Seeing my addition to this post going around again and this comment has prompted me to clarify something:
Marguerite Perey is one of the greatest radiochemists to ever live, and Francium is such a bullshit element that only an absolute master could identify and analyze it.
The short-lived intermediate actinide chain isotopes are mostly bullshit elements for a lot of the same reasons Francium is. Five of them (Radium, Radon, Astatine, Actinium, and Protactinium) are so scarce in nature and so ferociously radioactive that all of their names literally mean “unstable or radioactive element” because at the time of their discovery that was the only thing known about them. Isolating and identifying these bullshit elements demanded a total technical mastery of the cutting edge chemical and radiological analysis techniques in their time, as well as performing a tremendous amount of brutal physical labor. Preparing these extreme trace elements for study required processing thousands of pounds of raw uranium and thorium ores, often exposing the researchers and their assistants to high doses of radiation, just to obtain the extremely radioactive milligram-scale quantities of the intermediate isotopes they wished to study.
To even have the skills to identify Francium, Perey had to first spend years mastering the separation of transactinide decay products from raw mixed ore at the Radium Institute with her mentor and another true master in the field, Marie Skłodowska-Curie. Her work in Curie’s lab focused on the isolation and analysis of another previously discovered bullshit decay product, the obviously-named Actinium. Actinium occurs in high-grade natural uranium ores at a rate of 0.2 mg Ac/1000 kg ore, a concentration of 0.0000002%wt, so isolating enough of it to study required the painstaking and precise process of dissolving and refining thousands of tons of increasingly radioactive metals in powerful and dangerous solvents.
Upon isolation of a sample of Actinium (specifically Actinium mixed into a Lanthanum carrier) , Perey and the Curies would frantically study the element as its already intense radioactivity multiplied while even shorter-lived isotopes of Thorium, Radium, Radon, Polonium, and others grew in to the sample, obscuring its characteristics and endangering the researchers.
The decay of Actinium should have only initially produced beta radiation from its decay into Thorium-227, which in turn undergoes alpha decay into Radium-223. The days-long lifetime of Thorium-227 means that after a fairly short period of time, the Actinium sample will develop a significant amount of alpha radiation on its own. But Perey was skilled enough and fast enough to isolate and measure her samples before this process could happen, and what she found was an unexplained early spike in alpha radiation from some other very scarce very active alpha source, something that must have been decaying directly from the Actinium in minuscule quantities.
After analyzing several samples to make sure these results were reliable, Perey was confident she had discovered the elusive element 87, and asked Jean Perrin (her supervisor at the lab) to submit her findings for publication. At the time, she was a lab assistant and unable to publish papers, and did not get a degree until 1946, seven years later. She named the new element Francium, after her home country and the nation that sponsored her research.
While Perey was investigating the properties of Actinium, her mentor Marie Curie developed serious anemia and had to withdraw from lab work. She died of aplastic anemia in 1934, after years of continuous exposure to extreme radiation that destroyed her bone marrow and left her body unable to produce new blood cells. Perey discovered Francium five years later.
The dangers of working with highly radioactive elements were not well understood in the early era of radiochemistry, but the experiences of the early radiochemists left a huge impact on those that followed, and Perey championed studies of the effects of radiation and devised new protection methods for researchers throughout her long career. Though she was nominated five times for the Nobel Prize, she never won it, and her contributions and talent have been largely forgotten outside of the nuclear chemistry community.
The level of skill and care required to discover an element that is so immensely bullshit as Francium is staggering, and the numbers involved are unimaginable. The labs Perey and the Curies worked in were left unused for decades until their destruction in 1981, due to the intense radioactivity from sub-microgram quantities of these highly active elements contaminating the room. It’s likely that Perey never observed more than a nanogram of Francium during her lifetime studying it, and no quantity large enough to observe its bulk quantities has ever been assembled.
I will talk shit about the element because it’s a nightmare atom, but I will not tolerate any kind of slander of Marguerite Perey, one of the best to ever do it.
