Seventh in the periodic table. Periodic system of chemical elements of D.I. 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

Mendeleev 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. 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 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.

In nature, there are a lot of repeating sequences:

• seasons;
• Times of Day;
• days of the week…

In the middle of the 19th century, D.I. Mendeleev noticed that the chemical properties of elements also have a certain sequence (they say that this idea came to him in a dream). The result of the miraculous dreams of the scientist was the Periodic Table of Chemical Elements, in which D.I. Mendeleev arranged the chemical elements in order of increasing atomic mass. In the modern table, the chemical elements are arranged in ascending order of the atomic number of the element (the number of protons in the nucleus of an atom).

The atomic number is shown above the symbol of a chemical element, below the symbol is its atomic mass (the sum of protons and neutrons). Note that the atomic mass of some elements is a non-integer! Remember isotopes! Atomic mass is the weighted average of all the isotopes of an element that occur naturally under natural conditions.

Below the table are the lanthanides and actinides.

Metals, non-metals, metalloids

They are located in the Periodic Table to the left of the stepped diagonal line that starts with Boron (B) and ends with polonium (Po) (the exceptions are germanium (Ge) and antimony (Sb). It is easy to see that metals occupy most of the Periodic Table. The main properties of metals : solid (except mercury); shiny; good electrical and thermal conductors; ductile; malleable; easily donate electrons.

The elements to the right of the stepped diagonal B-Po are called non-metals. The properties of non-metals are directly opposite to the properties of metals: poor conductors of heat and electricity; fragile; non-forged; non-plastic; usually accept electrons.

Metalloids

Between metals and non-metals are semimetals(metalloids). They are characterized by the properties of both metals and non-metals. Semimetals have found their main industrial application in the production of semiconductors, without which no modern microcircuit or microprocessor is inconceivable.

Periods and groups

As mentioned above, the periodic table consists of seven periods. In each period, the atomic numbers of the elements increase from left to right.

The properties of elements in periods change sequentially: so sodium (Na) and magnesium (Mg), which are at the beginning of the third period, give up electrons (Na gives up one electron: 1s 2 2s 2 2p 6 3s 1; Mg gives up two electrons: 1s 2 2s 2 2p 6 3s 2). But chlorine (Cl), located at the end of the period, takes one element: 1s 2 2s 2 2p 6 3s 2 3p 5.

In groups, on the contrary, all elements have the same properties. For example, in the IA(1) group, all elements from lithium (Li) to francium (Fr) donate one electron. And all elements of group VIIA(17) take one element.

Some groups are so important that they have been given special names. These groups are discussed below.

Group IA(1). The atoms of the elements of this group have only one electron in the outer electron layer, so they easily donate one electron.

The most important alkali metals are sodium (Na) and potassium (K), since they play an important role in the process of human life and are part of salts.

Electronic configurations:

• Li- 1s 2 2s 1 ;
• Na- 1s 2 2s 2 2p 6 3s 1 ;
• K- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1

Group IIA(2). The atoms of the elements of this group have two electrons in the outer electron layer, which also give up during chemical reactions. The most important element is calcium (Ca) - the basis of bones and teeth.

Electronic configurations:

• Be- 1s 2 2s 2 ;
• mg- 1s 2 2s 2 2p 6 3s 2 ;
• Ca- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2

Group VIIA(17). Atoms of the elements of this group usually receive one electron each, because. on the outer electronic layer there are five elements each, and one electron is just missing to the "complete set".

The most famous elements of this group are: chlorine (Cl) - is part of salt and bleach; iodine (I) is an element that plays an important role in the activity of the human thyroid gland.

Electronic configuration:

• F- 1s 2 2s 2 2p 5 ;
• Cl- 1s 2 2s 2 2p 6 3s 2 3p 5 ;
• Br- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5

Group VIII(18). Atoms of the elements of this group have a fully "staffed" outer electron layer. Therefore, they "do not need" to accept electrons. And they don't want to give them away. Hence - the elements of this group are very "reluctant" to enter into chemical reactions. For a long time it was believed that they do not react at all (hence the name "inert", i.e. "inactive"). But chemist Neil Barlett discovered that some of these gases, under certain conditions, can still react with other elements.

Electronic configurations:

• Ne- 1s 2 2s 2 2p 6 ;
• Ar- 1s 2 2s 2 2p 6 3s 2 3p 6 ;
• kr- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6

Valence elements in groups

It is easy to see that within each group, the elements are similar to each other in their valence electrons (electrons of s and p orbitals located on the outer energy level).

Alkali metals have 1 valence electron each:

• Li- 1s 2 2s 1 ;
• Na- 1s 2 2s 2 2p 6 3s 1 ;
• K- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1

Alkaline earth metals have 2 valence electrons:

• Be- 1s 2 2s 2 ;
• mg- 1s 2 2s 2 2p 6 3s 2 ;
• Ca- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2

Halogens have 7 valence electrons:

• F- 1s 2 2s 2 2p 5 ;
• Cl- 1s 2 2s 2 2p 6 3s 2 3p 5 ;
• Br- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5

Inert gases have 8 valence electrons:

• Ne- 1s 2 2s 2 2p 6 ;
• Ar- 1s 2 2s 2 2p 6 3s 2 3p 6 ;
• kr- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6

For more information, see the article Valency and the Table of electronic configurations of atoms of chemical elements by periods.

Let us now turn our attention to the elements located in groups with symbols V. They are located in the center of the periodic table and are called transition metals.

A distinctive feature of these elements is the presence of electrons in atoms that fill d-orbitals:

1. sc- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 1 ;
2. Ti- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2

Separate from the main table are located lanthanides and actinides are the so-called internal transition metals. In the atoms of these elements, electrons fill f-orbitals:

1. Ce- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 4d 10 5s 2 5p 6 4f 1 5d 1 6s 2 ;
2. Th- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 4d 10 5s 2 5p 6 4f 14 5d 10 6s 2 6p 6 6d 2 7s 2

PERIODIC TABLE OF MENDELEEV

The construction of Mendeleev's periodic table of chemical elements corresponds to the characteristic periods of number theory and orthogonal bases. Complementing 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 orders of magnitude 4 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 foundations 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 - sources of energy, and lead 207 (the end product, poisonous salts). Fluorine, of course, is 19. The orders of the Mersenne matrices correspond to a 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) corresponds to nitrogen 14 (atmospheric base). Table salt is formed by two "mersenne-like" atoms of sodium 23 and chlorine 35, together this combination is typical, just for Euler matrices. The more massive chlorine with a weight of 35.4 is a little short of the Hadamard dimension of 36. Common salt crystals: a cube (! ie, a meek character, Hadamars) and an octahedron (more defiant, this is undoubtedly Euler).

In atomic physics, the iron 56 - nickel 59 transition is the boundary between the elements that provide energy during the synthesis of a larger nucleus (hydrogen bomb) and decay (uranium bomb). The order 58 is famous for the fact that for it there are not only analogues of Hadamard matrices in the form of Belevich matrices with zeros on the diagonal, there are also no many weighted matrices for it - 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 orders 4 k+1, costs 257 fermii by the will of fate. You can't say anything, an exact hit. Here is gold 197. Copper 64 (63.547) and silver 108 (107.868), symbols of electronics, apparently do not 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 connected - 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 affects). Boron is a fairly complex element. Bohr plays a confusing role in the history of life itself. The framework structure in its structures is much more complicated than in diamond. The unique type of chemical bond that allows boron to absorb any impurity is very poorly understood, although a large number of scientists have already received Nobel Prizes for research related to it. The shape of the boron crystal is an icosahedron, five triangles form a vertex.

Platinum Mystery. The fifth element is, without a doubt, noble metals such as gold. Suspension over Hadamard dimension 4 k, for 1 large.

The stable isotope uranium 238

Recall, however, that Fermat numbers are rare (the closest is 257). Native gold crystals have a shape close to a cube, but the pentagram also sparkles. Its closest neighbor, platinum, a noble metal, is less than 4 times less atomic weight away from gold 197. Platinum has an atomic weight not 193, but somewhat increased, 194 (the order of the Euler matrices). A trifle, but it brings her into the camp of a few more aggressive elements. It is worth remembering, in connection with its inertness (it dissolves, perhaps, in aqua regia), platinum is used as an active catalyst for chemical processes.

Spongy platinum ignites hydrogen at room temperature. The nature of platinum is not at all peaceful, iridium 192 behaves more quietly (a mixture of isotopes 191 and 193). It is more like copper, but with the weight and character of gold.

Between neon 20 and sodium 23 there is no element with an atomic weight of 22. Of course, atomic weights are an integral characteristic. But among isotopes, in turn, there is also a curious correlation of properties with the properties of numbers and the corresponding matrices of orthogonal bases. As a nuclear fuel, the isotope uranium 235 (the order of the Mersenne matrices) has the greatest use, in which a self-sustaining nuclear chain reaction is possible. In nature, this element occurs in the stable form uranium 238 (the order of the Euler matrices). There is no element with an atomic weight of 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 seen in thirteenth-order matrices correlate.

Isotopes of chemical elements, island of stability

How to use the periodic table? For an uninitiated person, reading the periodic table is the same as looking at the ancient runes of elves for a dwarf. And the periodic table, by the way, if used correctly, can tell a lot about the world. In addition to serving you in the exam, it is also simply indispensable for solving a huge number of chemical and physical problems. But how to read it? Fortunately, today everyone can learn this art. In this article we will tell you how to understand the periodic table.

The periodic system of chemical elements (Mendeleev's table) is a classification of chemical elements that establishes the dependence of various properties of elements on the charge of the atomic nucleus.

History of the creation of the Table

Dmitri Ivanovich Mendeleev was not a simple chemist, if someone thinks so. He was a chemist, physicist, geologist, metrologist, ecologist, economist, oilman, aeronaut, instrument maker and teacher. During his life, the scientist managed to conduct a lot of fundamental research in various fields of knowledge. For example, it is widely believed that it was Mendeleev who calculated the ideal strength of vodka - 40 degrees. We do not know how Mendeleev treated vodka, but it is known for sure that his dissertation on the topic “Discourse on the combination of alcohol with water” had nothing to do with vodka and considered alcohol concentrations from 70 degrees. With all the merits of the scientist, the discovery of the periodic law of chemical elements - one of the fundamental laws of nature, brought him the widest fame.

There is a legend according to which the scientist dreamed of the periodic system, after which he only had to finalize the idea that had appeared. But, if everything were so simple .. This version of the creation of the periodic table, apparently, is nothing more than a legend. When asked how the table was opened, Dmitry Ivanovich himself answered: “ I’ve been thinking about it for maybe twenty years, and you think: I sat and suddenly ... it’s ready. ”

In the middle of the nineteenth century, attempts to streamline the known chemical elements (63 elements were known) were simultaneously undertaken by several scientists. For example, in 1862 Alexandre Emile Chancourtois placed the elements along a helix and noted the cyclical repetition of chemical properties. Chemist and musician John Alexander Newlands proposed his version of the periodic table in 1866. An interesting fact is that in the arrangement of the elements the scientist tried to discover some mystical musical harmony. Among other attempts was the attempt of Mendeleev, which was crowned with success.

In 1869, the first scheme of the table was published, and the day of March 1, 1869 is considered the day of the discovery of the periodic law. The essence of Mendeleev's discovery was that the properties of elements with increasing atomic mass do not change monotonously, but periodically. The first version of the table contained only 63 elements, but Mendeleev made a number of very non-standard decisions. So, he guessed to leave a place in the table for yet undiscovered elements, and also changed the atomic masses of some elements. The fundamental correctness of the law derived by Mendeleev was confirmed very soon, after the discovery of gallium, scandium and germanium, the existence of which was predicted by scientists.

Modern view of the periodic table

Below is the table itself.

Today, instead of atomic weight (atomic mass), the concept of atomic number (the number of protons in the nucleus) is used to order elements. The table contains 120 elements, which are arranged from left to right in ascending order of atomic number (number of protons)

The columns of the table are so-called groups, and the rows are periods. There are 18 groups and 8 periods in the table.

• The metallic properties of elements decrease when moving along the period from left to right, and increase in the opposite direction.
• The dimensions of atoms decrease as they move from left to right along the periods.
• When moving from top to bottom in the group, the reducing metallic properties increase.
• Oxidizing and non-metallic properties increase along the period from left to right. I am.

What do we learn about the element from the table? For example, let's take the third element in the table - lithium, and consider it in detail.

First of all, we see the symbol of the element itself and its name under it. In the upper left corner is the atomic number of the element, in the order in which the element is located in the table. The atomic number, as already mentioned, is equal to the number of protons in the nucleus. The number of positive protons is usually equal to the number of negative electrons in an atom (with the exception of isotopes).

The atomic mass is indicated under the atomic number (in this version of the table). If we round the atomic mass to the nearest integer, we get the so-called mass number. The difference between the mass number and the atomic number gives the number of neutrons in the nucleus. Thus, the number of neutrons in a helium nucleus is two, and in lithium - four.

So our course "Mendeleev's Table for Dummies" has ended. In conclusion, we invite you to watch a thematic video, and we hope that the question of how to use the periodic table of Mendeleev has become clearer to you. We remind you that learning a new subject is always more effective not alone, but with the help of an experienced mentor. That is why, you should never forget about those who will gladly share their knowledge and experience with you.

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 whether an element belongs 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 takes its place in this row, the more active it is in chemical reactions. In this way, 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.