Does the periodic table ever end? That becomes a real question after the discovery (manufacture, really) of a new element, temporarily called ununseptium (Latin for 117) with an atomic weight of 117. This element was especially difficult. Elements 116 and 118 were already produced. Physicists knew the gap element existed but to produce it required a relatively large amount of another very rare element berkelium 97.
It required Berkelium 97 because the collision material for the accelerator would be Calcium 20. Do the math: 97 + 20. Colliding these two elements could produce the elusive 117, and it did.
One of the highlights of this discovery is its international pedigree:
- The High Flux Isotope Reactor in Oak Ridge National Laboratory (Tennessee, USA) created 22 mg of berkelium after 250 days of intense neutron flux radiation.
- The Oak Ridge team then spent 90 days purifying the berkelium.
- The Research Institute for Advanced Reactors (Dimitrovgrad, Russia) prepared the calcium and berkelium for the accelerator.
- The Joint Institute of Nuclear Research (Dubna, Russia) used its U400 cyclotron accelerator for 155 hours of calcium-berkelium collisions.
- Initial data analysis was performed at Dubna.
- The data was shipped to Lawrence Livermore Labs (California, USA) for further analysis.
- Scientists from Vanderbilt University (Tennessee, USA) and the University of Nevada (Las Vegas, USA) also participated.
The process of creating element 117 needed to fall within the 320 day half-life of berkelium, so in terms of costs, this was close to being a one-time shot.
It’s already a big deal to add an element, but this one has something extra (besides a proton). It completes the 7th row of the periodic table and it suggests that there are more elements to be found. The theoretical models say there could be many more elements. Physicists think some of those elements may be much more stable – they might even hang around long enough to perform experiments with them. Many of the elements since Uranium 92, the last naturally occurring element, are so ephemeral (lasting femtoseconds in some cases) about all that can be done is to certify they exist. However beyond 118, the addition of protons may lead to what is called an ‘island of stability’ around 120 to 124 where the extra weight helps keep the element from breaking apart.
If this is true – and at this point nobody knows for sure – then not only does the periodic table continue; there may be some very unusual elements in the offing with properties that at this point are hard to imagine. ¬¬¬
“These new elements expand our understanding of the universe and provide important tests of nuclear theories,” said Vanderbilt University Professor of physics Joe Hamilton. “The existence of the island of stability, a pure theoretical notion in the 1960s, offers the possibility of further expansion of the periodic table with accompanying scientific breakthroughs in the physics and chemistry of the heaviest elements.”
[Source: Oak Ridge National Laboratory]
This is heading into new territory, the unknown. It may have nothing except the end of the periodic table. It may have new worlds. Ladies and gentlemen, start your cyclotrons.