Elements of the 5th group of the periodic table. Periodic system of chemical elements of D.I. Mendeleev

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

A little background

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

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

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

Creating a Periodic Table

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

Legend of Mendeleev's dream

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

Further work

In the period from 1869 to 1871, Mendeleev developed the ideas of periodicity, to which the scientific community was inclined. And one of milestones 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 based on the results of research in the change of glass-forming oxides, the chemist managed to amend the values of the atomic masses of some elements, among which were uranium, indium, beryllium and others.

Of course, Mendeleev wanted to fill the empty cells that remained in the table as soon as possible, and in 1870 he predicted that chemical elements unknown to science would soon be discovered, atomic masses and whose properties 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, among them: polonium (1898), rhenium (1925), technetium (1937), francium (1939) and astatine (1942-1943). By the way, in 1900, D. I. Mendeleev and the Scottish chemist William Ramsay came to the conclusion that the elements of the zero group should also be included in the table - until 1962 they were called inert, and after - noble gases.

Organization of the periodic system

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

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

Creative Process Lessons

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

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

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

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

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

All chemical elements can be characterized depending on the structure of their atoms, as well as their position in Periodic system DI. Mendeleev. Usually, the characteristics of a chemical element are given according to the following plan:

indicate the symbol of the chemical element, as well as its name;
based on the position of the element in the Periodic system of D.I. Mendeleev indicate its ordinal, period number and group (type of subgroup) in which the element is located;
based on the structure of the atom, indicate the nuclear charge, mass number, the number of electrons, protons and neutrons in the atom;
write down the electronic configuration and indicate the valence electrons;
draw electron-graphic formulas for valence electrons in the ground and excited (if possible) states;
indicate the family of the element, as well as its type (metal or non-metal);
indicate the formulas of higher oxides and hydroxides with brief description their properties;
indicate the values of the minimum and maximum oxidation states of a chemical element.

Characteristics of a chemical element using the example of vanadium (V)

Consider the characteristics of a chemical element using the example of vanadium (V) according to the plan described above:

1. V - vanadium.

2. Ordinal number - 23. The element is in the 4th period, in the V group, A (main) subgroup.

3. Z=23 (nuclear charge), M=51 (mass number), e=23 (number of electrons), p=23 (number of protons), n=51-23=28 (number of neutrons).

4. 23 V 1s 2 2s 2 2p 6 3s 2 3p 6 3d 3 4s 2 – electronic configuration, valence electrons 3d 3 4s 2 .

5. Basic state

excited state

6. d-element, metal.

7. Higher oxide - V 2 O 5 - shows amphoteric properties, with a predominance of acid:

V 2 O 5 + 2NaOH \u003d 2NaVO 3 + H 2 O

V 2 O 5 + H 2 SO 4 = (VO 2) 2 SO 4 + H 2 O (pH<3)

Vanadium forms hydroxides of the following composition V(OH) 2 , V(OH) 3 , VO(OH) 2 . V(OH) 2 and V(OH) 3 are characterized by basic properties (1, 2), and VO(OH) 2 has amphoteric properties (3, 4):

V (OH) 2 + H 2 SO 4 \u003d VSO 4 + 2H 2 O (1)

2 V (OH) 3 + 3 H 2 SO 4 \u003d V 2 (SO 4) 3 + 6 H 2 O (2)

VO(OH) 2 + H 2 SO 4 = VOSO 4 + 2 H 2 O (3)

4 VO (OH) 2 + 2KOH \u003d K 2 + 5 H 2 O (4)

8. Minimum oxidation state "+2", maximum - "+5"

Examples of problem solving

EXAMPLE 1

Exercise

Describe the chemical element phosphorus

Solution

1. P - phosphorus.

2. Ordinal number - 15. The element is in the 3rd period, in the V group, A (main) subgroup.

3. Z=15 (nuclear charge), M=31 (mass number), e=15 (number of electrons), p=15 (number of protons), n=31-15=16 (number of neutrons).

4. 15 P 1s 2 2s 2 2p 6 3s 2 3p 3 – electronic configuration, valence electrons 3s 2 3p 3 .

5. Basic state

excited state

6. p-element, non-metal.

7. The highest oxide - P 2 O 5 - exhibits acidic properties:

P 2 O 5 + 3Na 2 O \u003d 2Na 3 PO 4

The hydroxide corresponding to the higher oxide - H 3 PO 4, exhibits acidic properties:

H 3 PO 4 + 3NaOH \u003d Na 3 PO 4 + 3H 2 O

8. The minimum oxidation state is "-3", the maximum is "+5"

EXAMPLE 2

Exercise	Describe the chemical element potassium
Solution	1. K - potassium. 2. Ordinal number - 19. The element is in period 4, in group I, A (main) subgroup.

Knowing the formulation of the periodic law and using the periodic system of elements of D. I. Mendeleev, one can characterize any chemical element and its compounds. It is convenient to add up such a characteristic of a chemical element according to a plan.

I. Symbol of a chemical element and its name.

II. The position of a chemical element in the periodic system of elements D.I. Mendeleev:

serial number;
period number;
group number;
subgroup (main or secondary).

III. The structure of the atom of a chemical element:

the charge of the nucleus of an atom;
relative atomic mass of a chemical element;
the number of protons;
the number of electrons;
the number of neutrons;
the 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 higher 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, let's provide a characteristic of a chemical element with serial number 15 and its compounds according to the position in the periodic system of elements of D. I. Mendeleev and the structure of the atom.

I. We find in the table of D. I. Mendeleev 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 the table of D. I. Mendeleev (number of the period, group, type of subgroup).

Phosphorus is in the main subgroup of group V, in the 3rd period.

III. Let us 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 with 15 electrons.

IV. We compose the electronic and electron-graphic formulas of the atom, mark its valence electrons.

The electronic formula of the phosphorus atom is: 15 P 1s 2 2s 2 2p 6 3s 2 3p 3 .

The electron-graphic formula of the external level of the phosphorus atom: on the third energy level, there are two electrons on the 3s sublevel (two arrows with the opposite direction are written in one cell), three electrons are on three p-sublevels (in each of the three cells, one arrows pointing in 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 last sublevel in the phosphorus atom, which is filled with electrons, is the p-sublevel, Phosphorus belongs to the family of p-elements.

VI. We draw up formulas for the higher oxide and hydroxide of phosphorus and characterize their properties (basic, acidic or amphoteric).

The highest phosphorus oxide P 2 O 5 exhibits the properties of an acid oxide. The hydroxide corresponding to the higher oxide, H 3 PO 4 , exhibits the properties of an acid. We confirm these properties with the equations of the types of chemical reactions:

P 2 O 5 + 3 Na 2 O \u003d 2Na 3 PO 4

H 3 PO 4 + 3NaOH \u003d 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.

The neighbor of phosphorus in the subgroup is nitrogen. The neighbors of phosphorus over the period are silicon and sulfur. Non-metallic properties of atoms of chemical elements of the main subgroups with increasing serial 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. 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 non-metals in most cases is equal to the difference between the group number and the number eight. So, the minimum oxidation state of phosphorus is -3.

See also: List of chemical elements by atomic number and Alphabetical list of chemical elements Contents 1 Symbols currently used ... Wikipedia

See also: List of chemical elements by atomic number and List of chemical elements by symbols 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 of the 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 graphical expression of the periodic law established by the Russian ... ... Wikipedia

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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 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 of electrons in atoms 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

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:

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

Thematic materials: