Four new super-heavy chemical elements, currently using temporary names, complete the seventh row of the periodic table, International Union of Pure and Applied Chemistry (IUPAC) said on its website. Designated with atomic numbers 113, 115, 117 and 118, they were all discovered more than a decade ago.

Element 113 was discovered by the RIKEN collaboration team in Japan. Elements 115, 117 and 118 were created by a collaborative effort between the Joint Institute for Nuclear Research in Dubna, Russia, and Lawrence Livermore National Laboratory, California, while researchers from Oak Ridge National Laboratory in Tennessee were also involved in the discovery of elements 115 and 117.

“The chemistry community is eager to see its most cherished table finally being completed down to the seventh row. IUPAC has now initiated the process of formalizing names and symbols for these elements temporarily named as ununtrium, (Uut or element 113), ununpentium (Uup, element 115), ununseptium (Uus, element 117), and ununoctium  (Uuo, element 118),” Professor Jan Reedijk, president of the inorganic chemistry division of IUPAC, said.

The discoverers of the elements have the privilege to name their discoveries, and this will be the first time that an element will be named in Asia. According to IUPAC guidelines, new elements can be named after a mythological concept, a mineral, a place or country, a property or a scientist. It will be another few months before the new names and their two-letter symbols are introduced into the periodic table.

All the four elements were synthesized in laboratories and are rarely found in nature. They are called super-heavy elements because they are literally heavy, with very large nuclei. Element 118 is the heaviest element discovered so far.

“Probably the only other place where they might exist in a short period of time could be a supernova, where you have so much energy and so many particles that are really heavily concentrated,” Los Angeles Times quoted Dawn Shaughnessy, principal investigator for the Heavy Element Group at Lawrence Livermore National Laboratory.

Scientists are not resting easy with these discoveries, however. Kosuke Morita, who led the research at RIKEN, said his team now planned to “look to the unchartered territory of element 119 and beyond,” the Guardian reported.

The last time the periodic table was updated was in 2011, when elements 114 and 116 were added to it.