Name: formerly known as eka-caesium or actinium K.
Symbol Fr; atomic number 87.
PhysicsFrancium is an extremely rare element due to its radioactive decay.
Francium decays into astatine, radium, and radon. The half-life of its longest-lived isotope is only 22 minutes. It is assumed that francium would appear as a highly reflective metal. It will immediately vaporize in any viewable quantity of the element, due to the impossible, since the extreme heat of decay.
It is the least electronegative element.
Francium is an alkali meta with one valence electron.
It was the last element discovered in nature, in 1939.