Francium

Francium was discovered in 1939 by the French physicist Marguerite Perey at the Curie Institute in Paris. It was named after France, the country of its discovery. During her research on actinium, Perey identified a new isotope of element 87 in the decay chain of actinium-227. Francium was the last naturally occurring element to be discovered, mainly due to its extreme rarity and radioactivity. Initial estimates of its abundance were highly inaccurate, and it wasn't until Perey's discovery that researchers understood just how scarce francium actually is, with estimated amounts of no more than 30 grams present in the Earth's crust at any one time. Due to its short half-life, the isotopes of francium are amongst the least-studied elements. This has contributed to a limited understanding of its properties compared to more stable alkali metals.

Francium is found in trace amounts in uranium and thorium ores, where it is a decay product of actinium. The most stable isotope, francium-223, has a half-life of about 22 minutes, which is extremely short and renders the element elusive for researchers. Because of this brief existence, francium is not accumulated in any significant concentration in nature, and it represents one of the least common elements in the Earth’s crust. Most francium today is artificially produced in laboratories, where nuclear reactions are employed to create it from other elements or isotopes. Its rarity and the challenges associated with its study make it a particularly intriguing subject for chemists and nuclear scientists alike.

Francium has no known biological role and appears to be toxic due to its radioactivity. Due to its extreme rarity and short half-life, francium does not naturally accumulate in living organisms, nor does it participate in biological processes. Thus, there is no significance associated with its presence in biological systems, unlike other alkali metals such as sodium and potassium, which play crucial roles in cellular processes and maintaining physiological balance. Its radioactive nature suggests that exposure to francium could have harmful effects; however, due to its scarcity, practical concerns regarding francium's impact on living organisms are largely academic.

Francium is classified as an alkali metal and shares many properties with its group members lithium, sodium, potassium, rubidium, and cesium. It is expected to be soft and malleable, with a low melting and boiling point, though exact values are difficult to ascertain due to its radioactivity and instability. Preliminary data suggest that francium may have a melting point around 27°C and a boiling point near 677°C. Chemically, francium is highly reactive, especially with water and air, and it is likely to form francium hydroxide and francium oxide in reactions with water and oxygen, respectively. Its reactivity decreases down the group, but due to the limited study of francium, detailed chemical behavior is yet to be fully elucidated. Its atomic radius is predicted to be larger than that of cesium, thereby influencing its chemical interactions.

Due to its extreme rarity, radioactivity, and short half-life, francium has limited practical applications outside of scientific research. Its primary use is in studies concerning atomic structure and the behavior of radioactive elements. Researchers may utilize francium isotopes in nuclear research and in studies aimed at understanding the isotopes' decay processes and properties. However, no significant industrial applications currently exist for francium, given that other elements serve similar functions without the associated hazards of radioactivity.

• Francium is one of the most expensive elements on Earth, estimated to cost around $1 billion per gram.
• The most stable isotope, francium-223, decays into lead-207 through a series of radioactive decay steps.
• Marguerite Perey, the discoverer of francium, was only the second woman to be awarded a doctorate in the field of nuclear physics in France.
• Francium is so rare that it is estimated that there is only about 30 grams of francium in the entire Earth's crust at any given time.