5th

Francium is a chemical element with symbol Fr and atomic number 87. It was formerly known as eka-caesium and actinium K. It is one of the two least electronegative elements, the other being caesium.

Symbol: Fr
Electron configuration: Rn 7s1
Melting point: 80.6°F (27°C)
Atomic number: 87
Boiling point: 1,250°F (676.8°C)
Electronegativity: 0.7
Atomic mass: 223 u