Periodic table sign. Periodic system of chemical elements of D.I. Mendeleev

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 Émile 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.

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.

A chemical element is a collective term that describes a set of atoms of a simple substance, that is, one that cannot be divided into any simpler (according to the structure of their molecules) components. Imagine that you receive a piece of pure iron with a request to split it into hypothetical components using any device or method ever invented by chemists. However, you can't do anything, the iron will never be divided into something simpler. A simple substance - iron - corresponds to the chemical element Fe.

Theoretical definition

The experimental fact noted above can be explained using the following definition: a chemical element is an abstract collection of atoms (not molecules!) of the corresponding simple substance, i.e. atoms of the same type. If there were a way to look at each of the individual atoms in the piece of pure iron mentioned above, then they would all be the same - iron atoms. In contrast, a chemical compound, such as iron oxide, always contains at least two different kinds of atoms: iron atoms and oxygen atoms.

Terms you should know

Atomic mass: the mass of protons, neutrons and electrons that make up an atom of a chemical element.

atomic number: the number of protons in the nucleus of an element's atom.

chemical symbol: a letter or pair of Latin letters representing the designation of the given element.

Chemical compound: a substance that consists of two or more chemical elements combined with each other in a certain proportion.

Metal: An element that loses electrons in chemical reactions with other elements.

Metalloid: An element that reacts sometimes as a metal and sometimes as a non-metal.

Non-metal: an element that seeks to obtain electrons in chemical reactions with other elements.

Periodic system of chemical elements: a system for classifying chemical elements according to their atomic numbers.

synthetic element: one that is obtained artificially in the laboratory, and usually does not occur in nature.

Natural and synthetic elements

Ninety-two chemical elements occur naturally on Earth. The rest were obtained artificially in laboratories. A synthetic chemical element is typically the product of nuclear reactions in particle accelerators (devices used to increase the speed of subatomic particles such as electrons and protons) or nuclear reactors (devices used to manipulate the energy released from nuclear reactions). The first synthesized element with atomic number 43 was technetium, discovered in 1937 by Italian physicists C. Perrier and E. Segre. Apart from technetium and promethium, all synthetic elements have nuclei larger than those of uranium. The last synthetic element to be named is livermorium (116), and before that was flerovium (114).

Two dozen common and important elements

Name	Symbol	Percentage of all atoms *				Properties of chemical elements (under normal room conditions)
		In the Universe	In the earth's crust	In sea water	In the human body
Aluminum	Al	-	6,3	-	-	Lightweight, silver metal
Calcium	Ca	-	2,1	-	0,02	Included in natural minerals, shells, bones
Carbon	FROM	-	-	-	10,7	Basis of all living organisms
Chlorine	Cl	-	-	0,3	-	poisonous gas
Copper	Cu	-	-	-	-	Only red metal
Gold	Au	-	-	-	-	Only yellow metal
Helium	He	7,1	-	-	-	Very light gas
Hydrogen	H	92,8	2,9	66,2	60,6	The lightest of all elements; gas
Iodine	I	-	-	-	-	Non-metal; used as an antiseptic
Iron	Fe	-	2,1	-	-	Magnetic metal; used for the production of iron and steel
Lead	Pb	-	-	-	-	Soft, heavy metal
Magnesium	mg	-	2,0	-	-	Very light metal
Mercury	hg	-	-	-	-	Liquid metal; one of two liquid elements
Nickel	Ni	-	-	-	-	Corrosion resistant metal; used in coins
Nitrogen	N	-	-	-	2,4	Gas, the main component of air
Oxygen	ABOUT	-	60,1	33,1	25,7	Gas, the second important air component
Phosphorus	R	-	-	-	0,1	Non-metal; important for plants
Potassium	TO	-	1.1	-	-	Metal; important for plants; commonly referred to as "potash"

* If the value is not specified, then the element is less than 0.1 percent.

Big bang as the root cause of the formation of matter

What chemical element was the very first in the universe? Scientists believe that the answer to this question lies in the stars and the processes by which stars are formed. The universe is believed to have originated at some point in time between 12 and 15 billion years ago. Until this moment, nothing that exists, except for energy, is conceived. But something happened that turned this energy into a huge explosion (the so-called Big Bang). In the seconds following the Big Bang, matter began to form.

The first simplest forms of matter to appear were protons and electrons. Some of them are combined into hydrogen atoms. The latter consists of one proton and one electron; it is the simplest atom that can exist.

Slowly, over long periods of time, hydrogen atoms began to gather together in certain regions of space, forming dense clouds. Hydrogen in these clouds was pulled into compact formations by gravitational forces. Eventually these clouds of hydrogen became dense enough to form stars.

Stars as chemical reactors of new elements

A star is simply a mass of matter that generates the energy of nuclear reactions. The most common of these reactions is the combination of four hydrogen atoms to form one helium atom. As soon as stars began to form, helium became the second element to appear in the universe.

As stars get older, they switch from hydrogen-helium nuclear reactions to other types. In them, helium atoms form carbon atoms. Later carbon atoms form oxygen, neon, sodium and magnesium. Still later, neon and oxygen combine with each other to form magnesium. As these reactions continue, more and more chemical elements are formed.

The first systems of chemical elements

Over 200 years ago, chemists began looking for ways to classify them. In the middle of the nineteenth century, about 50 chemical elements were known. One of the questions that chemists sought to resolve. boiled down to the following: is a chemical element a substance completely different from any other element? Or are some elements related to others in some way? Is there a common law that unites them?

Chemists have proposed various systems of chemical elements. So, for example, the English chemist William Prout in 1815 suggested that the atomic masses of all elements are multiples of the mass of the hydrogen atom, if we take it equal to one, that is, they must be integers. At that time, the atomic masses of many elements had already been calculated by J. Dalton in relation to the mass of hydrogen. However, if this is approximately the case for carbon, nitrogen, oxygen, then chlorine with a mass of 35.5 did not fit into this scheme.

The German chemist Johann Wolfgang Dobereiner (1780-1849) showed in 1829 that three elements from the so-called halogen group (chlorine, bromine and iodine) could be classified by their relative atomic masses. The atomic weight of bromine (79.9) turned out to be almost exactly the average of the atomic weights of chlorine (35.5) and iodine (127), namely 35.5 + 127 ÷ 2 = 81.25 (close to 79.9). This was the first approach to the construction of one of the groups of chemical elements. Doberiner discovered two more such triads of elements, but he failed to formulate a general periodic law.

How did the periodic table of chemical elements appear?

Most of the early classification schemes were not very successful. Then, around 1869, almost the same discovery was made by two chemists at almost the same time. The Russian chemist Dmitri Mendeleev (1834-1907) and the German chemist Julius Lothar Meyer (1830-1895) proposed organizing elements that have similar physical and chemical properties into an ordered system of groups, series, and periods. At the same time, Mendeleev and Meyer pointed out that the properties of chemical elements are periodically repeated depending on their atomic weights.

Today, Mendeleev is generally considered to be the discoverer of the periodic law because he took one step that Meyer did not. When all the elements were located in the periodic table, some gaps appeared in it. Mendeleev predicted that these were sites for elements that had not yet been discovered.

However, he went even further. Mendeleev predicted the properties of these not yet discovered elements. He knew where they were located on the periodic table, so he could predict their properties. It is noteworthy that every predicted chemical element Mendeleev, the future gallium, scandium and germanium, was discovered less than ten years after he published the periodic law.

Short form of the periodic table

There were attempts to calculate how many variants of the graphic representation of the periodic system were proposed by different scientists. It turned out to be more than 500. Moreover, 80% of the total number of options are tables, and the rest are geometric shapes, mathematical curves, etc. As a result, four types of tables have found practical application: short, semi-long, long and ladder (pyramidal). The latter was proposed by the great physicist N. Bohr.

The figure below shows the short form.

In it, the chemical elements are arranged in ascending order of their atomic numbers from left to right and from top to bottom. So, the first chemical element of the periodic table, hydrogen, has atomic number 1 because the nuclei of hydrogen atoms contain one and only one proton. Similarly, oxygen has an atomic number of 8, since the nuclei of all oxygen atoms contain 8 protons (see the figure below).

The main structural fragments of the periodic system are periods and groups of elements. In six periods, all cells are filled, the seventh is not yet completed (elements 113, 115, 117 and 118, although synthesized in laboratories, have not yet been officially registered and do not have names).

Groups are divided into main (A) and secondary (B) subgroups. The elements of the first three periods, containing one series-line each, are included exclusively in A-subgroups. The remaining four periods include two rows each.

Chemical elements in the same group tend to have similar chemical properties. So, the first group consists of alkali metals, the second - alkaline earth. Elements in the same period have properties that slowly change from an alkali metal to a noble gas. The figure below shows how one of the properties - atomic radius - changes for individual elements in the table.

Long period form of the periodic table

It is shown in the figure below and is divided in two directions, by rows and by columns. There are seven period rows, as in the short form, and 18 columns, called groups or families. In fact, the increase in the number of groups from 8 in short form to 18 in long form is obtained by placing all elements in periods starting from the 4th, not in two, but in one line.

Two different numbering systems are used for groups, as shown at the top of the table. The Roman numeral system (IA, IIA, IIB, IVB, etc.) has traditionally been popular in the US. Another system (1, 2, 3, 4, etc.) is traditionally used in Europe and was recommended for use in the USA a few years ago.

The appearance of the periodic tables in the figures above is a little misleading, as with any such published table. The reason for this is that the two groups of elements shown at the bottom of the tables should actually be located within them. The lanthanides, for example, belong to period 6 between barium (56) and hafnium (72). In addition, the actinides belong to period 7 between radium (88) and rutherfordium (104). If they were pasted into a table, it would be too wide to fit on a piece of paper or a wall chart. Therefore, it is customary to place these elements at the bottom of the table.

If the periodic table seems difficult for you to understand, you are not alone! Although it can be difficult to understand its principles, learning to work with it will help in the study of natural sciences. To get started, study the structure of the table and what information can be learned from it about each chemical element. Then you can start exploring the properties of each element. And finally, using the periodic table, you can determine the number of neutrons in an atom of a particular chemical element.

Steps

Part 1

Table structure

The periodic table, or periodic table of chemical elements, begins at the top left and ends at the end of the last line of the table (bottom right). The elements in the table are arranged from left to right in ascending order of their atomic number. The atomic number tells you how many protons are in one atom. In addition, as the atomic number increases, so does the atomic mass. Thus, by the location of an element in the periodic table, you can determine its atomic mass.

As you can see, each next element contains one more proton than the element preceding it. This is obvious when you look at the atomic numbers. Atomic numbers increase by one as you move from left to right. Since the elements are arranged in groups, some table cells remain empty.

• For example, the first row of the table contains hydrogen, which has atomic number 1, and helium, which has atomic number 2. However, they are on opposite ends because they belong to different groups.

1. Learn about groups that include elements with similar physical and chemical properties. The elements of each group are located in the corresponding vertical column. As a rule, they are indicated by the same color, which helps to identify elements with similar physical and chemical properties and predict their behavior. All elements of a particular group have the same number of electrons in the outer shell.

   • Hydrogen can be attributed both to the group of alkali metals and to the group of halogens. In some tables it is indicated in both groups.
   • In most cases, the groups are numbered from 1 to 18, and the numbers are placed at the top or bottom of the table. Numbers can be given in Roman (eg IA) or Arabic (eg 1A or 1) numerals.
   • When moving along the column from top to bottom, they say that you are "browsing the group".

2. Find out why there are empty cells in the table. Elements are ordered not only according to their atomic number, but also according to groups (elements of the same group have similar physical and chemical properties). This makes it easier to understand how an element behaves. However, as the atomic number increases, elements that fall into the corresponding group are not always found, so there are empty cells in the table.

   • For example, the first 3 rows have empty cells, since transition metals are found only from atomic number 21.
   • Elements with atomic numbers from 57 to 102 belong to the rare earth elements, and they are usually placed in a separate subgroup in the lower right corner of the table.

3. Each row of the table represents a period. All elements of the same period have the same number of atomic orbitals in which electrons are located in atoms. The number of orbitals corresponds to the period number. The table contains 7 rows, that is, 7 periods.

   • For example, the atoms of the elements of the first period have one orbital, and the atoms of the elements of the seventh period have 7 orbitals.
   • As a rule, periods are indicated by numbers from 1 to 7 on the left of the table.
   • As you move along a line from left to right, you are said to be "scanning through a period".

4. Learn to distinguish between metals, metalloids and non-metals. You will better understand the properties of an element if you can determine what type it belongs to. For convenience, in most tables, metals, metalloids and non-metals are indicated by different colors. Metals are on the left, and non-metals are on the right side of the table. Metalloids are located between them.

   Part 2

   Element designations

   1. Each element is designated by one or two Latin letters. As a rule, the element symbol is shown in large letters in the center of the corresponding cell. A symbol is an abbreviated name for an element that is the same in most languages. When doing experiments and working with chemical equations, the symbols of the elements are commonly used, so it is useful to remember them.

      • Typically, element symbols are shorthand for their Latin name, although for some, especially recently discovered elements, they are derived from the common name. For example, helium is denoted by the symbol He, which is close to the common name in most languages. At the same time, iron is designated as Fe, which is an abbreviation of its Latin name.

   2. Pay attention to the full name of the element, if it is given in the table. This "name" of the element is used in normal texts. For example, "helium" and "carbon" are the names of the elements. Usually, though not always, the full names of the elements are given under their chemical symbol.

      • Sometimes the names of the elements are not indicated in the table and only their chemical symbols are given.

   3. Find the atomic number. Usually the atomic number of an element is located at the top of the corresponding cell, in the middle or in the corner. It can also appear below the symbol or element name. Elements have atomic numbers from 1 to 118.

      • The atomic number is always an integer.

   4. Remember that the atomic number corresponds to the number of protons in an atom. All atoms of an element contain the same number of protons. Unlike electrons, the number of protons in the atoms of an element remains constant. Otherwise, another chemical element would have turned out!

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

FROM 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

All chemical elements can be characterized depending on the structure of their atoms, as well as by their position in the Periodic system of D.I. 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 a brief description of 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. The highest oxide - V 2 O 5 - exhibits amphoteric properties, with a predominance of acidic:

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

V 2 O 5 + H 2 SO 4 \u003d (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

The task

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

The task	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.