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

See also: List of chemical elements by symbol and Alphabetical list of chemical elements This is a list of chemical elements arranged in order of increasing atomic number. The table shows the name of the element, symbol, group and period in... ... Wikipedia

Main article: Lists of chemical elements Contents 1 Electronic configuration 2 References 2.1 NIST ... Wikipedia

Main article: Lists of chemical elements No. Symbol Name Mohs hardness Vickers hardness (GPa) Brinnell hardness (GPa) 3 Li Lithium 0.6 4 Be Beryllium 5.5 1.67 0.6 5 B Boron 9.5 49 6 C Carbon 1.5 (graphite) 6...Wikipedia

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

Main article: Lists of chemical elements No. Symbol Russian name Latin name Etymology of the name 1 H Hydrogen Hydrogenium From other Greek. ὕδωρ “water” and γεννάω “I give birth.” 2 ... Wikipedia

List of symbols of chemical elements are symbols (signs), codes or abbreviations used for a brief or visual representation of the names of chemical elements and simple substances of the same name. First of all, these are symbols of chemical elements ... Wikipedia

Below are the names of erroneously discovered chemical elements (indicating the authors and dates of discovery). All of the elements mentioned below were discovered as a result of experiments carried out more or less objectively, but usually incorrectly... ... Wikipedia

Recommended values ​​for many element properties, along with various references, are collected on these pages. Any changes in the values ​​​​in the infobox must be compared with the given values ​​​​and / or given accordingly ... ... Wikipedia

Chemical symbol of a diatomic chlorine molecule 35 Symbols of chemical elements (chemical symbols) symbol of chemical elements. Together with chemical formulas, diagrams and equations of chemical reactions they form a formal language... ... Wikipedia

Books

• Japanese-English-Russian dictionary for installation of industrial equipment. About 8,000 terms, Popova I.S.. The dictionary is intended for a wide range of users and primarily for translators and technical specialists involved in the supply and implementation of industrial equipment from Japan or...
• English for doctors. 8th ed. , Muraveyskaya Marianna Stepanovna, Orlova Larisa Konstantinovna. 384 pp. The purpose of the textbook is to teach reading and translating English medical texts, conducting conversations in various areas of medicine. It consists of a brief introductory phonetic and...

Silicon(lat. Silicium), Si, 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%).

Historical reference. K compounds, widespread 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 - production glass- began around 3000 BC. e. (in Ancient Egypt). The earliest known compound of K. 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. For the first time, in 1825, he obtained elemental silicon from silicon fluoride SiF 4, reducing the latter with potassium metal. The new element was given the name “silicon” (from the Latin silex - flint). The Russian name was introduced by G.I. Hess in 1834.

Prevalence in nature. In terms of prevalence in the earth's crust, oxygen is the second element (after oxygen), 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 the animal and plant world. For the geochemistry of oxygen, its extremely strong connection with oxygen is important. About 12% of the lithosphere is silica SiO 2 in the form of the mineral quartz and its varieties. 75% of the lithosphere consists 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, weak differentiation of calcium 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. Its migration with water vapor is also possible, therefore pegmatites of hydrothermal veins are characterized by significant concentrations of quartz, which is often associated with ore elements (gold-quartz, quartz-cassiterite, etc. veins).

Physical and chemical properties. C. forms dark gray crystals with a metallic luster, having a face-centered cubic diamond-type lattice with a period A= 5.431Å, density 2.33 g/cm 3 . At very high pressures, a new (apparently hexagonal) modification with a density of 2.55 was obtained g/cm 3 . 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. is diamagnetic, atomic magnetic susceptibility is -0.13×10 -6. K hardness 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 coefficient 0.325×10 -6 cm 2 /kg. K. brittle material; noticeable plastic deformation begins at temperatures above 800°C.

K. is a semiconductor that is finding increasing use. The electrical properties of copper are very dependent on impurities. The intrinsic specific volumetric electrical resistivity of a cell at room temperature is taken to be 2.3 × 10 3 ohm× m(2.3×10 5 ohm× cm).

Semiconductor circuit with conductivity R-type (additives B, Al, In or Ga) and n-type (additives P, Bi, As or Sb) has significantly 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 the ring in the periodic table of Mendeleev, the 14 electrons of the ring 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 carbon compounds (similar to carbon) 4-valentene. However, unlike carbon, silica, along with a coordination number of 4, exhibits a coordination number of 6, which is explained by the large volume of its atom (an example of such compounds are silicofluorides containing the 2- group).

The chemical bond of a carbon atom 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. Having a low electronegativity value of 1.8 (versus 2.5 for carbon; 3.0 for nitrogen, etc.), carbon is electropositive in compounds with nonmetals, and these compounds are polar in nature. High binding energy with oxygen Si-O, equal to 464 kJ/mol(111 kcal/mol), determines the stability of its oxygen compounds (SiO 2 and silicates). Si-Si bond energy is low, 176 kJ/mol (42 kcal/mol); Unlike carbon, silicon is not characterized by the formation of long chains and double bonds between Si atoms. In air, due to the formation of a protective oxide film, carbon is stable even at elevated temperatures. In oxygen it oxidizes starting at 400°C, forming silicon dioxide SiO2. Monoxide SiO is also known, stable at high temperatures in the form of a gas; as a result of sudden cooling, a solid product can be obtained that 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 the release 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 react directly with carbon, and silicic acids(silanes) are obtained by decomposition of silicides (see below). Hydrogen silicones are known from SiH 4 to Si 8 H 18 (the composition is similar to saturated hydrocarbons). K. forms 2 groups of oxygen-containing silanes - siloxanes and siloxenes. K reacts with nitrogen at temperatures above 1000°C. Of great practical importance is Si 3 N 4 nitride, which does not oxidize in air even at 1200°C, is resistant to acids (except nitric) and alkalis, as well as molten metals and slags, which makes it a valuable material for the chemical industry, for production of refractories, etc. Compounds of carbon with carbon are distinguished by their high hardness, as well as thermal and chemical resistance ( silicon carbide SiC) and with boron (SiB 3, SiB 6, SiB 12). When heated, chlorine reacts (in the presence of metal catalysts, such as copper) with organochlorine compounds (for example, CH 3 Cl) to form organohalosilanes [for example, Si (CH 3) 3 CI], which are used for the synthesis of numerous organosilicon compounds.

K. forms compounds with almost all metals - silicides(compounds only with Bi, Tl, Pb, Hg were not detected). 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 refractory and hard; Ferrosilicon is of 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%) is 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 copper. This requires the preliminary synthesis of the purest starting compounds of copper, from which copper is extracted by reduction or thermal decomposition.

Pure semiconductor copper 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-crystalline (crucible-free zone melting and “pulling” a single crystal from molten copper - the Czochralski method).

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

K. has diverse and ever-expanding areas of application. In metallurgy, oxygen is used to remove oxygen dissolved in molten metals (deoxidation). K. is a component of a large number of alloys of iron and non-ferrous metals. Usually, carbon gives alloys increased resistance to corrosion, improves their casting properties, and increases mechanical strength; however, with a higher content of K. it can cause fragility. The most important are iron, copper, and aluminum alloys containing calcium. An increasing amount of carbon is used for the synthesis of organosilicon compounds and silicides. Silica and many silicates (clays, feldspars, mica, talc, etc.) are processed by the glass, cement, ceramic, electrical, and other industries.

V. P. Barzakovsky.

Silicon is found in the body in the form of various compounds, mainly involved in the formation of hard skeletal parts and tissues. Some marine plants (for example, diatoms) and animals (for example, siliceous sponges, radiolarians) can accumulate especially large amounts of silicon, forming thick deposits of silicon dioxide on the ocean floor when they die. In cold seas and lakes, biogenic silts enriched in potassium predominate; in tropical seas, calcareous silts with a low content of potassium predominate. Among land plants, cereals, sedges, palms, and horsetails accumulate a lot of potassium. 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. When there is a high content of silicon dioxide dust in the air, it enters the human lungs and causes disease - silicosis.

V. V. Kovalsky.

Lit.: Berezhnoy A.S., 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. Levinzon, V. 1-2, M., 1969-70; Gladyshevsky E.I., Crystal chemistry of silicides and germanides, M., 1971; Wolf N. F., Silicon semiconductor data, Oxf. - N.Y., 1965.

If you find the periodic table difficult to understand, you are not alone! Although it can be difficult to understand its principles, learning how to use it will help you when studying science. First, study the structure of the table and what information you can learn from it about each chemical element. Then you can begin to study 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

The periodic table, or periodic table of chemical elements, begins in the upper left corner and ends at the end of the last row of the table (lower right corner). The elements in the table are arranged from left to right in increasing order of their atomic number. The atomic number shows how many protons are contained in one atom. In addition, as the atomic number increases, the atomic mass also increases. Thus, by the location of an element in the periodic table, its atomic mass can be determined.

1. As you can see, each subsequent 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. Because elements are arranged in groups, some table cells are left 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 located on opposite edges because they belong to different groups.

2. Learn about groups that contain elements with similar physical and chemical properties. The elements of each group are located in the corresponding vertical column. They are typically identified by the same color, which helps 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 their outer shell.

   • Hydrogen can be classified as both alkali metals and 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 specified in Roman (eg IA) or Arabic (eg 1A or 1) numerals.
   • When moving along a column from top to bottom, you are said to be “browsing a group.”

3. Find out why there are empty cells in the table. Elements are ordered not only according to their atomic number, but also by group (elements in the same group have similar physical and chemical properties). Thanks to this, it is easier to understand how a particular 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 because transition metals are only found from atomic number 21.
   • Elements with atomic numbers 57 to 102 are classified as rare earth elements, and are usually placed in their own 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 the electrons in the atoms are located. The number of orbitals corresponds to the period number. The table contains 7 rows, that is, 7 periods.

   • For example, atoms of elements of the first period have one orbital, and atoms of elements of the seventh period have 7 orbitals.
   • As a rule, periods are designated 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 the 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 is. For convenience, in most tables metals, metalloids, and nonmetals are designated 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 a shortened name for an element that is the same in most languages. Element symbols are commonly used when conducting experiments and working with chemical equations, so it is helpful to remember them.

      • Typically, element symbols are abbreviations of their Latin name, although for some, especially recently discovered elements, they are derived from the common name. For example, helium is represented 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 element "name" is used in regular texts. For example, "helium" and "carbon" are names of elements. Usually, although not always, the full names of the elements are listed below their chemical symbol.

      • Sometimes the table does not indicate the names of the elements and only gives their chemical symbols.

   3. Find the atomic number. Typically, the atomic number of an element is located at the top of the corresponding cell, in the middle or in the corner. It may also appear under the element's symbol or 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, you would get a different chemical element!

      • The atomic number of an element can also 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. Because 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 an electrical charge. If an ion has more protons, it has a 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, indicated by a minus sign.
      • The plus and minus signs are not used if the atom is not an ion.

How to use the periodic table? For an uninitiated person, reading the periodic table is the same as for a gnome looking at the ancient runes of the elves. And the periodic table can tell you a lot about the world.

In addition to serving you well in the exam, it is also simply irreplaceable in solving a huge number of chemical and physical problems. But how to read it? Fortunately, today everyone can learn this art. In this article we will tell you how to understand the periodic table.

The periodic table of chemical elements (Mendeleev's table) is a classification of chemical elements that establishes the dependence of various properties of elements on the charge of the atomic nucleus.

History of the creation of the Table

Dmitry Ivanovich Mendeleev was not a simple chemist, if anyone thinks so. He was a chemist, physicist, geologist, metrologist, ecologist, economist, oil worker, aeronaut, instrument maker and teacher. During his life, the scientist managed to conduct a lot of fundamental research in various fields of knowledge. For example, it is widely believed that it was Mendeleev who calculated the ideal strength of vodka - 40 degrees.

We don’t know how Mendeleev felt about vodka, but we know for sure that his dissertation on the topic “Discourse on the combination of alcohol with water” had nothing to do with vodka and considered alcohol concentrations from 70 degrees. With all the merits of the scientist, the discovery of the periodic law of chemical elements - one of the fundamental laws of nature, brought him the widest fame.

There is a legend according to which a scientist dreamed of the periodic table, after which all he had to do was refine the idea that had appeared. But, if 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, but you think: I was sitting there and suddenly... it’s done.”

In the mid-nineteenth century, attempts to arrange the known chemical elements (63 elements were known) were undertaken in parallel by several scientists. For example, in 1862, Alexandre Emile Chancourtois placed elements along a helix and noted the cyclic repetition of chemical properties.

Chemist and musician John Alexander Newlands proposed his version of the periodic table in 1866. An interesting fact is that the scientist tried to discover some kind of mystical musical harmony in the arrangement of the elements. Among other attempts, there was also Mendeleev’s attempt, which was crowned with success.

In 1869, the first table diagram was published, and March 1, 1869 is considered the day the periodic law was opened. The essence of Mendeleev's discovery was that the properties of elements with increasing atomic mass do not change monotonically, but periodically.

The first version of the table contained only 63 elements, but Mendeleev made a number of very unconventional decisions. So, he guessed to leave space in the table for still undiscovered elements, and also changed the atomic masses of some elements. The fundamental correctness of the law derived by Mendeleev was confirmed very soon, after the discovery of gallium, scandium and germanium, the existence of which was predicted by the scientist.

Modern view of the periodic table

Below is the table itself

Today, instead of atomic weight (atomic mass), the concept of atomic number (the number of protons in the nucleus) is used to order elements. The table contains 120 elements, which are arranged from left to right in order of increasing atomic number (number of protons)

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

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

What do we learn about an element from the table? For example, let's take the third element in the table - lithium, and consider it in detail.

First of all, we see the element symbol itself and its name below it. In the upper left corner is the atomic number of the element, in which order the element is arranged in the table. The atomic number, as already mentioned, 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 (except in isotopes).

The atomic mass is indicated under the atomic number (in this version of the table). If we round the atomic mass to the nearest integer, we get what is called the mass number. The difference between the mass number and the atomic number gives the number of neutrons in the nucleus. Thus, the number of neutrons in a helium nucleus is two, and in lithium it is four.

Our course “Periodical Table for Dummies” has ended. In conclusion, we invite you to watch 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 it is always more effective to study a new subject 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 its knowledge and experience with you.

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

See also: List of chemical elements by symbol and Alphabetical list of chemical elements This is a list of chemical elements arranged in order of increasing atomic number. The table shows the name of the element, symbol, group and period in... ... Wikipedia

- (ISO 4217) Codes for the representation of currencies and funds (English) Codes pour la représentation des monnaies et types de fonds (French) ... Wikipedia

The simplest form of matter that can be identified by chemical methods. These are components of simple and complex substances, representing a collection of atoms with the same nuclear charge. The charge of the nucleus of an atom is determined by the number of protons in... Collier's Encyclopedia

Contents 1 Paleolithic era 2 10th millennium BC. e. 3 9th millennium BC uh... Wikipedia

Contents 1 Paleolithic era 2 10th millennium BC. e. 3 9th millennium BC uh... Wikipedia

This term has other meanings, see Russian (meanings). Russians... Wikipedia

Terminology 1: : dw Number of the day of the week. “1” corresponds to Monday Definitions of the term from various documents: dw DUT The difference between Moscow and UTC time, expressed as an integer number of hours Definitions of the term from ... ... Dictionary-reference book of terms of normative and technical documentation