In the periodic table there are 118 elements , of which 30 can be bought in stores, such as helium or iron. Another 12 can be obtained by disassembling everyday objects, such as a small sample of americium in a smoke detector.
At the bottom of the periodic table are a large number of rare elements called transuranic elements . For a long time, many of them had reference names such as aununio, although little by little they have been assigned definitive names.
Most of these elements do not exist permanently and are generated in particle accelerators. Many last only a few minutes before disappearing. For example, if we have 100,000 livermorio atoms (element 116), after one second we would only have 1 atom left . And later, nothing.
4 new findings
That is why it is possible that, as recently as 2014, the existence of a new element in the periodic table was officially confirmed. It was baptized as ununseptium and has thus become the element number 117. It is also the second heaviest element in the world, 40% more than lead.

Ununseptium has been synthesized by a group of physicists at the German GSI research center on heavy ions in Darmstadt, using a linear accelerator. Although in 2010 it had already been synthesized by Russian and North American researchers from the University of Dubna, near Moscow, to be recognized and incorporated into the periodic table the International Union of Pure and Applied Chemistry (IUPAC) requires that the new element is synthesized, at least, in two independent laboratories .
To synthesize, on this last occasion, ununseptium nuclei of calcium-48 were collided with berkelium-249. When both nuclei merge, element 117 is obtained. It is found in the penultimate column of the periodic table, along with halogens (fluorine, chlorine, bromine, iodine and astate).
Then came element number 118, ununoctium , also called eka-radon. In 1999, researchers from the Lawrece Berkeley laboratory believed they had found it. Later, Japanese and German researchers failed to replicate the experiment, and one of the 15 Berkeley scientists involved in the project had to admit that the initial data had been made up. So ununoctium was first detected (this time for real) in 2002, but the second time, in 2006, it is not entirely convincing to the IUPAC, so it has not yet been incorporated into the periodic table .
The reason the element is so elusive is that it is very radioactive and unstable. Ununoctium is in the same column as the noble gases (helium, neon, argon, krypton, xenon, and radon), but it is not yet known if it is a noble gas: it may be a solid under normal pressure and temperature conditions. The most interesting thing is that ununoctium is even heavier than copernicium.
Finally, on December 30, 2015, the IUPAC announced the verification of oganeson. The new element was thus called in Spanish (with the ending -on tonic) following the orthographic criteria for the naming of noble gases (neon, xenon …). It was named in honor of the Russian physicist, Yuri Oganesián .
In total, then, we have several new but ephemeral elements: element 113, also known as "ununtrium", which, together with 115 ("ununpentium"), 117 ("ununseptium") and 118 ("ununoctium"), make up the four elements discovered in previous years and incorporated into the periodic table as of December 30, 2015.
The 113 would be renamed Nihonium , which means "the land of the rising sun", and would have the symbol (Nh). The 115 would be called Muscovio (Mc) and 117, Tenesina (Ts). Finally, element 118, as already mentioned, is called oganeson (Og).