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The Sciences

It's Time to Update the Periodic Table, Again

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Image Credit: Maximilian Laschon The periodic table just got a little bigger. The International Union of Pure and Applied Chemistry (IUPAC) has officially confirmed the existence of four new elements with atomic numbers 113, 115, 117 and 118, completing the seventh row, or period, of the periodic table.

Filling Up the Periodic Table

The elements’ existence has been documented by researchers from Russia and the United States, as well as a separate team from Japan, for several years, but they awaited official review by the IUPAC to be formally accepted. Now that the confirmation process is complete, the researchers will submit permanent names for their elements. The IUPAC states that elements can be named after a mythological concept, a mineral, a place or country, a property or a scientist. The elements are currently known by placeholder names, such as the ever catchy ununseptium for element 117. The four newest discoveries will join other “superheavy” elements in the seventh period of the periodic table, including flerovium and livermorium, which were added in 2011. A team of researchers from Japan's Riken Institute led by Kosuke Morita first discovered evidence of element 113, or ununtrium, back in 2004 when they shot a beam of zinc ions at a thin layer of bismuth, and confirmed their finding in 2012. Moving at 10 percent the speed of light, the nuclei of both atoms occasionally fused together, creating an element with 113 protons.

Gone in the Blink of an Eye

Don’t go looking for these new additions to the periodic table, however. Due to their volatile nature, all of the newfound elements exist only in the lab, and disappear soon after they form. As with all elements beyond uranium, these new elements are radioactive, meaning they decay into other elements over time by releasing pairs of protons and neutrons called alpha particles. Superheavy elements have particularly brief lifespans, often disappearing a fraction of a second after they are created. Newly minted 113, for example, exists for less than a thousandth of a second before it decays into roentgenium.

Proof Difficult to Obtain

The brief existence of superheavy elements makes it hard to prove they are real. It took Morita’s team almost a decade to definitively show their element existed after they initially discovered it. They accomplished this by looking at the chain of decay the element goes through on its way to becoming stable. Most radioactive elements don't transition directly to stable atoms, but instead go through a cascading series of unstable ones, jettisoning protons and neutrons bit by bit as they become more stable. With time and luck, the researchers observed their element at every stage of its decay into known elements, beginning with roentgenium and ending with mendelevium. Extremely short lifespans make these new elements effectively useless for practical applications. However, these new discoveries take researchers one step closer to the so-called “Island of Stability,” a region of the periodic table where elements that are both superheavy and stable are thought to exist, and which is believed to begin around atomic number 120. While none of these atoms have been discovered yet, their existence is predicted by the “magic number” theory. The theory says that certain numbers of protons and neutrons are more stable than others, as they create completely filled energy shells within the nucleus. While creating these mythical elements is exciting, the biggest priority at the moment is finding a name for the newest additions to the periodic table. Any suggestions?

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