Remember how much fun you had memorizing the periodic table with its abbreviations, groups, and periods? Great! Because there are four more elements to add to the middle-school nightmares of your children and grandchildren. In December of 2015, four new elements were added by the International Union of Pure and Applied Chemistry (IUPAC) to the periodic table. Nihonium (Nh), Moscovium (Mc), Tennesine (Ts), and Oganesson (Og) made their entries to the table as elements 113, 115, 117, and 118, respectively. Here's the lowdown on these new additions.

Refresher

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The periodic table of elements organizes chemical elements by their atomic number, electron configuration, and chemical properties. The first step toward the construction of the table came in the form of a list of 33 elements published by Antoine Lavoisier in 1789. One century later, Dmitri Mendeleev put together the first periodic table of elements grouped with properties and leaving blank spaces for (what he rightly assumed were) undiscovered ones.

Progress

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By 1940, chemists had discovered all naturally occurring elements, including plutonium, neptunium, and astatine. These last three elements were initially synthesized in a lab before being observed in nature. These were likely the last elements that we would observe outside of a laboratory because increasing the number of protons in an atomic nucleus leads to instability. These larger elements quickly lose their protons through radiation to degrade to a smaller element.

However, an interesting property of the synthetic elements is observed when, by increasing proton number, the usually unstable intermediaries will show “islands of stability” where the nucleus remains intact for substantially longer than in intermediates. Element 117 was one of the first discovered islands of stability. Its decay chain isotope, lawrencium-266, showed a half-life of 11 hours, which is exponentially longer than elements of similar atomic weight.

Something old, something new

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“Newly” discovered is a relative term. Of the upcoming additions to the periodic table, several were synthesized in the early 2000s. However, before being incorporated into the table with IUPAC approval, the elements needed to be demonstrated to be reproducible. It has taken nearly a decade to demonstrate that these four elements are, in fact, reproducible islands of stability.

What’s in a name?

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The IUPAC standards set the ground rules for naming elements: they must refer to a scientist, mythology, substance, chemical property, or place. Of the newly incorporated elements, three follow the final rule. Tennessine, Moscovium, and Nihonium refer to the locale of the laboratory in which the elements were discovered: Tennessee, Moscow, and Japan. Oganesson takes the namesake of Russian nuclear physicist Yuri Oganessian at the Joint Institute for Nuclear Research, the same lab in which Moscovium was discovered. Oganesson is only the second element on the periodic table to be named after a person. Seaborgium is the other element, named after Glenn Seaborg.

Noble solid

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Of the new elements, Oganesson is perhaps the most interesting. It is the heaviest known element to date and falls into the group of noble gases, which are odorless, colorless, and inert. Oganesson’s chemistry is still left to be studied, but it appears to exhibit properties of the noble gases with the exception of the fact that it is a solid.

What’s next?

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Chemists will continue to synthesize elements exhibiting transitory states with short half-lives. It is expected that a new island of stability will be discovered with continued synthesis producing a superstable element that could last anywhere between minutes to millennia. The next superstable element is expected to occur at element 126, and though it’s impossible to envision the properties of a yet-to-be-discovered substance, the industrial applications of such an element could revolutionize science with possibilities for innovation in nuclear energy.