Chemistry elements periodic table. Alphabetical list of chemical elements

If the periodic table seems difficult for you to understand, you are not alone! Although it can be difficult to understand its principles, knowing how to work with it will help in learning 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

periodic table, or periodic system chemical elements, starts at the top left and ends at the end of the last row 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.

1. 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.

2. 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".

3. 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.

4. 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".

5. 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.

      • Usually, element symbols are shorthand for their Latin name, although for some, especially recently open 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 below 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!

      • The atomic number of an element can also be used to determine the number of electrons and neutrons in an atom.

   5. Usually the number of electrons is equal to the number of protons. The exception is the case when the atom is ionized. Protons have a positive charge and electrons have a negative charge. Since atoms are usually neutral, they contain the same number of electrons and protons. However, an atom can gain or lose electrons, in which case it becomes ionized.

      • Ions have electric charge. If there are more protons in an ion, then it has positive charge, in which case a plus sign is placed after the element symbol. If an ion contains more electrons, it has a negative charge, which is indicated by a minus sign.
      • The plus and minus signs are omitted if the atom is not an ion.

Silicon(lat. Silicium), Si, a chemical element of group IV of the periodic system of Mendeleev; atomic number 14, atomic mass 28.086. In nature, the element is represented by three stable isotopes: 28 Si (92.27%), 29 Si (4.68%) and 30 Si (3.05%).

History reference. K. compounds, widely distributed on earth, have been known to man since the Stone Age. The use of stone tools for labor and hunting continued for several millennia. The use of K. compounds associated with their processing is the manufacture glass began around 3000 BC. e. (in Ancient Egypt). The earliest known K. compound is SiO 2 dioxide (silica). In the 18th century silica was considered a simple body and referred to as "earths" (which is reflected in its name). The complexity of the composition of silica was established by I. Ya. Berzelius. In 1825, he was also the first to obtain elemental K. from silicon fluoride SiF 4 , reducing the latter with metallic potassium. The new element was given the name "silicon" (from the Latin silex - flint). Russian name introduced G.I. hess in 1834.

distribution in nature. In terms of prevalence in earth's crust K. is the second (after oxygen) element, its average content in the lithosphere is 29.5% (by mass). In the earth's crust, carbon plays the same primary role as carbon in animals and flora. For the geochemistry of oxygen, its exceptionally strong bond with oxygen is important. About 12% of the lithosphere is silica SiO 2 in the form of a mineral quartz and its varieties. 75% of the lithosphere is composed of various silicates And aluminosilicates(feldspars, micas, amphiboles, etc.). The total number of minerals containing silica exceeds 400 (see Fig. silica minerals).

During magmatic processes, a slight differentiation of rock occurs: it accumulates both in granitoids (32.3%) and in ultrabasic rocks (19%). At high temperatures and high pressure, the solubility of SiO 2 increases. It can also migrate with water vapor; therefore, pegmatites of hydrothermal veins are characterized by significant concentrations of quartz, with which ore elements are often associated (gold-quartz, quartz-cassiterite, and other veins).

Physical and Chemical properties. K. forms dark gray crystals with a metallic luster, having a cubic face-centered lattice of the diamond type with a period but= 5.431Å, density 2.33 g/cm3. At very high pressures, a new (apparently hexagonal) modification with a density of 2.55 g/cm3. K. melts at 1417°C, boils at 2600°C. Specific heat capacity (at 20-100°C) 800 j/(kg× TO), or 0.191 cal/(G× hail); thermal conductivity even for the purest samples is not constant and is in the range (25°C) 84-126 Tue/(m× TO), or 0.20-0.30 cal/(cm× sec× hail). Temperature coefficient of linear expansion 2.33×10 -6 K -1 ; below 120K becomes negative. K. is transparent to long-wave infrared rays; refractive index (for l =6 µm) 3.42; dielectric constant 11.7. K. diamagnetic, atomic magnetic susceptibility -0.13×10 -6. Hardness K. according to Mohs 7.0, according to Brinell 2.4 Gn/m 2 (240 kgf/mm 2), modulus of elasticity 109 Gn/m 2 (10890 kgf/mm 2), compressibility factor 0.325×10 -6 cm 2 /kg. K. fragile material; noticeable plastic deformation begins at temperatures above 800°C.

K. is a semiconductor that is increasingly used. The electrical properties of K. depend very strongly on impurities. The intrinsic specific volume electrical resistance of K. at room temperature is assumed to be 2.3 × 10 3 ohm× m(2.3×10 5 ohm× cm).

Semiconductor K. with conductivity R-type (additives B, Al, In or Ga) and n-type (additives P, Bi, As or Sb) has a much lower resistance. The band gap according to electrical measurements is 1.21 ev at 0 TO and decreases to 1.119 ev at 300 TO.

In accordance with the position of K. in the periodic system of Mendeleev, 14 electrons of the K. atom are distributed over three shells: in the first (from the nucleus) 2 electrons, in the second 8, in the third (valence) 4; electron shell configuration 1s 2 2s 2 2p 6 3s 2 3p 2(cm. Atom). Successive ionization potentials ( ev): 8.149; 16.34; 33.46 and 45.13. Atomic radius 1.33Å, covalent radius 1.17Å, ionic radii Si 4+ 0.39Å, Si 4- 1.98Å.

In compounds K. (similar to carbon) is 4-valent. However, unlike carbon, along with a coordination number of 4, carbon exhibits a coordination number of 6, which is explained by the large volume of its atom (silicofluorides containing the 2- group are an example of such compounds).

chemical bond Atom K. with other atoms is usually carried out due to hybrid sp 3 orbitals, but it is also possible to involve two of its five (vacant) 3 d- orbitals, especially when K. is six-coordinate. Possessing a low electronegativity value of 1.8 (versus 2.5 for carbon; 3.0 for nitrogen, etc.), K. in compounds with non-metals is electropositive, and these compounds are polar in nature. Large bonding energy with oxygen Si-O, equal to 464 kJ/mol(111 kcal/mol), determines the resistance of its oxygen compounds (SiO 2 and silicates). The Si-Si binding energy is low, 176 kJ/mol (42 kcal/mol); unlike carbon, the formation of long chains and a double bond between Si atoms is not characteristic of carbon. Owing to the formation of a protective oxide film, oxygen is stable in air even at elevated temperatures. Oxidizes in oxygen starting from 400°C, forming silicon dioxide SiO2. Also known is the monoxide SiO, which is stable at high temperatures in the form of a gas; as a result of rapid cooling, a solid product can be obtained, which easily decomposes into a thin mixture of Si and SiO 2 . K. is resistant to acids and dissolves only in a mixture of nitric and hydrofluoric acids; easily dissolves in hot alkali solutions with evolution of hydrogen. K. reacts with fluorine at room temperature, with other halogens - when heated to form compounds of the general formula SiX 4 (see. Silicon halides). Hydrogen does not directly react with oxygen, and silicon hydrogens(silanes) are obtained by decomposition of silicides (see below). Silicon hydrogens are known from SiH 4 to Si 8 H 18 (similar in composition to saturated hydrocarbons). K. forms 2 groups of oxygen-containing silanes - siloxanes and siloxenes. K. reacts with nitrogen at temperatures above 1000°C. Important practical value has Si 3 N 4 nitride, which does not oxidize in air even at 1200°C, is resistant to acids (except nitric acid) and alkalis, as well as to molten metals and slags, which makes it a valuable material for chemical industry, for the production of refractories, and others. High hardness, as well as thermal and chemical resistance, are distinguished by compounds of K. with carbon ( silicon carbide SiC) and with boron (SiB 3, SiB 6, SiB 12). When heated, K. reacts (in the presence of metal catalysts, such as copper) with organochlorine compounds (for example, with CH 3 Cl) to form organohalosilanes [for example, Si (CH 3) 3 CI], which are used to synthesize numerous organosilicon compounds.

K. forms compounds with almost all metals - silicides(no compounds were found only with Bi, Tl, Pb, Hg). More than 250 silicides have been obtained, the composition of which (MeSi, MeSi 2 , Me 5 Si 3 , Me 3 Si, Me 2 Si, etc.) usually does not correspond to classical valencies. Silicides are distinguished by their infusibility and hardness; ferrosilicon is of the greatest practical importance (a reducing agent in the smelting of special alloys, see Ferroalloys) and molybdenum silicide MoSi 2 (electric furnace heaters, gas turbine blades, etc.).

Receipt and application. K. of technical purity (95-98%) are obtained in an electric arc by the reduction of silica SiO 2 between graphite electrodes. In connection with the development of semiconductor technology, methods have been developed for obtaining pure and especially pure potassium. This requires the preliminary synthesis of the purest starting compounds of potassium, from which the potassium is extracted by reduction or thermal decomposition.

Pure semiconductor K. is obtained in two forms: polycrystalline (by reduction of SiCI 4 or SiHCl 3 with zinc or hydrogen, thermal decomposition of Sil 4 and SiH 4) and single-crystal (by crucibleless zone melting and "pulling" a single crystal from molten K. - the Czochralski method).

Specially alloyed K. is widely used as a material for the manufacture of semiconductor devices (transistors, thermistors, power rectifiers, controllable diodes - thyristors; solar photocells used in spaceships, etc.). Since K. is transparent to rays with a wavelength from 1 to 9 micron, it is used in infrared optics (see also Quartz).

K. has diverse and ever-expanding fields of application. In metallurgy oxygen is used to remove oxygen dissolved in molten metals (deoxidation). K. is integral part a large number of iron alloys and non-ferrous metals. K. Usually gives alloys increased resistance to corrosion, improves their casting properties and increases mechanical strength; however, with a higher content of K., it can cause brittleness. Iron, copper, and aluminum alloys containing sulfuric acid are of the greatest importance. An increasing amount of sulfuric acid is used for the synthesis of organosilicon compounds and silicides. Silica and many silicates (clays, feldspars, micas, talcs, etc.) are processed by the glass, cement, ceramics, electrical engineering, and other branches of industry.

V. P. Barzakovsky.

Silicon in the body is found in the form of various compounds, which are mainly involved in the formation of solid skeletal parts and tissues. Certain marine plants (for example, diatoms) and animals (for example, silicon-horned sponges and radiolarians) can accumulate especially large amounts of oxygen, which, when they die, form thick deposits of silicon dioxide on the ocean floor. In cold seas and lakes, biogenic silts enriched with calcium predominate; in tropical seas, calcareous silts with a low content of calcium predominate. In vertebrates, the content of silicon dioxide in ash substances is 0.1-0.5%. In the largest quantities, K. is found in dense connective tissue, kidneys, and pancreas. The daily human diet contains up to 1 G K. With a high content of silicon dioxide dust in the air, it enters the lungs of a person and causes disease - silicosis.

V. V. Kovalsky.

Lit.: Berezhnoy AS, Silicon and its binary systems. K., 1958; Krasyuk B. A., Gribov A. I., Semiconductors - germanium and silicon, M., 1961; Renyan V. R., Technology of semiconductor silicon, trans. from English, M., 1969; Sally I. V., Falkevich E. S., Production of semiconductor silicon, M., 1970; silicon and germanium. Sat. Art., ed. E. S. Falkevich, D. I. Levinson, c. 1-2, M., 1969-70; Gladyshevsky E. I., Crystal chemistry of silicides and germanides, M., 1971; Wolf H. F., Silicon semiconductor data, Oxf. - N. Y., 1965.

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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 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 periodic law 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.

1. The metallic properties of elements decrease when moving along the period from left to right, and in reverse direction- increase.
2. The dimensions of atoms decrease as they move from left to right along the periods.
3. When moving from top to bottom in the group, the reducing metallic properties increase.
4. Oxidizing and non-metallic properties increase along the period from left to right.

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 suggest you watch a thematic video, and we hope that the question of how to use periodic table Mendeleev, became more understandable 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 the student service, which will gladly share their knowledge and experience with you.

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