When the holidays are over, lots of us feel a bit bigger than we were before we started stuffing our faces with cocktails and Christmas cookies. This year, people aren't the only things starting 2016 a little larger. The periodic table of the elements is also seeing a size increase.
On December 30, the International Union of Pure and Applied Chemistry (IUPAC) approved four new elements for inclusion in the table. They bear the atomic numbers 113, 115, 117 and 118.
"The chemistry community is eager to see its most cherished table finally being completed down to the seventh row," Professor Jan Reedijk, president of the inorganic chemistry division of IUPAC, said in a statement.
As you might remember from high school chemistry class, an element's atomic number indicates the count of protons in its nucleus. The larger the number of protons, the higher the atomic number, and the "heavier" the element is considered to be.
Plutonium (atomic number 94) and uranium (atomic number 92) are widely considered to be the heaviest elements in nature. Elements beyond that have to be created in a lab when scientists slam elemental nuclei together. Because the smooshed-together protons in the nuclei of these lab-made elements repel each other, they are extremely unstable and only last for fractions of a second before decaying into more stable elements.
Although just approved by the IUPAC for inclusion on the periodic table, each of the newly added elements were discovered previously -- sometimes years ago.
Russian scientists, for example, claimed to have spotted element 115 -- temporarily known as ununpentium -- in 2003. It took more labs to confirm the existence of the element for IUPAC to sign off on it -- not an easy task, as its half-life is only 173 milliseconds. Element 117, with a half-life of about 50 thousandths of a second, was first discovered by a joint Russian-American team in 2010.
Now the IUPAC is finally satisfied about the existence of the elements. It's giving credit for ununpentium (which means 1-1-5 in Latin), along with ununseptium (117) and ununoctium (118) to a joint Russian/American team. Credit for element 113, ununtrium, goes to a team in Japan. The elements are now to be named by the teams that confirmed their existence. "New elements can be named after a mythological concept, a mineral, a place or country, a property or a scientist," the IUPAC says.
Prior to the new batch, the last elements to be added to the periodic table were flerovium (114), named in honor of Russia's Flerov Laboratory of Nuclear Reactions where it was discovered, and livermorium (116), named after the Lawrence Livermore National Laboratory, which collaborated with a Russian group on its discovery.
Because all of these elements at the high end of the periodic table decay so quickly, they don't have any practical applications. Scientists do hope to one day discover "an island of stability" at the heavier end of the chart that would contain elements that would stick around longer than just fractions of a second.
The periodic table of the elements was first published in 1869 by Russian chemist Dmitri Mendeleev. At that time, it contained 63 entries. With the new elements added on December 30, the table now contains almost double that amount at 118.