Instruction

Take the periodic table, and use a ruler to draw a line that starts in a cell with the element Be (beryllium) and ends in a cell with the element At (Astatine).

Those elements that will be located to the left of this line are metals. Moreover, the “lower and to the left” the element is, the more pronounced metallic properties he has. It is easy to see that in the periodic table such a metal is (Fr) - the most active alkali metal.

Accordingly, those elements that are to the right of the line have properties. And here, too, a similar rule applies: the “higher and to the right” of the line is the element, the more strong non-metal he is. Such an element in the periodic table is fluorine (F), the strongest oxidizing agent. He is so active that chemists used to give him a respectful, albeit informal, "chewing everything."

Questions like “But what about those elements that are on the line itself or very close to it?” may arise. Or, for example, “To the right and above” of the line are chrome,. Are they non-metals? After all, they are used in the production of steel as alloying additives. But it is known that even small impurities of non-metals make brittle. The fact is that the elements located on the line itself (for example, aluminum, germanium, niobium, antimony) have, that is, a dual character.

As for, for example, vanadium, chromium, manganese, the properties of their compounds depend on the degree of oxidation of the atoms of these elements. For example, their higher oxides, such as V2O5, CrO3, Mn2O7, have pronounced . That is why they are located in seemingly "illogical" places in the periodic table. In their "pure" form, these elements are, of course, metals and have all the properties of metals.

Sources:

• metals in the periodic table

For schoolchildren study table Mendeleev - nightmare. Even thirty-six elements that teachers usually ask turn into hours of exhausting cramming and a headache. Many do not even believe what to learn table Mendeleev is real. But the use of mnemonics can greatly facilitate the life of schoolchildren.

Instruction

Understand the theory and choose the right technique Rules that make it easier to memorize the material, mnemonic. Their main trick is to create associations when abstract information is packaged into a bright picture, sound, or even smell. There are several mnemonic techniques. For example, you can write a story from the elements of memorized information, look for consonant words (rubidium - knife switch, cesium - Julius Caesar), include spatial imagination or just rhyme elements periodic table Mendeleev.

Ballad about nitrogen It is better to rhyme the elements of Mendeleev's periodic table with meaning, according to certain signs: according to valence, for example. So, alkaline ones rhyme very easily and sound like a song: "Lithium, potassium, sodium, rubidium, francium cesium." "Magnesium, calcium, zinc and barium - their valence is equal to a pair" - an unfading classic of school folklore. On the same topic: "Sodium, potassium, silver are monovalent good" and "Sodium, potassium and argentum are monovalent." Creativity, unlike cramming, which is enough for a maximum of a couple of days, stimulates long-term memory. So, more about aluminum, poems about nitrogen and songs about valency - and memorization will go like clockwork.

An acid thriller is invented to facilitate memorization, in which the elements of the periodic table turn into heroes, landscape details or plot elements. Here, for example, is a well-known text: “Asian (Nitrogen) began to pour (Lithium) water (Hydrogen) into Pinery(Bohr). But we didn’t need him (Neon), but Magnolia (Magnesium).” It can be supplemented with a story about a Ferrari (iron - ferrum), in which secret agent"Chlorine zero seventeen" (17 is the serial number of chlorine) to catch the maniac Arseny (arsenic - arsenicum), who had 33 teeth (33 - the serial number of arsenic), but something sour got into his mouth (oxygen), this there were eight poisoned bullets (8 is the serial number of oxygen) ... You can continue indefinitely. By the way, a novel written based on the periodic table can be attached to a literature teacher as an experimental text. She will surely like it.

Build a memory palace This is one of the pretty names efficient technique memorization when turned on spatial thinking. Its secret is that we can all easily describe our room or the way from home to the store, school,. In order to create a sequence of elements, you need to place them along the road (or in the room), and present each element very clearly, visibly, tangibly. Here is a skinny blond with a long face. The hard worker who lays the tiles is silicon. A group of aristocrats in an expensive car - inert gases. And, of course, balloons - helium.

note

No need to force yourself to remember the information on the cards. It is best to associate each element with some vividly. Silicon - with Silicon Valley. Lithium - with lithium batteries in mobile phone. There may be many options. But the combination visual image, mechanical memory, tactile sensation from a rough or, conversely, smooth glossy card, will help you easily pick up the smallest details from the depths of memory.

Useful advice

You can draw the same cards with information about the elements, as Mendeleev used to have, but only supplement them up-to-date information: the number of electrons in the outer level, for example. All you need to do is lay them out before bed.

Sources:

• Mnemonic rules for chemistry
• how to memorize the periodic table

The problem of definition is far from being idle. It will hardly be pleasant if in a jewelry store instead of an expensive gold thing they want to slip you an outright fake. Isn't it interesting from what metal made by a failed car part or a found antique?

Instruction

Here, for example, is how the presence of copper in an alloy is determined. Apply to cleaned surface metal drop (1:1) nitric acid. As a result of the reaction, gas will be released. After a few seconds, blot the drop with filter paper, then hold it over where it is concentrated solution ammonia. The copper will react, turning the stain dark blue.

Here's how to tell bronze from brass. Place a piece of metal shavings or sawdust in a beaker with 10 ml of a solution (1:1) of nitric acid and cover it with glass. Wait for a while to completely dissolve, and then heat the resulting liquid almost to a boil for 10-12 minutes. A white precipitate will remind you of bronze, and a beaker with brass will remain.

You can define nickel in much the same way as copper. Apply a drop of nitric acid solution (1:1) to the surface metal and wait 10-15 seconds. Blot the drop with filter paper and then hold it over concentrated ammonia vapor. On the resulting dark spot, drop a 1% solution of dimethylglyoxin in alcohol.

Nickel will "signal" you with a characteristic red color. Lead can be determined using chromic acid crystals and a drop of chilled water applied to it. acetic acid and a minute later - drops of water. If you see a yellow precipitate, know that it is lead chromate.

Pour a little of the investigated liquid into a separate container and drip a little bit of the lapis solution. In this case, a "curdled" white precipitate of insoluble silver chloride will instantly fall out. That is, there is definitely a chloride ion in the composition of a substance molecule. But maybe it's still not, but a solution of some kind of chlorine-containing salt? Like sodium chloride?

Remember another property of acids. Strong acids (and, of course, hydrochloric acid is one of them) can displace weak acids from them. Place a little soda powder - Na2CO3 into a flask or beaker and slowly add the test liquid. If a hiss is immediately heard and the powder literally “boils” - there will be no doubt left - this is hydrochloric acid.

Each element in the table is assigned a specific serial number (H - 1, Li - 2, Be - 3, etc.). This number corresponds to the nucleus (the number of protons in the nucleus) and the number of electrons revolving around the nucleus. The number of protons is thus equal to the number of electrons, which means that in normal conditions atom electrically.

The division into seven periods occurs according to the number of energy levels of the atom. Atoms of the first period have a single-level electron shell, the second - a two-level, the third - a three-level, etc. When a new energy level is filled, new period.

The first elements of any period are characterized by atoms that have one electron at the outer level - these are alkali metal atoms. The periods end with atoms of noble gases, which have an external energy level completely filled with electrons: in the first period, inert gases have 2 electrons, in the subsequent ones - 8. It is precisely because of the similar structure of the electron shells that groups of elements have similar physico-.

In the table D.I. Mendeleev there are 8 main subgroups. This number is due to the maximum possible number of electrons per energy level.

At the bottom of the periodic table, lanthanides and actinides are singled out as independent series.

Using the table D.I. Mendeleev, one can observe the periodicity of the following properties of elements: the radius of an atom, the volume of an atom; ionization potential; electron affinity forces; the electronegativity of the atom; ; physical properties of potential compounds.

A clearly traced periodicity in the arrangement of elements in the table D.I. Mendeleev is rationally explained by the consistent nature of the filling of energy levels by electrons.

Sources:

• periodic table

Periodic law, which is the basis modern chemistry and explaining the patterns of changes in properties chemical elements, was discovered by D.I. Mendeleev in 1869. physical meaning this law is revealed in the study complex structure atom.

In the 19th century, atomic mass was thought to be main characteristic element, so it was used to classify substances. Now atoms are defined and identified by the magnitude of the charge of their nucleus (number and serial number in the periodic table). However, the atomic mass of the elements, with some exceptions (for example, the atomic mass is less than atomic mass argon) increases in proportion to their nuclear charge.

With an increase in the atomic mass, a periodic change in the properties of elements and their compounds is observed. These are the metallicity and non-metallicity of atoms, atomic radius, ionization potential, electron affinity, electronegativity, oxidation states, compounds (boiling, melting points, density), their basicity, amphotericity or acidity.

How many elements are in the modern periodic table

Periodic table graphically expresses the law discovered by him. In modern periodic system contains 112 chemical elements (the latter are Meitnerium, Darmstadtium, Roentgenium and Copernicium). According to the latest data, the following 8 elements (up to 120 inclusive) have also been discovered, but not all of them have received their names, and these elements are still few in any printed publications.

Each element occupies a certain cell in the periodic system and has its own serial number corresponding to the charge of the nucleus of its atom.

How the periodic system is built

The structure of the periodic system is represented by seven periods, ten rows and eight groups. Each period begins with an alkali metal and ends with a noble gas. The exceptions are the first period, which begins with hydrogen, and the seventh incomplete period.

Periods are divided into small and large. Small periods (first, second, third) consist of one horizontal row, large ones (fourth, fifth, sixth) consist of two horizontal rows. The upper rows in large periods are called even, the lower rows are called odd.

In the sixth period of the table after (serial number 57) there are 14 elements similar in properties to lanthanum - lanthanides. They are taken out in lower part tables on a separate line. The same applies to actinides located after actinium (with number 89) and largely repeating its properties.

Even rows long periods(4, 6, 8, 10) are filled with metals only.

Elements in groups exhibit the same highest in oxides and other compounds, and this valence corresponds to the group number. The main ones contain elements of small and large periods, only large ones. From top to bottom, they increase, non-metallic ones weaken. All atoms of the side subgroups are metals.

The table of periodic chemical elements has become one of the major events in the history of science and brought to its creator, the Russian scientist Dmitri Mendeleev, world fame. This extraordinary person managed to combine all the chemical elements into a single concept, but how did he manage to open his famous table?

The periodic table is one of the main postulates of chemistry. With its help, you can find all the necessary elements, both alkaline and ordinary metals or non-metals. In this article, we will look at how to find the elements you need in such a table.

In the middle of the 19th century, 63 chemical elements were discovered. Initially, it was supposed to arrange the elements according to the increase in atomic mass and divide them into groups. However, it was not possible to structure them, and the proposal of the chemist Nuland was not taken seriously due to attempts to link chemistry and music.

In 1869 Dmitry Ivanovich Mendeleev published his periodic table for the first time on the pages of the Russian journal chemical society. He soon announced his discovery to chemists around the world. Mendeleev subsequently continued to refine and improve his table, until she acquired modern look. It was Mendeleev who managed to arrange the chemical elements in such a way that they changed not monotonously, but periodically. The theory was finally merged into the periodic law in 1871. Let's move on to the consideration of non-metals and metals in the periodic table.

How are metals and non-metals found?

Determination of metals by theoretical method

Theoretical method:

1. All metals, with the exception of mercury, are in a solid state of aggregation. They are plastic and bend easily. Also, these elements are distinguished by good heat and electrical conductive properties.
2. If you need to define a list of metals, then draw a diagonal line from boron to astatine, below which the metal components will be located. They also include all elements of side chemical groups.
3. In the first group, the first subgroup contains alkaline, for example, lithium or cesium. When dissolved, it forms alkalis, namely hydroxides. They have an electronic configuration of the ns1 type with one valence electron, which, when recoiling, leads to the manifestation of reducing properties.

In the second group main subgroup are alkaline earth metals like radium or calcium. At ordinary temperature they are solid state of aggregation. Their electronic configuration is ns2. The transition metals are located in side subgroups. They possess varying degrees oxidation. AT lower degrees main properties appear, intermediate degrees reveal acid properties, and amphoteric in higher degrees.

Theoretical definition of non-metals

First of all, such elements are usually found in liquid or gaseous state, sometimes in solid . When trying to bend them they break due to brittleness. Non-metals are poor conductors of heat and electricity. Non-metals are at the top diagonal line drawn from boron to astatine. The atoms of non-metals contain a large number of electrons, which is why it is more profitable for them to accept additional electrons than to give them away. Non-metals also include hydrogen and helium. All non-metals are located in groups from the second to the sixth.

Chemical methods of determination

There are several ways:

• Often have to apply chemical methods definitions of metals. For example, you need to determine the amount of copper in an alloy. To do this, apply a drop of nitric acid to the surface and after a while time will go steam. Blot the filter paper and hold it over a flask of ammonia. If the spot turns dark blue, then this indicates the presence of copper in the alloy.
• Suppose you need to find gold, but you don't want to confuse it with brass. Apply a 1 to 1 concentrated solution of nitric acid to the surface. a large number gold in the alloy there will be no reaction to the solution.
• Iron is considered a very popular metal. To determine it, you need to heat a piece of metal in hydrochloric acid. If it is really iron, then the flask will turn into yellow. If chemistry is enough for you problematic topic then take a magnet. If it is really iron, then it will be attracted to a magnet. Nickel is determined by almost the same method as copper, only additionally drop dimethylglyoxin on alcohol. Nickel will confirm itself with a red signal.

Other methods are determined in a similar way. metal elements. Just use the necessary solutions and everything will work out.

Conclusion

Periodic table of Mendeleev - an important postulate of chemistry. It allows you to find all the necessary elements, especially metals and non-metals. If you study some of the features of chemical elements, you can identify a number of features that help you find the desired element. You can also use by chemical means definitions of metals and non-metals, as they allow in practice to study this complex science. Good luck with your study of chemistry and Mendeleev's periodic table, it will help you with further scientific research!

Video

From the video you will learn how to determine metals and non-metals according to the periodic table.

Even at school, sitting in chemistry lessons, we all remember the table on the classroom wall or chemical laboratory. This table contains the classification of all known to mankind chemical elements, those fundamental components that make up the Earth and the entire Universe. Then we could not even think that periodic table undoubtedly one of the greatest scientific discoveries which is the foundation of our modern knowledge about chemistry.

Periodic system of chemical elements of D. I. Mendeleev

At first glance, her idea looks deceptively simple: organize chemical elements in ascending order of the weight of their atoms. Moreover, in most cases it turns out that the chemical and physical properties of each element are similar to the element preceding it in the table. This pattern is manifested for all elements, except for the very first few, simply because they do not have elements in front of them that are similar to them in atomic weight. It is thanks to the discovery of such a property that we can place a linear sequence of elements in a table very reminiscent of a wall calendar, and thus combine great amount types of chemical elements in a clear and coherent manner. Of course, today we use the concept atomic number(the number of protons) in order to order the system of elements. This helped solve the so-called technical problem"Pairs of permutations", however, did not lead to a fundamental change in the appearance of the periodic table.

AT Mendeleev's periodic table all elements are ordered according to their atomic number, electronic configuration and recurring chemical properties. The rows in a table are called periods, and the columns are called groups. The first table, dated 1869, contained only 60 elements, but now the table had to be enlarged to accommodate the 118 elements known to us today.

Periodic system of Mendeleev systematizes not only the elements, but also their most diverse properties. It is often enough for a chemist to have the Periodic Table in front of his eyes in order to correctly answer many questions (not only exams, but also scientific ones).

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Periodic Law

There are two formulations periodic law chemical elements: classical and modern.

Classical, as presented by its discoverer D.I. Mendeleev: properties simple bodies, as well as the forms and properties of the compounds of elements are in a periodic dependence on the values atomic weights elements .

Modern: properties simple substances, as well as the properties and forms of compounds of elements are in a periodic dependence on the charge of the nucleus of atoms of elements ( serial number) .

The graphic representation of the periodic law is the periodic system of elements, which is natural classification chemical elements, based on regular changes in the properties of elements from the charges of their atoms. The most common images of the periodic table of elements D.I. Mendeleev are short and long forms.

Groups and periods of the Periodic system

groups called the vertical rows in the periodic table. In groups, elements are combined according to the highest oxidation state in oxides. Each group consists of the main and secondary subgroups. The main subgroups include elements of small periods and elements of large periods identical with it in properties. Side subgroups consist only of elements of large periods. The chemical properties of the elements of the main and secondary subgroups differ significantly.

Period called horizontal row elements arranged in ascending order of ordinal (atomic) numbers. There are seven periods in the periodic system: the first, second and third periods are called small, they contain 2, 8 and 8 elements, respectively; the remaining periods are called large: in the fourth and fifth periods there are 18 elements each, in the sixth - 32, and in the seventh (still incomplete) - 31 elements. Each period, except the first, begins with an alkali metal and ends with a noble gas.

The physical meaning of the serial number chemical element: the number of protons in the atomic nucleus and the number of electrons revolving around atomic nucleus, are equal to the ordinal number of the element.

Properties of the periodic table

Recall that groups call the vertical rows in the periodic system and the chemical properties of the elements of the main and secondary subgroups differ significantly.

The properties of elements in subgroups naturally change from top to bottom:

• metallic properties are enhanced and non-metallic properties are weakened;
• the atomic radius increases;
• strength increases formed by the element bases and anoxic acids;
• electronegativity drops.

All elements except helium, neon and argon form oxygen compounds, there are only eight forms oxygen compounds. They are often depicted in the periodic table. general formulas, located under each group in ascending order of the oxidation state of the elements: R 2 O, RO, R 2 O 3, RO 2, R 2 O 5, RO 3, R 2 O 7, RO 4, where the symbol R denotes an element of this group. Formulas higher oxides apply to all elements of the group except exceptional cases when the elements do not exhibit an oxidation state equal to the group number (for example, fluorine).

Oxides of composition R 2 O exhibit strong basic properties, and their basicity increases with increasing serial number, oxides of composition RO (with the exception of BeO) exhibit basic properties. Oxides of the composition RO 2 , R 2 O 5 , RO 3 , R 2 O 7 exhibit acidic properties, and their acidity increases with increasing serial number.

Elements of the main subgroups, starting from group IV, form gaseous hydrogen compounds. There are four forms of such compounds. They are placed under the elements of the main subgroups and are represented by general formulas in the sequence RH 4 , RH 3 , RH 2 , RH.

RH 4 compounds are neutral; RH 3 - weakly basic; RH 2 - slightly acidic; RH is strongly acidic.

Recall that period call a horizontal row of elements arranged in ascending order of ordinal (atomic) numbers.

Within the period with an increase in the serial number of the element:

• electronegativity increases;
• metallic properties decrease, non-metallic ones increase;
• atomic radius falls.

Elements of the periodic table

Alkaline and alkaline earth elements

These include elements from the first and second groups of the periodic table. alkali metals from the first group - soft metals, silver color well cut with a knife. All of them have a single electron in the outer shell and perfectly react. alkaline earth metals from the second group also have a silver tint. Two electrons are placed at the outer level, and, accordingly, these metals are less willing to interact with other elements. Compared to alkali metals, alkaline earth metals melt and boil at higher temperatures.

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Lanthanides (rare earth elements) and actinides

Lanthanides is a group of elements originally found in rare minerals; hence their name "rare earth" elements. Subsequently, it turned out that these elements are not as rare as they thought at first, and therefore the name lanthanides was given to the rare earth elements. lanthanides and actinides occupy two blocks, which are located under the main table of elements. Both groups include metals; all lanthanides (with the exception of promethium) are non-radioactive; actinides, on the other hand, are radioactive.

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Halogens and noble gases

The halogens and noble gases are grouped into groups 17 and 18 of the periodic table. Halogens represent non-metallic elements, they all have seven electrons in their outer shell. AT noble gases all electrons are in the outer shell, thus hardly participate in the formation of compounds. These gases are called "noble" because they rarely react with other elements; i.e. refer to members of the noble caste who have traditionally shunned other people in society.

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transition metals

transition metals occupy groups 3-12 in the periodic table. Most of them are dense, solid, with good electrical and thermal conductivity. Them valence electrons(through which they are connected to other elements) are in several electron shells.

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transition metals

Scandium Sc 21

Titan Ti 22

Vanadium V 23

Chrome Cr 24

Manganese Mn 25

Iron Fe 26

Cobalt Co27

Nickel Ni 28

Copper Cu 29

Zinc Zn 30

Yttrium Y 39

Zirconium Zr 40

Niobium Nb 41

Molybdenum Mo 42

Technetium Tc 43

Ruthenium Ru 44

Rh 45 rhodium

Palladium Pd 46

Silver Ag 47

Cadmium Cd 48

Lutetium Lu 71

Hafnium Hf 72

Tantalum Ta 73

Tungsten W 74

Rhenium Re 75

Osmium Os 76

Iridium Ir 77

Platinum Pt 78

Gold Au 79

Mercury Hg 80

Lawrencium Lr 103

Rutherfordium Rf 104

Dubnium Db 105

Seaborgium Sg 106

Bory Bh 107

Hassium Hs 108

Meitnerium Mt 109

Darmstadtius Ds 110

X-ray Rg 111

Copernicius Cn 112

Metalloids

Metalloids occupy groups 13-16 of the periodic table. Metalloids such as boron, germanium and silicon are semiconductors and are used to make computer chips and boards.

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Post-transition metals

The elements called fast transition metals , belong to groups 13-15 of the periodic table. Unlike metals, they do not have a shine, but have a matte finish. Compared to transition metals, post-transition metals are softer, have more low temperature melting and boiling, higher electronegativity. Their valence electrons, with which they attach other elements, are located only on the outer electron shell. Elements of the group of post-transition metals have much more high temperature boiling than metalloids.

Flerovium Fl 114 Ununseptius Uus 117

And now consolidate your knowledge by watching a video about the periodic table and more.

Great, the first step on the path to knowledge has been taken. Now you are more or less guided by the periodic table and this will be very useful to you, because the Periodic Table is the foundation on which this amazing science stands.

Metals are the elements that make up the nature around us. As long as the Earth exists, so many metals exist.

The earth's crust contains the following metals:

• aluminum - 8.2%,
• iron - 4.1%,
• calcium - 4.1%,
• sodium - 2.3%,
• magnesium - 2.3%,
• potassium - 2.1%,
• titanium - 0.56%, etc.

On the this moment science has information about 118 chemical elements. Eighty-five of the elements on this list are metals.

Chemical properties of metals

In order to understand what the chemical properties of metals depend on, let's turn to an authoritative source - the table of the periodic system of elements, the so-called. periodic table. Let's draw a diagonal (you can mentally) between two points: start from Be (beryllium) and end at At (astatine). This division is, of course, arbitrary, but it still allows you to combine chemical elements in accordance with their properties. The elements to the left under the diagonal will be metals. The more to the left, relative to the diagonal, the location of the element, the more pronounced its metallic properties will be:

• crystal structure - dense,
• thermal conductivity - high,
• electrical conductivity decreasing with increasing temperature,
• level of the degree of ionization - low (electrons are separated freely)
• ability to form compounds (alloys),
• solubility (dissolve in strong acids and caustic alkalis),
• oxidizability (formation of oxides).

The above properties of metals depend on the presence of electrons freely moving in the crystal lattice. The elements located near the diagonal, or directly at the place of its passage, have dual signs of belonging, i.e. have the properties of metals and non-metals.

The radii of metal atoms are relatively big sizes. Outer electrons, called valence, are significantly removed from the nucleus and, as a result, are weakly bound to it. Therefore, metal atoms easily donate valence electrons and form positively charged ions (cations). This feature is the main chemical property metals. Atoms of elements with the most pronounced metallic properties on the external energy level have from one to three electrons. Chemical elements with characteristically pronounced signs of metals form only positively charged ions, they are not at all capable of attaching electrons.

Displacement series of M. V. Beketov

The activity of the metal and the reaction rate of its interaction with other substances depends on the value of the atom's ability to "part with electrons". The ability is expressed differently in different metals. Elements that have high rates, are active reducing agents. How more mass metal atom, the higher its restorative capacity. The strongest reducing agents are alkali metals K, Ca, Na. If the metal atoms are not able to donate electrons, then such an element will be considered an oxidizing agent, for example: cesium aurid can oxidize other metals. In this regard, alkali metal compounds are the most active.

The Russian scientist M. V. Beketov was the first to study the phenomenon of the displacement of some metals from the compounds formed by them, by other metals. The list of metals compiled by him, in which they are located in accordance with the degree of increase in normal potentials, was called the "electrochemical series of voltages" ( displacement row Beketova).

Li K Rb Cs Ca Na Mg Al Mn Zn Cr Cr Fe Ni Sn Pb Cu Hg Ag Pt Ag Pt Au

The more to the right the metal is located in this row, the lower its reducing properties, and the stronger oxidizing properties its ions.

Classification of metals according to Mendeleev

According to the periodic table, they differ the following types(subgroups) of metals:

• alkaline - Li (lithium), Na (sodium), K (potassium), Rb (rubidium), Cs (cesium), Fr (francium);
• alkaline earth - Be (beryllium), Mg (magnesium), Ca (calcium), Sr (strontium), Ba (barium), Ra (radium);
• light - AL (aluminum), In (indium), Cd (cadmium), Zn (zinc);
• transitional;
• semimetals

Technical application of metals

Metals that have found more or less widespread technical application, are conditionally divided into three groups: black, colored and noble.

To ferrous metals include iron and its alloys: steel, cast iron and ferroalloys.

It should be said that iron is the most common metal in nature. His chemical formula Fe (ferrum). Iron played huge role in human evolution. Man was able to obtain new tools of labor by learning to smelt iron. AT modern industry iron alloys are widely used, obtained by adding carbon or other metals to iron.

Non-ferrous metals - these are almost all metals with the exception of iron, its alloys and noble metals. By their own physical properties non-ferrous metals are classified as follows:

· heavy metals: copper, nickel, lead, zinc, tin;

· lungs metals: aluminum, titanium, magnesium, beryllium, calcium, strontium, sodium, potassium, barium, lithium, rubidium, cesium;

· small metals: bismuth, cadmium, antimony, mercury, cobalt, arsenic;

· refractory metals: tungsten, molybdenum, vanadium, zirconium, niobium, tantalum, manganese, chromium;

· rare metals: gallium, germanium, indium, zirconium;

noble metals : gold, silver, platinum, rhodium, palladium, ruthenium, osmium.

It must be said that people got acquainted with gold much earlier than with iron. Gold jewelry from this metal was made back in Ancient Egypt. Nowadays, gold is also used in microelectronics and other industries.

Silver, like gold, is used in the jewelry industry, microelectronics, and the pharmaceutical industry.

Metals have accompanied man throughout history. human civilization. There is no industry where metals are not used. It is impossible to imagine modern life without metals and their compounds.

Dmitri Mendeleev was able to create a unique table of chemical elements, the main advantage of which was periodicity. Metals and non-metals in the periodic table are arranged in such a way that their properties change in a periodic manner.

The periodic system was compiled by Dmitri Mendeleev in the second half of the 19th century. The discovery not only made it possible to simplify the work of chemists, it was able to combine in itself both in unified system all open chemical substances and predict future discoveries.

The creation of this structured system is priceless for science and for humanity as a whole. It was this discovery that gave impetus to the development of all chemistry for many years.

Interesting to know! There is a legend that ready system dreamed of a scientist in a dream.

In an interview with one journalist, the scientist explained that he had been working on it for 25 years and that he dreamed about it was quite natural, but this does not mean that all the answers came in a dream.

The system created by Mendeleev is divided into two parts:

• periods - horizontal columns in one or two lines (rows);
• groups - vertical lines, in one row.

There are 7 periods in the system, each next element is different from the previous one. large quantity electrons in the nucleus, i.e. the charge of the nucleus of each right indicator is greater than the left one by one. Each period begins with a metal, and ends with an inert gas - this is precisely the periodicity of the table, because the properties of compounds change within one period and repeat in the next. At the same time, it should be remembered that periods 1-3 are incomplete or small, they have only 2, 8 and 8 representatives. AT full period(i.e. the remaining four) 18 chemical representatives each.

In the group are chemical compounds with the same higher , i.e. they have the same electronic structure. A total of 18 groups are represented in the system ( full version), each of which begins with alkali and ends with an inert gas. All substances presented in the system can be divided into two main groups - metal or non-metal.

To facilitate the search, the groups have their own name, and the metallic properties of the substances increase with each lower line, i.e. the lower the connection, the more it will have atomic orbits and the weaker electronic communications. The crystal lattice also changes - it becomes pronounced in elements with a large number of atomic orbits.

In chemistry, three types of tables are used:

1. Short - actinides and lanthanides are taken out of the boundaries of the main field, and 4 and all subsequent periods occupy 2 lines each.
2. Long - in it actinides and lanthanides are taken out of the boundary of the main field.
3. Extra long - each period occupies exactly 1 line.

The main one is considered to be the periodic table, which was adopted and officially confirmed, but for convenience, the short version is more often used. Metals and non-metals in the periodic table are arranged according to strict rules that make it easier to work with.

Metals in the periodic table

In the Mendeleev system, alloys have a predominant number and their list is very large - they start with Boron (B) and end with polonium (Po) (the exceptions are germanium (Ge) and antimony (Sb)). This group has characteristics, they are divided into groups, but their properties are heterogeneous. Their characteristic features:

• plastic;
• electrical conductivity;
• shine;
• easy return of electrons;
• ductility;
• thermal conductivity;
• hardness (except mercury).

Due to different chemical and physical essence properties can differ significantly between two representatives of this group, not all of them are similar to typical natural alloys, for example, mercury is a liquid substance, but belongs to this group.

In its normal state, it is liquid and without crystal lattice who plays key role in alloys. Only chemical characteristics make mercury related to this group of elements, despite the conditionality of the properties of these organic compounds. The same applies to cesium - the softest alloy, but it cannot exist in nature in pure form.

Some elements of this type can exist only for fractions of a second, and some do not occur in nature at all - they were created in artificial conditions laboratories. Each of the metal groups in the system has its own name and features that distinguish them from other groups.

However, their differences are quite significant. In the periodic system, all metals are arranged according to the number of electrons in the nucleus, i.e. by increasing atomic mass. At the same time, they are characterized by a periodic change characteristic properties. Because of this, they are not placed neatly in the table, but may be incorrect.

In the first group of alkalis, there are no substances that would be found in pure form in nature - they can only be in the composition of various compounds.

How to distinguish metal from non-metal?

How to determine the metal in the compound? There is an easy way to determine, but for this you need to have a ruler and a periodic table. To determine you need:

1. Spend conditional line at the junctions of elements from Bor to Polonium (possibly up to Astatine).
2. All materials that will be on the left of the line and in the side subgroups are metal.
3. The substances on the right are of a different type.

However, the method has a flaw - it does not include germanium and antimony in the group and works only in a long table. The method can be used as a cheat sheet, but in order to accurately determine the substance, you should remember a list of all non-metals. How many are there? Few - only 22 substances.

In any case, to determine the nature of a substance, it is necessary to consider it separately. The elements will be easy if you know their properties. It is important to remember that all metals:

1. At room temperature- solid, with the exception of mercury. At the same time, they shine and conduct electricity well.
2. They have a smaller number of atoms at the outer level of the nucleus.
3. Consist of a crystal lattice (except mercury), and all other elements have a molecular or ionic structure.
4. In the periodic table, all non-metals are red, metals are black and green.
5. If you move from left to right in a period, then the charge of the nucleus of matter will increase.
6. Some substances have weak properties, but they still have characteristic features. Such elements belong to semimetals, such as Polonium or Antimony, they are usually located on the border of two groups.

Attention! In the lower left part of the block in the system there are always typical metals, and in the upper right - typical gases and liquids.

It is important to remember that when moving from top to bottom in the table, the non-metallic properties of substances become stronger, since there are elements that have distant outer shells. Their nucleus is separated from the electrons and therefore they are attracted weaker.

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Summing up

It will be easy to distinguish elements if you know the basic principles for the formation of the periodic table and the properties of metals. It will also be useful to memorize the list of the remaining 22 elements. But we must not forget that any element in the compound should be considered separately, not taking into account its bonds with other substances.