What can fascinate you more than the periodic table? The periodic table lists over a hundred elements where most are naturally occurring while others artificially discovered. Like many artificially discovered elements, Einsteinium (numbered Z=99) was discovered in 1952 at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) from the debris of the first hydrogen bomb. Due to its highly radioactive nature, very few experiments had been done on it. However, a team of Berkeley Lab chemists has overcome these obstacles to report the first study characterizing some of its properties.
This study was published in the journal Nature, heading “Structural and Spectroscopic Characterization of an Einsteinium Complex” which was co-led by Berkeley Lab scientist Rebecca Abergel and Los Alamos National Laboratory scientist Stosh Kozimor, and included scientists from the two laboratories, UC Berkeley, and Georgetown University, several of whom are graduate students and postdoctoral fellows. Faced with several challenges the team was able to measure the bond-length of Einsteinium.
“This whole paper is a long series of unfortunate events”, said Abergel, who leads Berkeley Lab’s Heavy Element Chemistry group.
Getting the sample in a usable form was almost half the battle. The group faced their first problem when they tried synthesizing the sample at Oak Ridge National Laboratory’s High Flux Isotope Reactor. However, since the sample was contaminated by a significant amount of californium they had to abandon their original plan to use X-ray crystallography and instead came up with a new way to make samples and leverage element-specific research techniques.
Then, contending with the radioactivity was another challenge. The lab experimented with Einsteinium- 254 having a half-life of 276 days which is one of the most stable isotopes of the element. But the pandemic-related shutdowns foiled their follow-up experiments, although the team was able to conduct many of the experiments before that. The group later have to conduct their study with a lot of sample missing.
Despite all these the researchers were able to measure a bond distance with einsteinium and also discovered some physical chemistry behaviour that was different from what would be expected from the actinide series. This discovery will help in understanding how the metal binds with other molecules and the kind of chemical reaction exhibited by the element with other atoms or molecules, thus helping in a better understanding of the whole actinide series.
“We’re really starting to understand a little better what happens toward the end of the periodic table, and the next thing is, you could also envision an einsteinium target for discovering new elements,” Abergel said. “Similar to the latest elements that were discovered in the past 10 years, like tennessine, which used a berkelium target, if you were to be able to isolate enough pure einsteinium to make a target, you could start looking for other elements and get closer to the (theorized) island of stability”.
Reference: https://www.nature.com/articles/s41586-020-03179-3
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