Today, Enewetak is a peaceful circular atoll in the Ralik Chain of the Marshall Islands in the South Pacific. But on the 1st of November, 1952, devastation replaced tranquility after the United States detonated an atomic bomb over the chain of small coral islands.
The test went as planned, with the bomb exploding with a force that was about 500 times more destructive than the Nagasaki blast that suddenly ended the war with the Japanese almost a decade prior. What was surprising was the discovery of a new element in the fallout material that was sent to Berkeley in California for analysis. This new element, known as Einsteinium after physicist Albert Einstein, occupies the 99th position in the periodic table and its properties have always been somewhat elusive -- until now.
A completely artificial atomic element
In a new study published in the journal Nature, researchers Berkeley National Laboratory in California used state of the art synthesis and analysis methods to reveal new insights about the physical and chemical properties of this rare heavy element.
Before this assessment, scientists knew that einsteinium has an atomic number of 99, placing it in the same actinide row as uranium. Other than that, there wasn't much known about Einsteinium due to it being difficult to create and its dangerously high radioactivity.
The researchers worked with less than 250 nanograms of the heavy element, which was manufactured at the Oak Ridge National Laboratory’s High Flux Isotope Reactor, one of the few places in the world capable of synthesizing einsteinium. Specifically, they analyzed einsteinium-254, one of the more stable isotopes of the element that has a half-life of 276 days, compared to a half-life of just 20 days for the more common isotope einsteinium-253. It's because of this short half-life that we never see einsteinium in nature, even if it was present during Earth's formation.
As you might imagine, working with einsteinium wasn't easy. The researchers had to overcome a number of setbacks, including contamination with californium, which is the 98th element, and delays due to the pandemic.
The solution was to bond the heavy radioactive metal with organic molecules called ligands, which acted as a luminescent antenna. After placing the einsteinium sample in a specialized container, the researchers beamed X-rays through it so they could measure the resulting spectrum.
This led to the discovery of the bond distance of einsteinium, a crucial property responsible for how metallic atoms bind to molecules. Along with other aspects of the elusive element's physical chemistry, these new insights may inform subsequent research and investigations. There is no current 'practical' use for einsteinium, but that may be set to change.
The very edge of the periodic table is still terra incognita so there are many things to learn, some fundamental to our understanding of physics and chemistry.