If the periodic table seems difficult for you to understand, you are not alone! Although it can be difficult to understand its principles, learning to work with it will help in the study of 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
Table structure- 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.
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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".
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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.
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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".
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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-
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.
- Typically, element symbols are shorthand for their Latin name, although for some, especially recently discovered 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.
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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.
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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.
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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!
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The periodic table, or periodic table of chemical elements, begins at the top left and ends at the end of the last line 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.
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.
The Periodic Table of the Elements had a great influence on the subsequent development of chemistry.
Dmitry Ivanovich Mendeleev (1834-1907)
Not only was it the first natural classification of the chemical elements, which showed that they form a coherent system and are in close connection with each other, but it was also a powerful tool for further research.
At the time when Mendeleev compiled his table on the basis of the periodic law he discovered, many elements were still unknown. So, the element of the fourth period, scandium, was unknown. In terms of atomic weight, titanium followed calcium, but titanium could not be placed immediately after calcium, since it would fall into the third group, while titanium forms the highest oxide, and, according to other properties, should be assigned to the fourth group. Therefore, Mendeleev skipped one cell, i.e., left a free space between calcium and titanium. On the same basis, in the fourth period, two free cells were left between zinc and arsenic, now occupied by the elements gallium and germanium. There were also empty seats in other rows. Mendeleev was not only convinced that there must be elements yet unknown to fill these places, but he also predicted the properties of such elements in advance, based on their position among other elements of the periodic system. One of them, which in the future was to take a place between calcium and titanium, he gave the name ekabor (since its properties were supposed to resemble boron); the other two, for which there were empty places in the table between zinc and arsenic, were called eka-aluminum and ekasilicium.
Over the next 15 years, Mendeleev's predictions were brilliantly confirmed: all three expected elements were discovered. First, the French chemist Lecoq de Boisbaudran discovered gallium, which has all the properties of ekaaluminum; after that, scandium, which had the properties of ecabor, was discovered in Sweden by L. F. Nilson, and, finally, a few more years later, in Germany, K. A. Winkler discovered an element that he called germanium, which turned out to be identical to ecasilium.
To judge the amazing accuracy of Mendeleev's prediction, let's compare the properties of ecasilicon predicted by him in 1871 with the properties of germanium discovered in 1886:
The discovery of gallium, scandium and germanium was the greatest triumph of the periodic law.
The periodic system was also of great importance in establishing the valency and atomic masses of certain elements. Thus, the element beryllium has long been considered an analogue of aluminum, and its oxide was assigned the formula . Based on the percentage composition and the proposed formula of beryllium oxide, its atomic mass was considered equal to 13.5. The periodic system showed that there is only one place for beryllium in the table, namely, above magnesium, so its oxide must have the formula , whence the atomic mass of beryllium is equal to ten. This conclusion was soon confirmed by the determination of the atomic mass of beryllium from the vapor density of its chloride.
Exactly And today the periodic law remains the guiding thread and the guiding principle of chemistry. It is on its basis that transuranium elements have been artificially created in recent decades, located in the periodic system after uranium. One of them - element No. 101, first obtained in 1955 - was named mendelevium in honor of the great Russian scientist.
The discovery of the periodic law and the creation of a system of chemical elements was of great importance not only for chemistry, but also for philosophy, for our entire understanding of the world. Mendeleev showed that the chemical elements constitute a coherent system, which is based on the fundamental law of nature. This is the expression of the position of materialist dialectics on the interconnection and interdependence of natural phenomena. Revealing the relationship between the properties of chemical elements and the mass of their atoms, the periodic law was a brilliant confirmation of one of the universal laws of the development of nature - the law of the transition of quantity into quality.
The subsequent development of science made it possible, relying on the periodic law, to know the structure of matter much more deeply than was possible during the life of Mendeleev.
The theory of the structure of the atom developed in the 20th century, in turn, gave the periodic law and the periodic system of elements a new, deeper illumination. Brilliant confirmation was found by Mendeleev's prophetic words: "The periodic law is not threatened with destruction, but only a superstructure and development are promised."
The Periodic Table of Elements was the first natural classification of chemical elements, showing that they are interconnected with each other, and also served as further research.
When Mendeleev compiled his table on the basis of the periodic law he discovered, many elements were still unknown. Like, for example, the three elements of the 4th period. Presumably, the elements were called ekabor (its properties should resemble boron), ekaaluminum, ekasilicium. Within 15 years, Mendeleev's predictions were confirmed. French chemist Lecoq de Boisbaudran discovered gallium, which has all the properties of ekaaluminum, L.F. Nilson discovered scandium, and K.A. Winkler discovered the element germanium, which has the properties of ecasilicon.
The discovery of Ga, Sc, Ge is proof of the existence of the periodic law. The periodic system was also of great importance in establishing the valency and atomic masses of certain elements, correcting some of them. Based on the periodic law, transuranium elements have now been created.
End of work -
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Receipt
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Mineral fertilizers
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Learning new material .
Dmitri Ivanovich Mendeleev- a brilliant Russian scientist who managed to create a strictly scientific classification of chem. elements, which is the Periodic system. It contains all the chemical elements known to science, the entire diversity of the surrounding world is built from elements, the elements in this table are usually denoted by chemical signs or symbols. In order to use the table, you need to know the "chemical language" or "chemical alphabet". There are 33 letters in the Russian alphabet, and 109 in the chemical alphabet.
In this post, you will learn how to correctly designate chemical elements.
Signs of chemical elements.
So, in your opinion, it is easiest to write a chemical phenomenon with signs, but which ones?
The exact same problem arose before the chemists of the Middle Ages.
At that time, scientists, they were called, as you remember, alchemists, knew 10 chemical elements - seven metals (gold, silver, copper, iron, tin, lead and mercury) and three non-metals (sulphur, carbon and antimony).
The alchemists believed that the chemical elements were associated with the stars and planets and assigned astrological symbols to them.
Gold was called the Sun, and was indicated by a circle with a dot.Copper - Venus, the symbol of this metal was the "Venus mirror". Alchemists did without chemical formulas for a very long time. There were strange signs in use, and almost every chemist used his own system of notation for substances. It was very inconvenient. There was a real confusion: the same chemical reactions were written in different signs. It was necessary to introduce a unified system of notation.
In the 18th century, a system of designation of elements (of which three dozen had already become known at that time) took root in the form of geometric figures - circles, semicircles, triangles, squares.
The symbols for chemical elements currently in use were introduced by the Swedish chemist Jens Jakob Berzelius.
Each element has its own symbol, understandable to scientists of any country. The first, capital, letter of the symbol is always the first letter of the element's full Latin name. If the names of several elements begin with such a letter, then one more letter is added to the first letter.
For example: Oxygen - Oxуgenium - O
Carbon - Сarboneum - C
Calcium - Calcium - Ca
Characters are pronounced according to the letter of the Latin alphabet.
For example: oxygen - O - "o"
nitrogen - N - "en"
Others are read in Russian.
For example: calcium - Ca - "calcium"
Sodium - Na - "sodium"
You don't need to memorize all the elements. But for our further work, a number of elements must be learned.
All of them are recorded in the textbook on page 35. All elements can be conditionally divided into metals and non-metals.
Etymology of the names of chemical elements:
Consider the etymology of the names of chemical elements, i.e. the origin of their names.
The name reflects the most important property of a simple substance formed by this element: hydrogen - "giving birth to water", phosphorus - "carrying light"
Myths of the ancient Greeks: promethium - prometheus, tantalum - tantalum
- geographical names
Geographical names: states - gallium, germanium, polonium, ruthenium; cities - lutetium (Paris), hafnium (Copenhagen).
- astronomical names
Astronomy: selenium - moon, tellurium - earth, uranium, neptunium
- names of scientists
Names of great scientists: fermium, curium, einsteinium, mendelevium
The structure of the Periodic system of chemical elements of D.I. Mendeleev
Now we will consider with you, perhaps, the most important document, a “hint” for any chemist. Open the flyleaf of your textbook, and also use the tables that are on your desks. Before you is the table "Periodic system of Dmitry Ivanovich Mendeleev." As you can see, they are somewhat different, but not significantly. The periodic system is the Big House of Chemical Elements, which was built in 1869 by D. I. Mendeleev.
GROUPS, each of which consists of the main (elements on the left) and secondary (elements on the right) subgroups. Each element has its own separate “apartment” with a serial number.Some "entrances" - groups , have a common name reflecting their common properties: alkali metals, halogens, noble or inert gases .
In addition, separately below, in the "basement" are lanthanides and actinides, which are very similar to lanthanum, and others to actinium.
The table also reflects the belonging of the element to a certain group: metal, non-metal or transition element.
The Periodic Table of the Elements had a great influence on the subsequent development of chemistry. Not only was it the first natural classification of the chemical elements, which showed that they form a coherent system and are in close connection with each other, but it was also a powerful tool for further research.
At the time when Mendeleev compiled his table on the basis of the periodic law he had discovered, many elements were still unknown. So, for example, the element located in the fourth row was unknown. In terms of atomic weight, it followed calcium, but it could not be placed immediately after calcium, since it would fall into the third group, while tetravalent forms the highest oxide TiO 2, and for all other properties it should be assigned to the fourth group. Therefore, Mendeleev skipped one cell, i.e., left a free space between calcium and titanium. On the same basis, in the fifth row, between zinc and arsenic, two free cells were left, now occupied by the elements thallium and germanium. There were also empty seats in other rows. Mendeleev was not only convinced that there must be still unknown elements that would fill these places, but also in advancepredicted the properties of such elements based on their position among other elements in the periodic table.
One of them, which in the future was to take a place between calcium and titanium, he gave the name eka-boron (since its properties were supposed to resemble boron); the other two, for which there were empty places in the table in the fifth row between zinc and arsenic, were called eka-aluminum and eka-silicon.
Predicting the properties of these unknown elements, Mendeleev wrote: “I decide to do this so that, although in time, when one of these predicted bodies is discovered, I will be able to finally convince myself and > convince other chemists of the validity of those assumptions that underlie the proposed system by me."
Over the next 15 years, Mendeleev's predictions were brilliantly confirmed: all three expected elements were indeed discovered. First, the French chemist Lecoq de Boisbaudran discovered a new element that has all the properties of eca-aluminum; after that, Nilson discovered in Sweden, which had the properties of eka-boron, and, finally, a few more years later in Germany, Winkler discovered an element that he called germanium, which turned out to be identical with eka-silicium.
To judge the amazing accuracy of Mendeleev's predictions, let's compare the properties of eca-silicon predicted by him in 1871 with the properties of germanium discovered in 1886:
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eca-silicon properties Eka-silicon Es is a fusible metal capable of volatilizing in extreme heat The atomic weight of Es is close to 72 Specific gravity Es approx. 5.5 EsO 2 should be easy to recover The specific gravity of EsO 2 will be close to 4.7 EvCl 4 - a liquid boiling at about 90 °, its specific gravity is close to 1.9 |
germanium properties Atomic weight Ge 72.6 Specific gravity Ge 5.35 at 20° GeO 2 is easily reduced by coal or hydrogen to metal Specific gravity of GeO 2 4.703 at 18° GeCl 4 - liquid boiling at 83 °, its specific gravity is 1.88 at 18 ° |
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The discovery of gallium, scandium and germanium was the greatest triumph of the periodic law. The whole world started talking about the theoretical predictions of the Russian chemist that had come true and about his periodic law, which after that received universal recognition.
Mendeleev himself greeted these discoveries with deep satisfaction. “While writing in 1871 an article on the application of periodic law to determine the properties of elements not yet discovered, - he said, - I did not think that I would live to justify this consequence of the periodic law, but reality answered differently. Three elements were described by me: ekabor, ekaaluminum and ekasilicium, and less than 20 years had passed, as I already had the greatest joy to see all three open ... ".
The periodic system was also of great importance in solving the problem of the valency and atomic weights of certain elements. So, for example, the element was considered for a long time an analogue of aluminum, and its oxide was assigned the formula Be 2 O 3. By analysis, it was found that in beryllium oxide, 16 weight parts of oxygen account for 9 weight. including beryllium. But since the volatile compounds of beryllium were not known, it was not possible to determine the exact atomic weight of this element. Based on the percentage composition and the proposed formula of beryllium oxide, its atomic weight was considered equal to 13.5. The periodic table showed that there is only one place for beryllium in the table, namely above magnesium, so that its oxide must have the formula BeO, whence the atomic weight of beryllium is nine. This conclusion was soon confirmed by determinations of the vapor density of beryllium chloride, which made it possible to calculate the atomic weight of beryllium.
Similarly, the periodic table gave impetus to the correction of the atomic weights of certain rare elements. For example, cesium was previously assigned an atomic weight of 123.4. Mendeleev, arranging the elements in a table, found that, according to its properties, cesium should be in the left column of the first group under rubidium and therefore will have an atomic weight of about 130. The latest definitions show that the atomic weight of cesium is 132.91.
Initially, he was met very coldly and incredulously. When Mendeleev, relying on his discovery, called into question a number of experimental data on atomic weights and decided to predict the existence and properties of elements not yet discovered, many chemists reacted to his bold statements with undisguised disdain. So, for example, L. Meyer wrote in 1870 about the periodic law: "It would be hasty to change the hitherto accepted atomic weights on such shaky grounds."
However, after Mendeleev's predictions were confirmed and received general recognition, attempts were made in a number of countries to challenge Mendeleev's primacy and attribute the discovery of the periodic law to other scientists.
Protesting against such attempts, Mendeleev wrote: “The approval of a law is possible only with the help of deriving consequences from it, without which it is impossible and not expected, and justifying those consequences in experimental verification. That is why, having seen, I, for my part (1869-1871), deduced from it such logical consequences that could show whether it was true or not. Without such a method of testing, no law of nature can be established. Neither Chancourtois, to whom the French attribute the right to discover the periodic law, nor Newlands, whom the British put forward, nor L. Meyer, whom others have quoted as the founder of the periodic law, dared to predict properties of undiscovered elements, to change the "accepted weights of atoms" and in general to consider the periodic law as a new, strictly established law of nature, capable of covering hitherto ungeneralized facts, as I did from the very beginning (1869).
The discovery of the periodic law and the creation of a system of chemical elements was of great importance not only for chemistry and other natural sciences, but also for philosophy, for our entire understanding of the world. Revealing the relationship between the properties of chemical elements and the quantity in their atoms, the periodic law was a brilliant confirmation of the universal law of the development of nature, the law of the transition of quantity into quality.
Before Mendeleev, chemists grouped elements according to their chemical similarity, seeking to bring together only similar elements. Mendeleev approached the consideration of elements in a completely different way. He embarked on the path of convergence of dissimilar elements, placing next to him chemically different elements that had close values of atomic weights. It was this comparison that made it possible to reveal a deep organic connection between all elements and led to the discovery of the periodic law.
