Francium

Francium holds two extreme records: it is the most unstable naturally occurring element and the second rarest (after astatine). Discovered in 1939 by Marguerite Perey at the Curie Institute in Paris, francium was named after France. Perey was the first woman elected to the French Academy of Sciences, partly due to this discovery.

Francium is so radioactive that its most stable isotope, francium-223, has a half-life of only 22 minutes. Scientists estimate that at any moment, there are only about 30 grams of francium in the entire Earth's crust. No one has ever collected enough francium to see what it looks like in bulk, but based on its chemistry, it would be a highly reactive alkali metal that would explode on contact with water even more violently than cesium.

Francium's symbol 'Fr' is a useful two-letter element in Spellement. It matches the start of words like 'free,' 'friend,' and 'from,' fitting a very common English consonant pair. This makes francium a natural and practical choice for building creative element-based word spellings.