Most of the elements that have been discovered over the past years have been identified at the nuclear research center in Dubna, Russia. At present, the periodic system looks completely unusual, but the search for new elements continues.
There are many myths around the name of Dmitry Ivanovich Mendeleev. For example, that he made an important contribution to the production of vodka with his doctoral dissertation on the relationship between alcohol and water, which a Russian chemist defended in 1865 at the Technological Institute in St. Petersburg. Or that the brilliant idea to put things in order in the then chaos of chemical elements came to him in a dream in 1869. However, both of these curious stories lack reliable evidence.
It is known for sure that 148 years ago, on October 28, 1869, he published the periodic table of chemical elements, which finally ordered the 63 elements known then, by placing them in the form of a table in ascending order of the number of protons.
With this, Mendeleev also put an end to the 50-year search for the relationship between the mass of atoms and the properties of elements: in his periodic system, roughly speaking, alkali metals are grouped on the left, inert gases - on the right, between them are transition metals, non-metals and other series.
Rare completeness
But, despite its fundamental importance, the periodic table is still not final. It follows from this that along with the 118 elements known to us today, there are many others. They are being searched for in a small Russian town on the Volga, about 120 kilometers north of Moscow, called Dubna.
At this time of the year, the city is adorned with variegated tree leaves that tower over small, single-family houses. Until you enter the territory of the Joint Institute for Nuclear Research (JINR) hidden behind a high fence, it is difficult to assume that you are in a scientific city of world significance.
Promotional video:
Where forests and thickets still reigned a few decades ago, a center for elementary particle physics was opened in 1956. Of the 18 elements that have since been discovered around the world, ten have been discovered at this institute.
So Dubna contributed to the fact that all the lines of the periodic table are currently filled: at the beginning of 2016, four new elements in the periodic table were officially recognized, due to which its seventh row was completed. In November last year, they finally got their official names: element with serial number 113 was given the name Nihonium (Nh) in honor of Japan (Japanese Nihon), number 115 - Muscovy (M) in honor of Moscow, number 117 - Tennessin (Ts) in honor of the American state of Tennessee, and number 118 - oganesson (Og) in honor of his co-founder and head of the laboratory of nuclear reactions at JINR in Dubna, Yuri Oganesyan.
With 118 protons, oganesson is currently the element with the highest atomic number. The synthesis of heavy atomic nuclei of this type at JINR occurs through particle collisions. The oganesson element was obtained by colliding the nuclei of the calcium isotope Ca-48 with the radioactive metal Californium Cf-249.
Ultimate accuracy
As Andrei Popako, a JINR researcher, emphasizes, in this case, an extremely accurately calculated energy value should be used: if the energy is not enough, then the atomic nuclei, although they will approach, will fly apart from each other. If there is too much energy in the collision, new fragments will appear, but not new atomic nuclei. “To create new atoms, the accuracy of setting the ion energy must not exceed one percent,” says Popako. But no particularly high energies are required, "for this reason we do not need such a large hadron collider like CERN."
The rate of production of superheavy elements is correspondingly limited: currently, one oganesson atom is generated per month. This is not only about fundamental research, the elements also have a commercial price. The radioactive element Californium Cf-252 sells for about $ 27 million (approximately € 23 million) per gram. It is used, for example, in the oil industry to analyze the porosity and permeability of oil-bearing formations.
To penetrate the eighth row of the periodic table, the researchers under the leadership of Popako plan to start with titanium, but it still behaves chemically extremely aggressively in the accelerator. Researchers may have to look for other starting material for the synthesis of new elements.
Alexander Vladimirovich Karpov, a leading researcher at the theoretical department of the Laboratory of Nuclear Reactions at JINR, believes that the eighth period in the system will never be filled, we are talking about more than 50 elements, of which none have yet been discovered. His advice: "Use the periodic table while it is filled as it is now."
Tanja Traxler