Inorganic chemistry

Periodic table of chemistry?

Periodic table of chemistry?


Is the periodic table of elements finished :

The periodic table established by Dmitri Mendeleev in 1869, then counted 63 elements. Today, there are 118. Some are said to be primordial, because older than our Earth, others were synthesized by Man. So, should we expect to see it grow even bigger?

The uranium is the heaviest element found in nature. The periodic table could therefore stop at this atomic number element  92. Yet, on closer examination, we discover that Mendeleev’s painting has many other elements. Of artificial elements that the physicists have created in the laboratory. In accelerators, more exactly.

How? ‘Or’ What ? By propelling a beam of atoms that are usually quite light on a target of heavier atoms. For when sometimes light atoms and heavy atoms collide and merge, a whole new element is born . Thus, by sending neon – of atomic number 10 – on uranium – of atomic number 92 -, the researchers can obtain nobelium – of atomic number 102.

Note that some atom combinations have extremely low merging probabilities. Blame their respective chemical and physical properties . It remains difficult for physicists to make new elements. Moreover, they do not detect them, most of the time, only when they have already disappeared. They are then betrayed only by the results of their disintegration.


The end of the periodic table with the atomic number 172?

One theory is that beyond 172 protons – beyond the atomic number 172 – strange quantum phenomena occur around the nucleus of an atom. As the formation of electron-positron pairs preventing the establishment of an electronic procession and therefore an atom in the strict sense of the term. Thus, the atomic number 172 could mark the end of the periodic table. But many scientists believe that long before this limit, the concentration of protons in the atomic nucleus becomes so great that the nucleus disintegrates almost instantaneously.

In 2019, the heavier item ever produced is item 118, the oganesson . And it becomes extremely difficult to go beyond. For this, it would require several milligrams of the target element. Now, for the time being, technology does not allow physicists to produce, for example, enough einsteinium – of atomic number 99 – to make element 119 – which would come, together with element 120, to constitute a 8 th row of the periodic table.

Moreover, beyond the atomic number 120, the lifetime of an atom becomes so low that it becomes almost impossible to detect its existence. Except perhaps for those who would be in the island of stability. Counting a  “  magic number  ” of protons and neutrons , they would appear surprisingly stable compared to their neighbors in the periodic table.

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