150th anniversary of the periodic table of chemical elements

The periodic table of chemical elements, or, is a method of listing chemical elements into tables, based on atomic numbers (number of protons in the nucleus), electron configuration and cyclic chemical properties. of them. Elements are represented in the order of increasing number of atomic numbers, often listed along with chemical symbols in each cell.

The standard form of the table consists of elements arranged in 18 columns and 7 lines, with two separate dual lines located on the bottom. Although there were pioneers before, Dmitri Ivanovich Mendeleev (1834 - 1907) was often considered to be the first to publish the periodic table in 1869.

Mendeleev developed his periodic table to illustrate circulatory trends in the properties of known elements at the time. Mendeleev also predicts some of the properties of unknown elements that he hopes will fill in the blanks in this table. Most of his predictions were accurate when the elements were in turn discovered.

Dmitri Ivanovich Mendeleev (photo printed on the periodic table of Russian chemical elements), has just been celebrated by UNESCO for 150 years.

Mendeleev's periodic table has since been expanded and modified with the discovery or synthesis of new elements and the development of theoretical models to explain chemical properties. And since then, 55 elements have been added, including 24 created by humans.

To date, Mendeleev's periodic table of chemical elements is 150 years old, and UNESCO chose January 29, 2019 as the "Year of Chemical Elements" to honor the meritorious and commemorative. this event.

And among the guests attending the celebration, there was Yuri Oganessian , Scientific Director of the Flerov Nuclear Reaction Laboratory in Dubna (Russia).

It was on this occasion that Yuri Oganessian discussed the challenges of creating super-heavy nuclei. So what did this Russian physicist bring to science?

For a long time, while studying Mendeleev's periodic table, Yuri Oganessian reclassified 63 elements according to their mass to properly align the correct column and found that all elements of a column were Similar chemical properties.

The photo of Yuri Oganessian on the stamp was released by Russia to honor him.

With the proton (discovered in 1913) and then the neutron (1932), he understood that it was an atomic number, the number of protons contained in the nucleus and not the mass to distinguish the elements, but this did not change Mendeleev's periodic table.

But that means that this scientist was about half a century ahead of his time!

In 2015, the table of these elements was completed, in which 14 artificial elements called 'superheavy' were added as oganesson (atomic number 118).

In nature, the heaviest elements are forged in the explosion of end-of-life stars, known as supernovae, which are hot to several billion degrees. But these are disasters that we cannot replicate in the lab.

Therefore, it is only possible to experiment with highly accelerating particles, which require a huge amount of energy because all cores are positively charged. This creates an extremely strong repulsion between them, called "Coulomb fences".

Overcoming this barrier for a strong interaction force (the force acting at the nuclear level) can integrate a nucleus of the beam with another target to create a heavier element.