PERIODIC TABLE - periodic table of chemical elements

Preface

The periodic table or periodic table of chemical elements is a set of chemical elements presented in table form, which are arranged in ascending order of atomic number.
In each cell of the periodic table there is also a designation of an element, its atomic mass, membership in a certain group indicated by color, and sometimes the electronic configuration is also indicated. The structure of the table shows the periodic nature of the chemical properties of elements. It has 7 rows called periods and columns called groups. It is the columns that combine elements with similar chemical properties. For example, alkali metals, alkaline earth metals, halides, noble gases, etc. There are also four rectangular regions that combine elements with similar electronic structures of their atoms. At the moment, 118 chemical elements have been discovered, which have completed filling seven rows of the table. The first 94 elements were found in nature, although some in very small quantities, but the rest were synthesized artificially in physics laboratories or even during nuclear explosions. Currently, physicists continue attempts to synthesize element 119 and heavier ones; theoretically, the possibility of these elements was proven earlier - they will begin the eighth row of the periodic table. In addition, all elements have so-called isotopes, which were also synthesized in large quantities in laboratories and found in nature. The best known example is heavy water, where hydrogen of atomic weight 1 is replaced by its isotope deuterium (weight 2) or tritium (weight 3).

The structure of the periodic table is used to find the relationship between the properties of various elements and their compounds, as well as to predict these properties, including compounds that have not yet been discovered.

Mendeleev published the first known table in 1869, which demonstrated the periodic nature of the properties of the elements known at that time. Mendeleev also made predictions on the properties of elements that were not discovered at that time, and most of his predictions turned out to be close to correct. Subsequently, with the discovery of other elements, theoretical knowledge expanded, and more and more accurate theoretical mathematical models began to appear to explain and predict the properties of elements.

The modern periodic table is now widely used for the analysis of chemical reactions and is generally widely used in both chemistry and physics. However, there is a lot of debate regarding how optimal this or that type of table is (there are several dozen), as well as the placement of some elements.

How copper was discovered

Metals such as copper, gold, silver and tin have been known to people for a very long time. Because copper is easy to work with, it was used by the oldest known cultures as far back as 10,000 years ago. The peak popularity of copper use dates from the 5th to the 3rd millennium BC. This time in some regions is usually called the “Copper Age”. Both tools and jewelry were made from this metal. On the territory of modern Iran, a copper pendant was found whose age is approximately estimated at 8700 BC. Copper is also the first metal that they learned to alloy with tin and arsenic to bronze. In connection with this discovery, which probably occurred around the 3rd millennium BC, the so-called Bronze Age began. This era lasted approximately until the first millennium BC.

Then copper production and processing began to gain significant momentum. By the beginning of the new era, world copper production varied approximately within 15 tons per year. In the first millennium of our era, massive structures were already produced from copper and its alloys. An example is the bronze statue of Buddha of Nara Temple in Japan. According to historical information, it was cast in 749. To build the 16-meter structure, 400 tons of raw materials were needed. The scientific discovery of the metal itself can be credited to the German scientist Gottfried Hosanne. He invented powder metallurgy, which he used on copper in 1830. During his tests, he described and determined the atomic weight of this chemical element.

Read: Nickel as a chemical element on the periodic table

Introduction

Each chemical element on the periodic table has its own unique atomic number (Z), which is equal to the number of protons in its atomic nucleus. Each atom in the nucleus can have a different number of neutrons and therefore an atom of one element can have a different mass - such “variants” of one atom that differ in mass are called isotopes. For example, the most common isotopes of uranium are U235 and U238, but in fact eight isotopes are currently known with atomic masses from 233 to 240. Isotopes are not separated in the table; it indicates the most common natural isotope or for atoms that do not have stable isotopes , the most stable (long-lived) is indicated.

In the generally accepted periodic table (see above), chemical elements are indicated in increasing order of atomic number Z. A new row (period) begins when a new electron shell of the atom begins to be filled.

Columns (groups) are determined by the electronic configuration of the atom. Elements with the same net number of electrons in the valence electron level fall into the same groups. Elements in the same group usually have similar chemical properties.

The first 94 elements are found in nature in free and bound form or only as compounds, while the rest are synthesized in laboratories. Some elements, for example, francium (Fr), were detected only in the form of radiation (only 300 thousand atoms were received). Other elements above 94 are also obtained in very small quantities.

Decoding the periodic table: how to use

The article discusses the decoding of the periodic table , with which you can quickly understand it. From the periodic table you can glean a huge amount of information about each chemical element . It can be used on the Unified State Exam if you know how to use it correctly.

• Mendeleev's periodic system systematizes elements and their properties. It organizes all the elements based on their atomic number and repeating chemical properties.
• Periodic law : the properties of simple substances, as well as the properties and forms of compounds of elements, are periodically dependent on the charge of the nucleus of the atoms of the elements (ordinal number).

Explanation of element designations

Each chemical element in the table is allocated one cell, in which the symbol and name of the element, serial number and relative atomic mass are indicated.

Decoding the designations of the elements of the periodic table:

• Designation : one or two Latin letters.
• An element's atomic number or atomic number is equal to the number of protons in its nucleus. Usually written in the upper left corner.
• Relative atomic mass (the sum of the masses of protons and neutrons). This is an average value, for the calculation of which the atomic masses of all isotopes of an element are used, taking into account their content in nature. Therefore, it is usually a fractional number.
• 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 it is four.
• The number of positive protons is usually equal to the number of negative electrons in an atom (except in isotopes).
• Electronic configuration is
  a formula for the arrangement of electrons in different electron shells of an atom of a chemical element or molecule.
• To find out the number of neutrons in the nucleus of an element , it is necessary to subtract the atomic number from the relative atomic mass (mass number).

Elements of the periodic table

Metals are located in the lower left corner of the table, non-metals are in the upper right corner. In between are the semimetals . All periods except the first begin with an alkali metal . Each period ends with an inert gas .

• Metals have good electrical and thermal conductivity, are able to reflect bright light, and have a high melting point (they remain solid at normal ambient temperatures, with the exception of mercury).
• Nonmetals occur in nature in three states: gas (such as hydrogen), liquid (such as bromine), and solid (such as phosphorus). It is not capable of conducting heat and electricity. They have a lower melting point compared to metals, and are more brittle and brittle. May have a varied appearance (elements with low density and brightness).
• Metalloids have mixed properties of metals and non-metals (for example, silicon). They have average thermal and electrical conductivity. They differ in melting point, density, color and shape. The appearance may be similar to metals or non-metals.

Decoding groups and periods of the periodic table

In the table, chemical substances are arranged in a special order: from left to right as their atomic masses increase. All of them in the periodic table are combined into periods and groups.

Periods are horizontal rows in a table. All elements of the same period have the same number of energy levels filled with electrons . The number of the period in which the element is located coincides with the number of its valence shell. This valence shell is gradually filled from the beginning to the end of the period.

Regularities of periods:

• Metallic properties decrease, non-metallic and oxidizing properties increase. Each period begins with an active metal and ends with an inert gas.
• The atomic radius decreases .
• Electronegativity increases .

Groups are columns. Elements in all groups have the same electronic structure of their outer electron shells. Each group has the same number of electrons on the outer energy atom, that is, the group number coincides with the number of valence electrons that can participate in the formation of chemical bonds. Therefore, the group number often coincides with the valency of the elements. For example, the group number coincides with the valency of the s-elements and the highest possible valency of the p-elements.

Patterns of groups:

• Metallic properties increase, non-metallic and oxidizing properties decrease.
• The atomic radius of elements within one group increases
• Electronegativity decreases .

The atomic number shows how many protons the nucleus of an element's atom contains and how many electrons the atom has around it. The atom of each subsequent element contains one more proton than the previous one.

Valency

is the property of elements to form chemical bonds.
That is, this is the number of chemical bonds that an atom forms or the number
of atoms that can attach or replace an atom of a given element.
Valency can be: constant and variable (depending on the composition of the substance in which the element is included). Determine valency: – Constant valence is identical to the group number of the main subgroup. Group numbers in the table are shown in Roman numerals. – Variable valence (often the case with non-metals) is determined by the formula: 8 subtract the number of the group in which the substance is located.

Decoding the periods and groups of the periodic table of Mendeleev

Each element has its own serial (atomic) number and is located in a certain period and a certain group.

Periods

• Small periods : first, second and third periods. They contain 2, 8 and 8 elements respectively;
• Large periods : remaining elements. The fourth and fifth periods contain 18 elements, the sixth - 32, and the seventh (not yet completed) - 31 elements.

The table has 7 periods . Each contains a certain number of elements: 1st period - 2 elements (small period), 2nd period - 8 elements (small period), 3rd period - 8 elements (small period), 4th period - 18 elements (large period), 5th period - 18 elements (large period), 6th period - 32 elements (18+14) (large period), 7th period - 32 elements (18+14) (large period) .

Groups and subgroups

• The main subgroups include elements of small periods and elements of large periods with the same properties.
• Side subgroups consist only of elements of large periods. The chemical properties of the elements of the main and secondary subgroups differ significantly.

The periodic table may use different symbols for groups. Therefore, according to this designation, there are different decodings of the groups of the periodic table:

• 18 groups numbered with Arabic numerals.
• 8 groups numbered with the addition of the letters A or B. Groups A are the main subgroups. Groups B are secondary subgroups in large periods. These are only metals. IA, VIIIA - 7 elements each; IIA - VIIA - 6 elements each; IIIB - 32 elements (4+14 lanthanides +14 actinides); VIIIB - 12 elements; IB, IIB, IVB - VIIB - 4 elements each. The Roman group number generally indicates the highest valence in oxides (but does not hold for some elements).

Elements with serial numbers 58–71 (lanthanides) and 90–103 (actinides) are removed from the table and are located below it. These are elements of group IIIB. Lanthanides belong to the sixth period, and actinides to the seventh.

Elements of the main subgroup

Group 1 main subgroup of elements (IA) - alkali metals. These are soft metals, silver in color, easy to cut with a knife. They all have one electron in their outer shell and react well. Lithium Li (3), Sodium Na (11), Potassium K (19), Rubidium Rb (37), Cesium Cs (55), Francium Fr (87).

Group 2 main subgroup (IIA) - alkaline earth metals. They have a silvery tint. Two electrons are placed at the outer level, and, accordingly, these metals interact less readily with other elements. Compared to alkali metals, alkaline earth metals melt and boil at higher temperatures. Calcium Ca (20), Strontium Sr (38), Barium Ba (56), Radium Ra (88).

Group 3 main subgroup (IIIA). All elements of this subgroup, with the exception of boron, are metals. The main subgroup consists of boron, aluminum, gallium, indium and thallium. The outermost electronic level of elements has three electrons. They easily give up these electrons or form three unpaired electrons.

Group 4 main subgroup (IVA). Carbon and silicon have all the properties of non-metals, germanium and tin occupy an intermediate position, and lead has pronounced metallic properties. Most elements of the carbon subgroup are semiconductors (they conduct electricity due to impurities, but worse than metals).

Group 5 main subgroup (VA). The physical properties of the elements of the nitrogen subgroup are different. Nitrogen is a colorless gas. Phosphorus, a soft substance, forms several variants of allotropic modifications - white, red and black phosphorus. Arsenic is a solid semimetal that can conduct electric current. Bismuth is a shiny silvery-white metal with an iridescent tint.

6 group of the main subgroup (VIA). To complete the outer electron level, the atoms of these elements lack only two electrons, so they exhibit strong oxidizing (non-metallic) properties.

Group 7 main subgroup (VIIA) – halogens. (F, Cl, Br, I, At). They have seven electrons in the outer electron layer of the atom. These are strong oxidizing agents that easily react. Halogens (“salt-producing”) are so named because they react with many metals to form salts. The most active of the halogens is fluorine. It is capable of destroying even water molecules, for which it received its formidable name (the word “fluorine” is translated into Russian as “destructive”). And its “close relative” - iodine - is used in medicine in the form of an alcohol solution for treating wounds.

Group 8, main subgroup (VIIIA) – inert (noble) gases. (He, Ne, Ar, Kr, Xe, Rn, Og). Their external electronic level is completely filled. They are practically unable to participate in reactions. That's why they are sometimes called "noble". Inert gases have the ability to glow when exposed to electromagnetic radiation, which is why they are used to create lamps. Thus, neon is used to create luminous signs and advertisements, and xenon is used in car headlights and photo flashes.

Elements of the secondary subgroup

Elements of secondary subgroups except lanthanides and actinides are transition metals. Solid (with the exception of liquid mercury), dense, have a characteristic shine, and conduct heat and electricity well.

Transition metals occupy groups 3–12 on the periodic table. Most of them are dense, hard, with good electrical and thermal conductivity. Their valence electrons (with the help of which they are connected to other elements) are located in several electron shells.

Group 3 - secondary subgroup (IIIB) of the sixth and seventh periods - lanthanides and actinides. For convenience, they are placed under the main table.

• ‍ Lanthanides are sometimes called “rare earths” because they are found in small quantities in rare minerals and do not form their own ores.
• ‍ Actinides have one important common property - radioactivity. All of them, except uranium, are practically not found in nature and are synthesized artificially.

Nonmetals

The upper right corner of the table up to the inert gases are non-metals. Nonmetals conduct heat and electricity poorly and can exist in three states of aggregation: solid (like carbon or silicon), liquid (like bromine) and gaseous (like oxygen and nitrogen). Hydrogen can exhibit both metallic and non-metallic properties, so it is classified in both the first and seventh groups.

Oxygen and hydrogen compounds

All elements except helium, neon and argon form oxygen compounds. There are 8 forms of oxygen compounds: R2O, RO, R2O3, RO2, R2O5, RO3, R2O7, RO4, where R is a group element.

Elements of the main subgroups, starting from group IV, form gaseous hydrogen compounds . There are 4 forms of hydrogen compounds: RH4, RH3, RH2, RH. Nature of the compounds: RH - strongly acidic; RH2 - slightly acidic; RH3 - weakly basic; RH4 – neutral.

Metals, metalloids and non-metals

According to their physical and chemical properties, all elements can be divided into three main categories - metals, metalloids and non-metals.

Metals are generally shiny, highly thermally conductive solids that can melt when heated and form alloys with each other, as well as form ionic and covalent compounds with nonmetals.

Nonmetals are usually colorless or colored solid, liquid or gaseous substances. Nonmetals form compounds with each other using covalent bonds.

Metalloids are substances that can exhibit both metallic and non-metallic properties under certain conditions.

Metals and non-metals can be further classified into subcategories, which are visible in the table in rows from left to right. Thus, metals are divided into chemically very active alkali metals, slightly less active alkaline earth metals, characteristic transition metals and chemically quite inert post-transition metals.

Nonmetals are divided into polyatomic nonmetals, and they are closer to metalloids because sometimes exhibit metallic properties on halides and inert gases. The proportion of nonmetals among all elements is small - there are 19 of them out of 118 known elements.

In fact, such a division, even within each category, is very arbitrary and there is a large “overlap” at these conventional boundaries. For example, beryllium is an alkaline earth element, but its amphoteric nature and tendency to form covalent compounds make it a post-transition metal. Radon is a noble gas, but forms a number of ionic compounds characteristic of metals. Therefore, there are other types of division of elements into groups, for example, according to mineralogical characteristics or crystal structures of compounds.

Alkali and alkaline earth metals

The two categories are very similar to each other, but the alkaline earth metals are less reactive. They all form basic oxides. They are characterized by low mechanical strength, all alkali metals are easily cut with a knife, very high chemical activity (for example, potassium, and even more so rubidium, can ignite directly in air, and react with water with an “explosion” - the reaction is so fast that a pop is heard ). Magnesium and beryllium are harder and much less reactive, so they are sometimes used in pure form or in the form of alloys (magnesium-aluminum alloy is very important in the aviation industry, for example).

Where and how is copper mined?

As it becomes clear from the text above, such a chemical element as copper has been used since ancient times. And the extraction of this element was already carried out before our era. Copper is the third most commonly used metal after iron and aluminum. All copper ore mined before 1900 represents less than 5% of all ore extracted from the bowels of the Earth. In 2008, copper production exceeded the threshold of 15 million tons per year. Today, this figure is preparing to exceed the 20 million tons mark. The leading copper producers are Chile, Peru, China, USA, Congo, Australia, Zambia, Indonesia, Mexico and Russia.

The process of obtaining copper itself is as follows. First, Cu2S copper stone is extracted from CuFeS2 copper gravel. To do this, gravel is fired with the addition of coke, and iron oxides are slagged with silica. Iron silicate slag floats on the surface and can be easily drained. The copper stone remaining at the bottom is then processed into blister copper. This procedure is usually carried out in two stages. In the first stage, the resulting iron sulfide is burned to form iron oxide and binds with quartz slag, which is subsequently poured out. In the second stage, two-thirds of the copper stone is oxidized to oxide. Copper oxide then reacts with the remaining sulfide to form blister copper.

Blister copper has a purity of about 98%, and the remaining 2% comes from impurities of iron, zinc, silver and gold. Purification of blister copper is carried out by electrolytic refining in sulfuric acid. During this reaction, iron and zinc are dissolved as cations, and noble metals are deposited at the bottom. The copper output from this process is 99.99% pure.

Read: Cobalt as a chemical element on the periodic table

Transition metals

This group has a very wide range of physical and chemical properties. For example, the melting point of mercury is -38.8 ºC, and that of yttrium is 1795 ºC. Also, hardness, density, and chemical activity are in a very wide range (for example, the noble metal gold is very chemically inert, but zinc, on the contrary, is very reactive and in this indicator is closer to the alkaline earth elements). Metals of this group are the basis of all industrial production and spheres of life. They are used in all industries - from structural materials to the microelectronics industry.

Halogens

Group VIIA(17) . Atoms of elements of this group usually receive one electron each, because There are five elements on the outer electronic layer and one electron is just missing from the “full set”.

The most well-known elements of this group: chlorine (Cl) - is part of salt and bleach; Iodine (I) is an element that plays an important role in the activity of the human thyroid gland.

Electronic Configuration:

• F - 1s22s22p5;
• Cl - 1s22s22p63s23p5;
• Br - 1s22s22p63s23p64s23d104p5

For more information about halogens, see Atoms of group VII elements: general characteristics...

Nonmetals (reactive)

Under normal conditions, boron, carbon, phosphorus, sulfur, and selenium are solids of various colors. Each of them has different forms of crystal lattice (allotropic modifications), for example red, yellow, black, white phosphorus, which greatly affects their chemical activity (for example, graphite is much less active than ordinary coal) and physical properties (diamond is the hardest substance in nature and is a transparent material, while graphite is brittle, soft, opaque).

Nitrogen and oxygen are gases. At the same time, nitrogen is quite chemically inert, oxygen, on the contrary, is a very active oxidizing agent.

Halides have different physical properties (fluorine, chlorine are gases, bromine is a liquid, iodine is a solid). Astatine is obtained only in extremely small quantities, like tennessine, their properties are poorly studied. Chemically, halides are very strong oxidizing agents (fluorine is the strongest on the periodic table). With metals they usually form salts with an ionic lattice, and with hydrogen they form very strong acids. With nonmetals they also form many polyatomic compounds, usually with covalent bonds.

Formulation of the periodic law of chemical elements

The Russian scientist drafted the table for about 20 years, trying to find the right pattern in their placement. Noting the concept of cyclicity, he turned it into a periodic law, outlining his understanding of the rule:

“The properties of elements, as well as the simple and complex substances they form, imply a periodic dependence on their atomic weight.”

The development of science during the 20th century slightly modified the law: the term “atomic weight” was replaced by “charge of the nucleus of an atom”, instead of “simple and complex substances” - “substances and compounds”, the definition “chemical” was added to the elements.

Non-metals (inert gases)

Extremely chemically passive substances. The first xenon compound, XePtF6, was synthesized in 1962, but neon and helium compounds are still unknown. Nevertheless, inert gases play a huge role in various industries, medicine, diving, etc.

PS: It’s interesting that the name “Mendeleev’s Table” is known mainly only in Russia, while in the rest of the world it is most often called simply “Periodic Table”.

PPS: The article will be supplemented and corrected.

Interesting Facts

Since the use of copper is very wide, there are, accordingly, a lot of interesting facts related to copper. It’s worth starting with the fact that the price of pure copper on the world market is not so low. In 2014, 1 ton of copper on the world market was valued at 7,000 US dollars. Due to such a high price, the number of thefts of copper items has increased. For example, in Germany, the railway company Deutsche Bahn AG suffered losses of 14 million euros due to the theft of copper grounding cables.

Another interesting point is that the first mirrors invented by man were made of copper. The copper was rubbed (polished) until a reflection on the surface of the copper was visible. Also in the field of application, it is worth noting that most of the coins produced around the world contain copper. Another interesting fact is that copper, like iron and aluminum, can be recycled without losing its properties.

The biological component of copper can also be noted. In large quantities it is toxic, but in small quantities it is an integral part of the existence of the human body. In various states, the human body contains about 150 mg of copper. The normal daily intake of copper for a person weighing 75 kg is 2 mg.