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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
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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
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Periodic table of chemical elements (periodic table)- classification of chemical elements, establishing the dependence of various properties of elements on the charge of the atomic nucleus. The system is a graphic expression of the periodic law established by the Russian chemist D. I. Mendeleev in 1869. Its original version was developed by D.I. Mendeleev in 1869-1871 and established the dependence of the properties of elements on their atomic weight (in modern terms, on atomic mass). In total, several hundred options for depicting the periodic system (analytical curves, tables, geometric figures, etc.) have been proposed. In the modern version of the system, it is assumed that elements are summarized in a two-dimensional table, in which each column (group) defines the main physical and chemical properties, and the rows represent periods that are to a certain extent similar to each other.
Periodic table of chemical elements by D.I. Mendeleev
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The discovery made by the Russian chemist Mendeleev played (by far) the most important role in the development of science, namely in the development of atomic-molecular science. This discovery made it possible to obtain the most understandable and easy-to-learn ideas about simple and complex chemical compounds. It is only thanks to the table that we have the concepts about the elements that we use in the modern world. In the twentieth century, the predictive role of the periodic system in assessing the chemical properties of transuranium elements, shown by the creator of the table, emerged.
Developed in the 19th century, Mendeleev's periodic table in the interests of the science of chemistry provided a ready-made systematization of the types of atoms for the development of PHYSICS in the 20th century (physics of the atom and the atomic nucleus). At the beginning of the twentieth century, physicists, through research, established that the atomic number (also known as atomic number) is also a measure of the electrical charge of the atomic nucleus of this element. And the number of the period (i.e., horizontal series) determines the number of electron shells of the atom. It also turned out that the number of the vertical row of the table determines the quantum structure of the outer shell of the element (thus, elements of the same row are obliged to have similar chemical properties).
The discovery of the Russian scientist marked a new era in the history of world science; this discovery allowed not only to make a huge leap in chemistry, but was also invaluable for a number of other areas of science. The periodic table provided a coherent system of information about the elements, based on it, it became possible to draw scientific conclusions, and even anticipate some discoveries.
Periodic Table One of the features of the periodic table is that the group (column in the table) has more significant expressions of the periodic trend than for periods or blocks. Nowadays, the theory of quantum mechanics and atomic structure explains the group essence of elements by the fact that they have the same electronic configurations of valence shells, and as a result, elements that are located within the same column have very similar (identical) features of the electronic configuration, with similar chemical properties. There is also a clear tendency for a stable change in properties as the atomic mass increases. It should be noted that in some areas of the periodic table (for example, in blocks D and F), horizontal similarities are more noticeable than vertical ones.
The periodic table contains groups that are assigned serial numbers from 1 to 18 (from left to right), according to the international group naming system. In the past, Roman numerals were used to identify groups. In America, there was a practice of placing after the Roman numeral, the letter “A” when the group is located in blocks S and P, or the letter “B” for groups located in block D. The identifiers used at that time are the same as the latter the number of modern indexes in our time (for example, the name IVB corresponds to elements of group 4 in our time, and IVA is the 14th group of elements). In European countries of that time, a similar system was used, but here, the letter “A” referred to groups up to 10, and the letter “B” - after 10 inclusive. But groups 8,9,10 had ID VIII, as one triple group. These group names ceased to exist after the new IUPAC notation system, which is still used today, came into force in 1988.
Many groups received unsystematic names of a herbal nature (for example, “alkaline earth metals”, or “halogens”, and other similar names). Groups 3 to 14 did not receive such names, due to the fact that they are less similar to each other and have less compliance with vertical patterns; they are usually called either by number or by the name of the first element of the group (titanium, cobalt, etc.) .
Chemical elements belonging to the same group of the periodic table show certain trends in electronegativity, atomic radius and ionization energy. In one group, from top to bottom, the radius of the atom increases as the energy levels are filled, the valence electrons of the element move away from the nucleus, while the ionization energy decreases and the bonds in the atom weaken, which simplifies the removal of electrons. Electronegativity also decreases, this is a consequence of the fact that the distance between the nucleus and valence electrons increases. But there are also exceptions to these patterns, for example, electronegativity increases, instead of decreasing, in group 11, in the direction from top to bottom. There is a line in the periodic table called “Period”.
Among the groups, there are those in which horizontal directions are more significant (unlike others in which vertical directions are more important), such groups include block F, in which lanthanides and actinides form two important horizontal sequences.
Elements show certain patterns in atomic radius, electronegativity, ionization energy, and electron affinity energy. Due to the fact that for each subsequent element the number of charged particles increases, and electrons are attracted to the nucleus, the atomic radius decreases from left to right, along with this the ionization energy increases, and as the bond in the atom increases, the difficulty of removing an electron increases. Metals located on the left side of the table are characterized by a lower electron affinity energy indicator, and accordingly, on the right side the electron affinity energy indicator is higher for non-metals (not counting the noble gases).
Different regions of the periodic table, depending on which shell of the atom the last electron is located on, and in view of the importance of the electron shell, are usually described as blocks.
The S-block includes the first two groups of elements (alkali and alkaline earth metals, hydrogen and helium).
The P-block includes the last six groups, from 13 to 18 (according to IUPAC, or according to the system adopted in America - from IIIA to VIIIA), this block also includes all metalloids.
Block - D, groups 3 to 12 (IUPAC, or IIIB to IIB in American), this block includes all transition metals.
Block - F, is usually placed outside the periodic table, and includes lanthanides and actinides.
The periodic table is one of the greatest discoveries of mankind, which made it possible to organize knowledge about the world around us and discover new chemical elements. It is necessary for schoolchildren, as well as for anyone interested in chemistry. In addition, this scheme is indispensable in other areas of science.
This scheme contains all the elements known to man, and they are grouped depending on atomic mass and atomic number. These characteristics affect the properties of the elements. In total, there are 8 groups in the short version of the table; the elements included in one group have very similar properties. The first group contains hydrogen, lithium, potassium, copper, whose Latin pronunciation in Russian is cuprum. And also argentum - silver, cesium, gold - aurum and francium. The second group contains beryllium, magnesium, calcium, zinc, followed by strontium, cadmium, barium, and the group ends with mercury and radium.
The third group includes boron, aluminum, scandium, gallium, followed by yttrium, indium, lanthanum, and the group ends with thallium and actinium. The fourth group begins with carbon, silicon, titanium, continues with germanium, zirconium, tin and ends with hafnium, lead and rutherfordium. The fifth group contains elements such as nitrogen, phosphorus, vanadium, below are arsenic, niobium, antimony, then comes tantalum, bismuth and completes the group with dubnium. The sixth begins with oxygen, followed by sulfur, chromium, selenium, then molybdenum, tellurium, then tungsten, polonium and seaborgium.
In the seventh group, the first element is fluorine, followed by chlorine, manganese, bromine, technetium, followed by iodine, then rhenium, astatine and bohrium. The last group is the most numerous. It includes gases such as helium, neon, argon, krypton, xenon and radon. This group also includes metals iron, cobalt, nickel, rhodium, palladium, ruthenium, osmium, iridium, and platinum. Next come hannium and meitnerium. The elements that form the actinide series and lanthanide series. They have similar properties to lanthanum and actinium.
This scheme includes all types of elements, which are divided into 2 large groups - metals and non-metals, having different properties. How to determine whether an element belongs to one group or another will be helped by a conventional line that must be drawn from boron to astatine. It should be remembered that such a line can only be drawn in the full version of the table. All elements that are above this line and are located in the main subgroups are considered non-metals. And those below, in the main subgroups, are metals. Metals are also substances found in side subgroups. There are special pictures and photos in which you can familiarize yourself in detail with the position of these elements. It is worth noting that those elements that are on this line exhibit the same properties of both metals and non-metals.
A separate list is made up of amphoteric elements, which have dual properties and can form 2 types of compounds as a result of reactions. At the same time, they manifest both basic and acid properties. The predominance of certain properties depends on the reaction conditions and substances with which the amphoteric element reacts.
It is worth noting that this scheme, in its traditional design of good quality, is colored. At the same time, for ease of orientation, they are indicated in different colors. main and secondary subgroups. Elements are also grouped depending on the similarity of their properties.
However, nowadays, along with the color scheme, the black and white periodic table of Mendeleev is very common. This type is used for black and white printing. Despite its apparent complexity, working with it is just as convenient if you take into account some of the nuances. So, in this case, you can distinguish the main subgroup from the secondary one by differences in shades that are clearly visible. In addition, in the color version, elements with the presence of electrons on different layers are indicated different colors.
It is worth noting that in a single-color design it is not very difficult to navigate the scheme. For this purpose, the information indicated in each individual cell of the element will be sufficient.
The Unified State Exam today is the main type of test at the end of school, which means that special attention must be paid to preparing for it. Therefore, when choosing final exam in chemistry, you need to pay attention to materials that can help you pass it. As a rule, schoolchildren are allowed to use some tables during the exam, in particular, the periodic table in good quality. Therefore, in order for it to bring only benefits during testing, attention should be paid in advance to its structure and the study of the properties of the elements, as well as their sequence. You also need to learn use the black and white version of the table so as not to encounter some difficulties in the exam.
In addition to the main table characterizing the properties of elements and their dependence on atomic mass, there are other diagrams that can help in the study of chemistry. For example, there are tables of solubility and electronegativity of substances. The first can be used to determine how soluble a particular compound is in water at normal temperature. In this case, anions are located horizontally - negatively charged ions, and cations - that is, positively charged ions - are located vertically. To find out degree of solubility of one or another compound, it is necessary to find its components using the table. And at the place of their intersection there will be the necessary designation.
If it is the letter “p”, then the substance is completely soluble in water under normal conditions. If the letter “m” is present, the substance is slightly soluble, and if the letter “n” is present, it is almost insoluble. If there is a “+” sign, the compound does not form a precipitate and reacts with the solvent without residue. If a "-" sign is present, it means that such a substance does not exist. Sometimes you can also see the “?” sign in the table, then this means that the degree of solubility of this compound is not known for certain. Electronegativity of elements can vary from 1 to 8; there is also a special table to determine this parameter.
Another useful table is the metal activity series. All metals are located in it according to increasing degrees of electrochemical potential. The series of metal voltages begins with lithium and ends with gold. It is believed that the further to the left a metal occupies a place in a given row, the more active it is in chemical reactions. Thus, the most active metal Lithium is considered an alkaline metal. The list of elements also contains hydrogen towards the end. It is believed that the metals located after it are practically inactive. These include elements such as copper, mercury, silver, platinum and gold.
Periodic table pictures in good quality
This scheme is one of the largest achievements in the field of chemistry. Wherein there are many types of this table– short version, long, as well as extra-long. The most common is the short table, but the long version of the diagram is also common. It is worth noting that the short version of the circuit is not currently recommended for use by IUPAC.
In total there were More than a hundred types of tables have been developed, differing in presentation, form and graphical representation. They are used in different fields of science, or are not used at all. Currently, new circuit configurations continue to be developed by researchers. The main option is either a short or long circuit in excellent quality.
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.
- The metallic properties of elements decrease when moving along a period from left to right, and increase in the opposite direction.
- The sizes of atoms decrease when moving from left to right along periods.
- As you move from top to bottom through the group, the reducing metal properties increase.
- 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.
There are many repeating sequences in nature:
- Seasons;
- Times of Day;
- days of the week…
In the mid-19th century, D.I. Mendeleev noticed that the chemical properties of elements also have a certain sequence (they say that this idea came to him in a dream). The result of the scientist’s wonderful dreams was the Periodic Table of Chemical Elements, in which D.I. Mendeleev arranged chemical elements in order of increasing atomic mass. In the modern table, chemical elements are arranged in ascending order of the element's atomic number (the number of protons in the nucleus of an atom).
The atomic number is shown above the symbol of a chemical element, below the symbol is its atomic mass (the sum of protons and neutrons). Please note that the atomic mass of some elements is not a whole number! Remember isotopes! Atomic mass is the weighted average of all isotopes of an element found in nature under natural conditions.
Below the table are lanthanides and actinides.
Metals, non-metals, metalloids
Located in the Periodic Table to the left of a stepped diagonal line that begins with Boron (B) and ends with polonium (Po) (the exceptions are germanium (Ge) and antimony (Sb). It is easy to see that metals occupy most of the Periodic Table. Basic properties of metals : hard (except mercury); shiny; good electrical and thermal conductors; plastic; malleable; easily give up electrons.
The elements located to the right of the B-Po stepped diagonal are called non-metals. The properties of non-metals are exactly the opposite of those of metals: poor conductors of heat and electricity; fragile; non-malleable; non-plastic; usually accept electrons.
Metalloids
Between metals and non-metals there are semimetals(metalloids). They are characterized by the properties of both metals and non-metals. Semimetals have found their main application in industry in the production of semiconductors, without which not a single modern microcircuit or microprocessor is conceivable.
Periods and groups
As mentioned above, the periodic table consists of seven periods. In each period, the atomic numbers of elements increase from left to right.
The properties of elements change sequentially in periods: thus sodium (Na) and magnesium (Mg), located at the beginning of the third period, give up electrons (Na gives up one electron: 1s 2 2s 2 2p 6 3s 1 ; Mg gives up two electrons: 1s 2 2s 2 2p 6 3s 2). But chlorine (Cl), located at the end of the period, takes one element: 1s 2 2s 2 2p 6 3s 2 3p 5.
In groups, on the contrary, all elements have the same properties. For example, in group IA(1), all elements from lithium (Li) to francium (Fr) donate one electron. And all elements of group VIIA(17) take one element.
Some groups are so important that they have received special names. These groups are discussed below.
Group IA(1). Atoms of elements of this group have only one electron in their outer electron layer, so they easily give up one electron.
The most important alkali metals are sodium (Na) and potassium (K), since they play an important role in human life and are part of salts.
Electronic configurations:
- Li- 1s 2 2s 1 ;
- Na- 1s 2 2s 2 2p 6 3s 1 ;
- K- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1
Group IIA(2). Atoms of elements of this group have two electrons in their outer electron layer, which they also give up during chemical reactions. The most important element is calcium (Ca) - the basis of bones and teeth.
Electronic configurations:
- Be- 1s 2 2s 2 ;
- Mg- 1s 2 2s 2 2p 6 3s 2 ;
- Ca- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2
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 “complete 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- 1s 2 2s 2 2p 5 ;
- Cl- 1s 2 2s 2 2p 6 3s 2 3p 5 ;
- Br- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5
Group VIII(18). Atoms of elements of this group have a fully “complete” outer electron layer. Therefore, they “don’t” need to accept electrons. And they “don’t want” to give them away. Hence, the elements of this group are very “reluctant” to enter into chemical reactions. For a long time it was believed that they do not react at all (hence the name “inert”, i.e. “inactive”). But chemist Neil Bartlett discovered that some of these gases can still react with other elements under certain conditions.
Electronic configurations:
- Ne- 1s 2 2s 2 2p 6 ;
- Ar- 1s 2 2s 2 2p 6 3s 2 3p 6 ;
- Kr- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6
Valence elements in groups
It is easy to notice that within each group the elements are similar to each other in their valence electrons (electrons of s and p orbitals located on the outer energy level).
Alkali metals have 1 valence electron:
- Li- 1s 2 2s 1 ;
- Na- 1s 2 2s 2 2p 6 3s 1 ;
- K- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1
Alkaline earth metals have 2 valence electrons:
- Be- 1s 2 2s 2 ;
- Mg- 1s 2 2s 2 2p 6 3s 2 ;
- Ca- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2
Halogens have 7 valence electrons:
- F- 1s 2 2s 2 2p 5 ;
- Cl- 1s 2 2s 2 2p 6 3s 2 3p 5 ;
- Br- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5
Inert gases have 8 valence electrons:
- Ne- 1s 2 2s 2 2p 6 ;
- Ar- 1s 2 2s 2 2p 6 3s 2 3p 6 ;
- Kr- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6
For more information, see the article Valency and the Table of Electronic Configurations of Atoms of Chemical Elements by Period.
Let us now turn our attention to the elements located in groups with symbols IN. They are located in the center of the periodic table and are called transition metals.
A distinctive feature of these elements is the presence in the atoms of electrons that fill d-orbitals:
- Sc- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 1 ;
- Ti- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2
Separately from the main table are located lanthanides And actinides- these are the so-called internal transition metals. In the atoms of these elements, electrons fill f-orbitals:
- Ce- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 4d 10 5s 2 5p 6 4f 1 5d 1 6s 2 ;
- Th- 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 4d 10 5s 2 5p 6 4f 14 5d 10 6s 2 6p 6 6d 2 7s 2