directly under each other. When considering the long-period table (see Table 26), these reasons become clear. Atoms of elements 72-80, standing behind the lanthanides in the periodic table, are affected by lanthanide compression * , which results in an increase in ionization potentials, a weakening of the reducing properties of elements and a sharp increase in the density of elementary substances. This important circumstance revealing the nature of d-elements, in our opinion, cannot be neglected in favor of a more compact form of the table.

* (Decreasing the radius of an atom due to an increase in the attraction of external electrons with an increase in the charge of the nucleus, which occurs when the internal f-sublevel is built up.)

An eight-cell table, a short form of the periodic system, is most often drawn up in the following three versions: 1) lanthanides and actinides are placed at the bottom of the table, all d-elements are included in the groups of s- and p-elements of the group are divided into main and secondary subgroups (Table 34 ); 2) all elements are divided into 9 groups, including zero, consisting of two subgroups, except for VIII- and 0-groups (the latter have one subgroup each); lanthanides and actinides are included in periods VI and VII (Table 35) and 3) all f-elements are placed inside the system, the lanthanide family is divided into two "subfamilies" of seven elements each, with some shift of cells away from the main cells of element groups ; the triads of iron, ruthenium and osmium are placed on the left side of the table without group numbering (Table 36).

All these and other similar variants of the eight-cell table are compact, but they include s- and p-, s- and d-, p- and d-elements, the atoms of which differ in their electronic configuration and sharply differ in the values of configuration indices.

The multi-color version of the table of the periodic table of elements of D. I. Mendeleev, published in the form of a postcard, by the publishing house "Chemistry" is much more visual. In it, the s-elements are colored red, the p-elements yellow, the d-elements blue, and the f-elements black. In groups I and II, s-elements form the main or A-subgroups, d-elements form side or B-subgroups; in III-VIII periods, the main (A) subgroups are formed by p-elements, and the secondary (B) subgroups are formed by d-elements; f-elements (lanthanides and actinides) are placed at the bottom of the table, in separate rows. This version of the table takes into account all the previously considered arguments in favor of the arrangement of individual elements into groups in accordance with the structure of their atoms and properties. So, hydrogen is placed in the VIIA-group (but put in brackets and in the group IA, as if recalling its certain similarity with monovalent metals); Fe, Ru, and Os are located in group VIIIB, while Co, Ni, Rh, Pd, and Ir, Pt are removed from it; noble gases are placed in the VIIIA-group and, as it were, complete the periods in the table.

However, in this table, as in all eight-cell tables in general, the emphasis is on the analogy of elements along the vertical - the similarity of elements in terms of maximum valence, that is, in terms of a property that, as shown above, does not change regularly. For example, it is enough to compare all the properties and physicochemical characteristics of chlorine and manganese to be convinced of their sharp difference (the only analogy is the formation of heptavalent compounds). In terms of chemical nature, manganese is more similar to its period neighbors, i.e., chromium and iron, than to chlorine, and in this case the horizontal analogy dominates the vertical analogy.

In conclusion, we can say that all three forms of the system: long, half-long and short - can be used to display the periodic law. Each form has its own advantages and disadvantages. However, the connection between the nature of an element and the structure of the electron shell of atoms is most fully and unambiguously revealed by the long form of the system. The study of the periodic change in the properties of elements based on the electronic structures of atoms brought unprecedented development to chemical science, and it is not by chance that Academician L.V. Pisarzhevsky called this stage in the development of chemistry the electronic stage.

Currently published tables of the periodic system, including the "hypothetical" eighth and ninth periods (Seaborg, Taube, Gol'danskii), which contain 50 elements, i.e. 18 elements more than in the sixth and seventh periods. The eighth period begins with the element with the serial number 119 - ekafranzion and ends with the element with the serial number 168 - dviradone. Dviradone, by its chemical nature, should be an analogue of noble gases. In the ninth period, the first element - dvifrancium has the serial number 169, and the last - triradon, or eka-ekaradon - 218. In the last two periods, new types of elements related to g-elements should appear, since atoms have 18 elements of each period the g-sublevel (l = 4) will be built up, the maximum capacity of which is equal to 18 . New 5g-elements located in the 8th period, V. I. Gol'danskii proposed to call octadecanides.

It is difficult to say when the synthesis of unknown elements will be carried out (Z > 105), and it is unlikely that many of them will be obtained, since the nuclei of these elements are extremely unstable, but the possibility of synthesizing elements 114 and 126 is already being discussed in the literature (see below). ).

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The periodic system of chemical elements is a classification of chemical elements based on certain features of the structure of atoms of chemical elements. It was compiled on the basis of the Periodic Law, discovered in 1869 by D. I. Mendeleev. At that time, the Periodic system included 63 chemical elements and differed in appearance from the modern one. Now the Periodic system includes about one hundred and twenty chemical elements.

The periodic system is compiled in the form of a table in which the chemical elements are arranged in a certain order: as their atomic masses increase. Now there are many types of images of the Periodic system. The most common is an image in the form of a table with the arrangement of elements from left to right.

All chemical elements in the Periodic system are grouped into periods and groups. The periodic system includes seven periods and eight groups. Periods are called horizontal rows of chemical elements, in which the properties of elements change from typical metallic to non-metallic. Vertical columns of chemical elements that contain elements with similar chemical properties form groups of chemical elements.

The first, second and third periods are called small because they contain a small number of elements (the first - two elements, the second and third - eight elements each). Elements of the second and third periods are called typical, their properties regularly change from a typical metal to an inert gas.

All other periods are called large (the fourth and fifth contain 18 elements each, the sixth - 32 and the seventh - 24 elements). A special similarity of properties is shown by elements located inside large periods, at the end of each even row. These are the so-called triads: Ferum - Cobalt - Nikol, which form the iron family, and two others: Ruthenium - Rhodium - Palladium and Osmium - Iridium - Platinum, which form the family of platinum metals (platinoids).

At the bottom of the table of D. I. Mendeleev are the chemical elements that form the lanthanide family and the actinide family. All these elements are formally included in the third group and come after the chemical elements lanthanum (number 57) and actinium (number 89).

The Periodic Table of the Elements contains ten rows. Small periods (first, second and third) consist of one row, large periods (fourth, fifth and sixth) contain two rows each. There is one row in the seventh period.

Each major period consists of even and odd rows. Paired rows contain metal elements, in odd rows, the properties of the elements change in the same way as in typical elements, i.e. from metallic to pronounced non-metallic.

Each group of the table of D. I. Mendeleev consists of two subgroups: the main and the secondary. The composition of the main subgroups includes elements of both small and large periods, that is, the main subgroups begin either from the first or second period. The secondary subgroups include elements of only large periods, i.e. side subgroups begin only from the fourth period.

The periodic table is one of the greatest discoveries of mankind, which made it possible to streamline knowledge about the world around us and discover new chemical elements. It is necessary for schoolchildren, as well as for everyone who is interested in chemistry. In addition, this scheme is indispensable in other areas of science.

This scheme contains all the elements known to man, 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, the Latin pronunciation in Russian of which 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, then 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. In the fifth group there are elements such as nitrogen, phosphorus, vanadium, arsenic, niobium, antimony are located below, then bismuth tantalum comes and completes the dubnium group. 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 borium. The last group is the most numerous. It includes gases such as helium, neon, argon, krypton, xenon and radon. This group also includes the metals iron, cobalt, nickel, rhodium, palladium, ruthenium, osmium, iridium, platinum. Next come hannium and meitnerium. Separately located elements that form the actinide series and the lanthanide series. They have similar properties to lanthanum and actinium.

This scheme includes all types of elements, which are divided into 2 large groups - metals and non-metals with different properties. How to determine the belonging of an element to a particular group, a conditional line will help, which must be drawn from boron to astatine. It should be remembered that such a line can only be drawn in the full version of the table. All elements that are above this line and are located in the main subgroups are considered non-metals. And which are lower, in the main subgroups - metals. Also, metals are substances that are in side subgroups. There are special pictures and photos on which you can get acquainted with the position of these elements in detail. 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 also 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 equally both basic and acid properties. The predominance of certain properties depends on the reaction conditions and the substances with which the amphoteric element reacts.

It should be noted that this scheme in the traditional execution of good quality is color. At the same time, different colors for ease of orientation are indicated main and secondary subgroups. And also elements are grouped depending on the similarity of their properties.
However, at present, along with the color scheme, the black-and-white periodic table of Mendeleev is very common. This form is used for black and white printing. Despite the apparent complexity, working with it is just as convenient, given some of the nuances. So, in this case, it is possible to 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 indicated different colors.
It is worth noting that in a single-color design it is not very difficult to navigate the scheme. For this, the information indicated in each individual cell of the element will be enough.

The exam today is the main type of test at the end of school, which means that special attention must be paid to preparing for it. Therefore, when choosing final exam in chemistry, you need to pay attention to the materials that can help in its delivery. As a rule, students 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 benefit in tests, 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 that you don't face any difficulties in the exam.

In addition to the main table characterizing the properties of elements and their dependence on atomic mass, there are other schemes that can help in the study of chemistry. For example, there are tables of solubility and electronegativity of substances. The first one can determine how soluble a particular compound is in water at ordinary 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 in the table. And at the place of their intersection there will be the necessary designation.

If it is the letter "r", then the substance is completely soluble in water under normal conditions. In the presence of the letter "m" - the substance is slightly soluble, and in the presence of the letter "n" - it almost does not dissolve. 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 the elements can vary from 1 to 8, there is also a special table to determine this parameter.

Another useful table is the metal activity series. All metals are located in it by increasing the degree of electrochemical potential. A series of stress metals begins with lithium, ends with gold. It is believed that the more to the left a metal occupies in this row, the more active it is in chemical reactions. Thus, the most active metal Lithium is considered to be an alkaline metal. Hydrogen is also present at the end of the list of elements. It is believed that the metals that are located after it are practically inactive. Among them are elements such as copper, mercury, silver, platinum and gold.

Periodic table pictures in good quality

This scheme is one of the greatest achievements in the field of chemistry. Wherein There are many types of this table.- a short version, a long one, as well as an extra long one. The most common is the short table, and the long version of the schema is also common. It is worth noting that the short version of the scheme is not currently recommended by IUPAC for use.
Total was more than a hundred types of tables have been developed, which differ in presentation, shape, and graphical representation. They are used in various fields of science, or not used at all. Currently, new circuit configurations continue to be developed by researchers. As the main option, either a short or a long circuit in excellent quality is used.