16th element of the periodic table. Periodic table of chemical elements by D.I. Mendeleev

See also: List of chemical elements by atomic number and Alphabetical list of chemical elements Contents 1 Symbols used in at the moment... Wikipedia

See also: List of chemical elements by atomic number and List of chemical elements by symbol Alphabetical list of chemical elements. Nitrogen N Actinium Ac Aluminum Al Americium Am Argon Ar Astatine At ... Wikipedia

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. The system is a graphical expression periodic law,... ...Wikipedia

Chemical elements (periodic table) classification of chemical elements, establishing the dependence of various properties of elements on the charge of the atomic nucleus. The system is a graphic expression of the periodic law established by Russian... ... Wikipedia

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Japanese-English-Russian dictionary for installation of industrial equipment. About 8,000 terms, Popova I.S.. The dictionary is intended for a wide range of users and primarily for translators and technical specialists involved in the supply and implementation of industrial equipment from Japan or...

There are many repeating sequences in nature:

seasons;
Times of Day;
days of the week...

In the mid-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 scientist’s wonderful dreams was the Periodic Table of Chemical Elements, in which D.I. Mendeleev arranged chemical elements in order of increasing atomic mass. In the modern table, chemical elements are arranged in ascending order of the element's atomic number (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(sum of protons and neutrons). Please note that the atomic mass of some elements is not a whole number! Remember isotopes! Atomic mass is the weighted average of all isotopes of an element found in nature under natural conditions.

Below the table are lanthanides and actinides.

Metals, non-metals, metalloids

Located in the Periodic Table to the left of a stepped diagonal line that begins 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. Basic properties of metals : solid (except mercury); good electrical and thermal conductors; malleable; easily releases electrons.

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

Metalloids

Between metals and non-metals there are semimetals(metalloids). They are characterized by the properties of both metals and non-metals. Semimetals have found their main application in industry in the production of semiconductors, without which not a single modern microcircuit or microprocessor is conceivable.

Periods and groups

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

The properties of elements change sequentially in periods: thus sodium (Na) and magnesium (Mg), located 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 group IA(1), 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 received special names. These groups are discussed below.

Group IA(1). Atoms of elements of this group have only one electron in their outer electron layer, so they easily give up one electron.

The most important alkali metals are sodium (Na) and potassium (K), since they play an important role in 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). Atoms of elements of this group have two electrons in their outer electron layer, which they 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 elements of this group usually receive one electron each, because There are five elements on the outer electronic layer and one electron is just missing from the “complete set”.

The most well-known elements of this group: 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 elements of this group have a fully “complete” outer electron layer. Therefore, they “don’t” need to accept electrons. And they “don’t want” to give them away. Hence, elements of this group are very “reluctant” to join chemical reactions. For a long time it was believed that they did not react at all (hence the name “inert”, i.e. “inactive”). But chemist Neil Bartlett discovered that some of these gases can still react with other elements under certain conditions.

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 notice 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).

U alkali metals- 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 Valence and the Table of Electronic Configurations of Atoms of Chemical Elements by Period.

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

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

Sc- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 1 ;
Ti- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2

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

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 ;
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

He relied on the works of Robert Boyle and Antoine Lavuzier. The first scientist advocated the search for indecomposable chemical elements. Boyle listed 15 of these back in 1668.

Lavouzier 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 was 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 descendants. 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 elements.” The work was published in the 1870s. At the same time, the Russian scientist spoke before the country's chemical society and sent out 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, I worked with potassium and chlorine. Then, I took up the group of metals of the alkali group.

The chemist acquired a special table and cards of elements to play them like solitaire, looking for the necessary matches and combinations. As a result, an insight came: - the properties of components depend on the mass of their atoms. So, elements of the periodic table lined up.

The chemistry maestro's discovery was the decision to leave empty spaces in these rows. The periodicity of the difference between atomic masses forced the scientist to assume that not all elements are known to humanity. The weight gaps between some of the “neighbors” were too large.

That's why, periodic table became like a chess field, with an abundance of “white” cells. Time has shown that they were indeed waiting for their “guests”. For example, they became inert gases. Helium, neon, argon, krypton, radioactivity and xenon were discovered only in the 30s of the 20th century.

Now about the myths. It is widely believed that chemical table Mendeleev appeared to him in a dream. These are the machinations of university teachers, or rather, 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. One day, exhausted from the search, Dmitry fell asleep right in front of Alexander. He waited until the chemist woke up and saw Mendeleev grab a piece of paper and write 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 story, which grateful listeners quickly spread to the masses.

Features of the periodic table

Since the first version in 1969 periodic table has been improved more than once. Thus, with the discovery of noble gases in the 1930s, it was possible to derive a new dependence of elements - on their atomic numbers, and not on 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 figure is the serial number of the element.

20th century scientists studied and electronic structure atoms. It also affects the periodicity of elements and is reflected in later editions Periodic tables. Photo the list demonstrates that the substances in it are arranged in order of growth atomic weight.

They did not change the fundamental principle. The 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. The period is a horizontal row. Its beginning is typical metals, its end is elements with non-metallic properties. The decrease is gradual.

There are large and small periods. The first ones are at the beginning of the table, there are 3 of them. A period of 2 elements opens the list. Next come two columns, each containing 8 items. The remaining 4 periods are large. The 6th is the longest, with 32 elements. In the 4th and 5th there are 18 of them, and in the 7th - 24.

You can count how many elements are in the table Mendeleev. There are 112 titles in total. Namely names. There are 118 cells, and 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 dedicated to them. A gradual decrease from metals to inert substances is observed in the upper rows.

Pictures of the periodic table divided and vertical. This groups in the periodic table, there are 8 of them. Elements with similar 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– this is 112 positions. The essence of their arrangement into a single list is the systematization of the primary elements. People began to struggle with this back in ancient times.

Aristotle was one of the first to understand what all things are made of. He took as a basis the properties of substances - cold and heat. Empidocles identified 4 fundamental elements according to the elements: water, earth, fire and air.

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

It turns out that pronunciation of the periodic table– voicing a certain model of our reality, breaking it down into its components. However, learning them is not so 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 modern method. Computer scientists have developed a number of flash games to help memorize Periodic List. Project participants are offered to find elements using 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. It is also up to us to exclude element names and other parameters. This makes the search difficult. For the advanced, there is also a timer, that is, the training is carried out at speed.

Game conditions do study numbers of elements in the Mendleyev table not boring, but entertaining. Excitement awakens, and it becomes easier to systematize knowledge in your head. Those who do not accept computer flash projects offer more traditional way memorizing the list.

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

Thus, iron in the brain can be correlated, for example, with a nail, and mercury with a thermometer. Is the element name unfamiliar? We use the method of suggestive associations. , for example, let’s make up the words “toffee” and “speaker” from the beginnings.

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

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

Teachers also take this into account. As a rule, they do not force you to memorize the list; they allow you to look at it even during tests. Constantly looking at the table is equivalent to the effect of a printout on the wall, or writing cheat sheets before exams.

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

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

How to use the periodic table? For an uninitiated person, reading the periodic table is the same as for a gnome looking at the ancient runes of the elves. And the periodic table, by the way, if used correctly, can tell a lot about the world. In addition to serving you well in the exam, it is also simply irreplaceable in 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 table 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

Dmitry Ivanovich Mendeleev was not a simple chemist, if anyone thinks so. He was a chemist, physicist, geologist, metrologist, ecologist, economist, oil worker, 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 don’t know how Mendeleev felt about vodka, but we know 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 a scientist dreamed of the periodic table, after which all he had to do was refine the idea that had appeared. But if it were all that simple... This version The creation of the periodic table is, apparently, 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’re thinking: I was sitting there and suddenly... it’s done.”

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

In 1869, the first table diagram was published, and March 1, 1869 is considered the day the periodic law was opened. The essence of Mendeleev's discovery was that the properties of elements with increasing atomic mass do not change monotonically, but periodically. The first version of the table contained only 63 elements, but Mendeleev made a number of very unconventional decisions. So, he guessed to leave space in the table for still 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 the scientist.

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 order of increasing atomic number (number of protons)

The table columns represent so-called groups, and the rows represent periods. The table has 18 groups and 8 periods.

The metallic properties of elements decrease when moving along a period from left to right, and increase in the opposite direction.
The sizes of atoms decrease when moving from left to right along periods.
As you move from top to bottom through the group, the reducing metal properties increase.
Oxidizing and non-metallic properties increase when moving along a period from left to right I.

What do we learn about an 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 element symbol itself and its name below it. In the upper left corner is the atomic number of the element, in which order the element is arranged in the table. The atomic number, as already mentioned, equal to the number 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 what is called the 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 it is four.

Our course “Periodical Table for Dummies” has ended. In conclusion, we invite you to watch the thematic video, and we hope that the question of how to use the periodic table of Mendeleev has become more clear to you. We remind you what to study new item It is always more effective not alone, but with the help of an experienced mentor. That is why you should never forget about them, who will gladly share their knowledge and experience with you.

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 a chemical element in the periodic table of 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 in the main subgroup of group V, in the 3rd period.

III. We will provide general characteristics 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.

Electronic graphic formula for the outer level of a phosphorus atom: at the third energy level, at the 3s sublevel, there are two electrons (two arrows with opposite direction), there are three electrons on three p-sublevels (in each of the three cells one arrow is written, having the same direction).

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 the properties of an acidic oxide. The hydroxide corresponding to the 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.