Chemistry textbooks are in need of a rewrite with the addition of four new elements to the Periodic Table. The International Union of Pure and Applied Chemistry (IUPAC) has confirmed the existence of four new elements with the atomic numbers 113, 115, 117, and 118, which were discovered by laboratories in Japan, the United States, and Russia. This bumper group of new elements completes the 7th row of the Periodic Table and clears the way for the discoverers to start thinking up names for them.

Until now, elements 113, 115, 117, and 118 have only been known from their gaps in the table and the temporary names ununtrium (Uut), ununpentium (Uup), ununseptium (Uus), and ununoctium (Uuo). Now, thanks to RIKEN in Japan; the Joint Institute for Nuclear Research in Dubna, Russia; Lawrence Livermore National Laboratory (LLNL), California; and Oak Ridge National Laboratory, (ORNL), Tennessee, these elements that do not exist in nature have been confirmed to have been created for the first time.

The fourth IUPAC and the International Union of Pure and Applied Physics (IUPAP) Joint Working Party (JWP) reviewed the findings of the discoverers and, based on a criteria set out in 1991, have confirmed them. Elements 115 and 117 were found by the Joint Institute for Nuclear Research, LLNL, and ORNL. Element 118 was found by the Joint Institute and LLNL, and 113 was found by RIKEN.

Illustration of element 117 discovered by LLNL Kwei-Yu Chu/LLNL

The periodic table in its modern form was invented by Russian chemistry professor Dmitri Mendeleev in 1869 and lists elements according to their atomic numbers based on the number of protons in their nuclei. Its odd shape, which is familiar to anyone trying to stay awake in chemistry class, is due to the discovery that by arranging the elements to group them by their chemical properties and electron configurations, it becomes a graphic representation of objective reality.

In other words, chemists could not only use the table to describe known elements, but also predict the existence and properties of unknown elements that were yet to be discovered. This makes the IUPAC announcement particularly important because it means that an entire row or period of the table has now been filled in thanks, in part, to this predictability.

Though many of the new elements were discovered as far back as 2004, the tricky bit has been proving that they exist. In the 19th century, any competent chemist could determine if a substance was a pure element, but the new elements reside in a part of the table where the atoms are super heavy and so unstable that they exist for less than a thousandth of a second.

Element 113, for example, was created by using a linear accelerator to bombard a thin layer of bismuth with zinc ions travelling at about ten percent of the speed of light in hope that, in rare instances, the bismuth and zinc atoms would fuse to form a element. The resulting super-heavy atom of 113 would then decay and turn into other unstable radioactive isotopes, which would decay nearly as fast.

The result was that the scientists who created the new element had to spend years tracing back the event through a labyrinth of isotopic breakdowns to prove that they descended from the new element. Then, the JWP of the IUPAC had to review the literature to make sure no mistakes were made.

Now that the elements are confirmed, the discoverers can officially apply permanent names and symbols to them. The proposed names and two-letter symbols will be checked by the Inorganic Chemistry Division of IUPAC and then be subjected to a public review for five months to make sure they conform to the standards of consistency, translatability into other languages, and historic use. Typically, names have been derived from mythology, minerals, geography, or the name of a scientist.

One other interesting point about the new elements is that it opens the way to the search for an "island of stability." That is, a region beyond the current Periodic Table where new superheavy elements will become stable and exist long enough to allow for conventional chemistry experiments.

The JWG findings will be published in the Pure and Applied Chemistry.

Source: IUPAC