Everyone who attended school remembers that one of the mandatory subjects was chemistry. Whether you liked it or not was not important in this case. It is quite possible that most of the knowledge in this discipline will be forgotten and no longer used on a daily basis.
However, D. I. Mendeleev's periodic table of elements will surely be remembered by all. For many, it is still a table of colors, each cell contains letters that denote the names of the elements chemicals.
Some history of the periodic table
A long time ago, in 1668, a leading Irish chemist, physicist, and theologian, Robert Boyle, published a book in which he debunked many myths about the alchemy In it, he addressed the need to search for indivisible chemical elements.
The scientist attached a list of only 15 items, but assumed a larger number. The book became the starting point for the search for new elements and their systematization.
One hundred years later, the French chemist Antoine Lavoisier compiled a new list that already included 35 elements. 23 of them were later declared indivisible. Many scientists around the world continued to search for new elements.
The famous Russian chemist Dmitri Ivanovich Mendeleev played an important role in this process: he was the first to hypothesize that there may be a mutual relationship between the atomic mass of the elements
Thanks to the juxtaposition of elements chemicals, Mendeleev was able to find a connection between elements that can constitute a whole, and their properties do not understand themselves, but constitute a phenomenon that repeats itself periodically.
As a result, in February 1869, Mendeleev formulated the first law of periodicity; in March, his article "Correlation of properties with the atomic mass of elements" was presented to the Society of Chemists of Russia under the chairmanship of Nikolai Menshutkin. p>
In the same year, the publication of Mendeleev took place in the magazine "Zeitschrift fur Chemie" in Germany, and in 1871 a new complete publication of the scientist, dedicated to his invention, was published by another German magazine, "Annalen der Chemie".
Creation of the periodic table of elements
In 1969 Mendeleev formulated the basic idea. He did it in a very short time, but for a long time he could not form a uniform and orderly system, showing tangible logical connections. P>
In one of the conversations with his colleague A. A. Inostrancewy, even said that he had everything in his head, but that he couldn't bring it to the form of a blackboard . P>
After that, according to one of Mendeleev's biographers, the scientist began to work for three days without sleeping breaks.
he went through all the ways to organize the elements, but the process was complicated by the fact that the science of that time did not know many of them. Regardless of this, the elements were systematized.
Organization of the periodic table of elements
The chemical elements in Mendeleev's table are placed in the sequences according to their increase in mass, and the lengths of the rows are adjusted so that the elements in them have similar properties.
For example, noble gases such as radon, xenon, krypton, argon, neon, and helium react poorly to other elements and have low chemical activity, so they are placed in the last column.
On the other hand, the elements in the left column (potassium, sodium, lithium, etc) react very well with the rest of the elements, and these reactions are explosive .
All elements up to number 92 are found in nature. Artificial elements that can only be obtained under laboratory conditions start with the number 93.
In its original version, the periodic table was understood as a reflection of an existing order in nature, without any explanation of why it was supposed to be so.
Only after the advent of quantum mechanics became clear the real meaning of the order of the elements.
The Modern Periodic Table
The periodic table has remained essentially unchanged for almost a hundred years. Of course, from time to time it is complemented with new elements obtained in scientific laboratories.
Its shape has also changed a bit, as lanthanide and actinide groups have been separated from it. However, there are no vacancies inside, they have all been filled.
The last element inside the periodic table was technetium (Tc) predicted by Mendeleev in 1871, discovered in 1936 by Italian scientists under the supervision of Emilio Segrè.
Various forms of the periodic table are created around the world. We will find its round, spiral, helical, looped, pyramidal figures... However, the basic principle of creation of the periodic table remains unshakeable.
Lessons from the creative process
Speaking of this topic, we can cite as an example the ideas of the English researcher on the scope of creative thinking Graham Wallas and the French scientist Henri Poincaré.
According to research by Poincaré (1908) and Graham Wallas (1926), there are four basic stages of creative thinking:
- Preparation: the stage of formulating a basic task and the first attempts to solve it.
- Incubation: A stage during which a temporary distraction from the process takes place, but work to find a solution is still ongoing, albeit at a subconscious level.
- Enlightenment: the stage where intuitive thinking enters. It can be experienced in a completely non-task situation.
- Verification: the stage of testing and implementing the solution, during which verification and possible further development take place.
As you can see, Mendeleev intuitively adhered to these four stages in the process of creating his periodic table. To the extent that it is effective, we can infer the results.
And since the board has become a great step forward not only for chemistry but for all of humanity, the above four steps can be used in small projects, like so to make global ideas come true.
It is important to remember that no inventions or solutions will come to you. It doesn't matter how much we want to see them in a dream.
For something to work, whether it's creating a periodic table or developing a new marketing plan, you need to have certain knowledge and skills and consciously use your potential, working hard.< /p>
Structure of the modern periodic table of elements
The modern periodic table consists of vertical columns, called groups, and horizontal series, called periods. Each period begins with a highly reactive metal and ends with a nonmetal.
The periodic table contains seven periods, numbered with Arabic numerals.The latest recommendations require that the groups be numbered consecutively with Arabic numerals from 1 to 18
This method avoids the use of the letters A and B, which until now have been used inconsistently.
The name of the group is derived from the name of the element that is at the beginning of the group (the first group takes its name from lithium, not hydrogen and is called alkali metals, the second group from beryllium etc .).
All elements in the periodic table have their symbols next to which are the atomic number and atomic weight.
An atomic number, sometimes called an ordinal number, determines the number of protons in the nucleus of an atom of a element and determines the position of the element in the periodic table.
If we analyze the position of the elements in the periodic table, we can very easily confirm the validity of the law of periodicity, which speaks of periodically repeating properties of the elements arranged according to increasing atomic numbers.
Physical and chemicals quantities that change periodically depending on the position of the element in the system include: ionic and atomic rays, boiling and melting point, density, electronegativity, energy of ionization, electronic affinity, degree of oxidation, etc.
The periodicity of the properties of elements is also reflected in the properties of chemical compounds. The elements belonging to a periodic table group have similar chemical and physical properties.
The lithium group (the first of the periodic table) are metals, they form strong hydroxides and become stronger the closer to the bottom left of the periodic table there is the element . The reactivity of the described metals also increases in the same direction.
Lithium metals and their combinations with hydrogen (alkali metal hydrides) are strong reducing agents, and their reducing properties are stronger the greater the atomic mass of the alkali metal.
Similarly (bottom left of periodic table) the electronegativity value decreases and the atomic radius increases. The halogens are the seventeenth group in the periodic table.
They are non-metals that form acids. All halogen acids, both aerobic and anaerobic, are strong acids. The strongest acids are those that make up the elements found in the upper right corner of the periodic table.
The chemical reactivity of the elements in the seventeenth group of the periodic table increases towards the upper right of the periodic table , in the same direction increases electronegativity and non-metallicity.
The elements of the periodic table can be divided into:
They have good thermal and electrical conductivity. Metals have a characteristic shine and are usually malleable. They tend to have low electronegativity and in chemicals reactions they tend to donate their electrons and form positive ions.
At room temperature, all metals are solids (except mercury) and form metallic crystals. Of the 111 elements known, 88 are metals.
Depending on density, metals can be divided into heavy and light metals. They are widespread in nature, where they are most often found in the form of minerals.
They are elements chemicals that have intermediate properties between metals and non-metals. They have semiconducting properties and include: tellurium, selenium, antimony, germanium, silicon, arsenic, and boron.
These are elements chemicals that show poor electrical conductivity (they are generally semiconductors or insulators) and generally poor thermal conductivity (the exception is the allotropic form of carbon: diamond ).