87 Fr 223
Francium
ALKALI METAL
Phase: Solid
Discovered: Marguerite Perey
Block: S
Summary
Francium is a chemical element with symbol Fr and atomic number 87. It used to be known as eka-caesium and actinium K. It is the second-least electronegative element, behind only caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon.
Source: WikipediaPhysical Properties
Atomic Mass 223 u
Density 1.87 g/cm³
Melting Point 300 K
Boiling Point 950 K