Francium

Francium (chemical symbol: Fr) is a chemical element with atomic number 87. It belongs to the alkali metal group, which also includes lithium, sodium, potassium, rubidium, and cesium. All of its isotopes are radioactive, and none have stable forms.

Francium is one of the rarest naturally occurring elements on Earth. It is produced when heavy elements such as actinium undergo radioactive decay. Because of its short lifespan, only tiny quantities are ever found, and these quickly transform into other elements.

Discovery

The element was identified in 1939 by Marguerite Perey, who worked at the Curie Institute in Paris. She observed that the isotope actinium-227 partially decays to produce a new element with atomic number 87. The name 'francium' derives from the country of France.

Chemical properties

Francium has one electron in its outermost shell, making it highly reactive. Like other alkali metals, it readily loses this electron to form a positive ion (Fr+). Theoretically, it is the least electronegative element in its group, but most measurements are computational predictions rather than direct measurements, since sufficient quantities cannot be accumulated for testing.

Isotopes and stability

The most stable isotope is francium-223, with a half-life of approximately 22 minutes. Other isotopes are shorter-lived. For this reason, francium cannot be stored, cannot be used in industry, and emits radioactivity as it decays.

Applications

Francium has no commercial applications. It is used only in scientific research, particularly in atomic physics experiments: because of its large atomic structure, it is employed to study weak interactions and to test theoretical predictions. It is produced in small quantities in particle accelerators.