Making mendelevium, one atom at a time

Component quantity 101, mendelevium, is called after Dmitry Mendeleev, the person behind the periodic desk.
| Photograph Credit score: Wikimedia Commons

The seek for new parts is one thing that scientists have been doing for lots of of years. As soon as Russian chemist Dmitri Mendeleev organised the weather recognized at his time in accordance with a repeating, or periodic (and therefore the identify periodic desk), system within the 1860s, the search grew to become a bit simpler.

This was as a result of the gaps in Mendeleev’s periodic desk pointed to parts that weren’t recognized but. The properties of those parts, nevertheless, could possibly be predicted primarily based on their place within the desk and the neighbours round them, thereby making it simpler to find new parts. Mendeleev’s desk has since been expanded, to create space for different new parts.

A kind of new parts found was aspect quantity 101, named mendelevium after Mendeleev. American Nobel Prize winner Glenn Seaborg, who was one of many discoverers of the aspect, wrote that the invention of mendelevium was “one of the most dramatic in the sequence of syntheses of transuranium elements”, in a chapter co-written by him for The New Chemistry. Moreover, he additionally wrote in that chapter that “It was the first case in which a new element was produced and identified one atom at a time.”

Begins with a bang

Ivy Mike, the primary thermonuclear gadget, was dropped for testing on the Eniwetok Atoll within the Pacific Ocean in 1952, sending a radioactive cloud into the air, from which samples had been collected. The lab experiences advised that two new parts – parts 99 (einsteinium) and 100 (fermium) – had been found from the particles. The discoveries got here at a time when there was a race to find new parts.

The main researchers of the U.S. concerned on this race had been camped on the Radiation Laboratory on the College of California, Berkeley, below the path of physicist Ernest Lawrence. A workforce of scientists which included Albert Ghiorso, Stanley Thompson, Bernard Harvey, Gregory Choppin, and Seaborg, got here up with a plan to supply aspect 101 utilizing a billion atoms of einsteinium-253 that had been shaped in a reactor.

The concept was to unfold the atoms of einsteinium onto a skinny gold foil. As its half-life was about three weeks, the researchers successfully had every week to carry out their experiments after receiving it. Based mostly on Ghiorso’s calculations, they had been conscious that solely about one atom of the brand new aspect 101 could be produced for each three hours the gold foil was bombarded with alpha particles.

Race in opposition to time

Because the experiment would yield solely a really small quantity of the brand new aspect, the scientists arrange a second gold foil behind the primary to catch the atoms. It was a race in opposition to time in addition to the half-life of aspect 101 was anticipated to be a couple of hours solely.

With the Radiation Laboratory atop a hill and the cyclotron at its base, there actually was a mad rush to get the samples to the lab on time. The samples “were collected in a test tube, which I took and then jumped in a car driven by Ghiorso”, is how Choppin put it in his personal phrases.

On the evening of the invention, the goal was irradiated in three-hour intervals for a complete of 9 hours. By 4 AM on February 19, 1955, that they had recorded 5 decay occasions attribute of aspect 101 and eight from aspect 100, fermium. With conclusive proof of aspect 101’s existence, Choppin mentions that “We left Seaborg a note on the successful identification of Z =101 and went home to sleep on our success.”

On the finish of April 1955, the invention of aspect 101 was introduced to the world. The college’s press launch acknowledged that “The atoms of the new element may have been the rarest units of matter that have existed on earth for nearly 5 billion years…The 17 atoms of the new element all decayed, of course, and the ‘new’ element is for the present extinct once again.”

Chilly Battle period

As aspect 101 marked the start of the second hundred parts of the periodic desk, the scientists wished to call it after Mendeleev, the person behind the periodic desk. Regardless of the invention occurring in the course of the Chilly Battle period, Seaborg was in a position to pull sufficient strings to persuade the U.S. authorities to just accept the proposal to call the aspect after a Russian scientist. The Worldwide Union of Pure & Utilized Chemistry accepted the identify mendelevium and the scientists revealed their discovery within the June 1955 challenge of Bodily Overview Letters.

Whereas solely small portions of mendelevium have ever been produced, extra secure isotopes of the aspect have since been made. Probably the most secure model often known as of now has a half-life of over one-and-a-half months, permitting for higher alternatives to additional examine heavy parts and their properties.