Scientists Complete the Periodic Table

Elements 113, 115, 117, and 118 Are Official Discovered

Row 7 is the final row of elements in the periodic table. Scientists have verified the discovery of the last four elements.
Row 7 is the final row of elements in the periodic table. Scientists have verified the discovery of the last four elements. Todd Helmenstine, sciencenotes.org

 The periodic table as we know it is now complete! The International Union of Pure and Applied Chemistry (IUPAC) has announced verification of the only elements left -- elements 113, 115, 117, and 118. These elements complete the 7th and final row of the periodic table of elements. Of course, if elements with higher atomic numbers are discovered, then an additional row will be added to the table.

Details on the Discoveries of the Last Four Elements

The fourth IUPAC/IUPAP Joint Working Party (JWP) reviewed literature to determine claims for verification of these last few elements have fulfilled all the criteria necessary to "officially" discover the elements.

What this means is the discovery of the elements has been replicated and demonstrated to the satisfaction of scientists according to the 1991 discovery criteria decided by the IUPAP/IUPAC Transfermium Working Group (TWG). The discoveries are credited to Japan, Russia, and the USA. These groups will be allowed to propose the names and symbols for the elements, which will need to be approved before the elements take their place on the periodic table.

Element 113 Discovery

Element 113 has the temporary working name ununtrium, with symbol Uut. The RIKEN team in Japan has been credited with discovering this element. Many people hope Japan will choose a name like "japonium" for this element, with symbol J or Jp, since J is the one letter presently absent from the periodic table.

Elements 115, 117, and 118 Discovery

Elements 115 (ununpentium, Uup) and 117 (ununseptium, Uus) were discovered by a collaboration between Oak Ridge National Laboratory in Oak Ridge, TN, Lawrence Livermore National Laboratory in California, and the Joint Institute for Nuclear Research in Dubna, Russia.

Researchers from these groups will propose new names and symbols for these elements.

Element 118 (ununoctium, Uuo) discovery is credited to a collaboration between the Joint Institute for Nuclear Research in Dubna, Russia and Lawrence Livermore National Laboratory in California. This group has discovered several elements, so they're sure to have a challenge ahead of them coming up with new names and symbols.

Why It's So Hard To Discover New Elements

While scientists may be able to make new elements, it's difficult to prove the discovery because these superheavy nuclei decay into lighter elements instantaneously. Proof of the elements requires demonstration that the set of daughter nuclei that are observed can be unequivocally attributed to the heavy, new element. It would be much simpler if it was possible to directly detect and measure the new element, but this hasn't been possible.

How Long Until We See New Names?

Once the researchers propose new names, the Inorganic Chemistry Division of the IUPAC will check them to make sure they don't translate into something funky in other language or have some prior historic use that would make them unsuitable for an element name. A new element may be named for a place, country, scientist, property, or mythological reference. The symbol needs to be one or two letters.

After the Inorganic Chemistry Division checks the elements and symbols, they are presented for public review for five months. Most people start using the new element names and symbols at this point, but they don't become official until the IUPAC Council formally approves them. At this point, the IUPAC will change their periodic table (and others will follow suit).