We now know more about the mysterious element einsteinium

Since its discovery in 1952, almost nothing was known about einsteinium. But today, finally, a team of chemists has managed to discover some of its completely unexpected chemical properties

(photo: Wikimedia commons) It is the 99th element of the periodic table and was discovered in the laboratory of the Lawrence Berkeley National Laboratory in the distant 1952, during the test of the first hydrogen bomb. It is einsteinium, very rare, radioactive and extremely difficult to produce, so much so that so far very few experiments have been carried out on it. But today, some fundamental chemical properties of this mysterious element have been discovered for the first time. This was achieved by a team of chemists, coordinated by the Berkeley Lab, who were able to better characterize einsteinium, and thus pave the way for a greater understanding of all 14 metallic elements of the actinoid (or actinide) series, which they range from actinium to laurentius. The study was published in the journal Nature.

Using only 250 nanograms of einsteinium and innovative experimental techniques not available decades ago, when the element was first observed, the researchers were able to study its chemical behavior and to determine the bond distance (the average length between two bonded atoms), a basic property fundamental to predicting how it interacts with other elements. "Not much is known about einsteinium," said Rebecca Abergel, one of the authors of the study. “It is an extraordinary result that we have been able to achieve with this small amount of material. It is important because the more we understand its chemical behavior, the more we can use this knowledge to develop new materials or new technologies, not necessarily only with einsteinium, but also with the rest of the actinides ".

But arriving at a similar result was not at all easy. To begin with, the material was made at the High Flux Isotope Reactor of the Oak Ridge National Laboratory, one of the very few places in the world capable of producing einsteinium, which consists of bombarding a target element, curium, with neutrons. to trigger a long chain of reactions. Producing the pure element, however, is a really challenging undertaking. In fact, the sample used in the study was contaminated with a large amount of californium, and the researchers ended up with only one tiny sample of einsteinium-254, one of the most stable isotopes of the element, which has a half-life (the time in which half of element decays) by 276 days.

Another obstacle was the coronavirus pandemic. Due to the closures and delays, in fact, when the researchers were able to return to the laboratory in late summer, most of the sample had disappeared, not allowing the team to carry out all the planned experiments. With that even smaller amount of einsteinium, however, they were able to measure the bond distance, discovering a completely unexpected and counter-trend chemical-physical behavior with respect to elements from the actinoid series. “Determining the bond distance might not sound interesting, but it's the first thing you need to know about how a metal binds to other molecules,” explains Abergel. "By obtaining this data, we have a better and broader understanding of how the entire series of actinides behave. And in that series, we have elements or isotopes useful for the production of nuclear energy or for radiopharmaceuticals ”. Data that, the researchers speculate, could also offer the possibility of discovering a new element. “We are really starting to understand a little better what happens towards the end of the periodic table, and we can begin to imagine discovering new elements,” concludes Abergel.