- Francium is a chemical element; it has symbol Fr and atomic number 87. It is extremely radioactive; its most stable isotope, francium-223 (originally called actinium K after the natural decay chain in which it appears), has a half-life of only 22 minutes. It is the second-most electropositive element, behind only caesium, and is the second rarest naturally occurring element (after astatine). Francium’s isotopes decay quickly into astatine, radium, and radon. The electronic structure of a francium atom is [Rn] 7s1; thus, the element is classed as an alkali metal.
- Southeast Europe (Wikipedia)
Southeast Europe or Southeastern Europe (SEE) is a geographical sub-region of Europe, consisting primarily of the cultural region of the Balkans, as well as adjacent regions and archipelagos. There are overlapping and conflicting definitions of the region, due to political, economic, historical, cultural, and geographical considerations.