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Tennessine

physical science Maturity 9-11 Next article →

Tennessine is a synthetic element with the chemical symbol Ts. It holds the atomic number 117. This number represents the 117 protons found in its nucleus. It is an extremely heavy element. In fact, it shares the joint-highest atomic mass of all known elements. Tennessine is also the penultimate element of the 7th period on the periodic table.

DecayChain Tennessine
DecayChain Tennessine

Because it is man-made, it does not occur naturally in the environment. Scientists study it to understand how matter behaves at the extreme edge of the periodic table.

Creating tennessine requires a complex process called nuclear fusion. Scientists aim to fuse two lighter nuclei to create a much heavier one. To do this, they use a target made of berkelium, which has 97 protons. They then bombard this target with a beam of calcium-48 nuclei. Calcium-48 is a specific isotope with 20 protons and 28 neutrons. This high neutron-to-proton ratio of 1.4 is very important. The extra neutrons help the resulting nuclei become heavier. This makes the new atoms closer to a theoretical region called the "island of stability."

Berkelium
Berkelium

In this island, some superheavy elements might be more stable than others.

In the periodic table, tennessine is expected to be a member of group 17. This group is known as the halogens. These include familiar elements like fluorine and chlorine. However, tennessine may behave quite differently from its lighter relatives. This is due to relativistic effects, which are changes caused by the high speeds of electrons. Because of these effects, tennessine is expected to be a volatile metal. It may not form anions or achieve high oxidation states like other halogens. Still, some properties like melting and boiling points should follow general periodic trends.

The discovery of tennessine was a massive international effort. A Russian–American collaboration led the research. Key institutions included the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. They also worked with the Oak Ridge National Laboratory (ORNL) in Tennessee. Other partners included Vanderbilt University and Lawrence Livermore National Laboratory. Clarice Phelps was a member of the ORNL team. Her involvement is notable because she was the first African-American woman involved in discovering a new element.

CorneliusVanderbiltStatue
CorneliusVanderbiltStatue

The discovery was officially announced in Dubna in April 2010.

The path to discovery was long and expensive. In 2004, researchers proposed the experiment to synthesize element 117. However, they first had to acquire berkelium. At that time, ORNL had stopped producing it. Re-starting production would have cost about 3.5 million dollars. The team had to wait for a commercial order of californium to extract berkelium as a by-product. In 2008, ORNL resumed production. They produced 22 milligrams of berkelium, which was enough for the experiment. This material had a half-life of only 330 days. This means half of the substance would decay every 330 days.

Island of Stability derived from Zagrebaev
Island of Stability derived from Zagrebaev

Moving the material was a logistical challenge. The berkelium target had to be transported from the United States to Russia quickly. The experiment had to be completed within six months of its departure. The target was packed into five lead containers for the flight. Interestingly, the target traveled across the Atlantic Ocean five times. This happened because Russian customs officials twice refused entry due to paperwork issues. The material finally arrived in Russia in June 2009. It was then placed on a titanium film in Dimitrovgrad. By July 2009, it was installed in the particle accelerator at JINR.

Once the experiment began, the results were tiny and fleeting. The synthesized tennessine atoms lasted only tens or hundreds of milliseconds. Scientists detected the element by watching its decay chains. One isotope underwent six alpha decays before spontaneous fission. Another isotope underwent three alpha decays before fission.

Valence atomic energy levels for Cl, Br, I, At, and 117
Valence atomic energy levels for Cl, Br, I, At, and 117

In 2011, scientists created a daughter isotope directly. This helped confirm the original results. The discovery was officially recognized by the IUPAC and IUPAP in December 2015. The name tennessine was officially adopted in November 2016. This name honors the region of Tennessee where the research took place.

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🖼️ Images & Media (5)
File:Berkelium.jpg
Berkelium.jpg
File:DecayChain Tennessine.svg
DecayChain Tennessine.svg
File:CorneliusVanderbiltStatue.JPG
CorneliusVanderbiltStatue.JPG
File:Island of Stability derived from Zagrebaev.svg
Island of Stability derived from Zagrebaev.svg
File:Valence atomic energy levels for Cl, Br, I, At, and 117.svg
Valence atomic energy levels for Cl, Br,...
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